System For Measuring And Indicating Changes In The Resistance Of A Living Body
First Claim
1. A device for indicating changes in resistance of a living body comprising:
- a resistance measuring circuit having external leads for sensing the resistance of a living body placed across the external leads;
amplifier means for producing an analog measurement signal indicative of the sensed body resistance;
an indicator circuit for displaying visually perceivable indicia representative of the sensed body resistance;
a digital processing unit for digitizing and digitally processing the measurement signal to substantially offset the effects of component aging, tolerances and temperature on the accuracy of the measurement signal; and
indicator means responsive to the processed measurement signal for displaying visually perceivable indicia representative of small sensed body resistance changes.
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Abstract
An improved device for indicating and measuring small variations in the resistance of a living body is disclosed which utilizes a central processing unit to digitally process sensed body resistances and drive a resistance-indicating display while compensating for the effects of component aging, component tolerances and component temperatures. The device includes an automatic calibration circuit that is automatically activated on each powering up of the device to measure and store measurement values for a plurality of synthesized body resistances that are used to form a compensation model against which sensed body resistances are, subsequently compared for automatic adjustment of display driving measurement values. The central processing unit additionally adjusts the gain of the meter-driving signal by a gain factor dependant on a user-selected meter-sensitivity setting to avoid previously experienced difficulties in monitoring small changes in body resistance caused by difficulty in setting the initially desired meter reading at certain meter-range values, as well as occasional false and unexpected reversals of meter reading as the meter'"'"'s range was adjusted.
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Citations
10 Claims
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1. A device for indicating changes in resistance of a living body comprising:
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a resistance measuring circuit having external leads for sensing the resistance of a living body placed across the external leads; amplifier means for producing an analog measurement signal indicative of the sensed body resistance; an indicator circuit for displaying visually perceivable indicia representative of the sensed body resistance; a digital processing unit for digitizing and digitally processing the measurement signal to substantially offset the effects of component aging, tolerances and temperature on the accuracy of the measurement signal; and indicator means responsive to the processed measurement signal for displaying visually perceivable indicia representative of small sensed body resistance changes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification