Display panel driving method and display device

Abstract

Disclosed are a display panel driving method and a display device. The display device performs dimming according to the display panel driving method. When the display grayscale is lower than a set threshold, the first driving signal is adjusted to a second driving signal to provide the amplitude of the driving current, improve the anti-interference ability of the driving current, and reduce the pulse frequency of the driving current to ensure that the power output of the driving current to the light-emitting drive remains basically unchanged, and the display brightness remains basically unchanged. The display panel driving method and the display device of the present invention effectively improve the anti-interference ability of the driving current during low grayscale display and improve the dimming accuracy.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a driving method of a display panel and a display device. Background Art

[0002] The backlight source of the display device is generally an LED (light emitting diode). The display brightness can be adjusted by adjusting the light emitting brightness of the LED to achieve grayscale brightness adjustment.

[0003] Among them, the dimming technology of light emitting diodes can be roughly divided into two categories: PWM (Pulse Width Modulation) pulse width dimming and PAM (Pulse Amplitude Modulation) pulse amplitude dimming.

[0004] Pulse width dimming adjusts the LED brightness by converting grayscale data into the high and low level duty ratio of the LED conduction signal pulse. The higher the ratio of conduction time to non-conduction time per unit time, that is, the larger the pulse width, the greater the average current per unit time, and the higher the LED display brightness, and vice versa.

[0005] Pulse amplitude dimming, also known as current dimming, is a method of adjusting the brightness of the LED by changing the current in the LED circuit to change the pulse amplitude of the driving current received by the LED. The larger the conduction current, the higher the pulse amplitude, and vice versa.

[0006] In pulse amplitude dimming, the smaller the grayscale data, the smaller the pulse amplitude of the LED driving current. However, the low current has poor anti-interference ability, which makes the LED driving current easily affected by any small fluctuations caused by devices or wiring in the LED circuit, reducing the accuracy of current dimming. Summary of the invention

[0007] In view of the above problems, an object of the present invention is to provide a driving method and a display device of a light emitting diode display panel, so as to improve the dimming reliability of pulse amplitude dimming at low gray scales and improve the current dimming accuracy.

[0008] According to one aspect of the present invention, there is provided a method for driving a display panel, comprising: acquiring a picture to be displayed of the display panel, and determining a brightness to be displayed of each pixel according to the picture to be displayed; confirming a display grayscale corresponding to each pixel according to the display brightness of each pixel; confirming a first drive signal according to the display grayscale, and driving each pixel according to the first drive signal; and, comparing the display grayscale with a set threshold; when the display grayscale is less than or equal to the set threshold, determining a second drive signal corresponding to the display grayscale, and driving each pixel according to the second drive signal, wherein the amplitude of the second drive signal corresponding to the same display grayscale is greater than the amplitude of the corresponding first drive signal, and the frequency of the second drive signal corresponding to the same display grayscale is less than the frequency of the corresponding first drive signal.

[0009] Optionally, the second driving signal and the first driving signal corresponding to the same display gray scale have the same integrated area in one display driving cycle.

[0010] Optionally, the frequencies of the first drive signal and the second drive signal are obtained according to the product of the number of groups corresponding to the group signal and the frequency of the vertical synchronization signal; and the frequencies of the first drive signal and the second drive signal are adjusted by adjusting the group signal and the number of groups corresponding to the group signal.

[0011] Optionally, the current amplitudes of the first drive signal and the second drive signal are generated by a digital-to-analog converter.

[0012] Optionally, the step of determining the second drive signal corresponding to the display grayscale includes: adjusting the ratio of the amplitude of the second drive signal corresponding to the same display grayscale to the amplitude of the corresponding first drive signal according to a preset ratio to obtain the second drive signal.

[0013] Optionally, the step of determining the second drive signal corresponding to the display grayscale also includes: gradually increasing the ratio of the amplitude of the second drive signal corresponding to the same display grayscale to the amplitude of the corresponding first drive signal according to a preset ratio; after each adjustment, comparing the frequency of the second drive signal with a preset frequency minimum threshold; when the frequency of the second drive signal is less than the preset frequency minimum threshold, ending the adjustment of the second drive signal and outputting the adjusted second drive signal.

