JPS58196587A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display device which includes a converter and a 5A-D converter to convert an A/C signal into a digital F7 signal, and which displays all halftones in multiple LX levels.

After converting the anacogonic image signal into the entire digital image signal, the liquid crystal drive waveform's small movement time ratio between the selected and non-selected forms is controlled by the digital video signal, and the liquid crystal In order to display a liquid crystal panel, AC voltage driving is desirable from the viewpoint of longevity. When the liquid crystal panel is multiflex driven, a selection voltage waveform is applied to each pixel of the liquid crystal panel in a selected state, and a non-selection voltage waveform in a non-selected state.

In general, the non-select voltage waveform during multi-flex driving of the liquid crystal panel, the effective value is not zero, and the ratio of the effective values of the selected voltage waveform and the non-selected voltage waveform is Since it is finite, as the number of common electric maple divisions increases, only a small display of the Fun r last ratio can be obtained.

Even if the contrast ratio between the brightest display state and the darkest display state is small, even if the entire image is displayed on a dull liquid crystal panel with a contrast corresponding to the analog narrow image signal information, 1. Clear image display is not possible.

The purpose of the invention is also to reduce the contrast ratio of liquid crystal panels.1. Clear images can be achieved by providing a liquid crystal display device that can display images. The first example is a block diagram showing an example of a liquid crystal panel driving section included in a conventional liquid crystal display device.

The liquid crystal panel 1 drive section includes a controller 11, an A-D converter i2, a common electrode drive circuit 16, a signal electrode drive circuit 14, a drive waveform generation circuit 15, a liquid crystal panel 16, and an imaging circuit 17.

The analog video signal Av is sent to the -A-D converter 12.
The controller 11 receives the synchronization signal and converts the digital video signal Dvf into the common electrode drive circuit 1.
6 and the signal electrode drive circuit 14 with control signals C and A.
and C8 are output. Digital video 'tI signal D'l'j outputted from the D converter 12:, control signal 8t/? :, L, one common electrode of the liquid crystal panel 16 is connected to the signal electrode drive circuit 14. The common electrode drive circuit 13 selects the function of the liquid crystal panel 16 each time the brush selects the function of the liquid crystal panel 16, and selects the two stored images accordingly. Waveform and non-′
When driving with the Fusawa waveform; 'Frl converted signal layer'
[The auxiliary waveform is output from the output terminal of the 1-word rotational rotation 14, and! Power is applied to 16 night crystal panels.

In this way, while the signal electrode drive circuit 14 is outputting the signal electrode drive waveform corresponding to the stored digital video signal Dv, the signal electrode drive circuit 14 outputs the digital video signal Dv for the next common electrode. accept the human power of The common electrode drive circuit 16 (memory) receives a control signal Ccf from the controller 11 and sequentially switches and outputs the selected common electrode drive waveforms applied to the common electrodes of the liquid crystal panel 16 to the common electrodes of the liquid crystal panel 16.

By repeating the above operations, a multi-tone image can be displayed on the liquid crystal panel 16.

The drive waveform generation circuit 15 is a circuit that generates selection waveforms and non-selection waveforms for the signal electrodes, and 4-choice waveforms and non-selection waveforms for the common electrode of the liquid crystal panel 16, and their outputs are as follows: γL is applied to the signal electrode drive circuit 14 and the common electrode drive circuit 13.

toyX oscillation circuit 17 drives these systems.
It is used to generate a clock signal for In this way, when displaying multiple tones on a liquid crystal panel, even if the gradation is actually done in 16 or more gradations, the difference between adjacent gradations is noticeable to the human eye. I can't feel it. When a liquid crystal panel is multi-lux driven using AC drive, a large contrast ratio cannot be obtained because the driving voltage margin between the selected state and the non-selected state cannot be set large.

For this reason, for example, when displaying a television picture 1tJk, if the video signal sent from the broadcasting station is faithfully converted into a gradation that can be displayed on the liquid crystal panel and displayed, the image will be reproduced as a lack of sharpness. Visually, if the texture of the subject deteriorates, or if the subject and background have close gradation differences, the outline of the subject will be perceived as blurred.

