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1. Field of the Invention
The present invention relates to an office chair, and more particularly to an apparatus for adjusting the angle of a seat back of an office chair.
2. Description of the Related Art
In addition to meeting the ergonomic requirement, the design of an office chair must fulfill the requirement of providing the user with a comfortable sitting feeling. It is more preferable when the angle of the seat back can be adjusted. As shown in FIG. 1, a conventional office chair 10 substantially includes a padded seat 11 that is supported by a supporting base 12 at the bottom thereof. A seat back 13 is positioned at the rear end of the padded seat 11. The upper part of the body of the user can lean backward against the seat back to take a rest when he is tired. However, the seat back 13 and the padded seat 1 are linked by an L-shaped bar 14. Therefore, the position of the seat back 13 is changeless. Therefore, a comfortable slanting angle is not available when the user leans backward.
As shown in FIG. 2, another conventional office chair 20 is substantially identical to the structure in FIG. 1 except the external contour. Referring to FIGS. 3A and 3B, the office chair 30 is an angle-adjustable office chair. A supporting seat 34 is interposed between a padded seat 31 and a supporting base 32. In other words, the bottom of the supporting base 34 is pivotally connected to the top end 323 of the supporting base 32. A spring 322 is positioned at the front end of the supporting base 34 for providing a restoring force when the supporting base 34 is inclined backward. This structure permits a backward slanting action of the seat back 33. However, both the seat back 33 and the padded seat 31 perpendicular to each other to form an L-shape are moved backward together. This is not suitable for the one who only likes that his back leans backwards and doesn't like that the seat is raised. Moreover, the supporting base 34 has to be subject to the whole gravitation produced by the swiveling action of the whole seat body, thereby leading to the fact that the whole structure becomes more bulky. As a result, the flexibility of the office chair is not achieved. In addition, the structure, that the padded seat 31 can lean backward, easily loses the center of gravity. Furthermore, the user has to be more careful in use; otherwise, the whole chair might be tipped over backward.
It is a primary object of the invention to provide an apparatus for adjusting the angle of a seat back of an office chair by which the seat portion remains unmoved while the seat back leans backward with the back of the user and permits an automatic adjustment of the inclination to an optimal level, thereby providing the user with a comfortable sitting feeling.
It is another object of the invention to provide an apparatus for adjusting the angle of a seat back of an office chair that has a simple structure and permits a flexible and free operation. Meanwhile, the center of gravity won't be changed in adjusting the seat back. In this way, the safety in use may be increased.
In order to achieve the above-mentioned objects, an apparatus for adjusting the angle of a seat back of an office chair includes:
a) a supporting base;
b) a seat body mounted on the supporting base;
c) a seat back having a pair of elongated ears symmetrically parallel to each other and disposed at the bottom end of both sides thereof, the elongated ears each being pivotally connected to the rear side of the seat body; and
d) an elastic support element slantly disposed at a lower location between the bottom end of the seat back and the rear end of the seat body.
Based upon the above-mentioned configuration, a strong elastic supporting force is provided for the seat back. As a result, the inclination of the seat back can be automatically adjusted when the body of the user leans backward.
The accomplishment of this and other objects of the invention will become apparent from the following descriptions and its accompanying figures of which:
FIG. 1 is a perspective view of a conventional office chair;
FIG. 2 is a perspective view of another conventional office chair;
FIG. 3A is a side view of a conventional angle-adjusting office chair;
FIG. 3B is a perspective partial view of the angle-adjusting office chair in accordance with FIG. 3A;
FIG. 4 is a perspective view of a preferred embodiment of the invention;
FIG. 5 is a perspective assembly view of the preferred embodiment of the invention;
FIG. 6 is a side view of the preferred embodiment of the invention;
FIG. 7 is an enlarged view of the main structure of the invention; and
FIG. 8 is a schematic drawing of the operation of the invention.
First of all, referring to FIGS. 4 through 6, a preferred embodiment of the invention includes a supporting base 40, a seat body 50, a seat back 60, and an elastic support element 70.
The supporting base 40 has a shaft 41 in the middle thereof. The supporting base 40 in accordance with the embodiment includes casters 42 at the bottom thereof.
The seat body 50 includes a shaft socket 51 at the center of the bottom side thereof. The shaft socket 51 is mounted on the shaft 41. According to this embodiment, the seat body 50 includes a padded portion 54 and two armrests 55 at both sides thereof. These are basic components of a normal office chair so that no further descriptions thereto are given hereinafter.
The seat back 60 includes a pair of elongated ears 61 that are symmetrically parallel to each other and disposed at the left and right sides thereof. The elongated ears 61 each are pivotally connected by a first pivot element 611 to a first mounting portion 52 at the rear side of the seat body 50. Moreover, a projecting ear 62 is positioned at the center between the left and right elongated ears 61 of the seat back 60.
The elastic support element 70 includes a first pivoting portion 71 at the top end thereof. The first pivoting portion 71 is pivotally connected by a second pivot element 621 to the projecting ear 62 of the seat back 60. Meanwhile, a second pivoting portion 75 at the bottom end of the elastic support element 70 is pivotally connected by a third pivot element 751 to a second mounting portion 53 of the shaft socket 51 positioned at the bottom end of the seat body 50 (see FIG. 7). In this way, the elastic support element 70 is slantly disposed at a lower location between the bottom end of the seat back 60 and the rear end of the seat body 50.
Referring to FIG. 7, which is an enlarged sectional view of the main structure in FIG. 6, the elastic support element 70 includes a guide bar 72 pivotally connected at the bottom end of the first pivoting portion 71. The bottom portion of the guide bar 72 axially passes through a socket 76 above the second pivoting portion 75 and in an inclined position. The socket 76 is axially fixed within a hollow tube 74 with an opening directed upwards. A spring 73 is mounted on the guide bar 72 and the socket 76.
The first, second, and third pivot elements 611, 621, 751 are selected from a group consisting of a bolt and a pin. The second pivoting portion 75 and the socket 76 of the elastic support element 70 are integrally formed to be an L-shaped body.
Based upon the above-mentioned configuration, the sound-deadening effect of the invention can be achieved by the following ways. The socket 76 is used to position the guide bar 72 in place. As shown in FIG. 7, three pivoting points A, B, C are formed between the seat back 60 and the seat body 50 to be a triangular shape . . . An in-place swiveling action takes place on the pivoting points A, C while an arched swiveling action occurs on the point B. In other words, as shown in FIG. 8, the seat back 60 swivels about pivoting points A, B, C for the adjustment of the angle. As a result, the seat back 60 is subject to an automatic angle-adjustment by means of the elastic support element 70 when the user rests on the seat back 60. Besides, a comfortable and smooth change of the elevation angle is achieved without moving the seat body 50. Therefore, the center of gravitation won't be changed such that the safety in use can be guaranteed.
Many changes and modifications in the above-described embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, to promote the progress in science and the useful arts, the invention is disclosed and is intended to be limited only by the scope of the appended claims.