JPH0429579Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention can be used as an indicator light for displaying a display either singly or in combination, or when it is implemented in a non-luminous display device such as a liquid crystal display device and used as a light source. The present invention relates to an LED light emitting device used for various purposes.

[Conventional technology]

An LED light emitting device used as an indicator light or as a light source for a non-light emitting display device such as a liquid crystal display device has, for example, a plurality of light emitting diode chips (hereinafter referred to as LED chips) on an electrode on its surface.
a substrate to which is bonded; a reflective frame formed on the peripheral edge of the substrate; a light guide layer made of a transparent or translucent molding material filled in the reflective frame; It is roughly composed of a diffusion sheet that is laid and fixed.
When mounting an LED light emitting device on a device such as a liquid crystal display, there is no particular problem if a certain amount of mounting area is secured, but in reality, LED light emitting devices are The mounting area is also becoming smaller, and along with this, LED
It is desired that the light emitting device itself be made thinner.

[Problem that the invention attempts to solve]

By the way, the thickness of the LED light emitting device mentioned above is
If you make it thinner based on the directional characteristics of the LED,
Provides directivity with the strongest emission intensity in the vertical direction
Not only LEDs, but also omnidirectional LEDs where there is not much difference in luminous intensity depending on the angle.
Dispersion in the intensity distribution of the light emitted from the LED was noticeable, and the uniformity of brightness was lacking. Therefore, even if this type of LED light emitting device is mounted on a liquid crystal display device or the like, since the LED light emitting device does not emit surface light, uniform light cannot be obtained, and the device cannot be used as a light source or indicator light.

Therefore, the present invention was developed in view of the above points, and it is possible to reduce the mounting area by making the entire device thinner, and also to make the intensity distribution of the light emitted from the LED chip uniform, so that it can maintain a constant brightness state. Ideal for surface-emitting indicator lights or light sources.
The purpose is to provide LED light emitting devices.

[Means for solving problems]

LED related to this invention to achieve the above purpose
A light emitting device consists of a substrate on which a plurality of light emitting diode chips are bonded onto electrodes on the surface thereof, a reflective frame formed on the periphery of the substrate, and a transparent or semi-transparent material filled inside the reflective frame. It has a light guide layer made of a transparent mold material, and a diffusion sheet laid and fixed on the reflective frame.
The LED light emitting device is characterized in that a diffusion filter sheet having a thin film formed thereon is disposed on the light guide layer at a position facing each light emitting diode chip.

[Effect]

According to the LED light emitting device of the present invention, when a driving voltage is applied to the external terminal to drive each LED chip to emit light, the light emitted from each LED chip is diffused laterally in the light guide layer. , guided to a diffusion filter sheet disposed on the light guide layer. Of the light emitted from each of the LED chips, part of the light that is irradiated onto the thin film formed on the back side of the diffusion filter sheet is transmitted to the diffusion sheet side, and the rest is reflected back to the substrate side. , the light emission intensity on the surface where the thin film is formed is reduced so that it becomes almost the same as the light emission intensity around it. Furthermore, the light reflected to the substrate side is diffusely reflected on the resist applied to the surface of the substrate, and is guided to the diffusion filter sheet side again. By repeating the above steps, the unevenness of the light emission intensity in each part of the diffusion filter sheet is eliminated, and the light intensity distribution over the entire light emitting surface is made uniform. Further, the light irradiated onto the portion where the thin film is not formed is transmitted to the diffusion sheet side while maintaining the emission intensity.
Then, the light transmitted through the diffusion filter sheet while maintaining the uniform light and emission intensity is surface-emitted from the surface of the diffusion sheet, which forms the light-emitting surface, at a constant brightness and is irradiated to the outside. .

〔Example〕

An embodiment of the LED light emitting device according to the present invention will be described below with reference to the drawings.

Fig. 1 is an exploded perspective view showing an embodiment of the LED light emitting device according to the present invention, Fig. 2 is a sectional view of the LED light emitting device, and Fig. 3a is a diffusion diagram showing the main parts of the LED light emitting device. The back view of the filter sheet, FIG. 3b, is an enlarged sectional view taken along the line A--A in FIG. 3a. In the figure, reference numeral 1 indicates an LED light emitting device, and this LED light emitting device 1 consists of a substrate 2 on which a plurality of LED chips 4 are bonded on an electrode 3 on a surface 2a, and a peripheral edge 2b of the substrate 2. The formed reflective frame 5, a light guide layer 6 made of a molding material filled inside 5a of the reflective frame 5, a diffusion filter sheet 7 disposed on the light guide layer 6, It is generally constructed of a diffusion sheet 8 laid and fixed on a frame 5.

