Apparatus for detecting alcohol content of liquid
First Claim
1. An apparatus for detecting an alcohol content of a liquid, comprising:
- dielectric constant detecting means including a resonance circuit whose resonance frequency changes in accordance with dielectric constant of a liquid containing alcohol;
resonance frequency detecting means for outputting a frequency signal having a same frequency as the resonance frequency of said resonance circuit of said dielectric constant detecting means;
frequency divider means for dividing the output frequency of said resonance frequency detecting means to thereby output a signal indicative of said dielectric constant on the basis of which said alcohol content can be determined; and
frequency division ratio adjusting means for adjusting a frequency division ratio of said frequency divider means.
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Accused Products
Abstract
An apparatus for detecting an alcohol content of a liquid with high accuracy regardless of variance in a resonance frequency of a parallel resonance circuit constituted by inductance of a coil, capacity presented by a fluid within a liquid passage of a sensor unit and others. High-frequency voltage signals appearing at both ends of a resistor of a detector circuit connected in series to the coil are compared in respect to phase by a phase comparator, wherein difference signal resulting from the comparison is supplied to a voltage-controlled oscillator through a comparison integrator, the oscillation signal Svco of the oscillator being supplied to one end of the resistor through an amplifier. Through this phase synchronization loop, the oscillation frequency of the oscillator is forced to coincide with the resonance frequency, whereby a signal Sout having a frequency bearing one-to-one correspondence to the resonance frequency is obtained from a frequency divider. By providing a frequency division ratio adjusting circuit for adjusting a frequency division ratio of the frequency divider, alcohol content can be detected with high frequency regardless of apparatus-dependent variance in the resonance frequency.
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Citations
4 Claims
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1. An apparatus for detecting an alcohol content of a liquid, comprising:
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dielectric constant detecting means including a resonance circuit whose resonance frequency changes in accordance with dielectric constant of a liquid containing alcohol; resonance frequency detecting means for outputting a frequency signal having a same frequency as the resonance frequency of said resonance circuit of said dielectric constant detecting means; frequency divider means for dividing the output frequency of said resonance frequency detecting means to thereby output a signal indicative of said dielectric constant on the basis of which said alcohol content can be determined; and frequency division ratio adjusting means for adjusting a frequency division ratio of said frequency divider means. - View Dependent Claims (2, 3, 4)
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Specification