LIQUID CONCENTRATION MEASURING DEVICE
First Claim
1. A liquid concentration measuring device comprising:
- a detection electrode pair including a pair of electrodes facing each other;
a switching section connected to switch charging and discharging of the detection electrode pair;
an operation signal outputting section configured to produce operation signals of a predetermined frequency to control switching operation of the switching section at a predetermined period; and
a measured value outputting section configured to produce a voltage for charging the detection electrode pair through the switching section and to produce a detection voltage corresponding to a static electric capacity of the detection electrode pair as a measured value,wherein the operation signal outputting section is configured to produce a first operation signal of a first frequency and a second operation signal of a second frequency different from the first frequency for operating the switching section at a first period and a second period, respectively, andwherein the measured value outputting section is configured to produce a first detection voltage and a second detection voltage when the switching section is operated at the first frequency in the first period and the second frequency in the second period, respectively.
1 Assignment
0 Petitions
Accused Products
Abstract
A liquid concentration measuring device has first and second switches, which are turned on and off at two frequencies. When the first switch is turned on and the second switch is turned off, a detection electrode pair is charged. When the first switch is turned off and the second switch is turned on, the positive side of the detection electrode pair is grounded so that the charged detection electrode pair discharges. The difference between the output voltages of an amplifier produced by charging and discharging the detection electrode pair at the two frequencies is used to determine an alcohol concentration in gasoline.
62 Citations
18 Claims
-
1. A liquid concentration measuring device comprising:
-
a detection electrode pair including a pair of electrodes facing each other; a switching section connected to switch charging and discharging of the detection electrode pair; an operation signal outputting section configured to produce operation signals of a predetermined frequency to control switching operation of the switching section at a predetermined period; and a measured value outputting section configured to produce a voltage for charging the detection electrode pair through the switching section and to produce a detection voltage corresponding to a static electric capacity of the detection electrode pair as a measured value, wherein the operation signal outputting section is configured to produce a first operation signal of a first frequency and a second operation signal of a second frequency different from the first frequency for operating the switching section at a first period and a second period, respectively, and wherein the measured value outputting section is configured to produce a first detection voltage and a second detection voltage when the switching section is operated at the first frequency in the first period and the second frequency in the second period, respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
-
Specification