JP2009086429A - Imaging apparatus and imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of quickly detecting the focal position in an imaging surface of a subject image, and to provide an imaging method. <P>SOLUTION: The imaging apparatus includes optical elements 110 and 112 in which the incident surface of light is arranged on an optical path from a subject to the imaging surface and which has an electro-optic effect, so that a refractive index distribution where the refractive index is gradually increased or decreased from one end in a surface direction of the incident surface to the other end by the application of a voltage is formed and transmits the image of the subject toward the imaging surface. Further, the imaging apparatus includes: an image sensor which is arranged on the imaging surface where the light from the subject after passing through the optical element is imaged and converts the light into an electric signal by photoelectric conversion; an image shift position detecting section which detects the shift position of the subject image on the imaging surface caused by refraction in the optical element, based on the electric signal; a focus lens driving control section which focuses the subject image on the imaging surface by movement in an optical axis direction; and a driving position calculating section which calculates the driving position of a focus lens, based on the detected shift position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus and an imaging method.

  For example, in an imaging device such as a single-lens reflex camera or compact camera, as a method of adjusting the focus position, an auto-focus method in which the imaging device automatically detects the focus position and drives the focus lens, and the user confirms the viewfinder and the screen. There is a manual focus method to adjust the focus position.

  In the manual focus method, for example, a subject can be confirmed by enlarging and displaying the subject in the live view display displayed on the screen. On the other hand, the autofocus method includes a phase difference detection method and a contrast detection (video autofocus) method. The phase difference detection method is generally used in a single-lens reflex camera, and detects a focus position by detecting an image shift amount of a split image of a subject image generated by a prism arranged on a light incident side of an image sensor. The contrast detection method is generally used in compact cameras, acquires image information while moving the focus lens, detects the position with the highest contrast (the position where the most edges are detected), and determines that position as the focus position. To do.

  Patent Document 1 discloses a technique for generating a split image by disposing a liquid crystal diffraction grating on the light incident side of an imaging device.

JP 2006-154506 A

  However, even if the subject image is magnified and displayed by the manual focus method, when the image pickup apparatus is held by hand, the subject image is displayed with the camera shake amplified, which may make it difficult to confirm the focus. In addition, there is a problem that even if the focus lens is operated in an enlarged display, the blur change is small and it is difficult to visually confirm, so that it is impossible to focus quickly.

  Further, when the contrast detection method is used in the autofocus method, it is necessary to detect the focus position by driving the focus lens so-called hill-climbing, so that it takes time until the focus position is determined. For this reason, the autofocus of a compact camera in which a contrast detection method is often used is generally time-consuming. In addition, in the compact camera, there is no space for arranging the prism on the optical path, so it is difficult to apply the phase difference detection method.

  On the other hand, if a liquid crystal diffraction grating is used as in Patent Document 1, the phase difference detection method can be adopted in a space-saving manner. It was. In addition, the liquid crystal diffraction grating disclosed in Patent Document 1 has a constant refractive index because a layered structure in which high-density layers and low-density layers of liquid crystal particles are alternately arranged is fixed at a certain angle. is there. Therefore, when the lens aperture is larger than a predetermined aperture value determined by the refractive index of the diffraction grating, there is a problem that vignetting occurs and the split image becomes dark.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a new and improved technique capable of quickly detecting the in-focus position of the subject image on the imaging surface. An imaging device and an imaging method are provided.

  In order to solve the above-described problem, according to an aspect of the present invention, an incident surface of light is disposed on an optical path from a subject to an imaging surface, and has an electro-optic effect so that the surface of the incident surface can be changed by voltage application. An imaging apparatus is provided that includes an optical element that forms a refractive index distribution in which a refractive index gradually increases or decreases from one end to the other end and transmits an image of a subject toward an imaging surface.

  An imaging device that is disposed on an imaging surface on which light from a subject that has passed through the optical element forms an image, converts the light into an electrical signal by photoelectric conversion, and an imaging surface that is generated by refraction at the optical element based on the electrical signal An image shift position detection unit that detects a shift position of the subject image, and a focus lens drive control unit that controls driving of a focus lens that focuses the subject image on the imaging surface by moving in the optical axis direction. And a drive position calculation unit that calculates the drive position of the focus lens based on the misalignment position.

