JP5025302B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus that acquires digital image data indicating a subject image by imaging.

  When capturing a subject image, focus control is generally performed in which a lens for forming the subject image on the image sensor is moved so that the subject image is formed at the position where the image sensor is disposed. ing.

  Focus control methods mainly include a method of detecting an imaging position where the contrast of an image indicated by digital image data acquired by imaging is maximized, and a subject image via a lens is divided into pupils and divided. And a method for detecting the phase difference of the subject image.

  As a technique using a method of detecting a phase difference, for example, as disclosed in Patent Document 1, a phase detection optical system is inserted into a photographing optical path, and a phase difference is detected by a photographing image sensor. Has been.

  Further, as in Patent Document 2 and Patent Document 3, it has been proposed to insert an optical path branching prism element into a photographing optical path and guide it to a focus detection sensor.

  Further, Patent Document 4 proposes that a split image prism is inserted in the optical path and focus detection is performed by image shift using an image sensor.

Japanese Patent Application Laid-Open No. H10-228561 describes that there is an opening for pupil division and the opening has a prism effect.
JP 2006-308926 A JP 2006-126652 A JP 2006-317918 A JP 2004-46132 A JP 2006-71950 A

  However, the techniques of Patent Documents 1 to 3 and Patent Document 5 have a problem that a sensor for detection is necessary.

  Further, the technique of Patent Document 4 requires a larger image than the split image prism, and if the shape of the image on the boundary line is not a straight line, it is determined that the image is out of focus even in the in-focus state. There was a problem that.

  Further, in the technique of Patent Document 1, an image is formed on the lens side of the original image plane and a lens for pupil division for phase detection is inserted, so that the distance between the photographing lens and the image plane is increased. It is possible.

  The present invention has been made to solve the above-described problems, and provides an imaging apparatus that can realize phase difference focusing control by splitting a light beam without causing an increase in the number of parts or an increase in optical path length. Objective.

In order to achieve the above object, the invention of claim 1 includes an optical system member for forming a subject image, and a changing means for driving the optical system member to change the imaging position of the subject image. An image pickup means for acquiring digital image data indicating a subject image via the optical system member, and an incident light from the optical system member that is divided into two by reflecting the incident light with respect to the optical axis at a predetermined reflection angle. a pair of first reflecting surface which is, each of the first has been a direction parallel to each of the optical axes of the optical arrangement the direction to the second of a pair of reflection of the image pickup means reflected by the reflecting surface A branching optical element formed by a prism plate having a reflecting surface, the optical path length from the optical member to the light receiving surface of the imaging means when the prism plate is interposed, and not through the prism plate The imaging means from the optical member in the case As the difference between the optical path length to the light receiving surface is canceled, the distance between the first reflecting surface and the second reflecting surface of the prism plate, and the refractive index of the prism plate is defined a plurality of branching optical element, by moving the plurality of branch optical element, a splitting optical device moving means to retractably between the optical member and the imaging means, the branch optical element moving means based on the plurality of branch optical elements into digital image data obtained by imaging by the imaging means in a state of being moved between the optical member and the imaging unit by being branched by the plurality of branch optical elements respectively of the incident light to derive the phase difference between the two images represented by the distance deriving means for deriving an object distance based on the derived result of each phase difference, respond to the subject distance derived by the distance deriving means And control means for controlling the changing means so that the subject image is imaged at the established position of the imaging means Te, provided between the optical member and the imaging means, the wavelength of light to be incident on said image pickup means Wavelength limiting means for limiting the distance, the wavelength limiting means, a distance deriving region used when deriving the subject distance by the distance deriving means, and after determining the position of the optical member, digital image data for photographing storage And a plurality of branch optical elements are provided in the distance deriving region of the wavelength limiting unit.

  According to the first aspect of the present invention, the optical system member for forming the subject image is driven to change the imaging position of the subject image, and the subject image obtained through the optical system member is shown. Digital image data is acquired by an imaging means.

Further, the branching optical element moving means divides the incident light from the optical system member between the optical system member and the image pickup means by dividing the incident light from the optical system member at a predetermined reflection angle with respect to the optical axis. A pair of first reflecting surfaces disposed on the first reflecting surface, and a pair of first reflecting surfaces reflecting light reflected by the first reflecting surfaces in a direction parallel to the optical axis and in a direction in which the imaging means is disposed. A branching optical element having two reflecting surfaces, and an optical path length from the optical member to the light receiving surface of the imaging means when the branching optical element is interposed, and not through the branching optical element The distance between the first reflecting surface and the second reflecting surface of the branch optical element so that the difference between the optical path length and the optical path length from the optical member to the light receiving surface of the imaging means is offset, and the refractive index of the prism plate is defined, the branch Branching by the branching optical element based on digital image data obtained by imaging by the imaging unit in a state where the branching optical element is moved between the optical system member and the imaging unit by a learning element moving unit The subject distance is derived based on the phase difference between the two images indicating the incident light, and the changing unit is controlled so that the subject image is formed at the position where the imaging unit is disposed according to the derived subject distance. Therefore, the phase difference focusing control can be realized by dividing the light beam without increasing the number of parts or increasing the optical path length.

  That is, in the present invention, a sensor such as an imaging device for detecting a phase difference is not required by providing a branchable optical element that can be projected and retracted between the optical member and the imaging means.

  In the present invention, the branching optical element includes the pair of first reflecting surfaces and the reflected light from the first reflecting surfaces in the optical axis direction of the light before branching in the arrangement direction of the imaging means. Since it comprises the second reflecting surface that reflects, the branch optical element can be realized in a compact manner.

The invention according to claim 1 includes a plurality of the branching optical elements, and the distance deriving unit derives a phase difference for each of the incident lights branched by the plurality of branching optical elements, and a result of deriving each phase difference. The subject distance may be derived based on the above.

