TWI882511B - Color electrophoretic display and display method of the same - Google Patents

Abstract

A color electrophoretic display and a display method are provided. The color electrophoretic display includes an achromatic color particle and multiple chromatic color particles. The display method of the color electrophoretic display includes turning on a stylus mode, providing an assigning stylus color, inspecting a movement of the stylus to output a black trace, and transferring the black trace into a color trace having the stylus color when the stylus movement stops. The black trace is shown when the achromatic color particle and the chromatic color particles move towards a top electrode, and a refresh rate of the color of the black trace is smaller than 50 ms. The color of the assigning stylus color and the color of the black trace have brightness difference and at least one of the hue difference and the saturation difference.

Description

Color electrophoresis display and display method thereof

The present disclosure relates to a color electrophoresis display and a display method thereof.

Electrophoretic displays change color by changing the position of charged colored particles relative to the viewing surface and are often called electronic paper. Electrophoretic displays have been widely used in electronic readers or billboards.

Recently, color electrophoresis displays are available in a variety of colors on the market. The application of electrophoresis displays has also been extended to color notes (E-notes) with writing functions. However, color electrophoresis displays require precise control of the position of each color particle. When the electrophoresis medium contains multiple particles, the time required to adjust the particle position is much longer than the time required for black and white displays. Since color electrophoresis displays have more and more complex internal particles (compared to single-color electrophoresis displays), the factors affecting particle movement are more complex, such as electric field switching time, inter-particle gravity, mutual attraction/repulsion of particles when moving, or collisions on the moving path, etc., which makes the color electrophoresis display take a long time to switch colors, for example, the update rate is as high as 500 milliseconds, that is, the color electrophoresis display needs at least 500 milliseconds to present the next display screen when switching colors. Therefore, the update rate of the colored pen writing track is low and the user experience is not good.

Previous technologies such as TWI400674B use a handwriting prediction method to pre-draw possible handwriting to reduce the delay of writing. However, the handwriting prediction method must promptly correct the handwriting prediction errors. For a system where multiple color particles move and mix colors, the movement of particles is not easy. Therefore, when the handwriting prediction is wrong, the particles need more time to move and arrange again. Therefore, the method of TWI400674B is not applicable to the electrophoresis display system of multiple color particles.

In view of this, how to provide a color electrophoretic display that can allow users to have a poor experience due to delayed pen touch updates is still one of the goals that the industry urgently needs to work hard to develop.

A technical aspect of the present disclosure is a display method of a color electrophoresis display, wherein the color electrophoresis display includes a non-color particle and a plurality of color particles.

In one embodiment, a display method of a color electrophoretic display includes turning on a pen writing mode; providing a designated pen writing color; sensing the movement of the stylus to output a black pen writing track, wherein the color of the black pen writing track is presented by non-color particles and color particles near the top electrode, and the color update time of the black pen writing track is less than 50 milliseconds; and sensing the stopping of the stylus to convert the black pen writing track into a color pen writing track having a designated pen writing color, wherein the designated pen writing color and the color of the black pen writing track have a change in brightness and a change in at least one of hue and chroma.

In one embodiment, the color of the black pen writing track is the color with the shortest update time in the color electrophoretic display.

In one embodiment, the update time of the designated pen writing color is 5 to 10 times the update time of the color of the black pen writing track.

In one embodiment, the non-color particles are white, and the color particles are cyan, yellow, and magenta.

In one embodiment, the distance between the black pen writing track and the tip of the stylus is less than 3 mm.

In one embodiment, the display method of the color electrophoretic display further includes determining whether the color difference between the specified pen writing color and the color of the black pen writing trace is greater than 13; if so, selecting a color group whose color difference with the specified pen writing color is less than 13, and then selecting the color with the shortest update time from the group, and presenting the pen writing trace with this color.

In one embodiment, the display method of the color electrophoretic display further includes sensing that the stylus touches the color electrophoretic display and starts to move by using the pressure between the stylus and the color electrophoretic display to change from low to high.

In one embodiment, the method further includes utilizing the pressure between the stylus pen and the color electrophoretic display to change from high to low to sense the stylus pen moving away and stop.

