JP2013206803A - Edge light type planar light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an edge light type planar light-emitting device in which a total amount of luminous flux of light emitted from an emitting surface of a light guide plate is increased and occurrence of luminance unevenness is suppressed.SOLUTION: An edge light type planar light-emitting device includes at least a resin-made light guide plate of a plan-view rectangular shape, a light source arranged along at least one of the end faces opposed to each other of the light guide plate, a substrate which is arranged opposed to the end face of the side where the light source is arranged and to which the light source is fixed, a housing body which surrounds the substrate, the light source, and the light guide plate, and a frame body of which a center part on the surface opposed to the light guide plate is open, and which surrounds the housing body from the light-emitting surface side of the light guide plate to cover a periphery edge of the light guide plate. Two or more reflection sheets are installed superimposed between the light guide plate and the housing body so that the end faces in a direction along the substrate may not be in contact with each other.

Description

  The present invention relates to an edge light type surface light emitting device. This surface light-emitting device is useful for lighting bodies used in indoors such as offices, vehicles such as bullet trains, refrigerators, etc., backlight units used in liquid crystal displays, signboards, and the like.

  The edge light type surface light emitting device generally includes at least a light source, a light guide plate for surface emitting light incident from the light source, and a housing body that surrounds and supports the light source and the light guide plate.

  In the edge light type surface light emitting device, the light source is disposed along the end surface of the light guide plate, and the light emitted from the light source enters the light guide plate from the end surface where the light source of the light guide plate is disposed, and is further guided. Reflected within the light plate and emitted from the light exit surface of the light guide plate. The light that has entered the light guide plate may be emitted not only from the light output surface of the light guide plate, but also from the surface opposite to the light output surface (reflection surface). Therefore, as shown in Patent Document 1, for the purpose of reflecting the light emitted from the reflecting surface and returning it back into the light guide plate, a reflecting sheet is provided on the entire surface of the housing body facing the reflecting surface. There is. By providing the reflection sheet, it is possible to increase the total amount of light emitted from the light exit surface of the light guide plate.

JP 2006-201210 International Publication No. 2011/092902

  When the edge light type surface light emitting device is turned on, the light source generates heat, and the temperature in the vicinity of the light source rises. The edge light type surface light emitting device may be used in a high temperature environment or a high humidity environment. Since the reflective sheet is a foamed resin sheet or a resin sheet formed by metal vapor deposition on the surface, it may be bent due to thermal expansion or hygroscopic expansion depending on the heat generated from the light source or the temperature and humidity of the usage environment. . Luminance unevenness may occur on the light emitting surface of the edge light type surface light emitting device due to the bending generated in the reflection sheet, which is a problem.

  In order to improve such a problem, Patent Document 2 reports that a plurality of long hole portions are provided in the reflection sheet so that the major axis direction of the long hole portions is along the direction in which the reflection sheet thermally expands. ing. However, in this method, it is necessary to confirm in advance the direction in which the reflective sheet thermally expands, and by providing a long hole in the reflective sheet surface, the light reflection efficiency decreases, and the light output from the light guide plate is reduced. There is a possibility that the total luminous flux of the light emitted from the surface is reduced.

  Accordingly, an object of the present invention is to provide an edge light type surface light emitting device in which the total luminous flux of light emitted from the light exit surface of a light guide plate is increased and the occurrence of luminance unevenness is suppressed.

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.

That is, the present invention relates to the following inventions.
(1) A resin-made light guide plate having a rectangular shape in plan view, a light source disposed along at least one end face of the light guide plate facing each other, and disposed opposite to the end face on the side where the light source is disposed, A substrate on which the light source is fixed, a housing body that surrounds the substrate, the light source and the light guide plate, and a central portion of a surface facing the light guide plate is an opening, and the light guide plate covers the periphery of the light guide plate A frame body that surrounds the housing body from the light exit surface side, and the light from the light source is incident on the end surface of the light guide plate on the side where the light source is disposed and reflected within the light guide plate, thereby the light exit surface. In the edge light type surface light emitting device that emits light from the light source, the two or more reflective sheets are overlapped between the light guide plate and the housing body so that the edges in the direction along the substrate do not contact each other. It is characterized by being provided Edge-light type surface light emitting apparatus.
(2) The edge light type surface emitting device according to (1), wherein the size of the reflection sheet is smaller than the size of the side surface of the light guide plate of the housing body.
(3) Of the two or more reflective sheets, the edge of the reflective sheet provided on the light guide plate side does not exist in the perpendicular region of the central portion of the frame body (1) or (2 ).
(4) The edge light type surface emitting device according to any one of (1) to (3), wherein a reflective sheet is provided between a side surface of the housing body of the light source and a side surface of the light guide plate of the housing body.