  An image sensor that is arranged on the imaging surface where light from the subject forms an image, converts the light into an electrical signal by photoelectric conversion, and an object image on the imaging surface when no voltage is applied based on the electrical signal. An image processing unit that combines the first image and the second image generated by the subject image on the imaging surface when voltage is applied, and the combined image synthesized by the image processing unit in the image display unit An image display control unit to be displayed may be provided.

  The image processing unit may synthesize the first image and the second image by moving a relative position of a plurality of regions in the second image by a predetermined amount.

  The polarity of the voltage applied to the optical element based on the relationship between the movement direction of the focus lens that focuses the subject image on the imaging surface by moving in the optical axis direction and the manual operation direction for moving the focus lens There may be provided a voltage polarity control section for changing the voltage.

  An aperture value acquisition unit that acquires an aperture value of a lens that forms a subject image on the imaging surface, and a voltage value control unit that changes a voltage value applied to the optical element based on the acquired aperture value. The optical element may change the refractive index according to the voltage value.

  Of the image formed on the imaging surface through the optical element, a predetermined correction process may be performed on the image corresponding to the end of the optical element.

  In order to solve the above-described problem, according to another aspect of the present invention, an optical element in which a light incident surface is arranged on an optical path from a subject to an imaging surface has an electro-optic effect to apply voltage. And a step of forming a refractive index distribution in which the refractive index gradually increases or decreases from one end to the other end in the surface direction of the incident surface, and an imaging element disposed on an imaging surface on which light from a subject transmitted through the optical element is imaged A step of converting light into an electric signal by photoelectric conversion, a step of detecting a shift position of a subject image on an imaging surface caused by refraction by an optical element based on the electric signal, and a movement in an optical axis direction Including a step of controlling driving of the focus lens for focusing the subject image on the imaging surface, and a step of calculating a driving position of the focus lens based on the detected shift position. Imaging wherein the door is provided.

  According to the present invention, the in-focus position of the subject image on the imaging surface can be quickly detected.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(Configuration of the first embodiment)
First, the configuration of the imaging apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating an imaging apparatus according to the present embodiment. As shown in FIG. 1, the imaging apparatus 100 according to the present embodiment includes an imaging optical system 102, a CCD 104, a motor driving unit 106, a serial I / F 108, an AFE (analog front end) 120, a card I / O. F130, video I / F132, key I / F134, operation key 135, compression processing unit 150, image processing unit 152, SDRAM 160, MPU 170, and the like.

  The imaging apparatus 100 according to the present embodiment includes an imaging optical system 102 on the front surface of the CCD 104. The imaging optical system 102 is an optical system that images external light information on the CCD 104. For example, a lens (not shown), a zoom mechanism (not shown), and a focus mechanism (including a focus lens). (Not shown), a diaphragm mechanism (not shown) that can limit the direction and range of the light flux by changing the size of the aperture, and a cylindrical lens barrel (not shown) to which the lens is attached. ing.

  The CCD 104 is composed of an element capable of photoelectric conversion that converts optical information incident via the imaging optical system 102 into an electric signal, and each element generates an electric signal corresponding to the received light. In the present embodiment, the case where the CCD 104 is applied as an example of the image pickup device has been described. However, the present invention is not limited to this example. For example, a complementary metal oxide semiconductor (CMOS) can be applied.

  In order to control the exposure time of the CCD 104, a mechanical shutter (not shown) can be applied so that the light is blocked during non-photographing and the light is applied only during photographing. Further, the present invention is not limited to this, and an electronic shutter (not shown) may be applied. Note that the operation of the mechanical shutter or the electronic shutter is performed by a shutter button which is one of the operation keys 135.

  The motor driving unit 106 drives, for example, a zoom mechanism, a focus mechanism, and a diaphragm mechanism of the imaging optical system 102. The motor drive unit 106 receives an operation signal from the MPU 170 or the like via the serial I / F 108.

