JPH0713149A - Field sequential system color display - Google Patents

Abstract

PURPOSE:To obtain color reproducibility which is excellent for an image even when the electron beam of a CRT is driven at high speed. CONSTITUTION:The respective sections 13-1, 13-2, 13-3 and 13-4 of a color filter corresponding to divided liquid crystal cells can independently transmit the light of a specified color. At least a black-and-white picture display device 2 switching and displaying the component pictures of 1st, 2nd and 3rd colors, a color filter 13, and a color switching signal circuit generating color switching signals Y-1, Y-2, Y-3 and Y-4 for switching the color of the transmitted light of the color filter in accordance with the switching timing or the component picture in the black-and-white picture display device are provided. Then, the color switching signals Y-1, Y-2, Y-3 and Y-4 whose switching timing successively lags are inputted in the respective sections 13-1, 13-2, 13-3 and 13-4 of the color filter divided in a vertical direction on a display screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field sequential color display. More specifically, the present invention relates to a color filter for a field-sequential color display capable of obtaining good color reproducibility even at high speed drive, a method for driving the color filter, and a field-sequential color display using the color filter. Regarding

[0002]

2. Description of the Related Art A field-sequential color display is conventionally known as one of multi-color displays using liquid crystal cells. As shown in FIG. 3, such a field-sequential color display 1 is generally a monochrome CRT 2
And the like, and a color filter 3 provided on the front surface thereof. The color filter 3 includes a plurality of polarization filters 4a, 4b, 4c having different transmission wavelength characteristics.
And liquid crystal cells 5a and 5b provided between them. For example, as the first polarization filter 4a, one that transmits vertically polarized light of red (R) and horizontally polarized light of all colors of red (R), green (G), and blue (B) is provided, and the second polarization filter As 4b, provided is one that transmits vertical polarized light of all colors R, G, B and horizontal polarized light of G, and as the third polarization filter 4c, transmits vertical polarized light of B and horizontal polarized light of all colors of R, G, B. There is something to do. In addition, the liquid crystal cells 5a, 5
A π cell is provided as b.

According to such a color filter 3, 2
The two liquid crystal cells 5a and 5b are appropriately turned on or off.
By setting the state, the color filter 3 is changed to R, G,
It is possible to control so that either B or white light in which they are all mixed is transmitted. For example, if the liquid crystal cell 5a is
If n is set and the liquid crystal cell 5b is turned off, the vertical polarization of R and the horizontal polarizations of all colors of R, G, and B of the white light emitted from the CRT 2 are turned on by the first polarization filter 4a. The incident light is transmitted through the liquid crystal cell 5a without rotating the plane of polarization and enters the second polarization filter 4b. Then, the second polarization filter 4b is set to R
Vertically polarized light of G and horizontal polarized light of G are transmitted, and those lights are incident on the liquid crystal cell 5b in the off state, and the plane of polarization is 90 °.
The liquid crystal cell 4b is rotated and emitted, and the third polarization filter 4
incident on c. Then, only the horizontally polarized R light is emitted from the third polarization filter 4c.

Therefore, in the multi-color display 1 using such a color filter 3, as shown in FIG. 4, R, G,
The component images of the respective colors of B are switched and displayed. Further, a signal as shown in the figure is generated as a color switching signal Y for switching the transmitted light color of the color filter 3, and the transmitted light color of the color filter 3 is changed to R, G, B in synchronization with the switching timing of the video signal X. Make sure to switch in frame order. For example, while the electron beam of the CRT 2 scans from one end to the other end of the R screen (i) according to the video signal X, the color filter 3 transmits only the R light, and the electron beam of the CRT 2 is The color filter 3 transmits only G light while scanning the G screen (ii), and the color filter 3 transmits only B light while the electron beam scans the next B screen (iii). Then, in the same manner, the colors of light passing through the color filter 3 are switched to R, G, and B in a frame sequential manner in synchronization with the scanning of one screen by the electron beam. As a result, R, G,
Since the B color images are sequentially switched and emitted, a multicolor image is obtained due to the afterglow phenomenon in the retina of the human eye.

[0005]

However, in the conventional field-sequential color display 1, the electron beam of the CRT 2 sequentially scans the screen from the upper end to the lower end, but the color of the screen of the color display 1 is When the electron beam is driven at a high speed, a sufficient afterglow time cannot be secured below the screen of the color display 1 because the entire surface is switched immediately when it reaches the upper end of the screen, and therefore the original color cannot be reproduced. There was a problem. For example, at a certain time t1, the color filter 3 is designed to transmit R light, and the CRT2
Even when the color display 1 at the scanning portion starts emitting R light, the electron beam comes to the upper end of the screen at the next time t2 and the color filter 3
When the transmitted light of is switched to G light entirely, the lower end of the color display 1 which has just begun to emit R light is also switched to emit G light, so that a sufficient afterglow time of R light is secured. It is impossible to reproduce the original color in the image.

