JP2011243552A - Plane light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plane light-emitting device capable of maintaining a state in which a constant distance is set between a light guide plate and a reflecting plate against internal dew condensation or water infiltrated from outside.SOLUTION: The plane light-emitting device is provided with a light source, a light-source mounting substrate on which the light source is mounted, a light guide plate guiding light from the light source to an irradiating face, a reflecting plate reflecting light from the light guide plate, a light source case radiating heat of the light-source mounting substrate, and a frame for retaining them above. A spacer member is arranged between the light guide plate and the reflecting plate in order to maintain a constant gap between them.

Description

  The present invention relates to an edge light type surface light emitting device using a light guide plate, and relates to a surface light emitting device used as a backlight for indoor / outdoor signboards, indoor / outdoor advertising boards and indoor / outdoor guide boards.

The conventional edge light type surface light emitting device in which light is incident from the side surface of the light guide plate and irradiated on the front surface has a structure in which the light guide plate and the reflection plate are overlapped with each other.
However, when water such as rainwater permeates when the surface light emitting device is used outdoors, water flows from the end portions of the light guide plate and the reflector toward the center of the surface due to the capillary phenomenon that occurs because the gap between the light guide plate and the reflector is narrow. Sometimes got in.
Due to this phenomenon, the light bending rate of the portion containing water changes, and the unevenness of light that the portion where water has entered becomes brighter than the portion where water does not enter is generated. Due to the unevenness of the light, there is a problem that the color of the display board having the pattern is uneven due to the intensity of the light.
In order to solve this problem, a constant gap is formed between the light guide plate and the reflection plate so as to reduce the rise to the wall surface even if water enters from outside or a capillary phenomenon occurs as in Patent Document 1. As described above, a structure having a structure for holding both ends is disclosed. Further, a surface light emitting device is disclosed in which a water-stopping material is provided over the entire circumference between the frame and the display surface as in Patent Document 2, and is sealed so that water and moisture from the outside cannot be put inside. .

JP 2009-181012 A JP 2006-11101 A

However, when the structure in which the light guide plate and the reflection plate are held at a fixed interval only by a frame body as in Patent Document 1 is used for a large edge light type surface light emitting device, when the plate thickness of the light guide plate is thin, it depends on wind pressure. When an external force is applied to the surface of the light guide plate, the portion that is far from the frame holding the gap between the light guide plate and the reflection plate, that is, the center portion is bent, so the gap between the light guide plate and the reflection plate is It is extremely narrow compared to the gaps at both ends being held, and sometimes it is in close contact. At this time, water that has been infiltrated from the outside or condensed water that has occurred inside, for example, if the condensation is in the entire light guide plate, the water stays gathered together in the center due to capillary action, so the part where the water stayed As a result, unevenness of light occurs. In order to solve this problem, if the thickness of the light guide plate is increased as a measure for preventing bending due to external force, there is a problem that the surface light emitting device becomes heavy. In addition, when the gap between the light guide plate and the reflection plate is widened to an interval where the capillary phenomenon is unlikely to occur, the depth of the surface light emitting device increases, and the light irradiated backward from the light guide plate is forwarded by the reflection plate. There was a problem that light reflected to the light attenuates.
Moreover, even if the frame is sealed using a water-stopping material as in Patent Document 2, it is difficult to reliably maintain waterproofness due to aging of the water-stopping material, and water penetrates into the inside. There is also.
In that case, in the surface light-emitting device of Patent Document 2, the light source and the substrate on which the light source is mounted are not protected against drip, and if this portion touches water, a short circuit occurs and the light source and the mounting substrate are damaged. There was a possibility.

  In order to solve the above problems, the present invention does not increase the thickness of the light guide plate as a countermeasure for preventing capillary action even if there is water that has permeated from the outside or water that forms dew inside. The light guide plate and the reflection plate can be held at a constant interval without making the distance between the light plate and the reflection plate so wide, and the light source and the light source mounting board have a structure that does not allow water to enter even if water enters the inside. An object is to provide a surface light emitting device.

