JP2003107474A - Front light and front light type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front light and a front light type display device which are provided with a light guide plate capable of being manufactured in a high yield and uniformly lighting a reflection type display panel. SOLUTION: The light guide plate 3 is configured to comprise a side face 3a opposed to a light source 2 and introducing light rays from the light source 2 to the inside; a rear part 3a reflecting most of light rays whose incident angle is the critical angle of incidence among the light rays introduced to the inside, and transmitting most of the light rays whose incident angle is less than the critical angle of incidence; a front part 3d opposed to the rear part 3c and introducing light ray, and a plurality of projections 6 placed in an introduction direction of the introduced light at a prescribed interval and each of which has a projecting face 6a placed in parallel with the side part 3c and formed within a range of ±10-degrees to the front part 3d with respect to the normal of the front part 3d and has an inclined face 6b formed within a range of ((90-degrees - critical angle) ±10-degrees) from the front part 3d at the side of the light source 2 toward the projecting face 6a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front light for illuminating a reflection type display panel and a front light type display device equipped with this front light.

[0002]

2. Description of the Related Art A front light is effective for illuminating a display portion with low power even when used at night or in a dark environment, and is therefore used in a liquid crystal display device such as a mobile phone or a portable information device. ing. This front light generally uses a light guide plate in which a linear light source or a point light source is arranged on a side surface portion, and the light guide plate converts light from the light source into a surface light source. Then, in order to uniformly illuminate the display portion of the liquid crystal display device and improve the visibility, uniform irradiation light is emitted from the light guide plate to the liquid crystal display panel. As described above, the front light configured to emit the uniform irradiation light from the light guide plate is disclosed in, for example, Japanese Patent Publication No. 3191761 or Japanese Patent Laid-Open No. 2000-250034.
It is disclosed in Japanese Patent Publication (Prior Art).

As shown in FIG. 5, a conventional front light 50 includes a light guide plate 5 facing a reflective display panel 51.
The convex portion 53 having a square shape is provided on the side of the emission surface 52a of No. 2. The light ray 55 emitted from the light source 54 is a light guide plate 5.
The second reflection surface 52b is reflected. Then, a part of the reflected light is emitted from the convex portion 53 to the reflective display panel 51 side and illuminates the reflective display panel 51. In addition, the light guide plate 5
Part of the light propagating inside 2 is reflected from the side surface 52d facing the side surface 52c to the side surface 52c side, and emitted from the convex portion 53. As a result, the reflective display panel 51 is illuminated brightly and uniformly.

[0004]

In the prior art, the convex portion 53 is used.
Must be made into a square shape. Since this square shape has a poor mold release, the square shape is likely to be deformed, and the light guide plate 52
However, there is a problem in that the manufacturing yield of is low.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a front light and a front light type display device having a light guide plate which has a good manufacturing yield and which can uniformly illuminate a reflection type display panel. With the goal.

[0006]

According to the invention of a front light described in claim 1, a light source; a side surface portion which faces the light source and introduces light from the light source into the inside; Among them, a back surface part that reflects most of light having an incident angle of a critical angle or more and transmits most of light of less than the critical angle, a front surface part that faces the back surface and guides light, and a side surface part. A projecting surface that is formed so as to be parallel to the front surface within a range of ± 10 ° with respect to the normal line of the front surface, and from the front surface of the light source side facing this projecting surface (90 ° -critical angle) ± A planar light guide plate having an inclined surface formed at 10 ° and having a plurality of convex portions provided at predetermined intervals in the introduction direction of the introduction light; And a reflection type display panel plate that reflects the light led out from the front face portion to the rear face side of the light guide plate. It is characterized by doing.

"Light having an incident angle of a critical angle or more" means, for example, when the light guide plate is made of acrylic light, the angle between the normal line and the incident direction of the introduced light is 42 ° or more on the back surface. means.

"Make the convex portion parallel to the side surface portion"
Means that the convex portion is provided on the front surface portion over the entire length of the side surface portion. Further, “parallel” does not need to be strictly parallel, and may be substantially parallel.

The "introduction direction of the introduced light" means a direction from the side surface portion facing the light source and introducing the light from the light source into the inside of the light guide plate to the side surface portion facing the side surface portion.

