INSPECTION METHOD OF SENSOR DEVICE AND SENSOR DEVICE

• US 20150253372A1
• Filed: 02/27/2015
• Published: 09/10/2015
• Est. Priority Date: 03/06/2014
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: YANAGI, Shuji, YOKOYAMA, Shinya, WATANABE, Takuya, OKI, Toshiyuki, ASAO, Akira
• Granted Patent: US 9,658,270 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01N 27/228 Circuits therefor measuring capacitance per se G01R27/26
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24
• CPC Class Codes: G01R 31/2829 Testing of circuits in sensor or actuator systems testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844
• CPC Class Codes: G01R 31/50 Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections testing of sparking plugs H01T13/58
• CPC Class Codes: G01R 31/67 Testing the correctness of wire connections in electric apparatus or circuits
• CPC Class Codes: H01L 2221/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
• CPC Class Codes: H04L 1/00 Arrangements for detecting or preventing errors in the information received correcting synchronisation H04L7/00
• CPC Class Codes: H04L 2201/00 Algorithms used for the adjustment of time-domain equalizers

Abstract

In a reset period of a first stage, a switching circuit is turned on, and high-level driving voltages are output from driving circuits. In a charge transfer period subsequent to the reset period, the switching circuit is turned off, and low-level driving voltages are output from the driving circuits. It is determined whether or not an output voltage of an amplifier circuit in the charge transfer period is included in a normal range. In the inspection of a second stage subsequent to the first stage, in the same manner as in the normal measurement, voltages having opposite phases are output from the driving circuits in the reset period and the charge transfer period, and it is determined whether or not the output voltage of the amplifier circuit in the charge transfer period is included in a normal range.

Claims

1. An inspection method of a sensor device, comprising:

a first step of discharging a capacitor by using a switching circuit and outputting a first driving voltage from both of first and second driving circuits;

a second step of releasing the discharge of the capacitor by the switching circuit and outputting a second driving voltage from both of the first and second driving circuits; and

a third step of determining whether or not a voltage output from an amplifier circuit in the second step is included in a first normal range,

wherein a first inspection stage includes the first step, the second step, and the third step, and

the sensor device includes;

a sensor unit including a first capacitive sensor element connected between a first driving terminal and a signal terminal and a second capacitive sensor element connected between a second driving terminal and the signal terminal;

the first driving circuit configured to output the first driving voltage or the second driving voltage to the first driving terminal;

the second driving circuit configured to output the first driving voltage or the second driving voltage to the second driving terminal;

the capacitor having an end connected to the signal terminal;

the amplifier circuit configured to output a voltage, which is obtained by amplifying a difference between a voltage of the signal terminal and a reference voltage, to the other end of the capacitor so that the voltage of the signal terminal becomes close to the reference voltage; and

the switching circuit configured to discharge electric charges accumulated in the capacitor.

2. The inspection method of a sensor device according to claim 1, further comprising:

a fourth step of discharging the capacitor by using the switching circuit and outputting the first driving voltage from the first driving circuit and the second driving voltage from the second driving circuit;

a fifth step of releasing the discharge of the capacitor by the switching circuit and outputting the second driving voltage from the first driving circuit and the first driving voltage from the second driving circuit; and

a sixth step of determining whether or not a voltage output from the amplifier circuit in the fifth step is included in a second normal range,

wherein a second inspection stage includes the fourth step, the fifth step, and the sixth step, and is performed when it is determined that the output voltage of the amplifier circuit in the first inspection stage is included in the first normal range.

3. The inspection method of a sensor device according to claim 2,

wherein the sensor device includes an offset adjustment circuit configured to adjust an offset voltage of the amplifier circuit,

in the first inspection stage, a function of adjusting the offset voltage by the offset adjustment circuit is disabled, and

in the second inspection stage, the function of adjusting the offset voltage by the offset adjustment circuit is enabled.

4. A sensor device, comprising:

a sensor unit including a first capacitive sensor element connected between a first driving terminal and a signal terminal and a second capacitive sensor element connected between a second driving terminal and the signal terminal;

a first driving circuit configured to output a first driving voltage or a second driving voltage to the first driving terminal;

a second driving circuit configured to output the first driving voltage or the second driving voltage to the second driving terminal;

a capacitor having an end connected to the signal terminal;

an amplifier circuit configured to output a voltage, which is obtained by amplifying a difference between a voltage of the signal terminal and a reference voltage, to the other end of the capacitor so that the voltage of the signal terminal becomes close to the reference voltage;

a switching circuit configured to discharge electric charges accumulated in the capacitor; and

a control circuit configured to control the first driving circuit, the second driving circuit, and the switching circuit so that a voltage corresponding to a difference between a capacitance of the first capacitive sensor element and a capacitance of the second capacitive sensor element is output from the amplifier circuit,

wherein the control circuit executes;

a first step of discharging the capacitor by using the switching circuit and outputting the first driving voltage from both of the first and second driving circuits;

a second step of releasing the discharge of the capacitor by the switching circuit and outputting the second driving voltage from both of the first and second driving circuits; and

a third step of determining whether or not the voltage output from the amplifier circuit in the second step is included in a first normal range, and

a first inspection stage includes the first step, the second step, and the third step.

5. The sensor device according to claim 4,

wherein the control circuit executes:

a fourth step of discharging the capacitor by using the switching circuit and outputting the first driving voltage from the first driving circuit and the second driving voltage from the second driving circuit;

a fifth step of releasing the discharge of the capacitor by the switching circuit and outputting the second driving voltage from the first driving circuit and the first driving voltage from the second driving circuit; and

a sixth step of determining whether or not a voltage output from the amplifier circuit in the fifth step is included in a second normal range, and

a second inspection stage includes the fourth step, the fifth step, and the sixth step, and is performed when it is determined that the output voltage of the amplifier circuit in the first inspection stage is included in the first normal range.

6. The sensor device according to claim 5, further comprising:

an offset adjustment circuit configured to adjust an offset voltage of the amplifier circuit,

wherein the control circuit disables a function of adjusting the offset voltage by the offset adjustment circuit in the first inspection stage, and enables the function of adjusting the offset voltage by the offset adjustment circuit in the second inspection stage.