US3693517A

US3693517A - Printing apparatus

Info

Publication number: US3693517A
Application number: US887666A
Authority: US
Inventors: Harold E Clark
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1969-12-23
Filing date: 1969-12-23
Publication date: 1972-09-26
Anticipated expiration: 1989-09-26
Also published as: CA948265A; DE2063213A1; GB1330327A

Abstract

Printing methods and the apparatus therefor are provided in accordance with the teachings of the present invention. According to one embodiment of this invention a radiant energy source selectively transmits radiant energy through a plurality of character patterns arranged in columns and rows. The character patterns are adapted to move relative to the source so that radiation modulated by predetermined ones of the character patterns is selectively applied to a plurality of input paths of an optical positioning means. The optical positioning means includes optical tunnel means which acts to position radiation received at any of a plurality of input paths thereto to a single output location. Photoreceptor means is located at the output location of the optical positioning means whereupon modulated radiation applied to any of the input paths of the optical positioning means is communicated to and imaged upon such photoreceptor means. The photoreceptor means thereby receives modulated radiation corresponding to selected character patterns. The photoreceptor means may then be developed and the images present thereon transferred to print receiving means.

Description

* Q C9 to XR 3 9 6 9 3 9 517 I 1 United mates ra i 3,693,517 Clark Sept. 26, 1972 PRINTING APPARATUS vided in accordance with the teachings of the present 7 Inventor; Harold Clark, penfield, invention. According to one embodiment of this in- 73 A X vention a radiant energy source selectively transmits 1 emx Cowman! Rochester radiant energy through a plurality of character pat- [221 Filed; Dec. 23,1969 terns arranged in columns and rows. The character 21 Appl. No.: 887,666

[52] US. Cl ..95/4.5 [51] int. Cl. ..B41b 21/24 [58] Field of Search ..95/4.5; 340/378 [56] References Cited UNITED STATES PATENTS 3,26l,284 7/1966 Lynott ..l01/114 2,887,935 5/1959 Scott 3,204,540 9/1965 Blakely 3,252,392 5/1966 Ward ..95/4.5

Primary Examiner-John M. Horan Attorney-James J. Ralabate, David C. Petre, Michael H. Shanahan and Marn & .langarathis [57] ABSTRACT Printing methods and the apparatus therefor are propatterns are adapted to move relative to the source so that radiation modulated by predetermined ones of the character patterns is selectively applied to a plurality of input paths of an optical positioning means. The optical positioning means includes optical tunnel means which acts to position radiation received at any of a plurality of input paths thereto to a single output location. Photoreceptor means is located at the output location of the optical positioning means whereupon modulated radiation applied to any of the input paths of the optical positioning means is communicated to and imaged upon such photoreceptor means. The photoreceptor means thereby receives modulated radiation corresponding to selected character patterns. The

1 photoreceptor-means may then be developed and the images present thereon transferred to print receiving means.

5 Claims, 2 Drawing Figures High Voltage v PRINTING APPARATUS This invention relates to printing methods and the apparatus therefor and, in particular, to methods and apparatus for producing printed documents in response to received data signals.

In the printing arts, the two major categories of printing apparatus that have been developed may be classified as impact printers and photoprinters. Conventional impact printers require hammer means to strike a selected character embodied in a character matrix, which selected character is forced into contact with a recording medium, thereby printing a character. Impact printing techniques are exemplified by slow speed, shock and vibration caused by hammer movement, and excessive wear on the mechanical components.

Conventional photoprinter systems act to record images of type composition on a photosensitive medium by the utilization of flashing light emissive elements which image character patterns, physically disposed between the light emissive elements and the photosensitive medium, onto the medium through an optical path including high quality focusing means. Each character pattern may be a member of a font of type in stencil form mounted on a carrier. The carrier may be a rotating drum or disk. As the carrier rotates, each character pattern successively passes between the light emissive elements and the photosensitive medium. If the carrier is a drum, the light emissive elements may be placed within the drum in a stationary position and flashed by a control device as the desired character pattern passes before it. The control device may be a conventional typewriter keyboard, recording tape, punch card, etc. After each character pattern is recorded on a photosensitive medium, such as a galley film, the medium is advanced onecharacter width, resulting in a linear photographic record of the type composition. The font may be mounted on the carrier on a single strip, such as a single circumferential strip for a drum, or a single radial strip for a disk. This results in a large circumference and requires a high speed of rotation of the carrier for efficient photoprinting. The high rotation speed presents problems in synchronizing the flashing light emissive elements to the movement of the photosensitive medium and rotation of the carrier. Those skilled in the prior art have found that the rotational velocity of the carrier may be reduced without affecting the efiiciency of photoprinting by mounting the font on the carrier as a plurality of strips at spaced lateral positions on the circumference of a drum, or at discrete radial positions on a disk.

