JP2012123933A - Edge light type surface light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an edge light type surface light-emitting device capable of improving light-emitting efficiency by eliminating a gap between an end face of a light guide plate and a light source.SOLUTION: In the edge light type surface light-emitting device 1 including a resin light guide plate 2 with a rectangular shape in plane view, the light source 3 arranged along opposite end faces 2A, 2B of the light guide plate 2, and a housing body 4 surrounding the light source 3 and the light guide plate 2 and emitting light of the light source 3 from an emitting surface 2Y of the light guide plate 2 while it is incident from the end faces 2A, 2B of the light guide plate 2 and it is reflected in the light guide plate 2, the edge light type surface light-emitting device has a sandwiching mechanism 5 for sandwiching the light guide plate 2 from both end faces 2A, 2B sides. The sandwiching mechanism 5 for sandwiching the light guide plate 2 from both end faces 2A, 2B sandwiches the light guide plate 2 while pushing the light source 3 to the end faces 2A, 2B, and its sandwiching interval can be expanded and contracted in response to expansion and contraction of the light guide plate 2.

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 indoors in offices or in vehicles such as bullet trains, 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 surrounding and supporting the light source and the light guide plate. As the light guide plate, a resin plate such as (meth) acrylic resin is typically used.

JP 2010-177077 A JP-A-6-186433 JP 2006-185724 A

  By the way, since the light guide plate is made of resin, it expands due to heat from the light source and changes in temperature and humidity under the usage environment. Therefore, conventionally, in consideration of expansion of the light guide plate, a gap for absorbing the expansion is secured in advance between the light guide plate and the light source and / or between the light guide plate and the housing body. It was.

  However, when a gap is secured between the light guide plate and the light source in advance, a part of the light from the light source leaks out of the light guide plate, which causes a problem that the light emission efficiency is low. Further, when a gap is secured in advance between the light guide plate and the housing body, there is a problem that the light guide plate is unstable in the housing body and the light guide plate or the light source may be damaged.

  An object of the present invention is to provide an edge light type surface light emitting device capable of solving both the above-mentioned problems.

  The present invention includes at least 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 the housing, and a housing body surrounding the light source and the light guide plate. In the edge light type surface light emitting device, the light of the light source is incident on the end face of the light guide plate, reflected in the light guide plate, and emitted from the light exit surface of the light guide plate. A sandwiching mechanism sandwiching from the side, the sandwiching mechanism sandwiches the light guide plate while pressing the light source against the end face, and the sandwiching interval expands or contracts as the light guide plate expands and contracts. It is characterized by that.

  In addition, it is preferable that the said pinching mechanism has the following structures, for example. That is, it consists of two plate members and an elastic member, and the said plate member consists of a vertical plate part and a horizontal plate part, and a vertical plate part is provided along the said end surface of a light-guide plate. The horizontal plate portion is provided to extend to the front of the center of the reflection surface of the light guide plate, and the elastic member connects the horizontal plate portions of the two plate members at the center of the reflection surface of the light guide plate. The sandwiching mechanism is configured to sandwich the light guide plate by pulling the two plate members toward each other by the elastic member, and with the expansion and contraction of the light guide plate by the elastic force of the elastic member. Thus, the sandwiching interval is expanded or reduced.

  Furthermore, as the elastic member, specifically, for example, it is preferable to use a spring, a rubber string, or the like.

According to the present invention, the following effects can be exhibited.
(1) In the present invention, since the light source is pressed against the end face of the light guide plate by the sandwiching mechanism, there is no gap between the end face and the light source. Therefore, the light emitted from the light source enters the end face more efficiently than when there is a gap. Therefore, according to the present invention, the light emission efficiency of the light guide plate can be improved.

(2) In the present invention, when the light guide plate expands, the pinching interval of the pinching mechanism increases accordingly, and the expansion of the light guide plate is absorbed by the pinching mechanism. Therefore, even when the light guide plate is expanded, the light guide plate is maintained in a state of being sandwiched by the sandwiching mechanism and is stably held in the housing body. Therefore, according to the present invention, it is possible to prevent the light guide plate and the light source from being damaged by the expansion of the light guide plate.

