JP2000111740A - Illuminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide illuminating device in which the valid use of an illuminating light can be attained, and a reflected light on the edge of a protruding part formed on a light transmission plate can not be seen by an observer by allowing the protruding part to have a face which is almost perpendicular to the traveling direction of an incident light from the light transmission plate, and allowing a boundary between the root of the protruding part and the light transmission place to have an inclination other than a right angle to the incident light. SOLUTION: A protruding part formed on a light transmission plate has a face which is almost perpendicular to the traveling direction of an incident light from the light transmission plate, and a boundary between the root of the protruding part and the light transmission plate has an inclination other than a right angle to the incident light. A twist-shaped protruding part having a top face(the top end side face of the protruding part) 11a at a twisting position to a bottom face (the root side face of the protruding part) 11b is projected like a column with prescribed pitches on the back face of the light transmission plate. In this case, it is desired that an angle θ made by the bottom face 11b and the top face 11a is ranging from 20 to 70 deg.. Also, in this protruding part, the bottom face 11b is formed on the light transmission plate so that the incident angle of an illuminating light from a light source to an edge 11d can be prevented from being 0 deg., that is, an incident angle β of the illuminating light can be a positive acute angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device, and more particularly to an illuminating device capable of illuminating an illuminated surface by disposing a light guide plate capable of emitting light close to the illuminated surface. About.

[0002]

2. Description of the Related Art As an illuminating device that can be used to illuminate an illuminated surface such as a bulletin board or the like that has no light transmission property, a light component in the direction of the illuminated surface is extracted from illumination light incident from just beside a transparent plate. Some have made the illumination surface illuminable. For example,
JP-A-6-289391 and JP-A-6-32433
No. 1 discloses a lighting device including a light source 2 on an end face of a transparent light guide plate 1 provided with a prismatic protrusion 11 as shown in FIG. The light source 2 includes a light emitting body 20 and a protective material 21. The longitudinal direction of the protrusion 11 is formed parallel to the end face of the light guide plate 1. Figure (A)
Is a plan view of the lighting device, and FIG. 2B is a side view of the lighting device. Light emitted from the light source 2 enters from the end face of the light guide plate 1 and is repeatedly reflected between the front surface and the back surface of the light guide plate 1. Of the light that is repeatedly reflected, the light incident on the side surface 11c of the convex portion 11 is not reflected because of a small incident angle, and is emitted to the surface to be irradiated and used as illumination light.

[0003]

However, the above-mentioned prior art has the following problems. For example, as shown in FIG. 4, a part of the light emitted from the light source is refracted by the side surface 11 c of the convex portion 11, emitted in the direction of the irradiated surface, reflected by the irradiated surface 4, and reflected by the observer. It reaches the eyes (light path L ₁ ). On the other hand, the root portion of the convex portion 11, that is, the side surface 11c and the bottom surface 11c
The light reflected by the edge 11d bounding the b proceeds to the viewing direction of the observer, leading to the eyes of the observer depicts an optical path L _2. Since the projections 11 are formed in a row at predetermined intervals on the light guide plate 1, the observer can see the streaks of light, which causes a reduction in contrast and a decrease in visibility.
FIGS. 3A1 and 3A2 are a plan view and a side view showing this state from directly above and from the side.

In order to solve such a problem, the present applicant has devised that the longitudinal direction of the convex portion 11 is formed obliquely to the end face of the light guide plate 1. For example, as shown in FIG. 8, the projection 11 is formed so as to form an angle of α with the end face of the light guide plate 1. FIG. 2A is a plan view of the lighting device, and FIG. 2B is a side view of the lighting device. According to this technique, as shown in FIG. 5, the light reflected by the edge 11d draws the optical path L _4, does not meets the eye of the observer. This is because the edge 11d is α with respect to the end face of the light guide plate 1.
This is because the reflected light does not travel in the direction of the line of sight of the observer. On the other hand, the side surface 11 of the convex portion 11
refracted at c, the illumination light illuminating the illuminated surface 4 draws the optical path L _3, proceeds in a direction different from the viewing direction of the observer. For this reason,
As the incident angle γ to the irradiated surface 4 increases, the effective amount of illumination light in the line of sight of the observer decreases, and the brightness of the irradiated object decreases. FIG. 3 (B1), (B2)
FIG. 3 is a plan view and a side view of the state viewed from directly above and from the side.

In view of the above problems, it is an object of the present invention to provide an illuminating device that makes effective use of illuminating light and that does not allow an observer to see reflected light from an edge 11d of the convex portion 11.

