JP2008071696A - Surface-mounted light-emitting diode and plane light-emitting device using the same on its side surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin plane light-emitting device in which luminance deterioration is prevented and a surface-mounted light-emitting diode which can be used as a light source for the plane light-emitting device. <P>SOLUTION: In the light source for the plane light-emitting device, the light source is a surface-mounted light-emitting diode having a substrate, a width of a plane of the substrate where the light-emitting diode element is mounted is larger than a width in a thickness direction of an incident face of the plane light-emitting device, and the surface-mounted light-emitting diode has a reflecting layer and emission light of the light-emitting diode element is reflected by the reflecting layer and then emitted from the surface-mounted light-emitting diode. In a plane light-emitting device having the surface-mounted light-emitting diode as a light source and a light guide plate, the substrate surface where the light-emitting diode element is mounted is inclined against the light guide plate and a width in a thickness direction of the surface-mounted light-emitting diode is made almost equal to a thickness of the light guide plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface-mounted light-emitting diode light source for a surface light-emitting device and a surface light-emitting device using the same on a side surface.

Recently, thinning of display devices is progressing rapidly, and this tendency is particularly remarkable in portable devices such as mobile phones.
In a light-receiving display device such as a liquid crystal, it is common to illuminate a display unit with a surface light-emitting device, but the surface light-emitting device is also becoming thinner.
The problem is the thickness of the light-emitting diode that is the light source of the surface light-emitting device, and the thickness of the light guide plate constituting the surface light-emitting device is rapidly reduced. This is because it is not easy because it tends to cause a decrease.

A light emitting diode element is mounted on a substrate of a conventional surface mount type light emitting diode, and the width in the thickness direction of the light incident surface of the surface light emitting device is larger than the width of the surface of the substrate on which the light emitting diode element is mounted, That is, the thickness of the light guide plate is greater or the two are equal.
FIG. 3A shows such a conventional surface light emitting device.
In FIG. 3, 110 is a light guide plate, 114 is a diffuser plate for diffusing the light emitted from the light guide plate, 116 and 118 are prism sheets, and the ridge lines of the prisms at 116 and 118 are almost orthogonal to each other and perpendicular to the surface light emitting device. It works to collect light in any direction. Reference numeral 112 denotes a reflection plate provided at the lower portion of the light guide plate 110, which functions to return light emitted from the light guide plate 110 to the lower portion to the light guide plate 110.

Reference numeral 100 denotes a surface mount type light emitting diode, in which a light emitting diode element 104 is mounted on a substrate 106, and an electrode connected to the light emitting diode element 104 is formed on a part 108 of the substrate and mounted on the substrate 106. The light emitting diode element 104 was sealed and protected by a transparent resin 102.
In the following drawings, the same members are denoted by the same numbers.

The surface light emitting device illuminates a light receiving display device such as a liquid crystal display device disposed on the light guide plate 110 with such a structure.
Lk1 is the width of the surface of the substrate 106 on which the light emitting diode element 104 is mounted, and Ld1 is the width in the thickness direction of the light incident surface of the surface light emitting device, that is, the thickness of the light guide plate 110 when the light source is disposed on the side surface. is there.
Conventionally, as shown in FIG. 3A, since Ld1 is larger than Lk1, almost all of the light emitted from the surface-mounted light emitting diode 100 as the light source is incident on the light guide plate as shown by the thick line. Light utilization efficiency was high.

However, in order to reduce the thickness of the surface light emitting device, the light guide plate having the thickest thickness among the components of the surface light emitting device has been thinned. However, since it is not easy to reduce the thickness of the light emitting diode, as shown in FIG. 3B, the thickness Lk2 of the emission surface of the light emitting diode, more precisely, the width Lk2 of the surface of the substrate 106 on which the light emitting diode element 104 is mounted. However, the thickness Ld2 in the thickness direction of the light incident surface of the surface light emitting device 200, that is, the thickness Ld2 of the light guide plate 110 when the light source is arranged on the side surface, becomes thicker.
When Lk2 is larger than Ld2, there is a problem that, as illustrated by a thick line, the amount of light that is not incident on the light guide plate out of the light emitted from the surface-mounted light-emitting diode 100 that is a light source increases, and the light use efficiency decreases. It was.

