US3401617A - Apparatus for making copies by contact printing - Google Patents

Description

J. M. RAIT 3,401,617

APPARATUS FOR MAKING COPIES BY CONTACT PRINTING Sept. 17, 1968 Filed May 18, 1967 INVENTOR. Joseph M. Rolf A TORNEY 23 Fig.2

United States Patent Office 3,401,617 Patented Sept. 17, 1968 3,401,617 APPARATUS FOR MAKING COPIES BY CONTACT PRINTING Joseph M. Rait, 25 Huxley Drive,

Snyder, N.Y. 14226 Continuation-impart of application Ser. No. 488,975, Sept. 21, 1965. This appiication May 18, 1967, Ser. No. 639,402

3 Claims. (Cl. 95-775) ABSTRACT OF THE DISCLOSURE An apparatus for making exposures in direct contact printing. A stationary, transparent cylinder is mounted in a frame, and a tubular light Source positioned concentrically through the cylinder. A flexible plastic sheet extends around the cylinder and is adapted to hold an original paper and a sheet of light-sensitive copy paper securely against the surface of the cylinder. Magnetic closure means maintain the sheet in this position. Light measuring and registering means may be provided to control the duration of exposure of the paper.

This application is a continuation-impart of copending application Ser. No. 488,975, filed Sept. 21, 1965.

The present invention relates to a compact, inexpensive contact exposure apparatus for rapidly producing prints from papers desired to be copied. More particularly, it relates to an apparatus for making exposures in direct contact printing, the apparatus being of relatively simple construction but being capable of providing permanent, accurate, legible copies. While the invention is useful in various kinds of direct contact printing, it is particularly suitable in diazotype printing processes.

In recent years, many machines have been available commercially for producing copies of original papers by direct contact printing, such as by the diazotype and similar processes. However, the copying machines which have been commercially available heretofore generally are complex in construction, containing numerous and complex moving components such as rotating cylinders, cooling apparatus, rollers, feed controls, fans, belts, motors, and the like. For example, one type of direct contact printing machine presently available uses mercury vapor lamps or quartz arc lamps as the light source, making it necessary to provide forced air cooling apparatus in the machine since these lamps give off a considerable amount of heat. Another type of direct contact printing machine presently available contains a revolving glass cylinder, mounted on rollers and driven by motor means, as the contact surface, with a plurality of lamps being disposed inside the cylinder to provide illumination. As a result of this complex construction, such copying machines are relatively expensive to purchase, operate and maintain. Thus an initial investment of from several hundred dollars up to several thousand dollars may be required. In addition, the maintenance of these complex machines may be quite costly, for since they contain numerous moving parts they are subject to mechanical breakdown and failure. Consequently, such presently available contact printing machines are used primarily by libraries, schools, large ofiices in business, industry and government and other establishments which require the frequent use of such machines in order to provide copies of many documents and can thereby justify the cost of purchasing, using and maintaining these machines. These expenses, however, preclude many individuals who may only infrequently need to make copies of papers, such as small business owners, individual homeowners, doctors, attorneys, students, and the like, from using such machines. Therefore,

there is a present need for a contact printing apparatus which is relatively simple to operate and can produce permanent, accurate, legible copies, but which is inexpensive to purchase, operate and maintain.

It is therefore an object of the present invention to provide a contact copying apparatus which is relatively inexpensive to purchase, operate and maintain.

Another object is to provide a compact, inexpensive Contact printing device which can be used by operators having no special training, the device being capable of providing permanent, accurate, legible copies.

Another object of the invention is to provide an apparatus for making exposures in direct contact printing, the apparatus being of relatively simple construction and having no moving parts.

Another object is to provide an economical, eflicient contact printing apparatus, having a novel pressure means for applying good overall contact between the paper to be copied and the light sensitive copy paper.

A further object of the invention is to provide a direct contact copying apparatus capable of producing copies by the diazo process, the apparatus having a single tubular light source with the radiation emitted from the entire circumference of the light being utilized in exposing the light sensitive copy paper.

Another object is to provide an exposure apparatus, for use in making direct contact prints, having photosensing means for determining the proper duration of exposure in making prints.

Various other objects will appear from the following description of the invention, and the novel features will be particularly pointed out hereinafter in the appended claims.

