Conveying roller for photosensitive material and method of producing the same

Abstract: Continuous photo film (11) includes a support (11a) of resin film having a back surface. A photosensitive layer (11b) of photographic emulsion is disposed on a surface of the support opposite to the back surface. A conveying roller conveys the continuous photo film. The conveying roller includes a roller body (31) of metal. A hardness reinforcer layer (32) is formed on a surface of the roller body by thermal spraying and from ceramic or cermet, and avoids being scratched or ground by the back surface.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveying roller for photosensitive material, and a method of producing the same. More particularly, the present invention relates to a conveying roller for photosensitive material, which has high resistance to abrasion and can be produced easily, and a method of producing the same. 2. Description Related to the Prior Art Photosensitive material, in general, is constituted by a support and a photosensitive layer of photographic emulsion, which is applied as a coating to, or deposited to, the support. According to various kinds of the support, there are plural examples of photosensitive material, including photo film, dry plate, and photographic paper. The photo film has the support produced from film of resin. Types of the photo film includes a roll photo film and a sheet photo film. Examples of the roll photo film include the 8 mm type and the 1,000 mm type. Examples of the sheet photo film include types of 4 x 5 cm, the cabinet size (halfplate), B5, A4, B4, A3 and 25.4 x 30.48 cm ( 10 x 12 inches). As a form of the most widely used photo film, a photo film cassette is well-known, and includes a cassette shell, a spool rotatable inside the cassette shell, and a strip of the photo film whose end is retained on the spool and which is wound about the spool. The photo film is conveyed by conveying rollers in optical instruments. Conveying rollers for use in the photo film manufacturing apparatus, a photographic printer and a photo film processor are constituted by a roller body formed by cutting and scraping a rod of stainless steel, or by a roller body of metal and hard chromium plating formed on its surfaces. To avoid damaging continuous photo film and photo filmstrip in conveyance, a surface of the roller is finished by polishing, and smoothed for the contact wit the photo film. There is a type of photo filmstrip including a magnetic recording layer, which is a coating of magnetic material applied to the support on the side opposite to the photosensitive layer, so that the photo filmstrip can operate for storing magnetic information written thereto. There is abrasive material or polishing agent, mixed with the magnetic material, for contacting a magnetic head of an information reader/writer, to remove dust or dirt from the magnetic head. When a conveying roller contacts the continuous photo film which will become this type of photo filmstrip, the conveying roller is abraded and deformed by the abrasive material of the photo film, because the conveying roller contacts the magnetic recording layer. It is likely that the continuous photo film or photo filmstrip is fogged by pressure, scratched or damaged. A life of the roller is short, so that each roller must be replaced with an unused one very frequently. To solve those problems, JP-A 8-262680 (corresponding to U. S . Pat. No. 5,520,601) discloses a use of such ceramics for a conveying roller as yttria-alloyed tetragonal polycrystalline zirconia, which is zirconium oxide and yttria mixed therewith at 3-5 mole %. Ceramics characteristically have a higher hardness than stainless steel and hard chromium plating, and have higher resistance to abrasion. However it is difficult to cut or scrape a ceramic product into a complicated shape due to the considerable hardness of the ceramics. Ceramics are unsuitable for shaping the roller which includes a roller core and flanges on respective ends of the roller core, and in which a diameter of the roller core is partially changed. Moreover a problem lies in that zirconia stabilized by use of yttria is likely to collect static charge electrically. The continuous photo film might be fogged and have a lowered quality. DE-G 8102225.5 describes a conveying roller having a high surface quality and an especially high wear resistance. A surface quality is achieved by anodic direct current oxidation of an aluminum body in a wet chemical process. EP 0401886 describes a roller comprising a thin seamless metal sleeve at its surface which is provided with a surface structure for preventing the formation of an air cushion when such roller is used for guiding or supporting a moving web-type substrate. Such surface structure is further protected