  In the invention of (1), two or more reflecting sheets are provided so as to overlap between the light guide plate and the housing body so that the edges in the direction parallel to the substrate do not contact each other. The total amount of light emitted from the light exit surface of the light guide plate can be increased, and the occurrence of uneven brightness can be suppressed.

  In the invention of (2), since the dimension of the reflection sheet is smaller than the dimension of the side surface of the light guide plate of the housing body, the occurrence of the deflection of the reflection sheet can be further suppressed.

  In the invention of (3), among the two or more reflective sheets, the edge of the reflective sheet provided on the light guide plate side is not present in the perpendicular region of the central portion of the frame body. Generation of bright lines can be suppressed.

  In the invention of (4), since the reflection sheet is provided between the surface orthogonal to the surface fixed to the substrate of the light source and the housing body, the total luminous flux of the light emitted from the light output surface of the light guide plate The amount can be increased further.

It is sectional drawing of the edge light type surface emitting device of one Embodiment of this invention. It is sectional drawing of the edge light type surface emitting device of another one Embodiment of this invention. It is sectional drawing of the conventional edge light type surface emitting device. It is sectional drawing of the other conventional edge light type surface emitting device.

  FIG. 1 is a cross-sectional view of an edge light type surface light emitting device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of an edge light type surface emitting device according to another embodiment of the present invention. The surface light emitting device 1 includes at least a light guide plate 2, a light source 3, a housing body 4, a frame body 5, and a reflection sheet 6.

  The light guide plate 2 is a rectangular plate in plan view and is made of resin as a main component. As the resin, for example, at least one selected from the group consisting of (meth) acrylic resin, polystyrene resin, polyolefin resin, polycarbonate resin, polyvinyl chloride resin, and (meth) acrylic acid ester-styrene resin is preferable, Particularly preferred is a (meth) acrylic resin. These resins may be used as a mixture of two or more, or may be used so as to laminate two or more. The thickness of the light guide plate 2 is usually 1 to 10 mm, preferably 2 to 8 mm, and more preferably 2.5 to 5 mm. If the light guide plate 2 is too thin, light from the light source 3 may be difficult to enter. If the light guide plate 2 is too thick, the light emission efficiency may be insufficient, and the weight of the entire surface light emitting device is heavy. Therefore, it is not preferable that it is too thin or too thick.

  An irregular reflection layer 20 is formed on the reflection surface 2 </ b> W of the light guide plate 2. The irregular reflection layer 20 is formed by subjecting the reflective surface 2W to direct processing with a laser in the form of dots or stripes, screen printing or vapor deposition of ink, or ink jet printing. . The irregular reflection layer 20 is preferably in the form of dots from the viewpoint of suppressing occurrence of luminance unevenness in the surface light emitting device. Examples of the form of the dot include a substantially circular shape, a substantially triangular shape, a substantially rectangular shape, and a substantially hexagonal shape. As a method of forming the irregular reflection layer 20 in a dot shape, (1) a method of applying unevenness to the portion corresponding to the dot or attaching ink or the like, and (2) a portion of the ground other than the dot On the other hand, there is a method of performing uneven processing or attaching ink or the like. The method (1) is referred to as “positive pattern”, and the method (2) is referred to as “negative pattern”. In the case of a positive pattern, the dot distribution is preferably such that the area occupied by the dots per unit area gradually increases as the distance from the end face on the side where the light source is arranged. It is preferable that the area occupied by the dots per unit area gradually decreases as the distance from the end face on the side where the light source is disposed.

