Display device

Abstract

The application provides a display device, comprising a display panel, a connection circuit and a display driving integrated circuit. The display panel comprises a first wire arranged at the periphery of a display area. The connection circuit comprises a second wire arranged in the connection circuit board. The display driving integrated circuit comprises an impedance detection sub-circuit and a detection circuit. The detection circuit comprises at least one matching resistor. The matching resistor forms a series loop with the first wire, the second wire and the impedance detection sub-circuit. The detection circuit is configured to control the difference between the impedance of the series loop and the first test impedance to be less than a first threshold. The application sets the detection circuit to make the impedance of the series loop equal to or close to the first test impedance of the display driving integrated circuit, thereby avoiding the problem of inaccurate detection results of the display driving integrated circuit.

Description

Technical Field

[0001] This application relates to the field of display technology, and more particularly to a display device. Background Technology

[0002] Organic Light Emitting Diode (OLED) displays are susceptible to damage from water and oxygen, which can lead to black spot issues. Therefore, during production, multiple Panel Crack Defect (PCD) tests are performed to check for cracks in the peripheral traces around the panel edges. Early screening for trace cracks can reduce the quality risks and material waste associated with EL package failures. OLED PCD testing often employs impedance detection, which involves placing a winding around the AA area of ​​the panel and using the impedance detection function integrated in the Display Driver IC (DDIC) to determine if there are any open-circuit faults caused by trace cracks.

[0003] In related technologies, display driver integrated circuits are designed with a large impedance detection range to meet different panel testing requirements. However, the test error is large under small winding impedance, which can easily cause register reading errors and misjudgments. Summary of the Invention

[0004] Embodiments of this application provide a display device to solve the problem in the related art where the impedance detection error of the display driver integrated circuit is large due to the low winding impedance of the display panel.

[0005] To solve the above problems, the technical solution provided in this application is as follows: This application provides a display device, including: The display panel includes a first trace located around the perimeter of the display area; The connection circuit includes a second trace disposed within the connection circuit board; and Display driver integrated circuit, including impedance detection sub-circuit; The detection circuit includes at least one matching resistor, which forms a series loop with the first trace, the second trace, and the impedance detection sub-circuit. The detection circuit is configured to control the difference between the impedance of the series circuit and the first test impedance to be less than a first threshold.

[0006] In one embodiment, the matching resistor is a fixed resistor or a variable resistor.

[0007] In one embodiment, the detection circuit further includes: The third trace is located outside the display area of ​​the display panel and connected in series in the series circuit.

[0008] In one embodiment, the detection circuit further includes: A first transistor, the first terminal of the first transistor is connected to the impedance detection sub-circuit, the second terminal of the first transistor is connected to one end of the matching resistor, and the control terminal of the first transistor is connected to the first output terminal of the display driver integrated circuit. The second transistor has its first terminal connected to the other end of the matching resistor, its second terminal connected to one end of the first trace, and its control terminal connected to the second output terminal of the display driver integrated circuit. The third transistor has its first terminal connected to the other end of the first trace, its second terminal connected to the impedance detection sub-circuit and connected to a reference voltage, and its control terminal connected to the third output terminal of the display driver integrated circuit.

[0009] In one embodiment, the matching resistor is a thermistor, and the display driver integrated circuit is further configured to identify the temperature of the display device based on the resistance value of the matching resistor.

[0010] In one embodiment, the detection circuit further includes: The fourth transistor has its first terminal connected to the first terminal of the second transistor, its second terminal connected to the second terminal of the third transistor, and its control terminal connected to the fourth output terminal of the display driver integrated circuit.

[0011] In one embodiment, the second transistor and the third transistor are in the same on state, and the fourth transistor is in a different on state than the second transistor.

[0012] In one embodiment, the impedance detection sub-circuit includes: A comparator, wherein the first input terminal of the comparator is connected to the first terminal of the first transistor, and the second input terminal of the comparator is connected to a preset test voltage; A detection transistor, the first terminal of which is connected to a constant current source, and the second terminal of which is connected to the first input terminal of the comparator.

