TECHNICAL FIELD

This disclosure relates to systems and methods projecting light, and selectively controlling the projection of such light using a switchable diffuser arrangement.

BACKGROUND

Light projecting technologies are essential for enabling several important device functionalities. For example, structured light projecting is deployed in 3D camera modules of mobile phones for recognizing facial features. The projected light reflects off the facial features can be captured by a detector and analyzed by algorithms to “perceive” the topology of the face. Accordingly, authentication, emoji generation, image capture orientation, and other various functionalities can be designed based on inputs of the facial feature recognition.

Current light projecting technologies are disadvantaged for high cost, large size, and low integration. In particular, conventional light projecting technologies do not fully utilize already available light sources to achieve the multiple functions sought, and instead utilize multiple projection means to achieve their objectives. These inefficiencies impose bottlenecks for the advancement of device structure and function built on or around the light projection features. Therefore, improvements over the existing light projecting technologies are desirable for both the consumer market and the industry.

Light projection is a key step for various applications such as 3D feature detection and 3D mapping. In conventional systems, multiple light sources and light projection subsystems are deployed in combination with one another to provide 3D feature detection and 3D mapping technology. For instance, many conventional systems mount both a distinct flood light illumination component and a distinct dot projector component to achieve the desired readings. In general, the light produced by the flood light component is broad beam light that spreads substantially as it propagates. Flood light is used to illuminate a surface of interest for image capture. The light produced by dot projector, on the other hand, is narrow beam light configured with substantially parallel rays that do not disperse or diverge with propagation as readily as flood light. Using two distinct light sources to achieve both flood light illumination and dot projection is inefficient and results in cumbersome modules that are ill suited for small environments.

SUMMARY

Various embodiments of the present disclosure include light projecting systems and structures, switchable diffusers and other devices.

According to one aspect, a light projecting system comprises: a light projecting system configured to project a plurality of collimated beams of light; a switchable diffuser having a first surface and a second surface, the switchable diffuser coupled to a control source and configured to change from a first state to a second state responsive to the control source being changed from a first condition to a second condition; wherein in the first state the switchable diffuser is configured to receive at least a portion of the plurality of collimated beams of light at the first surface and project a flood light out of the second surface; wherein in the second state the switchable diffuser is configured to permit at least a portion of the plurality of collimated beams of light to propagate out of the second surface as an array; and a processing engine electrically coupled with a non-transitory computer readable medium having machine readable instructions stored thereon, which, when executed by the processing engine, cause the system to: oscillate the control source between the first condition and the second condition in accordance with a first predetermined pattern. It will be understood that, for purposes of this disclosure, the term “computer readable medium” extends to any medium configured to store machine readable instructions that can be executed by a processing engine. For example, such mediums may be found in a microcontroller unit, as system on a chip, or in any combination of the foregoing.

In some embodiments, the light projecting system comprises a vertical-cavity surface-emitting laser (VCSEL) element, a diffraction optics element, and/or a waveguide.

In some embodiments, the light projecting system comprises a waveguide, the waveguide comprising a surface A and a surface B; the surface A comprises a plurality of grating structures; the waveguide is configured to guide an in-coupled light beam to undergo total internal reflection between the surface A and the surface B; and the grating structures are configured to disrupt the total internal reflection to cause at least a portion of the in-coupled light beam to couple out of the waveguide from the surface A, the portion of the in-coupled light beam coupled out of the waveguide forming out-coupled light beams comprising the plurality of collimated beams of light; the surface A is in an x-y plane comprising an x-direction and a y-direction perpendicular to each other; the in-coupled light beam propagates inside the waveguide substantially along the x-direction of the x-y plane; the out-coupled light beams propagate substantially along a z-direction normal to the x-y plane; the grating structure is each associated with a grating depth, a duty cycle, a period, and an orientation in the x-y plane with respect to the z-direction; the grating structures at different x-direction positions have at least one of different grating depths or different grating duty cycles; the grating structures at different x-direction positions have different periods; and the grating structures at different y-direction positions have different orientations.

