JP2013140385A - Focus detecting device and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus detecting device capable of preventing deterioration of focus detection accuracy due to crosstalk.SOLUTION: A focus detecting device comprises: a pixel array for focus detection in which a plurality of pixels for focus detection comprising photoelectric conversion parts are arrayed to produce a pair of image signals corresponding to a pair of images formed by a pair of beams passing through an optical system; correction means (S130) for correcting output signals of the photoelectric conversion parts in accordance with output signals of photoelectric conversion parts around the photoelectric conversion parts; image deviation detection means (S140) for detecting a relative deviation amount between the pair of images, on the basis of the pair of image signals produced by the output signals of the photoelectric conversion parts after correction with the correction means (S130); and focus detection means (S140) for detecting a focus adjusting state of the optical system on the basis of the deviation amount between the pair of images detected by the image deviation detection means (S140).

Description

  The present invention relates to a focus detection apparatus and an imaging apparatus.

  A focus detection apparatus using a pupil division type phase difference detection method is known (see, for example, Patent Document 1). In this focus detection apparatus, a plurality of focus detection pixels each provided with a pair of photoelectric conversion units are arranged for one microlens to detect a pair of images.

Japanese Patent Laid-Open No. 55-130524

  However, in the conventional focus detection apparatus described above, when a pair of images is detected by the pair of photoelectric conversion units of the focus detection pixels, output leakage (crosstalk) occurs between the photoelectric conversion units. As a result, it was found that the detection accuracy of the image shift amount deteriorated.

In the focus detection apparatus according to the first aspect of the present invention, a plurality of focus detection pixels having first and second photoelectric conversion units are arranged in the radial direction from the center of the shooting screen around the shooting screen, and pass through the optical system. A focus detection pixel array that receives a pair of images formed by the pair of luminous fluxes received by the first and second photoelectric conversion units and generates a pair of image signals, and the first photoelectric conversion unit. And the output signal of the second photoelectric conversion unit with a crosstalk correction amount based on the first crosstalk rate resulting from the distance from the center of the shooting screen to the position of the second photoelectric conversion unit. And a crosstalk correction amount based on an output signal of the second photoelectric conversion unit and a second crosstalk rate resulting from the distance from the center of the shooting screen to the position of the first photoelectric conversion unit. The output of the first photoelectric converter Based on the correction signal for correcting the signal and the pair of image signals generated by the output signals of the first and second photoelectric conversion units corrected by the correction unit, the deviation amount of the pair of images And a focus detection unit for detecting a focus adjustment state of the optical system based on an amount of shift of the image detected by the image shift detection unit. The distance between the conversion unit and the center of the shooting screen is greater than the distance between the second photoelectric conversion unit and the center of the shooting screen, and the second crosstalk rate is greater than the first crosstalk rate. Is also large.
A focus detection device according to a sixth aspect of the present invention is a two-dimensional array of imaging pixels each having a photoelectric conversion unit that receives a light beam passing through an optical system and outputs an imaging output signal; A focus detection pixel having first and second photoelectric conversion units juxtaposed in a first direction so as to receive a pair of light beams passing through the optical system is disposed in the array of the imaging pixels. A focus detection pixel array that generates a pair of image signals corresponding to a pair of images formed by the pair of light beams, and a focus detection pixel of the focus detection pixel array. Crosstalk based on the output signals of the first photoelectric conversion units based on the output signals of the second photoelectric conversion units located on both sides of the first photoelectric conversion unit of the focus detection pixel with respect to the first direction. The amount of correction and multiple images in the vicinity of the focus detection pixel. While correcting with the crosstalk correction amount based on each output signal of the photoelectric conversion unit of the image pixel, the focus detection of the output signal of the second photoelectric conversion unit of the focus detection pixel with respect to the first direction is performed. Crosstalk correction amount based on each output signal of the first photoelectric conversion unit located on both sides of the second photoelectric conversion unit of the pixel for detection, and photoelectric conversion of a plurality of imaging pixels in the vicinity of the focus detection pixel Correction means for correcting with a crosstalk correction amount based on each of the output signals of the first and second image signals generated by the output signals of the first and second photoelectric conversion sections after correction by the correction means And an image shift detection unit for detecting a shift amount of the pair of images, and a focus adjustment state of the optical system based on the shift amount of the pair of images detected by the image shift detection unit. Focus detection means to detect Characterized in that it comprises a.
A focus detection device according to an eighth aspect of the present invention is a two-dimensional array of a plurality of imaging pixels each having a photoelectric conversion unit that receives a light beam passing through an optical system and outputs an imaging output signal; A focus detection pixel having first and second photoelectric conversion units juxtaposed in a first direction so as to receive a pair of light beams passing through the optical system is disposed in the array of the imaging pixels. A focus detection pixel array that generates a pair of image signals corresponding to a pair of images formed by the pair of light beams, and a focus detection pixel of the focus detection pixel array. While correcting the output signal of the first photoelectric conversion unit with the first crosstalk correction amount based on the output signal of the second photoelectric conversion unit adjacent in the same focus detection pixel as the first photoelectric conversion unit , The output signal of the second photoelectric conversion unit of the focus detection pixel Is corrected with a second crosstalk correction amount based on the output signal of the adjacent first photoelectric conversion unit within the same focus detection pixel as the second photoelectric conversion unit, and after correction by the correction unit An image shift detection unit that detects a shift amount of the pair of images based on the pair of image signals generated from output signals of the first and second photoelectric conversion units, and the image shift detection unit A focus detection unit that detects a focus adjustment state of the optical system based on a shift amount of the pair of images detected by the first detection unit, wherein the focus detection unit has a predetermined first crosstalk rate. And a storage means for storing the second crosstalk rate, wherein the correction means multiplies the first crosstalk rate by the output of the second photoelectric conversion unit. Calculate the first photoelectric conversion unit The output signal of the first photoelectric conversion unit is corrected by subtracting the first crosstalk amount from the force signal, and the first photoelectric conversion unit converts the second crosstalk amount to the second crosstalk rate. It is calculated by multiplying the output of the conversion unit, and the output signal of the second photoelectric conversion unit is corrected by subtracting the second crosstalk amount from the output signal of the second photoelectric conversion unit. To do.

  According to the present invention, it is possible to prevent a decrease in focus detection accuracy due to crosstalk.

Cross-sectional view showing a configuration of a camera according to an embodiment The figure which shows arrangement | positioning of the pixel for a focus detection on an imaging | photography screen Front view showing detailed configuration of image sensor Front view showing configuration of imaging pixel Front view showing configuration of focus detection pixel Diagram showing spectral sensitivity characteristics of imaging pixels The figure which shows the spectral sensitivity characteristic of the pixel for focus detection Sectional view showing structure of imaging pixel Sectional view showing structure of focus detection pixel The figure which shows the structure of the focus detection optical system of the pupil division type phase difference detection method using a micro lens The figure for demonstrating the cause which crosstalk generate | occur | produces in the pixel for focus detection The flowchart which shows the imaging operation of the digital still camera (imaging device) of one embodiment Explanatory diagram of crosstalk in focus detection pixels Diagram for explaining the evaluation method of correlation calculation results Front view showing an image sensor of a modified example Explanatory drawing of crosstalk of the image sensor shown in FIG. Explanatory drawing of crosstalk of the image sensor shown in FIG. Explanatory drawing of crosstalk when the pixels for focus detection provided with photoelectric conversion units having different sizes every other row are arranged Explanatory diagram of crosstalk when focus detection pixels are arranged in GB rows (v rows) of the Bayer array, and the upper and lower rows are RG imaging pixel arrays. Front view showing the configuration of an image sensor of another modification FIG. 20 is a front view showing a configuration of focus detection pixels arranged in the shape of an image sensor shown in FIG. Explanatory drawing of crosstalk of the image sensor shown in FIG. The figure for demonstrating that the influence of crosstalk changes according to the position of the pixel for focus detection on a screen.

