CN-121995386-A - Polarization-based crosstalk suppression in optical ranging sensors

Abstract

The present disclosure relates to polarization-based crosstalk suppression in optical ranging sensors. An example optical ranging sensor, a method for determining proximity of an object at an optical ranging sensor, and a mobile electronic device including an optical ranging sensor are provided. An example optical ranging sensor includes an optical transmitter, an optical receiver, and a controller. The optical transmitter is configured to generate a first signal having a first polarization state and a second signal having a second polarization state. The optical receiver is 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 is configured to generate a target feedback signal based on a comparison of the first feedback signal and the second feedback signal, and to determine a proximity of the target based on the target feedback signal.

Inventors

• S. McLeod
• J. P.D. Tao Ning

Assignees

• 意法半导体国际公司

Dates

Publication Date

20260508

Application Date

20251103

Priority Date

20241105

Claims (20)

1. 1. An optical ranging sensor, comprising: An optical transmitter configured to generate a first signal having a first polarization state and a second signal having a second polarization state; an optical receiver configured to: Generating a first feedback signal resulting from one or more reflections of said first signal, and Generating a second feedback signal resulting from one or more reflections of said second signal, and A controller configured to: Generating a target feedback signal based on a comparison of the first feedback signal and the second feedback signal, and A proximity of the target is determined based on the target feedback signal.
2. 2. The optical ranging sensor of claim 1 wherein the target feedback signal corresponds to a portion of the first signal reflected from the target.
3. 3. The optical ranging sensor of claim 2, wherein to generate the target feedback signal, the controller is further configured to: Generating a first histogram corresponding to the first feedback signal; generating a second histogram corresponding to the second feedback signal, and The target feedback signal is generated based on a comparison of the first histogram and the second histogram.
4. 4. The optical ranging sensor of claim 1, wherein to generate the target feedback signal, the controller is further configured to: Determining a crosstalk difference signal by performing a difference between the first feedback signal and the second feedback signal, and A crosstalk function is applied to determine a total crosstalk signal, wherein the crosstalk function correlates the crosstalk difference with the total crosstalk signal.
5. 5. The optical ranging sensor of claim 4, wherein the crosstalk function is determined during a calibration period.
6. 6. The optical ranging sensor of claim 1, wherein the proximity of the target is based on a time of flight associated with the target feedback signal.
7. 7. The optical ranging sensor of claim 1, wherein the first polarization state is orthogonal to the second polarization state.
8. 8. The optical ranging sensor of claim 1, wherein the optical transmitter is configured to alternate between generating the first signal having the first polarization state and generating the second signal having the second polarization state.
9. 9. The optical ranging sensor of claim 8 wherein after each integration period the optical transmitter alternates between generating the first signal having the first polarization state and generating the second signal having the second polarization state.
10. 10. The optical ranging sensor of claim 9 wherein the optical emitter is a vertical cavity surface emitting laser.
11. 11. The optical ranging sensor of claim 10, 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 emitted by the controller.
12. 12. A method for determining proximity of an object at an optical ranging sensor, the method comprising: causing the optical transmitter to transmit a first signal having a first polarization state; Receiving a first feedback signal from an optical receiver resulting from one or more reflections of the first signal; causing the optical transmitter to transmit a second signal having a second polarization state; receiving a second feedback signal from the optical receiver resulting from one or more reflections of the second signal; Generating a target feedback signal based on a comparison of the first feedback signal and the second feedback signal, and The proximity of the target is determined based on the target feedback signal.
13. 13. The method of claim 12, wherein the target feedback signal corresponds to a portion of the first signal reflected from the target.
14. 14. The method of claim 13, 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 The target feedback signal is generated based on a comparison of the first histogram and the second histogram.
15. 15. The method of claim 12, 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 A crosstalk function is applied to determine a total crosstalk signal, wherein the crosstalk function correlates the crosstalk difference with the total crosstalk signal.
16. 16. The method of claim 12, wherein determining the proximity of the target further comprises: a time of flight associated with the target feedback signal is determined.
17. 17. The method of claim 12, wherein the first polarization state is orthogonal to the second polarization state.
18. 18. The method of claim 12, further comprising: The optical transmitter is alternated between generating the first signal having the first polarization state and generating the second signal having the second polarization state.
19. 19. The method of claim 18, wherein after each integration period, the optical emitter alternates between generating the first signal having the first polarization state and generating the second signal having the second polarization state.
20. 20. A mobile electronic device, comprising: A housing; A display screen attached to the housing, the display screen comprising: a first face configured to emit emitted light into an external environment via a plurality of display pixels, and An optical ranging sensor disposed within the housing opposite the first face of the display screen, the optical ranging sensor comprising: An optical transmitter configured to generate a first signal having a first polarization state and a second signal having a second polarization state; An optical receiver configured to receive: 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 said second signal, and A controller configured to: Generating a target feedback signal based on a comparison of the first feedback signal and the second feedback signal, and A proximity of the target is determined based on the target feedback signal.

