US2585519A - Exposing apparatus for photographic contact printing - Google Patents

Description

1952 1.. P. F. VAN DER GRINTEN 2,585,519

EXPOSING APPARKTUS FOR PHOTOGRAPHIC CONTACT PRINTING Filed July 16, 1947 INVENTOR LODEWIdK PIETER FRANS VAN DER GRINTEN Y W QM V ATTORNEYS Patented Feb. 12, 1952 UNITED STATES OFFICE EXPOSING' APPARATUSFOR .PHOTOv GRAPHIC GONTA'CTIPRINTING Application July16, 1947, Serial No. 761,314

In the Netherlands July 17, 1946 2 Claims.

This invention relates to an exposing apparatus for photographic contact-printing wherein flexible sheet materials such as an original and a light-sensitive film or paper are exposedtolight inclose contact with each other. The apparatus involved is of the type equipped witha hollow cylinder of light-pervious material which .511!- rounds a light source,.and with a flexible applying sheet for applying and holding the sheet materials to be exposed against the surface of the cylinder.

In exposing apparatus of this type the cylinder generally consists of glass and the applyingsheet is made of cloth or the like. The materialto be exposed is usually rotated with the cylinder or pushed over its surface in the course of exposure, so that exposure talresrplace while the material is moving. In some cases it is desirable to expose the material while it is stationary; for example, when the originals to be. copied varyin t";

transparency or translucency and require difierent periods of exposure for proper treatment. vIn such cases an apparatus adapted for stationary exposure is the simplest to use. In. apparatus of that type the size of the material that can be exposed is limited according to the diameter of the cylinder, and this is important. because the diameter of the cylinder is subject topractical limitations. It is easier to obtain a flawless glass cylinder with a small diameter, and the cylinder must be flawless in the case of stationary exposure. Secondly, a cylinder of small diameter makes it possible to use a lamp of lower power, also one of smaller length, in, the case of tubular lamps, and this presents advantages with respect both to the cost of electric current and to the cooling of the lamp.

Inorder to have the size of the sheetmaterlal that can be exposed as largeasfeasible'itimust be'possible to use the largest feasiblepart. of the circumference of the cylinder for exposure. This becomes-possible if the flexible applying sheet is made movable onto and from the cylinder as the cylinder is rotated back and forth for the introduction and the removal, respectively, of the material to be exposed. To accomplish this, however, the applying sheet normally must be fastenedto the cylinder alonga generating line. of its surface, and that involves other difliculties. In such event a relative adjustment of the applying sheet and the cylinder-,e. g., in order to remove glass'flaws' from the field of exposure or to correct any slanting tendency of the applying sheet, is not possible. Also, the replacement of a glass cylinder broken or cracked during operation is a complicated matter.

According to the present invention, these dimculties-may be overcome by providing the applying sheet with a lengthening extension in the form'of'two drawing members located oneither side of the sheet beyond its breadth, such as spaced parallel cords, wires, tapes, belts, ribbons, ropes,- etc., and passing the interconnected applying sheet and extension about the cylinder in the form of a loop so that portions of the same cross each other and extend away from the cylinder in opposite directions with the applying sheet passingbetween the .two drawing members where they'cross.

This and other features of the present inven- 1 tion will be apparent from the followingdetailed description of an illustrative embodiment thereof and from the accompanying illustrative drawing which forms a part hereof, and in which:

Fig. 1 is a vertical-cross section of anexposing apparatus embodying the invention;

Fig. 2 is a diagrammatic representation of the manner of'arranging the applying sheet and its drawing members about the cylinder; and

Fig. 3 is a fragmentary plan view showing details. of one manner of connecting the applying sheetwith the drawing members.

As seen in Figs. 1 and 2, a glass cylinder I that is to be used for exposure is arranged horizontallyso as to be'rotatable about its axis. The cylinder'is ,made rotatable by having its surface rest on upper portions of horizontally spaced series of rotary discs 3 and 4 and which are carried on spaced horizontal shafts or rods 3a and 411, respectively. These shafts or rods are mounted in the frame 20. Located inside and on the axis of cylinder! is a tubular lamp 2, which is slightly longer than the cylinder. A flexible applying cloth is designated 5 and possesses a length at least rsufiicient to encircle the cylinder l. ends of this cloth are provided with transverse rods. '6 and 1 (Fig. 1), which. extend through terminal hems 5a and 512, respectively, of the cloth so thatthe ends of the rods project beyond the .breadthofthe' cloth on either side thereof as seen,..for example. at Baand 6b in Fig. 3.

