US3122981A - Gaseous photo-developing apparatus - Google Patents

Description

2 Sheets-Sheet 1 V III III INVENTORS M. ELLIS P NEEB flTTOENEr' ROBERT ROBERT BY R. M. ELLIS ETAL a Q Q Q 8 Q GASEOUS PHOTO-DEVELOPING APPARATUS March 3, 1964 Filed 001;.

R. M. ELLIS ETAL 3,122,981

GASEOUS PHOTO-DEVELOPING APPARATUS 2 Sheets-Sheet 2 March 3, 1964 Filed Oct. 20,1961

INVENTO ROBERT M R0 as RT HTTORNEY United States Patent 3,122,981 GASEOUS PHOTO-DEVELGPING APPARATUS Robert M. Ellis, Basking Ridge, and Robert P. Neel), Franklin Park, N J assignors to Rotolite Corporation, Stirling, N1, a corporation of New Jersey Filed Get. 20, 1961, Ser. No. 146,510 1 Claim. (Cl. 95-94) The invention relates to photo-copying duplicators or printing apparatus of the type wherein photo-sensitive sheets of base material (generally paper)-having in one face a photosensitive emulsion coating of the diazo typeare, after exposure, to be treated with ammonia water vapor for the development of the latent image. It is directed more especially to novel apparatus for elfecting such development by the vapor as generated from ammonium hydroxide or the like. Coated paper commonly used in the reproduction of engineering drawings, business papers and the like, may readily be processed in said apparatus, such papers being referred to, generally, as of the diazo" type which produce right-reading copiesthe reproduced image being of a color depending upon the particular diazo compound utilized.

In operating with this type of paper in conventional machines, the light passing through a more or less translucent original to the sensitized (coated) copy sheet will then burn off the sensitized coating in passing through such original. The dark or opaque portion, however, will not permit light passage and thus prevents such burn off. Upon subsequent development or exposure then to, for example, ammonia vapors, an exact copy of the original is reproduced.

Apparatus for carrying out of the development of the aforesaid prints, comprises, generally, means for effecting association temporarily of a source of ammonia gas with a means for advancing an exposed photo-sensitive sheet for subjection to said gas.

Broadly, it is an object of the present invention to provide a novel, simplified, trouble-free and inexpensive construction of such apparatus-more especially in relation to the delivery of the gaseous medium (ammonia vapor) to a previously exposed, sensitized sheet as traveled through a portion of the apparatus, said sheet then being directly associated with the said gaseous medium.

An important object of the invention, also, is to effect the said developing operation without incurring moisture condensation problems prevalent in currently used apparatus of this nature.

Another object of the invention is to provide apparatus of the aforesaid nature whereby operation will be facilitated, more especially with respect to the contact relationship of the light-exposed, sensitized sheet with a selected developing agent-generally gaseous ammonia vapor; also, to the provision of apparatus which lends itself to operation either in a table top or in a wall mounted position.

A still further object of the invention is to provide, for use in such apparatus, a trouble-free ammonia feed; and one with which objectionable volumes of ammonia vapor are prevented from escaping to the surrounding atmosphere.

The invention contemplates, moreover, the provision of a novel means for applying heat to the developing agent during operation of development; and, also means for minimizing the development of moisture condensation in areas where such condensation could contact and stain the sensitized sheet being developed.

In carrying out the invention-it being noted that diazo type coatings are available in various colors and combinations thereof, and that some heat and moisture should be present in the developing agent to develop adequately the full range of colors-the ammonia gas is associated with "ice the said diazo type material through perforations in a flexible slip-screen.

Between this screen and an associated tubular roller, the sensitized paper is then advanceda substantial area of the perforated portion of said screen being arranged for contact with the periphery of said roller in the advance of copy by the latter. The said roller thus substantially seals outward flow, through the perforations, of ammonia gas; and thus serves to obviate excessive leakage thereof externally of the apparatus. Such apparatus is otherwise to be sealed olf from ammonia gas supplythe said screen in some portion of the contact area and beyond being imperforate.

Furthermore, a novel arrangement whereby to furnish heat is, in accordance with the invention, to be associated with the aforesaid roller at a location where it will be most effective and will, also, obviate problems of moisture condensation on the prints.

In accordance with common practice, the location of an ammonium hydroxide retaining vessel should be at the hottest section of the ammonia chamber. However, this results in vapor condensation at areas where high temperatures cannot ordinarily be maintained-particularly where constant passage of papers tends to reduce the tem perature of the surrounding structure. It is common practice, also, to correct such condition by the installation of additional, strategically located heaters. The location of a perforated exposure surf-ace also may be arranged at the upper portions of an ammonia chamber so that vapor condensate will tend to fall away and thus avoid staining of the sensitized surface of a print-as would result from wetting of the same. In the case of the novel construction, however, the heat is applied solely to the said associated roller, and at a point external to the gaseous cham ber associated therewith. Such application of heat will then produce maximum molecular activity of the gaseous medium as applied to the paper fed over the surface of said heated roller.

The nature of the invention, however, will best be understood when described in connection with the accompanying drawings, in which:

FIG. 1 is a front elevation of the novel photo-developing apparatus.

FIG. 2 is a horizontal section therethrough, taken on the line 22, FIG. 1 of the drawings, and looking in the direction of the arrows.

FIG. 3 is a transverse section on an enlarged scale, taken on the line 33, FIG. 1, and looking in the direction of the arrows.

FIG. 4 is a fragmentary, longitudinal section, on an enlarged scale, taken on the line 44, FIG. 2, and looking in the direction of the arrows.

