JPH0668563B2 - Light guide for surface light source conversion - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a light guide for surface light source conversion, and more particularly to a surface light source conversion capable of forming a surface light source using a point light source or a line light source. The present invention relates to a light guide for a vehicle.

More specifically, the light emitted from a point light source or a line light source is diffused from a large number of reflection portions or refraction portions to form a large number of point or linear light sources, and a surface light source as a whole. The present invention relates to a light guide for surface light source conversion that can be performed.

(Prior Art) In recent years, a liquid crystal display device (hereinafter, referred to as LCD) has been widely used as a display device of various display devices.

As is well known, since this LCD is not a self-luminous device, it is necessary to somehow prepare a light source (backlight) for illumination in order to use the LCD in a dark place.

Therefore, in the conventional LCD, it is necessary to dispose a light source behind the LCD or to dispose a reflector behind the LCD and dispose the light source in front of it.

(Problems to be Solved by the Invention) The above-described conventional technique has the following problems.

Since the light source is a line light source or a point light source, it cannot uniformly illuminate the entire LCD. As a result, LC
There is a problem that the display content of D becomes extremely difficult to see and the commercial value of the LCD is reduced.

Further, when a plurality of line light sources or point light sources are provided, or a Fresnel lens or the like is provided to approximately obtain a surface light source, the manufacturing cost of the light source increases or the LCD is used. There is also a problem in that the thickness of the existing display device is increased particularly.

The present invention has been made to solve the above problems.

(Means and Actions for Solving Problems) In order to solve the above problems, the present invention provides a transparent and plate-shaped light propagating member, and the light propagating member is disposed on both sides of the light propagating member. Light propagating means is constituted by the first and second reflecting members that reflect the light propagating inside the propagating member into the light propagating member, and the light emitted from the point light source or the line light source is the light propagating member. A plurality of reflection parts or refraction parts are formed in the light propagation means so that at least a part of the light is propagated in a plane from the light propagation means by a large number of point light sources or line light sources. It is a means to do.

Then, as a result, the point that the surface light source can be configured by using the point light source or the line light source is characteristic.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

2 is a schematic perspective view of the first embodiment of the present invention, FIG. 3 is a plan view of FIG. 2, and FIG. 4 is a schematic sectional view of FIG. 2 taken along the line C--C. FIG. 4 is an enlarged view of the surface light source conversion light guide body 10 shown in FIG. 4.

In addition, in FIGS. 2 and 3, in order to make the figures easy to see,
The light collector 5 is omitted.

In each drawing, the first reflecting member 2 and the second reflecting member 3 (cladding layer) are each made of a transparent material having a relatively small refractive index. The light propagating member 1 (core layer) is also a transparent member, but its material is selected so as to have a larger refractive index than those of the first reflecting member 2 and the second reflecting member 3.

The first reflecting member 2 and the second reflecting member 3 are fixed to the surfaces on both sides of the light propagating member 1, respectively. The light propagating member 1, the first reflecting member 2, and the second reflecting member 3 form a surface light source conversion light guide 10.

A linear light source 4 is arranged on the side surface of the surface light source conversion light guide 10. A light condensing plate 5 is arranged around the linear light source 4 so that the light emitted from the linear light source 4 is efficiently incident on the side surface of the light propagating member 1 into the light propagating member 1. There is.

The first reflecting member 2 is provided with a plurality of slits 2A substantially parallel to the linear light source 4. The slit 2A is formed so that the light propagating member 1 is exposed and the exposed surface 9 of the light propagating member 1 can obtain a light diffusion effect.

Further, as is clear from FIG. 3, the pitch P between the slits 2A is set so as to become narrower as the distance from the linear light source 4 increases. From this slit 2A,
As will be described later with reference to FIG. 5, light emitted from the linear light source 4 and propagating in the light propagating member 1 leaks. That is, each of the slits 2A acts as a linear light source.

