Physical quantity sensor

• US 10,393,523 B2
• Filed: 06/11/2015
• Issued: 08/27/2019
• Est. Priority Date: 06/12/2014
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Sugimoto, Kiyomasa, Yoshida, Naoki, Sakai, Minekazu, Kuzuya, Nobuaki
• Primary Examiner(s): Sinha, Tarun
• Application Number:
  US15/307,859
• Publication Number:
  US 20170059320A1
• Time in Patent Office: 1,538 Days
• Field of Search: 7350412
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719
• CPC Class Codes: G01C 19/5614 Signal processing
• CPC Class Codes: G01C 19/5628 Manufacturing; Trimming; Mounting; Housings
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: H01L 2224/32145 the bodies being stacked
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48145 the bodies being stacked
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/16195 Flat cap [not enclosing an internal cavity]

Abstract

A physical quantity sensor includes a detection unit outputting a detection signal corresponding to a vibration of a vibrating element in an angular velocity sensor, and a self-diagnostic unit self-diagnosing a detection environment of an acceleration sensor and the angular velocity sensor on a basis of the detection signal outputted by the detection unit.

Claims

1. A physical quantity sensor, comprising:

an acceleration sensor provided with a sensing portion outputting a sensor signal corresponding to acceleration;

an angular velocity sensor provided with a sensing portion having an oscillating body that oscillates in a predetermined direction, the sensing portion outputting a sensor signal corresponding to an angular velocity from the sensing portion,

at least one of the acceleration sensor and the angular velocity sensor being of a package structure, in which a cap portion is arranged in a sensor portion where the sensing portion is formed and the sensing portion is hermetically sealed in an airtight chamber defined between the sensor portion and the cap portion;

a case having a housing space set to a predetermined pressure and housing the acceleration sensor and the angular velocity sensor in the housing space;

a detection unit outputting a detection signal corresponding to an oscillation of the oscillating body in the angular velocity sensor;

a self-diagnostic unit self-diagnosing a detection environment of the angular velocity sensor on a basis of the detection signal outputted by the detection unit; and

a circuit board received in the housing space, wherein;

the acceleration sensor is stacked on the circuit board through an adhesive agent,

the circuit board includes the detection unit and the self-diagnostic unit,

the acceleration sensor is of the package structure and the airtight chamber is set to an atmospheric pressure,

the housing space is set to a vacuum pressure, and

a ratio of a volume of the airtight chamber with respect to a volume of the housing space is set to 1.0×

10<sup>−

7</sup> or higher.

2. A physical quantity sensor, comprising:

an acceleration sensor provided with a sensing portion outputting a sensor signal corresponding to acceleration;

an angular velocity sensor provided with a sensing portion having an oscillating body that oscillates in a predetermined direction, the sensing portion outputting a sensor signal corresponding to an angular velocity from the sensing portion,

at least one of the acceleration sensor and the angular velocity sensor being of a package structure, in which a cap portion is arranged in a sensor portion where the sensing portion is formed and the sensing portion is hermetically sealed in an airtight chamber defined between the sensor portion and the cap portion;

a case having a housing space set to a predetermined pressure and housing the acceleration sensor and the angular velocity sensor in the housing space;

a differential amplifier configured to output a detection signal corresponding to an oscillation of the oscillating body in the angular velocity sensor;

a self-diagnostic unit self-diagnosing a detection environment of the angular velocity sensor on a basis of the detection signal outputted by the differential amplifier; and

a circuit board received in the housing space, wherein;

the acceleration sensor is stacked on the circuit board through an adhesive agent,

the circuit board contains the differential amplifier and the self-diagnostic unit,

the angular velocity sensor is of the package structure and the airtight chamber is set to a vacuum pressure, and

the housing space is set to an atmospheric pressure.

4. The physical quantity sensor according to claim 2, wherein

a ratio of a volume of the airtight chamber with respect to a volume of the housing space is set to 1.0×

10<sup>−

7</sup> or higher.

6. The physical quantity sensor according to claim 2, wherein

the sensing portion of the angular velocity sensor includes vibrating elements, and

the detection environment is pressure around the vibrating elements.

7. The physical quantity sensor according to claim 6, wherein:

the differential amplifier is configured to output the detection signal representing variation in vibration state of the vibrating elements due to increase in impedance at the vibrating elements and decrease in vibration of the vibrating elements in response to occurrence of leakage in the package structure, and

the self-diagnostic unit is configured to determine that the detection environment is abnormal on determination that the variation in the vibration state is greater than a reference value.

