SWIPE MOTION REGISTRATION ON A FINGERPRINT SENSOR

In one aspect, a method for registering a fingerprint profile on a mobile device includes detecting, at a fingerprint detection module having a rectangular shape, a contact from a finger associated with a swipe motion. The method includes responsive to the detected contact at the fingerprint detection module having a rectangular shape, capturing an image of the finger during the swipe motion. The method includes storing the image of the finger captured during the swipe motion as a registered fingerprint profile of an authorized user.

TECHNICAL FIELD

The present disclosure generally relates to fingerprint recognition for securely accessing a mobile device.

BACKGROUND

Electronic devices including portable or mobile computing devices, such as laptops, tablets, smartphones, and gaming systems may employ user authentication mechanisms to protect personal data and prevent unauthorized access. User authentication on an electronic device may be carried out through one or multiple forms of biometric identifiers, which can be used alone or in addition to conventional password authentication methods. A popular form of biometric identifiers is a person's fingerprint pattern. A fingerprint sensor can be built into the electronic device to read a user's fingerprint pattern so that the device can only be unlocked by an authorized user of the device through authentication of the authorized user's fingerprint pattern.

SUMMARY

Embodiments described in this document provide devices, systems, and techniques that perform human fingerprint detection and authentication for authenticating an access attempt to a locked mobile device equipped with a fingerprint detection module.

In one aspect, a method for registering and recognizing a fingerprint profile on a mobile device is disclosed. The method includes operating in a fingerprint registration mode. Operating in the fingerprint registration module includes detecting, at a fingerprint detection module having a non-uniform shape, a contact from a finger associated with a swipe motion. Operating in the fingerprint registration module includes responsive to the detected contact at the fingerprint detection module having the non-uniform shape, capturing an image of the finger during the swipe motion. Operating in the fingerprint registration module includes storing the image of the finger captured during the swipe motion as a registered fingerprint profile of an authorized user. The method includes operating in a fingerprint recognition mode. Operating in the fingerprint recognition mode includes detecting a non-swipe contact from a finger of a user on the non-uniformly shaped fingerprint detection module of the mobile device while the mobile device is locked. Operating in the fingerprint recognition mode includes responsive to detecting the non-swipe contact, activating the non-uniformly shaped fingerprint detection module to capture a partial image of the finger making the non-swipe contact with the non-uniformly shaped fingerprint detection module. Operating in the fingerprint recognition mode includes comparing the captured partial image of the finger making contact with the non-uniformly shaped fingerprint detection module with the registered fingerprint profile of the authorized user of the mobile device. Operating in the fingerprint recognition mode includes responsive to the comparing, identifying the captured partial image as belonging to the authorized user and granting the user access to the locked mobile device.

The method can be implemented in various ways to includes one or more of the following features. The method can include receiving a signal indicating a fingerprint registration mode. The method can include responsive to receiving the signal indicating a fingerprint registration mode, activating the fingerprint detection module to capture the image of the finger. Capturing an image of the finger during the swipe motion can include capturing partial images of the finger in sequence during the swipe motion to accumulate a substantially complete fingerprint image to store as the registered fingerprint profile of an authorized user. Capturing an image of the finger during the swipe motion can include detecting differences between three lines of pixelated sensing elements of the rectangular shaped fingerprint detector module. The method can include analyzing the partial image of the finger captured during the swipe motion to determine whether a sufficient portion of the finger was captured to qualify as the registered fingerprint profile of an authorized user. The method can include outputting a message to instruct a user to swipe a finger across the non-uniformly shaped fingerprint detection module. The message can include at least one of audio, texts, images or videos. Comparing can include correlating the captured image of the finger with the registered fingerprint profile of an authorized user. Identifying can include when a correlation between the captured image of the finger and the registered fingerprint profile of an authorized user is statistically significant, identifying the captured image of the finger as bellowing to the authorized user. The non-uniformly shaped fingerprint detection module can include a rectangular shaped fingerprint detection module with a first number of sensor pixels in one dimension and a second number of sensing electrodes larger than the first number in another dimension. The method can include receiving a signal indicating the fingerprint recognition mode; and responsive to receiving the signal indicating the fingerprint recognition mode, activating the fingerprint detection module to operate in the fingerprint recognition mode.

In another aspect, a mobile device includes a transparent top cover. The mobile device includes a touch panel configured to receive touch input, the touch panel disposed under the transparent top cover. The mobile device includes a non-uniformly shaped fingerprint detection module to operate in a fingerprint registration mode to detect a swipe motion contact and a fingerprint recognition mode to detect a non-swipe motion contact. During the fingerprint registration mode, the non-uniformly shaped fingerprint detection module is configured to detect a contact from a finger associated with a swipe motion, responsive to the detected swipe motion contact, capturing an image of the finger, and store the image of the finger captured during the swipe motion as a registered fingerprint profile of an authorized user. During the fingerprint recognition mode, the non-uniformly shaped fingerprint detection module is configured to: detect a non-swipe contact from a finger of a user while the mobile device is locked, responsive to the detected non-swipe contact, activate the non-uniformly shaped fingerprint detection module to capture a partial image of the finger making the non-swipe contact with the non-uniformly shaped fingerprint detection module, compare the captured partial image of the finger making contact with the non-uniformly shaped fingerprint detection module with the registered fingerprint profile of the authorized user of the mobile device, and identify the captured partial image as belonging to the authorized user and granting the user access to the locked mobile device.

The mobile device can be implemented in various ways to include one or more of the following features. The rectangular shaped fingerprint detection module can be embedded in the transparent top cover to expose a top surface of the non-uniformly shaped fingerprint detection module to make direct contact with the finger of a user. The non-uniformly shaped fingerprint detection module can include a rectangular shaped fingerprint detection module with a first number of sensor pixels in one dimension and a second number of sensing electrodes larger than the first number in another dimension. The mobile device can include a protective cover disposed over the transparent top cover, the touch panel and the non-uniformly shaped fingerprint detection module to prevent direct contact between the finger of the user and the non-uniformly shaped fingerprint detection module. The non-uniformly shaped fingerprint detection module can include fingerprint sensing circuitry; and an array of sensing electrodes to detect the contact from the finger of the user to activate the non-uniformly shaped fingerprint detection module to capture the image of the finger of the user. The sensing circuitry can include more columns of pixelated sensing elements than rows of pixelated sensing elements. The non-uniformly shaped fingerprint detection module can receive a signal indicating the fingerprint registration mode. The non-uniformly shaped fingerprint module can capture the image of the finger during the swipe motion by capturing partial images of the finger in sequence during the swipe motion to accumulate a substantially complete fingerprint image to store as the registered fingerprint profile of an authorized user. The non-uniformly shaped fingerprint module can analyze the partial images of the finger captured during the swipe motion to determine whether a sufficient portion of the finger was captured to qualify as the registered fingerprint profile of an authorized user.

Various examples of fingerprint detection modules and fingerprint sensor modules described in this patent document can be integrated with mobile devices (e.g., smartphones, tablets, laptops), computing devices (e.g., personal computers), and other electronic devices to perform fingerprint authentication processes on these devices.

DETAILED DESCRIPTION

Electronic devices equipped with fingerprint authentication mechanisms may be hacked by malicious individuals who can obtain the authorized user's fingerprint, and copy the stolen fingerprint pattern on a carrier object that resembles a human finger, which can then be used to unlock the targeted device. Hence, the fingerprint pattern, although a unique biometric identifier, may not be by itself a completely reliable or secure identification. The techniques, devices and systems described in this document improve upon the fingerprint authentication technology used in existing electronic devices to potentially prevent a stolen fingerprint from being used to gain access to the targeted device.

Embodiments described in this document provide devices, systems, and techniques that implement various fingerprint detection modules for human fingerprint detection and authentication. Moreover, embodiments described in this document provide devices, systems, and techniques that implement various fingerprint detection modules including an optical sensing unit to determine if a detected object is human. Specifically, the technology disclosed in this document uses an additional measurement obtained from a person to combine with the person's fingerprint pattern as a combination authentication method to identify whether the authorized person is accessing the device.

