JPS63235995A - Matrix type liquid crystal display device - 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] [Summary] The present invention is an active matrix type liquid crystal display device that performs halftone display and binary display in the same device. By including and widening the actual applied voltage range, it is possible to fully bring out the contrast and viewing angle of the liquid crystal.

[Industrial application field]

The present invention relates to an active matrix liquid crystal display device, and particularly to a liquid crystal display device that performs halftone display and binary display in the same device.

[Conventional technology]

Liquid crystal display devices have come to be widely used as display devices for TVs and computer terminals. Conventionally, this LCD TV and a binary display liquid crystal display device are separate devices.
There is no single device that displays both. However, in the future, similar to CRTs, there is a trend that a single device will be required to perform both halftone display and binary display.

Therefore, here, a description will be given of halftone display on a liquid crystal TV.

The transmitted light intensity characteristics of the liquid crystal draw an S-shaped curve with respect to the applied voltage, as shown in FIG. To display halftones,
It is necessary to avoid the saturated region and use the sloped part of the curve. Therefore, the range of voltage applied to the liquid crystal is from 7 to V ma.

You can set it up until then.

Setting range ΔV (v, aX and V m i
If the difference (difference from n) is set too wide and, for example, V mix enters the saturated region, halftone collapse will occur at the white level. Therefore, when performing halftone display, it is important to appropriately set the range of applied voltage.

On the other hand, in the case of binary display, in order to strengthen the contrast,
It is preferable to use the saturated region rather than the sloped portion of the curve.

[Problem that the invention seeks to solve]

As described above, there is a problem in that the optimum range of the voltage applied to the liquid crystal is different between halftone display and binary display.

An object of the present invention is to enable a single device to perform both halftone display and binary display under optimal conditions.

[Means for solving problems]

FIG. 1 shows the applied voltage range of the liquid crystal display device of the present invention.

The applied voltage range for binary display is expanded to both sides of the applied voltage range for halftone display. The high level of the binary display is ■
°□-, low level is level ' m r n, high level VIII low level V during halftone display
For m r□, V' may > V max + V' mi
. <I set it to V, 1.

[For production]

When displaying halftones, the sloped part of the transmittance characteristic is used,
Since the saturated area is used for binary display, there is no halftone distortion in halftone display, and in binary display, it is possible to use parts of the liquid crystal with stable characteristics, so clear contrast can be obtained. Can be done.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 2 shows the main structure of the above embodiment.

As seen in the figure, there are two input systems: a TV signal and an external RGB signal.The TV signal is separated into three RGB signals by an RGB decoder 3, and then enters an RGB interface circuit 4.

Before the external RGB signal enters the RGB interface circuit 4, it is amplified by the amplifier 2 and set to a voltage range wider than the voltage range of each RGB signal separated from the TV signal.

TV signals and external RGB signals are connected to RGB interface 4.
After being amplified by the amplifier 5 to the voltage to be applied to the liquid crystal panel, the liquid crystal drive driver (not shown)
is input.

Here, the maximum value V m of the applied voltage corresponding to the TV signal
a X and the minimum value V0. As shown in FIG. 1, it is necessary to select the amplification degree of the amplifier 5 so that it falls within the slope of the transmittance characteristic of the liquid crystal.

By selecting the amplification degree of the amplifier 5 as described above, the input voltage to the amplifier 5 has a larger maximum value and a smaller minimum value in the case of an external RGB signal than in the case of a TV signal. As explained in Figure 1, the external RG
The voltage range applied to the liquid crystal panel in the case of B signal is T
It is wide and includes the applied voltage range in case of V signal.

FIG. 3 (al, (bl) shows the voltage waveforms applied to the liquid crystal panel that are input to the liquid crystal driver for the case of a TV signal and the case of a binary display signal.

As described above, according to this embodiment, since the applied voltage range is set to use the slope part of the transmittance characteristic of the liquid crystal for the multi-gradation signal, halftones can be displayed, and the binary signal is stable. Since a saturated area is used, black and white can be displayed with good contrast.

In the above embodiment, the amplifier 2 constitutes the applied voltage range setting means, but the means or method for setting the applied voltage range is not particularly limited to this and may be selected from various methods.

〔Effect of the invention〕

According to the present invention, in order to widen the voltage setting of the binary display while keeping the halftone display within an appropriate voltage setting range, it is possible to use an area in which the liquid crystal is stable in the binary display, and to achieve high contrast. Provides a wide viewing angle.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a diagram illustrating an embodiment of the present invention, FIG. 3 is a diagram illustrating voltage waveforms applied to a liquid crystal panel, and FIG. 4 is a diagram illustrating a liquid crystal TV voltage setting range. In the figure, 1 is a voltage setting means, 2 is an amplifier, and 3 is an RG
B decoder, 4 is RGB interface, ETJ7JD
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Claims (1)

[Claims] In a liquid crystal display device that performs halftone display or binary display by applying a voltage corresponding to the voltage of an inputted multi-gradation signal or binary signal to a liquid crystal panel, When generating the applied voltage to the liquid crystal display panel, the applied voltage range (ΔV') corresponding to the voltage width of the binary signal is set to include the applied voltage range (ΔV) corresponding to the voltage width of the multi-gradation signal, and A matrix type liquid crystal display device characterized by being wider than that.