Image analysis – Applications – Personnel identification
Reexamination Certificate
1998-04-24
2002-12-31
Mehta, Bhavesh (Department: 2611)
Image analysis
Applications
Personnel identification
C382S127000, C345S156000, C345S045000
Reexamination Certificate
active
06501846
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to relief object image generators, and more particularly, to use of relief object image generators with computer systems.
BACKGROUND OF THE INVENTION
Systems for generating images of relief objects are known. Relief objects are objects having a surface with features typically formed by areas and sections lying both within and outside a single two-dimensional geometric plane. A common relief object imaged by known technology is the surface of the human finger which contains ridges and valleys forming a fingerprint. These known systems include a platen to which a relief object is pressed to expose the ridges (areas of the fingerprint which contact the platen) and valleys (areas of the fingerprint which do not contact the platen) of the relief object to imaging equipment. The platen is illuminated by a light source. In many relief object imaging systems, the light from the light source is passed through a collimator before it illuminates the platen. The light is typically coupled through a right-angle prism to the platen at or near an angle corresponding to Total Internal Reflection (TIR). The frustration of TIR and the resulting absorption of light occurs at the ridges of the relief object where the relief object actually makes contact with the platen, thereby creating dark areas corresponding to these ridges. TIR remains undisturbed at the valleys of the relief object where no physical contact with the relief object occurs so illuminated patterns corresponding to the valleys are generated. Thus, light from the light source is modulated by the structural features of the relief object pressed against the platen and this modulated light is transmitted through the platen to an optical system. The optical system is usually comprised of lenses and other optical treating components. The optically treated, modulated light then impinges on a sensor array which converts the optical energy into electrical energy. The intensity at each element of the sensor array is typically converted to a digital value and the values for the array elements may then be processed by a computer for classification or verification of the relief object.
These known relief object imaging systems have a number of disadvantages. For one, each requires a light generating source which must be located at a distance from the platen so that a substantial portion of the platen surface is illuminated by the light source. Additionally, the optically treating elements are typically placed at a distance and angle from the platen to receive the reflected light from the platen. To optimize the benefits of the optical element processing, the optical treating elements must be located at distances from the platen where light rays converge or other known optical physical phenomena occur. Thus, the geometry of known relief object imaging systems impose size constraints which limit the applications for known relief object imaging systems.
Another disadvantage of known imaging systems are distortions of the reflected image. For example, the platen and sensor array in a typical relief object imaging system are tilted to maintain good focus while also maintaining platen illumination near the TIR angle. This tilting causes a type of distortion known as a keystone distortion, which is an apparent shortening of one side of the image due to an asymmetrical magnification factor imposed by this tilt angle. The resulting optical aberration causes the relief object image generator to create a trapezoidal image from a square object. Frequently, this distortion is reduced by interposing optical elements between the sensor array and the platen. However, the interposing of additional optical treating elements exacerbates the geometric constraints for the system and further impacts the applications in which the system may be used.
Known relief object image generating systems are also sensitive to ambient light entering the platen from the surface on which the relief object is placed. Additionally, the presence of an excessive amount of moisture or oil on the relief object alters the modulation of the light by the relief object and may further degrade the image of the relief object in such systems. Likewise, an exaggerated absence of moisture and other fluids in a relief object, such as a fingerprint, may also alter the light modulation produced by the relief object and degrade the image of the relief object. Also, systems which are engineered to address image degradation caused by excessive moisture may not adequately correct degradation caused by excessively dry relief objects and vice versa.
Other known relief object image generators which are not based on light emission principles replicate fingerprint images using direct capacitive coupling between the finger and an electrical sensor. These devices typically suffer from sensitivity to electrostatic discharge environments and can typically be severely damaged through abrasion. The greatest disadvantage with these devices is the cost of these relief object image generators which render the wide scale integration of these devices into computer systems economically impractical.
Computer security is an increasingly important concern as computers become smaller and personal computer inter-connectivity proliferates. The mobility and enhanced capabilities of computers provide computational resources at sophisticated levels as well as at previously unknown locations and situations. These advancements make unauthorized computer access more likely because effective physical control is more difficult to exercise over small portable computers than stationary computers and open networks like the Internet make logical access to computers easier. One way to frustrate the purpose of computer thieves is to deny them, or the persons to whom they sell the computers, the ability to use the computer. Most computer access control systems use a password or other secret tokens that an authorized user enters to activate a computer system. However, most computer thieves can disable password protection or similar security access features so the computer may be used by someone other than an authorized person. While there are known systems for limiting access to valuable resources by identifying authorized persons with fingerprint imaging systems, known relief object image generators do not possess physical geometrical dimensions which render them compatible with laptop computers and the like for reasons discussed above.
Associated with the increasing need to enhance computer access security is the need to accomplish much of the typical computer/user interface functionality in a more compact, cost effective and ergonomically efficient manner. That is, as the footprint of portable computers decreases, the area available for the keyboard, function keys and cursor control devices also decreases. Thus, a need is arising for a cursor controller that requires less area of a keyboard than known touchpads or that can be integrated with other functional components of a user's keyboard.
What is needed is a relief object imaging system for performing security and access control functions that may be incorporated in different types of computer systems used in a variety of applications.
What is needed is a device that integrates the control of function keys with the function of a cursor control device.
SUMMARY OF THE INVENTION
The above identified limitations and disadvantages of previously known computer access control devices are overcome by a system made in accordance with the principles of the present invention. A computer access control system made in accordance with the principles of the present invention includes a relief object generator which is comprised of a single electrode electroluminescent device coupled to an alternating current source to generate an image corresponding to a relief object placed against the relief object image generator, a sensor array for receiving the generated image and converting the image to electrical signals, a memory for storing image data cor
Cole Andrew
Derwitsch Fredric F.
Dickinson Alexander G.
Hadjiabadi Shahin
Marteney Steven J.
Eldredge, Esq. John
Ethentica, Inc.
Mehta Bhavesh
Stradling Yocca Carlson & Rauth LLC
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