JPH10172321A - Manufacture of light guide member and surface light emitting device using thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately form a protrusion of a light guide plate, and to increase the brightness and a whole surface light emitting device, by injection molding of a light transmissive resin, using a mold member obtained by forming a recess having a tilted face to a material having a smooth face, machining the smooth face and the recess to obtain a prescribed roughness, and provided only the smooth face with a mirror finished surface. SOLUTION: All the mold recesses 102 to be used as cavities for molding protrusions, are successively cutted and machined by a cutting tool 30, and then a face farther from a light source of the protrusions, of a tilted face devoted for reflection, is machined with an accurate vertical angle. The abrasive grain of a given grain size is injected from a sand blast nozzle 300 to the material 101a, to roughen both of the smooth face 103 and the mold recess 102, then the roughened smooth face 103 is ground by a grinder 301, and the complete mirror finished surface is formed on the smooth face by the polishing. The material 101a having only the roughened face on the mold recess 102 face, is removed, to be integrated with a block member of a mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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 protrusions are formed on the side opposite to the light emitting surface of the light guide member, and while these protrusions reflect light from the light source, light is emitted such that more protrusions are formed in portions far from the light source. Many surface light emitting devices having a uniform surface brightness have been put to practical use.

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

FIG. 11 is an enlarged sectional view (a) of a conventional light guide plate 10 and an enlarged sectional view (b) of an injection mold 201 used for injection-molding the light guide plate 10.

First, in FIG. 11B, when a mold concave portion 202 for forming the protrusion 16 of the light guide plate 10 by an injection mold 201 is formed by chemical etching, the bottom surface of the cavity of the mold is used. 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.
11B, the light guide plate 10 having a thickness H as shown in FIG. 11B and having a large number of projections 16 formed thereon is injection-molded. Light emitting surface 1
At 0a, while the light from the light source is reflected, more projections 16 are formed in a portion far from the light source so that the brightness on the light emitting surface becomes uniform.

[0008]

However, when the mold cavity is machined by chemical etching as described above, the opening hole portion 203a becomes hemispherical when it is a small-diameter dot, and has a pot bottom shape when it is a large-diameter dot. Is known to be.

If so-called over-etching occurs during the chemical etching step, an over-etched portion 202a as shown in FIG. 11B is formed. The diameter d of the projection 16b is, for example, Φ0.5.
mm or less and the arrangement pitch is 1 mm
If the width becomes narrower below, the communication portion 202b may be formed. Therefore, the defective portions 16a, 1
6b will be 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, and there was a limit in increasing the amount of light emitted to the outside of the light guide plate to increase the luminance.

In view of the above, the above-mentioned projection is accurately formed into a conical shape having an inclined surface by injection molding from a light-transmitting resin material using an ultra-precision injection molding die which is formed by processing other than the above-mentioned etching. Then, it is conceivable to increase the luminance by reflecting the incident light incident at a critical angle β or more determined by the resin material on the inclined surface and directing the incident light to the light emitting surface.

However, when each of the projections is formed in a conical shape as described above, since the directivity of the light reflected by the inclined surface of the projection is strong, the light is matched with the reflected light that does not match the normal direction of the light emitting surface. Due to the difference in the reflected light, the projections appear in a dot state from the light emitting surface side. To prevent this, a diffusion plate having a high diffusivity is required, and the brightness of the entire surface light emitting device is increased. Sometimes it was difficult.

Therefore, the present invention has been made in view of the above-mentioned problems, and accurately forms a projection formed on a light guide plate, and light reflected by an inclined surface of the projection goes to a light emitting surface. When enhancing the directivity, it is possible to prevent the projections from appearing in a dot state from the light emitting surface side, to enable the use of a diffusion plate having a low diffusion rate, and to increase the brightness of the entire surface light emitting device. It is an object of the present invention to provide a method for manufacturing a light guide member and a surface light emitting device using the light guide member.

