JPH10123330A - Side light type surface light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evade deterioration of an illumination light correction sheet due to vibration by forming a displacement restriction part which restricts the displacement of a plate type member toward the illumination light correction sheet on a frame. SOLUTION: After a primary light source 23 is held on a light guide plate 2, this light guide plate 2 is arranged on the frame 21. The frame 21 is molded out of, for example, white resin by injection and is composed of a side plate 21A of a thin plate surrounding the periphery of the side light type surface light source device 20 and a bottom surface blocking the side plate 21A from the oblique surface side of the light guide plate 2. Then the displacement restriction part 22 is formed on the frame 21 on the wedge tip side of the light guide plate 2. The displacement restriction part 22 is formed on the bottom surface of the wedge tip side by fixing metal fittings 24 to the bottom surface on the wedge tip side across a double-sided adhesive tape 28, a nearly channel-shaped opening side is arranged facing the inside of the frame 21, and the light guide plate 2 and a reflecting sheet 4 are inserted and arranged. Consequently, the tip end side of the light guide plate 2 is prevented from being displaced greatly owing to vibration, etc., and the tip end side is prevented from colliding against a light diffusion sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sidelight type surface light source device, and more particularly to a sidelight type surface light source device formed such that the thickness of a plate-like member becomes thinner as the distance from the incident surface increases. is there. According to the present invention, a displacement regulating portion for regulating the displacement of the plate-like member toward the illumination light correction sheet is formed in the frame so that the illumination light correction sheet is not deteriorated by vibration, This effectively prevents the deterioration of the quality of the emitted light due to the above.

[0002]

2. Description of the Related Art Conventionally, for example, in a liquid crystal display device,
A liquid crystal display panel is illuminated by a sidelight type surface light source device, thereby reducing the overall shape.

That is, in the sidelight type surface light source device, a primary light source composed of a rod-shaped light source is arranged on a side of a plate-shaped member (that is, composed of a light guide plate), and illumination light emitted from the primary light source is applied to an end face of the light guide plate. More light enters the light guide plate. Further, the sidelight type surface light source device bends the illumination light and emits it from the plane of the light guide plate toward the liquid crystal display panel, whereby the overall shape can be reduced in thickness.

[0004] Such a side light type surface light source device is
A method in which the light guide plate is formed with a substantially uniform thickness,
There is a type in which the thickness of the light guide plate is gradually reduced as the distance from the primary light source increases, and the latter can emit illumination light more efficiently than the former.

FIG. 4 is an exploded perspective view showing an example of the latter sidelight type surface light source device, and FIG.
FIG. 5 is a cross-sectional view taken along line AA of FIG. 4. In this sidelight type surface light source device 1, a primary light source 3 is arranged on a side of a light guide plate 2, and a reflection sheet 4, a light guide plate 2, a light diffusion sheet 5, prism sheets 6 and 7 serving as light control members, weak light. It is formed by sequentially laminating protective sheets 8 made of a sheet material having diffusibility. The primary light source 3 is formed by surrounding a fluorescent lamp 9 composed of a cold cathode tube with a reflector 10, and illuminates the end surface 2 </ b> A of the light guide plate 2 from the opening side of the reflector 10. Here the reflector 10
Is formed of, for example, a sheet material that specularly or irregularly reflects incident light.

The light guide plate 2 is formed, for example, by injection molding acrylic (PMMA resin) into a wedge-shaped cross section, and receives the illumination light of the primary light source 3 from an incident surface 2A which is an end surface. As a result, the light guide plate 2 has a reflection sheet 4 side plane (hereinafter referred to as a slope) 2B and a light diffusion sheet 5 side plane (hereinafter referred to as an exit plane).
2C is repeatedly reflected to propagate the illumination light, and at the time of reflection at the inclined surface 2B and the exit surface 2C, components smaller than the critical angle are emitted from the inclined surface 2B and the exit surface 2C.

