Browse Prior Art Database

COLOR 35MM SLIDE ARTWORK GENERATOR USING VACUUM FLUORESCENT SOURCE

IP.com Disclosure Number: IPCOM000025527D
Original Publication Date: 1985-Dec-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 4 page(s) / 137K

Publishing Venue

Xerox Disclosure Journal

Abstract

One of the functions of reproduction centers is to be able to produce 35mm color slides from computer generated images. Current hardware involves a precision cathode ray tube (CRT) exposure station where three computer generated color separations are exposed in sequence to produce the image. In addition to the technical difficulties of registration, distortion and image stability (exposure takes a finite time), the equipment being used is relatively expensive as well as bulky.

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Page 1 of 4

XEROX DISCLOSURE JOURNAL

Proposed Classification
U.S. C1. 355/18 Int. Cl. G03b 27/00

Frank C. Cenovese

T)rr PHOTO DETECTOR/CLOCK GENERATOR

PLASTIC CONDENSOR LENS

35MM CAMERA LENSES

- -------- -

&-

'PI LOT " LAMP

AND SLIT

 FA ST GALVO MIRROR

*c---

' I t

I

---- -++ -------

35MM CAMERA

SLOW GA LVO

   \ \;r AND MIRROR OPEL GLASS

  VACUUM- *MIXER" FLUORESCENT COMPUTER CONTROLLED LIGHT SOURCE

Volume 10 Number 6 November/December 1985 353

[This page contains 1 picture or other non-text object]

Page 2 of 4

COLOR 35MM SLIDE ARTWORK GENERATOR USING VACUUM FLUORESCENT SOURCE (Cont'd)

One of the functions of reproduction centers is to be able to produce 35mm color slides from computer generated images. Current hardware involves a precision cathode ray tube (CRT) exposure station where three computer generated color separations are exposed in sequence to produce the image. In addition to the technical difficulties of registration, distortion and image stability (exposure takes a finite time), the equipment being used is relatively expensive as well as bulky.

A smaller and cheaper system is disclosed in the figure that comprises a vacuum fluorescent device (VF) customized to expose 35mm film in a system composed of two scanning galvos with position sensing and control, a standard 35mm camera and lens, and a VF device under computer control.

The VCF device in the figure incorporates 3 independent color phosphors deposited on three anodes in the envelope, with three control grids. Light output is control led by 3 digital-to-analog (d-to-a) converters representing the intensity levels of the three phosphors. A feed-back system may be employed to linearize light output of each phosphor. For example, simple circuitry can be devised to serve either the anode current, or the actual light level of each phosphor to the value set by the d-to-a converter. Alternatively, the computer can be programmed to set voltage levels that compensate for the non-linear behavior of each phosphor, with the equivalent of a look-up table for each brightness level determined at the time the system is calibrated.

Since the three phosphors can be operated simultaneously, the image need only be scanned once and perfect color registration is guaranteed. The light from the three phosphors is "mixed" by a diffusing screen and the exposing area fixed by a well defined aperture as shown in the figure. The galvos are designed to scan the image area in a standard raster pattern and may be controlled by a number of straight forward techniques. For example, the reverse side of each galvo mirror can be used to reflect a low power laser beam used in conjunction with optical gratings and associated optics...