The "predetermined interval in which a plurality of convex portions are provided at a predetermined interval in the introduction direction of the introduced light" may be such that the convex portions are provided at a constant interval, and the convex portion is provided in the introduction direction of the introduced light from the light source side. This means that the distance between the convex portions may become smaller as the distance increases.

"± 10 ° of protruding surface and inclined surface of convex portion"
Since the protruding length of the convex portion is extremely small, for example, about several tens of μm, the manufacturing error and variation of the convex portion are taken into consideration.

Since the protruding surface of the convex portion is substantially orthogonal to the front surface of the light guide plate and the inclined surface is formed between the front surface and the protruding surface, the mold for forming the convex portion sandwiches the convex portion. I am trying. Therefore, the mold for forming the convex portion is easily separated from the convex portion when moved outward. Therefore, since the protrusions are well separated from each other, the protrusions are formed into a predetermined shape, and the manufacturing yield of the light guide plate is improved.

Further, since the protruding surface of the convex portion is substantially orthogonal to the front surface of the light guide plate, the introduced light propagating inside the light guide plate is less likely to be reflected from the protruding surface to the rear surface side. Further, since the inclined surface is formed as a protruding surface from the front surface portion on the light source side, the introduced light propagating through the light guide plate from the light source side is less likely to be reflected from the inclined surface to the rear surface portion side. Therefore, glare is less likely to occur when the reflective display panel is viewed from the outside of the back surface portion.

According to the present invention, since the convex portion provided on the front surface portion is composed of the protruding surface formed on the front surface portion and the inclined surface formed from the front surface portion on the light source side facing the protruding surface,
The mold for forming the convex portion is easily separated from the light guide plate, and the manufacturing yield of the light guide plate is improved. Further, since the convex portion is formed so as not to reflect the introduced light to the back surface side, glare is prevented when visually recognizing the reflective display panel.

Of the reflected light reflected by the back surface of the light guide plate, the light incident on at least the convex portion at an inclination angle (90 ° -critical angle) ± 10 ° or less is a protruding surface or an inclined surface. It is refracted by and guided to the reflective display panel. Further, of the reflected light, a part of the reflected light that is reflected by the front surface portion and again reflected by the back surface portion is led out to the reflective display panel from the next convex portion. That is, the reflected light is derived from the plurality of convex portions, and the reflective display panel is uniformly illuminated.

The light emitted from the convex portion of the light guide plate is reflected by the reflection type display panel, passes through the light guide plate, and is emitted from the back surface portion. The display of the reflective display panel is visually recognized by the light emitted from the back surface portion.

The invention of a front light type display device according to a second aspect comprises the front light according to the first aspect; and a front light type display device main body accommodating the front light. Characterize.

According to the present invention, since the reflection type display panel is provided with the front light uniformly illuminated by the light emitted from the convex portion, the display of the reflection type display panel is easy to visually recognize. Will be provided. Also,
Since the convex portions are easily separated from each other and can be formed into a predetermined shape, the manufacturing yield of the light guide plate is improved and the front light type display panel can be manufactured at a low cost.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described.

1 to 3 show a first embodiment of the present invention, FIG. 1 is a schematic sectional view of a front light, FIG. 2 is a front view showing the shape of a convex portion, and FIG. 3 is a light beam of the front light. FIG.

The front light 1, as shown in FIG.
The light source 2, the light guide plate 3, and the reflection type display panel 4 are provided.

The light source 2 is, for example, a straight tube fluorescent lamp, a plurality of LEDs or a light bulb, and the side surface portion 3 a of the light guide plate 3.
Are disposed so as to face each other. A reflection plate 5 is provided so as to cover the light source 2, and the reflected light emitted from the light source 2 and reflected by the reflection plate 5 is introduced into the inside of the light guide plate 3 from the side surface portion 3a together with the direct light. . Also, the light source 2
Are arranged so that light is uniformly introduced into the side surface portion 3a.

The translucent plate 3 includes side surfaces 3a and 3b and a rear surface 3
c and the front surface portion 3d are made of an acrylic frame body formed in a flat shape, and the front surface portion 3d has a plurality of convex portions 6. And the plate thickness of the light guide plate 3 is 1 to 2 mm.
Is formed in.

