TWI817517B - Scan driving circuit and method of controlling the same - Google Patents

Abstract

A scan driving circuit including a plurality of scan switch circuits is provided. The plurality of scan switch circuits is respectively coupled to a plurality of rows of pixel units for sequentially conducting the plurality of rows of pixel units. Each of the scan switch circuits has a total on-state resistance, and each includes a switch circuit and a resistance control circuit. The switch circuit is selectively conducted according to a switch signal to receive a current from one of the plurality of rows of pixel units. The resistance control circuit is coupled to the switch circuit to receive the current, and is configured to adjust an on-state resistance of the resistance control circuit according to at least one resistance control signal. The total on-state resistance is a sum of an on-state resistance of the switch circuit and the on-state resistance of the resistance control circuit, or a reciprocal of the total on-state resistance is a sum of a reciprocal of the on-state resistance of the switch circuit and a reciprocal of the on-state resistance of the resistance control circuit.

Description

Scan driving circuit and control method thereof

This disclosure document relates to the driving technology of diode displays, in particular to a scan driving circuit that can adaptively adjust the load and its control method.

With the development of display technology, the shape of the display device is no longer limited to the traditional rectangle, and can be a triangle or other shapes. However, the fact that the display device is not square means that the number of pixel units in each row (row) of the display device will not be exactly the same. In this case, when the display signals sent to each column are the same (for example, displaying a solid color screen), due to the load difference of each column, there will be a problem of different brightness of each column, further affecting the performance of the display device (especially low-frequency grayscale).

Therefore, how to solve the problem of uneven brightness during display of a non-rectangular display device is an issue in this field.

In order to solve the above problem, this disclosure document provides a scan driving circuit including a plurality of scan switch circuits. A plurality of scan switch circuits are respectively coupled to multiple columns of pixel units for sequential conduction to sequentially drive multiple columns of pixel units. Each of the scan switch circuits has a total on-resistance value, and each includes a switch circuit and a resistance control. circuit. The switch circuit has an on-resistance value for selectively conducting according to the switch signal to receive current from one of the plurality of rows of pixel units. The resistance control circuit has an on-resistance value and is coupled to the switch circuit to receive current and adjust the on-resistance value of the resistance control circuit according to at least one resistance control signal. Among them, the total on-resistance value is the sum of the on-resistance value of the switching circuit and the on-resistance value of the resistance control circuit, or the reciprocal of the total on-resistance value is the reciprocal of the on-resistance value of the switching circuit and the on-resistance value of the resistance control circuit. The sum of the reciprocals of the on-resistance values.

This disclosure document further provides a control method suitable for a scan drive circuit, wherein the scan drive circuit includes a plurality of scan switch circuits, the plurality of scan switch circuits are respectively coupled to a plurality of columns of pixel units, wherein each of the plurality of scan switch circuits has The total on-resistance value, and each includes a switching circuit and a resistance control circuit, wherein the switching circuit and the resistance control circuit each have an on-resistance value, and the control method includes: (a) using at least one resistance control signal to control the resistance control circuit, so that The resistance control circuit adjusts the on-resistance value of the resistance control circuit according to at least one resistance control signal, (b) uses the switch signal to turn on the switch circuit, and (c) repeats steps (a) and (b) to turn on multiple scans in sequence Switch circuits to sequentially drive multiple columns of pixel units. Among them, the total on-resistance value is the sum of the on-resistance value of the switching circuit and the on-resistance value of the resistance control circuit, or the reciprocal of the total on-resistance value is the reciprocal of the on-resistance value of the switching circuit and the on-resistance value of the resistance control circuit. The sum of the reciprocals of the on-resistance values.

The advantage of the above-mentioned scan drive circuit and control method is that when the load of each scan line is different, the total on-resistance value of each scan switch circuit can be controlled to ensure that the potential of the pixel units in multiple columns when lit is more accurate. average, thereby achieving uniform brightness.

