Patent Application
20240106192
The present disclosure generally relates to optical sensors having an array of dual function pixels operable to transmit and receive light, and electronic devices that include such pixel arrays. Such optical sensors may be used, for example, in conjunction with displays and cameras of such electronic devices.
Electronic devices, such as cell phones, digital cameras, tablet or laptop computers, and the like, often include optical sensors. Such optical sensors may emit light, such as laser light, or may receive incoming light from an environment exterior to the electronic device, or both. Optical sensors that are capable of both emitting and receiving light are sometimes referred to as active optical sensors.
Optical sensors may be part of an imaging system of the electronic device, or may be used in conjunction with a display panel of the electronic device, such as for range finding or other ambient light level detection, among other applications.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Disclosed herein are electronic devices that contain programmable active optical sensors. The programmable active optical sensors may include pixel arrays that include dual function light transmit and receive pixels, or hereinafter, ‘dual function pixels,’ or just ‘pixels’ if clear from the context. The pixels of such a pixel array are formed in a common set of epitaxial layers, and each pixel includes a respective vertical cavity surface-emitting laser (VCSEL) and a respective photodiode (PD). The electronic devices also include respective controllers electrically connected to each respective VCSEL and each respective PD. The controller is operable to apply a first electrical bias at a first time to configure a pixel as a light transmitter only, and to apply a second electrical bias at a second time to configure the pixel as a light receiver only.
The PDs of the pixels may be formed in a first subset of epitaxial layers of the common set of epitaxial layers, adjacent to a light input-output (LIO) layer of the programmable active optical sensor. The VCSEL diodes of the pixels may be formed in a second subset of epitaxial layers of the common set of epitaxial layers, opposite to the LIO layer of the programmable active optical sensor.
Also disclosed herein is an electronic device that includes a display component positioned adjacent to a light transmissive surface of the electronic device, an array of dual function pixels formed in a common set of epitaxial layers, and a controller. Each pixel of the array of dual function pixels includes a respective VCSEL diode and a respective PD. The array of pixels is positioned proximate to the display component, opposite to the light transmissive surface. The controller is operably linked to the respective VCSEL diode and the respective PD of each pixel of the array of pixels. When a first electrical bias is applied to a first pixel, the respective VCSEL diode of the first pixel is operable to emit light and the respective PD of the first pixel is unbiased. When a second electrical bias is applied to the first pixel, the respective PD of the first pixel is biased to detect light and the respective VCSEL diode of the first pixel is unbiased. The controller is operable to determine signal-to-noise ratios (SNRs) of at least some of the VCSEL diodes and at least some of the PDs, and configure different pixels to operate as VCSEL diodes or PDs at least partly in response to the determined SNRs.
The present disclosure also describes an electronic device that includes a camera, a controller, and an array of dual function pixels positioned adjacent to a light transmissive surface of the electronic device. The array of pixels is formed in a common set of epitaxial layers, with each pixel in the array of pixels including a respective VCSEL diode and a respective PD. The controller is electrically connected to each respective VCSEL diode and each respective PD of each pixel of the array of pixels, and is operable to apply a first electrical bias at a first time to configure the respective VCSEL diode of a first pixel to emit light, and to apply a second electrical bias at a second time to configure the respective PD of the first pixel to detect light. The controller may further be operable to associate a selected subset of pixels of the array of pixels with a section of a field of view of the camera.
The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements.
The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property for any element illustrated in the accompanying figures.
Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto.
Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims.
The embodiments described herein are directed to electronic devices having controllable or programmable optical sensors that include an array of pixels, of which at least some pixels may be structured both to emit light and receive light. Examples of such electronic devices include, but are not limited to, smart phones, laptop computers, security systems, digital cameras, and the like. In some embodiments, such optical sensors of the electronic devices may be part of imaging systems of the electronic devices. In some embodiments, such optical systems may be used in conjunction with a display of the electronic devices.
Such arrays of pixels of the electronic devices may include dual function light transmit and receive pixels, in which such pixels include both a photodiode (PD) and a vertical-cavity, surface emitting laser (VCSEL) diode. The PD and VCSEL diode of a pixel may be formed in a common set of epitaxial layers, with both the PD and VCSEL diode vertically stacked, one above the other, along the direction perpendicular to the plane of the common set of epitaxial layers. In this configuration, light emitted from the VCSEL diode is emitted (or ‘transmitted’) along the direction perpendicular to the plane of the common set of epitaxial layers to exit the array.
