JP3209161B2 - Semiconductor light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device in which an LED light emitting element is mounted on a mount formed on a lead frame, a printed circuit board, or another molded product, and in particular, to adjust the angle of a reflection surface formed on the mount. Accordingly, the present invention relates to a light emitting device capable of improving the light distribution from the light emitting device and optimizing the light emitting display.

[0002]

2. Description of the Related Art Conventionally, an LED light-emitting element having p-side and n-side electrodes formed by laminating a semiconductor thin film layer on a crystal substrate to form a pn junction semiconductor has been widely used for a light emitting display panel. Have been. The basic configuration of this LED light-emitting element is that it is mounted on a mount formed in advance on a lead frame provided as a member for electrical conduction, for example, and connected to the lead frame by wire bonding.

FIG. 5 is a schematic view showing a conventional example of a structure for mounting a light emitting element on such a lead frame mount.

In the example shown in the figure, a light emitting element 51 can be used as a blue LED in which a semiconductor film of a gallium nitride-based compound is laminated. A light emitting element 51 is mounted on a mount 52 a having an insulating substrate 51 a formed on the upper end of a lead frame 52. And the p-side pole 51b and the n-side pole 51c respectively formed on the upper end of the light emitting element 51 and bonded to the lead frame 52 and the other lead frame 55 paired with the lead frame 52 by wires 54a and 54b. Connected to Then, the mount 52 including the light emitting element 51 is mounted.
The entire area around a is sealed with an epoxy resin 56.

In an LED lamp including such a light emitting element 51, a pn junction region of a gallium nitride compound semiconductor film of the light emitting element 51 is used as a light emitting layer, and a p-type layer occupying a region including a p-side electrode 51b is formed. Light emission upward can be obtained using the upper surface as a light extraction surface. When the substrate 51a is made of transparent sapphire, light traveling from the light emitting layer toward the mount 52a is reflected from the mount 52a, and merges with the light emitted from the light extraction surface including the reflected light.

On the other hand, the three primary color LEs having the light emitting elements 51 are provided.
A light-emitting display panel in which a large number of D lamps are arranged and arranged,
Each of the LED lamps serves as a pixel so that various images can be displayed and a color can be displayed. The light-emitting display panels range from relatively small ones to large ones for outdoor use, and their installation locations are various.

For example, when a light-emitting display panel is provided at a high position along an exterior wall of a building, information provided by display is generally intended for a driver such as a pedestrian on a sidewalk or a running car. It is. Therefore, a pedestrian or driver often looks up when looking at the display panel. Even in the case of the LED light emitting device shown in FIG. 5, the pedestrian or the driver rotates the light emitting device 90 ° clockwise in FIG. When the directions are arranged on the display panel, the optical path is greatly shifted to the observer.

Therefore, as shown in FIG.
If the setting of the optical path by the mount 52a for reflecting light is set obliquely downward, light distribution can be provided to a person who looks up at the light emitting display panel. This allows
The display is brighter and more vivid for the viewer.

[0009]

In order to make the optical axis of the light from the light emitting element 51 downward, for example, as shown in FIG. 6A, it is connected to a printed board 57 provided on the entire surface of the light emitting display panel. This can be handled by bending the lead frames 52 and 55 downward. Also, the lead frames 52, 5
In order to suppress an error in posture due to bending deformation of 5, a part of the printed circuit board 57 can be inclined obliquely in a tongue shape so that the direction of the light emitting element 51 is adjusted to the ground side as shown in FIG. .

However, when the lead frames 52 and 55 and the printed circuit board 57 are bent, the bending angles are accompanied by manufacturing errors, so that it is inevitable that variations occur, and management during the manufacturing process must be strict. Must. If the accuracy of the bending angle is poor, the light distribution direction of the light emitting element 51 corresponding to each pixel also varies, which greatly affects the sharpness of the image display from the light emitting display panel.

As described above, if the light-emitting element 51 can be incorporated into the light-emitting display panel in a proper posture so as to face the observer, the form of the light-emitting display can be maintained satisfactorily. It is not possible, and it is easy to be complicated in terms of quality control.

The problem to be solved in the present invention is to provide a light emitting device which can always set a constant light distribution from a light emitting element and can obtain a good light emitting display panel without being affected by manufacturing errors. It is in.

