JP2015034859A - Automatic focus adjustment lens device and photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic focus adjustment lens device using an image-surface phase difference sensor capable of automatic focus adjustment even in a large defocus state, without influencing on a video signal, in automatic focus adjustment in moving image photography and to provide a photographing system.SOLUTION: A lens device includes a focus group, a first diaphragm, a branching optical system branching a subject luminous flux through the focus group and the first diaphragm into an imaging luminous flux and a focus detection luminous flux, a sensor for imaging receiving the imaging luminous flux, the imaging-surface phase difference sensor acquiring the video signal and a phase difference signal from the focusing detection luminous flux, a second diaphragm arranged between the branching optical system and the image-surface phase difference sensor, means for acquiring a position where the automatic focus adjustment is performed in a photographed image, and control means for acquiring a focusing state by using the phase difference signal from the image-surface phase difference sensor and controlling the drive of the focus group and the second diaphragm, based on the focusing state. The control means controls the opening shape of the second diaphragm, based on the information of the position where the automatic focus adjustment is performed.

Description

  The present invention relates to an automatic focusing lens device and a photographing apparatus that separates a light beam for imaging and a light beam for focus detection and performs automatic focus adjustment based on the light beam for focus detection.

  An imaging surface phase difference sensor is known that allows a phase difference signal and a video signal to be output simultaneously by the imaging sensor by providing a structure having a plurality of photoelectric conversion units in one pixel in the imaging sensor (patent) Reference 1). Since the imaging surface phase difference sensor can detect focus by using a phase difference signal while photographing, moving image photographing can be performed while adjusting the focus. In addition, automatic focus adjustment using a contrast value can be performed using video signals acquired at the same time.

  However, this imaging surface phase difference sensor not only blurs the video signal in the defocused state, but also blurs the phase difference signal for use in automatic focus adjustment. For this reason, there is a problem that the contrast of the phase difference signal is greatly reduced at the time of large defocus, and the defocus amount cannot be calculated or the focusing accuracy is lowered.

  With respect to this problem, Patent Document 2 discloses a focus detection device that can detect a large defocus using an imaging surface phase difference sensor by providing means for shielding a part of a light beam in an imaging optical system. ing.

JP 2001-083407 A JP 2001-124984 A

  By providing the above-described light shielding means, large defocus can be detected. However, if this light shielding means is arranged on the same plane as the aperture stop or other than the plane having a pupil conjugate relationship, vignetting occurs due to the light shielding means in the light beam received by the off-axis pixel, and focusing accuracy is improved. Leading to a decline. In Patent Document 2, since a means for shielding light is arranged on the same surface as the aperture stop, not only the phase difference signal but also the imaging light beam used for the video signal is similarly stopped, and the light amount of the video signal and the object field are reduced. Affects depth. Therefore, it is not suitable for moving image shooting in which images are continuously acquired.

  On the other hand, when a means for shielding light is provided on another surface having a pupil conjugate relationship, it is necessary to use a secondary imaging optical system sandwiching the primary imaging surface, which leads to an increase in the number of lenses and an increase in the total length. .

  Accordingly, an object of the present invention is to provide an automatic focusing lens device and an imaging system using an imaging surface phase difference sensor capable of automatic focusing even in large defocus without affecting the video signal during automatic focusing in moving image shooting. Is to provide.

  In order to achieve the above object, a lens apparatus according to the present invention includes a focus lens group, a first diaphragm, and a focus detection of a light beam from a subject through the focus lens group and the first diaphragm with an imaging light beam. A branching optical system for branching into a luminous flux for imaging, an imaging sensor for receiving the imaging luminous flux, an imaging surface phase difference sensor for obtaining a video signal and a phase difference signal from the focusing detection luminous flux, and the branching optics A second aperture disposed between a system and the imaging plane phase difference sensor, means for obtaining a position for performing automatic focus adjustment in an image to be captured, and a phase difference obtained from the imaging plane phase difference sensor Control means for acquiring a focus state using a signal and controlling driving of the focus lens group and the second diaphragm based on the focus state, and the control means includes the automatic focus adjustment. Based on location information Controlling said second throttle opening shape, characterized in that.