The invention of claim 1, wherein, as in the invention according to claim 2, wherein, while changing the imaging position of the optical member by said changing means, based on digital image data obtained by imaging by the image pickup means The control further comprises a position specifying means for detecting an evaluation value indicating a high frequency component of luminance of the image and specifying the position of the optical member where the contrast of the read image is maximized based on the detected evaluation value. The means controls the changing means according to the subject distance derived by the distance deriving means, and then specifies the position of the optical member by the position specifying means and specifies the optical member by the changing means. It can also be configured to control to move to a different position.

According to a second aspect of the present invention, as in the third aspect of the present invention, there is further provided a determining unit that determines whether the position specifying unit can perform the position specification of the optical member satisfactorily or not. And the control means performs control of the changing means according to the subject distance derived by the distance deriving means, and then specifies the position of the optical member by the position specifying means and the optical member by the changing means. If the determination means determines that the position of the optical member cannot be satisfactorily executed, the subject distance by the distance deriving means is again determined. And the change unit may be controlled according to the derived subject distance.

The invention according to any one of claims 1 to 3 may be configured such that the wavelength is not restricted at the position where the branch optical element is disposed, as in the invention according to claim 4. Good.

The invention according to any one of claims 1 to 4 , as in the invention according to claim 5 , includes a display unit for displaying a subject image indicated by the digital image data, and the display unit includes the display unit. When displaying the subject image indicated by the digital image data obtained through the branching optical element, the two regions corresponding to the incident light divided by the branching optical element are combined, and the two regions The synthesized image may be displayed at the center of the image.

  As described above, according to the present invention, there is an excellent effect that the light flux can be divided and phase difference focusing control can be realized without causing an increase in the number of parts or an increase in the optical path length.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
(First embodiment)
First, an external configuration of the digital camera 10 according to the present embodiment will be described with reference to FIG.

  As shown in the figure, the front of the digital camera 10 is provided with a lens 12 for forming a subject image and a viewfinder 70 used for determining the composition of the subject to be photographed. On the top surface of the digital camera 10, a release button (so-called shutter) 56A that is pressed by a photographer when performing shooting and a power switch 56B are provided.

  Note that the release button 56A according to the present embodiment is in a state where it is pressed down to an intermediate position (hereinafter referred to as “half-pressed state”), and in a state where it is pressed down to a final pressed position that exceeds the intermediate position (hereinafter referred to as “herein”). It is configured to be able to detect a two-stage pressing operation of “fully pressed state”.

  In the digital camera 10 according to the present embodiment, the exposure state (shutter speed, aperture state) is set by operating the AE (Automatic Exposure) function by pressing the release button 56A halfway. After that, AF (Auto Focus) function is activated and focus control is performed, and then exposure (photographing) is performed when it is fully pressed.

  On the other hand, on the back of the digital camera 10, a liquid crystal display (hereinafter referred to as “the eyepiece” of the finder 70 and a subject image, various menu screens, messages, etc. indicated by the digital image data obtained by photographing). 30), a shooting mode that is a mode for performing shooting, and a playback mode that is a mode for displaying (reproducing) a subject image indicated by digital image data obtained by shooting on the LCD 30. A cross-cursor button 56D configured to include a mode selector switch 56C that is slid for setting, and four arrow keys that indicate four directions of movement in the display area of the LCD 30, up, down, left, and right; Is provided.

  Also, on the back of the digital camera 10, a menu key 56E that is pressed when displaying the main menu screen on the LCD 30, and an execution key 56F that is pressed when executing processing specified on the menu screen, A cancel key 56G that is pressed when various operations are canceled (cancelled) is provided.

  Next, the configuration of the electrical system of the digital camera 10 according to the present embodiment will be described with reference to FIG.

  As shown in the figure, the digital camera 10 includes an optical unit 13 including the lens 12 described above, a CCD 14 disposed behind the optical axis of the lens 12, and a correlated double sampling circuit (hereinafter “ CDS ”) 16 and an analog / digital converter (hereinafter referred to as“ ADC ”) 18 for converting the input analog signal into digital data, and the output terminal of the CCD 14 is the CDS 16. The output terminal of the CDS 16 is connected to the input terminal of the ADC 18.

  Here, the correlated double sampling processing by the CDS 16 is a feed included in the output signal for each pixel of the solid-state image sensor for the purpose of reducing noise (particularly thermal noise) included in the output signal of the solid-state image sensor. This is processing for obtaining accurate pixel data by taking the difference between the through component level and the pixel signal component level.

  On the other hand, the digital camera 10 has a line buffer having a predetermined capacity and an image input controller 20 that performs control for directly storing the input digital image data in a predetermined area of the second memory 40 described later, and the digital image data. An image signal processing circuit 22 that performs various image processing, a compression / decompression processing circuit 24 that performs compression processing on the digital image data in a predetermined compression format, and performs expansion processing on the compressed digital image data, and a digital image And a display control circuit 28 that generates a signal for causing the LCD 30 to display an image or a menu screen indicated by data and supplies the signal to the LCD 30. The input terminal of the image input controller 20 is connected to the output terminal of the ADC 18.

  In addition, the digital camera 10 includes a CPU (Central Processing Unit) 32 that controls the operation of the entire digital camera 10, an AF detection circuit 34 that detects a physical quantity required to operate the AF function, an AE function, and an AWB (Automatic). White Balance), an AE / AWB detection circuit 36 for detecting a physical quantity (in the present embodiment, an amount indicating the brightness of an image obtained by imaging by the CCD 14) required for operating the function, and various types of CPU 32. Consists of a first memory 38 configured by SDRAM (Synchronous Dynamic Random Access Memory) used as a work area at the time of execution of processing, and a VRAM (Video RAM) that mainly stores digital image data obtained by photographing. And a second memory 40.

