PATENT DOCUMENT

Publication Number: US-10007830-B2
Application Number: US-201715617056-A
Country: US
Kind Code: B2

Title: Finger biometric sensor including capacitance change sensing pressure sensing circuit and related methods

Abstract:
A finger biometric sensor may include a lower conductive layer, an upper conductive layer, and a spacer between the lower and upper conductive layers to define an air gap therebetween. The finger biometric sensor may also include a finger biometric sensing integrated circuit (IC) above the upper conductive layer and capable of deflecting the upper conductive layer toward the lower conductive layer to change a capacitance thereof based upon pressure applied to the finger biometric sensing IC. A pressure sensing circuit may be coupled to the lower and upper conductive layers to sense the change in capacitance.

Claims:
That which is claimed is: 
     
       1. A biometric sensor comprising:
 a lower conductive layer; 
 an upper conductive layer spaced above the lower conductive layer; 
 a biometric sensing circuit above the upper conductive layer and configured to deflect the upper conductive layer toward the lower conductive layer to change a capacitance thereof based upon pressure applied to the biometric sensing circuit, the biometric sensing circuit configured to sense biometric data for at least one authentication function; and 
 a capacitance sensing circuit coupled to the lower and upper conductive layers. 
 
     
     
       2. The biometric sensor of  claim 1  further comprising a first dielectric layer between the biometric sensing circuit and the upper conductive layer. 
     
     
       3. The biometric sensor of  claim 1  further comprising a second dielectric layer above the biometric sensing circuit. 
     
     
       4. The biometric sensor of  claim 1  further comprising a sidewall extending upwardly from the lower conductive layer and defining a recess receiving therein the upper conductive layer, and biometric sensing circuit. 
     
     
       5. The biometric sensor of  claim 1  further comprising a flexible circuit coupled to the biometric sensing circuit; and wherein the lower conductive layer has an opening therein receiving the flexible circuit therethrough. 
     
     
       6. The biometric sensor of  claim 1  wherein the biometric sensing circuit comprises an array of electric field biometric sensing pixels. 
     
     
       7. An electronic device comprising:
 a housing; 
 wireless communications circuitry carried by the housing; 
 a biometric sensor carried by the housing and comprising
 a lower conductive layer, 
 an upper conductive layer spaced above the lower conductive layer, 
 a biometric sensing circuit above the upper conductive layer and configured to deflect the upper conductive layer toward the lower conductive layer to change a capacitance thereof based upon pressure applied to the biometric sensing circuit, the biometric sensing circuit configured to sense biometric data for at least one authentication function, and 
 a capacitance sensing circuit coupled to the lower and upper conductive layers; and 
 
 a controller coupled to the wireless communications circuitry and the biometric sensor. 
 
     
     
       8. The electronic device of  claim 7  wherein the controller is configured to perform at least one device function based upon the capacitance sensing circuit. 
     
     
       9. The electronic device of  claim 7  further comprising a display coupled to the controller; and wherein the controller cooperates with the capacitance sensing circuit to prompt a user, via the display, to enroll biometric data at varying pressures adjacent the biometric sensing circuit. 
     
     
       10. The electronic device of  claim 9  wherein the controller is configured to perform at least one authentication function based upon the enrolled biometric data. 
     
     
       11. The electronic device of  claim 7  wherein the biometric sensor further comprises a first dielectric layer between the biometric sensing circuit and the upper conductive layer. 
     
     
       12. The electronic device of  claim 7  wherein the biometric sensor further comprises a second dielectric layer above the biometric sensing circuit. 
     
     
       13. The electronic device of  claim 7  wherein the biometric sensor further comprises a sidewall extending upwardly from the lower conductive layer and defining a recess receiving therein the upper conductive layer, and biometric sensing circuit. 
     
     
       14. The electronic device of  claim 7  further comprising a flexible circuit coupled to the biometric sensing circuit; and wherein the lower conductive layer has an opening therein receiving the flexible circuit therethrough. 
     
     
       15. The electronic device of  claim 7  wherein the biometric sensing circuit comprises an array of electric field biometric sensing pixels. 
     
     
       16. The electronic device of  claim 7  further comprising a pushbutton switch beneath the biometric sensor. 
     
     
       17. A method of using a biometric sensor comprising a lower conductive layer, an upper conductive layer spaced above the lower conductive layer, and a biometric sensing circuit above the upper conductive layer, the biometric sensing circuit configured to sense biometric data for at least one authentication function, the method comprising:
 sensing a change in capacitance caused by deflection of the upper conductive layer toward the lower conductive layer based upon pressure applied to the biometric sensing circuit. 
 
     
     
       18. The method of  claim 17  further comprising using a controller to perform at least one device function based upon the sensed change in capacitance. 
     
