JPH07284002A - High resolution display device - Google Patents

Abstract

PURPOSE:To let the pictures of first and second frames look shifted to an observer, to double display picture elements to the eye and to make possible high resolution display. CONSTITUTION:A control circuit 14 receives video signals from a video camera 10, generates control signals changing between the continuous first and second frames of the video signals and supplies them to a first picture shifter 16 in front of the video camera and a second picture shifter 18 in front of a display device 12. The first picture shifter sends the pictures of the object of the video camera to an image pickup target as they are during a first frame period and sends the pictures of the object to the image pickup target while shifting them for 1/2 picture element pitch in a vertical direction for instance in a second frame period. The display device alternately displays the mutually shifted pictures for respective frames. The second picture shifter lets the display pictures of the display device pass through as they are in the first frame period and lets them pass through while shifting them in a direction opposite to the shifting direction of the first picture shifter in the second frame period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high resolution display device for displaying a photographed image in high resolution.

[0002]

2. Description of the Related Art Generally, in order to display a high resolution image, a video camera having a high density image pickup device such as a CCD device and a display having a high density pixel are required. However, both such high density video cameras and displays are expensive. Therefore, conventionally, a display device has been considered in which the resolution is improved by using a video camera having a normal resolution.

FIG. 7 is a block diagram for explaining the principle of this display device. This device has a lens 102, a filter 104 which is a prism, and a CCD imaging target 106, which are sequentially arranged to face each other along an axis 100. The filter 104 can be driven by a mechanical driving mechanism 108 so as to be tilted at a specific angle with respect to the axis 100 as shown by a dotted line in the drawing. In the first state, where the plane of the filter 102 is perpendicular to the axis 100, the rays that have passed through the lens 102 travel straight through the filter 104, as shown by the incident ray 110 along the axis 100 in the figure.
Form an image on top. The first image detected by the CCD element is converted into an analog signal, converted into a digital signal by an analog / digital converter (hereinafter referred to as ADC) 112, and then supplied to the signal processing unit 114. The signal processing unit 114 includes a central processing unit (hereinafter referred to as CPU), a frame memory, a digital-analog conversion circuit (hereinafter referred to as DAC) and related circuits, and the ADC 11
The digital signal supplied from 2 is stored in the frame memory.

Next, as described above, when the filter 104 is tilted by the specific angle θ with respect to the axis 100 by the driving mechanism as described above, the incident light ray 110 is refracted by the filter 104, and is incident on the imaging target 106. Distance D from the first image
The second image is formed at a position deviated by only this amount. The first and second images projected on the imaging target 106 are the same image except that the projection positions are different. By appropriately selecting the shift amount D between the first and second images in accordance with the distance between the CCD elements, the image portion that could not be detected by the CCD elements in the first state can be detected in the second state. First
Similar to the case of the state, the digital signal corresponding to the second image is stored in the frame memory in the signal processing unit 24. The first and second images stored in the frame memory are combined and read out as one image, converted into an analog signal by a DAC, and displayed on a display 116 such as a cathode ray tube at a frame frequency twice that of a normal one. The interlaced display makes it possible to display an image with improved resolution.

[0005]

However, in this apparatus, since the first and second images are obtained by controlling the tilt angle of the filter 104 by the mechanical driving mechanism as described above, the operation speed is slow and the displayed image is stationary. Limited to images. In addition, a large-capacity and expensive frame memory is required to store the first and second images at the same time. Furthermore, since a mechanical drive mechanism is used, the device becomes large, and the number of times of driving and the accuracy are limited.

Therefore, an object of the present invention is to use a CCD television camera and a display device having a normal resolution such as the NTSC system and to display a high resolution moving image without using a large capacity memory. In the provision of display devices.

[0007]

In the high resolution display device of the present invention, the control circuit receives a video signal such as the NTSC system from the video camera, and outputs a high level signal every one frame period of the video signal. A control signal having first and second frame periods alternating between low levels is generated and provided to a first image shifter located in front of the video camera. The first image shifter sends the image of the subject to the video camera as it is to the imaging target in the first frame period, and in the second frame period, the image of the subject is diagonally 1/2 1/2 of the 1/2 pixel pitch. The result is multiplied and multiplied and sent to the imaging target. The display alternately displays images that are displaced from each other for each frame. The second image shifter is
During the first frame period of the control signal, the display image of the display device is passed as it is, and during the second frame period, the same amount is passed in the direction opposite to the shifting direction of the first image shifter. As a result, for the observer, the images of the first and second frames are deviated by a predetermined amount, and the apparent display pixels are doubled to realize high resolution display.

