JP2015185623A - Flexible cable grounding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible cable (FC) grounding structure which has a simple configuration and in which workability for electrically grounding a shield tape is improved.SOLUTION: Disclosed is a grounding structure of an FC 11 whose circumference is wound by a shield tape 13 electrically relaying and connecting one circuit board 4 and the other circuit board 5 installed in a case 8 with a space from the bottom surface. Bellows parts 13a, 13b are provided whose shape is maintained by being energized in the lateral direction from relay connection parts (connection terminals 6, 7) on both sides, upper ends 13a1 of the bellows parts 13a, 13b are pressed by a pressing member 9 and then the shield tape 13 abuts on the bottom surface of the case 8, thereby the shield tape 13 is electrically grounded to at least one of the pressing member 9 and the case 8.

Description

  The present invention relates to a grounding structure of a flexible cable (FC) for electrically relay-connecting circuit wiring of a circuit board such as a printed circuit board (PCB).

  One example of a conventional flexible flat cable (FFC) is shown in FIG. FIG. 3A is a plan view of an FFC in which circuit wirings of two circuit boards are electrically connected to each other, and FIG. 3B is a cross-sectional view taken along line C1-C2 in FIG. The FFC 1 is, for example, for electrically relaying and connecting one circuit board 4 and the other circuit board 5 which are installed in the case 8 of the electrical equipment with a space from the bottom surface thereof, such as aluminum (Al) or the like. The periphery is wound by a shield tape 3 made of The FFC 1 is a planar cable having a plurality of conductor wires 2 arranged in parallel in a plane and a protective insulating material made of resin or the like covering the conductor wires 2. The shield tape 3 prevents noise from entering the electric signal transmitted by the signal transmission conductor 2 of the FFC 1 from outside and prevents the electric signal transmitted by the conductor 2 from leaking to the outside. Provided. In FIG. 3, reference numerals 6 and 7 denote connection terminals (connectors) for electrically connecting the conductor wire 2 of the FFC 1 to the circuit wiring of the circuit boards 4 and 5.

  As shown in FIG. 3, the FFC 1 is provided in a plane so as to connect the circuit wirings of the circuit boards 4 and 5 to each other at a shortest distance. Further, when viewed from the cross-sectional view of FIG. 3B, the FFC 1 is linearly provided.

  When the FFC 1 is in an electrically floating state as shown in FIG. 3, the electromagnetic shielding (shielding) property is insufficient. Therefore, for the purpose of improving the shielding property, as shown in FIG. 4, a shield tape 3a having ground connection portions 3b at both ends in the signal transmission direction may be used. The connecting portion 3b is electrically connected to the ground terminals of the connectors 6 and 7. As another conventional example, there is known an FFC including a jumper member having one side electrically connected to the shield tape and the other side extending outside the cable body of the FFC and connected to the ground (see Patent Document 1). reference).

JP 2007-95435 A

  However, in the conventional FFC 1 shown in FIG. 4, the shield tape 3a having the ground connection portions 3b at both ends in the signal transmission direction has a complicated shape and is difficult to process during manufacture. Since many pieces cannot be cut out from the base material as compared with the rectangular shield tape, the manufacturing cost is increased and the product tends to be expensive. Furthermore, since it is necessary to connect the connecting portion 3b to the ground terminals of the connectors 6 and 7, there is a problem that workability when the FFC 1 is incorporated in the case 8 is poor.

  In addition, since the FFC disclosed in Patent Document 1 has a separate jumper member, the manufacturing process of the FFC is increased and the cost becomes high, and it is necessary to stop the jumper member with a screw. For this reason, there is a problem that workability when the FFC is incorporated in a case or the like is poor.

  The present invention has been completed in view of the above problems, and its object is to provide a grounding structure for a flexible cable (FC) having a simple structure and improving workability for electrically grounding a shield tape. It is to be.

  The grounding structure of the flexible cable of the present invention is wound around by a shielding tape that electrically connects and connects one circuit board and the other circuit board that are spaced apart from the bottom surface in the case. A flexible cable grounding structure having a bellows portion that maintains its shape by being biased laterally from the relay connection portions on both sides, and the upper end of the bellows portion is pressed by a pressing member, and the shield tape Is in contact with the bottom surface of the case so that the shield tape is electrically grounded to at least one of the pressing member and the case.

  In the grounding structure for a flexible cable of the present invention, preferably, at least one of the pressing member and the case is made of a conductive material and is electrically grounded.

  In the flexible cable grounding structure of the present invention, preferably, at least one of the pressing member and the case is provided with a grounding conductor at a portion where the shield tape abuts.

  The grounding structure of the flexible cable of the present invention is wound around by a shielding tape that electrically connects and connects one circuit board and the other circuit board that are spaced apart from the bottom surface in the case. A flexible cable grounding structure having a bellows portion that maintains its shape by being biased laterally from the relay connection portions on both sides, and the upper end of the bellows portion is pressed by a pressing member to Since the shield tape is electrically grounded to at least one of the pressing member and the case by coming into contact with the bottom surface of the case, the shield tape can be attached to the pressing member by simply incorporating a flexible cable into the case and pressing it with the pressing member. It contacts with at least one of the cases and is electrically grounded. That is, the grounding structure of the flexible cable of the present invention has a simple configuration and improved workability for electrically grounding the shield tape.

