EP0116850A1 - Microprocessor controlled solenoid plunger print system containing an opto-electronic sensor - Google Patents

Abstract

An infrared light barrier for detecting the movement of the armature is arranged on the part of a plunger armature magnet system facing away from the pressure point in a type wheel printer. The output signal of this light barrier is used for the time control of the submersible magnet system. For this purpose, there is a slot ruler on the armature of the plunger magnet system, the rectified edges of which are scanned via the infrared light barrier and the signals are then fed to a microprocessor system which controls the plunger magnet system.

Description

The invention relates to a submersible pressure system according to the preamble of claim 1.

Submersible magnet systems as a drive device for a print hammer in type printing devices or printing needles in mosaic printing devices are generally known in printing technology and have been used successfully. DE-OS 3 116 430 describes a hammer pressure device with a plunger magnet system containing a light barrier, in which an infrared light barrier for detecting the movement of the armature is arranged in the part of the plunger magnet system facing away from the printing point for a type wheel printer. The output signal of the light barrier is used for the time control of the submersible magnet system.

With the known plunger magnet system, the built-in optoelectronic sensor makes it possible to determine the exact position of the print hammer and thus to determine the movement variables of the print hammer according to location and time, in order to use these movement variables to control the print hammer.

One problem, however, is the influence of manufacturing tolerances and changing operating conditions on the acceleration and braking of the print hammer, which can lead to falsification of the pressure.

The object of the invention is to design a plunger anchor pressure system of the type mentioned at the outset in such a way that manufacturing tolerances and operating conditions which change over time cannot affect the impression process.

This object is achieved in a submersible pressure system of the type mentioned in the characterizing part of patent claim 1.

Further advantageous embodiments of the invention are characterized by the subclaims.

• Fig. 1 eine schematische Darstellung des erfindungsgemäßen Tauchankermagnetsystems in Ruhestellung, teilweise in Schnittdarstellung,
• Fig. 2 eine ausschnittsweise Darstellung des am Anker des Tauchankermagnetsystems angeordneten Schlitzlineals; mit den entsprechend bezeichneten Meßstrecken,
• Fig. 3 eine schematische Darstellung des Ausgangssignals, des optoelektronischen Sensors bzw. des Spulenstromes in der Erregerspule in Abhängigkeit von der Bewegung des Schlitzlineals und damit des Ankers beim Abdruck,
• Fig. 4 eine tabellenartige Darstellung der Zuordnung zwischen den gemessenen Ist-Werten der Durchlaufzeiten des Schlitzlineals und der zugeordneten digitalen Korrekturwerte die notwendig sind,um ausgehend von dem Ist-Wert der Ankergeschwindigkeit zu dem vorgegebenen Sollwert zu gelangen und
• Fig. 5 ist eine schematische Darstellung der Schaltungsanordnung zum Betrieb des Tauchankermagnetsystem.

An embodiment of the invention is shown in the drawings and is described in more detail below, for example. It shows

• 1 is a schematic representation of the plunger magnet system according to the invention in the rest position, partially in a sectional view,
• 2 shows a detail of the slot ruler arranged on the armature of the plunger magnet system; with the correspondingly designated measuring sections,
• 3 shows a schematic representation of the output signal, the optoelectronic sensor or the coil current in the excitation coil as a function of the movement of the slot ruler and thus the armature during the impression,
• 4 shows a table-like representation of the assignment between the measured actual values of the throughput times of the slot ruler and the assigned digital correction values which are necessary to arrive at the predetermined target value based on the actual value of the anchor speed and
• Fig. 5 is a schematic representation of the circuit arrangement for operating the plunger magnet system.

