US3442589A - Sensitized paper development device - Google Patents

Description

Sheet of '4.

May 6, 1969 TOSHIO ISHIKAWA E A SENSITIZED PAPER DEVELOPMENT DEVICE Filed May 16, 196'? Fig a m b. UV. c w m m 6 d V d m M .w 6 m C m. I 3 0 D 2 I .m d V m m g C 9 b .l m F C n F b b O 0 ll EEEwQEE. Al D C BA I? 220595 62m Development velocity y 5, 1969 TOSHIO ISHIKAWA ET AL 3,442,589 Y SENSITIZ ED PAPER DEVELOPMENT DEVICE Filed May 16, 1967 Sheet 2 of 4 Fig4 Temperature -Developmem velocity Fig 5 6, 1969 TOSHIO lsHlKAwA ET AL- 3,442,589

SENSI'IIZED PAPER DEVELOPMENT DEVICE Filed May 16, 1967 sheet 3 of 4 i 3T- I i FIG.6

I; 26 23 Q] 37i i Exposed Q- Sens/rive Paper Original POP! Sens/live Paper M y 6, 1969 TOSHIO ISHIKAWA ET AL 3,442,589

SENSITIZED PAPER DEVELOPMENT DEVICE Filed May 16, 1967 Sheet 4 of 4 F IG. 9

475 K 465 W 455 A ,4 J M United States Patent U.S. Cl. 355-'106 5 Claims ABSTRACT OF THE DISCLOSURE An apparatus for heat development of positive sensitized paper which exposes sensitized paper first to a light source and then to a heat source. An electric curcuit in the device simultaneously controls both the velocity of the paper moving past both sources and the developing temperature.

Related applications This application is a continuation-in-part of application Ser. No. 399,784, filed Sept. 28, 1964.

Background The invention relates to copiers, and more specifically, to light exposure and heat developer copiers having velocity and temperature control circuitry.

temperature by compensating for any temperature changes due to heat absorbed by the sensitized paper during development. The velocity of the paper moving past the heat source is usually controlled by a motor driving a belt which carries the paper around the heating source. Both the temperature and the development velocity must be considered so that the heat quantity necessary for sensitized paper is radiated uniformly over the 7 paper surface.

Since it is generally desirable that he quantity of heat generated orithe paper surface be approximately constant during development the ratio of the development temperature and the paper velocity past the heat source, should also be approximately constant. If the operating temperature is changed to a higher level the velocity should be increased correspondingly, or if the temperature is lowered the velocity should be lowered.

In addition to maintaining an optimum relation between the temperature and the velocity of paper movement in the development stage, it is desirable in positive printing machines to synchronize the velocity of the sheet of paper moving through the light exposure stage with that of the developing stage. When synchronization between the stages is not maintained, a portion of the paper inserted in both of the stages becomes either stretched or damaged; when the development stage velocity exceeds the light exposure stage or when the developing velocity falls below that of the light exposure stage, a back up of light sensitized paper occurs causing stagnation of the paper prior to the development stage. Finally, it is necessary to provide some flexibility in temperature range set- 3,442,589 Patented May 6, 1969 tings of the developer in order satisfactorily to develop prints from different shades of original paper.

In the past positive printing developers have not been entirely satisfactory in maintaining optimum heating characteristics when ether the velocity ofthe sheet or the developer temperature was changed to any degree-These devices also have failed to synchronize the paper sheet transportation rate through both the light exposure and heat developing stages and have experienced difiiculties in compensating for heat losses in the development stage due to the removal of heat by the sensitized paper.

It is an object therefore to overcome the foregoing limitations and difiiculties by providing anovel copier apparatus.

' Summary A novel copier for positive print developing is obtained by the provision of a novel developer temperature and sheet velocity control circuit in combination with a light exposure device and a heat developer device. With the copier of this invention, it is possible to adjust development velocity to varying temperature ranges in accordance with the shade of color of the original paper while the exposure velocity is maintained constantly synchronized with the developing velocity. Heat development efiiciency is maximized with an automatic adjusting control circuit which varies both the heat source temperature and the sheet velocity simultaneously, thus providing a continuous temperature velocity relationship.

Brief description of the drawings FIGS. 1-4 are graphs showing relationships between the temperature and velocity of development;

FIG. 5 is a circuit diagram illustrating a control circuit of the invention;

FIG. 6 illustartes light exposure and heat developing stages of a copier in accordance with the invention;

. FIG. 8.

