JPH10227918A - Light transmission member of surface-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance brightness by obtaining metal mold having lower recessed parts formed to have the high density approximately proportional to the distances from light sources and injection molding a light transmission member formed with numerous post-completion projecting parts by injection molding from a light transparent resin material. SOLUTION: The matrix M having the recessed parts 6 formed to have the high density approximately proportional to the distances from the light sources is obtd. The light transmission member formed with the numerous post-completion projecting parts by injection molding is injection molded from the light transparent resin material. At the time of working the metal mold M by a working machine, a smooth surface 103 forming a rear surface is so formed as to constitute a mirror finished surface. The light sources are disposed on both sides of the light transmission plate 1. In the case both flanks are provided with light incident surfaces, the light transmission plate is so worked as to work the mold recessed parts 102 successively from the central part of the cavity to prevent the work strains from affecting the succeeding working so that the slopes to reflect the light from the light sources may be surely worked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a light guide member of a surface light emitting device used for illuminating a CD (liquid crystal display device) or the like from behind.

[0002]

2. Description of the Related Art When illuminating an LCD or the like having a predetermined area from the back, the first point to be considered is that light generated from a light source is made uniform over all portions of the LCD having a predetermined area. It is mentioned.

[0003] Therefore, conventionally, a light source is arranged on the side of a light guide member formed of a material having high light transmittance, and the light from the light source is guided in the surface direction of the light guide member to form a light guide member. When configured to scatter light emitted from the light emitting surface of the light guide member for the light emitting member arranged in parallel to the light emitting surface,
A large number of projections are formed on the side opposite to the light emitting surface of the light guide member, and while these projections reflect light from the light source, more projections are formed in a portion far from the light source. Many surface light emitting devices in which the brightness of the light emitting surface is uniform have been put to practical use.

According to the surface light emitting device thus configured, the light guide member is mass-produced by injection molding using, for example, an acrylic resin material having high light transmittance. The mold having the cavity is mainly processed by chemical etching.

FIGS. 7A and 7B are an enlarged sectional view of a conventional light guide plate 10 and an enlarged sectional view of an injection mold 201 used for injection-molding the light guide plate 10.

First, in FIG. 7 (b), when a mold concave portion 202 for forming the projection 16 of the light guide plate 10 is formed by chemical etching using an injection mold 201, the bottom surface of the cavity of the mold is formed. A resist film 20 in which portions are provided with opening holes 203a having a predetermined pitch and a predetermined opening area.
3 and then introduce an etchant to open the opening 20.
After the surface contacting via 3a is formed by excavating by erosion, the cavity of the injection mold 201 is formed by removing the resist film 203.

[0007] The injection molding die 2 thus processed and formed.
01 and the thickness H as illustrated in FIG.
The light guide plate 10 having a large number of protrusions 16 formed by injection molding is used to form the light guide plate 10 as described above.
In (a), the light from the light source is reflected, and the projections 16 are formed more in a portion far from the light source so that the brightness on the light emitting surface is uniform.

However, when the mold cavity is machined by the chemical etching process as described above, it is known that the opening hole portion 203a has a hemispherical shape when it is a small-diameter dot, and has a pot-like shape when it is a large-diameter dot. ing.

If so-called over-etching occurs during the chemical etching step, an over-etched portion 202a as shown in FIG. 7B is formed. The diameter d of the protrusion 16b is, for example, Φ0.3.
mm or less and the arrangement pitch is 0.6
mm or less, the communication portion 202b may be formed. Therefore, the protrusion 16 of the light guide plate 10 injection-molded using such a mold has a defective portion 16 as shown in the figure.
a and 16b are formed.

As a result, the light L from the light source cannot be diffusely reflected at the defective portion 16a of the projection 16, or cannot be directed toward the light emitting surface 10a after being reflected by the projection 16, so that light can be efficiently emitted. In addition, it is not possible to select a shape that normally guides the light guide plate away from the light source, so that desired performance cannot be obtained.

Furthermore, in the chemical etching process, it is particularly difficult to control the concentration of the chemical solution, the temperature, and the like. In the case where the density of the projections is provided steplessly, it is very difficult to prevent the occurrence of variation depending on the location. It was difficult. For this,
It is necessary to increase the interval between the adjacent protrusions 16,
The arrangement density of the projections could not be increased, and there was naturally a limit. There was naturally a limit in increasing the amount of light emitted to the outside of the light guide plate to increase the luminance.