  A light diffusing plate 7 can be provided on the light exit surface 2X side of the light guide plate 2. The light diffusing plate 7 is a plate having a rectangular shape in plan view, and is a plate having a light diffusing function or a light collecting function. The light diffusing plate 7 is a plate made of a resin composition containing a light diffusing agent, a plate made of a resin composition and having a concavo-convex shape on the surface, a resin composition containing a light diffusing agent and concavo-convex on the surface. It is composed of a plate having a shape or a plate made of resin and coated with a light diffusing agent on the surface. The resin constituting the light diffusion plate 7 is, for example, selected from the group consisting of (meth) acrylic resin, polystyrene resin, polyolefin resin, polycarbonate resin, polyvinyl chloride resin, and (meth) acrylic acid ester-styrene resin. At least one type is preferable, and a (meth) acrylic resin is particularly preferable. These resins may be used as a mixture of two or more, or may be used so as to laminate two or more. Examples of the light diffusing agent to be included in the light diffusing plate or coated on the surface of the plate include organic fine particles such as acrylic crosslinked beads and (meth) methyl acrylate-styrene copolymer (MS) crosslinked beads. Inorganic fine particles such as silica, titanium oxide, and barium sulfate can be used, and among them, organic fine particles are preferable. These light diffusing agents may be used as a mixture of two or more. The thickness of the light diffusing plate 7 is usually 500 μm to 5 mm, preferably 1 to 3 mm. If the light diffusing plate 7 is too thin, if the surface light emitting device may be distorted, the light diffusing plate 7 is likely to be wrinkled or broken. If it is too thick, the weight of the entire surface light emitting device is increased. Since it becomes heavy, it is not preferable that it is too thin or too thick. Further, a protective plate (not shown) having a rectangular shape in plan view may be provided on the light exit surface side of the light diffusion plate 7.

  A plurality of light sources 3 are arranged along the opposite end faces 21 and 22 of the light guide plate 2. Examples of the light source 3 include an LED, a fluorescent lamp, and a cold cathode tube. Among these, an LED is preferable.

  The light source 3 only needs to be disposed along at least one of the opposing end surfaces of the light guide plate 2, and may be disposed along the opposing end surfaces 21 and 22 of the light guide plate 2. 21 and 22 may be arranged along one of the end faces.

  The light sources 3 are fixed to the substrate 30 at equal intervals. The substrate 30 is disposed to face the light guide plate end surfaces 21 and 22 on the side where the light source is disposed, and the surface opposite to the surface on which the light source is fixed is fixed to the side surface portion of the housing body. Is preferred. When the light source 3 is disposed only along one of the end surfaces 21 and 22, the substrate 30 is disposed to face only the end surface on the side where the light source 3 is disposed.

A spacer (not shown) may be provided on the substrate 30 between the adjacent light sources 3 along with the light sources 3. By making the thickness of the spacer in the direction orthogonal to the substrate surface larger than the same thickness of the light source 3, the end surface of the light guide plate 2 facing the substrate 30 abuts on the spacer and does not abut on the light source 3. Since the end surface of the light guide plate 2 does not contact the light source 3, even if an impact is applied to the light guide plate 2, the impact is not directly transmitted to the light source 3.
The spacer is usually a plate made of resin. The resin constituting the spacer is preferably a transparent resin having a high light transmittance or a white resin having a high light reflectance in order to efficiently use light emitted from the light source to the light guide plate. .

  The housing body 4 includes a main body surface portion 41 that covers the light guide plate 2 from the reflective surface 2W side, and four side surface portions 421, 422 that extend from the four sides of the main body surface portion 41 so as to cover the end surface of the light guide plate 2. 423 and 424 and arranged so as to surround the substrate 30, the light source 3 and the light guide plate 2. In FIG. 1, only the main body surface portion 41 and the side surface portions 421 and 423 are shown.

