JP4517292B2 - Frame sequential color image pickup device - Google Patents

Description

  The present invention relates to a field sequential color image pickup apparatus, and more particularly to a technique for preventing a positional shift between frame sequential color images.

  In general, the field sequential color image pickup device rotates a rotating color filter having three primary color filters, and each time the color filter moves on the photographing optical axis of the photographing optical system, the subject is passed through the color filter. Are picked up by a black and white image pickup device, images corresponding to the respective colors are sequentially taken in, and then the respective images are combined to obtain a color image.

  This type of surface sequential color image pickup device cannot sufficiently ensure the orthogonal accuracy between the surface of each color filter and the photographing optical axis due to the shake of the rotating shaft of the rotating color filter and the mounting accuracy of the color filter. For this reason, there is a problem in that the position of the subject image on the imaging plane is shifted according to the rotational position of the rotating color filter.

In order to solve this problem, the frame-sequential color camera described in Patent Document 1 is configured to slightly displace the two-dimensional solid-state imaging device in accordance with the displacement of the optical image accompanying the rotation of the rotating color filter. That is, in the invention described in Patent Document 1, when the rotating color filter is tilted with respect to the photographing optical axis, one point of the optical image becomes a circle on the image plane as the rotating color filter rotates. Focusing on the drawing, the two-dimensional solid-state imaging device is caused to make a circular motion in synchronization with the rotation of the rotating color filter.
JP-A-6-319143

  In the invention described in Patent Document 1, the surface of the rotating color filter is inclined by a predetermined angle with respect to the photographing optical axis, and two-dimensionally corresponding to the displacement of the optical image accompanying the rotation of the inclined rotating color filter. Although the solid-state image sensor is slightly displaced, it is assumed that the deviation of the optical image on the image plane is known according to the rotational position of the rotating color filter. Therefore, the invention described in Patent Document 1 cannot be applied when the angle between the surface of the rotating color filter and the photographing optical axis varies randomly due to the shake of the rotating shaft of the rotating color filter.

  In order to rotate the rotating color filter, a gap is required between the photographing optical system and the color filter. However, if light that does not pass through the color filter enters from the gap during photographing, there is a possibility that the color may not be accurately reproduced when obtaining a color image.

  The present invention has been made in view of such circumstances, and can ensure sufficient orthogonal accuracy between the surface of each color filter and the photographic optical axis, thereby preventing any positional deviation on the imaging surface. It is an object of the present invention to provide a frame sequential color image pickup apparatus that can obtain sequential color images and can prevent light from entering without passing through a color filter during photographing.

In order to achieve the above object, a frame sequential color image capturing apparatus according to the first aspect of the present invention includes a monochrome imaging unit, a color filter of at least three primary colors, and a filter holding member that holds each color filter with play. A positioning member disposed in the vicinity of the filter holding member and having a reference plane parallel to the imaging surface of the black and white image pickup means; A first filter driving unit that is sequentially switched and arranged on an axis; a second filter driving unit that drives the filter holding member to bring the color filter into contact with a reference surface of the positioning member; and and an imaging control means for acquiring the color filter means and controlled by the frame sequential color image data to monochrome image pickup means, said second filter Motion means comprises a cam which drives the filter holding member to the photographing optical axis direction, and wherein Rukoto and a motor for rotating the cam.

In the frame sequential color image pickup apparatus according to the first aspect , each color filter is held with play by a filter holding member, and fine adjustment of the position and inclination of the color filter in the photographing optical axis direction is possible. It has become. The color filter moved on the photographing optical axis by the filter driving means is urged by the filter urging means and is brought into contact with the reference surface of the positioning member. The flatness of the surface of each color filter that comes into contact with the reference surface has a desired accuracy. When this surface comes into contact with the reference surface, the surface of the color filter is parallel to the reference surface, and as a result, monochrome imaging. Parallel to the imaging plane of the means.

Field sequential color imaging apparatus according to the second aspect of the present invention, in the first aspect, and further comprising a filter biasing means for biasing said filter holding member to the reference surface of the positioning member To do.

