The present invention relates generally to the field of strip treatment equipment, and more particularly, is directed to a method and apparatus for straightening a portion of the strip relative to the remaining portion of the strip.
It is common practice to store elongate webs of strip material in coiled form for both convenience in handling, compactness in storage and for allowing the material to be played out from the roll in a regulated manner without fear of bending, twisting, crimping or other damage. Such elongate webs are commonly employed in the photographic industry and film both in undeveloped and in developed form is commonly stored in coiled or rolled condition. In the case of photographic film, both for still cameras and for motion picture cameras, film in coiled condition is by far the most popular method of storage.
In the case of the photographic industry, the film is first packed in a roll prior to use. After the rolled film has been exposed in the camera, during the picture taking process, the film is again rolled into some type of container and is then transported to a photographic developing laboratory to develop the exposed film. It has been found that due to the long period of storage of the film in rolled condition, both before exposure and after exposure, a permanent set or coil develops in the film and accordingly, even after the film is removed from its container in the darkroom, it still possesses a natural memory to curl or coil to assume the tightly rolled condition as within the container itself.
It is now common practice to employ automatic film developing equipment in the laboratories in the interest of savings, both in time and in money, during the development process. Most presently available film developing equipment comprises a plurality of juxtaposed liquid containing tanks for storing the developing, fixing and washing liquids through which the exposed film is passed prior to drying. In order to lead the film automatically through the various liquid containing tanks and the drying system, improved film propelling mechanisms have been developed which generally comprise pluralities of rollers designed to automatically lead the film through the apparatus for the complete developing process. It is necessary that the leading edge of the film be straight so that the film can follow the desired path of travel through the various rollers and guides provided to automatically propel and guide the film through the equipment.
Due to the tightly coiled nature of the film as it is applied to the developing machinery, prior workers in the art have found it desirable to provide a straight strip of material at the leading edge of the film to act as a leader to facilitate initial threading through the apparatus. In order to affix the leader to the leading edge of the film, it has been previously necessary to find some suitable method of joining the two strips together such as by employing an adhesive, plastic tape, staples, heat sealing or other mechanical means. Of course, such joining operations must be performed by hand and these operations thereby increase the cost of the developing process due to the manual handling required to affix the leader and the additional cost represented by the material of the leader itself.
Prior workers in the art have encountered difficulties when employing a separate leader in that it was necessary to spend considerable time and effort to train employees to properly affix the leader. Even with such training, due to the fact that the operations had to be performed in the dark room, sometimes the leader was not securely attached or was connected out of longitudinal alignment. Such defects often caused the leader to break or to otherwise disconnect from the film, thereby causing irreparable damage to the film being processed. The separate leaders previously universally in use created other problems in that chemicals had a tendency to collect in the overlap portion between the film and the leader. This caused increased contamination as the film was directed from tank to tank. The prior art methods further resulted in increased costs due to the time required to remove the leader following the film processing operation. When staples were employed, the staples had to be fabricated of special chemical resistant materials, all at increased cost.