JPH11265610A - Light emitting diode, sidelight type surface light source device and liquid crystal displace device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the luminance unevenness near an incident surface by providing such a structure that, when the emitting end surface of the illuminating light emitted from a light emitting diode chip is seen by cutting it by a virtual plane including the optical axis of the illuminating light, at least part of the other part of the emitting and surface is protruded from the part of the emitting end surface crossed by the optical axis in the emitting direction of the illuminating light. SOLUTION: The illuminating light emitted from a light emitting diode 13 is incident on a light guide plate 12 through an incident surface 2A, and propagated in the light guide plate 12 while repeating the reflection between the reverse side and an emitting surface 2C. The illuminating light at this time is scattered by a light scattering surface formed on the reverse side every reflection by the reverse side, and the component of the critical angle or less to the increasing emitting surface 2C is consequently emitted from the emitting surface 2C. The thus-emitted illuminating light is incident on the light guide plate 2 so as to extend since the end surface of the light emitting diode 13 has a concave lens form. Accordingly, generation of a dark part near the incident surface 2A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light emitting diode,
Regarding the sidelight type surface light source device and the liquid crystal display device, when the cross section of the end surface that emits the illumination light cut out by a virtual plane including the optical axis of the illumination light,
A light-emitting diode chip is sealed with a light-transmitting resin so that another part of the light-emitting end surface projects in the light-emitting direction of the illumination light. With this configuration, it is possible to prevent uneven brightness near 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 is arranged on a side of a plate-like member (that is, a light guide plate), and illumination light emitted from the primary light source is transmitted from an end face of the light guide plate to the light guide plate. Incident. Further, the sidelight type surface light source device bends the illumination light and emits it from the plane of the light guide plate toward the liquid crystal display panel, whereby the overall shape can be reduced in thickness.

[0004] Such a side light type surface light source device is
There are a system in which the primary light source is configured by a rod-shaped light source such as a fluorescent lamp, and a system in which the primary light source is configured by a point light source such as a light emitting diode. The latter can simplify the driving circuit of the primary light source. And so on.

FIG. 25 is an exploded perspective view showing an example of the latter sidelight type surface light source device 1, and FIG. 26 is a cross-sectional view of FIG. 25 taken along line AA. The sidelight type surface light source device 1 is formed by arranging a primary light source 3 on a side of a light guide plate 2 and sequentially stacking a reflection sheet 4, a light guide plate 2, and a wavelength conversion sheet 6.

[0006] The primary light source 3 is formed by mounting a plurality of light emitting diodes 7 as point light sources on a holding member 8 such as a printed circuit board. (Referred to as an incident surface) 2A. Here, as this type of light emitting diode 7, for example, a blue light emitting diode that emits blue illumination light sealed in a rectangular resin package is used.

The light guide plate 2 is formed in a flat plate shape by injection molding, for example, acrylic (PMMA resin) made of a transparent member, and receives the illumination light of the primary light source 3 from an incident surface 2A. As a result, the light guide plate 2 repeatedly reflects between the reflection sheet 4 side plane (hereinafter referred to as back surface) 2B and the wavelength conversion sheet 6 side plane (hereinafter referred to as emission surface) 2C and propagates the illumination light. At the time of reflection at 2B and the exit surface 2C, components smaller than the critical angle are emitted from the back surface 2B and the exit surface 2C.

Further, the light guide plate 2 has a light scattering surface 2D formed on the back surface 2B. Here, this light scattering surface 2D corresponds to FIG.
As shown in FIG. 7, the back surface 2B is partially formed to have a textured surface so that the degree of light scattering increases gradually from the incident surface 2A side toward the other end. The light scattering surface 2D may be formed by selectively adhering a light scattering ink using, for example, magnesium carbonate, titanium oxide or the like as a pigment instead of the grained surface. More specifically, the light-scattering surface 2D forms, for example, a rectangular matted area with a constant pitch or a random arrangement, and the area of each rectangular-shaped area sequentially from the incident surface 2A side toward the other end. Is formed to increase. As a result, the light guide plate 2 has the back surface 2B and the emission surface 2C.
The illumination light that is repeatedly reflected and propagates between the light-emitting surface and the light-scattering surface 2D is scattered by the light scattering surface 2D, and the component that is smaller than the critical angle with respect to the emission surface 2C is increased. In the sidelight type surface light source device 1, the illumination light is thereby emitted from the emission surface 2C.

