Chairs and seats – Movable back – Tiltable
Reexamination Certificate
2001-09-21
2002-10-22
Barfield, Anthony D. (Department: 3636)
Chairs and seats
Movable back
Tiltable
C297S300800, C297S463100
Reexamination Certificate
active
06467845
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a chair, more particularly to a chair which is provided with a locking unit for locking a backrest or a seat relative to a stationary frame after adjustment of an angle between the backrest or the seat and the stationary frame.
2. Description of the Related Art
Referring to
FIGS. 1
to
3
, a conventional chair
1
is shown to include a chair seat
130
, a backrest
140
, a backrest support arm
16
, a backrest bracket
161
, a seat frame
15
, a linking member
121
, and a locking unit
17
.
As illustrated, the seat frame
15
is disposed under the seat
130
, and has opposite left and right sidewalls
151
,
152
. The backrest bracket
161
is disposed rearwardly of the seat frame
15
, and has an upper portion
1611
disposed between and pivoted to the left and right side walls
151
,
152
of the seat frame
15
so as to be turnable relative to the seat frame
15
.
The backrest support arm
16
has a top connected to the backrest
140
, and a bottom connected to the backrest bracket
161
so as to be turnable therewith.
The linking member
121
has a front part disposed between the left and right side walls
151
,
152
of the seat frame
15
and formed with an arcuate slot
123
defined by a slot defining wall, and a rear part connected to a lower portion
1612
of the backrest bracket
161
so as to be movable therealong.
The locking unit
17
includes a stationary clamping seat
18
, a movable bolt
122
, a movable clamping member
125
, a cam member
171
, and an operating lever
172
. The stationary clamping seat
18
is mounted on the right side wall
152
of the seat frame
15
, has a clamping end
180
disposed between the right side wall
152
and the front part of the linking member
121
. The movable bolt
122
has opposite left and right ends, and extend through the left and right side walls
151
,
152
of the seat frame
15
, the clamping end
180
of the stationary clamping seat
18
, and the arcuate slot
123
in the linking member
121
in such a manner that the slot-defining wall moves relative to the movable bolt
122
so as to prevent interference between the linking member
121
and the movable bolt
122
when the linking member
121
turns together with the backrest bracket
161
relative to the seat frame
15
. The movable clamping member
125
, which is in the form of a tubular sleeve, is sleeved on the movable bolt
122
so as to be movable therewith. The cam member
171
is pivoted to the seat frame
15
via a pivot
175
, and has two cam faces
173
,
174
for abutting against a head end of the movable bolt
122
. The operating lever
172
is fixed to and extends outwardly from the cam member
171
. The operating lever
172
is turnable downwardly about the pivot
175
so as to move the movable bolt
122
to a locking position, in which the bolt
122
is urged by a high strength coil spring
124
to move toward the right side wall
152
and to abut against the cam face
174
, and in which a clamping end of the movable clamping member
125
cooperates with the clamping end
180
of the stationary clamping seat
18
to provide a clamping force to clamp the linking member
121
so as to immobilize the linking member
121
relative to the seat frame
15
and so as to prevent turning of the backrest bracket
161
with respect to the left and right side walls
151
,
152
of the seat frame
15
. The operating lever
172
is turnable upwardly about the pivot
175
so as to move the movable bolt
122
to an unlocking position, in which the cam face
173
abuts against the head end of the movable bolt
122
, and in which the movable bolt
122
moves against the urging force of the spring
124
toward the left side wall
151
of the seat frame
15
so as to release the linking member
121
from being clamped between the movable clamping member
125
and the stationary clamping seat
18
.
Some disadvantages encountered during use of the aforesaid conventional chair
1
are as follows:
In order to move the movable bolt
122
between the locking and unlocking positions, a high strength coil spring
124
is employed in the conventional chair. Such type of spring
124
is costly to manufacture. In addition, the spring
124
will suffer from spring fatigue after long term use and will, in turn, affect the locking effect of the locking unit
17
.
Furthermore, the cam member
171
has to be manufactured from a high strength material, such as metal, so as to withstand the high compression force of the spring
124
. As such, the manufacturing cost is relatively high.
SUMMARY OF THE INVENTION
The object of this invention is to provide a chair that is provided with a locking unit which can be manufactured from low cost materials so as to eliminate the aforesaid disadvantages resulted.
Accordingly, a chair of the present invention includes a seat frame, a backrest bracket, a backrest support arm, a linking member, and a locking unit. The seat frame has opposite left and right side walls. The backrest bracket is disposed rearwardly of the seat frame, and has an upper portion disposed between and pivoted to the left and right side walls so as to be turnable relative to the seat frame. The backrest support arm has a bottom connected to the backrest bracket so as to be turnable together therewith. The linking member has a front part which is disposed between the left and right side walls of the seat frame and which is formed with an arcuate slot, and a rear part which is connected to a lower portion of the backrest bracket so as to be movable therewith. The locking unit includes a stationary clamping seat, a movable bolt, a movable clamping member, a generally C-shaped connector, and an operating lever. The stationary clamping seat is mounted on the right side wall of the seat frame, and has a clamping end that is disposed between the right side wall and the front part of the linking member. The movable bolt has opposite left and right ends, and extends through the left and right side walls of the seat frame, the clamping end of the stationary clamping seat, and the arcuate slot which permits the linking member to move past the movable bolt without interfering the movable bolt when the linking member turns with the backrest bracket relative to the seat frame. The movable clamping member is mounted on the movable bolt, and has a clamping end that is disposed between the left side wall of the seat frame and the front part of the linking member so as to be movable along with the movable bolt. The C-shaped connector has a left section connected to the right end of the movable bolt at a contact point, and a right section. The operating lever has a left end pivoted to the right section of the C-shaped connector about a first pivot, and a left extension which extends from the left end of the operating lever toward the left section of the C-shaped connector and which is pivoted to the right side wall of the seat frame about a second pivot. The second pivot extends parallel to the first pivot, and is located between the left and right sections of the C-shaped connector. The operating lever is turnable upwardly and downwardly so as to move the movable bolt via the C-shaped connector between a locking position, in which the clamping end of the movable clamping member cooperates with the clamping end of the stationary clamping seat to provide a clamping force to clamp the linking member so as to immobilize the linking member relative to the seat frame and so as to prevent turning of the backrest bracket with respect to the left and right side walls of the seat frame, and an unlocking position, in which the movable bolt moves toward the left side wall of the seat frame so as to release the linking member from being clamped between the movable clamping member and the stationary clamping seat. When the movable bolt is at the locking position, the linking member counteracts the clamping force, which results in a pulling force that pulls the left end of the operating lever in a direction toward the left side wall al
Barfield Anthony D.
Christie Parker & Hale LLP
Garrett Erika
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