JP2021034214A - Planar luminaire - Google Patents

Abstract

To provide a planar luminaire capable of performing fixing of an optical sheet stably even when a narrow framing is achieved.SOLUTION: A planar luminaire includes a light guide plate, a plurality of light sources, a spacer, and an optical sheet. The light guide plate allows light to enter from an incident side surface. The plurality of light sources irradiates the incident side surface of the light guide plate with the light. The spacer includes a comb tooth part arranged between adjacent light sources, and an eaves part extending on the light guide plate. In the plurality of optical sheets, an end part is fixed to the spacer. At the eaves part, recessed parts for accommodating the end parts of the optical sheets are provided both on an emission surface side and the opposite side from this.SELECTED DRAWING: Figure 3

Description

The present invention relates to a planar lighting device.

A so-called edge light type planar illumination device is known in which light is incident from the light entering side surface of the light guide plate and is emitted from one main surface of the light guide plate (see, for example, Patent Documents 1 to 3 and the like). ). The planar lighting device is used as a backlight or the like in a liquid crystal display device.

In a general planar lighting device, a top frame provided with an opening for light emission is often used as a part of a housing, and a portion of the top frame forming the opening for light emission is called a frame. Nowadays, there is a demand for narrowing the width of the frame, mainly from the viewpoint of design.

Further, in the planar lighting device, various optical sheets such as a diffusion sheet, a prism sheet, and a brightness improving sheet are laminated on the exit surface side of the light guide plate in order to adjust the brightness uniformity and the light distribution characteristics. The optical sheet is generally fixed to the peripheral edge of the light guide plate, a spacer, or the like.

Japanese Unexamined Patent Publication No. 2008-89944 Japanese Unexamined Patent Publication No. 2004-258460 Japanese Unexamined Patent Publication No. 2006-190521

However, due to the narrowing of the frame of the planar lighting device, the number of places for fixing the optical sheet is decreasing, and it is becoming difficult to stably fix the optical sheet. In particular, since the coefficient of linear expansion of the optical sheet differs depending on the material, the coefficient of linear expansion of the other party to be fixed and the fixing method may cause deterioration of the optical characteristics due to the occurrence of wrinkles, generation of rattle noise due to peeling of the fixation, and appearance. The influence of.

The present invention has been made in view of the above, and an object of the present invention is to provide a planar illumination device capable of stably fixing an optical sheet even when a narrow frame is achieved. ..

In order to solve the above-mentioned problems and achieve the object, the planar illumination device according to one aspect of the present invention includes a light guide plate, a plurality of light sources, a spacer, and an optical sheet. The light guide plate receives light from the side of the light entering. The plurality of light sources irradiate the light incoming side surface of the light guide plate with light. The spacer has a comb tooth portion arranged between the adjacent light sources and an eaves portion extending on the light guide plate. The ends of the plurality of optical sheets are fixed to the spacers. The eaves are provided with recesses for accommodating the end of the optical sheet on both the exit surface side and the opposite side.

The planar illumination device according to one aspect of the present invention can stably fix the optical sheet even when the frame is narrowed.

FIG. 1 is an external perspective view of the planar lighting device according to the embodiment. FIG. 2 is an exploded perspective view of the main components of the planar illuminator. FIG. 3 is a part (left side portion) of the XX cross-sectional view of the planar illuminator in FIG. FIG. 4 is a partial perspective view of the connection assisting portion. FIG. 5 is a perspective view of the spacer. FIG. 6 is a perspective view of the spacer from the opposite direction. FIG. 7 is a diagram showing an example of the shape of the light receiving side end portion of the light guide plate and the optical sheet. FIG. 8 is a diagram showing an end surface of the spacer on the optical sheet side.

Hereinafter, the planar lighting device according to the embodiment will be described with reference to the drawings. The present invention is not limited to this embodiment. In addition, the relationship between the dimensions of each element in the drawing, the ratio of each element, and the like may differ from reality. Even between drawings, there may be parts where the relationship and ratio of dimensions are different from each other. Further, in principle, the contents described in one embodiment or modification are similarly applied to other embodiments or modifications.

FIG. 1 is an external perspective view of the planar lighting device 1 according to the embodiment, and is a view seen from the light emitting surface side. In FIG. 1, for convenience of explanation, the direction along the long side of the housing of the planar lighting device 1 is the X-axis direction, the direction along the short side of the housing is the Y-axis direction, and the direction along the thickness of the housing. Is the Z-axis direction.

