JP5769455B2 - Imaging device - Google Patents

Description

The present invention automatically directed to imaging equipment having an automatic focusing (AF) function for performing focus adjustment.

The imaging apparatus generally employs a contrast AF method as an AF function. This contrast AF method is disclosed in Patent Documents 1 and 2, for example. Patent Document 1 acquires a video signal from an image sensor while moving the position of a focus lens, searches for a focus lens position where an AF evaluation value (contrast value) calculated from the video signal is maximized, and performs focus adjustment control. Is disclosed.
In Patent Document 2, a plurality of photoelectric conversion elements for photographing and AF photoelectric conversion elements are arranged on an image pickup element to form a concavo-convex shape, and an AF photoelectric conversion element is disposed in each of a concave part and a convex part. It is disclosed that contrast AF is performed based on the difference between the output of the photoelectric conversion element for AF and the convex portion.

JP 2007-72254 A JP 2004-361611 A

However, in Patent Document 1 and a general contrast AF method, it is necessary to search for a focus lens position where the AF evaluation value is maximized, so that it takes a long time for focus adjustment to search for the focus lens position.
In Patent Document 2, since an AF photoelectric conversion element must be provided in addition to the photoelectric conversion element for photographing, the number of effective pixels for photographing is reduced, the aperture ratio is lowered, and the image quality of the photographed image is lowered. Resulting in.

An object of the present invention is intended to be made in order to solve the above problems, without reducing the quality of the captured image, and an object thereof is to provide an imaging equipment capable of performing high-speed focusing .

An imaging apparatus according to a main aspect of the present invention includes an imaging optical system in which an imaging lens group and a focusing lens group are arranged in the optical axis direction , a plurality of pixels, and the imaging lens group of the imaging optical system. Receiving an image from a subject through the focusing lens group , converting the subject image into each electrical signal for each of the plurality of pixels, and outputting the subject image corresponding to the output of the imaging device. In the imaging apparatus including a focusing unit that adjusts a focus by moving a focusing lens group of the imaging optical system in the optical axis direction based on contrast, the imaging element includes a plurality of microlenses corresponding to the pixels. a, the plurality of microlenses formed such that each of the plurality of the focal plane as the radius of curvature becomes larger closer to the imaging optical system Is, and the provided at different microlenses respectively positioned on the optical axis direction to form a plurality of image plane at different respective positions of said optical axis, said focusing means, the plurality of imaging of the imaging device The electric signals corresponding to the positions of the micro lenses provided in the optical axis direction among the electric signals corresponding to the image plane are input, and the contrast value based on the electric signals is input. A focusing direction, a front pin state, or a rear pin state are determined, and a moving direction of the focusing lens group in which the contrast value increases according to the in-focus state, the front pin state, or the rear pin state, which is the determination result If the result of the determination is the in-focus state, the focusing lens group is not moved. Along the optical axis to move the imaging lens group side, and moved to the imaging element side is referred to as in-focus state along the focusing lens unit as long as the rear focus state in the optical axis direction.

According to the present invention, without reducing the imaging quality, it is possible to provide an imaging equipment which can perform high-speed focusing.

1 is a schematic configuration diagram showing a first embodiment of an imaging apparatus according to the present invention. The block block diagram which shows the apparatus. The specific cross-section block diagram which shows the image pick-up element in the apparatus. The figure which shows the Bayer arrangement | sequence of the RGB pixel in the image pick-up element of the apparatus. The figure which shows each contrast value according to each microlens when it is in an in-focus state in the same apparatus. The figure which shows each contrast value according to each microlens when it exists in the front pin state in the same apparatus. The figure which shows each contrast value according to each microlens when it exists in a back pin state in the same apparatus. The imaging | photography operation | movement flowchart in the same apparatus. The AF process flowchart in the same apparatus. FIG. 5 is a specific cross-sectional configuration diagram illustrating an imaging element in a second embodiment of an imaging apparatus according to the present invention.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an imaging apparatus. The imaging device 1 includes an imaging optical system 50, an imaging element 21, and a liquid crystal display unit 29. The imaging optical system 50 includes an imaging lens group 51 and a focusing lens group 52, and condenses an optical image (subject image) from the subject on the imaging element 21. The focusing lens group 52 is movable along the optical axis direction Q of the imaging optical system 50.

FIG. 2 shows a block diagram of the apparatus 1. The apparatus 1 is equipped with a control unit 11 composed of a CPU. A focusing drive mechanism 30, a program / data storage unit 12, and an operation unit 13 are connected to the control unit 11. The control unit 11 is connected with an imaging processing unit 22, an SDRAM 23, an image processing unit 24, a compression / decompression unit 25, a recording / reproducing unit 26, and a display processing unit 28 via a bus 14. Yes. Among these, the imaging device 21 is connected to the imaging processing unit 22. An image storage unit 27 is connected to the recording / playback unit 26. A liquid crystal display unit 29 is connected to the display processing unit 28.
The operation unit 13 includes, for example, various input buttons such as a power button, a release button, a playback mode button, a moving image mode button, and a still image mode button. The operation unit 13 may be configured with a touch panel or the like.

