TWI870999B - Front light module and electrophoretic display device - Google Patents

Abstract

A front light module including a light guide plate, a light source, a protective cover plate, an appearance color layer, and a functional layer is provided. The light guide plate has a first surface, a second surface opposite to the first surface, and a light incident surface connecting the first surface with the second surface. The light source is disposed beside the light incident surface and configured to emit light towards the light incident surface. The protective cover plate is disposed on the first surface, and has a third surface facing away from the light guide plate and a fourth surface facing the light guide plate. The appearance color layer is disposed on a part of the third surface. The functional layer covers the appearance color layer and the third surface. An electrophoretic display device is also provided.

Description

Front light module and electrophoretic display device

The present invention relates to a light source module and a display device, and in particular to a front light module and an electrophoretic display device.

The front light module can be applied to a reflective display device (such as an electrophoretic display device) to provide illumination for the reflective display panel, so that the user can still use the reflective display device normally even in a low-light environment.

Generally speaking, the front light module includes a light source, a light guide plate and a protective cover. The light guide plate can guide the illumination light emitted by the light source to the reflective display panel (such as an electrophoretic display panel) below the front light module. The reflective display panel reflects the illumination light into image light, and then the image light penetrates the light guide plate and the protective cover and is transmitted to the user's eyes, so that the user can see the display screen of the electrophoretic display panel.

For aesthetic reasons, the surrounding area of the protective cover is usually coated with an ink layer to shield the components below, leaving only the display area without ink. Generally speaking, the ink is applied to the lower surface of the protective cover, that is, the surface of the protective cover facing the light guide plate, and then the protective cover can be attached to the light guide plate through an optical adhesive layer. However, under such a design, since the protective cover has a certain thickness, part of the light from the light guide plate will be incident on the upper surface of the protective cover obliquely and leave the display area for a short distance in the horizontal direction. Then, the oblique light is reflected or totally reflected by the upper surface of the protective cover to the ink layer on the lower surface of the protective cover. At this time, the ink layer reflects the light to the upper surface of the protective cover, and then the light penetrates the upper surface and is transmitted to the user's eyes, causing a halo phenomenon around the display area. This situation is more serious when using non-black ink.

The present invention provides a front light module which can effectively suppress the halo phenomenon.

The present invention provides an electrophoretic display device, which can effectively suppress the halo phenomenon around the display area.

An embodiment of the present invention provides a front light module, including a light guide plate, a light source, a protective cover plate, an appearance color layer and a functional layer. The light guide plate has a first surface, a second surface opposite to the first surface and a light incident surface connecting the first surface and the second surface. The light source is arranged beside the light incident surface and is used to emit light toward the light incident surface. The protective cover plate is arranged on the first surface, and the protective cover plate has a third surface facing away from the light guide plate and a fourth surface facing the light guide plate. The appearance color layer is arranged on a portion of the third surface. The functional layer covers the appearance color layer and the third surface.

An embodiment of the present invention provides an electrophoretic display device, comprising the above-mentioned front light module and an electrophoretic display panel. The electrophoretic display panel is disposed below the front light module, wherein the light guide plate is located between the electrophoretic display panel and the protective cover.

In the front light module and the electrophoretic display device of the embodiment of the present invention, the appearance color layer is arranged on the third surface of the protective cover plate facing away from the light guide plate, and the functional layer covers the appearance color layer. Since the appearance color layer is arranged on the upper surface of the protective cover plate, the halo phenomenon formed by the reflection of the appearance color layer can be effectively suppressed.

FIG1A is a cross-sectional schematic diagram of an electrophoretic display device of an embodiment of the present invention, and FIG1B is a front view schematic diagram of the electrophoretic display device of FIG1A , wherein FIG1A is a cross-sectional schematic diagram cut along the I-I line of FIG1B . Referring to FIG1A and FIG1B , the electrophoretic display device 100 of the present embodiment includes a front light module 200 and an electrophoretic display panel 110, wherein the electrophoretic display panel 110 is disposed below the front light module 200. The front light module 200 includes a light guide plate 210, a light source 220, a protective cover plate 230, an appearance color layer 240, and a functional layer 250. The light guide plate 210 has a first surface 212, a second surface 214 opposite to the first surface 212, and a light incident surface 216 connecting the first surface 212 and the second surface 214. The light source 220 is disposed beside the light incident surface 216 and is used to emit light toward the light incident surface 216. In this embodiment, the light source 220 is, for example, a light emitting diode, a cold cathode fluorescent lamp, or other appropriate light emitting element. The illumination light beam 222 emitted by the light source 220 enters the light guide plate 210 from the light incident surface 216 and is totally reflected by the first surface 212 and the second surface 214 to be transmitted in the light guide plate 210. In addition, an optical microstructure 218 is disposed on at least one of the first surface 212 and the second surface 214 (in FIG. 1A , the optical microstructure 218 is disposed on the second surface 214 as an example). When the illumination light beam 222 is irradiated on the optical microstructure 218, the optical microstructure 218 will destroy the above-mentioned total reflection phenomenon, so that a portion of the illumination light beam 222 is scattered downward to the electrophoretic display panel 110, and another portion of the illumination light beam 222 is scattered upward to leave the light guide plate 210. The electrophoretic display panel 110 has a pixel structure that can form different reflection patterns. Therefore, the electrophoretic display panel 110 will reflect the illumination light beam 222 scattered downward and convert it into an image light beam 112, and the image light beam 112 then sequentially penetrates the light guide plate 210 and the protective cover 230 and is transmitted to the user's eyes. In this way, even if the brightness of the ambient light is not sufficient, the user can still view the image displayed by the electrophoretic display panel 110 .