In FIG. 1, the planar lighting device 1 has a substantially rectangular shape (a substantially square shape is also possible) and a substantially plate-like outer shape, and the top frame 2B is exposed on the light emitting surface side on the front side in the drawing. There is. There is a bottom frame (2A) on the back side that cannot be seen in the figure. The top frame 2B is formed with an opening 2a that emits light inside. The portion around the opening 2a is a frame portion 2b. Further, a part of the light source substrate 5 is provided extending from the planar illumination device 1 in the positive direction of the X-axis, and a connecting portion 5a is provided at the tip thereof for electrical connection with the outside. Used. The top frame 2B is made of stainless steel sheet metal or the like. When the planar lighting device 1 is used as the backlight of the liquid crystal display device or the like, the liquid crystal display device or the like is mounted on the side of the opening 2a and the frame portion 2b.

FIG. 2 is an exploded perspective view of the main components of the planar lighting device 1, and is a view seen from the light emitting surface side as in FIG. 1. In FIG. 2, in the planar illumination device 1, a reflector 3A, a partial reflector 3B, a light guide plate 4, and optical sheets 7A to 7C are sequentially laminated on the bottom frame 2A on the upper side of the drawing, and the optical sheets 7A to 7C are laminated on the reflector 3A and the partial reflector 3B. The top frame 2B is arranged so as to cover the top frame.

The bottom frame 2A has a bottom portion and four side walls surrounding the bottom portion. The top frame 2B has a frame portion (2b) in which an opening (2a) is formed, and four side walls surrounding the frame portion.

The reflector 3A and the partial reflector 3B are arranged between the light guide plate 4 and the bottom of the bottom frame 2A, and reflect the light leaked to the surface opposite to the exit surface of the light guide plate 4 to be emitted to the exit surface side. It is an optical member. The partial reflector 3B is fixed to both the light guide plate 4 and the bottom frame 2A. The reflector 3A is not fixed to the light guide plate 4, but its end is fixed to the bottom frame 2A. Further, a gap (clearance) having a predetermined width required for assembly is provided between the reflector 3A and the partial reflector 3B.

The light guide plate 4 is an optical member that guides the light incident from the light incoming side surface 4a to the inside and emits the light from the main surface opposite to the reflector 3A. The light source substrate 5 and the spacer 6 are fixed to the bottom frame 2A on the light input side surface 4a side of the light guide plate 4. The light source substrate 5 is formed of an FPC (Flexible Printed Circuit) or the like. A plurality of (many) LEDs and other light sources 5b are arranged on the portion of the light source substrate 5 facing the light incoming side surface 4a. Although the illustrated example shows the case of a top-view type LED that emits light from the top surface, a side-view type LED that emits light from the side surface can also be used.

The ends of the optical sheets 7A to 7C (where the ears (tongue pieces) are appropriately formed) are fixed to the spacer 6. The optical sheet 7A is an optical member such as a diffusion sheet. The optical sheet 7B is an optical member such as a prism sheet or a BEF (Brightness Enhancement Film). The optical sheet 7C is an optical member such as a reflective polarizing film or a DBEF (Dual Brightness Enhancement Film).

FIG. 3 is a part (left side portion) of the XX cross-sectional view of the planar lighting device 1 in FIG. 1, and the upper direction of the figure is drawn as the light emission direction. In FIG. 3, on the inner surface of the bottom portion of the bottom frame 2A, one main part of the partial reflector 3B forming a part of the first portion of the reflector is interposed via a fixing member 101 such as a white and strongly adhesive double-sided tape. The surface and the main surface on the end side of the reflector 3A, which is the second portion of the reflector, are fixed in common. A connection assisting portion 102 is fixed to the main surface of the partial reflector 3B opposite to the fixing member 101. The reflector 3A is made of a material having bubbles inside, such as a biaxially stretched polyester film, while the partial reflector 3B is made of a material having no bubbles inside, such as PET (Polyethylene Terephthalate).

The main surface of the connection assisting portion 102 opposite to the partial reflector 3B is fixed to the main surface of the light guide plate 4 on the light inlet side surface 4a side. The main surface of the reflector 3A opposite to the fixing member 101 is not fixed to the light guide plate 4. A gap G, which is a clearance required for assembly, is provided between the first portion of the reflector and the second portion of the reflector.

FIG. 4 is a partial perspective view of the connection assisting portion 102. In FIG. 4, in the connection assisting portion 102, a strip-shaped base material 104 made of PET or the like in which a substantially rectangular notch 104a is formed is fixed on a strip-shaped fixing member 103 such as double-sided tape, and each notch 104a is fixed. Inside, a fixing member 105 such as a thermocompression bonding tape is fixed to the fixing member 103. The surface of the fixing member 103 opposite to the base material 104 is fixed to the partial reflector 3B. The surface of the fixing member 105 opposite to the fixing member 103 is fixed to the light guide plate 4.

