JP2005026101A - Surface light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface light-emitting device with improved brightness, prevented from lowering of reliability. <P>SOLUTION: The surface light-emitting device is composed of: a light guide plate having planar parts on both surfaces; a semiconductor light-emitting device housed in a notched part formed at a side part of the light guide plate, having light-emitting surfaces arranged so as to face light incident surfaces of the notched part; a flexible base plate arranged on the planar part at one side of the light guide plate, on which the semiconductor light-emitting device is mounted; and an adhesive layer formed between the light-emitting surface of the semiconductor light-emitting device and the light incident surface. The planar part and the flexible base plate are stuck by a double-side adhesive tape. In forming the adhesive layer, an adhesive before solidified being about to intrude between the flexible base plate and the light guide plate is intercepted by the double-side adhesive tape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light source for backlight that illuminates an image display unit using, for example, liquid crystal from the back side.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an image display unit using liquid crystal has been adopted in electronic devices such as mobile phones and digital cameras. This image display unit uses a light source (surface light emitting device) in which side view type LEDs (light emitting diodes) are adjacently arranged on the side surface of a light guide plate as a backlight (see, for example, Patent Document 1). Light emitted from the LED enters the light guide plate through the side surface, is reflected by the back surface of the light guide plate, and is emitted from the front surface to the outside.
[0003]
[Patent Document 1]
JP 2002-90735 A (Page 2-5, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, with the thinning of the light guide plate and the miniaturization of the LED, the relative position between the light guide plate and the LED tends to shift, and it has become difficult to incorporate light from the LED into the light guide plate without loss.
[0005]
Here, in order to prevent this displacement, it is conceivable to fix the light guide plate and the LED by bonding. In this case, since the light emitted from the LED enters the light guide plate without passing through the air layer, the light loss at the interface is reduced and the luminance is improved.
[0006]
However, the adhesive before solidification has fluidity, so it is difficult to adhere to a predetermined range, and it adheres outside the adhesion range and affects the reliability of electronic components, or enters into fine gaps. There is a problem of solidifying and deforming the outer shape of the product.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a surface light emitting device that improves luminance and prevents a decrease in reliability.
[0008]
[Means for Solving the Problems]
In the surface light emitting device of the present invention, a surface light emitting device is provided with an adhesive layer between the semiconductor light emitting device and the light guide plate, and the planar portion of the light guide plate and the flexible substrate on which the semiconductor light emitting device is mounted are fixed by a double-sided tape. It is a device.
[0009]
According to the present invention, it is possible to obtain a surface light emitting device that improves luminance and prevents a decrease in reliability.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 is housed in a light guide plate having flat portions formed on both sides and a notch formed in a side portion of the light guide plate, and the light emitting surface faces the light incident surface in the notch. The semiconductor light emitting device disposed, the flexible substrate mounted on the one planar portion of the light guide plate with the semiconductor light emitting device mounted thereon, and formed between the light emitting surface and the light incident surface of the semiconductor light emitting device The planar portion and the flexible substrate are provided with an adhesive layer, the surface light emitting device being fixed by a double-sided tape, and when forming the adhesive layer, the flexible substrate It has the effect | action of damming up the adhesive agent before solidification which is going to infiltrate between a light guide plate with a double-sided tape.
[0011]
The invention according to claim 2 is the surface light-emitting device according to claim 1, wherein the double-sided tape is attached to surround the three sides of the semiconductor light-emitting device. This has the effect of preventing the adhesive from entering between the flexible substrate and the light guide plate from the portions adjacent to both sides of the light incident surface.
[0012]
According to a third aspect of the present invention, the double-sided tape has a cutout portion corresponding to the cutout portion, and two sides of the cutout portion adjacent to the light incident surface are arranged in the cutout portion. 3. The surface light emitting device according to claim 2, wherein the adhesive filled in the notch flows laterally and the adhesive enters between the flexible substrate and the light guide plate. This has the effect that it is surely prevented.
[0013]
According to a fourth aspect of the present invention, the light guide plate and the semiconductor light emitting device are held by a holder that covers the back surface of the light guide plate, and the holder covers an opening formed on a side of the notch. 4. The surface light emitting device according to claim 2, further comprising a side wall portion, wherein the adhesive layer is formed so as to cover an entire circumference of the semiconductor light emitting device. And a notch in the light guide plate surround the four sides of the semiconductor light-emitting device to form a chamber in which adhesive can be injected. When injecting the adhesive, the double-sided tape and holder that surrounds the three sides of the semiconductor light-emitting device are bonded. The agent can be prevented from leaking, and the adhesive layer covers the entire periphery of the semiconductor light emitting device, so that the adhesive strength is improved.
[0014]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
[0015]
(First embodiment)
FIG. 1 is a partial plan view of a surface light emitting device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA ′ of the surface light emitting device. As shown in FIG. 1, a surface light emitting device 1 according to the present invention includes a rectangular plate-shaped light guide plate 2 made of a synthetic resin such as polycarbonate or acrylic, and a surface-mount type side-view type semiconductor mounted on a flexible substrate 3. A light emitting device 4 and an adhesive layer 5 formed by solidifying a translucent adhesive formed between the light guide plate 2 and the semiconductor light emitting device 4 are provided. As an adhesive used to form the adhesive layer 5, for example, a visible light curable material can be used, but any other UV resin or thermosetting material can be used as long as it has translucency. Can be used.
