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# Print Direction Determination for Optimal Throughput in Bidirectional Printers

IP.com Disclosure Number: IPCOM000034392D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 3 page(s) / 36K

IBM

## Related People

Hoang, CM: AUTHOR

## Abstract

Disclosed is a software method to determine the print direction which requires minimum time to finish a print cycle in bidirectional printer. As soon as the control software obtains the beginning position BP and the ending position EP of a print line, it must determine the print direction of this print line. Incorrect decision may cause some extra carrier movement, therefore, reducing the overall throughput of the printer. The method described below assists the control software to make a correct decision. First, the control software calculates the middle position MP of the print line using the following formula: MP = (EP - BP) / 2 Second, the control software obtains the present status of the carrier. At any one point, the carrier status is either idle, moving for a non-print move, or moving for a print move.

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Print Direction Determination for Optimal Throughput in Bidirectional Printers

Disclosed is a software method to determine the print direction which requires minimum time to finish a print cycle in bidirectional printer. As soon as the control software obtains the beginning position BP and the ending position EP of a print line, it must determine the print direction of this print line. Incorrect decision may cause some extra carrier movement, therefore, reducing the overall throughput of the printer. The method described below assists the control software to make a correct decision. First, the control software calculates the middle position MP of the print line using the following formula: MP = (EP - BP) / 2 Second, the control software obtains the present status of the carrier. At any one point, the carrier status is either idle, moving for a non-print move, or moving for a print move. The carrier is idle when the carrier motor is off. A non-print move is a move in which the printing process does not occur. A non-print move is used to position the carrier to a known position such as the paper-sense position. Therefore, the carrier must stop at the desired stop position DSP before another move can be performed. A print move is a move in which the printing process occurs. In a print move, the stop position SP is known but not important. The move can be extended to stop at different location as long as the printing process is finished. Last, the control software selects one of the three procedures described below, based on the carrier status, and follows that procedure to select the print direction. A. PROCEDURE #1: This procedure is used when the carrier is idle. In this procedure, the control software selects the left-to-right print direction when the carrier position CR is less than or equal to the middle position MP. Otherwise, it selects the right-to-left print direction. B. PROCEDURE #2: This procedure is used when the carrier is performed a non-print move. The control software uses the same above technique to determine the print direction. However, the desired stop position DSP is used instead of the carrier position CP. C. PROCEDURE #3: This procedure is used when the carrier is performing a print move. The control software uses the following steps to determine the print direction: 1. Subtract the acceleration distance AD associated

with the print speed PSP from the beginning

position BP. The result is called

acceleration-left-point ALP.

ending position EP. The result is called

acceleration-right-point ARP.

3. If the stop position SP is less than or equal to

the acceleration-left-point ALP, the print

direction will be from left to right. The control

software should extend the print move to stop at

1

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the acceleration-left-point ALP if a...