US3734614A - Photographic copying apparatus - Google Patents

Abstract

A photographic copying apparatus wherein the light source is an elongated electronic flash lamp and the reflector is a hollow pyramid which surrounds the lamp and diverges in a direction toward the support for copying material. The symmetry axis of the reflector coincides with the axis of the lamp. A polygonal light mixing duct is installed between the support for copying material and the open base of the reflector, and that end of the duct which is remote from the reflector contains a pane of light diffusing material. The walls of the reflector are cold light mirrors which transmit heat. One or more guides for color filters are installed between the base of the reflector and the adjacent end of the mixing duct. Such end of the mixing duct registers at least with the major part of the base.

Description

[111 3,734,614 51 May 22,1973

[S4] PHOTOGRAPHIC COPYING APPARATUS [75] Inventor: Wolfgang Zahn, Munich, Germany [73] Assignee: Agfa-Gevaert Aktiengesellschatt,

Leverkusen, Germany 22 Filed: June7, 1971 21 Appl.No.: 150,435

[30] Foreign Application Priority Data Brendel ..355/67 X Clark ..240/106 X Primary Examiner-Samuel S. Matthews Assistant Examiner-Michael L. Gellner Attorney-Michael S. Striker [57] ABSTRACT A photographic copying apparatus wherein the light source is an elongated electronic flash lamp and the reflector is a hollow pyramid which surrounds the lamp and diverges in a direction toward the support for copying material. The symmetry axis of the reflector coincides with the axis of the lamp. A polygonal light mixing duct is installed between the support for copying material and the open base of the reflector, and that end of the duct which is remote from the reflector contains a pane of light diffusing material. The walls of the reflector are cold light mirrors which transmit heat. One or more guides for color filters are installed between the base of the reflector and the adjacent end of the mixing duct. Such end of the mixing duct registers at least with the major part of the base.

8 Claims, 2 Drawing Figures PATENTEUHAYZZ I973 INVENTOR WOLFGANG ZAHN 0x40! $"Lr 1 PHOTOGRAPHIC COPYING APPARATUS BACKGROUND OF THE INVENTION The present invention relates to photographic copying apparatus in general, and more particularly to improvements in those components of photographic copying apparatus which are used to generate and direct light against copying material.

It is already known to employ in a photographic copying apparatus a lamp house which contains an incandescent-lamp with a thread-like filament located in the symmetry axis of the reflector. The reflector is a hollow cone which presents serious problems, especially as concerns the withdrawal of heat. Thus, a conical reflector cannot be assembled of cold light mirrors. Furthermore, since the filament is located in the symmetry axis of the hollow conical reflector, all of the energy which is radiated from the lamp and is reflected on any portion of the internal surface of the conical reflector is caused to pass through the region of the filament and toward the portion which is located diametrically opposite the light reflecting portion. This brings about extremely high concentration of energy in the region of the filament so that the latter is destroyed after relatively short periods of use.

It was also attempted to employ in photographic copying apparatus light sources in the form of electronic flash lamps. Such lamps are desirable when it is necessary to produce high concentrations of light. An important advantage of electronic flash lamps is that their light output is very high and thattheir heat radiation is relatively low. The attemptsto use electronic flash lamps failed mainly because the dimensions of such lamps are rather large-so that they were not considered satisfactory for illumination of relatively small prints.

SUMMARY OF THE INVENTION An object of the invention is to provide a photographic copying apparatus with novel and improved means for generating, mixing and confining copying light.

Another object of the invention is to provide a photographic printing apparatus with a lighting arrangement whose light output is high, whose dimensions are relatively small, and which can insure uniform illumination of copying material.

A further object of the invention is to provide a lighting arrangement which is constructed and assembled in such a way that it can automatically dissipate substantial amounts of heat.

An additional object of the invention is to provide a photographic copying apparatus with a novel light source and with a novel reflector for the light source.

The invention is embodied in a photographic copying apparatus which comprises a support for photosensitive copying material, an elongated rod-like electronic flash lamp which constitutes the light source and has a first end nearer to and a second end remote from the support for copying material, and a reflector surrounding the-lamp and diverging ina direction from the second toward the first end of the lamp. The symmetry axis of the reflector (which is preferably a hollow three-, fouror more-sided pyramid) preferably coincides with the longitudinal axis of the lamp. The height of the reflector preferably equals or approximates the length of the lamp, and the reflector preferably consists of partly transmitting mirrors, especially cold light mirrors which transmit substantial amounts of heat.

