JP7735995B2 - Zoom lens and imaging device - Google Patents

Description

The present disclosure relates to a zoom lens suitable for, for example, a mirrorless camera system, and an imaging device equipped with such a zoom lens.

Interchangeable-lens digital camera systems have rapidly become popular in recent years. Patent documents 1 and 2, for example, propose ultra-wide-angle zoom lenses that have an angle of view exceeding 100 degrees at the wide-angle end as zoom lenses that can be used in such camera systems. The zoom lenses proposed in Patent documents 1 and 2 are retrofocus types that ensure a long flange focal distance. Meanwhile, mirrorless digital cameras, which are interchangeable-lens digital camera systems that do not have a quick-return mirror inside the camera body, are attracting attention. Mirrorless camera systems have a shorter back focus (distance from the lens closest to the image plane to the image sensor) than reflex camera systems.

JP 2015-138122 A Japanese Patent Application Laid-Open No. 2018-189733 JP 2018-87903 A

For example, Patent Document 3 proposes an ultra-wide-angle zoom lens with a short flange focal distance that is suitable for mirrorless camera systems, but there is a demand for the development of a brighter, higher-performance zoom lens with a shorter overall optical length.

It is desirable to provide a bright, high-performance zoom lens with a short optical length, and an imaging device equipped with such a zoom lens.

A zoom lens according to an embodiment of the present disclosure is composed of, in order from the object side to the image surface side, a first group having negative refractive power, a second group having positive refractive power, an intermediate group having one or more lens groups, and a final group having three or more lens components and negative refractive power, wherein the spacing between adjacent groups changes when zooming from the wide-angle end to the telephoto end, and the three or more lens components in the final group include a first lens component having negative refractive power and located third closest to the image surface, a second lens component having negative refractive power and located second closest to the image surface, and a third lens component having positive refractive power and located closest to the image surface.
The second lens component may be a single lens with a concave surface facing the object side.
Furthermore, the surface of the second lens component closest to the object side may be formed with an aspherical surface such that the amount of sag with respect to the paraxial spherical surface is greater in the periphery than in the center.
Furthermore, when the Abbe number of the third lens component is vd and the partial dispersion ratio is ΘgF, the following conditional expression may be satisfied.
νd>70...(1)
0.015<ΔΘgF<0.1...(2)
however,
ΔΘgF=ΘgF-0.6483+0.001802×νd
Θgf=(ng-nF)/(nF-nC)
νd=(nd-1)/(nF-nC)
nd: refractive index of the third lens component with respect to the d line
ng: refractive index of the third lens component for the g-line
nF: refractive index of the third lens component for the F line
nC: refractive index of the third lens component with respect to the C line
Let's say.
Furthermore, the second group may move along the optical axis when focusing from an object distance of infinity to a close distance, and the surface closest to the object may be convex toward the object side, and the lens group in the intermediate group that is positioned closest to the image plane may have positive refractive power, and may move toward the image plane when focusing from an object distance of infinity to a close distance at the telephoto end, and may satisfy the following conditional expression:
1.5<R2GF/fw<5...(4)
however,
R2GF: Radius of curvature of the surface in the second group closest to the object
fw: focal length of the entire system at the wide-angle end
Let's say.
The second lens unit may have, at the most object side, a lens that satisfies the following condition:
Nd2G>1.8...(5)
however,
Nd2G: refractive index for the d-line of the lens closest to the object in the second group
Let's say.

An imaging device according to one embodiment of the present disclosure includes a zoom lens and an imaging element that outputs an imaging signal corresponding to an optical image formed by the zoom lens, and the zoom lens is configured by the zoom lens according to the embodiment of the present disclosure.

A zoom lens or imaging device according to one embodiment of the present disclosure is composed of five or more groups overall, with the configuration of each group optimized to enable a short overall optical length and bright, high-performance performance.

1 is a lens cross-sectional view showing a first configuration example (Example 1) of a zoom lens according to an embodiment of the present disclosure. 5A to 5C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 1 at the wide-angle end and when focused on infinity. 5A to 5C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 1 at the telephoto end when focused on infinity. 5A to 5C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 1 at the wide-angle end when focusing on a close distance. 5A to 5C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 1 at the telephoto end when focusing on a close object. FIG. 1 is a lens cross-sectional view showing a second configuration example (Example 2) of a zoom lens according to an embodiment. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 2 at the wide-angle end and when focused on infinity. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 2 at the telephoto end when focused on infinity. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 2 at the wide-angle end when focusing on a close distance. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 2 at the telephoto end when focusing on a close object. FIG. 10 is a lens cross-sectional view showing a third configuration example (Example 3) of a zoom lens according to an embodiment. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 3 at the wide-angle end and when focused on infinity. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 3 at the telephoto end when focused on infinity. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 3 at the wide-angle end when focusing on a close distance. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 3 at the telephoto end when focusing on a close object. FIG. 10 is a lens cross-sectional view showing a fourth configuration example (Example 4) of a zoom lens according to an embodiment. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 4 at the wide-angle end and when focused on infinity. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 4 at the telephoto end when focused on infinity. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 4 at the wide-angle end when focusing on a close distance. 10A to 10C are aberration diagrams illustrating various aberrations of the zoom lens according to Example 4 at the telephoto end when focusing on a close object. FIG. 1 is a block diagram illustrating an example of the configuration of an imaging device. 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; FIG. 2 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit. 1 is a configuration diagram showing an example of a schematic configuration of an endoscopic surgery system. FIG. 25 is a block diagram showing an example of the functional configuration of the camera head and the CCU shown in FIG. 24.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order.
0. Comparative Example 1. Basic Lens Configuration 2. Actions and Effects 3. Application Examples to Imaging Devices 4. Numerical Examples of Lenses 5. Application Examples 6. Other Embodiments

<0. Comparative Example>
The retrofocus zoom lenses proposed in Patent Documents 1 and 2 make it relatively easy to achieve an ultra-wide angle while maintaining a sufficient flange focal distance. However, in order to ensure a long flange focal distance at an ultra-wide angle, a strong positive refractive power is provided on the image plane side and a strong negative refractive power is provided on the object side, which results in insufficient aberration correction. Furthermore, for mirrorless camera systems, this refractive power arrangement places a constraint on miniaturization.

The zoom lens proposed in Patent Document 3 achieves a short overall optical length by not placing a strong positive refractive power in the lens group closest to the image plane, but the configuration within the lens group closest to the image plane is not optimal, resulting in insufficient aberration correction. As a result, the angle of view and aperture at the wide-angle end are not sufficiently wide.

Therefore, there is a demand for the development of a bright, high-performance zoom lens with a short overall optical length, as well as an imaging device equipped with such a zoom lens. In particular, there is a demand for the development of an ultra-wide-angle zoom lens with a short overall optical length and a bright maximum F-number that is suitable for mirrorless camera systems.

<1. Basic lens structure>
FIG. 1 shows a first configuration example of a zoom lens according to an embodiment of the present disclosure, which corresponds to the configuration of Example 1 described below. FIG. 6 shows a second configuration example of a zoom lens according to an embodiment, which corresponds to the configuration of Example 2 described below. FIG. 11 shows a third configuration example of a zoom lens according to an embodiment, which corresponds to the configuration of Example 3 described below. FIG. 16 shows a fourth configuration example of a zoom lens according to an embodiment, which corresponds to the configuration of Example 4 described below.

In Figure 1 and other figures, Z1 indicates the optical axis. An optical component such as a cover glass for protecting the image sensor may be disposed between the zoom lenses 1 to 4 according to the first to fourth configuration examples and the image plane IMG. In addition to the cover glass, various optical filters such as a low-pass filter or an infrared cut filter may also be disposed.

Below, the configuration of a zoom lens according to one embodiment of the present disclosure will be described, appropriately corresponding to zoom lenses 1 to 4 according to each configuration example shown in Figure 1 etc., but the technology according to the present disclosure is not limited to the configuration examples shown.

A zoom lens according to one embodiment is composed of, along the optical axis Z1, in order from the object side to the image plane side, a first group GP1, a second group GP2, an intermediate group GPm, and a final group GPr.

The first group GP1 has negative refractive power as a whole. The second group GP2 has positive refractive power as a whole.

The intermediate group GPm has one or more lens groups. The intermediate group GPm may be configured, for example, as in the first configuration example shown in FIG. 1, the second configuration example shown in FIG. 6, and the third configuration example shown in FIG. 11, where the lens group is composed of the third group GP3 and the fourth group GP4 (the zoom lens has a five-group configuration as a whole). The intermediate group GPm may also be configured, for example, as in the fourth configuration example shown in FIG. 16, where the lens group is composed of the third group GP3 (the zoom lens has a four-group configuration as a whole).

The final group GPr has three or more lens components and has negative refractive power overall. The final group GPr has three or more lens components: a first lens component La, a second lens component Lb, and a third lens component Lc. The first lens component La has negative refractive power and is located third from the image side. The second lens component Lb has negative refractive power and is located second from the image side. The third lens component Lc has positive refractive power and is located closest to the image side. Here, lens components refer to cemented lenses or single lenses.

When zooming from the wide-angle end to the telephoto end in a zoom lens according to one embodiment, each group moves along the optical axis Z1 so that the spacing between adjacent groups changes. Figures 1 and other figures show the lens arrangement at the wide-angle end and when focusing at infinity. Arrows in Figure 1 and other figures show an outline of the movement trajectory of each group when zooming from the wide-angle end to the telephoto end.

In addition, it is desirable that the zoom lens according to one embodiment further satisfies certain conditional expressions, etc., as described below.

<2. Actions and Effects>
Next, the operation and effects of the zoom lens according to the embodiment of the present disclosure will be described, along with a more desirable configuration of the zoom lens according to the embodiment of the present disclosure.
The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

The zoom lens according to one embodiment is configured with four or more groups overall, with each group optimized for its configuration, making it possible to realize a bright, high-performance zoom lens and imaging device with a short overall optical length. In particular, it makes it possible to realize an ultra-wide-angle zoom lens with a short overall optical length and a bright maximum F-number that is suitable for mirrorless camera systems.

In retrofocus optical systems, which are advantageous for wide-angle lenses, the group with negative refractive power is located closest to the object. In contrast, in a zoom lens according to one embodiment, the group with negative refractive power is also located closest to the image plane, which shortens the flange back and enables the overall optical length to be reduced.

In a zoom lens according to one embodiment, arranging a negative lens component closest to the image plane in the configuration of the final group GPr provides good symmetry with the first group GP1 and is advantageous for aberration correction, but it also increases the exit angle of off-axial rays toward the image plane. In the case of a digital camera in which an image sensor is located at the image plane IMG, this is not appropriate because a large angle of incidence on the image plane IMG reduces the light-receiving sensitivity of the image sensor, resulting in phenomena such as a decrease in the amount of received light and coloring. Therefore, in a zoom lens according to one embodiment, the third lens component Lc, which has positive refractive power, is located closest to the image plane to suppress an increase in the angle of incidence of rays on the image plane IMG, while the first lens component La and the second lens component Lb, which have negative refractive power, are located closer to the object than the third lens component Lc, thereby effectively strengthening the negative refractive power of the final group GPr.

In a zoom lens according to one embodiment, the second lens component Lb of the final group GPr is preferably a single lens with a concave surface facing the object side. In a zoom lens according to one embodiment, the height of off-axial rays passing through the second lens component Lb increases at the wide-angle end, so the above configuration makes it possible to efficiently correct distortion occurring in the first group GP1.

