KR102332277B1 - Liquid Crystal Display Device - Google Patents

Abstract

The present invention provides a liquid crystal display device including a liquid crystal panel, a data driver, a timing controller, and a sensing circuit. The liquid crystal panel displays an image. The data driver supplies a data signal to the liquid crystal panel. The timing controller controls the data driver. The sensing circuit unit senses the temperature of the data driver and outputs a control signal based on the sensed temperature information. The data driver changes the inversion method in response to the control signal.

Description

Liquid Crystal Display Device

The present invention relates to a liquid crystal display device.

As information technology develops, the market for display devices, which is a connection medium between users and information, is growing. Accordingly, a Flat Panel Display (FPD) such as a Liquid Crystal Display (LCD), an Organic Light Emitting Diode Display (OLED), and a Plasma Display Panel (PDP). ) is on the rise. Among them, a liquid crystal display capable of realizing a high resolution and capable of being miniaturized as well as enlarged is widely used.

The liquid crystal display device includes a liquid crystal panel including a plurality of sub-pixels arranged in a matrix form, a driving unit for outputting a driving signal for driving the liquid crystal panel, and a power supply unit for generating power to be supplied to at least one of the liquid crystal panel and the driving unit. .

The liquid crystal panel includes a liquid crystal layer positioned between a transistor substrate on which a thin film transistor, a storage capacitor, and a pixel electrode are formed, and a color filter substrate on which a color filter and a black matrix are formed.

The driver includes a gate driver that supplies a gate signal (or scan signal) to the liquid crystal panel and a data driver that supplies a data signal to the liquid crystal panel. In the above-described display device, when a driving signal, for example, a gate signal and a data signal, is supplied to the sub-pixels formed in the liquid crystal panel, the light provided from the backlight unit is transmitted through the selected sub-pixel to display an image.

In the liquid crystal display described above, the power consumption of the data driver is increasing due to the recent increase in the size and resolution of the liquid crystal panel. The increase in power consumption of the data driver has a close relationship with heat generation of the data driver. That is, when the power consumption increases, the heat generation of the data driver also increases as much as the increased power consumption.

For this reason, in the prior art, a method of performing heat dissipation treatment of the device by attaching a heat dissipation pad or resin to reduce heat generation of the data driver has been proposed. However, the method of attaching a heat dissipation pad or resin causes cost increases such as cost and processing cost. And above all, this method is difficult to lower the temperature and power consumption of the device in relation to the temperature or driving characteristics of the device, so improvement is required.

The present invention for solving the problems of the above-described background technology lowers the temperature and power consumption of the device in relation to the temperature or driving characteristics of the device, maintains the display quality of the screen uniformly during the compensation operation, and reduces heat generation due to the increase in load and to prevent the drop of the input voltage.

As a means of solving the above problems, the present invention provides a liquid crystal display device including a liquid crystal panel, a data driver, a timing controller, and a sensing circuit. The liquid crystal panel displays an image. The data driver supplies a data signal to the liquid crystal panel. The timing controller controls the data driver. The sensing circuit unit senses the temperature of the data driver and outputs a control signal based on the sensed temperature information. The data driver changes the inversion method in response to the control signal.

The data driver selects one of the first polarity control signal provided from the timing controller and the second polarity control signal set therein in response to the control signal and outputs it as a third polarity control signal, and outputs the third polarity control signal to its own digital analog It may include an inversion change unit that supplies the conversion unit.

The sensing circuit unit may include a temperature sensor unit that is formed inside the data driver and outputs temperature information, and a control signal output unit that outputs a different control signal for each temperature range based on the temperature information.

The data driver may perform a vertical two-dot inversion operation when its own temperature is lower than the reference temperature, and may perform a column inversion operation if its own temperature is higher than the reference temperature.

In another aspect, the present invention provides a liquid crystal display including a liquid crystal panel, a backlight unit, a data driver, a timing controller, and a sensing circuit. The liquid crystal panel displays an image. The backlight unit supplies light to the liquid crystal panel. The data driver supplies a data signal to the liquid crystal panel. The timing controller controls the data driver. The sensing circuit unit senses the temperature of the data driver and outputs a control signal based on the sensed temperature information. The timing controller outputs a signal for changing the luminance of the backlight unit along with the grayscale of the data signal in response to the control signal.

When the temperature of the data driver increases, the timing controller may output a compensation data signal for lowering the gray level of the data signal and output a compensation dimming signal for increasing luminance of the backlight unit.

In another aspect, the present invention provides a liquid crystal display device including a liquid crystal panel, a data driving unit, a power supply unit, a timing control unit and a sensing circuit unit. The liquid crystal panel displays an image. The data driver supplies a data signal to the liquid crystal panel. The power supply unit supplies a common voltage to the liquid crystal panel. The timing controller controls the data driver. The sensing circuit unit senses the temperature of the power supply unit and outputs a control signal based on the sensed temperature information. The power supply unit changes a gain for compensating and generating the common voltage in response to the control signal.

The power supply unit includes an amplifying unit having a first terminal connected to a variable common voltage line to which a variable common voltage is transmitted and a second terminal connected to a feedback common voltage line through which a feedback common voltage is transmitted, and one end connected to a feedback common voltage line and amplified. A first resistor unit having the other end connected to the negative second terminal, a second resistor unit having one end connected to the second terminal of the amplifying unit and the other end connected to the third terminal of the amplifying unit, and a second resistance unit based on a control signal and an internal reference voltage and a common voltage generator having a gain selector outputting a gain select signal for changing the resistance value of the resistor unit.

