JP7720170B2 - Lens unit, camera module, in-vehicle system and vehicle - Google Patents

Description

The present invention relates to a lens unit, camera module, in-vehicle system, and vehicle equipped with an in-vehicle system, which constitute an in-vehicle camera mounted in a vehicle such as an automobile.

In recent years, automobiles have been equipped with on-board cameras to assist with parking and prevent collisions through image recognition, and there have also been attempts to apply this to autonomous driving. Furthermore, camera modules for such on-board cameras generally include a lens unit that includes a lens group consisting of multiple lenses aligned along an optical axis, a barrel that houses and holds this lens group, and an aperture member that is positioned between at least one of the lenses in the lens group (see, for example, Patent Document 1).

In a lens unit, multiple lenses are typically stacked and assembled inside the barrel. Finally, a cap is attached to the object-side end of the barrel, or the object-side end of the barrel is crimped, thereby holding the lens group consisting of the stacked lenses in the optical axis direction within the barrel. In this case, particularly in vehicle-mounted cameras, the lens closest to the object that can be exposed to the outside is often made of glass, while the other inner lenses are often made of resin. In particular, when assembling a plastic lens inside a plastic barrel, the lens is typically lightly press-fit into the barrel with a predetermined diameter difference to prevent the lens from shifting due to vibration or impact, resulting in degradation of resolution or misalignment of the optical axis.

JP 2013-231993 A

In a lens unit where a plastic lens is press-fit into a plastic lens barrel, radially inward compressive stress constantly acts on the lens when the lens is assembled. Therefore, if there is a difference between the linear expansion coefficient (thermal expansion coefficient) of the lens barrel and that of the lens under such stress conditions—particularly in the typical case where the lens barrel is made of a material such as fiber-reinforced polyamide and the lens is made of a material such as unreinforced polycarbonate resin, resulting in a lens with a higher linear expansion coefficient and a lower flexural modulus—this difference causes the lens to expand in a high-temperature environment so that its outer diameter exceeds the inner diameter of the lens barrel. With nowhere for radial deformation to go, the lens's surface facing the optical axis undergoes permanent deformation (plastic deformation) in the optical axis direction. This type of lens deformation at high temperatures can adversely affect optical properties, such as making it impossible to achieve the desired resolution or causing focus shifts.

The present invention was made in consideration of the above circumstances, and aims to provide a lens unit, camera module, in-vehicle system, and vehicle that can reduce deformation in the optical axis direction of the lens due to differences in the linear expansion coefficients between the lens barrel and the lens.

In order to solve the above-mentioned problems, the present invention provides a lens unit including: a cylindrical lens barrel that forms an internal storage space for storing and holding lenses; and a lens group that is incorporated into the internal storage space of the lens barrel and that is made up of a plurality of lenses arranged along an optical axis,
at least one lens constituting the lens group is a resin lens formed of resin, the resin lens having a linear expansion coefficient greater than that of the lens barrel, and is incorporated into the inner accommodation space by press-fitting;
A buffer layer is interposed between the radially outer peripheral surface of the resin lens and the inner surface of the lens barrel, which absorbs and relieves the compressive stress acting on the resin lens toward the radially inward direction.

With the above-described configuration of the present invention, a buffer layer is interposed between the radially outer peripheral surface of the resin lens and the inner surface of the lens barrel. This absorbs and alleviates the compressive stress acting on the resin lens in a radially inward direction. Therefore, even if the resin lens, which is pressed into the internal storage space of the lens barrel and is constantly subjected to compressive stress in a radially inward direction and has a linear expansion coefficient greater than that of the lens barrel, attempts to expand and deform radially outward in a high-temperature environment, this deformation is at least partially absorbed by the buffer layer. Therefore, the resin lens is prevented from deforming so much in the radial direction that it becomes trapped and undergoes permanent deformation (plastic deformation) in the optical axis direction. In other words, deformation of the resin lens in the optical axis direction is suppressed (reduced), and the desired optical characteristics can be maintained even at high temperatures.

