JP2016139601A - Planar light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently guide light emitted from a light emitting element to a light incident surface of a light guide plate, and to adapt with respect to expansion of the light guide plate.SOLUTION: A planar light source device 10 of the embodiment includes: a flat tabular light guide plate 11 having a light emission surface 11a and a light incident surface 11b orthogonal to and adjacent to the light emission surface 11a; a light emitting element 12a which is arranged so that a light emission surface 12b opposes a the light emission surface 11a at a predetermined interval, and which emits light toward the light emission surface 11a from the light emission surface 12b; a light diffusion sheet 14 arranged on the light emission surface 11a; and a reflection film 13 for covering a space between the light guide plate 11 and the light emitting element 12a. One end of the reflection film 13 is attached to an end part on the light incident surface 11b side of one of the light emission surface 11a of the light guide plate 11 and an opposing surface 14a of the light diffusion sheet 14 opposing the light guide plate 11, and the other end of the reflection film 13 is not attached to anything and it is arranged in the vicinity of an upper surface 12c adjacent to the light emission surface 12b of the light emitting element 12a.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a planar light source device, and more particularly to an edge light type planar light source device that illuminates a liquid crystal display panel or the like from its back surface.

  2. Description of the Related Art Conventionally, an edge light type surface light source device including a reflecting member that reflects light emitted from a light source and guides the light emitted from the light source to an incident end surface of a light guide plate is known. In Patent Document 1, a reflection sheet is provided so as to cover the periphery of a linear light source arranged in parallel with one side surface of the light guide plate.

  The end of the reflection sheet on the light exit surface side is superimposed on the light exit surface of the light guide plate and fixed by being covered with a transparent adhesive tape. It is described that the end of the reflection sheet side of the reflection sheet is bonded and fixed to the light diffusion sheet via a double-sided adhesive tape, or is not laminated by an adhesive tape or an adhesive only by laminating in this order. Yes.

  In patent document 2, the light emission surface side end of the light guide plate of the reflective film is bonded to the light emission surface of the light guide plate with a double-sided tape. The opposite end of the reflective film is adhered to the back surface of the light diffusing reflector disposed on the back side of the light guide plate with a double-sided tape, and the back surface of the light guide plate is covered with the light diffusive reflector through an air layer. It has been broken.

  In Patent Document 3, a reflector provided around a straight tube light source is divided into a first reflector portion located on the exit surface side and a second reflector portion located on the back surface side in the thickness direction of the light guide plate. ing. An inner end edge of the first reflector portion is attached to the frame body and is detachable from the light guide plate. The inner edge of the second reflector portion is sandwiched between the frame and the light diffusion plate, and is fixedly arranged with respect to the light guide plate. The lower end edges of the first and second reflector portions are configured to overlap in order to prevent light leakage from the reflector.

  Patent Documents 4, 5, and 6 describe a planar light source device that uses a light emitting diode (LED) as a light source. A reflective sheet is installed so as to cover the incident end face of the light guide plate and the upper face of the LED.

  In Patent Document 4, the reflection sheet is locked to a claw portion provided on a housing frame or the like, or fixed by an adhesive tape or the like so that the position of the reflection sheet does not move. In Patent Document 5, both ends of the reflection sheet are attached to the substrate on which the LED is mounted and the end portion of the light guide plate, respectively.

  In Patent Document 6, a reflective member whose shape can be deformed is provided so as to surround a space formed by the light emitting element array module and the light guide plate so that light from the light emitting element array module does not leak outside. In Patent Document 6, the support structure for the light guide plate and the structure for fixing the light emitting element array module are separate, and the light from the light emitting element array module is transmitted to the incident surface of the light guide plate even when the positions of both are shifted. Therefore, the reflecting member is fixed so as not to deviate from the above space.

Japanese Patent Laid-Open No. 08-190021 JP 05-341134 A JP 2003-323807 A JP-A-2005-243522 JP 2008-097999 A Japanese Patent Laid-Open No. 2007-041471

  In the planar light emitting device as described above, the light guide plate expands in the direction perpendicular to the thickness direction in particular due to a temperature rise inside the housing due to heat generated when the light source is driven, a rise in environmental temperature, moisture absorption, and the like. When the light guide plate expands, the light guide plate may come into contact with the light source disposed on the side of the light guide plate, which may cause damage to the light source or the light guide plate or drive failure of the light source. For this reason, a predetermined gap in consideration of expansion of the light guide plate is formed in advance between the light incident surface of the light guide plate and the light source.

