US3852775A

US3852775A - Moving belt scanning printer

Info

Publication number: US3852775A
Application number: US00426985A
Authority: US
Inventors: C Hutchinson; D Cary
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1973-12-20
Filing date: 1973-12-20
Publication date: 1974-12-03
Anticipated expiration: 1991-12-03
Also published as: CA1020789A

Abstract

An optical printer in which light images of selected characters fall on a photosensitive medium. A first endless character belt having formed therein a plurality of characters circumscribes a flash lamp. A second endless aperture belt surrounds the character belt and contains a plurality of spaced-apart openings, the distance between the openings being approximately equal to the length of a printed line of characters. Both of the belts are revolved continuously with the character belt moving at a speed much greater than the speed of the aperture belt such that each character passes the printing aperture at each character print position. By means of a suitable electronic control system, the lamp is flashed at precisely the moment when a desired character is in front of the aperture to direct the selected character image to the photosensitive medium.

Description

United States Patent [191 Cary et al. Dec. 3, 1974 MOVING BELT SCANNING PRINTER Primary Examiner-John M. Horan [75] Inventors: Donald S. Cary, Perinton, N.Y.;

Charles H. Hutchinson, deceased, [57] ABSTRACT late of ROChester,N.Y.,Carol An optical printer in which light images of selected W. Hutchinson, administratrix, characters fall on a photosensitive medium A first Penfield, N.Y. endless character belt having formed therein a plurality of characters circumscribes a flash lamp. A second [73] Asslgnee' g Pg rz g Stamford endless aperture belt surrounds the character belt and y my contains a plurality of spaced-apart openings, the dis- [22] Filed: Dec. 20,1973 tance between the openings being approximately equal to the length of a printed line of characters. [21] Appl' 426985 Both of the belts are revolved continuously with the character belt moving at a speed much greater than [52] U.S. Cl. 354/14 the speed of the aperture belt such that each character [51] Int. Cl B41b 15/06 passes the printing aperture at each character print [58] Field of Search 95/4.5; 354/14 position. By means ofa suitable electronic control systern, the lamp is flashed at precisely the moment when [56] References Cited a desired character is in front of the aperture to direct UNITED STATES PATENTS the selected character image to the photosensitive me- 3,291,015 12/1966 Moyroud 95/45 3 Claims, 3 Drawing Figures 29 z r U D D a i r u n c: n i: ii WHQJQHQ I 1/ 1 D D D i D E! El 0 26 10 a 29 /I 4 I D u n a D I ABCDEFGH/ U E! D I t r 47 n M I MOVING BELT SCANNING PRINTER BACKGROUND OF THE INVENTION High speed non-impact printers are known in the art wherein images of desired characters are projected in rapid succession onto a photosensitive medium to thereby be recorded. Many of these printers utilize character belts or drums in which the desired characters are formed as transparent areas on the belt or drum which is revolved at high speed. In such arrangements. means must be provided to scan the optical images of the characters across the photosensitive medium rapidly and accurately over a prolonged period without misalignment or breakdown.

OBJECTS AND SUMMARY. OF THE INVENTION It is therefore an object of the invention to provide a light beam scanner suitable for use in non-impact high speed optical printers.

A further object is to provide a scanner which is dependable in operation and simple in construction.

A further object is to provide a non-impact optical printer including a scannerwhich is capable of increased printing speed and which is operable for sus tained periods without the need of realignment.

These and further objects of the invention are accomplished by means of a non-impact printer including a light beam scanner in which a first endless character belt having formed therein a plurality of characters circumscribes a flash lamp. A second endless aperture belt surrounds the character belt and contains a plurality of spaced-apart openings, the distance between the openings being approximately equal to the length of a printed line of characters. Both of the belts are rev volved continuously with the character belt moving at a speed much greater than the speed of the aperture belt. Due to the difference in speed between the aperture and character belts, each character on the character belt or in a given set of characters on a portion of the belt passes in front of a printing aperture at each printing position along the printed line. By means of a suitable electronic control system, the lamp is flashed at precisely the moment when a desired character is in front of the aperture to direct the selected character image onto the photosensitive screen.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective diagrammatic view of the moving belt portion of the optical printer of the invention,

FIG. 2 is an illustrative plan view of the printer, and

FIG. 3 is an illustrative front view showing the details of character and aperture belts of the printer.

DESCRIPTION OF THE PREFERRED EMBODIMENT The character belt 10 is made of a thin flexible mate rial sufficiently strong to sustain high speed movement by the above-noted drive system without breaking. The material from which the belt 10 may be opaque except in the areas containing characters, which are formed by cutting character-shaped openings into the belt 10. Alternatively, the character areas may be formed by suitably shaped transparent areas formed in the belt 10. Any variety of characters may be formed on belt 10 including alphanumerics or numerals, as illustrated in the drawing. Several different styles or fonts of letters or numbers may be included on the same character belt 10. The characters on the belt 10 are spaced apart equally, the distance between characters being approximately the desired distance between printed characters.

Adjacent the bottom edge of the character belt 10 is located a margin area in which an optical or magnetic code 26 is imprinted. This code 26 is used to precisely identify the orientation of the belt 10 or the position of each character at any given point in time, as will be explained in greater detail hereinafter. The code 26 is continuously sensed by means of a sensing arrangement 13 of conventional design, which may be either optical or magnetic in nature. An optical sensing system of the type suitable for use with the invention is shown in US. Pat. No, 3,735,042. The sensing arrangement 13 provides a first input to a logic circuit 14.

