JPH095529A - Light transmission plate and surface type illuminating body using the same - Google Patents

Abstract

PURPOSE: To reduce the cost of a backlight device by reducing the number of directional sheets required by two in the conventional device to one without deteriorating luminance performance by forming a projected line whose ridge line is perpendicular or inclined to a light entering end face and whose cross section is inverted V shape on a light exiting surface. CONSTITUTION: The projected line 8 whose ridge line 9 is perpendicular or inclined to the light entering end face S1 and whose cross section is an inverted triangle is formed on the light exiting surface S2. The projected line 8 has a function for guiding light introduced in a light transmission plate 1 to the inside of the plate 1, and a function for condensing the light, whose light exiting angle distribution in a direction parallel with the end face S1 may be that in a direction perpendicular to the surface S2, out of the light reflected and scattered in the plate 1 and exiting from the surface S2. Therefore, the projected line 8 functions similarly to the conventional directional sheet set so that the groove train thereof may be in a right angle direction to the end face S1, whereby it is possible to omit the directional sheet and it is enough to use only another directional sheet 3a2. Thus, the number of directional sheets which are required by two in the conventional device is reduced to one.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge light type light guide plate and an improvement of a surface illumination body using the light guide plate.

[0002]

2. Description of the Related Art This type of light guide plate (1) is a light emitting surface (S2) with a large area that scatters light from a cold cathode tube which is a light source (2) arranged along a light incident end surface (S1). It is widely used as a surface light source of a planar lighting body (B) that uniformly illuminates a wide display surface, and is widely used as a backlight device for liquid crystal display devices in recent years as well as for displaying advertising lights, etc. It is used.

The above-mentioned conventional edge light type light guide plate
(1) is acrylic resin flat plate or wedge type (single lamp type) to V
Type (two-lamp type) is used, white dots (6) are printed on the reflecting surface (S3) or grain is formed, and the reflecting sheet (4) is formed along the reflecting surface (S3). ), And the light output surface (S
2) side, diffusion sheet (3b) and two directional sheets
(3a1) and (3a2) were placed so as to overlap each other. The directional sheet (3a1) (3a2), a large number of groove rows (11) (12) are respectively formed in parallel, one directional sheet (3a1),
The groove array (11) is arranged perpendicular to the light incident end surface (S1), while the groove array (12) of the other directional sheet (3a2) is arranged parallel to the light incident end surface (S1). Therefore, high brightness was achieved. In addition, a reflector (7) is arranged behind the light source (2), and the light reflection end face (S4) of the light guide plate (1) << including the side face part of the light guide plate (1) >> is end face reflection. A tape (5) is provided.

As described above, in the conventional structure, the two directional sheets (3a1) and (3a2) are always required.
Not only are the (3a1) and (3a2) expensive, but the work of incorporating them into the backlight device (B) requires manpower, increasing the cost of the backlight device (B) as a whole.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the conventional light guide plate, and requires two directional sheets which are conventionally required without lowering the luminance performance. It is to achieve the cost reduction of the backlight device by using one sheet.

[0006]

A light guide plate (1) according to claim 1 "scatters light incident from a light source (2) disposed on a light incident end surface (S1) and emits the light (S2). Light guide plate that emits light from (1)
And the ridge line (9) is perpendicular or inclined to the light incident end surface (S1) and has a V-shaped cross section.
It is formed in (S2) ”.

When a ridge (8) whose ridgeline (9) is perpendicular or inclined to the light incident end surface (S1) and whose cross section is an inverted V shape (or triangle) is formed on the light exit surface (S2), The ridge (8) has a function of guiding the light introduced into the light guide plate (1) to the back of the light guide plate (1),
Of the light emitted from the light exit surface (S2) after being reflected and scattered inside the light guide plate (1), the exit angle distribution in the direction parallel to the light entrance end surface (S1) is collected in the direction perpendicular to the light exit surface (S2). Since it has the function of shining, this ridge (8) is a conventional directional sheet (3) installed such that the groove array (11) is at a right angle to the light incident end surface (S1).
a1), so this directional sheet (3a1) can be omitted and the other directional sheet (3a2) `` The groove row (12) of this directional sheet (3a2) is the It is installed so that it is almost parallel to the end surface (S1). " As a result, two directional sheets (3a1) and (3a2), which were required in the past, can be replaced by one sheet (3a2), which enables a significant cost reduction.

