JP2019091090A - Detector, imaging element, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection device capable of appropriately detecting the focus of an optical system. SOLUTION: A detection unit composed of a plurality of focusing detection pixels arranged in a first direction is provided in a second direction intersecting the first direction, and an image formed by an optical system is imaged and a signal is output. The position of the image by the optical system and the amount of deviation between the image sensor and the image sensor are calculated by using the first signal output from the detection unit according to the signal from the detection unit and the image sensor. A detection device having a calculation unit that performs either a first calculation and a second calculation that calculates the deviation amount using a second signal output from the plurality of detection units. [Selection diagram] FIG. 5

Description

  The present invention relates to a detection device, an imaging device, and an imaging device.

  2. Description of the Related Art Conventionally, an imaging element having an imaging pixel for imaging and a focus detection pixel for performing focus detection by a phase difference detection method has been known (see, for example, Patent Document 1). However, in the technique of Patent Document 1, the first focus detection pixel for receiving one of the pupil-divided light flux and the second focus detection pixel for receiving the other pupil-divided light flux in the lateral direction Since the output from the first focus detection pixel and the output from the second focus detection pixel are offset by 0.5 pixels, the output of the optical system is In some cases, focus detection can not be performed with high accuracy.

JP 2012-226088 A

  The problem to be solved by the present invention is to provide a detection device, an imaging device, and an imaging device capable of appropriately performing focus detection of an optical system.

  The present invention solves the above-mentioned subject by the following solution means.

[1] A detection device according to the present invention includes a plurality of detection units including a plurality of focus detection pixels arranged in a first direction in a second direction intersecting the first direction, and an image formed by an optical system An imaging device for capturing an image and outputting a signal, and a first detection unit outputting a shift amount between the position of the image by the optical system and the imaging device according to a signal from one of the detection units. And a calculation unit that performs one of a first calculation using a signal and a second calculation using the second signal output from the plurality of detection units.
[2] In the invention according to the above detection apparatus, the calculation unit is configured to perform either the first calculation or the second calculation according to any one of the magnitude and the contrast of the first signal. can do.
[3] In the invention according to the above detection apparatus, the magnitude of the first signal when performing the first calculation can be configured to be larger than the magnitude of the first signal when performing the second calculation.
[4] In the invention according to the above detection apparatus, the contrast value of the first signal when the first calculation is performed by the calculation unit is higher than the contrast value of the first signal when the second calculation is performed. Can be configured to
[5] In the invention according to the above detection device, the second signal can be configured to be a signal obtained by adding the signals output from a plurality of the detection units.
[6] In the invention according to the above detection apparatus, the second calculation performed by the calculation unit calculates the amount of deviation using the second signal according to the second signal, and the second signal is used as the second signal. The deviation amount may be calculated by using a third signal obtained by adding the signal output from the detection unit.
[7] In the invention according to the above detection apparatus, the calculation unit calculates the amount of deviation using the second signal according to one of the magnitude of the second signal and the contrast of the output signal. One of the calculation of the amount of deviation using the third signal can be performed.
[8] In the invention according to the above detection apparatus, the detection section of the image pickup device includes a first pixel for receiving light passing through a first region of the optical system, and the first of the optical system. The second pixels that receive the light that has passed through the second region different from the region may be alternately arranged in the first direction.
[9] In the invention according to the above-mentioned detection device, the first and second pixels may be alternately arranged in the second direction in the imaging device.
[10] In the invention according to the detection device, the second calculation performed by the calculation unit may be the number of first pixels and the number of second pixels in the second direction of the detection unit used in the second calculation. The shift amount can be calculated using a signal obtained by multiplying the signal output from the detection unit used in the second operation after the coefficient determined in accordance with the ratio of .beta.
[11] The detection device according to the present invention is different from a plurality of first pixels for receiving light passing through a first area of an optical system for forming an image of a subject and the first area of the optical system An imaging element having a plurality of second pixels for receiving light passing through the second region, and a first signal output from a first pixel row consisting of a plurality of first pixels arranged in a first direction; An image by the optical system from the first signal and the second signal according to a signal of a second signal output from a second pixel row composed of a plurality of second pixels arranged in the first direction A first operation for calculating a value relating to the amount of deviation between the position of the imaging element and the imaging surface of the imaging element, and the second direction intersecting the first direction is disposed at a position different from the first pixel row; A third signal generated in a third pixel row consisting of a plurality of first pixels arranged in the And the fourth signal front generated by the fourth pixel row composed of the plurality of second pixels arranged at positions different from the second pixel row in the first direction. And a calculator configured to perform one of a second operation of calculating a value related to the amount of deviation from a fifth signal and a sixth signal generated by adding the signal and the second signal.
[12] An imaging device according to the present invention includes the above detection device.
[13] The imaging device according to the present invention is different from a plurality of first pixels for receiving light passing through a first area of an optical system for forming an image of a subject and the first area of the optical system A first signal generated in a first pixel row comprising a plurality of second pixels that receive light passing through the second region and a plurality of the first pixels arranged in the first direction, in the first direction A second signal generated by a second pixel row composed of the plurality of second pixels disposed, the second signal being disposed at a position different from the first pixel row in a second direction intersecting the first direction, the first direction A third signal generated by a third pixel row consisting of a plurality of first pixels arranged in a plurality of the plurality of pixels arranged at positions different from the second pixel row in the second direction and arranged in the first direction A fourth signal generated in a fourth pixel column comprising the second pixels, and a plurality of signals constituting the first signal A fifth signal generated by adding a plurality of signals forming the third signal in the second direction, a plurality of signals forming the second signal, and a plurality of signals forming the fourth signal And an output unit that outputs a sixth signal generated by adding in the second direction.
[14] An imaging device according to the present invention includes the imaging element.

  According to the present invention, it is possible to provide an imaging device capable of appropriately performing focus detection of an optical system, and an imaging device provided with the imaging device.

FIG. 1 is a block diagram showing a camera according to the present embodiment. FIG. 2 is a front view showing an imaging surface of the imaging device shown in FIG. FIG. 3 is a front view schematically showing an arrangement of the imaging pixel 221 and the focus detection pixels 222a and 222b by enlarging the part III of FIG. 4A is an enlarged front view showing one of the imaging pixels 221, FIG. 4B is an enlarged front view showing one of the first focus detection pixels 222a, and FIG. 4C. 4A is a front view showing an enlarged view of one of the second focus detection pixels 222b, FIG. 4D is a sectional view showing an enlarged view of one of the imaging pixels 221, and FIG. 4E shows a first focus FIG. 4F is a cross-sectional view showing one of the second focus detection pixels 222b in an enlarged manner. FIG. 5 is a view schematically showing the arrangement of the focus detection pixels 222a and 222b. 6 is a cross-sectional view taken along the line VI-VI in FIG. FIG. 7 is a graph showing the relationship between the correlation amount and the shift amount in the present embodiment. FIG. 8 is a graph showing the relationship between the correlation amount and the shift amount in the prior art. FIG. 9 is a flowchart showing the operation of the camera according to the first embodiment. FIG. 10 is a front view schematically showing a configuration of an imaging device 22a according to the second embodiment. FIG. 11 is a diagram schematically showing the arrangement of the focus detection pixels 222a and 222b. FIG. 12 is a flowchart showing the operation of the camera according to the second embodiment. FIG. 13 is a flowchart showing the operation of the camera according to the third embodiment. FIG. 14 is a front view schematically showing the configuration of an imaging device 22a according to the fourth embodiment. FIG. 15 is a diagram schematically showing the arrangement of the focus detection pixels 222a and 222b. FIG. 16 is a flowchart showing the operation of the camera according to the fourth embodiment. FIG. 17 is a flowchart showing the operation of the camera according to the fifth embodiment. FIG. 18 is a front view schematically showing a configuration of an imaging device 22c according to another embodiment. FIG. 19 is a front view schematically showing a configuration of an imaging device 22d according to still another embodiment. FIG. 20 is a front view schematically showing a configuration of an imaging device 22e according to still another embodiment.

  Hereinafter, embodiments of the present invention will be described based on the drawings.

First Embodiment
FIG. 1 is a main part configuration diagram showing a digital camera 1 according to an embodiment of the present invention. The digital camera 1 (hereinafter simply referred to as the camera 1) of the present embodiment is composed of a camera body 2 and a lens barrel 3, and the camera body 2 and the lens barrel 3 are detachably coupled by a mount unit 4 There is.

  The lens barrel 3 is an interchangeable lens that is detachable from the camera body 2. As shown in FIG. 1, the lens barrel 3 incorporates a photographing optical system including lenses 31, 32, 33 and a diaphragm 34.

  The lens 32 is a focus lens, and can move in the direction of the optical axis L1 to adjust the focus state of the photographing optical system. The focus lens 32 is provided so as to be movable along the optical axis L1 of the lens barrel 3, and its position is adjusted by the focus lens drive motor 36 while its position is detected by the encoder 35.

