US2220207A - Control device for a printing light - Google Patents

Description

NOV. 5, 1940. BUSSE CONTROL DEVICE FOR A PRINTING LIGHT Filed Dec. 7, 1937 In venf or Ferd/hand Busse By His Affornw/ Patented Nov. 5, 1940 UNITED STATES PATENT OFFICE Ferdinand Busse, Munich, Germany, assignor, by mesne assignments, to General Aniline & Film Corporation, New York, N. Y., a corporation Delaware Application December 7, 1937, Serial No. 178,480

4 Claims.

The present invention relates to a control device for a printing light.

One of its objects is to provide an improved control device for a printing light, such as is used in an enlarging apparatus and comprising means for changing the kind and intensity of the light which is used in examining and projecting the negative for enlargement.

Further objects of the invention will be ap-.

parent from the detailed description following hereinafter.

Reference is made to the accompanying drawing in which I Figure 1 illustrates the position of the support during the selection of the negative to be enlarged in accordance with the invention, a heat screen being arranged in the path of the printing light,

Figure 2 illustrates the position of the support during the exposure of the photographic material in accordance with the invention, a scattering disk being arranged in the path of light.

Photographic enlarging apparatus are operatedeither with direct or scattered light. For obtaining a direct light a projecting lamp consisting of clear or frosted glass is used as source of light. The light rays are collected by a condenser and thrown on to the negative. The enlarged images made with such an illuminating device are distinguished by sharp contours and gradations of hue and are generally used for scientific or technical works only. A scattered light, however, results in softer images and in a limited reproduction of the grain and the scratches of the negative. It would seem to be ,of advantage to employ normally a scattered light when enlarging. The great loss of light, however, which is caused by using scattering means is a decided disadvantage.

According to the invention the light rays from the source of light are changed in kind and intensity in such a way that during the exposure of the photographic paper a scattered ing a mercury switch on the support of they Germany December 7, 1936 scattering screen and of the heat screen. When the scattering screen is moved into the path of light, a resistance arranged in the circuit of the lamps is automatically by-passed by the mercury switch.

In Figures 1 and 2 the scattering disk 2 and the heat screen 3 are arranged on a support 5 rotatable on an axis 4. The support is placed between the lamp l and a condenser (not shown) and carries a curved tube 6 containing mercury. In the position of the support 5 shown in Figure 1 the circuit flows over a resistance 1 to the lamp I while in the position of the support shown in Figure 2 the resistance 1 is by-passed so that the lamp l receives a greater intensity of light. The support 5 is turned by a lever 8 and is so constructed that during the selection of the images to be enlarged the absorbing disk 3 is in the path of the printing light and during the exposure the scattering screen is in the light path.

What I claim is:

. 1. A control device for a printing light comprising, in combination, a light source, a sup port movably mounted adjacent the path of light from said source, a heat resisting screen and a light scattering screen on said support, and means for moving said support to selectively and alternatively bring said heat resisting screen and said light scattering screen into and out of the path of said light, and means on said support and actuated by the movement thereof to change the intensity of the light from said source in accordance with the screen moved into the light path.

2. A control device for a printing light comprising, in combination, a light source, a support pivotally mounted adjacent the path of light from said source, a heat resisting screen and a light scattering screen on said support, means for rocking said support on its pivot to selectively and alternatively bring said heat resisting screen and said light scattering screen into and out of the path of light from said source, and means on said support and actuated by the position thereof, for varying the intensity of light from said source in accordance with the screen moved into the light path.

3. A control device for a printing light comprising, in combination, a light source, a support pivotally mounted adjacent the path of light from said source, a heat resisting screen and a light scattering screen on said support, means for rocking said support on its pivot to selectively and'alternatively bring said heat resisting screen and said light scattering screen into and out of the path of light from said source, and means on said support and actuated by the position theroef, for varying the intensity of light from said source in accordance with the screen moved into the light path, said last named means comprising an electric switch and a resistance in the current supply of said light source. a

4. A control device for a printing light comprising, in combination, a light source, a support pivotally mounted adjacent the path of light from said source, a heat resisting screen and a light scattering screen on said support, means for rocking said support on its pivot -to selectively and alternatively bring said heat resisting screen and said light scattering screen into and out of the path of light from said source, and means on said support and actuated by the position thereof, .for varying the intensity of light from said source in accordance with the 5 bring the heat resisting screen into the light 10 path, the current will flow through said resistance and when the light scattering screen is brought into the light path, the current will be by-passed around said resistance.

I FERDINAND BUSSE.

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