Voltage compensation circuit, source driving circuit, display and voltage compensation method

Abstract

The application discloses a voltage compensation circuit, a source driving circuit, a display and a voltage compensation method. The voltage compensation circuit can be applied to the display. The voltage compensation circuit collects a first power supply voltage on a power supply line at an OLED display screen end in a black insertion stage after the OLED display screen is turned on, and obtains a reference voltage according to the first power supply voltage. Then, a second power supply voltage on the power supply line is collected when each frame of picture is displayed, and the difference between the reference voltage and the currently obtained second power supply voltage is used to adjust pre-stored initial maximum gamma voltage and initial minimum gamma voltage to obtain target maximum gamma voltage and target minimum gamma voltage. Finally, the obtained target maximum gamma voltage and target minimum gamma voltage are provided to a Gamma circuit, so that the Gamma circuit adjusts a Gamma curve according to the target maximum gamma voltage and the target minimum gamma voltage, thereby adjusting Vdata in real time, and then compensating for IR Drop on the power supply line by adjusting Vdata, and improving screen brightness.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a voltage compensation circuit, a source driving circuit, a display, and a voltage compensation method. Background Technology

[0002] Organic light-emitting diode (OLED) displays are one of the hottest research topics in the field of flat panel displays today. Compared with liquid crystal displays (LCDs), OLED displays have advantages such as low energy consumption, low production cost, self-illumination, wide viewing angle and fast response speed. Currently, OLED displays have begun to replace traditional LCDs in the fields of mobile phones, PDAs, digital cameras and other flat panel displays.

[0003] In OLED displays, the OLED emits light through pixel circuitry. (Reference) Figure 1 , Figure 1 This is a simplified circuit diagram illustrating how a pixel circuit drives an OLED to emit light. During display, the brightness of a pixel in an OLED display is determined by the current I flowing through the OLED. The magnitude of current I primarily depends on the gate-source voltage VGS of the driving transistor TFT. The smaller VGS is, the larger the current I flowing through the driving transistor TFT, and the brighter the pixel. Here, VGS = Vdata - VDD, where Vdata represents the voltage value on the data line Data, and VDD represents the voltage value on the power line ELVDD.

[0004] refer to Figure 2 , Figure 2 This is a schematic diagram of an OLED display. The OLED display includes an OLED display screen 01 and a control circuit 02. The OLED display screen 01 has pixels arranged in a matrix. Figure 2(Not shown in the image) Multiple data lines (Data) and multiple power lines (ELVDD) are connected to the OLED display 01. Each pixel includes an OLED and pixel circuitry. The control circuit 02 mainly includes a source driver IC (SourceDriver IC) 021, a power management IC (PMIC) 022, a clock controller 023, a processor 024, and an ELPMIC 025. The source driver IC 021 provides voltage to the data lines (Data), the PMIC 022 provides voltage to the source driver IC 021, and the ELPMIC 025 provides voltage to the power lines (ELVDD). However, because the ELPMIC 025 is relatively far from the OLED display 01, the power line (ELVDD) between the ELPMIC 025 and the OLED display 01 is quite long. Therefore, the voltage drop (IR Drop) on the power line (ELVDD) causes the VDD reaching the OLED display 01 to be lower than the voltage output by the ELPMIC 025, resulting in a dimmer overall screen brightness. Summary of the Invention

[0005] This application provides a voltage compensation circuit, a source drive circuit, a display, and a voltage compensation method, which can compensate for IR drop on the power line, thereby improving screen brightness.

[0006] In a first aspect, embodiments of this application provide a voltage compensation circuit that can be applied to a display. The display includes an OLED screen and a Gamma circuit. The OLED screen has pixels arranged in a matrix, multiple data lines, and multiple power lines. Each pixel includes an OLED and pixel circuitry. The Gamma circuit is integrated into a source driving circuit, which provides voltage to the data lines. The voltage compensation circuit is connected to the power lines and the Gamma circuit at the OLED screen end. This voltage compensation circuit is used to acquire the first power supply voltage on the power line at the OLED display during the black-out phase after the OLED display is turned on, and obtain a reference voltage based on the first power supply voltage; then, when displaying each frame, it acquires the second power supply voltage on the power line, and adjusts the pre-stored initial maximum gamma voltage and initial minimum gamma voltage based on the difference between the reference voltage and the currently acquired second power supply voltage to obtain the target maximum gamma voltage and target minimum gamma voltage; finally, it provides the obtained target maximum gamma voltage and target minimum gamma voltage to the Gamma circuit, so that the Gamma circuit can adjust the Gamma curve according to the target maximum gamma voltage and target minimum gamma voltage, thereby adjusting Vdata in real time, and thus compensating for IR drop on the power line and improving screen brightness by adjusting Vdata.

[0007] In practical implementation, the source driving circuit is generally equipped with a driving circuit. The Gamma circuit adjusts the Gamma curve according to the target maximum gamma voltage and the target minimum gamma voltage, which can generate grayscale voltage corresponding to the image data. Then the driving circuit can provide the grayscale voltage to the data line of the OLED display to realize the display of the image.