The disclosed technology uses probe light at two or more different probe light wavelengths where the human skin provides different optical responses at the two or more different wavelengths. Measurements of such optical responses at the two or more different wavelengths are used to combine with the positive identification of the person's fingerprint pattern to authenticate the access. This additional layer of authentication can improve the level of authentication and the security that may not be possible by using the fingerprint pattern alone. In the specific examples described below, the two or more different probe light wavelengths may be selected so that reflectance or absorption of the person's skins due to presence of the blood in the skin and the oxygen level in the blood to cause different optical responses in the reflected light or transmitted light at the selected two or more different wavelengths. In implementation, the device can include two sensor devices: (1) a fingerprint pattern recognition sensor and (2) an optical detection module for producing probe light of two or more different wavelengths and for measuring the reflectance or transmission of the probe light of the finger to measure the optical responses of the finger at the two or more different wavelengths. The measurements from the two sensor devices are combined to authenticate a person for accessing the device. In implementations, those two sensor devices can be integrated into a fingerprint ID module located on a surface of a device to enable a user to input the user's fingerprint when accessing the device. The appearance of such a fingerprint ID module may be similar to other fingerprint ID modules where only fingerprint patterns are detected and processed but the additional optical detection module based the measurements of probe light of two or more different wavelengths provides a unique added security and accuracy in granting proper user access to the device.

FIG. 1Ashows a schematic of a cross-sectional view of a fingerprint detection module100(finger is not included) in accordance with some embodiments described herein. As shown inFIG. 1A, fingerprint detection module100includes a substrate carrier102and a fingerprint sensor detector chip104affixed on top of substrate carrier102. Fingerprint sensor detector chip104can use capacitive sensing to collect fingerprint data and detect fingerprints. However, fingerprint sensor detector chip104can also be configured to collect fingerprint data and detect fingerprints by non-capacitive means. Fingerprint detection module100also includes a protective cover106which is placed over fingerprint sensor detector chip104to protect fingerprint sensor detector chip104and can also serve as a dielectric spacer. Protective cover106may be made out of high dielectric-constant material, such as ceramic, sapphire, zirconia, among others. Protective cover106may also have a hard coating, such as diamond like carbon. Note that in the embodiment ofFIG. 1A, the edges of protective cover106extends beyond the edges of fingerprint sensor detector chip104in all directions.

Fingerprint detection module100additional includes a sensing or signal electrode such as a metal ring to detect a contact from a human finger or an object. The metal ring108is placed on substrate carrier102and around protective cover106, which protects the edge of protective cover106in addition to serving as sensing or signal electrode. Note also that a finger110(not part of fingerprint detection module100) can make contact with metal ring108when finger110is pressed on fingerprint detection module100for fingerprint detection.

FIG. 1Bis a schematic showing a cross-sectional view of an exemplary reduced size fingerprint detection module120shaped in a strip. The reduced size fingerprint detection module120shaped in a strip is substantially similar to the fingerprint detection module100except the overall size or form factor of the reduced size fingerprint detection module120is smaller. The shape of the reduced size fingerprint detection module120is smaller, shorter or narrower in one (e.g., vertical) dimension to minimize or reduce real estate taken up by the reduced size fingerprint detection module120shaped in a strip on a mobile device, such as a smartphone. The reduced size fingerprint detection module120shaped in a strip includes a substrate carrier122; a fingerprint sensor detector chip124affixed on top of substrate carrier122; a protective cover126placed over fingerprint sensor detector chip124; and a sensing or signal electrode such as a metal ring128to detect a contact from a human finger or an object.

In one example, a width of the reduced size fingerprint detection module120shaped in a strip is larger than a height of the reduced size fingerprint detection module120shaped in a strip. In another example, the height can be larger than the width of the reduced size fingerprint detection module120shaped in a strip. The proportion of the width verses the height can depend at least on the orientation of the reduced size fingerprint detection module120on a mobile device. Consistent with the reduced size of the reduced size fingerprint detection module120shaped in a strip, the associated substrate carrier122, fingerprint sensor detector chip, protective cover106and the metal ring108are also reduced in size. In addition to the reduced size, the form factor and/or shape of each components in the reduced size fingerprint detection module120is modified to match the overall form factor and size of the reduced size fingerprint detection module having a non-uniform shape, e.g., a rectangular shape where he width is larger than the height. In order words, the number of sensor pixels in a first dimension of the fingerprint detection module is larger than a second dimension that is substantially perpendicular to the first dimension.

To accommodate the reduced form factor of the reduced size fingerprint detection module120, a hybrid mode of operation can be implemented to cover fingerprint registration and fingerprint recognition. The hybrid mode of operation includes a swipe motion of the finger110as shown by arrow130to register an authorized user's fingerprint image and store the registered fingerprint image as a fingerprint profile of the authorized user and associate the registered fingerprint profile to the authorized user. The swipe motion to register the fingerprint image of the authorized user allows a substantially complete image of the authorized user's fingerprint to be acquired. The authorized user can be instructed during the registration portion of the hybrid operation mode to swipe the user's finger at a predetermined manner such as ‘top-down’, ‘down-up’ or “side-to-side” depending on the orientation of the reduced size fingerprint detection module120with respect to the authorized user and/or with respect to the mobile device on which the reduced size fingerprint detection module120is disposed. In addition, the authorized user may be instructed during the registration portion of the hybrid operation mode to swipe the user's finger at a constant speed, at a predetermined speed, etc. The instructions given to the authorized user regarding the manner of registering the authorized user's fingerprint image can be in the form of written text on a display screen of the mobile device, a voice recording, a sound tone, or any combination of the visual and audio instructions and indicators.

Once the fingerprint of the authorized user is registered, the same authorized user can be given access to the mobile device during the fingerprint recognition portion of the hybrid mode of operation. To access the mobile device during the fingerprint recognition portion of the hybrid mode of operation, the authorized user touches any portion of the authorized user's finger (or thumb) print on the reduced size fingerprint detection module120. A swipe motion used during the registration portion is not needed during the recognition phase of the hybrid mode of operation. Although only a small portion of the authorized user's fingerprint is captured by the reduced size fingerprint detection module120due to the reduced, the captured small portion of the authorized user's fingerprint is enough to perform a matching operation against the previously registered and stored fingerprint profile associated with the authorized user. The matching process includes matching the captured fingerprint image of the portion of the authorized user fingerprint with the registered substantially full image of the authorized user's fingerprint. The image matching process can include pixel-by-pixel matching operation and can include manipulating the two images including rotating, filtering, image enhancement(s), interpolation, compression, etc. to compare the two images. The captured fingerprint image can be determined to match the registered fingerprint profile of the authorized user based on a result of the matching process satisfying a predetermined threshold. For example, the predetermined threshold can be associated with statistically significant correlation between the two images.

FIG. 1Cis a process flow diagram showing an exemplary process140for performing a fingerprint registration mode of a hybrid mode of operation. The hybrid mode of operation140includes receiving a signal indicating activation or initiation of the registration mode of operation (142). For example, the received signal indicating activation of initiation of the registration mode can include a user selection (from a list of user selectable functions on a menu, for example) to initiate or activate fingerprint registration. The fingerprint registration usually occurs soon after the user purchases the mobile device to register the user as an authorized user or anytime when desiring to add or remove an authorized user to the mobile device. Until the fingerprint registration is completed for at least one authorized user, the fingerprint recognition security feature may not be active.

Responsive to the signal indicating initiation or activation of the fingerprint registration mode (142), an instruction is provided to the user describing a manner in which the user's finger or thumb should contact or touch the reduced size fingerprint detection module (144). The instruction provided can include text displayed on a display module of the mobile device, audio instructions, illustrative instructions displayed on the display module (including one or sequence of images and/or video clips), or any other visual and/or audio instructions. To accommodate the reduced size form factor and/or size of the reduced fingerprint detection module (144), a swipe motion can be suggested in the instruction. The swipe motion can include “up-down”, “down-up”, “side-to-side”, “diagonal-up”, “diagonal-down”, etc. that correspond to the orientation and/or position of the reduced size fingerprint detection module120with respect to the rest of the mobile device on which the reduced size fingerprint detection module120is located. For example, when a width of the reduced size fingerprint detection module120is larger than a height of the reduced size fingerprint detection module, an “up-down” or a “down-up” swipe motion can be used.

