Photo film cassette

Winding – tensioning – or guiding – Unwinding and rewinding a machine convertible information... – Cartridge system

Reexamination Certificate

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Details

C242S610600, C242S614000, C396S512000, C396S516000

Reexamination Certificate

active

06216971

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photo film cassette. More particularly, the present invention relates to a photo film cassette of a type in which rotation of a spool advances a leader of photo film to the outside, and which includes improved flanges of the spool.
2. Description Related to the Prior Art
There are various documents U.S. Pat. No. 5,296,887, JP-A 2-18545 (corresponding to U.S. Pat. No. 4,848,693) and JP-A 4-320258 (corresponding to U.S. Ser. No. 655,944) which suggest a photo film cassette in which a cassette shell consists of molded parts of resin, and rotation of a spool core causes a leader of photo film to advance to the outside of the cassette shell. U.S. Pat. No. 5,083,155 (corresponding to JP-A 3-179341) suggests a container for containing developed photo film, the container including the cassette shell of the same structure for the purpose of facilitating handling and preservation of the developed photo film.
The photo film cassette includes a pair of flanges, which are disposed on respective axial ends of the spool core. There are circumferential lips formed on the respective periphery of the spool flanges to transmit rotation of the spool core reliably to the roll of the photo film. The circumferential lips partially wrap lateral edges of the outermost turn of the photo film to prevent the photo film from being loosened. In the course of advance and rewinding of the photo film, rigidity of the photo film causes the spool flanges to flex. Therefore the circumferential lips squeeze the lateral edges of the photo film between them.
In the course of advance of the photo film, the spool flanges must be spread by the photo film in the vicinity of the photo film passageway, in order to release the photo film from being partially wrapped by the circumferential lips. The spool flanges rotate always with deformation, and thus are originally formed with a small thickness. On the other hand, the spool flanges require sufficient rigidity, resistance to abrasion and other conditioned characteristics. Typically the circumferential lips must have considerable rigidity and resistance to abrasion for the reason of frictional contact with the lateral edges of the photo film in the course of the advance and rewinding of the photo film.
To provide the spool flanges with sufficient rigidity and resistance to abrasion, appropriate material for forming the spool flanges should be selected. Also an appropriate molding method for the spool flanges must be used. For example, documents such as U.S. Pat. No. 5,211,348 (corresponding to JP-A 4-251841), JP-A 6-148808 and U.S. Ser. No. 531,966 (corresponding to JP-A 8-146562) suggest a flange forming method. A polyethylene resin sheet is formed by extrusion with a thickness of 0.3 mm, and then heated and softened. Flange-shaped portions are formed by vacuum forming or pressure forming of the resin sheet, and then punched to obtain the spool flanges.
No matter whether good the material is to be used for the spool flanges in view of the rigidity and resistance to abrasion, the edge of the circumferential lips of the spool flanges of the prior art, having a rounded shape, still contacts the lateral edges of the photo film frictionally at one point. There remains possibility in rubbing the circumferential lips to create scraped powder or dust.
When the scraped powder or dust is created inside a camera, it is likely to be stuck on the photo film in exposure regions to lower photographic quality. The photo film according to the IX 240 type (Advanced Photo System, trade mark) is also provided with magnetic recording layer. The scraped powder or dust in the camera is likely to deposit on a magnetic head to cause failure in properly writing data to, or reading data from, the magnetic recording layer.
SUMMARY OF THE INVENTION
In view of the foregoing problems, an object of the present invention is to provide a photo film cassette of a type in which rotation of a spool advances a leader of photo film to the outside, and in which the circumferential lips of the spool flanges are prevented from being frictionally rubbed by the photo film.
Another object of the present invention is to provide a photo film cassette having flanges of which supply and conveyance are prevented from being influenced by occurrence of electrostatic charge between flanges, and between a flange and a part feeder which conveys the flange.
Still another object of the present invention is to provide a photo film cassette of which flanges can be molded consecutively one after another at remarkably higher speed.
In order to achieve the above and other objects and advantages of this invention, a photo film cassette includes a spool core about which photo film is wound in a form of a roll, a cassette shell for containing the spool core in a rotatable manner, first and second flanges, having a disk shape, and secured to respective ends of the spool core, for regulating lateral edges of the roll of the photo film, a circumferential lip, disposed at least on the first flange, extended toward the second flange, for wrapping one of the lateral edges of an outermost turn of the photo film of the roll, to prevent the photo film from being loosened. A rim portion is disposed on an circular edge of the circumferential lip confronted with the second flange, to project with a bend away from the spool core. A contact face is disposed on the rim portion, for contacting the one of the lateral edges of the photo film when the photo film is unwound from the spool core or wound back about the spool core, the contact face having a contact range of 0.15-0.8 mm in contacting the one of the lateral edges of the photo film.
In a preferred embodiment, the contact face is inclined away from the spool core in a projecting direction of the rim portion, for reducing resistance of the circumferential lip against the photo film when the photo film is unwound from the spool core or wound back about the spool core.
The contact face is an at least partially conical surface.
The contact range is obtained by drawing the photo film out of the cassette shell for inspection, embedding an inside of the cassette shell with test resin, hardening the test resin, further drawing the photo film out of the cassette shell, polishing the test resin, and when a surface of the photo film appears by polishing the test resin, measuring a range where the photo film appears.
Furthermore, a photo film passageway is formed in the cassette shell, and adapted to advance and rewinding of the photo film therethrough. A separator claw is disposed in the cassette shell, for separating the outermost turn of the photo film from the roll when the spool core is rotated in an unwinding direction while an entirety of the photo film is contained in the cassette shell, to direct the outermost turn to the photo film passageway.
Consequently the circumferential lips of the spool flanges are prevented from being frictionally rubbed by the photo film.
In another preferred embodiment, the first and/or second flange includes one bottom face being substantially flat. At least one support projection, disposed to project from the bottom face, directed downwards when conveyed and supplied, for supporting the bottom face, to reduce an area where the bottom face is contacted externally.
The bottom face is positioned opposite to the roll of the photo film.
The first and/or second flange is formed from resin, has a weight of 0.5 gram or less, and has an average thickness of 0.4 mm or less.
The at least one support projection is semi-spherical or conical.
Consequently supply and conveyance of flanges are prevented from being influenced by occurrence of electrostatic charge between flanges, as the contacting area is reduced.
In a further preferred embodiment, the circumferential lip has an inner surface confronted with the roll of the photo film. At least one ridge is disposed to project from the inner surface.
The circumferential lip further has an outer surface positioned opposite to the roll of the photo

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