In this disclosure document, when a component is referred to as "connected" or "coupled," it may mean "electrically connected" or "electrically coupled." "Connection" or "coupling" can also be used to indicate the coordinated operation or interaction between two or more elements. In addition, although terms such as “first”, “second”, etc. are used in this disclosure document to describe different components, these terms are only used to distinguish components or operations described by the same technical terms. Unless the context clearly indicates otherwise, such terms do not specifically refer to or imply a sequence or sequence, nor are they intended to limit this disclosure document.

Figure 1 is a functional block diagram of a display device 1 according to some embodiments. The display device 1 includes a scan drive circuit 10, a display drive circuit 12, a timing control circuit 14, data lines DL[1]~DL[N], scan lines SL[1]~SL[M], and a pixel unit P[11] ~P[1N], P[21]~P[2(N-1)], ..., P[M1] (for the sake of brevity, it is marked as "P[11]~P[M1]" below), Where M and N are integers greater than 1. Among them, the scan driving circuit 10 further includes scan switch circuits 10_1~10_M.

Structurally, in some embodiments, each pixel unit P[11]~P[M1] is implemented with a light-emitting diode, and the anode of the diode in each row (column) is electrically connected to the data line DL. One of [1]~DL[N], the cathode of the diode in each column (row) is electrically connected to one of the scan lines SL[1]~SL[M]. The scan lines SL[1]~SL[M] are coupled to the scan switch circuits 10_1~10_M respectively. In some embodiments, the active area of the display device 1 (ie, the area that provides a picture) is triangular, so the number of pixel units in multiple rows is different from each other, and the number of pixel units in multiple columns is also different from each other.

The pixel units P[11]~P[M1] are coupled to the display driver circuit 12 through the data lines DL[1]~DL[N], and coupled to the scan driver through the scan lines SL[1]~SL[M]. Scan switch circuits 10_1~10_M in circuit 10. The display driving circuit 12 is used to provide current to the data lines DL[1]~DL[N]. The scan switch circuits 10_1~10_M are used to select (that is, drive or light) the pixel units P[11]~P[M1] column by column. For example, the scan switch circuits 10_1~10_M can provide the ground voltage GND in sequence. to scan lines SL[1]~SL[M], but this disclosure document is not limited to this.

The timing control circuit 14 is coupled to the scan driving circuit 10 and the display driving circuit 12 for transmitting various timing control signals such as a horizontal synchronization signal (Hsync), a vertical synchronization signal (Vsync), one or more clock signals, etc. to the scan driving circuit. 10 and the display driving circuit 12 to control the operation timing of the scanning driving circuit 10 and the display driving circuit 12 . The timing control circuit 14 can also be used to provide display data to the display driving circuit 12 to specify the grayscale value of each of the pixel units P[11]~P[M1].

The loads on the scan lines SL[1]~SL[M] are directly related to the number of pixel units coupled to them. In some cases, when the loads on the scan lines SL[1]~SL[M] are different from each other, and the electrical properties of the scan switch circuits 10_1~10_M are not adapted according to the loads on the scan lines SL[1]~SL[M] When adjusting, the pixel units P[11]~P[M1] may have different brightness stabilization times or uneven brightness due to the current-voltage drop (IR drop) effect. For example, the picture of the scan line SL[1] Pixel units P[11]~P[1N] may be the slowest to reach stable brightness or have the lowest brightness. Diode displays usually use pulse width modulation (PWM) technology. The grayscale value displayed by a pixel unit depends on its enabling time. When the brightness takes longer to stabilize, the more likely the pixel unit is to produce Grayscale errors, especially in the case of low grayscale displays. In order to overcome the above problems, this disclosure document proposes a scan driving circuit 10 in which the scan switch circuits 10_1 ~ 10_M each have a variable on-state resistance R _total . For example, when the current on the scan line SL[1] is transmitted to the ground terminal of the ground voltage GND through the current path in the scan switch circuit 10_1, the resistance value on the current path is the total on-resistance value of the scan switch circuit 10_1 R _total , the total on-resistance value R _total of the other scanning switch circuits 10_2 ~ 10_M is defined in a manner similar to the aforementioned description of the total on-resistance value R _total of the scanning switch circuit 10_1. For the sake of simplicity, it will not be repeated here. .