  The AFE 120 includes, for example, an AGC (automatic gain control) 122, an A / D converter 124, a timing generator 126, and the like. The AFE 120 receives an operation signal from the MPU 170 or the like via the serial I / F 108. The AGC 122 includes a correlated double sampling circuit and an amplifier, and removes low frequency noise included in the electrical signal output from the CCD 104 and amplifies the electrical signal to an arbitrary level.

  The A / D conversion unit 124 digitally converts the electrical signal output from the AGC 122 to generate a digital signal. The A / D conversion unit 124 outputs the generated digital signal to the image processing unit 152 and the like.

  The timing generator 126 inputs a timing signal to the CCD 104 and the AGC 122, and controls the exposure period of each pixel constituting the CCD 104 and the charge readout control. The timing generator 126 has a synchronization signal generator, and the imaging device operates based on the synchronization signal.

  The card I / F 130 controls writing of image data to the memory card 131 or reading of image data and setting information recorded on the memory card 131. The memory card 131 is a semiconductor storage medium or the like, and records captured image data. For example, a storage medium such as an optical recording medium (CD, DVD, etc.), a magneto-optical disk, or a magnetic disk may be used. The card I / F 130 and the memory card 131 may be configured to be detachable from the imaging device 100.

  The image display unit 133 is driven and controlled by the video I / F 132. The image display unit 133 includes display means such as an LCD (Liquid Crystal Display). The image display unit 133 performs live view display before performing an imaging operation read from the VRAM, various setting screens of the imaging apparatus 100, and display of images captured and recorded. The image display unit 133 displays the synthesized image synthesized by the image processing unit 152. The VRAM is a memory for image display, and is composed of a memory having a plurality of channels so that writing of a display image and display on the image display unit 133 can be performed simultaneously. The VRAM temporarily stores an image signal in live view display on the image display unit 133 during recording and display on the image display unit 133 during playback.

  The operation key 135 is used to perform various settings and operations on the imaging apparatus 100, and the input operation is output as a signal to the MPU 170 through the key I / F 134.

  The compression processing unit 150 converts input image data composed of a digital signal into data compressed in a compression format such as a JPEG compression format. The image processing unit 152 performs processing on the digital signal output from the A / D conversion unit 124 or the image on the SDRAM 160 and outputs the image to the SDRAM 160.

  An SDRAM (synchronous DRAM) 160 is an example of a semiconductor memory element, and a captured image is temporarily stored therein. The SDRAM 160 stores an operation program for the MPU 170.

  The MPU 170 functions as an arithmetic processing device and a control device according to a program, and can control processing of each component provided in the imaging device 100. The MPU 170 drives the imaging optical system 102 by outputting a signal to a driver based on, for example, focus control or exposure control. The MPU 170 controls each component of the imaging device 100 based on a signal from the operation unit. In the present embodiment, the MPU 170 is composed of only one, but it may be composed of a plurality of CPUs such that a signal system command and an operation system command are executed by separate CPUs.

  For example, the MPU 170 includes functional blocks such as an image shift position detection unit, a drive position calculation unit, a voltage polarity control unit, an aperture value acquisition unit, and a voltage value control unit.

  Next, each optical element provided on the subject side of the CCD 104 will be described with reference to FIGS. FIG. 2 is a sectional view showing each optical element and the CCD 104 of this embodiment. FIG. 3 is a front view showing the split image plate 110 of the present embodiment. FIG. 4 is a front view showing the split image plate 112 of the present embodiment.

  As shown in FIG. 2, the optical element provided on the subject side of the CCD 104 includes, for example, split image plates 110 and 112, optical LPFs (low pass filters) 113 and 114, an infrared light reflecting thin film 115, and the like. Each optical element is arranged in the order of the split image plate 110, the split image plate 112, the optical LPF 113, the optical LPF 114, and the infrared light reflecting thin film 115 in the direction from the CCD 104 to the subject side. The optical element is not limited to the example shown in FIG. 2, and may have other constituent members such as a phase plate, and the arrangement order may be configured in another order.

  Optical LPFs (low-pass filters) 113 and 114 are single crystal substrates that separate a subject image in a horizontal direction or a vertical direction, and can prevent false colors and moire by eliminating a high spatial frequency portion. For example, the optical LPF 113 separates the subject image in the horizontal direction, and the optical LPF 114 separates the subject image in the vertical direction. The infrared light reflecting thin film 115 reflects infrared light and can suppress ghost and fogging caused by infrared light.