  The aperture 34 is configured to adjust the aperture diameter centered on the optical axis L1 in order to limit the light amount of the light flux passing through the imaging optical system and reaching the imaging device 22 and to adjust the blur amount. Adjustment of the aperture diameter by the aperture stop 34 is performed, for example, by transmitting an appropriate aperture diameter calculated in the automatic exposure mode from the camera control unit 21 via the lens control unit 37. Further, the set aperture diameter is input from the camera control unit 21 to the lens control unit 37 by the manual operation by the operation unit 28 provided in the camera body 2. The aperture diameter of the diaphragm 34 is detected by a diaphragm aperture sensor (not shown), and the lens controller 37 recognizes the current aperture diameter.

  The lens control unit 37 controls the entire lens barrel 3 such as driving of the focus lens 32 and adjustment of the aperture diameter by the diaphragm 34 based on a command from the camera control unit 21.

  On the other hand, in the camera body 2, an imaging element 22 for receiving the light flux L1 from the imaging optical system is provided on a planned focal plane of the imaging optical system, and a shutter 23 is provided on the front surface thereof. The imaging device 22 is configured of a device such as a CCD or a CMOS, converts the received light signal into an electric signal, and sends it to the camera control unit 21. The photographed image information sent to the camera control unit 21 is sequentially sent to the liquid crystal drive circuit 25 and displayed on the electronic viewfinder (EVF) 26 of the observation optical system, and the release button (provided in the operation unit 28) When the full depression (not shown) is performed, the photographed image information is recorded in the camera memory 24 which is a recording medium. The camera memory 24 can use any of a removable card type memory and a built-in type memory. Details of the structure of the imaging device 22 will be described later.

  The camera body 2 is provided with an observation optical system for observing an image captured by the image sensor 22. The observation optical system of the present embodiment includes an electronic viewfinder (EVF) 26 composed of a liquid crystal display element, a liquid crystal drive circuit 25 for driving the same, and an eyepiece lens 27. The liquid crystal drive circuit 25 reads the photographed image information picked up by the image pickup device 22 and sent to the camera control unit 21, and drives the electronic viewfinder 26 based on this. Thus, the user can observe the current captured image through the eyepiece 27. A liquid crystal display may be provided on the back surface of the camera body 2 or the like instead of or in addition to the above observation optical system according to the optical axis L2, and a photographed image may be displayed on the liquid crystal display.

  A camera control unit 21 is provided in the camera body 2. The camera control unit 21 receives various lens information and transmits information such as the defocus amount and the aperture diameter to the lens control unit 37. In addition, as described above, the camera control unit 21 reads out the pixel output from the imaging device 22 and generates image information by performing predetermined information processing on the read out pixel output as necessary, and the generated image information Are output to the liquid crystal drive circuit 25 and the memory 24 of the electronic viewfinder 26. Further, the camera control unit 21 controls the entire camera 1 such as correction of image information from the image pickup device 22 and detection of a focusing state of the lens barrel 3, an aperture adjusting state, and the like.

  Further, in addition to the above, the camera control unit 21 detects the focus state of the photographing optical system by the phase detection method based on the pixel data read from the imaging device 22 and detects the focus state of the photographing optical system by the contrast detection method. I do. A specific focus state detection method will be described later.

  The operation unit 28 is an input switch for a photographer such as a shutter release button to set various operation modes of the camera 1, and can switch between an auto focus mode and a manual focus mode. The various modes set by the operation unit 28 are sent to the camera control unit 21, and the operation of the entire camera 1 is controlled by the camera control unit 21. Further, the shutter release button includes a first switch SW1 which is turned on when the button is half pressed, and a second switch SW2 which is turned on when the button is fully pressed.

  Next, the image sensor 22 according to the present embodiment will be described.

  2 is a front view showing the imaging surface of the imaging element 22, and FIG. 3 is a front view schematically showing the arrangement of the imaging pixel 221 and the focus detection pixels 222a and 222b by enlarging the portion III of FIG.

  As shown in FIG. 3, in the imaging device 22 of the present embodiment, a plurality of imaging pixels 221 are two-dimensionally arranged on a plane of an imaging surface, and a green pixel G having a color filter transmitting a green wavelength region And a red pixel R having a color filter transmitting the red wavelength region and a blue pixel B having a color filter transmitting the blue wavelength region are what is called a Bayer arrangement. That is, two green pixels are arranged on one diagonal line in adjacent four pixel groups 223 (a dense square lattice array), and one red pixel and one blue pixel are arranged on the other diagonal line. The imaging element 22 is configured by repeatedly arranging the pixel group 223 two-dimensionally on the imaging surface of the imaging element 22 in units of the pixel group 223 in which the Bayer arrangement is performed. In the present embodiment, one pixel is formed by the four pixel groups 223.

  The arrangement of the unit pixel groups 223 may be, for example, a close hexagonal lattice arrangement, as well as the close square lattice shown in the drawing. Further, the configuration and arrangement of the color filter are not limited to this, and an arrangement of complementary color filters (green: G, yellow: Ye, magenta: Mg, cyan: Cy) can also be adopted.

  FIG. 4A is an enlarged front view showing one of the imaging pixels 221, and FIG. 4D is a cross-sectional view. One imaging pixel 221 includes a microlens 2211, a photoelectric conversion unit 2212, and a color filter (not shown), and as shown in the cross-sectional view of FIG. 4D, on the surface of the semiconductor circuit substrate 2213 of the imaging element 22. The photoelectric conversion portion 2212 is fabricated, and the micro lens 2211 is formed on the surface thereof. The photoelectric conversion unit 2212 is shaped so as to receive the imaging light flux passing through the exit pupil (for example, F1.0) of the photographing optical system 31 by the microlens 2211 and receives the imaging light flux.

  In addition, focus detection pixel column groups 22a and 22b, in which focus detection pixels 222a and 222b are arranged instead of the above-described imaging pixels 221 at the center of the imaging surface of the imaging element 22 and at three positions symmetrical with respect to the center. 22c is provided. Then, as shown in FIG. 3, one focus detection pixel column group includes two focus detection pixel columns, that is, a first focus detection pixel column L1 and a second focus detection pixel column L2, and each focus detection pixel The columns L1 and L2 are configured such that a plurality of first focus detection pixels 222a and second focus detection pixels 222b are alternately arranged adjacent to each other in a horizontal row. In the present embodiment, as shown in FIG. 3, the first focus detection pixel 222 a and the second focus detection pixel 222 b provide gaps at the positions of the green pixel G and the blue pixel B of the imaging pixel 221 in Bayer arrangement. It is densely arranged without.

  Note that the positions of the focus detection pixel column groups 22a to 22c shown in FIG. 2 are not limited to the positions shown in the drawing, and may be one or two, or may be arranged at four or more positions. You can also Further, upon actual focus detection, the user selects a desired focus detection pixel row as a focus detection position by manually operating the operation unit 28 from the plurality of arranged focus detection pixel row groups 22a to 22c. It can also be done.

  FIG. 4B is an enlarged front view showing one of the first focus detection pixels 222a, and FIG. 4E is a cross-sectional view of the first focus detection pixel 222a. 4C is an enlarged front view showing one of the second focus detection pixels 222b, and FIG. 4F is a cross-sectional view of the second focus detection pixel 222b. The first focus detection pixel 222a includes a micro lens 2221a and a rectangular photoelectric conversion unit 2222a as shown in FIG. 4B, and as shown in the cross sectional view of FIG. A photoelectric conversion portion 2222a is formed on the surface of the twenty-two semiconductor circuit substrates 2213, and a micro lens 2221a is formed on the surface. The second focus detection pixel 222b is composed of a micro lens 2221b and a photoelectric conversion unit 2222b as shown in FIG. 4C, and as shown in the cross sectional view of FIG. The photoelectric conversion portion 2222 b is formed on the surface of the semiconductor circuit substrate 2213, and the micro lens 2221 b is formed on the surface. Then, as shown in FIG. 3, the focus detection pixels 222a and 222b are arranged adjacent to each other and alternately in a horizontal row, thereby constituting the respective focus detection pixel rows L1 and L2.

  The photoelectric conversion units 2222a and 2222b of the first focus detection pixel 222a and the second focus detection pixel 222b are luminous fluxes passing through a predetermined area (for example, F2.8) of the exit pupil of the photographing optical system by the micro lenses 2221a and 2221b. Is shaped to receive light. Further, no color filter is provided in the first focus detection pixel 222a and the second focus detection pixel 222b, and the spectral characteristics are the spectral characteristics of a photodiode that performs photoelectric conversion and the spectral characteristics of an infrared cut filter (not shown). It has become a synthesis of the characteristics. However, one of the same color filters as the imaging pixel 221, for example, a green filter may be provided.