The location of the character patterns on different strips mounted on the carrier requires a proper positioning between the photosensitive medium, the optical focusing means, the light emissive elements, and the character patterns themselves, in order to obtain proper alignment of the recorded character patterns. Some prior art devices employ fixed optical focusing means, a fixed photosensitive medium and a single fixed light emissive element. The font is mounted on a plurality of parallel circumferential strips affixed to a surface of a drum, and the drum is laterally displaced in a direction parallel to its central axis so as to place the proper character pattern on the corresponding circumferential strip into the correct position with respect to the light emissive element and optical focusing means.

Other prior art devices employ a plurality of light emissive. elements, one for each circumferential strip, and a single fixed optical focusing means. The drum is laterally shifted to place the appropriate font-carrying strip and associated light emissive element into the correct position with respect to the optical focusing means. Still other prior art devices employ a plurality of light emissive elements associated with each strip and displace the optical focusing means into the proper position for imaging a selected character pattern onto the photosensitive medium which is also displaced. The above described conventional photoprinting devices suffer from the common disadvantage of requiring a highly complex and expensive mechanical device for effecting displacement of the carrier, optical focusing.

means and photosensitive medium. In addition, the reliance upon a plurality of mechanical alignment devices to achieve a desired optical path results in high failure rates and requires stringent maintenance.

The aforementioned photoprinting systems record character patterns on a photosensitive medium that is formed into a strip whose width is equal to the height of the largest character patterns. The character patterns are recorded serially and one character pattern is generally recorded for every rotation of the carrier. Other conventional high speed photoprinting devices record character patterns on a photosensitive medium formed into a strip whose width is equal to the width of a printed page. The character patterns are recorded by these conventional devices a line at a time and an entire line of character patterns is recorded for every rotation of the carrier. Thus, if it is assumed that there are character patterns per line, the carrier may be a drum upon which are mounted 80 identical circumferential strips, each strip containing a complete character font. Behind each such character font, and included within the drum, is a light emissive element that is energized when the proper character pattern is brought into alignment therewith as the drum rotates. A separate optical focusing means is positioned between each strip mounted on the drum and the photosensitive medium. As each line of character patterns passes between the light emissive elements and the optical focusing means, selected ones of the light emissive elements are energized when the character pattern aligned in the optical path constitutes the character pattern desired to be imaged upon the photosensitive element. For example, if a row of the letter e" is rotated into position, light emissive elements will be energized whose positions correspond to those where an e is to appear on that line. Although these prior art devices result in accurate, high speed photoprinting, an attendant disadvantage therewith is that the line to be photoprinted must have previously been established, that is, character pattern information for the entire line must first be stored and then read out to flash the appropriate light emissive elements. The line cannot be recorded as it is being composed; it must be in its final form before it is recorded.

Therefore, it is an object of the present invention to provide high speed printing methods and the apparatus therefor.

It is another object of this invention to provide high speed printing methods and the apparatus therefor wherein radiant energy is employed to serially record character patterns on electrophotographic photoreceptor means.

,It is a further object of the present invention to provide methods of and the apparatus for printing at high speeds wherein the density of character patterns on a movable carrier is substantially increased.

It is yet another object of this invention to provide high speed printing methods and the apparatus therefor wherein patterns of radiant energy received at a plurality of points are optically communicated to a predetermined location by optical tunnel positioning means.

It is a still further object of this invention to provide high speed printing methods and the apparatus therefor wherein a plurality of laterally displaced character patterns on a rotating carrier may be selectively imaged upon a predetermined portion of a photoreceptor without any alteration of the optical path or lateral displacement of the rotating carrier.

It is an additional object of the present invention to provide methods of and the apparatus for printing at high speeds while obtaining a reduced velocity of a rotating carrier.

Various other objects and advantages of the invention will become clear from the following detailed description of an embodiment thereof, and the novel features will be particularly pointed out in connection with the appended claims.

In accordance with this invention high speed printing methods and the apparatus therefor are provided wherein an array of character patterns is moved relative to a source of radiant energy such that when the source is selectively actuated, radiant energy is applied through a selected character pattern, modulated thereby and such modulated radiant energy is further communicated to one of several input paths of an optical tunnel means; the optical tunnel means acts to image radiation received at any of the input paths thereto at a singular predetermined output location thereof; photoreceptive means are positioned at such predetermined output location whereby the radiation received thereat may be developed and transferred to print receiving means.

