JP2019074634A - Imaging apparatus - Google Patents

Abstract

To obtain higher focus detection accuracy in an imaging apparatus that can detect a focus by use of an imaging sensor and detect a focus by use of a focus detection sensor.SOLUTION: An imaging apparatus has: an imaging sensor 112 which photo-electrically converts a first subject image of a pair obtained by dividing a beam from an imaging optical system to generate a pair of first focus detection image signals and which captures the subject image formed by the beam; a focus detection unit 5110 which is disposed separately from the imaging sensor and which photo-electrically convert a second subject image of the pair obtained by dividing the beam from the imaging optical system to generate a pair of second focus detection image signals; and control means 6122 which controls a focus of the imaging optical system by use of at least one of the first and second focus detection image signals. The control means determines reliability of the second focus detection image signal depending on the results after comparing a plurality of first focus detection image signals acquired from a plurality of regions in the imaging sensor for focus control.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an imaging device that performs focus detection by a phase difference detection method.

  The phase difference detection method uses the focus detection sensor provided exclusively for focus detection separately from the imaging sensor and the method using the imaging sensor in combination as a focus detection sensor. There is. In Patent Document 1, the focus lens is moved according to the focus detection result by the focus detection sensor, and the focus lens is moved using the contrast information which is obtained from the imaging sensor before the movement of the focus lens is completed. An imaging device for obtaining a focused state is disclosed. Further, Patent Document 2 discloses an imaging apparatus for selecting a focus detection method to be used according to the "photographing condition of a subject" such as a dark subject or a large defocus amount among the above two focus detection methods. ing.

JP, 2011-013324, A Patent No. 4349407 gazette

  In the imaging apparatus disclosed in Patent Document 1, two focus detection methods are switched in stages and used, but such switching of the focus detection methods is not necessarily appropriate. Also, in the imaging device disclosed in Patent Document 2, the focus detection method to be used is selected according to the "shooting condition of the subject", but the focus detection method to be used based on the actual signals indicating the respective focus detection results There are cases where higher focus detection accuracy can be obtained by selecting.

  The present invention provides an imaging apparatus capable of performing focus detection using an imaging sensor and focus detection using a focus detection sensor and obtaining higher focus detection accuracy.

  An imaging apparatus according to an aspect of the present invention photoelectrically converts a first subject image of a pair obtained by dividing a light beam from an imaging optical system to generate a first focus detection image signal of the pair, and An imaging sensor for imaging an object image formed by a light flux and an imaging sensor are provided separately, and photoelectric conversion is performed on a second object image of the pair obtained by dividing the light flux from the imaging optical system And a control unit that performs focus control of the imaging optical system using at least one of the first and second focus detection image signals. The control means determines the reliability of the second focus detection image signal according to the result of comparing the plurality of first focus detection image signals acquired from the plurality of areas in the imaging sensor, and focusing based on the determination result. It is characterized by performing control.

  The control method according to another aspect of the present invention photoelectrically converts a pair of first object images obtained by dividing a light beam from the imaging optical system to generate a pair of first focus detection image signals. And an imaging sensor for imaging an object image formed by the light flux and an imaging sensor separately provided, and photoelectrically converting a pair of second object images obtained by dividing the light flux from the imaging optical system. An imaging apparatus having a focus detection unit that generates a pair of second focus detection image signals performs focus control of the imaging optical system using at least one of the first and second focus detection image signals. The control method comprises the steps of: acquiring a plurality of first focus detection image signals from a plurality of regions in an imaging sensor; and a second focus detection image signal according to a result of comparing the plurality of first focus detection image signals And a step of performing focus control based on the determination result.

  A focus control program, which is a computer program that causes a computer of an imaging apparatus to execute focus control according to the above control method, also constitutes another aspect of the present invention.

  According to the present invention, in an imaging apparatus capable of focus detection using an imaging sensor and focus detection using a focus detection unit (focus detection sensor), focus detection and focus control can be performed with higher accuracy.

3 is a flowchart showing an AF process performed in the camera which is Embodiment 1 of the present invention. FIG. 2 is a diagram showing the entire configuration of an imaging sensor and the configuration of one pixel in Embodiment 1. FIG. 2 is a diagram showing a configuration of a pixel unit of the imaging sensor in Embodiment 1. FIG. 6 is a diagram for explaining phase difference detection focus detection in the first embodiment. FIG. 2 is a cross-sectional view showing a configuration of a camera having an optical finder in Embodiment 1. The block diagram which shows the structure of the said camera. FIG. 2 shows a configuration of a focus detection unit in Embodiment 1. FIG. 6 is a diagram for explaining an error factor of focus detection in the first embodiment. FIG. 6 is a diagram showing focus detection timing in the first embodiment. FIG. 6 is a diagram comparing the sizes of focus detection pixels and line sensor pixels in the first embodiment. FIG. 6 is a diagram for explaining the occurrence of an error factor in the first embodiment. Sectional drawing of the camera provided with the EVF finder in Example 2 of this invention. FIG. 7 is a block diagram showing the configuration of a camera of Example 2;