The side surface portion 3a faces the light source 2 and introduces the light from the light source 2 into the light guide plate 3. Also, the side surface portion 3a
A white tape (not shown) is attached to the side surface portion 3b facing the side surface 3b so that the light propagating inside the light guide plate 3 is reflected to the side surface portion 3a side.

Of the introduced light (incident light) introduced (incident) into the light guide plate 3, the back surface portion 3c reflects most of the light having an incident angle equal to or greater than the critical angle, and reflects the light less than the critical angle. Most are transparent. Here, since the light guide plate 3 is made of acrylic, the critical angle is about 42 °. Further, the back surface portion 3c is formed in a flat shape, but since it has irregularities on a microscope,
Even light having a critical angle or more is partially transmitted, and light having a critical angle or less is partially reflected. And
The rear surface portion 3c is appropriately set such that the arrangement position of the light source 2 facing the side surface portion 3a is set so that most of the light from the light source 2 is totally reflected.

The front surface portion 3d faces the rear surface portion 3c, reflects most of the reflected light (introduced light) reflected from the rear surface portion 3c, and guides a part thereof to the outside. That is, although the front surface portion 3d is formed in a planar shape, since it is uneven in terms of a microscope, even a part of the reflected light (introduced light) reflected from the rear surface portion 3c is transmitted. Then, most of the introduced light reflected by the front surface portion 3d is reflected again by the rear surface portion 3c. Then, the introduced light is reflected by the back surface portion 3c and the front surface portion 3d and propagates inside the light guide plate 3. Then, when the introduced light reaches the side surface portion 3b, it is reflected by the white tape provided on the side surface portion 3b, and conversely propagates to the side surface portion 3a side.

The convex portion 6 is provided in the front surface portion 3d of the light guide plate 3 so as to be parallel to the planar side surface portion 3a, and is predetermined in the introduction direction of the introduced light, that is, in the direction from the side surface portion 3a to the side surface portion 3b. A plurality of them are provided at intervals, for example, 0.1 to 0.2 mm. And the convex part 6 is formed in the triangular shape which has the protrusion surface 6a and the inclined surface 6b, as shown in FIG. And the protrusion length of the protrusion surface 6a is
It is formed to several tens of μm.

The protruding surface 6a of the convex portion 6 is formed so as to be orthogonal (α = 90 °) to the front surface portion 3d of the light guide plate 3, and the inclined surface 6b faces the protruding surface 6a and faces the light source 2 on the front surface portion 3d. Is formed so as to have an inclination angle of 48 ° (= β) with respect to the front surface portion 3d. The inclination angle β = 48 ° of the inclined surface 6b is
It is a value (90 ° −critical angle) obtained by subtracting the critical angle (42 °) of the introduced light reflected by the back surface portion 3c from the normal line of the front surface portion 3d and the angle of 90 ° with the front surface portion 3d. That is, most of the light reflected by the back surface portion 3 c at a critical angle (42 °) or more and introduced into the convex portion 6 is refracted by the protruding surface 6 a and guided to the outside, that is, the reflective display panel 4. Further, when the light reflected by the back surface portion 3c at a critical angle (42 °) or less is also introduced into the convex portion 6, it is refracted by the protruding surface 6a or the inclined surface 6b and led out to the reflective display panel 4. And the front part 3
Most of the light introduced into d is reflected by the front surface 3d and the rear surface 3c.
Reflected to the side. That is, most of the light not introduced into the convex portion 6 is reflected by the back surface portion 3c and the front surface portion 3d and propagates inside the light guide plate 3 from the side surface portion 3a to the side surface portion 3b.

The protruding surface 6 may be formed within a range of ± 10 ° with respect to the normal line of the front surface portion 3d. That is, the angle α between the front surface portion 3d and the protruding surface 6a is 90 ° ±
It may be formed so as to form 10 °. The angle β between the front surface portion 3d and the inclined surface 6b may be (90 ° -critical angle) ± 10 °. The margin (range) of ± 10 ° is a consideration of manufacturing error and variation because the convex portion 6 has a size of several tens of μm.

As shown in FIG. 1, the reflective display panel 4 is arranged so as to face the front surface portion 3d of the light guide plate 3. The reflective display panel 4 is a liquid crystal display panel, and displays such as characters and patterns are formed on the surface of the light guide plate 3 facing the front surface portion 3d. The reflective display panel 4
Guides the light guided from the front surface portion 3d of the light guide plate 3 to the light guide plate 3
To the back surface 3b side.