Responsive to the user making a swipe motion on the reduced size fingerprint detection module, an image of the user's fingerprint is acquired or captured (146). The acquired or captured image of the user's fingerprint is compared against a template or default human fingerprint to determine whether a substantially complete or full fingerprint image was captured (148). When determined that a substantially complete or full image of the user's fingerprint has been captured, the captured substantially complete or full image of the user's fingerprint is stored as a fingerprint profile of the user and marked as an authorized user's fingerprint profile (150).

Information such as name, phone number, address, age, etc. can be received from the user to identify the user as a unique authorized user and the received information can be included in the fingerprint profile or otherwise associated with the fingerprint profile (152).

FIG. 1Dshows a process flow diagram of a process160for performing a fingerprint recognition mode of a hybrid mode of operation. The hybrid mode of operation140includes receiving a signal indicating activation or initiation of the fingerprint recognition mode of operation (162). For example, the received signal indicating activation of initiation of the registration mode can include a user touching or contacting the reduced size fingerprint detection module of a locked mobile device to initiate or activate fingerprint recognition. The user touching or contacting the reduced size fingerprint detection module can initiate a signal from the sensing electrode (e.g., metal ring128) indicating the touch or contact.

Responsive to the signal indicating initiation or activation of the fingerprint recognition mode (162), an image of at least a portion of an object touching the reduced size fingerprint detection module is captured (164). The acquired or captured image of the user's fingerprint is compared against a template or default human fingerprint to determine whether the captured image is of a human fingerprint (166). When determined that the captured image of the object is of a human fingerprint (168), the captured image is compared with a registered fingerprint profile of an authorized user. When determined that the captured image matches the registered fingerprint profile of an authorized user, the user is granted access to the mobile device as an authorized user (170). When determined that the captured image does not match the registered fingerprint profile of an authorized user, the user is denied access to the mobile device as an authorized user (172).

FIG. 2Ashows a schematic of an exemplary fingerprint sensor detector chip200in accordance with some embodiments described herein. Note that fingerprint sensor detector chip200(or “sensor chip200”) may be used as sensor chip104in fingerprint detection module100or in combination with other types of fingerprint detection modules described below.

As shown inFIG. 2A, fingerprint sensor detector chip200comprises a pixelated sensing element array202which occupies a significant portion of the sensor chip. Each sensing element in pixelated sensing element array202may be a CMOS capacitive sensor or other types of sensors capable of sensing fingerprint features. Fingerprint sensor detector can also include a signal processing unit204for processing signals received from pixelated sensing element array202, and a connection unit206coupled to signal processing unit204. Connection unit206may include multiple electrodes which can be connected to external circuitry through wire-bonding, bump bonding or other connection means. Connection unit206may be situated along an edge of sensor chip200for the convenience of interfacing with other components of a fingerprint detection module.

Note that sensor chip200also includes one or more photodetection elements208, which may be located at one or more sections of sensor chip200. Photodetection elements208can include, but are not limited to CMOS photodetectors, charge-coupled devices (CCD) photodetectors, light-emitting diode (LED) photodetectors, photoresistors, photovoltaic photodetectors, and photodiodes. In the embodiment shown, there are two photodetection elements located along one edge section of the sensor chip. In one embodiment, there can be just a single photodetection element or more than two photodetection elements. The multiple photodetection elements may be located at different edge sections of the silicon chip instead of all on the same side of the chip. Note that whileFIG. 2Ashows that photodetection elements208are integrated with pixelated sensing element array202on the same chip, other embodiments can have the photodetection elements off the sensor chip on a different area of the fingerprint sensor module.

FIG. 2Bshows a schematic of an exemplary reduced size fingerprint sensor detector chip210. The exemplary reduced size fingerprint sensor detector chip210(or “reduced size sensor chip210”) can be used as sensor chip124in the fingerprint detection module120or in combination with other types of fingerprint detection modules described below. The reduced size sensor chip210is substantially similar to the sensor chip200except for a reduced size and different shape of the reduced size sensor chip210. As shown inFIG. 2B, fingerprint sensor detector chip200includes a pixelated sensing element array212which occupies a significant portion of the sensor chip. Each sensing element in pixelated sensing element array212can be a CMOS capacitive sensor or other types of sensors capable of sensing fingerprint features. Fingerprint sensor detector can also include a signal processing unit214for processing signals received from pixelated sensing element array212, and a connection unit216coupled to signal processing unit214. Connection unit216may include multiple electrodes which can be connected to external circuitry through wire-bonding, bump bonding or other connection means. Connection unit216may be situated along an edge of sensor chip210for the convenience of interfacing with other components of a fingerprint detection module.

The sensor chip210also includes one or more photodetection elements218, which may be located at one or more sections of sensor chip210. Photodetection elements218can include, but are not limited to CMOS photodetectors, charge-coupled devices (CCD) photodetectors, light-emitting diode (LED) photodetectors, photoresistors, photovoltaic photodetectors, and photodiodes. in the embodiment shown, there are two photodetection elements located along one edge section of the sensor chip. In one embodiment, there can be just a single photodetection element or more than two photodetection elements. The multiple photodetection elements may be located at different edge sections of the silicon chip instead of all on the same side of the chip. WhileFIG. 2Bshows that photodetection elements218are integrated with pixelated sensing element array212on the same chip, other embodiments can have the photodetection elements off the sensor chip on a different area of the fingerprint sensor module.

The reduced size sensor chip210can be shaped as a reduced size rectangle with a width larger than a height of the sensor chip210. Exemplary sizes for the reduced size sensor chip210can include 24×88, 32×88, 56×88 pixelated sensing elements compared to the more square shaped (e.g., 64×64 pixelated sensing elements) of the sensor ship200. The size or number of pixelated sensing elements can be reduced to obtain substantially a complete of full fingerprint image sufficient to register a user as an authorized user using a swipe motion, and to obtain sufficient portion of the user's fingerprint image from a touch or tap contact during the fingerprint recognition mode to perform a comparison against the registered fingerprint profile image. The swipe motion of the user's finger can be used to obtain an image of the user's fingerprint by using a minimum of three lines from the images captured from the pixelated sensing element array212to identify the different of delta between the three lines. In addition, the speed of the swipe motion can be detected from the difference between the three lines.

FIG. 3Ashows a perspective and cross-sectional view of a fingerprint detection module300which includes an optical sensing mechanism for determining if a detected object is human in accordance with some embodiments described herein. Similarly to fingerprint detection module100, fingerprint detection module300includes a substrate carrier302, a fingerprint sensor detector chip304, a protective cover306, and a metal ring308. Fingerprint sensor detector chip304can be fingerprint sensor detector chip200to include one or more photodetection elements. In some embodiments however, the one or more photodetection elements are located off of sensor chip200and on another area of substrate carrier302cavity protective cover306. The protective cover can be made of transparent materials, such as sapphire or zirconia. If there are cosmetic coloring applied to protective cover306, a transparent window may be used on protective cover306to allow light to go through. Note that in this embodiment, protective cover306covers the entire surfaces of sensor chip304.

Fingerprint detection module300also includes one or more light emitting sources310which can be placed within a cavity312of metal ring308. Light emitting sources310can include one or more light emitting diode (LED) chips, one or more diode lasers, or one or more other miniature light emitting devices. An exemplary LED chip in such applications can have an area of ˜200 μm×200 μm and a thickness of ˜200 μm. In the embodiment shown, cavity312has a ring structure which is formed around the underside of metal ring308. However, cavity312in metal ring308can have many other configurations, for example, to only present around the locations of light emitting sources310.

Light emitting sources310can be configured to emit detection light of desirable wavelengths in response to a human finger or an object making contact with fingerprint detection module300. For example, metal ring308can serve as a sensing electrode to detect the contact from a human finger or an object. Light emitting sources310can emit light through one or more light emitting windows which cut through metal ring308to connect to cavity312. InFIG. 3A, a light emitting window314is located directly above one of the light emitting sources310inside cavity312. In some embodiments, light emitting sources310include a modulated light source.

