Organic Light-Emitting Display and Compensation Method Thereof

Abstract

The present application discloses an organic light-emitting display and a compensation method therefor. The compensation method of the organic light-emitting display includes the steps of: obtaining a first threshold voltage and a second threshold voltage of a driving switch; calculating an average value of all the first threshold voltages to obtain a first average value, and calculating an average value of all the second threshold voltages to obtain a second average value; calculating a compensation value by using the first threshold voltage, the second threshold voltage, the first average value, and the second average value through a compensation formula; combining the compensation value into a data driving voltage to drive the corresponding driving switch, and compensating for the uniformity and mobility of the driving switch. Through the above compensation method, the problem of uneven display caused by mobility differences and threshold voltage drift of the driving switch during display can be solved, so that the output currents of the driving transistors of each pixel unit tend to be consistent, the uniformity of the display brightness is ensured, and thus the display image quality is improved.

Description

Technical Field

[0001] This application relates to the field of display technologies, and particularly to an organic light emitting display and a compensation method therefor. Background Art

[0002] The organic light emitting elements used in an organic light emitting diode (OLED) are self-luminous elements having a light emitting layer between two electrodes. The organic light emitting elements receive electrons and holes from a cathode serving as an electron injection electrode and an anode serving as a hole injection electrode, and inject the electrons and holes into the light emitting layer. The injected electrons and holes recombine to form excitons, and when the excitons drop from the excited state to the ground state, the organic light emitting elements emit light.

[0003] However, during the display process of the organic light emitting display, due to the mobility differences of the driving switches and the threshold voltage drift caused by factors such as manufacturing process or aging, the current flowing through the organic light emitting elements changes, resulting in uneven display. Summary of the Invention

[0004] The purpose of this application is to provide an organic light emitting display and a compensation method therefor to improve the display problems of the organic light emitting display caused by the threshold voltage drift of the driving switches and the electron mobility differences during display.

[0005] This application discloses a compensation method for an organic light emitting display, including the steps of:

[0006] Obtaining a first threshold voltage and a second threshold voltage of a driving switch;

[0007] Calculating the average value of all the first threshold voltages to obtain a first average value, and calculating the average value of all the second threshold voltages to obtain a second average value;

[0008] Calculating a compensation value by using the first threshold voltage, the second threshold voltage, the first average value and the second average value through a compensation formula; and

[0009] Combining the compensation value into a data driving voltage to drive the corresponding driving switch to compensate the uniformity and mobility of the driving switch;

[0010] Among them, in the step of calculating the compensation value by using the first threshold voltage, the second threshold voltage, the first average value, and the second average value through the compensation formula, the first threshold voltage and the first average value are respectively substituted into the uniformity compensation formula to calculate the uniformity compensation value, and the second threshold voltage and the second average value are substituted into the mobility compensation formula to calculate the mobility compensation value; subsequently, the uniformity compensation value and the mobility compensation value are respectively combined into the data driving voltage to drive the corresponding driving switch, and the uniformity and mobility of the driving switch are respectively compensated;

[0011] The uniformity compensation formula is: data_Vth = F(s1_data - s1_data_aver), where data_Vth is the uniformity compensation value, s1_data is the first threshold voltage, s1_data_aver is the first average value, and F is the compensation coefficient; the mobility compensation formula is: Data_cu = (1 - s2_data / s2_data_aver) * d_data, where Data_cu is the mobility compensation value, s2_data is the second threshold voltage, s2_data_aver is the second average value, and d_data is the data driving voltage.

[0012] Optionally, F is equal to the ratio of the precision of d_data to the precision of s1_data.

[0013] Optionally, in the step of combining the compensation value into the data driving voltage to drive the corresponding driving switch and compensating the uniformity and mobility of the driving switch, only the uniformity of the driving switch is compensated; or only the mobility of the driving switch is compensated; or the uniformity and mobility of the driving switch are compensated simultaneously.

[0014] Optionally, the uniformity compensation time of the driving switch is greater than the mobility compensation time.