FIG. 5 shows that the light propagating in the light propagating member 1 has slits 2A.
It is a figure for demonstrating a mode that it leaks from, and is a figure similar to FIG. 5, the same reference numerals as those in FIG. 1 represent the same or equivalent portions. Note that, in FIG. 5, hatching showing a cross section is omitted in order to make the drawing easy to see.

In FIG. 5, light emitted from the light source in the direction of arrow A enters the light propagating member 1.

When the light propagating in the light propagating member 1 reaches the exposed surface 9,
As shown by the arrow B in FIG. 5, the light diffuses and leaks to the slit 2A. The light leaking into the slit 2A proceeds to the outside of the surface light source conversion light guide 10 as shown in the drawing.

That is, in the first embodiment of the present invention, the linear light source 4
By turning on, the exposed surface 9 of the light propagating member 1 corresponding to the slit 2A formed in the first reflecting member 2 emits light.

In this case, the amount of light emitted from the exposed surface 9 is
Is reduced as the distance from the linear light source 4 is increased, but as described above, the pitch P between the slits 2A is set to be narrower as the distance from the linear light source 4 is increased. The amount of light emitted can be made macroscopically uniform.

In the first embodiment of the present invention described above, the light propagating in the light propagating member 1 due to the light emission of the line light source 4 is emitted from the line light source 4 among the side surfaces of the surface light source conversion light guide 10. Since there is a risk of leakage from three side surfaces (L1, L2, and L3 shown in FIG. 3) that do not face each other, a member capable of reflecting light into the light propagation member 1 is arranged on the side surface, Alternatively, a reflective paint may be applied.

Further, although the slit 2A has been described as being formed in the first reflecting member 2, the slit 2A is not particularly limited to this, and may be formed in the second reflecting member 3, or may be formed. It may be formed on both the first reflecting member 2 and the second reflecting member 3.

When the slits 2A are formed in both the first reflecting member 2 and the second reflecting member 3, light is emitted from both surfaces of the surface light source conversion light guide 10.

In addition, the first reflecting member 2 and the second reflecting member 3
Has been described as a transparent member having a smaller refractive index than the light propagating member 1, but may be a mirror-like member whose surface facing the light propagating member 1 is a reflecting surface.

Further, in order to make the light emitted from the surface light source conversion light guide 10 substantially uniform, the slit 2A is formed so that its pitch becomes narrower as the distance from the linear light source 4 increases. The pitches may be made equal and the width of each slit 2A may be made wider as the distance from the linear light source 4 increases.

Furthermore, the slit 2A has been described as being formed so as to be substantially parallel to the linear light source 4, that is, substantially perpendicular to the propagation direction of the light propagating in the light propagating member 1. In the first embodiment, since the light leaks from the exposed surface 9 of the light propagating member 1, the slit 2
Naturally, A may be formed so as to be parallel to the propagation direction of the light propagating in the light propagating member 1. In this case, since the amount of light leaking from the slit 2A decreases as the distance from the linear light source 4 increases, the width of the slit 2A is set to be substantially uniform in order to make the light emitted from the surface light source conversion light guide 10 substantially uniform. The slits 2 </ b> A may be increased as the distance from the linear light source 4 is increased or the distance from the linear light source 4 is increased.

Further, although the slit 2A has been described as having a strip shape, it may be a simple hole.

Next, another modification of the first embodiment will be described with reference to the second to sixth embodiments.

FIG. 6 is a schematic plan view of the second embodiment of the present invention.

The light source 44 shown in FIG. 6 is a point light source unlike the linear light source 4 shown in the first embodiment. The point light source 44 is a predetermined cutout 2 of the surface light source conversion light guide 20.
It is located at 0A.

The first reflecting member 12 is provided with a plurality of arcuate slits 2A centered on the light emitting portion of the point light source 44. The pitch between the slits 2A is set to become narrower as the distance from the point light source 44 increases.

Thus, in the present invention, the surface of the first reflecting member of the surface light source conversion light guide can be made to emit light not only by using the line light source but also by using the point light source.

