[0001] Having exposed any kind of photographic film, including conventional photographic
film, X-ray film, graphic arts film, etc., it is necessary to pass the film through
a chemical process in order to produce the final visible image.
[0002] If this image is to be of consistent and acceptable quality, then it is essential
that regular checks are kept on the various component stages forming a film processing.
[0003] Hitherto, it has been necessary to stop the routine flow of work to carry out these
checks. With the use of automatic film processing equipment, the task becomes more
complex, requiring additionally a knowledge of the equipment.
[0004] For example, the majority of X-ray films are currently passed through automatic film
processing equipment in order to produce the final diagnostic radiograph. To assist
in correct diagnosis, the radiographs must be of the highest consistent quality. Therefore,
quality control of the film passing through the processing equipment is vital. The
method of carrying out these checks is to stop the flow of work, which in medical
radiography results in the hold-up of patient examinations, in order that the operator
may open up the processing equipment and carry out tests. This is time consuming as
well as requiring an understanding of the working of the equipment.
[0005] According to the present invention, there is provided a device for use in monitoring
parameters during the processing of a film, comprising:-
a) means for receiving input signals dependent on the values of the said parameters
from sensing means which are responsive to the parameters;
b) means for processing the said signals;
c) display means coupled with the said processing means; and
d) selection means coupled with the said processing means for enabling the values
of the said parameters to be displayed selectively by the display means.
[0006] The present invention will now be described, by way of example, with reference to
the accompanying drawings, in which:
Figure 1 is a block diagram of an example of a device according to the invention coupled
to various sensing means; and
Figure 2 shows a keypad of the device.
[0007] Referring to Figure 1, a distribution circuit board 1 is disposed in use in X-ray
film processing equipment. The distribution circuit board 1 carries power supply circuitry
2 which is fed from an alternating current supply and provides +12 volts and -5 volts
power supples. Reference numeral 3 denotes a main circuit board in a hand-held monitoring
device. The main circuit board 3 is connected to the distribution circuit board 1
via a 20-way ribbon cable, the latter providing for four digital inputs as schematically
denoted by single line 4, eight analogue inputs as schematically denoted by single
line 5 and power lines as schematically denoted by single line 6.
[0008] Installed within the processing equipment are a probe 7 for monitoring the pH value
of the developer, a probe 8 responsive to the pH value of the fixer (the probes 7
and 8 producing voltage outputs), a sensor 9 responsive to the temperature of the
developer, a sensor 10 responsive to the equipment's front dryer temperature, a sensor
11 responsive to the equipment's rear dryer temperature (the sensors 9, 10 and 11
producing current outputs), a sensor 12 responsive to the flow rate of the developer
and a sensor 13 responsive to the flow rate of the fixer (the sensors 12 and 13 producing
digital, pulse outputs).
[0009] The outputs of the probes 7 and 8 are connected via high impedance amplifiers 14
and 15 on the distribution circuit board 1 to respective ones of the eight analogue
inputs to the main circuit board 3. The outputs of sensors 9, 10 and 11 are connected
via the distribution circuit board 1 to respective ones of three others of the analogue
inputs to the main circuit board 3. The outputs of sensors 12 and 13 are connected
via the distribution circuit board 1 to respective ones of the digital inputs to the
main circuit board 3. The distribution circuit board 1 (which acts as interface means
between sensing means and the hand-held device) has, in fact, eight inputs for receiving
outputs from analogue sensing means, in the present example five of them being used
and the other three (not shown) being spare. Also, the distribution circuit board
1 has four inputs for receiving outputs from digital sensing means, in the present
example two of them being used and the other two (not shown) being spare.
[0010] The will now be described the circuitry carried on the main circuit board 3. Fed
from the +12 volts power supply from circuitry 2 are a regulator 16 for providing
+5 volts operating power for digital circuitry on the board 3 and a device 17 for
providing a +5 volts reference voltage for operating signal conditioning circuitry
18 and an analogue to digital converter 19 on the board 3. The signal conditioning
circuitry 18 is adapted for handling eight analogue and four digital channels and
the analogue to digital converter 19 is an 8-channel, 8-bit analogue to digital converter
with an integral 8-channel analogue multiplexer. The +5 volts operating power is also
fed back on one of the power lines 6 via the 20-way ribbon cable for operation of
the sensors 12 and 13 and as one of the operating voltages for amplifiers 14 and 15
(the -5 volts from circuitry 2 being the other voltage for these amplifiers). Also,
the +12 volts from circuitry 2 is used for operation of sensors 9, 10 and 11, the
probes 7 and 8 being passive probes.