[0012]

Therefore, injection molding is performed from a light-transmitting acrylic resin or polycarbonate resin material using an ultra-precision injection molding die that is formed by processing other than the above-mentioned etching, and the above-mentioned projections are formed. By forming a convex portion having an inclined surface of an appropriate shape in the light guide plate, so that incident light incident at a critical angle β or more determined from the resin material can be reflected by the inclined surface of the convex portion, It is conceivable to increase the luminance by directing the light to the light emitting surface.

Accordingly, the present invention has been made in view of the above-mentioned circumstances, and has a light guide plate having a conical shape and other triangular pyramids or four-sided shapes so as to have a high density substantially proportional to the distance from the light source. It is an object of the present invention to provide a light guide member of a surface light emitting device capable of increasing luminance by processing it into an arbitrary shape such as a pyramid, a polygonal pyramid, a roof, and the like.

[0014]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, according to the present invention, a light source is disposed on at least one side of a light-transmitting plate-shaped light guide member,
In order to guide the light from the light source from the side light incident surface to the inside of the light guide member and scatter the light in a diffusion member arranged in parallel with the light emitting surface of the light guide member to perform illumination. A light-guiding member of a surface-emitting device in which a plurality of convex portions having a predetermined shape are formed after completion on the back surface of the light-emitting surface, the concave portion having a high density substantially proportional to the distance from the light source; A mold manufacturing process of obtaining a molding die, and a molding process of injection molding the light guide member having the innumerable convex portions formed by injection molding from a light-transmitting resin material using the molding die. It is characterized by being obtained through.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a main part of a surface light emitting device used for a backlight of a liquid crystal having no self-luminous ability, for example. FIG. 2 is a cross-sectional view of FIG.
FIG.

In FIGS. 1 and 2, the light source unit 4 is formed by bonding a high-intensity light emitting diode (LED) on a substrate 5 and then sealing it with a silicon resin or an epoxy resin. As described above, the electrode section of the substrate 5 is exposed to the outside, and the electrode section is connected to a power supply section (not shown) so that the substrate 5 can be turned on, thereby enabling independent production and supply.

On the other hand, the light guide plate 1 formed in a flat shape as shown in the drawing has substantially the same shape and area as the flat display surface 15 of the liquid crystal. Is formed by injection molding using a transparent acrylic resin, polycarbonate (PC) resin, or the like as the material. The back surface 1b of the light guide plate 1 is formed of a mirror surface, while the inclined surface of the convex portion 6 is made to be a mirror surface or a rough surface so that incident light having a critical angle β or more is totally reflected or irregularly reflected. .

The light-emitting surface 1a, the left and right side surfaces 1d, 1e and the opposite surface 1c and the back surface 1b of the light guide plate 1 are injection-molded so as to be mirror surfaces, respectively, and innumerable projections 6 are regularly formed on the back surface 1b. Is formed. As shown in FIG. 2, the protrusions 6 are arranged so that the horizontal pitch Pw and the vertical pitch Pd are sparse in a portion close to the light source 4, while being separated from the light source 4. As a result, the horizontal pitch Pw and the vertical pitch Pd gradually become denser.

Further, by arranging the convex portions 6 in a staggered manner as shown in the drawing, a simulation using a computer is performed so that the light from the light source 4 can reach the adjacent convex portions 6 without fail. The projections 6 are arranged based on the analysis.

On the other hand, the reflection frame 3 formed in a substantially box shape as shown in the figure is formed in a box shape having a size for accommodating the light guide plate 1 with substantially no gap. Also, this reflection frame 3
Is formed by, for example, injection molding from a white resin or by electroless plating, so that reflection inner surfaces 3a, 3b, 3c, and 3d as reflection surfaces are formed on the inner side, and the light is reflected by each reflection inner surface. The emitted light is directed to the diffusion plate 2.

The above is the schematic configuration of the surface emitting device.
The dimensions are appropriately determined according to the size of the liquid crystal. When the liquid crystal size is large, a fluorescent lamp serving as a line light source is appropriately used as the light source 4. When the backlight is horizontally long, the devices shown in FIGS. 1 and 2 are provided symmetrically to each other so that a pair of the devices face each other, and the projections 6 are arranged so as to be dense at the center. Will be done.