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

The wavelength conversion sheet 6 is a sheet material containing a fluorescent agent, and the fluorescent agent is excited by blue illumination light to emit light, thereby converting a part of the blue illumination light into yellow illumination light. , And add the blue and yellow illumination light to emit white illumination light. At this time, the wavelength conversion sheet 6
The white illumination light is diffused and emitted. Thereby, in the side light type surface light source device 1, the blue light emitting diode 7
Is used as the primary light source, and white illumination light is emitted from the emission surface 2C.

[0011]

However, such a sidelight type surface light source device 1 has a drawback that the amount of emitted light decreases as the distance from the light emitting diode 7 increases along the incident surface 2A. As a result, the sidelight type surface light source device 1 has a problem that a region B having a low luminance level is formed in the vicinity of the incident surface 2A, between the light emitting diodes 7, and the like, and luminance unevenness occurs near the incident surface. Incidentally, in the conventional sidelight type surface light source device 1, by using only the front end region excluding these regions B, the luminance unevenness is prevented and high-quality illumination light is emitted. .

If the amount of light emitted from these areas B can be increased to the same extent as the other areas, the light emitting surface of the light guide plate 2 can be used effectively, and the side light type surface light source device can be downsized accordingly. can do.

The present invention has been made in view of the above points, and it is an object of the present invention to propose a sidelight type surface light source device capable of preventing luminance unevenness near an incident surface.

[0014]

According to the first aspect of the present invention, there is provided a light emitting diode in which a light emitting diode chip is sealed with a light-transmitting resin. When the cross section of the emission end face of the illumination light is cut out by a virtual plane including the optical axis of the light, at least a part of the other part of the emission end face is in the emission direction of the illumination light from the part of the emission end face crossed by the optical axis. So that it protrudes.

In the invention of claim 2, claim 1
In the configuration of the above, when the emission end face is cut by a second virtual plane that includes the optical axis and is orthogonal to the previous virtual plane,
The portion of the emission end face crossing the optical axis is made to protrude most.

According to a third aspect of the present invention, the illumination light emitted from the light emitting diode according to the first or second aspect enters the end surface of the plate member and exits from the exit surface of the plate member.

Further, in the invention of claim 4, claim 3
The liquid crystal display panel is illuminated by the side light type surface light source device described in (1).

In the configuration of the first aspect, at least a part of the other part of the emission end face projects in the emission direction of the illumination light from the part of the emission end face traversed by the optical axis. The portion will be formed deeper than this portion. Therefore, the illumination light can be emitted so as to be wider than when the emission end face is formed by a plane perpendicular to the optical axis. Thus, when applied to a sidelight type surface light source device, the illumination light can be made to enter so as to largely spread in the direction along the incident surface of the plate-like member, whereby the illumination light can be distributed between the light emitting diodes.

According to the second aspect of the present invention, when the light emitting end face is cut out by the second virtual plane orthogonal to the virtual plane described in the first aspect and viewed from the light emitting end face, the portion of the light emitting end face crossing the optical axis is the most protruding. Thus, on the second virtual plane side, the light emitted from the end face is emitted with a small spread. Thus, when applied to a side light type surface light source device, illumination light can be incident with a small spread in the plate thickness direction of the plate member, and light leakage and the like can be prevented.

According to the configuration of claim 3, the present invention can be applied to a sidelight type surface light source device to emit high-quality illumination light, and in the configuration of claim 4, it can be applied to a liquid crystal display device to provide high-quality display. A screen can be formed.

[0021]

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

(1) First Embodiment FIG. 1 is a perspective view showing a main part of a side light type surface light source device applied to a liquid crystal display device according to a first embodiment of the present invention. In the sidelight type surface light source device 10, the reflection sheet 4 and the wavelength conversion sheet 6 described above with reference to FIG. 25 are arranged above and below the light guide plate 2, respectively. Supply. In FIG. 1, the same components as those of the sidelight type surface light source device 1 described above with reference to FIG. 25 are denoted by the corresponding reference numerals, and redundant description will be omitted.

