DE2263283A1 - METHOD OF CONTROLLING THE MOVEMENT OF A PRINT CARRIAGE IN FAST PRINTERS - Google Patents

Description

Method for controlling the movement of a print carriage in high-speed printers The invention relates to a method for controlling the movement of a print carriage in high-speed printers. Here, the print carriage can print complete types or the head of a dot matrix printer with a column-wise structure of the print characters.

Such high-speed printers serve in particular as output means for EDP systems, whereby the characters to be printed are stored in order with the greatest possible Speed and continuous printing, and being able to be printed Sign in the continuous print carriage run when the relevant pressure is reached must be accessed.

In the previously known printing units of the type explained above one usually uses a drive motor that rotates continuously in one direction which is coupled to the print carriage via a multi-stage gearbox and magnetic couplings is. For every printing speed, for tabulation and carriage return needs you then have at least one pair of gears, one electromagnetic clutch and the associated one electronic control. You also need at least one magnetic brake, to brake the car when it reaches the end of the line and bring it to a standstill. A simple structure is therefore not possible, especially since the gearbox with the clutches and braking in relation to the actual printer relatively large and is also complex. The complicated structure is also very susceptible to failure given.

It is also known to use stepper motors to drive such print carriages to use. These drives are mechanically simpler, but the necessary one electronic control is then very complex. In particular, however, occur in the Tabulation difficulties arise because the necessary step frequency is the motors overtaxed because of the iron losses occurring in the engine at high frequencies; this results in a relatively low tabulation speed. The relationship between the torque and the mass moment of inertia of the motor is also important for stepper motors not cheap, so that a large engine is required.

The invention is therefore based on the object of a method for Control of the movement of the print carriage of a high-speed printer to indicate which The print carriage carries the print elements and moves them continuously over the print line the characters to be printed in the corresponding print position from a Memory can be called up, which method a simple structure of the drive and drive control.

According to the invention, the drive motor is turned on until the target speed is reached of the carriage run fully energized and the drive motor is then regulated so that it is at If the target speed is briefly excited, the excitation time is made dependent on the deviation from the target speed.

In order to regulate the drive motor in accordance with the invention, it is useful to derive clock pulses from the carriage movement, the pulse sequence of which is proportional to the Wagenlaufge speed is, so that the distance between the clock pulses with the fixed, die.Soll SPEED characterizing time of a timer, which is from the clock pulses is switched on, is compared and that if they are equal or if the clock pulse spacing is smaller the excitation of the drive motor is switched off, and then the excitation of the drive motor is switched on again with the trailing edge of the timer pulse is when the distance between two clock pulses is greater than the timing element time, and this excitation is maintained until the next following clock pulse occurs.

Instead of regulating the continuous running of the print carriage by means of the timing element, this can also be achieved with a multivibrator by after reaching the target speed and after switching off the excitation of the drive motor an astable multivibrator is triggered with the next clock pulse and the excitation of the drive motor is switched on again when the cycle time of the Multivibrators is shorter than the clock pulse spacing, namely with the leading edge of the next multivibrator cycle to the leading edge of the next clock pulse.

It is known to use the print carriage especially for wide print lines to move with a toothed belt to which the print carriage is attached and the. from the drive motor is driven. ~ With such pressure devices it is advisable to to generate the clock pulse sequence e a proportional to the carriage speed To arrange the coding disk firmly on the reverse axis of the toothed belt and on this Encoding disk to provide a clock track on the circumference, which is scanned with suitable means will.

This coding disk can also be used to identify the printing positions serve by adding a radial binary coding per print position on the circumference is provided. In the case of very wide print lines, it is advantageous to use the print line to be divided into several sections and one turn of the coding disk for one section assign. The individual printing sections can then be determined by counting the number of revolutions will.

The invention is explained below with reference to FIGS. 1-4 for the control of the print carriage on which the print head is attached, for example, explained in more detail. They show: FIG. 1 the print carriage with drive in plan view, FIG. 2 the same arrangement in the direction of arrow A in Fig. 1 Fig. 3 the graphical representation of the time Processes of the printing carriage control by means of a timer Fig. 4 shows the graphic representation the timing of the control of the print carriage using a multivibrator.

In Figs. 1 and 2, all parts are omitted for understanding of the invention are not required.

