US3531201A - Preprocessor - Google Patents

Description

Sept. 29, 1970 R. E. PRENTICE PREPRO CES SOR 2 Sheets-Sheet 1 -Filed April 11. 1968 Russell E.Prenfice,

INVENTOR GOLOVE a KLEINBERG ATTORNEYS.

R. E. PRENTICE PREPROCESSOR Sept. 29, 1970 2 Sheets-Sheet 2 Filed April 11. 1968 Utili zoiion Device Russell Ej'Prenric INVENTOR.

GOLOVE & KLYEINBERG,

ATTORNEYS.

United States Patent Int. Cl. G03b U.S. Cl. 355-133 4 Claims ABSTRACT OF THE DISCLOSURE Apparatus cleans positive and negative film stock prior to being placed into intimate surface contact utilizing pairs of opposed radioactive ionizers and opposed brushes which intercept the positive and negative film for removing contaminants from the film surfaces. The positive film, where appropriate also pass over a preexposer, which controllably preexposes the raw positive prior to a contact printing step. A high capacity vacuum line pulls a large volume of air at high velocity across the film surfaces, transverse to the direction of film travel, to sweep surface contaminants from the vicinity of the film, to continuously agitate the brushes to prevent the retention of contaminants and to cool the preexposer light source.

The present invention relates to film processing devices and more particularly to apparatus for cleaning developed negative, and raw positive film stock, prior to their combination for use in a contact printer and, in the case of positive film which should be preexposed for heightened sensitivity, for selectively preexposing such raw film stock, prior to the combination with the negative film.

It has long been known that it is desirable, prior to bringing negative film and raw positive stock into intimate surface contact and before application to a contact printer, for both films to be thoroughly cleaned of all surface contaminants. Since, in contact printing applications it is imperative that the negative and positive film be in as intimate contact as is possible, any particulate matter, which could either scratch or deform the film while being processed, or which would result in a local separation between the positive and negative films, should be removed from the immediate environment.

It is known that the phenomenon of static electricity can and does provide substantial forces of mutual repulsion which tend to repel surface contaminants, and accordingly, radioactive ionizers are used for film cleaning. It is also known, in connection with certain types of positive film stock, such as that which is sold under the trademark Kalvar and which is produced by the Kalvar Company of New Orleans, La., that some uniform, limited preexposure of the raw stock, before the printing step is undertaken, increases the sensitivity of the film. While the exact explanation of this phenomena is not known, it is believed that a certain hysteresis or inertia may exist in the response of the positive emulsion to actinic radiation. The preexposure step tends to provide energy to the emulsion, which, although insufiicient to cause noticeable exposure, reduces the quantum of additional radiation necessary to provide a good quality print.

Prior art devices have been available to apply an electrostatic charge to the film surface. Other devices are available to clean particulate matter from the surface of the film. An air squeegee is available that wipes the surface of the film with a flow of air directed at the surface. In those applicatitons where preexposure of the positive film is desirable, simple preexposers can be provided. However, there has been a need for a single device which can effectively perform all of these functions and, after the positive and negative films are cleaned, charged and the positive preexposed, immediately bring the positive and negative films into intimate contact for subsequent application to a contact printer or other utilization device.

According to the present invention, a high volume flow of coolant, such as air, is provided, across the surface, transverse to the direction of film travel, to remove any contaminating matter from the vicinity. Radioactive ionizers and brushes are provided to remove contaminants from the film surface. The high velocity, high volume air flow also vibrates the brushes to clean them of any matter accumulated therein. Further, the air flow can be utilized to cool the light source which is necessary for the preexposure step.

In a preferred embodiment, a negative film path and a positive film path are provided through a preprocessing unit. Interposed in both film paths at a first station are radioactive polonium ionizing elements which impart an electrostatic charge to the film surfaces. At a second station, opposed brushes contact both surfaces of the film to sweep" any remaining contaminants from the film surfaces. A third station is provided in the path of the positive film, at which station a preexposer is placed. The preexposer has an adjustable exposure slit so that an appropriate amount of actinic radiation can impinge upon the raw stock, relative to the rate of film travel.

A protective housing partially encloses the film path and stations, but is open to the surrounding environment along the line of film travel. The back of the apparatus is substantially open and is coupled into a vacuum system capable of handling a high volume of air at relatively high velocities, assuming the environment is at normal atmospheric pressure.

In specialized applications, it may be desirable to maintain the film in an inert gaseous environment under which circumstances either the vacuum connection is made, or, the back of the apparatus is connected to a source of fluid under pressure, so that a high velocity fluid flow in a direction transverse to the direction of film travel is available. By use of the term fluid both liquids and gases are intended, and, in appropriate applications, either may be employed. In embodiments wherein the preexposer is included, the fluid flow path includes the radiation source for cooling purposes.