The second resistor unit may include a switch group and a resistor group having a parallel connection structure, and the resistance value of the second resistor unit may be varied as on and off states of switches of the switch group are changed in response to a gain selection signal.

In another aspect, the present invention provides a liquid crystal display device including a liquid crystal panel, a backlight unit, a data driving unit, a power supply unit, a timing control unit and a sensing circuit unit. The liquid crystal panel displays an image. The backlight unit supplies light to the liquid crystal panel. The data driver supplies a data signal to the liquid crystal panel. The power supply unit supplies a common voltage to the liquid crystal panel. The timing controller controls the data driver. The sensing circuit unit includes a first temperature sensor unit formed in the data driving unit, a second temperature sensor unit formed in the power supply unit, and first to second temperature information output from the first and second temperature sensor units. and a control signal output unit for outputting at least one of the three control signals. The data driver changes the inversion method in response to the first control signal, the timing controller outputs a signal for changing the luminance of the backlight unit along with the grayscale of the data signal in response to the second control signal, and the power supply unit provides the third control signal. The gain for compensating and generating the common voltage is changed in response to the control signal.

In the present invention, since the data driver performs temperature compensation by itself in response to a change in temperature, individual control of the data driver is possible, heat generation can be reduced, and power consumption can also be reduced. In addition, since the present invention performs the compensation operation under the mutual interlocking of the devices driving the liquid crystal panel, it is possible to perform the compensation more sensitively and stably even to a small temperature change. In addition, according to the present invention, since the compensation operation is performed under the interlocking of the device driving the liquid crystal panel, the display quality of the screen can be uniformly maintained even during the compensation operation. Also, according to the present invention, heat generation due to an increase in the load of the common voltage occurring in a special pattern can be eliminated, and the shutdown of the device (IC Shut Down) and the drop of the input voltage supplied to the power supply can be prevented.

1 is a block diagram schematically showing a liquid crystal display device;
FIG. 2 is a circuit diagram schematically illustrating the sub-pixel shown in FIG. 1;
3 to 5 are views schematically showing the configuration of a compensation circuit according to the first to third embodiments of the present invention.
6 is a view for explaining a compensation concept according to embodiments of the present invention.
7 is a diagram illustrating a configuration of a data driver having a compensation circuit and a liquid crystal display using the same according to the first embodiment of the present invention.
8 is an exemplary configuration diagram of a temperature sensor unit;
9 is a block diagram illustrating a part of a data driving unit;
10 is an exemplary diagram of an inversion method according to the first embodiment of the present invention.
11 is a relationship diagram illustrating a relationship between a temperature and a compensation scheme.
12 is a flowchart of a compensation method according to the first embodiment of the present invention;
13 is a view for explaining a temperature change according to a change in a special pattern and an inversion method displayed on the liquid crystal panel;
14 is a diagram illustrating a configuration of a data driver having a compensation circuit and a liquid crystal display using the same according to a second embodiment of the present invention;
15 is a relationship diagram illustrating a relationship between a temperature and a compensation scheme.
16 is a flowchart of a compensation method according to a second embodiment of the present invention;
17 is a diagram for explaining a change in a signal by a compensation method according to a second embodiment of the present invention;
18 is a diagram illustrating a configuration of a power supply unit having a compensation circuit and a liquid crystal display using the same according to a third embodiment of the present invention;
19 is a schematic configuration diagram of a common voltage generator;
20 is a detailed configuration diagram of a common voltage generator;
21 is a relationship diagram illustrating a relationship between a compensation step and a compensation method;
22 is a relationship diagram showing a relationship between a temperature and a compensation scheme;
23 is a diagram illustrating a configuration of a power supply unit having a compensation circuit and a liquid crystal display using the same according to a fourth embodiment of the present invention.

Hereinafter, specific details for carrying out the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram schematically illustrating a liquid crystal display, and FIG. 2 is a circuit diagram schematically illustrating a sub-pixel illustrated in FIG. 1 .

1 and 2, the liquid crystal display includes an image supply unit 110, a timing control unit 130, a gate driving unit 140, a data driving unit 150, a liquid crystal panel 160, a backlight unit 170 and A power supply unit 180 is included.

The image supply unit 110 outputs various driving signals together with an image data signal supplied from the outside or an image data signal stored in an internal memory. The image supply unit 110 supplies a data signal and various driving signals to the timing control unit 130 .

The timing controller 130 outputs a gate timing control signal GDC for controlling the operation timing of the gate driver 140 and a data timing control signal DDC for controlling the operation timing of the data driver 150 . The timing controller 130 supplies the data signal (or data voltage) DATA supplied from the image processor 110 together with the data timing control signal DDC to the data driver 150 .

The gate driver 140 outputs a gate signal while shifting the level of the gate voltage in response to the gate timing control signal GDC supplied from the timing controller 130 . The gate driver 140 supplies a gate signal to the sub-pixels SP included in the liquid crystal panel 160 through the gate lines GL. The gate driver 140 is formed in the form of an integrated circuit (IC) or is formed in the liquid crystal panel 160 in the form of a gate in panel.

The data driver 150 samples and latches the data signal DATA in response to the data timing control signal DDC supplied from the timing controller 130 , converts it into an analog signal form corresponding to the gamma reference voltage, and outputs it. The data driver 150 supplies the data signal DATA to the sub-pixels SP included in the liquid crystal panel 160 through the data lines DL. The data driver 150 is formed in the form of an integrated circuit (IC).

The liquid crystal panel 160 displays an image corresponding to the gate signal supplied from the gate driver 140 , the data signal DATA supplied from the data driver 150 , and the common voltage VCOM supplied from the power supply unit 180 . do. The liquid crystal panel 160 includes sub-pixels SP that control the light provided through the backlight unit 170 .

