Electronic Replenishment Apparatus For Photographic Processor

Abstract

Apparatus is disclosed for processing film in which replenisher, developer and fixer solutions are supplied on demand, based on empirically determined requirements. The continuously moving fixed photographic film is light monitored to provide a plurality of modulated signals which are a function of the degree of transparency presented by the moving photographic film. The modulated signals are then fed to an integrator to provide integrated output signals which are a function of the average of the modulated signals and time. The integrated signals are then compared in a comparator, and a comparator output signal is provided when the integrated signals equal or exceed a fixed voltage level. The comparator output signals are then counted to provide a control output signal when a predetermined number of counts has been reached. In response to the control output signal, fresh developer and fixer solutions are then supplied to replenish the spent developer and fixer solutions.

Description

BACKGROUND OF THE INVENTION

This invention relates to an automatic electronic replenisher apparatus for an automatic photographic film processor. In modern day high speed film processing exposed film is fed through an automatic processor at a very rapid rate of speed, the film being fed into the processor at one end and retrieved at the other end, fully developed, fixed, washed, and dried. Because of the high speed, it is obvious that the photographic solutions are depleted at a fairly rapid rate, so that replenishment is in order.

In the past, replenishment has been primarily initiated by the machine operator, using such aids as test film strips and the like, but in the main, reliance was based on experience, together with knowledge of the work load for the day. This practice has been more or less successful, depending mostly upon the experience and attentiveness of the human operator.

SUMMARY OF THE INVENTION

The instant invention provides an accurate means for supplying developer and fixer solutions to an automatic film processor based on empirical demand, thereby eliminating reliance upon the vagaries of human nature. The continuously moving fixed photographic film is light monitored at a light collecting station to provide a plurality of modulated signals which are a function of the degree of transparency presented by the developed and fixed photographic images over an incremental area of the processed film. The modulated signals are then delivered to an integrator which provides integrated output signals which are a function of the average of the modulated signals and time. The succeeding integrated output signals are then applied to comparator means which provide a comparator output signal when the integrated output signals equal or exceed a fixed voltage level. The comparator output signals are counted by counting means which derive a control output signal when a predetermined number of counts has been reached, and in response to the control output signal, additional developer and fixer solutions are supplied to replenish the spent developer and fixer solutions.

Accordingly, it is an object of this invention to provide an electronic replenisher apparatus for an automatic film processor, for quickly and automatically supplying the correct amount of developer and fixer solutions required to keep the photographic solutions at all times at a high level of efficacy, based on timely and empirically determined demand.

The novel features which are believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing, showing an automatic film processor together with the addition of the electronic replenisher apparatus in accordance with the instant invention;

FIG. 2 is a schematic showing the light collecting station of the automatic electronic replenisher apparatus in accordance with the invention; and

FIG. 3 is an electrical schematic showing the electronic circuitry of the electronic replenishment apparatus in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The instant invention has particular utility in an automatic photographic film processor, in which the exposed photographic film is fed into a processor unit, where it is successively developed, fixed, washed, and dried. The overall environment in which the invention is intended to be utilized, may best be appreciated by reference to FIG. 1, which depicts such an automatic film processor, equipped with an automatic electronic replenisher control apparatus, utilizing the principles of the instant invention.

The processor, indicated generally at 10, is arranged so as to straddle a dark room wall panel 12, the side of the wall panel identified at 14 being a darkroom, and the side 16 being operated under normal lighting arrangements. The film loading station indicated generally at 18, is the only part that extends into the darkroom 14; the balance of the processor unit occupies a normal room-lighted area, since the remaining portion of the film processor 10 is enclosed within a light tight container indicated at 20. The entering film F is successively advanced by roller transport racks indicated generally at 22, through the developer tank 24, the fixer tank 26, and the wash tank 28.

The film F is prepared for drying by passing through a water subtractor indicated generally at 30, positioned at the entrance to the film drying section indicated generally at 32. The film dryer section 32 comprises a columnar arrangement, in which the film is transported by roller transports (unnumbered) toward the exit end. An air blower indicated at 34 forces thermostatically controlled, warm filtered air, through a plurality of tubes indicated at 36, to insure uniform drying.

