Headrest For An Ophthalmic Chair Or The Like

Abstract

A spring mounted linkage system adjustably supporting a headrest characterized by a single reciprocally movable knob uniquely capable of locking the headrest in various positons.

Description

BACKGROUND OF THE INVENTION

A variety of adjustable support systems and linkages are available for supporting headrests of the type found on various physicians chairs. For example, chairs of the type used by an ophthalmologist, a dentist, or others rendering medical or like services for a patient in a semi-reclined, yet seated position.

It is desirable that such linkage systems allow for easy positive adjustment to a plurality of positions. The present invention provides a bracket, link and arm support arrangement which is unique in the manner in which the various parts are locked into position. The arrangement allows for rapid and easy, yet accurate and positive positioning of the headrest in a plurality of positions.

OBJECTS OF THE INVENTION

It is a primary object of this invention to provide a chair headrest of an improved type. It is another object of the invention to provide a headrest linkage system of the bracket, link and arm type characterized by a unique position locking arrangement.

DRAWING

FIG. 1 is a side elevation in partial section of a bracket, link and arm headrest construction according to this invention.

FIG. 2 is a top elevation of a portion of the arrangement of FIG. 1 in partial section.

FIG. 3 is a partial section along the line A--A of FIG. 1 indicating the internal cooperation between parts associated with a single control knob.

FIG. 4 is a fragmentary section of a group of the elements associated with the control knob of FIG. 3.

FIG. 5 is a fragment of the headrest locking pivot in partial section.

DESCRIPTION OF THE INVENTION

In FIG. 1 there is shown a bracket, link and arm headrest construction including an arm 10 interconnected between a headrest 11, held in a bracket 11' and an elongated link 12 by a splined bearing 13. The opposite end of the link 12 is connected through an additional splined bearing 14 to a chair support 15. The chair support 15 is connected to the back of a chair in a conventional manner by attaching the plate 16 to the back of a chair with bolts or screws inserted through the plurality of bolt holes 17. An exemplary chair indicating the relative position of a headrest of the type shown herein can be found, for example, in U.S. Pat. No. 2,672,917.

The headrest 11 is attached to the arm 10 by a suitable pivot screw 20. The screw 20 is spring loaded and easily adjusted in a conventional manner. As can be seen by reference to FIG. 5, a spring loaded support 21 has a central annular aperture through which extends the screw 20 to threadily engage the annular nut member 22. A spring washer 23 assures friction.

Referring again to FIG. 1, the link 12 is hollow in that a pair of substantially identical shafts 25 and 25' are arranged for reciprocal axial movement through the respective axial passages 26 and 26' against the splined bearings 13 and 14. Those end portions of the shafts 25 and 25' bearing against the splined bearings 13 and 14 have teeth arranged to substantially coincidentally move into and out of locking registry with the splines of the bearings under the influence of cam member 50 and springs 30, respectively. Referring for the moment to FIG. 2, there is preferably found a pair of springs 30' and 30 suitably fastened by screws 35, 36, 37, and 38. As shown in FIG. 2, the spring 30' is fastened to the body of the link 12 by the screw 35 and its other end by the screw 37 to the shaft 25. Note the screw 37 is able to reciprocally move axially of the link 12 in the groove 40.

Spring 30 is similarly fastened by the screw 38 and screw 36 axially movable in the groove 41. Referring for the moment to FIG. 4, the adjacent or opposed ends of the shafts 25 and 25' are tapered and rest on opposite sides of the generally truncated conical base portion of the cam member 50. The member 50 is urged back and forth on an axis normal to the axis on which the shafts 25 and 25' move. This motion of member 50 is induced by turning the knob 51. Note the knob 51 is fastened by a set screw 52 to the threaded shaft 53. The truncated conical portion of the member 50 terminates in a plate-like device 60. This device 60 prevents the knob 51 and associated parts from accidentally being unscrewed sufficiently to be disengaged since the plate 60 is held between the opposed tapered ends of the shafts 25 and 25' when the threaded shaft 53 is disengaged.

Recapitulating: a pair of splined bearings 13 and 14 which are locked in place with suitable set screws 70 to the arm 10 and chair support 15 are free to rotate in the ends of connecting member or link 12. However, the connecting member or link 12 contains a knob 51 which, together with suitable springs and cam or bearing devices, causes a pair of shafts 25 and 25' having toothed ends to move into and out of association with the complimentary splines which extend axially about the outer peripheral surface of the bearings 13 and 14.

As knob 51 is threaded outwardly or retracted, the springs 30 and 30' pull the shafts 25 and 25' together along the opposed surfaces of the truncated conical cam member 50. This allows both bearings and associated element 10 to rotate freely to move the arrangement as shown, for example to the dotted or dashed line position 100. Rotating the knob 51 in the opposite direction causes the conical base of cam member 50 to force apart the opposed shafts 25 and 25' into locking association with the bearings 13 and 14.

One additional element is worthy of note. A screw 75 (see FIG. 3) interconnects the member 50 with a threaded shaft 53 through an oversized aperture 76. This allows the taper of the member 50 to take up variation in the lengths of the shafts 25 and 25'.

Having thus described the invention in detail and with sufficient particularity as to enable one skilled in the art to practice the invention, what is desired to have protected by Letters Patent is set forth in the following claims:

Claims

What is claimed is:

1. An adjustable headrest support linkage system of the bracket, link and arm type comprising: head support means carried adjacent one end of an elongated arm, the arm pivotally interconnected with an intermediate link by a bearing, the bearing being fixed relative to the arm, the bearing pivotally associating an end portion of the arm with an intermediate link, there being a split shaft associated with the link and arranged to move axially thereof, an additional bearing pivotally associated with the other end of the link and with chair support structure, said additional bearing being fixed relative to the chair support structure, locking means carried by the link intermediate its ends in position to reciprocally move the split portions axially of the link so that opposed ends thereof are substantially coincidentally moved into association with the bearings, there being means on said opposed ends of the split shaft arranged for locking the bearings in position upon appropriate adjustment of the locking means.

2. The arrangement of claim 1 in which said bearings are splined and in which the opposed ends of the split shaft have serrations arranged to mate with the splines on the bearings to lock the head support means in position.

3. The arrangement of claim 1 further including spring means operatively interconnected between the link and the portions of the split shaft arranged to urge the split shaft elements out of locking association with the bearings upon appropriate movement of the locking means.

4. The arrangement of claim 1 in which said locking means is comprised of an externally accessible knob having depending therefrom a threaded shaft arranged to mate with complementary threads in the link whereby the knob is moved into and out of engagement with said link, there being additional means depending axially from the threaded shaft, said additional means including cam surfaces arranged to cooperate with opposed ends of the split portions of the shaft whereby, upon threading and unthreading of the knob, the cam surfaces move the shaft portion into and out of locking association with the bearings.