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2A shows the entire configuration of an imaging sensor 112 provided in an imaging apparatus according to an embodiment of the present invention. The imaging sensor 112 is configured by an imaging element such as a CCD sensor or a CMOS sensor. The imaging sensor 112 includes a pixel unit 201 in which a plurality of pixels are arranged in a two-dimensional array, a vertical selection circuit 202 which selects a pixel row in the pixel unit 201, and a horizontal selection circuit which selects a pixel column in the pixel unit 201. And 204. The vertical selection circuit 202 sequentially selects pixel rows in the pixel unit 201.

  Further, the imaging sensor 112 has a readout circuit 203 that reads out a signal (pixel signal) from the pixel of the pixel column selected by the vertical selection circuit 202. The readout circuit 203 has a memory for accumulating pixel signals, a gain amplifier, an AD converter, and the like for each pixel column. The horizontal selection circuit 204 sequentially selects the pixel signals read by the reading circuit 203 for each pixel column. Furthermore, the imaging sensor 112 also includes a serial interface 205 for specifying the operation mode and the like of each circuit from the outside.

  The imaging sensor 112 includes, in addition to the illustrated components, a timing generator that supplies timing signals to the vertical selection circuit 202, the horizontal selection circuit 204, the readout circuit 203 and the like, and a control circuit that controls these circuits.

  FIG. 2B shows the configuration of one pixel 206 of the imaging sensor 112. The pixel 206 has one micro lens 207 for dividing the incident light flux, and two photodiodes (hereinafter referred to as PD) 208 and 209 for receiving each of the divided light flux. Two (a pair of) PDs 208 and 209 are provided to cause the pixel 206 to function as a focus detection pixel for performing focus detection in the phase difference detection method. Focus detection in a phase difference detection method using the imaging sensor 112 is referred to as imaging surface focus detection, and drive of a focus lens based on the result (that is, AF as focus control) is referred to as imaging surface phase difference AF.

  The pixel 206 further includes a pixel amplification amplifier for outputting a signal from each PD (hereinafter referred to as a PD signal) to the readout circuit 203, a selection switch for selecting a PD column from which the PD signal is read, and a reset switch for resetting the PD signal. ing. When the pixel 206 is made to function as an imaging pixel, the signals from the two PDs 208 and 209 are added and an imaging signal is output.

  FIG. 3 shows the configuration of the pixel unit 201. In the pixel portion 201, reference numerals 301, 302, 303, and 304 correspond to one pixel 206 shown in FIG. 2B, respectively. Further, 301L, 302L, 303L, and 304L correspond to the PD 208 shown in FIG. 2B, and 301R, 302R, 303R, and 304R correspond to the PD 209 shown in the same figure.

  FIG. 4 shows how a light beam that has passed through the exit pupil 406 of the imaging optical system (not shown) is incident on the imaging sensor 112 having the pixel section 201 configured as described above. Reference numeral 401 denotes the imaging sensor 112, and reference numeral 402 denotes the microlens 207 shown in FIG. 2B. Reference numeral 403 denotes a color filter for transmitting R, G or B light, and reference numerals 404 and 405 denote PDs 208 and 209 shown in FIG. 2B.

  The center of the light flux that has passed through the exit pupil 406 with respect to the pixel having the microlens 402 is referred to as an optical axis 409. The light flux from the exit pupil 406 is incident on the imaging sensor 112 about the optical axis 409. Reference numerals 407 and 408 denote different partial regions in the exit pupil 406 (hereinafter referred to as partial pupil regions). The outermost rays of the light beam passing through the partial pupil area 407 are indicated by 410 and 411. Also, the outermost rays of the light flux passing through the partial pupil area 408 are indicated by 412 and 413. As can be seen from FIG. 4, among the light fluxes from the exit pupil 406, the light fluxes on the upper side sandwiching the optical axis 409 enter the PD 405, and the lower light fluxes enter the PD 404. That is, each of the PD 404 and the PD 405 receives the light flux from the different area in the exit pupil 406 of the imaging optical system.

  Although two PDs 404 and 405 are provided for one microlens in FIG. 2B and FIG. 4, only one PD of the PDs 404 and 405 is provided for one pixel, and the other pixel is provided for the other. Only PD of may be provided. That is, a pair of PDs may be provided to respectively receive the light beams from different partial pupil regions 407 and 408.

