Chair

Abstract

A chair includes: a seat body having a seating surface which provides seating to a user; a support device that supports the seat body such that the seat body is movable along a front-to-rear direction of the chair within a predetermined range; and an urging device. When the seat body is located in an area between a front position and a first reference position, the support device supports the seat body such that the seat body is moved to the front position by own weight. When the seat body is located between a rear position and a second reference position, the urging device urges the seat body toward the front position, whereas, when the seat body is located between the second reference position and the front position, the urging device does not urge the seat body.

1 . A chair comprising:
 a seat body having a seating surface which provides seating to a user;   a support device that supports the seat body such that the seat body is movable along a front-to-rear direction of the chair within a predetermined range; and   an urging device,   wherein, when the seat body is located in an area between a front position, which is a limit in a front side of the predetermined range, and a first reference position, located behind the front position, the support device supports the seat body such that the seat body is moved to the front position by own weight, and   wherein, when the seat body is located between a rear position, which is a limit in a rear side of the predetermined range, and a second reference position located between the first reference position and the front position, the urging device urges the seat body toward the front position, whereas, when the seat body is located between the second reference position and the front position, the urging device does not urge the seat body.   
     
     
         2 . The chair according to  claim 1 ,
 wherein the urging device comprises a pressing portion that comes in contact with and comes away from one of the seat body and a predetermined surface of the support device, and   wherein, when the seat body is located between the rear position and the second reference position, the pressing portion comes in contact with the predetermined surface and presses the predetermined surface so as to urge the seat body toward the front position, and when the seat body is located between the second reference position and the front position, the pressing portion comes away from the predetermined surface so as not to urge the seat body.   
     
     
         3 . The chair according to  claim 1  further comprising a shock-absorbing device that restricts moving speed of the seat body toward the front position. 
     
     
         4 . The chair according to  claim 3 , wherein the shock-absorbing device restricts the moving speed of the seat body toward the front position, only when the seat body is located in an area between the second reference position and the front position. 
     
     
         5 . The chair according to  claim 1 , wherein the support device comprises:
 a leg support installed on a floor surface; and   a swing portion that supports the seat body and has one end thereof connected to the leg support so as to be swingable in the front-to-rear direction around where the one end is connected.   
     
     
         6 . The chair according to  claim 1 , wherein the urging device is a gas spring. 
     
     
         7 . The chair according to  claim 1 ,
 wherein the urging device is a gas spring,   wherein the support device comprises: a leg support installed on a floor surface; and a swing portion that supports the seat body and has one end thereof connected to the leg support so as to be swingable in the front-to-rear direction around where the one end is connected,   wherein the chair further comprises a link arm having: one end connected to one end of the gas spring via a first rotational shaft so as to be rotatable around the first rotational shaft; and another end connected to the swing portion via a second rotational shaft, disposed at a distance from the first rotational shaft, so as to be rotatable around the second rotational shaft,   wherein another end of the gas spring is connected to a third rotational shaft, disposed in a position in which a distance from the second rotational shaft changes corresponding to movement of the seat body, so as to be rotatable around the third rotational shaft, and   wherein the gas spring urges the seat body to the front position by one of ways of extending and being compressed, when the seat body is located between the second reference position and the rear position.   
     
     
         8 . The chair according to  claim 7  further comprising a rotary damper disposed on at least one of the first and the second rotational shafts so as to restrict moving speed of the seat body toward the front position. 
     
     
         9 . The chair according to  claim 7 , wherein the swing portion comprises an abutment surface pressed by one of the gas spring and the link arm, when the gas spring extends. 
     
     
         10 . The chair according to  claim 1 ,
 wherein the urging device is a gas spring,   wherein the support device comprises: a leg support installed on a floor surface; and a swing portion having one end thereof connected to the leg support and another end thereof connected to the seat body so as to be swingable around the leg support, and   wherein one end of the gas spring is engaged with an elongate hole, formed on the swing portion, so as to be slidable in the elongate hole, and another end of the gas spring is attached to a rotational shaft, disposed in a position in which a distance from the elongate hole changes corresponding to movement of the seat body, so as to be rotatable around the rotational shaft.