INFRARED FLUORESCENT BACKLIGHT FOR OPTICAL TOUCH AND FINGERPRINT

Methods, systems, computer-readable media, and apparatuses for biometric imaging are presented. The biometric imaging can include emitting light, using a light emitter, wherein the emitted light passes through a display comprising quantum dots. The quantum dots can be configured to emit non-visible light. The biometric imaging can further include sensing, using a sensor, the non-visible light emitted from the quantum dots and reflected from an object to be imaged.

BACKGROUND

Aspects of the disclosure relate to biometric imaging systems for mobile devices.

Today, mobile devices can be multi-functional devices (e.g., smartphones) that can be used for a wide variety of purposes including social interaction, financial transactions, personal healthcare management, work-related communications, business dealings, etc. As such, these devices can store and/or display confidential and/or sensitive data. Biometric (e.g., fingerprint) recognition on mobile devices can provide an enhanced level of device security for a user (e.g., owner) of the mobile device, as it can be difficult to duplicate or imitate the user's biometric data. Additionally, biometric sensors can offer a level of convenience by enabling quick, secure access to a mobile device.

As mobile devices become more complex, space allocated to each component of a mobile device becomes increasingly constrained. In response, biometric sensors for mobile devices, including fingerprint sensors, are becoming increasingly integrated and miniaturized. Space constraints within mobile electronic devices can make integrating, positioning, and configuring biometric sensors difficult, especially while maintaining sufficient system performance necessary to consistently and accurately perform biometric scans for authenticating a user of a mobile device.

Accordingly, a need exists for improved biometric imaging systems for mobile devices.

BRIEF SUMMARY

Certain embodiments are described pertaining to biometric imaging. For example, a biometric imaging system may include a light emitter, a sensor, a cover glass, and a quantum dot element disposed between the light emitter and the cover glass. The quantum dot element can be configured to emit non-visible light in response to light emitted by the light emitter being incident upon the quantum dot element. The quantum dot element can be configured to emit the non-visible light through the cover glass at an angle less than a critical angle of the cover glass to preclude the non-visible light from totally internally reflecting within the cover glass prior to reflecting from a biometric object. The sensor can be configured to detect non-visible light reflected from the object.

The sensor can be further configured to detect the non-visible light reflected from the object when the object contacts the surface of the cover glass. The non-visible light can totally internally reflect within the cover glass after reflecting from the object before being detected by the sensor. The system can further include a Liquid Crystal Display (LCD) pixel disposed between the quantum dot element and the cover glass, wherein the non-visible light passes through the LCD. The quantum dot element can be further configured to emit visible light in response to the light emitted by the light emitter incident upon the quantum dot element. The quantum dot element can be further configured to emit the visible light at two or more different wavelengths, the two or more different wavelengths corresponding to visible colors.

The quantum dot element can be further configured to emit each of the two or more different wavelengths through a respective cell of an LCD. The two or more different wavelengths include wavelengths corresponding to red, blue, and green colors of light. The quantum dot element can be further configured to emit the non-visible light through a cell of the LCD. The sensor can includes an imaging sensor configured to capture an image of the object using the non-visible light. The non-visible light can include infrared light.

In certain embodiments, a method is disclosed including emitting light, at a light emitter. The method can further include emitting non-visible light, at a quantum dot element, in response to the light emitted by the light emitter being incident upon the quantum dot element. The non-visible light can be emitted through the cover glass at an angle less than a critical angle of the cover glass to preclude the non-visible light from totally internally reflecting within the cover glass prior to reflecting from a biometric object. The method can also include detecting, at a sensor, non-visible light reflected from the object.

The non-visible light can be totally internally reflected within the cover glass after reflecting from the object and before being detected by the sensor. The method can further include emitting visible light, at the quantum dot element, in response to the light emitted by the light emitter being incident upon the quantum dot element. The method can also include emitting, at the quantum dot element, two or more different wavelengths of light corresponding to visible colors. The method can additionally include emitting the two or more different wavelengths, at the quantum dot element, through a respective cell of a LCD. The two or more different wavelengths can correspond to visible colors including red, blue, and green colors of light. The method can also include emitting each of the two or more different wavelengths through a respective cell of the LCD. The method can additionally include capturing an image of the object using the non-visible light at the sensor.

