JPH0832978A - Sequential plane color camera - Google Patents

Abstract

PURPOSE:To obtain a picked-up image of high quality with a simple device constitution by moving an image pickup element in the optical-axis direction to correct the deviation of the image forming position due to the chromatic aberration on the axis. CONSTITUTION:A camera control circuit 8 generates a moving signal for the purpose of moving an image pickup element 5 in the optical-axis direction of an arrow by colors and supplies this signal to an image pickup element moving part 6. Then, a prescribed voltage is supplied to a piezoelectric element, which moves the image pickup element 5, with respect to each color to control, the image pickup element 5 so that the image forming position of picture light of each color and the image forming face of the image pickup element 5 coincide with each other. The camera control circuit 8 stores data, which indicates a required magnitude of the moving signal for each color supplied to the image pickup element moving part 6, in a prescribed memory and reads out data in this memory to generate the image pickup element moving signal for each color.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame-sequential color camera, and more particularly to a frame-sequential color camera in which the adverse effect of axial chromatic aberration of an optical system is eliminated by moving an image pickup element in the optical axis direction.

[0002]

2. Description of the Related Art Conventionally, there is known a frame-sequential color camera in which image light of an object is color-separated by a color separation filter through an image pickup lens and then imaged by an image pickup device such as a CCD to obtain an image signal. In such a frame-sequential color camera, the color separation filter is provided with a color region for transmitting only light of each primary color, and the color separation filter is rotated to obtain image light of each primary color. However, since the image pickup lens generally has a different refractive index depending on the wavelength of incident light, an optical path difference and a focal position difference for each primary color occur depending on the wavelength of incident light. This is so-called axial chromatic aberration, and even in the case of the above-mentioned frame sequential color camera, there arises a disadvantage that the image forming plane of the subject image is displaced for each primary color.

Conventionally, in a frame-sequential color camera, in order to remove such axial chromatic aberration, it is known to perform correction by changing the thickness of the filter region for each primary color of the color separation filter (Japanese Patent Application Laid-Open No. Hei. 6-54331). That is, in this conventional frame-sequential color camera, the red (R) filter having a long wavelength is made thin, and the green (G) filter having a shorter wavelength is made thicker.
The focal position shift due to the wavelength of the incident light is corrected.

[0004]

However, in the conventional frame-sequential color camera as described above, it is necessary to manufacture a color separation filter having a filter area having a different thickness for each primary color. There is an inconvenience that it is difficult to manufacture a filter having a structure and the manufacturing cost is high. In addition, since the thickness of the filter differs for each primary color, the weight balance of the color separation filter becomes uneven, and it becomes difficult to drive the color separation filter to rotate at high speed. Therefore, such a structure enables high-speed shooting. It was difficult to realize such a frame sequential color camera.

The present invention has been made in view of the problems in the conventional camera as described above, and in the frame sequential color camera, the axial chromatic aberration of the optical system is accurately removed with a simple structure, so that a high quality image is obtained. It is to be able to obtain a color image.

[0006]

To achieve the above object, according to the present invention, a color separation filter for color-separating image light of an object to obtain image light of each primary color, and the color separation filter are used. In a field-sequential color camera having an image sensor that sequentially captures the obtained image light of each primary color and converts it into an electric signal, removes axial chromatic aberration for each color of the image light that has been color-separated by the color separation filter. In order to do so, a driving means for moving the image pickup device in the optical axis direction is provided for each color.

Conveniently, the driving means controls the movement of the image pickup device during a color mixing period in which the color boundary of the color separation filter passes on the image pickup screen of the image pickup device.

The driving means may be configured to determine the position of the image pickup device before the image pickup device starts image pickup of image light of each primary color.

The driving means is provided with a storage means for storing data indicating a movement amount or a position of the image pickup device calculated in advance, and when the image pickup device is moved based on the data stored in the storage means. It is convenient.

Further, the driving means may be composed of a piezoelectric element for moving the image pickup element.

[0011]

In the frame-sequential color camera having the above structure, the driving means moves the image pickup element in the optical axis direction according to each color of the image light color-separated by the color separation filter. This makes it possible to always match the image forming position of the image pickup optical system due to the axial chromatic aberration and the image pickup surface of the image pickup element. Therefore, the influence of the shift of the image forming position due to the axial chromatic aberration is removed, and a high quality captured image can be obtained.

