JPH07284113A - High resolution color display device - Google Patents

Abstract

PURPOSE:To make the horizontal resolution thrice by arranging an image shift device in front of a display screen of a display device forming each color display picture element. CONSTITUTION:An image shift device 24 comprising a polarized light filter 14, a liquid crystal cell 16, a dual refraction polarizer 18, a liquid crystal cell 20 and a dual refraction polarizer 22 arranged in this order from a display device 12 along an axis 10 passing through a center of a display image is arranged in front of a display screen 12a of the display device 12. Then the 1st and 2nd liquid crystal cells 16, 20 are controlled respectively by 1st and 2nd control signals, and the image shift device 24 does not shift the display image for a 1st frame period, shifts the display image by one pitch of a display dot horizontally for a 2nd frame period and shifts the display image by two-pitch of a display dot horizontally for a 3rd frame period. Thus, display dots in R,G,B used to display the same picture element are displayed in order and a color display picture element is formed in the unit of displayed dots at the apparent same display dot position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high resolution color display device.

[0002]

2. Description of the Related Art Conventionally, a color cathode ray tube (hereinafter referred to as a CRT) which has been put into practical use usually employs a shadow mask as a color selecting mechanism. With this color selection mechanism,
By passing the electron beams for red (R), green (G) and blue (B) through the holes of the shadow mask, they collide with the red, green and blue phosphors formed on the phosphor screen, respectively, to display a color display. To do. The shadow mask, when called an aperture grill, is classified into a shadow mask provided with stripe-shaped holes and a shadow mask provided with dot- or slot-shaped holes. Generally, the former CRT using a shadow mask is called a Trinitron (registered trademark of Sony Corporation) type CRT, and the latter CRT using a shadow mask is simply called a shadow mask type CRT. In the Trinitron type CRT, the electron beams for three colors are arranged inline in the lateral direction (linear shape), and the phosphors of the three colors are formed in stripes in the vertical direction. In the shadow mask type CRT, there are two types of electron beams for three colors arranged inline in the lateral direction and ones arranged in delta (triangular shape). Depending on the arrangement direction, three colors of fluorescent light are emitted on the fluorescent screen. The body dots are arranged in line or in a delta.

Further, in the color liquid crystal display device, color filters for R, G and B are arranged on display dots arranged in the horizontal direction, and color display is performed by using a liquid crystal shutter.

[0004]

In any of these color display devices, one color display pixel is formed by display dots of three colors. Therefore, the resolution of the color display device is lower than that of a monochrome display device that forms one display pixel with one display dot.

Therefore, an object of the present invention is to provide a high resolution color display device which can obtain a resolution equivalent to that of a monochrome display device.

[0006]

In the high resolution color display device of the present invention, display dots of R, G and B are arranged in order in the horizontal direction to form each color display pixel. An image shifter is placed in front. The image shifter includes a polarizing filter arranged in order, a first liquid crystal cell,
It comprises a first birefringent polarizer, a second liquid crystal cell and a second birefringent polarizer. In response to the vertical synchronizing signal of the video signal supplied to the display, the control circuit changes the state for each frame period with the continuous first, second and third frame periods of the video signal as one cycle. First and second control signals are generated and supplied to the first and second liquid crystal cells, respectively, to control the on and off states of the liquid crystal cells. The frame buffer memory stores color pixel information for forming an image having three times the number of pixels in the horizontal direction with respect to the number of display pixels of the display device, and reads out the color pixel information to convert it into an analog signal to convert a video signal. Generate and supply to the display. The same R, G, and B display dots on the line on the screen should be horizontally adjacent to each other.
The R, G, and B display dot data of one color display pixel are sequentially assigned to the first, second, and third frame periods, respectively. The first and second liquid crystal cells are controlled by the first and second control signals, and the image shifter does not shift the display image in the first frame period, and displays the display image in the second frame period by one pitch of the display dot. The display image is shifted in the horizontal direction, and the display image is shifted in the same direction by two pitches of display dots in the third frame period. As a result, R, G, and B display dots for displaying the same pixel are sequentially displayed at the apparently same display dot position, and a color display pixel can be formed in display dot units.

[0007]

1 is a block diagram showing the structure of a high resolution color display device of the present invention. Display screen 1 of display 12
In front of 2a, a polarization filter 14, a liquid crystal cell 16, a birefringent polarizer 18, a liquid crystal cell 20 and a birefringent polarizer 22 which are sequentially arranged from the display 12 side along an axis 10 passing through the center of the display screen. An image shifter 24 including is arranged. The display device 12 is a color display device such as a trinitron system CRT, an in-line array electron gun system CRT, and a color liquid crystal display device in which R, G, and B display dots are sequentially arranged in the horizontal direction to form each color display pixel. . Polarizing filter 14
Has a light absorption axis 14a in the horizontal direction and a light transmission axis 14b in the vertical direction, and converts incident natural light into a polarized light beam having a vibrating surface in the direction of the light transmission axis 14b and emits it.