One sub-pixel includes a switching transistor SW, a storage capacitor Cst, and a liquid crystal layer Clc. The gate electrode of the switching transistor SW is connected to the gate line GL1 , and the source electrode is connected to the data line DL1 . One end of the storage capacitor Cst is connected to the drain electrode of the switching transistor SW and the other end is connected to the common voltage line Vcom. The liquid crystal layer Clc is formed between the pixel electrode 1 connected to the drain electrode of the switching transistor SW and the common electrode 2 connected to the common voltage line Vcom.

The liquid crystal panel 160 has a TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In Plane Switching) mode, FFS (Fringe Field Switching) mode depending on the structure of the pixel electrode 1 and the common electrode 2 . Alternatively, it is implemented in an Electrically Controlled Birefringence (ECB) mode.

The backlight unit 170 provides light to the liquid crystal panel 160 using a light source that emits light. The backlight unit 170 includes a light emitting diode (hereinafter LED), an LED driving unit for driving the LED, an LED board on which the LED is mounted, a light guide plate for converting the light emitted from the LED into a surface light source, a reflector for reflecting the light from the lower part of the light guide plate, and optical sheets for condensing and diffusing the light emitted from the light guide plate.

The power supply unit 180 generates and outputs power to be supplied to one or more of the timing controller 130 , the gate driver 140 , the data driver 150 , and the liquid crystal panel 160 based on an input voltage supplied from the outside. have. For example, the power supply unit 180 may include a common voltage VCOM, a first power voltage VCC, and a second power voltage GND, but is not limited thereto.

In the liquid crystal display device described above, power consumption of the data driver 150 or the power supply unit 180 is increasing due to an increase in the size and resolution of the liquid crystal panel in recent years. An increase in power consumption of the data driving unit 150 or the power supply unit 180 has a close relationship with heat generation of the data driving unit 150 or the power supply unit 180 . That is, when the power consumption increases, the heat of the data driver 150 or the power supply unit 180 also increases as much as the increased power consumption.

For this reason, in the prior art, a method of performing heat dissipation treatment of the device by attaching a heat dissipation pad or resin to reduce heat generation of the data driver has been proposed. However, the method of attaching a heat dissipation pad or resin causes cost increases such as cost and processing cost.

3 to 5 are diagrams schematically showing the configuration of a compensation circuit according to the first to third embodiments of the present invention, and FIG. 6 is a diagram for explaining the compensation concept according to the embodiments of the present invention.

As shown in FIG. 3 , according to the first embodiment of the present invention, the data driver 150 corresponds to the control signal CS output from the sensing circuit unit 190 , in response to the first to Nth (N is an integer greater than or equal to 4). ) Perform compensation inversion (INVC) using the inversion (INV 1 ~ INV N) method or change the inversion method compared to the previous one.

As shown in FIG. 4 , according to the second embodiment of the present invention, the timing control unit 130 compensates the data signal and the dimming signal in response to the control signal CS output from the sensing circuit unit 190 and compensates the data signal. (DATAC) and the compensation dimming signal (DIMC) are output.

As shown in FIG. 5 , according to the third embodiment of the present invention, the power supply unit 180 compensates for the common voltage in response to the control signal CS output from the sensing circuit unit 190 and compensates the common voltage VCOMC. to output

In addition, although not shown, if the first to third embodiments described above are properly combined and combined, all of (1) changing the inversion method, (2) changing the compensation data signal and the compensation dimming signal, and (3) changing the common voltage can be utilized

3 to 5 , the sensing circuit unit 190 includes a temperature sensor unit 192 and a control signal output unit 195 . The temperature sensor unit 192 senses the temperature of the device and transmits the sensed temperature information TMP to the control signal output unit 195 . The control signal output unit 195 outputs a digital or analog control signal CS based on the temperature information TMP. In particular, the control signal output unit 195 may be configured to output a control signal CS corresponding thereto for each specific temperature range in response to a lookup table set therein.

As shown in FIG. 6 , when a specific (or special) pattern that induces heat is displayed on the liquid crystal panel, the temperature of the device (data driving unit or power supply unit) rises. However, since the protection or compensation operation is performed by the operation of the compensation circuit, the temperature of the device (data driving unit or power supply unit) does not rise any more and gradually decreases.

As described above, the embodiments of the present invention link a compensation circuit capable of performing an OTP (Over Temperature Protection) function and a device vulnerable to heat, and reduce the temperature and power consumption of the device in relation to the temperature or driving characteristics of the device. is configured as follows.

<First embodiment>

7 is a diagram illustrating the configuration of a data driver having a compensation circuit and a liquid crystal display using the same according to the first embodiment of the present invention, FIG. 8 is a diagram illustrating the configuration of a temperature sensor, and FIG. It is a block diagram, FIG. 10 is an exemplary diagram of an inversion method according to the first embodiment of the present invention, and FIG. 11 is a relationship diagram illustrating a relationship between a temperature and a compensation method.

7 to 11 , in the liquid crystal display according to the first embodiment of the present invention, compensation circuits 192 and 195 are provided in the data driver 150 . The data driver 150 includes a temperature sensor unit 192 , a control signal output unit 195 , an inversion change unit 158 , and a data conversion unit 159 (or a digital-to-analog conversion unit). The inversion change unit 158 is a compensation circuit added to the data output circuit unit 157 as the compensation circuits 192 and 195 are included in the data driver 150 .