This side light type surface light source device 10
The light reflecting member 12 is disposed between the next light source 11 and the incident surface 2A of the light guide plate 2. Here, the light reflecting member 12 is formed by, for example, injection molding white resin that efficiently reflects illumination light into a shape surrounding each light emitting diode 13 with a wall surface. The incident light 2 of the light guide plate 2 reflects the emitted illumination light by the wall surface.
Lead to A.

The light-emitting diode 13 is formed by sealing a light-emitting diode chip 13A (see FIG. 2) with a translucent resin such as epoxy or the like. Molded into a concave shape. Here, the shape of the end face is, when the emission end face is cut out by a virtual plane including the optical axis of the illumination light emitted from the light emitting diode chip 13A and the emission end face is crossed, a portion of the emission end face crossed.
It is formed in a concave lens shape so that both ends of the emission end face protrude in the emission direction of the illumination light. Light emitting diode 13
Are arranged such that this virtual plane is substantially parallel to the emission surface 2C of the light guide plate 2. Further, the end face shape is formed so as to be flat when cut out by a second virtual plane that is orthogonal to the virtual plane and includes the optical axis and the emission end face is viewed.

As a result, as shown in FIG. 2, the light emitting diode 13 spreads in the in-plane direction of the light exit surface 2C of the light guide plate 2 as compared with the conventional configuration in which the light exit end face is formed by a flat surface. And the illumination light LB. In FIG. 2, the illumination light in the case of the conventional configuration in which the emission end face is formed by a flat surface is indicated by reference numeral LA.

In the above configuration, the light emitting diode 13
(See FIGS. 1 and 26) are incident on the inside of the light guide plate 2 from the incident surface 2A, and the illumination light is
The light propagates inside the light guide plate 2 while repeating reflection between B and the emission surface 2C. At this time, the illumination light is
Every time the light is reflected by the light scattering surface 2
The component that is scattered by D and that is smaller than the critical angle with respect to the emission surface 2C that increases as a result is emitted from the emission surface 2C. At this time, part of the blue illumination light is converted into yellow illumination light by the wavelength conversion sheet 6 disposed on the emission surface 2C, and the yellow and blue illumination lights are added to white illumination light. Will be corrected.

As described above, the illumination light which is incident on the light guide plate 2 from the light emitting diode 13 and emitted therefrom (FIG. 2) has a concave lens shape when viewed from the emission surface 2C side of the light guide plate 2. Therefore, the light is incident on the light guide plate 2 so as to spread as compared with the case of the conventional configuration in which the emission end face is formed of a flat surface. As a result, the light can be sufficiently distributed between the light emitting diodes 13 near the incident surface 2A as compared with the related art, and the generation of a dark portion near the incident surface 2A is prevented.

According to the above configuration, when the emission end face is cut out by a virtual plane including the optical axis of the illumination light emitted from the light emitting diode chip 13A and viewed from the emission end face, both ends are located at a position closer to the emission end face crossed by the optical axis. The light emitting diode 13 is formed into a concave lens shape so that the light emitting diode 13 protrudes in the light emitting direction, so that the light can be sufficiently distributed between the light emitting diodes 13 near the incident surface 2A as compared with the related art. Accordingly, it is possible to prevent the occurrence of a dark portion near the incident surface 2A and reduce luminance unevenness near the incident surface.

(2) Second Embodiment FIG. 3 shows a main part of a sidelight type surface light source device applied to a liquid crystal display device according to a second embodiment of the present invention in comparison with FIG. FIG. The light emitting diode 14 is applied to this sidelight type surface light source device.

Here, the light emitting diode 14 is formed by sealing a light emitting diode chip with a translucent resin such as epoxy or the like, and is cut by a virtual plane including the optical axis of the illumination light emitted from the light emitting diode chip 13A. When viewed from the emission end face, both ends protrude in the emission direction of the illumination light from the part of the emission end face traversed by the optical axis, and are formed such that the emission end face part traversed by the optical axis and both ends are connected by a plane. You. The light emitting diode 14 is arranged such that this virtual plane is substantially parallel to the emission surface 2C of the light guide plate 2, and is cut off by a second virtual plane orthogonal to the virtual plane and including the optical axis. Are formed so that the end face shape becomes flat.