Upon leaving the film dryer section 32, the film is monitored by the automatic electronic replenisher control apparatus in accordance with this invention. The dried film is first passed through a light collecting station indicated generally at 38. Here, the film is monitored by the light collecting system to determine the areas which have been photographically developed, to thus provide a measure of the work performed by the developer and fixer solutions. The light information gathered by the light collecting system is fed to electronic circuitry indicated generally at 40. In effect, the electronic circuitry 40 provides a signal when the developer and fixer solutions have performed a measured amount of chemical activity. The signal from the electronic circuitry 40 is then used to pulse a stepper motor 42, which is adapted to rotate or advance in discrete steps. When the stepper motor 42 has rotated through a predetermined total angular displacement, it actuates a microswitch indicated generally at 44; the microswitch 44, upon actuation, initiates timers 46 and 48, which functionally serve for the developer and the fixer solution, respectively. The timer 46 actuates a pump 50, which operates through a flow meter 52 to deliver fresh developer solution to the developer tank 24. Similarly, the timer 48 actuates a pump 54, which, through a flow meter 56, supplies replenishment solution for the fixer tank 26.

The light collecting station 38 is shown in greater detail in FIG. 2. It should be made clear at this point that the light collecting station need not be located at the exit of the film dryer section 32. It is within the scope of this invention to place the light collecting station or system 38 where the film exits from the wash tank 28. Once the film is fixed and no further change on the developed image can take place, it is perfectly feasible to arrange the light collecting system at any convenient location after the fixer tank.

The light collecting system 38 comprises s source of illumination which may be a light bulb 58. It is preferable to use a single source of illumination, so that as the source 58 ages and blackens, the film to be monitored will everywhere be affected in the same degree. If more than one source of illumination is used, there is created the problem of matching each light source.

The light from the source 58 is then variously modulated, depending upon the developed or undeveloped areas presented by the moving film F. The light here indicated only by a single principal ray 60, is reflected by a 45.degree. mirror 62 to a lens system, here indicated symbolically by the double convex lens at 64. The light from the optical system 64 is focused on a photovoltaic cell 66, which may be a selenium photocell. The light, unmodulated by any moving film, is also imaged onto another photovoltaic cell indicated at 68, the unmodulated light from the lamp 58 being brought to the vicinity of the photocell 68 by any convenient means such as a piece of Lucite 70, which may be conveniently bent to transport the light from the lamp 58 to the locus of the photocell 68. As may be seen from the drawing, the photovoltaic cells 66,68 are a part of the electronic circuitry 40.

While the cells 66, 68 are here illustrated as photovoltaic cells, it should be understood that any photoelectric transducers may be used. That is, the transducers may be photovoltaic or photoconductive.

The electronic circuitry 40 may be studied in greater detail by reference to FIG. 3. The photovoltaic cells 66,68 have their cathodes connected to the ends of the potentiometer 72, as shown, the variable tap 74 of which is connected to ground. The anodes of the photovoltaic cells 66,68 are connected respectively as inputs to a differential amplifier, indicated generally at 76. The differential amplifier 76 is an operational amplifier well known in the art. A variable resistor 78 is connected in the feedback path of the differential amplifier 76, from the output terminal to the anode of the photovoltaic cell 66. A monitoring voltmeter 80 is connected in the output of the differential amplifier 76 as indicated. The output of the differential amplifier 76 is connected by means of resistor 82 to the input of an operational amplifier arranged as an integrator and indicated at 84. Capacitor 86 is connected in the feedback path of the integrator 84.

The output of the integrator 84 is connected to one input of comparator 88 by means of input resistor 90. The comparator is a high gain differential input signal ended output amplifier. The other input to the comparator 88 is a reference voltage which is connected to the input by means of resistor 92. The comparator 88 also includes a feedback resistor 94. The comparator output is connected to a PNP transistor 96 by means of resistor 98, which is connected to the base thereof. A pair of serially connected diodes 100,102 are connected between the emitter of the transistor 96 and ground, the cathode of diode 102 being connected to ground and the anode of diode 100 being connected to the emitter of transistor 96. The emitter is also connected to a voltage source which may typically be 24 volts, by means of a resistor 104.

A relay is indicated generally at 106. The relay 106 is of the electromagnetic type having its coil connected serially with the collector of transistor 96, and in shunt with diode 108, observing the polarity as shown; the relay 106 also includes contact pairs 110,112 and 114,116. The contact arms of the relay 106 are normally closed with contacts 112 and 116 as shown in FIG. 3. Further, it should be noted at this point, that the contact pairs 110,112 are arranged in shunt with the capacitor 86, the purpose for which will presently be made clear.

The contact pair 114,116 is in the energizing circuit of the stepper motor 42, as shown. The stepper motor 42 is of a type well-known in the art; it consists of a permanent magnet rotor and an electromagnetic stator. The rotor shaft rotates in discrete steps of angular displacement in response to energy supplied to its coils 118,120 by means of a source such as a battery 122.

