JP2001174778A - Color liquid crystal display apparatus and driving method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To turn a liquid crystal display apparatus into a color display without increasing the driving circuit in size. SOLUTION: In a color liquid crystal display apparatus provided with a circuit for driving a liquid crystal on a silicon wafer, each pixel is provided with six pieces of capacitors to decide the impression voltage to the display pixel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color liquid crystal display device and a driving method thereof.

[0002]

2. Description of the Related Art There is a field sequential driving method as a method for displaying a monochrome liquid crystal display device in color. A display corresponding to red (R) is displayed on a monochrome screen, and red light is simultaneously emitted to obtain an R display. Next, a display corresponding to green (G) is displayed, and green light is emitted.
Get the display. Further, a display corresponding to blue (B) is emitted and blue light is emitted to obtain a B display. In this manner, the color display is sequentially repeated by setting three fields of each color as one frame. Irradiation of light may be of a backlight type or a front light type, and may be of a transmission type or a reflection type.

The advantages of the field-sequential system by comparing the color filter system used in a general color liquid crystal display device with the field-sequential system are as follows: 1) No expensive color filter is required to obtain a color display. . 2) Since it is a monochrome screen, the transmittance (reflectance) is high and the light efficiency is good. 3) Since the light from the backlight (front light) is directly output, an image with good color purity can be obtained. 4) Since it is a monochrome screen, the number of pixels is reduced to 1/3. If the screen is the same, three times the number of pixels can be obtained.

FIG. 1 is a circuit diagram for explaining driving of a monochrome liquid crystal display device. The driving of the liquid crystal is to apply a driving voltage to the liquid crystal interposed between the display electrode and the common electrode by turning on and off the display electrode, and the gradation of the display is changed according to the time for applying the driving voltage. Reference numeral 1 denotes a video signal input terminal, and a video signal is supplied to the switch 3 every one field period.
And written into the capacitor (C1) 5 and the capacitor (C2) 6. One terminal of the capacitor is connected to the ground G. 2 is a reference voltage supply terminal,
It is connected to the comparator 7. The voltage written to the capacitor 5 or 6 is switched by the switch 4. The read voltage is input to the comparator 7. The comparator 7 compares the reference voltage with the read voltage and outputs an ON or OFF signal. Reference numeral 8 denotes a display electrode which is turned on / off by an output signal of the comparator 7.

FIG. 2 is a waveform diagram for explaining the driving circuit of FIG. (1) is 1V during one field period. The reference voltage supply terminal 2 is supplied with the ramp signal Vramp twice during one field period. The read voltage from the capacitor 5 is assumed to be Va. The comparator 7 has a reference voltage V
The ramp is compared with the read voltage Va. When the reference voltage Vramp is lower than the read voltage Va (period (4)), the display electrode 8 is turned on.
Output an ON signal to the reference voltage V from the read voltage Va.
When the ramp is high (period (5)), an off signal is output to the display electrode 8. The light source of the irradiating light is turned on only for フ ィ ー ル ド field (period (2)), and actually used for display is the period (4) where the reference voltage Vramp is lower than the read voltage Va. That is, the luminance level is determined by the voltage Va.
In the period (3), the light source is in the OFF state, and during this period, the voltage applied to the liquid crystal layer is inverted and the liquid crystal layer is driven by AC.

The field sequential system for displaying a monochrome screen liquid crystal display device in color is a system in which three fields of each color are successively repeated with one frame as one frame, so that one field period is １ ／ of that of monochrome display. It will be. FIG. 3 is a block diagram of the field sequential system. Reference numeral 9 denotes a video signal input terminal, and the video signal is input to the decoder 10. The video signal is separated into three-color signals of G, B, and R by a decoder 10, converted into digital signals by A / D converters 11, 12, and 13, respectively, and stored in FIFO memories 14, 15, 15 ', and 16, respectively. . The signal read by the sequential method is output from the output terminal 17, is converted into an analog signal by a D / A converter (not shown), and is input to the video input terminal 1 shown in FIG. A display corresponding to green (G) is displayed on the monochrome screen, and simultaneously, green light is emitted to obtain a G display. Next, a display corresponding to blue (B) is emitted and blue light is irradiated to obtain a B display. Further, a display corresponding to red (R) is emitted and red light is irradiated to obtain an R display. The display period of each color is 1/3 of the monochrome display period.

[0007]

The drawbacks of the field sequential system are as follows: 1) Light sources of three different colors are required, and these sequential drives are required. 2) Since one ordinary frame is separated into R, G, and B signals of three colors in parallel, it is necessary to convert the signals into sequential signals of each color, and the video signal conversion circuit has a large number of parts and a large circuit scale. The substrate area increases and the cost also increases. An object of the present invention is to eliminate the need for a video signal conversion circuit without changing the pixels and resolution of a reflection type liquid crystal display device having a liquid crystal driving circuit on a silicon wafer, but it is necessary to use light sources of three different colors. Sex does not change.

[0008]

SUMMARY OF THE INVENTION In a color liquid crystal display device having a liquid crystal driving circuit provided on a silicon wafer, a capacitor (local capacitance) for determining a voltage applied to a display pixel.
Is a color liquid crystal display device provided with six per pixel.