As shown in FIG. 3, the same effect as that of the first embodiment can be obtained even if the emission end face is formed.

(3) Third Embodiment FIG. 4 shows a partially enlarged light source of a sidelight type surface light source device applied to a liquid crystal display device according to a third embodiment of the present invention. It is a perspective view. The light emitting diode 15 is applied to the sidelight type surface light source device.

Here, the light-emitting diode 15 is formed in the same manner as the light-emitting diode 13 according to the first embodiment in the cross-sectional shape of the light-emitting end face viewed from the light-emitting surface 2C side of the light guide plate 2. Further, the light-emitting diode 15 is cut out by a second virtual plane including the optical axis and is orthogonal to the cross section viewed from the light-emitting surface 2C side. As described above, the cross-sectional shape of the emission end face viewed from the side is formed in a convex lens shape.

Thus, the light emitted from the light emitting diode 15 is not spread as compared with the case where the end face is formed flat when viewed from the side of the light guide plate 2. As a result, the light guide plate 2 causes the illuminating light that has spread from the side to leak out from a portion other than the emission surface 2C. The phenomena can be effectively avoided.

According to the structure shown in FIG. 4, the cross-sectional shape of the light-emitting end face of the light guide plate 2 as viewed from the light-emitting surface 2C is formed in the same manner as the light-emitting diode 13 according to the first embodiment.
When viewed from the second virtual plane including the optical axis and orthogonal to the cross section viewed from the emission surface 2C side, and viewed from the emission end face, the emission viewed from the side such that the portion crossed by the optical axis projects most. By forming the cross-sectional shape of the end face into a convex lens shape, light leakage can be prevented in addition to the effects of the first embodiment.

(4) Fourth Embodiment FIG. 5 shows a partially enlarged light source of a sidelight type surface light source device applied to a liquid crystal display device according to a fourth embodiment of the present invention. It is a perspective view. The light emitting diode 16 is applied to the sidelight type surface light source device.

Here, the light-emitting diode 16 is formed in the same manner as the light-emitting diode 13 according to the first embodiment in the cross-sectional shape of the light-emitting end face viewed from the light-emitting surface 2C side of the light guide plate 2. Further, the light emitting diode 16 is cut so as to be perpendicular to the cross section viewed from the light exit surface 2C side and cut out by a second virtual plane including the optical axis so that when viewed from the light emitting end surface, the portion crossed by the optical axis projects most. The cross-sectional shape of the emission end face viewed from the side is formed in a triangular shape. Thus, the light-emitting diode 16 prevents the emitted light from being spread due to the triangular slope when viewed from the side, similarly to the third embodiment.

According to the configuration shown in FIG. 5, the same effect as in the third embodiment can be obtained even if the cross-sectional shape of the light-emitting end face viewed from the side is triangular.

(5) Fifth Embodiment FIG. 6 shows a partially enlarged light source of a sidelight type surface light source device applied to a liquid crystal display device according to a fifth embodiment of the present invention. It is a perspective view. The light emitting diode 17 is applied to the sidelight type surface light source device.

Here, the light-emitting diode 17 has the same cross-sectional shape of the light-emitting end face as viewed from the light-emitting surface 2C side of the light guide plate 2, similarly to the light-emitting diode 14 according to the second embodiment.
Also, the cross-sectional shape of the emission end face viewed from the side is formed in a convex lens shape.

According to the structure shown in FIG. 6, the cross-sectional shape of the light-emitting end face of the light guide plate 2 as viewed from the light-emitting surface 2C is formed in the same manner as the light-emitting diode 14 according to the second embodiment.
By forming the cross-sectional shape of the emission end face viewed from the side into a convex lens shape, the same effect as the effect of the third embodiment can be obtained.

(6) Sixth Embodiment FIG. 7 shows a partially enlarged light source of a sidelight type surface light source device applied to a liquid crystal display device according to a sixth embodiment of the present invention. It is a perspective view. The light emitting diode 18 is applied to the sidelight type surface light source device.

Here, the light-emitting diode 18 has the same cross-sectional shape of the light-emitting end face as viewed from the light-emitting surface 2C side of the light guide plate 2 in the same manner as the light-emitting diode 14 according to the second embodiment.
Also, the cross-sectional shape of the emission end face viewed from the side is formed in a triangular shape.