Description

Polarization-based crosstalk suppression in optical ranging sensors Technical Field Embodiments of the present disclosure relate generally to optical ranging sensors, and more particularly, to mitigating inconsistencies due to crosstalk at optical ranging sensors. Background The optical ranging sensor may include an optical transmitter and an optical receiver. During operation, the optical ranging sensor emits light toward a target object through one or more optically transmissive components, such as a cover slip (coverglass). The emitted light is reflected by the target object and received by an optical receiver on the optical ranging sensor. The received light is used to extract useful information such as the distance of the target object, the movement of the target object, the speed of the target object, the surface properties of the target object, etc. Light received at the optical receiver from unwanted sources (such as cross-talk light reflected from the cover slip) may adversely affect the accuracy of the optical ranging sensor. Applicant has determined a number of technical challenges and difficulties associated with mitigating crosstalk at optical ranging sensors. With the efforts, originality, and innovations applied, the applicant has addressed the problems associated with crosstalk at optical ranging sensors by developing solutions embodied in the present disclosure, which will be described in detail below. Disclosure of Invention Various embodiments relate to an example optical ranging sensor, a method for determining proximity of an object at an optical ranging sensor, and a mobile electronic device including an optical ranging sensor. An example optical ranging sensor is provided. An example optical ranging sensor includes an optical transmitter, an optical receiver, and a controller. The optical transmitter is configured to generate a first signal having a first polarization state and a second signal having a second polarization state. The optical receiver is 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 is 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 the target based on the target feedback signal. In some embodiments, the target feedback signal corresponds to a portion of the first signal reflected from 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 to apply a crosstalk function to determine the total crosstalk signal, wherein the crosstalk function correlates the crosstalk difference with the total crosstalk signal. In some embodiments, the crosstalk function is determined during a calibration period. In some embodiments, the proximity of the target is based on a time of flight associated with the target feedback signal. In some embodiments, the first polarization state is orthogonal to the second polarization state. In some embodiments, the optical transmitter is configured to alternate between generating a first signal having a first polarization state and generating a second signal having a second polarization state. In some embodiments, after each integration period, the optical emitter alternates between generating a first signal having a first polarization state and generating a second signal having a second polarization state. In some embodiments, the optical emitter is a vertical cavity surface emitting laser. In some embodiments, the vertical cavity surface emitting laser is configured to generate a first signal having a first polarization state and a second signal having a second polarization state based on a polarization control signal emitted by the controller. An example method for determining proximity of an object at an optical ranging sensor is also provided. The example method includes causing an optical transmitter to transmit a first signal having a first polarization state, receiving a first feedback signal resulting from one or more reflections of the first signal from an optical receiver, causing the optical transmitter to transmit a second signal having a second polarization state, receiving a second feedback signal resulting from one or more reflections of the second signal from the optical receiver, generating a target feedback signal based o