GB2374000A

GB2374000A - Obstruction sensor for movable furniture part

Info

Publication number: GB2374000A
Application number: GB0105820A
Authority: GB
Inventors: Robert Maidment
Original assignee: Mountway Ltd
Current assignee: Mountway Ltd
Priority date: 2001-03-09
Filing date: 2001-03-09
Publication date: 2002-10-09
Also published as: GB0105820D0

Abstract

A power actuated movable furniture part such as a pivoting pillow support 12 includes an electrically conducting member eg an aluminium plate 18 or copper strips (18', Fig 2) and a capacitance sensing circuit (19) which arrests operation of the actuator when a user's body part is sensed in the path of the moving part. The actuator 14 may be a linear motor. A circuit (20) with a remote handset (21) for the operating actuator may be used. Chair back rests, leg supports and beds are also referred to.

Description

AN ARTICLE OF FURNITURE This invention relates to an article of furniture having at least one power driven movable part.

It is common these days to provide articles of furniture with one or more

power driven movable parts. Such articles include chairs with power movable back , t rests and/or leg supports, beds and pillow supports and are more commonly found in hospitals and nursing homes but are also found in domestic homes.

The movable parts are commonly powered by linear actuators and many accidents have occurred trapping body parts of a user or carer.

It is known to make use of sensors to sense the presence of a body-part of a user or carer between two relatively movable parts of the article but these known sensors rely upon contact, and often on relatively firm contact, with the body part of the user or carer. This contact can and does cause pain to the user or carer.

The present invention seeks to overcome this drawback.

According to the present invention, there is provided an article of furniture having at least one power driven movable part, sensing means for sensing the

presence of a body part of a user or carer and means for arresting movement of the power driven part towards the body part of the user or carer in response to the sensing means, wherein the sensing means comprises an electrically conductive member supported by the power driven movable part and a capacitance sensing circuit electrically connected to the electrically conductive member.

Preferably, the sensing means is capable of sensing when the power driven movable part is in close proximity to and prior to contact with a body part of a user. Alternatively, the sensing means senses light contact with the body part to arrest movement of the power driven part towards the body part of the user or carer.

Other preferred and/or optional features of the invention are set forth in claims 3 to 9.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure I is a perspective view of one embodiment of an article of furniture according to the present invention, and Figure 2 is a block diagram of a circuit associated with the article of furniture shown in Figure 1.

Referring to the drawings, there is shown therein a pillow support 10 for use on a bed. The pillow support comprises a base 11 and a movable pillow supporting member 12 pivotably connected to the base 11 by hinges 13. The base 11 and pillow supporting member 12 are each of plate-like form.

An electrically operated linear actuator 14 is connected between the base 11 and the support member 12 for pivoting the member 12 relative to the base 11.

Apertures 15 and 16 are provided in the base 11 and support member 12, respectively, for accommodating the actuator 14 and two upstanding stops 17 are provided on the base 11 to limit downward movement of the support member 12 to avoid damage to the actuator 14.

An electrically conductive member, typically in the form of a metal sheet 18 (as shown in outline in Figure 1), is provided on the underside of the support member 12. The sheet 18 is typically of aluminium and may be perforated. Preferably, the sheet 18 extends over substantially the entire undersurface of the support member 12.

As an alternative to the sheet 18, the electrically conductive member could be in the t form of one or more metal strips and typically copper strips 18 (see Figure 2).

A capacitance sensing circuit 19 is connected to the metal sheet 18. The sensitivity of this circuit 19 may be variable and ideally is set to sense when the

support member 12 comes into close proximity to and prior to contact with a body part of a user or carer.

The pillow support 10 also comprises a control circuit 20 and a remote control handset 21 for operating the actuator 14.

The capacitance sensing circuit 19 detects the presence of a body part of a user or carer prior to the body part becoming trapped between the base 11 and the support member 12 and arrests movement of the support member 12 towards the base 11. Movement may be entirely arrested by de-energising the actuator 14 or the movement may be reversed by reversing the direction of movement of the actuator 14.

The embodiment described above is applied to an article of furniture in the form of a pillow support. It may be equally applied to any other article of furniture having a power movable part, such as a chair having a power operated back rest and/or leg support or to a bed.

Claims

CLAIMS 1. An article of furniture having at least one power driven movable part, sensing means for sensing the presence of a body part of a user or carer and means for arresting movement of the power driven part towards the body part of the user or carer in response to the sensing means, wherein the sensing means comprises an electrically conductive member supported by the power driven movable part and a capacitance sensing circuit electrically connected to the electrically conductive member.
2. An article of furniture as claimed in claim 1, wherein the sensing means is capable of sensing when the power movable part is in close proximity to and prior to contact with a body part of a user or a carer.
3. An article of furniture as claimed in claim 1 or claim 2, wherein the electrically conductive member is a metal sheet.
4. An article of furniture as claimed in claim 3, wherein the sheet is perforated.
5. An article of furniture as claimed in claim 1 or claim 2, wherein the electrically conductive member is in the form of one or more metal strips.
6. An article of furniture as claimed in any one of the preceding claims, wherein the power driven movable part is pivotable relative to another part of the article.
7. An article of furniture as claimed in any one of the preceding claims, further comprising an electrically operated linear actuator for moving the power driven movable part.
8. An article of furniture as claimed in any one of the preceding claims, in the form of a pillow support.
9. An article of furniture as claimed in claims 1 to 7, in the form of a chair.
10. An article of furniture as claimed in claims 1 to 7, in the form of a bed.
11. An article of furniture substantially as hereinbefore described with reference to the accompanying drawings.