EP0061596B1 - Printing machine with adjusting motors - Google Patents

Abstract

A printing press, in particular an offset printing press comprising a plurality of individually operable setting motors, in particular for adjusting the inkfilm density profile, each setting motor being connected to a pick-up generating electric signals characteristic of the actual position of the setting motor at any given moment (actual values) comprises an electronic comparator arrangement (35, 44) which is supplied with the actual values and, in addition, desired values for the position of the individual setting motors (9) and which repeatedly scans the actual values sequentially in a cyclical time sequence and compares each actual value with the related desired value to form a setting signal for operation of the associated setting motor in the forward or reverse direction when a given positive or negative minimum deviation is exceeded. The setting signals are fed to a switching arrangement (52) designed to cause the respective setting motor to be stopped or driven at a pre-determined speed in the sense of rotation determined by the last setting signal until the next signal is received. Thus it is rendered possible to easily control a plurality of setting motors.

Description

The invention relates to a printing press according to the preamble of claim 1. Such a printing press is known from DE-A-2401 750.

In the known printing press, when a setting process is to be initiated, the comparison device determines the deviation between the target values and the respective actual values and stores the determined differences in a counter assigned to the respective servomotor. While the servomotors are running, the individual counters are counted down by voltage pulses obtained from an alternating voltage, and as soon as they have reached the counter reading 0, the assigned servomotor is switched off. If a new actuating process is initiated at a later point in time, the comparison device again scans the actual values cyclically, resets the counters and initiates the actuating motors again.

The number of servomotors required in a printing press can be very large. Thus, in the case of an offset printing machine from the applicant, 32 adjusting cylinders are mounted eccentrically rotatably mounted in a row for setting the ink layer thickness profile in a row with a single inking unit. With a machine for multi-color printing with 6 printing units, 192 servomotors are therefore required for setting the different ink layer thickness profiles of the different printing inks.

DE-C-1 231 339 discloses a method for automatic register control, in particular for multi-color rotary printing presses, in which, when a register error exceeds a predetermined threshold value, a memory level is set which gives an adjustment pulse for the servomotor The memory level is not reset on the basis of a subsequent measurement, but when the counter determining the register deviation has been counted down by a preselectable frequency. Therefore, the servomotor may have been switched off before the next scan is carried out -3930447 describes a control device for densitometer measuring heads, which are arranged laterally adjustable by means of servomotors above printed sheets of paper to be measured.The desired position is entered into a register by a computer, and the register content is converted into a by a digital-to-analog converter analog size converted which is fed to an input of a comparator. The output of the comparator controls the servomotor. The actual position of the actuator is tapped via a potentiometer and fed to another input of the comparator. Such an arrangement is provided for each of the measuring heads.

From US-A-4193345 an adjusting device for the ink layer thickness profile of a printing press is known, in which the individual servomotors are connected to actual value transmitters designed as potentiometers. The wiper of the potentiometer is connected to one input of a comparator and the wiper is also connected to the other input of the same comparator via a sample and hold circuit. The output signal of the comparator controls the servomotor. The end connections of the potentiometer are connected to a controllable voltage source in order in this way to be able to take into account environmental influences, for example influences of temperature on the viscosity of the printing ink, by changing the supply voltage of the potentiometer. The voltage on the grinder before a change in the supply voltage is stored in the sampling and holding circuit, then the supply voltage is changed, and the servomotor now runs until the voltage on the grinder has reached the original voltage value of the grinder again. The arrangement described is provided for each individual servomotor.

The invention has for its object to design a machine of the type described above with relatively simple means so that the servomotors automatically reach the target positions specified for them.

This object is achieved according to the invention by the mercurals specified in the characterizing part of claim 1. The time interval between two successive scans of the same encoder by the comparison device is so short that the angle of rotation of the servomotor, including its stopping distance, which it still travels after being switched off, is at most half the tolerance angle, i.e. the angle by which the actual position of the motor may deviate from the theoretical target position in both directions of rotation, so that this deviation is still considered admissible for the application in question. If this scanning speed is correctly dimensioned taking into account the speed of the motor, the motor always comes to a standstill within the tolerance range when the actual value is scanned. The motor can therefore not exceed the tolerance range, and therefore there is the advantage that it is not necessary to change the direction of rotation of the motor several times until it has reached its desired position. Another advantage is that the comparison device can be constructed very simply because it does not have to determine the size of the deviation of the actual position of the motor from its target position that is present with each scanning operation, but only whether the motor is inside or is outside the tolerance range described above, and for this reason it is not necessary to determine and transmit data that represent the size of this deviation, but only the above-mentioned data, namely the control signals for forward run, reverse run and standstill. The invention can also be used to adjust the wet layer thickness, e.g. B. be used by means of actuating cylinders, as well as for setting the ink lifter. In the machine according to the invention, a manual control as described at the beginning can also be provided. During the setting process, servomotors that are assigned to different printing units can run simultaneously.

So that the actuating motor can be switched off with as little delay as possible, the actuating signals determined by the comparison device are expediently fed to the switching device immediately.

In one embodiment of the invention, an electronic memory for storing the steep signal is assigned to each servomotor in the switching device. A single flip-flop is not sufficient for the control signal to be able to assume three different values, and therefore two flip-flops are provided for each memory in the later exemplary embodiment.

The comparison device can be directly connected to each switching device assigned to a servomotor, but in one embodiment of the invention it is provided that the comparison device generates with each actuating signal an address signal that is assigned to the servomotor that has just been scanned, that the address signal is fed to an address decoder circuit. which supplies the control signal to the addressed memory, which is assigned to the corresponding servomotor, for storage. This embodiment allows a relatively low outlay in terms of circuit technology, in particular in the case of the large number of servomotors, as are present in the printing machines described above.

To change the direction of rotation of DC motors, it is known per se to switch them in a half-bridge circuit or in a full-bridge circuit. In the first case, one connection of the armature is constantly connected to a fixed potential, which is to be referred to as ground, and the other connection is connected to a positive or negative potential, depending on the desired direction of rotation. in the case of full-bridge switching, the two connections of the armature are connected to different polarities, and the polarity of both connections is reversed to change the direction of rotation.

