Abstract: A circuit for measuring body impedance comprising a voltage source having a predetermined frequency and a current source; a first pair of electrodes adapted to receive one portion of the body for applying said current source to said body; a second pair of electrodes adapted to receive another portion of the body for sensing a voltage therebetween; a comparator having first and second inputs and an output for producing an output signal based on signals applied to said first and second inputs; an instrumentation amplifier arrangement coupled to one of said comparator inputs and responsive to the voltage across the second pair of electrodes for providing an input signal to said first comparator input; a variable resistor coupled to the second input of said comparator and responsive to said voltage source for developing a first voltage signal applied to said second comparator input; and a processor responsive to the output signal of the comparator for controlling the resistance of the variable resistor to cause a

Abstract: A load cell for an electronic scale, which is capable of providing both load support and load measurement in a planar member. This is accomplished by configuring the load cell as a substantially flat circular plate having an E-shaped deflectable member defined therein. The E-shaped member includes three beams, at least one of which includes a sensor arrangement that responds to a load applied to the deflectable member by generating an electrical signal that is indicative of the load applied to the E-shaped member.

Abstract: An electrical weighing scale for measuring the weight of a user having has a substantially transparent platform, a plurality of supports, and a display assembly. Piezoresistive sensors, disposed in the supports, change resistance in response to a change in the weight applied to the scale. The piezoresistive sensors include piezoresistive elements arranged in a half bridge structure that has been calibrated to provide zero balance, span matching and impedance normalization. The sensors are coupled in parallel to a display. The parallel arrangements produces a composite output signal that enables any number of sensors to be used in the scales design.

Abstract: The present weight scale performs automated self calibration by periodically initiating a measurement operation to determine the zero offset from a true weight reading due the weight scale's intrinsic weight. The weight scale's intrinsic weight will vary due to changes in environmental conditions such as temperature and humidity, which impact the behavior of the internal electronics that perform the weight measurement operations. The automated self calibration is provided by a counter circuit, clocked by a low power oscillator, that periodically initiates the weight scale's electronics to undertake a weight measurement of the tare weight value of the scale. The tare weight value is stored in memory until replaced by a subsequent tare weight value calculation. During a weight measurement operation the gross weight measurement is deducted by the tare weight value stored in memory to arrive at a net weight representing a user's true weight.

Abstract: Apparatus and methods for noninvasively measuring cardiovascular system parameters. According to a first preferred embodiment, the apparatus generates a time varying electrical voltage waveform having voltages corresponding to systolic and diastolic arterial pressures of the subject, the parameters being modelled by a lumped element electric circuit model analogous to the living subject's cardiovascular system, said circuit model including a systolic capacitor analogous to arterial compliance during systole, said apparatus comprising means for computing the value of said systolic capacitor from a measurement of an elapsed time between two voltage levels within a portion of said voltage waveform corresponding to systole, according to a predetermined criteria; and means for computing at least one said cardiovascular system parameter from said capacitor value. According to a second embodiment, a time-varying systolic arterial compliance is measured by measuring an arterial pulse pressure waveform.

Abstract: Apparatus and methods for noninvasively measuring cardiovascular system parameters. According to a first preferred embodiment, the apparatus generates a time varying electrical voltage waveform having voltages corresponding to systolic and diastolic arterial pressures of the subject, the parameters being modelled by a lumped element electric circuit model analogous to the living subject's cardiovascular system, said circuit model including a systolic capacitor analogous to arterial compliance during systole, said apparatus comprising means for computing the value of said systolic capacitor from a measurement of an elapsed time between two voltage levels within a portion of said voltage waveform corresponding to systole, according to a predetermined criteria; and means for computing at least one said cardiovascular system parameter from said capacitor value. According to a second embodiment, a time-varying systolic arterial compliance is measured by measuring an arterial pulse pressure waveform.

Abstract: An indoor/outdoor thermometer system employs a wireless infrared telemetry link. An outdoor unit capable of being mounted on or in proximity to a window is equipped with a processor and modulation means to enable measurement of outdoor temperature and conversion to modulated data pulses. The data pulses are coded to provide noise immunity. The data is transmitted in a free space infrared medium and detected by an indoor unit which displays the outdoor temperature. The indoor unit is mounted in a suitable convenient indoor location. Indoor temperature may also be measured and displayed. An internal timing data transmission feature is employed to drastically reduce power consumption, enabling long lasting lithium type batteries to be deployed as the power source.

Abstract: An acoustic ranging apparatus directs a burst of acoustic energy toward an acoustically reflective target object. The time it takes for an echo to return to the ranging apparatus is measured to determine the distance between the ranging apparatus and the object. The echo is received, amplified, and compared with a threshold voltage which decays in time in a manner which simulates the attenuation of acoustic energy as a function of distance travelled in the medium. The attenuation function is substantially simulated over the distance range that the ranging apparatus is intended to accurately measure by means of a simple, low cost first order linear circuit. The ranging apparatus responds only to echoes having a magnitude which exceeds the threshold voltage. Suprious or false echoes, such as those due to reflection of acoustic energy in the side lobes produced by an acoustic energy transducer in the ranging apparatus, are ignored.