[0015]

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 a side or both sides of a light-transmitting plate-shaped light guide member, and light from the light source is incident on the light guide surface of the light guide member. In order to illuminate the inside by diffusing light with a diffusion member arranged in parallel with the light emitting surface of the light guide member, an infinite number of protrusions are formed on the back surface of the light emission surface of the light guide member. A method of manufacturing a light guide member for making the brightness of the diffusion member uniform over the entire surface, wherein a mold member for molding the protrusions and the back surface is formed on a material having a smooth surface. A concave portion having an inclined surface is formed by cutting sequentially with a cutting tool having an angle θ, and the smooth surface and the concave portion are processed into a rough surface having a predetermined roughness by a rough surface processing method including a sand blast method, Using the mold member having only the smooth surface as a mirror surface by a mirror processing method including a polishing process, Manufacturing a light guide member such that incident light incident at a critical angle β or more determined from the resin material is diffused toward the light emitting surface on the inclined surface by injection molding from a transient resin material. It is characterized by.

Further, a light source is disposed on the side or both sides of the light-transmitting plate-shaped light guide member, and the light from the light source is guided inside from the light incident surface of the light guide member. In order to scatter and illuminate light with a diffusion member arranged in parallel with the light emitting surface of the light guide member, countless protrusions are formed on the back surface of the light emission surface of the light guide member, and the brightness of the diffusion member is reduced. A surface light emitting device using a light guide member that makes the light guide member uniform over the entire surface, wherein the protrusion has an inclination angle γ that is a normal to the back surface of the light guide member and includes an inclined surface formed of a rough surface. And a light guide member that forms the rear surface with a mirror surface and diffuses incident light incident at a critical angle β or more determined from the resin material toward the light emitting surface on the inclined surface. .

[0017]

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

First, FIG. 1A is a cross-sectional view showing a main part of a surface light emitting device used for, for example, a liquid crystal backlight having no self-luminous ability. FIG. 1 (b)
FIG. 2 is an enlarged sectional view showing a main part of the light guide plate 1. FIG. 2 is a sectional view taken along the line XX of 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 planar light guide plate 1 has substantially the same shape and area as the planar display surface 15 of the liquid crystal, and accommodates the pair of light source units 4 on the light incident side surface 1f. In addition to forming the shape portion, the material is injection-molded using a transparent acrylic resin, polycarbonate (PC) resin, or the like as the material.

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 as described later so as to be mirror surfaces, respectively.
An innumerable projection part 6 is regularly formed on the upper part.

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 As the distance increases, the horizontal pitch Pw and the vertical pitch Pd gradually increase
Are arranged in a staggered shape as shown in the figure, so that the light from the light source 4 can reach the distant portion of the adjacent protrusion 6 without fail. The protrusions 6 are provided based on.

On the other hand, the reflection frame 3 formed in a substantially box shape as shown in the figure is formed so as to have a size and shape capable of accommodating the above-mentioned light guide plate 1 with almost no gap. Also, this reflection frame 3
For example, a reflection inner surface 3 as a reflection surface formed by injection molding from a white resin or by electroless plating.
a, 3b, 3c, and 3d are provided so that the light reflected on each reflection inner surface is directed to the diffusion plate 2.

The above is the schematic configuration of the surface emitting device.
The size is appropriately determined according to the size of the liquid crystal. In the case of a large size, a fluorescent lamp serving as a line light source may be used as the light source 4. In the case where the backlight is horizontally long, the devices shown in FIGS. 1 and 2 are provided symmetrically to each other so that one pair faces each other, and the projections 6 are arranged so as to be dense at the center. You may do it.

FIG. 3A is a schematic diagram showing how light L entering the light guide plate 1 is reflected, and FIG. 3B is a main part showing how light L is reflected on the projection 6. It is sectional drawing.

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 has an angle β of 42.16 ° or less, the light emitting side surface 1a, and the left and right side surfaces 1a.
d, 1e and the incident angle 4 at portions other than the protrusion 6 on the back surface 1b.
Above 7.84 ° the critical angle is exceeded and all are totally reflected.
Similarly, in the case of PC resin as well, all the light incident from the incident side surface 1f is totally reflected.

The light that reaches the opposite surface 1c while repeating the 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 1c. Will be incident.

Next, the projection 6 which is the most characteristic of the present invention.
Is formed on the back surface 1b as shown in FIG. 3 (b). If the incident angle of the projection 6 with respect to the reflecting surface 6a is equal to or larger than the critical angle β, the light is scattered on the rough reflecting surface and then broken. It is directed to the light emitting surface 1a as shown. When the incident angle with the light emitting surface 1a is equal to or less than the critical angle β, the light is refracted and emitted directly from the light guide plate 1 to the outside without being reflected, and reaches the diffusion plate 2,
There it spreads. In addition, the incident angle at the light emitting surface 1a is the critical angle β.
If it is above, the light is totally reflected and the light is guided inside the light guide plate 1 sequentially.