[0015] Optionally, in the step of obtaining the first threshold voltage and the second threshold voltage of the driving switch, the voltage output by the driving switch in the first time period is obtained as the first threshold voltage, and the voltage output by the driving switch in the second time period is obtained as the first threshold voltage, and the time of the first time period is greater than the time of the second time period.

[0016] Optionally, in the step of calculating the average value of all the first threshold voltages to obtain the first average value and calculating the average value of all the second threshold voltages to obtain the second average value, the average value of the first threshold voltages of all the driving switches in the organic light-emitting display is calculated simultaneously to obtain the first average value, and the average value of the second threshold voltages of all the driving switches in the organic light-emitting display is calculated simultaneously to obtain the second average value.

[0017] Optionally, after the step of combining the compensation value into the data driving voltage to drive the corresponding driving switch and compensating the uniformity and mobility of the driving switch, the method further includes:

[0018] detecting whether the uniformity of the driving switch is compensated to a set target;

[0019] If so, storing the uniformity compensation value and the mobility compensation value into the same memory of the organic light emitting display; if not, recalculating the uniformity compensation value and the mobility compensation value.

[0020] Optionally, before the step of obtaining the first threshold voltage and the second threshold voltage of the driving switch, adjusting the working mode of the organic light emitting display to a compensation mode;

[0021] After detecting that the uniformity of the driving switch is compensated to the set target and storing the uniformity compensation value and the mobility compensation value into the memory of the organic light emitting display, the working mode of the organic light emitting display is automatically adjusted to a display mode, and the driving switch is compensated by the uniformity compensation value and / or the mobility compensation value stored in the memory.

[0022] Optionally, before adjusting the working mode of the organic light emitting display to the compensation mode, first detecting whether the uniformity and mobility in the driving switch are abnormal. If abnormal, the organic light emitting display displays a suggestion to enter the compensation mode; if normal, the organic light emitting display works normally.

[0023] The present application also discloses an organic light emitting display, which adopts the compensation method of the above organic light emitting display.

[0024] In the present application, after obtaining the first threshold voltage and the second threshold voltage of the driving switch and calculating the first average value and the second average value respectively, the compensation voltage required for the driving switch can be directly calculated through the compensation formula, thereby solving the problem of uneven display caused by mobility difference and threshold voltage drift of the driving switch in display, making the output currents of the driving transistors of each pixel unit tend to be consistent, ensuring the uniformity of display brightness, and thus improving the display picture quality. Description of the Drawings

[0025] The accompanying drawings included are used to provide a further understanding of the embodiments of the present application, and form a part of the specification, and are used to illustrate the embodiments of the present application and, together with the written description, to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts. In the drawings:

[0026] Figure 1 It is a schematic diagram of an organic light-emitting display provided by an embodiment of the present application;

[0027] Figure 2 It is a flowchart of a compensation method for an organic light-emitting display provided by an embodiment of the present application;

[0028] Figure 3 is based on Figure 2 A flowchart of a method of an embodiment. Specific Embodiments

[0029] It should be understood that the terms, specific structures and functional details disclosed here are only for describing specific embodiments and are representative. However, the present application can be specifically implemented in many alternative forms and should not be construed as being limited only to the embodiments set forth herein.

[0030] In addition, unless otherwise clearly specified and limited, "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, or the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0031] In an organic light-emitting display, the current flowing through the organic light-emitting unit is IOLED = k[VDD - (Vdata - Vth)] 2 , where k is a conversion coefficient related to the mobility of the driving switch, Vth is the threshold voltage of the driving switch. In display, the difference in mobility and the threshold voltage Vth will drift due to factors such as manufacturing process or aging, resulting in changes in IOLED and display unevenness. Based on this, the embodiments of the present application provide an organic light-emitting display and its compensation method to solve the display problems caused by the difference in mobility and the non-uniformity of the threshold voltage Vth.

[0032] Figure 1 It is a schematic diagram of an organic light-emitting display provided by an embodiment of the present application. As Figure 1 shown, an organic light-emitting display provided by an embodiment of the present application includes a plurality of pixel structures located in a display panel and an external compensation circuit located outside the display panel.