The invention will be more clearly understood by reference to the following detailed description of an embodiment thereof in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of one embodiment of the imaging portion of the printing apparatus according to this invention; and

FIG. 2 shows an embodiment of printing apparatus according to the present invention adapted to illustrate the inventive methods set forth herein.

Referring now to the drawings, and more particularly to FIG. 1, there is shown the imaging portion of the printing apparatus, according to the present invention, for use in high speed printing comprising carrier means 1, a source of radiant energy 13 and optical positioning means 7. Carrier means 1 is adapted to have mounted thereon or otherwise receive a plurality of character patterns in the form of strips or similar presentations of character patterns such as the character patterns of an entire character font, and to move the character patterns relative to radiant energy source 13. In the embodiment of the invention illustrated in FIG. 1, carrier means I is shown as a rotatable drum; however, as will be apparent to those of ordinary skill in the art, the carrier means 1 may also take the form of a disk, an endless belt, or other character-transport means capable of receiving a plurality of character patterns. The character patterns carried by carrier means 1 may be arranged in an array of rows and columns and may comprise the individual characters of an entire character font. The characters may be etched onto the surface of carrier means 1, or, as shown in FIG. 1, may be formed of a plurality of strips, 111-115 wherein each strip comprises a column of character patterns, and the columns are aligned such that a plurality of rows of character patterns appears about the surface of carrier means 1. In the embodiment of the invention illustrated in FIG. 1, five strips 111-115, each bearing a separate portion of an entire character font, are mounted on the circumference of carrier means 1, and the characters are aligned in horizontal rows as shown. It should appear obvious to one skilled in the art however, that the invention is not limited to a single character font, and the strips of character patterns 111-115 mounted on carrier means 1, or the character patterns that may be etched on the surface of carrier means 1, may comprise a plurality of fonts. In addition, although five columns or strips 111-115 are shown, it is clear that the number of columns of character patterns shown in FIG. 1 are for the sole purpose of illustration of the present invention and hence should not be considered as limited to an arbitrary number of columns. However, it should be understood that in the preferred embodiment of the present invention, between five and nine columns of character patterns are to be mounted on carrier means 1. The character patterns of the character font may be selected as opaque patterns on a translucent medium or translucent stencilled patterns on an opaque medium, depending upon the choice of application of the apparatus of the present invention which will be subsequently described. In either event, carrier means 1 should be capable of modulating radiant energy passing therethrough.

As aforesaid, carrier means 1 is adapted to be rotated. For this purpose a motor 15 is mechanically coupled to carrier means 1 by shaft 16. Motor 15 should be capable of continuous, steady-state operation so that carrier means 1 rotates at a constant velocity. Motor 15 may be an ac or d.c. electric motor. In the preferred embodiment, motor 15 rotates carrier means 1 at between and 300 revolutions per second. It is noted that shaft 16 is not the exclusive mechanical coupling device contemplated, and may be replaced by a pulley system, frictional disk, or other mechanical coupling means.

The source of radiant energy 13 may comprise a plurality of conventional light emissive elements 131-135. In the embodiment illustrated in FIG. 1, each light emissive element 131-135 of the source of radiant energy 13 is physically aligned with a single column or strip of character patterns 111-115 and is disposed in the interior of the carrier means 1 along the central axis thereof so as to transmit radiant energy emanating therefrom through the character patterns mounted on the carrier means 1. Light emissive elements 131-135 are designed to produce a burst of high intensity, short duration radiation when energized so that when the image formed by such radiation after the modulation thereof by a given character pattern is ultimately developed, the image obtained will not be blurred and will exhibit high resolution. For this purpose, each of the light emissive elements 131-135 may comprise a gaseous discharge device such as a xenon flash tube, or an arc unit comprised of arcing electrodes. Alternatively, light emissive elements 131-135 may comprise conventional illumination lamps shielded by mechanical shutter means. The choice of light emissive elements 131-135 forms no part of the present invention per se.

