Display stacks with integrated ambient light sensors

Systems, methods, and computer-readable media are disclosed for ambient light sensing for electronic displays. In one embodiment, a device may include a light guide with a first surface and a second surface, where the light guide has a first refractive index value. The device may include a light sensor mounted on either the first surface or the second surface, the light sensor positioned such that at least a portion of ambient light incident upon the light guide is directed to a detection window of the light sensor, where the detection window has a second material having a second refractive index value. The device may include an adhesive layer configured to optically couple the light sensor to the light guide, the adhesive layer having a third refractive index value equal to or greater than the first refractive index value and equal to or less than the second refractive index value.

BACKGROUND

A variety of devices, such as electronic book (“e-Book”) reader devices, desktop computers, portable computers, smartphones, tablet computers, game consoles, televisions, and so forth are used to access various forms of content. Ambient light sensors may be used in some devices to gather information about ambient light levels. In order to detect ambient light, ambient light sensors may need to be positioned in a particular orientation. Positioning of ambient light sensors may therefore affect accuracy of measurements, manufacturing processes, aesthetic appearances, or other aspects of devices that include ambient light sensors.

The detailed description is set forth with reference to the accompanying drawings. The drawings are provided for purposes of illustration only and merely depict example embodiments of the disclosure. The drawings are provided to facilitate understanding of the disclosure and shall not be deemed to limit the breadth, scope, or applicability of the disclosure. The use of the same reference numerals indicates similar, but not necessarily the same or identical components. However, different reference numerals may be used to identify similar components as well. Various embodiments may utilize elements or components other than those illustrated in the drawings, and some elements and/or components may not be present in various embodiments. The use of singular terminology to describe a component or element may, depending on the context, encompass a plural number of such components or elements and vice versa.

DETAILED DESCRIPTION

Overview

This disclosure relates to, among other things, systems, methods, computer-readable media, techniques, and methodologies for detecting ambient light incident upon an electronic device, where a light sensor configured to detect ambient light is positioned on an optical stack or display stack and mounted using an optically clear adhesive. In example embodiments of the disclosure, the light sensor may be positioned and/or mounted such that the light sensor may detect ambient light via coupling to a light guide of the display stack. The light sensors of example display stacks (also referred to as optical stacks) described herein may not be in direct exposure to ambient light, but may detect or otherwise measure ambient light incident upon a device via coupling to the light guide of the display stacks in certain embodiments. Because the light sensor may not need to be directly exposed to ambient light, unpleasant aesthetic effects, such as black holes on faces of white devices, may be avoided or reduced. As a result, structural integrity may be improved due to, for example, a reduction in holes formed in the device. Measurement of ambient light may also be improved due to reduced accidental occlusion of the light sensor by a user, for example. Ambient light detections or measurements may be used by the device to perform certain functions, such as adjusting a display brightness. While example embodiments of the disclosure may be described as including ambient light sensors, the disclosure is more broadly applicable to any form of light sensor.

Example embodiments of the disclosure relate to systems, methods, computer-readable media, techniques, and methodologies for detecting ambient light incident upon or otherwise impinging upon a device, such as an e-reader or other mobile device, by coupling a light sensor to a light guide included in a display stack of the device. A light sensor in accordance with example embodiments of the disclosure may generate accurate ambient light measurements while being positioned entirely internal to a device or otherwise positioned such that the light sensor is not directly exposed to ambient light.

A variety of devices, such as electronic book (“e-Book”) reader devices, desktop computers, portable computers, smartphones, tablet computers, televisions, wearable devices, and so forth are used to access various forms of content and other information. Such devices may include displays that are used to present information or content to users. Such displays may be emissive, reflective, or a combination thereof. An emissive display emits light to form an image. Emissive displays include, but are not limited to, backlit liquid crystal displays, organic light emitting diode displays, plasma displays, cathode ray tubes, light-emitting diodes, image projectors, and so forth. Reflective displays use incident light to form an image. Incident light may be provided, for example, by the sun, general illumination in a room or environment, a reading light, a front light, and so forth. Reflective displays include, but are not limited to, electrophoretic displays, interferometric displays, electrowetting, cholesteric displays, and so forth.

Where an illumination source is used, such as in a backlit liquid crystal display (“LCD”) or a frontlit electrophoretic display (“EPD”), an intensity of the illumination may be varied based at least in part on the ambient light. For example, in sunlight, a backlight on an LCD may be increased while a frontlight on an EPD may be decreased in the same conditions. Light sensors, or ambient light sensors, may be used to provide information about the intensity of the ambient light which may be used by the device to determine whether certain functions are to be performed, such as varying a display illumination level.

Certain embodiments of the disclosure include display stacks with integrated ambient light sensors. Ambient light sensors may be coupled or otherwise mounted to a light guide panel or related component of the display stacks using an optically clear adhesive, such as a liquid optically clear adhesive. The display stack may include certain components, such as a cover glass, one or more touch layers, one or more adhesive layers, and other components.