In certain embodiments, an imaging system is disclosed including a means to emit light, a means to sense light, and a means to emit non-visible light in response to light emitted by the means to emit light being incident upon the means to emit non-visible light. The means to emit non-visible light can be configured to emit the non-visible light through the cover glass at an angle less than a critical angle of the cover glass to preclude the non-visible light from totally internally reflecting within the cover glass prior to reflecting from a biometric object. The means to sense light can be configured to detect non-visible light reflected from the object.

DETAILED DESCRIPTION

Several illustrative embodiments will now be described with respect to the accompanying drawings, which form a part hereof. While particular embodiments, in which one or more aspects of the disclosure may be implemented, are described below, other embodiments may be used and various modifications may be made without departing from the scope of the disclosure or the spirit of the appended claims.

Display devices for use in mobile device (e.g., smartphones, tables, laptops, etc.) and other devices can utilize Liquid Crystal Display (LCD), Organic Light Emitting Diode (OLED) or other display technologies to display images to a user. These display technologies can utilize a cover glass to form a barrier between display components and an environment external to the display (and a user of the mobile device). As used herein, a cover glass is a component of a display in which a user can make direct contact using an appendage. A cover glass does not need be made of glass and can contain various polymers, glasses, or other materials in any combination. Thus, a cover glass can form a barrier to protect display component(s) from dust, oil, damage due to pressure, or other adverse conditions. A cover glass for a mobile device can also be used as an input interface through the use of various techniques (e.g., capacitance or resistive sensors, etc.). For example, smartphones routinely make use of displays with cover glasses that can be used by a user to interact with a User Interface (UI) displayed through the cover glass.

As mobile devices become more complex, space available for certain individual components (including biometric sensors) has become increasingly constrained as additional features and components are integrated into mobile devices. Additionally, physical constraints of mobile devices, to maintain portability and desires to minimize certain physical dimensions (while maintaining a relatively large display screen), have further limited space allotments for biometric sensors. For these and other reasons, it may be desirable to integrate a biometric sensor (such as a fingerprint scanner) with a display of a device.

Furthermore, a biometric imaging display can provide for more intuitive techniques for biometrically authorizing a user to access a device (or a function of a device), as compared to a dedicated biometric sensor for fingerprint imaging (or a biometric sensor combined with a physical button of a mobile device). For example, techniques disclosed herein can enable continuous authentication and/or validation of a user attempting to access a device or a specific feature of a device (e.g., banking, access to secure remote devices, etc.).

The continuous authentication can include periodically imaging a fingerprint (or a portion of a fingerprint) of a user to generate a inquiry template. The inquiry template can be compared to one or more enrolled templates. If the inquiry template is deemed to sufficiently match an enrolled template, a user can be deemed to be authenticated and/or validated for access to a device or a function of a device. If the inquiry template is not found to sufficiently match an enrolled template, the user can be denied access to the device or a function of the device. Certain enrolled templates can be associated with one or more credentials. Thus, if a user's inquiry template matches an enrolled template with insufficient privileges to access a device or a certain function of a device, a user can be denied access to that device or function. As used herein, the term fingerprint can mean a friction ridge surface of an appendage of a user. The appendage can be a finger, toe, or other. Fingerprint imaging systems can take advantage of patterns of blood vascular or other biometric systems.

Disclosed are techniques for enabling use of a cover glass of a display to function as a visual display surface as well as a fingerprint imaging surface. Thus, a user can present their finger upon a surface of a cover glass of a display, and a device using the display can image the fingerprint to validate and/or authenticate the user. In certain embodiments, non-visible light can be emitted through the cover glass of a display along with visible light. The visible light can form a UI on the display and be viewed by the user. The non-visible light can be used to image a fingerprint of the user without disrupting the user's ability to view the UI (or other information displayed via the visible light). The non-visible light can be infrared light (light with wavelength of 700 nm to 1 mm, for example). The visible light can have wavelength(s) of 400 nm to 700 nm, for example.

