Gamma circuit and liquid crystal display device

Abstract

The invention relates to a gamma circuit and a liquid crystal display device, and relates to the technical field of display, the gamma circuit comprises a gray-scale chip, the gray-scale chip comprises a first end, a second end and a plurality of output ends, the first end is connected to a reference level, the second end is connected to the reference level, the plurality of output ends are configured to output a plurality of gray-scale voltages, and the plurality of gray-scale voltages are increased in sequence; the adjustment step of the gray-scale voltage = (reference level-reference level) / gray-scale chip debugging precision; therefore, by establishing the relationship between the gray scale voltage adjustment step and the gray scale chip debugging precision, adjusting the reference level and the reference level of each gray scale chip, and reducing the adjustment step of the gray scale voltage, the brightness compensation is more accurate and is more difficult to recognize by human eyes, thereby improving the stability of the panel brightness.

Description

Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to a gamma circuit and a liquid crystal display device. Background Art

[0002] The liquid crystal display comprises a liquid crystal display panel for displaying images and a liquid crystal display driving device for applying a driving signal to the liquid crystal display panel. The liquid crystal display panel comprises an array substrate and a color filter substrate arranged opposite to each other, and a liquid crystal layer filled in the gap between the array substrate and the color filter substrate.

[0003] Under normal temperature (25°C), the LCD device is powered on and left for about 30 minutes. When the liquid crystal temperature is stable, the desired grayscale-brightness characteristics can be achieved. However, in the early stage of the LCD device being powered on, the liquid crystal temperature is not yet stable, and in the later stage of the LCD device being powered on, the backlight source (or IC) generates heat, causing the liquid crystal temperature to rise, and the desired grayscale-brightness characteristics cannot be achieved, which easily leads to unstable display brightness. For LCD devices used for medical diagnosis, display abnormalities are life-threatening, so there is an urgent need to provide a gamma circuit and LCD device that can fine-tune the grayscale voltage according to temperature changes. Summary of the invention

[0004] In order to solve the above technical problems, the present disclosure provides a gamma circuit and a liquid crystal display device for reducing the adjustment step of the grayscale voltage, so that the brightness compensation is more accurate and less easily recognized by the human eye, thereby improving the brightness stability of the display panel.

[0005] In a first aspect, the present disclosure provides a gamma circuit, comprising: a grayscale chip, configured to output a grayscale voltage for display to a display panel, the grayscale chip comprising a first terminal, a second terminal and a plurality of output terminals, the first terminal being connected to a reference level, the second terminal being connected to a reference level, the plurality of output terminals being configured to output a plurality of grayscale voltages, the plurality of grayscale voltages being increased in sequence;

[0006] The grayscale voltage adjustment step = (reference level - reference level) / grayscale chip debugging accuracy, the grayscale chip debugging accuracy refers to the step that each grayscale can be adjusted.

[0007] The adjustment step of the grayscale voltage is less than or equal to 7mV.

[0008] In a second aspect, the present disclosure provides a liquid crystal display device, comprising: a display panel, a temperature sensor, a driving system, and a gamma circuit as described in the first aspect;

[0009] The temperature sensor is located in the display panel and is used to monitor the temperature of the liquid crystal display device in the display panel and transmit the temperature data to the driving system;

[0010] The driving system is used to control the gamma circuit to output a corresponding grayscale voltage in real time according to the temperature of the liquid crystal display device.

[0011] The technical solution provided by the embodiments of the present disclosure has the following advantages compared with the prior art: by establishing a relationship between the grayscale voltage adjustment step and the grayscale chip debugging accuracy, the number of grayscale chips is increased, the reference level and the benchmark level of each grayscale chip are adjusted, and the input level of the control end is adjusted based on the benchmark level of each grayscale chip, thereby reducing the adjustment step of each grayscale voltage, and realizing fine-tuning of the brightness of the display panel under the temperature change of the liquid crystal display device, so that the brightness compensation is more accurate and less easily recognized by the human eye, thereby improving the brightness stability of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0014] Figure 1 This is the trend diagram of liquid crystal driving voltage-transmittance;

[0015] Figure 2 It is a circuit diagram of a grayscale chip in the prior art;

[0016] Figure 3 is a graph showing the relationship between the grayscale voltage adjustment step and the display panel brightness change rate;

[0017] Figure 4 A schematic diagram of a gamma circuit according to an embodiment of the present disclosure;

[0018] Figure 5 A schematic diagram of a gamma circuit according to an embodiment of the present disclosure;

[0019] Figure 6 A schematic diagram of a gamma circuit according to an embodiment of the present disclosure;

[0020] Figure 7 This is a schematic diagram of the connection of the liquid crystal display device according to an embodiment of the present disclosure;

[0021] Figure 8 This is the grayscale-brightness curve with a gamma value of 2.2. DETAILED DESCRIPTION

[0022] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0023] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0024] Figure 1 This is a trend chart of the change of liquid crystal drive voltage-transmittance. There are many reasons for the change of brightness of liquid crystal display devices. The main reason is the heating of the backlight (and IC). As the temperature of the liquid crystal increases, the dielectric constant, refractive index and viscosity of the liquid crystal will decrease, resulting in a decrease in the transmittance of the liquid crystal. Please refer to Figure 1 , Figure 1 The solid line in the middle is the relationship curve between the liquid crystal driving voltage and the transmittance under ideal conditions, and the dotted line is the relationship curve between the liquid crystal driving voltage and the transmittance when the liquid crystal temperature increases. It can be seen from the figure that when the liquid crystal temperature increases, the same liquid crystal driving voltage is applied, and compared with the ideal situation, the transmittance of the liquid crystal decreases when the temperature increases.