The focusing drive mechanism 30 includes a motor and the like, and drives the focusing lens group 52 in the imaging optical system 50 in the optical axis direction Q.
The image sensor 21 captures the subject image collected through the imaging optical system 50, and outputs the subject image as an electrical signal (hereinafter referred to as an analog imaging signal). The image sensor 21 may be, for example, a CMOS image sensor or a CCD image sensor.

  FIG. 3 shows a specific cross-sectional configuration diagram of the image sensor 21. The imaging element 21 is formed by sequentially laminating a wiring layer 64, a light receiving element group 63, and a color filter 62 on the upper surface of a base 65, and further forming a microlens body 61 on the color filter 62. Here, assuming that the upper surface of the base 65 is an XY plane composed of XY directions and the optical axis direction Q of the imaging optical system 50 is a Z direction, the light receiving element group 63 places a plurality of light receiving elements 63e on the XY plane at regular intervals. It is formed in an array. Each of the light receiving elements 63e outputs an electrical signal corresponding to the amount of light received by the subject image collected by the imaging optical system 50. One pixel is formed by each of the light receiving elements 63e. Therefore, the imaging device 21 reads out each electric signal obtained by each light receiving element 63e in accordance with a predetermined reading order and outputs it as an analog imaging signal.

  The color filter 62 includes a plurality of filters 62r, 62g, and 62b of red (R), green (G), and blue (B). These filters 62r, 62g, and 62b are provided corresponding to the arrangement positions of the plurality of light receiving elements 63e, respectively. These filters 62r, 62g, and 62b follow a Bayer array including R pixels, G pixels, and B pixels as shown in FIG. That is, the color filter 62 is formed by grouping one R pixel, two G pixels, and one B pixel, and arranging these groups at regular intervals in the vertical and horizontal directions. Note that the cross-sectional configuration diagram of the image sensor 21 shown in FIG. 3 shows a WW cross section shown in FIG. 4.

  The microlens main body 61 is formed by integrally forming a plurality of microlenses 61a, 61b, 61c. These microlenses 61a, 61b, and 61c are provided corresponding to the arrangement positions of the plurality of light receiving elements 63e, respectively. These microlenses 61a, 61b, and 61c are provided with the respective positions of the spherical surfaces formed at the curvature radii R (R1, R2, and R3) being different in the optical axis direction Q. In the micro lens 61a, the distance between the tip of the spherical surface and the light receiving surface 63f of the light receiving element 63e is A. In the microlens 61b, the distance between the tip of the spherical surface and the light receiving surface 63f of the light receiving element 63e is B. In the microlens 61c, the distance between the tip of the spherical surface and the light receiving surface 63f of the light receiving element 63e is C. The relationship between these distances A, B, and C is that the distance A is the longest, then the distance B, then the distance C, and A> B> C.

In FIG. 4, the symbols “a”, “b”, and “c” are attached to the centers of one group of R pixel, G pixel, and B pixel. This corresponds to the distances A, B, C between the spherical tips of the microlenses 61a, 61b, 61c and the light receiving surface 63f of the light receiving element 63e. Therefore, one R pixel, two G pixels, and one B pixel of one group of the symbol “a” are all arranged by the microlenses 61a at the distance A between the tip of the spherical surface and the light receiving surface 63f of the light receiving element 63e. Has been. Note that each microlens 61a in one group of the symbol “a” is also referred to as a microlens group 61a. Similarly, one R pixel, two G pixels, and one B pixel of one group of reference “b” are all microlenses (micrometers) at a distance B between the tip of the spherical surface and the light receiving surface 63f of the light receiving element 63e. Lens group) 61b is arranged. One R pixel, two G pixels, and one B pixel of one group of reference “c” are all microlenses (microlens groups) having a distance C between the tip of the spherical surface and the light receiving surface 63f of the light receiving element 63e. 61c is arranged.
As shown in FIG. 4, for example, the micro lens groups 61a, 61b, 61c are repeatedly arranged in the order of the micro lens groups 61a, 61b, 61c in the horizontal direction, and the micro lens groups 61a, 61b, 61c in the vertical direction. It is arranged repeatedly in this order.

