Method for correcting precise gray scale of electrowetting electronic paper display

Abstract

The application provides a correction method for precise gray scale of an electrowetting electronic paper display. When displaying gray scale, the electrowetting display is provided with brightness L and voltage V, and the hysteresis characteristic curve (L1(V), L2(V)) of the electrowetting display is formed by the advancing contact angle and the receding contact angle of the electronic paper ink, respectively. Under the same driving voltage, the display brightness of the electrowetting electronic paper display depends on the size relationship between the voltage of the previous frame or sub-frame V n and the voltage of the current frame or sub-frame V m The correction method compensates the original driving voltage according to the voltage relationship between the previous frame and the current frame or the previous sub-frame and the current sub-frame of the displayed image, and according to the hysteresis characteristic curve L1(V), L2(V) of the electrowetting display, so as to achieve precise gray scale modulation. The application is used for adjusting the problem that the driving waveform of the gray scale level is not accurate enough due to the influence of the contact angle on the electrowetting hysteresis characteristic, so as to realize precise gray scale modulation.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to a method for correcting the accurate grayscale of an electrowetting electronic paper display. Background Technology

[0002] Electrowetting electronic paper is a novel reflective display technology that combines paper-based displays with electronic displays. On the one hand, electrowetting electronic paper display technology is characterized by its eye-friendly nature, low power consumption, ability to be displayed in sunlight, and lack of the need for a backlight module; on the other hand, it boasts advantages such as high contrast, high brightness, and wide viewing angles. Therefore, electrowetting electronic paper has become an important research direction in emerging display technologies.

[0003] Due to the photoelectric properties and device characteristics of electrowetting, electrowetting electronic paper also faces certain display technology challenges, such as ink backflow and ink cracking. Furthermore, under the combined influence of liquid surface tension and driving voltage, the change in the electrowetting contact angle occurs in three stages, exhibiting a non-linear relationship with voltage changes. These stages can be broadly categorized into a static region, a transition region, and a saturation region. In the static and saturation regions, the electrowetting contact angle shows little change with voltage; however, in the transition region, it changes rapidly with voltage variations. Due to these characteristics, the ink aperture ratio formed under the same driving voltage exhibits inconsistency during the voltage rise and fall phases of the actual driving process; the same aperture ratio can be achieved with different driving voltages. We term this phenomenon as the ink hysteresis characteristic of electrowetting electronic paper, and the corresponding voltage-aperture ratio or brightness curve is called the hysteresis curve. Due to the existence of the hysteresis curve, the actual brightness during the driving process cannot be achieved as desired, which leads to deviations in the grayscale implementation. There may be grayscales driven by different driving waveforms, and their actual display effects are inconsistent, failing to achieve the display effect expected by the driving waveform. Summary of the Invention

[0004] This invention proposes a method for correcting the precise grayscale of an electrowetting electronic paper display, which is used to address the problem of insufficient precision in the driving waveform of grayscale levels caused by the influence of the electrowetting hysteresis characteristics of the contact angle, so as to achieve precise grayscale modulation.

[0005] The present invention adopts the following technical solution.

[0006] A method for correcting the accurate grayscale of an electrowetting electronic paper display, wherein when the electrowetting display displays grayscale, the brightness is set to L and the voltage to V. The hysteresis characteristic curves (L1(V), L2(V)) of the electrowetting display are formed by the advancing contact angle and receding contact angle of the electronic paper ink, respectively. Under the same driving voltage, the display brightness of the electrowetting electronic paper display depends on the previous frame or subframe V.n With this frame or subframe V m The correction method is based on the voltage relationship between the preceding and following frames or subframes of the displayed image. The original driving voltage is compensated according to the hysteresis characteristic curves L1(V) and L2(V) of the electrowetting display to achieve accurate grayscale modulation.

[0007] In the hysteresis characteristic curve of the electrowetting display: under the action of rising voltage, the electro-optic characteristics of the electrowetting display satisfy L1(V); Under the action of a decreasing voltage, the electro-wetting electro-optic characteristics of the electro-wetting display satisfy L2(V). Under the same driving voltage, the display brightness of the electro-wetting electronic paper display depends on the previous frame or sub-frame V. n With this frame or subframe V m Size relationship; Under the same driving voltage, the display brightness of an electrowetting electronic paper display depends on the previous frame or subframe V. n With this frame or subframe V m The size relationship.

