(a) Field of the Invention
The present invention relates to a device and a method for measuring pressure, the pressure to be measured being exerted by an object onto a contact area of the pressure measurement device. In particular, the invention relates to methods and devices for coordinate acquisition, navigation input, authentication of a user and command and text input, embodied on the basis of the pressure measurement device.
(b) Brief Description of the Related Art
A very wide variety of devices for measuring pressure have been known for a long time in the prior art. With these devices, for example in order to measure the force exerted by an object, determination may be carried out by recording very small modifications of an elastic contact area. The deflection of the elastic contact area is then a measure of the force or the pressure. The exerted force may also be transmitted to a piezo element and converted into electrical energy by using the piezo element. The electrical energy is then likewise correlated with the level of force exerted. In other known methods in the prior art, an entire inelastic contact area's deflection generated by the force is measured. Known devices of this type are for example the spring balance, the spring displaying the exerted force according to Hooke's law.
In some background art devices, an imaging sensor is employed to store image data of a fingerprint, for example S. K. Ganapathi, “Fingerprint Authentication: Shifting the Electronic Security Paradigm”, SC On-line SC Magazine, www.scmagazine.com, XP-002481772, February 2002. A measuring instrument having a pressure sensor for recording a pressure of a finger on the sensor is furthermore described. Other types of this pressure measurement device are also described in background references, which use for example the weight force of the object or a reference object. For example the beam balance or the inclination balance are devices which fall within this category of pressure measurement devices. One of the disadvantages of the prior art devices is that the planar moment of inertia and elastic modulus of the material comprising the contact area is usually suitable for measurement only in the range of linear elastic deformations (“Hookean range”). If, for example with a spring balance, the Hookean range of the spring is departed from or exceeded by the exerted force, this not only entails the problem that the pressure can no longer be measured correctly by the spring, but the risk also arises that the spring element itself will be deformed so that it becomes unusable for further pressure measurements and must be replaced. Piezo elements, on the other hand, have the disadvantage that they are highly susceptible to influence by external interference. Piezo elements are furthermore subject to certain manufacturing tolerances, which cannot easily be corrected by calibration.
European Patent Application EP 0,919,947 presents a touch-sensitive contact area of a fingerprint sensor. The contact area comprises variable capacitors, which are formed by various mutually insulated material layers. If for example a pressure is exerted onto the contact area by a finger, then the surface deforms according to the ridges and grooves of the skin surface. This deformation of the contact area causes a change in the electrostatic capacitances and can be made available, and evaluated, as an electrical signal by using detection electronics. As another example, U.S. Pat. No. 4,394,773 presents a fingerprint sensor with a contact area or sensor plate, which is based on a piezoelectric material. If pressure is exerted onto the contact area by a finger, then electrical signals are generated by using the piezoelectric material as a function of the pressure, and these can be evaluated accordingly by using an electronic instrument. Although, for example, the two aforementioned systems and methods make it possible to record pressure variations, both EP 0,919,947 and U.S. Pat. No. 4,394,773 nevertheless have the disadvantage that the surface of the sensors must be touch-sensitive. The electronic circuits lying below the surface will therefore necessarily be mechanically stressed, which leads for example to wear phenomena and pronounced ageing.
Various devices for coordinate acquisition are furthermore known in the prior art. These devices make it possible to record planar coordinates, for example in an x and y plane, or even to input further dimensions using device add-ons. For example, the movement of a computer mouse on a surface may be determined by a spoked wheel moving past a photoelectric barrier for each direction and by converting the light pulses correspondingly into x/y coordinates. One of the disadvantages of computer mice is that they are only suitable for coordinate acquisition on a flat plane. In other known methods in the prior art, for example with a trackpad, an object is moving over a touch-sensitive or at least elastic surface so that coordinates on the two-dimensional plane can be recorded along the contact line. This may, for example, be achieved by capacitively sensitive surfaces. Furthermore, trackpads are known in which a force exerted onto the contact area of the trackpad is also recorded in addition to the planar coordinates. The exerted force is determined by using the elasticity of the contact surface. One of the disadvantages of such devices is that the contact area must be made elastic or mobile, which again leads to the disadvantages mentioned above. U.S. Pat. No. 7,162,059 presents such an example for the input of coordinates in x and y directions by using a fingerprint sensor. The method presented in U.S. Pat. No. 7,162,059, however, does not allow for example further coordinate input, for example by using recording pressure. Thus, for example, computer instructions by using a “click” (selection process) executed by pressure are therefore not possible.