Further, the driving means is arranged to control the movement of the image pickup device during a color mixing period in which the color boundary of the color separation filter passes on the image pickup surface of the image pickup device, thereby picking up image light of each color. Stable imaging is performed during the period.

If the drive means sets the position of the image pickup device before the image pickup device starts to pick up the image light of each primary color, the image pickup operation of each primary color is not adversely affected.

Further, more specifically, the driving means is provided with a storage means for storing data indicating a movement amount or a position of the image pickup element calculated in advance, and the image pickup element is based on the data stored in the storage means. By moving, it is possible to perform more accurate and precise control for each color. Further, the data stored in the storage means can be modified or switched as needed.

As the driving means, for example, a piezoelectric element for moving the image pickup element can be used,
This makes it possible to slightly displace the image sensor and accurately set its position.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic structure of a frame sequential color camera as an embodiment of a frame sequential color camera of the present invention. The camera shown in the figure includes a camera unit 20 and a frame memory unit 21. The camera section 20 includes an image pickup lens 1 that receives incident light from a subject (not shown), a color separation filter 2 that separates the image light that has passed through the image pickup lens 1, and a drive that rotationally drives the color separation filter 2. Part 3,
A rotation detection unit 4 for detecting the rotation phase of the color separation filter 2 is provided. The rotation detection unit 4 optically detects an origin position marker provided on the color separation filter 2 as described later, which is configured by a photo interrupter, for example.

The camera section 20 further includes an image pickup element 5 such as a CCD element, an image pickup element moving section 6 for moving the image pickup element 5 in the optical axis direction, and a predetermined image processing on a signal obtained from the image pickup element 5. It has a signal processing circuit 7 for performing the processing, and a camera control circuit 8 for controlling each unit of the camera unit 20.

Further, the frame memory unit 21 has an A / D conversion circuit 9, a memory control circuit 10, and an R image memory 11, a G image memory 12, and a B image memory each having a capacity capable of storing at least one field of image data. The image memory 13, the D / A conversion circuits 14, 15, 16 and the A / A converter
A switch unit 17 for sequentially switching and inputting the output of the D conversion circuit 9 to the memories 11, 12, and 13 is provided.
The output of such a frame memory unit 21 is connected to the monitor television 22.

FIG. 2 shows a detailed structure of the color separation filter 2 shown in FIG. The color separation filter 2 has color regions 23, 24, 25 that transmit only the primary colors R (red), G (green), and B (blue) on one disk and the rotational phase of the color separation filter. An origin position marker portion 26 including an opaque portion for detection is provided. This color separation filter 2
Is driven to rotate at a constant speed by the filter driving unit 3 in the direction indicated by the arrow A, and the origin position marker unit 26
Is detected by the detector 4 and an origin position signal is generated.
This origin position signal is sent to the camera controller 8, and as will be described in detail later, a color identification signal for identifying each color, a movement signal for moving the image sensor 5, and the like are generated. Note that, in FIG. 2, a dotted line portion 27 indicates an image pickup area by the image pickup element 7.

FIG. 3 shows how the image light formed by the image pickup lens 1 is image-formed after being color-separated by such a color-separation filter. That is, in general, the image forming point of the imaging lens 1 is at a different position due to the difference in the wavelengths of the R, G, and B primary color lights, which causes axial chromatic aberration. Of the R, G, and B primary color lights, the image light of R having the longest wavelength is located at the farthest point from the imaging lens 1, and the image light of B having the shortest wavelength is the closest to the imaging lens 1. Image in position. Therefore, according to the present invention, the image sensor 5 is used for capturing the image light R, G, B of each color.
Are moved in the optical axis direction by the image pickup device moving unit 6 and are controlled so that the image pickup surface of the image pickup device coincides with the image forming point of each image light.

The image pickup device moving section 6 is constructed by using a piezoelectric device 30 as shown in FIG. 4, for example. The piezoelectric element 30 shown in FIG. 4 is sandwiched between electrodes 32 and 33 in which a substance having a piezoelectric effect, for example, a piezoelectric substance 31 such as barium titanate is interleaved. By applying a voltage V between the electrodes 32 and 33, each piezoelectric substance expands or contracts, and therefore the total thickness of the piezoelectric element 30 expands or contracts in the direction indicated by the arrow in the figure. The amount of expansion or contraction of the piezoelectric element 30 can be set by adjusting the applied voltage. Therefore, it becomes possible to precisely move the image pickup device by using the piezoelectric element 30.

