DE69119458T2 - Treatment device with speed-independent fixed film distances - Google Patents

Description

The invention relates generally to apparatus for processing film and similar photosensitive material, and more particularly to a processor having means for varying the transport speed and means for maintaining a fixed film pitch independent of the transport speed. Photosensitive material processors such as the Kodak X-OMAT processors are used with utility in applications such as the automatic processing of X-ray films for medical imaging purposes. The processors automatically transport webs or sheets of photosensitive film, paper or the like (hereinafter referred to as "film") from an input location along the film transport path through a series of chemical processing tanks in which the material is developed, fixed and washed, and then through a drying station to an output or receiving location. The processor typically has a film path of fixed length, so the final image quality depends on several factors, including the transport speed, which determines the length of time the film strip is in the solution, and the temperature and composition of the processing chemicals (called the processing "chemistry").

In a typical automatic processor of the type underlying this invention, the film transport speed is set at a constant value and the chemistry is determined according to a preset recommended temperature, for example 34ºC (93º F), with a prescribed tolerance range of +/- XºC (XºF). A temperature control system included in the processor maintains the chemicals within the range so determined.

Conventional processing devices typically have a film width sensor in the form of a reflection sensor arranged adjacent to a material inlet opening. Infrared sensor arrangement and may also contain an entry detector in the form of a Hall effect switch or the like, which detects the separation of the entry rollers as the film sheets pass the front end of the transport path. The film width sensor not only indicates the width of a film sheet entering the processing device, but can also indicate the passage of the leading and trailing edges of the individual film sheets, since the signals from the film width sensor change considerably as a leading or trailing edge passes. The information on the occurrence of the leading and trailing edges and on the film width is used in conjunction with the known constant transport speed to monitor the cumulative total film surface processed as a guide for controlling the regeneration of the chemicals. A separate entry roll detector signals that a film sheet has actually entered the nip of the first pair of rollers and is not just lying motionless on the film guide below the width sensor.

When sheets of film are fed sequentially into a processor, it is desirable that a gap be maintained between the trailing edge of a first sheet and the leading edge of the next sheet so that the sheets do not overlap. The gap should be large enough to prevent overlap even if one or both of the sheets of film should slip or skew along the transport path, but not so large as to unduly increase the processing time. For a given processor with a constant fixed transport speed, the film gap can be controlled by establishing a fixed time interval between the trailing edge of the first sheet of film entering the processor and the time at which the user is prompted to insert the next sheet. When the leading edge of the first sheet is detected entering the processor, an indicator in the form of a "WAIT" light will illuminate to signal that the required gap has not yet been reached. At a predetermined time after the trailing edge has been detected entering the processing device, the "WAIT" indicator light goes out and a "READY" indicator light comes on.

Although conventional processing equipment for processing X-ray films is usually designed to operate at a constant film transport speed; however, modifications by changing gears and the like are possible to change the process. In addition, new processing machines are now coming onto the market which can operate in several modes. The modes are often referred to briefly by the nominal total film transport time, which can be defined as the time from the entry of the leading edge of a sheet of film at the material inlet point to the exit of the trailing edge of the same sheet of film at the exit end. Conventional processing machines operate in "Normal" (90 seconds), "Fast" (45 seconds) or "Quick" (30 seconds) modes and can also be modified to operate in an extended cycle, as described, for example, in L. Taber & AG Hans "Processing of Mammographic Films Technical and Clinical Gonsideration", Radiologv, Volume 173, No.1, pp. 65-69, October 1989. In this latter mode, the processing speed is reduced and the chemical temperature is increased in order to increase the image contrast and to better identify density changes in the connective tissue. The new processing devices are adjustable in terms of run parameters, including the transport speed, in order to be able to use the same processing device for several processing modes.

In processing devices with selectable transport speed, it is desirable to be able to maintain a fixed film sheet distance during transport, regardless of the set transport speed.

Conventional systems in which the film sheet spacing is determined by a fixed time interval are not suitable for this. This is because if faster transport speeds are selected, the same fixed time interval results in a sheet spacing that is too large. At lower transport speeds, the same time interval results in a sheet spacing that is too small.