[0006]

An illumination device according to the present invention includes a light source provided so that light can enter the light guide plate from an end surface of the light guide plate having a convex portion formed on one surface. In the lighting device, the convex portion has a surface that is substantially perpendicular to a traveling direction of at least a part of the light incident from the end surface of the light guide plate, and the light can be emitted to a surface to be irradiated. , The boundary with the light guide plate at the root of the convex portion,
It has an inclination other than a right angle to any of the light rays incident from the end face. Preferably, the inclination is between 20 degrees and 70 degrees.
The range of degrees. Further, the convex portion may be configured as a projection having a top surface and a bottom surface at a twist position,
It may be configured as a rod-like body formed in a groove shape on the light guide plate.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a plan view of the lighting device as viewed from behind, and FIG. 1B is a side view. The lighting device includes a light guide plate 1, a light source 2, and an isolator 3. The light guide plate 1 has an optical structure capable of emitting a part of the illumination light incident from the end surface thereof to a surface to be illuminated such as a reflective liquid crystal panel. Specifically, as shown in the enlarged perspective view of FIG.
As shown in FIG. 1A, a plurality of torsion-shaped protrusions 11 having a top surface 11a at a position twisted with respect to b are provided in a row at a predetermined pitch on the back surface of the light guide plate 1. Here, the bottom surface 11b refers to the surface on the base side of the convex portion 11, and the top surface 1b
Reference numeral 1a denotes a surface on the tip side (irradiation surface side) of the convex portion 11. FIG. 2B shows the positional relationship between the bottom surface 11b and the top surface 11a, and the angle θ formed between them is preferably 90 degrees or less, and particularly preferably in the range of 20 degrees to 70 degrees. In addition, the convex portion 11 has an edge 11 against the irradiation light from the light source 2.
2 so that the incident angle at d does not become 0 degree, that is, FIG.
In (B), the bottom 11b is formed on the light guide plate 1 so that the incident angle β of the irradiation light becomes a positive acute angle. By forming the protrusions 11 in this manner, as shown in FIG.
light reflection at d proceeds in a direction different from the viewing direction of the observer depicts an optical path L _6. Optical path L ₆ is substantially the same path as the optical path L ₄ described above. As a result, conventionally, can be reflected light of the edge 11d is due to draw an optical path L _2, erases the streak of light which was generated in the illumination device. Further, as shown in FIG. 2B, the side 11e on the light source 2 side constituting the top surface 11a has an incident angle of 0 degree with respect to the irradiation light from the light source 2 (perpendicular to the irradiation light). The top surface 11a is formed as shown in FIG. The convex portion 11 is formed so such a side 11c of the vicinity of the side 11e is to become substantially perpendicular to the irradiation light from the light source 2 directs light emitted from the light source 2 to the observer through the optical path L ₅ (See FIGS. 3 and 6). This optical path L ₅ is,
Optical path L when convex portion 11 is formed in a prismatic shape as in the prior art
Draw almost the same path as ₁ . As a result, the regular reflection component of the irradiation light emitted from the light source 2 on the surface to be irradiated can be effectively used, and the above-described problem of the related art can be solved. As described above, when the protrusion 11 is configured as a protrusion, the irradiation light from the light source 2 can be multidimensionally controlled by twisting the protrusion. That is, an object of the present invention is to provide an illumination device including a light source provided so that light can be incident into the light guide plate from an end surface of the light guide plate having a protrusion formed on one surface. The problem can be solved by using a twisted shape. FIG. 3 (C
1) and (C2) are a plan view and a side view of this state viewed from directly above and from the side.

The projection 11 has a bottom surface 11b and a top surface 11a.
Is not particularly limited as long as it is formed so as to satisfy the above relationship, and any projection shape can be applied. For example, a shape obtained by twisting a pentagonal prism, a hexagonal prism, or the like may be used. Further, the bottom surface 11b and the top surface 11a do not need to have the same shape, and may have similar shapes. Further, the convex portion 11 can be formed in the light guide plate 1 in a rib shape (or a groove shape). By adjusting the isolator 3, the light source 2
When vertically irradiating light from the end face of the light guide plate 1,
If the rib-shaped convex portion 11 is formed so that the edge 11d has a predetermined inclination with respect to the irradiation light, the bottom surface 11b becomes parallel to the end surface, but the light from the light source 2 is inclined with respect to the end surface. When the light is guided to the edge, the rib-shaped convex portion 11 is formed so that the edge 11d has a predetermined inclination with respect to the light, and thus the bottom surface 11b is formed obliquely with respect to the end surface.

