Electronic paper display module

Abstract

An electronic paper display module, comprising: an EPD display module, a light guide plate, a light source, a reflective tape; the light guide plate is located above the EPD display module; the light source is arranged on the side of the light guide plate; the reflective tape is arranged above the light guide plate and corresponds to the edge position of the light guide plate, and is used for reflecting the light emitted by the light source into the light guide plate; the width of the reflective tape is greater than 1.0 mm and less than 10.0 mm. By arranging the reflective tape, the brightness and uniformity can be effectively improved under the same light source condition.

Description

Technical Field

[0001] This application belongs to the field of display device manufacturing, and specifically relates to an electronic paper display module. Background Technology

[0002] Electronic paper, also known as electronic ink screen, boasts excellent characteristics such as ultra-low power consumption, continuous display without electricity, and eye protection, providing the same display effect and visual experience as paper. It consists of multiple black and white mixed electron particles enclosed in a single ink sac. Under the influence of an electric current, these ink sacs arrange and combine to form "electronic ink." Influenced by positive and negative charges, these tiny ink sacs function like a liquid, forming various characters and patterns. The core features of electronic paper are low power consumption and visual health. It can be described as a "small and beautiful" new display technology.

[0003] Electronic paper (EPD) modules do not require backlighting, a requirement determined by their imaging principle, optical characteristics, and product positioning. The imaging principle of EPD modules relies on ambient light reflection for color display; they do not emit light themselves. EPD electronic paper uses reflective display technology: internal microcapsules contain black and white charged particles. An electric field drives the particles to move up and down, relying on external light reflection to form an image in the human eye; they do not emit light themselves.

[0004] Backlights are used to supplement the light for self-emissive / transmissive screens (LCD, OLED), and are completely ineffective for reflective e-paper. Adding a backlight to an e-paper EPD module will completely destroy the core e-paper experience, resulting in a deterioration in visual quality: e-paper simulates the texture of paper, providing a near-paper reading experience under natural light; adding a backlight will cause reflections, a foggy appearance, and a grayish image, losing the paper-like effect. Contrast will drop sharply: direct backlighting will dilute the contrast between black and white, making text appear blurry and significantly reducing reading comfort.

[0005] E-paper consumes power only when refreshing the screen, and almost zero power when displaying static images, which is its biggest selling point; it is suitable for persistent display scenarios such as e-books, price tags, door signs, and labels. Adding a backlight panel and backlight circuit will continuously consume power, directly negating the low power consumption advantage and causing a precipitous drop in battery life.

[0006] In low-light scenarios, i.e., in dim light, e-paper is not visible. The industry does not use built-in backlights. The mainstream solution is to use external desk lamps or ambient lighting. Some also use external front lights: the light diffuses from the front of the screen to supplement the light, without destroying the reflection principle, and is thin, light and low power consumption.

[0007] In existing technologies, diffused supplementary light from the front of the screen also passes through a light guide plate. Near the edge of the light guide plate, due to its proximity to the light source, the angle of incidence of light is relatively small. If this angle is less than the critical angle, refraction will occur, affecting the light source output. Therefore, a black layer is usually placed near the edge of the light guide plate to absorb this portion of the light, thus reducing the output light energy. With larger screens, the light energy distribution can also become uneven. How to utilize this portion of light energy and maximize its value is a technical problem that needs to be solved.

[0008] Definitions: EPD is an abbreviation for "electronic paper display." In this application, "electronic paper master" refers to an electronic paper master display. Summary of the Invention

[0009] The technical problem this application aims to solve is to avoid the problem of placing a black layer near the edge of the light guide plate in the prior art. This black layer absorbs some of the light, resulting in reduced output light energy and uneven distribution of the screen's output light energy. This application proposes an electronic paper display module that uses reflective strips at the edge to reflect light energy that would otherwise be easily refracted and absorbed by the black layer back into the light guide plate, thereby enhancing the brightness and uniformity of the light guide plate.

[0010] The applicant, noting that light sources easily escape from the edges of the light guide plate or are absorbed by the black coating, resulting in a loss of brightness, proposes an electronic paper display module comprising: an EPD display module, a light guide plate, a light source, and a reflective strip; the light guide plate is located above the EPD display module; the light source is disposed on the side of the light guide plate; the reflective strip is located above the light guide plate, corresponding to the edge of the light guide plate, and is used to reflect the light emitted by the light source into the interior of the light guide plate; the width of the reflective strip is greater than 1.0 mm and less than 10.0 mm.