  According to the present invention, there is provided an automatic focusing lens device and an imaging system using an imaging surface phase difference sensor capable of automatic focusing even in large defocus without affecting a video signal during automatic focusing in moving image shooting. Can do.

It is a pixel structure of an imaging surface phase difference sensor. It is the schematic which projected each photoelectric conversion part of the pixel on an axis | shaft on the exit pupil plane of a 1st aperture_diaphragm | restriction. It is a figure of the exit pupil surface at the time of projecting each photoelectric conversion part of an on-axis pixel on an exit pupil surface. It is an example of two brightness | luminance signals obtained from each photoelectric conversion part at the time of small defocusing. It is an example of two brightness | luminance signals obtained from each photoelectric conversion part at the time of a large defocus. It is a block diagram of Example 1 of the automatic focusing lens device of the present invention. It is a figure which shows the light beam utilized for automatic focus adjustment at the time of large defocusing when the 2nd aperture is not decentered appropriately with respect to the automatic focus adjustment area. It is an example of two brightness | luminance signals from each photoelectric conversion part at the time of not decentering a 2nd aperture_diaphragm | restriction appropriately with respect to an automatic focus adjustment area. 2 is an automatic focus adjustment flow according to the first embodiment. It is a figure which shows the light beam utilized for the automatic focus adjustment at the time of large defocusing when the second aperture is appropriately decentered with respect to the automatic focus adjustment area. This is an automatic focus adjustment flow in the case where the operation reliability is low even when the second aperture is stopped. FIG. 6 is a structural diagram of Example 2 of the automatic focusing lens device of the present invention. It is a figure of the light beam utilized for automatic focus adjustment when the exit pupil plane is missing due to vignetting. It is a figure which shows that the influence of a vignetting can be reduced by adjusting a 2nd aperture_diaphragm | restriction. 6 is an automatic focus adjustment flow according to the second embodiment. 10 is a sensor layout used in the imaging surface phase difference sensor according to the third embodiment. 10 is an automatic focus adjustment flow according to the third embodiment. In Example 4, it is a figure which shows arrangement | positioning of the two aperture members with respect to a ranging direction. In Example 4, it is the schematic at the time of decentering appropriately the 2nd aperture_diaphragm | restriction with respect to an auto-focusing area at the time of large defocusing. FIG. 10 is a structural diagram of Embodiment 5 of the automatic focusing lens device of the present invention. 10 is an automatic focus adjustment flow according to a fifth embodiment.

  The principle of phase difference detection of the imaging surface phase difference sensor used in the present invention and the influence of the change in F number on the light beam used for phase difference detection will be described.

  FIG. 1A shows a simple structural diagram of one pixel of the imaging surface phase difference sensor. One pixel has one microlens 101 and two photoelectric conversion units 102a and 102b. FIG. 1B shows the layout of the sensor used in this embodiment. The photoelectric conversion unit of each pixel of the Bayer array RGGB is divided into two.

  FIG. 2 is a diagram in which the photoelectric conversion units 102a and 102b of the pixels on the axis are projected onto the exit pupil 103 plane. The photoelectric conversion unit 102a is designed to be projected onto 104R on the exit pupil 103 plane. That is, the light beam emitted from 104R to the photoelectric conversion unit 102a is received and a luminance signal is output. Similarly, the photoelectric conversion unit 102b is designed to receive a light beam from the exit pupil plane 104L and output it as a luminance signal. In addition, regarding the off-axis pixels, the respective photoelectric conversion units are designed to be projected onto 104L and 104R on the exit pupil 103 plane.

  FIG. 3 is a diagram showing the entire area of the exit pupil 103 surface of FIG. The two projected photoelectric conversion units 104L and 104R divide the pupil so as to have sensitivity at different positions on the exit pupil 103 plane. Therefore, each photoelectric conversion unit 102a, 102b can be acquired as a phase difference signal by treating it as a separate luminance signal. Here, each sensitivity is shown on an ellipse, but the shape is not limited to this, and other shapes may be a semicircular shape, a rectangular shape, or the like.

  In order to obtain a video signal from the imaging surface phase difference sensor, the luminance signals of the two photoelectric conversion units 102a and 102b in the pixel are added. As a result, an output signal (luminance signal) is generated by the light flux from the entire exit pupil 103 of the first diaphragm.

