Electronic tire gauge
First Claim
1. A digital tire gauge for measuring the pressure in a tire, said digital tire gauge having electronic circuitry for generating a signal indicative of the measured pressure, a digital display for displaying the signal indicative of the measured pressure and a power source for powering said electronic circuitry and said digital display, said digital tire gauge comprising:
- valve stem fitting means for receiving the valve stem of a tire;
pressure transducer means coupled to said valve stem fitting means for generating a pressure signal representing pressure sensed by said pressure transducer means;
oscillator means for generating an oscillating signal comprising a periodic sequence of cycles;
comparator means responsive to said pressure signal and said oscillating signal for generating comparison signals resulting from the comparison of said oscillating signal to said pressure signal, said comparison signals comprising first portions and second portions, each of said first portions having a time duration equal to the time the pressure signal is greater than the oscillating signal and each of said second portions having a time duration equal to the time the pressure signal is less than the oscillating signal;
controller means disposed to measure the time durations of said first portions of said comparison signals for generating display signals indicative of pressure sensed by said transducer means for display on the digital display, said controller means generating said display signal after a plurality of cycles of said oscillating signal have been compared to said pressure signal by said comparator means.
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Accused Products
Abstract
An electronic tire pressure gauge has a tire valve stem receiver, a thin silicon square diaphragm with four diffused resistors configured in a full Wheatstone bridge as a pressure transducer, a voltage controlled oscillator, a comparator, a clock, a microprocessor with program memory, and a display. The comparator compares the stable transducer output for a given pressure with the voltage-controlled oscillator output, to yield a comparator pulse which goes high while the transducer signal is greater than the oscillator signal. The clock provides bus cycles used by the microprocessor for counting the duration of the high comparator pulse. Multiple high comparator pulses are compared, and the longest duration is selected and converted to a pressure value and displayed. Battery power is conserved by a power on/off algorithm.
46 Citations
17 Claims
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1. A digital tire gauge for measuring the pressure in a tire, said digital tire gauge having electronic circuitry for generating a signal indicative of the measured pressure, a digital display for displaying the signal indicative of the measured pressure and a power source for powering said electronic circuitry and said digital display, said digital tire gauge comprising:
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valve stem fitting means for receiving the valve stem of a tire; pressure transducer means coupled to said valve stem fitting means for generating a pressure signal representing pressure sensed by said pressure transducer means; oscillator means for generating an oscillating signal comprising a periodic sequence of cycles; comparator means responsive to said pressure signal and said oscillating signal for generating comparison signals resulting from the comparison of said oscillating signal to said pressure signal, said comparison signals comprising first portions and second portions, each of said first portions having a time duration equal to the time the pressure signal is greater than the oscillating signal and each of said second portions having a time duration equal to the time the pressure signal is less than the oscillating signal; controller means disposed to measure the time durations of said first portions of said comparison signals for generating display signals indicative of pressure sensed by said transducer means for display on the digital display, said controller means generating said display signal after a plurality of cycles of said oscillating signal have been compared to said pressure signal by said comparator means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A gauge for measuring a physical stimulus and displaying the measured physical stimulus in human readable form, said gauge comprising:
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a transducer for sensing the physical stimulus and for providing a transducer signal representing the sensed physical stimulus; oscillator means for generating an oscillating signal comprising a periodic sequence of cycles; comparator means for generating comparison signals, said comparison signals resulting from the comparison of the oscillating signal to the transducer signal, said comparator means coupled to said transducer and said oscillator means, said comparison signals comprising first portions and second portions, each of said first portions having a time duration equal to the time the transducer signal is greater than the oscillating signal and each of said second portions having a time duration equal to the time the transducer signal is less than the oscillating signal; microcontroller means disposed to measure the time durations of said portions of said comparison signals for generating display signals indicative of the physical stimulus sensed by said transducer means for display in human readable form, said microcontroller means comprising program memory means for storing a program for controlling said microcontroller to process said comparison signals and generate said display signals. - View Dependent Claims (15, 16, 17)
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Specification