International Business Machines Corporation

Patricia A Graham

Darell Dean Cronch

John K Brown, Iii

John E Passafiume

Richard T Fisher

Kevin N Tucker

A function for an electronic typewriter is described which allows the operator of the typewriter to realign the print element of the typewriter to the prior adjacent, or the following adjacent line which contains textual material, even when the present position of the print element is other than a uniform line feed increment or multiple thereof, from the designated destination line. The electronic controls of the typewriter determine the present position of the print element and the vertical location of the line to which the print element is to move, and determines the distance and moves the record sheet to position the print element precisely over the designated line of text.

Line find feature for an electronic typewriter

By examining parity for a bit combination representing the present phase state of a stepping motor, a selection can be made as to which phase state should be changed in order to produce rotation of the step motor in a predetermined direction. By including within the parity determination not only the present phase state of the stepping motor, but the logic level of a direction bit (DIR), appropriate phase sequence for either CW or CCW rotation can be selected. In a hardware embodiment of the invention, a conventional parity generator module is used with inputs representing the present motor phase states as well as a logic level for a DIR bit. The output of the parity generator then determines which phase state to change to produce the desired rotation. In a software embodiment, a digital computer dedicates a phase state byte with a bit from each motor phase state and an additional DIR bit. Parity can be determined using a conditional branch on parity instruction or merely summing the phase direction byte. In either event, the state of the motor phase is changed depending upon the result of the parity determination in order to produce the desired rotation.

Phase sequencer for stepping motor

For step motors positioned in response to an external reference location, correction for potential one step misalignment is provided. The method and the apparatus of the invention provide a read/write memory, for storing therein a phase state of the step motor at a particular location, e.g. a home position. The home position may coincide with the external reference location or may be offset therefrom by some predetermined move of the step motor. During cold starts, where memory is not retained, the step motor is moved to its home position and then the phase state of the machine is saved. On subsequent warm starts, after the step motor is moved to the assumed home position, the step motor is controlled to assume the phase state that has been previously stored.

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Lexington, KY, United States of America

Patricia A Graham