US 3622241 A
Description (OCR text may contain errors)
Umte m States Patent  Inventor John L. Dexter 3715 Friar Lane, Santa Barbara, Calif. 93105 [21 Appl. No. 39,257
 Filed May 21,1970
 Patented Nov. 23, 1971 [5 4] ROTARY PHOTOSENSITIVE MATERIAL PRINTER 14 Claims, 6 Drawing Figs.
 U.S.C1 355/110, 355/26. 355/87, 355/91, 355/105  lnt.Cl ..G03b 27/10  Field of Search 355/26, 87, 91,92, 104, 105, 106, 108,110
[ 56] Relerences Cited UNITED STATES PATENTS 2,408,310 9/1946 Hassler 355/1 10 X 2,783,697 3/1957 Eisneret al.. 355/110 3,116,787 1/1964 Campbell 165/90 3,409,364 1 H1968 Moorhusen 355/92 OTHER REFERENCES Primary Examiner-Samuel S. Matthews Assistant E.raminerRichard M. Sheer Attorney-Smyth, Roston & Pavitt ABSTRACT: A photosensitive material printer having a pair of water-cooled ultraviolet light sources situated on opposite sides of a workpiece and a pair of negatives which are passed therebetween. The light sources are each positioned within a tubular roller having a rigid translucent inner wall and a pliable translucent pressure outer wall. Air is delivered to the volume between the rigid and the pliable walls so as to maintain firm, fixed contact between the workpiece and the associated negatives. if desired, one or more deflector rollers may be positioned about the periphery of the outer wall to deform it so as to increase the pressure between the rollers and thereby increase the area of contact between the rollers and the workpieces passing therebetween.
PATENTEDuuv 23 I97! 3.622.241
sum 1 OF 5 PATENTEU 3.522.241
sum 3 OF 5 Arrow 5);;
PATENIEuunv 23 Ian SHEET R [If 5 1 1 1 1 I I 1 1 1 MR 1 1 1 1 1 1 1 1 I 1 1 JR z fizfif BACKGROUND OF THE INVENTION This invention relates to apparatus for exposing a photosensitized material to light which is passed through an exposure device, such as a negative. As the workpiece is exposed to the light, the intelligence on the negative is duplicated on the surface of the workpiece due to the photosensitive material exposure. 7
In the past, flat photosensitized workpieces have been photocontact printed by temporarily creating a fixed phototo-workpiece contact and exposing the combination to ultraviolet light. The contact has been maintained by a variety of techniques, depending on whether the parts are rigid or flexible. For example, diazo paper utilized in manufacturing blueprints is often exposed as it rolls tightly together with its transparent master around a rotating glass cylinder inside of which are located tubular ultraviolet lamps. An example of such a device, for a slightly different application, is shown in US. Pat. No. 2,531,086 issued Nov. 21, l950.
In another basic technique, the photosensitized workpiece and negative are placed into precise registration and positioned within a vacuum frame from which the air is drawn so as to maintain the parts in fixed relationship and firm contact. Relative motion between the contacting parts and an ultraviolet light source causes exposure of the photosensitized workpiece. Such a technique is employed in the invention embodied in U.S. application Ser. No. 877,160, filed Nov. I7, 1969, and assigned to the Assignee hereof.
A wide variety of alterations and combinations of these techniques have been devised in attempting to increase the versatility of printing machines, enlarge the capacity of the machines, improve the accuracy of exposure of the photosensitized material, etc. In almost all instances, the greatest degree of accuracy has been provided by maintaining the workpiece and the negative in a fiat relationship to one another.
Since the vacuum-printing frame technique is limited to use with a workpiece having a fixed length and width, it is relatively slow due to the time required for the vacuum pulldown, it is subject to a lack of uniformity of vacuum pulldown, especially on two-sided exposure frames, it is subject to increased contamination since four surfaces can get dirty on a two-sided printer, etc.
It is generally considered desirable in overcoming these deficiencies to pass the workpiece and the negatives between opposed rollers. In most cases, one roller is formed of a substantially rigid material and the opposed roller is a softer, deformable material so that the workpiece and negative may be firmly held against the rigid roller within which a light source is positioned. Unfortunately, these systems generally cause some deformation of the workpiece so that the registration between the workpiece and the negative is very difficult, if not impossible, to maintain. In an efiort to improve upon these devices, some machines have been manufactured in which the rigid roller is formed of fiat sections or panels upon which the workpiece and negative are positioned. In addition to increasing the cost of the roller, such machines are once again limited to workpieces no larger than the panels since it is not desirable to allow a workpiece to extend across the intersection between two adjacent panels due to the possibility of bending thereof.