In certain embodiments, a quantum dot element can be used to generate visible and/or non-visible light. A quantum dot element, as used herein, is a physical object that includes one or more quantum dots. A quantum dot is a nanoscale particle comprised of semiconducting material. When excited (such as via application of light), a quantum dot can emit light at a wavelength determined by physical properties of the quantum dot. The emission at a certain wavelength can occur regardless of a wavelength of light incident upon a quantum dot. Thus, certain quantum dots can emit non-visible light and certain other quantum dots can emit visible light, regardless of whether light incident upon the quantum dots is visible or non-visible. Additionally, different wavelengths of non-visible or visible light can be emitted by quantum dots. A quantum dot element can be configured to emit various wavelengths of light from different portions of the quantum dot element. Using a quantum dot element in conjunction with a cover glass can enable non-visible and visible light to be emitted through the cover glass.

Disclosed are techniques including use of a quantum dot element to emit non-visible light through a cover glass for imaging of a biometric object (e.g., finger) of a user. The quantum dot element can be used in conjunction with Light Emitting Diode (LED), fluorescent or other backlight technologies with an LCD. The quantum dot element can be used in conjunction with OLED display technologies. Furthermore, the quantum dot element can improve color reproduction by an LCD, OLED, or other display. The quantum dot element can provide fingerprint imaging functionality in a compact and relatively inexpensive package. Thus, techniques for improving biometric imaging systems for mobile devices are disclosed.

FIG. 1illustrates a simplified diagram embodying several features of the disclosure.FIG. 1illustrates a system100that can be used as a display for a mobile device as well as a biometric sensor for imaging a biometric object114. The system100can include a cover glass102, a Liquid Crystal Display (LCD) display component104, and a backlight106. The illustrated backlight106is arranged as a light guide to guide light emitted from light emitter108. Light emitter108is arranged at an edge of the light guide. Here, backlight106is illustrated as an edge-lit backlight. It should be understood that the system disclosed can be used with a variety of backlight technologies. For example, the backlight106can be one or more light emitters arranged directly behind LCD component104. The backlight106can be a matrix backlight, a fluorescent backlight, or other. Light emitter108and/or backlight106can include a light emitting diode, fluorescent lamp, prism, reflective polarizer, or other. Light emitter108and/or backlight108can be configured to emit light at several different wavelengths, as will be further described herein.

It should be understood that the system disclosed can be used with a variety of display technologies including the disclosed LCD display. For example, LCD component104can include an array of cells that can be polarized to allow light to be transmitted there through. In particular, each cell can be arranged to attenuate light in a first state and to substantially transmit light in a second state. Each cell can be associated with a color (wavelength) of visible or non-visible light. By combining cells for attenuating primary colors (e.g., red, green, and blue), for example, a pixel of a display can be formed. By adjusting the attenuation of each cell of a pixel, the pixel can be configured to emit any color combination of the primary cell colors.

The light emitter108can be used to emit light120that can be reflected or otherwise dispersed at point122of backlight106and guided as illustrated. Redirected light124can make contact with an eye112of a user so that the user can see the images. System100can be integrated into a smartphone or other device to form a display for displaying various information to a user (e.g., emails, phone numbers, movies, games, etc.). Light emitter108can include several light emitters each configured to emit light at a substantially different wavelength (i.e., color) of light. Each color of light emitted can correspond to a different backlight106light guide or a different path/portion of a light guide of backlight106, to guide each color to a corresponding cell of LCD component104. For example, red light can be emitted and guided to LCD cells for displaying red light. Likewise, a respective emitter and backlight106can be configured for guiding green and blue light. Thus, system100is a simplified diagram of a display system.

A non-visible light emitter110can be used to emit non-visible light for biometric imaging. Non-visible light116emitted from the non-visible light emitter110can enter the cover glass102after reflecting or otherwise being diverted by backlight106. Note that a different light guide distinct from backlight106used for visible light can be used to guide non-visible light116to cover glass102or the same backlight106can be used. Non-visible light116can be used to image a biometric object placed against the cover glass102. For example, biometric object114can be a finger of a user placed against a surface118of the cover glass102. Reflected non-visible light126that has reflected after contact with the biometric object114can be received by a sensor128. Sensor128can be an imaging sensor (e.g., a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS)). In this manner, the cover glass102can be used for displaying images as well as for biometric imaging. The non-visible light116emitted from the non-visible light emitter110can be infrared, for example, so that it is not visible by a user. In this manner, the imaging of the biometric object114can occur without interfering with the ability of the system100to operate as a visible display.