[0011] By setting up reflective strips, both brightness and uniformity can be effectively improved under the same light source conditions. After testing under various conditions, the average brightness has been improved to 14.01 and the uniformity to 88.73%, compared to the previous average brightness of 12.49 and uniformity of 84.24%.

[0012] After extensive testing, the applicant discovered that a single layer of screen printing has a certain degree of light transmittance. The applicant proposed that the reflective strip be printed on the upper layer of the light guide plate, along the edge of the light guide plate, to reflect light into the interior of the light guide plate; the reflective strip is composed of one, two, or more layers of screen printing.

[0013] By adding one or more layers of screen printing, the reflective properties of the reflective tape can be improved, as well as its weather resistance.

[0014] After repeated experiments and demonstrations, the applicant found that the reflective strip can be set on the cover plate. The applicant proposed that the cover plate also be included, which is on the upper layer of the light guide plate. The reflective strip is printed on the edge of the cover plate and is used to reflect light into the interior of the light guide plate.

[0015] By placing the cover plate on the light guide plate and printing screen printing on the cover plate before or after cutting, it can be compatible with the existing process flow with minimal changes to the existing process flow.

[0016] After repeated experiments and demonstrations, the applicant concluded that black silkscreen printing absorbs light most strongly, while other colors all possess a certain degree of reflectivity. The applicant further argued that the reflective strip in question is not black.

[0017] Black absorbs light; other colors can be set according to the needs of the display module to create the reflective screen printing layer.

[0018] After extensive testing, the applicant discovered that due to production or assembly errors, light leakage occurs at the edges of the screen, resulting in abnormal brightness at the edges. Even with a reflective layer, this cannot be completely avoided. The applicant proposes to include a shielding layer on the reflective strip to prevent light from escaping the light guide plate. The width of the shielding layer is greater than 1.0 mm and less than 12.0 mm.

[0019] By setting a shielding layer, the area around the screen where the light source is located is blocked, which greatly reduces or avoids light leakage and prevents abnormal brightness around the screen.

[0020] The applicant proposes that an aesthetic layer also be included, situated on the masking layer, with a width greater than 1.0 mm and less than 12.0 mm. This aesthetic layer allows for changes to the surrounding color, thus adapting to the aesthetic requirements of the product design.

[0021] The applicant stated that the color of the shielding layer is black. Black silkscreen printing has the function of absorbing photons, which can prevent the transmission, reflection or scattering of light, and can effectively reduce the ineffective emission of light from the edges.

[0022] The applicant proposed that the aesthetic layer be white, red, or blue. White, red, and blue are common background colors for electronic paper, which can effectively reduce the impact of surrounding elements on the overall appearance.

[0023] The applicant proposes that the aesthetic layer consists of one, two, or more screen-printed layers. Increasing the thickness of the aesthetic layer not only improves the weather resistance of the color but also reduces light transmission, decreases the thickness of the masking layer, and may even eliminate the need for the masking layer altogether. Attached Figure Description

[0024] Figure 1This is a schematic diagram illustrating the principle of light emanating from the edge. Figure 2 This is a schematic diagram illustrating the principle of setting black blocks around the screen. Figure 3 This is a schematic diagram of Example 1; Figure 4 This is a schematic diagram of Example 2; Figure 5 This is a schematic diagram of Example 3; Figure 6 This is a schematic diagram of Example 4; Figure 7 This is a top view of Embodiment 5; Figure 8 This is a top view of Embodiment 6; Figure 9 The test data did not include the reflective strip. Figure 10 These are test data for reflective strips set under the same conditions.

[0025] Figures 1 to 6 This is a cross-sectional view of an electronic paper display module. Figures 1 to 6 They are all equivalent to Figure 7 AA section view diagram. Detailed Implementation

[0026] The embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0027] It should be noted that the following description of preferred embodiments of this application does not constitute any limitation on this application. The description of preferred embodiments is merely an illustration of the general principles of this application. The embodiments described in this application are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the equipment or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and technical features numbered with Arabic numerals 1, 2, 3, etc., and designations such as "A" and "B," are used for descriptive purposes only, for ease of explanation, and do not represent a temporal or spatial order; they should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first," "second," and numbered with Arabic numerals 1, 2, 3, etc., may explicitly or implicitly include one or more of that feature. In the description of this application, "several" means two or more, unless otherwise expressly and specifically defined.

