Chair for use in dentistry

Claim 2

An odontological chair having a fixed base, raisable seat supported on the base, means varying the height of the seat relative to the base, a variable tilt backrest pivotally connect the rear end of the seat, and means varying the tilt of the backrest to the seat, wherein: the raisable seat comprises a support structure, a seat frame carried by the support structure and movable longitudinally thereon, and seat padding carried by said seat frame; ii. the backrest comprises a backrest frame; backrest padding carried by the frame; backrest supports on which the backrest frame is longitudinally slidable, and means pivotally connecting the support members to the rear of the seat support structure, and including iii. means controling the movement of the seat frame, the backrest supports and the backrest frame and inducing, upon pivotal movement of the backrest supports relative to the seat, longitudinal sliding movement of the backrest frame on the backrest supports and of the seat frame in opposite directions and by different amounts, whereby the said frames are moved together upon lowering of the backrest relative to the seat, and are moved apart upon raising of the backrest relatively to the seat.

Claim 3

An odontological chair having a fixed base, raisable seat supported on the base, means varying the height of the seat relative to the base, a variable tilt backrest pivotally connect the rear end of the seat, and means varying the tilt of the backrest to the seat, wherein: the raisable seat comprises a support structure, a seat frame carried by the support structure and movable longitudinally thereon, and seat padding carried by said seat frame; ii. the backrest comprises a backrest frame; backrest padding carried by the frame; backrest supports on which the backrest frame is longitudinally slidable, and means pivotally connecting the support members to the rear of the seat support structure, and including iii. means controling the movement of the seat frame, the backrest supports and the backrest frame and inducing, upon pivotal movement of the backrest supports relative to the seat, longitudinal sliding movement of the backrest frame on the backrest supports and of the seat frame in opposite directions and by different amounts, whereby the said frames are moved together upon lowering of the backrest relative to the seat, and are moved apart upon raising of the backrest relatively to the seat.

Claim 4

An odontological chair having a fixed base, raisable seat supported on the base, means varying the height of the seat relative to the base, a variable tilt backrest pivotally connect the rear end of the seat, and means varying the tilt of the backrest to the seat, wherein: the raisable seat comprises a support structure, a seat frame carried by the support structure and movable longitudinally thereon, and seat padding carried by said seat frame; ii. the backrest comprises a backrest frame; backrest padding carried by the frame; backrest supports on which the backrest frame is longitudinally slidable, and means pivotally connecting the support members to the rear of the seat support structure, and including iii. means controling the movement of the seat frame, the backrest supports and the backrest frame and inducing, upon pivotal movement of the backrest supports relative to the seat, longitudinal sliding movement of the backrest frame on the backrest supports and of the seat frame in opposite directions and by different amounts, whereby the said frames are moved together upon lowering of the backrest relative to the seat, and are moved apart upon raising of the backrest relatively to the seat.

Claim 5

The chair defined in claim 1, wherein the means controlling the movement of the seat and backrest frame comprise a screw having a rear portion and a front portion of shorter pitch than, and opposite hand to, the rear portion, first and second nuts co-operating with said two screw portions, hinged backrest supports, a linkage connecting the first nut to the hinged backrest support to control the angle of tilt of the backrest, means connecting the second nut to the seat frame to control the longitudinal movement of the latter, and stays connecting the first nut to the movable backrest frame to control longitudinal movements of the backrest frame along said backrest supports in opposition to the longitudinal movements of the seat frame.

Claim 6

The chair defined in claim 1, wherein the means varying the height of the seat include two pairs of levers arranged in a pantograph linkage, nuts carried by said linkage, a central control screw co-operating with said nuts, and electric drive means connected to the screw to rotate the latter.

Claim 7

The chair defined in claim 3, wherein adjoining pairs of levers of the pantograph linkage are provided with toothed sectors meshing with each other to assist stabilization of the linkage. 5. The chair defined in claim 1, and further comprising: i. a raisable fixed part of the seat; ii. a fixed cross piece supported by the raisable part; iii. a fixed nut and two parallel longitudinally extending support members carried by the cross piece; iv. two longitudinal members forming part of the seat support structure and mounted on the said longitudinally extending support members for movement longitudinally relative thereto; v. a longitudinal screw supported by the longitudinal members and having a center portion of relatively long pitch with which the fixed nut is engaged, a front portion of relatively short pitch, of the same screw direction as the center portion, and a rear portion, of intermediate pitch, of the opposite screw direction to the front and central portions; vi. two longitudinal guide rods guiding relative movement of the longitudinal members and supporting the seat frame; vii. a lower transverse member interconnecting said guide rods; viii. a second nut carried by said transverse member, and engaging the front screw portion; ix. a movable cross member carrying a third nut co-operating with the rear screw portion; x. two links articulated to the movable cross member and controlling the slope of the backrest frame and xi. two curved stays articulated to the movable cross-member and controlling the longitudinal sliding movement of the backrest frame, whereby rotation of the screw causes the backrest, variation of the distance between the movable seat and backrest frames, and horizontal movement of the whole seat support structure such as effectively to annul any horizontal displacement of the vertical projection of a patient''s head when rested on the backrest.