The present invention is intended to solve the problems of the prior art as described above, and it is an object of the present invention to provide good color reproducibility even in high-speed driving in a field sequential color display. To aim.

[0007]

The inventor has found that the above-mentioned object is to divide the color filter in the vertical direction and to sequentially shift the switching timings of R, G and B between the divided areas. The inventors have found that a sufficient afterglow time can be secured in any of the divided areas, and have completed the present invention.

That is, according to the present invention, in a color filter for a field-sequential color display comprising a plurality of polarizing filters having different transmission wavelength characteristics and a liquid crystal cell provided between the polarizing filters, the liquid crystal cells are arranged in the vertical direction of the display screen. Each of the divided liquid crystal cells can be independently driven, and light of a predetermined color can be independently transmitted in each area of the color filter corresponding to each of the divided liquid crystal cells. Provide a color filter that can.

In addition, as a method of driving such a color filter, at least a first color light, a second color light and a third color light are provided in each area of the color filter divided in the vertical direction of the display screen. The method for turning on and off each liquid crystal cell is provided so that the light of each color is sequentially switched and transmitted, and the switching timing of the light of each color is sequentially shifted between the areas of the adjacent color filters.

Further, in accordance with the black-and-white image display device for switching and displaying the component images of at least the first color, the second color and the third color, the color filter, and the switching timing of the component images in the black-and-white image display device. In a field-sequential color display equipped with a color switching signal circuit for generating a color switching signal for switching the transmitted light color of a color filter, the above-described color filter of the present invention is used as a color filter and is divided in the vertical direction of the display screen. Provided is a color display in which a color switching signal whose switching timing is sequentially shifted is input to each area of the color filter.

[0011]

In the color filter of the present invention, the liquid crystal cell is divided in the vertical direction of the display screen, and each liquid crystal cell is composed of an independently drivable area. This color filter is used in a field sequential color display. The color filter is driven according to the driving method of the present invention, and in that case, the transmitted light color of each area of the color filter is switched according to the switching timing of the component image of each color of the monochrome image display device. Then, from each area of the color filter divided in the vertical direction of the screen of the color display, at least the light of the first color (for example, R), the light of the second color (for example, G) and the third color (for example, The light of B) is sequentially switched and emitted, and the switching timing of each color of light between adjacent areas of the color filter is a black-and-white image table. While switching timing of each color component image of the device and have a fixed relationship, so successively shifted.
For example, at some point the CRT's electron beam begins to scan the bottom area of the display screen, the color filters in that area become transparent to R light, and at the next time the electron beam scans the top area of the display screen. First, even if the color filter in the upper end area is switched to transmit G light, the transmitted light of the color filter in the lower end area is not switched to G light at the same time as the color filter in the upper end area, and the electron beam is It can be R light until the bottom area is scanned. Therefore, even if the electron beam is driven at a high speed, it is possible to secure a sufficient afterglow time for each color in any part of the screen, and it is possible to reproduce the desired color in the image.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 2 is an explanatory diagram of the color display 11 according to the embodiment of the present invention. In the color display 11 of this embodiment, the monochrome CRT 2 and the polarization filters 4a, 4b and 4c of the color filter 13 are the same as those of the conventional example shown in FIG. 3, but the liquid crystal cell 5a of the color filter 13 is used. 5b is divided into four areas 5a-1 to 5a-4, 5b-1 to 5b-4 which can be driven independently in the vertical direction of the display screen, and the color filter 13 is also divided correspondingly. As shown in FIG. 1, it is composed of four sections 13-1 to 13-4. Also,
A color switching signal generating circuit for generating color switching signals Y-1, Y-2, Y-3, Y-4 for switching the transmitted light color of each area 13-1 to 13-4 of the color filter is provided. Are connected to the respective sections 13-1 to 13-4 (not shown).

The liquid crystal cells 5a and 5b thus divided.
Examples of the method for forming the
a-4, 5b-1 to 5b-4 may be separately formed and arranged in the vertical direction, or liquid crystal cells 5a, 5b
The transparent electrode of b may be formed from four parts that can be turned on and off independently.

In this embodiment, the liquid crystal cell is divided into four areas in the vertical direction, but the number of divisions of the liquid crystal cell is not limited to this. By increasing the number of divisions, it becomes possible to further support high-speed electron beam drive. However, if the number of divisions is too large, a plurality of areas of the color filter 13 corresponding to the finely divided liquid crystal cells enter the field of view at the same time, and a boundary line between areas having different color tones can be seen on one screen, which is not preferable. . Therefore, for example, when the scanning speed of the electron beam is about three times faster than the conventional one, it is usually preferable that the division number is 5 or less.

