JPH11231320A - Side light type planar light source unit and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the quantity of outgoing light uniform by making the illumination light emitted from a light source incident through an end surface of a rod-like member and emitting the light from a surface along the flank of a planar member formed by repeating a projection consisting of a couple of oblique surfaces in the longitudinal direction. SOLUTION: A light guide plate 11 is formed into a tip-truncated wedgewise sectioned shape by molding, for example, an acrylic resin of a transparent member by injection and the illumination light L1 of a primary light source 12 is made incident from the incident surface 11A. Consequently, the light guide plate 11, while propagating the illumination light L1 made incident from the incident surface 11A into the inside, emits a component of less than the critical angle from a outgoing surface 11B. Further, the light guided plate 11 has projections formed by repeating a couple of oblique surfaces 18A and 18B in the longitudinal direction of the incident surface 11A as shown by a partially enlarged part A of the incident surface 11A. Here, the projections is formed by directly connecting the couple of oblique surfaces 18A and 18B. Then the directivity of the illumination light L1 is corrected to a direction perpendicular to the incident surface 11A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side light type surface light source device and a liquid crystal display device, and more particularly to a linear primary light source formed of illumination light such as a light emitting diode using a rod-like member.
The present invention can be applied to a case where the illumination light emitted from the primary light source is incident on a plate-shaped member formed of a light guide plate to form a surface light source device. According to the present invention, the amount of emitted light is made uniform by repeatedly forming a pair of inclined projections on the incident surface of the plate-shaped member in the longitudinal direction of the incident surface.

[0002]

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

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

In a liquid crystal display device using such a sidelight type surface light source device, it is required that the overall shape be reduced in size and weight.

For this reason, in a side light type surface light source device, as disclosed in, for example, JP-A-9-120007, instead of a fluorescent lamp, illumination light emitted from a point light source such as a lamp is applied to a rod-shaped member. There has been proposed an arrangement in which a primary light source is formed by being incident.

FIG. 24 is an exploded perspective view showing a side light type surface light source device using this point light source. In this sidelight type surface light source device 1, a primary light source 2 is arranged on a side of a light guide plate 3, and illumination light L1 emitted from the primary light source 2 is transmitted from a side surface (hereinafter, referred to as an incident surface) 3A of the light guide plate 3. The light enters the light guide plate 3.

The primary light source 2 is composed of a rod-shaped member 4 extending along the incident surface 3A, and a point light source for irradiating the illumination light L to one end of the rod-shaped member 4. The rod-shaped member 4 is formed, for example, by cutting and polishing a transparent member having a cylindrical shape, so that the cylindrical shape is cut obliquely by a plane, and a reflection surface 4A is formed on the plane side. Accordingly, the rod-shaped member 4 transmits the illumination light incident from the incident surface that is the end face to the other end face while transmitting the illumination light to the light guide plate 3.
Out of the light incident surface 3A.

The light guide plate 3 is formed into a wedge-shaped cross-section by injection molding, for example, acrylic (PMMA resin) made of a transparent member, and receives the illumination light L1 of the primary light source 2 from the incident surface 3A. Thus, the light guide plate 3 emits components smaller than the critical angle from the emission surface 3B while propagating the illumination light L1 incident from the incident surface 3A inside. Thereby, the side light type surface light source device 1 forms a light emitting surface on the light emitting surface 3B of the light guide plate 3, and forms a surface light source by the illumination light emitted from the point light source.

[0009]

By the way, in such a sidelight type surface light source device 1, as shown in FIG.
There is a problem that the emitted light amount becomes non-uniform.

That is, in the rod member 4 of this kind,
The component below the critical angle is emitted to the incident surface 3A of the light guide plate 3 while propagating the illumination light incident from the end face toward the other end. Thereby, the illumination light L1 emitted from the rod-shaped member 4 is emitted from the emission surface of the rod-shaped member 4 due to the directivity of the rod-shaped member 4 inclined in the propagation direction, and is incident on the incident surface 3A of the light guide plate 3 while being inclined. Will do.

As a result, the illumination light L1 incident on the light guide plate 3
Does not travel straight toward the wedge-shaped tip side when viewed from the exit surface 3B side, but propagates at an angle to the incident surface as shown by the arrow X. Thereby, such a rod-shaped member 4
In the side light type surface light source device constituting the primary light source, the amount of emitted light is the lowest at the tip end side of the light guide plate 3 and at the corner on the point light source side of the rod-shaped member 4, and is opposite to this. The amount of emitted light gradually increases toward the corner.

When the amount of emitted light becomes non-uniform in this way, in the liquid crystal display device using the sidelight type surface light source device 1, luminance unevenness occurs on the display screen, and the quality of the display screen is significantly reduced. Become.

The present invention has been made in view of the above points, and uses a sidelight type surface light source device capable of making the amount of emitted light uniform as compared with the prior art, and using the sidelight type surface light source device. A liquid crystal display device is proposed.

[0014]

In order to solve the above-mentioned problems, according to the present invention, illumination light emitted from a predetermined primary light source is made incident on a side surface of a plate-like member, and the illumination light is bent to form the plate-like member. The present invention is applied to a sidelight type surface light source device that emits light from an emission surface. In this sidelight type surface light source device,
It has a rod-shaped member extending along the side surface, and illumination light emitted from a predetermined light source enters from an end face of the rod-shaped member, and is emitted from a surface along the side surface of the plate-shaped member. The primary light source is configured to supply the side surface of the primary light source. At this time, in the plate-shaped member, a pair of sloped protrusions are repeatedly formed on the side surface in the longitudinal direction of the side surface.

At this time, the projection is formed in a triangular cross section by directly connecting the pair of slopes.

At this time or instead, the light source is constituted by a light emitting diode.

Further, in the liquid crystal display device, the liquid crystal display panel is illuminated by any of these side light type surface light source devices.