[0016]
The light guide plate 2 has flat portions 7 and 8 formed on both the front and back surfaces, and has notches 9 formed at two locations on one side.
[0017]
The notch 9 is formed so as to open to the side and penetrate in the vertical direction, and to have an end face that is U-shaped in plan view. An end surface formed in parallel with one side surface of the light guide plate 2 is a light incident surface 10 on which light from the semiconductor light emitting device 4 is incident.
[0018]
The semiconductor light emitting device 4 is housed in the notch 9 and has a light emitting surface disposed opposite to the light incident surface 10. In addition, the flexible substrate 3 on which the semiconductor light emitting device 4 is mounted is arranged on the flat portion 7 on the front side of the light guide plate 2 so as to cover the notch portion 9.
[0019]
The surface on the light guide plate 2 side of the flexible substrate 3 and the flat portion 7 on the front side of the light guide plate 2 are fixed by a double-sided tape 11, respectively. The double-sided tape 11 uses, for example, a base material made of PET (polyethylene terephthalate) coated with an acrylic adhesive material, has a thickness of about 0.060 mm, and is excellent in heat resistance and electrical insulation. Yes.
[0020]
The double-sided tape 11 is formed with a cutout portion 12 cut in a U shape so that the cutting line surrounds three sides of the semiconductor light emitting device 4, and the opening side of the cutout portion 12 is connected to the cutout portion 9 of the light guide plate 2. They are arranged in the same direction. Further, the outer shape of the double-sided tape 11 other than the cut-out portion 12 is formed slightly smaller than the outer shape of the flexible substrate.
[0021]
The cutout portion 12 of the double-sided tape 11 does not completely coincide with the cutout portion 9 of the light guide plate 2, and the side of the cutout portion 12 corresponding to the light incident surface 10 is closer to the light guide plate 2 than the light incident surface 10. Two sides of the cutout portion 12 that is disposed on the main body side and adjacent to the light incident surface 10 are disposed in the cutout portion 9 of the light guide plate 2.
[0022]
In addition, it is also possible to form so that each side of the cut-out part 12 of the double-sided tape is all disposed in the cut-out part 9 of the light guide plate 2. In this case, the adhesive penetrates between the double-sided tape and the light guide plate 2 and expands to prevent the surface light emitting device from becoming thick, and a product with a uniform size can be manufactured. .
[0023]
Moreover, it is also possible to form so that each side of the cut-out part 12 of the double-sided tape is arranged outside the cut-out part 9 of the light guide plate 2. In this case, since the gap between the double-sided tape and the semiconductor light emitting device is increased, the adhesive of the double-sided tape is prevented from adhering to the semiconductor light emitting device when the double-sided tape is attached to the flexible substrate 3, Workability is improved.
[0024]
An adhesive layer 5 is formed in the gap between the light emitting surface of the semiconductor light emitting device 4 and the light incident surface 10 of the light guide plate 2. The adhesive layer 5 is formed by solidifying a translucent adhesive.
[0025]
The adhesive is filled between the light emitting surface of the semiconductor light emitting device 4 and the light incident surface 10 of the light guide plate 2, and further solidifies in a state of protruding slightly to the side of the semiconductor light emitting device 4 to form the adhesive layer 5. To do. Since the double-sided tape 11 is provided so as to surround the three sides of the semiconductor light emitting device 4, the adhesive does not leak out from between the flexible substrate 3 and the light guide plate 2 to the outside of the notch portion 9.
[0026]
The light guide plate 2 forms a minute uneven pattern (not shown) on the flat portion 8 on the back side, and a reflection sheet (not shown) is provided on the flat portion 8 on the back side to diffuse light (not shown). 2) and a prism sheet (not shown) for condensing light is provided on the flat portion 7 on the front side. The diffusion sheet and the prism sheet are provided at a distance of about 3 mm from the semiconductor light emitting device 4 side end of the light guide plate 2 in order to avoid interference with the flexible substrate 3. With this configuration, light incident on the light guide plate 2 from the semiconductor light emitting device 4 via the adhesive layer 5 and the light incident surface 10 is reflected to the front side by the uneven pattern and the reflection sheet on the back surface of the light guide plate 2, and this light. Is diffused and condensed by the diffusion sheet and the prism sheet, so that the surface of the light guide plate 2 can emit light uniformly.
[0027]
(Second Embodiment)
FIG. 3 is a plan view of the surface emitting device according to the second embodiment. In the surface light-emitting device 14 of the second embodiment, the surface light-emitting device 1 of the first embodiment described above is provided with a holder 15 that holds the light guide plate 2 and the semiconductor light-emitting device 4. Accordingly, the same members are denoted by the same reference numerals and description thereof is omitted.
