GB2215520A - Control mechanism - Google Patents

Abstract

A rotary or sliding electrical control mechanism comprises a printed circuit board 1 having an electrically conductive track 23 thereon, and a control member 4 movable in relation to the track and having an electrically conductive wiper 5 for engagement with the track. The control member 4 may operate a gas cock as well as the wiper 5 which bridges a pair of tracks 2, 3 when the control member 4 is rotated to connect an electrical supply to an indicator light mounted on the board 1. The outer track 3 may be segmented, each segment being connected to an indicator light. A further segmented track may be provided with each segment being connected to a supplementary device. The tracks may be arcuate or linear and may be of resistive material. <IMAGE>

Description

LATINS CONTROLS This invention relates to rotary or sliding controls which provide a supplementary function. It is known to indicate the position of a rotary or sliding control by an indicator light, e.g. neon or LED, operated by conventional switch mechanically connected to the control and operated when the control is moved to one or more preselected positions.

The present invention provides a rotary or sliding control which is mounted on or behind a printed circuit board and on which board tracks are provided for contact by a conductive wiper carried on and moved with the control to provide a supplementary switch or switches. Operation of the control moves the wiper in relation to the tracks and the consequent connection or disconnection of an electrical circuit through the tracks can be used to illuminate or extinguish indicator lights or perform other supplementary functions.

Preferably the indicator lights are mounted on the printed circuit board and connected through tracks on the board to the supplementary switch or switches.

Where the control is a rotary one, the tracks can be circular, or arcuate, with the axis of rotation of the control as centre. Where the control is a sliding one, the tracks can be linear and parallel to the line of movement of the control. In each case the conductive wiper is positioned on the control so that, as the control is operated, the wiper can be rotated or slid respectively along the tracks to provide the st:ppierrentary switch as the control is operated.

In the "off" position of the control the supplementary switch may be inoperative, or may provide a connection between segments of the tracks at that point to vindicate that the control is off, e.g. by a warning light, LED or neon.

Outside the "off" position cl the control, .e ma simply be two concentric or parallel tracks, depending on the nature of the control, which, when the control is "on" are connected by the wiper to provide electrical contact between the tracks and so operate, for example, an "on" light.

Alternatively, one of the tracks may be segmented so that each of several different positions of the control can be indicated by separate means or operate a separate supplementary function.

As a further alternative there may be more than two concentric or parallel tracks to provide simultaneously a multiplicity of switching functions.

As a still further alternative one or more of the tracks may be printed in resistive material so that resistance of the circuit formed by the wiper varies with the position of the control.

The invention can be illustrated with reference to the accompanying drawing showing, by way of example, its use in controls for gas appliances. In such appliances, a knob, or more usually several knobs, are each used to rotate a cock in a gas supply line and so control the supply of gas to a burner. In this example, the gas supply line and cocks are located behind a printed circuit board through which passes the spindle of each cock on which spindle a knob for rotating the cock is provided. Also mounted on that part of the spindle between the board and the knob is an arm carrying a conductive wiper, the arm being rotatable with the knob about the axis of the spindle.

The conductive wiper can thus be moved over tracks provide on the printed circuit board.

In the accompanying drawing, Figures 1, 2 and 3 show diagrammatically various arrangements of such tracks printed on the board.

In Figure 1, the board 1 carries two separate circular tracks 2 and 3 concentric with the axis of the sup nile 4. Track 2 is connected to one pole of an electrical supply for an indicator light and the other track 5 is connected to the indicator light (not shown) mounted on the board. A conductive wiper 5 is carried on an arr.. or bush (not shown) mounted on the spindle. In the 'off position of the control, the wiper is located at position A on the board and at that point makes no electrical connection between the tracks 2 and 3.When the spindle is rotat-ed to open the gas cock the wiper is moved onto the tracks, as shown in position B, where it rakes electrical connection between the tracks, so connection the electrical supply to the indicator light. In the arrangement shown in Figure 1 the tracks may be of uniform conductivity so that the indicator light is simply off in the "off" positionof the control or on whentthe cock is open to any degree.

Alternatively, one or both of the tracks may be printed in resistive material so that the resistance of the circuit connected by the wiper will varg wit' the position of the wiper. With the connections showy ir.

Figure 1, the outer track 3 when printed in resistive material would provide the minimum resistance when the cock is just open, but this situation could be reversed by connecting the other end of the track to the indicator light.

Figure 2 shows diagrammatically an arrangement of tracks in which the inner track is the supply track as in Figure 1 but the outer track is segmented 3.1, ~.at, 3.3 and 3.4, each segment being separately connected to an indicator light. As the gas cock is opened by clockwise rotation of the spindle the conductive wiper 5 roves to connect with the separate segments successively so that the indicator lights indicate the degree of opening of the cock. Additionally, a segment 3.0 is provided at the "off" position, this segement being connected to an "off' indicator light.

In Figure 3, a third track is provided which is segmented at 6.1 and 6.2, each segment being connected to another supplementary device.

In gas appliances, a track or segment may be n nec.eò to a spark generator so that as the gas supply is turned on at a burner, the gas is ignited.

In sliding controls, the tracks or segments thereof are linear and parallel to the line of movement cf the knob of the control, the wiper being moveable with the knob so that in its traverse it can connect two or more parallel tracks or segments to provide substantial y the same supplementary switching functions as described above.

Claims (10)

.CLAUYIS:

1. An electrical control mechanism comprising a printed circuit board having an electrically conductive track thereon, and a control member movable in relation to the track and having an electrically conductive wiper for engagement therewith.

2. A mechanism according to Claim 1 wherein said wiper is movable out of engagement with said track.

3. A mechanism according to Claim 1 or Claim 2 wherein the member is rotatable and the track is an arc about the centre of rotation of the member.

4. A mechanism according to any preceding Claim wherein the track is discontinuous.

5. A mechanism according to any preceding Claim wherein the resistivity of said track is not uniform.

6. A mechanism according to any preceding Claim wherein several tracks are provided on said board.

7. A mechanism according to Claim 6 wherein said wiper is movable to make connection between the tracks.

8. A mechanism according to Claim 6 wherein several wipers are provided on said member.

9. A mechanism according to any preceding Claim further including a light mounted on said board for indicating the relative position of said member.

10. An electrical control mechanism substantially as described herein with reference to the accompanying drawings.