JPH04294306A - Photoelectric converter - Google Patents

Abstract

PURPOSE:To reduce the light loss by employing structure which easily align the axis of an optical fiber and the optical axis of a photodetecting element with each other when the tip surface of the optical fiber is fitted abutting on the photodetection surface of the photodetecting element and to decrease the number of components, and decrease the assembly man-hours by providing a shielding function to a case where the components are stored without using a dedicated shield member for components (photo detecting element and amplifying circuit) which is easily affected by the external noise. CONSTITUTION:The element case 17 which contains the photodetecting element 12 and an amplifying circuit is formed of a conductive plastic molding and the opening part of the element case 17 is closed with a conductive lid 19 to improve the shield effect; and an optical fiber 5 is clamped and fixed with the guide groove of the holding part of the element case 17 and the guide groove of a presser 2 which faces it to align the optical axis of the photodetecting element and the axis of the optical fiber with each other.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric converter that converts an optical signal into an electrical signal or an electrical signal into an optical signal using a light receiving element or a light emitting element.

0002

[Prior Art] FIG. 5 is a vertical cross-sectional view of a conventional photoelectric converter.
A light receiving element 3 covered with a shield cap 2 inside the main body case 1, a printed circuit board 4 on which the light receiving element 3 is mounted, a printed circuit board 5 on which an amplifier circuit is mounted, and a printed circuit board 6 on which a processing circuit is mounted. It is housed through a shield case 7, and the light receiving element 3, amplifier circuit, and processing circuit are electrically connected in series. The optical fiber 9 that transmits the optical signal to the light-receiving element 3 is held in an optical fiber holding section 8 that is separately configured outside the main case 1, and the tip of the optical fiber 9 penetrates the side wall of the main case 1. It is in contact with the light emitting surface of the light receiving element 3. On the other hand, the tip of the electric cable 10 that leads out the electric signal converted from the optical signal passes through the side wall of the main body case 1 and the shield case 7 and is connected to the processing circuit mounted on the printed circuit board 6. . In this photoelectric converter, the optical signal from the optical fiber 9 enters the light receiving element 3, where it is photoelectrically converted into an electrical signal, and this electrical signal is amplified by the amplifier circuit and then passed through the processing circuit to the electrical cable 10. It is output from

0003

[Problem to be Solved by the Invention] In the photoelectric converter as described above, the optical fiber holding part and the mechanism for fixing the light receiving element are separately constructed parts, so when assembling these parts, it is difficult to It is difficult to align the optical axis of the element with the axis of the optical fiber, and there is a risk of so-called optical axis misalignment. If such an optical axis shift occurs, there is a drawback that the optical loss increases and the optical transmission distance becomes short. In addition, due to the layout structure of the photodetector and amplifier circuit, shield caps and shield cases that fit each part are required to shield the photodetector, the lead wires that connect the photodetector and the amplifier circuit, and the printed circuit board on which the amplifier circuit is mounted. However, there was also the problem that the number of parts increased and the number of assembly steps increased.

In view of the above-mentioned problems, the present invention is designed to reduce the number of parts and the number of assembly steps, and to easily align the optical axis of the light-receiving element with the axis of the optical fiber during assembly. The purpose is to provide a photoelectric converter.

[0005]

[Means for Solving the Problems] According to the present invention, a light receiving element for receiving an optical signal from an optical fiber, an amplifying circuit for amplifying an electrical signal from the light receiving element, and an electric cable are provided in the main body case. In a photoelectric converter incorporating a processing circuit that processes electrical signals connected and amplified by the amplifier circuit, a light receiving element and an optical fiber are each housed and held in an element case integrally molded with conductive plastic. .

[0006] In such a structure, the element case is a case with one side open, and has a storage chamber in which the photoelectric element is stored, an insertion hole that communicates with the storage chamber and stores the optical fiber, and the above-mentioned insertion hole. A conductive lid is provided to close the opening of the case, and a printed circuit board on which an amplifier circuit is mounted together with a light receiving element is housed inside the element case. , a presser for holding the optical fiber on the holding portion;
It is provided with an operating lever equipped with an eccentric cam that presses the presser, and is further provided with a plurality of small protrusions on the surfaces of the optical fiber holder and the guide groove formed in the presser.

[0007]

[Operation] According to the structure of the present invention, the optical axis of the optical fiber held between the guide groove of the optical fiber holding portion of the element case and the guide groove of the presser is perpendicular to the center of the light-receiving surface of the light-receiving element. Therefore, the axis of the optical fiber fixed by the holding part and the presser coincides with the axis of the light-receiving element. Furthermore, by providing a shielding function to the element case and the lid that closes its opening, there is no need for a dedicated shield member, reducing the number of parts and the number of assembly steps.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a longitudinal sectional view of a photoelectric converter according to an embodiment of the present invention, in which a main body case 11 houses the following parts. That is, an element case 17 that is molded from conductive plastic and has a light shielding wall 14 for forming a storage chamber 13 for the light receiving element 12 therein, an optical fiber holding part 16 on which the lower outer circumferential surface of the optical fiber 15 is placed, and the storage chamber 1
3, a printed circuit board 18 on which the light receiving element 12 housed in the housing 3 and an amplifier circuit (not shown) are mounted, a conductive lid 19 that closes the opening of the element case 17, and a printed circuit board 20 on which a processing circuit (not shown) is mounted. , a presser 21 that faces the optical fiber holder 16 and presses the outer peripheral upper surface of the optical fiber 15, and an operating lever 23 equipped with an eccentric cam 22 that presses the presser 21. The amplifier circuit and the processing circuit are connected by a lead wire 24, and the processing circuit is led out of the main body case 11 by an electric cable 25. Further, a guide groove 26 is provided in the presser 21 and the holding part 16 along the axial direction of the optical fiber 15 to be held and perpendicular to the center of the light receiving surface of the light receiving element 12. 2 and 3 are views taken along arrow P in FIG. 1 and show the cross-sectional shape of the guide groove 26. FIG. 2 shows the guide groove 26 having a semicircular cross-sectional shape, and a plurality of small protrusions 27 are provided on the surface of the guide groove 26 to prevent the optical fiber 15 from slipping (preventing it from coming off).
It is said that FIG. 3 shows the guide groove 26 having a V-shaped cross section, and a plurality of small protrusions 27 are provided on the surface of the guide groove 26 to prevent the optical fiber 15 from slipping (preventing it from coming off).