FIG. 3Bprovides another perspective and cross-sectional view of fingerprint detection module300in accordance with some embodiments described herein.FIG. 3Cprovides a perspective view of entire fingerprint detection module300in accordance with some embodiments described herein.

FIG. 3Dshows a cross-sectional view of an exemplary reduced size fingerprint detection module320which includes an optical sensing mechanism for determining whether a captured image of an object making contact matches a registered fingerprint profile of an authorized user. The reduced size fingerprint detection module320is substantially similar to the fingerprint detection module300except for a reduced size and a different shape of the reduced size fingerprint detection module320. As described above with respect to the reduced size fingerprint detection module120, the size and shape of the reduced size fingerprint detection module320is smaller, shorter or narrower in one (e.g., vertical) dimension to minimize or reduce real estate taken up by the reduced size fingerprint detection module320shaped in a strip on a mobile device, such as a smartphone. In one example, a width of the reduced size fingerprint detection module320is larger than a height of the reduced size fingerprint detection module320.

To accommodate the smaller, shorter or narrower form factor and/or size of the reduced fingerprint detection module320, a swipe motion can be suggested in the instruction. The swipe motion can include “up-down”, “down-up”, “side-to-side”, “diagonal-up”, “diagonal-down”, etc. that correspond to the orientation and/or position of the reduced size fingerprint detection module320with respect to the rest of the mobile device on which the reduced size fingerprint detection module320is located. For example, when a width of the reduced size fingerprint detection module320is larger than a height of the reduced size fingerprint detection module, an “up-down” or a “down-up” swipe motion can be used.

Similarly to the reduced size fingerprint detection module120, the reduced size fingerprint detection module320includes a substrate carrier322, a fingerprint sensor detector chip324, a protective cover326, and a sensing electrode such as a metal ring328. Reduced size fingerprint sensor detector chip324can be substantially similar to reduced size fingerprint sensor detector chip210to include one or more photodetection elements. In some embodiments however, the one or more photodetection elements are located off of sensor chip324and on another area of substrate carrier cavity protective cover326. The protective cover326can be made of transparent materials, such as sapphire or zirconia. When a cosmetic coloring is applied to protective cover326, a transparent window may be used on protective cover326to allow light to go through. The protective cover326can cover the entire surface of the reduced size sensor chip324.

Reduced size fingerprint detection module320also includes one or more light emitting sources330which can be placed within a cavity332of a sensing electrode such as a metal ring328. Light emitting sources330can include one or more light emitting diode (LED) chips, one or more diode lasers, or one or more other miniature light emitting devices. An exemplary LED chip in such applications can have an area of ˜200 μm×200 μm and a thickness of ˜200 μm. In the embodiment shown, cavity332has a ring structure which is formed around the underside of metal ring308. However, cavity332in metal ring328can have many other configurations, for example, to only present around the locations of light emitting sources330.

Light emitting sources310can be configured to emit detection light of desirable wavelengths in response to a human finger or an object making contact with the reduced size fingerprint detection module320. For example, metal ring328can serve as a sensing electrode to detect the contact from a human finger or an object. Light emitting sources330can emit light through one or more light emitting windows which cut through metal ring328to connect to cavity332. InFIG. 3D, a light emitting window334is located directly above one of the light emitting sources330inside cavity332. In some embodiments, light emitting sources330include a modulated light source.

FIG. 3Dshows a top-down perspective view of the reduced size fingerprint detection module320.

FIG. 4Aillustrates the concept of using a fingerprint detection module400(which is substantially similar to fingerprint detection module300) to detect and determine if a detected object is human in accordance with some embodiments described herein. WhileFIG. 4Ais described in the context of fingerprint detection module400, the techniques described herein are general applicable to many variations of fingerprint detection module400, some of which will be described later in the disclosure.

As mentioned above, fingerprint detection module400includes substrate carrier402, protective layer406, metal ring408and sensor chip404, which may include a capacitive sense array for sensing a fingerprint's ridge and valley patterns. Fingerprint detection module400includes light emitting sources410which reside within a cavity under metal ring408. In some implementations, light emitting sources410can emit at least two different wavelengths through light emitting window414of metal ring408. Fingerprint detection module400also includes one or more photodetectors416which can either be integrated on sensor chip404or separately placed on substrate carrier402. In the embodiment shown, photodetectors416are located on an edge of sensor chip404.

In some implementations, when an object420(not part of fingerprint detection module400) makes contact of fingerprint detection module400, light emitting sources410emits detection light through light emitting window414. The detection light is reflected off object420and the reflected light can be received and measured by photodetectors416. In particular implementations, two wavelengths of detection light are emitted by light emitting sources410. For example, one wavelength can be 660 nm and the other wavelength is one of 905 nm, 910 nm or 940 nm. In another embodiment, the two wavelengths are 590 nm and 805 nm. In yet another embodiments, the two wavelengths are 520 nm and 575 nm.

FIG. 4Bshows a concept of using a reduced size fingerprint detection module430(which is substantially similar to fingerprint detection module320) to determine whether an image captured from an object making contact with the reduced size fingerprint detection module430matches a registered fingerprint profile of an authorized user. For example,FIG. 4Bshows a user operating in the fingerprint recognition mode to capture an image of at least a portion of the user's fingerprint and comparing the captured image against the registered fingerprint profile of an authorized user to determine whether the user is an authorized user.

The reduced size fingerprint detection module430is substantially similar to the fingerprint detection module400except for a reduced size and a differing shape of the reduced size fingerprint detection module430. As described above with respect to the reduced size fingerprint detection modules120and320, the size and shape of the reduced size fingerprint detection module430is smaller, shorter, narrower in one (e.g., vertical) dimension to minimize or reduce real estate taken up by the reduced size fingerprint detection module430on a mobile device, such as a smartphone. In one example, a width of the reduced size fingerprint detection module430is larger than a height of the reduced size fingerprint detection module430shaped in a strip.

To accommodate the smaller, shorter, narrower form factor and/or size of the reduced fingerprint detection module430, a swipe motion can be suggested in the instruction. The swipe motion can include “up-down”, “down-up”, “side-to-side”, “diagonal-up”, “diagonal-down”, etc. that correspond to the orientation and/or position of the reduced size fingerprint detection module430with respect to the rest of the mobile device on which the reduced size fingerprint detection module430is located. For example, when a width of the reduced size fingerprint detection module430is larger than a height of the reduced size fingerprint detection module, a “up-down” or a “down-up” swipe motion can be used.

The reduced size fingerprint detection module430includes a substrate carrier432, a protective layer436, a sensing electrode such as a metal ring438, and a sensor chip434, which may include a capacitive sense array for sensing a fingerprint's ridge and valley patterns. Fingerprint detection module430includes light emitting sources440which reside within a cavity under metal ring438. In some implementations, light emitting sources440can emit at least two different wavelengths through light emitting window444of metal ring438. The reduced size fingerprint detection module430also includes one or more photodetectors446which can either be integrated on sensor chip434or separately placed on substrate carrier432. In the embodiment shown, photodetectors446are located on an edge of sensor chip434.

In some implementations, when an object420(not part of fingerprint detection module400) makes contact with the reduced size fingerprint detection module430, light emitting sources440emits detection light through light emitting window444. The detection light is reflected off object420and the reflected light can be received and measured by photodetectors446. Two wavelengths of detection light can be emitted by light emitting sources440. For example, one wavelength can be 660 nm and the other wavelength is one of 905 nm, 910 nm or 940 nm. In another embodiments, the two wavelengths are 590 nm and 805 nm. In yet another embodiments, the two wavelengths are 520 nm and 575 nm.

FIG. 5Ashows a data plot of normalized human skin reflectance (in %) as a function of the wavelength of the light source in accordance with some embodiments described herein. Note that human skin has different reflectance in response to different wavelengths and this relationship can be measured. As a result, the photodetector signals corresponding to the reflected light from the two selected wavelengths can be significantly different. In some implementations, photodetectors416can be configured to measure the reflected light from both wavelengths. The ratio of the two measurements can then be computed and compared to a standard or calibrated value for human finger/skin to determine if object420is human finger or not. The computation, comparison, and determination operations can be performed by an on chip signal processing unit such as signal processing unit204shown inFIG. 2.