  Although the photoelectric conversion units 2222a and 2222b of the first focus detection pixel 222a and the second focus detection pixel 222b shown in FIGS. 4B and 4C are rectangular, the shapes of the photoelectric conversion units 2222a and 2222b are shown. Is not limited to this, and may be another shape, for example, a semicircular shape, an elliptical shape, or a polygonal shape.

  Returning to FIG. 3, as described above, the imaging device 22 of the present embodiment includes the two focus detection pixel arrays L1 and L2. Here, FIG. 5 excludes the imaging pixel 221 from the imaging surface of the imaging device 22 shown in FIG. 3, and only the first focus detection pixel 222a and the second focus detection pixel 222b that constitute two focus detection pixel rows L1 and L2 Are schematically shown. As shown in FIG. 5, of the two focus detection pixel lines L1 and L2, the first focus detection pixel line L1 is a first focus detection pixel 222a and a second focus detection along the X-axis direction (row direction). The pixels 222 b are alternately arranged in the order of the first focus detection pixels 222 a and the second focus detection pixels 222 b. On the other hand, the second focus detection pixel row L2 is configured by alternately arranging the first focus detection pixels 222a and the second focus detection pixels 222b, similarly to the first focus detection pixel row L1. Although the arrangement order of the first focus detection pixels 222a and the second focus detection pixels 222b is different from that of the first focus detection pixel row L1, the arrangement order is different.

  That is, as shown in FIG. 5, when viewed in the X-axis direction (row direction), in the first focus detection pixel column L1, the second focus detection pixel is located where the first focus detection pixel 222a is located. In the column L2, the second focus detection pixel 222b is positioned, and in the first focus detection pixel column L1, the first focus detection pixel 222a is positioned where the second focus detection pixel 222b is positioned. It is configured as

  Next, a so-called phase difference detection method will be described in which the focus state of the photographing optical system is detected based on the pixel outputs of the focus detection pixels 222a and 222b described above.

  FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 3 and is disposed in the vicinity of the photographing optical axis L1 and the focus detection pixels 222a-1, 222b-1, 222a-2, 222b-2 adjacent to each other are It shows that light beams AB1-1, AB2-1, AB1-2, and AB2-2 emitted from the focusing pupils 351 and 352 of the exit pupil 350 are respectively received. Although FIG. 6 illustrates only one of the plurality of focus detection pixels 222a and 222b located in the vicinity of the photographing optical axis L1, the other focus detection pixels other than the focus detection pixels shown in FIG. 6 are shown. Similarly, the light beams emitted from the pair of distance measuring pupils 351 and 352 are also received.

  Here, the exit pupil 350 is an image set at the position of the distance D in front of the microlenses 2221 a and 2221 b of the focus detection pixels 222 a and 222 b disposed on the planned focal plane of the imaging optical system. The distance D is a value uniquely determined according to the curvature of the micro lens, the refractive index, the distance between the micro lens and the photoelectric conversion part, and the like, and this distance D is referred to as a distance measurement pupil distance. Further, the ranging pupils 351 and 352 refer to images of the photoelectric conversion units 2222a and 2222b respectively projected by the micro lenses 2221a and 2221b of the focus detection pixels 222a and 222b.

  In FIG. 6, the arrangement direction of the focus detection pixels 222 a-1, 222 b-1, 222 a-2 and 222 b-2 coincides with the arrangement direction of the pair of distance measurement pupils 351 and 352.

  Further, as shown in FIG. 6, the microlenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 of the focus detection pixels 222a-1, 222b-1, 222a-2, 222b-2 are photographing optical systems. It is placed near the planned focal plane of. The shape of each of the photoelectric conversion units 2222a-1, 2222b-1, 2222a-2, 2222b-2 disposed behind the microlenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 is The light is projected onto the exit pupil 350 separated by the distance measurement distance D from the lenses 2221a-1 and 2221b-1, and 2221a-2 and 2221b-2, and the projected shapes form distance measurement pupils 351 and 352.

  That is, on the exit pupil 350 located at the distance measurement distance D, the microlenses and photoelectric conversion units in each focus detection pixel are matched so that the projection shapes (distance measurement pupils 351, 352) of the photoelectric conversion units of each focus detection pixel match. The relative positional relationship of is determined, whereby the projection direction of the photoelectric conversion unit at each focus detection pixel is determined.

  As shown in FIG. 6, the photoelectric conversion unit 2222a-1 of the focus detection pixel 222a-1 is formed on the microlens 2221a-1 by the light beam AB1-1 which passes through the distance measurement pupil 351 and is directed to the microlens 2221a-1. Output a signal corresponding to the intensity of the image being Similarly, the photoelectric conversion unit 2222a-2 of the focus detection pixel 222a-2 passes through the distance measurement pupil 351, and the intensity of the image formed on the microlens 2221a-2 by the light beam AB1-2 directed to the microlens 2221a-2. Output a signal corresponding to

  In addition, the photoelectric conversion unit 2222b-1 of the focus detection pixel 222b-1 passes through the distance measurement pupil 352, and the intensity of the image formed on the microlens 2221b-1 by the light beam AB2-1 directed to the microlens 2221b-1 Output the corresponding signal. Similarly, the photoelectric conversion unit 2222b-2 of the focus detection pixel 222b-2 passes through the distance measurement pupil 352, and the intensity of the image formed on the microlens 2221b-2 by the light beam AB2-2 directed to the microlens 2221b-2. Output a signal corresponding to

  Then, the outputs of the photoelectric conversion units 2222 a and 2222 b of the first focus detection pixel 222 a and the second focus detection pixel 222 b described above are combined into output groups corresponding to the distance measuring pupil 351 and the distance measuring pupil 352, respectively. Data on the intensity distribution of a pair of images formed on the focus detection pixel array by the focus detection light beams passing through each of the distance measurement pupil 351 and the distance measurement pupil 352 is obtained.

Here, in the present embodiment, when obtaining such output data, the pixel obtained by adding the output data of the first focus detection pixel row L1 and the output data of the second focus detection pixel row L2 Obtain addition output data. Specifically, among the pixels constituting the output of the pixel A1 _L1 of the first focus detection pixel row L1 and the second focus detection pixel row L2 shown in FIG. And the output of the pixel A1 _L2 that received the light to obtain a pixel addition output I _A1 . Similarly, among the pixels constituting the output of the pixel B1 _L1 of the first focus detection pixel row L1 and the pixels constituting the second focus detection pixel row L2, a pixel B1 _L2 which has received the focus detection light flux passing through the same distance measurement pupil And the output of the pixel addition circuit to obtain a pixel addition output _I.sub.B1 . Hereinafter, likewise, obtain _{A2 L1} and _{A2 I} A2 from the output of _{L2, B2 L1} and _{B2 I} B2 from the output of _{L2, A3 L1} and _{A3 I} A3 from the output of _{L2, B3 L1} and _{I B3} from the output of _{B3 L2} .

Then, using the obtained pixel addition output, a data string based on the first focus detection pixel 222a, that is, the first image data string I _A1 , I _A2 , I _A3,. . . , I _An and a data string based on the second focus detection pixel 222 b, that is, a second image data string I _B1 , I _B2 , I _B3,. . . , I _Bn and performing a correlation operation shown in the following equation (1) while relatively shifting them in a one-dimensional manner.
C (k) =. SIGMA. | I.sub.A _{(n + k)} -I.sub.B _(n) ... (1)
In the above equation (1), the Σ operation represents the cumulative operation (phase-sum operation) for _{n, and} in the range in which data of I _{A (n + k)} and I _{B (n)} exist according to the image shift amount k. It is limited. The image shift amount k is an integer, and is a shift amount in units of the pixel interval of each of the focus detection pixels 222a and 222b. In the calculation result of the equation (1), the correlation amount C (k) becomes minimum (the smaller the degree of correlation, the higher the degree of correlation) in the shift amount where the correlation between the pair of image data is high.

Then, the correlation amount C (k) is calculated according to the above equation (1), and the defocus amount df is calculated according to the following equation (2) on the basis of the shift amount x from which the minimum value C (x) of the correlation amount is obtained. Calculate In the above equation (2), k is a conversion factor (k factor) for converting the shift amount x for obtaining the minimum value C (x) of the correlation amount into the defocus amount.
df = x · k (2)

  FIG. 7 shows a graph representing the relationship between the correlation amount C (k) and the shift amount. FIG. 7 shows the relationship between the correlation amount C (k) and the shift amount in the in-focus state (state in which the defocus amount is zero).

  On the other hand, FIG. 8 shows a graph showing the relationship between the amount of correlation C (k) and the amount of shift when the image pickup device of the prior art (for example, JP 2012-226088 A mentioned above) is used. Also in FIG. 8, as in FIG. 7, the relationship between the correlation amount C (k) and the shift amount in the in-focus state (the state in which the defocus amount is zero) is shown. Here, in the prior art, only the output of each focus detection pixel constituting the first focus detection pixel line L1 of the present embodiment is used, and therefore, the following problems occur.