  Furthermore, the digital camera 10 includes a media controller 42 for enabling the digital camera 10 to access a recording medium 42A configured by smart media (Smart Media (registered trademark)).

  Image input controller 20, image signal processing circuit 22, compression / decompression processing circuit 24, display control circuit 28, CPU 32, AF detection circuit 34, AE / AWB detection circuit 36, first memory 38, second memory 40, and medium The controllers 42 are connected to each other via a bus BUS.

  Therefore, the CPU 32 detects the operations of the image input controller 20, the image signal processing circuit 22, the compression / expansion processing circuit 24, and the display control circuit 28, and the AF detection circuit 34 and the AE / AWB detection circuit 36. Acquisition of the physical quantity, access to the first memory 38 and the second memory 40, and access to the recording medium 42A via the media controller 42 can be respectively performed.

  On the other hand, the digital camera 10 is provided with a timing generator 48 that mainly generates a timing signal for driving the CCD 14 and supplies the timing signal to the CCD 14. The timing generator 48 has an input terminal connected to the CPU 32 and an output terminal connected to the CCD 14, and the driving of the CCD 14 is controlled by the CPU 32 via the timing generator 48.

  Further, the operation unit 56 including the release button 56A, the power switch 56B, the mode changeover switch 56C, the cross cursor button 56D, the menu key 56E, the execution key 56F, and the cancel key 56G is connected to the CPU 32. The operation state for each of the operation units 56 can be always grasped.

  The digital camera 10 also includes an external device interface 64 that manages communication with a connected external device according to a predetermined interface standard (for example, USB (Universal Serial Bus) standard).

  The external device interface 64 is also connected to the bus BUS, and the CPU 32 can communicate with an external device 66 such as a PC or a printer connected to the external device interface 64.

  Further, the CPU 32 is connected to an input terminal of the motor drive unit 50, and an output terminal of the motor drive unit 50 is connected to a focus adjustment motor, a zoom motor, and an aperture drive motor provided in the optical unit 13.

  The lens 12 included in the optical unit 13 according to the present embodiment has a plurality of lenses, and is configured as a zoom lens that can change (magnify) the focal length, and includes a lens driving mechanism (not shown). Yes. The lens drive mechanism includes the focus adjustment motor, the zoom motor, and the aperture drive motor. The focus adjustment motor, the zoom motor, and the aperture drive motor are each supplied with a drive signal supplied from the motor drive unit 50 under the control of the CPU 32. Driven by.

  When changing the optical zoom magnification, the CPU 32 controls the zoom motor to change the focal length of the lens 12 included in the optical unit 13.

  Further, the CPU 32 performs focusing control by driving and controlling the focus adjustment motor so that the contrast of an image obtained by imaging by the CCD 14 is maximized. That is, in the digital camera 10 according to the present embodiment, as the focus control, the AF detection circuit 34 detects an evaluation value indicating a high-frequency component of the luminance of the image obtained by imaging by the CCD 14, and the detected evaluation value The contrast AF control by the so-called TTL (Through The Lens) method for setting the lens position so that the contrast of the read image is maximized can be executed.

  Further, in the present embodiment, the optical unit 13 is provided with a prism plate 84 (see FIG. 3) that divides the light beam incident on the CCD 14, and the AF detection circuit 34 performs imaging by the CCD 14 using the prism plate 84. TTL phase difference AF control that detects the phase difference between images indicated by the luminous flux divided based on the obtained image and derives the position of the lens that is in focus based on the phase difference is configured to be executable Has been.

  The CPU 32 designates an evaluation value when the contrast AF control is executed and a phase difference when the phase difference AF control is executed as a physical quantity detected by the AF detection circuit 34.

  As shown in FIG. 3, in the optical unit 13, an infrared cut glass 80 is disposed between the lens 12 and the CCD 14. The infrared cut glass 80 transmits light having a wavelength other than infrared light out of the light incident on the light receiving surface 14A of the CCD 14.

  As shown in the figure, a prism plate 84 can be inserted between the infrared cut glass 80 and the CCD 14.

  FIG. 4 is a front view of the CCD 14 as viewed from the light receiving surface 14A side. As shown in the figure, the prism plate 84 is supported by a support plate 82. The support plate 82 is rotated around the rotation shaft 82A by a prism moving motor (not shown) driven by a drive signal supplied from the motor drive unit 50 under the control of the CPU 32. As a result, the support plate 82 and the prism plate 84 are normally disposed at the positions indicated by chain lines in the figure, and at the positions indicated by solid lines in the figure at the time of TTL phase difference AF control.

  As shown in FIG. 5, the prism plate 84 includes a first reflecting surface 84A and a second reflecting surface 84B. The first reflecting surface 84A is provided in two surfaces so that the light beam incident on the prism plate 84 is divided into two at the center. The second reflecting surface 84 </ b> B causes the light divided and reflected by the first reflecting surface 84 </ b> A to enter the light receiving surface 14 </ b> A of the CCD 14.

  That is, as shown in the figure, when the light incident through the lens 12 forms an image on the light receiving surface 14A of the CCD 14, the light incident on the prism plate 84 is reduced to 2 by the two first reflecting surfaces. The light is divided, guided to the second reflecting surface, and incident on the light receiving surface 14 </ b> A of the CCD 14.

  Here, the optical path length of the light incident on the light receiving surface 14A via the prism plate 84 is longer than the optical path length of the light incident on the light receiving surface 14A without passing through the prism plate 84. Therefore, in the present embodiment, the refractive index of the prism plate 84 is set so that the difference in optical path length can be offset.