FIG. 5Bshows a data plot of human blood light absorption property (in extinction coefficient) as a function of the wavelength of the light source in accordance with some embodiments described herein. Note that human blood has different absorptions in response to different wavelengths. Moreover, for blood Hemoglobin lack of Oxygen (referred to as “Hb state”) and bound with Oxygen (referred to as “HbO2 state”), the absorption behaviors are also significantly different. As a result, the photodetector signals corresponding to the reflected light from the two selected wavelengths can be significantly different, and the photodetector signals corresponding to the reflected light from the same wavelength under Hb or HbO2 state can also be significantly different. In some implementations, photodetectors416can be configured to measure the transmitted light through object420for both wavelengths. The ratio of the two measurements can then be computed and compared to a standard or calibrated value for human blood absorption to determine if object420is human finger or not. The computation, comparison, and determination operations can be performed by an on-chip signal processing unit such as signal processing unit204shown inFIG. 2.

Photodetectors416can also be configured to measure the transmitted light through object420for one or both wavelengths under both Hb state and HbO2 state. The ratio of the two measurements at two different wavelengths in each of the two states can then be computed and compared to standard or calibrated values for human blood absorption to determine if object420is human finger or not. The computation, comparison, and determination operations can be performed by an on-chip signal processing unit such as signal processing unit204shown inFIG. 2.

The above measurements inFIG. 5A or 5Bor both at the two different optical wavelengths can also be used to measure the person's heartbeat based on the oxygen level in the blood due to pumping by the heart. The two different wavelengths can be at the red spectral range and the infrared spectral range, respectively. The heartbeat measurement is used in some pulse oximeter devices or heart rate monitors based on measurements of the saturated level of oxygen in the blood. The relative absorption of red (absorbed by oxygenated blood) and infrared (absorbed by deoxygenated blood) light correlates to arterial blood oxygen saturations. Measurements of relative light absorption are made and are processed to generate the heart beat rate. This heart beat measurement provides another check on whether the person is present when the fingerprint pattern is presented to the target device that is to be accessed.

As mentioned above, a touch sensor within the fingerprint detection module, such as metal ring408in fingerprint detection module400can be used to detect the initial contact of an object, such as a user's finger. In one embodiment, the metal ring may be part of circuitry for initial contact detection and module activation. In some embodiments, the fingerprint detection module can be in a standby mode (i.e., power saving mode) before the detection of a new contact. Upon detecting a new contact, the metal ring circuitry then activates the main circuit of the fingerprint detection module. When a current fingerprint detection and authentication process is complete, the main circuitry of the fingerprint detection module can be turned off or deactivated and the fingerprint detection module returns to the standby mode while the metal ring circuitry remains active and ready for next contact.

FIG. 6Ais a schematic showing a cross sectional view of an exemplary mobile device600integrated with a touch screen assembly and a fingerprint detection module in accordance with some embodiments described herein, As shown inFIG. 6A, mobile device600(e.g., a smartphone) includes a fingerprint detection module602having a touch sensor such as a metal ring604positioned to be substantially level with a surface of mobile device600parallel with a surface of top cover glass606exposed to the user. The touch sensor can be implemented using any conductive material, such as any number of known metals. In addition, the shape of the touch sensor can vary based on the shape and design of the fingerprint detection module. The touch sensor can be designed to border at or near the outline of the fingerprint detection module so as to substantially surround the portion of the fingerprint detection module exposed to a user. For example, for a fingerprint detection module in a round shape, a metal ring can be used as the touch sensor. For a fingerprint detection module shaped as a rectangle, the touch sensor can be formed in the shape of a rectangular frame. The top cover glass606of mobile device600includes an opening to allow fingerprint detection module602to fit through and be exposed on the surface. In addition, top glass606can be implemented using transparent materials other than glass including various crystalline structures, such as sapphire that provides the mobile device600with protection while allowing at least visible light to pass through. Mobile device600also includes a touch panel608and an LCD display module610positioned underneath capacitive touch panel608. Touch panel608can be implemented using various touch technologies including a capacitive touch sensor, an inductive touch sensor, and other touch sensors. The touch panel and the LCD display module610together form the touch screen assembly. When mobile device600is locked, LCD display module610is turned off and a main processor of mobile device600and fingerprint detection module602are in standby mode. To unlock mobile device600, a user can make contact with the fingerprint detection module602with the user's finger, for example. A touch sensor such as metal ring604and associated circuitry communicatively coupled to the metal ring604can be used to detect a contact from an object612with the fingerprint detection module602. The touch sensor and associated circuitry can be used to activate fingerprint detection module602responsive to a light contact, without additional user input through a mechanical switch, such as actuating a physical button.

FIG. 6Bis a schematic showing a cross sectional view of another exemplary mobile device620integrated with a touch screen assembly and a fingerprint detection module in accordance with some embodiments described herein. Similar to mobile device600inFIG. 6A, mobile device620includes a fingerprint detection module622having a touch sensor, such as a metal ring624. However, different from mobile device600, the top cover glass626of mobile device620does not have an opening to expose the top surface (e.g., the surface exposed to the user) of fingerprint detection module622. Instead, fingerprint detection module622is positioned underneath top cover glass626and is designed to sense a fingerprint of a finger without being directly in contact with the finger632.

In the embodiment ofFIG. 6B, top cover glass626protects touch panel628and LCD display module630of the touch screen assembly and other areas of a top surface of mobile device620substantially parallel with the top cover glass626beyond the touch sensitive area associated with the touch panel, including a location above fingerprint detection module622. Touch panel628is embedded within a support glass634underneath top cover glass626. Top cover glass626and support glass634can be implemented using materials similar to top cover glass606. Support glass634includes an opening to allow fingerprint detection module622to pass through and be placed under the top cover glass626. The location of the opening in support glass634may be closer to one end of support glass634, similar to the relative location of the opening in top cover glass606inFIG. 6A. The fingerprint detection module622in this design can sense a contact from a fingerprint of a finger632with a top surface (e.g., the surface exposed to the user) of the hardened top cover glass626without having an object such as the finger632being in direct contact with a surface on the fingerprint detection module622. This allows top cover glass626to fully cover both the touch screen assembly and the fingerprint sensor under a spatially contiguous protective surface without an opening.

In one embodiment, top cover glass626and support glass634are bonded together to form an overall cover glass structure that is significantly thicker and mechanically stronger than each of top cover glass626and support glass634individually. The two glass layers may be bonded with a thin adhesive layer, such as an epoxy adhesive layer. The overall thickness of the combined structure may be comparable to top cover glass606inFIG. 6A. Fingerprint detection module622which is positioned within the opening of support glass634may be directly attached underneath top cover glass626.

In everyday uses when a user is holding or carrying mobile device600or mobile device620(e.g., in a pocket close to the body), unintended and incidental contacts on metal ring604or an surface area directly above metal ring624are common and can be difficult to avoid. Activation of fingerprint detection module602or622and/or the main processor of mobile device600or620from a standby mode due to unintended contacts with the touch sensor can negatively impact power consumption of a mobile device. Devices, systems, and techniques described in various embodiments of this document can potentially enable light contact activation of fingerprint detection module602or622while preventing unintended contacts from activating the same fingerprint detection module602or622and/or mobile device600or620from a standby mode.

FIG. 6Cis a schematic showing a cross sectional view of an exemplary mobile device640integrated with a touch screen assembly and a reduced size fingerprint detection module642shaped in a strip. The reduced size fingerprint detection module642is substantially similar to the fingerprint detection module640inFIG. 6Aexcept for the reduced size and a differing shape of the reduced size fingerprint detection module642.

As described above with respect to the reduced size fingerprint detection modules120,320and430, the size and shape of the reduced size fingerprint detection module642is smaller, shorter, narrower in one (e.g., vertical) dimension to minimize or reduce real estate taken up by the reduced size fingerprint detection module642on the mobile device640, such as a smartphone. In one example, a width of the reduced size fingerprint detection module642is larger than a height of the reduced size fingerprint detection module642shaped in a strip.

