US2346988A - Photographic printing apparatus - Google Patents

Description

April 18, 1944. E. B NOEL IHOTCC-HATU.C PRINTING APPARATUS Filed March 18, 1941 Inventor: I Edw rd B. Noet,

His Affor'neg.

Patented Apr. 18, 1944 I 2.34am rno'roanarnlc ramrmo APPARATUS Edward 3. Noel, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation. of

New York Application March 18, 1941; SerialNo. 383,975 (Cl. 95-73) 9 Claims.

The recent development of photographic print ing papers in which the effects of either soft or hard papers are obtained from a single emulsion by varying the color content of the light used for exposure (Photo Technique, October, 1940, p. 59- v Rowland S. Potter) has given rise to a need for a light source in which the relative percentages of the various color components may be varied at will and pre-set at any predetermined desired values before the exposure is made. It is an object of the present invention to provide a printing apparatus incorporating a source of light, the color composition of which may be conveniently and readily varied in the aforesaid manner. Further and other objects and advantages of the invention will be apparent from the following detailed description and from the accompanying drawing in which like numerals indicate like parts throughout and in which Fig. 1 represents apparatus embodying the principles of the invention, while the Fig. 2 represents an alternative modifi cation of the arrangement shown in Fig. 1.

Referring to Fig. 1, the apparatus there shown comprises generally of at least one lamp l concentrically surrounded by a rotatable, cylindrical filter II which is composed of a pair of semicylindrical sections l2 and 13 of different colors. For example, the semi-cylindrical section l2 may be minus blue (a type of yellow filter) and the section 13 minus red (9. type of blue filter). After passing through the filter, the light from the lamps l0 goes through the ground glass diffusing plate H which renders the illumination on the photographic printing plate or negative l5 uniform. By rotating the cylinders I l to any de- ,sired angular position, the color of the light which passes through the ground glass to the plate l5 may be given any relative percentage composition of the light from sections l2 and I3 varying all the way from 100% minus red when the filter I3 is in the downward position, to 100% minus blue when the filter [2 is in that position. The lamps It may consist of any of the sources of "white, or

daylight illumination which are available inthe Alternatively, the lamps may comprise a clear glass tube in which a gaseous discharge capable of emitting radiation which excites a fluorescent material is operated. In that-case, the sections l2 and I3 may comprisesemi-cylindrical glass walls upon which fiuoresjcentmaterials capable of emitting the corresponding colors may be coated. I

For the purpose of rotatin' the members H to the desired positions, a gear system indicated generally by the numeral limay' beprovided. The gear system may comprise *a series "of driving gears I! which cooperate with. the sprockets l8 positioned on the ends'of the members H, a set of idler gears I! being provided so that the motion of each of the drivinggears is in the same direction. The filter members II will rotate in the trough formed between the'driving gears. The whole system may be rotated by a suitable knob 20 provided on the shaftof the left-hand driving gear H, the scale 2| being provided for the purpose of calibrating the rotation of the filter members in terms of the color composition of the light reaching the photographic plate. The various members of the system may be supported by any suitable means. For example, the lamps ID are supported by the bracket 22 and the sockets 23 appended thereto, while the gears l1 and is are supported by the bracket indicated generally by the numeral 24. The lamps l0 may be energized by any suitable source of electric power (not shown).

Referring now to the alternative modification shown in Fig. 2, the lamp III in this case is housed within a reflector 25 which may be parabolic in form or of any form which will direct the rays of the lamp I0 toward the diifusing plate i4 andthe photographic plate IS. The filter members may take the form of the series of interlocking orthogonal vanes 26 and 21, the vanes 26 being of one color such as minus blue, and the vanes 21 of a second color such as minus red. For. the purpose of rotating the vanes 26 and 21, a gear system Ilia similar to that of Fig. 1 maybe proart, or any polyehromatic source capable of emitting at least the colors'which pass through'the filter. For example, they may take the form of an incandescent lamp or a fluorescent gaseous discharge tube of the type shown in the U. 8.

Patent 2,182,732 to Meyer, et al. The discharge tube in the latter case may be coated with a fluorescent material which produces polychromatic light having the desired colors as components.

vided. Similarly, the knob 20 and the dial 2| may be provided forthe purpose of setting the rotation of the vanes and for calibrating the rotation thereof. The operation of the vane system will be generally similar to that of Fig. 1. When the system is rotated to the position shown in the figure. only the minus red'vanes' 21 will be interposed in the path of the light from the lamp Ill, whereas when the system is rotated through approximately 90, only the minus blue vanes 26 will be interposed in that path. Different percentage compositions of the'colors minus blue and minus red may be obtained by rotating the systex'n to thecorresponding angular position between these two limits. It will be understood, of course, that the filter 26 may be replaced by a suitably supported layer fluorescent material which emits minus blue, while the fllter 21 may be similarly replaced by fluorescent material which emits minus red. In this case, the lamp it will, of course, take the form of a clear glass discharge tube which emits light capable of exciting the fluorescent material on the vanes.