FIG. 5 shows a specific structure of the image pickup device moving section 6. 7A is a front view seen from the image pickup surface of the image pickup device 5, and FIG. 8B is a cross-sectional view taken along the line AA.

In such an image pickup device moving section 6, an image pickup device mounting plate 35 is mounted on a fixed base 34 via two piezoelectric devices 30. CCD on the image pickup device mounting plate 35
The image pickup device 5 as described above is adhered by, for example, an adhesive agent (not shown). Further, three guide pins 36 provided on the fixed base 34 penetrate through a guide hole 37 provided on the image pickup device mounting plate 35 to perform positioning in a direction perpendicular to the optical axis of the image pickup device 5. . In addition, the lead pins 38 of the image pickup device 5 are connected to an output board 39 formed of, for example, a flexible printed board.

The operation of the frame-sequential color camera having the above configuration will be described mainly with reference to FIG. In FIG. 1, incident light from a subject (not shown) passes through the image pickup lens 1 and the color separation filter 2 and is imaged on the image pickup surface of the image pickup device 5. The camera control circuit 8 in the camera unit 20 controls each unit based on the horizontal and vertical synchronization signals sent from the memory control circuit 10 of the frame memory unit 21. First, a predetermined control signal is input to the filter driving section 3 to rotate the color separation filter 2 at a constant speed. In response to the rotation of the color separation filter 2, the rotation detection unit 4 detects the origin position marker 26 (FIG. 2) on the color separation filter 2, generates an origin position signal, and inputs it to the camera control circuit 8. The camera control circuit 8 controls the number of revolutions of the color separation filter 2 to be a predetermined speed based on the origin position signal, and also generates a drive signal and a color identification signal for controlling the image pickup operation of the image pickup device 5. Supply. As a result, the image sensor 5 generates an image signal corresponding to the image light of the subject and inputs it to the signal processing circuit 7. After the signal processing circuit 7 performs predetermined image processing such as white balance adjustment, clamp, and gamma correction on the image signal input from the image sensor 5 using the color identification signal input from the camera control circuit 8 and the like. It is supplied to the frame memory unit 21.

As shown in FIG. 3, the camera control circuit 8 also generates a movement signal to the image pickup device moving unit 6 in order to move the image pickup device 5 for each color in the optical axis direction (arrow direction). Supply. As a result, a predetermined voltage for each color is supplied to the piezoelectric element (30, FIG. 4 and FIG. 5) for moving the image sensor 5, and the image forming position of the image light of each color and the image forming surface of the image sensor 5 are formed. Are controlled to match. The camera control circuit 8 stores in the ROM the data indicating the required magnitude of the movement signal supplied to the image pickup element moving unit 6 for each color.
Is stored in a predetermined memory, and the data in this memory is read for each color to generate an image sensor movement signal.

In the frame memory section 21, the image signal input from the signal processing circuit 7 of the camera section 20 is A /
The D conversion circuit 9 converts the digital signal, and the switch unit 17
Through the frame memories 11, 12,
Store in 13.

The digital image signals of the respective colors stored in the memories 11, 12 and 13 are read out at the same time and converted into analog signals by the D / A conversion circuits 14, 15 and 16, respectively, and the simultaneous analog RGB signals are obtained. Is supplied to the monitor television 22. Monitor television 22
From the memory control circuit 10 to the horizontal and vertical sync signals H
-Vsync is also supplied and an image is displayed.

In such an operation, the memory control circuit 1
0 accepts a color identification signal or the like sent from the camera control circuit 8 of the camera section 20, causes the switch section 17 to perform a switching operation based on these signals, and each memory 1
Data writing to 1, 12, 13 and each memory 1
The operation of reading data from 1, 12, 13 is controlled.

FIG. 6 schematically shows signal waveforms of various parts during the above operation. In the same figure, (A) schematically shows the picked-up video signal corresponding to the G, B, and R subject image lights color-separated by the color separation filter 2. Such a video signal is generated based on the origin position signal (B) shown in (B) (C),
Color identification signals (G-EN) of the respective colors shown in (D) and (E)
ABLE), (B-ENABLE), (R-ENABL
According to E), writing to each image memory of the frame memory unit 21 is performed.

