Multi-axis accelerometer comprising a mass suspended by springs above an optical sensor
First Claim
1. A multi-axis accelerometer comprising:
- (a) at least one optical sensor for generating a sensor signal in response to light illuminating the optical sensor;
(b) a mask positioned over the optical sensor for covering a first area of the optical sensor;
(c) at least one spring; and
(d) a mass suspended above the optical sensor by the spring, wherein;
the mass comprises at least one mass aperture for allowing the light to pass through the mass aperture and illuminate a second area of the optical sensor not covered by the mask; and
when the multi-axis accelerometer accelerates causing the mass to move, a corresponding movement of the mass aperture alters the illumination of the optical sensor such that the sensor signal is indicative of the acceleration.
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Abstract
A multi-axis accelerometer is disclosed comprising at least one optical sensor for generating a sensor signal in response to light illuminating the optical sensor, a mask positioned over the optical sensor for covering a first area of the optical sensor, at least one spring, and a mass suspended above the optical sensor by the spring. The mass comprises at least one mass aperture for allowing the light to pass through the mass aperture and illuminate a second area of the optical sensor not covered by the mask. When the multi-axis accelerometer accelerates causing the mass to move, a corresponding movement of the mass aperture alters the illumination of the optical sensor such that the sensor signal is indicative of the acceleration.
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Citations
28 Claims
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1. A multi-axis accelerometer comprising:
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(a) at least one optical sensor for generating a sensor signal in response to light illuminating the optical sensor;
(b) a mask positioned over the optical sensor for covering a first area of the optical sensor;
(c) at least one spring; and
(d) a mass suspended above the optical sensor by the spring, wherein;
the mass comprises at least one mass aperture for allowing the light to pass through the mass aperture and illuminate a second area of the optical sensor not covered by the mask; and
when the multi-axis accelerometer accelerates causing the mass to move, a corresponding movement of the mass aperture alters the illumination of the optical sensor such that the sensor signal is indicative of the acceleration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
(a) the at least one mass aperture comprises a plurality of linear apertures; and
(b) the mask comprises a corresponding plurality of opaque lines.
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4. The multi-axis accelerometer as recited in claim 1, wherein the at least one spring comprises a vertical wire having a first end connected to the mass and a second end connected to the optical sensor.
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5. The multi-axis accelerometer as recited in claim 1, wherein:
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(a) the at least one optical sensor comprises an A sensor, a B sensor, a C sensor and a D sensor;
(b) the A sensor generates an A sensor signal, the B sensor generates a B sensor signal, the C sensor generates a C sensor signal, and the D sensor generates a D sensor signal;
(c) a first linear acceleration is detected relative to the A sensor signal and the D sensor signal;
(d) a second linear acceleration is detected relative to the B sensor signal and the C sensor signal; and
(e) a rotational acceleration is detected relative to the A, B, C and D sensor signals.
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6. The multi-axis accelerometer as recited in claim 5, wherein:
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(a) the first linear acceleration is detected relative to a difference between the A sensor signal and the D sensor signal;
(b) the second linear acceleration is detected relative to a difference between the B sensor signal and the C sensor signal; and
(c) the rotational acceleration is detected relative to;
a first sum generated by summing the A sensor signal and the D sensor signal;
a second sum generated by summing the B sensor signal and the C sensor signal; and
a difference between the first sum and the second sum.
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7. The multi-axis accelerometer as recited in claim 1, further comprising:
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(a) a housing for creating a compartment between the optical sensor and the mass; and
(b) a fluid within the compartment for providing a damping effect.
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8. The multi-axis accelerometer as recited in claim 1, wherein:
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(a) the optical sensor and the mass are enclosed in a housing; and
(b) the at least one spring comprises a horizontal wire having a first end connected to the mass and a second end connected to the housing.
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9. A method of detecting linear and rotational accelerations, the method comprising the steps of:
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(a) positioning a mask over an optical sensor to cover a first area of the optical sensor;
(b) suspending a mass above the optical sensor using springs; and
(c) illuminating the optical sensor with light to generate a sensor signal;
wherein;
the mass comprises at least one mass aperture for allowing the light to pass through the mass aperture and illuminate a second area of the optical sensor not covered by the mask; and
when the multi-axis accelerometer accelerates causing the mass to move, a corresponding movement of the mass aperture alters the illumination of the optical sensor such that the sensor signal is indicative of the acceleration. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
(a) the at least one mass aperture comprises a plurality of linear apertures; and
(b) the mask comprises a corresponding plurality of opaque lines.
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12. The method as recited in claim 9, wherein the at least one spring comprises a vertical wire having a first end connected to the mass and a second end connected to the optical sensor.