The source of radiant energy 13 is electrically connected to control circuitry 17 which acts to cause the selective energization of the various light emissive elements 131-135 therein. Control circuitry 17 may comprise conventional counting and logic gating circuitry to synchronize the flashing of light emissive elements 131-135 to the rotation of carrier means 1. Such circuitry may be entirely conventional and generally the exact nature of the circuitry employed will be a function of the apparatus supplying data to the printing apparatus of the present invention. In addition to synchronization, control circuitry 17 functions to actuate a selected light emissive element 131-135 when a desired character pattern in the column 111-115 associated with that element rotates into the proper position. Control circuitry 17 may, in turn, be controlled by peripheral data signal generators such as a typewriter keyboard, not shown, or punched cards containing data information, information recorded on paper or magnetic tape, or directly by the output of a digital computer. Thus, it will be seen, that the printing apparatus of the present invention has great flexibility with regard to the apparatus from which it may receive data signals and may print data that has previously been generated and stored, or data that is concurrently produced. If the latter application is desired, control circuitry 17 may include still further circuitry that is well known in the prior art to allow for backspacing, corrections, and/or other convenient functions.

Optical tunnel positioning means 7 includes lens 14 and two parallel

planar reflecting surfaces

18 and 19. The planes defined by

surfaces

18 and 19 are perpendicular to the axis of rotation of carrier means 1 illustrated in FIG. 1. Lens 14 is disposed at the input end of the parallel reflecting

surfaces

18 and 19, and the optical axis thereof is longitudinally disposed intermediate the two surfaces. Reflecting

surfaces

18 and 19 may be conventional planar mirrors each having a longitudinal dimension equal to the focal length of lens 14 so as to permit multiple reflections of radiant energy focused thereon by lens M and each having width equal to at least the height of a character pattern. The components of optical tunnel positioning means 7 are disposed such that radiant energy transmitted to the surface of lens 14 over any of a plurality of optical paths may be refracted by lens 14 onto either planar reflecting

surface

18 or 19, depending upon the angle of incidence of the radiant energy passing through lens 14, and reflected by

surfaces

18 and 19 onto a single, predetermined area positioned at the focal plane of lens 14, hereinafter referred to as the imaging position. The precise dimensions of the components of the optical tunnel positioning means are determined by the known optical principles used to design optical tunnels.

The operation of 'th e imaging portion of the printing apparatus illustrated in FIG. 1, will now be described. Motor when energized will couple its rotation to the carrier means 1 through the shaft 16. The angular velocity of the carrier means as driven by the motor 15 may be considered to be at a constant velocity which may be of the order of 300 revolutions per second. As carrier means 1 rotates, control circuitry 17 tracks the characters carried on the surface of carrier means 1 in the well known manner so that the location of each character is known at all times. As data signals are generated by peripheral data equipment (not shown herein) connected to the control circuitry 17, the control circuitry 17 synchronously actuates one of the light emissive elements 131-135 when the character selected by the peripheral data equipment rotates into the proper position. For purposes of the embodiment shown in FIG. '1, the requisite position of a character for the actuation of one of the light emissive element:

131-135 is in a plane perpendicular to the direction of propagation of radiant energy emitted by the light emissive elements 131-135 and coincidental with the focal plane of lens 14. Thus, if the data signals generated by the peripheral data equipment direct control circuits 17 to irradiate a character pattern corresponding to the capital letter B," control circuitry 17 actuates light emissive element when carrier means 1 rotates into the position shown in FIG. 1. The actuation of light emissive element 135 results in the emanation of high intensity, short duration radiation from the light emissive element 135 through the character pattern B which has been rotated into a plane perpendicular to the direction of propagation of radiation emitted by element 135. The radiation emitted from the light emissive element 135 is thus modulated by the character pattern corresponding to the letter B as it propagates radially outward from carrier means 1. Similarly, if the peripheral data equipment selects the letter B, control circuitry 17 actuates light emissive element 134 to produce the emission of high intensity, short duration radiation when carrier means 1 rotates into the position shown in FIG. 1. The radiation emitted by light emissive element 134 will be modulated by the character pattern corresponding to the mirror image of letter E as it propagates through the carrier means 1. The purpose for reversing the character pattern for the letter B is subsequently explained. Control circuitry 17 actuates only one of the light emissive elements 131-135 for each rotation of carrier means 1 so that modulated radiation corresponding to one character pattern is propagated for each rotation. Thus, if carrier means 1 rotates at 300 revolutions per second modulated radiation corresponding to 300 character patterns per second is propagated. The duration of the radiation emitted by each element 131-135 is extremely short in comparison to the velocity of carrier means 1 so that the imaged radiation corresponding to the selected character patterns that are ultimately received and developed will be sharply defined, high resolution images.