According to the configuration shown in FIG. 7, the cross-sectional shape of the light-emitting end face of the light guide plate 2 as viewed from the light-emitting surface 2C is formed in the same manner as the light-emitting diode 14 according to the second embodiment.
By forming the cross-sectional shape of the emission end face as viewed from the side into a triangular shape, the same effect as the effect of the third embodiment can be obtained.

(7) Seventh Embodiment FIG. 8 shows a partially enlarged light source of a sidelight type surface light source device applied to a liquid crystal display device according to a seventh embodiment of the present invention. It is a perspective view. The light emitting diode 19 is applied to the sidelight type surface light source device.

Here, the light-emitting diode 19 is formed in a shape obtained by cutting a rectangular shape by a plane obliquely crossing the optical axis, whereby the light-emitting diode 19 is cut by a virtual plane including the optical axis of the illumination light, and the cross-sectional shape of the emission end face is observed. At this time, on one side of the optical axis, the portion crossing the optical axis is formed so as to protrude the most, but on the other side of the optical axis, the optical axis is the same as in the first embodiment. Is formed such that the portion crossing is closest to the light emitting diode chip side. The light-emitting diode 19 has a tip shape such that the cross-sectional shape is rectangular when viewed from the side.

Thus, as shown in FIG. 9, the light emitting diode 19 bends the emitted light in one direction and emits it when viewed from the emission surface 2C side of the light guide plate 2.

In the side light type surface light source device according to this embodiment, the light emitting diodes 19 are arranged in pairs by utilizing the characteristics of the light emitting diodes 19 (FIG. 8). Thus, the illumination light can be sufficiently distributed between the pair of light emitting diodes near the incident surface 2A.

According to the structure shown in FIG. 8, even if the light-emitting diode is formed in a shape obtained by cutting a rectangular shape by a plane obliquely crossing the optical axis, the same effect as in the first embodiment can be obtained. .

(8) Eighth Embodiment FIG. 10 shows a partially enlarged light source of a sidelight type surface light source device applied to a liquid crystal display device according to an eighth embodiment of the present invention. It is a perspective view. The light emitting diode 20 is applied to the sidelight type surface light source device.

Here, the light-emitting diode 20 has the same cross-sectional shape of the light-emitting end face as viewed from the light-emitting surface 2C side of the light guide plate 2 as the light-emitting diode 19 according to the seventh embodiment, and emits light when viewed from the side. The cross-sectional shape of the end face is formed in the shape of a convex lens, and is arranged in pairs as in the seventh embodiment.

According to the configuration shown in FIG. 10, light leakage can be prevented in addition to the effects of the seventh embodiment.

(9) Ninth Embodiment FIG. 11 is a partially enlarged view showing a light source of a sidelight type surface light source device applied to a liquid crystal display device according to a ninth embodiment of the present invention. It is a perspective view. The light emitting diode 21 is applied to the sidelight type surface light source device.

Here, the light-emitting diode 21 has the same cross-sectional shape of the light-emitting end face as viewed from the light-emitting surface 2C side of the light guide plate 2 as the light-emitting diode 19 according to the seventh embodiment, and the light-emitting diode 21 as viewed from the side. The cross-sectional shapes of the end faces are formed in a triangular shape, and are arranged in pairs as in the seventh embodiment.

According to the configuration shown in FIG. 11, in addition to the effect of the seventh embodiment, light leakage can be prevented.

(10) Tenth Embodiment FIG. 12 is a partially enlarged view of a light guide plate of a sidelight type surface light source device applied to a liquid crystal display device according to a tenth embodiment of the present invention. FIG. The light emitting diode 19 described in the seventh embodiment is applied to the sidelight type surface light source device.

Here, the light emitting diode 19 is arranged so as to be inclined such that the flat emission end face is in close contact with the incidence face 2 A of the light guide plate 2. Further, a pair is formed by the two light emitting diodes 19, and illumination light is supplied by the other light emitting diode 19 to a region where the illumination light of one light emitting diode 19 is not distributed.

According to the structure shown in FIG. 12, the light emitting diode 19 is inclined and the light emitting diode 19 is arranged by bringing the inclined light emitting end face of the light emitting diode 19 into close contact with the light incident surface of the light guide plate 2.
The same effect as in the first embodiment can be obtained.

