JP2011049144A - Led illumination system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a LED illumination system having a high illuminance and using a light guide member, capable of obtaining uniform distribution of illuminance over the entirety. <P>SOLUTION: The LED illumination system 10 includes a light guide member 11 for guiding the light entered from an end surface to the other end surface by making all the light reflect to a side surface thereof; a LED light source for emitting the light to enter the one end surface of the light guide member; and diffusion reflecting materials for reflecting to defuse the light which enters from the LED light source into the light guide member to a side surface opposite to at least a light outgoing surface 11C of the light guide member; the light-outgoing surface is formed in at least a side surface of the light guide member, in a direction of outgoing from the light-outgoing surface; and while a diffusion-reflecting surface for transmitting the light from the one side surface is formed, arranged opposite to each other via an air layer outside of the side surface formed with at least the diffusion reflecting surface of the light guide member. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  Many lighting devices have used fluorescent lamps or the like as light sources, but those using LEDs as light sources have been put into practical use in various fields in recent years. Since an LED has higher luminous efficiency than a fluorescent lamp, an illumination device using the LED as a light source can reduce power consumption.

  In the case of forming a linear or planar illumination device using an LED as a light source, a method in which a large number of LED elements are juxtaposed at equal intervals in a linear or planar manner is common.

  However, in this method, since a large number of light sources are arranged in the form of dots, it is difficult to obtain a linear or planar light source with uniform brightness as a whole. Therefore, a sheet-like diffusing member having a diffusing effect is arranged on the front surface of the LED element, and the straight light from the LED element is diffused to obtain a linear or planar light source having a uniform and smooth brightness distribution. It has been broken. However, since the light transmittance of the diffusing member is as low as about 60%, the light use efficiency is reduced, and the illuminance is low and dark, so that the illumination device using the LED as the light source is replaced with the illumination device using the fluorescent lamp. I couldn't replace it.

  In order to solve these problems, a linear or planar illumination device using a light guide technique as shown in Patent Document 1 has been proposed.

  The structure of the conventional 1st illuminating device shown by patent document 1 is shown in FIGS.

  8-10, 50 is an illuminating device, LED element 51, the board | substrate 52 holding this, LED case 53 which accommodates these, and the LED element which injected from the light-incidence surface 54a, 54b of upper and lower ends And a flat light guide member 54 that emits light from the front light exit surface 54e. The light guide member 54 is made of a transparent acrylic plate or glass plate, and the incident LED element 51 is placed on the back surface 54f facing the front light exit surface 54e along the traveling direction of the light incident from the light incident surfaces 54a and 54b. Diffusing means is formed of a V-groove 57 or the like that changes the traveling direction so that the light is diffusely reflected and emitted from the light exit surface 54e. A reflective sheet 56 is in close contact with the back surface 54f where the V-groove 57 is formed. The V-groove 57 of the diffusing means is such that the groove closer to the LED element 51 has a shallower groove depth or a coarser groove density so that the amount of diffused light toward the light exit surface 54e becomes smaller. Further, the groove located farther from the LED element 51 has a deeper groove depth or a higher groove density to increase the amount of diffused light toward the light exit surface 54e. As a result, the overall brightness distribution of the light exit surface 54e can be made uniform.

  As the reflection sheet 56, a white plastic sheet having a high reflectance is used. It is desirable that the reflection sheet 56 and the light guide member 54 be in close contact as much as possible, and a reflecting mirror may be used instead of the reflection sheet. Further, when a highly reflective paint is applied to the outer surface of the light guide member 54, a reflection sheet is not necessary.

  The illuminating device 50 includes the light guide member 54 and the substrate 52 disposed so that the light emission surfaces of the LED elements 51 are positioned on the upper and lower light incident surfaces 54 a of the light guide member 54. The LED case 53 is covered so as to cover the part.

