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Forms Alignment and Vernier Control

IP.com Disclosure Number: IPCOM000073860D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 3 page(s) / 83K

Publishing Venue

IBM

Related People

Leavenworth, RL: AUTHOR

Abstract

In high-speed line printers the physical complexity of the hardware in the printing area prevents the operator from visually aligning forms accurately. Proper paper position, however, can be achieved with the addition of position hardware and a microprogram. Vernier Control is necessary when incremental raising or lowering of forms is required to precisely locate printing on preprinted forms.

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Forms Alignment and Vernier Control

In high-speed line printers the physical complexity of the hardware in the printing area prevents the operator from visually aligning forms accurately. Proper paper position, however, can be achieved with the addition of position hardware and a microprogram. Vernier Control is necessary when incremental raising or lowering of forms is required to precisely locate printing on preprinted forms.

The hardware added consists of a carriage motor position sensor or emitter and a Forms Length Control Bit, called (X), located in the Carriage Control Buffer (CCB). The position sensor is required to define a "Home" or load point position of the carriage. The Forms Length Control Bit (X) is likewise a sensor added to the CCB by the programmer to detect the last printable line of a form. A Vernier switch with associated logic in F is used to vary the Page Length (PL) count stored in the Space and Skip Counter (SSC). A Page Repeat switch permits the same page of data to be printed repeatedly. This hardware in conjunction with a stored control microprogram routine performs the Forms Alignment and Vernier Control operation.

In A, the fixed load point is designated as the top tractor pin. Forms are loaded so the first feed hole following a fold is placed over the top tractor gin. The tractor pins are on one-half inch centers and with a 2 1/2 degree incrementing carriage motor, for example, 24 steps represents a 60 degree shaft rotation and is equivalent to one-half inch of forms movement. The distance from this load point to the print position is a fixed distance and can be stored as a count of 2 l/2 degrees motor steps by the control program. Thus, by storing the physical location of the forms and the length of each form, the paper can be advanced to the proper position for the first line of print by means of the microprogram.

B is a flow diagram showing what is done by the operator. C illustrates three different size forms. The location of the first line to be printed is determined by the equation: F = PL + Alpha - C < PL where

F = Distance forms move to 1st print line measured by a count

of 2 1/2 degrees carriage motor increments.

PL - Page Length

Alpha - Distance from fold to first print line

C - Constant representing distance from load points to

print mechanism. When C is larger than the Page Length (PL), as in the case for short forms, printing will not start on the second form, but some succeeding form, as shown in C. In the equation for F, if C > PL, called C', then C' must be reduced by

PL's until C < PL,

C = C' - n PL where n is a whole number. Illustration of the equation with the Standard Form in C is as follows: PL = 528 = 11 inch form: x 4h - 2...