  In order to solve the above problems, the present invention provides a light source, a light source mounting substrate on which the light source is mounted, a light guide plate that irradiates light from the light source from a side incident surface to a front surface and a rear surface, and a rear surface from the light guide plate. A light source case using a heat conduction member and a light source of the light source mounting substrate that is at least partially in contact with the light source case on the incident surface of the light guide plate In a surface light emitting device including a light source unit disposed so as to face each other and a frame body that houses the light guide plate, the reflection plate, and the light source unit, a space between the light guide plate and the reflection plate is constant. Surface light emission characterized by having a constant distance between the light guide plate and the reflection plate regardless of the size of the surface light emitting device and the thickness of the light guide plate by inserting a member for holding the gap. Providing equipment.

  In the present invention, the synthetic resin is put in the light source case in a state where at least a part of the light source mounting substrate is in contact with the light source case, and at least the light source mounting substrate is filled until it is completely immersed. By doing so, it is possible to prevent damage to the light source and the light source mounting substrate due to a short circuit that occurs when water that has permeated from the outside or water generated by internal condensation adheres to the substrate. I will provide a.

  According to the present invention, the gap between the light guide plate and the reflection plate can be kept constant, and light unevenness due to water that has been infiltrated from the outside and water of dew condensation that has occurred inside the surface light emitting device can be maintained. Disappear. Further, according to the present invention, it is possible to prevent a short circuit due to the water that has permeated from the outside or the water of dew condensation that has occurred inside adheres to the light source or the light source mounting substrate.

1 is an overall view showing an example of a surface light emitting device according to the present invention. Expanded sectional view in FIG. Perspective cross-sectional view of the light source unit

Hereinafter, the surface light-emitting device according to the present invention will be described with reference to the drawings. However, the drawings are for explanation, and do not necessarily reflect actual shapes and dimensions.
FIG. 1 is a plan view of the entire surface light emitting device of this embodiment. 2 is an enlarged cross-sectional view taken along the line AA in FIG. 1. FIG. 3 is a cross-sectional view of a unit molded with the synthetic resin 4 by placing the light source 3a and the light source mounting board 3b in the light source case 5. Indicates. Further, the plan view of the entire surface light emitting device of FIG. 1 is a front view, and the upper portion of the device is the upper portion, the lower portion is the lower portion, the left is the left portion, and the right is the right portion.

  As shown in FIG. 2, the surface light emitting device 13 of the present embodiment uses a light source mounting substrate 3 b in which the light source 3 is mounted on the light incident surface 2 a of the light guide plate 2 to emit light from the light incident surface 2 a of the light guide plate 2 and the light source 3. It arrange | positions so that the surface 3c may oppose. Further, as shown in FIG. 3, at least a part of the light source mounting substrate 3b is completely immersed in the synthetic resin 4 in a state where the light source mounting substrate 3b is at least partially in contact with the light source case 5 using the heat conducting member. A light source unit 12 molded in a filled state is provided. Further, the light source unit 12 has a structure in which at least a part of the inner frame 1a serves as a guide so that the light source unit 12 can move in a direction perpendicular to the light incident surface 2a of the light guide plate 2 as shown in FIG. However, this structure is provided in the upper part, the lower part, the left part, the right part, the opposite part, or all.

The light source unit 12 is in a state where at least part of the light source unit 12 is in contact with the inner frame body 1a formed using the heat conducting member, and thereby heat generated by the light source 3a passes through the light source case 5 using the heat conducting member. It is possible to escape from the inner frame 1a to the outside.
As the light source 3a, a light emitting diode is used in this embodiment, but a light emitting diode other than a light emitting diode such as a cold cathode tube may be used.
The light source case 5 and the inner frame 1a are formed of a member having good thermal conductivity and excellent heat dissipation, and preferably formed of aluminum, for example.

