JPH09304627A - Sidelight type surface light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively avoid the leakage of light caused by gaps between a holding member and various kinds of members by forming a light reflection sheet reflecting illuminating light of sheet material having elasticity with respect to bend, folding back and arranging the light reflection sheet and pressing a plate-like member through a part folded back and overlapping. SOLUTION: A light guiding plate 2 is held to be pressed to a frame 21 by a lamp cover 24 with a light diffusion sheet 22 and prism sheets 6 and 7 through a reflector 25 and the reflection sheet 27. At such a time, the plate 2 is interposed so as not form the gaps among the reflection sheet 27, the plate 2 and the diffusion sheet 22 and the prism sheets 6 and 7, between the frame 21 and the prism sheet 7 and between the lamp cover 24 and the reflection sheet 27 by the elastic force of the doubly overlapped part of the reflector 25 in a thickness direction, repulsive force of the bent part thereof and the elastic force of the reflection sheet 27 in the thickness direction.

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 applied to a liquid crystal display device or the like, and for example, a side-light type surface light source device in which the plate thickness of a plate-shaped member becomes thinner as the distance from the incident surface increases. It is applied to a surface light source device. According to the present invention, in this sidelight type surface light source device, a reflector or a reflection sheet is formed of a sheet material having elasticity against bending, and the reflector or the like is folded back so that the overlapping portion further overlaps with the plate-shaped member. By pressing the plate member by the holding member via the overlapping portion, light leakage due to the gap between the holding member and various members is effectively avoided.

[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 side light type surface light source device, a primary light source composed of a rod-shaped light source is arranged laterally of a plate-shaped member (that is composed of a light guide plate), and illumination light emitted from this primary light source is provided on an end face of the light guide plate. Incident on the light guide plate. Further, the side light type surface light source device bends this illumination light and emits it toward the liquid crystal panel from the plane of the light guide plate, whereby the overall shape can be made thin.

[0004] Such a side light type surface light source device is
A method in which the light guide plate is formed with a substantially uniform thickness,
There is a type in which the thickness of the light guide plate is gradually reduced as the distance from the primary light source increases, and the latter can emit illumination light more efficiently than the former.

That is, FIG. 8 is an exploded perspective view showing an example of the latter side light type surface light source device, and FIG.
It is sectional drawing which cuts and shows FIG. 8 by the AA line. In this sidelight type surface light source device 1, a primary light source 3 is arranged on a side of a light guide plate 2, and a reflection sheet 4, a light guide plate 2, a light diffusion sheet 5, and prism sheets 6 and 7 which are light control members are sequentially laminated. Formed. Of these, the primary light source 3 is formed by surrounding a fluorescent lamp 8 made of a cold cathode tube with a reflector 9, and the end surface 2 of the light guide plate 2 from the opening side of the reflector 9.
Illumination light is incident on A. Here, the reflector 9 is formed of, for example, a sheet material that specularly or irregularly reflects incident light.

The light guide plate 2 is formed, for example, by injection molding acrylic (PMMA resin) into a wedge-shaped cross section, and receives the illumination light of the primary light source 3 from an incident surface 2A which is an end surface. As a result, the light guide plate 2 has a reflection sheet 4 side plane (hereinafter referred to as a slope) 2B and a light diffusion sheet 5 side plane (hereinafter referred to as an exit plane).
2C is repeatedly reflected to propagate the illumination light, and at the time of reflection at the inclined surface 2B and the exit surface 2C, components smaller than the critical angle are emitted from the inclined surface 2B and the exit surface 2C.