The arrangement direction of the projections 11 is substantially parallel to the end face of the light guide plate 1. In order to make the luminance of the illumination light uniform,
It is preferable that the projections 11 are formed such that the arrangement pitch of the rows formed by 1 gradually decreases according to the distance from the light source 2. Pixel pitch is typically 200 μm to 300 μm
m, when the surface to be irradiated is a liquid crystal panel, the thickness is preferably in the range of 50 μm to 100 μm in order to prevent moire due to interference with pixels constituting the liquid crystal panel.

The light guide plate 1 is made of a material having a higher refractive index than the substance (air in the present embodiment) on the light emission side and having a light transmitting property. For example, it is formed of an acrylic resin, a polycarbonate resin, a transparent resin such as amorphous polyolefin, an inorganic transparent material such as glass, or a composite thereof.
The light guide plate 1 is manufactured by injection molding if it is a resin material, and is manufactured by irradiating light when it has photocurability. Etching is performed in the case of glass or the like. Further, it can also be manufactured by sticking a light diffusing shaped object such as a film having an uneven shape on a resin plate or a glass plate.

The light source 2 has a light-emitting body 20 and a protective material 21 and has a rod shape capable of supplying illumination light from the entire end face of the light guide plate 1. The light source 2 is configured to emit light by supplying power from a power source (not shown). Luminous body 20
For example, a fluorescent tube, a light emitting diode (LED), a semiconductor diode, an incandescent lamp, an EL (electroluminescence) element, or the like can be applied. When used for illumination, the emission wavelength is from 380 nm to 7
Set to about 00 nm.

The isolator 3 is a light beam direction restricting member, and is disposed between the light guide plate 1 and the light source 2 so that the traveling direction of the irradiation light from the light source 2 can be restricted to a fixed exit angle. That is, the isolator 3 has a plurality of slits 31.
Are arranged such that the light irradiation port faces the end face direction. The isolator 3 is formed of, for example, a metal plate or a resin. The exit angle of the light beam can be adjusted by the distance between the light source 2 and the isolator 3 and the diameter of each slit 31. For example, when the light source 2 or the fluorescent tube is used, the emission angle from the fluorescent tube itself is about 84 degrees, but the emission angle can be limited to about 30 degrees by the isolator 3.

The light directivity of a semiconductor laser or the like is good.
When the light source 2 having a small emission angle is used, the isolator 3 can be omitted.

[0014]

According to the present invention, it is possible to provide an illuminating device which can eliminate streaks of light due to reflected light at the edge portions of the projections, has high contrast, and has excellent visibility.

[Brief description of the drawings]

FIG. 1 is a plan view (A) and a side view (B) of a lighting device according to an embodiment.

FIG. 2 is an explanatory diagram of a protrusion according to the embodiment.

FIG. 3 is an explanatory diagram of an optical path drawn by illumination light in a convex portion.

FIG. 4 is an explanatory diagram of an optical path drawn by illumination light in a convex portion.

FIG. 5 is an explanatory diagram of an optical path drawn by illumination light in a convex portion.

FIG. 6 is an explanatory diagram of an optical path drawn by illumination light in a convex portion.

FIG. 7 is a plan view (A) and a side view (B) of a conventional illumination image value.
It is.

FIG. 8 is a plan view (A) and a side view (B) of a conventional illumination image value.
It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide plate 2 Light source 3 Isolator 11 Convex part 11a Top surface 11b Bottom surface 11c Side surface 11d Edge 20 Light emitting body 21 Protective material

Claims (4)

[Claims] 1. An illuminating device comprising a light source provided so that light can enter the light guide plate from an end face of the light guide plate having a convex portion formed on one surface, wherein the convex portion includes the light guide. The light guide plate has a surface substantially perpendicular to the traveling direction with respect to at least a part of the light incident from the end surface of the light plate, and can emit the light to the irradiated surface, and the light guide plate at the base of the convex portion. Has an inclination other than a right angle with respect to any of the light rays incident from the end face. 2. The lighting device according to claim 1, wherein the inclination ranges from 20 degrees to 70 degrees. 3. The lighting device according to claim 1, wherein the projection is a projection having a top surface and a bottom surface at a twist position. 4. The lighting device according to claim 1, wherein the convex portion is a rod-shaped body formed in a groove shape on the light guide plate.