SU321342A1 - - Google Patents

Description

There is a known method of controlling stepper drives of copying machines, in which signals from a photodeflection device are decomposed into coordinate components and fed to the windings of motor drives of the drive, moving the instrument relative to the product and the photodeflection device relative to the copier.

The proposed method differs from that in that;

a) the number of steps along each coordinate for the period between two measurements of signals determining the average frequencies of steps is obtained by proportional conversion of instantaneous values of the reference voltages simulating the magnitude and signs of the velocities of the reference time intervals in the measurement period, the flow of which at the inputs of stepper drives pulses;

b) the conversion of the instantaneous values of the modeling reference voltages into the duration of the pulses of the time intervals is performed more often than once during the period of the driving voltage;

c) the proportionality factor of converting the instantaneous values of the reference voltages to the duration of the reference time intervals is set on the basis of the total

switching on the master oscillator during the phase shift of the signal voltage relative to the reference voltage, is less than a quarter of the period, after which the frequency of the master oscillator is controlled according to the same law, and the control voltage is obtained by isolating the envelope by the instantaneous values of the reference voltage at the instants the edges of the pulses of the generated voltage signal;

d) the minimum value of the frequency of the master oscillators is set to be greater than the frequency of pickup of the drives, and it is obtained from the frequency of the generator by dividing the numbers of pulses.

The essence of the proposal for the case of a uniform copying speed of a flat curve is explained in the drawings.

FIG. 1 depicts diagrams of the master pitch, supporting and not obtained as a result of the transformation of stresses,

where: and c is the driving voltage with period G;

t / on (+), f / on (), t / on (-X), op (-i) on-line voltages, but which determine the directions and speeds of movement along the coordinates;

(.hX), С / с (-ЬУ), Uc. (-X, t / e (-y) -nan lsi on timed capacitors;

the number of steps of coordinate displacements;

1, tz ... are the times in which the instantaneous values of on-off data are measured.

FIG. Figure 2 shows the idealized trajectory 2 of the copying point's movement relative to the given direction Si, according to the velocity vector V, where the points L and B indicate the positions of the copy point during the measurement, and the point D indicates its position at the maximum error.

FIG. 3 shows similar figures to FIG. 1 voltage plots for measuring the instantaneous voltages into pulse duration twice a time during the measurement period, where, in addition to the symbols m / lane already entered, there is a break time between individual "bursts of pulses"; and f / c, the voltages applied to other chroniruyusha, their capacitors during the repeated (per period) conversion.

FIG. Figure 4 shows the idealized trajectory of the copy point in the two-time conversion, where the points L, B indicate the position of the copy point after the first transformation.

FIG. Figure 5 shows the dependences of the number of steps l over the period between two measurements, the frequency / gene of the generator, its generator, and the reference time intervals / op, determined by the discharge time of the clock capacitors, with combined control.

FIG. 6 shows diagrams of strains similar to those of FIG. 3, for the occasion

 with (+ F1) .- (d + 1) -f, where

i

k - Q, 1, 2, 3, ..., and F1 - the initial phase.

FIG. 7 shows curves illustrating a method for obtaining a control voltage for adjusting the frequency of the master oscillator, where f / ynp is the control voltage, and t / on is the reference voltage, which during the period simulates the required dependence of the control voltage on the phase angle .

FIG. 8 one of the possible schemes of the controlled oscillator is given, and in FIG. 9 is a functional diagram of a system implementing the proposed method, which is named for controlling the portal gas cutting machine. The voltage at the output of the photo-reading device, which is moved along the coordinates of the drawing synchronously with the movement of the cutters, is used as the setting voltage. Here / is the copied contour, 2 is the objective lens, 5 is a sweep diaphragm, 4 is a photosensor, 5 is an electric motor, 6 is a signal conditioner, 7 is a source of reference voltages, 8 are instantaneous voltage converters in pulse duration, 9-14 - logical cells "OR 15, 16 - logical cells" MEMORY, 17, 18 - coordinate master oscillators, 19, 20 - keys, 21, 22 - distributors, 23, 24 - control voltage converters, 25, 26 - stepping

readers of coordinate readers of a reading device, 27, 28 - gear reducers, 29, 30 - master cutters of coordinate drives of cutters, 31, 32 - torque amplifiers.

