Driving method, circuit and AMOLED display screen

Abstract

The invention discloses a driving method and circuit and an AMOLED display screen, and the method comprises the steps: providing a driving circuit which comprises a control module, a TFT driving module, a PWM module and a light-emitting diode, the TFT driving module and the PWM module are electrically connected with the control module, the TFT driving module is electrically connected with the PWM module, and the PWM module is electrically connected with the light-emitting diode; the control module is used for obtaining the gray scale of the to-be-displayed picture, and the duty ratio of the pulse signal output by the PWM module is reversely adjusted according to the gray scale of the to-be-displayed picture; and the PWM module outputs a pulse signal according to the duty ratio, and adjusts the magnitude of the current output to the light emitting diode so as to obtain the brightness of the corresponding gray scale. Under the condition that the brightness requirement is met, the brightness of each gray scale is uniformly controlled, the problems that the low-darkness display effect is poor and the black color of the whole AMOLED screen is not uniform are solved, and meanwhile the problem of high power consumption of an existing compensation circuit is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of AMOLED display screen brightness control, and in particular to a driving method, a circuit and an AMOLED display screen. Background Art

[0002] AMOLED has bright display effects, high contrast and small screen, and is widely used in smart watch projects. Smart watches have more and more comprehensive functions, integrating a series of functions such as touch, display, NFC payment, etc. AMOLED is a self-luminous display, which is different from TFT modules that need backlight to emit light. However, some consumers have reported that when using AMOLED display modules in dark environments, the brightness of AMOLED displays under black screens is still relatively high, and the effect of low darkness cannot be reflected. Sometimes you can also see the uneven surface display effect of AMOLED at low brightness.

[0003] The main reason is that due to the limitations of the crystallization process, LTPS-TFTs made on large-area glass substrates often have non-uniform electrical parameters such as threshold voltage and mobility in different positions of TFTs. This non-uniformity will be converted into current differences and brightness differences in OLED display devices and perceived by the human eye. As a result, when we use low current to control AMOLED to display low grayscale (close to black brightness), due to differences in display panels, etc., the black at this time will not be black, or the black of the entire AMOLED screen will be uneven. Summary of the invention

[0004] The existing AMOLED display screen has the problems of poor low-darkness display effect and uneven black color of the entire AMOLED screen when using low current to control the AMOLED to display low grayscale images.

[0005] In view of the above problems, a driving method, circuit and AMOLED display are proposed. By reversely adjusting the duty cycle of the pulse signal output by the PWM module according to the gray scale of the picture to be displayed, and outputting the pulse signal according to the duty cycle, the driving current output to the light-emitting diode is adjusted, thereby achieving uniform control of the brightness of each gray scale while meeting the brightness requirements, solving the problems of poor low-darkness display effect and uneven black color of the entire AMOLED screen, and avoiding the high power consumption problem of the existing compensation circuit.

[0006] In a first aspect, a driving method includes: Step 100, providing a driving circuit, including a control module, a TFT driving module, a PWM module and a light emitting diode, wherein the TFT driving module and the PWM module are electrically connected to the control module respectively, the TFT driving module is electrically connected to the PWM module, and the PWM module is electrically connected to the light emitting diode; Step 200: using the control module to obtain the grayscale of the picture to be displayed, and reversely adjusting the duty cycle of the pulse signal output by the PWM module according to the grayscale of the picture to be displayed; Step 300: The PWM module outputs a pulse signal according to the duty cycle to adjust the current output to the light emitting diode to obtain a brightness corresponding to the gray scale.

[0007] In combination with the driving method of the present invention, in a first possible implementation manner, step 200 includes: Step 210, obtaining the total number of gray levels of the display image; Step 220: Divide the pulse period of the pulse signal according to the total number of gray levels to obtain equal fractions of the pulse period.

[0008] In combination with the first possible implementation manner of the present invention, in a second possible implementation manner, step 200 further includes: Step 230, obtaining the current grayscale number of the image to be displayed; Step 240, obtaining a grayscale ratio of the current grayscale number to the total number of grayscales; Step 250, obtaining a grayscale difference ratio according to the grayscale ratio; The grayscale difference ratio is a difference between 1 and the grayscale ratio.