The common set of epitaxial layers for the PDs and VCSEL diodes, for some or all of the pixel of the array, may be initially formed in series, such as by deposition, across a substrate. Thereafter, regions may be formed, such as by etching, into the common set of epitaxial layers, through which electrical connections to the PD and VCSEL diode structures of pixels are formed, together with electrically insulating material to provide electrical separation of the pixels of the array.
Each pixel may have its functionality alterable or controllable by a controller or processor, which may be either integrated with a pixel array or located on a separate component of the electronic device. In one case, the PD structure within the pixel may be biased through the electrical connections so that the PD functions as a light detector. In another case, the VCSEL diode may be biased through the electrical connections to emit laser light, such as pulsed laser light.
The array of pixel may be attached or otherwise connected to a backplane, or to a separately formed chip, that includes electrical circuitry such as transistors, electrical vias or interconnects, processors or controllers, or other components electrically linked with the pixel of the array. These other components may provide the biases that select the function of each pixel of the array.
The pixels of an array may be individually programmed or biased to function either as a PD or as a VCSEL diode, and such functionality may be altered at different times. An array of pixels may at a first time be programmed or configured to have a majority of the pixels function as PDs, such as for optical sensing in a low light situation of an exterior environment of the electronic device. Alternatively, at a second time, the array of pixels may be reprogrammed or reconfigured to have a majority of the pixels function as VCSEL diodes, such as for depth sensing or range finding to objects exterior to the electronic device.
In one family of embodiments, electronic devices are described that have both an electronic display facing the device's exterior, and an array of pixels positioned behind the array (e.g., interior to the device). Controllers or processors of the electronic devices may select a subset of the pixels that have been determined to have their respective VCSEL diodes transmit their laser light through light transmissive openings between the light emitting components of the electronic display. The selected pixels may be used for depth sensing or range finding. Using only a subset of the pixels of the array may allow for reduced power consumption by the array.
In this family of embodiments, a controller may perform a selection process to redetermine which pixels of the array to use as light emitters. Such a selection process may be implemented, for example, periodically or when an impact to the device is detected.
In another family of embodiments, both one (or more) cameras and an array of pixels are configured adjacent to a light input/output surface of an electronic device. The pixels of the array may be dynamically correlated, or ‘registered,’ with areas of the field of view of the camera. In the case of a desired location in the camera's field of view for focusing, just the registered or corresponding pixels of the array may be used for depth sensing or range finding.
These and other embodiments are discussed below with reference to
Directional terminology, such as “top”, “bottom”, “upper”, “lower”, “front”, “back”, “over”, “under”, “above”, “vertical”, “horizontal”, “below”, “left”, “right”, etc. is used with reference to the orientation of some of the components in some of the figures described herein. Because components in various embodiments can be positioned in a number of different orientations, directional terminology is used for purposes of illustration and is not always limiting. Directional terminology is intended to be construed broadly, and therefore should not be interpreted to preclude components being oriented in different ways. Also, as used herein, the phrase “at least one of” preceding a series of items, with the term “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list. The phrase “at least one of” does not require selection of at least one of each item listed; rather, the phrase allows a meaning that includes at a minimum one of any of the items, and/or one of any combination of the items, and/or one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or one or more of each of A, B, and C. Similarly, it may be appreciated that an order of elements presented for a conjunctive or disjunctive list provided herein should not be construed as limiting the disclosure to only that order provided.
The display 104 may include one or more light-emitting elements, and in some cases may be a light-emitting diode (LED) display, an organic LED (OLED) display, a liquid crystal display (LCD), an electroluminescent (EL) display, thin film transistor (TFT) display, or another type of display. In some embodiments, the display 104 may include, or be associated with, one or more touch and/or force sensors that are configured to detect a touch and/or a force applied to a surface of the front cover 106. As described below, the display 104 may be used in conjunction with an array of pixels, such as an array of dual function light transmit and receive pixels.