  The split image plates 110 and 112 are configured by arranging two electro-optic effect members 202, 204, 302, and 304 each having an electro-optic effect on the same plane. The split image plates 110 and 112 shown in FIGS. 3 and 4 have a size capable of covering the entire imaging surface of the CCD 104.

  The split image plate 110 includes electro-optic effect members 202 and 204 that are long in the width direction of the CCD 104 and electrodes 212, 214, 222, and 224 provided at both ends of the electro-optic effect members 202 and 204. The split image plate 112 includes electro-optic effect members 302 and 304 that are long in the height direction of the CCD 104 and electrodes 312, 314, 322, and 324 provided at both ends of the electro-optic effect members 302 and 304.

  The operation of the split image plates 110 and 112 will be described with reference to FIG. FIG. 5 is a front view showing a graph showing the refractive index distribution and an imaging surface of the CCD 104.

  The electro-optic effect members 202, 204, 302, and 304 have a uniform refractive index distribution in the direction from one electrode to the other as shown in the non-operating state of FIG. 5A when no voltage is applied. Become. In addition, when a voltage is applied to the electrodes at both ends, the voltage application applies from one end to the other end of the incident surface of the electro-optic effect members 202, 204, 302, and 304, that is, from one electrode to the other electrode. The refractive index distribution is such that the refractive index gradually increases or decreases. For example, as shown in the operation state 1 in FIG. 5A, the distribution changes linearly in the direction from the electrode having the refractive index of 1 to the other electrode. Further, a voltage having the same value as that of the operating state 1 is applied, but by setting the opposite polarity, a refractive index distribution having a slope opposite to that of the operating state 2 as shown in the operating state 2 of FIG.

  Further, when the voltage applied in the operation state 2 is changed, the refractive index distribution is changed, and for example, as shown in the operation state 3 of FIG. . Note that these operations are performed by, for example, a voltage polarity control unit provided in the MPU 170.

  When voltages having opposite polarities are applied to the two electro-optic effect members 202 and 204 arranged above and below, as shown in FIGS. 5B and 5C, the subject image is not at the in-focus position. The subject image is shifted and formed on the imaging surface. Hereinafter, an image in which the subject is displaced is also referred to as a split image. For the two electro-optic effect members 302 and 304 arranged on the left and right sides, a split image is generated on the imaging surface by applying voltages having opposite polarities. When the split image disappears, the focus lens is driven to the in-focus position, and a focused subject image can be taken.

  For example, the case where the electro-optic effect member 202 is in the operating state 1 in FIG. 5A and the electro-optic effect member 204 is in the operating state 2 will be described. When the split image shown in FIG. 5B is obtained. The focus lens is a rear pin that is closer to the CCD 104 than the focus position. On the other hand, when the split image shown in FIG. 5C is obtained, the focus lens is a front pin that is closer to the subject than the focus position. is there. On the other hand, when the electro-optic effect member 202 is in the operation state 2 in FIG. 5A and the electro-optic effect member 204 is in the operation state 1, a split image shown in FIG. 5B is obtained. In this case, the focus lens is the front pin, while when the split image shown in FIG. 5C is obtained, the focus lens is the rear pin.

  In the case of manual focus, when the focus lens is driven in the infinity direction by manually operating the focus ring of the lens in the clockwise direction, the electro-optic effect member 202 is in the operation state 1, and the electro-optic effect member 204 is The voltage polarity control unit may apply a voltage so that the operation state 2 is obtained. When the split image of FIG. 5 (b) is obtained, if the focus ring is rotated counterclockwise to drive the focus lens in the closest direction, the split image 10a of FIG. 5 (b) moves to the left, The split image 10b moves to the right.

  On the other hand, when the focus lens is driven in the closest direction by manually operating the focus ring of the lens in the clockwise direction, the electro-optic effect member 202 is in operation state 2 and the electro-optic effect member 204 is in operation state 1. As such, the voltage polarity control unit may apply a voltage. When the split image of FIG. 5B is obtained, if the focus ring is rotated counterclockwise to drive the focus lens in the infinity direction, the split image 10a of FIG. 5B moves to the left. Then, the split image 10b moves to the right.

