System and method for preventing authorized movement of cordless bar code symbol readers from designated scanning environments

• US 5,929,419 A
• Filed: 07/09/1997
• Issued: 07/27/1999
• Est. Priority Date: 09/17/1990
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Colavito, Stephen J., Rockstein, George B., Knowles, Carl Harry, Wilz, David M., German, Gene
• Primary Examiner(s): Le, Thien Minh
• Application Number:
  US08/890,085
• Time in Patent Office: 748 Days
• Field of Search: 235/492, 235/493, 235/449, 235/379, 235/375, 340/566, 340/571, 340/825.32
• US Class Current: 235/462.27
• CPC Class Codes: G02B 26/106 having diffraction gratings as scanning elements, e.g. holographic scanners holographic optical elements G02B5/32, holography G03H
• CPC Class Codes: G06K 17/0022 arrangements or provisious for transferring data to distant stations, e.g. from a sensing device "transfer between computer elements G06F13/00 "; data-transmission H04L
• CPC Class Codes: G06K 2007/10534 Scanner to be worn on a finger or on a wrist
• CPC Class Codes: G06K 2207/1012 Special detection of object
• CPC Class Codes: G06K 2207/1016 Motor control or optical moving unit control
• CPC Class Codes: G06K 2207/1017 Programmable
• CPC Class Codes: G06K 2207/1018 Source control
• CPC Class Codes: G06K 7/10 by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
• CPC Class Codes: G06K 7/10564 Light sources
• CPC Class Codes: G06K 7/10584 Source control
• CPC Class Codes: G06K 7/10594 Beam path
• CPC Class Codes: G06K 7/10603 Basic scanning using moving elements
• CPC Class Codes: G06K 7/10663 using hologram
• CPC Class Codes: G06K 7/10673 Parallel lines
• CPC Class Codes: G06K 7/10693 for omnidirectional scanning
• CPC Class Codes: G06K 7/10702 Particularities of propagating elements, e.g. lenses, mirrors G06K7/10831 takes precedence
• CPC Class Codes: G06K 7/10792 Special measures in relation to the object to be scanned
• CPC Class Codes: G06K 7/10801 Multidistance reading
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03
• CPC Class Codes: G06K 7/10861 : sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48
• CPC Class Codes: G06K 7/10871 : randomly oriented data-fields, code-marks therefore, e.g. concentric circles-code
• CPC Class Codes: G06K 7/10881 : constructional details of hand-held scanners
• CPC Class Codes: G06K 7/10891 : the scanner to be worn on a finger or on a wrist
• CPC Class Codes: G06K 7/109 : adaptations to make the hand-held scanner useable as a fixed scanner
• CPC Class Codes: G06K 7/14 : using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/1443 : locating of the code in an image

Abstract

Disclosed is a fully automatic bar code reading system having at least one automatic (i.e., triggerless) portable bar code symbol reading device, and an associated base unit positioned within the data transmission range thereof without a physical wiring connection thereto. After each successful reading of a bar code symbol, the bar code symbol reading device automatically produces symbol character data representative of the decoded bar code symbol, synthesizes a group of data packets each containing the symbol character data, and then transmits the synthesized group of data packets to the base unit. Upon the successful receipt of one of the transmitted data packets and the recovery of symbol character data therefrom, the base unit generates an acoustical acknowledgement signal that is perceptible to the user of the bar code symbol reading device and indicates the transmitted symbol character data has been successfully received. In typical applications, a plurality of such bar code systems are used in physical proximity with each other, such as in conventional retail point-of-purchase (POS) environments. In accordance with the present invention, radio frequency (RF) carrier signals of the same frequency are used by each hand-supportable bar code symbol reading device to transmit groups of data packets to respective base units. Data packet interference at each base unit is minimized during data packet reception by using a novel data packet transmission scheme. In accordance therewith, each bar code symbol reading device transmits the data packets in each of its data packet groups with a unique time delay imposed therebetween, thus creating data packet transmission "slots" or "windows" on the time domain, during which other groups of data packets may be transmitted from neighboring bar code symbol reading devices and received at their respective base units.

Claims

1. A bar code symbol reading system comprising:

a portable bar code symbol reading device including a hand-supportable housing, and means for reading a bar code symbol on an object and producing symbol character data representative of said read bar code symbol; and

an electrically-passive target affixed to said hand-supportable housing and being operably interactive with an invisible interrogation electromagnetic field created at a point of interrogation within a working environment within which said bar code symbol reading system is installed, thereby to indicate the presence of said hand-supportable housing within said interrogation field.

2. The bar code symbol reading system of claim 1, which further comprises

means for creating a magnetic-based interrogation field at said point of interrogation using electrical energy, so that said magnetic-based interrogation field interacts with said target as said bar code symbol reading device is moved through said magnetic-based interrogation field;

means for detecting a perturbation in said electrical energy, as said magnetic-based interrogation field interacts with said target; and

means for producing an alarm signal in response to the detection of said perturbation.

3. The bar code symbol reading system of claim 1, which further comprises

a base unit remotely positionable from said portable bar code symbol reading device, and including means for receiving a modulated carrier signal, and

wherein said bar code symbol reading device further comprises

means for transmitting an electromagnetic carrier signal to said base unit, and

means for modulating said carrier signal using said symbol carrier data.