Photocopying – Projection printing and copying cameras – With film severing
Reexamination Certificate
2000-01-07
2001-06-26
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
With film severing
C355S040000, C355S027000
Reexamination Certificate
active
06252646
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photosensitive material exposure apparatus, which records an image on the photsensitive material by main-scanning the image by an exposure device, while sub-scanning the photosensitive material by using an exposure drum or plurality of exposure rollers which are driven and rotated by driving force of a driving device.
2. Description of the Related Art
Conventionally, in a case in which an image is recorded on a photosensitive planographic printing plate such as a PS (presensitized) plate, exposure is carried out in a state in which a lithographic film is superposed on top of the photosensitive planographic printing plate.
An image is recorded on the lithographic film by a photosensitive material exposure apparatus which is called a ‘film setter’, and through a developing process, the image is formed.
A magazine that takes up and accommodates therein an elongated lithographic film in layers is set in this film setter.
The lithographic film that is pulled out from this magazine is wound around an exposure drum. At this time, nip rollers are disposed at two different points on the circumference of the exposure drum. The lithographic film is nipped between the nip rollers and the exposure drum. A predetermined length of the lithographic film is kept in close contact with a portion of a circumferential surface of the exposure drum. The exposure drum is rotated at a predetermined rotational speed by a driving force of a driving device, and this rotation is a sub-scanning movement. An image recording apparatus, which is an exposure device, is disposed in a radial direction of the circumferential surface of the exposure drum, at which the lithographic film is kept in close contact.
In the image recording apparatus, light beams emitted from a laser are scanned in an axial direction of the exposure drum through a plurality of optical systems (main-scanning). Accordingly, main-scanning is carried out repeatedly with the light beams while the lithographic film is sub-scanned. Because the light beams are controlled to be on/off (or duty-controlled) on the basis of image information, a predetermined image can be recorded on the lithographic film.
The lithographic film on which images have been recorded is guided to an ordinary conveying path, is discharged from the film setter, and then is fed to a developer for the next process.
In a case in which a printed material produced by using a photosensitive planographic printing plate is a color image, a photosensitive planographic printing plate must be prepared for each of four color components of C (cyan), M (magenta), Y (yellow), and K (black) with respect to each image (i.e., four photosensitive planographic printing plates).
In positioning these four photosensitive planographic printing plates relatively with each other, a main-scanning starting line on the lithographic film must be positioned accurately. For this reason, holes for positioning these four photosensitive planographic printing plates are punched previously in the lithographic film such that the lithographic film and each of the photosensitive planographic printing plates are superposed relatively to each other on the basis of these punched holes.
In recent years, there has been provided a photosensitive material exposure apparatus which records an image directly on the photosensitive planographic printing plates by using an exposure device. In this case, holes for positioning these photosensitive planographic printing plates to allow the plates to be wound accurately around a printer drum must be punched. When the image is printed, each of the photosensitive planographic printing plates is wound around the printer drum on the basis of the holes punched in the four photosensitive planographic printing plates.
A punching unit for punching these holes is built into the film setter.
However, if the photosensitive material is slackened inside the photosensitive material exposure apparatus during the conveyance thereof, the punched holes and the main-scanning starting line on the photosensitive material may displace from each other by an amount corresponding to the slack. Therefore, in order to have a hole-punching position and a main-scanning starting line position correspond relatively to each other on the photosensitive material in the photosensitive material exposure apparatus, a complicated positioning control becomes necessary.
SUMMARY OF THE INVENTION
In view of the aforementioned facts, it is an object of the present invention to obtain an exposure apparatus for a photosensitive material (for example, a lithographic filmm or a photosensitive planographic printing plate) having a simple structure through which both a main-scanning starting line position and a hole-punching position on the photosensitive material can correspond relatively to each other.
In accordance with a first aspect of the present invention, there is provided a photosensitive material exposure apparatus which records an image on a photosensitive material by main-scanning the film by an exposure device while sub-scanning the photosensitive material by either an exposure drum or a plurality of exposure rollers which is driven and rotated by driving force of a driving device, comprising: a punching unit which is provided along a second path disposed at a downstream side of the exposure drum or the exposure rollers and branching from a first path leading to a latter process, and which punches holes at a leading edge portion of the photosensitive material; a punching controller which is provided at the second path, which has a sensor for detecting the leading edge portion of the photosensitive material, and which controls punching of the punching unit; a positioning controller which positions a main-scanning starting line, which is spaced apart from a hole-punched portion of the photosensitive material at a fixed distance, on the photosensitive material, at an image recording starting position of either the exposure drum or the exposure rollers by conveying the photosensitive material back by reverse rotation of either the exposure drum or the exposure rollers after the holes are punched by the punching controller, and by measuring with an encoder an amount of the photosensitive material conveyed back; a guiding controller which, when it is necessary to punch holes at the leading edge portion of the photosensitive material, guides the photosensitive material to the second path by having the photosensitive material pass without an image recorded thereon at an image recording position of either the exposure drum or the exposure rollers; and an encoder connected to the drum and the positioning controller, the encoder providing a signal for the positioning controller to determine when either the drum or the rollers has rotated the predetermined amount
According to the present invention, preferably, the blade is remained in the inserted state for a predetermined period of time after the exposure drum or a set of the exposure rollers is rotated backwards and the positioning controller resets the encoder each time before the blade moves to the retracted state.
According to the present invention, preferably, a driving torque of the exposure drum or the set of exposure rollers is made to be lower than that during normal rotation thereof so as to prevent tension higher than the predetermined threshold from being applied to the photosensitive material.
The photosensitive material passes through a first path and is then discharged therefrom, and thereafter conveyed to a developer for the subsequent process.
In a case in which an image recording mode is for a color image, image recording of the photosensitive material must be performed for each of C, M, Y, and K color components, and holes must be punched in these photosensitive materials for positioning these films relatively to each other.
In this case, the photosensitive material is passed through a first path without recording an image at the image recording position on the exposur
Adams Russell
Fuji Photo Film Co. , Ltd.
Nguyen Hung Henry
Sughrue Mion Zinn Macpeak & Seas, PLLC
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