The modulated radiation propagated radially outward from the surface of carrier means 1 will traverse an optical path, as indicated in FIG. 1, calculated to cause such radiation to impinge upon the surface of lens 14 of optical tunnel positioning means 7. However, as is readily apparent from FIG. 1, the radiation emitted from each light emissive elements 131-135 will not traverse the same optical path. Thus, since the relame positions of the light emissive elements 131-135 with respect to the lens 14 are fixed, radiant energy will propagate towards lens 14 over one offive independent paths for the embodiment shown, which five independent paths are associated with the light emissive elements 131-135. Depending upon the angle of incidence of impingent radiation, lens 14 may refract such radiation toward either reflecting surface 18 or reflecting surface 19. It is, of course, understood that for impinging radiation that is normal to lens 14, no refraction occurs. In any event, radiant energy received by lens 14, irrespective of its source, will emerge from optical tunnel positioning means 7 at precisely the same location viz., the imaging position. For example, radiation emitted from light emissive element 1.35 will propagate through column 115 and be refracted by lens 14 onto reflecting surface 19. Reflecting surface 19 will reflect this radiation onto reflecting surface 18 from which it will be reflected onto the imaging position. Similarly, radiation emitted from light emissive element 131 will propagate through column 111 and be refracted by lens 14 onto reflecting surface 18. Reflecting surface 18 will reflect this radiation onto reflecting surface 19 from which it will be reflected onto the imaging position. However, radiation emitted from light

emissive elements

134 and 132 will propagate through

columns

114 and 112 respectively, and be refracted by lens 14 onto reflecting

surfaces

19 and 18 respectively, from which reflecting surfaces the radiation will be reflected onto the imaging position. Radiation emitted from light emissive element 133 will propagate through column 113 in a plane perpendicular to the focal plane of lens 14 so that it will be transmitted directly to the imaging position. In view of the foregoing, it may now be observed that radiation emitted from one of light emissive elements 131435 will be subject to a number of reflections equal to the relative lateral position of the light emissive element with respect to the optical axis of lens 14. In other words, a light emissive element that is two positions removed from the optical axis emits radiation that is reflected twice; a light emissive element that is one position removed from the optical axis emits radiation that is reflected once; and a light emissive element that is on the optical axis emits radiation that is not reflected. It is noted that those character patterns through which radiation subject to an odd number of reflections is propagated are represented by their mirror images so that the images of all character patterns communicated to the imaging position will appear in the proper perspective. Thus it is seen, that as carrier means 1 rotates, modulated radiation is applied to the various input paths of the lens 14 by the selective actuation of light emissive elements 131-135 of radiant energy source 13 by control circuitry 17, and the optical tunnel means 7 positions such radiation so that it exits at a single output location thereof. Consequently, the prior art requirement of laterally displacing carrier means 1, radiant energy source 13 or lens 14 is obviated.

The present invention as a whole, an embodiment of which is illustrated in FIG. 2, will now be described. The printing apparatus shown in FIG. 2 comprises an imaging portion, as was described in detail in conjunction with FIG. 1, photoreceptor means 20, developing means 27 and transfer means 32. Photoreceptor means 20 may take the form of an electrophotographic plate comprising a photoconductive insulating body 21 overlying a conductive backing member 22. The photoconductive insulating body 21 is adapted, in the well known manner, to have an electrostatic charge applied to its surface and to selectively dissipate such electrostatic charge upon the exposure thereof to modulated radiation corresponding to a light and dark pattern, such as a character pattern, whereupon a latent image of such pattern is formed. The electrophotographic plate 20 may comprise, for example, a layer of selenium overlying conductive backing member 22. In the illustrative embodiment of FIG. 2, electrophotographic plate 20 is an an endless belt which is deployed around

drive rollers

23 and 24. The endless belt electrophotographic plate 20 has a width equal to at least the largest character in the character pattern array carried by carrier means 1. However, as will be apparent to those of ordinary skill in the art, the electrophotographic plate 20 is not limited to the endless belt configuration shown in FIG. 2, but may take any convenient form such as a drum or web. The conductive backing member 22 may be placed at ground potential by applying ground to drive roller 23 which is in direct contact therewith. In the endless belt configuration illustrated in FIG. 2, electrophotographic plate 20 is translated in the direction indicated by arrow A by the

drive rollers

23 and 24. Electrophotographic plate 20 is adapted to be translated to a cleaning station 31, for a purpose subsequently described, and to charging unit 26. Cleaning station 31 may be of the type described in U.S. Pat. No. 2,751,616 issued to M.I. Turner, Jr., et al. The electrostatic charge applied to the surface of electrophotographic plate 20 may be deposited thereon by charging unit 26 which is electrically connected to a high voltage source 25. charging unit 26 may comprise a corona discharge device of the type described in U.S. Pat. No. 2,777,957 issued to LE. Walkup.

