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Non-contact optical imaging system for biometric identificationNon-contact optical imaging system for biometric identification description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070035718, Non-contact optical imaging system for biometric identification. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a continuation of, and claims the priority benefit of, co-pending U.S. application Ser. No. 10/233,031 filed Aug. 30, 2002. BACKGROUND OF THE INVENTION [0002] A. Field of the Invention [0003] The present invention relates to a non-contact optical imaging system for biometric identification. [0004] B. Description of Related Art [0005] There is a great need in today's age of electronic information for increased security and positive identification. For example, this includes reliable identification of purchasers at vendor sites and over the internet, identification of participants in other financial transactions, and identification in access control and anywhere sensitive information must be handled or transmitted. The growing field of biometrics provides one technological answer to this need for reliable identification. Biometric technologies measure and characterize some unique feature of a person's anatomy, which is then used to identify that person. [0006] A number of biometric identification devices already exist. These include fingerprint readers, hand geometry readers, iris imagers, retinal cameras, voice recognition, and face recognition devices. Devices that are more esoteric include fingernail ridge identification and cameras that image the vascular patterns in the earlobe. Probably the most promising, best developed, and most common of these biometric devices are fingerprint readers. [0007] Each of these biometric identification devices has its own problems and strong points. Important features of any biometric device are user comfort, with resulting willingness to use; low false rejection rate; low false acceptance rate; cost; size; speed of operation; and robustness in a wide range of operating environments. Fingerprint readers represent a good mix of all of these features, especially user acceptance. [0008] There are two basic types of fingerprint readers available today, ones with (1) direct-reading sensors and (2) optical sensors. All direct-reading sensors, and all but a few rare specialized optical readers, require users to press the pad of their finger firmly onto a "platen" to be read. In the case of direct readers, the platen is the surface of the sensor itself. The device essentially makes a contact print of the finger surface, relying on the principle that the higher ridges of the finger will touch, or be closer to the surface, of the sensor than the valleys of the fingerprint. Several variations on this technology are currently available. [0009] On the other hand, the vast majority of existing optical readers have a prism or other glass (or possibly plastic) surface on which users place their fingers, and through which the image of the fingerprint is taken. These devices rely on changes in the reflectivity at the platen surface caused by contact with regions of the finger surface to produce high contrast images of the ridges in the fingerprint. The reflectivity changes are due to the difference and discontinuity in the refractive index at the surface between the platen and air. [0010] When a finger (or any object with a refractive index slightly higher that that of air) is placed in intimate contact (including, possibly, by wetting) with the platen surface the reflectivity at that location will be reduced. In principle only the high points (ridges) of the fingerprint will make intimate contact with the platen surface and will therefore appear darker than the valleys. The illumination of the platen surface is designed to maximize this effect. [0011] Contact optical biometric identification devices have inherent problems, including large variations in the print pattern depending on finger moistness or oiliness, variations with finger pressure, poor prints or missing sections of the print with dry or overly wet fingers, loss of contrast due to residue, or latent prints left on the platen from prior use. In addition, there is also the security risk of identity theft due to the possibility of a user lifting any latent prints. Many of the problems with optical readers are also present with direct reading sensors because of the need to place the finger onto the platen. In addition, other problems with the direct-reading sensors include fragility (breaking when an object is dropped on the necessarily thin platen), damage due to electrostatic discharge, and high cost. SUMMARY OF THE INVENTION [0012] The present invention is a new approach to optical reader technology. For its primary physical contrast mechanism, it relies on specular reflection directly from the object surface, rather than relying on internal reflection. This gives the invention the distinct advantage of non-contact biometric image acquisition, freeing it from most of the problems with current contact optical and direct reader technology. In addition, the invention is uniquely based on low cost and proven optical image sensors and therefore has the market driven advantage in both price and resolution. It also has no susceptibility to electrostatic discharge, works well regardless of the user's finger moistness or dryness, and has no print variation due to finger pressure. In fact, one of its most important advantages is that no pressure is required to get a good print. [0013] The preferred embodiment of the invention requires a user to place a finger over an opening in the housing to take the print, but other embodiments allow an entirely non-contact model for use in sterile or other special environments. A notable additional advantage of the invention is that it can be used with other regions of the skin surface other than fingertips for user identification, such as a knuckle or an elbow. This would be useful, for example, in special cases where users either do not have or do not have use of their fingers. [0014] In summary, the invention is an optical system for imaging the features, ridges, and height variations of an object by exploiting the properties of specular reflection of light to maximize the contrast of the features, ridges, and height variations. The invention comprises a light source (such as a light emitting diode), a means for positioning the object to be imaged (such as a physical rest or a position detector), a means for shaping the wave front of the light emitted from the light source so as to cause it to illuminate the object so as to produce a strong specular reflection over the entire surface of the object (such as mirror or lenses), a means for focusing an image of the object using the reflected light (such as lenses or mirrors), and an image sensor positioned so that the light reflected from the object creates the image on it (such as CCD or CMOS image sensors). BRIEF DESCRIPTION OF THE DRAWINGS [0015] FIG. 1 is a perspective view of an embodiment of the invention designed for imaging fingerprints. [0016] FIG. 2 is a box-schematic drawing of an embodiment of the invention designed for imaging fingerprints. [0017] FIG. 3 is a cross-section view of an embodiment of the invention designed for imaging fingerprints. FIG. 4 is a schematic drawing of an embodiment of the invention designed for imaging fingerprints. [0018] FIG. 5 shows examplar fingerprint images taken by the invention. DESCRIPTION OF THE INVENTION [0019] The invention produces high quality, high contrast, uniform, and consistent images of the surface features, such as characteristic ridges, of a finger or other biometric object. The basic physical property upon which the reader depends is the use of specular reflection of light to maximize the contrast of features, ridges, and height variations. Optionally, the invention uses a polarizer that filters and thereby enhances the specular reflection from the surface of the object. Optionally, the invention can also include pre-processing means for adjusting image brightness, contrast, and magnification. Continue reading about Non-contact optical imaging system for biometric identification... Full patent description for Non-contact optical imaging system for biometric identification Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Non-contact optical imaging system for biometric identification patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Non-contact optical imaging system for biometric identification or other areas of interest. ### Previous Patent Application: Contact lithography apparatus, system and method Next Patent Application: Plastic packaging having a marker material Industry Class: Optics: measuring and testing ### FreshPatents.com Support Thank you for viewing the Non-contact optical imaging system for biometric identification patent info. 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