[0028]
The holder 15 is formed by bending a single metal plate made of a metal material such as SUS304, connected to one side of the rectangular bottom plate 16, and has an opening formed on the side of the notch 9 of the light guide plate 2. The side surfaces of the light guide plate 2 are held by side plates 18 to 20 that are connected to the other three sides of the plate-like side wall portion 17 and the bottom plate 16 to cover the other side surfaces of the light guide plate 2. A substantially rectangular through-hole 24 for injecting adhesive into the notches 9 is formed at the end of the bottom plate 16 on the side wall 17 side.
[0029]
Attachment plate parts 21 and 22 for fixing to the main body part (not shown) are connected to the side plates 18 and 20 arranged to face each other. Further, fixing portions such as hooking pieces for attaching the light guide plate 2 are formed at a plurality of locations on the side plates 18 to 20.
[0030]
When injecting the adhesive, the adhesive is injected from the through hole 24 with the back surface facing upward. Since the periphery of the semiconductor light emitting device 4 is formed in a rectangular container shape by the cutout portion 9 of the light guide plate 2, the flexible substrate 3, and the side wall portion 17 of the holder 15, a rectangular parallelepiped covering the entire circumference of the semiconductor light emitting device 4 A shaped adhesive layer 23 can be formed.
[0031]
Since the adhesive layer 23 is formed so as to cover the entire circumference of the semiconductor light emitting device 4, light leaked laterally from the semiconductor light emitting device 4 is guided from a surface other than the light incident surface 10 of the cutout portion 9. 2 and the bonding strength between the semiconductor light emitting device 4 and the light guide plate 2 is improved. Since the lower part of the adhesive layer 23 is surrounded by the double-sided tape 11 formed in a U-shape and the side wall part 17, the adhesive does not leak out.
[0032]
It is also possible to dispose the flexible substrate 3 on the bottom plate 16 side of the holder 15 and omit the through hole 24. In this case, the adhesive is injected from the front side.
[0033]
【The invention's effect】
As described above, according to the present invention, since the flat portion of the light guide plate and the flexible substrate are fixed by the double-sided tape, when the adhesive layer is formed, an attempt is made to enter between the flexible substrate and the light guide plate. The adhesive before solidification is dammed with a double-sided tape, and the luminance can be improved while preventing a decrease in the reliability of the apparatus.
[0034]
In addition, when the double-sided tape is attached to surround the three sides of the semiconductor light emitting device, it prevents the adhesive from entering between the flexible substrate and the light guide plate from the part adjacent to both sides of the light incident surface in the notch. Thus, the reliability of the apparatus can be improved.
[0035]
Also, if the two sides of the cut-out part adjacent to the light incident surface are placed in the cut-out part, the adhesive filled in the cut-out part flows sideways and enters the gap between the flexible substrate and the light guide plate This is surely prevented, and the reliability of the apparatus can be further improved.
[0036]
In addition, when the adhesive layer that covers the entire periphery of the semiconductor light emitting device is formed by covering the opening formed on the side of the notch with the side wall of the holder that holds the light guide plate, the adhesive layer is formed. When injecting adhesive into the semiconductor light-emitting device, the adhesive can be prevented from leaking by the double-sided tape and holder that surrounds the three sides of the semiconductor light-emitting device, and the adhesive layer covers the entire circumference of the semiconductor light-emitting device, improving the adhesive strength In addition, the reliability of the semiconductor light emitting device is improved.
[Brief description of the drawings]
FIG. 1 is a partial plan view of a surface light emitting device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA ′ of the surface light emitting device. Plan view [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Surface light-emitting device 2 Light-guide plate 3 Flexible board 4 Semiconductor light-emitting device 5 Adhesive layer 7 Plane part 8 Plane part 9 Notch part 10 Light incident surface 11 Double-sided tape 12 Cut-out part 14 Surface light-emitting device 15 Holder 16 Bottom plate 17 Side wall part 18 -20 Side plate 21, 22 Mounting plate part 23 Adhesive layer 24 Through hole

Claims (4)

A light guide plate having flat portions on both sides, and
A semiconductor light emitting device housed in a notch formed on the side of the light guide plate and having a light emitting surface opposed to the light incident surface in the notch;
A flexible substrate mounted with this semiconductor light emitting device and disposed on one of the planar portions of the light guide plate,
An adhesive layer formed between the light emitting surface of the semiconductor light emitting device and the light incident surface;
The planar light emitting device, wherein the flat portion and the flexible substrate are fixed by a double-sided tape. The surface light-emitting device according to claim 1, wherein the double-sided tape is stuck around three sides of the semiconductor light-emitting device. The double-sided tape has a cutout portion corresponding to the cutout portion, and two sides of the cutout portion adjacent to the light incident surface are disposed in the cutout portion. 2. The surface light-emitting device according to 2. The light guide plate and the semiconductor light emitting device are held by a holder that covers a back surface of the light guide plate, and the holder includes a side wall portion that covers an opening formed on a side of the notch portion, and the adhesive layer The surface light-emitting device according to claim 2, wherein the surface light-emitting device is formed so as to cover the entire circumference of the semiconductor light-emitting device.

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