[0008]

1 is a block diagram showing a schematic structure of a high resolution display device of the present invention. Video camera 10 having an imaging target composed of an imaging device such as a CCD device
Is an ordinary video camera that outputs a video signal such as the NTSC system, and the video signal is supplied to a display 12 such as a cathode ray tube or a liquid crystal display device. The control circuit 14 receives the video signal from the video camera 10 and generates a control signal composed of first and second frame periods which alternate between high level and low level for each frame period of the video signal, The first image shifter 16 arranged in front of the video camera 10 and the second image shifter 18 arranged in front of the display screen of the display 12 are supplied. Such control circuit 1
Reference numeral 4 denotes a video sync separator that generates an odd / even field signal whose level changes for each odd and even field from the video signal, and a frequency divider circuit that generates a control signal that divides the frequency of this output by half. It can be realized with.

The first image shifter 16 controls the video camera 10 during the first frame period of the control signal from the control circuit 14.
The image of the subject is passed through as it is, and the image of the subject is halved in the vertical or horizontal direction during the second frame period.
The pixel pitch or any one of the diagonal directions is shifted by 1/2 power of 1/2 pixel pitch and passed. Thereby, the imaging target of the video camera 10 can detect the pixel information which cannot be detected by being projected between the imaging elements in the first frame period in the second frame period. When the video signal obtained in this manner is displayed on the display 12, images shifted by a predetermined amount for each frame are alternately displayed.

The second image shifter 18 receives the first signal of the control signal.
During the frame period, the display image on the display 12 is allowed to pass through, and during the second frame period, the first image shifter 16 is allowed to pass with a 1/2 pixel pitch shift in a direction opposite to the image shifting direction. As a result, the images of the first and second frames appear to be shifted by a predetermined amount to the observer, and apparently the number of display pixels is doubled to realize high resolution display.

FIG. 2 is a block diagram showing the configuration of the apparatus shown in FIG. 1 in more detail. The video camera 10 includes a lens 22 and an imaging target 24 arranged along an axis 20.
And a video signal generation circuit 26. Lens 22
Forms an image of the subject on the imaging target 24,
The video signal generation circuit 26 performs processing such as inserting horizontal and vertical synchronization signals into the electric signal extracted from the imaging target 24, and generates an NTSC video signal.

The first image shifter 12 includes a polarization filter 28, a liquid crystal cell 30, and a birefringent polarizer 32, which are sequentially arranged in front of the video camera 10 along the axis 20 passing through the center of the imaging target 24. Have. Polarizing filter 28
Is a light absorption axis 28 that forms an angle of 45 degrees with the horizontal direction.
a and a light transmission axis 28b, incident natural light is converted into polarized light having a vibrating surface in the direction of the light transmission axis 28b, and the light is emitted.

The liquid crystal cell 30 is a liquid crystal variable optical retarder that gives a retardation of zero to half wavelength to an incident light beam. The optical axis 30a of the liquid crystal cell 30 is arranged at an angle of about 45 degrees with respect to each polarization axis of the polarization filter 28, and is parallel to the horizontal direction here. The liquid crystal cell 30 is turned on during the first frame period of the control signal from the control circuit 14 and turned off during the second frame period. When the liquid crystal cell 30 is in the ON state, it does not retard the incident light beam, and the incident polarized light beam is emitted without changing the polarization direction. Further, the liquid crystal cell 30 gives a half-wave retardation to an incident light beam when in the off state,
The incident polarized light is emitted with its polarization direction rotated by 90 degrees. As the liquid crystal cell 30, a high speed operation can be obtained to some extent, the light transmittance is good, and the liquid crystal cell is inexpensive.
A liquid crystal cell commonly referred to as “π cell” described in detail in No. 196728 is suitable. Further, if high speed operation is required, a PLZT element may be used as a variable optical retarder.