The scan switch circuits 10_1 ~ 10_M have similar components, connection relationships, and operations. For the sake of simplicity, the scan switch circuit 10_1 will be described below. Figures 2A to 2C are circuit schematic diagrams of the scan switch circuit 10_1 according to some embodiments. In FIG. 2A , the scan switch circuit 10_1 includes a switch circuit 100 and a resistance control circuit 102 . The switch circuit 100 is coupled to the scan line SL[1] and has an on-resistance value R _C (shown in FIG. 3 ) for selectively conducting according to the switch signal SS from the timing control circuit 14 to switch from the scan line SL to the scan line SL[1]. [1] Receive current. In detail, the switch circuit 100 includes a transistor TS. The transistor TS is coupled between the scan line SL[1] and the resistance control circuit 102 for selectively conducting according to the switch signal SS. The resistance control circuit 102 includes a variable resistor VR and is coupled in series to the switch circuit 100 to receive current to adjust the resistance value of the variable resistor VR according to the resistance control signal RS from the timing control circuit 14. The resistance control circuit 102 has a conductor. The on-resistance value _RT (shown in Figure 3), in this embodiment, the on-resistance value _RT is the resistance value of the variable resistor VR. Therefore, the total on-resistance value R _total of the scan switch circuit 10_1 is the sum of the on-resistance value R _C and the on-resistance value _RT .

The scan switch circuit 10_1 in FIG. 2B is similar to the scan switch circuit 10_1 in FIG. 2A, so the differences will be described below.

In FIG. 2B , the resistance control circuit 102 has transistors T1 - T3 connected in parallel with each other, and the transistors T1 - T3 are coupled in series to the switch circuit 100 to receive current. The transistor T1 has an on-resistance value R _T1 (shown in FIG. 3 ) for selectively conducting according to the resistance control signal RS1 from the timing control circuit 14 . The transistor T2 has an on-resistance value R _T2 (shown in FIG. 3 ) for selectively conducting according to the resistance control signal RS2 from the timing control circuit 14 . The transistor T3 has an on-resistance value R _T3 (shown in FIG. 3 ) for selectively conducting according to the resistance control signal RS3 from the timing control circuit 14 . According to the resistance control signals RS1~RS3, the number of conductions of the transistors T1~T3 can be determined, thereby determining the on-resistance value R _T of the resistance control circuit 102. That is, the on-resistance value R _T of the resistance control circuit 102 can be a resistance value. _RT1 , resistance value _RT2 , resistance value _RT3 , or any combination thereof. Therefore, _{the total} on-resistance value R total of the scan switch circuit 10_1 is the on-resistance value R _C plus the resistance value _RT1 , the resistance value _RT2 , the resistance value _RT3 or any combination thereof.

The scan switch circuit 10_1 in FIG. 2C is similar to the scan switch circuit 10_1 in FIG. 2B, so the differences will be described below.

In FIG. 2C , the resistance control circuit 102 not only includes transistors T1 ~ T3 connected in parallel with each other, but also includes resistors R1 ~ R3. The resistors R1 ~ R3 are coupled in series to the transistors T1 ~ T3 respectively, and have different resistance values. In this embodiment, the on-resistance value R _T1 is the sum of the on-resistance value of the transistor T1 and the resistance value of the resistor R1 , and the on-resistance value R _T2 is the on-resistance value of the transistor T2 and the resistance of the resistor R2 The on-resistance value _RT3 is the sum of the on-resistance value of the transistor T3 and the resistance value of the resistor R3.