  Therefore, as shown in the figure, the optical path length when the prism plate 84 is interposed is longer than the optical path length when the prism plate 84 is not interposed, but the focal position is the same.

  Further, since the light incident on the prism plate 84 is divided and imaged at positions distant from each other, in the image captured by the CCD 14, for example, as shown in FIG. Occurs. In the figure, a region 87 shown in the central portion and its left and right regions 86A and 86B are images obtained through the prism plate 84. The region 87 is a shadow of the first reflecting surface 84A, and the left and right regions 86A and 86B are images indicated by the divided light beams.

  Here, at the time of out-of-focus, there is a phase difference between the image of the area 86A and the image of the area 86B, and by deriving the phase difference, it is possible to derive the position of the lens in the in-focus state.

  In the present embodiment, a description has been given of a mode in which the refractive index of the prism plate 84 is set so that the focal positions of the light beam transmitted through the prism plate 84 and the light beam not transmitted through the prism plate 84 completely coincide. However, the present invention is not limited to this.

  That is, when the focal position of the light beam transmitted through the prism plate 84 and the light beam not transmitted through the prism plate 84 are deviated, the two light beams branched by the prism plate 84 are taken into consideration. The position of the lens may be derived with the state where the phase difference of the image indicated by is a predetermined phase difference as the in-focus state.

  Next, the operation of the digital camera 10 according to the present embodiment will be described. First, the overall processing flow when the shooting mode is set will be briefly described.

  First, an image is picked up by the CCD 14 via the optical unit 13, and signals indicating the subject image are sequentially output from the CCD 14. The signals output from the CCD 14 are sequentially input to the CDS 16 and subjected to correlated double sampling processing, and then input to the ADC 18. The ADC 18 receives R (red), G (green), and B (input from the CDS 16. The blue signal is converted into 12-bit R, G, and B signals (digital image data) and output to the image input controller 20.

  The image input controller 20 accumulates digital image data sequentially input from the ADC 18 in a built-in line buffer and temporarily stores it in a predetermined area of the second memory 40.

  Digital image data stored in a predetermined area of the second memory 40 is read out by the image signal processing circuit 22 under the control of the CPU 32, and a digital gain corresponding to the physical quantity detected by the AE / AWB detection circuit 36 is added to these. In addition to white balance adjustment, gamma processing and sharpness processing are performed to generate 8-bit digital image data, and further YC signal processing is performed to obtain luminance signal Y and chroma signals Cr and Cb (hereinafter referred to as “YC signal”). And the YC signal is stored in an area different from the predetermined area of the second memory 40.

  The LCD 30 is configured so that it can display a moving image (through image) obtained by continuous imaging by the CCD 14 and can be used as a finder. In this way, the LCD 30 is used as a finder. The generated YC signal is sequentially output to the LCD 30 via the display control circuit 28. As a result, a through image is displayed on the LCD 30.

  Here, when the release button 56A is half-pressed by the user, after the AE function is activated and the exposure state is set as described above, the AF function is activated and focus control is performed, and then the fully-pressed state is continued. In this case, the YC signal stored in the second memory 40 at this time is compressed in a predetermined compression format by the compression / decompression processing circuit 24 and then recorded as an image file on the recording medium 42A.

  FIG. 7 is a flowchart showing the flow of processing of the shooting processing program executed by the CPU 32 of the digital camera 10 when the release button 56A is operated by the user in the state where the shooting mode is set. Hereinafter, the photographing process according to the present embodiment will be described with reference to FIG.

  First, in step 100, the prism plate 84 is inserted, and then the process proceeds to step 102 to detect the phase difference AF.

  The prism plate 84 is inserted by driving a prism moving motor (not shown) via the motor driving unit 50 to rotate the support plate 82 about the rotation shaft 82A.

  The detection of the phase difference AF is performed by deriving the phase difference between the image of the area 86A and the image of the area 86B. The areas 86A and 86B can be specified based on, for example, a preset insertion position of the prism plate 84 set in advance. Moreover, the derivation of the phase difference can be performed by comparing the values of the corresponding pixels in each region. Further, the position of the lens that is in focus is derived based on the derived phase difference and the current lens position.

  In the next step 104, the focus lens is moved according to the in-focus position derived according to the detected phase difference AF, and then the process proceeds to step 106.

  In step 106, the prism moving motor described above is driven to retract the prism plate 84 from the light receiving surface 14A, and then the process proceeds to step 108. In step 108, it is determined whether or not the release button 56A has been fully pressed. If the determination is affirmative, the process proceeds to step 110.

  In step 110, as a photographing operation, the YC signal stored in the second memory 40 at this time is compressed in a predetermined compression format by the compression / decompression processing circuit 24 and then recorded as an image file on the recording medium 42A. The main shooting process ends.

  On the other hand, if a negative determination is made in step 108, the process proceeds to step 112 to determine whether or not the release button 56A has been returned to the non-depressed position. If the determination is negative, the process again returns to step 108. Return. If the determination at step 112 is affirmative, the actual photographing process is terminated.

  As described above, according to the first embodiment, by providing the prism plate 84 that can be projected and retracted between the lens 12 and the light receiving surface 14A of the CCD 14, the CCD 14 also serves as an imaging device for detecting the phase difference AF. Therefore, it is not necessary to provide a separate sensor.

  In the first embodiment, the prism plate 84 includes a pair of first reflecting surfaces 84A, and the reflected light from each first reflecting surface 84A is in the optical axis direction of the light before branching, and the CCD 14 Since the second reflecting surface 84B that reflects in the direction of the light receiving surface 14A is used, the prism plate 84 can be made compact.