Description 0f the preferred embodiments Referring now to the drawings, the graphs of FIGS. 1-4 shows the manner in which the temperature and the developing velocity may be related. Normally when the velocity of movement of the developing portion of a copier becomes higher, .the temperature should be higher and as it becomes lower the temperature should be lower. Sensitized paper becomes scorched below a, and the development is incomplete above a. Each corresponding velocity may have some tolerance, such as M, b-b, etc. in FIG. 1, and may overlap to a certain degree as temperature is increased A, B, C, D. If, as in FIG. 2, satisfactory developing velocities do not overlap with increases in temperature, a gap n-m in the developing section could result if optimum operating out by two stopping rollers 18 and 19. Both the original paper and light sensitized paper are combined together and inserted in the direction of the arrow between the belt; which is-revolved by driving -roller'12 and-the periphery of cylinder 20.

The developing stage 26 has a heating roller 31 which rotates around a heating source 30. The heating source may be, for example, a heating wire such as a Nichrome wire, or an infrared ray lamp. A belt 36 is wound around rollers 32, 33, 34 and 35 for carrying light-sensitized paper aroundthe heating roller. A heat insulatingmaterial 37 covers the rollers 32-35 and belt and shields the heating roller 31. When light-sensitized paper, which has been exposed in the light exposure stage, is inserted between the heating roller 31and the belt 36, it is developed while the paper is revolved around the periphery of roller 31. Thelight exposure and-developing stages are shown being driven byythe same chain or belt linkage 22 from a gear 23 which may be-connected to the drive shaft of t a motor- 9 (FIG. The rotation of the linkage 22 rotates both. gear 25 on the developing section and gear 24 in the exposure section.

As-well known in the art, the. phase relation between the input and'output voltages. of an AC bridge is reversed as one or more branch impedances of the bridge are varied from one side-of the 'balance point of the bridge to the opposite side thereof. Accordingly, it is possible to form an AC bridge circuit consisting of an arm including a thermistor located at a desired temperature measuring point and the remaining three arms each including a resistor, so that for a given constant input voltage to the AC bridge, the polarity of the phase angle of the output voltage therefrom can be changed depending on whether the temperature of the thermistor is in excess of or is less than a certain preselected value, which value is determined as a function of the temperatureresistance characteristics of the thermistor and resistance values of resistors of the three arms of the bridge. With the provisions of a phase discriminator circuit to check the polarity of the phase angle of the output voltage from the bridge and an electric heater connected to the phase discriminator circuit, then it is possible to switch on and switch off the heater in response to each change-over of the polarity of the phase angle of the output voltage of the bridge and hence in response to the temperature variation of the thermistor passing a certain preselected value determined by the design of the bridge.

In FIG. 5, the circuit includes a thermistor 1 in a bridge leg, resistance leg 2 having a plurality of temperature setting contacts F, G, H being separately switched into a bridge circuit 3 that is connected to AC amplifiers 4 and S which are in turn connected to a phase discriminator 6 that controls operation of a relay a power transformer 11 is the power source for the circuit and 'the temperature setting contacts F, G, H are interconnected with speed control means 7 and 8 for the motor 9.

In the particular embodiment of the AC bridge shown in FIG. 5, one arm consists of the thermistor 1 located at a desired temperature measuring point and another arm is adapted to be selectively connected to one of the resistors in resistance leg 2 for facilitating the temperature setting, while the remaining two arms consist of resistors R and R of identical resistance values connected by a variable resistance R for adjustment. The AC amplifiers 4, S consist of PNP type transistors 4T and ST, respectively, and the phase discriminator circuit 6 is also made of a PNP type transistor 6T. The coil L1 of relay 10 is connected to the transistor of the phase discriminator circuit 6 as a collector load thereof, so that the relay 10 is energized when the transistor is conductive, and the relay contact is closed. The relay contact is kept open as long as the transistor of the discriminator circuit 6 is nonconductive.

The power source transformer 11 is provided to apply a half-way rectified voltage across the collector and the emitter of the transistor 6T through suitable diodes. As far as direct voltage is concerned, the emitter and the base of the transistor'of the circuit 6 are at the same poential.

