GB2169501A

GB2169501A - Backrest guide mechanism

Info

Publication number: GB2169501A
Application number: GB08431217A
Authority: GB
Inventors: Kenneth Crisp
Original assignee: ELLISON HOSPITAL EQUIPMENT LIM
Current assignee: ELLISON HOSPITAL EQUIPMENT LIM
Priority date: 1984-12-11
Filing date: 1984-12-11
Publication date: 1986-07-16
Also published as: GB2169501B; GB8431217D0

Abstract

A hospital bed backrest which is moved automatically into an inclined position as its upper part is moved downwards on two vertical posts (20 and 22) forming part of the head-bow (24) of the bed. A strut (46) having yielding characteristics extends between a mid-portion of the backrest and a part of the head-bow (24) or bed frame to bring the lower end of the backrest into an initial position where it lies just above a mattress (54) on the bed. When, however, a patient on the bed rests his or her back on the backrest, then the lower part of the backrest will be pushed downwards under the weight of the patient into bearing contact with the mattress. This is achieved by making the strut (46) of telescopic construction with a helical spring (56) in one of the two telescopic members (58 and 60) forming the strut serving to urge the strut resiliently into an extended state. <IMAGE>

Description

SPECIFICATION Backrest guide mechanism This invention relates to backrest guide mechanisms for guiding the movement of backrests carried by the head-bows of hospital beds.

It is usual to provide hospital beds with a tubular steel head-bow having two or more vertical posts on which a tubular frame backrest is adjustably supported. The upper part of the backrest is provided with some kind of locking mechanism which locks onto one or both of the vertical posts at different positions along the latter so as to permit the backrest to take up any position between a sub stantiallyvertical position and a substantially horizontal position simply by moving the upper part of the backrest up or down on the vertical posts.

It has already been proposed to provide a pair of struts between mid-portions of a backrest and a lower part of the head-bow so that the lower part of the backrest is moved towards the foot of the bed as the upper part of the backrest is moved downwardly. In other words, the struts serve to guide movement of the backrest in such a way that it automatically takes up an inclined position as the upper part of the backrest is moved downwards.

However, this form of construction has the disadvantage that the lower part of the backrest cam jam on the mattress of the bed or, alternatively, will take up a'fixed position where it lies above and clear of the mattress on the bed, and it is then impossible to push the lower part of the backrest down into contact with the mattress because of the rigid nature of the guide struts.

The aim of the present invention is to use something similar to the strut arrangement described above but with an improved form of strut which allows the lower part of the backrest to be brought into bearing contact with the mattress in a resilient manner.

With this aim in view, the present invention is directed to a backrest which is guided as its upper part is moved downwardly by one or more struts or other guide means which are able to yield or reduce in length in such a way that the lower part of the backrest can be brought into a position where it lies just above a mattress on a hospital bed, from which position it can then be brought into bearing contact with the mattress under the weight of a patient in the bed.

In one form of construction, the strut, or each strut, is of telescopic form with a spring in one of the telescopic members serving to extend the strut. It is however possible for some otherform of yielding strut to be provided. It could for example comprise a leaf spring which yields under the weight of a patient on the backrest to bring the lower end of the backrest into bearing contact with the mattress.

An example of backrest guide mechanism in accordance with the invention is shown in the accompanying drawings, in which: Figure lisa front view of the backrest mounted on a head-bow of a medical bed; Figure 2 is an enlarged sectional view through the upper part of the backrest; Figure 3 is a still larger section through the middle portion of a lock box shown in Figure 2; and Figure 4 is a side view of the backrest and headbow of the bed.

The backrest shown in the drawings comprises a tubular metal frame 10 having three horizontal cross struts 12 which are likewise of tubular metal. The backrest incorporates a locking mechanism in a loek box 14 comprising a hollow casing having sleeve openings 16 and 18 (see Figure 2) in the upper and lower surfaces of the casing so as to permit the latter to slide on two vertical posts 20 and 22 forming i:art of a head-bow 24 of a medical bed. As shown in Figure 2, the locking mechanism in the lock box 14 comprises two floating levers 26 arranged in V formation and each provided with a hole 28 through which the post 20 passes. The rear portions of the two levers 26 associated with each post are tied together by a springy clip 30.This serves to lock the levers on to the post 20, thereby preventing movement of the backrest along the two posts 20 and 22.

A sliding bolt or shaft 32 with a rounded front end 34 is urged by a helical spring 36 into a position where the rounded end is clear of the adjacent rear ends of the two levers 26 shown in Figure 2. When, however, a button 38 projecting from the lock box 14 is depressed in the direction of the arrow 'X' shown in Figure 3, the lower surface of the button moves a cam 40 in the lock box into a position where it displaces the slide rod 32 in a longitudinal direction so as to force the end portions of the levers 26 apart against the action of the springy clip 30.

This has the effect of bringing the two levers 26 into a position where they are more or less parallel to each other, with the result that their locking grip on the post 20 is released. It is now therefore possible for the backrest to be moved along the posts 20 and 22.

