Systems and methods for pressure-based authentication of an input on a touch screen

Systems and methods are provided for authenticating an input on a touch screen. A method comprises obtaining one or more pressure metrics for an input by a user on a touch screen that is being proffered as that of a known user. Each pressure metric corresponds to a pressure applied to the touch screen by the user at a respective impression location of the input. The method further comprises authenticating the user as the known user based at least in part on the one or more pressure metrics.

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally to touch sensing applications, and more particularly, embodiments of the subject matter relate to authorizing signatures impressed on a touch screen.

BACKGROUND

Many electronic devices use touch screens (or touch panels) to present information to a user and also receive input from the user. For example, a touch screen is capable of intuitively and naturally capturing a user's signature. Conventional touch sensing technologies sense the position of touches on a screen. While some touch sensing technologies are able to determine a magnitude of pressure (or force) applied to the touch screen, the pressure is determined based on the area of contact (or the rate of change thereof) on the surface of the touch screen. In this regard, the prior art approximates or extrapolates an estimate of the pressure applied, but does not measure the actual force applied. Furthermore, some capacitive touch screens are responsive to mere proximity to the surface of the touch screen, that is, they may respond or react when in fact no contact or impression has been made on the surface of the touch screen. As a result, prior art systems are not able to accurately measure and resolve the pressure (or force) that is applied against the touch screen to individual locations on the touch screen. Thus, conventional authentication methods for a signature impressed on a touch screen compare the two-dimensional spatial characteristics (e.g., size, shape, orientation, etc.) of the input signature to the spatial characteristics of a stored signature. However, a skilled forger can replicate the spatial characteristics of a user's signature, and thereby compromising the integrity of the authentication.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

Techniques and technologies may be described herein in terms of functional and/or logical block components and various processing steps. It should be appreciated that such block components may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. For example, an embodiment of a system or a component may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices.

The following description refers to elements or nodes or features being “connected” or “coupled” together. As used herein, unless expressly stated otherwise, “connected” means that one element/node/feature is directly joined to (or directly communicates with) another element/node/feature, and not necessarily mechanically. Likewise, unless expressly stated otherwise, “coupled” means that one element/node/feature is directly or indirectly joined to (or directly or indirectly communicates with) another element/node/feature, and not necessarily mechanically.

Technologies and concepts discussed herein relate to systems utilizing pressure-sensing (or force-sensing) touch screens, that is, a touch screen capable of measuring and/or resolving the pressure applied (or force) to one or more individual locations on the touch screen to the respective impression locations. The pressure-sensing touch screen is utilized to authenticate a manual (or handwritten) impression on the surface of a touch screen (or touch panel), such as a signature, that is intended to identify a particular user and proffered as that of the particular user. Although the subject matter is described herein in the context of a signature, the subject matter may be utilized to authenticate any manual impression(s) made on the surface of a touch screen (or touch panel) which is intended to identify a user, such as, for example, a name (cursive or printed), number, symbol, marking, gesture, or another impression intended to identify the user. As described in greater detail below, an input impression(s) on the touch screen (e.g., an input signature) is compared to a template corresponding to a particular user and authenticated as being made by that particular user based on two-dimensional spatial characteristics of the input impression(s), such as the size, shape, and/or orientation of the input signature, as well as the pressure (or force) applied by the user to the touch screen (or touch panel) at the individual impression locations that comprise the input. In an exemplary embodiment, the touch screen comprises a transparent touch panel that is responsive to pressure (or force) applied to the touch panel by any object, such as, for example, a stylus, pointer, pen, a finger and/or hand, a fingernail, or another suitable object.

FIG. 1depicts a signature authentication system100suitable for use with an electronic device116, such as, a computer, server, mobile device (e.g., cellular phone, personal digital assistant, and the like), automated teller machine, credit card reader, cash register, and the like. In an exemplary embodiment, the signature authentication system100includes, without limitation, a touch screen102, touch panel control circuitry104, a processing module106, an input device108, and a data storage element110. It should be understood thatFIG. 1is a simplified representation of a signature authentication system100for purposes of explanation and is not intended to limit the scope of the subject matter in any way. In this regard, althoughFIG. 1depicts the input device108as being part of the electronic device116, in practice, the input device108may be separate from the electronic device116and communicatively coupled to the processing module106(e.g., via a wireless link). Similarly, in practice, the data storage element110may reside at a remote location (e.g., on a server) and be communicatively coupled to the processing module106, for example, over a network (e.g., a local area network, a credit card or debit card transaction network).

