Device for intermediate storage of photographic sheet material

Photography – Fluid-treating apparatus – Having photographic medium feed

Reexamination Certificate

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Details

C271S189000, C271S264000, C226S189000, C396S615000

Reexamination Certificate

active

06190064

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to it device for the intermediate storage of photographic sheet material with an entrance for receiving the material, an exit for discharging the material, several rotatably supported rollers for transporting the material in sheet form from the entrance to the exit and a drive means for driving the rollers.
2. Description of the Related Art
The devices this type can preferably be used in a so-called minilab. In the minilab, image originals recorded on photographic film are read with the device and the obtained image information is exposed on photographic sheet material in either analog or digital form. After the exposure step, the photographic sheet material is transferred to another station for developing the exposed photographic paper. The exposed image information which is recorded as a latent image of the photographic sheet, is thereby made visible and stabilized. Fully processed paper copies with the image information are returned at the exit of the minilab. The minilab performs the exposure end developing processes automatically in sequence. Disadvantageously, however, the exposure process may occur much faster than the developing process in which the photographic sheet paper passes through chemical baths which takes time. Since the image information of a following film is read only after the photographic paper associated with the current film has been fully exposed and developed, there may be a waiting time until the next film can be processed. This reduces the efficiency of the minilab.
It was therefore proposed in the U.S. Pat. No. 4,866,47220 to arrange between the station exposing the photographic paper and the station developing the photographic paper a device for intermediate storage of the exposed photographic paper. According to U.S. Pat. No. 4,866,472, a container is placed between the exposure station and the developing station, in which container the exposed photographic sheet paper is inserted at an entrance disposed at the top of the container. An exit is provided at the underside of the container, wherein the exposed photographic paper intermediately stored in the container is transferred to the developing station over a roller. The different sheets of the photographic paper are arranged in the container in the form of stacks. With his arrangement, the sheets can be supplied and withdrawn consecutively. The sheets are processed in the exposure and developing station in the original order. Since the exposed photographic paper is stacked in the container one on top of the other and adjacent sheets make contact which each other, this conventional device may disadvantageously cause adjacent sheets to damage each other. For example, the sheets can stick to one another.
The European patent application EP 0 708 365 A1 discloses a device for the intermediate storage of photographic sheet material which obviates the aforedescribed disadvantages. In the device disclosed in this reference, the photographic sheet paper is inserted into the intermediate storage device after exposure in the exposure station and transported onward through the intermediate storage device towards the entrance of the developing station. This prevents individual sheets of photographic paper from coming into contact with each other in the intermediate storage device. Different arrangements are proposed for receiving and transporting the individual sheets in the intermediate storage device. All these arrangements have in common that the sheets are transported by a band which moves over drive rollers. The transport speed of the sheets transported through the intermediate storage device is thereby held constant. To ensure that the disclosed intermediate storage device has sufficient storage capacity for the intermediate storage of photographic sheet paper and that the transit time of a sheet to be intermediately stored is kept as short as possible, it is proposed to make the transport path of the sheets through the intermediate storage device dependent on the total number of sheets held in the intermediate storage device. Mechanical assemblies which can be used to vary the transport path of the intermediate storage device—and thereby also the storage capacity of the intermediate storage device—tend to be quite complex.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a device for the intermediate storage of photographic sheet material which has sufficient storage capacity, while at the same time ensuring that a sheet of the photographic material has a short residence time in the device.
This object is solved by that the device including a monitoring means for monitoring positions of intermediately stored sheets of the photographic material and a control means for controlling the rotation speeds of the driveable rollers, so that during operation the rotation speed of at least one of the rollers can be adjusted independently of the rotation speeds of the other rollers and dependent on the monitored positions.
According to one aspect of the invention, the rotation speed of at least one of the rollers provided in the device of the invention to transport the photographic sheet material can be adjusted depending on the positions of intermediately stored material. In this way, a high transport speed of the sheet material through the device of the invention and a correspondingly short residence time inside the device can be attained, thereby making the inventive device very efficient. Advantageously, the mechanical design is less complex which makes the device also very reliable. According to an advantageous embodiment of the invention, the separation between two driveable rollers is smaller than or equal to the length of the sheets of the photographic material to be intermediately stored. This arrangement provides a trouble-free transport of a sheet through the intermediate storage. Since the photographic material has a certain stiffness, the sheet can be easily transferred from one roller to the next.
According to another advantageous embodiment of the invention, additional rotatable rollers are arranged parallel to the driveable rollers for guiding the sheet material between such roller pair. This arrangement improves the transport of the photographic material. The additional rotatable rollers need not be themselves driveable.
Advantageously, the rotation speed of the rollers is adjusted so that a predetermined minimal separation is maintained between two consecutive sheets which are intermediately stored before the exit. This arrangement provides a certain freedom of movement and also a certain tolerance when the transport speeds is increased or decreased of during the transport of individual sheets through the device of the invention. In addition, two consecutive sheets are prevented from making contact with each other.
The positions of intermediately stored material can be easily monitored by driving the rollers with at least one stepping motor, wherein the individual steps for driving the rollers are measured and monitored. Since the steps executed by the at least one stepping motor correspond to a distance traveled by one of the intermediately stored sheets, the position of this sheet can be easily monitored in the device of the invention.
Any slippage between the rollers and the sheet when the sheet is transported between the rollers, can advantageously be recognized by a sensor. The current position of the sheet can thereby be determined more accurately, since the detected slippage during the determination of the position can be taken into account in addition to the monitored steps of the stepping motor. If the device according to the invention is advantageously arranged between an exposure station and a developing station, then—according to another advantageous embodiment—a signal can be produced and transmitted to the exposure station when the storage capacity of the storage device according to the invention has been reached. The exposure station can then advantageously adapt its

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