In this embodiment, the light guide plate 210 is located between the electrophoretic display panel 110 and the protective cover plate 250. The protective cover plate 230 is disposed on the first surface 212, and the protective cover plate 230 has a third surface 232 facing away from the light guide plate 210 and a fourth surface 234 facing the light guide plate 210. The appearance color layer 240 is disposed on a portion of the third surface 232. The functional layer 250 covers the appearance color layer 240 and the third surface 232. In this embodiment, the appearance color layer 240 is, for example, an ink layer, which can be formed by printing the ink layer on a portion of the third surface 232 by inkjet printing. In one embodiment, the appearance color layer 240 is directly formed on the third surface 232 by inkjet printing. In other embodiments, the ink layer may be formed on a portion of the third surface 232 by printing or transfer.

In this embodiment, the appearance color layer 240 is disposed in the peripheral area of the third surface 232, that is, the appearance color layer 240 forms the effect of the border area as shown in FIG. 1B , and the appearance color layer 240 covers the light source 220, and the appearance color layer 240 exposes the display area 111 of the electrophoretic display panel 110. In this embodiment, the appearance color layer 240 includes a plurality of stacked sub-ink layers. For example, these sub-ink layers include a non-black sub-ink layer 244 and a black sub-ink layer 242, wherein the black sub-ink layer 242 is disposed between the protective cover 230 and the non-black sub-ink layer 244. The non-black sub-ink layer 244 is, for example, a white sub-ink layer or a sub-ink layer of other colors, which can form the appearance color of the frame area, such as white or other colors. In addition, the black sub-ink layer 242 below the non-black sub-ink layer 244 can absorb stray light to prevent stray light from leaking out of the frame area. In another embodiment, the appearance color layer 240 can also be a single ink layer.

In this embodiment, the functional layer 250 is an antiglare layer. However, in other embodiments, the functional layer 250 may also be an anti-fingerprint layer, an anti-reflection layer or a hard coating layer. The functional layer 250 may be formed on the appearance color layer 240 and the third surface 232 by ultraviolet imprinting (UV imprinting). However, in other embodiments, the functional layer 250 may also be formed on the appearance color layer 240 and the third surface 232 by coating, spraying, etc. Furthermore, the process of the functional layer 250 may be completed by a single process or by multiple processes.

In the present embodiment, the protective cover 230 is a transparent substrate, and the material of the protective cover 230 is, for example, plastic or glass. In addition, in one embodiment, the front light module 200 further includes a touch panel 260, which is disposed between the light guide plate 210 and the protective cover 230, so that the electrophoretic display device 100 has a touch function. However, in other embodiments, the front light module 200 may not include the touch panel 260, and the protective cover 230 is disposed on the light guide plate 210 to form an electrophoretic display device without a touch function. In another embodiment, the front light module 200 may not include the touch panel 260, and the protective cover 230 is disposed on the light guide plate 210 to form an electrophoretic display device with a touch function together with the electrophoretic display panel 110 with a built-in touch function.