The apparatus of the present invention is a device for making exposures in direct contact printing and is particularly suitable for use in diazotype printing processes. The apparatus consists essentially of a generally rectangular, rigid frame having a stationary, transparent, cylindrical contact surface, longitudinally disposed therein, with the contact surface being fixedly held in position above the bottom surface of the frame. A single tubular light source is mounted concentrically within the cylindrical contact surface, with the cylindrical surface extending over at least that portion of the tubular lamp k which has a relatively uniform output, thereby providing substantially uniform radiation over the entire area of said contact surface. Since the contact surface surrounds the tubular lamp, substantially all of the radiation emitted from the entire circumference of the lamp is directed toward the contact surface and used in the exposure. A flexible pressure means extends around the contact surface over the length thereof, one end of the pressure means being movable away from the contact surface so that the paper to be copied and lighbsensitive copy paper may be inserted between the pressure means and the contact surface. Closure means are provided to maintain the pressure means around the contact surface and hold the papers securely in position.

Thus, the exposure apparatus of this invention is relatively simple in construction and contains no complex moving components. As a result, the apparatus is not subject to mechanical breakdown as frequently in copying machines presently available. In addition, the relatively simple construction of the present device makes it possible to manufacture and market this device at a cost far less than direct contact copying machines now available, thereby making it available to individuals who may only occasionally desire to make copies of original papers but who are unable to afford or justify the cost of the relatively expensive copying machines now available. Despite the relatively simple construction of the apparatus of this invention, it is highly efficient in operation and is capable of producing permanent, accurate, legible copies of original papers. Furthermore, the components of this exposure apparatus are arranged in such a manner that uniform illumination is provided over the entire contact surface by the single tubular light source so that it is not necessary to use a plurality of lamps and/or reflectors as are frequently required in presently available copying machines. Substantially all of the illumination emitted by the tubular lamp passes through the contact surface and is utilized in making the exposure. The single light source used in the present device provides the additional advantages of low cost, long service life, low lamp renewal cost and low power consumption.

According to a preferred embodiment of the invention, the exposure apparatus is also provided with photosensing means for determining the proper duration of exposure in the copying process, and a timer which controls the light source. The photosensing means may consist of a photoelectric sensor system, or a nonelectrical light measuring system, as will be described in more detail hereinbelow. These photosensing means permit even an inexperienced operator to rapidly produce prints having the proper degree of exposure each time.

In order to more clearly describe the present invention, the following is a description of the preferred embodiment illustrated in the accompanying drawings, wherein:

FIGURE 1 is a perspective view of the exposure apparatus of the present invention showing the compact construction of the device and two embodiments of the nonelectrical light measuring system for determining the proper exposure time to be used in making prints.

FIGURE 2 is a sectional view of the apparatus taken through lines 2-2 of FIG. 1.

FIGURE 3 is a longitudinal sectional view of the apparatus taken through lines 3-3 of FIG. 1, in which an electrical sensor system is used for determining exposure time.

Referring now more particularly to the drawings, there is illustrated an exposure apparatus incorporating the concepts of the present invention. The apparatus includes a rigid, molded plastic frame having an upper surface 11 and a lower surface 12, with the upper surface having an elongated, generally rectangular opening 14 therein. As illustrated in the figures, the frame 10 preferably is formed of a base member 15 and top member 16 joined, such as by molding strip 17 to provide a generally rectangular enclosure. Preferably the top member 16 is formed with an elevated portion 18 at each end thereof, with the opening 14 extending between the elevated portions. A stationary, hollow, transparent cylinder 20 is longitudinally disposed within the frame, and is the contact surface against which the paper to be copied is placed. The cylinder rests on bosses 21, which may be formed as an integral part of the base member, and is supported above the lower surface 12 at least a distance sutficient to permit the paper to be copied, the copy paper and flexible pressure means to be wrapped around the cylinder. Preferably the bosses 21 are positioned at or near the end of the cylinder 20 so that the papers may be wrapped around the cylinder over substantially its entire length. The cylinder may rest directly on the bosses, or on a resilient cushioning material, such as sponge rubber, flexible foam, and the like, which is held in position by the bosses. As shown in the figures, the upper portion of the cylinder 20 preferably extends through the opening 14 in the upper surface of the frame. The upper portion of the cylinder is engaged by the top member 16 of the frame at each end of opening 14 so that the cylinder is fixedly held in position between the top member 16 and the bosses 21.

The cylinder 20 may be formed of any clear, transparent material which does not absorb an undue amount of ultraviolet radiation and which is not adversely affected by such radiation. Acrylic resins, such as polymethyl methacrylate resins available under the trademarks Lucite" and Plexiglas, which contain no ultraviolet inhibitors, have been found to be excellent materials for use in forming the cylinder.

