JPH056896U - Optical modem device shield structure - Google Patents

Abstract

(57) [Abstract] [Purpose] A main case 20 accommodating a main circuit board 50 and a rotating case 30 accommodating a photoelectric conversion circuit board 51 and rotatably attached to the main case 20 are provided. Then
The main circuit board 50 of the main case 20 and the rotating case 3
In the optical modem device electrically connected to the photoelectric conversion circuit board 51 of No. 0 by the connection cable 11, the electromagnetic noise radiated from the connection cable 11 arranged in the rotating case 30 on the board 51. (EN) Provided is a shield structure for obtaining a small-sized optical modem device which prevents an influence on the optical signal amplifier circuit 63 and has excellent workability in assembling the rotating case 30. A flexible insulating metal foil 40 provided with an insulating coating 41 is arranged between a photoelectric conversion circuit board 51 arranged in a rotating case 30 and a connection cable 11 and a ground connection portion is formed on the flexible metal foil 40. 44,
A notch 45 is provided along the vicinity of the ground connection 44.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a shield structure for an optical modem device, which includes a main case and a rotating case rotatably attached to the main case.

[0002]

[Prior Art]

 In recent years, for example, an optical communication system has been widely used in which a computer and an automatic control device, a LAN node and a terminal device, a host computer and a terminal computer, etc. are connected by an optical fiber cable and information is transmitted by an optical signal. In an optical communication system in which information processing devices are connected by an optical fiber cable, an optical modem device for converting between electric signals and optical signals is used. These optical modem devices are required to have excellent noise resistance characteristics, and it is desirable that they are small in size and that they can be installed from any direction without bending the optical fiber cable. As such an optical modem device, there is an optical modem device as shown in FIGS. 3 and 4 proposed by the present applicant in Japanese Utility Model Publication No. 3-6348. The optical modem device 1 is composed of a main case 20 and a rotating case 30 rotatably attached to the main case 20, and a main circuit constituting a main circuit portion housed in the main case 20. The substrate 50 and the optical / electrical or / and electrical / optical conversion circuit substrate (hereinafter abbreviated as photoelectric conversion circuit unit) that constitutes the optical / electrical or / and electrical / optical conversion circuit unit housed in the rotating case 30 ( (Hereinafter abbreviated as photoelectric conversion circuit board) 51 is electrically connected by a connection cable 11. The optical fiber cable 3 is connected to one end of the rotating case 30.

An optical receptacle 60 having a light emitting element for outputting an optical signal and a light receiving element for receiving the optical signal is provided on the photoelectric conversion circuit board 51 housed in the rotating case 30, and the optical receptacle 60 is provided. An optical connector 12 to which the optical fiber cable 3 is connected is connected to. Further, the photoelectric conversion circuit board 51 is provided with an amplifier circuit 63 composed of an integrated circuit for amplifying an optical signal, and the main circuit board 50 on the main case side and the board 51 are electrically connected near the amplifier circuit 63. A small connector 14 for the connecting cable 11 is provided.

[0004]

[Problems to be solved by the device]

 Since it is necessary to make the rotating case as small as possible, the photoelectric conversion circuit board inside the rotating case is densely packed with photoelectric conversion parts, amplifier circuits, small connectors, etc., and is placed inside the rotating case. Due to the structure of the case, the signal line and power supply line of the connection cable had to be arranged close to the input terminal of the amplifier circuit. Therefore, the electromagnetic noise radiated from the connection cable could affect the input terminal of the amplifier circuit. As means for preventing the effect of this electromagnetic noise, measures such as sufficiently separating the amplifier circuit and the connection cable, shielding the amplifier circuit section with a metal plate such as permalloy, and using a coaxial cable for the connection cable can be considered. However, all of these electromagnetic noise prevention measures have the drawbacks of increasing the size of the optical modem device as a result, and also have difficulty in assembly workability and cost of the rotating case.

The present invention provides a shield structure for an optical modem device which solves the above-mentioned drawbacks by a simple means and prevents the influence of electromagnetic noise.

[0006]

[Means for Solving the Problems]

 A main case in which the main circuit section is housed; and a rotating case that houses the optical / electrical and / or electric / optical conversion circuit section and is rotatably attached to the main case. An optical modem device in which a main circuit part of a main case and an optical / electrical or / and electric / optical conversion circuit part of the rotating case are electrically connected by a connecting cable, the optical modem device being arranged in the rotating case. A flexible metal foil coated with an insulating film is disposed between the optical / electrical or / and electric / optical conversion circuit portion and the connection cable, and a ground connection portion is provided on the flexible metal foil to provide the flexible insulation. A notch is provided along the vicinity of the ground connection of the metal foil.

