Chair

Claim 2

A chair and comprising, a forward facing base frame fixedly mounted to an upper end of a pillar, a lower part of a supporting lever provided with a back rest movably and rotatably mounted on a lower rear part of said base frame by a shaft extending from one side of said chair to another side thereof, a seat including in succession a front seat portion and rear seat portion flexibly coupled together by a flexing part adjacent the center of said seat between the front and rear seat portions and being coupled to said supporting lever so as to cooperate therewith, and wherein said front seat portion is locked to a front part of said base frame so as to prevent inclining movement thereof but permit movement thereof only back and forth.

Claim 3

A chair according to claim 1, and further comprising, a seat supporting plate provided on a back surface of said seat, said plate having a flexible part adjacent a central portion thereof.

Claim 4

A chair according to claim 2, wherein said rear seat portion is constructed so as to be able to cooperate with said supporting lever and is centered on an axis which is coaxial with said supporting lever.

Claim 5

A chair according to claim 2, wherein a slide fitting is attached to a lower surface of said seat supporting plate on a front portion thereof so as to be slidable almost horizontally with respect to a flange which is provided on a front part of said supporting lever.

Claim 6

A chair according to claim 2, and further comprising a rear seat support attached to a lower surface of the seat supporting plate at a rear portion thereof, said rear seat support being pivotably mounted on said supporting lever.

Claim 7

A chair according to claim 5, wherein said rear seat portion is constructed so as to be able to cooperate with said supporting lever and is centered on an axis which is coaxial with said supporting lever.

Claim 8

A chair according to claim 5, wherein a slide fitting is attached to a lower surface of said seat supporting plate on a front portion thereof so as to be slidable almost horizontally with respect to a flange which is provided on a front part of said supporting lever.

Claim 9

A chair according to claim 1, wherein said rear seat portion is constructed so as to cooperate with said supporting lever and is centered on an axis which is coaxial with that of said supporting lever.

Claim 10

A chair according to claim 8, wherein a slide fitting is attached to a lower surface of said seat supporting plate on a front portion thereof so as to be slidable almost horizontally with respect to a flange which is provided on a front part of said supporting lever.

Claim 11

A chair according to claim 1, wherein a slide fitting is attached to a lower surface of a seat supporting plate on a front portion thereof so as t be slidable almost horizontally with respect to a flange which is provided on a front part of said supporting lever.

Claim 12

A chair, and comprising, a forward facing base frame fixedly mounted to an upper end of a pillar, a lower part of a supporting lever provided with a back rest movably and rotatably pivotably mounted on a lower rear part of said base frame by a shaft extending from one side of said chair to another side thereof, a seat including in succession a front seat portion and rear seat portion flexibly coupled together through a flexing part adjacent the center of said seat between the front and rear seat portions and being coupled to said supporting lever so as to be able to cooperate with said supporting lever, said front seat portion being locked to a front part of said base frame so as to prevent inclining movement thereof but allowing movement thereof only back and forth, and a return spring for making said supporting lever stand up, between said supporting lever and said base frame.

Claim 13

A chair, and comprising, a forward facing base frame fixedly mounted to an upper end of a pillar, a lower part of a supporting lever provided with a back rest movably and rotatably pivotably mounted on a lower rear part of said base frame by a shaft extending from one side of said chair to another side thereof, a seat including in succession a front seat portion and rear seat portion flexibly coupled together through a flexing part adjacent the center of said seat between the front and rear seat portions and being coupled to said supporting lever so as to be able to cooperate with said supporting lever, said front seat portion being locked to a front part of said base frame so as to prevent inclining movement thereof but allowing movement thereof only back and forth, and a return spring for making said supporting lever stand up, between said supporting lever and said base frame.

Claim 14

A chair according to claim 11, wherein an almost center part of a seat supporting plate is provided on a back surface of said seat and constitutes a flexible part.

Claim 15

A chair according to claim 12, wherein a rear seat support is attached to a lower surface of the seat supporting plate on a rear portion thereof and said rear seat support is pivotably mounted on said supporting lever.

Claim 16

A chair according to claim 13, wherein said rear seat portion is constructed so as to cooperate with said supporting lever and is centered on an axis which is coaxial with said supporting lever.

Claim 17

A chair according to claim 11, wherein said rear seat portion is constructed so as to be able to cooperate with said supporting lever and is centered on an axis which is coaxial with said supporting lever.

Claim 18

A chair according to claim 11, wherein a slide fitting is attached to a lower surface of said sat supporting plate on a front portion thereof so as to be slidable almost horizontally with respect to a flange which is provided on a front part of said supporting lever.

Claim 19

A chair, and comprising, a forward facing base frame fixedly mounted to an upper end of a pillar, a lower part of a supporting lever provided with a back rest movably and rotatably pivotably mounted on a lower rear part of said base frame by a shaft extending from one side of said chair to another side thereof, a seat including in succession a front seat portion and a rear seat portion flexibly coupled together by a flexing part adjacent the center of said seat between the front and rear seat portions, said flexing part being coupled to said supporting lever so as to be able to cooperate with said supporting lever, one end of a gas spring pivotably mounted on a rear part of said base frame and another end thereof pivotably mounted on the frame of said front seat portion, a lever for opening and closing a push valve of said gas spring, and wherein said front seat portion is locked to a front part of said base frame so as to prevent inclining movement thereof but permitting, movement thereof only back and forth.

Claim 20

A chair, and comprising, a forward facing base frame fixedly mounted to an upper end of a pillar, a lower part of a supporting lever provided with a back rest movably and rotatably pivotably mounted on a lower rear part of said base frame by a shaft extending from one side of said chair to another side thereof, a seat including in succession a front seat portion and a rear seat portion flexibly coupled together by a flexing part adjacent the center of said seat between the front and rear seat portions, said flexing part being coupled to said supporting lever so as to be able to cooperate with said supporting lever, one end of a gas spring pivotably mounted on a rear part of said base frame and another end thereof pivotably mounted on the frame of said front seat portion, a lever for opening and closing a push valve of said gas spring, and wherein said front seat portion is locked to a front part of said base frame so as to prevent inclining movement thereof but permitting, movement thereof only back and forth.

Claim 21

A chair according to claim 17, and further comprising a coupling rod bridged between a shaft for pivotably supporting said gas spring and said front seat portion, and a shaft for pivotally supporting said supporting lever and said rear seat portion.

Claim 22

A chair according t claim 17 wherein an almost center part of a seat supporting plate is provided on a back surface of said seat and constitutes a flexible part.

Claim 23

A chair according to claim 19, wherein a rear seat support is attached to a lower surface of the seat supporting plate on a rear portion thereof and said rear seat support is pivotably mounted on said supporting lever.

Claim 24

A chair according to claim 20, wherein said rear seat portion is constructed so as to cooperate with said supporting lever and is centered on an axis which is coaxial with said supporting lever.

Claim 25

A chair according to claim 17, wherein said rear seat portion is constructed so as to be able to cooperate with said supporting lever and is centered on an axis which is coaxial with said supporting lever.

Claim 26

A chair according to claim 17, wherein a slide fitting is attached to a lower surface of aid seat supporting plate on a front portion thereof so as to be slidable almost horizontally with respect to a flange which is provided on a front part of said supporting lever.