Next, FIG. 3A is a schematic view showing a state of reflection of light L entering the light guide plate 1, and FIG.
FIG. 2B is a cross-sectional view of a main part showing a state of reflection of light L on the convex portion 6.

First, in FIG. 3A, light L emitted from the light source 4 and shown by a broken line in the figure is a critical angle β due to the refractive index n = 1.49 of the acrylic resin. 4
2.16 °, and the light is totally reflected when incident on each surface at an incident angle of 42.16 ° or more. That is, light entering the light guide plate 1 at an angle α formed with a perpendicular from the light guide plate 1 is refracted at the critical angle β, but the refractive index n = s
In the relational expression of inα / sinβ, when α is 90 °,
42. The critical angle β from sinβ = sin (90 °) / n
16 ° will be obtained.

Similarly, in the case of PC resin, since n = 1.59, the critical angle is 38.97 °, and the incident angle 38.97 ° on each surface.
When the light is incident at 97 ° or more, the light is totally reflected.

Therefore, the light L incident from the light incident side surface 1f of the light guide plate 1 formed of an acrylic resin is converted into the left and right side surfaces 1d, 1e at an angle of 47.84 ° or more, which is more than the critical angle.
And the light-emitting surface 1a and the back surface 1b are incident on portions other than the concave portion 6,
All are totally reflected. Similarly, in the case of PC resin, all light incident from the light incident side surface 1f is totally reflected.

The light that reaches the opposite surface 1c while repeating total reflection as described above is emitted from the light guide plate 1 to the outside, is reflected by the reflection inner surface 3b of the reflection frame 3, and then is returned to the light guide plate 1 again. Will be incident.

Next, the most characteristic convex portion 6 of the present invention is:
As shown in FIG. 3 (b), it is formed on the back surface 1b. If the incident angle of the projection 6 with respect to the reflection surface 6a is equal to or greater than the critical angle β, it is formed so as to be totally reflected as shown by a broken line. I have. When the reflection surfaces 6a and 6b are roughened, the light is partially diffused on the reflection surface 6 and travels as indicated by a broken line.

When the incident angle on the light emitting surface 1a is equal to or smaller than the critical angle β, the light is not reflected on the light emitting surface 1a and the light guide plate 1 is not reflected.
Refracted and emitted to the outside, reaches the diffusion plate 2, and diffuses there. In addition, incident light having an incident angle equal to or greater than the critical angle β on the light emitting surface 1a is totally reflected and guided to the far side in the light guide plate.

On the other hand, although not shown, light that has entered the back surface 1b at a critical angle β or less exits from the back surface 1b, is directed to the reflecting surface 3a of the reflecting frame 3, and is reflected by the reflecting surface 3a. After that, the light is again incident on the light guide plate 1 and directed to the light emitting surface 1a.

The light diffused by the diffusion plate 2 as described above forms a surface light source, and in the case of a liquid crystal backlight, passes through the LCD transmission pattern 15 shown in FIG. Will be done.

Further, as shown in the figure, the convex portion 6 is formed so as to protrude in a conical shape from the back surface 1b of the light guide plate 1 so as to be far from the light emitting side surface 1a. And the apex angle θ is 130 ° or less. By forming the convex portion 6 in this way,
Light incident on the back surface 1b at a critical angle β or more,
The light that should be totally reflected and guided by the back surface 1b is totally reflected by the reflecting surface 6a of the convex portion 6, so that the light emitting surface 1a
And the light can be emitted from the light emitting surface 1a.

The projections 6 formed as described above gradually become wider as the distance from the light source 4 increases, as described above.
And the vertical pitch Pd is arranged in a dense state, and furthermore, arranged so as to be staggered as much as possible, so that light from the light source 4 can surely reach the opposite surface 1c.

Various experiments were conducted on the apex angle θ of the protrusions, and it was confirmed that the efficiency was good in the vicinity of 110 ° to 150 °, the best was 120 °, and the height h of the protrusion 6 was 0.1 mm.
The horizontal pitch Pw and the vertical pitch Pd at the portion where the convex portions 6 are provided at the highest density and near the opposite surface 1c shown in FIG. 1 are reduced to 0.3 mm. I was able to get good results.

