TWI543140B - Calibrating circuit and calibrating method for display panel - Google Patents

Description

Correction circuit and correction method of display panel

The present invention relates to a correction circuit, and more particularly to a correction circuit and a correction method for a display panel.

1 is a circuit block diagram illustrating a conventional active matrix organic light emitting diode (AMOLED) display. The AMOLED display includes a gate driver 110, a source driver 120, and a display panel 130. The display panel 130 has a plurality of scanning lines (for example, the scanning lines S_1 and S_2), a plurality of data lines (for example, the data lines D_1 and the data lines D_2), and a plurality of pixel circuits (for example, the pixel circuits 131). The pixel circuit 131 has a switch 132, a driving transistor 133, and an organic LED (OLED) 134.

The gate driver 110 can sequentially scan different scan lines of the display panel 130 to allow the source driver 120 to write data voltages to the pixel circuits. Taking the pixel circuit 131 shown in FIG. 1 as an example, during the period in which the gate driver 110 turns the switch 132 through the scan line S_1, the source driver 120 can transmit the data voltage to the driving power through the data line D_1 and the switch 132. The gate of the crystal 133. The gate voltage of the driving transistor 133 can determine the current I1 of the driving transistor 133. Flowing through the organic light emitting diode 134 The current I1 can determine the brightness of the organic light-emitting diode 134. The relationship between the gate-source voltage of the driving transistor 133 and the current I1 is I1=k(VGS-Vt)2, where the coefficient k is a real number, VGS is the gate-source voltage of the driving transistor 133, and Vt represents the driving transistor. Threshold voltage of 133. Due to process drift or other factors, the valve voltages of the driving transistors in different pixel circuits may differ from each other. Differences/drifts in valve voltage may result in uneven light source (Mura) or other imperfections in the image. If the valve voltage of the driving transistor 133 can be detected, the source driver 120 can adjust the data voltage written in the pixel circuit 131 to compensate for the drift of the valve voltage.

Generally, a compensation circuit is disposed outside the display panel 130 for sensing the valve voltage of the driving transistor 133. The sensed valve voltage is passed through an amplifier and an analog-to-digital converter to obtain a digital code, and the resulting digital code can be used to correct the valve voltage. However, due to process drift or other factors, the gain of the above amplifiers may also be different.

The invention provides a correction circuit and a correction method for a display panel, which can correct the gain of the above amplifier.

Embodiments of the present invention provide a correction circuit for a display panel. The display panel includes a pixel circuit. The pixel circuit includes a driving transistor. The correction circuit includes a pixel sensor, at least one correction sensor, an amplification circuit, and an analog digital converter. And gain adjustment circuit. The input end of the pixel sensor is coupled to the pixel circuit via the data line of the display panel for sensing The terminal voltage of the driving transistor is sensed during the measurement. The input end of the correction sensor is coupled to the first preset voltage and the second preset voltage. The input end of the amplifying circuit is coupled to the pixel sensor and the correction sensor for amplifying the end point voltage according to the gain during the sensing period, and amplifying the first preset voltage and the second pre-preparation according to the gain during the correction period Set the voltage. The input end of the analog-to-digital converter is coupled to the output end of the amplifying circuit for converting the amplified end point voltage into a digit code during sensing, and converting the amplified first preset voltage into the first period during the correction period A digit code converts the amplified second preset voltage into a second digit code. The gain adjustment circuit is coupled to the output end of the analog to digital converter and the amplification circuit for adjusting the gain of the amplification circuit according to the first digital code and the second digital code.

In an embodiment, the gain adjustment circuit includes a first register, a second register, a comparison circuit, and a control circuit. The first register is used to store the first digit code. The second register is for storing the second digit code. The input end of the comparison circuit is coupled to the first register and the second register to calculate a first difference between the first digital code and the second digital code. The control circuit is configured to adjust the gain of the amplifying circuit according to the first difference.

In an embodiment, if the first difference is less than a predetermined threshold, the control circuit is configured to increase the gain of the amplification circuit. If the first difference is greater than the preset threshold, the control circuit is used to reduce the gain of the amplifying circuit.

In an embodiment, after the control circuit adjusts the gain of the amplifying circuit, the amplifying circuit amplifies the first preset voltage and the second preset voltage according to the adjusted gain, and the analog digital converter regenerates the first digital code and the second Digital code. The comparison circuit also calculates the regenerated first digit code The second difference from the regenerated second digit code. If the first difference is less than the preset threshold and the second difference is greater than or equal to the preset threshold, or the first difference is greater than or equal to the preset threshold and the second difference is less than the preset threshold, the control circuit stops adjusting the gain of the amplifying circuit.