The buffer layer may be made of any material as long as it can relieve the radially inward compressive stress that causes deformation of the resin lens in the optical axis direction. However, to effectively and reliably relieve compressive stress, it is preferable that the buffer layer be made of a low-elasticity or soft material such as elastomer or rubber, and have a high heat resistance temperature (preferably 130°C or higher). In this case, the buffer layer may be separate from the lens barrel and the resin lens, or they may be integrated into the lens barrel. Furthermore, if the buffer layer is separate from the resin lens, it may be provided individually in correspondence with the portion of the lens barrel where the resin lens is located, or it may be provided over almost the entire inner surface of the lens barrel (for example, over the entire inner surface of the lens barrel except for the portion of the lens barrel where the lens closest to the object, such as a glass lens, is located). Furthermore, the thickness of the buffer layer is determined by the dimensions of the resin lens in the optical axis direction (thickness dimension) and radial dimension (outer diameter), the position of the resin lens within the lens barrel, the outer diameter of the lens barrel, etc., and may be set to, for example, 0.6 to 1.5 mm, and may maintain a constant dimension throughout, or may gradually increase or decrease (continuously or in steps) from the object side to the image side.

Furthermore, in the above-described configuration of the present invention, if the lens barrel is made of resin, it is preferable that the flexural modulus of the buffer layer be smaller than that of the lens barrel. In this case, it is even more preferable that the flexural modulus of the resin lens be smaller than that of the lens barrel, and that the flexural modulus of the buffer layer be smaller than that of the resin lens. In other words, it is even more preferable that the relationship of magnitude of the flexural moduli is flexural modulus of lens barrel > flexural modulus of resin lens > flexural modulus of buffer layer. This allows the buffer layer to reliably and sufficiently absorb and alleviate the compressive stress acting on the resin lens in the radially inward direction. Here, "made of resin" for a lens barrel means that resin is the main component (containing at least 20% by weight), and may also contain other materials such as glass filler.

In the above-described configuration of the present invention, the flexural modulus of the buffer layer is preferably 550 to 2500 MPa (N/mm ² ). This allows the deformation of the resin lens in the optical axis direction to be reduced by at least 2%, although this depends on the shape of the resin lens. The flexural modulus can be measured based on the JIS standard (JIS K7171).

Furthermore, in the above-described configuration of the present invention, the buffer layer may be integrated with the lens barrel or the resin lens. This allows for easy assembly of the lens into the lens barrel and ensures reliable and stable positioning of the buffer layer. The lens barrel and buffer layer can be integrated, for example, by insert molding. In this case, the lens barrel will have a two-layer structure consisting of a base layer and a buffer layer.

The present invention also provides a camera module having the aforementioned lens unit, an in-vehicle system having the camera module, and a vehicle equipped with the in-vehicle system. These camera modules, in-vehicle systems, and vehicles can achieve the same effects as the aforementioned lens unit.

According to this invention, a buffer layer is interposed between the radially outer peripheral surface of the resin lens and the inner surface of the lens barrel. This absorbs and relieves the compressive stress acting on the resin lens in the radially inward direction. This reduces deformation of the lens in the optical axis direction due to the difference in the linear expansion coefficient between the lens barrel and the lens.

1 is a schematic cross-sectional view (cross-sectional view along the optical axis) of a lens unit according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of FIG. 1 . 10 is a cross-sectional view showing an embodiment in which a buffer layer is provided on the inner surface of a lens barrel by insert molding, showing a state in which a buffer member that forms the buffer layer is attached to a movable-side mold. FIG. 4 is a cross-sectional view showing the state in which the mold is closed in the embodiment of FIG. 3 to define a cavity into which molten resin is poured. FIG. 10 is a table showing an example of material properties of a lens barrel, a resin lens, and a buffer layer. 10 is a table showing test results of the displacement amount of the center of the resin lens in the optical axis direction. FIG. 2 is a schematic cross-sectional view of a camera module having the lens unit of FIG. 1. 1 is a schematic diagram of a vehicle equipped with an in-vehicle system including a camera module according to an embodiment of the present invention. FIG. 9 is a block diagram showing the configuration of an imaging device that constitutes the in-vehicle system of FIG. 8 .