In one embodiment, the step of specifying the pen writing color is before or after the step of sensing the stylus contact.

Another technical aspect of the present disclosure is a color electrophoresis display. The color electrophoresis display includes non-color particles and a plurality of color particles. The non-color particles and the color particles are close to the top electrode to present the pen track formed by the movement of the stylus. The distance between the end point of the pen track and the tip of the stylus is less than 3mm. The color electrophoresis display does not include a color filter.

In the above-mentioned embodiment, the display method of the color electrophoretic display is to first display the black pen track, and the user will not feel the delay of the pen track. After displaying the pen track, the color display step is performed. In the state where the black pen track already exists, the time delay of displaying the color can be less obvious, so it can have the effect of improving the user experience. Therefore, the display method of the color electrophoretic display disclosed in the present invention can reduce the delay of the pen track and provide the effect of color handwriting at the same time.

The following will disclose multiple embodiments of the present invention with drawings. For the purpose of clarity, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present invention. That is to say, in some embodiments of the present invention, these practical details are not necessary. In addition, in order to simplify the drawings, some commonly used structures and components will be depicted in the drawings in a simple schematic manner. And for the sake of clarity, the thickness of the layers and regions in the drawings may be exaggerated, and the same element symbols represent the same elements in the description of the drawings.

The term "bistable" or the like herein refers to a display having first and second display states that are different in at least one optical property, and can change between the first and second display states after receiving a driving source, and is stable in the first and second display states. In addition, some displays are also stable in the intermediate state between the first and second display states, and such displays may be referred to as "multi-stable", but for ease of understanding, the term "multi-stable" or the like herein may cover multi-stable displays.

Some embodiments of the present invention are directed to electro-optical displays, particularly dual-stable electro-optical displays, such as an electrophoretic display based on particle reflection of light, wherein one or more types of colored (black, white or colored)/charged particles are present in a fluid (hereinafter referred to as an electrophoretic medium) and move in the fluid under the influence of an electric field or/and a magnetic field to change the display appearance (or display screen) of the display. The color electrophoretic display of some embodiments of the present invention has a material (i.e., colored/charged particles) that can produce a first and a second display state, and by applying an electric field or/and a magnetic field to the material, the appearance of the material is changed from the first display state to the second display state, and at least one optical property (such as hue, lightness and chroma) of the first and second display states is different.

FIG. 1 is a cross-sectional view of a color electrophoretic display 100 according to an embodiment of the present disclosure. The color electrophoretic display 100 includes a substrate 110, a bottom electrode 120, a top electrode 130, and an electrophoretic medium 140. The thin film transistors (TFTs) on the substrate 110 form an active array of pixels, and the bottom electrodes 120 arranged in rows and columns serve as pixel electrodes. The intersections of the pixel electrodes may correspond to the pixels displayed by the color electrophoretic display 100, thereby forming a matrix image display. An adhesive layer 150 may be provided between the bottom electrode 120 and the electrophoretic medium 140, and an adhesive layer 160 may be provided between the top electrode 130 and the electrophoretic medium 140. The top electrode 130 also has a protective layer 170 for protecting the top electrode 130 .

The bottom electrode 120 and the top electrode 130 may be transparent conductors, such as indium tin oxide (ITO) or indium zinc oxide (IZO), which may be deposited on a transparent substrate, such as polyethylene terephthalate (PET) or polyimide (PI) and then patterned to form electrodes. In addition, the bottom electrode 120 and the top electrode 130 may be made of flexible conductive materials, such as nanometal wires (such as nanosilver wires), conductive polymers, or polymers with conductive additives.

The electrophoretic medium 140 of the color electrophoretic display 100 of some embodiments of the present invention includes four different types of particles, each having a different particle size, color, charge (positive, negative or charged) and/or electron mobility, but not limited to this. In this embodiment, white particles 142, cyan particles 144, yellow particles 146 and magenta particles 148 are taken as examples. The white particles 142 are achromatic particles and are reflective particles. The cyan particles 144, yellow particles 146 and magenta particles 148 are colored particles and are color-reducing particles. The electrophoretic medium 140 is loaded into a micro capsule or a micro cup and formed on the substrate 110 by coating, laminating or spraying. In this embodiment, more than tens of thousands of different colors can be displayed by the above-mentioned 4-particle ink system, and each pixel of the color electrophoretic display 100 can present colors in the full color gamut.