In an exemplary embodiment, the touch screen102comprises a touch panel112and a display device114. The touch panel112is coupled to the touch panel control circuitry104, which, in turn, is coupled to the processing module106. The processing module106is coupled to the display device114and is configured to control the rendering and/or display of one or more graphical objects on the display device114and correlates information received from the touch panel control circuitry104with the content displayed on the display device114. The processing module106is also communicatively coupled to the input device108and the data storage element110to support operation of the signature authentication system100, as described in greater detail below.

In an exemplary embodiment, the touch panel112is realized as a transparent touch panel that is responsive to pressure (or force) applied to one or more locations on the touch panel112. In this regard, the touch panel112is pressure-sensitive (or force-sensitive) and may be utilized to determine the pressure (or force) applied to the touch panel112by the various impressions that comprise an input signature (or another input impression) on the touch screen102and resolve the pressure (or force) to the respective impression locations on the touch panel112, as described in greater detail below. The touch panel112is preferably disposed proximate the display device114and aligned with respect to the display device114such that the touch panel112is interposed in the line-of-sight between a user and the display device114when the user views content displayed on the touch screen102and/or display device114. In this regard, from the perspective of a user and/or viewer of the touch screen102and/or display device114, at least a portion of the touch panel108overlaps and/or overlies content displayed on the display device114. In accordance with one embodiment, the touch panel108is substantially planar in shape and disposed adjacent to a substantially planar surface of the display device114, as described in greater detail below.

FIG. 2depicts an exploded view of a transparent touch panel200suitable for use as the touch panel112in the touch screen102ofFIG. 1in an exemplary embodiment. The touch panel200includes, without limitation, a transparent protective layer202, a first transparent electrode layer204, a transparent composite layer206, a second transparent electrode layer208, and a transparent substrate210. The transparent protective layer202comprises a transparent protective material, such as glass or a polymer, which is disposed over the first transparent electrode layer204. In an exemplary embodiment, the transparent substrate210is realized as a rigid material, such as, for example, glass or a polymer, however in alternative embodiments, the transparent substrate210may be realized as a flexible material. As described in greater detail below, in an exemplary embodiment, the transparent composite layer206is interposed between the transparent electrode layers204,208.

In an exemplary embodiment, each of the transparent electrode layers204,208is realized as a patterned layer having a plurality of transparent conductive traces205,209, with each conductive trace being electrically coupled to a tab211,213for providing an electrical connection to other circuitry. In this regard, in accordance with one embodiment, the tabs211,213are coupled to the touch panel control circuitry104ofFIG. 1. In an exemplary embodiment, the transparent conductive traces205,209are realized as a transparent conductive oxide, such as, indium tin oxide, zinc oxide, or tin oxide. The second transparent electrode layer208is deposited on the transparent substrate210with the conductive traces209being aligned in a first direction. For example, as shown inFIG. 2, the conductive traces209are aligned with and/or parallel to the x-axis. The first transparent electrode layer204is deposited on the transparent composite layer206with its conductive traces205being aligned orthogonal to the conductive traces209of the second transparent electrode layer208. For example, as shown inFIG. 2, the conductive traces205are aligned with and/or parallel to the y-axis.

By virtue of the orthogonal orientation of the conductive traces205,209, the transparent electrode layers204,208produce a plurality of possible conducting paths from conductive traces205of the first transparent electrode layer204through the transparent composite layer206to conductive traces209of the second electrode layer208at each location where the conductive traces205,209are overlapping and/or overlying along the z-axis. In this regard, the transparent electrode layers204,208produce an m×n array (or matrix) of potential conducting paths through the transparent composite layer206, where m is the number of rows of conductive traces209of the second electrode layer208and n is the number of columns of conductive traces205of transparent electrode layer204. For example, in accordance with one embodiment, the second electrode layer208comprises24conductive traces209and the first transparent electrode layer204comprises32conductive traces205resulting in a 24×32 array of potential conducting paths.

In an exemplary embodiment, the transparent composite layer206is realized as a resilient material with transparent conductive (or semiconductive) particles uniformly dispersed within the material. For example, depending on the embodiment, the transparent composite layer206may comprise a transparent elastomeric matrix, such as, polyester, phenoxy resin, polyimide, or silicone rubber, with transparent conductive or semiconductive particles such as indium tin oxide, zinc oxide, or tin oxide dispersed within the material.

