JP5757699B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus.

In the conventional digital still camera and moving image camera, the following AF methods (1) and (2) are realized.
(1) There is an apparatus in which an optical system and a sensor for AF are arranged separately from an image sensor. A typical one is a phase difference type AF used in a single-lens reflex camera. The advantage of this method is that it can solve the parallax problem by using the light flux that has passed through the taking lens, detect the focus shift with a single distance measurement signal, and focus the taking lens on the subject. The time to focus can be shortened.

  On the other hand, in this method, it is necessary to arrange an optical path switching or dividing means between the photographing lens and the image sensor, and further, an AF optical system is required between the optical path switching or dividing means and the AF sensor. . This demerit causes an increase in size in terms of (a) securing a space for the optical path switching means and (b) securing a space for the AF optical system and the dedicated sensor. Furthermore, when (c) the optical path switching means is arranged, a time lag due to the switching mechanism and switching occurs, and (d) when the optical path dividing means is arranged, a light quantity loss due to the optical path division occurs.

  (2) There is also an AF method that uses the output of the image sensor itself. A typical example is contrast AF used in so-called compact digital cameras and moving picture cameras (video cameras). The merit of this method is that the imaging device and the AF sensor are integrated, which is advantageous in terms of space and that there are few constituent members.

  On the other hand, this method has a demerit that it is necessary to compare a plurality of distance measurement signals and that it takes time to focus due to wobbling. Furthermore, in moving image shooting, blurring of an image due to wobbling is shot, and image quality is impaired. This tendency becomes more prominent as the pixel becomes higher.

  Furthermore, in recent years, interchangeable lens cameras have been released on the premise of electronic viewfinders that do not require a quick return mirror and roof prism, as opposed to single lens reflex cameras equipped with an optical viewfinder using a quick return mirror and roof prism. Both still image shooting and moving image shooting are required to have high image quality. Particularly in such a camera, there is a demand for AF that has the merits of the methods (1) and (2) and solves the disadvantages.

JP 2000-156823 A JP 2009-44636 A JP 2009-44637 A Japanese Patent Laid-Open No. 2008-40087 JP 2009-157043 A

  In response to the above problems, the solid-state imaging device disclosed in Patent Document 1 is configured to output a signal for ranging from a part of the pixels of the imaging element, and the ranging pixels are arranged on the photoelectric conversion unit. And a light shielding film layer having a specific opening portion disposed between the microlens and the photoelectric conversion portion. The photoelectric conversion unit includes a first pixel in which the opening of the light shielding film layer is biased with respect to the optical center of the microlens, and an opening of the light shielding film layer in a direction opposite to the first photoelectric conversion cell with respect to the optical center of the microlens. And a second pixel having a bias to the image, and focusing is performed using phase difference information of output signals of the two types of pixels. A plurality of pixels that output a signal for forming an image signal are arranged around the distance measurement pixels. The image information of the position of the ranging pixels is interpolated using the peripheral image forming pixels, thereby forming an image.

  In the solid-state imaging device of Patent Document 1, the principle of distance measurement of phase difference AF using pupil division used in a conventional single-lens reflex camera is adopted, and the aperture efficiency of the distance measurement pixels is about half or less than that of the image forming pixels. Therefore, the ranging pixels cannot be used as image forming pixels. For this reason, the image information at the position of the ranging pixel is interpolated using the image information at the surrounding image forming pixels. However, if image information is obtained by performing pixel interpolation, the image quality deteriorates. Furthermore, if the accuracy of distance measurement is improved or the distance measurement area is improved, the density of distance measurement pixels increases, and the image quality deteriorates greatly.

  In the imaging devices of Patent Document 2 and Patent Document 3, the distance measurement pixel gain is increased in order to correct the difference in aperture efficiency between the distance measurement pixel and the image formation pixel, and the output of the distance measurement pixel is image-formed. It is proposed to be used for However, this proposal has problems that signal processing becomes complicated and image quality deterioration such as noise occurs due to strong gain increase of the ranging pixels. Furthermore, when ranging accuracy and a ranging area are improved, the density of ranging pixels increases and image quality deteriorates greatly. In the imaging devices of Patent Document 2 and Patent Document 3, it is necessary to switch whether or not information from the ranging pixel is used for image formation based on the frequency characteristics of the subject, and the color information from the ranging pixel. Can't get. Furthermore, in this imaging apparatus, it is premised that the distance measurement pixels are equal to or less than a certain ratio with respect to the image formation pixels.

  In the imaging device of Patent Document 4, as a configuration of the ranging pixels, a plurality of photoelectric conversion units are arranged so that light beams obtained by dividing the pupil can be independently received. According to this configuration, at the time of image formation, by adding outputs from a plurality of photoelectric conversion units configured in one distance measurement pixel, the difference in aperture efficiency from the image formation pixel is substantially reduced. It is possible to alleviate the problem of image quality degradation that has been a problem in Patent Documents 1 to 3. On the other hand, since this configuration is substantially the same as increasing the number of pixels of the image sensor, the configuration becomes difficult, and in addition, an addition means is added for the ranging pixels. Becomes more complex and the impact on image quality is also a challenge.

  In the imaging apparatus of Patent Document 5, it has been proposed to provide polarization characteristics to the aperture position of the photographic lens and the imaging pixels. However, if the degree of polarization is increased, only about 1/4 or less of the amount of light incident on the photographing lens can be received, and measures such as increasing the exposure time are required.

  The present invention has been made in view of the above, and has an output signal from an image sensor, and has a ranging performance comparable to that of phase difference AF, and the configuration of the image sensor is relatively simple, and image quality deterioration is reduced. The purpose is to propose a small number of imaging devices.

In order to solve the above-described problems and achieve the object, an imaging apparatus according to the present invention is an imaging apparatus in which a photographic lens can be attached or a photographic lens is fixed, and a plurality of two-dimensionally arranged imaging apparatuses. And an on-chip lens disposed in front of the photoelectric conversion surface corresponding to the plurality of pixels, each of the plurality of pixels receiving one or more light beams having a predetermined incident angle range Dimming means disposed at the front of the photoelectric conversion surface of each pixel set so as to dimm a luminous flux having a predetermined incident angle range, and having at least two types of pixel sets formed by the pixels; has a phase difference amount calculation unit for calculating a phase difference amount by comparing the output signals from the two pixel sets each other, an image processing unit that performs image formation from the pixel information, a light-reducing means, on Chip lens Is arranged near, are discretely arranged so as to cover a part of the on-chip lens, and is substantially light absorbing ND filter not to lose color information, to satisfy the following conditional expression (3) It is characterized by.
50% ≦ T ≦ 85% (3)
Where T is the transmittance.