In a zoom lens according to one embodiment, it is desirable that the surface closest to the object of the second lens element Lb be formed with an aspherical surface that exhibits a greater amount of sag relative to the paraxial spherical surface at the periphery than at the center. In an ultra-wide-angle zoom lens, the heights of off-axial rays passing through the first lens element GP1 differ greatly between the wide-angle end and the telephoto end, resulting in greater distortion in the first lens element GP1 at the wide-angle end than at the telephoto end. In a zoom lens according to one embodiment, the difference in the heights of off-axial rays passing through the second lens element Lb between the wide-angle end and the telephoto end is utilized to form an aspherical surface that exhibits a greater amount of sag relative to the paraxial spherical surface at the periphery, enabling greater correction of distortion occurring in the first lens element GP1 at the periphery where the ray passing height is higher.

Furthermore, it is desirable that the zoom lens according to one embodiment satisfies the following conditional expressions (1) and (2), where the Abbe number of the third lens component Lc is vd and the partial dispersion ratio is ΘgF.
νd>70...(1)
0.015<ΔΘgF<0.1...(2)
however,
ΔΘgF=ΘgF-0.6483+0.001802×νd
Θgf=(ng-nF)/(nF-nC)
νd=(nd-1)/(nF-nC)
nd: refractive index of the third lens component Lc for the d-line, ng: refractive index of the third lens component Lc for the g-line, nF: refractive index of the third lens component Lc for the F-line, and nC: refractive index of the third lens component Lc for the C-line.

By constructing the third lens component Lc from a material that satisfies conditional expressions (1) and (2), it is possible to position the third lens component Lc with positive refractive power closest to the image plane without worsening chromatic aberration of magnification from the wide-angle end to the telephoto end.

It is also desirable that the zoom lens according to one embodiment satisfies the following conditional expression (3).
1.0<BW/fw<2.0...(3)
however,
BW: back focus at the wide-angle end fw: focal length of the entire system at the wide-angle end.

Conditional expression (3) is a conditional expression for setting the relationship between the focal length and back focus of the entire system at the wide-angle end. If the upper limit of conditional expression (3) is exceeded, the back focus will be too long relative to the focal length, resulting in an increase in the size of the entire system. If the lower limit of conditional expression (3) is exceeded, the focal length of the entire system at the wide-angle end cannot be made sufficiently small, resulting in an insufficient wide-angle. Alternatively, the lens closest to the image plane will be too close to the image plane IMG, making it difficult to arrange the mechanical components, which is undesirable.

It is more preferable to satisfy the following conditional expression (3A) in which the upper limit of conditional expression (3) is set to 1.5, since this allows the entire system to be made even more compact.
1.0<BW/fw<1.5...(3A)

Furthermore, from the viewpoint of widening the angle of view, it is more preferable to satisfy the following conditional expression (3B) in which the lower limit of conditional expression (3) is set to 1.1.
1.1<BW/fw<2.0...(3B)

In addition, in a zoom lens according to one embodiment, it is desirable that the second group GP2 moves along the optical axis direction when focusing from an object distance of infinity to a close distance, that the surface closest to the object side faces a convex surface toward the object side, and that the following conditional expression (4) be satisfied:
1.5<R2GF/fw<5...(4)
however,
R2GF: radius of curvature of the surface of the second lens unit GP2 closest to the object side; fw: focal length of the entire system at the wide-angle end.

Conditional expression (4) defines the relationship between the radius of curvature of the surface of the second group GP2 closest to the object and the focal length of the entire system at the wide-angle end. By making the surface of the second group GP2 closest to the object convex toward the object, fluctuations in the angle of incidence of light rays on the surface of the second group GP2 closest to the object during focusing are suppressed, thereby suppressing fluctuations in field curvature. If the lower limit of conditional expression (4) is exceeded, the radius of curvature of the surface of the second group GP2 closest to the object becomes too small, making it difficult to correct the spherical aberration and coma generated by that surface. If the upper limit of conditional expression (4) is exceeded, the positive refractive power of the second group GP2 becomes weak, increasing the amount of movement required of the second group GP2 during focusing, which undesirably leads to an increase in the size of the entire system.

From the viewpoint of aberration correction, it is more preferable to satisfy the following conditional expression (4A) in which the lower limit of conditional expression (4) is set to 1.8.
1.8<R2GF/fw<5...(4A)

Furthermore, from the viewpoint of miniaturization of the entire system, it is more preferable to satisfy the following conditional expression (4A) in which the upper limit of conditional expression (4) is set to 3.0.
1.5<R2GF/fw<3.0...(4B)

In a zoom lens according to an embodiment, it is desirable that the second group GP2 has, at the most object side, a lens that satisfies the following conditional expression (5).
Nd2G>1.8...(5)
however,
Nd2G: the refractive index for the d-line of the lens closest to the object in the second group GP2.

Below the lower limit of conditional expression (5), the radius of curvature of each surface of the second group GP2 becomes too small, making it difficult to correct the spherical aberration and coma that occur in the second group GP2. Above the upper limit of conditional expression (5), the specific gravity of the glass becomes too heavy, and if the second group GP2 is used as a focus lens group, the load on the actuator that drives the second group GP2 during focusing becomes undesirably large.

In addition, in a zoom lens according to one embodiment, it is desirable that the lens group in the intermediate group GPm located closest to the image plane has positive refractive power and moves toward the image plane when focusing at the telephoto end, where the object distance is from infinity to a close distance. It is also desirable that the lens group in the intermediate group GPm located closest to the image plane moves toward the image plane together with the second group GP2 during focusing. By having the lens group in the intermediate group GPm located closest to the image plane move together with the second group GP2 during focusing, it is possible to cancel out coma aberration that occurs when the second group GP2 is moved at the telephoto end, and to effectively correct coma aberration when the object distance is from infinity to a close distance.

(More desirable configuration)
It is desirable that the zoom lens according to the embodiment be further configured as follows.

In order to correct distortion and achieve a wide angle, it is desirable to place a negative meniscus lens with its concave surface facing the object side closest to the object in the first group GP1. Furthermore, it is even more desirable for this negative meniscus lens to be an aspherical lens, as this will enhance the effect of correcting distortion.

It is desirable for the first group GP1 to have at least two negative meniscus lenses arranged consecutively from the object side in order to suppress the occurrence of off-axis distortion and astigmatism.

It is desirable to place at least one negative lens with an Abbe number of 80 or more in the first group GP1, as this will enable appropriate correction of lateral chromatic aberration.

During focusing, it is desirable to move all or part of the second group GP2 and the intermediate group GPm at different movement ratios, as this can suppress fluctuations in field curvature and coma during focusing. To simplify the drive actuator during focusing, focusing may be performed at only one location of the second group GP2 or all or part of the intermediate group GPm.

3. Application example to imaging device
Next, a specific example of application of the zoom lens according to an embodiment of the present disclosure to an imaging device will be described.

Figure 21 shows an example configuration of an imaging device 100 that employs a zoom lens according to one embodiment. This imaging device 100 is, for example, a digital still camera, and includes a camera block 10, a camera signal processing unit 20, an image processing unit 30, an LCD (Liquid Crystal Display) 40, an R/W (Reader/Writer) 50, a CPU (Central Processing Unit) 60, an input unit 70, and a lens drive control unit 80.

The camera block 10 is responsible for the imaging function and has a zoom lens including an imaging lens 11, and an imaging element 12 such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor). The imaging element 12 converts the optical image formed by the imaging lens 11 into an electrical signal, and outputs an imaging signal (image signal) corresponding to the optical image. Zoom lenses 1 to 4 according to the configuration examples shown in Figures 1, 6, 11, and 16 can be used as the imaging lens 11.

The camera signal processing unit 20 performs various signal processing on the image signal output from the image sensor 12, such as analog-to-digital conversion, noise removal, image quality correction, and conversion to brightness and color difference signals.

The image processing unit 30 performs recording and playback processing of image signals, and is configured to perform compression encoding/decompression decoding processing of image signals based on a predetermined image data format, as well as conversion processing of data specifications such as resolution.

The LCD 40 has the function of displaying various data such as the user's operation status on the input unit 70 and captured images. The R/W 50 writes image data encoded by the image processing unit 30 to the memory card 1000 and reads image data recorded on the memory card 1000. The memory card 1000 is, for example, a semiconductor memory that can be inserted into and removed from a slot connected to the R/W 50.

The CPU 60 functions as a control processing unit that controls each circuit block provided in the imaging device 100, and controls each circuit block based on instruction input signals and the like from the input unit 70. The input unit 70 consists of various switches and the like that are operated as required by the user. The input unit 70 is composed of, for example, a shutter release button for operating the shutter and a selection switch for selecting an operating mode, and is configured to output instruction input signals to the CPU 60 in response to user operations. The lens drive control unit 80 controls the drive of the lenses arranged in the camera block 10, and is configured to control motors and the like (not shown) that drive each lens of the imaging lens 11 based on control signals from the CPU 60.

The operation of the imaging device 100 will be described below.
In a standby state for photographing, under the control of the CPU 60, an image signal photographed by the camera block 10 is output to the LCD 40 via the camera signal processing unit 20 and displayed as a camera-through image. Furthermore, when an instruction input signal for zooming or focusing is input from the input unit 70, the CPU 60 outputs a control signal to the lens drive control unit 80, and a predetermined lens of the imaging lens 11 moves under the control of the lens drive control unit 80.

When the shutter (not shown) of the camera block 10 is operated by an instruction input signal from the input unit 70, the captured image signal is output from the camera signal processing unit 20 to the image processing unit 30, where it is compressed and encoded and converted into digital data in a specified data format. The converted data is output to the R/W 50 and written to the memory card 1000.

Focusing is performed, for example, when the shutter release button on the input unit 70 is half-pressed or fully pressed for recording (photographing), by the lens drive control unit 80 moving a specified lens of the imaging lens 11 based on a control signal from the CPU 60.

When playing back image data recorded on memory card 1000, the R/W 50 reads out the specified image data from memory card 1000 in response to an operation on the input unit 70, and the image processing unit 30 performs an expansion/decoding process.The played-back image signal is then output to the LCD 40, and the played-back image is displayed.

In the above-described embodiment, an example was shown in which the imaging device was applied to a digital still camera, etc., but the application range of the imaging device is not limited to digital still cameras and can be applied to various other imaging devices. For example, it can be applied to digital single-lens reflex cameras, digital non-reflex cameras, digital video cameras, surveillance cameras, etc. It can also be widely used as the camera section of digital input/output devices such as mobile phones with built-in cameras and information terminals with built-in cameras. It can also be applied to cameras with interchangeable lenses.

<4. Numerical examples of lenses>
Next, specific numerical examples of the zoom lens according to an embodiment of the present disclosure will be described. Here, examples will be described in which specific numerical values are applied to the zoom lenses 1 to 4 according to the configuration examples shown in FIGS. 1, 6, 11, and 16.

The meanings of the symbols used in the tables and explanations below are as follows: "Si" indicates the number of the i-th surface, with the numbers increasing from the object-side. "ri" indicates the paraxial radius of curvature (mm) of the i-th surface. "di" indicates the axial distance (mm) between the i-th surface and the (i+1)-th surface. "ndi" indicates the refractive index at the d-line (wavelength 587.6 nm) of the material of the optical element that makes up the i-th surface. "νdi" indicates the Abbe number at the d-line of the material of the optical element that makes up the i-th surface. "φi" indicates the effective diameter (mm) of the i-th surface. A portion where the "ri" value is "∞" indicates a flat surface, an aperture surface, etc. "ASP" in the surface number (Si) column indicates that the surface is aspherical. "STO" in the surface number column indicates that an aperture stop (primary aperture stop) STO is located at the corresponding position. "FC1" in the surface number column indicates that a first flare cutter (first secondary aperture) FC1 is located at the corresponding position. "FC2" in the surface number column indicates that a second flare cutter (second secondary aperture) FC2 is located at the corresponding position. "OBJ" in the surface number column indicates that the corresponding surface is the object surface. "IMG" in the surface number column indicates that the corresponding surface is the image surface. "f" indicates the focal length of the entire system (unit: mm). "Fno" indicates the maximum aperture F-number. "ω" indicates the total angle of view (unit: °). "Y" indicates the image height (unit: mm). "L" indicates the total optical length (the distance on the optical axis from the surface closest to the object to the image surface IMG) (unit: mm).