The side light type surface light source device has a rod-like member extending along the side surface of the plate-like member, and illuminating light emitted from a predetermined light source is made incident from an end face of the rod-like member to form a plate-like member. If the primary light source is configured to emit light from the surface along the side surface and supply the light to the side surface of the plate member, the rod-shaped primary light source can be formed by the illumination light from the point light source.

At this time, the illumination light emitted from the rod-shaped light source is emitted with directivity toward the end face of the primary light source opposite to the light source side end face. When the side surface of the plate-shaped member is formed by a flat surface, illumination light having this directivity enters from the side surface, and this directivity is slightly reduced by the refractive index of the plate-shaped member. As a result, the light propagates through the inside of the plate member and is emitted from the emission surface. Accordingly, when the side surface of the plate-like member is formed of a flat surface, the amount of emitted light becomes non-uniform in accordance with the directivity.

On the other hand, if a pair of sloped projections are repeatedly formed on the side surface of the plate-shaped member in the longitudinal direction of the side surface, the illumination light is applied to the plate-shaped member from one slope facing the point light source. After being incident, the light is reflected by the other inclined surface, whereby the directivity can be corrected such that the illumination light travels substantially straight to the front end side of the plate-like member when viewed substantially from the emission surface side.
As a result, nonuniformity of the emitted light quantity due to the inclined directivity is avoided, and the emitted light quantity distribution is made uniform.

At this time, if the projections are formed to have a triangular cross section by directly connecting the pair of slopes, the amount of emitted light can be made uniform with a simple configuration.

At this time or in place of this, if the light source is constituted by a light emitting diode, a side light type surface light source device can be constituted with high reliability.
In addition, the overall shape can be reduced in size and weight.

Further, in the liquid crystal display device, when the liquid crystal display panel is illuminated by any of these side light type surface light source devices, it is possible to display a high quality display screen with reduced luminance unevenness on the display screen.

[0024]

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

(1) First Embodiment FIG. 1 is an exploded perspective view showing a sidelight type surface light source device according to a first embodiment of the present invention. In this embodiment, the liquid crystal display panel is configured by illuminating the liquid crystal display panel with the side light type surface light source device 10.

In the sidelight type surface light source device 10, after the reflection sheet 15 is bent and disposed on a frame (not shown), a prism formed of the light guide plate 11, the light diffusion sheet 13, and the light control member is provided inside the reflection sheet 15. The sheets 14 are sequentially stacked and arranged, the primary light source 12 is arranged on the side of the light guide plate 11, and then the primary sheet 12 side of the reflection sheet 15 is bent.

The primary light source 12 is provided on the incident surface 11 of the light guide plate 11.
A. A bar-shaped member 16 extending along A
And a point light source 17 which receives the illumination light L from one end surface 16A of the light source.

The rod member 16 is provided on the light exit surface 11 of the light guide plate 11.
It is formed by, for example, injection-molding acrylic so that the cross section is formed by a wedge-shaped shape with a cut end when the cross section is cut by a plane substantially parallel to B. The point light source 17 is formed of a light emitting diode, and the emission surface is adhered to the end surface 16A of the rod-shaped member 16 by, for example, a transparent adhesive, and is held by the rod-shaped member 16.

As a result, as shown in FIG. 2, the primary light source 12 has a surface 16B of the rod-shaped member 16 on the light guide plate 11 side (hereinafter referred to as an emission surface) and a surface facing the emission surface 16B (hereinafter referred to as a back surface). 16C is repeatedly reflected to propagate the illumination light L incident from the end face 16A of the rod-shaped member 16, and at the time of reflection at the emission face 16B and the back face 16C, components smaller than the critical angle are respectively emitted from the emission faces 16B and 16C. The light exits from the back surface 16C. As a result, the primary light source 12 is
Is emitted, and the illumination light emitted from the point light source 17 forms a rod-like light source.

The illumination light L emitted from the point light source 17 in this manner is repeatedly reflected between the emission surface 16B and the back surface 16C and propagates inside the rod-shaped member 16, while being transmitted through the rod member 16.
6C, the angle of incidence of the illumination light L with respect to the exit surface 16B is reduced.
B is emitted from B. Therefore, the illumination light L1 emitted from the emission surface 16B is formed such that the main emission direction is inclined toward the wedge-shaped tip.

The light guide plate 11 (FIG. 1) is formed by injection-molding, for example, acrylic made of a transparent member, and is formed in a wedge-shaped cross section with its tip cut off, and receives the illumination light L1 of the primary light source 12 from the incident surface 11A. I do. As a result, the light guide plate 11 emits components smaller than the critical angle from the emission surface 11B while propagating the illumination light L1 incident from the incident surface 11A inside. Thus, the side light type surface light source device 10 forms a light emitting surface on the light emitting surface 11B of the light guide plate 11, and forms a surface light source with the illumination light emitted from the point light source 17.

Further, the light guide plate 11 has a pair of slopes 18 as shown by partially enlarging the incident surface 11A by the symbol A.
Projections extending by A and 18B are formed repeatedly in the longitudinal direction of the incident surface 11A. Here, the projection is formed by directly connecting the pair of slopes 18A and 18B. Further, as shown in FIG. 2, the protrusions preferably have a repetition pitch W of 30 [μm] to 5 [μm].
[Mm] is set to a predetermined value, and the apex angle α is preferably set to a predetermined angle in a range of 35 to 80 degrees. Further, the projection is formed with a constant cross-sectional shape in the thickness direction of the light guide plate 11. Also, the slopes 18A and 18B correspond to the entrance surface 11A.
Are formed symmetrically with respect to the normal to the entrance surface 11A when macroscopically is regarded as a plane. In FIG. 2, the slopes 18A and 18B are emphasized.

Thus, the light guide plate 11 receives the illumination light L1 from one of the pair of slopes 18A and 18B facing the point light source 17 and then emits the illumination light L1 from the other slope 18B. As shown in FIG. 2, the directivity of the illumination light L1 is corrected such that the illumination light L1 is totally reflected and travels straight toward the wedge-shaped tip as seen from the emission surface 11B side.
That is, when the incident surface 11A is macroscopically regarded as a plane, the directivity of the illumination light L1 is corrected in a direction perpendicular to the incident surface 11A. In FIG. 2, the propagation direction of the illumination light in the case where the incident surface 11 </ b> A is formed by the flat surface M <b> 1 according to the conventional configuration is indicated by a symbol LX.