(11) Other Embodiments In the above-described embodiment, the case where the illumination light is made incident on the light guide plate whose entrance surface is formed by a flat surface has been described, but the present invention is not limited to this. Instead, the present invention can be widely applied to a case where illumination light is incident on a light guide plate having various shapes of incident surfaces.

That is, FIG. 13 shows the light guide plate having a concave lens shape on the incident surface of the light guide plate when viewed from the exit surface side. The concave lens shape of the light guide plate further widens the illumination light and makes it enter the light guide plate. can do.

FIG. 14 is a view in which the triangular shape is repeatedly formed on the light incident surface of the light guide plate when viewed from the light exit surface side of the light guide plate. In this case, the illumination light is further expanded by these triangular shapes to further increase the light guide plate. Can be incident.

Further, FIG. 15 shows that the waveform is repeatedly formed on the incident surface of the light guide plate when viewed from the light exit surface side of the light guide plate. Even in this case, the illumination light is further expanded and incident on the light guide plate. be able to.

FIG. 16 shows the waveform shape of FIG. 15 with added strength, and FIG. 17 shows the waveform shape of this type formed only on the portion facing the light emitting surface of the light emitting diode 13. Even in this case, the illumination light can be further expanded and incident on the light guide plate.

FIG. 18 shows a waveform obtained by repeatedly forming a waveform on the light incident surface of the light guide plate and forming a concave lens as a whole as shown by a broken line in FIG.
Is obtained by adding strength to the waveform shape of FIG.
Even in this case, the illumination light can be further expanded and incident on the light guide plate.

FIGS. 20 and 21 show the triangular shape and the waveform shape formed in this manner, and the inclination of the surface H facing outward from the optical axis is selected.
Depending on the inclined surface H, the illumination light LA is prevented from being positively distributed in the optical axis direction, and no shadow is formed on the surface M forming a pair with the inclined surface H. In this way, the illumination light can be efficiently distributed according to the triangular shape and the waveform shape.

FIGS. 22 and 23 each show a step formed in a portion facing the light emitting surface of the light emitting diode 13, and the light emitting diode 13 is positioned by the step. Even in this case, the same effect as in the first embodiment can be obtained.

FIG. 24 shows the configuration described above with reference to FIG. 12 in which the light guide plate has an asymmetric concave lens shape with respect to the incident surface, and a further step is provided in the light guide plate as compared with the configuration described above with reference to FIG. Can be distributed to each part.

In the examples of the light emitting diode shown in FIGS. 4, 6, and 10, a ridge line is drawn between the light emitting end surface and the light emitting surface side for drawing. From the viewpoint of favorably controlling the emission direction of the emitted light, it is preferable that the emission end face and the face on the emission face side be connected smoothly so that such a ridgeline does not appear.

In the above embodiment, the case where the light scattering surface is formed by forming the textured surface on the back surface of the light guide plate has been described. However, the present invention is not limited to this, and the light scattering sheet or the like may be disposed. It can be widely applied to the case where a light scattering surface is formed.

In the above-described embodiment, a case has been described in which a blue light emitting diode is used as a point light source and the blue illumination light is corrected to white light by a wavelength conversion sheet disposed on an emission surface. The present invention is not limited to this, using point light sources of various colors, when illuminating light of this point light source is directly emitted from the light guide plate, or by converting it into illumination light of a desired color by a wavelength conversion sheet. It can be widely applied when emitting light.

In the above-described embodiment, the case where the light guide plate is made of a transparent member has been described. However, the present invention is not limited to this, and various types of members may be used as long as the effects of the present invention can be obtained. It can be widely applied when making a light plate.

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

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

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.

[0075]

As described above, according to the present invention, when the cross section of the exit end surface that emits illumination light is cut by a virtual plane including the optical axis of the illumination light, the portion of the exit end surface that crosses the optical axis is A light-emitting diode chip is sealed with a translucent resin so that at least a part of the other part of the emission end face projects in the emission direction of the illumination light. By configuring the liquid crystal display device, it is possible to prevent luminance unevenness near the incident surface.