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present embodiments can realize highly reliable systems, particularly in sensing systems, and contribute to the development of resilient infrastructure. The target of the Sustainable Development Goals (SDGs) advocated by the United Nations is "9. Build resilient infrastructure, promote industry, innovation and infrastructure," which states, "9.1 Develop quality, reliable, sustainable and resilient infrastructure, including regional and transborder infrastructure, to support economic development and human well-being, with a focus on affordable and equitable access for all."
The lens unit of the present embodiment described below is particularly intended for use as a camera module for an in-vehicle camera or the like, and is fixedly installed on the exterior surface of the vehicle, with wiring leading into the vehicle and connected to a display or other device. Furthermore, hatching of multiple lenses is omitted in Figures 1 and 7.

Figure 1 shows a lens unit 11 according to one embodiment of the present invention. As shown, the lens unit 11 of this embodiment includes a cylindrical lens barrel 12, a plurality of lenses (e.g., five lenses consisting of a first lens 13, a second lens 14, a third lens 15, a fourth lens 16, and a fifth lens 17) arranged within a stepped inner storage space S of the lens barrel 12, and an aperture member 22. The aperture member is either an "aperture diaphragm" that limits the amount of transmitted light and determines the F-number, which is an indicator of brightness, or a "light-blocking diaphragm" that blocks light rays that cause ghosting or aberrations. An in-vehicle camera equipped with such a lens unit 11 includes the lens unit 11, a circuit board having an image sensor (not shown), and an installation member (not shown) for installing the circuit board in a vehicle such as an automobile. In this embodiment, the first lens 13, which can be exposed to the outside, is a glass lens, and the other inner lenses 14, 15, 16, and 17 are all resin lenses made of resin (plastic), but this is not limiting. Furthermore, the lens barrel 12 that houses these lenses 13, 14, 15, 16, and 17 is made of resin in this embodiment, but it may also be made of metal. Furthermore, the shape of the lens barrel and lenses, the number of lenses, etc. can be set as desired depending on the application, etc.

The multiple lenses 13, 14, 15, 16, and 17 fixed to and supported by the lens barrel 12 are arranged with their optical axes aligned, and the lenses 13, 14, 15, 16, and 17 are aligned along a single optical axis O to form a group of lenses L used for imaging. Of these, the fourth and fifth lenses 16 and 17, which are positioned closest to the image (the innermost part of the inner storage space S), are, for example, cemented lenses. Furthermore, the surfaces of these lenses 13, 14, 15, and 16 may be coated with an anti-reflection film, a hydrophilic film, a water-repellent film, or the like, as needed.

A crimped portion 23 is provided at the object-side end of the lens barrel 12 (the upper end in Figure 2) by crimping the end radially inward, and this crimped portion 23 secures the first lens 13, which is positioned closest to the object side of the lens group L, to the object-side end of the lens barrel 12.

Furthermore, an inner flange portion 24 having an opening with a diameter smaller than that of the fifth lens 17 is provided at the image-side end (the lower end in Figure 2) of the lens barrel 12. This inner flange portion 24 and the crimped portion 23 hold the multiple lenses 13, 14, 15, 16, and 17 that make up the lens group L and the aperture member 22 within the lens barrel 12.

The outer surface of the first lens 13, which is positioned closest to the object, has a tapered section with a reduced diameter on the image side of the lens 13. An O-ring 26 is provided as a sealing member at this tapered section, sealing the gap between the outer surface of the lens 13 and the inner surface of the lens barrel 12 at the object-side end of the lens barrel 12. This prevents water, dust, and other fine particles from entering the lens barrel 12 from the object-side end of the lens unit 11. The sealing member inserted between the first lens 13 and the lens barrel 12 is not limited to an O-ring, and can be any form of an annular body that can seal the gap between the first lens 13 and the lens barrel 12.

The inner and outer diameters of the lens barrel 12 decrease in stages from the object side to the image side. That is, the lens barrel 12 has a large-diameter section 12A that houses and holds the first and second lenses 13 and 14, and a small-diameter section 12B that houses and holds the third, second, and fifth lenses 15, 16, and 17. Corresponding to the stepped shape of the lens barrel 12, the outer diameters of the lenses 13, 14, 15, 16, and 17 decrease from the object side to the image side. An outer flange 25 is provided on the outer periphery of the lens barrel 12 in the shape of a brim and is used when installing the lens barrel 12 in an in-vehicle camera.

