TWI383354B - Structure of feedback and method of driving for stabilizing brightness of the screened board - Google Patents

Description

Display device capable of stable brightness

The present invention relates to a feedback technique, and more particularly to a driving method for stabilizing the brightness of a display panel and a feedback device therefor.

With the booming development of the optoelectronic industry, the traditional image tube screen has been replaced by LCD screens or plasma TVs because of its excessive size. Together with computers, it is one of the important tools for modern people to go to work and at home, so LCD The screen has also become an indispensable technology product. The liquid crystal screen comprises a backlight module, and the backlight module needs a light source. Generally, the light source may be one of a cold cathode fluorescent tube and a hot cathode fluorescent tube, a light emitting diode and an electric excitation light sheet.

If the light source is a light-emitting diode, a multi-block LED backlight technology is usually used, because the use of this technology can not only increase the color range, wide angle, contrast and power saving of the liquid crystal module. It is also possible to adjust the gray scale of the display and reduce the brightness of the backlight module. However, since the backlight module with the backlight of the light-emitting diode is degraded due to the influence of thermal effects under a long period of operation, the luminance and chromaticity of the display cannot be stabilized. Although a light sensor can be disposed in each block on a panel, the light sensor is used to detect light and correct the brightness of each block, but the cost is too high and it is difficult to achieve in production. If only one light sensor is set, it will affect the light type except for the placement position.

Furthermore, as shown in FIG. 1, a photo sensor 12 is disposed on a display panel 10, and is detected by a light-emitting block 14 that is far away and has a low brightness at that time. The brightness is not accurate. In addition, if the brightness of each block is continuously detected in a short time under the same brightness, each light-emitting diode must increase the current to compensate for the difference in brightness, but in this way, the luminous efficiency of the light-emitting diode It will be reduced and will not meet market demand.

Therefore, the present invention is directed to the above-mentioned problems, and provides a driving method for stabilizing the brightness of the display panel and a feedback device thereof, which can not only avoid higher cost, but also can improve the panel without increasing the number of photodetectors. Brightness stability.

The main object of the present invention is to provide a driving method for stabilizing the brightness of a display panel and a feedback device thereof, which can effectively stabilize the brightness, chromaticity and brightness of the display panel.

Another object of the present invention is to provide a driving method for stabilizing the brightness of a display panel and a feedback device thereof, which can save the cost of the backlight module in the display.

Still another object of the present invention is to provide a driving method for stabilizing the brightness of a display panel and a feedback device thereof, which can reduce the number of use of the photo sensor.

In order to achieve the above object, the present invention provides a feedback device for stabilizing the brightness of a display panel, comprising a plurality of light emitting diodes for providing a light source, and the light emitting diodes are electrically connected to at least one current/ The voltage detector is configured to detect a first electrical signal of each of the light emitting diodes, and a light sensor is disposed on a display panel for detecting one of each block on the display panel After the brightness, the brightness is converted into a second electrical signal, and the current/voltage detector is electrically connected to the photo sensor to a microprocessor to receive the first electrical signal and the second electrical signal. And using each of the first brightness values of the block to calculate a brightness change of each of the blocks, thereby adjusting currents of the light emitting diodes, and at least one driving circuit, wherein one end of the electrical The microprocessor is connected to the other end, and the other end is electrically connected to the light emitting diodes, and the driving circuit can provide currents required by the light emitting diodes to control the brightness of each of the blocks.

The invention also provides a driving method for stabilizing the brightness of the display panel, first recording a first brightness value of the plurality of blocks at the initial time on the display panel, wherein the first brightness value is calculated from an initial internal resistance of each of the light emitting diodes Then, using one of the operating parameters of each of the light-emitting diodes to obtain a second brightness value in each block operation, and then calculating the second brightness value and the first brightness value to know each block The amount of change in brightness.

For a better understanding and understanding of the structural features and the achievable effects of the present invention, please refer to the preferred embodiment and the detailed description.