Although not illustrated, sensor128and/or light emitter108or110can be coupled to a processor and/or memory. The processor can be configured to perform fingerprint template generation and matching or other biometric authentication techniques. The memory, for example, can store biometric enrollment templates to be matched to later acquired matching template(s) acquired from a user attempting to be authorized.

The cover glass102can be curved or take a variety of shapes. Additionally, it should be understood that the cover glass102can be comprised of glass or a variety of other materials and can include various coatings to improve the durability of the cover glass102or to alter optical properties of the cover glass102. Although not illustrated, LCD component104can include OLED display features which can negate the need to use backlight106. For example, each light emitting diode of an OLED display can be configured to emit light at a certain wavelength (e.g., blue, green, red, infrared). Thus, a plurality of diodes can form a pixel of a display for an OLED display. Infrared emitting diodes can be arranged across an OLED display to enable imaging of a biometric object, as disclosed herein.

FIGS. 2A and 2Billustrate simplified diagrams embodying several features of the disclosure including use of a quantum dot element202. The system200ofFIG. 2can be operable to display image(s) to a user as well as to operate as a biometric scanner using a cover glass102, similar to the system100ofFIG. 1. However, the system200ofFIG. 2is able to perform these functions without the need to use two or more separate light emitters. Instead, a single light emitter212is used to emit light for both functions.

The system200can make use of quantum dots to generate non-visible light (such as infrared light) for biometric imaging. Quantum dots are crystalline structures made of semiconductor materials and can be small enough to exhibit quantum mechanical properties wherein the quantum dot's excitons are confined in all three spatial dimensions. By confining the excitons, photons can be emitted by quantum dots at a predetermined wavelength depending on the dimensions of the crystalline structures. Therefore, a quantum dot can be excited by a photon of any wavelength (e.g., any wavelength within an operational range) and then emit a corresponding photon at a set wavelength. In this manner, a quantum dot can operate as a high efficiency converter to emit a certain wavelength of light. In other words, an element comprising quantum dots can operate somewhat analogous to a filter, but at much higher efficiency because, whereas a filter can absorb/block light of unwanted wavelength, quantum dots can convert light to different wavelengths without such absorption/blockage. Quantum dots can be made from materials such as lead sulfide, lead selenide, cadmium selenide, cadmium sulfide, indium arsenide, or indium phosphide, as well as other materials.

The system200can take advantage of properties of quantum dots to display visible and non-visible light. The system200includes a quantum dot element202that can include quantum dots. The quantum dots can each be configured to emit light at set wavelengths. Some quantum dots can be configured to emit light at a first wavelength and some quantum dots can emit light at a second wavelength. For example, quantum dot element202can include quantum dots configured to emit light with wavelengths corresponding to visible primary colors or red, green, and blue as well as infrared light. The red, green, and blue emitting quantum dots can be arranged corresponding to LCD cells of the LCD component104. Each cell can be used to make a subpixel of a displayed pixel. Each pixel can comprise subpixels of respective red, green, and blue colors to display a wide range of colors for each pixel of a displayed image. In certain embodiments, primary color emitting quantum dots can be used in conjunction with a filter corresponding to each subpixel. For example, quantum dots can be used to emit primary colors of light having relatively narrow frequency ranges centered around a primary color. Filtering can be utilized in certain embodiments to filter a respective one of primary color(s) emitted by quantum dots. Similarly, quantum dots can be arranged in multiple stages wherein primary color(s) are emitted by a first quantum dot element and then a subset of the primary color(s) are emitted by a second quantum dot element. In certain embodiments, quantum dots can be arranged in any manner of stages/arrangement to emit visible light or non-visible light at one or more wavelengths. Quantum dots can be arranged to emit infrared light in a uniform manner across cover glass102, or in certain areas or patterns on cover glass102. For example, a portion of the cover glass102can be designated to operate as a biometric scanner in order to, for example, optimize the imaging capabilities of the sensor128.