Referring to the drawings, the novel photo-developing apparatus comprises a suitable supporting base in the form, for example, of a box-like structure 10 which supports preferably a switch 11 at the rear for electric control of the developing operation, as will hereinafter be more fully set forth. Along the paper-discharge (rear) side, the box-like unit may be provided with an outwardly-extending flange 12 having key-hole slots 13 whereby to suspend for operation the unit in a vertical or wall-hanging position.

To the top of the box 10 there is attached an inwardly inclined guide strip 14 for guiding exposed prints to the one side of the ammonia-applying region, as will here inafter be more fully set forth. Similarly, along the opposite side, there is secured a discharge strip 15-said strips cooperating with corresponding inturned wall portions 14, 15 of a gas-retaining housing 16 to afford respective inlet, outlet channels for a print 17, respectively a a to and from an intermediate feed roller 18 which is supported on an operating shaft 19.

Mounting of the gas-retaining housing 16 on the aforesaid box-like structure 10, moreover, is such that it is possible to apply suitable tension to a perforated, arcuate strap or slip-screen 29 which serves then to close the gap between the inturned portions 15 of the said housing 16. The latter to this end is supported pivotally along the rear, as upon brackets 21; and there are provided at the front inwardly turned and threaded brackets 22 designed to receive adjusting screws 23 passing freely through the top of the box-like structure 1tl-re spective springs 24 being introduced between said structure and the corresponding head of a screw. The mounting is such that the required tensionto minimize leakage of gas through the perforations of the screen or strap during operationis readily attainable by correspondingly adjusting the screws 23.

The said slip screen or strap 20 thus is formed over an open section of the bottom of the gas-retaining housing 16 as a transverse, flexible and more or less semicircular section or strap portion which conforms to and fits snugly then over a portion of the surface of roller 18. This section of the slip screen between which and the periphery of said roller a print is designed to pass upon rotation of said roller, is of a more or less flexible material such as Teflon; and is perforated substantially over the contacting area, such that ammonia fumes will then pass readily therethrough to act, however, only on a passing, underlying print for the development of its previously exposed emulsion portion, as is Well understood.

Moreover, such contact strap portion should be composed of a material having a very low coefficient of friction, for example, so as to be held in a close-fitting wrap part of the way (approximately 145) around the heated roll surface and still permit papers being developed to move with the surface of the roller, which has a relatively higher coelficient of friction, as it rotates about its axis.

The partially perforated strap, the cover and its turnedin portions 14 and 15' together with the closely fitted end walls 16', 16" thus form a sealed gas chamber except for'the perforations of the slip screen. Ammonia vapor is always available on the surface of the roller through the perforations but in efiect is wiped off and returned to the chamber as the smooth surface of the roller passes each perforation. Ammonia vapor is also available in the same manner with respectto papers passing through the developing area, but is absorbed into the relatively porous sheet in quantities suficient to effect development of the diazo chemicalsexcessive vapors being wiped off as hereinbefore described. The-only vapor to pass out of the apparatus is that whichis carriedby the structure of the paper itself.

The ammonia vapor for such development is continuously to be supplied to the interior of the housing 16, as from an insertable, tubular tray element 25 which is sealed at its inner end and is designed to retain a charge of the ammonium hydroxide. To this end, the said tray element is provided with an upper, longitudinal discharge opening 26 which is, preferably, extended more or less laterally and along the said tubular tray to an appreciable dimension within the sealed gas chamber. The said opening 26 thus permits free vaporization of ammonium hydroxide into the chamber; and its angular position allows of the filling (partial) of the tray with the ammonium hydroxide when the printing apparatus is utilized either in a horizontal (table top) or a vertical (wall hanging) operating position. The said tray element 25 projects, at its filling end, slightly beyond the housing 16; and it is connected, through an intermediate reduced sleeve portion 27, to an end fitting 28 which is provided with the filling opening 29. The said fitting serves then not only as a means of filling and draining of the tray; but, if said fitting be constructed of transparent material, will serve as well as a liquid level gage.

A set screw 31), fitting a peripheral groove 31 in the outer, reduced end of the said tray element 25, may serve to lock said fitting against longitudinal displacementthe former being sealed rotatably tothe try element by means of an 0 ring 32.

To effectthe heating of the roller during operation, the one end of the said roller is equipped with a rotatable slip ring 33 for supply of electric current from leads 33 to a loop 34 of resistance Wire. The latter is helically wound about the shaft 19, the power supply being under control of the switch 11 which supplies, also, power to a motor 35 for effecting rotation of the said roller 18, as well as a fan 36.

The exposed sheet thus advanced becomes heated between the roller surface and the slip screen, thereby materially increasing the molecular activity of the said gaseous agent which results in a substantially increased production rate.

We claim:

Apparatus for the production of photo-mechanical prints on diazo-type papers, comprising: a base, and a housing mounted thereon affording an elongated, ammonia-retaining exposure chamber with elongated bottom opening; a resilient strip of non-porous material secured over said opening, inwardly directed into said chamber and having an arcuate section thereof perforated for discharge of ammonia gas directly to the surface of an inserted sheet; a roller external-1y contacting the said perforated area thereof as Well as non-perforated portion beyond the same, said non-perforated portions sealing the exposure chamber against leakage; and an operative shaft for said roller, extending externally of the housing, to effect its rotation and to advance thereby an exposed print to the contacting area wherein the ammonia exposure chamber contains an externally scalable ammonia supply tray whichis mounted therein and provided with a longitudinal opening so arranged as to disehargegas into the exposure chamber when the apparatus is used in either its horizontal or vertical operating position.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS 462,971 Great Britain Mar. 18, 1937

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