When attaching the optical fiber 15 to a photoelectric converter having the structure shown in FIG.
and insert the optical fiber 15 into the guide groove 26 of the holding part 16,
The tip end surface is brought into contact with the light receiving surface of the light receiving element 12. In this state, if the operating lever 23 is operated and moved in the direction of arrow Q, the eccentric cam 22 presses the presser 21, and the outer diameter of the optical fiber 15 is held between the guide groove of the presser 21 and the guide groove of the holding part 16. The optical fiber 15 is then fixed. FIG. 4 shows a longitudinal cross-sectional view of the photoelectric converter in this state. When an optical signal is transmitted to the optical fiber 15 of this photoelectric converter, the optical signal enters the light receiving element 12 and is converted into an electrical signal, and this electrical signal is amplified by an amplifier circuit mounted on the printed circuit board 18. The signal is then output from the electric cable 25 via the processing circuit mounted on the printed circuit board 20. Here, the light-receiving element 12 and the amplifier circuit, which are susceptible to external noise, are completely shielded by the conductive element case 17 and the conductive lid 19, so that they are not affected by external electromagnetic interference. Note that since the electrical signals after the amplification circuit have been amplified, the voltage level is high and is not affected by external noise. Therefore, the printed circuit board 20 on which the processing circuit is mounted, the lead wire 24, and the electric cable 25 do not need to be shielded.

The photoelectric converter described above is an embodiment for converting an optical signal into an electrical signal, but when used for converting an electrical signal into an optical signal, the light receiving element 12 in FIGS. 1 and 4 is used to emit light. All you have to do is replace the element. In other words, the electrical signal input from the electrical cable 25 is sent to the printed circuit board 2.
The processing circuit mounted on the PC board 18 is amplified by the amplifier circuit mounted on the printed circuit board 18, and converted into an optical signal by a light emitting element. This optical signal is emitted from the optical fiber 15. Note that if you want to perform both conversion from optical signal to electrical signal, or from electrical signal to optical signal, use the light receiving element 1 in Figs. 1 and 4.
The light emitting signal may be stored in parallel to 2.

[0011]

According to the present invention, the axes of the guide grooves of the holding part and the holding part that hold the optical fiber are aligned with the optical axis of the light-receiving surface of the light-receiving element, so that the optical fiber can be held between the two guide grooves. By operating the operating lever, the optical fiber can be fixed without causing optical axis deviation. In addition, the light receiving element, amplifier circuit, etc., which are easily affected by external noise, are housed inside the conductive case and conductive lid, so a sufficient shielding effect can be expected, eliminating the need for a separate shielding member and reducing the number of parts. , and the assembly man-hours are also reduced.

[Brief explanation of drawings]

[Fig. 1] A vertical cross-sectional view of a photoelectric converter that is an embodiment of the present invention.

[Fig. 2] A front view of a guide groove with a semicircular cross-sectional shape as seen from the direction of arrow P in Fig. 1.

[Fig. 3] A front view of a guide groove having a V-shaped cross section as seen from the direction of arrow P in Fig. 1.

[Figure 4] Cross-sectional view of the photoelectric converter shown in Figure 1 with an optical fiber attached

[Figure 5] Longitudinal cross-sectional view of a conventional photoelectric converter

[Explanation of symbols]

11 Main case 12 Photo receiving element 13 Storage room 14　　　　Light-blocking wall 15 Optical fiber 16 Holding part 17 Element case 18 Printed circuit board 19 Lid 20 Printed circuit board 21 Presser 22 Eccentric cam 23 Operation lever 25 Electric cable 26 Guide groove 27 Small projection

Claims (5)

[Claims] Claim 1: A light-receiving element that receives an optical signal from an optical fiber, an amplification circuit that amplifies an electrical signal from the light-receiving element, and a light-receiving element that is connected to an electric cable and amplified by the amplification circuit. 1. A photoelectric converter incorporating a processing circuit for processing electrical signals, characterized in that a light receiving element and an optical fiber are each housed and held in an element case integrally molded with conductive plastic. 2. In the device according to claim 1, the device case is a case with one side open, and has a storage chamber for storing the photoelectric device therein, and an insertion hole communicating with the storage chamber for storing the optical fiber. A photoelectric converter comprising: and a conductive lid that closes the opening of the case. 3. A photoelectric converter according to claim 1, wherein a printed circuit board on which an amplifier circuit is mounted together with a light receiving element is housed inside the element case. 4. The apparatus according to claim 1, further comprising: a holding part for holding the optical fiber; a presser for holding the optical fiber on the holding part; and an eccentric cam for pressing the presser. A photoelectric converter characterized in that it is equipped with an operating lever. 5. A photovoltaic device according to claim 1, characterized in that a plurality of small protrusions are provided on the surface of the guide groove formed in the optical fiber holder and the presser. converter.