Further, the light guide plate 2 has a light diffusing surface 2D formed on a slope 2B. Here, as the light diffusing surface 2D, a light diffusing ink using, for example, magnesium carbonate, titanium oxide, or the like as a pigment is selected so that the degree of light diffusion monotonously increases from the incident surface 2A side toward the wedge-shaped tip. It is formed by adhering. The light diffusing surface 2D may be formed by partially forming the slope 2B on a matte surface (textured surface) instead of the light diffusing ink. Also in this case, similarly, the light diffusing surface 2D
Are formed such that, at a constant pitch, or at random, for example, a rectangular matte area is formed in a rectangular shape, and the area of each rectangular area increases from the incident surface 2A side toward the wedge-shaped tip. As a result, the light guide plate 2 corrects the amount of emitted light that is reduced on the wedge-shaped tip side, and makes the light amount distribution of the emitted light uniform.

Although the illumination light is diffused in this manner, the light guide plate 2 basically includes the inclined surface 2B and the emission surface 2C.
And the illumination light is repeatedly reflected and propagates the illumination light, and the angle of incidence of the illumination light on the emission surface is reduced each time the light is reflected on the inclined surface, and a component having a critical angle or less is emitted from the emission surface 2C. . Therefore, the illumination light emitted from the emission surface 2C is formed such that the main emission direction is inclined toward the wedge-shaped tip.

The reflection sheet 4 is formed of a sheet-like regular reflection member made of a metal foil or the like, or a sheet-shaped irregular reflection member made of a white PET film or the like, and reflects the illumination light leaking from the inclined surface 2B to form the light guide plate 2. , Thereby improving the utilization efficiency of the illumination light.

The prism sheets 6 and 7 are arranged to correct the directivity of the light guide plate 2, and the light diffusion sheet 5 prevents the light diffusion surface 2D of the inclined surface 2B from being recognized from the exit surface 2C side. Light guide plate 2 illuminated by illumination light
Are arranged so as to make the shine, shadow, etc. of each part inconspicuous.

That is, the light diffusion sheet 5 diffuses and emits the illumination light emitted from the light guide plate 2. Each of the prism sheets 6 and 7 is formed of a translucent sheet material such as polycarbonate, and has a prism surface on the surface opposite to the side facing the light guide plate 2. This prism surface is formed by repeatedly forming protrusions having a triangular cross section extending substantially parallel to one direction. In this example, the prism sheet 6 on the light guide plate 2 side is formed.
The prism sheet 7 is arranged so that the projection extends in a direction orthogonal to the incident surface 2A, such that the projection extends in parallel with the incident surface 2A.

Thus, the prism sheets 6 and 7 correct the main emission direction of the emitted light to the front direction of the emission surface 2C on the slopes of the triangular projections. Note that a so-called double-sided prism sheet having a structure in which prism surfaces are formed on both sides may be used as the prism sheet. Thus, in the sidelight type surface light source device 1, the emitted light can be efficiently emitted in the front direction as compared with the sidelight type surface light source device in which the light guide plate is formed with a substantially uniform plate thickness. I have.

The protective sheet 8 protects the surface of the prism sheet 7 from scratches and the like, relaxes the directivity of the emitted light corrected by the prism sheets 6 and 7, and enlarges the viewing angle. Thus, the sidelight type surface light source device 1 emits the illumination light in a desired spread in the front direction of the emission surface. In this way, the light diffusion sheet 5, the prism sheets 6, 7 and the protection sheet 8 constitute an illumination light correction sheet for correcting the characteristics of the emitted light.

In the side light type surface light source device 1 (FIG. 4) having such a basic structure, optical components are integrally held in a predetermined frame 11 and are combined with a liquid crystal display panel. Here, the frame 11 is formed by, for example, injection molding a white resin, and is formed by a thin side plate surrounding the periphery of the side light type surface light source device 1 from the side and a bottom surface closing the side plate from the slope side of the light guide plate 2. Be composed. Thus, the sidelight type surface light source device 1 holds the primary light source 3 at a predetermined position of the frame 11, then sequentially arranges the reflection sheet 4, the light guide plate 2 and the like in the frame, and then the rod-shaped holding member 12 Side and the frame 11 on the primary light source 3 side.

