JPH0427175A - Multicolor light emitting diode - Google Patents

Abstract

PURPOSE:To obtain a multicolor light emitting diode having light distribution characteristic to be easily observed remotely by forming an emitting surface in a columnar state, and disposing a light emitting element on a straight line perpendicular to a line parallel to the emitting surface to perpendicularly cross the central axis of a recess reflecting surface. CONSTITUTION:A z-axis is in a central axis direction of a recess reflecting surface 12, an x-axis is in a direction perpendicular to the z-axis in a plane including the edge of surface 12, and a y-axis in a direction perpendicular to the z-axis and the x-axis in a plane including the edge of the surface 12. Light emitting elements 2a, 2b are disposed at an interval of 0.6mm on the y-axis symmetrical to the z-axis, the surface 12 is formed at the side opposed to the emitting surfaces of the elements 2a, 2b, and emitting surfaces 14 are formed on the back surfaces of the elements 2a, 2b. The surface 12 is formed in an elliptical surface shape having a long axis at the x-axis direction and a short axis at the y-axis direction in the section of a plane perpendicular to the z-axis. The surface 14 is formed parallel to the x-axis.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improving the light distribution characteristics of multicolor light emitting diodes used, for example, in color displays.

[Conventional technology]

Figure 6 is a schematic front view of a conventional multicolor light emitting diode;
The figure is a schematic cross-sectional view taken along the line C-C of the multicolor light emitting diode.
FIG. 8 is a schematic cross-sectional view taken along the line D--D of the multicolor light emitting diode. The multicolor light emitting diodes shown in FIGS. 6 to 8 include a red light emitting element 52a and a yellow green light emitting element 5.
2b, lead frame 54a, 54b, 56, wire 5
8. Light-transmissive material 60, concave reflective surface 62 and emissive surface 6
Consists of 4. Note that the z-axis is the central axis direction of the concave reflective surface 62, and the X-axis is the z-axis in the plane including the edge of the concave reflective surface 62.
The direction perpendicular to the axis (horizontal direction), the y-axis is the concave reflective surface 62
2 axes in the plane including the edge of and the direction perpendicular to the X axis (
vertical direction).

The light-emitting elements 52a and 52b are arranged at 0.6-inch intervals on the y-axis symmetrically with respect to the z-axis.

The concave reflective surface 62 is formed so that a cut surface taken by a plane perpendicular to the z-axis has an ellipsoidal shape having a long axis in the x-axis direction and a short axis in the y-axis direction. Further, the major axis of the ellipse at the edge of the concave reflective surface 62 is 5° On.

In the multicolor light emitting diode configured in this way, the light emitted by each light emitting element 52a, 52b is reflected by the concave reflecting surface 62 and then radiated to the outside from the emitting surface 64, so that the light emitted by each light emitting element is Almost the entire luminous flux can be emitted forward.

By the way, when the light emitting elements are arranged offset from the two axes as in the multicolor light emitting diodes shown in Figs. 6 to 8, the radiation angle becomes larger than when the light emitting elements are arranged on the two axes. . When such a multicolor light emitting diode is installed in a high place and used for a color display or the like that can be viewed from a distance, the light emitting directions of the light emitting elements 52a and 52b are greatly different, so that one color of light cannot be visually recognized. If it is made easier, it becomes difficult to see the light of the other color. For this reason, in conventional color displays, in order to average the light of both colors and make it easier to see, a red light emitting element 52a is placed below a yellowish green light emitting element 52b, as shown in the light emitting diode shown in FIG. A multicolor light emitting diode placed on the side and a red light emitting element 5 with the multicolor light emitting diode shown in FIG. 8 turned upside down.
Multicolor light emitting diodes 2a are disposed above yellow-green light emitting elements 52b and are alternately arranged in a grid pattern.

[LI problem to be solved by the invention] However, in the conventional multicolor light emitting diode, since the light emitting elements are arranged offset from the two axes, the light emission from each light emitting element 52a, 52b is The directions are very different. FIG. 9 is a diagram showing the light distribution characteristics of light emitted by the light emitting elements disposed on the lower side in the conventional multicolor light emitting diode shown in FIGS. 6 to 8. As shown in FIG. 9, the radiation intensity of the light emitted by the light emitting element 52a has a peak at a radiation angle of approximately 18 degrees in the y-axis direction (vertical direction).
Has wide light distribution characteristics in the axial direction. On the other hand, when a multicolor light emitting diode is installed at a high place and used as a light source for a color display that is visible from a distance, a wide viewing angle in the vertical direction is not required, and conventional multicolor light emitting diodes Most of the emitted light in the vertical direction is wasted.