Referring toFIG. 1, an example display stack100is partially depicted in exploded view in accordance with one or more embodiments of the disclosure. The display stack100may include a cover glass110, a touch layer120, a light guide panel130, a light sensor140coupled to the light guide panel130, and a display panel150. One or more of the layers of the display stack100may be joined together or otherwise coupled using one or more adhesives, such as an optically clear adhesive liquid or tape. Other embodiments may include additional or fewer components in a display stack or may have components in different positions. For example, other embodiments may not include the touch layer120, or may have additional material between the touch layer120and the light guide panel130, or other components.

The cover glass110may be formed from glass112and may form an outer or outermost layer of the display stack100. The cover glass110may have a uniform or constant thickness or a variable thickness. In some embodiments, the cover glass110may form a top most layer of not only the display stack100, but of the electronic device that includes the display stack100.

The touch layer120may include a resistive and/or capacitive touch sensor and may be formed from any suitable material configured to detect touch input, such as a capacitive layer, an indium tin oxide coating or layer, a conductive layer, or another material. Although a portion of a single touch layer120is illustrated, one or more touch layers or components associated with the touch layer120may be may be included in, positioned adjacent to, coplanar with, or in another position in the display stack100. The touch layer120may be coupled to or adhered to the cover glass110via an adhesive122that covers all of or a portion of the touch layer120.

The display stack100includes the light guide panel130. The light guide panel130may include or be formed from one or more materials configured to direct light along a planar surface. In some implementations, the light guide panel130may be used to frontlight a reflective display by directing at least a portion of light from one or more illuminators onto a portion of the reflective display. The light guide panel130may be coupled to one or more components of the display stack100with adhesive132. The adhesive132may be different than the adhesive122.

The display stack100includes the display panel150. The display panel150may be any suitable display panel150, such as those described herein, including an electrophoretic display, a liquid crystal display, or another type of display panel. The display panel150may form a bottom layer, or an outer layer, of the display stack100.

The display stack100includes the light sensor140coupled to the light guide panel130. The light sensor140may be any sensor configured to measure and/or detect ambient light, such as an ambient light sensor. The light sensor140may be arranged or positioned entirely within a chassis of a device, such that at least a portion of ambient light that impinges on the light guide panel130is communicated to the light sensor140.

The light sensor140may be configured to approximate a human eye response to light intensity. The light sensor140may be a photodiode configured to convert light into a voltage or current. Ambient light may enter the light sensor140through a detection window142, which may correspond to a top of a photodiode. The light sensor140may have any spectral response, such as a spectral response ranging from 350 nm to 1100 nm with peak sensitivity around 880 nm, or from 400 nm to 700 nm with peak sensitivity at 560 nm.

The light sensor140may be coupled to the light guide panel130via an optically clear adhesive144. The optically clear adhesive144may be positioned in between the detection window142of the light sensor140and the light guide130. The optically clear adhesive144may have a refractive index value that is less than or equal to the refractive index value of the detection window142of the light sensor140. The optically clear adhesive144may have a refractive index value that is greater than or equal to the refractive index value of the light guide panel130. In some embodiments, the optically clear adhesive144may have a refractive index value that is both less than the refractive index value of the detection window142, or another component of the light sensor140, and greater than the refractive index value of the light guide panel130.

A refractive index value of an optical medium, such as the cover glass112, the detection window142, or the light guide panel130of the display stack100, is a dimensionless number that indicates how light, or any other radiation, propagates through that specific medium. A refractive index value of a specific medium is defined as n=c/v where c is the speed of light in vacuum and v is the speed of light in the substance. For example, the refractive index value of water is 1.33, meaning that light travels 1.33 times faster in a vacuum than it does in water. Other methods of calculating or measuring refractive index values may be used herein.

The optically clear adhesive144that couples the light sensor140to the light guide panel130may be in liquid or non-liquid form. Liquid optically clear adhesive may be liquid-based and may bind the light guide panel130to the light sensor140. The optically clear adhesive144may improve optical characteristics of the device, as well as durability. Liquid optically clear adhesives may be malleable and/or less firm than other adhesives, and may therefore bind to non-even surfaces. Non-liquid optically clear adhesives, such as optically clear adhesive tape, may be used to bind one or more layers of the display stack100together. For example, the cover glass110may be coupled to the touch layer120with optically clear adhesive tape. Optically clear adhesive may be cured via ultraviolet light, heat, moisture, or a combination thereof. Optically clear adhesive may also reduce or eliminate an air gap between components or layers of the display stack100.

The optically clear adhesive144may be formed as a layer in between all or a portion of the light sensor140and the light guide panel130. For example, the optically clear adhesive144may cover only the detector window142of the light sensor140, such that ambient light propagating within, or trapped inside, the light guide panel130may escape to or otherwise propagate to the light sensor140.