[0033] The pixel structure includes an organic light-emitting diode (OLED), a first switch T1, a driving switch T2, a storage capacitor C1, and a sensing switch T3. The first switch T1, the driving switch T2, and the sensing switch T3 are all thin-film transistors. The gate of the first switch T1 is connected to the scan line Scan, the drain of the first switch T1 is connected to the data line Data, and the source of the first switch T1 is connected to the gate of the driving switch T2. The driving switch T2 controls the driving current IOLED flowing into the organic light-emitting diode (OLED) according to its source-gate voltage Vgs. The drain of the driving switch T2 is connected to the high-potential driving voltage VDD, the source of the driving switch T2 is connected to one end of the organic light-emitting diode (OLED), and the other end of the organic light-emitting diode (OLED) is connected to the low-potential driving voltage VSS.

[0034] There is a connection point N1 between the source of the first switch T1 and the gate of the driving switch T2, and there is a connection point N2 between the source of the driving switch T2 and the organic light-emitting diode (OLED). One end of the storage capacitor C1 is connected to N1, and the other end is connected to the high-potential driving voltage VDD. The gate of the sensing switch T3 is commonly connected to the sensing scan line Sense Scan, the drain of the sensing switch T3 is connected to N2, and the source of the sensing switch T3 is connected to the sensing line Sense. It should be noted that the first switch T1, the driving switch T2, and the sensing switch T3 can be N-type transistors or P-type transistors, which are not limited herein.

[0035] The external compensation circuit includes a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), a first switch SW1, a second switch SW2, and a compensation module X. The first switch SW1 conducts the current flow between the input terminal of the initialization voltage Vpre and the sensing line, and senses the threshold voltage of the driving switch T2 through the sensing switch T3. The second switch SW2 conducts the current flow between the sensing line and the ADC. The ADC converts the threshold voltage of the driving switch into a digital value and transmits the threshold voltage in digital state to the compensation module X. The compensation value is calculated through the compensation formula in the compensation module X for the threshold voltage in digital state. The DAC converts the digital compensation value received from the compensation module X into a compensation voltage and outputs the compensation voltage combined with the data driving voltage to the data line to drive the corresponding driving switch.

[0036] Among them, the external compensation circuit can be integrated into the source driver circuit or can be an independent device. It should be noted that Figure 1 the external compensation circuit in

[0037] is a schematic circuit, and the embodiments of the present application are not limited thereto, and other external compensation circuits can also be used. Figure 2As shown, an embodiment of the present application provides a compensation method for an organic light-emitting display, which is used to compensate the uniformity and mobility of driving switches in the above-mentioned organic light-emitting display. The compensation method for the organic light-emitting display includes the following steps:

[0038] S1: Obtain a first threshold voltage and a second threshold voltage of the driving switch;

[0039] S2: Calculate the average value of all the first threshold voltages to obtain a first average value, and calculate the average value of all the second threshold voltages to obtain a second average value;

[0040] S3: Calculate a compensation value by using the first threshold voltage, the second threshold voltage, the first average value, and the second average value through a compensation formula;

[0041] S4: Combine the compensation value into the data driving voltage to drive the corresponding driving switch, and compensate the uniformity and mobility of the driving switch.

[0042] Through the above method, after obtaining the first threshold voltage and the second threshold voltage of the driving switch, and calculating the first average value and the second average value respectively, the voltage required for compensating the driving switch can be directly calculated through the compensation formula, thereby solving the problem of uneven display caused by the mobility difference and threshold voltage drift of the driving switch during display, making the output currents of the driving transistors of each pixel unit tend to be consistent, ensuring the uniformity of display brightness, and thus improving the display image quality.

[0043] In step S1, the threshold voltage of the driving switch T2 is sensed through the sensing switch T3. The specific sensing process has been described above and will not be elaborated here.

[0044] Moreover, in step S1, the voltage output by the driving switch in the first time period is taken as the first threshold voltage, and the voltage output by the driving switch in the second time period is taken as the second threshold voltage, and the time of the first time period is greater than the time of the second time period.