The birefringent polarizer 32 is a single optical axis anisotropic crystal having a birefringent property such as calcite and quartz. The birefringent polarizer has an optical axis inclined with respect to the incident surface, and the optical axis 32a of the birefringent polarizer 32 has a projection on the incident surface parallel to the light absorption axis 28a of the polarization filter 28, and the axis 20 With respect to, the upper side is inclined toward the imaging target 24 side. When a natural ray is incident on the entrance surface of a birefringent polarizer at a right angle, an ordinary ray that advances straight in the principal plane determined by the optical axis of the polarizer and the traveling direction of the incident ray in the polarizer It is divided into extraordinary rays. The ordinary ray and the extraordinary ray are parallel to each other when passing through the polarizer, and therefore, when an object is viewed through the birefringent polarizer, it looks double. Further, when a polarized light ray is incident on the birefringent polarizer, depending on the relationship between the main surface determined by the traveling direction and the optical axis of the polarized light ray and the polarization direction of the polarized light ray,
Only one of the ordinary ray and the extraordinary ray is emitted.
If the polarization direction of the incident polarized light ray is perpendicular to the principal plane, the polarized light ray goes straight through the polarizer and is emitted as an ordinary ray. On the other hand, if the polarization direction of the incident polarized light beam is parallel to the optical axis of the polarizer, the polarized light beam is refracted in the polarizer and is emitted as an extraordinary light beam. The direction in which the extraordinary ray deviates from the ordinary ray depends on the inclination direction of the optical axis. In the birefringent polarizer 32, the extraordinary ray shifts diagonally to the upper left side with respect to the ordinary ray when viewed toward the imaging target 24. The amount of deviation depends on the material and thickness of the birefringent polarizer 32.

The CCD image pickup target 24 actually has several hundreds of thousands of CCD elements, but in FIG. 3, only four of these CCD elements 24a to 24c are included to simplify the explanation.
24d is shown. Here, each CCD element is represented by a square, and the element pitch is shown as being equal to the length of one side of each element. The row arrangement direction of the CCD elements is parallel to the horizontal direction and forms an angle of 45 degrees with each axis of the polarization filter 28. Further, the above-mentioned shift amount due to the birefringent polarizer 32 corresponds to 2 1/2 times the 1/2 pitch of the CCD element.

When the liquid crystal cell 30 is turned on, the polarized light beam that has passed through the light transmission axis 28b of the polarization filter 28 passes through the liquid crystal cell 30 without rotating its polarization direction and enters the birefringent polarizer 32. . Since the polarization direction of the polarized light ray is at right angles to the principal plane determined by the traveling direction of the polarized light ray and the optical axis 32a of the birefringent polarizer 32, the polarized light ray advances straight as the ordinary light ray in the birefringent polarizer 32 and the imaging target. Reach 24. That is, the image of the subject goes straight and is projected on the imaging target 24. The CCD elements 24a to 24d are
Pixel information 24a1, 24b1, 24 projected on it
c1 and 24d1 are detected. The pixel information detected by the imaging target 24 is converted into an electric signal and sent to the video signal generation circuit 26. The video signal generation circuit 26 is
The input electric signal is processed to generate and output a video signal for one frame.

Next, when the liquid crystal cell 30 is turned off, the polarized light beam that has passed through the light transmission axis 28b of the polarization filter 28 is rotated by 90 degrees in the polarization direction and then passes through the liquid crystal cell 30, and the birefringent polarizer 32 is provided. Incident on. Since the polarization direction of the polarized light ray is parallel to the principal plane determined by the optical axis 32a of the polarized light ray and the birefringent polarizer 32, the polarized light ray is refracted in the birefringent polarizer 32 as an extraordinary ray to the upper left side. The light is emitted from the birefringent polarizer 32 and reaches the imaging target 24. That is, the image of the subject is shifted to the upper left side obliquely as compared with when the liquid crystal cell 30 is in the ON state, and the imaging target 2
4 is projected. Therefore, in the ON state, the pixel information 24a2, 24b2, 24c2, and 24d2, which is projected on the obliquely lower right side of each CCD element and is not detected, is CC respectively.
The D elements 24a, 24b, 24c, and 24d can be detected. In this way, the pixel information detected by the imaging target 24 is similarly converted into an electric signal and then output from the video signal generation circuit 26 as a video signal for one frame.

As described above, from the video signal generation circuit 28, the first frame signal including the pixel information 24a1, 24b1, 24c1 and 24d1 of the subject and the pixel information at the position surrounded by the pixel information included in the first frame. 24a2,
A video signal including a second frame signal including 24b2, 24c2 and 24d2 is supplied to the display 12.
The display unit 12 displays corresponding pixel information of the first and second frames on the same display dot, for example, 24a1 and 24a2.
Are displayed alternately.

The second image shifter 18 is arranged in front of the display screen of the display 12 so as to sequentially face the display 12 along the axis 34 passing through the center of the display screen.
6, a liquid crystal cell 38, and a birefringent polarizer 40. The polarization filter 36, like the polarization filter 28, forms a light absorption axis 36 a and a light transmission axis 3 that form an angle of 45 degrees with the horizontal direction.
6b. The liquid crystal cell 38 is a liquid crystal optical retarder similar to the liquid crystal cell 30, and its optical axis 38a is arranged in a relation of approximately 45 degrees with respect to each polarization axis of the polarization filter 36, and is parallel to the horizontal direction here. . The liquid crystal cell 38 is
The first control signal from the control circuit 14 together with the liquid crystal cell 30
It is turned on during the frame period and turned off during the second frame period.