  Each of the micro lenses 61a, 61b, 61c is formed to have a different curvature radius R (R1, R2, R3). The curvature radii R (R1, R2, R3) of these microlenses 61a, 61b, 61c are expressed in other words as the distance between each microlens 61a, 61b, 61c and the light receiving surface 63f of each light receiving element 63e is longer. For example, the shorter the distance between each of the micro lenses 61a, 61b, 61c and the imaging optical system 50, the larger the lens. Among the microlenses 61a, 61b, 61c, the microlens 61a has the shortest distance to the imaging optical system 50, in other words, the microlens 61a has the longest distance to the light receiving surface 63f, and the next shortest is the microlens 61b. The next shortest is the microlens 61c. The radius of curvature of the microlens 61a is R1, the radius of curvature of the microlens 61b is R2, and the radius of curvature of the microlens 61c is based on the relationship between the distances between the microlenses 61a, 61b, and 61c and the imaging optical system 50 (or the light receiving surface 63f). The curvature radius is formed at R3, and these curvature radii R1, R2, and R3 have the largest curvature radius R1, then the curvature radius R2, then the curvature radius R3, and the relationship of R1> R2> R3 is satisfied. It has become.

With such microlenses 61a, 61b, 61c, when in focus, the focal position by the microlens 61b is on the light receiving surface 63f of the light receiving element 63e, and the focal position by the microlens 61a is the light receiving element 63e. The light receiving surface 63f is in front, that is, in the front pin state, and the focal position of the micro lens 61c is in the rear side, that is, in the rear pin state of the light receiving surface 63f of the light receiving element 63e.
Since each radius of curvature has a relation of R1>R2> R3, each light receiving element 63e has a high light collection efficiency, and each light receiving element 63e efficiently receives light that has passed through the imaging optical system 50. This is more effective when the subject has low luminance.
Further, by finely adjusting the set values of the curvature radii R1, R2, and R3, it is possible to finely adjust the focal position of the corresponding light receiving element 63e. For example, the focus detection accuracy can be improved by reducing the difference between the focal positions of the light receiving elements 63e corresponding to the curvature radii R1, R2, and R3.

  The imaging processing unit 22 performs various types of analog processing, such as reset noise reduction processing, waveform shaping processing, and gain control processing, on the analog imaging signal output from the image sensor 21, and the analog processed analog imaging signal is processed. It is converted into a digital signal (hereinafter referred to as imaging data). This imaging data is a digital image before image processing by the image processing unit 24, and is also called RAW data.

  The image processing unit 24 performs various types of image processing on the captured data to generate image data. The image processing unit 24 corresponds to, for example, an OB subtraction process for removing the influence of a dark current component in imaging data, a WB correction process for correcting the color balance of the imaging data, and one pixel corresponding to one color component. Image processing data is converted into image data in which one pixel corresponds to three color components, hue and saturation adjustment processing of the entire image data, gamma conversion processing for the image data, and color reproduction Processing, edge enhancement processing for enhancing edge components in the imaging data, and NR processing for removing noise components in the imaging data are performed.

The compression / decompression unit 25 performs still image compression processing such as the JPEG method or moving image compression processing such as the MPEG method on the image data obtained by the image processing unit 24 at the time of image recording. The compression / decompression unit 25 performs a decompression (decompression) process on the image data subjected to the compression process when the image is reproduced.
The recording / reproducing unit 26 records the image data obtained by the image processing unit 24 or the image data decompressed by the compression / decompression unit 25 in the image storage unit 27 at the time of image recording, and stores the image data at the time of image reproduction. The image data recorded in the unit 27 is read out and sent to the display processing unit 28.
The display processing unit 28 converts the image data obtained by the image processing unit 24 or the image data expanded by the compression / expansion unit 25 into a video signal and outputs the video signal to the liquid crystal display unit 29. The liquid crystal display unit 29 is, for example, a liquid crystal display (LCD), and displays an image based on the video signal from the display processing unit 28.

  The program / data storage unit 12 stores in advance a camera operation control program for comprehensively controlling the entire operation including the still image mode, the moving image mode, the reproduction mode, and the like of the apparatus 1. This camera operation control program includes a focusing control program for adjusting the focus by moving the focusing lens group 52 of the imaging optical system 50 in the optical axis direction Q based on the contrast of the subject image according to the output of the imaging device 21. This focusing control program causes the electrical signal corresponding to each microlens group 61a, 61b, 61c provided in the control unit 11 to be different from each other in the optical axis direction Q among the electrical signals output from the image sensor 21. And a determination function for determining the in-focus state, the front pin state, or the rear pin state from the contrast value based on these electrical signals, and the in-focus state, the front pin state, or the rear pin state determined by the determination function Thus, the moving direction of the focusing lens group 52 is determined, and a focusing function for adjusting the focus by moving the focusing lens group 52 in the determined moving direction on the optical axis direction Q is realized.

