Flexible display device driving method

Abstract

The invention discloses a flexible display device driving method, which comprises the following steps of: performing first gray scale display in response to a bending position of a flexible display device, the bending times corresponding to the bending position, the bending angle of each time, the first included angle between the channel direction and the bending direction of the thin film transistor, the average use temperature, the average use humidity and the initial material interface density of the thin film transistor are obtained; obtaining a first aging coefficient of the thin film transistor based on the parameters; obtaining a threshold voltage drift distance of the thin film transistor according to the first aging coefficient; obtaining a first initial driving voltage corresponding to the first gray scale; obtaining a first correction driving voltage according to the first initial driving voltage and the threshold voltage drift amount; and applying a first correction driving voltage to the thin film transistor corresponding to the bent part. According to the flexible display device, threshold voltage drift caused by bending and aging of the thin film transistor is compensated, so that the display quality of the flexible display device is improved.

Description

Technical Field

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

[0002] Flexible display devices are a type of display technology that uses flexible substrates instead of traditional rigid glass substrates. They can be bent, folded, or even curled, and are considered an important development direction for future display technology. Flexible display devices are reshaping the way humans and machines interact by subverting traditional forms. Despite technical challenges such as cost and lifespan, with advances in material science and technology, their application scenarios will continue to expand, and they are expected to play a greater role in wearable devices, the Internet of Things, the metaverse, and other fields in the future. In the short term, foldable phones will remain a market hotspot. In the long run, curled and stretchable screens may become the next generation of mainstream forms.

[0003] At present, flexible display screens are flexible because they can be bent to meet user needs. However, bending also brings problems. As the number of times the display screen is bent increases, the flexible TFT (thin film transistor) in the display is prone to damage and aging after repeated bending or stretching, which in turn causes the threshold voltage (Vth) to drift, resulting in drive current deviation and uneven brightness. How to solve the threshold voltage drift caused by bending and aging has become a difficult problem in improving the display quality of flexible display screens. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a flexible display device driving method, aiming to compensate for the threshold voltage drift caused by bending and aging of the thin film transistor by improving the driving method, so as to improve the display quality of the flexible display device.

[0005] To achieve the above object, the present invention provides a flexible display device driving method, the method comprising:

[0006] Step S1, in response to the bending part of the flexible display device needing to perform a first grayscale display, obtaining the number of bends corresponding to the bending part, the bending angle of each time, the first angle between the channel direction of the thin film transistor and the bending direction, the average use temperature, the average use humidity, and the initial material interface density of the thin film transistor; wherein the bending part is provided with an angle sensor, a temperature sensor, and a humidity sensor;

[0007] Step S2, obtaining a bending fatigue damage coefficient of the thin film transistor corresponding to the bending position according to the number of bending times and the bending angle of each bending; obtaining the interface defect accumulation value according to the number of bending times, the bending angle of each bending, the bending fatigue damage coefficient and the initial material interface density;

[0008] Step S3, obtaining a first aging coefficient of the thin film transistor according to the number of bends, the bending angle of each bend, the first angle, the average use temperature, the average use humidity and the cumulative value of interface defects;

[0009] Step S4, obtaining a threshold voltage drift of the thin film transistor according to the first aging coefficient; wherein the threshold voltage drift increases as the first aging coefficient increases;

[0010] Step S5, obtaining a first initial driving voltage corresponding to the first grayscale display; obtaining a first corrected driving voltage according to the first initial driving voltage and the threshold voltage drift; and applying the first corrected driving voltage to the thin film transistor corresponding to the bending portion.

[0011] Optionally, step S3 includes:

[0012] according to

[0013]

[0014] Obtain the first aging coefficient η; wherein η 0 is the reference aging coefficient, A is the directional sensitivity coefficient, θ is the first angle, N is the number of bends, α i is the bending angle at each time, T is the average operating temperature, E a is the activation energy, k is the Boltzmann constant, W is the average humidity, n is the humidity sensitivity index, D M is the cumulative value of the interface defects; the directional sensitivity coefficient and the humidity sensitivity index are related to the material of the thin film transistor and are obtained in advance through the material correspondence relationship.