FIG. 10 illustrates the selection of the minimum frequency of the master oscillators.

FIG. Figure 11 shows a circuit for converting instantaneous voltage to pulse duration.

The new method is illustrated by the example of copying with a constant velocity flat curve, the slope of which at the copy point relative to the reference coordinates is characterized by the phase of the voltage obtained by rotating the edge of the contour being copied.

Since, when copying a flat curve with a constant speed (a case typical of gas cutting), the speed of movement of the actuator along two mutually perpendicular coordinates are respectively equal to:

V I / O sin a,

y st cos

where Ko is the speed of movement along the contour, and is the angle of inclination of the tangent at the copying point to the X axis, then the coordinate speeds of movement can be simulated by sine-wave (sine-cosine) stresses;

,: UZTSr,

Woo-woo; W (, so8 f,

where / 7o is the voltage amplitude, f is the phase of the reference voltage (axis X) at the time of measurement, determined by the phase of the synchronous signal voltage. The proposed method of controlling the stepper coordinate drives of the master and actuator of copying machines by instantly determining the number of jaws of coordinate movements for the period between two measurements of the signal voltage phase is as follows.

From the reference sine-cosine voltage, synchronous to the sweep voltage, four series of single-pole pulses are created by half-wave straightening (curves

t / on (+), Uo (+ Y), U, (- X), Uon (-Y) in FIG. 1), simulating the movement speeds in mutually opposite directions of both coordinates. The polarity of the reference pulses is not critical. She is

it is determined only by the convenience of the circuit implementation.

To determine the coordinate velocities for each measurement (on the sweep period) at times determined by

By moving the sweep element over the boundary of the contour in front along the copying path (for example, ti, tz, etc.), the instantaneous values are measured: each of the four series. These voltages are immediately pulsed, for example, by quickly charging capacitors to instantaneous g) the first reference voltages with their subsequent linear discharge (curvature curves (m), and (- X). For the thus obtained the reference time intervals to the inputs of the stepping drives from the master oscillator are impulses with a constant tracking frequency. Under their action, the jog drives move the readings to the selected device and the cutters in both coordinates by a certain number of steps. In this direction, however, both coordinates are determined However, the fact of the presence (at the time of measurement) of the voltage of a series of pulses, each of which simulates speed in one direction, is available. The number of steps performed by the drives in both coordinates are in sine-cosine dependence. Therefore, the copy point during the sweep period will move to equal distances. This ensures that the average copying speed is constant. However, the copying point's non-shifting speed during the scanning period is uneven due to the constant working speed (frequency) steps in both coordinates. The motion path of the copy point is also different for the same reason from the ideal path. After measuring the instantaneous values of the modeling voltages, both coordinate nanowires operate with equal speed (except for special cases of moving along one axis only) and therefore the copying point moves along the bisector of one of the square angles of the reference coordinates, and then along one of the axes to the point of intersection with mine, tangent to the contour being copied, the direction of which is determined at the time of the last measurement (Fig. 2). Ptak, the ideal trajectory during the sweep period coincides with the segment AB, BV, etc., and the copying point moves along the sides of an oblique triangle, the obtuse angle of which always remains unchanged and is equal to 135 °. Since the trajectory of movement S2 of the point of convoration is a broken line located on one side of the given trajectory Sl, a copying error occurs, the average value of which is equal to half the height of the AGB triangle. As the angle of inclination of the rectilinear portion of the trajectory S to the coordinate axes changes, the copy error changes in magnitude. When the angle of AGB is constant and the segment of AB is, the error will be maximal if the sides of the AG and GB are equal to the LGB triangle, i.e. when the direction vector of the movement with the bisector of square angles is 22 ° 30. Denote the average value of the maximum error by b and express it through the drive step D /. Since the value of AB does not depend on the direction of movement, it can be expressed through a series of steps n during the sweep period, if the movement is made only along one coordinate and the conversion proportionality factor is chosen so that the full activation of the master oscillator is achieved as follows: In turn, where / is the frequency of the drive steps, F is the frequency of the sweep. Thus .0,1-A /. zom b; To reduce the copying error for this reason, it is suggested that instantaneous values of the reference voltages be converted into pulse durations more than once per sweep period. The basis of this possibility lies in the property of shifted but synchronous phases that are identical in shape and amplitude, which consists in the fact that equal instantaneous voltages of these stresses occur at time intervals determined by the phase shift. Consider this proposal on the example of a two-time conversion period (see Fig. 3). The times tl, tz for re-measurement are determined by sections of voltage pulses Uc. At these times, the instantaneous voltage of the series t / oii (-j--) and i / on (- Y) is equal to the instantaneous voltage of the series op (-A) and Uon. (+ Y) at times ti and 12 respectively. The capacitors of the discharge of capacitors, obtained after the second measurement, are combined by a logical operation of an ILP with the same imiums obtained after the first measurement and, similarly to the previous one, used in the nrn control of coordinate drives. Due to the fact that the total number of pulses arriving at the inputs of stepper drives during the sweep period is divided into two equal parts twice, the copy error also decreases by half (see Fig. 4), since the position of the point the copying during the scanning period coincides twice with the defined direction (points A, A, B, B, etc.). When the pa inputs of the stepping drives of the control emulsions are supplied in separate "packs with some uninterrupted time between them / lane (see Fig. 3), the pickup frequency of the drives decreases. Reducing the frequency limit of the stepper drives while maintaining the same copy speed leads to an increase in step A /, which somewhat reduces the accuracy of the copy. In order to use the full frequency capabilities of stepping drives in the method of inertia-free determination of the number of steps for

