Fingerprint sensors

Abstract

A sensor for detecting fingerprints is provided having first and second substrates, a two-dimensional array of sensing elements formed on the first substrate, and a plurality of thin-film transistors or TFTs for controlling the sensing elements at pixel location along the array. Each of the sensing elements detects one of electrical signals (e.g., capacitance, resistance, or impedance), temperature, or light via one of the first or second substrates representative of one or more fingerprints. The top of the second substrate or the bottom of the first substrate may provide a platen upon which one or more fingers can be disposed. The sensor may be utilized in a fingerprint scanner having one or more processors driving sensing elements or reading from sensing elements analog signals representative of one or more fingerprints, and generating an image representative of the one or more fingerprints from the analog signals.

1 . A sensor for detecting one or more fingerprints comprising:
 a first substrate and a second substrate;   a two-dimensional array of sensing elements formed at pixel locations on said first substrate; and   a plurality of thin-film transistors for controlling said sensing elements at each of said pixel locations, wherein each of said sensing elements detects one of electrical signals, temperature, or light via one of said first substrate or said second substrate representative of one or more fingerprints.   
     
     
         2 . The sensor according to  claim 1  wherein said second substrate has a surface opposite said first substrate, and said second surface provides a platen surface for placement of one or more fingers, and said two-dimensional array of sensing elements receive said one of electrical signals, temperature, or light via said second substrate representative of one or more fingerprints. 
     
     
         3 . The sensor according to  claim 1  wherein said first substrate has a first surface and a second surface, and said sensing elements are formed on a first surface, and said second surface provides a platen surface for placement of one or more fingers, and said two-dimensional array of sensing elements receives said one of electrical signals, temperature, or light via said second surface representative of one or more fingerprints. 
     
     
         4 . The sensor according to  claim 1  wherein said sensing elements of said array are at least light sensing elements, and said sensor further comprises an illuminator providing light to said first and second substrates, and a plurality of said light sensing elements detect reflected light representative of one or more fingerprints. 
     
     
         5 . The sensor according to  claim 4  further comprising a prism array for receiving light from said illuminator and one or more of refracting or diffracting said light received to said first and second substrates. 
     
     
         6 . The sensor according to  claim 1  wherein said sensing elements of said array are at least light sensing elements, and said sensor further comprises an array of light sources between said first substrate and said second substrate for transmitting light via said second substrate, and a plurality of said light sensing elements detect reflected light representative of one or more fingerprints via said second substrate. 
     
     
         7 . The sensor according to  claim 1  further comprising one or more processors, each of said thin-film transistors controls said one or more of said sensing elements responsive to said one or more processors to enable said one or more processor to one or more of driving said one or more of said sensing elements or reading from said one or more sensing elements analog signals representative of one or more fingerprints, and generates an image representative of said one or more fingerprints responsive to said analog signals. 
     
     
         8 . The sensor according to  claim 7  wherein at least one of said one or more of said processors is part of a computer system. 
     
     
         9 . The sensor according to  claim 1  wherein said electrical signals are one of capacitance, resistance, or impedance. 
     
     
         10 . The sensor according to  claim 1  wherein said sensing elements of said array are at least light sensing elements, and said first substrate has a first surface and a second surface, and said sensing elements are formed on a first surface, and said second substrate has a third surface opposite said first substrate, and said sensor further comprises an optical element disposed upon one of said second surface or said third surface, in which said optical element has a fourth surface and a fifth surface, said fourth surface provides a platen surface for placement of one or more fingers, and light when received by said optical element via said fifth surface is directed to said fourth surface, and said plurality of said light sensing elements detect reflected light representative of one or more fingerprints via said disposed upon one of said second surface or said third surface upon which said optical element is disposed. 
     
     
         11 . The sensor according to  claim 10  wherein said optical element is a prism. 
     
     
         12 . The sensor according to  claim 11  wherein said prism is a right angle prism and said fifth surface is perpendicular to said second surface or said third surface upon which said optical element is disposed. 
     
     
         13 . The sensor according to  claim 11  wherein said fourth surface of said prism providing said platen is along a plane parallel to the plane of said sensing elements of said array. 
     
     
         14 . The sensor according to  claim 10  said optical element provides said second substrate. 
     
     
         15 . The sensor according to  claim 1  wherein said sensing elements of said array are only light sensing elements for receiving light via one of said first substrate or said second substrate representative of one or more fingerprints. 
     