[0011] The eight analogue inputs and the four digital inputs of the 20-way ribbon cable
are connected to respective inputs of the signal conditioning circuitry 18. As regards
the voltage outputs from probes 7 and 8, circuitry 18 subjects them to amplification
with a gain of one and subsequent filtering; as regards the current outputs from sensors
9, 10 and 11 it subjects them to current to voltage conversion together with an offset
to compensate for ambient temperature followed by filtering; and as regards the digital
outputs from sensors 12 and 13, it subjects them to the operation of pull-up resistors
followed by filtering.
[0012] The five analogue signals are passed from circuitry 18 via respective lines of an
eight line bus 20 to the converter 19. The main circuit board 3 further carries a
4-channel counter/timer 21 and parallel input/output circuitry 22, the two digital
signals applied to circuitry 18 being passed to counter/timer circuitry 21 via respective
lines of four lines bus 23, the other two lines of which are connected as spare lines
to respective input pins of the parallel input/output circuitry 22 for providing an
option for dealing with other functions.
[0013] The main circuit board 3 further carries a CMOSZ80 central processing unit (CPU)
24 running under the control of a 2 MHz clock 25, an address decoder 26, a 2 kB static
random access memory (RAM) 27 and a 16 kB erasable programmable read-only memory (EPROM)
28, the latter storing the necessary operating program. The output signals of the
converter 19 and counter/timer 21 are stored in the RAM 27 via a processor bus 29,
under the control of the processing unit 24, address decoder 26 and parallel input/output
circuitry 22. The converter 19 scans its inputs sequentially and provides an indication
on a line 30 to the parallel input/output circuitry 22 each time it finishes a particular
analogue to digital conversion. The result is that there is stored in the RAM 27 signals
related to: the pH of the developer; the pH of the fixer; the temperature of the developer;
dryer temperature (obtained by taking the average of the results from the front dryer
temperature sensor 10 and the rear dryer temperature sensor 11); the amount of developer
which has flowed (obtained by counting pulses from sensor 12 for a specific period);
and the amount of fixer which has flowed (obtained by counting pulses from the sensor
17 for the specific period).
[0014] The hand-held device further has a display board 31 for displaying the values of
the foregoing parameters. More particularly, the display board 31 has: three 7-segment
light emissive diode (LED) displays 32, 33 and 34 and three LEDs 32a, 33a, and 34a
before respective ones of displays 32, 33 and 34 for indicting a decimal point when
energised. Also, the display board 31 has three LEDs 35, 36 and 37 with legends alongside
them as shown; and three LEDs 38, 39 and 40 with legends alongside them as shown.
The LEDs of board 31 are energised via respective ones of display latches in block
41 via processor bus 29. For selectively displaying the value one of the forgoing
parameters, the hand-held device also has a manually operable 4 x 3 keypad 42 having
keys numbered or marked as shown in Figure 2, with the upper row having the legend
DEV. (i.e. developer) alongside it, the second row down having the legend FIX. (i.e.
fixer) alongside it, the third row down having the legend DRY. (i.e. dryer) alongside
it, the left-hand column having the legend TEMP. (i.e. temperature) above it, the
middle column having the legend pH above it and the right-hand column having the legend
FLOW above it. Thus, by pressing the key numbered 1, the value in degrees Centigrade
(°C) of the dryer temperature will be displayed (the LEDs 37 and 38 being energised
to indicate this); by pressing the key numbered 5, the value of the pH of the fixer
will be displayed (the LEDs 36 and 39 being energised to indicate this); by pressing
the key numbered 6, the value in millilitres (mL) of the flow of fixer will be displayed
(the LEDs 36 and 40 being energised to indicate this); by pressing the key numbered
7, the value in degrees Centigrade of the developer temperature will be displayed
(the LEDs 35 and 38 being energised to indicate this); by pressing the key numbered
8, the value of the pH of the developer will be displayed (the LEDs 35 and 39 being
energised to indicate this); and by pressing the key numbered 9, the value in millilitres
of the flow of developer, will be displayed (the LEDs 35 and 40 being energised to
indicate this).
