Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1999-12-14
2001-02-20
Pitts, Harold I. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S462120
Reexamination Certificate
active
06189792
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to improvements in systems for reading bar codes, and particularly to advantageous aspects of a system and methods for the detection and correction of errors in the reading of bar codes.
2. Description of the Prior Art
Bar coding systems, such as the Uniform Product Code (UPC) system, are commonly used to identify items, such as products for sale in a retail store. In such systems, bar codes consisting of a series of bars and spaces of varying widths are printed onto labels that are affixed to the products for sale, or are printed directly onto the product packaging. Scanners at the checkout terminal are then used to read the bar codes. This approach allows more information to be entered in less time, as scanning requires significantly less time than manually entering pricing and product identification information. Further, the use of bar codes eliminates errors arising from keyboarding errors by checkout personnel.
Unfortunately, bar-coded labels are not always printed perfectly. Imperfections caused by the printing process frequently render the printed bar code unreadable to the bar code scanning equipment. Such cases require human intervention. Typically, the method of human intervention is to enter the bar code data manually into a keyboard, terminal, or other input device. The prevalence of this problem is one reason that the data on most bar-coded labels are printed in human-readable form adjacent to the bars and spaces comprising the bar code itself.
Each human intervention produces a delay in the scanning process. There is thus a need for a scanning system that minimizes the number of human interventions required.
SUMMARY OF THE INVENTION
One aspect of the invention provides a system for correcting improperly printed or otherwise defective bar codes. The system scans a bar code and determines whether the scanned bar code data is correct. If the scanned bar code data is incorrect, the system uses the incorrect scanned bar code data to create a scan-based printhead model. Manually entered data is then used to construct an active printhead model. The scan-based printhead model and the active printhead model are then compared in order to identify printhead defects, which are stored to correct future bar code scans.
Additional features and advantages of the present invention will become apparent by reference to the following detailed description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic representation of a scanning system in accordance with an exemplary embodiment of the present invention.
FIG. 1A
is a schematic representation of a scanning system in accordance with a further exemplary embodiment of the present invention.
FIG. 2
is an enlarged left-margin portion of an exemplary bar code label and a linear printhead used to print the bar code label.
FIG. 3
illustrates a defective printhead element causing an error in the bar code.
FIG. 4
illustrates another example of a defective printhead element causing a different error in the bar code.
FIG. 5
is a flowchart of an exemplary embodiment of a printhead defect identification method in accordance with an aspect of the present invention.
FIG. 6
is a flowchart of an exemplary embodiment of a printhead model construction method in accordance with the present invention.
FIG. 7
is an enlarged left-margin portion of a scanned bar code information and a printhead model constructed from the scanned bar code information in accordance with the method illustrated in the
FIG. 6
flowchart.
FIG. 8
is a flowchart of an exemplary embodiment of a method for constructing an active printhead model in accordance with the present invention.
FIG. 9
is an enlarged left-margin portion of a bar code constructed based upon keypad-entered data and the active printhead model constructed from the data in accordance with the method illustrated in the
FIG. 8
flowchart.
FIG. 10
is a diagram showing the identification of printhead defects based upon a comparison of the models constructed in
FIGS. 6 through 9
.
FIG. 11
is a flowchart of an exemplary embodiment of a method according to the present invention for correcting future scans based upon stored printhead defect information.
REFERENCES:
patent: 5262625 (1993-11-01), Tom et al.
patent: 5276316 (1994-01-01), Blanford
patent: 5602382 (1997-02-01), Ulvr et al.
patent: 5767498 (1998-06-01), Heske, III et al.
NCR Corporation
Pitts Harold I.
Priest Peter H.
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