By coupling the light sensor140to the light guide panel130with the optically clear adhesive144having a specific refractive index value between that of the detector window142and the light guide panel130, light may be prevented from escaping the light guide panel130and may propagate to the light sensor140, facilitating measurement of ambient light by the light sensor140without being exposed directly to the ambient light.

For example, inFIG. 1, in a first detailed view160of section A of the light guide panel130, the light sensor140may be positioned on a top surface132of the light guide panel130, with the detection window142facing the light guide panel130instead of the top of the display stack100or the ambient environment. Such an arrangement is facilitated by the coupling of the light sensor140to the light guide panel130. Ambient light, illustrated as path134, may pass through the light guide panel130and be measurable by the light sensor140. In a second detailed view170, an alternate embodiment illustrating the light sensor140coupled to a bottom surface136of the light guide panel130, with the detection window142facing the bottom surface136of the light guide panel130. Ambient light, again illustrated as path134, may similarly pass through the light guide panel130and be measureable by the light sensor140. Although positioned on “top” or “bottom” surfaces in the embodiment illustrated inFIG. 1, the light sensor130may be positioned along other surfaces of the light guide panel130, including diagonal or angled surfaces, middle surfaces, or other surfaces. Also, while illustrated as being positioned in a specific location, or near an edge, of the light guide panel130, the light sensor140may be positioned elsewhere about surfaces of the light guide panel130.

The light guide panel130may include one or more edge features138, which may be a series of one or more angles forming a “triangular formation” along all or a portion of an edge of the light guide panel130. The edge features138may facilitate directing of ambient light to the light sensor140, as described herein.

The light guide panel130may further include one or more surface features146. Surface features146may include patterning, engraving, or other formation of features on a surface of the light guide panel130that affect stray light or light streaking that may be visible to users. The surface features146may be positioned in between the light sensor140and the surface of the light guide panel130upon which the light sensor140is mounted. The surface features146may include raised portions that extend from a surface of the light guide panel130. Raised portions may be in the form of rectangles, triangles, prisms, or other formations. In some embodiments, such as the illustration in the first detailed view160, one or more surface features may be included on the surface of the light guide panel130opposite the surface upon which the light sensor140is mounted. In detailed view160, while the light sensor140is mounted on the top surface132, one or more surface features146may be included in between the light sensor140and the light guide panel130, and/or on the opposite surface, or bottom surface136of the light guide panel130. Some embodiments may include surface features146on both the surface upon which the light sensor140is mounted, as well as a portion of the opposing surface. In such embodiments, the surface features may be the same, or may be different. For example, the top surface may have cylindrical surface features while the bottom surface may have rectangular surfaces. In some embodiments, surface features146may cover a portion of the light guide panel surface that is about 3 times or 4 times the size of the detection window of the light sensor140. The area of the light guide panel130surface local to the light sensor140may more effectively redirect ambient light via the surface features146. Other examples of surface features include blazed grating type patterns and standard prismatic type patterns. The surface features146may redirect ambient light so as to turn the ambient light 90 degrees, in some embodiments.

Stray light may be light emitted from the display panel150of the display stack100that does not reflect from a display surface of the device in which the display stack100is included. Coupling patterns or surface features146of the light guide panel130of the display stack100may be arranged such that light emitted from the display panel150is propagated to the display surface at high efficiency and with minimal loss. Stray light may include polarized light reflected from pattern elements or surface features146upwards to the display window of the device. In one example, the refractive index difference between a light guide formed of polycarbonate material, where n=1.59 and an acrylic optically clear adhesive, where n=1.48, may be relatively low, or about 0.11. The same light guide, however, in air having a refractive index value of n=1 has a relatively high index difference of 0.59. Reflection power may decrease with decreasing refractive index differences, which may result in a front light display stack having significantly less stray light than a non-laminated light guide on top of a display.

Light streaking is a typical stray light pattern that may be visible to users as streaks of light that appear significantly brighter in a bare light guide compared to a laminated light guide. In a laminated light guide, light streaking may be faintly visible, if visible at all, when an electrophoretic display is black. Light streaking may be formed or caused by angular mapping of pixels, for example, where pixels in one row are facing two directions at a fifty percent split.

With the configuration illustrated inFIG. 1, the light guide panel130acts to collect ambient light from a significantly larger area than a single aperture included in devices for which a light sensor must be exposed directly to ambient light. As a result, measurement of the actual ambient light level is improved by reducing the likelihood or severity of occlusion by the user or an accessory. Furthermore, no penetrations for the ambient light sensor are required, improving the functionality and aesthetics of the device.

Accordingly, the systems, methods, computer-readable media, techniques, and methodologies described herein may detect ambient light with a light sensor coupled to a light guide panel. In some embodiments, the light sensor may be positioned on a top or bottom surface, as defined herein, of the light guide panel. The light guide panel may have edges formed so as to facilitate propagation of light from the light guide panel to the light sensor. Surface features may reduce light streaking or stray light visible to users. Although discussed herein in the context of e-readers, the systems, methods, and apparatuses of the disclosure may be applicable to other electronic devices.