In the front light module 200 and the electrophoretic display device 100 of the present embodiment, the appearance color layer 240 is disposed on the third surface 232 of the protective cover 230 facing away from the light guide plate 210, and the functional layer 250 covers the appearance color layer 240. Since the appearance color layer 240 is disposed on the upper surface of the protective cover 230, when the illumination light beam 222 obliquely impinges on the inner edge of the appearance color layer 240 of the protective cover 230, the obliquely incident illumination light beam 222 is transmitted in the thin thickness of the functional layer 250 and is reflected by the upper surface of the functional layer 250 to the upper surface of the appearance color layer 240. At this time, even if the appearance color layer 240 reflects the illumination beam 222 to the user's eyes, the thickness of the functional layer 250 is very thin, resulting in the reflection position being very close to the inner edge of the appearance color layer 240, so the user can hardly feel the existence of halo. In contrast, in the prior art, the ink layer is made on the lower surface of the protective cover plate. Since the oblique incident light passes through the thick thickness of the protective cover plate, the position where it is reflected by the ink layer is far away from the inner edge of the ink layer, which will cause the halo to be clearly visible. Therefore, compared with the prior art, the front light module 200 and the electrophoretic display device 100 of this embodiment can effectively suppress the halo phenomenon caused by the reflection of the appearance color layer 240. In this embodiment, the thickness of the functional layer 250 is smaller than the thickness of the protective cover 230 , for example, much smaller than the thickness of the protective cover 230 .

FIG2 is a cross-sectional schematic diagram of an electrophoretic display device of another embodiment of the present invention. Referring to FIG2 , the electrophoretic display device 100a of this embodiment is similar to the electrophoretic display device 100 of FIG1A , and the difference between the two is as follows. In the electrophoretic display device 100 of this embodiment, the appearance color layer 240a is a single-layer film, such as a black ink layer, which is suitable for the case where the border area needs to be black.

FIG3 is a cross-sectional schematic diagram of an electrophoretic display device of another embodiment of the present invention. Referring to FIG3 , the electrophoretic display device 100 b of the present embodiment is similar to the electrophoretic display device 100 of FIG1A , and the main differences between the two are described as follows. In the electrophoretic display device 100 b of the present embodiment, the front light module 200 b further includes a transparent layer 270 disposed between the non-black sub-ink layer 244 and the black sub-ink layer 242. In the present embodiment, the refractive index of the transparent layer 270 is greater than the refractive index of the protective cover 230 and greater than the refractive index of the functional layer 250. In addition, in the present embodiment, the transparent layer 270 covers the side of the inner edge 241 of the black sub-ink layer 242.

When the front light module 200b does not have the transparent layer 270, if the ink printing positions of the non-black sub-ink layer 244 and the black sub-ink layer 242 are offset and inaccurate, when the illumination light beam 222 irradiates the inner edge of the non-black sub-ink layer 244, it is easy for the user to see a bright line at this position. In contrast, in the present embodiment, when the illumination light beam 222b irradiates the position near the inner edge of the non-black sub-ink layer 244, it will first pass through the transparent layer 270, and the transparent layer 270 has a higher refractive index. Therefore, the illumination light beam 222b will continuously undergo total reflection on the upper and lower surfaces of the transparent layer 270, and will be confined in the transparent layer 270 and transmitted in the transparent layer 270, and finally emitted from the side of the outer edge of the transparent layer 270, and will not be seen by the user's eyes. In this way, the transparent layer 270 can effectively reduce the light transmission energy of the non-black sub-ink layer 244. Even if the ink printing positions of the non-black sub-ink layer 244 and the black sub-ink layer 242 are slightly offset, the problem of the user seeing the bright line will not or will not easily occur.

FIG4 is a cross-sectional schematic diagram of an electrophoretic display device of another embodiment of the present invention. Referring to FIG4 , the electrophoretic display device 100c of this embodiment is similar to the electrophoretic display device 100b of FIG3 , and the main differences between the two are as follows. In the front light module 200c of the electrophoretic display device 100c of this embodiment, the transparent layer 270c covers the black sub-ink layer 242 and the portion of the third surface 232 that is not covered by the appearance color layer 240. In other words, the transparent layer 270c can also be configured on the protective cover 230 in its entirety, and it can be penetrated by the image light beam 112 without affecting the display function of the electrophoretic display device 200c. The transparent layer 270c has a similar function to the transparent layer 270 in FIG. 3 , and can also allow the illumination light beam 222b to be emitted from the side of the outer edge of the transparent layer 270c to effectively reduce the light transmission energy of the non-black sub-ink layer 244, thereby effectively improving the above-mentioned bright line problem.

In summary, in the front light module and the electrophoretic display device of the embodiment of the present invention, the appearance color layer is disposed on the third surface of the protective cover plate facing away from the light guide plate, and the functional layer covers the appearance color layer. Since the appearance color layer is disposed on the upper surface of the protective cover plate, the halo phenomenon formed by the reflection of the appearance color layer can be effectively suppressed.