with a wear-resistant top layer of ceramic, glass, quartz or polytetrafluoroethylene. EP 0651385 describes a tape driving apparatus having a capstan axle and a pinch roller which presses a magnetic tape to the capstan axle, in which the capstan axle has, as an outermost layer, a diamond-like carbon film having a Knoop hardness of at least 5,000 kg/mm 2 , and a density of not larger than 3 g/cm 3 , which has high reliability and good driving performances. This results in an increase of the tape driving force by utilizing frictional sliding characteristics and wear resistance of the diamond-like carbon film. SUMMARY OF THE INVENTION In view of the foregoing problems, an object of the present invention is to provide a conveying roller for photosensitive material, which has high resistance to abrasion and can be produced easily, and a method of producing the same. The above and other objects and advantages are achieved according to the present invention by a conveying roller having the features of claim 1 and by a method of producing a conveying roller having the features of claim 4. The photosensitive material further includes a magnetic recording layer, formed on the back surface of the support, and including magnetic material and polishing agent. The conveying roller includes a roller body of metal. A diamond-like carbon coating is formed on a surface of the roller body by ion plating method, for avoiding being scratched or ground by the back surface. Furthermore, the roller body has a surface of which at least one portion is polished and smoothed, and the at least one portion contacts the photosensitive material via the diamond-like carbon coating. Consequently in the present invention, the conveying roller for photosensitive material can have high resistance to abrasion and can be produced easily. BRIEF DESCRIPTION OF THE DRAWINGS The above objects and advantages of the present invention will become more apparent from the following detailed description when read in connection with the accompanying drawings, in which: Fig. 1 is an explanatory view illustrating a photo film manufacturing apparatus; Fig. 1A is an explanatory view in cross section, illustrating a layered structure of photo film; Fig. 2 is an elevation illustrating a conveying roller with the continuous photo film; Fig. 3 is a perspective illustrating the conveying roller and the continuous photo film; and Fig. 4 is a cross section illustrating the conveying roller and the continuous photo film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION In Fig. 1, a photo film manufacturing apparatus 10 is illustrated. The photo film manufacturing apparatus 10 produces photo film to be used in a photo film cassette. The photo film manufacturing apparatus 10 is constituted by a photo film supplier unit 12, a perforator unit 13, a side printer unit 14 and a cutter unit 15. Continuous photo film 11 is basically constituted by a support 11a and a photosensitive layer 11b. See Fig. 1A. The support 11a consists of a film of resin. The photosensitive layer 11b consists of a coating of photographic emulsion applied to one face of the support 11a. The continuous photo film 11 has a predetermined width by which raw material with a considerable width has been slitted. The continuous photo film 11 is wound about a reel 16 with the photosensitive layer 11b positioned inside, and placed in the photo film supplier unit 12. At first the continuous photo film 11 is conveyed to the perforator unit 13, in which a train of perforations are formed in the continuous photo film 11 along one edge of the continuous photo film 11. Then the continuous photo film 11 is conveyed to the side printer unit 14. The side printer unit 14 is constituted by a printer head 17 including for example a plurality of small light-emitting diodes (LED). While the continuous photo film 11 is moved past the front of the printer head 17, the printer head 17 photographically records information to edges of the continuous photo film 11, the information including a manufacturer's name, the number of available frames, a photo film type, the number of the photographic emulsion, and the like. Then the continuous photo film 11 is conveyed to the cutter unit 15, in which a cutter 18 cuts the continuous photo film 11 by a unit length into a photo filmstrip 19 with regular shapes of a leader and a trailer. Then the photo filmstrip 19 is transferred to a station for assembling parts of a photo film cassette, and is wound into a shell of the cassette. A plurality of conveying rollers 30 are disposed in the photo film manufacturing apparatus 10 for conveying the continuous photo film 11. In Figs. 2 and 3, each of the conveying rollers 30 includes a roller core 33 and flanges 34a and 34b disposed on respective ends of the roller core 33. The