FIG. 7 is a schematic sectional view of a third embodiment of the present invention, which is similar to FIG. In FIG. 7, the same reference numerals as those in FIG. 4 represent the same or equivalent parts.

The third embodiment of the present invention shown in FIG. 7 is, as is clear from comparison with FIG. 4, a surface light source conversion light guide 30.
The side surface facing the linear light source 4 is formed at an acute angle with respect to the surface of the second reflecting member 3.

As a result, the portion 1 of the light propagation member 1 facing the linear light source 4
Since the area of A becomes larger than that of the first embodiment shown in FIG. 4, the amount of light incident on the light propagating member 1 increases, and the slit 2A, that is, the exposed surface 9 of the light propagating member 1 The amount of light emitted increases.

The side surface of the surface light source conversion light guide 30 facing the linear light source 4 may be formed at an acute angle with respect to the surface of the first reflecting member 2.

FIG. 8 is a schematic plan view of the fourth embodiment of the present invention and is similar to FIG. In FIG. 8, the same symbols as those in FIG. 3 represent the same or equivalent portions.

The fourth embodiment of the present invention shown in FIG. 8 is, as is clear from comparison with FIG. 3, a surface light source conversion light guide 40.
The line light sources 4 and 34 are arranged on two of the four side surfaces (two side surfaces adjacent to each other in this example).

Further, the linear light sources 4 and 34 are provided on the first reflecting member 32.
Slits 2A so that they are parallel to
Are formed, and the pitch between the slits 2A is set to become narrower as the distance from the linear light sources 4 and 34 increases.

In the fourth embodiment of the present invention having the above configuration, when the light quantity of the linear light source 34 is substantially equal to the light quantity of the linear light source 4,
The amount of light emitted from the first reflecting member 32 of the surface light source conversion light guide 40 is about twice as large as when only the linear light source indicated by reference numeral 4 is used as the linear light source.

In the fourth embodiment, the linear light sources are described as being arranged adjacent to each other on two sides of the rectangular light propagating member, but the present invention is not limited to this. Instead, they may be arranged so as to face each other.
Further, three or more light sources may be arranged.

In addition, even when the planar contour shape of the surface light source conversion light guide 40 is a shape other than a rectangle as shown in FIG. 8, that is, a shape such as a triangle, a pentagon, or a circle,
Multiple light sources can be arranged as described with respect to this fourth embodiment.

Furthermore, although the light source has been described as being a line light source, it goes without saying that it may be a point light source as described with respect to the second embodiment (FIG. 6).

FIG. 9 is a schematic sectional view of a fifth embodiment of the present invention and is similar to FIGS. 4 and 7. In FIG. 9, the fourth and seventh
The same reference numerals as those in the drawings represent the same or equivalent parts.

The surface light source conversion light guide 50 shown in FIG. 9 is the same as the surface light source conversion light guide 10 shown in FIG.

In this case, as shown in FIG. 9, the slit 2A formed in the one first reflecting member 2 is arranged between the slits 2A formed in the other first reflecting member 2. By doing so, since the arrangement density of the slits 2A is substantially increased, it is possible to increase the amount of light emitted from the surface light source conversion light guide 50 and also to improve the uniformity of light. . Alternatively, three or more surface light source conversion light guides may be stacked.

FIG. 10 is a schematic sectional view of a sixth embodiment of the present invention,
It is a figure similar to FIG. 10, the same reference numerals as those in FIG. 1 represent the same or equivalent parts.

In FIG. 10, the second reflecting member 53 is a member that constitutes a part of another device (not shown), and may be made of any material, but the surface thereof is the first reflecting member 2. In the same manner as above, it is coated with a material that is transparent and has a smaller refractive index than the light propagation member 1. Further, the surface of the second reflecting member 53 may be mirror-finished so that light is reflected.

The first reflecting member 2 is provided on the surface of the second reflecting member 53.
The light propagation member 1 to which is fixed is arranged. Then, a slit 2A is formed in the first reflecting member 2.