Furthermore, some of the lenses used in each embodiment have aspherical lens surfaces. The aspherical shape is defined by the following formula. In the tables showing aspherical coefficients described below, "E-i" represents an exponential expression with base 10, i.e., "10 ^-i "; for example, "0.12345E-05" represents "0.12345×10 ^-5 ".

(Aspherical surface formula)
x=y ² c ² /(1+(1-(1+k)y ² c ² ) ^1/2 )+A4・y ⁴ +A6・y ⁶ +A8・y ⁸ +A10・y ¹⁰ +A12・y ¹² +A14・y ¹⁴
Here, the distance from the vertex of the lens surface in the optical axis direction (sag amount) is "x," the height in the direction perpendicular to the optical axis is "y," the paraxial curvature (the reciprocal of the radius of curvature) at the vertex of the lens surface is "c," and the conic constant is "k." A4, A6, A8, A10, A12, and A14 are the 4th-, 6th-, 8th-, 10th-, 12th-, and 14th-order aspheric coefficients, respectively.

[Configuration common to each embodiment]
Zoom lenses 1 to 4 to which the following Examples 1 to 4 are applied all have a configuration that satisfies the above-mentioned <1. Basic lens configuration>.

That is, each of the zoom lenses 1 to 4 is composed of, in order from the object side to the image plane side, a first group GP1, a second group GP2, an intermediate group GPm, and a final group GPr.

The first group GP1 has negative refractive power overall. The second group GP2 has positive refractive power overall. The intermediate group GPm has one or more lens groups.

The final group GPr has three or more lens components and has negative refractive power overall. The final group GPr has three or more lens components: a first lens component La, a second lens component Lb, and a third lens component Lc. The first lens component La has negative refractive power and is located third from the image side. The second lens component Lb has negative refractive power and is located second from the image side. The third lens component Lc has positive refractive power and is located closest to the image side.

When zooming from the wide-angle end to the telephoto end in any of zoom lenses 1 to 4, each group moves along the optical axis Z1 so that the distance between adjacent groups changes.

[Example 1]
Table 1 shows basic lens data for the zoom lens 1 according to Example 1 shown in FIG. 1 . Table 2 shows the initial surface and focal length (unit: mm) of each lens group in the zoom lens 1 according to Example 1. Table 3 shows the focal length f, F-number, total angle of view ω, image height Y, and total optical length L of the entire system of the zoom lens 1 according to Example 1. Table 3 also shows values for infinity focusing at the wide-angle end (Wide), intermediate focal length (Mid), and telephoto end (Tele). Table 4 also shows data on surface spacings that change during zooming in the zoom lens 1 according to Example 1 and data on effective diameters that change during zooming. Table 4 also shows values for the wide-angle end (Wide), intermediate focal length (Mid), and telephoto end (Tele) when the object distance (d0) is infinity and when the object distance is close. Table 5 shows the values of the coefficients representing the shape of the aspherical surface in the zoom lens 1 according to Example 1.

The zoom lens 1 of Example 1 is composed of, in order from the object side to the image plane side, a first group GP1 having negative refractive power, a second group GP2 having positive refractive power, a third group GP3 having positive refractive power, a fourth group GP4 having positive refractive power, and a fifth group GP5 having negative refractive power. In the zoom lens 1 of Example 1, the third group GP3 and the fourth group GP4 form the middle group GPm. The fifth group GP5 forms the final group GPr.

The first group GP1 is composed of, in order from the object side to the image plane side, lenses L11 to L15. Lenses L11 to L15 are each single lenses. Lenses L11 to L13 are each negative meniscus lenses with their convex surfaces facing the object side. Lens L14 is a negative biconcave lens. Lens L15 is a positive lens with its convex surface facing the object side. The two lenses closest to the object, L11 and L12, each have aspherical surfaces formed on both sides.

The second group GP2 is composed of, in order from the object side to the image plane side, a first flare cutter FC1, lens L21, and lens L22. Lens L21 is a negative lens, and lens L22 is a positive lens. Lenses L21 and L22 constitute a single lens component consisting of a negative lens and a positive lens cemented together, in order from the object side to the image plane side. The first flare cutter FC1 makes the optical aperture diameter smaller at the wide-angle end compared to the telephoto end, making it possible to effectively cut flare components around the periphery of the image at the wide-angle end.

The third group GP3 is composed of, in order from the object side to the image plane side, an aperture stop STO, lens L31, and lens L32. The aperture stop STO is a stop member that determines the F-number. Lens L31 is a single lens with negative refractive power. Lens L32 is a single lens with positive refractive power. Lens L32 has aspherical surfaces on both sides.

The fourth group GP4 is composed of, in order from the object side to the image plane side, lens L41 and lens L42. Lens L41 is a negative lens and lens L42 is a positive lens. Lenses L41 and L42 constitute a single lens component composed of a negative lens and a positive lens cemented together in order from the object side to the image plane side.

The fifth group GP5 is composed of, in order from the object side to the image plane side, a second flare cutter FC2 and lenses L51 to L56. Lens L51 is a positive lens, and lens L52 is a negative lens. Lenses L51 and L52, in order from the object side to the image plane side, consist of a positive lens and a negative lens cemented together to form a single lens component with negative refractive power. Lens L53 is a single lens with positive refractive power. The second flare cutter FC2 makes the optical aperture diameter smaller at the wide-angle end compared to the telephoto end, making it possible to effectively cut flare components around the periphery of the image at the wide-angle end.

Lens L54 is a biconcave single lens with negative refractive power. Lens L54 constitutes the first lens component La, which is located third from the image side. Lens L55 is a biconcave single lens with negative refractive power. Lens L55 constitutes the second lens component Lb, which is located second from the image side. Lens L56 is a biconvex single lens with positive refractive power. Lens L56 constitutes the third lens component Lc, which is located closest to the image side. Aspheric surfaces are formed on both sides of lens L55, which serves as the second lens component Lb. The aspheric shape imparted to the object-side surface of lens L55, which serves as the second lens component Lb, is added so that the amount of sag toward the object side is increased at the periphery of the lens relative to the paraxial spherical shape.

When zooming from the wide-angle end to the telephoto end in the zoom lens 1 of Example 1, the first group GP1 moves toward the image plane, and the second group GP2 to the fifth group GP5 move toward the object. At this time, the distance between the second group GP2 and the third group GP3 and the distance between the third group GP3 and the fourth group GP4 become smaller at the telephoto end, and the distance between the fourth group GP4 and the fifth group GP5 become larger at the telephoto end.

When focusing, the second group GP2 and the fourth group GP4 are movable groups. When focusing from infinity to a close object distance, the second group GP2 and the fourth group GP4 each move toward the image plane. Note that only one of the second group GP2 and the fourth group GP4 may be movable groups when focusing. For example, when focusing from infinity to a close object distance, only the second group GP2 may move toward the image plane. Alternatively, for example, when focusing from infinity to a close object distance, only the fourth group GP4 may move toward the object.

Aperture diaphragm St is located between the third and fourth lens groups GP3 and GP4. When zooming from the wide-angle end to the telephoto end, aperture diaphragm St moves toward the object side together with the third lens group GP3.

With the above configuration, the zoom lens 1 of Example 1 realizes an ultra-wide-angle zoom lens with a short overall optical length and a bright maximum F-number.

Figure 2 shows various aberrations of the zoom lens 1 of Example 1 at the wide-angle end and when focused at infinity. Figure 3 shows various aberrations of the zoom lens 1 of Example 1 at the telephoto end and when focused at infinity. Figure 4 shows various aberrations of the zoom lens 1 of Example 1 at the wide-angle end and when focused at a close distance. Figure 5 shows various aberrations of the zoom lens 1 of Example 1 at the telephoto end and when focused at a close distance. Figures 2 to 5 show various aberrations, including spherical aberration, astigmatism (curvature of field), distortion, and lateral chromatic aberration. In the spherical aberration diagram, the solid line indicates values at the d-line (587.56 nm), the dashed line indicates values at the g-line (435.84 nm), and the dashed-dotted line indicates values at the C-line (656.27 nm). In the astigmatism diagram, S indicates values at the sagittal image plane, and M indicates values at the meridional image plane. In the distortion diagram, values at the d-line are shown. The lateral chromatic aberration diagram shows the amount of lateral chromatic aberration for the g-line, and the same applies to the aberration diagrams for the other examples that follow.

As can be seen from each aberration diagram, the zoom lens 1 of Example 1 has excellent correction of various aberrations and has excellent imaging performance.

[Example 2]
Table 6 shows basic lens data for the zoom lens 2 according to Example 2 shown in FIG. 6 . Table 7 shows the initial surface and focal length (unit: mm) of each lens group in the zoom lens 2 according to Example 2. Table 8 shows the focal length f, F-number, total angle of view ω, image height Y, and total optical length L of the entire system of the zoom lens 2 according to Example 2. Table 8 also shows values for infinity focusing at the wide-angle end (Wide), intermediate focal length (Mid), and telephoto end (Tele). Table 9 also shows data on the surface spacing that changes during zooming in the zoom lens 2 according to Example 2, and data on the effective diameter that changes during zooming. Table 9 also shows values for the wide-angle end (Wide), intermediate focal length (Mid), and telephoto end (Tele) when the object distance (d0) is infinity and when it is close. Table 10 shows the values of the coefficients representing the shape of the aspherical surface in the zoom lens 2 according to Example 2.

The zoom lens 2 of Example 2 is composed of, in order from the object side to the image plane side, a first group GP1 having negative refractive power, a first flare cutter FC1, a second group GP2 having positive refractive power, a third group GP3 having positive refractive power, a fourth group GP4 having positive refractive power, and a fifth group GP5 having negative refractive power. In the zoom lens 2 of Example 2, the third group GP3 and the fourth group GP4 constitute the middle group GPm. The fifth group GP5 constitutes the final group GPr.

The first group GP1 is composed of, in order from the object side to the image plane side, lenses L11 to L15. Lenses L11 to L15 are each a single lens. Lenses L11 and L12 are each a negative meniscus lens with a convex surface facing the object side. Lenses L13 and L14 are each a negative lens with a biconcave shape. Lens L15 is a positive lens with a biconvex shape. The two lenses closest to the object, L11 and L12, each have aspherical surfaces formed on both sides.

A first flare cutter FC1 is positioned between the first lens group GP1 and the second lens group GP2, and when zooming from the wide-angle end to the telephoto end, the first flare cutter FC1 moves closer to the second lens group GP2. By positioning the first flare cutter FC1 away from the second lens group GP2 at the wide-angle end, it is possible to effectively cut flare components around the periphery of the image at the wide-angle end.

The second group GP2 is composed of, in order from the object side to the image plane side, lens L21 and lens L22. Lens L21 is a negative lens and lens L22 is a positive lens. Lenses L21 and L22 constitute a single lens component composed of a negative lens and a positive lens cemented together in order from the object side to the image plane side.

The third group GP3 is composed of, in order from the object side to the image plane side, an aperture stop STO, lens L31, and lens L32. The aperture stop STO is a stop member that determines the F-number. Lens L31 is a single lens with negative refractive power. Lens L32 is a single lens with positive refractive power. Lens L32 has aspherical surfaces on both sides.

The fourth group GP4 is composed of, in order from the object side to the image plane side, lens L41 and lens L42. Lens L41 is a negative lens and lens L42 is a positive lens. Lenses L41 and L42 constitute a single lens component composed of a negative lens and a positive lens cemented together in order from the object side to the image plane side.

The fifth group GP5 is composed of, in order from the object side to the image plane side, lenses L51 to L56. Lens L51 is a positive lens, and lens L52 is a negative lens. Lenses L51 and L52, in order from the object side to the image plane side, are cemented together to form a single lens component with negative refractive power. Lens L53 is a single lens with positive refractive power.

