EP-4737943-A1 - POLARIZATION-BASED CROSSTALK MITIGATION IN OPTICAL RANGING SENSORS

EP4737943A1EP 4737943 A1EP4737943 A1EP 4737943A1EP-4737943-A1

Abstract

An example optical ranging sensor, a method for determining a proximity of a target at an optical ranging sensor, and a mobile electronic device comprising an optical ranging sensor are provided. The example optical ranging sensor includes an optical transmitter, an optical receiver, and a controller. The optical transmitter configured to generate a first signal having a first polarization state and a second signal having a second polarization state. The optical receiver configured to generate a first feedback signal resulting from one or more reflections of the first signal, and a second feedback signal resulting from one or more reflections of the second signal. The controller configured to generate a target feedback signal based on a comparison of the first feedback signal and the second feedback signal and determine a proximity of a target based on the target feedback signal.

Inventors

MCLEOD, STUART
DOWNING, JAMES PETER DRUMMOND

Assignees

STMicroelectronics International N.V.

Dates

Publication Date: 20260506
Application Date: 20251027

Claims (15)

An optical ranging sensor comprising: an optical transmitter configured to generate at least one signal having a polarization state; an optical receiver configured to generate: at least one feedback signal resulting from one or more reflections of said signal having a polarization state; and a controller configured to: generate a target feedback signal based at least on said feedback signal; and determine a proximity of a target based on the target feedback signal.
A method for determining a proximity of a target at an optical ranging sensor, the method comprising: causing an optical transmitter to transmit at least one signal having a polarization state; receiving from an optical receiver at least one feedback signal resulting from one or more reflections of said signal having a polarization state; generating a target feedback signal based at least on said feedback signal; and determining the proximity of the target based on the target feedback signal.
A mobile electronic device comprising: a housing; a display screen attached to the housing, the display screen comprising: a first side configured to emit transmitted light via a plurality of display pixels into an external environment; and an optical ranging sensor according to claim 1 or adapted to implement the method of claim 2, disposed within the housing, opposite the first side of the display screen.
The sensor of claim 1, or the method of claim 2, or the device of claim 3, wherein: said one signal having a polarization state is a first signal having a first polarization state of a plurality of signals; the optical transmitter generates and/or transmits a second signal having a second polarization state.
The sensor of claim 1 or 4, or the method of claim 2 or 4, or the device of claim 3 or 4, wherein: said one feedback signal is a first feedback signal of a plurality of feedback signals; said target feedback signal is generated based on a comparison of the first feedback signal and the second feedback signal.
The sensor of claim 1, or the method of claim 2, or the device of claim 3, or the sensor, method or device of claim 4 and 5, wherein the target feedback signal corresponds to a portion of said one signal having a polarization state or said first signal having a first polarization state reflected off the target.
The sensor or device of claim 6 in its dependency on claims 4 and 5, wherein to generate the target feedback signal, the controller is further configured for, or the method of claim 6 in its dependency on claims 4 and 5, wherein generating the target feedback signal further comprises: generating a first histogram corresponding to the first feedback signal; generating a second histogram corresponding to the second feedback signal; and generating the target feedback signal based on a comparison of the first histogram and the second histogram.
The sensor of at least one of the former sensor claims in their dependency on claim 5, or the device of at least one of the former device claims in their dependency on claim 5, wherein to generate the target feedback signal, the controller is further configured for, or the method of at least one of the former method claims in their dependency on claim 5, wherein generating the target feedback signal further comprises: determining a crosstalk difference signal by performing a difference between the first feedback signal and the second feedback signal; and applying a crosstalk function to determine a total crosstalk signal, wherein the crosstalk function relates the crosstalk difference to the total crosstalk signal.
The sensor or method or device of claim 8, wherein the crosstalk function is determined during a calibration period.
The sensor of at least one of the former sensor claims, or the method of at least one of the former method claims, or the device of at least one of the former device claims, wherein the proximity of the target is based on a time-of-flight associated with the target feedback signal.
The sensor of at least one of the former sensor claims, or the method of at least one of the former method claims, or the device of at least one of the former device claims, in their dependency on claim 4, wherein the first polarization state is orthogonal to the second polarization state.
The sensor of at least one of the former sensor claims, or the method of at least one of the former method claims, or the device of at least one of the former device claims, in their dependency on claim 4, wherein the optical transmitter is configured to alternate between generating the first signal having the first polarization state and the second signal having the second polarization state.
The sensor or the method or the device of claim 12, wherein the optical transmitter alternates between generating the first signal having the first polarization state and the second signal having the second polarization state after each integration period.
The sensor or the method or the device of claim 13, wherein the optical transmitter is a vertical-cavity surface-emitting laser.
The sensor or the method or the device of claim 14, wherein the vertical-cavity surface-emitting laser is configured to generate the first signal having the first polarization state and the second signal having the second polarization state based on a polarization control signal transmitted by the controller.