  In the flexible cable grounding structure of the present invention, preferably, at least one of the pressing member and the case is made of a conductive material and is electrically grounded, so that the workability of grounding the flexible cable is improved.

  In the grounding structure of the flexible cable of the present invention, preferably, at least one of the pressing member and the case is provided with a grounding conductor at a portion where the shield tape contacts, so that the workability of grounding the flexible cable is improved. .

1A and 1B are diagrams showing an example of an embodiment of a grounding structure for a flexible cable according to the present invention. FIG. 1A is a plan view of a flexible cable incorporated in a case, and FIG. It is sectional drawing in the -A2 line. FIG. 2 is a diagram showing another example of the embodiment of the grounding structure of the flexible cable according to the present invention, wherein (a) is a plan view of the flexible cable incorporated in the case, and (b) is B1 of (a). It is sectional drawing in the -B2 line. 3A and 3B are diagrams showing an example of a conventional flexible flat cable, where FIG. 3A is a plan view of the flexible flat cable incorporated in the case, and FIG. 3B is a cross-sectional view taken along line C1-C2 of FIG. It is. FIG. 4 is a view showing another example of the conventional flexible flat cable, and is a plan view of the flexible flat cable incorporated in the case.

  Embodiments of a grounding structure for a flexible cable (FC) according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of an embodiment of the FC of the present invention, where (a) is a plan view of the FC incorporated in the case, and (b) is a cross section taken along line A1-A2 of (a). FIG. As shown in FIG. 1, the grounding structure of the FC11 of the present invention electrically connects one circuit board 4 and the other circuit board 5 that are installed in the case 8 with a space from the bottom surface thereof. The grounding structure of the FC 11 is wound around by a shield tape 13 and is attached in the lateral direction (the white arrow in FIG. 1B) from the relay connection portions (connection terminals 6 and 7 in FIG. 1). It has bellows 13a, 13b that maintains its shape by being biased, and the upper end 13a1 of the bellows 13a, 13b is pressed by the pressing member 9 so that the shield tape 13 comes into contact with the bottom surface of the case 8 to thereby shield the tape. Reference numeral 13 denotes a configuration in which at least one of the pressing member 9 and the case 8 is electrically grounded. With this configuration, the shield tape 13 comes into contact with at least one of the pressing member 9 and the case 8 and is electrically grounded simply by incorporating the FC 11 into the case 8 and pressing it with the pressing member 9. That is, the grounding structure of the FC11 of the present invention has a simple configuration and improved workability for electrically grounding the shield tape 13.

  In the grounding structure of the FC11 of the present invention, the case 8 is used as a container for liquid crystal display devices, DVD players, copiers, printers, scanners, and other electronic devices and electrical devices. Examples of the material of the case 8 include non-conductive materials such as plastics such as acrylic resin, polycarbonate, polyamide, polyimide, polyamideimide, ceramics such as alumina ceramic, or aluminum (Al), copper, stainless steel, brass (Cu-Zn). An electrically conductive material such as an alloy is used. The case 8 may be formed by forming a conductive plating layer made of a metal, an alloy or the like on the surface of a base made of a nonconductive material such as plastic or ceramic.

  The case 8 accommodates one circuit board 4 and the other circuit board 5 that are spaced from the bottom surface. In general, the circuit boards 4 and 5 are rarely placed directly on the bottom surface of the case 8 and are installed on the bottom surface of the case 8 via a heat dissipation member, an insulating member, a buffer member, an adhesive, or the like. There are many. Therefore, the circuit boards 4 and 5 in the present invention are installed in the case 8 with a space from the bottom surface. The circuit boards 4 and 5 are made of a printed wiring board (PCB) or the like.

  The FC 11 has a plurality of conductor wires 2 made of copper (Cu) or the like, which are arranged in parallel in a plane, and a protective insulating material made of a resin or the like that covers the conductor wires 2. It has a cable. Further, the periphery of the FC 11 is wound by the shield tape 13, whereby the shield tape 13 receives electromagnetic noise from the outside with respect to the electric signal transmitted by the signal transmission conductor 2 of the FC 11. This prevents the electrical signal transmitted by the conductor wire 2 from leaking to the outside as an electromagnetic wave. The shield tape 13 is a sheet-like tape, film, sheet or the like made of a metal such as aluminum (Al). The shield tape 13 may be formed by forming a metal film such as aluminum, copper, silver, or gold on the surface of a planar substrate made of a non-conductive material such as plastic by a plating method or the like.