  As an image pickup apparatus according to an embodiment, a lens interchangeable digital still camera will be described as an example. FIG. 1 is a cross-sectional view showing a configuration of a camera according to an embodiment. A digital still camera 201 according to an embodiment includes an interchangeable lens 202 and a camera body 203, and the interchangeable lens 202 is attached to the camera body 203 via a mount unit 204.

  The interchangeable lens 202 includes a lens 209, a zooming lens 208, a focusing lens 210, an aperture 211, a lens drive control device 206, and the like. The lens drive control device 206 includes a microcomputer (not shown), a memory, a drive control circuit, and the like. The lens drive control device 206 controls the driving of the focusing lens 210 and the aperture 211, detects the state of the zooming lens 208, the focusing lens 210 and the aperture 211, and the like In addition, the lens information is transmitted and the camera information is received by communication with a body drive control device 214 described later.

  The camera body 203 includes an imaging element 212, a body drive control device 214, a liquid crystal display element drive circuit 215, a liquid crystal display element 216, an eyepiece lens 217, a memory card 219, and the like. In the imaging element 212, imaging pixels are two-dimensionally arranged, and focus detection pixels are incorporated in portions corresponding to focus detection positions.

  The body drive control device 214 includes a microcomputer, a memory, a drive control circuit, and the like, and performs drive control of the image sensor 212 and reading of image signals and focus detection signals, image signal processing and recording, and focus detection calculation based on the focus detection signals. The focus adjustment of the interchangeable lens 202 and the operation control of the camera are performed. The body drive control device 214 communicates with the lens drive control device 206 via the electrical contact 213 to receive lens information and send camera information (defocus amount, aperture value, etc.).

  The liquid crystal display element 216 functions as a liquid crystal viewfinder (EVF: electrical viewfinder). The liquid crystal display element driving circuit 215 displays a through image by the imaging element 212 on the liquid crystal display element 216, and the photographer can observe the through image through the eyepiece lens 217. The memory card 219 is an image storage that stores an image captured by the image sensor 212.

A subject image is formed on the light receiving surface of the image sensor 212 by the light flux that has passed through the interchangeable lens 202. This subject image is photoelectrically converted by the image sensor 212, and an image signal and a focus detection signal are sent to the body drive control device 214.

  The body drive control device 214 calculates the defocus amount based on the focus detection signal from the focus detection pixel of the image sensor 212 and sends the defocus amount to the lens drive control device 206. In addition, the body drive control device 214 processes the image signal from the image sensor 212 and stores it in the memory card 219, and sends the through image signal from the image sensor 212 to the liquid crystal display element drive circuit 215, and transmits the through image to the liquid crystal. The image is displayed on the display element 216. Further, the body drive control device 214 sends aperture control information to the lens drive control device 206 to control the aperture of the aperture 211.

  The lens drive control device 206 changes the lens information according to the focusing state, zooming state, aperture setting state, aperture opening F value, and the like. Specifically, the positions of the zooming lens 208 and the focusing lens 210 and the aperture value of the aperture 211 are detected, and lens information is calculated according to these lens positions and aperture values, or a lookup prepared in advance. Lens information corresponding to the lens position and aperture value is selected from the table.

  The lens drive control device 206 calculates a lens drive amount based on the received defocus amount, and drives the focusing lens 210 to a focal point according to the lens drive amount. Further, the lens drive control device 206 drives the diaphragm 211 in accordance with the received diaphragm value.

  An interchangeable lens 202 having various imaging optical systems can be attached to the camera body 203 via a mount unit 204, and the camera body 203 is based on the output of focus detection pixels incorporated in the image sensor 212. The focus adjustment state 202 is detected.

  FIG. 2 is a diagram showing an arrangement of focus detection pixels on the shooting screen. When focus detection is performed based on an output of a focus detection pixel array described later, an area for sampling an image on the shooting screen (focus detection). Area, focus detection position). In this embodiment, an example is shown in which focus detection areas 101 to 103 are arranged at the center and three places on the left and right of the photographing screen 100. Focus detection pixels are linearly arranged in the longitudinal direction of the focus detection areas 101 to 103 indicated by rectangles. Normally, the user manually selects one of the focus detection areas 101 to 103 according to the composition.

  FIG. 3 is a front view showing a detailed configuration of the image sensor 212, and is an enlarged view of the vicinity of the focus detection area 101 at the center of the photographing screen shown in FIG. In FIG. 3, the vertical and horizontal directions (pixel rows and columns) correspond to the vertical and horizontal directions of the photographing screen 100 shown in FIG. The image sensor 212 includes an imaging pixel 310 including a green pixel (G), a blue pixel (B), and a red pixel (R), and a focus detection pixel 311. The focus detection area 101 (see FIG. 2) has a focus. The detection pixels 311 are arranged in the horizontal direction. The focus detection pixels 311 are arranged linearly and densely in rows where the green pixels (G) and blue pixels (B) of the imaging pixels 310 are to be arranged.

  As shown in FIG. 4, the imaging pixel 310 includes the microlens 10, the photoelectric conversion unit 11, and a color filter (not shown). There are three types of color filters, red (R), green (G), and blue (B), and the respective spectral sensitivities have the characteristics shown in FIG. In the image pickup device 212, image pickup pixels having red (R), green (G), and blue (B) color filters are arranged in a Bayer array.

As shown in FIG. 5, the focus detection pixel 311 includes a microlens 10 and a pair of photoelectric conversion units 12 and 13, and the photoelectric conversion units 12 and 13 are each semicircular.
The focus detection pixel 311 is not provided with a color filter in order to increase the amount of light, and its spectral characteristics include the spectral sensitivity characteristic of a photodiode that performs photoelectric conversion, and an infrared cut filter (
The spectral sensitivity characteristics (see FIG. 7) are combined with the spectral sensitivity characteristics (not shown), and the spectral sensitivity characteristics of the green pixel (G), red pixel (R), and blue pixel (B) shown in FIG. 6 are added. The spectral wavelength characteristic is a light wavelength region of sensitivity, and the light wavelength region of sensitivity of the green pixel (G), red pixel (R), and blue pixel (B) is included.

  The photoelectric conversion unit 11 of the imaging pixel 310 is designed so as to receive all the light beams passing through the exit pupil (for example, F1.0) of the bright interchangeable lens by the microlens 10. The pair of photoelectric conversion units 12 and 13 of the focus detection pixel 311 is designed in such a shape that the microlens 10 receives all the light beams passing through a specific exit pupil (for example, F2.8) of the interchangeable lens. .

  FIG. 8 is a cross-sectional view of the imaging pixel 310. In the imaging pixel 310, the microlens 10 is disposed in front of the imaging photoelectric conversion unit 11, and the shape of the photoelectric conversion unit 11 is projected forward by the microlens 10. The photoelectric conversion unit 11 is formed on the semiconductor circuit substrate 29, and a color filter (not shown) is disposed between the microlens 10 and the photoelectric conversion unit 11.

