GB2289165A

GB2289165A - Dimmer switch

Info

Publication number: GB2289165A
Application number: GB9408137A
Authority: GB
Inventors: David Andrew Deeming; Stephen James Maddern
Original assignee: HOME AUTOMATION Ltd
Current assignee: HOME AUTOMATION Ltd
Priority date: 1994-04-25
Filing date: 1994-04-25
Publication date: 1995-11-08
Also published as: GB9408137D0

Abstract

A combined dimmer and on/off switch is disclosed. A common spindle 24 is depressible against a spring 34 to operate the switch 2 and is rotatable to operate a rheostat 4 to control the dimmer. An end portion of the spindle has a flat 46 to locate a control knob. A wiper 56 engages a track 48 which is formed with spaced indentations. The spindle thus rotates in a series of steps with respective clicks improving the feel of rotation to a user. <IMAGE>

Description

DINNER This invention relates to dimmers used, for example, for household lighting circuits and, when an on/off switch is present, commonly referred to as "dimmer switches".

The present invention is based on the recognition of a previously unidentified problem. Existing dimmers on the British market have what we perceive to be a very poor quality feel in operation. One aspect of the problem is caused by the dimmer having a knob, rotation of which controls the level of illumination. In general the knob is attached to the spindle of a rheostat and the size of the knob combined with the low frictional forces required to rotate the spindle makes it feel as if the knob is not connected to anything. Especially with dimmer switches in which pressing the same knob operates an on/off switch, the spindle is round in section, the knob being merely pressed on the spindle. When the rheostat is at the end of its travel, the knob can be turned further.This contributes a poor quality feel in its own right but also adds to sensation that the knob is not connected to anything.

Against this background, in accordance with one aspect of the invention, there is provided a combined dimmer and on/off switch, wherein a common spindle is depressible against a bias to operate the switch and rotatable to operate a rheostat to control an out put of the dimmer, an end portion of the spindle having a flat to locate a control knob. The flat prevents the knob from being rotated beyond the position at which the rheostat has reached the end of its travel greatly improving the feel.

In accordance with another aspect of the invention there is provided a lighting dimmer, including a rheostat having a spindle rotatable to control the output of the dimmer, including first means rotatable with the spindle and engaging stationary second means separate from the resistive track of the rheostat, to increase resistance to rotation of the spindle. This provides the user an improved perception that the knob is connected thus, again, improving the feel.

In a most preferred form, one of the first and second means comprises a wiper resiliently engaging a track on the second means, a series of recesses, depressions or undulations being spaced around the track so that movement of the spindle assumes a series of steps. Although there may be an apparent disadvantage in this arrangement, in that the output of the dimmer is not infinitely variable, the improvement in feel more than compensates, and we have found that the recesses, depressions or undulations may be sufficiently closely spaced that there is no practical disadvantage in the obtainable output variations.

Very preferably, both aspects of the invention are provided, a common spindle being depressible against a bias to operate the switch and rotatable to operate the rheostat to control the dimmer, an end portion of the spindle having a flat to locate a control knob.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross section through a part of a dimmer switch embodying the invention; Figure 2 is a plan view of the dimmer switch of Figure 2 with its cover removed; Figure 3 is an elevation of a component of the dimmer switch of Figure 1; Figure 4 is a plan view of a component which cooperates with the component of Figure 3; and Figure 5 is a circuit diagram of the dimmer switch.

Referring to the drawings, Figure 1 shows an on/off switch 2 and a rheostat 4 which are operated by a common spindle 6. The on/off switch 2 is used to control whether or not lights (not shown) are on or off. The rheostat 4 is used to control the output of a conventional dimmer 8 (see Figure 5).

The spindle 6 which projects from a hole 20 in a housing or cover 22 is rotatable and slidable longitudinally therein. The spindle 6 has a rectangular section end portion 24 which is extends into and is slidable longitudinally in one end of a hole 26 through a rotor 28.

A press button 30 of the switch 2 extends into the hole 26 from its other end so that depression of the spindle 6 in the direction of arrow "A" will operate the switch. The switch is of the push-push type so that consecutive depressions of the spindle open and close the switch contacts (not shown).

The spindle has a flange 32 to limit its outward movement from the hole 22 and a spring 34 acts between the collar and the rotor to bias the spindle outwardly.

Sandwiched between the switch 2 and the cover 22 is an insulating carrier on which are printed resistive tracks (not shown). Conductive wipers 36, 38 and 40 are mounted on the rotor 28 for rotation therewith and contact the tracks slidingly so as to provide a conventional rheostat function between three terminals one of which is shown at 40. The rheostat is shown at PP1 in Figure 5 and functions to control the firing angle of a triac TC1 via a diac DC1. The triac TC1 in series with a toroidal winding TCL1 controls the current drawn by a lamp, as is conventional, so as to control the brightness of the lamp.

The hole 26 is rectangular in section to match the rectangular section of the end portion 24 so that rotation of the spindle 6 drives the rotor to rotate and thus slides the wipers on their tracks.

A lug 42 extends from the periphery of the rotor 28 and engages a stop (not shown) which projects inside the cover 22 to limit the rotational movement of the spindle.

In order that the knob (not shown) to be fitted to the spindle shall not rotate further when the spindle has reached the limit of its movement defined by the lug and its stop member, that part 44 of the spindle 6 which projects from the cover 22, is provided with a flat 46. The knob (not shown) has a D-shaped recess to receive the spindle.

That in itself improves the feel of the dimmer switch to the operator. The embodiment illustrated includes a further improvement to the feel. A track 48 is fixed on the underside of the cover 22 over the rotor 28.

The rotor 28 caries a brass ring shaped wiper 50 fixed on its upper surface. The wiper 50 is creased at 52 raising one side above the rotor 28. This biases a button on a lug 56 resiliently into engagement with the track 48.

Engagement between the button 54 and the track 48 is designed to increase the frictional resistance to rotation of the spindle thus improving the feel. For this purpose, the track 50 illustrated is formed with spaced indentations 58. These cause the spindle to rotate in a series of steps with respective clicks. In other arrangements the indentations could be replaced with recesses or undulations.

Claims

1. A combined dimmer and on/off switch, wherein a common spindle is depressible against a bias to operate the switch and rotatable to operate a rheostat to control the dimmer, an end portion of the spindle having a flat to locate a control knob.

2. A lighting dimmer, including a rheostat having a spindle rotatable to control the output of the dimmer, including first means rotatable with the spindle and engaging stationary second means separate from the resistive track of the rheostat, to increase resistance to rotation of the spindle.

3. A dimmer as claimed in claim 2, wherein one of the first and second means comprises a wiper resiliently engaging a track on the second means, a series of recesses, depressions or undulations being spaced around the track so that movement of the spindle assumes a series of steps.

4. A dimmer as claimed in claim 2 or 3, wherein a common spindle is depressible against a bias to operate the switch and rotatable to operate the rheostat to control the dimmer, an end portion of the spindle having a flat to locate a control knob.