  In order to avoid such problems, it is considered that a reflection layer is provided around the resin that seals the light emitting diode element, and the direction of light emitted from the light emitting diode is narrowed to increase the amount of light incident on the light guide plate. It was. This technique is referred to as a second conventional technique.

4 and 5 are diagrams for explaining the second prior art.
4A is a perspective view of a light emitting diode according to the second prior art, FIG. 4B is a perspective view of a surface light emitting device using the light emitting diode of FIG. 4A, and FIG. 5A is a light emitting diode. FIG. 5B is a sectional view of a surface light emitting device using the light emitting diode of FIG.
4A and 5A, the light-emitting diode 122 is provided with a reflective layer 124 indicated by oblique lines on the upper and lower surfaces and the left and right side surfaces of the sealing resin 102. The directivity of light emitted from the surface-mounted light-emitting diode is regulated.

In the surface light emitting device 210 in FIGS. 4B and 5B, the light emitting diode 122 is disposed on the side surface of the thin light guide plate 126.
As a result of configuring the surface light emitting device 210 as described above, the width Ld3 in the thickness direction of the light incident surface of the surface light emitting device, that is, the thickness Ld3 of the light guide plate 110 and the width Lk3 of the surface of the substrate 106 on which the light emitting diode element 104 is mounted. There is an effect that high light utilization efficiency can be maintained even if is substantially equal.

However, when the thickness of the light guide plate is smaller than the width of the surface of the substrate 106 on which the light emitting diode element 104 is mounted, there remains a problem that the light use efficiency decreases.
For example, the thickness of a general light guide plate used for a mobile phone or the like is 0.5 to 1.0 mm, but it is necessary to use a light guide plate having a thickness of 0.05 to 0.3 mm. There is a problem that high light utilization efficiency cannot be maintained for a thin light guide plate.

In order to solve such a problem, a light guide plate in which only an end portion which is a light incident portion of the light guide plate is made sufficiently thicker than the thickness of the light emitting source is used to prevent light source light from leaking from the light guide plate, and the light guide plate In order to prevent light leakage from the light, there is a proposal to set the angle of inclination of the end portion to 13 ° or less (see, for example, Patent Document 1).
However, this proposal has a problem that the light incident on the light guide plate is easily emitted on the light source side of the light guide plate, so that the brightness of the surface light source is not uniform.

In addition, when using a light guide plate with thickened end portions that are light incident portions of the light guide plate for each different color, and assembling as a lighting device, avoid thickening the lighting device by stacking so that the thick end portions do not overlap. There is also a proposal (see, for example, Patent Document 2).
However, especially in small portable devices, it is impossible to provide light guide plates in different colors from the viewpoint of thickness and cost, and the width of the lighting device is increased by stacking so that the thick ends do not overlap. There was a problem that it would become a fatal fault.

Furthermore, there is also a proposal to use a hot cathode tube as a light source in order to increase the light emission rate (see, for example, Patent Document 3).
Since the tube diameter of the hot cathode tube is larger than that of the cold cathode tube, the tube diameter of the light source is relatively larger than the thickness of the light guide plate, and the light source light leaks. A reflector is provided along the aperture, and the aperture of the reflector is narrowed to make the width of the aperture and the thickness of the light guide plate substantially equal.

However, the content of the countermeasure seems to be a list of known technologies.
In addition, paragraph number 0022 in this proposal includes a description that nullifies the effect of the proposal content “the opening angle only needs to be in the range of 90 ° to 180 °”.
In order to prevent light source light from leaking, the aperture angle must be reduced. However, as the aperture angle is reduced, the reflector provided in the tubular light source becomes nearly perpendicular to the light source near the aperture. . As a result, there is also a problem caused by the light source shape in which the light is absorbed while it is repeatedly reflected and the illumination light rate decreases.