One or more illustrative embodiments of the disclosure have been described above. The above-described embodiments are merely illustrative of the scope of this disclosure and are not intended to be limiting in any way. Accordingly, variations, modifications, and equivalents of embodiments disclosed herein are also within the scope of this disclosure. The above-described embodiments and additional and/or alternative embodiments of the disclosure will be described in detail hereinafter through reference to the accompanying drawings. The techniques are described below with reference to the following devices and processes. However, a number of other devices may also employ these techniques. WhileFIG. 1illustrates one example display stack, multiple other forms of display stacks, devices, and architectures may be included in other embodiments.

ILLUSTRATIVE EMBODIMENTS AND PROCESSES

FIG. 2illustrates an example environment200which may include ambient light202and a device204in accordance with one or more embodiments of the disclosure.FIGS. 3-7 and 8A-8Billustrate portions of the device204in detail and will be discussed in conjunction with the environment200ofFIG. 2. The device204may comprise an electronic book (“e-Book”) reader device, a computer display, a portable computer, a smartphone, a tablet computer, a game console, a television, an in-vehicle display, and so forth. For clarity of illustration, the figures in this disclosure are not depicted to scale. For ease of description, three axes orthogonal to one another are shown, designated as X, Y, and Z.

The ambient light202, when present, may be provided by artificial lighting such as a light bulb, by natural lighting such as the sun, or a combination. The ambient light202may be provided by a point source such as the sun or other highly localized source, or a diffuse source such as a cloudy sky. The ambient light may comprise photons in infrared wavelengths, visible wavelengths, ultraviolet wavelengths, or a combination thereof.

The device204may include a display window206through which users may view a display208of the device204. The device204may include a display stack210as described herein, such as display stack100. The display stack210of the device204may include a cover glass layer212made of glass. The cover glass layer212may form an outermost layer of the display stack210of the device204. The device204may include a chassis220that houses some or all components of the device204and the display stack210. As shown in the partial cutaway view ofFIG. 2, the device204may include a light sensor230, such as an ambient light sensor or the light sensor140ofFIG. 1.

The ambient light202may impinge on at least a portion of the device204. The device204may include the display208which may be configured to present visual information to a user. The display208may be emissive or reflective. An emissive display emits light to form an image. Emissive displays include, but are not limited to, backlit liquid crystal displays, plasma displays, cathode ray tubes, light-emitting diodes, image projectors, and so forth. Reflective displays use incident light to form an image. This incident light may be provided by the sun, general illumination in the room, a reading light, a frontlight, and so forth. Reflective displays include electro-optical displays such as electrophoretic displays, cholesteric displays, electrowetting, and so forth, as well as interferometric and other displays. For example, the electrophoretic displays may comprise an electrophoretic material configured such that when electricity is applied an image may be formed. The display208may be configured to present images in monochrome, color, or both. In some implementations, the display may use emissive, reflective, or combination displays with emissive and reflective elements.

Referring toFIG. 3, a partial cross-sectional side view along line “C” of the device204is depicted. InFIG. 3, a “front”222side and a “back” side224of the device204is identified. The front side222may be the side of the device204that includes the display208or where users are presented content or information. The back side224may be a side opposite the front side222. The front side222may be considered a “top” side or surface, and the back side224may be considered a “bottom” side or surface, as determined by a positioning or orientation of the device204. In the partial cross sectional view ofFIG. 3, light guide panel240is arranged in front of a display panel250. The light guide panel240may be substantially planar and may be formed of one or more materials such as plastic, glass, aerogel, metal, ceramic, and so forth. The light guide panel240may be laminated to the display panel250. Around a perimeter226of the light guide panel240(shown inFIG. 2) are one or more edges, such as edge228inFIG. 3. The edge228is depicted inFIG. 3as being planar and generally perpendicular to the plane of the light guide panel240. However, in other implementations, the edge228may be concave, convex, tapered, or have other shapes.

The light guide panel240may be configured with one or more surface features242on a surface thereof, or embedded within, which are configured to direct light along pre-determined paths. The surface features242may be diffractive, refractive, reflective, and so forth. The surface features242may include diffusers, grooves, grating, dimples, lenses, planar surfaces, concave surfaces, convex surfaces, and so forth, may be used to enhance or attenuate the transmission of light. In some implementations, optical features may be internal to the light guide panel240instead of, or in addition to, surface features242. For example, regions with materials of differing indices of refraction may be used to form internal features to direct light within the light guide panel240or to interface points such as proximate to the one or more illuminators260, lights sensors230, the front of the display panel250, and so forth.

In some implementations where the display panel250comprises a reflective display, the light guide panel240may be optically coupled to the one or more illuminators260and may be configured to distribute at least a portion of light emitted from one or more illuminators260to the front side222or front surface of the display panel250. In some implementations the illuminators260may be configured to provide backlighting to the display panel250. The illuminators260are shown here in a cutaway view of the interior of the chassis220to provide front lighting to the display panel250.