[0013] In one embodiment, the comparator is configured to output a digital code corresponding to the voltage change between the first input terminal and the second input terminal.

[0014] In one embodiment, the display integrated circuit further includes: The register is configured to store the digital code and map it to the impedance range of the series circuit via a pre-stored lookup table.

[0015] This application provides a display device, including a display panel with a first trace disposed around the periphery of the display area; a connection circuit with a second trace disposed within the connection circuit board; and a display driver integrated circuit with an impedance detection sub-circuit; a detection circuit, the detection circuit including at least a matching resistor, the matching resistor forming a series loop with at least the first trace, the second trace, and the impedance detection sub-circuit; wherein the detection circuit is configured to control the difference between the impedance of the series loop and the first test impedance to be less than a first threshold. This application avoids the problem of inaccurate detection results from the display driver integrated circuit by setting the detection circuit so that the impedance of the series loop is equal to or close to the first test impedance of the display driver integrated circuit. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Appendix Figure 1 This is a schematic diagram of the PCD impedance connection relationship of the display panel in the embodiments of this application; Appendix Figure 2 This is a schematic diagram of the DIC impedance detection principle in the embodiments of this application; Appendix Figure 3 This is a schematic diagram illustrating the principle of DIC impedance detection error in the embodiments of this application; Appendix Figure 4 This is a schematic diagram of the structure of an optional display device in an embodiment of this application; Appendix Figure 5 This is a schematic diagram of another optional display device in the embodiments of this application; Appendix Figure 6 This is a schematic diagram of the display device testing method in the embodiments of this application.

[0018] Explanation of the reference numerals in the figure: 1. Display device; 100. Display panel; 110. First trace; 200. Connection circuit; 210. Second routing line; 300. Display driver integrated circuit; 310. Impedance detection sub-circuit; 311. Comparator; 312. Detection transistor; 400, Detection circuit; 410, Matching resistor; 420, Third trace. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] It will be understood that although the terms “first,” “second,” etc., may be used in this document to describe various components, these components should not be limited by these terms. These terms are used only to distinguish one component from another.

[0021] As used in this article, the singular forms “a,” “one,” and “the” are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0022] It will also be understood that the terms “comprising” and / or “including” as used herein specify the presence of a feature or component, but do not exclude the presence or addition of one or more other features or components.

[0023] Organic light-emitting diode (OLED) display devices possess numerous advantages, including self-illumination, high luminous efficiency, fast response time, high contrast, and the ability to achieve flexible displays, making them widely recognized in the industry as the display devices with the greatest development potential. Currently, in the mobile consumer electronics field, an increasing number of terminal manufacturers are choosing OLED screens as their flagship products. This is especially true in the mobile phone market, where OLED screen phones are experiencing explosive growth. During the production process at module and assembly plants, OLED mobile phone screens undergo multiple panel crack inspections to confirm whether there are cracks in the peripheral wiring at the panel edges. It is well known that the OLED light-emitting unit encapsulation is susceptible to failure due to water and oxygen, resulting in black spot problems. By screening the panel for circuit cracks in advance, the quality risks and waste of module materials caused by light-emitting unit encapsulation failure can be reduced to a certain extent.

[0024] Reference Figure 1 As shown, panel crack detection often adopts an impedance detection scheme, that is, a first trace 110 is set around the perimeter of the panel display area, and the impedance detection function integrated by the display driver IC (DDIC) 300 is used to perform impedance detection, and the circuit open circuit caused by the crack is determined according to the impedance magnitude.

[0025] Reference Figure 2The diagram shows the equivalent circuit diagram of the DDIC impedance detection principle. A constant current source outputs a fixed current, which generates a voltage drop after passing through the first trace 110. The DDIC detects the Vdut voltage and compares it with the Vref voltage. Referring to Table 1, which shows the correspondence between register values ​​and impedance, the impedance range of the line can be obtained by reading back the register and comparing it with the theoretically preset impedance and register relationship.

