GB2129219A

GB2129219A - Switching apparatus

Info

Publication number: GB2129219A
Application number: GB08228928A
Authority: GB
Inventors: Goro Takeda; Nobuo Sakurai
Original assignee: Tsuyama Mfg Co Ltd
Current assignee: Tsuyama Mfg Co Ltd
Priority date: 1982-10-08
Filing date: 1982-10-08
Publication date: 1984-05-10

Abstract

A switch comprises a printed circuit board 1 having a central contact 2 and two concentric rings of radially aligned outer contacts 3, 4. A slide contact 10 for bridging the contacts 2, 3, 4 is mounted in a spring biased rotor 11 which is rotatable in one direction only by means of a ratchet arrangement 8, 8a. <IMAGE>

Description

SPECIFICATION Switching apparatus The present invention relates to an apparatus for switching the circuits of an electronic device, and more particularly, to an apparatus for switching the circuits on a printed circuit board.

Switching of the circuits on a printed circuit board incorporated in an electronic device has heretofore been accomplished by the manipulation of a commercially available rotary or slide switch mounted on a chassis or a panel of the housing. The switch is connected to the circuit on the printed circuit board via conductors. The disadvantages of such a construction reside in the difficulty of incorporating the switch with other electronic components due to the relatively large size of the switch and in having to make a special order for a switch which is small enough for electronic device which increases the manufacturing costs.

The main object of the present invention is to provide a novel and improved switch.

Another object of the present invention is to provide a very small switch.

A further object of the present invention is to provide a switch which may be positively operated.

A still further object of the present invention is to provide a low cost switch.

The present invention consists in an apparatus for switching circuits printed on a board, comprising a printed circuit board having thereon a central contact terminal and a plurality of peripheral contact terminals disposed on at least one imaginary circular line which is coaxial with respect to the central contact terminal, said peripheral contact terminals being aligned on imaginary' radial lines extending from the central contact terminal, and a rotary means disposed along an axis normal to the central contact terminal on the board and including a rotary portion having at its lower end a slide contact member made of an electrically conductive material, said slide contact member having a length which is the same as an interval between the central contact terminal and the outer-most contact terminal whereby the slide contact member of the rotary means being rotatably biased upon the contact terminals on the board so that the rotation of the slide contact member causes the switching of the conduction pattern of the circuits on the board.

In order that the invention may be more readily understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is an exploded elevational view partly in section showing an apparatus for switching circuits printed on a board, Fig. 2 is an assembled cross-section of the apparatus shown in Fig. 1, Fig. 3 is a diagrammatic plan view of a printed circuit board, and Fig. 4 is a plan view of the switching apparatus mounted on an electronic device.

Referring to the drawings, Fig. 1 shows a switching apparatus comprising a plurality of contact terminals 2 to 4 on a printed circuit board 1, and a slide contact increment portion 5.

The contact terminals 2 to 4 which are printed on the board 1 include a central contact terminal 2 and peripheral contact terminals 3 and 4 which are spaced along a single or plurality of coaxial circular lines C1 and C2. The peripheral contact terminals 3 and 4 are aligned along a radial line.

The number of contact terminals 3 and 4 is not limited to the number of the contact terminals shown. The angle a between the radial lines extending beyond the circular lines C, and C2 is determined in accordance with the number of circuits which is used for the electronic device. It is preferable that the angle a be 3600/n (where n is a positive integer) or a positive multiplication of an integer n. There is shown the case where n is 6 so that the switching of 6 positions may be accomplished. Alternatively another angle a is possible.

The slide contact increment portion 5 is shown in detail in Figs. 1 and 2 and mainly includes a knob 7, a rotor 11 and a slide contact member 10 which are disposed along a line normal to a printed circuit board 1 and extending through the central contact 2.

The knob 7 is rotatably arranged in the bearing hole 6 of the housing A and has n number of sawtoothed projections 8a which are engaged with the projections 8 formed in the hole 6. The number of projections 8 and 8a correspond to the angle a. The knob 7 may be rotated clockwise but counter-clockwise rotatation of the knob 7 is prohibited by ratchet-operated projections 8 and 8a.