The character belt 10 moves traverse of or across a flash lamp 16 which is located within the rectangle formed by the character belt 10. The lamp 16 is centered approximately on the horizontal plane intersecting the midpoint of the characters on belt 10 and is arranged, when flashed, to direct a beam of light through the character belt toward an image or focal plane 17 at which is located a movable photosensitive medium 18. Intermediate the image plane and the flash lamp 16 may be located suitable conventionaloptical focusing components 30 to image the selected characters onto the image plane 17.

The time at which the flash lamp 16 is flashed is controlled by means of a logic circuit 14 which accepts input data on the character to be printed from a data input 19 and coding data on the position of the characters at any given moment from the sensing circuit 13. When the character to be printed is suitably positioned, a control signal is developed to momentarily turn on the lamp l6. Suitable logic circuitry for accomplishing this control function is well known in the prior art. The wavelength of the lamp 16 may be chosen to complement the sensitivity of the photosensitive medium 18 which is located at the image plane 17. The photosensitive medium may be a conventional xerographic drum or may be suitable photosensitive paper.

Circumscribing or surrounding the character belt 10 and concentrically located with respect thereto is an endless aperture belt 20. The belt 20 is made of an opaque material which may be the same as the material used for the character belt 10 and is provided with openings 29 cut at spaced-apart distances therein. Al ternatively, the belt may contain transparent areas of suitable shape in place of the apertures 29. The apertures 29 are located at spaced-apart intervals so that as soon as one opening completes its movement in front of the image plane 17, a second aperture belt is about to move in front of the image plane at the opposite end thereof. The distance between the openings 29 therefore substantially corresponds to the length of a line of printed data. The size of the openings 29 are such that only asingle full character may be imaged at one time on the photosensitive medium 17.

The aperture belt 20 is mounted for continuous movement on rollers 21, one or a plurality of which are driven by the same motor 12 through a suitable speed reducing gear arrangement 32. As mentioned in connection with the character belt 10, suitable sprockets holes may be formed in belt 20 to mesh with sprockets in the driven rollers 29' to better accomplish rotation thereof. The aperture belt 20, as noted hereinbefore,

moves at a relatively slow speed with respect to the character belt 10.

In operation, the motor 12 through suitable gearing arrangements drives the character belt and the aperture belt at constant but different speeds with the character belt 10 moving at a speed much greater than thespeed of the aperture belt20.

A stream of digital data is continuously received from an input source 19 (which may be the output of a computer) corresponding to characters to be printed. The

incoming data is fed to a logic circuit 14 which is of conventional design within the capability of one skilled in the art. Simultaneously, coding information related to the position of the characters on the belt 10 is also fed to the logic circuit 14. When the character to be printed is in front of the aperture opening at the proper printing position, the logic circuit develops a control signal which flashes the lamp 16.

It will be appreciated by reference to FIG. 2 that the flashing of the lamp 16 will result in the light projection of one character onto the photosensitive medium 18, via the optics 30. In this fashion successive characters in each line are continuously imaged in rapid succession onto the medium 18.

It should be understood that the photosensitive medium may be moved in a stepped fashion or continuously. In the stepped mode, the paper may be moved one printing line after the passage of one of the apertures 29 across the focal plane. Alternately, the medium 18 may be moved continuously, in which case a slight slant in the printed character would appear which could be cured by suitable slanting the orientation of the belts l0 and 20 and the lamp 16 to compensate therefor.

it should be understood with respect to the drawings, that the spacings between elements are merely illustrative and may be varied somewhat within the teachings of the invention.

What is claimed is:

1. An arrangement for scanning character images across a photosensitive medium comprising:

an endless character belt having formed thereon a plurality of light transmitting areas corresponding to a font of characters,

an endless aperture belt concentrically arranged with and around said character belt and having a por tion thereof located between said medium and said character belt, said aperture belt containing a plurality of light transmitting zones each being spaced from each other at least a distance approximately equal to the length of a printed line of characters to be printed on the medium,

flash illumination means located interior the closed surface formed by said character belt,

means for continuously rotating said character belt and said aperture belt with said character belt moving at a speed greater than said aperture belt and one of said light transmitting zones being located at successive character print positions opposite said medium, and

control means for flashing said lamp successively when selected characters to be printed pass in alignment with the light transmitting zone at each character print position whereby selected characters on said character belt are projected onto said medium.

2. The combination recited in claim 1 wherein said flash illumination means is a lamp which extends the length of a printed line.

3. The combination as recited in claim 1 wherein said means for continuously rotating said belts includes means for interconnecting said character belt with said aperture belt, and drive means operatively connected to said interconnecting means.

Claims

1. An arrangement for scanning character images across a photosensitive medium comprising: an endless character belt having formed thereon a plurality of light transmitting areas corresponding to a font of characters, an endless aperture belt concentrically arranged with and around said character belt and having a portion thereof located between said medium and said character belt, said aperture belt containing a plurality of light transmitting zones each being spaced from each other at least a distance approximately equal to the length of a printed line of characters to be printed on the medium, flash illumination means located interior the closed surface formed by said character belt, means for continuously rotating said character belt and said aperture belt with said character belt moving at a speed greater than said aperture belt and one of said light transmitting zones being located at successive character print positions opposite said medium, and control means for flashing said lamp successively when selected characters to be printed pass in alignment with the light transmitting zone at each character print position whereby selected characters on said character belt are projected onto said medium.