[0014] Optionally, after a single adjustment, the amplitude of the second driving signal is twice that before the adjustment, and the frequency of the second driving signal is half that before the adjustment.

[0015] Optionally, the display panel comprises a light emitting diode array;

[0016] According to another aspect of the present invention, a dimming module is provided for use in any of the above display panel driving methods to control the light emitting brightness of each LED of the LED array, wherein the LEDs correspond to pixels one by one.

[0017] Optionally, the dimming module includes: a pulse amplitude dimming module, which is used to adjust the amplitude of the driving current provided to each LED of the LED array according to the input grayscale data, so as to adjust the luminous brightness of each LED of the LED array; a pulse width dimming module, which is used to adjust the pulse width of the driving current of each LED of the LED array according to the input grayscale data, so as to adjust the luminous brightness of each LED of the LED array, wherein the dimming module also selects dimming by adjusting the amplitude or pulse width of the driving current according to the dimming mode control instruction, and when dimming is selected by adjusting the pulse width of the driving current, the amplitude of the driving current is fixed, and when dimming is selected by adjusting the amplitude of the driving current, the pulse width of the driving current is fixed.

[0018] Optionally, the light emitting diode array includes any one of a mini light emitting diode, a micro light emitting diode, a quantum dot light emitting diode, and an organic light emitting diode.

[0019] According to another aspect of the present invention, a terminal device is provided, wherein the terminal device comprises the above-mentioned display apparatus.

[0020] The driving method of the display panel provided by the present invention increases the amplitude of the driving current and improves the anti-interference ability of the driving current when the display grayscale of the pixel is lower than the set threshold, and at the same time reduces the pulse frequency of the driving current to ensure that the output power of the driving current remains basically unchanged, and the luminous brightness of the light-emitting diode is maintained basically unchanged, thereby effectively improving the anti-interference ability of the driving current during low grayscale display and improving the dimming accuracy.

[0021] The display device provided by the present invention includes a display panel and a dimming module. The display panel includes a light-emitting diode array. The dimming module controls the luminous brightness of each light-emitting diode in the light-emitting diode array according to the driving method of the display panel of the present invention, increases the pulse amplitude of the driving current at low gray scales, and reduces the pulse frequency of the driving current. While maintaining the power of the driving current output to the light-emitting diode basically unchanged, the increase in the pulse amplitude effectively improves the anti-interference ability of the driving current, thereby improving the dimming accuracy of the low gray scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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:

[0023] Figure 1 A flow chart showing a method for driving a display panel according to an embodiment of the present invention is shown;

[0024] Figure 2 The schematic diagram of the current pulse width control principle in the driving method of the display panel according to the embodiment of the present invention is shown;

[0025] Figure 3 The figure shows a schematic diagram of the pulse frequency regulation principle of the display panel driving method according to the embodiment of the present invention;

[0026] Figure 4 A schematic diagram showing the state regulation of the driving current of the driving method of the display panel according to the embodiment of the present invention is shown;

[0027] Figure 5 shows an input-output curve of a digital-to-analog converter of a display panel driving method according to an embodiment of the present invention;

[0028] Figure 6 A curve showing a change in driving current versus gray scale of a display panel driving method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0029] 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, the same elements are represented by the same or similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0030] The specific implementation of the present invention is further described in detail below in conjunction with the drawings and examples.

[0031] Figure 1 A flow chart of a method for driving a display panel according to an embodiment of the present invention is shown.