Further, in the side light type surface light source device 1 (FIG. 5), the light diffusing sheet 5
The prism sheets 6 and 7 are stacked and arranged, and a protective sheet 8 is arranged on the prism sheet 7. The protection sheet 8 is fixed to the frame 11 and the holding member 12 by an adhesive tape 28.

[0016]

By the way, when an extreme vibration test is performed on the side light type surface light source device 1 assembled in this way, a case where the emission surface becomes cloudy white or black occurs. When the exit surface is turbid in white or black as described above, the light diffusion sheet 5, the prism sheets 6, 7, or the protection sheet 8 disposed on the exit surface side has some abnormality, and these illuminations are caused. This means that the characteristics of the light correction sheet have deteriorated. Therefore, in the illumination light correction sheet in which the abnormality has occurred, it is difficult to completely correct the characteristics of the emitted light, and accordingly, the quality of the emitted light deteriorates. Specifically, in the prism sheets 6 and 7, when the minute projections having a triangular cross section are crushed, turbidity occurs. When the minute projections are crushed in this way, the directivity of the emitted light is disturbed. .

The present invention has been made in view of the above points, and prevents the illumination light correction sheet from being deteriorated even by vibration, and effectively avoids the deterioration of the quality of emitted light due to the deterioration of the illumination light correction sheet. It is an object of the present invention to propose a side light type surface light source device that can perform the above operation.

[0018]

According to the present invention, in order to solve the above-mentioned problems, illumination light is incident from a light source disposed on an end face of a plate-like member, and this illumination light is bent to exit from the exit surface of the plate-like member. It is suitable for a side light type surface light source device that emits light. In this sidelight type surface light source device, an illumination light correction sheet disposed on the emission surface to correct the characteristics of the illumination light, and a frame holding the plate-shaped member are provided. Forming a displacement restricting portion for restricting the displacement of the plate-like member toward the second position.

At this time, the plate-like member is formed so that its thickness gradually decreases as it goes away from the end face, and the frame is attached to the end where the plate-like member has the smallest thickness, by the displacement control part. To have.

If the frame holding the plate-like member is provided with a displacement regulating portion for regulating the displacement of the plate-like member toward the illumination light correction sheet, the plate-like member vigorously collides with the illumination light correction sheet by vibration. Can not be. Thus, it is possible to effectively avoid a change in the surface shape of the illumination light correction sheet that occurs when the plate member vigorously collides with the illumination light correction sheet, thereby preventing deterioration of the illumination light correction sheet.

At this time, when the plate-shaped member is formed so that the plate thickness is gradually reduced, a displacement regulating portion is arranged at the end where the plate-shaped member has the smallest thickness, and the displacement is most reduced by vibration. The portion where the displacement is severe can be regulated, and the plate member can surely be prevented from violently colliding against the illumination light correction sheet even by vibration.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment FIG. 1 is a sectional view showing a sidelight type surface light source device according to a first embodiment of the present invention in comparison with FIG.
FIG. 2 is a perspective view showing the overall configuration. The sidelight type surface light source device 20 is formed by holding the primary light source 23 on the light guide plate 2 and then arranging the light guide plate 2 on the frame 21.

That is, the reflector 26 is formed by bending a brass plate into a shape having elasticity. Further, the reflector 26 is formed by depositing silver on the inner surface on the side of the fluorescent lamp 9 so that the illumination light emitted from the fluorescent lamp 9 can be efficiently incident on the light guide plate 2. Further, after the entire width of the reflector 26 becomes narrower toward the incident surface 2A, the front end portion protrudes by a minute distance in parallel with the light exit surface and the inclined surface of the light guide plate 2, and the width of the opening at the front end side becomes smaller. 2 is formed smaller than the plate thickness on the side of the incident surface 2A.