Thus Fig. 1 shows a plan view of the printing unit 1; the fault lines 2 are intended to indicate that the print lines can be very wide. The print carriage 3 carries the print head 4 and the two rollers 5 with the ribbon 6. The print carriage 3 is moved by means of the toothed belt 7, which is suitably attached to the print carriage 3 is attached.

The toothed belt 7 is driven by the drive motor 8 via the gear drive 9 and the toothed belt wheel 10 are driven. On the axis the one on the left At the end of the printing unit located toothed belt pulley 11, which serves as a deflection, is the encoder disk 12 attached; the design of which can be seen from FIG.

The coding disk 12 contains the clock track 13 and the positions on the circumference of the individual pressure points 14 in binary-coded form.

Since it is assumed in the present example that the characters are printed in the mosaic print, each position of the clock track 13 corresponds to one Column of the printed mosaic.

Instead of the binary coding of the positions of the characters can also a simple counting code can be used. However, the binary coded positioning has compared to a purely counting positioning the advantage that it is much less sensitive against glitches and interference caused by foreign bodies, such as scraps of paper, caused. Occurs during binary positioning due to a fault in a or several tracks show an error, this can be caused by an additional parity track be recognized. However, the next print position is correctly recognized again. at counting positioning does not result in an error occurring due to a malfunction recognized and dragged along with other positions, d. H.

the car is wrong. The toothed belt pulley and also the one connected to it binary coded disk should, however, be at least as large in size. like it corresponds to the width to be printed. This leads to difficulties with wide printers. The inertia is quite large, so that the acceleration and deceleration times get too big. Above all, such a large toothed belt pulley with a washer can be used do not accommodate constructively well.

In the solution described, one revolution of the toothed belt wheel corresponds to only part of the print width. In which part the print carriage is located determined by counting. This counting is easy when one turn of the disk 2n print positions (i.e. the binary numbers 8, 16, 32, 64) correspond to, in this In this case, the transition from all tracks "L" to all tracks "0" and vice versa monitored and counted. The counter is at one end of the carriage path through a Limit switch 16 set to zero.

From there, the counter can now count in a defined manner.

The scanning of the encoder disk 12 can be done photoelectrically, what is indicated by the reference number 15. The scanning can also be done by other means, z. B. be carried out by making electrical contact. Since the coding disc 12 rotates synchronously with the drive motor is obtained by scanning the codes in each case one statement about the position of the print carriage.

The drive motor 8 can be reversed in its direction of rotation; in one printing direction he moves the print carriage from left to right, over the print line, with the imprint of the. Character is made while its direction of rotation is reversed at the end of the line to effect the carriage return or to reverse to print. This results in two operating states for the drive motor 8, namely Acceleration or deceleration in the area of inversion and synchronization, if the Print carriage has reached the target speed.

The control of the carriage run to one of the running speed of the print carriage dependent activation of the drive motor is described below explained with reference to FIGS. 3 and 4 for two possibilities.

The first control option uses a timer.

Fig. 3 shows the three diagrams al b and c. Here is the diagram a shows the states of the timer again, while diagram b shows those of the clock track derived clock pulses and diagram c the switch-on times of the drive motor shows.

The timing element (not shown in FIGS. 1 and 2) has a constant Time represented by pulse 19 in Fig. 3a during which this timer remains in a preferred switch position after being pushed. The one from the coding disk 12 or the clock track 13 derived clock pulses 18 or their spacing are with increasing running speed of the print carriage shorter, as can be seen from Fig. 3b can and how it is easily understandable. The shown in Fig. 3c Switch-on times 17 and 22 of the drive motor 8 depend on the comparison of the clock pulse times or - intervals with the retriggerable time of the timer.

In the acceleration phase 17, i.e. at the beginning of the car front or Carriage return the drive motor 8 is fully energized (excited). 'The setpoint speed is determined by the time between.

two clock pulses 18 derived from the encoder disk 12 with the fixed time 19 of the retriggerable timer is compared.

The timer is in each case from the leading edge 20 of the clock pulse 18 triggered again. Equality of time between timing element and interval of clock pulses, d. H. The target speed of the print carriage prevails when the falling edge 21 of the timer 19 coincides with the leading edge 20 of a clock pulse. With this coincidence or with the clock pulse spacing, the timing element time becomes smaller the excitation of the drive motor 8 is switched off and its control switched over so that that the drive motor is regulated to a constant speed of the print carriage will.

