Method and apparatus for detecting operational failure of a digital accelerometer
First Claim
1. An apparatus comprising:
- an accelerometer for providing an analog acceleration signal indicative of sensed acceleration;
A/D converter means operatively connected to said accelerometer for providing a gate enable signal and for providing a plurality of pulse signals when the gate enable signal is in a first state, a pulse-density of the plurality of pulse signals being indicative of a value of the analog acceleration signal; and
means for detecting when at least one of the plurality of pulse signals does not occur when the gate enable signal is in the first state and for providing a signal indicative thereof;
wherein the gate enable signal is a pulse-width modulated signal in which the pulse-width is functionally related to the value of the analog acceleration signal and wherein said A/D converter means further includes means for ANDING said pulse-width modulated signal with a continuous clock signal.
2 Assignments
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Accused Products
Abstract
An apparatus includes an accelerometer (24) for providing an analog acceleration signal indicative of crash acceleration. A sigma-delta A/D converter (26) is operatively connected to the accelerometer (24) for providing a pulse-width-modulated gate enable signal (GES) with a value indicative of the acceleration signal. The GES signal is ANDED with a clock signal to produce a pulse-density signal (CNT) indicative of the acceleration signal. A monitoring circuit determines (i) whether at least one pulse-density signal occurs when a gate enable signal is HIGH (FLAG 1), and (ii) whether the pulse-density signal occurs when the gate enable signal is LOW (FLAG 2). Other embodiments test to see if the gate enable signal is either full scale ON (FLAG 3) or full scale OFF (FLAG 4) by using a second crash sensor (64). Timing circuits (302, 316) are used to ensure that the pulse duration of at least one pulse-width modulated gate enable signal is greater than predetermined value within a predetermined time period.
38 Citations
41 Claims
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1. An apparatus comprising:
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an accelerometer for providing an analog acceleration signal indicative of sensed acceleration; A/D converter means operatively connected to said accelerometer for providing a gate enable signal and for providing a plurality of pulse signals when the gate enable signal is in a first state, a pulse-density of the plurality of pulse signals being indicative of a value of the analog acceleration signal; and means for detecting when at least one of the plurality of pulse signals does not occur when the gate enable signal is in the first state and for providing a signal indicative thereof; wherein the gate enable signal is a pulse-width modulated signal in which the pulse-width is functionally related to the value of the analog acceleration signal and wherein said A/D converter means further includes means for ANDING said pulse-width modulated signal with a continuous clock signal.
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2. An apparatus comprising:
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an accelerometer for providing an analog acceleration signal having a value indicative of sensed acceleration; A/D converter means operatively connected to said accelerometer for outputting a gate enable signal having a first state with a signal value functionally related to the value of the acceleration signal, and for outputting a plurality of pulse signals with a pulse-density indicative of the value of the acceleration signal when said gate enable signal is in the first state; and means for detecting when at least one of the plurality of pulse signals does not occur when the gate enable signal is in the first state and for providing a signal indicative thereof. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus comprising:
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an accelerometer for providing an analog acceleration signal having a value indicative of sensed acceleration; A/D converter means operatively connected to said accelerometer for outputting a gate enable signal having a first state with a signal value functionally related to the value of the acceleration signal and a second state, and for outputting a plurality of pulse signals with a pulse-density indicative of the value of the acceleration signal when said gate enable signal is in the first state; and means for detecting when at least one of the plurality of pulse signals occurs when the gate enable signal is in the second state and for providing a signal indicative thereof. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. An method comprising:
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providing an analog acceleration signal from an accelerometer to A/D converter means, the acceleration signal having a value indicative of sensed acceleration; outputting a gate enable signal having a first state with a signal value functionally related to the value of the acceleration signal from the A/D converter means; outputting a plurality of pulse signals from the A/D converter means when the gate enable signal is in the first state, a pulse-density of the plurality of pulse signals being indicative of the value of the acceleration signal; and detecting when at least one of the plurality of pulse signals does not occur when the gate enable signal is in the first state. - View Dependent Claims (31, 32, 33, 34, 35)
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36. An method comprising:
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providing an analog acceleration signal from an accelerometer to A/D converter means, the acceleration signal having a value indicative of sensed acceleration; outputting a gate enable signal having a first state with a signal value functionally related to the value of the acceleration signal from the A/D converter means, the gate enable signal having a second state; outputting a plurality of pulse signals from the A/D converter means when said gate enable signal is in the first state, a pulse-density of the plurality of pulse signals being indicative of the value of the acceleration signal; and detecting when at least one of the plurality of pulse signals occurs when the gate enable signal is in the second state and for providing a signal indicative thereof. - View Dependent Claims (37, 38, 39, 40, 41)
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Specification