Tap device of cable broadcasting system

• US 6,560,778 B1
• Filed: 03/22/2000
• Issued: 05/06/2003
• Est. Priority Date: 03/29/1999
• Status: Expired due to Fees

• Current Assignee: Masprodenkoh Kabushikikaisha.
• Original Assignee: Masprodenkoh Kabushikikaisha.
• Inventors: Hasegawa, Shinji
• Primary Examiner(s): Faile, Andrew
• Assistant Examiner(s): Chung, Jason
• Application Number:
  US09/532,262
• Time in Patent Office: 1,140 Days
• Field of Search: 725/127-128, 725/149, 333/132, 333/134, 333/136, 333/101, 333/103, 333/104, 333/116, 333/100, 174/35.R, 174/50, 174/59, 174/60, 361/816, 361/818
• US Class Current: 725/149
• CPC Class Codes: H05K 9/0007 Casings standardised racks H05K9/0062

Abstract

There is disclosed a tap device for branching a part of transmission signals running through a transmission line to selectively transmit branched signals to subscriber terminal devices via tap output terminals, in which signal paths for leading the transmission signals to the tap output terminals can easily and securely be shielded. Substrates provided with various circuits and the like are successively fixed to a housing member provided with tap output terminals. The housing member is provided with partition walls for surrounding the signal paths to the tap output terminals from the first substrate and separating relays disposed on the substrate. A shield cover, which can separate wiring patterns for signal input to the relays and wiring patterns for signal output via the relays, is disposed between the first and the second substrates. The second substrate is fixed to the housing member via the shield cover.

Claims

1. A tap device of a cable broadcasting system, comprising:

a sealed housing comprising a pair of conductive first and second housing members having openings which can be engaged with each other, said first housing member being provided with a pair of input and output terminals for connecting the tap device to a transmission line leading to a terminal side from a center equipment of the cable broadcasting system, said second housing member being provided with a plurality of tap output terminals for branching and transmitting a transmission signal running through said transmission line to subscriber terminal devices;

a directional coupler for connecting said input and output terminals, passing the transmission signals running through said transmission line, and branching a part of the transmission signals;

a splitter for distributing the transmission signals branched by the directional coupler and transmitting the distributed signals to said tap output terminals;

a plurality of relays for connecting/disconnecting signal paths leading to said tap output terminals from the splitter;

a receiving circuit for taking in the transmission signals branched by said directional coupler and receiving a command signal superimposed onto the transmission signals and directed to the tap device from said center equipment; and

a control circuit for driving said relays in response to the command signal received by the receiving circuit to control connected/disconnected states of said signal paths in accordance with a command from said center equipment, said directional coupler, said splitter, said plurality of relays, said receiving circuit, and said control circuit being housed in the sealed housing, wherein

a splitter substrate with said splitter and said relays mounted thereon, a control circuit substrate with said receiving circuit and said control circuit mounted thereon, and a directional coupler substrate with said directional coupler mounted thereon are arranged in order from said second housing member in said sealed housing,

said plurality of relays are mounted, and grounding patterns for surrounding the relays and connecting portions of the relays and the tap output terminals on said second housing member are formed on the surface of said splitter substrate facing said second housing member, and

partition walls for surrounding said tap output terminals and abutting said grounding patterns of said splitter substrate to separate said relays and the connecting portions of the relays and said tap output terminals are disposed on the surface of said second housing member facing said splitter substrate.

2. The tap device of the cable broadcasting system according to claim 1, wherein

a wiring pattern for transmission signal input to said relays and a wiring pattern of transmission signal output via said relays are formed on the surface of said splitter substrate facing said control circuit substrate, and a grounding pattern is formed between the wiring patterns, and

a shield cover is disposed between said splitter substrate and said control circuit substrate, said shield cover comprising a plate portion which can cover the wiring patterns leading to said relays from said splitter, and a partition wall portion disposed on the surface of the plate portion on the side of the splitter substrate for abutting the grounding pattern of said splitter substrate to separate the wiring pattern for the transmission signal input to said relays and the wiring pattern for the transmission signal output via said relays.

3. The tap device of the cable broadcasting system according to claim 2, wherein screw holes are made in said splitter substrate and said shield cover to simultaneously fix the splitter substrate and the shield cover to said second housing member, and

said splitter substrate and said shield cover are simultaneously screwed to a substrate fixing portion formed on said second housing member by inserting substrate fixing screws into said screw holes.

4. The tap device of the cable broadcasting system according to claim 3, wherein a substrate fixing portion for fixing said control circuit substrate is formed on said shield cover, and said control circuit substrate is screwed to the substrate fixing portion formed on said shield cover by inserting the substrate fixing screw to the screw hole made in the position of the control circuit substrate corresponding to the substrate fixing portion of the shield cover.

5. The tap device of the cable broadcasting system according to claim 4, wherein a base for attaching said directional coupler substrate is mounted on said control circuit substrate, and said directional coupler substrate is fixed to said control circuit substrate via a resin case which has an attaching portion to the base.

6. The tap device of the cable broadcasting system according to claim 5, wherein said directional coupler substrate comprises a connector which can be attached to a directional coupler connecting connector fixed on said first housing member, and when the opening of said first housing member is engaged with the opening of said second housing member, the directional coupler substrate is connected to the input and output terminals on said first housing member via said connector.