Surface distance determination using time-of-flight of light
First Claim
1. A system comprising:
- a light emitter to emit light in pulses having a predetermined frequency;
at least one light sensor to capture, using a plurality of storage elements, energy from the light that is emitted from the light emitter and reflected off of a surface over a period of time including at least four time intervals, the plurality of storage elements including;
a first storage element to store energy from light captured during a first time interval that occurs for a length of time substantially equal to a duration of one of the pulses of light,a second storage element to store energy from light captured during a second time interval that occurs for a length of time substantially equal to an amount of time between each of the pulses,a third storage element to store energy from light captured during a third time interval that occurs during a portion of the first time interval, anda fourth storage element to store energy from light captured during a fourth time interval that occurs during a portion of the second time interval; and
one or more processors to calculate a distance between the at least one light sensor and the surface, the distance being within a distance range defined by a distance traveled by the light during a cycle of the predetermined frequency, the one or more processors calculating the distance based at least in part on;
a ratio of a measurement of the light stored during the first time interval and a measurement of the light stored during the second time interval, anda comparison of a measurement of the light stored during the third time interval and a measurement of the light stored during the fourth time interval.
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Accused Products
Abstract
In some embodiments, a distance between the at least one light sensor and the surface may be calculated using a ratio representative of the phase difference using time-of-flight of light. The distance may be within a distance range defined by a distance of light travel during a modulation period of the predetermined frequency. The distance may be based on the ratio defined by an amount of energy stored from captured light during a first time interval and a second time interval, and a comparison of an amount of light stored from captured light during at least a third time interval. The first, second, and third time intervals are different, but may overlap in some instances. In some embodiments, the amount of ambient light may be identified and subtracted from the inputs of the ratio. A switch may be used to prevent oversaturation of a storage element storing the stored energy.
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Citations
26 Claims
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1. A system comprising:
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a light emitter to emit light in pulses having a predetermined frequency; at least one light sensor to capture, using a plurality of storage elements, energy from the light that is emitted from the light emitter and reflected off of a surface over a period of time including at least four time intervals, the plurality of storage elements including; a first storage element to store energy from light captured during a first time interval that occurs for a length of time substantially equal to a duration of one of the pulses of light, a second storage element to store energy from light captured during a second time interval that occurs for a length of time substantially equal to an amount of time between each of the pulses, a third storage element to store energy from light captured during a third time interval that occurs during a portion of the first time interval, and a fourth storage element to store energy from light captured during a fourth time interval that occurs during a portion of the second time interval; and one or more processors to calculate a distance between the at least one light sensor and the surface, the distance being within a distance range defined by a distance traveled by the light during a cycle of the predetermined frequency, the one or more processors calculating the distance based at least in part on; a ratio of a measurement of the light stored during the first time interval and a measurement of the light stored during the second time interval, and a comparison of a measurement of the light stored during the third time interval and a measurement of the light stored during the fourth time interval. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method comprising:
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emitting, by at least one light emitter, light in pulses having a predetermined frequency; detecting, by at least one light sensor, the light after the light is reflected off a surface, the detecting being performed during at least three time intervals including; a first time interval that occurs for a length of time substantially equal to a duration of one of the pulses of light, a second time interval that occurs for a length of time substantially equal to an amount of time between each of the pulses, and a third time interval defined as occurring during a portion of the first time interval or during a portion of the second time interval, and calculating, by at least one processor, a distance associated with the surface, the distance being within a distance range defined by a distance traveled by light during a cycle of the predetermined frequency, the distance calculated based at least in part on; a ratio of a measurement of the light detected during the first time interval and a measurement of the light detected during the second time interval, and a comparison of a measurement of the light detected during the third time interval and a measurement of ambient light. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A system comprising:
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a light emitter to emit light in pulses having a predetermined frequency; at least one light sensor to detect the light that is emitted from the light emitter and reflected off a surface, the light sensor to detect the light that is emitted from the light emitter and reflected off of the surface during a period of time having at least n discrete time intervals of substantially equal length of time that occur during a cycle of the predetermined frequency, wherein n is an integer greater than or equal to three; and one or more processors to calculate a distance between the at least one light sensor and the surface, the distance being within a distance range defined by a distance traveled by the light during the cycle of the predetermined frequency, the one or more processors calculating the distance based at least in part on; a ratio of a measurement of the light detected during a first group of the time intervals and a second group of the time intervals, and a determination of which one of the discrete time intervals has a lowest measurement of detected light. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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26. A method comprising:
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emitting, by at least one light emitter, light in pulses having a predetermined frequency; detecting, by at least one light sensor, the light after the light is reflected off a surface, the detecting being performed during at least n discrete time intervals of substantially equal length of time that occur during a cycle of the predetermined frequency, wherein n is an integer greater than or equal to three; and calculating, by at least one processor, a distance between the at least one light sensor and the surface, the distance being within a distance range defined by a distance traveled by the light during the cycle of the predetermined frequency, the one or more processors calculating the distance based at least in part on; a ratio of a measurement of the light detected during a first group of the time intervals and a second group of the time intervals, and a determination of which one of the discrete time intervals has a lowest measurement of detected light.
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Specification