  In such an illuminating device 50, when power is supplied from a power source and the LED element 51 is turned on, light emitted from the LED element 51 is transmitted from the light incident surfaces 54a and 54b as shown by arrows in FIG. And proceeds while totally reflecting through the light guide member 54. Since the V-groove 57 is changed in depth and density according to the distance from the LED element, the traveling light is changed in the traveling direction by the inclined surface 57a and becomes irregularly reflected light, and is almost uniform from the entire surface of the light emitting surface 54e. Similarly, since the intensity is emitted as indicated by the arrow, the illuminance unevenness on the entire surface of the light exit surface 54e is reduced, and an almost uniform illuminance distribution can be obtained.

JP 2005-142032 A

  In the above-described conventional device, the illuminance on the light-emitting surface is made uniform by adjusting the depth and pitch of the groove forming the light diffusion surface of the light guide member according to the distance from the LED element. Since the reflection sheet is adhered to the back surface of the light diffusing surface of the member or a highly reflective paint is applied, total reflection occurs on the light diffusing surface, and the light diffusing effect is impaired. For this reason, there is a problem in that the amount of light emitted from the light exit surface of the light guide member is reduced, and sufficient illuminance cannot be obtained, resulting in overall darkness.

  The subject of this invention is providing the LED illuminating device using the light guide member which can solve such a problem and can obtain uniform illumination intensity distribution with high illuminance on the whole.

  In order to solve the above-mentioned problems, the present invention is directed to a light guide member that totally reflects light incident from one end surface on the side surface and guides the light to the other end surface side, and emits light to one end surface of the light guide member. An LED light source including an LED element to be used and at least one side surface of the light guide member as a light exit surface, and light incident on the light guide member from the LED light source on at least a side surface of the light guide member facing the light exit surface A diffuse reflection surface is formed so as to diffusely reflect in the direction of exiting from the light exit surface and to be transmitted from the one side surface, and air is provided outside at least the side surface of the light guide member where the diffuse reflection surface is formed. The diffusive reflecting member is disposed so as to face each other through the layers.

  Further, in the present invention, the light guide member is composed of a long member whose side surface is longer than the width of the end surface, and the diffusion reflection surface formed on the side surface has a light diffusion angle as the distance from the end surface is smaller. It is preferable to set such that the light diffusion angle is set to be smaller and the light diffusion angle is larger as the value is larger.

  The diffuse reflection surface can be formed with spherical minute irregularities that form microlenses. The diffusion surface is preferably formed such that the diffusion angle changes stepwise depending on the position in the surface.

  According to this invention, at least the back surface of one side surface on which the diffuse reflection surface of the light guide member is formed is disposed so as to face the reflection member via the air layer, and thus the diffuse reflection surface formed on one side surface of the light guide member. The light that is transmitted through this surface without being diffused by the light is reflected by the reflecting member, is incident on the light guide member again, and is emitted from the light exit surface, so that the diffusion effect is increased and the lighting device is bright. be able to.

  Even if it is a long illuminating device using a long light guide member, the amount of light diffused on the diffusion surface formed on one side surface of the light guide member is changed to a light incident surface on which LED light emitted from the light guide member is incident. Therefore, the brightness of the light emitted from the light exit surface of the light guide member becomes uniform as a whole.

The perspective view which shows the external appearance of the illuminating device by the Example of this invention. The disassembled perspective view which shows the structure of the illuminating device by the Example of this invention. The disassembled perspective view which shows the structure of the LED light source of the illuminating device by the Example of this invention. Sectional drawing which expands and shows a part of illuminating device by the Example of this invention. The perspective view of the light guide member used for operation | movement description of this invention. Operation | movement explanatory drawing of this invention. The characteristic line figure which shows the illumination intensity distribution characteristic of the illuminating device of this invention. The front view which shows the structure of the conventional illuminating device. The disassembled perspective view which shows the structure of the conventional illuminating device. Sectional drawing which expands and shows the cross section which follows the AA line of FIG.

  Embodiments of the present invention will be described with reference to the embodiments shown in the drawings.