That is, in the prior art, since only the first focus detection pixel column L1 of the present embodiment is used, the first focus detection pixel 222a and the second focus detection pixel 222b are shifted by 0.5 pixels from each other. Of the first image data train I _A1 , I _A2 , I _A3 , _... Obtained by using these focus detection pixels. . . , I _An and second image data strings I _B1 , I _B2 , I _B3,. . . , I _Bn become data mutually shifted by 0.5 pixels. Therefore, as shown in FIG. 8, the minimum value of the correlation amount C (k) is also shifted by 0.5 pixels, and in such a case, the correlation amount C (k) is a minimum value. In order to calculate the shift amount and the defocus amount that indicate the in, it is necessary to use an interpolation operation or the like, and as a result, the focus detection accuracy may be reduced. Such a problem tends to be noticeable particularly when the contrast level of the output detected by the focus detection pixel is low.

  On the other hand, in the present embodiment, the imaging element 22 includes the first focus detection pixel line L1 and the second focus detection pixel line L2, and the first focus detection pixels 222a constituting each pixel line By disposing the second focus detection pixel 222b at a position shifted by 0.5 pixel and using the pixel addition output obtained by adding these pixel outputs, the problems of the prior art are effectively eliminated. It is That is, according to the present embodiment, as shown in FIG. 7, it is possible to accurately obtain the shift amount at which the correlation amount C (k) gives the minimum value in the in-focus state (the defocus amount is zero). Thereby, the focus detection accuracy can be appropriately improved. In particular, according to the present embodiment, even when the contrast level of the output detected by the focus detection pixel is low, the focus detection accuracy can be appropriately improved. In addition, according to the present embodiment, the output value can be increased by adding the pixel output, whereby the focus detection can be appropriately performed even when the shooting scene has low luminance. Furthermore, by providing the first focus detection pixel row L1 and the second focus detection pixel row L2, the focus detectable area can be made wider compared to the case where only the first focus detection pixel row L1 is used. Therefore, the possibility of becoming undetected can be reduced.

  In the present embodiment, as shown in FIG. 3, the first focus detection pixel line L1 and the second focus detection pixel line L2 are disposed at positions sandwiching the three imaging pixels 221. It is not particularly limited to the However, since the focus detection pixels 222a and 222b constituting each of the focus detection pixel arrays L1 and L2 do not provide an image output suitable for the photographed image, these focal points from the viewpoint of further enhancing the accuracy of the obtained photographed image. At the positions where the detection pixel arrays L1 and L2 are arranged, it is desirable to perform interpolation processing using the output of the imaging pixels 221 located in the periphery. Therefore, from such a viewpoint, it is preferable to arrange the first focus detection pixel row L1 and the second focus detection pixel row L2 at a position where at least one imaging pixel 221 is sandwiched. On the other hand, if the first focus detection pixel row L1 and the second focus detection pixel row L2 are too far apart, the difference in output pattern obtained between these pixel rows is large depending on the subject to be shot and the shooting scene. May be Therefore, in the present embodiment, as shown in FIG. 3, the first focus detection pixel row L1 and the second focus detection pixel row L2 are disposed at positions sandwiching the three imaging pixels 221.

  The calculation of the image shift amount by the phase difference detection method and the calculation of the defocus amount based on this are executed by the camera control unit 21.

  Further, when the output data of the first focus detection pixel row L1 and the output data of the second focus detection pixel row L2 are added to obtain the pixel addition output, an operation unit provided in the imaging device 22 is used. The pixel addition output may be obtained and transmitted to the camera control unit 21. Alternatively, the camera control unit 21 may output the output data of the first focus detection pixel row L1 from the imaging element 22. Alternatively, the output data of the second focus detection pixel row L2 may be acquired, and a pixel addition output may be obtained using these.

  Furthermore, in addition to the above, the camera control unit 21 reads the output of the imaging pixel 221 of the imaging element 22, and calculates the focus evaluation value based on the read pixel output. The focus evaluation value can be obtained, for example, by extracting the high frequency component of the image output from the imaging pixel 221 of the image sensor 22 using a high frequency transmission filter and integrating the same. It can also be determined by extracting high frequency components using two high frequency transmission filters having different cutoff frequencies and integrating them.

  Then, the camera control unit 21 sends a control signal to the lens control unit 37 to drive the focus lens 32 at a predetermined sampling interval (distance) to obtain a focus evaluation value at each position, and the focus evaluation value is maximum. The focus detection by the contrast detection method is performed to obtain the position of the focus lens 32 as the in-focus position. It should be noted that, for example, when the focus evaluation value is calculated while driving the focus lens 32, the in-focus position is further lowered twice after the focus evaluation value rises twice. It can obtain | require by performing calculations, such as an interpolation method, using the focus evaluation value of.

  Next, an operation example of the camera 1 in the present embodiment will be described along the flowchart shown in FIG.

  First, in step S1, the camera control unit 21 acquires output data of the imaging pixel 221 constituting the imaging element 22, and the first focus detection pixel 222a and the second focus detection pixel 222b.

  Next, in step S2, pixel addition output is calculated by performing pixel addition on the first focus detection pixel 222a and the second focus detection pixel 222b acquired in step S1 according to the method described above by the camera control unit 21. Is done. That is, in step S2, the output data of the first focus detection pixel row L1 and the output data of the second focus detection pixel row L2 are added according to the method described above, and the pixel addition output data obtained by this is obtained. As described above, the addition of the output data of the first focus detection pixel line L1 and the output data of the second focus detection pixel line L2 is performed by the calculation unit provided in the imaging device 22 instead of the camera control unit 21. It is good also as composition performed by.

In step S3, based on the pixel addition output data calculated in step S2 according to the above-described method, the first image data strings I _A1 , I _A2 , I _A3,. . . , I _An and a second image data string I _B1 , I _B2 , I _B3 ,... Based on the second focus detection pixel 222 b. . . , I _Bn and using them, the shift amount calculation is performed according to the above equation (1), and the shift calculation is performed to obtain the shift amount x at which the correlation amount C (k) can obtain the minimum value. In this case, an interpolation operation may be performed as necessary.

  Next, in step S4, the defocus amount is determined according to the above equation (2) based on the shift amount x at which the correlation amount C (k) determined in step S3 is obtained as the minimum value. Then, based on the determined defocus amount, calculation of the drive amount of the focus lens 32 and drive of the focus lens 32 are performed.

  As described above, focus detection of the optical system is performed.

  In the present embodiment, the imaging element 22 includes the first focus detection pixel line L1 and the second focus detection pixel line L2, and the first focus detection pixels 222a constituting each pixel line and the second focus The detection pixel 222 b is disposed at a position shifted by 0.5 pixel, and a pixel addition output obtained by adding these pixel outputs is used. Then, according to the present embodiment, it is possible to accurately obtain the shift amount at which the correlation amount C (k) gives the minimum value in the in-focus state (the state in which the defocus amount is zero). Can be properly enhanced.

Second Embodiment
Next, a second embodiment of the present invention will be described. In the second embodiment, the camera 1 shown in FIG. 1 has the same configuration as that of the first embodiment described above except that it has the configuration as described below and operates as described below. It is.

  That is, the second embodiment has the same configuration as that of the above-described first embodiment except that an imaging device 22a having a configuration as shown in FIG. 10 is provided as an imaging device. As shown in FIG. 10, in addition to the first focus detection pixel row L1 and the second focus detection pixel row L2, the imaging element 22a according to the second embodiment includes a third focus detection pixel row L3 and a fourth focus detection pixel. A row L4 is provided. Then, as shown in FIG. 10, regarding the arrangement of the first focus detection pixels 222a and the second focus detection pixels 222b constituting each of the focus detection pixel lines L1 to L4, the first focus detection pixel line L1 and the third focus detection The pixel array L3 has the same array, and the second focus detection pixel array L2 and the fourth focus detection pixel array L4 have the same array.

  Next, a method of calculating the pixel addition output in the second embodiment will be described with reference to FIG. FIG. 11 schematically shows only the first focus detection pixel 222a and the second focus detection pixel 222b constituting the four focus detection pixel rows L1 to L4 except the imaging pixel 221 from the imaging surface of the imaging element 22a shown in FIG. FIG.

  In the second embodiment, of the four focus detection pixel lines L1 to L4, the pixel output of the second focus detection pixel line L2 located near the center of these lines and the pixel output of the third focus detection pixel line L3. To calculate the 4-pixel addition output obtained by adding the 2-pixel addition output obtained and the pixel outputs of the four focus detection pixel arrays L1 to L4.