[0025] In view of the above situation, it is necessary to adjust the grayscale voltage according to the temperature change to compensate for the loss of liquid crystal transmittance.

[0026] Figure 2 This is a circuit diagram of a grayscale chip in the prior art. Please refer to Figure 2 , the GND terminal of the grayscale chip 100' is grounded; the STATIC_Hi terminal of the grayscale chip 100' is used to access the reference level, and the reference level is determined by the maximum driving voltage of the liquid crystal; the grayscale chip 100' can output multiple grayscale voltages V out1 'To V outn '; The settable bit number of the grayscale chip 100' is 10 bits. The 10-bit grayscale chip is currently a commonly used grayscale chip. The debugging accuracy of the grayscale chip 100' is 1023. The maximum difference between the positive pressure and the negative pressure of the liquid crystal is usually above 11V, so the minimum adjustment step of the grayscale voltage 11V / 1023 is approximately equal to 10.7mV.

[0027] Figure 3 The relationship between the grayscale voltage adjustment step and the display panel brightness change rate is shown in Figure 2. According to the characteristics of the liquid crystal drive voltage and liquid crystal transmittance, the brightness change rate caused by the liquid crystal drive voltage is calculated. The results are shown in Figure 2. Figure 3 As shown. Figure 3It can be seen that curve I represents the brightness change rate when the grayscale voltage adjustment step is 15mV, curve II represents the brightness change rate when the grayscale voltage adjustment step is 10mV, and curve III represents the brightness change rate when the grayscale voltage adjustment step is 7mV. For curve II, when the grayscale voltage adjustment step is 10mV, in the range of 1V to 2.5V of the liquid crystal driving voltage, the brightness change rate exceeds 4%, while the brightness difference that can be recognized by the human eye is about 3%. That is to say, when the brightness change rate of the display panel is less than or equal to 3%, it is almost imperceptible to the human eye; combined with Figures 1 to 3 In the prior art, the relationship curve between the grayscale voltage adjustment step of 10.7mV and the brightness change rate is approximately curve II. Please refer to curve II. When the grayscale voltage adjustment step is 10mV, the brightness change rate of the display panel exceeds 3%, which will cause a visual experience of unstable brightness of the display panel. If you want the voltage change to be visually imperceptible, you need to set the grayscale voltage adjustment step to match the voltage change trend of curve III.

[0028] In response to the above problems, Figure 4 This is a schematic diagram of a gamma circuit according to an embodiment of the present disclosure. Please refer to Figures 1 to 4 In a first aspect, the present disclosure provides a gamma circuit 00, comprising: a grayscale chip 100, configured to output a grayscale voltage for display to a display panel, the grayscale chip 100 comprising a first terminal 101, a second terminal 102 and a plurality of output terminals 103, the first terminal 101 is connected to a reference level, the second terminal 102 is connected to a reference level, the plurality of output terminals 103 are configured to output a plurality of grayscale voltages, and the plurality of grayscale voltages are sequentially increased;

[0029] Grayscale voltage adjustment step = (reference level - reference level) / grayscale chip debugging accuracy. Grayscale chip debugging accuracy refers to the step that each grayscale can be adjusted.

[0030] The grayscale voltage adjustment step is less than or equal to 7mV.

[0031] Specifically, the gamma circuit 100 includes a grayscale chip 100, and the I2C interface of the grayscale chip 100 is used to receive a serial clock (SCL) signal, a serial data (SDA) signal, and a write enable signal (nWR), and provide the received signal and data to a timing controller, and the timing controller generates a timing control signal and data for generating a pixel grayscale voltage, and the data for generating the pixel grayscale voltage is temporarily stored in a memory, and the memory selection controller sends the data for generating the pixel grayscale voltage to a digital-to-analog converter (DAC), and the DAC converts the data signal into an analog signal, and the analog signal amplified and converted by the OP is used as the pixel grayscale voltage V out1 To V outnThe timing controller controls the timing of each OP to generate pixel grayscale voltage according to the timing control signal, and the liquid crystal molecule deflection reference voltage V com The module generates a reference voltage V for the deflection of liquid crystal molecules according to the timing controller. com_out The grayscale chip 100 includes a first terminal 101, the first terminal 101 is connected to a reference level, the grayscale chip 100 includes a second terminal 102, the second terminal 102 is connected to a reference level, the grayscale chip 100 includes a third terminal 103, the third terminal 103 outputs a plurality of grayscale voltages for display to the display panel, and the plurality of grayscale voltages increase in sequence from top to bottom or from bottom to top. In an optional embodiment provided in the present disclosure, the adjustment step of the grayscale voltage output by the third terminal 103 of the grayscale chip 100 satisfies the following conditions: the difference between the reference level connected to the second terminal 102 of the grayscale chip 100 and the reference level connected to the first terminal 101, divided by the debugging accuracy of the grayscale chip 100, is the adjustment step of the grayscale voltage; wherein the debugging accuracy of the grayscale chip 100 refers to the step that each grayscale can be adjusted, for example, If the number of settable bits of the grayscale chip 100 is 8 bits, the debugging accuracy of the grayscale chip 100 is 255, and accordingly, the adjustment step of the grayscale voltage = (reference level - reference level) / 255; if the number of settable bits of the grayscale chip 100 is 10 bits, the debugging accuracy of the grayscale chip 100 is 1023, and accordingly, the adjustment step of the grayscale voltage = (reference level - reference level) / 1023...I will not list them one by one here, it is only necessary to clarify that the debugging accuracy of the grayscale chip 100 is related to the number of bits of the grayscale chip 100. Further, in an optional embodiment provided in the present disclosure, the adjustment step of the grayscale voltage is less than or equal to 7mV; in this way, by establishing the relationship between the adjustment step of the grayscale voltage and the debugging accuracy of the grayscale chip, the adjustment step of the grayscale voltage can be further reduced. Please combine Figure 3 When the grayscale voltage adjustment step is less than or equal to 7mV, the brightness change of the display panel corresponding to the voltage change is similar to Curve III. At this time, the brightness change rate of the display panel can be controlled below 3%, which is almost imperceptible to the human eye, reducing the brightness instability of the display panel caused by the heating of the backlight (or chip).

