JPS6244832B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric device, and particularly to a light emitting device and a light receiving device used in an optical transmission system.

Optical transmission systems have excellent characteristics such as low noise and wide bandwidth, so they have come to be widely used for wiring not only communications and CATV but also automobiles, audio, and other consumer equipment.

An example of this will be explained with reference to FIG. 1. The circuit board 5 in the transmitting device includes a waveform shaper current amplifier (hereinafter referred to as peripheral circuit) that faithfully converts an electrical signal into an optical signal, and a circuit board 5 for electrical-to-optical conversion. Light-emitting elements such as LED elements and LD elements are each wired via a circuit board, or the light-emitting device 1 incorporating a light-emitting element and a peripheral circuit IC element or a peripheral circuit IC element including a light-emitting element is mounted on a lead frame. 2 to a predetermined wiring 4 with solder 3. In addition, on the circuit board 10 in the receiving side equipment, a light receiving element such as a PD element or an APD element, which faithfully converts an optical signal into an electric signal, and peripheral circuits are respectively wired via the circuit board, or the light receiving element and peripheral circuits are wired through the circuit board. A light receiving device 6 incorporating a circuit IC element or a peripheral circuit IC element including a light receiving element is wired to a predetermined wiring 9 by solder 8 via a lead frame 7. The light emitting device 1 and the light receiving device 6 are optically coupled to each other through optical connectors 12 attached to both ends of the optical fiber cord 11, and the signal converted from electrical to optical by the light emitting device 1 is optically coupled to the light receiving device 6. It is designed to perform electrical conversion.

Next, according to FIGS. 2 and 3, this light emitting device 1,
The structure of the light receiving device 6 and the structure of the optical connector provided at the end of the optical fiber cord 11 attached thereto will be explained. In the figure, the same reference numerals as in FIG. 1 indicate the same parts.

That is, a photoelectric element 21 for emitting or receiving light is embedded together with a portion of the lead frames 2 and 7 in a first envelope 22 made of a molded body of transparent epoxy resin or the like. The optically polished end face 1 of the fiber 11 1 of the optical fiber cord ₁₁ is connected to the outside of the enclosure 22 via the optical connector 12 .
1a and the photoelectric element 21 are provided with a second envelope 23 made of a molded body made of a light shielding member except for the part where the photoelectric element 21 is optically coupled. The lead frames 2 and 7 protrude, and a holding portion 24 for holding the optical connector 12 is provided on a surface substantially perpendicular to this surface. The optical connector 12 also has a flange integrally formed at a predetermined position, which has a hole at the end of the optical fiber cord 11 that extends along the axis of the substantially cylindrical main body 13 and into which the optical fiber cord ₁₁ and the fiber 111 are inserted. 14
The optical connector 12 has a locking part 15 that fits into the holding part 24, and a caulking ring 16 that fixes the optical connector 12 and the optical fiber cord to the rear end of the optical connector 12.

However, as can be seen from FIGS. 2 and 3, the photoelectric devices 1 and 6 having such a structure are connected and fixed to the circuit boards 5 and 10 by connecting the lead frames 2 and 7 to predetermined positions on the circuit boards 5 and 10. It is connected to the wires 4 and 9 with only solders 3 and 8, and the optical connector 1
When snapping in the lead frames 2 and 7, a force in the direction of the arrow 17 is applied and the lead frames 2 and 7 are work-hardened and then broken.The photoelectric element 21, especially the light-receiving element, is prone to malfunction due to external electrical noise. Since both the first envelope 22 and the second envelope 23 are made of molded bodies made of insulators, they have electrical defects that easily cause this malfunction.

Various structures have been considered to prevent this electrical defect, but all of them cause secondary problems and cannot be called perfect structures. For example, a structure in which a transparent conductive film is formed on the outer surface of the transparent first envelope 22 can be expected to have a shielding effect against electrical noise from the outside; It is extremely difficult to selectively establish electrical continuity with. Furthermore, it is not necessarily easy to form a transparent conductive film on the surface of the first envelope 22 at low temperatures.

As a countermeasure to this problem, as shown in FIG.
1 is placed in a metal container 33 with a transparent window 32 made of glass or the like on one side, and the ground lead pin 38 ₁ of the lead pins 38 inserted through the stem 34 of this metal container is grounded. Such containers are expensive, and in order to snap in the optical connector from the lateral direction as described above, a step of bending the lead pins 38 is required, and the lead pins are also easily deformed due to the rotation axis in the direction of the arrow 17.