(3) In the present invention, even when the light guide plate expands, the light source is pressed against the end face by the pinching mechanism. Therefore, even if the light guide plate expands, the light emitted from the light source efficiently enters the end face. Therefore, according to the present invention, the light emission efficiency of the light guide plate can be maintained even when the light guide plate expands.

It is sectional drawing of the edge light type surface emitting device of one Embodiment of this invention. It is a top view of the pinching mechanism of FIG.

  FIG. 1 is a cross-sectional view of an edge light type surface light emitting device according to an 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, and a pinching mechanism 5.

  The light guide plate 2 is a rectangular plate in plan view. A plurality of light sources 3 are arranged along the long side end faces 2A, 2B of the light guide plate 2 facing each other. The light source 3 is fixed on the substrate 30. As the light source 3, an LED, a fluorescent lamp, a cold cathode tube or the like can be used, and in particular, an LED can be preferably used.

  The light guide plate 2 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, the light from the light source 3 may be difficult to be incident. If the light guide plate 2 is too thick, the light emission efficiency may be insufficient. Is too heavy, so it is not preferable that it is too thin or too thick.

  An irregular reflection layer 21 is formed on the reflection surface 2 </ b> X of the light guide plate 2. The irregular reflection layer 21 is formed by subjecting the reflective surface 2X to direct processing with a laser in a dot shape or a stripe shape, screen printing or vapor deposition of ink, or ink jet printing. Yes. In particular, a dot shape is preferable. As the form of the dots, for example, a substantially circular shape, a substantially square shape, a substantially hexagonal shape, and the like are preferable. As a method of forming the irregular reflection layer 21 in the form of dots, (1) a method of applying unevenness to the portion corresponding to the dots or attaching ink or the like, and (2) a portion of the ground other than the dots 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 from the end faces 2A and 2B toward the center. In the case of a negative pattern, It is preferable that the area occupied by dots per unit area gradually decreases from the end faces 2A and 2B toward the center.

  A reflective film 22 is further provided on the surface of the irregular reflection layer 21. The thickness of the reflective film 22 is usually 50 to 400 μm. As the reflective film 22, for example, a low-foamed film made of white polyester, a film made of glass or plastic, and a metal having a high reflectance deposited thereon can be used.

  A light diffusing plate 23 is installed on the light exit surface 2Y of the light guide plate 2. The light diffusing plate 23 is made of resin as a main component and contains a light diffusing agent. 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. As the light diffusing agent, organic fine particles such as acrylic cross-linked beads and (meth) acrylic acid methyl styrene copolymer (MS) cross-linked beads, and inorganic fine particles such as silica, titanium oxide, and barium sulfate are used. Can be used, and two or more of these may be used simultaneously. In particular, organic fine particles are preferable. Similar to the light guide plate 2, the light diffusion plate 23 may be a rectangular plate in plan view. The thickness is usually about 0.1 to 5 mm, preferably 0.15 to 4 mm. If the light diffusing plate 23 is too thin, wrinkles are likely to occur in the light diffusing plate 23 itself. If the light diffusing plate 23 is too thick, the entire surface light emitting device becomes heavy. It is not preferable. Further, a clear protective plate (not shown) having a rectangular shape in plan view is installed on the light exit surface side of the light diffusing plate 23 so as to cover the light diffusing plate 23 in order to suppress generation of wrinkles of the light diffusing plate 23. Is preferred.

  The housing body 4 is configured to surround and support the light guide plate 2, the light source 3, and the sandwiching mechanism 5.

  The sandwiching mechanism 5 sandwiches the light guide plate 2 from both end surfaces 2A and 2B while pressing the light source 3 against the end surfaces 2A and 2B, and with the expansion and contraction of the light guide plate 2, The sandwiching interval W is expanded or reduced.