In other machines, the rollers are replaced by contacting translucent belts between which a vacuum is formed in the area of contact. These machines have the same deficiencies relative to the uniformity of vacuum pulldown as in the vacuum frame devices.
SUMMARY OF THE INVENTION The present invention comprises a rotary photosensitive material printer having a pair of rollers between which a photosensitized workpiece and a negative, on either or both sides of the workpiece, may be passed for exposure of the photosensitized material. MOre specifically, the invention relates to such a device in which a pair of opposing transparent flexible rollers are utilized to apply a uniform pressure throughout a contact area between the workpiece and the negatives. The contact area includes a strip which is illuminated by reflector-focused light rays emanating from watercooled tubular mercury vapor lamps positioned inside each of the pressure rollers.
The pressure rollers may be fonned as double-walled, tubular cylinders comprising a rigid transparent plastic inner wall or core which is fastened to and surrounded by a flexible transparent outer wall. The inner and outer walls are attached to one another about their peripheries at the axial ends thereof. The volume between the walls is pressurized with a controlled air pressure such that the outer walls are normally maintained in contact with one another.
When a workpiece and one or more negatives are passed between the rollers, the outer walls become deformed in the area of the workpiece so that it may pass therebetween. The temporary deformation of the rollers causes the workpiece and negative to be pressed into a fixed contact which is as rigid as a vacuum-formed contact.
If desired, defomiing rollers may be positioned about the peripheries of the exposure rollers so as to create forces which tend to increase the amount of temporary deformation in the" area of workpiece contact, thereby increasing the overall area of pressure contact between the workpiece and the negatives associated therewith.
The rollers are mounted within a housing which, if desired, may be formed of tinted acrylic sheet so as to prevent stray ultraviolet rays fromescaping therefrom while allowing operator-viewing of the rollers to ensure that dirt or other foreign matter does not contaminate them.
Air driven through two filtered fans may be passed through each inner wall or core of the rollers along the axis thereof to cool them. It may then be passed over the outer roller walls and through the work input and output openings, providing residual heat removal as well as filtered positive air pressure at the printer workpiece input and output, thereby aiding in preventing roller contamination.
Water jackets may be positioned about the light sources to remove infrared energy from the lamp output. If this is not accomplished, the infrared energy might otherwise be absorbed by the rollers and negatives, thereby causing undesirable dimensional expansion, distortion, etc. A compound may be added to the water to increase the absorption of visible light emanating from the lamps. Although this may reduce the amount of ultraviolet light reaching the workpiece by a very small percentage, it will further reduce energy absorbed by the dark areas of the negatives and any collimating devices placed before the lamps.
Other objects and advantages of the present invention will become apparent from the following description and claims as illustrated in the accompanying drawings which, by way of illustration, show a preferred embodiment of the present invention and principles thereof in what is considered to be the best mode contemplated for applying those principles. It is recognized that other embodiments of the invention, utilizing the same or equivalent principles, may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and purview of the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a printing machine formed in accordance with the present invention;
FIG. 2 is a side, schematic illustration of a machine such as that shown in Fig. 1, showing details of the exposure structure;
FIG. 3 is an enlarged sectional illustration of the portions of the rollers at the drive ends thereof in the area in which the rollers intersect;
FIG. 4 is a cross-sectional illustration of the upper lamp assembly and the mounting means therefor;
partially broken away, of
DETAILED DESCRIPTION As shown in Fig. l, a photosensitive material printer 11 comprises a base portion 13 upon which is mounted a control module 15 and a printer cabinet 17. A pair of fans 19 are mounted in the printer cabinet 17 for passing air through filters 21 for a purpose to be described later. A pair of tables or conveyors 23 and 25 may be positioned on either side of the printer cabinet for support of a workpiece and one or more negatives, hereinafter referred to 'as the workpiece sandwich," as they enter and leave the printer cabinet.
With reference now to Fig. 2, the printer cabinet 17 is shown to contain an upper roller 27 and a lower roller 29 which are substantially identical except for minor differences which will be described later. Basically, each roller may be formed to comprise a double-walled cylinder including a rigid transparent plastic core wall 31 and a thin, flexible outer wall 33.