Infrared emitting quantum dots can be uniformly arranged to emit infrared light across the entire displayed image. Quantum dot element202can be arranged in various positions within system200.FIG. 2includes quantum dot element202as a separate element, but quantum dot element20can be integrated into backlight106, LCD component104, or the cover glass102, for example. Quantum dot element202dots can a film that can be applied to any of the aforementioned components. If the quantum dot element202is arranged behind LCD component104, infrared light emitted by the quantum dot element202can pass through (i.e., be un-attenuated by) LCD cells of LCD component104. For example, infrared light (or other wavelengths of non-visible light) can be un-attenuated by an LCD cell configured to attenuate a wavelength of visible light. Thus, infrared light can pass through red, green, or blue attenuating LCD cells regardless of the state of the cells. In this manner, a visible LCD display can also emit infrared light regardless of the state of LCD cells of the LCD display.

InFIG. 2A, a light emitter212is illustrated as emitting light214. The light214can make contact with a backlight106at point122and be guided to quantum dot element202. Quantum dot element202can have variously configured quantum dots to emit one or more wavelengths of light, as disclosed herein. For example, some quantum dots can emit light204at one wavelength (color). Additional quantum dots can emit light206at a second wavelength. Still additional quantum dots can emit light208at a third wavelength. Finally, other quantum dots can emit light210at a fourth wavelength. The wavelengths of light204,206, and208can fall within the visible spectrum for a human being and can correspond to, for example, red, green, and blue light. The wavelength of light210can fall outside of the visible spectrum of a human being to be used for biometric imaging using infrared light, for example.

The light emitter212can be configured to emit light214of various wavelength(s). The light214can be of the shortest wavelength of light used by the system200. For example, if the system200displays blue, green, red, and infrared light, the light214can be blue light as it has the shortest wavelength of the four types of light. Light with shorter wavelengths can be more readily converted by quantum dots to light with longer wavelengths, since most common state transitions include a single-photon that loses some energy on re-emission. Light with longer wavelengths can comprise lower energy photons. However, given the nature of quantum dots (being able to emit light at a certain wavelength regardless of a wavelength of incident light), light214can have various wavelength(s), even some that are not displayed by the system200. In certain embodiments, quantum dot element202can comprise quantum dots configured to transmit only non-visible light for biometric imaging. Such a configuration can be advantageous, for example, when retrofitting a biometric sensor to an already existing display system.

Multiple different wavelengths of non-visible or infrared light may be used in order to increase sensing capability (e.g. use different wavelengths to probe pulse-oximetry from finger, to probe different depths inside the skin, or estimate skin color spectrum). Quantum dots for emitting different wavelengths of non-visible light can be arranged in a pattern with different wavelengths in different locations. Such an arrangement can help extract position information for features of a biometric object, for example. Non-visible light for biometric imaging can be infrared light with wavelength of 700-1000 nm, e.g. 850 nm, 880 nm, and/or 940 nm.

FIG. 2Billustrates an additional path of light210used to image biometric object114. As illustrated, light214can be guided from light emitter212to quantum dot element202. Non-visible light210can be re-emitted by quantum dot element202and pass through LCD component104and through cover glass102. The non-visible light210can be reflected or otherwise dispersed by biometric object114when biometric object114makes contact with cover glass102or is otherwise presented in front of cover glass102(e.g., in the path of non-visible light210). Reflected non-visible light216from biometric object114can be received at sensor128for imaging of biometric object114. For example, biometric object114can be placed against a surface118of cover glass102, and non-visible light can reflect from biometric object114accordingly.

According to various embodiments, system200is configured to control the incident angle at which non-visible light210encounters cover glass102, in order to avoid unwanted total internal reflection when biometric object114is not in contact with cover glass102. When biometric object114is in contact with cover glass102(i.e., with surface118), reflected non-visible light216may reflect within cover glass102and be received at sensor128, as illustrated. Non-visible light216can be reflected by being scattered by biometric object114, for example. After non-visible light216is scattered or otherwise reflected by biometric object114, non-visible light216can, in certain embodiments, internally reflect within cover glass102to be received at sensor128. When biometric object114is not in contact with cover glass102, non-invisible light210is intended to be transmitted through cover glass102without reflection, resulting in no reflected non-visible light216being totally internally reflected and received at sensor128. In this manner, system200may distinguish between a contact state vs. a non-contact state. By employing multiple pixels each making such a contact vs. non-contact distinction, system200may generate a contrast image, such as a finger print image. However, if unintended reflections are also generated and received when biometric object114is not in contact with cover glass102, the distinction between the contact state and the non-contact state may become blurred, leading to degradation of the image.