[0029] In this application, the main function of the light guide plate is to uniformly guide and diffuse the light from the side LED light source onto the entire display panel, thereby achieving uniform light emission from the screen. As light passes through the dots in the light guide plate, it is scattered or reflected. The farther away from the light source, the weaker the light intensity; therefore, more dots are needed to compensate for brightness loss, ensuring uniform light emission across the entire panel. Due to the influence of dot size and depth, and the limited density of the dots, uniform light emission is more likely to occur at the edges. In this application, the reflective strip at the edges reduces the light absorbed and refracted at the edges, reflecting this portion of the light back into the light guide plate, thereby improving the overall uniformity and brightness of the EPD display module.

[0030] Figure 1 This is a schematic diagram illustrating the principle of light emanating from the edge. For example... Figure 1 Electronic paper display modules generally include an EPD display module, a light guide plate, and a cover plate. Light sources are installed on both sides of the light guide plate. The light emitted by the light source, as shown by the red line in the figure, cannot be totally reflected in the light guide plate due to the incident angle. It is easy to be transmitted through the edge or emitted through the installation gap. This situation will affect the display effect and even interfere with the normal display.

[0031] Figure 2 This is a schematic diagram of setting a black shield around the screen; to avoid the aforementioned situation, such as... Figure 2 Typically, a black silkscreen strip is placed around the perimeter of the screen, along the edge of the cover plate, to absorb light. However, this practice of using a black silkscreen strip reduces the utilization rate of the light source.

[0032] Figure 3 This is a schematic diagram of Example 1. (As shown...) Figure 3 An electronic paper display module includes: an EPD display module, a light guide plate, and a light source; the light guide plate is located above the EPD display module; the light source is disposed on the side of the light guide plate; a reflective strip is disposed above the light guide plate, corresponding to the edge of the light guide plate, for reflecting the light emitted by the light source into the interior of the light guide plate. The periphery of the light guide plate corresponds to the side where the light source is located. Figure 3 In the design, the reflective strip is white and indicated by a light red stripe. The width of the reflective strip is greater than 1.0 mm and less than 10.0 mm.

[0033] After the white reflective strip is set, the light emitted by the light source is reflected by the white reflective strip and scattered on the dots, which improves the utilization rate of the light source.

[0034] Figure 9 The test data did not include the reflective strip. Figure 10 These are test data from reflective strips set under the same conditions; Figure 9 and Figure 10 In this model, the Lum Uni uniformity parameter is related to brightness. Lum(cd / m 2 ): Represents the brightness value at each test point on the screen, in candela per square meter (cd / m²). 2 The higher the value, the brighter the screen. The minimum brightness value in the table is 11.49 cd / m². 2 The maximum value is 13.64 cd / m 2 The average value is 12.49 cd / m³. 2 This indicates that the overall screen brightness is at a medium level, with some differences in brightness between different areas.

[0035] Lum Uniformity: 84.24% represents the consistency of brightness distribution in different areas of the screen. It is calculated as the minimum brightness ÷ the maximum brightness × 100%. The closer this value is to 100%, the better the brightness uniformity. 84.24% indicates that the screen brightness distribution is somewhat uneven, but it is at a medium to high level and there will be no obvious "yin-yang screen" problem.

[0036] Chromaticity is related to color accuracy. CIEx, CIEy, CIEu', and CIEv' are the chromaticity coordinate parameters of the screen, used to describe the position of the colors displayed on the screen. They are the basic data for judging whether the colors are accurate. Slight differences in the chromaticity coordinates at different test points indicate that there are slight differences in color performance in different areas of the screen.

[0037] Tc: Represents color temperature, measured in Kelvin (K). The higher the value, the cooler the screen tone; the lower the value, the warmer the tone. The color temperature in the table is between 4158K and 4571K, with an average of 4310.89K, which is a cool white tone, suitable for audio-visual entertainment scenarios, and can reproduce clearer and sharper images.

[0038] The test point data distribution characteristics show that the test points cover nine areas of the screen: top left, top center, top right, center left, center center, center right, bottom left, bottom center, and bottom right. This layout is designed to comprehensively test the optical performance of different locations on the screen and avoid local anomalies affecting the overall judgment. The data shows that the brightness and color temperature of the screen edge areas (such as points 1 and 3) differ somewhat from the central area, but the overall difference is within an acceptable range.