A single tubular lamp 2 2, such as a fluorescent lamp, is mounted within the frame and extends concentrically through the cylinder 20 so that radiation from the lamp passes uniformly through the wall of the cylinder over the entire contact surface. In this manner the radiation emitted from the entire circumference of the lamp is directed toward the contact surface and used in the exposure. Lampholders or sockets 23 which are mounted on the frame, support the tubular lamp 22 along the horizontal axis of the cylinder 20. While other types of tubular lamps may be used, tubular fluorescent lamps preferably are used. Since the intensity of fluorescent lamps tends to fall off somewhat at the ends of the lamp, only that portion of the lamp which has a relatively uniform output is used to supply illumination in the copying process. As shown in FIG. 3, it is preferred that the transparent cylinder 20 extend over only that portion of the tubular lamp which is relatively uniform in output so that substantially uniform radiation will be transmitted over the entire area of the contact surface. Alternatively, the cylinder may extend over a greater length of the lamp, as long as only that part of the cylinder which extends over the part of the lamp having a relatively uniform output is used as the contact surface in making exposures. When it is desired to produce copies by the diazotype process, it is necessary to use as the tubular lamp, a lamp capable of emitting ultra-violet rays in the 3500 to 4200 Angstrom range.

The lampholders 23, which support the tubular lamp 22 and hold it securely in position, are mounted on the frame and secured thereto by any suitable means, such as by adhesives, mechanical fasteners, and the like. The lampholders 23 connect the lamp to a source of electric current, such as by wiring connecting the lamp cathodes or filaments in series with a ballast 24, which is mounted Within the frame on support 25. A conventional starter (not shown) and a timer-switch 26, which operates a line switch, control the flow of current to the lamp. A conventional extension cord may be used to connect the unit to an electrical outlet having the required voltage rating. The ballast 24 serves to limit the current to the lamp and supplies sufiicient voltage to start and operate the lamp. Any suitable conventional mechanical or electrical timerswitch may be used, such as, for example, a mechanical timer-switch of the wound spring type. Such a timer usually has a winding stem and a pair of normally open electrical contacts. Upon winding, the contacts are closed, thereby completing the circuit to the lamp, causing it to light. When the mechanism is unwound, the contacts open, shutting off the lamp current and causing the lamp to go out. The mechanism unwind-s at a predetermined rate, so that the length of time the lamp is on may be controlled. A series of scale markers is provided on the face of the timer-switch to indicate the length of time the lamp is to be on.

In order to hold the light sensitive copy paper tightly and in conformed relationship against the paper to be copied and around the cylindrical contact surface, a flexible plastic sheet 28 is disposed around the cylinder. The sheet 28, which preferably is opaque, is generally rectangular in shape, having a width substantially coextensive with the length of the contact surface and a length slightly greater than the circumference of the cylinder 18. The length of the sheet 28 is such that when the original paper and the copy paper are wrapped around the cylinder, the sheet applies a firm, even pressure against the papers holding them securely and in conformed relationship against the cylinder. The flexible pressure sheet 28 is relatively thin, that is usually less than about 10 to 15 mils thick, and is preferably formed of a tough plastic film which is resistant to ultarviolet radiation such as polyvinyl fluoride film, polypropylene film, polyester film,

polyethylene film, and the like. The flexible sheet may be provided with an opening 33 above the cylinder to provide a tell-tale or pilot lamp light to indicate when the lamp is on.

According to a preferred embodiment, as illustrated in the figures, one end 29 of the sheet is fixed to the frame along one edge of the opening 14. The other end 30 of the sheet is movable from a position on top of the fixed end 29, so that the sheet extends substantially completely around the circumference of the cylinder 20, to a position away from the cylinder, so that the upper portion of the cylinder is exposed. When the sheet is in the latter position, the original paper and copy paper are inserted between the cylinder and the flexible pressure sheet and wrapped around the cylinder. The movable end 30 of the sheet 28 is then positioned on top of the fixed end 29 so that the sheet applies a firm even pressure against the papers.

Suitable closure means are provided to keep the sheet securely in position when it is wrapped around the cylinder. Magnetic closure means have been found to be suitable for maintaining the flexible pressure sheet in this position. According to this embodiment, a first magnetic bar member 31 is secured to the fixed end 29 of the sheet, and a second magnetic bar member 32 is secured to the movable end 30 of the sheet. The two magnetic bar members are substantially coextensive in length over the width of the flexible sheet. Alternatively, one of the magnetic bar members may be replaced with a metallic bar member. Other suitable closure means, capable of holding the flexible sheet in position around the cylinder, may also be used. Similarly, pressure means other than the flexible sheet, such as spring clips, or other resilient, extensible means, which are capable of exerting a relatively uniform pressure over the length of the cylinder, may also be used.