In addition, in color displays using conventional multicolor light emitting diodes, the vertical radiation angle is large, so the radiation intensity within the viewing angle range cannot be sufficiently increased, making it difficult to see. .

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a multicolor light emitting diode having light distribution characteristics that are easily visible from a distance.

[Means to solve the problem]

To achieve the above object, the present invention includes a plurality of light emitting elements emitting light of different colors, a lead portion for supplying power to the light emitting elements, and a concave reflective surface provided opposite to the light emitting surface of the light emitting element. and a radiation surface that emits light emitted by the light emitting element and reflected by the concave reflecting surface to the outside, wherein the radiation surface is formed in a convex cylindrical shape, and the light emitting element It is characterized in that it is arranged on a straight line that is perpendicular to a straight line parallel to the convex cylindrical radiation surface and perpendicular to the central axis of the concave reflective surface.

Further, the side surface substantially perpendicular to the radiation surface formed in the convex column shape may be formed as a smooth flat surface.

[Effect]

According to the above-described configuration, the present invention provides a light emitting element that is arranged offset from the central axis of the concave reflective surface in order to arrange a plurality of light emitting elements, for example, in a direction perpendicular to a straight line parallel to the emitting surface (hereinafter referred to as the y axis). It is called direction.

) The light emitted by the light-emitting elements that are disposed offset from each other and reflected by the concave reflective surface has a reflection angle shift in the y-axis direction with respect to the light emitted from the central axis of the concave reflective surface, and the central axis The light reaches a radiation surface that has a different slope than the light emitted from it. on the other hand,
Since the radiation surface is formed in the shape of a convex column, it is possible to reduce the deviation in the light distribution characteristics that is spread in the y-axis direction by the concave reflection surface.

In addition, by forming the side surface substantially perpendicular to the radiation surface formed in the convex columnar surface as a smooth flat surface, the light incident on the side surface can be totally reflected. The radiation angle in the direction parallel to the radiation plane can be widened.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is a schematic front view of a multicolor light emitting diode according to an embodiment of the present invention, and FIG. 2 is an A-A diagram of the multicolor light emitting diode.
A schematic cross-sectional view in the direction of arrows, Figure 3 is B of the multicolor light emitting diode.
-B is a schematic sectional view taken along the arrow.

The multicolor light emitting diode shown in FIGS. 1 to 3 includes a red light emitting element 2a, a yellow green light emitting element 2b, lead frames 4a, 4b, 6, wires 8, and a light-transmitting material 10. , a concave reflective surface 12, a radiation surface 14, and side surfaces 16a and 16b. Note that the z-axis is the direction of the central axis of the concave reflective surface 12, the X-axis is the horizontal direction perpendicular to the Z-axis in the plane that includes the edge of the concave reflective surface 12, and the y-axis is the direction This is the direction perpendicular to the two axes and the X axis in the plane containing the image.

The light emitting elements 2a and 2b are arranged at 0.6 mm intervals on the y-axis symmetrically with respect to the two axes, and are mounted on lead frames 4a and 4b, respectively.

Further, the light emitting element 2 a and the lead frame 4 b and the light emitting element 2 b and the lead frame 6 are electrically connected by wires 8 . The light emitting elements 2a, 2b, the tips of the lead frames 4a, 4b, 6, and the wire 8 are integrally sealed with a light-transmitting material 10.

A concave reflective surface 12 is formed on the side opposite to the light emitting surface of the light emitting elements 2a, 2b, and a radiation surface 14 is formed on the back side of the light emitting elements 2a, 2b. The concave reflective surface 12 is made by mirror-finishing one surface of the light-transmitting material 10 by plating, metal vapor deposition, etc., and prevents short circuits between the three lead frames 4a, 4b, and 6 during mirror-finishing. To prevent this, the lead frames 4a, 4b, 6 must be provided with a vA edge.

The concave reflective surface 12 is formed so that a cut surface taken by a plane perpendicular to the z-axis has an ellipsoidal shape having a long axis in the x-axis direction and a short axis in the y-axis direction. Further, the major axis of the ellipse at the edge of the concave reflective surface 12 is 5.0 mm. On the other hand, the radiation surface 14 is a convex cylindrical surface formed in a hyperbolic cylindrical shape on the other surface of the light-transmitting material 10. This convex cylindrical radiation surface 14 is formed parallel to the X axis.