  In the imaging device according to the present invention, it is preferable that an image forming pixel is included in any of the pixel sets.

  In the imaging device according to the present invention, an on-chip lens is provided in front of the photoelectric conversion surface of the pixel, and the dimming means is discretely arranged so as to cover a part of the on-chip lens in the vicinity of the on-chip lens. It is preferable.

  In the imaging device according to the present invention, the pixel set includes a pixel set R in which the right half of the on-chip lens is covered by a dimming unit and a pixel set L in which the left half is covered by two types of pixels. The output signal from the set is preferably an output signal in the horizontal direction of the pixel set L and the pixel set R.

  In the imaging apparatus according to the present invention, as the pixel set, the pixel set R in which the right half of the on-chip lens is covered by the dimming means, the pixel set L in which the left half is covered, and the on-chip lens by the dimming means. The pixel set U in which the upper half is covered and the pixel set S in which the lower half is covered, and output signals from the two types of pixel sets are output in the horizontal direction of the pixel set L and the pixel set R. A signal or an output signal in the vertical direction of the pixel set U and the pixel set S is preferable.

  In the imaging device according to the present invention, it is preferable that a color filter is disposed in front of the photoelectric conversion surface of the pixel.

  In the imaging device according to the present invention, it is preferable that the pixels on which the color filters are arranged form a pixel set.

  The image pickup apparatus according to the present invention has an effect of ranging performance comparable to that of the phase difference AF, the structure of the image pickup device is relatively simple, and there is little deterioration in image quality.

1 is a diagram illustrating a basic configuration of an imaging apparatus according to a first embodiment. It is the top view which shows the structure of the light reduction means which concerns on 1st Embodiment, and is the figure which looked at the light reduction means from the direction of the optical axis. It is a top view which shows the example of arrangement | positioning of the pixel of the image pick-up element which concerns on 1st Embodiment, and is the figure which looked at the image pick-up element from the direction of the optical axis. It is sectional drawing which shows the structure of the pixel in 1st Embodiment. It is a top view which shows the structure of the light reduction means which concerns on the 1st modification of 1st Embodiment, and is the figure which looked at the light reduction means from the direction of the optical axis. It is a top view which shows the structure of the light reduction means which concerns on the 2nd modification of 1st Embodiment, and is the figure which looked at the light reduction means from the direction of the optical axis. It is a top view which shows the position of the area gravity center of the light quantity of the light beam which injects into a 1st pixel group in the light reduction means which concerns on the 2nd modification of 1st Embodiment. It is a top view which shows an area gravity center and an area gravity center equivalent position in the light reduction means which concerns on the 2nd modification of 1st Embodiment. It is a top view which shows notionally the pixel arrangement | positioning in the image pick-up element which concerns on the 3rd modification of 1st Embodiment. FIG. 10 is a plan view conceptually showing an arrangement of color filters corresponding to FIG. 9. It is a figure which shows the basic composition of the imaging device which concerns on 2nd Embodiment. It is the top view which looked at the image sensor and dimming means concerning a 2nd embodiment from the direction of the optical axis. It is the top view which looked at the image sensor and dimming means concerning the 1st modification of a 2nd embodiment from the direction of the optical axis. It is sectional drawing which shows the structure of the pixel in 2nd Embodiment. It is sectional drawing which shows the structure of the pixel which concerns on the 2nd modification of 2nd Embodiment. It is the top view which looked at the pixel of the image sensor concerning the 1st comparative example, and the light reduction means from the direction of the optical axis in piles. It is the top view which looked at the pixel and dimming means of the image sensor concerning the 2nd comparative example from the direction of the optical axis. It is the top view which looked at the pixel of the image sensor which concerns on a 3rd comparative example, and the light reduction means from the direction of the optical axis. It is a figure which shows arrangement | positioning of the pixel of the image pick-up element in 2nd Embodiment, and a light reduction means, Comprising: It is the top view seen from the direction of the optical axis. It is sectional drawing which shows the structural example of the pixel which concerns on the 3rd modification of 2nd Embodiment. It is sectional drawing which shows the structural example of the pixel which concerns on the 4th modification of 2nd Embodiment. It is a block diagram which shows the structure of a camera system (imaging system) of an interchangeable lens in more detail.

Hereinafter, embodiments of an imaging apparatus according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following embodiment.
First, prior to the description of the embodiment, the operation and effect of the imaging apparatus according to the present invention will be described.

  An imaging device according to the present invention is an imaging device in which a photographic lens can be attached or a photographic lens is fixed, and includes an imaging device having a plurality of pixels arranged two-dimensionally, and the plurality of pixels are , Each having at least two types of pixel sets formed by one or more pixels that receive a light beam having a predetermined incident angle range, and dimming the light beam having the predetermined incident angle range, Dimming means arranged in front of the photoelectric conversion surface of the pixel set, a phase difference amount calculating unit for calculating a phase difference amount by comparing output signals from at least two types of pixel sets, and pixel information An image processing unit that performs image formation.

  According to this configuration, by using light reduction means instead of light shielding, each pixel can obtain a sufficient amount of light for image formation, and the output level of each pixel becomes uniform, so that deterioration of image quality can be prevented.

In the imaging device according to the present invention, it is preferable that an image forming pixel is included in any of the pixel sets.
According to this configuration, the pixel set functioning as the focus detection pixel also serves as the image forming pixel, so that the ranging accuracy can be improved without degrading the image quality.

In the imaging apparatus according to the present invention, the dimming unit is disposed in the photographing lens, and the dimming unit includes a transmission region, a first polarizing region, and a second polarizing region, and the first polarizing region The second polarization region is a region for dimming or shielding light beams whose polarization directions are different from each other by 90 degrees, and has a first pixel set and a second pixel set as a pixel set to form a first pixel set. The pixel receives A% of the light beam in the polarization direction to be dimmed or shielded in the first polarization region, receives B% of the light beam in the polarization direction to be dimmed or shielded in the second polarization region, and receives the second pixel set. The pixel to be formed receives B% of the light beam in the polarization direction to be dimmed or shielded in the first polarization region, and receives A% of the light beam in the polarization direction to be dimmed or shielded in the second polarization region. It is preferable that the conditional expression (1) is satisfied.
0 <A / B <1 (1)

  According to this configuration, a light beam having a predetermined incident angle range that passes through the first polarizing region and the second polarizing region by a combination of the first polarizing region and the second polarizing region, which is disposed in the vicinity of the predetermined virtual position. Are incident on the respective pixel sets under different dimming effects. That is, the pixels forming the first pixel set receive light in a state where the light flux from the first polarization region is further dimmed, and the pixels forming the second pixel set are further reduced in light flux from the second polarization region. Receive light in the By arranging the transmission region, it becomes easy to secure the entire light amount. In conditional expression (1), if there is an incident light beam, the first pixel set and the second pixel set can receive light regardless of the polarization direction by keeping the lower limit value, and depending on the polarization direction by keeping the upper limit value. The light quantity ratio between the first pixel group and the second pixel group can be changed.

