Electrophoretic display device and driving method

Abstract

The application discloses an electrophoretic display device, and relates to the electrophoretic display field, and comprises an electrophoretic display unit, a refractive layer and an ultraviolet light source layer; an ultraviolet light source device area of the ultraviolet light source layer is arranged in opposite corner areas of the electrophoretic display unit, and the ultraviolet light source device area of the ultraviolet light source layer is provided with an ultraviolet light emitting diode; wherein fluorescent electrophoretic particles of the electrophoretic display unit are excited to fluoresce under ultraviolet irradiation; an anode, a UV light emitting layer and a cathode of the ultraviolet light emitting diode are arranged in a slant stack mode; UV light first passes through a transparent electrode, then passes through the refractive layer, and then is refracted to the electrophoretic display unit due to the change of the refractive index from high to low, and then photo luminescence occurs, and finally the light is emitted through a display window area. In addition, the application further discloses a driving method of the electrophoretic display. The application provides the ultraviolet light source for the electrophoretic particles of the electrophoretic display layer by arranging the UV diode light source on the side of the electrophoretic display, excites fluorescence, and effectively improves the brightness of the electrophoretic display layer and the uniformity of light emission.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photoelectric display, in particular to an electrophoretic display device and a driving method. BACKGROUND

[0002] With the rapid development of display technology, various types of information display devices gradually enter the market, including liquid crystal displays, electroluminescent displays and electrophoretic displays. Among them, electrophoretic display is to display letters, numbers and images by reflecting ambient light. In addition, the total internal reflection of the electrophoretic display screen has low energy consumption, is convenient for environmental protection and reduces the damage of blue light to the eyes. In recent years, electrophoretic display screen has been more and more applied.

[0003] At present, the electronic ink screen on the market usually uses a side-in backlight panel as a light source. The light emitted by the side-in backlight panel is reflected by the electronic ink screen and then enters the human eye, so that the display content on the screen can be observed by the human eye. However, due to the structure of the side-in backlight panel, the light source must be installed on one side of the side-in backlight panel. The light propagation process from the light source to the electrophoretic display unit is always disordered, which causes the end of the side-in backlight panel close to the light to be bright and the end far away from the light source to be dark, resulting in poor brightness uniformity and affecting the display effect of the electrophoretic display screen. In addition, the commonly used side-in backlight panel often uses white light as a supplementary light source, which increases the number of incident light rays of the electrophoretic display unit and further increases the number of light rays incident into the human eye. The brightness of the electrophoretic display screen is not greatly improved, which is not conducive to people using the electrophoretic display screen in an environment without sunlight or artificial light source.

[0004] In addition, as disclosed in Chinese Patent CN202411328802.5, a kind of color fluorescent particle for electrophoretic display and its preparation method are provided. The color fluorescent particle provided by the patent also needs a UV light source to excite fluorescence. However, when the traditional side-in backlight panel reaches the corresponding pixel point, the brightness and uniformity of the light emitted are poor. SUMMARY

[0005] In view of the shortcomings of the prior art, the primary object of the present application is to make up for the shortcomings of the prior art and provide an electrophoretic display device, which aims to provide a UV diode light source on the side of the electrophoretic display light-emitting side to provide a UV light source for the electrophoretic particles of the electrophoretic display layer and excite fluorescence, thereby effectively improving the brightness and uniformity of the light emitted by the electrophoretic display layer.

[0006] To achieve the above object, in a first aspect of the present application, an electrophoretic display device is provided, which comprises an electrophoretic display layer comprising an electrophoretic display unit, an ultraviolet light source layer, and a refractive layer arranged between the electrophoretic display unit and the ultraviolet light source layer, the ultraviolet light source layer comprising a display window area and an ultraviolet light source device area, the ultraviolet light source device area being arranged at a corner area opposite to the electrophoretic display unit, and the ultraviolet light source device area being provided with an ultraviolet light emitting diode; wherein the electrophoretic display unit comprises fluorescent electrophoretic particles, and the fluorescent electrophoretic particles are excited to fluoresce under ultraviolet irradiation.

