GB2153665A

GB2153665A - Chair with adjustable backrest

Info

Publication number: GB2153665A
Application number: GB8501238A
Authority: GB
Inventors: Graham Marshall Pickles
Original assignee: SHACKLETONS
Current assignee: SHACKLETONS
Priority date: 1984-01-20
Filing date: 1985-01-18
Publication date: 1985-08-29
Also published as: GB8501238D0

Abstract

An adjustable chair is provided having means operable to permit planar rotary movement of the backrest, the means comprising a helical gear (10) which is in mesh with a spur gear (11) fixed to an elongate shaft (12) which extends through a leg (3) of the chair and is keyed to a rotatable disc (13) received within a complementary recess (14) at the lower end of each side of the backrest (5) of the chair. Rotation of the helical gear (10) by means of a hand wheel (6) induces rotation of the spur gear and shaft, which is keyed off centre to each disc to provide the necessary eccentric planar rotary movement. The chair seat is also adjustable (Fig. 3). <IMAGE>

Description

SPECIFICATION Adjustable Chair This invention relates to a chair in which the positions of the backrest and chair seat can be adjusted.

According to the invention there is provided a chair incorporating a chair frame, a backrest and a chair seat, the chair having means operable to permit planar rotary movement of the backrest in any direction.

Conveniently, the chair is also provided with a movable chair seat incorporating means operable to permit the seat to be axially movable along a plane coincident with the plane along which the backrest is movable, the chair also having means adapted to releasably secure the seat to the chair.

The means operable to permit planar rotary movement of the backrest in any direction may conveniently comprise a helical gear and a spur gear assembly fixed to a leg adjacent the lower end of the backrest and being co-operable with the rear of the chair frame such that clockwise or anticlockwise rotation of the helical gear induces rotary movement of the spur gear and hence the backrest in any direction.

The chair seat may be releasably secured to the chair frame by a pair of guide tracks, one on each side of the chair frame, and a pair of complementary pegs on the seat which are engagable with the tracks to permit sliding movement of the seat therealong. The seat may also be provided with a pair of studs which slot into shaped recesses on the chair such that the seat can be secured in a number of different positions.

Conveniently, the seat may be in cross-section substantially tapered and instead of a pair of pegs, there may be provided two pairs of pegs, each pair of pegs being lotated at opposite ends of the seat with respect to the other pair of pegs, the arrangement being such that in addition to the seat being axially adjustable along the chair, it may also be rotated through 1800 to permit the inclination thereof to be adjusted, depending upon whether the seat tapers away from or towards the backrest.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side elevation of a chair according to the invention, Figure 2 is a view of part of the chair of Figure 1 showing schematically the mode of operation of the back rest.

Figure 3 is a further schematic view of part of the chair of Figure 1 showing the mode of operation of the chair seat.

Referring firstly to Figure 1, there is shown a side elevation of a chair which comprises an elongate arm rest 1, from respective ends of which depend a front leg 2 and the rear leg 3, between which is fixed the side rail 4. The opposite side of the chair is symmetrical and is conventionally fixed to the side of the chair shown in the drawing by front rail between each of the front legs 2 adjacent the side rail 4 and a rear rail between each of the rear legs 3 adjacent the side rail 4 also. The construction of the chair thus far described is entirely conventional and defines a chair frame according to the invention.

Extending upwardly from the upper end of the rear leg 3 is an elongate backrest 5 which is capable of planar movement in any direction, as indicated by the arrows at the top of the backrest 5, through operation of a hand wheel 6 fixed to one side of the chair frame on the leg 3 thereof. The mode of operation of the hand wheel 6 will be described subsequently with reference to Figure 2.

Fixed to the backrest 5 between each of the rear legs 3 above the hand wheel 6 are a pair of pivot pins 7 which extend into complementary elongate slots 8 (shown in Figure 2) on each side of the lower part of backrest 5. The backrest 5 is thus pivotable and slidable about the axis of each pivot pin 7 when the hand wheel 6 is rotated in a clockwise or anti-clockwise direction as shown.