[0008] When the modulation mode is frame, the electrowetting display shows the voltage relationship between the preceding and following frames of the reference image, which depends on the brightness. When the modulation mode is subframe, the electrowetting display shows the voltage relationship between the preceding and following subframes within a frame of the reference image, which depends on the brightness.

[0009] The display brightness of the electrowetting electronic paper display is determined by V. n With V m The magnitude of the voltage determines that when V n Greater than V m If the brightness of this frame or subframe satisfies L2(V) m When V n Less than the voltage V of this frame m The display brightness meets L1(V) m This results in inconsistent display brightness and inaccurate grayscale under the same voltage conditions within the same frame.

[0010] The specific compensation method for the original driving voltage is as follows: Based on the photoelectric characteristic curve L(V) referenced in the original driving design of the display, determine the voltage V that needs to be compensated. m The desired brightness L m The size, through V n With V m The magnitude of the voltage determines whether the drive voltage correction is referenced to L1 (V) or L2 (V), thus adjusting the brightness L. m Substituting L1(V) or L2(V) into the equation, we can find the value that satisfies L. m Voltage magnitude V Lm L m=L1(V Lm ) or L m =L2(V Lm ), then V m Compensation to V Lm .

[0011] The via V n With V m The magnitude of the voltage determines whether the drive voltage correction is referenced to L1 (V) or L2 (V). The determination method is based on when V... n Greater than V m Then refer to L2(V); when V n Less than voltage V m Then refer to L1(V).

[0012] In the compensation method, the brightness is used as the independent variable by using the equation corresponding to the photoelectric characteristic curve, and the two corresponding brightness values ​​are obtained by inverse operation.

[0013] The method for measuring and confirming the photoelectric characteristic curve of the electrowetting display is to obtain the correspondence between brightness and voltage through a test platform, fit the measurement data, and obtain the curve equation.

[0014] The photoelectric characteristic curves are the hysteresis curves (L1(V), L2(V)) of the electrowetting electronic paper display, which correspond to the ink hysteresis phenomenon of the electrowetting display. That is, the display brightness of the electrowetting electronic paper display depends on the previous frame or subframe V. n With this frame or subframe V m The size relationship.

[0015] In the photoelectric property curve, L n For a specific brightness level, the intersection of its extension line and the hysteresis curve is the achievable brightness L. n The potential, where V1 is the brightness L achieved in the hysteresis rise curve. n The corresponding potential, V2 is the brightness L achieved in the hysteresis descent curve. n The corresponding potential, that is, satisfying the formula L n =L1(V1)=L2(V2).

[0016] This invention addresses the problem of inaccurate driving waveforms for grayscale levels caused by the nonlinear relationship between contact angle and voltage, thereby achieving precise grayscale modulation. Attached Figure Description

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Appendix Figure 1 This is a schematic diagram of the correction process according to an embodiment of the present invention; Appendix Figure 2This is a schematic diagram of the hysteresis curve in an embodiment of the present invention; Appendix Figure 3 This is a schematic diagram of the photoelectric characteristics of an embodiment of the present invention; Appendix Figure 4 This is a schematic diagram of the 8-grayscale driving waveform design according to an embodiment of the present invention; Appendix Figure 5 This is a schematic diagram comparing the fifth grayscale driving waveform before and after the correction in an embodiment of the present invention. Detailed Implementation

[0018] The basic principles and features of the present invention will be described and explained below with reference to the accompanying drawings. The specific examples given are only applicable to the present invention and are not intended to limit the scope of the present invention.