When pressure (or force) is applied to the surface of the touch panel200and/or transparent protective layer202(e.g., in the positive z-direction), the transparent composite layer206is compressed, thereby reducing the average distance between adjacent conductive particles dispersed within the transparent composite layer206underlying that particular location. In other words, the conductive paths formed by networks of adjacent particles increase in density (also known as percolation), thus increasing the conductance (or decreasing the resistance) of the transparent composite layer206between overlapping conductive traces of transparent electrode layer204,208at the location(s) corresponding to the pressure applied to the touch panel200and/or transparent protective layer202(e.g., the impression location). Thus, a heavier force (or pressure) applied to the touch panel200and/or transparent protective layer202in the positive z-direction results in greater compression of the transparent composite layer206, and thereby, a greater increase in conductivity (or decrease in resistance) of the transparent composite layer206at the particular impression location. In this manner, the transparent composite layer206acts as a variable resistance that is electrically in series with each conducting path between transparent electrode layers204,208, wherein the amount of resistance for a respective conducting path is directly related to the magnitude of the pressure (or force) applied to the touch panel200at the location corresponding to the respective conducting path (i.e., the location overlying the conducting path along the z-axis). As described in greater detail below, the resistance (or the change thereof) is measured or otherwise determined for each conducting path of the plurality of conducting paths, that is, each location of the m×n array, to determine the pressure (or force) applied to the surface of the touch panel200and/or transparent protective layer202at the locations on the touch panel200and/or transparent protective layer202corresponding to the respective conducting path (e.g., overlying along the z-axis). As described in greater detail below, based on the resistance (or the change thereof) for each conducting path, a pressure (or force) metric for each conducting path is obtained, wherein the pressure (or force) metric is indicative of the magnitude of the pressure (or force) applied to the touch panel200and/or transparent protective layer202overlying the respective conducting path.

Referring again toFIG. 1with continued reference toFIG. 2, in an exemplary embodiment, the touch panel112,200is integral with the display device114to provide a pressure-sensing (or force-sensing) touch screen102. For example, if the display device114has a substantially planar viewing area, the touch panel112,200and/or transparent substrate210may be aligned parallel to the planar viewing area of the display device114. In an exemplary embodiment, the touch panel112,200and display device114are separated by less than about 10 millimeters, however, in some embodiments, the touch panel112,200may be directly adjacent to (or in contact with) the display device114(e.g., a negligible separation distance). The display device114is realized as an electronic display configured to graphically display information and/or content under control of the processing module106. Depending on the embodiment, the display device114may be realized as a liquid crystal display (LCD), a cathode ray tube display (CRT), a light emitting diode (LED) display, an organic light emitting diode (OLED) display, a plasma display, or a projection display, or another suitable electronic display.

Referring again toFIG. 1, with continued reference toFIG. 2, the touch panel control circuitry104generally represents the hardware, software, and/or firmware components of the signature authentication system100which are configured to detect, measure or otherwise determine the resistance (or change thereof) for each conducting path of the plurality of conducting paths of the touch panel112,200, that is, each location where conductive traces205,209of the touch panel112,200overlap to create a conducting path through the transparent composite layer206. In this regard, the touch panel control circuitry104is configured to scan each conducting path (e.g., each location of the m×n array), for example, by applying a reference voltage (or current) to a first conductive trace215of the first transparent electrode layer204and measuring the voltage (or current) at each conductive trace209of the second electrode layer208while maintaining the reference voltage applied to the first conductive trace215. The measured voltage (or current) for each conductive trace209of the second electrode layer208depends on the resistance of the transparent composite layer206between first conductive trace215of the first transparent electrode layer204and the respective conductive trace209of the second electrode layer208. In this manner, the touch panel108,200is pressure-sensing (or force-sensing) because the measured voltage (or current) directly relates to the pressure (or force) applied to the touch panel112,200overlying (e.g., along the z-axis) the overlap of the first conductive trace215of the first transparent electrode layer204and the respective conductive trace209of the second electrode layer208. After measuring the voltage (or current) for each conductive trace209of the second electrode layer208in response to the applying the reference voltage to the first conductive trace215, the touch panel control circuitry104applies the reference voltage to a second conductive trace217of the first transparent electrode layer204, and while maintaining the reference voltage applied to the second conductive trace217, measures the voltage (or current) of each conductive trace209of the second electrode layer208, and so on until the voltage (or current) has been measured for each possible conducting path.