Since the exposure apparatus of this invention is intended for use by persons having little skill or experience in making contact prints, it is generally preferred to provide the apparatus with photosensing means for determining the proper duration of exposure to be used in making prints. As noted above, this photosensing means may consist of either photoelectrical sensor system or a non-electrical light measuring system. The electrical sensor system is illustrated in FIGURE 2 and comprises the use of the apparatus described in copending patent application Ser. No. 603,452, filed Dec. 21, 1966. In this system, at least one, and preferably two or more, openings 35 are provided in a portion of the flexible sheet 28 that overlies the papers wrapped round the cylinder. A photoelectric cell 36 is mounted on support 25 behind each opening 35, so that light transmitted through the papers passes through the openings and impinges on the photoelectric cells. The photoelectric cells 36 are connected to a potentiometer 37 and a current indicating meter 38 to measure and register the amount of light impinging on the photocells. The meter 38 is provided with a scale calibrated in arbitrary time units so that a numerical value may be given to the meter reading. The units on the meter scale are calibrated with the scale markers on the face of the timer-switch 26, so that the reading from the meter may be transferred to the timer-switch to provide the proper duration of exposure.

Two embodiments of the non-electrical light measuring system for determining exposure time are illustrated in FIGURE 1; namely a filter-intensity system, as shown in the A portion of FIGURE 1, and a colorimetric comparison system, shown in the B portion of FIGURE 1. In the filter-intensity system, a plurality of light filters are provided in the flexible pressure sheet 28 above the upper portion of cylinder 20. Filters of different intensities are used, with the filters being arranged along the sheet so that a graduated scale of filter intensity is provided. Each filter in the scale is given a predetermined numerical value.

Thus, in making exposures of original papers by contact copying techniques, the amount of light passing through the original paper is the principal factor affecting the exposure time to be used in making copies. This value depends on the opacity of the paper, and may vary from paper to paper according to the thickness of the paper, its density, color, and the like. By providing a series of filters of varying intensity, a visual determination of the opacity of the original paper can be made by determining the first filter in the graduatedscale through which no light is transmitted when the light source is turned on. The timer-switch 26 is then merely turned to the same numerical value as that associated with the filter, to thereby set the proper exposure time.

The exposure apparatus must, of course, be calibrated, so that for any given filter used, the correct exposure time may be set on the timer. This calibration is done experimentally for each light filter in the system by determining the value at which light is first transmitted through the filter, and then determining the exposure time required for that value. This calibration procedure is then repeated using filters of different intensities until a wide range of filter intensities have been obtained.

In the colorimetric comparison system, shown in the B portion of FIGURE 1, a plurality of openings 43 is provided in the flexible pressure sheet 28, with each opening being surrounded by a colored background area 44. Each background area 44 surrounding an opening 43 consists of a different shade of the same color, with the background areas being arranged to provide a tonal gradation from the lightest shade to the darkest shade. The shades used are selected to provide a comparison with the shade of the paper to be copied. By providing a series of background areas of varying shades, a visual determination of the opacity of the original paper can be made, by comparing the shade of the original paper, as viewed through openings 43, with the shade of the background areas. Thus, the original paper is wrapped around the contact surface and covered by the flexible sheet. When the tubular lamp is turned on, a visual comparison is made of the shade of the original paper and the background areas. The timer is then set at the value associated with the background area which matches or most nearly matches the shade of the original paper. This provides a rapid, accurate determination of the proper exposure time.

It is also necessary to first calibrate the exposure apparatus so that for a given shade of background area, the correct exposure time may be set on the timer. Sufficient standard background areas are provided to cover a wide range of opacities. Preferably, the back side of the flexible sheet, opposite the background areas, is masked to facilitate matching of the shades. If desired, both the original paper and the light-sensitive copy paper may be wrapped around the contact surface when the exposure time determination is made. If this procedure is followed, however, the background areas must be shades which have been calibrated using the original paper and the copy paper.

