CHAIR WITH ADJUSTABLE BACK

Abstract: The invention relates to a back support adjustment device (1) for chairs, including a pillar (2) upwardly directed from the seat or its substructure for carrying a back support (3), this pillar comprising at least two hollow sections (4, 5). The latter are positionally fixable to each other at a desired height for the back support by a tongue (6) formed in, and integral with, a wall of the outer hollow section (5) at a face (7) thereof, the tongue thus being enabled, with the aid of a force applied to it, to lock the inner section (4) to the outer (5) using friction and without making press marks on the face of the hollow section, against which compressive force is applied.

Description: r.ha -i r wi f-h af\ j n gt-ahl f- back The present invention relates to a back support height adjustment device for chairs, and includes a pillar upwardly directed from the seat or its substructure for carrying a back support, which is adjustable in rela¬ tion to the seat, the pillar comprising at least two hollow sections, which are mutually, telescopically displaceable. Implementations usually available at present for adjus¬ ting the height of pillars carrying a back support can be either complicated or simple structures. The compli¬ cated kind is expensive to produce and the simple kind, which is cheap to produce, has, inter alia, the draw¬ back that ugly clamping marks are caused on the means forming the pillar, these means being mutually dis¬ placeable for enabling different height settings for the back support. Another drawback with the simple structures is that when adjustment takes place, it happens quite often at greater heights that the part of the pillar means to which the support is attached is pulled out from the part with which it telescopes, causing it to fall on the floor together with the support. The object of the present invention is to provide a back support adjustment device of the kind mentioned above, which answers its purpose excellently, while being both simple and cheap in manufacture at the same time. The locking mechanism, used to positionally fix the telescoping hollow sections in given mutual rela¬ tionship, has an implementation making it impossible to form any ugly clamping marks on the sections. In addi- tion, the two sections forming the pillar means cannot slide apart into separate relationship. This situation is prevented by a locking pin, which keeps both sec- tions together until released by a simple thumb-grip in case the chair is to be dismantled, e.g. for transport and/or packing. The invention will now be described in more detail with the aid of a preferred embodiment example and with reference to the accompanying drawings, where Fig. 1 is a schematic, perspective view of a back support adjustment device in accordance with the pre¬ sent invention, Fig. 2 is a side elevation of a hollow section with associated means for attaching it to a chair seat or the substructure thereof and constitutes the lower part of the pillar means, Fig. 3 is a second side elevation of the hollow section in Fig. 2 and Fig. 4 is a plan of the hollow section in Fig. 2. As will most easily be seen from Fig. 1, a preferred embodiment example of the invention comprises a back support adjustment device 1 for a chair, including a pillar 2 upwardly directed from the seat or its sub¬ structure, for carrying a back support 3. In the illu¬ strated example the pillar 2 comprises at least two hollow sections 4, 5, which are mutually, telescopic- ally displaceable, and in the present example they have rectangular cross-sections. Since the hollow sections 4, 5 can move inside the section (5), a desired back support height can be achieved by pushing the former into, or withdrawing it from the latter, and since the pillar 2 is provided with a locking mechanism 23 actu- atable by a screw 9 via a thumb-wheel 24, the sections 4, 5 are readily, positionally fixable at a desired setting position. The actual positional fixation of the sections 4, 5 to each other is achieved with the aid of at least one tongue 6 formed in, and integral with, a wall of the outer hollow section 5 at a face 7 thereof. This tongue is intended to lock the two sections 4, 5 together by friction caused by applying a compressive force to it, which is achieved by operating the thumb-wheel 24 with its attached screw 9. By reason of the large engagement surface of the tongue 6 against the face 7• of the inner section 4 there will be no clamping marks on this face after actuating the mechanism 23 such as to lock the sections 4 and 5 to each other in different posi¬ tions in relation to each other. The screw 9, providing compressive force against the tongue 6, coacts via a thread 10 with a thread 11 in a yoke 8 surrounding the tongue 6 and fastened to the outer section 5. In order to provide uniform force distribution from the screw 9 to the inner section 4, the free end 12 of the screw is adapted to press against a centrally situated portion 13 of the tongue 6, the free end of which is flush with the free end 14 of the section 5, where the section 4 may be inserted. The tongue is laterally delimited by two slits 15, 16 in spaced relationship and departing from the free upper end 14 of sections 5 and in its longitudinal direction. The width of the tongue 6 substantially corresponds to the width of the face 7 1 of section 4, against which face it engages. In the example illustrated, slits 15, 16 delimiting the tongue 6 extend mutually parallel to terminate a dis¬ tance from the free end 14 of section 5 substantially corresponding to its width. In the region 18 where the slits terminate there is a hole 17 between them, pro- viding greater flexibility to the tongue 6 at its junction with the wall of section 5. The hole 17 also has the task of accommodating a lock- ing pin 19, which is spring-biassed away from section 4, such as to prevent, by coacting with the upper edge 20 of the hole, that sections 4 and 5 are unintention¬ ally pulled apart. Pushing the sections together is, however, always possible, since the downward edge portion 21 of the hole is curved away, or oterhwise rounded, at 22 so as to allow automatic depression of the pin into the inner section 4. When it is desired to separate the two sections 4 and 5, the pin 19 project¬ ing into the hole 17 can be depressed by the thumb, so that the pin glides under the upper edge 20 of the hole 17, which allows the sections 4 and 5 to be pulled apart.