  Therefore, an increase in the optical path length can be prevented without increasing the optical system. In the present embodiment, the configuration in which one prism plate 84 is configured to be arranged at the center of the LCD 14 has been described. However, the present invention is not limited to this.

  For example, as shown in FIG. 8, a plurality of prism plates 84 may be attached to two support plates 82, respectively, so that they can be projected and retracted on the light receiving surface 14A. As a result, so-called multipoint ranging can also be executed.

  As a multi-point distance measurement method, a general method such as a method of performing weighting set in advance on a phase difference derived using each prism plate 84 or a method of selectively using one of them is used. it can.

The configuration in which the plurality of prism plates 84 are retracted is not limited to the two support plates 82, and may be retracted by one support plate 82 or three or more support plates 82.
(Second Embodiment)
In the first embodiment, the configuration in which the prism plate 84 is configured to be able to appear and retract on the light receiving surface 14A by the rotation operation of the support plate 82 has been described. However, in the second embodiment, the prism portion is integrated with the infrared cut glass. The form to form is demonstrated.

  Note that in the configuration of the digital camera of the second embodiment, the same reference numerals are given to the same configurations as those of the digital camera 10 of the first embodiment, and illustration and description thereof are omitted.

  FIG. 9 shows an infrared cut plate 280 according to the second embodiment. As shown in the figure, the infrared cut plate 280 has a plate shape larger than the area of the light receiving surface 14A of the CCD 14. The infrared cut plate 280 is slidably moved on the light receiving surface side of the LCD 14 by a prism moving motor (not shown) driven by a drive signal supplied from the motor drive unit 50 under the control of the CPU 32. It is moved to either a position A indicated by a solid line or a position B indicated by an alternate long and short dash line in FIG.

  Also, as shown in the figure, a prism portion 284 is formed at a position facing the predetermined position of the light receiving surface 14A when moved to the position A.

  The prism portion 284 needs to be provided so as to be located in a region not facing the light receiving surface 14A when the infrared cut plate 280 is slid to the position B.

  As shown in FIG. 10, the infrared cut plate 280 is configured by performing IR cut processing 280A on the light receiving surface 14A side. In addition, the infrared cut plate 280 is formed with a first reflection surface 284A and a second reflection surface 284B in a part thereof, and constitutes a prism portion 284.

  That is, as shown in the figure, when the light incident through the lens 12 is imaged on the light receiving surface 14A of the CCD 14, the light incident on the prism portion 284 is reduced to 2 by the two first reflecting surfaces. The light is divided, guided to the second reflecting surface, and incident on the light receiving surface 14 </ b> A of the CCD 14.

  In the second embodiment, as in the first embodiment, the refractive index between the first reflecting surface 284A and the second reflecting surface 284B of the prism portion 284 can be offset by the difference in optical path length. Is set. Therefore, as shown in the figure, the optical path length when the prism portion 284 is passed is longer than the optical path length when the prism portion 284 is not passed, but the focal position is the same.

  Note that the flow of the imaging process in the second embodiment is the same as that in the first embodiment except that the projecting and retracting of the prism unit 284 is performed by sliding the infrared cut plate 280. Omitted.

  As described above, according to the second embodiment, since the IR cut plate 280 is provided with the prism portion 284, the phase difference AF can be performed without increasing the number of components. In addition, as compared with the case where a plurality of support plates 82 are used, the number of movable parts is reduced, and control is also easy.

  In the second embodiment, the form in which the IR cut processing 284A is also performed on the light receiving surface 14A side of the prism portion 284 has been described, but the present invention is not limited to this.

  For example, as shown in FIG. 11, the IR cut processing 284 may not be applied to the light emission region reflected by the second reflecting surface 284 </ b> B of the prism portion 284. In this case, since the infrared component of the light incident from the lens 12 is also transmitted through the prism unit 284, the amount of light incident on the light receiving surface 14A is increased, and it is efficient even at low luminance such as when shooting in a dark place. The phase difference AF can be detected.

  Since the IR cut processing 284 is applied to the portion of the infrared cut plate 280 except for the prism portion 284, the image obtained by photographing does not have the influence of redness due to infrared light.

In the second embodiment, the form in which the infrared cut plate 280 is provided with the plurality of prism parts 284 has been described. However, the present invention is not limited to this, and the form in which one prism part 284 is provided. You can also.
(Third embodiment)
Here, in each of the above embodiments, the shadow of the prism plate 84 or the prism portion 284 is reflected in the region 87 facing the prism plate 84 or the prism portion 284 in the through image during detection of the phase difference AF. The images corresponding to the light divided by the prism plate 84 or the prism portion 284 are respectively displayed on the left and right of the region 87 (see FIG. 6). That is, the image that should originally be displayed in the area 87 is displayed in the areas 86A and 86B.

  Therefore, in the third embodiment, a combined image obtained by combining the images corresponding to the light divided by the prism plate 84 or the prism unit 284 (the images of the two regions 56A and 56B) is displayed in the region 87. . Thereby, an image like a split image is displayed in the area 87.

  FIG. 12A shows a state where a composite image at the time of out-of-focus is displayed. When the focus position is not correct, the image of the area 86A and the image of the area 86B have different subject positions. For this reason, as shown in the figure, the contours of the subject in the combined image do not match.

  It should be noted that in the areas 56A and 56B, preset alternative images are displayed that indicate that the through image is different from the photographed image by inserting the prism plate 84 or the prism portion 284. In the example shown in the figure, a black-filled image is displayed as a preset substitute image.

  FIG. 12B shows a state where a composite image at the time of focusing is displayed. When the focal positions are in agreement, there is no phase difference between the image of the area 86A and the image of the area 86B, and the positions of the subjects coincide. Therefore, as shown in the figure, an image in which the contour of the subject in the combined image matches is displayed.

