JPH10301094A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of the display irregularity of the picture caused by the temperature distribution generated by the heat of the light source of the back light unit of a liquid crystal display device. SOLUTION: The back light unit having a fluorescent lamp 5 and a light transmission plate is arranged in the back surface side of a liquid crystal display panel 1. Along the top and the bottom edges of the panel 1, plural driver ICs 2 are arranged to supply signal voltages to each electrode. Moreover, along the other edge of the panel 1, plural driver ICs 3 are arranged to supply scanning voltages to each electrode. Temperature sensing elements 6 and 7 are also arranged in the circumference of the panel 1. A voltage compensating circuit 9 individually adjusts the scanning voltages, which are supplied to each electrode, through the ICs 3 based on the temperature distribution in the panel 1 detected by the elements 6 and 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly to an improvement for preventing the occurrence of image display unevenness in a liquid crystal display panel.

[0002]

2. Description of the Related Art A liquid crystal display device comprises a liquid crystal display panel, a driver IC for driving liquid crystal, a driver control circuit for operating the driver IC, a backlight unit, and a bezel for accommodating these components. The backlight unit includes a light guide plate arranged on the back side of the liquid crystal display panel, a fluorescent lamp arranged along one side of the light guide plate and beside the light guide plate.

[0003] The liquid crystal has a temperature dependency, and the heat is generated by a fluorescent lamp constituting a backlight unit.
When a temperature difference of 5 ° C. or more occurs in the image display area of the liquid crystal display panel, the fluctuation range of the threshold voltage (Vth) of the liquid crystal becomes large, and display unevenness occurs in an image. Therefore, in the conventional liquid crystal display device, the fluorescent lamp, which is a main heat source, is designed to be as far as possible from the image display area.

However, as the frame of the liquid crystal display panel has been narrowed due to restrictions on the external dimensions of the liquid crystal display device, the distance between the fluorescent lamp for the backlight unit and the image display area has to be reduced. As a result, a temperature difference between a portion near the fluorescent lamp and a portion far from the fluorescent lamp in the image display region has become remarkable. As the temperature difference in the image display area increases, Vth of only the portion close to the fluorescent lamp decreases due to the temperature rise, and display unevenness displayed in white has become noticeable.

In order to cope with such a problem, a structure for shutting off the heat input from the fluorescent lamp or a structure for actively releasing the heat of the fluorescent lamp to the outside has been adopted. Not yet.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional liquid crystal display device.
An object of the present invention is to provide a liquid crystal display device of a transmission type that can prevent display unevenness of an image due to a temperature distribution generated by heat generation of a light source of a backlight unit.

[0007]

A liquid crystal display device according to the present invention comprises a liquid crystal display panel having a substrate on which electrodes are formed facing each other, and a light source and a light guide plate disposed on the back side of the liquid crystal display panel. A backlight unit and a plurality of driver ICs arranged along one side of the liquid crystal display panel or two sides facing each other and supplying a signal voltage to each electrode
And a plurality of driver ICs arranged along one other side of the liquid crystal display panel or the other two sides facing each other and supplying a scanning voltage to each electrode. It is characterized by comprising voltage correction means for detecting a surrounding temperature distribution and individually adjusting a scanning voltage supplied to each electrode via each driver IC based on the detected temperature distribution.

(Operation) According to the liquid crystal display device of the present invention,
By detecting the temperature distribution around the liquid crystal display panel and individually adjusting the scanning voltage supplied to each electrode via each driver IC according to the detected temperature distribution, the heat generation of the light source of the backlight unit is achieved. Thereby, the fluctuation of the threshold voltage (Vth) caused by the temperature distribution generated in the liquid crystal display panel is compensated. This suppresses the occurrence of image display unevenness based on the above-described temperature distribution, and realizes uniform image display over the entire image display area.

[0009]

FIG. 1 shows an example of a liquid crystal display device according to the present invention. In the drawing, 1 is a liquid crystal display panel, 2 and 3 are driver ICs, 4 is a driver control circuit, 5 is a fluorescent lamp (light source) of a backlight unit, 6 and 7 are temperature sensing elements, 8 is a temperature comparison circuit, 9 is It represents a voltage correction circuit (voltage correction means). The liquid crystal display panel 1 is a simple matrix type in which substrates on which electrodes are formed face each other.

