JP5227944B2 - Lighting device - Google Patents

Description

  The present invention relates to a lighting device using a light emitting diode (LED) as a light source.

  2. Description of the Related Art Conventionally, illumination devices that emit light in a planar shape or linear shape using LEDs as light sources have been proposed. For example, in Patent Document 1, LEDs that are a plurality of point light sources are arranged in a planar shape or a linear shape, a reflecting plate is arranged around each LED, and a translucent plate is arranged on the light emission direction side of the LED. A light box is disclosed.

  Patent Document 1 mentions the material of the reflecting plate and the plate having translucency, but does not mention the linear expansion coefficient of these materials. Further, there is no mention of the material of the mounting board on which the LED serving as the light source is mounted, the material of the fixing member that fixes the mounting board, and the linear expansion coefficient. Generally, a metal material is used as a material for a mounting substrate on which an LED is mounted or a fixing member for fixing the mounting substrate in order to efficiently dissipate heat generated by the LED. This metal material has a combination of materials in which the difference in linear expansion coefficient is 20 times as large as the difference in linear expansion coefficient is larger than that of a plastic material used for a reflecting plate or a light-transmitting plate.

JP 2008-270144 A

  Due to the difference in coefficient of linear expansion, the thermal expansion of the reflector using the plastic material is larger than that of the fixing member using the metal material due to the heat generated when the LED is turned on, and the reflector is distorted. This distortion of the reflecting plate may cause a decrease in the total light amount of the lighting device and a change in the light distribution shape.

  As a method of relieving the distortion, there is a method of dividing the reflector in the direction perpendicular to the direction in which the thermal expansion greatly acts. In the case of a configuration in which the reflector is divided in the vertical direction, it is necessary to provide a gap for absorbing thermal expansion between the reflectors.

  Although it is possible to reduce the distortion of the reflecting plate due to thermal expansion by providing this gap, a part of the light emitted from the LED is reflected by the surface of the light-transmitting plate, and the gap between the reflecting plates Enter as stray light. This light is repeatedly reflected and attenuated in the gap, and is no longer emitted from the surface of the translucent plate. For this reason, when viewed from the surface side of the translucent plate, there is a problem that a linear shadow is generated in the gap.

  The present invention has been made in view of the above-described problems, and it is possible to reduce the shadow that occurs between the reflecting plate and the reflecting plate while reducing the distortion of the reflecting plate caused by the difference in linear expansion coefficient. It aims at providing the illuminating device which uses LED which can be made as a light source.

In order to achieve the above object, the present invention provides the following lighting device.
(1) A plurality of light source modules adjacent to each other, each including a plurality of LEDs as light sources, a mounting board on which the LEDs are mounted, and a reflecting plate that is disposed so as to surround the LEDs and has a shape that extends in the light emission direction of the LEDs. And a light-transmitting plate that covers the reflecting plates of the plurality of light source modules, and of the two adjacent light source modules, the reflecting plate of one of the light source modules is disposed on the outer periphery thereof. An illuminating device having a flat portion, wherein the reflector of the other light source module has a step portion on an outer peripheral portion thereof, and the flat portion and the step portion overlap each other.
(2) The length of the reflecting plate in the adjacent direction of the light source module is L, the length of the flat portion and the stepped portion in the adjacent direction is ΔL, the linear expansion coefficient of the material of the reflecting plate is α, and the temperature during use When the rising value is ΔT, the length ΔL of the flat portion and the step portion is ΔL> L × α × ΔT
The lighting device according to (1), wherein the relational expression is satisfied.

  ADVANTAGE OF THE INVENTION According to this invention, the shadow which arises between a reflecting plate and a reflecting plate can be made thin, relieving the distortion of a reflecting plate which arises by the linear expansion coefficient difference in the illuminating device which uses LED as a light source.

It is a perspective view which shows an example of the illuminating device which does not have the structure of this invention. It is A-A 'sectional drawing of FIG. It is a perspective view which shows one Example of the illuminating device which concerns on this invention. FIG. 4 is a B-B ′ sectional view of FIG. 3. FIG. 5 is a partially enlarged view of FIG. 4. It is a whole perspective view which shows an example of the illuminating device which concerns on this invention.

  Hereinafter, examples of the lighting device according to the present invention will be described. Before that, a lighting device not having the configuration of the present invention will be described first. The reference numerals described in the drawings are all common numerals in the drawings described below. Reference numeral 1 denotes a lighting device, 2 denotes an LED, 3 denotes a mounting substrate, 4 denotes a fixing member, 5 denotes a light-transmitting plate, 6 denotes a reflecting plate, 61 denotes a flat portion provided on the outer periphery of the reflecting plate, and 62 denotes A stepped portion provided on the outer periphery of the reflector, 7 is a light source module, and 8 is a gap formed between the reflectors.

FIG. 1 is a perspective view illustrating an example of a lighting device that does not have the configuration of the present invention, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. As illustrated, the lighting device 1 includes a plurality of LEDs 2 as light sources. The LED 2 is electrically connected to the mounting substrate 3 and mounted. The mounting substrate 3 also has a function for efficiently propagating the heat generated from the LEDs 2 and dissipating heat. Further, the mounting substrate 3 is fixed to the fixing member 4 in order to release the heat generated from the LEDs 2 to the outside of the lighting device 1. At this time, for the purpose of reducing the air layer between the mounting substrate 3 and the fixing member 4, a heat radiation grease, a heat radiation sheet, or a heat radiation tape may be interposed therebetween.
The light emitting direction of the LED 2 is light-transmitting for the purpose of preventing humans from directly touching the charging part, lens part, and resin sealing part of the LED, and preventing entry of dust and insects. A plate 5 is disposed.
Most of the light emitted from the LED 2 is transmitted through the light-transmitting plate 5 and emitted from the lighting device 1, but the light reflected or refracted on the surface or inside of the light-transmitting plate 5 is reflected. A part returns to the mounting substrate 3 side. A reflecting plate 6 is disposed so as to surround the LED 2 for the purpose of further reflecting the returned light and transmitting the light through the translucent plate 5 to reuse the light.

