GB2400494A

GB2400494A - Dimmer switch

Info

Publication number: GB2400494A
Application number: GB0308965A
Authority: GB
Inventors: Henry Horton
Original assignee: Get PLC
Current assignee: Get PLC
Priority date: 2003-04-10
Filing date: 2003-04-17
Publication date: 2004-10-13
Anticipated expiration: 2023-04-17
Also published as: GB0308965D0; GB0308334D0; GB2400494B

Abstract

An electrical switch with a contact housing consists of a resistive element 2 with an electrically conducting resistive track 4 and electrical contact means which are capable of being moved along the track. The electrical contact means are also capable of being moved out of contact with the resistive track. The switch further consists of user indication means attached to the contact housing. The indication means are capable of indicating when the electrical contact means are moved out of contact with the resistive track.

Description

ELECTRICAL SWITCHES

The present invention relates to electrical switches, particularly but not exclusively to electrical dimmer switches.

Electrical dimmer switches are well known in the art of electrical switchware. Typically a dimmer switch for a light comprises a mechanical switch together with a suitable mechanism to allow a resistance to be varied in order to vary the level of light emitted from a light bulb.

These known form of switches suffer from the drawback of being rather bulky which makes them unsuitable for use with modern thin and flat place switchware.

For an electrical switch to be mounted on a wall a recess must be made in the wall into which electrical wires running in the interior of the wall can be introduced for connection to the switch. The recess is fitted with a wiring box having a standard depth. The electrical switch has, on its rear face, a contact housing in which all of the electrical connections are made.

For the switch to be mounted on the wall, the switch is introduced such that the contact housing is received in the wiring box and the switch is fastened to the box by a suitable fixing means such as screws.

Due to the inherent bulkiness of known dimmer switches, they can only be accommodated in these standardised wiring boxes when the front plate of the switch is of a sufficient depth to allow a substantial portion of the depth of the switch mechanism to be to be accommodated within the depth of the front plate.

It is a general aim of the present invention to provide an electrical switch, such as a dimmer switch, having a thin or flat front plate which is capable of being accommodated in the standard wall mounted bracket.

Therefore, according to a first aspect of the present invention there is provided an electrical switch with a contact housing comprising a resistive element with an electrically conducting resistive track and electrical contact means which are capable of being moved along the track, 1413265-! 1 said electrical contact means being further capable of being moved out of contact with the resistive track, the switch further comprising user indication means attached to the contact housing, the indication means being capable of indicating when the electrical contact means are moved out of contact with the resistive track.

Preferably the user indication means also operates to indicate when the electrical contact means is moved into contact with the resistive track.

According to a second aspect of the present invention there is provided an electrical switch with a contact housing comprising a resistive element with an electrically conducting resistive track and electrical contact means, said track having an electrically isolated area, the switch further comprising user indication means attached to the contact housing, the indication means being capable of indicating when the electrical contact means are in contact with the electrically isolated area.

Advantageously, the switch of the present invention can be used with a thin or flat plate in a standard wall mounted wiring box as it does not require the presence of an additional mechanical switch. However, since it would be possible for a user to damage the switch when manipulating it from an on to off position, principally by over manipulation, the user indication means allow a user to know when the switch is in an on or off position. This positive indication also enables the user to be certain that they have turned of the e.g. lamp that the switch controls.

Ideally the resistive element is provided in the form of a potentiometer.

Preferably the user indication means acts to create an audible sound to indicate when the switch is moved from an on to off position or vice versa, i.e. - the electrical contact means being moved from contacting the electrically conducting resistive track (on position) to not being in contact with the track (off position) or being in contact with the electrically isolated area of the track (off position) and vice versa. This is preferable since a user is traditionally attuned to the idea that when a switch is moved from the on to the off position, a clicking sound is made due to the operation of a mechanical switch.

1413265-! 2 The audible sound could be made by an interaction between a member attached to a switch control and a separate limb attached to the contact housing when they act against each other.

This interaction may be defined by a force being applied by a user to the member when in contact with the limb, wherein the audible sound, such as a clicking sound, results from the applied force being greater than the frictional force between the member and limb, their being forced apart causing the sound. This would be advantageous as the contact housing could then act in the manner of a sounding board, thus amplifying the audible sound. The separate limb could be formed integrally with the contact housing.