According to the field sequential color image pickup device according to the second aspect of the present invention, the filter holding member is biased to the reference surface of the positioning member, so that the color filter can be kept accurately parallel to the reference surface. .

In the frame sequential color image pickup device according to the third aspect of the present invention, in the first or second aspect , the filter holding member is held movably in the photographing optical axis direction, and the color filter is fixed. The filter urging means is a spring that urges the filter frame toward the reference surface. In the third aspect , the filter urging means of the second aspect is limited to a spring.

In the frame sequential color image capturing apparatus according to the fourth aspect of the present invention, in the first to third aspects , the filter holding member is rotatably disposed in front of the photographing optical system of the monochrome imaging means. The first filter driving means drives the turret plate to rotate to move each color filter onto the optical path of the photographing optical system.

According to the field sequential color image pickup device according to the fourth aspect, when the surface of each color filter held on the turret plate is tilted by tilting of the rotation shaft of the turret plate, each color By bringing the surface of the filter into contact with the reference surface, the tilt of the surface of the color filter can be corrected.

According to a fifth aspect of the present invention, in the first to fourth aspects , the positioning member is arranged such that the positioning member is arranged on the optical path of the photographing optical system of the black and white image pickup unit. And a cover member having a shape following the photographing optical system.

According to the field sequential color image capturing apparatus according to the fifth aspect , it is possible to prevent the incidence of disturbance light by covering the tip of the photographing optical system with the cover member. Further, since the cover member and the photographing optical system are kept in non-contact, the relative positional relationship between the photographing optical system and the color filter does not shift even when the color filter is biased to the reference surface.

  According to the present invention, each color filter is brought into contact with a reference plane parallel to the imaging surface of the black and white imaging means so that the surface of each color filter is parallel to the imaging surface of the black and white imaging means. Therefore, it is possible to eliminate the tilting of the surface of each color filter, and thereby it is possible to obtain a surface-sequential color image with no positional deviation on the imaging surface. Further, by preventing the incidence of disturbance light, the color can be accurately reproduced.

  Hereinafter, preferred embodiments of a frame sequential color image pickup apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an external view showing a frame sequential color image pickup apparatus according to an embodiment of the present invention, and FIG. 2 is a top view thereof. The frame sequential color image pickup apparatus 10 shown in FIG. 1 mainly includes an image pickup apparatus main body 12 and a rotary color filter apparatus 14, and each is disposed on a support base 16. The imaging device body 12 is fixed to the support base 16 via a head mechanism (not shown), and the position and angle of the rotary color filter device 14 can be finely adjusted by the head mechanism. .

  The rotating color filter device 14 has a turret plate 20 that holds color filters 18 of at least three primary colors. The color filter 18 is held by a filter frame 22. The filter frame 22 is held by a guide shaft 24 pivotally attached to the turret plate 20 so as to be movable in the photographing optical axis direction (straight line AX direction in the figure). The filter frame 22 is biased by a spring 26 in a direction away from the turret plate 20 (left direction in FIG. 2). In FIG. 2, only one guide shaft 24 and one spring 26 are illustrated, but actually, a plurality of (for example, three to five) are provided around the color filter 18.

  The turret plate 20 is provided with a color filter designed to have a spectral sensitivity so as to reduce an error when linearly converted to a CIE (International Commission on Illumination) color matching function. The color filter may be an RGB color filter or a CMY color filter. In the case of multiband measurement for estimating the reflectance, color bandpass filters of six colors or more are attached.

  A positioning member 30 is disposed between the imaging lens 28 and the turret plate 20 of the imaging apparatus main body 12. The positioning member 30 is disposed at a position not in contact with the imaging lens 28. An opening 30 </ b> A is provided at a position facing the imaging lens 28 of the positioning member 30.