In addition, in this embodiment, the resin lenses 14, 15, 16, and 17 have a linear expansion coefficient greater than that of the lens barrel 12, and are press-fit into the internal storage space S of the lens barrel 12, except for the resin lens 16 on the object side of the cemented lens. As shown enlarged in Figure 2, a buffer layer 30 is interposed between the radially outer peripheral surfaces 14a, 15a, and 17a of the press-fit resin lenses 14, 15, and 17 and the internal surface 12a of the lens barrel 12, absorbing and alleviating the compressive stress acting radially inward on the resin lenses 14, 15, and 17.

5, the lens barrel 12 is formed from an anisotropic material made of fiber-reinforced polyamide (PA), which has a linear expansion coefficient of approximately 6×10 ⁻⁵ /°C in the flow direction and approximately 1×10 ⁻⁵ /°C in the perpendicular direction (perpendicular direction) (average of approximately 3.5×10 ⁻⁵ /°C), and has a heat resistance temperature of 130°C or higher. The resin lenses (plastic lenses) 14, 15, 16, and 17 are formed from an isotropic material made of polycarbonate (PC), cycloolefin polymer (COP), or the like, which has a linear expansion coefficient of approximately 6×10 ⁻⁵ /°C and a heat resistance temperature of 130°C or higher. The buffer layer 30 is formed from an isotropic material made of a low-elasticity material such as elastomer or rubber, or a soft material, which has a linear expansion coefficient of approximately 20×10 ⁻⁵ /°C and a heat resistance temperature of 130°C or higher. Here, the term "heat resistance temperature" refers to the higher of the deflection temperature under load and the glass transition temperature.

The buffer layer 30 is separate from the lenses 13-17 and the lens barrel 12, and may be provided individually to correspond to the internal portion of the lens barrel 12 where the resin lenses 14, 15, and 17 pressed into the internal storage space S are located. However, in this embodiment, the buffer layer 30 extends over almost the entire inner surface 12a of the lens barrel 12, specifically, over the entire inner surface 12a of the lens barrel 12 except for the internal portion of the lens barrel 12 where the first glass lens 13 closest to the object in the lens group L is located. In particular, the buffer layer 30 in this embodiment is formed from a roughly cylindrical buffer material with steps whose inner and outer diameters gradually decrease from the object side to the image side to conform to the shape of the inner surface 12a of the lens barrel 12. Its thickness is determined by the optical axis dimensions (thickness) and radial dimensions (outer diameter) of the resin lenses 14, 15, 16, and 17, the positions of the resin lenses 14, 15, 16, and 17 within the lens barrel 12, the outer diameter of the lens barrel, and other factors, and is set to, for example, 0.6 to 1.5 mm. In this embodiment, a constant dimension is maintained throughout. However, for example, the thickness of the buffer layer (buffer material) 30 may gradually (continuously or in steps) increase or decrease from the object side to the image side in accordance with the decrease in the outer diameter of the lenses 13-17 moving from the object side to the image plane side.

In this embodiment, the buffer layer 30 is separate from the lens 13-17 and the lens barrel 12, but the buffer layer 30 may also be integral with the lens barrel 12 or the lens 13-17. In particular, the integration of the lens barrel 12 and the buffer layer 30 can be achieved, for example, by insert molding. An example in which the buffer layer 30 is provided on the inner surface 12a of the lens barrel 12 by insert molding is shown in Figures 3 and 4. In this type of insert molding, as shown in Figure 3, a buffer member 30 prepared in advance as a buffer layer is attached to the movable mold part 40B of the mold 40. The movable mold part 40B is then assembled to the fixed mold part 40A, and the mold 40 is closed as shown in Figure 4 to define a cavity C into which molten resin is poured. In this state, molten resin is then poured into cavity C through gate 42 of fixed mold part 40A, and after hardening, movable mold part 40B is removed and the molded product is pushed out of fixed mold part 40A using an ejector pin (not shown) or similar, completing lens barrel 12, which has a two-layer structure consisting of a lens barrel base layer and buffer layer 30.

Furthermore, in this embodiment, the flexural modulus of buffer layer 30 is smaller than that of lens barrel 12, the flexural modulus of resin lenses 14, 15, 16, and 17 is smaller than that of lens barrel 12, and the flexural modulus of buffer layer 30 is smaller than that of resin lenses 14, 15, 16, and 17. In other words, the magnitude relationship of the flexural moduli satisfies the following relationship: flexural modulus of lens barrel 12 > flexural modulus of resin lenses 14, 15, 16, and 17 > flexural modulus of buffer layer 30. Specifically, in this embodiment, the flexural modulus of lens barrel 12 is set to 13,900 MPa (N/mm ² ), the flexural modulus of resin lenses 14, 15, 16, and 17 is set to 2,540 MPa, and the flexural modulus of buffer layer 30 is set to 550 to 2,500 MPa.