Lens L54 is a single lens with negative refractive power. Lens L54 is a negative meniscus lens with its concave surface facing the object side. Lens L54 constitutes the first lens component La, which is located third from the image side. Lens L55 is a single lens with negative refractive power. Lens L55 is a negative meniscus lens with its concave surface facing the object side. Lens L55 constitutes the second lens component Lb, which is located second from the image side. Lens L56 is a biconvex single lens with positive refractive power. Lens L56 constitutes the third lens component Lc, which is located closest to the image side. Both surfaces of lens L55, which serves as the second lens component Lb, are aspherical. The aspherical shape imparted to the object-side surface of lens L55, which serves as the second lens component Lb, is added so that the amount of sag toward the object side is increased at the lens periphery relative to the paraxial spherical shape.

When zooming from the wide-angle end to the telephoto end in the zoom lens 2 of Example 2, the first group GP1 moves toward the image plane, and the first flare cutter FC1 and the second group GP2 to the fifth group GP5 move toward the object. At this time, the third group GP3 and the fifth group GP5 move together without changing the distance between them when zooming from the wide-angle end to the telephoto end, and the second group GP2 and the fourth group GP4 move closer to the third group GP3.

When focusing, the second group GP2 and the fourth group GP4 are movable groups. When focusing from infinity to a close object distance, the second group GP2 and the fourth group GP4 each move toward the image plane. Note that only one of the second group GP2 and the fourth group GP4 may be movable groups when focusing. For example, when focusing from infinity to a close object distance, only the second group GP2 may move toward the image plane. Alternatively, for example, when focusing from infinity to a close object distance, only the fourth group GP4 may move toward the object.

The aperture stop St is located between the third and fourth lens groups GP3 and GP4. When zooming from the wide-angle end to the telephoto end, the aperture stop St moves toward the object side together with the third lens group GP3.

With the above configuration, the zoom lens 2 of Example 2 realizes an ultra-wide-angle zoom lens with a short overall optical length and a bright maximum F-number.

Figure 7 shows various aberrations of the zoom lens 2 according to Example 2 at the wide-angle end and when focused on infinity. Figure 8 shows various aberrations of the zoom lens 2 according to Example 2 at the telephoto end and when focused on infinity. Figure 9 shows various aberrations of the zoom lens 2 according to Example 2 at the wide-angle end and when focused on a close distance. Figure 10 shows various aberrations of the zoom lens 2 according to Example 2 at the telephoto end and when focused on a close distance.

As can be seen from each aberration diagram, the zoom lens 2 of Example 2 has excellent correction of various aberrations and has excellent imaging performance.

[Example 3]
Table 11 shows basic lens data for the zoom lens 3 according to Example 3 shown in FIG. 11 . Table 12 shows the first surface and focal length (unit: mm) of each lens group in the zoom lens 3 according to Example 3. Table 13 shows the focal length f, F-number, total angle of view ω, image height Y, and total optical length L of the entire system of the zoom lens 3 according to Example 3. Table 13 also shows values for infinity focusing at the wide-angle end (Wide), intermediate focal length (Mid), and telephoto end (Tele). Table 14 shows data on surface spacings that change during zooming in the zoom lens 3 according to Example 3 and data on effective diameters that change during zooming. Table 14 also shows values for the wide-angle end (Wide), intermediate focal length (Mid), and telephoto end (Tele) when the object distance (d0) is infinity and when the object distance is close. Table 15 shows the values of the coefficients representing the shape of the aspherical surface in the zoom lens 3 according to Example 3.

The zoom lens 3 of Example 3 is composed of, in order from the object side to the image plane side, a first group GP1 having negative refractive power, an aperture stop STO, a second group GP2 having positive refractive power, a third group GP3 having negative refractive power, a fourth group GP4 having positive refractive power, and a fifth group GP5 having negative refractive power. In the zoom lens 3 of Example 3, the third group GP3 and the fourth group GP4 form the middle group GPm. The fifth group GP5 forms the final group GPr.

The first group GP1 is composed of, in order from the object side to the image plane side, lenses L11 to L14. Lenses L11 to L14 are each a single lens. Lenses L11 and L12 are each a negative meniscus lens with a convex surface facing the object side. Lens L13 is a negative biconcave lens. Lens L14 is a positive biconvex lens. The two lenses closest to the object, L11 and L12, each have aspherical surfaces formed on both sides.

Between the first group GP1 and the second group GP2, an aperture stop STO, which is an aperture member that determines the F-number, is positioned, and when zooming from the wide-angle end to the telephoto end, the aperture stop STO moves closer to the second group GP2.

The second group GP2 is composed of, in order from the object side to the image plane side, lens L21 and lens L22. Lens L21 is a negative lens and lens L22 is a positive lens. Lenses L21 and L22 constitute a single lens component composed of a negative lens and a positive lens cemented together in order from the object side to the image plane side.

The third group GP3 is composed of, in order from the object side to the image plane side, a first flare cutter FC1, lens L31, and lens L32. Lens L31 is a single lens with positive refractive power. Lens L32 is a single lens with negative refractive power. Lens L31 has aspherical surfaces on both sides. The first flare cutter FC1 makes the optical aperture diameter smaller at the wide-angle end compared to the telephoto end, making it possible to effectively cut flare components in the peripheral areas of the image at the wide-angle end.

The fourth group GP4 is composed of, in order from the object side to the image plane side, lens L41 and lens L42. Lens L41 is a negative lens and lens L42 is a positive lens. Lenses L41 and L42 constitute a single lens component composed of a negative lens and a positive lens cemented together in order from the object side to the image plane side.

The fifth group GP5 is composed of, in order from the object side to the image plane side, a second flare cutter FC2 and lenses L51 to L55. The second flare cutter FC2 has a smaller optical aperture diameter at the telephoto end than at the wide-angle end, making it possible to effectively cut flare components around the periphery of the image at the telephoto end. Lens L51 is a single lens with positive refractive power.

Lens L52 is a positive lens, and lens L53 is a negative lens. Lenses L52 and L53 constitute a single lens component with negative refractive power, consisting of a positive lens and a negative lens cemented together in that order from the object side to the image side. Lenses L52 and L53 constitute the first lens component La, which is located third from the image side. Lens L54 is a biconcave single lens with negative refractive power. Lens L54 constitutes the second lens component Lb, which is located second from the image side. Lens L55 is a biconvex single lens with positive refractive power. Lens L55 constitutes the third lens component Lc, which is located closest to the image side. Both surfaces of lens L54, which serves as the second lens component Lb, are aspherical. The aspherical shape given to the object-side surface of the lens L54 as the second lens component Lb is added so that the amount of sag toward the object side increases in the lens periphery with respect to the paraxial spherical shape.

When zooming from the wide-angle end to the telephoto end in the zoom lens 3 of Example 3, the first group GP1 moves toward the image plane, and the aperture stop STO and the second group GP2 to the fifth group GP5 move toward the object. At this time, the third group GP3 and the fifth group GP5 move together without changing the distance between them when zooming from the wide-angle end to the telephoto end, and the second group GP2 and the fourth group GP4 move closer to the third group GP3.

When focusing, the second group GP2 and the fourth group GP4 are movable groups. When focusing from infinity to a close object distance, the second group GP2 and the fourth group GP4 each move toward the image plane. Note that only one of the second group GP2 and the fourth group GP4 may be movable groups when focusing. For example, when focusing from infinity to a close object distance, only the second group GP2 may move toward the image plane. Alternatively, for example, when focusing from infinity to a close object distance, only the fourth group GP4 may move toward the object.

With the above configuration, the zoom lens 3 of Example 3 realizes an ultra-wide-angle zoom lens with a short overall optical length and a bright maximum F-number.

Figure 12 shows various aberrations of the zoom lens 3 according to Example 3 at the wide-angle end and when focused at infinity. Figure 13 shows various aberrations of the zoom lens 3 according to Example 3 at the telephoto end and when focused at infinity. Figure 14 shows various aberrations of the zoom lens 3 according to Example 3 at the wide-angle end and when focused at a close distance. Figure 15 shows various aberrations of the zoom lens 3 according to Example 3 at the telephoto end and when focused at a close distance.

As can be seen from each aberration diagram, the zoom lens 3 of Example 3 has excellent correction of various aberrations and has excellent imaging performance.

[Example 4]
Table 16 shows basic lens data for the zoom lens 4 according to Example 4 shown in FIG. 16 . Table 17 shows the initial surface and focal length (unit: mm) of each lens group in the zoom lens 4 according to Example 4. Table 18 shows the focal length f, F-number, total angle of view ω, image height Y, and total optical length L of the entire system in the zoom lens 4 according to Example 4. Table 18 also shows values for infinity focusing at the wide-angle end (Wide), the intermediate focal length (Mid), and the telephoto end (Tele). Table 19 also shows data on the surface spacing that changes during zooming in the zoom lens 4 according to Example 4, and data on the effective diameter that changes during zooming. Table 19 also shows values for the wide-angle end (Wide), the intermediate focal length (Mid), and the telephoto end (Tele) when the object distance (d0) is infinity and when it is close. Table 20 shows the values of the coefficients representing the shape of the aspherical surface in the zoom lens 4 according to Example 4.

The zoom lens 4 of Example 4 is composed of, in order from the object side to the image plane side, a first group GP1 having negative refractive power, a first flare cutter FC1, a second group GP2 having positive refractive power, a third group GP3 having positive refractive power, and a fourth group GP4 having negative refractive power. In the zoom lens 4 of Example 4, the third group GP3 constitutes the middle group GPm. The fourth group GP4 constitutes the final group GPr.

The first group GP1 is composed of, in order from the object side to the image plane side, lenses L11 to L14. Lenses L11 to L14 are each a single lens. Lenses L11 and L12 are each a negative meniscus lens with a convex surface facing the object side. Lens L13 is a negative biconcave lens. Lens L14 is a positive lens with a convex surface facing the object side. Lens L11, which is closest to the object, and lens L13, which is third from the object side, each have aspherical surfaces formed on both sides.

A first flare cutter FC1 is positioned between the first lens group GP1 and the second lens group GP2, and when zooming from the wide-angle end to the telephoto end, the first flare cutter FC1 moves closer to the second lens group GP2. By positioning the first flare cutter FC1 away from the second lens group GP2 at the wide-angle end, it is possible to effectively cut flare components around the periphery of the image at the wide-angle end.

The second group GP2 is composed of, in order from the object side to the image plane side, an aperture stop STO and lenses L21 to L24. The aperture stop STO is a diaphragm member that determines the F-number. Lens L21 is a negative lens and lens L22 is a positive lens. Lenses L21 and L22, in order from the object side to the image plane side, are composed of a negative lens and a positive lens cemented together to form a single lens component with positive refractive power. Lens L23 is a negative lens and lens L24 is a positive lens. Lenses L23 and L24, in order from the object side to the image plane side, are composed of a negative lens and a positive lens cemented together to form a single lens component with negative refractive power.

The third group GP3 is composed of, in order from the object side to the image plane side, lens L31 and lens L32. Lens L31 is a negative lens and lens L32 is a positive lens. Lenses L31 and L32 constitute a single lens component composed of a negative lens and a positive lens cemented together in order from the object side to the image plane side.

The fourth group GP4 is composed of, in order from the object side to the image plane side, lenses L41 to L45. Lens L41 is a single lens with positive refractive power.

Lens L42 is a positive lens, and lens L43 is a negative lens. Lenses L42 and L43 constitute a single lens component with negative refractive power, consisting of a positive lens and a negative lens cemented together in that order from the object side to the image side. Lenses L42 and L43 constitute the first lens component La, which is located third from the image side. Lens L44 is a single lens with negative refractive power with its concave surface facing the object side. Lens L44 constitutes the second lens component Lb, which is located second from the image side. Lens L45 is a single lens with a biconvex shape and positive refractive power. Lens L45 constitutes the third lens component Lc, which is located closest to the image side. Both surfaces of lens L44, which serves as the second lens component Lb, are aspherical. The aspherical shape given to the object-side surface of the lens L44 as the second lens component Lb is added so that the amount of sag toward the object side increases in the lens periphery with respect to the paraxial spherical shape.