  Here, it is desirable that the first polarization region and the second polarization region are arranged symmetrically with respect to the optical axis and have the same size. This makes it easier to obtain phase difference information from the output signals from the first pixel set and the second pixel set.

In the image pickup apparatus according to the present invention, the dimming means is disposed in the photographic lens, the dimming means has a first polarizing region and a second polarizing region, and the first polarizing region and the second polarizing region are polarized light. This is a region through which light beams of directions different from each other by 90 degrees pass, and has a first pixel set and a second pixel set as a pixel set, and the pixels forming the first pixel set are dimmed in the first polarization region Alternatively, A% of the light beam in the polarization direction to be shielded is received, B% of the light beam in the polarization direction to be dimmed or shielded is received in the second polarization region, and the pixels forming the second pixel set are in the first polarization region. When B% of the light beam in the polarization direction to be dimmed or shielded is received and A% of the light beam in the polarization direction to be dimmed or shielded is received in the second polarization region, the following conditional expression (2) is satisfied. Is preferred.
0.1 <(B−A) / (A + B) <0.5 (2)

According to this configuration, a light beam having a predetermined incident angle range that passes through the first polarizing region and the second polarizing region by a combination of the first polarizing region and the second polarizing region, which is disposed in the vicinity of the predetermined virtual position. Are incident on the respective pixel sets under different dimming effects. That is, the pixels forming the first pixel set receive light in a state where the light flux from the first polarization region is further dimmed, and the pixels forming the second pixel set are further reduced in light flux from the second polarization region. Receive light in the Satisfying conditional expression (2) makes it easy to secure the entire light amount.
By keeping the lower limit value of conditional expression (3), the light quantity ratio between the first pixel group and the second pixel group is secured by the polarization direction, and the whole light quantity is secured by keeping the upper limit value of conditional expression (3). .

  Desirably, the first polarizing region and the second polarizing region are arranged symmetrically with respect to the optical axis and have the same size. This makes it easier to obtain phase difference information from the output signals from the first pixel set and the second pixel set.

  In the imaging device according to the present invention, the pixel has an on-chip lens in front of the photoelectric conversion surface of the pixel, and the dimming unit is discretely arranged to cover a part of the on-chip lens in the vicinity of the on-chip lens. It is preferable.

  According to this configuration, each of the pixel sets can diminish the luminous flux within a predetermined incident angle range by the lens action of the on-chip lens and the dimming means that covers a part of the image sensor on-chip. The amount of light can be secured even by covering the wide range by the dimming means. This has an effect that it is easy to cope with a change in the aperture of the photographing lens while securing the light amount. In this method, the number of pixel sets can be easily increased.

  The dimming means is preferably an ND filter.

  In the imaging apparatus according to the present invention, the pixel set includes a pixel set R in which the right half of the on-chip lens is covered by a dimming unit, and a pixel set L in which the left half is covered. The output signal from the pixel set is preferably an output signal in the horizontal direction of the pixel set L and the pixel set R.

  According to this configuration, the dimming means covers the right and left halves so that it can easily cope with changes in the aperture of the photographic lens, ensuring a well-balanced amount of light required for image formation and phase difference AF accuracy. it can.

  In the imaging apparatus according to the present invention, as the pixel set, the pixel set R in which the right half of the on-chip lens is covered by the dimming unit, the pixel set L in which the left half is covered, and the on-chip lens by the dimming unit The pixel set U in which the upper half is covered and the pixel set S in which the lower half is covered, and output signals from the two types of pixel sets are output in the horizontal direction of the pixel set L and the pixel set R. A signal or an output signal in the vertical direction of the pixel set U and the pixel set S is preferable.

  According to this configuration, the dimming means covers the right half, left half, upper half, and lower half of each pixel set so that it can easily respond to changes in the aperture of the taking lens, and the amount of light necessary for image formation. In addition, the accuracy of the phase difference AF can be secured in a balanced manner, and the number of subjects that can be AF can be increased.

In the imaging device according to the present invention, it is preferable that a color filter is disposed in front of the photoelectric conversion surface of the pixel.
In this configuration, since color information is not lost due to the dimming action, a color image can be obtained.

In the imaging device according to the present invention, it is preferable that the pixels on which color filters are arranged form the pixel set.
Thereby, good AF is possible regardless of the color of the subject.

In the imaging apparatus according to the present invention, it is preferable that the dimming unit satisfies the following conditional expression (3).
50% ≦ T ≦ 85% (3)
Where T is the transmittance.

According to this configuration, when the transmissivity T is 50%, if a dimming action is applied to half of the incident light flux, a total amount of light of 75% can be secured, and the influence on image formation is reduced.
If the lower limit of conditional expression (3) is not reached, shooting of a subject with low illuminance will be affected. If the upper limit of conditional expression (3) is exceeded, acquisition of phase difference information becomes difficult and AF accuracy deteriorates.

(First embodiment)
The first embodiment is a reference example. FIG. 1 is a diagram illustrating a basic configuration of the imaging apparatus according to the first embodiment.
As shown in FIG. 1, the imaging apparatus according to the first embodiment includes a photographing lens 102 and an imaging element 103 having a defocus detection pixel disposed on the optical axis 101 of the photographing lens 102. The photographing lens 102 is provided with an aperture stop 104 and a light reduction unit 105 on the optical axis 101. As shown in FIG. 1, the dimming means 105 is preferably arranged in the vicinity of the aperture stop 104 in the photographic lens 102, but is not limited to this. It may be arranged at a position corresponding to the assumed exit pupil position).

FIG. 2 is a plan view showing the configuration of the dimming unit 105 according to the first embodiment, and is a view of the dimming unit 105 viewed from the direction of the optical axis 101.
As shown in FIG. 2, the dimming unit 105 is provided with a first polarizing region 106 </ b> L on the left side and a second polarizing region 106 </ b> R on the right side with the optical axis 101 as the center. These polarizing regions are arranged at positions where a light beam having a predetermined incident angle range that enters a pixel set described below passes, and the first polarizing region 106L and the second polarizing region 106R are 90 degrees from each other. Dimming or shielding light beams with different polarization directions. In addition, a transmission region 106T is disposed in a range excluding the first polarization region 106L and the second polarization region 106R in the light beam passage range of the photographing lens 102.