The compensation circuits 192, 195, and 158 perform compensation inversion when the temperature increases as the data driver 150 outputs a data signal for displaying a special pattern, etc. on the liquid crystal panel or change the inversion method compared to the previous one. implemented to do

The temperature sensor unit 192 includes, for example, a sensing transistor TS, a comparator CMP, and It may be formed of a resistor (Rs). The comparator CMP compares the voltage (or current) of the first terminal (+) to which the sensing transistor TS is connected and the voltage (or current) of the second terminal (-) to which the resistor Rs is connected, and The result value (voltage or current) is transmitted to the control signal output unit 195 . The resulting value (voltage or current) is defined as temperature information (TMP).

The control signal output unit 195 detects a temperature change of the data driver 150 based on the temperature information TMP transmitted from the temperature sensor unit 192, and generates a control signal CS in response to the temperature change. This is transmitted to the inversion change unit 158 .

The inversion change unit 158 performs compensation inversion in an optimal driving method capable of lowering the temperature of the data driver 150 and increasing the image quality based on the control signal CS transmitted from the control signal output unit 195 . Or, the inversion method will be changed compared to the previous one.

The inversion change unit 158 includes, for example, an inversion selection unit INV SEL. The inversion selector INV SEL selects one of the first polarity control signal POL1 provided from the timing controller and the user or the second polarity control signal POL2 set therein in response to the control signal CS to select a third It is output as a polarity control signal (POL3).

The third polarity control signal POL3 output from the inversion change unit 158 is a MUXX located at the rear end of the positive decoder P-DAC and the negative decoder N-DAC of the data conversion unit 159 . can be transmitted to The positive decoder (P-DAC) is a circuit that converts a data signal to a positive voltage, and the negative decoder (N-DAC) is a circuit that converts a data signal to a negative voltage.

The data signal is changed into a positive voltage data signal (+) and a negative voltage data signal (-) by a positive decoder (P-DAC) and a negative decoder (N-DAC) and amplified through the buffer unit BUFF. It is output through the raw channels (CH1 ~ CH384). Meanwhile, in FIG. 9 , only the data conversion unit 159 related to the inversion change unit 158 is illustrated, while the shift register or latch present in the data output circuit unit 157 of the data driver 150 is omitted. .

According to the operations of the inversion changer 158 and the data converter 159 , the shape of the data voltage output from the channels CH1 to CH384 of the data driver 150 varies according to temperature as shown in FIG. 10 .

In the case of FIG. 10 , the first polarity control signal POL1 is provided for the data driver to perform vertical two-dot inversion, and the second polarity control signal POL2 for the data driver to perform column inversion. A case prepared to do this has been described as an example. In addition, the control signal CS has been described as an example of simply outputting a logic low (L) or logic high (H) signal according to a change in temperature, such as an OTP output.

As can be seen from the table of FIG. 10 , the data driver 150 may generate the data voltage in a V2Dot inversion method under the control of the timing controller. However, when the temperature increases, the inversion method may be changed to generate the data voltage using the column inversion method.

In the above description, the control signal (CS) or the polarity control signals (POL1 ~ POL3) are limited to show a simple example, but the present invention provides a different control signal ( CS) and the polarity control signals POL1 to POL3 may also be varied in various forms, but are not limited thereto.

Therefore, the present invention performs compensation inversion in the first to Nth (N is an integer greater than or equal to 4) inversion (INV 1 to INV N) method in response to temperature change as shown in FIG. 11 or to change the inversion method compared to the previous method. is implemented

Hereinafter, a compensation method according to a first embodiment of the present invention will be described.

12 is a flowchart of a compensation method according to a first embodiment of the present invention, and FIG. 13 is a view for explaining a temperature change according to a change in a special pattern and an inversion method displayed on the liquid crystal panel.

As shown in FIG. 12 , the temperature (IC temperature) of the data driver is sensed and compared with a reference temperature (OTP) set therein ( S110 ). At this time, if the temperature (IC temperature) of the data driver is lower than the reference temperature (OTP) (Yes), a logic low (0) is output, and if the temperature (IC temperature) of the data driver is higher than the reference temperature (OTP) (No) A logic high (1) may be output.

The data driver senses the temperature (IC temperature) and compares it with the internal reference temperature (OTP) (S120). If the temperature (IC temperature) of the data driver is lower than the reference temperature (OTP) (Yes), the data driver It is driven in a two-dot inversion (V2Dot inversion) method (S130). On the other hand, if the temperature (IC temperature) of the data driver is higher than the reference temperature (OTP) (No), the data driver is driven in a column inversion method ( S140 ).

As shown in FIG. 13 , the temperature change according to the change of the special pattern displayed on the liquid crystal panel and the inversion method according to the experimental results will be described as follows.

For example, as a result of displaying a white pattern on the liquid crystal panel using a vertical two-dot inversion method, the temperature of the data driver increased to 109°C. However, as a result of changing the inversion method to display a white pattern on the liquid crystal panel using the column inversion method, the temperature of the data driver dropped to 49 °C.

As another example, as a result of displaying a line-by-line 1-horizontal pattern H1 on the liquid crystal panel using a vertical 2-dot inversion method, the temperature of the data driver increased to 118°C. However, as a result of changing the inversion method to display one horizontal pattern (H1) of line-by-line on the liquid crystal panel using the column inversion method, the temperature of the data driver dropped to 105°C.

As can be seen from the above experimental results, in the first embodiment of the present invention, an inversion profile capable of lowering the temperature of the device is generated based on the correlation between the special pattern displayed on the liquid crystal panel and the inversion method, and it is then looked up. Devices and algorithms can be implemented to change the inversion in a corresponding way for each specific temperature range by tabulating it.

