JPH04116893U - liquid crystal display device - Google Patents

Abstract

(57) [Summary] [Purpose] The contrast does not change significantly depending on the viewing direction. [Configuration] The contrast adjustment circuit 4 of the liquid crystal display 1 is
A switching circuit 9 is provided that switches the voltage applied to the electrodes of the liquid crystal display by the drive circuit 2 at a predetermined period. If the voltage applied to the electrodes of a liquid crystal display is switched at a predetermined period, the contrast will not change significantly depending on the viewing direction.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to controlling the contrast of a liquid crystal display device.

0002

[Conventional technology]

FIG. 2 is a block diagram schematically showing the structure of a conventional liquid crystal display device. As shown in the figure, the conventional device includes a liquid crystal panel section 13 including a liquid crystal display (LCD) 11 and a drive circuit 12 thereof, and a drive circuit 12 that applies voltage to electrodes (not shown) of the LCD 11. It has a contrast adjustment circuit 14 that sets the voltage. The contrast adjustment circuit 4 divides the voltage (V _DD −V _SS ) using a variable resistor _RV and supplies the divided voltage V _LCD to the drive circuit 12 . The drive circuit 12 applies a voltage V _LCD to the electrodes of the LCD 11 .

0003 Figure 3 is an explanatory diagram showing the principle of contrast adjustment in a conventional liquid crystal display device. be. As shown in the figure, in the conventional liquid crystal display device, the electrodes of the LCD 11 are By changing the voltage applied to the The contrast is adjusted by taking advantage of the movement of the direction of the . For example, as shown in FIG. 3, the position of the eye observing the LCD 11 is E, When the direction in which the LCD 11 is observed is the F direction, the viewing direction is adjusted to increase the contrast. Move the direction of the viewing angle closer to the LCD observation direction F (A in the diagram) and lower the contrast. To do this, move the viewing angle away from the LCD observation direction F (B in the figure).

0004

[Problem that the idea aims to solve]

However, from another perspective, the contrast adjustment of the LCD It can also be said that this is an adjustment method that takes advantage of the fact that the viewing angle itself is narrow. Therefore, the observation If the eye position E changes and the viewing direction F changes, the contrast will also change. There was a problem that the screen was difficult to see.

[0005] Therefore, this invention was devised to solve the above problems, and its purpose is to However, we provide a liquid crystal display device whose contrast does not change significantly depending on the viewing direction. It's about doing.

[0006]

[Means to solve the problem]

In the present invention, a liquid crystal display device comprising a liquid crystal layer and electrodes that apply voltage to the liquid crystal layer is used. , a driving circuit that applies voltage to the electrodes of the liquid crystal display to display an image on the liquid crystal layer; and a controller for setting the voltage applied to the electrodes of the liquid crystal display by the drive circuit. In a liquid crystal display device having a contrast adjustment circuit, the contrast adjustment circuit a voltage applied to the electrodes of the liquid crystal display by the drive circuit at a predetermined period; It is characterized by having a circuit that switches between.

[0007]

[Effect]

In the present invention, the contrast adjustment circuit applies voltage to the electrodes of the liquid crystal display. Two types of this voltage are set depending on the set contrast, and the voltage is set at a predetermined period. Switch. By switching the voltage at predetermined intervals in this way, the apparent viewing angle can be changed. This can alleviate the tendency for the contrast to change greatly depending on the viewing direction. Ru.

[0008]

【Example】

FIG. 1 is a block diagram showing the configuration of an embodiment of a liquid crystal display device according to the present invention. . As shown in the figure, the device of this embodiment includes a liquid crystal display (LCD) 1 and its A liquid crystal panel section 3 including a drive circuit 2, a contrast adjustment circuit 4, and a controller. 5.

[0009] The LCD 1 includes a common electrode (not shown) and a plurality of pixel electrodes (not shown) facing the common electrode. (not shown) and a liquid crystal layer (not shown) sandwiched between the two electrodes.

0010 The drive circuit 2 applies a voltage between the common electrode and the pixel electrode of the LCD 1 to drive the liquid crystal. Display images by changing orientation characteristics.