Description

TECHNOLOGICAL FIELD Embodiments of the present disclosure relate generally to optical ranging sensors, and more particularly, to mitigating inconsistencies due to crosstalk at an optical ranging sensor. BACKGROUND Optical ranging sensors may include an optical transmitter and an optical receiver. During operation, the optical ranging sensor transmits light toward a target object through one or more optically transmissive components, such as a coverglass. The transmitted light reflects off the target object and is received by the light receiver on the optical ranging sensor. The received light is used to extract useful information like the distance of the target object, the motion of the target object, the speed of the target object, surface properties of the target object, and so on. Light received at the optical receiver from unwanted sources, such as crosstalk light reflecting off a coverglass, may adversely affect the accuracy of an optical ranging sensor. Applicant has identified many technical challenges and difficulties associated with mitigating crosstalk at an optical ranging sensor. Through applied effort, ingenuity, and innovation, Applicant has solved problems related to crosstalk at an optical ranging sensor by developing solutions embodied in the present disclosure, which are described in detail below. BRIEF SUMMARY Various embodiments are directed to an example optical ranging sensor, a method for determining a proximity of a target at an optical ranging sensor, and a mobile electronic device comprising an optical ranging sensor. An embodiment provides an optical ranging sensor comprising: an optical transmitter configured to generate at least one signal having a polarization state;an optical receiver configured to generate: at least one feedback signal resulting from one or more reflections of said signal having a polarization state; anda controller configured to: generate a target feedback signal based at least on said feedback signal; anddetermine a proximity of a target based on the target feedback signal. An embodiment provides a method for determining a proximity of a target at an optical ranging sensor, the method comprising: causing an optical transmitter to transmit at least one signal having a polarization state;receiving from an optical receiver at least one feedback signal resulting from one or more reflections of said signal having a polarization state;generating a target feedback signal based at least on said feedback signal; anddetermining the proximity of the target based on the target feedback signal. An embodiment provides a mobile electronic device comprising: a housing;a display screen attached to the housing, the display screen comprising: a first side configured to emit transmitted light via a plurality of display pixels into an external environment; andan optical ranging sensor according to claim 1, disposed within the housing, opposite the first side of the display screen. In some embodiments: said one signal having a polarization state is a first signal having a first polarization state of a plurality of signals; andthe optical transmitter generates and/or transmits a second signal having a second polarization state. In some embodiments: said one feedback signal is a first feedback signal of a plurality of feedback signals; andsaid target feedback signal is generated based on a comparison of the first feedback signal and the second feedback signal. An example optical ranging sensor is provided. The example optical ranging sensor includes an optical transmitter, an optical receiver, and a controller. The optical transmitter configured to generate a first signal having a first polarization state and a second signal having a second polarization state. The optical receiver configured to generate a first feedback signal resulting from one or more reflections of the first signal, and a second feedback signal resulting from one or more reflections of the second signal. The controller configured to generate a target feedback signal based on a comparison of the first feedback signal and the second feedback signal; and determine a proximity of a target based on the target feedback signal. In some embodiments, the target feedback signal corresponds to a portion of the first signal reflected off the target. In some embodiments, to generate the target feedback signal, the controller is further configured to: generate a first histogram corresponding to the first feedback signal; generate a second histogram corresponding to the second feedback signal; and generate the target feedback signal based on a comparison of the first histogram and the second histogram. In some embodiments, to generate the target feedback signal, the controller is further configured to: determine a crosstalk difference signal by performing a difference between the first feedback signal and the second feedback signal; and apply a crosstalk function to determine a total crosstalk signal, wherein the crosstalk fu