Method and apparatus for detecting print-termination in line printer

In a line printer comprising:

• a character carrier adapted to continuously move along a print line;
• a plurality of print hammers arranged side by side along the print line so as to be in opposition to said character carrier;
• a code generator for storing character codes according to the arrangement of characters carried on said character carrier;
• a print line buffer for storing print data;
• a print line buffer flag and a pre-scanning flag for storing information indicating presence/absence of print data for every print hammer column when the print data is stored in said print line buffer;
• and a comparing means for comparing a character code supplied from said code generator with a print datum supplied from said print line buffer so as to generate a print hammer drive signal and a signal to rewrite a corresponding column of said print line buffer flag to indicate "absence of print data" when the character code and the print datum accord with each other;
• a method of detecting termination of printing in said line printer comprising the steps of:
• performing anticipatory comparison to judge whether a character X columns after a character currently opposing one of said print hammer columns accords with the print datum or not;
• rewriting contents of a corresponding column of said pre-scanning flag to indicate "absence of print data" when the step of anticipatory comparison proves that the character X columns after said character currently opposing said one print hammer column accords with the print datum;
• and
• recognizing termination of printing when all the columns of said pre-scanning flag indicate "absence of print data".

In a line printer comprising:

• a character carrier adapted to continuously move along a print line;
• a plurality of print hammers arranged side by side along the print line so as to be in opposition to said character carrier;
• a code generator for storing character codes according to the arrangement of characters carried on said character carrier;
• a print line buffer for storing print data;
• and a comparing means for comparing a character code supplied from said code generator with a print datum supplied from said print line buffer and for generating a print hammer drive signal when the character code and the print data accord with each other;
• a print-termination detecting apparatus in said line printer, comprising:
• a pre-scanning flag for storing information indicating presence/absence of print data for every print hammer column;
• a predicting code generator for storing a code of a character X columns after a current character on said character carrier in an address corresponding to that of said code generator;
• an anticipatory comparing means for performing anticipatory comparison between a character code supplied from said predicting code generator and a print datum supplied from said print line buffer and for generating a signal to rewrite the contents of a corresponding column of said pre-scanning flag to indicate "absence of print data" when the character code and the print data accord with each other;
• and
• a pre-scanning termination detector for detecting a print-termination signal when all the columns of said pre-scanning flag indicate "absence of print data".

In a line printer comprising:

• a character carrier adapted to continuously move along a print line;
• a plurality of print hammers arranged side by side along the print line so as to be in opposition to said character carrier;
• a code generator for storing character codes according to the arrangement of characters carried on said character carrier;
• a print line buffer for storing print data;
• a print line buffer flag for storing information indicating presence/absence of print data for every print hammer column when the print data is stored in said print line buffer;
• and a comparing emans for comparing a character code supplied from said code generator with a print datum supplied from said print line buffer and for generating a print hammer drive signal and a signal to rewrite the contents of a corresponding column of said pre-scanning flag to indicate "absence of print data" when the character code and the print data accord with each other;
• a print-termination detecting apparatus in said line printer, comprising:
• a pre-scanning flag for storing information indicating presence/absence of print data for every print hammer column;
• a predicting code generator for storing a code of a character X columns after a current character on said character carrier in an address corresponding to that of said code generator;
• an anticipatory comparing means for performing anticipatory comparison between a character code supplied from said predicting code generator and a print datum supplied from said print line buffer and for generating a signal to rewrite the contents of a corresponding column of said pre-scanning flag to indicate "absence of print data" when the character code and the print datum accord with each other;
• and
• a pre-scanning termination detector for detecting a print-termination signal when all the columns of said pre-scanning flag indicate "absence of print data".

In a line printer comprising:

• a character carrier continuously moving along a print line;
• a plurality of print hammers arranged side by side along the print line so as to be in opposition to said character carrier;
• a code generator for storing character codes in accordance with the arrangement of characters on said character carrier;
• a print line buffer for storing print data;
• a print line buffer flag for storing information indicating presence/absence of print data in the respective print hammer columns when print data are stored in said print line buffer;
• a comparing means for comparing a character code supplied from said code generator with a print datum supplied from said print line buffer and for generating a print hammer drive signal when the character code and the print datum accord with each other;
• and a code address counter for generating address data for making access to said code generator;
• a print-termination detecting apparatus comprising:
• a pre-scanning flag for storing information indicating presence/absence of print data corresponding to the respective print hammer columns;
• an adder provided between said code address counter and said code generator so as to operate based on a time-division signal generated in a predetermined period in a printing cycle in a manner so that said adder outputs an address datum of said code address counter as it is or outputs a value obtained by adding a predetermined number X to an address datum provided by said code address counter;
• an anticipatory comparing means for performing anticipatory comparison to judge whether a character code generated from said code generator at the time when said adder has performed the addition of said predetermined number X accords with a print datum supplied from said print line buffer or not and for generating a signal to rewrite the contents of a corresponding column of said pre-scanning flag when the character code and the print datum accord with each other;
• and
• a pre-scanning termination detector for generating a print-termination signal when all the columns of said pre-scanning flag indicate "absence of print data".

In a line printer comprising:

• a character carrier continuously moving along a print line;
• a plurality of print hammers arranged side by side along the print line so as to be in opposition to said character carrier;
• a code generator for storing character codes in accordance with the arrangement of characters on said character carrier;
• a print line buffer for storing print data;
• a print line buffer flag for storing information indicating presence/absence of print data in the respective print hammer columns when print data are stored in said print line buffer;
• a comparing means for comparing a character code supplied from said code generator with a print datum supplied from said print line buffer and for generating a print hammer drive signal when the character code and the print datum accord with each other;
• and a code address counter for generating address data for making access to said code generator;
• a print-termination detecting apparatus comprising:
• an adder provided between said code address counter and said code generator so as to operate based on a time-division signal generated in a predetermined period in a printing cycle in a manner so that said adder outputs an address datum of said code address counter as it is or outputs a value obtained by adding a predetermined number X to an address datum provided by said code address counter;
• a pre-scanning flag for storing information indicating presence/absence of print data corresponding to the respective print hammer columns, said pre-scanning flag being arranged so that the contents of a corresponding column of said pre-scanning flag are rewritten to indicate "absence of print data" based on a signal generated from said comparing means for performing anticipatory comparison to judge whether a character code supplied from said code generator accords with a print datum supplied from said print line buffer at the time when said adder has performed the addition of said predetermined number;
• and
• a pre-scanning termination detector for generating an print-termination signal when all the columns of said pre-scanning flag indicate "absence of print data".