Also in the sixth embodiment of the present invention having the above configuration,
By irradiating the side surface of the surface light source conversion light guide 60, that is, the side surface of the light propagating member 1 with light so that the light travels in a direction perpendicular to the slit 2A (direction of arrow A),
The light propagates in the light propagating member 1 as in the first to fifth embodiments and is emitted from each exposed surface 9.

Next, a surface light source conversion light guide having a slit having a configuration different from that of the slit 2A in the first to sixth embodiments will be described.

FIG. 12 is a schematic perspective view of a seventh embodiment of the present invention, a thirteenth embodiment.
The figure is a schematic cross-sectional view taken along line GG in FIG.
The figure is an enlarged view of the light guide 70 for surface light source conversion shown in FIG.

Incidentally, in FIG. 12, as in FIG. 2, the light collector 5 is omitted for the sake of easy understanding of the drawing.

The light propagating member 1, the first reflecting member 2 and the second reflecting member 3 in FIGS. 11 to 13 are transparent members, and are the same as those in the first embodiment. The refractive index is larger than that of the first reflecting member 2 and the second reflecting member 3.

The slit 3A of the surface light source conversion light guide 70 is formed at a position different from the formation position of the slit 2A of the surface light source conversion light guides 10 to 60 shown in the first to sixth embodiments. .

That is, the slits 2A of the surface light source converting light guides 10 to 60 are formed in the first reflecting member 2 arranged on the light emitting direction side of the reflecting members arranged on both sides of the light propagating member 1. On the other hand, the slit 3A of the surface light source conversion light guide 70 in the seventh embodiment is formed in the second reflecting member 3 on the side opposite to the light emitting direction.

The cross section of the slit 3A is formed so as to have a predetermined inclination with respect to the average propagation direction of light propagating in the light propagation member 1 (direction of arrow A in FIG. 11).

Further, the slit 3A further includes the second reflecting member 3
In addition, it is formed so as to reach the inside of the light propagating member 1 from the second reflecting member 3.

The slit 3A is substantially parallel to the line light source 4 arranged on the end face of the surface light source conversion light guide 70 and the pitch thereof is the same as that of the slit 2A in the first embodiment. It is formed so that it becomes smaller as it gets farther from the light source 4.

FIG. 14 is a diagram for explaining how the light propagating in the light propagating member 1 of the surface light source conversion light guide 70 leaks from the surface of the first reflecting member 2 to the outside, and FIG. It is a figure similar to. 14, the same reference numerals as those in FIG. 11 represent the same or equivalent portions. Note that, in FIG. 14, hatching showing a cross section is omitted in order to make the drawing easy to see.

In FIG. 14, the light emitted to the light propagating member 1 from the direction approximately indicated by the arrow A is the same as the light propagating member 1
The light propagates in the light propagation member 1 while being reflected by the boundary surface between the reflection member 2 and the second reflection member 3.

Here, when a part of the light reaches the slit 3A formed in the light propagating member 1, a part of the light reaching the slit 3A is reflected by the slit 3A (arrow D direction), and the rest thereof. Passes through the slit 3A. That is, the slit 3A formed in the light propagation member 1 has a half-mirror-like effect.

Therefore, the light reflected by the slit 3A in the direction of the arrow D is the boundary surface between the light propagating member 1 and the first reflecting member 2,
Further, if the angle θ of the slit 3A with respect to the light propagation direction A is set so that the light is incident on the surface of the first reflecting member 2 at a required angle of incidence, the slit 3A indicates an arrow D.
The light reflected in the direction exits the surface light source conversion light guide 70 from the first reflecting member 2.

As described above, the amount of light reflected by the slit 3A and passing out of the surface light source conversion light guide 70 becomes smaller as the position of the reflected slit 3A moves away from the light source (the linear light source 4 in FIG. 12). As described above, the slits 3A are formed such that the pitch P thereof becomes smaller as the distance from the linear light source 4 increases, so that a substantially uniform amount of light is obtained from the surface of the first reflecting member 2. be able to.