Further, the side surfaces 16a, 16a are smooth flat surfaces substantially perpendicular to the X axis, and the side surfaces 16b, 16b are flat surfaces perpendicular to the y axis. Note that the concave reflective surface 12 and the side surface 16b are designed so that the light reflected by the concave reflective surface 12 does not reach the side surface 16b.

FIG. 4 is a diagram showing the light distribution characteristics of light emitted by the light emitting elements disposed on the lower side of the multicolor light emitting diode according to this embodiment shown in FIGS. 1 to 3. FIG.

The radiation angle θ8 in the X-axis direction is the angle in the X-axis direction with respect to the z-axis, and the radiation angle θ8 in the y-axis direction is the angle in the y-axis direction with respect to the two axes. The light distribution characteristic diagram of the light emitted by the light emitting element disposed on the upper side is a diagram symmetrical with respect to the radiation angle θ in the X-axis direction (horizontal direction) in FIG. 4.

In the multicolor light emitting diode configured as described above, the light emitted by the light emitting element 2a is reflected at the concave reflective surface 12, but as shown in FIG. For example, in the upper half of the concave reflective surface 12, compared to the case where the light emitting element is disposed on the central axis of the concave reflective surface 12,
A shift in the reflection angle occurs that spreads upward in the front direction. on the other hand,
On the radiation surface 14, the light that spreads upward in the front reaches the position of the radiation surface with a different inclination angle, and compared to the light emitted from on the central axis of the concave reflection surface 12,
It is refracted significantly downward and radiated to the outside. For this reason,
When the dimensions of the concave reflective surface 12 and the arrangement spacing of the light emitting elements are the same as those of the conventional one, the light emitting elements 2a are arranged offset from the two axes by making the radiation surface 14 into a convex columnar shape. The light distribution characteristics of the multicolor light emitting diode of this embodiment are as shown in FIG. 4 in the y-axis direction (vertical direction).
The radiation intensity has a peak when the radiation angle θ is approximately 8 degrees. Therefore, it is possible to reduce the angle between the peak of the radiation intensity of the red light-emitting element 2a and the peak of the radiation intensity of the yellow-green light-emitting element 2b. Furthermore, the concave reflective surface 12 and the convex cylindrical radiation surface 14 reduce the deviation angle caused by the arrangement of the light emitting elements offset from the central axis, and improve the radiation intensity within the visible angle range. be able to.

As a result, by using the multicolor light emitting diode in this example as a light source for color displays, etc.,
Since the angle between the peaks of the radiation intensity from the light emitting elements of each color can be made small and the radiation intensity can be increased, a display that can be easily recognized even from a distance can be obtained.

FIG. 5 is a diagram illustrating the optical path of light emitted by the light emitting element in the multicolor light emitting diode of the present invention.

In FIG. 5, 14. 14 is a convex cylindrical radiation surface formed with a small distance from the concave reflecting surface 12;
z is a convex cylindrical radiation surface formed with a large distance from the concave reflective surface 12; Incidentally, the radiation surface 141 and the radiation surface 14□ are formed in the same shape. Of the light emitted from the light emitting element 2a, we will consider the light that is reflected at the point P on the concave reflective surface 12. . First, when the radiation surface 141 is formed with a small distance from the concave reflecting surface 12, the light reflected at the point P is transmitted to the radiation surface 14. Point A above (the inclination angle of the radiation surface at this point, i.e.
The angle between the tangent plane of the radiation surface and the y-axis at this point is α
It is 1. ), and the angle β1 with respect to the direction of incidence is
refracts only downward. On the other hand, when the radiation surface 14□ is formed by increasing the distance between it and the concave reflecting surface 12,
The light reflected at point P reaches point B on the radiation surface I4□. The inclination angle α of the radiation surface 14g at point B is the angle α1
Therefore, at point B, the reflected light is largely refracted downward at an angle β2 larger than the angle β1 with respect to the incident direction, and is emitted to the outside. Therefore, in order to greatly reduce the deviation of the light reflection angle caused by arranging the light emitting element off the central axis of the concave reflective surface, it is necessary to The distance between the radiation surface and the radiation surface may be increased. For this reason, in the light emitting diode of this embodiment, as shown in FIG. 3, the distance between the concave reflecting surface and the convex cylindrical emitting surface is made long.