The rotor 11 comprises a base having a recess into which a slide contact member 10 is fitted and a substantially cyiindrical portion having at the upper edge thereof a recess 9a into which a projection 9 of the knob 7 is inserted. The rotor 11 is loosely fitted in the hole 6 of the housing A and is biased toward the printed circuit board 1 by a spring 12 so that the slide contact 10 may be in positive contact with the peripheral contact terminals 2 to 4. The knob 7 is fastened to the rotor 11 by means of a fastening screw 13 which is screwed into the upper end of the rotor 11.

The rotor 11 is operatively connected with the knob 7 by means of the screw 13 and the projection 9 engaged in the recess 9a of the rotor 11 so that clockwise rotation of the knob 7 causes the rotor 11, in turn, the slide contact member 10 to rotate clockwise in order to conduct a switching operation.

The slide contact member 10 is made of an electrically conductive, elastic material, preferably silicon rubber with added carbon powders. Diene rubber with added carbon powders may be used.

The slide contact member 10 has a length as long as the interval between the central contact 2 and the outermost peripheral contact terminals 4. It is preferable for preventing the circuit from shorting that of the width of the slide contact member 10 be narrower than the maximum diameter of the contact terminals 2 to 4 on the printed circuit board. Notches 1 Oa are formed on upper and lower sides thereof at the position where the contact 10 is not in contact with the fixed contacts 2 to 4 for decreasing the friction resistance and possibility of contact failure. The notches 1 Oa are also useful as markers indicating the insertion direction of the slide contact member 10 into the recess of the rotor 11 for making the switch assembly operation easy.

In operation, the knob 7 is rotated clockwise by means of a screw driver or a finger. Unidirectional and incremental rotation of the knob 9, that is to say, the slide contact 10 may be accomplished by the saw-toothed projections 8 and 8a so that the slide contact member 10 positively connects the contact terminals 2 to 4 at each pOsition.

The switching apparatus described has the following advantages: (1) There is no problem of contact failure since the slide contact member 10 is springingly biased upon and in contact with the contact terminals 2, 3 and 4 printed on the board, and the switch can endure long term use since the abrasion between the contacts is limited.

(2) The switch occupies less space in the electronic device owing to the reduced size thereof. This can contribute to miniturization of the electronic device.

(3) Switching operations can be positively accomplished for complicated circuits without causing the circuit shorting and contact failure even if a number of contacts are printed on the board.

(4) The switches can be mass-produced at a low-cost since the number of parts are reduced, with the overall arrangement being reduced in size as a consequence.

(5) Contact failure and misconnection due to dislocation can be avoided since the rotor portion may be quickly incremented in latchet manner corresponding to contact position.

Claims

1. An apparatus for switching circuits printed on a board, comprising a printed circuit board having thereon a central contact terminal and a plurality of peripheral contact terminals disposed on at least one circular line which is coaxial with respect to the central contact terminal, said peripheral contact terminals being aligned on radial lines extending from the central contact terminal, and a rotary means disposed along an axis normal to the central contact terminal on the board and including a rotary portion having at its lower end a slide contact member made of an electrically conductive material, said slide contact member having a length which is identical with an interval between the central contact terminal and the outermost contact terminal whereby the slide contact member of the rotary means is rotatably biased upon the contact terminals on the baord so that the rotation of the slide contact member causes the switching of the conduction pattern of the circuits on the board.

2. An apparatus as claimed in claim 1, in which the peripheral contact terminals on the circular lines coaxial with respect to the central contact terminal are aligned on the radial lines, said radial lines being arranged so that the angle between the radial lines is 3600/n (where n is a positive integer) or a positive multiplication of n.

3. An apparatus as claimed in claim 1 or 2, in which the rotary means is accommodated in a bearing hole provided in a housing which encloses the printed circuit board, said rotary means having a plurality of saw-toothed projections which engage with the projections at the periphery of the bearing hole in ratchet-like manner, the projections corresponding to the contact terminals so that the slide contact member may be positively positioned on the contact terminals.

4. An apparatus as claimed in any one of claims 1 to 3, in which the slide contact member has a width which is smaller than the maximum diameter of contact terminals on the printed circuit board.

5. An apparatus as claimed in any one of claims 1 to 4, in which notches are provided at a side or sides parallel to the printed circuit board at a position other than the contact area.

6. An apparatus for switching circuits printed on a board, substantially as hereinbefore described with reference to Figs. 1 to 4 of the accompanying drawings.