When zooming from the wide-angle end to the telephoto end in the zoom lens 4 of Example 4, the first group GP1 moves toward the image plane, and the first flare cutter FC1 and the second group GP2 to the fourth group GP4 move toward the object. At this time, the distance between the first flare cutter FC1 and the second group GP2 and the distance between the second group GP2 and the third group GP3 become smaller at the telephoto end, and the distance between the third group GP3 and the fourth group GP4 become wider at the telephoto end.

During focusing, the second and third groups GP2 and GP3, excluding the aperture diaphragm STO, are the movable groups. When focusing from infinity to a close object distance, the second and third groups GP2 and GP3, excluding the aperture diaphragm STO, each move toward the image plane. Note that during focusing, only one of the second and third groups GP2 and GP3, excluding the aperture diaphragm STO, may be the movable group. For example, when focusing from infinity to a close object distance, only the second group GP2, excluding the aperture diaphragm STO, may move toward the image plane. Alternatively, for example, when focusing from infinity to a close object distance, only the third group GP3 may move toward the object plane.

With the above configuration, the zoom lens 4 of Example 4 realizes an ultra-wide-angle zoom lens with a short overall optical length and a bright maximum F-number.

Figure 17 shows the various aberrations of the zoom lens 4 according to Example 4 at the wide-angle end and when focused on infinity. Figure 18 shows the various aberrations of the zoom lens 4 according to Example 4 at the telephoto end and when focused on infinity. Figure 19 shows the various aberrations of the zoom lens 4 according to Example 4 at the wide-angle end and when focused on a close distance. Figure 20 shows the various aberrations of the zoom lens 4 according to Example 4 at the telephoto end and when focused on a close distance.

As can be seen from each aberration diagram, the zoom lens 4 of Example 4 has excellent correction of various aberrations and has excellent imaging performance.

[Other Numerical Data for Each Example]
Table 21 shows the values for each of the above conditional expressions for each example. As can be seen from Table 21, the values for each example fall within the corresponding numerical range for each conditional expression.

<5. Application Examples>
[5.1 First Application Example]
The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, a robot, construction machinery, or agricultural machinery (tractor).

Figure 22 is a block diagram showing a schematic configuration example of a vehicle control system 7000, which is an example of a mobile object control system to which the technology disclosed herein can be applied. The vehicle control system 7000 includes multiple electronic control units connected via a communication network 7010. In the example shown in Figure 22, the vehicle control system 7000 includes a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an outside-vehicle information detection unit 7400, an inside-vehicle information detection unit 7500, and an integrated control unit 7600. The communication network 7010 connecting these multiple control units may be an in-vehicle communication network conforming to any standard, such as CAN (Controller Area Network), LIN (Local Interconnect Network), LAN (Local Area Network), or FlexRay (registered trademark).

Each control unit includes a microcomputer that performs arithmetic processing according to various programs, a memory unit that stores the programs executed by the microcomputer or parameters used in various calculations, and a drive circuit that drives various controlled devices. Each control unit includes a network I/F for communicating with other control units via the communication network 7010, as well as a communication I/F for communicating with devices or sensors inside and outside the vehicle via wired or wireless communication. Figure 22 illustrates the functional configuration of the integrated control unit 7600, including a microcomputer 7610, a general-purpose communication I/F 7620, a dedicated communication I/F 7630, a positioning unit 7640, a beacon receiving unit 7650, an in-vehicle device I/F 7660, an audio/video output unit 7670, an in-vehicle network I/F 7680, and a memory unit 7690. Other control units similarly include microcomputers, communication I/Fs, memory units, etc.

The drivetrain control unit 7100 controls the operation of devices related to the vehicle's drivetrain in accordance with various programs. For example, the drivetrain control unit 7100 functions as a control device for a driveforce generating device for generating vehicle driveforce, such as an internal combustion engine or drive motor, a driveforce transmission mechanism for transmitting driveforce to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating vehicle braking force. The drivetrain control unit 7100 may also function as a control device for an ABS (Antilock Brake System) or ESC (Electronic Stability Control), etc.

A vehicle state detection unit 7110 is connected to the drivetrain control unit 7100. The vehicle state detection unit 7110 includes at least one of the following: a gyro sensor that detects the angular velocity of the axial rotational motion of the vehicle body; an acceleration sensor that detects the acceleration of the vehicle; or a sensor for detecting the amount of accelerator pedal operation, the amount of brake pedal operation, the steering angle of the steering wheel, engine rotation speed, or wheel rotation speed, etc. The drivetrain control unit 7100 performs arithmetic processing using signals input from the vehicle state detection unit 7110, and controls the internal combustion engine, drive motor, electric power steering device, brake device, etc.

The body system control unit 7200 controls the operation of various devices installed in the vehicle body according to various programs. For example, the body system control unit 7200 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlights, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 7200. The body system control unit 7200 accepts these radio waves or signal inputs and controls the vehicle's door lock device, power window device, lamps, etc.

The battery control unit 7300 controls the secondary battery 7310, which is the power supply source for the drive motor, in accordance with various programs. For example, information such as battery temperature, battery output voltage, or remaining battery capacity is input to the battery control unit 7300 from a battery device equipped with the secondary battery 7310. The battery control unit 7300 performs calculations using these signals to control the temperature regulation of the secondary battery 7310 or to control cooling devices and other devices equipped in the battery device.

The outside vehicle information detection unit 7400 detects information outside the vehicle equipped with the vehicle control system 7000. For example, the outside vehicle information detection unit 7400 is connected to at least one of an imaging unit 7410 and an outside vehicle information detection unit 7420. The imaging unit 7410 includes at least one of a ToF (Time Of Flight) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. The outside vehicle information detection unit 7420 includes at least one of an environmental sensor for detecting the current weather or climate, or a surrounding information detection sensor for detecting other vehicles, obstacles, pedestrians, etc. around the vehicle equipped with the vehicle control system 7000.

The environmental sensor may be, for example, at least one of a raindrop sensor that detects rain, a fog sensor that detects fog, a sunshine sensor that detects the level of sunlight, and a snow sensor that detects snowfall. The surrounding information detection sensor may be at least one of an ultrasonic sensor, a radar device, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) device. The imaging unit 7410 and the outside vehicle information detection unit 7420 may each be provided as independent sensors or devices, or may be provided as a device that integrates multiple sensors or devices.

Here, Figure 23 shows an example of the installation locations of the imaging unit 7410 and the vehicle exterior information detection unit 7420. The imaging units 7910, 7912, 7914, 7916, and 7918 are installed, for example, at least one of the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 7900. The imaging unit 7910 installed on the front nose and the imaging unit 7918 installed on the top of the windshield inside the vehicle cabin mainly capture images of the front of the vehicle 7900. The imaging units 7912 and 7914 installed on the side mirrors mainly capture images of the sides of the vehicle 7900. The imaging unit 7916 installed on the rear bumper or back door mainly captures images of the rear of the vehicle 7900. The imaging unit 7918 provided on the upper part of the windshield inside the vehicle is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

Note that Figure 23 shows an example of the imaging ranges of each of the imaging units 7910, 7912, 7914, and 7916. Imaging range a indicates the imaging range of the imaging unit 7910 provided on the front nose, imaging ranges b and c indicate the imaging ranges of the imaging units 7912 and 7914 provided on the side mirrors, respectively, and imaging range d indicates the imaging range of the imaging unit 7916 provided on the rear bumper or tailgate. For example, by overlaying the image data captured by the imaging units 7910, 7912, 7914, and 7916, an overhead image of the vehicle 7900 viewed from above can be obtained.

External vehicle information detection units 7920, 7922, 7924, 7926, 7928, and 7930 provided on the front, rear, sides, corners, and above the windshield inside the vehicle cabin of the vehicle 7900 may be, for example, ultrasonic sensors or radar devices. External vehicle information detection units 7920, 7926, and 7930 provided on the front nose, rear bumper, back door, and above the windshield inside the vehicle cabin of the vehicle 7900 may be, for example, LIDAR devices. These external vehicle information detection units 7920 to 7930 are primarily used to detect preceding vehicles, pedestrians, obstacles, etc.

Returning to Figure 22, the explanation continues. The outside vehicle information detection unit 7400 causes the imaging unit 7410 to capture images outside the vehicle and receives the captured image data. The outside vehicle information detection unit 7400 also receives detection information from the connected outside vehicle information detection unit 7420. If the outside vehicle information detection unit 7420 is an ultrasonic sensor, radar device, or LIDAR device, the outside vehicle information detection unit 7400 emits ultrasonic waves or electromagnetic waves, etc., and receives information on the received reflected waves. Based on the received information, the outside vehicle information detection unit 7400 may perform object detection processing or distance detection processing for people, vehicles, obstacles, signs, or text on the road surface. Based on the received information, the outside vehicle information detection unit 7400 may also perform environmental recognition processing to recognize rainfall, fog, road conditions, etc. Based on the received information, the outside vehicle information detection unit 7400 may calculate the distance to an object outside the vehicle.

The outside vehicle information detection unit 7400 may also perform image recognition processing or distance detection processing to recognize people, vehicles, obstacles, signs, or text on the road surface based on the received image data. The outside vehicle information detection unit 7400 may perform processing such as distortion correction or alignment on the received image data, and may also synthesize image data captured by different imaging units 7410 to generate an overhead image or a panoramic image. The outside vehicle information detection unit 7400 may also perform viewpoint conversion processing using image data captured by different imaging units 7410.

The in-vehicle information detection unit 7500 detects information inside the vehicle. Connected to the in-vehicle information detection unit 7500 is, for example, a driver state detection unit 7510 that detects the driver's state. The driver state detection unit 7510 may include a camera that captures an image of the driver, a biosensor that detects the driver's biometric information, or a microphone that collects audio from within the vehicle cabin. The biosensor is provided, for example, on the seat or steering wheel, and detects the biometric information of a passenger sitting in the seat or the driver gripping the steering wheel. The in-vehicle information detection unit 7500 may calculate the driver's level of fatigue or concentration based on the detection information input from the driver state detection unit 7510, or may determine whether the driver is dozing off. The in-vehicle information detection unit 7500 may perform processing such as noise canceling on the collected audio signal.

The integrated control unit 7600 controls the overall operation of the vehicle control system 7000 in accordance with various programs. An input unit 7800 is connected to the integrated control unit 7600. The input unit 7800 may be implemented by a device that can be operated by an occupant, such as a touch panel, button, microphone, switch, or lever. Data obtained by voice recognition of voice input via a microphone may be input to the integrated control unit 7600. The input unit 7800 may be, for example, a remote control device that uses infrared or other radio waves, or an externally connected device such as a mobile phone or PDA (Personal Digital Assistant) that can operate the vehicle control system 7000. The input unit 7800 may be, for example, a camera, in which case the occupant can input information using gestures. Alternatively, data obtained by detecting the movement of a wearable device worn by the occupant may be input. Furthermore, the input unit 7800 may include, for example, an input control circuit that generates an input signal based on information input by the occupant using the input unit 7800 and outputs the signal to the integrated control unit 7600. Passengers and the like operate this input unit 7800 to input various data to the vehicle control system 7000 and to instruct processing operations.

The storage unit 7690 may include a ROM (Read Only Memory) that stores various programs executed by the microcomputer, and a RAM (Random Access Memory) that stores various parameters, calculation results, sensor values, etc. The storage unit 7690 may also be realized by a magnetic storage device such as an HDD (Hard Disc Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device.