The liquid crystal cells 16 and 20 are liquid crystal variable optical retarders that provide zero or half-wave retardation for incident light rays. The optical axes 16a and 20a of the liquid crystal cells 16 and 20 respectively form an angle of approximately 4 with respect to each axis of the polarization filter 14.
They are placed in a 5 degree relationship. The liquid crystal cells 16 and 20
Are controlled to be turned on or off by the first and second control signals from the control circuit 25, respectively. When the liquid crystal cell is in the ON state, it does not give retardation to the incident light,
The incident polarized light beam is emitted without changing the polarization direction. When the liquid crystal cell is in the off state, it imparts half-wave retardation to the incident light beam, and the incident polarized light beam is emitted with its polarization direction rotated by 90 degrees. Liquid crystal cell 16
For Nos. 20 and 20, a liquid crystal cell commonly referred to as "π cell" described in detail in JP-A No. 60-196728 is suitable because of high speed operation, good light transmittance, and low cost. Further, if high speed operation is required, a PLZT element may be used as a variable optical retarder.

The birefringent polarizers 18 and 22 are birefringent single-optical axis anisotropic crystals such as calcite and quartz.
The birefringent polarizer has an optical axis inclined with respect to the plane of incidence,
When a natural ray is incident on the incident surface at a right angle, it is divided into 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, and an extraordinary ray that advances by refraction. The ordinary ray and the extraordinary ray are parallel to each other when exiting from the polarizer, so that they appear double when an object is viewed through the birefringent polarizer. Further, when a polarized light ray is incident on the birefringent polarizer, only one of the ordinary ray and the extraordinary ray is generated, depending on the relationship between the traveling direction of the polarized light ray and the polarization direction of the polarized light ray with the principal plane determined by the optical axis. 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. Birefringent polarizer 1
The optical axes 18a and 22a of 8 and 22 are parallel to the optical absorption axis 14a of the polarization filter 14 when projected onto the incident surface, and
With respect to 0, the left side is inclined forward in the traveling direction of the light ray. Therefore, in the birefringent polarizers 18 and 20, the extraordinary ray shifts to the right side with respect to the ordinary ray when viewed from the observer. This amount of shift depends on the material and thickness of the birefringent polarizer, and here is equal to one pitch of the display dots that are adjacent in the horizontal direction.

The main memory 28 is a display list generated by a central processing unit (CPU) 30 using graphic design software stored in the main memory 28 in accordance with a command given from an input device 26 such as a keyboard and a mouse. I remember. The display list is, for example,
It includes data that determines the coordinates of the two end points for representing a straight line in the specific coordinates, and data that specifies various attributes such as the thickness and color of the straight line. Picture processor 32
Receives the display list from the main memory 28, processes it, generates pixel data and control data corresponding to each pixel on the screen of the display 12, and sends it to the frame buffer (FB) memory 34. The FB memory 34 has R, G, and B memories 34R, 34G, and 34B, and stores pixel data at an address determined by control data. The FB memory 3 is generated by the CPU 28 for high resolution display.
The number of pixel data stored in 2 corresponds to three times the number of displayable pixels of the display 12.

The FB memory 32 is controlled by the CPU 30.
R, G, and B digital pixel data are read from
It is supplied to a digital-to-analog converter (DAC) 36. The DAC 36 converts each digital pixel data into an analog signal and outputs R, G, and B component signals. The synchronization signal generation circuit 38 is the FB by the CPU 30.
Upon receiving a signal indicating the read timing of the memory 34, the horizontal synchronizing signal H and the vertical synchronizing signal V are generated in response thereto. The display 12 receives the three component signals and the horizontal and vertical synchronization signals H and V, and displays the display screen 12a.
Display the image on. The control circuit 25 receives the vertical synchronizing signal V and has three consecutive frame periods of the first and second frame periods.
And the third frame period is one cycle, and the first and second control signals are changed for each frame period. Liquid crystal cell 16
And 20 are both turned on during the first frame period, turned on and off during the second frame period, and turned off and on during the third frame period, respectively. The control circuit 25 can be composed of a counter of 3 counts for counting the vertical synchronizing signal and a read only memory for receiving the count value and outputting a predetermined 2-bit value.

The operation of the apparatus of the present invention will be described below. Here, one pixel data is assumed to consist of display dot data which is three brightness data of R, G and B. FIG. 2 shows R, G, and B memories 34R of the FB memory 34,
Stored in n addresses of 34G and 34B,
It represents display dot data for forming pixels on the first line of the display image, for example. The number of addresses n is equal to the number of display dots in one line. The display dot data stored at the address k of the R memory 34R, the address (k + 1) of the G memory 34G, and the address (k + 2) of the B memory 34B are used to form the same pixel (k Is an integer). These data are shown by attaching the same number after the letter R, G or B in FIG. Figure 3
Represents the read timing of the display dot data read from the R, G, and B memories 34R, 34G, and 34B in the first, second, and third frame periods. Also, FIG.
Represents the apparent position of the display dot when the observer views the display image on the display 12 during the first, second and third frame periods.