FIG. 2 is a cross-sectional view of a color electrophoretic display 100a according to an embodiment of the present disclosure. The electrophoretic medium 140 is dispersed in microcells or cavities, and the cavities are separated by materials such as dielectrics or polymers. The bottom electrode 120 has segmented areas corresponding to the microcells for driving the particles in each microcell individually. The color electrophoretic display in the present disclosure is not limited to the above-mentioned aspects, and may be, for example, an electrophoretic display having an electrophoretic medium 140 that is a combination of achromatic particles and colored particles, such as an electrophoretic display containing black particles, red particles, green particles, and blue particles; another example is an electrophoretic display containing black particles, red particles, yellow particles, and blue particles; another example is an electrophoretic display containing black particles, white particles, red particles, and yellow particles.

In the field of color, "achromatic" refers to black, white, and various shades of gray. The transition from white to black only has a change in lightness (quantified by brightness), but no changes in hue (quantified by wavelength) and chroma (quantified by saturation). In CIELAB, L* represents lightness, L*=0 is pure black, with a reflectivity or transmittance of 0%; L*=50 represents middle gray; and L*=100 represents white, which means 100% reflectivity and clarity. In this article, a monochrome electrophoretic display refers to an electrophoretic display with "achromatic" particles: white particles or black particles. The display screen only has a change in lightness (i.e., ΔL*) when it transitions from white to black, but no changes in hue and chroma. Specifically, in an electrophoretic display of black and white particles, the driving method of the black and white particles is relatively simple. It only requires two voltages of different polarities (positively charged or negatively charged) to bring the black particles and white particles with opposite charges to the viewing surface respectively. During the movement of the black and white particles, a gray color will naturally appear. For example, in a black screen originally displayed on a white background, when the display color is to be switched (black to white), the black particles move from the display surface electrode (i.e., the top electrode 130) to the driving surface electrode (i.e., the bottom electrode 120), while the white particles move in the opposite direction. Therefore, when the two particles move relative to each other and mix in the electrophoretic medium 140, a gray tone will naturally appear. In summary, in a black and white particle system, it is a natural phenomenon for the monitor to display gray, rather than the display system performing any special calculations or processing.

Compared with achromatic white or black particles, the "chromatic" particles referred to in this article refer to colored particles, such as the color presented by colored particles reflecting light sources. The color changes presented are not just changes in brightness, but also involve changes in hue, lightness and chroma. According to CIELAB, in addition to L*, a* and b* may also be different to produce color differences (that is, ΔE, which can be simply called color difference). For example, when the red color presented by a single magenta particle changes to a color mixed by yellow particles and cyan particles, there are changes in hue, brightness and chroma in the color domain. In order to achieve the above changes in hue, brightness and chroma, a complex driving method must be used to control the movement and mixing of multiple colored particles so that the colored particles are positioned at the required position to display the correct color/image/pattern, etc. In other words, the color electrophoretic display 100a to be processed by the present invention far exceeds the black and white color display type electrophoretic display in terms of the matching of electrophoretic particles and the control of color.

For electrophoretic displays with multi-color particles, the method of driving the particles is complex. A color electrophoretic display with four-color particles can present thousands of colors by precisely controlling the relative position of each particle. One method is to provide a square wave pulse through the driving circuit on the substrate 110, and provide multiple sets of different voltage values to arrange different particles in different ways, so that the final color to be displayed is presented on the viewing surface. However, when there are multiple non-color particles and color particles at the same time, even if a black or white image is to be presented, the response time is not as fast as that of a simple black and white electrophoretic display. One of the purposes of the present invention is to solve the delay in displaying the image of the color electrophoretic display 100a, especially when the color electrophoretic display 100a is used for writing, to provide a user-friendly display mode to minimize the user's perception of pen touch delay.

