Small current detector circuit and locator device using the same
First Claim
1. A small current detector circuit comprising:
- a first and a second capacitor;
a pulse drive circuit which drives one terminal of each capacitor by a pulse signal and charges and discharges said capacitors in synchronism with the rise and fall of the applied pulse so as to generate a first and a second detection signal at the other terminal of each capacitor;
a connection circuit having a first and a second input terminal for receiving said first and second detection signals, respectively, and a first and a second output terminal, said connection circuit connecting said first and second input terminals to said first and second output terminals, respectively, in synchronism with the rise of said pulse signal whereas said first input terminal is connected to said second output terminal and said second input terminal to said first output terminal in synchronism with the fall of said pulse signal;
a current generator circuit which receives said first and second detection signals from said first and second output terminals, respectively, to generate a current representing the difference between the levels of said signals; and
an integrator circuit for integrating the output current from said current generator circuit, at least one of said first capacitor and said second capacitor being provided in detection portion of the detector circuit.
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Accused Products
Abstract
The improved small current detector circuit and locator device each include a first and a second capacitor, a pulse drive circuit which drives one terminal of each capacitor by a pulse signal and charges and discharges the capacitors in synchronism with the rise and fall of the applied pulse so as to generate a first and a second detection signal at the other terminal of each capacitor. A current generator circuit receives the first and second detection signals and generates a current representing the difference between the levels of said signals. An integrator circuit integrates the output current from the current generator circuit. At least one of the first capacitor or second capacitor is provided in a detection portion of the detector circuit or locator device.
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Citations
12 Claims
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1. A small current detector circuit comprising:
- a first and a second capacitor;
a pulse drive circuit which drives one terminal of each capacitor by a pulse signal and charges and discharges said capacitors in synchronism with the rise and fall of the applied pulse so as to generate a first and a second detection signal at the other terminal of each capacitor;
a connection circuit having a first and a second input terminal for receiving said first and second detection signals, respectively, and a first and a second output terminal, said connection circuit connecting said first and second input terminals to said first and second output terminals, respectively, in synchronism with the rise of said pulse signal whereas said first input terminal is connected to said second output terminal and said second input terminal to said first output terminal in synchronism with the fall of said pulse signal;
a current generator circuit which receives said first and second detection signals from said first and second output terminals, respectively, to generate a current representing the difference between the levels of said signals; and
an integrator circuit for integrating the output current from said current generator circuit, at least one of said first capacitor and said second capacitor being provided in detection portion of the detector circuit. - View Dependent Claims (2, 3)
- a first and a second capacitor;
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4. A locator device comprising:
- a first and a second capacitor;
a pulse drive circuit which drives one terminal of each capacitor by a pulse signal and charges and discharges said capacitors in synchronism with the rise and fall of the applied pulse so as to generate a first and a second detection signal at the other terminal of each capacitor;
a connection circuit having a first and a second input terminal for receiving said first and second detection signals, respectively, and a first and a second output terminal, said connection circuit connecting said first and second input terminals to said first and second output terminals, respectively, in synchronism with the rise of said pulse signal whereas said first input terminal is connected to said second output terminal and said second input terminal to said first output terminal in synchronism with the fall of said pulse signal;
a current generator circuit which receives said first and second detection signals from said first and second output terminals, respectively, to generate a current representing the difference between the levels of said signals; and
an integrator circuit for integrating the output current from said current generator circuit, a plurality of said first capacitors being provided in a detection portion of the locator device and continuously selected in succession. - View Dependent Claims (5, 6, 7)
- a first and a second capacitor;
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8. A locator device comprising:
- a touch detecting portion having multiple electrodes arranged in a specified direction and a common electrode placed in a face-to-face relationship with said multiple electrodes;
a pulse drive circuit which drives said common electrode in response to a pulse signal and with which two capacitors formed by a pair of adjacent electrodes selected in synchronism with either the rise or fall of the applied pulse are charged or discharged to generate a first and a second detection signal in said pair of electrodes;
a multiplexer which sequentially selects said pair of adjacent electrodes to receive said first and second detection signals;
a current generator circuit which receives said first and second detection signals from said multiplexer to generate a current representing the difference between the levels of said signals;
an integrator circuit which integrates the output current form said current generator circuit;
reference level sampling means by which the voltage value of said integrator circuit which is obtained by sequentially selecting said pair of electrodes as a group with said multiplexer when neither of said electrodes in pair are touched is stored in correspondence with said selected electrode pair;
cumulative value computing means which calculates a correction value by subtracting A from B, B being the voltage value of said integrator circuit obtained for said electrode pair selected by sequential selection with said multiplexer when either of said electrodes in pair is touched and A being the voltage value of said integrator circuit stored by said reference level sampling means in correspondence with said selected electrode pair, and which accumulates the calculated correction value for each updating of the selection of said electrode pair and which stores the cumulative value in correspondence with said updated electrode pair; and
touch position detecting means by which said electrode pair which corresponds to a maximum of the cumulative values calculated by said cumulative value computing means or either one of said electrodes in pair is taken as the touched electrode and its position is detected. - View Dependent Claims (9, 10, 11, 12)
- a touch detecting portion having multiple electrodes arranged in a specified direction and a common electrode placed in a face-to-face relationship with said multiple electrodes;
Specification