In order to be able to operate servomotors in a half-bridge circuit or in a full-bridge circuit with one and the same electronic circuit, it is provided in one embodiment of the invention that the address decoding circuit can be switched over depending on an operating mode signal which is supplied to it and which represents two possible operating modes (half-bridge circuit, full-bridge circuit). in such a way that only one memory is assigned to one address in one mode (half-bridge circuit), and two memories are assigned to one address in the other mode (full-bridge circuit), which then store signals such that the servomotor in question turns on for forward and reverse operation its anchor terminals are supplied with different potentials. In general, this operating mode signal is set once by the manufacturer and can therefore be formed by a fixed potential. The arrangement is expediently such that this operating mode signal only fixes the address decoding circuit with regard to a small number of outputs of the switching device to a specific type of decoding, for example for only two outputs (two half-bridge circuits or a full-bridge circuit can optionally be implemented here), or for four outputs (four half-bridge circuits or two full-bridge circuits are possible here). It is possible to operate servomotors in a printing press, partly in full bridge circuit, partly in half bridge circuit.

In one embodiment of the invention, the comparison device contains an analog comparator for comparing the target values and actual values. In another embodiment, the comparison device contains a digital comparator for this purpose; this can essentially be formed by a subtractor.

In one embodiment of the invention, a brake logic circuit is provided which, when the control signal for standstill is present, generates a control signal for a connected power stage with switches in full bridge circuit, which controls two switches connected to the same pole of the motor supply voltage source. This can prevent the servomotor from running too long, which also depends on variables that are difficult to determine and therefore can only be calculated inaccurately, where this is necessary. This braking device can be switchable as a function of the above-mentioned operating mode signal, so that, as in the later exemplary embodiment, the braking device is only effective with a full bridge circuit.

The servomotors for a printing machine described above require a current which can be approximately up to 0.5 A per servomotor. Did you want the above mentioned z. B. 192 servomotors all start at the same time, this would require such a large total current in the case of the parallel connection in question that the power supply unit required for this would be uneconomically large and expensive, especially considering the running time of the servomotors of only a few Hours a year. In the known printing press described above, generally only a few of the servomotors run simultaneously.

In order to keep the total current required by the servomotors low, in one embodiment of the invention a control device is provided behind the memory, which supplies the electrical energy for driving the servomotors in succession to only one of a plurality of predetermined groups of the steep motors during a predetermined period of time.

This could be done in such a way that if a predetermined number, for example eight, of the 192 servomotors mentioned above, the drive energy is made available until the setting process has ended, the next eight servomotors are then supplied, etc., if desired is that a smaller tent passes between the actuation of the first servomotor and that of the last servomotor than it passes in the application just described, it is also possible, for example each of the groups of eight motors in each case, for example, for 0.5 s with current to supply, and then the next group and so on. It would also be possible to make the time in which the servomotors of a group are each supplied with energy considerably shorter, in particular also shorter than the time between two consecutive 'scans' of an encoder. Such a relatively quick keying of the energy supply can prove to be expedient if, in the case of a specific printing press, the servomotors run too fast in relation to the scanning speed of the comparison device, so that it is desirable to reduce their speed without at the same time the torque applied by the servomotors reduce significantly. This last-described mode of operation is also considered to fall under the invention described in claim 1, because this clocking of the energy supply does not influence the reliable operation of the invention, in particular the phase relationship of the clocking of the energy supply has relative to the sampling of the actual values of the individual servomotors no influence on the functional safety of the machine according to the invention.

In one embodiment of the invention, which can be implemented in particular in connection with the control device just described, and which can, but need not be, in particular with the selection of differently high speeds of the servomotors just described, it is provided that the comparison device for determining the exceeding of several differently large minimum deviations is formed by the actual values, and that a switchover device is provided which, at the beginning of a setting process, allows predetermined servomotors to run at a first predetermined speed, these servomotors being stopped when the value falls below a first minimum deviation, and that Switching device then lets these servomotors run at a lower speed than the first speed and switches the comparison device to a smaller deviation than the first minimum deviation. First there is a rough adjustment of the servomotors with a large tolerance range (minimum deviation) corresponding to the relatively high speed, and then the minimum deviation can then be chosen smaller due to the reduced speed of the motors and with this fine adjustment the servomotors can then be set to the desired position be positioned. The advantage here is that especially when setting all the servomotors of the machine for the first time, the setting process can be accelerated compared to those embodiments in which the servomotors can run at only a single speed. The arrangement can be made in the simplest case so that the switching of the servomotors to the reduced speed only takes place when all the servomotors that can run at the increased speed described have been stopped when the temperature falls below the first minimum deviation. In general, it should be expedient to run at least all those servomotors that have a relatively large adjustment range in the manner described at different speeds. The arrangement can expediently be such that not all servomotors run at the same speed at the same time, but, for example, only at most 16 servomotors each, so that the current consumption from a power supply device remains limited to relatively low values, as has already been explained above. The reduced speed can be brought about by the timing described above.

Despite the arrangement of the invention, which is in principle quite simple, the control of 256 servomotors, for which the circuit can be expediently designed, requires a considerable amount of logic circuitry to switch through the control signals to the individual servomotors.

In order to keep the number of components and thus the number of connections to be made on printed circuit boards as small as possible and thereby minimize the susceptibility to faults, one embodiment of the invention provides that the switching device contains at least one integrated circuit which has: Depending on the Control signals controllable power levels for connecting at least two servomotors, at least one address input for addressing the power levels, at least one data input for the control signals and at least one memory device for each power level for storing the control signals. Preferably points the integrated circuit has power levels for connecting a total of four servomotors in a half-bridge circuit or two servomotors in a full-bridge circuit; This embodiment can still be implemented without difficulty taking into account the external connections present in conventional housings for integrated circuits and the power loss. Protection is also claimed for the integrated circuit alone.

The integrated circuit is advantageous in bipolar technology, e.g. B. 1 ² L, or MOS technology. These techniques allow logic circuits and power stages to be implemented on the same die.