The general-purpose communication I/F 7620 is a general-purpose communication I/F that mediates communication between various devices present in the external environment 7750. The general-purpose communication I/F 7620 may implement cellular communication protocols such as GSM (registered trademark) (Global System of Mobile communications), WiMAX (registered trademark), LTE (registered trademark) (Long Term Evolution) or LTE-Advanced (LTE-A), or other wireless communication protocols such as wireless LAN (also known as Wi-Fi (registered trademark)) and Bluetooth (registered trademark). The general-purpose communication I/F 7620 may connect to devices (e.g., application servers or control servers) present on an external network (e.g., the Internet, a cloud network, or an operator-specific network) via, for example, a base station or access point. In addition, the general-purpose communication I/F 7620 may connect to a terminal located near the vehicle (e.g., a terminal of a driver, pedestrian, or store, or an MTC (Machine Type Communication) terminal) using, for example, P2P (Peer To Peer) technology.

The dedicated communication I/F 7630 is a communication I/F that supports communication protocols designed for use in vehicles. The dedicated communication I/F 7630 may implement standard protocols such as WAVE (Wireless Access in Vehicle Environment), which is a combination of the lower layer IEEE 802.11p and the upper layer IEEE 1609, DSRC (Dedicated Short Range Communications), or a cellular communication protocol. The dedicated communication I/F 7630 typically performs V2X communication, a concept that includes one or more of vehicle-to-vehicle communication, vehicle-to-infrastructure communication, vehicle-to-home communication, and vehicle-to-pedestrian communication.

The positioning unit 7640 performs positioning by receiving, for example, GNSS signals from GNSS (Global Navigation Satellite System) satellites (e.g., GPS signals from GPS (Global Positioning System) satellites), and generates location information including the vehicle's latitude, longitude, and altitude. The positioning unit 7640 may determine the current location by exchanging signals with a wireless access point, or may obtain location information from a terminal with positioning capabilities, such as a mobile phone, PHS, or smartphone.

The beacon receiver 7650 receives, for example, radio waves or electromagnetic waves transmitted from radio stations installed on the road, and acquires information such as the current location, traffic congestion, road closures, and travel time. The functions of the beacon receiver 7650 may be included in the dedicated communication I/F 7630 described above.

The in-vehicle device I/F 7660 is a communication interface that mediates connections between the microcomputer 7610 and various in-vehicle devices 7760 present in the vehicle. The in-vehicle device I/F 7660 may establish a wireless connection using a wireless communication protocol such as wireless LAN, Bluetooth (registered trademark), NFC (Near Field Communication), or WUSB (Wireless USB). The in-vehicle device I/F 7660 may also establish a wired connection via a connection terminal (and, if necessary, a cable) not shown, such as USB (Universal Serial Bus), HDMI (High-Definition Multimedia Interface), or MHL (Mobile High-Definition Link). The in-vehicle device 7760 may include, for example, at least one of a mobile device or wearable device owned by the passenger, or an information device carried or installed in the vehicle. The in-vehicle device 7760 may also include a navigation device that searches for a route to a desired destination. The in-vehicle device I/F 7660 exchanges control signals or data signals with these in-vehicle devices 7760 .

The in-vehicle network I/F 7680 is an interface that mediates communication between the microcomputer 7610 and the communication network 7010. The in-vehicle network I/F 7680 sends and receives signals in accordance with a specified protocol supported by the communication network 7010.

The microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 in accordance with various programs based on information acquired via at least one of the general-purpose communication I/F 7620, dedicated communication I/F 7630, positioning unit 7640, beacon receiving unit 7650, in-vehicle device I/F 7660, and in-vehicle network I/F 7680. For example, the microcomputer 7610 may calculate control target values for the driving force generating device, steering mechanism, or braking device based on acquired information from inside and outside the vehicle, and output control commands to the drivetrain control unit 7100. For example, the microcomputer 7610 may perform cooperative control aimed at realizing the functions of an Advanced Driver Assistance System (ADAS), including vehicle collision avoidance or impact mitigation, following driving based on inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, and vehicle lane departure warning. In addition, the microcomputer 7610 may perform cooperative control for the purpose of autonomous driving, in which the vehicle travels autonomously without relying on driver operation, by controlling a driving force generating device, a steering mechanism, a braking device, etc. based on information acquired about the vehicle's surroundings.

The microcomputer 7610 may generate three-dimensional distance information between the vehicle and surrounding objects, such as structures and people, based on information acquired via at least one of the general-purpose communication I/F 7620, dedicated communication I/F 7630, positioning unit 7640, beacon receiving unit 7650, in-vehicle equipment I/F 7660, and in-vehicle network I/F 7680, and create local map information including information about the surrounding area of the vehicle's current location. Furthermore, the microcomputer 7610 may predict dangers, such as a vehicle collision, approaching pedestrians, or entering a closed road, based on the acquired information, and generate a warning signal. The warning signal may be, for example, a signal for generating a warning sound or turning on a warning lamp.

The audio/image output unit 7670 transmits at least one audio and/or image output signal to an output device capable of visually or audibly notifying vehicle occupants or the outside of the vehicle of information. In the example of FIG. 22 , an audio speaker 7710, a display unit 7720, and an instrument panel 7730 are illustrated as output devices. The display unit 7720 may include, for example, at least one of an on-board display and a head-up display. The display unit 7720 may have an AR (Augmented Reality) display function. The output device may also be other devices, such as headphones, a wearable device such as an eyeglass-type display worn by the occupant, a projector, or a lamp. When the output device is a display device, the display device visually displays the results obtained by various processes performed by the microcomputer 7610 or information received from other control units in various formats, such as text, images, tables, and graphs. When the output device is an audio output device, the audio output device converts audio signals consisting of reproduced audio data or acoustic data into analog signals and outputs them audibly.

In the example shown in FIG. 22, at least two control units connected via the communication network 7010 may be integrated into a single control unit. Alternatively, each control unit may be composed of multiple control units. Furthermore, the vehicle control system 7000 may include another control unit not shown. In addition, in the above description, some or all of the functions performed by one of the control units may be carried out by another control unit. In other words, as long as information is sent and received via the communication network 7010, predetermined calculation processing may be performed by one of the control units. Similarly, a sensor or device connected to one of the control units may be connected to another control unit, and multiple control units may send and receive detection information to each other via the communication network 7010.

In the vehicle control system 7000 described above, the zoom lens and imaging device of the present disclosure can be applied to the imaging unit 7410 and the imaging units 7910, 7912, 7914, 7916, and 7918.

[5.2 Second Application Example]
The technology disclosed herein may be applied to an endoscopic surgery system.

Figure 24 is a diagram showing an example of the general configuration of an endoscopic surgery system 5000 to which the technology disclosed herein can be applied. Figure 24 shows an operator (doctor) 5067 performing surgery on a patient 5071 on a patient bed 5069 using the endoscopic surgery system 5000. As shown, the endoscopic surgery system 5000 is composed of an endoscope 5001, other surgical tools 5017, a support arm device 5027 that supports the endoscope 5001, and a cart 5037 on which various devices for endoscopic surgery are mounted.

In endoscopic surgery, instead of cutting the abdominal wall and opening the abdomen, multiple punctures using tubular drilling instruments called trocars 5025a-5025d are inserted into the abdominal wall. The tube 5003 of the endoscope 5001 and other surgical instruments 5017 are then inserted into the body cavity of the patient 5071 through the trocars 5025a-5025d. In the illustrated example, the other surgical instruments 5017 inserted into the body cavity of the patient 5071 include an insufflation tube 5019, an energy treatment instrument 5021, and forceps 5023. The energy treatment instrument 5021 is a treatment instrument that uses high-frequency current or ultrasonic vibration to incise and dissect tissue, seal blood vessels, and perform other operations. However, the illustrated surgical instrument 5017 is merely an example, and various surgical instruments commonly used in endoscopic surgery, such as a surgeon or retractor, may be used as the surgical instrument 5017.

An image of the surgical site inside the body cavity of the patient 5071, captured by the endoscope 5001, is displayed on the display device 5041. While viewing the image of the surgical site displayed on the display device 5041 in real time, the surgeon 5067 performs treatment such as resecting the affected area using the energy treatment tool 5021 and forceps 5023. Although not shown, the insufflation tube 5019, energy treatment tool 5021, and forceps 5023 are supported by the surgeon 5067 or an assistant during surgery.

(Support arm device)
The support arm device 5027 includes an arm portion 5031 extending from a base portion 5029. In the example shown, the arm portion 5031 is composed of joints 5033a, 5033b, and 5033c and links 5035a and 5035b, and is driven under control of an arm control device 5045. The arm portion 5031 supports the endoscope 5001, and controls its position and orientation. This allows the endoscope 5001 to be stably fixed in position.

(Endoscopy)
The endoscope 5001 is composed of a lens barrel 5003, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 5071, and a camera head 5005 connected to the base end of the lens barrel 5003. In the example shown in the figure, the endoscope 5001 is configured as a so-called rigid lens barrel having a rigid lens barrel 5003, but the endoscope 5001 may also be configured as a so-called flexible lens barrel having a flexible lens barrel 5003.

An opening into which an objective lens is fitted is provided at the tip of the tube 5003. A light source device 5043 is connected to the endoscope 5001, and light generated by the light source device 5043 is guided to the tip of the tube by a light guide extending inside the tube 5003, and is then irradiated via the objective lens toward the object to be observed inside the body cavity of the patient 5071. The endoscope 5001 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

The camera head 5005 contains an optical system and an image sensor, and the optical system focuses reflected light (observation light) from the object being observed onto the image sensor. The image sensor photoelectrically converts the observation light to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. This image signal is sent to the camera control unit (CCU) 5039 as RAW data. The camera head 5005 is equipped with a function for adjusting the magnification and focal length by appropriately driving the optical system.

In addition, multiple image sensors may be provided in the camera head 5005, for example, to support stereoscopic vision (3D display). In this case, multiple relay optical systems are provided inside the lens barrel 5003 to guide observation light to each of the multiple image sensors.

(Various devices mounted on the cart)
The CCU 5039 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 5001 and the display device 5041. Specifically, the CCU 5039 performs various image processing, such as development processing (demosaic processing), on the image signal received from the camera head 5005 in order to display an image based on the image signal. The CCU 5039 provides the image signal after the image processing to the display device 5041. The CCU 5039 also transmits a control signal to the camera head 5005 to control its drive. The control signal may include information regarding imaging conditions, such as magnification and focal length.

Under the control of the CCU 5039, the display device 5041 displays an image based on an image signal that has been image processed by the CCU 5039. If the endoscope 5001 is compatible with high-resolution imaging, such as 4K (3840 horizontal pixels x 2160 vertical pixels) or 8K (7680 horizontal pixels x 4320 vertical pixels), and/or is compatible with 3D display, the display device 5041 may be capable of high-resolution display and/or 3D display, respectively. If the endoscope is compatible with high-resolution imaging, such as 4K or 8K, a display device 5041 with a size of 55 inches or larger can be used to achieve a more immersive experience. Furthermore, multiple display devices 5041 with different resolutions and sizes may be provided depending on the application.

The light source device 5043 is composed of a light source such as an LED (light emitting diode) and supplies illumination light to the endoscope 5001 when photographing the surgical site.

The arm control device 5045 is composed of a processor such as a CPU, and operates according to a predetermined program to control the drive of the arm portion 5031 of the support arm device 5027 according to a predetermined control method.

The input device 5047 is an input interface for the endoscopic surgery system 5000. The user can input various information and instructions to the endoscopic surgery system 5000 via the input device 5047. For example, the user inputs various information related to the surgery, such as the patient's physical information and information about the surgical procedure, via the input device 5047. In addition, for example, the user inputs via the input device 5047 instructions to drive the arm unit 5031, instructions to change the imaging conditions (type of irradiation light, magnification, focal length, etc.) of the endoscope 5001, instructions to drive the energy treatment tool 5021, etc.