Next, the operation of the first embodiment of the present invention will be described.

The light from the light source 2 is applied to the side surface portion 3a of the light guide plate 3.
From the inside, and is totally reflected by the back surface portion 3c. Then, among the reflected light, the inclination angle β of the inclined surface 6b of the convex portion 6 is β = 4.
Light incident at 8 ° or less is projected surface 6a or inclined surface 6b.
It is refracted by and is guided to the reflective display panel 4. Also,
Even if the reflected light is incident on the convex portion 6 at an incident angle of 48 ° or more, the introduced light incident on the protruding surface 6a is
The light is refracted by a and led to the reflective display panel 4. Of the reflected light, the light incident on the front surface portion 3d is partially transmitted through the front surface portion 3d and led out to the reflective display panel 4, most of the light is reflected by the front surface portion 3d, and again the rear surface portion 3c. Is reflected by. Then, a part of the reflected light is transmitted from the next convex portion 6 provided in the introduction direction of the introduction light to the reflection type display panel 4.
Be derived to. In this way, the introduced light is sequentially guided from the convex portion 6 to the reflective display panel 4.

The introduced light that has reached the side surface portion 3b of the light guide plate 3 is reflected by the white tape attached to the side surface portion 3b, reflected by the back surface portion 3c, and reflected from the slanted surface 6b of the convex portion 6 by a reflection type display. Derived to panel 4. FIG. 3 shows a locus of light introduced into the light guide plate 3. The light introduced into the light guide plate 3 passes through the inside of the light guide plate 3 from the side surface part 3a to the side surface part 3a.
b, or when the light guide plate 3 is inside the side surface portion 3b.
From the front surface 3d to the side surface 3a.
It is led to the outside from the convex portion 6 provided on the.

The light mainly derived from the convex portion 6 of the light guide plate 3 is reflected on the surface of the reflection type display panel 4,
The light passes through the light guide plate 3 and is emitted to the outside from the back surface portion 3c.
The light emitted from the back surface portion 3c allows the display content of the reflective display panel 4 to be visually recognized.

The convex portion 6 is formed with a projecting surface 6a projecting within a range of ± 10 ° with respect to the normal line of the front surface portion 3d and the front surface portions 3d to 4 on the light source 2 side facing the projecting surface 6a.
Inclined surface 6 formed at 8 ° (90 ° -critical angle) ± 10 °
Since it is formed in a triangular shape composed of b, by moving the mold forming the convex portion 6 in the normal direction of the front surface portion 3d,
The mold is easily separated from the convex portion 6 of the light guide plate 3. As a result, the convex portion 6 is less deformed and is formed into a predetermined shape, and the manufacturing yield of the light guide plate 3 is improved.

Further, since the projecting surface 6a of the convex portion 6 is substantially orthogonal to the front surface portion 3d of the light guide plate 3, the reflected light incident on the projecting surface 6a is refracted by the projecting surface 6a and is thus a reflection type display panel. 4 and is hardly reflected to the back surface 3c side.
Further, since the inclined surface 6b is formed on the protruding surface 6a from the front surface portion 3d on the light source 2 side, the reflected light from the light source 2 side is less likely to be reflected from the inclined surface 6b to the rear surface portion 3c side. But,
The slanted surface 6b receives the reflected light from the side surface 3b side,
It is easily reflected on the back surface 3c side. However, this reflected light is low in intensity propagated inside the light guide plate 3. Therefore, the convex portions 6 prevent glare when the reflective display panel 4 is viewed from the outside of the back surface portion 3c.

As described above, the light guide plate 3 includes the back surface portion 3c.
The reflected light reflected by the projection surface 6a of the convex portion 6 and the inclined surface 6
Since it is derived from b and is reflected by the front surface portion 3d and propagates inside the light guide plate 3, it is possible to uniformly illuminate the reflective display panel 4 from the front surface portion 3d including the convex portion 6. As a result,
The display of the reflective display panel 4 can be visually recognized well. Further, since the mold for forming the convex portion 6 is easily separated from the convex portion 6 of the light guide plate 3, and the convex portion 6 is formed in a predetermined shape with less deformation, the manufacturing yield of the light guide plate 3 is improved. You can Since the convex portion 6 is formed so as not to reflect the reflected light reflected by the back surface portion 3c to the back surface portion 3c side, the display of the reflective display panel 4 can be visually recognized without causing glare. .

