JPH0436588B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a light emitting diode that emits visible light or infrared rays, has a peripheral portion surrounded by a metal cap, and has a lens attached to the front side. .

(Prior Art) Generally, a light emitting diode having a structure including a metal cap and a lens is shown in FIG. 4. In the figure, 1 is a GaP-based or GaAsP-based light emitting device, and the light emitting device 1 is connected to a metal stem 2.
One lead 3 is integrally connected to the metal stem. The other lead 4 is made to look through the hole 2a provided in the metal stem 2 and is kept in an insulated state by a sealing glass 5.
A wire 6 is bonded between the end of the light emitting element 1 and the light emitting element 1 for electrical connection. A cylindrical metal cap 7 of an appropriate length is disposed so as to surround the circumferential surface of the metal stem 2, and a glass lens 8 is provided at the end of the metal cap to make parallel light beams. Has become a mounted structure. Incidentally, the light emission directivity characteristics of the GaP-based and GaAsP-based light emitting elements described above are as shown by the curve 9 in the graph of FIG.

In the conventional example having such a structure, the effective utilization range θ of the luminous flux in which the light emitted from the light emitting element 1 is irradiated to the outside through the lens 8 to become parallel rays is determined by the distance between the lens 8 and the light emitting element 1. The range is determined by the distance from the lens 8 and the diameter of the lens 8, and in reality, the range is about 60° as shown. In order to increase the front illuminance of the light emitting diode, the lens 8 and the light emitting element 1 are placed in contact with each other so that the light beam from the light emitting element 1 is made into a beam parallel to the optical axis X by the convex lens 8. They must be placed at appropriate intervals. Therefore, all of the luminous flux emitted from the light emitting element 1 cannot be directed toward the front, and is diffusely reflected inside the metal cap 7. In this way, when the light emitted from the light emitting diode is made parallel to the optical axis X using the convex lens 8, only the luminous flux within a range of 60° in the front direction can be used as described above.
As shown in FIG. 5, the utilization rate of the luminous flux is the worst.

(Problems to be Solved by the Invention) The present invention attempts to solve the problem of poor utilization of luminous flux from light emitting elements in conventional examples.

(Means for Solving the Problems) The present invention provides specific means for solving the problems described above, in which a light emitting element is mounted on a stem having one lead, and wire bonded to the other lead. In the light emitting diode in which a cylindrical cap having a lens is attached to the periphery of the stem, the lens has a generally bowl-shaped overall shape with a substantially flat front surface and a curved circumferential surface, and a concave cross section at the center of the rear surface. A light emitting diode, characterized in that a recessed portion is provided, the light emitting element is arranged so as to fit within the recessed portion, and the circumferential side surface is a curved surface that optically totally reflects the rays emitted from the light emitting element. Since the light emitting element is housed in the recessed part of the rear surface of the lens, most of the light emitted from the light emitting element is guided into the lens, and the light emitted from the light emitting element is emitted laterally on the circumferential side of the lens. rays are totally reflected and irradiated to the front side as parallel rays, most of the light emitted from the light emitting element is emitted to the front side, and there is no waste in the utilization rate of the luminous flux, and the brightness of the light emitting diode is reduced accordingly. will increase dramatically.

(Example) Next, the present invention will be explained in more detail with reference to illustrated examples. In order to facilitate understanding, parts that are the same as those in the prior art will be described with the same reference numerals.

In FIG. 1, reference numeral 1 indicates a GaP-based or GaAsP-based light emitting device. The light emitting device 1 is mounted on a metal stem 2, and one lead 3 is attached to the metal stem.
are connected together. The other lead 4 is arranged so that its end can be seen through the hole 2a provided in the metal stem 2, and the metal stem 2 is closed by a sealing glass 5.
A wire 6 is bonded between the ends of the leads 4 and the light emitting element 1 to electrically connect them.
The metal stem 2 is formed into a turret shape with a substantially flat upper surface, and a skirt portion 2b protrudes like a flange, and the sealing glass 5 is filled inside the turret shape to hold the other lead 4.