FIG. 2 is a block diagram of a liquid crystal display device showing one embodiment of the present invention.

In FIG. 21, 21 is a liquid crystal panel drive section having an A'-D converter 22 that converts an analog video signal into a digital video signal. A circuit 20 for listening to the frequency characteristics in the upward direction to the right is inserted at the front stage of this A-D converter. A circuit having an upward-sloping frequency characteristic means that the output signal voltage, output signal current, or output signal power varies with the frequency f of the input signal, as shown in FIG. 3a or b.
is defined as a circuit with characteristics that increase as .

As shown in a, the output signal voltage, output signal current, or output signal power may show a linear increase with respect to an increase in the frequency of the human signal, or as shown in b However, it is not necessary to maintain the upward-sloping frequency characteristic up to the upper limit of the frequency band of the analog video signal.

Some 20 pieces have the upward-sloping frequency characteristics explained above.
As a result, the analog video signal Av from the outside has high frequency components, and then is warmed by the A-D converter 22 and becomes a digital video signal.

As shown in Figure 4a, the change in the analog video signal is A
Even if the change does not exceed the comparator level Cn f of the -D converter, the output of the A-D converter does not change, so the image tends to become unclear and blurred.

In the liquid crystal display device shown in Figure 2, the analog video signal is passed through a circuit that listens to the upward-sloping frequency characteristic, emphasizing high frequency components. The frequency component analog video signal is selectively A-
It becomes easy to change beyond the comparator level of the D converter, and it is easy to give an output change to the A'-D converter.

The high-frequency components of the analog video signal that exceed the comparator level of the A-D converter are further displayed on the liquid crystal spring as a large gradation change, making it possible to realize a clear liquid crystal display image. . Since the circuit 2aI-i has a frequency characteristic that rises to the right, the low frequency components of the analog video signal are not emphasized, and therefore the displayed image can vary from an overall bright image to an overall dark image. The overall brightness information of the input analog video signal can be reproduced on the LCD panel with greater fidelity.

FIG. 5 shows a specific array of circuits 20 having the same frequency characteristics as shown in FIG. show. The circuit shown in FIG. 5a is a circuit in which a parallel vC1 capacitor 52 is connected to a base resistor 51 of a well-circumscribed emitter 7 lower.

Circuit fd in Figure 5 shows a resistor 54 and a capacitor 55 in parallel with the eminome resistor] 3 of a general transistor amplifier circuit.
By connecting the series circuit of

FIG. 5 is only a circuit showing two specific examples of the circuit 20 in FIG. Good too. In addition, in FIG. 2, times ##r2 CJ fcA-D
Although it was placed just before the converter 22, due to the invention, 1
, an analog video signal is transmitted by an A-D converter, and it may be provided anywhere between the systems.

According to the above-mentioned blinds, the overall brightness of the displayed image is such that human-powered analog video signals can be reproduced almost faithfully on the liquid crystal panel, and a clear image on one side of the liquid crystal display can be produced. It becomes possible to provide a liquid crystal display device that can be reproduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an entire row of liquid crystal/channel driving parts in a conventional liquid crystal display device.
A block diagram of a liquid crystal display device showing an embodiment of the invention; Fig. 6 is a graph showing a specific example of frequency customization in upper right corner 9; 41Aa, b, analog video signal manually input to the A-D converter; Graph showing Figure 5 a', big,
FIG. 2 is a circuit diagram illustrating two specific examples of a circuit having an upward-sloping frequency characteristic. 1222...A-D converter 20...Circuit having stone-climbed frequency characteristics 51.53.
．． 54...Resistance 52.55--Capacitor or more Applicant Daini Seikodai Co., Ltd. Agent Patent attorney Mogami

Claims (1)

[Claims] The liquid crystal display device that connects the A-D converter to the analog video signal tte 1 digital signal 1 in the summer, and the A-D converter EF is also in the front stage, and has a frequency characteristic that rises to the right. A liquid crystal display device characterized by being equipped with a shoulder circuit.