An input video signal is converted by a decoder into R, G,
The primary color signal is converted to a primary color signal, and the converted signal is applied to six display capacitors provided inside the back plane of the liquid crystal display device at a voltage value corresponding to the luminance level, and synchronized with the clock of the number of pixels. Write, switch to R,
The driving method is a method of driving a color liquid crystal display device in which the display is converted into the G and B sequential methods and the display voltage of one pixel is determined.

[0010]

FIG. 4 is a circuit diagram for explaining the driving of the liquid crystal display device of the present invention. FIG. 5 is a waveform diagram for explaining the drive circuit of FIG. The video signals G, B, and R separated by the decoder are input terminals G,
B and R are input. The video signal G is switched by the switch 21 every field period and the capacitor (C1
1) 51, written in the capacitor (C21) 61. The video signal B is switched by the switch 22 every field period and written into the capacitor (C12) 52 and the capacitor (C22) 62. The video signal R is switched by the switch 23 every field period and written into the capacitor (C13) 53 and the capacitor (C23) 63. One terminal of each capacitor is connected to the ground G.

Reference numeral 19 denotes a reference voltage supply terminal, which is connected to the comparator 20. The voltage written to the capacitor 51 or 61 is switched by the switch 24 and read. The voltage written to the capacitor 52 or 62 is switched by the switch 25 and read. The voltage written to the capacitor 53 or 63 is switched by the switch 26 and read. The voltage written in the capacitor is switched by the switch 18 and input to the comparator 20. The comparator 20 compares the reference voltage 19 with the read voltage and outputs an ON or OFF signal. Reference numeral 8 denotes a display electrode which is turned on / off by an output signal of the comparator 20.

In FIG. 5, (1) is a period 1V of one field, which is the same as the period 1V of one field in the monochrome display shown in FIG. The light source, which is illumination, divides 1V into 6 parts, GON, GOFF, BON, BOFF, RO
The lights are turned on and off in the order of N and ROFF. The voltage of the video signal G is Vg, the voltage of the video signal B is Vb, and the video signal R
Is the voltage Vr, and the display electrode 8 is turned on during the periods (6), (8) and (10) and turned off during the periods (7), (9) and (11). Green is displayed for the period of (6), blue is displayed for the period of (8),
During the period of (10), the display is red, and the colors are synthesized by the human eyes and regarded as a color display.

The present invention simplifies the color driving circuit of the liquid crystal display device by providing six capacitors for determining the applied voltage of the display pixel per pixel. However, it is necessary to provide six capacitors for one pixel. There is a feature. Depending on the size of the display electrode, it may be difficult to provide six storage capacitors under the display electrode of one pixel. In order to increase the resolution, in the present invention, it is desirable to employ a trench type memory cell structure which can reduce the planar area of the storage capacitor as compared with the stacked type memory cell as the structure of the back plane.

[0014]

Since the video signal can be converted in the liquid crystal drive circuit on the silicon wafer, there is no need to provide a new video signal conversion circuit, and a small and inexpensive color liquid crystal display device can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram for explaining driving of a monochrome liquid crystal display device.

FIG. 2 is a waveform chart for explaining the drive circuit of FIG. 1;

FIG. 3 is a block diagram of a field sequential system.

FIG. 4 is a circuit diagram for explaining driving of the liquid crystal display device of the present invention.

FIG. 5 is a waveform chart for explaining the drive circuit of FIG. 4;

[Explanation of symbols]

 Reference Signs List 1 Video signal input terminal 2 Reference voltage supply terminal 3 Switch 4 Switch 5 Capacitor 6 Capacitor 7 Comparator 8 Display electrode 9 Video signal input terminal 10 Decoder 11 A / D converter 12 A / D converter 13 A / D converter 14 FIFO Memory 15 FIFO memory 15 'FIFO memory 16 FIFO memory 17 Output terminal 18 Switch 19 Reference voltage 20 Comparator 21 Switch 22 Switch 23 Switch 24 Switch 25 Switch 26 Switch 51 Capacitor 52 Capacitor 52 Capacitor 61 Capacitor 62 Capacitor 63 Capacitor G Ground

Continued on front page F-term (reference) 2H093 NA65 NC14 NC15 NC16 NC21 NC43 NC44 ND17 ND49 ND54 NE01 5C006 AA01 AA15 AC28 AF44 AF85 BB15 BB29 BC20 BF11 BF14 BF24 BF26 BF37 FA41 FA56 5C080 AA10 BB05 JJ05 JJ30 EE02

Claims (2)

[Claims] 1. A color liquid crystal display device provided with a liquid crystal drive circuit on a silicon wafer, comprising six capacitors per pixel for determining a voltage applied to a display pixel. 2. An input video signal is converted to R,
G and B primary color signals are converted into primary color signals, and the converted signals are applied to six display capacitors provided inside the back plane of the liquid crystal display device at a voltage value corresponding to the luminance level to generate a clock for the number of pixels. A method for driving a color liquid crystal display device, comprising: writing in synchronism, converting to an R, G, B sequential method by a switch, and determining a display voltage of one pixel.