After measuring the voltage (or current) for each conducting path of the plurality of possible conducting paths, the touch panel control circuitry104converts the measured voltages (or currents) to corresponding pressure (or force) metrics which are indicative of the magnitude of the pressure (or force) applied to the touch panel112,200by an impression overlying the respective conducting path. The touch panel control circuitry104generates a pressure map (or pressure matrix) which maintains the association and/or correlation between pressure metrics and their corresponding location on the touch panel112,200(e.g., the location of the conducting path for the respective pressure metric). In this regard, the pressure map may comprise m×n array (or matrix) corresponding to the conducting paths of the touch panel112,200, wherein each entry of the m×n array is a pressure metric based on the resistance (or change thereof) at the particular location of the touch panel112,200. In this manner, the touch panel control circuitry104and touch panel112,200are cooperatively configured to obtain pressure metrics that correspond to the pressure (or force) applied to the touch panel112,200and/or touch screen102and resolve the pressure metrics to respective impression locations, that is, the location of the conducting path underlying (e.g., in the direction of the z-axis) the location where pressure (or force) is applied to the touch panel112,200. In an exemplary embodiment, the touch panel control circuitry104is configured to generate the pressure map at a rate of about 20 Hz to 200 Hz and provide the pressure map to the processing module106, as described in greater detail below. Thus, each pressure map reflects the state of the pressure (or force) applied to the touch panel112,200at a particular instant in time.

FIG. 3depicts a static representation of a pressure map for an input signature302impressed upon a touch screen300that form a capital letter ‘B’. It should be understood that in practice, the location(s) of the impression(s) comprising the signature302and the corresponding pressure metrics will vary over time and be captured by a plurality of individual pressure maps, which are correlated or otherwise combined into a time-varying signature pressure map, as described in greater detail below. Each pressure map corresponds to the state of the input impressions (e.g., input signature) on the touch screen300, that is, the one or more impression locations and their corresponding pressure metrics, at a particular instant in time. For example, if the touch panel control circuitry104captures pressure maps at a rate of 60 Hz, each pressure map represents the state of the input signature on the touch screen102,300and/or touch panel112,200every sixtieth of a second.

As shown inFIG. 3, the pressure map is realized as an array comprising24rows of cells308and32columns of cells304. In this regard, the touch screen300includes a transparent pressure-sensing touch panel, such as the touch panel200ofFIG. 2, wherein the rows of cells308correspond to the rows of conductive traces of the touch panel that are aligned along the x-axis (e.g., conductive traces209) and the columns of cells304correspond to columns of conductive traces of the touch panel aligned along the y-axis (e.g., conductive traces205). In this regard, each cell corresponds to a conducting path where conductive traces are overlying along the z-axis, wherein the shading of each cell corresponds to the magnitude of the pressure (or force) applied to the touch screen300in the direction of the z-axis overlying the respective conducting path. As shown inFIG. 3, in practice, an impression on the touch screen300may overlap multiple conducting paths of the touch screen300resulting in multiple impression locations being detected by the touch screen300and/or signature authentication system100. In response to detecting an input impression (e.g., input signature302) on the touch screen102,300, the processing module106may display a graphical representation of the input impression303on the display device114that corresponds to and tracks the impression(s) on the touch screen102,300. As shown inFIG. 3, the processing module106may display the graphical representation of the signature303by interpolating the two-dimensional (x, y) location information for the impression locations of the input signature302to provide a finer resolution for the graphical representation of the signature303.

Referring again toFIG. 1, with continued reference toFIGS. 2 and 3, in an exemplary embodiment, the input device108is communicatively coupled to the processing module106and adapted to allow a user to identify himself or herself (e.g., by entering a username or an identification number) or otherwise obtain a user identifier to be associated with an input signature (or another input impression) on the touch screen102, as described in greater detail below. In various embodiments, the input device108may be realized as a keypad, keyboard, card reader (e.g., a credit card reader, debit card reader, access card reader, smart card reader, and the like), barcode reader, radio-frequency identification (RFID) reader, magnetic stripe reader, mouse, joystick, knob, microphone, or another suitable device. In an exemplary embodiment, the data storage element110is realized as a database configured to maintain an association between a user identifier and a signature template corresponding to the user identifier, as described in greater detail below.