Further, in the light guide plate 2, a light diffusion surface is formed on the inclined surface 2B so that the degree of light diffusion increases from the incident surface 2A side toward the wedge-shaped tip. Here, the light diffusing surface is formed by selectively adhering a light diffusing ink or forming the slope 2B partially on a satin surface (texture surface). That is, the light-diffusing ink is printed at a constant pitch or randomly, for example, in a rectangular shape, and at this time, the area of each rectangular shape increases from the incident surface 2A side toward the wedge-shaped tip. Further, in the case of using a satin-finished surface, the area of the satin-finished surface is formed in the same manner at a constant pitch or randomly, for example, in a rectangular shape so that the area of each rectangular shape increases from the incident surface 2A side toward the wedge-shaped tip. Set. As a result, the light guide plate 2 corrects the emitted light amount that is reduced on the wedge-shaped tip side and makes the light amount distribution of the emitted light uniform.

Although the illumination light is diffused in this manner, the light guide plate 2 basically includes the inclined surface 2B and the emission surface 2C.
While the illumination light is propagated by being repeatedly reflected between and, the incident angle of the illumination light with respect to the emission surface is reduced each time the light is reflected by the inclined surface, and of these components below the critical angle are emitted from the emission surface 2C. . Therefore, the illumination light emitted from the emission surface 2C is formed such that the main emission direction is inclined toward the front end of the wedge shape.

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 inclined surface 2B to form the light guide plate 2. , Thereby improving the utilization efficiency of the illumination light.

The prism sheets 6 and 7 are arranged to correct the directivity of the light guide plate 2, and the light diffusing sheet 5 is further illuminated so that the light diffusing surface of the inclined surface 2B is not recognized from the exit surface 2C side. The light guide plate 2 is arranged so as to make the brightness, shadow, etc. of each part of the light guide plate 2 illuminated by light inconspicuous.

That is, the light diffusion sheet 5 diffuses and emits the illumination light emitted from the light guide plate 2. The prism sheets 6 and 7 are formed of a translucent sheet material such as polycarbonate, and a prism surface is formed on the surface opposite to the side facing the light guide plate 2. This prism surface is formed by repeating projections having a triangular cross section that extend substantially parallel to one direction. In the case of this example, in the prism sheet 6 on the light guide plate 2 side, the projections are parallel to the incident surface 2A. To extend to
The prism sheet 7 is arranged so that the protrusion extends in a direction orthogonal to the incident surface 2A.

As a result, the prism sheets 6 and 7 are the slopes of the triangular protrusions, and correct the main emission direction of the emitted light to the front direction of the emission surface 2C. As the prism sheet, a so-called double-sided prism sheet in which prism surfaces are formed on both sides and the prism sheets 6 and 7 are integrated may be used. Thus, in the sidelight type surface light source device 1, the emitted light can be efficiently emitted in the front direction as compared with the sidelight type surface light source device in which the light guide plate is formed with a substantially uniform plate thickness. I have.

[0013]

The sidelight type surface light source device of this type is entirely held by a frame-shaped frame and is used in this state in combination with a liquid crystal display panel. As shown in FIG. 10, this frame 10
On the side of the primary light source 3, the light guide plate 2 is formed so as to be sandwiched between the emission surface 2C and the inclined surface 2B, whereby the illumination light leaks from the gap between the frame 10 and the prism sheet 7, and the liquid crystal display panel is directly connected. It is designed not to illuminate.

However, when a portion AR where the frame 10 overlaps the emission surface 2C is formed to be narrow (hereinafter, such a frame is referred to as a frame having a narrow frame) and the side light type surface light source device of this type is downsized, the Part AR is a light guide plate 2
It becomes difficult to sufficiently press the members such as, and a minute gap is generated.

As a result, in the conventional side light type surface light source device, when the frame is narrowed, this portion A
There is a problem that so-called light leakage occurs in which the illumination light L1 leaks from R. The illuminating light L1 thus leaked forms uneven brightness on the display screen of the liquid crystal display panel on the side of the emission surface 2C. Also slope 2B
On the side, the utilization efficiency of the illumination light is reduced accordingly.

The present invention has been made in consideration of the above points, and proposes a side light type surface light source device capable of effectively avoiding light leakage even when the frame has a narrow frame. It is what

[0017]

In order to solve such a problem, in the present invention, a light reflection sheet arranged so as to surround a light source so as to form an opening toward an end face of a plate-like member is bent and bent. It is formed of an elastic sheet material. Further, in the holding member for holding the light reflecting sheet near the front end face, the light reflecting sheet is bent and pressed so that the leading end portion partially overlaps and the overlapped portion overlaps the front plate member. Thus, the plate-shaped member is pressed through the overlapping portion.

