Self-adjusting general-purpose chair with a cantilever type seat fixed on the front side of the seat

Abstract

In the present invention, a general purpose chair, using a construction with a cantilever type seat (20) fixed on the front side (21) of the seat, and with a free end on the back side of the chair, solves the problem of self adjusting of the height of the low back support (3) for users of various body heights and in various sitting positions, in the manner that does not need an active action of the user. With changing the flash of the cantilever for various users and with changing the flash when moving back and forward on the seat, the condition of comfortable and anatomically correct support is fulfilled for majority of users and positions.

Description

[0001] The present invention is related to the field of furniture design and it concerns the furniture with improved construction as regards aspect of anthropometrics, enabling the anatomical adjustment in the sitting position. More specifically, the invention is related to a general purpose chair with a cantilever type seat fixed on the front side of the seat, which enables the anatomical adjustment of low back support for users of various body heights and various weights, as well as in various sitting positions.TECHNICAL PROBLEM[0002] This invention solves the problem of automatically adjusting chairs with anatomical chair back shape, having a concentrated pressure on the low back of a sitting person. Since a comfortable and anatomically correct sitting requires that a concentrated pressure of the persons back on the chair back should be in the point of the low back (lumbal zone), it is necessary to find a way to adjust this position for users of various body heights, i.e. various...

AI Technical Summary

Benefits of technology

[0011] Here described invention represents a method which solves the problem of self adjustment of lumbal zone support height for users of various body heights and in various sitting positions, without an active user's action, by using a chair seat construction of cantilever type fixed on the front side of the chair, with free end on the back side of the chair. This function of self-adjustment is based upon assumption that a great number of users have height and weight, that can be approximated by a linear dependence (the taller the user-the larger the weight.). Since the cantilever deformation depends upon the applied force, a taller and havier user will cause larger deformation, which with most users enables direct leaning of the lumbal zone on the lumbal support. Solution of the problem of chair self adjustment for user's moving forward-backwards on the seat, is based on the fact that cantilever deformation decreases by shortening of effective cantilever length (with the same vertical pressure on the seat). When users move forward, the effective length of cantilever (and it's deformation) decreases, and the height of lumbal support in relation to the seat level also decreases, so that the position of the lumbal zone center comes very close to lumbal support center, when moving back or forward to any sitting position. In this way the chair offers a comfortable, i.e. anatomically correct support for most users and most sitting positions.

Problems solved by technology

The second problem is that the sitting itself, being a dynamical activity, involves temporary a spontaneous changing of sitting position by moving back and forward on the seat.

1. Most chairs are designed with fixed seat und fixed chair back and in no case consider the necessity of supporting the lumbal zone, for example the chairs with flat chair back.

2. There are also chairs with fixed seat and fixed chair back with anatomical chair back profile in the lumbal zone. However, this does not solve the problem of adaptation for users of various body heights. It also does not solve the problem of adaptation when moving on the seat, as shown in the FIG. 2. This is the reason why this type of chairs is convenient for only a small number of users and is not suitable for various sitting positions.

3. There are also some chair types with seats and chair backs adjusted by means of some elements such as screws, springs and similar, which are used for fixing and unfixifing seats and chair backs. For such adjustments, it is necessary to have an active user's action. Such adjustment is only partly comfortable, in case when a user takes a seat and adjusts the chair for himself, but becomes rather uncomfortable for compensation of spontaneous moving of the body during the sitting.

4. There are also chairs with various solutions of self-adjustment while changing sitting position. These are mainly solutions with flexible chair back, where the moving axis of the chair back is located in seat surface level or in the level of the lumbal zone (as shown in the FIG. 3). Such solutions are not meant to solve any of the mentioned problems or they solve them only partly, such as the chair shown in the FIG. 3 which solves the problem by reducing the distance the support point and the lumbal zone (points 6 and 7) in comparison to the simple chair shown in the FIG. 2 (points 4 and 5).

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