FIG. 3A to FIG. 3D are schematic diagrams showing the positions of different particles when a color electrophoresis display according to an embodiment of the present disclosure displays different colors. The top of the diagram is the viewing surface and the direction of light incidence. Here, the electrophoresis medium 140 of the color electrophoresis display 100a of FIG. 2 is taken as an example. In FIG. 3A , the white particles 142 reflect light, and the cyan particles 144, the yellow particles 146, and the magenta particles 148 are controlled by the electric field and are located below the white particles 142. The white particles 142 can reflect light from a light source (such as an ambient light source or a front light source of the color electrophoretic display 100a), so that the viewing surface (i.e., above the top electrode 130 (taking the direction presented in the figure in this article as an example)) displays white; in other words, the single color (i.e., white) displayed at this time can indicate that the electric field between the bottom electrode 120 and the top electrode 130 is driven to the extreme state, so that the white particles 142 are close to (or concentrated on) the top electrode 130, while the other particles are far away from (or not close to) the top electrode 130, and present a single color. In FIG. 3B , yellow particles 146 are located above white particles 142 , and light passes through yellow particles 146 and is reflected by white particles 142 , making the viewing surface appear yellow. Similarly, a color electrophoretic display can also display cyan, magenta, red (FIG. 3C ), and blue. In FIG. 3D , all three colored particles are located above white particles 142 , appearing black. In this embodiment, since black is formed by mixing four particles, namely white particles 142, cyan particles 144, yellow particles 146, and magenta particles 148, an extreme driving method can be adopted, such as providing a maximum voltage difference so that the above particles move to the top electrode 130 at the fastest speed under the drive of the high voltage difference for light mixing. Since the moving directions of the four particles are substantially the same, the movement resistance mentioned above is minimized, and black can be displayed with a minimum response time, such as less than 50 milliseconds.

In another embodiment, the particles of the color electrophoretic display may include non-color black particles and colored red particles, blue particles, and green particles. Black particles absorb light, and when red particles, blue particles, and green particles are disposed below black particles, the viewing surface may appear black. When red particles are located above black particles, the viewing surface may appear red. Similarly, when blue particles are located above black particles, the viewing surface may appear red. When green particles are located above black particles, the viewing surface may appear green. When two colored particles are located above black particles, the viewing surface may appear purple, orange, or yellow after mixing. When all three colored particles are located above black particles, the display appears white.

The colors shown in Figures 3A to 3D above can be achieved in a variety of ways. For example, one way is to use the difference in electrophoretic mobility to allow charged particles to move in a specific electric field. During the movement, the distribution of the particles changes, thereby changing the originally provided electric field. Therefore, by adjusting the electric field in multiple stages, the particles required to present the target color can be located close to the viewing surface.

In another embodiment, the intensity of aggregation between particles can be adjusted by surface treatment of the particles. This can be achieved by forming polymers of different thicknesses on the surface of the particles. For example, in this embodiment, it is assumed that the white particles 142 are negatively charged, the cyan particles 144 are positively charged, the yellow particles 146 are negatively charged, and the magenta particles 148 are positively charged. In other embodiments, when the charges carried by the particles are different, the applied voltage and the pulse square wave can be adjusted accordingly. The white particles 142 and the cyan particles 144 have thicker shells. Under this condition, the force between the yellow particles 146 and the magenta particles 148 is the largest, and a higher electric field is required to separate them. The force between the white particles 142 and the cyan particles 144 is second, and is similar to the force between the cyan particles 144 and or the yellow particles 146. The interaction between the white particles 142 and the cyan particles 144 is weaker, but greater than the interaction between particles of the same charge. Based on the above characteristics, under different electric field sizes, specific particles can be aggregated and moved slowly, and specific charges can be moved to a specified position.

In one embodiment, the driving of the colors in FIG. 3A to FIG. 3D can be achieved through five voltages, including two sets of positive voltages, zero voltage, and two sets of negative voltages. For example, 30 volts, 20 volts, 0 volts, -20 volts, and -30 volts can be used, but the present disclosure is not limited thereto. In other embodiments, more sets of positive voltages and negative voltages can be used to form the required pulse waveform to achieve the effect of driving particles.

When white is to be displayed, a square wave oscillating between 0 volts and -20 volts may be applied to move the white particles 142 closer to the viewing surface. When black is to be displayed, a square wave oscillating between 0 volts and +20 volts may be applied to move the three colored particles above the white particles 142. When color is to be displayed, the square wave may oscillate between different voltage values, such as between +30 volts and -20 volts or between -30 volts and +20 volts. In addition, the duration and frequency of the different voltage values are also adjusted according to the color to be presented.

