OLED display panel, OLED start-up voltage detection circuit and detection method thereof

Abstract

The present invention discloses an OLED display panel, an OLED turn-on voltage detection circuit, and a detection method thereof. The OLED display panel includes a plurality of pixel units arranged in a matrix, each pixel unit including an organic light-emitting diode (OLED), the cathode of which is connected to a common voltage. The turn-on voltage detection circuit includes: a plurality of second switching tubes, each with a first conduction terminal connected to the anode of a corresponding OLED; a test voltage generation module for providing a test voltage to the second conduction terminals of the plurality of second switching tubes according to a preset voltage range from low to high when the plurality of second switching tubes are turned on; an optical brightness measurement device for detecting the luminance of the OLED and comparing the luminance with a preset luminance; and a storage module for storing the turn-on voltages of the plurality of OLEDs on the display panel based on the detection results of the optical brightness measurement device. This allows detection of the OLED turn-on voltage solely for the variable of evaporation.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to an OLED display panel, an OLED start-up voltage detection circuit and a detection method thereof. Background Art

[0002] OLED (Organic Light-Emitting Diode) is an emerging flat-panel display device. Due to its advantages such as self-luminescence, high contrast, and wide color gamut, as well as simple preparation process, low cost, low power consumption, and easy realization of flexible display, it has broad application prospects.

[0003] Existing technology typically forms OLEDs through an evaporation process. However, significant variability exists within the evaporation process. For example, the high temperatures involved in the EL layer evaporation process cause the mask to thermally expand and deform, resulting in uneven EL layers across the individual OLED devices that form the pixels of the OLED display panel. This, in turn, causes differences in the turn-on voltage across these OLED devices. This variability in OLED turn-on voltage is influenced not only by evaporation but also by factors such as pixel circuit variability. There's no way to address this specific factor, so individual OLED devices must be individually adjusted during OLED display panel production to ensure optimal display quality. This cumbersome process results in lengthy production times.

[0004] To detect the OLED turn-on voltage solely due to the evaporation factor, existing technologies include methods such as detecting the OLED turn-on voltage by checking the conduction of the sub-pixel PN junction or by using independent mask production. However, the former is affected by variations in sub-pixel threshold voltage, while the latter requires integration with the pixel circuit during mass production, both of which are affected by the pixel circuit. Therefore, a new OLED turn-on voltage detection circuit is needed to address these issues. Summary of the Invention

[0005] In view of the above problems, an object of the present invention is to provide an OLED display panel, an OLED turn-on voltage detection circuit and a detection method thereof, so that the OLED turn-on voltage can be detected based on only the variable factor of evaporation.

[0006] According to one aspect of the present invention, a turn-on voltage detection circuit for an OLED display panel is provided. The OLED display panel includes a plurality of pixel units arranged in a matrix, each pixel unit including an organic light-emitting diode, wherein the cathode of the organic light-emitting diode is connected to a common voltage. The turn-on voltage detection circuit includes: a plurality of second switching tubes, wherein the first conduction end of each second switching tube is connected to the anode of the corresponding organic light-emitting diode; a test voltage generation module for providing a test voltage to the second conduction ends of the plurality of second switching tubes according to a preset voltage range from low to high when the plurality of second switching tubes are turned on; an optical brightness measurement device for detecting the luminance of the organic light-emitting diode and comparing the luminance with a preset brightness; and a storage module for storing the turn-on voltage of each of the plurality of organic light-emitting diodes on the display panel according to the detection results of the optical brightness measurement device.

[0007] Optionally, the optical brightness measurement device is used to output the serial number of the organic light emitting diode when the detected light emitting brightness of the organic light emitting diode reaches the preset brightness.

[0008] Optionally, the storage module is configured to read the test voltage output by the test voltage generating module while receiving the number of the organic light emitting diode, obtain the turn-on voltage of the organic light emitting diode based on the test voltage, and store the number of the organic light emitting diode and its corresponding turn-on voltage.

[0009] Optionally, the OLED start-up voltage detection circuit also includes multiple operational amplifiers, the positive input terminals of the multiple operational amplifiers are connected to the test voltage generation module, and the negative input terminal and output terminal of each operational amplifier are connected to the second conduction terminals of the multiple second switching tubes in the corresponding column.

[0010] Optionally, each pixel unit further includes: a pixel circuit connected to the anode of the corresponding organic light emitting diode; a first switch tube, wherein a first conduction end of the first switch tube is connected to the pixel circuit, and a second conduction end is connected to the output end of the corresponding operational amplifier.

