Browse Prior Art Database

Power-Averaging Technique for Dot-Band Printers

IP.com Disclosure Number: IPCOM000037118D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Johnson, WM: AUTHOR

Abstract

Disclosed is an energy management technique for dot-band printers that allows for efficient utilization of the power supply and provides a low cost method for implementing a print density control function.

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Power-Averaging Technique for Dot-Band Printers

Disclosed is an energy management technique for dot-band printers that allows for efficient utilization of the power supply and provides a low cost method for implementing a print density control function.

Power supplies for line printers that print successive "dot rows" must deliver very high transient load currents over short time intervals. However, the average current required from the supply is much less than the peak current. This frequently results in inefficient use of the power supply since most of the internal energy storage components (inductors and capacitors) must be sized for the peak current instead of the average current.

The top, middle, and bottom dot rows of normal alpha-numerical text have a much higher dot density than the intermediate dot rows. Thus, the current required from the power supply is much higher for these dot rows. A power supply that is current limited to the average load required over all dot rows will run in a current limit mode during high density dot rows, allowing components internal to the power supply to be sized only for the average load instead of the peak. Output capacitors deliver the residual current to the load during these time intervals. Since high density dot rows are always followed by low density dot rows during normal alpha-numerical text printing, the capacitors only supply the residual load current for a short time interval.

Typical waveforms demonstrating this...