AU715954B2 - Latch mechanism to control height adjustment of various seat components - Google Patents

Description

Regulation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

9**e Name of Applicant: Actual Inventors: Address for Service: Invention title: Workspace Commercial Furniture Pty Ltd Maxwell Dickison Tony Damien Kearney MADDERNS, 1st Floor, 64 Hindmarsh Square, Adelaide, South Australia, Australia LATCH MECHANISM TO CONTROL HEIGHT ADJUSTMENT OF VARIOUS SEAT COMPONENTS Details of Associated Provisional Application No: PO 3007 filed 15th October 1996.

The following statement is a full description of this invention, including the best method of performing it known to us.

This specification describes several design features which are improvements in relation to the design and operation of a chair, but relates specifically to a latch mechanism used to control height adjustment of various seat components.

A means of conveniently adjusting the height of the back and arm rests is described.

In known back and arm rest height adjustment means, it is normal to provide a clamp which operates via a screw thread knob or cam actuated lever. These are normally situated adjacent to the seat where the back and arm rest support tubes are joined to the seat frame.

Described in the specification is a means which allows for convenient back and arm rest height control which is located in a position which is much easier to reach.

Another feature described is a connection arrangement between metal arm rest and 15 back rest tubes.

44.4 It is broadest form, the invention is a latch mechanism for controlling height adjustment of the back rest of a chair comprising: a back rest sleeve that is secured to the back rest of a seat with an open end 20 a back rest tube, for supporting the back rest above a seat, that slidably locates within the back rest sleeve through the open end, a latching mechanism that allows height adjustment of the back rest with respect to the back rest tube, and actuating means for the latching mechanism that is located below and adjacent the open end of the back rest sleeve.

Preferably, the actuating means moves along an axis which is parallel to the axis of the back rest tube. It may comprise a sleeve or collar that locates around the back rest tube which has appropriate flanges for manually operating the actuator. The actuator described may work in conjunction with a second method of releasing the latching mechanism. The actuating means may be operated by either pulling down or pushing up.

This specification also describes a back rest and arm rest sleeve retainer assembly comprising: an arm rest or back rest sleeve, an arm rest or back rest tube that locates within the respective sleeve; and a tube end fitting that is located in the end of the arm rest or back rest tube that acts to restrain or prevent movement of the arm rest or back rest sleeve with respect to the arm rest or back rest tube that might otherwise result from clearance between the two.

Any clearance between the respective tubes and sleeves will result in movement about two axes which are both normal to the longitudinal axis of the tube.

*I Accordingly, the fitting is required to restrain movement in both of these axes. In the case of a non-circular tube, such as a flattened tube, there can be no relative rotation 15 between the tube and the sleeve. Preferably, the tube end fitting comprises a body which locates within the end of the tube which has a pair of flexible arms that extend beyond the width of the tube at the top of the body and a second pair of flexible projections that extend at 90' with respect to the arms, both the arms and projections being designed to engage the inner surface of the sleeve to thereby hold the sleeve 20 firmly with respect to the tube. Both sets of arms are resilient, and therefore this resilience will allow for variation in clearance between the two components. The oooo resilient nature will also ensure that the two components can readily slide with respect to one another without having a loose feel that would otherwise result without the end fitting being in place.

In a further aspect of the retainer assembly, a locking arrangement may be used to prevent the arm rest or back rest sleeve from fully disengaging from the respective tube when the arm rest or back rest is pulled upwardly. Such an arrangement must enable easy assembly and disassembly while at the same time preventing the arm rest or back rest sleeve from fully disengaging in normal use.

In order to improve the tactile feel when grasping various portions of the seat, particularly where one of the surfaces being touched may be a smooth or semi-rough plastic moulding, it is proposed to make use of a softened piece of insert material that may be strategically placed on the respective surface being grasped in order to improve the tactile feel. For example, material inserts or moulded rubber or synthetic rubber inserts may be used. Preferably, where one side of the portion being grasped has a fabric surface, and the other side has a plastic moulding, then an insert will be placed strategically so that it is likely to be in the area which will be grasped by the user.