[0013]

According to the present invention, there is provided a light emitting device in which a pn junction semiconductor layer is laminated on a crystal substrate, and a mounting conductive member for mounting the light emitting device and electrically conducting the light emitting device. A semiconductor light emitting device in which a mounting conductive member is formed as a concave body having a depth such that the light extraction surface of the light emitting element is buried and a light reflecting surface is formed on the inner surface thereof; A reflecting surface that reflects emitted light other than the main optical axis direction of the light emitting element in a direction having a certain range of incident crossing angles with respect to a plane including the main optical axis from the main light extraction surface where the light emission luminance of the element is the highest. With structure, anti-mount
The projecting surface structure consists of two areas facing each other with the light emitting element
The main reflection surface and the sub-reflection surface
The intersection angle between the sub-reflection surface and the main optical axis of each light-emitting element
Are relatively small and large, and the
Of the diffused light and the reflected light of the light emitted from other than the main light extraction surface
Light intensity distribution is larger on the sub-reflection surface side than on the main reflection surface side
It is characterized by being biased as follows.

With such a configuration, for example, when a lead frame is used as the mounting conductive member, when a mount is formed at the tip of the lead frame and the light emitting element is mounted thereon, Not only the light from the main light extraction surface, which has the highest light emission brightness,
Light from other light extraction surfaces can also be emitted with directivity. In this case, in the case of a light emitting element of a transparent crystal substrate whose main light extraction surface coincides with the light emitting direction and the crystal substrate is in a position facing the mounting surface of the mount, light leaking from the transparent crystal substrate is emitted from the mount. It can be collected as reflected light.

In the present invention, the mounting conductive member for mounting and electrically connecting the light emitting element is a lead frame as described in the embodiment of the present invention. Various types of molded products may be arranged separately above the substrate.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pn
A light-emitting element having a stacked semiconductor layer, and a mounting conductive member for mounting the light-emitting element and electrically connecting the light-emitting element, the mounting conductive member having a depth such that the light extraction surface of the light-emitting element is buried. A semiconductor light emitting device in which a mount having a concave body and an inner surface having a light reflecting surface is formed, and the mount includes a main light axis from a main light extraction surface having the highest light emission luminance of the light emitting element. A reflective surface structure for reflecting emitted light in directions other than the main optical axis direction of the light emitting element with a certain range of incident crossing angles, and a mount reflective surface structure.
Is divided into two areas facing each other with the light emitting element
Main reflection surface and sub-reflection surface.
The intersection angle between the surface and the main optical axis of each light emitting element
And the relationship between small and large, diffused light from the main light extraction surface and
Light intensity distribution of reflected light of emitted light from other than this main light extraction surface
However, it is biased so that the sub-reflection surface side is larger than the main reflection surface side.
The mount itself has the function of efficiently extracting light emitted from the side and back surfaces of the light-emitting element, if the light-emitting element has a transparent crystal substrate and light from the main light extraction surface. .

Further , according to the present invention, there is an effect that the reflected light from the main reflecting surface can be added as a light distribution component of its directing destination.

Hereinafter, specific examples of the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a main part of an LED lamp provided as a light emitting element with an LED chip formed by a gallium nitride-based compound semiconductor film according to an embodiment of the present invention. FIG. 2 is a plan view of FIG. 3
FIG. 2 is a longitudinal sectional view taken along line AA of FIG. 1.

In the figure, a pair of lead frames 1 and 2 whose upper ends are sealed with epoxy resin are provided.
One lead frame 1 is used as the mounting conductive member in the present embodiment. At the upper end of one of the lead frames 1, a mount 3 for mounting the light emitting element 4 is formed in a substantially mortar-like concave shape, and the entire inner peripheral surface is mirror-like. In the light emitting element 4, a crystal substrate 4a using transparent sapphire is provided on a lower end side, and a p-side electrode 4b and an n-side electrode 4c are formed on an upper end side, and these are respectively connected to lead frames 1 and 2 by wires 5a and 5b. Wire bonding.

The light emitting element 4 has a p-type layer including the p-side electrode 4b on the upper surface thereof as a main light extraction surface having the highest light emission luminance, and includes a main optical axis in a light emission optical path from the main light extraction surface. And a crystal substrate 4a located below the light emitting layer.
Also emits light to the side and downward.