Between each side of the chair frame above each hand rail 4 is secured a chair seat 9 which is capable of axial movement in the direction of the arrows shown along the upper surface of the side rail 4. Operation of the sliding mechanism of the chair seat will be described later, with reference to Figure 3 of the accompanying drawings.

Referring now to Figure 2 of the drawings, there is shown the lower part of the backrest 5, the upper part of the rear leg 3 and a respective end portion of the arm rest 1. It will be seen that the hand wheel 6 is rotatably connected to a helical gear 10 which is in mesh with a spur gear 11 fixed to an elongate shaft 12. The shaft 12 extends through the leg 3 and is keyed to a rotatable disc 13 received within a complementary recess 14 at the lower end of each side of the backrest 5. Accordingly, rotation of the hand wheel 6 and hence helical gear 10 induces rotation of the spur gear 11 and shaft 12. Because the shaft 12 is keyed off centre to each disc 13 on each side of the backrest 5 eccentric movement of the backrest 5 is afforded in any direction in a plane perpendicular to the shaft 13.

Each pivot pin 7 and complementary slot 8 on each side of the chair ensures that the eccentric rotary movement afforded by the gear means is satisfactorily limited.

Turning now to Figure 3, there is shown part of the front leg 2, side rail 4 and the chair seat 9. At the front and rear of the base of the seat are fixed two pairs of horizontally opposed pivot pins 15a and 15b fixed to lugs 16a and 16b such that they can be slid in turn into a guide track 17. On the top of each rail 4 there is provided a number of recesses 18, which can receive in turn a boss 19 fixed to each side of the seat 9, by which the seat 9 can be secured in any desired position. Although the seat 9 is thus axially movable along side rail 4, it will be apparent that if the front of the seat 9 is lifted and the rear pair of pins 15a are disengaged from the guide track 17, the seat can be rotated through 1800 such that the other set of pins 15b can be received in the guide track 17. The seat 9 has a tapered cross-section and thus it is possible to alter the inclination of the seats such that it may taper towards or away from the backrest.

Claims

1. A chair incorporating a chair frame, a backrest and a chair seat, the chair having means operable to permit planar rotary movement of the backrest in any direction.

2. A chair according to claim 1 in which the means operable to permit rotary movement of the backrest comprises a helical gear and a spur gear assembly fixed to a leg adjacent the lower end of the backrest and being co-operable with the rear of the chair frame such that clockwise or anti-clockwise rotation of the helical gear induces rotary movement of the spur gear and hence the backrest in any direction.

3. A chair according to claim 2 in which the spur gear is mounted on a shaft keyed off-centre to a disc received in a recess on either side of the back rest such that rotation of the shaft can afford eccentric planar rotary movement.

4. A chair according to any preceding claim in which the backrest is provided with pivot pins which extend into complementary slots in the chair frame adjacent the gear assembly, the pins having their major axis parallel to the rotational axis of the spur gear, such that when the spur gear is rotated in either direction, planar movement of the backrest is limited to the range of movement afforded by the pivot pins in the slots.

5. A chair according to any preceding claim incorporating means operable to permit the seat to be axially movable along a plane coincident with the plane along which the backrest is movable.

6. A chair according to claim 5 in which the seat also incorporates means adapted to releasably secure it to the chair.

7. A chair according to claim 5 or claim 6 in which the seat is releasably securable to the chair frame by a pair of guide tracks, one on each side of the chair frame, and complementary pegs on the seat which are engagable with the tracks to permit a sliding movement of the seat thereon.

8. A chair according to claim 7 in which the seat is provided with a pair of studs which slot into shaped recesses on the chair such that the seat can be secured in a number of different positions.

9. A chair according to any preceding claim in which the seat is substantially tapered.

10. A chair according to claim 7, 8 or 9 having two pairs of pegs, each pair of pegs located at opposite ends of the seat, the arrangement being such that in addition to the seat being axially adjustable along the chair, it may also be rotated through 180 to permit the inclination thereof to be adjusted, depending upon whether the seat tapers away from or towards the backrest.

11. A chair substantially as hereinbefore described with reference to and as shown in the accompanying drawings.