[0039] Figure 10 and Figure 9 Compared to the previous version, brightness performance has been improved. Figure 10 Overall brightness improved: average brightness increased from 12.49 cd / m². 2 Increased to 14.01 cd / m 2 The minimum brightness is 11.49 cd / m². 2 Increased to 13.38 cd / m 2 The maximum value is 13.64 cd / m 2 Increased to 15.08 cd / m 2 The overall brightness of the screen is significantly enhanced, resulting in a brighter picture.

[0040] Figure 10 and Figure 9 Compared to the previous version, brightness uniformity is improved: Lum Uni has increased from 84.24% to 88.73%, the difference between the lowest and highest brightness values ​​has narrowed, the brightness distribution in different areas of the screen is more uniform, and it can effectively reduce uneven brightness in the picture.

[0041] Figure 10 and Figure 9 Compared to the previous version, the color accuracy and color temperature performance have been optimized, and the color accuracy has been improved: the average CIEx has increased from 0.37 to 0.38, CIEy from 0.38 to 0.38, CIEu' from 0.22 to 0.22, and CIEv' from 0.5 to 0.5. The chromaticity coordinates are closer to the standard values, the color performance consistency in different areas of the screen is better, and the color reproduction is more accurate.

[0042] Figure 10 and Figure 9Compared to the previous version, the color temperature stability is enhanced: the average color temperature has increased from 4310.89K to 4181.67K, and the color temperature range has narrowed from 4158K-4571K to 4039K-4462K. The fluctuation range of color temperature is smaller, the overall color tone of the screen is more stable, and the color atmosphere of the picture is more unified.

[0043] By setting up reflective strips, both brightness and uniformity can be effectively improved under the same light source conditions. After testing under various conditions, the average brightness has been improved to 14.01 and the uniformity to 88.73%, compared to the previous average brightness of 12.49 and uniformity of 84.24%.

[0044] After extensive testing, the applicant discovered that a single layer of screen printing has a certain degree of light transmittance. The applicant proposed that the reflective strip be printed on the upper layer of the light guide plate, along the edge of the light guide plate, to reflect light into the interior of the light guide plate; the reflective strip is composed of one, two, or more layers of screen printing.

[0045] By adding one or more layers of screen printing, the reflective properties of the reflective tape can be improved, as well as its weather resistance.

[0046] Figure 4 This is a schematic diagram of Embodiment 2; after repeated experiments and demonstrations, the applicant found that the reflective strip can be set on the bottom surface of the cover plate, the cover plate is set on the upper layer of the light guide plate, and the reflective strip is printed on the edge of the cover plate to reflect light into the interior of the light guide plate.

[0047] By placing the cover plate on top of the light guide plate, and printing screen printing on the cover plate before or after cutting, it can be compatible with existing processes with minimal changes to the existing process flow.

[0048] After repeated experiments and demonstrations, the applicant concluded that black silkscreen printing absorbs light most strongly, while other colors all possess a certain degree of reflectivity. The applicant further argued that the reflective strip in question is not black.

[0049] Black absorbs light; other colors can be set according to the needs of the display module to create the reflective screen printing layer.

[0050] like Figure 4 After extensive testing, the applicant discovered that due to production or assembly errors, light leakage occurs at the edges of the screen, resulting in abnormal brightness at the edges. Even with a reflective layer, this cannot be completely avoided. The applicant proposes to include a shielding layer on the reflective strip to prevent light from escaping the light guide plate. The width of the shielding layer is greater than 1.0 mm and less than 12.0 mm.

[0051] Figure 4In the middle, the masking layer consists of the first and second black silkscreens, and the third white silkscreen is a reflective strip.

[0052] By setting a shielding layer around the screen where the light source is located, the leakage of the light source is greatly reduced or avoided, thus preventing abnormal brightness around the screen.

[0053] Figure 5 This is a schematic diagram of Example 3; as shown in the figure, it includes the first white silkscreen, which is a reflective layer.

[0054] like Figure 5 The middle layer includes a second black silkscreen, which serves as a masking layer.

[0055] like Figure 5 The process includes the third and fourth white silkscreen printing layers, which form an aesthetic layer. The width of this aesthetic layer is greater than 1.0 mm and less than 12.0 mm. This aesthetic layer allows for changes to the surrounding color, adapting to the aesthetic requirements of the product design.

[0056] The aforementioned shielding layer is black. Black silkscreen printing absorbs photons, preventing light transmission, reflection, or scattering, and effectively reducing ineffective light emission from the edges.