Referring to FIG. 3, at the time t1 of the first frame period, the dot data R1 and G2 from the address 1 of the R, G and B memories 34R, 34G and 34B, respectively.
And B3 are read. These brightness data are R, G and B at positions P1, P2 and P3 on the display screen 12a.
It is used to simultaneously emit the display dots of. Next, at time t2, dot data R2, G3, and B4 are read from address 4 of the R, G, and B memories, respectively,
It is used to emit the display dots at the positions P4, P5 and P6 on the display screen 12a. The dot data at the addresses (1 + 3k) of the R, G, and B memories are sequentially read and used to emit the display dots at the remaining positions P7 to Pn, and the first line of the first frame period is displayed. To be done.

In the first frame period, the liquid crystal cells 16 and 20 are both turned on by the first and second control signals. The polarized light beam that has passed through the light transmission axis 14 b of the polarization filter 14 passes through the liquid crystal cell 16 without rotating its polarization direction and enters the birefringent polarizer 18. Since the polarization direction of the polarized light beam is at right angles to the principal plane determined by the traveling direction of the polarized light beam and the optical axis 18a of the birefringent polarizer 18, the polarized light beam travels straight in the birefringent polarizer 18 as an ordinary ray and is emitted. Then
It is incident on the liquid crystal cell 20. The polarized light passes through the liquid crystal cell 20 without rotating the polarization direction, and the birefringent polarizer 2
Incident on 2. Similar to the birefringent polarizer 18, the polarized light beam goes straight through the birefringent polarizer 22 and exits. In this way, the first
In the frame period, the light beam from the display 12 goes straight through the image shifter 24, and the image on the screen is observed by the observer in the display position as shown in FIG.

At time t1 of the second frame period, R, G
And address B of memories 34R, 34G and 34B for B
The dot data R2, G3, and B4 are read from each. These luminance data are used to simultaneously cause the R, G, and B display dots at the positions P1, P2, and P3 on the display screen 12a to emit light. Similarly, the dot data at the addresses (2 + 3k) of the R, G, and B memories are sequentially read and used to emit the display dots at the remaining positions P4 to Pn, and the dot data of the second frame period. One line is displayed.

During the second frame period, the liquid crystal cells 16 and 20 are turned on and off by the first and second control signals, respectively. The polarized light beam that has passed through the light transmission axis 14 b of the polarization filter 14 passes through the liquid crystal cell 16 without rotating its polarization direction and enters the birefringent polarizer 18. Since the polarization direction of the polarized light beam is at right angles to the principal plane determined by the traveling direction of the polarized light beam and the optical axis 18a of the birefringent polarizer 18, the polarized light beam travels straight in the birefringent polarizer 18 as an ordinary ray and is emitted. Then, the light enters the liquid crystal cell 20. The polarized light beam has its polarization direction rotated by 90 degrees, passes through the liquid crystal cell 20, and enters the birefringent polarizer 22. 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 22a of the birefringent polarizer 22, the polarized light ray is an extraordinary ray in the birefringent polarizer 22, After being refracted to the right as viewed, the light exits from the birefringent polarizer 22. The amount of deviation due to this one-time refraction is equal to one pitch of the display dots adjacent in the horizontal direction as described above. Thus, in the second frame period, the light beam from the display 12 is shifted once in the image shifter 24, and the image on the screen 12a is changed as shown in FIG.
Observed by the observer with a pitch of one display dot shifted to the right from the display position, and the positions P1 to P (n− on the screen 12a are observed.
The display dots of 1) are apparently observed at the positions P2 to Pn, respectively.

At time t1 of the third frame period, R, G
And address B of memories 34R, 34G and 34B for B
The dot data R3, G4, and B5 are read out from each. These luminance data are used to simultaneously cause the R, G, and B display dots at the positions P1, P2, and P3 on the display screen 12a to emit light. Similarly, the dot data at the address 3k of the R, G, and B memories are sequentially read and used to emit the display dots at the remaining positions P4 to Pn, and the first line of the second frame period. Is displayed.