[0032] Figure 5 This is a schematic diagram of a gamma circuit according to an embodiment of the present disclosure. Please refer to Figures 1 to 5 , the present disclosure provides a gamma circuit 00, the grayscale chip 100 also includes a control terminal 104, the control terminal 104 receives data for generating grayscale voltage from a driving system of a display panel;

[0033] The grayscale chip 100 includes a first grayscale chip 110 and a second grayscale chip 120. The reference level connected to the first end 111 of the first grayscale chip 110 is lower than the reference level connected to the first end 121 of the second grayscale chip 120; the reference level connected to the second end 112 of the first grayscale chip 110 is lower than the reference level connected to the second end 122 of the second grayscale chip 120;

[0034] The first grayscale chip 110 includes a plurality of first output terminals 113, and the plurality of first output terminals 113 are configured to output a plurality of first grayscale voltages, and the plurality of first grayscale voltages increase in sequence, and are respectively V out1 To V outn ;

[0035] The second grayscale chip 120 includes a plurality of second output terminals 123, which are configured to output a plurality of second grayscale voltages. The plurality of second grayscale voltages increase in sequence, and are respectively V out(n+1) To V out(n+m) ; V out(n+1) >V outn .

[0036] Specifically, the grayscale chip 100 in the gamma circuit 00 includes not only a first terminal 101, a second terminal 102, and an output terminal 103, but also a control terminal 104. The control terminal 104 is connected to the integrated circuit interface of the display panel driving system for receiving a data signal that generates a grayscale voltage. In an optional embodiment provided in the present disclosure, the grayscale chip 100 includes a first grayscale chip 110 and a second grayscale chip 120. The first grayscale chip 110 includes a first terminal 111, a second terminal 112, and a plurality of first output terminals 113. The first terminal 111 of the first grayscale chip 110 is connected to a reference level, and the second terminal 112 of the first grayscale chip 110 is connected to a reference level. The plurality of first output terminals 113 of the first grayscale chip 110 output a plurality of first grayscale voltages, which are V out1 To V outn , multiple first grayscale voltages increase in sequence; the second grayscale chip 120 includes a first terminal 121, a second terminal 122, and multiple second output terminals 123, the first terminal 121 of the second grayscale chip 120 is connected to the reference level, the second terminal 122 of the second grayscale chip 120 is connected to the reference level, and the multiple second output terminals 123 of the second grayscale chip 120 output multiple second grayscale voltages, which are V out(n+1) To V out(n+m), multiple second grayscale voltages increase in sequence; wherein, the reference level connected to the first end 121 of the second grayscale chip 120 is greater than the reference level connected to the first end 111 of the first grayscale chip 110, the reference level connected to the second end 122 of the second grayscale chip 120 is greater than the reference level connected to the second end 112 of the first grayscale chip 110, and the minimum grayscale voltage V output by the second output end 123 of the second grayscale chip 120 is out(n+1) is greater than the maximum grayscale voltage V outputted by the first output terminal 113 of the first grayscale chip 110 outn In this way, by setting the reference level connected to the first end 111 of the first grayscale chip 110 to be smaller than the reference level connected to the first end 121 of the second grayscale chip 120, and setting the reference level connected to the second end 112 of the first grayscale chip 110 to be smaller than the reference level connected to the second end 122 of the second grayscale chip 120, the cross-voltage of the first grayscale chip 110 and the second grayscale chip 120 can be reduced, which is beneficial to reducing the adjustment step of the grayscale voltage and improving the brightness stability of the display panel.

[0037] Please continue to refer to Figures 1 to 5 The present disclosure provides a gamma circuit 00, in which a control terminal 124 of a second grayscale chip 120 is connected to a first level converter 115, and the first level converter 115 is located at an integrated circuit interface of the second grayscale chip 120. The first level converter 115 is configured to adjust an input level of the control terminal 124 according to a reference level of the second grayscale chip 120.