In the present embodiment, the synthetic resin 4 is made of a material having a light transmittance of 80% or more, so that the light from the light source 3a is not attenuated, and the light source from the water that has been infiltrated from the outside or the dew condensation water that has been generated inside. 3a and the light source mounting substrate 3b can be protected. In this embodiment, the synthetic resin 4 is made of silicon, but, for example, urethane, rubber, or epoxy may be used.
In addition, when a portion other than the light emitting surface 3c of the light source 3a is filled with the synthetic resin 4, a material having a light transmittance of less than 80% may be used.

The light guide plate 2 is formed from a synthetic resin having a light transmittance of 80% or more such as an acrylic resin. In the light guide plate 2, a side surface on which the light source 3 a is disposed is a light incident surface 2 a, and a surface that is orthogonal to the light incident surface 2 a and reflects light incident from the light source 3 a is a reflective surface 2 b.
A surface that is orthogonal to the light incident surface 2a and is parallel to the reflecting surface 2b and that emits light reflected by the reflecting surface 2b is referred to as a light emitting surface 2c.
On the reflection surface 2 b of the light guide plate 2, a dot pattern for irradiating the reflection sheet 7 with light from the light source 3 a is formed. The dot pattern is, for example, a silk printing method for printing a dot pattern, a molding method for pouring a resin into a mold on which a dot pattern is formed, a V-groove cutting method for cutting grooves with a plotter, a laser method for scratching the surface with a laser wave, etc. Can be formed.

In front of the light emitting surface 2c of the light guide plate 2, a diffusion plate 10 that scatters and diffuses light emitted from the light emitting surface 2c is disposed, whereby the entire diffusion plate 10 can be made uniform in brightness.
In addition, a media sheet 11 such as a graphic printed on a transparent and translucent sheet is disposed on the front surface of the diffusion plate 10, or attached to the diffusion plate 10, or a part of the front surface of the diffusion plate 10 is light transmissive. The diffusion plate 10 can be used as the display plate surface by a method of directly printing with ink or a part of the ink that does not transmit light.
Moreover, it is good also as the surface emitting device 13 which does not use the diffusion plate 10 and the outer frame 1b.

  The reflection sheet 7 is disposed so as to face the reflection surface 2 b of the light guide plate 2 in order to reflect light irradiated from the reflection surface 2 b of the light guide plate 2. Thereby, the incident light can be efficiently reflected to the light emitting surface. The reflection sheet 7 may be provided with a reinforcing plate 6 in order to reinforce the reflection sheet 7. Moreover, you may use what applied the coating material with a light reflectivity of 85% or more to the reinforcement board 6 instead of the reflective sheet 7. FIG.

By attaching the reflection sheet 7 to the reinforcing plate 6 as a reflection plate 14 and inserting a spacer 8 between the reflection plate 14 and the light guide plate 2, the distance between the light guide plate 2 and the reflection plate 14 can be kept constant. I can do it. As a result, for example, when the condensation is on the entire light guide plate and the central portion of the light guide plate 2 is bent by an external force such as wind pressure, the light unevenness caused by the water gathering and gathering at the central portion due to capillary action is reduced. Can be prevented.
The gap 15 between the reflecting plate 14 and the light guide plate 2 is preferably 3 mm or more in terms of preventing capillary phenomenon and preventing unnecessary thickness of the surface light emitting device 13 itself. Further, depending on the material and surface state of the light guide plate 2 and the reflection sheet 7, there is a case where the capillary phenomenon is unlikely to occur, and therefore a gap of 1.0 mm or more may be used.
In the definition that the capillary phenomenon is unlikely to occur, the standard is ambiguous. Therefore, in the present invention, the definition is as follows. Regardless of the spacing of the gap 15, the capillary phenomenon is unlikely to occur if it is within 5 mm from the water surface.