Various systems for authenticating a user by using a fingerprint are also known in the prior art. For example, U.S. Pat. No. 7,190,816 presents a method of authentication by using a fingerprint. The fingerprint is recorded as image data by a small fingerprint sensor. Image data of a second fingerprint of the user are also recorded by using the fingerprint sensor. In order to authenticate the user, the image data of the first fingerprint are compared for a match with the image data of the second fingerprint. One disadvantage of such a method is, for example, that authentication with copies of fingerprints, for example by using a finger formed by wax or gelatine, can readily be achieved by other users in a fraudulent or abusive way. Security of the authentication is not therefore guaranteed in all cases. Automatic authentication by using fingerprint sensors is an integral part in many security systems. For instance, fingerprint sensors are installed in laptops, mobile telephones, portable security tokens or computer mice, the user gaining access to particular applications by being authenticated by using a fingerprint. Particularly in the case of security tokens designed for miniaturisation, external effects may lead to the process of authenticating the appropriate person being unsuccessful, or at least made more difficult. Such impeding effects may for example be dirt or sweat, which interfere with the data determination when a part of the body touches the sensor. Temperature changes or injuries, for example of a finger, can also sometimes have a detrimental effect on an authentication process. These effects can be compensated for during authentication by corresponding measures, so-called “exception handling”. One of these measures consists particularly in also recording nonbiometric parameters in addition to the characteristic biometric features. Such a parameter is for example the force applied by a user by using a finger onto a trackpad or a fingerprint sensor, or the corresponding pressure. Another such possibility is for a password or a personal identification number (PIN) also to be input by the user for authentication by using a keypad. This, however, requires additional interaction by the user. There is furthermore the risk that the password will be forgotten by the user or fall into the wrong hands.
Various methods for text input are furthermore described in the background art, in which for example a simplified input device, for example an input wheel or a limited number of keys, are used instead of a full keyboard. For example, particular symbols can in this case be selected by the input device from a multiplicity of symbols that can be represented on a display module. A cursor element is then positioned on the display module by moving the input wheel. The symbol is selected on the basis of the position of the cursor element by pressing the wheel or a key, for example U.S. Pat. No. 6,011,542. One of the disadvantages of this method is that the input wheel responds sensitively to external effects, for example dirt, which accelerates the ageing process of the input device and makes the input device susceptible to operational interference.
It is therefore an object of the present invention to provide a new pressure measurement device and a corresponding pressure measurement method, which does not have the disadvantages mentioned. The pressure measurement device is intended to measure and output the pressure exerted by using an object onto a contact area. In particular, the pressure measurement device should be mechanically simple to produce and maintain. It should furthermore be robust against environmental effects and guarantee high operational reliability. Furthermore, on the basis of the described pressure measurement device, an authentication device based on biometric features is to be provided which does not comprise the disadvantages mentioned above and has a high security standard. A method and a device for navigation input, command input or text input on the basis of the described pressure measurement device are likewise to be provided.
According to the present invention, these objects are achieved in particular by the elements of the independent claims. Other advantageous embodiments may furthermore be found in the dependent claims and the description.
In particular, these objects are achieved by the invention in that a force exerted by a subsurface of an object onto a contact area of a pressure measurement device is measured by using the pressure measurement device and a corresponding pressure value parameter is generated, in that a pressure measurement device comprises an image acquisition module, comprising the contact area, for recording and storing image data of an elastically structured subsurface of the object, pixels of the subsurface being recordable as correspondingly graduated color and/or brightness values of the image data according to their distance from the contact area, in that the pressure measurement device comprises an integration module having a stack memory which can be incremented according to the color and/or brightness values of the image data, the stack memory comprising a readable stack memory level value, in that the pressure measurement device comprises a filter module for generating the pressure value parameters, a pressure value parameter being allocatable by using the filter module to the stack memory level value read out. One of the advantages of the invention is that the contact area can be made immobile, stiff and/or rigid. Since the deformation of such a surface is superfluous to the pressure measurement, it is resistant against material fatigue and correspondingly wearproof. A further advantage of the invention is in particular that the pressure measurement can even be measured in the nonlinear range. For example, a pressure measurement can succeed even with extremely minor contact of the elastically structured surface of the object with the contact area of the image acquisition module. Another advantage of this device is that a pressure measurement is for example possible even under water or in a vacuum. A further advantage of the invention is that the pressure measurement can in principle be carried out with the aid of the same image data as are used to obtain biometric features, for example for authentication. Furthermore, additional components such as piezo elements can be obviated. Besides the pressure value parameter, the pressure measurement device may also generate x/y coordinate data directly by using the image acquisition module and transmit them to further modules.
