CN101311782B - Gray-scale voltage generation circuit and its operation method - Google Patents

Abstract

A gray scale voltage generating circuit receives a pixel data, generates a first set of gray scale voltages according to a first set of reference voltages in a first time period to enable a display to display a plurality of different gray scales according to the pixel data, and generates a second set of gray scale voltages according to a second set of reference voltages in a second time period to enable the display to display a common gray scale, wherein the first set of reference voltages is different from the second set of reference voltages.

Description

Gray-scale voltage generation circuit and its operation method

technical field

The invention relates to a gray scale (Gray Scale) voltage generation circuit, in particular to a gray scale voltage generation circuit suitable for flat panel displays.

Background technique

In recent years, many flat panel display (Flat Panel Display) technologies have been developed one after another. Among them, liquid crystal display (LCD) has the advantages of high image quality, small size, light weight, low voltage drive, low power consumption and wide application range. Therefore, it is widely used in consumer electronics or computer products such as medium and small portable TVs, mobile phones, video recorders, notebook computers, desktop monitors, and projection TVs, and has gradually replaced cathode ray tubes. (Cathode Radiation Tube; CRT) has become the mainstream of future displays, especially Thin Film Transistor (Thin Film Transistor; TFT) liquid crystal displays, which almost occupy most of the market due to their high display quality and low power consumption.

TFT-LCDs apply an appropriate grayscale voltage to the pixels on the panel to change the angle of the liquid crystal molecules of the pixels, thereby changing the light transmittance of the panel to achieve the grayscale to be displayed. However, because the image display method of the liquid crystal display is a hold-type (Hold-type) display method, which is different from the pulse-type (Impulse-type) display method of the traditional cathode ray tube display, therefore, when using the hold-type display method When a dynamic image is displayed in an image mode, a blurring phenomenon will occur to the human visual system. The currently known solution is to switch the backlight module on and off, or input a black picture signal from the system side to insert a black picture to solve the above problems. However, constantly switching the backlight module on and off will cause the backlight module to consume a lot of power, and if the signal for black screen is sent from the system side, an additional control signal is required, which will increase the circuit design of the system side. the complexity.

In addition, at the moment when the liquid crystal display is turned on (TurnOn), the correct data signal at this time, such as a low voltage differential signal (Low Voltage Differential Signal; LVDS), has not yet been input to the data driver circuit (Data Driver), but at this time the data Due to the previous display or other factors, the driving circuit will have a residual data potential inside, which is called the initial state (Initial State), and immediately output this residual data potential. Moreover, different data drivers (Driving IC) will Different signals are output according to its different initial states. Although the light tube has not been turned on at this time, band-like noise can still be faintly seen on the screen.

Contents of the invention

Therefore, the object of the present invention is to provide a grayscale voltage generating circuit that can output black images without switching the backlight module on and off.

Another object of the present invention is to provide a gray-scale voltage generating circuit. The switches in the gray-scale voltage generating circuit are arranged in the data driver, and by controlling these switches, the display can output a black screen, so as to avoid the system power supply. Banding noise produced on a monitor screen.

Another object of the present invention is to provide a gray-scale voltage generating circuit. The switches provided in the gray-scale voltage generating circuit can be directly formed by the data driver process, so the cost of parts can be saved.

Another object of the present invention is to provide a grayscale voltage generating circuit, the switch is directly arranged in the data driver, so it is easier to achieve high frequency operation.

According to the above object of the present invention, a device is proposed, which at least includes a grayscale voltage generating circuit, which can receive a pixel data, and can generate a first set of reference voltages according to a first set of reference voltages in a first time period. grayscale voltages, so that a display can display a plurality of different grayscale levels according to the pixel data, and a second set of grayscale voltages can be generated according to a second set of reference voltages in a second time period, so as to The display is made to display a common gray scale, wherein the first set of reference voltages is different from the second set of reference voltages.

According to an embodiment of the present invention, the above-mentioned common grayscale includes at least one black frame.

According to another object of the present invention, a gray scale voltage generating circuit is provided in a data driver. The above-mentioned gray scale voltage generation circuit includes at least a first digital/analog converter and a first switch circuit. The first digital/analog converter is used to output a first set of grayscale voltages. The first switch circuit at least includes a first switch, a second switch and a first input terminal. The first switch is electrically connected to the first digital/analog converter, the second switch is electrically connected to the first input terminal, and the second switch and the first switch are in reverse phase. The first input terminal can input a first reference voltage.

In a first time period, the first switch is turned on and the second switch is not turned on, then the first digital/analog converter outputs a first set of grayscale voltages, so that a display can display multiple different grayscales, In a second time period, the first switch is not turned on and the second switch is turned on, so that the first reference voltage is output, so that the display can display a common gray scale.