In a known arrangement described in US-A-4,300,828, the sheet spacing is determined by means of a feed counter which is timed by a drive shaft encoder. The feed counter is loaded by a microcomputer with a count which corresponds to the number of shaft encoder pulses required to transport the leading edge of the sheet past a certain point on the transport path. When the counter reaches zero, a feed indicator is activated and the "WAIT" indicator light goes out. A keyboard and push buttons as well as a display are used to enter control data such as regeneration rates, transport speeds, temperatures and the like.

One object of the invention is to provide a system for changing the set time in a processing device operating with a fixed time interval between the trailing edge of a first sheet and the leading edge of a second sheet as a function of changes in the transport speed, so that a fixed film sheet interval is maintained and overlapping of the film sheets is excluded, regardless of the transport speed.

Another object of the invention is to provide an illuminated indicator that signals the achievement of the recommended film sheet spacing in an automatic processing device that can operate with a variety of transport speed settings.

According to the invention defined in claims 1 and 8, a photosensitive material processing apparatus comprises means for automatically transporting the material along a path through developing, fixing, washing and drying stations and means for monitoring the entry of the trailing edge of a particular material into the processing apparatus and further means for setting system parameters controllable by user input, including a desired transport speed, and means for detecting and signaling the passage of time from the entry of the trailing edge to the time at which the next sheet can be fed at a desired, fixed optimum distance.

According to one aspect of the invention, which will be explained in more detail below, the film transport speed of the processor is set by the selection of a mode of operation by the user, and the indicators in the form of the "READY" and "WAIT" indicator lights are controlled according to a certain lead time required to ensure the maintenance of a desired linear distance between successive film sheets in that particular mode of operation of the processor. A microcomputer determines the number of counting pulses with which a counter is to be loaded depending on the set transport speed.

The invention is explained in more detail below using an embodiment shown in the drawing.

Show it:

Fig. 1 is a perspective view of a processing device in which a system according to the invention for determining the film sheet spacing can be used

Fig. 2 is a schematic representation of the relevant elements of the processing device according to Fig. 1;

Fig. 3 is a detailed view of an infeed roller detector that can be used in the processing device according to Figs. 1 and 2;

Fig. 4 is a block diagram of the system for determining the film distance used in the processing device according to Figs. 1 and 2; and

Fig. 5 is a flow chart of the operation of the system of Fig. 4.

In all drawings, identical elements are designated by identical reference numerals.

The principles of the invention are illustrated, by way of example, with reference to a system 10 for establishing a fixed film spacing (Fig. 4) for use in a processing device 12 (Figs. 1 and 2) for automatically processing light-sensitive material in the form of successive film sheets F1, F2 (Fig. 2), for example for the development of X-ray films for medical diagnostic purposes.

The processing device 12 has a feed compartment 14 arranged in front of a material inlet opening 15 (Fig. 2). The front of the processing device 12, including the feed compartment 14 and the material inlet opening 15 are located in a darkroom to avoid undesired exposure of the film sheets F1, F2 to be fed to the processing device 12. The remaining part of the processing device 12 can be located outside the darkroom. The sheets F1, F2 entering through the material inlet opening 15 are transported along a path 16 (indicated by arrows) through the processing device 12 and finally ejected at the rear of the processing device 12 into a collecting container 17 at the outlet opening 18.

The processing device 12 includes a development station comprising a tank 21 filled with development chemicals, a fixing station comprising a tank 22 filled with fixing chemicals, and a washing station comprising a tank 23 filled with wash water or other suitable film washing device. In addition, the processing device 12 includes a drying station 24 with a plurality of oppositely arranged air jet nozzles 25 or other suitable film drying device.