In particular, unintended reflections may occur if non-visible light210encounters cover glass102at an inappropriate incident angle. The incident angle may be measured between non-visible light210and a vector normal to the plane defined by surface118. Light that encounters a transition between two different materials may reflect off of the transition, if the incident angle formed between the light and a vector normal to the plane of the transition is greater than a critical angle. The critical angle varies depending on the respective indices of refraction of the two materials. Here, if biometric object114is not making contact with surface118of cover glass102, the two materials would be the cover glass102and open air, and the critical angle would be defined accordingly. Thus, if the incident angle formed between non-visible light210and surface118is greater than the corresponding critical angle, non-visible light210would reflect off of the transition and create unintended reflections that may totally internally reflect within cover glass102and eventually reach sensor128. As used herein, the term total internal reflectance refers to light that reflects from being incident at an angle greater than a critical angle at a barrier formed between two different refractive indexes.

According to various embodiments, quantum dot element202is configured to emit non-visible light210through the cover glass at an incident angle less than the critical angle. Thus, unintended reflections during the non-contact state may be avoided. In this manner, system200may improve the quality of biometric images by increasing the contrast between contact and non-contact states and making the detection of ridges, valleys, minutiae, or other features of a fingerprint more apparent.

Although not illustrated, quantum dot element202can be used with OLED or other display techniques. For example, quantum dot element202can be used in conjunction with an array of OLED diodes that each emits light at one wavelength (blue for example). For example, certain diodes can correspond to a subpixel of a display. Red subpixels can include quantum dots configured to emit red wavelength light in response to blue light emitted from an OLED diode. Similarly, green light can be emitted even though a blue OLED diode is used to emit blue light. Any combination of subpixels or pixels can include quantum dots configured to emit non-visible light (such as infrared light). Such a configuration can enable visible light of various colors to be used in conjunction with non-visible light with an OLED display emitting light at one wavelength. An OLED configuration may have advantages in contrast and/or power consumption over an equivalent LCD configuration. Quantum dot element202can also be used in conjunction with an OLED display that displays multiple colors of light. For example, a quantum dot element202can include quantum dots that emit light at non-visible light. Such a quantum dot element202can be used in conjunction with an OLED display that emits multiple colors of visible light to enable the display to also be used for biometric imaging via non-visible light.

FIG. 3illustrates a simplified diagram of a quantum dot element interacting with LCD cells according to certain embodiments. InFIG. 3, a system300is illustrated with a backlight302, a quantum dot element328and an LCD pixel330. Quantum dot element328can be similar to quantum dot element202. LCD pixel330can be similar to LCD component104. Backlight302can be similar to backlight106. Illustrated is light318emitted at a first wavelength (e.g., blue).

Quantum dot element328is illustrated as including various sections304,306, and308each corresponding to a respective cell (310,312, and314) of LCD pixel330. As illustrated, light318emitted by backlight302can impinge upon each section304,306, and308. Each section can correspond to a color of light (for example, a primary color). Thus, each section can correspond to a subpixel. Section304, for example, includes a quantum dot configured to emit red light320(denoted by the letter “R”). Similarly, section306can include quantum dot(s) emit blue light322(denoted by the letter “B”) and section308can include quantum dot(s) emit green light324(denoted by the letter “G”). Any of sections304,306, or308can include quantum dots configured to emit non-visible light326(denoted by the letter “X”). Although each of section304,306, and308are illustrated as including a non-visible light emitting quantum dot, any of the sections can emit non-visible light in any combination.

Furthermore, it should be understood that a section (such as section306) may not include a quantum dot to emit a color of light. For example, light318can be blue light. Therefore, a quantum dot to emit blue light may not be needed.

As illustrated, LCD pixel330includes cells310,312, and314each respectively corresponding to section304,306, and308. As disclosed herein, visible light colors320,322, and324can each be attenuated by a cell310,312, or314. A pixel can comprise a plurality of cells. Thus, by attenuating distinct colors of visible light, a pixel can display any combination of the colors of attenuated light. However, non-visible light326may bass through cells310,312, and314regardless of the attenuating state of the cells. Therefore, in certain embodiments, each cell of an LCD panel can transmit non-visible light for imagining a biometric object regardless of a displayed image of the display. However, in certain embodiments, cell(s) can correspond to non-visible light for imaging a biometric object or for other purposes. A cover glass (not shown) can be included for light320,322,324, and/or326to pass through.

