EP0581474B1

EP0581474B1 - Beds

Info

Publication number: EP0581474B1
Application number: EP93305441A
Authority: EP
Inventors: Stephen Hayes
Original assignee: Huntleigh Technology Ltd
Current assignee: Huntleigh Technology Ltd
Priority date: 1992-07-25
Filing date: 1993-07-12
Publication date: 1997-04-02
Anticipated expiration: 2013-07-12
Also published as: ATE150959T1; DK0581474T3; GB9314362D0; GB2269916B; GB2269916A; GB9215852D0; DE69309360T2; EP0581474A1; DE69309360D1

Abstract

A hospital bed has one or more electric actuators (motors) for raising and lowering the bed, raising and lowering the backrest and the like. Two control sets are provided, one for occupant's use and the other for medical staff use. The electrical equipment is duty cycled rated so as for example to be run for a maximum of 6 minutes continuously and then become inoperable for example for one hour to avoid damage. After the full 6 minutes use, capability of usage may be restored with increments such as 30 second capability after each 5 minutes of non-use. The medical staff control set is arranged to allow a longer period of continuous usage, or aggregated usage than the occupant's control set so as to allow adjustment for emergency procedures.

Description

This invention relates to hospital beds of the kind described in EP-A- 04 88 552 and GB 2 250 189-A for example. Such beds comprise a plurality of electric actuators, motors or the like connected to a control mechanism so that the bed may be raised and lowered and possibly also tilted either longitudinally or from side to side or both, and/or profiled so as to have an upwardly inclined backrest and possibly also a knee break. The motors may be controlled by a hand control unit having switches or push-buttons.
Many different beds of the kind are known. They may be made using continuously rated electric motors and the like, that is ones capable of running continuously. This will be expensive, and is also considered unnecessary in practice, since only occasional usage is required to adjust the position of the bed parts.
It is therefore usual to employ smaller motors which can be supplied from small transformers (hospital equipment is usually low voltage and DC so that battery back-up is possible) having a specific duty cycle, that is to say intended to run for a maximum of perhaps five or six minutes per hour. This still allows the bed to be adjusted through any normal cycle. Such smaller transformers and motors are substantially cheaper.
However, if the duty cycle is exceeded, as may occur if a visitor to the hospital plays with the controls, over-use which might lead to overheating and damage is prevented by a cut-out of some kind. In the prior art this has been a thermal cut-out which automatically resets when temperature falls to a predetermined level. After cut-out the bed is unusable until the switch is reset. This creates a risk of inconvenience for example if cut-out occurs when the bed is in a position unsuitable for some reason, for example at an undesired tilt angle, but it is even more serious in that cut-out prevents adjustment of the bed which may be needed for urgent medical procedures.
The object of the invention is to solve this problem, avoid the use of continuously rated motors and the like, but avoid the risks referred to.
According to the invention a hospital bed comprises at least one electric motor or the like for adjusting the position of one part of the bed relative to another, said motor having a duty cycle, and a (first) control set for the bed connected in a circuit including cut-out means which are automatically operable and automatically re-set, and is characterised in that the automatic operation occurs after a first predetermined period of continuous usage and the re-setting occurs after a period of non-use, and by the provision of a second control set for the bed connected in a circuit including cut-out means automatically operable after a second predetermined period of continuous usage which is longer than said first predetermined period of continuous usage and likewise is automatically resettable after a period of non-use.
Hence, the first set may be for use by the patient, and the second set for use by medical staff. If the patient exceeds the available time from that handset, the extra time available from the medical staff handset allows an unsuitable position of the bed to be changed, and also allows for operation for emergency procedures.
In a presently preferred embodiment of the bed, motors are provided to raise and lower the mattress frame. Typically the mattress is required to be in a high position for ordinary nursing procedures, so as to avoid stooping on the part of the medical staff, and in a low position to enable the patient to get in and out of bed easily.
Additionally the mattress may be tiltable so as to have the feet lower than the head or vice versa. For some medical procedures lateral tilt is required.