  Thereby, it becomes easy for the user to check the in-focus position and the in-focus state.

  The positions of the areas 86A and 86B and the area 87 may be extracted based on the image data, or an image of an area set in advance according to the insertion position of the prism plate 84 or the prism unit 284 is extracted. You may make it do.

  Further, the display control unit circuit 28 can perform extraction, synthesis, and fitting of the synthesized image into the area 87 and display of the substitute image in the area 86A and the area 86B.

  As described above, according to the third embodiment, since the display is like a split image, the user can easily confirm the in-focus point and the in-focus state.

  Note that the flow of the imaging process described in the above embodiment (see FIG. 7) is an example, and it is needless to say that it can be changed as appropriate without departing from the gist of the present invention.

That is, in each of the above-described embodiments, the phase difference AF is once detected and then the prism plate 84 is retracted, and then the photographing operation is performed after the release button 56A is fully pressed. However, the present invention is not limited to this.
(Modification 1)
For example, the phase difference AF may be detected and the focus lens may be moved based on the detection of the phase difference AF while the prism plate 84 remains inserted until the release button 56A is fully pressed.

  FIG. 13 shows a flow of imaging processing according to the first modification. Hereinafter, the photographing process according to the first modification will be described with reference to FIG.

  In the first modification, as an example, a case where the present invention is applied to the digital camera 10 having the configuration using the prism plate 84 described in the first embodiment will be described. Therefore, as described in the second embodiment, the present invention may be applied to the digital camera 10 having a configuration in which the prism portion 284 is provided on the infrared cut plate 280. In the configuration of the first embodiment or the second embodiment, Needless to say, the present invention may be applied to the digital camera 10 that executes the composition / inset processing of the third embodiment.

  First, in step 130, the prism plate 84 is inserted, and then, the process proceeds to step 132 to detect the phase difference AF.

  The prism plate 84 is inserted by driving a prism moving motor (not shown) via the motor driving unit 50 to rotate the support plate 82 about the rotation shaft 82A.

  The detection of the phase difference AF is performed by deriving the phase difference between the image of the area 86A and the image of the area 86B. The areas 86A and 86B can be specified based on, for example, a preset insertion position of the prism plate 84 set in advance. Moreover, the derivation of the phase difference can be performed by comparing the values of the corresponding pixels in each region. Further, the position of the lens that is in focus is derived based on the derived phase difference and the current lens position.

  In the next step 134, the focus lens is moved according to the in-focus position derived in accordance with the detected phase difference AF, and then the process proceeds to step 136.

  In step 136, it is determined whether or not the release button 56A is fully pressed. If the determination is affirmative, the process proceeds to step 138.

  In step 138, the prism moving motor described above is driven to retract the prism plate 84 from the light receiving surface 14A, and then the process proceeds to step 140.

  In step 140, as a photographing operation, the YC signal stored in the second memory 40 at this time is compressed in a predetermined compression format by the compression / decompression processing circuit 24 and then recorded as an image file on the recording medium 42A. The main shooting process ends.

  On the other hand, when a negative determination is made at step 136, the routine proceeds to step 142, where it is determined whether or not the release button 56A has been returned to the non-depressed position. Return.

  If the determination in step 142 is affirmative, the process proceeds to step 144 to drive the prism moving motor described above to retract the prism plate 84 from the light receiving surface 14A, and then the main photographing process is terminated.

According to the first modification, the focused state can be continuously maintained until the photographing operation is performed.
(Modification 2)
Further, for example, focusing control based on detection of phase difference AF and focusing control based on detection of contrast AF may be used in combination.

  FIG. 14 shows a flow of photographing processing according to the second modification. Hereinafter, the photographing process according to Modification 2 will be described with reference to FIG.

  In the second modification, as an example, a case where the present invention is applied to the digital camera 10 having the configuration using the prism plate 84 described in the first embodiment will be described. Therefore, as described in the second embodiment, the present invention may be applied to the digital camera 10 having a configuration in which the prism portion 284 is provided on the infrared cut plate 280. In the configuration of the first embodiment or the second embodiment, Needless to say, the present invention may be applied to the digital camera 10 that executes the composition / inset processing of the third embodiment.

  First, in step 150, the prism plate 84 is inserted, and then the process proceeds to step 152 to detect the phase difference AF.

  The prism plate 84 is inserted by driving a prism moving motor (not shown) via the motor driving unit 50 to rotate the support plate 82 about the rotation shaft 82A.

  The detection of the phase difference AF is performed by deriving the phase difference between the image of the area 86A and the image of the area 86B. The areas 86A and 86B can be specified based on, for example, a preset insertion position of the prism plate 84 set in advance. Moreover, the derivation of the phase difference can be performed by comparing the values of the corresponding pixels in each region. Further, the position of the lens that is in focus is derived based on the derived phase difference and the current lens position.

  In the next step 154, the focus lens is moved in accordance with the in-focus position derived in accordance with the detected phase difference AF, and then the process proceeds to step 156.

  In step 156, the prism moving motor described above is driven to retract the prism plate 84 from the light receiving surface 14A, and then the process proceeds to step 158.

  In step 158, focusing control based on detection of contrast AF is executed, and thereafter, the process proceeds to step 160.

  Note that the focus control based on the detection of contrast AF in step 158 executes the detection of contrast AF while moving the focus lens within a preset range around the position of the focus lens after the processing in step 154 above. The focus lens is moved to a position where the contrast is maximized.

  Note that the preset range is set narrower than the movable range of the focus lens. The wider the movable range, the better the focus control tends to be executed, while the time required for the focus control increases. Further, as the movable range is set narrower, the time required for focusing control is shortened. However, when there is a sudden change in the distance to the subject, the focusing control may not be performed well.