FIG. 4illustrates features of light emitted through a cover glass according to certain embodiments. System400includes cover glass402that can be similar to cover glass102. Light404can be emitted through cover glass402and can be similar to light210. As illustrated, an angle418to a reference normal (i.e., perpendicular) to a surface414of cover glass402can be defined. If angle418is greater than a critical angle, then total internal reflectance410of light405can occur. Here, no biometric object is in contact with cover glass402. Thus, the two relevant materials are open air401and cover glass402. Surface414can indicate a barrier between cover glass402and open air401. Open air401can have an index of refraction lower than cover glass402. The critical angle can be defined by the equation

wherein θC=the critical angle, n2=an index of refraction of the second material (open air in this instance), and n1=an index of refraction of the first material (the cover glass402in this instance).

Light that is emitted at an angle greater than a critical angle can be totally internally reflected 410 and can be detected by a sensor416. Sensor416can be similar to sensor128. Thus, reflected light410can be detected by sensor416regardless if a biometric object is present to be imaged. Reflected light410can be totally internally reflected along cover glass402before reaching sensor416. According to certain embodiments of the present disclosure, non-visible light, such as light404, can be emitted through cover glass402at an angle406less than the critical angle, precluding total internal reflectance to occur and improving an ability of the system400to image a biometric object (by reducing noise that reduces a contrast of an image of a biometric object). Note that, although not illustrated, light405can be emitted through a medium collocated next to cover glass402that can be other than air. For example, a light emitter can emit through various mediums included in, for example, light guide(s), diffusion element(s), filter(s), or other mediums.

FIG. 5illustrates a flowchart500for implementing techniques using certain embodiments. At502, a light can be emitted at a light emitter. The light can be visible light or non-visible light. The light emitter can be light emitter212, for example. At504, non-visible light can be emitted by a quantum dot element in response to light emitted by the light emitter being incident upon the quantum dot element. The quantum dot element can be, for example, quantum dot element202and the light emitted by the quantum dot element can be light204,206,208,210in response to light214emitted by light emitter212, for example.

The non-visible light can be emitted through a cover glass (such as cover glass102) at an angle less than a critical angle of the cover glass to preclude the non-visible light from totally internally reflecting within the cover glass when an object does not contact a surface of the cover glass (as described in detail regardingFIG. 4) or otherwise prior to being reflected by the object. At506, non-visible light emitted by the quantum dot element can be detected at a sensor after reflecting from an object. The object can be biometric object114, for example.

FIG. 6illustrates a flowchart600for implementing a device using certain embodiments. At602is a means to emit light. The light can be visible light or non-visible light. The means to emit light can be light emitter212, for example. At604is a means to sense light. For example, sensor128is an example means to sense light. At606is a means to emit non-visible light in response to light emitted by the means to emit light being incident upon the means to emit non-visible light. The means to emit non-visible light can, for example, be quantum dot element202.

The means to emit non-visible light can configured to emit the non-visible light through a cover glass at an angle less than a critical angle of the cover glass (e.g., cover glass102) to preclude the non-visible light from totally internally reflecting within the cover glass when an object does not contact a surface of the cover glass (as described in detail regardingFIG. 4) or otherwise prior to being reflected by the object. The means to sense light can be configured to detect non-visible light reflected from the object.

FIG. 7illustrates an example of a computing system in which one or more embodiments may be implemented.

A computer system as illustrated inFIG. 7may be incorporated as part of the above described computerized device. For example, computer system700can represent some of the components of a television, a computing device, a server, a desktop, a workstation, a control or interaction system in an automobile, a tablet, a netbook or any other suitable computing system. A computing device may be any computing device with an image capture device or input sensory unit and a user output device. An image capture device or input sensory unit may be a camera device. A user output device may be a display unit. Examples of a computing device include but are not limited to video game consoles, tablets, smart phones and any other hand-held devices.FIG. 7provides a schematic illustration of one implementation of a computer system700that can perform the methods provided by various other implementations, as described herein, and/or can function as the host computer system, a remote kiosk/terminal, a point-of-sale device, a telephonic or navigation or multimedia interface in an automobile, a computing device, a set-top box, a table computer and/or a computer system.FIG. 7is meant only to provide a generalized illustration of various components, any or all of which may be utilized as appropriate.FIG. 7, therefore, broadly illustrates how individual system elements may be implemented in a relatively separated or relatively more integrated manner.