  Next, a mechanism for driving the turret plate 20 will be described with reference to FIG. FIG. 3 is a perspective view showing a mechanism for driving the turret plate 20. A rotation shaft 32 is fixed to the center of the turret plate 20. The rotation shaft 32 is substantially parallel to the photographing optical axis of the image pickup apparatus body 12 and is rotatably supported by a bearing member 34. A rotation direction drive motor 36 is attached to the end of the rotation shaft 32, and the rotation drive force from the rotation direction drive motor 36 is transmitted to the turret plate 20. Thereby, the turret plate 20 is rotationally driven by the rotational direction drive motor 36.

  The bearing member 34 is attached to the moving plate 38. The moving plate 38 is a member that holds the rotation shaft 32 and the rotation direction drive motor 36. A moving stage 40 </ b> A of the linear motion linear guide 40 is attached to the bottom surface of the moving plate 38. On the other hand, the fixed stage 40 </ b> B of the linear motion linear guide 40 is fixed to the bracket 42.

  An axial drive motor 44 is fixed to the bracket 42 by a holding member (not shown). A disk 46 is disposed at the upper end of the rotation shaft 44A of the axial drive motor 44, and a pin 46A is disposed at a position displaced on the disk 46 by a predetermined distance from the rotation shaft 44A. . The pin 46 </ b> A is fitted in a slot 48 provided in the moving plate 38, and the moving plate 38 is driven in the direction of the rotating shaft 32 as the axial direction driving motor 44 rotates.

  Next, the procedure for driving the turret plate 20 and replacing the color filter 18 will be described with reference to FIGS. 4 is a cross-sectional view taken along line 4-4 of FIG. As shown in FIG. 4, the opening 30 </ b> A of the positioning member 30 has a cylindrical shape protruding toward the filter frame 22, and a reference surface 30 </ b> A is formed facing the filter frame 22. The reference plane 30A is a plane orthogonal to the photographing optical axis AX, and is a plane parallel to the imaging plane of the monochrome imaging element (reference numeral 60 in FIG. 5).

  When the disk 46 is rotated by a predetermined angle (180 degrees in the case of FIG. 3) by the axial drive motor 44, the pins 46A move simultaneously. Accordingly, the moving plate 38 moves to the right in FIG. 3 (that is, the turret plate 20 moves away from the imaging lens 28) twice the displacement distance of the pin 46A from the rotation shaft 44A. Then, as shown to Fig.4 (a), engagement with the filter frame 22 and the positioning member 30 is lose | eliminated, and the turret board 20 will be in the state of free rotation. Here, when the turret plate 20 is rotated by a predetermined angle (for example, 90 degrees) by the rotation direction drive motor 36, the color filter 18 is replaced.

  Next, when the disk 46 is rotated again by a predetermined angle (for example, 180 degrees) by the axial drive motor 44, the moving plate 38 moves in the left direction in FIG. 3 (that is, the turret plate 20 approaches the imaging lens 28). Move). Then, as shown in FIG. 4B, the filter frame 22 comes into contact with the reference surface 30 </ b> A of the positioning member 30. The filter frame 22 is urged against and closely contacts the reference surface 30 </ b> A of the positioning member 30 by the spring 26. As a result, the color filter 18 is parallel to the reference plane 30A of the positioning member 30 (further, the black and white image sensor (image forming plane indicated by reference numeral 60 in FIG. 5)).

  As shown in FIG. 4, the filter frame 22 and the imaging lens 28 are in a non-contact relationship, so that the elastic force of the spring 26 does not act on the imaging lens 28. Further, since the filter frame 22 is biased toward the reference surface 30A by the spring 26, the relative position between the color filter 18 and the imaging lens 28 can be accurately maintained regardless of the mounting accuracy of the color filter 18 on the turret plate 20. .

  According to the present embodiment, the color filter 18 can be replaced while accurately maintaining the relative positional relationship between the color filter 18 and the imaging lens 28 by repeating the above operation.

