CN217112989U - Front light module and display device - Google Patents

Abstract

A front light module includes a light guide plate and a light source. The light guide plate is provided with a light incident surface, a light emergent surface and a bottom surface, wherein the light emergent surface and the bottom surface are connected with the light incident surface and are opposite to each other. The light-emitting surface of the light guide plate is provided with a plurality of micro-groove structures which are recessed into the light-emitting surface. The orthographic projection outline of each micro-groove structure on a plane vertical to the light incident surface and the light emergent surface is trapezoidal. The light source is arranged on one side of the light incident surface of the light guide plate. Each of the micro-groove structures has a light-facing surface, a light-backing surface and a groove bottom surface connecting the light-facing surface and the light-backing surface. The light receiving surface is positioned between the light incident surface and the backlight surface. The bottom surface of the groove is parallel to the extending plane of the light-emitting surface. A first included angle is formed between the light facing surface and the extension plane, and the first included angle ranges from 30 degrees to 38 degrees. A display device adopting the front light module is provided. The utility model discloses a stray light that preceding optical module generated is less for the light yield of illumination is more, the utility model discloses a display device has the demonstration contrast of preferred.

Description

Front light module and display device

technical field

The utility model relates to an optical module and an electronic device, in particular to a front light module and a display device.

Background technique

The reflective display panel uses ambient light as a light source to illuminate the display panel to form display light, and then reflects the display light to the user's eyes. Compared with the transmissive display panel or the self-luminous display panel, the reflective display panel has the advantages of low thickness, power saving, high contrast in strong light environment, and reduced visual fatigue of users.

However, when the ambient light is insufficient, a front light source needs to be provided on the display side of the reflective display panel to provide illumination. However, part of the light beam from the front light source does not irradiate the reflective display panel and emits light directly to form stray light, causing the user to receive stray light and display light at the same time, further generating glare and reducing the contrast of the display screen and affecting viewing quality.

Utility model content

The utility model provides a front light module, which generates less stray light and has more light for lighting.

The utility model provides a display device which has better display contrast.

Other purposes and advantages of the utility model can be further understood from the technical characteristics disclosed in the utility model.

In order to achieve one or part or all of the above objectives or other objectives, an embodiment of the present invention provides a front light module. The front light module includes a light guide plate and a light source. The light guide plate has a light incident surface, a light exit surface and a bottom surface, the light exit surface and the bottom surface are connected to the light incident surface and are opposite to each other. The light-emitting surface of the light guide plate is provided with a plurality of micro-groove structures recessed into the light-emitting surface. The orthographic profile of each of the micro-groove structures on a plane perpendicular to the light-incident surface and the light-exit surface is trapezoidal. The light source is arranged on one side of the light incident surface of the light guide plate. Each of these micro-groove structures has a light-facing surface, a back-light surface and a groove bottom connecting the light-facing surface and the backlight surface. The light receiving surface is located between the light incident surface and the backlight surface. The bottom surface of the groove is parallel to the extension plane where the light-emitting surface is located. There is a first included angle between the light-receiving surface and the extending plane, and the first included angle ranges from 30 degrees to 38 degrees.

In order to achieve one or part or all of the above objectives or other objectives, an embodiment of the present invention provides a display device. The display device includes a light guide plate, a light source and a reflective display panel. The light guide plate has a light incident surface, a light exit surface and a bottom surface, the light exit surface and the bottom surface are connected to the light incident surface and are opposite to each other. The light-emitting surface of the light guide plate is provided with a plurality of micro-groove structures recessed into the light-emitting surface. The orthographic profile of each of these micro-groove structures on a plane perpendicular to the light-incident surface and the light-exit surface is trapezoidal. The light source is arranged on one side of the light incident surface of the light guide plate. The reflective display panel is arranged on one side of the bottom surface of the light guide plate. Each of these micro-groove structures has a light-facing surface, a back-light surface and a groove bottom connecting the light-facing surface and the backlight surface. The light receiving surface is located between the light incident surface and the backlight surface. The bottom surface of the groove is parallel to the extension plane where the light-emitting surface is located. There is a first included angle between the light-receiving surface and the extending plane, and the first included angle ranges from 30 degrees to 38 degrees.