flanges 34a and 34b contact edges of the continuous photo film 11, and limit a movable range of the continuous photo film 11 in its width direction. Thus the continuous photo film 11 is stably conveyed, and appropriately can have a perforating position and an image recording position in the perforator unit 13 and the side printer unit 14. The roller core 33 has a central portion 33a of a relatively small diameter. Roll portions 33b and 33c have a greater diameter, and support respective edge portions of the continuous photo film 11. An area of the contact between the conveying roller 30 and the continuous photo film 11 is reduced by means of the central portion 33a, so that the possibility of degrading the continuous photo film 11 with scratches is kept the smaller. In Fig. 1A, the continuous photo film 11 further includes a magnetic recording layer 11c, which is a coating of magnetic material applied to the support 11a on the side opposite to the photosensitive layer 11b, so that the photo filmstrip can operate for storing magnetic information written thereto. There is abrasive material or polishing agent, mixed with the magnetic material, for contacting a magnetic head of an information reader/writer, to remove dust or dirt from the magnetic head. In Fig. 4, the conveying roller 30 includes a roller body 31 of metal and a hardness reinforcer layer 32 of diamond-like carbon. To produce the roller body 31, a rod of stainless steel is prepared, and cut and scraped. To form the hardness reinforcer layer 32, diamond-like carbon is deposited to a surface of the roller body 31. A region of applying the coating of the hardness reinforcer layer 32 is determined for contact with the continuous photo film 11. Of course the metal material for the roller body 31 is not limited to the stainless steel. The metal for producing the roller body 31 can be selected from such having sufficient hardness for being cut and scraped with a complicated partial shape. In view of ensuring sufficient physical intensity of the roller body 31, soft metal is preferably used. The surface of the hardness reinforcer layer 32, is polished and smoothed at least peripheral surfaces of the roll portions 33b and 33c which contact the continuous photo film 11. A smoothness between the conveying roller 30 and the continuous photo film 11 contacting each other is raised, so that abrasion of the conveying roller 30 can be avoided the more reliably. It is possible to prevent pressure fogging and scratches which would damage photographing quality of the continuous photo film 11. Experiments were conducted for the conveying roller by use of various coatings. Samples A-E of the conveying roller were produced, and subjected to a test of resistance to abrasion. For any of Samples A-E, a cylindrical rod of stainless steel was prepared, and had a diameter of 16 mm and a length of 50 mm. The rod was cut and scraped to form the roller body. A coating of hard material of plural kinds was applied to the roller body by the method of plasma thermal spraying. For evaluation of the resistance to abrasion, Samples A-E were experimentally incorporated in the photo film manufacturing apparatus, in which the continuous photo film was conveyed by each of them by a predetermined length. An amount of surface abrasion of Samples A-E was measured. Example F was also produced, which included a roller body with a coating of a hard chromium plating. The hard material used in the hardness reinforcer layer 32 of Samples A-E was as indicated below: Sample A: aluminum oxide (alumina); Sample B: aluminum oxide (alumina) and titanium oxide (titania); Sample C: chromium oxide; Sample D: tungsten carbide and cobalt; Sample E: tungsten carbide and nichrome. As a result, the conveying rollers of Samples A-E had only 1/6 as much an abraded amount of the surface as Example F in contact with the continuous photo film. Despite those effects derived from the use of the ceramics, the ceramics characteristically have a comparatively great weight. If the conveying roller with the ceramic coating is used as a free roller not being directly driven by any drive unit, an effect of inertia of rotation is so great as to cause slip of the roller. The ceramic roller has a shortcoming in likeliness in damaging the photosensitive material. According to the invention a diamond-like carbon coating is used as the hardness reinforcer layer 32 on the roller surface. To produce the roller body 31, a rod of metal is prepared, and cut and scraped. Material for producing the roller body 31 may be selected from such having sufficient hardness for being cut and scraped with a complicated partial shape. Examples of the metal for the roller body 31 include stainless steel, aluminum, or other soft metal used widely in the techniques of the rollers. The