A plurality of driver ICs 2 for supplying a signal voltage to each pixel are arranged along two sides (in this example, an upper side and a lower side) of the liquid crystal display panel 1 facing each other. A plurality of driver ICs 3 that supply a scanning voltage to each pixel are arranged along another side (the left side in this example) of the liquid crystal display panel 1. A drive signal is supplied from the driver control circuit 4 to the driver IC 2 and the driver IC 3.

On the back side of the liquid crystal display panel 1, a backlight unit is arranged. The backlight unit includes a light guide plate (not shown) arranged on the back surface of the liquid crystal display panel 1, a fluorescent lamp 5 arranged along one side of the light guide plate, and the like. In this example, the fluorescent lamp 5 is disposed on the back side of the driver IC 2 along the upper side of the liquid crystal display panel 1.

At a plurality of locations around the liquid crystal panel 1, temperature sensing elements, such as a thermistor, for detecting a temperature distribution state of the liquid crystal panel 1 are arranged. In this example, a temperature sensing element 6 is arranged on the upper side of the liquid crystal display panel 1 adjacent to the fluorescent lamp 5, and a temperature sensing element 7 is arranged on the lower side of the liquid crystal panel 1 on the opposite side.

The temperature of each part of the liquid crystal display panel 1 is detected by the temperature-sensitive elements 6 and 7, and a predetermined voltage is generated from the temperature-sensitive elements 6 and 7. The two voltages are input to a temperature comparing circuit 8 and compared, and based on the result, a temperature difference is corrected from a voltage correcting circuit 9 to a driver IC 3 that drives an electrode disposed near the fluorescent lamp 5. Is supplied.

FIG. 2 is a diagram showing the waveform of the voltage applied to the electrodes of the liquid crystal display panel 1. The solid line 11 shows the waveform of the scanning voltage, and the broken line 12 shows the waveform of the signal voltage. As can be seen from the figure, the scanning voltage and the signal voltage are inverted every frame, for example. When the scanning voltage is selected at the voltage V5 and unselected at the voltage V1 in n frames,
In the next frame, the selected state is set at the voltage V0 and the non-selected state is set at the voltage V4. Further, as the signal voltage, one of the voltage VO and the voltage V2 is selected according to ON and OFF in the n frame, and one of the voltage V3 and the voltage V5 is selected according to ON and OFF in the next frame. In the figure, a dotted line 13 indicates a voltage applied to an electrode arranged near the fluorescent lamp 5 when a scanning voltage is selected, and functions of the temperature-sensitive elements 6 and 7, the temperature comparison circuit 8 and the voltage correction circuit 9. Is different from the normal case. As a result, in this example, it was possible to suppress the unevenness of the screen conventionally caused by the heat of the lamp 5.

[0015]

According to the liquid crystal display device of the present invention, the temperature distribution generated in the liquid crystal display panel due to the heat generated by the light source of the backlight unit is measured, and the backlight is scanned by using a scanning voltage corresponding to the temperature distribution. Can be driven at a position close to the light source. As a result, the occurrence of image display unevenness due to the temperature distribution is suppressed, and uniform image display is realized over the entire image display area.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an embodiment of the present invention.

FIG. 2 is a diagram showing a waveform of a voltage corrected based on the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display panel, 2 ... Driver IC, 3 ... Driver IC, 4 ... Driver control circuit, 5 ... Fluorescent lamp (line light source), 6 ... Temperature sensing element, 7 ... temperature sensing element, 8 ... temperature comparison circuit, 9 ... voltage correction circuit (voltage correction means).

Claims (1)

[Claims] 1. A liquid crystal display panel having a substrate on which electrodes are formed facing each other, a backlight unit disposed on the back side of the liquid crystal display panel and having a light source and a light guide plate, one side of the liquid crystal display panel, or A plurality of driver ICs arranged along two sides facing each other and supplying a signal voltage to each electrode; and a plurality of driver ICs arranged along the other side of the liquid crystal display panel or the other two sides facing each other. And a plurality of driver ICs for supplying a scanning voltage, wherein a temperature distribution around the liquid crystal display panel is detected and supplied to each electrode via each driver IC based on the detected temperature distribution. A liquid crystal display device comprising a voltage correcting means for individually adjusting a scanning voltage to be applied.