[0007] The ultraviolet light emitting diode comprises an anode, a UV light emitting layer, and a cathode, wherein the anode is located on a side close to the electrophoretic display unit, the UV light emitting layer is located between the anode and the cathode, and the cathode is located on a light emitting side of the device; wherein the anode is a transparent electrode, and the cathode is an opaque electrode.

[0008] The anode, the UV light emitting layer, and the cathode are arranged in a slant stack, and a first pointing direction downstream of the cathode, the UV light emitting layer, and the anode is the electrophoretic display unit, the light emitting direction of the ultraviolet light emitting diode is inclined towards the electrophoretic display unit, the refractive index of the refractive layer is less than the refractive index of the transparent electrode, the UV light emitted by the ultraviolet light emitting diode first passes through the transparent electrode and then passes through the refractive layer to cause a light dense to light sparse refraction, and the UV light is deflected to the electrophoretic display unit and causes photoluminescence, and is emitted through the display window area.

[0009] In a specific embodiment, the thickness of the refractive layer is greater than or equal to the thickness of the anode; the thickness of the anode is 10 nm-50 nm, and the thickness of the refractive layer is 50 nm-200 μm.

[0010] In a specific embodiment, one ultraviolet light source device area corresponds to two electrophoretic display units, and the ultraviolet light source device area is located between the two electrophoretic display units; the ultraviolet light emitting diode of the ultraviolet light source device area comprises a common cathode, a first UV light emitting layer, a second UV light emitting layer, a first anode, and a second anode; the common cathode, the first UV light emitting layer, and the first anode are arranged in a slant stack, and a second pointing direction downstream of the common cathode, the first UV light emitting layer, and the first anode is a first electrophoretic display unit; the common cathode, the second UV light emitting layer, and the second anode are arranged in a slant stack, and a third pointing direction downstream of the common cathode, the second UV light emitting layer, and the second anode is a second electrophoretic display unit.

[0011] In an embodiment, the device comprises a plurality of ultraviolet light emitting diodes, the electrophoretic display unit comprises a plurality of electrophoretic pixels, the types of the electrophoretic pixels comprise red pixel units, green pixel units and / or blue pixel units, and the ultraviolet light emitting diodes are arranged diagonally to each of the electrophoretic pixels.

[0012] In an embodiment, the first anode and the second anode are connected to an independent positive power potential signal line.

[0013] In an embodiment, the material of the anode comprises one or more than two combinations of indium tin oxide film, aluminum-doped zinc oxide film, fluorine-doped tin oxide film, graphene film, carbon nanotube film, metal mesh film, and conductive polymer film.

[0014] In a second aspect of the present application, a driving method of an electrophoretic display is provided, which is applied to the electrophoretic display device provided in the first aspect of the present application, and the method comprises:

[0015] In response to a first driving signal, the electrophoretic display unit is driven to present a letter, an image, or a number.

[0016] In response to a second driving signal, a plurality of ultraviolet light emitting diodes in the ultraviolet light source layer are driven to emit light, wherein the UV light emitted by the ultraviolet light emitting diodes is first refracted by the transparent electrode and then by the refractive layer to change from light dense to light sparse, and then the light is deflected to the electrophoretic display unit and undergoes photoluminescence, and finally the light is emitted through the display window area.

[0017] In an embodiment, the process of driving the plurality of ultraviolet light emitting diodes in the ultraviolet light source layer to emit light comprises: monitoring the light intensity of the external environment light, when the monitored light intensity is greater than or equal to a light intensity threshold, the ultraviolet light emitting diodes are not driven to emit light, and when the monitored light intensity is less than the light intensity threshold, the ultraviolet light emitting diodes are driven to emit light.