hardness reinforcer layer 32 of a diamond-like carbon coating is formed by the ion plating method and in the region contacting the continuous photo film 11. The ion plating method is to form a coating by decomposing benzene (C 6 H 6 ) in the plasma by specialized ion source. The ion plating method is characteristically useful for an article of a complicated shape, as it can form a coating in an uniform manner and with high tightness of the coating. The diamond-like carbon coating has very high hardness nearly equal to that of diamond, and has high resistance to heat, high resistance to welding, and high releasability. The diamond-like carbon coating has a very small coefficient of friction, which is 0.1-0.3 time as much as coefficients of friction of steel, super hard alloy, aluminum, glass, and ceramics. The hardness reinforcer layer 32 on the surface of the roller body 31 increases the surface hardness of the conveying roller 30, and thus increases resistance to abrasion. The hardness reinforcer layer 32 of the diamond-like carbon coating has an amorphous structure and thus has a very smooth surface. It is likely that the diamond-like carbon coating, if a surface of the roller body 31 underlying the diamond-like carbon coating is rough, has surface roughness developed due to the surface roughness of the roller body 31 itself. Accordingly the roller body 31, before forming the diamond-like carbon coating, is polished and smoothed at least in regions of peripheral surfaces of the roll portions 33b and 33c for contact with the continuous photo film 11. The diamond-like carbon coating being subsequently formed by the ion plating method, the conveying roller 30 can have the sufficiently smoothed surface. The smoothness between the conveying roller 30 and the continuous photo film 11 is increased. Abrasion of the conveying roller 30 is reduced the more reliably. It is possible to prevent pressure fogging and scratches which would damage the continuous photo film 11.

Claims: A conveying roller (30) for conveying photosensitive material (11) comprising a roller body (31) of metal, said roller body including a roller core (33), a pair of flanges (34) disposed to project from said roller core (33) in a disk manner for contacting respective edges of said photosensitive material (11) for stably conveying said photosensitive material (11) therebetween and a pair of roll portions (33b, 33c) having smooth surfaces disposed respectively near to an inner surface of said flanges (34) characterized in that : said pair of roll portions (33b, 33c) have a diameter greater than the diameter of said roller core (33) and support said photosensitive material (11) near to said edges of said photosensitive material (11), and in that a diamond-like carbon coating (32) is formed on said smooth surfaces of said roll portions (33b, 33c), and said coating being polished and smoothed at least on one roll portion (33b, 33c) contacting said photosensitive material (11). A conveying roller as defined in claim [3]1, wherein said roller body (31) further includes a pair of ring-shaped grooves each of which is formed between one of said roll portions and one of said flanges. A conveying roller as defined in one of the previous claims, wherein said metal comprises stainless steel or aluminum. A method for producing a conveying roller (30) for conveying photosensitive material (11) comprising a roller body (31), said roller body including a roller core (33), a pair of flanges (34) disposed to project from said roller core (33) in a disk manner for contacting respective edges of said photosensitive material (11) for stably conveying said photosensitive material (11) therebetween and a pair of roll portions (33b, 33c) disposed respectively near to an inner surface of said flanges (34) and having a diameter greater than the diameter of said roller core (33) for supporting said photosensitive material (11) near to said edges of said photosensitive material (11), said method comprising the steps of: a) cutting and scraping a rod material of metal into said roller body (31), b) forming a hardness reinforcer layer (32) on the surfaces of said roll portions (33b, 33c) supporting said photosensitive material (11) by ion plating of a diamond-like carbon coating, and c) polishing and smoothing the surface of at least one of said roll portions (33b, 33c) contacting said photosensitive material (11). A method as defined in claim 4, further comprising the step of smoothing said roller body (31) at least on the surfaces of said roll portions (33b, 33c).

Inventors: KUBO TAKASHI, MATSUZAWA HIDEKI, SANDA AKIHIRO, WADA MASAYOSHI, KUBO, TAKASHI, MATSUZAWA, HIDEKI, SANDA, AKIHIRO, WADA, MASAYOSHI
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1998
Main classification: B65H27
IPC codes: G03D3, B65H27