A hollow preferably polygonal light mixing duct can be installed between the open base of the reflector and the support for copying material. That end of the duct which is adjacent to the support preferably contains a plate of light-diffusing material and its other end is placed into substantial or full registry with the open base of the reflector. One or more guides for color filters may be provided between the duct and the open base of the reflector.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved copying apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary schematic sectional view of the light generating, mixing and confining components of a photographic copying apparatus which embodies the invention; and

FIG. 2 is an end elevational view of the light source and reflector as seen in the direction of arrows from the line 11- of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, there is shown a portion of a photographic copying apparatus which comprises a hollow pyramidal reflector 1 having fourtriangular walls 1a each of which consists of partly heat transmitting material. In accordance with a preferred embodiment of the invention, the walls la constitute cold light mirrors which can transmit substantial amounts of heat. The light is generated by an elongated rod-like source 2 which is an electronic flash lamp having a longitudinal axis which coincides with the symmetry axis of the reflector 1 (see FIG. 2). The terminals of thelamp 2 are indicated but not specifically referenced in FIG. 1. The energy source for thelamp 2 is shown at 102. It will be noted that the height of the pyramidal reflector 1 slightly exceeds the length of thelamp 2; however, it is equally possible to make the reflector 1 shorter so that its height actually equals or approximates the length of thelamp 2.

The area of the open upper end portion (as viewed in FIG. 1) or base lb of the reflector 1 preferably equals or approximates the area of the photosensitive printing or copying material 3 which is to be exposed to light furnished by thelamp 2. The printing material 3 is adjacent to a support here shown as a negative mask 4.

The exact manner in which the mask 4 or another suitable support is mounted in or on the housing of the photographic copying apparatus forms no part of the present invention. It suffices to say that one end of thelamp 2 is nearer to and that the other end of the lamp is more distant from the mask 4, and that the reflector l diverges in a direction from the other toward the one end of thelamp 2.

In accordance with an additional feature of the invention, the copying apparatus further comprises a polygonallight mixing duct 5 which is disposed between thebase 1b of the reflector 1 and the mask 4. The internal surface of theduct 5 reflect light and the light which issues from the upper end of the duct 5 (as viewed in FIG. 1) must pass through a light diffusing plate 6 of opal glass or the like. The purpose of theduct 5 is to insure intensive mixing of light which enters its open lower end and to thus guarantee that the material 3 is exposed to homogeneous printing light. The axial length or height of theduct 5 preferably exceeds its maximum transverse dimension; most preferably, the axial length of theduct 5 is at least twice its maximum transverse dimension. The cross-sectional area of theduct 5 preferably approximates or equals the area of the material 3, i.e., the area of that part of the material 3 which is to be exposed to printing or copying light. In accordance with still another feature of the invention, the copying apparatus comprises one ormore guides 107 for one ormore color filters 7 which can be introduced into the space between the base lb of the reflector 1 and the adjacent lower open end of themixing duct 5. The filter orfilters 7 may constitute subtractive color filters which are moved across the path of light issuing from thebase 1b to terminate the exposure of printing material to light in the respective color or colors, or they may constitute a means for coloring the light which issues from the base lb and is to impinge upon the printing material. If the illustrated filters are a substractive color filters, they serve as a means for blocking the transmission of light of a particular color to thus terminate the exposure of printing material to such light. If the illustratedfilters 7 are light coloring filters, they may be introduced across the path of light which passes into themixing duct 5 in such a way that they intercept some or all of the light which issues from the base lb of the reflector 1. The non-uniform coloration of light which passes through a coloring filter and enters theduct 5 disappears not later than when the light passes through the opal glass plate 6.

The operation of the copying apparatus will be readily understoodupon perusal of the preceding description. As shown in FIGS. 1 and 2, the light beams which issue from any selected point of thelamp 2 are either reflected on the internal surfaces of the reflector l or enter directly into themixing duct 5. For example, thepoint 2a of thelamp 2 emits light beams each of which is caused to enter the lower end of themixing duct 5, either directly or upon reflection on the internal surfaces of thewalls 1a. This holds true for thelight beam 2b which enters theduct 5 without reflection, for thelight beam 20 which is reflected only once prior to entry into theduct 5 and for thelight beam 2d which is reflected several times prior to entry into the duct.

