초록 ▼

A housing is fixed on the backrest and supports the same for vertical sliding movement on the upper end portion of a vertical support member. Notches are spaced vertically along the upper portion of the support member and a pawl is pivotally supported on the housing and includes a ratchet finger mov

A housing is fixed on the backrest and supports the same for vertical sliding movement on the upper end portion of a vertical support member. Notches are spaced vertically along the upper portion of the support member and a pawl is pivotally supported on the housing and includes a ratchet finger movable between an operative position with the ratchet finger in engagement with the notches and an inoperative position with the ratchet finger out of engagement with the notches. A spring is associated with the pawl and is operable to selectively maintain the pawl and ratchet finger in either the operative or inoperative positions. When the backrest is raised to the uppermost adjusted position, the pawl; is switched to the inoperative position and the backrest may be freely lowered to the lower end of the adjustment limit in preparation for a subsequent adjustment in the upward direction.

대표청구항 ▼

1. In an office chair including a seat, a vertically extending support member having its lower end secured to said seat, and a backrest supported for vertical adjustment on the upper end portion of said support member, the combination therewith of improved means for adjusting the vertical position o

1. In an office chair including a seat, a vertically extending support member having its lower end secured to said seat, and a backrest supported for vertical adjustment on the upper end portion of said support member, the combination therewith of improved means for adjusting the vertical position of said backrest on said support member, said backrest adjusting means comprising a. a housing fixed on said backrest and supporting said backrest for vertical sliding movement on the upper portion of said support member, b. notch means extending vertically along the upper portion of said support member and including upper and lower ends, c. a pawl pivotally supported on said housing and including ratchet finger means positioned below the pivot point of said pawl, said pawl being movable between an operative position with said ratchet finger means in engagement with said notch means, and an inoperative position with said ratchet finger means out of engagement with said notch means, d. an elongate tension spring with a longitudinal axis and including upper and lower ends, said lower end of said tension spring being connected to said pawl below the pivot point thereof and adjacent said ratchet finger means, said upper end of said tension spring being connected to said housing and above the pivot point of said pawl, and said longitudinal axis of said tension spring being positioned on one side of the pivot point of said pawl when in said operative position and being positioned on the other side of the pivot point of said pawl when in said inoperative position, and e. operator means associated with said upper and lower ends of said notch means for engagement with said pawl, said operator means at the lower end of said notch means being operable to move said pawl into said operative position and maintained in said operative position by said spring axis being positioned on one side of the pawl pivot point when said backrest and said pawl are moved to the lower end of said notch means so that said backrest may be moved to the desired level and maintained in such adjusted position by engagement of said ratchet finger means with said notch means, said operator means at the upper end of said notch means being operable to move said pawl into said inoperative position and maintained in said inoperative position by said spring axis being positioned on the other side of the pawl pivot point when said backrest and said pawl have been moved to the upper end of said notch means so that said backrest may be freely moved to said lower end of said notch means in preparation for making a subsequent vertical adjustment of said backrest. 2. An office chair according to claim 1 wherein said notch means includes a central vertical slot and vertically spaced notches along opposite sides of said vertical slot. 3. An office chair according to claim 2 wherein said ratchet finger means comprises a pair of ratchet fingers, and an operating tongue positioned between and extending outwardly beyond said pair of ratchet fingers, said tongue being positioned to extend into said slot and said ratchet fingers being positioned to engage said vertically spaced notches when said pawl is in said operative position. 4. An office chair according to claim 3 wherein said operator means at said lower end of said notches includes a cam member being engageable by said tongue when said housing is moved to the lower limit to switch said pawl to said operative position. 5. An office chair according to claim 4 wherein said operator means at said upper end of said notches includes a portion of said support members above said slot which is engageable by said tongue when said housing is moved to the upper limit to switch said pawl to said inoperative position. 6. An office chair according to claim 1 wherein said housing includes a front stamped housing plate extending behind said support member, a rear stamped housing plate extending in front of said support member, and means connecting said front and rear housing plates together along opposite side edges thereof, and including slide guide bars supported in said front and rear housing plates and in engagement with opposed side portions of said support member. 7. An office chair according to claim 6 wherein said support member includes a relatively flat central portion with forwardly bent opposite side edges to provide rigidity thereto. 