[0007]

[Action]

 Due to the miniaturization of the rotating case and the high-density mounting of the photoelectric conversion circuit board in the rotating case, the flexible insulating metal foil can be used even for the unevenness of electronic parts on the photoelectric conversion circuit board and the narrow gap in the rotating case. As a result, the electromagnetic shield between the circuit board and the connection cable is completely completed, and the influence of the electromagnetic noise radiated from the connection cable on the amplifier circuit is prevented. In addition, the notch provided along the ground connecting part of the flexible insulating metal foil prevents warping of the flexible insulating metal foil that occurs when the ground connecting part is soldered to the ground, and the flexible insulating metal foil is prevented. This facilitates soldering work and assembly of the rotating case.

[0008]

【Example】

 The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an essential part of an optical modem device provided with a shield structure of the present invention, and FIG. 2 is an explanatory view of a flexible insulating metal foil used in the present invention. The same parts as those of the conventional optical modem device will be described with reference to FIGS. 3 and 4. In FIGS. 1 and 2, reference numeral 30 denotes a rotating case formed by combining half rotating case members 31 and 32 made of insulating resin. The rotating case 30 is rotatably held by the main case 20 which houses the main circuit board 50, and the main case 20 and the main circuit board 50 housed in the rotating case 30 and the photoelectric conversion circuit board 51. Are electrically connected by a connection cable 11. Reference numeral 40 is a flexible metal foil with an insulating coating, 41 is an insulating coating, and 42 is a metal foil to form a ground pattern. Reference numeral 44 is a ground connection portion, and 45 is a cut portion.

A photoelectric conversion circuit board 51, which constitutes one electronic circuit of the optical modem device, is housed inside the member formed by combining the half members 31 and 32 of the rotating case. An optical receptacle 60 is soldered on one surface of the board 51, and an amplification circuit 63 for amplifying a received light signal is arranged on the other surface of the board 51. A small connector 14 for the connection cable 11 is soldered near the amplifier circuit 63. A terminal 52 electrically connected to the ground of the photoelectric conversion circuit board 51 is provided on one end side of the photoelectric conversion circuit board 51.

The shield structure of the optical modem device of the present invention is configured by disposing the flexible insulating metal foil 40 between the connection cable 11 and the photoelectric conversion circuit board 51, which are arranged in the rotating case 30. To be done. The flexible insulating metal foil 40 includes a metal foil ground pattern 42 having a surface coated with an insulating film 41, a ground connection portion 44 having a through hole 46 for grounding the metal foil ground pattern 42, and the ground connection portion 44. The cutout portion 45 is provided along the vicinity, and the ground connecting portion through hole 46 of the flexible insulating metal foil 40 is inserted into the terminal 52, and the ground connecting portion 44 and the terminal 52 are connected by soldering.

The optical modem device provided with the shield structure of the present invention is improved by 1.5 dB in the minimum light receiving level showing the noise resistance characteristic value, as compared with the conventional optical modem device.

[0012]

[Effect of the device]

 According to the present invention, a flexible case is provided for an extremely narrow inner space rotation case of an optical modem device having a main case and a rotation case rotatably attached to the main case. A suitable shield structure can be obtained by a simple means of disposing an insulating metal foil, and as a result, a small optical modem device excellent in noise resistance can be obtained. Furthermore, the flexible insulating metal foil does not cause warpage during soldering, has excellent workability in soldering to a circuit board, and facilitates workability in assembling a rotating case.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part for explaining a shield structure of the present invention.

FIG. 2 is an explanatory view of a flexible insulating metal foil used in the present invention.

FIG. 3 is a partially cutaway sectional view showing an assembled state of a rotatable optical modem device.

FIG. 4 is an exploded perspective view illustrating a rotatable optical modem device.

[Explanation of symbols]

 1 Optical Modem Device 3 Optical Fiber Cable 11 Connection Cable 12 Optical Connector 14 Small Connector 20 Main Case 21, 22 Case Member 30 Rotating Case 31, 32 Rotating Case Member 40 Flexible Insulating Metal Foil 41 Insulating Film 42 Ground Pattern 44 Ground Connection Part 45 notch part 46 through hole 50 main circuit board 51 photoelectric conversion circuit board 52 ground terminal 63 amplifier circuit

Claims (1)

[Claims for utility model registration] [Claim 1] A main case in which the main circuit section is housed
An electrical or / electrical / optical conversion circuit unit is housed, and a rotating case rotatably attached to the main case is provided, and the main circuit unit of the main case and the optical case of the rotating case are provided. In an optical modem device in which a power cable and / or a power / optical conversion circuit section is electrically connected with a connection cable, the light / power or / and the power / optical conversion circuit section is disposed in the rotating case. A flexible metal foil coated with an insulating coating is arranged between the connection cable and a ground connection portion is provided on the flexible metal foil, and a cut portion is provided along the vicinity of the ground connection portion of the flexible insulating metal foil. A shield structure for an optical modem device characterized by the above.