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13. The method as recited in claim 9, wherein the at least one optical sensor comprises an A sensor, a B sensor, a C sensor and a D sensor, and the A sensor generates an A sensor signal, the B sensor generates a B sensor signal, the C sensor generates a C sensor signal, and the D sensor generates a D sensor signal, the method further comprises the steps of:
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(a) detecting a first linear acceleration relative to the A sensor signal and the D sensor signal;
(b) detecting a second linear acceleration relative to the B sensor signal and the C sensor signal; and
(c) detecting a rotational acceleration relative to the A, B, C and D sensor signals.
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14. The method as recited in claim 13, wherein:
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(a) the step of detecting the first linear acceleration comprises the step of computing a difference between the A sensor signal and the D sensor signal;
(b) the step of detecting the second linear acceleration comprises the step of computing a difference between the B sensor signal and the C sensor signal; and
(c) the step of computing the rotational acceleration comprises the steps of;
computing a first sum by summing the A sensor signal and the D sensor signal;
computing a second sum by summing the B sensor signal and the C sensor signal; and
computing a difference between the first sum and the second sum.
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15. The method as recited in claim 9, wherein:
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(a) the optical sensor and the mass are enclosed in a housing to create a compartment between the optical sensor and the mass; and
(b) the compartment is filled with a fluid to provide a damping effect.
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16. The method as recited in claim 9, wherein:
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(a) the optical sensor and the mass are enclosed in a housing; and
(b) the at least one spring comprises a horizontal wire having a first end connected to the mass and a second end connected to the housing.
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17. A disk drive comprising:
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(a) a disk;
(b) a head;
(c) an actuator for actuating the head radially over the disk;
(d) a multi-axis accelerometer for generating an acceleration signal representing a vibration affecting the actuator, the acceleration signal for controlling operation of the disk drive, the multi-axis accelerometer comprising;
at least one optical sensor for generating a sensor signal in response to light illuminating the optical sensor;
a mask positioned over the optical sensor for covering a first area of the optical sensor;
at least one spring; and
a mass suspended above the optical sensor by the spring, wherein;
the mass comprises at least one mass aperture for allowing the light to pass through the mass aperture and illuminate a second area of the optical sensor not covered by the mask; and
when the disk drive accelerates causing the mass to move, a corresponding movement of the mass aperture alters the illumination of the optical sensor such that the sensor signal is indicative of the acceleration. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
(a) the at least one mass aperture comprises a plurality of linear apertures; and
(b) the mask comprises a corresponding plurality of opaque lines.
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23. The disk drive as recited in claim 17, wherein the at least one spring comprises a vertical wire having a first end connected to the mass and a second end connected to the optical sensor.
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24. The disk drive as recited in claim 17, wherein:
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(a) the at least one optical sensor comprises an A sensor, a B sensor, a C sensor and a D sensor;
(b) the A sensor generates an A sensor signal, the B sensor generates a B sensor signal, (b) the C sensor generates a C sensor signal, and the D sensor generates a D sensor signal, (c) a first linear acceleration is detected relative to the A sensor signal and the D sensor signal;
(d) a second linear acceleration is detected relative to the B sensor signal and the C sensor signal; and
(e) a rotational acceleration is detected relative to the A, B, C and D sensor signals.
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25. The disk drive as recited in claim 24, wherein:
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(a) the first linear acceleration is detected relative to a difference between the A sensor signal and the D sensor signal;
(b) the second linear acceleration is detected relative to a difference between the B sensor signal and the C sensor signal; and
(c) the rotational acceleration is detected relative to;
a first sum signal generated by summing frequencies of the A sensor signal and the D sensor signal;
a second sum signal generated by summing frequencies of the B sensor signal and the C sensor signal; and
a difference between the first sum signal and the second sum signal.
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26. The disk drive as recited in claim 25, wherein the multi-axis accelerometer further comprises:
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(a) an A variable oscillator (VO) for generating an A oscillating signal in response to the A sensor signal;
(b) a B VO for generating a B oscillating signal in response to the B sensor signal;
(c) a C VO for generating a C oscillating signal in response to the C sensor signal;
(d) a D VO for generating a D oscillating signal in response to the D sensor signal;
(e) a first axis counter comprising an up count input responsive to the A oscillating signal and a down count input responsive to the D oscillating signal, the first axis counter for generating on output signal indicative of the first linear acceleration;
(f) a second axis counter comprising an up count input responsive to the B oscillating signal and a down count input responsive to the C oscillating signal, the second axis counter for generating on output signal indicative of the second linear acceleration; and
(g) a rotation counter comprising an up count input responsive to the A and D oscillating signals and a down count input responsive to the B and C oscillating signals, the rotation counter for generating an output signal indicative of the rotational acceleration.
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27. The disk drive as recited in claim 17, further comprising:
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(a) a housing for creating a compartment between the optical sensor and the mass; and
(b) a fluid within the compartment for providing a damping effect.
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28. The disk drive as recited in claim 17, wherein:
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(a) the optical sensor and the mass are enclosed in a housing; and
(b) the at least one spring comprises a horizontal wire having a first end connected to the mass and a second end connected to the housing.
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Specification