In addition, in FIG. 12, the slit 3A is a linear light source 4
However, this embodiment is not particularly limited to this, and a plurality of needle hole-shaped holes may be formed.

Also in the seventh embodiment, similarly to the modification of the first embodiment, a point light source is used as the light source, and the slit 3A is formed in an arc shape with the light source at the center (see FIG.
Example), the light incident portion of the surface light source conversion light guide, that is, the portion facing the linear light source 4 is formed at an acute angle to increase the amount of light incident into the light propagating member 1 (first embodiment). 7), a plurality of light sources are arranged and the slit 3 is formed.
A is formed so as to be perpendicular to the light emitted from each light source to increase the amount of light (fourth embodiment of FIG. 8), or a plurality of surface light source conversion light guides are stacked. The amount of light may be increased (fifth embodiment of FIG. 9).

Further, the second reflecting member 3 is a transparent member having a smaller refractive index than the light propagating member 1 like the first reflecting member 2, but may be a means such as a mirror.

Furthermore, when both the first reflecting member 2 and the second reflecting member 3 are transparent members, the slits 3A may be formed on both the second reflecting member 3 side and the first reflecting member 2 side. good. As a result, the light propagating in the light propagating member 1 is emitted from the surfaces on both sides of the surface light source conversion light guide 80.

Furthermore, although the slit 3A has been described as being formed so as to reach the inside of the light propagating member 1 from the surface of the second reflecting member 3, it may be formed only in the light propagating member 1.
That is, when the slit 3A is formed after fixing the light propagating member 1 and the second reflecting member 3, the second member is inevitably used.
Although a slit is also formed in the reflecting member 3 of the above, if the slit is formed before the step of fixing the light propagating member 1 and the second reflecting member 3, the slit is formed only in the light propagating member 1. Can be done.

FIG. 15 is a schematic sectional view showing an eighth embodiment of the present invention and is similar to FIG. The eighth embodiment is another modification of the seventh embodiment. First
5, the same reference numerals as those in FIG. 14 represent the same or equivalent portions.

As is clear from FIG. 15, the pitch P between the slits is
It is constant irrespective of the distance from the light source (not shown), but the notch of the slit with respect to the light propagating member 1 becomes deeper as the distance from the light source increases.

As a result, the area of the reflecting surface of the slit for reflecting the light propagating in the light propagating member 1 to the outside of the surface light source conversion light guide 80, that is, the area of the slit formed in the light propagating member 1 is The slit 3C on the side far from the light source is larger than the slit 3B on the side close to the light source.

Therefore, also in the eighth embodiment, as in the case of the seventh embodiment, it is possible to obtain a substantially uniform amount of light from the surface of the first reflecting member 2.

FIG. 16 is a schematic sectional view showing a ninth embodiment of the present invention and is similar to FIG. The ninth embodiment is another modification of the seventh embodiment. First
6, the same reference numerals as those in FIG. 11 represent the same or equivalent portions.

In FIG. 16, the second reflecting member 93 is a member forming a part of another device not shown, like the second reflecting member 53 shown in FIG. Although it may be formed, its surface is coated with a material that is transparent and has a smaller refractive index than that of the light propagation member 1, like the first reflecting member 2. Further, the second reflecting member 93 may be mirror-finished so that the surface thereof reflects light.

On the surface of the second reflecting member 93, the light propagating member 1 having the slit 93A is fixed so that the side having the slit 93A is in contact with the second reflecting member 93, and further, The first reflecting member 2 is fixed to the light propagating member 1.

Also in the ninth embodiment having such a configuration, when light is emitted from the side surface of the surface light source conversion light guide 90 in the direction of arrow A, the light propagates in the light propagation member 1 and the light Is partially reflected by each slit 93A, and the first reflecting member 2
Emitted from the surface of.

Instead of forming the slit 93A on the light propagating member 1, a reflecting member corresponding to the slit 93A is formed on the second reflecting member 93, and the light propagating member 1 is secondly formed by vapor deposition or the like. It may be fixed and formed on the reflecting member 93.