When the button 38 is released, a spring 42 acts on the cam 40 so as to restore the latter to its original position of rest. This allows the slide rod 32 to return to its original position where its nose 34 is clear of the levers 26. The said levers therefore return to their locking position, under the action of the springy clip 30, so that the backrest is locked onto the two posts 20 and 22.

Figure 1 shows the backrest in its uppermost position on the head-bow 24 with the backrest lying substantially in the plane of the head-bow. If now the button 38 is depressed so as to release the locking mechanism described above, the upper part of the backrest is able to move downwards along the vertical posts 20 and 22. Simultaneously, the lower part 44 of the backrest is pushed rearwards in the direction of the foot of the bed, i.e., in the direction ofthearrow'Y'shown in Figure 4, buy a strut 46 which is pivotally connected at 48 to the mid-strut 12a of the backrest with the lower end of the strut 46 being pivotally connected at 50 to a fixed member 52 forming part of the head-bow.

Alternatively, the lower end of the strut 46 could be pivotally connected to the head-bow itself or, if desired, to a rigid part of the bed frame.

It thus follows that, as illustrated by broken lines in Figure 4, the backrest is moved automatically into an inclined position as its upper part is moved downwards on the posts 20 and 22. However, the lower end 44 of the backrest is not held in a fixed position by the strut 46. This is because the strut 46 has yielding characteristics which therefore permit the lower end 44 of the backrestto be brought initially into a position where it lies just above the mattress 54 on the bed. Thus, it will be seen from Figure 4 that the lower end 44 of the backrest is actually held clear of the mattress by a small distance when the backrest is brought into an inclined position by the strut 46.When, however, a patient on the bed rests his or her back on the backrest, then the lower part 44 of the backrest will be pushed downwards under the weight of the patient into bearing contact with the mattress. This is achieved by making the strut 46 of telescopic construction with a helical spring 56 being arranged in one of the two telescopic members 58 and 60 forming the strut so asto urge the strut resiliently into an extended state.

The backrest guide mechanism shown in the drawings comprises a single strutwhich is mounted centrally of the backrnst It is however equally possible for two or more struts to be provided and for these to be arranged otherthan centrally of the backrest. Further, it is not necessary for the strut to be of telescopic form, as a strut of variable length or of leaf spring construction could also be used to achieve the same effect.

When it is desired to move the backrest into a vertical position from the inclined position shown in broken lines in Figure 4, the button 38 is depressed to release the locking mechanism in the lock box 14 and the upper part of the backrest is lifted along the guide posts 20 and 22. The strut 46 will then cause the remainder of the backrestto return to a position where it lies substantially in the plane of the headbow.

Claims

1. A hospital bed backrest which is guided as its upper part is moved downwardly on the head-bow of a hospital bed by one or more struts or other guide means which are able to yield or reduce in length in such a way that the lower part of the backrest can be brought into a position where it lies just above a mattress on the bed, from which position the lower part of the backrest can then be brought into bearing contact with the mattress under the weight of a patient in the bed.

2. A hospital bed backrest according to claim 1, in which the strut, or each strut, is of telescopic form with a spring in one ofthetelescopic members serving to extend the strut.

3. A hospital bed backrest according to claim 1, in which the strut, or each strut, comprises a leaf spring which yields under the weight of a patient on the backrest to bring the lower end of the backrest into bearing contact with the mattress.

4. A hospital bed backrest according to claim 1 or claim 2, in which the lower part of the backrest is pushed rearwards in the direction of the foot of the bed by the strut or struts when the upper part of the backrest is moved downwards, the strut, or each strut, being pivotally connected at one end to a midportion of the backrest with the other end of the strut being pivotally connected to the head-bow, or to a fixed member on the head-bow, orto a rigid part of the bed frame.

5. A hospital bed backrest according to any preceding claim comprising a tubular metal frame having a plurality of horizontal cross-struts which are likewise oftubular metal, the backrest being provided with a locking mechanism in a hollow casing having openings in its upper and lower surfaces to permit the latter to slide on two vertical posts forming part of the head-bow of the bed, the locking mechanism being in the form of two fioating levers arranged in V formation and each provided with a hole through which one of the posts passes, the rear portions of the two levers being tied together by a springy clip which urges the levers into locking engagement with the respective post, thereby preventing movement of the backrest along the two posts.

6. A hospital bed backrest according to claim 5, in which the hollow casing contains a sliding bolt or shaft with a rounded front end which is urged by a spring into a position where the rounded end is clear of the adjacent rear ends of the two levers, and in which a button projecting from the casing can be depressed to move a cam or other member in the casing into a position where it displaces the sliding boltorshaftin a longitudinal direction so as to force the end portions of the levers apartagainstthe action of the springy clip, thereby bringing the two levers into a position where their locking grip on the respective post is released to permit the backrest to move along the two posts.

7. A hospital bed backrest according to claim 6, in which a spring acts on the cam or other member so as to restore the latterto its original position of rest when the button is released, thereby allowing the sliding bolt or shaftto return to its original position where its nose is clear of the levers so that the latter can return to their locking position under the action of the springy clip.

8. A hospital bed backrest substantially as described herein with reference to the accompanying drawings.