[0008] In practical implementation, the voltage compensation circuit in this application can be integrated into the source drive circuit, or it can be set independently from the source drive circuit, which is not limited here.

[0009] In one possible implementation, the voltage compensation circuit may include a sampling circuit and a processing circuit.

[0010] The sampling circuit is used to collect the first power supply voltage on the power line at the OLED display end at least once during the black-out phase after the OLED display is turned on, and converts each collected first power supply voltage into a first digital signal and sends it to the processing circuit; when displaying each frame, it collects the second power supply voltage on the power line at least once, and converts each collected second power supply voltage into a second digital signal and sends it to the processing circuit.

[0011] For example, the sampling circuit can be an analog-to-digital converter (ADC) circuit. The accuracy of the ADC circuit is configured according to the required compensation accuracy. For example, if the required compensation accuracy is 8 bits, then the accuracy of the ADC circuit can be configured to 8-bit accuracy.

[0012] The processing circuit is used to receive each first digital signal sent by the sampling circuit during the black insertion stage, and obtain and store a reference voltage based on at least one received first digital signal; when displaying each frame, it receives each second digital signal sent by the sampling circuit, and adjusts the pre-stored initial maximum gamma voltage and initial minimum gamma voltage according to the difference between the currently acquired second digital signal and the stored reference voltage to obtain the target maximum gamma voltage and target minimum gamma voltage, and provides the obtained target maximum gamma voltage and target minimum gamma voltage to the Gamma circuit in the OLED display so that the Gamma circuit can adjust the Gamma curve according to the currently acquired target maximum gamma voltage and target minimum gamma voltage.

[0013] For example, the processing circuit can be a digital signal processor (DSP).

[0014] In this embodiment, the obtained target maximum gamma voltage and target minimum gamma voltage are digital signals, suitable for cases where the gamma circuit is a PGamma circuit. The two DAC circuits inside the PGamma circuit can convert the target maximum gamma voltage and target minimum gamma voltage into two analog signals respectively. Thus, the PGamma circuit can adjust the gamma curve according to these two analog signals to generate the grayscale voltage corresponding to the image data.

[0015] Optionally, in this application, the processing circuit can obtain the reference voltage based on one first digital signal or multiple first digital signals, and this is not limited here.

[0016] For example, in order to improve the accuracy of the reference voltage, the reference voltage can be obtained from multiple first digital signals.

[0017] In one possible implementation, the processing circuit can calculate the reference voltage based on the average of the received multiple first digital signals.

[0018] In one example, the processing circuit can first determine whether the difference between the currently acquired second digital signal and the stored reference voltage is greater than a threshold. If the difference between the currently acquired second digital signal and the stored reference voltage is greater than the threshold, the initial maximum gamma voltage and the initial minimum gamma voltage are adjusted according to the difference to obtain the target maximum gamma voltage and the target minimum gamma voltage. For example, VGSP(1) = VGSP(0) - K*(V2 - Vref), VGMP(1) = VMSP(0) - K*(V2 - Vref). Wherein, VGSP(1) represents the target minimum gamma voltage, VGMP(1) represents the target maximum gamma voltage, VGSP(0) represents the initial minimum gamma voltage, VGMP(1) represents the initial maximum gamma voltage, V2 represents the second digital signal, Vref represents the reference voltage, and K represents the adjustment coefficient, which can be pre-stored or input to the processor by other circuits, and is not limited here. For example, K = 0.8 to 1.5.

[0019] This application does not limit the size of the threshold; the threshold can be 0 or greater than 0, and the specific design can be based on the actual product.

[0020] Furthermore, if the difference between the currently acquired second digital signal and the stored reference voltage is less than or equal to the threshold, then the target maximum gamma voltage is equal to the target maximum gamma voltage, and the target minimum gamma voltage is equal to the initial minimum gamma voltage.

[0021] The voltage compensation circuit provided in this application embodiment can indirectly compensate for IR drop on the power line by compensating for the minimum and maximum gamma voltages. Furthermore, the implementation of this application embodiment only requires introducing an ADC and a DSP into the existing source driver circuit, resulting in low cost and no need to occupy display screen area. Moreover, by using a high-precision ADC, fast and high-precision ELVDD compensation can be achieved.

[0022] Secondly, this application also provides a voltage compensation method, which may include the following steps: First, during the black-out phase after the OLED display is turned on, a first power supply voltage is acquired on the power line at the OLED display end, and a reference voltage is obtained based on the first power supply voltage. Then, when displaying each frame, a second power supply voltage is acquired on the power line, and a pre-stored initial maximum gamma voltage and an initial minimum gamma voltage are adjusted based on the difference between the reference voltage and the currently acquired second power supply voltage to obtain a target maximum gamma voltage and a target minimum gamma voltage. Finally, the obtained target maximum gamma voltage and target minimum gamma voltage are provided to the gamma circuit so that the gamma circuit adjusts the gamma curve according to the target maximum gamma voltage and target minimum gamma voltage.

