TW202009913A - Voltage compensation circuit, display device and method thereof - Google Patents

Abstract

A voltage compensation circuit is applied to a display device having a plurality of pixel circuit. The voltage compensation circuit includes a first switch circuit, a second switch circuit and a matching circuit. The first switch circuit is disposed on a printed circuit board, and electrically connected to a ground terminal and an output terminal. The first switch circuit is configured to receive a control signal and a data signal. The second switch circuit is disposed on the printed circuit board, and electrically connected to the first switch circuit and a first terminal. The second switch circuit is configured to receive the control signal, the data signal and a gate signal. The matching circuit is disposed on a glass base board, and electrically connected to the first switch circuit, the first terminal and a reference voltage. The matching circuit is configured to output a compensation voltage. The compensation voltage is configured to adjust a common voltage of a pixel circuit.

Description

Voltage compensation circuit, display device and voltage compensation method

This disclosure relates to a voltage compensation circuit, a voltage compensation method, and a display device, and more particularly to a voltage compensation circuit, a voltage compensation method, and a display device that use a test element to detect the aging condition of a thin film transistor.

Compared with low temperature poly-silicon thin film transistors (LTPS TFTs), amorphous silicon thin film transistors (a-Si TFTs) have a large capacity, The production process is shorter and the cost is lower. However, amorphous silicon thin film transistors are prone to aging with use time, so it is easy to cause problems such as flicker or image retention after long-term use of the liquid crystal display.

The invention provides a voltage compensation circuit, a voltage compensation method and a display device, which mainly use a test transistor on a glass substrate to simulate the aging degree of the pixel circuit, and then use the compensation circuit to detect the critical voltage of the test transistor. The common voltage is adjusted according to the critical voltage of the test transistor to achieve the effect of compensating the common voltage immediately according to the current aging degree of the transistor.

The first aspect of this case is to provide a voltage compensation circuit for a display device having a complex pixel circuit. The voltage compensation circuit includes a first switching circuit, a second switching circuit, and a matching circuit. The first switch circuit is disposed on the printed circuit board, and is electrically connected to the ground terminal and the output terminal for receiving control signals and data signals. The second switch circuit is disposed on the printed circuit board and is electrically connected to the first switch circuit and the first node for receiving control signals, data signals, and gate signals. The matching circuit is arranged on the glass substrate and is electrically connected to the first switch circuit, the first node and the reference voltage, and is used to output a compensation voltage according to the operating voltage, and the compensation voltage is used to adjust the common voltage of the pixel circuit.

The second aspect of this case is to provide a display device. The display device includes a pixel circuit, a voltage generating unit, and a voltage compensation circuit. The pixel circuit is provided on the glass substrate. The voltage generating unit is electrically coupled to the pixel circuit to generate a common voltage and input the common voltage to the pixel circuit. The voltage compensation circuit is electrically coupled to the voltage generating unit. The voltage compensation circuit includes: a first switching circuit, a second switching circuit, and a matching circuit. The first switch circuit is disposed on the printed circuit board and is electrically connected to the ground terminal and the output terminal for receiving control signals and data signals. The second switch circuit is disposed on the printed circuit board and is electrically connected to the first switch circuit and the first node for receiving control signals, data signals, and gate signals. The matching circuit is disposed on the glass substrate, and is electrically connected to the first switch circuit, the first node, and the reference voltage, and is used to output a compensation voltage according to the operating voltage, and the compensation voltage is used to adjust the common voltage of the pixel circuit.

The third aspect of the case is to provide a voltage compensation method suitable for a display device. The display device includes a matching circuit and a voltage compensation circuit. The voltage compensation method includes the following steps: the voltage compensation circuit receives a control signal, a data signal, and a gate signal ; When the control signal is disabled, the voltage compensation circuit outputs the data signal and the gate signal to the matching circuit; and when the control signal is enabled, the voltage compensation circuit generates a compensation voltage according to the operating voltage, and the compensation voltage Output to the voltage generating unit.