In operation, the resistance control circuit 102 of FIG. 2C is similar to the resistance control circuit 102 of FIG. 2B. The transistors T1 - T3 are selectively turned on according to the resistance control signals RS1 - RS3 from the timing control circuit 14 respectively, so that the resistance control circuit 102 provides different on-resistance values R _T . Therefore, the total on-resistance value R _total of the scan switch circuit 10_1 in Figure 2C is the on-resistance value R _C plus the resistance value _RT1 , the resistance value _RT2 , the resistance value _RT3 or any combination thereof.

For example, Figure 3 is a chart of the total on-resistance R _total of the scan switch circuit 10_1 according to some embodiments, wherein Figure 3 can be used to illustrate the total on-resistance R total of the embodiment of Figure 2B or 2C Various setting methods for resistance R _total . The enable level (i.e. 1) of the resistance control signals RS1~RS3 respectively represents that the transistors T1~T3 are conducting, and the disabling level (i.e. 0) represents that the transistors T1~T3 are not conducting respectively. In the embodiment of FIG. 3 , the on-resistance R _C of the switch circuit 100 is 50 milliohms (mΩ), the on-resistance R _T1 of the transistor T1 is 50 mΩ, and the on-resistance R T2 of the transistor _T2 is 100mΩ, and the on-resistance value RT3 of transistor _T3 is 150mΩ. By controlling the resistance control signals RS1 to RS3 to be at the enable level or the disable level, the conduction status of the transistors T1 to T3 can be controlled respectively, so that the resistance control circuit 102 provides different conduction resistance values R _T , thereby enabling The scanning switch circuit 10_1 provides different on-resistance values R _total . However, in the resistance control circuit 102 of Figures 2B to 2C, if the transistors T1 to T3 are not conductive, the resistance control circuit 102 will become open circuit. Therefore, there are a total of 2 ³ -1 (ie, 7) combinations of conduction conditions of the transistors T1 to T3, corresponding to 7 different conduction resistance values R _T and the total conduction resistance value R _total respectively.

Therefore, through the structure of the scan driving circuit 10 in FIGS. 2A to 2C, the total on-resistance value R _total of the scan switch circuit 10_1 can be controlled, and the total on-resistance value R _total can be controlled according to the number of pixel units in each column. adjustment. When the number of pixel units coupled to the scan lines SL[1]~SL[M] is greater (that is, the load of the scan line is greater), the resistance control signals RS1~RS3 can be controlled to reduce the coupling to the scan lines SL[1 _{The total} on-resistance value R total of the scanning switch circuits 10_1~10_M of ]~SL[M]. On the contrary, when the number of pixel units coupled to the scan lines SL[1]~SL[M] is smaller (that is, the load of the scan line is smaller), the resistance control signals RS1~RS3 can be controlled to improve the coupling to the scan lines. _{The total on-resistance value R total} of the scanning switch circuits 10_1~10_M of SL[1]~SL[M]. For example, as shown in Figure 1, the loads of the scan lines SL[1]~SL[M] decrease in sequence, so the total on-resistance value R _total of the scan switch circuits 10_1~10_M can be set to decrease in sequence. Through this control method, it can be ensured that the pixel units P[11]~P[M1] can have approximately the same brightness stabilization time, thereby making the brightness uniform.