In addition, if you want to have wider light distribution characteristics in the horizontal direction (X-axis direction), the concave reflective surface usually has an elliptical cross section taken by a plane perpendicular to the two axes.
It is necessary to further increase the major axis in the axial direction and further decrease the minor axis in the y-axis direction. In this case, in this embodiment, since the side surface 16a is a smooth flat surface, the reflected light reaching the side surface 16a is totally reflected on the side surface 16a and then radiated to the outside from the radiation surface 14. Therefore, it is possible to have a wide light distribution characteristic in the horizontal direction without increasing the length of the radiation surface in the straight line direction (X-axis direction) parallel to the convex cylindrical radiation surface.

In the above embodiment, the case where the convex cylindrical radiation surface is formed into a hyperboloid shape is explained, but the present invention is not limited to this, and the convex cylindrical radiation surface is formed into a convex shape. It may be formed into any shape as long as it is.

Further, in the above embodiment, a case has been described in which two light emitting elements emitting light of different colors are arranged on the y-axis, but the present invention is not limited to this. Three or more light emitting elements may be arranged.

Further, in the above embodiment, the case where the long axis of the ellipse at the edge of the concave reflective surface and the straight line parallel to the convex cylindrical radiation surface are formed in parallel, but the present invention is not limited to this. Instead, the short axis of the ellipse and a straight line parallel to the radiation surface may be parallel to each other.

〔Effect of the invention〕

As explained above, according to the present invention, since the radiation surface is formed into a convex columnar shape, the reflection on the concave reflection surface due to the fact that the light emitting element is arranged offset from the center axis of the concave reflection surface. Since angular deviations can be reduced on the radiation surface, compared to conventional ones, for example, deviations in the horizontal light distribution characteristics of light-emitting elements that are disposed horizontally are reduced, and the radiation intensity within the visible angle range can be reduced. It is possible to provide a multicolor light emitting diode that has practical light distribution characteristics that can increase the size of the LED and make it easy to see even from a distance.

[Brief explanation of drawings]

FIG. 1 is a schematic front view of a multicolor light emitting diode according to an embodiment of the present invention, and FIG. 2 is an A-A diagram of the multicolor light emitting diode.
A schematic cross-sectional view in the direction of arrows, Figure 3 is B of the multicolor light emitting diode.
-B schematic cross-sectional view in the direction of arrow B, FIG. 4 is a light distribution characteristic diagram of light emitted by the light emitting element disposed on the lower side of the multicolor light emitting diode, and FIG. 5 is a diagram of the light emitting element in the multicolor light emitting diode of the present invention. 6 is a schematic front view of a conventional multicolor light emitting diode, FIG. 7 is a schematic sectional view taken along the line C-C of the multicolor light emitting diode, and FIG. 8 is a diagram illustrating the multicolor light emitting diode. FIG. 9, which is a schematic cross-sectional view taken along line D-D of the light emitting diode, is a light distribution characteristic diagram of light emitted by a light emitting element disposed on the lower side of the multicolor light emitting diode. 2a... Light-emitting element that emits red light, 2b... Light-emitting element that emits yellow-green light, 4a, 4b, 5... Lead frame, 899. Wire, 10... Light-transmitting material, 12... Concave reflective surface, 14... Radiation surface, 16a, 16b... Side surface. Applicant Iwasaki Electric Co., Ltd. Agent Patent attorney Han 1) Masa younger brother 1] B Figure 3 Figure 6 Figure 7 Figure 8

Claims (2)

[Claims] (1) A plurality of light emitting elements emitting light of different colors, a lead portion for supplying power to the light emitting elements, a concave reflective surface provided opposite to the light emitting surface of the light emitting element, and a plurality of light emitting elements emitting light from the light emitting element. In a multicolor light emitting diode having a radiation surface that radiates light reflected by a concave reflective surface to the outside, the radiation surface is formed in a convex cylindrical shape, and the light emitting element is attached to the convex cylindrical radiation surface. A multicolor light emitting diode, characterized in that it is arranged on a straight line that is perpendicular to parallel straight lines and perpendicular to the central axis of the concave reflective surface. (2) The multicolor light emitting diode according to claim 1, wherein a side surface substantially perpendicular to the radiation surface formed in the shape of a convex column is formed as a smooth flat surface.