A method for improving low grayscale response time of organic light emitting display device

Abstract

The present invention discloses a method for improving the low grayscale response time of an organic light-emitting display device, wherein the organic light-emitting display device comprises at least one panel display driving unit, wherein the panel display driving unit comprises a first reset module and a second reset module, wherein the first reset module is used to provide a first reset voltage in the initialization phase, and the second reset module is used to provide a second reset voltage in the display data writing phase, and a peripheral driving circuit is provided, wherein the peripheral driving circuit comprises a picture detection module, a first compensation driving module, and a second compensation driving module. The present invention sets a picture detection module, and when the picture meets the limited conditions, adjusts the initial voltage value of the gate of the driving tube of the first frame, increases the voltage of the driving tube, and realizes an increase in the current of the driving tube, so as to improve the brightness of the overall display, and the frame holding curve is also flatter, and the screen shaking phenomenon is improved.

Description

Technical Field

[0001] The present invention belongs to the field of image processing technology, and in particular relates to a method for improving the low grayscale response time of an organic light emitting display device. Background Art

[0002] At present, more and more mobile devices choose Organic Light-Emitting Diode (OLED) display screens, and use pulse width modulation (PWM) dimming to adjust the backlight brightness of OLED display, that is, when the pulse signal is at a high level, the OLED pixel is controlled to be bright, and when the pulse signal is at a low level, the OLED is controlled to be off, and the pixel brightness is controlled by controlling the duty cycle of the high level of the pulse.

[0003] At present, there is a problem of uneven display brightness in the OLED display field (consumer mobile phones, wearables, and notebooks). The main reason for this problem is the difference in threshold voltage. In the prior art, in order to eliminate the difference in threshold voltage caused by process fluctuations, the array unit basically uses 7T1C or 8T1C pixel circuits as the driving circuit of OLED devices. This is because the 7T1C pixel circuit and the 8T1C pixel circuit have a threshold voltage compensation function.

[0004] Take the 7T1C pixel circuit as an example. Figure 1 As shown, at time T1, the initialization is performed and the gate of the driving tube M3 is reset. At time T2, the display data data is transmitted to the N1 node of the driving tube M3, and the threshold voltage (recorded as Vth) is compensated at the same time, and the anode of the OLED at the N4 node is reset. At time T3, light is emitted. The voltage value of Vref does not change during the entire display process.

[0005] However, the above method has the following problems: when the Always On Display (AOD) is low frequency, the low grayscale frame rate is poorly maintained, such as Figure 2 In addition, there is also a circuit in the prior art that resets the N2 node, and the frame rate retention will be significantly improved, such as Figure 2 As shown by the dotted line, however, since the M3 tubes emit light at the same time, they are subject to different bias voltages and have different threshold voltage offsets, so there will be afterimages or the brightness of the first frame will not be reached. There will also be color cast problems.

[0006] When a P-type thin film transistor (TFT) is subjected to a forward bias (PBS), the Vth will drift positively, resulting in a more serious Vth positive drift at low grayscale. In this way, when the screen is black in the previous frame and white in the next frame, the brightness of the white will not be enough, resulting in visual ghosting. Figure 3As shown, we assume that the OLED screen is divided into O screen and P screen, and the vertical axis is the screen brightness. Before the first frame, the O screen is black. In the first frame, the brightness of the O screen is only a part. In the second frame, the brightness of the O screen is normal. At the same time, before the first frame, the P screen is white. In the first frame, the P screen becomes black, and then in the second frame, the brightness of the P screen is only a part. After the second frame, the brightness of the P screen is normal, so there will be a ghosting phenomenon.

[0007] like Figure 4 As shown in the figure, the reason for the response time is that the previous frame of the picture has a different bias voltage on the TFT, which affects the display of the current frame of the picture. For example, when the standby time is displayed at 1Hz, when switching from 1:05 to 1:06 in the figure, because the brightness of the first frame during black-to-white switching does not reach the normal brightness, then in the first second, the black-to-white position corresponding to the number 6 will be obviously dark.