Further, as shown in FIG. 3 by cutting out FIG. 2 along the line BB, the light guide plate 11 reflects light between the emission surface 11B and a surface (hereinafter referred to as a back surface) 11C opposite to the emission surface 11B. The illumination light L1 thus incident from the side surface 11A is propagated in this manner, and a component equal to or smaller than the critical angle is emitted from the emission surface 11B and the back surface 11C during reflection at the emission surface 11B and the back surface 11C.

Further, the light guide plate 11 has a light scattering surface 11D on the back surface 11C. Here, this light scattering surface 11D
Is formed by selectively adhering a light-scattering ink using, for example, magnesium carbonate, titanium oxide, or the like as a pigment so that the degree of light scattering gradually increases from the incident surface 11A side toward the wedge-shaped tip. You. The light scattering surface 11D may be formed by partially forming the back surface 11C on a matte surface (textured surface) instead of the light scattering ink. Also in this case, similarly, the light scattering surface 11D forms, at a constant pitch, or at random, for example, a rectangular-shaped area having a matte surface, and the area of each rectangular-shaped area increases from the incident surface 11A side toward the wedge-shaped tip. It is formed to increase. Thereby, the light guide plate 11
Corrects the amount of outgoing light that decreases on the wedge-shaped tip side, and makes the amount of outgoing light uniform.

Although the illuminating light is scattered in this way, the light guide plate 11 basically reflects off the back surface 11C while propagating the illuminating light by repeatedly reflecting between the emission surface 11B and the back surface 11C. Each time, the angle of incidence of the illumination light with respect to the emission surface 11B is reduced, and a component smaller than the critical angle is emitted from the emission surface 11B. Therefore, the emission surface 11
The illumination light emitted from B is formed such that the main emission direction is inclined toward the wedge-shaped tip.

The light-diffusing sheet 13 prevents the light-scattering surface 11D of the back surface 11C from being recognized from the light-emitting surface 11B side, and furthermore, makes the shine, shadow, etc. of each part of the light guide plate 11 illuminated by the illumination light inconspicuous. Then, the illumination light emitted from the light guide plate 11 is scattered and emitted.

The prism sheet 14 is arranged to correct the directivity of the light guide plate 11. That is, the prism sheet 14 is formed of a translucent sheet material such as polycarbonate, and has a prism surface on the surface opposite to the side facing the light guide plate 11. The prism surface is formed by repeatedly forming projections having a triangular cross section extending substantially parallel to one direction. In this example, the projections are arranged so as to extend substantially parallel to the incident surface 11A. Thus, the prism sheet 14 corrects the main emission direction of the emitted light to the front direction of the emission surface 11B on the slope of the triangular projection.

The reflection sheet 15 (FIG. 1) is formed by a sheet-like irregular reflection member made of a white PET film or the like.
It is arranged so as to surround the light guide plate 11, the primary light source 12, and the like.
Thereby, the reflection sheet 15 reflects the illumination light leaking from each part other than the emission surface 11B and returns it to the light guide plate 11 or the primary light source 12, thereby improving the utilization efficiency of the illumination light. Here, as shown in FIG. 4, the reflection sheet 15 is formed by cutting one sheet material into a predetermined shape and then, for example, by applying a heat treatment in which a mold having a predetermined shape is pressed, a bending habit is formed at a location indicated by a broken line. Can be Further, the reflection sheet 15 is bent along the bending habit so as to surround the light guide plate 11, the primary light source 12, and the like, and is disposed on the frame.

That is, the reflection sheet 15 is formed on the back surface 11 C side of the light guide plate 11 so as to cover the light guide plate 11 and the primary light source 12, and the side surface on the primary light source 12 side rises, and is formed on the back surface 16 C of the rod-shaped member 16. The raised tip is bent so as to be in close contact with the light source so as to cover the surface of the primary light source excluding the emission surface 16B and the end surface 16A. On the side opposite to the primary light source 12, the light source rises so as to be in close contact with the side face on the wedge-shaped tip side of the light guide plate 11, and similarly rises on both side faces adjacent to the side face on the wedge-shaped tip side. The light guide plate 11 is formed so as to be in close contact with the side surface. Further, cutouts are formed on the side of the point light source 17 so that the driving lead wire can be drawn out from the point light source 17.

In the above configuration, the illumination light L emitted from the point light source 17 by the light emitting diode (FIGS. 1 and 2) enters from one end face 16A of the rod-like member 16 and passes between the emission face 16B and the back face 16C. The light is repeatedly reflected and propagates inside the rod-shaped member 16. Further, each time the light is reflected by the back surface 16C, the incident angle of the illumination light L with respect to the emission surface 16B is reduced, and components having a critical angle or less are emitted from the emission surface 16B,
As a result, the light is emitted with the main emission direction inclined toward the wedge-shaped tip. Further, at this time, the illumination light L propagating inside similarly leaks from the back surface 16C, and the leaked illumination light is reflected by the reflection sheet 15 and becomes the rod-shaped member 1.
Returned to 6. Thereby, the side light type surface light source device 1
0 means that the utilization efficiency of the illumination light is improved.

In this manner, the emission surface 16 of the rod-shaped member 16
The illumination light L1 emitted from B (FIG. 2) enters the incident surface 11A of the light guide plate 11 with directivity from the end surface 16A on the point light source 17 side to the other end surface side. At this time, the illumination light L1 is transmitted from the light guide plate 11 from the slope 18A facing the end face 16A side of the rod-shaped member 16 of the pair of slopes 18A and 18B constituting the protrusions repeatedly formed on the incident surface 11A.
And is totally reflected by the other slope 18B. As a result, the directivity is corrected so that the illumination light L1 travels straight in the wedge-shaped tip direction as viewed from the emission surface 11B, and unevenness in the amount of emitted light due to the inclination of the directivity is corrected.

