Distance sensing by IQ domain differentiation of time of flight (TOF) measurements
First Claim
1. A method for use with a system that includes an optical sensor and that is configured to determine at least one of a distance or presence of one or more moving objects relative to the optical sensor, the method comprising:
- (a) driving a light emitting element with a drive signal to thereby cause a light signal to be emitted;
(b) producing a sensor signal that is indicative of a portion of the light signal that reflects from one or more objects and is incident on the optical sensor;
(c) performing quadrature demodulation of the sensor signal to produce in-phase (I) and quadrature phase (Q) signals;
(d) determining derivatives of the in-phase (I) and quadrature-phase (Q) signals; and
(e) determining a phase of the derivatives of the in-phase (I) and quadrature-phase (Q) signals.
2 Assignments
0 Petitions
Accused Products
Abstract
A system and method for identifying a position of a moving object, regardless of static objects present in the optical field of an active infrared (IR) proximity detector, is provided. Moreover, a modulated light emitting diode (LED) signal is captured and processed through I/Q demodulation. Specifically, the reflections received at an IR sensor are demodulated to generate in-phase (I) and quadrature phase (Q) signals and the derivative of I/Q signals is obtained to isolate motion. For example, an I/Q domain differentiator or a high pass filter is employed to calculate the derivative, which actively remove the effects of all forms of static interference. Further, the phase of the derivative I/Q signals is determined and is utilized to reconstruct the distance at which the motion occurred.
-
Citations
23 Claims
-
1. A method for use with a system that includes an optical sensor and that is configured to determine at least one of a distance or presence of one or more moving objects relative to the optical sensor, the method comprising:
-
(a) driving a light emitting element with a drive signal to thereby cause a light signal to be emitted; (b) producing a sensor signal that is indicative of a portion of the light signal that reflects from one or more objects and is incident on the optical sensor; (c) performing quadrature demodulation of the sensor signal to produce in-phase (I) and quadrature phase (Q) signals; (d) determining derivatives of the in-phase (I) and quadrature-phase (Q) signals; and (e) determining a phase of the derivatives of the in-phase (I) and quadrature-phase (Q) signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A system, comprising:
-
a driver configured to produce a drive signal that drives a light emitting element to thereby cause a light signal to be emitted; an optical sensor configured to produce a sensor signal that is indicative of a portion of the light signal that reflects from one or more objects and is incident on the optical sensor; a demodulator configured to perform quadrature demodulation of the sensor signal to produce in-phase (I) and quadrature phase (Q) signals; a differentiator configured to determine derivatives of the in-phase (I) and quadrature phase (Q) signals; and a phase detector configured to determine a phase of the derivatives of the in-phase (I) and quadrature phase (Q) signals. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
-
-
21. A subsystem for use with a system that includes
a driver configured to produce a drive signal that drives a light emitting element to thereby cause a light signal to be emitted; - and
an optical sensor configured to produce a sensor signal that is indicative of a portion of the light signal that reflects from one or more objects and is incident on the optical sensor; wherein the subsystem comprises; a demodulator configured to perform quadrature demodulation of the sensor signal to produce in-phase (I) and quadrature phase (Q) signals; a differentiator configured to determine derivatives of the in-phase (I) and quadrature phase (Q) signals; and a phase detector configured to determine a phase of the derivatives of the in-phase (I) and quadrature phase (Q) signals; wherein when there are one or more moving objects and one or more static objects within a sensor field of the optical sensor, the in-phase (I) and quadrature-phase (Q) signals produced by the demodulator are indicative of both reflections from the one or more moving object and reflections from the one or more static objects within the sensor field of the optical sensor, and the derivatives of the in-phase (I) and quadrature-phase (Q) signals determined by the differentiator are indicative of reflections from one or more moving objects and are generally not indicative of reflections from one or more static objects within the sensor field of the optical sensor. - View Dependent Claims (22, 23)
- and
Specification