  In the imaging sensor 112, a line of PD (hereinafter referred to as A line) for receiving the light flux from the partial pupil area 407 and a line of PD (hereinafter referred to as B line) for receiving the light flux from the partial pupil area 408 Horizontally and vertically aligned. In FIG. 3, among the pixel lines 305, PDs 301L, 302L, 303L, and 304L form an A line extending in the horizontal direction, and 301R, 302R, 303R, and 304R form a B line extending in the horizontal direction. However, in practice, as described above, R, G or B color filters are arranged for each pixel, so the A line and B line are pixels where color filters of the same color are respectively arranged (for example, G color filters It is preferable to form by PD of arrange | positioned G pixel.

  Two images as a pair of subject images (optical image: first subject image) formed on the A and B lines are photoelectrically converted by the PDs of the A and B lines. The PD signals from the A and B lines form two image signals as a pair of first focus detection image signals. The shift amount (phase difference) which is the interval between the two image signals differs depending on the focus state (focus state, front pin state and back pin state) of the imaging optical system with respect to the object, that is, the defocus amount. Therefore, the defocus amount can be calculated by calculating the displacement amount of the two image signals. Then, the amount of movement of the focus lens (focus drive amount) for obtaining the in-focus state is calculated using the amount of defocus and the amount of change in the amount of defocus with respect to the unit movement amount of the focus lens (focus sensitivity). be able to.

  FIG. 5 shows an optical configuration (a part of a lens interchangeable single-lens reflex camera (hereinafter referred to as a camera body) 5100 which is an imaging device having an imaging sensor 112 and an interchangeable lens 5200 detachably mounted on the camera body 5100. Shows the electrical configuration). In the interchangeable lens 5200, an imaging optical system including a focusing lens 5201 is provided.

  In the camera body 5100, a main mirror 5101 is disposed in the imaging light path as shown in the figure in the finder observation state, and is retracted out of the imaging light path in the imaging state. The main mirror 5101 is a half mirror and reflects the light flux from the interchangeable lens (imaging optical system) 5200, that is, a part of the light flux from the subject toward the optical finder described later, when disposed in the imaging light path. Permeate the rest. Reference numeral 5109 denotes a sub mirror, which reflects the light flux transmitted through the main mirror 5101 toward a focus detection unit 5110 provided separately from the imaging sensor 112.

  Reference numeral 5102 denotes a focusing plate which constitutes a part of the optical finder and is disposed on a predetermined imaging surface of the imaging optical system. Reference numeral 5103 denotes a pentaprism for bending the finder optical path. An eyepiece lens 5104 allows the user to visually recognize the subject image by observing the focusing plate 5102 through the eyepiece lens 5104 and the pentaprism 5103.

  Reference numeral 5105 denotes an imaging lens, and reference numeral 5106 denotes a photometric sensor for measuring subject brightness. The imaging lens 5105 focuses a part of the light flux from the focusing plate 5102 that has passed through the pentaprism 5103 on the photometric sensor 5106. Thus, the photometric sensor 5106 can measure the brightness of the subject image on the focusing plate 5102 as the subject brightness.

  A focal plane shutter 5107 controls the exposure of the image sensor 5108. The imaging sensor 5108 is also disposed on the planned imaging surface of the imaging optical system.

  The focus detection unit 5110 splits the light beam incident from the sub mirror 5109 into two by using a dedicated sensor for focus detection (a focus detection sensor) including a plurality of PDs, and two images of these two divided beams on the focus detection sensor. And a secondary imaging lens to be formed. The focus detection unit 5110 sends two image signals obtained by photoelectrically converting the two images by the PD to a camera microcomputer to be described later.

  On the other hand, the interchangeable lens 5200 is provided with an imaging optical system including the above-described focus lens 5201, variable magnification lens 5202, fixed lens 5203, and stop 5204. The focus lens 5201 and the variable magnification lens 5202 move in the optical axis direction of the imaging optical system to perform focus adjustment and variable magnification. The diaphragm 504 adjusts the amount of light incident into the camera body 5100 by increasing or decreasing the diameter of the diaphragm opening.

  An AF driving circuit 5205 drives the focus lens 5201 in the optical axis direction, and includes a focus actuator such as a DC motor or a stepping motor. A zoom driving circuit 5206 drives the variable magnification lens 5202 in the optical axis direction, and includes a zoom actuator such as a DC motor or a stepping motor. An aperture driving circuit 5207 includes an aperture actuator such as a DC motor or a stepping motor. Reference numeral 5208 denotes a mount contact group as a communication interface for enabling communication between the camera body 5100 and the interchangeable lens 5200.