[0008] like Figure 5 As shown, when the screen is black, the N1 potential is higher and the Vth is more positive. When black is cut to white, the TFT (thin film transistor) characteristics cannot be quickly transformed into the white screen TFT characteristic 3. The Vth2 corresponding to the Vth compensation is more positive than the characteristic curve Vth of the normal white screen, so the display brightness will be lower. When the next frame continues to be a white screen, since the previous frame has been biased by 1 frame of white, the curve characteristic is characteristic 3, so the brightness of the second frame is relatively normal white. This phenomenon is called TFT hysteresis effect, that is, the smear phenomenon. Summary of the invention

[0009] In view of this, one of the objects of the present invention is to provide a method for improving the low grayscale response time of an organic light-emitting display device. By adding a detection module, when the picture meets the specified conditions, the initial voltage value of the gate of the driving tube of the first frame is adjusted, the voltage of the driving tube is increased, and the current of the driving tube is increased to improve the overall display brightness. The frame holding curve is also flatter and the screen jitter phenomenon is improved.

[0010] To achieve the above-mentioned object, a first aspect of the present invention provides a method for improving the low grayscale response time of an organic light-emitting display device, wherein the organic light-emitting display device comprises at least one panel display driving unit, wherein the panel display driving unit comprises a first reset module and a second reset module, wherein the first reset module is used to provide a first reset voltage in an initialization phase, and the second reset module is used to provide a second reset voltage in a display data writing phase, and wherein the method comprises the following steps:

[0011] Step S1: Determine whether the grayscale values ​​of the previous frame and the current frame meet the preset compensation conditions.

[0012] The compensation condition is specifically: the grayscale value of the previous frame is the lowest or lower than a preset low grayscale threshold, and the grayscale value of the current frame is higher than that of the previous frame;

[0013] Step S2-1: When the compensation condition is met, adjusting the first reset module to change the first reset voltage to a preset first compensation reset voltage, and adjusting the second reset module to change the second reset voltage to a preset second compensation reset voltage;

[0014] Step S2-2: When the compensation condition is not met, the first reset module maintains or resumes providing the first reset voltage, and the second reset module maintains or resumes providing the second reset voltage.

[0015] Preferably, the peripheral driving circuit includes a picture detection module, a first compensation driving module and a second compensation driving module;

[0016] The first compensation driving module and the second compensation driving module are electrically connected to the picture detection module respectively;

[0017] The first compensation driving module is electrically connected to the first reset module;

[0018] The second compensation driving module is electrically connected to the second reset module;

[0019] The picture detection module is used to execute step S1;

[0020] The first compensation driving module is used to adjust the first reset module so that the first reset voltage changes to the first compensation reset voltage, and the second compensation driving module is used to adjust the second reset module so that the second reset voltage changes to the second compensation reset voltage.

[0021] Preferably, the first compensation reset voltage is lower than the first reset voltage, and the second compensation reset voltage is higher than the second reset voltage.

[0022] Preferably, the difference between the first reset voltage and the first compensation reset voltage is less than 0.5V.

[0023] Preferably, the second compensation reset voltage is lower than the sum of the common ground voltage of the panel display driving unit and the start-up voltage of the organic light emitting display device.

[0024] Preferably, the control signal timing of the organic light-emitting display device has a display area and a non-display area. When the compensation condition is met, the picture detection module adjusts the first reset module through the first compensation driving module in the non-display area of ​​the current frame so that the first reset voltage changes to a preset first compensation reset voltage, and adjusts the second reset module through the second compensation driving module in the non-display area of ​​the current frame so that the second reset voltage changes to a preset second compensation reset voltage.