[0038] Specifically, the control terminal 114 of the first grayscale chip 110 is connected to the integrated circuit interface for receiving a data signal for generating a grayscale voltage. The control terminal 124 of the second grayscale chip 120 is connected to the integrated circuit interface of the display panel driving system for receiving a data signal for generating a grayscale voltage. In an optional embodiment provided in the present disclosure, a first level converter 115 is further connected between the control terminal 124 of the second grayscale chip 120 and the integrated circuit interface. The first level converter 115 is used to adjust the input level of the control terminal 124 according to the reference level input to the first terminal 121 of the second grayscale chip 120. Since the reference level input to the first terminal 121 of the second grayscale chip 120 is greater than the reference level input to the first terminal 111 of the first grayscale chip 110, the control terminal 124 of the second grayscale chip 120 is connected to the integrated circuit interface of the display panel driving system. If the signal input of the control terminal 124 of the second grayscale chip 120 is based on the input level of the control terminal 114 of the first grayscale chip 110, then the input levels of the control terminal 124 of the second grayscale chip 120 are all lower than the reference level input at the first terminal 121 of the second grayscale chip 120, and the second grayscale chip 120 cannot be normally regulated. In this way, by adding a first level converter 115 between the control terminal 124 of the second grayscale chip 120 and the integrated circuit interface, the input level of the data signal of the control terminal 124 can be adjusted according to the reference level input at the first terminal 121 of the second grayscale chip 120, so as to facilitate the conversion of the level of the serial data and realize the normal regulation of the first grayscale chip 110 and the second grayscale chip 120.

[0039] Please continue to refer to Figures 1 to 5 The present disclosure provides a gamma circuit 00, wherein the reference level connected to the second end 122 of the second grayscale chip 120 is equal to a preset maximum driving voltage, and the reference level connected to the first end 121 of the second grayscale chip 120 is half of the preset maximum driving voltage; the preset maximum driving voltage is the maximum grayscale voltage provided to the display panel.

[0040] Specifically, when the gamma circuit 100 includes only the first grayscale chip 110 and the second grayscale chip 120, the reference level connected to the second end 122 of the second grayscale chip 120 is equal to the maximum grayscale voltage provided for the display panel, and the reference level connected to the first end 121 of the second grayscale chip 120 is half of the maximum grayscale voltage, that is, the difference between the reference level input to the second end 122 of the second grayscale chip 120 and the reference level input to the first end 121 of the second grayscale chip 120 is half of the maximum grayscale voltage of the display panel. For example, the maximum grayscale voltage of the display panel is 11V, the reference level input to the second end 122 of the second grayscale chip 120 is 11V, and the reference level input to the second end 122 of the second grayscale chip 120 is 11V. The reference level input to the first end 121 of the chip 120 is 5.5V, and the difference between the reference level input to the second end 122 of the second grayscale chip 120 and the reference level input to the first end 121 is 5.5V. That is to say, the cross-voltage of the second grayscale chip 120 is half of the maximum grayscale voltage of the display panel. In this way, the objective limitation that the grayscale voltage step is difficult to further reduce due to the number of bits of the grayscale chip 100 can be adjusted by changing the cross-voltage of the second grayscale chip 120. The reduction of the cross-voltage of the second grayscale chip 120 further reduces the step of the second grayscale voltage output by the second grayscale chip 120, thereby reducing the brightness difference of the display panel and improving the brightness stability of the display panel.

[0041] Please continue to refer to Figures 1 to 5 The present disclosure provides a gamma circuit 00, wherein a first end 111 of a first grayscale chip 110 is grounded, and a second end 112 of the first grayscale chip 110 is connected to a reference level that is half of a preset maximum driving voltage.

[0042] Specifically, in an optional embodiment provided by the present disclosure, the reference level connected to the second end 122 of the second grayscale chip 120 is the maximum grayscale voltage of the display panel 200, the reference level connected to the first end 121 of the second grayscale chip 120 is half of the maximum grayscale voltage of the display panel 200, and the input level of the control end 124 of the second grayscale chip 120 is based on the reference level connected to the first end 121 of the second grayscale chip 120; the reference level connected to the second end 112 of the first grayscale chip 110 is half of the preset maximum driving voltage, that is, the reference level connected to the second end 112 of the first grayscale chip 110 is half of the maximum grayscale voltage of the display panel, and the first end 111 of the first grayscale chip 110 is grounded, that is, the first grayscale chip The reference level connected to the first end 111 of 110 is 0V, that is, the voltage difference between the reference level input to the second end 122 of the second grayscale chip 120 and the reference level input to the first end 121 is half of the maximum grayscale voltage of the display panel, and the voltage difference between the reference level input to the second end 112 of the first grayscale chip 110 and the reference level input to the first end 111 is half of the maximum grayscale voltage of the display panel. In this way, the step of the first grayscale voltage output by the first grayscale chip 110 can be reduced by reducing the voltage difference between the reference voltage of the first grayscale chip 110 and the reference voltage to half of the maximum grayscale voltage of the display panel, thereby reducing the display brightness difference caused by the display panel adjusting the grayscale voltage according to temperature changes, thereby improving the brightness stability of the display panel.

[0043] Figure 6 This is a schematic diagram of a gamma circuit according to an embodiment of the present disclosure. Please refer to Figures 1 to 6 The present disclosure provides a gamma circuit 00, wherein the reference level connected to the second end 122 of the second grayscale chip 120 is less than the preset maximum driving voltage, and the grayscale chip 100 further includes at least one third grayscale chip 130, and the third grayscale chip 130 includes a plurality of third output terminals 133, and the plurality of third output terminals 133 are configured to output a plurality of third grayscale voltages, and the plurality of third grayscale voltages increase in sequence, and are V out(n+m+1) To V out(n+m+s) ; V out(n+m+1) >V out(n+m) , m, n, s are positive integers.