In order to fully understand the details of the invention described in this specification, a preferred embodiment will now be described. It should be realised that the invention is not to be confined or restricted to the details of this embodiment.

o• S 15 The embodiments are illustrated in the accompanying drawings in which: Fig 1 shows an exploded view of a back rest, back rest tube and back rest height adjustment assembly; S* Figs 2a and 2b show cross-sectional views of a back rest; Fig 3 shows a cross-sectional view of a seat leg, back rest tube pivot connection and 20 seat leg housing; and Fig 4 shows a plan view of Fig 3.

Fig 1 shows the back rest height adjustment assembly 10. The assembly comprises a back rest 11 an attached back rest sleeve 12 and a back rest tube 13 that locates within the back rest sleeve 12. The back rest tube 13 has a plurality of apertures 15 which act in conjunction with a rocker latch 16. The operation of the rocker latch is more clearly seen in Figures 2a and 2b. The rocker latch 16 has a projection 17 that engages within the apertures The rocker latch 16 is pivotally secured to the back rest sleeve 12 via pivots 19 and a spring (not drawn) is located under the end of the rocker latch 16 which is opposite to that of the projection 17. This always ensures that the projection 17 is biased towards the apertures 15 which holds the rocker latch 16 in place and thereby hold the back rest 11 with respect to the back rest tube 13.

The rocker latch 16 can be used to adjust the height of the back rest 11. The rocker latch is depressed against the action of the spring so as to disengage the projection 17 from the aperture 15. The rocker latch 16 is held in this position and the back rest moved to the desired position. Release of the rocker latch 16 will result in reengagement of the projection 17 with the aperture 15 thereby holding the back rest 11 in the required position.

The use of the rocker latch 16 is only suitable when a person is standing and can readily access the rocker latch 16. When a person is seated in the chair, this particular height adjustment means is difficult and uncomfortable to access.

Accordingly, an additional actuator 20 is provided. The actuator 20 comprises a 15 collar 21 that encircles the back rest tube 13 and a finger 22 that has a ramped surface 23 thereon. The actuator 20 is held in the back rest sleeve 12 by both a stud 25 which engages an aperture 26 within the back rest sleeve 12. In addition, the finger 22 has a shoulder 27 that locates on ledge 28. A spring 29 is formed within the actuator that is placed into tension when the stud 25 is placed within the aperture 26 and the 20 shoulder 27 is on the ledge 28. This, and the fact that a portion of the actuator 20 is between the inner surface of the back rest sleeve 12 and the back rest tube 13, effectively holds the actuator 20 in position when it is not being manually operated.

When the collar 21 of the actuator 20 is pushed upwardly, the ramp surface 23 abuts against the projection 17 of the rocker latch 16. Progressive upward movement pushes the rocker latch 16 so that the projection 17 disengages from the apertures This in turn allows the back rest 11 to move with respect to the back rest tube. This operation of the actuator 20 results in further extension of the spring 29. Obviously, upon release of the actuator 20, the spring returns the actuator to its start position thereby allowing the projection 17 of the rocker latch 16 to re-engage the apertures and hold the back rest 11 in position.

The insert for improving the tactile feel when grasping the back rest is illustrated in Figures 1, 2a and 2b. This comprises insert 31 which is moulded from a silicone rubber compound that is located within the moulded back rest outer 32. The insert 31 has a peripheral flange 33 that locates within recess 34 that is formed within the back rest outer 32. The peripheral flange 33 may have a ridge which locates behind respective shoulders in the recess 34.

The size and placement of the insert 31 will depend on the position in which it is to be located on the chair. In respect of the back rest 11, the insert 31 is large enough to ensure that there is a reasonable chance of a person's thumb or fingers grasping the insert 31 when the chair is to be moved. The soft feel of the silicone rubber insert 31 significantly improves the feel for the user.

Fig 1 illustrates a retainer 35 that is inserted into the end of the back rest tube 13 to 15 prevent any excessive movement between the back rest sleeve 12 and the back rest tube 13 that would otherwise result from clearance between the two components.