From the perspective of market trends, color electrophoresis displays are the direction of product development. However, as mentioned above, color electrophoresis displays have more internal particles (compared to single-color electrophoresis displays) and the factors affecting particle movement are complex (such as electric field switching, inter-particle attraction, obstacles during particle movement, etc.), which makes the color switching time of color electrophoresis displays longer, resulting in a delay in the display screen. Furthermore, the integration of display and pen writing (or other types of input) is also a function required by users, and the introduction of handwriting function further highlights the disadvantage of color electrophoresis displays in screen delay. Based on the aforementioned embodiment, the response time required to display black (monochrome) is shorter (i.e., the update time/update rate is fast, or the delay time is short), which can be less than 50 milliseconds, and preferably less than 30 milliseconds; while the response time required to display color (especially colors that require more than two particles to mix) is longer, for example 500 milliseconds.

That is to say, color electrophoretic displays usually have the problem of pen trace delay. There is an obvious time lag, or latency, between the input in motion and the display portion of the color electrophoretic display corresponding to the motion. Therefore, pen writing requires a short update time so that the user can view the written handwriting instantly and without delay. According to research, the time difference that the human eye can recognize is approximately between 55 and 65 milliseconds, so the delay time is as short as possible, less than 100 milliseconds, less than 65 milliseconds, less than 42 milliseconds, less than 30 milliseconds, and less than 20 milliseconds. The display method of the color electrophoretic display disclosed in the present disclosure will be described below to provide a method for reducing the pen trace delay while providing the effect of color handwriting. The aforementioned color electrophoretic displays 100, 100a and various methods of displaying colors can all be used.

Figure 4 is a display method of a color electrophoretic display according to an embodiment of the present disclosure. In step S1, the pen writing mode is turned on. For example, in this embodiment, the pen writing mode of the color electrophoretic display can be achieved by combining a capacitive touch sensor with a pressure sensor. The signal from the finger and the signal from the stylus have different polarities, while non-artificial signals such as ghost points and other noise do not have the effect of causing pressure on the display. Therefore, the pen writing mode can distinguish the effect of the touch signal from the finger and the stylus. The specific driving method of the pen writing mode is not limited to the above, as long as it allows the display to produce a corresponding response on the display surface according to the stylus.

In another embodiment, the color electrophoretic display has an electromagnetic sensing layer, which usually includes a magnetic film and an electrode grid, and the stylus held by the user includes a sensing coil, so the movement of the coil can be converted into position, pressure, etc. sensed by the electromagnetic sensing layer during writing, thereby achieving the function of pen input; in this embodiment, a passive stylus (i.e., a stylus without an internal power supply) can be used, and its electric field can be sensed by the electromagnetic sensing layer. This embodiment can determine the start or end of the input stroke by analyzing the pressure/electromagnetic signal data from the electromagnetic sensing layer. For example, a pressure change from less than or equal to zero to greater than zero can be regarded as the start of a new stroke, and a pressure change from greater than zero to less than or equal to zero indicates the end of this stroke.

In step S1, when the stylus tip approaches the color electrophoretic display 100, 100a, the stylus generates a response signal, such as an electric field synchronized with the oscillation of the resonant circuit of the electromagnetic induction layer, so that the tip of the stylus approaches (but does not touch) the color electrophoretic display, and the pen writing mode can be automatically turned on. Alternatively, the pen writing mode can be turned on by the user selecting a menu with the stylus or finger.

In step S2, the pen writing color is specified. The pen writing color can be one or more of the multiple colors that can be presented by the aforementioned colored particles and non-colored particles. The specific number of colors that can be presented depends on the color electrophoresis display used, but does not include black and white (non-color) because the delay of single color, such as black and white (non-color) color presentation is not high. For example, the position of the particles is controlled by the extreme driving method described above. Therefore, when the user specifies the pen stroke color as black or white, the color electrophoresis display can directly display the pen stroke with the specified color without the need to perform the following color matching step.