A collectorcur-rent flows through-the relay 10 if the emitter is made positive with respect to the base of the transistor 6T during the period when the emitter is kept positive with respect to the collector, namely, during the positive half cycle of the power source voltage. If an AC voltage applied acrossbthe emitter and the base of the transistor 6T' in the aforesaid phase relation with the power source voltage, then the collector current flows during each positive half cycle of the power source voltage. On the other hand, if the AC voltage across the emit.- ter and the base of the transistor 6T is so phased as to keep the emitter negative with respect to the base during the positive half cycle of the power source voltage, then the transistor is'kept nonconductive and'the'relay 10 is not actuated. v

In FIG. 5, the temperature and velocity control circuit is used to continuously control sheet velocity and heat developer temperature in a copier such as that illustrated in FIG. 6. A predetermined temperature setting is first made at resistor 2 with one or more contacts F, G, H beingswitched into the bridge circuit. 'At the same time, the variable speed control transformer 8 has appropriatetaps f, g, h, etc. connected to a full wave rectifier comprising diodes D D D and D Under optimum developing conditions bridge 3, comprising resistors R R R thermistor 1 and variable selection resistors 2, is balanced. 'Ihermistor 1 is located in the vicinity of the heat-development roller and detects any changes in temperature. If the bridge becomes unbalanced, a signal is'pickedup at variable resistor R and is transmitted through capacitor C to the amplifier 4. The signal passing through capacitor C goes through a voltage divider and resistor R connected to the base of transistor 4T. The voltage dividing circuit consisting of and RC network R C and a resistor R is connected between capacitor C and resistor R The amplifier transistor 4T has a resistor R and capacitor C connected in parallel between the emitter and junction A of the bridge network. The amplifier transistor 4T has a DC current path through resistor R resistor R and diode D to winding L of transformer 11.

, An AC path exists through capacitor C voltage divider network comprising resistors R R and resistor R to the base of transistor ST. A current limiting diode D is connected between the base and emitter electrodes of transistor 5T. An output signal from the collector of transistor ST is coupled through RC network C and R to the base of relay transistor 6T. When transistor 61 has a collector output signal through inductor L and capacitor C relay 10 is actuated in order to control the amount of heating current to be applied to the heating source.

The output circuit of transistor 6T is completed through diode D and winding L A capacitor C is connected in a conductor extending from a junction 38 between the bridge legs 1 and 2 and a junction between resistors R and R Winding L is connected between two junctions of the bridge circuit and the primary winding L, of transformer 11 is connected to a suitable power source.

The transformer 8 includes a primary winding L connected to a suitable power source and a secondary winding L providing variable speed control to motor 9 through the full wave rectifier consisting of diodesD D D and D A motor coil L provides feedback signals through a full wave rectifier consisting of diodes D D D and D for a DC control signal through winding L to insure synchronization of motor 9 at the desired speed. The three transformer taps f, g and h are separately switched to a junction 39 which is connected to the junction between diodes D and D If it is assumed in FIG. 5 that the two secondary windings L and L of the power source transformer 11' are so connected that corresponding ends are simultaneously made positive with respect to the opposite ends thereof, and if it is further assumed that the variableresistor R for adjustment isset at the center point thereof and the resistance of the thermistor 1 is higher than the particular resistance 2 selected at the particular moment,

which means that the temperature of the thermistor lo cated at the desired measuring point is lower than a preselected temperature setting made on the resistor 2, then the output voltage from the bridge 3 is applied to the transistor 4T across the emitter and the base thereof in such polarity that the emitter is kept positive with respect to the base during the positive half cycle of the power source voltage applied to the transistor 6T, namely, that half cycle when the emitter of the transistor 6T is kept positive with respect to the collector of the same. Since the power source voltage to the amplifier circuits 4 and 5 is half-wave rectified by diodes and then applied thereto through filter circuits consisting of resistors and capacitors, the transistors 4T and ST of the amplifier circuits are made conductive under such conditions throughout each cycle. Thus, the output voltage from the bridge circuit 3, which is applied to the amplifier circuit 4, is amplified by the AC amplifier circuits 4 and 5, and then applied to the phase discriminator circuit 6. Due to the fact that the output and input voltages are in phase in the case of a two-stage AC amplifier of resistor-capacitor coupling type as shown in FIG. 5, the output voltage of the bridge circuit 3 is amplified and applied to the transistor 6T across the emitter and base thereof after being amplified without any phase-shifting. Thus, as described above, in the transistor 6T, the emitter is'made positive with respect to the collector in synchronism with the AC voltage making the emitter positive with respect to the base. Thereby, the transistor 6T is made conductive to actuate the relay 10 and the relay contact is closed. Upon closure of the relay contact, an electric heater in the developing portion is energized or switched on to heat up the developing portion.

