International Business Machines Corporation

Douglas E Clancy

Danny Marvin Neal

Carl F Johnson

David J Bowles

William R McCray

Richard Francis Frankeny

George P Olson

The electronic controls for a typewriter disclosed herein allow the operator to erase a character using automatic erase capability such as disclosed in U.S. Pat. No. 3,780,846 and at the same time to remove any underscores associated with that character. When an underscore command is entered the memory which stores the code representing the characters typed is caused to be altered in its content to indicate upon the reading of that code segment that the character has been underscored and that the character must be erased along with the underscore. The apparatus accomplishes multiple erase cycles to remove the underscore and then the character. In proportional space mode of operation it is possible that multiple underscore erase cycles will be necessary to remove an underscore which is wider than the underscore type font on the type element.

Underscore erase

A damping control system for a three phase stepper motor. A reluctance velocity transducer is used for each of the three phases. The output of each of the transducers is proportional to the rotational velocity of the motor. Each of the transducers is rotationally phase shifted 3.75 with respect to one another and phased to the motor rotor rotationally such that the zero voltage crossings of the transducers correspond to the zero torque crossings of the motor. During damping or detenting of the motor the selected phase has current applied to it which is equal to a predetermined fixed value plus the feedback from its associated transducer. The windings on each side of the detent position have current applied to them which is proportional to the voltage from their respective feedback transducers. The voltage in each of the windings is amplified by a selected gain constant. The current in each of the windings is such that maximum torque is applied to drive the motor to the detent position with appropriate current reversals in the windings to damp out any kinetic energy in the rotor during detenting.

Electronic damping of stepper motor

Described herein is a feature and the electronics and logic necessary to implement a paragraph indent feature on an electronic typewriter which is improved and more advantageous than previous routines which accomplished similar results. Paragraph Indent is beneficial to the operator in that it automatically positions the printing carrier at an indented level for setting off typed material so that the left edge of the indented material does not extend to the normal left margin. The typewriter under electronic control stores in memory, upon an appropriate command, a temporary left margin to which the carrier will return when the typewriter is operating under the paragraph indent mode. The operator may enter the Paragraph Indent mode from the keyboard by keying an alternate function or code signal together with a tabulation or tab code signal. This causes the electronics to control the typewriter so as to move the print point to the next tab stop and thereafter until countercommanded will return the carrier to that indented line position on all subsequent carrier returns.

Paragraph indent

On electronic typewriters which have the ability to record into a small working memory those characters, functions and escapements which are keyed at the keyboard, it is many times advantageous to be able to place the carrier and the print point over a character which has been previously typed without using repeated backspaces. Disclosed herein is a feature for an electronic typewriter which permits the operator to easily align the print point with a character on the page by positioning a reference mark on the card holder or print carrier in relation to a previously printed character and then through keyboard control cause the carriage to shift its position such that the print point is then exactly aligned with the character printed. The positioning of the carrier such that the reference mark is in relation to the desired print point is accomplished by a backspace operation and the repositioning or causing of the carrier to assume a position immediately over the subject character is accomplished by keyboard control through the electronics of the typewriter to cause the carrier to shift a predetermined distance.

Relocate feature for an electronic typewriter

On electronic typewriters which have the ability to record into a small working memory the escapement of the characters which are keyed at the keyboard, it is many times advantageous to be able to reposition the carrier at the rightmost end of the typed material automatically. This is particularly advantageous when it has been necessary to back the carrier up along the printed line for purposes of erasing, correcting or inserting material into that line. Disclosed herein is an electronic typewriter which is controlled by the electronic logic such that the depression of a selected control key will result in the carrier moving from a position within the typed text on a particular line to the right most position the carrier has occupied within that line during earlier typing. This is accomplished by temporarily storing the rightmost carrier position as recorded in the escapement register into a working memory and then upon the appropriate command from the keyboard, using that location in the manner that a tab stop location would be used and creating a tab like command movement to cause the carrier to go directly to that point and stop.

Print point reposition feature for an electronic typewriter

An electronic typewriter which has the capability of erasing characters automatically and which has the further improved capability of being able to back through unused space on the line, which results after a tabulation command, thereby allowing the repositioning of the type element over the characters typed prior to the tab command thereby allowing automatic erasure of those characters. The improvement of the typewriter as described permits the retrieving of characters from an electronic memory and the use of that memory to control the erase cycle even where the carrier position and the character to be erased are on opposite sides of space without printed characters due to a tab command. This is accomplished by the electronic control of the mechanical hardware and the ability to determine where the tab command was entered on the typing line and to prevent erasure cycles in the unprinted space until the carrier has returned to the point at which the tabulation command was entered.

Growing community of inventors

Austin, TX, United States of America

Douglas E Clancy