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Print Head Speed and Stopping Distance Specification for Voltage-Driven Motor Control Systems

IP.com Disclosure Number: IPCOM000062415D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 4 page(s) / 52K

Publishing Venue

IBM

Related People

Cavill, BR: AUTHOR [+2]

Abstract

A technique is described whereby the operational speed of a matrix print head is optimized at specified dot densities, based on the distance traveled by the print head. Also, the stopping distance overtravel is minimized while providing precise print positioning of the head. The concept described herein selects the optimum motor speed to print a line, based on the length of the line to be printed. A maximum motor speed, based on the distance of head movement, is selected to advance the head rapidly during non-printing operations. A microprocessor circuit is used to calculate the stopping distance from various speeds. During printing, the stopping distance is calculated and controlled, so as to optimize printing throughput.

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Print Head Speed and Stopping Distance Specification for Voltage-Driven Motor Control Systems

A technique is described whereby the operational speed of a matrix print head is optimized at specified dot densities, based on the distance traveled by the print head. Also, the stopping distance overtravel is minimized while providing precise print positioning of the head. The concept described herein selects the optimum motor speed to print a line, based on the length of the line to be printed. A maximum motor speed, based on the distance of head movement, is selected to advance the head rapidly during non-printing operations. A microprocessor circuit is used to calculate the stopping distance from various speeds. During printing, the stopping distance is calculated and controlled, so as to optimize printing throughput. This is done by allowing the head drive motor to stop before printing is completed, providing a minimum of overtravel to occur beyond the stop print target. When required, a time delay is automatically calculated and performed so as to prevent printing while forms are advancing. The nominal head speed is selected based on the maximum actuator repetition rate at a specified pel (picture element). This speed is specified by a binary value equivalent to six times the desired motor velocity (in inches/second). This speed is the final steady-state speed which will allow the actuators to print at the required density and at the maximum duty cycle, or at a restricted duty cycle if heavy dot patterns are required from the print head. The spacing at which dots are placed on the paper (pel) is not dependent on the linear speed of the head, since a fire time correction algorithm measures the velocity and then compensates for differences in linear velocity. If the distance from the start print to the stop print targets is small, the desired steady state velocity will be reduced from the nominal maximum value since printing begins and ends before a final speed would be reached. The microprocessor determines the distance to be travelled so as to determine if a final high speed velocity drive force is required. This is based on the distance from the present location to the future print location as well as the printing distance requirement. The microprocessor first calculates the stopping distance by means of the equation: Stopping Distance = (Speed Value) / 144 and then calculates 2.5 times the value. This result is compared to the nominal maximum speed, and if 2.5 times the stopping distance is less than the total distance to be traveled, then the nominal maximum speed is used. If the 2.5 times the stopping distance is not less than the total movement distance, then the nominal maximum speed is halved and a new stopping distance is calculated. Using this new speed, 2.5 times the stopping distance is calculated and compared with the total movement distance. If the 2.5 times the stopping distance (of the reduced speed) is less than the...