The fixing member 105 is arranged in a flying island shape so as to be arranged between adjacent light sources 5b such as LEDs, and reduces the influence of total reflection on the optical identification on the contact surface between the fixing member 105 and the light guide plate 4. It is designed to let you. The notch 104a of the base material 104 functions as a flow stop when the fixing member 105 such as a thermocompression bonding tape melts, and secures an adhesive force by securing a predetermined adhesive area and thickness. Although the notch 104a has an opening at one end for ease of processing, it may be a hole surrounding the fixing member 105.

Returning to FIG. 3, the light source substrate 5 is fixed to the inner surface of the side wall of the bottom frame 2A via a fixing member 106 such as double-sided tape. The exit surface of the light source 5b on the light source substrate 5 faces the entrance side surface 4a of the light guide plate 4. Further, a spacer 6 is provided from between the light source substrate 5 and the light entrance side surface 4a of the light guide plate 4 to the end portion of the light guide plate 4 on the exit surface side.

FIG. 5 is a perspective view of the spacer 6, and FIG. 6 is a perspective view of the spacer 6 from the opposite direction. The directions of the coordinate axes in FIG. 5 are aligned with those in FIGS. 1 and 2. In FIGS. 5 and 6, the spacer 6 has a plurality of comb tooth portions 6a arranged between adjacent light sources 5b (FIG. 3) and a light source substrate 5 (FIG. 3) behind the plurality of comb tooth portions 6a. A connecting portion 6b that connects on the side) and an eaves portion 6c that bends and extends from the connecting portion 6b to the light guide plate 4 (FIG. 3) side. The comb tooth portions 6a do not have to be arranged between all the adjacent light sources 5b, and may be provided at every plurality of light sources 5b.

Further, the spacer 6 has a recess 6d to which the ear portion of the end portion of the optical sheet 7C is fixed, a recess 6f to which the ear portion of the end portion of the optical sheets 7A and 7B is fixed, and an ear portion of the end portion of the optical sheet 7A. It is provided with a recess 6 g to which the portion is fixed. Further, the spacer 6 is provided with a hole 6h in which the protrusion of the light guide plate 4 is engaged, substantially in the center. The spacer 6 and the light guide plate 4 are fixed by a flying island-shaped fixing member, and it is necessary to suppress the movement in the direction parallel to the light entering side surface 4a. However, the protrusion of the light guide plate 4 engages with the hole 6h of the spacer 6. Therefore, positioning can be easily performed.

Returning to FIG. 3, the light guide plate 4 side of the eaves portion 6c of the spacer 6 is attached to the light guide plate 4 by a flying island-shaped fixing member 107 (see FIG. 8) arranged near the middle of adjacent light sources 5b by using double-sided tape or the like. It is fixed. The tobishima-shaped fixing member 107 reduces the influence of total reflection on the optical identification on the contact surface between the fixing member 107 and the light guide plate 4. Since the spacer 6 and the light guide plate 4 are both made of resin or the like and have similar linear expansion coefficients, even if they are fixed to each other over the entire surface in the longitudinal direction of the spacer 6, the difference in the amount of expansion and contraction due to temperature change is large. It is small and the fixing member 107 does not come off. Further, the end portions of the optical sheets 7A to 7C are fixed to the eaves portion 6c of the spacer 6. Details of fixing the optical sheets 7A to 7C will be described later.

The top frame 2B is covered on the opening side of the bottom frame 2A, and the housing is formed by the bottom frame 2A and the top frame 2B. The portion of the gap G between the partial reflector 3B and the reflector 3A is in the dead area covered by the frame portion 2b of the top frame 2B, and the influence on the emitted light emitted from the opening 2a is reduced.

FIG. 7 is a diagram showing an example of the shapes of the light receiving side ends of the light guide plate 4 and the optical sheets 7A to 7C. Further, FIG. 8 is a diagram showing end faces of the spacer 6 on the optical sheets 7A to 7C side. One surface of the spacer 6 is fixed to the exit surface of the light guide plate 4 on the entrance side surface 4a side by a flying island-shaped fixing member 107.

In FIGS. 7 and 8, the selvage portion 7d at the end of the outermost optical sheet 7C is fixed to the recess 6d of the spacer 6 with double-sided tape or the like, and the selvage portion 7e further protruding from the ear portion 7d is the spacer 6. Engage in recess 6e (FIG. 5). Further, the thickness (total thickness) of the fixing member such as the optical sheet 7C and the double-sided tape is equal to the height of the recess 6d of the spacer 6 in the thickness direction, and the exit surface side of the spacer 6 is filled with the optical sheet 7C. It becomes a flat surface.