[0023] In one possible design, during the black-out phase after the OLED display is turned on, a first power supply voltage on the power line at the OLED display end is sampled at least once, and each sampled first power supply voltage is converted into a first digital signal. A reference voltage is obtained based on at least one first digital signal and stored. When displaying each frame, a second power supply voltage on the power line is sampled at least once, and each sampled second power supply voltage is converted into a second digital signal. The pre-stored initial maximum gamma voltage and initial minimum gamma voltage are adjusted based on the difference between the currently acquired second digital signal and the stored reference voltage to obtain the target maximum gamma voltage and target minimum gamma voltage.

[0024] Optionally, the reference voltage can be calculated based on the average of multiple first digital signals.

[0025] In one example, it can be first determined whether the difference between the currently acquired second digital signal and the stored reference voltage is greater than a threshold; if the difference between the currently acquired second digital signal and the stored reference voltage is greater than the threshold, the initial maximum gamma voltage and the initial minimum gamma voltage are adjusted according to the difference to obtain the target maximum gamma voltage and the target minimum gamma voltage.

[0026] Furthermore, if the difference between the currently acquired second digital signal and the stored reference voltage is less than or equal to a threshold, then the target maximum gamma voltage is equal to the target maximum gamma voltage, and the target minimum gamma voltage is equal to the initial minimum gamma voltage.

[0027] Thirdly, this application also provides a source driving circuit, including the voltage compensation circuit provided in the first aspect or any embodiment of the first aspect, and a Gamma circuit connected to the voltage compensation circuit. When displaying each frame, the pre-stored initial maximum gamma voltage and initial minimum gamma voltage can be adjusted according to the difference between the second power supply voltage and the reference voltage on the power supply line to obtain a target maximum gamma voltage and a target minimum gamma voltage. The obtained target maximum gamma voltage and target minimum gamma voltage are then provided to the Gamma circuit. The Gamma circuit can adjust the Gamma curve according to the target maximum gamma voltage and target minimum gamma voltage, adjusting Vdata in real time, thereby compensating for IR drop on the power supply line and improving screen display brightness by adjusting Vdata.

[0028] For example, the source driving circuit also includes a driving circuit. The Gamma circuit adjusts the Gamma curve according to the target maximum gamma voltage and the target minimum gamma voltage, which can generate grayscale voltage corresponding to the image data. Then the driving circuit can provide the grayscale voltage to the data line of the OLED display to realize the display of the image.

[0029] Fourthly, this application also provides a display, including an OLED display screen and the source driving circuit provided in the third aspect above, the source driving circuit being used to drive the OLED display screen. The display can be any product or component with display function, such as a mobile phone, tablet computer, television, laptop computer, digital photo frame, or navigator. Implementations of this display can refer to the embodiments of the source driving circuit described above; repeated details will not be elaborated further.

[0030] The technical effects that can be achieved in the third and fourth aspects can be described with reference to the technical effects that can be achieved by any possible design in the first aspect above, and will not be repeated here. Attached Figure Description

[0031] Figure 1 A simplified circuit diagram of a pixel circuit driving an OLED to emit light, provided in an embodiment of this application;

[0032] Figure 2 This is a schematic diagram of the structure of an OLED display provided in an embodiment of this application;

[0033] Figure 3 This is a schematic diagram of the structure of a terminal provided in an embodiment of this application;

[0034] Figure 4 This is a schematic diagram illustrating a set of defined Gamma curves as exemplarily shown in this application;

[0035] Figure 5This is a schematic diagram of the voltage compensation circuit provided in the embodiments of this application applied to a display.

[0036] Figure 6 A schematic flowchart illustrating a voltage compensation method provided in an embodiment of this application;

[0037] Figure 7 This is a schematic diagram of the voltage compensation circuit provided in one embodiment of this application;

[0038] Figure 8 This is a timing diagram corresponding to a display provided in one embodiment of this application;

[0039] Figure 9 This is a schematic diagram of the voltage compensation circuit provided in another embodiment of this application;

[0040] Figure 10 for Figure 9 The diagram shows the voltage compensation circuit performing voltage compensation.

[0041] Figure 11 This is a schematic diagram of a source drive circuit provided in an embodiment of this application.

[0042] Explanation of reference numerals in the attached figures:

[0043] 01-OLED display; 02-Control circuit; 03-Housing; 021-Source driving circuit; 022-PMIC; 023-Clock controller; 024-Processor; 025-ELPMIC; 001-Gamma circuit; 002-Driver circuit; 003-Voltage compensation circuit; 0031-Sampling circuit; 0032-Processing circuit; TFT-Driver transistor; Data-Data line; ELVDD-Power line. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The specific operational methods in the method embodiments can also be applied to the device embodiments or system embodiments. It should be noted that in the description of this application, "at least one" refers to one or more, where "multiple" refers to two or more. Therefore, in the embodiments of this application, "multiple" can also be understood as "at least two". Furthermore, it should be understood that in the description of this application, terms such as "first" and "second" are used only for distinguishing purposes and should not be construed as indicating or implying relative importance, nor as indicating or implying order.