reliable pickup of drives is offered upon reaching a certain phase angle. between the reference voltage (for each coordinate) and the voltage of the signal (and after the generator is fully turned on, its frequency should be adjusted sinusoidally). lIpH this maximum generator frequency should correspond to the maximum frequency of the drive. This is shown in Fig. 5 and 6.

Let the initial phase of the pulses of the voltage signal Uc (see Fig. 3) and the reference voltage Uou (+) coincide. Then the number of steps n for the sweep period T in the X coordinate is zero (the motion is carried out only in the Y coordinate).

With the appearance of a phase shift between the voltage of the signal and the reference voltage at hours, the generator tote / gene / tg7g, the number of steps per sweep period is determined by proportional conversion of the instantaneous values of the reference voltage and the duration of the pulses to the drive input, within the angles φ (A; l + / 1) - (+ 1) -tpi, where, 1, 2, ... (see Fig. 5), at which the generator is turned on completely; according to the same law, the frequency of the generator is regulated.

The method of obtaining the control signal (Uupr is explained for this purpose in Fig. 7, if a symmetric multivibrator is used as a master oscillator (see Fig. 8), has a direct proportional dependence of the oscillation period on the charging voltage of the chroning capacitors C, quality

which is t / ynp.

In order to change the frequency of the generator sinusoidally within the limits of its full switching angles, the control voltage must be proportional to the inverse of the frequency function, i.e.

upv - -

control

/ gay

where a is the proportionality coefficient.

The control voltage, which varies within the full turn-on angles of the generator according to the required law, is obtained by extracting the envelope from the instantaneous values of the reference voltage, which simulates the law of f / ynp variation (see Fig. 7). At the same time, time for measuring instantaneous values of the simulating voltage is determined by the phases of the fronts of the formed wiring. signal f / c (see. Fig. 3).

