Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
2001-09-17
2004-07-13
Lee, Diane I. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
Reexamination Certificate
active
06761314
ABSTRACT:
COPYRIGHT NOTIFICATION
A portion of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by any one of the patent disclosure, as it appears the Patent and Trademark Office, patent files or records, but otherwise reserves all copyright whatsoever.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to bar code reading and in particular to a new symbol with structure and features that make it particularly suitable for consumer-scanning applications. Its features include a compact start pattern that can be found without compute-intensive ratio checks, and an overall structure that supports variable-length messages while providing strong protection against short reads.
2. Background of the Invention
Bar code symbols are formed from bars or elements typically rectangular in shape with a variety of possible widths. The specific arrangement of elements defines the character represented according to a set of rules and definitions specified by the code or “symbology” used. The relative size of the bars and spaces is determined by the type of coding used as is the actual size of the bars and spaces. The number of characters (represented by the bar code symbol) is referred to as the density of the symbol. To encode the desired sequence of the characters, a collection of element arrangements are concatenated together to form the complete bar code symbol, with each character of the message being represented by its own corresponding group of elements. In some symbologies, a unique “start” and “stop” character is used to indicate when the bar code begins and ends. A number of different bar code symbologies are in widespread use including UPC/EAN, Code 39, Code 128, Codeabar, and Interleaved 2 of 5.
In order to increase the amount of data that can be represented or stored on a given amount of surface area, several more compact bar code symbologies have been developed. One of these code standards, Code 49, exemplifies a “two dimensional” symbol by reducing the vertical height of a one-dimensional symbol, and then stacking distinct rows of such one dimensional symbols, so that information is encoded both vertically as well as horizontally. That is, in Code 49, there are several rows of bar and space patterns, instead of only one row as in a “one dimensional” symbol. The structure of Code 49 is described in U.S. Pat. No. 4,794,239. Another two-dimensional symbology, known as “PDF417”, is described in U.S. Pat. No. 5,304,786.
Still other symbologies have been developed in which the symbol is comprised not of stacked rows, but a matrix array made up of hexagonal, square, polygonal and/or other geometric shapes, lines, or dots. Such symbols are described in, for example, U.S. Pat. Nos. 5,2276,315 and 4,794,239. Such matrix code symbologies may include Vericode, Datacode, and MAXICODE.
Ever since the advent of the Universal Product Code in the 1970's, linear bar code symbols have been widely adopted as an inexpensive but effective way of automating the link between printed numbers on paper and computer databases. Each “symbology” has its own advantages for certain applications. Because bar codes are so common in our daily environment, and used in so many different applications, it is often important that a symbology, or a distinct variant of a symbology, be dedicated to one specific application. For example, a bar code scanning system may read a barcode encoding a string of digits such as “12345678905”. It is very important that the system can unequivocally determine that this string is to be used to look up the price of a grocery item, and that the price can be found, using the decoded string of digits as a key, in a database of numbers assigned by the Uniform Code Council for this purpose. In the past many other symbologies and symbology variants have also been reserved for such specific uses, such as a Code 128 symbol for marking medical instruments, a 14-digit Interleaved Two-of-Five symbol for marking cases for logistics tracking, and a 6-digit Code 39 symbol for marking Telecommunications equipment.
One aspect held in common by all of the above traditional barcode applications, is that a worker (such as a checkout clerk at a supermarket) will be trained and paid to scan the specific kind of barcode required by the application. Recently, however, as the cost of computers, and of scanning hardware, has decreased, a new set of consumer-scanning applications have become feasible.
Consumer-scanning applications will in principle have many requirements in common with traditional bar code applications, except that the consumer-scanning application will increase the difficulty of meeting some of these requirements. In addition, consumer scanning places at least one new requirement on the symbology. The following paragraphs discuss the new requirements, and then the other requirements that differ in degree.
By definition, the consumer scanning system will be used by untrained and unpaid operators. An unpaid operator will simple abandon consumer scanning if it is perceived as difficult or unreliable. An untrained operator will put the scanning system at a disadvantage through poor technique (such as scanning at an angle, or scanning too close to completely cover the bar code). Thus, the ideal consumer-scanning symbology will facilitate easy intuitive scanning, and will survive an untrained operator's mistakes without these turning into decode errors (such as short reads) that could get into the system.
Traditional linear bar code symbologies are “framed” by relatively large areas, to the left and to the right of the bar code, that must be kept clear of all printing. These areas, called “Quiet Zones”, provide technical benefits that make designing and scanning such symbologies easier. However, these Quiet Zones require additional space to be reserved for the barcode. Moreover, they prevent graphics or text from being tightly coupled to the barcode. This is a problem in the consumer scanning environment, where graphical and textual clues, placed immediately adjacent to the bar code, can help untrained consumer operators find the bar code within graphics, and help them understand what the result of scanning a given consumer barcode will be. Thus, the ideal consumer scanning symbology will allow text and graphics to be tightly coupled to the bar code, not kept distant from it.
Many traditional bar code applications need to fit the printed symbols in a relatively small area. Consumer scanning applications increase the importance of this requirement, as the bar codes will need to fit in constrained spaces such as to mark line items in catalogue tables, and to fit within a single line of text in a newspaper article. Thus, the ideal consumer scanning symbology needs to minimize both the height and the length of the printed bar code.
Many traditional bar code applications are cost-sensitive. However, consumer-scanning applications are extremely cost-sensitive. Thus, the ideal consumer scanning symbology can be scanned by a broad range of low-cost scanning technologies, and will be decodable by a low-cost, low-capability microprocessor system.
Most traditional bar code applications suffer from some variation in print quality, often resulting from attempts to save operating costs of label stock and regular printer maintenance. However, extremely poor print quality is usually avoided in business scanning situations, because of the need to maintain a good business relationship between the organization that prints the barcodes, and the organization that must scan them. Consumer-scanning applications are more likely to experience severe print quality problems for two reasons. First, the checks and balances between a supplier and a receiver in a business relationship will not be present in a consumer-scanning application. Second, consumer barcodes will be printed, not on labels, but on newspapers, in yellow pages, and on other forms of paper that are not amenable to high-accuracy printing. T
Kirschstein et al.
Lee Diane I.
Symbol Technologies Inc.
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