Figures 4A to 4C are circuit schematic diagrams of the scan switch circuit 10_1 according to some embodiments. In FIG. 4A , the scan switch circuit 10_1 includes a switch circuit 100 and a resistance control circuit 102 . The switch circuit 100 is coupled to the scan line SL[1] and has an on-resistance value R _C (shown in FIG. 5 ) for selectively conducting according to the switch signal SS from the timing control circuit 14 to switch from the scan line SL to the scan line SL[1]. [1] Receive current. In detail, the switch circuit 100 includes a transistor TS, which is coupled to the scan line SL[1] and is connected in parallel to the resistance control circuit 102 for selectively conducting according to the switch signal SS. The resistance control circuit 102 includes a variable resistor VR and is coupled in parallel to the switch circuit 100 to receive current to adjust the resistance value of the variable resistor VR according to the resistance control signal RS from the timing control circuit 14. The resistance control circuit 102 has a conductor. The on-resistance value _RT (shown in Figure 5), in this embodiment, the on-resistance value _RT is the resistance value of the variable resistor VR. Therefore, the reciprocal of the total on-resistance value R _total of the scan switch circuit 10_1 is the sum of the reciprocal of the on-resistance value R _C and the reciprocal of the on-resistance value _RT .

The scan switch circuit 10_1 in FIG. 4B is similar to the scan switch circuit 10_1 in FIG. 4A, so the differences will be described below.

In FIG. 4B , the resistance control circuit 102 has transistors T1 - T3 connected in parallel with each other, and the transistors T1 - T3 are coupled in parallel to the switch circuit 100 to receive current. The transistor T1 has an on-resistance value R _T1 (shown in FIG. 5 ) for selectively conducting according to the resistance control signal RS1 from the timing control circuit 14 . The transistor T2 has an on-resistance value R _T2 (shown in FIG. 5 ) for selectively conducting according to the resistance control signal RS2 from the timing control circuit 14 . The transistor T3 has an on-resistance value R _T3 (shown in FIG. 5 ) for selectively conducting according to the resistance control signal RS3 from the timing control circuit 14 . According to the resistance control signals RS1~RS3, the number of conductions of the transistors T1~T3 can be determined, thereby determining the on-resistance value R _T of the resistance control circuit 102. That is, the on-resistance value R _T of the resistance control circuit 102 can be a resistance value. _RT1 , resistance value _RT2 , resistance value _RT3 , or any combination thereof. Therefore, the reciprocal of _{the total} on-resistance value R total of the scan switch circuit 10_1 is the reciprocal of the on-resistance value R _C plus the reciprocal of the resistance value R _T1 , the reciprocal of the resistance value R _T2 , the reciprocal of the resistance value R _T3 , or any of them. combination.

The scan switch circuit 10_1 in FIG. 4C is similar to the scan switch circuit 10_1 in FIG. 4B, so the differences will be described below.

In FIG. 4C , the resistance control circuit 102 not only includes transistors T1 ~ T3 connected in parallel with each other, but also includes resistors R1 ~ R3. The resistors R1 ~ R3 are coupled in series to the transistors T1 ~ T3 respectively, and have different resistance values. In this embodiment, the on-resistance value R _T1 is the sum of the on-resistance value of the transistor T1 and the resistance value of the resistor R1 , and the on-resistance value R _T2 is the on-resistance value of the transistor T2 and the resistance of the resistor R2 The on-resistance value _RT3 is the sum of the on-resistance value of the transistor T3 and the resistance value of the resistor R3.

In operation, the resistance control circuit 102 of FIG. 4C is similar to the resistance control circuit 102 of FIG. 4B. The transistors T1 - T3 are selectively turned on according to the resistance control signals RS1 - RS3 from the timing control circuit 14 respectively, so that the resistance control circuit 102 provides different on-resistance values R _T . Therefore, the reciprocal of the _total on-resistance value R total of the scan switch circuit 10_1 in FIG. 4C is the reciprocal of the on-resistance value R _C plus the reciprocal of the resistance value R _T1 , the reciprocal of the resistance value R _T2 , and the reciprocal of the resistance value R _T3 reciprocal or any combination thereof.