  As shown in FIG. 1, the FC 11 according to the present invention has a bellows portion in which the number of bellows portions (folded portions) 13 b in contact with the bottom surface of the case 8 contacts the pressing member 9 when the shield tape 13 is grounded to the case 8. The number is preferably larger than the number of portions (folded portions) 13a. In this case, the certainty of the grounding of the shield tape 13 can be improved. Note that the lower end 13b1 of the bellows portion 13b contacts the bottom surface of the case 8.

  FIG. 2 is a diagram showing another example of the embodiment of the FC according to the present invention, where (a) is a plan view of the FC 12 incorporated in the case 8, and (b) is a B1-B2 line in (a). FIG. As shown in FIG. 2, the FC 12 of the present invention has a bellows in which the number of bellows portions (folded portions) 14 a that abut against the pressing member 9 contacts the bottom surface of the case 8 when the shield tape 14 is grounded to the pressing member 9. The number is preferably larger than the number of portions (folded portions) 14b. In this case, the certainty of the grounding of the shield tape 14 can be improved. It is the upper end 14a1 of the bellows portion 14a that contacts the pressing member 9, and the lower end 14b1 of the bellows portion 14b contacts the bottom surface of the case 8.

  The pressing member 9 may be a lid that covers the FCs 11 and 12, the shield tapes 13 and 14, and the connection terminals 6 and 7. In this case, the pressing member 9 may be a flat lid or a lid having a flat plate portion and a peripheral wall portion formed so as to extend downward at the periphery of the flat plate portion.

  In the grounding structure of the FCs 11 and 12 of the present invention, it is preferable that at least one of the pressing member 9 and the case 8 is made of a conductive material and is electrically grounded. In this case, the shield tapes 13 and 14 can be grounded simply by the shield tapes 13 and 14 coming into contact with at least one of the pressing member 9 and the case 8. Therefore, the workability of the grounding of the FCs 11 and 12 is improved. In this case, at least one of the pressing member 9 and the case 8 is made of a conductive material such as aluminum (Al), copper, stainless steel, or brass (Cu—Zn alloy). Further, at least one of the pressing member 9 and the case 8 is formed by forming a conductive plating layer made of metal, alloy, etc. on the surface of a base made of non-conductive material such as plastic or ceramic, or made of metal, alloy, etc. A conductive plate or a conductive film may be attached. At least one of the pressing member 9 and the case 8 is electrically connected to an external grounding part by a grounding member (not shown) such as a grounding conductor wire.

  In the grounding structure of the FCs 11 and 12 according to the present invention, it is preferable that at least one of the pressing member 9 and the case 8 is provided with a grounding conductor at a portion where the shield tapes 13 and 14 abut. In this case, even when at least one of the pressing member 9 and the case 8 is made of a nonconductive material, the shield tapes 13 and 14 are grounded, and the shield tapes 13 and 14 are simply brought into contact with the ground conductor. 13 and 14 can be grounded. Therefore, the workability of the grounding of the FCs 11 and 12 is improved. The ground conductor may be provided directly on at least one of the pressing member 9 and the case 8, or provided on a separate circuit board or the like installed on at least one of the pressing member 9 and the case 8. It may be a thing. The grounding conductor is electrically connected to an external grounding part by a grounding member (not shown) such as a grounding conductor wire.

  Note that the FC of the present invention is not limited to the above embodiment, and may include appropriate design changes and improvements.

  The FC of the present invention is used by being housed in a case of an electronic device or an electric device. Examples of the electronic device and electric device include a DVD player, a CD player, a copier, a printer, a scanner, a personal computer, a general-purpose large computer, a tablet terminal, a memory device (buffer device), and a display device. In addition, as a display device in which the FC of the present invention is accommodated, a liquid crystal display (LCD), an organic EL (Electro Luminescence) device, an inorganic EL device, a plasma display, an FED (Field Emitting Display), an SED (SED) There are display devices such as a surface-conduction electron-emitter display (GLV) device, a GLV (grating light valve) device, a PDP (plasma display) device, an electronic paper display device, a DMD (digital micro mirror device), and a piezoelectric ceramic display.

1 FFC
2 Conductor wire 3 Shield tape 4, 5 Circuit board 6, 7 Connection terminal (connector)
8 Case 11, 12 FC
13, 14 Shield tape 13a, 13b Bellows 14a, 14b Bellows

Claims (3)

  A grounding structure for a flexible cable in which the periphery is wound by a shielding tape that electrically connects and connects one circuit board and the other circuit board that are spaced apart from the bottom surface in the case, By having a bellows part that maintains its shape by being biased laterally from the relay connection parts on both sides, the upper end of the bellows part is pressed by a pressing member, and the shield tape comes into contact with the bottom surface of the case A flexible cable grounding structure in which the shield tape is electrically grounded to at least one of the pressing member and the case.   The flexible cable grounding structure according to claim 1, wherein at least one of the pressing member and the case is made of a conductive material and is electrically grounded.   The ground structure of the flexible cable according to claim 1, wherein at least one of the pressing member and the case is provided with a ground conductor at a portion where the shield tape abuts.