Next, in the schematic diagram of FIG.
After processing a molding die M having a 02 with a processing machine,
After this is removed, the light guide plate 1 is obtained by injection molding under predetermined conditions using an acrylic resin material or the like in the cavity C. When the molding die M is processed by the processing machine, the smooth portion 103 for molding the back surface is processed so as to have a mirror surface, and the light sources 4 are provided on both sides of the light guide plate 1.
When f is provided on both side surfaces, the mold concave portion 102 is machined in order from the center of the cavity C so as not to affect the machining that is continuously affected by machining distortion, and the inclined surface that reflects light from the light source is formed. It can be processed reliably. Further, when the light source 4 is provided only on one side of the light guide plate 1 and the light incident surface 1f is provided only on one side surface, the mold concave portions 102 are machined in the order of distance from the light source, so that the influence of machining distortion continues. , So that the inclined surface that reflects the light from the light source can be reliably processed.

FIGS. 5 and 6 are tables showing that the convex portions 6 can be formed in any shape. In both figures (a) to (o), external perspective views showing the shape of the light guide plate that is injection molded as the convex portion 6 and the state of reflecting light that has entered at a critical angle or more are shown.

First, in FIG. 5A, the convex portion has a conical shape with an apex angle of 110 ° to 150 °, and is injection molded as a conical convex portion as shown in the figure on the light guide plate. As a result, as described with reference to FIG. 3, light incident at a critical angle β or more can be reflected in the direction of the arrow.

In FIG. 5B, the convex portion is injection-molded as a conical convex portion as shown in the drawing on the light guide plate, and the spherical portion can be configured so as not to be conspicuous. As described above, the light incident at the critical angle β or more is reflected in the direction of the arrow, and the configuration can be such that the spherical portion is not conspicuous.

In FIG. 5C, the light guide plate is injection-molded as a conical convex portion as shown in the drawing, and by appropriately setting the area of the flat portion, the critical angle is increased as described in FIG. It becomes possible to control the amount of light when the light incident above β is reflected in the direction of the arrow.

In FIG. 5D, the light guide plate is injection-molded as a triangular pyramid as shown in FIG. The reflected light can be reflected in the direction of the arrow.

Further, in FIG. 5 (e), the light guide plate is injection-molded as a quadrangular pyramid projection as shown in FIG. The incoming light can be reflected in the direction of the arrow. Therefore, for example, by arranging the light sources on all four side surfaces, it is possible to significantly increase the luminance. In addition, it is also possible to arrange so that light sources of different colors are arranged on four side surfaces and additive color mixing is performed at the convex portions, so that various colors are obtained.

In FIG. 5 (f), a quadrangular pyramid is formed at the tip end as shown in the figure, and further, a spherical shape is formed at the vertex. For this reason, as in the case of FIG. 5B, the spherical portion can be configured so as not to be conspicuous. As a result, the light incident at the critical angle β or more is reflected in the arrow direction as described in FIG. It can be configured such that the spherical portion does not stand out.

In FIG. 5 (g), a quadrangular pyramid is formed at the tip as shown, and a flat portion is formed. For this reason, the light amount can be controlled in substantially the same manner as in FIG.

FIG. 6 (h) shows a gable roof as shown in the figure. As shown in the external perspective view, as shown in FIG. The reflected light can be reflected in the direction of the arrow.

In FIG. 6 (i), the roof-like apex portion of FIG. 6 (h) is formed in a round shape, and the portion is configured so as not to be conspicuous in this portion.

Further, FIG. 6 (j) shows a roof-like structure of a ridge as shown, and as shown in the external perspective view, light incident at a critical angle β or more from the left, right, front and rear directions is reflected in the direction of the arrow. You can do it.

Further, FIG. 6 (k) shows an oval-shaped body at the bottom, which is a roof-like shape of a deformed building as shown in the figure. Light incident at a critical angle β or more can be reflected in the direction of the arrow.

In FIG. 6 (l), the bottom surface is an oval shape, and as shown in the figure, a roof-like shaped portion of a deformed ridge which has an arc surface and a flat surface is formed at the tip. In this case,
As shown in the external perspective view, light that has entered from the front, rear, left, and right directions at a critical angle β or more can be reflected in the direction of the arrow.

