Piezoelectric surface pressure input panel
First Claim
1. A surface pressure input panel for detecting surface irregularities in an object comprising:
- a pressure sensitive sheet having first and second groups of electrode lines formed thereon and intersecting with each other to form intersection portions; and
an element coupled to the sheet for vibrating the sheet at a given reference frequency, the sheet vibrating locally at frequencies that differ from the reference frequency when the surface irregularities of the object are pressed against corresponding portions of the sheet, the sheet being adapted to generate electric signals that represent the local vibration frequencies and to apply the electrical signals to the first and second groups of electrode lines so that a relative location of each generated electrical signal can be determined.
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Accused Products
Abstract
An active matrix surface pressure input panel comprises a piezoelectric sheet having electrode lines formed thereon and coupled to a piezoelectric body for vibrating the sheet at a given reference frequency. When an object having surface variations, such as a fingertip, is pressed against the sheet, corresponding underlying portions of the sheet vibrate at frequencies that differ from the reference frequency. The local vibration frequencies are detected by electrode lines applied to opposing sides of the sheet, preferably in an X-Y grid, so that the relative locations of the sheet from where the detected signals emanate can be determined. The surface pressure input panel exhibits high definition over a relatively large detection area so that complicated surfaces, such as fingerprints, can be accurately detected and reproduced.
187 Citations
20 Claims
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1. A surface pressure input panel for detecting surface irregularities in an object comprising:
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a pressure sensitive sheet having first and second groups of electrode lines formed thereon and intersecting with each other to form intersection portions; and an element coupled to the sheet for vibrating the sheet at a given reference frequency, the sheet vibrating locally at frequencies that differ from the reference frequency when the surface irregularities of the object are pressed against corresponding portions of the sheet, the sheet being adapted to generate electric signals that represent the local vibration frequencies and to apply the electrical signals to the first and second groups of electrode lines so that a relative location of each generated electrical signal can be determined. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for use in mapping physical surface irregularities of an object, the apparatus comprising:
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a piezoelectric sheet adapted to generate electric signals at a multiplicity of areas distributed over the sheet, the signals representing local vibration frequencies at the areas of the sheet; means for vibrating the piezoelectric sheet at a given reference frequency; and detecting means for use in sensing the signals and determining the relative locations of the areas where the electrical signals are sensed; whereby the local vibration frequencies differ from the reference frequency when pressure is applied to corresponding portions of the piezoelectric sheet so that the surface irregularities can be mapped on the basis of the generated electrical signals and the relative locations of the corresponding portions of the sheet. - View Dependent Claims (11, 12, 13, 14)
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15. An apparatus for use in mapping physical surface irregularities of an object, the apparatus comprising:
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a touch panel including a piezoelectric sheet, first and second groups of electrode lines on opposed, first and second surfaces of the piezoelectric sheet forming intersection portions where the electrode lines of the first and second groups cross, the sheet being adapted to generate electric signals at the intersection portions that represent local vibration frequencies of the sheet and to apply the generated electric signals to the electrode lines, and an element coupled to the sheet for vibrating the piezoelectric sheet at a given reference frequency, whereby the local vibration frequencies differ from the reference frequency when pressure is applied to corresponding portions of the sheet; an oscillator operatively coupled to the element for vibrating the element at the reference frequency; and a detection circuit operatively coupled to the first and second groups of electrode lines for sensing the generated electric signals and determining the relative locations of the intersection portions where the signals are generated and thereby enable a reconstitution of the surface irregularities of the object. - View Dependent Claims (16, 17)
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18. A method for detecting a fingerprint pattern from a fingertip comprising the steps of:
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vibrating a piezoelectric sheet at a given reference frequency; pressing the fingertip against the sheet such that surface contours on the fingertip subject portions of the sheet to differing pressures to generate local vibration frequencies at the sheet portions which are responsive to the applied pressures; detecting the local vibration frequencies; and determining a relative location of the sheet portions where the local vibration frequencies are detected; whereby the fingerprint pattern can be recreated by correlating the local vibration frequencies with the relative locations of the sheet portions. - View Dependent Claims (19, 20)
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Specification