To enhance the acoustic ability of the user indication means the separate limb and/or contact housing can be made from a suitable plastics material having the desired acoustic properties, materials possessing these properties may be said to be acoustically bright, examples of such materials include polycarbonates, a polycarbonate alloy, polyesters, nylon with a filler, such as a mineral or glass, ABS (acrylonitrile butadiene styrene) plastics; or ABS plastics alloy.

Ideally, where the user indication means are formed integrally with the contact housing, the separate limb is made from an acoustically bright material as described above.

However, where the user indication means are not formed integrally with the contact housing, the separate limb may be made from a suitable metal, providing that at least the part of contact housing to which the separate limb is attached is made from an acoustically bright material as described above. Examples of a suitable metal include a spring steel, a copper alloy such as a phosphor bronze or a beryllium copper.

Alternatively, the user indication means could act to create a different feel for a user when a switch control is operated. For instance, the operation of the switch to cause the electrical contact means to be brought out of communication with the electrically isolated area of the resistive track and into communication with the non-conducting position (i.e. from an off position to an on position) could be met with a change in physical force required to operate the switch. Preferably the specific change in force would result from a change in frictional force requiring the user to apply a greater amount of physical force to operate the switch when the electrical contact means are in communication with the conductive part of the resistive track.

1413265-! 3 Ideally the change in frictional force is provided by a detent protruding from the switch control which may be brought to bear against the surface such that the frictional force between them increases when the switch control is operated to bring the electrical contact means into communication with the conductive part of the resistive track. Preferably, this surface has a corrugated effect to allow the frictional force to be administered in an intermittent fashion to more readily communicate to the user that the electrical contact means are in communication with the conductive part of the resistive track. Indeed the corrugations on the surface may also be capable of emitting an audible sound as the detent is passed over each corrugation.

As a further alternative the user indication means may comprise a combination of both of the aforementioned means which are capable of acting in unison or separately to allow the user to determine when the electrical contact means is in communication with the conductive part of the resistive track or not.

The resistive element is preferably a potentiometer. However, the resistive element could alternatively comprise the application of the resistive track by any suitable means such as by printing or vapour/vacuum deposition for example, with or without the electrically isolated area, on to a suitable substrate, such as a ceramic or bonded electrically insulating material, examples of this bonded material include paper or glass fibre, the substrate being fixed by any appropriate means directly on to a circuit board. Alternatively, the resistive element could be printed directly on to the printed circuit board to which the other components of the switch are attached. The resistive element may be made from a metal film, a metal oxide or a carbon track. Additionally, the resistive track can be made from a resistive polymer, this polymer can be applied to the substrate or the printed circuit board in the form of an ink through a normal screen printing process.

Most preferably the dimmer switch of the present invention is a rotary dimmer switch. The rotary dimmer switch typically possesses a substantially circular electrically conductive resistive track. The mode of operation being the generally circular rotation of the potentiometer to cause a variation in the conductivity/resistance. Of course the track could 1413265-1 have an elliptical shape, or any other suitable shape which permits a similar rotational mode of operation.

Alternatively, the dimmer switch of the present invention may be a linear dimmer switch, commonly referred to as a slider dimmer switch. In this form of the dimmer switch, the switch control could be moveable along the track via a sliding movement and the user indication means could be located toward one extremity of the track for interaction with the member attached to the switch control. The contact housing can have a channel which accommodates the switch control, the channel may define a path which corresponds to the shape of the resistive element to permit the sliding movement therealong by the switch control. The channel and resistive element may have a substantially straight shape, alternatively they may be shaped in the form of a curve or an arc, as a further alternative they may have a spiral shape.

The switch control is formed by the insertion of a spindle into an aperture of the cover housing. The spindle has at its central axis a rod capable of engaging the resistive element to enable the operation thereof via a corresponding operation of the spindle. The spindle may be arranged to pass through an aperture in the circuit board in order to engage resistive element and enable the operation thereof.

The spindle can be formed with at least one projection. When the spindle is introduced into the contact housing, the at least one retaining protrusion is adapted to bear against the contact housing to assist the retention of the spindle in the housing. Ideally the at least one retaining protrusion is shaped to form a snap-fit connection with the contact housing.

The projection(s) may also be capable of acting as the member attached to the switch control and the detent respectively.