  1 to 5 show an embodiment of the present invention. In these drawings, reference numeral 10 denotes a main body of a lighting device. As shown in FIG. 2, the main body 10 includes a long flat light guide member 11 formed of a transparent acrylic resin, and a groove-shaped metal holding frame 13 that holds the light guide member 11. The reflector 12 is interposed between the light guide member 11 and the holding frame 13. The light guide member 11 accommodated in the holding frame 13 is fixed so as not to fall off the holding frame 13 by a press plate 14 screwed to the holding frame 13 with a set screw 15.

  An LED light source 20 is coupled to both ends of the illumination device body 10. As illustrated in FIG. 3, the LED light source 20 includes a plurality of LED elements 21 supported by a substrate 22 and an LED cover 23 that accommodates the LED elements 21. The LED cover 23 is made of an insulating resin, and accommodates therein a heat conducting plate 25 that is thermally coupled to the LED elements 21 via a heat dissipation sheet 24 as shown in FIG. The lead wire 28 drawn out from the substrate 22 is drawn out from a lead lead-out port 29 provided on the side surface of the cover 23 and connected to a power source.

  The heat conducting plate 25 accommodated in the LED cover 23 is fixed to the top wall of the LED cover 23 by screwing or the like, and a board 22 that supports the LED element 21 is attached to a mounting seat 23 a provided in the LED cover 23. 27. Thus, the LED elements 21 housed in the LED cover 23 come into contact with the heat conducting plate 25 through the heat radiating sheet 24, and the heat generated by the LED elements 21 is conducted to the heat conducting plate 25 through the heat radiating sheet 24. .

  In the LED light source 20 configured in this way, the LED element 23 in the LED cover 23 is inserted into the both ends of the holding frame 13 of the illuminating device body 10 so that the LED element 21 in the LED cover 23 of the light guide member 11 in the holding frame 13 is fitted. It arrange | positions facing both end surfaces. Thereby, the light emitted from the LED element 21 can be incident into the light guide member 21 from the end surfaces 11 a and 11 b which are light incident surfaces of the light guide member 11. Further, the inner surface of the heat conducting plate 25 in the LED cover 23 comes into contact with the outer surface of the holding frame 13 of the main body 10 as shown in FIG. Thereby, the heat of the LED element 21 conducted to the heat conducting plate 25 through the heat radiating sheet 24 is conducted to the metal holding frame 13, and is radiated from the surface of the holding frame 13 to the atmosphere. Can be cooled.

  As shown in FIG. 5, the light guide member 11 is configured by an elongated rectangular parallelepiped formed of a transparent acrylic resin having a side length longer than the end face width. The LED light source 20 is disposed so as to face both end faces 11a and 11b serving as light incident surfaces. In the light emitted from the LED light source that has entered the light guide member 11 from the light incident surfaces 11a and 11b, one of the four side surfaces of the light guide member 11 serves as the light exit surface 11c. In order to change the traveling direction so that the light incident on the light guide member 11 is emitted from the light exit surface 11c, this surface diffuses at least in the side surface 11d facing the light exit surface 11c in the side surface. A large number of minute spherical irregularities 11v such as a microlens are randomly formed so as to be a reflective surface by texture processing or the like.

  The diffuse reflection surface 11d formed by a large number of minute irregularities 11v is divided into an end portion 11d-1 close to the LED light source 20 and a central portion 11d-2 far from the LED light source 20, and the end portion 11d-1 The light diffusion angle on the surface is set to a small angle of about 6 °, for example, and the light diffusion angle on the reflection surface is set to a large angle of about 12 ° in the central portion 11d-2, so that The light reflection function (the amount of reflected light) is increased at a portion farther from the portion closer to the light source. This compensates for the attenuation of light propagating through the light guide member. Adjustment of the reflection function in the diffuse reflection surface 11d can also be performed by changing the size and height of the unevenness forming the diffuse reflection surface 11d. In this case, the diffuse reflection surface 11d can be formed so that the reflection function gradually changes according to the distance from the light source, or can be formed so as to change stepwise. It is advantageous in terms of manufacturing cost to use a changing diffuse reflection surface.