100, 100a, 100b, 100c: electrophoretic display device 110: electrophoretic display panel 111: display area 112: image beam 200, 200b, 200c: front light module 210: light guide plate 212: first surface 214: second surface 216: light incident surface 218: optical microstructure 220: light source 222, 222b: illumination beam 230: protective cover 232: third surface 234: fourth surface 240, 240a: appearance color layer 241: inner edge 242: black sub-ink layer 244: non-black sub-ink layer 250: functional layer 260: touch panel 270, 270c: transparent layer

FIG. 1A is a schematic cross-sectional view of an electrophoretic display device of an embodiment of the present invention. FIG. 1B is a schematic front view of the electrophoretic display device of FIG. 1A. FIG. 2 is a schematic cross-sectional view of an electrophoretic display device of another embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of an electrophoretic display device of yet another embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of an electrophoretic display device of yet another embodiment of the present invention.

100: Electrophoresis display device

110: Electrophoretic display panel

112: Image beam

200: Front light module

210: Light guide plate

212: First surface

214: Second surface

216: Light-entering surface

218:Optical microstructures

220: Light source

222: Lighting beam

230: Protective cover

232: Third surface

234: The fourth surface

240: Appearance color layer

242: Black sub-ink layer

244: Non-black sub-ink layer

250: Functional layer

260: Touch panel

Claims (22)

A front light module includes: a light guide plate having a first surface, a second surface opposite to the first surface, and a light incident surface connecting the first surface and the second surface; a light source arranged beside the light incident surface and used to emit light toward the light incident surface; a protective cover plate arranged on the first surface, the protective cover plate having a third surface facing away from the light guide plate and a fourth surface facing the light guide plate; an appearance color layer arranged on a portion of the third surface, wherein the appearance color layer includes a plurality of stacked sub-ink layers; and a functional layer covering the appearance color layer and the third surface. The front light module as described in claim 1, wherein the functional layer is an anti-glare layer, an anti-fingerprint layer, an anti-reflection layer or a hard coat layer. The front light module as described in claim 1, wherein the appearance color layer is arranged in the peripheral area of the third surface. The front light module as described in claim 1, wherein the sub-ink layers include: a non-black sub-ink layer; and a black sub-ink layer, disposed between the protective cover and the non-black sub-ink layer. The front light module as described in claim 4 further includes a transparent layer disposed between the non-black sub-ink layer and the black sub-ink layer. The front light module as described in claim 5, wherein the refractive index of the transparent layer is greater than the refractive index of the protective cover plate and greater than the refractive index of the functional layer. A front light module as described in claim 5, wherein the transparent layer covers the side of the inner edge of the black sub-ink layer. A front light module as described in claim 5, wherein the transparent layer covers the black sub-ink layer and another portion of the third surface not covered by the appearance color layer. The front light module as described in claim 1, wherein the protective cover is a transparent substrate. The front light module as described in claim 1, wherein the material of the protective cover is plastic or glass. The front light module as described in claim 1, wherein the appearance color layer is directly formed on the third surface by inkjet printing. An electrophoretic display device includes: a front light module, including: a light guide plate having a first surface, a second surface opposite to the first surface, and a light incident surface connecting the first surface and the second surface; a light source arranged beside the light incident surface and used to emit light toward the light incident surface; a protective cover plate arranged on the first surface, the protective cover plate having a third surface facing away from the light guide plate and a fourth surface facing the light guide plate; an appearance color layer arranged on a portion of the third surface, wherein the appearance color layer includes a plurality of stacked sub-ink layers; and a functional layer covering the appearance color layer and the third surface; and an electrophoretic display panel arranged below the front light module, wherein the light guide plate is located between the electrophoretic display panel and the protective cover plate. An electrophoretic display device as described in claim 12, wherein the functional layer is an anti-glare layer, an anti-fingerprint layer, an anti-reflective layer or a hard coat layer. An electrophoretic display device as described in claim 12, wherein the appearance color layer is arranged in the peripheral area of the third surface. An electrophoretic display device as described in claim 12, wherein the sub-ink layers include: a non-black sub-ink layer; and a black sub-ink layer, disposed between the protective cover and the non-black sub-ink layer. The electrophoretic display device as described in claim 15, wherein the front light module further includes a transparent layer disposed between the non-black sub-ink layer and the black sub-ink layer. An electrophoretic display device as described in claim 16, wherein the refractive index of the transparent layer is greater than the refractive index of the protective cover plate and greater than the refractive index of the functional layer. An electrophoretic display device as described in claim 16, wherein the transparent layer covers the side of the inner edge of the black sub-ink layer. An electrophoretic display device as described in claim 16, wherein the transparent layer covers the black sub-ink layer and another portion of the third surface not covered by the appearance color layer. An electrophoretic display device as described in claim 12, wherein the protective cover is a transparent substrate. An electrophoretic display device as described in claim 12, wherein the material of the protective cover is plastic or glass. The electrophoretic display device as described in claim 12, wherein the front light module further includes a touch panel disposed between the light guide plate and the protective cover.

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