According to an embodiment of the present invention, at least a selector electrically connected to the first input terminal is included to select the first reference voltage from a plurality of reference voltage sources. According to an embodiment of the present invention, at least one timing control circuit is included to output a control signal for controlling the above-mentioned switch.

According to another object of the present invention, a grayscale voltage generating circuit is proposed, which at least includes a first voltage terminal, a second voltage terminal, multiple voltage dividing circuits, multiple switches, a first internal resistance string and a first Two internal resistor strings. The first voltage terminal is used for inputting a first reference voltage, and the second voltage terminal is used for inputting a second reference voltage. Multiple voltage dividing circuits are electrically connected between the first voltage terminal and the second voltage terminal for generating multiple divided voltages. A plurality of switches, wherein one end of each switch is respectively electrically connected with a part of the voltage dividing circuit. The first internal resistor string is electrically connected to the maximum of these divided voltages and the other end of some of the switches. The first internal resistor string can further divide a part of these divided voltages into a first group of gray scale voltages for output. The second internal resistor string is electrically connected to the smallest of these divided voltages and the other ends of the remaining switches. The second internal resistor string can further divide the remaining divided voltages into a second group of gray scale voltages for output.

During a first time period, these switches are turned on, and the gray-scale voltage generating circuit outputs a first set of gray-scale voltages and a second set of gray-scale voltages through the first internal resistor string and the second internal resistor string, so that a display Displays multiple different shades of gray. In a second time period, these switches are not turned on, and the gray scale voltage generating circuit outputs the maximum of these divided voltages and the minimum of these divided voltages through the first internal resistor string and the second internal resistor string, so that The display shows a common grayscale.

According to an embodiment of the present invention, at least a timing control circuit is included to output a control signal for controlling the switches. The above switch is an N-type metal oxide semiconductor transistor (NMOS) or a P-type metal oxide semiconductor transistor (PMOS), and the display is a twisted nematic liquid crystal display.

According to another object of the present invention, a gray scale voltage generating circuit is proposed, which at least includes a first voltage terminal, a second voltage terminal, multiple voltage dividing circuits, multiple first switches, a first internal resistance string, A second internal resistance string, a second switch, a third switch, a third voltage terminal and a fourth voltage terminal. The first voltage terminal is used for inputting a first reference voltage, and the second voltage terminal is used for inputting a second reference voltage. Multiple voltage dividing circuits are electrically connected between the first voltage terminal and the second voltage terminal for generating multiple divided voltages. A plurality of first switches, wherein one end of each first switch is respectively electrically connected to the first voltage end and each of these voltage dividing circuits. The first internal resistor string is electrically connected to the other end of the first part of the first switches, and the first internal resistor string can divide part of these divided voltages into a first group of gray scale voltages for output. The second internal resistor string is electrically connected to the other ends of the remaining first switches, and the second internal resistor string can divide the remaining voltages into a second group of gray scale voltages for output. The second switch is electrically connected between one of the first switches and the first internal resistance string, and the second switch is in antiphase with the first switches. The third switch is electrically connected between another one of the first switches and the second internal resistance string, and the third switch is in antiphase with the first switches. The third voltage end is electrically connected to the second switch, and the third voltage end is used for inputting a third reference voltage. The fourth voltage terminal is electrically connected to the third switch, and the fourth voltage terminal is used for inputting a fourth reference voltage.

In a first time period, the first switches are turned on, the second switch and the third switch are not turned on, and the gray scale voltage generation circuit outputs the first group of gray scales through the first internal resistor string and the second internal resistor string The voltage and the second group of gray scale voltages enable a display to display multiple different gray scales. In a second time period, the first switches are not turned on, the second switch and the third switch are turned on, and the gray scale voltage generation circuit outputs the third reference voltage through the first internal resistor string and the second internal resistor string and the fourth reference voltage to make the display display a common gray scale.

According to an embodiment of the present invention, when the display is a vertical alignment liquid crystal display, the third reference voltage and the fourth reference voltage are equal to the V _COM voltage. When the display is a twisted nematic liquid crystal display, the third reference voltage is equal to the maximum of the first group of gray-scale voltages, and the fourth reference voltage is equal to the minimum of the second group of gray-scale voltages. According to an embodiment of the present invention, it further includes at least one control circuit capable of outputting a control signal for controlling the switches.

According to yet another object of the present invention, a method for operating a grayscale voltage generating circuit is proposed, at least including: controlling multiple reference voltages to generate multiple grayscale voltages, so as to control the grayscale displayed by multiple pixels of a display . The above step of controlling these reference voltages at least includes: in a first time period, setting these reference voltages to different values, so that these pixels display different gray scales according to the pixel data; and in a second time period In the present invention, these reference voltages are set to one or more values, so that these pixels display a common gray scale, and the common gray scale has nothing to do with the pixel data.