  FIG. 6 shows an electrical configuration (including an optical configuration in part) of the camera body 5100 and the interchangeable lens 5200. The components shown in FIG. 5 are assigned the same reference numerals as those in FIG. The AF drive circuit 5205, the zoom drive circuit 5206, and the diaphragm drive circuit 5207 are controlled by the camera microcomputer 6122 via communication with the interchangeable lens 5200. The shutter drive circuit 6111 is controlled by the camera microcomputer 6122 to drive the focal plane shutter 5107.

  The camera microcomputer 6122 calculates the amount of deviation of the two image signals input from the imaging sensor 112 and the focus detection unit 5110, and calculates the amount of defocus from the amount of deviation. Further, the focus drive amount is calculated using the defocus amount and the above-mentioned focus sensitivity, and the information of the focus drive amount is transmitted to the interchangeable lens 5200. Thus, the AF drive circuit 5205 drives the focus lens 5201 according to the received focus drive amount. Focus detection in the phase difference detection method using the focus detection unit 5110 is referred to as non-imaging surface focus detection, and driving (AF) of the focus lens 5201 based on the result is referred to as non-imaging surface phase difference AF.

  6112 is a clamp circuit and 6113 is an AGC circuit. The clamp circuit 6112 and the AGC circuit 6113 perform basic analog signal processing before A / D conversion. The camera microcomputer 6122 sets the clamp level and the AGC reference level for the clamp circuit 6112 and the AGC circuit 6113 through the video signal processing circuit 6115.

  An A / D converter 6114 converts an analog imaging signal output from the imaging sensor 5108 into a digital imaging signal. A video signal processing circuit 6115 is formed of a logic device such as a gate array. Reference numeral 6116 denotes a TFT drive circuit, and 6117 denotes a TFT (liquid crystal) monitor provided on the back of the camera body 5100. 6118 is a memory controller and 6119 is a memory. An interface 6120 is connectable to an external computer or the like, and 6121 is a buffer memory.

  The video signal processing circuit 6115 performs filter processing, color conversion processing, and gamma processing on the digital imaging signal from the A / D converter 6114 to generate image data. Further, compression processing such as JPEG is performed on image data, and compressed image data is output to the memory controller 6118. The video signal processing circuit 6115 can output the generated image data and the image data input from the memory controller 6118 to the TFT monitor 6117 through the TFT drive circuit 6116. Further, the video signal processing circuit 6115 outputs information such as the exposure of the image sensor 5108 and the white balance to the camera microcomputer 6122 as necessary. The camera microcomputer 6122 controls gain and white balance based on the information.

  The memory controller 6118 stores the unprocessed image data input from the video signal processing circuit 6115 in the buffer memory 6121 and stores the processed image data in the memory 6119. Further, the memory controller 6118 causes the video signal processing circuit unit 6115 to output image data from the buffer memory 6121 or the memory 6119. The memory 6119 may be removable. Furthermore, the memory controller 6118 can also output the image data stored in the memory 6119 via the interface 6120 to an external monitor or the like.

  An operation member 6123 transmits an operation signal corresponding to the user's operation to the camera microcomputer 6122. The camera microcomputer 6122 controls the operation of the camera body 5100 according to the operation signal. 6124 is a switch 1 (hereinafter referred to as SW1), and 6125 is a switch 2 (hereinafter referred to as SW2). The switch SW1 is turned on by a half-press operation of the release button which is 1 of the operation member, and in response to this, the camera microcomputer 6122 performs an AF operation and a photometric operation. The switch SW2 is turned on by the full-pressing operation of the release button, and in response to this, the camera microcomputer 6122 performs an imaging operation. The operation member 6123 includes an ISO setting button, an image size setting button, an image quality setting button, various operation buttons such as an information display button, a switch, a dial, and the like.

  6126 is a liquid crystal drive circuit, and 6127 is an external liquid crystal display element. Reference numeral 6128 denotes a liquid crystal display element in the finder. The liquid crystal drive circuit 6126 drives the external liquid crystal display element 6127 and the in-finder liquid crystal display element 6128 to display a captured image and various information under display control of the camera microcomputer 6122.

  A non-volatile memory (EEPROM) 6129 stores various data. A power supply unit 6130 supplies necessary power to each circuit and drive system.

  Next, the configuration of the focus detection unit 5110 will be described using FIGS. 7 (A) and 7 (B). FIG. 7A shows the focus detection unit 5110 in an exploded manner, and FIG. 7B shows the optical configuration of the focus detection unit 5110. At the left end of FIGS. 7A and 7B, there is a primary imaging plane conjugate with the imaging sensor 112, that is, a planned imaging plane of the imaging optical system. The focus detection unit 5110 includes a field mask 7001, a field lens 7002, a porous stop 7003, a secondary imaging lens unit 7004, and a focus detection sensor 7005 disposed in order from the primary imaging surface side.