In an alternative embodiment, these objects are achieved by the invention in that the filter module of the pressure measurement device comprises a lookup table, value pairs which respectively comprise a reference value and a correspondingly allocated pressure value parameter being stored in the lookup table, and in that the filter module comprises a comparison module for comparing a stack memory level value transmitted to the comparison module with the reference values of the lookup table, the corresponding pressure value parameter being allocatable on the basis of the comparison in order to generate the pressure value parameter by using the lookup table. One of the advantages of the invention is that the pressure value parameter can be made available by the lookup table in an extremely short time and read out immediately, since the pressure value parameter does not have to be determined or calculated again before each readout process. Because elaborate calculations are obviated, convenient and resource-saving memory components can be used.
In an alternative embodiment, these objects are achieved by the invention in that the filter module of the pressure measurement device comprises a correlation module for allocating a stack memory level value, transmitted to the correlation module, to a pressure value on the basis of at least one exponentiation and/or at least one multiplication and/or at least one addition factor, the corresponding pressure value parameter being generatable on the basis of the correlation. One of the advantages of the invention is that a pressure value parameter can be calculated exactly on the basis of a stack memory level value according to the correlation factors, the factors being modifiable and adaptable if need be. A further advantage of the invention is that the parameters for such a “fit function” can be adapted according to an object's specific, elastically structured subsurface touching the contact area, so that individualised tuning of the pressure measurement is possible.
In an alternative embodiment, these objects are achieved by the invention in that the pressure measurement device comprises an interface module for generating control signals and/or data signals on the basis of the pressure value parameter. One of the advantages of the invention is that control signals of the pressure measurement device can be transmitted to other devices. These control signals are used, for example, to initiate an event. A further advantage of the invention is that data signals can for example be used to transmit the pressure value to an output unit of the pressure measurement device, such as a display unit, in which case a pressure value may for example be output in the units N/m2, pascals, bars or atmospheres. A further advantage of the invention is that the interface module may also be configured as a bus or line system for interchanging data and/or control signals between potentially more than two subscribers or modules. The output unit may also be produced as an acoustic unit, for instance as a loudspeaker module.
In an alternative embodiment, these objects are achieved by the invention in that the image acquisition module comprises a scan module having an optically transparent contact area, pixels of the subsurface being recordable as correspondingly graduated color and/or brightness values of the image data according to their distance from the contact area. One of the advantages of the invention is that for the pressure determination, the pressure measurement device can measure pressure by simple technical means, for example based on optical and/or capacitive recording and/or by using a “radiofrequency” sensor technology, the image acquisition module being for example a fingerprint sensor. In the case of RF sensor technology, for example, a radiofrequency signal is emitted by a sensor and corresponding signal reflections are measured. By using the radiofrequency signal, it is therefore possible to record ridges and grooves of the skin surface touching the contact area. Such fingerprint sensors represent a further possibility in addition to optical or capacitive technologies. In principle, an object is accordingly scanned i.e. sampled or analysed in a systematic, regular way. Therefore, for example on the basis of the same image data of a fingerprint or a partial fingerprint, pressure value parameters can be recorded simultaneously with biometric characteristics.
In an alternative embodiment, these objects are achieved by the invention in that the force exertable by using an elastically structured subsurface onto the contact area of a pressure measurement device is recorded by using a calibrated second measurement device, in that image data of the elastically structured subsurface of the object are recorded as correspondingly graduated color and/or brightness values according to their distance from the contact area by using an image acquisition module of the pressure measurement device, in that a stack memory of an integration module of the pressure measurement device is incremented on the basis of the color and/or brightness values of the image data, a corresponding pressure value parameter being generated by using a filter module on the basis of the stack memory level value, and the stack memory level value and the pressure value parameter allocated to it are transmitted as a value pair into the lookup table and/or transmitted as a calibration value pair into the correlation module of the pressure measurement device. This has the advantage inter alia that the pressure value parameters determined by using the calibrated second pressure measurement device correspond to absolute pressure values. These may either be stored as calibration value pairs in a lookup table or defined by using a correspondingly tuned correlation function. Calibration of the pressure measurement parameters may also be carried out individually or per user.