Generally speaking, when the update rate of the color specified by the user is low (i.e., the update time is long), the color matching method of the present invention can be used; conversely, if the update rate of the color specified by the user is high (e.g., higher than the update rate that can be recognized by the human eye), the pen strokes can be directly displayed. Specifically, the color electrophoresis display of this embodiment has an internal lookup table (the data can be stored in the memory of the display), which records the update time of each color of the display. After the user specifies the color, the controller of the color electrophoresis display will perform a comparison step to find the update time of the specified color. If the update time exceeds a certain value (e.g., greater than 20 milliseconds, greater than 30 milliseconds, greater than 42 milliseconds, greater than 65 milliseconds, greater than 100 milliseconds), the color matching method of the present invention can be used. In a specific embodiment, when the update time of a specified color is greater than 50 milliseconds, the controller of the color electrophoresis display does not directly output the pen track, but performs the following pen color matching steps.

Refer to FIG. 5. FIG. 5 is a schematic diagram of the middle step of the display method of FIG. 4. In step S3, the stylus 200 contacts the color electrophoretic display or moves on the color electrophoretic display to output a black pen track 210; the term "black pen track" in this embodiment does not limit the color of the handwriting to pure black defined optically, such as K=100 in the CMYK system. The term "black pen track" is mainly for the convenience of explanation: the handwriting colors presented in step S3 and step S4 are different (that is, to the human eye, one is colorless and the other is colored). As shown in FIG. 3D, the three colored particles are all located above the white particles 142 after mixing, and are displayed as black (please note that although the black in this embodiment is formed by mixing colors, from the user's perspective, it is still a single color (colorless)). In this embodiment, the pixels passed by the stylus 200 are displayed in black according to the aforementioned driving method, rather than directly displaying the pen writing color specified in step S2. Therefore, less than 50 milliseconds of reaction time are required in step S3. As mentioned above, the four particles of white particles 142, cyan particles 144, yellow particles 146, and magenta particles 148 are driven by the maximum voltage difference and move to the top electrode 130 at the fastest speed for light mixing, so that the pen strokes can be drawn with the minimum reaction time, so that the human eye cannot feel the delay.

Alternatively, the above four particles can be made magnetic, so that a mixed driving mode can be used, that is, in addition to the electric field, a magnetic field can be incorporated, and the above particles can also be driven to move to the top electrode 130 at the fastest speed for light mixing.

The pixel of the black pen track 210 shown in FIG5 can refer to FIG3D. The cyan particles 144, yellow particles 146 and magenta particles 148 in the pixel corresponding to the black pen track 210 all move above the white particles 142.

In general, step S3 is to use the color with the fastest update speed in the color electrophoresis display to preferentially present the trajectory formed by the movement of the pen, so that the user can instantly see the position/state of the pen writing when writing. As mentioned above, the color electrophoresis display includes a lookup table, which can record the update time of each color of the display, so the control chip of the color electrophoresis display can select the color with the fastest update speed from the lookup table to preferentially present the pen stroke. There is a distance between the tip of the user's touch pen/stylus and the front end point of the pen stroke track output by the color electrophoretic display. This distance can also represent the delay mentioned above. The present embodiment can significantly reduce the distance so that the two are located in the same position as much as possible. The size of the distance is positively correlated with the writing speed and the delay time. Under the condition of a fixed writing speed, the color with the fastest update speed (i.e. the shortest delay time) is selected to preferentially present the pen stroke, which can significantly shorten the aforementioned distance and thus better meet the needs of pen writing. In this embodiment, since black is the display color with the highest update speed (50 milliseconds), this embodiment uses black as the presentation color of the pen strokes. The general writing speed is about 60mm/second. After calculation, the aforementioned spacing is about 3mm, which means that if the spacing can be controlled below 3mm, the writing delay can be effectively reduced.