  In the technique described above, one end of the reflection sheet is fixed to the light emitting surface of the light guide plate, and the other end is fixed to a light diffusion sheet, a housing, a substrate on which the LED is mounted, or the like. For this reason, when a light guide plate expand | swells and the clearance gap between a light guide plate and a light source shrinks, a reflective sheet interferes with another member, and shape changes, such as a bending of a light guide plate and a wave, generate | occur | produce. With the change in the shape of the light guide plate, there may be a problem of luminance uniformity and luminance reduction.

  In Patent Document 1, it is described that the end portion on the reflection surface side of the reflection sheet is not bonded, but the reflection sheet covers the linear light source, and the end portion on the reflection surface side is on the reflection surface of the light guide plate. Since it arrange | positions so that it may laminate | stack on the arrange | positioned light-diffusion sheet | seat, mounting of a reflection sheet is difficult.

  The present invention has been made to solve such problems, and can efficiently guide the light emitted from the light emitting element to the light incident surface of the light guide plate and adapt to the expansion of the light guide plate. An object of the present invention is to provide a possible planar light source device.

  The planar light source device according to the first aspect of the present invention includes a flat light guide plate having a light emitting surface, a light incident surface perpendicular to and adjacent to the light emitting surface, and a light emitting surface on the light incident surface. Are arranged so as to face each other with a predetermined interval, and emit light from the light exit surface toward the light incident surface, an optical sheet disposed on the light exit surface, and the light guide plate And a reflective film covering a space between the light emitting element, and one end of the reflective film is either the light emitting surface of the light guide plate or the facing surface of the optical sheet facing the light guide plate. It sticks to the edge part by the side of a light-incidence surface, and the other end of the said reflection film is not stuck to any, but is arrange | positioned in the vicinity of the upper surface adjacent to the said light emission surface of the said light emitting element.

  According to the present invention, it is possible to provide a planar light source device capable of efficiently guiding the light emitted from the light emitting element to the light incident surface of the light guide plate and adapting to the expansion of the light guide plate.

1 is a top view illustrating a configuration of a planar light source device according to Embodiment 1. FIG. It is a figure explaining the state at the time of normal temperature of the planar light source device which concerns on Embodiment 1. FIG. It is a figure explaining the state at the time of the high temperature of the planar light source device which concerns on Embodiment 1. FIG. It is a figure explaining the state at the time of normal temperature of the planar light source device which concerns on Embodiment 2. FIG. It is a figure explaining the state at the time of the high temperature of the planar light source device which concerns on Embodiment 2. FIG. FIG. 3 is a diagram illustrating a part of the configuration of the planar light source device according to the first embodiment. It is a figure which shows a part of structure of the planar light source device which concerns on Embodiment 3. FIG. It is a figure which shows a part of structure of the planar light source device which concerns on Embodiment 3. FIG.

  Hereinafter, embodiments will be described with reference to the drawings. In the following drawings, components having the same action are denoted by the same reference numerals. In addition, the dimensional relationship in each figure does not reflect the actual dimensional relationship.

Embodiment 1 FIG.
The planar light source device according to Embodiment 1 will be described with reference to FIGS. FIG. 1 is a top view showing the configuration of the planar light source device 10 according to the first embodiment. FIG. 2 is a diagram for explaining the state of the planar light source device 10 at normal temperature, and FIG. 3 is a diagram for explaining the state of the planar light source device 10 at high temperature. The planar light source device 10 is an edge light type planar light source device that illuminates a liquid crystal display panel or the like from its back surface.

  In order to facilitate understanding, in the following drawings, directions that are parallel to the light emitting surface 11a of the light guide plate 11 and are orthogonal to each other are defined as an x direction and a y direction. The x direction is the longitudinal direction of the light guide plate 11, and the y direction is the short direction of the light guide plate 11. The direction orthogonal to the light exit surface 11a of the light guide plate 11 is defined as the z direction. In the z direction, the side of the light guide plate 11 where the light diffusion sheet 14 and the microlens array sheet 15 are arranged is the light emission direction.