Finally, in FIG. 6 (m), the bottom surface is oval, and a trapezoidal long conical shape is formed at the tip as shown. In this case, as shown in the external perspective view, light that has entered from the front, rear, left, and right directions at a critical angle β or more is reflected in the arrow direction.

In FIG. 6 (o), the bottom surface is square, and the inclined surface facing the light source side is formed gently as shown. In this case, as shown in the external perspective view, only light that has entered from the left at a critical angle β or more can be reflected in the direction of the arrow.

As a result of obliquely observing the light guide plate provided with the projections described above, the luminance characteristics obtained can be arbitrarily controlled. As a result, for example, the angle characteristics can be improved as compared to the luminance assurance, or the vertical characteristics can be improved. Arbitrary settings can be made, such as greatly improving brightness.

As described above, when the light guide plate 1 is formed, the shape, size, and the like of the convex portion 6 can be freely set.
It can be confirmed that the arrangement interval of the protrusions 6 can be reduced, and the amount of light emitted from the light guide plate can be increased, so that the brightness is increased about 1.5 times that of the conventional chemical etching. Was.

The light guide plate 1 is used for a backlight for a liquid crystal for a mobile phone, a notebook personal computer or a car navigation device having a larger display screen, and the power consumption of a fluorescent lamp as a light source thereof. Extremely good performance for liquid crystal backlights, which is used when the minimum is desired. Furthermore, the above-mentioned light guide plate can be applied in various other ways, and a light source and a reflection frame are appropriately designed according to the purpose of use of the surface light emitting device using the light guide plate.

[0054]

As described above, according to the present invention,
Brightness is increased by processing the convex part of the light guide plate into a conical shape and other triangular pyramids, square pyramids, polygonal pyramids, rooftops and other arbitrary shapes so that the density becomes high in proportion to the distance from the light source The light guide member of the surface light emitting device which can achieve the above can be provided.

[0055]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a surface light emitting device.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3A is a schematic diagram illustrating a state of reflection of light L entering a light guide plate 1; (B) is the light L at the convex portion 6
FIG. 5 is a cross-sectional view of a main part showing a state of reflection of the light.

FIG. 4 is a process chart of injection molding.

FIG. 5 is a list showing that a convex portion can be forged into an arbitrary shape.

FIG. 6 is a table showing that a convex portion can be forged into an arbitrary shape.

FIG. 7A is an enlarged sectional view of a conventional light guide plate 10;
FIG. 2B is an enlarged cross-sectional view of an injection mold 201 used for performing injection processing on the light guide plate 10.

[Explanation of symbols]

 Reference Signs List 1 light guide plate, 2 diffusion plate, 3 reflection frame, 4 light source, 5 substrate, 6 convex part, M molding die, β critical angle

Claims (5)

[Claims] 1. A light source is disposed on at least one side of a light-transmitting plate-shaped light guide member, and light from the light source is guided from the side light incident surface into the light guide member. In order to illuminate by scattering light in a diffusion member arranged in parallel with the light emitting surface of the light guide member, a surface emitting device having an infinite number of convex portions having a predetermined shape formed on the back surface of the light emitting surface. A light guide member, a mold manufacturing process for obtaining a molding die having a concave portion having a high density substantially proportional to the distance from the light source, light transmittance using the molding die A light-guiding member for a surface-emitting device, which is obtained through a molding step of injection-molding the light-guiding member having a myriad of projections formed after completion by injection molding from a resin material. 2. The method according to claim 1, wherein the predetermined shape is set so that incident light incident at a critical angle β or more determined from the resin material is reflected to the light emitting surface on the inclined surface of the completed convex portion. The light guide member of the surface light emitting device according to claim 1, wherein the back surface is a mirror surface. 3. A vertex angle in the range of 110 ° to 150 °, preferably a 120 ° conical surface, or a triangular, square, polygonal, or trapezoidal shape for forming the inclined surface of the convex portion after completion. The light guide member of the surface light emitting device according to claim 2, wherein the light guide member has an arbitrary shape in which a long cone, a gable, and a ridge roof surface are formed. 4. The light guide member of a surface light emitting device according to claim 3, wherein the convex portion has an arbitrary shape in which a spherical portion or a flat portion is formed at a tip portion of the completed convex portion. 5. The light guide member of a surface light emitting device according to claim 3, wherein the inclined surface of the convex portion after completion has an arbitrary shape formed only at a portion facing the light source.