[0032] Reference Figure 1 The display panel driving method of this embodiment is used for a display device, which is provided with a light emitting diode array for providing a backlight source. The brightness of each light emitting diode in the light emitting diode array can be adjusted according to the grayscale data of the corresponding pixel. The light emitting diode corresponds to the pixel one by one. In an optional embodiment, the light emitting diode corresponds to multiple pixel areas, that is, the present invention can also be used for regional dimming. In this embodiment, the display device is provided with a pulse width dimming module and a pulse amplitude dimming module at the same time, and the display panel driving method thereof includes:

[0033] Step S10: Determine whether current dimming is used, that is, determine whether to select pulse width dimming mode or pulse amplitude dimming mode according to the dimming mode control instruction.

[0034] According to the dimming mode selection, in the pulse width dimming mode, step S20 is performed: the amplitude of the driving current of the light emitting diode is fixed, and the backlight brightness is adjusted by adjusting the duty cycle of the pulse width modulation signal.

[0035] In this embodiment, the current source of the driving current is a digital-to-analog converter. In step S20, the amplitude of the output current of the digital-to-analog converter is also fixed to a maximum value.

[0036] In the pulse amplitude dimming mode, step S30 is performed: the pulse width of the pulse width modulation signal is controlled to remain unchanged, and the backlight brightness is adjusted by adjusting the amplitude of the driving current.

[0037] In step S30, the digital-to-analog converter adjusts the output current according to the input grayscale data, thereby controlling the amplitude of the driving current.

[0038] Step S40, determining whether the input grayscale data is low grayscale data.

[0039] In step S40, the input grayscale data is compared with the preset low grayscale data. When the input grayscale data is less than or equal to the preset low grayscale data, step S50 is performed; when the input grayscale data is greater than the preset low grayscale data, the control process is terminated and the backlight is driven according to the output current of the current digital-to-analog converter.

[0040] In a specific embodiment, the preset low grayscale data is, for example, 10% of the maximum grayscale, but the specific selection can be determined according to actual needs and will not be described in detail herein.

[0041] Step S50: increasing the amplitude of the driving current and reducing the pulse frequency of the driving current.

[0042] In step S50, the amplitude of the driving current is increased to improve the anti-interference ability of the driving current, while the pulse frequency of the driving current is reduced so that the equivalent driving force of the driving current per unit time remains unchanged. Without changing the luminous brightness of the light-emitting diode, the anti-interference ability of the current dimming is improved and the accuracy of the current dimming is improved.

[0043] In this embodiment, after a single adjustment, the amplitude of the driving current is twice that before the adjustment, and the pulse frequency of the driving current is half that before the adjustment. Correspondingly, the preset low grayscale data is, for example, half of the maximum grayscale. When the input grayscale data is half of the maximum grayscale, the amplitude of the original driving current before the adjustment is half of the maximum output amplitude of the digital-to-analog converter. The amplitude of the driving current after the adjustment is adjusted to the maximum output amplitude of the digital-to-analog converter. The amplitude of the driving current can be maximized through one cycle, thereby maximizing the anti-interference ability of the driving current. In specific applications, the single adjustment amount of the amplitude and pulse frequency of the driving current is selected according to specific needs. For example, the amplitude is 1.5 times that before the adjustment, and the pulse frequency is 0.67 times that before the adjustment. The overall guarantee is that the output power of the driving current per unit time remains unchanged, the corresponding luminous driving force of the light-emitting diode per unit time remains unchanged, and the luminous brightness of the light-emitting diode remains unchanged. While maintaining the original luminous brightness, the anti-interference ability of the driving current is improved.

[0044] In this embodiment, the refresh of input grayscale data (the number is consistent with the pixels, and a group of input grayscale data corresponds to the brightness information of each pixel of a frame of the display screen) is controlled according to the vertical synchronization signal, and a frame of grayscale data is refreshed at the end of each cycle of the vertical synchronization signal to control the picture display frame rate.

[0045] The product of the frequency of the vertical synchronization signal and the corresponding number of groups of the group signal is used as the pulse frequency of the driving current (corresponding to the first driving signal before adjustment, corresponding to the second driving signal after adjustment, and the frequencies of the first driving signal and the second driving signal both correspond to this operation). By adjusting the number of groups corresponding to the group signal, the pulse frequency of the driving current can be adjusted.