The one or more illuminators260may be configured to emit light when activated. The light emitted may comprise photons in infrared wavelengths, visible wavelengths, ultraviolet wavelengths, or a combination thereof. Each illuminator260may comprise one or more light-emitting diodes (“LED”), cold cathode fluorescent lamp (“CCFL”), electroluminescent materials, sonoluminescent materials, fluorescent lights, incandescent lights, or a combination thereof. In some implementations, different types of illuminators260may be used in the same device204. For example, electroluminescent lights may be used in conjunction with LEDs. The one or more illuminators260may be arranged along one or more edges of the perimeter226of the light guide panel240. The one or more illuminators260may be adjacent to and may be optically coupled to the light guide panel240such that light emitted from the one or more illuminators260is distributed to at least a portion of the display panel250.

The optical coupling between the light guide panel240and the one or more illuminators260may include one or more of physical proximity, an air gap, an adhesive, a mechanical interface, and so forth. In some implementations, one or more surface features may be provided on the illuminator110. These surface features, such as diffusers, grooves, grating, dimples, lenses, planar surfaces, concave surfaces, convex surfaces, and so forth, may be used to enhance or attenuate the transmission of light between the one or more illuminators260and the light guide panel240. In some implementations, these surface features may be separate or discrete elements which have been coupled to the light guide panel240. For example, a microlens array may be adhered to the light guide panel240to aid the optical coupling with an illuminator260.

The illuminator260is shown optically coupled to one of the edges228of the light guide panel240. In one implementation, the illuminator260may comprise a side-firing light emitting diode, with an emission side abutting the edge228. The light guide panel240is configured to distribute at least a portion of emitted light244(with illustrative rays shown here with dashed lines) from the one or more illuminators260to the front side252of the display panel250. This distribution of emitted light244serves to frontlight or illuminate the display panel250and the image presented thereon.

The one or more light sensors230are configured to detect a flux of incident photons, such as those directed by the light guide panel240, and provide a signal indicative of that flux. The incident photons may comprise photons in infrared, visible, or ultraviolet wavelengths, or a combination thereof. The light sensor230may comprise a photocell, a phototransistor, a photoresistor, photodiodes, reverse-biased LED, and so forth. In some implementations, at least a portion of the one or more illuminators260may be used as a light sensor. For example, where the illuminator260comprises an LED, it may be reverse-biased to generate a signal indicative of incident photons. The light sensor230may comprise an analog, digital, or mixed analog-digital device. The one or more light sensors230may be configured to detect one or more of visible light, infrared, or ultraviolet. In some implementations, different types of light sensors230may be used on the same device204. For example, one light sensor230sensitive to near infrared may be used as well as another light sensor230sensitive to visible light.

The light sensor230is also shown optically coupled to the light guide panel240such that at least a portion of ambient light202(with rays shown here with dotted lines) incident upon the light guide panel240is directed to the one or more light sensors230. The light sensor230is optically coupled to the light guide panel240with an optically clear adhesive layer232having a refractive index value in between a refractive index value of the light guide panel240and a detector window234of the light sensor230. In some implementations the light sensor230may comprise a diffusive material, such as a milky or translucent material, in the optical path. Although light sensors230are illustrated as positioned on the front side222and the back side224of the light guide panel240, some embodiments may include a single light sensor230positioned on any surface of the light guide panel240. The light sensor230may be positioned on any surface with a detection window facing in any direction such that the light sensor230receives ambient light propagating through the light guide panel240. In this illustration, the light sensor230is proximate to the one or more illuminators260near the same edge228of the light guide panel240. Interaction between the ambient light202and the emitted light244while propagating within the light guide panel240is minimal, such that the rays do not interfere with one another to a substantial degree. While inFIG. 2the illuminators260and the light sensor230are on a same edge of the light guide panel240, in other embodiments the illuminators and the light sensor may be positioned elsewhere.

One or more surface features246on the light guide panel240may be provided at an interface of the optical coupling between the light guide panel240and the one or more light sensors230. The surface features246may provide for light out-coupling points or light in-coupling points. Light out-coupling points are designed to facilitate light to be passed from the light guide panel240to the light sensor230, whereas light in-coupling points are designed to allow light to be passed from the one or more illuminators260to the light guide panel240. In some implementations, a light in-coupling point and a light out-coupling point may be combined into a common structure. Surface features246may comprise one or more of a diffuser, groove, grating, dimple, lens, planar surface, concave surface, or convex surface. Surface features246may be embossed, impressed, etched, and so forth. Surface features246may be separate or discrete elements which have been coupled to the light guide panel240.