The birefringent polarizer 40 is a birefringent polarizer similar to the birefringent polarizer 32. Optical axis 4 of birefringent polarizer 40
0a is such that the projection on the incident surface is parallel to the light absorption axis 36a of the polarization filter 36, and the upper side of the axis 34 is the display 12.
Inclined to the side. In the birefringent polarizer 40, the display 12
The extraordinary ray of the ray from is shifted to the lower left side in the traveling direction with respect to the ordinary ray. That is, when looking toward the screen of the display device 12, it shifts to the lower right side.

During the first frame period of the video signal, when the liquid crystal cell 38 is in the ON state, the polarization direction of the polarized light beam emitted from the display screen of the display 12 and passing through the light transmission axis 36b of the polarization filter 36 is rotated. Liquid crystal cell 38 without
And enters the birefringent polarizer 40. Since the polarization direction of the polarized light ray is at right angles to the principal plane determined by the traveling direction of the polarized light ray and the optical axis of the birefringent polarizer 40, the polarized light ray goes straight through the birefringent polarizer 40 as an ordinary ray and is emitted. , Observed by the observer.

During the second frame period of the video signal, when the liquid crystal cell 38 is in the off state, the polarized light emitted from the display screen of the display 12 and passing through the light transmission axis 36b of the polarization filter 36 has a polarization direction of 90 degrees. It is rotated, passes through the liquid crystal cell 38, and enters the birefringent polarizer 40. Since the polarization direction of the polarized light ray is parallel to the principal plane determined by the traveling direction of the polarized light ray and the optical axis of the birefringent polarizer 40, the polarized light ray is refracted in the birefringent polarizer 40 to the lower left side in the traveling direction. It is emitted and observed by an observer. That is, from the observer to the display 12
When viewing the screen, the pixels of the second frame appear to be shifted to the lower right side with respect to the corresponding pixels of the first frame. Thereby, the pixel information (including 24a1 to 24d1) of the first frame detected on the imaging target 24 and the pixel information (including 24a2 to 24d2) of the second frame located on the lower right side of this pixel information ( An image consisting of (see FIG. 3) is observed by the observer. This image has a larger number of apparent pixels in the horizontal and vertical directions, and the resolution is improved in both the horizontal and vertical directions, as compared with an image by a normal method. However, the first and second normal video signals
Since one frame of high resolution, that is, one frame is formed by the frames, the display frame frequency is halved.

In the apparatus shown in FIG. 1, the display 12 which is a CRT, a liquid crystal display or the like is directly viewed, but a projection type, that is, a projector is used as the display 12, and a display image is displayed. You may project on a screen through a lens. In practice, it is difficult to obtain a large size birefringent polarizer, and in the case of the direct view type, the size of the screen of the display 12 is limited. Therefore, by adopting the projection format, a high resolution image can be observed on a large screen.

When color high-resolution display is performed according to the present invention, the basic structure is the same as that shown in FIG. 1, except that the video camera 10 and the display 12 are replaced by a color display.
A video camera 10 'and a display 12' are used. Figure 5
Shows an example of the image pickup section of the color video camera 10 '. This camera 10 is a three-plate color camera, in addition to the usual structure consisting of red, green and blue imaging targets 52, 54 and 56 and prisms 64, 66 and 68, in front of the imaging targets 52, 54 and 56. The first image shifter 58 for red, the first image shifter 60 for green, and the first image shifter 62 for blue, which are arranged in These image shifters 58 to 62 are controlled by the control signal at the same time, and as shown in FIG. 3, the images projected on the imaging targets 52 to 56 in the second frame period are compared with the images in the first frame period. Shift.

FIG. 6 shows a display state when an aperture grill type color CRT called a Trinitron (registered trademark of Sony Corporation) tube is used as the color display 12 'in the present invention. As described above, the indicator 12 '
When viewing the screen, the pixels of the second frame appear to be shifted to the lower right side with respect to the corresponding pixels of the first frame. This improves the horizontal and vertical resolution. It should be noted here that the display pixels of the second frame are overlapped with the stripes of the aperture grille in the image of the first frame due to the shift of the display pixels by 1/2 pixel pitch in the horizontal direction. Of the aperture grille and the display dots of the first frame in the image of (1 pixel is 3 of R, G and B in this case).
Formed by one display dot). This gives a visual
The stripes on the aperture grille are countered by the display dots, making them almost inconspicuous. The same result can be obtained in a color liquid crystal display device such as a TFT system in which the R, G and B display elements are arranged in a line at a distance.