During the third frame period, the liquid crystal cells 16 and 20 are turned off and on by the first and second control signals, respectively. The polarization direction of the polarized light beam that has passed through the light transmission axis 14b of the polarization filter 14 is rotated by 90 degrees and the liquid crystal cell 1
After passing through 6, the light enters the birefringent polarizer 18. 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 18a of the birefringent polarizer 18, the polarized light ray is an extraordinary ray in the birefringent polarizer 18, The light is refracted to the right as viewed, passes through the birefringent polarizer 18, and enters the liquid crystal cell 20. Since the polarized light passes through the liquid crystal cell 20 without rotating the polarization direction, the polarized light is similarly refracted and emitted in the birefringent polarizer 22. As described above, in the third frame period, the light beam from the display device 12 is shifted twice by the image shifter 24, and as shown in FIG. 4, the image on the screen 12a has two pitches of display dots to the right of the display position. The positions P1 to P (n
The display dots of -2) are apparently observed at the positions P3 to Pn, respectively.

As shown in FIG. 4, in the first frame, the dot data Gm, B (m + 1) and R (m + 2) are assigned to the display dot positions, and in the second frame, the dot data Rm, G (respectively). Display dots to which m + 1) and B (m + 2) are allocated are observed, and dot data Bm, R (m + 1) and G (m + 2) in the third frame, respectively.
The display dots assigned are observed. Therefore, R, G, and B display dots for displaying the same pixel are sequentially observed at the apparently same display dot position, and a color display pixel can be formed in display dot units. As a result, the resolution in the horizontal direction is tripled as compared with the conventional case where one color display pixel is formed by the R, G and B display dots arranged in the horizontal direction using the conventional display. be able to. However, since one color image is generated in three frames, in order to prevent flicker, the horizontal and vertical sync frequencies are set to 3 for each.
It is desirable to double the frame frequency to triple the conventional frequency.

In the above description, the display 12 is described as a direct-viewing type display device, but a liquid crystal display for a projector may be used as the display and the display image may be projected on the screen. In practice, it is difficult to obtain a birefringent polarizer having a large size, and in the case of the direct view type, the size of the screen of the display 12 is limited. Therefore, by applying the present invention to a liquid crystal type projector using a small display,
You can observe high resolution images on a large screen.

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. For example, if the combination of the on and off states of the liquid crystal cells 16 and 20 is adjusted, the light absorption axis 14 of the polarization filter 14 is not parallel to the optical axes 18a and 22a of the birefringent polarizers 18 and 22 and is orthogonal. Good. In addition, the order of the components 14 to 22 of the image shifter 24 is displayed on the display unit 1.
It may be reversed with respect to 2. Further, if the reading order of the display dot data from the FB memory 34 is adjusted, the image shifter 24 can shift the image only on the left side or the left and right sides as viewed from the observer. For the left side only, the birefringent polarizers 16 and 20 are rotated 180 degrees about the axis 10 and the liquid crystal cells 16 and 2 are rotated as above.
0 is controlled, and in the case of both left and right sides, one of the birefringent polarizers 16 and 20 is rotated by 180 degrees, and the liquid crystal cells 16 and 20 are rotated.
Control appropriately.

[0022]

According to the present invention, R, G and B for displaying the same pixel at apparently the same display dot position.
Display dots are sequentially displayed, and color display pixels can be formed in display dot units. Compared with the conventional case where one color display pixel is formed by R, G, and B display dots arranged in the horizontal direction. Thus, the horizontal resolution can be tripled.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram showing display dot data stored in a frame buffer memory.

[Figure 3] Display dots from the frame buffer memory
FIG. 6 is a timing chart showing the timing of reading data.

FIG. 4 is an explanatory diagram showing apparent positions of display dots.

[Explanation of symbols]

 12 display means 14 polarization filter 16 first liquid crystal cell 18 first birefringent polarizer 20 second liquid crystal cell 22 second birefringent polarizer 24 image shifter 25 control circuit 34 memory means 36, 38 video signal generating means

Claims (2)

[Claims] 1. A display means for forming red, green, and blue display dots in a row to form each color pixel, a polarizing filter, a first liquid crystal cell, a first birefringent polarizer, and An image shifting unit having two liquid crystal cells and a second birefringent polarizer and arranged in front of the screen of the display unit, and for generating an image having three times as many pixels as the number of pixels of the display unit. Memory means for storing color pixel information of the above, video signal generating means for generating video signals of the first, second and third frames from the color pixel information read from the memory, receiving the video signal, Control means for generating first and second control signals for controlling the on and off states of the first and second liquid crystal cells for each of the first, second and third frames, respectively. And the third frame is adjacent To the red, green, and blue display dots of the image to be generated, the red, green, and blue display dot data of the adjacent display pixels of the image to be generated are respectively assigned, and the first and second liquid crystals are formed. The cell is controlled by the first and second control signals so that the image shifter shifts the display image for each frame, and red, green and blue display dots for apparently forming the same pixel on the same display dot. A high-resolution color display device capable of observing display dots to which data is assigned. 2. The polarization filter has a light transmission axis in one of a horizontal direction and a vertical direction, and projections of the optical axes of the first and second birefringent polarizers onto an incident surface are horizontal. High-resolution color display device described in.