[0011] Optionally, the first switch tube is used to be turned on during a display phase of the display panel, and the second switch tube is used to be turned on during a light-on voltage detection phase of the display panel.

[0012] Optionally, the test voltage generating module is further configured to output a corresponding display voltage to a corresponding pixel circuit according to the number and the turn-on voltage of each organic light emitting diode stored in the storage module during the display phase.

[0013] According to another aspect of the present invention, a method for detecting an OLED turn-on voltage is provided, comprising: providing a test voltage to the second conduction terminals of a plurality of second switching tubes according to a preset voltage range from low to high when the plurality of second switching tubes are turned on; detecting the luminance of the organic light-emitting diodes and comparing the luminance with a preset luminance; and storing the turn-on voltage of each of the plurality of organic light-emitting diodes based on the detection result.

[0014] Optionally, storing the respective turn-on voltages of the plurality of organic light-emitting diodes according to the detection results includes: outputting the number of the organic light-emitting diode to a storage module when the detected luminance of the organic light-emitting diode reaches the preset brightness; the storage module reading the test voltage upon receiving the number of the organic light-emitting diode, obtaining the turn-on voltage of the organic light-emitting diode according to the test voltage, and storing the number of the organic light-emitting diode and its corresponding turn-on voltage.

[0015] Optionally, obtaining the turn-on voltage of the organic light emitting diode according to the test voltage includes: reading a pre-stored common voltage value; and using the difference between the test voltage and the common voltage as the turn-on voltage of the organic light emitting diode.

[0016] According to another aspect of the present invention, an OLED display panel is provided for executing the above-mentioned OLED turn-on voltage detection method.

[0017] According to the OLED display panel, OLED turn-on voltage detection circuit, and detection method provided by embodiments of the present invention, during the OLED turn-on voltage detection phase of the OLED display panel, a test voltage generation module simultaneously outputs test voltages of equal voltage values ​​from low to high within a preset voltage range to the anode of each organic light-emitting diode. The test voltage transmission path does not need to pass through the pixel circuit, effectively detecting the turn-on voltage of each organic light-emitting diode while avoiding the influence of the pixel circuit. This effectively determines the vapor deposition differences of each organic light-emitting diode and the cause of display unevenness (mura) of the OLED display panel, thereby specifically compensating for the turn-on voltage of each organic light-emitting diode during the display phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0019] Figure 1 It shows a connection diagram of an OLED turn-on voltage detection circuit according to a first embodiment of the present invention;

[0020] Figure 2It shows a connection diagram of an OLED turn-on voltage detection circuit according to a second embodiment of the present invention;

[0021] Figure 3 A flow chart of an OLED turn-on voltage detection method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0022] Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, identical components or modules are represented by identical or similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0023] It should be understood that in the following description, a "circuit" may include a single or multiple combined hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by programmable circuits. When an element or circuit is said to be "connected to" another element or an element or circuit is said to be "connected" between two nodes, it can be directly coupled or connected to the other element or there can be intermediate elements. The connection between the elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intermediate elements between the two.

[0024] In addition, it should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0025] Before using an OLED display panel, due to the unevenness of vapor deposition, it is necessary to first detect the turn-on voltage of all organic light-emitting diodes (OLEDs) after vapor deposition to facilitate targeted improvements so that the OLED display panel can display the image uniformly during use.

[0026] Figure 1 FIG. 4 shows a connection diagram of an OLED start-up voltage detection circuit according to a first embodiment of the present invention. Figure 1The OLED display panel shown includes eight pixel units 10 arranged in two rows and four columns. Each pixel unit 10 includes a pixel circuit 20, a first switching transistor T1, a second switching transistor T2, and an organic light-emitting diode OLED. The number of pixel units 10 in the OLED display panel of this embodiment is not limited to eight and can be set according to actual needs.

[0027] The first conduction end of the first switch tube T1 is connected to the pixel circuit 20, the anode of the organic light emitting diode OLED is connected to the pixel circuit 20, and the cathode is connected to the common voltage VCOM (not shown in the figure). The first conduction end of the second switch tube T2 is connected to the intermediate node A between the pixel circuit 20 and the organic light emitting diode OLED.

[0028] To facilitate calculation of the turn-on voltage, the OLED turn-on voltage detection circuit provided in the embodiments of the present invention maintains a constant common voltage VCOM applied to all organic light-emitting diodes (OLEDs) during the OLED turn-on voltage detection phase of the OLED display panel. However, in practice, the turn-on voltage applied to each organic light-emitting diode (OLED) may be adjusted based on actual circumstances, and the present invention does not impose any specific limitations thereon.