The present invention is a driving method for stabilizing the brightness of a display panel and a feedback device thereof, which can be used to stabilize the brightness of the display panel, thereby stabilizing its chromaticity and luminance, so that these characteristics are not easily deteriorated due to long-term influence. In addition, the present invention can also achieve the above object while reducing the number of use of the photo sensor, which is more difficult.

The present invention can be applied to a display device capable of stabilizing brightness. The display device includes a display panel and a backlight module. The backlight module illuminates the display panel, and the backlight module is composed of the feedback device of the present invention. Its driving method works smoothly.

Please refer to FIG. 2, which is a schematic diagram of the feedback device of the present invention. The device includes a plurality of light emitting diodes 16 for providing a light source, and the light emitting diode 16 is electrically connected to a current/voltage detector 24, and the current/voltage detector 24 is used. Detecting a first electrical signal of each of the LEDs 16, such as a forward current and a forward voltage; and a photo sensor 22 for detecting the brightness of each of the blocks on a display panel Afterwards, the brightness is converted into a second electrical signal, and the photo sensor 22 can detect white light in addition to red, blue and green light; a microprocessor 18 is electrically connected to The current/voltage detector 24 and the photo sensor 22 are configured to receive the first electrical signal and the second electrical signal, and use the first brightness value of each block at the initial time to calculate the brightness change of each block. The driving circuit 20 is electrically connected to the microprocessor 18, and the other end is electrically connected to the LED 16 , and the driving circuit 20 can provide the LED 16 . The current required, in turn, controls the brightness of each block.

The present invention utilizes a driving method to operate the above-mentioned feedback device. Please refer to FIG. 3A at the same time. First, as shown in step S1, one of the first brightness values, the first brightness value, of the plurality of blocks on the display panel at the initial time is recorded. It can be calculated from the initial internal resistance of the light-emitting diode. Then, as shown in step S2, the current/voltage detector 24 is used to detect the obtained parameters of each of the light-emitting diodes 16, that is, the forward current and the forward voltage, to calculate one of the work of each block. The second brightness value. Then, in step S3, the brightness change amount of one of each block is calculated by using the second brightness value and the first brightness value.

As shown in step S4, it is determined whether the amount of change in brightness is fluctuating. If there is no change, the process returns to step S2. If there is a change, step S5 is performed, which calculates and adjusts the current required for the light-emitting diode 16. The current is reduced or increased according to the brightness requirement, and a counter on each block of the brightness variation is incremented by one. Then, in step S6, it is determined whether the counter reaches the preset value N. If not, the process returns to step S2. If yes, the light sensor 22 can be used to detect the brightness of a block in which the counter is located. And calculating a difference value by using the brightness and the first brightness value, and correcting the current of each of the light emitting diodes according to the difference value, as in step S7, and then returning to step S2. In addition, the counter may not be used. As shown in FIG. 5, if the LEDs 16 of each block are sequentially illuminated, a brightness is detected at the moment when the third block 32 is illuminated, but this is When the first block 28, the second block 30 and the fourth block 34 are not bright, a difference value is calculated by using the brightness and the first brightness value, and the current of each of the light-emitting diodes 16 is corrected according to the difference value.

Please continue to refer to FIG. 3B, and step S2 further includes steps S22 to S28. First, as shown in step S22, the current/voltage detector 24 detects the operating parameters of each of the LEDs 16; and then proceeds to step S24, which uses the operating parameters to calculate one of the operations of each of the LEDs 16. The internal resistance value is further performed in step 26. The relationship between the junction temperature and the internal resistance of each of the light-emitting diodes 16 and the internal resistance value is obtained as a junction temperature value of each of the light-emitting diodes 16 in operation, as shown in FIG. 4A. The final step S28 is to obtain the second brightness value of each block in operation by the relationship between the brightness value of the light-emitting diodes 16 and the junction temperature and the junction temperature value. See FIG. 4B. In addition, in step S2, the second brightness value in each block operation can be obtained one by one or one by one group block detection, so that the photo sensor 22 is not needed for each block. For a short time to detect. In summary, the present invention can stabilize the brightness of the display panel, thereby stabilizing the luminance and chromaticity thereof, and can achieve the above purpose while reducing the number of use of the photo sensor, thereby saving the backlight module in the display. the costing payment. Moreover, in the present invention, there is no need to worry about the problem that the brightness of the remote block is too weak, because the light sensor can be detected by waiting for the brightness of the block to be above a proper brightness.