Alternatively, the light reflecting sheet that reflects the illumination light leaking from the plate-like member and returns it to the plate-like member is made of a sheet material having elasticity against bending so that the tip thereof projects toward the light source side. To form. Further, in the holding member that holds the light source on the end face, the protruding portion of the light reflecting sheet is bent so that the protruding portion of the light reflecting sheet partially overlaps and the overlapping portion overlaps the plate member. By pressing the reflection sheet, the plate-shaped member is pressed through the overlapping portion.

Further, in these configurations, the overlapping portions of the light reflecting sheet are arranged so as to straddle the edge of the end face.

In these configurations, the light reflection sheet is
It is formed of a sheet material of which the thickness is partially changed by the pressing force.

More specifically, it is formed of a foamed sheet material.

Further, in these configurations, the holding member is
At least a part is formed of a metal plate material having elasticity.

If the light reflecting sheets having elasticity are bent and overlapped and the overlapped portion is arranged so as to overlap the plate-like member, a large pressing force can be obtained in the overlapped portion due to the force against the bending. be able to. Therefore, if the holding member presses the plate-shaped member through the overlapping portion, it is possible to effectively avoid the generation of the gap due to the pressing force of the light reflecting sheet.

Thus, the object to be bent is applied to the light reflecting sheet of the light source or the light reflecting sheet of the plate member,
It is possible to effectively avoid light leakage by effectively utilizing the members used in the side light type surface light source device of this type.

Further, in these structures, if the overlapping portion of the light reflecting sheet is arranged so as to straddle the edge of the end face, light leakage will occur even when the frame corresponding to the holding member is narrowed. Can be effectively avoided.

Further, in these structures, if the light reflecting sheet is formed of a sheet material of which the thickness is partially changed by the pressing force, more specifically, a foamed sheet material,
Even when the gaps are unevenly formed, it is possible to effectively avoid light leakage by filling the gaps by deforming the light reflection sheet.

Further, in these configurations, if at least a part of the holding member is formed of an elastic metal plate material, the pressing force from the case when mounted on a liquid crystal display device or the like can be relaxed, It is possible to effectively avoid the generation of the gap due to the pressing force or the like.

[0028]

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

(1) First Embodiment FIG. 2 is an exploded perspective view showing a side light type surface light source device according to a first embodiment of the present invention when viewed from the side of a slope. The sidelight type surface light source device 20 is formed so as to be entirely held by a frame 21 having a narrow frame. In the first embodiment, the same configurations as those in FIGS. 8 and 9 are designated by the corresponding reference numerals, and the duplicated description will be omitted.

That is, the side light type surface light source device 20.
After the primary light source 3 is arranged on the frame 21 in advance, the prism sheets 6 and 7, the light diffusion sheet 22, the light guide plate 2,
The reflection sheets 27 are sequentially stacked and housed in the frame 21, and subsequently, the light guide plate cover 23 and the lamp cover 24 are arranged and assembled. Further, the sidelight type surface light source device 20 is subsequently provided with a liquid crystal display panel on the exit surface side, and is assembled into the liquid crystal display device.

Here, the frame 21 is formed into a rectangular frame shape by injection-molding black resin, for example, and each side forming the frame shape is formed into an L-shaped cross section. On the other hand, the light guide plate cover 23 is formed by punching and bending a stainless steel plate material having a spring property, and by bending the notch 23A formed on the side surface and hooking it on the frame 21, The prism sheets 6 and 7, the light diffusion sheet 22, the light guide plate 2, and the reflection sheet 27 are pressed to hold them in the frame 21. Further, the light guide plate cover 23 is formed with an opening 23B,
As a result, the overall weight is reduced, and screw holes for disposing the wiring board are formed around these openings 23B.

