JPS6125268Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to light emitting diodes.

As is well known, a light emitting diode emits light by passing a current through its diode chip. Usually, a drive circuit consisting of a transistor or the like is connected in series with the light emitting diode, and by turning on this transistor, a current flows through the diode chip. However, if leakage current flows through the transistor, this leakage current may flow through the diode chip, causing a slight glow. To prevent this, measures are taken such as using transistors with extremely low leakage current as transistors in the drive circuit or connecting a bypass resistor in parallel to the light emitting diode. However, in the former case, a high-performance transistor must be used, and in the latter case, a bypass resistor must be externally attached to the light emitting diode.
The connection work is time-consuming, and in either case there is a drawback that the cost increases or the work is complicated.

The purpose of this invention is to prevent the occurrence of faint light due to leakage current with a simple configuration.

This idea involves mixing a conductive material into the molding resin used for the envelope of the light emitting diode, thereby lowering the resin's original insulating performance and giving it the required resistance value. It is characterized by being configured to be connected in parallel to a diode chip.

Since the envelope made of molded resin is in direct contact with at least the frame that supports the diode chip and the frame to which the leads from the diode chip are connected, the resistance imparted by the molded resin exists between the two frames as distributed resistance. From an equivalent point of view, this means that a resistor is connected in parallel to the diode chip. By using this resistor as a bypass resistor, it is possible to prevent the occurrence of faint light due to leakage current.

An embodiment of this invention will be described with reference to the drawings. 1st
In the figure, reference numerals 1 and 2 are frames such as lead frames, one of which has a light emitting diode chip 3 mounted thereon, and lead wires 4 from this are connected to the other lead frame 2. Reference numeral 5 denotes an envelope, which in the illustrated example is molded with a translucent resin (for example, epoxy resin). That is, it is constructed by molding this resin around the tips of the lead frames 1 and 2, including the chips 3 and lead wires 4. However, according to this idea, a conductive material (for example, iron, aluminum, etc.) is mixed in advance into the resin constituting the envelope 5, and then this is molded. Usually, resin is an insulator, but by mixing a conductive material into it, it becomes conductive depending on the amount of the mixed material. The conductive material to be mixed is preferably a powder, but fine pieces,
It may be a linear body.

It goes without saying that even if a conductive material is mixed into the resin as described above, the resin will not become a low-resistance conductor, but will take on a resistance value depending on the amount mixed. Since this resin is in contact with at least the lead frames 1 and 2 inside the resin envelope 5, a resistor corresponding to the resistance value of the resin is formed between the lead frames 1 and 2. They will be connected equivalently in a manner similar to distributed resistance. Therefore, if this resin is made to have an appropriate resistance value, it will be equivalent to connecting a resistor in parallel to the chip 3. This resistor functions as a bypass resistor and can sufficiently suppress the slight light emission of the chip 3 due to leakage current.

Another embodiment shown in FIG. 2 is composed of a support 5A that supports the lead frames 1 and 2 as the surrounding air 5, and a molded part 5B made of a translucent resin. As described above, a resin molded with a conductive material mixed therein is used. Even in this case, the resistance of the support 5A is equivalently connected between the lead frames 1 and 2, and the chip 3 is prevented from emitting light. In addition, when using the support body 5A as described above, it is also possible to use a normal case (for example, made of metal) in place of the mold part 5B, and a case with a hemispherical glass lens provided on the head. good.

As detailed above, according to this invention, when a bypass resistor is connected in parallel to a light emitting diode to prevent faint light emission caused by leakage current flowing in a drive circuit, for example, the resin mold that constitutes the envelope By mixing a conductive material into the part, the envelope itself in contact with the frame has a resistance commensurate with the bypass resistance, so there is no need to attach a conventional good resistor externally, which greatly improves work efficiency. In addition, there is no need to prepare a resistor for this purpose, and there is also no need to use a high-performance drive circuit with extremely low leakage current.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of this invention, Figure 2 is a sectional view showing an embodiment of this invention.
The figure is a sectional view showing another embodiment of this invention. 1, 2...Frame, 3...Light emitting diode chip, 5...Envelope.

Claims (1)

[Scope of utility model registration request] In a light emitting diode in which a light emitting diode chip is installed in one of a pair of frames, the chip is connected to the other frame, and is surrounded by an envelope, at least the portion of the envelope that is in contact with both frames. A light emitting diode made of a molded resin mixed with a conductive material to provide a resistance value equivalent to a parallel resistance that suppresses slight light emission.