[0025] A second aspect of the present invention provides an organic light emitting display device for improving low grayscale response time, characterized in that it comprises at least one panel display driving unit, wherein the panel display driving unit comprises a peripheral driving circuit, a first reset module and a second reset module;

[0026] The peripheral driving circuit includes a picture detection module, a first compensation driving module and a second compensation driving module;

[0027] The first compensation driving module and the second compensation driving module are electrically connected to the picture detection module respectively;

[0028] The first compensation driving module is electrically connected to the first reset module;

[0029] The second compensation driving module is electrically connected to the second reset module;

[0030] The picture detection module is used to execute step S1;

[0031] The first compensation driving module is used to adjust the first reset module so that the first reset voltage changes to the first compensation reset voltage, and the second compensation driving module is used to adjust the second reset module so that the second reset voltage changes to the second compensation reset voltage.

[0032] The method disclosed in the present invention for improving the low grayscale response time of an organic light-emitting display device has the following beneficial effects:

[0033] (1) By adding a picture detection module, when the picture meets the specified conditions, the initial voltage value of the driving tube gate of the first frame is adjusted to increase the voltage of the driving tube and increase the current of the driving tube to improve the overall display brightness. The frame retention curve is also smoother and the screen jitter phenomenon is improved.

[0034] (2) By adjusting the anode voltage of the organic light emitting diode display screen and increasing the anode potential of the organic light emitting diode display screen, the capacitance of the organic light emitting diode display screen is quickly filled, thereby greatly optimizing the color cast problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 is a schematic diagram of a pixel compensation circuit in the prior art;

[0037] Figures 2 to 5Schematic diagram of the principle of the smear phenomenon;

[0038] Figure 6 A schematic diagram of a method for improving low grayscale response time of an organic light emitting display device disclosed in the present invention;

[0039] Among them: 1 panel display driving unit; 2 peripheral driving circuit; 3 first reset module; 4 second reset module; 5 first light control module; 6 second light control module; 7 picture detection module; 8 first compensation driving module; 9 second compensation driving module; 10 light emitting module. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The embodiment of the present invention discloses a method for improving the low grayscale response time of an organic light emitting display device. The organic light emitting display device includes at least one panel display driving unit 1. The panel display driving unit 1 includes a first reset module 3 and a second reset module 4. The first reset module 3 is used to provide a first reset voltage in an initialization phase. The second reset module 4 is used to provide a second reset voltage in a display data writing phase. The method is characterized in that the method comprises the following steps:

[0042] Step S1: Determine whether the grayscale values ​​of the previous frame and the current frame meet the preset compensation conditions.

[0043] The compensation conditions are as follows: the grayscale value of the previous frame is the lowest or lower than a preset low grayscale threshold, and the grayscale value of the current frame is higher than that of the previous frame;

[0044] Step S2-1: When the compensation condition is met, the first reset module 3 is adjusted to change the first reset voltage to a preset first compensation reset voltage, and the second reset module 4 is adjusted to change the second reset voltage to a preset second compensation reset voltage;

[0045] Step S2-2: When the compensation condition is not met, the first reset module 3 maintains or resumes providing the first reset voltage, and the second reset module 4 maintains or resumes providing the second reset voltage.

[0046] In actual situations, when the picture detection module 7 detects that no change from low grayscale to high grayscale occurs, or the changed picture stays for only one frame, the first reset module 3 maintains or resumes providing the first reset voltage, and the second reset module 4 maintains or resumes providing the second reset voltage, so that both the first reset voltage and the second reset voltage do not change.

[0047] When the compensation condition is met, the image detection module 7 adjusts the first reset module 3 through the first compensation driving module 8 so that the first reset voltage changes to a preset first compensation reset voltage, and adjusts the second reset module 4 through the second compensation driving module 9 so that the second reset voltage changes to a preset second compensation reset voltage;

[0048] For example, in the clock mode of the screen-off display, the picture on the organic light-emitting display device basically changes once per second, or once per minute. When the picture detection module 7 detects a transition from a low grayscale to a high grayscale, and the changed picture is maintained for at least 2 frames, the first compensation driving module 8 adjusts the first reset module 3 so that the first reset voltage changes to a preset first compensation reset voltage, and adjusts the second reset module 4 through the second compensation driving module 9 so that the second reset voltage changes to a preset second compensation reset voltage. The process occurs in the non-display area, and when the voltage is displayed, a stable output is achieved without jumps.