[0015] Optionally, in step S2, obtaining the interface defect accumulation value according to the number of bends, the bending angle of each bend, the bending fatigue damage coefficient and the initial material interface density includes:

[0016] according to

[0017]

[0018] Obtain the interface defect accumulation value D M ; Among them, D M is the cumulative value of the interface defects, γ is the defect sensitivity coefficient, D it0 is the initial material interface density, k is the bending fatigue damage coefficient, N is the number of bends, α i is the bending angle each time; the defect sensitivity coefficient is related to the material of the thin film transistor and is obtained in advance through the material correspondence relationship.

[0019] Optionally, in step S4, the threshold voltage drift is proportional to the first aging coefficient, and the proportionality coefficient is obtained in advance through experiments.

[0020] Optionally, the first angle has a value range of 0-90°.

[0021] Optionally, after step S4, the method further includes:

[0022] When the threshold voltage drift is greater than the maximum threshold voltage drift, it is determined that the corresponding thin film transistor cannot perform driving voltage correction, and an alarm is issued.

[0023] Optionally, in step S1, the method further includes:

[0024] The temperature sensor is controlled to collect a first temperature at the bending portion according to a first preset period; a total usage time of the flexible display device is obtained; and an average usage temperature is obtained according to the first preset period, the first temperature and the total usage time.

[0025] Optionally, in step S1, the method further includes:

[0026] The humidity sensor is controlled to collect the first humidity at the bending part according to a second preset period; the total usage time of the flexible display device is obtained; and the average usage humidity is obtained according to the second preset period, the first humidity and the total usage time.

[0027] Optionally, the angle sensor is used to collect the number of bends and the angle of each bend at the bend of the flexible display device.

[0028] Beneficial effects of the present invention: 1. The present invention obtains the first aging coefficient of the thin film transistor according to the number of bends, each bend angle, the first angle, the average use temperature, the average use humidity and the cumulative value of interface defects; according to the first aging coefficient, the threshold voltage drift of the thin film transistor is obtained; the first initial driving voltage corresponding to the first grayscale display is obtained; according to the first initial driving voltage and the threshold voltage drift, the first corrected driving voltage is obtained. The present invention comprehensively considers the influence of various factors on the aging of the thin film transistor, and then obtains the first aging coefficient for evaluating the aging degree of the thin film transistor, obtains the threshold voltage drift corresponding to the first aging coefficient, and then changes the driving voltage to make corresponding compensation, so that the luminous brightness corresponding to the new corrected driving voltage matches the first grayscale. Compared with only considering the influence of the number of bends on the threshold voltage drift, the present invention comprehensively considers various influencing factors, so the corresponding driving compensation of the present invention will be more accurate, the display effect will be more uniform, and the display quality will be higher. 2. When considering the influence of bending on the aging degree of the thin film transistor, the present invention not only considers the number of bends, but also considers the angle of each bend. In this way, the influence of each bend on the aging degree can be effectively distinguished, and accurate driving compensation can be achieved to avoid the problem of compensation fuzziness.

[0029] In summary, the present invention can compensate for the threshold voltage drift caused by aging of the thin film transistor by improving the driving method, so as to improve the display quality of the flexible display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of a method for driving a flexible display device provided by a specific embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention discloses a method for driving a flexible display device. Those skilled in the art can refer to the content of this article and appropriately improve the technical details. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments. It is obvious that relevant personnel can modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0032] The applicant has found that: At present, flexible display screens are flexible because they can be bent to meet user needs. However, bending also brings problems. As the number of times the display screen is bent increases, the flexible TFT (thin film transistor) in the display is prone to damage and aging after repeated bending or stretching, which causes the threshold voltage (Vth) to drift, resulting in driving current deviation and uneven brightness. The main factors of flexible TFT aging damage include: the number of bends, the angle of each bend, the angle between the TFT channel direction and the bending direction, temperature and humidity coupling, and interface defects caused by bending. How to compensate the bending area based on these factors to make the brightness uniform has become a problem.

