Chairs and seats – Back movement resiliently opposed in operating position – Back and seat adjust simultaneously
Reexamination Certificate
2001-10-16
2004-03-16
Cuomo, Peter M. (Department: 3636)
Chairs and seats
Back movement resiliently opposed in operating position
Back and seat adjust simultaneously
C297S300400, C297S342000, C297S322000, C297S316000
Reexamination Certificate
active
06705677
ABSTRACT:
TECHNICAL FIELD
This invention relates to a chair having a seat and a seatback in which the seat and the seatback can be tilted between a working position and a relaxing position, and a rotary damper which is suited to be used for the chair and others.
BACKGROUND ART
A conventional chair with a seatback is disclosed in Japanese Patent Application Laid-Open No. H06-253940. This chair with a seatback comprises a main frame disposed at an upper end of a support leg, a seatback frame whose forward end is turnably disposed at the main frame, thereby enabling the seatback, which is disposed at an upper part of a rear end side, can be tilted between a working position and a relaxing position, and a seat frame at which the seat is disposed. A rear end part of the seat frame is turnably connected to the seatback frame. On the other hand, a forward end part of the seat frame is connected to the main frame through a positive motion cam mechanism. The positive motion cam mechanism comprises a cam hole formed in the main frame, and a shaft portion disposed at the seat frame and movably engaged with said cam hole. When the rear end part of the seat frame is moved upward and downward in accordance with the turning motion of the seatback frame, the positive motion mechanism causes the entire seat frame to move in forward and backward, upward and downward directions and tiled in an upward and downward direction in accordance with the turning motion of the seat frame in upward and downward directions.
The chair with a seatback further comprises bias means for biasing the seat frame and the seatback frame from the relaxing position side towards the working position side. The bias means biases the seat and the seatback in a working position when a person is not sitting on the seat, but it allows the seat and the seatback to be tilted in the relaxing position side when he leans against the seatback, depending on the load acting on the seatback.
The above-mentioned conventional chair with a seatback has the following various problems. First, since the cam hole of the positive motion cam mechanism is required not only to move the seat frame in a forward and backward direction but also to displace and tilt the seat frame in an upward and downward direction, the length of the cam hole must be long in an upward and downward direction. Accordingly, the main frame is also required to be increased in length in its upward and downward direction in accordance with the length of the cam hole in an upward and downward direction. For this reason, the chair with a seatback is difficult to be made small in size.
Second, if a comparatively large load acts on the seatback when a biasing force of the bias means for biasing the seat and the seatback from a relaxing position side to a working position side is small, the seat and the seatback are tilted from the working position towards the relaxing position at a high speed. As a result, the person sitting on the chair gets such an anxiety that the chair may be fallen down. If the biasing force of the bias means is increased, there occurs such an inconvenience that when, for example, the user of the chair changes his attitude in the relaxing position and as a result, the load acting on the seatback is reduced, the seat and the seatback is turned back to the working position side against the user's will.
Third, the seatback is supported on the main frame through a support arm but the conventional support arm is formed substantially as a rigid body. Accordingly, the seatback cannot be turned in a horizontal direction. For this reason, when the user turns backwards in a state in which he sits on the chair with a seatback, he cannot twist his body with his back kept contacted with the seatback and therefore, he must move his back forward from the seatback once.
DISCLOSURE OF INVENTION
The first form of the present invention is to solve the first problem and provides, therefore, a chair with a seatback comprising a main frame, a seat frame arranged at an upper part of the main frame, a seatback frame whose forward end part is connected to a forward end part of the main frame such that the forward end part can turn about a horizontal axis, thereby enabling a rear end part of the seatback frame to be tilted between a working position and a relaxing position, a displacement mechanism disposed between the rear end part of the seat frame and the seatback frame and adapted to displace the rear end part of the seat frame in an obliquely forward/backward direction in accordance with the turning motion of the seatback frame, and a positive motion cam mechanism for displacing the seat frame upward and downward, forward and backward and for tilting the seat frame upward and downward in corporation with the displacement mechanism, wherein the positive motion cam mechanism is disposed between the forward end part of the seat frame and the forward end part of the seatback frame.
In this case, it is preferred that the positive motion cam mechanism includes a cam hole and a shaft movably inserted in the cam hole in a longitudinal direction of the cam hole, one of the cam hole and the shaft is disposed at the seat frame and the other is disposed at the seatback frame. The cam hole is preferably disposed at the seatback frame.
It is preferred that the displacement mechanism includes a link connected at a lower end part thereof to the main frame such that the link can turn about a horizontal axis and at an upper end part thereof to a rear end part of the seat frame such that the link can turn about a horizontal axis, a second positive motion cam mechanism disposed between an upper end part of the link and the seatback frame and adapted to cause the link to turn in accordance with the turning motion of the seatback frame, and the second positive motion cam mechanism includes a second shaft movably inserted in the second cam holes disposed at one of the upper end part of the seatback frame and the second cam hole disposed at the other and movably inserted in the second cam hole.
It is preferred that the main frame is provided with an engagement member removably engaged with the link and adapted to positionally fixing the seatback frame to the working position by prohibiting the turning of the link at the time of engagement.
It is preferred that a lower end part of a shielding member is disposed at a forward end part of the main frame such that the shielding member can turn about a horizontal axis, the shielding member is adapted to shield a gap formed between a forward end part of the main frame and the seat frame or a seat cushion disposed at the seat frame, and an upper part of the shielding plate is connected to a forward end part of the seat frame such that when the gap varies in size in accordance with the displacement of the seat frame, the shielding plate is turned in accordance with the size of the gap.
A second form of the present invention is to solve the second problem and provides, therefore, a chair with a seatback comprising a seat capable of tilting between a working position and a relaxing position, a seatback capable of tilting in accordance with a tilting motion of the seat, and bias means for biasing the seat from the relaxing position side to the working position side, wherein the chair with a seatback further comprises a rotary damper (
180
) for restricting a high speed tilting of the seat at least in one direction between the working position and the relaxing position.
In this case, it is accepted that the rotary damper restricts a high speed tilting of the seat from the working position side to the relaxing position side but allows a high speed tilting of the seat from the relaxing position side to the working position side. It is also accepted that the rotary damper restricts a high speed tilting of the seat from the relaxing position side to the working position side but allows a high speed tilting of the seat from the working position side to the relaxing position side. However, it is preferred that the rotary damper restricts a high speed tilting of the seat i
Masuda Hiroyuki
Oshima Kazuyoshi
Brown & Michaels PC
Cuomo Peter M.
Edell Joseph
Eugene Stephens & Associates
Sugatsun Kogyo Co., LTD
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