  As shown in FIG. 1, Embodiment 1 shows an example in which light source modules 12 are provided at both ends in the longitudinal direction (x direction) of the light guide plate 11, respectively. 2 and 3 are cross-sectional views on the side of one light source module 12 of the planar light source device 10 shown in FIG.

  As shown in FIGS. 1 to 3, the planar light source device 10 includes a light guide plate 11, a light source module 12, a reflection film 13, a light diffusion sheet 14, a microlens array sheet 15, a reflection sheet 16, a reflection member 17, and a support member 18. The circuit board 19 is provided. For the sake of explanation, optical sheets such as the light diffusion sheet 14 and the microlens array sheet 15 disposed on the upper surface of the light guide plate 11 are omitted in FIG.

  As shown in FIG. 1, the light guide plate 11 is a flat plate-like member having a light emitting surface 11a and a light incident surface 11b. The light incident surface 11b is adjacent to and orthogonal to the light emitting surface 11a. The light source module 12 includes a circuit board 19 and a plurality of light emitting elements 12a. For example, a light emitting diode (LED) or a semiconductor laser can be used as the light emitting element 12a.

  The circuit board 19 is an elongated rectangular board. A plurality of light emitting elements 12 a are mounted on the circuit board 19 along the longitudinal direction (y direction) of the circuit board 19. The plurality of light emitting elements 12a may be sealed with a transparent sealing resin (not shown). The light emitting element 12a is mounted on the circuit board 19 on the mounting surface 12d.

  As shown in FIG. 2, the light emitting surface 12b of the light emitting element 12a is disposed so as to face the light incident surface 11b. The light emitting element 12a emits light from the light exit surface 12b toward the light incident surface 11b. A predetermined interval is formed between the light exit surface 12b and the light incident surface 11b in consideration of the expansion of the light guide plate 11.

  The light guide plate 11 is a transparent member that guides light incident from the light incident surface 11b while reflecting the light from the upper surface (light emitting surface 11a) and the lower surface (optical surface 11c). The light guide plate 11 is made of a transparent resin such as PMMA (polymethyl methacrylate), PC (polycarbonate), PS (polystyrene), or the like.

  On the optical surface 11 c of the light guide plate 11, a minute optical pattern (not shown) having a dot shape is formed. The light guided through the light guide plate 11 enters the optical pattern, deviates from the total reflection condition by the optical pattern, and exits from the light exit surface 11 a of the light guide plate 11. A reflection sheet 16 is installed on the back side of the light guide plate 11. The reflection sheet 16 reflects light leaking from the lower surface of the light guide plate 11 and re-enters the light guide plate 11.

  In the first embodiment, the light diffusion sheet 14 and the microlens array sheet 15 are stacked in the z direction as an example of the optical sheet on the light emitting surface 11a of the light guide plate 11. The light diffusion sheet 14 has a function of diffusing light incident from the facing surface 14 a inside and emitting the light toward the microlens array sheet 15. As the light diffusion sheet 14, for example, a material in which scattering particles such as silica and styrene beads are dispersed in an optically transparent resin such as PET (polyethylene terephthalate), PP (polypropylene), and PC (polycarbonate) is used. it can. By dispersing the scattering particles in the transparent resin, it is possible to emit light that is uniform and has less luminance unevenness.

  A microlens pattern in which a plurality of hemispherical and convex microlenses are arranged at predetermined positions is formed on the upper surface of the microlens array sheet 15. The microlens array sheet 15 exhibits an optical refraction effect in which incident light is refracted and emitted so that the emitted light emitted toward the liquid crystal display panel has good viewing angle characteristics. Examples of the material of the microlens array sheet 15 include resins such as acrylic resin, epoxy resin, and polyimide.

  The optical sheet is not limited to the light diffusing sheet 14 and the microlens array sheet 15, and a plurality of conventionally known various types such as prism sheets can be used in a stacked arrangement. is there. Here, let the surface which opposes the light-guide plate 11 of the light-diffusion sheet 14 be the opposing surface 14a.

  When the thin light guide plate 11 having a flat plate shape is used as in the first embodiment, the height of the light source module 12 is larger than the thickness of the light incident surface 11 b of the light guide plate 11. For this reason, the upper surface 12c of the light source module 12 arranged facing the light incident surface 11b of the light guide plate 11 protrudes above the upper surface (light emitting surface 11a) of the light guide plate 11. In the first embodiment, the upper surface 12c is a surface facing the mounting surface 12d.