Further embodiments of the invention characterized in the claims create a possibility for effective braking of the servomotors and an adaptation of the control levels of the power stages to the signal levels occurring in the logic circuit.

• Figur 1 eine vereinfachte schematische Darstellung einer erfindungsgemäßen Druckmaschine,
• Figur 2 ein schematische Darstellung eines mit einem Stellzylinder gekoppelten Stellmotors,
• Figur 3 ein Prinzipschaltbild der gesamten Schaltungsanordnung für die Abtastung der Ist-Werte und die Steuerung der Stellmotoren.
• Figur 4 das Logikschaltblld einer in Fig. 3 verwendeten integrierten Schaltung,
• Figur 5 schematisch den AnschluB von vier Stellmotoren in Halbbrückenschaltung an eine integrierte Schaltung nach Fig.4,
• Figur 6 schematisch den AnschluB von zwei Stellmotoren in Vollbrückenschaltung an eine integrierte Schaltung nach Fig.4,
• Figur 7 eine Vollbrückenschaltung,
• Figur 8 ein Prinzipschaltbild einer Schaltungsanordnung, die zu Fig. 3 eine digitale Vergleichseinrichtung aufweist.

Embodiments of the invention are described and explained below with reference to the drawing. Show it :

• FIG. 1 shows a simplified schematic illustration of a printing press according to the invention,
• FIG. 2 shows a schematic illustration of a servomotor coupled to an actuating cylinder,
• FIG. 3 shows a basic circuit diagram of the entire circuit arrangement for sampling the actual values and for controlling the servomotors.
• FIG. 4 shows the logic circuit of an integrated circuit used in FIG. 3,
• FIG. 5 shows schematically the connection of four servomotors in a half-bridge circuit to an integrated circuit according to FIG. 4,
• FIG. 6 shows schematically the connection of two servomotors in full bridge circuit to an integrated circuit according to FIG. 4,
• FIG. 7 shows a full bridge circuit,
• FIG. 8 shows a basic circuit diagram of a circuit arrangement which has a digital comparison device for FIG. 3.

1 shows a side view, partially broken off, of an offset printing press 1 with eight printing units, with five of the printing units not being visible. In one of the machine parts visible in FIG. 1, some parts of a printing unit 8 are shown. The printing unit has a plate cylinder 2, which carries the printing plate and cooperates with the blanket cylinder 3, which transfers the printing ink to the paper to be printed, which runs between the blanket cylinder 3 and an impression cylinder 4. From the associated inking unit, only the ink metering box 5 with duct 6 is visible. At the lower area of the ink metering box 5 there is a divided ink knife 7, which consists of a series of actuating cylinders 15 (FIG. 2), each of which is connected to a servomotor 9. The printing unit 8 is also assigned a dampening unit 11 which has a water tank 12. Numerous other devices, in particular rollers for transporting the printing ink and water, and transport rollers are not shown for the sake of simplicity.

2 shows in simplified form the adjustment mechanism for one of the actuating cylinders 15 of the divided color knife. The servomotor 9 designed as a direct current motor drives a shaft 16 to which a potentiometer 17 is coupled. The shaft 16 carries at its end a threaded section 18 on which an adjusting piece 19 is screwed, which is connected via a link 20 to a lever 21 rigidly connected to the actuating cylinder 15. The lower base of the ink metering box 5 is formed by a plastic film 22, and depending on the position of the adjusting cylinder 15 having an eccentric twist 14, this plastic film 22 is pressed more or less close to the outer surface of the duct 6, thereby forming a more or less thick gap 23 through which the ink can reach the lower area of the duct roller. The ink is then removed from other rollers of the inking unit in a manner not shown. The adjustment cylinder 15 is thus displaced by a displacement of the adjustment piece 19 as a result of a rotary movement of the servomotor 9. Two of the electrical connections of the potentiometer 17 are connected to a voltage source, and the wiper of the potentiometer 17 is led out via a third line. The potentiometer 17 thus allows the respective position of the actuating cylinder 15 to be measured electrically precisely. 32 actuating cylinders 15 are assigned to each of the printing units of the printing press 1, the press 1 therefore has a total of 256 actuating cylinders and the same number of actuating motors 9.

3 only two of the 256 potentiometers 17 are shown. In the upper one, the mechanical actuation by the servomotor 9 is indicated by a dashed connection. Each of the potentiometers 17, which provides an actual value for the position of the servomotor 9 and thus of the actuating cylinder 15, is assigned a potentiometer 30, the voltage on the grinder of which represents the desired value of the position of the steep motor 9. In the simplest case, the wiper of the potentiometer 30 can be adjusted by hand. Instead of a potentiometer 30, any other adjustable memory for voltage values can also be used, in particular also a digital memory for digital values of the voltage, which is followed by a digital-to-analog converter, at the output of which a DC voltage corresponding to the stored digital value is generated.

An eight-digit binary counter 35 is provided, the counting input of which 36 pulses are supplied at regular intervals by a clock generator. The respective counter reading appears at outputs 37 as a binary number. 256 different meter readings are possible. The binary number appearing at the outputs 37 forms an address for the individual potentiometers 17. A first decoding circuit 38 is provided, de Ren inputs are connected to the outputs 37. The first decoding circuit 38 has 256 outputs. Each of the pairs of a potentiometer 17 and a potentiometer 30 assigned to each other is assigned a switch 40 which is connected to exactly one output line of the first decoding circuit 38. The upper switch 40 in FIG. 3 is connected to that output of the first decoding circuit 38 which assumes a predetermined potential when the counter 35 shows the counter reading 255, the lowermost switch 40 in FIG. 3 is connected to that output which has the said Potential assumes when the counter 35 shows the counter reading 0. Only one of the outputs of the first decoding circuit 38 has this potential, and this causes a double-pole switching of the switch 40, so that the wiper of the assigned potentiometer 17 is connected to a line 42 and the wiper of the assigned potentiometer 30 is connected to a line 43 is connected. These lines 42 and 43 are connected to the signal inputs of a comparator circuit 44, which contains white individual comparators 45 and 46, each of which emits a positive output signal representing the logic value 1 when the signal supplied to its lower input on the left side is higher is the signal applied to its upper left input. The voltage supplied by the wiper of the potentiometer 30 to the line 43, which represents the exact desired value of the rotational position of the associated servomotor 9, is increased somewhat via an adjustable resistor 47, the other end of which is connected to positive voltage, this increase in voltage permissible deviation of the rotary position of the servomotor 9 from the target value corresponds upwards. This raised voltage value is fed to the upper input of the comparator 45. A voltage value is supplied to the lower input of the comparator 46, which is reduced by an amount that is twice the deviation compared to the voltage value supplied to the upper input of the comparator 45 by means of an adjustable resistor 48, which forms a voltage divider with a resistor 49 connected to ground corresponds to the rotary position of the servomotor 9 from the setpoint. Line 42 is connected to the lower input of comparator 45 and the upper input of comparator 46. A positive signal therefore appears at the output of the comparator 45 if the voltage on the line 42 is greater than a voltage which corresponds to the nominal value of this voltage plus the tolerance set by the resistor 47, and a positive signal then appears at the output of the comparator 46 if the voltage on line 42 is lower than the target voltage minus the allowable deviation from the target value. In all other cases, the output voltages of the comparators are 45 and 46 0 V.