The type of input device 5047 is not limited, and the input device 5047 may be any known input device. Examples of the input device 5047 that may be used include a mouse, keyboard, touch panel, switch, foot switch 5057, and/or lever. When a touch panel is used as the input device 5047, the touch panel may be provided on the display surface of the display device 5041.

Alternatively, the input device 5047 may be a device worn by the user, such as a glasses-type wearable device or an HMD (Head Mounted Display), and various inputs are made in response to the user's gestures and line of sight detected by these devices. The input device 5047 may also include a camera capable of detecting the user's movements, and various inputs are made in response to the user's gestures and line of sight detected from the image captured by the camera. The input device 5047 may also include a microphone capable of capturing the user's voice, and various inputs are made via voice via the microphone. In this way, the input device 5047 is configured to be able to input various information non-contact, allowing a user (e.g., the surgeon 5067) in a particularly clean area to operate equipment in an unclean area non-contact. Furthermore, the user can operate the equipment without removing their hands from the surgical tools they are holding, improving user convenience.

The treatment tool control device 5049 controls the operation of the energy treatment tool 5021 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 5051 inflates the body cavity of the patient 5071 through the insufflation tube 5019 in order to ensure a clear field of view for the endoscope 5001 and to ensure working space for the surgeon. The recorder 5053 is a device capable of recording various types of information related to the surgery. The printer 5055 is a device capable of printing various types of information related to the surgery in various formats, such as text, images, or graphs.

Below, the particularly characteristic configurations of the endoscopic surgery system 5000 are described in further detail.

(Support arm device)
The support arm device 5027 includes a base 5029 serving as a base and an arm 5031 extending from the base 5029. In the illustrated example, the arm 5031 is composed of multiple joints 5033a, 5033b, and 5033c and multiple links 5035a and 5035b connected by the joint 5033b. However, for simplicity, FIG. 24 illustrates a simplified configuration of the arm 5031. In practice, the shapes, number, and arrangement of the joints 5033a to 5033c and the links 5035a and 5035b, as well as the directions of the rotation axes of the joints 5033a to 5033c, can be appropriately set so that the arm 5031 has the desired degrees of freedom. For example, the arm 5031 can be preferably configured to have six or more degrees of freedom. This allows the endoscope 5001 to be moved freely within the movable range of the arm portion 5031, making it possible to insert the telescope tube 5003 of the endoscope 5001 into the body cavity of the patient 5071 from the desired direction.

Actuators are provided in the joints 5033a to 5033c, and the joints 5033a to 5033c are configured to rotate around a predetermined rotation axis when driven by the actuators. The drive of the actuators is controlled by the arm control device 5045, which controls the rotation angle of each joint 5033a to 5033c and controls the drive of the arm unit 5031. This makes it possible to control the position and attitude of the endoscope 5001. In this case, the arm control device 5045 can control the drive of the arm unit 5031 using various known control methods, such as force control or position control.

For example, the surgeon 5067 may perform appropriate operational input via the input device 5047 (including the foot switch 5057), which may then cause the arm control device 5045 to appropriately control the drive of the arm unit 5031 in accordance with the operational input, thereby controlling the position and posture of the endoscope 5001. Through this control, the endoscope 5001 at the tip of the arm unit 5031 can be moved from any position to any other position, and then fixedly supported at that position. The arm unit 5031 may also be operated in a so-called master-slave manner. In this case, the arm unit 5031 can be remotely controlled by the user via the input device 5047 installed in a location away from the operating room.

Furthermore, when force control is applied, the arm control device 5045 may perform so-called power assist control, in which the actuators of each joint 5033a to 5033c are driven so that the arm 5031 receives an external force from the user and moves smoothly in accordance with that external force. This allows the arm 5031 to be moved with a relatively light force when the user moves the arm 5031 while directly touching it. This makes it possible to move the endoscope 5001 more intuitively and with simpler operations, improving user convenience.

In general, during endoscopic surgery, the endoscope 5001 is supported by a doctor called a scopist. By using the support arm device 5027, the position of the endoscope 5001 can be fixed more reliably without manual intervention, enabling stable images of the surgical site to be obtained and enabling the surgery to be carried out smoothly.

The arm control device 5045 does not necessarily have to be provided on the cart 5037. Furthermore, the arm control device 5045 does not necessarily have to be a single device. For example, an arm control device 5045 may be provided on each of the joints 5033a to 5033c of the arm section 5031 of the support arm device 5027, and drive control of the arm section 5031 may be achieved by multiple arm control devices 5045 working together.

(Light source device)
The light source device 5043 supplies illumination light to the endoscope 5001 when photographing the surgical site. The light source device 5043 is composed of a white light source, such as an LED, a laser light source, or a combination of these. In this case, if the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, allowing the light source device 5043 to adjust the white balance of the captured image. In this case, it is also possible to time-share images corresponding to each RGB by irradiating the object of observation with laser light from each RGB laser light source and controlling the drive of the image sensor of the camera head 5005 in synchronization with the irradiation timing. This method allows color images to be obtained without providing a color filter to the image sensor.

The light source device 5043 may also be controlled to change the intensity of the light it outputs at predetermined time intervals. The operation of the image sensor of the camera head 5005 is controlled in synchronization with the timing of the change in light intensity to acquire images in a time-division manner, and by combining these images, it is possible to generate an image with a high dynamic range that is free of so-called blocked-up shadows and blown-out highlights.

The light source device 5043 may also be configured to provide light in a predetermined wavelength band compatible with special light observation. Special light observation, for example, utilizes the wavelength dependence of light absorption in body tissues to irradiate light with a narrower band than the light irradiated during normal observation (i.e., white light), thereby capturing high-contrast images of specific tissues, such as blood vessels on the surface of mucous membranes, known as narrow-band imaging. Alternatively, special light observation may involve fluorescence observation, in which images are obtained using fluorescence generated by irradiating excitation light. Fluorescence observation may involve irradiating excitation light onto body tissue and observing the fluorescence from the tissue (autofluorescence observation), or irradiating the tissue with excitation light corresponding to the fluorescent wavelength of a reagent such as indocyanine green (ICG) to obtain a fluorescent image. The light source device 5043 may be configured to provide narrow-band light and/or excitation light compatible with such special light observation.

(Camera head and CCU)
The functions of the camera head 5005 and the CCU 5039 of the endoscope 5001 will be described in more detail with reference to Fig. 25. Fig. 25 is a block diagram showing an example of the functional configuration of the camera head 5005 and the CCU 5039 shown in Fig. 24.

Referring to Figure 25, the camera head 5005 has, as its functions, a lens unit 5007, an imaging unit 5009, a drive unit 5011, a communication unit 5013, and a camera head control unit 5015. The CCU 5039 also has, as its functions, a communication unit 5059, an image processing unit 5061, and a control unit 5063. The camera head 5005 and the CCU 5039 are connected via a transmission cable 5065 to enable bidirectional communication.

First, the functional configuration of the camera head 5005 will be described. The lens unit 5007 is an optical system provided at the connection point with the lens barrel 5003. Observation light taken in from the tip of the lens barrel 5003 is guided to the camera head 5005 and enters the lens unit 5007. The lens unit 5007 is composed of a combination of multiple lenses, including a zoom lens and a focus lens. The optical characteristics of the lens unit 5007 are adjusted so that the observation light is focused on the light receiving surface of the image sensor of the imaging section 5009. In addition, the zoom lens and focus lens are configured so that their positions on the optical axis can be moved to adjust the magnification and focus of the captured image.

The imaging unit 5009 is composed of an imaging element and is arranged after the lens unit 5007. Observation light passing through the lens unit 5007 is focused on the light-receiving surface of the imaging element, and an image signal corresponding to the observed image is generated by photoelectric conversion. The image signal generated by the imaging unit 5009 is provided to the communication unit 5013.

The imaging element constituting the imaging unit 5009 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) type image sensor with a Bayer array capable of color imaging. The imaging element may also be capable of capturing high-resolution images, for example, 4K or higher. Obtaining high-resolution images of the surgical site allows the surgeon 5067 to grasp the state of the surgical site in more detail, enabling the surgery to proceed more smoothly.

The imaging element constituting the imaging unit 5009 is configured to have a pair of imaging elements for acquiring image signals for the right eye and left eye, respectively, corresponding to 3D display. 3D display allows the surgeon 5067 to more accurately grasp the depth of the biological tissue at the surgical site. Note that if the imaging unit 5009 is configured as a multi-plate type, multiple lens units 5007 are also provided corresponding to each imaging element.

Furthermore, the imaging unit 5009 does not necessarily have to be provided in the camera head 5005. For example, the imaging unit 5009 may be provided inside the lens barrel 5003, immediately after the objective lens.

The drive unit 5011 is composed of an actuator, and under the control of the camera head control unit 5015, moves the zoom lens and focus lens of the lens unit 5007 a predetermined distance along the optical axis. This allows the magnification and focus of the image captured by the imaging unit 5009 to be adjusted appropriately.

The communication unit 5013 is composed of a communication device for transmitting and receiving various information to and from the CCU 5039. The communication unit 5013 transmits image signals obtained from the imaging unit 5009 as RAW data to the CCU 5039 via the transmission cable 5065. At this time, in order to display the captured images of the surgical site with low latency, it is preferable that the image signals be transmitted via optical communication. During surgery, the surgeon 5067 performs the surgery while observing the condition of the affected area using the captured images, so for a safer and more reliable surgery, it is necessary that moving images of the surgical site be displayed as real-time as possible. When optical communication is used, the communication unit 5013 is provided with a photoelectric conversion module that converts electrical signals into optical signals. The image signals are converted into optical signals by the photoelectric conversion module and then transmitted to the CCU 5039 via the transmission cable 5065.

The communication unit 5013 also receives control signals from the CCU 5039 for controlling the operation of the camera head 5005. The control signals include information regarding the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value during imaging, and/or information specifying the magnification and focus of the captured image. The communication unit 5013 provides the received control signals to the camera head control unit 5015. Note that the control signals from the CCU 5039 may also be transmitted by optical communication. In this case, the communication unit 5013 is provided with a photoelectric conversion module that converts optical signals into electrical signals, and the control signals are converted into electrical signals by the photoelectric conversion module before being provided to the camera head control unit 5015.

The above-mentioned imaging conditions, such as frame rate, exposure value, magnification, and focus, are automatically set by the control unit 5063 of the CCU 5039 based on the acquired image signal. In other words, the endoscope 5001 is equipped with so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

The camera head control unit 5015 controls the driving of the camera head 5005 based on control signals received from the CCU 5039 via the communication unit 5013. For example, the camera head control unit 5015 controls the driving of the image sensor of the imaging unit 5009 based on information specifying the frame rate of the captured image and/or information specifying the exposure during image capture. Also, for example, the camera head control unit 5015 appropriately moves the zoom lens and focus lens of the lens unit 5007 via the drive unit 5011 based on information specifying the magnification and focus of the captured image. The camera head control unit 5015 may further have a function for storing information for identifying the lens barrel 5003 and the camera head 5005.

In addition, by arranging components such as the lens unit 5007 and the imaging unit 5009 in a sealed structure that is highly airtight and waterproof, the camera head 5005 can be made resistant to autoclave sterilization.

Next, the functional configuration of the CCU 5039 will be described. The communication unit 5059 is composed of a communication device for transmitting and receiving various information to and from the camera head 5005. The communication unit 5059 receives an image signal transmitted from the camera head 5005 via the transmission cable 5065. At this time, as described above, the image signal may be preferably transmitted by optical communication. In this case, to support optical communication, the communication unit 5059 is provided with an optoelectric conversion module that converts optical signals into electrical signals. The communication unit 5059 provides the image signal converted into an electrical signal to the image processing unit 5061.

In addition, the communication unit 5059 transmits a control signal to the camera head 5005 for controlling the operation of the camera head 5005. This control signal may also be transmitted by optical communication.