To accommodate the smaller, shorter, narrower form factor and/or size of the reduced fingerprint detection module642, a swipe motion can be suggested in the instruction. The swipe motion can include “up-down”, “down-up”, “side-to-side”, “diagonal-up”, “diagonal-down”, etc. that correspond to the orientation and/or position of the reduced size fingerprint detection module642with respect to the rest of the mobile device on which the reduced size fingerprint detection module642is located. For example, when a width of the reduced size fingerprint detection module642is larger than a height of the reduced size fingerprint detection module, a “up-down” or a “down-up” swipe motion can be used. When the height is larger than the width, a “side-to-side” motion can be used.

The mobile device640(e.g., a smartphone) includes a fingerprint detection module642having a touch sensor or sensor electrode such as a metal ring644positioned to be substantially level with a surface of mobile device640parallel with a surface of top cover glass646exposed to the user. The touch sensor or sensor electrode can be implemented using any conductive material, such as any number of known metals. In addition, the shape of the touch sensor can vary based on the shape and design of the fingerprint detection module. The touch sensor can be designed to border at or near the outline of the fingerprint detection module so as to substantially surround the portion of the fingerprint detection module exposed to a user. For example, for a fingerprint detection module in a round shape, a metal ring can be used as the touch sensor. For a fingerprint detection module shaped as a rectangle, the touch sensor can be formed in the shape of a rectangular frame. The top cover glass646of mobile device640includes an opening to allow fingerprint detection module642to fit through and be exposed on the surface. In addition, top glass646can be implemented using transparent materials other than glass including various crystalline structures, such as sapphire that provides the mobile device640with protection while allowing at least visible light to pass through. Mobile device640also includes a touch panel648and an LCD display module650positioned underneath capacitive touch panel648. Touch panel648can be implemented using various touch technologies including a capacitive touch sensor, an inductive touch sensor, and other touch sensors. The touch panel and the LCD display module650together form the touch screen assembly. When mobile device640is locked, LCD display module650is turned off and a main processor of mobile device640and fingerprint detection module642are in standby mode. To unlock mobile device640, a user can make contact with the fingerprint detection module642with the user's finger, for example. A touch sensor or sensor electrode such as metal ring644and associated circuitry communicatively coupled to the metal ring644can be used to detect a contact from an object652with the fingerprint detection module642. The touch sensor and associated circuitry can be used to activate fingerprint detection module642responsive to a light contact, without additional user input through a mechanical switch, such as actuating a physical button.

FIG. 6Dis a schematic showing a cross sectional view of another exemplary mobile device660integrated with a touch screen assembly and a fingerprint detection module in accordance with some embodiments described herein. Similar to mobile device640inFIG. 6C, mobile device660includes a reduced fingerprint detection module662substantially similar to reduced fingerprint detection module642having a touch sensor or a sensor electrode, such as a metal ring664. However, different from mobile device640, the top cover glass666of mobile device660does not have an opening to expose the top surface (e.g., the surface exposed to the user) of fingerprint detection module662. Instead, fingerprint detection module662is positioned underneath top cover glass666and is designed to sense a fingerprint of a finger without being directly in contact with the finger672.

In the embodiment ofFIG. 6D, top cover glass666protects touch panel668and LCD display module670of the touch screen assembly and other areas of a top surface of mobile device620substantially parallel with the top cover glass666beyond the touch sensitive area. associated with the touch panel, including a location above fingerprint detection module662. Touch panel668is embedded within a support glass674underneath top cover glass666. Top cover glass666and support glass674can be implemented using materials similar to top cover glass646. Support glass674includes an opening to allow fingerprint detection module662to pass through and be placed under the top cover glass666. The location of the opening in support glass674may be closer to one end of support glass674, similar to the relative location of the opening in top cover glass646inFIG. 6D. The fingerprint detection module662in this design can sense a contact from a fingerprint of a finger672with a top surface (e.g., the surface exposed to the user) of the hardened top cover glass666without having an object such as the finger672being in direct contact with a surface on the fingerprint detection module662. This allows top cover glass666to fully cover both the touch screen assembly and the fingerprint sensor under a spatially contiguous protective surface without an opening.

In one embodiment, top cover glass666and support glass674are bonded together to form an overall cover glass structure that is significantly thicker and mechanically stronger than each of top cover glass666and support glass674individually. The two glass layers may be bonded with a thin adhesive layer, such as an epoxy adhesive layer. The overall thickness of the combined structure may be comparable to top cover glass666inFIG. 6A. Fingerprint detection module662which is positioned within the opening of support glass674may be directly attached underneath top cover glass666.

In everyday uses when a user is holding or carrying mobile device640or mobile device660(e.g. in a pocket close to the body), unintended and incidental contacts on metal ring644or an surface area directly above metal ring664are common and can be difficult to avoid. Activation of fingerprint detection module642or652and/or the main processor of mobile device640or660from a standby mode due to unintended contacts with the touch sensor can negatively impact power consumption of a mobile device. Devices, systems, and techniques described in various embodiments of this document can potentially enable light contact activation of fingerprint detection module642or662while preventing unintended contacts from activating the same fingerprint detection module642or662and/or mobile device640or660from a standby mode.

FIG. 7Apresents a flowchart illustrating an exemplary process700of activating a fingerprint detection module from standby mode and using the fingerprint detection module to authenticate a user's request to gain access to a locked mobile device in accordance with some embodiments described herein. The exemplary process700ofFIG. 7Ais described with respect to fingerprint detection module400or430and mobile device600or620. A fingerprint detection module (e.g., fingerprint detection module400or430) in standby mode has a touch sensor enabled to continuously receive from the touch sensor a touch sensor signal (e.g., a metal ring signal from the metal ring touch sensor) indicating a contact from an object with the touch sensor (e.g., metal ring) and the fingerprint detection module (702). In one embodiment, the metal ring touch sensor (e.g., metal ring408in fingerprint detection module400or metal ring438in reduced size fingerprint detection module430) of the fingerprint detection module and associated touch sensing circuitry (which may be integrated with sensor chip404or reduced size sensor chip434) are used for the contact detection. For example, the associated touch sensing circuitry can generate a signal in response to an increase of capacitive load on the metal ring caused by an object, such as a finger, making contact with the metal ring. Note that light emitting sources within the fingerprint detection module are not enabled at this point. Until a metal ring signal is detected at702, the fingerprint detection module stays in standby mode waiting for the metal ring signal indicating a detected contact as shown inFIG. 7A.

Responsive to the fingerprint detection module receiving a metal ring signal from the touch sensor and associated touch sensing circuitry, the fingerprint detection module activates an optical detection module and turns on light emitting sources, such as LEDs within the fingerprint detection module to emit detection light of two selected wavelengths (704). The optical detection module includes one or more photodetectors within the fingerprint detection module (e.g., photodetector416in module400) to measure optical signals associated with the emitted detection light reflecting off of the contacting object and/or the emitted detection light passing through (i.e., transmitted light) the contacting object (706). The detection light passing through the contacting object can be used to determine a light absorption property of the contacting object. A signal processing module processes photodetector signals corresponding to the measured optical signals in two predetermined wavelengths. Based at least partially on the processed photodetector signals, the signal processing module determines whether the detected contact is from human skin by comparing computed signal ratios of the processed photodetector signals at two selected wavelengths with the characteristic values of the same parameters of human skin (708). In some implementations, the optical detection module is integrated with the fingerprint sensor chip.

When the determination at708is that the detected contact is not from human skin, the fingerprint detection module is switched back to the standby mode (702). For example, the detected contact could be based on a non-human-skin object making contact with the metal ring, such as human body touching the metal ring through clothing. In one implementation, returning to the standby mode also involves turning off the light emitting sources. However, when the determination at708is that the detected contact is from human skin, the fingerprint detection module activates the main fingerprint sensor and the associated circuitry in the fingerprint detection module, and begins obtaining fingerprint sensor data from the human skin (710).