In one preferred embodiment of the control means, the spindle can be formed with at least one projection extending radially therefrom. The cover of the contact housing may be provided with an aperture to allow the spindle to pass there through, the aperture being surrounded on its exterior surface by a bushing extending perpendicularly away from the surface. The bushing can have a smooth interior surface to allow the spindle shaft to freely 41 3265-! 5 rotate, and have an exterior surface suitably configured to allow attachment of the switch to a switch plate, for example the exterior surface can be threaded to accept a nut. For the spindle and projection(s) to be introduced into the contact housing, the bushing may be provided with a slot extending down one side of the bushing, so that the bushing has a C-shape structure, as well as there being a corresponding slot in the contact housing cover. When the spindle is introduced into the bushing the slots define a passage along which the projection(s) can pass into the interior of the contact housing, until they are able to bear against the interior surface of the cover. To guard against the spindle being pushed too far into the switch, the spindle may have a radial flange which abuts the top edge of the bushing.

One drawback of the C-shape structure of the bushing is that when the switch is attached to the switch plate, by a nut for instance, the bushing can have a tendency to produce a clamping action on the spindle making it difficult to freely rotate under a user's control. To overcome this, a washer element with an aperture to accommodate the external dimensions of the bushing can be provided to pass over the bushing, the washer having a perpendicularly extending flange which has suitable dimensions to fill the slot in the bushing. The washer element's flange provides lateral support to the bushing and minimises or prevents any clamping action being imparted to the spindle.

In an alternatively preferred embodiment of the control means, the spindle can be formed from at least two separate components. The outer component of the spindle has a radial flange which is configured to abut the top edge of the bushing, which in this embodiment does not have a slot along its length, to ensure that the outer component can not be pushed too far into the of the switch. The outer component of the spindle has a portion which is sized to extend into the interior of the bushing and to overlap with a corresponding portion of an inner component of the spindle. The inner component is provided with the at least one projection extending radially therefrom.

The corresponding portions of the outer and inner components of the spindle can connected to each other by any suitable method: for example such as by adhesive; by welding, which is the case of the components being formed from plastics materials can be achieved by ultrasound; or by pinning, whereby a rigid pin is passed radially through the overlapping portions.

1413265-] 6 In order to avoid any contra-rotation of the overlapping portions of the spindle, said portions could both have a corresponding non-circular shape, such as a D-shape structure.

Whilst the above described preferred embodiments of the control means are suited for use in a switch of the present invention, it is also envisaged that they may have a wider application beyond switches and dimmer switches.

According to a third aspect of the present invention there is provided an electrical dimmer switch with a contact housing comprising a resistive element with an electrically conducting resistive track and electrical contact means which are capable of being moved along the track, said electrical contact means being further capable of being moved out of contact with the resistive track, wherein the contact housing has a depth of less than 2cm. Preferably the I contact housing has a depth of less than 1.65cm, and most preferably less than 1.5cm. A preferred embodiment of the switch further comprises user indication means attached to the contact housing, the indication means being capable of indicating when the electrical contact means are moved out of contact with the resistive track I In order that the present invention can be more readily understood a specific embodiment thereof is described below with reference to the drawings by example only.

Fig. 1 shows a plan view of a potentiometer of the present invention; ; Fig. 2 shows a plan of view of the switch of the present invention; Fig. 3 shows a prospective view of a spindle and cover of the contact housing; and Fig. 4 illustrates a side elevation of a spindle with the cover of the contact housing.

Fig. 1 shows a plan view of a resistive element in the form of potentiometer 2. The components of the potentiometer 2 include a resistive track which is separated into an electrically isolated area 6 and an electrically conductive part 8. At the centre of the potentiometer 2 is the rod 10 of the spindle 12 also at the centre of the potentiometer 2 is a radially extending member 14.

1413265-! 7 The potentiometer 2 as shown in Fig. 1 is in an off position by virtue of an electrical conductive means being in communication with the isolated area 6 of the track 4. The tip 16 of the member 14 bears against the tip of the limb 18.

In order to manoeuvre the switch as shown in Fig. 1 from the off position to the on position, the frictional force between the tip 16 and the limb 18 must be overcome. To achieve this the user applies sufficient rotational force to the spindle 12 which is transferred to the rod 10. As the rotational force is increased the pressure of the tip 16 of the member 14 on the limb 18 causes the limb to distend from its normal position. During continued application of the rotational force, there comes a point when the frictional force between the tip 16 and limb 18 is overcome allowing the member 14 to move away from the limb 18. As the limb 18 has been forced out of its normal position during the application of the rotational force, it snaps back into its original position and, due to its integration or attachment with the contact I housing, causes audible sound in the form of a click. The acoustic nature of the contact housing enhances this sound as the housing may act as a sounding board, and the limb 18 may act as a tuning fork having the effect of amplifying the sound made.

