Acoustic wave touch detection circuit and method
First Claim
1. A method of detecting a touch on a touch responsive area comprising:
- generating an acoustic wave in the touch responsive area;
determining a value representing the time that the acoustic wave in the touch responsive area decays to a predetermined level in the absence of a touch to provide a reference;
generating a subsequent acoustic wave in the touch responsive area;
determining a subsequent value representing the time that the subsequent acoustic wave decays to the predetermined level;
comparing the subsequent value to the reference to determine whether the subsequent value represents a touch on the touch responsive area.
3 Assignments
0 Petitions
Accused Products
Abstract
A circuit for an acoustic wave switch or sensor having a resonant acoustic wave cavity detects a touch or sensed event using a time domain approach. The circuit includes a controller that drives an acoustic wave transducer to generate a resonant acoustic wave in the acoustic wave cavity during a first portion of a sampling cycle. In a second portion of the sampling cycle, the controller monitors the time that it takes for the acoustic wave signal from the transducer to decay to a predetermined level. Based on the decay time, the controller detects a sensed event, such as a touch on the acoustic wave switch/sensor.
131 Citations
87 Claims
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1. A method of detecting a touch on a touch responsive area comprising:
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generating an acoustic wave in the touch responsive area;
determining a value representing the time that the acoustic wave in the touch responsive area decays to a predetermined level in the absence of a touch to provide a reference;
generating a subsequent acoustic wave in the touch responsive area;
determining a subsequent value representing the time that the subsequent acoustic wave decays to the predetermined level;
comparing the subsequent value to the reference to determine whether the subsequent value represents a touch on the touch responsive area. - View Dependent Claims (2, 3)
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4. A method of detecting a touch on a touch responsive area comprising:
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generating an acoustic wave in the touch responsive area;
determining a value representing the time that the acoustic wave in the touch responsive area decays to a predetermined level in the absence of a touch to provide a reference;
generating a subsequent acoustic wave in the touch responsive area of the device;
determining a subsequent value representing the time that the subsequent acoustic wave decays to the predetermined level;
comparing the subsequent value to the reference to determine whether the subsequent value represents a touch on the touch responsive area; and
updating the reference based on the comparison of the subsequent value to the reference. - View Dependent Claims (5, 6)
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7. A method of detecting a touch on a touch responsive area comprising:
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generating an acoustic wave in the touch responsive area;
providing a signal representing the acoustic wave in the touch responsive area, the acoustic wave signal, in the absence of a touch on the touch responsive area, decaying to a predetermined level over a period of time and the acoustic wave signal, in the presence of a touch on the touch responsive area, decaying to the predetermined level over a shorter period of time;
determining a value representing the period of time that the acoustic wave signal decays to the predetermined value; and
comparing the determined value to a reference to detect a touch on the touch responsive area. - View Dependent Claims (8, 9, 10, 11)
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12. A method of detecting a touch on a touch responsive area comprising:
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generating an acoustic wave in the touch responsive area;
providing a signal representing the acoustic wave in the touch responsive area, the acoustic wave signal, in the absence of a touch on the touch responsive area, decaying to a predetermined level over a number of cycles of the signal and the acoustic wave signal, in the presence of a touch on the touch responsive area, decaying to the predetermined level over a smaller number of cycles;
counting the number of cycles of the signal having an amplitude above the predetermined level to provide a count; and
comparing the count to a reference to detect a touch on the touch responsive area. - View Dependent Claims (13, 14, 15)
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16. A method of detecting a touch on a touch responsive area comprising:
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generating an acoustic wave in the touch responsive area;
providing a signal representing the acoustic wave in the touch responsive area in a sampling cycle, the acoustic wave signal for a sampling cycle, in the absence of a touch on the touch responsive area, decaying to a predetermined level over a period of time and the acoustic wave signal for a sampling cycle, in the presence of a touch on the touch responsive area, decaying to the predetermined level over a shorter period of time;
comparing the acoustic wave signal for a sampling cycle to the predetermined level to generate a pulse when the amplitude of the signal is greater than the predetermined level;
counting a number of the pulses generated to provide a count for a sampling cycle; and
comparing the count for a sampling cycle to a reference to detect a touch. - View Dependent Claims (17, 18, 19, 20)
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21. A touch detection circuit for detecting a touch on a touch responsive acoustic wave cavity comprising:
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at least one transducer driven to generate an acoustic wave in the cavity during a sampling cycle and responsive to the acoustic wave to provide a signal representative thereof for the sampling cycle; and
a controller responsive to the acoustic wave signal to determine a number representing the period of time that the acoustic wave signal for a sampling cycle decays to a predetermined level, and the controller comparing the number for a sampling cycle to a touch reference to detect a presence of a touch on the acoustic wave cavity during the sampling cycle. - View Dependent Claims (22, 23, 25, 26, 27, 28, 29)
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24. A touch detection circuit as recited in 22 wherein the processor determines the touch reference based on at least one number representing the period of time that the acoustic wave signal for a sampling cycle decays to a predetermined level in the absence of a touch on the acoustic wave cavity.