According to an embodiment of the present invention, the step of controlling the reference voltages at least includes controlling a plurality of switches to determine the set values of the reference voltages.

Description of drawings

In order to make the above and other purposes, features, and advantages of the present invention more clearly understood, a preferred embodiment is specifically cited, and detailed descriptions are as follows in conjunction with the accompanying drawings:

Fig. 1 shows a schematic diagram of a grayscale voltage generating circuit according to a first embodiment of the present invention.

Fig. 2 shows a schematic diagram of a grayscale voltage generating circuit according to a second embodiment of the present invention.

FIG. 3 shows a schematic diagram of a grayscale voltage generation circuit according to a third embodiment of the present invention.

Fig. 4 shows a schematic diagram of a grayscale voltage generating circuit according to a fourth embodiment of the present invention.

FIG. 5 shows a schematic diagram of timing control for generating a black picture by the gray scale voltage generation circuit according to this embodiment.

Description of reference symbols

102: Digital/Analog Converter 104: Switch Circuit

106: output buffer

202: First digital/analog converter

204: first switch circuit 206: first output buffer

208: Second digital/analog converter

210: Second switch circuit 212: Second output buffer

214: Multi-tasker 302: Input terminal

304: ground terminal 306: voltage divider circuit

308: The first internal resistance string 310: The second internal resistance string

402: input terminal 404: ground terminal

406: Voltage divider circuit 408: The first internal resistor string

410: The second internal resistance string 502: High potential control signal

504: Low potential control signal 506: High potential control signal

508: Low potential control signal 510: High potential control signal

Detailed ways

The invention discloses a gray-scale voltage generating circuit. By controlling the switch in the gray-scale voltage generating circuit, the gray-scale voltage generating circuit can output the analog gray-scale voltage of the image or a common voltage, and the common voltage will cause the display to display a The common gray scale can be, for example, a black frame. The black screen can be displayed between normal video screens to reduce the smear phenomenon of dynamic images, or it can be displayed before system initialization, so that the display can display uniform black images at the initial start-up, so as to solve the problem of banding caused by the moment when the system is powered on. noise. In order to make the description of the present invention more detailed and complete, the following embodiments may be referred to and described in conjunction with FIG. 1 to FIG. 5 .

First embodiment:

Please refer to FIG. 1 , which is a schematic diagram of a gray scale voltage generating circuit according to a first embodiment of the present invention. The grayscale voltage generation circuit of this embodiment is located in the data driver, and at least includes a digital/analog converter 102 , a switch circuit 104 and an output buffer 106 . The switch circuit 104 at least includes a switch Q1 , a switch Q2 and an input terminal Vx, wherein the switch Q1 and the switch Q2 are in opposite phases (that is, the two switches are not turned on at the same time). The switch Q1 and the switch Q2 can be, for example, an N-type metal-oxide-semiconductor transistor (NMOS), a P-type metal-oxide-semiconductor transistor (PMOS), or other components that can be used as switches. The input terminal Vx can input any voltage value, such as GMA1, GMA10, V _COM . . . . The grayscale voltage generating circuit of this embodiment further includes at least a timing control circuit (not shown), which can generate control signals required for controlling the switches Q1 and Q2. In addition, in other embodiments of the present invention, a selector may also be included to be electrically connected to the input terminal Vx to select an input voltage from a plurality of reference voltage sources.

In this embodiment, the grayscale voltage generation circuit can use the control signal to control the switch Q1 and the switch Q2 to be turned on and off, so that the output buffer 106 outputs the analog grayscale voltage transmitted by the digital/analog converter 102 or the input terminal Vx The voltage value, so that the monitor displays a normal image or a black screen. Taking a vertical alignment (VA) liquid crystal display as an example, when the control signal is at a high potential (High), the switch Q1 is turned on, and the switch Q2 is not turned on, and the output buffer 106 will output the signal transmitted by the digital/analog converter 102 The analog grayscale voltage enables the display to display multiple different grayscales, that is, the display displays normal image images. And when the control signal is at low potential (Low), the switch Q1 is not conducting, and the switch Q2 is conducting. Since the voltage value of the input terminal Vx is V _COM , the output buffer 106 will output the voltage value of V _COM , so that the display will display a A common gray scale, for example, a monitor displays a black screen. In other embodiments of the present invention, the input terminal Vx can also input other values according to practical applications, so that the display displays a black screen.