In the above description, the images of the first and second frames are shifted in the diagonal direction, but they may be shifted in the vertical or horizontal direction to improve the resolution in only one of the vertical and horizontal directions, respectively. Further, although the image shift of each frame of the video signal is performed, the horizontal resolution can be improved by shifting the even field and the odd field of the video signal obtained from the video camera 10 in the horizontal direction. However, in the image shifting in field units, the shifting direction is limited to the horizontal direction.

Although one embodiment of the present invention has been described above, it will be apparent to those skilled in the art that various modifications can be made without departing from the gist of the present invention. Image shifter 16
Although it is placed in front of the video camera 10, it may be placed between the lens 22 and the imaging target 24. Also, in each image shifter, the same result can be obtained even if the positions of the polarization filter and the birefringent polarizer are exchanged. Furthermore, FIG.
When the relationship between each axis of the polarizing filter and the birefringent polarizer is rotated by 90 degrees, the image shifts when the liquid crystal cell is on and the image goes straight when the liquid crystal cell is off.

The video camera 1 is displayed on the display 12, 12 '.
The output video signal of the video camera 10 is recorded on a video tape recorder (VTR), a laser disk, etc. without directly using the video signal from 0, 10 ', and the VTR is recorded.
May be supplied to the indicators 12, 12 ′ and the control circuit 14.

[0029]

According to the present invention, a moving image can be displayed in high resolution without using a large capacity memory by using a television camera and a display device having a normal resolution such as the NTSC system.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a high resolution display device of the present invention.

FIG. 2 is a block diagram showing the apparatus of FIG. 1 in detail.

FIG. 3 is a simplified diagram showing a relationship between an imaging target and detection pixel information.

FIG. 4 is a simplified diagram showing scan lines on a display.

FIG. 5 is a simplified diagram showing an image pickup section of a three-plate color camera used for color display by the apparatus according to the present invention.

FIG. 6 is an explanatory view showing a display state when an aperture grill type color CRT is used in the present invention.

FIG. 7 is a block diagram showing a conventional high resolution display device.

[Explanation of symbols]

 10 Video Camera 12 Display 14 Controller 16 First Image Shifter 18 Second Image Shifter 24 Imaging Target 28 First Polarization Filter 36 Second Polarization Filter 30 First Variable Optical Retarder 38 Second Variable Optical Retarder 32 First Birefringent Polarizer 40 Second Birefringent Polarizer

Claims (6)

[Claims] 1. A display unit, an imaging target, a video signal generation circuit for generating a video signal from an electric signal obtained from the target, a first continuous video signal for receiving the video signal.
And a control circuit for generating a control signal that changes between the second image and the image pickup target and the display, respectively. The control circuit is switched to the first and second control states according to the control signal, and the incident light beam is changed. The vibration surface of the
1st and 2nd, which is rotated by 2 degrees and is not rotated in the 2nd control state
A variable optical retarder; a first polarizing filter arranged on the side of the imaging target or on the opposite side of the first variable optical retarder to polarize an incident light beam in one direction; The first birefringent polarizer disposed on the opposite side of the first polarizing filter and having an optical axis in a predetermined direction with respect to the polarization direction of the first polarizing filter; and the second variable optical retarder, the indicator. On one side or on the other side, which polarizes the incident light in one direction
A polarization filter and a second birefringent polarization disposed on the opposite side of the second polarization filter with respect to the second variable optical polarizer and having an optical axis in a predetermined direction with respect to the polarization direction of the second polarization filter. A high resolution display device characterized by comprising a child. 2. A surface formed by the optical axis of the first and second birefringent polarizers with a traveling direction of an incident light ray is the first surface, respectively.
The high-resolution display device according to claim 1, wherein the high-resolution display device is perpendicular or parallel to the polarization direction of the second polarization filter. 3. The high resolution display device according to claim 1, wherein the birefringent polarizer is a single optical axis anisotropic crystal. 4. The high resolution display device according to claim 1, wherein the first and second images are images of two consecutive frames, respectively. 5. The high resolution display device according to claim 1, wherein the first and second images are images of consecutive odd and even fields, respectively. 6. The high resolution display device according to claim 1, wherein the display is an aperture grill type color cathode ray tube or a TFT type color liquid crystal.