  The control unit 11 includes a focusing control unit 111 as a focusing unit by executing a camera operation control program stored in the program / data storage unit 12. The focusing control unit 111 moves the focusing lens group 52 of the imaging optical system 50 in the optical axis direction Q based on the contrast of the subject image corresponding to the analog imaging signal output from the imaging element 21, for example, the contrast value increases. The moving direction of the focusing lens group 52 is determined, and the focusing lens group 52 is moved in the determined moving direction to perform autofocus (AF) processing.

Specifically, the focusing control unit 111 takes in the imaging data analog-processed by the imaging processing unit 22, and the four corresponding to one R pixel, two G pixels, and one B pixel in the taken imaging data. Contrast values Ca, Cb, Cc for each group, that is, for each microlens 61a, 61b, 61c, are obtained from the data (RGB color information).
Note that when the subject has low luminance, the focusing control unit 111 captures the imaging data analog-processed by the imaging processing unit 22, and 4 corresponding to the RGB pixels in one group shown in FIG. 4 from the captured imaging data. Two pieces of data (RGB color information) may be extracted and added, and the contrast values Ca, Cb, and Cc for each group, that is, the microlenses 61a, 61b, and 61c may be obtained from the added data.

  The focusing control unit 111 determines the in-focus state, the front pin state, or the rear pin state from the respective contrast values Ca, Cb, Cc for each of the micro lenses 61a, 61b, 61c, and these in-focus state, front pin state, or rear The moving direction of the focusing lens group 52 is determined according to the pin state.

FIG. 5 shows the contrast values Ca, Cb, and Cc for each microlens 61a, 61b, and 61c with respect to the position of the light receiving surface (imaging surface) 63f of the light receiving element 63e in the focused state. The contrast value C indicates the highest value at the in-focus point, and sequentially decreases as the distance from the in-focus state increases. Accordingly, when in the in-focus state, the contrast value Cb obtained from each pixel of each group corresponding to each microlens 61b is the highest, and each contrast value Ca, Cc of each of the other microlenses 61a, 61c is the contrast. It becomes lower than the value Cb. 3 is in focus as described above, the focal position by the microlens 61b is on the light receiving surface 63f of the light receiving element 63e, and the focal position by the microlens 61a is in front of the light receiving surface 63f of the light receiving element 63e. Yes, the focal position of the microlens 61c is behind the light receiving surface 63f of the light receiving element 63e.
When in focus, the focusing control unit 111 holds the position of the focusing lens group 52 in the optical axis direction Q without moving the focusing lens group 52 along the optical axis direction Q of the imaging optical system 50.

FIG. 6 shows contrast values Ca, Cb, and Cc for each microlens 61a, 61b, and 61c with respect to the position of the light receiving surface (imaging surface) 63f of the light receiving element 63e in the front pin state. When in the front pin state, the contrast Cc value obtained from each pixel of each group corresponding to each microlens 61c is the highest, then the contrast value Cb of each microlens 61b, and then the contrast value of each microlens 61a. It decreases in the order of Ca.
When in the front pin state, the focusing control unit 111 moves the focusing lens group 52 from the front pin state to the in-focus state, that is, the imaging lens 52 along the optical axis direction Q as shown in FIG. Move to 21 side. The focusing control unit 111 moves the focusing lens group 52, and the contrast value Cb obtained from each pixel of each group corresponding to each microlens 61b is the highest, and the other microlenses 61a and 61c move. When the contrast values Ca and Cc are lower than the contrast value Cb, the position of the focusing lens group 52 in the optical axis direction Q is held.

FIG. 7 shows contrast values Ca, Cb, and Cc for each microlens 61a, 61b, and 61c with respect to the position of the light receiving surface (imaging surface) 63f of the light receiving element 63e in the rear pin state. When in the rear pin state, the contrast value Ca obtained from each pixel of each group corresponding to each microlens 61a is the highest, then the contrast Cb value of each microlens 61b, and then the contrast value of each microlens 61c. It decreases in the order of Cc.
When in the rear-pin state, the focusing control unit 111 takes the imaging lens 52 in the direction in which the focusing lens group 52 is brought into focus from the rear-pin state, that is, the focusing lens group 52 along the optical axis direction Q as shown in FIG. Move to the group 51 side. The focusing control unit 111 moves the focusing lens group 52 and, when in a focused state, holds the position of the focusing lens group 52 in the optical axis direction Q.