Second embodiment:

Please refer to FIG. 2 , which is a schematic diagram of a gray scale voltage generating circuit according to a second embodiment of the present invention. This embodiment is especially suitable for twisted nematic (TN) liquid crystal displays. The grayscale voltage generating circuit of this embodiment is located in the data driver, and at least includes a first digital/analog converter 202, a first switch circuit 204, a first output buffer 206, and a second digital/analog converter 208 , a second switch circuit 210 , a second output buffer 212 and a multiplexer 214 . The first switch circuit 204 at least includes a switch Q1 , a switch Q2 and a first input terminal Vx ₁ , wherein the switch Q1 and the switch Q2 are in inverse phase. The second switch circuit 210 at least includes a switch Q3 , a switch Q4 and a second input terminal Vx ₂ , wherein the switch Q3 and the switch Q4 are inverted. The aforementioned switch can be, for example, an NMOS transistor, a PMOS transistor, or other components that can be used as switches. The grayscale voltage generating circuit of this embodiment further includes at least a timing control circuit (not shown), which can generate control signals required for controlling the switches Q1, Q2, Q3 and Q4.

In this embodiment, the gray scale voltage generation circuit can use the control signal to control the switch Q1, switch Q2, switch Q3 and switch Q4 on and off, so that the first output buffer 206 and the second output buffer 212 output the first output buffer respectively. The analog grayscale voltage transmitted by the first digital/analog converter 202 and the second digital/analog converter 208 may output the voltage values of the first input terminal _Vx1 and the second input terminal _Vx2 respectively, so that the display can display normal images or Black screen.

Taking a twisted nematic liquid crystal display as an example, in this embodiment, when the control signal is at a high potential, the switch Q1 and the switch Q3 are turned on, and the switch Q2 and the switch Q4 are not turned on, then the first output buffer 206 will pass through The multiplexer 214 outputs the first set of analog gray scale voltages transmitted by the first digital/analog converter 202, and the second output buffer 212 outputs the second set of analog gray scale voltages transmitted by the second digital/analog converter 208 through the multiplexer 214. A set of analog grayscale voltages enables the display to display multiple different grayscales, that is, the display displays normal image images. And when the control signal is at a low potential, the switch Q1 and the switch Q3 are not turned on, and the switch Q2 and the switch Q4 are turned on, because the voltage input from the first input terminal _Vx1 is GMA1 and the voltage input from the second input terminal _Vx2 is value is GMA10, then the first output buffer 206 will output the GMA1 voltage value through the multiplexer 214, and the second output buffer 212 will output the GMA10 voltage value through the multiplexer 214, so that the display can display a common gray scale, such as a display A black screen is displayed.

In addition, since this embodiment uses a twisted nematic liquid crystal display, and the twisted nematic liquid crystal display needs to periodically invert the liquid crystal, so this embodiment can use the multiplexer 214 to change the output signal sent to the first output buffer. 206 and the signal polarity of the second output buffer 212, so that the first output buffer 206 and the second output buffer 212 can periodically output positive polarity signals and negative polarity signals, which can reduce the output buffer quantity, reducing circuit complexity. In this embodiment, the multiplexer 214 makes the first output buffer 206 and the second output buffer 212 alternately output the first set of analog grayscale voltages/GMA1 voltage values and the second set of analog grayscale voltages according to another control signal. Voltage/GMA10 voltage value. For example, assuming that the first group of analog gray-scale voltages are positive polarity gray-scale voltages, and the second group of analog gray-scale voltages are negative polarity gray-scale voltages, and a POL control signal is used to control the output of the multiplexer 214, then When the POL control signal is high, the first output buffer 206 outputs a first set of grayscale voltages (positive polarity), and the second output buffer 212 outputs a second set of grayscale voltages (negative polarity). When the POL control signal is low, the first output buffer 206 outputs the second set of grayscale voltages (negative polarity), and the second output buffer 212 outputs the first set of grayscale voltages (positive polarity). Alternatively, when the POL control signal is at a high potential, the first output buffer 206 outputs the voltage value of GMA1 , and the second output buffer 212 outputs the voltage value of GMA10 . When the POL control signal is low, the first output buffer 206 outputs the voltage value of GMA10 , and the second output buffer 212 outputs the voltage value of GMA1 . The positive polarity signal and the negative polarity signal are alternately output from the first output buffer 206 and the second output buffer 212, so that the liquid crystal can be periodically inverted.