The present invention was made in view of the various drawbacks of the conventional photoelectric devices mentioned above, and is easy to fix on a circuit board.
The object of the present invention is to provide a photoelectric device that is mechanically stable and can be easily electrically shielded.

Next, an embodiment of the photoelectric device of the present invention will be described with reference to FIGS. 5 and 6. Optical fiber cord in the diagram,
Since the optical connectors, lead frames, etc. are almost the same, the same reference numerals will be used and no particular explanation will be given.

That is, the photoelectric devices 1 and 6 include a photoelectric element for emitting or receiving light, or a photoelectric element, and an IC element for a peripheral circuit, or an IC element for a peripheral circuit (hereinafter simply referred to as a photoelectric element) 41 including a photoelectric element, on a predetermined lead frame 2,
A first envelope 42 made of a molded body of transparent epoxy resin or the like is formed so as to bury parts of the lead frames 2 and 7 and the photoelectric element 41. A second envelope 4 made of a conductive member is molded or fixed on the outside of the envelope 42, and has a holding portion 44 on a part of which performs optical coupling by snap-in with an optical connector.
Consists of 3. At the exits of the lead frames 2 and 7 of this second envelope 43, an opaque adhesive layer 45 is provided which also serves as light shielding and fixing. The pin 46 implanted in the second envelope 43 can be fixed to the ground circuits 4a, 9a via the circuit boards 5, 10 with solders 3a, 8a. Further, the second envelope includes lead frames 2 and 7.
The recess 50 is provided to prevent deterioration of the positional accuracy of the photoelectric element due to electrical contact with the lead frame and irregular shapes of the cut portion of the lead frame.

The material of the second envelope 43 is, for example, a plastic molded product containing carbon, and the electrical conductivity can be controlled to a certain degree depending on the carbon content. It is only necessary to mix carbon with the materials, and unlike the formation of the transparent conductive film described above, the process is simple. Of course, carbon may be replaced with metal powder or other material that increases conductivity, and if workability is considered, metal molding or other methods with good workability may be used. A thin copper wire is sufficient for the pin 46, and the electrical contact with the second envelope 43 may be made by press-fitting a conductive adhesive or may be formed as a protrusion during molding of the second envelope 43. .

As a modification of the above embodiment, the ground leads of the lead frames 2 and 7 are bent and passed through the second envelope 43 from the plane formed by the other lead frames 2 and 7, although the workability is somewhat lowered. It may be made to come out from a spaced apart position. Further, the pin 46 may be a metal screw or the like, or may be a pin or protrusion with the same thickness as the lead frames 2 and 7.
It is also possible to use boards and electrical connectors.

Further, the second envelope 43 does not need to be made of an integral part, and may be formed into parts, and if it is divided, it is not necessary that all of the parts are made of conductive material. That is, for example, a part made of a conductive material is fixed over a part or the entire area of the first envelope 42 including the photoelectric element 41, and a conductive pin that is fixed in contact with this part is fixed to the ground wiring of the circuit board. do it. Furthermore, it goes without saying that the optical coupling between the light emitting device/light receiving device and the optical fiber cord does not necessarily require the use of an optical connector, but may be structured such that the second envelope 43 and the optical fiber cord are directly fixed. .

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an optical transmission circuit, Fig. 2 is a cross-sectional view showing an example of the relationship between a photoelectric device, an optical fiber cable, and an optical connector, Fig. 3 is a bottom view of the photoelectric device in Fig. 2, and Fig. 4 is an explanatory diagram showing an optical transmission circuit. The figure is a cross-sectional view showing another example of the photoelectric device, and FIGS. 5 and 6 are views showing one embodiment of the photoelectric device of the present invention. FIG. 5 is the relationship between the photoelectric device, the optical fiber cable, and the optical connector. FIG. 6 is a bottom view of the photoelectric device of FIG. 5. 1... Light emitting device, 6... Light receiving device, 2, 7...
Lead frame, 12... Optical connector, 21, 4
1... Photoelectric element, 22, 42... First envelope,
23, 43...second envelope, 46...pin.

Claims (1)

[Claims] 1. A first envelope that holds a photoelectric element for emitting or receiving light and a part of a lead frame electrically connected thereto, and an envelope that houses the first envelope, a second envelope having a holding portion for holding an optical fiber optically coupled to the photoelectric element, at least a portion of the second envelope is made of a conductive member, and the lead frame is fixed to the ground circuit of the circuit board via a pin or a protrusion at a position spaced apart from the plane formed by the second A photoelectric device characterized in that an envelope can be supported on the circuit board.