  Examples of the material of the fixing member 4 include highly heat conductive resins, metals, and ceramics. Among these, a steel plate and an aluminum plate are preferable because of their excellent mechanical strength, heat dissipation, heat resistance, and workability. .

  As the material of the light-transmitting plate 5, glass, acrylic, polycarbonate, polystyrene, polypropylene, cyclic polyolefin, or the like having high light transmittance is preferable.

  In order to give diffusibility, the light-transmitting plate 5 has a prism-shaped molding on one or both sides, a lens-shaped molding, a mat processing, or a plate. It is preferable to use a mixture of fine particles that enhance diffusibility.

  The material of the reflecting plate 6 is an insulating material because it is disposed on the surface of the mounting substrate 3 on which an electrical wiring pattern is applied, and a plastic material is preferable because it has good moldability.

  In order to increase the reflectance of the reflecting plate 6, it is preferable to make the material of the reflecting plate 6 itself a highly reflective material, or to coat or deposit a highly reflective material on the surface.

When a plurality of LEDs 2, a mounting substrate 3, and a reflecting plate 6 are provided as a single module 7, and the lighting device 1 in which a plurality of modules 7 are arranged is provided, a fixing member 4 for fixing the mounting substrate 3 is, for example, a steel plate (Linear expansion coefficient α: about 10 × 10 ⁻⁶ / ° C.) or aluminum plate (α: about 24 × 10 ⁻⁶ / ° C.) is used. On the other hand, since a plastic material (α: about 50 to 200 × 10 ⁻⁶ / ° C.) is used for the reflecting plate 6, a difference of 2 to 20 times occurs in the linear expansion coefficient between the fixing member 4 and the reflecting plate 6. When the reflection plate 6 has a large thermal expansion and the module 7 is designed in consideration of the thermal expansion, it is necessary to provide a gap 8 between the modules. A part of the light 9 reflected from the surface of the translucent plate 5 enters the gap 8 as stray light, and most of the light 9 is effectively reflected and attenuated in the gap 8. Is no longer used. For this reason, when the illuminating device 1 is seen from the surface side of the board 5 which has translucency, the part located in the clearance gap part 8 will become a linear shadow.

  FIG. 3 is a perspective view showing an embodiment of a lighting device according to the present invention, and FIG. 4 is a cross-sectional view taken along the line B-B ′ of FIG. 3. As shown in the figure, the illumination device 1 of the present embodiment includes a plurality of LEDs 2 as light sources, a mounting substrate 3 on which the LEDs 2 are mounted, and a reflector 6 that is disposed so as to surround the LEDs 2 and has a shape that extends in the light emission direction of the LEDs. A plurality of light source modules 7 adjacent to each other and a light-transmitting plate 5 that covers the reflection plates 6 of the plurality of light source modules 7, and one of the two light source modules 7 adjacent to each other. The reflecting plate 6 has a flat portion 61 on its outer peripheral portion, and the reflecting plate 6 of the other light source module 7 has a step portion 62 on its outer peripheral portion, so that the flat portion 61 and the step portion 62 overlap each other. The By overlapping the flat portion 61 and the stepped portion 62, distortion due to thermal expansion of the reflecting plate 6 can be alleviated, and stray light entering the gap portion 8 can be reduced or eliminated, and a shadow that can be formed in the gap portion 8 between the light source modules. Can be made thinner. The step size of the step portion 62 is preferably equal to or greater than the thickness of the flat portion 61.

FIG. 5 is a partially enlarged view of FIG. As shown in the figure, the length of the reflecting plate 6 in the adjacent direction of the light source module is L, the length of the flat portion 61 and the stepped portion 62 in the adjacent direction is ΔL, and the linear expansion coefficient of the material of the reflecting plate 6 is α. When the temperature rise value at that time is ΔT, the length ΔL of the flat portion 61 and the stepped portion 62 is ΔL> L × α × ΔT
It is preferable that the relational expression is satisfied. Further, when the machining tolerance of each part is a value that cannot be ignored, it is more preferable that the dimension design has a margin for the machining tolerance.

  FIG. 6 is an overall perspective view showing an example of a lighting device according to the present invention. In this example, two modules 7 are arranged in series on both sides of the square illumination device 1, but the shape of the illumination device 1 and the arrangement of the plurality of modules 7 are not limited to this.

1 Lighting device 2 LED
3 mounting substrate 4 fixing member 5 translucent plate 6 reflecting plate 61 flat portion 62 step portion 7 light source module 8 gap portion

Claims (2)

  A plurality of LEDs as light sources, a mounting board on which the LEDs are mounted, and a plurality of light source modules adjacent to each other, each having a reflector disposed so as to surround the LEDs and extending in the light emission direction of the LEDs; A light-transmitting plate that covers the reflecting plates of the plurality of light source modules, and of the two adjacent light source modules, the reflecting plate of one of the light source modules has a flat portion on the outer periphery thereof. And the reflector of the other light source module has a stepped portion on the outer periphery thereof, and the flat portion and the stepped portion overlap each other. The length of the reflection plate in the adjacent direction of the light source module is L, the length of the flat portion and the step portion in the adjacent direction is ΔL, the linear expansion coefficient of the material of the reflection plate is α, and the temperature rise value during use is When ΔT, the length ΔL of the flat part and the step part is ΔL> L × α × ΔT
The lighting device according to claim 1, wherein the relational expression is satisfied.

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