The various components of the housing 102 may be formed from the same or different materials. For example, a sidewall 118 of the housing 102 may be formed using one or more metals (e.g., stainless steel), polymers (e.g., plastics), ceramics, or composites (e.g., carbon fiber). In some cases, the sidewall 118 may be a multi-segment sidewall including a set of antennas. The antennas may form structural components of the sidewall 118. The antennas may be structurally coupled (to one another or to other components) and electrically isolated (from each other or from other components) by one or more non-conductive segments of the sidewall 118. The front cover 106 may be formed, for example, using one or more of glass, a crystal (e.g., sapphire), or a transparent polymer (e.g., plastic) that enables a user to view the display 104 through the front cover 106. In some cases, a portion of the front cover 106 (e.g., a perimeter portion of the front cover 106) may be coated with an opaque ink to obscure components included within the housing 102. The back cover 108 may be formed using the same material(s) that are used to form the sidewall 118 or the front cover 106. In some cases, the back cover 108 may be part of a monolithic element that also forms the sidewall 118 (or in cases where the sidewall 118 is a multi-segment sidewall, those portions of the sidewall 118 that are conductive or non-conductive). In still other embodiments, all of the exterior components of the housing 102 may be formed from a transparent material, and components within the device 100 may or may not be obscured by an opaque ink or opaque structure within the housing 102.
The front cover 106 may be mounted to the sidewall 118 to cover an opening defined by the sidewall 118 (i.e., an opening into an interior volume, in which various electronic components of the device 100, including the display 104, may be positioned). The front cover 106 may be mounted to the sidewall 118 using fasteners, adhesives, seals, gaskets, or other components.
A display stack or device stack (hereafter referred to as a “stack”) including the display 104 may be attached (or abutted) to an interior surface of the front cover 106 and extend into the interior volume of the device 100. In some cases, the stack may include a touch sensor (e.g., a grid of capacitive, resistive, strain-based, ultrasonic, or other type of touch sensing elements), or other layers of optical, mechanical, electrical, or other types of components. In some cases, the touch sensor (or part of a touch sensor system) may be configured to detect a touch applied to an outer surface of the front cover 106 (e.g., to a display surface of the device 100). In some embodiments, the stack may include an array of dual function light transmit and receive pixels.
In some cases, a force sensor (or part of a force sensor system) may be positioned within the interior volume above, below, and/or to the side of the display 104 (and in some cases within the device stack). The force sensor (or force sensor system) may be triggered in response to the touch sensor detecting one or more touches on the front cover 106 (or a location or locations of one or more touches on the front cover 106), and may determine an amount of force associated with each touch, or an amount of force associated with a collection of touches as a whole. In some embodiments, the force sensor (or force sensor system) may be used to determine a location of a touch, or a location of a touch in combination with an amount of force of the touch. In these latter embodiments, the device 100 may not include a separate touch sensor.
As shown primarily in
The device 100 may also include buttons or other input devices positioned along the sidewall 118 and/or on a back surface of the device 100. For example, a volume button or multipurpose button 120 may be positioned along the sidewall 118, and in some cases may extend through an aperture in the sidewall 118. In other embodiments, the button 120 may take the form of a designated and possibly raised portion of the sidewall 118, but the button 120 may not extend through an aperture in the sidewall 118. The sidewall 118 may include one or more ports 122 that allow air, but not liquids, to flow into and out of the device 100. In some embodiments, one or more sensors may be positioned in or near the port(s) 122. For example, an ambient pressure sensor, ambient temperature sensor, internal/external differential pressure sensor, gas sensor, particulate matter concentration sensor, or air quality sensor may be positioned in or near a port 122.
In some embodiments, the back surface of the device 100 may include a rear-facing camera 124 that includes one or more image sensors (see
One or both of the rear-facing camera 124 and the second imaging sensor 126 may include one or more pixel arrays. The pixels of such pixel arrays may be dual function light transmit and receive pixels, as described herein.
The processor 204 may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions, whether such data or instructions is in the form of software or firmware or otherwise encoded. For example, the processor 204 may include a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a controller, or a combination of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitably configured computing element or elements. In some cases, the processor 204 may provide part or all of the processing system or processor described herein.
It should be noted that the components of the electronic device 200 can be controlled by multiple processors. For example, select components of the electronic device 200 (e.g., the sensor system 210) may be controlled by a first processor and other components of the electronic device 200 (e.g., the electronic display 202) may be controlled by a second processor, where the first and second processors may or may not be in communication with each other.
