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Browse Prior Art Database

Robust Barcode Decoding Method in an Automated Tape Library

IP.com Disclosure Number: IPCOM000105189D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 128K

Publishing Venue

IBM

Related People

Kishi, G: AUTHOR

Abstract

The IBM 3495 Tape Library Dataserver (an automated tape library) uses a multiple axis robot mounted on a sled to handle cartridges. Grippers are mounted on the end of the robot arm to pick cartridges. At least one camera is mounted adjacent to the grippers at the end of the robot arm.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 43% of the total text.

Robust Barcode Decoding Method in an Automated Tape Library

      The IBM 3495 Tape Library Dataserver (an automated tape
library) uses a multiple axis robot mounted on a sled to handle
cartridges.  Grippers are mounted on the end of the robot arm to pick
cartridges.  At least one camera is mounted adjacent to the grippers
at the end of the robot arm.

      IBM 3480 Cartridge System Tapes and IBM Enhanced Capacity
Cartridge System Tapes are stored in racks, and the accessor moves
tapes between the racks and IBM 3490 tape drives attached to the
library.

      The camera is attached to a vision system which digitizes the
camera image, and is programmed to analyze the digitized images.  The
camera is used to read the barcode labels on the tape cartridges.

      In our library, cartridges can be intermixed with two different
vendors supplying labels.  Each label consists of standard 3 of 9
barcode characters, but uses a different coding scheme.  A fast and
robust method to read barcodes using a camera based vision system is
described which quickly determines which type of label it is reading,
reads the label, and verifies it.

      Multiple adjacent stripes are analyzed in a pattern to provide
many read attempts in a single camera frame.  The first attempt is
centered to analyze the most likely pass first.  Each stripe can be
read in either both directions, or with either of two different
coding schemes.  A method is described which provides the ability to
read the barcode correctly even if the start character is misread.

      The camera image contains the image of the barcode label.  The
barcode is written along a vertical stripe in the label as shown in
the figure.

      Since the barcode is multiple pixels wide, the vision system
can analyze many "stripes" down the barcode, each stripe being one
pixel wide.

      When reading the barcode, first the barcode center and
orientation are determined.  The center vertical stripe (indicated by
'1') is analyzed first.  If required, other stripes are analyzed, the
sequence being 1,2,3,...

      In the system, stripes are read until 2 stripes meet the
following conditions:

o   Start, end and label characters found.
o   Two stripes read with the same label characters.
o   Each stripe is analyzed to determine which Vendor label is being
    used.

      Vendor A uses a standard 3 of 9 barcode scheme which must be
read from bottom to top.  The label consists of 8 characters.  The
first character is an asterisk, the standard 3 of 9 start character.
The next six characters are the actual cartridge identifying
characters.  The last character is an asterisk, the standard 3 of 9
stop character.

      Vendor B uses a non-standard 3 of 9 barcode scheme which must
be read from top to bottom.  The label consists of 8 characters.  The
first character is a non-standard start character.  The next six
characters are the actual cartridge ide...