  Further, since the turret plate 20 is configured to go straight by the engagement of the pin 46A of the circular plate 46 and the elongated hole portion 48 of the moving plate 38, the turret plate can be used even when the surface sequential color image pickup device 10 is tilted. The relative position of the color filter 18 and the imaging lens 28 does not shift due to a weight of 20 or the like. For this reason, the frame sequential color image capturing apparatus 10 of the present embodiment has an advantage that photographing is possible regardless of the posture.

  Further, as shown in FIG. 4, the imaging lens 28 is inserted into the opening 30 </ b> A of the positioning member 30 with an appropriate space. The space between the imaging lens 28 and the opening 30 </ b> A is adjusted so that light (disturbance light) other than incident light entering through the color filter 18 does not enter the imaging lens 28. Thereby, since the incidence of disturbance light can be prevented, the color can be accurately reproduced when a color image is obtained.

  In this embodiment, the rotational direction drive motor 36 and the axial direction drive motor 44 are directly connected to the driven member (the turret plate 20 and the circular plate 46). It goes without saying that the effect of can be obtained.

  FIG. 5 is a block diagram illustrating a main configuration of the frame sequential color image capturing apparatus 10. As described above, the frame sequential color image capturing apparatus 10 according to the present embodiment includes the imaging apparatus main body 12 and the rotating color filter apparatus 14, and the frame sequential color image captured via the rotating color filter apparatus 14. An image is recorded on the memory card 50. The overall operation of the field sequential color image capturing apparatus 10 is controlled by a central processing unit (CPU) 52. The ROM 54 stores programs, adjustment values, and the like in advance, and these programs, adjustment values, and the like are read as appropriate.

  The image pickup apparatus body 12 is provided with an operation unit 56 including a shutter button and a mode dial for setting a shooting mode, a reproduction mode, and the like, and a signal corresponding to an operation on the operation unit 56 is input to the CPU 52. .

  Image light indicating a subject is imaged on a light receiving surface (imaging surface) of a black and white image sensor 60 such as a CCD image sensor or a CMOS image sensor via the rotating color filter device 14, the imaging lens 28, and the aperture 58.

  The turret plate 20 of the rotary color filter device 14 is rotationally driven by a filter drive unit 62, a rotary direction drive motor 36, and an axial direction drive motor 44 controlled by the CPU 52, and each color filter 18 is picked up by an imaging lens for each frame sequential shooting. It is controlled so as to be positioned on 28 photographing optical axes AX.

  The imaging lens 28 is driven by a lens driving unit 64 controlled by the CPU 52, and focus control and the like are performed. The diaphragm 58 is composed of, for example, five diaphragm blades, and is driven by a diaphragm driving unit 66 controlled by the CPU 52. For example, the diaphragm 58 is controlled in five steps from the aperture value F2.8 to F11 in increments of 1AV.

  The CPU 52 controls the diaphragm 58 via the diaphragm drive unit 66 and controls the charge accumulation time (shutter speed) in the monochrome image sensor 60 via the image sensor control unit 68.

  The signal charge accumulated in the monochrome image sensor 60 is read out as a voltage signal corresponding to the signal charge based on the readout signal applied from the image sensor control unit 68. The voltage signal read from the black and white image sensor 60 is applied to the analog signal processing unit 70, where the voltage signal for each pixel is sampled and held, amplified, and then applied to the A / D converter 72. The A / D converter 72 converts analog signals that are sequentially input into digital signals, and the digital signals (image data) are temporarily stored in a memory (SDRAM) 76 via the image input controller 74.

  The image data stored in the memory 76 is output to the VRAM 80 after required signal processing is performed via the digital signal processing unit 78. The VRAM 80 includes an A area and a B area each storing image data representing an image for one frame. In the VRAM 80, image data representing an image for one frame is rewritten alternately in the A area and the B area. Of the A area and B area of the VRAM 80, the written image data is read from an area other than the area where the image data is rewritten. The image data read from the VRAM 80 is encoded by the video encoder 82 and output to a liquid crystal monitor (LCD) 84 provided on the back surface of the imaging device 12. As a result, the subject image is displayed on the display screen of the liquid crystal monitor 84.

