System and method for using a linear polarizer to reduce optical crosstalk for optical proximity sensors
First Claim
1. An optical proximity sensor, comprising:
- a light emitting device;
a photon detecting device;
a first polarization selection device and a second polarization selection device;
a transparent cover; and
an ink layer on the transparent cover,wherein the first polarization selection device is mounted between the photon detecting device and the ink layer,wherein the second polarization selection device is mounted between the light emitting device and the ink layer,wherein each of the first polarization selection device and the second polarization selection device is configured to block polarization originating from scattering induced by the ink layer on the transparent cover, andwherein each of the first polarization selection device and the second polarization selection device is configured to block s-polarized light and pass p-polarized light.
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Accused Products
Abstract
An optical proximity sensor often emits light, and detects the photons in the returned light signal. Because light can be reflected and scattered by cover glass and ink layer printed on the cover glass, optical crosstalk is a concern for the optical proximity sensors. In one embodiment, the present disclosure provides an optical proximity sensor including a linear polarizer to cover the photo detector, or a polarizer to cover the light emitting device, or two polarizers to cover both the photo detector and the light emitting device. The polarizer blocks the s-polarized light and only allows the p-polarized light to pass through. Because the scattered light is predominated by the s-polarization, the optical crosstalk may be reduced.
21 Citations
10 Claims
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1. An optical proximity sensor, comprising:
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a light emitting device; a photon detecting device; a first polarization selection device and a second polarization selection device; a transparent cover; and an ink layer on the transparent cover, wherein the first polarization selection device is mounted between the photon detecting device and the ink layer, wherein the second polarization selection device is mounted between the light emitting device and the ink layer, wherein each of the first polarization selection device and the second polarization selection device is configured to block polarization originating from scattering induced by the ink layer on the transparent cover, and wherein each of the first polarization selection device and the second polarization selection device is configured to block s-polarized light and pass p-polarized light. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An optical proximity sensor, comprising:
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a light emitting device; a photon detecting device; a first polarization selection device and a second polarization selection device; a transparent cover; and an ink layer on the transparent cover, wherein the first polarization selection device is mounted between the photon detecting device and the ink layer, wherein the second polarization selection device is mounted between the light emitting device and the ink layer, wherein a distance between the light emitting device and the photon detecting device and a distance between the light emitting device and the transparent cover are adjusted such that an edge of a beam of light emitted from the light emitting device incidents upon the transparent cover at an angle close to the Brewster angle, wherein each of the first polarization selection device and the second polarization selection device is configured to block polarization originating from scattering induced by the ink layer on the transparent cover, and wherein each of the first polarization selection device and the second polarization selection device is configured to block s-polarized light and pass p-polarized light.
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Specification