As shown in FIG. 2, the mount 3 is formed in a mortar shape such that the light emitting element 4 has a substantially square planar shape and is eccentrically arranged. Is set as a sub-reflection surface 3a having a gradient of about 40 °, and a region opposed thereto is set as a main reflection surface 3b having a gradient of about 60 °. The gradient between the sub-reflection surface 3a and the main reflection surface 3b is 50, as shown in FIG.
The second sub-reflection surface 3a-1 is used to provide directivity in the width direction of the optical path of about °.

On each of the sub-reflection surface 3a and the main reflection surface 3b at a position facing the sub-reflection surface 3a, a holding seat 3c having a substantially trapezoidal planar shape for mounting the light emitting element 4 is formed. A cavity 3d is provided at the lower part to be depressed downward to provide a gap between the light emitting element 4 and the bottom surface. The bottom of the cavity 3d coincides with the bottom of the mortar-shaped mount 3, and between the holding seats 3c, a reflection block 3e having an isosceles trapezoidal vertical cross-sectional shape as shown in FIG. 1 is formed. The two surfaces of the block 3e are light receiving / reflecting surfaces 3f and 3g for light traveling downward from the light emitting element 4. The block 3e may be any as long as it can form a trapezoidal reflecting surface as shown in the figure, and may be any as long as the outer shell has a truncated cone or truncated pyramid. As shown in FIG. 1, the light emitting element 4 has both sides mounted on the holding seat 3c and is adhered to the holding seat 3c by the transparent paste 6.

In the above configuration, when the light-emitting element 4 is energized, light from the light-emitting layer in the pn junction region is emitted from the main light extraction surface on the upper surface of the p-type layer as described above. At the same time, it leaks downward and laterally from the crystal substrate 4a using transparent sapphire.

At this time, since the main light extraction surface of the light emitting element 4 enters the mount 3 deep enough, the amount of diffusion of light on the optical axis from the light extraction surface is reduced by the sub-reflection surface 3a and the second reflection surface. Are reflected in the light emitting direction by the sub-reflection surface 3a-1 and the main reflection surface 3b.

Light emitted from the light emitting element 4 to the side passes through the transparent paste 6 and passes through the sub-reflection surface 3 of the mount 3.
a, the second sub-reflection surface 3a-1 and the main reflection surface 3b, and these sub-reflection surface 3a, second sub-reflection surface 3a-1,
The light is reflected from the main reflection surface 3b in substantially the same direction as the light emission direction from the main light extraction surface of the light emitting element 4.

Further, light traveling downward from the crystal substrate 4a is:
After reaching the light receiving / reflecting surfaces 3f and 3g of the reflecting block 3e located just below the light emitting element 4 and being reflected, the light path is changed to the pair of second sub-reflecting surfaces 3a-1 facing these. . Then, similarly to the light from the side, the light is reflected by the second sub-reflection surface 3a-1 and travels in substantially the same direction as the light emission direction from the light extraction surface of the light emitting element 4.

As described above, light leaking laterally and downward from the crystal substrate 4a, including light from the light extraction surface of the light emitting element 4, is transmitted to the sub-reflection surface 3a and the second sub-reflection surface 3a of the mount 3.
-1 and all light is reflected from the main reflection surface 3b. Therefore, for example, in the case where light leaked from the crystal substrate 4a is reflected and then emitted from the main light extraction surface after being incident on the crystal substrate 4a, the amount of light finally emitted due to the relationship of light transmittance and the like. Is attenuated, but light directly reflected from the sub-reflection surface 3a, the second sub-reflection surface 3a-1, and the main reflection surface 3b is obtained. Thus, in addition to the light emission from the light extraction surface, light emitted from the transparent crystal substrate 4a can be added, and the luminous efficiency can be greatly improved.

FIG. 4 is a sectional view of a main part showing the attitude of the light emitting device when incorporated in a light emitting display panel arranged at a high position along the exterior of a building or the like.
However, it is a matter of course that in an actual light emitting display panel, many light emitting devices are uniformly arranged in the same plane.

As can be seen from FIG. 4, the lead frame 1 connecting the light emitting device to the printed circuit board (not shown) of the light emitting display panel is arranged so that the sub-reflection surface 3a of the mount 3 is on the lower side. When the light emitting display panel is viewed from the light emitting surface side, it appears as shown in FIG.