Next, the shooting operation of the imaging apparatus 1 configured as described above will be described with reference to the shooting operation flowchart shown in FIG.
When the power button of the operation unit 13 is operated and the power is turned on, the control unit 11 sets a recording flag indicating whether still image recording or moving image recording is OFF in step S1.
In step S2, the control unit 11 determines whether or not the playback button has been pressed. As a result of this determination, when the playback button is pressed, the control unit 11 moves to step S3 and sets the playback mode. In this reproduction mode, the control unit 11 issues an instruction to reproduce the image data to the recording / reproduction unit 26. The recording / reproducing unit 26 reads out the image data recorded in the image storage unit 27 and sends it to the display processing unit 28. The display processing unit 28 converts the image data obtained by the image processing unit 24 or the image data expanded by the compression / expansion unit 25 into a video signal and outputs the video signal to the liquid crystal display unit 29. Thereby, the liquid crystal display unit 29 displays an image based on the video signal from the display processing unit 28.

  In step S4, the control unit 11 determines whether or not the moving image button has been pressed. If the moving image button is pressed as a result of this determination, the control unit 11 proceeds to step S5, and reverses the recording flag and sets it to ON. If the moving image button is not pressed, the control unit 11 turns off the recording flag.

In step S6, the control unit 11 determines whether or not the recording flag is set to ON, that is, whether or not a moving image is being recorded. As a result of this determination, if the recording flag is off (OFF), the control unit 11 proceeds to step S7, and has the release button been pressed to make a transition from the off (OFF) state to the half-pressed (1st) state? Determine whether or not.
As a result of this determination, when the release button is shifted to the half-pressed (1st) state, the control unit 11 calculates the luminance of the subject from the AE process, that is, the imaging data obtained by the imaging processing unit 22 in step S8, and the shutter. Exposure conditions such as shutter speed data, aperture value data, and sensitivity are determined.
On the other hand, if it is determined in step S7 that the release button has not been pressed or is in an OFF state, the process returns to step S2 and the process is repeated.

  In step S9, the focusing control unit 111 of the control unit 11 moves the focusing lens group 52 of the imaging optical system 50 to the optical axis based on the AF processing, that is, the contrast of the subject image corresponding to the analog imaging signal output from the imaging device 21. The moving direction of the focusing lens group 52 that moves in the direction Q, for example, the contrast value becomes high, is determined, and the focusing lens group 52 is moved in the determined moving direction to perform autofocus (AF) processing.

Next, AF processing will be described according to the AF processing flowchart shown in FIG.
In step S20, the focusing control unit 111 captures the imaging data analog-processed by the imaging processing unit 22, and the four corresponding to one R pixel, two G pixels, and one B pixel in the captured imaging data. Contrast values Ca, Cb, Cc for each group, that is, for each microlens 61a, 61b, 61c, are obtained from the data (RGB color information).
Note that when the subject has low luminance, the focusing control unit 111 captures the imaging data analog-processed by the imaging processing unit 22, and 4 corresponding to the RGB pixels in one group shown in FIG. 4 from the captured imaging data. Two pieces of data (RGB color information) may be extracted and added, and the contrast values Ca, Cb, and Cc for each group, that is, the microlenses 61a, 61b, and 61c may be obtained from the added data.

  In step S21, the focusing control unit 111 determines whether or not the in-focus state is obtained from the contrast values Ca, Cb, and Cc for each of the microlenses 61a, 61b, and 61c. As a result of this determination, as shown in FIG. 5, the contrast value Cb obtained from each pixel of each group corresponding to each microlens 61b is the highest, and the contrast values Ca and Cc of the other microlenses 61a and 61c are the same. If the contrast value Cb is lower than the contrast value Cb and the contrast values Cc and Cb are in a predetermined relationship, for example, equal, and the difference is within the predetermined value, the focusing control unit 111 determines that it is in focus.

At this time, as shown in FIG. 3, the focal positions of the microlenses 61a, 61b, and 61c are such that the focal position of the microlens 61b is on the light receiving surface 63f of the light receiving element 63e, and the focal position of the microlens 61a is the light receiving element 63e. The focal position of the microlens 61c is behind the light receiving surface 63f of the light receiving element 63e.
When in the in-focus state, the focusing control unit 111 moves to step S22 and moves the focusing lens group 52 in the optical axis direction Q of the focusing lens group 52 without moving the focusing lens group 52 along the optical axis direction Q of the imaging optical system 50. Hold. Then, the focusing control unit 111 ends the AF process.

  On the other hand, if it is not the in-focus state but the state of either the front pin state or the rear pin state, the focusing control unit 111 determines the contrast values Ca, Cb for the respective microlenses 61a, 61b, 61c in step S23. , Cc, it is determined whether the state is the front pin state or the rear pin state.