On the other hand, the light incident on the back surface 1b at a critical angle β or less exits from the mirror back surface 1b and is reflected by the reflection frame 3b.
Are directed toward the reflecting surface 3a, reflected by the reflecting surface, and again incident on the light guide plate 1, and then directed to the light emitting surface 1a.
When the incident angle with respect to the light emitting surface 1a becomes equal to or smaller than the critical angle β, the light exits from the light guide plate 1 and diffuses by the diffusion plate 2.

The light diffused by the diffusing 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 to perform display.

The projection 6 is formed to project conically from the back surface 1b of the light guide plate 1 as shown in the figure.
While the tip has a spherical shape with a radius r, the apex angle θ is 110
It is formed so as to be in the range of ° to 150 °. By forming the protrusion 6 in this manner, light that is incident on the back surface 1b at a critical angle β or more and that should be totally reflected on the back surface 1b surface is reflected on the reflection inclined surface 6a of the protrusion portion 6. The light is totally reflected and directed to the light emitting side surface 1a.
Is set to be equal to or less than the critical angle β so that light can be emitted from the light emitting side surface 1a. Also, the inclined surface of the projection 6 is roughened as shown to scatter incident light and then directed as shown by the broken line,
The protruding portion is hardly seen from the light emitting side surface 1a side.

The lateral pitch Pw is gradually increased as the projection 6 formed as described above is separated from the light source 4 as described above.
The vertical pitch Pd and the vertical pitch Pd are arranged in a dense state, and the arrangement is made so as to be staggered as much as possible, so that the light from the light source 4 can surely reach the opposite surface 1c.

Various experiments were conducted on the apex angle θ of the protrusion, and it was confirmed that the efficiency was the best around 120 °. The height h of the protrusion 6 was 0.05 mm, and the diameter d was 0.25 mm.
Then, good results could be obtained by narrowing the horizontal pitch Pw and the vertical pitch Pd to 0.3 mm in the portion where the protrusions 6 are provided at the highest density and close to the opposite surface 1c.

Next, FIG. 4 is a schematic diagram showing a manufacturing process of a light guide plate mold injection-molded as described above.
(A) immediately after the start, (b) a rough surface processing step, and (c) a mirror surface processing step. FIG. 5 is a schematic diagram showing a manufacturing process of a light guide plate mold, where FIG. 5A shows a mold assembled state, and FIG. 5B shows a state after molding. FIG.

First, in FIG. 4A, a material 1 having a smooth surface 103 forming a surface to be the back surface 1b of the light guide plate 1 is shown.
01a is fixed on the table of the automatic machine 200. After that, the cutting tool 3 having the apex angle θ at the tip end portion of the mold recess 102 serving as a cavity for molding the projection 6
Cutting is sequentially performed by the high-speed rotation drive of 0.

Thereafter, the cutting tool 30 is relatively automatically fed in the vertical Z, front and rear X and left and right Y directions as shown in FIG.
The cutting tool 30 is relatively moved, and the entire mold concave portion 102 is cut by a predetermined cutting feed amount.

In this cutting step, a high-density portion of the mold concave portion 102 for forming the protrusion 6 (a portion where the horizontal pitch Pw and the vertical pitch Pd are, for example, 0.3 mm or less).
Since the shape of the mold concave portion 102 to be machined is likely to be deformed due to the influence of the mold concave portion 102 machined before the cutting process, the cutting process should be performed in order from the mold concave portion 102 farther from the light source 4. Thereby, it is considered that the unavoidable shape distortion generated at the time of processing can be limited to only the side of the reflection slope 6b (FIG. 3B) of the light source in the projection 6.

That is, since the inclined surface 6a contributing to the reflection as described above is processed by the cutting tool 30 at the correct apex angle θ on the surface of the projection 6 farther from the light source 4, the projection 6 In this case, the influence of the reflection of light inside 6 can be minimized.