Refer to FIG. 6. FIG. 6 is a schematic diagram of the middle step of the display method of FIG. 4. Then, in step S4, the handwriting pen 200 is sensed to move away or stop moving, and the black pen writing track 210 is converted into a color pen writing track 220 of the designated pen writing color selected in step S2. For example, the stroke is determined to have ended by using the decrease in the pressure value, and the black pen writing track 210 is overprinted so that the pen stroke presents the color selected by the user. In this embodiment, the pixels passed by the handwriting pen 200 are displayed as the pen writing color specified in step S2 according to the aforementioned driving method. FIG. 6 is a schematic diagram of the pixels of the color pen writing track 220, and its color particle distribution can refer to the red color in FIG. 3C as an example, but is not limited to this. The color pen trace 220 can be a combination of one or more colors, which is the color presented by the cyan particles 144, yellow particles 146, magenta particles 148 and white particles 142 moving to the top electrode in the driving mode and reflecting the external light source or the system built-in light source; and the color of the designated pen writing and the color of the black pen writing trace have a change in brightness and at least one of the changes in hue and chroma. For example, the present embodiment changes from black to red, which has changes in brightness, hue, and chroma in color science. Compared with the present case, the gray/grayscale presented in the previous case during the movement of the black and white particles only has a change in brightness, and the grayscale of the black and white particle system is a natural phenomenon that does not require special control.

Since the black pen track 210 (e.g., the color with the fastest update speed) is displayed first in step S3, the user will not feel the delay of the pen track. Step S4 is immediately after step S3, so although it takes about 500 milliseconds (depending on the specified color), when the black pen track 210 already exists, the time delay of displaying the colored pen track 220 may be less obvious, thereby improving the user experience. In one embodiment, the color selected in step S3 updates faster than the color specified in step S2. Specifically, the update time of the color specified in step S2 is approximately 5 to 10 times longer than the update time of the color selected in step S3. For example, the update time of black in this embodiment is 50 milliseconds, while red requires 500 milliseconds.

In a variation, in order to avoid a large difference between the color presented in priority in step S3 and the color selected by the user in step S2, the color presented in priority in step S3 will be selected to be close to the color selected by the user in step S2 under the premise of reducing the delay. Taking color difference as a factor of consideration, if the ΔE of two colors is less than 3.2, the human eye cannot distinguish the two colors; if 3.2＜ΔE＜6.5 of the two colors, the human eye will think that the two colors are basically the same; if 6.5＜ΔE＜13 of the two colors, the human eye will think that the two colors are the same color tone; if ΔE of two colors is greater than 13, the human eye will think that the two colors are different colors. Therefore, when the user selects a certain color (step S2), the control chip of the color electrophoretic display can perform the following sub-steps: determine whether the color difference between the designated pen writing color and the color of the black pen writing track is greater than 13, and if so, perform the following steps: find a color group from the lookup table whose ΔE between the color selected by the user is less than 13 (in other embodiments, it can also be set to be less than 6.5 or less than 3.2), and then select the color with the fastest update speed from the group to present the pen stroke: or if the ΔE between the color in the lookup table and the color selected by the user is greater than 13 (in other embodiments, it can also be set to be greater than 6.5 or greater than 3.2), then directly use the color with the fastest update speed to present the pen stroke. Based on this, the pen writing delay can be reduced, and the visual discomfort of the user to the pen stroke color switching can be reduced.

In some embodiments, an electrophoretic display having particles of four or more colors may also be used. Since the display method disclosed herein first displays the black pen track 210 and then displays the designated color, the time required for adjusting the multi-color particles in step S3 is not limited, and the effect of enhancing the user experience can still be achieved.

The present disclosure provides another embodiment of a display method of a color electrophoretic display. In this embodiment, the difference from the above embodiment is that the step of specifying the pen writing color can be specified after the black pen writing track 210 is completed.

The above-mentioned step of converting the black pen track 210 into the colored pen track 220 includes hue conversion. Hue conversion is the aforementioned step of changing the arrangement position of the colored particles. In some embodiments, it also includes brightness conversion and chroma conversion. The brightness conversion can be determined by the position of the white particles 142 as the reflective layer. The chroma conversion can be determined by the position of the colored particles.