[0018] The beneficial effects of the present application are: 1) the present application provides a UV light source for the electrophoretic particles of the electrophoretic display layer by arranging a UV diode light source on the light side of the electrophoretic display, and excites fluorescence, effectively improving the brightness and uniformity of the electrophoretic display layer. 2) In the present application, the anode of the ultraviolet light emitting diode is located on the side close to the electrophoretic display unit, the anode is a transparent electrode, and the corresponding cathode is an opaque electrode; on the one hand, the cathode can effectively block the ultraviolet light from shining on the light side, on the other hand, it can improve the irradiation amount to the electrophoretic display layer, in addition, considering that the LED light direction is inclined to the anode of the PN junction, so the anode of the ultraviolet light emitting diode is also close to the electrophoretic display unit. 3) In the present application, the anode, the UV light emitting layer and the cathode are arranged in a slanting stack, and the downstream of the first pointing direction from the cathode, through the UV light emitting layer and the anode is the electrophoretic display unit, the light emitting direction of the ultraviolet light emitting diode is inclined to the electrophoretic display unit, the refractive index of the refractive layer is less than the refractive index of the transparent electrode, and the UV light emitted by the ultraviolet light emitting diode first passes through the transparent electrode and then the refractive layer to occur light dense to light sparse refraction and be deflected to the electrophoretic display unit and occur photoluminescence, and is emitted through the display window area. In the UV-LED, the electron and hole are combined in a slanting stack motion direction controlled by the anode and cathode voltage, and mainly emit light along the electron motion direction, and the light is inclined; then the anode / refractive layer interface occurs from light dense to light sparse deflection and irradiates the electrophoretic display unit, realizes UV-LED light source regulation, effectively ensures UV irradiation, improves the light emitting window opening rate of the electrophoretic display window, and reduces the shielding of the UV-LED. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A structure schematic diagram of an electrophoretic display device provided in another specific embodiment of the present application is provided.

[0020] Figure 2 A structure schematic diagram of an electrophoretic display device of a single ultraviolet light source device area double ultraviolet LED provided in another specific embodiment of the present application is provided.

[0021] Figure 3 A structure schematic diagram of a red, green and blue three primary color electrophoretic display device provided in another specific embodiment of the present application is provided. DETAILED DESCRIPTION

[0022] The embodiments of the present patent are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present patent, and cannot be understood as a limitation of the present patent.

[0023] As Figures 1-3As shown in the first embodiment of the present application, an electrophoretic display device is provided, which comprises an electrophoretic display layer 100 comprising an electrophoretic display unit 101, an ultraviolet light source layer 200, and a refractive layer 300 arranged between the electrophoretic display unit 101 and the ultraviolet light source layer 200, wherein the ultraviolet light source layer 200 comprises a display window area 201 and an ultraviolet light source device area 202, the ultraviolet light source device area 202 is arranged at a corner area opposite to the electrophoretic display unit 101, and the ultraviolet light source device area 202 is provided with an ultraviolet light emitting diode 203; wherein the electrophoretic display unit 101 comprises fluorescent electrophoretic particles 102, and the fluorescent electrophoretic particles 102 are excited to fluoresce under ultraviolet irradiation.

[0024] The ultraviolet light emitting diode 203 comprises an anode 204, an UV light emitting layer 205, and a cathode 206, wherein the anode 204 is arranged close to the electrophoretic display unit 101, the UV light emitting layer 205 is arranged between the anode 204 and the cathode 206, and the cathode 206 is arranged at the light exit side of the device; wherein the anode 204 is a transparent electrode, and the cathode 206 is an opaque electrode.

[0025] The anode 204, the UV light emitting layer 205, and the cathode 206 are arranged in a slant stack, and the electrophoretic display unit 101 is arranged downstream of the cathode 206 in a first pointing direction, the light emitting direction of the ultraviolet light emitting diode 203 is inclined towards the electrophoretic display unit 101, the refractive index of the refractive layer 300 is less than the refractive index of the transparent electrode, the UV light emitted by the ultraviolet light emitting diode 203 is first refracted by the transparent electrode and then by the refractive layer 300, and then the light is refracted from the dense to the sparse, and then the light is deflected to the electrophoretic display unit 101 and then the light is photo-luminescent, and then the light is emitted through the display window area 201.

[0026] Further, the thickness of the refractive layer 300 is greater than or equal to the thickness of the anode 204; the thickness of the anode 204 is 10 nm-50 nm, and the thickness of the refractive layer 300 is 50 nm-200 μm.

[0027] Preferably, the anode 204 is an ITO thin film with a thickness of 20 nm-30 nm.