[0033] Therefore, an embodiment of the present invention provides a method for driving a flexible display device, such as Figure 1 As shown, the method includes:

[0034] Step S1, in response to the need to perform a first grayscale display at a bend of the flexible display device, obtain the number of bends corresponding to the bend, the angle of each bend, the first angle between the channel direction of the thin film transistor and the bend direction, the average operating temperature, the average operating humidity, and the initial material interface density of the thin film transistor.

[0035] Among them, an angle sensor, a temperature sensor and a humidity sensor are arranged at the bending part.

[0036] The number of bends and the bend angle will directly introduce micro-strain into the thin film transistor at the bend. Repeated loading will cause the thin film transistor to degrade. When there is an angle between the TFT channel direction (carrier transmission direction) and the bending direction, the channel material is subjected to different strain types (stretching / compression) and sizes, that is, different micro-strains. Therefore, the first angle is also an important factor affecting aging. High temperature accelerates the migration of ions in the gate oxide layer below (such as Na + , K + The aging rate of thin film transistors increases with temperature due to the increase of contamination) and crystallization or oxidation of organic semiconductors. In a high humidity environment, water molecules penetrate into the interface, causing corrosion of metal electrodes (such as Al and Cu). The oxygen vacancies of oxide semiconductors (such as IZO) increase, and thin film transistors age. The cumulative value of interface defects increases with the increase of bending times and bending angles. Edge defects tend to increase during bending, resulting in increased discreteness of threshold voltage, so it is also used as a factor to evaluate aging.

[0037] In this specific embodiment, the value range of the first angle is 0-90°. The angle between the TFT channel direction and the bending direction is based on the minimum angle.

[0038] In this specific embodiment, in step S1, the method further includes:

[0039] The temperature sensor is controlled to collect a first temperature at the bending part according to a first preset period; the total use time of the flexible display device is obtained; and the average use temperature is obtained according to the first preset period, the first temperature and the total use time.

[0040] In this specific embodiment, in step S1, the method further includes:

[0041] The humidity sensor is controlled to collect the first humidity at the bending part according to the second preset period; the total use time of the flexible display device is obtained; and the average use humidity is obtained according to the second preset period, the first humidity and the total use time.

[0042] It should be noted that the use of average operating temperature and average operating humidity can comprehensively reflect the effects of temperature and humidity on thin film transistors.

[0043] In this specific embodiment, the angle sensor is used to collect the number of bends and the angle of each bend at the bend of the flexible display device.

[0044] Step S2, obtaining the bending fatigue damage coefficient of the thin film transistor corresponding to the bending point according to the number of bending times and the bending angle of each time; obtaining the interface defect accumulation value according to the number of bending times, the bending angle of each time, the bending fatigue damage coefficient and the initial material interface density.

[0045] It should be noted that the bending fatigue damage coefficient is positively correlated with the number of bending times and the bending angle of each time.

[0046] In this specific embodiment, in step S2, the interface defect accumulation value is obtained according to the number of bends, the bending angle of each bend, the bending fatigue damage coefficient and the initial material interface density, including:

[0047] according to

[0048]

[0049] Obtain the interface defect accumulation value D M ; Among them, D M is the cumulative value of interface defects, γ is the defect sensitivity coefficient, D it0 is the initial material interface density, k is the bending fatigue damage coefficient, N is the number of bends, α i is the bending angle for each time; the defect sensitivity coefficient is related to the material of the thin film transistor and is obtained in advance through the material correspondence relationship.

[0050] It is worth mentioning that since the defect sensitivity coefficients of different materials are different and are relatively stable under normal environmental conditions, the defect sensitivity coefficient can also be regarded as a material property.