  As described above, when the light source module 12 protrudes above the upper surface of the light guide plate 11, all the light emitted from the light emitting element 12 a does not enter the light incident surface 11 b, and a part of the light is guided to the light guide plate 11. 11 leaks to the outside and the light utilization efficiency deteriorates.

  In order to solve this problem, as shown in FIG. 2, the reflective film 13 is disposed so as to cover the space between the light guide plate 11 and the light emitting element 12a. The reflective film 13 reflects light in the visible light region that does not enter the light incident surface 11b out of the light emitted from the light emitting element 12a, and guides it to the light incident surface 11b.

  As shown in FIG. 1, the reflective film 13 is an elongated strip-shaped member. As the reflective film 13, for example, a film coated with silver or aluminum, or an ESR (Enhanced Specular Reflector) reflective film manufactured by 3M, which is a multilayer film, can be used.

  The length of the reflective film 13 in the longitudinal direction (y direction) is formed according to the length of the light guide plate 11 in the short direction (y direction). One end along the longitudinal direction of the reflective film 13 is attached to the end of the light exit surface 11a of the light guide plate 11 on the light incident surface 11b side by an adhesive member (not shown) such as a double-sided tape or an adhesive. .

  On the other hand, the other end along the longitudinal direction of the reflective film 13 is not attached to either. As shown in FIG. 2, at the normal temperature, the other end of the reflective film 13 is disposed in the vicinity of the upper surface 12c adjacent to the light exit surface 12b of the light emitting element 12a. As shown in FIG. 3, when the temperature is higher than that at room temperature, the light guide plate 11 expands toward the light source module 12 as indicated by the solid arrow. In this case, since the other end of the reflection film 13 is not fixed to any of them, the other end of the reflection film 13 protrudes from the upper surface 12 c to the opposite side to the light guide plate 11 as the light guide plate 11 expands.

  Thus, even when the light guide plate 11 expands due to a temperature change or the like and the gap between the light guide plate 11 and the light source module 12 is reduced, the reflective film 13 does not interfere with other members. As a result, it is possible to suppress the occurrence of a shape change such as deflection or undulation of the light guide plate, and it is possible to prevent luminance uniformity and luminance deterioration.

  As described above, in Patent Document 1, one end of the reflection sheet is disposed on the upper surface of the light guide plate and the other end is disposed so as to cover the back of the light guide plate so as to cover the periphery of the linear light source. On the other hand, in the first embodiment, the other end of the reflection film 13 is disposed in the vicinity of the upper surface 12 c of the light source module 12. For this reason, mounting of the reflective film 13 becomes easy.

  Further, on the optical surface 11c side of the light guide plate 11, a reflecting member 17 is provided between the light incident surface 11b of the light guide plate 11 and the light exit surface 12b of the light emitting element 12a. As the reflecting member 17, for example, the same member as the reflecting film 13 can be used. The reflection member 17 is supported by the support member 18. The space between the light guide plate 11 and the light source module 12 is surrounded by the reflective film 13 and the reflective member 17. Thereby, the utilization efficiency of the light emitted from the light emitting element 12a can be further increased.

  In Embodiment 1, it is preferable that the thermal expansion coefficient of the reflective film 13 is substantially equal to the thermal expansion coefficient of the light guide plate 11 to which the reflective film 13 is attached. As the reflective film 13, for example, a film obtained by vapor-depositing silver or aluminum on the same resin as the light guide plate 11 such as PMMA is suitably used. Thereby, it can prevent that the reflective film 13 peels from the light-guide plate 11. FIG.

  Furthermore, in Embodiment 1, the reflective film 13 is comprised with the member which can be elastically deformed. Thereby, when the light guide plate 11 expands / contracts and the light incident surface 11b moves in the direction approaching the light source module 12 side or in the direction moving away from the light source module 12 side, the reflection film 13 becomes the light diffusion sheet 14 or the light source module. Even when it contacts other members such as 12, the reflective film 13 itself is easily deformed. Thereby, the shape change of the light guide plate 11 can be further suppressed. According to the first embodiment, it is possible to realize a planar light source device with high luminance and high luminance uniformity.

