Patent ID: 7513569

Claim:
A synchronous office chair, comprising: a) a support firmly connected to a supporting column; b) a seat base articulated on a tilting axis on said support, said tilting axis disposed at a front area of said seat base and extending in a direction across a width of said seat base; c) a flange firmly connected to said seat base; d) a backrest and a back bracket firmly connected with said backrest, said back bracket engaging in an interstice between said support and said seat base and said flange engaging in said back bracket, wherein said seat base with said flange and said backrest with said back bracket are formed to execute a synchronous movement, said back bracket comprising: i) a first cam track; ii) a second cam track positioned forward of said first cam track; and iii) a third cam track positioned forward of said second cam track; e) a first roller bearing mounted on said flange, said first rolled bearing engaging in said first cam track, wherein the synchronous movement of the synchronous office chair is guided in said first cam track; f) a second roller bearing mounted on said seat base, said second roller bearing engaging in said second cam track, wherein the synchronous movement of the synchronous office chair is guided in said second cam track; and g) a third roller bearing mounted on said support, said third roller bearing engaging in said third cam track, wherein the synchronous movement of the office chair is guided in said third cam track; wherein the synchronous movement of the synchronous office chair is formed such that said seat base with said flange executes a first tilting movement about said tilting axis; wherein said backrest with said back bracket executes a second tilting movement about a virtual axis corresponding to a pelvic pivot of a person sitting on the synchronous office chair, said second tilting movement being approximately two to three times as large as said first tilting movement and said backrest with said back bracket executing a translational movement downward and forward at the same time as said second tilting movement; and wherein a pivot point of said second tilting movement about said virtual axis at all times lies essentially at a same distance above a rear middle part of said seat base, such that as the person sitting on the synchronous office chair leans back, a body pivot point of the person and the pivot point of said second tilting movement about said virtual axis remain substantially consistent.