Optical proximity sensors with offset compensation
First Claim
1. An optical proximity sensor used to detect the presence, proximity and/or motion of an object within a sense region of the optical proximity sensor, comprising:
- a driver that selectively drives a light source to transmit light;
a light detector that produces an analog detection signal indicative of an intensity of light detected by the light detector, wherein the light detected by the light detector includeslight transmitted by the light source that reflected off an object within the sense region of the optical proximity sensor,interference light, which comprises light transmitted by the light source, and detected by the light detector, that did not reflect off an object within the sense region of the optical proximity sensor, andambient light;
an offset signal generator that selectively produces an analog offset signal that is combined with the analog detection signal produced by the photodetector to produce an analog compensated detection signal; and
an analog-to-digital converter (ADC) that converts the analog compensated detection signal to a digital compensated detection signal;
wherein the analog offset signal compensates for at least a portion of the interference light included in the light detected by the light detector; and
wherein a dynamic range of the ADC is increased by the analog offset signal being combined with the analog detection signal to produce the analog compensated detection signal upstream of the ADC, compared to if the analog offset signal is not combined with the analog detection signal to produce the analog compensated detection signal upstream of the ADC.
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Accused Products
Abstract
An optical proximity sensor includes a driver, light detector and offset signal generator. The driver selectively drives a light source. The light detector produces an analog detection signal indicative of an intensity of light detected by the light detector. The detected light can include light transmitted by the light source that reflected off an object within the sense region of the optical sensor, interference light and ambient light. The interference light includes light transmitted by the light source, and detected by the light detector, that was not reflected off an object within the sense region of the optical sensor. The offset signal generator selectively produces an analog offset signal that is combined with the analog detection signal produced by the photodetector to produce an analog compensated detection signal. The analog offset signal compensates for at least a portion of the interference light included in the light detected by the photodetector.
40 Citations
18 Claims
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1. An optical proximity sensor used to detect the presence, proximity and/or motion of an object within a sense region of the optical proximity sensor, comprising:
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a driver that selectively drives a light source to transmit light; a light detector that produces an analog detection signal indicative of an intensity of light detected by the light detector, wherein the light detected by the light detector includes light transmitted by the light source that reflected off an object within the sense region of the optical proximity sensor, interference light, which comprises light transmitted by the light source, and detected by the light detector, that did not reflect off an object within the sense region of the optical proximity sensor, and ambient light; an offset signal generator that selectively produces an analog offset signal that is combined with the analog detection signal produced by the photodetector to produce an analog compensated detection signal; and an analog-to-digital converter (ADC) that converts the analog compensated detection signal to a digital compensated detection signal; wherein the analog offset signal compensates for at least a portion of the interference light included in the light detected by the light detector; and wherein a dynamic range of the ADC is increased by the analog offset signal being combined with the analog detection signal to produce the analog compensated detection signal upstream of the ADC, compared to if the analog offset signal is not combined with the analog detection signal to produce the analog compensated detection signal upstream of the ADC. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for use with an optical proximity sensor, including a light source and a light detector, used to detect the presence, proximity and/or motion of an object within the sense region of the optical proximity sensor, the method comprising:
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(a) selectively driving the light source to thereby cause the light source to selectively transmit light; (b) producing an analog detection signal indicative of an intensity of light detected by the light detector, wherein the light detected by the light detector includes light transmitted by the light source that reflected off an object within the sense region of the optical proximity sensor, interference light, which comprises light transmitted by the light source, and detected by the light detector, that did not reflect off an object within the sense region of the optical proximity sensor, and ambient light; (c) producing an analog offset signal; (d) combining the analog offset signal with the analog detection signal to produce an analog compensated detection signal; and (e) converting the analog compensated detection signal to a digital compensated detection using an analog-to-digital converter (ADC); wherein the analog offset signal compensates for at least a portion of the interference light included in the light detected by the light detector; and wherein the analog offset signal is combined with the analog detection signal to produce the analog compensated detection signal prior to the converting at step (e), which increases a dynamic range of the ADC used to perform the converting at step (e) compared to if the analog offset signal is not combined with the analog detection signal to produce the analog compensated detection signal prior to the converting at step (e). - View Dependent Claims (11, 13, 14)
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12. A method for use with an optical proximity sensor, including a light source and a light detector, used to detect the presence, proximity and/or motion of an object within the sense region of the optical proximity sensor, the method comprising:
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(a) selectively driving the light source to thereby cause the light source to selectively transmit light; (b) producing an analog detection signal indicative of an intensity of light detected by the light detector, wherein the light detected by the light detector includes light transmitted by the light source that reflected off an object within the sense region of the optical proximity sensor, interference light, which comprises light transmitted by the light source, and detected by the light detector, that did not reflect off an object within the sense region of the optical proximity sensor, and ambient light; (c) producing an analog offset signal; and (d) combining the analog offset signal with the analog detection signal to produce an analog compensated detection signal; and wherein the analog offset signal compensates for at least a portion of the interference light included in the light detected by the light detector; and wherein step (c) comprises; (c.1) storing a first digital value for use in compensating for the interference light; (c.2) storing a second digital value for use in rejecting the ambient light; and (c.3) converting the first and second digital values to the analog offset signal; wherein the analog offset signal compensated for at least a portion of the interference light, and rejects at least a portion of the ambient light, included in the light detected by the light detector.
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15. A system comprising,
an optical proximity sensor to detect the presence, proximity and/or motion of an object within a sense region of the optical proximity sensor; -
a subsystem capable of being enabled and disabled; and a comparator or processor that receives a digital output of the optical proximity sensor and enables and disables the subsystem based on the digital output of the optical proximity sensor; wherein the optical proximity sensor includes a driver that selectively drives a light source to transmit light; a light detector that produces an analog detection signal indicative of an intensity of light detected by the light detector, wherein the light detected by the light detector includes light transmitted by the light source that reflected off an object within the sense region of the optical proximity sensor, interference light, which comprises light transmitted by the light source, and detected by the light detector, that did not reflect off an object within the sense region of the optical proximity sensor, and ambient light; an offset signal generator that selectively produces an analog offset signal that is combined with the analog detection signal produced by the photodetector to produce an analog compensated detection signal; an analog-to-digital converter (ADC) that converts the analog compensated detection signal to a digital compensated detection signal; and wherein the analog offset signal compensates for at least a portion of the interference light included in the light detected by the light detector; wherein the analog offset signal is combined with the analog detection signal to produce the analog compensated detection signal upstream of the ADC, which increases a dynamic range of the ADC compared to if the analog offset signal is not combined with the analog detection signal to produce the analog compensated detection signal upstream of the ADC; and wherein the digital compensated detection signal comprises the digital output of the optical proximity sensor. - View Dependent Claims (16, 17, 18)
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Specification