This regulation also results from FIG. 3. With the leading edge 20 of the clock pulse 18 the timer is triggered.

If the timer 19 has expired, the drive motor receives 8 a current pulse 22 until the leading edge 20 of the next clock pulse 18 occurs. The print carriage runs slightly slower than the specified one Timing member time 19 would correspond. If the print carriage becomes faster, i.e. it falls the leading edge 20 of the next clock pulse 18 in a timer 19 so becomes the drive motor 8 is not switched off. If a load occurs during the constant Runs up, the leading edge of the next clock pulse comes later, and the Drive motor 8 is energized correspondingly longer. tf exceeds the load a certain amount, this can be determined by a second timer with a longer time will. If the print carriage slows down, so that the next leading edge in this second timing element falls, the drive motor 8 is fully energized (corresponding to Run-up). This second timing element is not absolutely necessary, but it is guaranteed there is another rapid run-up to the specified speed. In order to one obtains, as clearly shown in FIGS. 3 and 4, current pulses for the excitation of the drive motor 8, the duration of which depends on the interval between the clock pulses and thus on the actual speed depends on the running of the car. This type of regulation is very sensitive, especially and the control time constants are small and, above all, the power loss is very low. The drive motor is never supplied with more power than necessary; also occurs no excess power in the electronic circuit that is converted into heat would, since only switching operation takes place.

The deceleration of the drive motor 8 and thus of the printing carriage 3 a slower speed, to standstill or to run in the opposite direction Direction takes place through counter-excitation of the drive motor 8. The The drive motor is energized until the same condition as in the acceleration phase is fulfilled, and the correct direction of travel is checked. The braking on Standstill is achieved by braking to a very slow speed - great Comparison time of the timer - and when the standstill position is reached brief counter-excitation of the drive motor, an additional possibility is through a Magnetic brake given to come to a standstill and hold this position, The running behavior of the drive motor with the above regulation can be with a Compare asynchronous motor.

Instead of the timing element, you can also use a multivibrator, to determine the speed of the carriage. This is based on FIG. 4 explained. In order to start up the drive motor 8, it is activated, as with reference to FIG. 3 explained, excited; The zenith of the rising edge of the first clock pulse becomes a stopable multivibrator is triggered. As long as the distance between two clock pulses is greater than cycle 24 of the multivibrator, the drive motor remains energized. If the interval between the clock pulses is equal to or less than cycle time 24 of the multivibrator, i.e., when the target speed of carriage travel is reached, the excitation becomes of the drive motor 8 switched off. With the next following clock pulse, the astable Multivibrator restarted so that synchronism between the clock pulses (carriage run and the astable multivibrator is made.

If the clock pulse sequence changes in the sense of a longer clock time, i.e. decrease the speed of the carriage run, then proceed to the next rising edge 25 of the multivibrator, the drive motor is re-energized until to the front flank 20 of the next clock pulse 18. The print carriage runs synchronously with the multivibrator at a continuous speed.

The method according to the invention can also be used advantageously, if the characters to be printed are not retrieved from a memory but from Should be entered manually or generally in an arrhythmic manner.

Here, the drive motor is accelerated in the manner described above and stopped after finished character printing, because mosaic print heads or the like, conditional by storing the printing pins, have a certain width and a ribbon the view of the last printed character is also blocked, it is necessary to Bringing the mosaic print head and ribbon out of sight. At acquaintances Solutions this is done by lowering both parts or by moving both Parts of the writing away to the back. Both require a considerable amount of effort and are additional sources of error, especially when you consider the high speed and frequency of recovery are taken into account.

With the new set-up, the print carriage travels again if there is no one Hand input continues by a certain amount in the printing direction to the last character to release to view, and then stops. The stopping takes place through the Drive motor 8, which is braked by counter-excitation in a creep speed and when the standstill position is reached by briefly repeated counter-excitation to standstill is brought. The view of the last pressure point is now unobstructed; a pointer indicates the next pressure point.

If a new character is entered, the carriage moves backwards, prints out the character and moves back to the next position, which is the view of the Character releases.

The printing carriage is controlled by the positioning described. If a character is printed out with manual entry, then in a position memory, which can be part of the positioning, the last printing point is saved. to the memory content is now a certain amount (by how many pressure points the print carriage to continue driving to clear the view), z. B. 4 or 8 pressure points. The print carriage now moves to this calculated position, if they are equal exists between the position memory and the position of the print carriage Manual entry, the same amount is subtracted again in the position memory, see above that the print carriage goes back to the last print point. Now returns the motor reverses its direction of rotation and prints when it reaches the next printing point the entered character and increases the position memory content by the additional printed positions.