For example, as shown in FIG. 6, each contrast value Ca, Cb, Cc for each microlens 61a, 61b, 61c has the highest contrast Cc value obtained from each pixel of each group corresponding to each microlens 61c, Next, if the contrast value Cb of each microlens 61b and then the contrast value Ca of each microlens 61a decrease in this order, the focusing control unit 111 determines that the state is the front pin state.
When the focusing control unit 111 is in the front pin state, in step S24, the focusing lens group 52 is moved from the front pin state to the in-focus state, that is, the focusing lens group 52 is moved along the optical axis direction Q on the image sensor 21 side. Move to. The focusing lens group 52 moves to be in focus, that is, in step S21, the contrast value Cb obtained from each pixel of each group corresponding to each microlens 61b becomes the highest, and each of the other microlenses 61a and 61c If it is determined that the contrast values Ca and Cc are lower than the contrast value Cb, the process proceeds to step S22, and the position of the focusing lens group 52 in the optical axis direction Q is held.

Further, as shown in FIG. 7, the contrast values Ca, Cb, and Cc for the respective microlenses 61a, 61b, and 61c have the highest contrast Ca value obtained from each pixel of each group that corresponds to each microlens 61a. Next, if the contrast value Cb of each microlens 61b and then the contrast value Cc of each microlens 61c are decreased in this order, the focusing control unit 111 determines that the rear pin state exists.
When the focusing control unit 111 is in the rear pin state, in step S25, the focusing lens group 52 is moved from the rear pin state to the in-focus state, that is, the focusing lens group 52 is moved to the imaging lens 51 side along the optical axis direction Q. Move to. The focusing lens group 52 moves to be in focus, that is, in step S21, the contrast value Cb obtained from each pixel of each group corresponding to each microlens 61b becomes the highest, and each of the other microlenses 61a and 61c If it is determined that the contrast values Ca and Cc are lower than the contrast value Cb, the process proceeds to step S22, and the position of the focusing lens group 52 in the optical axis direction Q is held.
Thus, the operation of the AF process shown in FIG. 9 is finished, and the process returns to the photographing operation flowchart shown in FIG.

When the release button is changed from the half-pressed (1st) state to the fully-pressed (2st) state in the in-focus state, the control unit 11 proceeds to step S12 and opens the shutter to take a still image. At the time of shooting this still image, the control unit 11 uses exposure conditions such as shutter speed data, aperture value data, and sensitivity determined by the AE process in step S8.
Further, the control unit 11 performs the following processing. That is, the imaging processing unit 22 inputs an analog imaging signal output from the imaging element 21. This analog image pickup signal is obtained by reading out each electric signal obtained by each light receiving element 63e of the image pickup element 21 according to a predetermined reading order. The imaging processing unit 22 performs various types of analog processing, such as reset noise reduction processing, waveform shaping processing, and gain control processing, on the input analog imaging signal, and converts them into imaging data.

  The image processing unit 24 corresponds to, for example, an OB subtraction process for removing the influence of the dark current component in the imaging data, a WB correction process for correcting the color balance of the imaging data, and one pixel corresponding to one color component. Image data that is converted into image data in which one pixel corresponds to three color components, processing for adjusting the hue and saturation of the entire image data, gamma conversion processing for the image data, and color reproduction processing Then, image data is generated by performing edge enhancement processing for enhancing edge components in imaging data, NR processing for removing noise components in imaging data, and the like.

The compression / decompression unit 25 performs still image compression processing such as the JPEG method or moving image compression processing such as the MPEG method on the image data obtained by the image processing unit 24 at the time of image recording.
The recording / playback unit 26 records the image data obtained by the image processing unit 24 or the image data expanded by the compression / expansion unit 25 in the image storage unit 27 when the image is recorded.
Then, after taking a still image, the control unit 11 proceeds to step S10.
If the release button is not fully pressed (2st) as a result of the determination in step S11, the control unit 11 returns to step S2 and repeats the process.

As a result of the determination in step S6, if the recording flag is on (ON), the control unit 11 proceeds to step S13 to perform AE processing, proceeds to step S14, and performs focusing control in the same manner as in step S9. The AF processing flowchart shown in FIG. 9 is executed by the unit 111 to perform the AF processing.
Thereafter, in step S15, the control unit 11 starts moving image shooting and proceeds to step S10.
In step S10, the control unit 11 determines whether or not the power button is operated to turn off the power. If the power is not turned off, the control unit 11 returns to step S2, and ends when the power is turned off.

  As described above, according to the first embodiment, each of the plurality of light receiving elements 63e is provided corresponding to each arrangement position, and each spherical surface is formed at each of the curvature radii R1, R2, and R3. In addition, the distance between the tip of the spherical surface and each light receiving surface 63f of each light receiving element 63e is A, B, C, respectively, and the relationship between these distances A, B, C is A> B> C. , 61c is provided, so that high-speed focus adjustment can be performed without deteriorating the image quality.