Embodiment 2. FIG.
A planar light source device according to Embodiment 2 will be described with reference to FIGS. FIG. 4 is a diagram illustrating a state of the planar light source device 10 at a normal temperature, and FIG. 4 is a diagram illustrating a state of the planar light source device 10 at a high temperature. 4 and 5, the same reference numerals are given to the same components as those described above, and the description thereof is omitted. In addition, the figure which looked at the planar light source device 10 from the upper surface is the same as FIG.

  As shown in FIG. 4, in the second embodiment, one end along the longitudinal direction of the reflection film 13 is attached to the end of the light incident surface 11 b side of the facing surface 14 a of the light diffusion sheet 14. On the other hand, the other end along the longitudinal direction of the reflective film 13 is not attached to either. As shown in FIG. 4, at the normal temperature, the other end of the reflective film 13 is disposed in the vicinity of the upper surface 12c adjacent to the light exit surface 12b of the light emitting element 12a.

  As shown in FIG. 5, when the temperature is higher than that at normal temperature, the light guide plate 11 expands toward the light source module 12 as indicated by the solid arrow. In Embodiment 2, since the reflective film 13 is stuck to the light diffusion sheet 14, even if the light guide plate 11 expands, the position of the reflective film 13 does not change. Therefore, even at a high temperature, the other end of the reflective film 13 is disposed in the vicinity of the upper surface 12c adjacent to the light exit surface 12b of the light emitting element 12a.

  Thus, also in Embodiment 2, even when the light guide plate 11 expands and the gap between the light guide plate 11 and the light source module 12 is reduced, the reflective film 13 does not interfere with other members. Thereby, generation | occurrence | production of the shape change of a light-guide plate can be suppressed, and it becomes possible to prevent a brightness | luminance uniformity and a fall of a brightness | luminance.

  In Embodiment 2, it is preferable that the thermal expansion coefficient of the reflective film 13 is substantially equal to the thermal expansion coefficient of the light diffusion sheet 14 to which the reflective film 13 is attached. As the reflective film 13, for example, a film obtained by vapor-depositing silver on the same resin as the light diffusion sheet 14, such as PET, is preferably used. Thereby, it can prevent that the reflective film 13 peels from the light-diffusion sheet 14. FIG.

Embodiment 3 FIG.
In Embodiment 1, the light emission surface 11a to which the reflective film 13 of the light guide plate 11 is attached is flat. As shown in FIG. 6, the light traveling in the light guide plate 11 is totally reflected at the portion where the reflection film 13 of the light emitting surface 11 a of the light guide plate 11 is not attached. On the other hand, in the portion where the reflection film 13 of the light emitting surface 11a of the light guide plate 11 is attached by the attachment member 20, the light traveling in the light guide plate 11 is scattered.

  As described above, in the configuration in which the reflective film 13 is bonded to the light guide plate 11 side, the light in the light guide plate 11 is scattered throughout the portion of the light guide plate 11 where the sticking member 20 is in contact, and light is used. It causes a decrease in efficiency. Therefore, the inventor efficiently improves the light utilization efficiency in a configuration that efficiently guides the light emitted from the light source into the light guide plate and adapts to the expansion of the light guide plate as in the above-described embodiment. I devised a configuration to let you.

  Hereinafter, the planar light source device according to Embodiment 3 will be described with reference to FIGS. 7 and 8 are diagrams illustrating a part of the configuration of the planar light source device according to the third embodiment. In Embodiment 3, a plurality of semi-cylindrical lenses (see FIG. 8) extending in the x direction are arranged in the y direction as uneven portions on the light emitting surface 11a (see FIG. 7) of the light guide plate 11. A lenticular lens 11d is formed.

  An adhesive member 20 is disposed between the lenticular lens 11d and the reflective film 13. The adhering member 20 adheres the light guide plate 11 and the reflective film 13 only in the vicinity of the tip of the lenticular lens 11d. Thus, in Embodiment 3, one end of the reflective film 13 is attached to the end of the light exit surface 11a of the light guide plate 11 on the light incident surface 11b side at the convex portion of the uneven portion of the light exit surface 11a. . Thereby, since the area of the sticking member 20 which contacts the light-guide plate 11 can be made small, scattering of the light by the sticking member 20 can be prevented, and it becomes possible to suppress the reduction of light utilization efficiency.

  It should be noted that other configurations such as the light source module 12 can employ the same configurations as those in the first embodiment. As a result, the light emitted from the light source can be efficiently guided into the light guide plate, adapted to the expansion of the light guide plate, and the light utilization efficiency can be further improved.

