JPH01158417A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To display a color image without using any color filter by driving an optical member with the synchronizing signal of an image signal and modulating and driving a light source with the brightness signal of said image signal. CONSTITUTION:A liquid crystal display 20 is supplied with a horizontal synchronizing signal H from a horizontal synchronizing circuit 32 through an oscillator and a shift register 33 and also with a vertical synchronizing signal V from a vertical synchronizing circuit 34 through an oscillator and a shift register 35. Thus, the vertical synchronizing signal V and horizontal synchronizing signal H are supplied to open and close dot optical shutters of the liquid crystal display 20 in order. Namely, when the shift register is put in operation with the vertical synchronizing signal V, LEDs in respective arrays illuminate according to a brightness signal Y. At this time, three primary color LEDs of red, green, and blue in each lateral array are modulated and driven in order to be projected on the liquid crystal display 20 according to the opening/closing operation of optical shutters. Consequently, the color image is displayed without using any color filter of complex structure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a liquid crystal display device, and particularly to a liquid crystal display device suitable for displaying various images on a liquid crystal display.

"Prior Art" Conventionally, a liquid crystal display device has the following characteristics, as shown in FIG.
A white light source 11 is disposed on the back side of the liquid crystal color display 10, and an image is displayed on the liquid crystal color display 10 by irradiating light from the white light source 11.

The liquid crystal color display 10 is composed of approximately 300,000 picture elements, and each picture element is composed of red (R), green (G), and blue (R), so the total number of pixels is 900,000. It is made up of pixels.

These single pixels are arranged in a matrix for each color as shown in FIG. Arranged.

A switching element such as a FET transistor for performing a switching action is provided on the intersection of each matrix electrode, and R, G, H
Each filter is configured to transmit light from the white light source 11.

``Problems to be solved by the invention'' However, in the case of conventional devices, color filters are R, G,
Since each pixel was provided for each B, the structure was precise and complicated, but since 900,000 single pixels were required, it was not suitable for downsizing the device. Furthermore, color display 1o
The characteristics of voltage V and transmittance T are the first in relation to semiconductor characteristics.
As shown in Figure 0, the image reproducibility was not sufficient due to nonlinearity.An object of the present invention is to provide a liquid crystal display device that can display a color image without using a single-color filter. be.

In order to achieve the above object, the present invention provides an optical member having a large number of light shutters arranged in a matrix, each of which opens and closes in a dot shape, and a light emitted from the A light source consisting of a large number of light emitting diodes provided so as to pass through an optical shutter, the optical member being driven by a synchronization signal of an image signal, and the light source being modulated and driven by a luminance signal of the image signal. We propose a liquid crystal display device that

"Operation" The optical member is driven by the synchronization signal separated from the video signal, and the optical shutter is sequentially opened and closed in a predetermined order. Further, the light source is modulated and driven by a luminance signal separated from the video signal, and the light emitted from the light emitting diode passes through the optical shutter and is irradiated.

Therefore, it is possible to obtain a screen with gradation due to the afterimage phenomenon caused by the human eye.

``Example'' An example of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 20 denotes a liquid crystal display as an optical member in which optical shutters are arranged in a matrix, and is constituted by a known dot matrix liquid crystal plate that opens and closes in a dot shape.

A vertical synchronizing signal V and a horizontal synchronizing signal H are supplied to the liquid crystal display 20, and the dot-shaped optical shutters are sequentially opened and closed in a predetermined order.

A backlight 22 is arranged on the back side of the liquid crystal display 20 via a diffusion plate 21, and the backlight 22 has a large number of LEDs (light emitting diodes) arranged.
As shown in FIG. 2, red light emitting diodes 23, green light emitting diodes 24, and blue light emitting diodes 25 are grouped and arranged on a straight line. Each LED is provided with a synchronous separation circuit 26 as shown in FIG.
The luminance signal Y separated from the video signal generator is supplied via the luminance signal amplification circuit 27, and as shown in FIG.
It is designed to be supplied as a signal distributed in the ratio of YR, bYG, and cYB.

That is, the distribution ratio of the luminance signal Y is adjusted by each of the separation circuits 28, 29, and 30. That is, constants a, b,
Color balance can be maintained by adjusting the value of c.

Note that the constants a, b, and c are set in a relationship of a + b + c = 1.

In addition, as shown in Fig. 5, each LED 23.24.2
5 are each connected to the shift register 31, and each LE
When the color signals R1G and B supplied to D23, 24, and 25 are selected by the shift register 31, the LEDs in the selected column emit light.

