Hoechst Aktiengesellschaft

Herbert Schroter

Eckehard Stein

Werner Dennhardt

Horst Hilgers

Dorothee Griesch

Peter Schwagler

Kurt Albrecht Wehlmann

Alexander Planz

Disclosed is a device for dosing light from a light source in accordance with the intensity of light impinging upon a material to be exposed, comprising: a photosensitive element located in the beam path of the light source, comprising a photoresistor having an ohmic resistance inversely proportional to the intensity of light impinging thereon and providing an output voltage; a capacitor arranged in series with the photosensitive element; means, preferably in the form of a switch bridging the capacitor, responsive to switching-on of the light source for initiating charging of the capacitor; switching means arranged in series with said capacitor for varying the charging time thereof, whereby the exposure time of said material to be exposed can be varied by a predetermined ratio to produce a desired shade of gray; optional means for amplifying the output voltage of the photosensitive element; means for comparing the output voltage of the photosensitive element with a reference voltage to produce an output signal; and means for controlling the amount of light impinging upon the material to be exposed in response to the output signal from the comparing means.

Light dosing device

This invention relates to an improvement in a developing apparatus, especially as part of a photoprinting machine, for developing diazotype copying material capable of being developed by an atmosphere containing gaseous ammonia and water vapor, including a developing chamber comprising at least one first, heated, inclined evaporator trough to which fresh ammonia is adapted to be fed at one side while ammonia water with a reduced ammonia content is adapted to be drained off at the other side, the ammonia water with the reduced ammonia content being adapted to form a pool, and further comprising a siphon through which the ammonia water with the reduced ammonia content and condensate formed in the developing chamber are adapted to be drained off, the improvement that the siphon forms part of an evaporator arranged outside of the developing chamber from which a developer gas pipe leads into the developing chamber, and further comprising a, preferably unheated, reservoir for the ammonia water with the reduced ammonia content adapted to flow from the evaporator trough, the reservoir substantially covering the entire floor space of the developing chamber and being completely open at its top, having an opening which leads to the outside evaporator and being positioned in the chamber at such a level that the bottom of the reservoir is adapted to be completely covered by the pool of ammonia water with reduced ammonia content. The invention also relates to a method of operating the developing apparatus.

Developing apparatus for diazotype material, especially for use in a

The invention is an improvement in an apparatus for developing sheets of diazotype copying material by the semi-dry process and includes at least two rotatable rolls being biased together with a gap between them for passage of the sheets of diazotype material, with an additional force being exerted on at least one of the rolls which force transfers a plane of deflection of one of the rolls to a position outside of a principal plane in which axes of the rolls are located in such a manner that a first line of intersection between the plane of deflection and the shell of the aforesaid one roll, starting from which line of intersection the deflection is directed toward the roll axis, extends in front of the gap, when viewed in the rotational direction of the roll, first guides to bring sheets of diazotype copying material into contact with the roll at a first transition line between the first line of intersection and the gap, and second guides to lift the sheets off of the roll behind the gap at a second transition line located before a second line of intersection between the plane of deflection and the aforesaid shell of the roll, starting from which second line of intersection the deflection is directed away from the roll axis.

Apparatus for developing sheets of diazotype copying material by the

This invention relates to an improvement in a feeder mechanism at an exposure station of a photoprinting machine, in which a transport device is connected to a first rotary drive for transporting a copying material through the exposure station and in which a second rotary drive is provided which may be operated at variable speeds relative to the speed of the first rotary drive and which is connected to a roller at the beginning of the transport path of an original to be copied, the improvement comprising an additional pair of preceding rollers positioned in the transport path of the original upstream of the transport device in the direction of transport, means connecting said pair of preceding rollers to said variable speed second rotary drive which may be switched in order to drive said pair of preceding rollers optionally at a speed corresponding to the transport speed of the transport device or at a lower speed, switching means in the transport path between said pair of preceding rollers and the transport device, means connecting said switching means to the variable speed rotary drive of the pair of preceding rollers whereby their speed is lower than the transport speed as long as the switching means are in a first switching position, not actuated by an original, and the speed of the preceding rollers corresponds to the transport speed when the switching means are changed to a second switching position by an original to be copied.

Feeder mechanism at an exposure station of a photoprinting machine

This invention relates to an improvement in the process for the production of photocopies with two-component diazotype material which cannot be developed by the action of heat alone and which, during continuous passage through a photocopying machine, is first exposed imagewise to light emitted by a mercury lamp and is then exposed, for the purpose of development, to an ammonia/water mixture, in vapor form, in a development chamber, the improvement comprising employing light emitted from a gallium-modified or indium-modified mercury lamp for the imagewise exposure of the diazotype material, and exposing the diazotype material, which has been exposed to light, to an ammonia/water vapor mixture in the development chamber, said mixture in terms of vapor pressure being unsaturated and containing at most 25 per cent by weight of ammonia, at a temperature of about 105 to 120.degree. C and at a predetermined pressure. The invention also relates to an apparatus for performing the process.

Process and apparatus for the production of photocopies using

In a diazo copier, a first developing chamber for developing a diazo material employing an ammonia-containing vaporous developer, a second chamber adjacent an output aperture of the first developing chamber, a source of heat, and a suction device for drawing off developer escaping from the second developing chamber through an output aperture and for removing developer from the diazo material are provided. A rotatably mounted porous hollow roller means forms part of said suction device positioned in said second chamber and a suction duct means is connected to said roller means. A transport means which is not in heat-conducting connection with the source of heat is provided for bringing the copying material in contact with the hollow suction roller means.