In one embodiment, the first predetermined voltage is substantially 25% of the input conversion range of the amplification circuit, and the second predetermined voltage is substantially 75% of the input conversion range.

In an embodiment, the amplifying circuit comprises a switch and an amplifier. The switch is coupled to the pixel sensor and the correction sensor to which the amplifier is coupled. This switch couples the pixel sensor to the amplifier during sensing and couples the correction sensor to the amplifier during calibration. This amplifier includes the following circuits. The first input end and the second input end of the differential amplifier are respectively coupled to the first output end and the second output end of the correction sensor. The first end and the second end of the first capacitor are respectively coupled to the first output end of the correction sensor and the first input end of the differential amplifier. The first end and the second end of the second capacitor are respectively coupled to the second output end of the correction sensor and the second input end of the differential amplifier. Each of the plurality of third capacitance adjustment circuits includes a third capacitance and a first switch. The first end of each of the third capacitors is coupled to the first input end of the differential amplifier, and the second end of each of the third capacitors is coupled to the first end of the first switch, and the second end of each of the first switches The first output is coupled to the differential amplifier. The first end of the fourth capacitor is coupled to the second input of the differential amplifier. The first end and the second end of the second switch are respectively coupled to the first input end of the differential amplifier and the first output end of the differential amplifier. The first end and the second end of the third switch are respectively coupled to the first switch Two-terminal and common-mode voltage. The first end and the second end of the fourth switch are respectively coupled to the second end of the first switch and the first output end of the differential amplifier. The first end and the second end of the fifth switch are respectively coupled to the second input end of the differential amplifier and the second output end of the differential amplifier. The first end and the second end of the sixth switch are respectively coupled to the second end of the fourth capacitor and the common mode voltage. The first end and the second end of the seventh switch are respectively coupled to the second end of the fourth capacitor and the second output end of the differential amplifier. The gain adjustment circuit is configured to control the first switch to adjust the gain of the amplification circuit.

Embodiments of the present invention provide a method of correcting a display panel. The display panel includes a pixel circuit including a drive transistor. The end voltage of the driving transistor is sensed by the pixel sensor during sensing, the output end of the pixel sensor is coupled to the amplifying circuit, and the output end of the amplifying circuit is coupled to the analog digital converter. The calibration method includes: sensing a first preset voltage and a second preset voltage during the correction, and amplifying the first preset voltage and the second preset voltage according to a gain by the amplification circuit; during the calibration by the analog digital converter Converting the first preset voltage into a first digit code, and converting the second preset voltage into a second digit code; and adjusting a gain of the amplifying circuit according to the first digit code and the second digit code.

In an embodiment, the step of adjusting the gain of the amplifying circuit according to the first digit code and the second digit code comprises: calculating a first difference between the first digit code and the second digit code; if the first difference is less than a pre- The threshold value is set to increase the gain of the amplifying circuit; and if the first difference is greater than or equal to the preset threshold value, the gain of the amplifying circuit is reduced.

In an embodiment, the correcting method further includes: after adjusting the gain of the amplifying circuit, the amplifying circuit amplifies the first preset voltage and the second preset voltage according to the adjusted gain, and is regenerated by the analog digital converter. a first digit code and a second digit code; calculating a second difference between the regenerated first digit code and the regenerated second digit code; if the first difference is less than a preset threshold and the second difference is greater than a preset threshold The value, or the first difference is greater than or equal to the preset threshold and the second difference is less than the preset threshold, and the gain of the amplifying circuit is stopped.

The above described features and advantages of the invention will be apparent from the following description.