[0026] Table 1. Correspondence between Register Values ​​and Impedance

[0027] However, to meet the panel testing needs of different users, DDIC has a relatively large impedance detection range, referencing... Figure 3 As shown, the detection range is 0~768KΩ, and the accuracy is 6KΩ. Before the DDIC leaves the factory, it undergoes factory calibration testing based on the intermediate value of 392KΩ. If the constant current source output current is controlled by a register to be 5 microamps, Rpcd1=392KΩ, Vref1=0.53V, and according to Ohm's law, the theoretical Vdut=0.53V+5UA is calculated. 392KΩ = 2.49V. Currently, the impedance Rpcd1 of the first trace is relatively small. In actual applications, when Rpcd1 = 3KΩ, Vdut = 0.546V < the theoretical value of 2.49V. Increasing Vds will lead to a larger output current from the constant current source, resulting in significant testing errors under a smaller Rpcd1 impedance. This can easily cause register reading errors, leading to misjudgments and intercepting normal chips as abnormal ones. If the threshold for controlling the circuit is amplified, the judgment threshold may be too high, failing to intercept slightly open-circuit abnormal chips.

[0028] Reference Figure 4 As shown, this application provides a display device 1, including a display panel 100, a connection circuit, a display driver integrated circuit, and a detection circuit 400. The display panel 100 includes a first trace 110 disposed on the periphery of the display area, the connection circuit includes a second trace 210 disposed within a connection circuit board, the display driver integrated circuit includes an impedance detection sub-circuit 310, which can be used to detect the total impedance of the traces within the display device, and the detection circuit 400 includes at least a matching resistor 410, which forms a series circuit with the first trace 110, the second trace 210, and the impedance detection sub-circuit 310.

[0029] Specifically, the display driver integrated circuit is configured to determine whether the display panel 100 is qualified based on the impedance of the series circuit and the first test impedance, and the detection circuit 400 is configured to control the difference between the impedance of the series circuit and the first test impedance to be less than a first threshold.

[0030] It should be noted that the first test impedance is the impedance of the entire circuit tested by the display driver integrated circuit 300. That is, using the first test impedance as a reference value, in actual production design, the display panel 100 is considered to be designed as expected only when the difference between the design impedance of the entire circuit of the display device and the first test impedance is less than or equal to 0Ω. Therefore, theoretically, the first threshold is required to be equal to 0. The test impedance accuracy of the display driver integrated circuit 300 is determined based on its circuit design and factory testing. Therefore, in some embodiments, referring to Table 1, when the first threshold is set according to the test impedance accuracy of the display driver integrated circuit, the first threshold can be 6kΩ or 8kΩ, etc. The register value corresponding to the first threshold can also be set as shown in Table 1. It should be noted that as the test impedance accuracy of the display driver circuit improves with technological advancements, the first threshold can also be set to a smaller value.

[0031] Specifically, in some embodiments of this application, the matching resistor 410 is a fixed resistor or a variable resistor. (See also...) Figure 4 As shown, in some embodiments of this application, the connection circuit can be a flexible printed circuit board (FPC). The first trace 110 has two connection terminals, both of which are connected to the second trace 210 and then to the DDIC. In these two connection lines, the matching resistor 410 can be set on either connection line.

[0032] This scheme increases the overall impedance of the series circuit detected by the impedance detection sub-circuit 310, making the overall impedance equal to or close to the first test impedance obtained by the DDIC factory trim test, thus preventing misjudgments of the yield of the display panel 100 on the production line. It should be noted that the matching resistor 410 can be set on any one of the connection lines in this embodiment, or it can be set on both lines. Furthermore, different specifications and quantities of matching resistors 410 can be used according to different application requirements; this application does not impose any limitations on this.

[0033] In some embodiments of this application, the detection circuit 400 further includes a third trace 420, which is disposed around the display area of ​​the display panel 100 and connected in series in a series circuit. In this embodiment, while setting a matching impedance on the second trace 210, the number of turns of the first trace 110 in the display panel 100 can also be increased by setting the third trace 420, so that the total impedance in the series circuit is equal to or close to the first test resistance value. This setting helps to reduce the size of the matching resistor 410 and avoid it occupying a large space in the display device. It should be noted that since the impedance of the winding can be affected not only by the number of turns but also by the type of winding metal material, line width, and film thickness, the impedance of the winding varies greatly in different circuit designs and can be set according to specific needs. This application does not limit this setting.