In some embodiments, the light projecting system comprises a plurality of diodes.

In some embodiments, the system further comprises: a detector configured to capture light information based on one or more flood light reflections off of an object, and array reflections off of an object, wherein: the machine readable instructions, when executed by the processing engine, cause the system to demultiplex light information received at the detector.

In some embodiments, the switchable diffuser comprises a polymer-liquid crystal mixture having a molecular orientation responsive to an applied voltage.

In some embodiments, the switchable diffuser comprises a meta-stable liquid crystal having a molecular orientation responsive to voltage.

In some embodiments, the switchable diffuser comprises a polymer dispersed liquid crystal.

In some embodiments, the switchable diffuser comprises a polymer network liquid crystal.

In some embodiments, the first predetermined pattern causes the light projecting out of the second surface of the switchable diffuser to comprise alternating bursts of flood light and collimated beams of light achieving a time division multiplexed emission.

In some embodiments, the first voltage condition is an applied voltage of 0V, and the second voltage condition is an applied voltage of between 1 V and 50 V or more.

In some embodiments, the first voltage condition is achieved upon application of a voltage of between 75-85V for a first period of time, and the second voltage condition is achieved upon application of a voltage of between 55-65V.

In some embodiments, the first predetermined pattern comprises switching between the first voltage condition and the second voltage condition two or more times during image capture period to achieve a predetermined ratio of flood light projection to collimated light projection.

In some embodiments, the predetermined oscillation pattern is configured to achieve a predetermined projection ratio of flood light to collimated light.

In some embodiments, the predetermined oscillation pattern is configured to achieve a predetermined projection ratio of flood light to collimated light, and the projection ratio is 1:1.

In some embodiments, the predetermined oscillation pattern is configured to achieve a predetermined projection ratio of flood light to collimated light, and the projection ratio is 10:1.

In some embodiments, the predetermined oscillation pattern is configured to achieve a predetermined projection ratio of flood light projection time to collimated light projection time, and the projection ratio is about between 1:1 to 10:1.

In some embodiments, the non-transitory computer readable medium is further configured with machine readable instructions stored thereon, which, when executed by the processing engine, cause the system to: oscillate the control source between the first condition and the second condition in accordance with a second predetermined pattern; and the second predetermined pattern comprises switching between the first voltage condition and the second voltage condition two or more times during a first image capture period to achieve a second predetermined ratio of flood light projection to collimated light projection, and further wherein the second predetermined ratio is different than the first predetermined ratio.

In some embodiments, the non-transitory computer readable medium is further configured with machine readable instructions stored thereon, which, when executed by the processing engine, cause the system to: adjust the time period of one or more of the first image capture period and the second image capture period based on one or more of a detected ambient lighting condition and a transaction security condition.

According to another aspect, a light projecting method comprises: projecting a plurality of collimated beams of light; providing a switchable diffuser having a first surface and a second surface, the switchable diffuser coupled to a control source and configured to change from a first state to a second state responsive to the control source being changed from a first condition to a second condition; wherein in the first state the switchable diffuser is configured to receive at least a portion of the plurality of collimated beams of light at the first surface, and project a flood light out of the second surface; wherein in the second state the switchable diffuser is configured to permit at least a portion of collimated beams of light to propagate out of the second surface as an array; oscillating the control source between the first condition and the second condition in accordance with a first predetermined pattern.

In some embodiments, projecting the plurality of collimated beams of light comprises projecting the plurality of collimated beams of light from a waveguide, the waveguide comprising a surface A and a surface B; the surface A comprises a plurality of grating structures; the waveguide is configured to guide an in-coupled light beam to undergo total internal reflection between the surface A and the surface B; and the grating structures are configured to disrupt the total internal reflection to cause at least a portion of the in-coupled light beam to couple out of the waveguide from the surface A, the portion of the in-coupled light beam coupled out of the waveguide forming out-coupled light beams comprising the plurality of collimated beams of light.