[0019] Electrowetting electronic paper is a novel display device that relies on applying voltage to the ink to change the surface tension of the droplets, thereby causing the ink to shrink and spread on the substrate, ultimately achieving different grayscale effects. The aperture ratio of electrowetting electronic paper refers to the percentage of the size of the ink droplets in a single pixel to the total pixel size, serving as a criterion for judging the ink shrinkage in an electrowetting electronic paper display. Due to the influence of substrate material, ink chemical composition, and other device materials, the aperture ratio varies at different stages under the same driving voltage, causing the display brightness of an electrowetting electronic paper display to depend on the previous frame or subframe V. n With this frame or subframe V m The magnitude of the relationship between the two. This phenomenon is called ink hysteresis in electrowetting electronic paper, and the photoelectric characteristic curves of this phenomenon are called the hysteresis curves (L1(V), L2(V)) of electrowetting electronic paper display screen. Figure 2 The diagram shows the hysteresis curves of electrowetting electronic paper during actual display, consisting of two curves: a voltage rise curve L1 (V) and a voltage fall curve L2 (V). Figure 2 As shown, when the applied voltage is in the rising phase, that is, when the voltage value of the next frame or subframe is higher than that of the previous frame or subframe, the relationship between brightness and the changing voltage is shown by the curve on the right; when the applied voltage is in the falling phase, that is, when the voltage value of the next frame or subframe is lower than that of the previous frame or subframe, the relationship between brightness and the changing voltage is shown by the curve on the left.

[0020] Where L n For a specific brightness level, the intersection of its extension line and the hysteresis curve is the achievable brightness L. n The potential, where V1 is the brightness L achieved in the hysteresis rise curve. n The corresponding potential, V2 is the brightness L achieved in the hysteresis descent curve. n The corresponding potential, that is, satisfying the formula L n =L1(V1)=L2(V2).

[0021] This example provides a method for correcting the accurate grayscale of an electrowetting electronic paper display. It is used to address the problem that the driving waveform for achieving grayscale levels is not accurate enough due to the nonlinear relationship between the contact angle and voltage, so as to achieve accurate grayscale modulation.

[0022] As shown in the figure, a method for correcting the accurate grayscale of an electrowetting electronic paper display is described. When displaying grayscale, the brightness of the electrowetting display is set to L, and the voltage to V. The hysteresis characteristic curves (L1(V), L2(V)) of the electrowetting display are formed by the forward contact angle and backward contact angle of the electronic paper ink, respectively. Under the same driving voltage, the display brightness of the electrowetting electronic paper display depends on the previous frame or subframe V. n With this frame or subframe V m The correction method is based on the voltage relationship between the preceding and following frames or subframes of the displayed image. The original driving voltage is compensated according to the hysteresis characteristic curves L1(V) and L2(V) of the electrowetting display to achieve accurate grayscale modulation.

[0023] In the hysteresis characteristic curve of the electrowetting display: under the action of rising voltage, the electro-optic characteristics of the electrowetting display satisfy L1(V); Under the action of a decreasing voltage, the electro-wetting electro-optic characteristics of the electro-wetting display satisfy L2(V). Under the same driving voltage, the display brightness of the electro-wetting electronic paper display depends on the previous frame or sub-frame V. n With this frame or subframe V m Size relationship; Under the same driving voltage, the display brightness of an electrowetting electronic paper display depends on the previous frame or subframe V. n With this frame or subframe V m The size relationship.

[0024] When the modulation mode is frame, the electrowetting display shows the voltage relationship between the preceding and following frames of the reference image, which depends on the brightness. When the modulation mode is subframe, the electrowetting display shows the voltage relationship between the preceding and following subframes within a frame of the reference image, which depends on the brightness.

[0025] The display brightness of the electrowetting electronic paper display is determined by V. n With V m The magnitude of the voltage determines that when V n Greater than V m If the brightness of this frame or subframe satisfies L2(V) m When V n Less than the voltage V of this frame m The display brightness meets L1(V) m This results in inconsistent display brightness and inaccurate grayscale under the same voltage conditions within the same frame.

[0026] The specific compensation method for the original driving voltage is as follows: Based on the photoelectric characteristic curve L(V) referenced in the original driving design of the display, determine the voltage V that needs to be compensated. m The desired brightness L m The size, through V n With V m The magnitude of the voltage determines whether the drive voltage correction is referenced to L1 (V) or L2 (V), thus adjusting the brightness L. m Substituting L1(V) or L2(V) into the equation, we can find the value that satisfies L. m Voltage magnitude V Lm L m =L1(V Lm ) or L m =L2(V Lm ), then V m Compensation to V Lm .