Similarly, the lamp cover 24 is formed by punching and bending a stainless steel plate material having a spring property, and the notch 24A formed on the side surface is bent and hooked on the frame 21 to form the light guide plate 2. With the tip protruding to the side, the primary light source 3 is covered and the primary light source 3 is held by the frame 21.

FIG. 1 is a cross-sectional view showing the primary light source 3 side in an enlarged scale by cutting FIG. 2 along the line BB. In the frame 21, after holding the edge of the reflector 25, which is a light reflection sheet, on the side of the emission surface by the double-sided tape 26, the fluorescent lamp 8 is arranged inside the reflector 25, whereby the primary light source 3 is arranged. In the frame 21, the prism sheet 6, the prism sheet 6, so that the reflector 25 and the prism sheets 6 and 7 do not overlap with each other and the emission surface 2C of the light guide plate 2 does not overlap with the reflector 25 on the exit surface 2C side. 7. The light guide plate 2 is laminated and held.

On the other hand, the light diffusing sheet 22 is formed so that the tip thereof projects toward the fluorescent lamp 8 side, so that the illumination light and the like incident on the end faces of the prism sheets 6 and 7 from the fluorescent lamp 8 are shielded, The uneven brightness caused by the illumination light and the like being observed from the emission surface 2C is reduced.

The reflector 25 has a property (so-called elasticity) of being repulsed when it is completely or imperfectly returned to its original shape by bending or the like, and its thickness is partially changed by a pressing force. It is formed of a white foamed PET sheet material (plate thickness 0.11 [mm]) and is arranged so as to surround the fluorescent lamp 8 from the emission surface 2C side. Furthermore, the tip of the reflector 25 is folded back on the side of the slope 2B, and the reflector 25 extends over the edge on the side of the incident surface 2A of the light guide plate 2 on the side of the slope 2B.
The lamp covers 24 overlap each other and are pressed by the lamp cover 24. In the lamp cover 24 that presses the reflector 25 in this manner, the entire light guide plate 2
Is formed so as to project to the slope side of the
Through the tip side of the reflector 25 that overlaps with each other,
The reflection sheet 27, the light guide plate 2 and the like are pressed against the opposing surfaces of the frame 21.

As a result, in this embodiment, the reflector 25 has the reflecting sheet 27, the light guide plate 2, and the light diffusing sheet 22 due to the elastic force of the double overlapped portion and the repulsive force of returning to the original portion of the bent portion. , The gap formed between the prism sheets 6 and 7, and further the frame 21.
The gap between the prism sheet 7 and the lamp cover 24 and the reflection sheet 27 is reduced, and light leakage caused by these gaps is effectively avoided.

In this embodiment, the reflector 25 is pre-processed so as to have a so-called habit at the bent portion, so that in this side light type surface light source device, the primary light source 3 can be easily and surely.
It is designed so that the sides can be assembled.

On the other hand, the reflection sheet 27 similarly has
A sheet material of white foamed PET (having a thickness of 0.18) that has elasticity to completely or incompletely return to its original shape when bent or the like, and whose thickness is partially changed by pressing force.
[Mm]), so that in this embodiment, three layers of the foamed elastic body are arranged on the incident surface 2A side of the light guide plate 2.

In the above-described structure, the illumination light emitted from the fluorescent lamp 8 (FIG. 1) enters the inside of the light guide plate 2 through the incident surface 2A directly or after being reflected by the reflector 25, and the illumination light is emitted. The light propagates inside the light guide plate 2 while being repeatedly reflected between the inclined surface 2B and the emission surface 2C. At this time, this illumination light is scattered by the light diffusing surface formed on the inclined surface 2B of the light guide plate 2, and the angle of incidence on the emission surface 2C gradually decreases as a whole when reflected by the inclined surface 2B.
A component having a critical angle or less with respect to the emission surface 2C is emitted from the emission surface 2C. The illumination light emitted from this emission surface 2C is
After passing through the light diffusion sheet 22, the prism sheets 6 and 7 sequentially correct the directivity. As a result, the liquid crystal panel or the like arranged on the front surface of the prism sheet 7 is illuminated.