Next, in FIG. 4B, abrasives having a predetermined particle size are strongly jetted from the sand blast nozzle 300 to the material 101a having the mold concave portion 102 cut as described above to form a smooth surface 103. Both of the mold concave portions 102 are roughened.

Subsequently, as shown in FIG. 4C, the smooth surface 103, which has been roughened by the grinder 301, is ground to remove the irregularities of the rough surface, and then the smooth surface is polished. To a perfect mirror surface. As a result,
A rough surface is formed only on the surface of the mold concave portion 102.

Subsequently, as shown in FIG. 5 (a), the raw material 101a processed as described above is removed from the polishing machine and integrated with the die piece member 101b.
A mold 101 having a cavity C is obtained. This mold member 1
5, as shown in FIG. 5B, the light guide plate 1 is formed by injection molding using an acrylic resin material under predetermined molding conditions.
Get.

Here, when the light sources 4 are provided on both sides of the light guide plate 1 and the light-incident surfaces 1f are provided on both side surfaces, cutting is performed sequentially from the center of the cavity C in the left-right direction. Needless to say. In addition, although the cutting density of the same shape of the mold concave portion 102 is changed by one cutting tool 30, the light source 4 side is shallow and distant with the same cutting tool 30 by changing the cutting depth in a plurality of steps. You may process so that a side may become deep.

The same effect can be obtained by performing similar machining with a plurality of cutting tools having different machining depths or a plurality of different cutting tools having different conical portion areas by changing the radius r of the tip spherical portion. Further, it is possible to change both the density and the depth to greatly change the amount of emitted light without increasing the pitch of the protrusions 6. Can realize a surface light source device having uniform brightness without being noticeable via the diffusion plate 2.

Referring again to FIG. 3B, the reflection slope 6b
Not only does not contribute to the reflection, but also may be an obstacle to ensure that the light L from the light source 4 reaches the reflecting slope 6a. Then, as shown in FIG. 6, the mold concave portion 102 of the mold member 101 is cut so that the cutting tool 30 having the apex angle θ shown by the broken line is inclined toward the light source 4 by the angle B.

According to the projection formed from the mold member obtained in this way, the light L1 and L2 from the light source 4 are not obstructed by the fiber reflection slope 6b, and the reflection slope 6
a, the angle of the reflection slope that increases the light emission component in the vertical direction of the light guide plate can be set, and the brightness can be further increased.

Further, in FIG. 7, the light sources 4 are arranged on both sides of the light guide plate 1 as described above,
When f is provided on both side surfaces, the mold concave portion 102 of the mold member 101 is cut so that the cutting tool 30 having the apex angle θ shown by the broken line is inclined by the angle B. According to the protrusion 6 formed from the mold member 101 obtained in this manner, the light L1 and L2 from the light source 4 can be scattered on the rough inclined surface and then directed to the light emitting surface. Become.

As described above, the mold member for molding the light guide plate 1 is directly cut to form the apex angle of the conical portion of the projection.
The size of the tip r can be freely and efficiently set, and the processing variation of the mold member is small, so that the interval between the projections 6 can be narrowed and the amount of light output from the light guide plate can be increased. As a result, the brightness was increased about 1.5 times that of the conventional chemical etching. In addition, since the mold member is directly cut with a cutting tool, the machining depth of the mold member can be arbitrarily changed, or it can be machined with a plurality of cutting tools. Can be set arbitrarily, and the output light amount can be set large.

The light guide plate 1 is used for a liquid crystal backlight for a portable telephone, 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. 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.

Next, FIG. 7 shows a state in which the mold concave portion 102 serving as a cavity for molding the projection 6 is cut, and the tip apex angle θ is formed at the tip edge of the tip as shown in the figure. The cutting tool 30 is set at an angle B as shown in the figure.
All the recesses 10 are rotated by being rotated in the state of being inclined by a small amount so that the mold recesses 102 serving as the cavities for the projections 6 are gradually fed and cut at the time of resin injection molding.
Process 2 Incidentally, the tip apex angle θ can be adopted from 100 degrees to 150 degrees, and 130 degrees is the best.

By using the cutting tool 30 having the cutting edge formed as described above, it is possible to perform machining with an arbitrary inclination angle. From this state, the cutting tool 30 is cut by a predetermined cutting feed amount while the cutting tool 30 is relatively automatically fed in the front-rear X direction as shown in the drawing and perpendicular to the light incident side surface 1f. In this way, a cavity for a protruding portion, which will be described later, can be formed.