Thus, the reflector 26 holds the light guide plate 2 in a state where the reflection sheet 4 and the light guide plate 2 are stacked and held.
Of the light guide plate 2 is clamped by an opening, and then slid along the incident surface 2A of the light guide plate 2 as shown by an arrow D, so that the light guide plate 2 is attached to the light guide plate 2. The reflection sheet 4 is pressed against the light guide plate 2 so as to be held by the light guide plate 2 integrally with the reflection sheet 4 and the fluorescent lamp 9.

The frame 21 holds the light guide plate 2 to which the primary light source has been attached in advance in this way. That is, the frame 21 is formed by, for example, injection molding a white resin, and a thin side plate 21 </ b> A surrounding the periphery of the sidelight type surface light source device 20 and the side plate 21 </ b> A from the slope side of the light guide plate 2.
It consists of a bottom surface that blocks the

Further, the frame 21 has a displacement restricting portion 22 formed on the wedge-shaped tip side of the light guide plate 2 (FIG. 1). Here, the displacement restricting portion 22 is formed by fixing the metal fitting 24 to the bottom surface of the wedge-shaped tip side via the double-sided tape 28. Here, the metal fitting 24 is formed by bending a metal plate material into an elongated rod shape having a substantially U-shaped cross section. Further, the metal fitting 24 is arranged so that the substantially U-shaped opening side faces the inside of the frame 21. In the sidelight type surface light source device 20, the light guide plate 2 and the light guide plate 2 are disposed between upper and lower plate members sandwiching the opening. The reflection sheet 4 is inserted and arranged.

Thus, the displacement restricting portion 22 prevents the front end of the light guide plate 2 from being largely displaced toward the light diffusion sheet 5 even by vibration or the like, whereby the front end does not collide with the light diffusion sheet 5. ing. Thus, in this embodiment, as shown by an arrow E, the tip of the light guide plate 2 in which the primary light source 23 and the like are integrated in advance is inserted into a metal fitting 24, and then, as shown by an arrow F, the tip is supported by a fulcrum. Then, the primary light source 23 and the like are stored in the frame 21 by rotating the primary light source 23 toward the frame 21.

Further, in the frame 21, the side plate 21A on the primary light source 23 side is formed narrower than the other side plate 21A, and claws 21C are formed on the side plate 21A on the primary light source 23 at regular intervals. You. In the side plate 21A on the primary light source 23 side, one end protrudes outward in a rectangular cross section, and a screw hole is formed in the protruding portion.

After the light guide plate 2 and the like are stored in the frame 21, the holding member 2 is attached to the side plate 21 A on the primary light source 23 side.
The light guide plate 2 and the like are held by engaging and screwing 5.

Here, the holding member 25 is formed by injection molding the same resin as the frame 21. The holding member 25 is
After having the nail 25C corresponding to the nail 21C of the frame 21 and storing the light guide plate 2 in the frame 21, the nail 2C of the frame 21 is pressed against the frame 21 from the emission surface side.
The claw 25C meshes with 1C and is held by the frame 21. Further, the holding member 25 has a through hole corresponding to the screw hole of the frame 21, and is fixed to the frame 21 by being screwed with the screw 27 using the through hole and the screw hole while being held by the frame 21. It has been made. As a result, in the sidelight type surface light source device 20, the reflection sheet 4, the light guide plate 2, the primary light source 23
Has been made to hold.

On the exit surface of the light guide plate 2, a light diffusion sheet 5, prism sheets 6, 7 are stacked and arranged, and a protection sheet 8 is arranged on the prism sheet 8. The protection sheet 8 is fixed to the frame 21 and the holding member 25 by the double-sided tape 14.