[0045] In step S2, in the steps of calculating the average value of all the first threshold voltages to obtain a first average value and calculating the average value of all the second threshold voltages to obtain a second average value, the average value of the first threshold voltages of all the driving switches in the organic light-emitting display is calculated simultaneously to obtain a first average value, and the average value of the second threshold voltages of all the driving switches in the organic light-emitting display is calculated simultaneously to obtain a second average value. Of course, in order to improve the accuracy, the first threshold voltage of each driving switch can be further obtained multiple times, and finally all the first threshold voltages are averaged to obtain a first average value. Similarly, the second average value is also the same.

[0046] For step S3, the following specific embodiments are provided in the embodiments of the present application for specific description:

[0047] As an implementation manner, in step S3, the first threshold voltage and the first average value are respectively substituted into the uniformity compensation formula to calculate the uniformity compensation value, and the second threshold voltage and the second average value are substituted into the mobility compensation formula to calculate the mobility compensation value; subsequently, the uniformity compensation value and the mobility compensation value are respectively combined into the data driving voltage to drive the corresponding driving switch, and the uniformity and mobility of the driving switch are respectively compensated.

[0048] Among them, the uniformity compensation formula is: data_Vth = F(s1_data - s1_data_aver), where data_Vth is the uniformity compensation value, s1_data is the first threshold voltage, s1_data_aver is the first average value, and F is the compensation coefficient.

[0049] The mobility compensation formula is: Data_cu = (1 - s2_data / s2_data_aver) * d_data, where Data_cu is the mobility compensation value, s2_data is the second threshold voltage, s2_data_aver is the second average value, and d_data is the data driving voltage.

[0050] In this implementation manner, the correlation of F is determined by the precision (resolution) relationship between s1_data and d_data, that is, F is equal to the ratio of the precision of d_data to the precision of s1_data. For example, when the precisions of both s1_data and d_data are 0.1V, then F is 1; for example, when the precision of s1_data is 0.05V and the precision of d_data is 0.1V, then the coefficient F is 2. And so on.

[0051] In this implementation manner, by calculating the uniformity compensation value and the mobility compensation value through the uniformity compensation formula and the mobility compensation formula respectively to compensate the uniformity and mobility of the driving switch respectively, it can be realized that the external compensation circuit only compensates the uniformity of the driving switch, or the external compensation circuit only compensates the mobility of the driving switch, or the external compensation circuit simultaneously compensates the uniformity and mobility of the driving switch; even according to the actually sensed threshold voltage situation, the compensation degrees of the uniformity and mobility are adjusted. Therefore, by adopting the means of this implementation manner, the compensation data can be made more accurate, the compensation effect is better, and the display uniformity effect of the display can be further improved.

[0052] In this implementation manner, when the driving switch is not compensated, the data voltage received by the gate of the driving switch is Vdata; after the driving switch is compensated, the data voltage received by the gate of the driving switch is Vdata + data_Vth + Data_cu.

[0053] Further, the duration of the uniformity compensation value combined with the data driving voltage is greater than the duration of the mobility compensation value combined with the data driving voltage, that is, the uniformity compensation time of the driving switch is greater than the mobility compensation time. Generally, due to the different magnitudes of the uniformity compensation value and the mobility compensation value, the uniformity compensation value and the mobility compensation value are compensated simultaneously through the same data line along with the data driving voltage Vdata, and the voltage received by the gate of the driving switch is the sum of Vdata, the uniformity compensation value, and the mobility compensation value. It is difficult to accurately compensate the uniformity and mobility of the driving switch separately. Therefore, after adopting the above design, the embodiment can accurately compensate the uniformity and mobility of the driving switch by controlling the output time of the uniformity compensation value and the mobility compensation value, improving the compensation effect. In addition, since the value of the uniformity compensation value is generally larger and the data for compensating the threshold voltage of the driving switch is larger, a longer compensation time is required.

[0054] After compensating the uniformity and mobility of the driving switch, the embodiment of the present application also additionally adds a detection step for the compensation effect, specifically referring to the following implementation manner:

[0055] As one of the implementation manners, as Figure 3 shown, after step S4, the steps further include:

[0056] S5: Detect whether the uniformity of the driving switch is compensated to the set target;

[0057] If so, execute step S6: Store the uniformity compensation value and the mobility compensation value in the same memory of the organic light-emitting display;

[0058] If not, return to step S1 to recalculate the uniformity compensation value and the mobility compensation value from the beginning.