Third embodiment:

Please refer to FIG. 3 . FIG. 3 is a schematic diagram of a gray scale voltage generating circuit according to a third embodiment of the present invention. This embodiment is suitable for twisted nematic liquid crystal displays. The grayscale voltage generating circuit of this embodiment at least includes an input terminal 302, a ground terminal 304, a voltage divider circuit 306, a plurality of switches (switch Q1 to switch Q8), a first internal resistor string 308 and a second internal resistor String 310. The input terminal 302 is used to input a reference voltage (V _REF ); the ground terminal 304 is used to input a ground voltage; the voltage divider circuit 306 is electrically connected between the input terminal 302 and the ground terminal 304, and the voltage divider circuit 306 includes 10 resistors (R1~R10), used to divide the 10 gray scale voltages (GMA1~GMA10); the switches Q1 to Q8 are electrically connected to the voltage divider circuit 306 respectively, and can be controlled by a control signal to make the gray scale The voltage generating circuit outputs the above-mentioned grayscale voltages (GMA1˜GMA10) or fixed voltages (GMA1 and GMA10). The first internal resistor string 308 is electrically connected to the input terminal 302 and part of the voltage divider circuit, and the second internal resistor string 310 is electrically connected between the remaining voltage divider circuits. The first internal resistor string 308 and the second internal resistor string 310 can connect 10 The gray-scale voltages are further divided into a first group of gray-scale voltages (V0-V63) and a second group of gray-scale voltages (V'0-V'63), as shown in FIG. 3 . The aforementioned switch can be, for example, an NMOS transistor, a PMOS transistor, or other components that can be used as switches. The grayscale voltage generating circuit of this embodiment further includes at least a timing control circuit (not shown), which can generate control signals required for controlling the switches Q1 to Q8.

In this embodiment, the gray-scale voltage generation circuit can use the control signal to control whether the switches Q1 to Q8 are turned on or not, so as to output the first set of gray-scale voltages and the second set of gray-scale voltages or the voltages of GMA1 and GMA10 Value to a digital / analog converter, and then make the monitor display a normal image or a black screen.

In this embodiment, when the control signal is at a high potential, the switches Q1 to Q8 are turned on, and the voltage divider circuit 306 operates normally to divide the input reference voltage to generate 10 gray scale voltages (GMA1-GMA10). , and then divide the voltage by the first internal resistor string 308 and the second internal resistor string 310, so that the gray-scale voltage generation circuit outputs the first set of gray-scale voltages (V0-V63) and the second set of gray-scale voltages (V'0-V '63) to the digital/analog converter, so that the display can display a plurality of different gray scales, that is, the display can display normal image images. And when the control signal is at low potential, the switches Q1 to Q8 are not conducting, the first internal resistor string 308 and the second internal resistor string 310 are in a floating state, and the gray scale voltage generating circuit outputs the voltage value of GMA1 (V0-V63 Both are equal to GMA1) and GMA10 voltage value (V'0~V'63 are all equal to GMA10) to the digital/analog converter, so that the positive polarity output buffer in the data driver outputs the GMA1 voltage value, and makes the negative polarity output The buffers all output the GMA10 voltage value, so that the display can display a common gray scale, for example, the display can display a black screen.

Fourth embodiment:

Next, please refer to FIG. 4 , which is a schematic diagram of a grayscale voltage generation circuit according to a fourth embodiment of the present invention. The grayscale voltage generation circuit of this embodiment at least includes an input terminal 402, a ground terminal 404, a voltage divider circuit 406, a plurality of switches (switch Q1 to switch Q10), a first internal resistor string 408, and a second internal resistor The string 410 , a first input terminal Vx ₁ , a second input terminal Vx ₂ , a switch Q11 and a switch Q12, wherein the switches Q1 to Q10 are in opposite phases to the switch Q11, and the switches Q11 and the switch Q12 are in phase. The input terminal 402 is used to input a reference voltage (V _REF ); the ground terminal 404 is used to input a ground voltage; the voltage divider circuit 406 is electrically connected between the input terminal 402 and the ground terminal 404, and the voltage divider circuit 406 includes 10 resistors (R1-R10) are used to divide and output 10 gray scale voltages (GMA1-GMA10); one end of the switch Q1 to the switch Q10 is electrically connected to the input terminal 402 and the voltage dividing circuit 406 respectively. The first internal resistor string 408 is electrically connected to the switch Q1 to the other end of the switch Q5, and the second internal resistor string 410 is electrically connected to the switch Q6 to the other end of the switch Q10. The first internal resistor string 408 and the second internal resistor string 410 can connect 10 The gray-scale voltages are further divided into a first group of gray-scale voltages (V0-V63) and a second group of gray-scale voltages (V'0-V'63), as shown in FIG. 4 .

The switch Q11 is electrically connected between the switch Q1 and the first internal resistor string 408, and the switch Q11 is electrically connected to the first input terminal Vx ₁ , the switch Q12 is electrically connected between the switch Q10 and the second internal resistor string 410, and the switch Q12 is electrically connected Connect to the second input terminal Vx ₂ . Switch Q1 to switch Q10, switch Q11 and switch Q12 can be controlled by a control signal to turn on or not, so that the gray-scale voltage generating circuit outputs the above-mentioned gray-scale voltage (GMA1-GMA10) or outputs the first input terminal _Vx1 and the second input terminal Vx1. The voltage value of terminal Vx ₂ . The aforementioned switch can be, for example, an NMOS transistor, a PMOS transistor, or other components that can be used as switches. The grayscale voltage generating circuit of this embodiment further includes at least a timing control circuit (not shown), which can generate control signals required for controlling the switches Q1 to Q10, the switch Q11 and the switch Q12.

