CN101505559A - Temperature control system of backlight module - Google Patents

Abstract

The invention relates to a temperature control system of a backlight module, which is applied to the backlight module for increasing the brightness of a liquid crystal display by directly increasing the quantity of light sources of the backlight unit.

Description

Temperature control system of backlight module

technical field

The invention relates to a temperature control system of a backlight module, in particular to a temperature control system which detects the resistance value of a thermistor so that a control circuit can timely lower the luminance of the backlight module.

Background technique

Liquid crystal is an organic compound between solid and liquid. It is also a compound with standardized molecular arrangement. When heated above a certain temperature, it will become a transparent liquid, and when it is cooled below a certain temperature, it will become a transparent liquid. The turbid solid state of the crystal is called liquid crystal because of its characteristic. Due to the basic characteristics of liquid crystals, the basic principle of liquid crystal displays is to seal the liquid crystal in a glass box, and then apply an electric field to change the orientation of the liquid crystal molecules. The change in orientation will change the optical properties, and it can be changed through the polarizer. Translucency, to achieve bright and dim effect.

However, when the liquid crystal display is used as a display board under sunlight or bright ambient light, the color of the display is often lightened because the reflected light is too strong or the scattered light is too messy, and the picture is not clear or visible. Because the brightness of the display itself is not enough, the screen image is covered by external reflected light or scattered light. At least the brightness of the LCD display must be increased to ^above 1000cd/m2 to improve the problem of the screen being covered by the ambient light source.

To improve the brightness of the LCD, increasing the number of light sources in the backlight unit is the most direct method. If it can be equipped with high-efficiency reflective sheets, brightening sheets, and high-aperture liquid crystal panels, the utilization rate of light can also be increased, so as to achieve High brightness effect.

However, the light source itself will generate heat when emitting light. The more the number of light sources, the higher the total heat generated. As the lighting time of the backlight unit increases, the temperature of the entire liquid crystal display module will also become higher and higher, resulting in product failure. Overheating, lower display contrast, and even electronic components cannot work due to overheating, resulting in crashes.

It should be noted that the existing liquid crystal display cannot be processed due to high temperature, so the brightness of most liquid crystal display products on the market is about 300cd/m ² , with a semi-reflective design, or without a backlight unit, simply The problem of light reflection from external light sources is overcome by means of a total reflection liquid crystal display. However, these methods also cause the color number of the screen of the semi-reflective liquid crystal display to decrease, the color purity is not high, and the image quality is affected, and the total reflection product cannot be displayed in places with insufficient light.

Contents of the invention

Therefore, in order to solve the above-mentioned defects and avoid the existence of defects, the main purpose of the present invention is to increase the number of light sources to greatly increase the brightness of the backlight module, by adjusting the light brightness of the light sources to avoid continuous accumulation of heat from the light sources, Related materials and electronic components can be avoided, and the performance or lifespan will not be reduced due to excessive temperature, and the lifespan of the liquid crystal module will be increased.

Based on the above purpose, the present invention proposes a temperature control system for a backlight module, which is applied to a backlight module that directly increases the number of light sources of the backlight unit to increase the brightness of a liquid crystal display, and at least includes: a light emitting module for providing brightness of the backlight module group; at least one thermistor used to sense the temperature of the backlight module; and a control circuit, which receives the change signal of the resistance value of the thermistor to control the brightness output of the light emitting module, thereby adjusting the temperature of the backlight module Generated, the temperature increase rate slows down and gradually decreases.

The light-emitting module is composed of multiple light-emitting diodes (Light Emitting Diode; LED) or cold cathode fluorescent lamps (Cold Cathode Fluorescent Lamp, CCFL), and the control circuit is composed of pulse width modulation (Pulse Width Modulation, PWM ) way to control the brightness of the light-emitting module.

And when the control circuit receives that the resistance value of the thermistor is lower than the reference value, the luminous brightness of the light-emitting module is lowered; when the control circuit receives the resistance value of the thermistor is higher than the reference value, the The light-emitting brightness of the light-emitting module is to supply the power that the light-emitting module should have, and maintain the light-emitting brightness that the light-emitting module should have.

The effect of the present invention is that for the structure of the backlight module that increases the number of light sources of the backlight unit to increase the brightness of the liquid crystal display, the present invention detects the resistance value of the thermistor and matches the pulse width modulation of the control circuit to realize timely Lowering the luminance of the light-emitting module makes the temperature increase of the backlight unit slow down and decrease gradually. It can avoid the continuous accumulation of heat generated by the light-emitting module, causing the temperature of the entire Liquid Crystal Display Module (LCM) to rise continuously, making it unable to operate normally. Reduced performance or shortened life due to temperature.

Description of drawings

FIG. 1 is a schematic diagram of a temperature control system of an embodiment of the present invention.

FIG. 2 is a flow chart of the judgment of the resistance value by the control circuit of the embodiment of the present invention.

Detailed ways

The detailed content and technical description of the present invention will be further described by examples, but it should be understood that these examples are for illustrative purposes only, and should not be construed as limitations on the implementation of the present invention.