The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, so that the shapes, structures, features, and spirits described in the claims of the present invention are equally varied and modified. All should be included in the scope of the patent application of the present invention.

10. . . Display panel

12. . . Light sensor

14. . . Illuminated block

16. . . Light-emitting diode

18. . . microprocessor

20. . . Drive circuit

twenty two. . . Light sensor

twenty four. . . Current/voltage detector

26. . . Display panel

28. . . First block

30. . . Second block

32. . . Third block

34. . . Fourth block

36. . . Light sensor

FIG. 1 is a schematic diagram of a conventional technique for detecting each block on a display panel.

Figure 2 is a schematic diagram of the circuit of the device of the present invention.

3A and 3B are flow charts of the method of the present invention.

Fig. 4A is a graph showing the relationship between the internal resistance of the light-emitting diode and the junction temperature.

Fig. 4B is a graph showing the relationship between the luminance value of the light-emitting diode and the junction temperature.

FIG. 5 is a schematic diagram of detecting blocks in a display panel according to the present invention.

16. . . Light-emitting diode

18. . . microprocessor

20. . . Drive circuit

twenty two. . . Light sensor

twenty four. . . Current/voltage detector

Claims (10)

A display device capable of stabilizing brightness, the device comprising: a display panel; and a backlight module for illuminating the display panel, wherein the backlight module comprises: a plurality of LEDs, which are used Providing a light source; at least one current/voltage detector electrically connected to the light emitting diodes, and detecting a first electrical signal of each of the light emitting diodes; and a light sensing The device is used to detect the brightness of one of each block on a display panel and convert the brightness into a second electrical signal; a microprocessor electrically coupled to the current/voltage detector and The light sensor can receive the first electrical signal and the second electrical signal to calculate a brightness change amount of each of the blocks, and adjust currents of the light emitting diodes; and at least one driving circuit, wherein one end The other end is electrically connected to the light emitting diodes, and the driving circuit can provide currents required by the light emitting diodes to control the brightness of each of the blocks. The display device capable of stabilizing brightness according to claim 1, wherein the first electrical signal comprises: a forward current and a forward voltage. The display device of claim 1 , wherein the light color detected by the light sensor is white. The display device capable of stabilizing brightness according to claim 1, wherein the brightness change amount includes a first change amount and a second change amount. The display device of claim 4, wherein the first amount of change is calculated from a first brightness value of each of the blocks and the first electrical signal. The display device of claim 4, wherein the second amount of change is calculated by one of the first brightness values and the second electrical signal at the beginning of each of the blocks. The display device capable of stabilizing brightness according to claim 1, wherein the internal resistance value of each of the light-emitting diodes can be calculated by using the first electrical signal. The display device capable of stabilizing brightness according to claim 7, wherein the internal resistance value and the relationship between the internal resistance value of each of the light-emitting diodes and the junction temperature are obtained for each of the light-emitting diodes. A junction temperature value. The display device capable of stabilizing brightness according to claim 8, wherein the junction temperature value and the relationship between the brightness value of each of the light-emitting diodes and the junction temperature are used to obtain one of each of the blocks. Two brightness values. A display device capable of stabilizing brightness according to claim 4, wherein the number of times the first variation is varied is calculated by a counter on each of the blocks.