Near the opening 15 there is a sensor 26, for example a conventional universal film detector card, a reflective infrared sensor arrangement which, when a sheet F1, F2 appears at the entry opening 15, provides signals representing the sheet width. The film width sensor 26 also indicates the passing of the leading edge and the trailing edge of the individual sheets at the point 26 of the processing device 12. Furthermore, a second sensor 27 in the form of a reed magnetic switch 29 or the like (Fig. 3) can be provided which detects the separation of the infeed rollers 28 and signals the start of the transport of a film sheet along the path 16. In the arrangement shown, the sensor 27 is a Hall effect sensor with an actuating or attachment element 32, which sits on a rocker arm and can be pivoted about a pivot pin 37 from the fully marked position to the position shown in dashed lines depending on the separation of the upper inlet roller 28a from the lower inlet roller 28b. In addition, further sensors can be provided.

In Fig. 2, the film path 16 is defined by a plurality of film transport rollers 30 and a plurality of guide shoes 31 which are arranged such that they Guide film sheet F in sequence through the tanks 21, 22, 23 and the drying device 24. The rollers 30 form the transport system for transporting the sheets F1, F2 through the processing device 12. Transfer groups are provided at the interfaces between the respective tanks 21, 22, 23 and the drying device 24, which transfer the sheets from one station to the other. The rollers 30 can be driven in a conventional manner via a common drive shaft 33 (Fig. 4), which drives adjacent rows of rollers 30 at the same speed but in opposite directions via right-hand and left-hand screws arranged alternately at an axial distance from one another, so that the sheets F1, F2 are transported in the direction of the arrows along the movement path 16. The drive shaft 33 can be driven by an electric motor 34, for example a brushless DC motor with variable speed, via a slip-free chain drive and toothed disks (not shown).

The temperature of the developing chemicals in the tank 21 can be controlled by a pumping line 35 (Fig. 2) which has a pump P by means of which the developing liquid is pumped out of the tank 21, through a heating shaft or other suitable heating device and a filter and then back into the tank 21. A temperature sensor 37 (Fig. 4) is provided in the tank 21 or in the pumping line 35 to monitor the temperature of the developer. The temperature of the developer can also be displayed by a measuring device 41 arranged on an external control panel 42 of the processor 12. The temperature control of the fixing liquid can be controlled in a suitable manner by passing a loop 39 submerged through the fixing tank 22.

Fig. 4 shows a control system that can be used for an embodiment of the invention. As can be seen from Fig. 4, a microcomputer 43 is provided to control the operation of the processing device 12. The microcomputer 43 receives manual input from the user via a mode switch 44 as to which processing mode is desired. The system can be designed so that the user has the choice between predetermined modes of operation, for example Normal, Fast, "Kwik", or extended modes of operation with predetermined associated parameters regarding film speed and chemistry temperature; furthermore, the System may be designed so that the user can directly enter a desired set of parameters relating to film speed and temperature. One embodiment of a mode switch 44 consists of an alphanumeric keypad 45 and a keypad display 46 (Fig. 1) which enable communication between the user and the microcomputer 43 for programming. For example, a function code may be entered to signal that a mode of operation is to be selected, followed by a selection code to designate the selected mode of operation. Alternatively, a function code for film speed or chemistry temperature may be entered, followed by entry of the selected speed or temperature settings. Another possible embodiment of the switch 44 is to provide a plurality of push buttons or toggle switches, each associated with a selectable mode of operation, which can be selectively operated by the user according to his needs.

The microprocessor 43 also receives input information from the film width sensor 26, the material entry roller sensor 27, the temperature sensor 37 for the developing liquid and optionally also from a shaft speed sensor 48. The shaft speed sensor 48, which can have a shaft pulse generator connected in a rotationally fixed manner to the drive shaft 33 and an associated pulse sensor, provides feedback data on the speed of the common shaft 33 which drives the transport rollers 30 uniformly (Fig. 2). This results in the speed at which the film is moved along the film transport path 16. The width sensor 26 supplies the microcomputer 43 with data on the passage of the leading and trailing edges and the width of the film sheets F1, F2. This data, together with the film speed provided by the sensor 48, can be used to obtain cumulative data on the total film area developed for controlling the replenishment of the chemicals. The infeed roller sensor 27 signals the entry of the leading edge of a film sheet into the roller conveyor 16 or the passage of a trailing edge at a particular point on the conveyor 16. This information, together with the film speed and the known length of the total conveyor 16 from the infeed rollers 28 to the exit rollers 50 (Fig. 2), can be used as an indication of when a film sheet is present along the conveyor 16.