[0009] In combination with the second possible implementation manner of the present invention, in a third possible implementation manner, step 200 further includes: Step 260, obtaining the grayscale difference ratio; Step 270: Use the grayscale differential ratio as the duty cycle of the pulse signal to control the output of the PWM module.

[0010] In a second aspect, a driving circuit is driven by the driving method described in the first aspect, comprising: Control module, TFT drive module, PWM module and light emitting diode; The TFT driving module and the PWM module are electrically connected to the control module respectively, the TFT driving module is electrically connected to the PWM module, and the PWM module is electrically connected to the light emitting diode; The TFT driving module is used for the control module to instruct output of driving current; The PWM module is used to output a pulse signal corresponding to the duty cycle according to the instruction of the control module to adjust the size of the driving circuit; The control module is used to obtain the gray scale of the picture to be displayed, and reversely adjust the duty cycle of the pulse signal output by the PWM module according to the gray scale of the picture to be displayed.

[0011] In combination with the driving circuit described in the second aspect of the present invention, in a first possible implementation manner, the TFT driving module includes: A first transistor, a second transistor, and a capacitor; The gate of the first transistor is electrically connected to the scan line, the source is electrically connected to the data line, and the drain is electrically connected to the first end of the capacitor and the gate of the second transistor; The source of the second transistor is electrically connected to the driving current input terminal and the second end of the capacitor, and the drain of the second transistor is electrically connected to the input terminal of the PWM module.

[0012] In combination with the first possible implementation manner of the second aspect of the present invention, in a second possible implementation manner, the control module is further used to: The total number of grayscales of the display screen is obtained, and the pulse period of the pulse signal is divided according to the total number of grayscales to obtain equal fractions of the pulse period.

[0013] In conjunction with the second possible implementation manner of the second aspect of the present invention, in a third possible implementation manner, the control module is further used for: Obtaining a current grayscale number of a picture to be displayed, obtaining a grayscale ratio of the current grayscale number to the total number of grayscales, and obtaining a grayscale difference ratio according to the grayscale ratio; The grayscale difference ratio is a difference between 1 and the grayscale ratio.

[0014] In combination with the third possible implementation manner of the second aspect of the present invention, in a fourth possible implementation manner, the control module is further used for: The grayscale differential ratio is obtained, and the grayscale differential ratio is used as the duty cycle of the pulse signal to control the output of the PWM module.

[0015] In a third aspect, an AMOLED display screen includes the driving circuit described in the second aspect, wherein a plurality of the driving circuits constitute an array circuit of the AMOLED display screen to drive each pixel.

[0016] The driving method, circuit and AMOLED display screen described in the present invention are implemented by reversely adjusting the duty cycle of the pulse signal output by the PWM module according to the gray scale of the picture to be displayed, and outputting the pulse signal according to the duty cycle, thereby adjusting the driving current output to the light-emitting diode, thereby achieving uniform control of the brightness of each gray scale while meeting the brightness requirements, solving the problems of poor low-darkness display effect and uneven black color of the entire AMOLED screen, and avoiding the high power consumption problem of the existing compensation circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the scheme in the present application, a brief introduction is given below to the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 is a schematic diagram of an AMOLED display screen in the prior art; Figure 2 It is a structural schematic diagram of a sub-pixel driving circuit of an AMOLED display screen in the prior art; Figure 3 is a schematic structural diagram of a sub-pixel driving circuit of an AMOLED display screen in the present application; Figure 4 It is a schematic diagram of equally dividing the pulse period of the pulse signal in this application; Figure 5 is a flowchart of a specific implementation of a driving method in the present application; Figure 6 yes Figure 5 A flowchart of a specific implementation of S200; Figure 7 yes Figure 6 A flowchart of a specific implementation method after S220; Figure 8 yes Figure 7 A flowchart of a specific implementation method after S250; Fig. 9 This is a module structure diagram of an AMOLED display screen in this application. DETAILED DESCRIPTION

[0019] The following will be combined with the accompanying drawings in the invention to clearly and completely describe the technical solutions in 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 in the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0020] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0022] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0023] Name Explanation AMOLED: Active Matrix Organic Light Emitting Diode SCAN: Scan DATA: Data line PWM: Pulse Width Modulation TFT: Thin Film Transistor Existing AMOLED displays, such as Figure 1 , Figure 1 It is a schematic diagram of an AMOLED display screen in the prior art; when a low current is used to control the AMOLED to display a low grayscale image, there are problems such as poor low-darkness display effect and uneven black on the entire AMOLED screen.

