US5517845A — Acceleration sensor having fault diagnosing device

Claim 1

Independent Claim 133 words

An acceleration sensor comprising: a piezoelectric element outputting a signal corresponding to acceleration applied to the piezoelectric element; signal processing means electrically connected to said piezoelectric element for processing the signal outputted from said piezoelectric element; alternating current signal outputting means electrically connected to said piezoelectric element for receiving an externally input timing signal and generating an alternating current signal which is synchronized with a period of the timing signal in response to receipt of the timing signal and for applying the alternating current signal to said piezoelectric element; a capacitor connected between said alternating current signal outputting means and said piezoelectric element; and a fault detecting means for detecting a fault in the acceleration sensor based on a relationship between a capacitance of the capacitor and a capacitance of the piezoelectric element.

Claim 2

Dependent Claim 133 words

An acceleration sensor comprising: a piezoelectric element outputting a signal corresponding to acceleration applied to the piezoelectric element; signal processing means electrically connected to said piezoelectric element for processing the signal outputted from said piezoelectric element; alternating current signal outputting means electrically connected to said piezoelectric element for receiving an externally input timing signal and generating an alternating current signal which is synchronized with a period of the timing signal in response to receipt of the timing signal and for applying the alternating current signal to said piezoelectric element; a capacitor connected between said alternating current signal outputting means and said piezoelectric element; and a fault detecting means for detecting a fault in the acceleration sensor based on a relationship between a capacitance of the capacitor and a capacitance of the piezoelectric element.

Claim 3

Dependent Claim 79 words

The acceleration sensor according to claim 1, wherein said signal processing means comprises: impedance converting means electrically connected to the piezoelectric element for converting an impedance of the signal outputted from the piezoelectric element to an impedance that matches an impedance of the signal processing means; filtering means electrically connected to the impedance converting means for removing an unnecessary signal component; and amplifying means electrically connected to said filtering means for amplifying a signal applied from the filtering means.

Claim 4

Dependent Claim 46 words

The acceleration sensor according to claim 1, wherein at least a part of said signal processing means is constituted by a single electronic component having a flat upper surface, said piezoelectric element being fixed to said upper surface of said electronic component in a cantilevered arrangement.

Claim 5

Dependent Claim 43 words

The acceleration sensor according to claim 1, which further comprises a temperature compensating capacitor arranged in close proximity to said piezoelectric element and connected in parallel to the piezoelectric element for compensating for a change in an ambient temperature of the acceleration sensor.

Claim 6

Dependent Claim 76 words

The acceleration sensor according to claim 1, wherein at least a part of said signal processing means is constituted by a single electronic component, and which further comprises a base plate for supporting said electronic component, a cushioning member for absorbing a thermal shock produced between the base plate and said electronic component due to the difference in coefficient of thermal expansion or modulus of elasticity being arranged between the base plate and the electronic component.

Claim 7

Dependent Claim 18 words

An acceleration sensor according to claim 1, wherein said fault detecting means is located within said acceleration sensor.

Claim 8

Dependent Claim 34 words

The acceleration sensor according to claim 1, wherein said capacitor is located such that said alternating current signal is applied from said alternating current signal outputting means through said capacitor to said piezoelectric element.

Claim 9

Dependent Claim 151 words

The acceleration sensor according to claim 1, wherein said signal processing means comprises a filtering means for removing an unnecessary signal component and said fault detecting means comprises a measuring and operating means for receiving a first voltage output from said signal processing means when said timing signal input to said alternating current signal outputting means has a frequency within a passband of said filtering means and a second voltage output from said signal processing means when said timing signal input to said alternating current signal outputting means has a frequency outside of said passband of said filtering means, said measuring and operating means comparing said first and second voltages to a desired value for each of said first and second voltages stored in said measuring and operating means and detecting a variation between said desired values and said first and second voltages to detect a fault in the acceleration sensor.

Claim 10

Dependent Claim 60 words

The acceleration sensor according to claim 8, wherein said first voltage signal and said second voltage signal are derived from the signal outputted from said piezoelectric element to said signal processing means multiplied by Q 2 /(Q 1 +Q 2 ) wherein Q 1 is the capacitance of the piezoelectric element and Q 2 is the capacitance of the capacitor.

Claim 11

Dependent Claim 16 words

The acceleration sensor according to claim 8, wherein said measuring and operating means comprises a microcomputer.

Claim 12

Dependent Claim 35 words

The acceleration sensor according to claim 1, further comprising a control means for starting a fault diagnostic operation of said fault detecting means by inputting a timing signal to said alternating current signal outputting means.