[0057] Figure 6 This is a schematic diagram of Example 4; as shown, it includes the first white silkscreen printing, with light red representing white in the diagram. The first white silkscreen printing is a reflective layer. Figure 6 In the middle, there is a second black silkscreen layer, which serves as a masking layer. For example... Figure 6 The middle section includes the 3rd and 4th red silkscreen layers, which are aesthetic layers. The 3rd and 4th red silkscreen layers can also be blue layers.

[0058] The aesthetic layer is printed in red silkscreen. White, red, and blue are common background colors for electronic paper, which effectively reduces the impact of surrounding elements on the overall appearance.

[0059] The aesthetic layer consists of two silkscreen printing layers. Increasing the thickness of the aesthetic layer not only improves the weather resistance of the color but also reduces light transmission, decreases the thickness of the masking layer, and can even eliminate the need for the masking layer.

[0060] like Figure 7 This is a top view of Embodiment 5. Figure 7 The black dots in the center represent the dot matrix of the light guide layer, surrounded by a masking layer. In cases where no aesthetic layer is present, the screen has a black outer ring. During the assembly process of electronic products, this black outer ring can be concealed by a casing. For example... Figure 8 The top view of Example 6 shows the white area as the screen display area and the surrounding blue aesthetic layer.

[0061] In this application, the electronic paper display module has a front-lit product structure: a CG cover plate + an LGP light guide plate + an EPD display module; the CG cover plate supports and protects the inner structure; the LGP light guide plate guides light to enable screen illumination; and the EPD display module is the display component. Light emission uniformity and brightness are crucial performance indicators for front-lit products, directly impacting user experience. Therefore, a uniformity of 80% is required, with even higher requirements reaching 90%. Simply increasing the dot matrix of the light guide plate is insufficient to meet these requirements. The product structure needs to be designed to mitigate light loss.

[0062] Typically, cover plates are screen-printed black to prevent light transmission and ensure the screen printing color is pure. Due to the light-absorbing properties of black, light scattered by the dots in the area covered by the cover plate on the light guide plate is absorbed, failing to meet brightness and uniformity requirements. This application addresses this by screen-printing white on the cover plate surface. Utilizing the reflective properties of white, the light scattered by the dots in the covered area is reflected back into the light guide plate. Figure 9 The optical data before the screen printing change were: average brightness 12.49, uniformity 84.24%; (e.g., ...) Figure 10 After the optical data was modified, the average brightness was 14.01 and the uniformity was 88.73%. The brightness and uniformity of the application have been improved, and are close to the high standard target of 90%.

[0063] As shown in the accompanying drawings, the above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of the application specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An electronic paper display module, Its features are, Includes: EPD display module, light guide plate, light source, and reflective strip; The light guide plate is located above the EPD display module; The light source is disposed on the side of the light guide plate; The reflective strip is located above the light guide plate, corresponding to the edge of the light guide plate, and is used to reflect the light emitted by the light source into the interior of the light guide plate. The width of the reflective strip is greater than 1.0 mm and less than 10.0 mm.

2. The electronic paper display module according to claim 1, characterized in that, The reflective strip is printed on the edge of the light guide plate on the upper layer of the light guide plate by screen printing, and is used to reflect light into the interior of the light guide plate; the reflective strip is composed of one, two or more layers of screen printing.

3. The electronic paper display module according to claim 1, characterized in that, Also includes cover plate The cover plate is on top of the light guide plate, and the reflective strip is printed on the edge of the cover plate to reflect light into the interior of the light guide plate.

4. The electronic paper display module according to any one of claims 1 to 3, characterized in that, The reflective strip is not black.

5. The electronic paper display module according to any one of claims 2 or 3, characterized in that, It also includes a shielding layer on the reflective strip to prevent light from escaping the light guide plate. The width of the shielding layer is greater than 1.0 mm and less than 12.0 mm.

6. The electronic paper display module according to claim 5, characterized in that, It also includes an aesthetic layer on the masking layer, the aesthetic layer having a width greater than 1.0 mm and less than 12.0 mm.

7. The electronic paper display module according to claim 5, characterized in that, The masking layer is black.

8. The electronic paper display module according to claim 6, characterized in that, The aesthetic layer is silkscreened in white, red, or blue.

9. The electronic paper display module according to claim 6, characterized in that, The aesthetic layer consists of one, two, or more layers of screen printing.

10. A device with an electronic paper display screen, characterized in that, Includes the electronic paper display module according to any one of claims 1 to 9.

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