For example, Figure 5 is a chart of the total on-resistance value R _total of the scan switch circuit 10_1 according to some embodiments, wherein Figure 5 can be used to illustrate the total on-resistance value of the embodiment of Figure 4B or 4C Various setting methods for resistance R _total . The enable level (i.e. 1) of the resistance control signals RS1~RS3 respectively represents that the transistors T1~T3 are conducting, and the disabling level (i.e. 0) represents that the transistors T1~T3 are not conducting respectively. In the embodiment of FIG. 5 , the on-resistance R _C of the switching circuit 100 is 200 milliohms (mΩ), the on-resistance R _T1 of the transistor T1 is 200 mΩ, and the on-resistance R T2 of the transistor _T2 is 400mΩ, and the on-resistance value RT3 of transistor _T3 is 600mΩ. By controlling the resistance control signals RS1 to RS3 to be at the enable level or the disable level, the conduction status of the transistors T1 to T3 can be controlled respectively, so that the resistance control circuit 102 provides different conduction resistance values R _T , thereby enabling The scanning switch circuit 10_1 provides different on-resistance values R _total . Therefore, there are a total of 2 ³ (ie 8) combinations of conduction conditions of the transistors T1 to T3, corresponding to 8 different conduction resistance values R _T and the total conduction resistance value R _total respectively.

Therefore, through the structure of the scan driving circuit 10 in FIGS. 4A to 4C, the total on-resistance value R _total of the scan switch circuit 10_1 can also be controlled, and the total on-resistance value R total can be controlled according to the number of pixel units in each column. _total adjustment.

In some embodiments, the on-resistance value _RT3 is greater than the on-resistance value _RT2 , and the on-resistance value _RT2 is greater than the on-resistance value _RT1 . In some embodiments, the equivalent on-resistance value formed by the parallel connection of the transistor T3 and the transistor T2 (or the combination of the transistor T3 and the resistor R3 in parallel with the combination of the transistor T2 and the resistor R2) is greater than that of the transistor T1 (or the combination of the transistor T3 and the resistor R2). The on-resistance value R _T1 of the combination of crystal T1 and resistor R1).

Figure 6 is a timing diagram of resistance control signals RS1~RS3 according to some embodiments. In Figure 6, at the rising edge of each line feed signal BS, the resistance control signals RS1~RS3 can be switched between the enable level (ie 1) and the disable level (ie 0).

Taking the chart in Figure 3 as an example, during period P1, the scan driving circuit 10 will select the scan line SL[1] and set the levels of the resistance control signals RS1~RS3 to [0,1,0] (that is, respectively disabling level, enabling level and disabling level, and so on below), so the total on-resistance R _total of the scanning switch circuit 10_1 at this time is 150mΩ. During the period P2, the scan driver circuit 10 will select the scan line SL[2] and set the levels of the resistance control signals RS1~RS3 to [1,0,0]. Therefore, the total on-resistance value of the scan switch circuit 10_2 at this time is R _total is 100mΩ. During the period P3, the scan driver circuit 10 will select the scan line SL[3] and set the levels of the resistance control signals RS1~RS3 to [1,1,1]. Therefore, the total on-resistance value of the scan switch circuit 10_3 at this time is R _total is 77.27mΩ. By analogy, in one frame, the operation of the scan driving circuit 10 may include a total of M periods. In each period, the scan driver circuit 10 selects one of the scan lines SL[1]~SL[M] and sets the resistance control signals RS1~RS3 to the enable level or disable level to control the scan switch circuit. 10_1~10_M corresponds to the total on-resistance value R _total of one.

Taking the chart in Figure 5 as an example, during period P1, the scan driving circuit 10 will select the scan line SL[1] and set the levels of the resistance control signals RS1~RS3 to [0,1,0], so the scan at this time The total on-resistance value R _total of the switching circuit 10_1 is 133.3mΩ. During the period P2, the scan driver circuit 10 will select the scan line SL[2] and set the levels of the resistance control signals RS1~RS3 to [1,0,0]. Therefore, the total on-resistance value of the scan switch circuit 10_2 at this time is R _total is 100mΩ. During the period P3, the scan driver circuit 10 will select the scan line SL[3] and set the levels of the resistance control signals RS1~RS3 to [1,1,1]. Therefore, the total on-resistance value of the scan switch circuit 10_3 at this time is R _total is 70.59mΩ. By analogy, in each period, the scan driving circuit 10 will select one of the scan lines SL[1]~SL[M], and set the resistance control signals RS1~RS3 to the enable level or disable level, so as to The total on-resistance value R _total of the corresponding one of the scanning switch circuits 10_1~10_M is controlled.