  Instead of the lenticular lens 11d formed on the light exit surface 11a of the light guide plate 11, a trapezoidal prism shape or a triangular prism shape uneven portion may be formed. Moreover, you may form the uneven | corrugated | grooved part of polygonal shapes, such as a pentagon and a heptagon, in cross-sectional shape.

  In general, a surface of the light guide plate 11 opposite to the light exit surface 11a is formed with a dot shape that changes the angle of light. Such dot shapes include a convex shape that can be formed using an inkjet technique or the like, and a concave shape that can be formed using a laser processing technique or the like. In the planar light source device according to Embodiment 3, the light guide plate 11 having the dot shape is turned over on the surface opposite to the light emitting surface 11a, and the surface having the dot shape may be used as the light emitting surface 11a. . That is, such a dot shape can also be used as the concavo-convex portion (surface on which the sticking member 20 is stuck) described above.

  As described above, according to the embodiment, of the light emitted from the light emitting element 12a, the light having a large emission angle and not incident on the light incident surface 11b is guided to the light incident surface 11b by the reflection film 13. It becomes possible, and the utilization efficiency of light can be improved. Moreover, even when the light guide plate 11 expands and the distance between the light guide plate 11 and the light source module 12 decreases, the reflective film 13 does not interfere with other members, so that the shape change of the light guide plate 11 can be prevented.

  Moreover, when the uneven | corrugated | grooved part is formed in the light-projection surface 11a of the light-guide plate 11, the scattering of the light by the sticking member 20 can be suppressed, and it becomes possible to further improve the utilization efficiency of light.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Planar light source device 11 Light guide plate 11a Light emission surface 11b Light incident surface 11c Optical surface 11d Lenticular lens 12 Light source module 12a Light emitting element 12b Light emission surface 12c Upper surface 12d Mounting surface 13 Reflective film 14 Light diffusion sheet 14a Opposing surface 15 Micro lens array Sheet 16 Reflective sheet 17 Reflective member 18 Support member 19 Circuit board 20 Adhering member

Claims (9)

A flat light guide plate having a light exit surface and a light entrance surface adjacent to and orthogonal to the light exit surface;
A light emitting element that is disposed so that a light exit surface faces the light incident surface with a predetermined interval, and emits light from the light exit surface toward the light incident surface;
An optical sheet disposed on the light exit surface;
A reflective film covering a space between the light guide plate and the light emitting element;
With
One end of the reflective film is attached to an end of the light incident surface side of either the light emitting surface of the light guide plate or the facing surface of the optical sheet facing the light guide plate,
The other end of the reflective film is not attached to either, and is disposed in the vicinity of the upper surface adjacent to the light exit surface of the light emitting element.
A planar light source device. The reflective film is elastically deformable,
The planar light source device according to claim 1. The light guide plate further has an optical surface facing the light emitting surface,
On the optical surface side, the light guide plate further includes a reflecting member disposed between the light incident surface of the light guide plate and the light output surface of the light emitting element,
The reflective film and the reflective member surround a space between the light guide plate and the light emitting element;
The planar light source device according to claim 1 or 2. A circuit board on which a plurality of the light emitting elements are mounted;
The upper surface is a surface facing a mounting surface mounted on the circuit board of the light emitting element.
The planar light source device according to claim 1. The reflective film is attached to the light exit surface of the light guide plate,
The reflective film is made of a material having substantially the same thermal expansion coefficient as the light guide plate.
The planar light source device according to claim 1. The other end of the reflective film is located on the upper surface at normal temperature and protrudes from the upper surface to the opposite side of the light guide plate at a high temperature higher than that at normal temperature.
The planar light source device according to claim 5. The reflective film is attached to the facing surface of the optical sheet,
The reflective film is made of a material having substantially the same thermal expansion coefficient as the optical sheet.
The planar light source device according to claim 1. The other end of the reflective film is located on the upper surface at a normal temperature and at a high temperature higher than the normal temperature.
The planar light source device according to claim 7. Further comprising a concavo-convex portion formed on the light emitting surface,
One end of the reflective film is attached to the light incident surface side end of the light exit surface of the light guide plate in the convex portion of the uneven portion,
The planar light source device according to claim 1.

Images