With the printing device shown schematically in FIG. 1 for a teleprinter or typewriter, a type wheel, not shown here, which is arranged opposite a platen roller, is actuated by means of a plunger armature printing system described in more detail below. The plunger armature pressure system consists essentially of an excitation coil 1, and a pressure hammer 2 serving as a drive element for the type wheel consists of a soft-magnetic armature 2/1 and a non-magnetic plunger 2/2. The print hammer 2 is guided in sleeves 3 and rests against a stop 5 under the action of a return spring 4 in the idle state shown. A sensor 6, in this case a photoelectric switching device, is arranged in the area of the rear part of the submersible pressure system, the photo path 7 (light beam) being arranged in the range of motion of a slot ruler 8 which is positively connected to the armature 2/1. The slot ruler has two cutouts 9.1 and 9.2, which have a rectangular shape and the edges of which are scanned via the photo section 7. The plunger armature magnet is controlled via a control circuit arrangement which can be configured, for example, in accordance with the block diagram of FIG. 5, wherein when the plunger armature magnet is energized, the armature 2 of the plunger armature magnet moves from its rest position into the printing position and after in a movement form shown in FIG the impression returns to its rest position without bounce. During the printing process, the slot ruler 7 is scanned via the optoelectronic scanning device 6 and the armature travel distances X1 to X3 shown in FIG. 2 are evaluated. When determining the Anchor paths were based on the knowledge that the sensitivity curve and thus the response threshold of the photoelectric sensor change over time, so that the switch-on and switch-off points shift relative to one another. If, for example, one were to scan two consecutive edges, the first edge representing a transition from the interruption of the photo section (dark) to an opening of the photo section (light) dark-light transition and the second edge a corresponding light-dark transition, would be If the sensor device ages while maintaining the operating speed of the slot ruler, the measured sampling times of the defined distances change. The result would be a fake change in anchor speed. For this reason, according to the invention, a follow-up scan with at least two similar (light-dark, light-dark; dark-light, dark-light) transitions is preferably carried out to determine the throughput time of the anchor path sections via the scanning device. This means that, as shown in FIG. 2, apart from the initial anchor path X1, all anchor paths X2 and X3 are limited by transitions of the same type. For example, the anchor path X2 through the edges K1, K3 and the anchor path X3 through the edges K3 and K5.

A typical impression process is shown in FIG. 3. The abscissa of all three diagrams of FIG. 3 shown one above the other denotes the time axis T. The upper diagram of FIG. 3 represents the path AW of the armature 2 from the rest position R to the print on the platen roller SW and the subsequent braking with return to its starting position R. Parallel to the ordinate AW of the diagram is the slot ruler with the corresponding ones scanned distances X1 to X3 shown. The middle diagram of FIG. 3, which shows the signal amplitude SA as a function of the time at the output of the optoelectric sensor 6, is assigned to the upper diagram, with the course of the armature as a function of the time when the impression is taken. The course of the excitation current over time during printing is shown below this diagram in FIG. 3.

The submersible armature pressure system is actuated via the circuit arrangement shown in FIG. 5, which contains a microprocessor MP (8048 Siemens) with a central unit and memory. The function and structure of this circuit arrangement will be described in detail later.

In the submersible anchor pressure system shown in FIG. 1, the movement of the slot ruler 8 is scanned with the aid of the optoelectronic sensor 6, and thus control signals are generated. These signals are fed to an electronic control system, which contains a microcomputer MP, and among other things. used to control the current in the excitation coil 1. In this way it should be achieved that the print hammer receives a certain kinetic energy (impression strength) regardless of manufacturing tolerances and external influences and is braked after the impression by a current pulse in order to avoid bounce i.e. to return to its basic position quickly and without making any noise. At the same time, the functionality of the printing system is monitored.

At certain times, for example when the device is switched on, when synchronizing, etc., the level of the sensor signal 6 is checked. This ensures that the pressure tappet works correctly in the basic position and / or the sensor. For this purpose In the basic position shown in FIG. 1, checks whether the photo section 7 of the sensor 8 is interrupted. If this is not the case, an error message is sent via the microprocessor MP, the function of which will be described in detail later.

With each printing process, the time TX1 required to run through the measuring section X1 is measured and compared with a stored target time. If the measured time TX1 is longer than the stored target time, an error message is given and the printout during a certain time e.g. Disabled for 1 second and then released again. If such an error occurs several times in succession e.g. occurs three times, there is no re-approval of the imprinter, but the printing system is blocked and the error is shown by a warning device not shown here. On the one hand, the functionality of the printing system, e.g. Broken wire, short circuit etc. are checked, on the other hand the printout cannot be prevented unnecessarily in the event of a temporary fault.