Apparatus for developing a photosensitive material using a vaporous

This invention relates to a developing apparatus for light-sensitive material comprising elongated open trough means, partition means in said trough means dividing said trough means into sections, means providing communication between said sections, inlet and outlet means for said trough means, said inlet means being adapted to introduce solution into one of said sections and said outlet means being adapted to remove solution from another of said sections, heating means in said section containing said outlet means and being positioned below an opening of said outlet means in said trough means, and temperature sensor means connected to said heating means via thermostat means.

Developing apparatus for light-sensitive materials comprising an

This invention relates to an improvement in a copying apparatus, particularly a photoprinting apparatus, comprising an exposure station, a developing chamber, and an evaporator associated with the developing chamber, in which a developer composed of an ammonia/water mixture is virtually completely evaporated and over-heated at a temperature about 100.degree. C, preferably about 105.degree. C, and at a predetermined pressure, preferably atmospheric pressure, the apparatus further including, for dosage of the ammonia/water mixture, a feed pipe connected with the evaporator, a valve connected with the feed pipe, and a control unit connected with the valve, whereby the rate of feed of the ammonia/water mixture may be adapted to different operating conditions, the improvement comprising first switch means, actuatable by an original, positioned at an entrance for the original upstream of an exposure station in the feed direction of the apparatus. Second switch means, actuatable by a copying material, positioned at a delivery point of said copying material downstream of said developing chamber, control unit means electrically connected with said first and second switch means, said control unit being so constructed that after said first switch means has been switched to a first position by the original, the valve is first opened for a relatively long period of time, and the valve is then alternately opened and closed, in accordance with pulses, as long as the first or second switch means is maintained in its first switching position by one or more originals or one or more sheets of copying material, respectively, and said pulse-wise opening and closing of the valve is terminated only when neither the first nor the second switch means is maintained in its first switching position by an original or a sheet of copying material, respectively.

Copying apparatus, in particular photoprinting apparatus, comprising a

This invention relates to a method of exposure control in photographic printing apparatus for printing from originals made on different types of photographic material, the method comprising:

Methods and apparatus for automatic exposure control

In a photoprinting machine including a developing chamber in which a web of exposed diazotype paper continuously fed at an adjustable speed is developed with a developer medium composed of a vaporous ammonia/water mixture, an after-treating chamber following next in the direction of feed of the diazotype paper and which is connected with a device for removing ammonia-containing exhaust air, and a device for expelling developer medium from the developed diazotype paper. The expelling device includes a high energy infrared radiator positioned opposite the web in the after-treating chamber, a connection between the high-energy infrared radiator and an output of a heat output control device, and an input for the heat control device connected to a transmitter of the feed speed. The heat output control device having a characteristic such that the heat output of the high-energy infrared radiator is proportional to the feed speed and the color temperature of the high-energy infrared radiator is about 2000.degree. K at the maximum feed speed of the diazotype paper.

Photoprinting machine with a device for expelling excess

This invention relates to an improvement in a device for adjusting an original to be copied, in particular an original which is repeatedly conveyed through the exposure station of a photocopying machine, including a transport mechanism with a deviatable transport band arrangement adapted to transport said original at a variable speed, and when said original is to be copied a number of times, in a closed path, further including a device for lengthening the path on one side, two switches positioned transversely and normal to the direction of flow and adapted to be actuated by the original whereby a switching circuit to a servomotor is closed when the leading edge of the original deviates from a correct position, said servomotor being connected to a correcting element adapted to change the length of the path of the original on one side of said transport band arrangement, the improvement comprising generator means adapted to put out a first signal proportional to the transport speed of said original, said servomotor having a rotational speed proportional to a second signal supplied thereto, and means connecting said generator means to said servomotor by at least one transfer element adapted to proportionately transform or transduce said first signal into said second signal.

Device for adjusting an original to be copied

This invention relates to a developing device for printing plates comprising a developing chamber, rotatable printing plate support means in said chamber, spray nozzle means directed at said printing plate support means, vertically reciprocatable rotatable brush means mounted above said printing plate support means, means for supplying fluid to said spray nozzle means, and means for actuating said printing plate support means and said brush means.

Developing device for printing plates

This invention relates to a process for the transport through a copier of an original having a leading and a trailing edge, which comprises transporting the original at least once along a path wherein it passes in the stated order a third point, an illumination zone, a fourth point, a first point, a second point and, if transported more than once, the first point again wherein if the trailing edge has not passed the third point when the leading edge passes the second point the path length between the first and second points is extended and wherein if the trailing edge has not passed the second point when the leading edge passes the first point the path length between the illumination zone and the first point is extended and wherein the speed of the original past the first point may be increased relative to its speed in the illumination zone at least while an extended path is followed between the zone and the first point and after the trailing edge has passed the second point. The invention also relates to an apparatus for performing the process.

Process and apparatus for transport of originals in a reproduction

In an apparatus for producing from a developer solution a gaseous developer medium for diazotype materials, which apparatus includes an inclined surface for passing the developer solution through a vaporizing region from a first end to a second end thereof, heater elements disposed along the vaporizing region, the temperature in the region of the second end being at least 25.degree. C higher than the temperature in the region of the first end and the temperature increasing with the distance from the first end, and a sipon at the second end for collecting the condensate of the vaporized solution. The siphon has a heater element for heating the solution collected therein to the temperature prevailing in the region of the second end to release more gaseous developer medium before the solution leaves the vaporizing region.

Apparatus for producing a developer medium for diazotype materials

A process for replenishing developing medium in a developing chamber of a photoprinting machine and apparatus for performing the process. The process and apparatus for performing it utilizes at least one photocell in combination with various electrical and optical elements for measuring the concentration of developing medium in the developing chamber, comparing the measured value to a nominal value, and controlling the replenishing of the developing medium correspondingly.

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Taunusstein, Germany

Herbert Schroter