  FIG. 4 is an example of a luminance signal. From these two luminance signals, a phase difference amount indicated by an arrow is calculated using a correlation calculation method.

  A specific operation of this correlation calculation process will be briefly described. One luminance signal is fixed, and the other luminance signal is shifted with respect to the pixel position. For each shift amount, the overlapping area of the two luminance signals is obtained. At this time, the shift amount that maximizes the overlapping area is calculated as the phase difference amount.

  Next, a change with respect to the F number of a light beam used for performing automatic focus adjustment will be described.

  Since the automatic focus adjustment using this imaging surface phase difference sensor also has a function of acquiring a video signal, the sum of two light beams used for focus adjustment is equal to the light beam of the entire exit pupil. Therefore, the light beam used for focus adjustment changes depending on the F number of the lens. When the F number is small, the baseline length (distance between pupil divisions), which is the distance between the centers of gravity of the two light beams received by each photoelectric conversion unit, becomes long. On the other hand, when the F number is large, the baseline length is shortened. Therefore, when the F number is small with respect to the predetermined defocus amount, the phase difference amount is larger than when the F number is large, so that the focusing accuracy is high.

However, when the F number is small, not only the video signal but also the luminance signal is blurred due to defocusing (the contrast of the video signal is lowered). When the amount of phase difference is small, a luminance signal whose image is almost shifted as shown in FIG. 4 can be obtained. However, when the amount of phase difference is large, the image is blurred, resulting in a gentle signal as shown in FIG. . Thus, if it becomes a signal of only a low frequency component, it will become difficult to detect an accurate phase difference amount.
Next, specific examples of the present invention will be described in detail with reference to the drawings.

  FIG. 6 is a configuration diagram of Embodiment 1 of the automatic focusing lens device 100 of the present invention, and shows a schematic configuration diagram as an imaging device to which a camera device 200 is connected. A focus lens group 1a, a first aperture stop 1b, and a branching optical system 1c are sequentially provided from the object side. The first light beam branched by the branching optical system 1 c is imaged by the imaging sensor 1 d of the camera device 200 connected to the lens device 100. On the image plane side of the second light beam branched by the branching optical system 1c, a second diaphragm 1e and an imaging surface phase difference sensor 1f are arranged at the position of the image surface of the second light beam. Further, it includes a focus control unit 1g for controlling the focus lens group, a calculation unit 1h for calculating a defocus amount from the phase difference signal, and a first diaphragm F number detection unit 1i. Furthermore, it has a storage means 1j for storing various values necessary for automatic focus adjustment, a second aperture control means 1k, and an automatic focus adjustment area acquisition means 1l.

  The second diaphragm 1e is not in a pupil conjugate relationship with the first diaphragm 1b. Therefore, the second diaphragm 1e has a function of changing the “opening state” of the diaphragm, that is, a function of changing the size of the opening and a function of decentering the position of the opening with respect to the optical axis position. Have both.

  FIG. 7 is a diagram showing a light beam received by an off-axis pixel when the second stop 1e is stopped when the second stop 1e is stopped in a symmetric shape about the optical axis. FIG. 7A shows the position and optical path of the second stop 1e, FIG. 7B shows the automatic focus adjustment area 105, and FIG. 7C shows the light flux on the exit pupil 103 surface of the first stop 1b. Show. The white color in FIG. 7C indicates that the light beam is passed, and the black color indicates that the light beam is blocked. As shown in FIG. 7C, the light amount of the received light beam differs between 104L and 104R. Therefore, as shown in FIG. 8, the phase difference output signals are the signals output from the photoelectric conversion units 102a and 102b as shown in FIG. Different levels (indicated by arrows). If the balance of the amount of light received by each of the photoelectric conversion units 102a and 102b is lost, the accuracy of the correlation calculation decreases, leading to a decrease in focusing accuracy.