The computer system700is shown comprising hardware elements that can be electrically coupled via a bus702(or may otherwise be in communication, as appropriate). The hardware elements may include one or more processors704, including without limitation one or more general-purpose processors and/or one or more special-purpose processors (such as digital signal processing chips, graphics processing units722, and/or the like); one or more input devices708, which can include without limitation one or more cameras, sensors, a mouse, a keyboard, a microphone configured to detect ultrasound or other sounds, and/or the like; and one or more output devices710, which can include without limitation a display unit such as the device used in implementations of the invention, a printer and/or the like. Additional cameras720may be employed for detection of user's extremities and gestures. In some implementations, input devices708may include one or more sensors such as infrared, depth, and/or ultrasound sensors. The graphics processing unit722may be used to carry out the method for real-time wiping and replacement of objects described above.

In some implementations of the implementations of the invention, various input devices708and output devices710may be embedded into interfaces such as display devices, tables, floors, walls, and window screens. Furthermore, input devices708and output devices710coupled to the processors may form multi-dimensional tracking systems.

The computer system700might also include a communications subsystem712, which can include without limitation a modem, a network card (wireless or wired), an infrared communication device, a wireless communication device and/or chipset (such as a Bluetooth device, an 802.11 device, a WiFi device, a WiMax device, cellular communication facilities, etc.), and/or the like. The communications subsystem712may permit data to be exchanged with a network, other computer systems, and/or any other devices described herein. In many implementations, the computer system700will further comprise a non-transitory working memory718, which can include a RAM or ROM device, as described above.

Substantial variations may be made in accordance with specific requirements. For example, customized hardware might also be used, and/or particular elements might be implemented in hardware, software (including portable software, such as applets, etc.), or both. Further, connection to other computing devices such as network input/output devices may be employed. In some implementations, one or more elements of the computer system700may be omitted or may be implemented separate from the illustrated system. For example, the processor704and/or other elements may be implemented separate from the input device708. In one implementation, the processor may be configured to receive images from one or more cameras that are separately implemented. In some implementations, elements in addition to those illustrated inFIG. 7may be included in the computer system700.

Some implementations may employ a computer system (such as the computer system700) to perform methods in accordance with the disclosure. For example, some or all of the procedures of the described methods may be performed by the computer system700in response to processor704executing one or more sequences of one or more instructions (which might be incorporated into the operating system714and/or other code, such as an application program716) contained in the working memory718. Such instructions may be read into the working memory718from another computer-readable medium, such as one or more of the storage device(s)706. Merely by way of example, execution of the sequences of instructions contained in the working memory718might cause the processor(s)704to perform one or more procedures of the methods described herein.

The terms “machine-readable medium” and “computer-readable medium,” as used herein, refer to any medium that participates in providing data that causes a machine to operate in a specific fashion. In some implementations implemented using the computer system700, various computer-readable media might be involved in providing instructions/code to processor(s)704for execution and/or might be used to store and/or carry such instructions/code (e.g., as signals). In many implementations, a computer-readable medium may be a physical and/or tangible storage medium. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical and/or magnetic disks, such as the storage device(s)706. Volatile media include, without limitation, dynamic memory, such as the working memory718. Transmission media include, without limitation, coaxial cables, copper wire and fiber optics, including the wires that comprise the bus702, as well as the various components of the communications subsystem712(and/or the media by which the communications sub system712provides communication with other devices). Hence, transmission media can also take the form of waves (including without limitation radio, acoustic and/or light waves, such as those generated during radio-wave and infrared data communications).

The communications subsystem712(and/or components thereof) generally will receive the signals, and the bus702then might carry the signals (and/or the data, instructions, etc. carried by the signals) to the working memory718, from which the processor(s)704retrieves and executes the instructions. The instructions received by the working memory718may optionally be stored on a non-transitory storage device706either before or after execution by the processor(s)704.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Moreover, nothing disclosed herein is intended to be dedicated to the public.