  FIG. 2 is a plan view of the pinching mechanism 5 of FIG. Specifically, the sandwiching mechanism 5 includes two plate members 51 and 52 and an elastic member 53. As the elastic member 53, a spring is used. The plate member 51 includes a vertical plate portion 511 and a horizontal plate portion 512. The vertical plate portion 511 is provided along the end surface 2 </ b> A of the light guide plate 2. The horizontal plate portion 512 is provided to extend to the near side of the center of the reflection surface 2X of the light guide plate 2. Similarly, the plate member 52 includes a vertical plate portion 521 and a horizontal plate portion 522. The vertical plate portion 521 is provided along the end surface 2 </ b> B of the light guide plate 2. The horizontal plate portion 522 is provided so as to extend to the front of the center of the reflection surface 2X of the light guide plate 2. The elastic member 53 connects the horizontal plate portion 512 and the horizontal plate portion 522 at the center of the reflective surface 2X of the light guide plate 2. In FIG. 2, the elastic member 53 connects the horizontal plate portion 512 and the horizontal plate portion 522 at two locations, but this is merely an example, and the number and positions of the connection locations are as shown in FIG. 2. It is not limited to this example, and is set as appropriate. Specifically, the elastic member 53 has one end connected to a hook 513 provided on the horizontal plate portion 512 and the other end connected to a hook 523 provided on the horizontal plate portion 522. Thus, the pinching mechanism 5 is configured to pinch the light guide plate 2 by pulling the plate member 51 and the plate member 52 together by the elastic member 53, and by the elastic force of the elastic member 53, the light guide plate With the expansion and contraction 2, the sandwiching interval W is expanded and contracted. In addition, the board | substrate 30 with which the light source 3 was fixed is attached inside the vertical board part 511,521. Therefore, the sandwiching mechanism 5 sandwiches the light guide plate 2 while pressing the light source 3 against the end surfaces 2A and 2B.

  The housing body 4 supports the light guide plate 2 and the sandwiching mechanism 5 by the upward support portion 41 and the downward support portion 42 so as to be gripped from above and below. Thereby, the light guide plate 2 is stably supported in the housing body 4, and the pinching mechanism 5 is maintained in a horizontal state.

  In the 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 surface 2A and the end surface 2B, and is diffusely reflected by the dots of the irregular reflection layer 21 while being repeatedly reflected in the light guide plate 2. In addition, between the dots, the light is reflected by the reflective surface 2X and the reflective film 22, and is diffused and emitted from the light exit surface 2Y by the light diffusion plate 23. That is, the light exit surface 2Y emits light by the light emitted from the light source 3. Thereby, the surface emitting device 1 exhibits a surface 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.

  By the way, in the surface light emitting device 1 having the above-described configuration, the light source 3 is pressed against the end surfaces 2 </ b> A and 2 </ b> B of the light guide plate 2 by the sandwiching mechanism 5. Therefore, there are no gaps between the end surface 2A and the light source 3 and between the end surface 2B and the light source 3. Therefore, the light emitted from the light source 3 enters the end faces 2A and 2B more efficiently than when there is a gap. Therefore, the light emission efficiency by the light guide plate 2 can be improved.

  On the other hand, the light guide plate 2 expands due to heat from the light source and changes in temperature and humidity under the usage environment. However, in the surface light emitting device 1 having the above-described configuration, when the light guide plate 2 expands in the direction of arrow A, the elastic member 53 extends so that the sandwiching interval W increases accordingly. That is, the expansion of the light guide plate 2 is absorbed by the elastic member 53. Therefore, even when the light guide plate 2 is expanded, the light guide plate 2 is maintained in a state of being sandwiched by the sandwiching mechanism 5 and is stably held in the housing body 4. Therefore, the light guide plate 2 and the light source 3 can be prevented from being damaged by the expansion of the light guide plate 2. Moreover, even when the light guide plate 2 expands, the light source 3 is pressed against the end surfaces 2A and 2B by the sandwiching mechanism 5. Therefore, even if the light guide plate 2 expands, the light emitted from the light source 3 efficiently enters the end faces 2A and 2B. Therefore, even when the light guide plate 2 expands, the light emission efficiency of the light guide plate 2 can be maintained.

The surface light emitting device 1 having the above configuration may adopt the following modified configuration.
(1) The light source 3 may be provided only on one of the end surfaces 2A and 2B of the light guide plate 2.
(2) As the elastic member 53, for example, a rubber string or the like other than the spring may be used.