[0046] That is, the driving method of the display panel of the present invention includes: obtaining the picture to be displayed of the display panel, and determining the brightness to be displayed of each pixel according to the picture to be displayed; confirming the display grayscale corresponding to each pixel according to the display brightness of each pixel; confirming the first driving signal according to the display grayscale, and driving each pixel according to the first driving signal; and comparing the display grayscale with a set threshold; when the display grayscale is less than or equal to the set threshold, determining the second driving signal corresponding to the display grayscale, and driving each pixel according to the second driving signal. Wherein, the amplitude of the second driving signal corresponding to the same display grayscale is greater than the amplitude of the corresponding first driving signal, and the frequency of the second driving signal corresponding to the same display grayscale is less than the frequency of the corresponding first driving signal.

[0047] Step S60: Determine whether the pulse frequency of the driving current reaches a predetermined target.

[0048] In step S60, the pulse frequency of the adjusted driving current is compared with a preset minimum standard, wherein the standard is the frequency threshold of the second driving signal. When the pulse frequency of the adjusted driving current is less than or equal to the preset minimum standard, it is considered that the predetermined target is achieved, and the adjustment is terminated. The backlight driving is performed according to the amplitude and pulse frequency of the driving current after this adjustment. When the pulse frequency of the adjusted driving current is greater than the preset minimum standard, it is considered that the amplitude of the driving current can be further increased, and the pulse frequency of the driving current can be further reduced. The cycle of steps S40, S50, and S60 is continued to be executed, so that a higher amplitude of the driving current can be obtained and the anti-interference capability can be improved.

[0049] The frequency of the vertical synchronization signal may fluctuate to a certain extent according to the actual use of the display device. By performing the judgment in step S60 and detecting the pulse frequency of the driving current, it is possible to effectively prevent the pulse frequency of the driving current from being configured to a lower value when the frequency of the vertical synchronization signal is lower, thereby ensuring that the driving current can effectively output a certain power and ensure the light-emitting drive of the LED.

[0050] Figure 2 The figure shows the principle of current pulse width control in the driving method of the display panel according to the embodiment of the present invention.

[0051] Reference Figure 2 The output current provided by the digital-to-analog converter adjusts the pulse width according to the pulse width modulation signal PWM, and the pulse width and frequency of the obtained first current I1 are consistent with the pulse width and frequency of the pulse width modulation signal PWM. By fixing the pulse width and frequency of the pulse width modulation signal PWM, the pulse width and frequency of the first current I1 can be fixed. When the amplitude of the output current of the digital-to-analog converter decreases with the grayscale data gray, the pulse amplitude of the first current I1 can be reduced accordingly.

[0052] Figure 3 The figure shows a schematic diagram of the pulse frequency regulation principle of the display panel driving method according to the embodiment of the present invention.

[0053] Reference Figure 3 , in the order of GRP64, GRP32, GRP16, ..., GRP1, as the number of groups decreases, the pulse frequency of the group signal decreases successively.

[0054] The frequency reduction is for example based on Figure 2 The maximum frequency of the first current I1 is shown as a basic quantity, and a switch is added to its output path. The switch is controlled according to the group signal GRP.

[0055] Figure 4 A schematic diagram showing state regulation of a driving current in a driving method for a display panel according to an embodiment of the present invention is shown.

[0056] Reference Figure 4 , while the amplitude of the second current I2 increases, the frequency decreases. Within a certain period of time, the second current I2 is integrated in time, and its integral area is consistent. Even if the second drive signal and the first drive signal corresponding to the same display grayscale have the same integral area in a display drive cycle, the driving force and brightness of the light-emitting diode are consistent before and after adjustment, and the increase in amplitude effectively improves its anti-interference ability.

[0057] Figure 5 The input and output curves of the digital-to-analog converter of the display panel driving method according to the embodiment of the present invention are shown.