  In step 160, it is determined whether or not the release button 56A is fully pressed. If the determination is affirmative, the process proceeds to step 162.

  In step 162, as a photographing operation, the YC signal stored in the second memory 40 at this time is compressed in a predetermined compression format by the compression / decompression processing circuit 24 and then recorded as an image file on the recording medium 42A. The main shooting process ends.

  On the other hand, if a negative determination is made in step 160, the process proceeds to step 164 to determine whether or not the release button 56A has been returned to the non-pressed position. If the determination is negative, the process returns to step 158 again. Return.

  If the determination at step 164 is affirmative, the actual photographing process is terminated.

According to the second modification, since the focusing state is quickly achieved by the phase difference AF control using the prism plate 84, and then the contrast AF control is executed, the focusing is continuously performed while suppressing the movement of the prism to the through image. It can be in a focused state.
(Modification 3)
Further, when the focus control based on the detection of the phase difference AF and the focus control based on the detection of the contrast AF are used in combination, any focus control can be prioritized according to the situation at the time of shooting.

  FIG. 15 shows a flow of imaging processing according to the third modification. Hereinafter, the photographing process according to Modification 3 will be described with reference to FIG.

  In the third modification, as an example, a case where the present invention is applied to the digital camera 10 having the configuration using the prism plate 84 described in the first embodiment will be described. Therefore, as described in the second embodiment, the present invention may be applied to the digital camera 10 having a configuration in which the prism portion 284 is provided on the infrared cut plate 280. In the configuration of the first embodiment or the second embodiment, Needless to say, the present invention may be applied to the digital camera 10 that executes the composition / inset processing of the third embodiment.

  First, in step 170, the prism plate 84 is inserted, and then the process proceeds to step 172 to detect the phase difference AF.

  The prism plate 84 is inserted by driving a prism moving motor (not shown) via the motor driving unit 50 to rotate the support plate 82 about the rotation shaft 82A.

  The detection of the phase difference AF is performed by deriving the phase difference between the image of the area 86A and the image of the area 86B. The areas 86A and 86B can be specified based on, for example, a preset insertion position of the prism plate 84 set in advance. Moreover, the derivation of the phase difference can be performed by comparing the values of the corresponding pixels in each region. Further, the position of the lens that is in focus is derived based on the derived phase difference and the current lens position.

  In the next step 174, the focus lens is moved according to the in-focus position derived according to the detected phase difference AF, and then the process proceeds to step 176.

  In step 176, focusing control is performed by detecting contrast AF, and then the process proceeds to step 178.

  The focus control based on the detection of contrast AF in step 176 executes the detection of contrast AF while moving the focus lens within a preset range around the position of the focus lens after the processing in step 174. The focus lens is moved to a position where the contrast is maximized.

  Note that the preset range is set narrower than the movable range of the focus lens. The wider the movable range, the better the focus control tends to be executed, while the time required for the focus control increases. Further, as the movable range is set narrower, the time required for focusing control is shortened. However, when there is a sudden change in the distance to the subject, the focusing control may not be performed well.

  Therefore, in step 178, it is determined whether or not the focus control by contrast AF has been successfully performed. If the determination is negative, the process returns to step 172 again, and the focus control by phase difference AF detection is performed again. I am trying to do it.

The determination as to whether or not the focusing control has been successfully performed can be made based on, for example, the contrast AF evaluation value. Hereinafter, a case where the detection of contrast AF cannot be performed satisfactorily will be described. That is, in the case of the following example, it is preferable to execute rapid focusing control by phase difference AF again.
(1) When the amount of change in the contrast AF evaluation value exceeds a certain threshold value The amount of change in the evaluation value when the contrast AF control is executed a plurality of times is derived, and if the amount of change is large, The distance may have changed significantly. In addition, it can be considered that the distance to the subject may further change in the future.
(2) When the contrast AF evaluation value is less than or equal to a certain threshold value When the contrast AF evaluation value is less than a predetermined threshold value, there is a possibility that the lens position is far from the in-focus position. In this case, it can be considered that the distance to the subject has changed greatly.
(3) When a movement vector is calculated based on the detection distance by contrast AF, and the magnitude of the vector exceeds a certain threshold, by calculating the movement vector, it is outside the range in which the lens is moved depending on the calculated vector size. It can be estimated whether or not there is a possibility that the contrast AF evaluation value is maximized.

  In step 178, determination may be made by applying any one of (1) to (3), and if one or more combinations are applied, it can be performed satisfactorily. It may be determined that there was not.

  On the other hand, if the determination in step 178 is affirmative, the process proceeds to step 180.

  In step 180, it is determined whether or not the release button 56A is fully pressed. If the determination is affirmative, the process proceeds to step 182.

  In step 182, the prism moving motor described above is driven to retract the prism plate 84 from the light receiving surface 14 </ b> A, and then the process proceeds to step 184.

  In step 184, as a photographing operation, the YC signal stored in the second memory 40 at this time is compressed in a predetermined compression format by the compression / decompression processing circuit 24 and then recorded as an image file on the recording medium 42A. The main shooting process ends.

  On the other hand, if a negative determination is made in step 180, the process proceeds to step 186 to determine whether or not the release button 56A has been returned to the non-depressed position. If the determination is negative, the process returns to step 176 again. Return.

  If the determination in step 186 is affirmative, the process proceeds to step 188 where the prism moving motor described above is driven to retract the prism plate 84 from the light receiving surface 14A, and then the main photographing process is terminated.

  According to the third modification, since the focusing state is quickly achieved by the phase difference AF control using the prism plate 84 and then the contrast AF control is executed, the focusing is continuously performed while suppressing the movement of the prism to the through image. It can be in a focused state. Further, when the subject has moved greatly, the phase difference AF control is executed again, so that the focused state can be quickly achieved.