In this embodiment, the gray-scale voltage generating circuit can use the control signal to control whether the switches Q1 to Q10, the switch Q11, and the switch Q12 are turned on or not, so as to output the first set of gray-scale voltages and the second set of gray-scale voltages or The voltage values of the first input terminal _Vx1 and the second input terminal _Vx2 are output to a digital/analog converter, so that the display can display a normal image or a black picture.

Taking the vertical alignment liquid crystal display as an example, when the control signal is at a high potential, the switches Q1 to Q10 are turned on, and the switches Q11 and Q12 are not turned on, so the voltage divider circuit 406 operates normally to divide the input reference voltage. to generate 10 gray-scale voltages (GMA1-GMA10), and then divide the voltage through the first internal resistor string 408 and the second internal resistor string 410, so that the gray-scale voltage generating circuit outputs the first set of gray-scale voltages (V0-V63) and The second group of grayscale voltages (V'0-V'63) are sent to the digital/analog converter, and then the display can display multiple different grayscales, that is, the display displays normal image images. And when the control signal is at a low potential, the switches Q1 to Q10 are not conducting, and the switches Q11 and Q12 are conducting, so the first internal resistor string 408 and the second internal resistor string 410 are in a floating state, because the first input The voltage values input by the terminal Vx ₁ and the second input terminal Vx ₂ are both V _COM , then V0-V63 and V'0-V'63 are all equal to the voltage value of V _COM , and the gray scale voltage generating circuit will output the voltage value of V _COM In the digital/analog converter, the output buffer in the data driver outputs the V _COM voltage value, and then the display displays a common gray scale, for example, the display displays a black screen.

Next, taking the twisted nematic liquid crystal display as an example, when the control signal is at a high potential, the switches Q1 to Q10 are turned on, and the switches Q11 and Q12 are not turned on, then the voltage divider circuit 406 operates normally, and the input reference The voltage is divided to generate 10 gray scale voltages (GMA1~GMA10), and then divided by the first internal resistor string 408 and the second internal resistor string 410, so that the gray scale voltage generation circuit outputs the first group of gray scale voltages (V0 ~V63) and the second group of grayscale voltages (V'0~V'63) are sent to the digital/analog converter, so that the display can display multiple different grayscales, that is, the display can display normal image images. And when the control signal is at a low potential, the switches Q1 to Q10 are not turned on, and the switches Q11 and Q12 are turned on, then the first internal resistor string 408 and the second internal resistor string 410 are both in a floating state, because the first The voltage value input to the input terminal Vx ₁ is GMA1 and the voltage value input to the second input terminal Vx ₂ is GMA10, then V0-V63 is equal to GMA1 and V'0-V'63 is equal to GMA10, and the gray scale voltage generating circuit will output the GMA1 voltage value and GMA10 voltage value to the digital/analog converter, so that the positive polarity output buffers in the data driver output the GMA1 voltage value, and the negative polarity output buffers all output the GMA10 voltage value, so that the display can display a common gray scale For example, the monitor displays a black screen. In other embodiments of the present invention, the voltage values input by the first input terminal Vx ₁ and the second input terminal Vx ₂ can also be given different voltage values according to actual needs, so that the display can display a black screen.

Next, please refer to FIG. 5 . FIG. 5 shows a schematic diagram of timing control for generating a black frame by the gray scale voltage generation circuit according to this embodiment. When the timing control circuit sends out the control signal shown in Figure 5, the effect of black screen insertion can be achieved. For example, when the control signal is at high potential (502, 506, and 510), the switches Q1 to Q10 are turned on, and the switches Q11 and Q12 are not turned on, and the gray-scale voltage generating circuit will output the first set of gray-scale voltages (V0-V63) and the second set of gray-scale voltages (V'0-V'63), the data driver will operate normally at this time, and the display will display a normal picture. And when the control signal is at low potential (504 and 508), the switches Q1 to Q10 are not turned on, the switches Q11 and Q12 are turned on, and the gray scale voltage generation circuit will output the first input terminal _Vx1 and the second input terminal At the voltage value of Vx ₂ , the liquid crystal display displays a black screen at this time, because the rapid switching of the display cycle can effectively improve the smear phenomenon and improve the display quality of the display.