  The field mask 7001 is a thin plate-like component having an opening 7001A at the center. The shape of the aperture 7001A defines an image field to be imaged on the focus detection sensor 7005. The field lens 7002 is a convex lens and is provided in the vicinity of the field mask 7001. A field lens 7002 forms an image of the porous stop 7003 in the vicinity of the exit pupil of the imaging optical system. When the size of the exit pupil corresponds to a bright (shallow focal depth) lens for higher accuracy in the area of F5.6, the base length is increased as the area of F2.8.

  The porous diaphragm 7003 is a thin plate-like component having openings 7003A and 7003B at two locations. The openings 7003A and 7003B divide the light beam incident from the field lens 7002 in the horizontal direction. The secondary imaging lens unit 7004 has secondary imaging lenses 7004A and 7004B that are two (a pair of) convex lenses on the surface facing the focus detection sensor 7005. The secondary imaging lenses 7004A and 7004B re-image the object image on the primary imaging surface formed by the imaging optical system on the focus detection sensor 7005. Specifically, the light flux that has passed through the aperture 7003A of the multi-aperture stop 7003 is imaged on the focus detection sensor 7005 by the secondary imaging lens 7004A. The luminous flux having passed through the aperture 7003 B of the multi-aperture stop 7003 is imaged on the focus detection sensor 7005 by the secondary imaging lens 7004 B. As a result, two images (second object images) are formed on the focus detection sensor 7005.

  The focus detection sensor 7005 photoelectrically converts the two images on the light receiving surface and outputs a two image signal as an electric signal. In the focus detection sensor 7005, a plurality of pixels (PDs) are arranged to form two (pair) line sensors 7005A and 7005B. In this embodiment, the line sensors 7005A and 7005B are disposed so as to perform focus detection in the central portion of the range where the object image is formed (OA in FIG. 7B is the optical axis of the imaging optical system). It is done. By photoelectrically converting the two images by each of the pair of line sensors 7005A and 7005B, two image signals as a pair of second focus detection image signals are generated.

  Here, the factors of the focus detection error generated in the focus detection unit 5110 shown in FIGS. 7A and 7B will be described using FIGS. 8A to 8D. FIG. 8A shows a state in which the fields 8001A and 8001B of the pair of line sensors 7005A and 7005B of the focus detection sensor 7005 are ideally back-projected with respect to the subject 8000 having an oblique white line on a black background. . In this ideal state, the fields of view 8001A and 8001B of the pair of line sensors 7005A and 7005B overlap each other. That is, completely the same subject image is formed as two images on the pair of line sensors 7005A and 7005B. Therefore, as shown in FIG. 8B, the outputs 8002A and 8002B of the pair of line sensors 7005A and 7005B have waveforms of the same shape at the same position as each other, which makes it possible to detect the amount of deviation between the two image signals correctly. It becomes possible.

  On the other hand, FIG. 8C shows a state in which the fields of view 8001A and 8001B of the pair of line sensors 7005A and 7005B are back-projected with being vertically shifted with respect to a subject 8000 having an oblique white line on a black background. This state is referred to as so-called “eyebrow” (oblique view), and is generated due to a positional deviation of the field lens 7002, the aperture stop 7003, the secondary imaging lens unit 7004, and the focus detection sensor 7005. In the state where this "gaze" occurs, the fields of view 8001A and 8001B are at the same position in the horizontal direction but do not overlap at all in the vertical direction. Therefore, as shown in FIG. 8D, the waveforms of the outputs 8002A and 8002B of the pair of line sensors 7005A and 7005B shift in the horizontal direction. As a result, the amount of deviation between the two image signals can not be detected correctly, resulting in a focus detection error. As a result, high precision AF can not be performed. Although “Yaburunami” in which the fields of view of the pair of line sensors shift in the vertical direction has been described here, the shift in the field of view due to “Yaburunami” is not limited to the vertical direction.

  It is possible to suppress the above "Yaburunari" without causing any practical problems by adjusting the positional relationship between the field lens 7002, the aperture stop 7003, the secondary imaging lens unit 7004, and the focus detection sensor 7005. It is. However, the focus detection unit 5110 needs to be provided with an adjustment mechanism for adjusting the above-mentioned positional relationship, and the adjustment process takes a long time. On the other hand, if it is determined whether or not a focus detection error may occur due to "viewing", and if the handling of the focus detection result is different according to the determination result, it is possible to suppress the decrease in AF accuracy. Moreover, the adjustment accuracy of the said positional relationship can also be relieved.