In particular, these objects are also achieved by the invention in that a coordinate acquisition device comprises a touch-sensitive contact area for recording planar x/y coordinate data of a subsurface, touching the contact area, of an object, and a coordinate acquisition module for generating corresponding signal data, in that the contact area is a component of a pressure measurement device, a corresponding pressure value parameter being generatable by using the pressure measurement device when an elastically structured subsurface of an object touches the contact area, in that the coordinate acquisition device comprises a filter module for generating z coordinate data as a function of the pressure value parameter, corresponding z coordinate data being allocatable to each possible pressure value parameter by using the filter module, and in that the coordinate acquisition device comprises a coordinate acquisition module for generating corresponding signal data as 3D coordinate data on the basis of the z coordinate data and the x/y coordinate data recorded by using an image acquisition module of the pressure measurement device. This has the advantage inter alia that, in contrast to the prior art, coordinate data of a three-dimensional space or 3D coordinate data can also be generated without the contact area touched by a subsurface of the object needing to have elastic properties. Movements of the object on the contact area in the x and y directions are in this case determined definitively by the physical dimensions of the contact area. In the z direction, i.e. mainly at right angles to the contact area, the size of the z coordinate is determined in particular by the elasticity of the structured object surface, the distance of the structures from the surface being recordable as pixels and the pixels being capable of having corresponding color and/or brightness values according to their distance from the contact area.
In another alternative embodiment, these objects are achieved by the invention in that the coordinate acquisition device comprises an interface module for generating control signals and/or data signals on the basis of the 3D coordinate data. Such an alternative embodiment has the advantage that the 3D coordinate data can correspondingly be transmitted as control signals and/or data signals to other modules by using the interface module. The interface module may inter alia be configured as a bus and/or parallel and/or serial interface.
In another alternative embodiment, these objects are achieved by the invention in that the filter module of the coordinate acquisition device comprises a lookup table, value pairs which respectively comprise a reference value and a correspondingly allocated pressure value parameter being storable in the lookup table, and in that the filter module comprises a comparison module for comparing a stack memory level value transmitted to the comparison module with the reference values of the lookup table, the corresponding z coordinate data being allocatable on the basis of the comparison in order to generate the z coordinate data by using the lookup table. This has the advantage inter alia that the assignment of corresponding z coordinate data to a pressure value parameter can be carried out rapidly by using the lookup table.
In another alternative embodiment, these objects are achieved in that the filter module of the coordinate acquisition device comprises a correlation module for allocating a stack memory level value, the stack memory level value transmitted to the correlation module, to the corresponding z coordinate data on the basis of at least one exponentiation and/or at least one multiplication and/or at least one addition factor, to thereby generate the corresponding z coordinate data. Such an alternative embodiment has the advantage that an exact correlation between the corresponding z coordinate data and a pressure value parameter is possible by using the correlation module. The correlation module may be embodied in hardware and/or software.
In particular, the objects are also achieved by the invention in that planar x/y coordinate data of a subsurface, touching the contact area, of an object are recorded by using a touch-sensitive contact area of a navigation input device, and a coordinate acquisition module as well as a timer module generate corresponding time-dependent signal data, in that the pressure measurement device comprises a timer and/or scheduler module for generating at least one timebase and/or corresponding time value parameters, in that planar x/y coordinate data can be recorded by using the image acquisition module of the pressure measurement device, and in that the navigation input device comprises an adder module for adding 3D coordinate data and time value parameters and for generating corresponding time-dependent 3D coordinate data. This has the advantage inter alia that navigation with the aid of four dimensions x, y, z and t is possible by using the navigation input device. For example, the sequence of 3D coordinate data within a particular time may be followed by using the navigation input device.