FIG. 3 is a plan view illustrating an arrangement example of pixels of the image sensor 103 according to the first embodiment, and is a diagram of the image sensor 103 viewed from the direction of the optical axis 101.
The image sensor 103 has a plurality of pixels 120 arranged two-dimensionally. In addition, in a plane orthogonal to the optical axis 101, a group of pixels that receive a light beam having a predetermined incident angle range among the plurality of pixels 120 form a first pixel set 103a and a second pixel set 103b, respectively. ing. These pixel sets are arranged along a first direction A1 and a second direction B1 that are orthogonal to each other. In the arrangement example of the image sensor 103 shown in FIG. 3, the first pixel set 103a and the second pixel set 103b are arranged in a checkered pattern. In the first pixel set 103a, a polarizer that reduces the amount of light in the polarization direction that has been attenuated by the first polarization region 106L is disposed. In the second pixel set 103b, a polarizer that reduces the amount of light in the polarization direction that has been attenuated by the second polarization region 106R is disposed. The defocus information is acquired by comparing the signal from the first pixel set 103a and the output signal from the second pixel set 103b in at least one of the first direction A1 and the second direction B1.

FIG. 4 is a cross-sectional view showing the structure of the pixel 120 in the first embodiment.
As shown in FIG. 4, an on-chip lens 108 </ b> L and a polarizer 109 </ b> L are arranged in order from the object side so as to correspond to the photoelectric conversion surface 123 </ b> L of the pixel 120. In addition, an on-chip lens 108R and a polarizer 109R are arranged in order from the object side so as to correspond to the photoelectric conversion surface 123R of the pixel 120. Between the photoelectric conversion surfaces 123L and 123R and the on-chip lenses 108L and 108R, light shielding members 124 that define the photoelectric conversion regions of the photoelectric conversion surfaces 123L and 123R are respectively provided. The optical axes 107L and 107R pass through the center of each pixel and the photoelectric conversion surfaces 123L and 123R.
A color filter may be arranged in the vicinity of the polarizers 109L and 109R. With this configuration, the focus detection signal and the image formation signal can be acquired from all the pixels. In addition, it is desirable to use a polarizing filter with a low degree of polarization as the polarizers 109L and 109R because it can receive a sufficient amount of light.

FIG. 5 is a plan view showing a configuration of the dimming means 155 according to the first modification of the first embodiment, and is a view of the dimming means 155 as seen from the direction of the optical axis 101.
The dimming means is not limited to the dimming means 105 having the configuration shown in FIG. 2, and may be configured like the dimming means 155 shown in FIG. In this dimming means 155, no transmission region is provided, and the first polarization region 161L and the second polarization region 161R are arranged symmetrically around the optical axis 101. The polarization degree of the polarizing filter forming the first polarizing region 161L and the second polarizing region 161R may be reduced. Preferably, the light transmittance of the first polarization region 161L and the second light region 161R is 50% or more.

  The polarizer disposed in the first pixel set 103a reduces more of the light beam in the polarization direction dimmed in the first polarization region 161L, and the polarizer disposed in the second pixel set 103b is the second polarized light. The light beam in the polarization direction dimmed in the region 161R is further dimmed.

When the dimming means 105 shown in FIG. 2 or the dimming means 155 as shown in FIG. 5 is used, in FIG. 3, for example, L04F02, L03F03, L04F04, L03F05, L04F06, L03F07, L04F08, L03F09 of the pixel set 103b are obtained in this order. Signal waveform obtained in the order of L03F02, L04F03, L03F04, L04F05, L03F06, L04F07, L03F08, L04F09 in the pixel set 103a in the order of the left image and calculating the phase difference between the left and right images. The defocus amount of the taking lens is obtained based on the value. FIG. 3 shows 16 pixels in the vertical direction and 16 pixels in the horizontal direction, but when the total number of pixels exceeds 1,000,000, the arrangements such as L0402, L03F03, L04F04, L03F05, L04F06, L03F07, L04F08, and L03F09 are substantially It can be treated like a horizontal line.
Here, when a specific pixel is shown, row numbers L01-16 and column numbers F01-16 are shown side by side. For example, the pixel corresponding to the column F01 in the L01 row is represented by “L01F01”.

FIG. 6 is a plan view showing the configuration of the dimming means 205 according to the second modification of the first embodiment, and is a view of the dimming means 205 as seen from the direction of the optical axis 101.
The dimming means is not limited to the dimming means 105 in FIG. 2 and the dimming means 155 in FIG. 5, but may be configured as the dimming means 205 shown in FIG. 6. The dimming unit 205 includes four regions provided at equiangular intervals with respect to the optical axis 101. Among these regions, the first polarization region 212L and the second polarization region 212R are respectively disposed in two regions that are symmetric with respect to the optical axis 101, and the transmission region 212T is disposed in each of the remaining two regions.

  The polarizer arranged in the first pixel set 103a reduces more of the light beam in the polarization direction dimmed in the first polarization region 212L, and the polarizer arranged in the second pixel set 103b is the second polarized light. More light in the polarization direction attenuated in the region 212R is attenuated more.

  FIG. 7 is a plan view showing the position of the area centroid 213LC of the light amount of the light beam incident on the first pixel set 103a in the dimming means 205 according to the second modification of the first embodiment. FIG. 8 is a plan view showing the area centroids 213LC and 213RC and the area centroid equivalent position in the dimming means 205 according to the second modification of the first embodiment. 7 and 8 are views of the dimming unit 205 viewed from the direction of the optical axis 101. FIG.

The light beam incident on the first pixel set 103a passes through the aperture stop 104 and the dimming means 205, and the area centroid 213LC of the light amount exists in a region symmetrical to the first polarization region 212L with respect to the optical axis 101 (FIG. 7). ). Similarly, the area centroid 213RC of the light amount of the light beam incident on the second pixel set 103b exists in a region symmetrical to the second polarization region 212R with respect to the optical axis 101 (FIG. 8).
By configuring in this way, when the signals from the first pixel set and the second pixel set are compared in the vertical direction, phase difference information obtained by dividing the pupil in the vertical direction is obtained, and when compared in the horizontal direction, Phase difference information obtained by dividing the pupil into left and right can be obtained.

