System for reading bar code symbols using portable bar code symbol readers having one-way RF signal transmission links with base stations

Abstract

A code symbol reading device includes a portable housing that contains a light source. Light from the light source is projected into a scan field external to the housing and onto a code symbol on an object located within the scan field. The light reflected off the code symbol is detected within the housing to produce scan data that is indicative of the detected light intensity. The scan data is processed to detect and decode the code symbol and to produce symbol character data that are representative of the decoded code symbol. A data packet utilizing the symbol character data is synthesized and modulated onto a carrier signal that is transmitted to a base unit where the carrier signal is demodulated and the data packet recovered. The received data packet is analyzed to recover the symbol character data, and an acknowledgment signal is produced to acknowledge the receipt of the symbol character data at the base unit.

Description

[0001] This is a Continuation of patent application Ser. No. 09 / 346,859, filed on Jul. 2, 1999, which is a Continuation-In-Part of patent application Ser. No. 07 / 761,123 filed on Sep. 17, 1991, and now issued as U.S. Pat. No. 5,340,971.[0002] 1. Field of the Invention[0003] The present invention relates to bar code symbol reading systems having one or more base stations or units, and one or more hand-held bar code symbol reading devices each remotely suitable from the base station(s) and capable of sending symbol character data over distance(s) thereto.[0004] 2. Brief Description of the Prior Art[0005] Bar code symbols have become widely used in many commercial environments such as, for example, point-of-sale (POS) stations in retail stores and supermarkets, inventory and document tracking, and diverse data control applications. To meet the growing demands of this recent technological innovation, bar code symbol readers of various types have been developed for scanning and decoding ...

AI Technical Summary

Benefits of technology

[0018] It is another object of the present invention to provide such an automatic bar code symbol reading system with a mode of operation that permits the user to automatically read one or more bar code symbols on an object in a consecutive manner.

[0021] A further object of the present invention is to provide such an automatic bar code symbol reading system, in which a novel data packet transmission and reception scheme is used to minimize the occurrence of data packet interference at each base unit during data packet reception.

[0023] A further object is to provide such an automatic bar code symbol reading device, in which the automatic hand-supportable bar code (symbol) reading device has an infrared (IR) based object detection field which spatially encompasses at least a portion of its visible laser light scan field along the operative scanning range of the device, thereby improving the laser beam pointing efficiency of the device during the automatic bar code reading process of the present invention.

[0029] An even further object of the present invention is to provide an automatic hand-supportable bar code reading device which prevents multiple reading of the same bar code symbol due to dwelling of the laser scanning beam upon a bar code symbol for an extended period of time.

[0032] It is yet a further object of the present invention to provide a portable, fully automatic bar code symbol reading system which is compact, simple to use and versatile.

[0034] A further object of the present invention is to provide a wireless automatic bar code symbol reading device having a housing that can be comfortably mounted to the wrist of its user, similar to a wrist bracelet or a watch, and which can be reconfigured when not in use to provide its user greater hand mobility.

Problems solved by technology

A major drawback with bar code symbol reading systems using the physical-wiring method of interconnection is that the movement of the portable hand-held laser scanning device is restricted by the overall (extended) length of the flexible cord used.

In many applications, such as product inventory, the use of such bar code symbol reading systems is simply unacceptable.

While prior art bar code symbol reading systems employing the wireless method of interconnection offer a marked degree of flexibility over systems utilizing the physical wiring method of interconnection, such prior art systems nevertheless suffer from a number of shortcomings and drawbacks.

In particular, these prior art systems require two-way packet communications which involves the use of complex data communications protocols and a separate transmitter and a receiver (i.e., transceiver) at each hand-held bar code symbol reader and base unit in the system.

Typically, these data communications requirements increase the cost of manufacture of such systems, and substantially increase the electrical power consumption at each hand-held bar code symbol reader.

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