The six most significant outputs of the counter 35 are fed to a second decoding circuit 50 with 64 outputs, only one of these outputs assuming a low potential depending on the counter reading of the counter 35, which serves as a chip selection signal for selecting one of 64 integrated circuits 52. The two least significant outputs of the counter 35 are fed to two address inputs of each of the integrated circuits 52. The outputs of the comparators 45 and 46 are also fed via lines 51 and 53 to two data inputs of each integrated circuit 52. Each integrated circuit 52 has four outputs, which allow the connection of four servomotors 9 in a half-bridge circuit or two servomotors 9 in a full-bridge circuit.

The logical circuit diagram of the integrated circuit 52 is shown in FIG. It contains inverters, AND gates, NAND gates, NOR gates and flip-flops, which are represented by the known symbols, and also four power stages 56 to 59, which are each of the same design. All connections for the operation of the logic circuits are shown on the left edge of FIG. 4. A reset input R is used to reset all flip-flops when the power supply for the illustrated electronic circuits is switched on, in order to ensure defined output states. The inputs AO and A1 are supplied with the address signals supplied by the two least significant outputs of the counter 35. Two negated chip selection inputs CS1 and CS2 are provided; one of these inputs is connected to exactly one of the outputs of the second decoding circuit 50, the other of these two inputs is set to 0 V. If a chip selection signal with a low potential (ground) occurs, the condition CS1 = 0 is thus fulfilled and the addresses supplied to the inputs AO and A1 can be evaluated. Having two chip select inputs can often simplify addressing. Two further connections (U, GND) are provided for the voltage supply of the logic circuit. An FZIRE input is used to switch between half-bridge and full-bridge circuits. If this input is connected to ground, i.e. logic 0, then four stepper motors can be connected in half-bridge circuit to the output stages 56 to 59.If the input FZ / RE is connected to a positive voltage of 5 volts in the example, 56 and 57 can be connected to the output stage pairs on the one hand and 58 and 59 on the other hand each a servomotor connected in full bridge circuit.

The control signals appearing on lines 51 and 53, which can also assume the logical values 0 and 1, are fed to the data inputs D + and D-. Two equal inputs P and SP make it possible to block the output stages 56 to 59 without influencing the memory, e.g. B. for pulse operation.

• - 15 V. Die Leistungsstufen 56 bis 59 haben jeweils zwei Ausgänge, wobei der jeweils obere die positive Versorgungsspannung von + 15 V und der jeweils untere die negative Versorgungsspannung - 15 V an einen angeschlossenen Steilmotor wahlweise durchschalten kann.

Connections for a positive and negative supply voltage for the servomotors to be connected are drawn in at the bottom right of FIG. 4; in the exemplary embodiment these are the voltages of + 15 V and

• - 15 V. The power levels 56 to 59 each have two outputs, whereby the upper one can switch through the positive supply voltage of + 15 V and the lower one the negative supply voltage - 15 V to a connected high-speed motor.

The integrated circuit 52 contains several functional units. An operating mode-dependent pressure decoding 60 is provided which, depending on whether the integrated circuit 52 is switched to half-bridge circuit or full-bridge circuit, either assigns exactly one of the power stages 56 to 59 to one specific address supplied to the connections AO and A1 or one of the pairs 56, 57 or 58, 59 of the power levels. A data interlock 61 ensures that only one of its two outputs can assume the value logic 1, or that both outputs have the value logic 0. The data latch 61 provides security against interference in the event that the logic 1 signal occurs simultaneously on the lines 51 and 53 for some reason. An operating mode-dependent data decoding 62 carries the data, namely the control signals, depending on whether the integrated circuit 52 is switched to a half-bridge circuit or a full-bridge circuit, in each case only to the memory assigned to a single power stage or to a pair of power stages 56, 57 or 58, 59 assigned memories. The eight flip-flops 54, 55 provided are combined into a storage unit 63 by a dashed frame. Two of the flip-flops are one. Power amplifier assigned, this is also indicated by dashed lines. Each of the flip-flops 54, 55 has a clock input T, a reset input R, a data input D and a non-inverting and inverting output Q and Ó. The flip-flops 54, 55 are clock-controlled (latch) and store the information contained in them at the end of the clock pulse. During the application of the clock pulse, the memory content follows the input signal.

A functional unit pulse signal processing 64 evaluates the input signal fed to the inputs P and SP in order to block the power stages 56 to 59 in accordance with these signals. This pulse signal processing 64 is connected downstream of the memory unit 63 and causes a mutual locking of the output signals of the two flip-flops 54 and 55 assigned to an output stage. In the case of a full-bridge circuit, an operating mode-dependent braking logic 65 causes those pairs of power stages 56, 57 and 58, 59 which have no control signals for forward or reverse running of the respectively connected servomotor, the connections of the armature of the servomotor are at the same potential, in the example - 15 V. As a result, the armature of the servomotor is short-circuited and is therefore braked very quickly. If the armature is already at a standstill, undesired twisting of the armature, for example as a result of vibrations, is prevented.