110‧‧‧gate driver

120‧‧‧Source Driver

130‧‧‧ display panel

131‧‧‧pixel circuit

132‧‧‧ switch

133‧‧‧ drive transistor

134‧‧‧Organic Luminescent Diodes

I1‧‧‧ Current

D_1, D_2‧‧‧ data line

S_1, S_2‧‧‧ scan line

200‧‧‧ display device

210‧‧‧gate driver

220‧‧‧Source Driver

230‧‧‧ display panel

211‧‧‧ mode line

212‧‧‧ scan line

221‧‧‧Information line

231‧‧‧Pixel Circuit

232, 236, 237‧‧ ‧ switch

233‧‧‧Drive transistor

234‧‧‧Lighting diode

235‧‧‧ Capacitance

I2‧‧‧ current

GND‧‧‧ Grounding voltage

VDD‧‧‧ system voltage

300‧‧‧correction circuit

310‧‧‧pixel sensor

320‧‧‧correction sensor

330‧‧‧Amplification circuit

331‧‧‧ switch

332‧‧Amplifier

340‧‧‧ Analog Digital Converter

350‧‧‧Gain adjustment circuit

351, 352‧‧‧ register

353‧‧‧Comparative circuit

354‧‧‧Control circuit

V1‧‧‧ first preset voltage

VCM‧‧‧ Common mode voltage

V2‧‧‧second preset voltage

410, 420, 430‧‧‧ curves

502, 504, 505‧ ‧ switch

503, 503‧‧‧ capacitor

510, 520‧‧‧ Gain Amplifier

VOP‧‧‧ first output

VON‧‧‧second output

VR1‧‧‧ first reference voltage

VR2‧‧‧second reference voltage

610‧‧‧ Third capacitance adjustment circuit

620‧‧‧Differential Amplifier

SW1~SW7‧‧‧ switch

C1~C4‧‧‧ capacitor

VIP_GA‧‧‧ first input

VIN_GA‧‧‧ second input

S701~S703‧‧‧Steps

1 is a circuit block diagram illustrating a conventional active organic light emitting diode display.

2 is a circuit diagram illustrating a display device 200 in accordance with an embodiment of the invention.

FIG. 3 is a block diagram showing a correction circuit 300 according to an embodiment.

4A and 4B are schematic diagrams showing adjustment of gain according to a first difference, according to an embodiment.

FIG. 5 is a circuit diagram showing a correction sensor in accordance with an embodiment.

FIG. 6 is a circuit diagram showing an amplifier 332 according to an embodiment.

FIG. 7 is a flow chart showing a control method of a display panel according to an embodiment.

The term "coupled" as used throughout the specification (including the scope of the patent application) may be used in any direct or indirect connection. For example, if the first device is described as being coupled to the second device, it should be construed that the first device can be directly connected to the second device, or the first device can be connected through other devices or some kind of connection means. Connected to the second device indirectly. In addition, wherever possible, the elements and/ Elements/components/steps that use the same reference numbers or use the same terms in different embodiments may refer to the related description.

2 is a circuit diagram illustrating a display device 200 in accordance with an embodiment of the invention. The display device 200 includes a gate driver 210, a source driver 220, and a display panel 230. The display panel 230 has a plurality of scan lines (or gate lines), a plurality of data lines (or source lines), and a plurality of pixel circuits. Here, the scanning line 212, the data line 221, and the pixel circuit 231 are taken as an example. The pixel circuit 231 has a switch 232, a driving transistor 233, a light emitting diode 234, a storage capacitor 235, a switch 236, and a switch 237. The light emitting diode 234 can be an organic LED (OLED) or other type of light emitting diode.

During the scan, the gate driver 210 can turn off the switch 236 through the mode line 211 and turn on the switch 237. Gate drive during scanning The actuator 210 can also turn on the switch 232 through the scan line 212 to allow the source driver 220 to transmit the data voltage through the data line 221 to the gate of the drive transistor 233. This data voltage can be stored in the storage capacitor 235. The gate voltage of the driving transistor 233 can determine the current I2 that drives the transistor 233. The current I2 flowing through the organic light-emitting diode 234 can determine the brightness of the organic light-emitting diode 234.

During sensing, the gate driver 210 can turn on the switch 236 through the mode line 211 and turn off the switch 237. During sensing, the gate driver 210 can also turn on the switch 232 through the scan line 212, so that the correction circuit (described later) inside the source driver 220 can sense the terminal voltage of the driving transistor 233 through the data line 221 ( In Figure 2 is the valve voltage). After sensing the terminal voltage of the driving transistor 233, the source driver 220 can correspondingly adjust the data voltage to be written to the pixel circuit 231 to compensate for the drift of the valve voltage.

It should be noted that in the embodiment of FIG. 2, the terminal voltage sensed by the source driver 220 is the voltage on the gate (drain) of the driving transistor 233, but in other embodiments the pixel circuit 231 may have different Structure, and this endpoint voltage can also be the source voltage. The present invention does not limit the structure of the pixel circuit 231, nor does it limit the voltage at which end point of the driving transistor 233 is the terminal voltage.

