US 2015/0084652 A1Published application

Module and Capacitance Detecting Method

AssigneeMurata Manufacturing Co., Ltd.

InventorsShoji Nagumo, Masashi Nakazato, Yujie Dai, Xiaoxing Zhang, Yingjie Lu

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Abstract

A capacitance detecting circuit includes a constant current source supplying a constant current to a voltage detection point, a time measuring unit measuring time of charge until the voltage of the voltage detection point reaches a prescribed voltage, a storage unit and an operation unit. The storage unit stores first data obtained in advance concerning the time of charge of a capacitance element having a known capacitance value, and second data obtained in advance concerning the time of charge of a capacitance component. The operation unit generates third data representing the time of charge of an object of detection from a difference between the first measurement value of the time measuring unit when the capacitance component is connected to the voltage detection point and the second data, and based on the ratio between the third data and the first data and the known capacitance value, calculates the capacitance value of the object of detection.

Claims14

Dependent claims

A module, comprising:

(a) a current path connected to an object of detection and including a capacitance component;
and
(b) a capacitance detecting circuit supplying a constant current to said object of detection through said current path, for determining a capacitance value of said object of detection, said capacitance value detecting circuit including:
(1) a constant current source supplying said constant current to a voltage detection point;
(2) a storage unit storing:
(a) first data, obtained in advance of said determination of said capacitance value, concerning a time it takes to charge a capacitance element having a known capacitance value to said prescribed voltage when said constant current is applied to said capacitance element and (b) second data, obtained in advance of said detection of said capacitance value, concerning a time it takes to charge said capacitance component to said prescribed voltage when said constant current is applied to said capacitive component;
(3) a charge/discharge circuit connecting said current path to said voltage detection point to charge both said object of detection and said capacitance component, and disconnecting said current path from said voltage detection point to discharge both said object of detection and said capacitance component;
(4) a time measuring circuit generating a third data indicative of a time it takes to charge said object of detection and said capacitance component with said constant current to cause said voltage detection point to attain said prescribed voltage;
and
(5) an operation unit:
(a) generating fourth data representing a time it takes to charge said object of detection from a difference between said third data and said second data;
and
(b) calculating a capacitance value of said object of detection based on a ratio between said third data and said first data.

10 more elements

A capacitance detecting method of determining a capacitance value of an object of detection connected to a current path including a capacitance component comprising:

supplying a constant current to a voltage detection point;
storing:
(a) first data, obtained in advance of said determination of said capacitance value, concerning a time it takes to charge a capacitance element having a known capacitance value to said prescribed voltage when said constant current is applied to said capacitance element and (b) second data, obtained in advance of said detection of said capacitance value, concerning a time it takes to charge said capacitance component to said prescribed voltage when said constant current is applied to said capacitive component;
connecting said current path to said voltage detection point to charge both said object of detection and said capacitance component, and subsequently disconnecting said current path from said voltage detection point to discharge both said object of detection and said capacitance component;
generating a third data indicative of a time it takes to charge said object of detection and said capacitance component with said constant current to cause said voltage detection point to attain said prescribed voltage;
generating fourth data representing a time it takes to charge said object of detection from a difference between said third data and said second data;
and
calculating a capacitance value of said object of detection based on a ratio between said third data and said first data.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/509,896Filed 8 Oct 2014
Priority: 30 May 2012
Published: 26 Mar 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01R 27/2605
Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric…:…
H03K 17/955
Proximity switches: using a capacitive detector
H03K 2217/960745
Characterised by circuit details: capacitive differential; e.g. comparison with reference capacitance
G01R
Measuring electric variables