In such an arrangement of the light emitting devices, the main reflection surface 3b covers the light emitting element 4 above. For this reason, the main light extraction surface of the light emitting element 4 itself remains horizontal in the drawing, but since the main light extraction surface is deeply penetrated into the mount 3, a part of the light emission from this main light extraction surface. Is reflected by the main reflection surface 3b. Further, the light that leaks to the side and back of the crystal substrate 4a interferes with the sub-reflection surface 3a and the second sub-reflection surface 3a-1.

At this time, the light reflected on the main reflection surface 3b becomes an optical path crossing obliquely downward from the main optical axis of the optical path from the main light extraction surface of the light emitting element 4. And the sub-reflection surface 3a
Is opened downward so as not to block the reflected light from the main reflecting surface 3b, so that almost all of the reflected light from the main reflecting surface 3b is emitted obliquely downward. Therefore,
As for the light quantity distribution of the reflected light on the front side of the mount 3, as shown by the dashed line in FIG.

Here, when the amount of light reflected from the main reflection surface 3b is added to the amount of light emitted from the main light extraction surface of the light emitting element 4, the emission luminance is improved by about 10% as compared with the conventional structure. It is possible. Therefore, even in the arrangement shown in FIG. 4 in which the light from the main light extraction surface of the light emitting element 4 is directed in the horizontal direction, the light reflected from the main reflection surface 3b is added so that the observer on the ground side can see. At this time, the light emission luminance is increased, and a clear image can be perceived.

[0033]

According to the present invention, the directivity is given to each of the light from the main light extraction surface of the light emitting element and the light emitted from the transparent crystal substrate by the mount itself provided on the lead frame or the printed circuit board. If the accuracy of assembling the lead frame into the light-emitting display panel is made high, a good light-emitting image can be obtained without any deviation or variation in the light-emitting direction after assembly.

Further, since it is possible to add a light reflected from the main reflection surface as a light distribution component of the oriented destination, only to have these main reflection surface and the sub reflection surface mount provided on a lead frame or a printed circuit board or the like With this simple configuration, it is possible to reproduce a highly accurate luminescent image.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a light emitting device using a gallium nitride based compound semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a longitudinal sectional view taken along line AA of FIG. 1;

FIG. 4 is a schematic diagram showing an arrangement posture of a lead frame on a light emitting display panel and a diagonally downward direction of light reflected by a main reflection surface.

FIG. 5 is a schematic view showing an example of a conventional LED lamp.

6A and 6B show a conventional example in which an LED lamp is inclined obliquely downward, in which FIG. 6A is a view showing a bent lead frame, and FIG. 6B is a schematic view showing a bent printed circuit board.

[Explanation of symbols]

 Reference Signs List 1 lead frame (mounting conductive member) 2 lead frame 3 mount 3a sub-reflection surface 3a-1 second sub-reflection surface 3b main reflection surface 3c holding seat 3d cavity 3e reflection block 3f, 3g light reception reflection surface 4 light emitting element 4a crystal substrate 4b p-side electrode 4c n-side electrode 5a, 5b wire 6 paste

Continuation of the front page (72) Inventor Kazuya Yamaguchi 1-1, Sachimachi, Takatsuki-shi, Osaka Inside Matsushita Electronics Corporation (56) References JP-A-9-64421 (JP, A) Shokai Sho 62- 196365 (JP, U) JP-A-3-67459 (JP, U) JP-A 6-60157 (JP, U) JP-A 5-8961 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01L 33/00

Claims (1)

(57) [Claims] 1. A light emitting device comprising: a pn junction semiconductor layer laminated on a crystal substrate; and a mounting conductive member for mounting the light emitting device and electrically conducting the light emitting device.
A semiconductor light emitting device in which a light-emitting surface of a light-emitting element is formed in a concave shape having a depth such that the light-extraction surface is buried, and a mount having an inner surface as a light-reflecting surface is formed. It has a reflective surface structure that reflects emitted light other than the main optical axis direction of the light-emitting element in a direction with a certain range of incident crossing angles with respect to a plane including the main optical axis from the main light extraction surface , and the reflection of the mount. The surface structure has a light emitting element between
The main reflection surface and the sub-reaction surface divided into two areas facing each other
Light-emitting surface and the main reflection surface and the sub-reflection surface
The intersection angle of the element with the main optical axis is relatively small and large.
The diffused light from the main light extraction surface and
The light intensity distribution of the reflected light of the emitted light from the outside is
Also, the semiconductor light emitting device is biased so that the side of the sub-reflection surface becomes large .