While the preferred embodiment of the present invention is intended for use in conjunction with high speed continuous contact printers for film, it is clear that the present invention could be adapted for any high speed winding and reeling systems in which the surfaces of one or more webs must be subjected to a cleaning step to remove surface contamination.

The simultaneous application of a high-volume fluid flow in a direction transverse to Web travel, with a brush station and/or a static-charging station, tends to sweep surface contaminants out of the area of web travel. The high volume fluid flow also agitates the brushes to keep them free of contaminants, and to release any contaminants that might be entrapped by the bristles thereof.

The novel features which are believed to be characteristic of the invention, both as to organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawings in which several preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.

FIG. 1 is a perspective view of preprocessing apparatus according to the present invention, in which unexposed 3 positive film stock traverses the upper path and negative film traverses the lower path;

FIG. 2 is a side view of the apparatus of FIG. 1 with the protective shroud removed; 7

FIG. 3 is a side sectional view of a preexposer unit useful in the present invention; and

FIG. 4 is a top view of a section of the apparatus of FIG. 2 taken along line 4-4 in the direction of the appended arrow.

Turning first to FIG. 1, there is shown in perspective, a preprocessor for film, according to the present invention. As shown, raw positive film 12 is inserted through a first opening 14 in the shroud 16 of the processor 10 and negative film 18 is applied through a second opening 20 in the shroud 16. While not a part of the present invention, it may be noted, that the positive and negative film stock 12, 18 come from separate supply sources (not shown) and, upon their exit from the preprocessor 10, are applied to an idler 22, at which point they are combined in intimate surface-to-surface contact for subsequent application to a contact printer (not shown) or other utilization device.

It is contemplated that the preprocessor 10 and the associated processing apparatus (not shown) will be located in a relatively normal atmospheric environment at normal temperatures and pressures. However, for certain premium applications it may be desirable to house all the equipment in a dust-free, clean environment, where humidity, temperature and pressure are carefully controlled.

In such an application, the preprocessor 10, as shown in FIG. 1, can be connected either to a source of relatively low pressure, such as a vacuum line (not shown), or, it can be connected to a source of high pressure (not shown). In either eventuality, the fluid flow path will be substantially the same and only the direction of flow will be affected. In the preferred embodiment of FIG. 1, a connection is made to a high volume, vacuum line and the direction of air flow is into the drawing.

A preexposure control knob 24 is provided which manually controls an exposure aperture of the preexposure unit, to be explained in greater detail in connection with the figures below. Only partially seen in FIG. 1, are radioactive ionizers 26 for applying an electrostatic charge to the film surfaces, and opposed brush pairs 28, for physically sweeping contaminants from the surface of the film. These are described in greater detail in connection with FIGS. 2 and 4, below.

Turning next to FIG. 2, there is shown a side view of the preprocessor 10, with the front of the shroud 16 removed. The raw positive film 12 passes through the opening 14 and, at a first station, between radioactive ionizing units 26 which are commercially available and which utilize a radioactive source, such as polonium, to create a static electrical charge on the surface of the film 12. The creation of such a static charge induces mutually repelling forces in the film and in any contaminants that may be on the film. Such contaminants, when released from the film surface, are swept across the film by the high velocity air which traverses the film path. With respect to FIG. 2, the path of air travel would be perpendicular to the plane of the drawing.

The air flow in the preferred embodiment is effected by the use of a large chamber or plenum 17 which is connected to the vacuum source. The openings 14, 20 in the shroud 12 extend in the direction of the film path and communicate with the environment.

With the vacuum system operating, a low pressure exists in the plenum 17, and the gradient to exterior, atmospheric pressure creates an air flow through the openings 14, 20 across the films 12, 18 and into the plenum 17.

In alternative embodiments, the back of the preprocessor 10 could be fitted with a modified plenum, adapted to supply air under greater than atmospheric pressure which would flow out of the openings 14, 20.

The film 12 continues between a pair of opposed brushes 28 which scrub the film surface for any contaminants not released by the static charge. The high velocity air flow maintains the bristles 30 of the brushes 28 in a state of constant agitation, thereby preventing the entrapment of any contaminant particles in the bristles 30.

The path of the positive film 12 then traverses a third station which includes a preexposure drum 32, described in greater detail in connection with FIG. 3 below. The drum 32 is connected to the preexposure control knob 24 of FIG. 1, and includes a radiation source 34, in the preferred embodiment an ultraviolet lamp, an inner apertured cylinder 36 and an outer apertured cylinder 38. The inner and outer cylinders are concentrically arranged and are rotatable relative to each other.

As shown, the outer drum 38 is relative the preprocessor 10 and has fixed a wide aperture 40 provided therein. The aperture may subtend an arc of approximately 45 to 60 although the size is not critical. The inner cylinder 36 rotates relative to the outer cylinder 38 and includes an aperture 42 of comparable width. The unapertured portion of the cylinder 38 is arranged to occlude and mask the aperture 40. By suitable rotation of the control knob 24 of FIG. 1, the inner cylinder aperture 42 is rotated, providing an adjustable slit which ranges from fully closed to fully opened. In operation, the setting is determined by the intensity of the radiation source 34, and by the relative lateral speed of the films through the preprocessor 10.