The disclosed voltage compensation circuit, voltage compensation method and display device can be provided with a test transistor on the glass substrate to simulate the aging degree of the pixel circuit, and then use the compensation circuit to detect the critical voltage of the test transistor according to the test transistor's The threshold voltage adjusts the common voltage to achieve the effect of instantly compensating the common voltage according to the current aging of the transistor.

100‧‧‧Display device

110‧‧‧Source drive circuit

120‧‧‧ gate drive circuit

130‧‧‧Voltage generating unit

140‧‧‧ voltage compensation circuit

141‧‧‧ First switch circuit

142‧‧‧ Second switch circuit

143‧‧‧ matching circuit

150‧‧‧ pixel circuit

400‧‧‧Voltage compensation method

G‧‧‧Glass substrate

AA‧‧‧Active area

OUT‧‧‧Output

CTS‧‧‧Control signal

DDS‧‧‧Data signal

DGS‧‧‧Gate signal

Vref‧‧‧Reference voltage

VDD‧‧‧Working voltage

Vcom‧‧‧Common voltage

T1~T6‧‧‧switch

DT‧‧‧Transistor

C1, C2‧‧‧Capacitance

R‧‧‧Resistance

N1, N2‧‧‧ Node

S410~S440‧‧‧Step

In order to make the above and other objects, features, advantages and embodiments of the disclosed document more obvious and understandable, the drawings are described as follows: FIG. 1 is a schematic diagram of a display device according to an embodiment of the disclosed document; FIG. 2 Is a schematic diagram of a voltage compensation circuit according to an embodiment of the present disclosure; FIG. 3 is a circuit diagram of a voltage compensation circuit according to an embodiment of the present disclosure; and FIG. 4 is a voltage compensation method according to an embodiment of the present disclosure flow chart.

The embodiments of the present invention will be described below in conjunction with related drawings. In the drawings, the same reference numerals indicate the same or similar elements or method flows.

Please refer to figure 1. FIG. 1 is a schematic diagram of a display device 100 according to an embodiment of the present disclosure. As shown in FIG. 1, the display device 100 includes a source driving circuit 110, a gate driving circuit 120, a voltage generating unit 130, a voltage compensation circuit 140 and a pixel circuit 150. The pixel circuit 150 is disposed on the active area AA on the glass substrate G. The voltage generating unit 130 is electrically coupled to the pixel circuit 150 for generating a common voltage Vcom, and inputs the common voltage Vcom to the pixel circuit 150. The voltage compensation circuit 140 is electrically coupled to the voltage generating unit 130. Part of the circuit of the voltage compensation circuit 140 is disposed on the glass substrate G, and the other part of the circuit is disposed on the printed circuit board.

In one embodiment, the voltage compensation circuit 140 may be disposed around the active area AA to detect the aging of the pixel circuits 150 in different areas. In another embodiment, if it is limited by the space limitation of the display device 100, it may be set only at a corner around the active area AA.

Please refer to figure 2. FIG. 2 is a schematic diagram of the voltage compensation circuit 140 according to an embodiment of the present disclosure. As shown in FIG. 2, the voltage compensation circuit 140 includes a first switching circuit 141, a second switching circuit 142, a matching circuit 143, and a capacitor C1. The first switch circuit 141 is disposed on the printed circuit board and is electrically connected to the ground terminal and the output terminal OUT for receiving the control signal CTS and the data signal DDS. The second switch circuit 142 is disposed on the printed circuit board and electrically connected to the first switch circuit 141 for receiving the control signal CTS, the data signal DDS and the gate signal DGS. The matching circuit 143 is disposed on the glass substrate G, and is electrically connected to the first switching circuit 141 and the reference voltage Vref to output a compensation voltage according to the operating voltage VDD. The compensation voltage is used to adjust the common voltage Vcom of the pixel circuit 150. The capacitor C1 is electrically connected to the first switch circuit 141, the output terminal OUT, and the ground terminal.

In an embodiment, the gate signals of the first three stages or the last three stages in the gate driving circuit 120 are dummy gate signals, and the first three stages or the last three stages of the source driving circuit 110 are The data signal is a dummy data signal (dummy data signal), so the voltage compensation circuit 140 can use the dummy gate signal and the dummy data signal as the gate signal DGS and the data signal DDS received by the voltage compensation circuit 140 to simulate the drawing The aging condition of the element circuit 150.