<Claim 2> states that the apex angle of the ridge (8) is 30 °.
˜150 ° (preferably 50 ° to 110 °), and the included angle between the ridgeline (9) of the ridge (8) and the light incident end surface (S1) is 70 ° to 90 °.
And the pitch between the ridges (8) is 10 μm to 600 μm
It is characterized in that "Claim 3" is that "the slopes forming the ridges (8) are processed into an optical mirror surface state".

According to a surface type illumination body (A) of claim 4, "the light guide plate (1) according to any one of claims 1 to 3 and a light incident end face (at least one end of the light guide plate (1) ( A light source (2) arranged along S1), and a reflector (7) arranged behind the light source (2) and condensing light from the light source (2) on the light incident end surface (S1), A sheet of diffusion sheet (3b) disposed on the light exit surface (S2) of the light guide plate (1) and its groove array (12) installed substantially parallel to the light entrance end surface (S1). Directional sheet (3a2), the reflection sheet (4) disposed along the reflection surface (S3) on the opposite side to the light exit surface (S2) of the light guide plate (1), and the light guide plate (1). It is composed of an end face reflection tape (5) arranged on the light reflection end face (S4) ”.

By using the light guide plate (1) of the present invention, the conventional directional sheet (3a1) can be omitted, and the manufacturing cost of the backlight device (A) can be greatly reduced.

[0011]

The present invention will be described in detail below with reference to the illustrated embodiments. First, various examples of the light guide plate (1) used in the present invention and a planar illuminator (A) using the light guide plate (1) will be described. As shown in FIGS. 1 and 2, the first embodiment of the light guide plate (1) is formed in a wedge shape, the reflective surface (S3) is provided with white printed dots (6) or grain, and the light emitting surface (6) is further provided. A large number of ridges (8) whose ridges (9) are perpendicular or inclined to the light incident end surface (S1) and whose cross section is an inverted V shape (in other words, an isosceles triangle) are formed in parallel in S2). It is an example. The apex angle of the ridge (8) is 30 ° to 150 ° (preferably 50 ° to 110 °), and the included angle n between the ridgeline (9) of the ridge (8) and the light incident end surface (S1) is 7
0 ° to 90 ° and the pitch between the ridges (8) is 10 μm
It is 600 μm. Also, the slopes (10) that make up the ridges (8)
Is processed into an optical mirror surface state.

As shown in FIG. 1, the wedge-shaped light guide plate (1) has a wide light incident end surface (S1) and a narrow light reflection end surface (S4) opposite to the light incident end surface (S1). It is formed on both ends (S
1) The reflecting surface (S3) is formed so as to be inclined with respect to the light emitting surface (S2) between (S4), and its cross section is formed to have a wedge shape. (Note that the light-incident end surface of the light guide plate (1) (S
The side surface between 1) and the light-reflecting end surface (S4) also reflects light here, so it is shown as (S4), but the end surface reflection tape (5) does not necessarily have to be provided on the side surface portion. ) In this embodiment, the light exit surface (S2) is perpendicular to the light entrance end surface (S1), and the reflection surface (S3) is inclined with respect to the light entrance end surface (S1). However, conversely, the light exit surface (S2) is the light entrance end surface (S1).
It is needless to say that the reflecting surface (S3) may be inclined with respect to the light incident end surface (S1) at a right angle. As a material, an acrylic plate having excellent light transmission is generally used.