     
       19. The method of  claim 17  further comprising using a controller to prompt a user, via a display coupled to the controller, to enroll biometric data at varying pressures adjacent the biometric sensing circuit. 
     
     
       20. The method of  claim 19  further comprising using the controller to perform at least one authentication function based upon the enrolled biometric data.

Description:
TECHNICAL FIELD 
     The present invention relates to the field of electronics, and, more particularly, to the field of finger biometric sensors. 
     BACKGROUND 
     Fingerprint sensing and matching is a reliable and widely used technique for personal identification or verification. In particular, a common approach to fingerprint identification involves scanning a sample fingerprint or an image thereof and storing the image and/or unique characteristics of the fingerprint image. The characteristics of a sample fingerprint may be compared to information for reference fingerprints already in a database to determine proper identification of a person, such as for verification purposes. 
     A fingerprint sensor may be particularly advantageous for verification and/or authentication in an electronic device, and more particularly, a portable device, for example. Such a fingerprint sensor may be carried by the housing of a portable electronic device, for example, and may be sized to sense a fingerprint from a single-finger. 
     Where a fingerprint sensor is integrated into an electronic device or host device, for example, as noted above, it may be desirable to more quickly perform authentication, particularly while performing another task or an application on the electronic device. In other words, in some instances it may be undesirable to have a user perform an authentication in a separate authentication step, for example switching between tasks to perform the authentication. It may also be desirable for a fingerprint sensor to perform other functions beyond authentication. 
     SUMMARY 
     A finger biometric sensor may include a lower conductive layer, an upper conductive layer, and a spacer between the lower and upper conductive layers to define an air gap therebetween. The finger biometric sensor may also include a finger biometric sensing integrated circuit (IC) above the upper conductive layer and capable of deflecting the upper conductive layer toward the lower conductive layer to change a capacitance thereof based upon pressure applied to the finger biometric sensing IC. A pressure sensing circuit may be coupled to the lower and upper conductive layers to sense the change in capacitance. Accordingly, a pressure of the user&#39;s finger may be sensed, for example, for executing a corresponding device function based upon the sensed pressure. 
     The finger biometric sensor may further include a first dielectric layer between the finger biometric sensing IC and the upper conductive layer. A second dielectric layer may be above the finger biometric sensing IC, for example. 
     The finger biometric sensor may include a sidewall extending upwardly from the lower conductive layer and defining a recess receiving therein the spacer, upper conductive layer and finger biometric sensing IC. A flexible circuit may be coupled to the finger biometric sensing IC. The lower conductive layer may have an opening therein receiving the flexible circuit therethrough, for example. The finger biometric sensing IC may include an array of electric field finger biometric sensing pixels, for example. 
     A method aspect may be directed to a method of sensing a change in capacitance using a finger biometric sensor that includes a lower conductive layer, an upper conductive layer, a spacer between the lower and upper conductive layers to define an air gap therebetween, and a finger biometric sensing integrated circuit (IC) above the upper conductive layer. The method may include using a pressure sensing circuit coupled to the lower and upper conductive layers to sense the change in capacitance caused by deflection of the upper conductive layer toward the lower conductive layer. The deflection may be based upon pressure applied to the finger biometric sensing IC. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of an electronic device according to the present invention. 
         FIG. 2  is a schematic block diagram of the electronic device of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the finger biometric sensor of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
     Referring initially to  FIGS. 1-2 , an electronic device  20  is now described. The electronic device  20  illustratively includes a portable housing  21  and a controller  22  carried by the portable housing. The electronic device  20  is illustratively a mobile wireless communications device, for example, a cellular telephone. The electronic device  20  may be another type of electronic device, for example, a tablet computer, laptop computer, etc. In some embodiments, the electronic device  20  may be an integrated circuit for use with another or host electronic device. 
     Wireless communications circuitry  25  (e.g. a wireless transceiver, cellular, WLAN Bluetooth, etc.) is also carried within the housing  21  and coupled to the controller  22 . The wireless transceiver  25  cooperates with the controller  22  to perform at least one wireless communications function, for example, for voice and/or data. In some embodiments, the electronic device  20  may not include a wireless transceiver  25 . 
     A display  23  is also carried by the portable housing  21  and is coupled to the controller  22 . The display  23  may be a liquid crystal display (LCD), for example, or may be another type of display, as will be appreciated by those skilled in the art. A device memory  26  is also coupled to the controller  22 . 
     A finger-operated user input device, illustratively in the form of a pushbutton switch  24 , is also carried by the portable housing  21  and is coupled to the controller  22 . The pushbutton switch  24  cooperates with the controller  22  to perform a device function in response to the pushbutton switch. For example, a device function may include a powering on or off of the electronic device  20 , initiating communication via the wireless communications circuitry  25 , and/or performing a menu function. 