Therefore, in the first embodiment of the present invention, since the data driver controls its own output in response to a change in temperature, self-protection and compensation can be performed independently of other devices, making it easy to implement, low-cost and high-efficiency can get In addition, in the first embodiment of the present invention, since the data driver performs temperature compensation by itself, the circuit for recognizing the pattern of the timing controller is unnecessary, and thus the size thereof can be reduced. In addition, in the first embodiment of the present invention, as self-protection and compensation are performed, individual control of the data driver is possible, heat generation can be reduced, and power consumption can also be reduced.

<Second embodiment>

14 is a diagram illustrating a configuration of a data driver having a compensation circuit and a liquid crystal display using the same according to a second embodiment of the present invention, and FIG. 15 is a relationship diagram illustrating a relationship between temperature and compensation methods.

14 and 15 , in the liquid crystal display according to the second embodiment of the present invention, first compensation circuits 192 and 195 are provided in the data driver 150 , and the first compensation circuits 192 and 195 are provided in the timing controller 130 . Two compensation circuits 133 and 135 are provided.

The data driver 150 includes a temperature sensor unit 192 and a control signal output unit 195 . The temperature sensor unit 192 and the control signal output unit 195 are compensation circuits added separately from the data output circuit unit 157 included in the data driver 150 .

The first compensation circuits 192 and 195 output a control signal CS corresponding to the temperature when the temperature increases as the data driver 150 outputs a data signal for displaying a special pattern on the liquid crystal panel.

The temperature sensor unit 192 includes, for example, a sensing transistor TS and a comparator operating based on the first power voltage VCC and the second power voltage GND supplied to the inside of the data driver 150 as shown in FIG. 8 . (CMP) and a resistor (Rs). The comparator CMP compares the voltage (or current) of the first terminal (+) to which the sensing transistor TS is connected and the voltage (or current) of the second terminal (-) to which the resistor Rs is connected, and The result value (voltage or current) is transmitted to the control signal output unit 195 . The resulting value (voltage or current) is defined as temperature information (TMP).

The control signal output unit 195 detects a temperature change of the data driver 150 based on the temperature information TMP transmitted from the temperature sensor unit 192, and generates a control signal CS in response to the temperature change. This is transmitted to the timing controller 130 .

The timing controller 130 includes a data compensator 133 and a dimming compensator 135 . The data compensator 133 and the dimming compensator 135 are additionally configured to perform compensation operations on the data driver 150 and the backlight unit 170 in response to the signals transmitted from the first compensation circuits 192 and 195 . It is a compensation circuit that becomes

The data compensator 133 compensates the data signal in a form capable of lowering the temperature of the data driving unit 150 based on the control signal CS transmitted from the control signal output unit 195 and generates the compensation data signal DATAC. print out For example, the data compensator 133 lowers the grayscale of the data signal in units of N (N is an integer greater than or equal to 1) grayscale based on the control signal CS.

In addition, the dimming compensator 135 compensates the dimming value of the backlight unit 170 based on the control signal CS and the compensation data signal DATAC transmitted from the control signal output unit 195 and compensates for the compensation dimming signal DIMC. ) is output. For example, the dimming compensator 135 increases the luminance in units of M (M is an integer greater than or equal to 1) nits based on the control signal CS and the compensation data signal DATAC.

To add to the description, the compensation data signal DATAC is output in a state in which the gradation is lowered compared to the previous one in order to dissipate heat from the data driver. Therefore, the variation of the compensation dimming signal DIMC is used as a supplementary measure to compensate for image deviation that may appear in the entire liquid crystal panel due to the compensation operation by increasing the luminance by the lowered gray level. Therefore, when the temperature of the data driver is extremely high, the compensation dimming signal DIMC is output. However, when the temperature of the data driver is not too high compared to the reference temperature, the compensation dimming signal DIMC may be omitted.

Therefore, the present invention compensates the data signals DATA 1 to N and the dimming signals DIM 1 to N in response to the temperature change as shown in FIG. 15 and outputs the compensation data signal DATAC and the compensation dimming signal DIMC.

Hereinafter, a compensation method according to a second embodiment of the present invention will be described.

16 is a flowchart of a compensation method according to a second embodiment of the present invention, and FIG. 17 is a diagram for explaining a signal change by the compensation method according to the second embodiment of the present invention.

As shown in FIG. 16 , the temperature (IC temperature) of the data driver is sensed and compared with a reference temperature (OTP) set therein ( S210 ). At this time, if the temperature (IC temperature) of the data driver is lower than the reference temperature (OTP) (Yes), a logic low (0) is output, and if the temperature (IC temperature) of the data driver is higher than the reference temperature (OTP) (No) A logic high (1) may be output.

When the temperature (IC temperature) of the data driver is sensed and the result of comparison with the internally set reference temperature (OTP) (S220), the temperature (IC temperature) of the data driver is lower than the reference temperature (OTP) (Yes), the timing controller The same data signal and the like are output (original data) and the compensation operation is not performed (S230). On the other hand, if the temperature (IC temperature) of the data driver is higher than the reference temperature (OTP) (No), the timing controller uses the data compensator to lower the grayscale of the data signal (Panel Data ↓), and uses the dimming compensator to reduce the brightness of the backlight unit. to increase (B/L luminance↑) (S240).

As shown in FIG. 17 , when the data compensator of the timing controller performs the compensation operation, the voltages constituting the first gamma voltage GMA1 and the twelfth gamma voltage GMA12 are lower than before. However, in the drawings, the first gamma voltage GMA1 and the twelfth gamma voltage GMA12 are changed in the order of 16V and 0.2V to 12V and 4V as an example, but this is only an example and is not limited thereto.

