JP4359772B2 - Image capturing method for frame sequential color image and image capturing apparatus for frame sequential color image - Google Patents

Description

  The present invention relates to a frame sequential color image capturing method and a frame sequential color image capturing apparatus, and more particularly, to a technique for preventing positional deviation between frame sequential color images.

  In general, a field sequential color image capturing apparatus rotates a rotating color filter having RGB color filters, and each time a color filter moves on the optical axis of a photographic optical system, the object is converted into black and white via the color filter. Images are picked up by an 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.

  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 field sequential color image imaging method and a field sequential color image imaging apparatus capable of obtaining sequential color images.

In order to achieve the above object, the invention according to claim 1 uses a field sequential color image pickup device comprising a monochrome image pickup means, a color filter of at least three primary colors, a filter drive means, and a filter biasing means, in the imaging method of the field sequential color image to acquire color image data in area order by imaging a subject by the monochrome image pickup means switches the color of the color filter, by driving the filter drive means by the central processing unit, each of the color A first step of sequentially moving the filter on the photographing optical axis of the black and white imaging means, and a color filter of any color is moved on the photographing optical axis of the black and white imaging means by the first step; wherein the central processing unit to operate the biasing means the filter, the optical axis direction of the color filter which has moved onto the photographing optical axis of the monochrome image pickup means Biased in a second step of contact with the imaging surface parallel to the reference plane of the monochrome image pickup device, the monochrome image pickup by the control of the central processing unit after the color filter is in contact with the reference surface look including a third step of performing imaging by means to the imaging of all the colors of the face by the control of the central processing unit is completed, the first step, second step and third step Is repeated in order .

  The cause of the positional deviation between the respective surfaces on the image forming surface of the optical image picked up in the surface sequential order is the tilt of the surface of each color filter with respect to the image forming surface. Therefore, in the invention according to claim 1, each color filter is brought into contact with a reference plane parallel to the imaging surface of the black and white imaging means, and the surface of each color filter and the imaging surface of the monochrome imaging means are made parallel. (That is, the surface of each color filter is not tilted.) After that, the image is picked up by the black-and-white image pickup means, thereby obtaining a surface-sequential color image with no positional deviation on the image plane. I am doing so.

  According to a second aspect of the present invention, there is provided a black and white image pickup means and a color filter means having at least three primary color filters, wherein each color filter is sequentially switched and arranged on the photographing optical path of the black and white image pickup means, An image-sequential color image capturing apparatus comprising an image-capturing control unit that controls the color filter unit and the monochrome image-capturing unit to acquire frame-sequential color image data, wherein the color filter unit plays each color filter with play. A filter holding member for holding, 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 imaging means, and driving the filter holding member to each color filter Filter driving means for moving on the photographing optical axis of the monochrome imaging means, and photography of the monochrome imaging means by the filter driving means A filter which is moved over the shaft, is characterized by having a filter biasing means is brought into contact with the reference surface of the positioning member.

  Each color filter is held with play by a filter holding member, and the position and inclination of the color filter in the photographing optical axis direction can be finely adjusted. 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.

  3. The field sequential color image capturing apparatus according to claim 2, wherein the filter holding member is a substantially circular turret plate rotatably disposed in front of a photographing optical system of the black and white image capturing means. The filter driving means is characterized in that each color filter is moved on the optical axis of the photographing optical system by rotationally driving the turret plate. Although the surface of each color filter held on the turret plate is tilted due to a swing of the rotation shaft of the turret plate, the surface of the color filter is brought into contact with the reference surface by bringing the surface of each color filter into contact with the reference surface. The fall can be corrected.

  4. The field sequential color image pickup device according to claim 2, wherein the filter urging means is an electromagnet that urges the color filter so as to abut on a reference surface of the positioning member. A vacuum control unit; and a drive control unit that operates the electromagnet or the vacuum unit for a certain period including an imaging period of the monochrome imaging unit each time each color filter moves on the optical axis of the imaging optical system. It is said.