  FIG. 9 is a cross-sectional view of the focus detection pixel 311. In the focus detection pixel 311, the microlens 10 is disposed in front of the pair of photoelectric conversion units 12 and 13, and the shape of the photoelectric conversion units 12 and 13 is projected forward by the microlens 10. The pair of photoelectric conversion units 12 and 13 are formed on the semiconductor circuit substrate 29, and the microlens 10 is integrally and fixedly formed thereon by the manufacturing process of the semiconductor image sensor.

  FIG. 10 shows a configuration of a pupil division type phase difference detection type focus detection optical system using a microlens. In the figure, reference numeral 90 denotes an exit pupil set at a distance d in front of the microlens arranged on the planned imaging plane of the interchangeable lens 202 (see FIG. 1). The distance d is a distance determined according to the curvature, refractive index, distance between the microlens and the photoelectric conversion unit, and the like, and is referred to as “distance pupil distance” in this specification. 91 is an optical axis of the interchangeable lens 202, 50 and 60 are microlenses, (52 and 53) and (62 and 63) are photoelectric conversion units corresponding to the microlenses 50 and 60, and 72, 73, 82, and 83 are focus detections. The luminous flux for use.

  Reference numeral 92 denotes an area of the photoelectric conversion units 52 and 62 projected onto the exit pupil 90 by the microlenses 50 and 60, and is referred to as a “ranging pupil” in this specification. Reference numeral 93 denotes an area of the photoelectric conversion units 53 and 63 projected onto the exit pupil 90 by the microlenses 50 and 60, that is, a distance measuring pupil. In FIG. 10, the distance measuring pupils 92 and 93 are shown as elliptical regions for easy understanding, but in reality, the shapes of the photoelectric conversion units 52, 53, 62, and 63 are enlarged and projected.

  In FIG. 10, focus detection pixels (comprising a microlens 50 and a pair of photoelectric conversion units 52 and 53) on the optical axis 91 and adjacent focus detection pixels (a microlens 60 and a pair of photoelectric conversion units). 62, 63), but also in other focus detection pixels, the pair of photoelectric conversion units has a light beam that arrives at each microlens from a pair of distance measurement pupils 92, 93, respectively. Is received. The arrangement direction of the focus detection pixels is made to coincide with the arrangement direction of the pair of distance measuring pupils, that is, the arrangement direction of the pair of photoelectric conversion units.

The microlenses 50 and 60 are disposed in the vicinity of the planned imaging plane of the optical system, and the shape of the pair of photoelectric conversion units 52 and 53 disposed behind the microlens 50 disposed on the optical axis 91 is the same. Projection is performed on the exit pupil 90 separated from the microlenses 50 and 60 by the distance measurement pupil distance d, and the projection shape forms distance measurement pupils 92 and 93. The shape of the pair of photoelectric conversion units 62 and 63 disposed behind the micro lens 60 disposed adjacent to the micro lens 50 is projected onto the exit pupil 90 separated by the distance measuring pupil distance d, and the projection thereof. The shape forms distance measuring pupils 92 and 93. That is, the microlens of each pixel and the photoelectric conversion unit are arranged so that the projection shapes (ranging pupils 92 and 93) of the photoelectric conversion units of the focus detection pixels coincide on the exit pupil 90 at the distance measurement pupil distance d. The positional relationship is determined.

  The photoelectric conversion unit 52 outputs a signal corresponding to the intensity of the image formed on the microlens 50 by the focus detection light beam 72 that passes through the distance measuring pupil 92 and faces the microlens 50. The photoelectric conversion unit 53 outputs a signal corresponding to the intensity of the image formed on the microlens 50 by the focus detection light beam 73 that passes through the distance measuring pupil 93 and faces the microlens 50. Further, the photoelectric conversion unit 62 outputs a signal corresponding to the intensity of the image formed on the microlens 60 by the focus detection light beam 82 that passes through the distance measuring pupil 92 and faces the microlens 60. The photoelectric conversion unit 63 outputs a signal corresponding to the intensity of the image formed on the microlens 60 by the focus detection light beam 83 that passes through the distance measuring pupil 93 and faces the microlens 60.

  A large number of focus detection pixels described above are arranged in a straight line, and the output of a pair of photoelectric conversion units of each pixel is grouped into an output group corresponding to the distance measurement pupil 92 and the distance measurement pupil 93, whereby the distance measurement pupil 92 and Information on the intensity distribution of a pair of images formed on the focus detection pixel array by the focus detection light fluxes that respectively pass through the distance measuring pupil 93 is obtained. By applying an image shift detection calculation process (correlation calculation process, phase difference detection process), which will be described later, to this information, the image shift amount of a pair of images is detected by a so-called pupil division method. Further, by applying a predetermined conversion process to the image shift amount, the deviation of the current imaging plane (imaging plane at the focus detection position corresponding to the position of the microlens array on the planned imaging plane) with respect to the planned imaging plane (Defocus amount) is calculated.

  Here, in the focus detection apparatus using the pupil division type phase difference detection method, when a pair of images is detected by the pair of photoelectric conversion units of the focus detection pixels, an output leaks between the photoelectric conversion units. A problem that the detection accuracy of the image shift amount deteriorates due to occurrence of (crosstalk) will be described.

  In such a focus detection apparatus using the pupil division type phase difference detection method, when an image shift amount is δ, a pair of image functions corresponding to a pair of images are F (x) and F (x + δ). Then, the other image function F (x + δ) is displaced relative to the one image function F (x) in the x direction, and the image displacement amount δ is determined from the displacement amount when the two image functions match. Here, x indicates the position of the focus detection pixels in the arrangement direction. In this embodiment, the ratio obtained by dividing the output (crosstalk) leaking from one photoelectric conversion unit to the other photoelectric conversion unit by the output of one photoelectric conversion unit is defined as the crosstalk rate.

When the crosstalk rate from one photoelectric conversion unit is α, the image function G (x) detected by one photoelectric conversion unit is paired with the image function F (x) when there is no crosstalk. Is the sum of the image function F (x + δ) detected in step 1 multiplied by the crosstalk rate α, and the image function H (x) detected in one photoelectric conversion unit is the image function F (x + δ) in the case of no crosstalk. And the image function F (x) detected by the photoelectric conversion unit paired with the product of the crosstalk rate α.
G (x) = F (x) + α · F (x + δ),
H (x) = F (x + δ) + α · F (x) (1)
When image shift detection is performed using such a pair of image functions G (x) and H (x), the detected image shift amount is smaller than the true image shift amount δ.

  The causes of the occurrence of such crosstalk are as follows: (1) Inside the semiconductor substrate forming the photoelectric conversion part, electrons generated at the end and deep part of the photoelectric conversion part by the incident light diffuse to the peripheral photoelectric conversion part. (2) Light is reflected and propagated between the light shielding metal layer and the wiring metal layer formed on the semiconductor surface. (3) A part of the light incident on the focus detection pixel is reflected outside the focus detection pixel, and the reflected light is re-reflected by a cover glass or the like on the sensor package and incident on the surrounding imaging pixels. Can be considered.

  Further, crosstalk will be described in detail. FIG. 11 is a diagram for explaining the cause of the occurrence of crosstalk in the focus detection pixel, and shows a cross-sectional structure of the focus detection pixel. In FIG. 11, the focus detection pixel includes a microlens, a filter, a light shielding metal, a wiring metal, and a photodiode formed on a semiconductor substrate. Note that the focus detection pixel may not include a filter.