Based on the above, in the display device according to an embodiment of the present invention, a plurality of micro-groove structures are provided on the light emitting surface of the light guide plate of the front light module. Each micro-groove structure has a light-receiving surface facing the light source. By designing the included angle between the light-receiving surface and the extended plane of the light-emitting surface in the range of 30 degrees to 38 degrees, the generation of stray light can be effectively suppressed, and at the same time, the amount of illumination light used to illuminate the reflective display panel can be increased. It helps to improve the display contrast of the display device.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail with accompanying drawings.

Description of drawings

FIG. 1 is a schematic cross-sectional view of a display device according to a first embodiment of the present invention.

FIG. 2 is a schematic top view of the front light module in FIG. 1 .

FIG. 3 is a graph showing the relationship between the light output contrast and the first included angle of the light guide plate in FIG. 1 .

FIG. 4 is a graph showing the relationship between the light output contrast of the light guide plate in FIG. 1 and the second included angle.

FIG. 5 is a graph showing the relationship between light output and relative depth of the light guide plate in FIG. 1 .

6 is a schematic cross-sectional view of a display device according to a second embodiment of the present invention.

FIG. 7 is a schematic bottom view of the front light module of FIG. 6 .

List of reference signs

10, 10A: display device

100, 100A: front optical module

110, 110A: light guide plate

110bs: Bottom

110es: light emitting surface

110is: incident surface

115, 115A: micro groove structure

115b: groove bottom surface

115r, 115r”: facing the light

115s, 115s”: backlit surface

120: light source

200: reflective display panel

250: Polarizer

A1: The first included angle

A2: Second included angle

CL1: the first arc line

CL2: the second arc line

d: depth

DS: display surface

EB: ambient light

LB1: First Beam

LB2: second beam

P1: Extended plane

R: radius of curvature

SL1, SL2: Straight line

X, Y, Z: directions.

Detailed ways

The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or back, etc., are only referring to the directions of the drawings. Accordingly, the directional terms used are for illustration and not for limitation of the invention.

FIG. 1 is a schematic cross-sectional view of a display device according to a first embodiment of the present invention. FIG. 2 is a schematic top view of the front light module in FIG. 1 . FIG. 3 is a graph showing the relationship between the light output contrast and the first included angle of the light guide plate in FIG. 1 . FIG. 4 is a graph showing the relationship between the light output contrast of the light guide plate in FIG. 1 and the second included angle. FIG. 5 is a graph showing the relationship between light output and relative depth of the light guide plate in FIG. 1 .

Referring to FIG. 1 and FIG. 2 , the display device 10 includes a light guide plate 110 , a light source 120 and a reflective display panel 200 . The light guide plate 110 and the light source 120 are disposed on one side of the display surface DS of the reflective display panel 200 . The display device 10 is used to utilize ambient light as an illumination source for the reflective display panel 200 . When the ambient light is insufficient, the front light module 100 formed by the light guide plate 110 and the light source 120 can provide the reflective display panel 200 with illumination light required for display.

In this embodiment, the reflective display panel 200 is, for example, a reflective liquid crystal display panel. Therefore, the display device 10 may also optionally include a polarizer 250 disposed between the reflective display panel 200 and the front light module 100 , further speaking, the polarizer 250 is disposed between the light guide plate 110 and the reflective display panel 200 . However, the present invention is not limited thereto. According to other embodiments, the reflective display panel 200 may also be an Electrophoretic Display (EPD) panel or an Electrowetting Display (EWD) panel, so the display device formed by it does not need to be configured with the polarizer 250 .

In detail, the light guide plate 110 has a light incident surface 110is, a light exit surface 110es and a bottom surface 110bs, the light exit surface 110es and the bottom surface 110bs are connected to the light incident surface 110is and are opposite to each other. The material of the light guide plate 110 includes, for example, thermoplastic polymers such as polymethacrylate (PMMA), cycloolefin (COC) or polycarbonate (PC), but is not limited thereto. It is particularly noted that a plurality of micro-groove structures 115 are disposed on the light-emitting surface 110es of the light guide plate 110 . The micro-groove structures 115 can be arranged in multiple rows on the light-emitting surface 110es along a direction parallel to the light-incident surface 110is (for example, the direction Y), and are spaced apart from each other. In this embodiment, the micro-groove structures 115 can be arranged in a dislocation along the direction X, but it is not limited thereto.