The positioning and placement of the one or more light sensors230is described below in more detail with regard toFIGS. 4-7. Referring now toFIG. 4, a top view of a light guide panel300in accordance with one or more embodiments is illustrated. InFIG. 4, the light guide panel300may have a first triangular edge302, or angled surfaces forming edge302, with a first light sensor310positioned adjacently. The first light sensor310may be coupled to a top surface304of the light guide panel300with an optically clear adhesive320having a refractive index value in between that of the light guide panel300and a detector window or other component of the first light sensor310. In addition to the first light sensor310, or instead of the first light sensor310, a second light sensor330may be coupled to a bottom surface308adjacent to a second triangular edge312. The second light sensor330may also be coupled to the light guide panel300with an optically clear adhesive332having a refractive index value in between that of the light guide panel300and a detector window or other component of the first light sensor330. The shaped edges302,312may facilitate propagation of ambient light through the light guide panel300to the respective light sensor310,330. Although illustrated as having opposite edges with shaped features, shaped edges may be at adjacent edges in some embodiments and some embodiments may include planar or flat edges instead of shaped edges.

Referring now toFIG. 5, another embodiment of a display stack400in accordance with one or more embodiments of the disclosure is depicted. The display stack400includes a cover glass layer410formed of a glass at a top position402. Although referred to as “top” and “bottom” inFIG. 5, the orientation of the display stack400may affect whether any layer is a top or bottom or positioning with respect to other components in the display stack400.

In some embodiments, such as the illustration ofFIG. 5, the display stack400may include one or more touch layers, such as a first touch layer430and a second touch layer432. The first and second touch layers430,432may be coupled underneath or adjacent to a bottom or lower surface of the cover glass layer410with an adhesive layer420. The adhesive layer420may be a liquid or solid adhesive. The first and second touch layers430,432may be positioned elsewhere within the display stack400.

The display stack400includes a light guide panel450that may be coupled to, for example, the second touch layer432with adhesive layer440. The light guide panel450may be formed of material having a first refractive index value. Adhesive layer440may be formed from any suitable adhesive. In some embodiments, the light guide panel450may be optically coupled to the cover glass layer410, and may include a first surface, such as a top surface aligned with or parallel to the cover glass layer410. The light guide panel450may include a second surface opposite the first surface and a third surface forming an edge of the light guide panel450. For example, a third surface452may form an edge of the light guide panel450and may be perpendicular to the top and bottom surfaces of the light guide panel450. In other embodiments, the third surface of the light guide panel450may be transverse to the first surface and the second surface. The third surface may include a plurality of angled surfaces configured to form a triangular edge arrangement that directs ambient light from the light guide panel450to a light sensor. The light guide panel450may include a surface feature on at least a portion of the light guide panel450to provide for the optical coupling between the light guide panel450and a light sensor. The surface features on the light guide panel450may be positioned at an interface of optical coupling between the light guide panel450and a light sensor.

The display stack400may include a display panel490optically coupled to the light guide panel450via an adhesive layer480. The display panel490may be an electrophoretic display panel, an emissive display, or another display.

The display stack400includes a light sensor460coupled to the light guide panel450with an optically clear adhesive layer470having a refractive index value in between that of the light guide panel450and the light sensor460. Specifically, the adhesive layer470that optically couples the light sensor460to the light guide450may have a third refractive index value equal to or greater than the first refractive index value and equal to or less than the second refractive index value. The light sensor460may be positioned on a top or bottom surface of the light guide panel450. The light sensor460may be positioned such that at least a portion of ambient light incident upon the light guide panel is directed to the light sensor460, and may include a detection window462having a second refractive index value that is different than the first refractive index value of the light guide panel450. The light sensor460may be positioned such that the light sensor460measures only light from the light guide panel450and does not receive any light from any other source, such as direct ambient light.

Referring now toFIG. 6, the display stack400is depicted with ambient light following path492through the light guide panel450of the display stack400. The ambient light492may be trapped within the light guide panel450until impinging upon the optically clear adhesive layer470, which may facilitate passing or escaping of the ambient light from the light guide panel450to the light sensor460for measurement.

InFIG. 7, some embodiments of the display stacks of the disclosure may include mounting points or mounting surfaces on light guide panels to enhance light transmission between the light guide panel and light sensors mounted on the mounting point. For example, inFIG. 7, a light guide panel500may have a mounting point510with a light sensor520mounted thereon via an optically clear adhesive layer540. The optically clear adhesive layer540may have a refractive index value in between, or equal to, refractive index values of the light guide panel500and a component of the light sensor520. The mounting point510may be positioned on any surface, such as the top surface or the bottom surface, of the light guide panel500. The mounting point510may be positioned adjacent to an edge530of the light guide panel500. The edge530may have the angled triangular feature described above or another feature configured to further facilitate light transmission from the light guide panel500to the light sensor520. The mounting point510may form a raised portion on a second surface of the light guide panel500.