  For example, the signal waveforms obtained in the order of L04F02, L03F03, L04F04, L03F05, L04F06, L03F07, L04F08, and L03F09 in the second pixel set 103b are the right images, and L03F02, L04F03, L03F04, L04F05, and L03F06 in the first pixel set 103a are used. A signal waveform obtained in the order of L04F07, L03F08, and L04F09 is set as the left image, and the phase difference between the left and right images is calculated therefrom. At this time, in order to obtain the defocus amount of the photographing lens 102, the phase difference between the left and right images is detected from the area centroid equivalent position 214RH and the area centroid equivalent position 214LH, and the defocus amount is calculated from the value. Here, as shown in FIG. 8, the area gravity center equivalent position 214RH is a position projected from the area gravity center 213RC to the horizontal line 205H passing through the optical axis 101, and the area gravity center equivalent position 214LH is projected from the area gravity center 213LC to the horizontal line 205H. Is the position.

  Regarding the phase difference between the upper and lower images, the signal waveforms obtained in the order of L04F02, L05F03, L06F02, L07F03, L08F02, L09F03, L10F02, and L11F03 in the second pixel set 103b are set as upper images, and L04F03 in the first pixel set 103a. A signal waveform obtained in the order of L05F02, L06F03, L07F02, L08F03, L09F02, L10F03, and L11F02 is set as the lower image, and the phase difference between the upper and lower images is calculated therefrom. At this time, in order to obtain the defocus amount of the photographing lens 102, the phase difference between the upper and lower images is detected from the area centroid equivalent position 214RV and the area centroid equivalent position 214LV, and the defocus amount is calculated from the value. Here, as shown in FIG. 8, the area centroid equivalent position 214RV is a position projected from the area centroid 213RC onto the vertical line 205V passing through the optical axis 101, and the area centroid equivalent position 214LV is perpendicular to the area centroid 213LC from the vertical line 205V. This is the projected position.

Further, instead of the image sensor 103 in FIG. 3, the image sensor 253 illustrated in FIG. 9 and the color filter 260 illustrated in FIG.
FIG. 9 is a plan view conceptually showing the pixel arrangement in the image sensor 253 according to the third modification of the first embodiment. FIG. 10 is a plan view conceptually showing the arrangement of the color filters 260 corresponding to FIG.
The imaging element 253 includes a plurality of pixels 250 that are two-dimensionally arranged in a first direction A1 and a second direction B1 that are orthogonal to each other in a plane orthogonal to the optical axis 101. The pixel arrangement example shown in FIG. 9 is a combination of the first pixel set 253a and the second pixel set 253b, and the same type of pixel is arranged for every two adjacent rows and two columns of pixels. For example, the pixels in adjacent two rows and two columns of L01F01, L01F02, L02F01, and L02F02 all constitute the first pixel set 253a, and any of the adjacent pixels in two rows and two columns of L01F03, L01F04, L02F03, and L02F04 Constitutes the second pixel set 253b.

The arrangement of the color filters in FIG. 10 is such that the L01F01 pixel is a green filter G, the L01F02 pixel is a red filter R, L02F01 is a blue filter B, and L02F02 is a green filter G. Is repeated. This combination pattern is arranged corresponding to adjacent two rows and two columns of pixels in which pixels of the same type are arranged in FIG.
By associating the pixel arrangement of FIG. 9 with the arrangement of the color filters of FIG. 10, a color image can be acquired and high-precision focus detection can be performed regardless of the color of the subject.

(Second Embodiment)
FIG. 11 is a diagram illustrating a basic configuration of an imaging apparatus according to the second embodiment.
As illustrated in FIG. 11, the imaging apparatus according to the second embodiment includes a photographic lens 302 and an imaging element 320 having a defocus detection pixel disposed on the optical axis 301 of the photographic lens 302. Further, a dimming unit 310 is disposed on the optical axis 301 on the imaging lens 302 side of the image sensor 320. The position where the dimming means 310 is disposed is preferably a predetermined position from the image sensor 320 (a position corresponding to the exit pupil position assumed in the system).

FIG. 12 is a plan view of the image pickup device 320 and the dimming unit 310 according to the second embodiment as viewed from the direction of the optical axis 301.
The imaging element 320 has a plurality of pixels that are two-dimensionally arranged with respect to the first direction A1 and the second direction B1 orthogonal to each other in a plane orthogonal to the optical axis 301. The dimming unit 310 includes a transmissive region 320T and a dimming region 320D, and is arranged to divide each pixel of the image sensor 320 into two equal parts in the first direction A1.

  The dimming region 320D preferably has the same configuration as a so-called ND filter, and is particularly preferably a light absorption type because flare due to reflection does not occur. Further, the transmittance of the dimming region 320D is preferably 50% or more and 85% or less with respect to the transmission region 320T.

  In the example illustrated in FIG. 12, the pixels of the image sensor 320 are covered with the pixel set R (F01, F03, F05, F07, F09, F11, F13, and F15) in which the right half is covered by the dimming region 320D. It is divided into a pixel set L (F02, F04, F06, F08, F10, F12, F14, F16) in which half is covered. Of the pixels of the image sensor 320, the left half of the pixel set R and the right half of the pixel set L correspond to the transmissive region 320T.

  Each dimming region 320D covers the right half of one of the two adjacent pixels and covers the left half of the other. For example, the right side of the F03 column and the left side of the F04 column are covered with one dimming region 320D.

Thereby, the rows F01, F03, F05, F07, F09, F11, F13, and F15 in FIG. 12 further reduce the light flux coming from the right side of the pixel, and F02, F04, F06, F08, F10, F12, F14, The row F16 further diminishes the light beam coming from the left side of the pixel. In addition, since one dimming region 320D covers each half of two adjacent pixels, efficiency degradation due to crosstalk can be prevented. For example, when focusing on the upper right area of the screen, the signal waveforms obtained in the order of L03F02, L03F04, L03F06, and L03F08 are the left image, and the signal waveforms obtained in the order of L03F03, L03F05, L03F07, and L03F09 are the right image. Alternatively, the phase difference information of the left and right images may be calculated, and the defocus amount of the photographic lens may be obtained based on this value.
FIG. 12 shows 16 pixels in the vertical direction and 16 pixels in the horizontal direction. However, if the imaging element exceeds 1,000,000 pixels, the number of pixels for detecting the phase difference information can be increased to increase the accuracy.