[0058] Reference Figure 5 , the actual amplitude of the output current I0 of the digital-to-analog converter corresponds to the segmented curve in the A1 area (corresponding to the amplitude of the first drive signal). When the input grayscale data is less than the low grayscale data g0, the actual output amplitude of the output current of the digital-to-analog converter (corresponding to the amplitude of the second drive signal, corresponding to the curve in the A2 area) is greater than the original output amplitude (curve in the B area, corresponding to the amplitude of the first drive signal).

[0059] In a specific embodiment, a first controller is provided, and a conversion configuration of the digital-to-analog converter is adjusted according to the first controller. When the input grayscale data is less than or equal to the low grayscale data, the ratio of the output current amplitude of the digital-to-analog converter to the input grayscale data is increased (corresponding to the slope of the A2 area curve), so as to increase the amplitude of the output current of the digital-to-analog converter when the input grayscale data is less than the low grayscale data.

[0060] Among them, the first driving signal is obtained according to the original grayscale-current correspondence. When the displayed grayscale is less than or equal to the preset threshold, based on the first driving signal, the ratio of the amplitude of the second driving signal corresponding to the same displayed grayscale to the amplitude of the corresponding first driving signal is adjusted according to the preset ratio to obtain the second driving signal. In this embodiment, the preset ratio of the amplitude is twice, and the preset ratio of the frequency is one-half.

[0061] In this embodiment, multiple adjustments are made according to the preset ratio and the first driving signal, and step S60 is also executed after each adjustment to avoid the pulse frequency of the driving current being configured to a lower value when the frequency of the vertical synchronization signal is low, thereby ensuring that the driving current can effectively output a certain power and ensure the light-emitting drive of the LED.

[0062] Figure 6 A curve showing a change in driving current versus gray scale of a display panel driving method according to an embodiment of the present invention is shown.

[0063] Reference Figure 6In this embodiment, the driving current received by the light-emitting diode is tested. As the grayscale data changes linearly, the output power of the driving current also changes linearly. The luminous brightness of the corresponding light-emitting diode changes linearly with the input grayscale data. That is, the driving method of the display panel of the embodiment of the present invention can ensure the corresponding relationship between the luminous brightness of the light-emitting diode and the input grayscale data, ensure the dimming accuracy, and improve the anti-interference ability of the driving current at low brightness, further improving the dimming accuracy at low grayscale data.

[0064] In one embodiment, 96 channels of mini LEDs are dimmed, each channel uses 14-bit grayscale and 7-bit current dimming, can adapt to 30Hz to 1000Hz dynamic refresh rate, and can achieve an actual display refresh rate of up to 15K through the configured group display solution, with a peak current of 1 to 30mA.

[0065] It should be noted that, in addition to mini LED, the present invention can also be applied to any one of micro light-emitting diodes (MircoLED), quantum dot light-emitting diodes (Quantum Dot Light Emitting Diodes, QLED), and organic light-emitting diodes (Organic Light-Emitting Diode, OLED).

[0066] The driving method of the display panel provided by the present invention increases the amplitude of the driving current and the anti-interference ability of the driving current when the input grayscale data is a low grayscale, and at the same time reduces the pulse frequency of the driving current, thereby ensuring that the power output of the driving current to the light-emitting drive remains basically unchanged, maintaining the display brightness basically unchanged, effectively improving the anti-interference ability of the driving current during low grayscale display, and improving the dimming accuracy.

[0067] The present invention also provides a display device, including a display panel and a dimming module, the display panel includes a light-emitting diode array, the dimming module includes a pulse amplitude dimming module and a pulse width dimming module, the pulse amplitude dimming module is used to adjust the pulse amplitude of the driving current of the light-emitting diode, the pulse width dimming module is used to adjust the pulse width of the driving current of the light-emitting diode, the dimming module controls the luminous brightness of each light-emitting diode in the light-emitting diode array according to the driving method of the display panel of the present invention, increases the pulse amplitude of the driving current at low gray scale, and reduces the pulse frequency of the driving current at the same time, while maintaining the power of the driving current output to the light-emitting diode basically unchanged, the pulse amplitude improves the anti-interference ability of the driving current, thereby improving the dimming accuracy of the low gray scale.