[0044] Specifically, in an optional embodiment provided by the present disclosure, when the reference level connected to the second end 122 of the second grayscale chip 120 is less than the maximum grayscale voltage of the display panel, that is, when the reference voltage connected to the second end 122 of the second grayscale chip 120 does not meet the liquid crystal AC drive, it is necessary to add another grayscale chip 100, the grayscale chip 100 includes a first grayscale chip 110, a second grayscale chip 120 and at least one third grayscale chip 130, the third grayscale chip 130 includes a first end 131, a second end 132, and a third output end 133, the first end 131 of the third grayscale chip 130 inputs a reference level, the second end 132 of the third grayscale chip 130 inputs a reference level, and the third output end 133 of the third grayscale chip 130 outputs V out(n+m+1) To V out(n+m+s) A third grayscale voltage is provided, and the plurality of third grayscale voltages increase sequentially, and the minimum grayscale voltage outputted by the third output terminal 133 of the third grayscale chip 130 is greater than the maximum grayscale voltage outputted by the second output terminal 123 of the second grayscale chip 120, and m, n, and s are positive integers. In this way, when the reference voltage inputted by the second grayscale chip 120 does not meet the maximum grayscale voltage of the liquid crystal AC drive, by increasing the number of grayscale chips 100, the voltage difference between the reference voltage and the reference voltage of a single grayscale chip 100 can be reduced while meeting the liquid crystal AC drive, thereby reducing the adjustment step of the grayscale voltage and improving the brightness stability of the display panel.

[0045] It should be noted that the present disclosure does not specifically limit the number of the output terminals 103 of the grayscale chip 100 , and can be set according to actual needs, as long as the grayscale voltages output by the output terminals 103 of the grayscale chip 100 increase in sequence.

[0046] Please continue to refer to Figures 1 to 6 , the present disclosure provides a gamma circuit 00, the third grayscale chip 130 also includes a control terminal 134, the control terminal 134 is configured to receive data for generating a grayscale voltage from a driving system of a display panel; the control terminal 134 of the third grayscale chip 130 is connected to a second level converter 125, the second level converter 125 is located at an integrated circuit interface of the third grayscale chip 130, and the second level converter 125 is configured to adjust the input level of the control terminal 134 according to a reference level input from a first terminal 131 of the third grayscale chip 130; the control terminal 124 of the second grayscale chip 120 is connected to a first level converter 115, the first level converter 115 is located at an integrated circuit interface of the second grayscale chip 120, and the first level converter 115 is configured to adjust the input level of the control terminal 124 according to the reference level of the first terminal 121 of the second grayscale chip 120.

[0047] Specifically, when the reference voltage input to the second terminal 122 of the second grayscale chip 120 is less than the maximum grayscale voltage of the display panel 200, the grayscale chip 100 further includes at least one third grayscale chip 130. In addition to the first terminal 131, the second terminal 132, and the third output terminal 133, the third grayscale chip 130 further includes a control terminal 134. The control terminal 134 of the third grayscale chip 130 is connected to the integrated circuit interface of the display panel driving system for receiving data for generating a grayscale voltage. In an optional embodiment provided in the present disclosure, a second level converter 125 is further connected between the control terminal 134 of the third grayscale chip 130 and the integrated circuit interface of the display panel driving system. The second level converter 125 can adjust the input level of the control terminal 134 of the third grayscale chip 130 according to the reference level input to the first terminal 131 of the third grayscale chip 130. A first level converter 115 is also connected between the control terminal 124 of the display panel 20 and the integrated circuit interface of the display panel driving system. The first level converter 115 can adjust the input level of the control terminal 124 of the second grayscale chip 120 according to the reference level input by the first terminal 121 of the second grayscale chip 120, that is, the input level of the control terminal 124 of the second grayscale chip 120 is greater than the input level of the control terminal 114 of the first grayscale chip 110, and the input level of the control terminal 134 of the third grayscale chip 130 is greater than the input level of the control terminal 124 of the second grayscale chip 120. In this way, on the basis of reducing the voltage difference between the reference level and the reference level of each grayscale chip 100, the input level of the control terminal 104 of each grayscale chip 100 can be adjusted according to the reference level input by the first terminal 101 of each grayscale chip 100 through the level converter, so as to achieve normal regulation of each grayscale chip 100.

[0048] Please continue to refer to Figures 1 to 6 The present disclosure provides a gamma circuit 00, wherein the reference level connected to the second end 132 of the third grayscale chip 130 is equal to a preset maximum driving voltage, and the preset maximum driving voltage is the maximum grayscale voltage provided to the display panel; the reference level connected to the second end 122 of the second grayscale chip 120 is less than the reference level connected to the second end 132 of the third grayscale chip 130, and the reference level connected to the second end 112 of the first grayscale chip 110 is less than the reference level connected to the second end 122 of the second grayscale chip 120; the reference level connected to the first end 131 of the third grayscale chip 130 is greater than the reference level connected to the first end 121 of the second grayscale chip 120, and the reference level connected to the first end 121 of the second grayscale chip 120 is greater than the reference level connected to the first end 111 of the first grayscale chip 110, and the first end 111 of the first grayscale chip 110 is grounded.