Further, the cutting tool 30 is rotated and driven so as to gradually change the inclination angle B of the cutting tool 30 to change the inclination angle of the inclined surface of the mold concave portion 102 serving as a cavity for the projection 6 during resin injection molding. It is also possible.

FIG. 8 is a cross-sectional view of an apparatus including the light guide plate 1 injection-molded from a mold obtained by using the cutting tool 30 described in FIG. In the figure, the components already described are given the same reference numerals, and the description thereof will be omitted. The characteristic portion will be described. The protrusion 6 has a conical shape.
The light guide plate 1 has an inclined surface having an inclination angle γ that is normal to the back surface 1b. The inclination angle γ of the inclined surface is the inclination angle γ1 near the light incident side surface 1f of the light guide plate 1, and
The inclination angle γn is near the opposite surface 1c of the light guide plate 1, and is formed so that the inclination angle γ gradually decreases.

As described above, by making the inclination angles γ different from each other, incident light incident at a critical angle β or less determined from the resin material is irregularly reflected on the inclined surface of the projection 6 as described above. Thus, a uniform light amount is obtained over the entire light guide plate 1.

In FIG. 8, the height of each projection 6 is h1 near the light incident side surface 1f of the light guide plate 1, and becomes h near the opposite surface 1c of the light guide plate 1. The height h is gradually reduced.

As described above, by making the heights h of the projections 6 different from each other, the incident light incident at a critical angle β or less determined from the resin material as described above is irregularly reflected on the inclined surface of the projections 6. In this way, a uniform light amount is obtained over the entire light guide plate 1.

Next, FIG. 9 is a plan view of a light guide plate 1 according to another embodiment of the oval shape viewed from the back surface 1b side.

In this figure, the projection 6 is an elliptical shape in which the longitudinal direction is arranged substantially parallel to the light source 4 as shown in the figure. Then, in a portion close to the light source 4, the horizontal pitch Pw
And the vertical pitch Pd is arranged in a sparse state,
As the distance from the light source 4 increases, the horizontal pitch Pw and the vertical pitch Pd gradually become denser.
By arranging as staggered as possible as shown,
The projections 6 are arranged based on a simulation analysis of a computer so that the light from the light source 4 can reach the adjacent projections 6 reliably.

FIG. 10A is a front view showing the shape of the projection 6 shown in FIG. 9, and FIG.
10A is a cross-sectional view taken along the line AA, and FIG.
FIG. 3A is a cross-sectional view taken along line BB of FIG.

In this figure, the base of the projection 6 has an oblong shape whose dimension along the normal to the light incident side surface 1f shown in FIG. 1 is larger than the dimension along the width direction of the light guide member 1. An inclined surface is formed at an inclination angle from the base. As shown in FIGS. 10 (b) and 10 (c), each of the inclined surfaces 6 has an inclination angle of γ with respect to the normal from the back surface of the light guide member 1.
a, 6b, 6c, and 6d. The top 6k of the projection 6 is formed as shown. In order to form such a shape, the cutting described with reference to FIG. 7 is preferably employed. Note that the angle γ was best at 45 degrees.

In the projection 6 formed as described above, the incident light which is incident at the critical angle β or less is first applied to the top 6.
After reflecting at k, the inclined surfaces 6a, 6b, 6c, 6d
, And diffusely reflected light L1, L2, L3, L4
As a result, the light is directed to the diffusion plate 5, so that the overall brightness can be increased.

According to the above embodiment, the case of the protrusions 6 having the same shape has been described. However, the present invention is not limited to this.
The height of the top 6k of the projection 6 may gradually increase as the distance from the light source increases. Further, by changing the taper angle of the cutting edge of the cutting tool 30, the inclined surface 6
The area of the conical portion formed by a and 6b may be changed. As the rough surface processing method, various types of processing can be performed in addition to the above sand blasting method. For example, there is an etching method for forming a grain which is performed after die processing.

[0064]

【The invention's effect】

As described above, according to the present invention, the projection formed on the light guide plate is accurately formed, and the directivity of the light reflected on the inclined surface of the projection toward the light emitting surface is enhanced. In addition, a method for manufacturing a light guide member capable of preventing projections from appearing in a dot state from the light emitting surface side, enabling the use of a diffusion plate having a low diffusivity, and increasing luminance of the entire surface light emitting device. And a surface light emitting device using the light guide member.