  The frame body 5 includes a main body surface portion 51 that covers the light guide plate 2 from the light exit surface 2X side, and four side surface portions 521 and 522 that are extended from the four sides of the main body surface portion 51 so as to cover the side surface portion of the housing body 4. 523, 524, and is disposed so as to surround the housing body 4 from the light exit surface 2X side of the light guide plate. Here, the frame body 5 has an opening at the center portion of the main body surface portion 51, which is a surface facing the light guide plate 2, and surrounds the housing body 4 from the light guide plate side so as to cover the peripheral portion of the light guide plate 2. Is arranged. The central portion of the main body surface portion 51 has an opening serving as a light emitting surface of the edge light type surface light emitting device. In FIG. 1, only the main body surface portion 51 and the side surface portions 521 and 523 are shown.

  Two or more reflective sheets 6 are provided between the light guide plate 2 and the housing body 4 so as to overlap each other. These two or more reflective sheets 6 are stacked so that the edges in the direction along the substrate do not contact each other. By providing the reflection sheet 6 in this way, it is possible to increase the total amount of light emitted from the light exit surface 2X of the light guide plate 2 and to suppress the occurrence of luminance unevenness.

  As the reflection sheet 6, for example, a polyester film or a film made of glass or plastic on which a metal having a high reflectance such as silver is evaporated can be used. The thickness of the reflection sheet 6 is usually 50 μm to 1 mm.

The reflective sheet 6 preferably has a dimension smaller than the dimension of the side surface (bottom surface 4X) of the light guide plate of the main body surface portion 41 of the housing body 4, and all of the reflective sheets 6 provided between the light guide plate 2 and the housing body 4 are used. It is preferable that the dimension is smaller than the dimension of the bottom surface 4X of the housing body 4. As shown in FIG. 1, when the substrate 3 is in contact with the side surface portions 421 and 423 of the housing body 6 and the substrate 3 is also in contact with the main body surface portion 41 of the housing body 4, the size of the reflection sheet 6 is It is preferable to make it smaller than the dimension obtained by subtracting the dimension of the portion where the substrate 30 is in contact with the bottom surface 4X from the dimension of the bottom surface 4X of the housing body 4.
By making the size of the reflecting sheet 6 smaller than the size of the bottom surface 4X of the housing body 4, even if the reflecting sheet 6 expands, the end sides of the reflecting sheet 6 do not come into contact with the side surfaces of the housing body and Occurrence of the accompanying deflection can be suppressed, and the occurrence of luminance unevenness can be further suppressed. The size of the reflection sheet 6 may be set from the thermal expansion coefficient, the hygroscopic expansion coefficient of the base material constituting the reflective sheet, the thermal expansion coefficient of the base material constituting the housing body, the hygroscopic expansion coefficient, and the like.

  Of the two or more reflective sheets 6, the edge of the reflective sheet 6 provided on the light guide plate side is an area in the direction perpendicular to the central portion of the main body surface 51 of the frame body 5 (see FIG. 2). It may be present in a region surrounded by a dotted line), but it is preferably not present in the region as shown in FIG. In this way, by preventing the end side from being present in the region in the normal direction of the central portion of the main body surface portion 51 of the frame body 5, generation of bright lines can be suppressed.

  A reflection sheet is preferably provided between the housing body side surface 3 </ b> W, which is the surface of the light source 3 that faces the body surface portion 41 of the housing body 4, and the body surface portion 41 of the housing body 4. By providing the reflection sheet in this way, it is possible to further increase the total amount of light emitted from the light exit surface of the light guide plate.

  In the edge light type surface light emitting device 1 having the above-described configuration, the light emitted from the light source 3 enters the light guide plate 2 from the end surfaces 21 and 22, and repeats reflection in the light guide plate 2 while repeating the reflection of the irregular reflection layer 20. The light is diffusely reflected at the dots and reflected by the reflective film 6 between the dots, and is diffused and emitted from the light exit surface 2X by the light diffusion plate 7. That is, the light exit surface 2X emits light by the light emitted from the light source 3. Thereby, the edge light type surface light-emitting device 1 exhibits a surface light-emitting function. The surface light-emitting device 1 having the above configuration has a sufficient illuminance, and is particularly suitable as an indoor lighting device.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