[0049] It should be noted that, either the first reset voltage or the second reset voltage may be selected to be changed.

[0050] Preferably, the first compensation reset voltage is lower than the first reset voltage, and the second compensation reset voltage is higher than the second reset voltage.

[0051] Preferably, in order to achieve the effect of compensating the threshold voltage, the difference between the first reset voltage and the first compensation reset voltage is recommended to be less than 0.5V.

[0052] Preferably, the second compensation reset voltage is lower than the sum of the common ground voltage of the panel display driving unit and the turn-on voltage of the organic light-emitting display device. In order to avoid pixel stealth, the second reset voltage and the second compensation reset voltage are recommended to be less than the sum of the common ground voltage and the turn-on voltage of the organic light-emitting display device. The relationship is: Vint2<Vint2p<ELVSS+Voled, wherein: ELVSS is the common ground voltage, and Voled is the turn-on voltage of the organic light-emitting display device.

[0053] Preferably, the control signal timing of the organic light-emitting display device has a display area and a non-display area. When the compensation condition is met, the picture detection module 7 adjusts the first reset module 3 through the first compensation driving module 8 in the non-display area of ​​the current frame so that the first reset voltage changes to a preset first compensation reset voltage, and adjusts the second reset module 4 through the second compensation driving module 9 in the non-display area of ​​the current frame so that the second reset voltage changes to a preset second compensation reset voltage.

[0054] To explain in detail, when the first reset voltage (recorded as Vint1) is written to the first reset module 3, the display screen of the next frame is detected in advance in the non-display area. If the screen is not updated, Vint1 will not be changed (the previous frame is recorded as Frame0, and the current frame is recorded as Frame1), that is, when Frame0=Frame1, the Vint1 voltage will not be adjusted. In the current frame Frame0 screen, the black or low grayscale position is refreshed to a brighter grayscale screen in the current frame Frame1, so Vint1 is adjusted in the non-display area of ​​the two frames, and Vint1 is adjusted to a more negative value, that is, the first compensation reset voltage (recorded as Vint1N), Vint1>Vint1N. To improve the overall brightness. If there is no picture change in the next frame Frame2, Vint1N is switched back to Vint1 in the non-display area.

[0055] When the second reset module 4 writes the second reset voltage (recorded as Vint2), the display screen of the next frame is detected in advance in the non-display area. If the screen is not updated, Vint2 is not changed (the previous frame is recorded as Frame0, and the current frame is recorded as Frame1), that is, when Frame0=Frame1, the Vint2 voltage is not adjusted. In the previous frame Frame0 screen, the black or low grayscale position is refreshed to a brighter grayscale screen in the current frame Frame1, so Vint2 is adjusted in the non-display area of ​​the two frames, and Vint2 is adjusted to a more correct value, that is, the second compensation reset voltage (recorded as Vint2P), Vint2<Vint2P. In order to increase the overall voltage of the anode of the organic light-emitting display device, it can be regarded as a pre-charging effect, so that the color mode does not require such a large current to make the organic light-emitting display device emit light. If there is no picture change in the next frame Frame2, Vint2P is switched back to Vint2 in the non-display area.

[0056] The module block diagram for implementing this method is as follows Figure 6As shown, the right block diagram is a circuit of the panel display driving unit 1 of the organic light-emitting display device, including a first light-emitting control module 5, a second light-emitting control module 6, a first reset module 3, a second reset module 4 and a data module (Signal in the figure) and a light-emitting module 10. The present invention adjusts the input voltage of the reset module between frames, and the adjustment voltage is achieved through a peripheral driving circuit 2 (such as a display driver IC internal module). The left block diagram is a schematic diagram of the peripheral driving circuit 2, including a picture detection module 7, a first compensation driving module 8 and a second compensation driving module 9.