The illumination light L1 thus incident on the light guide plate 11 (FIG. 3) is repeatedly reflected between the exit surface 11B and the rear surface 11C and propagates toward the wedge-shaped tip. A component equal to or smaller than the critical angle with respect to the surface 11B is emitted from the emission surface 11B. Similarly, illumination light is emitted from the back surface 11C, and the illumination light emitted from the back surface 11C is reflected by the reflection sheet 15 disposed on the back surface 11C side and returned to the light guide plate 11, thereby utilizing the illumination light. Efficiency is increased.

The illumination light emitted from the emission surface 11B is reflected on the light scattering surface 11 formed on the back surface 11C of the light guide plate 11.
After being scattered by the light diffusion sheet 13 so that D is not recognized, and furthermore, the brightness, shadow, and the like of each part of the light guide plate 11 illuminated by the illumination light become inconspicuous, the directivity is corrected by the prism sheet 14. You. Further, the illumination light illuminates the liquid crystal display panel, and a high-quality display screen without luminance unevenness is formed.

In illuminating the liquid crystal display panel in this manner, the illumination light leaking from a portion other than the emission surface of the light guide plate 11 is reflected by the reflection sheet 15 and reused.
The reflection sheet 15 is formed by cutting one sheet material into a predetermined shape, and then bending the sheet material to form a back surface 1 of the light guide plate 11.
1C, the side light, etc., whereby the sidelight type surface light source device 10 is created by a simple assembling operation.

According to the above configuration, a projection having a triangular cross section formed by a pair of inclined surfaces 18A and 18B is repeatedly formed on the incident surface 11A of the light guide plate 11 in the longitudinal direction of the incident surface 11A, so that the light exit surface 11B can be formed. The directivity of the illuminating light incident from the incident surface 11A can be corrected so as to proceed straight in the direction of the wedge-shaped tip when viewed, whereby the amount of emitted light can be made uniform as compared with the related art.

Further, at this time, a pair of slopes 18A and 18
By forming these projections by directly connecting B, these projections can be easily created and the amount of emitted light can be made uniform.

(2) Second Embodiment FIG. 5 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a second embodiment. In the sidelight type surface light source device, a primary light source 22 is applied instead of the primary light source 12 described above with reference to FIG.

That is, in the primary light source 22, the rod-shaped member 23 has a flat emission surface. Further, the back surface of the rod-shaped member 23 is formed by a curved surface so that the rate of reduction in plate thickness gradually decreases as the distance from the point light source 17 increases.

Thus, the primary light source 22 increases the light quantity of the illumination light emitted from the point light source 17 side, and adjusts the light quantity distribution of the illumination light L1 along the longitudinal direction of the rod 23.

According to the configuration shown in FIG. 5, even if the primary light source is constituted by the rod-shaped member 23 having the back surface formed by a curved surface,
The same effect as in the first embodiment can be obtained.

(3) Third Embodiment FIG. 6 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a third embodiment. In this sidelight type surface light source device, a primary light source 24 is applied instead of the primary light source 12 described above with reference to FIG.

In the primary light source 24, the rod-like member 25
Is formed in a shape obtained by cutting a conical shape by a plane passing through the central axis. That is, the rod-shaped member 25 has an emission surface formed in a triangular shape when viewed from the light guide plate 11 so that the width of the emission surface decreases as the distance from the point light source 17 increases. Further, the back surface of the rod-shaped member 25 is formed in an arc shape.

According to the configuration shown in FIG. 6, the same effect as in the first embodiment can be obtained even if the primary light source is constituted by the rod-shaped member 25 having a conical shape cut out by a plane passing through the central axis. Can be.

(4) Fourth Embodiment FIG. 7 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a third embodiment. In the sidelight type surface light source device, the primary light source is applied instead of the primary light source 12 described above with reference to FIG.

Here, this primary light source is formed by inverting the exit surface and the back surface of the rod 25 according to the third embodiment with respect to the entrance surface of the light guide plate 11.

As shown in FIG. 7, using a rod-shaped member 25 having a conical shape cut out by a plane passing through the central axis,
The same effect as in the first embodiment can be obtained even when the primary light source is configured by arranging the arc-shaped surface of the rod-shaped member 25 toward the light guide plate.

(5) Fifth Embodiment FIG. 8 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a fifth embodiment. In the sidelight type surface light source device, a primary light source 26 is applied instead of the primary light source 12 described above with reference to FIG.

In the primary light source 26, the rod-like member 27
Is created in a triangular pyramid shape. Further, the primary light source 26
The bar-shaped member 27 is arranged such that one flat surface of the bar-shaped member 27 faces the incident surface 11A of the light guide plate 11.

According to this embodiment, the same effect as that of the first embodiment can be obtained even if the primary light source is constituted by the triangular pyramid-shaped rod member 27.

(6) Sixth Embodiment FIG. 9 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a sixth embodiment. In the sidelight type surface light source device, the primary light source is applied instead of the primary light source 12 described above with reference to FIG.

Here, this primary light source is formed by inverting the exit surface and the back surface of the rod 27 according to the fifth embodiment with respect to the entrance surface of the light guide plate 11.

According to this embodiment, even if the primary light source is configured by using the bar-shaped member 27 having a triangular pyramid shape and arranging the inclined side of the bar-shaped member 27 toward the light guide plate, The same effect as in the embodiment can be obtained.

(7) Seventh Embodiment FIG. 10 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a seventh embodiment. In this sidelight type surface light source device, a primary light source 28 is applied instead of the primary light source 12 described above with reference to FIG.

In the primary light source 28, the rod-like member 29
Is formed in a quadrangular prism shape. Further, the rod-shaped member 29
A light scattering surface is formed on the back surface. Where the light scattering surface is
In order to scatter the illumination light, the back surface is entirely or partially roughened, or a light scattering ink such as white is adhered to the entire back surface or partially. As a result, the primary light source 28 causes the illumination light incident from the point light source 17 to propagate inside the rod-shaped member 29, and emits the illumination light by scattering on the light scattering surface.