The potentiometer also has at its centre a detent 20 extending readily therefrom. Once the member 14 has been moved away from the limb 18, the tip of the detent 20 is capable of frictionally bearing against a corrugated surface 22 as the user continues to apply rotational force to the spindle 12, the detent 20 moves against the tips of the corrugated surface 22 causing the user to apply an increased amount of rotational force in order to urge the; electrical conductive means (not shown) towards the conductive part 8 of the resistive track 4. The increased resistive force required allows the user to appreciate that the member 14 is being rotated away from the limb 18 and, thus, the switch is being moved from an off to an on position.

Fig. 2 shows the potentiometer shown in Fig. 1 when mounted in the cover of 24 of the contact housing. The cover 24 is provided with a series of catches which can be used to receive corresponding clips 28 mounted on the base (not shown) of the contact housing.

Turning now to Figs. 3 and 4 it can be seen that the front plate 30 of the contact housing has a central aperture sized to receive the spindle 12. For ease of assembly the spindle has, 1413265-1 8 positioned towards the lower end thereof, a pair of retaining legs 32 which protruded perpendicularly from the axle of the spindle 12. When the spindle 12 is introduced into the aperture in the cover 24, the retaining legs 32 are able to snap into engagement with cover 24 to retain the spindle in engagement therewith. When the spindle 12 is so engaged, the rod 10 engages the potentiometer to allow the user to control the switch via rotational manipulation ofthespindle12.

As will be apparent to those skilled in the art, numerous modifications and variations can be made to the embodiments specifically described herein without departing from the invention.

For instance, the retaining legs may also be capable of acting as the member 14 and the detent respectively. Additionally, although the use of the dimmer switch described relates to rotary dimmer switches, the internal configuration of the switch can be adjusted to make it applicable to linear dimmer switches. Furthermore, the user indication means could take the form of additionally providing a visual indicator to the user which is capable of changing colour depending on the position of the switch, or a visual means such as an LED to become illuminated depending on the position.

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Claims

Claims 1. An electrical switch with a contact housing comprising a

resistive element with an electrically conducting resistive track and electrical contact means which are capable of being moved along the track, said electrical contact means being further capable of being moved out of contact with the resistive track, the switch further comprising user indication means attached to the contact housing, the indication means being capable of indicating when the electrical contact means are moved out of contact with the resistive track.
2. The electrical switch according to claim 1, wherein the user indication means also operates to indicate when the electrical contact means is moved into contact with the resistive track.
3. An electrical switch with a contact housing comprising a resistive element with an electrically conducting resistive track and electrical contact means, said track having an electrically isolated area, the switch further comprising user indication means attached to the contact housing, the indication means being capable of indicating when the electrical contact means are in contact with the electrically isolated area.
4. The electrical switch according to any preceding claim, wherein the resistive element is provided in the form of a potentiometer.
5. The electrical switch according to any preceding claim, wherein the user indication means acts to create an audible sound to indicate when the switch is moved from an on to off position or vice versa.
6. The electrical switch according to claim 5, wherein the audible sound is made by an interaction between a member attached to a switch control and a separate limb attached to the contact housing when they act against each other.
7. The electrical switch according to claim 5 or claim 6, wherein the contact housing acts as a sounding board.
8. The electrical switch according to at least one of claims 5 to 7, wherein the separate limb is formed integrally with the contact housing.