  Note that the configuration of the digital camera 10 described in the above embodiments (see FIGS. 1 and 2) is merely an example, and it is needless to say that the configuration can be appropriately changed without departing from the gist of the present invention.

  For example, when the contrast AF control is not executed in the photographing process (see FIGS. 7 and 13), the AF detection circuit 34 can be configured to detect only the phase difference.

It is an external view which shows the external appearance of the digital camera which concerns on embodiment. It is a block diagram which shows the structure of the electric system of the digital camera which concerns on embodiment. It is a side view which shows the state which inserted the prism board which concerns on 1st Embodiment in the imaging | photography optical path. It is a front view which shows the positional relationship of the prism plate which concerns on 1st Embodiment, and the light-receiving surface of CCD. It is sectional drawing explaining the division | segmentation state of the light beam by the prism plate which concerns on 1st Embodiment. It is a schematic diagram which shows an example of the image obtained when a prism board is inserted and it images. It is a flowchart which shows the flow of the imaging | photography process which concerns on 1st Embodiment. It is a front view which shows an example of the form which provides a some prism board. It is a front view which shows the positional relationship of the infrared cut plate provided with the prism part which concerns on 2nd Embodiment, and the light-receiving surface of CCD. It is sectional drawing of the infrared cut plate which concerns on 2nd Embodiment. It is sectional drawing of the infrared cut plate of another form. It is a schematic diagram which shows an example of the image displayed on LCD at the time of execution of the imaging | photography process which concerns on 3rd Embodiment. 10 is a flowchart illustrating a flow of imaging processing according to Modification Example 1. 10 is a flowchart illustrating a flow of imaging processing according to Modification Example 2. 14 is a flowchart showing a flow of imaging processing according to Modification 3.

Explanation of symbols

10 Digital Camera 12 Lens 13 Optical Unit (Optical System Member)
14 CCD (imaging means)
30 LCD (display means)
32 CPU (distance deriving means, control means, position specifying means, determination means)
34 AF detection circuit (distance deriving means, position specifying means)
42A Recording media (recording media)
50 Motor drive unit (changing means, branching optical element moving means)
56 Operation unit (input means)
84 Prism plate (branching optical element)
280 Infrared cut glass (wavelength limiting means)
284 Prism (branching optical element)

Claims (5)

An optical member for forming a subject image;
Changing means for driving the optical system member to change the imaging position of the subject image;
Imaging means for acquiring digital image data representing a subject image via the optical system member;
The incident light from the optical system member is reflected by a pair of first reflecting surfaces arranged so as to be divided into two by reflecting the incident light with respect to the optical axis at a predetermined reflection angle, and reflected by the first reflecting surfaces. a branched optical element made of a prism plate having a second reflecting surface of a pair of reflection at the arrangement direction of the imaging means in a direction parallel to the light each of said optical axis, the said The difference between the optical path length from the optical member through the prism plate to the light receiving surface of the imaging unit and the optical path length from the optical member to the light receiving surface of the imaging unit without the prism plate cancels each other. A plurality of branch optical elements in which a distance between the first reflecting surface and the second reflecting surface of the prism plate and a refractive index of the prism plate are determined;
By moving the plurality of branch optical element, a splitting optical device moving means to retractably between the optical member and the image pickup means,
Based on digital image data obtained by imaging by the imaging means in a state where the plurality of branching optical elements are moved between the optical system member and the imaging means by the branching optical element moving means , A distance deriving unit for deriving a phase difference between two images represented by each of incident light branched by the branching optical element, and deriving a subject distance based on a result of deriving each phase difference ;
Control means for controlling the changing means so that a subject image is formed at an arrangement position of the imaging means according to the subject distance derived by the distance deriving means;
A wavelength limiting unit that is provided between the imaging unit and the optical member and limits a wavelength of light incident on the imaging unit;
With
The wavelength limiting unit includes a distance deriving region used when deriving a subject distance by the distance deriving unit, and a photographing region used when acquiring digital image data for photographing storage after determining the position of the optical member. ,
An imaging apparatus in which the plurality of branch optical elements are provided in the distance deriving region of the wavelength limiting unit . While changing the imaging position by the optical member by the changing means, an evaluation value indicating a high frequency component of the luminance of the image based on the digital image data acquired by imaging by the imaging means is detected, and the detected evaluation value is Based on a position specifying means for specifying the position of the optical member where the contrast of the read image is maximized,
The control means performs control of the changing means according to the subject distance derived by the distance deriving means, and then specifies the position of the optical member by the position specifying means and the optical member by the changing means. The imaging device according to claim 1 , wherein the imaging device is controlled to move to a specified position. A determination means for determining whether or not the position of the optical member by the position specifying means has been successfully executed or not.
The control means performs control of the changing means according to the subject distance derived by the distance deriving means, and then specifies the position of the optical member by the position specifying means and the optical member by the changing means. Control is performed so as to move to the specified position, and if the determination unit determines that the position of the optical member has not been satisfactorily executed, the subject distance is derived again by the distance deriving unit. The imaging apparatus according to claim 2 , wherein control is performed so that the change unit is controlled according to the derived subject distance. The imaging apparatus according to any one of claims 1 to 3 , wherein the wavelength is not restricted at an arrangement position of the branch optical element. Display means for displaying a subject image indicated by the digital image data;
When displaying the subject image indicated by the digital image data obtained through the branch optical element on the display means, the images of the two regions corresponding to the incident light divided by the branch optical element are synthesized. the imaging apparatus according to any one of claims 1 to 4 for displaying the synthesized image in the center of the two regions.

Images