Chairs and seats – Back movement resiliently opposed in operating position – Back adjusts independent of seat
Reexamination Certificate
2002-02-01
2003-12-09
Brown, Peter R. (Department: 3636)
Chairs and seats
Back movement resiliently opposed in operating position
Back adjusts independent of seat
C297S301700, C297S376000
Reexamination Certificate
active
06659554
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an adjustment device of a chair backrest, and more particularly, an adjustment device that is easy to use and can firmly fix the chair backrest after the adjustment.
Referring to FIGS.
6
~
9
, a conventional adjustment device of a chair backrest includes a fixed member
51
, a movable member
52
, a fixing member
53
and an elastic member
54
. The fixed member
51
is secured to the bottom of the seat of a chair by means of screws passing through holes
511
thereof, and has two opposing lateral parts, which each has a through hole
512
and a curved slot
513
.
The movable member
52
also has two opposing lateral parts
521
, which each has a through hole
522
, a connecting hole
524
and a through hole
525
. The movable member
52
further has an insertion hole
523
, through which a supporting rod of a backrest
58
is passed.
The movable member
52
is received in, and pivotably connected to, the fixed member
51
with a rod
56
passing through the through holes
522
as well as the through holes
512
.
The elastic member
54
is disposed between the lateral parts
521
of the movable member
52
, and has an upper end portion, a middle connecting portion, and lower end hooked portions. The rod
56
is passed through the middle portion of the elastic member
54
such that the upper end portion of same abuts the lower side of the fixed member
51
. A rod
57
is passed into the connecting holes
524
of the movable member
52
and engage the lower end hooked portion of the elastic member
54
such that the rear end of the movable member
52
is biased up by the elastic member
54
.
The fixing member
53
is connected to a first one of the through holes
525
by means of a bolt
531
passing through the first through hole
525
, and the corresponding curved slot
513
.
Thus, the fixing member
53
can be burned between a loose position for allowing the movable member
52
to be adjusted in respect of the orientation in relation to the fixed member
51
, and a tight position for fixing the movable member
52
to the fixed member
51
.
U.S. Pat. Nos. 1,932,618 GABB, 1,263,162 TRAVERS, 2,272,980 MCLELLAN ETAT, 3,709,525 POTHERMEL, 6,220,664 LEE, ITALIAN Patent No. 672,811 NIENBURGER, BRITISH Patent No. 857,525 THOMPSON, and SWEDISH Patent No. 127,140 GABB also have adjustment devices of the same feature, i.e. the curved slots for allowing the movable member to move relative to the fixed member.
However, the above mentioned adjustment structure is found to have a drawback that the fixing member
53
can't firmly fix the movable member
52
after the adjustment because the lateral parts of the fixed member
51
are flat and smooth, and is likely to move relative to the fixing member
53
, especially when a person is sitting onto the chair. Consequently, the orientation of the chair backrest in relation to the seat after adjustment is unwantedly changed.
SUMMARY OF THE INVENTION
Therefore, it is a main object of the present invention to provide an adjustment device for a chair backrest such that the backrest can be firmly fixed in position after adjustment, without possibility of unwanted change of orientation in relation to the seat.
The adjustment device of the present invention includes a fixed member, a movable member, an elastic member, and a fixing member, which takes the form of a spanner.
The fixed member is fixed to the bottom of the seat. The movable member is pivoted to the fixed member. The backrest is connected to the rear end of the movable member. The fixing spanner is connected to an outer end of a bolt passing through both a lateral curved slot of the fixed member and a hole of the movable member from a connecting end portion thereof so as to be turnable between an unlocking position for allowing adjustment of the backrest and a locking position for fixing the movable member in position after the adjustment. The elastic member biases the rear end of the movable member upwards.
The fixed member further has a curved bump enclosing the curved slot; the bump has a lateral tapering side with an upper portion bigger than a lower portion thereof.
REFERENCES:
patent: 2585447 (1952-02-01), Eichorst
patent: 3601444 (1971-08-01), Doerner
patent: 4720142 (1988-01-01), Holdredge et al.
patent: 4953259 (1990-09-01), Frye et al.
patent: 6220664 (2001-04-01), Lee
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