[0029] The OLED turn-on voltage detection circuit also includes a test voltage generation module 40 and a storage module 50 connected to the test voltage generation module 40. The test voltage generation module 40 is used to simultaneously output test voltages VDATA with equal voltage values ​​from low to high according to a preset voltage range to the second conduction end of the corresponding second switch tube T2 during the OLED turn-on voltage detection phase of the OLED display panel, thereby applying the test voltage VDATA to the anode of each organic light-emitting diode OLED to make the voltage across each organic light-emitting diode OLED equal, that is, the difference between the test voltage VDATA and the common voltage VCOM, thereby facilitating the calculation of the turn-on voltage of each organic light-emitting diode OLED.

[0030] Furthermore, the preset voltage range may be set according to the range of a turn-on voltage of a general organic light emitting diode (OLED), and is not specifically limited in the embodiment of the present invention.

[0031] The OLED turn-on voltage detection circuit also includes an optical measurement device 60, which is connected to the storage module 50 and is used to detect the luminance of each organic light-emitting diode (OLED) during the OLED turn-on voltage detection phase. When the luminance of any organic light-emitting diode (OLED) reaches a preset brightness, such as 1 nit, the number of that organic light-emitting diode (OLED) is input into the storage module 50. Each organic light-emitting diode (OLED) has a corresponding number, and the specific numbering method can be selected based on actual conditions. The present invention is not limited to this numbering method for the organic light-emitting diodes (OLED).

[0032] When receiving the number of any organic light emitting diode OLED, the storage module 50 reads the test voltage VDATA currently output by the test voltage generating module 40 to calculate the turn-on voltage of the organic light emitting diode OLED, and stores the number of the organic light emitting diode OLED and its corresponding turn-on voltage until the numbers of all organic light emitting diodes OLED and their corresponding turn-on voltages are obtained.

[0033] Furthermore, the test voltage generating module 40 and the storage module 50 may be integrated into a SOP (System On Panel).

[0034] Furthermore, in the embodiment of the present invention, the turn-on voltage of the organic light emitting diode OLED is equal to the difference between the test voltage VDATA and the common voltage VCOM when the luminance of the organic light emitting diode OLED reaches a preset luminance.

[0035] Furthermore, the storage module 50 also stores the voltage value of the common voltage VCOM.

[0036] The OLED light-on voltage detection circuit provided by the embodiment of the present invention is described in detail below through the OLED light-on voltage detection stage and the display stage of the OLED display panel.

[0037] During the OLED turn-on voltage detection phase, the first switch T1 of each pixel unit 10 is turned off and the second switch T2 is turned on. The test voltage generation module 40 simultaneously outputs test voltages VDATA of equal value to the second conduction terminal of the corresponding second switch T2 within a preset voltage range, from low to high. This applies the test voltage VDATA to the anode of each organic light-emitting diode OLED. The optical measurement device 60 detects the luminance of each organic light-emitting diode OLED while the test voltage generation module 40 outputs the test voltage VDATA. When the luminance of any organic light-emitting diode OLED reaches a preset brightness, the number of the organic light-emitting diode OLED is input into the storage module 50. Upon receiving the number of any organic light-emitting diode OLED, the storage module 50 reads the test voltage VDATA currently output by the test voltage generation module 40, calculates the turn-on voltage of the organic light-emitting diode OLED based on the currently output test voltage VDATA, and stores the number of the organic light-emitting diode OLED and its corresponding turn-on voltage until the numbers and corresponding turn-on voltages of all organic light-emitting diodes OLED are obtained.

[0038] The specific calculation method for calculating the turn-on voltage of the organic light emitting diode OLED based on the currently output test voltage VDATA is to read the voltage value of the common voltage VCOM pre-stored in the storage module 50, and calculate the difference between the voltage values ​​of the current test voltage VDATA and the common voltage VCOM, and use it as the turn-on voltage of the organic light emitting diode OLED.

[0039] During the display phase, the OLED turn-on voltage detection circuit can compensate the turn-on voltage of the organic light-emitting diodes (OLEDs) using the display voltages VA / VB / VC / VD and / or the common voltage VCOM, ensuring that the turn-on brightness of all OLEDs (OLEDs) is consistent, resulting in a uniform display. When compensating the turn-on voltage of the OLEDs, it is sufficient to ensure that the display voltage VA / VB / VC / VD applied to the anode of any OLED (OLED) is equal to the sum of the common voltage VCOM and the turn-on voltage of that OLED (OLED).

[0040] The OLED turn-on voltage detection circuit provided by the embodiment of the present invention is described below by taking the display voltage VA / VB / VC / VD to compensate for the turn-on voltage of the organic light emitting diode OLED as an example.