Each roller contains a cantilevered lamp support assembly 35 which faces the workpiece so that a pair of lamps 37 may provide light to a workpiece sandwich 39 passing between the rollers.
A water jacket 41 may be positioned about each of the lamps 37 so as to remove undesirable infrared energy generated by the lamps and prevent undesirable heating of the workpiece sandwich. Each of the lamps is positioned within a suitable reflector 43. A pair of shields 45 are attached to each of the reflectors and, if desired, a baffle or fiber optic plate 47 may be positioned between the edges of shields. The reflector. shields, and baffle will work together to limit the angle at which ultraviolet rays may pass through the negatives to expose the photosensitive material on the workpiece. As the maximum angle between the light rays and a plane passing through the centers of the lamps is diminished by this combination of elements, the amount of undercutting of the intelligence on the negatives will be correspondingly diminished. In other words, the closer the light rays are to being perpendicular as they pass through the negatives, the sharper the delineation ofthe exposure will be.
Each of the lamp supports 35 are substantially T-shaped in cross section and are fastened to one end of the printer cabinet 17 so as to produce a cantilevered support for the lamp assemblies in the manner shown in Figs. 4 and 5. As shown in Fig. 5, each water jacket 41 may be supplied with flowing water passing through an inlet 51 and an outlet 53 which may be connected to any suitable heat exchange system. The water will accomplish the removal of undesirable infrared energy which, in many cases, comprises more than half of the energy output of the lamps. The removal of the infrared energy will prevent the workpiece sandwich from becoming distorted, expanded, etc., by heating. If desired, any suitable chemical substance, such as cupric or cobalt sulfate, may be added to the water to increase the absorption of visible light (blue, green, yellow) which constitutes approximately percent of the lamp energy. Additionally or alternatively, the water jacket may be manufactured of tinted glass. Although these expedients may result in a loss of the desirable ultraviolet energy, such a loss will be very small, while their usage will greatly reduce unwanted energy radiation.
Each end of each water jacket is supported by a mounting device 55 which is fastened to a base 57 by any suitable means such as bolts 59. Each lamp 37 is supported by a pair of end restraints 61 which may be fastened to the mounting devices 55 by suitable means such as bolts 63. Power may be delivered to the lamps by means ofa pair of wires 65.
At each end of the base 57, a pair of wing supports 67 are provided so that the lamp assembly may be adjustably mounted on a lamp support bracket 69 by suitable means such as bolts 71. In turn. the brackets 79 are fastened to the lamp support 35 by suitable means such as bolts 73. As seen in FIG. 2, the lamp support assemblies are identical but are reversed so that both lamps face the workpiece sandwich.
Referring now to Figs. 3 and 6, and particularly to Fig. 3, it can be seen that the core walls 31 of each of the rollers are formed with internal grooves 81 into which split retaining rings 83 may be installed. Clamping rings 85, which are fastened to the split rings 83 by suitable means such as bolts 87, serve to fasten the axial ends of the outer wall 33 against sealing rings 89 which are positioned between the ends of the core walls 31 and the clamping rings. In this manner, the volume between each core wall and its respective outer wall is sealed to prevent leakage of air therefrom.
Bearings 91 are positioned between the roller assemblies and bearing housings 93 which are suitably attached to the printer cabinet 17.
A pinion gear 95 which is driven by a suitable power source (not shown) may be utilized to drive a gear 97 which is formed as an integral part of the clamping ring 85. The upper roller may be driven by friction contact with the lower roller or, as an alternative, a similar gear 99 may be formed as a part of the upper clamping ring 85 to mesh with gear 97.
As shown in Fig. 4, each of the lamp supports 35 also support an air transfer block 113 having a passage 115 therein including an inlet 117 and an outlet 119. Air is supplied to the inlet 117 by means of a hose 121 which is attached to any suitable pressure source (not shown).
A revolvable fitting 123, installed within the outlet 119, is fastened to a hose 125 which is attached to a suitable fitting 127 (Figs. 5 and 6) at the opposite end thereof. In turn, the fitting 127 is attached to a tube or passage 129 which is pressfit into a port block 131 fastened to the internal wall of the core 31 by suitable means such as bolts 133. A passage 135 within the block 131 communicates with the tube 127 and the volume between the walls 31 and 33 by means of an aperture 137 in the core wall 31. In this manner, a pressure may be maintained between the walls of the roller so that the negatives 139 (Fig. 4) may be firmly held against the workpiece 141 of the workpiece sandwich 39.