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9. The electrical switch according to any preceding claim, wherein the separate limb and/or contact housing is made from a suitable plastics material having the desired acoustic properties, materials possessing these properties may be said to be acoustically bright, examples of such materials include polycarbonates, a polycarbonate alloy, polyesters, nylon with a filler, such as a mineral or glass, ABS (acrylonitrile butadiene styrene) plastics; or ABS plastics alloy.
10. The electrical switch according to any preceding claim, wherein the user indication means are formed integrally with the contact housing.
11. The electrical switch according to any of claims 1 to 9, wherein the separate limb is made from metal.
12. The electrical switch according to claims 11, wherein the separate limb is made from at least one of the metals from the group of: spring steel; copper alloy; phosphor bronze; beryllium copper.
13. The electrical switch according to any preceding claim, wherein the user indication means is configured to require a user to apply a greater amount of physical force to operate the switch when the electrical contact means are in communication with the conductive part of the resistive track.
14. The electrical switch according to claim 13, wherein the change in force is provided I by a detent protruding from the switch control which is brought to bear against a surface. ;
15. The electrical switch according to claim 14, wherein the surface is provided with a corrugated effect to allow the force to be administered in an intermittent fashion.
16. The electrical switch according to claim 15, wherein the corrugations on the surface are adapted to emit an audible sound as the detent is passed over each corrugation.
17. The electrical switch according to any preceding claim excluding claim 4 or any claim when dependent thereon, wherein the resistive element comprises the application of the resistive track on to a suitable substrate. I 1509401-1 1 1
18. The electrical switch according to claim 17, wherein the application of the resistive track involves printing or vapour/vacuum deposition.
19. The electrical switch according to claim 17 or claim 18, wherein the substrate is a ceramic or a bonded electrically insulating material.
20. The electrical switch according to claim 17, wherein the resistive element is printed directly on to the printed circuit board to which the other components of the switch are attached.
21. The electrical switch according to any of claims 17 to 20, wherein the resistive element is made from at least one of: a metal film; a metal oxide; a carbon track; a resistive polymer.
22. The electrical switch according to any preceding claim, wherein the switch is a rotary dimmer switch. 5
23. The electrical switch according to claim 22, wherein the mode of operation of the switch is a substantially circular rotation to cause a variation in the conductivity/resistance.
24. The electrical switch according to claim 22, wherein the resistive track has an elliptical shape to permit a rotational mode of operation.
25. The electrical switch according to any of claims 1 to 21, wherein the switch is a linear dimmer switch.
26. The electrical switch according to claim 25, the switch control is moveable along the track via a sliding movement and the user indication means are located toward one extremity of the track for interaction with the member attached to the switch control.
27. The electrical switch according to any preceding claim, wherein the switch control is formed by the insertion of a spindle into an aperture of the cover housing.
28. The electrical switch according to claim 27, wherein the spindle has at its central axis a rod capable of engaging the resistive element to enable the operation thereof via a corresponding operation of the spindle.

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29. The electrical switch according to any preceding claim, wherein the spindle can be formed with at least one projection.
30. The electrical switch according to claim 29, whereby the spindle is introduced into the contact housing and at least one retaining protrusion is provided where said protrusion is adapted to bear against the contact housing to assist the retention of the spindle in the housing.
31. The electrical switch according to claims 29 or 30, wherein the projection(s) is capable of acting as the member attached to the switch control and the detent respectively.
32. The electrical switch according to any of claims 27 to 31, wherein the cover of the contact housing is provided with an aperture to allow the spindle to pass therethrough, the aperture being surrounded on its exterior surface by a bushing extending perpendicularly away from the surface. ;
33. The electrical switch according to claim 32, wherein the bushing has a smooth interior surface to allow the spindle shaft to freely rotate, and has an exterior surface suitably configured to allow attachment of the switch to a switch plate.
34. The electrical switch according to claim 32 or 30, wherein the bushing is provided with a slot extending down one side of the bushing, so that the bushing has a C-shape structure, as well as there being a corresponding slot in the contact housing cover.
35. The electrical switch according to any of claims 32 or 34, wherein a washer element is provided having an aperture to accommodate the external dimensions of the bushing, the I washer having a perpendicularly extending flange of suitable dimensions to fill the slot in the bushing. ;
36. The electrical switch according to any of claims 27 to 35, wherein the spindle is formed from at least two separate components.
37. The electrical switch according to claim 36, wherein the outer component of the spindle has a radial flange which is configured to abut the top edge of the bushing.

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38. The electrical switch according to claim 36 or 37, wherein the outer component of the spindle has a portion which is sized to extend into the interior of the bushing and to overlap with a corresponding portion of an inner component of the spindle, whereby the inner component is provided with the at least one projection extending radially therefrom.
39. The electrical switch according to any of claims 36 to 38, wherein contra-rotation of the overlapping portions of the spindle is avoided, whereby said portions both have a corresponding non-circular shape.
40. An electrical dimmer switch with a contact housing comprising a resistive element with an electrically conducting resistive track and electrical contact means which are capable of being moved along the track, said electrical contact means being further capable of being moved out of contact with the resistive track, wherein the contact housing has a depth of less than 2cm.
41. The electrical dimmer switch according to claim 40, wherein the contact housing has a depth of less than 1.65cm.
42. The electrical dimmer switch according to claim 40, wherein the contact housing has a depth of less than 1.5cm.
43. The electrical dimmer switch according to any of claims 40 to 42, wherein the switch further comprises user indication means attached to the contact housing, the indication means being capable of indicating when the electrical contact means are moved out of contact with the resistive track.

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