FIG. 17 is a schematic sectional view showing a tenth embodiment of the present invention, and like FIG. 15, is not hatched for the sake of clarity. The embodiment shown in FIG. 10 is a modification of the eighth embodiment shown in FIG. First
7, the same reference numerals as those in FIG. 15 represent the same or equivalent parts.

In FIG. 17, the slit 2B of the surface light source conversion light guide 100 is similar to the slit 3B shown in FIG.
It is formed at a predetermined angle with respect to the average traveling direction A of the light propagating in the light propagating member 1, and its formation is different from the surface on which the slit 3B shown in FIG. 15 is formed. This is performed from the opposite surface, that is, the surface of the surface light source conversion light guide 100 on the side on which the first reflecting member 2 is arranged, where the light is reflected by the slits 2B.

Also in the tenth embodiment, the surface light source conversion light guide 1
The light incident from the side surface of No. 00 can be radiated from the surface of the first reflecting member 2 almost uniformly.

In FIG. 17, although the pitch between the slits 2B is constant regardless of the distance from the light source (not shown), as the distance from the light source increases, the slits 2B
Although the depth of cut in the light propagating member 1 is deep, the depth of the slits 2B is constant regardless of the distance from the light source and the pitch between the slits 2B is the same as in the example shown in FIG. Of course, the distance may be narrowed as the distance from the light source increases.

Now, the present inventor made a prototype of the light guide for surface light source conversion shown in each of the above-mentioned embodiments, and confirmed its optical characteristics. As the light propagating member 1 of the light guide for surface light source conversion, 0.73
For the [mm] thick polymethylmethacrylate (PMMA) sheet, and for the first reflecting member 2 and the second reflecting member 3, 0.01 [mm] thick fluororesin was used. Both the PMMA sheet and the fluororesin have flexibility.

As a result of various experiments, as shown in the first to sixth embodiments (FIGS. 1 to 10), the slit 2A was formed so as to expose the surface of the light propagating member 1 and the exposed surface. Is formed to have a certain width so as to have a light diffusing effect, and the surface light source conversion light guide body is configured so that light is emitted from the first reflecting member 2. Or first
No. 0 (FIGS. 11 to 17), the slit is cut into the inside of the light propagating member 1, and the cut portion is an average of light propagating in the light propagating member 1. Is formed so as to be inclined at a predetermined angle with respect to the general traveling direction A, the light propagating in the light propagating member 1 is reflected at the cut portion, and the light is emitted from the first reflecting member 2. It was confirmed that the light amount of the radiated light increased when the light guide for surface light source conversion was configured as described above.

Further, in the seventh to ninth embodiments, the angle between the slit and the light propagation direction A--that is, if the thickness of the second reflecting member 3 is constant, the slit and the second Angle θ formed by the reflection member 3 (Figs. 14 and 15)
However, it was also confirmed that the amount of light emitted from the first reflecting member 2 increases when the angle is in the range of 30 degrees to 60 degrees (preferably 45 degrees).

In FIGS. 11 and 14 to 17, the slits 3A, 3B, 3C, 93A and 2B are drawn so as to have a certain width, but they may be mere cuts.

Further, in all of the above-described embodiments, a light diffusing element such as frosted glass may be arranged on the surface of the first reflecting member 2 in order to make the light emitted from the first reflecting member 2 uniform. . Further, instead of disposing the light diffusing element, a light diffusing treatment may be performed on the surface of the first reflecting member 2.

Furthermore, by expanding the technical idea of each of the above-described embodiments and arranging the optical fibers densely on a plate and providing slits in the optical fibers, the same configuration as that of each of the above-described embodiments is obtained. be able to. In this case, the light guide may be formed by winding the optical fiber in a spiral shape.

Further, as described above, by configuring the surface light source conversion light guide body with a flexible material, it is possible to radiate light propagating in the light propagation member 1 from an arbitrary curved surface.

It should be noted that the present invention is not limited to the application as a backlight for an LCD, and may be applied to various light sources such as a backlight for various display panels or a simple light source for illumination.
It goes without saying that it can be applied to a device.