Further, (F), (G) and (H) show position signals for controlling the position of the image pickup element 5 of each color. These position signals rise prior to the rise of the color identification signals (C), (D), (E) of the corresponding colors, so that at least the image pickup is performed prior to the acquisition of the video signal of each color and the writing to the image memory. The element 5 is configured so that it can be positioned at a predetermined position. In addition,
As the position signals (F), (G), (H), as described above, the data indicating the movement amount or the position of the image sensor 5 calculated in advance is stored in a memory such as a ROM, and It is generated by reading the data in the memory for each color. Further, by arranging the rising and falling points of each position signal during the color mixing period in which the color boundary of the color separation filter 2 passes through the image pickup area of the image pickup device, the influence of the movement of the image pickup device over the entire image pickup period of the image pickup device is affected. You can prevent it from reaching.

In the above embodiments, a disc-shaped color separation / rotation filter is used as the color separation filter. However, the color separation filter may be provided by other means such as a method of switching band-shaped filters. You may apply. In addition to the piezoelectric element, an electromagnetic actuator or the like may be used as a means for driving the image pickup element.

[0032]

As described above, according to the present invention, in the field-sequential color camera, the image pickup position is corrected by moving the image pickup element in the optical axis direction due to the axial chromatic aberration. It becomes possible to obtain an extremely high quality captured image with a simple device configuration. Further, as compared with the case where the thickness of each color region of the color separation filter is changed, the color separation filter can be easily manufactured and the increase in cost can be prevented. Furthermore, since the weight separation of the color separation filter does not become non-uniform, high-speed rotation driving is possible, and high-speed operation of the frame sequential color camera is easily possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a frame sequential color camera according to an embodiment of the present invention.

FIG. 2 is a front view showing a configuration of a color separation filter used in the frame sequential color camera of FIG.

FIG. 3 is an explanatory diagram showing a shift of an image forming point due to axial chromatic aberration for each color in the frame sequential color camera of FIG.

FIG. 4 is a principle explanatory diagram showing a configuration of a piezoelectric element used for moving an image pickup element in the frame sequential color camera of FIG. 1.

5 is a front view (a) showing a specific configuration of an image pickup device moving unit used in the frame sequential color camera of FIG. 1 and a sectional view (b) taken along line AA.

FIG. 6 is a schematic waveform diagram showing signals of respective parts of the frame sequential color camera of FIG.

[Explanation of symbols]

 1 Imaging Lens 2 Color Separation Filter 3 Color Separation Filter Driver 4 Rotation Detector 5 Image Sensor 6 Image Sensor Moving Unit 7 Signal Processing Circuit 8 Camera Control Circuit 9 A / D Conversion Circuit 10 Memory Control Circuit 11 R Memory 12 G Memory 13 B memory 14, 15, 16 D / A conversion circuit 17 switch section 20 camera section 21 frame memory section 22 monitor television 23, 24, 25 moving area 26 origin position marker 27 image pickup area 30 piezoelectric element 31 piezoelectric crystal 32, 33 electrode 34 fixing plate 35 mounting plate 36 guide pin 37 guide hole 38 output lead 39 output board

Claims (5)

[Claims] 1. A color separation filter for color-separating image light of an object to obtain image light of each primary color, and image light of each primary color obtained by the color separation filter are sequentially picked up and converted into electric signals. A field sequential color camera having an image pickup device for converting the image pickup device in the optical axis direction corresponding to each color in order to remove axial chromatic aberration of each color of the image light color-separated by the color separation filter. A field-sequential color camera having a driving unit for moving the frame sequential color camera. 2. The surface according to claim 1, wherein the driving unit controls the movement of the image pickup device during a color mixing period in which a color boundary of the color separation filter passes on an image pickup screen of the image pickup device. Sequential color camera. 3. The frame-sequential color according to claim 1, wherein the drive unit sets the position of the image pickup device before the image pickup device starts image pickup of image light of each primary color. camera. 4. The driving means comprises a storage means for storing data indicating a movement amount or a position of the image pickup element calculated in advance, and moves the image pickup element on the basis of the data stored in the storage means. The frame sequential color camera according to claim 1, wherein: 5. The driving means comprises a piezoelectric element for moving the image pickup element.
The frame sequential color camera described in.