  As described above, when the polarity of the voltage applied to the electro-optic effect members 202 and 204 is changed based on the relationship between the moving direction of the focus lens and the manual operation direction for moving the focus lens, it is sensuously. This makes it easier to find the focus position.

  Note that the imaging apparatus 100 may acquire information indicating the relationship between the rotation direction of the focus ring and the movement direction of the focus lens from the lens of the image forming optical system 102 that is installed, or may be acquired by the user via the operation key 135. By setting, information indicating the relationship between the rotation direction of the focus ring and the movement direction of the focus lens may be acquired. The voltage polarity control unit changes the refractive index distribution of the electro-optic effect members 202 and 204 by changing the polarity of the voltage to be applied based on the acquired information.

  The voltage value of the applied voltage is controlled by, for example, a voltage value control unit provided in the MPU 170. Under the control of the voltage value control unit, the refractive index distribution generated in the split image plates 110 and 112 can be changed as in the difference between the operation state 2 and the operation state 3 in FIG. Further, the voltage value control unit changes the voltage value of the voltage applied to the split image plates 110 and 112 as shown in FIG. 6 based on the aperture value of the lens. FIG. 6 is a graph showing the relationship between the applied voltage and the aperture. The larger the aperture value, the lower the applied voltage. As a result, when the aperture value is large, the refractive index generated in the split image plates 110 and 112 is small, so that vignetting of the subject is eliminated. The aperture value acquisition unit is provided in the MPU 170, for example, and acquires the aperture value of a lens that forms a subject image on the imaging surface of the CCD 104.

  (Operation of the first embodiment)

  First, the focus processing in the manual focus (MF) mode will be described with reference to FIGS. FIG. 7 is a timing chart showing focus processing in the MF mode. FIG. 8 is an explanatory diagram showing a composition process when displaying an image in the MF mode.

  A timing generator 126 outputs a vertical synchronization signal (VD), and each process described later operates in synchronization with the synchronization signal. In the MF mode, no voltage is applied to the electrodes 312, 314, 322, and 324 of the split image plate 112, and focus detection is performed using only the split image plate 110. The split image plate 112 transmits the subject image as a transparent plate having no refractive index. The split image plate 110 is arranged closer to the CCD 104 than the split image plate 112, so that the shift position of the split image can be corrected and blurring can be further reduced.

  First, voltage is applied to the electrodes 212 and 224 of the split image plate 110 as the first frame. At this time, the electrodes 214 and 222 on the other end side are ground ends. When a voltage is applied to the electrodes 212 and 224, when the subject image is not focused on the imaging surface, a split image as indicated by ImgA in FIG. 8 is exposed on the imaging surface (ImgA1) (second image).

  In the next frame, no voltage is applied to the electrodes 212 and 224 of the split image plate 110. Therefore, the split image plate 110 transmits the subject image to the imaging surface as a transparent plate having no refractive index. At this time, a subject image that is not a split image as indicated by ImgB in FIG. 8 is exposed on the imaging surface (ImgB1) (first image). Subsequently, in the next frame, no voltage is applied to the electrodes 212 and 224 of the split image plate 110, and a subject image similar to ImgB as shown by ImgC in FIG. 8 is exposed on the imaging surface (ImgC1) (first 1 image). As described above, in the example shown in FIG. 7, the split image is exposed at the timing of one frame every three frames. The split image is not limited to the timing of one frame per three frames, and the split image may be exposed at an arbitrary timing.

  Reading the exposed subject image is performed one frame after the subject image exposure timing, as shown in FIG. The exposure calculation is performed using, for example, ImgC, which is a subject image that is not a split image. The subject image whose exposure is adjusted by the exposure calculation is reflected in the frame of the subject image ImgA3, which is the exposure timing after two frames.

  Next, in YC processing, the subject image ImgB or ImgC that is not a split image and the subject image ImgA that is a split image are combined (for example, ImgA1 + ImgB1, ImgA1 + ImgC1, etc.). From the subject image ImgA, images in the regions 203 and 204 are extracted, and the portions corresponding to the regions 203 and 204 of ImgB and ImgC are overwritten and combined. This composition is performed in the state of a RAW image.