Next, each component of the above LED light emitting device is
This will be explained in detail based on the drawings in Figures 3a and 3b.

First, the substrate 2 is made of a resin material such as glass cloth epoxy resin.
A wiring pattern 9 having a predetermined shape is formed on the surface 2a, and a plurality of electrodes 3 are formed at predetermined positions of the wiring pattern 9. Further, on the electrode 3, a predetermined number of LED chips 4 and a metal thin wire 10 for short-circuiting the LED chips 4 are provided.
is bonded. By the way, the above
The LED chip 4 has a certain color tone when conducting, e.g.
It emits monochromatic light such as red, yellow, and green.

Furthermore, at the end 9a of the wiring pattern 9,
An external terminal 11 is connected to the LED chip 4 so that a driving voltage necessary for driving the LED chip 4 to emit light is applied. Further, a white resist, for example, is applied around the electrode 3, and the light from the LED chip 4 reflected by a thin film 12 formed on a diffusion filter sheet 7, which will be described later, is transferred back to the diffusion filter sheet. It is reflected to the 7 side.

Next, the reflective frame 5 has a high reflection efficiency, for example.
It is made of PBT resin and is fixedly formed on the peripheral edge 2b of the substrate 2. Further, the interior 5a of the reflective frame 5 is filled with a transparent or translucent molding material, such as an epoxy resin, to form a light guide layer 6. This light guide layer 6 protects the LED chip 4 bonded on the electrode 3, and also directs the light emitted from the LED chip 4 in the lateral direction (direction shown by arrow B in FIG. 2).
It spreads to a certain extent.

Furthermore, a diffusion filter sheet 7 is disposed on the light guide layer 6. This diffusion filter sheet 7 is made of, for example, a thin sheet of polyester, and its back surface 7a has concentric thin films 12 (in the embodiment, triple concentric circles) are formed. The formation position of this thin film 12 is based on the directivity characteristics of each LED chip 4, and is formed by vacuum-depositing A with a slightly transmittance on the back surface 7a of the diffusion filter sheet 7. be.

Next, the diffusion sheet 8 is made of the same material as the diffusion filter sheet 7, for example, polyester, and is laid and fixed on the reflective frame 5. This diffusion sheet 8 has a surface 8a serving as a light emitting surface 8b, and uniformly diffuses the light guided through the diffusion filter sheet 7.
Irradiation to the outside is performed from the light emitting surface 8b at a constant brightness.

Incidentally, there is an air layer 13 between the diffusion sheet 8 and the diffusion filter sheet 7, and due to the difference in refractive index with the light guide layer 6 made of epoxy resin, the diffusion of light emitted from the LED chip 4 is reduced. This makes it even more effective.

Furthermore, the inner surface 5b of the reflective frame 5 between the diffusion sheet 8 and the diffusion filter sheet 7 is inclined outward at an angle θ, and the light emitted from the LED chip 4 is transmitted to the LED light emitting device. The light is efficiently reflected to the front and peripheral parts of the 1.

Next, the manufacturing method and operation of the LED light emitting device configured as described above will be explained.

First, a wiring pattern 9 having a predetermined shape is formed on the surface 2a of the substrate 2, and a plurality of electrodes 3 are formed at predetermined positions on the wiring pattern 9. And the electrode 3
For example, a white resist is applied around the area 3a.
Next, a predetermined number of LED chips 4 and thin metal wires 10 are bonded onto the electrode 3, and an external terminal 11 is connected to the end 9a of the wiring pattern 9. Then, the reflective frame 5 is fixed onto the substrate 2, and the interior 5a of the reflective frame 5 is filled with a transparent or translucent molding material to form the light guide layer 6. Next, a diffusion filter sheet 7 having a thin film 12 formed on its surface 8a is arranged and fixed on the light guide layer 6. Further, a diffusion sheet 8 is laid and fixed on the reflective frame 5.

