Chair for dental patients

Abstract

A chair for dental patients has a lower portion and an upper portion including a swingable back and a seat movable when the back is swung. The seat is connected at its rear end by a hinge with the lower end of the back. The invention is particularly characterized in that the seat is mounted upon the lower portion so as to be movable in the longitudinal direction of the chair, while the back is guided over a rigid guide which is connected with the lower portion and the back. Means are provided in the part of the seat free from the hinge between it and the lower portion which are operable when the back is swung to tip the seat about a horizontal axis toward the back.

What is claimed is: 
     
       1. A chair for dental patients, comprising a lower portion and an upper portion, said upper portion having a back, a seat, and a hinge connecting the lower end of said back with the rear end of said seat, said upper and lower portions having means for supporting and moving said seat in a longitudinal direction, said means including crosshead .[.guides.]. .Iadd.guide assemblies, .Iaddend.one part of .Iadd.each of .Iaddend.said crosshead .[.guides.]. .Iadd.guide assemblies .Iaddend.being connected with the seat and the other part with the lower portion, .[.the chair.]. .Iadd.said means .Iaddend.having rods with ends connected about a horizontal axis transverse to the longitudinal axis of the chair with said back and other ends connected with said lower portion, .Iadd.at least one of the rods providing an arm support for the chair, .Iaddend.and means interposed between said seat and said lower portion and away from said hinge for tipping said seat about a horizontal axis toward said back when said back is inclined. 
     
     
       2. A chair in accordance with claim 1 wherein the second-mentioned means comprise a curved member and a roller guide engaging said curved member. 
     
     
       3. A chair in accordance with claim 1 wherein the second-mentioned means comprise a supporting arm pivotally connected with said seat and said lower portion. 
     
     
       4. A chair in accordance with claim 2, wherein said curved member is so shaped that the tipping of the seat begins when the back is inclined by more than 25° to the vertical. 
     
     
       5. A chair in accordance with claim 3, wherein said supporting arm is of such length and so connected that the tipping of the seat begins when the back is inclined by more than 25° to the vertical. 
     
     
       6. A chair in accordance with claim 3, .[.comprising.]. .Iadd.wherein the crosshead guide assemblies including .Iaddend.crosshead guides having a horizontal guiding way and .Iadd.being .Iaddend.carried by said lower portion, .Iadd.and .Iaddend.said supporting arm .Iadd.being connected with a crosshead or longitudinal displacement within the guiding ways. .Iaddend. 
     
     
       7. A chair in accordance with claim 3, comprising a common bearing upon said lower portion for said rods and said supporting arm. 
     
     
       8. A chair in accordance with claim 6, .[.comprising.]. .Iadd.wherein said crosshead comprises .Iaddend.a sliding block movable upon said crosshead guides and constituting a bearing for said supporting arm and said rods. 
     
     
       9. A chair in accordance with claim 1, wherein said upper portion comprises a seat part, a leg supporting part and a rotary hinge interconnecting said parts, a curved member carried by said leg supporting part and a roller member carried by said lower portion and engaging said curved member to swing said leg supporting part about said rotary hinge when said seat is moved longitudinally. 
     
     
       10. A chair in accordance with claim 9, wherein said curved member is adjustable. .[.11. A chair in accordance with claim 1, comprising a rotary drive for inclining said back and having a driving axle coinciding with 
     
     
        the connection of said rods with said back..]. 12. A chair in accordance with claim 1, wherein said rods .[.constitute arm supports,.]. .Iadd.includes .Iaddend.cardan joints connecting said rods with said back 
     
     
        and said lower portion. 13. A chair in accordance with claim 1, wherein said .Iadd.crosshead guide assemblies include .Iaddend.crosshead guides having sliding bearings.