  In addition, when the shutter button of the operation unit 56 is first pressed (half-pressed), the AE operation and the AF operation are started. That is, the image data output from the A / D converter 72 is taken into the AF detection unit 86 and the AE detection unit 88. The AF detection unit 86 uses image data (for example, a signal in the central area (focus area) of the black and white image sensor 60) and uses a high-pass filter (HPF) to extract high-frequency components from one-dimensional horizontal continuous image data. A value (AF evaluation value) obtained by extracting and integrating the high frequency components is output to the CPU 52. The AE detection unit 88 integrates the image data of the entire screen, or integrates the image data with different weights in the central portion and the peripheral portion of the screen, and outputs the integrated value to the CPU 52.

  Based on the AF evaluation value input from the AF detection unit 86, the CPU 52 moves the imaging lens 28 via the lens driving unit 64 to the lens position where the AF evaluation value is maximized, and the integration input from the AE detection unit 88. The brightness of the subject (shooting Ev value) is calculated from the value, and the aperture value of the aperture 58 and the electronic shutter (shutter speed) of the monochrome imaging device 60 are determined based on the shooting Ev value according to a predetermined program diagram. Based on the determined aperture value, the aperture 58 is controlled via the aperture drive unit 66, and the charge accumulation time in the monochrome image sensor 60 is controlled via the image sensor control unit 68 based on the determined shutter speed.

  When the AE operation and the AF operation are completed and the shutter button is pressed in the second stage (full press), frame-sequential imaging is performed in response to the depression, and the image data for each color in the frame sequence is the image data Temporarily stored in the memory 76 via the input controller 74.

  The digital signal processing unit 78 performs predetermined signal processing such as offset control, gain control processing including white balance correction and sensitivity correction, gamma correction processing, and YC processing on the image data stored in the memory 76. The YC-processed image data (YC data) is read from the digital signal processing unit 78 and stored in the memory 76 again. Subsequently, the YC data is output to the compression / decompression processing unit 90, and a predetermined compression process such as JPEG (Joint Photographic Experts Group) is executed. The compressed YC data is output and stored again in the memory 76, read out by the media controller 92, and recorded in the memory card 50.

  When RAW data recording is performed, image data stored in the memory 76 via the image input controller 74 (frame sequential image data not subjected to signal processing or the like in the digital signal processing unit 78) is stored. It is recorded in the memory card 50 as it is.

  Next, a procedure for capturing a frame sequential color image will be described with reference to FIG. FIG. 6 is a flowchart showing a procedure for capturing a frame sequential color image. First, the axial drive motor 44 is controlled via the filter drive unit 62 controlled by the CPU 52, and the turret plate 20 moves so as to approach the imaging lens 28 (step S10). As a result, as shown in FIG. 4B, the filter frame 22 of the color filter 18 held by the turret plate 20 is biased by the spring 26 to the reference surface 30A of the positioning member 30, and the color filter 18 is moved to the reference surface. Parallel to 30A. That is, the tilt of the color filter 18 with respect to the photographing optical axis AX can be corrected. It is assumed that one of the color filters 18 is positioned on the photographing optical axis while the turret plate 20 is stopped.

  Subsequently, the subject is imaged by the imaging device 12 (step S12). This imaging is an imaging for one time out of a plurality of times of imaging performed in a frame sequential manner.

  Next, it is determined whether or not the imaging of all the color planes has been completed (step S14). If completed, the frame sequential color image imaging operation is terminated, If the imaging has not ended, the process proceeds to step S16.

  Thereafter, the turret plate 20 is moved away from the imaging lens 28 by the axial drive motor 44. Thereby, as shown to Fig.4 (a), engagement with the filter frame 22 and the positioning member 30 is lose | eliminated, and the turret board 20 becomes rotatable (step S16).