Developing means 27 may comprise any well known form of electrophotographic developing apparatus which acts to develop an electrostatic latent image by the application of electroscopic material capable of adhering to the electrostatic charge pattern on are electrophotographic plate. The nature and composition of electroscopic material is well known in the art as is the manner in which an electrostatic latent image is treated with such material. A more complete description thereof may be found in U.S. Pat. No. 2,885,955 issued to R.G. Vyverberg. It is noted that developing means 27 may include means, if desired, whereby the polarity of an electrostatic latent image may be changed so that the image may be directly developed to form an electrophotographic print corresponding to a photographic reversal of the original exposure. Such means is well known and described in U.S. Pat. No. 2,817,765 issued to R.E. Hayford et al.

Transfer means 32 comprises a print receiving sur' face 28 shown in a drum configuration and positioned so that a surface portion thereof is contiguous with a portion of electrophotographic plate 20. Print receiving surface 28 may be paper, glass, plastic or any surface upon which it is desired to print characters. Developed images are transferred print receiving surface 28 from electrophotographic plate 20 in a well known manner. A charging device, such as corona discharge device 30, may deposit a charge on the back of print receiving surface 28 which is of the same polarity as the charge on electrophotographic plate and is also opposite in polarity to the charge on the electroscopic material utilized in developing the electrostatic latent image. The charge on print receiving surface 28 removes the electroscopic material from electrophotographic plate 20 and onto print receiving surface 28 in the well known manner. Transfer means 32 may alternatively comprise a print receiving surface 28 that is adhesive to the electroscopic material. Once the electroscopic material is transferred to print receiving surface 28, it may be fixed by passing print receiving surface 28 through a heating chamber not shown, whereby the electroscopic material is fused to the surface 28. Although the print receiving surface 28 is illustrated in a drum configuration, it should be clearly un derstood that the drum does not close upon itself and a gap exists between the end portions of print receiving surface 28 as illustrated in FIG. 2. The purpose of this gap will be subsequently explained.

In the operation of the printing apparatus illustrated in FIG. 2 the

drive rollers

23 and 24 translate electrophotographic plate 20 in the direction indicated by arrow A in a well known manner. As electrophotographic plate 20 passes beneath charging unit 26, a uniform electrostatic charge is deposited on photoconductive insulating body 21. The charged electrophotographic plate 20 is translated to a location facing the output of optical tunnel means 7 as shown in FIG. 2. At this location, electrophotographic plate 20 coincides with the focal plane of lens 14- or the imaging position of optical tunnel means 7 and is exposed to the modulated radiation imaged thereat by optical tunnel means 7 in the manner described above with respect to the imaging portion of the present invention described in conjunction with FIG. 1. Exposure of the charged plate 20 selectively dissipates the charge thereon in accordance with the modulated radiation corresponding to the light and dark portions of the character pattern resulting in an electrostatic latent image of the character pattern through which the radiant energy was transmitted. If the character pattern carried by carrier means 1 is in the form of an opaque character on a translucent background, the charge remaining on plate 20 after exposure will be a positive latent image of the character pattern. If, however, the character pattern carried by carrier means I is stencilled i.e., a transparent image on an opaque background, the charge on plate 20 will be a negative latent image of the character pattern. It is understood that the terms positive and negative are here used in their photographic sense. It

is noted that the translation of electrophotographic plate 20 in the direction of arrow A, which is perpendicular to the planes defined by reflecting

surfaces

18 and 19, may be continuous or step-wise. In either case, the distance translated intermittent each discrete energization of one of the light emissive elements 131435 is equal to the width of one character pattern so that the electrostatic latent images on electrophotographic plate 20 will be properly spaced with respect to each other. If, however, the translation of electrophotographic plate 20 is stepped, spaces may be skipped for indentations, tabulation, and ends of lines. Thus, electrostatic latent images of the desired character patterns carried by carrier means 1 are serially recorded on electrophotographic plate 20.

When electrophotographic plate 20 is translated to the developing means 27, the electrostatic latent images are developed to form visible images by well known treatment with electroscopic material. As aforesaid, developing means 27 may include additional means to reverse the images developed thereby. Thus, a negative electrostatic latent image may be developed to form a positive visible image or the converse relationship may be achieved. The developed image is transferred to print receiving surface 28 when electrophotographic plate 20 reaches transfer means 32.