  As a method of processing the diffuse reflection surface, there is a method of pressing using a mold. In other words, the light guide member 11 is formed with a diffuse reflection surface having minute irregularities by pressing a mold on which the shape of the original plate having minute irregularities is transferred by electroforming. be able to.

  Next, the propagation operation of the light incident from the LED light source 20 in the light guide member 11 will be described.

  As shown in FIG. 6, the light emitted from the LED light source 20 is incident on the light guide member 11 from the light incident surfaces 11 a and 11 b on the end surface of the light guide member 11 through the air layer in the space. The light incident on the light guide member 11 is totally reflected by the difference in refractive index between the light guide member 11 and air at the interface in contact with the air in the space on each side surface of the light guide member 11. To the other end face.

  In order to cause total reflection of light, it is necessary to apply light to the interface of the light guide member at an angle greater than the critical angle caused by the difference in refractive index between the light guide member and air. Since the light incident angle is within a certain angle due to the difference in refractive index at the time when the light enters 11, when the light strikes the interface with the air on the side surface of the light guide member 11, an angle greater than the critical angle is maintained. Yes. In order to maintain this relationship and allow light to travel in the light guide member, it is desirable that the surface of the side surface of the light guide member be a smooth surface without unevenness.

  In order to emit light from the light guide member 11 to the outside, that is, in the atmosphere, the light is transmitted by the diffuse reflection surface 11d formed on one of the side surfaces of the light guide member 11 and the diffuse reflection sheet 12 disposed outside the diffuse reflection surface 11d. It is necessary to intentionally change the angle of reflection to break the total reflection condition so that total reflection does not occur.

As shown in FIG. 6, the light that has been propagated by being totally reflected in the light guide member 11 is diffused by being diffused by hitting the side surface on which the diffuse reflection surface 11 d is formed, the reflection angle is changed, and the side surface that becomes the light exit surface It hits 11c at an angle less than the critical angle, passes through the interface, and emits light into the atmosphere. On the other hand, on the diffuse reflection surface 11d, since the total reflection conditions are also changed due to the unevenness, a part of the light hitting this surface is transmitted through this surface and directed to the outer diffuse reflection sheet 12, where it is reflected. Then, the light passes through the diffuse reflection surface 11d, returns to the light guide member 11 again, is guided through the light guide member 11, and is emitted from the light exit surface.
Thereby, the light guide efficiency by the light guide member 11 increases, the emitted light quantity from the light emission surface 11c increases, and it can be set as a bright illuminating device with high illumination intensity.

  By providing the diffuse reflection surface 11d of the light guide member 11 with two or more regions where the light diffusion angle changes according to the distance from the light source, the amount of light emitted from the light exit surface 11c is adjusted as shown in FIG. Thus, the entire illuminance can be made uniform. The horizontal axis of FIG. 7 indicates the length (distance) of the optical member 11, with the center as the reference position, the distance from this position to the left is a negative number, and the distance to the right is a positive number. The vertical axis represents illuminance.

  When elongating the illumination range of the illuminating device using the light guide member, the light diffusion angle of the diffuse reflection surface 11d of the light guide member 11 is divided into several stages according to the distance from the light source. By finely adjusting, it is possible to make uniform the illuminance distribution by adjusting the total amount of light emitted from the light guide member.

  Further, since the reflection sheet 12 reflects the light transmitted and scattered by the diffuse reflection surface 11d and returns it to the light guide member 11, it can be propagated further through the light guide member 11, and the overall illuminance can be increased. Can be increased.

  In this embodiment, the diffusion angle is changed in two stages, but the light diffusion angle may be changed in more stages.

  In addition, as a method of fixing the reflection sheet 12 to the outside of the diffuse reflection surface 11d through an air layer, a method of bonding the reflection sheet 12 to the outside of the diffusion reflection surface 11d with an adhesive tape can be used. The adhesive tape is attached to a part of the diffuse reflection surface 11d. In this way, the diffuse reflection surface 11d and the adhesive tape, and the reflection sheet 12 and the adhesive tape are closely bonded to each other by the adhesive function of the adhesive tape, so that the diffusion reflection surface 11d and the reflection sheet 12 are equal to the thickness of the adhesive tape. And an air layer can be formed between them.