LED light emitting device 1 completed as described above
, applying a driving voltage to the external terminal 11,
Each LED chip 4 is driven to emit light. Then,
The light emitted from each LED chip 4 is evenly diffused in the lateral direction in the light guide layer 6 and guided to the diffusion filter sheet 7. Then, in the diffusion filter sheet 7, each
Of the light emitted from the LED chip 4, the thin film 12 formed on the back surface 7a of the diffusion filter sheet 7
A part of the light irradiated onto the surface is transmitted to the diffusion sheet 8 side, and the other part is reflected back to the substrate 2 side, which reduces the emission intensity on the surface where the thin film 12 is formed, and reduces the emission intensity around it. I'm trying to make it almost the same. Furthermore, the light reflected toward the substrate 2 side is efficiently diffusely reflected on the resist applied to the surface 2a of the substrate 2, and is again diffused by the diffusion filter sheet 7.
It is reflected and irradiated to the side. By repeating the above, each part (diffusion filter sheet 7
The unevenness of the light emission intensity on the light emitting surface is eliminated, and the light intensity distribution over the entire light emitting surface is made uniform. Further, the light irradiated onto the portion where the thin film 12 is not formed is transmitted to the diffusion sheet 8 side while maintaining the emission intensity. Then, the light transmitted through the diffusion filter sheet 7 while maintaining the uniform light and emission intensity is guided to the diffusion sheet 8 and is then passed through the reflection frame 5.
The surface 8 of the diffusion sheet 8 that is also efficiently reflected in the front peripheral portion of the LED light emitting device 1 and forms the light emitting surface 8b.
It emits surface light at a constant brightness from a, is irradiated to the outside, and is used as a light source for an indicator light or a liquid crystal display device.

In the above-mentioned embodiment, the thin film 12 formed on the back surface 7a of the diffusion filter sheet 7 is formed in triple concentric circles, but the invention is not limited to this, and for example, as shown in FIG. The size of the thin film 22 formed on the back surface 7a of the diffusion filter sheet 7 may be made smaller as the distance from the position corresponding to . Further, as shown in FIG. 5, the size of the thin film 32 is kept constant, and the thin film 32 is spread on the diffusion filter sheet 7 in a dense manner at a position corresponding to the LED chip 4 and becomes sparse as the distance from the LED chip 4 increases. It may be formed on the back surface 7a of the. Furthermore, the thin films 12, 22, and 32 may have shapes other than those described above, and the number and width of the thin films 12, 22, and 32 may be arbitrarily determined depending on the degree to which the emission intensity is reduced.

[Effect of idea]

As explained above, the LED light emitting device according to the present invention has a structure in which a diffusion filter sheet with a thin film formed thereon is disposed on the light guide layer at a position facing each LED chip, so that the entire device is thin. In addition to reducing the mounting area, it also makes it possible to equalize the intensity distribution of the light emitted from each LED chip on the light emitting surface, and because it emits surface light at a constant brightness, it can be used as an indicator lamp or liquid crystal display device. It is ideal as a light source for etc.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing an embodiment of the LED light emitting device according to the present invention, Fig. 2 is a sectional view of the LED light emitting device, and Fig. 3a is a diffusion diagram showing the main parts of the LED light emitting device. The back view of the filter sheet, FIG. 3b, is an enlarged sectional view taken along line A-A in FIG. 3a, FIG.
FIG. 5 is a diagram showing a diffusion filter sheet on which a thin film of another shape is formed. DESCRIPTION OF SYMBOLS 1... LED light emitting device, 2... Substrate, 3... Electrode, 4... Light emitting diode chip (LED chip), 5... Reflective frame, 6... Light guide layer,
7... Diffusion filter sheet, 8... Diffusion sheet,
12...Thin film.

Claims (1)

[Claims for Utility Model Registration] (1) A substrate with a plurality of light emitting diode chips bonded onto electrodes on its surface, a reflective frame formed on the peripheral edge of the substrate, and an interior of the reflective frame. a light guide layer made of a transparent or translucent molding material filled with a light guide layer, and a diffusion sheet laid and fixed on the reflective frame.
1. An LED light emitting device, wherein a diffusion filter sheet having a thin film formed thereon is disposed on the light guide layer at a position facing each light emitting diode chip. (2) The LED light emitting device according to claim 1, wherein the thin film is formed by A vapor deposition.