The process now begins again as described above Addition of the amount by which the print carriage should continue to move for visual release.

If empty steps are entered, the process can be carried out in the same way -Type run as previously described with the difference that it is not printed. However, the process can be simplified by changing the position memory contents is increased one point and the print carriage moves on one point without the oscillating Perform movement as when printing.

The process of printing with manual entry, as described, can be faster can be executed as a keyboard entry, so no difference to the operator for writing on a normal typewriter. The blank steps of the print carriage are indicated by a pointer 26.

The manual input described above is not based on a procedure Claim 1 is limited, but can be used quite generally for printing unit control will.

9 claims 2 sheets drawing, 4 Fig.

Claims (9)

Claims 1. Method for controlling the movement of a print carriage; of the print types or carries the mosaic print head, for printing along a relatively wide print line, in particular for the continuous printing of characters that can be called up from a memory, characterized in that the drive motor until the target speed is reached of the carriage running is fully excited and then the engine running on regulated operation is switched by briefly when the target speed is not reached is excited, the excitation time of the deviation from the target speed is made dependent. 2. The method according to claim 1, characterized in that for regulation of the drive motor are derived from the carriage movement clock pulses, their pulse sequence that the distance between the clock pulses is proportional to the carriage speed the fixed, the target speed characterizing time of a timer that is compared in each case by the leading edge of the clock pulse is switched on and that if the clock pulse spacing is equal or smaller, the excitation of the drive motor is switched off that then the excitation of the drive motor with the trailing edge of the timer pulse is switched on again when the distance between two clock pulses is greater than the timer time, and this excitation is maintained as long as until the leading edge of the next following clock pulse occurs. 3. The method according to claim 1, characterized in that for regulation of the drive motor are derived from the carriage movement clock pulses, their pulse sequence that the distance between the clock pulses is proportional to the carriage speed the cycle time of an astable multivibrator compared and if the same, the Excitation of the drive motor is switched off. 4. Device for performing the method according to claim 1 and 2, in which the print carriage is attached to a toothed belt that is driven by the drive motor by reversing the direction of rotation of the motor in both directions the print line is movable, characterized in that for generating the carriage speed proportional clock pulse sequence a coding disk (12) fixed on a reversing axis of the toothed belt (7) is arranged and this coding disk has a clock track on the circumference (13) which is scanned by suitable means (15). 5. The method according to claim 1, characterized in that for regulation of the drive motor are derived from the carriage movement clock pulses, their pulse sequence is proportional to the carriage speed, furthermore that the interval between the clock pulses with the fixed cycle time, which characterizes the setpoint speed, of an astable Multivibrator is switched on by the leading edge of the clock pulse, is compared and that if they are equal, the excitation of the drive motor is switched off becomes that then with the the next clock pulse a more stable one Multivibrator is triggered and the excitation of the drive motor is switched on again with the leading edge of the next multivibrator cycle up to the leading edge of the next clock pulse. 6. V experience according to claim 4, characterized in that the coding disk (12) has radially running binary codes on the circumference, which the individual Mark print positions. 7. The method according to claim 5, characterized in that a complete Movement of the print carriage (3) from one edge to the other of the print area Number of revolutions of the coding disk and the resulting Sections of the pressure area can be determined by counting by each at Transition of coding 0 in all tracks to L and vice versa in all tracks of the Coding disk a counter is incremented. 8. Method for the arrhythmic printing of characters, e.g. B. by manual input, the drive motor in particular after a one or more of the preceding claims is controlled, characterized in that that the drive motor is stopped after completed character printing in such a way that If no new entry is made, the print carriage continues to run until it was last printed characters becomes free to view, and that when a character is entered again the carriage returns to the printing position. 9. The method according to claim 8, characterized in that in one Position memory The position of the last printed position is saved and for the memory content one of the number of printing positions by which the carriage continues should, the corresponding number is added and that when a character is entered again this Zabl subtracted in the position memory during the return of the print carriage is that when the so marked pressure point is reached, the direction of the The motor is reversed and the print carriage moves to the next to print out the next character Print point brought and the position memory content around the last printed one Position is increased. Blank page