The negative film 18 traverses a similar path. After entering at the aperture 20, the path includes the first station and the radioactive ionizers 26' and the opposed brush pairs 28' at the second station. The negative film '18 is arranged to pass below (as seen in FIG. 2) the drum 32, and is not subjected to any actinic radiation therefrom. Since the high speed fluid flow transverse to the direction of film travel, extends through the entire preprocessor 10, a flow through and preexposer drum 32 in the axial direction keeps the drum and the radiation source sufiiciently cool so as not to adversely affect the negative film 18.

Turning next to FIG. 3, there is shown, in somewhat greater detail, a preexposer drum 32 suitable for use in the present invention. As shown, the drum 32 includes an outer cylinder 38 and an inner cylinder 36. Concentric with the inner cylinder 36 and rotatable therewith is a reflector member 44 which is substantially cylindrical I and which has an aperture 46 that is at least coextensive with the wide aperture 42 of the inner cylinder 36.

The radiation source 34 is shown eccentrically mounted with respect to the drum 32, but its location is primarily a matter of design choice. The outer cylinder 38 is anchored to the frame of the preprocessor 10 and the inner cylinder 36 which is rotatably supported by the outer cylinder 38, is connected to the control knob 24 and is rotated by the knob. By appropriate adjustment of the control knob 24, the aperture 42 of the inner cylinder 36 can coincide with as much or as little of the aperture 40 of the outer cylinder 38 as is required, thereby providing an adjustable width slit for the correct preexposure of the positive film stock 12.

In FIG. 4, there is shown, diagrammatically one surface of the negative film 18 as it traverses the negative film path. The locations of the ionizers 26', the brush pairs 28' and the airflow path relative thereto are all indicated in FIG. 4. It will be clear that if a suflicient volume of air is moved at a high velocity, all contaminants released from the surface of the film can be completely removed from the vicinity of the film surface.

Within the art of winding and reeling, it may be desirable to process a web entirely within a liquid fluid medium. In such applications, it still may be appropriate to provide opposed brushes to clean the surface of the web and to provide a high velocity flow of fluid transverse to the direction of web travel for removing contaminants from the vicinity of the Web. Accordingly, the present invention need not be limited to film preprocessors but may have more general utilization in the art of winding and reeling and in the cleaning of continuous webs as a preliminary step in a fabrication process.

What I claim as new is:

1. In conjunction with an extended web, a web surface cleaner adapted for relative motion with respect to the web in the direction of web extension, comprising in combination:

(a) shroud means tending to enclose the web and having a longitudinal opening substantially parallel to the web;

(b) cleaning means connected to said shroud means and positioned in the path of relative motion, for removing contaminants from the web surface;

(c) removal means including differential fluid pressure means arranged to provide a fluid pressure difference transverse to the path of relative motion and across the surface of the web, whereby a high volume fluid flow traverses the web surface and said cleaning means for sweeping contaminants therefrom; and

(d) preexposing means in the path of relative motion, said preexposing means being positioned to be cooled by the fluid flow.

2. Apparatus of claim 1 wherein said cleaning means include a pair of opposed brushes at a first station positioned to contact opposite web surfaces and opposed radioactive sources positioned adjacent opposite web surfaces, and said removal means are adapted to be connected to a high volume, vacuum source, said fluid being air, the air flow maintaining said brushes in an agitated state.

3. A film preprocessor for cleaning the surfaces of positive and negative film stock prior to their application to a utilization device comprising in combination:

(l) shroud means for substantially enclosing the preprocessor, said shroud having openings extending in the direction of film travel;

(2) cleaning means positioned adjacent the film surfaces for removing contaminants therefrom;

(3) sweeping means including differential fluid pressure means for providing a high volume fluid flow through said shroud openingsin a direction trans verse to the direction of film travel for transferring contaminants from the vicinity of the film surfaces and for removing contaminants from said cleaning; means; and

(4) preexposing means in the path of film travel said preexposing means being positioned to be cooled by fluid flow.

4. Apparatus of claim 3 wherein said sweeping means are adapted to be connected to a high volume, vacuum source, said fluid being air and said cleaning means include at a first station adjacent the path of film travel, first and second opposed brush pairs respectively contacting the positive and negative film said brush pairs being positioned to be agitated and cleaned by said air flow, and said cleaning means further include at a second station adjacent the path of film travel first and second opposed pairs of radioactive sources for applying an electrostatic charge to the surfaces of the positive and negative films, respectively.

References Cited UNITED STATES PATENTS 6/1956 Walkup et al. 151.5 4/1964 Hanscom et al 15-100 NORTON ANSHER, Primary Examiner D. I. CLEMENT, Assistant Examiner

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