[0045] It should be noted that in the embodiments of this application, "connection" refers to electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components, such as the connection between A and B. Alternatively, it can be a direct connection between A and C, a direct connection between C and B, with A and B connected through C.

[0046] To facilitate understanding of the compensation circuit provided in this application embodiment, its application scenario is first described. This compensation circuit can be applied to terminals, including, for example, watches, mobile phones, tablets, personal digital assistants (PDAs), in-vehicle computers, monitors, and televisions (TVs). This application embodiment does not impose any special limitations on the specific form of the aforementioned terminals. For ease of explanation, the following description uses a mobile phone as an example. Figure 3 As shown, the terminal mainly includes an OLED display screen 01 and a control circuit ( Figure 3 (Not shown in the image) and housing 03, the OLED display 01 and control circuit can be housed inside housing 03.

[0047] See Figure 2 The OLED display 01 has pixels arranged in a matrix. Figure 2 (Not shown in the image) Multiple data lines (Data) and multiple power lines (ELVDD) are connected to the OLED display 01. Each pixel includes an OLED and pixel circuitry. The control circuit 02 mainly includes a source driver circuit 021, a PMIC 022, a clock controller 023, a processor 024, and an ELPMIC 025. The source driver circuit 021 provides voltage to the data lines (Data), the PMIC 022 provides voltage to the source driver circuit 021, and the ELPMIC 025 provides voltage to the power lines (ELVDD). However, because the ELPMIC 025 is relatively far from the OLED display 01, the power line (ELVDD) between the ELPMIC 025 and the OLED display 01 is quite long. Therefore, the voltage drop across the power line (ELVDD) results in a lower VDD reaching the OLED display 01 than the output from the ELPMIC 025, leading to a dimmer overall screen brightness.

[0048] In view of this, this application proposes a voltage compensation circuit, a driving circuit, a display, and a voltage compensation method that can compensate for the voltage drop across ELVDD. For ease of understanding, the gamma curve will be introduced first.

[0049] The gamma curve is an important parameter characterizing the optical brightness response of an OLED display to electrical signals. Adjusting the gamma curve allows for adjustment of the display's brightness. The gamma curve can represent the correspondence between the voltage value and the grayscale value at each node, or the correspondence between the stored value in the OLED display's register and the grayscale value. Therefore, the voltage value corresponding to each grayscale value in the gamma curve corresponds one-to-one with the stored value in the OLED module's register.

[0050] Figure 4 This is a schematic diagram showing the relationship between various parameters corresponding to the Gamma curve of an OLED display screen provided in an embodiment of this application. For example... Figure 4 As shown, an exemplary set of set Gamma curves is illustrated. Figure 4 The horizontal axis represents the node grayscale value (Gray). Here, for example, the grayscale value Gray is set to 8 bits, meaning there are 256 grayscale values ​​in the Gamma orientation, from 0 to 255. The left vertical axis represents the stored value D in the register. Stored value D represents the initial value of the grayscale value to be adjusted stored in the register, i.e., the image data. Here, stored value D is represented by 10 bits, and its range is 0-1024. The right vertical axis represents the grayscale voltage value Vdata (i.e., the voltage value corresponding to different grayscale values, i.e., the voltage value on the Data line during display). Here, for example, the range of grayscale voltage value Vdata is set to VGSP-VGMP. VGSP represents the low voltage of the Gamma circuit, corresponding to the lowest grayscale voltage, such as the voltage value corresponding to grayscale value 0. VGMP represents the high voltage of the Gamma circuit, corresponding to the highest grayscale voltage, such as the voltage value corresponding to grayscale value 255. Specifically, as shown... Figure 4As shown, for each grayscale value Gray in the Gamma curve, there is a corresponding grayscale voltage value Vdata and a corresponding stored value D in the register. That is, the voltage values ​​at each node in the grayscale voltage value Vdata correspond one-to-one with the stored values ​​at each node in the stored value D. Taking the range of the grayscale voltage value Vdata as VGSP-VGMP and the range of the stored value D as 0-1024 as an example, the Gamma circuit can determine the grayscale voltage value Vdata corresponding to each node stored value D (0-1024) in the register based on VGSP-VGMP, thereby converting the image data into grayscale voltage. This process is called Gamma adjustment. To make the Source Driver IC more flexible, the digital Gamma (PGamma) circuit has become the mainstream implementation scheme for Gamma circuits. The VGMP and VGSP of the PGamma circuit are generated by the two digital signals input to the PGamma circuit and the two digital-to-analog converter (DAC) circuits inside the PGamma circuit, respectively.

[0051] The present application will now be described in further detail with reference to the accompanying drawings.