As the temperature of the developing portion is raised by such heating, the temperature of the thermistor 1 located in a suitable measuring area of the developing portion 26 is also increased, and accordingly, the resistance of the thermistor becomes lower. When the resistance of the thermistor is lowered to the same value as that of the resistor 2 preselected for temperature setting, the bridge circuit 3 is balanced, and the output voltage from the bridge becomes zero. Thus, no voltage is applied to the transistor 4T as an input voltage thereto, and the transistor 6T becomes nonconductive to deenergize the relay 10. Consequently, the contact of the relay 10 is opened and the electric heater is switched off.

If there is a considerable time delay between the heating effect of the electric heater and the temperature of the thermistor 1 in the developing portion to cause temperature rise even after switching off the heater, the resistance of the thermistor is excessively lowered beyond the value for proper balance of the bridge circuit 3 to again unbalance the bridge. However, the output voltage from the bridge circuit 3 under these conditions is produced in exactly opposite phase relation to the power source voltage applied to the transistor 6T; namely, when the collector of the transistor 6T is made positive with respect to the emitter by the power source voltage from the bridge circuit 3. Thus, the transistor 6T is kept nonconductive.

With the electric heater switched off, the temperature of the developing portion 26 is gradually reduced to increase the resistance of the thermistor 1, and when the resistance value of the thermistor is increased in excess of the aforesaid preselected resistor for setting, then the balance of the bridge circuit is again broken in the same manner as described above. Thus, the transistor 6T of the discriminator circuit 6 is made conductive to energize the electric heater.

As a result of it, when the temperature of the thermistor is low and the resistance thereof is larger than that of a resistor 2 preselected for temperature setting, the heater is switched on. On the other hand, when the temperature of the thermistor is high and the resistance thereof is smaller than that of the resistor for temperature setting, the heater is switched off. By providing a plurality of different resistors having suitable resistance values for temperature settings, the temperature setting can be changed by selectively connecting one of such resistors to the bridge circuit 3. By the operation of the variable resistor R for adjustment, the temperature setting can be made with fine adjustment.

Two embodiments which may be used to interconnect the temperature control circuit with the motor speed control are shown in FIGS. 7 and 8. In FIG. 7 changeover contact members 41 and 42 are spacedly mounted on a spindle 44 attached to a dial 43. The switching members 41 and 42 always make contact with junctions 38 and 39, respectively, but are switchable between contacts F, G, H, and f, g, h, respectively, so that any change in temperature setting makes a corresponding velocity change and vice versa.

With the dial 43 positioned as illustrated in FIG. 7, the secondary tap g of the transformer 8 is connected to the rectifier bridge through the rotary member 41, and a direct voltage from the rectifier bridge is applied to the armature of the DC motor 9. The other rotary member 42 connects a temperature setting resistor G to the bridge circuit 3. Thus, the revolving speed of the motor 9 is determined by the voltage appearing on the secondary tap g of the transformer 8 thus selected, and the temperature of the developing portion is regulated by the temperature setting resistor 26 thus connected to the bridge 3.

When the dial 43 is rotated in a counterclockwise direction from the position of FIG. 7, the revolving speed of the DC motor 9 is determined by a secondary tap h of the transformers 8, while the temperature of the developing portion is regulated by the temperature setting resistor 2H. Conversely, if the dial 43 is rotated in a clockwise direction from the position of FIG. 7, the revolving speed of the motor 9 is determined by the secondary tap f of the transformer 8, while the temperature of the developing portion is regulated by the temperature setting resistor 2F.