  In such a configuration, the cause (1) of the occurrence of crosstalk is that light incident on the photoelectric conversion unit (photodiode) is photoelectrically converted outside or at a deep part of the photodiode to generate electrons, and then the electrons diffuse. This is because they are mixed in different photoelectric conversion units of the same focus detection pixel adjacent to each other or photoelectric conversion units of surrounding focus detection pixels. The cause (2) of the occurrence of crosstalk is that the light incident on the focus detection pixel is reflected and propagated through the gap between the light shielding metal and the wiring metal, so that different photoelectric conversion units of the same focus detection pixel adjacent to each other and the surrounding focus detection By mixing with the photoelectric conversion part of the pixel. The cause of the occurrence of crosstalk (3) is that light incident on the focus detection pixel is reflected by a photodiode and emitted to the outside of the focus detection pixel, and then the sensor package cover glass, optical low-pass filter, red This is because the light is reflected by an outer cut filter or the like, and again enters and mixes with a different photoelectric conversion unit of the same focus detection pixel or a surrounding photoelectric conversion unit of the focus detection pixel.

  The causes (1) to (3) of the occurrence of crosstalk all change the degree of influence of the crosstalk due to the angle characteristics of the incident light, and the crosstalk tends to increase as the angle formed by the incident light and the optical axis of the microlens increases. It is in. Basically, a light beam that has passed through a distance measuring pupil (for example, 92 and 93 shown in FIG. 10) enters the photoelectric conversion unit of the focus detection pixel, but a light beam that generates crosstalk is an area other than the distance measuring pupil. Also enters the focus detection pixels.

  In general, the incident angle of the light beam passing through the periphery of the aperture stop of the photographing lens to the focus detection pixel is larger than the incident angle of the light beam passing through the center of the aperture opening to the focus detection pixel, and is greatly affected by crosstalk. To do. Since the amount of crosstalk changes in accordance with the aperture F value of the photographing lens in this way, the crosstalk ratio used for crosstalk correction is measured in accordance with the aperture opening F value of the photographing lens, and the amount of crosstalk depends on the aperture aperture F value. This is stored as data, and at the time of crosstalk correction, aperture aperture F value data at the time when focus detection signal data is acquired from the focus detection pixel is received from the lens drive control device 206 (see FIG. 1). Crosstalk correction is performed on the focus detection signal data output from the focus detection pixels using a crosstalk rate corresponding to the aperture opening F value data.

  Further, as for the cause (1) of the occurrence of crosstalk, the influence is larger in the case of long wavelength light (red) having a deep penetration depth into the semiconductor substrate. In order to correct such fluctuations in the crosstalk ratio due to the light wavelength in accordance with the spectral distribution characteristics of the incident light, the spectral characteristics of the crosstalk ratio are measured and stored in advance, and around the focus detection pixels. Based on the RGB output of the imaging pixel, the spectral distribution characteristic of the incident light beam to the focus detection pixel at the time of acquiring the focus detection signal data is obtained, and the spectral distribution (filter wavelength characteristic) of the pixel giving crosstalk, The crosstalk ratio used for crosstalk correction may be corrected based on the measured spectral distribution characteristic of the incident light and the stored spectral characteristic of the crosstalk ratio.

Regarding the cause of the occurrence of crosstalk (3), the light beam causing the crosstalk passes through the filter of the pixel that gives the crosstalk and the filter of the pixel that receives the crosstalk. The crosstalk rate varies depending on the wavelength. In order to correct such fluctuations in the crosstalk rate according to the spectral distribution characteristics of the incident light, the spectral distribution (filter wavelength characteristics) of the pixels giving the crosstalk and the spectral distribution (filter wavelength characteristics) of the pixels receiving the crosstalk ) For the focus detection at the time when the focus detection signal data is acquired based on the RGB output of the imaging pixels around the focus detection pixels. Obtain the spectral distribution characteristics of the incident light to the pixel, and the spectral distribution (filter wavelength characteristics) of the pixel that gives crosstalk, the spectral distribution of the pixels that receive crosstalk (filter wavelength characteristics), and the measured spectral distribution of incident light The crosstalk rate used for crosstalk correction may be corrected based on the characteristics and the spectral characteristics of the stored crosstalk rate.

  FIG. 12 is a flowchart illustrating an imaging operation of the digital still camera (imaging device) according to the embodiment. The body drive control device 214 starts this operation when a power switch (not shown) of the camera is turned on in step 100. In the next step 110, the image data of the imaging pixels are read out and displayed on the electronic viewfinder. In step 120, a pair of image data corresponding to the pair of images is read from the focus detection pixel array. Here, it is assumed that the user has selected a focus detection area by operating a focus detection area selection switch (not shown).

  In step 130, crosstalk correction processing is performed on the pair of image data read from the focus detection pixel array. This crosstalk correction process will be described later. In step 140, an image shift detection calculation process (correlation calculation process) is performed based on the pair of image data subjected to the crosstalk correction process, an image shift amount is calculated, and the image shift amount is further converted into a defocus amount. . Details of the correlation calculation process will be described later.

  In step 150, it is checked whether or not the focus is close, that is, whether or not the calculated absolute value of the defocus amount is within a predetermined value. If it is determined that the lens is not in focus, the process proceeds to step 160, the defocus amount is transmitted to the lens drive control device 206, the focusing lens 208 of the interchangeable lens 202 is driven to the in-focus position, and the process returns to step 110 and described above. repeat. Even when focus detection is impossible, the process branches to this step, a scan drive command is transmitted to the lens drive control device 206, the focusing lens 208 of the interchangeable lens 202 is driven to scan from infinity to the nearest point, and the process returns to step 110. The above operation is repeated.

  On the other hand, if it is determined that it is close to the in-focus state, the process proceeds to step 170, where it is determined whether or not a shutter release operation has been performed by a shutter button (not shown), and if it is determined that the shutter release operation has not been performed, the process returns to step 110 and described above. Repeat the operation. If it is determined that the shutter release operation has been performed, the process proceeds to step 180, where an aperture adjustment command is transmitted to the lens drive control device 206, and the aperture value of the interchangeable lens 202 is set to the control F value (the F value set by the user or automatically). ). When the aperture control is completed, the imaging device 212 performs an imaging operation, and the image data of all the imaging pixels of the imaging device 212 and the focus detection signal data of all the focus detection pixels are read out.

  In step 190, the image data at the focus detection pixel position is interpolated based on the focus detection signal data of the focus detection pixel and the image data of the surrounding imaging pixels. In step 200, the image data including the image data of the imaging pixels and the interpolated image data is stored in the memory card 219, and the process returns to step 110 to repeat the above-described operation.

Next, the crosstalk correction process in step 130 of FIG. 12 will be described. FIG. 13 is an explanatory diagram of crosstalk in the focus detection pixel 311. In the figure, the focus detection signal data output from the pair of photoelectric conversion units (12, 13) of the focus detection pixel 311 is A.
2 (h, v) and A1 (h, v). Here, h and v are variables for indicating the horizontal and vertical pixel positions in the two-dimensional pixel arrangement shown in FIG. 3, for example, A2 (h, v) and A1 (h, v) are h columns. A pair of focus detection signal data of focus detection pixels in the eye and the vth row is shown.