The power source 206 can be implemented with any device capable of providing energy to the electronic device 200. For example, the power source 206 may include one or more batteries or rechargeable batteries. Additionally or alternatively, the power source 206 may include a power connector or power cord that connects the electronic device 200 to another power source, such as a wall outlet.
The memory 208 may store electronic data that can be used by the electronic device 200. For example, the memory 208 may store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, instructions, and/or data structures or databases. The memory 208 may include any type of memory. By way of example only, the memory 208 may include random access memory, read-only memory, Flash memory, removable memory, other types of storage elements, or combinations of such memory types.
The electronic device 200 may also include one or more sensor systems 210 positioned almost anywhere on the electronic device 200. The sensor system(s) 210 may be configured to sense one or more types of parameters, such as but not limited to, vibration; light; touch; force; heat; movement; relative motion; biometric data (e.g., biological parameters) of a user; air quality; proximity; position; connectedness; surface quality; and so on. By way of example, the sensor system(s) 210 may include a heat sensor, a position sensor, a light or optical sensor, a self-mixing interferometry (SMI) sensor, an image sensor (e.g., one or more of the image sensors or cameras described herein), an accelerometer, a pressure transducer, a gyroscope, a magnetometer, a health monitoring sensor, an air quality sensor, and so on. Additionally, the one or more sensor systems 210 may utilize any suitable sensing technology, including, but not limited to, interferometric, magnetic, capacitive, ultrasonic, resistive, optical, acoustic, piezoelectric, or thermal technologies.
In particular, the sensor system(s) 210 of the electronic device 200 may include one or more cameras, or other types of image sensors or active optical sensors, that include pixel arrays as described herein, and which may be operated or controlled, such as by the processor 204, by the methods described herein in relation to
The I/O mechanism 212 may transmit or receive data from a user or another electronic device. The I/O mechanism 212 may include the electronic display 202, a touch sensing input surface, a crown, one or more buttons (e.g., a graphical user interface “home” button), one or more microphones or speakers, one or more ports such as a microphone port, and/or a keyboard. Additionally or alternatively, the I/O mechanism 212 may transmit electronic signals via a communications interface, such as a wireless, wired, and/or optical communications interface. Examples of wireless and wired communications interfaces include, but are not limited to, cellular and Wi-Fi communications interfaces.
The illumination projector 214 may be configured as described with reference to
The various pixels of the pixel array 300 may be able to switch functionality, or “configuration,” either to receive incoming light, or to emit, or “transmit” light. Certain embodiments of pixels with such reconfigurable functionality are described below, in which the pixels are formed with both a photodiode (PD) and a vertical-cavity, surface-emitting laser (VCSEL) diode in a common set of semiconductor epitaxial layers. The semiconductor epitaxial layers may be formed initially on a single substrate, with subsequent electrical isolation of the reconfigurable pixels by etching of the semiconductor epitaxial layers, deposition of insulating material, and other operations. Pixels with such reconfigurable functionality are herein termed dual function light transmit and receive pixels, or ‘dual function pixels’ or just ‘pixels’ when clear from contest. The functional reconfiguration of such pixels may be accomplished by applying different electrical biases to electrical contacts of the pixels, with such electrical biases implemented by a controller and/or processor. The electrical biases may include voltages from voltage sources on or exterior to the pixel array. The voltages may be applied to the electrical contacts through switching or control circuitry controlled by the controller or processor.
At another time T1, as shown in
The pixel 400 includes three electrical contacts 408a, 408b, and 408c. A first electrical bias may be applied at least at the electrical contacts 408a and 408b to configure the VCSEL diode formed in the first set of layers 402 to emit light. A second electrical bias may be applied at least at the electrical contacts 408b and 408c to configure the PD in the second set of layers 404 to receive light. For convenience of illustration, the electrical contacts 408a-c are shown as localized rectangles, but one skilled in the art will understand that the electrical contacts 408a-c may extend further around and/or between the respective layers on which they are illustrated.