FIG. 3 is a block diagram showing a correction circuit 300 according to an embodiment. Referring to FIGS. 2 and 3 , the correction circuit 300 includes a pixel sensor 310 , at least one correction sensor 320 , an amplification circuit 330 , an analog digital converter 340 , and a gain adjustment circuit 350 . In this embodiment, the amplifying circuit 330 includes a switch 331 and an amplifier 332 , wherein the switch 331 is coupled to the pixel sensor 310 and the correction sensor 320 , and the amplifier 332 is coupled to the switch 331 . The gain adjustment circuit 350 includes a first register 351, a second register 352, a comparison circuit 353, and a control circuit 354.

The input end of the pixel sensor 310 is coupled to the pixel circuit 231 via the data line 221 . The input end of the amplifier circuit 330 is coupled to the pixel sensor 310 and the correction sensor 320 . During sensing, pixel sensor 310 takes the endpoint voltage of drive transistor 232, and switch 331 couples pixel sensor 310 to amplifier 332, which transmits the endpoint voltage and common mode voltage to Amplifier 332, amplifier 332 amplifies the terminal voltage based on a gain. However, it is worth noting that the gain may be greater than or equal to 1 or less than 1, and in this embodiment the gain is about 0.5, but the invention is not limited thereto. The input end of the analog-to-digital converter 340 is coupled to the amplifying circuit 330 for converting the terminal voltage into a digital code during sensing, and the digital code can be used to adjust the data voltage transmitted to the pixel circuit 231. . However, there may be multiple amplifiers 332 in the display device, and different amplifiers 332 may have different gains due to process drift or other factors. Correction sensor 320 and gain adjustment circuit 350 will correct the gain of amplifier 332.

The input end of the correction sensor 320 is coupled to the first preset voltage V1, the common mode voltage VCM, and the second preset voltage V2. During the correction, the switch 331 will couple the correction sensor 320 to the amplifier 332, and the correction sensor 320 will sequentially transmit the first preset voltage V1 and the second preset voltage V2 to the amplifier 332. Specifically, the correction sensor 320 will first pass the first pre- The voltage V1 and the common mode voltage VCM are sent to the amplifier 332, and the amplifier 332 amplifies the first predetermined voltage V1 according to the gain. Then, the analog digital converter 340 converts the amplified first preset voltage V1 into a first digital code, and the first digital code is stored in the first temporary register 351. Next, the correction sensor 320 transmits the second preset voltage V2 and the common mode voltage VCM to the amplifier 332, and the amplifier 332 amplifies the second preset voltage V2 according to the gain. The analog digital converter 340 converts the amplified second preset voltage V2 into a second digital code, and the second digital code is stored in the second temporary register 352.

Since the first preset voltage V1 and the second preset voltage V2 are known, and the gain of the amplifier 332 needs to be fixed at a certain value, the first digit code and the second digit code should be specific values. Based on the first digit code and the second digit code, the gain adjustment circuit 350 can adjust the gain of the amplifier 332. In this embodiment, the comparison circuit 353 calculates the difference between the first digit code and the second digit code (also referred to as the first difference), and the control circuit 354 adjusts the gain of the amplifier 332 based on the first difference.

4A and 4B are schematic diagrams showing adjustment of gain according to a first difference, according to an embodiment. Referring to FIG. 3 and FIG. 4A , the horizontal axis shows the first preset voltage V1 and the second preset voltage V2 , and the vertical axis represents the output of the analog digital converter 340 . Curve 410 represents the conversion curve of ideal amplifier 332, while curve 420 is the actual curve. In this embodiment, the amplifier 332 has an input conversion range of, for example, 4 volts to 8 volts, the first predetermined voltage V1 is 75% of the input conversion range (ie, 7 volts), and the second predetermined voltage V2 is Enter 25% of the conversion range for this (ie 5 volts). The other side The digital code output by the analog-to-digital converter 340 has 10 bits. Therefore, after the amplifier 332 is ideally passed, the first digital code corresponding to the first preset voltage V1 should be 767, and the second preset voltage V2 corresponds to The second digit code should be 256. However, there is an error between the actual curve 420 and the ideal curve 410, so the actual first digit code is actually 750 and the second digit code is 273. Comparison circuit 353 calculates a first difference between the first digit code and the second digit code (i.e., 750-273 = 477). The control circuit 354 determines whether the first difference is less than a preset threshold value, and the preset threshold value is calculated according to the digital code corresponding to the ideal curve 410 (ie, 1024/2=512). If the first difference is less than the preset threshold, it indicates that the gain of the amplifier 332 is too small, so the control circuit 354 increases the gain of the amplifier 332. If the first difference is greater than the preset threshold, it indicates that the gain of the amplifier 332 is too large, so the control circuit 354 reduces the gain of the amplifier 332. In the embodiment of FIG. 4A, the first difference is 477, which is less than the preset threshold 512, so control circuit 354 increases the gain of amplifier 332. After adjusting the gain, referring to FIG. 4B, the amplifier 332 will have a curve 430 that is closer to the ideal curve 410 relative to the curve 420.