When the illumination light is emitted in this manner,
In the rod-shaped member, a light scattering surface is formed such that the degree of light scattering changes as the distance from the point light source 17 increases. When the light scattering surface is formed by a rough surface, the degree of light scattering is set to change as the distance from the point light source 17 increases by changing the degree of the rough surface or the area of the rough surface per unit area. . Further, when the light scattering surface is formed by the attachment of the light scattering ink, by changing the amount of the attached ink (that is, the thickness of the attached ink) or the attached area of the ink per unit area,
The degree of light scattering is set to change as the distance from the point light source 17 increases. Thus, the primary light source 28 equalizes the amount of emitted illumination light in the longitudinal direction of the rod 29.

According to the structure shown in FIG. 10, even if the primary light source is formed by the quadrangular prism-shaped rod member 29,
The same effect as in the first embodiment can be obtained.

(8) Eighth Embodiment FIG. 11 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to an eighth embodiment. In the sidelight type surface light source device, a primary light source 30 is applied instead of the primary light source 12 described above with reference to FIG.

In the primary light source 30, the rod-shaped member 31
Is formed by connecting the rod-shaped member 23 described with reference to FIG. That is, the rod-shaped member 3
In 1, point light sources 17 are arranged on both end surfaces in the longitudinal direction. Thereby, the primary light source 30 increases the amount of illumination light incident on the light guide plate 11.

The rod-shaped members 31 are respectively provided with the point light sources 17.
It is formed so that the rate at which the plate thickness decreases gradually decreases as the distance increases. Thereby, the primary light source 30 increases the light amount on the light source 17 side.

According to the configuration shown in FIG. 11, point light sources 17 are arranged on both end surfaces in the longitudinal direction, and the rod-shaped members are formed such that the rate of reduction in the plate thickness gradually decreases as the distance from the point light sources 17 increases. Even if it does in this way, the effect similar to 1st Embodiment can be acquired.

(9) Ninth Embodiment FIG. 12 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a ninth embodiment. In the sidelight type surface light source device, a primary light source 32 is applied instead of the primary light source 12 described above with reference to FIG.

Here, the primary light source 32 is formed by arranging the point light source 17 on one end surface of the rod-shaped member 33. Rod member 33
Is a bar-shaped member 1 according to the first embodiment, except that projections of a predetermined shape are repeatedly formed on a back surface and / or an emission surface.
6 is created by the same configuration.

Here, as shown in a partially enlarged manner by the reference numeral C, the rod-shaped member 33 has a projection formed on the back surface and / or the light-emitting surface thereof, which has a triangular cross section and extends in the longitudinal direction of the rod-shaped member 33 repeatedly. Thereby, the rod-shaped member 33 becomes
In accordance with the inclination of the slope forming the protrusion, the incident angle distribution of the illumination light incident on the light guide plate 11 is corrected in the repetition direction of the protrusion.

According to the structure shown in FIG.
The same effects as in the first embodiment can be obtained by forming a primary light source by repeatedly forming protrusions extending in the longitudinal direction with a triangular cross section on the back surface of the light source.

(10) Tenth Embodiment FIG. 13 is an enlarged perspective view showing an incident surface side of a light guide plate applied to a sidelight type surface light source device according to a tenth embodiment. In this sidelight type surface light source device, this light guide plate 35 is applied instead of the light guide plate 11 described above with reference to FIG.

Here, in the light guide plate 35, similarly to the first embodiment, a pair of slopes 35 A and 35 B is repeatedly formed in the longitudinal direction of the incident surface 11 A of the light guide plate 11.
In this embodiment, the slopes 35A and 35B are the entrance surfaces 1A when the entrance surface 11A is macroscopically regarded as a flat surface.
The angles β1 and β2 with respect to the normal LH of 1A are formed by different angles. Further, the angles β1 and β2 are set such that the angle β1 of the slope 35A facing the point light source 17 is set to a small angle, whereas the angle β2 of the slope 35B forming a pair with the slope 35A is set to a large angle. It has been made like that.

As a result, when the light guide plate 35 is viewed from the wedge-shaped tip side toward the incident surface side, the one inclined surface 3 facing the point light source 17 side.
Compared with 5A, the other slope 35B is observed with a larger area.

That is, as shown in FIG. 14, the illumination light L1
Is incident on one inclined surface 35A (indicated by hatching in the drawing) facing the point light source 17 and then reflected by the other inclined surface 35B to travel straight through the light guide plate 11,
When the incident surface is viewed from the wedge-shaped tip side of the light guide plate 11, the other inclined surface 35B is brightly illuminated and observed by the illumination light L1, whereas the other inclined surface 35B facing the point light source 17 is observed.
A is observed dark.

As a result, the illumination light emitted from the emission surface of the light guide plate is close to the slopes 35A and 35A near the incidence surface.
The emitted light quantity pulsates in accordance with the brightness of 5B (see FIG. 15). However, in this embodiment,
This kind of pulsation can be reduced by observing the slope 35 </ b> B that is brightly illuminated and observed with a larger area (see FIG. 16). In FIGS. 15 and 16, in order to easily understand that the present embodiment has the above-described advantages, the difference in the amount of emitted light near the incident surface is emphasized. The area where the amount of emitted light is small is indicated by hatching.

According to the configuration shown in FIG. 13, the angles β1 and β2 of the slopes 35A and 35B with respect to the normal LH of the incident surface are set to different angles when the incident surface is macroscopically regarded as a plane. In addition to the same effects as in the first embodiment, the amount of emitted light in the vicinity of the incident surface can be made uniform, and luminance unevenness due to the formation of the pair of inclined surfaces can be reduced.

(11) Eleventh Embodiment FIG. 17 is an enlarged perspective view showing an incident surface side of a light guide plate applied to a sidelight type surface light source device according to an eleventh embodiment. In this sidelight type surface light source device, this light guide plate 37 is applied instead of the light guide plate 11 described above with reference to FIG.