In the above configuration, the illuminating light emitted from the fluorescent lamp 9 (FIG. 1) directly or after being reflected by the reflector 26 enters the light guide plate 2 from the incident surface 2A, and this illuminating light Propagates inside the light guide plate 2 while repeating reflection between the inclined surface and the emission surface. At this time, every time the illumination light is reflected by the inclined surface, the incident angle with respect to the emission surface decreases, and a component having a critical angle or less with respect to the emission surface is emitted from the emission surface.

The characteristics of the illumination light emitted from the emission surface are corrected by illumination light correction sheets 5 to 8 disposed on the emission surface side. That is, the light is diffused by the light diffusion sheet 5,
Thus, the light diffusing surface 2 formed on the slope 2B of the light guide plate 2
The characteristics are corrected so that printing of D becomes difficult to recognize.
The directivity is corrected by the prism sheets 6 and 7 so that the main emission direction is the illumination direction of the emission surface. Further, the directivity corrected by the prism sheets 6 and 7 is reduced by the protection sheet 8.

In the side light type surface light source device 20, when a vibration test is performed, an acceleration for displacing the light guide plate 2 is given. In the sidelight type surface light source device,
If the light guide plate 2 is displaced in the vertical direction due to the vertical acceleration of the light guide plate 2 and the light guide plate 2 vigorously collides with the light diffusion sheet 5, the light diffusion sheet 5, the prism The surfaces of the sheets 6, 7 are damaged,
It was found that the exit surface was turbid.

However, in the present embodiment, the tip of the light guide plate 2 is
As a result, the tip portion is prevented from colliding with the light diffusion sheet 5 by being held so as not to be displaced in the vertical direction.

On the primary light source 23 side, the primary light source 23 is sandwiched from above and below by the frame 21 and the holding member 25. In this primary light source 23, the width of the reflector 26 once decreases toward the incident surface 2A, and this reflector 26 By holding the light guide plate 2 at the tip of
The vertical displacement is regulated by the reflector 26, so that the primary light source 23 is also prevented from colliding with the light diffusion sheet 5.

As a result, the illumination light correction sheet such as the light diffusion sheet 5 is prevented from being deformed in its surface shape, and the deterioration in characteristics is effectively avoided. Further, in the sidelight type surface light source device 20, the turbidity of the emission surface is thereby prevented, and the deterioration of the quality of the emitted light due to the deterioration of the illumination light correction sheet is effectively avoided.

According to the above configuration, the metal fitting 24 is arranged on the frame 21 and the displacement restricting portion 22 for restricting the displacement of the light guide plate 2 toward the light diffusing sheet 5 is formed. On the other hand, it is possible to prevent the tip of the light guide plate 2 from violently colliding with each other, so that the deterioration of the quality of the emitted light due to the deterioration of the illumination light correction sheets such as the light diffusion sheet 5, the prism sheets 6 and 7 can be effectively prevented. Can be avoided.

(2) Other Embodiments In the above-described embodiment, a case has been described where the metal fittings 24 are arranged on the frame 21 to form the displacement restricting portion.
The present invention is not limited to this, and the displacement regulating portion may be formed by the frame body as shown in FIG. That is, in the sidelight type surface light source device 40 shown in FIG. 3, at the front end side of the light guide plate 2, the emission surface side and the edge of the frame 41 are extended toward the light guide plate 2, whereby the front end side has a cross-section. Form in the shape of a letter. Even in this case, the same effect as in the first embodiment can be obtained.

In the above-described embodiment, the case where the light guide plate 2 is prevented from being displaced by the reflector on the incident surface side is described. However, the present invention is not limited to this. For example, in the case of restricting the displacement of the actuator, various displacement restricting methods can be widely applied.

Further, in the above-described embodiment, the case where the displacement restricting portion is provided on the front end side of the light guide plate is described. However, the present invention is not limited to this, and may be formed on the side surface side of the light guide plate.