8. In an office chair including a seat, a vertically extending support member having its lower end secured to said seat, and a backrest supported for vertical movement on the upper end portion of said support member, the combination therewith of improved means for adjusting the backrest vertically of said support member, said backrest adjusting means comprising a. a housing fixed on said backrest and supporting said backrest for vertical sliding movement on a medial portion of said support member, b. notch means extending vertically along a medial portion of said support member and including a vertical slot with spaced notches along opposite sides of said slot, c. a pawl pivotally supported on said housing and including a pair of ratchet fingers positioned below the pivot point and being engageable with said notches, said pawl being movable between an operative position with said ratchet fingers in engagement with said notches, and an inoperative position with said ratchet fingers out of engagement with said notches, d. an elongate tension spring attached at one end to said pawl and adjacent said ratchet fingers and at the other end to said housing and above the pivot point of said pawl, the longitudinal axis of said spring extending on one side of the pivot point of said pawl when said pawl is in said operative position to resiliently maintain said ratchet fingers in engagement with said notches, said spring extending on the opposite side of the pivot point of said pawl when said pawl is in said inoperative position to resiliently maintain said ratchet fingers out of engagement with said notches, and e. operator means at the upper and lower ends of said notches for engagement with said pawl, said operator means at said lower end of said notches being operable to move said pawl into said operative position and maintained in said operative position by said spring axis being positioned on one side of the pawl pivot point when said backrest and said pawl are moved to the lower end of said notches so that said backrest may be raised to the desired level and maintained in adjusted position by engagement of said ratchet fingers with said notches, said operator means at said upper end of said notch means being operable to move said pawl into said inoperative position and maintained in said inoperative position by said spring axis being positioned on the other side of the pawl pivot point when said backrest and said pawl have been moved to the upper end of said notches so that said backrest may be freely moved to its lowermost position in preparation for making a subsequent vertical adjustment of said backrest. 9. Vertical height adjustment means for adjusting the vertical position of a vertically adjustable member supported for vertical movement on the upper end portion of an upstanding support of a fixed base member, said vertical height adjustment means comprising a. a housing fixed on said vertically adjustable member, said housing surrounding and supported for vertical sliding movement on the upper portion of said upstanding support, b. notch means extending vertically along the upper portion of said upstanding support and including upper and lower ends, said notch means including a central vertical slot and vertically spaced notches along opposite sides of said vertical slot, c. a pawl pivotally supported on said housing and including ratchet finger means at one end thereof, said ratchet finger means including a pair of ratchet fingers, and an operating tongue positioned between and extending outwardly beyond said pair of ratchet fingers, said pawl being movable between an operative position with said pair of ratchet fingers in engagement with said vertically spaced notches, and an inoperative position with said pair of ratchet fingers out of engagement with said vertically spaced notches, d. over center spring means operatively associated with said pawl and being operative along a line of action to selectively maintain said ratchet finger means in said operative position with said ratchet finger means in resilient engagement with said notch means, or in said inoperative position with said ratchet finger means out of engagement with said notch means, the line of action of said over center spring means being positioned on one side of the pawl pivot point when in said operative position and being positioned on the other side of the pawl pivot point when in said inoperative position, and e. operator means associated with said upper and lower ends of said notch means for engagement with said pawl, said operator means at the lower end of said notch means being operable to move said pawl into said operative position when said vertically adjustable member and said pawl are moved to the lower end of said notch means so that said vertically adjustable member may be moved to the desired level and maintained in such adjusted position by engagement of said ratchet finger means with said notch means, said operator means at the upper end of said notch means being operable to move said pawl into said inoperative position when said vertically adjustable member and said pawl have been moved to the upper end of said notch means so that said vertically adjustable member may be freely moved to said upper end of said notch means in preparation for making a subsequent vertical adjustment of said vertically adjustable member. 10. Vertical height adjustment means according to claim 9 wherein said operator means at said lower end of said notches includes a cam member being engageable by said tongue when said housing is moved to the lower limit to switch said pawl to said operative position and to limit downward movement of said vertically adjustable member. 11. Vertical height adjustment means according to claim 10 including stop means carried by and extending inwardly from the lower portion of said housing and beneath said cam member, said stop means being engageable with said cam member to limit upward movement of said vertically adjustable member.