FIG. 13 is a plan view of the imaging device 370 and the light reduction unit 360 according to the first modification of the second embodiment viewed from the direction of the optical axis 301.
Similar to the above-described imaging element 320, the imaging element 370 includes a plurality of pixels that are two-dimensionally arranged in the first direction A1 and the second direction B1 that are orthogonal to each other in a plane orthogonal to the optical axis 301. Have. The light reduction means 360 includes a transmission region 370T and a light reduction region 370D, and is arranged so as to divide each pixel of the image sensor 370 into two equal parts in the first direction A1 or the second direction B1. The dimming region 370D preferably has the same configuration as a so-called ND filter. In particular, the light absorption type is preferably a light absorption type because no flare due to reflection occurs. Further, the transmittance of the dimming region 370D is preferably 50% or more and 85% or less with respect to the transmission region 320T.

  In the example illustrated in FIG. 13, the pixels of the image sensor 370 have a pixel set R in which the right half is covered (for example, L01F01 and L02F01) and a pixel set L in which the left half is covered by the dimming region 370D (for example, L01F02, L02F02), a pixel set U (for example, L02F03, L02F04) whose upper half is covered, and a pixel set S (for example, L01F03, L01F04) whose lower half is covered. Of the pixels of the image sensor 370, a region not covered with the light reduction region 370D corresponds to the transmission region 370T.

The dimming region 370D has two adjacent pixels: (1) one pixel covers the right half and the other pixel covers the left half, and (2) one pixel covers the upper half, The other pixel may cover the lower half. For example, in the case of (1), the right side of the L01F01 pixel and the left side of the L01F02 pixel are covered with one dimming region 370D. In the case of (2), the lower side of the L01F03 pixel and the upper side of the L02F03 pixel are covered with one dimming region 370D. With this configuration, the influence of crosstalk can be reduced.
By comparing the signal information in the horizontal direction of the pixel set R and the pixel set L with each other, phase difference information can be acquired in the horizontal direction (first direction A1, horizontal direction). By comparing the signal information with each other, phase difference information in the vertical direction (second direction B1, vertical direction) can be acquired.

Here, an example of a pixel structure in the imaging apparatus according to the second embodiment will be described. FIG. 14 is a cross-sectional view showing the structure of the pixel 420 in the second embodiment.
As shown in FIG. 14, a dimming means 405 and an on-chip lens 408L are arranged in order from the object side so as to correspond to the photoelectric conversion surface 423L of the pixel 420. Further, a dimming means 405 and an on-chip lens 408R are arranged in order from the object side so as to correspond to the photoelectric conversion surface 423R of the pixel 420. Between the photoelectric conversion surfaces 423L and 423R and the on-chip lenses 408L and 408R, light shielding members 424 that define photoelectric conversion regions of the respective photoelectric conversion surfaces 423L and 423R are provided. The optical axes 407L and 407R pass through the center of each pixel and the photoelectric conversion surfaces 423L and 423R.

  The dimming means 405 has a transmissive area 405T and a dimming area 405D. As shown in FIG. 14, the dimming area 405D is arranged so as to correspond to the area from the optical axis 407L of the on-chip lens 408L to the optical axis 407R of the on-chip lens 408R, and the transmission area 405T is the dimming area 405D. Arranged outside.

FIG. 15 is a cross-sectional view illustrating a structure of a pixel 470 according to a second modification of the second embodiment.
In the pixel 420 illustrated in FIG. 14, the dimming unit 405 is disposed on the object side in the vicinity of the on-chip lenses 408L and 408R. However, as illustrated in FIG. 15, the dimming unit 455 is disposed on the on-chip lenses 458L and 458R. It can also be arranged on the photoelectric conversion surfaces 473L and 473R side in the vicinity.

  Between the photoelectric conversion surfaces 473L and 473R and the on-chip lenses 458L and 458R, a light shielding member 474 that defines a photoelectric conversion region of each of the photoelectric conversion surfaces 473L and 473R is provided. The optical axes 457L and 457R pass through the center of each pixel and the photoelectric conversion surfaces 473L and 473R.

  The light reduction means 455 has a transmission region 455T and a light reduction region 455D. As shown in FIG. 15, the dimming area 455D is arranged so as to correspond to the area from the optical axis 457L of the on-chip lens 458L to the optical axis 457R of the on-chip lens 458R, and the transmission area 455T is the dimming area 455D. It is arranged outside.

  Note that the amount of light received by the image sensor can be set by the amount of light reduction in the light reduction region.

  FIG. 16 is a plan view of the pixels of the image sensor according to the first comparative example and the dimming unit viewed from the direction of the optical axis. FIG. 17 is a plan view of the pixels of the image sensor according to the second comparative example and the dimming unit viewed from the direction of the optical axis. FIG. 18 is a plan view of the pixels of the image sensor according to the third comparative example and the dimming unit viewed from the direction of the optical axis.

  As described above, in the imaging device according to the second embodiment and the modification thereof, the configuration is such that the pixels are covered by the dimming region and the transmission region in half. On the other hand, as shown in FIGS. 16 to 19, a configuration in which the dimming region is not half of the pixel is also conceivable. Although phase difference information can be acquired with this configuration as well, as shown in FIG. 16, if the dimming area 501 is made wider than the transmission area 502, the amount of light received by the pixels is reduced, leading to a reduction in image quality. In addition, as shown in FIG. 17, if the light shielding area 511 is made narrower than the transmission area 512 and the central portion of the pixel is left, the defocus detection accuracy is deteriorated. Furthermore, as shown in FIG. 18, if the light shielding region 521 is made narrower than the transmission region 522 and the peripheral portion of the pixel is left, defocus detection becomes difficult when the F-number of the photographing lens is increased. Therefore, it is preferable that the pixel is covered half by the light reduction region and the transmission region.

The imaging device according to the second embodiment and its modification can be configured to acquire a color image. FIG. 19 is a diagram showing the arrangement of the pixels of the image sensor and the light reducing means 550 in the second embodiment, and is a plan view seen from the direction of the optical axis.
The light reduction means 550 includes a transmission region 550T and a light reduction region 550D, and is arranged so as to divide each pixel of the image sensor into two equal parts in the first direction A1 or the second direction B1. The dimming region 550D preferably has a configuration similar to that of a so-called ND filter. In particular, a light absorption type is preferable because flare due to reflection does not occur. Further, the transmittance of the light reduction region 550D is preferably 50% or more and 85% or less with respect to the transmission region 320T.

  In the example illustrated in FIG. 19, the pixels of the imaging element are pixel sets R (for example, L01F01 and L02F01) whose right half is covered and pixel sets L (for example, L03F03) whose left half is covered by the dimming region 550D. , L04F03), a pixel set U in which the upper half is covered (for example, L01F03, L02F03), and a pixel set S in which the lower half is covered (for example, L03F01, L04F01). Of the pixels of the image sensor, the region not covered with the light reduction region 550D corresponds to the transmission region 550T. The dimming region 550D is arranged so that the pixels of the image sensor belong to the same pixel set every two rows and two columns from L01F01.

