Ultrasonic sensor system and method having automatic excitation frequency adjustment
First Claim
1. An ultrasonic sensor system comprising:
- transducer means for emitting an ultrasonic signal in response to an electrical excitation signal and for outputting an electrical response signal in response to receipt of a reflected ultrasonic signal from an object, said transducer means rings-down upon termination of the electrical excitation signal, and said transducer means having a natural resonant frequency which is subject to change;
excitation signal provision means for providing the electrical excitation signal to said transducer means;
processing means for processing the electrical response signal resulting from excitation of said transducer means by the electrical excitation signal at a predetermined frequency for determining distance between said transducer means and the object;
frequency variation means for varying the frequency of the electrical excitation signal over a range of frequencies;
monitor means for monitoring the ringdown of said transducer means during the variation of the frequency of the electrical excitation signal over the range of frequencies and for determining a current natural resonant frequency of said transducer means; and
adjustment means for changing the predetermined frequency to the determined natural resonant frequency.
2 Assignments
0 Petitions
Accused Products
Abstract
An ultrasonic sensor system (40) has a transducer (44) that emits an ultrasonic signal (52), in response to an electrical excitation signal (50) from driver/receiver circuitry (46), and outputs an electrical response signal (56), in response to receipt of a reflected ultrasonic signal (54) from an occupant (54). The transducer (44) rings-down upon termination of the excitation signal (50). The transducer (44) has a natural resonant frequency that is subject to change. In an occupant sense mode, a receiver portion (68) of the driver/receiver circuitry (46) and a controller (30) process the response signal (56), resulting from transducer excitation at a predetermined frequency, to determining distance between the transducer (44) and the occupant (14). In an adjust mode, the controller (30) varies the frequency of the excitation signal (50) over a range of frequencies, and monitors the ringdown of the transducer (44) during the variation of the frequency to determine a current natural resonant frequency of the transducer (44). The controller (30) changes the predetermined frequency to the determined natural resonant frequency, so that subsequent operation in the sense mode utilizes the resonant frequency.
66 Citations
22 Claims
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1. An ultrasonic sensor system comprising:
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transducer means for emitting an ultrasonic signal in response to an electrical excitation signal and for outputting an electrical response signal in response to receipt of a reflected ultrasonic signal from an object, said transducer means rings-down upon termination of the electrical excitation signal, and said transducer means having a natural resonant frequency which is subject to change; excitation signal provision means for providing the electrical excitation signal to said transducer means; processing means for processing the electrical response signal resulting from excitation of said transducer means by the electrical excitation signal at a predetermined frequency for determining distance between said transducer means and the object; frequency variation means for varying the frequency of the electrical excitation signal over a range of frequencies; monitor means for monitoring the ringdown of said transducer means during the variation of the frequency of the electrical excitation signal over the range of frequencies and for determining a current natural resonant frequency of said transducer means; and adjustment means for changing the predetermined frequency to the determined natural resonant frequency. - View Dependent Claims (11)
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2. An ultrasonic sensor system comprising:
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transducer means for emitting an ultrasonic signal in response to an electrical excitation signal and for outputting an electrical response signal in response to receipt of a reflected ultrasonic signal from an object, said transducer means rings-down upon termination of the electrical excitation signal, and said transducer means having a natural resonant frequency which is subject to change; excitation signal provision means for providing the electrical excitation signal to said transducer means; processing means for processing the electrical response signal resulting from excitation of said transducer means by the electrical excitation signal at a predetermined frequency for determining distance between said transducer means and the object; frequency variation means for varying the frequency of the electrical excitation signal over a range of frequencies; monitor means for monitoring the ringdown of said transducer means during the variation of the frequency of the electrical excitation signal over the range of frequencies and for determining a current natural resonant frequency of said transducer means; and adjustment means for changing the predetermined frequency to the determined natural resonant frequency; said monitor means including means for monitoring a ringdown characteristic indicative of the duration of the ringdown of said transducer means. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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9. An ultrasonic sensor system comprising:
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transducer means for emitting an ultrasonic signal in response to an electrical excitation signal and for outputting an electrical response signal in response to receipt of a reflected ultrasonic signal from an object, said transducer means rings-down upon termination of the electrical excitation signal, and said transducer means having a natural resonant frequency which is subject to change; excitation signal provision means for providing the electrical excitation signal to said transducer means; processing means for processing the electrical response signal resulting from excitation of said transducer means by the electrical excitation signal at a predetermined frequency for determining distance between said transducer means and the object; frequency variation means for varying the frequency of the electrical excitation signal over a range of frequencies; monitor means for monitoring the ringdown of said transducer means during the variation of the frequency of the electrical excitation signal over the range of frequencies and for determining a current natural resonant frequency of said transducer means; and adjustment means for changing the predetermined frequency to the determined natural resonant frequency; said excitation signal provision means including means for providing a low power excitation signal to said transducer means, the low power excitation signal having sufficient strength to cause ringdown of said transducer means and having insufficient strength to cause a reflected ultrasonic signal, said monitor means monitors the ringdown of said transducer means caused by the low power excitation. - View Dependent Claims (10)
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12. A method of ultrasonic sensing with automatic excitation frequency adjustment, said method comprising:
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providing an electrical excitation signal to a transducer means; emitting an ultrasonic signal from the transducer means in response to the electrical excitation signal, the transducer means rings-down upon termination of the electrical excitation signal, and the transducer means having a natural resonant frequency which is subject to change; outputting an electrical response signal in response to receipt of a reflected ultrasonic signal from an object; processing the electrical response signal resulting from excitation of the transducer means by the electrical excitation signal at a predetermined frequency for determining distance between the transducer means and the object; varying the frequency of the electrical excitation signal over a range of frequencies; monitoring the ringdown of the transducer means during the variation of the frequency of the electrical excitation signal over the range of frequencies; determining a current natural resonant frequency of the transducer means; and changing the predetermined frequency to the determined natural resonant frequency. - View Dependent Claims (22)
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13. A method of ultrasonic sensing with automatic excitation frequency adjustment, said method comprising:
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providing an electrical excitation signal to a transducer means; emitting an ultrasonic signal from the transducer means in response to the electrical excitation signal, the transducer means rings-down upon termination of the electrical excitation signal, and the transducer means having a natural resonant frequency which is subject to change; outputting an electrical response signal in response to receipt of a reflected ultrasonic signal from an object; processing the electrical response signal resulting from excitation of the transducer means by the electrical excitation signal at a predetermined frequency for determining distance between the transducer means and the object; varying the frequency of the electrical excitation signal over a range of frequencies; monitoring the ringdown of the transducer means during the variation of the frequency of the electrical excitation signal over the range of frequencies; determining a current natural resonant frequency of the transducer means; and changing the predetermined frequency to the determined natural resonant frequency; said step of monitoring including monitoring a ringdown characteristic indicative of the duration of the ringdown of the transducer means. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A method of ultrasonic sensing with automatic excitation frequency adjustment, said method comprising:
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providing an electrical excitation signal to a transducer means; emitting an ultrasonic signal from the transducer means in response to the electrical excitation signal, the transducer means rings-down upon termination of the electrical excitation signal, and the transducer means having a natural resonant frequency which is subject to change; outputting an electrical response signal in response to receipt of a reflected ultrasonic signal from an object; processing the electrical response signal resulting from excitation of the transducer means by the electrical excitation signal at a predetermined frequency for determining distance between the transducer means and the object; varying the frequency of the electrical excitation signal over a range of frequencies; monitoring the ringdown of the transducer means during the variation of the frequency of the electrical excitation signal over the range of frequencies; determining a current natural resonant frequency of the transducer means; and changing the predetermined frequency to the determined natural resonant frequency; said step of providing an excitation signal includes providing a low power excitation signal to the transducer means, the low power excitation signal has sufficient strength to cause ringdown of the transducer means and has insufficient strength to cause a reflected ultrasonic signal, said step of monitoring includes monitoring the ringdown of the transducer means caused by the low power excitation. - View Dependent Claims (21)
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Specification