That is, the technique using a tubular light source as in Patent Document 3 is considered to be unsuitable for portable devices that require the use of a very thin light guide plate.
Such a difference is a problem that arises because different products are applied. For example, it is important to increase the luminance even if the illumination device for a liquid crystal device used for television display is relatively thick, such as a mobile phone. The difference is that thinning and downsizing are the most important issues for lighting devices for liquid crystal devices used for display of small portable devices.

JP 2004-265797 A JP-A-2005-347052 JP 2006-24472 A

  It is difficult to realize a thin surface light-emitting device that prevents a decrease in luminance and a surface-mounted light-emitting diode that can be used as a light source of the surface light-emitting device.

  The surface-mounted light-emitting diode of the present invention is a light source for a surface-emitting device having a substrate, and the light-emitting diode element is mounted on the substrate as a light-emitting element in the surface-mounted light-emitting diode. The width of the surface of the substrate that is mounted is larger than the width in the thickness direction of the light incident surface of the surface light emitting device, and the resin that seals the light emitting diode element on the substrate has a substantially triangular prism shape, and the surface The mounting type light emitting diode has a reflection layer, and the light emitted from the light emitting diode element is reflected by the reflection layer and then emitted from the surface mounting type light emitting diode.

  The surface-mounted light-emitting diode according to the present invention has the light-emitting diode element mounted on one surface of the triangular prism-shaped sealing resin, and the reflective surface is provided on the other surface. Is a light emitting surface.

  The surface-mounted light-emitting diode according to the present invention is a light source for a surface-emitting device having a substantially square columnar substrate, and the surface-mounted light-emitting diode has a light-emitting diode element mounted on the substrate as a light-emitting element. The width of the surface of the substrate on which the light emitting diode element is mounted is larger than the width in the thickness direction of the light incident surface of the surface light emitting device, and the resin sealing the light emitting diode element on the substrate is substantially triangular. It is columnar, one of the three surfaces of the triangular prism is in contact with the light emitting diode element, the other one is provided with a reflective layer, and the third surface is the light emitting surface of the light emitting diode element, Of the four surfaces of the substantially quadrangular prism-shaped substrate, two surfaces are substantially parallel to the reflective layer, and one of the two surfaces is on the same plane as the reflective layer. One of the two faces is the 2 Surface and a substantially right angle of the surface on which the light emitting diode element is mounted out of the four faces is characterized in that it is set to be an oblique angle relative to the reflective layer.

  The surface light-emitting device of the present invention includes a light-emitting plate that uses a surface-mounted light-emitting diode as a light source, and provides light to the light-receiving device placed on the upper surface. The width of the surface of the substrate on which the light emitting diode element is mounted is larger than the thickness of the light guide plate, and the substrate surface on which the light emitting diode element is mounted is inclined with respect to the light guide plate. Thereby, the width in the thickness direction of the surface-mounted light-emitting diode and the thickness of the light guide plate are made substantially equal.

  The surface light-emitting device of the present invention is characterized by using the surface-mounted light-emitting diode described above.

  According to the present invention, it is possible to realize a thin surface light-emitting device that prevents a reduction in luminance and a surface-mounted light-emitting diode that can be used as a light source of the surface light-emitting device.

  In a light source for a surface light-emitting device used for a so-called light-receiving device that uses external light, the light source is a surface-mounted light-emitting diode having a substrate, and the surface-mounted light-emitting diode has a light-emitting element on the substrate. The surface of the substrate on which the light emitting diode element is mounted is larger than the width in the thickness direction of the light incident surface of the surface light emitting device, and the light emitting diode is mounted on the substrate. The resin that seals the element has a substantially triangular prism shape, and the surface-mounted light-emitting diode has a reflective layer, and the light emitted from the light-emitting diode element is reflected by the reflective layer and then emitted from the surface-mounted light-emitting diode. Is done.