[Example 1]
It is the surface emitting device 1 which has the structure 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 3 mm in thickness, 250 mm in width, and 600 mm in length. “SUMIPEX” is a registered trademark of Sumitomo Chemical Co., Ltd.
-Diffuse reflection layer 21: formed by printing a reflective ink by a screen printing method. The reflective ink is composed of volatile curable resin ink, acrylic beads, silica fine particles, and phosphor. The print pattern is a negative pattern, the dot shape is substantially circular, and the dot pitch (center-to-center distance) is constant. The negative pattern is set so that the printed portion per unit area is small near the light source and increases toward the center so that the luminance when used as illumination is uniform.
Reflective film 22: The product name “E60” manufactured by Toray Industries, Inc. was used.
-Light diffusion plate 23: The product name “GM7” manufactured by Kimoto Co., Ltd. was used. The thickness is 180 μm. Furthermore, an acrylic resin plate having a product name “SUMIPEX E000” manufactured by Sumitomo Chemical Co., Ltd. was used as a clear protective plate. The thickness is 1.5 mm.
LED: 84 pieces are arranged on each of the long side end faces 2A and 2B of the light guide plate 2 respectively.
In the first embodiment, the LED is pressed against the end surfaces 2A and 2B by the sandwiching mechanism 5, so that there is no gap between the LED and the end surfaces 2A and 2B.

[Comparative Example 1]
Only the point which does not have the pinching mechanism 5 is different from the first embodiment. In Comparative Example 1, a gap of 1.1 mm is provided between the LED and the end faces 2A and 2B.

[performance test]
The surface light-emitting device 1 of Example 1 was installed at the center of a large integrating sphere for measuring total luminous flux. Then, the surface light emitting device 1 was caused to emit light by applying power of 37.6 W, and the total luminous flux was measured by a diode array spectroscope.
For the surface light emitting device of Comparative Example 1, the total luminous flux was measured in the same manner.
The results are shown in Table 1.
As a large integrating sphere for measuring the total luminous flux, a model 1500 type spherical luminous meter manufactured by Nemtech Co., Ltd. was used. As a diode array spectrometer, DAS-2100 manufactured by Labsphere was used.

  As is clear from Table 1, the surface light emitting device 1 of Example 1 is excellent in luminous efficiency.

  Since the edge light type surface light emitting device of the present invention can follow the expansion of the light guide plate, the industrial utility value is great.

  DESCRIPTION OF SYMBOLS 1 Edge light type surface emitting device 2 Light guide plate 2A, 2B End surface 3 Light source 4 Housing body 5 Clamping mechanism 51, 52 Plate member 511, 521 Vertical plate portion 512, 522 Horizontal plate portion 53 Elastic member

Claims (3)

A resin-made light guide plate having a rectangular shape in plan view;
A light source disposed along at least one end surface of the opposing end surfaces of the light guide plate;
A housing body surrounding the light source and the light guide plate;
In the edge light type surface light emitting device, the light of the light source is incident from the end face of the light guide plate, reflected in the light guide plate and emitted from the light exit surface of the light guide plate.
It has a pinching mechanism that sandwiches the light guide plate from both end face sides,
The sandwiching mechanism is configured to sandwich the light guide plate while pressing the light source against the end surface, and the sandwiching interval is expanded and contracted as the light guide plate expands and contracts.
An edge light type surface light emitting device characterized by the above. The pinching mechanism is
It consists of two plate members and an elastic member,
The plate member is composed of a vertical plate portion and a horizontal plate portion,
The vertical plate portion is provided along the end face of the light guide plate,
The horizontal plate portion is provided to extend to the front near the center of the reflection surface of the light guide plate,
The elastic member connects the horizontal plate portions of the two plate members at the center of the reflection surface of the light guide plate,
The sandwiching mechanism is configured to sandwich the light guide plate by pulling the two plate members toward each other by the elastic member, and the sandwiching mechanism with the expansion and contraction of the light guide plate by the elastic force of the elastic member. The interval is designed to expand and contract,
The edge light type surface emitting device according to claim 1. The elastic member is a spring;
The edge light type surface emitting device according to claim 2.

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