Next, a second embodiment of the present invention will be described.

FIG. 4 shows a front light type display device showing a second embodiment of the present invention, (a) is a front view,
(B) is a cross-sectional view in the AA direction. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

Front light type display device 7 shown in FIG.
Is a mobile phone in which a front light 1 and the like are housed in a mobile phone main body 8 as a front light type display device main body. That is, a board 9 on which various electronic components are mounted is arranged in the mobile phone body 8, and the front light 1 is arranged on the board 9. A protection panel 10 is provided above the front light 1.

The mobile phone body 8 includes a key 11, a flip 12, a microphone 13, a receiver 14, and a battery 15.
Also, the antenna 16 and the like are provided.

Since the mobile phone 7 is provided with the front light 1 on which the reflection type display panel 4 is mainly illuminated by the light led out from the convex portion 6, the reflection type display panel 4 does not generate glare. The display of can be seen well. Further, the mold for forming the convex portion 6 is easily separated from the light guide plate 3, the convex portion 6 is formed in a predetermined shape, and the manufacturing yield of the light guide plate 3 is improved.
Can be provided.

[0044]

According to the first aspect of the present invention, the convex portion is a projecting surface formed within a range of ± 10 ° with respect to the normal line of the front surface section, and the front surface section on the light source side facing the projecting surface. (90 °
-Critical angle) Since it consists of an inclined surface formed at ± 10 °,
It is easy to separate the mold for forming the convex portion from the light guide plate, the deformation of the convex portion is prevented, and the manufacturing yield of the light guide plate can be improved. Further, since the reflected light reflected by the back surface of the light guide plate is led out from the convex portion, the reflective display panel can be uniformly illuminated, and the display of the reflective display panel can be visually recognized well without causing glare. be able to.

According to the invention of claim 2, since the reflection type display panel is provided with the front light which is uniformly illuminated by the light emitted from the convex portion, the display of the reflection type display panel is easy to visually recognize, Further, since the convex portion is well separated from the light guide plate and the manufacturing yield of the light guide plate is improved, an inexpensive front light type display device can be provided.

[Brief description of drawings]

FIG. 1 is a schematic front view of a front light showing a first embodiment of the present invention.

FIG. 2 is likewise a front view showing the shape of a convex portion.

FIG. 3 is likewise a locus diagram of the rays of light of the front light.

FIG. 4 is a front light type display device showing a second embodiment of the present invention, in which (a) is a front view and (b) is a sectional view taken along the line AA.

FIG. 5 is a schematic front view of a conventional front light.

[Explanation of symbols]

1 ... Front light 2 ... Light source 3 ... Light guide plate 7 ... Mobile phone as front light type display device 8 ... Mobile phone body as front light type display device body

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/00 313 G09F 9/00 313 336 336B // F21Y 101: 02 F21Y 101: 02 103: 00 103: 00 F term (reference) 2H038 AA55 BA06 2H089 HA40 KA15 QA11 QA12 TA18 TA20 2H091 FA14Y FA23X FA41X LA11 LA17 LA18 5G435 AA01 AA17 BB12 BB16 EE22 FF06 GG23 HH04 LL07

Claims (2)

[Claims] 1. A light source; a side surface part that faces the light source and introduces the light from the light source into the inside; and a large part of the introduced light introduced into the inside that has an incident angle of a critical angle or more. , A rear part that transmits most of light below the critical angle, a front part that opposes the rear part and guides light, and a front part that is parallel to the side part and is normal to the front part. Has a projecting surface formed within a range of ± 10 ° and an inclined surface formed at (90 ° -critical angle) ± 10 ° from the front surface of the light source side facing the projecting surface. A planar light guide plate having a plurality of convex portions provided at predetermined intervals in a direction; and a light guide plate that is disposed so as to face the front surface of the light guide plate and that is guided from the front surface. And a reflection type display panel plate which is reflected on the back side of the front light. 2. A front light type display device comprising: the front light according to claim 1; and a front light type display device main body accommodating the front light.