US 3249738 A
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y 1966 w. SIMM ETAL 3,249,738
APPARATUS FOR PRODUCING PHOTOGRAPHIC IMAGES AND PRINTING PLATES Filed Jan. 22, 1965 INVENTORS I WALTER S/MM, H/LDEGARD, HAYDN.
CM L448 TORNEVS) 3,249,738 APPARATUS FOR PRODUCING PHOTOGRAPHIC IMAGES AND PRINTING PLATES Walter Simm, Opladen, and Hildegard Haydn, Leverkusen, Germany, assignors to Agfa Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany Filed Jan. 22, 1963, Ser. No. 253,150 Claims priority, application Germany, Feb. 10, 1962,
4 Claims. (Cl. 219216) The invention relates to an apparatus for producing photographic images and printing plates from a lightsensitive layer exposed to form an image and a transfer layer in which apparatus the layers are pressed together and are heated. Images of opposite gradations are produced in the light-sensitive layers and in. the transfer layer: a negative image is produced in the light-sensitive layer and a non-laterally-reversed po s-tive copy of the original to be reproduced is obtained in the transfer layer.
Examples of light-senstitive layers are silver halide emulsion layers which contain tanning developers. If these layers are heated after they are exposed to form an image, the exposed areas are hardened, while the unexposed areas are transferred to the transfer layer and serve to produce a positive image. obtained relief images which can be used as printing plates. It is also possible to work with silver halide emulsion layers containing developer substances and with transfer layers which contain substances producing.
colored compounds with the developer substances. During heat development, the developer substances are transferredfro'm the unexposed areas to the transfer layer and there converted byreaction with the substances contained there into color images. Those on the exposed areas have been used up for developing the exposed silver halide. Suitable materials for carrying out these processes are set out in German patent'specifications No. 895,101, 1,003,577, 1,004,043 and 1,015,313 and in German Auslegeschrift 1,002,628.
The aforementioned patent specifications disclose the use of drying drums 'which can be heated electrically, to heat the layers and to press them together. -In such apparatus, the papers are pressed, by means of a waterpervious cloth, onto a heated metal support. It has, however, been found that inconsistent results are obtained when using such apparatus.
Heat-copying apparatus is also known which comprise essentially an endless plastic band, which is guided over a plurality of guide rollers, and-a heat radiator, which supplies byradiation the heat necessary to develop the image. The guiding means are such that the heat-sensitive paper and the original are pressed, one against the other, between the band and a guide pulley and are irradiated through the band. The copy is formed by imagewise heating of the heat-sensitive paper, initiating a reaction which blackens the paper. Apparatus of this type is not suitable for the aforementioned heat-development processes, since .these require entirely different conditions.
It has now been found that these disadvantages may be avoided and that satisfactory results may be obtained by using apparatus in which the aforesaid layers are pressed together and heated by a heatable means having water- 'impervious, pressure-tight surfaces.
United States Patent In this way there are having run over the guide rollers, is 20 to 70 C. lower than the temperature of the drum surface by cooling during travelling. The temperature of the drum is kept at to 250 C., preferably at 150, and is regulated by any conventional andjusting and maintaining device.
In order to produce satisfactory results, it is expedient to moisten the photographic materials'with water before introducing themyinto the heating zone. For this purpose, there are used moistening cylinders which are so arranged that the photographic materials are moistened from the rear under pressure. 4
In the present invention the photographicmaterials to be processed in the present apparatus are pressed, one against the other, in a closed space with the simultaneous action of moisture; the steam formed from the moisture cannot escape outwardly, but is forced, under pressure, on to the photographic layers. Withthe heating presses and drying drums hitherto employed, these conditions could not be obtained, since a vapor-pervious and waterpermeable cloth is used. It is, moreover, desirable for the developing process that there be a temperature drop of 20 to 70 C. perpendicular to the plane of the layers which are heated and pressed together.
The rotational speed of the heating drum is preferably so regulated that the photographic layers remain a few .seconds, for example, 5 to 10 seconds, in the heating zone. The pressure exerted'by the endless band on the heating drum is adjusted by means of adjustable guide rollers, preferably to 0.3 to 2 kg./cm.
One embodiment of the apparatus according to the invention is shown diagrammatically in the accompanying drawing in which the apparatus consists of a drum 1 which can be heated electrically and against which an endless band 2 of temperature-resistant, elastic, waterimpervious and vapor-tight material of low heat conductivity is so pressed that it covers a part of the drum periphery, for example half, and almost the full width of the drum. The width of the band must also be greater than the Width of the negative or positive material. A sealed development and transfer zone is then formed between the drum surface and the band by applying strong pressure to the band.