In the present invention, the spacer 8 is inserted between the light guide plate 2 and the reflection plate 14 to make the gap 15 constant. Although there is a conventional technique in which the above structure is used in a backlight device of a liquid crystal display panel, the present invention has fundamentally different problems and solutions from the backlight of a liquid crystal display panel.
The difference between the present invention and the backlight of the liquid crystal display panel is that the gap 15 between the light guide plate 2 and the reflection plate 14 is separated by 1.5 mm or more by the spacer 8 for the purpose of the present invention to prevent light unevenness due to capillary action. On the other hand, the backlight of a liquid crystal display panel uses an extremely small spacer of 0.1 mm or less as a countermeasure against luminance unevenness due to scratches on the light guide plate and the reflector and to prevent distortion of the prism lens. Is completely useless to prevent capillary action. From this, it is apparent that the present invention has a different purpose from the conventional technology of the backlight of the liquid crystal display panel.

The spacer 8 used in the present invention is preferably a member having a low light transmittance because a member having a high light transmittance is the same as the state in which water has entered and causes light unevenness. In addition, the definition with low light transmittance shall be 10% or less of light transmittance. As the member, a synthetic resin other than metal may be colored with a color having low light transmittance. Moreover, it is preferable that the color saturation belongs to a white system about the surface of the said member and the colored color.
The shape of the spacer 8 is preferably a hemispherical shape or a semi-flat spherical shape, but a shape such as a cone or a polygonal pyramid may be used. Specifically, the ratio of the longest distance to the radius or the center of gravity of the polygon with respect to the height of the spacer 8 is preferably 1 or more.
In addition, the arrangement density of the spacers 8 is one in a radius of 500 mm in this embodiment, but it is preferably 100 mm or more in view of preventing the cost from being increased due to unnecessary arrangement. .
In the present embodiment, the spacer 8 is fixed by making a hole in the reflector 14 and attaching the spacer 8 having the above-mentioned shape to the hole. For example, an adhesive, double-sided tape or reflector 14 is used. You may hit it like a nail. Further, after the spacer 8 is attached to the reinforcing plate 6 by the above-described fixing method, a reflective sheet may be attached, or a paint having a light reflectance of 80% or more may be applied instead of the reflective sheet 7.

1a. Inner frame 1b. Outer frame 1c. Affixing surface 2. Light guide plate 2a. Light incident surface 2b. Reflective surface 2c. Light emitting surface 3a. Light source 3b. Light source mounting substrate 3c. 3. Light emitting surface 4. Synthetic resin Light source case 5a. Affixing surface 6. Reinforcing plate 7. Reflective sheet 8. Spacer 9. Elastic working member 10. Diffusion plate 11. Media sheet 12. Light source unit 13. Surface light-emitting device 14. Reflector 15. Gap

Claims (6)

  A light source, a light source mounting substrate on which the light source is mounted, a light guide plate that irradiates light of the light source from a side incident surface to a front surface and a rear surface, and light that is irradiated from the light guide plate to the rear surface is reflected in the front direction. A light source unit including a reflector, a light source case using a heat conducting member, and a light source of the light source mounting substrate that is at least partially in contact with the light source case so as to face an incident surface of the light guide plate And a surface light emitting device including the light guide plate, the reflection plate, and a frame housing the light source unit, and a member for holding a space between the light guide plate and the reflection plate is inserted. A surface light emitting device characterized by the above.   The surface light emitting device according to claim 1, wherein the surface of the member for holding the light guide plate and the reflection plate at a constant interval is white or milky white.   The member for holding a space between the light guide plate and the reflection plate at a constant interval uses a hemispherical or polygonal pyramid member. The surface light-emitting device described in 1.   In a state where at least a part of the light source mounting substrate is in contact with the light source case, a synthetic resin is placed in the light source case, and is molded in a state where at least the light source mounting substrate is fully immersed. The surface light-emitting device according to claim 1, wherein the surface light-emitting device is characterized by the following.   The said frame is formed using the heat conductive member, At least one part of the said light source case is in contact with the said frame, The claim in any one of Claims 1-4 characterized by the above-mentioned. Surface light emitting device.   The uniform light emission can be achieved by forming a scatterer that reflects and scatters light emitted from the light source on the surface of the light guide plate by a predetermined processing method. The surface emitting device according to claim 5.

Images