Ergonomic chair

A chair comprising:

• support frame means having a forward first support portion and a rear second support portion;
• a seat member pivotably connected at its forward end to said first forward support portion of said frame means and having a rear support portion;
• a backrest member having first and second pivot locations, said first pivot location of said backrest member being pivotably connected to said rear second support portion of said frame means, said backrest member comprising a fabric of elastic material disposed in a carrier mounted on a skeletal back assembly to provide a support which generally conforms to the back of a user when the chair is in any tilt position;
• and
• a link member pivotably connected to said rear support portion of said seat member and pivotably connected to said second pivot location of said backrest member;
• wherein tilting movement of said backrest member rearwardly relative to said frame means causes elevation of said rear portion of said seat member upon weight shifting of the chair user and wherein said seat member and said backrest member have a relative center of rotation approximately coincident with the center of rotation of the hip joint of the user.

A chair comprising:

• support frame means having a forward first support portion and a rear second support portion;
• a seat member pivotably connected at its forward end to said first forward support portion of said frame means and having a rear support portion, said seat member including a cushion portion which is independently movable in a relatively horizontal direction relative to said backrest member, whereby a user may configure said seat member in a desired position relative to said back member for greater comfort;
• a backrest member having first and second pivot locations, said first pivot location of said backrest member being pivotably connected to said rear second support portion of said frame means;
• and
• a link member pivotably connected to said rear support portion of said seat member and pivotably connected to said second pivot location of said backrest member;
• wherein tilting movement of said backrest member rearwardly relative to said frame means causes elevation of said rear portion of said seat member upon weight shifting of the chair user and wherein said seat member and said backrest member have a relative center of rotation approximately coincident with the center of rotation of the hip joint of the user.

A chair comprising:

• support frame means having a forward first support portion and a rear second support portion, said support frame means comprising a transverse central support module, a pair of spaced forwardly extending seat support means carried by said central module and a pair of spaced rearwardly extending backrest support means carried by said module;
• and
• a seat member pivotably connected at its forward end to said first forward support portion of said frame means and having a rear support portion;
• a backrest member having first and second pivot locations, said first pivot location of said backrest member being pivotably connected to said rear second support portion of said frame means;
• and
• a link member pivotably connected to said rear support portion of said seat member and pivotably connected to said second pivot location of said backrest member;
• wherein tilting movement of said backrest member rearwardly relative to said frame means causes elevation of said rear portion of said seat member upon weight shifting of the chair user and wherein said seat member and said backrest member have a relative center of rotation approximately coincident with the center of rotation of the hip joint of the user.

A chair comprising:

• support frame means having a forward first support portion and a rear second support portion;
• a seat member pivotably connected at its forward end to said first forward support portion of said frame means and having a rear support portion;
• a backrest member having first and second pivot locations, said first pivot location of said backrest member being pivotably connected to said rear second support portion of said frame means;
• a link member pivotably connected to said rear support portion of said seat member and pivotably connected to said second pivot location of said backrest member;
• and
• a pair of armrests on opposite sides of said seat member, said armrests being height adjustable;
• wherein tilting movement of said backrest member rearwardly relative to said frame means causes elevation of said rear portion of said seat member upon weight shifting of the chair user and wherein said seat member and said backrest member have a relative center of rotation approximately coincident with the center of rotation of the hip joint of the user.

A chair comprising:

• support frame means having a forward first support portion and a rear second support portion;
• a seat member pivotably connected at its forward end to said first forward support portion of said frame means and having a rear support portion;
• a backrest member having first and second pivot locations, said first pivot location of said backrest member being pivotably connected to said rear second support portion of said frame means;
• a link member pivotably connected to said rear support portion of said seat member and pivotably connected to said second pivot location of said backrest member;
• and
• at least one extension spring connected between said rear support portion of said seat member and said backrest member, thereby to urge said backrest toward an upright position;
• wherein tilting movement of said backrest member rearwardly relative to said frame means causes elevation of said rear portion of said seat member upon weight shifting of the chair user and wherein said seat member and said backrest member have a relative center of rotation approximately coincident with the center of rotation of the hip joint of the user.

A tiltable chair comprising:

• a base member;
• a seat member, said seat member including a cushion comprising an assembly of a rigid seat pan, a foam layer, a plurality of spaced foam risers defining a plenum, an elastomeric member overlying said risers, an air permeable layer overlying said elastomeric layer, and a fabric covering said layers;
• a backrest member;
• and
• a linkage assembly connecting said seat member and said back member to said base member, said linkage assembly being configured and arranged to allow a rear portion of said seat to rise and concurrently said back member to tilt downwardly and rearwardly, with pivotal movement of said seat member relative to said back member occurring about a pivot axis substantially in alignment with the hip joints of a user.

A tiltable chair comprising:

• a base member;
• a seat member;
• a backrest member;
• a pair of armrest assemblies disposed on said base member on opposite sides of said seat member, said armrest assemblies remaining in substantially the same attitude regardless of the angle of inclination of said back member or said seat member during tilting of said chair;
• and
• a linkage assembly connecting said seat member and said back member to said base member, said linkage assembly being configured and arranged to allow a rear portion of said seat to rise and concurrently said back member to tilt downwardly and rearwardly, with pivotal movement of said seat member relative to said back member occurring about a pivot axis substantially in alignment with the hip joints of a user.

A tiltable chair comprising:

• a base member;
• a seat member;
• a backrest member, said backrest member comprising a skeletal frame having a carrier affixed thereto, said carrier having a fabric disposed therein for contact with the back of the user;
• and
• a linkage assembly connecting said seat member and said back member to said base member, said linkage assembly being configured and arranged to allow a rear portion of said seat to rise and concurrently said back member to tilt downwardly and rearwardly, with pivotal movement of said seat member relative to said back member occurring about a pivot axis substantially in alignment with the hip joints of a user.

A tiltable chair comprising:

• a base member;
• a seat member;
• a backrest member;
• a height adjustable lumbar member positioned horizontally across said back member at approximately the lumbar region of a back of a user, said lumbar member being height adjustable by the user;
• and
• a linkage assembly connecting said seat member and said back member to said base member, said linkage assembly being configured and arranged to allow a rear portion of said seat to rise and concurrently said back member to tilt downwardly and rearwardly, with pivotal movement of said seat member relative to said back member occurring about a pivot axis substantially in alignment with the hip joints of a user.

A tiltable chair comprising:

• a base member;
• a seat member;
• a backrest member;
• adjustable tilt limiting means whereby the user may selectively predetermine the maximum amount of inclination of said chair back;
• and
• a linkage assembly connecting said seat member and said back member to said base member, said linkage assembly being configured and arranged to allow a rear portion of said seat to rise and concurrently said back member to tilt downwardly and rearwardly, with pivotal movement of said seat member relative to said back member occurring about a pivot axis substantially in alignment with the hip joints of a user.