  Each time each color filter moves on the optical axis of the photographic optical system, the electromagnet or vacuum means is operated for a certain period so that the electromagnet or vacuum means does not become a resistance when the color filter moves.

  5. The field sequential color image pickup device according to claim 2, wherein the filter urging means is incorporated in the filter holding member, and each color held by the filter holding member with play. The filter is a spring member that urges the filter with elasticity in a direction in contact with the reference surface of the positioning member.

  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.

  Preferred embodiments of a field sequential color image capturing method and a field sequential color image capturing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is an external view showing an embodiment of a frame sequential color image pickup apparatus according to the present invention. As shown in the figure, the frame sequential color image capturing apparatus 10 is mainly composed of an image capturing apparatus main body 100 and a rotating color filter apparatus 200, and each is disposed on a support base 20. Note that the imaging apparatus main body 100 is fixed to the support base 20 via a head mechanism (not shown), so that the position and angle of the rotary color filter apparatus 200 can be finely adjusted.

  The rotating color filter device 200 includes a turret plate 202 that holds color filters of R (red), G (green), B (blue), C (cyan), M (magenta), and Y (yellow). Yes. A support shaft 203 is fixed to the center of the turret plate 202, and the support shaft 203 is rotatably supported by a bearing (not shown) and transmits a rotational driving force from a motor 204 (see FIG. 4). It has become. Thereby, the turret plate 202 is rotationally driven by the motor 204. The turret plate 202 is provided with XYX or RGB as a primary color system and a CMY color filter as a complementary color system. In the case of multiband measurement for estimating the reflectance, six or more color bandpass filters are attached.

  The turret plate 202 is covered with a cover 206 having openings 206A and 206B in part. The opening 206 </ b> A of the cover 206 is formed at a position facing the photographing lens 112 of the imaging apparatus main body 100.

  A cam 202A for positioning each color filter at a predetermined position (a position of the opening 206A of the cover 206) is formed on the outer periphery of the turret plate 202. The cam 202A includes a roller of the lever member 208. The portion 208A comes into contact. The lever member 208 is biased so that the roller portion 208A at the tip end is in constant contact with the cam 202A on the outer periphery of the turret plate 202, and swings in accordance with the rotation of the turret plate 202 (cam 202A). Accordingly, by detecting the swing angle of the lever member 208 (that is, that the roller portion 208A has reached the valley of the cam 202A), it is possible to detect that each color filter has been rotated to a predetermined position. . Further, when the roller portion 208A of the lever member 208 reaches the valley portion of the cam 202A, the turret plate 202 can be accurately positioned by the lever member 208 by making the rotation of the turret plate 202 free.

  FIG. 2 is a plan view of the main part of the turret plate 202, and FIG. 3 is a cross-sectional view taken along the line 3-3 in FIG.

  As shown in FIGS. 2 and 3, a support frame 212 is attached around the color filter 210, and the color filter 210 is held by the turret plate 202 with a predetermined play via the support frame 212. . That is, the color filter 210 can move in the direction of the optical axis L as shown in FIG. 3 and can be slightly tilted by play with the turret plate 202.

  On one surface (the left surface in FIG. 3) of the support frame 212 of the color filter 210, three convex portions 212A that define a plane are formed, and a plane defined by the three convex portions 212A. Are parallel to the plane of the color filter 210 which is a parallel plate. The support frame 212 is made of a magnetic material such as iron.

  As shown in FIG. 3, a positioning member 220 is disposed adjacent to the turret plate 202.

  The positioning member 220 has a reference surface 220 </ b> A facing the turret plate 202. The reference plane 220A is a plane orthogonal to the optical axis L, and is a plane parallel to the imaging plane of the monochrome imaging element 116 (see FIG. 4).

