US2303942A - Photographic process - Google Patents

Description

FLUORESCENCE OF Dec. 1, 1942. 'G. T. LANE EIAL 2,303,942

' PHOTOGRAPHIC PROCESS Filed Aug. 22, 1941 Fu l.

ALUMINUM FLUORESCENT ALUMINUM EMULSION SENSITIVE TO MATERIAL 11 GERDLILD T. LANE CLARENCE L.A.WYND

' INVENTORS BY MXQWCZZ A TTORNE YS Patented Dec. 1, 1942 PHOTOGRAPHIC PROCESS Gerould '1. Lane and ClarenceL. A. Wynd, Rochester, N. Y., assignors to Eastman Kodak Com- D y, Jersey Rochester, N. Y., a corporation of New Application August 22, 1941, Serial No. 407,959

2Claims.

This invention relates to the reproduction of engineering drawings and the like and particularly to a method for reproducing exactly a drawing layout, or design prepared or made on a rigid opaque support.

For many purposes it is desirable to have a. drawing made on an aluminum sheet or other rigid support which can be depended upon to hold dimensions exactly and which is not unduly fragile. It is also highly desirable to be able to make accurate copies of such drawings on work or template material such as aluminum sheets, plywood and the like.

In many manufacturing industries and especially in the production of aircraft and automobiles, full size layout drawings are made which after approval are transferred to template or work material such as sheet metal, wood or fabric. This transfer was formerly made by hand and often required up to sixty days to make dimensioned copies for a single automobile model.

Transfer by hand is not only time consuming but obviously subject to error. It has been proposed to obtain transfer by photographic copying which requires considerable space, good lenses and accurate adjustment for correct magnification. Inasmuch as several factors in photographic copying depend upon the operator it is clear that the copy is not necessarily an accurate one.

In accordance with the present invention this transfer or reproduction is made by contact printing so that an exact copy necessarily results from the practice of the invention and the question of tolerances does not arise. This is made possible by creating on an X-ray permeable opaque support such as aluminum or wood a drawing or sketch in terms of luminescent and non-luminescent areas. This drawing when placed in contact with a photographic layer carried on a suitable support will expose the layer so that when it is processed an exact copy of the drawing will be produced. The support for this layer is preferably the work or template material desired for use.

In accordance with the preferred form of the invention, the drawing is made on an aluminum sheet coated with a suitable material such as calcium tungstate lacquer which is rendered fluorescent and phosphorescent when excited by X-rays. This drawing is then placed in contact with a sensitized sheet and exposed to epipolizing radiation such as X-rays to which the drawing slightly expose the whole of the sensitive layer the added exposure brought about by the luminescence of the calcium tungstate provides sufllcient contrast for clean reproduction of line drawings. This effect may be increased by-adjusting the properties of the photographic emulsion, particularly by choosing an emulsion with a very high gamma or usingsuitable reducing formulas, so that the print has clean, black lines and no objectionable overall density.

In the drawing Fig. 1 is a, view in perspective of the drawing to be reproduced and Fig. 2 shows the drawing being contact printed on a sensitive layer.

As shown in Fig. 1 an X-ray permeable support H! such as aluminum is provided with a drawing or sketch l I made with an epipolic material such as calcium tungstate.

For reproducing the drawing l I it is placed in contact with a layer [2 sensitive to the luminescence of the calcium tungstate when activated with X-rays. X-ray radiation from a suitable source I3 is then directed through the aluminum sheet l0 to give the layer l2 an epipolized exposur corresponding to the outline defined by the calcium tungstate which continues to phosphoresce for some time after exposure. When processed the exposed layer [2 which is carried by a support l4 provides a work or template sheet.

Instead of drawing with a fluorescent pencilv or ink, it is prefered to coat the support III with a layer of fluorescent material and draw on this surface with a material opaque to the light the material fluoresces. The printing operation which is identical with the one described above exposes the photographic layer wherever the lines of the drawing do not shield the layer from the fluorescent light.

It is of course highly desirable that the drawing be in intimate contact with the photographic layer during the exposure. This may be accomplished in any desired way and a vacuum frame has been found to be well suited for this purpose.

It will be evident the process of the present invention not only eliminates the immense amount of work involved when copies are made by redrafting but also eliminates the possibility of errors in dimensions or in the omission of parts.

When it is remembered that, in the art to which the present invention is particularly applicable, the sheets upon which the drawings are made and reproduced range in size up to six sheet is permeable. Although the X-rays will feet Wide y twenty feet 8. the Practical difllgraphic technique will be appreciated.

Practice of the invention is, or course. not limited to th reproduction of engineering drawing and will be found useful in many instances where accurate reproduction is required, such as large maps. and where use 01' glass plates of the required size would introduce hazards to the safety of the operators.

Since those familiar with X-ray photography are well aware oi the many emulsions available and suitable for being exposed by the light emitted by the different fluorescent materials which may b employed for preparing the drawing to be reproduced, it is believed to be unnecessary to describe in this application the various possibilities. However, it may be mentioned that the matte transfer film described and claimed in application Serial No. 397,093 filed June 7, 1941, by Gerould T. Lane is admirably suited to receiving the exposure when calcium tungstate is the fluorescent material used in the process.

What w claim as new and desire to secure by Letters Patent of the United States is: v

1. The method of obtaining engineering drawings on opaque template material which com- 2,303,942 culties involved in employing ordinary photo-- prises preparing the drawing on a rigid Z-ray permeable support in terms of fluorescent and non-fluorescent areas, providing the opaque template material with a pho aphic layer sensitive to the fluorescence oi the material defining the drawing. placing said drawing'in contact with said sensitive layer, directing x-rays through said support, and developing the exposed layer.

2. The method of reproducing'drawings and the like which comprises forming on a rigid. opaque, non-frangible sheet coated with a layer which is rendered fluorescent and phosphorescent when activated by X-rays, a design which is opaque to the light emitted by said layer. exposing said sheet to x-rays whereby said layer is activated, holding said sheet while luminescent from such activation in contact with a sheet 0! opaque template material carrying a layer which is photographically sensitive to the luminescent light thus emitted, whereby the luminescent light impresses a latent image in said sensitive layer except where such light is intercepted by said design, and developing a visible image insaid sensitive layer.

GEROULD T. LANE. CLARENCE L. A. WYND.

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