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30. A touch detection circuit for detecting a touch on a touch responsive acoustic wave cavity comprising:
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at least one transducer to generate an acoustic wave in the cavity when the transducer is driven and responsive to the acoustic wave in the cavity to provide a signal representative thereof;
a controller that controls the driving of the at least one transducer and the receipt of the acoustic wave signal from the transducer during a sampling cycle, the controller being responsive to the transducer signal to determine a number representing the period of time that the signal, received from the transducer during a sampling cycle, decays to a predetermined level, and the controller comparing the number for a sampling cycle to a touch reference to detect the presence of a touch on the acoustic wave cavity during the sampling cycle.
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31. A touch detection circuit for detecting a touch on a touch responsive acoustic wave cavity comprising:
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at least one transducer driven to generate an acoustic wave in the cavity during a sampling cycle and responsive to the acoustic wave to provide a signal representative thereof for the sampling cycle;
a comparator for comparing the amplitude of the acoustic wave signal for a sampling cycle to a first reference to generate a pulse when the amplitude of the acoustic wave signal is above the first reference;
a counter for counting a number of the pulses from the comparator to provide a count for the sampling cycle; and
a processor for comparing the count for the sampling cycle to a second reference to detect a touch. - View Dependent Claims (32, 33, 34, 35, 36, 37)
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38. A touch detection circuit for detecting a touch on a touch responsive acoustic wave cavity comprising:
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an electromagnetic acoustic transducer having a coil and at least one magnet, the electromagnetic acoustic transducer being positioned adjacent the acoustic wave cavity; and
a controller coupled to the coil to drive the transducer to generate an acoustic wave in the acoustic wave cavity and to pick up a signal from the transducer representing the acoustic wave in the acoustic wave cavity, the controller is responsive to the signal to determine a value representing the period of time that the acoustic wave signal decays to a predetermined level, the value being indicative of the presence or absence of a touch on the touch responsive acoustic wave cavity. - View Dependent Claims (39, 40)
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41. A circuit for an acoustic wave sensor comprising:
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at least one transducer driven to generate a resonant acoustic wave in an acoustic wave resonator and responsive to the acoustic wave to provide a signal representative thereof;
a controller responsive to the signal for determining a value representing the period of time that the acoustic wave decays to a predetermined level, the controller comparing the value to a reference to sense an event.
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42. A method of sensing in an acoustic wave sensor comprising:
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generating a resonant acoustic wave;
providing a signal representing the resonant acoustic wave, the signal decaying over time;
determining a value representing the period of time that the acoustic wave decays to a predetermined level; and
comparing the value to a reference indicative of a sensed event.
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43. A method of detecting switch malfunction for an acoustic wave switch comprising:
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generating an acoustic wave in the acoustic wave switch;
providing a signal representing the acoustic wave in the acoustic wave switch;
determining a value representing the period of time that the acoustic wave decays to a predetermined level; and
comparing the determined value to a malfunction reference to determine whether the switch has malfunctioned. - View Dependent Claims (44, 45)
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46. A method of detecting switch malfunction for an acoustic wave switch comprising:
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generating an acoustic wave in the acoustic wave switch during each of a plurality of sampling periods;
providing a signal representing the acoustic wave in the acoustic wave switch in each of the sampling periods;
determining, for each of the sampling periods, a value representing the period of time that the acoustic wave decays to a predetermined level; and
comparing a plurality of the determined values to a reference to determine whether the switch has malfunctioned. - View Dependent Claims (47, 48)
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49. A method of detecting switch malfunction wherein switch failure is determined when the values for a predetermined number of consecutive sampling periods have been greater than or less than the reference.