In another alternative embodiment, the navigation input device comprises an interface module for generating control signals and/or data signals on the basis of the time-dependent 3D coordinate data. Such an alternative embodiment has the advantage that the time-dependent 3D coordinate data may be transmitted inter alia via a bus and/or a line system to a display module, or that the data may be transmitted for further processing to a processor system or into a memory.
In particular, the objects are also achieved by the invention in that a user can be authenticated by using an authentication device, identified stored image data as reference image data of a fingerprint or a subregion thereof being comparable with image data, to be identified, of a further fingerprint or a subregion thereof, a corresponding authentication parameter being generatable as a function of the comparison, in that the pressure value parameter recorded by using a pressure measurement device can be correspondingly allocated to the image data of the first image to be identified, in that the pressure value parameter recorded by using a pressure measurement device can be correspondingly allocated to the image data of the further image, and in that the authentication device comprises a filter module for generating the authentication parameter on the basis of the match of the corresponding pressure value parameters and as a function of the match of the identified image data with the image data of the further image. This has inter alia the advantage that when identifying by using image data of a fingerprint, it is additionally possible to check whether the object touching the contact area corresponds to a fingerprint of a person or whether a copy of a fingerprint has merely been applied onto the contact area. In the latter case the copy, for example on a piece of paper or a film, has the corresponding elasticity properties so that the structure does not change substantially as a function of the force exerted onto the contact area. The pressure value parameter would change only insubstantially or not at all during an authentication process. This device therefore leads to increased authentication security.
In another alternative embodiment, these objects are achieved by the invention in that a filter module of the authentication device comprises a lookup table, value pairs which respectively comprise a reference value and a correspondingly allocated pressure value parameter being stored in the lookup table, and in that the filter module comprises a comparison module for comparing a stack memory level value transmitted to the comparison module with the reference values of the lookup table, the corresponding authentication parameter being allocatable on the basis of the comparison in order to generate the authentication parameter by using the lookup table. Such an alternative embodiment has the advantage that very rapid assignment of a corresponding pressure value parameter to a reference value takes place.
In particular, the objects are also achieved by the invention in that a user can be authenticated by using an authentication device, identified time-dependent x/y coordinate data of a subsurface, touching a touch-sensitive contact area, of an object, which are stored as signature data, being comparable with x/y coordinate data to be identified, and means for generating corresponding authentication parameters, in that the contact area is a component of a navigation input device, corresponding time-dependent 3D coordinate data being generatable by using the navigation input device when an elastically structured subsurface of the object touches the contact area, in that the authentication device comprises means for storing time-dependent 3D coordinate data as signature data, and in that the authentication device comprises a filter module for generating the authentication parameter on the basis of the comparison of the signature data with the recorded 3D coordinate data. This has the advantage inter alia that authentication of a user is achieved by a previously stored and identified signature being replicated, for example by using a finger on a fingerprint sensor. A signature may be an autograph, a geometrical figure and the like. A signature is characterised in that x, y, z coordinate data along the path of the signature are recorded and stored. In addition, a time value parameter may be allocated to the 3D coordinate data. The finger can be moved over the narrow fingerprint sensor while recording the signature, so that only slight movements are necessary.
In another alternative embodiment, these objects are achieved by the invention in that user-specific image data of a fingerprint and/or a subsurface of an object are allocated to a multiplicity of the recorded coordinate data by using the signature authentication method, and in that the recorded image data are compared with the identified reference image data, corresponding authentication parameters being generated if the comparison matches. Such an alternative embodiment has the advantage that image data recorded by using the image acquisition module can also be used for authentication by using a fingerprint, so that a combination of authentication by using a fingerprint and authentication by using a signature is possible.
In another alternative embodiment, these objects are achieved by the invention in that the authentication device comprises an interface module for generating control signals and/or data signals on the basis of the at least one authentication parameter. Such an alternative embodiment has the advantage that the authentication parameters can correspondingly be transmitted as control signals and/or data signals to other modules by using the interface module. The interface module may inter alia be configured as a bus and/or parallel and/or serial interface.
In another alternative embodiment, these objects are achieved by the invention in that the authentication device comprises means for determining subregions of subsurfaces of an object, and in that the authentication device comprises means for comparing at least two subregions for a match. Such an alternative embodiment has the advantage that only small regions of a subsurface of an object, for example a finger pad, have to be recorded by using the authentication device. The authentication process can therefore be accelerated.