The microcomputer 43 is connected in Fig. 4 to the motor control circuit 51, the heater control circuit 52 and the warning signal control circuit 53. The motor control circuit 51 connected to the motor 34 controls the speed of rotation of the drive shaft 33. This in turn controls the transport speed of the film sheets F1, F2 along the film path 16 and thus determines the length of time a film sheet stays in each of the stations (and thus controls the development time). The heater control circuit 52 controls the temperature of the developer flowing through the circulation path 35 (Fig. 2) and thus the temperature of the developer in the tank 21 and the fixer in the tank 22. The warning display control circuit 53 connected to the warning indicators in the form of warning lamps "WAIT" 54 and "READY" 55 controls the switch-on and switch-off times of these lamps. Corresponding warning lamps "WAIT" 54 and "READY" 55 (e.g. LEDs) can be provided both on the (not shown) darkroom side and on the normal light side (see control panel 42 in Fig. 1) of the development device 12.

According to the invention, as shown in the flow chart in Fig. 5, a user-desired mode change is entered (100) into the microcomputer 43 via the keyboard 45 (Fig. 1) or other mode switch 44 (Fig. 4), which determines (102) (using a look-up table, algorithm, or the like) the reference developer temperature and reference transport speed parameters recommended for the selected mode. The motor and heater control circuits 51, 52 are then instructed to control the motor and heater to adjust the actual developer temperature and actual film transport speed in accordance with the determined reference temperature and reference speed. If desired, the system can be configured to allow a specific film transport speed to be entered directly. The selection of a new film transport speed, whether by selecting a different operating mode or by direct input, results in the determination of the new time interval between the trailing edge of a first sheet F1 and the leading edge of a second sheet F2, which is required to achieve a predetermined desired fixed sheet spacing (103,104).

The required time interval in seconds between the trailing edge of a first sheet F1 and the leading edge of a second sheet F2 can be determined, for example, using the following algorithm:

Time (s) ((LN) x 60 s/min)/1 00,

where L is the film distance in cm (inches) x 100 and V is the film speed in cm/min (inches/min)

For a desired linear sheet spacing of 7.62 cm (3 inches), the following time intervals are required to maintain a constant linear spacing between the sheets F1, F2 along the transport path 16 at different transport speeds:

The time intervals can also be determined using a previously created transformation table.

When the sensors 26 and/or 27 detect the passage of a leading edge of a first sheet F1 into the processing device 12 (105), the display control circuit 53 is instructed by the microprocessor 43 to switch on the "WAIT" indicator 54 and switch off the "READY" indicator 55 (106). When the trailing edge of the sheet F1 is detected (107), the microcomputer 43 causes a counter 60 (Fig. 4) to be loaded with a count corresponding to the number of pulses of a system clock 61 required to obtain the required time interval in seconds depending on the selected transport speed (108). When the When counter 60 reaches zero (109,110), the "WAIT" indicator light goes out and the "READY" indicator light comes on (111). This indicates to the user that sheet F1 has passed a point where the next sheet F2 can be fed into the processing device.

If the counter 60 is not at zero, the "WAIT" indicator light 54 remains on and the "READY" indicator light 55 remains off (109) as shown in Fig. 5. When the counter 60 reaches zero, the "WAIT" indicator light 54 is then turned off and the "READY" indicator light 55 is turned on (111).

In addition, further warning indicators, such as a buzzer 58, can be connected to the microcomputer 43, which are activated whenever the counter 60 reaches the count zero, in order to indicate that the device is "READY" and a new sheet F can be fed into the inlet 15 (112) (112).

It will be apparent to those skilled in the art to which the invention relates that the described embodiments of the invention may be modified or replaced by others without departing from the scope of the invention as defined by the following claims.