The color display 11 operates as shown in FIG. That is, the CRT 2 switches and displays the component images of each color of R, G, and B in the frame sequential manner by the video signal X, as in the conventional example shown in FIG. At this time, the color switching signals Y-1, Y-2, Y-3, and Y-4 are input to the color filters 13-1 to 13-4 in the respective areas as shown in the figure, which causes the color One area 13-1 of the filter is
The transmitted light color is switched in synchronization with the switching timing of the component image in the video signal X, and the transmitted light color switching timing is sequentially set between adjacent areas 13-1 to 13-4 including this area 13-1. It will shift. For example, at a certain time t1, the electron beam is below the R screen (i) (lower end area 1 of the color filter).
3-4), the entire area of the color filter 13-1 to 13-4
R light is emitted from the electron beam, and the electron beam is emitted from the G screen at the next time t2.
When the color filter 13 reaches the upper end (the upper end area 13-1 of the color filter) of (ii), only the upper end area 13-1 of the color filter 13 switches the transmitted light color so that the G light is emitted from the upper end area 13-1. Then, when the electron beam reaches the area 13-2 of the next color filter, the transmitted light color is switched only in the area 13-2, and the G light is emitted from the area 13-2. When the electron beam reaches the next area 13-3,
Only in the area 13-3, the transmitted light color is switched so that the G light is emitted from the area 13-3, and when the electron beam finally reaches the lower area 13-4, only the lower area 13-4. The transmitted light color is switched and G light is emitted from this area 13-4 as well. Hereinafter, similarly, the transmitted light color of each area of the color filter is sequentially switched to R, G, and B.

Thus, for example, at a certain time t1, the electron beam starts scanning the lower end area 13-4 of the color filter,
The R light is emitted from the lower end area 13-4, and at the next time t2, the electron beam comes to the upper end area 13-1 of the color filter and G light is emitted from the upper end area 13-1. Even if so, the R light still continues to be emitted from the lower end area 13-4 of the color filter. The R light from this bottom area 13-4 switches to G light the next time the electron beam begins scanning the bottom area 13-4 of the color filter. Therefore, a sufficient afterglow time is secured even in the lower end area 13-4, and the original color can be reproduced in the image.

In the above embodiment, the case where the light of each color of R, G, B is sequentially switched and emitted in each area of the color filter has been described.
It is also possible to provide white blanking that emits all colors of B or black blanking that does not emit any of R, G, and B. This makes it possible to improve the contrast of the screen.

[0019]

When the color filter of the present invention is used in a field sequential color display, it is possible to obtain good color reproducibility in an image even when the electron beam of a CRT is driven at high speed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an operation of a field sequential type color display according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a field sequential color display according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional field-sequential color display.

FIG. 4 is an explanatory diagram of an operation of a conventional field sequential color display.

[Explanation of symbols]

1 Conventional Field Sequential Color Display 2 Monochrome CRT 3 Conventional Color Filter 4a, 4b, 4c Polarizing Filter 5a, 5b Liquid Crystal Cell 5a-1 to 5a-4, 5b-1 to 5b-4 Liquid Crystal Cell 11 Field of Example Sequential system color display 13 Color filter 13 of the embodiment 13-1, 13-2, 13-3, 13-4 Areas of the color filter of the embodiment X video signal Y, Y-1, Y-2, Y-3, Y-4 color switching signal

Claims (3)

[Claims] 1. A color filter for a field-sequential color display comprising a plurality of polarizing filters having different transmission wavelength characteristics and liquid crystal cells provided between the polarizing filters, wherein the liquid crystal cells are divided in a vertical direction of a display screen. Further, a color filter capable of independently driving each of the divided liquid crystal cells and independently transmitting light of a predetermined color in each area of the color filter corresponding to each of the divided liquid crystal cells. 2. In each area of the color filter divided in the vertical direction of the display screen, at least the light of the first color, the light of the second color and the light of the third color are sequentially switched and transmitted, and 2. The method of driving a color filter according to claim 1, wherein each liquid crystal cell is turned on and off so that the switching timing of the light of each color is sequentially shifted between the areas of the adjacent color filters. 3. At least a first color, a second color and a third color.
Black and white image display device that switches and displays the component images of the
Claim: As a color filter in a field-sequential color display comprising a color filter and a color switching signal circuit for generating a color switching signal for switching the transmitted light color of the color filter in accordance with the switching timing of component images in a monochrome image display device. 1. A color display using the color filter according to 1, wherein a color switching signal whose switching timing is sequentially shifted is input to each area of the color filter divided in the vertical direction of the display screen.