Print receiving surface 23, in drum configuration rotates in the direction indicated by arrow B, whereby it is tangentially contiguous with the surface of the plate 20. The electroscopic material is then transferred to print receiving surface 28 by electrostatic transfer, adhesive transfer, or other conventional electrophotographic transfer techniques. It should be noted that although electroscopic material transfer has here been disclosed in conjunction with the preferred embodiment of the present invention, the electrostatic latent image may alternatively be transferred directly to print receiving surface 28 from electrophotographic plate 20 without the intermediate step of developing the image. If the electrostatic latent image is transferred directly it is developed on print receiving surface 28 by well known techniques similar to those with which the latent image on electrophotographic plate 20 is developed. The rotation of print receiving surface 28 is synchronized with the translation of electrophotographic plate 20; and during one rotation of said print receiving surface 28, a line of characters recorded on electrophotographic plate 20 is transferred to print receiving surface 28. Print receiving surface 28 is advanced by additional means, not shown, in a direction parallel to its axis of rotation for a distance equal to the height of a line of printed characters when the gap between the end portions thereof rotates into the vicinity of electrophotographic plate 20. This permits a new line of characters to be recorded on print receiving surface 28 in the aforedescribed manner. Thus, it is readily apparent, that the images of the characters serially recorded on electrophotographic plate 20 in line configuration are transferred to print receiving surface 28 in page configuration. The gap between the end portions of print receiving surface 28 permits the surface to be advanced as aforesaid without interfering with electrophotographic plate 20. After transfer of the image from electrophotographic plate 20 to print receiving surface 28, plate 20 is translated to cleaning station 31, where any electroscopic material adhering to plate 20 is removed and electrophotographic plate 20 is prepared for re-use in a well known and conventional manner as described in US. Pat. No. 2,751,616. Thus, electrophotographic plate 20 may be of length equal to one line of printed characters whereby the cycle of electrically charging the plate, exposing it to radiant energy, developing the latent image, transfering the image to print receiving surface 28 and cleaning the plate is repeated for each line recorded; or electrophotographic plate 20 may be of any desired length that satisfactorily carries out the above mentioned operations.

Although one application of the present invention has been described with reference to the specific embodiment illustrated in FIG. 2, it is not strictly limited thereto. For example, the width of electrophotographic plate 20 may be greater than the height of one character pattern. In fact, the width of. the electrophotographic plate 20 may be equal to the width of print receiving surface 28. In this case, an entire line of developed images may be transferred simultaneously to print receiving surface 28. Thus, an entire page may be printed for each rotation of print receiving surface 28. To implement this printing technique, carrier means 1 may be positioned such that its central axis of rotation is perpendicular to the plane of the drawing of FIG. 2. In addition, a scanning optical means such as a conventional rotating or traveling mirror may be located at the imaging position of optical tunnel means 7 so that the modulated radiation positioned thereon is scanned across the width of electrophotographic plate 20 thereby depositing a line of latent images of characters on electrophotographic plate 20. Accordingly, the individual characters are serially recorded to form parallel lines of latent images. After developing in developing means 27, each line of character is transferred to print receiving surface 28 as aforesaid. Since an entire page is printed for each rotation of print receiving surface 28, print receiving surface 28 need not be advanced in a direction parallel to its axis of rotation subsequent to each rotation thereof.

It should be apparent to those of ordinary skill in the art that the instant invention admits of a plurality of alterations and modifications which in no way change the basic teachings thereof. For instance, the imaging portion of the present invention may be modified by positioning radiant energy source 13 externally of the carrier means 1 shown in FIG. 1. In this position, radiant energy may be propagated toward the character patterns carried by carrier means 1 and reflected therefrom into the optical path defined by the optical tunnel means 7. In addition, loops may be formed in various positions along the length of belt 20 to compensate, if necessary, for intermittent and continuous motion, or for any of the purpose.

While the invention has been particularly shown and described with reference to a specific embodiment thereof, it will be obvious to those skilled in the art that the foregoing and various other changes and modifications in form and details may be made without departing from the spirit and scope of the invention. It is, therefore, intended that the appended claims be interpreted as including all such changes and modifications.