[0059] To avoid fluctuations or other abnormal problems in the threshold voltage during the detection process, resulting in inaccurate compensation data, in this embodiment, after calculating the uniformity compensation value and the mobility compensation value, the compensated effect is simulated according to the compensation value to ensure the display effect after compensation.

[0060] Among them, the set target can be determined according to the difference between the maximum value and the minimum value of the threshold voltages of all driving switches in the organic light-emitting display, or can be determined in other ways. Moreover, it should be noted that after detecting that the uniformity of the driving switch is compensated, it can be directly concluded that both the uniformity and the mobility are compensated, and there is no need to additionally test whether the compensated mobility meets the requirements.

[0061] Alternatively, the target setting can also be done in other ways. For example, comparing the compensation value with the offset of the threshold voltage, or directly observing whether the display screen of the organic light-emitting display is uniform everywhere. Of course, other detection methods can also be used according to needs, which are not limited here.

[0062] When it is detected that the uniformity and mobility of the driving switch return to normal after compensation, and it is determined that the uniformity compensation value and the mobility compensation value are correct, the uniformity compensation value and the mobility compensation value can be stored in the memory, and the driving data of the driving switch and the pixel can be directly compensated by using the uniformity compensation value and the mobility compensation value during the subsequent display process.

[0063] In addition, in the embodiment of the present application, before step S1, it is necessary to first enter the compensation state to complete the sensing of the threshold voltage and the compensation calculation of the uniformity and mobility. This part is performed in the non-display state, which can be after the display is turned on, or before it is turned off, or during the vertical blanking period.

[0064] As an implementation method in the embodiment of the present application, the organic light-emitting display has two working modes, one is the display mode, and the other is the compensation mode. Before step S1, the working mode of the organic light-emitting display will be first adjusted to the compensation mode; after it is detected that the uniformity of the driving switch is compensated to the set target and the uniformity compensation value and the mobility compensation value are stored in the memory of the organic light-emitting display, the working mode of the organic light-emitting display is automatically adjusted to the display mode, and the driving switch is compensated by using the uniformity compensation value and / or the mobility compensation value stored in the memory.

[0065] In this embodiment, the compensation mode can be performed at any time during the display process. This process can be manually selected by the user. After the organic light-emitting display has been used for a period of time, the user can send a compensation instruction to the organic light-emitting display. At this time, the organic light-emitting display enters the compensation mode and executes the above compensation method to compensate the driving data of the driving switch and the pixel. This process is completely selected by the user, and the execution cycle is also selected by the user to avoid affecting the display process of the organic light-emitting display.

[0066] Alternatively, in the automatic mode, before the working mode of the organic light-emitting display is adjusted to the compensation mode, the internal detection structure of the organic light-emitting display will first detect whether the uniformity and mobility in the driving switch are abnormal. If abnormal, the organic light-emitting display will display a suggestion to enter the compensation mode to remind the user that compensation is needed, or directly perform compensation; if normal, the organic light-emitting display will work normally. This method does not require the user to frequently adjust the working mode of the organic light-emitting display. The organic light-emitting display can automatically identify and compensate to ensure that the display screen does not have the problem of uneven display.

[0067] It should be noted that the limitations of each step involved in this solution do not, on the premise of not affecting the implementation of the specific solution, be regarded as limiting the order of steps. The steps written in the front can be executed first, or can be executed later, or even can be executed simultaneously. The solutions of different embodiments can be combined and applied without conflict. As long as this solution can be implemented, it should be regarded as falling within the protection scope of this application.

[0068] The above content is a further detailed description of this application in combination with specific optional implementation manners, and it cannot be determined that the specific implementation of this application is only limited to these descriptions. For those of ordinary skill in the technical field to which this application pertains, without departing from the concept of this application, several simple deductions or substitutions can still be made, and all should be regarded as falling within the protection scope of this application.