  The timing of focus detection using the imaging sensor 112 and focus detection using the focus detection unit 5110 will be described with reference to FIG. In FIG. 9, “M-Up” indicates a state in which the main mirror 5101 is retracted out of the imaging optical path, the focal plane shutter 5107 is opened, and imaging surface focus detection and imaging by the imaging sensor 112 are possible. On the other hand, “M-Down” is a finder observation state in which the main mirror 5101 is disposed in the imaging light path, and indicates a state in which non-imaging surface focus detection by the focus detection unit 5110 is possible. In addition, x1 to x9 indicate changes in the image plane position when the subject (moving object) approaches toward the camera during three consecutive imagings from time t2. Between three imagings, imaging surface focus detection and non-imaging surface focus detection are alternately performed. Non-imaging-plane focus detection is performed at odd times t1, t3, t5, and t7, and imaging-plane focus detection is performed at even times t2, t4, and t6. Ideally, the focal point detection results (defocus amounts) by non-imaging surface focal point detection at time t1, t3, t5 and t7 and imaging surface focal point detection at time t2, t4 and t6 are respectively the image plane positions x1 to x9. Match

  In the following, as shown in FIG. 9, the handling of the focus detection result by non-imaging surface focus detection and imaging surface focus detection which is alternately performed while the image surface position changes in continuous imaging of a moving object will be described.

  First, a method of determining the presence or absence of a focus detection error due to “Yabubira” will be described. In FIG. 10, the pixels of the image sensor 112 (R, G, B surrounded by thin line frames) and the pixels of the line sensor in the focus detection unit 5110 (thick line frames) are drawn overlappingly to compare their sizes. There is. The focus detection unit 5110 emphasizes the low luminance detection performance with respect to the imaging sensor 112 in which the number of pixels is increased. Therefore, the size of one pixel of the focus detection unit 5110 is considerably larger than the size of one pixel of the imaging sensor 112.

  In FIG. 10, reference numeral 10001 denotes a pixel area where focus detection is performed in the imaging sensor 112, and reference numerals 10002 to 10000 denote first to n-th signal readout rows in the pixel area 10001. Each signal readout row includes four pixels in the vertical direction. PD signals read out from G pixels of each signal readout row are added in the vertical direction and used as an output signal (two image signals) of the signal readout row. Then, the correlation of each pair of two image signals of n pairs obtained from each of the first to n-th signal readout rows is calculated, and these n pieces of correlation calculation results are finally added to obtain one correlation. The shift amount (phase difference) of the two image signals as the calculation result is obtained.

  Two image signals for obtaining each correlation calculation result in the imaging sensor 112 are signals obtained from two PDs that receive a light beam divided by a micro lens in the same pixel as described with reference to FIGS. 2 and 3. Because of that, "Yabu ni Remi" does not occur.

  On the other hand, 10006 indicates the range of one line sensor of the focus detection unit 5110, and 10007 to 10012 indicate the first to n-th pixels in the line sensor. A row of pixel signals (PD signals) obtained from the line sensor is one of the two image signals. In the present embodiment, the difference between two image signals obtained from a pair of line sensors is used to determine the presence or absence of a focus detection error due to “frightened eyes”, ie, the reliability of the focus detection result.

  FIGS. 11A and 11B show an image sensor 112 for an object having an oblique white line on the black background shown in FIG. 8 (ie, the same object as the object shown in FIGS. 8A and 8C). 2 shows two image signals obtained from. FIG. 11A shows a pixel region including n signal readout rows 10002 to 1005 for obtaining the correlation calculation result, and FIG. 11B shows each of the first to nth signal readout rows 10002 to 1005. The waveform of the focus detection image signal 11002-11005 obtained is shown. It can be understood from FIG. 11B that the peak positions of the focus detection image signals 11002 to 11005 obtained from the signal readout rows 10002 to 1005 with respect to the subject 8000 are mutually shifted in the horizontal direction.

  In the present embodiment, the focus detection error due to “Yaburairai” described with reference to FIGS. 8C and 8D using the shift of the peak position of this focus detection image signal is used for the subject (two image signals). Determine if there is a possibility of causing it. As shown in FIG. 11B, if the peak positions of the focus detection image signals 11002 to 11005 obtained from each of the signal readout rows 10002 to 1005 are shifted from each other, there is a possibility that a focus detection error due to “viewing” occurs. It can be determined that there is That is, it can be determined that the reliability of the focus detection result obtained by non-imaging surface focus detection using the focus detection unit 5110 is low.