Here, in the light guide plate 37, similarly to the first embodiment, a pair of slopes 37A and 37B is repeatedly formed in the longitudinal direction of the incident surface of the light guide plate 37. Further, the slopes 37A and 37B are formed by curved surfaces so that the entrance surface has a convex lens shape when cut by a surface parallel to the side surface 37F of the light guide plate 37 and viewed.

According to the configuration shown in FIG. 17, even if the projections are formed by forming the pair of slopes 37A and 37B by curved surfaces so that the entrance surface has a convex lens shape, the first projection can be formed.
The same effect as that of the embodiment can be obtained.

(12) Twelfth Embodiment FIG. 18 is an enlarged perspective view showing an incident surface side of a light guide plate applied to a sidelight type surface light source device according to a twelfth embodiment. In this sidelight type surface light source device, a light guide plate 39 is applied instead of the light guide plate 11 described above with reference to FIG.

Here, in the light guide plate 39, similarly to the first embodiment, protrusions extended by a pair of inclined surfaces 39A and 39B are repeatedly formed in the longitudinal direction of the incident surface of the light guide plate 39. Further, the slopes 39A and 39B are formed by curved surfaces so that the entrance surface has a concave lens shape when cut by a surface parallel to the side surface 39F of the light guide plate 39 and viewed.

According to the structure shown in FIG. 18, even if the projections are formed by forming the pair of inclined surfaces 39A and 39B by curved surfaces so that the entrance surface has a concave lens shape,
The same effect as that of the embodiment can be obtained.

(13) Thirteenth Embodiment FIG. 19 is a partially enlarged plan view showing an incident surface side of a light guide plate applied to a sidelight type surface light source device according to a thirteenth embodiment. It is. In this sidelight type surface light source device, the light guide plate 41 and the prism member 42 are applied instead of the light guide plate 11 described above with reference to FIG.

Here, the light guide plate 41 and the prism member 42
Is formed in a shape in which the light guide plate 11 described above with reference to FIG. 1 is cut into two members and separated from each other in a plane parallel to the incident surface in the vicinity of the incident surface.

According to the configuration shown in FIG. 19, the same effect as that of the first embodiment can be obtained even if a projection formed by a pair of inclined surfaces is formed on the incident surface of light guide plate 41 by another component. be able to. In addition, the light guide plate can be shared with a side light type surface light source device that constitutes a primary light source using, for example, a fluorescent lamp. If necessary, a light-scattering member may be interposed between the light guide plate 41 and the prism member 42.

(14) Fourteenth Embodiment FIG. 20 is a partially enlarged plan view showing a primary light source side of a sidelight type surface light source device according to a fourteenth embodiment. In this side light type surface light source device, FIG.
The primary light source 44 is replaced with the primary light source 12 described above.
Is applied.

Here, this primary light source 44 is formed by sequentially laminating the rod-like members 16 described above with reference to FIG. 1, and providing green, red and blue point light sources 17G, 17R, 17
B is formed. Here, the rod-shaped members 16 are stacked and arranged such that the emission surface and the back surface are in close contact. In addition, as for the rod-shaped member 16, each output surface and the back surface are bonded by an optical adhesive as needed. Also, point light sources 17G, 1
Each of 7R and 17B is constituted by a light emitting diode, and is disposed by being bonded to one end surface of the rod-shaped member 16 with an optical adhesive. Thus, the primary light source 44 emits substantially white illumination light to the light guide plate 11 obtained by adding the green, red, and blue illumination lights.

According to the configuration shown in FIG. 20, even when the green, red, and blue point light sources 17G, 17R, and 17B are arranged on the rod-shaped member 16 to emit substantially white illumination light to the light guide plate 11, By repeatedly forming a pair of inclined projections on the incident surface of the light plate 11, the same effect as that of the first embodiment can be obtained for illumination light of each color.
Thereby, a change in hue can be prevented.

(15) Fifteenth Embodiment FIG. 21 is a partially enlarged plan view showing a primary light source side of a sidelight type surface light source device according to a fifteenth embodiment. In this side light type surface light source device, FIG.
Instead of the primary light source 12 described above,
Is applied.

Here, the primary light source 46 is formed by sequentially laminating the rod members 16 described above with reference to FIG. 1 and arranging the point light sources 17 on each rod member. Here, the rod-shaped member 16
The point light sources 17 are stacked and arranged so as to face each other. In addition, the rod-shaped member 16 is laminated, as necessary, with its respective emission surface and back surface adhered by an optical adhesive. Point light source 1
Reference numeral 7 denotes a light-emitting diode, which is adhered to one end surface of the rod-shaped member 16 with an optical adhesive. As a result, the primary light source 46 adds the illumination lights of the two point light sources 17 and emits the light to the light guide plate 11, and separates the light guide plate 11.
The amount of the emitted illumination light is increased.

According to the configuration shown in FIG. 21, even when the two point light sources 17 are respectively arranged on the bar-shaped member 16 and the bar-shaped members are stacked so that the two point light sources 17 are opposed to each other, the light guide is performed. By repeatedly forming a pair of sloped projections on the light incident surface of the light plate 11, the same effect as in the first embodiment can be obtained.

(16) Sixteenth Embodiment FIG. 22 is a partially enlarged plan view showing a primary light source side of a sidelight type surface light source device according to a sixteenth embodiment. In this side light type surface light source device, FIG.
Is replaced with the primary light source 12 described above,
Is applied.

Here, the primary light sources 48 are each provided with a point light source 17 on a rod member 49 having a length in the longitudinal direction which is １ ／ of the rod member 16 described above with reference to FIG.
These rod-shaped members 49 are formed by sequentially arranging them along the incident surface of the light guide plate 11. Thereby, the primary light source 48 adds the illumination light of the three point light sources 17 and emits the light to the light guide plate 11,
The amount of illumination light emitted from the light guide plate 11 is increased accordingly.