The processing module106generally represents the hardware, software, and/or firmware components configured to facilitate the authentication of an input signature on the touch screen102and/or touch panel112and perform additional tasks and/or functions described in greater detail below. Depending on the embodiment, the processing module106may be implemented or realized with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. The processing module106may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration. In practice, the processing module106includes processing logic that may be configured to carry out the functions, techniques, and processing tasks associated with the operation of the signature authentication system100, as described in greater detail below. Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by the processing module106, or in any practical combination thereof.

Referring now toFIG. 4, in an exemplary embodiment, a signature authentication system may be configured to perform a configuration process400and additional tasks, functions, and/or operations as described below. The various tasks may be performed by software, hardware, firmware, or any combination thereof. For illustrative purposes, the following description may refer to elements mentioned above in connection withFIG. 1andFIG. 2. In practice, the tasks, functions, and operations may be performed by different elements of the described system, such as the touch screen102, touch panel112,200, touch panel control circuitry104, processing module106, input device108and/or data storage element110. It should be appreciated any number of additional or alternative tasks may be included, and may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein.

Referring now toFIG. 4, and with continued reference toFIGS. 1-3, a configuration process400may be performed to create a signature template (or signature model) from one or more configuration signatures which will be used as a key to verify and/or authenticate an input signature on a touch screen that is subsequently proffered as that of a particular user. Depending on the embodiment, the input signature may comprises a name (cursive or printed), number, symbol, marking, gesture, or another impression on the touch screen made by a user which is intended to identify the user. In an exemplary embodiment, the configuration process400begins by identifying a desired number of configuration signatures to be used to create the signature template (task402). In this regard, using multiple signatures to create the signature template compensates for biometrically insignificant variations in an individual's signature over time and provides a robust model for the user's signature. The configuration process400may be configured for a default number of configuration signatures, or alternatively, the configuration process400may identify the desired number of configuration signatures in response to a user input (e.g., via input device108and/or touch screen102).

In an exemplary embodiment, the configuration process400continues by obtaining a user identifier to be associated with the signature template and thereby identifying the user associated with the configuration signature(s) (task404). The user identifier is preferably a unique identifier used to associate the signature template with a unique user, as described in greater detail below. The user identifier may comprise a name, identification number, account number, government issued number, or some other identifying information that is unique to a particular user. The user identifier may be obtained via the input device108, for example, by a user swiping a card containing identification information (e.g., an access card, credit card, debit card, or the like) or by a user manually entering his or her identification information via the input device108and/or touch screen102.

In accordance with one embodiment, in response to obtaining the user identifier, the processing module106renders and/or displays a signature capture area on the display device114, such as, for example, a signature box or a signature line. The configuration process400continues by obtaining, capturing, or otherwise determining pressure metrics for the one or more impressions comprising the configuration signature for the identified user and generating a signature pressure map of the configuration signature (tasks406). As used herein, the signature pressure map (S(t)) comprises to a three-dimensional time-varying representation of the signature that represents the two-dimensional positional information for the impression locations on the touch screen102and/or touch panel112,200along with the pressure metrics corresponding to the pressure (or force) applied at the respective impression locations with respect to time (e.g., S(t)=[x(t), y(t), p(t)]). In an exemplary embodiment, the touch panel control circuitry104obtains and/or generates one or more pressure maps in response to an impression on the touch panel112,200, wherein each pressure map comprises pressure metrics for the conducting paths of the touch panel112,200in response to the configuration signature at a particular instant in time. In this regard, the each pressure map reflects the state of the input impression(s) on the touch screen102and/or touch panel112,200as the configuration signature progresses from an initial location to completion.

In an exemplary embodiment, the touch panel control circuitry104provides the one or more pressure maps to the processing module106which determines the signature pressure map (e.g., the three-dimensional time-varying representation of the configuration signature) by correlating or otherwise combining the one or more pressure maps to obtain the time-varying signature pressure map for the configuration signature. In an exemplary embodiment, the processing module106generates the signature pressure map by first converting the pressure metrics to varying intensity values or grayscale, for example, by dividing each pressure metric by the maximum pressure metric for the configuration signature. After converting the pressure metrics to grayscale, the processing module106interpolates the pressure maps generated by the touch panel control circuitry104to obtain the signature pressure map (S(t)). By applying an interpolation method, such as Bézier curve fitting or spline interpolation, to the discrete-time (or sampled) pressure maps generated by the touch panel control circuitry104, the signature pressure map more accurately reflects the impression(s) made by the user on the touch screen102and/or touch panel112,200when inputting the configuration signature.