The VCSEL diode formed in the first set of layers 402 may include one or more quantum wells in the quantum well layer 402b. The VCSEL diode in the layers 402 may include a first distributed Bragg reflector (DBR) 402a formed in multiple layers of a first doping type, and a second DBR 402c of a second doping type. Further details of the structure of the VCSEL diode in the second set of epitaxial layers 404 will be described in relation to
The PD in the second set of epitaxial layers 404 may have a p-n junction 404b formed at an interface between a first set of layers 404a of a first doping type and a second set of layers 404c of a second doping type. Further details of the structure of the PD in the second set of epitaxial layers 404 will be described in relation to
Next to the p++ type contact layer 504, are epitaxial layers from which a PD of a pixel is formed. These epitaxial layers include layers forming a first p-type distributed Bragg reflector (DBR) 506, a PD absorption layer 508, an optional multiplication layer 510, and layers for a first n-type DBR 512. Photodiodes so formed may be specific embodiments of the PD of the pixel 400 in the layers 404 of
The PD absorption layer 508 may be formed as one of: a single bulk layer, or multiple quantum wells of epitaxial material, such as InGaAs, InGaAsN, InGaAsP, or another material. If there is no multiplication layer 510, the PD formed by the first p-type DBR 506, the PD absorption layer 508, and the first n-type DBR 512 has the functionality of the resonant cavity photodiode. If there is an included multiplication layer 510, the PD formed by the first p-type DBR 506, the PD absorption layer 508, the multiplication layer 510, and the first n-type DBR 512 instead has the functionality of either a resonant cavity, avalanche photodiode (RC-APD), or a resonant cavity, single-photon avalanche diode (RC-SPAD).
An n-type intra-cavity contact layer 514 is positioned between the first n-type DBR 512 and a second n-type DBR 516. The n-type intra-cavity contact layer 514 may include or connect to an electrical bias source, such as a voltage source.
Opposite to the n-type intra-cavity contact layer 514 from the layers for a first n-type DBR 512 are the layers from which a VCSEL diode of a pixel is formed. These layers include the 4 layers forming a second n-type DBR 516, quantum well layers 518, an oxidation layer 520, and layers forming a second p-type DBR 522.
Beneath the second p-type DBR 522 is a second p++ type contact layer 524. The second p++ type contact layer 524 may have or connect to another electrical contact of an electrical bias source, such as a voltage source.
The epitaxial layers of the first and second p-type DBR 506 and 522, and the first and second n-type DBR 512 and 516, may include multiple pairs of layers, of alternating materials having different refractive indices, of the respective doping type, each pair of layers forming a Bragg pair. An exemplary pair of materials that may be used to form a distributed Bragg reflector 303b are aluminum arsenide and GaAs. The material for the first and second p-type DBR 506 and 522, and the first and second n-type DBR 512 and 516, may be one of: a purely epitaxial material such as AlGaAs, AlGaInP, or another such epitaxial material; a purely dielectric material; or a hybrid material.
The material of the quantum well layer 518 may similarly be one of: a purely epitaxial material such as AlGaAs, AlGaInP, or another such epitaxial material; a purely dielectric material; or a hybrid material. In the quantum well layer 518 there may be either one group of quantum wells, or multiple groups of quantum wells, so that the resulting VCSEL diode is, respectively, a single junction or a multi-junction VCSEL diode.
More specifically, on a substrate 532, a first n-type contact layer 534 is formed. On the first n-type contact layer 534 are epitaxial layers from which a PD of a pixel is formed: layers of a first n-type DBR 536, an optional multiplication layer 538, a PD absorption layer 540, and layers of a first p-type DBR 542.
Beneath the layers of the first p-type DBR 542 is a p++ type intracavity contact layer 544, at which an electrical contact may be positioned to connect to an electrical bias source.
Beneath the first p-type DBR 542 are layers from which a VCSEL diode of a pixel may be formed: a second p-type DBR 546, an oxidation layer 548, a quantum wells layer 550, and layers of a second n-type DBR 552.
Beneath the second n-type DBR 552 is a second n-type contact layer 554 at which an electrical contact may be positioned to connect to an electrical bias source.
The functionality and materials of the first and second n-type DBRs 536 and 552, and the first and second p-type DBRs 542 and 546 are as described for the first and second n-type DBRs 512 and 516, and the first and second p-type DBRs 506 and 522 of the configuration 500.
The functionality of the PD and VCSEL diode that are formed in the epitaxial layers of the configuration 530 are as described for the PD and VCSEL diode that are formed in the epitaxial layers of the configuration 500, except for changes, recognizable by one skilled in the art, due to the reversed doping types.