When the color filter shown in FIG. 10 is configured to overlap the image sensor having the above configuration, a color image can be acquired.
FIG. 20 is a cross-sectional view illustrating a structure example of a pixel 620 according to a third modification of the second embodiment.
As shown in FIG. 20, a dimming unit 610, an on-chip lens 608L, and a color filter 630 are arranged in order from the object side so as to correspond to the photoelectric conversion surface 623L of the pixel 620. Further, a dimming unit 610, an on-chip lens 608R, and a color filter 630 are arranged in order from the object side so as to correspond to the photoelectric conversion surface 623R of the pixel 620. Between the photoelectric conversion surfaces 623L and 623R and the on-chip lenses 608L and 608R, a light shielding member 624 that defines a photoelectric conversion region of each of the photoelectric conversion surfaces 623L and 623R is provided. The optical axes 607L and 607R pass through the center of each pixel and the photoelectric conversion surfaces 623L and 623R.

  The light reduction means 610 has a transmission region 610T and a light reduction region 610D. In the example shown in FIG. 20, the transmission region 610T and the light reduction region 610D are arranged on both sides with the optical axis 607L of the on-chip lens 608L as a boundary in the region corresponding to the photoelectric conversion surface 623L, and the photoelectric conversion surface 623R In the corresponding region, the on-chip lens 608R is disposed on both sides with the optical axis 607R as a boundary.

FIG. 21 is a cross-sectional view illustrating a structural example of a pixel 620 according to a fourth modification of the second embodiment.
As illustrated in FIG. 21, an on-chip lens 658 </ b> L, a light reduction unit 660, and a color filter 680 are arranged in order from the object side so as to correspond to the photoelectric conversion surface 673 </ b> L of the pixel 670. In addition, an on-chip lens 658R, a light reduction unit 660, and a color filter 680 are arranged in order from the object side so as to correspond to the photoelectric conversion surface 673R of the pixel 670. Between the photoelectric conversion surfaces 673L and 673R and the on-chip lenses 658L and 658R, light shielding members 674 for defining photoelectric conversion regions of the photoelectric conversion surfaces 673L and 673R are respectively provided. The optical axes 657L and 657R pass through the center of each pixel and the photoelectric conversion surfaces 673L and 673R.

  The light reduction means 660 has a transmission region 660T and a light reduction region 660D. In the example shown in FIG. 21, the transmissive region 660T and the dimming region 660D are respectively arranged on both sides with the optical axis 657L of the on-chip lens 658L as a boundary in the region corresponding to the photoelectric conversion surface 673L. In the corresponding region, the on-chip lens 658R is disposed on both sides with the optical axis 657R as a boundary.

As described above, in the fourth modification, the dimming unit 660 and the color filter 680 are disposed on the photoelectric conversion surfaces 673L and 673R side in the vicinity of the on-chip lenses 658L and 658R of the pixel. With this configuration, the influence of crosstalk can be reduced. The order of the dimming means 660 and the color filter 680 may be reversed. With this configuration, a color image can be acquired.
In addition, about another structure, an effect | action, an effect, and a modification of 2nd Embodiment, it is the same as that of 1st Embodiment.

  Here, an outline of the configuration and processing of the camera system to which the imaging device according to the first embodiment, the second embodiment, or the modifications thereof is applied will be described. FIG. 22 is a block diagram showing in more detail the configuration of an interchangeable lens camera system (imaging system).

First, in the interchangeable lens camera system shown in FIG. 22, when the interchangeable lens 800 is mounted on the body mount / lens mount coupling portion 701 of the camera body (camera body) 700, the lens is mounted on the camera body 700 side. Detected.
Next, distortion information, feed amount information, and the like stored in the lens information recording unit 806 in the interchangeable lens 800 are transferred to and recorded in the lens information storage unit 703 in the camera body 700. At this time, if there is no distortion data in the lens information recording unit 806, the distortion amount may be set to 0 and recorded in the lens information storage unit 703.

  When the user performs an operation such as half-pressing a release button (shutter button) 702, a ranging start instruction signal is output to the camera controller 710. At this time, a process of setting a distance measurement part may be entered. The setting of the distance measurement part may be set manually by the user, or may be set according to a rule set in advance by the camera.

When ranging is started, each pixel of the image sensor 721 performs photoelectric conversion. At this time, pixels that are selectively subjected to photoelectric conversion may be set as necessary.
The photoelectrically converted signal is converted into a digital signal by an ADC (analog / digital conversion circuit) 722 and output to the preprocessing unit 717. This signal is converted into a format suitable for processing by the image processing units 715 and 711 in the preprocessing unit 717. The image sensor 721 operates in accordance with an output from a TG (timing generator) controlled by the camera controller 710.

  When the distance measurement is started, the focus lens position information stored in the zoom state calculation unit 812 of the interchangeable lens 800 is transferred and recorded to the lens state recording unit 704 in the camera body 700. Here, when the interchangeable lens 800 is a zoom lens, information on the state of the focal length may be transferred in addition to the focus lens position information. The focus lens position information is information calculated by the zoom state calculation unit 812 by a predetermined method based on the position information of the photographing lens system 802 including the focus lens 801 detected by the zoom lens group position detection unit 804.

  Through the above-described photoelectric conversion, the image processing unit 711 acquires photoelectric conversion information of the first pixel set A of the distance measurement portion, and forms an A image.

  Further, the image processing unit 711 (correction unit) converts the formed A image into an A1 image by correcting the distortion using the distortion information transferred to the lens information storage unit 703 in the body.

In addition, through the photoelectric conversion described above, the image processing unit 711 acquires photoelectric conversion information of the second pixel set B of the distance measurement portion, and forms a B image.
Here, the first pixel set A constitutes one photoelectric conversion cell group, and the second pixel set B constitutes another photoelectric conversion cell group.

Further, the image processing unit 711 converts the formed B image into a B1 image by correcting the distortion using the distortion information transferred to the lens information storage unit 703.
The phase difference calculation unit 713 compares the A1 image and the B1 image, and calculates the phase difference amount S1 for calculating the defocus amount.

  The lens drive amount calculation unit 714 determines that the in-focus state is obtained when the calculated phase difference amount S1 is within the predetermined amount, and determines that the in-focus state is exceeded when the predetermined amount is exceeded. Here, the predetermined amount may be set from the depth of field calculated from the minimum circle of confusion, or information from the photographing lens may be referred to.