Referring now toFIGS. 8A and 8B, an example first surface feature600is illustrated inFIG. 8Aand an example second surface feature620is illustrated inFIG. 8B. The surface features600,620may be positioned on a surface of a light guide panel of display stacks as described herein. The first surface feature600may include a series of identical or different sized parallel raised rectangular or box-like portions610forming angled patterns612. The second surface feature620may include a series of raised circular or cylindrical portions622spread across all of or a portion of a surface of the light guide panel, for example, forming a desired pattern. The cylindrical portions622may extend from a rounded base626and may have varying or different radii.

FIG. 9illustrates a flow diagram of a process700of manufacturing a display stack as described herein. The following operations may be performed by manual, automated, or combined automated and manual operations.

At block702, the process700includes providing a display panel. Block704includes optically coupling a first surface of a light guide panel to a front surface of the display panel, the light guide panel comprising a first refractive index value. Block706includes optically coupling at least one touch layer to a second surface of the light guide panel. Block708includes optically coupling a cover glass layer to the at least one touch layer, such that ambient light passes through the cover glass to the light guide panel. Block710includes optically coupling an ambient light sensor to either the first surface or the second surface of the light guide panel with an optically clear adhesive, wherein the ambient light sensor has a second refractive index value and the optically clear adhesive has a third refractive index value that is greater than the first refractive index value and less than the second refractive index value.

In other embodiments, process700may include forming an edge of the light guide panel with a plurality of angled surfaces configured to form a triangular arrangement that directs ambient light from the light guide panel to the ambient light sensor. Process700may also include forming a surface feature on at least a portion of the light guide panel to provide for the optical coupling between the light guide panel and the ambient light sensor, the surface feature comprising one or more of a diffuser, groove, grating, dimple, lens, planar surface, concave surface, or convex surface. Process700may also include mounting one or more illuminators to the light guide panel, wherein the light guide panel is configured to distribute at least a portion of light emitted from one or more illuminators to the front side of the display panel.

It should be noted, that the process700may be modified in various ways in accordance with certain embodiments of the disclosure. For example, one or more operations of process700may be eliminated or executed out of the illustrated order in other embodiments of the disclosure. Additionally, other operations may be added to process700in accordance with other embodiments of the disclosure.

FIG. 10is a schematic depiction of example components of a mobile device800with an optical or display stack as described herein. The mobile device800may be any suitable user device including, but not limited to, a mobile device such as a smartphone, a tablet, an e-reader, or the like; a desktop computer; a laptop computer, a game console, a personal media player, and so forth. The mobile device800may present user interfaces and may receive input from users, such as voice commands.

In an illustrative configuration, the mobile device800may include one or more processor(s)810, one or more network interface(s)820, one or more display stacks830, one or more input/output (“I/O”) interface(s)840, one or more antennas850, and one or more memory devices860(hereinafter referred to as “memory860”). The mobile device800may also include various additional components, such as one or more input/output device(s) configured to interact with the I/O interface840to allow a user to provide input to and/or receive output from the mobile device800. The mobile device800may also include an operating system configured to provide an interface between software and hardware resources of the mobile device800, and/or database management systems configured to support functionality for storing and retrieving data in one or more datastores (which may include the memory860). The mobile device800may further include system buses that functionally couple various components of the mobile device800. In other embodiments, the mobile device800may include additional or fewer components.

The network interface(s)820may be configured to allow the mobile device800to communicate with content providers and other entities over networks, such as local-area networks (LANs), wide-area networks (WANs), the Internet, wireless networks, wireless wide-area networks (WWANs), cable television networks, telephone networks, cellular communications networks, combinations of the foregoing, and/or the like. Further, such networks may have any suitable communication range associated therewith and may include, for example, metropolitan area networks (MANs) or personal area networks (PANs). In addition, such networks may include communication links and associated networking devices (e.g., link-layer switches, routers, etc.) for transmitting network traffic over any suitable type of medium including, but not limited to, coaxial cable, twisted-pair wire (e.g., twisted-pair copper wire), optical fiber, a hybrid fiber-coaxial (HFC) medium, a microwave medium, a radio frequency communication medium, a satellite communication medium, or any combination thereof.

The display stack830may comprise any component as described herein, such as a cover glass, a cover glass layer, a plastic cover layer, a plastic frame with anti-glare coating, a plastic frame, one or more touch layers, a light guide panel, a display panel, liquid or tape optically clear adhesives, amongst other components.

One or more input/output (I/O) interfaces820may be provided that may facilitate the receipt of input information by the mobile device800from one or more I/O devices as well as the output of information from the mobile device800to the one or more I/O devices. The I/O devices may include, for example, one or more user interface devices that facilitate interaction between a user and the mobile device800including, but not limited to, a display, a keypad, a pointing device, a control panel, a touch screen display, a remote control device, a microphone, a speaker, and so forth. The I/O devices may further include, for example, any number of peripheral devices such as data storage devices, printing devices, and so forth.