In the above embodiment, the first preset voltage V1 is 75% of the input conversion range, the second preset voltage V2 is 25% of the input conversion range, and the preset threshold is 512. However, in other embodiments, the first preset voltage V1 and the second preset voltage V2 may be located in other percentages, so the preset threshold value may be correspondingly other values. It is worth mentioning that the first preset voltage V1 should not be set too high, and the second preset voltage V2 should not be set too low, because the actual curve 420 may not be linear at both ends. In an embodiment, the first preset voltage V1 may be set to be 60% to 90% of the input conversion range, and the second preset voltage may be set to be 10% to 40% of the input conversion range. On the other hand, if the resolution of the digital code output by the analog-to-digital converter 340 has more or fewer bits, the preset threshold value will also change accordingly. In addition, in the above embodiment, the gain correction circuit 350 adjusts the gain of the amplifier 332 according to the difference between the first digital code and the second digital code. However, in other embodiments, the gain correction circuit 350 may also be based on the The ratio between a digital code and a second digital code adjusts the gain of amplifier 332.

Referring back to FIG. 3, in an embodiment, the control circuit 354 adjusts the gain of the amplifier 332 a small amount each time, so the control circuit 354 must determine whether to stop the adjustment or continue. Specifically, after the gain of the amplifier 332 is adjusted according to the first difference, the first preset voltage V1 and the second preset voltage V2 are input to the amplifier 332. The amplifier 332 amplifies the first preset voltage V1 and the second preset voltage V2 according to the adjusted gain, and the analog digital converter 340 regenerates the corresponding first digital code and the second digital code to the first temporary register. 351 and second register 352. Comparison circuit 353 calculates the difference (also known as the second difference) between the regenerated first digital code and the regenerated second digital code. If the first difference is less than the preset threshold and the second difference is greater than the preset threshold (as in the example of FIG. 4A and FIG. 4B), or the first difference is greater than the preset threshold and the second difference is less than the preset threshold Then, the control circuit 354 stops adjusting the gain of the amplifier 332. If the first difference and the second difference are both smaller than the preset threshold or both are greater than the preset threshold, There is still a gap between the gain of amplifier 332 and the ideal gain, so control circuit 354 will continue to adjust the gain of amplifier 332.

FIG. 5 is a circuit diagram showing a correction sensor in accordance with an embodiment. This embodiment has two correction sensors having the same circuit structure, one of which receives the first predetermined voltage V1 and the common mode voltage VCM (as shown in FIG. 5), and the other receives The second preset voltage V2 is a common mode voltage VCM. For the sake of simplicity, only the correction sensor that receives the first preset voltage V1 and the common mode voltage VCM is shown here, and the first preset voltage V1 can be replaced with the second one in the other correction sensor. Set the voltage V2. Referring to FIG. 5, the correction sensor 320 includes switches 502, 504, 505, capacitors 503, 506, and gain amplifiers 510, 520. The first end of the switch 502 is coupled to the first preset voltage V1. The first end of the switch 505 is coupled to the common mode voltage VCM. The first end and the second end of the switch 504 are respectively coupled to the second end of the switch 502 and the second end of the switch 505.

The first end and the second end of the capacitor 503 are respectively coupled to the first reference voltage VR1 and the second end of the switch 502. The first reference voltage VR1 can be a fixed voltage of any level, such as a system voltage, a ground voltage, or other fixed voltage. The first end and the second end of the capacitor 506 are respectively coupled to the second reference voltage VR2 and the second end of the switch 505. The second reference voltage VR2 can be a fixed voltage of any level, such as a system voltage, a ground voltage, or other fixed voltage. The first reference voltage VR1 may be the same or different from the second reference voltage VR2.