It will be understood that many modifications o1 theafore-described system will occur to those skilled in the art to which it appertains. For example, the color filter may comprise more than two colors and the fllter members II and the vanes 28 and 21 broken into a corresponding number of sections to provide the additional colors. Father, many modifications of the gearing system and the supports may be used. It will also be understood that the described apparatus may be used for either contact printing or for enlarging apparatus. In the latter case, suitable light condensing means may be provided. All such modifications I aim to include within the scope of the appended claims.

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

1. In an apparatus for controlling the color composition of photographic printing light, a source of radiation capable of exciting fluorescent materials, fluorescent means for converting said radiation into either one of at least two separate colors and means associated with said firstmentioned means for causing it to project in a given direction light of only one or the other or said colors or for mixing said primary colors in varying proportions.

2; In an apparatus for controlling the color composition of photographic printing light, a tubular source of radiation capable of exciting fluorescent materials, rotatable tubular members having at least two longitudinally extending sections with fluorescent materials thereon capable of emitting difl'erent colors when excitedJiy said radiation surrounding said source, means for rotating said members whereby the relative amounts of said colors in the light output at a predetermined surface in the field of said source may be varied.

3. In an apparatus for controlling the color composition of photographic printing light, a source of radiation capable of exciting fluorescent materials, rotatable members having at least two sections with fluorescent materials thereon capable of emitting different colors when excited by said radiation surrounding said source, means for rotating said members whereby the relative amounts of said colors in the light output at a predetermined surface in the field 01' said source maybe varied from light of either color alone to any desired combination of the two colors, and difiusing means interposed between said rotatable members and said surface whereby the lilumination at said surface is rendered uniform.

4. In an apparatus for controlling the color composition of (photographic printing light, a photographic plate, a tubular source of radiation capable of exciting fluorescent materials, a rotatable, cylindrical member having longitudinally disposed sections coated with fluorescent materials capable of fluorescing with different colors concentrically surrounding said source and interposed between said source and said plate, diflusing means between said member and said plate, and means for rotating said member whereby the relativ amounts of said colors in the illumination at said diiiusing surface may be varied from light of either color alone to any desired combination of the two colors.

5. man apparatus for controlling the color composition of photographic printing light, a source of polychromatic light, a plurality of illters comprising interlocking rotatable vanes oi at least two colors interposed in the path of the rays from said source, means for rotating said vanes whereby the relative amounts of said colors in the light at a predetermined surface in the fleld of said source may be varied from light of either color alone to any desired combination of the two colors.

6. In a'n"apparatus for controlling the color composition of photographic printing light, a photographic plate, a tubular source of polychromatic light, reflector means for directing radiation from said source in the direction oi said plate, a plurality of filters comprising interlocking rotatable vanes or at least two colors interposed in the path otsaid rays, and means for rotating said vanes whereby the relative amounts of said colors in the light impinging upon said photographic plate may be varied from light of either color alone to any desired combination of the two colors.

7. In an apparatus for controlling the color composition of photographic printing light, a photographic plate, a source of radiation capable of exciting fluorescent materials, reflector means" for directing the radiation from said source in the direction of said plate, a plurality of interlocking rotatable vanes coated with fluorescent materials capable of emitting different colors interposed in the path of said rays, and means for rotating said vanes whereby the relative amounts of said colors in the light impinging upon said photographic plate may be varied from light of either color alone to any desired combination of thetwo colors.

8. In an apparatus for controlling the color composition of photographic printing light, a photographic plate, a tubular source 01 polychromatic light, reflector means for directing radiation from said source in the direction of saidplate, a plurality of filters comprising interlocking rotatable vanes 01 at least two colors interposed in the path of said rays, and means for rotating said vanes whereby the relative amounts of said colors in the light impinging upon said photographic plate may be varied from light of either color alone to any desired combination of the two colors, and difiusing means for rendering the illumination on said plate uniform interposed between said vanes and said plate.

9. In an apparatus for controlling the color composition of photographic printing light, a photographic plate, a source of radiation capable of exciting fluorescent materials, reflector means for directing the radiation from said source in the direction of said plate, a plurality of interlocking rotatable vanes having fluorescent materials capable of emitting diii'erent colors interposed in the path of said rays, and means for rotating said vanes amounts of said colors in the light impinging upon said photographic plate may be varied from light of either color alone to any desired combination of the two colors, and diffusing means for rendering the illumination interposed between said plate and said vanes.

EDWARD B. NOEL.

whereby the relativeon said plate uniform

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