In the light guide plate 2 which propagates and emits the illumination light in this way, the tip end is folded back and the reflector 25 and the reflection sheet 27, which are superposed in two layers,
Together with the light diffusion sheet 22 and the prism sheets 6 and 7, the lamp cover 24 presses and holds the frame 21. At this time, due to the elastic force in the thickness direction of the double-overlapped portion of the reflector 25, the repulsive force to return to the original portion of the bent portion, and the elastic force in the thickness direction of the reflection sheet 27, the light guide plate 2 is , The reflection sheet 27, the light guide plate 2, the light diffusion sheet 22, the prism sheets 6 and 7, and also between the frame 21 and the prism sheet 7 and between the lamp cover 24 and the reflection sheet 27. Also, even if the frame is sandwiched by the lamp cover 24 and the frame is narrowed, light leakage from these gaps can be effectively avoided.

In particular, in the foamed PET sheet material, since the thickness is partially changed by the pressing force, it is possible to fill even the gaps formed at the non-uniform intervals. When the reflector 25 and the reflection sheet 27 are made of a foamed PET sheet material and a slight undulation occurs on the slope of the light guide plate 2, the reflector 25 and the reflection sheet 27 are pressed by a member such as a wiring board arranged on the slope side. Even if the lamp cover 24 is deformed, light leakage can be effectively and surely avoided. Especially when narrowing the frame as in this embodiment,
It is also conceivable to reduce the thickness of the frame 21, and if the thickness of the frame 21 is reduced in this way, the dimensional accuracy of the frame 21 itself due to molding may deteriorate.
However, even in such a case, according to the foamed PET sheet material whose thickness is partially changed by the pressing force, it is possible to effectively avoid generation of a gap and prevent light leakage.

In addition to this, the lamp cover 2 is separated from the light guide plate cover 23 by an elastic metal plate material.
4 is formed, the light guide plate 2 due to various stresses applied when the sidelight type surface light source device is mounted,
It is possible to prevent the formation of gaps between the light diffusion sheets 22,
This also prevents light leakage.

Further, in the reflector 25, since the reflector 25 is arranged so as to overlap the edge of the light guide plate 2 on the incident surface 2A side in a doubled manner, the pressing force is concentrated at the portion corresponding to this edge, which also narrows the area. It is possible to effectively avoid light leakage when a frame is formed.

According to the above construction, the reflector 25 and the reflection sheet 27 are formed of a sheet material of foamed PET, and the tip of the reflector 25 is folded back to overlap the edge of the light guide plate 2 on the incident surface 2A side so as to be superposed. Further, since the light guide plate 2 and the like are sandwiched together with the frame 21 by being pressed by the lamp cover 24, it is possible to effectively avoid the generation of a gap between members such as the light guide plate 2 and the like, and thus even if the frame is narrowed, It is possible to effectively avoid light leakage from the gap. Therefore, it is possible to form a high-quality display image by applying the liquid crystal display device accordingly.

Further, at this time, since the reflector 25 and the reflection sheet 27 are formed by the sheet material of foamed PET, the thickness of which is partially changed by the pressing force, the respective thicknesses of the reflector 25 and the reflection sheet 27 are changed. Even if the gaps formed in the feeling of members are non-uniform, it is possible to fill the gaps, and it is possible to reliably prevent light leakage.

(2) Second Embodiment FIG. 3 is a sectional view showing a side light type surface light source device according to a second embodiment of the present invention in comparison with FIG. The sidelight type surface light source device 30 includes a frame 3
1 and the lamp cover 32 guide the fluorescent lamp 8 to the light guide plate 2
The frame 31 and the lamp cover 32 form a reflector. In the sidelight type surface light source device 30, the same configurations as those in the first embodiment are denoted by the corresponding reference numerals, and the duplicated description will be omitted.