It is worth mentioning that, in each embodiment of the present invention, it is only necessary to output a control signal from the timing control circuit to control whether each switch is turned on or not, so that the screen output of the display can be controlled to be a normal screen or a black screen. In addition, the voltage values of the input terminals are only examples. In other embodiments of the present invention, the voltage values of the input terminals can also be given different voltage values according to actual needs.

It can be seen from the above-mentioned embodiments of the present invention that one advantage of the present invention is that the gray-scale voltage generating circuit of the present invention can control the switch in the gray-scale voltage generating circuit to make the gray-scale voltage generating circuit output a fixed voltage value to Make the display produce a black screen, which can solve the band noise generated by the thin film transistor liquid crystal display at the moment of system power supply.

It can be seen from the above-mentioned embodiments of the present invention that another advantage of the present invention is that the gray-scale voltage generating circuit of the present invention can use the switch in the gray-scale voltage generating circuit to generate a black picture without additional input of a black picture system signal or By switching the backlight module on and off, the smear problem of the thin film transistor liquid crystal display can be solved.

It can be seen from the above-mentioned embodiments of the present invention that another advantage of the present invention is that the switches provided in the grayscale voltage generating circuit can be directly formed by the data driver process, so the cost of parts can be saved, and because the switches are directly arranged in the data driver , so it is easier to achieve high frequency operation.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The protection scope of the invention shall be determined by the claims of the present invention.

Claims (10)