According to the configuration shown in FIG. 22, the three point light sources 17 are respectively arranged on the rod members 49, and these rod members 49 are arranged along the incident surface of the light guide plate 11 to increase the amount of emitted light. However, by repeatedly forming a pair of inclined projections on the incident surface of the light guide plate 11, the first
The same effect as that of the embodiment can be obtained.

(17) Seventeenth Embodiment FIG. 23 is a plan view showing a sidelight type surface light source device according to a seventeenth embodiment. In the sidelight type surface light source device 50, the light exit surface of the light guide plate 52 is formed in a substantially rectangular shape, and each side surface surrounding the light exit surface is set as the incident surface of the illumination light.

In the light guide plate 52, projections having a triangular cross section formed by a pair of slopes are repeatedly formed on each of these incident surfaces.

In the side light type surface light source device 50, the primary light sources 12 are arranged on the respective incident surfaces, whereby the illumination light from the four point light sources is incident on the light guide plate 52, and the amount of light emitted from the light guide plate 52 is increased. I do.

According to the configuration shown in FIG. 23, even when each side surface of the light guide plate 52 is set as an incident surface to increase the amount of light emitted from the light guide plate 52, each incident surface of the light guide plate 52 has a pair of slopes. By repeatedly forming the protrusions, the same effect as in the first embodiment can be obtained.

(18) Eighteenth Embodiment FIG. 24 is a plan view showing a sidelight type surface light source device according to an eighteenth embodiment. In the side light type surface light source device 60, the primary light source 6 is formed by a rod-shaped member 61 formed to be bent along the side surface of the light guide plate 11.
Constituting No. 2.

That is, the rod-shaped member 61 includes a light guide portion 61A for guiding the illumination light incident from the point light source 17 disposed on the end surface along the side surface of the light guide plate 11, and an illumination light propagating through the light guide portion 61A. Surface 61B that bends the light guide plate 11 in the direction along the incident surface 11A of the light guide plate 11, and propagates the illumination light reflected by the reflection surface 61B to propagate the light guide plate 11
And a portion 61C for emitting light to the incident surface 11A. The rod-shaped member 61 includes a light guide portion 61A,
On the reflection surface 61B and the like, a reflection sheet is arranged so that the illuminating light that leaks is returned inside.

According to the structure shown in FIG. 24, the rod-shaped member 61 formed to be bent along the side surface of the light guide plate 11
Thus, even when the primary light source 62 is configured, the same effect as in the first embodiment can be obtained.

(19) Nineteenth Embodiment FIG. 25 is a plan view showing a sidelight type surface light source device according to a nineteenth embodiment. In the sidelight type surface light source device 70, the illumination light of the point light source 17 is incident on the rod-shaped member 16 by the light guide by the optical fiber 71.

That is, the optical fiber 71 is
6, one end face is arranged on the end face, and the point light source 17 is arranged on the other end face.

According to the configuration shown in FIG. 25, the same effect as in the first embodiment can be obtained even if the illumination light of the point light source 17 is made incident on the rod 16 by the light guide using the optical fiber 71. it can. In this embodiment, an external light condensing member that condenses external light is used instead of the point light source 17, and the member can be used as a light source.

(20) Other Embodiments In the above-described embodiment, a case has been described in which the primary light source is constituted by a rod-shaped member having a wedge shape, a triangular pyramid shape, or the like. However, the present invention is not limited to this. , For example, a quadrangular pyramid shape,
The present invention can be widely applied to a case where a primary light source is constituted by rod-shaped members having various shapes such as a cylindrical shape.

In the above-described embodiment, the case where the primary light source is constituted by the rod-shaped member made of the transparent member whose exit surface and back surface are not treated at all has been described. However, the present invention is not limited to this, and the seventh embodiment is not limited thereto. As in the embodiment, the present invention can be widely applied to a case where a light scattering surface is formed on the back surface.

Further, in the above-described embodiment, the case where the primary light source is constituted by the rod-shaped member made of the transparent member has been described. However, the present invention is not limited to this, and the constitution of the rod-shaped member can obtain the effects of the present invention. It can be arbitrarily selected within the range.

Further, in the above-described embodiment, a case has been described in which a pair of slopes are directly connected to repeatedly form a protrusion having a triangular cross section. However, the present invention is not limited to this, and for example, a pair of curved surfaces may be used. The slopes may be connected to repeatedly form projections having a corrugated cross section, or the slopes themselves may be formed by curved surfaces.

In the above-described embodiment, a case has been described in which a pair of inclined projections are repeatedly formed on the incident surface of the light guide plate without any surface treatment. However, the present invention is not limited to this. This slope may be formed as a rough surface, for example, and the slope may be used as a light diffusion surface. By doing so, it is possible to reduce luminance unevenness caused by repeatedly forming such projections.

Further, in the above-described embodiment, the case where a pair of sloped projections are repeatedly formed in a constant shape has been described. However, the present invention is not limited to this, and the directivity of illumination light emitted from the primary light source, etc. The slope of the slope may be gradually changed as the distance from the point light source of the primary light source increases, and the size of the protrusion as the distance from the point light source increases,
The pitch, shape, number of protrusions per unit length, and the like may be gradually changed. This makes it possible to adjust the distribution of the amount of emitted light in various ways.

In the above-described embodiment, the case where the light scattering surface is formed on the surface of the light guide plate has been described. However, the present invention is not limited to this. The present invention can be widely applied to the case where the light emitting device is formed on the front surface and the rear surface, and further to the case where both the light emitting surface and the front surface are not treated at all.

In the above embodiment, the case where the light guide plate is configured by setting the exit surface and the back surface to be flat surfaces has been described. However, the present invention is not limited to this, and the prism surface shape of the prism sheet may be changed. The present invention can be widely applied to a case where the light emitting surface is formed on the light emitting surface and / or the rear surface.

In the above-described embodiment, the case where the light guide plate is constituted by the transparent member has been described. However, the present invention is not limited to this, and the structure of the light guide plate may be arbitrary within a range where the effects of the present invention can be obtained. Can be selected.