That is, the frame 31 is formed of white resin and is formed in the same shape as the frame 21 according to the first embodiment. As a result, the frame 31 houses the light guide plate 2 and the like as well as the frame 21 according to the first embodiment, and in addition, can efficiently scatter and reflect the illumination light.

On the other hand, the lamp cover 32 is formed to have the same shape as the lamp cover 24 according to the first embodiment, and then the inner side is coated with white paint, whereby the reflection sheet 34 is formed. The light guide plate 2 is pressed and held therethrough, and the illumination light can be scattered and reflected efficiently in this state.

On the other hand, the reflection sheet 34 has the elasticity of returning to its original shape completely or incompletely when it is bent, and the thickness of the reflection sheet 34 is partially changed by the pressing force. Foamed PET sheet material (plate thickness 0.18 [m
m]), and its tip projects toward the fluorescent lamp 8 side. Further, the protruding portion of the reflection sheet 34 is folded back, and the reflection sheet 34 is overlapped in a double manner across the edge of the light guide plate 2 on the incident surface 2A side and pressed by the lamp cover 32, whereby the lamp cover 32 is formed.
Is configured to press the light guide plate 2 and the like against the facing surfaces of the frame 31 via the front end side of the reflection sheet 34 that is doubly overlapped.

According to the structure shown in FIG. 3, even if the reflection sheet 34 is folded back so as to overlap the edge of the light guide plate 2 on the side of the incident surface 2A and overlaps, and is pressed by the lamp cover 24, the first sheet is formed. The same effect as that of the embodiment can be obtained.

(3) Third Embodiment FIG. 4 is a sectional view showing a side light type surface light source device according to a third embodiment of the present invention in comparison with FIG. In this sidelight type surface light source device 40,
The same configurations as those in the first embodiment are denoted by the corresponding reference numerals, and the duplicate description will be omitted.

The side light type surface light source device 40 is accommodated in a separate frame-shaped frame after the primary light source is held on the light guide plate 2 by the lamp frame 41. That is, in this embodiment, the lamp frame 41 is formed by molding black resin into a U-shaped cross section, and
After being folded back and held by the light guide plate 2, the light guide plate 2 is arranged so as to be sandwiched by sliding from the side surface. Further, in the lamp frame 41, the fluorescent lamp 8 is inserted and held from the side surface in the space surrounded by the reflector 25 thereafter.

As shown in FIG. 4, the frame for holding the primary light source on the light guide plate 2 is formed in a U-shaped cross section, and the light guide plate 2 is formed.
Even if they are sandwiched, the same effect as that of the first embodiment can be obtained.

(4) Fourth Embodiment FIG. 5 is a sectional view showing a sidelight type surface light source device according to a fourth embodiment of the present invention in comparison with FIG. In this sidelight type surface light source device 50,
The same configurations as those in the first embodiment are denoted by the corresponding reference numerals, and the duplicate description will be omitted.

In this embodiment, the reflection sheet 51 is used.
Is formed of a white foamed PET sheet material, and the tip thereof is formed so as to largely project toward the fluorescent lamp 8 side.
Further, the reflection sheet 51 is folded in three so as to straddle the edge of the light guide plate 2 on the incident surface 2A side, and then the fluorescent lamp 8 is formed.
Surrounds, and the tip reaches the emission surface side and the inside of the frame 21,
Here, the double-sided tape 26 fixes the frame 21. Thus, in the sidelight type surface light source device 50, the reflection sheet 51 and the fluorescent lamp 8 are first arranged on the frame 21 to form a primary light source, and then the prism sheets 7 and 6, the light diffusion sheet 22, and the light guide plate 2 are formed. Are sequentially laminated and arranged, and then the reflection sheet 51 is arranged on the slope 2B of the light guide plate 2 to fix the lamp cover 24.

As shown in FIG. 5, even if the reflecting sheet is projected to serve also as the reflector and the reflecting sheet is folded back three times and pressed, the same effect as that of the first embodiment is obtained. Obtainable. Further, at this time, the reflector is also used as the reflecting sheet, so that the entire structure can be simplified accordingly.