What is claimed is:

1. Apparatus for printing desired character patterns on a surface comprising:

a plurality of selectively energizable radiation emissive elements adapted to emit radiation of high intensity and short duration,

means for modulating the radiant energy emitted by said radiation emissive elements, said means for modulating including a plurality of character patterns associated with each ofsaid plurality of said selectively energizable radiation emissive elements, each of said plurality of character pattern means being rotatably positionable in an optical path associated with a radiation emissive element;

at least two parallel planar reflecting surfaces disposed in a spaced apart relationship, said at least two parallel planar reflecting surfaces defining a plurality of multiple reflection light paths therebetween;

lens means including a plurality of radiation receiv ing paths interposed between said means for modulating and said at leat two parallel planar reflecting surfaces, each of said plurality of radiation receiving paths being in light communication with one of said plurality of selectively energizable radiation emissive elements and a corresponding one of said plurality of multiple reflection light paths;

a movable belt of photoconductive insulating means having a width equal to at least the height of the largest of said character patterns and disposed in tangential relationship with the focal plane of said lens means, said belt adapted to have a charge deposited thereon, and to have said charge dissipated by said modulated radiant energy communicated to said belt from said at least two parallel planar reflecting surfaces to form electrostatic latent images of said character patterns;

means for developing said electrostatic latent images;

means for transferring said developed images from said belt to a surface operably positioned contiguous to a portion of said belt;

means for rotating said surface about an axis perpendicular to the longitudinal dimension of said belt, and

means for advancing said surface in a direction parallel to its axis of rotation subsequent to each rotation thereof.

2. Apparatus for printing desired character patterns on a surface in accordance with claim 1 wherein said means for modulating comprises:

rotatable drum means having thereon a plurality of columns of character patterns, each of said columns including one of said associated plurality of character patterns and adapted to interpose one of said character patterns in said associated optical path due to the rotation of said drum means; and

means for selectively energizing said plurality of selectively energizable radiation emissive elements in synchronization with the rotation of said drum means when a desired character pattern in one of said plurality of columns of character patterns is rotatably positioned in the optical path associated therewith.

3. Apparatus for printing desired character patterns on a surface in accordance with claim 2 wherein said lens means and said planar reflecting surfaces are disposed in optical tunnel configuration for positioning at the focal plane of said lens means radiation received at said plurality of radiation receiving paths.

4. Apparatus for printing desired character patterns on a surface in accordance with claim 3 wherein said plurality of selectively energizable radiation emissive elements is positioned interiorly of said drum means; and said means for selectively energizing said plurality of selectively energizable radiation emissive elements comprises means to energize one of said plurality of radiation emissive elements during each rotation of said drum means.

f5. Apparatus for printing desired character patterns on a surface in accordance with claim 4 wherein said developing means comprises means for applying electroscopic material to said electrostatic latent images.

Claims

1. Apparatus for printing desired character patterns on a surface comprising: a plurality of selectively energizable radiation emissive elements adapted to emit radiation of high intensity and short duration, means for modulating the radiant energy emitted by said radiation emissive elements, said means for modulating including a plurality of character patterns associated with each of said plurality of said selectively energizable radiation emissive elements, each of said plurality of character pattern means being rotatably positionable in an optical path associated with a radiation emissive element; at least two parallel planar reflecting surfaces disposed in a spaced apart relationship, said at least two parallel planar reflecting surfaces defining a plurality of multiple reflection light paths therebetween; lens means including a plurality of radiation receiving paths interposed between said means for modulating and said at least two parallel planar reflecting surfaces, each of said plurality of radiation receiving paths being in light communication with one of said plurality of selectively energizable radiation emissive elements and a corresponding one of said plurality of multiple reflection light paths; a movable belt of photoconductive insulating means having a width equal to at least the height of the largest of said character patterns and disposed in tangential relationship with the focal plane of said lens means, said belt adapted to have a charge deposited thereon, and to have said charge dissipated by said modulated radiant energy communicated to said belt from said at least two parallel planar reflecting surfaces to form electrostatic latent images of said character patterns; means for developing said electrostatic latent images; means for transferring said developed images from said belt to a surface operably positioned contiguous to a portion of said belt; means for rotating said surface about an axis perpendicular to the longitudinal dimension of said belt, and means for advancing said surface in a direction parallel to its axis of rotation subsequent to each rotation thereof.

2. Apparatus for printing desired character patterns on a surface in accordance with claim 1 wherein said means for modulating comprises: rotatable drum means having thereon a plurality of columns of character patterns, each of said columns including one of said associated plurality of character patterns and adapted to interpose one of said character patterns in said associated optical path due to the rotation of said drum means; and means for selectively energizing said plurality of selectively energizable radiation emissive elements in synchronization with the rotation of said drum means when a desired character pattern in one of said plurality of columns of character patterns is rotatably positioned in the optical path associated therewith.

5. Apparatus for printing desired character patterns on a surface in accordance with claim 4 wherein said developing means comprises means for applying electroscopic material to said electrostatic latent images.