The orthographic profile of each micro-groove structure 115 on a plane perpendicular to the light-incident surface 110is and the light-exit surface 110es is trapezoidal and concave into the light-exit surface 110es. Each micro-groove structure 115 has a light-receiving surface 115r, a backlight surface 115s, and a groove bottom 115b connecting the light-receiving surface 115r and the backlight surface 115s, wherein the light-receiving surface 115r is located between the light incident surface 110is and the backlight surface 115s.

The light source 120 is disposed on one side of the light incident surface 110is of the light guide plate 110, and may be a combination of a plurality of light emitting diodes (Light Emitting Diode, LED). The light emitting diode is, for example, a submillimeter light emitting diode (mini LED) or a micro light emitting diode (micro LED). Since the light source 120 of the present invention is used to provide or supplement the illumination light required when the ambient light is weak, the light source 120 is preferably a white light source, which can be directly formed by using white light emitting diodes, or by using wavelength conversion The material converts the light emitted by a non-white light-emitting diode (such as blue or ultraviolet light) into colored light (such as red, green or blue light) that can be mixed into white light.

The reflective display panel 200 is disposed on one side of the bottom surface 110bs of the light guide plate 110 , and is used to reflect the ambient light EB or the light beam (such as the second light beam LB2 ) emitted by the light source 120 to achieve the effect of displaying images.

For example, the first light beam LB1 from the light source 120 does not exit through the bottom surface 110bs of the light guide plate 110 and is reflected by the reflective display panel 200 after passing through the light guide plate 110, but passes through the light-receiving surface of the micro-groove structure 115 115r emerges and forms stray light without display information. Differently, after the second light beam LB2 from the light source 120 is transmitted in the light guide plate 110, after being reflected by the light-receiving surface 115r of the micro-groove structure 115, it emerges from the bottom surface 110bs of the light guide plate 110, and passes through the polarizer 250 and reflects The reflection of the type display panel 200 forms the second light beam LB2 with display information.

In particular, the first light beam LB1 and the second light beam LB2 here can be two light beams entering the micro-groove structure 115 at different angles, or they can be the same light beam passing through the light-receiving surface of the micro-groove structure 115 Two different sub-beams produced by partial refraction and partial reflection of 115r.

In this embodiment, the groove bottom surface 115b is parallel to the light-emitting surface 110es and the extension plane P1 where the light-emitting surface 110es is located, and the light-receiving surface 115r is inclined to the light-emitting surface 110es and the groove bottom surface 115b. More specifically, there is a first included angle A1 between the light-receiving surface 115r and the extension plane P1 where the light-emitting surface 110es is located, and the first included angle A1 is within a range of 30 degrees to 38 degrees. Accordingly, the generation of stray light (such as the first light beam LB1 ) can be significantly reduced, and at the same time, the output of the illumination light (such as the second light beam LB2 ) can be increased. Therefore, better display contrast can be provided for the display device 10 .

On the other hand, there is a second included angle A2 between the backlight surface 115s of the micro-groove structure 115 and the extension plane P1 where the light-emitting surface 110es is located, and the second included angle A2 can preferably range from 60 degrees to 90 degrees. . The bottom surface of the groove 115b and the light-emitting surface 110es have a depth d along the normal direction (eg, direction Z) of the light-emitting surface 110es, and the depth d is preferably less than or equal to 3.5 microns.

In this embodiment, the optical performance of the light guide plate 110 can be measured according to an index, such as: the aforementioned light contrast defined by the ratio of the total light output of illumination light and stray light to the total light output of stray light. When the stray light generated by the light guide plate is less, or even more illumination light is generated, the light contrast will be greater; otherwise, the light contrast will be smaller.

For example, the light contrast of the light guide plate 110 decreases as the first included angle A1 (ie, the light angle) of the light-receiving surface 115r increases (as shown in FIG. 3 ). Conversely, the light contrast of the light guide plate 110 increases as the second included angle A2 (ie, the backlight angle) of the backlight surface 115s increases (as shown in FIG. 4 ). From another point of view, the light contrast of the light guide plate 110 increases as the depth d of the micro-groove structure 115 decreases (as shown in FIG. 5 ).