[0051] Step S3, obtaining a first aging coefficient of the thin film transistor according to the bending times, each bending angle, the first angle, the average use temperature, the average use humidity and the cumulative value of interface defects.

[0052] In this specific embodiment, step S3 includes:

[0053] according to

[0054]

[0055] Obtain the first aging coefficient η; wherein η 0 is the reference aging coefficient, A is the directional sensitivity coefficient, θ is the first angle, N is the number of bends, α i is the bending angle at each time, T is the average operating temperature, E a is the activation energy, k is the Boltzmann constant, W is the average humidity, n is the humidity sensitivity index, D M is the cumulative value of interface defects; the directional sensitivity coefficient and humidity sensitivity index are related to the material of the thin film transistor and are obtained in advance through the material correspondence relationship.

[0056] It should be noted that, by summarizing the influence of various factors on the aging of the thin film transistor, the above formula can be obtained to characterize the aging degree of the thin film transistor.

[0057] It is worth mentioning that the directional sensitivity coefficient and humidity sensitivity index vary with different materials, and their values ​​are relatively stable under normal environmental conditions. Therefore, the directional sensitivity coefficient and humidity sensitivity index can be regarded as material properties.

[0058] Step S4: obtaining a threshold voltage drift of the thin film transistor according to the first aging coefficient.

[0059] The threshold voltage drift increases with the increase of the first aging coefficient.

[0060] In this specific embodiment, in step S4, the threshold voltage drift is proportional to the first aging coefficient, and the proportionality coefficient is obtained in advance through experiments.

[0061] It should be noted that the more severe the aging of the thin film transistor is, the greater the threshold voltage drift is. Under the same driving voltage, the greater the display grayscale deviation is, the worse the display effect is.

[0062] In this specific embodiment, after step S4, the method further includes:

[0063] When the threshold voltage drift is greater than the maximum threshold voltage drift, it is determined that the corresponding thin film transistor cannot perform drive voltage correction, and an alarm is issued.

[0064] It should be noted that when the threshold voltage drift is too large, the grayscale deviation cannot be corrected even with the maximum compensation driving voltage, and timely reminders should be made at this time.

[0065] Step S5, obtaining a first initial driving voltage corresponding to the first gray scale; obtaining a first corrected driving voltage according to the first initial driving voltage and the threshold voltage drift; and applying the first corrected driving voltage to the thin film transistor corresponding to the bending part.

[0066] The embodiment of the present invention obtains the first aging coefficient of the thin film transistor according to the number of bends, each bending angle, the first angle, the average operating temperature, the average operating humidity and the cumulative value of interface defects; obtains the threshold voltage drift of the thin film transistor according to the first aging coefficient; obtains the first initial driving voltage corresponding to the first grayscale display; obtains the first corrected driving voltage according to the first initial driving voltage and the threshold voltage drift. The embodiment of the present invention comprehensively considers the influence of various factors on the aging of the thin film transistor, and then obtains the first aging coefficient for evaluating the aging degree of the thin film transistor, obtains the threshold voltage drift corresponding to the first aging coefficient, and then performs corresponding compensation by changing the driving voltage, so that the luminous brightness corresponding to the new corrected driving voltage matches the first grayscale. Compared with only considering the influence of the number of bends on the threshold voltage drift, the embodiment of the present invention comprehensively considers various influencing factors, so the corresponding driving compensation of the embodiment of the present invention will also be more accurate, the display effect will be more uniform, and the display quality will be higher.

[0067] When considering the influence of bending on the aging degree of the thin film transistor, the embodiment of the present invention not only considers the number of bends, but also considers the angle of each bend. In this way, the influence of each bend on the aging degree can be effectively distinguished, thereby achieving accurate drive compensation and avoiding the problem of compensation fuzziness.