[0028] It is worth mentioning that, in the present embodiment, in the PN junction region of the ultraviolet light emitting diode 203, the movement direction of the electrons is related to the position of the cathode 206 and the anode 204, i.e. due to the fact that the anode 204, the UV light emitting layer 205 and the cathode 206 are arranged in a slant stack in the present embodiment, the movement direction of the electrons and holes in the PN junction region also conforms to the direction of movement; the ultraviolet light generated by the recombination of the electrons and holes is emitted out of the anode 204 composed of a transparent conductive material, and due to the fact that the refractive index of the refractive layer 300 is less than the refractive index of the transparent electrode, the UV light emitted by the ultraviolet light emitting diode 203 is first refracted by the transparent electrode and then by the refractive layer 300, and then the light is refracted to the electrophoretic display unit 101 and photo luminescence occurs, and is emitted out of the display window area 201. The movement direction of the ultraviolet light source outside the anode 204 is mainly affected by optical refraction and transmission.

[0029] In a typical example, one ultraviolet light emitting diode 203 corresponds to one pixel of the electrophoretic display unit 101; and in an alternative embodiment, the ultraviolet light source device area 202 can be arranged between two pixels of the electrophoretic display unit 101, and the ultraviolet light source can be provided to the two electrophoretic display pixels respectively.

[0030] For example Figure 2 As shown in an alternative embodiment, one ultraviolet light source device area 204 corresponds to two electrophoretic display units, and the ultraviolet light source device area 204 is located between the two electrophoretic display units; the ultraviolet light emitting diode of the ultraviolet light source device area 204 includes a common cathode 207, a first UV light emitting layer 208, a second UV light emitting layer 209, a first anode 210, and a second anode 211; the common cathode 207, the first UV light emitting layer 208, and the first anode 210 are arranged in a slant stack, and the first electrophoretic display unit 103 is located directly downstream of the second pointing direction from the common cathode 207, through the first UV light emitting layer 208 and the first anode 210; the common cathode 207, the second UV light emitting layer 209, and the second anode 211 are arranged in a slant stack, and the second electrophoretic display unit 104 is located directly downstream of the third pointing direction from the common cathode 207, through the second UV light emitting layer 209 and the second anode 211.

[0031] As Figure 3 shown, in a typical embodiment, the device includes a plurality of ultraviolet light emitting diodes 203, the electrophoretic display unit 101 includes a plurality of electrophoretic pixels, the types of the electrophoretic pixels include red pixel units, green pixel units, and / or blue pixel units, and the ultraviolet light emitting diode 203 is arranged diagonally to each of the electrophoretic pixels.

[0032] In this embodiment, the first anode 204 and the second anode 204 are connected to independent positive power potential signal lines. This facilitates separate control and facilitates brightness regulation.

[0033] Typically, the material of the anode 204 includes one or a combination of more than two of indium tin oxide film, aluminum-doped zinc oxide film, fluorine-doped tin oxide film, graphene film, carbon nanotube film, metal mesh film, and conductive polymer film.

[0034] The electrophoretic display device provided by the first embodiment of the present application can be effectively applied to Chinese Patent CN202411328802.5. When ultraviolet light or natural light such as sunlight emitted by the UV light source layer is incident on the electrophoretic display layer 100, photo-induced luminescence phenomenon occurs on the surface of the electrophoretic particles. After these light rays are reflected on the surface of the electrophoretic particles, they are emitted through the top transparent electrode, thereby producing a display effect with high brightness and high uniformity. The electrophoretic display technology of the present application achieves an optimized visual effect by precisely controlling the intensity and color output of various light sources. This technology not only significantly improves the brightness of electronic paper, but also ensures the uniformity of the displayed content at different viewing angles. In addition, the design of this system also takes into account energy efficiency, effectively reducing energy consumption by using ultraviolet light-emitting diodes. The present application brings innovative improvements to electrophoretic display technology, making it more widely and efficiently applied in the modern display field.