  Note that the subject images on the imaging surfaces of the regions 203 and 204 may be combined with ImgB and ImgC after the relative position is moved by a predetermined amount by the image processing unit 152. Here, the predetermined amount is to correct a deviation due to a difference between the distance from the subject to the surface of the split image plate 110 and the distance from the subject to the imaging surface of the CCD 104. In addition, the movement of the relative position of the subject image may be performed, for example, when the shift amount of the split image is enlarged and displayed by user setting. Furthermore, the movement of the relative position of the subject image may be performed when the displacement amount is enlarged and displayed when the refractive index of the electro-optic effect members 202 and 204 is set to be small because the lens aperture value is large. . In this case, the movement of the subject image is performed based on the amount calculated for the enlarged display.

  The YC processing is performed in each subsequent frame after the subject image ImgB or ImgC that is not a split image is read. Further, the screen display displays the image generated by the YC process in the next frame. At this time, if the image to be displayed is not generated, the image of the previous frame is displayed again.

  Next, display image generation processing of the imaging apparatus 100 according to the present embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing display image generation processing of the imaging apparatus according to the present embodiment.

  First, the electrical signal of the image formed by the CCD 104 is digitally converted, and the digitally converted image signal is captured by the image processing unit 152 (step S101). Next, the image processing unit 152 generates the first image generated by the subject image on the imaging surface of the CCD 104 when no voltage is applied and the subject image on the imaging surface of the CCD 104 when the voltage is applied. In order to synthesize the second image that has been generated, or to correct the portion corresponding to the boundary between the electro-optic effect members 202 and 204, in order to suppress image disturbance that occurs at the ends of the electro-optic effect members 202 and 204 Image composition processing is performed (step S102).

  The image processing unit 152 performs white balance correction (step S103), CFA (Color filter array) interpolation (step S104), color reproduction processing (step S105), and tone reproduction processing (step S106) based on the image signal. .

  After the series of image processing, YCbCr conversion is performed on the image signal to generate a luminance signal and a color difference signal (step S107), and edge enhancement processing is performed (step S108). The generated image data is output to the image display unit 133, and the image display unit 133 acquires the display image and displays the image (step S109).

  Next, focus processing in the autofocus (AF) mode will be described with reference to FIGS. FIG. 10 is a flowchart showing focus processing in the AF mode. FIG. 11 is a timing chart showing focus processing in the AF mode.

  As shown in FIG. 11, the timing generator 126 generates a vertical synchronization signal (VD), and each process described later operates in synchronization with this synchronization signal. In the AF mode, a voltage is applied to the electrodes 212 and 224 of the split image plate 110 and the electrodes 312 and 324 of the split image plate 112. By this operation, a split image in the horizontal direction and the vertical direction can be obtained, so that the detection accuracy of the focus position is improved.

  First, voltage is applied to the electrodes 212 and 224 of the split image plate 110 as the first frame. At this time, the electrodes 214 and 222 on the other end side are ground ends. When the voltage is applied to the electrodes 212 and 224, when the subject image is not focused on the imaging surface, the split image separated in the vertical direction is exposed on the imaging surface (ImgA) (step S201).

  Next, as shown in FIG. 11, the readout of the exposed subject image is performed one frame after the subject image exposure timing (step S202). Then, for example, an image shift detection unit provided in the MPU 170 detects the shift position of the subject image on the imaging surface in the CCD 104 caused by refraction at the split image plates 110 and 112 based on the image signal by the electric signal output from the CCD 104. Is detected. Then, for example, the drive position calculation unit provided in the MPU 170 calculates the drive position of the focus lens based on the shift position detected by the image shift position detection unit. For example, using the read subject image data, the shift amount (for example, the number of pixels) of the split image is calculated by correlation calculation, and the focus lens position at which the subject is focused on the imaging surface is calculated (step S203). .