After generating the signature pressure map, in an exemplary embodiment, the configuration process400continues by determining verification data for the captured signature based on the obtained signature pressure map (task408). In this regard, the processing module106calculates, computes, or otherwise determines data which may be used to verify the authenticity of a subsequent input signature associated with the user identifier and/or user. For example, the processing module106may calculate or determine the velocity of the signature in the horizontal and/or vertical direction (e.g., x′(t), y′(t)), the acceleration of the signature in the horizontal and/or vertical direction (e.g., x″(t), y″(t)), the jerk of the signature in the horizontal and/or vertical direction (e.g., x′″(t), y′″(t)), as well as various derivatives of the pressure (p(t)).

In an exemplary embodiment, the configuration process400continues by normalizing the signature pressure map (task410). In this regard, the configuration process400rotates, scales, and/or transforms the signature pressure map to eliminate signature variations, such as the alignment of the signature, that do not contain or otherwise represent significant and/or valuable biometric information for purposes of user authentication. For example, if the processing module106displays a signature capture area on the display device114, the processing module106may rotate, scale, and/or transform the signature pressure map such that the signature pressure map is centered with respect to the signature capture area. If the processing module106displays a signature line or signature box on the display device114, the processing module106may rotate and/or transform the signature pressure map such that the signature pressure map is substantially aligned with the signature line or signature box.

After normalizing the signature pressure map, in an exemplary embodiment, the configuration process400continues by determining or otherwise generating a signature template based on the normalized signature pressure map for the configuration signature (task412). In an exemplary embodiment, the signature template comprises a model of the identified user's signature obtained by applying a machine learning model (or machine learning algorithm), an artificial neural network, or another suitable modeling technique to the normalized signature pressure map for the configuration signature, such as, for example, a hidden Markov model, a k-nearest neighbor algorithm, a multilayer perceptron or another suitable feedforward neural network, a radial basis function network, a support vector machine, or the like. In this manner, the signature template (or signature model) captures the two-dimensional characteristics (e.g., [x(t), y(t)]) of the configuration signature(s) (e.g., the user's handwriting) and along with the pressure applied by the user at the various impression locations that comprise the configuration signature (e.g., p(t)). In an exemplary embodiment, the signature template (or signature model) also reflects the verification data and/or other biometric information such as the velocity of the signature in the horizontal and/or vertical direction, the acceleration of the signature in the horizontal and/or vertical direction, and the jerk of the signature in the horizontal and/or vertical direction.

In an exemplary embodiment, the configuration process400continues by determining whether the desired number of configuration signatures have been obtained (task414). If the desired number of configuration signatures have not been obtained, the loop defined by tasks406,408,410,412and414repeats until the desired number of configuration signatures have been obtained. For example, the processing module106may reset the display device114and/or touch screen102or otherwise indicate to the user to input another configuration signature on the touch screen102and/or touch panel112. For each configuration signature, the configuration process400obtains a normalized signature pressure map in a similar manner as describe above (tasks406,408,410), however, for each subsequently obtained signature pressure map, the configuration process400updates the signature template (or signature model) by applying the particular machine learning model (or machine learning algorithm), artificial neural network, or modeling technique to each subsequently obtained normalized signature pressure map, thereby training the signature model for the identified user, such that the signature template (or signature model) reflects the most recently received configuration signature (task412). Once the desired number of configuration signatures has been obtained, the configuration process400continues by maintaining the association of the user identifier and the signature template (task416). In an exemplary embodiment, the processing module106stores the signature template (or signature model) to the database110which maintains the association between the user identifier and the signature template for subsequent authentication.

Referring now toFIG. 5, in an exemplary embodiment, a signature authentication system may be configured to perform an authentication process500and additional tasks, functions, and/or operations as described below. The various tasks may be performed by software, hardware, firmware, or any combination thereof. For illustrative purposes, the following description may refer to elements mentioned above in connection withFIG. 1andFIG. 2. In practice, the tasks, functions, and operations may be performed by different elements of the described system, such as the touch screen102, touch panel112,200, touch panel control circuitry104, processing module106, input device108and/or data storage element110. It should be appreciated any number of additional or alternative tasks may be included, and may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein.