In particular, although the light contrast in FIG. 3 decreases with the increase of the first included angle A1, by synchronously increasing the second included angle A2 of the backlight surface 115s, even if the first included angle of the light-receiving surface 115r is increased, The angle A1 can also maintain the light output contrast of the light guide plate 110 within an ideal numerical range. For example, in a preferred embodiment, when the second included angle A2 of the backlight surface 115s is 60 degrees, and the first included angle A1 of the light-receiving surface 115r is in the range of 34 degrees to 36 degrees, The light output contrast of the light guide plate 110 can be maintained in a range above 4.62 (shown by the dotted line in FIG. 3 ). When the first included angle A1 of the light-receiving surface 115r is to be increased to 37 degrees or 38 degrees, the ideal light contrast can be maintained by increasing the second included angle A2 of the backlight surface 115s to 70 degrees or more than 80 degrees. .

On the other hand, since the reflective display panel 200 has the effect of diffusing light, when the first included angle A1 of the light-receiving surface 115r of the micro-groove structure 115 is designed in the range of 34 degrees to 36 degrees, most lighting After being reflected by the reflective display panel 200 , the light (such as the second light beam LB2 ) will deviate toward the normal viewing angle. Therefore, the forward light output of the display device 10 can also be increased. For example, the front light module 100 here has a higher amount of forward light output when the reflective display panel 200 is provided than when the reflective display panel 200 is not provided, and thus can be used for the display device 10 Provides better display contrast, but is not limited to.

Another embodiment will be listed below to illustrate the present disclosure in detail, wherein the same components will be marked with the same symbols, and the description of the same technical content will be omitted.

6 is a schematic cross-sectional view of a display device according to a second embodiment of the present invention. FIG. 7 is a schematic bottom view of the front light module of FIG. 6 . Please refer to FIG. 6 and FIG. 7 , the difference between the display device 10A of this embodiment and the display device 10 of FIG. 1 lies in that the configuration of the micro-groove structure is different. Specifically, in the display device 10A of this embodiment, the light-receiving surface 115r" and the backlight surface 115s" of the micro-groove structure 115A on the light guide plate 110A of the front light module 100A are both circular arc surfaces.

The orthographic profile of each micro-groove structure 115A on the bottom surface 110bs of the light guide plate 110A is a shape surrounded by the first arc line CL1 , the second arc line CL2 and two straight lines SL1 and SL2 . Wherein, the two straight lines SL1 and SL2 are, for example, parallel to each other, and the first arc line CL1 and the second arc line CL2 are convex toward the light source 120 and have a curvature radius R. For example, the radius of curvature R may be greater than or equal to 10 microns. Preferably, the radius of curvature R may be greater than or equal to 25 microns. However, the present invention is not limited thereto. According to other embodiments, the curvature radii of the first arc line CL1 and the second arc line CL2 may also be different from each other.

Since the profiles of the light-receiving surface 115r" and the backlight surface 115s" of the micro-groove structure 115A of the present embodiment are similar to the micro-groove structure 115 of FIG. The design ranges of the first included angle of the light surface 115r" relative to the extending plane P1 of the light emitting surface 110es and the second included angle of the backlight surface 115s" relative to the extending plane P1 of the light emitting surface 110es are similar to the display device 10 of FIG. 1 . Therefore, for other descriptions about the micro-groove structure 115A, please refer to the relevant paragraphs of the above-mentioned embodiments, which will not be repeated here.

To sum up, in the display device according to an embodiment of the present invention, a plurality of micro-groove structures are provided on the light emitting surface of the light guide plate of the front light module. Each micro-groove structure has a light-receiving surface facing the light source. By designing the included angle between the light-receiving surface and the extended plane of the light-emitting surface in the range of 30 degrees to 38 degrees, the generation of stray light can be effectively suppressed, and at the same time, the amount of illumination light used to illuminate the reflective display panel can be increased. It helps to improve the display contrast of the display device.

The above is only a preferred embodiment of the utility model, and cannot limit the implementation scope of the utility model, that is, all simple equivalent changes and modifications made according to the claims of the utility model and the content of the description are still within the scope of the utility model. Within the scope covered by the utility model patent. In addition, any embodiment or claim of the utility model does not need to achieve all the objects or advantages or features disclosed in the utility model. In addition, the abstract of the description and the name of the utility model are only used to assist in the retrieval of patent documents, and are not used to limit the scope of rights of the utility model. In addition, terms such as "first" and "second" mentioned in the specification or claims are only used to name elements or to distinguish different embodiments or ranges, and are not used to limit the number of elements. upper or lower limit.

