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Adaptive Control Circuit for Printer

IP.com Disclosure Number: IPCOM000085824D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 4 page(s) / 40K

Publishing Venue

IBM

Related People

Meier, JH: AUTHOR [+2]

Abstract

In a serial printer having a typewheel on a carrier movable along a print line, the typewheel may be bidirectionally rotated to selectively position a character for printing. If the carrier is to be moving during printing the typewheel should reach its prescribed position immediately before or concurrently with carrier arrival at the print position. This indicates that the carrier velocity along the print line should be appropriately increased or decreased for improved efficiency.

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Adaptive Control Circuit for Printer

In a serial printer having a typewheel on a carrier movable along a print line, the typewheel may be bidirectionally rotated to selectively position a character for printing. If the carrier is to be moving during printing the typewheel should reach its prescribed position immediately before or concurrently with carrier arrival at the print position. This indicates that the carrier velocity along the print line should be appropriately increased or decreased for improved efficiency.

Several carrier velocity profiles are provided so that the carrier arrives at the print location with the required velocity and just after the typewheel has had time to settle out. The carrier velocity profile should be chosen so that the time between the stop pulse for the typewheel and the firing pulse for the print hammer coincides with the required typewheel settle-out time.

The velocity profiles are determined primarily by the typewheel motor and carrier motor capabilities. For example, the carrier motor will require some minimum time to move the carrier from one print position to the next. During this time, the typewheel motor will be able to properly position a character that lays within some predetermined number of typewheel positions from the last printed character. Such time can be considered profile A.

A second group of characters, further displaced from the last printed character, will require more time for the typewheel to be moved and the carrier can be operated at a slower velocity profile B. Perhaps a third group of characters will require that the carrier be moved still slower at a velocity profile C. The carrier velocity may be varied by its acceleration rate or constant-run rate, but the carrier is usually required to be at a predetermined velocity at each instant the print hammer is fired.

The various character groupings for each of the velocity profiles of the character may change with variations in voltage supply or friction, which can either slow or speed up the character selection in the printing process. An adaptive control for changing the character groupings dynamically during operation of the printer is shown in the figure.

Initially, the character groupings are set conservatively. For example, characters within seven typewheel positions of the last printed character may all be selected at maximum carrier velocity, while characters from the 8th thru 14th position may require velocity profile B and so on with the remaining characters corresponding to other profiles.

For each character group, there is established a normal time value Tn in clock pulses indicating the normal move time and this is stored in look-up table
10. Upon selecting a character, the number N of typewheel positions required for the move indicates a value Tn which causes a second look-up in a correction table for delta T at table 11. This correction value is added to time Tn and transmitted to control 12, in which the appro...