In addition, when the dimming compensator of the timing controller performs the compensation operation, the brightness of the backlight unit is increased compared to the previous one. However, in the drawings, the luminance of the backlight unit is changed from 100% to 110% as an example, but this is only an example and is not limited thereto.

As described above, in the second embodiment of the present invention, a device and an algorithm can be implemented to set the driving method of the data driver and the backlight unit under the condition that the temperature of the device can be lowered in relation to the temperature, and to change it for each specific temperature range.

Therefore, in the second embodiment of the present invention, since the compensation operation is performed under the interworking of the timing controller, the data driver, and the backlight unit, it is possible to perform more sensitive and stable compensation even for a small temperature change. In addition, in the second embodiment of the present invention, since the compensation operation is performed under the interlocking of the device driving the liquid crystal panel, the display quality of the screen can be uniformly maintained even during the compensation operation.

<Third embodiment>

18 is a diagram illustrating a configuration of a power supply having a compensation circuit and a liquid crystal display using the same according to a third embodiment of the present invention, FIG. 19 is a schematic configuration diagram of a common voltage generator, and FIG. 20 is a common voltage generation It is an exemplary diagram of a detailed configuration of the part, FIG. 21 is a relationship diagram illustrating a relationship between a compensation step and a compensation method, and FIG. 22 is a relationship diagram illustrating a relationship between a temperature and a compensation method.

18 to 22 , in the liquid crystal display according to the third embodiment of the present invention, compensation circuits 192 and 195 are provided in the power supply unit 180 . The power supply unit 180 includes a temperature sensor unit 192 , a control signal output unit 195 , a driving voltage generation unit 183 , and a common voltage generation unit 185 . The driving voltage generator 183 outputs driving voltages such as the first power voltage VCC and the second power voltage GND.

The compensation circuits 192 and 195 are control signals CS corresponding to the temperature when the temperature of the power supply unit 180 increases due to the compensation operation of the common voltage generator for the power supply unit 180 to display a special pattern on the liquid crystal panel. ) is output.

The temperature sensor unit 192 includes, for example, a sensing transistor TS and a comparator operating based on the first power voltage VCC and the second power voltage GND supplied to the inside of the data driver 150 as shown in FIG. 8 . (CMP) and a resistor (Rs). The comparator CMP compares the voltage (or current) of the first terminal (+) to which the sensing transistor TS is connected and the voltage (or current) of the second terminal (-) to which the resistor Rs is connected, and The result value (voltage or current) is transmitted to the control signal output unit 195 . The resulting value (voltage or current) is defined as temperature information (TMP).

The control signal output unit 195 detects a temperature change of the data driver 150 based on the temperature information TMP transmitted from the temperature sensor unit 192, and generates a control signal CS in response to the temperature change. This is transferred to the common voltage generator 185 .

The common voltage generating unit 185 adjusts a gain for the common voltage to be supplied to the liquid crystal panel 160 based on the feedback common voltage VCOMFB fed back from the liquid crystal panel 160 , but receives the control signal output unit 195 from the control signal output unit 195 . The gain for the common voltage is varied based on the transferred control signal CS.

The common voltage generator 185 includes an amplifier AMP, a gain selector CMP, a first resistor R1, and a second resistor R2. The gain selector CMP is a circuit added as compensation circuits 192 and 195 are added to the power supply unit 180 and a compensation operation is performed.

The common voltage generator 185 responds to a change in the resistance of the second resistor R2 by the programmable variable common voltage PVCOM, the feedback common voltage VCOMFB, and the gain selector CMP. The gain is adjusted, and as a result, the compensation common voltage VCOMC outputted therethrough varies.

The amplifier unit AMP has a first terminal (+) connected to the variable common voltage line to which the variable common voltage PVCOM is transmitted, and a second terminal (-) to the feedback common voltage line to which the feedback common voltage VCOMFB is transmitted. and a third terminal (or an output terminal) is connected to the common voltage generator 185 . Also, the amplifying unit AMP has a bias terminal connected to the positive voltage line VS+ and the negative voltage line VS−.

One end of the first resistor R1 is connected to the feedback common voltage line and the other end is connected to the second terminal (-) of the amplifying unit AMP. The second resistor R2 has one end connected to the second terminal (-) of the amplifying unit AMP and the other end connected to the third terminal of the amplifying unit AMP.

The gain selection unit CMP is a gain selection signal Yes capable of changing the resistance value of the second resistor unit R2 based on the control signal CS and the reference voltage REF output from the control signal output unit 195 . , see No). Meanwhile, although the gain selector CMP is illustrated as a simple comparator, this is only an example and is not limited thereto.

For example, as shown in FIG. 20 , the common voltage generator 185 controls the switches included in the switch group SWG of the second resistor unit R2 based on the operation (OTP operation) of the gain selector CMP according to the temperature. The resistance value of the resistor group RG is changed through the on/off control. As a result, the amplification gain of the amplifying unit AMP is also varied. The resistor group RG is provided such that the resistance value increases or decreases toward the upper or lower direction of the drawing. The switch group SWG and the resistor group RG have a parallel connection structure.

Based on the above configuration and operation, when the temperature of the power supply unit 180 rises, the common voltage generating unit 185 adjusts the gain for the common voltage to be supplied to the liquid crystal panel 160, but as shown in FIG. The gain is lowered by I (I is an integer greater than or equal to 1) times or the second resistor R2 is changed to be used as a buffer with no gain. Meanwhile, the gain selector CMP may control on/off of the switch group SWG based on an internal memory, a lookup table, or a register. Accordingly, the common voltage generator 185 may increase or decrease the gain in units of steps.