Reference numeral 7 denotes a metal cap having a cylindrical shape. The metal cap 7 has a lens 10 inside on the front side, and the rear end side is fitted or attached to the circumferential surface of the metal stem 2. A flange portion 7a is formed on the rear end side of the metal cap 7, and a hem portion 2a of the metal stem 2
Stabilize the fitted state by making contact with the

The lens 10 has a substantially flat front surface and a circumferential surface 1.
1 is formed into a curved surface, and a depressed portion 12 having a concave cross section is provided at the center of the rear surface. The bottom surface 1 of this depression
2a is raised in a parabolic curved shape toward the opening side, and the peripheral wall 12b of the recessed portion has a substantially shark-tooth-shaped cross section. As a means for attaching the lens 10 to the metal cap 7, for example, a flange portion 10a is provided around the front side, and the lens 10 is fitted through the flange portion. It is also possible to attach by other means.

The lens 10 having such a configuration has a metal cap 7.
When attaching the light emitting element 1 to the metal stem 2, the light emitting element 1 is placed in the recessed part 12 of the lens 10, and the light ray a emitted from the light emitting element 1 to the front side is directed to the bottom surface of the recessed part 12. The parabolic curved surface of 12a makes the ray parallel to the optical axis X,
The light ray b emitted from the light emitting element 1 to the side surface is first refracted when passing through the peripheral wall 12b, and the first refracted light ray is totally reflected by the curved surface of the peripheral side surface 11, and is emitted to the front side parallel to the optical axis X. is extracted as a ray of light. Therefore, the peripheral side surface 11 is formed into a paraboloid-shaped curved surface that optically totally reflects the radiation beam from the light emitting element 1. Furthermore, although the light rays emitted from the light emitting diode are parallel rays, if it is necessary to focus this ray at an arbitrary position, the front surface of the lens 10 may have a predetermined curvature.

(Effects of the Invention) As explained above, in the light emitting diode according to the present invention, the overall shape of the lens is formed into a bowl shape, and a recessed part with a concave cross section is provided at the center of the rear surface, so that the light emitting element is accommodated in the recessed part. The peripheral side of the lens has a curved surface that optically totally reflects the rays emitted from the light emitting element, so most of the rays emitted from the light emitting element are directed toward the front surface by the lens. The light is emitted in parallel with the rays, which has the excellent effect of having a high luminous flux utilization rate and greatly increasing brightness.

Further, when only parallel light beams are required, since the front surface of the lens is formed flat, the height of the entire light emitting diode can be lowered and the light emitting diode can be miniaturized, which is an excellent effect.

Furthermore, almost all of the luminous flux emitted from the light emitting element can be taken out to the front side of the light emitting diode.
If the same level of brightness as the conventional one is desired, the current consumption can be significantly reduced, which is also advantageous in terms of economy.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a light emitting diode according to the present invention, FIG. 2 is a front view of the same light emitting diode, FIG. 3 is a sectional view of a lens used in the same light emitting diode, and FIG. 4 is a conventional light emitting diode. A cross-sectional view of
FIG. 5 is a graph of the light emission directional characteristics of the light emitting element. 1... Light emitting element, 2... Metal stem, 3, 4...
... Lead, 5 ... Sealing glass, 6 ... Wire,
7...Metal cap, 10...Lens, 11...
Peripheral side, 12... depressed portion.

[Claims]

1 The LED element is mounted on a lead frame, stem, substrate, etc. and wire-connected, and the LED is molded with resin, has a through hole in the center, has a tapered outer periphery on the side, and is partially cut so that the light emitting surface is square. It consists of a substantially horn-shaped total reflection lens, and the LED is inserted into the through hole and combined,
A plurality of the cut rectangular side surfaces are arranged adjacent to each other to form a rectangular surface light source.
LED light source. 2. The LED light source according to item 1 above, characterized in that a plurality of total reflection lenses are integrally formed adjacent to each other.