  When it is determined that the phase difference amount S1 exceeds the predetermined amount, the phase difference amount S1, the feed amount information recorded in the lens information storage unit 703, the information such as the focus lens position recorded in the lens state recording unit 704, and the like The lens drive amount calculation unit 714 calculates the lens extension amount D1. The calculation method of the feeding amount D1 can use the same method as the conventional phase difference AF. The feeding amount D1 may be a feeding direction amount or a control value such as a driving pulse of a focus lens driving unit 803 (motor) that drives the focus lens 801.

  The camera controller 710 transfers the information of the calculated feed amount D1 to the lens controller 810 of the interchangeable lens 800. Based on the transferred feed amount D1, the focus lens control unit 811 causes the focus lens drive unit 803 to drive the focus lens 801 by the feed amount D1. At this time, the focus lens control unit 811 controls the focus lens drive unit 803 based on the position information of the focus lens 801 detected by the focus lens position detection unit 805. Note that communication between the camera controller 710 and the lens controller 810 is controlled by a communication control unit 718 in the camera controller 710.

  After driving the focus lens 801, the process returns to the step after the start of distance measurement, and the camera controller 710 confirms whether or not the in-focus state is achieved.

  On the other hand, when the lens drive amount calculation unit 714 determines that the phase difference amount S1 is within a predetermined amount, photoelectric conversion is performed in each pixel of the image sensor 721. The image processing unit 715 forms an image based on the photoelectrically converted signal. That is, the image processing unit 715 generates a captured image. The formed image is compressed in a predetermined format by the compression unit 716 and recorded in the image recording unit 731 (image recording unit). The compressed image is displayed on the image display unit 732.

In image formation in the image processing unit 715, in addition to image formation, image processing suitable for the entire image may be performed using information recorded in the lens information storage unit 703.
The image recording unit 731 may be a memory provided in the camera body 700 or an external memory attached to the camera body 700.

  As described above, the image pickup apparatus according to the present invention is useful when it is required to realize an image pickup apparatus having high ranging performance and little image quality deterioration with a simple configuration.

DESCRIPTION OF SYMBOLS 101 Optical axis 102 Shooting lens 103 Image pick-up element 103a 1st pixel set 103b 2nd pixel set 104 Aperture stop 105 Dimming means 106L 1st polarization area 106R 2nd polarization area 106T Transmission area 107L, 107R Optical axis 108L, 108R On-chip lens 109L, 109R Polarizer 120 Pixels 123L, 123R Photoelectric conversion surface 124 Light blocking member 155 Light attenuation means 161L First polarization area 161R Second polarization area 205 Light attenuation means 205H Horizontal line 205V Vertical line 212L First polarization area 212R Second polarization area 212T Transmission region 213LC, 213RC Area center of gravity 214LH, 214LV, 214RH, 214RV Area center of gravity equivalent position 250 pixels 253 Image sensor 253a First pixel group 253b Second pixel group 260 Color filter 301 Optical axis 302 Imaging lens 310 Dimming means 320 Imaging element 320D Dimming area 320T Transmission area 360 Dimming means 370 Imaging element 370D Dimming area 370T Transmission area 405 Dimming means 405D Dimming area 405T Transmission area 407L, 407R Optical axis 408L, 408R On-chip lens 420 Pixel 423L, 423R Photoelectric conversion surface 424 Light blocking member 455 Light reduction means 455D Light reduction region 455T Transmission region 457L, 457R Optical axis 458L, 458R On-chip lens 470 Pixel 473L, 473R Photoelectric conversion surface 474 501, 511, 521 Dimming area 502, 512, 522 Transmission area 550 Dimming means 550 D Dimming area 550 T Transmission area 607 L, 607 R Optical axis 608 L, 608 R On-chip lens 610 Dimming means 610D Dimming area 610T Transmission area 620 Pixel 623L, 623R Photoelectric conversion surface 624 Light blocking member 630 Color filter 657L, 657R Optical axis 658L, 658R On-chip lens 660 Dimming means 660D Dimming area 660T Transmission area 670 Pixel 67 673R photoelectric conversion surface 674 light shielding member 680 color filter 700 camera body 703 lens information storage unit 704 lens state recording unit 710 camera controller 711, 715 image processing unit 713 phase difference amount calculating unit 714 lens driving amount calculating unit 721 imaging element 731 image recording 732 Image display unit 800 Interchangeable lens 801 Focus lens 802 Shooting lens system 803 Focus lens drive unit 804 Zoom lens group position detection unit 805 Focus lens position Detector 806 lens information recording section 810 the lens controller 811 a focus lens control unit 812 zoom state calculating section

Claims (4)

An imaging device in which a photographic lens can be attached or a photographic lens is fixed,
An imaging device having a plurality of pixels arranged two-dimensionally and an on-chip lens arranged in front of the photoelectric conversion surface corresponding to the plurality of pixels ;
The plurality of pixels each include at least two types of pixel sets formed by one or more pixels that receive a light flux having a predetermined incident angle range,
A dimming means disposed in front of the photoelectric conversion surface of each of the pixel sets so as to dimm the luminous flux having the predetermined incident angle range;
A phase difference amount calculation unit that calculates a phase difference amount by comparing output signals from at least two types of pixel sets;
An image processing unit for forming an image from pixel information;
Have
The dimming means is a light absorption type ND filter that is disposed in the vicinity of the on-chip lens, is discretely disposed so as to cover a part of the on-chip lens, and does not substantially lose color information. There, an imaging apparatus characterized by satisfying the following conditional expression (3).
50% ≦ T ≦ 85% (3)
Where T is the transmittance.   The imaging apparatus according to claim 1, wherein any of the pixel sets includes an image forming pixel. The pixel set includes a pixel set R in which the right half of the on-chip lens is covered by the dimming means, and a pixel set L in which the left half is covered,
  3. The imaging apparatus according to claim 1, wherein output signals from the two types of pixel sets are output signals in the horizontal direction of the pixel set L and the pixel set R. 4. As the pixel set, a pixel set R in which the right half of the on-chip lens is covered by the dimming means, a pixel set L in which the left half is covered, and an upper half of the on-chip lens are covered by the dimming means. A pixel set U and a pixel set S in which the lower half is covered,
  The output signals from the two types of pixel sets are output signals in the horizontal direction of the pixel set L and the pixel set R, or output signals in the vertical direction of the pixel set U and the pixel set S. The imaging apparatus according to claim 1 or 2.

Images