[0035] It is worth mentioning that when driving the electrophoretic display layer 100 to present an image, based on the principle of electrophoretic display, the colored electrophoretic particles in the electrophoretic display layer 100 are driven to move back and forth. For example, when the red electrophoretic particles are driven to move close to the light-emitting side, the position presents red color, and when the white electrophoretic particles are driven to move to the light-emitting side, the position presents white color. By driving the movement of electrophoretic particles of different colors at different electrophoretic pixels, the electrophoretic display screen presents different pictures such as letters, numbers, and images. At the same time, in dark conditions or insufficient light, the ultraviolet light source layer 200 can turn on the UV light, photo-induced excitation of electrophoretic particles, improve the brightness of electrophoretic particles, and then increase the diffuse reflection light, realize electrophoretic display in dark environment or insufficient light environment.

[0036] According to the light-emitting principle of the ultraviolet light source layer 200, a positive driving signal is provided to the anode 204 of the ultraviolet light-emitting diode 203, and a negative driving signal is provided to the cathode 206 to drive the ultraviolet light-emitting diode 203 to emit light. The UV light emitted by the ultraviolet light-emitting diode 203 is incident on the electrophoretic display layer 100 and undergoes photo-induced luminescence. The red, green, and blue light after diffuse reflection is emitted through the red, green, and blue display window areas 201 into the human eye, so that the user can see the letters, numbers, images, and other pictures presented by the electrophoretic display screen.

[0037] Compared with the side-in light guide plate in the prior art, the ultraviolet light source layer 200 provided by the embodiment of the present application is used as the light source of the electrophoretic display, the brightness uniformity of the electrophoretic display light source is improved, and then the brightness uniformity of the picture presented by the electrophoretic display screen is improved, and the user's viewing experience is improved.

[0038] Referring again to Figure 1 , the cathode 206 is an opaque electrode. In this way, on the one hand, it can be ensured that the ultraviolet light cannot be emitted through the cathode 206, avoiding the interference of the light emitted by the ultraviolet light-emitting diode 203 directly emitted to the human eye, and affecting the display effect of the electrophoretic display; on the other hand, a small amount of light emitted by the ultraviolet light-emitting diode 203 towards the cathode 206 can be reflected to the anode 204 by the cathode 206 and emitted through the anode 204, thereby improving the light emission rate of the ultraviolet light-emitting diode 203.

[0039] Optionally, the ultraviolet light-emitting diode 203 is a passive electrically excited ultraviolet light-emitting diode 203, and when driving the passive electrically excited ultraviolet light-emitting diode 203 to emit light, only the corresponding driving signal needs to be directly provided to the anode 204 and the cathode 206, without the need for driving by a driving transistor. Therefore, by setting the ultraviolet light-emitting diode 203 in the ultraviolet light source layer 200 as a passive electrically excited ultraviolet light-emitting diode 203, the ultraviolet light source layer 200 only needs to be provided with the anode 204, the light-emitting layer and the cathode 206, without the need for a driving transistor, thereby reducing the thickness of the ultraviolet light source layer 200 and greatly reducing the manufacturing cost.

[0040] In the second embodiment of the present application, a driving method of an electrophoretic display is provided, and the method is applied to the electrophoretic display device provided in the first embodiment. The method comprises the following steps:

[0041] In response to a first driving signal, the electrophoretic display unit is driven to present a letter, an image or a number;

[0042] In response to a second driving signal, a plurality of ultraviolet light-emitting diodes in the ultraviolet light source layer are driven to emit light; wherein the UV light emitted by the ultraviolet light-emitting diode first passes through the transparent electrode and then passes through the refractive layer to cause light density to light density refraction and deflection to the electrophoretic display unit and photo-induced luminescence, and is emitted through the display window area.

[0043] In this embodiment, the process of driving the plurality of ultraviolet light-emitting diodes in the ultraviolet light source layer to emit light comprises: monitoring the light intensity of the external ambient light, when the monitored light intensity is greater than or equal to a light intensity threshold, the ultraviolet light-emitting diodes are not driven to emit light, and when the monitored light intensity is less than the light intensity threshold, the ultraviolet light-emitting diodes are driven to emit light.

[0044] The preferred embodiments of the present application have been described above in detail. It should be understood that modifications and variations to the present application can be affected by those skilled in the art without departing from the scope of the application. Accordingly, it is intended that all possible modifications and alterations be included within the scope of the present application as defined by the following claims.