The input end of the gain amplifier 510 is coupled to the second end of the switch 502, and the output end of the gain amplifier 510 is the first of the correction sensor 320. Output VOP. The input end of the gain amplifier 520 is coupled to the second end of the switch 505, and the output end of the gain amplifier 520 serves as the second output terminal VON of the correction sensor 320. Gain amplifier 510 and gain amplifier 520 can be any type of amplification circuit. For example, in the present embodiment, the gain amplifier 510 and the gain amplifier 520 may be unit Gain amplifiers.

When the display panel 230 operates during the sensing period, during the first period (first phase) T1 of the sensing period, the switch 502 and the switch 505 are turned on, and the switch 504 is turned off. Therefore, in the first period T1, the output VOP (T1) of the gain amplifier 510 = V1 + Voffset1, and the output of the gain amplifier 520 is VON (T1) = VCM + Voffset2. Wherein, Voffset1 represents the voltage offset of the gain amplifier 510, and Voffset2 represents the voltage offset of the gain amplifier 520. The amplifier 332 can calculate VOP(T1) - VON(T1) = (V1 + Voffset1) - (VCM + Voffset2) in the first period T1. During the second period (second phase) T2 of the sensing period, the switch 502 and the switch 505 are turned off, and the switch 504 is turned on. Therefore, in the second period T2, the output VOP (T2) of the gain amplifier 510 = Vreset + Voffset1, and the output VON (T2) of the gain amplifier 520 = Vreset + Voffset2. Wherein, Vreset indicates the input terminal voltage of the gain amplifier 510 and the gain amplifier 520 when the switch 504 is turned on. The amplifier 332 can calculate VOP(T2) - VON(T2) = Voffset1 - Voffset2 in the second period T2. The amplifier 332 can calculate [VOP(T1) - VON(T1)] - [VOP(T2) - VON(T2)] = V1 - VCM. because Thus, the voltage offset of the gain amplifier 510 and the gain amplifier 520 can be eliminated.

FIG. 6 is a circuit diagram showing an amplifier 332 according to an embodiment. Referring to FIG. 5 and FIG. 6 , the first input terminal VIP_GA of the amplifier 332 is coupled to the first output terminal VOP of the correction sensor 320 , and the second input terminal VIN_GA of the amplifier 332 is coupled to the correction sensor 320 . The second output is VON. The amplifier 332 includes a first capacitor C1, a second capacitor C2, a plurality of third capacitance adjusting circuits 610, a fourth capacitor C4, a second switch SW2, a third switch SW3, a fourth switch SW4, a fifth switch SW5, and a sixth switch. SW6, seventh switch SW7 and differential amplifier 620. The first input terminal (eg, the inverting input terminal) and the second input terminal (eg, the non-inverting input terminal) of the differential amplifier 620 are respectively coupled to the first input terminal VIP_GA and the second input terminal VIN_GA of the amplifier 332.

The first end and the second end of the first capacitor C1 are respectively coupled to the first input terminal VIP_GA of the amplifier 332 and the first input end of the differential amplifier 620. Each of the third capacitance adjusting circuits 610 includes a third capacitor C3 and a first switch SW1. The first end of each of the third capacitors C3 is coupled to the first input of the differential amplifier 620, and the second end of each of the third capacitors C3 is coupled to the first end of the first switch SW1. A second end of each of the first switches SW1 is coupled to a first output of the differential amplifier 620 (eg, a non-inverting output). The first end and the second end of the second switch SW2 are respectively coupled to the first input end and the first output end of the differential amplifier 620. The first end and the second end of the third switch SW3 are respectively coupled to the second end of the first switch SW1 and the common mode Press VCM. The first end and the second end of the fourth switch SW4 are respectively coupled to the second end of the first switch SW1 and the first output end of the differential amplifier 620.

The first end and the second end of the second capacitor C2 are respectively coupled to the second input terminal VIN_GA of the amplifier 332 and the second input terminal (for example, the non-inverting input terminal) of the differential amplifier 620. The first end of the fourth capacitor C4 is coupled to the second input of the differential amplifier 620. The first end and the second end of the fifth switch SW5 are respectively coupled to the second input end and the second output end of the differential amplifier 620. The first end and the second end of the sixth switch SW6 are respectively coupled to the second end of the fourth capacitor C4 and the common mode voltage VCM. The first end and the second end of the seventh switch SW7 are respectively coupled to the second end of the fourth capacitor C4 and the second output end of the differential amplifier 620 (eg, the reverse output end).