A cold cathode tube which serves as a light source (2) is arranged along the light incident end surface (S1) of the wedge-shaped light guide plate (1). Behind the cold cathode tube (2), a reflector (7) formed in a concave surface is generally installed. Furthermore, a reflection sheet (4) is installed on the lower side of the reflecting surface (S3) of the wedge-shaped light guide plate (1).
On the 2), one directional sheet (3a2) and one scattering sheet (3b) are installed. A large number of groove rows (12) are formed in parallel on the directional sheet (3a2) so that the groove rows (12) are parallel or slightly inclined to the light incident end surface (S1) of the wedge-shaped light guide plate (1). Is installed in. That is, in general, when the ridge (8) formed on the light exit surface (S2) of the wedge-shaped light guide plate (1) is at a right angle to the light incident end surface (S1), in order to prevent the occurrence of the moire phenomenon. The directional sheet (3a2) is arranged such that the groove array (12) is slightly inclined with respect to the light incident end surface (S1) of the wedge-shaped light guide plate (1), and conversely, the light output surface of the wedge-shaped light guide plate (1). When the ridges (8) formed in (S2) are formed to be inclined with respect to the light incident end surface (S1), the directional sheet (3a2) has a groove array (12) in a wedge-shaped light guide plate ( 1) Light incident end face
It is placed so that it is parallel to (S1). Of course, when the ridge (8) is perpendicular to the light incident end surface (S1), the groove array (12) of the directional sheet (3a2) becomes parallel to the light incident end surface (S1) of the wedge-shaped light guide plate (1). As described above, or when the ridges (8) are inclined with respect to the light incident end surface (S1), the groove array (12) also has the wedge light guide plate (1) light incident end surface (S).
You may arrange so that it may incline to 1).

A part of the light emitted from the light source (2) is part of the light incident end surface (S
The light is directly incident on 1), and the rest is reflected by the reflector (7) and incident. The incident light travels straight in the wedge-shaped light guide plate (1), and most of the light is reflected by the reflection surface (S3) or the reflection sheet (4), its course is changed, and countless reflections are repeated. Most of the light is emitted from the light emitting surface (S2). Part of the light that is incident substantially parallel to the light emitting surface (S2) or the reflecting surface (S3) is reflected on the reflecting surface (S3).
It is reflected by the end face reflection tape (5) arranged on the light reflection end face (S4) without being reflected by the light reflection end face (S1), and is reflected again by the reflector (7). The course has changed, and the light is finally coming out.

Here, since the ridge (8) is formed so that its ridgeline (9) is inclined at a right angle or at an included angle n (70 ° to 90 °) with respect to the light incident end surface (S1), The light introduced into the light guide plate (1) by the ridges (8) is guided to the back of the light guide plate (1) and reaches the light reflection end surface (S4). At the same time, among the lights emitted from the light exit surface (S2), the light exit angle distribution in the direction parallel to the light entrance end surface (S1) is condensed in the direction perpendicular to the light exit surface (S2). Then, the groove row (12) of the directional sheet (3a2) installed on the ridge (8).
Is installed so that it is almost parallel to the light incident end surface (S1), so here the exit angle distribution in the direction perpendicular to the light incident end surface (S1) is changed to the direction perpendicular to the light exit surface (S2). It will collect light. As a result, the light output angle distribution of the light passing through the directional sheet (3a2) is focused on the optical axis perpendicular to the light output surface (S2). When the condensed light is too sharp, the diffusion sheet (3b) is installed on the directional sheet (3a2), and the diffusion sheet (3b) diffuses the light uniformly, and as a result, the light emitting surface (S2 ) Will be emitted uniformly and with high brightness. If it is not too sharp, the diffusion sheet (3b) can be omitted.

In the above description, the case where the light guide plate (1) is wedge-shaped has been described as an example, but of course, the present invention is not limited to this, and a one-lamp parallel plate type (not shown) or a two-lamp parallel plate type is used. Various things such as a thing (not shown) or a two-lamp type V type as shown in FIG. 5 are also included. Further, the material of the light guide plate (1) is preferably an acrylic plate as described above, but is not limited to this, of course,
Any material may be used as long as it has excellent light transmittance. Further, in the above, the case where the light guide plate (1) is transparent is taken as an example, but it is needless to say that the present invention is not limited to this, and may be an in-conductor diffuser plate in which fine particles are diffused.