Please refer to Figure 3. FIG. 3 is a circuit diagram of the voltage compensation circuit 140 according to an embodiment of the present disclosure. As shown in FIG. 3, the first switch circuit 141 includes switches T1, T2, T3, and T4 and a resistor R. The first terminal of the switch T1 is electrically connected to the output terminal OUT, the second terminal of the switch T1 is electrically connected to the node N2, and the control terminal of the switch T1 is used to receive the control signal CTS. The first end of the switch T2 is electrically connected to the node N2, and the control end of the switch T2 is used to receive the control signal CTS. The first end of the switch T3 is electrically connected to the second end of the switch T2 and the node N1, and the control end of the switch T3 is used to receive the control signal CTS. The first end of the switch T4 is electrically connected to the matching circuit 143, the second end of the switch T4 is electrically connected to the ground, and the control end of the switch T4 is used to receive the control signal CTS. The first end of the resistor R is electrically connected to the node N2, and the second end of the resistor R is electrically connected to the operating voltage VDD.

Please continue to refer to FIG. 3, the second switch circuit 142 includes switches T5 and T6. The first end of the switch T5 is used to receive the gate signal DGS, the second end of the switch T5 is electrically connected to the node N1, and the control end of the switch T5 is used to receive the control signal CTS. The first end of the switch T6 is electrically connected to the second end of the switch T3. The second end of the switch T6 is used to receive the data signal DDS, and the control end of the switch T6 is used to receive the control signal CTS.

Please continue to refer to FIG. 3, the matching circuit 143 includes a transistor DT and a capacitor C2. The first terminal of the transistor DT is electrically connected to the second terminal of the switch T3, and the control terminal of the transistor DT is electrically connected to the node N1. The first end of the capacitor C2 is electrically connected to the second end of the transistor DT, and the second end of the capacitor C2 is electrically connected to the reference voltage Vref. The capacitor C2 is used to simulate the liquid crystal capacitor and the storage capacitor in the pixel circuit.

In one embodiment, the transistor DT may be implemented as an N-type amorphous silicon thin film transistor, the switches T1~T4 may be implemented as an N-type metal oxide semi-transistor, and the switches T5 and T6 may be implemented as P-type gold Oxygen semi-transistors, but this embodiment is not limited thereto. For example, switches T1~T4 can also be implemented as P-type metal oxide semi-transistors, and switches T5 and T6 can be implemented as N-type metal oxide semi-transistors. In this case, the enabling level of switches T1~T6 will also vary The implementation components are different.

Next, please refer to FIG. 4 for the operation mode of the voltage compensation circuit 140. FIG. 4 is a flowchart of a voltage compensation method 400 according to an embodiment of the present disclosure. As shown in FIG. 4, the voltage compensation method 400 first performs step S410. The voltage compensation circuit 140 receives the control signal CTS, the data signal DDS, and the gate signal DGS. In one embodiment, the control signal CTS is used to control the on and off of the switches T1 to T6 in the voltage compensation circuit 140. The voltage compensation circuit 140 is usually operated in a blanking period, and the control signal CTS can be automatically or manually Control, for example, the control signal CTS can be set to turn on once after a period of time or how many frames.

Next, the voltage compensation method 400 executes step S420. When the control signal CTS is at the disabled level, the voltage compensation circuit 140 outputs the data signal DDS and the gate signal DGS to the matching circuit 143. In one embodiment, when the control signal CTS is at the disabled level, the switches T1 to T4 are turned off, and the switches T5 and T6 are turned on, so that the control terminal of the transistor DT receives the gate signal DGS, The first end of the transistor DT receives the data signal DDS, so that the transistor DT can simulate the pixel circuit 150 in the active area AA during the operation of the pixel circuit 150, and it ages together with the pixel circuit 150.