Claims

1. An electrophoretic display device, characterized in that, The device includes: an electrophoretic display layer containing an electrophoretic display unit, an ultraviolet light source layer, and a refractive layer disposed between the electrophoretic display unit and the ultraviolet light source layer. The ultraviolet light source layer includes a display window area and an ultraviolet light source device area. The ultraviolet light source device area is disposed in the corner area opposite to the electrophoretic display unit, and an ultraviolet light-emitting diode is disposed in the ultraviolet light source device area. The electrophoretic display unit contains fluorescent electrophoretic particles, which exhibit fluorescence color development under ultraviolet irradiation. The ultraviolet light-emitting diode includes an anode, a UV light-emitting layer, and a cathode. The anode is located near the electrophoretic display unit, the UV light-emitting layer is located between the anode and the cathode, and the cathode is located on the light-emitting side of the device. The anode is a transparent electrode, and the cathode is an opaque electrode. The anode, the UV emitting layer, and the cathode are arranged in an oblique stack. The electrophoretic display unit is located downstream of the cathode, through the UV emitting layer, and the anode in a first pointing direction. The light emission direction of the ultraviolet light-emitting diode is tilted and directed towards the electrophoretic display unit. The refractive index of the refractive layer is less than that of the transparent electrode. The UV light emitted by the ultraviolet light-emitting diode first passes through the transparent electrode and then through the refractive layer, undergoing refraction from denser to less dense, and is deflected to the electrophoretic display unit, where photoluminescence occurs. The light then exits through the display window area. In this configuration, one ultraviolet light source device area corresponds to two electrophoretic display units, and the ultraviolet light source device area is located between the two electrophoretic display units. The ultraviolet light-emitting diode in the ultraviolet light source device area includes a common cathode, a first UV light-emitting layer, a second UV light-emitting layer, a first anode, and a second anode. The common cathode, the first UV light-emitting layer, and the first anode are arranged in an oblique stack, and the first electrophoretic display unit is located downstream of the common cathode and in a second pointing direction formed by the first UV light-emitting layer and the first anode. The second electrophoretic display unit is located downstream of the common cathode and in a third pointing direction formed by the second UV light-emitting layer and the second anode.

2. The electrophoretic display device as described in claim 1, characterized in that, The thickness of the refractive layer is greater than or equal to the thickness of the anode; the thickness of the anode is 10nm-50nm, and the thickness of the refractive layer is 50nm-200μm.

3. The electrophoretic display device as described in claim 1, characterized in that, The device includes multiple ultraviolet light-emitting diodes, and the electrophoretic display unit includes multiple electrophoretic pixels. The types of electrophoretic pixels include red pixel units, green pixel units, and / or blue pixel units. The ultraviolet light-emitting diodes are arranged diagonally with each of the electrophoretic pixels.

4. The electrophoretic display device according to claim 1, characterized in that, The first anode and the second anode are connected to an independent positive power supply potential signal line.

5. The electrophoretic display device as described in claim 1, characterized in that, The anode material includes one or more of the following: indium tin oxide thin film, aluminum-doped zinc oxide thin film, fluorine-doped tin oxide thin film, graphene thin film, carbon nanotube thin film, metal mesh thin film, and conductive polymer thin film.

6. A driving method for electrophoretic display, characterized in that, The method is applied to an electrophoretic display device as described in any one of claims 1-5, the method comprising: In response to the first driving signal, the electrophoretic display unit is driven to display letters, images, and numbers; In response to the second driving signal, multiple ultraviolet light-emitting diodes in the ultraviolet light source layer are driven to emit light; wherein, the UV light emitted by the ultraviolet light-emitting diodes first passes through the transparent electrode and then through the refractive layer, undergoing refraction from optical density to optical sparseness, and is deflected to the electrophoretic display unit to generate photoluminescence, and is emitted through the display window area.

7. The driving method according to claim 6, characterized in that, The process of driving multiple ultraviolet light-emitting diodes in the ultraviolet light source layer to emit light includes: monitoring the light intensity of ambient light; when the monitored light intensity is greater than or equal to a light intensity threshold, not driving the ultraviolet light-emitting diodes to emit light; and when the monitored light intensity is less than the light intensity threshold, driving the ultraviolet light-emitting diodes to emit light.

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