  The surface light-emitting device of the present invention uses a surface-mounted light-emitting diode as a light source, has a light guide plate, illuminates a light-receiving display device placed on an upper surface, and the substrate surface on which the light-emitting diode element is mounted By tilting with respect to the light guide plate, the width in the thickness direction of the surface-mounted light-emitting diode and the thickness of the light guide plate were made substantially equal.

  Hereinafter, the present invention will be described based on examples.

1A and 1B are diagrams for explaining a first embodiment of a surface-mounted light-emitting diode according to the present invention. FIG. 1A is a sectional view and FIG. 1B is a perspective view.
FIG. 1A is a cross-sectional view of a surface-mounted light-emitting diode 10 according to the present invention. A light-emitting diode element 22 is mounted on one surface of a substrate 12, and a portion 14 of the substrate 12 is connected to the light-emitting diode element 22. The light emitting diode element 22 is sealed and protected by a substantially triangular prism-shaped transparent resin 24. Reference numeral 16 denotes a reflective layer. As indicated by a thick line in FIG. 1B, the light emitted from the light emitting diode element 12 is reflected by the reflective layer 16 and then emitted from the surface-mounted light emitting diode 10. The reflective layer 16 is preferably white or silver in order to improve the reflection efficiency.

  In addition, one of the three faces of the substantially triangular prism-shaped sealing resin 24 is in contact with the light emitting diode element 22, and the other one face is provided with the reflective layer 16, and the third face is the light emitting diode. Of the four surfaces of the substantially quadrangular prism-shaped substrate 12, two surfaces are substantially parallel to the reflective layer 16, and one of the two surfaces is the reflective layer 16. The other surface of the four surfaces forms an angle substantially perpendicular to the two surfaces, and the surface of the four surfaces on which the light emitting diode element is mounted is the reflective layer 16. Is set to be at an oblique angle.

Lk4 is the width of the surface of the substrate 12 on which the light emitting diode element 12 is mounted. The premise of the present invention is that Lk4 is larger than the width in the thickness direction of the light incident surface of the surface light emitting device using the light emitting diode 10 as a light source, that is, the thickness of the light guide plate.
The resin 24 that seals the light emitting diode element 22 is a substantially triangular prism-like transparent resin, and its upper surface and side surfaces are covered with a reflective layer 16 as shown in FIG. Accordingly, when viewed from the cross-sectional view of FIG. 1A, the light emitting diode element 22 is mounted on one surface of the triangular prism-shaped sealing resin 24, and the reflective layer 16 is provided on the other surface. The third surface is a light emitting surface. Therefore, the surface of the substrate 12 on which the light emitting diode element 22 is mounted is inclined with respect to the reflective layer 16.

  The light emitted from the light emitting diode element 22 is emitted from the surface-mounted light emitting diode 10 after being reflected by the reflective layer 16 as indicated by a thick line in FIG. The width Lk4 of the surface of the substrate on which the light emitting diode element is mounted is larger than the thickness of the light guide plate, and the surface of the substrate 12 on which the light emitting diode element 22 is mounted is inclined with respect to the reflective layer 16. As a result, it is possible to make the surface light source thin by making the width T1 in the thickness direction of the surface-mounted light emitting diode substantially equal to the thickness of the light guide plate.

2A and 2B are diagrams for explaining a first embodiment of the surface light emitting device according to the present invention. FIG. 2A is a cross-sectional view and FIG. 2B is a perspective view.
In FIG. 2A, 28 is a light guide plate, 114 is a diffuser plate for diffusing the light emitted from the light guide plate, 116 and 118 are prism sheets, and the ridge lines of the prisms at 116 and 118 are almost orthogonal, and surface emission It works to collect light in the direction perpendicular to the device.
The reflection plate 26 is disposed under the light guide plate 28 and functions to return light leaked downward from the light guide plate 28 into the light guide plate 28.
Most of the light emitted from the third surface of the surface-mounted light emitting diode 10 toward the light guide plate 28 is in the X-axis direction, that is, in the light emitting region in the light guide plate 28 as shown by the thick line in FIG. Led.
The surface light emitting device 11 of the present invention illuminates a light receiving type display device such as a liquid crystal display device arranged in the upper direction of the light guide plate 28 with such a structure, or gives emitted light to a push button such as a keypad. To do.