     More particularly, with respect to a menu function, the controller  22  may change the display  23  to show a menu of available applications based upon pressing of the pushbutton switch  24 . In other words, the pushbutton switch  24  may be a home switch or button, or key. Of course, other device functions may be performed based upon the pushbutton switch  24 . In some embodiments, the finger-operated user input device  24  may be a different type of finger-operated user input device, for example, forming part of a touch screen display. Other or additional finger-operated user input devices may be carried by the portable housing  21 . 
     Referring now additionally to  FIG. 3 , the electronic device  20  includes a finger biometric sensor  50  carried by the pushbutton switch  24 . The finger biometric sensor  50  includes a lower conductive layer  51 . The lower conductive layer  51  may be coupled to a voltage reference, for example, ground  52 . A sidewall  53  extends upwardly from the lower conductive layer  51  and defines a recess  54  for receiving the components of the finger biometric sensor, as will be explained in further detail below. The sidewall  53  together with the lower conductive layer  51 , define a finger sensor housing or trim, as will be appreciated by those skilled in the art. 
     The finger biometric sensor  50  also includes an upper conductive layer  55 . The upper conductive layer  55  is spaced apart from the lower conductive layer  51  by way of a spacer  56  between the upper and lower conductive layers. The spacer  56  defines an air gap  57  between the upper and lower conductive layers  55 ,  51 . 
     A first dielectric layer  61  carries the upper conductive layer  55  on a lower surface thereof. The first dielectric layer  61  may include glass, for example, and have a thickness that is selected based upon a stiffness thereof. In other words, a thicker first dielectric layer  61  may increase stiffness, while a thinner first dielectric layer may reduce stiffness. The first dielectric layer  61  may include another material. In an example embodiment, the first dielectric layer  61  may have a thickness of 210 microns, for example. 
     The finger biometric sensor  50  also includes a finger biometric sensing integrated circuit (IC)  62  above the upper conductive layer  55 , and more particularly, carried by an upper surface of the first dielectric layer  61 . In an example embodiment, the finger biometric sensing IC  62  may have a thickness of about 100 microns, for example. 
     The finger biometric sensing IC  62  includes an array of electric field finger biometric sensing pixels to sense a user&#39;s finger  40  or an object placed adjacent the array of finger biometric sensing pixels. The finger biometric sensing IC  62  is carried by the pushbutton switch  24  so that when a user or object contacts and/or presses downward on the pushbutton switch, data from the user&#39;s finger  40  is acquired, for example, for finger matching and/or spoof detection, as will be described in further detail below. In other words, the finger biometric sensing IC  62  may cooperate with circuitry, as will be explained in further detail below, to be responsive to static contact or placement of the user&#39;s finger  40  or object. Of course, in other embodiments, for example, where the finger biometric sensing IC  62  is not carried by a pushbutton switch  24 , the array of finger biometric sensing pixels may cooperate with circuitry to be responsive to sliding contact (i.e. a slide sensor), or responsive to static placement (i.e. a standalone static placement sensor). Further details of electric field finger biometric sensing pixels are disclosed in U.S. Pat. No. 5,940,526 to Setlak et al., assigned to the present assignee, and the entire contents of which are herein incorporated by reference. 
     A second dielectric layer  64  is carried by an upper surface of the finger biometric sensing IC  62 . The second dielectric layer  64  may be direct bonded to the finger biometric sensing IC  62  which may permit the second dielectric layer to be thinner than would otherwise be possible using conventional bonding techniques, for example, such as using glue. The second dielectric layer  64  may include sapphire, for example, and may be oxy-nitride treated. The second dielectric layer  64  may include another material. In an example embodiment, the second dielectric layer  64  may have a thickness of about 190 microns. In some embodiments, a cosmetic coating may be between the upper surface of the finger biometric sensing IC  62  and a lower surface of second dielectric layer  64 . 
     The first dielectric layer  61  and the lower conductive layer  51  each have an opening  65 ,  66  therein. A flexible circuit  67  is coupled to the finger biometric sensing IC  62  and extends through the openings  65 ,  66 , and, for example, to the controller  22 . 
     During operation, a user&#39;s finger  40  is positioned adjacent the finger biometric sensing IC  62 , and more particularly, on the second dielectric layer  64 . The user&#39;s finger  40  during operation, provides downward pressure on the second dielectric layer  64 , for example, at varying degrees, and consequently, downward pressure on the finger biometric sensing IC  62  and first dielectric layer  61 . The bottom of the first dielectric layer  61  moves slightly downward with respect to the lower conductive layer  51 . The finger biometric sensing IC  62  deflects the upper conductive layer  55  toward the lower conductive layer  51  to change a capacitance thereof based upon the pressure applied to the finger biometric sensing IC by the second dielectric layer  64 . In other words, the upper and lower conductive layers  51 ,  55  define electrodes of a capacitor that have a varying distance therebetween based upon pressure of the user&#39;s finger adjacent the finger biometric sensing IC  62 . The second dielectric layer  64  may flex slightly under pressure, for example, between about 5-10 microns at the center, which may not cause fatigue damage particularly if the second dielectric layer is oxy-nitride treated. The lower conductive layer  51  acts as a mechanical stop in the case of relatively high pressure. The relatively large area defined by the air gap  57  may increase sensitivity. 