[0052] See Figure 5 , Figure 5 This is a schematic diagram of a voltage compensation circuit 003 provided in one embodiment of this application. The voltage compensation circuit 003 is applied in a display, which includes an OLED display screen 01, a Gamma circuit 001, and an ELPMIC 025. The OLED display screen 01 has pixels arranged in a matrix. Figure 5 (Not shown in the image) Multiple data lines (Data) and multiple power lines (ELVDD), each pixel includes an OLED and pixel circuitry. A gamma circuit 001 is integrated into a source driver circuit 021, which provides voltage to the data lines (Data). An ELPMIC 025 provides voltage to the power lines (ELVDD). A voltage compensation circuit 003 is connected to the power lines (ELVDD) and the gamma circuit 001 at the OLED display 01. This voltage compensation circuit 003 can perform voltage compensation using methods such as... Figure 6 As shown, the method may include the following steps:

[0053] Step S101: During the black-out phase after the OLED display 01 is turned on, the first power supply voltage on the power line ELVDD at the end of the OLED display 01 is collected, and a reference voltage is obtained based on the first power supply voltage.

[0054] In actual display process, when the OLED display 01 is powered on, there will be a black insertion stage before each frame is displayed normally. During the black insertion stage, the OLED display 01 will display the black insertion image. This stage can be considered as supplying almost no current to the OLED. Therefore, the reference voltage is obtained based on the first power supply voltage on the power line ELVDD at the OLED display 01.

[0055] Step S102: When displaying each frame, acquire the second power supply voltage on the power line ELVDD, and adjust the pre-stored initial maximum gamma voltage and initial minimum gamma voltage according to the difference between the reference voltage and the currently acquired second power supply voltage to obtain the target maximum gamma voltage and target minimum gamma voltage.

[0056] Step S103: The obtained target maximum gamma voltage and target minimum gamma voltage are provided to the Gamma circuit 001 so that the Gamma circuit 001 can adjust the Gamma curve according to the target maximum gamma voltage and target minimum gamma voltage.

[0057] For specific implementation, see Figure 5 The source driving circuit 021 is generally also equipped with a driving circuit 002. The Gamma circuit 001 adjusts the Gamma curve according to the target maximum gamma voltage and the target minimum gamma voltage, which can generate the gray level voltage corresponding to the image data. Then the driving circuit 002 can provide the gray level voltage to the data line of the OLED display screen 01 to realize the display of the image.

[0058] This application embodiment provides a voltage compensation circuit 003, which can adjust the pre-stored initial maximum gamma voltage and initial minimum gamma voltage according to the difference between the second power supply voltage and the reference voltage on the power line ELVDD when displaying each frame, to obtain the target maximum gamma voltage and target minimum gamma voltage. Then, the obtained target maximum gamma voltage and target minimum gamma voltage are provided to the Gamma circuit 001, so that the Gamma circuit 001 adjusts the Gamma curve according to the target maximum gamma voltage and target minimum gamma voltage, thereby adjusting Vdata in real time, and thereby compensating for the IR drop on ELVDD by adjusting Vdata, thus improving the screen brightness.

[0059] In specific implementation, the voltage compensation circuit 003 in this application can be integrated into the source drive circuit 021, or it can be set independently from the source drive circuit 021, which is not limited here.

[0060] In one possible implementation, see Figure 7 The voltage compensation circuit 003 may include a sampling circuit 0031 and a processing circuit 0032.

[0061] The sampling circuit 0031 is used to sample the first power supply voltage on the power line ELVDD at the end of the OLED display 01 at least once during the black-out phase after the OLED display 01 is turned on, and convert each sampled first power supply voltage into a first digital signal and send it to the processing circuit 0032; when displaying each frame, it samples the second power supply voltage on the power line ELVDD at least once, and convert each sampled second power supply voltage into a second digital signal and send it to the processing circuit 0032.

[0062] For example, the sampling circuit 0031 can be an analog-to-digital converter (ADC) circuit. The accuracy of the ADC circuit is configured according to the required compensation accuracy. For example, if the required compensation accuracy is 8 bits, the accuracy of the ADC circuit can be configured to 8-bit accuracy.

[0063] The processing circuit 0032 is used to receive each first digital signal sent by the sampling circuit 0031 during the black-out phase, and obtain and store a reference voltage based on the received first digital signal; when displaying each frame, it receives each second digital signal sent by the sampling circuit 0031, and adjusts the pre-stored initial maximum gamma voltage and initial minimum gamma voltage according to the difference between the currently acquired second digital signal and the stored reference voltage to obtain the target maximum gamma voltage and target minimum gamma voltage, and provides the obtained target maximum gamma voltage and target minimum gamma voltage to the Gamma circuit 001 in the OLED display 01 so that the Gamma circuit 001 performs Gamma curve adjustment according to the currently acquired target maximum gamma voltage and target minimum gamma voltage.

[0064] For example, the processing circuit 0032 may be a digital signal processor (DSP).

[0065] In this embodiment, the obtained target maximum gamma voltage and target minimum gamma voltage are digital signals, applicable to the case where the Gamma circuit 001 is a PGamma circuit 001. The two DAC circuits inside the PGamma circuit 001 can convert the target maximum gamma voltage and target minimum gamma voltage into two analog signals respectively. Thus, the PGamma circuit 001 can adjust the Gamma curve according to the two analog signals to generate the grayscale voltage corresponding to the image data.

[0066] Optionally, in this application, the processing circuit 0032 can obtain the reference voltage based on one first digital signal or multiple first digital signals, which is not limited here.