  In addition, three electromagnets 222 are embedded in the positioning member 220. In FIG. 3, only one electromagnet 222 is shown. When a current is passed through these electromagnets 222, the support frame 212 of the color filter 210 is attracted in the direction of the optical axis L by the magnetic action of the electromagnets 222, and the three convex portions 212A formed on the support frame 212 are respectively positioned members. 220 abuts on the reference surface 220A. Thereby, the surface of the color filter 210 is parallel to the reference surface 220 </ b> A of the positioning member 220.

  FIG. 4 is a block diagram showing an embodiment of the frame sequential color image pickup apparatus 10.

  As described above, the frame sequential color image capturing apparatus 10 includes the image capturing apparatus main body 100 and the rotating color filter apparatus 200. The frame sequential color image captured through the rotating color filter apparatus 200 is stored in a memory card. The operation of the entire apparatus is centrally controlled by a central processing unit (CPU) 140. The ROM 151 stores programs, adjustment values, and the like in advance, and these programs, adjustment values, and the like are read as appropriate.

  The imaging apparatus main body 100 is provided with an operation unit 138 including a shutter button and a mode dial for setting a shooting mode, a reproduction mode, and the like. A signal corresponding to an operation on the operation unit 138 is input to the CPU 140. .

  Image light indicating a subject is imaged on a light receiving surface of a black and white image sensor 116 such as a CCD image sensor or a CMOS image sensor via a rotating color filter device 200, a photographing lens 112, and a diaphragm 114.

  The turret plate 202 of the rotating color filter device 200 is rotationally driven by a filter driving unit 137 and a motor 204 controlled by the CPU 140 so that each color filter is positioned on the optical axis of the photographing lens 112 for each frame sequential photographing. Be controlled. In addition, the electromagnet 222 is driven for each frame-sequential shooting through the electromagnet driving unit 139 controlled by the CPU 140, and the support frame 212 of the color filter 210 is attracted so as to come into contact with the reference surface 220A of the positioning member 220.

The photographing lens 112 is driven by a lens driving unit 136 controlled by the CPU 140, and focus control and the like are performed. Aperture 114, for example, a five diaphragm blades, driven by a diaphragm driver 134 which is controlled by the CPU 140, for example, is controlled diaphragm 5 stage 1A _V increments until the aperture value F2.8 ~F11.

  In addition, the CPU 140 controls the diaphragm 114 via the diaphragm driving unit 134 and controls the charge accumulation time (shutter speed) in the monochrome image sensor 116 via the image sensor control unit 132.

  The signal charge accumulated in the monochrome image sensor 116 is read out as a voltage signal corresponding to the signal charge based on the readout signal applied from the image sensor control unit 132. The voltage signal read from the black and white image sensor 116 is applied to the analog signal processing unit 118, where the voltage signal for each pixel is sampled and held, amplified, and then applied to the A / D converter 120. The A / D converter 120 converts sequentially input analog signals into digital signals, and the digital signals (image data) are temporarily stored in a memory (SDRAM) 148 via the image input controller 122.

  The image data stored in the memory 148 is output to the VRAM 150 after required signal processing is performed via the digital signal processing unit 124. The VRAM 150 includes an A area and a B area each storing image data representing an image for one frame. In the VRAM 150, image data representing an image for one frame is rewritten alternately in the A area and the B area. The written image data is read from an area other than the area where the image data is rewritten out of the A area and B area of the VRAM 150. The image data read from the VRAM 150 is encoded by the video encoder 128 and output to the liquid crystal monitor 130 provided on the back of the camera, whereby the subject image is displayed on the display screen of the liquid crystal monitor 130.

  Further, when the shutter button of the operation unit 138 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 120 is taken into the AF detection unit 142 and the AE detection unit 144. The AF detection unit 142 uses image data (for example, a signal in the center region (focus region) of the monochrome image sensor 116), 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 140. The AE detection unit 144 integrates image data of the entire screen, or integrates image data with different weights at the center and peripheral portions of the screen, and outputs the integrated value to the CPU 140.