Specifically, the two-pixel addition output is obtained as follows. That is, the focus detection light flux passing through the same focusing pupil as that of the output of the pixel A1 _L2 of the second focus detection pixel row L2 and the pixels constituting the third focus detection pixel row L3 shown in FIG. The output of the pixel A1 _L3 is added to obtain a pixel addition output I _A1 . Similarly, among the pixels constituting the output of the pixel B1 _L2 of the second focus detection pixel row L2 and the pixels constituting the third focus detection pixel row L3, the pixel B1 _L3 receiving the focus detection light flux passing through the same distance measurement pupil And the output of the pixel addition circuit to obtain a pixel addition output _I.sub.B1 . Hereinafter, likewise, obtain _{A2 L2} and _{A2 I} A2 from the output of _{L3, B2 L2} and _{B2 L3 I} B2 from the output of, _{A3 L2} and _{A3 I} A3 from the output of _{L3, B3 L2} and _{B3 L3 I B3} from the output of . Thereby, a 2-pixel addition output is obtained.

Further, the 4-pixel addition output is obtained as follows. That is, the pixel A1 _{L1 of} the first focus detection pixel row L1, the pixel A1 _L2 of the second focus detection pixel row L2, the pixel A1 _L3 of the third focus detection pixel row _L3 , and the pixel A1 _{L4 of} the fourth focus detection pixel row _L4. The pixel addition output I _A1 is obtained by adding the four pixel outputs of Similarly, the pixel B1 _{L1 of} the first focus detection pixel row L1, the pixel B1 _L2 of the second focus detection pixel row L2, the pixel B1 _L3 of the third focus detection pixel row _L3 , and the pixel B1 of the fourth focus detection pixel row L4. _A pixel addition output I _A1 is obtained by adding the four pixel outputs of _L4 . Similarly, from the outputs of A2 _L1 and A2 _L2 and A2 _L3 and A2 _L4 , the outputs of I _A2 , B2 _L1 and B2 _L2 and B2 _L3 and B2 _L4 from I _B2 , A3 _L1 and A3 _L2 and A3 _L3 and A3 _L4 I _B3 is obtained from the outputs of I _A3 , B3 _L1 , B3 _L2 , B3 _L3 and B3 _L4 . Thereby, 4-pixel addition output is obtained.

  Next, an operation example of the camera 1 in the second embodiment will be described along the flowchart shown in FIG.

  First, in step S101, as in step S1 shown in FIG. 9, the camera control unit 21 outputs the output data of the imaging pixel 221 and the first focus detection pixel 222a and the second focus detection pixel 222b that constitute the imaging device 22. Acquisition is performed.

  Next, in step S102, the camera control unit 21 performs pixel addition on the first focus detection pixel 222a and the second focus detection pixel 222b acquired in step S1 in accordance with the above-described method, thereby performing 2-pixel addition output and Calculation of 4-pixel addition output is performed. The calculation of the 2-pixel addition output and the 4-pixel addition output may be performed by an operation unit provided in the imaging device 22a instead of the camera control unit 21.

  In step S103, it is determined whether the signal level and the contrast level of the two-pixel addition output calculated in step S102 are equal to or greater than a predetermined determination threshold. The predetermined determination threshold used at this time is set to a value that can determine whether the 2-pixel addition output has a signal level and a contrast level sufficient to perform focus detection.

  In step S104, as a result of the determination in step S103, it is determined whether the signal level of the 2-pixel addition output and the contrast level are equal to or greater than a predetermined determination threshold, ie, the 2-pixel addition output is sufficient to perform focus detection. A determination is made as to whether or not the signal level and the contrast level are provided. If the signal level of the 2-pixel addition output and the contrast level are equal to or higher than the predetermined determination threshold, the process proceeds to step S105, and in step S105, the 2-pixel addition output is selected as an output used for focus detection calculation. On the other hand, when the signal level and the contrast level of the 2-pixel addition output are less than the predetermined determination threshold, the process proceeds to step S106, and the 4-pixel addition output is selected as the output used for the focus detection calculation in step S106.

Next, the process proceeds to step S107, and in step S107, using the pixel addition output (ie, 2-pixel addition output or 4-pixel addition output) selected in step S105 or step S106, the first focus detection pixel 222a is selected. Image data sequences I _A1 , I _A2 , I _A3,. . . , I _An and a second image data string I _B1 , I _B2 , I _B3 ,... Based on the second focus detection pixel 222 b. . . , I _Bn and using them, the shift amount calculation is performed according to the above equation (1), and the shift calculation is performed to obtain the shift amount x at which the correlation amount C (k) can obtain the minimum value. In this case, an interpolation operation may be performed as necessary.

  Next, the process proceeds to step S108, where the defocus amount is determined according to the above equation (2) based on the shift amount x at which the correlation amount C (k) obtained in step S107 obtains the minimum value. Then, based on the determined defocus amount, calculation of the drive amount of the focus lens 32 and drive of the focus lens 32 are performed.

  As described above, focus detection of the optical system is performed.

  According to the second embodiment, the imaging element 22a includes four focus detection pixel rows L1 to L4, and the first focus detection pixel 222a and the second focus detection pixel 222b that constitute each pixel row Are arranged at positions shifted by 0.5 pixel, and these two pixel outputs are added to obtain a 2-pixel addition output and a 4-pixel addition output. Then, according to the second embodiment, one of the two-pixel addition output and the four-pixel addition output is selected based on the signal level and the contrast level, whereby the focus detection accuracy can be made more appropriately. It can be enhanced. That is, when two-pixel addition output also has sufficient signal level and contrast level, the pixel outputs of the second focus detection pixel row L2 and the third focus detection pixel row L3 located relatively close are added Therefore, the influence of the difference in output pattern obtained between pixel columns can be made extremely low by using the two-pixel addition output obtained thereby. Alternatively, according to the second embodiment, in the 2-pixel addition output, when the signal level or the contrast level is insufficient, the signal level and the contrast level can be increased by using the 4-pixel addition output, thereby The focus detection accuracy can be more appropriately improved.

  In the above, it is determined whether the signal level of the 2-pixel addition output and the contrast level are equal to or more than a predetermined determination threshold, and 2-pixel addition output and 4-pixel addition output as pixel addition output used for focus detection. Although the configuration in which the camera control unit 21 performs the determination as to which of the above is used is illustrated, these may be performed by the imaging element 22a.

  In the above description, the pixel output of the second focus detection pixel row L2 and the third focus detection pixel row L3 is used to calculate the two-pixel addition output, but the first focus detection pixel row L1 and the first focus detection pixel row L1 The pixel output of the second focus detection pixel row L2 may be used, or the pixel output of the third focus detection pixel row L3 and the fourth focus detection pixel row L4 may be used.

  Furthermore, when calculating the 4-pixel addition output, weighting processing may be performed on the pixel output of each focus detection pixel column in order to adjust the degree of contribution. That is, for example, among the four focus detection pixel lines L1 to L4, four focus detection pixel lines L2 and L3 located near the center of these lines are obtained as compared with the focus detection pixel lines L1 and L4. The pixel outputs can be weighted and added so as to increase the degree of contribution when calculating the addition output.

Third Embodiment
Next, a third embodiment of the present invention will be described. In the third embodiment, the camera 1 having the same configuration as that of the second embodiment has the same configuration as that of the above-described second embodiment except that it operates as described below.

  Hereinafter, an operation example of the camera 1 in the third embodiment will be described along the flowchart shown in FIG.

  First, in steps S201 and S202, as in steps S101 and S102 shown in FIG. 12, the camera control unit 21 controls the imaging pixel 221, the first focus detection pixel 222a, and the second focus detection pixel 222b that constitute the imaging device 22. Acquisition of output data and calculation of 2-pixel addition output and 4-pixel addition output are performed.

  Next, in step S203, the focus detection pixel outputs (that is, the outputs not subjected to pixel addition) of the focus detection pixel arrays L1 to L4 acquired in step S201, and the 2-pixel addition output calculated in step S102, A determination is made as to whether the signal level and the contrast level are above a predetermined determination threshold. As the determination threshold used in this case, the same determination threshold may be used for the focus detection pixel output of each of the focus detection pixel arrays L1 to L4 and the 2-pixel addition output, but it is preferable to use different determination thresholds, When different determination threshold values are used, the focus detection pixel output of each of the focus detection pixel rows L1 to L4 not subjected to pixel addition has a threshold value higher than that of 2-pixel addition output in terms of securing focus detection accuracy. It is desirable to use.

  In step S204, as a result of the determination in step S203, the signal level and the contrast level of the focus detection pixel output (that is, the output not subjected to pixel addition) of each of the focus detection pixel arrays L1 to L4 acquired in step S201 are predetermined. It is determined whether the focus detection pixel output of each of the focus detection pixel arrays L1 to L4 has a signal level and a contrast level sufficient to perform focus detection. To be done. If the signal level and the contrast level of the focus detection pixel output of each of the focus detection pixel lines L1 to L4 are equal to or more than the predetermined determination threshold, the process proceeds to step S205, and in step S205, of the focus detection pixel lines L1 to L4 The pixel output of the focus detection pixel row having the highest contrast level is selected as the output used for the focus detection calculation.