It should be noted that the numbers of transistors, resistors and resistance control signals in this disclosure are only examples and do not limit this disclosure. Other quantities of transistors, resistors, and resistor control signals are within the scope of this disclosure. In fact, the greater the number of transistors and resistance control signals, the more various total on-resistance values R _total of the scanning switch circuit can be displayed.

Figure 7 is a flowchart of a control method 700 according to some embodiments. The control method 700 can be used in the scan driving circuit 10 of the present disclosure, wherein the control method 700 includes steps 710 and 720 .

In step 710, at least one resistance control signal (such as the aforementioned resistance control signal RS or resistance control signals RS1-RS2) is used to control the resistance control circuit 102, so that the resistance control circuit 102 adjusts the resistance of the resistance control circuit 102 according to the at least one resistance control signal. On-resistance value R _T . In step 720, the switch circuit 100 is turned on using the switch signal SS. In some embodiments, steps 710 and 720 may be performed in parallel, or the order of execution may be reversed.

In the control method 700, steps 710 and 720 can be repeated multiple times to sequentially turn on multiple scan switch circuits 10_1~10_M, thereby sequentially driving multiple columns of pixel units P[11]~P[M1]. Therefore, through the control method 700, the total on-resistance value of the scan switch circuits 10_1~10_M can be adaptively adjusted according to the number of pixel units or the load of each column.

Through the scan drive circuit and its control method in this disclosure document, the total on-resistance value of each scan switch circuit can be controlled so that each scan line has a similar or identical load to each other to ensure that the pixel units in multiple columns are at the same point. The potential at bright time is more even, thereby achieving uniform brightness, further improving the display quality of the non-rectangular display device.

1: Display device 10: Scan driving circuit 10_1~10_M: Scan switch circuit 12: Display drive circuit 14: Timing control circuit 100: Switch circuit 102: Resistor control circuit 700: Control method 710, 720: Step BS: Line feed signal DL[1] ~DL[N]: Data line GND: Ground power supply P[11]~P[1N], P[21]~P[2(N-1)], P[M1]: Pixel unit P1~P3: Period R1~R3: Resistor RS, RS1~RS3: Resistor control signal R _C , R _T , R _T1 , R _T2 , R _T3 : On-resistance value R _total : Total on-resistance value SL[1]~SL[M] :Scan line SS: Switch signal T1~T3: Transistor VR: Variable resistor

In order to make the above and other objects, features, advantages and embodiments of the present disclosure more obvious and understandable, the accompanying drawings are described as follows: Figure 1 is a functional block diagram of a display device according to some embodiments; Figures 2A to 2C are circuit schematic diagrams of scan switch circuits according to some embodiments; Figure 3 is a chart of the total on-resistance value of the scanning switch circuit according to some embodiments; Figures 4A to 4C are circuit schematic diagrams of scan switch circuits according to some embodiments; Figure 5 is a chart of total on-resistance values of a scan switch circuit according to some embodiments; Figure 6 is a timing diagram of a resistance control signal according to some embodiments; Figure 7 is a flow chart of a control method according to some embodiments.