FIG. 8 shows another example of setting device of the revolving speed and developing speed by means of microswitches and a variable single winding transformer, in which three earns 45, 46 and 47 are secured to the dial shaft 44 so as to cooperate with microswitches 455, 465 and 475, respectively. Also secured to the dial shaft is a rotary contact arm 42 of the variable single winding transformer 2VR. With the setting dial positioned as shown in FIG. 8, only the microswitch 475 is actuated. As the setting dial 43 is rotated in a counterclockwise direction, the microswitches 465 and 475 are actuated successively, and finally all the microswitches 455, 465 and 475 are actuated simultaneously. If the setting dial 43 is turned to the extreme end of the clockwise direction, all the microswitches 455, 465 and 475 are switched off simultaneously. The rotation of the contact arm 42 of the variable single winding transformer 2VR is so arranged that it is not possible to transfer from the condition of simultaneous actuation of the microswitches to the condition of the simultaneous switching-off of all microswitches and vice versa.

FIG. 9 illustrates four temperature range adjustments by means of four resistors K, L, M and N and with corresponding changes in development velocity. The temperature setting resistors to be connected to the bridge circuit 3 under each operative condition of the microswitches are shown in the following table.

TABLE Conditions Microswitch No. I

In the particular example shown-in FIG. 8, the combination of the cams and the microswitches can take only four positions designated by conditions I to IV in the table, and the microswitches are always in one of the four conditions selected by suitable combinations of the cams 45, 46 and 47. Thus, the revolving speed is regulated by the rotation of the contact arm of the variable single winding transformer ZVR, and at the same time the temperature setting of the developing portion can be switched over in a very reliable manner.

What is claimed is:

1 1. In apparatus for heat development of positive sensitized sheets, the combination comprising, an exposure device having a light source and first means for moving an original copy and a sensitized sheet conjointly past said light source to expose said sensitized sheet; a heat development device. having a heat source and second means for moving the exposed sensitized sheet past said heat source to develop said sheet; switch means selectively operable to connect said heat source to a source of potential; a thermistor operatively associated with said heat development device and subjected to the temperature therein; an electric control circuit including an A.C. bridge, amplifier means connected to the output of said bridge and a phase discriminator connected to the output of said amplifier means, said thermistor being connected in an arm of said bridge; means applying a first A.C. potential to the input of said bridge and a second A.C. potential to said phase discriminator, said first and second A.C. potential being in phase coincidence; the amplified output potential of said A.C. bridge constituting a third A.C. potential which is applied to said phase discriminator; said switch means being connected to said phase discriminator and closed thereby when said second and third A.C. potentials are in substantial phase coincidence; the phase of said third A.C. potential, relative to that of said first and second A.C. potentials, being dependent on the resistance value of said thermistor; said third A.C. potential being substantially in phase with said second A.C. potential when the resistance of said thermistor is above a selected value, and being in phase opposition with said second A.C. potential when the resistance of said thermistor is below said selected value.

2. In apparatus for heat development of positive sensitized sheets, the combination claimed in claim 1, including an adjustable resistance in said bridge for setting said selected value; the output of said bridge being zero when the resistance of said thermistor is at said selected value.

3. In apparatus for heat development of positive sensitized sheets, the combination claimed in claim 1, in which said amplifier means comprises an RC coupled two-stage amplifier.

4. In apparatus for heat development of positive sensitized sheets, the combination claimed in claim 3, in which the stages of said amplifiers comprise transistors having said second A.C. potential applied to their outputs; said phase discriminator comprising a transistor having said second A.C. potential applied to its collectoremitter circuit; said switch means comprising a switch operating coil in the collector circuit of the transistor of said phase discriminator; the output of said bridge being applied to the input of the transistor of the first stage of said amplifier.

5. In. apparatus for heat development of positive sensitized sheets, the combination claimed in claim 1, including plural resistors of respective different resistance values included in an arm of said bridge and each having one terminal commonly connected to one input terminal of said bridge; first selector switch means selectively operable to connect the other terminal of a selected one of said resistors to an output terminal of said bridge; an electric motor commonly driving said first and second means; a source of potential having plural terminals at respective diflFerent potentials; and second selector switch means selectively operable to connect said motor to a selected one of the terminals of said last-named source of potential; said first and second selector switch means being interconnected for conjoint operation to control the speed of operation of said first and second means in ac cordance with the resistance setting of said A.C. bridge.

References Cited UNITED STATES PATENTS 3,207,896 9/1965 Meaney -77.5X 3,224,355 12/1965 Thomiszer 9577.5

JOHN M. HORAN, Primary Examiner.

US. Cl. X.R. 9589

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