1. A display device, at least including: A gray-scale voltage generation circuit capable of generating a first set of gray-scale voltages according to a first set of reference voltages in a first time period, and capable of generating a second set of gray-scale voltages according to a second set of reference voltages , wherein the first set of reference voltages is different from the second set of reference voltages; and A liquid crystal panel, in a first time period, receives the first group of gray-scale voltages to display a plurality of different gray-scale levels, and in a second time period, receives the second group of gray-scale voltages to display a common gray scale, Wherein the grayscale voltage generation circuit at least further includes: a plurality of voltage dividing circuits, electrically connected between a first voltage terminal and a second voltage terminal, and these voltage dividing circuits are used to generate the first set of reference voltages; A plurality of switches, wherein one end of each of these switches is electrically connected to some of these voltage dividing circuits; a first internal resistor string electrically connecting a maximum of the first set of reference voltages to the other end of some of the switches; and A second internal resistor string, electrically connected to a minimum of the first set of reference voltages and the other ends of the remaining switches, the first internal resistor string and the second internal resistor string can divide the first set of reference voltages is the output of the first group of gray scale voltages; Wherein, during the first time period, these switches are turned on, and the gray-scale voltage generation circuit outputs the first group of gray-scale voltages through the first internal resistor string and the second internal resistor string, so that the liquid crystal panel To display these different gray scales, during the second time period, the switches are not turned on, the second set of reference voltages is the maximum and the minimum of the first set of reference voltages, the gray scale voltage generating circuit Outputting the second set of grayscale voltages through the first internal resistor string and the second internal resistor string, so that the liquid crystal panel displays the common grayscale level, and the second set of grayscale voltages is the first set of reference voltages The largest and the smallest of . 2. A display device, including at least: A gray-scale voltage generation circuit capable of generating a first set of gray-scale voltages according to a first set of reference voltages in a first time period, and capable of generating a second set of gray-scale voltages according to a second set of reference voltages , wherein the first set of reference voltages is different from the second set of reference voltages; and A liquid crystal panel, in a first time period, receives the first group of gray-scale voltages to display a plurality of different gray-scale levels, and in a second time period, receives the second group of gray-scale voltages to display a common gray scale, Wherein the grayscale voltage generation circuit at least further includes: A plurality of voltage dividing circuits, electrically connected between a first voltage terminal and a second voltage terminal, these voltage dividing circuits are used to generate the first set of reference voltages; A plurality of first switches, wherein one end of each of these first switches is respectively electrically connected to the first voltage end and each of these voltage dividing circuits; A first internal resistor string electrically connected to the other ends of the first switches of the first part; A second internal resistor string, electrically connected to the other ends of the remaining first switches, the first internal resistor string and the second internal resistor string can divide the first set of reference voltages into the first set of gray scale voltage output ; A second switch, electrically connected between one of the first switches and the first internal resistance string, the second switch is opposite to the first switches; a third switch, electrically connected between another one of the first switches and the second internal resistance string, the third switch is in antiphase with the first switches; a first input terminal electrically connected to the second switch for inputting the second set of reference voltages; and a second input terminal electrically connected to the third switch for inputting the rest of the second set of reference voltages; Wherein, in the first time period, the first switches are turned on, the second switch and the third switch are not turned on, and the gray scale voltage generation circuit uses the first internal resistor string and the second internal resistor Outputting the first group of grayscale voltages in series, so that the liquid crystal panel displays these different grayscales, and during the second time period, the first switches are not conducting, and the second switch and the third switch are conducting , the gray-scale voltage generating circuit outputs the second set of gray-scale voltages through the first internal resistor string and the second internal resistor string, so that the liquid crystal panel displays the common gray-scale level, and the second set of gray-scale voltages is the second set of reference voltages. 3. The display device as claimed in claim 2, when the display device is a vertical alignment liquid crystal display, the second set of reference voltages input to the first input terminal and the second input terminal are equal to the V _COM voltage. 4. The display device according to claim 2, when the display device is a twisted nematic liquid crystal display, the part of the second set of reference voltages input to the first input terminal is equal to the maximum of the first set of reference voltages, The rest of the second group of reference voltages input to the second input terminal are equal to the minimum of the first group of reference voltages. 5. The display device as claimed in claim 2, wherein the grayscale voltage generating circuit further comprises at least a timing control circuit for outputting a control signal for controlling the switches. 6. A display device, at least including: A grayscale voltage generation circuit, including: A first voltage terminal for inputting a first reference voltage; a second voltage terminal for inputting a second reference voltage; a plurality of voltage dividing circuits, electrically connected between the first voltage terminal and the second voltage terminal, for generating a plurality of divided voltages; a plurality of switches, wherein one end of each of these switches is electrically connected to part of the voltage dividing circuit; a first internal resistor string, electrically connected to the maximum of the divided voltages and the other ends of some of the switches, the first internal resistor string can divide some of these divided voltages into a first group of gray scale voltage output; and a second internal resistor string electrically connected to the smallest of the divided voltages and the other ends of the remaining switches, the second internal resistor string can divide the remaining divided voltages into a second group of gray scale voltages for output; and A liquid crystal panel, in a first time period, receives the first group of gray-scale voltages and the second group of gray-scale voltages to display a plurality of different gray-scale levels, and in a second time period, outputs these divided voltages The maximum of these partial pressures and the minimum to display a common gray scale; Wherein, during the first time period, these switches are turned on, and the gray-scale voltage generation circuit outputs the first group of gray-scale voltages and the second group of gray-scale voltages through the first internal resistor string and the second internal resistor string In the second time period, these switches are not turned on, and the gray scale voltage generating circuit outputs the maximum of these divided voltages and the value of these divided voltages through the first internal resistor string and the second internal resistor string. the smallest. 7. A display device, at least including: A grayscale voltage generation circuit, including: a first voltage terminal for inputting a first reference voltage; a second voltage terminal for inputting a second reference voltage; a plurality of voltage dividing circuits, electrically connected between the first voltage terminal and the second voltage terminal, for generating a plurality of divided voltages; A plurality of first switches, wherein one end of each of these first switches is respectively electrically connected to the first voltage end and each of these voltage dividing circuits; A first internal resistance string, electrically connected to the other end of the first part of the first switches, the first internal resistance string can divide some of these divided voltages into a first group of gray scale voltage output; A second internal resistor string, electrically connected to the other ends of the remaining first switches, the second internal resistor string can divide the remaining voltages into a second group of gray scale voltages for output; A second switch, electrically connected between one of the first switches and the first internal resistance string, the second switch is opposite to the first switches; A third switch, electrically connected between another one of the first switches and the second internal resistance string, the third switch is in antiphase with the first switches; a third voltage terminal electrically connected to the second switch, the third voltage terminal is used for inputting a third reference voltage; and a fourth voltage terminal electrically connected to the third switch, the fourth voltage terminal is used to input a fourth reference voltage; and A liquid crystal panel, in a first time period, receives the first set of gray scale voltages and the second set of gray scale voltages to display multiple different gray scales, and in a second time period, receives the third set of gray scale voltages The reference voltage and the fourth reference voltage display a common gray scale; Wherein, in the first time period, the first switches are turned on, the second switch and the third switch are not turned on, and the gray scale voltage generation circuit uses the first internal resistor string and the second internal resistor Outputting the first group of gray-scale voltages and the second group of gray-scale voltages in series, during the second time period, the first switches are not conducting, the second switch and the third switch are conducting, and the gray-scale voltage The generating circuit outputs the third reference voltage and the fourth reference voltage through the first internal resistor string and the second internal resistor string. 8. The display device as claimed in claim 7, when the display device is a vertical alignment liquid crystal display, the third reference voltage and the fourth reference voltage are equal to V _COM voltage. 9. The display device according to claim 7, when the display device is a twisted nematic liquid crystal display, the third reference voltage is equal to the maximum of the first group of gray scale voltages, the fourth reference voltage is equal to the first The smallest of the two gray scale voltages. 10. The display device as claimed in claim 7, said gray scale voltage generation circuit at least further comprising a control circuit capable of outputting a control signal for controlling the switches. the

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