Further, the slit does not have to be formed over the entire surface of the light propagating member or the reflecting member, and it is needless to say that the slit may be formed only in a part thereof so that a light emitting surface having an arbitrary shape can be obtained. .

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects are achieved.

(1) Since the slits are provided in the light propagating member including the light propagating member and the reflecting members formed on both surfaces of the light propagating member, the light emitted from the point light source or the line light source can be approximated to an arbitrary shape. Can be emitted from the plane.

(2) As a result, in a display device having an LCD, for example, when the surface light source conversion light guide having a light source arranged on its side surface is arranged behind the LCD as a light source for the backlight of the LCD, at least the LCD is provided. It is possible to reduce the thickness of the display device in the portion where is arranged.

[Brief description of drawings]

FIG. 1 is an enlarged view of the light guide for surface light source conversion shown in FIG. 4, FIG. 2 is a schematic perspective view of the first embodiment of the present invention, and FIG.
FIG. 4 is a plan view of FIG. 2, FIG. 4 is a schematic sectional view of FIG. 2 taken along the line C-C, and FIG. 5 is light propagating in the light propagating member leaking from the light guide for surface light source conversion. To explain the situation,
FIG. 4 is an enlarged view of the light guide for surface light source conversion shown in FIG. 4, FIG. 6 is a schematic plan view of a second embodiment of the present invention, and FIG. 7 is a schematic cross section of a third embodiment of the present invention. FIG. 8 is a schematic plan view of a fourth embodiment of the present invention, FIG. 9 is a schematic sectional view of a fifth embodiment of the present invention, and FIG. 10 is a schematic view of a sixth embodiment of the present invention. FIG. 11 is a sectional view, FIG. 11 is an enlarged view of the surface light source conversion light guide shown in FIG. 13, FIG. 12 is a schematic perspective view of a seventh embodiment of the present invention, and FIG. FIG. 14 is a schematic cross-sectional view taken along line GG, FIG. 14 is a surface light source conversion shown in FIG. 13 for explaining how light propagating in the light propagating member leaks from the surface light source conversion light guide. FIG. 15 is an enlarged view of a light guide for use in the invention, FIG. 15 is a schematic sectional view showing an eighth embodiment of the present invention, FIG. 16 is a schematic sectional view showing a ninth embodiment of the present invention, and FIG. Tenth Example of Is a schematic cross-sectional view illustrating. 1 ... Light propagating member, 2, 12, 32 ... First reflecting member, 2A, 2B, 3A, 3B, 3C, 93A ... Slit, 3, 53, 93 ... Second reflecting member, 4, 34 ……
Linear light source 10, 20, 30, 40, 50, 60, 70,
80, 90, 100 ... Light guide for surface light source conversion, 44 ...
Point light source

Claims (4)

[Claims] 1. A transparent and plate-shaped light propagating member, which is disposed on one surface of the light propagating member, is transparent, has a refractive index smaller than that of the light propagating member, and has a light-transmitting surface. A first reflection member that has been subjected to a diffusion treatment, a second reflection member that is disposed on the other surface of the light propagation member, is transparent, and has a smaller refractive index than the light propagation member, and at least the light propagation member And a slit that is a large number of thin groove-shaped notches formed, the slit reflects a part of the light propagating in the light propagating member on its surface, and the slit and the light propagating member The boundary surface with the reflecting member is entirely inclined so that light is incident at an incident angle required to leak from the first reflecting member to the outside, and the area of the slit per unit surface area of the light propagating member. It is formed so that the rate becomes smaller as it approaches the light source. A light guide for converting a surface light source, which is characterized in that 2. The surface light source conversion light guide according to claim 1, wherein the slit penetrates at least one of the first and second reflecting members. 3. The surface light source conversion light guide according to claim 1 or 2, wherein a side surface facing the light source is inclined. 4. A light guide for surface light source conversion, wherein a plurality of light guides for surface light source conversion according to any one of claims 1 to 3 are stacked.