In summary, the display method of the color electrophoretic display disclosed in the present invention is to display the black pen track first, and the user will not feel the problem of pen track delay. After displaying the pen track, the color development step is performed. In the state where the black pen track already exists, the time delay of displaying the color can be less obvious, so it can have the effect of improving the user experience. Therefore, the display method of the color electrophoretic display disclosed in the present invention provides a method for reducing the pen track delay and providing the effect of color handwriting at the same time. However, another implementation method of the color electrophoretic display is to use a color filter to produce the three primary colors, and then mix the light to present a color display. The color development of this color electrophoretic display does not involve the movement of multi-color particles, so the color matching method of the present invention may not be applicable to an electrophoretic display with a color filter (but this article does not exclude it).

The present invention mainly utilizes the step of color matching to solve the color display delay problem caused by the movement of each colored particle in a multi-color particle system. In the writing stage, the color with the shortest update time is used to present the writing track, so that the user does not feel the delay. For example, the distance between the tip of the user's touch pen/stylus and the front end point of the pen track output by the color electrophoresis display is limited to less than 3mm, and then the specified color is applied to the pen track to present the user's pre-selected handwriting color.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present disclosure. Anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be determined by the scope of the attached patent application.

100,100a: Color electrophoretic display 110: Substrate 120: Bottom electrode 130: Top electrode 140: Electrophoretic medium 142: White particles 144: Cyan particles 146: Yellow particles 148: Magenta particles 150,160: Adhesive layer 170: Protective layer 200: Stylus pen 210: Black pen writing track 220: Color pen writing track S1~S4: Steps

FIG. 1 is a cross-sectional view of a color electrophoresis display according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view of a color electrophoresis display according to an embodiment of the present disclosure. FIG. 3A to FIG. 3D are schematic diagrams of the positions of different particles when a color electrophoresis display according to an embodiment of the present disclosure displays different colors. FIG. 4 is a display method of a color electrophoresis display according to an embodiment of the present disclosure. FIG. 5 is a schematic diagram of an intermediate step of the display method of FIG. 4. FIG. 6 is a schematic diagram of an intermediate step of the display method of FIG. 4.

S1~S4: Steps

Claims (10)

A display method of a color electrophoretic display, wherein the color electrophoretic display comprises a non-color particle and a plurality of color particles, and the display method of the color electrophoretic display comprises: S1: Turning on the pen writing mode; S2: Providing a designated pen writing color; S3: Sensing the movement of a stylus pen to output a black pen writing track, wherein the color of the black pen writing track is presented by the non-color particle and the color particles being close to a top electrode, and the color update time of the black pen writing track is less than 50 milliseconds; and S4: Sensing the stopping of the stylus pen, converting the black pen writing track into a color pen writing track having the designated pen writing color, and the designated pen writing color and the color of the black pen writing track have a change in brightness and a change in at least one of hue and chroma. A display method of a color electrophoresis display as described in claim 1, wherein the color of the black pen writing track is the color with the shortest update time in the color electrophoresis display. A display method of a color electrophoretic display as described in claim 1, wherein the update time of the designated pen writing color is 5 to 10 times the update time of the color of the black pen writing track. A display method of a color electrophoretic display as described in claim 1, wherein the non-color particles are white, and the color particles are cyan, yellow and magenta. A display method of a color electrophoretic display as described in claim 1, wherein the distance between the black pen writing track and the tip of the stylus pen is less than 3 mm. The display method of the color electrophoresis display as described in claim 1 further includes: Determining whether the color difference between the designated pen writing color and the color of the black pen writing trace is greater than 13; if so, then: Selecting a color group whose color difference with the designated pen writing color is less than 13, and then selecting a color with the shortest update time from the group, and presenting the pen writing trace with the color in step S3. In the display method of the color electrophoretic display as described in claim 1, step S3 further includes using the pressure between the stylus pen and the color electrophoretic display to change from low to high to sense that the stylus pen touches the color electrophoretic display and starts to move. In the display method of the color electrophoretic display as described in claim 1, step S4 further includes using the pressure between the stylus pen and the color electrophoretic display to change from high to low to sense that the stylus pen is moving away and stops. A display method of a color electrophoretic display as described in claim 1, wherein step S2 is before or after step S3. A color electrophoretic display comprises a non-color particle and a plurality of color particles. The non-color particle and the color particles are close to a top electrode to present a pen track formed by the movement of a stylus. The distance between the end point of the pen track and the tip of the stylus is less than 3 mm. The color electrophoretic display does not include a color filter.

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