8. The physical quantity sensor according to claim 7, wherein:

the differential amplifier is configured to detect an electric charge generated at the vibrating elements, and

the self-diagnostic unit is configured to determine that the detection environment is abnormal on detection that the electric charge is reduced by a reference level or more, which is caused by increase in impedance at the vibrating elements in response to reduction in vibration of the vibrating elements due to pressure in the package structure that rises in response to occurrence of leakage at the package structure.

9. The physical quantity sensor according to claim 6, further comprising:

a charge amplifier; and

a window comparator, wherein;

the charge amplifier is connected to the vibrating elements and configured to convert an electric charge generated by vibrations of the vibrating elements to a voltage signal,

the differential amplifier is configured to input the voltage signal from the charge amplifier and to output a difference signal, which is a difference between the voltage signal and a reference voltage, corresponding to the detection environment of the vibrating elements,

the window comparator is configured to input the difference signal from the differential amplifier and to determine whether the difference signal falls within a normal voltage range, and

the window comparator is configured to, on determination that the difference signal falls outside the normal voltage range, output a voltage meaning abnormality as a diagnostic detection signal.

10. The physical quantity sensor according to claim 2, wherein

the acceleration sensor is of the package structure and the airtight chamber of the acceleration sensor is set to a vacuum pressure.

3. A physical quantity sensor, comprising:

an acceleration sensor provided with a sensing portion outputting a sensor signal corresponding to acceleration;

an angular velocity sensor provided with a sensing portion having an oscillating body that oscillates in a predetermined direction, the sensing portion outputting a sensor signal corresponding to an angular velocity from the sensing portion,

at least one of the acceleration sensor and the angular velocity sensor being of a package structure, in which a cap portion is arranged in a sensor portion where the sensing portion is formed and the sensing portion is hermetically sealed in an airtight chamber defined between the sensor portion and the cap portion;

a case having a housing space set to a predetermined pressure and housing the acceleration sensor and the angular velocity sensor in the housing space;

a differential amplifier configured to output a detection signal corresponding to an oscillation of the oscillating body in the angular velocity sensor;

a self-diagnostic unit configured to self-diagnose a detection environment of the angular velocity sensor on a basis of the detection signal outputted by the differential amplifier; and

a circuit board received in the housing space, wherein;

the acceleration sensor is stacked on the circuit board through an adhesive agent,

the circuit board contains the differential amplifier and the self diagnostic unit,

the angular velocity sensor is of the package structure and the airtight chamber of the angular velocity sensor is set to a vacuum pressure, and

the acceleration sensor is of the package structure and the airtight chamber of the acceleration sensor is set to an atmospheric pressure.

5. The physical quantity sensor according to claim 3, wherein

a ratio of a volume of the airtight chamber with respect to a volume of the housing space is set to 1.0×

10<sup>−

7</sup> or higher.

11. The physical quantity sensor according to claim 3, wherein:

the sensing portion of the angular velocity sensor includes vibrating elements, and

the detection environment is pressure around the vibrating elements.

12. The physical quantity sensor according to claim 11, wherein:

the differential amplifier is configured to output the detection signal representing variation in vibration state of the vibrating elements due to increase in impedance at the vibrating elements and decrease in vibration of the vibrating elements in response to occurrence of leakage in the package structure, and

the self-diagnostic unit is configured to determine that the detection environment is abnormal on determination that the variation in the vibration state is greater than a reference value.

13. The physical quantity sensor according to claim 12, wherein:

the differential amplifier is configured to detect an electric charge generated at the vibrating elements, and

the self-diagnostic unit is configured to determine that the detection environment is abnormal on detection that the electric charge is reduced by a reference level or more, which is caused by increase in impedance at the vibrating elements in response to reduction in vibration of the vibrating elements due to pressure in the package structure that rises in response to occurrence of leakage at the package structure.

14. The physical quantity sensor according to claim 11, further comprising:

a charge amplifier; and

a window comparator, wherein;

the charge amplifier is connected to the vibrating elements and configured to convert an electric charge generated by vibrations of the vibrating elements to a voltage signal,

the differential amplifier is configured to input the voltage signal from the charge amplifier and to output a difference signal, which is a difference between the voltage signal and a reference voltage, corresponding to the detection environment of the vibrating elements,

the window comparator is configured to input the difference signal from the differential amplifier and to determine whether the difference signal falls within a normal voltage range, and

the window comparator is configured to, on determination that the difference signal falls outside the normal voltage range, output a voltage meaning abnormality as a diagnostic detection signal.

15. The physical quantity sensor according to claim 3, wherein

the housing space is set to an atmospheric pressure.