  FIG. 1 shows an AF process executed by a camera microcomputer (hereinafter referred to as a camera microcomputer) 6122. In this AF process, the camera microcomputer 6122 determines the reliability of the focus detection result regarding “Yabu Shirasu”, and according to the determination result, whether to use only imaging surface focus detection for AF or non imaging surface focus detection and imaging surface Select whether to use both of focus detection. The camera microcomputer 6122 executes this process in accordance with a focus control program as a computer program.

  In step S1001, the camera microcomputer 6122 compares the focus detection image signals 11002 to 11005 acquired from each of the signal readout rows 10002 to 1005 of the imaging sensor 112 as shown in FIG. 11B. Then, in step S1002, it is determined whether the peak positions of the focus detection image signals 11002 to 11005 are shifted from each other. That is, it is determined whether or not there is a possibility that a focus detection error may occur due to the subject being "focused upon" in the focus detection unit 5110. The camera microcomputer 6122 proceeds to step S1003 if there is a possibility that a focus detection error due to “restraint on Yabun” occurs, and proceeds to step S1004 if there is no possibility (the peak position is not shifted).

  In step S1003, the camera microcomputer 6122 selects to use only the imaging surface focus detection for AF. Then, in step S1005, the camera microcomputer 6122 calculates the defocus amount by imaging surface focus detection, and drives the focus lens 5201 based on the defocus amount.

  On the other hand, in step S1004, the camera microcomputer 6122 selects using both non-imaging surface focus detection and imaging surface focus detection for AF. Then, in step S1005, the camera microcomputer 6122 calculates the defocus amount by non-imaging surface focus detection, and drives the focus lens 5201 based on the defocus amount. After that, the camera microcomputer 6122 calculates the defocus amount by imaging surface focus detection, and drives the focus lens 5201 based on the defocus amount. As a result, more accurate AF is performed by using both non-imaging surface focus detection and imaging surface focus detection.

  As described above, in the present embodiment, using the focus detection image signal obtained from the imaging sensor 112, the focus detection unit 5110 determines the presence or absence of the possibility of the occurrence of a focus detection error due to "blurring". Then, when there is a possibility of the occurrence of a focus detection error, by using only the focus detection result obtained from the imaging sensor 112 for AF, a good AF is performed in which the decrease in the AF accuracy due to the "eye wear" is suppressed. be able to.

  Next, a second embodiment of the present invention will be described. FIG. 12 shows an optical configuration (a part of which includes an electrical configuration) of a camera body 12100 which is an imaging device having an imaging sensor 112, and an interchangeable lens 5200 removably mounted on the camera body 12100. FIG. 13 shows an electrical configuration (including an optical configuration in part) of the camera body 12100 and the interchangeable lens 5200.

  In the first embodiment described above, the camera body 5100 having the main mirror 5101 which can be advanced and retracted with respect to the imaging optical path has been described. On the other hand, in the second embodiment, the camera body 12100 in which the mirror 12101 is fixed in the imaging light path will be described. In the present embodiment, a light flux incident from an interchangeable lens (imaging optical system) 5200 and reflected by a mirror 12101 is guided to a focus detection unit 12110. In FIG. 12 and FIG. 13, the same components as in the first embodiment are given the same reference numerals as the first embodiment, and the description thereof is omitted.

  As described above, the mirror 12101 is fixed in the imaging light path, reflects a part (for example, half) of the light flux incident from the interchangeable lens 5200 toward the focus detection unit 12110, and the remaining light flux is the imaging sensor 112 Make it transparent to

  The focus detection unit 12110 is configured in the same manner as the focus detection unit 5110 described with reference to FIG. 7 in the first embodiment, and the two image signals for performing focus detection of the imaging optical system by the phase difference detection method are Send to computer 6122 An EVF monitor 12103 constitutes an electronic finder instead of the optical finder provided in the camera body 5100 of the first embodiment. The EVF monitor 12103 is driven by the TFT drive circuit 6116 as with the TFT monitor 6117 provided on the back of the camera body 12100.