  In the next frame after the exposure of ImgA, a voltage is applied to the electrodes 312 and 324 of the split image plate 112. At this time, the electrodes 314 and 322 on the other end side are ground ends. When the voltage is applied to the electrodes 312, 324, if the subject image is not focused on the imaging surface, the split image separated in the horizontal direction is exposed on the imaging surface (ImgB) (step S204).

  Reading of the exposed subject image is performed one frame after the exposure timing of the subject image, as shown in FIG. 11 (step S205). Further, using the read subject image data, the shift amount (for example, the number of pixels) of the split image is calculated by correlation calculation, and the focus lens position at which the subject is focused on the imaging surface is calculated (step S206). .

  Next, based on the distance measurement calculation performed in step S203 and step S206, a focus lens position is determined so that the subject is focused on the imaging surface (step S207). Then, the focus lens is driven to move the focus lens to the calculated focus lens position (step S208). The focus lens is driven asynchronously with the vertical synchronization signal as shown in FIG.

  Then, after the focus lens is moved, the split image plate 110 or the split image plate 112 is operated again for confirmation of focusing (step S209). In the example shown in FIG. 11, a voltage is applied to the electrodes 212 and 224 of the split image plate 110 at the timing of the vertical synchronization signal immediately after the driving of the focus lens is completed, and the split image is exposed on the imaging surface (ImgC). . Then, as shown in FIG. 11, the exposed subject image ImgC is read out one frame after the subject image exposure timing (step S210). Note that which of the split image plates 110 and 112 is moved is determined in step S207.

  Further, using the read subject image data, the shift amount (for example, the number of pixels) of the split image is calculated by correlation calculation, and it is determined whether or not it is in focus. At the same time, it is determined whether or not a preset upper limit loop number of focus operations is satisfied (step S211). When the focusing condition is satisfied or the number of loops exceeds the upper limit, the AF mode focus processing is completed.

  After the above focusing process is completed, the imaging process is performed in a state where the voltage application to the split image plates 110 and 112 is released, and the image data is recorded.

  Next, with reference to FIG. 12, a recorded image generation process of the imaging apparatus 100 according to the present embodiment will be described. FIG. 12 is a flowchart showing a recorded image generation process of the imaging apparatus according to the present embodiment.

  First, the electrical signal of the image formed by the CCD 104 is digitally converted, and the digitally converted image signal is captured by the image processing unit 152 (step S301). Next, the image processing unit 152 performs an image interpolation process such as correcting a portion corresponding to the boundary between the electro-optic effect members 202, 204, 302, and 304 (step S302). The image processing unit 152 performs white balance correction (step S303), CFA (Color filter array) interpolation (step S304), color reproduction processing (step S305), and tone reproduction processing (step S306) based on the image signal. .

  After the series of image processing, YCbCr conversion is performed on the image signal to generate a luminance signal and a color difference signal (step S307), and edge enhancement processing is performed (step S308). Then, the compression processing unit 150 performs Jpeg coding to generate Jpeg-format compressed data (step S309). The generated compressed data is recorded in, for example, the memory card 131, and acquisition of the captured image is completed (step S310).

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, in the above-described embodiment, the split image plates 110 and 112 have almost the same area as the CCD 104, but the present invention is not limited to such an example. For example, as shown in FIG. 13, the split image plate 400 may have a size that covers a part of the CCD 104. FIG. 13 is a front view showing a modification example of the split image plate of the present embodiment. The split image plate 400 includes electro-optic effect members 402 and 404 and electrodes 412, 414, 422 and 424.

  Further, the electro-optic effect member made up of a combination of two pieces in the split image plates 110, 112, and 400 has been described with respect to the case where the both ends are in contact with each other at approximately the center of the CCD 104, but the present invention is applied. It is not limited to examples. For example, the electro-optic effect member may be arranged so that a split image is formed at an arbitrary position other than the center of the imaging surface. Also, a plurality of electro-optic effect members can be installed so that the split image is generated not only at one place but at a plurality of places.