The mobile device800may include one or more antennas850capable of receiving and transmitting signals in accordance with any suitable communications protocol(s). Non-limiting examples of suitable antennas may include directional antennas, non-directional antennas, dipole antennas, folded dipole antennas, patch antennas, multiple-input multiple-output (MIMO) antennas, or the like. The antenna850may be communicatively coupled to one or more transceivers or radio components870to which or from which signals may be transmitted or received. The antenna850of the mobile device800may include, without limitation, a cellular antenna for transmitting or receiving signals to/from a cellular network infrastructure, such as Global System for Mobile Communications (GSM), 3G standards (e.g., Universal Mobile Telecommunications System (UMTS), Wideband Code Division Multiple Access (W-CDMA), CDMA2000, etc.), 4G standards (e.g., Long-Term Evolution (LTE), WiMax, etc.), 5G standards, direct satellite communications, or the like. Other example antennas850include a Global Navigation Satellite System (GNSS) antenna for receiving GNSS signals from a GNSS satellite, a Bluetooth antenna for transmitting or receiving Bluetooth signals, a Near Field Communication (NFC) antenna for transmitting or receiving NFC signals, and so forth.

The antenna850may additionally, or alternatively, include a Wi-Fi antenna configured to transmit or receive signals in accordance with established standards and protocols, such as the IEEE 802.11 family of standards, including via 2.4 GHz channels (e.g. 802.11b, 802.11g, 802.11n), 5 GHz channels (e.g. 802.11n, 802.11ac), or 60 GHZ channels (e.g. 802.11ad). In alternative example embodiments, the antenna850may be configured to transmit or receive radio frequency signals within any suitable frequency range forming part of the unlicensed portion of the radio spectrum.

The mobile device800may further include a radio870for, in cooperation with the antenna126, transmitting or receiving radio frequency (RF) signals in the bandwidth and/or channels corresponding to the communications protocols utilized by the mobile device800to communicate with other devices. The radio/transceiver870may include hardware, software, and/or firmware for modulating, transmitting, or receiving, potentially in cooperation with any of antenna(s)850, communications signals according to any of the communications protocols discussed above including, but not limited to, one or more Wi-Fi and/or Wi-Fi direct protocols, as standardized by the IEEE 802.11 standards, one or more non-Wi-Fi protocols, or one or more cellular communications protocols or standards. The radio870may include any known receiver and baseband suitable for communicating via the communications protocols utilized by the mobile device800.

The memory860may include one or more program modules, applications, or the like. Any of the modules may include one or more sub-modules. The memory860of the mobile device800may include volatile memory (memory that maintains its state when supplied with power) such as random access memory (RAM) and/or non-volatile memory (memory that maintains its state even when not supplied with power) such as read-only memory (ROM), flash memory, ferroelectric RAM (FRAM), and so forth. In certain example embodiments, volatile memory may enable faster read/write access than non-volatile memory. However, in certain other example embodiments, certain types of non-volatile memory (e.g., FRAM) may enable faster read/write access than certain types of volatile memory. The memory860may include removable and/or non-removable media which may be implemented in any method or technology for storage of information, such as computer-readable instructions, data structures, program modules, or other data.

In various implementations, the memory860may include multiple different types of memory such as various types of static random access memory (SRAM), various types of dynamic random access memory (DRAM), various types of unalterable ROM, and/or writeable variants of ROM such as electrically erasable programmable read-only memory (EEPROM), flash memory, and so forth. The memory860may include main memory as well as various forms of cache memory such as instruction cache(s), data cache(s), translation lookaside buffer(s) (TLBs), and so forth. Further, cache memory such as a data cache may be a multi-level cache organized as a hierarchy of one or more cache levels (L1, L2, etc.). Other examples of memory include EEPROM, flash memory, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage, or other magnetic storage devices, RAID storage systems, or any other medium which can be used to store the desired information and which can be accessed by a computing device.

The mobile device800may optionally include a microphone880. The microphone880may be configured to generate signals based at least in part on incident or ambient sounds. The signals generated by the microphone may be analog signals. The microphone880may be configured to receive voice input in the form of analog sound input and may generate electrical signals indicative of the analog sound which may be converted to digital data using an ADC. Although each of these components is shown in the illustrated embodiment, other embodiments may include additional or fewer components.

The display stacks described herein may result in accurate sensing of ambient light by light sensors positioned without direct exposure to ambient light. The display stacks may further facilitate positioning of light sensors away from circuit boards or other components of a device, which may increase performance of the device, reduce a physical size of the device, or increase durability and structural integrity of the device by removing a need to make a hole in the device to provide direct exposure to ambient light to the light sensor.

Although specific embodiments of the disclosure have been described, one of ordinary skill in the art will recognize that numerous other modifications and alternative embodiments are within the scope of the disclosure. Further, while various illustrative implementations and architectures have been described in accordance with embodiments of the disclosure, one of ordinary skill in the art will appreciate that numerous other modifications to the illustrative implementations and architectures described herein are also within the scope of this disclosure.