[0049] Specifically, in an optional embodiment provided by the present disclosure, when there is only one third grayscale chip 130, the reference level connected to the second end 132 of the third grayscale chip 130 is the maximum grayscale voltage of the display panel 200, the reference level connected to the first end 131 of the third grayscale chip 130 is less than the reference level connected to the second end 132 of the third grayscale chip 130, and the input level of the control end 134 of the third grayscale chip 130 is adjusted according to the reference level of the first end 131 of the third grayscale chip 130; the reference level connected to the second end 122 of the second grayscale chip 120 is less than the reference level connected to the second end 132 of the third grayscale chip 130, the reference level connected to the first end 121 of the second grayscale chip 120 is less than the reference level connected to the first end 131 of the third grayscale chip 130, and the second grayscale chip 120 control end 134 is adjusted according to the reference level of the first end 131 of the third grayscale chip 130. The input level of the control terminal 124 is adjusted according to the reference level of the first terminal 121 of the second grayscale chip 120; the reference level connected to the second terminal 112 of the first grayscale chip 110 is less than the reference level connected to the second terminal 122 of the second grayscale chip 120, the reference level connected to the first terminal 111 of the first grayscale chip 110 is less than the reference level connected to the first terminal 121 of the second grayscale chip 120, and the first terminal 111 of the first grayscale chip 110 is grounded. In this way, the maximum grayscale voltage of the display panel is distributed into the cross-voltage of multiple grayscale chips 100 to reduce the difference between the reference voltage and the reference voltage of each grayscale chip 100. In the case where the objectively existing debugging accuracy of the grayscale chip 100 cannot be changed, the cross-voltage on the grayscale chip 100 is reduced to reduce the grayscale voltage adjustment step, thereby improving the brightness stability of the display panel.

[0050] For example, when the maximum driving voltage of the display panel is 12V, the reference voltage connected to the second end 132 of the third grayscale chip 130 is 12V, the reference voltage connected to the first end 131 of the third grayscale chip 130 is 8V, and the difference between the reference voltage and the reference voltage of the third grayscale chip 130 is 4V, that is, the cross voltage on the third grayscale chip 130 is 4V, the reference voltage connected to the second end 122 of the second grayscale chip 120 is 8V, the reference voltage connected to the first end 121 of the second grayscale chip 120 is 4V, and the difference between the reference voltage and the reference voltage of the second grayscale chip 120 is 4V, that is, the cross voltage on the second grayscale chip 120 is 4V, the reference voltage connected to the second end 112 of the first grayscale chip 110 is 4V, the first end 111 of the first grayscale chip 110 is grounded, and the difference between the reference voltage and the reference voltage of the first grayscale chip 110 is 4V, that is, That is, the cross voltage on the first grayscale chip 110 is 4V. Assuming that the first grayscale chip 110, the second grayscale chip 120 and the third grayscale chip 130 can set the bit number to 10bit, that is, the debugging accuracy of the grayscale chip 100 is 1023, then the adjustment step of the grayscale voltage outputted from the output terminal 103 of the first grayscale chip 110, the second grayscale chip 120 and the third grayscale chip 130 is 4V / 1023, that is, the adjustment step of the grayscale voltage is about 3.9mV, compared with the case where only one grayscale chip 100 is used, the adjustment step of the grayscale voltage is 12V / 1023, which is about 11.7mV. It can be seen that the gamma circuit 00 provided in the embodiment of the present disclosure can further reduce the adjustment step of the grayscale voltage, can fine-tune the grayscale voltage under temperature changes, reduce the brightness change rate of the display panel, and improve the brightness stability of the display panel.

[0051] It should be noted that the above only takes the maximum grayscale voltage of 12V of the display panel as an example, which does not represent the maximum grayscale voltage of the display panel during actual operation; the above only takes the equal cross-voltage of the three grayscale chips 100 as an example, which does not represent the cross-voltage distribution of the grayscale chips 100 during actual operation. Specifically, the cross-voltages between the first grayscale chip 110, the second grayscale chip 120, and the third grayscale chip 130 may be equal or unequal, and the present disclosure does not make specific limitations on this, which shall be subject to actual needs; the above only takes the grayscale chip 100 as an example in which the number of bits that can be set to 10 bits, which does not represent the actual number of bits that can be set to the grayscale chip 100. For example, the number of bits that can be set to the grayscale chip 100 can also be 8 bits... and so on, which are not listed one by one here, and can be set according to actual needs.

[0052] Figure 7 This is a schematic diagram of the connection of the liquid crystal display device according to the embodiment of the present disclosure. Please refer to Figures 1 to 7In a second aspect, the present disclosure provides a liquid crystal display device 300, comprising: a display panel 200, a temperature sensor 201, a driving system 10, and a gamma circuit 00 as described above; the temperature sensor 201 is located in the display panel 200, and is used to monitor the temperature of the liquid crystal display device 300 and transmit the temperature data to the driving system 10; the driving system 10 is used to control the gamma circuit 00 to output a corresponding grayscale voltage in real time according to the temperature of the liquid crystal display device.