[0068] The present invention also provides a terminal device, on which the above-mentioned display device is installed. Specifically, the terminal device can be any one of a smart phone, a car computer, a tablet computer, a laptop computer, a smart wearable electronic device, an advertising billboard, etc., and the present invention does not limit this.

[0069] According to the embodiments of the present invention as described above, these embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes 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 the modified use based on the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for driving a display panel, comprising: Acquire a picture to be displayed of the display panel, and determine the brightness to be displayed of each pixel according to the picture to be displayed; Determine the display grayscale corresponding to each pixel according to the display brightness of each pixel; Determining a first driving signal according to the display grayscale, and driving each pixel according to the first driving signal; as well as, comparing the displayed grayscale with a set threshold; adjusting the ratio of the amplitude of the second driving signal corresponding to the same display grayscale to the amplitude of the corresponding first driving signal in multiple times according to a preset ratio; After each adjustment, comparing the frequency of the second driving signal with a preset frequency minimum threshold; When the frequency of the second driving signal is less than the preset frequency minimum threshold, the adjustment of the second driving signal is terminated, and the adjusted second driving signal is output, and each pixel is driven according to the second driving signal, wherein: The amplitude of the second driving signal corresponding to the same display gray scale is greater than the amplitude of the corresponding first driving signal, and the frequency of the second driving signal corresponding to the same display gray scale is less than the frequency of the corresponding first driving signal.

2. The method for driving a display panel according to claim 1, wherein: The second driving signal and the first driving signal corresponding to the same display grayscale have the same brightness of each pixel in one display driving cycle.

3. The method for driving a display panel according to claim 1, wherein: Also includes: Obtaining the frequencies of the first drive signal and the second drive signal according to the product of the number of groups corresponding to the group signal and the frequency of the vertical synchronization signal; By adjusting the group signal, the number of groups corresponding to the group signal is adjusted to adjust the frequencies of the first driving signal and the second driving signal.

4. The method for driving a display panel according to claim 1, wherein: Also includes: The current amplitudes of the first driving signal and the second driving signal are generated by a digital-to-analog converter.

5. The method for driving a display panel according to claim 2, wherein: The step of determining the second driving signal corresponding to the display grayscale includes: The ratio of the amplitude of the second driving signal corresponding to the same display gray scale to the amplitude of the corresponding first driving signal is adjusted according to a preset ratio to obtain the second driving signal.

6. The method for driving a display panel according to claim 1, wherein: After a single adjustment, the amplitude of the second driving signal is twice that before the adjustment, and the frequency of the second driving signal is half that before the adjustment.

7. A display device, comprising: A display panel including an array of light emitting diodes; A dimming module, used for controlling the light emitting brightness of each light emitting diode of the light emitting diode array according to the driving method of the display panel according to any one of claims 1 to 6, wherein the light emitting diodes correspond to pixels one by one.

8. The display device according to claim 7, wherein: The dimming module comprises: A pulse amplitude dimming module, used for adjusting the amplitude of the driving current provided to each light emitting diode of the light emitting diode array according to the input grayscale data, so as to adjust the light emitting brightness of each light emitting diode of the light emitting diode array; A pulse width dimming module is used to adjust the pulse width of the driving current of each light emitting diode of the light emitting diode array according to the input grayscale data, so as to adjust the light emitting brightness of each light emitting diode of the light emitting diode array, The dimming module further selects to dim the light by adjusting the amplitude or pulse width of the driving current according to the dimming mode control instruction. When dimming is performed by adjusting the pulse width of the driving current, the amplitude of the driving current is fixed. When dimming is performed by adjusting the amplitude of the driving current, the pulse width of the driving current is fixed.

9. The display device according to claim 7, wherein: The light emitting diode array includes any one of a light emitting diode, a micro light emitting diode, a quantum dot light emitting diode, and an organic light emitting diode.

10. A terminal device, wherein: The terminal device comprises the display apparatus according to claim 7.

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