1 is a block diagram illustrating an imaging apparatus according to a first embodiment of the present invention. It is sectional drawing which shows each optical element and CCD of the embodiment. It is a front view which shows the split image board of the embodiment. It is a front view which shows the split image board of the embodiment. It is a front view which shows the graph which shows refractive index distribution, and the imaging surface of CCD. It is a graph which shows the relationship between the applied voltage and aperture stop of the split image board of the embodiment. It is a timing chart which shows the focus process of MF mode. It is explanatory drawing which shows the synthetic | combination process in the case of the image display at the time of MF mode. It is a flowchart which shows the display image generation process of the imaging device which concerns on the embodiment. It is a flowchart which shows the focus process of AF mode. It is a timing chart which shows the focus process of AF mode. 4 is a flowchart showing a recorded image generation process of the imaging apparatus according to the embodiment. It is a front view which shows the example of a change of the split image board of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Imaging device 102 Imaging optical system 104 CCD
106 Motor drive unit 108 Serial I / F
110, 112, 400 Split image plate 113, 114 Optical LPF
115 Infrared light reflective thin film 120 AFE
122 AGC
124 A / D converter 126 Timing generator 130 Card I / F
131 Memory card 132 Video I / F
133 Image display part 134 Key I / F
135 Operation Key 150 Compression Processing Unit 152 Image Processing Unit 160 SDRAM
170 MPU
202, 204, 302, 304, 402, 404 Electro-optic effect member 212, 214, 222, 224, 312, 314, 322, 324, 412, 414, 422, 424 Electrode

Claims (8)

  A light incident surface is arranged on the optical path from the subject to the imaging surface, and has a refractive index distribution in which the refractive index gradually increases or decreases gradually from one end to the other end in the surface direction of the incident surface by applying a voltage by having an electro-optic effect. An imaging apparatus comprising: an optical element that is formed and transmits an image of the subject toward the imaging surface. An image sensor that is disposed on the imaging surface on which light from the subject that has passed through the optical element forms an image, and that converts the light into an electrical signal by photoelectric conversion;
An image shift position detector that detects a shift position of the subject image on the imaging surface caused by refraction by the optical element based on the electrical signal;
A focus lens drive control unit that controls driving of a focus lens that focuses the subject image on the imaging surface by moving in an optical axis direction;
A drive position calculation unit that calculates a drive position of the focus lens based on the detected displacement position;
The imaging apparatus according to claim 1, further comprising: An image sensor that is disposed on the imaging surface on which light from the subject forms an image, and that converts the light into an electrical signal by photoelectric conversion;
Based on the electrical signal, the first image generated by the subject image on the imaging surface when no voltage is applied and the subject image on the imaging surface when the voltage is applied An image processing unit for synthesizing the second image that has been performed;
An image display control unit for causing the image display unit to display the composite image synthesized by the image processing unit;
The imaging apparatus according to claim 1, further comprising:   4. The image processing unit according to claim 3, wherein the first image and the second image are combined by moving a relative position of a plurality of regions in the second image by a predetermined amount. The imaging device described.   Applied to the optical element based on the relationship between the moving direction of the focus lens that focuses the subject image on the imaging surface by moving in the optical axis direction and the manual operation direction for moving the focus lens The imaging apparatus according to claim 3, further comprising a voltage polarity control unit that changes a polarity of the voltage to be applied. An aperture value acquisition unit that acquires an aperture value of a lens that forms the subject image on the imaging surface;
A voltage value control unit that changes a voltage value applied to the optical element based on the acquired aperture value;
With
The imaging apparatus according to claim 1, wherein the optical element changes the refractive index according to the voltage value.   The image processing apparatus according to claim 1, wherein a predetermined correction process is performed on an image corresponding to an end portion of the optical element among images formed on the imaging surface through the optical element. The imaging device described in 1. The optical element in which the light incident surface is arranged on the optical path from the subject to the imaging surface has an electro-optic effect, so that the refractive index gradually increases or decreases from one end to the other end in the surface direction of the incident surface due to voltage application. Forming a refractive index profile;
An image sensor disposed on the imaging surface on which light from the subject that has passed through the optical element forms an image, and converts the light into an electrical signal by photoelectric conversion;
Detecting a shift position of the subject image on the imaging surface caused by refraction at the optical element based on the electrical signal;
Controlling the driving of a focus lens for focusing the subject image on the imaging surface by moving in an optical axis direction;
Calculating a drive position of the focus lens based on the detected displacement position;
The imaging method characterized by including.

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