Further, as shown in FIG. 3, the liquid crystal display 20 is supplied with a horizontal synchronizing signal H from a horizontal synchronizing circuit 32 via an oscillator and a shift register 33, and a vertical synchronizing signal V from a vertical synchronizing circuit 34. is supplied via an oscillator and a shift register 35. In this way, the vertical synchronization signal V
By supplying the horizontal synchronizing signal H, the liquid crystal display 20
The dot-shaped light shutters are sequentially opened and closed.

In the above configuration, when the shift register 31 is operated in accordance with the vertical synchronization signal V, the LEDs in each column are lit in accordance with the luminance signal Y. That is, among the red, green, and blue LEDs, three-color LEDs are sequentially modulated and driven one by one, with one horizontal row serving as one set, and these are displayed on the liquid crystal display 20 as the optical shutter opens and closes. On the other hand, if shift registers 36, 37, and 38 are arranged for each color signal R, G, and B as shown in FIG. , Bn are divided into 1 row R, G1. B row G1, B...
R,, column B,, R,, G2, column R2, G2, B21
1111, it is also possible to drive the g with fine changes.

In the embodiment described above, since the entire surface of the liquid crystal display 20 is scanned, the light utilization rate of the backlight 22 is low and the screen becomes dark. From this, as shown in FIG. 7, if the screen of the liquid crystal display 20 is divided into n parts and each screen is reproduced in the above-described manner, the number of dots of the optical shutter included in each screen can be reduced. The release time can be extended by n times and a brighter image can be obtained. In this case, the electrical drive method is to temporarily store the information for one screen in a memory and take it out from the memory as a signal divided into four parts for each screen/screen, and then take out the information for one screen (1730 seconds to 17 seconds) from the memory.
LCD display 2 as a signal extended to 60 seconds)
0 can be used.

Further, in the above embodiment, the liquid crystal display 20 is used, but the same effect as in the above embodiment can be obtained even if a perovskite-based translucent sintered body (transparent alumina, PLZT) is used. .

Further, according to the above embodiment, since the LED is modulated and driven by the luminance signal, the signal-to-brightness characteristic shown in FIG. 10 can be made into a linear characteristic.

Although specific examples of color images have been described above, monochrome images can be displayed if many LEDs of the backlight 22 are light emitting diodes of the same wavelength, and the power consumption of the light source increases. All the LEDs of the backlight 22 may be turned on according to the brightness signal Y.

"Effects of the Invention" As explained above, according to the present invention, it is possible to display a color image without using a color filter with a complicated structure, which is extremely advantageous in making the device compact, and also Since the brightness has a linear characteristic, the image display device has excellent image reproduction.

[Brief explanation of the drawing]

FIG. 1 is a simplified exploded perspective view of a liquid crystal display device showing an embodiment of the present invention, FIG. 2 is a configuration diagram of main parts of a backlight,
FIG. 3 is a block diagram of a drive circuit of a device according to the present invention, FIG. 4 is a block diagram showing a luminance signal output circuit, FIG. 5 is a block diagram showing an example of backlight modulation drive, and FIG. 6 is a block diagram showing a backlight modulation drive example. Other strange rJR1i! FIG. 7 is a simplified configuration diagram of a liquid crystal display having divided images, FIG. 8 is a simplified exploded perspective view of a conventional liquid crystal display device, and FIG. 9 is an explanation of the configuration of a conventional color filter. 10 are diagrams showing the relationship between applied voltage and transmittance. 20...Liquid crystal display 21...Diffusion plate 22...Backlight 23.24, 25...LED 31.36.37.38...Shift register patent applicant Stanley Electric Co., Ltd. Company representative patent attorney small
Hiroharu Ike "Figure 7 Figure 9 GBRGB Figure 8 fil 10 rlJ Input voltage V

Claims (4)

[Claims] (1) An optical member having a large number of light shutters arranged in a matrix, each of which opens and closes in the form of a dot, and a light source consisting of a large number of light emitting diodes arranged so that the emitted light passes through the light shutters. . A liquid crystal display device, wherein the optical member is driven by a synchronization signal of an image signal, and the light source is modulated and driven by a luminance signal of the image signal. (2) The liquid crystal display device according to claim (1), wherein the light source is constructed using light emitting diodes having different emission wavelengths. (3) The liquid crystal display device according to claim (1), wherein the light emitting diode of the light source is selectively modulated and driven with respect to the optical member driven in accordance with a synchronizing signal. (4) A liquid crystal display device according to claim (1), wherein the optical member and the light source are driven by a synchronization signal of an image signal, and the light source is modulated by a luminance signal of the image signal.