The microswitch 44 has a movable element 124 connected to a source of potential +24 volts through a resistor 126. The movable element 124 is connected to a capacitor 128 and resistor 126 as shown. The movable element 124 is also arranged to be displaceable between contacts 130,132. The latter contact 132 enables microswitch 44 to be connected to the coil of relay indicated generally at 134, the other side of the relay coil being connected to ground. The relay 134 includes contact pairs 136,138 and 140,142. The contact arms of relay 134 are normally closed to contacts 138 and 142. As will be seen, the contact pairs 136,138 are associated with the timer 48, pump 54, and flow meter 56, while the contact pairs 140,142 are operatively associated with timer 46, pump 50, and flow meter 52.

OPERATION OF THE DEVICE

Before using the processor, it is first necessary to calibrate the device properly. This is done by closing switch S (FIG. 3) and passing through the light collecting station 38 a strip of film of either perfectly clear film, or film of selected minimum density. The tap 74 of the potentiometer 72 is then adjusted so as to provide a zero reading or a minimum voltage reading on the voltmeter 80. Next, a strip of film of either selected maximum density or completely black (100 percent developed) film is passed through the light collecting station, and the gain of the amplifier 76 is adjusted by means of variable resistor 78 to provide maximum voltage on the voltmeter 80. The purpose of this adjustment is to provide a substantially linear output between 0 and 100 percent development or between D.sub.min and D.sub.max of the photographic film. The replenishment apparatus is then linearly calibrated, and the voltmeter is then disconnected by means of switch S.

In normal operation as the film is passed through the light collecting station, the photovoltaic cells 66,68 will develop the highest voltage under clear film or no film conditions. This is the standard provided by the photovoltaic cell 68. The photovoltaic cell 66 then monitors the photographically fixed film, and the resulting modulated light it receives is a function of the varied transparency presented by the fixed film, thereby developing a variable signal voltage.

The output of the differential amplifier 76 is:

e.sub.o = K (e.sub.2 - e.sub.1)

where

e.sub.o = the output of the differential amplifier;

K = the gain of the amplifier 76 as determined by the adjustment of the resistor 78;

e.sub.1 = the standard voltage developed by the photovoltaic cell 68; and

e.sub.2 = the voltage developed by the photovoltaic cell 66.

The output e.sub.o of the differential amplifier 76 is applied to the integrator 84, and as a result, a charge is built up on the capacitor 86.

Under one typical set of operating conditions, the voltage reference V.sub.ref of the comparator 88 is set at very nearly -4 volts. In the "off" condition, the output of the comparator 88 was then approximately +3.2 volts with respect to ground, thus placing the base of the transistor at +3.2 volts with respect to ground. As the result of the conduction of the +24 volt supply through the resistor 104 and through the serially connected diodes 100,102, the emitter is clamped at about +1 volt above ground. This is the "off" condition of the apparatus. Since the emitter is at +1 volt with respect to ground, therefore, the emitter-base junction of transistor 96 is biased to cut off. As the monitored film is passing through the light collecting station 38, charge continues to build up on the capacitor 86. When the input from the integrator 84 to the comparator 88 equals or exceeds -4 volts, the comparator develops an output, the comparator 88 output potential dropping then to approximately -0.5 volts with respect to ground. Since the emitter-base junction is now forward biased, the transistor 96 conducts, driving the base to +0.7 volts or very nearly +1 volt with respect to ground. The result of the conduction of the transistor 96 causes collector current to flow through the coil of relay 106 and the relay 106 is momentarily energized, closing the contact arms to the contacts 100,114 respectively.

The stepper motor 42 could be operated by a flip-flop circuit, but it here is arranged with constant current to one winding 118, with pulses supplied to the other winding 120 when the relay 106 is energized. It will be noted that the closing of the contact arm to contact 114 energized the coil 120 of the stepper motor 42, causing the motor 42 to rotate one step, which may be in the order of 15.degree. of angular displacement. The closing of the relay contact arm to contact 110 effectively shorts out the capacitor 86. The diode 108 helps to maintain the current through the coil of relay 106.

The discharging of the capacitor 86 effectively returns the circuit to the status quo, and the transistor 96 again becomes cut off, the contact arms of relay 106 returning to their normal position, engaging contacts 112,116. The process is repetitive and cumulative as the film continuously passes through the light collecting station 38. The charge on capacitor 86 builds up either at a slower or a faster rate, depending upon the condition of the film being instantly monitored, resulting in the transistor 96 successively conducting earlier or later, as the case may be to actuate the relay 106. Each actuation of the relay 106 causes the stepper motor 42 to be indexed one angular displacement, or one step. The shaft of the stepper motor 42 contains a cam wheel which is so positioned that after the motor shaft has rotated a predetermined total angular displacement, a slot in the cam wheel actuates the movable element 124 of the microswitch 44.