  FIG. 9 is a focus adjustment flow of this embodiment. Normally, with the second diaphragm 1e opened, a light beam having the same F number as that on the imaging side is received by the imaging surface phase difference sensor 1f, and based on the phase difference signal from the imaging surface phase difference sensor 1f, the calculation means 1h The in-focus state is calculated, and the focus control unit 1g is controlled based on the in-focus state to perform automatic focus adjustment. When the phase difference amount cannot be calculated or the calculation reliability is low, such as in a large defocus state, automatic focusing is performed by reducing the second aperture 1e. Hereinafter, it will be described in detail with reference to the focus adjustment flow shown in FIG.

  First, in step S101, it is confirmed whether or not the automatic focus adjustment mode. In the automatic focus adjustment mode, in S102, the second diaphragm 1e is opened (the light beam used for focus adjustment is not focused).

  In S103, an automatic focus adjustment area acquisition unit 1l is used as an automatic focus adjustment area for specifying which position in the imaging plane phase difference sensor 1f (within the captured image) the focus information is to be acquired. Get from. As the automatic focus adjustment area acquisition means 11, for example, a means (pointing device such as a mouse or a joystick or a means for directly inputting a coordinate value in the screen) that can designate a predetermined area or position in the shooting screen is used. It is possible to do.

  In S104, it is determined in the imaging surface phase difference sensor whether the amount of light of the subject exceeds the threshold value. When it exceeds, it continues to S105, and when it does not exceed, it returns to the step of S101. As the light amount threshold value, the lowest light amount that can be focused by the storage unit 1j is stored in advance.

  In subsequent S105, the F number of the first diaphragm 1b is acquired by the F number detection means 1i of the first diaphragm.

  In S106, a correlation calculation is performed on the luminance signal based on the autofocus area, and a phase difference amount and a calculation reliability value are calculated. In S107, the reliability value of the calculation is compared with the threshold value stored in the storage unit 1j. The calculation reliability value is calculated based on the contrast value of the luminance signal. By including the contrast value in the reliability value, it is possible to determine whether the state is a large blur, and focus adjustment is not performed in a state where the accuracy is reduced due to a large defocus.

  Here, only the contrast value of the luminance signal is listed in the calculation of the reliability value, but the reliability value may be included including other elements such as the amount of noise.

  If it is determined in S107 that the reliability is high, the second aperture stop 1e is not operated, and automatic focus adjustment is performed with the same F number as that on the imaging side. In S108, the baseline length value stored in the storage means 1j is read based on the F number of the first aperture stop 1b. In S109, the defocus amount is calculated from the base line length and the phase difference amount. In S110, the focus sensitivity is read in the storage unit 1j. The focus sensitivity is a shift amount of the focus position when the focus lens group 1a is driven at a certain distance in the optical axis direction. In S111, the focus feed-out amount is calculated from the focus sensitivity and the defocus amount. Based on the calculated focus feed amount, driving is performed in S119, and one cycle of the automatic focus adjustment flow is completed.

  On the other hand, if it is determined in S107 that the reliability is low, the second diaphragm 1e is narrowed in S112. The F number of the second aperture stop 1e at this time is F0 (here, F / 8). This F0 is stored in the storage means 1j.

The F number F0 needs to be set appropriately to increase the contrast in order to improve the reliability. Therefore, it is desirable to satisfy the following expression, where δ is the diameter of the circle of confusion that is acceptable for obtaining the necessary contrast value, and D is the absolute value of the defocus end that should guarantee the operation of automatic focusing.
F0 ≧ D / δ (1)

In this reference example, for example, a 2/3 type CCD is used as the imaging surface phase difference sensor 1f, and δ is set to 0.020 mm corresponding to 4 pixels with respect to a pixel pitch of 0.005 mm. Further, D is set to 0.1 mm. Equation (1) is
F0 ≧ 5 (2)
Therefore, an F number larger than F / 5 is required.

On the other hand, in order not to reduce the accuracy of the phase difference calculation, it is necessary to appropriately set the F number F0 so that the Airy disk diameter does not become too large. Accordingly, it is desirable that the following equation is satisfied, where the F number threshold is F0, the sensitivity center wavelength of the imaging surface phase difference sensor 1f is λ, and the resolution ε is necessary to obtain the required calculation accuracy.
F0 ≦ ε / (1.22 × λ) (3)

In this reference example, for example, a 2/3 type CCD is used as the imaging surface phase difference sensor 1f, and the sensitivity center wavelength is set to 5.5 × 10 ⁻⁴ mm. Further, for a pixel pitch of 0.005 mm, ε is 0.020 mm corresponding to 4 pixels. Equation (3) is
F0 ≦ 30 (4)
Therefore, an F number smaller than F / 30 is required.