According to another aspect, a system in accordance with the present disclosure includes: a light source configured to generate light (e.g., IR light); a projecting structure configured to receive the generated light and responsively project a plurality of collimated beams of light (collectively referred to herein as a light projecting structure); and a switchable diffuser having a first surface and a second surface. In some embodiments, the switchable diffuser is coupled to a control source such as a voltage source. Though other control sources may be implemented with the present technology (e.g., current sources, etc.), the present disclosure regularly refers to a voltage sources by way of example only, and are not intended to be limiting. The switchable diffuser is configured to change from a first state to a second state responsive to the voltage source being changed from a first voltage condition (e.g., 0V) to a second voltage condition (e.g., 1-50V). When the switchable diffuser is in the first state, the switchable diffuser is configured to receive the plurality of columnated beams of light at the first surface, diffuse the plurality of collimated beams of light and project a flood light out of the second surface. When the switchable diffuser is in the second state, the switchable diffuser is configured to be substantially transparent to the plurality of collimated beams of light incident upon it, and to permit the plurality of collimated beams of light to propagate out of the second surface as an array (e.g., a dot array). Example systems may also include a detector configured to capture light information based on one or more flood light reflections off of an object, and dot array reflections off of an object. In some embodiments, the system is configured to demultiplex light information received at the detector.

In some embodiments, an example system of the present disclosure is provided with a controller to manipulate and regulate operations of elements of the system. The controller may include a processing engine electrically coupled with a non-transitory computer readable medium having machine readable instructions stored thereon, which, when executed by the processing engine, cause the system to perform various operations. For example, in some instances the instructions, when executed, cause the system to oscillate the voltage source between the first voltage condition and the second voltage condition in accordance with a predetermined oscillation pattern. In some embodiments, the predetermined oscillation pattern causes the light projecting out of the second surface of the switchable diffuser to comprise alternating bursts of flood light and collimated beams of light achieving a time division multiplexed emission. In some embodiments, the predetermined oscillation pattern comprises switching between the first voltage condition and the second voltage condition two or more times during image capture period to achieve a predetermined ratio of flood light projection to collimated light projection (e.g., from anywhere between 1:1-10:1, 1:1-100:1, 1:10-1:1, or 1:100-1:1, etc.).

In some embodiments, the systems of the present disclosure may include a module equipped with both a structured light detector (i.e., a non-ToF detector, e.g., an IR dot array detector) as well as a Time-of-Flight (“ToF”) detector. Both of the structured light detector and the ToF detector may be configured to receive light reflections from the light pulses projected from light projection system, but each may capture, transduce, filter, and/or assess the light differently (or produce signals that may be filtered and/or assessed differently) to derive feature, structure and/or depth information about objects upon which the light projected from light projecting system is incident.

In some embodiments, a light projecting subsystem of a system including both a structured light detector and a ToF detector may nevertheless include a single light source and single switchable diffuser. Such light source and switchable diffuser may operate in accordance with one or more features of such elements as discussed herein. In some embodiments, systems of the present disclosure may include a controller coupled with the structured light detector and the ToF detector, and configured to operate only one of the structured light detector and the ToF detector during a given image capture period—e.g., in “ToF mode” or “non-ToF mode” (ToF mode referring to the situation where only a ToF detector is operating during a given image capture period, and “non-ToF mode” referring to the situation where only a structured light detector is operating during a given image capture period. In other embodiments, such a controller may be configured to operate both the structured light detector and the ToF detector together during a given image capture period—e.g., in “hybrid mode” (hybrid mode referring to the case where controller synchronizes operations of the structured light detector and the ToF detector (along with the operation of other elements of the system, e.g., the timing of the switchable diffuser's change of state, the timing of the light sources emissions within the light projecting subsystem of the system, etc.) such that both detectors may coherently operate during a given image capture period.

In some embodiments employing ToF detectors, controller may switch between modes—e.g., switch between operation of the system in ToF mode, non-ToF mode, or hybrid mode—based on input from a user (e.g., user selection), or based upon one or more detected condition(s) (e.g., lighting conditions, component status detection, etc.).