In the configuration 560, a first vertical ‘trench’ or gap G1568a is formed, such as by etching, from the second p++ contact layer 524 to the first p++ type contact layer 504. The trench G1568a extends around the epitaxial layers to form a first mesa structure that includes the first p-type DBR 506, the PD absorption layer 508, the optional multiplication layer 510, the first n-type DBR 512, and the n-type intra-cavity contact layer 514. The shape of the first mesa structure may, for example, have a rectangular box shape as shown in
A second vertical gap or ‘trench’ G2568b has been etched from the second p++ contact layer 524 up to the n-type intra-cavity contact layer 514. The second trench 568b also extends around the epitaxial layers to form a second, narrower mesa structure that includes the second n-type DBR 516, the quantum well layer(s) 518, the oxidation layer 520 and the second p-type DBR layers 522.
Electrical contacts 564a and 564b have been added to the n-type intra-cavity contact layer 514. The electrical contacts 564a and 564b may form a single connected contact by extending at least partially around the bottom surface of the n-type intra-cavity contact layer 514. An electrical connection 565 may extend from the electrical contact 564b to other components exterior to the pixels, such as to one or more voltage sources with voltages regulated or applied by a controller. An electrical bias may be applied to the PD structure with a first voltage applied at the electrical contacts 562a and/or 562b, and a second voltage applied at the electrical contacts 564a and/or 564b.
An electrical contact 566 has been added to the second p++ contact layer 524 on the side opposite to the second p-type DBR 522. An electrical connection 567 may extend from the electrical contact 566 to other components exterior to the pixels, such as to one or more voltage sources with voltages regulated or applied by a controller. An electrical bias may be applied to the VCSEL diode structure with a first voltage applied at the electrical contacts 564a and/or 564b, and a second voltage applied at the electrical contact 566.
An insulating or dielectric material, such as SiO2 may be formed, such as by deposition, in the trench G1568a and the trench G2568b after the electrical contacts 562a, 562b, 564a, 564b, and 566 have been added to provide electrical isolation between pixels. A further extension of the insulating material (not shown) may extend through the first p++ contact layer to the substrate 502 to provide electrical separation of the pixels.
When the pixel with the configuration 560 is to operate as a PD, it may be reversed biased by applying a negative voltage to the electrical contacts 562a and 562b, with a ground voltage at electrical contacts 564a and 564b. Also, a ground voltage may be applied to electrical contact 566 so that the VCSEL diode section of the pixel is unbiased. When the pixel is to operate as a light emitter, the electrical contacts 564a and 564b may have a ground voltage applied, while the electrical contact 566 has a positive voltage applied so that the VCSEL diode section is forward biased. Also, the electrical contacts 562a and 562b may also have a ground voltage applied so that the PD section is unbiased.
One skilled in the art will recognize that analogous formation of trenches and mesa structures, and addition of electrical contacts, connections, and insulating material may be applied to the configuration 530 of epitaxial layers shown in
For the pixel array 600, the substrate layer, such as substrate 502 of
The pixel 602a has a first electrical connection 604a that extends through the insulating material 610 and by the via 604b to a signal line in the backplane 612. The first electrical connection 604a may be configured as described for the electrical connection 563 of
In the configuration of the pixel array 600 shown, the pixels 602a and 602d are configured as PD light detectors, such as by the reverse bias voltages applied to their PD sections, as described in relation to
In the configuration of the pixel array 600 shown, the pixels 602b and 602c are configured as VCSEL diodes to emit laser light, such as by having forward bias voltages applied to their VCSEL diode sections as described in relation to
In some embodiments, an electronic device having a such a programmable pixel array of pixels, such as the pixel array 600, as an optical sensor may adjust the respective number of pixels operating as PDs and as VCSEL diodes. Such an adjustment may be based on a signal-to-noise ratio, such as may be determined in a light sensing operation. As an example, in a low light environment situation, with a first number of pixels operating as PDs, the amount of light induced photocurrent detected from the PDs may not sufficiently exceed a noise current level of PDs. In such a case, a controller may reconfigure more pixels as PDs to obtain better imaging of the scene. Alternatively, in a high light exterior environment, more pixels may need to be reconfigured to function as VCSEL diodes. A controller may reconfigure the pixels of the pixel array in response to a received adjustment signal. The adjustment signal may be a based on one or more criteria or tests applied by the controller itself, or by an external input, such as from a user or a separate processor of the electronic device that contains the pixel array. As examples, a user may determine that a greater exposure is needed, and so want to increase the number of pixels configured as light receivers. Or an impact detected by the electronic device may indicate a need for a recalibration procedure or another operation. Or the recalibration or other operation may be performed after a scheduled period of time has elapsed.
