Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1999-03-10
2001-03-20
Lee, Michael G (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S449000, C235S494000, C235S468000
Reexamination Certificate
active
06202929
ABSTRACT:
TECHNICAL FIELD
The invention relates to the acquisition of encoded information, particularly barcode, that is written in a differentially conductive pattern and can be concealed from view within an envelope or other layered structure.
BACKGROUND
Much of bulk return mail is processed with at least some manual handling, especially when it contains orders. Once cut open, the envelopes are generally emptied by hand; and information from their contents is keyboarded, optically scanned, or otherwise entered into a computer. The required steps of opening the envelopes, separating their contents, and entering relevant data are expensive and time consuming. Also, data entry is subject to error, especially when information printed on the envelopes must be linked to information from their contents.
Outgoing bulk mail is also subject to sorting and other processing errors that are difficult to detect; because once sealed, their contents are concealed from view. For example, inserts containing confidential information can be placed in the wrong envelopes addressed to persons who become privy to private information of others. Many different approaches have been used to see through the envelopes and read their contents without opening them but problems plague each.
U.S. Pat. No. 5,522,921 to Custer proposes use of x-rays for reading envelope contents that are printed with special x-ray opaque materials. The x-rays penetrate the envelopes and their contents except where blocked by the special materials. A resulting shadow pattern is detected by an x-ray reading device. However, the special materials add expense and limit printing options, and the x-rays pose health risks that are difficult to justify for these purposes.
U.S. Pat. No. 5,288,994 to Berson proposes using infrared light in a similar manner to read the contents of sealed envelopes. A light source directs a beam of the infrared light through the envelopes to an optical detector that records a shadow pattern caused by different absorption characteristics between conventional inks and the paper on which they are printed. However, such filled envelopes make poor optical elements for transmitting images, even for transmissions in the infrared spectrum. Paper does not transmit the infrared images very efficiently. Irregularities in the surfaces, spacing, layering, and materials of the envelopes and their contents cause significant aberrations that can greatly diminish resolution of the images. Also, overlays of printed material on the envelopes and their contents are difficult to separate, and printed backgrounds can reduce contrast.
Except for differences in wavelength, these prior approaches are analogous to shining a flashlight through one side of an envelope in the hope of reading darker printed matter through the envelope's opposite side. X-rays penetrate paper very easily but are dangerous and require special materials to stop them. Near infrared wavelengths transmit poorly through paper, and their images are subject to aberration from optical inconsistencies and to obscuration from printed overlays or backgrounds.
U.S. Pat. No. 5,811,792 by two of the present co-inventors, Verschuur and Mitchell, Jr., proposes a combination of microwave heating and infrared viewing to access the contents of sealed envelopes. Microwave energy differentially heats conductive or dielectric patterns in the contents, and infrared detectors record thermal images of the patterns conducted to the envelopes' surfaces.
U.S. Pat. No. 5,621,200 to Irwin, Jr. et al. discloses an electronic validation system for scratch-off lottery tickets. A conductive ink containing a pattern of resistors is printed as a portion of the scratch-off material or underlying play indicia. Capacitors couple the printed resistor circuits to an electronic verification machine to verify electronic signature patterns of the resistor circuits. The electronic signatures are comparable to predetermined standards, but they do not contain information encoded in conventional formats that can be read as alphanumeric characters. Also, each ticket must be tested one at a time at a predetermined position within the verification machine.
U.S. Pat. No. 3,519,802 to Cinque et al. discloses an early attempt at authenticating credit cards with internally encoded data. Conductive plates are arranged in a pattern; and their presence, absence, or proximate orientation is detected by a capacitance sensor. However, the detection system requires the conductive plates to be bent into two offset planes that complicate manufacture and are not readily applicable to thinner substrates such as sheet materials normally enclosed by envelopes.
U.S. Pat. No. 4,591,189 to Holmen et al. discloses a more recent example of a credit card verification system in which a light-transmitting authenticating layer is sandwiched between two anti-reflective film layers. The authenticating layer is preferably vacuum deposited, such as by sputtering, but can also be formed by a printed layer of conductive ink. The impedance, conductance, or capacitance of the authenticating layer can be detected, though capacitance is not recommended for detecting discrete areas of the authenticating layer. Beyond authentication, the conductive layer does not contain any useful information.
U.S. patent application Ser. No. 09/059,985 by Verschuur, Mitchell, Jr., and Leordeanu describes a capacitive method and apparatus for reading barcode printed on inserts and hidden inside sealed envelopes. Changes in a measurement of capacitive coupling between two electrodes in the presence of the barcode is interpreted to distinguish different barcode patterns. This application is hereby incorporated by reference.
A number of factors can affect such capacitive coupling measurements including wobble of the envelopes past the electrodes, vibration of the envelope transport, different numbers or thicknesses of dielectric layers separating the barcode from the electrodes, variations in the position or angular orientation of the barcode, and overcoupling effects between adjacent bars of the barcode.
SUMMARY OF INVENTION
Our invention includes among its embodiments a new reader that makes capacitive coupling measurements to acquire information encoded by differentially conductive patterns. Inserts within envelopes and other hidden substrates can be printed with a conductive or dielectric ink in the form of barcode or other symbols and advanced through our reader to convey information otherwise hidden to conventional optical readers. The coupling measurements can be made simultaneously and compared with each other independently of structural, environmental, or other factors that affect the measurements collectively to distinguish features within the patterns from one another.
For example, our reader for acquiring information encoded by a differentially conductive pattern can include a plurality of electrodes positioned within one or more electrical fields generated by at least one of the electrodes. A signal processor obtains capacitive coupling measurements of the differentially conductive pattern between at least three different pairings of the electrodes as the pattern is relatively moved through the one or more electrical fields. A logic processor compares the simultaneous measurements with each other independently of variations having similar effects on the compared measurements to distinguish features of the differentially conductive pattern.
Preferably, the logic processor compares simultaneous measurements from a first grouping of the paired electrodes and uses the outcome of this comparison to trigger another comparison between simultaneous measurements from a second grouping of the paired electrodes to distinguish the features of the pattern. The former comparison can also be used to locate reference points in the pattern as the pattern is advanced past the electrodes.
One embodiment, which is particularly useful for reading barcode, arranges the electrodes in an array and positions the electrodes along a common axis that is coincident with a d
Hrubes Franz
Verschuur Gerrit L.
Eugene Stephens & Associates
Lee Michael G
Micro-Epsilon Mess Technik
Ryan Thomas B.
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