[Brief description of the drawings]

FIG. 1 is a perspective view partially showing a sidelight type surface light source device applied to a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a plan view for explaining a light emitting diode in the side light type surface light source device of FIG. 1;

FIG. 3 is a plan view for explaining a light emitting diode applied to a side light type surface light source device according to a second embodiment in comparison with FIG. 2;

FIG. 4 is a perspective view for explaining a light emitting diode applied to a side light type surface light source device according to a third embodiment.

FIG. 5 is a perspective view for explaining a light emitting diode applied to a sidelight type surface light source device according to a fourth embodiment in comparison with FIG. 4;

FIG. 6 is a perspective view for explaining a light emitting diode applied to a side light type surface light source device according to a fifth embodiment in comparison with FIG. 4;

FIG. 7 is a perspective view for explaining a light emitting diode applied to a sidelight type surface light source device according to a sixth embodiment in comparison with FIG.

FIG. 8 is a perspective view for explaining a light emitting diode applied to a side light type surface light source device according to a seventh embodiment in comparison with FIG. 4;

FIG. 9 is a plan view showing a behavior of light emitted from the light emitting diode of FIG. 8;

FIG. 10 is a perspective view for explaining a light emitting diode applied to a side light type surface light source device according to an eighth embodiment in comparison with FIG.

FIG. 11 is a perspective view for explaining a light emitting diode applied to a side light type surface light source device according to a ninth embodiment in comparison with FIG. 4;

FIG. 12 is a plan view showing an incident surface side of a sidelight type surface light source device according to a tenth embodiment.

FIG. 13 is a plan view showing an incident surface side of a sidelight type surface light source device according to another embodiment.

FIG. 14 is a plan view showing a case where a triangular shape is repeatedly formed on an incident surface of a light guide plate.

FIG. 15 is a plan view showing a case where a waveform shape is repeatedly formed on an incident surface of a light guide plate.

FIG. 16 is a plan view showing a case where the waveform shape of FIG.

FIG. 17 is a plan view showing a case where the waveform shape of FIG. 16 is formed only in a portion facing an emission surface of a light emitting diode.

FIG. 18 is a plan view showing a case where the incident surface of the light guide plate is formed in a concave lens shape as a whole in addition to the waveform shape of FIG.

FIG. 19 is a plan view showing a case where the waveform shape of FIG. 18 is given strength.

20 is a plan view showing a case where the angle of the triangular slope in FIG. 14 is selected.

21 is a plan view showing a case where the angle of the slope of the waveform shape of FIG. 15 is selected.

FIG. 22 is a plan view showing a case where a step portion is formed on an incident surface of a light guide plate.

FIG. 23 is a plan view showing a case where a step portion is formed on the incident surface of the light guide plate and a waveform is formed.

FIG. 24 is a plan view showing a case where a concave portion is formed on the incident surface of the light guide plate in the configuration of FIG.

FIG. 25 is an exploded perspective view showing a conventional side light type surface light source device.

FIG. 26 is a cross-sectional view of FIG. 25 taken along line AA.

FIG. 27 is a plan view showing the back surface of the light guide plate 2.

[Explanation of symbols]

1, 10 side light type surface light source device, 2 light guide plate, 2A incident surface, 3 primary light source, 4 reflection sheet, 6 wavelength conversion sheet, 7, 13 to 21 Light emitting diode

Claims (4)

[Claims] 1. A light emitting diode in which a light emitting diode chip is sealed with a translucent resin, wherein a cross section of an emission end face of the illumination light is cut by a virtual plane including an optical axis of illumination light emitted from the light emitting diode chip. A light emitting diode, wherein at least a part of another part of the emission end face protrudes in an emission direction of the illumination light from a part of the emission end face crossed by the optical axis. 2. When the output end face is cut off by a second virtual plane that includes the optical axis and is orthogonal to the virtual plane and the output end face is viewed, a portion of the output end face crossed by the optical axis is most protruded. The light emitting diode according to claim 1, wherein 3. A sidelight type wherein illumination light emitted from the light emitting diode according to claim 1 or 2 is incident on an end face of the plate-like member and is emitted from an emission surface of the plate-like member. Surface light source device. 4. A liquid crystal display device, wherein a liquid crystal display panel is illuminated by the sidelight type surface light source device according to claim 3.