In FIG. 13, the crosstalk rate from the photoelectric conversion unit 12 to the photoelectric conversion unit 13 is β, and the crosstalk rate from the photoelectric conversion unit 13 to the photoelectric conversion unit 12 is α. The crosstalk rate is measured by using a prototype sensor in which one of the pair of photoelectric conversion units is shielded, or is measured by shielding a light beam received by one photoelectric conversion unit on the distance measuring pupil. (See FIG. 1). When the focus detection signal data output from the pair of photoelectric conversion units when there is no crosstalk is B2 (h, v) and B1 (h, v), the focus detection signal data affected by the crosstalk A2 (h, v) and A1 (h, v) are as follows.
A1 (h, v) = B1 (h, v) + β · B2 (h, v),
A2 (h, v) = B2 (h, v) + α · B1 (h, v) (2)

Assuming that the influence of the crosstalk is slight with respect to the original output, B2 (h, v) ≈A2 (h,
By substituting v), B1 (h, v) ≈A1 (h, v) into equation (2), focus detection signal data B2 (h, v), B1 ( h, v) is obtained as follows.
B1 (h, v) = A1 (h, v) −β · A2 (h, v),
B2 (h, v) = A2 (h, v) −α · A1 (h, v) (3)
Since the right side of the equation (3) is the focus detection signal data output from the photoelectric conversion unit and the predetermined crosstalk rate, the corrected focus detection signal data can be obtained by calculation according to the equation (3).

  As will be described later, the influence of the crosstalk depends on the incident angle of the incident light with respect to the focus detection pixel and the incident direction of the incident light with respect to the arrangement direction of the pair of photoelectric conversion units. It is determined as a function of the position of the pixel (distance from the center of the screen), and a pair of crosstalk rates for a pair of photoelectric conversion units are separately determined. By applying equation (3) to all pairs of focus detection signal data, crosstalk correction processing is performed.

Next, the image shift detection calculation process (correlation calculation process) in step 140 of FIG. 12 will be described. The pair of images detected by the focus detection pixels is a type that can maintain the image shift detection accuracy with respect to the light amount balance because the distance measurement pupil is displaced by the aperture of the lens and the light amount balance may be lost. The correlation calculation is performed. A correlation calculation is performed on the pair of data strings (B11 to B1M, B21 to B2M: M is the number of data) for which the crosstalk correction processing has been completed, using equation (4), and a correlation amount C (k) is calculated. .
C (k) = Σ | B1n · B2n + 1 + k−B2n + k · B1n + 1 | (4)
In equation (4), the Σ operation is accumulated for n, and the range taken by n is limited to the range in which B1n, B1n + 1, B2n + k, and B2n + 1 + k data exist according to the image shift amount k. The The image shift amount k is an integer and is a relative shift amount with the data interval of the data string as a unit.

As shown in FIG. 14 (a), the calculation result of the equation (4) shows that the correlation amount C (k) is the amount of shift with a high correlation between a pair of data (k = kj = 2 in FIG. 14 (a)). Minimal (the smaller the value, the higher the degree of correlation). The shift amount x that gives the minimum value C (x) with respect to the continuous correlation amount is obtained using the three-point interpolation method according to the equations (5) to (8).
x = kj + D / SLOP (5),
C (x) = C (kj) − | D | (6),
D = {C (kj-1) -C (kj + 1)} / 2 (7),
SLOP = MAX {C (kj + 1) -C (kj), C (kj-1) -C (kj)} (8)

Whether or not the shift amount x calculated by the equation (5) is reliable is determined as follows. As shown in FIG. 14B, when the degree of correlation between a pair of data is low, the value of the minimal value C (x) of the interpolated correlation amount increases. Therefore, when C (x) is equal to or greater than a predetermined threshold value, it is determined that the calculated shift amount has low reliability, and the calculated shift amount x is canceled. Alternatively, in order to normalize C (x) with the contrast of data, when the value obtained by dividing C (x) by SLOP that is proportional to the contrast is equal to or greater than a predetermined value, the reliability of the calculated shift amount Is determined to be low, and the calculated shift amount x is canceled. Alternatively, when SLOP that is a value proportional to the contrast is equal to or less than a predetermined value, it is determined that the subject has low contrast and the reliability of the calculated shift amount is low, and the calculated shift amount x is canceled.

  As shown in FIG. 14C, when the degree of correlation of a pair of data is low and there is no drop in the correlation amount C (x) between the shift ranges kmin to kmax, the minimum value C (x) is obtained. In such a case, it is determined that the focus cannot be detected.

The correlation calculation formula is not limited to the formula (4), and any correlation calculation formula may be used as long as the distance measurement pupil is displaced by the aperture of the lens and the light quantity balance is lost, so that the image shift detection accuracy can be maintained. . If it is determined that the calculated shift amount x is reliable, it is converted into the image shift amount shft by the equation (9).
shft = PY · x (9)
In the equation (9), PY is a detection pitch (a pitch of focus detection pixels). The image shift amount shft calculated by the equation (9) is multiplied by a predetermined conversion coefficient k to be converted into a defocus amount def.
def = k · shft (10)

<< Modification of Embodiment >>
In the imaging device 212 shown in FIG. 3, the example in which the focus detection pixels 311 are arranged in one row of the imaging pixel array is shown. However, as shown in FIG. May be.

16 and 17 are explanatory diagrams of crosstalk in the focus detection pixel array shown in FIG. The focus detection signal data output from the pair of photoelectric conversion units of the focus detection pixels in the h-th column and the v-th row are denoted by A1 (h, v) and A2 (h, v). FIG. 16 shows the position of the photoelectric conversion unit affected by the crosstalk, focus detection signal data A1 (h, v) of the photoelectric conversion unit, the position of the photoelectric conversion unit affected by the crosstalk, and the photoelectric conversion thereof. The focus detection signal data and the crosstalk rate βi (i = 0 to 7) are shown. FIG. 17 shows the position of the photoelectric conversion unit affected by the crosstalk, the focus detection signal data A2 (h, v) of the photoelectric conversion unit, and the position of the photoelectric conversion unit affected by the crosstalk. The focus detection signal data and the crosstalk rate αi (i = 0 to 7) of the photoelectric conversion unit are shown.

The focus detection data of the photoelectric conversion unit when there is no crosstalk is B1 (h + m, v + n), B
Assuming that 2 (h + m, v + n), the output data A1 (h, v) and A2 (h, v) affected by the crosstalk are as follows.
A1 (h, v) = B1 (h, v) + β0 · B2 (h, v) + β1 · B2 (h, v + 1) + β2 · B1 (h, v + 1) + β3 · B2 (h-1, v + 1) + β4 B2 (h-1, v) + β5B2 (h-1, v-1) + β6B1 (h, v-1) + β7B2 (h, v-1)
A2 (h, v) = B2 (h, v) + α0 · B1 (h, v) + α1 · B1 (h, v + 1) + α2 · B2 (h, v + 1) + α3 · B1 (h + 1, v + 1) + α4 · B1 (h + 1, v) + α5 · B1 (h + 1, v−1) + α6 · B2 (h, v−1) + α7 · B1 (h, v−1) (11)

Assuming that the influence of the crosstalk is slight with respect to the original output, B1 (h + m, v + n) ≈
By substituting A1 (h + m, v + n), B2 (h + m, v + n) ≈A2 (h + m, v + n) into the equation (11), focus detection signal data B1 (h, v) corrected by removing the influence of crosstalk , B
The calculation formula of 2 (h, v) is as follows.
B1 (h, v) = A1 (h, v) −β0 · A2 (h, v) −β1 · A2 (h, v + 1) −β2 · A1 (h, v + 1) −β3 · A2 (h−1 , v + 1) -β4 · A2 (h-1, v) -β5 · A2 (h-1,
v-1) -β6 · A1 (h, v-1) -β7 · A2 (h, v-1),
B2 (h, v) = A2 (h, v) −α0 · A1 (h, v) −α1 · A1 (h, v + 1) −α2 · A2 (h, v + 1) −α3 · A1 (h + 1, v + 1) -Α4 · A1 (h + 1, v) -α5 · A1 (h + 1, v-1) -α6 · A2 (h, v-1) -α7 · A1 (h, v-1) (12)

  The amount of crosstalk changes according to the distance between the photoelectric conversion units, and the crosstalk rate generally decreases as the distance between the photoelectric conversion units increases in the crosstalk correction. For example, in FIG. 15, β3 <β4.

