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Voltage Discriminator: A Method and Circuit for Detecting Voltage Changes

IP.com Disclosure Number: IPCOM000107400D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 7 page(s) / 275K

Publishing Venue

IBM

Related People

Thorne, RE: AUTHOR

Abstract

Disclosed is an electronic method by which a "sliding" window comparator may be created such that numerous and/or progressive voltage changes may be detected. The method described utilizes only one subtracter allowing for a very low parts count.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 23% of the total text.

Voltage Discriminator: A Method and Circuit for Detecting Voltage Changes

       Disclosed is an electronic method by which a "sliding"
window comparator may be created such that numerous and/or
progressive voltage changes may be detected.  The method described
utilizes only one subtracter allowing for a very low parts count.

      An example of the utility of this invention might be a system
that detects any and all voltage changes of 0.1 volt without regard
to any particular reference voltage.  Through the use of suitable
sensors or transducers, the method could be used to monitor
temperature, pressure, velocity, intensity or other parameters,
properties or phenomena.

      An example is given of circuitry that might be used to detect
temperature changes of 0.1~C along a useful range of 0~C-50~C.  By
suitable choice of components, the range and sensitivity could be
changed to suit other needs.

      Traditionally, detection of voltage change is achieved through
the use of a "window comparator".  This method utilizes two reference
voltages to define a "window". Voltage comparators are used to
compare some input signal to these reference voltages and determine
if the input signal is "outside" of the window that they define.
Typically, the reference voltages are fixed at some preselected value
and so the window is "fixed".

      The window comparator method is useful in applications such as
thermostats where one desires to know if the temperature is outside
of the preselected range.

      The disclosed Voltage Discriminator method could be used to
monitor phenomenon that are continuously varying over a range much
larger than the window.  Each time the input is determined to be
outside the limits of the window, this fact is indicated and the
window "slides" such that it is centered around the current input
value.

      A Biofeedback Monitor is an example of a practical device that
could utilize the Voltage Discriminator method disclosed.  A
temperature sensor could be used to detect surface skin temperature
fluctuations, such as those that may be exhibited by an individual
while experiencing stress and/or relaxation.

      A second example might be a device to monitor the ambient
temperature outside of an aircraft.  The device would give an
indication of the temperature fluctuations such as those that exist
in the atmosphere in conjunction with thermals (rising columns of
warm air).  The device might be used to aid sailplane pilots in
locating thermals.

      Both of the above devices could be built using the circuitry
shown later in the example of Fig. 3 with little or no modification.

      Fig. 1 shows a block diagram of a system which might utilize
the method disclosed.  The system utilizes a transducer that produces
a voltage that varies with the property of interest.  The scaling
circuitry transforms the input voltage over the range of interest to
a voltage appropriate for the V...