[0024] In the prior art, each pixel is driven by its own driving circuit, and each pixel is controlled by its own TFT tube.

[0025] like Figure 2 , Figure 2 It is a structural diagram of the sub-pixel driving circuit of the AMOLED display screen in the prior art; when the scan signal (SCAN signal) is valid, T1 will be turned on, and the data line DATA voltage will start T2 to turn on, so that T2 will generate Id current. The brightness of the light-emitting diode is determined by the current flowing through the OLED light-emitting diode itself. The larger the current, the higher the brightness, and vice versa, the smaller the current, the lower the brightness.

[0026] However, due to the limitations of the crystallization process, LTPS TFTs made on large-area glass substrates often have non-uniform electrical parameters such as threshold voltage and mobility at different locations. This non-uniformity will be converted into current differences and brightness differences in OLED display devices and will be perceived by the human eye. This results in the black not being black at this time or uneven black on the entire AMOLED screen due to differences in the panel and other factors when we use low current to control the AMOLED to display low grayscale (close to black brightness).

[0027] In the existing technology, more compensation circuits are introduced to solve this problem, such as 6T1C or 7T1C, etc., which enables AMOLED to achieve the effect required by customers in low grayscale (close to black brightness) images. However, due to the introduction of multiple circuits, this will greatly occupy the AMOLED light-emitting area, reduce the AMOLED aperture ratio, and require a higher current when the AMOLED needs to maintain a certain brightness, thereby producing more energy consumption, accelerating the aging of the AMOLED, and shortening the life of the AMOLED.

[0028] In view of the above problems, a driving method, a circuit and an AMOLED display screen are proposed.

[0029] In the first aspect, a driving method, such as Figure 5 , Figure 5 It is a flowchart of a specific implementation of a driving method in this application; it includes: Step 100, providing a driving circuit, including a control module, a TFT driving module, a PWM module and a light emitting diode, wherein the TFT driving module and the PWM module are electrically connected to the control module respectively, the TFT driving module is electrically connected to the PWM module, and the PWM module is electrically connected to the light emitting diode.

[0030] In this embodiment, three RGB sub-pixels form one pixel, and multiple pixels form the entire AMOLED display screen. Each sub-pixel on the AMOLED display screen is controlled by an independent thin film transistor to achieve the desired light-emitting effect.

[0031] In this embodiment, a control module is used to control the duty cycle of the PWM module, thereby adjusting the magnitude of the driving current output to the light emitting diode to adjust the brightness.

[0032] Step 200: Utilize the control module to obtain the gray scale of the picture to be displayed, and reversely adjust the duty cycle of the pulse signal output by the PWM module according to the gray scale of the picture to be displayed.

[0033] In a preferred embodiment, if Figure 6 , Figure 6 yes Figure 5A flowchart of a specific implementation of S200; step 200 includes: step 210, obtaining the total number of grayscales of the display screen; step 220, dividing the pulse period of the pulse signal according to the total number of grayscales, and obtaining equal fractions of the pulse period.

[0034] In this embodiment, if Figure 3 , Figure 3 It is a structural schematic diagram of the sub-pixel driving circuit of the AMOLED display screen in this application; a duty cycle signal PWM module is introduced to simplify complex circuit compensation.

[0035] In this embodiment, if Figure 4 , Figure 4 It is a schematic diagram of equally dividing the pulse period of the pulse signal in the present application; the pulse period is divided into seven equal parts, and the corresponding duty cycles correspond to the 0th gray scale to the 7th gray scale, and the gray scale number decreases from the 0th gray scale to the 7th gray scale, the 0th gray scale is completely black, and the 7th gray scale is fully bright.

[0036] In a preferred embodiment, Figure 7 , Figure 7 yes Figure 6 A flowchart of a specific implementation method after S220; step 200 also includes: step 230, obtaining the current grayscale number of the image to be displayed; step 240, obtaining the grayscale ratio of the current grayscale number to the total grayscale number; step 250, obtaining the grayscale differential ratio according to the grayscale ratio; wherein the grayscale differential ratio is the difference between 1 and the grayscale ratio.

[0037] In this embodiment, the grayscale number and the duty cycle are inversely correlated. When the grayscale number increases, the required duty cycle becomes smaller. Based on this principle, the duty cycle is calculated.

[0038] In a preferred embodiment, Figure 8 , Figure 8 yes Figure 7 A flowchart of a specific implementation method after S250; step 200 also includes: step 260, obtaining the grayscale differential ratio; step 270, using the grayscale differential ratio as the duty cycle of the pulse signal to control the PWM module output.

[0039] For example, the 6 low-brightness gray levels of the lowest gray level (close to black brightness) will cause uneven black screen or abnormal brightness. First, reduce the drive current (Id current) to a level that can stably control the 7th low-brightness gray level of the TFT. At this time, the 7th low brightness can meet the specification requirements, and the uniformity also meets the requirements. At this time, the AMOLED effect is stable and normal.

[0040] The adjustment of the following 6 low-brightness grayscales can be completed by the pulse signal output by the PWM module.

[0041] When the 0th grayscale is completely black, the PWM is pulled to a low level, and the Id current cannot pass, so the AMOLED here displays a completely black screen. Then, when it is the 1st grayscale, 1 is high level, and the other 6 are low level. When it is the 2nd grayscale, 2 are high level, and the other 5 are low level. Similarly, when it is the 6th grayscale, 6 are high level, and the other 1 is low level. If all 7 are high level, it is the 7th low brightness grayscale from the bottom to be displayed at full brightness.

[0042] Step 300, the PWM module outputs a pulse signal according to the duty cycle, and adjusts the current output to the light-emitting diode to obtain the brightness of the corresponding grayscale. By reversely adjusting the duty cycle of the pulse signal output by the PWM module according to the grayscale of the image to be displayed, and outputting the pulse signal according to the duty cycle, and adjusting the drive current output to the light-emitting diode, the brightness of each grayscale is uniformly controlled while meeting the brightness requirements, solving the problems of poor low-darkness display effect and uneven black on the entire AMOLED screen, and avoiding the high power consumption problem of the existing compensation circuit.

[0043] In a second aspect, a driving circuit is driven by the driving method of the first aspect, such as Fig. 9 , Fig. 9 It is a module structure diagram of an AMOLED display screen in the present application. It includes a control module 41, a TFT driving module 42, a PWM module 43 and a light emitting diode 44; the TFT driving module 42 and the PWM module 43 are electrically connected to the control module 41 respectively, the TFT driving module 42 is electrically connected to the PWM module 43, and the PWM module 43 is electrically connected to the light emitting diode 44; the TFT driving module 42 is used to output a driving current according to the instruction of the control module 41; the PWM module 43 is used to output a pulse signal corresponding to the duty cycle according to the instruction of the control module 41 to adjust the size of the driving circuit; the control module 41 is used to obtain the gray scale of the picture to be displayed, and reversely adjust the duty cycle of the pulse signal output by the PWM module 43 according to the gray scale of the picture to be displayed.

[0044] like Figure 3 The TFT driving module 42 includes a first transistor T1, a second transistor T2, and a capacitor; the gate of the first transistor T1 is electrically connected to the scan line, the source is electrically connected to the data line, and the drain is electrically connected to the first end of the capacitor and the gate of the second transistor T2; the source of the second transistor T2 is electrically connected to the driving current input end (ELVDD) and the second end of the capacitor, and the drain is electrically connected to the input end of the PWM module 43.

[0045] Furthermore, the control module 41 is further used to obtain the total number of grayscales of the display image, divide the pulse period of the pulse signal according to the total number of grayscales, and obtain equal fractions of the pulse period.

[0046] Furthermore, the control module 41 is further used to: obtain the current grayscale number of the image to be displayed, obtain the grayscale ratio of the current grayscale number to the total grayscale number, and obtain the grayscale differential ratio according to the grayscale ratio; wherein the grayscale differential ratio is the difference between 1 and the grayscale ratio.

[0047] Furthermore, the control module 41 is further used to obtain the grayscale differential ratio, and use the grayscale differential ratio as the duty cycle of the pulse signal to control the output of the PWM module 43.

[0048] In a third aspect, an AMOLED display screen includes the driving circuit of the second aspect, wherein a plurality of driving circuits constitute an array circuit of the AMOLED display screen to drive each pixel.