The logic elements connected downstream of each pair of flip-flops 54 and 55, each of which together form a memory assigned to exactly one power level, and which are part of the pulse signal processing 64 and the operating mode-dependent braking logic 65, are connected in the same way in all cases. These are three NAND gates 91, 92, 93, a NOT gate 94 and an AND gate 95. The output of the NOT gate 94 is in each case connected to the upper input of the assigned power stage 56 to 59, that is to say the input E1 +, E2 + etc. connected. The output of element 95 is connected to the other input of the power stage. The input of link 94 is connected to the output of link 91. One input of link 95 is connected to the output of link 93, the other input to the output of link 92. The inputs of link 93 are to the outputs of links 91 and 92 and to the FZ / RE input of integrated circuit 52 connected. The inputs of the gate 91 are connected on the one hand to the output of a NOR gate 96, the inputs of which are connected to the control inputs P and SP of the integrated circuit 52, the further inputs of the gate 91 are connected to the non-inverting output of the flip-flop 54 and the inverting one Output of the flip-flop 55 connected. One input of the link 92 is again connected to the output of the link 96, the other two inputs are connected to the inverting output of the flip-flop 54 and the non-inverting output of the flip-flop 55.

The brake logic 65, which is formed by the elements 93, 94 and 95, ensures that when the memory contains the flip-flops 54 and 55 with the logical values 0; 0 in the case of a half-bridge circuit at the inputs of the assigned power stages 56 to 59, the signals 0; 1 are present and thus the two outputs M + and M- of this power level are switched off, whereas with a full bridge circuit with the same memory content 0; 0 at the inputs of the two mutually assigned power levels, for example 56 and 57, the logic level 0 is everywhere, so that the output M- is at the negative motor supply voltage at both power levels, so that electrical braking of the motor is possible as a result.

In the case of half-bridge circuits, the following combinations of the address signals supplied to the connections A1, AO are each assigned the power levels specified behind them: 0; 0 to 56, 0; 1 in 57, 1; 0 to 58, 1; 1 to 59.

In the case of full bridge switching, the following address signals are fed to the inputs A1, AO len assigned the pairs of power levels specified behind: 0; 0 to 56 and 57, 1; 1 to 58 and 59. With fixed wiring, therefore, only a single address line is required. For the following combinations of the control signals supplied to the data inputs D + and D-, it is specified whether they result in the motor connected to the respective power stage or the power stage pair addressed to a standstill, or cause a forward or reverse run. The direction of rotation of the motor which results when the respective power stage supplies a positive voltage to the motor in the case of a half-bridge circuit should be defined as the forward run, and should be defined as a forward run in the case of a full-bridge circuit when the upper of the two power stages in FIG. to which the motor is connected supplies positive voltage to it. The information applies to full and half bridge switching. 0; 1 for forward run 1; 0 for reverse running; 0; 0 for standstill.

5 shows in a simplified manner how four servomotors 9 can be connected to an integrated circuit 52 in a half-bridge circuit. The two outputs of each power stage 56, 57, 58, 59, which are designated M1 +, M1- for example at power stage 56, are connected to one another, and a servomotor 9 is switched on between the connection point and ground. The two outputs belonging to each of the power stages 56 to 59 could also be connected to one another within the integrated circuit 52. However, they are brought out so that a servomotor that is only operated in one direction of rotation or another consumer can be connected to each of the outputs if required. However, it is then appropriate to do so. ensure that the two outputs can be controlled independently of each other. In the arrangement according to FIG. 5, the logic input FZ / RE is connected to ground, that is to say to logic 0.

6, the logic input FZ / RE is at + 5 V, this voltage value represents the logic level 1. The two outputs belonging to one of the output stages 56 to 59 are in turn connected to one another and a servomotor 9 is between the common ones Outputs of power level 56 and 57 switched on, another servomotor 9 between the interconnected outputs of power level 58 and power level 59.

7 shows the circuit diagram of an exemplary embodiment of power stages which form a full bridge circuit. These power levels can form the power levels of the integrated circuit 52, and in individual cases changes due to the integrated circuit technology may be necessary. In the following it is assumed that the two power stages 56 and 57 of the integrated circuit according to FIG. 4 are shown in FIG. 7, and therefore in FIG. 7 they are also the same designations for the signal inputs E1 +, E2 +, E2- and the outputs Mi +, M1-. M2 +, M2- used. 7 are the connections for the positive and negative supply voltage for the motor, as well as the positive supply voltage for the logic (+ 5 V) and the ground connection for the logic (GND).

The circuit diagram for power level 57 is completely the same as that for power level 56, and the corresponding components are also the same. A pnp power transistor 70 has its emitter connected to the positive motor supply voltage and its collector to the M1 + output. An npn power transistor 71 is connected with its collector to the output M1- and with its emitter to the negative pole of the motor supply voltage. Both collector-emitter paths are bridged by a diode 72, which is connected opposite to the polarity of the respective base-emitter diode. These diodes 72 serve to protect the transistors 70 and 71. In each transistor 70, 71 there is a connection between the base connection and emitter connection via a resistor 75 and 76, which are of the same size. The collector of an npn transistor 78 is connected to the base of transistor 70, the emitter of which is connected via a resistor 79 to the connection for the ground potential of the logic (GND). This connection is connected via a voltage source 80 to the base of the transistor _" 78, which is also connected via a resistor 81 to the connection E1 +. In the example, the voltage source 80 is formed by a series connection of four diodes.