The contrast adjustment circuit 4 adjusts the voltage (V _DD −V _SS ) between the variable resistor R _V and the resistor R ₁ (synthesized resistance value (R _V +R ₁ )), or between the variable resistor R _V and the resistor R ₂ The voltage is divided by (combined resistance value (R _V +R ₂ )), and this divided voltage V _LCD is applied to the drive circuit 2 . The contrast adjustment circuit 4 has a switching circuit 9 consisting of an F/F (flip-flop) circuit 6 and transistors 7 and 8 that use the F/F circuit output as a gate signal, and determines the voltage _VLCD . The voltage dividing resistor is switched to (R _V +R ₁ ) or (R _V +R ₂ ) in synchronization with the liquid crystal alternating current signal c.

0012 The controller 5 supplies liquid to the drive circuit 2 and the contrast adjustment circuit 4 at a constant cycle. In addition to supplying the crystal alternating signal c, the drive circuit 2 is supplied with a control signal including image display data. supply.

FIG. 4 is a waveform diagram for explaining the operation of the liquid crystal display device of this embodiment. The F/F circuit 6 outputs, as outputs a and b, signals of opposite polarity that turn on and off in synchronization with the liquid crystal alternating current signal c. Transistors 7 and 8 are turned on and off in synchronization with the on and off of outputs a and b of F/F circuit 6. Therefore, the voltage _VLCD input to the drive circuit 2 is also switched in synchronization with the output of the F/F circuit 6.

FIG. 5 is an explanatory diagram showing the principle of contrast adjustment in this embodiment. As shown in the figure, the contrast adjustment in the liquid crystal display device of this embodiment is basically performed by changing the resistance value of the variable resistor R _V of the contrast adjustment circuit 4, similarly to the conventional example shown in FIG. This is done by changing the direction of the viewing angle.

[0015] However, in this example, simply changing the direction of the viewing angle according to the contrast is sufficient. Instead, the viewing angle is oscillated by a constant width. For example, as shown in FIG. When the position of the eye observing D1 is E and the direction of observing LCD1 is arrow F. In order to increase the contrast, the direction of the viewing angle should be swung between C and C' to lower it. In this case, the direction of the viewing angle is oscillated between D and D'.

[0016] Therefore, in this embodiment, the contrast adjustment circuit 4 Two types of voltages are set depending on the set contrast, and the voltage applied to the Switch the voltage in the period.

[0017] Therefore, if the voltage is switched at a predetermined period in this way, the direction of the viewing angle will be as shown in Figure 5. The deflection to C and C' (or the deflection to D and D') increases the apparent viewing angle, making it easier to see. This can alleviate the drawback that the contrast changes greatly depending on the orientation.

[0018]

[Effect of the idea]

In the present invention, the contrast adjustment circuit includes a voltage applied to the electrodes of the LCD. Two types are set according to the set contrast, and the voltage is switched at a predetermined cycle. Well, if you increase the apparent viewing angle and the contrast changes greatly depending on the viewing direction. This alleviates the drawbacks.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a configuration diagram schematically showing the configuration of a conventional liquid crystal display device.

FIG. 3 is an explanatory diagram showing the principle of contrast adjustment in a conventional liquid crystal display device.

FIG. 4 is a waveform chart for explaining the operation of the liquid crystal display device of this embodiment.

FIG. 5 is an explanatory diagram showing the principle of contrast adjustment in this embodiment.

[Explanation of symbols]

1 Liquid crystal display (LCD) 2 Drive circuit 3 LCD panel section 4 Contrast adjustment circuit 5 Controller 9 Switching circuit

Claims (1)

[Scope of utility model registration request] 1. A liquid crystal display comprising a liquid crystal layer and an electrode for applying a voltage to the liquid crystal layer, a drive circuit for applying a voltage to the electrodes of the liquid crystal display to display an image on the liquid crystal layer, and the drive circuit. and a contrast adjustment circuit that sets the voltage applied to the electrodes of the liquid crystal display by the drive circuit, wherein the contrast adjustment circuit adjusts the voltage applied to the electrodes of the liquid crystal display by the drive circuit to a predetermined value. A liquid crystal display device characterized by being equipped with a circuit that switches periodically.