Summarizing the above formulas (1) and (3),
D / δ ≦ F0 ≦ ε / (1.22 × λ) (5)
Thus, by reducing the F number within a range that satisfies the expression (5), it is possible to achieve both improvement in reliability and desired calculation accuracy.

  FIG. 10 is a correspondence diagram between the automatic focusing area and the focusing light flux when the automatic focusing area 105 is off-axis in the present embodiment. FIG. 10A shows the position and optical path of the second stop 1e, FIG. 10B shows the automatic focus adjustment area 106, and FIG. 10C shows the light flux on the exit pupil 103 surface of the first stop 1b. Show. The second diaphragm 1e of the present invention has a mechanism capable of forming an opening asymmetrically with respect to the optical axis. The position where the formed opening is decentered is stored in advance in the storage unit 1 j as a table corresponding to the automatic focus adjustment area 106. In this table, the amount of eccentricity is set so that the light beam received by the pixel at the center of the automatic focus adjustment area is at the center of the exit pupil 103 surface.

  In subsequent S113, a correlation calculation is performed on the two reduced luminance signals, and a phase difference amount and a calculation reliability value are calculated. Since the second diaphragm 1e blocks the light beam, the base line length is read from the storage means 1j based on the F number of the second diaphragm. Subsequently, S115 to S117 are the same as S109 to S111, and the focus extension amount is calculated. In the flow from S108 when the second aperture stop 1e is opened, the drive is performed as it is according to the calculated focus feed amount. However, in the flow from S112 where the second aperture stop 1e is stopped, a step S118 is added. The This is because the lens generally has aberration, and the best focus position moves depending on the F number even at the same focus position. Since the flow from S108 is the same as the F-number on the imaging side, the focus position does not move. On the other hand, since the flow from S112 is different from the F-number of the optical system on the imaging side, processing for adding the correction amount to the focus drive amount (focus position) calculated in S118 is performed.

  FIG. 11 is a flow when the reliability value calculated by the correlation calculation in the state where the second diaphragm 1e is narrowed in S113 is lower than the threshold value. In S113-2, the F number of the second aperture stop 1e is further increased. In S113-3, after determining whether or not the light amount of the subject is below the threshold value, the correlation calculation is performed again in S113-4. If the reliability value exceeds the threshold value, the process returns to S114. If the reliability value is less than the threshold value, the process returns to S113-2. If the amount of light of the subject is insufficient, in step S113-6, the F number of the second aperture is decreased by 1/3 step to adjust the amount of light of the subject. Here, the 1/3 stage is used, but a 1/2 stage or 1 stage may be used.

  Further, in the flow shown in the present embodiment, automatic focus adjustment cannot be performed when the subject has a low contrast. Therefore, in order to perform automatic focus adjustment, when shooting a low-contrast subject, automatic focus adjustment may be performed by changing the threshold value of the reliability value. In order to determine that the subject is a low-contrast object, a step of comparing the contrast value of the luminance signal obtained by changing the F number of the second aperture is inserted. If the contrast value does not change even with different F-numbers, it can be determined that the subject has low contrast. In addition, by reducing the threshold value, it is possible to perform automatic focus adjustment even in a low contrast state.

  In this embodiment, the light beam is focused in a circular shape. However, the present invention is not limited to this, and may be a polygon such as a quadrangle or a hexagon. Furthermore, not only a mechanical aperture but also an aperture using a liquid crystal element or an electrochromic element may be used.

  As shown in the first embodiment, only the focus detection light beam can be focused without affecting the imaging light beam and regardless of the automatic focus adjustment area. Accordingly, it is possible to perform automatic focus adjustment that does not cause the detection accuracy to deteriorate or become undetectable even in a large defocus state. Further, it is possible to provide an automatic focusing lens device and an imaging system in which focusing accuracy does not deteriorate regardless of whether the automatic focusing area is on-axis or off-axis.