[0067] For example, in order to improve the accuracy of the reference voltage, the reference voltage can be obtained from multiple first digital signals.

[0068] In one possible implementation, the processing circuit 0032 can calculate the reference voltage based on the average value of the received plurality of first digital signals.

[0069] In one example, the processing circuit 0032 can first determine whether the difference between the currently acquired second digital signal and the stored reference voltage is greater than a threshold. If the difference between the currently acquired second digital signal and the stored reference voltage is greater than the threshold, the initial maximum gamma voltage and the initial minimum gamma voltage are adjusted according to the difference to obtain the target maximum gamma voltage and the target minimum gamma voltage. For example, VGSP(1) = VGSP(0) - K*(V2 - Vref), VGMP(1) = VMSP(0) - K*(V2 - Vref). Wherein, VGSP(1) represents the target minimum gamma voltage, VGMP(1) represents the target maximum gamma voltage, VGSP(0) represents the initial minimum gamma voltage, VGMP(1) represents the initial maximum gamma voltage, V2 represents the second digital signal, Vref represents the reference voltage, and K represents the adjustment coefficient, which can be pre-stored or input to the processor by other circuits, and is not limited here. For example, K = 0.8 to 1.5.

[0070] This application does not limit the size of the threshold; the threshold can be 0 or greater than 0, and the specific design can be based on the actual product.

[0071] Furthermore, if the difference between the currently acquired second digital signal and the stored reference voltage is less than or equal to the threshold, then the target maximum gamma voltage is equal to the target maximum gamma voltage, and the target minimum gamma voltage is equal to the initial minimum gamma voltage.

[0072] Accordingly, embodiments of this application also provide a voltage compensation method, such as... Figure 6 As shown, the voltage compensation method may include the following steps:

[0073] Step S101: During the black-out phase after the OLED display 01 is turned on, the first power supply voltage on the power line ELVDD at the end of the OLED display 01 is collected, and a reference voltage is obtained based on the first power supply voltage.

[0074] For example, during the black-out phase after the OLED display 01 is turned on, the first power supply voltage on the power line ELVDD at the end of the OLED display 01 is collected at least once, and each collected first power supply voltage is converted into a first digital signal. A reference voltage is obtained based on at least one first digital signal and the reference voltage is stored.

[0075] Optionally, the reference voltage can be calculated based on the average of multiple first digital signals.

[0076] Step S102: When displaying each frame, acquire the second power supply voltage on the power line ELVDD, and adjust the pre-stored initial maximum gamma voltage and initial minimum gamma voltage according to the difference between the reference voltage and the currently acquired second power supply voltage to obtain the target maximum gamma voltage and target minimum gamma voltage.

[0077] For example, when displaying each frame, the second power supply voltage on the power line ELVDD is acquired at least once, and each acquired second power supply voltage is converted into a second digital signal. The pre-stored initial maximum gamma voltage and initial minimum gamma voltage are adjusted according to the difference between the currently acquired second digital signal and the stored reference voltage to obtain the target maximum gamma voltage and target minimum gamma voltage.

[0078] In one possible implementation, it can be first determined whether the difference between the currently acquired second digital signal and the stored reference voltage is greater than a threshold; if the difference between the currently acquired second digital signal and the stored reference voltage is greater than the threshold, the initial maximum gamma voltage and the initial minimum gamma voltage are adjusted according to the difference to obtain the target maximum gamma voltage and the target minimum gamma voltage.

[0079] Furthermore, if the difference between the currently acquired second digital signal and the stored reference voltage is less than or equal to a threshold, then the target maximum gamma voltage is equal to the target maximum gamma voltage, and the target minimum gamma voltage is equal to the initial minimum gamma voltage.

[0080] Step S103: The obtained target maximum gamma voltage and target minimum gamma voltage are provided to the Gamma circuit 001 so that the Gamma circuit 001 can adjust the Gamma curve according to the target maximum gamma voltage and target minimum gamma voltage.

[0081] The voltage compensation circuit 003 and voltage compensation method provided in this application are described below with reference to specific embodiments. It should be noted that this embodiment is for better explanation of this application, but does not limit this application.

[0082] See Figure 8 , Figure 8 This is a timing diagram corresponding to a display provided in one embodiment of this application. When the OLED display screen 01 is turned on, the EN-AVC signal is the voltage compensation enable control signal. A high level EN-AVC indicates that voltage compensation is required, and a low level EN-AVC indicates that voltage compensation is not required. A high level Mute signal indicates the black insertion stage, and a low level Mute signal indicates the normal screen display stage. (In conjunction with...) Figure 8 , Figure 9This is a schematic diagram of the voltage compensation circuit 003 provided in one embodiment of this application. The implementation of this application consists of two stages: sampling ELVDD when there is no IR drop and a normal compensation stage. The ADC circuit samples the voltage on the power line ELVDD at the OLED display 01 terminal and converts the sampled voltage into a digital signal, which is then sent to the DSP for processing.