With each printing process, the time TX2 required to pass through the measuring section X2 is also measured. Each time TX2 is assigned a time TA after which the excitation current I is switched off. The relationship between the measured time TX2 and the time at which the excitation current is switched off is shown in table TB1 in FIG. 4. Therein, the values 1 to 20 in the column TX2 denote a sequence of actual values, stored in binary form in the microprocessor MP, of the actual values which have been found, as experience has shown, when passing through the armature distance X2; these values are in the form of binary code words which are only symbolically represented here (1 ... 20) saved in memory.

Associated with them is a second sequence of correction values stored as a sequence of binary code words, which are shown in column TA of table TB1. These correction values 1 to 20 of table TB1, column TA correspond to the course of the excitation current which is necessary in order to arrive at the specified target value based on the actual value of the armature speed. This is accomplished with the aid of the microprocessor and the circuit arrangement of FIG. 5. For this purpose, after determining the actual actual time TX2 and the assignment of the corresponding code word, for example code word 5 of table TX2, the correspondingly assigned code word 5 of column TA of the correction value is called and this correction value 5 of column TA of table TB1 is sent to the outputs of microprocessor applied, and then through the in more detail to be _-.. a shutdown of the coil current is effected I writing circuit arrangement of Figure 5, taken after a time TA with a correspondingly FIG illustrated steep falling edge 3 (bottom graph) Jurch this switching off the Coil current as a function of the measured throughput time of the armature distance / that the pressure ram achieves the desired.ki- regardless of tolerances, for example the fluctuating quality of the magnetic material. receives netic energy for printing. Different impression strengths to be determined can be achieved by different but also to be determined current strengths.

After each impression, the time TXB required to run through the measuring section X3B is also measured. A current ICB (table TB2, Fig. 4) is assigned to each time TX3. Here too, as previously described, the time TX3B corresponds to the actual times 1 to 20 defined in the form of code words (column 1, table TB2 of FIG. 4). They are again assigned in table TB2, Correction values 1 to 20 shown in column ICB. These correction values are assigned to the individual measured times so that the armature returning at different speeds is always braked as bounce-free as possible, ie as quickly as possible and without noise. This is achieved by adapting the excitation current (.Amplitude) of the brake pulse ICB in accordance with the measured throughput times TX3B. The determination of the basic brake current ICB is now followed by a phase of checking the speed when the armature returns to its basic position. This is achieved by measuring the throughput time of the armature path section X2 and determining a current IVB as a function of this measured throughput time TX2B, which current is applied to the excitation coil after the armature path section X2 has been passed through. This variable excitation current IVB depends on the armature speed measured when passing through the armature path section X2. If, for example, according to the upper diagram in FIG. 3, the dashed curve, the armature is too fast when returning to its starting position, which is the case, for example, if there is little friction or the material is poor, the braking current will be correspondingly higher IVB (dashed line curve lower diagram of Fig. 3) achieved that there is a soft braking. At high return speeds of the armature, it is therefore necessary to generate a short but strong current pulse, since there is little time left until the armature returns to its rest position and thus for its soft braking. If the armature is slow in its return in relation to the normal course of the curve (dotted representation in FIG. 3), a correspondingly lower but longer braking current IVB is required.

The selection of the braking current IVB or the switch-off time TAB, after which the braking current IVB is switched off and after which the braking current decays continuously according to an e-function, results from table TB3. Here, as previously stated, the sequence of code words in column TX2B denotes the actual values to be expected, whereas the sequence of code words IVB and TAB columns 2 and 3 of table TB3 denotes the corresponding correction code words, which correspond to the actual values of the column TX2B are assigned so that the desired smooth and bounce-free braking of the armature results.

The braking process can be corrected by the additional measurement process via the anchor path X2. A one-time measurement over the anchor path X3 would lead to inaccurate results, since this one-time measurement would not detect a change in speed as such and therefore the braking deceleration.

The current IVB does not become abrupt in order to allow the anchor to bounce against its system without bouncing. switched off, Sonder decays continuously and preferably after an e-function.