In particular, the objects are also achieved by the invention in that, by using a command input device, planar coordinate data stored as specified command pattern data can be compared for a match with x/y coordinate data of a subsurface, touching a touch-sensitive contact area and moved over it, of an object, and comprises means for generating corresponding command parameters, in that the contact area is a component of a pressure measurement device, in that planar coordinate data can be recorded by using an image acquisition module of the pressure measurement device, in that corresponding pressure value parameters can be recorded by using the pressure measurement device, in that the command input device comprises a filter module for allocating corresponding pressure value parameters to a multiplicity of the planar coordinate data, in that the command input device comprises a filter module for generating the command parameter on the basis of the comparison of the planar coordinate data and/or the pressure value parameters of the specified command pattern data with the recorded planar coordinate data and/or the pressure value parameters, and in that the command input device comprises an interface module for generating control signals and/or data signals on the basis of the at least one command parameter. This has the advantage inter alia that commands or instructions recorded by using the command input device can be compared with commands or instructions stored as reference data and/or reference patterns and transmitted as command parameters to a processor module by using the interface module if there is a match. This makes it possible for a user to transmit simple instructions to the corresponding device on the basis of a library of instructions.
In particular, the objects are also achieved by the invention in that at least one symbol can be selected from a multiplicity of symbols representable on a display module by using interaction with an object and an input unit, a cursor element being positioned on the display module by the interaction, the symbol being selected and a data signal being generated and transmitted on the basis of the position of the cursor element, in that the input unit is embodied as a contact area of a pressure measurement device having an image acquisition module, planar coordinate data being recorded by using the pressure measurement device, in that corresponding pressure value parameters are recorded by using the pressure measurement device, the cursor element being positioned as a function of the x/y coordinate data on the symbol to be selected, in that the chosen symbol is selected on the basis of the pressure value parameter generated by using the pressure measurement device, and in that the data signal is generated and transmitted by using a filter module of the pressure measurement device on the basis of the selected symbol. This has inter alia the advantage that, for example in the case of a security token consisting of a display module and a fingerprint sensor, a dialogue is made possible between a user and the security token. If numbers from 0 to 9, a symbol for “correction” or “clear”, a symbol for “input confirmation” or “enter” and a cursor element are represented on the display module, then the user can position the cursor element on the symbol to be selected with a finger on the image acquisition module as a function of the x/y position of his or her finger on the contact area, and can select the corresponding symbol by pressing the finger onto the contact area. This makes it possible to input for example a personal identification number (PIN).
In particular, the objects are also achieved by the invention in that at least one symbol can be selected from a multiplicity of symbols representable on a display module by using interaction with an object and an input unit, a cursor element being positioned on the display module by the interaction, the symbol being selected and a data signal being generated and transmitted on the basis of the position of the cursor element, in that the input unit is embodied as a contact area of a pressure measurement device having an image acquisition module, planar coordinate data being recorded by using the pressure measurement device, in that corresponding pressure value parameters are recorded by using the pressure measurement device, the cursor element being positioned as a function of pressure value parameter on the symbol to be selected, in that the symbol is selected on the basis of the x/y coordinate data generated by using the pressure measurement device, and in that the data signal is generated and transmitted by using a filter module of the pressure measurement device on the basis of the selected symbol. This has inter alia the advantage that a symbol and/or a number can be selected from a multiplicity of symbols and/or numbers arranged on a line so that the cursor element is positioned according to the pressure value parameter on the symbol through exertion of pressure onto the contact area by an object and is selected by moving the object in the x/y direction.
At this point, it should be mentioned that in addition to the methods, the present invention also relates to devices for carrying out corresponding methods.
These and other features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying drawings where:
a shows a schematic representation of a subset of pixels of an elastically structured subsurface, touching a contact area, of an object when the object exerts a small force onto the contact area;
b shows a schematic representation of a subset of pixels of an elastically structured subsurface, touching a contact area, of an object when the object exerts an increased force onto the contact area;
a shows a schematic representation of a display unit for the output of symbols in a matrix representation and the interaction of a user by using his or her finger on an input unit;
b shows a schematic representation of a display unit for the output of symbols in a wheels type representation; and
Herein, identical reference numerals are used, where possible, to designate identical elements that are common to the figures. The images in the drawings are simplified for illustrative purposes and are not depicted to scale.
pwr{circumflex over (=)}h2 h2=a·b,
m
h
2
=b·(a+b),
m
v
2
=a·(a+b),
m
h
2
+m
v
2=(a+b)2. Formula 1: Calculation of a pressure value indicator (“widening ridge” method).