[0041] During the display phase, the first switch tube T1 of each pixel unit 10 is turned on and the second switch tube T2 is turned off. The voltage value of the common voltage VCOM applied to the cathode of each organic light-emitting diode OLED is equal. The test voltage generation module 40 reads the number of each organic light-emitting diode OLED and its turn-on voltage in the storage module 50, and outputs the corresponding display voltage VA / VB / VC / VD to the anode of the corresponding organic light-emitting diode OLED according to the turn-on voltage of each organic light-emitting diode OLED. The pixel circuit 20 applies the display voltage VA / VB / VC / VD to the anode of the organic light-emitting diode OLED as needed to achieve uniform display of the display panel.

[0042] According to the OLED turn-on voltage detection circuit provided in the first embodiment of the present invention, during the OLED turn-on voltage detection phase, the test voltage generation module 40 simultaneously outputs the test voltage VDATA of equal voltage values ​​from low to high within a preset voltage range to the anode of each organic light-emitting diode OLED, without passing through the pixel circuit 20. This effectively detects the turn-on voltage of each organic light-emitting diode OLED while avoiding the influence of the pixel circuit 20, thereby effectively determining the vapor deposition differences of each organic light-emitting diode OLED and the cause of the uneven display of the OLED display panel, thereby specifically compensating the turn-on voltage of each organic light-emitting diode OLED during the display phase.

[0043] Figure 2 FIG. 1 is a connection diagram of an OLED turn-on voltage detection circuit according to a second embodiment of the present invention.

[0044] The structure of the OLED turn-on voltage detection circuit according to the second embodiment of the present invention is substantially the same as that of the OLED turn-on voltage detection circuit according to the first embodiment of the present invention. Only the differences between the two are described below.

[0045] like Figure 2 As shown, the OLED turn-on voltage detection circuit also includes an operational amplifier 30. In this embodiment, the operational amplifier 30 functions as a voltage follower to ensure the complete transmission of the voltage signal. Its negative input and output are connected and are used to output the voltage signal. Each column of pixel units 10 corresponds to an operational amplifier 30. The second conductive ends of the first switch transistor T1 and the second switch transistor T2 of each column of pixel units 10 are connected in series with the negative input and output ends of the corresponding operational amplifier 30. The operational amplifier 30 is used to input the test voltage VDATA output by the test voltage generation module 40 to the corresponding second switch transistor T2 during the OLED turn-on voltage detection phase of the OLED display panel, and to input the display voltage VA / VB / VC / VD generated by the test voltage VDATA generation module 40 to the corresponding first switch transistor T1 during the display phase of the OLED display panel.

[0046] The OLED turn-on voltage detection circuit provided according to the second embodiment of the present invention transmits the voltage signal through the operational amplifier, thereby ensuring the complete transmission of the voltage signal.

[0047] The embodiment of the present invention further provides an OLED light-on voltage detection method for detecting the OLED light-on voltage of an OLED display panel. Figure 3 The flowchart of the OLED turn-on voltage detection method according to an embodiment of the present invention is shown, which specifically includes the following steps:

[0048] S1: When the plurality of second switch tubes T2 are turned on, providing a test voltage VDATA to the second conduction terminals of the plurality of second switch tubes T2 according to a preset voltage range from low to high;

[0049] In step S1, the first switch tube T1 is turned off and the second switch tube T2 is turned on. The test voltage generating module 40 directly outputs a test voltage VDATA with an equal voltage value to the second conduction end of each second switch tube T2 in accordance with a preset voltage range and from low to high without passing through the pixel circuit 20, thereby applying the test voltage VDATA to the anode of each organic light emitting diode OLED.

[0050] S2: Detecting the luminance of each organic light emitting diode (OLED) and comparing the luminance with a preset brightness;

[0051] In step S2 , while the test voltage generating module 40 outputs the test voltage VDATA, the optical measuring device 60 detects the light emitting brightness of each organic light emitting diode OLED and compares the light emitting brightness with a preset brightness.

[0052] S3: storing respective turn-on voltages of the plurality of organic light emitting diodes OLED according to the detection result.

