AU2001100358A4

AU2001100358A4 - Chair back improvements

Info

Publication number: AU2001100358A4
Application number: AU2001100358A
Authority: AU
Inventors: Justin Peter Brown
Original assignee: Klasse Pty Ltd
Current assignee: Klasse Pty Ltd
Priority date: 2001-09-10
Filing date: 2001-09-10
Publication date: 2001-10-11
Anticipated expiration: 2009-09-10
Also published as: AU2001100358B4

Description

531891P HKS:ZS PI/00/002

AUSTRALIA

Patents Act 1990

ORIGINAL

INNOVATION PATENT SPECIFICATION FOR AN INVENTION

ENTITLED

Invention Title: CHAIR BACK IMPROVEMENTS Name of Applicant: KLASSE PTY LTD Address for Service: COLLISON CO. 117 King William Street, Adelaide, S.A. 5000 The invention is described in the following statement: This invention relates to a chair back and, in particular, to an arrangement providing for control of a chair back with respect to a base.

The problem to which this invention is directed relates to chairs of a type that have a back rest which can be adjustable in height.

Such adjustment in height is achieved by having a stem supporting the back which then is adjustably supported with respect to a base.

Some various mechanisms are known to provide for control of the position of the back rest but the problem is to provide a mechanism which is both effective and 1 0 which can be very economically manufactured.

In one form of this invention, although it need not necessarily be the only or indeed the broadest form of this, there is provided a chair back including a stem for supporting a back rest, and a base supported by the stem so as to be able to be raised and lowered with respect to the stem, and support means to enable the retention of the stem at a selected height with respect to the base which support beams include a ratchet secured to one of the stem or back rest and a pawl connected to the other of the stem or back rest, where the ratchet includes a nonratchet return track for the pawl and is arranged so that the pull at one end of the ratchet is biased to enter the return track, and at an opposite end of the track is biased to engage back into the ratchet.

In preference, the pawl is resiliently supported so that it will resiliently engage with respect to the ratchet and that the bias at respective ends of the ratchet are achieved by the position of the resilient retention of the pawl.

In preference, there are two ratchets and two non-ratchet return tracks for a pawl located one to each side of a pawl.

In a further form, the invention can be said to reside in a chair which includes a chair back as described.

For a better understanding of this invention it will now be described with the assistance of drawings wherein: FIG. 1 is a side view showing an assembly according to the embodiment of this invention; FIG. 2 is a perspective view of the resiliently held pawl and one rack of the embodiment; FIGS. 3, 4 and 5 are sequential views of the pawl with respect to the ratchet or non-ratchet return track in various stages of operation; and FIG. 6 is a perspective view of the assembly of the embodiment.

Now referring in detail to the drawings, there is a base 1 which holds together two portions 2 and 3 which have on each side a shape formed from moulded plastics where there is a ratchet on one side shown at 5 and a non-ratchet return track at 6.

There is a stem 7 which is intended to support, at its upper end, a back rest for a chair and which is adjustably positionable therefore with respect to the base 1.

Secured to the stem 7 is a pawl 8 which includes a leg 9 and an operating head The operating head 10 is supported by the leg 9 so as to be resiliently displaceable but to be retained in a resting position which would normally position the head somewhat between the ratchet track 5 and the non-ratchet track 6.

With this arrangement then, as is particularly shown in FIGS. 3 through 5, by variously positioning the stem 7 and therefore the pawl with its associated resiliently held head 10, the pawl will effect an interlocking engagement with the ratchets so that the stem 7, when the pawl is interengaging with the ratchet, will only be able to be moved in one direction and will interlock if pushed against this direction.

However, a continuation of this action will eventually locate the head 10 at an end 14 of the ratchet track where there is an opening so that the bias of the head 10 will drop this so that it will be caught by the inclined face 15 of the non-ratchet track 6.

From here, the stem 7 can be then moved so that the pawl can be returned fully to a starting location which is at the other end of the non-ratchet track 6 and where there is a slight diversion 8 in the shape of the track so that once the pawl 10 is past this point, it will bias so as to be captured on the inclined plane 17 and then revert into the ratchet track.

This then shows how the apparatus can be made to provide a very effective nonreturn positioning of a back rest except when the back rest is moved into an extreme position and then returned to pass through the track once again.

The invention can, of course, apply to a chair incorporating this mechanism as well as to a mechanism for use with a chair and, as well, a mechanism in which a seat back is also secured to a stem supported by the mechanism.

While in the specific description, the pawl is supported directly by the stem, it will be appreciated that this can be reversed so that the ratchet track and non-ratchet return track can be directly positioned with respect to the stem and the pawl can be supported resiliently by the base.

These and other changes are all considered to be included within the invention.

Claims

1. A chair back including a stem for supporting a back rest, and a base supported by the stem so as to be able to be raised and lowered with respect to the stem, and support means to enable the retention of the stem at a selected height with respect to the base which support means includes a ratchet secured to a one of the stem or back rest and a pawl connected to the other of the stem or back rest, where the ratchet includes a non-ratchet return track for the pawl and is arranged so that the pawl at one end of the ratchet is biased to enter the return track, and at an opposite end of the track is biased to engage back into the ratchet.

2. A chair back including a stem for supporting a back rest, and a base supported by the stem so as to be able to be raised and lowered with respect to the stem, and support means to enable the retention of the stem at a selected height with respect to the base which support means include a ratchet secured to a one of the stem or back rest and a pawl connected to the other of the stem or back rest, the pawl or its support being so as to be resiliently movable and where the ratchet includes a non-ratchet return track for the pawl and is arranged so that the pawl, when in a position at one end of the ratchet is biased to enter the return track, and when in an opposite end of the track is biased to engage back into the ratchet.

3. A chair including a chair back including a stem for supporting a back rest, and a base supported by the stem so as to be able to be raised and lowered with respect to the stem, and means to enable the retention of the stem at a selected height with respect to the base which means include a ratchet secured to a one of the stem or back rest and a pawl connected to the other of the stem or back rest, where the ratchet includes a non-ratchet return track for the pawl and is arranged so that the pawl at one end of the ratchet is biased to enter the return track, and at an opposite end of the track is biased to engage back into the ratchet. Datedthis 1 0h day of September 2001 KLASSE PTY LTD By their Patent Attorneys COLLISON CO