When the flexural modulus of the buffer layer 30 is set within this range, the amount of deformation of the resin lenses 14, 15, 16, and 17 in the optical axis direction can be reduced by at least 2%, depending on the shape of the resin lenses 14, 15, 16, and 17. Test results demonstrating this are shown in Figure 6. In this test, the lens barrel 12 was formed from a resin material (in this embodiment, "RENNY" (trademark) was used) in which 30% by weight of glass filler (GF) was mixed into the main component polyamide (PA), and the buffer layer 30 was formed from a highly heat-resistant elastomer (in this embodiment, "Hytrel 7247" (trademark) was used). Furthermore, the third lens 15 and fifth lens 17 were press-fitted into the lens barrel 12 without the buffer layer 30. The center of the object-side surface (positions A and C in Figure 1) and the center of the image-side (image-forming surface) surface of the lens barrel 12 were measured. The displacement in the optical axis direction at each of the positions B and D in FIG. 1 compared to when the lenses were not press-fitted was measured under temperature conditions of 125° C. and 25° C. (first row in the table in FIG. 6). The displacement in the optical axis direction at the center of the object-side surface (positions A and C in FIG. 1) and the center of the image-side (image plane side) surface (positions B and D in FIG. 1) of the third lens 15 and the fifth lens 17 press-fitted into the lens barrel 12 with the buffer layer 30 was measured under temperature conditions of 125° C. and 25° C. (second row in the table in FIG. 6). The percentage values (%) shown below the displacement amounts are values when the displacement amounts of the respective lenses 15 and 17 in the lens barrel 12 without the buffer layer 30 are set to 100%, and the negative signs indicate a decrease in the displacement amounts. For example, at the center (position D) of the image-side surface of the fifth lens 17 in a lens barrel 12 without a buffer layer 30, a certain displacement is shown at a temperature of 25°C. If this is taken as 100% (the displacement when there is no buffer layer 30 is taken as 100%), then at the center (position D) of the image-side surface of the fifth lens 17 in a lens barrel 12 with a buffer layer 30, the displacement is reduced by 69.3% at a temperature of 25°C (the minus sign indicates a reduction in displacement).

In this test, the flexural modulus of the lens barrel 12 was 13,900 N/ ^mm² , the flexural modulus of the buffer layer 30 was 550 N/ ^mm² , and the thickness of the buffer layer 30 was 0.7 mm. Furthermore, for the lens barrel 12 including the buffer layer 30, simulations were also performed in which the flexural modulus of the buffer layer 30 was changed to 1,000 N/ ^mm² , 1,500 N/ ^mm² , and 2,500 N/ ^mm² , and the displacement amounts at the centers of the object-side and image-side surfaces of the third lens 15 and the fifth lens 17 were calculated at 125°C and 25°C (third row of the table).

As can be seen from the results in Figure 6, when the buffer layer 30 is included, displacement of the resin lens in the optical axis direction is suppressed compared to when the buffer layer 30 is not included, at least within the flexural modulus range of 550 to 2500 MPa, and the suppression effect becomes greater the smaller the flexural modulus (the softer the layer).

Figure 7 shows a schematic cross-sectional view of a camera module 300 of this embodiment, which has a lens unit 11 configured as described above. As shown in the figure, this camera module 300 is configured to include the lens unit 11 of Figure 2 to which the filter 100 is attached.

The camera module 300 includes an upper case (camera case) 301, which is an exterior component, and a mount (base) 302 that holds the lens unit 11. The camera module 300 also includes a sealing member 303 and a package sensor (image sensor) 304.

The upper case 301 is a member that exposes the object-side end of the lens unit 11 and covers the other parts. The mount 302 is disposed inside the upper case 301 and has a female thread 302a that screws into the male thread 11a of the lens unit 11. The sealing member 303 is a member that is interposed between the inner surface of the upper case 301 and the outer peripheral surface 12b of the lens barrel 12 of the lens unit 11, and is a member that maintains airtightness inside the upper case 301.