  Further, in the portion where the diffuse reflection surface 11d, the adhesive tape, and the reflective sheet 12 are in close contact, a light diffusing function by the adhesive tape is added. For example, when the material of the adhesive tape is a nonwoven fabric, since the nonwoven fabric has minute irregularities, the light transmitted through the diffuse reflection surface 11d is diffused by the adhesive tape.

  Since the diffusion characteristic by the adhesive tape is different from the diffusion characteristic by the diffusive reflection surface, the diffusion characteristic changes between the part where the adhesive tape is attached to the diffuse reflection surface 11d and the part where the adhesive tape is not attached. By utilizing this fact, by appropriately selecting the position where the adhesive tape is applied and the area of the adhesive tape, combined with the diffusion characteristics of the diffuse reflection surface 11d and the reflection sheet 12, the illuminance can be made uniform or the illuminance can be reduced. Improvements can be made.

  For example, when the diffuse reflection surface is formed of minute spherical irregularities such as microlenses, the diffuse reflection surface and a part of the reflection sheet 12 are fixed with an adhesive tape, and the equipment constituting the adhesive tape is a nonwoven fabric In the portion where the adhesive tape is affixed, the diffusion angle is larger than the diffusion angle of the diffusive reflection surface, so that the attenuation of light propagating through the light guide member 11 is smaller than that in the portion where the adhesive tape is not affixed. growing. In other words, since there is a portion where the adhesive tape is affixed, more light can be diffused and released into the atmosphere.

  The diffusion function by the pressure-sensitive adhesive tape is exhibited even if the diffuse reflection surface to which the pressure-sensitive adhesive tape is attached is a smooth surface without minute irregularities. That is, the difference between the refractive index of the light guide member and that of the air layer is smaller at the part where the adhesive tape of the smooth surface where the microscopic irregularities of the diffused reflection surface of the light guide member are not adhered. Since it is optically integrated with the light guide member, a part of the incident light is transmitted through the smooth surface without being totally reflected, and is diffused by the minute unevenness of the base material of the adhesive tape.

  As described above, if the adhesive tape is applied to the smooth surface of the light guide member 11 to exhibit the diffusion function, the adhesive tape is formed without forming minute irregularities on the portion of the light guide member where light is to be diffused. The diffusion function can be easily realized by pasting.

10: LED illumination device 11: light guide members 11a, 11b: light incident surface 11c: light output surface 11d: diffuse reflection surface 12: diffuse reflection sheet 20: LED light source

Claims (4)

  A light guide member that totally reflects light incident from one end surface on the side surface and guides the light to the other end surface side; an LED light source including an LED element that emits emitted light to one end surface of the light guide member; At least one side surface of the light member is used as a light exit surface, and light incident on the light guide member from the LED light source is diffusely reflected in a direction emitted from the light exit surface on at least the side surface facing the light exit surface of the light guide member. In addition, a diffuse reflection surface formed so as to be transmitted from the one side surface is formed, and the diffuse reflection member is disposed so as to face the outside of at least the side surface of the light guide member where the diffuse reflection surface is formed via an air layer. LED lighting device characterized by this.   2. The LED lighting device according to claim 1, wherein the light guide member is formed of a long member whose side surface is longer than the width of the end surface, and the diffuse reflection surface formed on the side surface has a smaller distance from the end surface. An LED lighting device, wherein the light diffusion angle is set to be small and the light diffusion angle is set to be larger as the light diffusion angle is larger.   3. The LED lighting device according to claim 1, wherein the diffuse reflection surface is formed of spherical minute unevenness that forms a microlens.   4. The LED illumination device according to claim 1, wherein the diffusion reflection surface is formed so that a diffusion angle changes stepwise depending on a position in the surface. 5. apparatus.

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