The circuit arrangement shown in FIG. 5 for operating the submersible anchor pressure system consists of a central microprocessor MP of type 8048 Siemens, which is controlled via a generally known printer controller DS, which is not described in detail here, and which is controlled by an optoelectronic sensor in this case a light barrier LS outgoing and supplied via a discriminator D3 appropriately transformed signals. A digital-to-analog converter DA is connected downstream of the microprocessor MP. His resistance Network from the evaluation resistors RB supplies an output voltage UA corresponding to the applied bit pattern of the code words, which is fed to a downstream current regulator as a setpoint. The current controller arrangement consists of an operational amplifier OP1 which is fed back via a capacitor C2, and a downstream semiconductor switching arrangement comprising the two switching transistors TS1 and TS2 with associated resistors R, the input of the excitation coil of the plunger armature pressure system and a free-wheeling diode D1 arranged in parallel with the switching transistors. Depending on the output signals of the operational amplifier OP1, the switching transistors TS1 and TS2 connect the input of the excitation coil 1 to an operating voltage source U. The output of the excitation coil 1 is connected to the operating voltage source U via a diode D2, on the one hand, and to another switching transistor TS3, on the other is in turn connected to the MPP16 microprocessor via an inverter U1 and to the operating voltage source via the resistor R3 and is used for quickly switching the current in the excitation coil on and off. A current measuring resistor RM is connected downstream of this switching transistor TS3. The excitation current determined via the current measuring resistor RM is fed to the inverting input of the operational amplifier OP1 via a voltage divider comprising the resistors R1, R2 and a capacitor C10.

The function of the circuit arrangement shown is as follows. The printer controller DS starts the entire printing system by briefly applying an L signal (signal with a low level) to port P20 of the 8048 microprocessor. The desired printing energy is determined by corresponding control potentials at ports P21 and P22. The simultaneous loading of the ports P21 and P22 with "Low" corresponds to a high impression energy, the loading the port P21 with "Low" and the port P22 with "High", a medium impression energy and the application of the port P21 with "High" and the port P22 with "Low" a low impression energy. The printer controller DS can only become active if a print enable signal (high level) is present at the printer controller (reference symbol H). This signal at input H is suppressed at the beginning of the printing process and is fed back to input H after the correct printing. The signal of the printer control is supplied from the microprocessor fort P16 via an inverter Ü2. The test input TO of the microprocessor 8048 is acted upon by the output signals of the light barrier LS, the continuous light beam "bright" corresponding to the high level.

The digital analog converter DA present at a reference voltage UR is de-energized in the idle state of the submersible magnet system, since all switches SCH of the digital-analog converter present at the outputs port P 10 to port P14 of the microprocessor are disconnected from the reference voltage source UR. This means that 0 volts is present at the non-inverting input of the operational amplifier OP1. While a voltage of +50 mm volt caused by the voltage divider consisting of the resistors R1, R2 and Rm is present at the inverting input, since the resistor R2 is connected to the reference voltage source UR. The output of the operational amplifier OP1 is therefore at a low reference level (low), as a result of which the switching transistor TS2 is blocked via the switching transistor TS1, and therefore no current flows through the excitation coil 1.

In order to excite the excitation coil 1 and thus to actuate the armature, the bit pattern corresponding to the desired current is applied to the digital-to-analog converter DA the ports P10 to P14 and at the same time the switching transistor TS3 is switched on via the PortPl5 with a downstream inverter U1. The operational amplifier OP1 goes to a "high" level at its output and thus controls the transistor TS2 via the switching transistor TS1 and the resistors R. The excitation coil is thus applied to the operating voltage source U and thus current flows through the excitation coil 1. As soon as the voltage drop across the current measuring resistor RM exceeds the output voltage of the digital-to-analog converter, the output of the operational amplifier OP goes back to the low level and thus blocks the transistor TS2 via the transistor TS. However, the current through the excitation coil 1 continues to flow via the freewheeling diode D1. When the current has decayed to such an extent that the voltage drop across the resistor RM is less than the voltage at the output UA of the digital-to-analog converter, the output of the operational amplifier OP1 goes back to the "high" level and the process begins anew, whereby the Current in the excitation coil is regulated in the manner of a switching regulator. The switching frequency of the switching regulator is essentially determined by the inductance of the excitation coil 1 and the feedback capacitor C2, while the switch-on time depends on the output voltage of the digital-to-analog converter UA and thus on the set current.

As already described in connection with FIGS. 3 and 4, the current in the excitation coil 1 is switched off in two ways. On the one hand when the armature path section X2 and the throughput time TX2 pass through, after a time TA then determined directly without the excitation current in the excitation coil 1 decaying. On the other hand, when the armature returning from the impression point is braked by switching off the excitation current VB after an e-function. For quick switching off of the excitation current in the excitation coil 1, the current controller is blocked via the transistors TS1 and TS2 and the shutdown transistor TS3 at the same time. If, on the other hand, only the current controller is switched off via the switching transistors TS1 and TS2 when the switching transistor TS3 is open, the excitation current slowly decays after an e-function, since the diode D1 acts as a freewheeling diode.