The base of transistor 71 is connected to the collector of a pnp transistor 84, the emitter of which is connected via a resistor 85 to the connection for the positive supply voltage for logic, which is connected to the base of transistor 84 via a voltage source 86 which is also formed by a series connection of four diodes. The diodes of the voltage sources 80 and 86 are each poled in the same direction as the base-emitter diode of the associated transistor. In conjunction with the resistors 81 and 82, these diodes 80 and 86 maintain the base voltage of the transistors 78 and 84 even when the values of E1 + are different. E1-. if this z. B. assume values of up to + 10 V, almost constant and thereby limit the base current and thus limit the power loss of transistors 78 and 84. The base of transistor 84 is connected via a resistor 82 to terminal E1-. The signals occurring at the input terminals E1 + and E1- as well as E2 + and E2-, which are output signals of the operating mode-dependent brake logic 65, can assume the levels + 5 V and 0 V based on logic ground. If the two logic inputs E1 + and E1- are supplied with the same input signals with the value logic 0, i.e. 0 V, see above 7 the upper power transistor 70 is blocked and the lower power transistor 71 of the power stage 56 is switched through, the connection point between the outputs M1 + and M1- is therefore due to the negative motor supply voltage of -15 V. The two inputs E1 + and E1- Signal logic 1 supplied, i.e. a voltage of + 5 V, transistor 70 is switched on and transistor 71 is blocked and the connection point of outputs M1 + and M1- is at + 15 V.

If a voltage of 0 V is supplied to the input E1 + and a voltage of + 5 V to the input E1-, the outputs M1 + and M1- are voltage-free since both transistors 70 and 71 are blocked.

The state that a voltage of + 5 V is supplied to the input E1 + and a voltage of 0 V to the input E1- is inadmissible in the circuit shown, in which the two transistors 70 and 71 are directly connected to one another, because in this If the motor supply voltage were short-circuited. This inadmissible state is prevented by the locking effected by the pulse signal processing 64.

In order for the servomotor 9 in FIG. 7 to be driven in the forward direction defined above, the voltages + 5 V and the voltages 0 V must be supplied to the signal inputs E1 + and E1- and the signal inputs E2 + and E2-. For reverse running the voltage values just mentioned have to be exchanged.

So that the servomotor 9 is stopped as quickly as possible, not all the transistors 70 and 71 of both power stages 56 and 57 are blocked to switch off the servomotor 9, but rather it is connected to the input terminals E1. E2 of the two power stages 56 each has the voltage 0 V applied, so that the negative supply voltage is at the two armature connections of the servomotor 9 which are connected to the outputs of the power stages 56 and 57, these two connections of the armature are therefore short-circuited. The armature winding therefore generates a current which, when the servomotor 9 is running in the forward direction, has the direction designated by reference numeral 89- in FIG. 7. This current can flow through the collector-emitter path of the transistor 71, since this is controlled to be conductive at its base. With a customary dimensioning of the base voltage of the transistors 71 of the two power stages, however, the current could not flow through the transistor 71 of the power stage 57 because this is an npn transistor. In this case, the current flows through the diode 72 connected in parallel with this transistor. Since a voltage of approximately 0.7 V to 1 V drops across this diode, an armature current flows in the motor 9 only until its terminal voltage has just been mentioned If the voltage drops, the motor is no longer braked electrically, but only by the frictional forces that it has to overcome.

According to the invention, however, the resistor 85 in both output stages 56 and 57 is so small that the transistor 84 supplies the base of the transistor 71 with a base current which is at least about 30 times as large as is required for the normal switching operation of the transistor. This makes it possible to also operate the transistor 71 inversely, this inversely operated transistor only causing a voltage drop of approximately 50 to 100 mV. The servomotor 9 is therefore electrically braked to a considerably lower terminal voltage and therefore comes to a standstill considerably faster than if the armature current could only flow through the diode 72 during the braking process within the power stage 57. In the direction of the armature current shown in FIG. 7, it would not be necessary for the transistor 71 of the power stage 56 to be supplied with the aforementioned high base current, but the dimensioning of the resistors 85 described makes it superfluous to each of the transistors 71 if necessary switching on a higher base voltage and thereby simplifying the circuit. It goes without saying that the arrangement could also be such that the two transistors 71 are blocked for braking the motor 9 and the two transistors 70 are controlled to be conductive; these latter transistors would then have to be supplied in the manner described with the base current which is higher than in normal operation. In the exemplary embodiment described, however, the resistors 79 are larger than the resistors 85, so that the transistors 70 can only conduct a current flowing from the emitter to the collector.

In the case of a special servomotor 9, a shutdown time of 3 seconds resulted when the power supply was simply switched off. If this motor was operated on the circuit shown in FIG. 7, but the transistors 71 could not be operated inversely, the braking time by means of the diode 72 reduced the run-down time to approximately 0.5 seconds. Finally, in the circuit shown in FIG. 7, in which the transistors 71 are operated inversely in the manner described above, the run-down time was only 7.5 ms.

Another advantage of the circuit shown in FIG. 7 is that although it has to switch large positive and negative voltages compared to the logic levels, it has the level 0 V at one of its control inputs. The other control input receives a positive or a negative potential for switching depending on the circuit. In the example, the logic levels 0 V and + 5 V are used. This advantage applies to each of the two output stages 56 and 57 alone, each of which forms a half-bridge circuit when the servomotor 9 connecting the two output stages is removed in FIG. 7. Then a servomotor can be switched on between the connection point of the connections M1 + and M1- and a fixed potential, in particular ground. The advantage with these Half-bridge circuits lie in the fact that a positive or negative voltage can optionally be switched at their circuit output formed by the connection of the connections M1 + and M1-.

• Transistor 70 : BSV 16-16
• Transistor 71 : BSX 46-16
• Transistor 78 : BCY 59/X
• Transistor 84 : BCY 79/VIII
• Dioden 72 : 1 N 4003
• Widerstand 81 : 2 kOhm
• Widerstand 82 : 6,2 kOhm
• Widerstände : 75, 76 : 82 kOhm
• Widerstände : 79, 85 : 82 kOhm
• Spannungsquellen 80, 86 : je 4 x Diode BAW 76

In the embodiment of FIG. 7, the following values apply to the individual components:

• Transistor 70: BSV 16-16
• Transistor 71: BSX 46-16
• Transistor 78: BCY 59 / X
• Transistor 84: BCY 79 / VIII
• Diodes 72: 1 N 4003
• Resistor 81: 2 kOhm
• Resistor 82: 6.2 kOhm
• Resistances: 75, 76: 82 kOhm
• Resistances: 79, 85: 82 kOhm
• Voltage sources 80, 86: 4 x BAW 76 diodes each

It is assumed that the described rapid braking of the servomotors 9 is not necessary in a printing machine for the ink zone control. These servomotors, which are used to adjust the ink layer thickness, can therefore be connected in a half-bridge circuit. A printing machine for multicolor printing also has setting devices by means of which a precise match of the individual prints applied by the different printing units, each with a different color, is ensured. These settings. directions are called registers. Since a very high setting accuracy is required here, it will generally be necessary to operate the servomotors that drive the registers in the manner described above in voli-bridge circuit in order to be able to brake these servomotors quickly. The terminal designation FZ / RE was chosen with regard to the terms color zone and register. The registers are generally adjusted by the printer during the printing process, but can also be done automatically.