The light emitting diode element 22 is mounted on one surface of the sealing resin 24 of the surface mount type light emitting diode 10, the reflective layer 16 is provided on the other surface, and the third surface is a light emitting surface. It has become. Lk4 is the width of the surface of the substrate 12 on which the light emitting diode element 12 is mounted. Lk4 is larger than the thickness Ld4 of the light guide plate.
The surface-mounted light-emitting diode 10 is disposed on the side surface of the light guide plate 28 so that the reflective layer 16 of the surface-mounted light-emitting diode 10 and the upper surface of the light guide plate 28 are substantially parallel to each other. The surface of the substrate 12 is inclined with respect to the 28 light guide plate.

  In the first embodiment, the light emitting surface of the surface-mounted light emitting diode 10 and the end surface with which the light emitting diode 10 is in contact with each other have an inclination and are in contact with each other as shown in the drawing. It is comprised so that the upper surface of this may become substantially parallel. That is, the two are paired, and the light emitting surface of the surface-mounted light emitting diode 10 and the light incident surface of the light guide plate 28 are set in parallel. By comprising in this way, the loss of the light in the coupling | bond part of a light source and a light-guide plate can be suppressed, and the light utilization efficiency can be improved.

With this configuration, the width Lk4 of the substrate surface on which the light emitting diode element 22 is mounted is larger than the thickness Ld4 of the light guide plate 28, but the width T1 in the thickness direction of the surface mounted light emitting diode 10 is larger than Lk4. Since it can be made smaller, T1 and Ld4 are made substantially equal, and the surface light source can be made thinner. Further, since there is no problem even if Lk4 is larger than Ld4, it is possible to use a light-emitting diode element having a large light emission amount, a thin surface light-emitting device that prevents a decrease in luminance, and a surface-mount type that can be used as a light source of the surface light-emitting device. A light-emitting diode was realized.
In addition, since the end portion of the light guide plate 30 is not set to be thick in this way, the light incident on the light guide plate is easily emitted on the light source side of the light guide plate, and the problem of uneven brightness of the surface light source can be solved. ing.

In the present specification, the surface mount type light emitting diode 10, the surface mount type light emitting diode 10, the light guide plate 28, the diffusion plate 114, and the prism sheet 116 are configured by the substrate 12, the light emitting diode element 22, and the sealing resin 24. , 118 and the reflection plate 26 is defined as a surface light emitting device 11. The diffuser plate 114, the prism sheets 116, 118, and the like may belong to the illuminated light receiving display device, and the reflective plate 26 may belong to the housing. These are the light emitting diode 10 and the light guide plate 28.
Further, the sheets 114, 116, and 118 can have different configurations.

Furthermore, in the present embodiment, an example in which the light emitting surface of the surface-mounted light emitting diode 10 and the end surface of the light guide plate in contact with the light emitting diode 10 are inclined with respect to each other is given. For example, the end surface of the light guide plate is parallel to the Z axis. It can also be considered. In this way, the light use efficiency is slightly reduced, but the light guide plate can be made at low cost.
Furthermore, it is conceivable that the third surface of the surface-mounted light emitting diode 10 is also parallel to the Z axis. In such a case, it is desirable that the reflective layer 16 be a reflective sheet, for example, to have a size that covers from the surface-mounted light emitting diode 10 to the end region of the light guide plate 28.