[0049] A driving method, circuit and AMOLED display screen of the present invention are implemented. By reversely adjusting the duty cycle of the pulse signal output by the PWM module according to the gray scale of the picture to be displayed, and outputting the pulse signal according to the duty cycle, the driving current output to the light-emitting diode is adjusted, so that the brightness of each gray scale is uniformly controlled while meeting the brightness requirements, and the problems of poor low-darkness display effect and uneven black color of the entire AMOLED screen are solved, while avoiding the high power consumption problem of the existing compensation circuit.

[0050] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A driving method, characterized in that: include: Step 100, providing a driving circuit, including a control module, a TFT driving module, a PWM module and a light emitting diode, wherein the TFT driving module and the PWM module are electrically connected to the control module respectively, the TFT driving module is electrically connected to the PWM module, and the PWM module is electrically connected to the light emitting diode; Step 200: using the control module to obtain the grayscale of the picture to be displayed, and reversely adjusting the duty cycle of the pulse signal output by the PWM module according to the grayscale of the picture to be displayed; Step 300: The PWM module outputs a pulse signal according to the duty cycle to adjust the current output to the light emitting diode to obtain a brightness corresponding to the gray scale.

2. The driving method according to claim 1, characterized in that: The step 200 comprises: Step 210, obtaining the total number of gray levels of the display image; Step 220: Divide the pulse period of the pulse signal according to the total number of gray levels to obtain equal fractions of the pulse period.

3. The driving method according to claim 2, characterized in that: The step 200 further includes: Step 230, obtaining the current grayscale number of the image to be displayed; Step 240, obtaining a grayscale ratio of the current grayscale number to the total number of grayscales; Step 250, obtaining a grayscale difference ratio according to the grayscale ratio; The grayscale difference ratio is a difference between 1 and the grayscale ratio.

4. The driving method according to claim 3, characterized in that: The step 200 further includes: Step 260, obtaining the grayscale difference ratio; Step 270: Use the grayscale differential ratio as the duty cycle of the pulse signal to control the output of the PWM module.

5. A driving circuit, driven by the driving method according to any one of claims 1 to 4, characterized in that: include: Control module, TFT drive module, PWM module and light emitting diode; The TFT driving module and the PWM module are electrically connected to the control module respectively, the TFT driving module is electrically connected to the PWM module, and the PWM module is electrically connected to the light emitting diode; The TFT driving module is used for the control module to instruct output of driving current; The PWM module is used to output a pulse signal corresponding to the duty cycle according to the instruction of the control module to adjust the size of the driving circuit; The control module is used to obtain the gray scale of the picture to be displayed, and reversely adjust the duty cycle of the pulse signal output by the PWM module according to the gray scale of the picture to be displayed.

6. The driving circuit according to claim 5, characterized in that: The TFT driving module comprises: A first transistor, a second transistor, and a capacitor; The gate of the first transistor is electrically connected to the scan line, the source is electrically connected to the data line, and the drain is electrically connected to the first end of the capacitor and the gate of the second transistor; The source of the second transistor is electrically connected to the driving current input terminal and the second end of the capacitor, and the drain of the second transistor is electrically connected to the input terminal of the PWM module.

7. The driving circuit according to claim 5, characterized in that: The control module is further configured to: The total number of grayscales of the display screen is obtained, and the pulse period of the pulse signal is divided according to the total number of grayscales to obtain equal fractions of the pulse period.

8. The driving circuit according to claim 5, characterized in that: The control module is further configured to: Obtaining a current grayscale number of a picture to be displayed, obtaining a grayscale ratio of the current grayscale number to the total number of grayscales, and obtaining a grayscale difference ratio according to the grayscale ratio; The grayscale difference ratio is a difference between 1 and the grayscale ratio.

9. The driving circuit according to claim 5, characterized in that: The control module is further configured to: The grayscale differential ratio is obtained, and the grayscale differential ratio is used as the duty cycle of the pulse signal to control the output of the PWM module.

10. An AMOLED display screen, characterized in that: The driving circuit comprises the driving circuit according to any one of claims 5 to 9, wherein a plurality of the driving circuits constitute an array circuit of an AMOLED display screen to drive each sub-pixel.

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