Claim 13

Dependent Claim 143 words

An acceleration sensor comprising: a piezoelectric element outputting a signal corresponding to acceleration applied to the piezoelectric element; a signal processor electrically connected to the piezoelectric element for processing the signal outputted from the piezoelectric element; an alternating current signal generator having an input terminal for receiving an externally input timing signal, the alternating current signal generator generating an alternating current signal which is synchronized with a period of the timing signal in response to receipt of the timing signal, the alternating current signal generator being electrically connected to the piezoelectric element for transmitting the alternating current signal to the piezoelectric element; a capacitor connected between the alternating current signal generator and the piezoelectric element; and a detector for detecting a state of the acceleration sensor based on a relation between a capacitance of the capacitor and a capacitance of the piezoelectric element.

Claim 14

Dependent Claim 143 words

An acceleration sensor comprising: a piezoelectric element outputting a signal corresponding to acceleration applied to the piezoelectric element; a signal processor electrically connected to the piezoelectric element for processing the signal outputted from the piezoelectric element; an alternating current signal generator having an input terminal for receiving an externally input timing signal, the alternating current signal generator generating an alternating current signal which is synchronized with a period of the timing signal in response to receipt of the timing signal, the alternating current signal generator being electrically connected to the piezoelectric element for transmitting the alternating current signal to the piezoelectric element; a capacitor connected between the alternating current signal generator and the piezoelectric element; and a detector for detecting a state of the acceleration sensor based on a relation between a capacitance of the capacitor and a capacitance of the piezoelectric element.

Claim 15

Dependent Claim 74 words

The acceleration sensor according to claim 12, wherein said signal processor comprises: an impedance converter electrically connected to the piezoelectric element for converting an impedance of the signal outputted from the piezoelectric element to an impedance that matches an impedance of the signal processor; a filter electrically connected to the impedance converter for removing an unnecessary signal component; and an amplifier electrically connected to the filter for amplifying a signal applied from the filter.

Claim 16

Dependent Claim 44 words

The acceleration sensor according to claim 12, wherein at least part of the signal processor is constituted by a single electronic component having a flat upper surface, the piezoelectric element being fixed to the upper surface of the electronic component in a cantilevered arrangement.

Claim 17

Dependent Claim 42 words

The acceleration sensor according to claim 12, further comprising a temperature compensating capacitor arranged in close proximity to the piezoelectric element and connected in parallel to the piezoelectric element for compensating for a change in an ambient temperature of the acceleration sensor.

Claim 18

Dependent Claim 72 words

The acceleration sensor of claim 12, wherein at least part of the signal processor is constituted by a single electronic component, the acceleration sensor further comprising a base plate for supporting the electronic component, a cushioning member for absorbing a thermal shock produced between the base plate and the electronic component due to the difference in coefficient of thermal expansion or modules of elasticity between the base plate and the electronic component.

Claim 19

Dependent Claim 16 words

The acceleration sensor according to claim 12, wherein the detector is located within the acceleration sensor.

Claim 20

Dependent Claim 33 words

The acceleration sensor according to claim 12, wherein the capacitor is located such that the alternating current signal is applied from the alternating current signal generator through the capacitor to the piezoelectric element.

Claim 21

Dependent Claim 141 words

The acceleration sensor according to claim 12, wherein the signal processor comprises a filter for removing an unnecessary signal component and the detector comprises a measuring and operating device for receiving a first voltage output from the signal processor when the timing signal input to the alternating current signal generator has a frequency within a passband of the filter and a second voltage output from the signal processor when the timing signal input to the alternating current signal generator has a frequency outside of the passband of the filter, the measuring and operating device comparing the first and second voltages to a desired value for each of the first and second voltages stored in the measuring and operating device and detecting a variation between the desired values and the first and second voltages to detect the state of the acceleration sensor.

Claim 22

Dependent Claim 59 words

The acceleration sensor according to claim 19, wherein the first voltage signal and the second voltage signal are derived from the signal outputted from the piezoelectric element to the signal processor multiplied by Q 2 /(Q 1 +Q 2 ), wherein Q 1 is the capacitance of the piezoelectric element and Q 2 is the capacitance of the capacitor.

Claim 23

Dependent Claim 16 words

The acceleration sensor according to claim 19, wherein the measuring and operating device comprises a microcomputer.

Claim 24

Dependent Claim 32 words

The acceleration sensor according to claims 12, further comprising a control unit for starting a fault diagnostic operation of the detector by inputting a timing signal to the alternating current signal generator.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-05-21	1999-11-20	2000-05-21	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-05-21	2003-11-20	2004-05-21	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-05-21	2007-11-20	2008-05-21	$7700.00	Window Closed / Lapsed

Acceleration sensor having fault diagnosing device

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