Radiant energy – Corona irradiation
Patent
1994-01-31
1995-12-26
Berman, Jack I.
Radiant energy
Corona irradiation
15 151, 361213, 361214, H05F 304
Patent
active
054790140
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the cleaning of products in sheet, strip or film form and concerns in particular the cleaning of or removal of dust from strips of unexposed photosensitive product which have to be packaged, after manufacture, in any appropriate form suitable for the subsequent direct use.
The industrial production of strips of unexposed photosensitive product long ago encountered the problem of the elimination of manufacturing waste, such as perforation particles and dust which adhere to the faces of the product in strip form, usually by electrostatic effect.
The presence of such dust or particles must be considered to be incompatible with obtaining a product of reproducible good high quality, since such particles of dust are responsible for damage to the product by mechanical effect or impairment of the image by electrochemical action.
With a view to dealing with the above problem, the prior art reveals a number of proposed solutions such as the one provided by U.S. Pat. No. 4,469,275 which teaches that an endless strip should be caused to follow a curved path so as to apply, to one of its convex faces, an air jet, curtain, wave or flow blowing in the opposite direction to movement of the strip. Such a solution does not appear to resolve completely the problem posed, because of the local treatment on only one face of the product and problems of pressure equilibrium on each side of the film which has to be regulated in order to avoid vibration of the film.
U.S. Pat. No. 4,194,232 teaches a method of simultaneous treatment of the two faces of the film which is also subjected to a flow of ions. U.S. Pat. No. 4,454,621, U.S. Pat. No. 4,241,377 and U.S. Pat. No. 4,750,080 can also be cited. Although in principle the solution taught by these patents may be considered suitable for assuming the function of cleaning and dust removal, the ionisation means are not compatible with the cleaning of a strip of unexposed photosensitive product. In fact, the functioning of an ion emitting device produces a glow emitted by corona effect and such a glow is responsible for the formation of latent images on the strip of unexposed photosensitive product. The quality of the basic product which was to be suitably cleaned is thus greatly impaired, to an unacceptable extent.
U.S. Pat. No. 3,409,768 describes an apparatus for treating the surfaces of a web of photosensitive material, and more particularly to an apparatus which generates a flow of ionized gas that is applied to a surface of the material for altering or neutralizing any electrostatic charge thereon and for removing any particulate matter therefrom, the apparatus including a corona discharge means and means for shielding the surface of the material from any irradiation generated by the corona discharge means.
The purpose of the invention is to remedy the above drawbacks by proposing improvements to an apparatus for cleaning an unexposed photosensitive product. Specifically, in addition to means for blowing and suction by air curtain or air wave, means of ionising the dust and particles are provided so as to assist the separation of the latter and their take-up by the flow of suction or cleaning air, without the production of the ionisation field leading to any impairment of the coating or sensitive layer on the unexposed photosensitive product.
To achieve this purpose, the cleaning apparatus of the invention is of the type including a channel through which the strip can run in one direction of movement; a treatment area established transversely to the direction of running of the strip and over the entire width of the strip, the treatment area including means for sweeping both surfaces of the strip with a curtain of air flowing in the opposite direction to the strip; and at least one electrode connected to a high potential and intended to produce local ionisation by corona effect, characterised in that the electrode is enclosed in an insulating housing connected to the said channel by an antihalo duct, the housing is swept by a light flow of air, so as
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Berman Jack I.
Eastman Kodak Company
Parulski Susan L.
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