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50. A method of detecting impending switch malfunction for an acoustic wave switch comprising:
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generating an acoustic wave in the acoustic wave switch during each of a plurality of sampling periods;
providing a signal representing the acoustic wave in the acoustic wave switch in each of the sampling periods;
determining, for each of the sampling periods, a value representing the period of time that the acoustic wave decays to a predetermined level;
determining a trend from a plurality of the determined values indicative of impending switch malfunction. - View Dependent Claims (51, 52)
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53. A method of detecting switch malfunction for an acoustic wave switch comprising:
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generating an acoustic wave in the acoustic wave switch during each of a plurality of sampling periods;
providing a signal representing the acoustic wave in the acoustic wave switch in each of the sampling periods;
determining, for each of the sampling periods, a first value representing the period of time that the acoustic wave decays to a predetermined level;
determining a second value representing an average of a plurality of the first values; and
comparing the second value to a reference to determine whether the switch has malfunctioned.
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54. A method of detecting liquid interference with an acoustic wave sensor comprising:
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generating an acoustic wave in the acoustic wave switch during each of a plurality of sampling periods the acoustic wave being insensitive to the liquid at certain levels of the liquid and the acoustic wave being sensitive to the liquid at other levels;
providing a signal representing the acoustic wave in the acoustic wave switch in each of the sampling periods; and
analyzing the signals in a predetermined number of consecutive sampling periods for variations among the signal indicative of the presence of an interfering liquid. - View Dependent Claims (55, 56)
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57. An acoustic wave touch panel comprising:
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a substrate having a plurality of wave cavities formed therein and defined by an area of increased mass, the substrate having a surface with touch responsive areas associated with the acoustic wave cavities and a back surface opposite thereto;
a transducer positioned adjacent the back surface of each of the acoustic wave cavities;
a circuit board having a circuit for driving the transducers to generate an acoustic wave in each of the acoustic wave cavities, the circuit board having a plurality of apertures and the circuit board being bonded on the back surface of the substrate wherein each aperture is aligned with a respective acoustic wave cavity. - View Dependent Claims (58, 59, 60, 61, 62, 63, 64)
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65. An acoustic wave sensor comprising:
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a substrate having an acoustic wave cavity defined by an area of increased mass, the acoustic wave cavity having a surface responsive to a sensed event and a back surface opposite thereto;
a transducer mounted on the back surface of the acoustic wave cavity; and
a circuit board with an aperture and a contact extending over the aperture, the circuit board being bonded onto the substrate with the aperture aligned with the acoustic wave cavity and the contact contacting the transducer. - View Dependent Claims (66, 67, 68, 69, 70)
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71. An acoustic wave sensor comprising:
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an acoustic wave cavity insert having an area of increased mass defining an acoustic wave cavity, the acoustic wave cavity having a surface responsive to an event to be sensed and a back surface opposite thereto and the insert having a periphery shaped to allow the acoustic wave cavity insert to be mounted in an aperture of a sensor support;
at least one transducer mounted on the back surface of the acoustic wave cavity of the insert. - View Dependent Claims (72, 73, 74, 75, 76, 77)
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78. An acoustic wave sensor component comprising:
a stamped insert having a raised area defining an acoustic wave cavity and a periphery spaced from the acoustic wave cavity and shaped to allow the acoustic wave insert to be mounted in an aperture of a sensor support. - View Dependent Claims (79, 80)
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81. An acoustic wave sensor component comprising:
a sensor disk having a raised area with a generally circular periphery formed thereon, the raised area defining an acoustic wave cavity, the sensor disk having a periphery spaced from the acoustic wave cavity and shaped to allow the sensor disk to be mounted in an aperture of a support for the sensor disk. - View Dependent Claims (82, 83, 84, 85, 86, 87)
Specification