The package sensor 304 is located inside the mount 302 and is positioned to receive the image of the object formed by the lens unit 11. The package sensor 304 is equipped with a CCD, CMOS, or other device, and converts the light that is collected and reaches it through the lens unit 11 into an electrical signal. The converted electrical signal is then converted into analog data or digital data, which are components of the image data captured by the camera.

8 is a schematic diagram of a vehicle 40 equipped with an in-vehicle system including an imaging device 50 including the camera module 300 of FIG. 7. As shown, the imaging device 50 can be mounted on the vehicle 40, and FIG. 8 is an example of an arrangement illustrating the mounting position of the imaging device 50 on the vehicle 40. The imaging device 50 mounted on the vehicle 40 can also be called an in-vehicle camera and can be installed in various locations on the vehicle 40. For example, the first imaging device 50a may be installed on or near the front bumper as a camera that monitors the front of the vehicle 40 while it is traveling. The second imaging device 50b, which monitors the front, may be installed near the inner rearview mirror inside the vehicle 40. The third imaging device 50c may be installed on the dashboard or in the instrument panel as a camera that monitors the driver's driving status. The fourth imaging device 50d may be installed at the rear of the vehicle 40 to monitor the rear of the vehicle 40. The imaging devices 50a and 50b can be called front cameras. The third imaging device 50c can be called an in-camera. The fourth imaging device 50d can be called a rear camera. The imaging device 50 is not limited to these, and can include imaging devices installed in various positions, such as a left side camera that captures images of the left rear side and a right side camera that captures images of the right rear side.

The image signal of the image captured by the imaging device 50 may be output to an information processing device 42 and/or a display device 43 within the vehicle 40. Together with the imaging device 50, the information processing device 42 and the display device 43 constitute an in-vehicle system. The information processing device 42 within the vehicle 40 includes a device that processes the image signal acquired by the imaging device 50, recognizes the image, and assists the driver in driving. Examples of the information processing device 42 include, but are not limited to, a navigation system, a collision damage mitigation braking system, a vehicle-to-vehicle distance control device, and a lane departure warning system. The display device 43 displays the image processed and output by the information processing device 42, but can also receive the image signal directly from the imaging device 50. The display device 43 may be, but is not limited to, a liquid crystal display (LCD), an organic electroluminescence (EL) display, or an inorganic EL display. The display device 43 can display to the driver the image signal output from the imaging device 50, which captures images from positions difficult for the driver to view, such as a rear camera.

Figure 9 shows the configuration of an imaging device that makes up the in-vehicle system of Figure 8. As shown, the imaging device 50 according to one embodiment includes a control unit 52, a storage unit 54, and the camera module 300 shown in Figure 7.

The control unit 52 controls the camera module 300 and processes the electrical signals output from the image sensor 304 of the camera module 300. The control unit 52 may be configured as a processor, for example. The control unit 52 may also include one or more processors. The processor may include a general-purpose processor that loads a specific program to execute a specific function, and a dedicated processor specialized for a specific process. The dedicated processor may include an application-specific integrated circuit (IC). An application-specific IC is also called an application-specific integrated circuit (ASIC). The processor may include a programmable logic device. A programmable logic device is also called a programmable logic device (PLD). A PLD may include an FPGA (field-programmable gate array). The control unit 52 may be either a system-on-a-chip (SoC) or a system-in-a-package (SiP) in which one or more processors work together.

The memory unit 54 stores various information or parameters related to the operation of the imaging device 50. The memory unit 54 may be composed of, for example, a semiconductor memory. The memory unit 54 may function as a work memory for the control unit 52. The memory unit 54 may store captured images. The memory unit 54 may store various parameters, etc., used by the control unit 52 to perform detection processing based on the captured images. The memory unit 54 may be included in the control unit 52.

As described above, the camera module 300 captures an image of a subject formed through the lens unit 11 using the image sensor 304 and outputs the captured image. The image captured by the camera module 300 is also referred to as a captured image.

The imaging element 304 may be configured, for example, as a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device). The imaging element 304 has an imaging surface on which multiple pixels are arranged. Each pixel outputs a signal specified by a current or voltage according to the amount of incident light. The signal output by each pixel is also referred to as imaging data.