The control of the excitation current in the excitation coil 1 is determined by the chronological sequence of the output signals, the light barrier LS. Short-term disturbances, e.g. by scattering adjacent lines or other influences that make the proper control of the microprocessor MP impossible. In order to largely rule out such disturbances, the light barrier is queried twice for each measurement via the microprocessor MP and the input TO, whereby disturbances can be largely eliminated.

Claims (7)

1. submersible armature pressure system with an excitation coil, an anchor designed as a pressure hammer of a pressure hammer device and resting at a stop in the rest position and an optoelectronic sensor arranged in the range of motion of the anchor with an armature control device that detects the output signals of the optoelectronic sensor and the control signals for the excitation coil the excitation coil is actuated by a throughput time of an armature path section detected by the optoelectronic sensor by comparison with a set throughput time stored in the memory, characterized in that a first sequence (TX2, TX3B, TX2B) of the possible throughput times of the armature path sections (X1- X3) and thus the armature speeds corresponding to actual values is stored in binary form, that these first sequences of actual values are assigned a second sequence of binary correction values (TA, ICB, IVB, TAB) in the memory, these binary correction values The course of the excitation current corresponds to that which is necessary in order to arrive at the predetermined target value based on the actual value of the armature speed and that an excitation current control arrangement (OP1, TS1, TS2) is provided which is designed in such a way that when a correction value is supplied converts this correction value into a corresponding analog value of the excitation current. 2. submersible pressure system according to claim 1, characterized in that when the armature (2) is braked, the excitation current control arrangement (OP1, TS1, TS2) is first of all determined with a first correction value (ICB) corresponding to a first braking distance and determined via a first armature distance (X3). is charged that the Excitation current control arrangement (OP1, TS1, TS2) is subjected to a correction value (IVB) determined via a second subsequent armature path (X2) and corresponding to a second braking current, whereby a further correction value (TAB) is assigned to this second correction value (IVB), which is the duration and determines the course of the braking current corresponding to the second correction value (IVB). 3. submersible pressure system according to one of claims 1 or 2, characterized in that the excitation current for braking the armature decays exponentially. 4. submersible pressure system according to one of claims 1 to 3, characterized in that several, with the anchor positively connected by light / dark (K2; K4) or dark / light (K3, K5, K1) limited transitions. Scanning areas (9/1, 9/2) are provided and that when determining the throughput time of the anchor path sections (X1-X3) 'via the scanning device, preferably a subsequent scanning with at least two similar (light / dark (K2), light / dark (K4) ; dark / light (K3), dark / light (K5)) transitions. 5. submersible pressure system according to one of claims 1 to 4, characterized in that a slot ruler (8) connected to the armature (2) is provided with openings arranged thereon as scanning surfaces (9/1, 9/2). 6. submersible pressure system according to one of claims 1 to 5, characterized in that the armature control device an the output signals of the optoelectronic sensor (LS) and the control signals for determining the impression energy (P20, P21, P22) detecting microprocessor arrangement (MP) and that the excitation current control arrangement linked to this microprocessor arrangement (MP) contains a digital / analog converter (DA) with a downstream, which regulates the current in the excitation coil as a function of the output signals of this microprocessor arrangement (MP), as a switching regulator trained current controller (OP1, TS1, TS2, TS3). 7. plunger armature pressure system according to claim 6, characterized by a first the input of the excitation coil in dependence on the output signal of the differential amplifier (OP1) to a voltage source (V) present semiconductor switching arrangement (TS1, TS2) with a freewheeling diode (D1) arranged in parallel thereto, one second, the output of the excitation coil with a current measuring resistor (RM) as a function of a second semiconductor switching unit (TS3) linking the course of the excitation current when switching off, which links the switching signal (P15), the non-inverting input of the differential amplifier (OP1) having the output of the digital / analog -Converters and the non-inverting input of the differential amplifier (OP1) are linked to the current measuring resistor (RM) via a voltage divider (R1, R2, C1).

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