[Example 1]
2 is an edge light type surface light emitting device 1 having the configuration of FIG. The specific configuration of each part is as follows.
Light guide plate 2: A (meth) acrylic resin plate having a product name “Sumipex E005” manufactured by Sumitomo Chemical Co., Ltd. was used. The dimensions are 5 mm in thickness, 290 mm in width, and 290 mm in length. “SUMIPEX” is a registered trademark of Sumitomo Chemical Co., Ltd.
Diffuse reflection layer 20: formed by screen-printing reflective ink on the reflective surface 2 W of the light guide plate 2. The reflective ink is composed of volatile curable resin ink, acrylic beads, silica fine particles, and phosphor. The print pattern is a positive pattern, the dot shape is substantially circular, and the dot pitch (center-to-center distance) is constant. The irregular reflection layer 20 has a printing density per unit area that is small in the vicinity of the side end surfaces 21 and 22 of the light guide plate 2 and increases toward the center of the light guide plate so that the luminance of the surface light emitting device is substantially uniform. Is set.
-Light source 3: 42 LEDs manufactured by Nichia Corporation were fixed on the substrate 30 arranged opposite to the end faces 21 and 22, respectively, at regular intervals. The substrate 30 is fixed to the side surface portions 421 and 423 of the housing body 4 and is in contact with the main body surface portion 41. The distance from the side surface parts 421 and 423 to the light guide plate 2 side surface of the light source 3 is 5 mm, respectively.
Housing body 4: A box made of aluminum material was used. The dimensions of the bottom surface 4X of the housing body are a width of 300 mm and a length of 300 mm.
Frame body 5: Aluminum material processed into a box shape was used. The inner surface 5W of the main body surface 51 of the frame body 5 has a width of 302 mm and a length of 302 mm, and the opening of the central portion has a width of 280 mm and a length of 280 mm.
Reflective sheet 6: Reflective sheets 6A, 6B, and 6C having a product name “E60” manufactured by Toray Industries, Inc. were used. The dimensions of the reflection sheets 6A and 6B are 10 mm in width and 290 mm in length, and the dimensions of the reflection sheet 6C are 290 mm in width and 290 mm in length. The reflection sheets 6A and 6B are arranged so that the long side edge of the sheet and the substrate 30 are in contact with each other, and the distance between the short side edge and the side surfaces 422 and 424 of the housing body is 5 mm. It was installed between the housing body 5. The reflection sheet 6C has a distance of 5 mm between each end side and the side surface parts 421 to 424 of the housing body 4 facing the end side, and the reflection sheet 6C is on the light guide plate 2 side. Between the light guide plate 2 and the housing body 5, the reflective sheets 6 </ b> A and 6 </ b> B were placed so that 6 </ b> A and 6 </ b> B were on the housing body 4 side.
-Light diffusion plate 7: The product name “Sumipex EM090” manufactured by Sumitomo Chemical Co., Ltd. was used. The dimensions are 1.5 mm in thickness, 300 mm in width, and 300 mm in length.

[Example 2]
It is the edge light type surface emitting device 1 which has the structure of FIG. The reflective sheet 6 is the same as the edge light type surface light emitting device 1 of Example 1 except that it is as described later.
Reflective sheet 6: Reflective sheets 6D and 6E having a product name “E60” manufactured by Toray Industries, Inc. were used. The reflection sheets 6D and 6E have a width of 250 mm and a length of 290 mm. The reflection sheets 6D and 6E are such that the long side edge of the sheet is in contact with the substrate 30, and the distance between the short side edge and the side surfaces 422 and 424 of the housing body is 5 mm, respectively. Is disposed between the light guide plate 2 and the housing body 5 so that the reflection sheet 6E is on the housing body 4 side. At this time, the end of the reflecting sheet 6D opposite to the end on the long side contacting the substrate 30 is present in the perpendicular region of the central portion of the main body surface 51 of the frame body 5.