Next, the voltage compensation method 400 executes step S430. When the control signal CTS is at the enable level, the voltage compensation circuit 140 generates a compensation voltage according to the operating voltage VDD, and outputs the compensation voltage to the voltage generating unit 130. In one embodiment, when the control signal CTS is at the enable level, the switches T1 to T4 are turned on, and the switches T5 and T6 are turned off. In this case, the gate and source of the transistor DT are connected to each other, so the transistor DT is a diode connected diode (diode connected), so that the transistor DT reads the criticality of the transistor DT according to the operating voltage VDD Voltage to generate the compensation voltage.

Next, the voltage compensation method 400 executes step S440. The voltage generating unit 130 adjusts the common voltage using one of the lookup table and the voltage calculation using the compensation voltage, and then inputs the common voltage to the pixel circuit 150. In one embodiment, after the voltage compensation circuit 140 reads the threshold voltage of the transistor DT, the common voltage Vcom may be adjusted according to a look-up table (LUT). In another embodiment, the threshold voltage of the transistor DT currently detected and the threshold voltage of the transistor DT at the time of shipment may be compared with each other, and the difference between the two is multiplied by a weight value to obtain the compensation voltage value Then, the common voltage Vcom can be obtained by adding the common voltage Vcom. However, there are many ways to adjust the common voltage Vcom, and the disclosure is not limited to this.

In summary, the voltage compensation circuit, the voltage compensation method and the display device of the present disclosure can be provided with a test transistor on the glass substrate to simulate the aging degree of the pixel circuit, and use the pseudo gate signals of the first three stages or the last three stages And the false data signal allows the test transistor to age synchronously with the pixel circuit in the active area, and then use the compensation circuit to detect the critical voltage of the test transistor, and then adjust the common voltage according to the critical voltage of the test transistor The effect of current aging on the common voltage compensation immediately.

Certain words are used in the specification and patent application scope to refer to specific elements. However, those of ordinary skill in the art should understand that the same elements may be referred to by different nouns. The specification and the scope of patent application do not use the difference in names as the way to distinguish the components, but the difference in the functions of the components as the basis for distinguishing. "Inclusion" mentioned in the description and patent application scope is an open term, so it should be interpreted as "including but not limited to". In addition, "coupling" includes any direct and indirect connection means. Therefore, if it is described that the first element is coupled to the second element, it means that the first element can be directly connected to the second element through electrical connection, wireless transmission, optical transmission, or other signal connection, or through other elements or connections The means is indirectly electrically or signally connected to the second element.

In addition, unless otherwise specified in the description, any singular case also includes the meaning of the plural case.

The above are only preferred embodiments of the present invention, and any equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the present invention.

100‧‧‧Display device

110‧‧‧Source drive circuit

120‧‧‧ gate drive circuit

130‧‧‧Voltage generating unit

140‧‧‧ voltage compensation circuit

150‧‧‧ pixel circuit

G‧‧‧Glass substrate

AA‧‧‧Active area

CTS‧‧‧Control signal

Vcom‧‧‧Common voltage

Claims (14)

