System for enabling decoding of bar code and other symbols with a digital microcomputer connected via the input/output port thereof to the scanner

Abstract

A scanner communicates with a microcomputer over a serial communications link utilizing the serial I/O port of the microcomputer. Both signals representing the data which is scanned and signals representing commands to the scanner and commands from the scanner indicative of the status thereof (e.g., scanner trigger actuation) are communicated over a plurality of lines in the communication link. These lines may be of the type utilized for transmission of data and commands in accordance with a communications protocol, such as the RS-232 protocol. Interrupts are generated when the scanner is connected to the serial port via the communication link and the microcomputer is available for decoding. Then appropriate interrupts are generated to actuate the scanner and to respond to the data. The scanner may be a laser or optical beam scanner or a wand which is moved across a bar code symbol. The symbol has bars which are relatively opaque and reflective (black or white). The microcomputer translates the data which represents the width of each bar and the number of bars and the detection of the end of a bar code symbol (Quiet Zone) into digital values which are stored in memory and presented for decoding in accordance with programming of the microcomputer which decodes the symbol. The decoded symbol may be displayed graphically, with its opaque and reflective bars and the alphanumerics which the symbol represents, on the screen of a terminal including the microcomputer.

We claim:  
     
       1. A computer system operable as a platform for symbol reading scanners so that the computer controls a scanner and processes data from the scanner representing symbols read by the scanner for decoding the symbols into information corresponding thereto, said system comprising: 
       a general purpose computer separate from the scanner and having a communications port connectable to the scanner for receiving undecoded data representing the symbols via a communications link between the scanner and the port;  
       means in said computer responsive to said communications over said link indicating that the scanner is in data communicating relationship with said computer over said link and that said computer is ready to decode the data;  
       means in said computer for transmitting and receiving commands necessary for controlling the scanner;  
       means for translating said data into a format for decoding; and  
       means connected in said link for preventing unauthorized transfer of data into and out of said computer.  
     
     
       2. The system according to  claim 1  wherein: 
       said link has a plurality of lines;  
       said computer has means for transmitting signals over a first of said lines and for receiving signals from the scanner over a second of said lines; and  
       said means for preventing unauthorized transfer includes means responsive to a predetermined sequence of signals transmitted over said first line for providing an output on said second line to authorize said computer to transfer data.  
     
     
       3. The system according to  claim 2  wherein said signals carried over said first line represent requests from said computer to send signals, and said computer receives signals representing readiness to receive data over said second line. 
     
     
       4. A method for reading data with the assistance of a general purpose computer, comprising the steps of: 
       
         detecting light incident on a photodetector of a peripheral reading device, and generating an electrical signal thereby;  
       
       
         generating, from said electrical signal, digital data comprising pulse width information corresponding to widths of light features and dark features of a target imaged by said photodetector;  
       
       
         transferring said digital data via a bidirectional communication port to a general purpose computer;  
       
       
         timing the widths of said pulses, and generating a plurality of width measurement values thereby; and  
       
       
         decoding a symbol according to said width measurement values using a processor of said general purpose computer. 
       
     
     
       5. The method of  claim 4 , wherein the step of detecting an amount of light incident on a photodetector comprises the step of detecting light incident on a charge- coupled device.   
     
     
       6. The method of  claim 4 , wherein said step of timing the widths of said pulses, and generating a plurality of width measurement values thereby, comprises the step of resetting a stopwatch timer at points in time corresponding to high and low state transitions in said electrical signal, and recording pulse width time values from the stopwatch timer immediately before the stopwatch timer is reset. 
     
     
       7. The method of  claim 4 , further comprising the step of counting a number of features in said symbol using said general purpose computer. 
     
     
       8. The method of  claim 4 , further comprising the step of transmitting a signal from said general purpose computer via said bidirectional communication port to said peripheral reading device indicating that a symbol has been properly decoded. 
     
     
       9. The method of  claim 4 , wherein said peripheral reading device comprises either an optical beam scanner or a wand, and wherein said method further comprises, for said optical beam scanner, the step of sweeping an optical beam across said symbol, and for said wand, the step of moving said wand across said symbol. 
     
     
       10. The method of  claim 4 , further comprising the step of transmitting a unique series of binary digits from said peripheral reading device to said bidirectional communication port prior to transmitting said digital data to said general purpose computer. 
     
     
       11. The method of  claim 4 , wherein said step of transferring said digital data via a bidirectional communication port to a general purpose computer comprises the step of transferring said digital data via a serial communication port to the general purpose computer. 
     
     
       12. The method of  claim 11 , wherein said communication path comprises a serial communication path. 
     
     
       13. A method of interfacing a peripheral reading device and a general purpose computer, comprising the steps of: 
       
         detecting light incident on a photodetector of a peripheral reading device, and generating an electrical signal in response thereto;  
       
       
         generating, from said electrical signal, a binary signal comprising pulse width information indicating widths of relatively light regions and relatively dark regions of a target imaged by said photodetector;  
       
       
         transmitting, via a communication path, a code sequence from said peripheral reading device to a general purpose computer;  
       
       
         transmitting, via said communication path, said binary signal from said peripheral reading device to said general purpose computer; and  
       
       
         processing said binary signal at said general purpose computer only if said code sequence matches a predetermined code sequence. 
       
     
     
       14. A system for reading data, comprising: 
       
         a photodetector, said photodetector outputting an electrical signal;  
       
       
         a digitizer connected to said photodetector, said digitizer outputting a binary signal having transitions between high and low states at points in time corresponding to transitions between lighter and darker regions of a symbol imaged by said photodetector;  
       
       
         a timer for measuring feature widths of said binary signal, said timer generating a series of pulse width values indicating widths of features of said binary signal; and  
       
       
         a general purpose computer, said general purpose computer comprising a bidirectional serial port, a processor and a memory, said processor responsive to programmed instructions for decoding a symbol according to the measured feature widths of said binary signal, and said processor outputting data over said bidirectional serial port. 
       
     
     
       15. The system for reading data of  claim 14 , wherein said photodetector comprises a charge- coupled device  ( CCD ) .   
     
     
       16. The system for reading data of  claim 14 , further comprising a counter responsive to said binary signal for storing a total number of features of said symbol being imaged. 
     
     
       17. The system for reading data of  claim 14 , further comprising a good read signal output from said general purpose computer via said serial port to a peripheral reader comprising said photodetector, said good read signal indicating that a symbol has been successfully decoded. 
     
     
       18. The system for reading data of  claim 14 , further comprising either a flying spot optical beam or a manually held wand for illuminating the symbol. 
     
     
       19. The system for reading data of  claim 14 , wherein said photodetector is part of a peripheral reading device, said peripheral reading device comprising a code generator outputting a predetermined code to the serial port of said general purpose computer prior to said general purpose computer receiving said measured feature widths.