[0083] refer to Figure 10 , Figure 10 for Figure 9 The diagram shown illustrates the voltage compensation circuit 003 during voltage compensation. Figure 8 The timing diagram shows that after the OLED display 01 is turned on, it checks if EN-AVC equals 1. If EN-AVC = 1, it checks if Mute equals 1. If Mute = 1, the OLED display 01 enters the black-insertion phase, displaying a black-insertion image, during which almost no current is supplied to the OLED. During the black-insertion phase, the ADC circuit acquires the first power supply voltage without IR drop on the power line ELVDD, converts it into a first digital signal, and sends it to the DSP. The DSP obtains a reference voltage based on the received first digital signal and stores it. After the black-insertion image ends, Mute = 0. When displaying each frame, the ADC circuit converts the second power supply voltage with IR drop on the power line ELVDD into a second digital signal and sends it to the DSP. The DSP determines if the difference between the currently acquired second digital signal and the stored reference voltage is greater than a threshold. If the difference is greater than the threshold, the initial maximum gamma voltage and the initial minimum gamma voltage are adjusted according to the difference to obtain the target maximum gamma voltage and the target minimum gamma voltage. If the difference between the currently acquired second digital signal and the stored reference voltage is less than or equal to the threshold, then the target maximum gamma voltage is equal to the target maximum gamma voltage, and the target minimum gamma voltage is equal to the initial minimum gamma voltage. Finally, the DSP provides the obtained target maximum and target minimum gamma voltages to the PGamma circuit 001. The two DAC circuits inside the PGamma circuit 001 can convert the target maximum and target minimum gamma voltages into two analog signals respectively. Therefore, the PGamma circuit 001 can adjust the gamma curve according to these two analog signals to generate the grayscale voltage corresponding to the image data.

[0084] The voltage compensation circuit 003 provided in this application embodiment can indirectly compensate for the IR drop on the power line ELVDD by compensating for the minimum and maximum gamma voltages. Furthermore, the implementation of this application embodiment only requires introducing an ADC and a DSP on top of the existing source drive circuit 021, resulting in low cost and no need to occupy display screen area. Moreover, by using a high-precision ADC, fast and high-precision ELVDD compensation can be achieved.

[0085] Accordingly, see Figure 11 This application also provides a source drive circuit 021, including any of the voltage compensation circuits 003 described in the embodiments of this application and a Gamma circuit 001 connected to the voltage compensation circuit 003. When displaying each frame, the pre-stored initial maximum gamma voltage and initial minimum gamma voltage can be adjusted according to the difference between the second power supply voltage and the reference voltage on the power line ELVDD to obtain a target maximum gamma voltage and a target minimum gamma voltage. The obtained target maximum gamma voltage and target minimum gamma voltage are then provided to the Gamma circuit 001. The Gamma circuit 001 can adjust the Gamma curve according to the target maximum gamma voltage and target minimum gamma voltage, adjusting Vdata in real time, thereby compensating for the IR drop on the power line ELVDD and improving screen display brightness by adjusting Vdata.

[0086] See also Figure 11 The source driving circuit 021 also includes a driving circuit 002. The Gamma circuit 001 adjusts the Gamma curve according to the target maximum gamma voltage and the target minimum gamma voltage, which can generate grayscale voltage corresponding to the image data. Then, the driving circuit 002 can provide the grayscale voltage to the data line of the OLED display screen 01 to realize the display of the image.

[0087] Accordingly, this application also provides a display, including an OLED display screen 01 and a source driving circuit 021 provided in the embodiments of this application, the source driving circuit 021 being used to drive the OLED display screen 01. The structure of this display can be found in [reference needed]. Figure 5 The display can be any product or component with a display function, such as a mobile phone, tablet computer, television, laptop computer, digital photo frame, or navigator. Implementation of this display can be found in the embodiment of the source driver circuit 021 described above; details will not be repeated.

[0088] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A voltage compensation circuit, characterized in that, The voltage compensation circuit is used in a display, which includes an OLED display screen and a gamma circuit; the voltage compensation circuit is used for: During the blackout phase after the OLED display is turned on, the first power supply voltage on the power line at the OLED display end is collected, and a reference voltage is obtained based on the first power supply voltage. When displaying each frame, the second power supply voltage on the power line is acquired, and the pre-stored initial maximum gamma voltage and initial minimum gamma voltage are adjusted according to the difference between the reference voltage and the currently acquired second power supply voltage to obtain the target maximum gamma voltage and target minimum gamma voltage. The obtained target maximum gamma voltage and target minimum gamma voltage are provided to the gamma circuit so that the gamma circuit can adjust the gamma curve according to the target maximum gamma voltage and target minimum gamma voltage.