Referring now toFIG. 5, and with continued reference toFIGS. 1-4, an authentication process500may be performed to authenticate or otherwise verify that an input signature (or another input impression) on a touch screen and/or touch panel proffered on behalf of a known user was actually input by that known user, for example, to subsequently allow the user to access to a device or service. In an exemplary embodiment, the authentication process500begins by identifying the user to be authenticated by obtaining the user identifier associated with the particular user (task502). For example, the processing module106may identify the user via the input device108and/or touch screen102in a similar manner as set forth above in the context of FIG.4(e.g., task404). The authentication process500continues by obtaining, capturing, or otherwise determining, using the touch screen, pressure metrics for the impression(s) of the input signature proffered on behalf of the identified user and generating a signature pressure map of the input signature (task504). In this regard, the touch panel control circuitry104captures and/or generates one or more pressure maps in response to the input signature on the touch panel112,200, and provides the one or more pressure maps to the processing module106which correlates or otherwise combines the pressure maps to generate a signature pressure map of the input signature, in a similar manner as described above in the context ofFIG. 4(e.g., task406). After obtaining the signature pressure map for the input signature, in an exemplary embodiment, the authentication process500continues by determining verification data for the input signature based on the obtained input signature pressure map and normalizing the input signature pressure map (tasks506,508), in a similar manner as set forth above in the context ofFIG. 4(e.g., tasks408,410).

In an exemplary embodiment, the authentication process500obtains the signature template associated with or otherwise corresponding to the identified user (task510). In this regard, the processing module106obtains the signature template from the database110associated with the identified user identifier (e.g., task502). After obtaining the appropriate signature template, the authentication process500continues by comparing the normalized signature pressure map for the input signature to the signature template (or signature model) and determining whether the normalized input signature pressure map matches the signature template (task512). In this regard, the processing module106applies one or more similarity measures, such as dynamic time warping, to the determine whether the normalized input signature pressure map matches the signature template (or signature model) or otherwise determines the probability that the normalized input signature pressure map follows or is otherwise in accordance with the learned signature model for the identified user. If the input signature does not match the signature template for the identified user, for example, if the probability of the input signature following the signature template (or signature model) is less than fifty percent, the authentication process500does not authenticate the input signature, thereby preventing the user from access to a particular device (e.g., electronic device116or another device associated with and/or controlled by electronic device116), service, or location associated with the signature authentication system (task514).

In response to determining the input signature matches the signature template, for example, if the probability of the input signature following the signature template (or signature model) is greater than fifty percent, the authentication process500determines the input signature was input or otherwise made by the identified user (task516). In this regard, the signature authentication system100and/or electronic device116authenticates the user, and thereby, may allow the user to access a particular device, service, or location associated with the signature authentication system100. For example, the processing module106may allow the user to access and/or control the electronic device116or provide the user with access to a desired service (e.g., a credit card network, debit card network, or the like) via the electronic device116. Alternatively, the signature authentication system100may be configured to allow the user access to another device or a particular location (e.g., a laboratory, office building, government building, or the like) that the signature authentication system100and/or electronic device116controls access to. In an exemplary embodiment, when the input signature matches the signature template (or signature model), the authentication process500updates the signature template (or signature model) to reflect the authenticated input signature (task518), in a similar manner as set forth above in the context ofFIG. 4(e.g., task412). By dynamically updating the signature template with authenticated and/or verified signatures, the template (or model) accounts for variations in a user's signature over time.

To briefly summarize, one advantage of the systems and/or methods described above is that additional biometric information pertaining to the pressure applied by a user throughout entering his or her signature on a touch screen and/or touch panel is utilized to authenticate a signature proffered on behalf of the user. A transparent pressure-sensing touch panel is utilized to obtain pressure metrics based on a change in resistance and/or conductivity which is directly related to pressure applied to the touch panel, such that the transparent pressure-sensing touch panel is used to effectively measure the pressure applied to the touch screen and/or touch panel by an input signature. The transparent pressure-sensing touch panel resolves the applied pressure to individual pressure metrics associated with individual impressions of the input signature, such that the pressure applied by each impression may be utilized in authenticating and/or verifying the input signature. This improves the integrity of the authentication process and increases the difficulty of forging a user's signature.