The projecting ends of the rods 6 and l are interconnected by spaced, parallel flexible drawing members a and 9, which may be ribbons. cords, or'the like as mentioned above. Thus the applying sheet 5 and the drawing members 8 and 9 together .form an-endless belt member. As may be seen particularly from Fig. 2, this endless belt member is passed or wrapped about the glass cylinder in the form of a loop thereon, and where the belt portions extending from the loop across each other to leave the cylinder, 1. e., where The with its surface.

the sheet 5 itself moves to and from the surface of the cylinder, the body of the sheet 5 lies and may pass freely in the space between the two drawing members 8 and 9. Thus the applying sheet 5 is rendered capable of being passed or wound onto the cylinder I so far that it will cover the full 360 of the surface of the cylinder; which is to say that the glass cylinder can now perform one complete revolution and can accommodate sheet material to be exposed, between itself and the sheet 5, over the full sweep of its circumference. A complete utilization of the surface of the glass cylinder is therefore made possible.

As shown in Fig. 1, the portions of the applying sheet 5 and the drawing members 3 and 9 that extend oppositely away from the cylinder I lead from it over spaced horizontal pulleys or rollers i0 and ll below the cylinder, and thence together again beneath these rollers in endless belt arrangement. One of the rollers, as at H2, i held in the frame 28 below and toward the back of cylinder I, while the other roller H which receives the sheet 5 is held between forward extensions 20a of the frame at the front of the apparatus. The length of the endless belt member and the forward spacing of the front roller II are such that the portion of sheet 5 extending between cylinder I and roller ll constitutes a table surface at l2 ahead of the cylinder. A fixed guiding plate l3 presents a flat surface just below the applying sheet at l2, to support the applying sheet there so that an original and a light-sensitive sheet to be exposed may be easily placed on it for movement by it into contact with the exposing cylinder.

In order to keep the requisite tension in the endless belt member, the drawing members 8 and 9 may each be made with an elastic portion such as a tension spring [4. The frame 20 is provided with a covering hood 2! for complete enclosure of the exposing cylinder. Hood H is hinged to the frame at 22 and has a handle 23 to facilitate opening the hood.

When a photo copy is to be made, the original to be copied is placed on the surface of the applying sheet 5 at l2, together with the lightsensitive sheet material to be exposed. Then the applying sheet is pushed into the apparatus in the direction of arrow l5, the glass cylinder 5 thus being rotated until the materials have been moved or wound completely thereupon in contact These materials may possess any width accommodated by the axial length of the cylinder and any length up to a maximum equalling the outside circumference of the cylinder. The materials thus applied to the surface of the cylinder are held there by the applying sheet and exposed to the light transmitted through the glass cylinder from the tubular lamp. After due exposure the applying sheet 5 is moved back in the direction of arrow [6, the glass cylinder thus also being turned back so that the sheet materials arrive again at the table location [2 where they may be removed for replacement by another set of materials to be exposed.

A stripper I has an edge held next to the surface of the cylinder l above plate [3, in position to strip on any material that may tend to stick to the cylinder as it is turned back for the removal of materials after an exposure. The

stripper I1 is made impervious to the light from lamp 2, and it is so disposed between the lamp and the table surface at I2 that it acts not only as a stripper but also as a light screen to keep the effective light from falling on sensitive material at I2.

I claim:

1. An apparatus for exposing flexible sheet materials in photographic contact printing, comprising a hollow rotatable cylinder of lightpervious material, a light source within the cylinder and a flexible sheet for applying said sheet materials to the surface of the cylinder for exposure, said flexible applying sheet being of a length suflicient to substantially encircle the cylinder and having connected with at least one of its ends a lengthening extension in the form of spaced flexible drawin members located on either side of the body of the sheet, the interconnected sheet and extension passing about the cylinder as a loop thereon from which portions of said sheet and extension, respectively, extend in opposite directions so that they cross each other adjacent the cylinder with the sheet passing between the spaced drawing member, said drawing members being connected with both ends of said sheet so that the sheet and the drawing members together constitute an endless belt.

2. An apparatus for exposing flexible sheet materials in photographic contact printing, comprising a light-pervious cylinder rotatable about a horizontal axis, a light source within the cylinder on its axis, spaced horizontal rollers below and parallel to the axis of the cylinder, one roller back of the cylinder and another spaced in front thereof, a flexible applying sheet of a length sufficient to substantially encircle the cylinder and having a lengthening extension connected with the ends of the sheet to form therewith an endless belt member, said extension comprising spaced flexible drawing members located on either side of the body of the sheet, said belt member passing about the cylinder as a loop thereon from which portions of the sheet and the drawing members, respectively, extended in opposite directions in crossed relationship at the lower side of the cylinder with the sheet passing forward through space between the drawing members, the extending portions of said sheet and said drawing members leading to and over said front and said back rollers, respectively, and then together beneath said rollers, the sheet portion extending between the cylinder and said front roller constituting a table surface for receiving sheet materials to be applied to and exposed on the cylinder, said drawing members comprising elastic portions holding the belt member on the cylinder and the rollers under tension.

LODEWIJK PIETER FRANS VAN DER GRINTEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 704,232 Bell July 8, 1902 789,773 Wagenhorst May 16, 1905

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