  The AF processing executed by the camera microcomputer 6122 in the present embodiment is basically the same as that in the first embodiment. That is, the camera microcomputer 6122 determines the reliability of the focus detection result regarding “Yabu Shirai”, and according to the determination result, whether to use only imaging surface focus detection for AF, non imaging surface focus detection and imaging surface focus detection Choose to use both. Here, while the first embodiment uses the focus detection result obtained by non-imaging surface focus detection and imaging surface focus detection alternately performed during continuous imaging as shown in FIG. The focus detection result obtained by non-imaging surface focus detection and imaging surface focus detection can be used. In the present embodiment, the light flux that has passed through the photographing optical system always enters the imaging sensor 112 and the focus detection unit 5110. As described above, since the pair timing to obtain the result of the imaging surface focus detection based on the output of the imaging sensor 112 does not depend on the driving timing of the main mirror 5101, the continuous imaging is performed not only during the continuous imaging with the servo AF operation. Even when there is no servo AF operation or one-shot AF operation, it is possible to determine the reliability. That is, compared to the case of the first embodiment, it is also possible to monitor, for example, the influence of "regard to the hair" at shorter time intervals. Thereby, it is possible to further reduce the influence of “Yamibari” as compared to, for example, the case of the first embodiment. Further, in the present embodiment, since it is possible to further reduce the influence of “Yaburinami” as compared with the first embodiment, the focus detection unit 12110 has a larger degree of “Yaburanami” than the case of the first embodiment. Can also be used. Accordingly, it is possible to simplify the adjustment of the positional relationship of each part of the focus detection unit 12110 as compared with the case of the first embodiment. This can reduce the production cost.

As described above, also in the present embodiment, the focus detection unit 5110 determines the possibility of the occurrence of a focus detection error due to “blurring” using the focus detection image signal obtained from the imaging sensor 112. Then, when there is a possibility of the occurrence of a focus detection error, by using only the focus detection result obtained from the imaging sensor 112 for AF, a good AF is performed in which the decrease in the AF accuracy due to the "eye wear" is suppressed. be able to.
(Other embodiments)
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. Can also be realized. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.

  The embodiments described above are only representative examples, and various modifications and changes can be made to the embodiments when the present invention is implemented.

112 Image sensor 5100, 12100 Camera body 5110 Focus detection unit 5200 Shooting lens 6122 Camera microcomputer

Claims (6)

The photoelectric conversion of the first subject image of the pair obtained by dividing the light flux from the imaging optical system to generate the first focus detection image signal of the pair, and the imaging for picking up the subject image formed by the light flux Sensor,
And a focus detection unit provided separately from the image sensor and photoelectrically converting a second object image of a pair obtained by dividing a light beam from the image pickup optical system to generate a second focus detection image signal of the pair ,
Control means for performing focus control of the imaging optical system using at least one of the first and second focus detection image signals;
The control means determines the reliability of the second focus detection image signal according to the result of comparing the plurality of first focus detection image signals acquired from a plurality of regions in the imaging sensor, and the determination result An imaging apparatus characterized in that focus control is performed based on.   The control means compares peak positions of the plurality of first focus detection image signals, and when the result that there is a shift in the peak positions is obtained, the reliability of the second focus detection image signal is obtained. 2. The image pickup apparatus according to claim 1, wherein it is determined that the second focus detection image signal is not used for the focus control by determining that the second focus detection image signal is low.   The imaging apparatus according to claim 1, wherein the first subject image and the second subject image are optical images of the same subject. The control means
When it is selected that the second focus detection image signal is not used for the focus control, the focus control is performed using the pair of first focus detection image signals,
When it is selected to use the second focus detection image signal for the focus control, the focus control is performed using the first focus detection image signal of the pair and the second focus detection image signal of the pair. The imaging device according to any one of claims 1 to 3, characterized by The photoelectric conversion of the first subject image of the pair obtained by dividing the light flux from the imaging optical system to generate the first focus detection image signal of the pair, and the imaging for picking up the subject image formed by the light flux A sensor and a focus sensor which is separately provided from the image sensor and photoelectrically converts a pair of second object images obtained by dividing a light flux from the image pickup optical system to generate a pair of second focus detection image signals A control method for causing an imaging apparatus having a detection unit to perform focus control of the imaging optical system using at least one of the first and second focus detection image signals.
Acquiring a plurality of first focus detection image signals from a plurality of areas in the imaging sensor;
Determining the reliability of the second focus detection image signal according to the result of comparing the plurality of first focus detection image signals, and performing focus control based on the determination result Control method of the imaging device. The photoelectric conversion of the first subject image of the pair obtained by dividing the light flux from the imaging optical system to generate the first focus detection image signal of the pair, and the imaging for picking up the subject image formed by the light flux A sensor and a focus sensor which is separately provided from the image sensor and photoelectrically converts a pair of second object images obtained by dividing a light flux from the image pickup optical system to generate a pair of second focus detection image signals A computer program that causes a computer of an imaging apparatus having a detection unit to perform focus control of the imaging optical system using at least one of the first and second focus detection image signals,
On the computer
A process of acquiring a plurality of first focus detection image signals from a plurality of areas in the imaging sensor;
It is characterized in that the reliability of the second focus detection image signal is determined according to the result of comparison of the plurality of first focus detection image signals, and processing for performing focus control is performed based on the determination result. Focus control program.