Clearly, the tolerances between the two components are such that it is impossible to ensure a smooth sliding fit without sideways movement.

20 Accordingly, the retainer 35 is designed to locate into the end of the back rest tube 13 with fittings that will hold it in place. There are a first series of projections 36 and 37.

These are not readily visible in Fig 1, but comprise small generally rectangular or oval shaped projections. A further projection 38, which is clearly shown in Fig 1 extends in the opposite direction to the projections 35 and 36.

The retainer 35 also has a pair of arms 39 that extend away from the retainer 35 in a plane which is normal to the direction in which the projections 36 to 38 extend.

The retainer 35 is moulded from a polymeric material, and the shape is such that the arms 39 and the projections 36 to 38 are resiliently movable. When the retainer 35 is inserted into the end of the back rest tube 13, the projection 36 protrudes out of an aperture in the back rest tube 13 (not drawn) and the projection 38 abuts against the top edge of the back rest tube 13. The projection 37 holds the retainer 35 in place.

That is the projections 36 and 37 would need to be depressed below the apertures to enable its removal. When the back rest tube 13 with its retainer 35 are inserted within the back rest sleeve 12, the projections 36 and 38 bear against the adjacent inside surfaces thereby preventing rocking in this particular direction. The arms 39 also bear against the inside surface of the back rest sleeve 12 thereby restraining rocking movement in that direction.

In order to prevent the back rest tube 13 from pulling freely out of the end of the back rest sleeve 12 a retainer plate (not drawn) is used. This retainer plate sits between the back rest tube 13 and the back rest sleeve 12 and has a projection that locates into the back rest sleeve 12. This effectively holds the plate captive in this °location. Accordingly, when the back rest sleeve 12 is pulled up to its maximum extension height, the projection 36 abuts against the plate and prevents any further 15 extension. This also of course prevents removal of the back rest sleeve 12 from the back rest tube 13.

In order to assemble this arrangement, the plate is put into position inside the back S. rest sleeve 12, and the back rest tube 13 is pushed in place. The projection 36 is 20 shaped so that it will be depressed into the back rest tube 13 and thereby will pass the retainer plate. It may have a ramp surface to facilitate this insertion. Once it is past the retainer plate, it has a vertical base ledge which abuts against the retainer plate and prevents projection 36 from passing. In order to disassemble the arrangement, the retention plate may have an aperture therethrough which enables a tool to depress a portion of the retainer 35 so that the projection 36 is pushed within the tube 13 thereby enabling it to pass the retainer plate.

The use of the retainer 35 has been described in relation to the back rest 11. However, it will be readily realised that such a retainer 35 and retainer plate is equally suited to a similar arm rest sleeve and will work in exactly the same way. In addition, a height adjustor for the arm rest may work in exactly the same way.

Figs 3 and 4 illustrate the seat height adjustor. This comprises a seat leg 40 which contains a conventional gas strut height adjustor. A height adjustor lever 41 is secured to the base or under seat leg housing 42. The lever 41 is pivotally attached to the housing 42 at its end 43 and is retained to the housing 42 by a portion which passes through an aperture 44. A height adjustment lever 45 is pivotally secured with respect to the leg 40. One end 46 passes over the height adjustment lever 41 and the other end 47 is over the top of the gas strut actuator 48. Obviously, by lifting the height adjustment lever 41, it bears against the first end 46 of the lever 45 which in turn causes the other end of the lever 47 to operate the gas strut actuator 48. This enables the chair to raise or lower.

The under seat leg housing 42 is pivotally attached to the leg 40 via pivot 49. This pivot 49 is spaced some distance from the gas strut actuator 48. Accordingly, any tilting of the seat via pivot 49 will have the tendency to alter the position of the first end 46 of the lever 45 with respect to the height adjustment lever 41. In order to prevent undesired operation of the gas strut actuator 48, the first end 46 of the lever 45 is curved as shown in Fig 3. This radius of curvature, which is in contact with the respective portion of the height adjustment lever 41, matches the radius described by S* rotation of the seat about pivot 49. This therefore ensures that the first end 46 of the S 20 lever 45 remains in contact with the height adjustment lever 41 as the seat is tilted and also ensures that the lever 45 is not moved during this tilting operation.