[0034] In the foregoing embodiments, refer to Figure 4 As shown, the connection line between the first trace 110 and the connection circuit includes at least two bonding points, and the connection line between the connection circuit and the display driver integrated circuit includes at least four bonding points. The total impedance of the series circuit is the sum of the impedance of the first trace 110, the impedance of the matching resistor 410, and the impedances of the six bonding points. The impedance of the six bonding points is affected by the size of the bonding points themselves and the materials constituting the bonding points. In some embodiments of this application, these six bonding points all comprise anisotropic conductive film (ACF) material and are of similar size, thereby controlling the impedance of these six bonding points to be equal and negligible.

[0035] Accordingly, referring to Table 2, there is a schematic table of the impedance configuration of the series circuit in the embodiments of this application.

[0036] Table 2 Impedance Composition of Series Circuits

[0037] In some more specific embodiments of this application, the impedance of the second trace 210 is typically no more than 1Ω, and the impedance of each of the six bonding points is no more than 10Ω. With the winding impedance of the display panel 100 greater than 2kΩ and the first test impedance of the display driver integrated circuit 300 being 392kΩ, the impedance of the other parts, except for the matching resistor 410, has a negligible impact on the circuit. Therefore, in some embodiments of this application, when the matching resistor 410 is a fixed resistor or has an adjustable resistance, if the first test impedance of the display driver integrated circuit 300 is set to 392kΩ, when the winding impedance of the display panel 100 is 2kΩ, the resistance of the matching resistor 410 can be set to 390kΩ; when the winding impedance of the display panel 100 is 122kΩ, the resistance of the matching resistor 410 can be set to 270kΩ; when the winding impedance of the display panel 100 is 192kΩ, the resistance of the matching resistor 410 can be set to 200kΩ; when the winding impedance of the display panel 100 is 232kΩ, the resistance of the matching resistor 410 can be set to 160kΩ; that is, the sum of the resistance of the matching resistor 410 and the winding impedance of the display panel 100 can be approximately considered to be equal to the resistance of the first test impedance of the display driver integrated circuit.

[0038] Reference Figure 5 As shown, in some embodiments of this application, the detection circuit 400 further includes a first transistor T1, a second transistor T2, and a third transistor T3. These three transistors can control whether the matching resistor 410 is connected to the detection loop of the DDIC. Specifically, the first terminal of the first transistor T1 is connected to the impedance detection sub-circuit 310, the second terminal of the first transistor T1 is connected to one end of the matching resistor 410, and the control terminal of the first transistor T1 is connected to the first output terminal (Gout1) of the display driver integrated circuit. The first terminal of the second transistor T2 is connected to the other end of the matching resistor 410, the second terminal of the second transistor T2 is connected to one end of the first trace 110, and the control terminal of the second transistor T2 is connected to the second output terminal (Gout2) of the display driver integrated circuit. The third transistor T3 has its first terminal connected to the other end of the first trace 110, its second terminal connected to the impedance detection sub-circuit 310 and connected to a reference voltage (Vref1), and its control terminal connected to the third output terminal (Gout1) of the display driver integrated circuit. In the embodiments, the first output terminal, the second output terminal, and the third output terminal may be the Gout pin of the gate drive timing output module in the display driver integrated circuit. Although in these embodiments the matching resistor 410 is set on the connection line between the first transistor T1 and the second transistor T2, in fact, depending on different requirements, the matching resistor 410 may also be set on the connection line at other locations, and may also be controlled by more transistors. This application does not impose any limitations here.

[0039] It should be noted that the transistors used in the embodiments of this application can be thin-film transistors, field-effect transistors, or other devices with the same characteristics. Since the source and drain of the transistors are symmetrical, there is no distinction between them. In the embodiments of this application, to distinguish the source and drain of the transistor, one is called the first terminal and the other is called the second terminal. In addition, the gate of the transistor is called the control terminal. Furthermore, transistors can be classified into N-type and P-type according to their characteristics. The embodiments of this application use P-type transistors for explanation. When using a P-type transistor, the first terminal is the source of the P-type transistor, and the second terminal is the drain of the P-type transistor. When the gate input is low, the source and drain are conducting. The opposite is true for N-type transistors. It is conceivable that using an N-type transistor is something that those skilled in the art can easily conceive of without creative effort, and therefore it is also within the protection scope of the embodiments of this application.