In contrast, the conventional common voltage generator adjusts only the gain for the common voltage as part of a compensation operation in consideration of voltage drop when a special pattern is displayed on the liquid crystal panel, and increases the temperature of the device (temperature increase of the amplifier, etc.), etc. do not take into account As described above, if the gain is adjusted without considering the temperature of the device in the compensation operation, a load increase is induced, and consequently, the temperature of the power supply unit is inevitably increased continuously.

Therefore, the present invention compensates the common voltage in a manner of varying the gain for the common voltage (Gain 1 to Gain N) in response to the temperature change as shown in FIG. 22 and outputs the compensation common voltage VCOMC.

As described above, in the third embodiment of the present invention, the device and algorithm can be implemented to set the gain (or amplification ratio) of the common voltage under the condition that the temperature of the device can be lowered in relation to the temperature and to change it for each specific temperature range.

Therefore, in the third embodiment of the present invention, since the power supply unit controls its own output in response to a change in temperature, self-protection and compensation can be performed independently of other devices, which is easy to implement, and has a low-cost and high-efficiency effect. can get In addition, according to the third embodiment of the present invention, heat generation due to an increase in the load of the common voltage generated in the special pattern can be eliminated. In addition, the third embodiment of the present invention can prevent shutdown of a device such as a power supply unit (IC Shut Down) and a drop in the input voltage supplied to the power supply unit.

<Fourth embodiment>

23 is a diagram illustrating a configuration of a power supply unit having a compensation circuit and a liquid crystal display using the same according to a fourth embodiment of the present invention.

As shown in FIG. 23 , the liquid crystal display according to the fourth embodiment of the present invention includes a sensing circuit unit 190 including first and second temperature sensor units 192a and 192b and a control signal output unit 195 . is provided

The first and second temperature sensor units 192a and 192b respectively provided in the data driving unit 150 and the power supply unit 180 are provided to the control signal output unit 195 configured separately from the first and second temperature information TMP1. , to transmit TMP2). The control signal output unit 195 may be included in the timing control unit 130 .

The data driver 150 includes the inversion changer described in the first embodiment. Based on the first control signal CSa transmitted from the control signal output unit 195 , the inversion change unit performs compensation inversion in an optimal driving method capable of lowering the temperature of the data driving unit 150 and increasing the image quality, or The version method will be changed compared to the previous one.

Accordingly, when the first control signal CSa is output from the control signal output unit 195, the data driving unit 150 compensates for the first to Nth (N is an integer equal to or greater than 4) inversion method in response to the temperature change. It is implemented to perform a version or change the inversion method compared to the previous one.

The timing controller 130 includes the data compensator and the dimming compensator described in the second embodiment. The data compensator compensates the data signal in a form capable of lowering the temperature of the data driver 150 based on the second control signal CSb transmitted from the control signal output unit 195 and outputs the compensation data signal DATAC. . For example, the data compensator lowers the grayscale of the data signal in units of N (N is an integer greater than or equal to 1) grayscale based on the second control signal CSb.

In addition, the dimming compensator compensates the dimming value of the backlight unit 170 based on the second control signal CSb transmitted from the control signal output unit 195 and outputs the compensation dimming signal DIMC. For example, the dimming compensator increases the luminance in units of M (M is an integer greater than or equal to 1) nits based on the second control signal CSb and the compensation data signal DATAC.

Accordingly, when the second control signal CSb is output from the control signal output unit 195, the timing control unit 130 compensates the data signal DATA and the dimming signal DIM in response to the temperature change, and compensates the compensation data signal ( DATAC) and the compensation dimming signal DIMC.

The power supply unit 180 includes the common voltage generator described in the third embodiment. The common voltage generator varies the gain with respect to the common voltage based on the third control signal CSc transmitted from the control signal output unit 195 . For example, the common voltage generator lowers the gain for the common voltage by I (I is an integer greater than or equal to 1) times or is used as a buffer with no gain (the load is reduced, so the temperature rise factor of the device is eliminated).

Accordingly, when the third control signal CSc is output from the control signal output unit 195 , the power supply unit 180 compensates the common voltage by varying the gain for the common voltage in response to a temperature change and compensates the common voltage. (VCOMC) is output.

Meanwhile, the control signal output unit 195 receives the first to third control signals CSa to CSc generated therefrom in order to select an optimal driving method according to the temperature of the data driver 150 and the power supply unit 180 . It can optionally be printed out. For example, only one selected one of the first to third control signals CSa to CSc may be output, or two or three selected ones may be output.

As described above, the fourth embodiment of the present invention is one of the conditions under which the temperature of the device can be lowered in relation to temperature, (1) changing the inversion method, (2) changing the compensation data signal and the compensation dimming signal, and (3) changing the common voltage. Devices and algorithms can be implemented to utilize all of them. Therefore, in the fourth embodiment of the present invention, the compensation method can be changed by finding an optimal condition by using the combination of the first to third embodiments.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention can be changed to other specific forms by those skilled in the art to which the present invention pertains without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. In addition, the scope of the present invention is indicated by the claims to be described later rather than the above detailed description. In addition, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

110: image supply unit 130: timing control unit
140: gate driving unit 150: data driving unit
160: liquid crystal panel 170: backlight unit
180: power supply 190: sensing circuit unit
192: temperature sensor unit 195: control signal output unit
TMP: temperature information CS: control signal
158: inversion change unit 133: data compensation unit
135: dimming compensation unit 185: common voltage generation unit

