GB2305851A - Improvements relating to backrests - Google Patents

Abstract

A backrest attachment for home nursing with an ordinary domestic bed comprises first and second frames hinged together and an electric battery powered actuator for lifting the one frame relative to the other. Figure 3 shows the parts in a backrest elevated position. In the flat position the frames are sandwiched between the mattress and the bed base whilst the actuator and cranks lie at the side of the base. The actuator comprises an electric motor 38 driving an axially movable shaft 36 which is linked to the movable part of the back rest by crank 30. The shaft is driven by a recirculating ball arrangement.

Description

IMPROVEMENTS RELATING TO BACKRESTS This invention relates to a backrest for a bed.

It is well known to provide for example hospital beds with backrests. In the simplest form, the head end of the bed has a frame hinged along its top edge so that it can hang in a vertical and ineffective position when the bed is in ordinary use. Alternatively it can be swung outwardly so that the lower end of the frame advances along the length of the bed to enable pillows to be piled to support an occupant sitting up in bed.

In more sophisticated arrangements, the mattress frame itself comprises a pair of parts hinged about a common axis, or mechanism for the same effect, so that a portion of the length of the mattress frame towards the head end of the bed can be lifted upwardly using the actual mattress instead of pillows as the back support.

The mattress also may be made of separate cushions or cushion parts hinged together to facilitate this action.

Usually, a hospital bed with this facility is also provided with a number of other facilities. For example it may be height adjustable, tiltable, provided with sockets for drip poles and so on.

Where a person is to be nursed at home it is often necessary or at least desirable to use an existing bed.

The object of the present invention is to provide a backrest facility for use with an ordinary bed in such situations.

According to the invention considered broadly, a backrest attachment for a bed comprises a part for location on the bed, a backrest proper hinged to the said part and movable between a pair of positions in one of which the backrest and part are effectively co-planar and so that both may lie between the mattress and a mattress base allowing the mattress to be in substantially its flat condition, and in the other of the positions raising one portion of the mattress; and means for causing the hinging movement.

Preferably the means for causing the hinging movement is an electric motor. Preferably the motor drives a shaft to a variable degree of projection, and the shaft may be coupled to the backrest proper by means of a crank pivoted on the hinge axis.

According to an important feature of the invention the motor and any associated equipment is located laterally of said part so as to lie at one side of the bed and not interfere with the normal flat condition of the mattress.

Further features of the invention will be apparent from the accompanying description of a presently preferred embodiment, in conjunction with the accompanying drawings in which: Figure 1 is a fragmentary plan view; Figure 2 is a fragmentary side view showing the parts in one position, and Figure 3 is a view similar to Figure 2 showing the parts in another position.

A conventional domestic bed comprises a divan base 10 and a mattress 12 which rests on that base.

The backrest of the invention comprises a first U shaped frame having parallel side limbs 14 14 connected by a transverse member 16. A second part of the backrest comprises a second U shaped frame having parallel side members 18 18 connected by a transverse portion 20. The side members 18 are fast with a cross piece 22 and the cross piece and transverse member 20 are connected by a series of parallel members 24. Alternatively the backrest proper (18,20,22) may comprise a panel.

The cross member 20 is hinged on its axis via a knuckle part 26 fixed to one of the side members 14. A shaft journalled in the knuckle and the cross piece 22 carries crank arm 28 which extends radially from the said hinge axis through a gap between the knuckle and cross member 22, and a second crank arm 30 extends in like fashion but at an angle to the crank arm 28 at the opposite end of the knuckle 26.

Crank arm 28 carries an abutment pad 32 which underlies one side member 18 of the backrest, whereas crank arm 30 is connected at point 34 to an output shaft 36 extending from an actuator pack 38. The actuator pack is supported by a lug 40 carried by the side member 14.

Figure 1 shows the backrest of the invention in position on the divan base, with the mattress removed for clarity. It will be seen that one side member 14 and the cross member 16 lie on the divan base but the second side member 14 is located close to a lateral edge of the divan base so that the actuator pack 38 can extend at the side of the base but not above the base. When the mattress is in position as shown in Figure 2 the two parts 14-24 are effectively sandwiched between the base and the mattress and occupy very little space so that the mattress may be substantially flat, but the actuator pack is not so sandwiched.

The actuator pack may comprise an electric motor driving a recirculating ball nut mounted on the shaft 36 with an associated power pack for example a rechargeable electric battery. There may be a control unit for the actuator in the form of a hand-held control at the end of a wander lead connected to the actuator. When appropriately switched the motor rotates in one or other direction according to the switching, and the effect is to axially displace the shaft 36 in the direction of the arrows A-A Figure 2 one way or the other according to the direction of switching. This may swing the crank arms 28, 30 clockwise from the Figure 2 position to the Figure 3 position. The angular movement possible will depend upon the geometry and the length of the shaft 36.

Typically a movement from flat to a 60 degree inclination of the mattress and backrest will be provided.

It will be appreciated that the movement of the pin 34 will be arcuate, but this can be accommodated by swinging of the complete actuator pack about a pivot point 42 on the lug 40.

The use of the abutment 28 coupling the motor to the backrest allows for example the mattress and hinged parts 18-24 to be lifted by hand independently of the motor: conversely, if the motor is being used to lower the parts and there is any obstruction in the form of a person's hand or any objects placed below the lifted frame then the motor may continue to run but without pulling the frame and mattress onto the obstruction and thus possibly avoiding injury or damage.

The electrical circuitry of the actuator may incorporate current limiting devices to prevent overload.

Figure 1 also illustrates an abutment 44 on the first part 16 which acts as a stop for the second part preventing movement from the Figure 3 position beyond the Figure 2 position.

The outer frame 14 16 may be provided with additional brackets to contact edges of the divan base to maintain the backrest in position relative to the bed as a whole: and/or fixing straps may be provided to encircle the base and first frame on the one hand and possibly the mattress and second frame on the other hand to maintain all of the parts in the required positions.

A shield or guard may be provided to cover the moving parts of the mechanism for safety and/or aesthetic reasons, but is omitted from the drawings for clarity.

Instead of using a battery, the motor may be mains powered. Alternatively, and in a presently preferred embodiment the power pack is a back-up or stand-by battery for use in the event of mains failure.

Claims (4)

1. A backrest attachment for a bed comprises a part for location on the bed base, a backrest proper hinged to the first part and movable between a pair of positions in one of which the two parts are effectively co-planar and so that the backrest may lie between a mattress and a mattress support base allowing the mattress to be in substantially its flat condition, and in the other of the positions raising one portion of the mattress; and means for causing the hinging movement.

2. A backrest as claimed in Claim 1 wherein the means for causing the hinging comprise an electric motor.

3. A backrest as claimed in Claim 2 wherein the electric motor includes a recirculating ball nut arranged to drive a shaft axially in one or other direction according to the direction of the motor and displacing a crank to lift or lower the backrest.

4. A backrest as claimed in Claim 3 wherein the actuator is pivotally mounted laterally of the backrest to lie at the side of the mattress, and in a manner permitting swinging of the actuator during the lifting and lowering movement.