In the exemplary embodiment, the cycle time, that is to say the time period which is available for the detection of the actual values by the comparison device and the forwarding of the control signals up to the power levels, is approximately 50 μs. The servomotors 9 are each operated in pulsed fashion via the pulse input P, the current flow time in the motor in the exemplary embodiment being 30 ms and the pause between two pulses being 270 ms. Different groups of servomotors are supplied with the current pulses at different times from each other.

In the exemplary embodiment, the time required for a servomotor to run through the entire adjustment range is 8 seconds. The entire adjustment range is divided into 256 intervals, which should be accessible individually. Each of these intervals or increments has a length of approximately 30 ms. During this time, the electronic device 600 described above can query the actual values, together with the corresponding determination of the steep signals. Since the printing press with eight printing units described above as an example requires around 24 additional servomotors for the registers, i.e. a total of 280 servomotors, in addition to the actuators for the ink zone setting, two inquiries are made for each servomotor within each of its individually approachable 256 increments. There is thus a high level of security against accidents which could occur because one of the queries is disturbed for some reason.

FIG. 8 shows an overall circuit which can be provided instead of the circuit arrangement shown in FIG. 3 and which has a digital comparison device. The actual values are also recorded here by the potentiometer 17, of which only two are shown, one for the actual value 1 and one for the actual value 256. Here, too, 64 integrated circuits 52 are provided, which additionally with the designations IS 1 (integrated circuit 1) to IS 64. Only four of these integrated circuits are shown in FIG. 8.

The analog signals for the actual values generated by the potentiometers 17 are fed to an analog multiplexer 120. A binary counter 135, which is advanced by a clock generator 136, has 9 counting stages and the same number of outputs 141 to 149. The signals appearing at the eight most significant outputs 142 to 149 are used as address signals, which are supplied among other things to address inputs of the analog multiplexer 120. The actual value selected by the address present in each case is fed from the analog multiplexer 120 to an input of an analog-digital converter 150 which converts this analog signal into a binary. Converts 8-bit information that are fed in parallel to a group of inputs 152 of a binary comparator 151. The analog-digital converter 150 also receives its start command for conversion from the least significant output 141 of the binary counter 135. Since the pulse repetition frequency appearing at this output 141 is twice as high as the switching frequency of the addresses appearing at the outputs 142 to 149, it is ensured that that between the generation of two successive addresses, the analog-to-digital converter 150 receives a start signal.

A second group 153 of inputs of the binary comparator 151 are supplied with digital setpoints from a digital setpoint memory, to which the address signals from the binary counter 135 are also fed and which in each case connects through the setpoint to the binary comparator that has just been switched through by the analog multiplexer 120 Value is assigned. The digital nominal values supplied to the inputs 156 of the nominal value memory 155 can be generated with the aid of an analog-digital converter from analog signals which are supplied, for example, by potentiometers. However, these target values can also be entered into the target value memory 155 by means of a keyboard or from a computer or from a data medium on which they are stored in binary form.

The binary comparator 151 is a subtracting circuit. It performs the subtraction of the signals fed to the inputs 152 from the signals fed to the inputs 153 whenever an output Data Ready of the analog-digital converter 150 outputs a signal to the binary comparator 151. Depending on the result of the subtraction, the binary comparator 151 then outputs an output 160 (if the signal at the inputs 152 was larger than at the inputs 153) or 161 (in the opposite case), assuming that the two values are the same have to distinguish the minimum deviation described at the outset, or the binary comparator 151 does not output an output signal. The outputs 160 and 161 are connected to the data inputs D + and D- of the integrated circuit 52. The two least significant bits of the address present at the analog multiplexer are applied to the address inputs AO and A1 of the integrated circuits 52 and thus cause a preselection of the output stages of the individual integrated circuits. The chip selection itself is carried out with the aid of a decoder 165 with 5 inputs and 32 outputs and with the aid of the most significant address bit. For this purpose, the 64 integrated circuits 52 are divided into two groups IS1 to IS32 and IS33 to IS64.

An integrated circuit of each group receives the CS 2 signal from decoder 165. One of the groups 1 to 32 or 33 to 64 is then selected by the most significant AdreBbit, which in the first group is directly inverted to the CS1 inputs and in the second group by a non-song 170 to the CS 1 -Inputs is created. As a result, exactly one of the integrated circuits 52 is selected. The integrated circuits 52 in FIG. 8 are the same as those described with reference to FIG. 4. has been.

As far as details of the circuit, especially in Fig. 4, have not been described, reference is made to the drawing.

Claims (20)

1. Printing machine, preferably offset printing machine (1), in which a plurality of individually switchable servo motors (9) is provided, preferably for adjusting the ink layer thickness profile, each servo motor (9) being connected to a transmitter (17) which generates electric signals (actual values) which are characteristic of the respective actual position of the servo motor (9), an electronic comparing device (35, 44) being provided which is supplied with the actual values and also with the nominal values for the position of a servo motor (9) and which compares the actual value with the nominal value and, as a function of the result of the comparison, causes the servo motor (9) to run in the forward direction or to run in the reverse direction or to stand still, the comparing device (35, 44) being supplied with the actual values and nominal values of the individual servo motors (9) and the comparing device successively in time and cyclically repeatedly interrogating the actual values, characterised in that the comparing device (35, 44) repeatedly interrogates the actual values during an adjusting operation of a servo motor (9), that the comparing device (35, 44) generates servo signals for the forward motion or the reverse motion of the associated servo motor (9) If a predetermined positive or negative minimum deviation is exceeded and otherwise generates a servo signal for the standstill of this servo motor (9) and that the servo signals are supplied to a switching device (52) which is constructed in such a manner that the respective servo motor (9) is driven at a predetermined speed of rotation in the direction of rotation determined by the respectively last servo signal allocated to it, or remains stopped, until the next servo signal allocated to it arrives.