2. The voltage compensation circuit as described in claim 1, characterized in that, The voltage compensation circuit includes: a sampling circuit and a processing circuit; The sampling circuit is used to collect the first power supply voltage on the power line at the OLED display end at least once during the black-out phase after the OLED display is turned on, and converts each collected first power supply voltage into a first digital signal and sends it to the processing circuit; and collects the second power supply voltage on the power line at least once when displaying each frame, and converts each collected second power supply voltage into a second digital signal and sends it to the processing circuit. The processing circuit is used to receive each of the first digital signals sent by the sampling circuit during the black-out phase, and obtain a reference voltage based on at least one of the received first digital signals and store the reference voltage; when displaying each frame, it receives each of the second digital signals sent by the sampling circuit, and adjusts the pre-stored initial maximum gamma voltage and initial minimum gamma voltage according to the difference between the currently acquired second digital signal and the stored reference voltage to obtain the target maximum gamma voltage and target minimum gamma voltage, and provides the obtained target maximum gamma voltage and target minimum gamma voltage to the gamma circuit in the OLED display so that the gamma circuit can perform gamma curve adjustment according to the currently acquired target maximum gamma voltage and target minimum gamma voltage.

3. The voltage compensation circuit as described in claim 2, characterized in that, The processing circuit is used to obtain a reference voltage based on the received plurality of first digital signals, including: The processing circuit is used to obtain the reference voltage based on the average value of the received plurality of first digital signals.

4. The voltage compensation circuit as described in claim 2 or 3, characterized in that, The processing circuit is used to adjust the pre-stored initial maximum gamma voltage and initial minimum gamma voltage according to the difference between the currently acquired second digital signal and the stored reference voltage, to obtain the target maximum gamma voltage and target minimum gamma voltage, including: Determine whether the difference between the currently acquired second digital signal and the stored reference voltage is greater than a threshold. If the difference between the currently acquired second digital signal and the stored reference voltage is greater than the threshold, the initial maximum gamma voltage and the initial minimum gamma voltage are adjusted according to the difference to obtain the target maximum gamma voltage and the target minimum gamma voltage.

5. The voltage compensation circuit as described in claim 4, characterized in that, The processing circuit is also used for: If the difference between the currently acquired second digital signal and the stored reference voltage is less than or equal to the threshold, then the target maximum gamma voltage is equal to the target maximum gamma voltage, and the target minimum gamma voltage is equal to the initial minimum gamma voltage.

6. A source driving circuit, characterized in that, It includes the voltage compensation circuit as described in any one of claims 1-5 and the gamma circuit connected to the voltage compensation circuit.

7. A display, characterized in that, It includes an OLED display and a source driving circuit as described in claim 6, the driving circuit being used to drive the OLED display.

8. A voltage compensation method, characterized in that, include: During the black-out phase after the OLED display is turned on, the first power supply voltage on the power line at the OLED display end is collected, and a reference voltage is obtained based on the first power supply voltage. When displaying each frame, the second power supply voltage on the power line is acquired, and the pre-stored initial maximum gamma voltage and initial minimum gamma voltage are adjusted according to the difference between the reference voltage and the currently acquired second power supply voltage to obtain the target maximum gamma voltage and target minimum gamma voltage. The obtained target maximum gamma voltage and target minimum gamma voltage are provided to the gamma circuit so that the gamma circuit adjusts the gamma curve according to the target maximum gamma voltage and target minimum gamma voltage.

9. The voltage compensation method as described in claim 8, characterized in that, During the black-out phase after the OLED display is turned on, the first power supply voltage on the power line at the OLED display end is collected, and a reference voltage is obtained based on the first power supply voltage, including: During the black-out phase after the OLED display is turned on, the first power supply voltage on the power line at the OLED display end is collected at least once, and each collected first power supply voltage is converted into a first digital signal. A reference voltage is obtained based on at least one first digital signal and the reference voltage is stored. When displaying each frame, the second power supply voltage on the power line is acquired, and the pre-stored initial maximum gamma voltage and initial minimum gamma voltage are adjusted according to the difference between the reference voltage and the currently acquired second power supply voltage to obtain the target maximum gamma voltage and target minimum gamma voltage, including: When displaying each frame, the second power supply voltage on the power line is acquired at least once, and each acquired second power supply voltage is converted into a second digital signal. The pre-stored initial maximum gamma voltage and initial minimum gamma voltage are adjusted according to the difference between the currently acquired second digital signal and the stored reference voltage to obtain the target maximum gamma voltage and target minimum gamma voltage.

10. The voltage compensation method as described in claim 9, characterized in that, Obtaining a reference voltage based on a plurality of the first digital signals includes: The reference voltage is obtained based on the average value of multiple first digital signals.

11. The voltage compensation method as described in claim 9 or 10, characterized in that, Adjusting the pre-stored initial maximum gamma voltage and initial minimum gamma voltage based on the difference between the currently acquired second digital signal and the stored reference voltage, to obtain the target maximum gamma voltage and target minimum gamma voltage, including: Determine whether the difference between the currently acquired second digital signal and the stored reference voltage is greater than a threshold. If the difference is greater than the threshold, the initial maximum gamma voltage and the initial minimum gamma voltage are adjusted according to the difference to obtain the target maximum gamma voltage and the target minimum gamma voltage.

12. The voltage compensation method as described in claim 11, characterized in that, Also includes: If the difference is less than or equal to the threshold, then the target maximum gamma voltage is equal to the target maximum gamma voltage, and the target minimum gamma voltage is equal to the initial minimum gamma voltage.

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