The said elastic band can be produced of any material which meets the conditions disclosed above. Suitable are,
for example, silicon rubber on the basis of dimethyl polywith drum 1 and is heated to the reaction temperature,
does not come into contact with any other (colder) elements as it runs over the three guide rollers. As a result, after a few revolutions, the surface temperature of the band, at the point of contact between the roller 3a and the drum 1, is only slightly lower (20 to 70 C.) than the temperature of the drum surface. Since the photographic materials 4a and 4b are introduced at this point,
there will be the necessary temperature drop across them and, in travelling from the point of insertion between 1 and 3b, they are given the further treatment according to the other conditions required. The temperature of the drum 1, into which an elecrtical heating arrangement is incorporated, is adjusted so as to be substantially constant, by regulating members which include a fixed rodlike bimetallic strip 5, which projects axially into the rotatably mounted drum and which assumes, mainly by heat radiation, the temperature of the heated wall of the drum '1.
The roller 3c is so mounted that the mounting may be displaced in the direction indicated by the two arrows and thus the band tension can be adjusted. Since it is desirable for the pressure of the band on the drum at the end of the developing and transfer zone, i.e., the pressure between the drum 1 and roller 3b, to be adjustable, the mounting or bearings of the roller 3b may also be displaced inthe direction indicated by the arrow by pressure screws 6 on both bearings.
The support material is moistened by two moistening cylinders 7a and 7b, which are covered with absorbent elastic material and one of which may be immersed in a tank filled with water. The cylinders 7a, 7b are so driven, through gearwheels 8a, 8b, 80 from the roller Bar, that a foil pushed a suitable feeding speed between the moistening cylinders. is guided to the inlet position between 3a and 1.
To strip the supporting foils from the drum 1 after they have travelled through the development and transfer zone, a stripper plate 9 is arranged in the position indicated.
1. Apparatus for producing photographic images for a heat transfer process from a supported light-sensitive silver halide emulsion layer being image wise exposed, developed and heated while in contact with a supported transfer layer, comprising a rotatable drum disposed for receiving the supported layers with said layers contacting the surface of said drum at a feed portion and leaving the surface of said drum at a discharge portion, moistening means disposed adjacent said feed portion of said drum whereby the layers are passed through said moistenin g means and on to the surface of said drum, heating means for heating said drum, said drum having a vapor tight and water impervious surface upon which the layers are in contact, a movable endless belt contacting said surface of said drum between said feed portion and said discharge portion whereby said belt and the portion of said surface of said drum contacted by said belt form a heating zone,
said endless belt being of a water-impervious elastic material of low thermal conductivity whereby said heating zone is water impervious, said endless belt having a temperature between 20 and C. lower than said surface of said heating drum, and adjust-able guide means maintaining said belt in close contact with said surface of said drum.
2. Apparatus according to claim 1 in which stripping means are disposed at said discharge portion of said drum for separating the layers from said drum.
3. Apparatus according to claim 1, in which said heating means includes a fixed bimetallic rod projecting axially into the rotatably mounted drum.
4. Apparatus according to claim 1, in which the moistening means consists of two moistening rollers positioned on opposite sides of and disposed for contacting said layers with the centers of said rollers substantially aligned with the point of contact of said rollers and said layers whereby said layers are simultaneously moistened by pressure from one side.
References Cited by the Examiner UNITED STATES PATENTS 2,571,426 10/ 1951 Doniak 219-469 2,770,534 11/1956 Marx 250-65.1 2,891,165 6/1959 Kuhrmeyer et .al. 250-651 2,927,210 3/1960 OMara 25065.1 2,986,987 6/ 1961 Limberger -89 3,012,141 12/1961 Thomiszer 250-65.1 3,027,822 4/ 1962 Frantz 95-89 3,060,023 10/1962 Burg et a1. 101-1494 3,100,702 8/1963 Rauner et al 250-651 3,142,241 7/ 1964 Limberger 95-89 3,148,612 9/1964 Jacobs et al 95-89 3,155,024 11/1964 Land 95-89 X RICHARD M. WOOD, Primary Examiner.
RALPH R. NILSON, C. L. ALBRITTON, W. F. LIND- QUIST, Examiners.