The image processing unit 5061 performs various image processing operations on the image signal, which is RAW data transmitted from the camera head 5005. Such image processing operations include various well-known signal processing operations, such as development processing, high-quality image processing (band enhancement processing, super-resolution processing, NR (Noise Reduction) processing, and/or image stabilization processing, etc.), and/or enlargement processing (electronic zoom processing). The image processing unit 5061 also performs detection processing on the image signal to perform AE, AF, and AWB.

The image processing unit 5061 is configured with a processor such as a CPU or GPU, and the processor operates in accordance with a predetermined program to perform the image processing and detection processing described above. If the image processing unit 5061 is configured with multiple GPUs, the image processing unit 5061 divides the information related to the image signal appropriately and performs image processing in parallel using these multiple GPUs.

The control unit 5063 performs various controls related to the imaging of the surgical site by the endoscope 5001 and the display of the captured images. For example, the control unit 5063 generates a control signal for controlling the operation of the camera head 5005. At this time, if the imaging conditions have been input by the user, the control unit 5063 generates a control signal based on the input by the user. Alternatively, if the endoscope 5001 is equipped with an AE function, an AF function, and an AWB function, the control unit 5063 appropriately calculates the optimal exposure value, focal length, and white balance according to the results of the detection processing by the image processing unit 5061, and generates a control signal.

The control unit 5063 also displays an image of the surgical site on the display device 5041 based on the image signal that has been image processed by the image processing unit 5061. At this time, the control unit 5063 recognizes various objects within the surgical site image using various image recognition technologies. For example, the control unit 5063 can recognize surgical tools such as forceps, specific biological parts, bleeding, mist generated when using the energy treatment tool 5021, and the like, by detecting the shape and color of the edges of objects contained in the surgical site image. When the control unit 5063 displays the image of the surgical site on the display device 5041, it uses the recognition results to superimpose various surgical support information onto the image of the surgical site. By superimposing the surgical support information and presenting it to the surgeon 5067, the surgery can be carried out more safely and reliably.

The transmission cable 5065 connecting the camera head 5005 and the CCU 5039 is an electrical signal cable for electrical signal communication, an optical fiber for optical communication, or a composite cable of these.

In the illustrated example, communication is performed wired using the transmission cable 5065, but communication between the camera head 5005 and the CCU 5039 may also be performed wirelessly. If communication between the two is performed wirelessly, there is no need to lay the transmission cable 5065 within the operating room, which can eliminate the situation where the transmission cable 5065 interferes with the movement of medical staff within the operating room.

The above describes an example of an endoscopic surgery system 5000 to which the technology disclosed herein can be applied. Note that while the endoscopic surgery system 5000 has been described here as an example, systems to which the technology disclosed herein can be applied are not limited to this example. For example, the technology disclosed herein may be applied to flexible endoscope systems for inspection or microsurgery systems.

The technology disclosed herein can be suitably applied to the camera head 5005 of the configurations described above. In particular, the zoom lens disclosed herein can be suitably applied to the lens unit 5007 of the camera head 5005.

6. Other embodiments
The technology according to the present disclosure is not limited to the above-described embodiments and examples, and various modifications are possible.

For example, the shapes and numerical values of each part shown in the above embodiment and examples are merely examples of concrete implementations for implementing this technology, and should not be interpreted in a limiting manner to the technical scope of this technology.

In addition, while the above embodiment and example have been described as consisting essentially of four or five groups overall, the configuration may also consist of six or more groups overall. Furthermore, the configuration may also include a lens that has substantially no refractive power.

For example, the present technology can be configured as follows.
According to the present technology having the following configuration, the overall configuration is four or more groups, and the configuration of each group is optimized, making it possible to realize a bright, high-performance zoom lens and an imaging device with a short overall optical length.

[1]
From the object side to the image plane side,
a first group having negative refractive power;
a second group having positive refractive power;
an intermediate group having one or more lens groups;
a final group having three or more lens components and having negative refractive power;
When zooming from the wide-angle end to the telephoto end, the spacing between adjacent groups changes,
In the final group, the three or more lens components are
a first lens component having negative refractive power and disposed third from the image plane side;
a second lens component having negative refractive power and disposed second closest to the image plane;
a third lens component having positive refractive power and disposed closest to the image plane side;
[2]
The zoom lens according to the above [1], wherein the second lens component is a single lens having a concave surface facing the object side.
[3]
The zoom lens according to the above [1] or [2], wherein an aspherical surface is formed on the surface of the second lens component closest to the object side, such that the amount of sag with respect to a paraxial spherical surface is larger in the periphery than in the center.
[4]
When the Abbe number of the third lens component is νd and the partial dispersion ratio is ΘgF,
The zoom lens according to any one of the above [1] to [3], which satisfies the following conditional expressions:
νd>70...(1)
0.015<ΔΘgF<0.1...(2)
however,
ΔΘgF=ΘgF-0.6483+0.001802×νd
Θgf=(ng-nF)/(nF-nC)
νd=(nd-1)/(nF-nC)
nd: refractive index of the third lens component for the d-line, ng: refractive index of the third lens component for the g-line, nF: refractive index of the third lens component for the F-line, and nC: refractive index of the third lens component for the C-line.
[5]
The zoom lens according to any one of the above [1] to [4], which satisfies the following conditional expressions:
1.0<BW/fw<2.0...(3)
however,
BW: back focus at the wide-angle end fw: focal length of the entire system at the wide-angle end.
[6]
The zoom lens according to any one of [1] to [5] above, wherein the second group moves along the optical axis direction when focusing from an object distance of infinity to a close distance, the surface closest to the object side is convex toward the object side, and the following conditional expression is satisfied:
1.5<R2GF/fw<5...(4)
however,
R2GF: radius of curvature of the surface of the second lens unit closest to the object side, and fw: focal length of the entire system at the wide-angle end.
[7]
The zoom lens according to any one of [1] to [6] above, wherein the second group has, closest to the object, a lens that satisfies the following conditional expression:
Nd2G>1.8...(5)
however,
Nd2G: the refractive index for the d-line of the lens in the second group closest to the object.
[8]
The zoom lens according to the above [6] or [7], wherein the lens group in the intermediate group that is arranged closest to the image plane has positive refractive power and moves toward the image plane when focusing at the telephoto end, where the object distance is from infinity to a close distance.
[9]
a zoom lens and an imaging element that outputs an imaging signal corresponding to an optical image formed by the zoom lens;
The zoom lens is
From the object side to the image plane side,
a first group having negative refractive power;
a second group having positive refractive power;
an intermediate group having one or more lens groups;
a final group having three or more lens components and having negative refractive power;
When zooming from the wide-angle end to the telephoto end, the spacing between adjacent groups changes,
In the final group, the three or more lens components are
a first lens component having negative refractive power and disposed third from the image plane side;
a second lens component having negative refractive power and disposed second closest to the image plane;
a third lens component having positive refractive power and disposed closest to the image plane side.
[10]
The zoom lens according to any one of the above [1] to [8], further comprising a lens having substantially no refractive power.
[11]
The imaging device according to [9] above, wherein the zoom lens further comprises a lens having substantially no refractive power.

This application claims priority based on Japanese Patent Application No. 2020-59846, filed on March 30, 2020, with the Japan Patent Office, the entire contents of which are incorporated herein by reference.

It is understood that those skilled in the art may conceive of various modifications, combinations, subcombinations, and variations depending on design requirements and other factors, and that these are within the scope of the appended claims and their equivalents.

Claims (7)

From the object side to the image plane side,
a first group having negative refractive power;
a second group having positive refractive power;
an intermediate group having one or more lens groups;
a final group having three or more lens components and having negative refractive power;
When zooming from the wide-angle end to the telephoto end, the spacing between adjacent groups changes,
In the final group, the three or more lens components are
a first lens component having negative refractive power and disposed third from the image plane side;
a second lens component having negative refractive power and disposed second closest to the image plane;
a third lens component having positive refractive power and disposed closest to the image plane ,
The second lens component is a single lens with a concave surface facing the object side.
Zoom lens. From the object side to the image plane side,
a first group having negative refractive power;
a second group having positive refractive power;
an intermediate group having one or more lens groups;
a final group having three or more lens components and negative refractive power;
It consists of
When zooming from the wide-angle end to the telephoto end, the spacing between adjacent groups changes,
In the final group, the three or more lens components are
a first lens component having negative refractive power and disposed third from the image plane side;
a second lens component having negative refractive power and disposed second closest to the image plane;
a third lens component having positive refractive power and disposed closest to the image plane;
Including,
The surface of the second lens component closest to the object side is formed with an aspherical surface such that the amount of sag with respect to the paraxial spherical surface is larger in the periphery than in the center.
Zoom lens. From the object side to the image plane side,
a first group having negative refractive power;
a second group having positive refractive power;
an intermediate group having one or more lens groups;
a final group having three or more lens components and negative refractive power;
It consists of
When zooming from the wide-angle end to the telephoto end, the spacing between adjacent groups changes,
In the final group, the three or more lens components are
a first lens component having negative refractive power and disposed third from the image plane side;
a second lens component having negative refractive power and disposed second closest to the image plane;
a third lens component having positive refractive power and disposed closest to the image plane;
Including,
When the Abbe number of the third lens component is νd and the partial dispersion ratio is ΘgF,
The following condition is satisfied:
Zoom lens.
νd>70...(1)
0.015<ΔΘgF<0.1...(2)
however,
ΔΘgF=ΘgF-0.6483+0.001802×νd
Θgf=(ng-nF)/(nF-nC)
νd=(nd-1)/(nF-nC)
nd: refractive index of the third lens component for the d-line, ng: refractive index of the third lens component for the g-line, nF: refractive index of the third lens component for the F-line, and nC: refractive index of the third lens component for the C-line. From the object side to the image plane side,
a first group having negative refractive power;
a second group having positive refractive power;
an intermediate group having one or more lens groups;
a final group having three or more lens components and negative refractive power;
It consists of
When zooming from the wide-angle end to the telephoto end, the spacing between adjacent groups changes,
In the final group, the three or more lens components are
a first lens component having negative refractive power and disposed third from the image plane side;
a second lens component having negative refractive power and disposed second closest to the image plane;
a third lens component having positive refractive power and disposed closest to the image plane;
Including,
the second lens unit moves along the optical axis direction during focusing from an object distance of infinity to a close distance, and the surface closest to the object side faces a convex surface toward the object side;
the lens group in the intermediate group that is located closest to the image plane has positive refractive power and moves toward the image plane when focusing from infinity to a close object distance at the telephoto end;
The following condition is satisfied:
Zoom lens.
1.5<R2GF/fw<5...(4)
however,
R2GF: radius of curvature of the surface of the second lens unit closest to the object side, and fw: focal length of the entire system at the wide-angle end. From the object side to the image plane side,
a first group having negative refractive power;
a second group having positive refractive power;
an intermediate group having one or more lens groups;
a final group having three or more lens components and negative refractive power;
It consists of
When zooming from the wide-angle end to the telephoto end, the spacing between adjacent groups changes,
In the final group, the three or more lens components are
a first lens component having negative refractive power and disposed third from the image plane side;
a second lens component having negative refractive power and disposed second closest to the image plane;
a third lens component having positive refractive power and disposed closest to the image plane;
Including,
The second lens unit has, at its most object side, a lens that satisfies the following condition:
Zoom lens.
Nd2G>1.8...(5)
however,
Nd2G: the refractive index for the d-line of the lens in the second group closest to the object. 6. The zoom lens according to claim 1, which satisfies the following condition:
1.0<BW/fw<2.0...(3)
however,
BW: back focus at the wide-angle end fw: focal length of the entire system at the wide-angle end. 6. A zoom lens according to claim 1 , wherein the zoom lens is an imaging element that outputs an imaging signal corresponding to an optical image formed by the zoom lens.
Imaging device.