Claims (13)

1. Device for processing light-sensitive material with - means (30, 33, 34) for automatically transporting the material from an input point along a path through developing, fixing, washing and drying stations (21, 22, 23, 24) according to a fixed transport speed; - means (43, 44) for setting a selected transport speed; - means (26 or 27) for monitoring the passage of the trailing edge of a specific material through the input point; and - an indicator light (54, 55 or 58) that signals a "READY" condition to indicate when additional material can be fed into the feed location and fed along the path after the trailing edge has traveled a predetermined distance along the path; marked by - a timer (60, 61) with a system clock (61) for generating pulses and a counter (60) connected to the system clock for counting the pulses; - means (43) dependent on the setting means (43, 44) and the monitoring means (26, 27) for automatically setting a number of pulses to be counted by the counter, the number corresponding to the time in seconds required for the trailing edge to travel a predetermined, fixed distance along the track at the said transport speed; and - means (43, 53) responsive to the counting of the number of pulses by the counter for controlling the indicator light to signal the "READY" condition as soon as the trailing edge has advanced the same predetermined fixed distance along the path. 2. Device according to claim 1, characterized in that the transport means comprise a plurality of transport rollers (30), a motor (34) for driving the rollers, a microprocessor circuit (43, 51) connected to the motor, the timer and the setting means for controlling the motor and the timer according to the optionally set transport speed. 3. Device according to claim 2, characterized in that the indicator light has at least one control lamp (54 or 55). 4. Device according to claim 1 or 2, characterized in that the device is operated at a specific one of a plurality of predetermined transport speeds, each of which corresponds to a plurality of operating modes, the setting means comprising means for selecting one of the operating modes and programming the microprocessor circuit in accordance with the selected operating mode in order to control the timer and motor in accordance with the specific one of the plurality of transport speeds which corresponds to the selected operating mode. 5. Device according to claim 4, characterized in that the means for selecting one of the operating modes comprise an operating mode switch (44) and means (45, 46) which give the user the possibility of manual input by means of the operating mode switch. 6. Device according to claim 5, characterized in that the means for manual input comprise a keyboard (45) to be operated by the user. 7. Device according to claim 2 or 4, characterized in that the means (43) for automatically setting the number comprise a transformation table which can be addressed by the microprocessor in order to set the number as a function of the different transport speeds. 8. A method for automatically setting a distance between sheets of exposed photosensitive material which is fed along a path through developing, Fixing, washing and drying stations (21, 22, 23, 24) of a processor having the following components: - means (30, 33, 34) including a motor for automatically transporting successive sheets from an input location along the path according to a predetermined transport speed; - means (26 or 27) for detecting the passage of an edge of a first sheet at the input location; - a timer (60, 61) including a system clock (61) for generating pulses; and - an indicator light (54, 55 or 58); the method comprising the following steps: - setting a transport speed depending on the selection of one of several operating modes (100,102) by the user; - Controlling the motor according to the set transport speed (102); - detecting the passage of the edge of the first sheet at the input point by the scanning means (107); - setting a number of pulses to be counted by the counter (60) as a function of the detection of the edge of the first sheet by the system clock (61) of the timer (60, 61), the number corresponding to the time in seconds that the edge moving at the set transport speed requires to travel a predetermined, set minimum distance; - counting the pulses by the counter and generating a timing signal when the number is reached; and - Activation of the indicator light depending on the timing signal (111 or 112). 9. Method according to claim 8, characterized in that the indicator light is a "WAIT" indicator light (54), the scanning means detect the trailing edge (107), and the control lamp is switched on at least when the trailing edge of the first sheet passes the input point (106), and remains switched on until the trailing edge of the first sheet has moved past the input point by the predetermined, fixed distance (111). 10. Method according to claim 8, characterized in that the indicator light is a "READY" indicator light (55), the scanning means detect the trailing edge (107), and the indicator light is switched off at least when the trailing edge of the first sheet passes the input point (106), and remains switched off until the trailing edge of the first sheet has moved past the input point by the predetermined, fixed distance (111). 11. The method of claim 8, characterized in that the detecting step comprises detecting the passage of the trailing edge (107). 12. Method according to claim 8 or 11, characterized in that the determining, controlling, fixing and actuating steps are carried out at least partially by a microprocessor (43). 13. Method according to claim 12, characterized in that the number is set via the microprocessor by addressing a transformation table in accordance with the specified transport speed.