  On the other hand, when it is determined in step S204 that the signal level and the contrast level of the focus detection pixel output of each of the focus detection pixel rows L1 to L4 are less than the predetermined determination threshold, the process proceeds to step S206. In step S206, as in step S104 shown in FIG. 12, it is determined whether the signal level of the 2-pixel addition output and the contrast level are equal to or greater than a predetermined determination threshold, that is, 2-pixel addition output performs focus detection. A determination is made as to whether it has sufficient signal levels and contrast levels. If the signal level of the 2-pixel addition output and the contrast level are equal to or more than the predetermined determination threshold, the process proceeds to step S207, and the 2-pixel addition output is selected as an output used for focus detection calculation. On the other hand, if the signal level and the contrast level of the two-pixel addition output are less than the predetermined determination threshold, the process proceeds to step S208, and the four-pixel addition output is selected as an output used for focus detection calculation.

  Next, the process proceeds to step S209, and the selected pixel output (that is, the pixel output of the focus detection pixel column having the highest contrast level, or the 2-pixel addition output or the 4-pixel addition output) as in step S107 shown in FIG. After the shift amount calculation has been performed using the above, the process proceeds to step S210, where the defocus amount is calculated as in step S108 shown in FIG.

  According to the third embodiment, even if the focus detection pixel output of each of the focus detection pixel arrays L1 to L4 not subjected to the pixel addition has a sufficient signal level and contrast level secured, the pixels not subjected to the pixel addition By using the output, it is possible to suppress the influence of the difference in output pattern obtained between the elementary strings.

Fourth Embodiment
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the camera 1 shown in FIG. 1 has the same configuration as that of the first embodiment described above except that it has the configuration as described below and operates as described below. It is.

  The fourth embodiment has the same configuration as that of the above-described first embodiment except that an imaging device 22b having a configuration as shown in FIG. 14 is provided as an imaging device. As shown in FIG. 14, the imaging element 22 b according to the fourth embodiment includes a third focus detection pixel row L <b> 3 in addition to the first focus detection pixel row L <b> 1 and the second focus detection pixel row L <b> 2. Then, as shown in FIG. 14, regarding the arrangement of the first focus detection pixels 222a and the second focus detection pixels 222b, the first focus detection pixel row L1 and the third focus detection pixel row L3 are arranged in the same manner. On the other hand, in the second focus detection pixel row L2, the first focus detection pixels 222a and the second focus detection pixels 222b are 0 in the X-axis direction with respect to the first focus detection pixel row L1 and the third focus detection pixel row L3. .5 Pixels are offset.

  Next, the method of calculating the pixel addition output in the fourth embodiment will be described with reference to FIG. FIG. 15 schematically shows only the first focus detection pixel 222a and the second focus detection pixel 222b constituting the three focus detection pixel rows L1 to L3 except for the imaging pixel 221 from the imaging surface of the imaging element 22b shown in FIG. FIG.

  In the fourth embodiment, the pixel outputs of three focus detection pixel arrays L1 to L3 are added by adding predetermined weights (predetermined degrees of contribution) to calculate pixel addition outputs. Specifically, since the first focus detection pixel row L1 and the third focus detection pixel row L3 are arranged in the same arrangement, the pixel outputs different in arrangement (first focus detection pixel row L1 and third focus detection pixel row The contribution of the pixel outputs of the first focus detection pixel row L1 and the third focus detection pixel row L3 is set so that the pixel addition output of L3 and the pixel output of the second focus detection pixel row L2 have the same size, For example, it is set to 0.5, and the contribution of the pixel output of the second focus detection pixel line L2 is set to 1, for example. Thus, the pixel outputs of the pixel outputs of the first focus detection pixel row L1, the second focus detection pixel row L2, and the third focus detection pixel row L3 can be weighted at a ratio of 1: 2: 1, respectively. Pixel outputs in which the pixel outputs of the first focus detection pixel row L1, the second focus detection pixel row L2, and the third focus detection pixel row L3 are respectively weighted by a ratio of 1: 2: 1 by adding the pixel outputs An addition output can be obtained.

For example, in the example shown in FIG. 15, the output of the pixel A1 _L1 of the first focus detection pixel column L1, the output of the pixel A1 _L2 of the second focus detection pixel column L2, and the pixel A1 L3 of the third focus detection pixel column _L3. And weighted at a ratio of 1: 2: 1 to obtain a pixel addition output I _A1 . Similarly, the output of the pixel B1 _L1 of the second focus detection pixel row L1, the output of the pixel B1 _L2 of the second focus detection pixel row L2, and the output of the pixel B1 _L3 of the third focus detection pixel row L3 are respectively 1 Weighted and added at a ratio of 2: 1 to obtain a pixel addition output I _B1 . Hereinafter, similarly, 1 the output of _{A2 L1} and _{A2 L2} and _{A2 L3:} 2: pixel addition output _{I A2} by adding weighted 1 ratio, _{B2 L1} and _{B2 L2} and _{B2 L3} of the output 1 : Adds the pixel addition output I _B2 by weighting at a ratio of 2: 1 and adds the outputs of A3 _L1 , A3 _L2 and A3 _L3 at a ratio of 1: 2: 1 and adds the pixel addition output the I _A3, 1 the output of _{B3 L1} and _{B3 L2} and _{B3 L3:} 2: get pixel addition output _{I B3} by adding weighted 1 ratio. Note that weighting of the pixel output may be performed by the camera control unit 21 or may be performed by an operation unit provided in the imaging device 22a.

  Next, an operation example of the camera 1 in the fourth embodiment will be described along the flowchart shown in FIG.

  First, in step S301, the camera control unit 21 configures the imaging pixels 221 constituting the imaging device 22, and the first focus detection pixel row L1, the second focus detection pixel row L2, and the third focus detection pixel row L3. Output data of the first focus detection pixel 222a and the second focus detection pixel 222b is acquired.

  Next, in step S302, the camera control unit 21 weights the pixel outputs of the first focus detection pixels 222a and the second focus detection pixels 222b of the first to third focus detection pixel arrays L1 to L3 acquired in step S301. To be done. For example, the camera control unit 21 multiplies the contribution of 0.25 for the pixel outputs of the first focus detection pixel 222a and the second focus detection pixel 222b of the first focus detection pixel row L1 and the third focus detection pixel row L3, respectively. The first focus detection pixel row L1 and the second focus detection pixel row L2 are obtained by multiplying the pixel outputs of the first focus detection pixel 222a and the second focus detection pixel 222b of the second focus detection pixel row L2 by the degree of contribution 0.5. The pixel outputs of the third focus detection pixel line L3 are weighted at a ratio of 1: 2: 1, respectively.

  In step S303, addition of the pixel output weighted in step S302 is performed. Then, in step S304, calculation of the shift amount is performed based on the pixel addition output added in step S303, and then the process proceeds to step S305, and calculation of the defocus amount is performed based on the calculated shift amount. It will be. The calculation of the shift amount and the defocus amount can be performed in the same manner as step S3 and step S4 of the first embodiment.

  As described above, focus detection of the optical system is performed.

  According to the fourth embodiment, the imaging element 22a includes the three focus detection pixel rows L1 to L3 and the first focus detection pixel 222a and the second focus detection pixel 222b that constitute each pixel row. Are arranged at a position shifted by 0.5 pixel, and the pixel output is obtained by adding these pixel outputs. In particular, in the fourth embodiment, the pixel outputs of the first focus detection pixel row L1, the second focus detection pixel row L2, and the third focus detection pixel row L3 are respectively weighted and added at a ratio of 1: 2: 1. Then, as shown in FIG. 7, in the in-focus state (the defocus amount is zero), it is possible to accurately obtain the shift amount at which the correlation amount C (k) gives the local minimum value. Can be properly enhanced.

Fifth Embodiment
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, the camera 1 shown in FIG. 1 has the same configuration as that of the above-described first embodiment except that it operates as described below. Here, FIG. 17 is a flowchart showing an operation example of the camera 1 according to the fifth embodiment. The operation of the camera 1 according to the fifth embodiment will be described below with reference to FIG.

  First, in step S401, the camera control unit 21 determines whether the shutter release button provided on the operation unit 28 has been half-pressed (the first switch SW1 is turned on). If the first switch SW1 is turned on, the process proceeds to step S402. On the other hand, when the first switch SW1 is not turned on, the process waits in step S401 until the first switch SW1 is turned on.

  In step S402, it is determined that the focus detection process is activated, and the camera control unit 21 sets the pixel addition flag to off. As described above, in this embodiment, the pixel addition flag is set to OFF so that the addition of the pixel outputs of the first focus detection pixel row L1 and the second focus detection pixel row L2 is not performed at the start of focus detection processing. Do. Here, when the subject is not in focus, low frequency components are easily detected in the pixel output of the first focus detection pixel row L1 and the pixel output of the second focus detection pixel row L2. Furthermore, when the amount of blurring of the subject image is large, when the pixel output of the first focus detection pixel row L1 and the pixel output of the second focus detection pixel row L2 are added, the frequency component of the added pixel output is The waveform of the frequency component of the first focus detection pixel row L1 and the waveform of the frequency component of the second focus detection pixel row L2 are smoothed (frequency reduction), and detection of the object becomes more difficult. I will. Therefore, when focus detection processing is started, if the subject is not in focus and the possibility that the amount of blur is large is high, the detection accuracy of the subject is improved by setting the pixel addition flag to OFF. be able to.