  Based on the AF evaluation value input from the AF detection unit 142, the CPU 140 moves the taking lens 112 to the lens position where the AF evaluation value is maximized via the lens driving unit 136, and the integration input from the AE detection unit 144. The brightness of the subject (shooting Ev value) is calculated from the value, and the aperture value of the diaphragm 114 and the electronic shutter (shutter speed) of the black and white image sensor 116 are determined based on the shooting Ev value according to a predetermined program diagram. Based on the determined aperture value, the aperture 114 is controlled via the aperture drive unit 134, and the charge accumulation time in the monochrome image sensor 116 is controlled via the image sensor control unit 132 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 It is temporarily stored in the memory 148 via the input controller 122.

  The digital signal processing unit 124 performs predetermined signal processing such as offset control, gain control processing including white balance correction and sensitivity correction, gamma correction processing, YC processing, and the like on the image data stored in the memory 148. The YC-processed image data (YC data) is read from the digital signal processing unit 124 and stored in the memory 148 again. Subsequently, the YC data is output to the compression / decompression processing unit 126, and a predetermined compression process such as JPEG (joint photographic experts group) is executed. The compressed YC data is again output to and stored in the memory 148, read by the media controller 152, and recorded on the memory card 154.

  When RAW data recording is performed, image data stored in the memory 148 via the image input controller 122 (frame sequential image data not subjected to signal processing in the digital signal processing unit 124). Is recorded in the memory card 154 as it is.

  Next, a procedure for capturing a frame sequential color image will be described with reference to a flowchart shown in FIG.

  In FIG. 5, first, a current is passed through the electromagnet 222 via the electromagnet drive unit 139 controlled by the CPU 140 (the electromagnet 222 is turned on) (step S10). As a result, as shown in FIG. 3, the support frame 212 of the color filter 210 held by the turret plate 202 is attracted by the electromagnet 222, and the three convex portions 212 </ b> A formed on the support frame 212 become the positioning member 220. The surface of the color filter 210 is parallel to the reference surface 220A. That is, the tilt of the color filter 210 with respect to the photographing optical axis can be corrected. It is assumed that one of the color filters is positioned on the photographing optical axis while the turret plate 202 is stopped.

  Subsequently, the subject is imaged (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, the electromagnet 222 is turned off, and the turret plate 202 is allowed to rotate (step S14).

  Thereafter, it is determined whether or not the imaging of all the color surfaces has been completed (step S16). If the imaging is completed, the imaging operation of the surface sequential color image is terminated, while the imaging of all the color surfaces is completed. If is not completed, the process proceeds to step S18.

  In step S <b> 18, the CPU 140 supplies driving power to the motor 204 via the filter driving unit 137 to drive the turret plate 202 to rotate (turns the motor 204 ON). Then, with the rotation of the turret plate 202, it is determined whether or not the next color filter has moved on the photographing optical axis (step S20). When the next color filter has moved on the photographing optical axis, the motor 204 is turned on. It is turned off (step S22). When the rotation of the turret plate 202 is stopped, the process returns to step S10, and the electromagnet 222 is turned on again.

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

  In this embodiment, the color filter is urged so as to contact the reference surface of the positioning member by the magnetic force of the electromagnet. However, the present invention is not limited to this, and the color filter is urged by the suction force of the vacuum means. The color filter may be biased so as to abut on the reference surface. In short, any color filter that moves on the photographing optical axis can be pressed against the reference surface of the positioning member.

  FIG. 6 is a cross-sectional view of an essential part showing another embodiment of the field sequential color image pickup apparatus according to the present invention. In addition, the same code | symbol is attached | subjected to the part which is common in sectional drawing shown in FIG. 3, and the description is abbreviate | omitted.

  As shown in FIG. 6, the color filter 210 is held on the turret plate 202 ′ with a predetermined play via a support frame 212 ′ attached around the color filter 210, and the support frame 212 ′ and the turret plate 202 ′. A coil spring 214 is disposed between them.

  Due to the biasing force of the coil spring 214, the color filter 210 is constantly biased toward the positioning member 220 ′.