  In the focus detection pixel array shown in FIG. 15, focus detection pixels having photoelectric conversion units of the same size are arrayed, but focus detection pixels having different size photoelectric conversion units may be arrayed. FIG. 18 is an explanatory diagram of crosstalk in the case where focus detection pixels having photoelectric conversion units having different sizes every other row are arranged, and corresponds to the crosstalk of the pixel arrangement shown in FIG. In the v-th row, focus detection pixels each having a photoelectric conversion unit having the same size as that in FIG. 16 are arranged. On the other hand, focus detection pixels having photoelectric conversion units smaller in size than the photoelectric conversion units of the focus detection pixels in the vth row are arranged in the (v−1) th and v + 1th rows. The focus detection signal data output from the pair of photoelectric conversion units of the focus detection pixels in the h-th column and the v-th row are denoted by A1 (h, v) and A2 (h, v).

FIG. 18 shows the position of the photoelectric conversion unit affected by the crosstalk, the focus detection signal data A1 (h, v) of the photoelectric conversion unit, the position of the photoelectric conversion unit affected by the crosstalk, and the photoelectric conversion unit. The focus detection signal data of the conversion unit and the crosstalk rate are represented by βi and βi ′. The crosstalk rate βi represents the influence of crosstalk that the photoelectric conversion units of the focus detection pixels in the h-th column and the v-th row receive from adjacent photoelectric conversion units of the same size, and the crosstalk rate βi ′. Represents the influence of crosstalk received from a small-sized photoelectric conversion unit located in the upper and lower rows of the focus detection pixels in the h-th column and the v-th row.

In such a focus detection pixel array, the focus detection signal data B1 (h, v) after correction of the photoelectric conversion units of the focus detection pixels in the h-th column and the v-th row are as follows.
B1 (h, v) = A1 (h, v) −β0 · A2 (h, v) −β1 ′ · A2 (h, v + 1) −β2 ′ · A1 (h, v + 1) −β3 ′ · A2 ( h-1, v + 1)-. beta.4.A2 (h-1, v)-. beta.5'.A2 (h-1, v-1)-. beta.6'.A1 (h, v-1)-. beta.7'.A2 (h , v-1) (13) Similarly, the focus detection signal data B2 (h, v) after correction of the other photoelectric conversion unit can also be calculated. Further, corrected focus detection signal data for a small size photoelectric conversion unit can be calculated in the same way.

The amount of crosstalk changes according to the size of the photoelectric conversion unit that generates crosstalk, and the crosstalk rate generally decreases as the size of the photoelectric conversion unit decreases in the above-described crosstalk correction. For example, in FIG. 18, the crosstalk ratio from the photoelectric conversion unit that generates focus detection signal data A1 (h, v) to the photoelectric conversion unit that generates focus detection signal data A1 (h, v + 1) is the focus detection The crosstalk rate β2 ′ from the photoelectric conversion unit that generates the signal data A1 (h, v + 1) to the photoelectric conversion unit that generates the focus detection signal data A1 (h, v) is smaller.

  In the imaging device 212 shown in FIG. 3, focus detection signal data B1 (h, v) and B2 (h, v) after crosstalk correction of a pair of photoelectric conversion units of the focus detection pixels in the h-th column and the v-th row. v) is obtained based on the focus detection signal data output from the paired photoelectric conversion units as shown in equation (3), but the focus detection signals of the photoelectric conversion units of the adjacent focus detection pixels It can also be obtained based on the data and image data output from the photoelectric conversion unit of the surrounding imaging pixels.

  FIG. 19 is an explanatory diagram of crosstalk in the case where focus detection pixels are arranged in GB rows (v rows) of the Bayer array and the upper and lower rows are RG imaging pixel arrays, and the pixels shown in FIG. Corresponds to an array. In the v-th row, focus detection pixels including a photoelectric conversion unit having the same size as that in FIG. 16 are arranged. In the (v-1) th and (v + 1) th rows, imaging pixels (RG) each having a photoelectric conversion unit having a size larger than the size of the photoelectric conversion unit of the focus detection pixel in the vth row are arranged. The focus detection signal data output from the pair of photoelectric conversion units of the focus detection pixels in the h-th column and the v-th row are denoted by A1 (h, v) and A2 (h, v). The image data output from the RG imaging pixels in the (v−1) th and (v + 1) th rows are R (h + m, v−1), G (h + m, v−1), R (h + m, v + 1), G ( h + m, v + 1).

FIG. 19 shows the position of the photoelectric conversion unit of the focus detection pixel affected by the crosstalk, the focus detection signal data A1 (h, v) of the photoelectric conversion unit, and the focus detection signal affected by the crosstalk. The position of the photoelectric conversion unit of the pixel and the imaging pixel, focus detection signal data and imaging data output from the photoelectric conversion unit, and crosstalk rates βi, γri, and γgi are shown. The crosstalk rate βi represents the influence of the crosstalk that the photoelectric conversion units of the focus detection pixels on the h-th column and the v-th row receive from adjacent photoelectric conversion units of the same size, and the crosstalk rate γri is Represents the influence of crosstalk received from the photoelectric conversion unit of the red imaging pixels located in the upper and lower rows of the focus detection pixels in the h-th and v-th rows, and the crosstalk rate γgi is expressed in the h-th row. , Represents the influence of crosstalk received from the photoelectric conversion unit of the green imaging pixels located in the upper and lower rows of the focus detection pixels in the v-th row.

In such a focus detection pixel array, the focus detection signal data B1 (h, v) after correction of the photoelectric conversion units of the focus detection pixels in the h-th column and the v-th row are as follows.
B1 (h, v) = A1 (h, v) −β0 · A2 (h, v) −γg1 · A2 (h + 1, v + 1) −γr
2 * R (h, v + 1)-[gamma] g3 * G (h-1, v + 1)-[beta] 4 * A2 (h-1, v)-[gamma] g5 * G (h-1, v-1)-[gamma] r6 * R (h, v-1) -γg7 · G (h + 1, v-1) (14) Similarly, the focus detection signal data B2 (h, v) after correction of the other photoelectric conversion unit can be calculated. it can.

The amount of crosstalk changes according to the wavelength sensitivity of the imaging pixel, and the crosstalk rate of the R pixel is generally larger than the crosstalk rate of the G pixel in the above-described crosstalk correction. For example, in FIG. 19, the crosstalk rate γr3 from the R pixel to the photoelectric conversion unit that generates the output data A1 (h + 1, v) is the crosstalk rate γr3 from the G pixel to the photoelectric conversion unit that generates the output data A1 (h, v). It becomes larger than the talk rate γg3.

