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Bidirectional Printing in a Phototypesetter

IP.com Disclosure Number: IPCOM000074005D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 4 page(s) / 57K

Publishing Venue

IBM

Related People

Bachman, DE: AUTHOR [+2]

Abstract

Shown is a cathode-ray tube phototypesetter capable of printing characters in either the forward direction or reverse direction, or mirror image of characters in either the forward or reverse direction.

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Bidirectional Printing in a Phototypesetter

Shown is a cathode-ray tube phototypesetter capable of printing characters in either the forward direction or reverse direction, or mirror image of characters in either the forward or reverse direction.

Characters are generated by the use of a cathode-ray tube 10 and a reciprocating lens 12. The vertical dimension of the characters is produced by a line scan on the face of the cathode-ray tube 10. The lens 12 horizontally. Thus, a series of line scans with blank/unblank segments will be projected side-by-side on film 14 and thereby produce an image of a character on the film 14.

Display controls 16 provide the signals that control the deflection of the cathode-ray beam and the turning on and turning off of the cathode ray beam. The position of the lens is supplied to the display control over lines 18 and 20. Line 18 carries the margin sense information indicating where the lens has crossed a margin, and line 20 carries tachometer pulses from the motor 22, which drives the lens, so that the position of the lens can be monitored by the display controls.

The blanking and unblanking function of the display controls 16 is accomplished by using a counter to count out segment counts received from the data sequencer 24. These segment counts specify the length of blank and unblank segments in a given vertical scan. In this way, by a series of segment counts, the vertical scans are split into black and white segments. The display control 16 operates with the data sequencer 24 by requesting over line 26 another segment count from the data sequencer. The sequencer then sends a segment count over line 28 and a load display signal over line 30 to display controls 16.

The data sequencer 24 receives the segment counts and arranges these counts for either forward or reverse printing. Thus, the data sequencer needs as input the segment count information from a computer 32 and the forward or reverse direction of the reciprocating lens 12 from the direction sensor 34. If the lens is moving from left-to-right or in the forward direction, the data sequencer can sequence the data in the normal manner. Whereas, if the lens is moving in the reverse direction from right-to-left, the data sequencer will have to rearrange the segment counts from the computer 32 before they are passed forward to the display controls 16.

Direction sensor 34 merely operates off of two transducers 36 and 38 and contains logic to detect and indicate which direction the lens is moving, forward or reverse. The output from the transducers 36 and 38 is also collected by OR 40 to produce a margin indication which is utilized by the display controls 16.

The innerconnection between the data sequencer 24 and the computer 32 provides a conversion whereby character segment counts are sent from the computer over line 42 to the data sequencer 24. In return, when the data sequencer has finished passing a sequence of segment counts to the display con...