To increase the brightness of the LCD module, increasing the number of light sources in the backlight unit is the most direct method, so a large number of light sources are built in the backlight unit to greatly increase the brightness of the LCD module (LCM), but there will always be The higher the heat, especially the heat generated by the light source, as the lighting time of the backlight unit increases, the temperature of the entire liquid crystal display module will also become higher and higher, resulting in hot products, lower display contrast, and even It causes electronic components to fail to work due to overheating, resulting in a crash.

Please refer to Fig. 1, so the temperature control system of the backlight module proposed by the present invention is applied to the backlight module directly increasing the number of light sources to improve the brightness of the liquid crystal display, and it at least includes: a control circuit 10, and the control circuit 10 is A light-emitting module 12 is controlled by pulse width modulation (PWM), wherein the light-emitting module 12 is composed of a plurality of light-emitting diodes or cold cathode fluorescent tubes to provide the brightness of the backlight module. And, at least one thermistor 11 is used to sense the temperature of the backlight module, and the thermistor 11 will transmit the change signal of its resistance value to the control circuit 10, so that the control circuit 10 can be used to control and adjust the light emission The brightness output of the module adjusts the temperature change of the backlight module, so that the temperature increases slowly and decreases gradually.

The surface brightness of the backlight module increases or decreases with the increase or decrease of the number of light sources on the light emitting module 12 . For example, when the backlight module includes 64 light-emitting diode (LED) light-emitting chips as the light source, the surface brightness of the backlight module is 30780cd/m ² , which can make the surface brightness of the liquid crystal display module (LCM) As high as 3388cd/m ² , such a high brightness can be used as a display panel to improve the problem that the display screen is covered by ambient light sources in the environment of sunlight or bright ambient light.

Please refer to FIG. 2 again, as the lighting time of the light-emitting source on the light-emitting module 12 increases, the heat generated by the light-emitting module 12 will continue to accumulate, causing the temperature of the backlight module to gradually rise, and the liquid crystal display module ( LCM) temperature also rises accordingly. At this time, the resistance value of the thermistor 11 is detected, and the resistance value is transmitted to the control circuit 10. When the resistance value of the thermistor 11 is lower than a predetermined reference value, it indicates that the temperature of the backlight module is too high. , the control circuit 10 lowers the luminous brightness of the light emitting module 12 by adjusting the pulse width, so as to reduce the heat of the light emitting module 12, and make the temperature increase of the backlight unit slow down and gradually decrease. Thereby, it can be avoided that the heat generated by the light-emitting module 12 continues to accumulate, causing the temperature of the entire liquid crystal module (LCM) to rise continuously, so that it cannot operate normally. Reduced performance or shortened life.

However, when the control circuit 10 receives the resistance value signal of the thermistor 11 higher than the predetermined reference value, it means that the temperature of the backlight module is not too high or has dropped to a reasonable range, then the control circuit 10 maintains the normal temperature. The pulse width of the light emitting module 12 is supplied with the proper power output to maintain the proper luminous brightness of the light emitting module 12 without adjusting the luminous brightness of the light emitting module 12 .

For the device that directly increases the number of light sources of the backlight unit to increase the surface brightness of the liquid crystal display module (LCM), the more the number of light sources, the higher the total heat generated. The present invention detects the resistance value of the thermistor. Combined with the pulse width modulation of the control circuit, the luminous brightness of the light-emitting module can be lowered in a timely manner, which can slow down the temperature increase of the backlight unit and gradually decrease, so as to avoid the continuous accumulation of heat generated by the light-emitting module, causing the entire The liquid crystal module cannot operate normally, which increases the service life of the liquid crystal module, and at the same time avoids related materials and electronic components, and will not reduce performance or shorten life due to excessive temperature.

The foregoing are only preferred embodiments of the present invention, and are not intended to limit the implementation scope of the present invention. That is, all equivalent changes and modifications made according to the patent scope of the present invention are covered by the patent scope of the present invention.

Claims (5)

1. A temperature control system of a backlight module, characterized in that it at least includes: A light emitting module (12), used to provide the brightness of the backlight module; At least one thermistor (11), used to sense the temperature change of the backlight module; and a control circuit (10), which receives the change signal of the resistance value of the thermistor (11), and is used to control the light emission The brightness output of the module (12), thereby adjusting the temperature of the backlight module. 2. The temperature control system according to claim 1, characterized in that, the light emitting module (12) is composed of a plurality of light emitting diodes. 3. The temperature control system according to claim 1, characterized in that, the light emitting module (12) is composed of a plurality of cold cathode fluorescent tubes. 4. The temperature control system according to claim 1, characterized in that, the control circuit (10) controls the brightness of the light emitting module (12) by way of pulse width modulation. 5. The temperature control system according to claim 1, characterized in that, when the control circuit (10) receives that the resistance value of the thermistor (11) is lower than a reference value, the light-emitting mode is lowered. The luminous brightness of the group (12); when the control circuit (10) receives that the resistance value of the thermistor (11) is higher than a reference value, the luminous brightness of the luminous module (12) is not adjusted.

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