(5) Fifth Embodiment FIG. 6 is a sectional view showing a side light type surface light source device according to a fifth embodiment of the present invention in comparison with FIG. In the mode, the reflection sheet 61 is further projected so that it is folded back across the edge of the light guide plate 2 even on the emission surface side.

As shown in FIG. 6, the reflection sheet 61 is also folded back over the edge of the light guide plate 2 on the exit surface side.
By arranging, the light leakage can be prevented more reliably as compared with the first embodiment.

(6) Other Embodiments In the above-described embodiments, the case where the reflection sheet or the reflector is folded back so as to straddle the edge of the light guide plate 2 has been described, but the present invention is not limited to this. Also, if the overlapping area of the light guide plate is sufficiently large, etc. and it is possible to prevent light leakage practically, it is not necessary to arrange it so as to straddle the edge in particular. 2 sheets or reflectors
You may arrange | position in three layers.

In the above embodiment, the case where the reflection sheet is made of foamed PET is described even when the reflector is folded back to prevent light leakage.
The present invention is not limited to this, and the reflective sheet may be made of a polyester film or the like when light leakage can be sufficiently prevented in practical use.

Further, in the above-described embodiment, the case where the reflector and the reflection sheet are formed by the foamed PET made of the white foamed sheet material has been described, but the present invention is not limited to this, and various white foamed sheet materials can be used. It can be widely applied, and not only the foamed sheet material but also various sheet materials whose thickness is partially changed by the pressing force can be widely applied.

Further, in the above-mentioned embodiment, the case where the reflector and the reflection sheet are formed by the sheet material whose thickness is partially changed by the pressing force has been described, but the present invention is not limited to this, and the gap is uniform. When light leakage can be sufficiently prevented in practice, such as when it is formed, the reflector and the reflection sheet are simply formed by an elastic sheet material that completely or imperfectly returns to its original shape when folded. Good.

Further, in the above-described embodiment, the case where the reflector and the reflection sheet are formed by the light scattering member made of white foamed PET has been described, but the present invention is not limited to this, and silver is formed on the surface of foamed PET, for example. The reflector and the reflection sheet may be formed by a regular reflection member to which a sheet or the like is attached. It is also possible to use a white (diffusive reflective) sheet that is not a foam, a sheet in which a base material is coated with white ink, or a specular reflective sheet.

Further, in the above-mentioned embodiment, the case where the end face of the reflector is abutted against the end face of the prism sheet and held at the exit face side has been described, but the present invention is not limited to this, and the side light type shown in FIG. 7 is used. Surface light source device 7
It can be widely applied to the case where the reflector 25 is arranged so as to partially overlap the prism sheet 7 as shown in FIG. Even if the reflector 25 is folded back at this overlapping portion, the same effect as in the above-described embodiment can be obtained.

Further, in the above-mentioned embodiment, the case where the prism sheets each having the prism surface formed on one surface thereof are laminated and arranged as the light control member has been described, but the present invention is not limited to this, and the two prism sheets are arranged. Instead, it is widely applied to the case where a double-sided prism sheet is arranged, the directionality is corrected only in one direction by one prism sheet, and the directionality is not corrected by removing the prism sheet. be able to.

Further, in the above-described embodiment, the case where the illumination light is incident from one end face has been described, but the present invention is not limited to this, and in addition, the side light type surface having the configuration in which the illumination light is incident from the other end face is also described. It can be widely applied to a light source device.

Further, in the above-described embodiment, the case where the plate thickness of the light guide plate is gradually reduced as the distance from the primary light source is described, but the present invention is not limited to this, and the light guide plate is formed with a substantially uniform plate thickness. It can also be widely applied when forming.

In the above-mentioned embodiments, the case where the rod-shaped light source is used as the primary light source has been described. However, the present invention is not limited to this, and the case where the primary light source is composed of a point light source such as a light emitting diode, or a plurality of such When arrayed to form a primary light source, it can be widely applied to a sidelight type surface light source device by various light sources.