  In the image sensor 212A illustrated in FIG. 15, the focus detection pixel 311 is provided with a pair of photoelectric conversion units in one pixel. However, like the image sensor 212B illustrated in FIG. 20, the focus detection pixel 313 is illustrated. , 314 may include one photoelectric conversion unit in one pixel. In FIG. 20, the focus detection pixel 313 and the focus detection pixel 314 are paired, and correspond to the focus detection pixel 311 shown in FIG.

  The focus detection pixel 313 includes the microlens 10 and the photoelectric conversion unit 16 as shown in FIG. Further, the focus detection pixel 314 includes the microlens 10 and the photoelectric conversion unit 17 as shown in FIG. The photoelectric conversion units 16 and 17 are projected onto the exit pupil of the interchangeable lens by the microlens 10 to form distance measuring pupils 92 and 93 shown in FIG. Therefore, an output of a pair of images used for focus detection can be obtained by the arrangement of the focus detection pixels 313 and 314. By providing one photoelectric conversion unit in the focus detection pixel, it is possible to avoid a complicated configuration of the signal readout circuit of the image sensor.

FIG. 22 is an explanatory diagram of the crosstalk of the image sensor 212B in which the focus detection pixels shown in FIGS. 21A and 21B are arranged, and corresponds to the crosstalk of the pixel arrangement shown in FIG. In the v-th row, the focus detection pixels shown in FIG. 21A are arranged in the photoelectric conversion unit having the same size as that in FIG. 16, and the surroundings are for focus detection shown in FIGS. 21A and 21B. Surrounded by pixels. The focus detection signal data output from the photoelectric conversion unit of the focus detection pixel in the h-th column and the v-th row is A1 (h, v).

FIG. 22 shows the position of the photoelectric conversion unit affected by the crosstalk, the focus detection signal data A1 (h, v) of the photoelectric conversion unit, the position of the photoelectric conversion unit affected by the crosstalk, and the photoelectric conversion unit. The focus detection signal data of the conversion unit and the crosstalk rates ηai and ηbi are shown. The crosstalk rate ηai represents the influence of crosstalk received by the photoelectric conversion units of the focus detection pixels in the h-th column and the v-th row from the photoelectric conversion units of the focus detection pixels shown in FIG. The talk rate ηbi represents the influence of crosstalk received by the photoelectric conversion unit of the focus detection pixel in the h-th column and the v-th row from the photoelectric conversion unit of the focus detection pixel shown in FIG.

In such a focus detection pixel array, the focus detection signal data B1 (h, v) after correction of the photoelectric conversion units of the focus detection pixels in the h-th column and the v-th row are as follows.
B1 (h, v) = A1 (h, v) −ηb0 · A2 (h + 1, v) −ηa1 · A1 (h + 1, v + 1)
-Ηb2 · A2 (h, v + 1) -ηa3 · A1 (h-1, v + 1) -ηb4 · A2 (h-1, v)
-Ηa5 · A1 (h-1, v-1) -ηb6 · A2 (h, v-1) -ηa7 · A1 (h + 1, v-1) (15)
Similarly, the focus detection signal data B2 (h + 1, v) after correction of the paired photoelectric conversion units can also be calculated.

  FIG. 23 is a diagram for explaining that the influence of crosstalk varies depending on the position of the focus detection pixel on the screen. A focus detection pixel 20 having a pair of photoelectric conversion units 22 and 23 on the optical axis 91 of the photographing lens, and a pair of photoelectric conversion units 32 and 33 located at a distance Z from the optical axis 91 are provided. The focus detection pixel 30 is shown, and the incident angle of the incident light beam to the focus detection pixel 30 is larger than the incident angle of the incident light beam to the focus detection pixel 20 (angle formed with the optical axis). The amount of crosstalk from the focus detection pixel and the imaging pixel is larger in the focus detection pixel 30. Further, the amount of crosstalk between a pair of photoelectric conversion units is equal in the case of the focus detection pixel 20 located on the optical axis, but in the case of the focus detection pixel 30 arranged outside the optical axis, The amount of crosstalk from the photoelectric conversion unit 33 close to the optical axis to the photoelectric conversion unit 32 far from the optical axis is larger than the amount of crosstalk from the photoelectric conversion unit 32 far from the optical axis to the photoelectric conversion unit 33 close to the optical axis. Become.

  Thus, when the amount of crosstalk changes according to the focus detection pixel position, the crosstalk rate is measured and stored according to the distance from the optical axis, and crosstalk correction is performed when crosstalk correction is performed. Crosstalk correction is performed using the crosstalk rate corresponding to the position (distance from the optical axis) of the focus detection pixel that outputs the focus detection signal data for performing the talk correction, and the crosstalk amount is photoelectrically converted with respect to the optical axis. When changing according to the positional relationship between the units, the crosstalk rate is measured and stored according to the positional relationship of the photoelectric conversion unit, and the photoelectric conversion unit used for the crosstalk correction when performing the crosstalk correction Crosstalk correction is performed using a crosstalk rate corresponding to the positional relationship.

Further, as described above, the light beam that generates crosstalk enters the focus detection pixel from a region other than the distance measuring pupil. Such a ray is defined by the size of the exit pupil of the photographing optical system and the distance of the exit pupil (distance from the focus detection pixel to the exit pupil on the optical axis), and the focus detection pixel 30 disposed outside the optical axis. In contrast, the crosstalk rate changes according to the exit pupil size and the exit pupil distance. In order to deal with such cases, the crosstalk rate used for crosstalk correction is measured according to the size of the exit pupil and the distance of the exit pupil, and stored as data corresponding to the size of the exit pupil and the exit pupil distance. In the case of crosstalk correction, the exit pupil size data and the exit pupil distance data at the time when the focus detection pixel data is acquired are received from the lens drive control device, and the exit pupil size data and the exit pupil distance are received. Crosstalk correction is performed on the focus detection signal data using a crosstalk rate corresponding to the data.

In the above-described crosstalk correction arithmetic expressions (12) to (15), the crosstalk correction is performed according to the output of the photoelectric conversion unit that is closest to the photoelectric conversion unit that receives the crosstalk correction. For this reason, it is possible to use the output of the light beam conversion unit located farther from the photoelectric conversion unit subjected to crosstalk correction for crosstalk correction. For example, in order to correct A1 (h, v) in FIG. 16, A1 (h-1, v-1), A1 (h + 1, v-1)
, A2 (h + 1, v-1), etc. can be used.

  In the imaging device 212 illustrated in FIG. 3, an example in which the imaging pixels include a Bayer color filter is shown, but the configuration and arrangement of the color filters are not limited to this, and complementary color filters (green: G, An arrangement of yellow: Ye, magenta: Mg, cyan: Cy) may be employed. Further, in the image sensor 212 shown in FIG. 3, an example in which a color filter is not provided in the focus detection pixel is shown. However, one of the color filters of the same color as the image pickup pixel, for example, a green filter is provided. Even in this case, the present invention can be applied.

  FIGS. 5 and 21 show examples in which the shape of the photoelectric conversion unit of the focus detection pixel is circular or semicircular, but the shape of the photoelectric conversion unit is not limited to this and may be other shapes. For example, the shape of the photoelectric conversion unit of the focus detection pixel may be an ellipse, a rectangle, or a polygon. When the imaging element has a focus detection pixel array including photoelectric conversion units having different shapes, the crosstalk rate corresponding to the shape of each photoelectric conversion unit is measured and stored, and crosstalk correction is performed. Crosstalk correction is performed by switching the crosstalk rate in accordance with the photoelectric conversion portion shape of the focus detection pixel.