Claims: Claims 1. Back support adjustment device for chairs, in¬ cluding a pillar (2) upwardly directed from the seat or its substructure for carrying a back support (3) , said pillar (2) comprising at least two hollow sections (4, 5) , which are mutually, telescopically displaceable, and are mutually, positionally fixable at a desired height with the aid of at least one tongue (6) formed in, and integral with a wall of the outer hollow sec¬ tion (5) at a face (7) thereof, the tongue also being laterally delimited by two slits (15, 16) in spaced relationship and departing from the free upper end (14) of said hollow section, the tongue thus being enabled, with the aid of a compressive force normal to it, to lock the other hollow section (4) against the first (5) with the aid of friction between said tongue and wall face (7') of hollow section (4), such as not to leave any clamping marks on the surface of this section (4) , against which the force is exerted, characterized in that in a region (18) at the termination of the slits (15, 16) the tongue (6) has a hole (17) between said slits for increasing flexibility of said tongue, where it is integrated into the face (7) of said outer hollow section (5) , the hole (17) also being utilized for accommodating a locking pin (19) , which is spring- biassed away from said section (4) and may be pressed inwards to allow hollow sections (4, 5) to be separated from each other. 2. Device as claimed in claim 1, characterized in that said compressive force is caused by a locking screw (9) , which may be urged against the tongue with the aid of a yoke (8) fastened to the outer section (5) and surrounding the tongue (6) . 3. Device as claimed in claim 2, characterized in that said screw (9) is provided with a thread (10) coacting with a corresponding thread (11) in said yoke (8) , the free end (12) of said screw (9) being disposed for pressing against a centrally situated portion (13) of said tongue (6) . 4. Device as claimed in claim 1, characterized in that the hollow sections (4, 5) have a rectangular cross-section and that the tongue (6) on the outer section (5) has a width substantially corresponding to the width of the inner section (4) . 5. Device as claimed in claim 1, characterized in that the slits (15, 16) delimiting the tongue (6) are mutually parallel and terminate at a distance from the free edge of the outer section (5) substantially corre¬ sponding to the width of this section.

Inventors: DU REES STEPHAN, DU REES, STEPHAN
Applicants: MERCADO MEDIC AB, REES STEPHAN DU, DU REES, STEPHAN
Application year: 1996
Main classification: A47C1
IPC codes: A47C7