Claims

1. A compensation method for an organic light emitting display, characterized in that, Including the steps of: Obtaining a first threshold voltage and a second threshold voltage of a driving switch; Calculating an average value of all the first threshold voltages to obtain a first average value, and calculating an average value of all the second threshold voltages to obtain a second average value; Calculating a compensation value by using the first threshold voltage, the second threshold voltage, the first average value, and the second average value through a compensation formula; And Combining the compensation value into a data driving voltage to drive the corresponding driving switch, and compensating the uniformity and mobility of the driving switch; Wherein, in the step of calculating the compensation value by using the first threshold voltage, the second threshold voltage, the first average value, and the second average value through the compensation formula, substituting the first threshold voltage and the first average value into a uniformity compensation formula to calculate a uniformity compensation value, and substituting the second threshold voltage and the second average value into a mobility compensation formula to calculate a mobility compensation value; subsequently, combining the uniformity compensation value and the mobility compensation value into the data driving voltage to drive the corresponding driving switch respectively, and compensating the uniformity and mobility of the driving switch respectively; The uniformity compensation formula is: data_Vth = F(s1_data - s1_data_aver), wherein data_Vth is the uniformity compensation value, s1_data is the first threshold voltage, s1_data_aver is the first average value, and F is a compensation coefficient; The mobility compensation formula is: Data_cu = (1 - s2_data / s2_data_aver) * d_data, wherein Data_cu is the mobility compensation value, s2_data is the second threshold voltage, s2_data_aver is the second average value, and d_data is the data driving voltage; In the step of obtaining the first threshold voltage and the second threshold voltage of the driving switch, obtaining the voltage output by the driving switch in a first time period as the first threshold voltage, and obtaining the voltage output by the driving switch in a second time period as the second threshold voltage, and the time of the first time period is greater than the time of the second time period.

2. The compensation method for an organic light emitting display according to claim 1, characterized in that, F is equal to the ratio of the precision of d_data to the precision of s1_data.

3. The compensation method for an organic light emitting display according to claim 1, characterized in that, In the step of combining the compensation value into the data driving voltage to drive the corresponding driving switch and compensating the uniformity and mobility of the driving switch, only compensating the uniformity of the driving switch; or only compensating the mobility of the driving switch; Or compensating the uniformity and mobility of the driving switch simultaneously.

4. The compensation method for an organic light-emitting display according to claim 1, wherein, The uniformity compensation time of the driving switch is greater than the mobility compensation time.

5. The compensation method for an organic light emitting display according to claim 1, characterized in that, In the step of calculating the average value of all the first threshold voltages to obtain a first average value and calculating the average value of all the second threshold voltages to obtain a second average value, calculating the average value of the first threshold voltages of all the driving switches in the organic light-emitting display to obtain a first average value simultaneously, and calculating the average value of the second threshold voltages of all the driving switches in the organic light-emitting display to obtain a second average value simultaneously.

6. The compensation method for an organic light-emitting display according to claim 1, wherein, After the step of driving the corresponding driving switch by combining the compensation value into the data driving voltage to compensate for the uniformity and mobility of the driving switch, the method further includes: Detecting whether the uniformity of the driving switch is compensated to a set target; If so, storing the uniformity compensation value and the mobility compensation value in the same memory of the organic light emitting display; if not, recalculating the uniformity compensation value and the mobility compensation value.

7. The compensation method for an organic light-emitting display according to claim 6, characterized in that, Before the step of obtaining the first threshold voltage and the second threshold voltage of the driving switch, adjusting the working mode of the organic light emitting display to a compensation mode; After detecting that the uniformity of the driving switch is compensated to the set target and storing the uniformity compensation value and the mobility compensation value in the memory of the organic light emitting display, the working mode of the organic light emitting display is automatically adjusted to a display mode, and the driving switch is compensated by the uniformity compensation value and / or the mobility compensation value stored in the memory.

8. The compensation method for an organic light-emitting display according to claim 7, wherein, Before adjusting the working mode of the organic light emitting display to the compensation mode, first detecting whether the uniformity and mobility in the driving switch are abnormal. If abnormal, the organic light emitting display displays a suggestion to enter the compensation mode; if normal, the organic light emitting display works normally.

9. An organic light emitting display, characterized in that, Adopting the compensation method of the organic light emitting display according to any one of claims 1-8.

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