In some embodiments, the technology of the present disclosure may include a system, comprising: an IR detector configured to capture light information based on one or more flood light reflections off of an object, and structured light array reflections off of an object; a Time-of-Flight (ToF) detector configured to measure time differences between the returning light reflections off of a surface of the object (or off of multiple surfaces of different objects), and to enable the determination of one or more depth measures associated with different portions of such surface(s) based on the time differences between different portions of returning light reflections; and a switchable diffuser having a first surface and a second surface, the switchable diffuser coupled to a control source and configured to change from a first state to a second state responsive to the control source being changed from a first condition to a second condition. In some such embodiments the first state the switchable diffuser may be configured to receive at least a portion of the plurality of collimated beams of light at the first surface and project a flood light out of the second surface. In second state the switchable diffuser may be configured to permit at least a portion of the plurality of collimated beams of light to propagate out of the second surface as an array. In some embodiments, the light projecting system includes a processing engine electrically coupled with a non-transitory computer readable medium having machine readable instructions stored thereon, which, when executed by the processing engine, cause the system to: oscillate the control source between the first condition and the second condition in accordance with a first predetermined pattern. In some embodiments, oscillating the control source between the first condition and the second condition in accordance with a first predetermined pattern causes a plurality of pulses of collimated light to be projected out of the switchable diffuser during a single image capture period. In some embodiments, the ToF sensor and the structured light sensor are configured to receive reflections of collimated light from one or more of the same pulses of collimated light during a single image capture period.

In some embodiments, the switchable diffuser may be controlled to emit pulses of collimated beams of light that effectuate a modulation of the collimated beams of light that the ToF detector may be configured to resolve. Such modulation may be one or more of pulsed amplitude modulation, pulsed frequency modulation, continuous wave amplitude modulation, and continuous wave frequency modulation.

In some embodiments, the technology provided herein is drawn to methods for performing the functionality described with respect to the example systems hereof.

According to another aspect, a light projecting system comprises: an IR detector configured to capture light information based on one or more flood light reflections off of an object, and array reflections off of an object; a Time-of-Flight (ToF) detector configured to detect differences between particles based on their time of flight; a switchable diffuser having a first surface and a second surface, the switchable diffuser coupled to a control source and configured to change from a first state to a second state responsive to the control source being changed from a first condition to a second condition; wherein in the first state the switchable diffuser is configured to receive at least a portion of the plurality of collimated beams of light at the first surface and project a flood light out of the second surface; wherein in the second state the switchable diffuser is configured to permit at least a portion of the plurality of collimated beams of light to propagate out of the second surface as an array; and a processing engine electrically coupled with a non-transitory computer readable medium having machine readable instructions stored thereon, which, when executed by the processing engine, cause the system to: oscillate the control source between the first condition and the second condition in accordance with a first predetermined pattern; cause the switchable diffuser to emit pulses of collimated beams of light to effectuate a modulation of the collimated beams of light that the ToF detector is configured to resolve.

According to another aspect, a light projecting method comprises: receiving light generated by a light source light and responsively projecting a plurality of collimated beams of light; providing a switchable diffuser having a first surface and a second surface, the switchable diffuser coupled to a voltage source and configured to change from a first state to a second state responsive to the voltage source being changed from a first condition to a second condition; and oscillating the voltage source between the first condition and the second condition in accordance with a first predetermined pattern, the voltage oscillations causing alternating flood light and dot array projections to be emitted from the second surface of the switchable diffuser in a time-division multiplexed manner.

In some embodiments, the method further comprises detecting, at a light sensor, light information from the alternating flood light and dot array light reflections off of an object, wherein the light sensor is synchronized with the voltage oscillations and/or the alternations in flood light and dot array light projection; demultiplexing light information detected at the light sensor; and generating a 3D map of the object based on the demultiplexed light information.

These and other features of the systems, methods, and non-transitory computer readable media disclosed herein, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for purposes of illustration and description only and are not intended as a definition of the limits of the invention.