Some patients prefer or need to sit up in bed and an inclinable backrest is provided driven possibly by a separate motor, and this may be assisted by a so-called knee break in which a portion of the mattress is profiled to extend upwardly under the thighs to the patient's knees and then downwardly to the feet. This may require yet another motor.
All of these adjustments, according to the invention, are effected by electric actuators or motors which have a specific duty cycle and are not designed for continuous running.
In the invention, two handsets are provided for controlling the motors. They may be identical in the sense of each being capable of controlling any or all of the motors, but it is preferred to provide the patient's handset with a more limited facility perhaps amounting to control of raise and lower and profiling only. Alternatively or additionally the nursing staff handset may have control switches which effectively enable or disable the patient's set controls one by one, as well as providing for control of the movements from the nursing staff set. The enabling and disabling facility may be used so that for example when a patient is in intensive care, or is newly emerged from the operating theatre, the patient's set may be totally disabled, and as recovery takes place the patient may be given control over perhaps profiling initially, and then mattress raising and lowering, and so on.
There are two possibilities for the arrangement of the time control system. In one arrangement, the nursing staff handset allows continuous operation for a time equal to the rated duty cycle of the motors and other equipment, with an alarm or warning lamp lit when a predetermined portion of such time is used up. For example with 7.5 minutes rating, the nursing set warning may be activated after 6 minutes has been used. In this case the patient set may allow usage for only the same 6 minutes and possibly with a warning after a shorter period, for example 5 minutes.
In the alternative, the patient's control set is capable of usage for the full normal rated duty cycle for example the 6 minute period, again with a warning: and the nurse's set allows override for an additional one of the half minutes, for emergency purposes, again with some kind of alarm to show that there is little reserve.
When the motors run continuously for a shorter time, for example two minutes, it will be clear that 4 or 5 1/2 minutes (in the mentioned example) remain. If a further usage period starts before any additional availability is restored by the passage of time, the additional usage is effectively added to the first period of use. Thus, after the first 2 minutes, and a further 4 minutes, the patient's control would become unusable.
Restoration is effected according to the motor rating. If a one hour period of non-use is needful after the full usage capability, then preferably this is apportioned so that each continuous 5 minutes of non usage adds half a minute to the usage capability. Thus with non-use for more than one hour and then 2 minutes' use, 4 minutes is immediately available until there has been a period of 5 minutes of non-use, when 4 1/2 minutes become available, and so on. After the full 6 minutes (or 7 1/2 in the case of the nursing staff set) a 5 minute period of non-usage restores a 1/2 minute availability for use.
Each motor may be individually monitored, so that for example excess usage of one motor may disable it, without affecting the other motors which remain enabled.
Preferably the timers and cut-out switches are connected in circuits with a memory and a controlling microprocessor.

Claims

A hospital bed comprising at least one electric motor or the like for adjusting the position of one part of the bed relative to another, said motor having a duty cycle, a (first) control set for the bed connected in a circuit including cut-out means which are automatically operable and automatically re-set, and characterised in that the automatic operation occurs after a first predetermined period of continuous usage and the re-setting occurs after a period of non-use, and also by the provision of a second control set for the bed connected in a circuit including cut-out means automatically operable after a second predetermined period of continuous usage which is longer than said first predetermined period of continuous usage and likewise is automatically resettable after a period of non-use.
A bed as claimed in Claim 1 wherein said first and second sets are both operable to control certain adjustments of the bed and second set is also operable to control further adjustments of the bed.
A bed as claimed in Claim 1 or Claim 2 arranged so that each unit of a lapsed time of non-use increases the available usage time by a specific amount up to the maximum of the duty cycle.
A bed as claimed in any preceding Claim wherein operation of the cut-out means by the first control set provides a visible and/or audible indication on both control sets.