The imaging data may be read by the camera module 300 for all pixels and imported into the control unit 52 as a captured image. A captured image read out for all pixels is also referred to as a maximum captured image. The imaging data may be read by the camera module 300 for some pixels and imported as a captured image. In other words, the imaging data may be read out from pixels within a predetermined capture range. The imaging data read out from pixels within the predetermined capture range may be imported as a captured image. The predetermined capture range may be set by the control unit 52. The camera module 300 may acquire the predetermined capture range from the control unit 52. The image sensor 304 may capture an image of a predetermined capture range from the subject image formed via the lens unit 11.

As described above, according to this embodiment, a buffer layer 30 is interposed between the radially outer peripheral surfaces 14a, 15a, and 17a of the resin lenses 14, 15, and 17 and the inner surface 12a of the lens barrel 12. This buffer layer 30 absorbs and relieves the compressive stress acting radially inward on the resin lenses 14, 15, and 17. Therefore, even if the resin lenses 14, 15, and 17, which are pressed into the inner storage space S of the lens barrel 12 and are constantly subjected to compressive stress acting radially inward and have a linear expansion coefficient greater than that of the lens barrel 12, attempt to expand and deform radially outward in a high-temperature environment, this deformation is at least partially absorbed by the buffer layer 30. Therefore, the resin lenses 14, 15, and 17 are prevented from deforming so much in the radial direction that they become trapped and undergo permanent deformation (plastic deformation) in the optical axis direction. In other words, deformation of the resin lenses 14, 15, and 17 in the optical axis direction is suppressed (reduced), thereby maintaining the desired optical characteristics even at high temperatures.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. For example, the shapes of the lenses, lens barrels, etc. are not limited to those of the above-described embodiments. Furthermore, without departing from the spirit of the invention, some or all of the above-described embodiments may be combined, or part of the configuration may be omitted from one of the above-described embodiments.

REFERENCE SIGNS LIST 11 Lens unit 12 Lens barrel 12a Inner surface 14, 15, 16, 17, 18 Resin lenses 14a, 15a, 17a Radially outer peripheral surface 30 Buffer layer 40 Vehicle 42 Information processing device (processing device)
43 Display device 50 Imaging device 52 Control unit 300 Camera module 304 Imaging element L Lens group S Inner storage space

Claims (8)

A lens unit comprising: a cylindrical lens barrel that forms an internal storage space for storing and holding lenses; and a lens group that is incorporated into the internal storage space of the lens barrel and that is composed of a plurality of lenses arranged along an optical axis,
at least two lenses constituting the lens group are resin lenses formed of resin, the resin lenses have a linear expansion coefficient greater than that of the lens barrel, and are press-fitted into the inner housing space so as to be stacked one on top of the other ;
a buffer layer is interposed between a radially outer peripheral surface of the resin lens and an inner surface of the lens barrel, the buffer layer absorbing and alleviating compressive stress acting on the resin lens toward the radially inner side;
A lens unit characterized in that the buffer layer extends continuously over the entire inner surface of the lens barrel on which all of the stacked resin lenses are located, so as to conform to the shape of the inner surface. The lens unit described in claim 1, characterized in that the lens barrel is made of resin, and the flexural modulus of the buffer layer is smaller than the flexural modulus of the lens barrel. The lens unit described in claim 2, characterized in that the flexural modulus of the resin lens is smaller than that of the lens barrel, and the flexural modulus of the buffer layer is smaller than that of the resin lens. A lens unit described in any one of claims 1 to 3, characterized in that the buffer layer has a flexural modulus of elasticity of 550 to 2500 MPa. A lens unit described in any one of claims 1 to 4, characterized in that the buffer layer is integral with the lens barrel or the resin lens. A camera module comprising the lens unit described in any one of claims 1 to 5 and an image sensor that converts light focused through the lens group of the lens unit into an electrical signal. An in-vehicle system mounted on a vehicle,
an imaging device comprising: the camera module according to claim 6; and a control unit that controls the camera module and processes an electrical signal output from the imaging element of the camera module;
a processing device that processes an image signal acquired by the imaging device;
a display device that displays an image processed and output by the processing device;
An in-vehicle system comprising: A vehicle equipped with the on-board system described in claim 7.