[Brief description of the drawings]

1A is a cross-sectional view of a surface light emitting device, and FIG. 1B is a partially enlarged cross-sectional view of a light guide plate.

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; FIG. 2B is a cross-sectional view of a main part showing a state of reflection of light L on the protrusion 6.

FIGS. 4A and 4B are schematic diagrams showing a manufacturing process of a light guide plate mold, in which FIG. 4A is immediately after starting, FIG. 4B is a rough surface processing step, and FIG.
Indicates a mirror finishing step.

FIG. 5A is a schematic diagram illustrating a state in which a mold is assembled, and FIG. 5B is a schematic diagram illustrating a state after molding.

FIG. 6 is a view showing a cutting process of a mold for a light guide plate.

FIG. 7 is a cutting diagram of a mold for a light guide plate.

FIG. 8 is a cross-sectional view of the surface light emitting device.

FIG. 9 is a plan view of the back surface of the light guide plate.

FIG. 10A is a plan view showing the shape of a projection,
(B) is a sectional view taken along arrow AA, and (c) is a sectional view taken along arrow BB.

FIG. 11A 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, 1 f light incident side surface 2 diffuser plate, 3 reflection frame, 4 light source, 5 substrate 6 protrusion, 6 a, 6 b, 6 c, 6 d inclined surface, 6 k top, 30 cutting tool, 101 type member, 102 type concave portion, β critical angle

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masafumi Ono 2-16-20 Shimura, Itabashi-ku, Tokyo Inside Copal Corporation

Claims (5)

[Claims] 1. A light source is disposed on a side or both sides of a light-transmitting plate-shaped light guide member, and guides light from the light source from a light incident surface of the light guide member to the inside. In order to illuminate by scattering light with a diffusion member arranged in parallel with the light emitting surface of the light guide member, countless protrusions are formed on the back surface of the light emission surface of the light guide member, and the brightness of the diffusion member is reduced over the entire surface. A method of manufacturing a light guide member for uniformity over, a mold member for molding the protrusion and the back surface,
A material having a smooth surface is sequentially cut with a cutting tool having an apex angle θ to form a concave portion having an inclined surface, and the smooth surface and the concave portion are formed to a predetermined roughness by a rough surface processing method including a sand blast method. Processing into a rough surface, Next, by using the mold member having only the smooth surface as a mirror surface by a mirror finishing method including polishing, injection molding from a light-transmitting resin material, A method for manufacturing a light guide member, wherein incident light incident at a determined critical angle β or more is diffused on the inclined surface toward the light emitting surface. 2. A light source is disposed on a side or both sides of a light-transmitting plate-shaped light guide member, and guides light from the light source from a light incident surface of the light guide member to the inside. In order to scatter and illuminate light with a diffusion member arranged in parallel with the light emitting surface of the light guide member, countless protrusions are formed on the back surface of the light emission surface of the light guide member, and the brightness of the diffusion member is reduced. A surface light emitting device using a light guide member that makes the light guide member uniform over the entire surface, wherein the protrusion has an inclination angle γ that is normal to the back surface of the light guide member and includes a sloped surface that is formed as a rough surface. In addition, a surface light emitting device using a light guide member having the rear surface formed into a mirror surface and diffusing incident light incident at a critical angle β or more determined from the resin material toward the light emitting surface on the inclined surface. 3. The projection portion has a conical shape in which the inclined surface is continuously formed, or a first portion along a normal line of the light incident surface.
Is larger than a second dimension along the width direction of the light guide member, the inclined surface extending from the oblong base with an inclination angle γ, and continuous from the inclined surface. The surface light emitting device using the light guide member according to claim 2, wherein the light emitting member is formed in a substantially elongated conical shape that is formed from a top portion substantially parallel to the oval base portion. 4. The light guide member according to claim 2, wherein the protrusions are formed with a high density substantially proportional to a distance from the light incident surface. Surface emitting device. 5. The method according to claim 2, wherein a height of the projection from the rear surface is gradually increased substantially in proportion to a distance from the light incident surface. A surface light emitting device using the light guide member according to any one of the preceding claims.