[0027] The via V n With V m The magnitude of the voltage determines whether the drive voltage correction is referenced to L1 (V) or L2 (V). The determination method is based on when V... n Greater than V m Then refer to L2(V); when V n Less than voltage V m Then refer to L1(V).

[0028] In the compensation method, the brightness is used as the independent variable by using the equation corresponding to the photoelectric characteristic curve, and the two corresponding brightness values ​​are obtained by inverse operation.

[0029] The method for measuring and confirming the photoelectric characteristic curve of the electrowetting display is to obtain the correspondence between brightness and voltage through a test platform, fit the measurement data, and obtain the curve equation.

[0030] The photoelectric characteristic curves are the hysteresis curves (L1(V), L2(V)) of the electrowetting electronic paper display, which correspond to the ink hysteresis phenomenon of the electrowetting display. That is, the display brightness of the electrowetting electronic paper display depends on the previous frame or subframe V. n With this frame or subframe V m The size relationship.

[0031] In the photoelectric property curve, L n For a specific brightness level, the intersection of its extension line and the hysteresis curve is the achievable brightness L. n The potential, where V1 is the brightness L achieved in the hysteresis rise curve. n The corresponding potential, V2 is the brightness L achieved in the hysteresis descent curve. nThe corresponding potential, that is, satisfying the formula L n =L1(V1)=L2(V2).

[0032] Example: The general processing method for this example includes the following steps: Figure 4 As an embodiment of the present invention, before using the present invention, refer to Figure 3 The photoelectric characteristic curves and grayscale driving waveform design diagram are shown in Figure 8. Figure 3 The horizontal axis represents the driving voltage, and the vertical axis represents the brightness. This waveform has sub-frames; one frame consists of a preset frame and two sub-frames. This waveform is used to drive a single electrowetting pixel. This embodiment takes the 5th gray level in an 8-grayscale correction as an example.

[0033] The display driving modulation method determines the voltage reference relationship between the preceding and following frames. If the current modulation method is a subframe, then the reference is the voltage relationship between the preceding and following subframes in a frame of the image.

[0034] The via V n With V m The magnitude of the voltage determines whether to correct the reference L1(V) or L2(V), and the determination method is as follows: when V n Greater than V m Then refer to L2(V); when V n Less than voltage V m If so, then refer to L1(V). The preset frame is lower than subframe 1 and subframe 1 is higher than subframe 2. Therefore, during the correction process, subframe 1 refers to L1(V) and subframe 2 refers to L2(V).

[0035] The voltage V to be compensated is determined based on the photoelectric characteristic curve L(V). m The desired brightness L m The size of L m Satisfying formula L m =L(V), the potential magnitudes of the two subframes in the waveform are determined according to... Figure 3 Substitute into formula L m =L(V) can be used to obtain the expected brightness L of each subframe without considering hysteresis characteristics. m The specific brightness levels are as follows: 30V corresponds to 68 cd / m². 2 10V corresponds to 38cd / m 2 .

[0036] The via V n With V m The magnitude of the voltage determines whether to correct the reference L1 (V) or L2 (V), thus adjusting the brightness L. m Substitute L1(V) or L2(V) to obtain the voltage magnitude V that satisfies the condition. Lm Lm =L1(V Lm ) or L m =L2(V Lm ), then V m Compensation to V Lm . Figure 2 To correct the reference hysteresis curve, L m =68cd / m 2 Substitute L1(V), L m =38cd / m 2 Substituting L2(V), we obtain the voltage magnitude V corresponding to the reference hysteresis characteristic. m1 =30V, V m2 =4V, which, when combined, forms a drive waveform capable of precise grayscale modulation. Figure 5 This is a comparison of the fifth grayscale driving waveform before and after correction.