     The finger biometric sensor  50  also includes a pressure sensing circuit  68  coupled to the controller  22  and lower and upper conductive layers  51 ,  55  to sense the change in capacitance. The controller  22  performs at least one device function based upon the sensed change in capacitance. For example, the controller  22  may cooperate with the pressure sensing circuit  68  to display on the display  23  a notification screen based upon a relatively small pressure, display a home page based upon a larger pressure, and turn on wireless communications functions based upon a relatively large pressure. Of course, the controller  22  may cooperate with the pressure sensing circuit  68  to perform any number and/or type of functions based upon different pressures, as will be appreciated by those skilled in the art. 
     The controller  22  may also cooperate with the finger biometric sensing IC  62  to determine a finger match based upon finger biometric data. More particularly, the processor  22  may determine a finger match based upon enrollment data stored in the device memory  26 . The processor  22  may also determine a live finger based upon spoof data. More particularly, the processor  22  may determine a live finger based upon a complex impedance and/or bulk impedance measurement. 
     With respect to enrollment, in some embodiments, the controller  22  may also cooperate with the pressure sensing circuit  68  to prompt a user, via the display  23 , to enroll finger biometric data at varying pressures of the user&#39;s finger adjacent the finger biometric sensing IC  62 . The controller  22  may then perform at least one authentication function based upon the enrolled finger biometric data at the varying pressures. This may be particularly advantageous, for example, for performing a finger match or authentication with fingers having varying degrees of irregularities for example, sweat content and temperature variations, as will be appreciated by those skilled in the art. Additionally, the configuration described herein may be advantageous for low-power finger pressure sensing and increased mechanical robustness, which may, in turn, lead to a smaller finger biometric sensor  50 , for example, a reduction of between 1-1.4 mm in diameter while maintaining performance. 
     In some embodiments, the controller  22  may cooperate with the array of electric field finger biometric sensing pixels  31  to perform a navigation function, for example. Of course the controller  22  may cooperate with the array of electric field finger biometric sensing pixels  31  and/or other circuitry to perform other or additional functions, as will be appreciated by those skilled in the art. 
     A method aspect may be directed to a method of sensing a change in capacitance using a finger biometric sensor  50  that includes a lower conductive layer  51 , an upper conductive layer  55 , a spacer  56  between the lower and upper conductive layers to define an air gap  57  therebetween, and a finger biometric sensing integrated circuit (IC)  62  above the upper conductive layer. The method may include using a pressure sensing circuit  68  coupled to the lower and upper conductive layers  51 ,  55  to sense the change in capacitance caused by deflection of the upper conductive layer toward the lower conductive layer. The deflection may be based upon pressure applied to the finger biometric sensing IC  62 . 
     The present disclosure recognizes that personal information data, including biometric data, in the present technology, can be used to the benefit of users. For example, the use of biometric authentication data can be used for convenient access to device features without the use of passwords. In other examples, user biometric data is collected for providing users with feedback about their health or fitness levels. Further, other uses for personal information data, including biometric data, that benefit the user are also contemplated by the present disclosure. 
     The present disclosure further contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure, including the use of data encryption and security methods that meets or exceeds industry or government standards. For example, personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection should occur only after receiving the informed consent of the users. Additionally, such entities would take any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data, including biometric data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, in the case of biometric authentication methods, the present technology can be configured to allow users to optionally bypass biometric authentication steps by providing secure information such as passwords, personal identification numbers (PINS), touch gestures, or other authentication methods, alone or in combination, known to those of skill in the art. In another example, users can select to remove, disable, or restrict access to certain health-related applications collecting users&#39; personal health or fitness data. 
     Many modifications and other embodiments will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.

Metadata:
Filing Date: 20170608
Publication Date: 20180626
Grant Date: 20180626
Priority Date: 20150930
Inventors: SETLAK, DALE R.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F21/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/017", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/017", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06K9/0002", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06K9/00087", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06V40/1306", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06V40/1306", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F21/32", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06V40/1365", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06V40/1365", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 58406312