A voltage compensation circuit applied to a display device having a complex pixel circuit, including: a first switch circuit, which is arranged on a printed circuit board, and is electrically connected to a ground terminal and an output terminal for receiving a control Signal and a data signal; a second switch circuit, disposed on the printed circuit board, electrically connected to the first switch circuit and a first node, for receiving the control signal, the data signal and a gate signal ; And a matching circuit, set on a glass substrate, electrically connected to the first switch circuit, the first node and a reference voltage, for outputting a compensation voltage according to an operating voltage, the compensation voltage is used to adjust the A common voltage of these pixel circuits. The voltage compensation circuit according to claim 1 further includes: a capacitor electrically connected to the first switching circuit, the output terminal, and the ground terminal. The voltage compensation circuit of claim 1, wherein the first switch circuit further includes: a first switch having a first terminal, a second terminal, and a first control terminal, the first terminal is electrically connected to The output terminal, the second terminal is electrically connected to a second node, the first control terminal is used to receive the control signal; a second switch has a third terminal, a fourth terminal and a second control terminal , The third terminal is electrically connected to the second node, the second control terminal is used to receive the control signal; a third switch has a fifth terminal, a sixth terminal and a third control terminal, the first Five terminals are electrically connected to the fourth terminal, the second switch circuit and the matching circuit, the third control terminal is used to receive the control signal; a fourth switch has a seventh terminal, an eighth terminal and a A fourth control terminal, the seventh terminal is electrically connected to the matching circuit, the eighth terminal is electrically connected to the ground terminal, the fourth control terminal is used to receive the control signal; and a resistor has a ninth terminal And a tenth terminal, the ninth terminal is electrically connected to the second node, and the tenth terminal is electrically connected to the operating voltage. The voltage compensation circuit of claim 3, wherein the first switch, the second switch, the third switch, and the fourth switch are N-type metal oxide semiconductors. The voltage compensation circuit according to claim 1, wherein the first voltage stabilizing circuit includes: a fifth switch having a first terminal, a second terminal and a first control terminal, the first terminal is used to receive the gate Pole signal, the second terminal is electrically connected to the first node, the first control terminal is used to receive the control signal; and a sixth switch has a third terminal, a fourth terminal and a second control terminal The third terminal is electrically connected to the first switch circuit, the fourth terminal is used to receive the data signal, and the second control terminal is used to receive the control signal. The voltage compensation circuit according to claim 5, wherein the fifth switch and the sixth switch are P-type metal oxide semi-transistors. The voltage compensation circuit of claim 1, wherein the matching circuit further includes: a transistor having a first terminal, a second terminal, and a first control terminal, the first terminal is electrically connected to the first Switching circuit, the first control terminal is electrically connected to the first node; and a second capacitor has a third terminal and a fourth terminal, the third terminal is electrically connected to the second terminal, the fourth The terminal is electrically connected to the reference voltage. The voltage compensation circuit according to claim 1, wherein when the control signal is at a low level, the first switch circuit is in an off state, and the second switch circuit is in an on state, so that the matching circuit receives the data signal and The gate signal. The voltage compensation circuit of claim 1, wherein when the control signal is at a high level, the first switch circuit is in an on state and the second switch circuit is in an off state, so that the matching circuit generates the compensation according to the operating voltage Voltage and output the compensation voltage to a voltage generating unit. The voltage compensation circuit according to claim 9, wherein the voltage generating unit uses the compensation voltage in conjunction with one of a lookup table and a voltage calculation to adjust the common voltage. A display device includes: a pixel circuit disposed on a glass substrate; a voltage generating unit electrically coupled to the pixel circuit for generating a common voltage and inputting the common voltage to the pixel circuit; And a voltage compensation circuit electrically coupled to the voltage generating unit, the voltage compensation circuit includes: a first switch circuit, disposed on a printed circuit board, electrically connected to a ground terminal and an output terminal for Receiving a control signal and a data signal; a second switch circuit is provided on the printed circuit board and is electrically connected to the first switch circuit and a first node for receiving the control signal, the data signal and a Gate signal; and a matching circuit, which is arranged on the glass substrate and electrically connected to the first switch circuit, the first node and a reference voltage, for outputting a compensation voltage according to an operating voltage, the compensation voltage is used To adjust the common voltage of the pixel circuit. A voltage compensation method is suitable for a display device. The display device includes a matching circuit and a voltage compensation circuit. The voltage compensation method includes: the voltage compensation circuit receives a control signal, a data signal, and a gate signal; When the control signal is at a disabled level, the voltage compensation circuit outputs the data signal and the gate signal to the matching circuit; and when the control signal is at a consistent level, the voltage compensation circuit generates a Compensate the voltage and output the compensated voltage to a voltage generating unit. The voltage compensation method according to claim 12, further comprising: the voltage generating unit using the compensation voltage in conjunction with one of a look-up table and a voltage calculation to adjust a common voltage; and inputting the common voltage to a pixel circuit . The voltage compensation method according to claim 12, wherein when the control signal is the enable level, the voltage compensation circuit outputs the operating voltage to the matching circuit, and the matching circuit generates the compensation voltage according to the operating voltage.

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