Claims

1. A method for correcting the precise grayscale of an electrowetting electronic paper display, characterized in that: When the electrowetting electronic paper display displays grayscale, let the brightness be L and the voltage be V. The hysteresis characteristic curves L1(V) and L2(V) of the electrowetting electronic paper display are formed by the advancing contact angle and receding contact angle of the electronic paper ink, respectively. Under the same driving voltage, the display brightness of the electrowetting electronic paper display depends on the previous frame or subframe V. n With this frame or subframe V m The voltage relationship is corrected by compensating the original driving voltage based on the voltage relationship between the preceding and following frames or subframes of the displayed image, according to the hysteresis characteristic curves L1(V) and L2(V) of the electrowetting electronic paper display, in order to achieve accurate grayscale modulation. The specific compensation method for the original driving voltage is as follows: Based on the photoelectric characteristic curve L(V) referenced in the original driving design of the display, determine the voltage V that needs to be compensated. m The desired brightness L m The size, through V n With V m The magnitude of the voltage determines whether the drive voltage correction is referenced to L1 (V) or L2 (V), thus adjusting the brightness L. m Substituting L1(V) or L2(V) into the equation, we can find the value that satisfies L. m Voltage magnitude V Lm L m =L1(V Lm ) or L m =L2(V Lm ), then V m Compensation to V Lm ; The via V n With V m The magnitude of the voltage determines whether the drive voltage correction is referenced to L1 (V) or L2 (V). The determination method is based on when V... n Greater than V m Then refer to L2(V); when V n Less than voltage V m Then refer to L1(V); In the photoelectric property curve, L n For a specific brightness level, the intersection of its extension line and the hysteresis curve is the achievable brightness L. n The potential, where V1 is the brightness L achieved in the hysteresis rise curve. n The corresponding potential, V2 is the brightness L achieved in the hysteresis descent curve. n The corresponding potential, that is, satisfying the formula L n =L1(V1)=L2(V2).

2. The method for correcting the precise grayscale of an electrowetting electronic paper display according to claim 1, characterized in that: In the hysteresis characteristic curve of the electrowetting electronic paper display: under the action of rising voltage, the electro-optic characteristics of the electrowetting electronic paper display satisfy L1(V). Under the action of a decreasing voltage, the electro-wetting electro-optic characteristics of an electro-wetting electronic paper display satisfy L2(V). Under the same driving voltage, the display brightness of the electro-wetting electronic paper display depends on the previous frame or subframe V. n With this frame or subframe V m Size relationship; Under the same driving voltage, the display brightness of an electrowetting electronic paper display depends on the previous frame or subframe V. n With this frame or subframe V m The size relationship.

3. The method for correcting the precise grayscale of an electrowetting electronic paper display according to claim 2, characterized in that: When the modulation mode is frame, the brightness of the electrowetting electronic paper display depends on the voltage relationship between the preceding and following frames of the reference image. When the modulation mode is subframe, the brightness of the electrowetting electronic paper display depends on the voltage relationship between the preceding and following subframes within a frame of the reference image.

4. The method for correcting the precise grayscale of an electrowetting electronic paper display according to claim 3, characterized in that: The display brightness of the electrowetting electronic paper display is determined by V. n With V m The magnitude of the voltage determines that when V n Greater than V m If the brightness of this frame or subframe satisfies L2(V) m When V n Less than the current frame voltage V m The display brightness meets L1(V) m This results in inconsistent display brightness and inaccurate grayscale under the same voltage conditions within the same frame.

5. The method for correcting the precise grayscale of an electrowetting electronic paper display according to claim 1, characterized in that: In the compensation method, the brightness is used as the independent variable by using the equation corresponding to the photoelectric characteristic curve, and the two corresponding brightness values ​​are obtained by inverse operation.

6. The method for correcting the precise grayscale of an electrowetting electronic paper display according to claim 5, characterized in that: The method for measuring and confirming the photoelectric characteristic curve of the electrowetting electronic paper display is as follows: the relationship between brightness and voltage is obtained through a test platform, and the measurement data is fitted to obtain the curve equation.

7. The method for correcting the precise grayscale of an electrowetting electronic paper display according to claim 5, characterized in that: The photoelectric characteristic curves are the hysteresis curves L1(V) and L2(V) of the electrowetting electronic paper display, which correspond to the ink hysteresis phenomenon of the electrowetting electronic paper display. That is, the display brightness of the electrowetting electronic paper display depends on the previous frame or subframe V. n With this frame or subframe V m The size relationship.

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