Surgery – Truss – Pad
Patent
1993-01-06
1995-05-30
Kamm, William E.
Surgery
Truss
Pad
128903, A61B 504
Patent
active
054193362
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to monitoring heart beat or pulse rate.
2. The Prior Art
Conventionally, such monitoring is done using electro-magnetic RF techniques, typically using a harness and with signal transmission through at least one layer of clothing, often a T-shirt. Use of radio frequency, typically about 800 KHz, can give most undesirable interference effects.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an alternative system free of such possible interference effects; specifically do so utilising infra-red transmission and reception.
Such transmitter/reception systems are, of course, well known from remote controls for domestic and other electronic equipment, such as televisions and audio systems or motor vehicle locking/alarm systems. However, in all such cases, the infra-red source or transmitter is invariably exposed and it has been established that application of such existing infra-red transmission/reception technology to heart beat monitoring is incapable reliably of penetrating a layer of clothing.
Accordingly, it is a particular object of this invention to produce an infra-red communication system that is free of such problems, i.e. affectively provides compatibility of utility with existing RF systems, including capability for a reasonable operating life of practical batteries for the transmitter.
According to the invention there is provided an infra-red transmitter comprising transducer means for sensing heart beat and producing a detectable electrical signal, infra red transmission means energisable from a battery, and signal processing means responsive to transducer output signals representative of heart beats, for producing therefrom short pulses that serve to gate electrical energy originating with said battery to the infra-red transmission means at voltage and duration that secure detectable penetration of a layer of clothing along with acceptably low battery power consumption.
Embodiments of this invention are capable of implementation using conventional heart beat sensing transducer means, and conventional infra-red receiver means namely photodiodes or the like; and the latter will usually be coupled through an amplifier/receiver producing signals for a microprocessor feeding suitable recording and/or display means.
Moreover, successful operation has been achieved using conventional light emitting diodes (LEDs) as the infra-red transmission means, and 3-volt lithism batteries.
In order to achieve sufficient intensity of infra-red transmission, energisation of LEDs have been at order of magnitude greater than that normal for exposed LED remote controller systems, actually as high as 1.5 amp or more through each of a parallel bank or set of LEDs.
However, in order to sustain useful battery life, gate pulse widths controlling such LED energisation have been set below 100 micro-seconds, actually about 50 micro-seconds. That, of course compares with LED energisation currents of milliamps or tens of milliamps for energisation of otherwise exposed remote controller systems, i.e. as much as two or three orders of magnitude higher energisation, and with touch-operated energisation intervals of up to seconds, i.e. as little as two or three orders of magnitude less energisation time, and thus an entirely different approach to infra-red communication systems.
It is not, of course, to be taken that pulse widths longer than 100 micro-seconds are wholly impractical for battery-powered devices. The type of battery concerned can be taken into account, including as to whether it is re-chargeable, all within the bounds of tolerance of battery size and/or frequency of required re-charging. However, it is not envisaged that pulse-widths longer than a few milliseconds, perhaps up to 5, could be tolerable in practice, though an order of magnitude less would improve tolerable practicality. The advantages of reducing pulse widths within practical and economic considerations should be appreciated, particularly as specifically to b
REFERENCES:
patent: 3910257 (1973-10-01), Fletcher et al.
patent: 4151407 (1979-04-01), McBride et al.
patent: 4677982 (1987-07-01), Llinas et al.
patent: 4987902 (1991-01-01), Couche
patent: 5038782 (1991-08-01), Gevins et al.
patent: 5307817 (1994-05-01), Guggenbuhl et al.
Weller "Modulation Scheme Suitable for Infra-Red Biotelemetry" Electronics Letters, vol. 21, No. 14, 4 Jul. 1985 pp. 601-602.
Arker Marianne
Kamm William E.
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