  That is, since it is possible to determine whether the in-focus state, the front pin state, or the rear pin state from the contrast values Ca, Cb, and Cc for each microlens 61a, 61b, and 61c, the in-focus state can be determined from the determination result. For example, if the focusing lens group 52 is not moved and is in the front pin state, the focusing lens group 52 is moved to the imaging lens group 51 side, and if it is in the rear pin state, the focusing lens group 52 is moved to the imaging element 21 side. Then, immediately after determining the front pin state or the rear pin state, the focusing lens group 52 can be moved in the focusing direction, and high-speed focus adjustment can be realized.

  In the AF process, for example, a contrast value is acquired while moving the focusing lens group 52 by a hill-climbing method, and the contrast value indicating the maximum value is detected as the in-focus position. Until the in-focus position is detected, the AF process is performed. Further, when the focusing lens group 52 is moved in one direction and a focus position candidate is detected, a process of moving the focusing lens group 52 in the reverse direction to determine the focus position candidate as the focus position is performed. . On the other hand, in the present apparatus 1, the moving direction of the focusing lens group 52 can be determined from the determination result of the in-focus state, the front pin state, or the rear pin state based on the contrast values Ca, Cb, and Cc. AF processing can be performed at high speed.

When performing the AF process, four data corresponding to RGB pixels in one group shown in FIG. 4 are extracted from the imaging data analog-processed by the imaging processing unit 22 and added, and each microlens is added from the added data. Since the contrast values Ca, Cb, and Cc for each of 61a, 61b, and 61c are obtained, the processing time required to obtain these contrast values Ca, Cb, and Cc can be shortened. In addition, since the contrast values Ca, Cb, and Cc include color information of RGB pixels, the contrast values coincide with image data acquired by photographing the subject, and accurate AF processing can be performed.
In particular, when the subject has low luminance, four data corresponding to RGB pixels in one group at the same distances A, B, and C shown in FIG. 4 are extracted and added to each microlens 61a, 61b, 61c. Since different contrast values Ca, Cb, and Cc are obtained, accurate AF is possible even if the subject has low luminance.

When photographing the subject and acquiring the image data, the color information of the RGB pixels of all the pixels of the image sensor 21 is used, so that the aperture efficiency can be improved and the image quality can be improved without reducing the number of pixels used for photographing. Can be improved.
Since the contrast values Ca, Cb, and Cc for each of the microlenses 61a, 61b, and 61c are obtained from the four RGB color information corresponding to the RGB pixels of the image sensor 21, the image obtained by photographing the subject as described above. The contrast value coincides with the data, and it is not necessary to correct the contrast values Ca, Cb, and Cc with respect to the change in the aperture diameter of the imaging lens group 51. In addition, a sufficient amount of light can be obtained even if the subject has low brightness. It can be ensured and accurate contrast values Ca, Cb, Cc can be obtained.

Next, a second embodiment of the present invention will be described with reference to the drawings. The difference from the first embodiment will be described.
FIG. 10 shows a specific cross-sectional configuration diagram of the image sensor 21. The microlens main body 61 is formed by integrally forming a plurality of microlenses 61a, 61b, 61c. These microlenses 61a, 61b, and 61c are formed to have the same curvature radius Ra.
With such microlenses 61a, 61b, 61c, when in focus, the focal position by the microlens 61b is on the light receiving surface 63f of the light receiving element 63e, and the focal position by the microlens 61a is the light receiving element 63e. The light receiving surface 63f is in front, that is, in the front pin state, and the focal position of the micro lens 61c is in the rear side, that is, in the rear pin state of the light receiving surface 63f of the light receiving element 63e.

Next, the AF process will be described with reference to the AF process flowchart shown in FIG.
In step S20, the focusing control unit 111 captures the imaging data analog-processed by the imaging processing unit 22, and the four corresponding to one R pixel, two G pixels, and one B pixel in the captured imaging data. Contrast values Ca, Cb, Cc for each group, that is, for each microlens 61a, 61b, 61c, are obtained from the data (RGB color information). When the subject has low luminance, the focusing control unit 111 takes in the imaging data analog-processed by the imaging processing unit 22, and four data corresponding to the RGB pixels in one group shown in FIG. 4 from the acquired imaging data. (RGB color information) may be extracted and added, and the contrast values Ca, Cb, Cc for each group, that is, for each microlens 61a, 61b, 61c may be obtained from this added data.

  In step S21, the focusing control unit 111 determines whether or not the in-focus state is obtained from the contrast values Ca, Cb, and Cc for each of the microlenses 61a, 61b, and 61c. If the result of this determination is that the subject is in focus, the focusing control section 111 moves to step S22, and the focusing lens group 52 does not move along the optical axis direction Q of the imaging optical system 50, and the light of the focusing lens group 52 is moved. Holds the position in the axial direction Q.