Further, in the above-described embodiment, the light diffusion sheet 5, which is an illumination light correction sheet, the prism sheets 6, 7,
Although the case where the protection sheet 8 is sequentially arranged on the emission surface of the light guide plate 2 has been described, the present invention is not limited to this, and the type and number of the illumination light correction sheets arranged on the emission surface may be variously selected as necessary. can do. In this case, for example, instead of arranging two prism sheets each having a prism surface on one surface, arranging only one prism sheet, or further arranging a so-called double-sided prism sheet having prism surfaces formed on both surfaces, Can be widely applied to the case where the prism sheet is removed and the directivity is not corrected at all.

In the above-described embodiment, the case where the frame is made of white resin has been described. However, the present invention is not limited to this case. Thus, the present invention can be widely applied to a case where a frame is configured by using

In the above-described embodiment, the case where the light diffusing surface is formed on the surface facing the light emitting surface of the light guide plate has been described. However, the present invention is not limited to this, and the light diffusing surface may be formed on the light emitting surface of the light guide plate. Or a configuration in which a light diffusing surface is formed on both the light emitting surface and the surface facing the light emitting surface.

Further, in the above-described embodiment, the case where the present invention is applied to a sidelight type surface light source device using a light guide plate formed of a plate-like member having a wedge-shaped cross section has been described, but the present invention is not limited to this. Instead, the present invention can be widely applied to a sidelight type surface light source device in which a light guide plate is formed with a substantially uniform plate thickness.

Further, in the above-described embodiment, the case where the illumination light is incident from one end face has been described. However, the present invention is not limited to this, and the sidelight type surface is also configured to receive the illumination light from the other end face. It can be widely applied to light source devices.

In the above-described embodiment, the case where a rod-shaped light source is used as the primary light source has been described. However, the present invention is not limited to this. The present invention can be widely applied to a sidelight type surface light source device using various light sources, for example, when the primary light sources are formed by arrangement.

Further, in the above-described embodiment, the case where the present invention is applied to the surface light source device of the liquid crystal display device has been described. However, the present invention is not limited to this, and the present invention is not limited to this. It can be widely applied to a surface light source device.

[0050]

As described above, according to the present invention, a displacement regulating portion for regulating the displacement of the plate member toward the illumination light correction sheet is formed in the frame, so that the plate member attached to the illumination light correction sheet is formed. Of the illumination light correction sheet due to vibration can be effectively avoided. Therefore, it is possible to effectively avoid the deterioration of the quality of the emitted light due to the deterioration of the illumination light correction sheet.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a sidelight type surface light source device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the overall configuration of the sidelight type surface light source device of FIG.

FIG. 3 is a sectional view showing a sidelight type surface light source device according to another embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a conventional sidelight type surface light source device.

FIG. 5 is a cross-sectional view of FIG. 4 taken along line AA.

[Description of Signs] 1, 20, 40 Sidelight type surface light source device 2 Light guide plate 5 Light diffusing sheet 6, 7 Prism sheet 8 Protective sheet 10, 26 Reflector 11, 21, 41 Frame 22 Displacement regulating part 24 Metal fitting

Claims (2)

[Claims] 1. A sidelight-type surface light source device that irradiates illumination light from a light source disposed on an end surface of a plate-shaped member to the end surface, bends the illumination light and emits the light from an emission surface of the plate-shaped member, An illumination light correction sheet arranged on an emission surface to correct characteristics of the illumination light, and a frame holding the plate-shaped member, wherein the frame has a configuration in which the plate-shaped member is directed to the illumination light correction sheet side. A side light type surface light source device having a displacement restricting portion for restricting the displacement of the light source. 2. The plate-shaped member is formed such that the plate thickness gradually decreases as the distance from the end surface increases, and the frame includes: an end portion at which the plate-shaped member has the smallest thickness; The side light type surface light source device according to claim 1, further comprising a regulating portion.