Domestic storage information (please note in order of storage institution, date and number) without Overseas storage information (please note in order of storage country, institution, date, and number) without

10_1: Scan switch circuit

100: Switch circuit

102: Resistor control circuit

GND: Ground power supply

RS1~RS3: Resistor control signal

SL[1]: scan line

SS: switch signal

T1~T3,TS: transistor

Claims (9)

A scan driving circuit includes: a plurality of scan switch circuits, respectively coupled to a plurality of columns of pixel units, for sequentially conducting to sequentially drive the plurality of columns of pixel units, wherein each of the plurality of scan switch circuits has a total On-resistance values, and each includes: a switch circuit having an on-resistance value for selectively conducting according to a switch signal to receive a current from one of the plurality of rows of pixel units; and a resistance control circuit , having an on-resistance value, coupled to the switch circuit to receive the current, for adjusting the on-resistance value of the resistance control circuit according to a plurality of resistance control signals, wherein the resistance control circuit includes a plurality of transistors, The plurality of transistors are connected in parallel to receive the plurality of resistance control signals and are selectively turned on according to the plurality of resistance control signals, wherein the total on-resistance value is the on-resistance value of the switching circuit and the on-resistance value of the switching circuit. The sum of the on-resistance values of the resistance control circuit, or the reciprocal of the total on-resistance value, is the sum of the reciprocal of the on-resistance value of the switching circuit and the reciprocal of the on-resistance value of the resistance control circuit. The scan driving circuit of claim 1, wherein the resistance control circuit includes a variable resistor that adjusts the on-resistance value of the resistance control circuit according to the plurality of resistance control signals. The scan driving circuit as claimed in claim 2, wherein the The variable resistor is coupled to the switch circuit in series, and the total on-resistance value is the sum of the on-resistance value of the switch circuit and the on-resistance value of the resistance control circuit. The scan driving circuit of claim 2, wherein the variable resistor is coupled in parallel to the switch circuit, and the reciprocal of the total on-resistance value is the reciprocal of the on-resistance value of the switch circuit and the resistance control circuit The sum of the reciprocals of the on-resistance values. The scan driving circuit of claim 1, wherein the plurality of transistors are coupled to the switch circuit in series, and the total on-resistance value is the on-resistance value of the switch circuit and the conduction resistance of the resistance control circuit. The sum of resistance values. The scan driving circuit of claim 5, wherein the resistance control circuit further includes a plurality of resistors, and the plurality of resistors are respectively coupled in series to the plurality of transistors. The scan driving circuit of claim 1, wherein the plurality of transistors are coupled in parallel to the switch circuit, and the reciprocal of the total on-resistance value is the reciprocal of the on-resistance value of the switch circuit and the resistance control The sum of the reciprocals of the on-resistance values of the circuit. The scan driving circuit as claimed in claim 7, wherein the circuit The resistance control circuit further includes a plurality of resistors, and the plurality of resistors are respectively coupled in series to the plurality of transistors. A control method suitable for a scan drive circuit, wherein the scan drive circuit includes a plurality of scan switch circuits, the plurality of scan switch circuits are respectively coupled to a plurality of columns of pixel units, wherein each of the plurality of scan switch circuits has a total On-resistance value, and each includes a switch circuit and a resistance control circuit, wherein the switch circuit and the resistance control circuit each have an on-resistance value, wherein the resistance control circuit includes a plurality of transistors, and the plurality of transistors connected in parallel with each other for receiving a plurality of resistance control signals and selectively conducting according to the plurality of resistance control signals. The control method includes: (a) using the plurality of resistance control signals to control the resistance control circuit so that the resistance control circuit The circuit adjusts the on-resistance value of the resistance control circuit according to the plurality of resistance control signals; (b) uses a switch signal to turn on the switch circuit; and (c) repeats steps (a) and (b) to turn on in sequence The plurality of scanning switch circuits thereby sequentially drive the plurality of columns of pixel units, wherein the total on-resistance value is the sum of the on-resistance value of the switch circuit and the on-resistance value of the resistance control circuit, or The reciprocal of the total on-resistance value is the sum of the reciprocal of the on-resistance value of the switching circuit and the reciprocal of the on-resistance value of the resistance control circuit.

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