  In step S <b> 18, the CPU 52 controls the filter drive unit 62 to supply drive power to the rotation direction drive motor 36 to rotate the turret plate 20 (turn the rotation direction drive motor 36 ON). Then, with the rotation of the turret plate 20, it is determined whether or not the next color filter has moved on the photographing optical axis AX (step S20). The direction drive motor 36 is turned off (step S22). And when rotation of turret board 20 stops, it will return to Step S10.

  By repeating step S10 to step S22, frame sequential color images are captured.

  In the present embodiment, the color filter 18 is replaced by rotating the turret plate 20, but the present invention is not limited to this. For example, the present invention can be applied to a configuration in which a plate-like member on which the color filters 18 are arranged and held is slid, or a configuration in which the color filters 18 are manually replaced one by one.

1 is an external view showing a frame sequential color image pickup apparatus according to an embodiment of the present invention. 1 is a top view showing a frame sequential color image pickup apparatus according to an embodiment of the present invention. A perspective view showing a mechanism for driving the turret plate 20 Sectional view along line 4-4 in FIG. The block diagram which shows the main structures of the field sequential color image pick-up device 10 Flow chart showing imaging procedure of frame sequential color image

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Frame sequential color image pick-up device, 12 ... Imaging device main body, 14 ... Rotation color filter device, 16 ... Support stand, 18 ... Color filter, 20 ... Turret plate, 22 ... Filter frame, 24 ... Guide shaft, 26 ... Spring , 28 ... Imaging lens, 30 ... Positioning member, 32 ... Rotating shaft, 34 ... Bearing member, 36 ... Rotation direction drive motor, 38 ... Moving plate, 40 ... Linear motion linear guide, 42 ... Bracket, 44 ... Axial direction drive motor , 46 ... disk, 48 ... slot part, 50 ... memory card, 52 ... central processing unit (CPU), 54 ... ROM, 56 ... operation part, 58 ... aperture, 60 ... monochrome imaging element, 62 ... filter drive part 64 ... Lens drive unit, 66 ... Aperture drive unit, 68 ... Image sensor control unit, 70 ... Analog signal processing unit, 72 ... A / D converter, 74 ... Image input controller, 76 ... Menu (SDRAM), 78 ... Digital signal processing unit, 80 ... VRAM, 82 ... Video encoder, 84 ... Liquid crystal monitor (LCD), 86 ... AF detection unit, 88 ... AE detection unit, 90 ... Compression / decompression processing unit, 92 ... Media controller

Claims (5)

Black and white imaging means;
At least three primary color filters;
A filter holding member for holding each color filter with play;
A positioning member disposed in the vicinity of the filter holding member and having a reference surface parallel to the imaging surface of the black and white imaging means;
First filter driving means for driving the filter holding member to sequentially switch and arrange each color filter on the photographing optical axis of the monochrome imaging means;
Second filter driving means for driving the filter holding member to bring the color filter into contact with a reference surface of the positioning member;
And an imaging control means for obtaining a field sequential color image data by controlling the color filter means and monochrome imaging means when the imaging of a subject,
The second filter driving means includes
A cam for driving the filter holding member in the photographing optical axis direction;
A motor for rotating the cam;
Field sequential color imaging apparatus comprising: a. Further comprising that claim 1 Symbol placement plane sequential color imaging apparatus characterized by a filter biasing means for biasing the reference surface of the positioning member the filter support member. The filter holding member includes a filter frame that is held movably in the photographing optical axis direction and fixes the color filter.
3. The frame sequential color image pickup apparatus according to claim 1, wherein the filter urging means is a spring that urges the filter frame toward the reference plane. The filter holding member is composed of a substantially circular turret plate rotatably disposed in front of the photographing optical system of the black and white imaging means,
The first filter driving means sequentially face of any one of claims 1 to 3, wherein the moving the color filters by driving rotating the turret plate on an optical path of the imaging optical system Color image capturing device. The positioning member is disposed on the optical path of the photographic optical system of the black and white imaging means with a gap provided between the positioning member and the photographic optical system, and includes a cover member shaped to follow the photographic optical system. field sequential color imaging apparatus according to any one of claims 1, wherein 4.

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