Referring again to Fig. 2, a plurality of deformation rollers 143 may be positioned about the peripheries of the outer walls 33 of each of the rollers so as to create a larger area of contact between the rollers and the workpiece sandwich 39.
Also as shown in FIG. 2, if desired, the worktables 23 and 25 may be replaced by means of conveyors 147 and 149 to facilitate handling of the workpiece sandwich.
As air is drawn into the printer cabinet 17 by the fans 19, it is passed through filters 21 and then driven through the interior of the inner cores 31. When the air reaches the opposite ends of the rollers, it is turned so as to pass over the outer walls of the rollers and then be exhausted from the printer cabinet through the workpiece inlet and outlet openings, as illustrated in Fig. 2. In this manner, the rollers are cooled by the use of the filtered air and contamination of the rollers is prohibited since the printer cabinet 17 is maintained in a pressurized condition by means of the fans 19. Thus, dirt and other foreign matter are prevented from entering the cabinet and even the workpiece sandwich 39 may be air-cleansed as it passes through the inlet. To further remove incoming dust particles from incoming sandwiches, we can mount air knoves" or antistatic devices 40, in the locations shown in Fig. 2.
If desired, the printer cabinet 17 may include windows of tinted acrylic sheet which will prevent stray ultraviolet rays from escaping from the machine while allowing the operator to view the rollers during operation to further ensure that contamination which might disturb the light rays impinging upon the workpiece sandwich does not occur.
Thus, the applicant has provided an embodiment of a new and improved concept in the photosensitive material exposure art which yields a true advancement in that art. Many further modifications, alterations, and embodiments will be obvious to those skilled in the art without exceeding the scope of the invention as defined in the claims, wherefore what is claimed as the invention is:
l. A photosensitive material printer comprising a base member, a pair of rollers mounted adjacent to one another on said base member for passage of a photosensitive workpiece therebetween, at least one of said rollers comprising an inner hollow core having a wall of relatively rigid translucent material,
means disposed within said inner core wall for exposing a photosensitive material passing between said pair of rollers,
an outer wall of relatively deformable translucent material radially spaced from said inner core wall,
means for sealing the ends of said inner core wall to the ends of said outer wall. and
means creating a pressure intermediate said inner core wall and said outer wall.
2. The printer of claim 1 wherein said means for exposing a photosensitive material passing between said pair of rollers comprises a lamp and means for supporting said lamp within said at least one roller radially inward from said inner core wall.
3. The printer ofclaim 2 wherein said exposing means includes means positioned relative to said lamp for controlling the angles at which light rays impinge upon the photosensitive workpiece passing between said rollers.
4. The printer of claim 2 including means for absorbing infrared rays generated by said lamp.
5. The printer of claim 4 wherein said infrared-ray-absorbing means comprises a water jacket situated about said lamp and flow passage means in said water jacket for passing water through said water jacket.
6. The printer of claim 2 including means for absorbing visible light rays generated by said lamp.
7. The printer of claim 6 wherein said visible light ray absorbing means comprises a water jacket situated about said lamp. means for passing water through said water jacket, and means in the water passing through said water jacket for absorbing visible light rays. 8. The printer of claim 7 wherein said means in the water passing through said jacket comprises a chemical substance which tends to absorb visible light rays while allowing the passage of a substantial majority of ultraviolet light rays generated by said lamp. 9. The printer of claim 6 wherein said visible light ray absorbing means comprises a water jacket situated about said lamp including tinted glass therein for absorbing visible light rays, and means for passing water through said water jacket. 10. The printer of claim 1 wherein said pressure creating means includes an air delivery system and means connected to said air delivery system and the volume intennediate said inner core wall and said outer wall for passage of air into that volume. 11. The printer of claim 1 wherein said pressure creating means includes at least one deformation roller in contact with said outer wall for radial defonnation of a portion of said outer wall. l2. The printer of claim 1 including means for cooling said at least one roller comprising means for passing air through said inner core wall and over said outer wall. 13. The printer of claim 12 including means for filtering the cooling air and means on said base member for preventing the entry of contaminants into the area about the rollers by creating a positive airflow away therefrom 1 The printer of claim I wherein each of said rollers includes an inner hollow core having a wall of relatively rigid translucent material and an outer wall of relatively deformable translucent material radially spaced from said inner core wall, each having an ultraviolet lamp positioned internally of said inner core wall and means for directing the ultraviolet rays generated by said lamps toward the plane in which a workpiece passes between said rollers.