Accordingly, this arrangement as shown in Fig 3 and Fig 4 enables the height adjustment lever 41 to be attached to the housing 42 which in turn means that the end of the height adjustment lever 41 which is grasped for manual operation of the height adjustment mechanism can be located in a forward and more accessible position. In this embodiment, the end of the height adjustment lever 41 is in a forward corner of the seat. This is a much more convenient position in which to actuate the height adjustment, which would not be achievable if the height adjustment lever had to remain directly over the gas strut actuator 48.

Fig 3 also illustrates the pivot connection between the back rest tube 13 and the under seat leg housing 42. As seen in Fig 3, there is a first pivot connection 50 which pivotally connects the back rest tube 13 with respect to the housing 42. A second pivot connection 51 connects a link 52 between the back rest tube 13 and the clutch plate assembly 53. As is conventionally the case, the release of the clutch plate 53 mechanism enables the link 52 to slide with respect to the clutch plate assembly 53 thereby enabling rotation of the back rest tube 13 with respect to pivot In this example, the pivot 51 is located directly above pivot 50. This in turn means that the link 52 and the associated bracket 54 do not extend downwardly from the back rest tube 13 which would otherwise be the case with conventional pivot assemblies. Therefore, the current arrangement illustrated in Fig 3 enables the pivots 50 and 51, bracket 54 and link 52 to be fully located within the housing 42. This results in a much more desirable appearance.

0oo* It will be realised that minor variations can be made to the embodiments described o above but that these variations will still be seen as being within the scope of the Sinventive concepts described.

**0.0 0:00*

Claims (8)

1. A latch mechanism for controlling height adjustment of the back rest of a chair comprising: a back rest sleeve that is secured to the back rest of a seat with an open end a back rest tube, for supporting the back rest above a seat, that slidably locates within the back rest sleeve through the open end, a latching mechanism that allows height adjustment of the back rest with respect to the back rest tube, and actuating means for the latching mechanism that is located below and adjacent the open end of the back rest sleeve. o 2. A latch mechanism according to claim 1 wherein the actuating means comprises a collar that slides with respect to the back rest tube. o•

3. A latch mechanism according to claim 2 wherein the latching mechanism is operated by pushing the collar up towards the back rest sleeve. A latch mechanism according to claim 2 wherein the latching mechanism is *:oo 20 operated by pulling the collar down away from the back rest sleeve. A latch mechanism according to any one of the preceding claims wherein the latching mechanism comprises a spring loaded projection held in the back rest sleeve where the projection locates in one of a series of apertures in the back rest tube.

6. A latch mechanism according to claim 5 wherein the actuating means has a finger that is moved by the actuating means that in turn moves the latching mechanism projection into and out of the apertures in the back rest tube.

7. A latch mechanism according to claim 6 wherein the actuating means is spring loaded so that upon moving the latching mechanism projection out of an aperture, when it is released, the finger retracts and releases the latching mechanism projection.

8. A latch mechanism according to any one of claims 5 to 7 wherein the latching mechanism further comprises a pivoted plate, one end having a projection thereon, the other end comprising an actuating lever that may be depressed to move the projection out of an aperture.

9. A latch mechanism according to claim 8 wherein the finger has a ramped surface that is used to raise the end of the pivoted plate with the projection.

10. A latch mechanism according to any one of the preceding claims wherein the invention is used on an arm rest to raise and lower an arm rest with respect to an arm rest tube.

11. A latch mechanism as hereinbefore described with reference to and as illustrated in the accompanying drawings. Dated this 14th day of October, 1997. *e e s WORKSPACE COMMERCIAL FURNITURE PTY LTD •see: °By its Patent Attorneys MADDERNS 6v-l-4,