During the first period (first phase) T1 of the sensing period, the second switch SW2, the third switch SW3, the fifth switch SW5, and the sixth switch SW6 are turned on, and the fourth switch SW4 and the seventh switch SW7 are cutoff. During the second period (second phase) T2 of the sensing period, the second switch SW2, the third switch SW3, the fifth switch SW5, and the sixth switch SW6 are turned off, and the fourth switch SW4 and the seventh switch SW7 are turned on. The voltage output by the differential amplifier 620 can be expressed as the following equation (1), where _Voffset represents the voltage offset of the differential amplifier 620, and A represents the gain value of the differential amplifier 620.

It is worth noting that the capacitance value C3 in the equation (1) is provided by the plurality of third capacitors C3, so if more of the first switches SW1 are turned on, it means that more third capacitors C3 are connected in parallel, so The capacitance value C3 in equation (1) will be larger. Conversely, if the first switch SW1 is turned off, it means that the capacitance value C3 in the equation (1) is reduced. Referring to FIG. 3 and FIG. 6, in this embodiment, when the control circuit 354 is to increase the gain of the amplifier 332, the control circuit 354 turns off the at least one first switch SW1. Conversely, when control circuit 354 is to reduce the gain of amplifier 332, control circuit 354 turns on at least one first switch SW1. In other words, the control circuit 354 controls the conduction state of the first switch SW1 to adjust the gain of the amplifier 332.

FIG. 7 is a flow chart showing a control method of a display panel according to an embodiment. Referring to FIG. 7, in step S701, the first preset voltage and the second preset voltage are sensed during the correction, and the first preset voltage and the second preset voltage are amplified by the amplification circuit according to a gain. In step S702, the first predetermined voltage is converted into the first digital code by the analog digital converter during the correction, and the second predetermined voltage is converted into the second digital code. In step S703, the gain of the amplification circuit is adjusted according to the first digital code and the second digital code. However, the steps in Fig. 7 have been described in detail above, and the description of each step will not be repeated here. It should be noted that the steps in FIG. 7 can be implemented as multiple codes or circuits, and the present invention is not limited thereto. In addition, the method of FIG. 7 can be used in conjunction with the above embodiments, or can be used alone.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art, The scope of the present invention is defined by the scope of the appended claims.

221‧‧‧Information line

300‧‧‧correction circuit

310‧‧‧pixel sensor

320‧‧‧correction sensor

330‧‧‧Amplification circuit

331‧‧‧ switch

332‧‧Amplifier

340‧‧‧ Analog Digital Converter

350‧‧‧Gain adjustment circuit

351, 352‧‧‧ register

353‧‧‧Comparative circuit

354‧‧‧Control circuit

V1‧‧‧ first preset voltage

VCM‧‧‧ Common mode voltage

V2‧‧‧second preset voltage

Claims (10)