[0068] In summary, the embodiments of the present invention can compensate for the threshold voltage drift caused by aging of the thin film transistor by improving the driving method, so as to improve the display quality of the flexible display device.

[0069] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0070] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0071] The above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for driving a flexible display device, characterized in that: The method comprises: Step S1, in response to the need to perform a first grayscale display at a bend of the flexible display device, obtaining the number of bends corresponding to the bend, the angle of each bend, the first angle between the channel direction of the thin film transistor and the bend direction, the average use temperature, the average use humidity, and the initial material interface density of the thin film transistor; wherein the bend is provided with an angle sensor, a temperature sensor, and a humidity sensor; Step S2, obtaining a bending fatigue damage coefficient of the thin film transistor corresponding to the bending position according to the number of bending times and the bending angle of each bending; obtaining the interface defect accumulation value according to the number of bending times, the bending angle of each bending, the bending fatigue damage coefficient and the initial material interface density; Step S3, obtaining a first aging coefficient of the thin film transistor according to the number of bends, the bending angle of each bend, the first angle, the average use temperature, the average use humidity and the cumulative value of interface defects; Step S4, obtaining a threshold voltage drift of the thin film transistor according to the first aging coefficient; wherein the threshold voltage drift increases as the first aging coefficient increases; Step S5, obtaining a first initial driving voltage corresponding to the first gray scale; obtaining a first corrected driving voltage according to the first initial driving voltage and the threshold voltage drift; and applying the first corrected driving voltage to the thin film transistor corresponding to the bending part.

2. The flexible display device driving method according to claim 1, characterized in that: The step S3 comprises: according to Obtain the first aging coefficient η; wherein η0 is the reference aging coefficient, A is the directional sensitivity coefficient, θ is the first angle, N is the number of bends, α i is the bending angle at each time, T is the average operating temperature, E a is the activation energy, k is the Boltzmann constant, W is the average humidity, n is the humidity sensitivity index, D M is the cumulative value of the interface defects; the directional sensitivity coefficient and the humidity sensitivity index are related to the material of the thin film transistor and are obtained in advance through the material correspondence relationship.

3. The flexible display device driving method according to claim 1, characterized in that: The step S2 obtains the interface defect accumulation value according to the bending times, the bending angle of each time, the bending fatigue damage coefficient and the initial material interface density, including: according to Obtain the interface defect accumulation value D M ; Among them, D M is the cumulative value of the interface defects, γ is the defect sensitivity coefficient, D it0 is the initial material interface density, k is the bending fatigue damage coefficient, N is the number of bends, α i is the bending angle each time; the defect sensitivity coefficient is related to the material of the thin film transistor and is obtained in advance through the material correspondence relationship.

4. The flexible display device driving method according to claim 1, characterized in that: In the step S4, the threshold voltage drift is proportional to the first aging coefficient, and the proportionality coefficient is obtained in advance through experiments.

5. The flexible display device driving method according to claim 1, characterized in that: The value range of the first angle is 0-90°.

6. The method for driving a flexible display device according to claim 1, characterized in that: After step S4, the method further includes: When the threshold voltage drift is greater than the maximum threshold voltage drift, it is determined that the corresponding thin film transistor cannot perform driving voltage correction, and an alarm is issued.

7. The flexible display device driving method according to claim 1, characterized in that: In step S1, the method further includes: The temperature sensor is controlled to collect a first temperature at the bending portion according to a first preset period; a total usage time of the flexible display device is obtained; and an average usage temperature is obtained according to the first preset period, the first temperature and the total usage time.

8. The method for driving a flexible display device according to claim 1, wherein: In step S1, the method further includes: The humidity sensor is controlled to collect the first humidity at the bending part according to a second preset period; the total usage time of the flexible display device is obtained; and the average usage humidity is obtained according to the second preset period, the first humidity and the total usage time.

9. The flexible display device driving method according to claim 1, characterized in that: The angle sensor is used to collect the bending times and each bending angle of the bending portion of the flexible display device.

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