In the above-described embodiment, the case where the light diffusion sheet and the prism sheet are arranged on the emission surface of the light guide plate has been described. However, the present invention is not limited to this, and the light diffusion sheet or the prism sheet is omitted. In this case, in addition to the prism sheet 14 described in the first embodiment, when a second prism sheet in which the prism surface of the prism sheet 14 and the repetition direction of the projections are orthogonal to each other is disposed, a predetermined polarization When a so-called polarization separation sheet that selectively transmits only outgoing light of a surface and selectively reflects outgoing light of a polarization plane perpendicular to the surface is provided, a wavelength conversion sheet that changes the wavelength of transmitted light is further provided. It can be widely applied to cases and the like.

Further, in the above-described embodiment, the case where the primary light source is disposed on one side surface of the light guide plate or the case where the primary light source is disposed on the four side surfaces of the light guide plate has been described. Without limitation, two sides or 3 of the light guide plate
It can be widely applied to the case where the primary light source is arranged on one side.

Further, in the above-described embodiment, the case where the light emitting diode as a point light source is arranged on the rod-shaped member has been described. However, the present invention is not limited to this. Thus, the present invention can be widely applied to the case where the rod-shaped member and the point light source are integrated.

Further, in the above-described embodiment, the case where one point light source is disposed on one rod-shaped member has been described. However, the present invention is not limited to this, and a plurality of light emitting diodes are disposed on one rod-shaped member. Accordingly, or by arranging one light emitting diode in which a plurality of light emitting diode chips are sealed on one rod-shaped member, the present invention can be widely applied to a case where a plurality of point light sources are arranged on one rod-shaped member.

In the above-described embodiment, the case where one reflection sheet is used by bending is described.
The present invention is not limited to this, and can be widely applied to the case where the reflection sheet is separated between the primary light source side and the light guide plate side.

Further, in the above-described embodiment, the case where the reflection sheet is constituted by the white irregular reflection member has been described. However, the present invention is not limited to this. For example, a regular reflection member such as a sheet material on which silver is deposited is used. It can be widely applied to the case.

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

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

[0127]

As described above, according to the present invention, a pair of inclined projections are repeatedly formed on the entrance surface of the plate-like member in the longitudinal direction of the entrance surface of the plate-like member, so that the amount of emitted light is uniform. Can be

[Brief description of the drawings]

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

FIG. 2 is a partially enlarged plan view showing an incident surface side of the sidelight type surface light source device of FIG. 1;

FIG. 3 is a cross-sectional view of FIG. 2 cut along line BB.

FIG. 4 is a development view showing the reflection sheet of FIG. 1;

FIG. 5 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a second embodiment.

FIG. 6 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a third embodiment.

FIG. 7 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a fourth embodiment.

FIG. 8 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a fifth embodiment.

FIG. 9 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a sixth embodiment.

FIG. 10 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a seventh embodiment.

FIG. 11 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to an eighth embodiment.

FIG. 12 is a perspective view showing a primary light source applied to a sidelight type surface light source device according to a ninth embodiment.

FIG. 13 is a perspective view showing a light guide plate applied to a sidelight type surface light source device according to a tenth embodiment.

FIG. 14 is a perspective view for explaining the operation of the light guide plate of FIG. 13;

FIG. 15 is a plan view showing the vicinity of an incident surface when a pair of inclined surfaces are set to have the same inclination.

16 is a plan view showing the vicinity of the incident surface of the light guide plate of FIG. 13 in comparison with FIG.

FIG. 17 is a perspective view showing a light guide plate applied to a sidelight type surface light source device according to an eleventh embodiment.

FIG. 18 is a perspective view showing a light guide plate applied to a sidelight type surface light source device according to a twelfth embodiment.

FIG. 19 is a plan view showing a light guide plate and a prism member applied to a sidelight type surface light source device according to a thirteenth embodiment.

FIG. 20 is a plan view showing a sidelight type surface light source device according to a fourteenth embodiment.

FIG. 21 is a plan view showing a sidelight type surface light source device according to a fifteenth embodiment.

FIG. 22 is a plan view showing a sidelight type surface light source device according to a sixteenth embodiment.

FIG. 23 is a plan view showing a sidelight type surface light source device according to a seventeenth embodiment.

FIG. 24 is a plan view showing a sidelight type surface light source device according to an eighteenth embodiment.

FIG. 25 is a plan view showing a sidelight type surface light source device according to a nineteenth embodiment.

FIG. 26 is a perspective view showing a conventional sidelight type surface light source device.

[Explanation of symbols]

1, 10, 50, 60, 70 ... side light type surface light source device, 2, 12, 22, 24, 26, 28, 30, 3,
2, 44, 46, 48, 61 ... primary light source, 3, 11,
35, 37, 39, 41, 52 ... light guide plate, 4, 16,
23, 25, 27, 29, 31, 33, 49, 61 ...
Rod-shaped member, 13: light reflecting sheet, 14: prism sheet, 15: reflecting sheet, 17, 17G, 17R, 1
7B Point light source, 18A, 18B, 35A, 35B, 3
7A, 37B, 39A, 39B ... slope, 42 ... prism member

Claims (4)

[Claims] 1. A sidelight type surface light source device for irradiating illumination light emitted from a predetermined primary light source from a side surface of a plate member, bending the illumination light and emitting the illumination light from an emission surface of the plate member. The primary light source has a rod-shaped member extending along the side surface. Illumination light emitted from a predetermined light source is incident from an end surface of the rod-shaped member, and is emitted from a surface along the side surface of the plate-shaped member. A side light type surface light source characterized in that a pair of sloped protrusions are repeatedly formed in the longitudinal direction of the side surface on the side surface of the plate member. apparatus. 2. The side light type surface light source device according to claim 1, wherein the projection is formed by directly connecting the pair of slopes to have a triangular cross section. 3. The side light type surface light source device according to claim 1, wherein the light source is a light emitting diode. 4. A liquid crystal display device, wherein the liquid crystal display panel is illuminated by the sidelight type surface light source device according to claim 1.