Further, in the above-mentioned 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 it is a side light type such as various lighting devices and display devices. It can be widely applied to surface light source devices.

[0070]

As described above, according to the present invention, the light reflecting sheet that reflects the illumination light is formed of a sheet material having elasticity against bending, and the light reflecting sheet is arranged by folding back. By pressing the plate-shaped member through the overlapping and overlapping portions, it is possible to effectively avoid light leakage due to the gap between the holding member and various members.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a sidelight type surface light source device according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the overall configuration of FIG.

FIG. 3 is a cross-sectional view showing a sidelight type surface light source device according to a second embodiment of the present invention in comparison with FIG.

FIG. 4 is a cross-sectional view showing a sidelight type surface light source device according to a third embodiment of the present invention in comparison with FIG.

FIG. 5 is a cross-sectional view showing a sidelight type surface light source device according to a fourth embodiment of the present invention in comparison with FIG.

FIG. 6 is a cross-sectional view showing a sidelight type surface light source device according to a fifth embodiment of the present invention in comparison with FIG.

FIG. 7 is a cross-sectional view showing a sidelight type surface light source device according to another embodiment of the present invention in comparison with FIG.

FIG. 8 is an exploded perspective view showing a conventional side light type surface light source device.

FIG. 9 is a cross-sectional view of FIG. 8 cut along line AA.

10 is a cross-sectional view corresponding to FIG. 9 for explaining light leakage.

[Explanation of symbols]

1, 20, 30, 40, 50, 60, 70 Side light type surface light source device 2 Light guide plate 2A Incident surface 2B Slope 2C Exit surface 3 Primary light source 4, 27, 34, 51, 61 Reflective sheet 6, 7 Prism sheet 8 Fluorescent lamp 9,25 Reflector 10, 31, 41 Frame 24, 32 Lamp cover

Claims (6)

[Claims] 1. A side light type surface light source device in which illumination light is incident on the end face from a light source arranged on the end face of the plate-like member, and the illumination light is bent and emitted from an emission face of the plate-like member. A light reflection sheet that is arranged so as to surround the light source so as to form an opening toward the end surface, reflects the illumination light of the light source and guides the light to the end surface, and a holding member that holds the light reflection sheet near the end surface. And, the light reflection sheet is formed of a sheet material having elasticity against bending, and by the holding member, the tip portion of the light reflection sheet partially overlaps, and the overlapped portion is the It is characterized in that the light reflecting sheet is bent so as to overlap with the plate-like member and the light reflecting sheet is pressed, so that the plate-like member is pressed through the overlapped portion. Idoraito type surface light source device. 2. A side light type surface light source device in which illumination light is incident on the end face from a light source arranged on the end face of the plate-like member, and the illumination light is bent and emitted from the emission face of the plate-like member. A light reflection sheet that is disposed on a surface of the plate-shaped member that faces the emission surface and that reflects the illumination light leaking from the plate-shaped member to return to the plate-shaped member; and a holding member that holds the light source on the end face. And the light reflection sheet is formed by a sheet material having elasticity against bending so that the tip of the light reflection sheet protrudes toward the light source side, and the protruding portion of the light reflection sheet is partially formed by the holding member. By bending the protruding portion of the light reflection sheet and pressing the light reflection sheet so that the overlapped portion overlaps the plate-shaped member, Side light type surface light source device, characterized in that for pressing the plate-like member. 3. The light reflecting sheet according to claim 1, wherein the overlapped portion is arranged so as to straddle the edge of the end face.
A side light type surface light source device according to item 1. 4. The sidelight type according to claim 1, wherein the light reflection sheet is formed of a sheet material whose thickness is partially changed by a pressing force. Surface light source device. 5. The side light type surface light source device according to claim 4, wherein the light reflection sheet is formed of a white foam sheet material. 6. The holding member according to claim 1, wherein at least a part of the holding member is formed of an elastic metal plate material.
The side light type surface light source device according to claim 4 or 5.