The fingerprint detection module processes the obtained fingerprint sensor data to determine whether a human fingerprint is detected (712). This is performed prior to full fingerprint verification to distinguish a human fingerprint from another part of human skin, such as another part of a human hand, human arm, and human face, making contact with the fingerprint detection module. In some implementations, the initial determination of human fingerprint at712does not obtain and process the full fingerprint data in order to save power and processing time. For example, the fingerprint sensor measures one-directional (1D) human skin profile and associated detection circuitry determines whether the measured 1D skin profile substantially matches a human fingerprint. The detection circuitry associated with the fingerprint sensor can compare the measured 1D skin profile with a typically 1D fingerprint contour that includes a periodic ridge and valley pattern and determine whether the measured 1D skin profile resembles a human fingerprint. Moreover, the detection circuitry used to perform the initial determination of human fingerprint at712can be low power detection circuitry within the fingerprint detection module, for example, circuitry integrated with the sensor chip. As such, performing the initial determination of human fingerprint at712does not require the main processor (e.g., the application processor) of the mobile device, which can remain in standby mode until full fingerprint verification is needed. Using partial fingerprint data and low power circuitry can ensure low power consumption at710and712.

When the determination at712is that a human fingerprint is not detected from the human skin, the fingerprint detection module again is switched back to the standby mode at702. For example, the detected contact from human skin without a human fingerprint can be the result of a contact from a side of the user's hand, arm or face with the metal ring. In one implementation, returning to the standby mode of702also includes turning off the light emitting sources.

When the determination at712is that the detected contact is from a human fingerprint, the fingerprint detection module then obtains full fingerprint data with the fingerprint sensor and sends the obtained full fingerprint data to the main processing unit for processing (714), which may involve waking up the main processing unit from the standby mode. The full fingerprint sensor data is processed by the main processing unit to verify whether the obtained full fingerprint data match the stored fingerprint data of an authorized user of the mobile device. Based on the outcome of the verification, the main processing unit authorizes or denies user access to the locked mobile device (716). The fingerprint detection module is switched back to the standby mode at702if access is denied. Otherwise, if the access is granted, the fingerprint detection module is also switched back to the standby mode but does not return back to702.

FIG. 7Bpresents a flowchart illustrating an exemplary process701of authenticating user request to access a locked mobile device in a high security mode based on a combination of fingerprint detection and optical heartbeat detection. The process701illustrated inFIG. 7Bincludes a fingerprint detection process which is substantially similar to the process700ofFIG. 7Afrom (702) to (714). The full fingerprint sensor data obtained (714) is processed to verify whether the obtained fingerprint data match the stored fingerprint data of an authorized user of the locked mobile device (726). When no match is found, the user request to access the mobile device is denied and the fingerprint detection module is switched back to the standby mode (702). When a match is verified, the fingerprint detection module activates an optical detection module including the light emitting sources and the photodetectors to detect the presence of human heartbeat signals (728). Detecting the presence of human heartbeat signal can be performed with or without determining the actual heart beat rate. As described above, the two optical wavelengths emitted by the light emitting sources can be used to measure a user's heartbeat based on the oxygen level in the blood due to pumping of the heart. This heartbeat measurement offers an additional check on whether a live person is associated with the detected human fingerprint.

When the presence of a heartbeat signal is detected (730), the user request to access the locked mobile device is granted and the fingerprint detection module is switched back to a standby mode (732). Otherwise, the user request to access the locked mobile device is denied and the fingerprint detection module is switched back to the standby mode (702). Combining heartbeat detection with the fingerprint detection provides an added layer of security to the user authentication procedure.

FIG. 8presents a flowchart illustrating another exemplary process800of authenticating user request to access a locked mobile device in a high security mode based on a combination of fingerprint detection and optical heartbeat detection.

A fingerprint detection module in a standby mode can continuously monitors for a contact from an object with the fingerprint detection module (802). When the fingerprint detection module detects a contact from an object with the fingerprint detection module, the fingerprint detection module is used to determine whether the detected contact is from human skin (804). In absence of contact from human skin, the fingerprint detection module returns to standby mode and continues to monitor for another contact (802). When a contact from human skin is detected, the fingerprint detection module obtains data from the object making contact to determine whether the data from the object resembles human fingerprint (806). In absence of fingerprint detection, the fingerprint detection module returns to standby mode and continues to monitor for the next contact (802). When the detected contact is determined to be from human fingerprint, the main processing unit attempts to authenticate the obtained fingerprint data to determine whether the obtained fingerprint data match the stored fingerprint patterns of an authorized user of the mobile device (808). When the obtained fingerprint data does not match with the stored fingerprint pattern of the authorized user of the mobile device, the fingerprint detection module returns to standby mode and continues to monitor for the next contact (802). When the obtained fingerprint data match the stored fingerprint pattern of an authorized user of the mobile device, the fingerprint detection module determines whether the detected fingerprint of an authorized user of the mobile device is associated with a live human by detecting a presence of a heartbeat signal (810). When the presence of a heartbeat signal is detected, the user request to access the locked mobile device is granted. When the presence of a heartbeat is not detected, the user request to access the locked mobile device is denied and the fingerprint detection module returns to standby mode and continues to wait for the next contact (802). In various embodiments, the added verification of the heartbeat signal detection associated with the authorized user fingerprint detection at810can be implemented as an optional process and the user request to access the locked mobile device can be granted or denied based solely on the detection of an authorized user's fingerprint at808. In some implementations, the user authentication process800can directly obtain fingerprint data from the object making contact without one or both intermediate processes of identifying the detected contact as being from human skin (804) and determining whether fingerprints can be found on the identified human skin (806). In some other implementations, the heartbeat detection process (810) may be performed after detecting a contact from an object (802) but before determining whether fingerprint data of an authorized user can be detected on the human skin making contact with the touch sensor of the fingerprint detector (808).

FIG. 9Aillustrates an exemplary fingerprint detection module900as a variation of fingerprint detection module400for determining whether a detected contact from an object is from human skin in accordance with some embodiments described herein.

Similarly to fingerprint detection module400, fingerprint detection module900includes substrate carrier902, protective cover906, touch sensor such as a metal ring908and sensor chip904, which may include a capacitive sense array for sensing a fingerprint's ridge and valley patterns. Also, fingerprint detection module900includes one or more photodetectors916which can either be integrated on sensor chip904or separately placed on substrate carrier902. The touch sensor for detecting a contact from an object can be implemented using conductive material having a shape corresponding to the fingerprint detection module, such as a metal ring908placed around and slightly above the protective cover to protect the border of the protective cover. The touch sensor can serve as a sensing electrode to detect a contact from an object920with the fingerprint detection module900. In fingerprint detection module900, one or more light emitting sources910are located directly under protective cover906within a gap between protective cover906and substrate carrier902and close to an edge of sensor chip904. Thus, unlike the fingerprint detection module400, the metal ring908in fingerprint detection module900does not include a cavity for housing the light emitting sources910. In some implementations, light emitting sources910can emit at least two different wavelengths.

To allow detection light signals emitted from light emitting sources910to pass through protective cover906and reach object920, the protective cover906is transparent to the detection lights. When protective cover906is coated with a colored layer on the bottom surface to achieve a desired appearance, the colored layer can be opaque to the wavelengths of lights emitted by light emitting sources910, which are placed directly underneath the colored layer.

FIG. 9Billustrates an exemplary fingerprint detection module901which includes a protective cover coated with a colored layer in accordance with some embodiments described herein. As can be seen inFIG. 9B, fingerprint detection module901includes substrate carrier902, sensor chip904, protective cover906, metal ring908, one or more light emitting sources910located underneath protective cover906, and one or more photodetectors916. A colored layer912is coated on the bottom surface of protective cover906to provide the intended color appearance. The color layer912is transparent to the light emitted from light emitting sources910to allow the emitted light to pass through the colored layer912and reach an object making contact with protective cover906. Moreover, the color layer912is transparent to reflected light from the object making contact with the protective cover906to reach photodetectors916which is also located underneath colored layer912. In the embodiment shown inFIG. 9B, transparency to emitted light and reflected light is achieved using multiple micro-holes914created through colored layer912in the regions directly above light emitting sources910and photodetectors916. These micro-holes914can be sufficiently small so that they are not visible to a user but large enough to allow emitted light from light emitting sources910to pass through and reach an object and reflected light from an object to pass though and reach photodetectors916. For example, the size of the multiple micro-holes can be from about 1 μm to a few μm. In some implementations, micro-holes914are formed in the colored layer912using a laser.