On the other hand, if not in focus, the focusing control unit 111 determines in step S23 either the front pin state or the back pin state from the contrast values Ca, Cb, Cc for each microlens 61a, 61b, 61c. It is determined whether it is.
If the result of this determination is that the lens is in the front pin state as shown in FIG. 6, the focusing control unit 111 changes the focusing lens group 52 from the front pin state to the in-focus state in step S24 when in the front pin state. That is, the focusing lens group 52 is moved along the optical axis direction Q to the imaging lens group 51 side.
As shown in FIG. 7, in the rear pin state, in step S25, the focusing control unit 111 changes the focusing lens group 52 from the rear pin state to the focused state, that is, the focusing lens group 52 in the optical axis direction Q. Along the image sensor 21 side.

As described above, according to the second embodiment, each of the plurality of light receiving elements 63e is provided corresponding to each arrangement position, and each spherical surface is formed at the same curvature radius Ra. A plurality of microlenses 61a, 61b, and 61c having distances A, B, and C between the front end and each light receiving surface 63f of each light receiving element 63e and A>B> C being the relationship between these distances A, B, and C are provided. Even if provided, the same effect as the first embodiment can be obtained.
Further, since each of the micro lenses 61a, 61b, 61c is formed to have the same curvature radius Ra, it has an advantage that it can be manufactured more easily.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
The plurality of microlenses 61a, 61b, 61c may be provided in at least two different positions in the optical axis direction Q.

  1: imaging device, 11: control unit, 12: program / data storage unit, 13: operation unit, 14: bus, 21: imaging device, 22: imaging processing unit, 23: SDRAM, 24: image processing unit, 25: Compression / decompression unit, 26: recording / playback unit, 28: display processing unit, 27: image storage unit, 29: liquid crystal display unit, 30: focusing drive mechanism, 50: imaging optical system, 51: imaging lens group, 52: focusing Lens group, 61: Micro lens body, 61a, 61b, 61c: Micro lens, 62: Color filter, 63: Light receiving element group, 63e: Light receiving element, 62r, 62g, 62b: Filter, 63f: Light receiving surface of light receiving element, 64: wiring layer, 65: base, 111: focusing control unit.

Claims (6)

An imaging optical system comprising an imaging lens group and a focusing lens group arranged in the optical axis direction ;
A plurality of pixels are formed, and an image from a subject is received from the imaging lens group of the photographing optical system through the focusing lens group , and the subject image is converted into each electrical signal for each of the plurality of pixels and output. An image sensor;
Focusing means for adjusting the focus by moving the focusing lens group of the imaging optical system in the optical axis direction based on the contrast of the subject image according to the output of the imaging element;
In an imaging apparatus comprising:
The image sensor has a plurality of microlenses corresponding to the pixels,
The plurality of microlenses are formed so that the radius of curvature increases as the plurality of imaging planes are closer to the photographing optical system, and the positions of the microlenses are different from each other in the optical axis direction. Forming a plurality of imaging planes at different positions in the optical axis direction;
The focusing means corresponds to the electrical signals corresponding to the positions of the microlenses provided differently in the optical axis direction among the electrical signals corresponding to the plurality of imaging planes of the imaging element. And determining the in-focus state, the front pin state, or the rear pin state from the contrast value based on these electrical signals, and depending on the in-focus state, the front pin state, or the rear pin state as the determination result The moving direction of the focusing lens group in which the contrast value becomes high is determined, and as a result of the determination, the focusing lens group is not moved if in the in-focus state, and the focusing lens group is determined in the front pin state. When moving to the imaging lens group side along the optical axis direction and in the rear pin state, the focusing lens group is moved along the optical axis direction. And focus state moves toward the image element side,
An imaging apparatus characterized by that.   The imaging device according to claim 1, wherein the plurality of microlenses are provided at at least two different positions in the optical axis direction. The plurality of microlenses are provided by grouping the microlenses having the same position in each optical position in the optical axis direction, and arranging the groups in a plurality of vertical and horizontal directions. The imaging device according to claim 1 . The imaging apparatus according to claim 3 , wherein each group includes a microlens corresponding to an RGB pixel . The focusing means adds the data of the RGB pixels for each of the groups having different positions in the optical axis direction when the subject has low luminance, and the positions of the RGB data differ from the added data in the optical axis direction. The imaging apparatus according to claim 3 , wherein the contrast values corresponding to the microlenses are obtained . The position of each of the plurality of microlenses is formed such that the greater the radius of curvature, the longer the distance between the microlens and the light receiving surface of the light receiving element formed on the imaging element. Item 2. The imaging device according to Item 1.

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