Proximity sensor
First Claim
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1. An electronic device having a front surface and including an ultrasonic proximity sensor arrangement comprising:
- an ultrasonic transmitter recessed from a front surface of the device;
an ultrasonic receiver recessed from the front surface of the device wherein the ultrasonic receiver is recessed further from the front surface of the device than the ultrasonic transmitter, forming a channel in which the ultrasonic receiver is positioned, wherein the channel comprises two discrete signal paths with first and second different lengths, the difference between the first and second lengths being substantially equal to an odd integer multiple of a wavelength of a signal transmitted from the ultrasonic transmitter; and
an acoustic barrier extending between the transmitter and receiver in the direction of the front surface of the device so as to block a direct path comprising ultrasonic signals travelling directly from the transmitter to the receiver,the ultrasonic proximity sensor arrangement being arranged to determine proximity of an object to said front surface based on an indirect signal received by the ultrasonic receiver, wherein the received indirect signal is a reflection from said object of a signal transmitted from the ultrasonic transmitter.
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Abstract
An electronic device (202) includes an ultrasonic proximity sensor arrangement comprising an ultrasonic transmitter (4) and an ultrasonic receiver (6) recessed from a front surface (208) of the device. A barrier (218) extends between the transmitter and receiver in the direction of the front surface of the device. The ultrasonic proximity sensor arrangement is arranged to determine proximity of an object (16) to said front surface based on a signal (214) received by the ultrasonic receiver, wherein the received signal is a reflection from said object of a signal transmitted from the ultrasonic transmitter.
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Citations
23 Claims
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1. An electronic device having a front surface and including an ultrasonic proximity sensor arrangement comprising:
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an ultrasonic transmitter recessed from a front surface of the device; an ultrasonic receiver recessed from the front surface of the device wherein the ultrasonic receiver is recessed further from the front surface of the device than the ultrasonic transmitter, forming a channel in which the ultrasonic receiver is positioned, wherein the channel comprises two discrete signal paths with first and second different lengths, the difference between the first and second lengths being substantially equal to an odd integer multiple of a wavelength of a signal transmitted from the ultrasonic transmitter; and an acoustic barrier extending between the transmitter and receiver in the direction of the front surface of the device so as to block a direct path comprising ultrasonic signals travelling directly from the transmitter to the receiver, the ultrasonic proximity sensor arrangement being arranged to determine proximity of an object to said front surface based on an indirect signal received by the ultrasonic receiver, wherein the received indirect signal is a reflection from said object of a signal transmitted from the ultrasonic transmitter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An electronic device having a front surface and including an ultrasonic proximity sensor arrangement comprising:
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an ultrasonic transmitter recessed from the front surface; an ultrasonic receiver recessed from the front surface; the ultrasonic proximity sensor arrangement being arranged to determine proximity of an object to said front surface based on a signal received by the ultrasonic receiver, wherein the received signal is a reflection from said object of a signal transmitted from the ultrasonic transmitter; the ultrasonic proximity sensor arrangement further comprising a structure disposed in front of the receiver defining at least first and second discrete signal paths having different path lengths such that signals travelling from the transmitter without passing the front surface to the receiver via the first and second paths undergo a destructive interference which is greater than a destructive interference undergone by signals travelling from the transmitter to the receiver after reflection from the object. - View Dependent Claims (18)
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17. An electronic device having a front surface and including an ultrasonic proximity sensor arrangement comprising:
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an ultrasonic transmitter recessed from the front surface; an ultrasonic receiver recessed from the front surface; the ultrasonic proximity sensor arrangement being arranged to determine proximity of an object to said front surface based on a signal received by the ultrasonic receiver, wherein the received signal is a reflection from said object of a signal transmitted from the ultrasonic transmitter; the ultrasonic proximity sensor arrangement further comprising a structure disposed in front of the transmitter defining at least first and second discrete signal paths having different path lengths such that signals travelling from the transmitter without passing the front surface to the receiver via the first and second paths undergo a destructive interference which is greater than a destructive interference undergone by signals travelling from the transmitter to the receiver after reflection from the object.
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19. A proximity sensor for an electronic device comprising an ultrasonic transmitter and an ultrasonic receiver in a common cavity arranged to determine proximity of an object to a front of said cavity based on a signal received by the ultrasonic receiver, wherein the received signal is a reflection from said object of a signal transmitted from the ultrasonic transmitter wherein the common cavity provides frequency-dependent attenuation to ultrasonic signals transmitted from the ultrasonic transmitter to the ultrasonic receiver with at least one attenuation frequency at which said frequency-dependent attenuation is a maximum within a predetermined frequency range, said ultrasonic signal having at least one dominant frequency substantially equal to said attenuation frequency.
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20. A method of calibrating a proximity sensor for an electronic device comprising an ultrasonic transmitter and an ultrasonic receiver in a common cavity, the method comprising:
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transmitting from the ultrasonic transmitter a plurality of ultrasonic test signals of different frequencies; receiving the plurality of ultrasonic test signals at the ultrasonic receiver; and determining from the received plurality of ultrasonic test signals an attenuation frequency corresponding to a maximum attenuation of the associated test signal between the transmitter and the receiver; and configuring said ultrasonic transmitter to transmit a proximity signal having at least one dominant frequency substantially equal to said attenuation frequency to determine proximity of an object to a front of said cavity based a signal received by the ultrasonic receiver, wherein the received signal is a reflection of said proximity signal from said object. - View Dependent Claims (21, 22, 23)
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Specification