In various embodiments of a fingerprint detection module described above (i.e., fingerprint detection modules100,300,400,900, and901), the fingerprint sensor chip in a respective fingerprint detection module can have a thickness between 200 μm to 500 μm. The substrate in a respective fingerprint detection module can have a thickness between 0.5 mm to 2 mm. The metal ring in a respective fingerprint detection module can have a thickness between 0.5 mm to 2 mm. The thickness of the protective cover in a respective fingerprint detection module can be between 100 μm to 500 μm. The protective cover, e.g., protective cover106, can be made of entirely by a single material, e.g., sapphire, zirconia, or ceramic. However, in some implementations, a protective cover can be made of at least two layers: a top layer of a relatively hard and more expensive material of high dielectric-constant (e.g., sapphire, zirconia, or diamond-like carbon) and a bottom layer of relatively less expensive material of high dielectric-constant (e.g., a ceramic material such as aluminum nitride (AlN)). For example, if a protective cover has an overall thickness of 450 μm, the top layer can be made of 150 μm of sapphire and the bottom layer can be made of 300 μm AlN. Such double layer structure can lower the overall cost of the protective cover while maintaining sufficiently high hardness and dielectric strength.

FIG. 9Cillustrates an exemplary reduced size fingerprint detection module930as a variation on the fingerprint detection module430for determining whether an image captured of an object making contact with the reduced size fingerprint detection module930matches a registered finger print of an authorized user. The reduced size fingerprint detection module930is substantially similar to fingerprint detection module900except for the smaller size and a differing shape (e.g., shaped in a strip).

Similarly to fingerprint detection module430, fingerprint detection module930includes substrate carrier932, protective cover936, touch sensor or sensing electrode such as a metal ring938and a reduced size sensor chip934, which may include a capacitive sense array for sensing a fingerprint's ridge and valley patterns. Also, fingerprint detection module930includes one or more photodetectors946which can either be integrated on sensor chip934or separately placed on substrate carrier932. The touch sensor for detecting a contact from an object can be implemented using conductive material having a shape corresponding to the fingerprint detection module, such as a metal ring938placed around and slightly above the protective cover to protect the border of the protective cover. The touch sensor can serve as a sensing electrode to detect a contact from an object920with the fingerprint detection module930. In fingerprint detection module930, one or more light emitting sources940are located directly under protective cover936within a gap between protective cover936and substrate carrier932and close to an edge of sensor chip934. Thus, unlike the fingerprint detection module430, the metal ring938in fingerprint detection module930does not include a cavity for housing the light emitting sources940. In some implementations, light emitting sources940can emit at least two different wavelengths.

To allow detection light signals emitted from light emitting sources940to pass through protective cover936and reach object920, the protective cover936is transparent to the detection lights. When protective cover936is coated with a colored layer on the bottom surface to achieve a desired appearance, the colored layer can be opaque to the wavelengths of lights emitted by light emitting sources940, which are placed directly underneath the colored layer.

FIG. 9Dillustrates an exemplary reduced size fingerprint detection module950which includes a protective cover956coated with a colored layer962. As can be seen inFIG. 9D, reduced size fingerprint detection module950includes substrate carrier952, reduced size sensor chip954, protective cover956, touch sensor or sensing electrode such as metal ring958, one or more light emitting sources960located underneath protective cover956, and one or more photodetectors966. A colored layer962is coated on the bottom surface of protective cover956to provide the intended color appearance. The color layer962is transparent to the light emitted from light emitting sources960to allow the emitted light to pass through the colored layer962and reach an object making contact with protective cover956. Moreover, the color layer962is transparent to reflected light from the object making contact with the protective cover956to reach photodetectors966which is also located underneath colored layer962. In the embodiment shown inFIG. 9D, transparency to emitted light and reflected light is achieved using multiple micro-holes964created through colored layer962in the regions directly above light emitting sources960and photodetectors966. These micro-holes964can be sufficiently small so that they are not visible to a user but large enough to allow emitted light from light emitting sources960to pass through and reach an object and reflected light from an object to pass though and reach photodetectors966. For example, the size of the multiple micro-holes can be from about 1 μm to a few μm. In some implementations, micro-holes914are formed in the colored layer962using a laser.

In various embodiments of a reduced size fingerprint detection module described above(i.e., fingerprint detection modules120,320,430,930, and950), a reduced size fingerprint sensor chip in a respective reduced size fingerprint detection module can have a thickness between 200 μm to 500 μm. The substrate in a respective fingerprint detection module can have a thickness between 0.5 mm to 2 mm. The metal ring in a respective fingerprint detection module can have a thickness between 0.5 mm to 2 mm. The thickness of the protective cover in a respective fingerprint detection module can be between 100 μm to 500 μm. The protective cover, e.g., protective cover956, can be made of entirely by a single material, e.g., sapphire, zirconia, or ceramic. However, in some implementations, a protective cover956can be made of at least two layers: a top layer of a relatively hard and more expensive material of high dielectric-constant (e.g., sapphire, zirconia, or diamond-like carbon) and a bottom layer of relatively less expensive material of high dielectric-constant (e.g., a ceramic material such as aluminum nitride (AlN)). For example, if a protective cover has an overall thickness of 450 μm, the top layer can be made of 150 μm of sapphire and the bottom layer can be made of 300 μm AlN. Such double layer structure can lower the overall cost of the protective cover while maintaining sufficiently high hardness and dielectric strength.

FIG. 10presents a diagram of an exemplary fingerprint detection system1000for performing human fingerprint detection and authentication in accordance with some embodiments described herein. As shown inFIG. 10, fingerprint detection system1000includes a touch sensing module1002which includes a touch sensor (such as a metal ring) and sensor circuitry for detecting a contact from an object with fingerprint detection system1000. Also, fingerprint detection system1000includes an optical sensor module1004, a fingerprint pattern sensor1006, and an authentication processor1008. Touch sensing module1002is communicatively coupled to optical sensor module1004to combine sensor data from touch and optical sensors. When touch sensing module1002detects a contact from an object, such as a finger, touch sensing module1002activates optical sensor module1004to perform fingerprint analysis. Optical sensor module1004produces probe light at two or more different optical wavelengths to which a person's skin produces different optical responses at the two or more different optical wavelengths due to presence of blood in the person's skin. An optical detection unit in the optical sensor module1004receives a reflection or transmission of the probe light from the object making contact to detect optical measurements that represent reactions of the reflected probe light at the two or more different optical wavelengths. The optical measurements of the reflected probe at different wavelengths can be used to compute values that are compared to standard or calibrated values for human blood absorption to determine whether the detected contact is from human skin. The computation, comparison, and determination of reflected probe light operations can be performed by an on-chip signal processing unit integrated with optical sensor module1004.

Optical sensor module1004is communicatively coupled to fingerprint pattern sensor1006. When optical sensor module1004detects human skin as the object making contact, optical sensor module1004activates fingerprint pattern sensor1006. Fingerprint pattern sensor1006includes a sensor array which obtains fingerprint data and a fingerprint pattern processor that determines whether the obtained fingerprint data resembles a human fingerprint. Fingerprint pattern sensor1006is communicatively coupled to authentication processor1008. When fingerprint pattern sensor1006detects a human fingerprint, fingerprint pattern sensor1006activates authentication processor1008. Authentication processor1008receives the obtained fingerprint data from fingerprint pattern sensor1006and verifies whether the obtained fingerprint data matches stored fingerprint data of an authorized person's fingerprint pattern. Based on the verification outcome, the authentication processor generates authorization decision1010to determine whether the user request to access the locked mobile device is granted or denied.

In a high security operation mode, authentication processor1008can receive optical measurements at two or more optical wavelengths from optical sensor module1004, and used the optical measurements to detect a presence of a human heartbeat signal. This heartbeat detection offers an additional layer of security on whether a live person is associated with the detected human fingerprint. The authentication processor1008then generates authorization decision1010based on both the result of fingerprint authentication and the result of heartbeat detection.

Techniques, systems, and devices are disclosed for performing human fingerprint detection and authentication using an optical detection module in addition to a fingerprint pattern recognition sensor. The disclosed human fingerprint detection and authentication technology can be integrated with mobile devices (e.g., smartphones and tablets) and other devices (e.g., such as computer monitors) to improve the fingerprint authentication technology used in existing devices.