In addition, although the thickness of the general light guide plate conventionally used for a mobile phone etc. was 0.5-1.0 mm, according to this invention, it is 0.05-0.3 mm-thick thin light guide plate. High light utilization efficiency can be maintained.
As described above, according to the present invention, it is possible to use a large-sized light emitting diode element and an unprecedented thin light guide plate, which greatly contributes to the realization of a thin surface light emitting device that does not lower the light emission efficiency.

It is a figure explaining the Example of the surface mount type light emitting diode by this invention. It is a figure explaining the Example of the surface light-emitting device by this invention. It is sectional drawing explaining the conventional surface light-emitting device and the trouble of a prior art. It is a perspective view explaining the 2nd prior art. It is sectional drawing explaining the 2nd prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Surface light-emitting device 10 Light source 10 Surface mount type light emitting diode 22 Light emitting diode element 12 Board | substrate Lk4 Width Ld4 of the board | substrate with which the light emitting diode element is mounted Width 24 in the thickness direction of the light-incidence surface of a surface light-emitting device 24 Sealing a light emitting diode element Resin 16 Reflective layer 120 Light guide plate T1 Width in the thickness direction of the surface-mounted light emitting diode

Claims (7)

In the light source for surface emitting devices,
The light source is a surface mounted light emitting diode having a substrate,
The surface-mounted light-emitting diode has a light-emitting diode element mounted on the substrate as a light-emitting element,
The width of the surface of the substrate on which the light emitting diode element is mounted is larger than the width in the thickness direction of the light incident surface of the surface light emitting device,
The resin that seals the light emitting diode element on the substrate has a substantially triangular prism shape,
The surface mount light emitting diode has a reflective layer,
The surface-mounted light-emitting diode, wherein the light-emitting light of the light-emitting diode element is reflected from the reflective layer and then emitted from the surface-mounted light-emitting diode.   The light emitting diode element is mounted on one surface of the triangular prism-shaped sealing resin, the reflective layer is provided on the other surface, and the third surface is a light emitting surface. The surface mount type light emitting diode according to claim 1. In the light source for surface emitting devices,
The light source is a surface-mounted light-emitting diode having a substantially square columnar substrate,
The surface-mounted light-emitting diode has a light-emitting diode element mounted on the substrate as a light-emitting element,
The width of the surface of the substrate on which the light emitting diode element is mounted is larger than the width in the thickness direction of the light incident surface of the surface light emitting device,
The resin that seals the light emitting diode element on the substrate has a substantially triangular prism shape, and one surface of the three surfaces of the triangular prism is in contact with the light emitting diode element,
The other surface is provided with a reflective layer,
The third surface is the light emitting surface of the light emitting diode element,
Of the four surfaces of the substantially quadrangular prism-shaped substrate, two surfaces are substantially parallel to the reflective layer, and one of the two surfaces is on the same plane as the reflective layer. The other one of the two surfaces forms an angle substantially perpendicular to the two surfaces, and the surface of the four surfaces on which the light emitting diode element is mounted is inclined with respect to the reflective layer. A surface-mounted light emitting diode characterized by being set. In a surface light-emitting device having a light guide plate, a surface-mounted light-emitting diode is used as a light source, and light is emitted to a light-receiving device placed on the upper surface.
The surface-mounted light emitting diode is disposed on a side surface of the light guide plate,
The width of the surface of the substrate on which the light emitting diode element is mounted is larger than the thickness of the light guide plate,
By tilting the substrate surface on which the light emitting diode element is mounted with respect to the light guide plate, the thickness in the thickness direction of the surface mount type light emitting diode and the thickness of the light guide plate are made substantially equal. Surface emitting device.   5. The surface-emitting device according to claim 4, wherein the surface-mounted light-emitting diode according to claim 1 is used.   5. The surface light-emitting device according to claim 4, wherein the surface-mounted light-emitting diode according to claim 2 is used.   5. The surface light-emitting device according to claim 4, wherein the surface-mounted light-emitting diode according to claim 3 is used.

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