  In step S403, as in step S1 of the first embodiment, the camera control unit 21 causes the camera control unit 21 to pick up an imaging pixel 221 that constitutes the imaging device 22, and the first focus detection pixel 222a and the second focus detection pixel. Acquisition of the output data of 222b is performed.

  In step S404, it is determined by the camera control unit 21 whether or not it is determined that the distance measurement can not be performed continuously a predetermined number of times or more. For example, when the defocus amount can not be calculated, or when it is determined that the reliability of the defocus amount is low, the camera control unit 21 can determine that distance measurement can not be performed. Then, if the determination that distance measurement is impossible is continuously performed a predetermined number of times or more by the previous process, the process proceeds to step S405, and the pixel addition flag is set to off. As described above, in the present embodiment, as a result of focus detection, if it is repeatedly determined that the distance measurement can not be performed a predetermined number of times or more, it is determined that the possibility that the amount of blurring of the subject image is large is high. The addition flag is set to OFF, and the addition of the pixel outputs of the first focus detection pixel row L1 and the second focus detection pixel row L2 is prohibited. As a result, when the amount of blur of the subject image is large, the addition of the pixel outputs of the first focus detection pixel row L1 and the second focus detection pixel row L2 is not performed, so the focus detection accuracy is enhanced as described above. be able to. The evaluation of the reliability of the defocus amount can be performed, for example, on the basis of the matching degree or the contrast of the pair of image data.

  In step S406, the camera control unit 21 determines whether the pixel outputs of the first focus detection pixel row L1 and the second focus detection pixel row L2 have low contrast. If the pixel outputs of the first focus detection pixel line L1 and the second focus detection pixel line L2 have low contrast, the process proceeds to step S407, and the pixel addition flag is set to off. Here, even when the pixel output has low contrast, the added frequency component of the pixel output is the waveform of the frequency component of the first focus detection pixel row L1, and the waveform of the frequency component of the second focus detection pixel row L2. Smoothing (frequency reduction) may be performed more than in some cases, and detection of an object may be more difficult. Therefore, by setting the pixel addition flag to OFF, the addition of the pixels of the first focus detection pixel column L1 and the second focus detection pixel column L2 is prohibited. Thereby, the focus detection accuracy can be enhanced. On the other hand, when the subject is not in low contrast, the process proceeds to step S408.

  In step S408, the camera control unit 21 determines whether the subject is high in luminance and it is determined in the previous process that distance measurement is not possible. In the present embodiment, the ISO sensitivity is set based on the brightness of the subject so that an exposure suitable for focus detection can be obtained, and the camera control unit 21 sets the set ISO sensitivity to a predetermined value or less. In some cases, it can be determined that the brightness of the subject is equal to or greater than a predetermined brightness value (the subject is in high brightness). Then, if it is determined that the subject has high luminance and distance measurement is impossible in the previous process, the process proceeds to step S409, and the pixel addition flag is set to off. Here, when the ISO sensitivity is low, the influence of noise is relatively small, so a relatively high S / N ratio can be obtained without addition of pixel outputs. Therefore, the camera control unit 21 prohibits the addition of the pixels of the first focus detection pixel row L1 and the second focus detection pixel row L2 when the subject has high luminance and distance measurement is impossible. Can improve the focus detection accuracy. On the other hand, if the subject has low luminance or if it is determined that distance measurement is possible, focus detection accuracy can be further improved by performing pixel addition, so the pixel addition flag is not set off. The process proceeds to step S410.

  In step S410, the camera control unit 21 determines whether the pixel addition flag is set to on. If the pixel addition flag is set to on, the process proceeds to step S411. If the pixel addition flag is set to off, the process proceeds to step S412.

  In step S411, since the pixel addition flag is set to ON, pixel addition is performed on the first focus detection pixel 222a and the second focus detection pixel 222b as in step S2 of the first embodiment. The output is calculated.

  On the other hand, in step S412, since the pixel addition flag is set to OFF, addition is not performed for the pixel outputs of the first focus detection pixel 222a and the second focus detection pixel 222b, and the first focus detection pixel 222a and the second focus Only acquisition of the pixel output of the detection pixel 222b is performed.

  Then, in step S413, shift amount calculation is performed based on the pixel addition output added in step S411, or the pixel output of the first focus detection pixel 222a and the second focus detection pixel 222b acquired in step S412. Then, in step S414, the defocus amount is calculated based on the shift amount calculated in step S413, and in the following step S415, the focus lens 32 is driven based on the calculated defocus amount. Specifically, the camera control unit 21 calculates the lens drive amount necessary to drive the focus lens 32 to the in-focus position based on the defocus amount calculated in step S414, and calculates the lens drive. The amount is sent to the focus lens drive motor 36 via the lens control unit 37. As a result, the focus lens drive motor 36 drives the focus lens 32 based on the calculated lens drive amount.

  In step S416, the camera control unit 21 determines whether or not the half-depression of the shutter release button is released (the first switch SW1 is turned off). If the first switch SW1 is on, the process proceeds to step S417, the pixel addition flag is set to on, and the process returns to step S403. As a result, the focus detection process is not activated, and it is not determined that the distance measurement can not be performed continuously a predetermined number of times or more, and the pixel output is not low contrast and the subject is not high luminance and distance measurement impossible. In step S411, addition of pixel outputs is performed. On the other hand, when the first switch SW1 is off, the operation of the camera 1 of FIG. 16 is ended.

  In step S417, whether the amount of blurring of the subject image is equal to or less than a predetermined value, or whether driving of the focus lens 32 has been started after activation of the focus detection process (after half-press operation of the shutter release button) It is determined whether or not the pixel addition flag is set to ON when the amount of blurring of the subject image becomes equal to or less than a predetermined value, or when the driving of the focus lens 32 is started after the start of focus detection processing. It is also good.

  As described above, focus detection of the optical system is performed.

  According to the fifth embodiment, when focus detection processing is started, if the determination that distance measurement is impossible is repeated several times or more, if the pixel output has low contrast, or if the subject has high brightness and measurement When it is determined that distance measurement is impossible, pixel addition is prohibited by turning off the pixel addition flag. That is, when the object is not in focus, the frequency components detected by the first focus detection pixel row L1 and the frequency components detected by the second focus detection pixel row L2 are low because there are few high frequency components. easy. In such a case, when the pixel output of the first focus detection pixel row L1 and the pixel output of the second focus detection pixel row L2 are added, the added frequency components (first image data row and second The waveform of the image data sequence is smoothed, which makes detection of the subject more difficult. Therefore, when focus detection processing is started, if it is determined that distance measurement is impossible several times or more, if the subject has low contrast, or if it is determined that the object has high brightness and distance measurement is not possible. For example, when there is a high possibility that the amount of blurring of the subject image is large, the detection accuracy of the subject can be enhanced by prohibiting the addition of the pixel output.

  As mentioned above, although embodiment of this invention was described, embodiment mentioned above is described in order to facilitate an understanding of this invention, and is not described in order to limit this invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

  For example, in the embodiment described above, the aspect of obtaining the addition pixel output by adding the pixel output of each focus detection pixel column is illustrated, but instead of the pixel addition output, the pixel output of each focus detection pixel column is averaged The obtained average pixel output may be calculated and used to perform focus detection calculation. In addition, when calculating the average output, weighting processing may be performed to adjust the degree of contribution for the pixel output of each focus detection pixel column, as in the case of calculating the pixel addition output.

  Furthermore, in the embodiment described above, the configuration including two or four focus detection pixel rows is exemplified, but the number of focus detection pixel rows is not limited to these and can be set as appropriate. For example, when three focus detection pixel lines L1 to L3 are provided as the focus detection pixel lines, the focus detection pixel lines L1 and the focus detection pixel lines L3 are generally arranged in the same arrangement with respect to the arrangement of focus detection pixels. The focus detection pixel line L2 is shifted by 0.5 pixels. Therefore, in such a case, when the pixel addition output is obtained by pixel addition of these, and when the average output is calculated by averaging, the pixel outputs of the focus detection pixel row L1 and the focus detection pixel row L3 are obtained. It is desirable to set the degree of contribution to, for example, 0.5, and set the degree of contribution of the pixel output of the focus detection pixel column L2 to, for example, 1.