  The color filter 210 moved to the photographing optical axis L by the rotation of the turret plate 202 ′ is formed on the support frame 212 ′, and the three convex portions 212A abut on the reference surface 220A of the positioning member 220 ′. Thus, the position of the surface of the color filter 210 in the photographing optical axis direction and the tilt with respect to the photographing optical axis are corrected.

FIG. 1 is an external view showing an embodiment of a frame sequential color image pickup apparatus according to the present invention. FIG. 2 is a plan view of the main part of the turret plate in the rotary color filter device shown in FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. FIG. 4 is a block diagram showing an embodiment of the frame sequential color image pickup apparatus shown in FIG. FIG. 5 is a flowchart showing an imaging procedure in the frame sequential color image imaging method according to the present invention. FIG. 6 is a cross-sectional view of an essential part showing another embodiment of the field sequential color image pickup apparatus according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Frame sequential color image imaging device, 20 ... Support stand, 100 ... Imaging device main body, 112 ... Shooting lens, 116 ... Monochrome imaging device, 200 ... Rotation color filter device, 202, 202 '... Turret plate, 203 ... Support shaft 204, motor, 210, color filter, 212, 212 ′, support frame, 212A, convex portion, 214, coil spring, 220, 220 ′, positioning member, 220A, reference surface, 222, electromagnet.

Claims (5)

Using a field sequential color image pickup device comprising a monochrome image pickup means, a color filter of at least three primary colors, a filter drive means, and a filter urging means, the color of the color filter is switched and a subject is picked up by the monochrome image pickup means. In an imaging method of a frame sequential color image that captures and acquires frame sequential color image data,
By the central processing unit by driving the filter drive means, a first step of sequentially moving each color filter on the imaging optical axis of the monochrome image pickup means,
When the color filter of any color is moved on the photographing optical axis of the black and white image pickup means by the first step, the central processing unit operates the filter urging means and the photographing light of the black and white image pickup means. A second step of urging the color filter moved on the axis in the direction of the optical axis and bringing it into contact with a reference plane parallel to the imaging plane of the monochrome imaging means;
Look including a third step of performing imaging by the monochrome image pickup means under the control of the central processing unit after the color filter is in contact with the reference surface,
The first step, the second step, and the third step are sequentially repeated until imaging of all color planes is completed under the control of the central processing unit. Method. A black-and-white imaging means, a color filter means having color filters of at least three primary colors, each color filter being sequentially switched and arranged on the photographing optical path of the black-and-white imaging means, and the color filter means and the monochrome imaging means when imaging a subject A field sequential color image capturing apparatus including an image capturing control means for controlling the image capturing to acquire the field sequential color image data,
The color filter means includes
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;
Filter driving means for driving the filter holding member to move each color filter onto the photographing optical axis of the black and white imaging means;
Filter urging means for bringing the filter moved on the photographing optical axis of the black and white imaging means by the filter driving means into contact with the reference surface of the positioning member;
A field-sequential color image pickup apparatus comprising:   The filter holding member is formed of a substantially circular turret plate rotatably disposed in front of the photographing optical system of the black and white imaging unit, and the filter driving unit rotates the turret plate to rotate each color filter. The frame sequential color image capturing apparatus according to claim 2, wherein the field sequential color image capturing apparatus is moved on an optical axis of the photographing optical system.   The filter urging means includes an electromagnet or vacuum means for urging the color filter so as to abut on a reference surface of the positioning member, and the black and white when each color filter moves on the optical axis of the photographing optical system. 4. The field sequential color image pickup apparatus according to claim 2, further comprising a drive control unit that operates the electromagnet or the vacuum unit for a predetermined period including an imaging period of the imaging unit.   The filter urging means is a spring member that is built in the filter holding member and elastically urges each color filter held by the filter holding member with play in a direction in contact with the reference surface of the positioning member. The field sequential color image pickup apparatus according to claim 2 or 3,

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