2. Machine according to Claim 1, characterised in that in the switching device (52) each servo motor (9) is associated with an electronic memory (54, 55) for storing the servo signal.

3. Machine according to Claim 1 or 2, characterised in that the comparing device (35, 44, 135, 151) generates with each servo signal an address signal which is allocated to the servo motor (9) just sampled, and that the address signal is applied to an address decoding circuit (50, 60, 165) which supplies the servo signal to the memory (54, 55) associated with the corresponding servo motor (9).

4. Machine according to Claim 3, characterised in that the address decoding circuit (60) can be switched over as a function of an operating mode signal which is supplied to it and which represents two possible operating modes (half-bridge circuit, full-bridge circuit), in such a manner that in one operating mode (half-bridge circuit) an address is in each case allocated only one memory (54, 55) and in the other operating mode (full-bridge circuit) an address is allocated two memories (54, 55).

5. Machine according to one of Claims 1 to 4, characterised in that the comparing device (35,

44) is provided with an analog comparator (45, 46) for comparing the nominal values and actual values.

6. Machine according to one of Claims 1 to 4, characterised in that the comparing device (135, 151) is provided with a digital comparator (151) for comparing the nominal values and the actual values.

7. Machine according to one of the preceding Claims, characterised in that a braking logic circuit (65) is provided which, in the presence of the servo signal for standstill, generates a control signal for a connected power stage (56, 57) with switches (70, 71) in a full-bridge circuit, which signal renders conductive two switches connected to the same terminal of the motor supply voltage source.

8. Machine according to Claims 4 and 7, characterised in that the braking logic circuit (65) can be switched on by the operating mode signal for full-bridge circuit.

9. Machine according to one of Claims 2 to 8, characterised in that a control device is provided which is arranged following the memory (54, 55) and which supplies the electric energy for driving the servo motors successively in each case only to a part of the total number of the servo motors (9) during a predetermined period of time.

10. Machine according to one of the preceding Claims, characterised in that the comparing device is constructed for determining the fact that several minimum deviations of different magnitudes have been exceeded by the actual values and that a switch-over device is provided which at the beginning of an adjusting process lets predetermined servo motors (9) run at a first predetermined speed of rotation, these servo motors (9) being stopped if the actual value drops below a first minimum deviation and that the switch-over device subsequently causes these servo motors (9) to run at a speed of rotation which is smaller than the first speed of rotation and switches the comparing device to a minimum deviation which is smaller compared with the first minimum deviation.

11. Machine according to one of Claims 1 to 9, characterised in that the switching device contains at least one integrated circuit (52) which is provided on the same chip with at least one power stage (56, 57) for connecting a motor (9) and a control logic circuit (60 to 65) for controlling the power stage (56, 57).

12. Machine according to Claim 11, characterised in that the integrated circuit (52) is provided with the following : Power stages (56 to 59), which can be controlled as a function of the servo signals, for connecting at least two servo motors (9), at least one address input for addressing the power stages (56, 57), at least one data input for the servo signals, and at least one memory device (54, 55) for each power stage (56, 57) for storing the servo signals.

13. Machine according to Claim 12, characterised in that the integrated circuit (52) is provided with power stages (56, 57) for connecting a total of four servo motors (9).

14. Machine according to one of the preceding Claims, characterised in that it is provided with a power stage (56, 57) for a servo motor (9), the power stage (56, 57) being provided with four transistors (70, 71) in a full-bridge circuit, the collector-emitter paths of which are connected, on the one hand, to the terminals of a supply voltage source and, on the other hand, to terminals for the armature of the servo motor (9) and that the base terminals of two transistors (70 and 71) connected to the same terminal of the supply voltage source are supplied at least during the braking of the motor (9) with a base current which makes it possible to operate the transistors in inverse mode.

15. Machine according to Claim 14, characterised in that the transistors provided for inverse operation are supplied, for conduction in normal operation for forward motion and reverse motion of the servo motor (9), with a base current the magnitude of which is identical to the base current for inverse operation.

16. Machine according to one of the preceding Claims, characterised in that it is provided with a power stage (56, 57) for a servo motor (9), which stage is provided with two controllable switches (70, 71) which selectively switch through a supply voltage, which is positive or negative with respect to a reference potential, to a circuit output or they are both blocked.

17. Machine according to Claim 16, characterised in that for controlling the switches (70, 71), two transistors (78, 84) are provided, that the emitter of one transistor (78) is connected to a first fixed potential and the base of this transistor can be supplied with a voltage, which is positive with respect to the fixed potential, as a control signal, and that the emitter of the other transistor (84) is connected to a second fixed potential, which is positive with respect to the first potential, and the base of the other transistor (84) can . be supplied with a voltage, which is negative with respect to the second potential, as a control signal.

18. Machine according to Claim 17, characterised in that to the positive terminal of a supply voltage source for the servo motor (9) the emitter of a pnp transistor (70) is connected, the base of which is connected to the collector of an npn transistor (78) the base of which is coupled to a first control input and the emitter of which is coupled to a connection of a first fixed potential, that the emitter of an npn transistor (71) is connected to the negative terminal of the supply voltage source for the servo motor (9), that the base is connected to the collector of a pnp transistor (84) the base of which is coupled to a second control input and the emitter of which is coupled to a connection of a second fixed potential and that the collectors of the pnp transistor (70) and of the npn transistor (71) form the outputs of the power stage (56, 57).

19. Machine according to Claim 17 or 18, characterised in that voltages having the level of the first and second fixed potential are provided as control signals.

Images