[0053] Specifically, in an optional embodiment provided by the present disclosure, a liquid crystal display device 300 includes a display panel 200, the display panel 200 includes a backlight source, the backlight source is used to provide a light source for a liquid crystal layer in the display panel 200, the liquid crystal display device 300 includes a driving system 10, the driving system 10 includes at least one main control chip 01, the main control chip 01 has a storage function, the compensation curve is pre-stored in the main control chip 01, and the gamma circuit 00 is controlled by the main control chip 01; the liquid crystal display device 300 also includes a temperature sensor 201, the temperature sensor 201 is located in the display panel 200, and the temperature sensor 201 is also electrically connected to the main control chip 01 in the driving system 10. The temperature sensor 201 is used to monitor the temperature of the liquid crystal display device 300, that is, it can be achieved by monitoring the temperature of the backlight source, or by monitoring the temperature of the display panel 200 (such as by setting the temperature sensor 201 inside the display panel 200, etc.), and the monitored temperature data is transmitted to the main control chip 01. The main control chip 01 controls the gamma circuit 00 as described above to adjust the grayscale voltage output to the display panel 200 in real time according to the received temperature data, drives the liquid crystal layer to deflect, and adjusts the display brightness of the display panel 200. The driving system 10 is used to control the gamma circuit 00 to output the corresponding grayscale voltage according to the monitored temperature, so as to drive the liquid crystal layer to deflect. In this way, by setting the gamma circuit 00 whose grayscale voltage adjustment step can be fine-tuned, and the temperature sensor 201 set in the display panel 200 for monitoring the temperature, the grayscale voltage output to the display panel 200 can be adjusted in real time according to the temperature of the liquid crystal display device 300. The smaller the adjustment step of the grayscale voltage, the more precise the adjustment range of the grayscale voltage, which can make the brightness change of the display panel 200 lower than the recognition rate of the human eye, thereby improving the brightness stability of the display panel 200.

[0054] Figure 8 For the grayscale-brightness curve with a gamma value of 2.2, please refer to Figures 1 to 8 In a liquid crystal display device 300 provided by the present disclosure, a driving system 10 pre-stores a data set of temperature-grayscale node voltage, and the data set of temperature-grayscale node voltage includes grayscale voltages corresponding to different temperatures when the gamma value is 2.2.

[0055] Specifically, in an optional embodiment provided by the present disclosure, the driving system 10 of the liquid crystal display device 300 pre-stores a grayscale voltage data set corresponding to different temperatures when the gamma value is 2.2. Figure 8 The brightness response curve of most display devices is closest to the brightness perception curve of the human eye when the gamma value is 2.2. The driving system 10 of the liquid crystal display device 300 pre-stores the grayscale-brightness curve diagram when the gamma value is 2.2, and needs to collect the temperature-grayscale node voltage data set in advance to confirm the grayscale voltage change corresponding to the temperature change under the condition that the gamma value remains at 2.2. After the temperature sensor 201 detects the temperature change, it feeds back to the main control chip 01. The main control chip 01 outputs the grayscale voltage according to the temperature change based on the data in the temperature-grayscale node voltage data set to keep the display brightness of the liquid crystal display device 300 stable.

[0056] The temperature-grayscale node voltage data set needs to be collected separately for each liquid crystal display device 300. The main control chip 01 in the driving system 10 will pre-collect the node voltage versions that the gamma circuit 00 should output when the gamma standard value is 2.2 at different temperatures. When the main control chip 01 recognizes that the liquid crystal display device 300 rises or falls to these temperatures, it will control the gamma circuit 00 to change its output grayscale voltage so that the display brightness remains basically unchanged and the gamma curve is fixed near the standard value of 2.2. In this way, after receiving the real-time monitored temperature of the liquid crystal display device 300, the driving system 10 can control the gamma circuit 00 to output the corresponding grayscale voltage according to the pre-stored temperature-grayscale node voltage data set, so that the display brightness of the display panel 200 is as close as possible to the brightness perception of the human eye.

[0057] In summary, the present disclosure provides a gamma circuit and a liquid crystal display device. By establishing a relationship between the grayscale voltage adjustment step and the grayscale chip debugging accuracy, the grayscale voltage adjustment step is further reduced, thereby controlling the brightness difference of the display panel to be less than 3%, and reducing the brightness instability of the display panel caused by the heating of the backlight (or chip); by setting the reference level connected to the first end of the first grayscale chip to be smaller than the reference level connected to the first end of the second grayscale chip, and setting the reference level connected to the second end of the first grayscale chip to be smaller than the reference level connected to the second end of the second grayscale chip, the cross voltage of the first grayscale chip and the second grayscale chip can be reduced, which is conducive to reducing the grayscale voltage adjustment step; by adding a first level converter between the control end of the second grayscale chip and the integrated circuit interface, the input level of the control end data signal can be adjusted according to the reference level input to the first end of the second grayscale chip, so as to facilitate the normal regulation of the second grayscale chip; when the reference voltage input to the second grayscale chip does not meet the maximum grayscale voltage of the liquid crystal AC drive, by increasing the number of grayscale chips, while meeting the liquid crystal AC drive, the difference between the reference voltage and the reference voltage of a single grayscale chip can be reduced. The voltage difference is reduced, thereby reducing the grayscale voltage adjustment step and improving the brightness stability of the display panel; through the level converter, the input level of each grayscale chip control end is adjusted according to the reference level input at the first end of each grayscale chip to achieve normal regulation of each grayscale chip; by distributing the maximum grayscale voltage of the display panel into the cross-voltage of multiple grayscale chips to reduce the difference between the reference voltage and the reference voltage of each grayscale chip, when the objective grayscale chip debugging accuracy cannot be changed, by reducing the cross-voltage on the grayscale chip, the grayscale voltage adjustment step is increased, thereby improving the brightness stability of the display panel. Qualitative; by setting a gamma circuit with fine-tunable grayscale voltage adjustment steps and a temperature sensor set in the display panel, the grayscale voltage output to the display panel can be adjusted in real time according to the temperature monitored by the liquid crystal display device. The grayscale voltage adjustment step is small, which can make the adjustment range of the grayscale voltage more precise, thereby making the brightness change of the display panel lower than the recognition rate of the human eye, so as to improve the brightness stability of the display panel; according to the pre-stored temperature-grayscale node voltage data set, the gamma circuit is controlled to output the corresponding grayscale voltage, so that the display brightness of the display panel is as close as possible to the brightness perception of the human eye.