  FIG. 12 is a configuration diagram of the second embodiment. The configuration differs from the first embodiment in that it includes a zoom unit 1m, a focus lens position detection unit 1n, and a zoom position detection unit 1o. In addition, the storage means 1j stores the vignetting information in each pixel according to the zoom state, the focus state, and the F number, the threshold value for the difference in the amount of light in each photoelectric conversion unit, and the shift in the best focus position due to vignetting. Correction data.

  The vignetting is a phenomenon in which a part of the light beam is blocked by a lens frame or the like at a certain angle of view and the effective luminous flux is reduced. FIG. 13A shows the position and optical path of the second diaphragm 1e when vignetting occurs, and FIG. 13B shows the light flux on the exit pupil 103 surface of the first diaphragm 1b.

  FIG. 13B is a diagram showing that the light quantity balance in each photoelectric conversion unit of the imaging surface phase difference sensor 1f is lost due to vignetting. There are cases where a phase difference amount having a low reliability value is calculated at a predetermined screen position due to a loss of light amount balance, or phase difference detection is impossible.

  Therefore, in the present embodiment, in the case of zoom, focus, and F number where vignetting affects phase difference detection, the second diaphragm 1e is stopped to reduce the influence of vignetting. FIG. 14A shows the position and optical path of the second diaphragm 1e when vignetting occurs, and FIG. 14B shows the light flux on the exit pupil 103 surface of the first diaphragm 1b.

  Description will be made based on the flow of the present embodiment in FIG. The difference from the first embodiment is that S105 is changed to S205, S108 is changed to S208, S110 is changed to S210, S116 is changed to S216, and S118 is changed to S218. Also, S205-1 and S211-1 are inserted.

  In S205, the zoom / focus position is read in order to refer to vignetting information and focus sensitivity information. In addition, zoom focus. Read out vignetting information from F number / automatic focus adjustment area. In subsequent S205-1, a difference in light amount in each photoelectric conversion unit is compared with a threshold value. If the threshold value is not exceeded, the correlation calculation is performed in S106 while the second aperture stop 1e remains open. On the other hand, if the threshold value is exceeded, the second diaphragm 1e is squeezed in S112 so that vignetting has an F number that does not significantly affect the phase difference detection, and the correlation calculation is performed in S113. The threshold value is stored as a light amount difference that has a great influence on phase difference detection.

  In S208, since the baseline length changes due to minute vignetting, information on the zoom / focus position is required. Since the focus sensitivities in S210 and S216 differ depending on the zoom / focus position, the steps are different from those in the first embodiment.

  When vignetting occurs, the calculated focus feed amount does not achieve the best focus. For this reason, in S211-1 and S218, the focus is driven by referring to and taking into account the correction data for the shift of the best focus position due to vignetting from the storage means 1j.

  Similarly to the first embodiment, the flow in the case where the reliability value calculated by the correlation calculation in the state in which the second aperture 1e is reduced is lower than the threshold is not shown. The F number may be increased and the flow of S113 to S119 may be performed again. If the amount of light is insufficient when the second aperture stop 1e is stopped, a flow for decreasing the F number of the second aperture stop 1e may be performed.

  As shown in the second embodiment, in addition to the effects of the first embodiment, automatic focus adjustment suitable for a zoom lens having vignetting is possible.

  Although the outline of the configuration of the third embodiment is the same as that of the second embodiment, the present embodiment is characterized by the branching optical system 1c and the imaging plane phase difference sensor 1f. The branching optical system 1c branches only the light beam having the wavelength in the infrared region to the imaging surface phase difference sensor 1f, and branches the light beam having the wavelength in the visible light region on the imaging sensor 1d side. Further, since only the light beam in the infrared region is branched to the imaging surface phase difference sensor 1f side, the imaging surface phase difference sensor 1f has pixels having sensitivity in the infrared region as shown in FIG. However, it does not have a color filter or the like for controlling the wavelength transmission characteristics to be different. In addition, the storage unit 1j stores a correction value for a shift in the best focus position due to chromatic aberration in each zoom and focus state.