[0015] For converting signals the stored in RAM 27 into corrected signals for display purposes,
there is provided on the main circuit board 3 a 256 bit non-volatile electrically
erasable programmable read-only memory 43 which stores appropriate calibration factors
and is connected with circuitry 22 via a four line bus 44. Finally, connected to an
output of the parallel input/output circuitry 22 of the main circuit board 3 there
is also provided a sounder 45 for producing an audible sound as will be described
below.
[0016] In typical X-ray film processing equipment, the developer and fixer baths operate
at about 32°C, and the dryers operate at about 55°C. Typically, the converter 19 spans
a 25°C range around these values with a resolution of 0.1°C, the display resolution
being in 0.1°C increments.
[0017] Typically, the pH probes 7 and 8 would cover a range from 0 to 14 in value, the developer
having a pH of about 10.5 and the fixer a pH of about 5.5. If the converter 19 has
a span of 2 to 13 this would give a resolution of 0.05 pH. Display resolution could
be typically in 0.1pH increments.
[0018] Typically, the display resolution for flow could be in 1 mL increments.
[0019] Eachs of the temperature sensors 9, 10 and 11 produces an output proportional to
absolute temperature and the output at room temperature needs to be offset to cover
the required range. In addition, the pH probes 7 and 8 need an offset to enable their
bipolar outputs to be measured by the unipolar converter 19. This offset voltage is
1/2 full scale of the converter 19 to give an equal range about the normal operating
point. Any errors in this voltage are corrected by the calibration routine which will
be described below.
[0020] Readings from the probes 7 and 8 and sensors 9, 10, 11, 12 and 13 are taken continuously,
and an average calculated for each of the temperature and pH channels. For the flow
sensors, the start and stop of flow is determined, and the volume for each film processes
is calculated.
[0021] Pressing the appropriate key on keypad 42 displays the value of the relevant parameter.
Five seconds after the key is released, the circuitry of the display board 31 returns
to a standby mode where only the centre segment of the middle display 33 is energised,
unless another valid key is pressed in which case the value of the new parameter is
displayed.
[0022] Pressing a valid temperature or pH key causes a short sound from sounder 45 and the
measured value is displayed for 5 seconds. Holding the key pressed gives a continuous
display.
[0023] Pressing a flow key causes a short sound from the sounder 45, and the display shows
0. Feeding in a film operates the replenishment pumps, and the display counts up the
volume of liquid passed. After the pumps stop, the display remains for 20 seconds.
If another film is inserted during this time, the display continues counting, enabling
the average volume per film to be determined.
[0024] Pressing an invalid key, for example key 2 (DRY. pH) results in a long sound from
sounder 45 and no display.
[0025] To ensure accuracy without analogue adjustments, a calibration routine may be used
whereby each of probes 7 and 8 and sensors 9, 10, 11, 12 and 13 is subjected to a
known condition, and the measured value entered into the device, calibration factors
for correction of future signals being stored in the non-volatile memory 43.
[0026] To ensure measurement accuracy at the normal operating levels without electrical
adjustments, calibration is performed by software via the keypad 42, and to prevent
tampering with the calibration factors, a three digit security code is used.
[0027] As with any calibration method, an independent reference is required for the parameter
being measured. This would normally be a thermometer for temperature, a pH meter or
buffer solution for the pH probes and a measuring cylinder or similar for flow. The
reference accuracy should better than the accuracy required from the hand-held device.
Before calibration, the processing equipment should be allowed to stabilise for 30
minutes after reaching normal operating conditions.
[0028] To calibrate for developer temperature, a reference thermometer is immersed in the
developer bath and the key marked CAL. and then key 7 (DEV.TEMP.) pressed. A particular
value will be displayed and if this is not correct, the correct value is entered (e.g.