[0053] In step S3, when the optical measuring device 60 detects that the luminance of any organic light-emitting diode OLED is at a preset brightness, the serial number of the organic light-emitting diode OLED is input into the storage module 50. Upon receiving the serial number of any organic light-emitting diode OLED, the storage module 50 reads the test voltage VDATA currently output by the test voltage generating module 40 and calculates the turn-on voltage of the organic light-emitting diode OLED. The specific calculation method is to read the voltage value of the common voltage VCOM pre-stored in the storage module 50, calculate the difference between the current test voltage VDATA and the common voltage VCOM, and use the difference as the turn-on voltage of the organic light-emitting diode OLED. The storage module 50 stores the calculated turn-on voltages of the organic light-emitting diodes OLED and their serial numbers until the turn-on voltages of all organic light-emitting diodes OLED are obtained.

[0054] The present invention further provides an OLED display panel for executing the above-mentioned OLED turn-on voltage detection method.

[0055] The embodiments of the present invention are as described above, but these embodiments do not describe all the details in detail, nor do they limit the invention to specific embodiments. Obviously, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and modify and use it based on the present invention. The scope of protection of the present invention shall be based on the scope defined by the claims of the present invention and their equivalents.

Claims

1. A turn-on voltage detection circuit for an OLED display panel, the OLED display panel comprising a plurality of pixel units arranged in a matrix, each pixel unit comprising an organic light-emitting diode (OLED), the cathode of the OLED being connected to a common voltage, the turn-on voltage detection circuit comprising: a plurality of second switching tubes, wherein the first conduction end of each second switching tube is connected to the anode of the corresponding organic light emitting diode; a test voltage generating module, configured to provide a test voltage to the second conduction ends of the plurality of second switch tubes according to a preset voltage range from low to high when the plurality of second switch tubes are turned on; an optical brightness measuring device, configured to detect the luminance of the organic light emitting diode and compare the luminance with a preset brightness; as well as a storage module, configured to store the respective turn-on voltages of the plurality of organic light emitting diodes on the display panel according to the detection result of the optical brightness measurement device; Wherein, each of the pixel units further includes: a pixel circuit connected to the anode of the corresponding organic light emitting diode; a first switch tube, wherein a first conductive end of the first switch tube is connected to the pixel circuit, and a second conductive end of the first switch tube is connected to the second conductive end of the second switch tube; The first switch tube is used to be turned on during the display phase of the display panel, and the second switch tube is used to be turned on during the turn-on voltage detection phase of the display panel.

2. The turn-on voltage detection circuit according to claim 1, wherein: The optical brightness measuring device is used to output the serial number of the organic light emitting diode when the detected light emitting brightness of the organic light emitting diode reaches the preset brightness.

3. The turn-on voltage detection circuit according to claim 2, wherein: The storage module is configured to read the test voltage output by the test voltage generating module while receiving the number of the organic light emitting diode, obtain the turn-on voltage of the organic light emitting diode according to the test voltage, and store the number of the organic light emitting diode and its corresponding turn-on voltage.

4. The turn-on voltage detection circuit according to claim 1 , further comprising: Multiple operational amplifiers, the positive input terminals of the multiple operational amplifiers are connected to the test voltage generating module, and the negative input terminal and output terminal of each operational amplifier are connected to the second conduction terminals of the multiple second switching tubes in a corresponding column.

5. The turn-on voltage detection circuit according to claim 4, wherein: The test voltage generating module is further configured to output a corresponding display voltage to a corresponding pixel circuit according to the number and the start-up voltage of each organic light emitting diode stored in the storage module during the display phase.

6. A method for detecting an OLED display panel turn-on voltage using the OLED display panel turn-on voltage detection circuit according to any one of claims 1 to 5, comprising: When the plurality of second switching tubes are turned on, providing a test voltage to the second conducting ends of the plurality of second switching tubes according to a preset voltage range from low to high; detecting the light emitting brightness of the organic light emitting diode and comparing the light emitting brightness with a preset brightness; The turn-on voltages of the organic light emitting diodes are stored according to the detection results.

7. The OLED turn-on voltage detection method according to claim 6, wherein: Storing the respective turn-on voltages of the plurality of organic light emitting diodes according to the detection result includes: outputting the serial number of the organic light emitting diode to a storage module when the detected light emitting brightness of the organic light emitting diode reaches the preset brightness; The storage module reads the test voltage upon receiving the number of the organic light emitting diode, obtains the turn-on voltage of the organic light emitting diode according to the test voltage, and stores the number of the organic light emitting diode and its corresponding turn-on voltage.

8. The OLED turn-on voltage detection method according to claim 7, wherein: The step of obtaining a turn-on voltage of the organic light emitting diode according to the test voltage includes: Reading a pre-stored common voltage value; The difference between the test voltage and the common voltage is used as the turn-on voltage of the organic light emitting diode.

9. An OLED display panel, configured to execute the OLED turn-on voltage detection method according to any one of claims 6 to 8.

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