Claims (13)

1. A display device comprises a light guide plate, a light source and a reflective display panel

The light guide plate is provided with a light incident surface, a light emergent surface and a bottom surface, the light emergent surface and the bottom surface are connected with the light incident surface and are opposite to each other, the light emergent surface of the light guide plate is provided with a plurality of micro-groove structures which are recessed into the light emergent surface, and the orthographic projection outline of each of the micro-groove structures on a plane vertical to the light incident surface and the light emergent surface is trapezoidal;

the light source is arranged on one side of the light incident surface of the light guide plate; and

the reflective display panel is disposed at one side of the bottom surface of the light guide plate,

each of the micro-groove structures is provided with a light facing surface, a light backing surface and a groove bottom surface connecting the light facing surface and the light backing surface, the light facing surface is located between the light incident surface and the light backing surface, the groove bottom surface is parallel to an extending plane where the light emitting surface is located, a first included angle is formed between the light facing surface and the extending plane, and the first included angle ranges from 30 degrees to 38 degrees.

2. The display device according to claim 1, wherein the backlight surface and the extension plane have a second included angle therebetween, and the second included angle is in a range from 60 degrees to 90 degrees.

3. The display device according to claim 1, wherein the first included angle is in a range of 34 degrees to 36 degrees.

4. The display device according to claim 1, wherein the groove bottom surface and the light emitting surface have a depth along a normal direction of the light emitting surface, and the depth is less than or equal to 3.5 μm.

5. The display device according to claim 1, wherein a portion of the plurality of micro-groove structures are arranged on the light emitting surface along a direction parallel to the light incident surface and spaced apart from each other.

6. The display device according to claim 1, wherein an orthographic projection profile of each of the plurality of micro-groove structures on the bottom surface is a shape surrounded by a first arc line, a second arc line and two straight lines, the first arc line protrudes outward toward the light source, the light-facing surface is an arc surface protruding outward toward the light source, and a radius of curvature of the first arc line is greater than or equal to 10 micrometers.

7. The display device according to claim 1, further comprising a polarizer,

the polaroid is arranged between the light guide plate and the reflective display panel.

8. A front light module is characterized in that the front light module comprises a light guide plate and a light source, wherein

The light guide plate is provided with a light incident surface, a light emergent surface and a bottom surface, the light emergent surface and the bottom surface are connected with the light incident surface and are opposite to each other, the light emergent surface of the light guide plate is provided with a plurality of micro-groove structures which are recessed into the light emergent surface, and the orthographic projection outline of each of the micro-groove structures on a plane vertical to the light incident surface and the light emergent surface is trapezoidal; and

the light source is arranged on one side of the light incident surface of the light guide plate, each of the micro-groove structures is provided with a light facing surface, a light reflecting surface and a groove bottom surface which is connected with the light facing surface and the light reflecting surface, the light facing surface is located between the light incident surface and the light reflecting surface, the groove bottom surface is parallel to an extending plane where the light emitting surface is located, a first included angle is formed between the light facing surface and the extending plane, and the first included angle ranges from 30 degrees to 38 degrees.

9. The front light module of claim 8, wherein the backlight surface and the extension plane have a second included angle therebetween, and the second included angle is in a range from 60 degrees to 90 degrees.

10. The front light module of claim 8, wherein the first included angle is in a range of 34 degrees to 36 degrees.

11. The front optical module as claimed in claim 8, wherein the groove bottom surface and the light emitting surface have a depth along a normal direction of the light emitting surface, and the depth is not more than 3.5 μm.

12. The front light module of claim 8, wherein a portion of the plurality of micro-groove structures are arranged on the light emitting surface along a direction parallel to the light incident surface and spaced apart from each other.

13. The front light module of claim 8, wherein an orthographic projection profile of each of the micro groove structures on the bottom surface is a shape surrounded by a first arc line, a second arc line and two straight lines, the first arc line protrudes outward toward the light source, the light-facing surface is an arc surface protruding outward toward the light source, and a radius of curvature of the first arc line is greater than or equal to 10 micrometers.

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