32.3) via the keypad 42. The entered value then flashes on the display board 31. CAL.
is pressed and then the security code (e.g. 123) is entered via the keypad 42. After
a short delay, the device reverts to the standby mode, and a new DEV.TEMP. reading
should now agree with the reference.
[0029] At any stage, the calibration is aborted if the correct key is not pressed within
a certain time. Entering an incorrect security code results in "Err" being displayed
via displays 32, 33 and 34, and calibration is aborted.
[0030] To calibrate for dryer temperature, the procedure is the same as for developer temperature,
except that as the average of two sensors is used for the display, each can be individually
calibrated. Key 1 (DRY. TEMP.) is used to select the front dryer sensor for calibration,
and key 2 for the rear sensor. As the dryer temperature accuracy is not critical,
a single reference probe is normally adequate, and is used for both front and rear
sensor calibration.
[0031] To calibrate for pH, calibration of both developer and fixer pH is performed in a
similar fashion to the temperature calibrations, although the reference method used
requires some differences in procedure. Only a single calibration point is used, there
being no necessity to use the usual pH 7 point. The simplest method is to have an
independent pH meter and probe, and use this to measure the pH values of the bath
solutions. However, the probe must be capable of operating in a solution contaminated
with silver. An alternative method is to use buffer solutions with a value near to
the normal developer and fixer values. To do this, the probes must be removed from
the baths, rinsed in distilled water, and immersed in the buffer solution. The buffer
solution must be in electrical contact with the processing equipment, else the pH
values may be significantly incorrect. The simplest way to achieve this is to connect
a wire to the metalwork of the equipment, with the other end dipping in the buffer
solution. Note that the buffer solution should be at approximately the same temperature
as the bath solutions. Whichever method is used to obtain the reference value, the
calibration method proceeds as before.
[0032] To calibrate for flow, the replenishment pipes of the processing equipment should
be positioned to discharge into a suitable measuring cylinder. CAL. is pressed and
then a flow key. The displays 32, 33 and 34 read 0. The processing equipment's pumps
are activated by inserting a film. Several films should be used to pump a reasonable
volume (say 250 mL) into a measuring cylinder. The device will count up the total
volume passed. The volume in the cylinder should be accurately noted, and this value
keyed into the device as previously.
[0033] During the calibration procedure, unless otherwise stated, the device reverts to
the standby mode if no key is pressed for 60 seconds, and any calibration changes
are ignored.
1. A device for use in monitoring parameters during the processing of a film, comprising:-
a) means for receiving input signals dependent on the values of the said parameters
from sensing means which are responsive to the parameters;
b) means for processing the said signals;
c) display means coupled with the said processing means; and
d) selection means coupled with the said processing means for enabling the values
of the said parameters to be displayed selectively by the display means.
2. A device according to Claim 1, wherein the said receiving means is adapted for
receiving first such signals as analogue signals and second such signals as digital
signals.
3. A device according to Claim 2, wherein the said processing means includes conversion
means for converting the said analogue signals to digital signals.
4. A device according to any preceding claim, wherein the said processing means includes
storage means for storing processed signals, the said selection means being adapted
for selecting stored signals and causing them to be supplied to the said display means
for selectively displaying the values of the said parameters.
5. A device according to any preceding claim, wherein the said processing means includes
means for storing calibration values for calibrating processed signals.
6. A device according to any preceding claim, wherein the said selection means comprises
a manually operable keypad.
7. A device according to any preceding claim, wherein the said processing means includes
a central processing unit and memory means with a stored program for use in controlling
operation of the processing means.
8. A device according to any preceding claim which is a hand-held device including
the said receiving means, processing means, display means and selection means.
9. A device according to any preceding claim, wherein the said receiving means is
coupled with interface means having inputs for connection with respective ones of
a plurality of such sensing means an being adapated for supplying signals from the
sensing means to the receiving means.
10. A device according to any preceding claim, adapted so that the said parameters
comprise at least: the pH of a liquid used in the processing of a film; a temperature
occurring in the processing of a film; and a volume of liquid flow during the processing
of a film.