[Comparative Example 1]
It is the edge light type surface emitting device 1 which has the structure of FIG. The reflective sheet 6 is the same as the edge light type surface light emitting device 1 of Example 1 except that it is as described later.
Reflective sheet 6: A reflective sheet 6F having a product name “E60” manufactured by Toray Industries, Inc. was used. The reflection sheet 6F has a width of 290 mm and a length of 290 mm. The reflection sheet 6F is disposed between the light guide plate 2 and the housing body 5 so that the distance between each end side and the side surface portions 421 to 424 of the housing body 4 facing the end side is 5 mm. . At this time, no reflection sheet is provided between the housing body side surface 3 </ b> W of the light source 3 and the main body surface portion 41 of the housing body 4.

[Comparative Example 2]
It is the edge light type surface emitting device 1 which has the structure of FIG. The reflective sheet 6 is the same as the edge light type surface light emitting device 1 of Example 1 except that it is as described later.
Reflective sheet 6: A reflective sheet 6G having a product name “E60” manufactured by Toray Industries, Inc. was used. The reflection sheet 6G has a width of 300 mm and a length of 300 mm. The reflection sheet 6G is arranged between the light guide plate 2 and the housing body 5 so that each end side is in contact with the side surface parts 421 to 424 of the housing body 4 facing the end side.

[Performance evaluation]
(1) Measurement of total luminous flux The edge light type surface light emitting devices 1 of Examples 1 and 2 and Comparative Examples 1 and 2 are each a large integrating sphere for measuring the total luminous flux (model 1500 type spherical luminous meter manufactured by Nemtech Co., Ltd.). Installed in the center. Next, 12 W of electric power was applied to emit light, and the total luminous flux was measured with a diode array spectrometer (DAS-2100 manufactured by Labsphere). The results are shown in Table 1.

(2) Luminance unevenness evaluation The edge light type surface light emitting devices 1 of Examples 1 and 2 and Comparative Examples 1 and 2 were caused to emit light by applying 12 W of power in a room with an air temperature of 23 ° C. and a humidity of 55%. When the light emitting surface of the surface light emitting device 1 is visually observed after 300 hours have elapsed, when the luminance unevenness is not confirmed on the light emitting surface, “◯”, and when the luminance unevenness is confirmed on the light emitting surface Was determined as “×”. The results are shown in Table 1.

(3) Bright line evaluation The edge light type surface light-emitting devices 1 of Examples 1 and 2 and Comparative Examples 1 and 2 are caused to emit light by applying power of 12 W, and the light-emitting surface of the surface light-emitting device 1 is visually observed. The case where no bright line was confirmed on the light emitting surface was determined as “◯”, and the case where a bright line was confirmed on the light emitting surface was determined as “×”. The results are shown in Table 1.

  DESCRIPTION OF SYMBOLS 1 Edge light type surface emitting device 2 Light guide plate 3 Light source 30 Substrate 4 Housing body 5 Frame body 6A, 6B, 6C, 6D, 6E, 6F, 6G Reflective sheet 7 Light diffusion plate

Claims (4)

A resin-made light guide plate having a rectangular shape in plan view;
A light source disposed along at least one of the opposing end faces of the light guide plate;
A substrate disposed opposite to the end surface on the side where the light source is disposed, to which the light source is fixed;
A housing body surrounding the substrate, the light source and the light guide plate;
The central portion of the surface facing the light guide plate is an opening, and includes at least a frame body that surrounds the housing body from the light output surface side of the light guide plate so as to cover the peripheral edge of the light guide plate,
In the edge light type surface light emitting device, the light of the light source is incident from the end surface on the side where the light source of the light guide plate is disposed, reflected in the light guide plate and emitted from the light exit surface.
An edge light type surface light emitting device, wherein two or more reflection sheets are provided between a light guide plate and a housing body so that end sides in a direction along the substrate do not contact each other.   The edge light type surface emitting device according to claim 1, wherein a dimension of the reflection sheet is smaller than a dimension of a side surface of the light guide plate of the housing body.   The edge light of Claim 1 or 2 in which the edge of the reflection sheet provided in the light-guide plate side among two or more reflection sheets does not exist in the area | region of the perpendicular direction of the said center part of a frame body. Mold surface light emitting device.   The edge light type surface emitting device according to claim 1, wherein a reflection sheet is provided between a side surface of the housing body of the light source and a side surface of the light guide plate of the housing body.

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