A pressure value parameter may for example also be determined with the aid of frequencies of color and/or brightness values of the pixels of a subregion of a subsurface 711. In the background art, fingerprint sensors are for example known which make the aforementioned brightnesses available as a so-called pixel histogram. In order to determine a pressure value parameter, frequencies of darker pixels are to be compared with frequencies of brighter pixels. A threshold value may be employed for determining the pressure value parameter, so that for example a contact signal can be generated. In this case, Pph corresponds to a resulting pressure value indicator, th to a threshold value and k to a number variable for forming a sum. In general, the calculation may also be represented as dividing the sum of all color and/or brightness values of “darker” pixels by the sum of the color and/or brightness values of the “brighter” pixels, the pixels having been determined for example by using a fingerprint sensor:
The determination of the pressure value parameter may be carried out in software and/or in hardware. The filter module denoted by the reference 13 may comprise a lookup table, value pairs which respectively comprise a reference value and a correspondingly allocated pressure value parameter being stored in the lookup table. The filter module 13 may comprise a comparison module for comparing a stack memory level value transmitted to the comparison module with the reference values of the lookup table, the corresponding pressure value parameter being allocatable on the basis of the comparison in order to generate the pressure value parameter by using the lookup table. The filter module 13 may also comprise a correlation module for allocating a stack memory level value, transmitted to the correlation module, to a pressure value on the basis of at least one exponentiation and/or at least one multiplication and/or at least one addition factor, the corresponding pressure value parameter being generatable on the basis of the correlation. This correlation module may for example be implemented as a “fit function” in hardware and/or software. The pressure measurement device 1 may comprise a processor, which can calculate and carry out in particular the recording and storage of image data, and the calculation of the pressure value parameter and filter functions. The memory module 14 may be an integrated component of a processor or microprocessor. The pressure measurement device may comprise an interface module 19 for generating control signals and/or data signals on the basis of the pressure value parameter. In this case, the pressure value parameter may for example be transmitted to a display module, an acoustic output unit or an alarm signal generation unit.
In
In
In
Identified time-dependent x/y coordinate data of a subsurface, touching a touch-sensitive contact area 111, of an object 7, which are stored as signature data, can also be compared with x/y coordinate data to be identified, and the authentication device comprises means for generating corresponding authentication parameters. The contact area 111 is a component of a navigation input device 3, corresponding time-dependent 3D coordinate data being generatable by using the navigation input device 3 when an elastically structured subsurface 711 of the object 7 touches the contact area 111. The authentication device 4 comprises means 42 for storing time-dependent 3D coordinate data as signature data. The authentication device 4 comprises a filter module 41 for generating the authentication parameter on the basis of the comparison of the signature data with the recorded 3D coordinate data. The filter module 41 of the authentication device 4 comprises a lookup table, value pairs which respectively comprise a reference value and a correspondingly allocated pressure value parameter being stored in the lookup table. The filter module 41 comprises a comparison module for comparing a stack memory level value transmitted to the comparison module with the reference values of the lookup table, the corresponding authentication parameter being allocatable on the basis of the comparison in order to generate the authentication parameter by using the lookup table. The authentication device 4 comprises an interface module 19 for generating control signals and/or data signals on the basis of the at least one authentication parameter. The authentication device 4 comprises means for determining subregions 7111 of subsurfaces 711 of an object 7. The authentication device 4 comprises means for comparing at least two subregions 7111 for a match.
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Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
Number | Date | Country | Kind |
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07005268.3 | Mar 2007 | EP | regional |
The present patent application claims priority to the Patent Cooperation Treaty Application with the Serial No. PCT/EP2008/000334, that was filed on Jan. 17, 2008, which itself claims priority to the European Patent Application with the Serial No. EP 07005268.3 that was filed on Mar. 14, 2007, all the contents thereof being herewith incorporated by reference.
Number | Date | Country | |
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Parent | PCT/EP08/00334 | Jan 2008 | US |
Child | 12559282 | US |