[0058] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0059] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gamma circuit, characterized in that: include: A grayscale chip is configured to output a grayscale voltage for display to a display panel, the grayscale chip comprises a first terminal, a second terminal and a plurality of output terminals, the first terminal is connected to a reference level, the second terminal is connected to a reference level, the plurality of output terminals are configured to output a plurality of grayscale voltages, and the plurality of grayscale voltages are increased in sequence; The grayscale voltage adjustment step = (reference level - reference level) / grayscale chip debugging accuracy, the grayscale chip debugging accuracy refers to the step that each grayscale can be adjusted. The adjustment step of the grayscale voltage is less than or equal to 7mV.

2. The gamma circuit according to claim 1, wherein: The grayscale chip further includes a control terminal, wherein the control terminal receives data for generating grayscale voltage from a driving system of the display panel; The grayscale chip comprises a first grayscale chip and a second grayscale chip, wherein a reference level connected to a first end of the first grayscale chip is lower than a reference level connected to a first end of the second grayscale chip; The reference level connected to the second end of the first grayscale chip is lower than the reference level connected to the second end of the second grayscale chip; The first grayscale chip includes a plurality of first output terminals, and the plurality of first output terminals are configured to output a plurality of first grayscale voltages, and the plurality of first grayscale voltages increase in sequence, and are respectively V out1 To V outn ; The second grayscale chip includes a plurality of second output terminals, which are configured to output a plurality of second grayscale voltages, and the plurality of second grayscale voltages increase in sequence, and are respectively V out(n+1) To V out(n+m) ; V out(n+1) >V outn .

3. The gamma circuit according to claim 2, characterized in that: The control end of the second grayscale chip is connected to a first level converter, which is located at the integrated circuit interface of the second grayscale chip and is configured to adjust the input level of the control end according to the reference level of the second grayscale chip.

4. The gamma circuit according to claim 2, wherein: The reference level connected to the second end of the second grayscale chip is equal to the preset maximum driving voltage, and the reference level connected to the first end of the second grayscale chip is half of the preset maximum driving voltage; The preset maximum driving voltage is a maximum grayscale voltage provided to the display panel.

5. The gamma circuit according to claim 4, characterized in that: A first terminal of the first gray scale chip is grounded, and a second terminal of the first gray scale chip is connected to a reference level that is half of the preset maximum driving voltage.

6. The gamma circuit according to claim 2, characterized in that: The reference level connected to the second end of the second grayscale chip is less than the preset maximum driving voltage, and the grayscale chip further includes at least one third grayscale chip. The third grayscale chip includes a plurality of third output terminals, which are configured to output a plurality of third grayscale voltages, and the plurality of third grayscale voltages increase in sequence, and are respectively V out(n+m+1) To V out(n+m+s) ; V out(n+m+1) >V out(n+m) , m, n, s are positive integers.

7. The gamma circuit according to claim 6, wherein: The third grayscale chip further includes a control terminal, the control terminal being used to receive data for generating grayscale voltage from a driving system of the display panel; The control end of the third grayscale chip is connected to a second level converter, the second level converter is located at the integrated circuit interface of the third grayscale chip, and the second level converter is configured to adjust the input level of the control end according to the reference level of the third grayscale chip; The control end of the second grayscale chip is connected to a first level converter, which is located at the integrated circuit interface of the second grayscale chip and is configured to adjust the input level of the control end according to the reference level of the second grayscale chip.

8. The gamma circuit according to claim 7, characterized in that: The reference level connected to the second end of the third grayscale chip is equal to a preset maximum driving voltage, and the preset maximum driving voltage is a maximum grayscale voltage provided to the display panel; The reference level connected to the second end of the second grayscale chip is smaller than the reference level connected to the second end of the third grayscale chip, and the reference level connected to the second end of the first grayscale chip is smaller than the reference level connected to the second end of the second grayscale chip; The reference level connected to the first end of the third grayscale chip is greater than the reference level connected to the first end of the second grayscale chip, the reference level connected to the first end of the second grayscale chip is greater than the reference level connected to the first end of the first grayscale chip, and the first end of the first grayscale chip is grounded.

9. A liquid crystal display device, characterized in that: include: A display panel, a temperature sensor, a driving system, and a gamma circuit as claimed in any one of claims 1 to 8; The temperature sensor is located in the display panel and is used to monitor the temperature of the liquid crystal display device and transmit the temperature data to the driving system; The driving system is used to control the gamma circuit to output a corresponding grayscale voltage in real time according to the temperature of the liquid crystal display device.

10. The liquid crystal display device according to claim 9, wherein: The driving system pre-stores a data set of temperature-grayscale node voltage, and the data set of temperature-grayscale node voltage includes grayscale voltages corresponding to different temperatures when the gamma value is 2.2.

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