  FIG. 17 shows an automatic focusing flow. Compared with the second embodiment, steps S311-1 and 318 are different, and the shift of the best focus position due to chromatic aberration is corrected. This is because the lens generally has chromatic aberration, and the best focus position varies depending on the wavelength. In this embodiment, the imaging sensor 1d is acquired in RGB, while the imaging surface phase difference sensor 1f receives a light beam in the infrared region and performs automatic focus adjustment. When correction by chromatic aberration is not performed, the best focus position of the wavelength in the infrared region that is not received by the video signal. Therefore, the amount of shift in the best focus position due to chromatic aberration is corrected with respect to the focus drive amount calculated in S311-1 and 318, and automatic focus adjustment is performed in accordance with the imaging signal.

  In the third embodiment, in addition to the effects of the first and second embodiments, visible light is not reflected by the branching optical system 1c, so that the influence on the transmittance of visible light to the imaging sensor 1d is reduced.

  The configuration of the fourth embodiment is the same as that of the second embodiment, and the automatic focus adjustment flow is not changed. A difference from the second embodiment is a second diaphragm 1e. The second diaphragm 1e is composed of two members and is arranged as shown in FIG. The second aperture stop 1e is movable in the pupil division direction (horizontal direction) with respect to the pupil division direction (here horizontal direction) of the imaging plane phase difference sensor 1f, and the position of the opening in the pupil division direction and A mechanism for controlling the size is provided. FIG. 19A shows a state after driving the second diaphragm 1e when the automatic focusing area 105 is off-axis, and FIG. 19B shows automatic focusing on the exit pupil 103 surface of the first diaphragm 1b. FIG. 6 is a diagram showing a light beam passage region received by a central pixel of an area 105. The storage means 1j stores driving amounts of two members for an automatic focus adjustment area (coordinates in the pupil division direction (horizontal direction)), zoom, focus, and F number. The driving amount is stored so that the center of the aperture on the exit pupil 103 surface formed by the two stops coincides with the center of the light beam received by the central pixel in the automatic focus adjustment area. Further, the F number in the pupil division direction follows the equation (5) as in the first embodiment.

  In the first to third embodiments, at the time of large defocus, the same F number is controlled in the second diaphragm 1e in the pupil division direction and also in the direction perpendicular to the pupil division direction. However, the contrast value of the luminance signal in the two pupil division directions is greatly influenced by the F number of the light beam in the pupil division direction of each photoelectric conversion unit. In the present embodiment, the number of diaphragm members of the second diaphragm 1e is limited to two, and only a necessary light beam is controlled.

  As shown in the fourth embodiment described above, in addition to the effects of the first and second embodiments, the light amount can be effectively utilized when the second diaphragm 1e is driven. Further, the shape of the second aperture stop 1e can be achieved with a simple plate shape, and since the drive direction is one direction, it is possible to prevent a reduction in focusing accuracy due to the accuracy of the aperture member and the drive accuracy.

  The fifth embodiment is characterized by having two modes as an automatic focusing method. In the first mode, automatic focusing is performed only by automatic focusing using a phase difference signal. In the second mode, automatic focus adjustment using a contrast value of a video signal is performed after performing automatic focus adjustment using a phase difference signal.

  FIG. 20 is a block diagram of the fifth embodiment. The difference from the fourth embodiment is that a focusing mode switching means 1p is provided. The photographer can switch the focus mode by the focus mode switching means 1p. Further, the focusing mode may be automatically switched according to the shooting mode set by the photographer.

  FIG. 21 shows the focusing flow of this embodiment. As a difference from the second and fourth embodiments, a step of acquiring a focusing mode is inserted in S504. When the focusing mode is only the automatic focus adjustment based on the phase difference, that is, the first mode, the flow is not different from the flow in the second and fourth embodiments. In the case of the second mode, S505 for opening the second aperture stop 1e and S506 for performing automatic focus adjustment based on the contrast value of the video signal acquired by the imaging surface phase difference sensor 1f are inserted.

  The automatic focusing method using the contrast value in S506 will be briefly described. The focus lens group 1a is wobbled, and the position where the contrast value of the video signal in the automatic focus adjustment area 105 obtained by the imaging surface phase difference sensor 1f is the highest is detected. Automatic focus adjustment is performed based on the focus drive amount corresponding to the detected position.