Considering the microswitch 44 for a moment, it will be noted that the capacitor 128 is charged through the resistor 126 by reason of the connection to the +24 voltage source. When the slot of the cam wheel of the stepper motor 42 reaches the movable element of the microswitch 44, it is displaced, making contact with post 132, and the charged capacitor 128 now discharges itself through the coil of the relay 134. The rapid discharge of the capacitor 128 through the coil of the relay 134 causes the relay contact arms to close with contacts 136,140, respectively. This causes the timers 46,48 to be energized, the timer 46 being for the developer solution and the timer 48 being for the fixer solution. The timers 46,48 are standard timers of a type well known in the art, and they may be set from 1 second to 60 seconds or more. Each timer actuates its respective pump for the desired time interval. The flow meters 52,56 have been set so as to deliver a predetermined number of milliliters per minute, so that the pumps then force the developer solution and fixer solution, respectively from sources (not shown) to the respective tanks 24 and 26, in the correct volumetric amount to provide replenishment solutions based on empirically determined demands.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention, as described hereinabove and as defined in the appended claims.

Claims

I claim:

1. Replenishment apparatus for a photographic film processor comprising:

a. transducer means responsive to light modulated by the continuously moving photographically fixed film to provide a plurality of modulated signals which are a function of the instantaneous degree of transparency presented by the fixed photographic film, respectively;

b. integrator means comprising an operational amplifier having capacitive means in its feedback path for integrating the plurality of modulated signals to provide integrated output signals which are a function of the average of the plurality of modulated signals and time, respectively;

c. comparing means for comparing the integrated output signals and for providing a comparator output signal when said integrated output signals equal or exceed a fixed potential level;

d. a motor having cam means on its shaft located a finite angular displacement from a start position, said motor upon energization being adapted for rotation in incremental steps;

e. a first electromagnetic relay having a first coil, and first and second contact pairs, said first pair of contacts being arranged to energize said motor upon closure; said second pair of contacts being arranged to discharge said capacitive means upon closure;

f. a transistor having said first coil connected serially with one of its electrodes, said transistor being arranged to be conductive upon the receipt of one of the comparator output signals to energize said first coil, thus causing said first and second contact pairs to close;

g. a second electromagnetic relay having a second coil and third and fourth contact pairs;

h. first flow control means operatively connected with said third contact pair to control the flow of fresh developer solution;

i. second flow control means operatively connected with said fourth contact pair to control the flow of fresh fixer solution; and

j. switching means positioned in operative relation with said cam means, having open and closed positions, and in the closed position being arranged to energize said second coil of said second electromagnetic relay, whereby when said cam means has rotated through a predetermined angular displacement, said cam means forces said switching means into closed position, energizing the second electromagnetic relay to actuate said third and fourth contact pairs, the first and second flow control means then supplying fresh developer and fixer solutions to the processor to replenish the partially spent developer and fixer solutions.

2. Apparatus for processing extended lengths of a radiation sensitive medium, said apparatus comprising:

a. source means disposed to direct radiation through the length of the radiation sensitive medium as the length of the radiation sensitive medium is removed with respect to said source means;

b. first and second radiation sensitive devices, said first radiation sensitive device being disposed to receive the modulated radiation derived from the length of the radiation sensitive medium to provide a first signal indicative thereof, said second radiation sensitive medium means being disposed to receive unmodulated radiation from said source means to provide a second signal indicative thereof;

c. differential means responsive to the first and second signals to provide a third signal indicative of the difference between the first and second signals;

d. integrator means for integrating the third signal to provide a fourth signal indicative thereof;

e. comparing means for comparing the fourth signal with a predetermined value and for providing a fifth signal when the fourth signal exceeds the predetermined value;

f. counting means for counting the number of received fourth signals to provide a fifth signal when a predetermined number of fourth signals have been received; and

g. means for applying a processing agent in response to the fifth signal.

3. Apparatus as claimed in claim 2 comprising:

a selectively variable impedance element having first and second terminal ends;

said first and second radiation sensitive devices each comprising first and second terminals, said first terminals of said first and second radiation sensitive devices being connected respectively to said first and second terminal ends of said variable impedance element, the impedance presented by said variable impedance element determining the sensitivity of said first and second radiation sensitive device, said second terminals each being connected to said differential means; and said differential means comprising an operational amplifier having an input terminal and an output terminal, a second variable impedance element disposed between said input terminal and said output terminal, the impedance presented by said second variable impedance element determining the maximum radiation sensitivity of said apparatus.