  In the imaging device 212 shown in FIG. 3, the example in which the imaging pixels and the focus detection pixels are arranged in a dense square lattice arrangement is shown, but they may be arranged in a dense hexagonal lattice arrangement.

  The present invention can be applied to both a CCD image sensor and a CMOS image sensor.

  The image pickup apparatus of the present invention is not limited to a digital still camera or a film still camera in which the above-described interchangeable lens is detachably attached to the camera body, but is a lens-integrated digital still camera, film still camera, or video camera. It can also be applied to. Furthermore, the present invention can be applied to a small camera module built in a mobile phone, a surveillance camera, a robot visual recognition device, and the like. Furthermore, the present invention can be applied to a focus detection device other than a camera, a distance measuring device, a stereo distance measuring device, and the like.

11, 12, 13, 16, 17; photoelectric conversion unit, 202; interchangeable lens, 214; body drive control device, 212, 212A, 212B; imaging element, 310; imaging pixel, 311, 313, 314; Pixel

Claims (8)

A plurality of focus detection pixels having first and second photoelectric conversion units are arranged in a radial direction from the center of the photographing screen around the photographing screen, and a pair of light beams passing through the optical system form. A focus detection pixel array that receives an image by each of the first and second photoelectric conversion units and generates a pair of image signals;
The second crosstalk correction amount based on the output signal of the first photoelectric conversion unit and the first crosstalk rate resulting from the distance from the center of the shooting screen to the position of the second photoelectric conversion unit. Correcting the output signal of the photoelectric conversion unit, and the second crosstalk rate resulting from the output signal of the second photoelectric conversion unit and the distance from the center of the shooting screen to the position of the first photoelectric conversion unit; Correction means for correcting the output signal of the first photoelectric conversion unit with a crosstalk correction amount based on
An image shift detection unit that detects a shift amount of the pair of images based on the pair of image signals generated by the output signals of the first and second photoelectric conversion units corrected by the correction unit; ,
A focus detection unit that detects a focus adjustment state of the optical system based on a shift amount of the image detected by the image shift detection unit;
The distance between the first photoelectric conversion unit and the center of the shooting screen is greater than the distance between the second photoelectric conversion unit and the center of the shooting screen, and the second crosstalk rate is the first crosstalk rate. A focus detection device having a crosstalk ratio greater than The focus detection apparatus according to claim 1,
The focus detection pixel includes one microlens and a pair of photoelectric conversion units serving as the first and second photoelectric conversion units juxtaposed in an arrangement direction of the focus detection pixels. Focus detection device. The focus detection apparatus according to claim 1 or 2,
The focus detection apparatus characterized in that the correction means changes the crosstalk correction amount in accordance with a stop aperture F value of the optical system. The focus detection apparatus according to any one of claims 1 to 3,
An image sensor having a plurality of imaging pixels that are two-dimensionally arranged and receive a light beam passing through the optical system and output an output signal for imaging; and
The focus detection pixels are arranged in an array of the imaging pixels,
The correction unit corrects the output signals of the first and second photoelectric conversion units of the focus detection pixel with a crosstalk correction amount based on the output signals of the imaging pixels located around the focus detection pixel. An imaging apparatus characterized by that. The imaging apparatus according to claim 4,
The imaging pixel includes a plurality of types of pixels having sensitivity to different colors,
The image pickup apparatus, wherein the correction unit changes the crosstalk correction amount according to color sensitivity of the image pickup pixels located in the periphery. A plurality of imaging pixels that are two-dimensionally arranged and each have a photoelectric conversion unit that receives a light beam passing through the optical system and outputs an output signal for imaging;
A focus detection pixel having first and second photoelectric conversion units juxtaposed in a first direction so as to receive a pair of light fluxes passing through the optical system is disposed in the imaging pixel array. A plurality of focus detection pixel rows that are arranged in one direction and generate a pair of image signals corresponding to a pair of images formed by the pair of light beams;
The output signals of the first photoelectric conversion units of the focus detection pixels in the focus detection pixel column are respectively positioned on both sides of the first photoelectric conversion unit of the focus detection pixels with respect to the first direction. While correcting with the crosstalk correction amount based on each of the output signals of the photoelectric conversion unit and the crosstalk correction amount based on each of the output signals of the photoelectric conversion units of the plurality of imaging pixels in the vicinity of the focus detection pixel, The output signal of the second photoelectric conversion unit of the focus detection pixel is the output signal of the first photoelectric conversion unit located on both sides of the second photoelectric conversion unit of the focus detection pixel with respect to the first direction. Correction means for correcting with a crosstalk correction amount based on each of the above, and a crosstalk correction amount based on each of the output signals of the photoelectric conversion units of a plurality of imaging pixels in the vicinity of the focus detection pixel,
An image shift detection unit that detects a shift amount of the pair of images based on the pair of image signals generated by the output signals of the first and second photoelectric conversion units corrected by the correction unit; ,
A focus detection device comprising: a focus detection unit that detects a focus adjustment state of the optical system based on a shift amount of the pair of images detected by the image shift detection unit. The focus detection apparatus according to claim 6,
Of the first photoelectric conversion units located on both sides of the second photoelectric conversion unit of the focus detection pixel with respect to the first direction, the first photoelectric conversion unit disposed on the same focus detection pixel as the second photoelectric conversion unit. The crosstalk correction amount based on the output of one photoelectric conversion unit is different from the crosstalk correction amount based on the output of the first photoelectric conversion unit arranged in a focus detection pixel different from the second photoelectric conversion unit. Focus detection device. A plurality of imaging pixels that are two-dimensionally arranged and each have a photoelectric conversion unit that receives a light beam passing through the optical system and outputs an output signal for imaging;
A focus detection pixel having first and second photoelectric conversion units juxtaposed in a first direction so as to receive a pair of light fluxes passing through the optical system is disposed in the imaging pixel array. A plurality of focus detection pixel rows that are arranged in one direction and generate a pair of image signals corresponding to a pair of images formed by the pair of light beams;
The output signal of the first photoelectric conversion unit of the focus detection pixel of the focus detection pixel column is converted into the output signal of the second photoelectric conversion unit adjacent in the same focus detection pixel as the first photoelectric conversion unit. And correcting the output signal of the second photoelectric conversion unit of the focus detection pixel within the same focus detection pixel as that of the second photoelectric conversion unit. Correction means for correcting with a second crosstalk correction amount based on the output signal of the photoelectric conversion unit;
An image shift detection unit that detects a shift amount of the pair of images based on the pair of image signals generated by the output signals of the first and second photoelectric conversion units corrected by the correction unit; ,
A focus detection unit that detects a focus adjustment state of the optical system based on a shift amount of the pair of images detected by the image shift detection unit;
Storage means for storing a first crosstalk rate and a second crosstalk rate determined in advance;
The correction unit calculates the first crosstalk amount by multiplying the first crosstalk rate by the output of the second photoelectric conversion unit, and calculates the first crosstalk rate from the output signal of the first photoelectric conversion unit. The output signal of the first photoelectric conversion unit is corrected by subtracting the crosstalk amount of 1, and the output of the first photoelectric conversion unit is set to the second crosstalk rate by using the second crosstalk amount. A focus detection apparatus that calculates by multiplying and corrects the output signal of the second photoelectric conversion unit by subtracting the second crosstalk amount from the output signal of the second photoelectric conversion unit.

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