Claims (10)

a liquid crystal panel for displaying an image;
a data driver supplying a data signal to the liquid crystal panel;
a timing controller for controlling the data driver; and
and a sensing circuit unit for sensing the temperature of the data driver and outputting a control signal based on the sensed temperature information,
The data driver changes the inversion method in response to the control signal, but performs a vertical two-dot inversion drive when its own temperature is lower than the reference temperature, and performs a column inversion drive when its own temperature is higher than the reference temperature,
The sensing circuit unit
a temperature sensor unit formed inside the data driving unit and outputting the temperature information;
And a control signal output unit for outputting a different control signal for each temperature range based on the temperature information,
The temperature sensor unit
a comparator having a first terminal connected to a first power supply voltage terminal;
a sensing transistor having a gate electrode and a first electrode commonly connected to the first terminal of the comparator and the first power supply voltage terminal, and a second electrode connected to a second power supply voltage terminal;
and a resistor having one end connected to the second terminal of the comparator and the first power supply voltage terminal and the other end connected to the second power supply voltage terminal. According to claim 1,
The data driver
In response to the control signal, one of the first polarity control signal provided from the timing control unit and the second polarity control signal set therein is selected and output as a third polarity control signal, and the third polarity control signal is output to its own digital analog A liquid crystal display device including an inversion change unit supplied to the conversion unit. delete delete a liquid crystal panel for displaying an image;
a backlight unit supplying light to the liquid crystal panel;
a data driver supplying a data signal to the liquid crystal panel;
a timing controller for controlling the data driver; and
and a sensing circuit unit for sensing the temperature of the data driver and outputting a control signal based on the sensed temperature information,
The timing controller outputs a signal for changing the luminance of the backlight unit along with the gray level of the data signal in response to the control signal, and outputs a compensation data signal for lowering the gray level of the data signal when the temperature of the data driver increases and output a compensation dimming signal to increase the brightness of the backlight unit,
The sensing circuit unit
a temperature sensor unit formed inside the data driving unit and outputting the temperature information;
And a control signal output unit for outputting a different control signal for each temperature range based on the temperature information,
The temperature sensor unit
a comparator having a first terminal connected to a first power supply voltage terminal;
a sensing transistor having a gate electrode and a first electrode commonly connected to the first terminal of the comparator and the first power supply voltage terminal, and a second electrode connected to a second power supply voltage terminal;
and a resistor having one end connected to the second terminal of the comparator and the first power supply voltage terminal and the other end connected to the second power supply voltage terminal. delete a liquid crystal panel for displaying an image;
a data driver supplying a data signal to the liquid crystal panel;
a power supply for supplying a common voltage to the liquid crystal panel;
a timing controller for controlling the data driver; and
and a sensing circuit unit for sensing the temperature of the power supply unit and outputting a control signal based on the sensed temperature information,
The power supply unit changes a gain for compensating and generating the common voltage in response to the control signal,
The power supply unit
an amplifier having a first terminal connected to a variable common voltage line to which a variable common voltage is transmitted and a second terminal connected to a feedback common voltage line through which a feedback common voltage is transmitted, and one end connected to the feedback common voltage line and the amplifying unit A first resistor unit having the other end connected to a second terminal, a second resistor unit having one end connected to the second terminal of the amplifying unit and the other end connected to the third terminal of the amplifying unit, based on the control signal and the internal reference voltage and a common voltage generator having a gain selector for outputting a gain select signal for changing a resistance value of the second resistor, wherein the second resistor comprises a switch group and a resistor group having a parallel connection structure, and the second resistor In response to the gain selection signal, the resistance value is varied as the on and off states of the switches of the switch group are changed,
The sensing circuit unit
a temperature sensor unit formed inside the power supply unit and outputting the temperature information;
And a control signal output unit for outputting a different control signal for each temperature range based on the temperature information,
The temperature sensor unit
a comparator having a first terminal connected to a first power supply voltage terminal;
a sensing transistor having a gate electrode and a first electrode commonly connected to the first terminal of the comparator and the first power supply voltage terminal, and a second electrode connected to a second power supply voltage terminal;
and a resistor having one end connected to the second terminal of the comparator and the first power supply voltage terminal and the other end connected to the second power supply voltage terminal. delete delete a liquid crystal panel for displaying an image;
a backlight unit supplying light to the liquid crystal panel;
a data driver supplying a data signal to the liquid crystal panel;
a power supply for supplying a common voltage to the liquid crystal panel;
a timing controller for controlling the data driver; and
A first temperature sensor unit formed in the data driving unit, a second temperature sensor unit formed in the power supply unit, and first to second temperature information output from the first and second temperature sensor units 3 comprising a sensing circuit unit having a control signal output unit for outputting at least one of the control signals,
The data driver changes the inversion method in response to the first control signal, but performs vertical 2-dot inversion driving when its own temperature is lower than the reference temperature, and performs column inversion driving when its own temperature is higher than the reference temperature do,
The timing controller outputs a signal for changing the luminance of the backlight unit along with the grayscale of the data signal in response to the second control signal,
The power supply unit changes a gain for compensating and generating the common voltage in response to the third control signal,
Each of the first and second temperature sensor units is
a comparator having a first terminal connected to a first power supply voltage terminal;
a sensing transistor having a gate electrode and a first electrode commonly connected to the first terminal of the comparator and the first power supply voltage terminal, and a second electrode connected to a second power supply voltage terminal;
and a resistor having one end connected to the second terminal of the comparator and the first power supply voltage terminal and the other end connected to the second power supply voltage terminal.

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