A correction circuit for a display panel, the display panel includes a pixel circuit, the pixel circuit includes a driving transistor, and the correction circuit includes: a pixel sensor, wherein the input end is coupled to the data line via the data line of the display panel a pixel circuit for sensing an end voltage of the driving transistor during a sensing period; at least one correction sensor having an input coupled to a first predetermined voltage and a second predetermined voltage; a circuit having an input coupled to the pixel sensor and the at least one correction sensor for amplifying the terminal voltage according to a gain during the sensing, and amplifying the first according to the gain during a correction a preset voltage and the second preset voltage; an analog-to-digital converter having an input coupled to the output of the amplifier circuit for converting the amplified terminal voltage into a digital code during the sensing period And converting the amplified first preset voltage into a first digit code during the calibration, converting the amplified second preset voltage into a second digit code; and a gain adjustment circuit coupled to the The analogy Bit converter output terminal of the amplifying circuit for amplifying the gain of the circuit according to the first digit and the second digit code code adjustments. The calibration circuit of claim 1, wherein the gain adjustment circuit comprises: a first register for storing the first digit code; and a second register for storing the second digit a comparison circuit, wherein the input end is coupled to the first temporary register and the second temporary register to calculate a first difference between the first digital code and the second digital code; and a control And a circuit for adjusting the gain of the amplifying circuit according to the first difference. The calibration circuit of claim 2, wherein the control circuit is configured to increase the gain of the amplifying circuit if the first difference is less than a predetermined threshold, if the first difference is greater than the preset threshold The control circuit is for reducing the gain of the amplifying circuit. The calibration circuit of claim 3, after the control circuit adjusts the gain of the amplifying circuit, the amplifying circuit amplifies the first preset voltage and the second preset voltage according to the adjusted gain, And the analog-to-digital converter regenerates the first digit code and the second digit code, and the comparing circuit calculates a second difference between the regenerated first digit code and the regenerated second digit code. If the first difference is less than the preset threshold and the second difference is greater than or equal to the preset threshold, or the first difference is greater than or equal to the preset threshold and the second difference is less than the preset threshold, The control circuit stops adjusting the gain of the amplifying circuit. The calibration circuit of claim 4, wherein the first predetermined voltage is substantially 25% of an input conversion range of the amplification circuit, and the second predetermined voltage is substantially 75 of the input conversion range. %. The calibration circuit of claim 1, wherein the amplifying circuit comprises: a switch coupled to the pixel sensor and the at least one correction sensor; and an amplifier coupled to the switch, wherein The switch couples the pixel sensor to the amplifier during the sensing, and couples the at least one correction sensor to the amplifier during the calibration, the amplifier comprising: a differential amplifier, a first An input terminal and a second input end are respectively coupled to a first output end and a second output end of the at least one correction sensor; a first capacitor coupled to the first end and the second end Connected to the first output end of the at least one correction sensor and the first input end of the differential amplifier; a second capacitor, a first end and a second end are respectively coupled to the at least one a second output end of the correction sensor and the second input end of the differential amplifier; a plurality of third capacitance adjustment circuits, each of the third capacitance adjustment circuits including a third capacitor and a first switch The first end of each of the third capacitors is coupled to the first input end of the differential amplifier, and the second end of each of the third capacitors is coupled to the first end of the first switch, each a second end of the first switch is coupled to the first output end of the differential amplifier; a fourth end of the fourth capacitor is coupled to the second input end of the differential amplifier; a switch having a first end and a second end coupled to the first input end of the differential amplifier and the first output end of the differential amplifier; a third switch having a first end and a second end respectively a plurality of second ends coupled to the first switches and a common mode voltage; a fourth switch having a first end and a second end coupled to the second ends of the first switches and the difference a first output end of the dynamic amplifier; a fifth switch having a first end and a second end coupled to the differential amplifier respectively a second input end and a second output end of the differential amplifier; a sixth switch, wherein the first end and the second end are respectively coupled to the second end of the fourth capacitor and the common mode voltage; and a seventh switch The first end and the second end are respectively coupled to the second end of the fourth capacitor and the second output end of the differential amplifier, The gain adjustment circuit is configured to control the first switches to adjust the gain of the amplification circuit. A method for correcting a display panel, the display panel comprising a pixel circuit, the pixel circuit comprising a driving transistor, an end voltage of the driving transistor being sensed by a pixel sensor during a sensing period, the pixel sensing The output of the amplifier is coupled to an amplifier circuit, and the output of the amplifier is coupled to an analog converter. The calibration method includes: sensing a first preset voltage and a second preset voltage during a calibration period. And the amplification circuit amplifies the first preset voltage and the second preset voltage according to a gain; the analog digital converter converts the first preset voltage into a first digital code during the calibration, and Converting the second predetermined voltage into a second digit code; and adjusting the gain of the amplifying circuit according to the first digit code and the second digit code. The method of claim 7, wherein the step of adjusting the gain of the amplifying circuit according to the first digit code and the second digit code comprises: calculating the first digit code and the second digit code a first difference between the two; if the first difference is less than a predetermined threshold, increasing the gain of the amplifying circuit; If the first difference is greater than or equal to the preset threshold, the gain of the amplifying circuit is reduced. The calibration method of claim 8, further comprising: after adjusting the gain of the amplifying circuit, the amplifying circuit amplifies the first preset voltage and the second preset voltage according to the adjusted gain And regenerating the first digit code and the second digit code by the analog to digital converter; calculating a second difference between the regenerated first digit code and the regenerated second digit code; The first difference is less than the preset threshold and the second difference is greater than the preset threshold, or the first difference is greater than or equal to the preset threshold and the second difference is less than the preset threshold, and the adjustment is stopped. This gain of the amplifier circuit. The calibration method of claim 9, wherein the first predetermined voltage is 25% of an input conversion range of the analog-to-digital converter, and the second predetermined voltage is 75% of the input conversion range.