(Embodiment 1) A 1-lamp type wedge-shaped light guide plate having an area of 10.4 "is provided with a wrinkle having a high density (the density becomes higher as it goes away from the light incident end face) to make the brightness distribution uniform. A convex row with a pitch of 40 μm and an apex angle of 90 ° is inclined on the light emitting surface at an angle of 5 ° (angle n = 85 °) with respect to the vertical line of the light receiving end surface (S1) on the cold cathode tube side. So formed.
Further, one directional sheet << BEF90 (trade name) so that the groove array on the light exit surface (S2) is parallel to the light entrance end surface (S1).
A vertical angle of 90 ° manufactured by Sumitomo 3M Co., Ltd. was provided to form a backlight device (A). "A revic tape (trade name), a reflector, and a diffusion sheet are also incorporated as an end face reflection tape. The luminance performance of the backlight device (A) thus formed was measured and found to be 1,450 cd / m ² .

(Comparative Example) A light emitting surface (S
2) Uses a normal single-lamp wedge-shaped light guide plate, and two directional sheets (3a1) (3a2) on the light emitting surface (S2)
EF90 vertical angle 90 ° made by Sumitomo 3M Co., Ltd.
Luminance performance was measured by arranging one groove array (11) at right angles to the light incident end surface (S1) and the other groove array (12) in parallel. The luminance performance in this case was 1,470 cd / m ² .
Therefore, the backlight device (A) according to the present invention and the conventional backlight device (B) have almost the same brightness performance, but the manufacturing cost can be significantly reduced.

[0019]

As described above, on the light exit surface of the light guide plate of the present invention, the ridges whose ridge lines are perpendicular or inclined to the light incident end surface and whose cross section is an inverted V shape are formed. Therefore, the light introduced into the light guide plate by the convex strip is guided to the back of the light guide plate, and at the same time, of the light emitted from the light exit surface,
Since the light output angle distribution in the direction parallel to the light incident end surface is condensed in the direction perpendicular to the light output surface, it performs the same function as one of the two directional sheets that has been conventionally required. As a result, it is possible to omit the functionally same directional sheet, and it is possible to significantly reduce the cost of the backlight device.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment of a planar lighting body according to the present invention.

FIG. 2 is a schematic sectional view of FIG.

FIG. 3 is a plan view of FIG.

FIG. 4 is an enlarged perspective view of a ridge portion of FIG.

FIG. 5 is a perspective view of a second embodiment of the planar illuminator according to the present invention.

FIG. 6 is a perspective view of a conventional example.

[Explanation of symbols]

 (1) ... Light guide plate (2) ... Light source (6) ... White dot (8) ... Convex line (9) ... Ridge line (S1) ... Light entrance end face (S2) ... Light exit face (S3) ... Reflection face (S4) … Light-reflecting end face

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[Procedure amendment]

[Submission date] August 30, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

6. The light guide plate is a diffusion type in a conductor.
The planar illumination body according to claim 4, which is characterized in that. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 29, 1996

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Title: Light guide plate and planar illuminator using the light guide plate

Claims (4)

[Claims] 1. A light guide plate that scatters light incident from a light source disposed on a light incident end surface and emits the light from the light exit surface, and its ridge line is perpendicular or inclined to the light incident end surface and A light guide plate, characterized in that a convex strip having an inverted V-shaped cross section is formed on the light emitting surface. 2. The light guide plate according to claim 1, wherein the ridges have an apex angle of 30 ° to 150 °, and the ridgeline of the ridges and the light incident end face have an included angle of 70 ° to 90 °. A light guide plate, wherein the pitch between the ridges is 10 μm to 600 μm. 3. The light guide plate according to claim 1, wherein the slanted surface forming the convex stripe is processed into an optical mirror surface state. 4. The light guide plate according to claim 1, a light source arranged along at least one end of the light guide plate along a light incident end surface, and a light source arranged behind the light source. A reflector for condensing light from the light source on the light incident end surface, a diffusion sheet arranged on the light exit surface of the light guide plate, and a groove array thereof are installed substantially parallel to the light incident end surface.
It is composed of a directional sheet, a reflection sheet arranged along a reflection surface opposite to the light exit surface of the light guide plate, and an end face reflection tape arranged on the light reflection end face of the light guide plate. A planar lighting body characterized by being present.