[0040] Since the transistors used in this embodiment are all P-type transistors, the working level signal in this embodiment is a low-level signal, and the non-working level signal is a high-level signal. Therefore, when it is necessary to connect the matching resistor 410 for impedance detection of the series circuit, the first output terminal, the second output terminal, and the third output terminal can all output low-level signals, so that the first transistor T1, the second transistor T2, and the third transistor T3 are all turned on. This allows the matching resistor 410 and the first trace 110, the second trace, and other windings to be normally connected to the impedance detection sub-circuit 310, and finally, the display panel 100 is determined to have cracks by reading back the register value of DDIC.

[0041] In some embodiments of this application, the matching resistor 410 can also be a thermistor. The display driving device can be configured to identify the temperature of the display device based on the resistance value of the thermistor, and control the temperature of the display device within the normal range by adjusting the brightness, etc. The specific temperature control method is easy to implement by those skilled in the art, and will not be described in detail here.

[0042] Based on this, the detection circuit 400 may further include a fourth transistor T4. The combination of the fourth transistor T4 with the first transistor T1, the second transistor T2, and the third transistor T3 can control the matching resistor 410 for crack detection or temperature detection in the display device. Specifically, the first terminal of the fourth transistor T4 is connected to the first terminal of the second transistor T2, the second terminal of the fourth transistor T4 is connected to the second terminal of the third transistor T3, and the control terminal of the fourth transistor T4 is connected to the fourth output terminal (Gout4) of the display driver integrated circuit. Similarly, the fourth output terminal can also be the Gout pin of the gate drive timing output module in the display driver integrated circuit.

[0043] It should be noted that crack detection typically occurs during the manufacturing process of the display device, while users do not typically use the matching resistor 410 when using the device. To fully utilize the matching resistor 410, it is sometimes configured as a thermistor in certain embodiments. Although the structure of the matching resistor 410 may change with temperature, the heat generated during crack detection is relatively small, and therefore its impact on the accuracy of the crack detection structure is negligible.

[0044] In this embodiment, when the module factory or the complete machine factory performs crack detection on the display panel 100, the first output terminal, the second output terminal, and the third output terminal are all controlled to output low-level signals, while the fourth output terminal outputs a high-level signal, causing the first transistor T1, the second transistor T2, and the third transistor T3 to be turned on, and the fourth transistor T4 to be turned off. The matching resistor 410 and the first trace 110 are normally connected to the impedance detection sub-circuit 310 to realize crack detection. When the user is using the display device and crack detection is no longer needed, the first output terminal and the fourth output terminal are controlled to output low-level signals, and the second output terminal and the third output terminal output high-level signals, causing the first transistor T1 and the fourth transistor T4 to be turned on, and the second transistor T2 and the third transistor T3 to be turned off. At this time, only the matching resistor 410 is connected to the impedance detection circuit 400, and the DDIC can identify the temperature of the display device screen based on the calculated resistance value, call the compensation parameters at the corresponding temperature, or feed back to the relevant system of the display device to perform temperature compensation. This solution enables the reuse of the matching resistor 410, improving resource utilization and reducing the production cost of the display device.

[0045] More specifically, refer to Figure 5 As shown, the impedance detection sub-circuit 310 includes a comparator 311 and a detection transistor 312. The first input terminal of the comparator 311 is connected to the first terminal of the first transistor T1, and the second input terminal of the comparator 311 is connected to a preset test voltage (Vref), which corresponds to the voltage value of the first test impedance. The first terminal of the detection transistor 312 is connected to a constant current source, and the second terminal of the detection transistor 312 is connected to the second input terminal of the comparator 311. It should be noted that, although in this application… Figure 5 The circuit structure of the impedance detection sub-circuit 310 is given in the document, but this circuit structure is only used to illustrate the detection principle of the impedance detection sub-circuit 310. In actual implementation, the impedance detection sub-circuit 310 may have a more complex circuit structure, which is not limited here.