  Further, the arrangement of the first focus detection pixels 222a and the second focus detection pixels 222b constituting each focus detection pixel row may be at least those alternately arranged on the same row, for example, as shown in FIG. As in the focus detection pixel lines L1a and L1b shown in and the focus detection pixel lines L2a and L2b shown in FIG. 19, the normal imaging pixels 221 may be included in the focus detection pixel lines.

  Furthermore, in the fourth embodiment described above, as illustrated in FIG. 14, the configuration in which the imaging element 22b includes the three focus detection pixel arrays L1 to L3 is illustrated, but the present invention is not limited to this configuration. As shown, the imaging element 22e may be configured to include five focus detection pixel rows L1 to L5. In this case, the first focus detection pixel row L1, the third focus detection pixel row L3, and the fifth focus detection pixel row L5 have the same pixel arrangement, and the second focus detection pixel row L2 and the fourth focus detection pixel row L4 Since the pixel arrangement is the same, when the pixel addition output is obtained by pixel addition of these, and when the average output is calculated by averaging, the first focus detection pixel row L1, the third focus detection pixel row L3, The degree of contribution of the pixel output of the fifth focus detection pixel line L5 is set, for example, to 0.16, and the degree of contribution of the pixel output of the second focus detection pixel line L2 and the fourth focus detection pixel line L4 is, for example, 0.1. Set to 25. That is, the pixel outputs of the focus detection pixel arrays L1 to L5 are added at a ratio of 2: 3: 2: 3: 2. As a result, it is possible to accurately obtain the shift amount at which the correlation amount C (k) gives the minimum value in the in-focus state (the state in which the defocus amount is zero), thereby appropriately enhancing the focus detection accuracy. it can.

  In the example shown in FIG. 20, for example, when the contrast of the subject in the fourth focus detection pixel line L4 is low, the first focus detection pixel line L1, the second focus detection pixel line L1, excluding the fourth focus detection pixel line L4. Focus detection may be performed based on the pixel outputs of the focus detection pixel line L2, the third focus detection pixel line L3, and the fifth focus detection pixel line L5. In this case, the contribution of the pixel outputs of the first focus detection pixel row L1, the third focus detection pixel row L3, and the fifth focus detection pixel row L5 is set to, for example, 0.16, and the second focus detection pixel row L2 is set. The degree of contribution of the pixel output can be set, for example, to 0.5. That is, the pixel outputs of the focus detection pixel arrays L1 to L3 and L5 are added at a ratio of 1: 3: 1: 1. As a result, in the in-focus state (state in which the defocus amount is zero), the shift amount at which the correlation amount C (k) gives the minimum value can be accurately determined, and the focus detection accuracy can be appropriately increased.

  In the embodiment described above, the configuration in which the contribution degree of the pixel output is set to 1 in total is described as an example. However, the present invention is not limited to this configuration. As long as the above is true, the degree of contribution may be set to a value other than 1 in total. For example, in the example shown in FIG. 20, the contribution of the pixel output of the first focus detection pixel line L1, the third focus detection pixel line L3, and the fifth focus detection pixel line L5 is set to 1, for example, and the second focus detection is performed. The degree of contribution of the pixel outputs of the pixel line L2 and the fourth focus detection pixel line L4 can be set to, for example, 1.5.

  Furthermore, in the example illustrated in FIG. 14, for example, in the third focus detection pixel row L3, when the contrast of the subject is higher than that of the first focus detection pixel row L1, the pixel output of the third focus detection pixel row L1 contributes The degree may be set to be larger than the contribution degree of the pixel output of the first focus detection pixel row L1. For example, in the above-described example, the contribution of the pixel outputs of the first focus detection pixel line L1 and the third focus detection pixel line L3 is set to 0.5, and the contribution of the pixel output of the second focus detection pixel line L2 is In the third focus detection pixel column L3, when the contrast of the subject is higher than that of the first focus detection pixel column L1, the contribution of the pixel output of the first focus detection pixel column L1 is 0.25. The degree of contribution of the pixel output of the second focus detection pixel line L2 may be set to 1, and the degree of contribution of the pixel output of the third focus detection pixel line L3 may be set to 0.75.

  In addition, in the fifth embodiment described above, the pixel addition flag is turned off after the focus detection is started (step S402), and the pixel addition is prohibited at the start of the focus detection process. The “at the time of start of focus detection process” is not limited to this timing, and may be within a predetermined time from the start of focus detection, or may be repeated until the focus detection process is repeated a predetermined number of times.

Reference Signs List 1 digital camera 2 camera body 21 camera control unit 22, 22a to 22e imaging element 221 imaging pixel L1 to L5 focus detection pixel row 222a first focus detection pixel 222b second focus detection pixel 3 lens Lens barrel 32 ... focus lens 36 ... focus lens drive motor 37 ... lens control unit

Claims (14)

An image sensor including a plurality of detection units including a plurality of focus detection pixels arranged in a first direction in a second direction intersecting the first direction, and capturing an image formed by the optical system and outputting a signal; ,
A first operation of calculating the shift amount between the position of the image by the optical system and the imaging device according to a signal from one of the detection units using a first signal output from one of the detection units; A calculation unit that performs one of a second calculation of calculating the amount of deviation using a second signal output from the plurality of detection units;
Detecting device. In the detection device according to claim 1,
The detection device which performs any one of the first calculation and the second calculation according to any one of the magnitude and the contrast of the first signal. In the detection device according to claim 2,
The detection device wherein the magnitude of the first signal when performing the first calculation is larger than the magnitude of the first signal when performing the second calculation. In the detection device according to claim 2,
The detection apparatus wherein the contrast value of the first signal in the case where the first calculation is performed by the calculation unit is higher than the contrast value of the first signal in the case where the second calculation is performed. The detection apparatus according to any one of claims 1 to 4.
The detection apparatus according to claim 1, wherein the second signal is a signal obtained by adding the signals output from the plurality of detection units. In the detection device according to any one of claims 1 to 5,
The second calculation performed by the calculation unit includes calculation of the amount of deviation using the second signal according to the second signal, and addition of the signal output from the detection unit to the second signal. The detection apparatus which performs any of calculating the said deviation using 3 signals. In the detection device according to claim 6,
The calculation unit calculates the amount of deviation using the second signal and calculates the amount of deviation using the third signal according to one of the magnitude of the second signal and the contrast of the output signal. Detection device to do either. The detection apparatus according to any one of claims 1 to 7.
The detection unit included in the image sensor includes a first pixel receiving light passing through the first area of the optical system and a second area different from the first area of the optical system. A detection device in which second pixels receiving light are alternately arranged in the first direction. In the detection device according to claim 8,
The detection device in which the first pixel and the second pixel are alternately arranged in the second direction in the imaging element. In the detection device according to claim 9,
The second calculation performed by the calculation unit is a coefficient determined according to the ratio of the number of first pixels to the number of second pixels in the second direction of the detection unit used in the second calculation. A detection apparatus for calculating the amount of deviation using a signal obtained by multiplying each of the signals output from the detection unit used in the second calculation and then adding them. A plurality of first pixels for receiving light passing through a first area of an optical system for forming an image of a subject;
An imaging element having a plurality of second pixels for receiving light that has passed through a second area different from the first area of the optical system;
A first signal output from a first pixel column consisting of a plurality of first pixels arranged in a first direction, and a second signal column consisting of a plurality of second pixels arranged in the first direction A first operation for calculating, from the first signal and the second signal, a value relating to the amount of deviation between the position of the image by the optical system and the imaging surface of the imaging device according to the second signal; A third signal generated in a third pixel row formed of a plurality of first pixels arranged at positions different from the first pixel row in the second direction intersecting the first direction, and arranged in the first direction The fourth signal front generated in the fourth pixel row formed of the plurality of second pixels arranged in the second direction and different from the second pixel row in the second direction is provided. A fifth signal and a sixth signal generated by adding to the first signal and the second signal A calculation unit for performing any of the second calculation for calculating a value relating to serial shift amount,
Detecting device.   An imaging device comprising the detection device according to any one of claims 1 to 11. A plurality of first pixels for receiving light passing through a first area of an optical system for forming an image of a subject;
A plurality of second pixels for receiving light passing through a second area different from the first area of the optical system;
A first signal generated in a first pixel row consisting of a plurality of the first pixels arranged in a first direction, and a second signal row generated from a plurality of the second pixels arranged in the first direction Second signal, which is disposed at a position different from the first pixel row in the second direction intersecting the first direction, and is generated in a third pixel row composed of a plurality of first pixels disposed in the first direction A third signal, a fourth signal generated in a fourth pixel column which is disposed at a position different from the second pixel column in the second direction and is formed of a plurality of second pixels arranged in the first direction, A fifth signal generated by adding a plurality of signals forming the first signal and a plurality of signals forming the third signal in the second direction, a plurality of signals forming the second signal, and the first signal And outputs a sixth signal generated by adding the plurality of signals constituting the four signals in the second direction. And an output unit that,
An imaging device having An imaging device comprising the imaging device according to claim 13.

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