The majority of light beams which enter the lower end of theduct 5 are inclined with reference to the axis of thelamp 2 so that such light beams are reflected again on the internal surfaces of the duct. Thus, the opening angle of beams which leave the reflector l by way of the open base lb is normally less than 180. Therefore, the improved apparatus exerts at least some directional effect upon the light which enters the mixing duct. The latter insures further homogenization of light which is homogenized again during passage through the opal glass plate 6 to insure soft and uniform illumination of printing material.

It was found that the space requirements of the just described illuminating arrangement are surprisingly low.

The reflector 1 may be assembled of three, four or more cold light mirrors to form a three-, fouror moresided hollow pyramid, and its open base is preferably in at least substantial but most preferably in full registry with the open lower end of themixing duct 5.

An important advantage of the improved copying apparatus is that the heat emission ofelectronic flash lamp 2 is relatively low. Therefore, the apparatus is not overheated even if the pyramidal reflector l is replaced with a conical reflector diverging in a direction from that end of the lamp which is remote from the support for printing material toward the support. However, a pyramidal reflector is preferred at this time because the light which is reflected on its internal surface does not have to pass across thelamp 2 but can be reflected around the lamp (see FIG. 2) prior to reaching theopen base 1b to enter the adjacent open end of the mixingduct 5.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. In a photographic copying apparatus, a combination comprising a support for copying material; an elongated rod-like electronic flash lamp having a first end nearer to and a second end remote from said support; a hollow pyramidal reflector surrounding said lamp and diverging in a direction from said second toward said first end, said reflector having an axis of symmetry coinciding with the axis of said lamp; and a light mixing duct interposed between said reflector and said support to mix at least some of the light which issues from said lamp and at least some of the light which is reflected by said reflector before such light reaches the copying material.

2. A combination as defined in claim 1, wherein the height of said pyramid at least approximates the length of said lamp.

3. A combination as defined in claim 1, wherein said reflector consists of at least three partly heat transmitting mirrors.

4. A combination as defined in claim 3, wherein said mirrors are cold light mirrors.

5. A combination as defined in claim 1, wherein said duct has a first open end facing said support and a second open end facing said reflector, said reflector having an open end adjacent to the second open end of said duct and further comprising light dispersing means extending across the first open end of said duct.

6. A combination as defined in claim 1, wherein said duct is provided with light-reflecting internal surfaces and has an end adjacent to said support, the crosssectional area of said end of said duct at least approximating the area of copying material at said support.

7. A combination as defined in claim 1, wherein said reflector has an open end in the region of said first end of said lamp and said duct has an open end adjacent to and said duct and at least one filter movable with referand at least substantially registering with the open end of said reflector.

8. A combination as defined in claim 1, further comprising guide means disposed between saidreflector 5 ence to said guide means across the path of at least some light which enters said duct.

Claims (8)

1. In a photographic copying apparatus, a combination comprising a support for copying material; an elongated rod-like electronic flash lamp having a first end nearer to and a second end remote from said support; a hollow pyramidal reflector surrounding said lamp and diverging in a direction from said second toward said first end, said reflector having an axis of symmetry coinciding with the axis of said lamp; and a light mixing duct interposed between said reflector and said support to mix at least some of the light which issues from said lamp and at least some of the light which is reflected by said reflector before such light reaches the copying material.

2. A combination as defined in claim 1, wherein the height of said pyramid at least approximates the length of said lamp.

3. A combination as defined in claim 1, wherein said reflector consists of at least three partly heat transmitting mirrors.

4. A combination as defined in claim 3, wherein said mirrors are cold light mirrors.

5. A combination as defined in claim 1, wherein said duct has a first open end facing said support and a second open end facing said reflector, said reflector having an open end adjacent to the second open end of said duct and further comprising light dispersing means extending across the first open end of said duct.

6. A combination as defined in claim 1, wherein said duct is provided with light-reflecting internal surfaces and has an end adjacent to said support, the cross-sectional area of said end of said duct at least approximating the area of copying material at said support.

7. A combination as defined in claim 1, wherein said reflector has an open end in the region of said first end of said lamp and said duct has an open end adjacent to and at least substantially registering with the open end of said reflector.

8. A combination as defined in claim 1, further comprising guide means disposed between said reflector and said duct and at least one filter movable with reference to said guide means across the path of at least some light which enters said duct.

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