[0057] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0058] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for improving low grayscale response time of an organic light emitting display device, wherein the organic light emitting display device comprises at least one panel display driving unit, wherein the panel display driving unit comprises a first reset module and a second reset module, wherein the first reset module is used to provide a first reset voltage in an initialization phase, and the second reset module is used to provide a second reset voltage in a display data writing phase, wherein: The steps are as follows: Step S1: Determine whether the grayscale values ​​of the previous frame and the current frame meet the preset compensation conditions. The compensation condition is specifically: the grayscale value of the previous frame is the lowest or lower than a preset low grayscale threshold, and the grayscale value of the current frame is higher than that of the previous frame; Step S2-1: When the compensation condition is met, adjusting the first reset module to change the first reset voltage to a preset first compensation reset voltage, and adjusting the second reset module to change the second reset voltage to a preset second compensation reset voltage; Step S2-2: When the compensation condition is not met, the first reset module maintains or resumes providing the first reset voltage, and the second reset module maintains or resumes providing the second reset voltage.

2. The method for improving low grayscale response time of an organic light emitting display device according to claim 1, characterized in that: Before step S1, a peripheral driving circuit is arranged in the panel display driving unit, wherein the peripheral driving circuit comprises a picture detection module, a first compensation driving module and a second compensation driving module; The first compensation driving module and the second compensation driving module are electrically connected to the picture detection module respectively; The first compensation driving module is electrically connected to the first reset module; The second compensation driving module is electrically connected to the second reset module; The picture detection module is used to execute step S1; The first compensation driving module is used to adjust the first reset module so that the first reset voltage changes to the first compensation reset voltage, and the second compensation driving module is used to adjust the second reset module so that the second reset voltage changes to the second compensation reset voltage.

3. The method for improving low grayscale response time of an organic light emitting display device according to claim 1, characterized in that: The first compensation reset voltage is lower than the first reset voltage, and the second compensation reset voltage is higher than the second reset voltage.

4. The method for improving low grayscale response time of an organic light emitting display device according to claim 1, characterized in that: The difference between the first reset voltage and the first compensation reset voltage is less than 0.5V.

5. The method for improving low grayscale response time of an organic light emitting display device according to claim 1, characterized in that: The second compensation reset voltage is lower than the sum of the common ground voltage of the panel display driving unit and the start-up voltage of the organic light emitting display device.

6. The method for improving low grayscale response time of an organic light emitting display device according to claim 2, characterized in that: The control signal timing of the organic light-emitting display device has a display area and a non-display area. When the compensation condition is met, the picture detection module adjusts the first reset module through the first compensation driving module in the non-display area of ​​the current frame so that the first reset voltage changes to a preset first compensation reset voltage, and adjusts the second reset module through the second compensation driving module in the non-display area of ​​the current frame so that the second reset voltage changes to a preset second compensation reset voltage.

7. An organic light emitting display device for improving low grayscale response time, which adopts a method for improving low grayscale response time of an organic light emitting display device as claimed in claim 1, characterized in that: It comprises at least one panel display driving unit, wherein the panel display driving unit comprises a peripheral driving circuit, a first reset module and a second reset module; The peripheral driving circuit includes a picture detection module, a first compensation driving module and a second compensation driving module; The first compensation driving module and the second compensation driving module are electrically connected to the picture detection module respectively; The first compensation driving module is electrically connected to the first reset module; The second compensation driving module is electrically connected to the second reset module; The picture detection module is used to execute step S1; The first compensation driving module is used to adjust the first reset module so that the first reset voltage changes to the first compensation reset voltage, and the second compensation driving module is used to adjust the second reset module so that the second reset voltage changes to the second compensation reset voltage.

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