Further, the selvage portion 7c at the end of the optical sheet 7B and the selvage portion 7a at the end of the optical sheet 7A are overlapped and fixed with double-sided tape or the like in the recess 6f on the surface opposite to the exit surface of the spacer 6. Ru. The ear portion 7b at the end of the optical sheet 7A is fixed to the recess 6g of the spacer 6 with double-sided tape or the like. The thickness of the fixing member such as the optical sheets 7B, 7A and the double-sided tape is equal to the height of the recess 6f of the spacer 6 in the thickness direction, and the thickness of the fixing member such as the optical sheet 7A and the double-sided tape and the recess of the spacer 6 are equal to each other. The height in the thickness direction of 6 g is the same, and the side opposite to the exit surface of the spacer 6 is filled with optical sheets 7B and 7C to form a flat surface.

Since the spacer 6 and the optical sheets 7A to 7C are both made of resin or the like and have a close coefficient of linear expansion, even if they are directly fixed, the difference in the amount of expansion and contraction due to temperature changes is small, and the optical sheet 7A The occurrence of wrinkles in ~ 7C is reduced. Further, the optical sheets 7A to 7C are housed within the height of the spacer 6 on both the exit surface side and the surface on the opposite side thereof, which can contribute to the reduction in thickness. Further, since both the exit surface side and the opposite side of the spacer 6 are used for fixing the optical sheet, the height of the spacer 6 can be effectively used, which can contribute to further reduction in thickness.

In FIG. 7, the protrusion 4b provided at the substantially central portion of the light guide plate 4 engages with the hole 6h (FIG. 6) of the spacer 6 to facilitate positioning. Further, since the spacer 6 has an L-shaped curved structure, it also has a function of accurately maintaining the gap between the light guide plate 4 and the light source 5b.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

As described above, the planar illumination device according to the embodiment is arranged between a light guide plate that receives light from the light entrance side surface, a plurality of light sources that irradiate the light entrance side surface of the light guide plate, and adjacent light sources. A spacer having a comb tooth portion, an eave portion extending on a light source plate, and a plurality of optical sheets whose ends are fixed to the spacers, and the eaves portion is a recess for accommodating an end portion of the optical sheet. Is provided on both the exit surface side and the opposite side. As a result, the optical sheet can be stably fixed even when the frame is narrowed.

Further, the recessed portion of the eaves accommodates the end portion of the optical sheet in the cross section. This can contribute to the miniaturization of the planar lighting device.

Further, the spacer accommodates the end portion of the first optical sheet on the exit surface side of the eaves, and accommodates the end portions of the first and second optical sheets on the side opposite to the exit surface. As a result, the height of the spacer can be effectively used, which can contribute to further reduction in thickness.

Further, the light guide plate has a protrusion at a position close to the substantially central portion of the side surface of the light entering light, and the spacer has a positioning hole that engages with the protrusion. This makes it easy to position the light guide plate and the spacer.

Moreover, the present invention is not limited by the above-described embodiment. The present invention also includes a configuration in which the above-mentioned components are appropriately combined. Further, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

1 planar illuminator, 2A bottom frame, 2B top frame, 3A reflector, 3B partial reflector, 4 light guide plate, 4a light inlet side, 5 light source board, 5a connection, 5b light source, 6 spacer, 7A-7C optical sheet , 7a-7e Ear

Claims (4)

A light guide plate that receives light from the side of the light entry and
A plurality of light sources that irradiate the light incoming side surface of the light guide plate with light,
A spacer having a comb tooth portion arranged between the adjacent light sources and an eaves portion extending on the light guide plate.
A plurality of optical sheets whose ends are fixed to the spacer,
With
The eaves are provided with recesses for accommodating the end of the optical sheet on both the exit surface side and the opposite side.
Planar lighting device. The recess of the eaves accommodates the end of the optical sheet within the cross section.
The planar lighting device according to claim 1. The spacer accommodates the end portion of the first optical sheet on the exit surface side of the eaves, and accommodates the end portions of the first and second optical sheets on the side opposite to the exit surface.
The planar lighting device according to claim 1 or 2. The light guide plate has a protrusion at a position close to a substantially central portion of the side surface of the light entering light.
The spacer has a positioning hole that engages with the protrusion.
The planar lighting device according to any one of claims 1 to 3.

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