[0046] In this embodiment, comparator 311 is configured to output a digital code corresponding to the voltage change between the first input terminal and the second input terminal. Correspondingly, the display driver integrated circuit also includes a register, which is configured to store the digital code and map it to the impedance range of the series circuit through a pre-stored lookup table. Based on the impedance range, it can be determined whether the display panel 100 has cracks.

[0047] Based on this, in some embodiments, this application refers to the impedance detection process of the display device. Figure 6 As shown, it specifically includes: S1: The DDIC factory trim test adjusts the constant current source output to 5 microamps; S2: Module testing is performed by binding DDIC and FPC, and panel crack detection is carried out at the module testing site; S3: Enable PCD impedance detection during detection; S4: Read back the DDIC impedance detection register; S5: The program determines whether the readback register value is less than the program-set threshold. If it is less, the program passes and proceeds to the next test. If it is greater, the program determines that the test is not possible and the next test cannot be performed. S6: Test completed. Impedance NG risk products are downgraded and intercepted within the factory.

[0048] In summary, although the present application has disclosed the preferred embodiments as described above, the above preferred embodiments are not intended to limit the present application. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be determined by the scope defined in the claims.

Claims

1. A display device, characterized in that, include: The display panel includes a first trace located around the perimeter of the display area; The connection circuit includes a second trace disposed within the connection circuit board; as well as Display driver integrated circuit, including impedance detection sub-circuit; The detection circuit includes at least one matching resistor, which forms a series loop with the first trace, the second trace, and the impedance detection sub-circuit. The detection circuit also includes a first transistor, whose first terminal is connected to the impedance detection sub-circuit, whose second terminal is connected to one end of the matching resistor, and whose control terminal is connected to the first output terminal of the display driver integrated circuit. The display driver integrated circuit has a first test impedance set during factory trim testing, and the detection circuit is configured to make the difference between the impedance of the series circuit and the first test impedance less than a first threshold. The impedance detection sub-circuit includes: A comparator, wherein the first input terminal of the comparator is connected to the first terminal of the first transistor, and the second input terminal of the comparator is connected to a preset test voltage; A detection transistor, the first terminal of which is connected to a constant current source, and the second terminal of which is connected to the first input terminal of the comparator.

2. The display device according to claim 1, characterized in that, The matching resistor is a fixed resistor or a variable resistor.

3. The display device according to claim 2, characterized in that, The detection circuit further includes: The third trace is located outside the display area of ​​the display panel and connected in series in the series circuit.

4. The display device according to claim 1, characterized in that, The detection circuit further includes: The second transistor has its first terminal connected to the other end of the matching resistor, its second terminal connected to one end of the first trace, and its control terminal connected to the second output terminal of the display driver integrated circuit. The third transistor has its first terminal connected to the other end of the first trace, its second terminal connected to the impedance detection sub-circuit and connected to a reference voltage, and its control terminal connected to the third output terminal of the display driver integrated circuit.

5. The display device according to claim 4, characterized in that, The matching resistor is a thermistor, and the display driver integrated circuit is further configured to identify the temperature of the display device based on the resistance value of the matching resistor.

6. The display device according to claim 5, characterized in that, The detection circuit further includes: The fourth transistor has its first terminal connected to the first terminal of the second transistor, its second terminal connected to the second terminal of the third transistor, and its control terminal connected to the fourth output terminal of the display driver integrated circuit.

7. The display device according to claim 6, characterized in that, The second transistor has the same conduction state as the third transistor, while the fourth transistor has a different conduction state than the second transistor.

8. The display device according to claim 1, characterized in that, The comparator is configured to output a digital code corresponding to the voltage change between the first input terminal and the second input terminal.

9. The display device according to claim 8, characterized in that, The display driver integrated circuit also includes: The register is configured to store the digital code and map it to the impedance range of the series circuit via a pre-stored lookup table.

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