The exposure apparatus of this invention may be used to make contact copies or prints of original papers, as by the diazotype process, in the following manner. The photosensitive surface of a diazo paper 40 is placed against the unprinted side of an original paper 41, and the papers, thus oriented, are inserted into the space between the cylinder 20 and the flexible sheet 28, when the movable end 30 of the sheet is moved to a position away from the cylinder, with the printed surface of the original paper 41 in contact with the surface of the cylinder. When the papers are wrapped around the cylinder, the flexible pressure sheet 28 is wrapped around the rest of the contact surface by placing the movable end 30 of the sheet on top of the fixed end 29, so that the sheet presses both papers into close mutual contact and holds them firmly against the cylinder. The magnetic bar members 31, 32

attached to the ends of the sheet maintain the sheet in position.

The timer-switch 26 is then turned, closing the contacts and causing the tubular fluorescent lamp to light. The amount of light transmitted through the papers and openings 35, and impinging on photocells 36 is measured and registered on meter 38. This value is then transferred to the timer-switch, which is set at the appropriate value, thereby providing the proper duration of exposure. Alternatively, the non-electrical light measuring systems described above may be used in determining the correct setting by the timer. The exposed copy paper may be processed by any conventional diazotype procedure.

Since the apparatus of the present invention is a relatively inexpensive exposure device particularly well suited for persons who may desire to make copies only infrequently, an adjunct of the apparatus, for making prints by the diazotype process, is a solution for developing the exposed print, the solution having shelf life so that it may be used over extended periods of time without deterioration. Such a preferred developing solution is disclosed in application Ser. No. 603,461, filed on Dec. 21, 1966. Thus the developing solution, containing a suitable azo coupler, is prepared and stored in hermetically sealed, light impervious containers from which it is discharged and applied to the exposed print to form the azo dye image, the solution preferably being applied to the exposed paper in the form of a spray.

The apparatus described hereinabove has been shown to be relatively simple in construction and operation since it has no complex or moving parts. However, it is capable of rapidly producing accurate legible copies of original papers.

The dimensions of the frame may be varied widely and are dependent in part on the length of the tubular lamp and the diameter of the cylinder. Preferably, the frame is of sufficient length so that the tubular lamp is completely enclosed within the frame, and is of sufficient height so that a portion of the cylinder extends through opening 14. While the diameter of the cylinder may vary, it is generally preferred that it is great enough so that conventional letter-sized paper may be Wrapped around the cylinder without the edges overlapping. But the diameter should not be so great as to require more than a relatively short period of exposure in making the prints. Cylinders having a diameter of between about 2 /2 inches and 3 /2 inches have been found to provide good results.

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations or adaptations of the invention.

I claim:

1. An apparatus for making direct contact prints which comprises a frame member, a stationary, transparent,

cylindrical contact surface, said contact surface extending over at least that portion of the light source which has a relatively uniform output so that subsequentially uniform radiation is provided over the contact surface, flexible pressure means extending substantially completely around the cylindrical contact surface, with a portion of said pressure means being removable from said contact surface to permit the insertion of an original paper and a sheet of light sensitive copy paper between said pressure means and the contact surface, said pressure means, when wrapped around the contact surface, holding said papers securely and in conformed relationship against said contact surface, closure means associated with said pressure means to maintain the pressure means around the contact surface, said flexible pressure means being of substantially opaque sheet material and having a plurality of light intensity comparison windows positioned to overlie said papers, light intensity grading means at each window arranged to provide a graduated scale, indicia at each window and timer means for controlling duration of exposure of said papers to light, said timer means including a switch dial having indicia thereon correlated to and calbrated with the indicia at said windows, whereby variations in required exposure time resulting from variations in the characteristics of the original paper can be determined and compensated for.

2. The apparatus defined in claim 1 wherein the light intensity grading means is a filter intensity system, said windows each including a light filter of different intensity, said filters being arranged to provide a graduated scale of filter intensity along the pressure means.

3. The apparatus defined in claim 1 wherein the light intensity grading means is a colorimetric comparison system in which each of said windows comprises an opening surrounded by a colored background area, each of said background areas being arranged to provide a tonal gradation from the lightest shade to the darkest shade.

References Cited UNITED STATES PATENTS 884,297 4/1908 Sabroe 77.5 2,380,244 7/1945 Jones 9510 2,572,930 10/1951 Heldens 9573 2,639,751 5/ 1953 Flaherty 292251.5 2,729,155 1/1956 Fix 95-1l.5 X 3,289,562 12/1966 Hicks 95-77.5

FOREIGN PATENTS 990,637 6/1951 France.

NORTON ANSHER, Primary Examiner. M. H. HAYES, Assistant Examiner.

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