In another example, the pixel array 600 may be used for ranging or depth sensing, in which the pixels configured as VCSEL diodes emit pulsed laser light, whose reflections are detected by the pixel configured as PDs. If the measured photocurrent is too low, a controller may reconfigure more pixels to function as PDs.
The display device 702 includes a cover glass 704, a separating layer 706, a color light emitting diode (LED) layer 708 and a backplane layer 710. The color LED layer 708 may include color emitting LEDs 720a-c, 722a-c, and 724a-c, which may each be red (R), green (G), blue (B) triplets. The color emitting LEDs 720a-c, 722a-c, and 724a-c may be organic LEDs, and the color LED layer may include thin film transistors, and possibly other components, for operational control of the LEDs.
The pixel array 712 includes a pixel layer 714 and a backplane 716. The pixel layer 714 and the backplane 716 may be configured as described for the pixel array 600 of
In the situation shown in
The pixel 730d is positioned on the pixel array 712 so that its transmitted light 732 is predominantly directed toward a light transmissive gap 725 between the triple of LEDs 720a-c and the triple of LEDs 722a-c of the display device 702, and so a significant portion of the transmitted light 732 passes through the cover glass 704. Some of the transmitted light 732 may, however, be reflected from the backplane layer 710 and detected by the PDs of the selected set of neighboring pixels 730a-c and 730e-g. This is shown in the cross-sectional view 700 as the reflected light 733a and 733b received at pixels 730b and 730f. For clarity, other reflections received at other pixels of the selected set of neighboring pixels 730a-c and 730e-g are not shown.
The bar graph 718a plots respective measured values of the reflected light detected by the PDs in the selected set of neighboring pixels 730a-c and 730e-g. The measured values may be photocurrents in the PDs, voltages or voltage spikes (e.g., in the case of avalanche PDs), heat values induced in the PDs by the received reflected light 733a and 733b, or other measured values correlated with the amount of received reflected light 733a and 733b.
In the cross-sectional view 740 of
As a result, the PDs of the pixels to the left of the transmitting pixel 730e in the selected set, pixels 730b-d, detect a smaller amount of the reflected light 735a compared to the amount of reflected light 735b detected by the pixels to the right of the transmitting pixel 730e in the selected set, pixels 730f-h. The resulting asymmetry in amounts of detected reflected light is plotted in the bar graph 718b. A controller of the electronic device may determine that the pixel 730e is not optimal for use as a light transmitter in other operations, such as range finding, of the electronic device.
In the cross-sectional view 750 of
In the cross-sectional view 760 of
In the situation shown, the pixels 762a-d and 764a-d have been selected for light transmission based on a determination that an acceptable portion of their transmitted light 770 and 772 pass through the display device 702 into the exterior environment of the electronic device. The remaining pixels 761a-b, 763a-d, and 765a-b, may be either unused, or used for light detection. The controller may determine, such as by detection of ambient light conditions in the environment, that fewer of the pixels 762a-d and 764a-d are needed for light transmission operations of the electronic device.
The testing and selection process described in relation to
The camera may be an RGB (red, green, blue) camera, and the pixel array of pixels may be used to provide depth or range finding information about the object 801. The depth information may be used for autofocusing capabilities of the camera. The field of view 800 may include a region of interest (ROI) 804. The ROI 804 may be user-defined.
In some embodiments, the pixel array of pixels may be used in conjunction with the camera, such as for focusing of the camera on the ROI. In these embodiments, the pixel array of pixels may be correlated or registered with the pixel array of the camera. With such a registration of the pixel array of pixels to the camera's pixel array, once the ROI 804 has been selected within the camera's field of view 802, a controller may configure, as VCSEL diodes and to transmit light, just the pixels of the pixel array that are registered to the camera's pixels that contain the ROI 804. This may reduce power usage in the electronic device.
In some embodiments, the pixel array of pixels may be registered or correlated with a second camera of the electronic device, either in addition to, or in lieu of, registration to the first RGB camera.
The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.