     
         16 . The sensor according to  claim 1  wherein said sensing elements of said array are only electrical sensing elements for receiving electrical signals via one of said first substrate or said second substrate representative of one or more fingerprints. 
     
     
         17 . The sensor according to  claim 1  wherein said sensing elements of said array are only temperature sensing elements for receiving temperature signals via one of said first substrate or said second substrate representative of one or more fingerprints. 
     
     
         18 . The sensor according to  claim 1  wherein said sensing elements of said array represent a first plurality of light sensing elements for detecting light representative of one or more fingerprints, and a second plurality of electrical sensing elements for receiving electrical signals representative of one or more fingerprints or for detecting liveliness of said one or more fingers. 
     
     
         19 . The sensor according to  claim 1  wherein at each said pixel location along said array has a plurality of sensing elements for sensing different types and each of said plurality of sensing elements is coupled to a same one of said TFT at the pixel location 
     
     
         20 . The sensor according to  claim 1  wherein a plurality of said sensing elements for sensing different types of characteristics are uniformly distributed at different pixel locations along said array. 
     
     
         21 . The sensor according to  claim 1  wherein a plurality of said sensing elements for sensing different types of characteristics are non-uniformly distributed at different pixel locations along said array. 
     
     
         22 . The sensor according to  claim 1  wherein said sensing elements of said array are of different groups, in which each group of sensing elements has a different mode of operation. 
     
     
         23 . The sensor according to  claim 1  wherein said sensing elements of said array are at least light sensing elements, and said sensor further comprising means for providing illumination of collimated or nearly collimated light illumination, in which a plurality of said light sensing elements detect reflected part of said collimated or nearly collimated light illumination representative of one or more fingerprints. 
     
     
         24 . The sensor according to  claim 1  wherein said sensing elements of said array are at least light sensing elements, and said sensor further comprising means for providing illumination, in which a plurality of said optical sensing elements detect reflected part of said illumination representative of one or more fingerprints via said second substrate, and said illumination of one or more wavelength which reduce diffraction in said light received by said plurality of said optical sensing elements. 
     
     
         25 . The sensor according to  claim 1  wherein said second substrate represents a cover formed upon the first substrate. 
     
     
         26 . The sensor according to  claim 1  wherein said sensing elements of said array are at least light sensing elements, and said sensor further comprises means for providing polarized illumination to enable a plurality of said light sensing elements to detect reflected part of said illumination representative of one or more fingerprints. 
     
     
         27 . The sensor according to  claim 1  wherein said array has one or more other sensing elements for radio frequency sensing. 
     
     
         28 . A method for detecting one or more fingerprints comprising:
 providing a two-dimensional array of sensing elements at pixel locations on said first substrate, in which each of said sensing elements detects one of electrical signals, temperature, or light via one of said first substrate or a second substrate facing said first surface representative of one or more fingerprints; and   a plurality of thin-film transistors for controlling said sensing elements at each of said pixel locations.   
     
     
         29 . A system for detecting one or more fingerprints comprising:
 a first substrate and a second substrate;   a two-dimensional array of sensing elements formed at pixel locations on said first substrate;   a plurality of thin-film transistors for controlling said sensing elements at each of said pixel locations, wherein each of said sensing elements detects one of electrical signals, temperature, or light via one of said first substrate or said second substrate representative of one or more fingerprints; and   one or more processors, each of said thin-film transistors controls said one or more of said sensing elements responsive to said one or more processors to enable said one or more processor to one or more of driving said one or more of said sensing elements or reading from said one or more sensing elements analog signals representative of one or more fingerprints, and generates an image representative of said one or more fingerprints responsive to said analog signals.   
     
     
         30 . The system according to  claim 29  wherein said sensing elements of said array are at least light sensing elements, and said sensor further comprising means for providing illumination, in which a plurality of said optical sensing elements detect reflected part of said illumination representative of one or more fingerprints via one or said first or second substrates. 
     
     
         31 . A device for capturing an image of an object comprising:
 a first substrate and a second substrate;   a two dimensional array of photoreceptors and TFTs in which each photoreceptor is controlled by one of said TFTs, in which one of said first and second substrates provides a platen surface for capturing an image of an object when disposed upon said platen surface and illumination is provide from within said first and second substrates or below said first and second substrates to enable reflected light representing said object to be captured onto said two dimensional array of photoreceptors.   
     
     
         32 . The device according to  claim 31  wherein said object is a document, a signature, a bar code, or one or more fingers.