  Here, an example of the focus lens group 1a is given as the group to be wobbled, but the present invention is not limited to this, and another lens group may be used. In particular, by wobbling a lens group disposed between the branching optical system 1c and the imaging surface phase difference sensor 1f, automatic focus adjustment based on a contrast value can be performed without affecting an image.

  Further, although not shown in the flow of the present embodiment, a flow of performing automatic focus adjustment using a contrast value after performing automatic focus adjustment by a plurality of phase differences may be used. In this case, the focus lens drive amount may be less than a predetermined threshold stored in advance.

  As shown in the fifth embodiment, in addition to the effects of the first, second, and fourth embodiments, the photographer can select whether or not to use the automatic focus adjustment using the contrast value. In the automatic focus adjustment using the contrast value, the focusing speed is slow, but the focusing accuracy is the highest. Therefore, in this embodiment, the photographer can freely select two types of focusing modes, the first mode giving priority to the focusing speed and the second mode giving priority to the accuracy, according to the shooting scene. Become.

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

101 Microlens 102a, b Photoelectric conversion unit 105 Automatic focus adjustment area 1a Focus lens 1b First aperture 1c Branching optical system 1d Imaging sensor 1e Second aperture 1f Imaging surface phase difference sensor 1g Focus lens control unit 1h Calculation unit 1l Automatic focus adjustment area acquisition means

Claims (11)

A focus lens group;
The first aperture,
A branching optical system for branching the light beam from the subject through the focus lens group and the first diaphragm into an imaging light beam and a focus detection light beam;
An imaging sensor for receiving the imaging luminous flux;
An imaging surface phase difference sensor that acquires a video signal and a phase difference signal from the light beam for focus detection;
A second diaphragm disposed between the branch optical system and the imaging surface phase difference sensor;
Means for acquiring a position for performing automatic focus adjustment in an image to be captured; and a focus state is acquired using a phase difference signal obtained from the imaging surface phase difference sensor, and the focus lens is based on the focus state. Control means for controlling the drive of the group and the second aperture;
Have
The control means controls an opening state of the second diaphragm based on information on a position where the automatic focus adjustment is performed.
A lens device.   The control means controls the aperture state of the second diaphragm so that the center of the light beam received by the pixel at the position where the automatic focus adjustment is performed passes through the center of the exit pupil plane of the first diaphragm. The lens device according to claim 1.   The control means obtains a phase difference amount and a reliability value of the calculation by calculation based on a signal obtained by the imaging surface phase difference sensor, and the second diaphragm based on the reliability value. The lens apparatus according to claim 1, wherein an opening state of the lens is controlled.   The lens apparatus according to claim 3, wherein the reliability value is a contrast of a signal obtained by the imaging surface phase difference sensor.   The control means determines a focus position of the focus lens group based on a focus state calculated based on a phase difference signal, an F number of an optical system for the imaging light flux by the first diaphragm, and the first diaphragm. 5. The lens apparatus according to claim 1, wherein correction is performed in accordance with a relationship between the F-number of the optical system with respect to the light beam for focus detection by the second diaphragm. .   The said 2nd aperture_diaphragm | restriction is comprised with two members movable in the direction which has a component of the pupil division direction of the said imaging surface phase difference sensor, The one of Claim 1 thru | or 5 characterized by the above-mentioned. The lens device described.   The control means forms an opening that is asymmetric with respect to the optical axis so that the center of the light beam received by the pixel at the position where the automatic focus adjustment is performed passes through the center of the exit pupil plane of the first diaphragm. The lens apparatus according to claim 1, wherein a driving amount of the second diaphragm is controlled.   The lens apparatus according to claim 1, wherein the number of openings formed by the second diaphragm is one.   The control means drives the focus lens group based on the phase difference signal obtained by the imaging surface phase difference sensor to adjust the focus, and then contrasts the video signal obtained by the imaging surface phase difference sensor. The lens apparatus according to claim 1, wherein focus adjustment for driving the focus lens group is performed using a value.   The control means sets the second diaphragm to an open state when performing automatic focus adjustment using a contrast value of a video signal obtained by the imaging surface phase difference sensor. Item 10. The lens device according to Item 9.   An imaging apparatus comprising: the lens apparatus according to claim 1; and a camera apparatus connected to the lens apparatus and having the imaging unit.

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