The amplitude of the previous burst of pulsating voltage is remembered in the form of a constant-voltage capacitor charge voltage, which in the new burst is adjusted to the new amplitude value. Since the f / ynp voltage with this method of selecting the envelope remains constant during the sweep period, the tracking pulse frequency does not change during this time either.

To be comparable to the discreteness of the drive, it is necessary that when the copying point is shifted one step from the edge of the contour (D /, see Fig. 10), pulses are fed to the input of the stepper drive. The fulfillment of this condition depends on the ratio of the frequencies of the master oscillator and the sweep.

In the case of movement along one coordinate, the copying point offset by one step (from O to O) corresponds to the phase shift of the foch signal, which, as follows from FIG. 10 equals;

 - arssin--,

where A / is the drive pitch, R is the radius of the orbit of the sweep element.

The correction of the error that has occurred will be possible if, over time /, determined by the sweep period T and the phase angle of the foch

    D) to the input of the stepper drive post 360 /

pit at least one pulse. Hence, the generator frequency / gene can be expressed in terms of the sweep frequency F as follows:

,, J 360 ° - F

/ gene - T -

A I R

arc sin in case of setting the frequency of the driver

generator, as discussed above (see Fig. 5), this value of the frequency corresponds to the minimum frequency of the generator fmi-n. Since the minimum value of the oscillator frequency, determined from the condition

required static copying accuracy, usually much higher than the frequency of pickup of stepper drives, then the latter must be obtained from the frequency of the generator by dividing.

The functional diagram of the stepper drive control system is shown in FIG. 9. The driving voltage is generated by the photosensor 4 under the action of the luminous flux reflected from the replicated circuit 1 and formed by the lens 2, as well as by the diaphragm 5 rotated by a synchronous electric motor 5. The voltage of the photosensor 4 is converted into a series of square pulses (He, see Fig. 1 and 3).

The output voltage of the driver 6 and the reference voltage (see Fig. 3) from the source 7 of the reference voltage are supplied to the input converters 8. Each of these converters converts the instantaneous value

the applied reference voltage at the time of the front or cutoff of the pulses i, tl, tz, tz, and so on, into the duration of the pulses of the reference time intervals.

The speeds of movement in two coordinates (in four directions) are determined by the instantaneous values of the four series of reference pulses Uo-n. (+ X), Uoa (+ y), Uon (-X),

UOH (-Y (CM. Fig. 3). For conversion

the transmitter + X, --Y, -X, -Y, the inputs of which are connected to one of the reference voltages and the voltage of the signal G / s, a positive differential of which appears at the time points / t ty, etc. For re-conversion of equal instantaneous voltage values in the second half of the period also requires four similar converters + X, -L Y, -X, -y, whose inputs, besides the reference voltages, summed the inverted voltage of the signal Uc with positive differences at times t, etc. The presence of pulses at the outputs of converters with one another sign is a sign of the direction of movement. Since these pulses are discrete in time, the direction of movement is remembered by cells "MEMORY 15 and 16, to the inputs of which the pulses from the like converters with the same sign arrive through logical cells" OR 9, 10 and /, 14. The duration of the pulses at the outputs of the same name The transducers, regardless of sign, determine the speed of movement over the coordinate. Therefore, the outputs of all converters of the same name are combined with the cells "OR // and 12.

Coordinate master oscillators 17 and 18 are connected to the inputs of the distributors 21 and 22 via keys 19 and 20 controlled by the output pulses of the converters 5. Therefore, the numbers of pulses supplied to the inputs of the distributors are proportional to the frequencies of the master oscillators and the duty cycle of the keys.

The synchronization of the movement of the cutters and the reading device is ensured by the parallel connection of stepper motors 25, 29 and 26, 30. The required scale of the speeds of movement of the driver and the cutters is determined by the selected gear ratios of the gearboxes 27, 28 and the torque amplifiers 5 and 32.

Let the voltage phase of the signal be such that the front and edge of the pulses Uc coincide with the beginning and end of the SUPPORTING pulse Um ((see. 3). At the same time, at the outputs of all converters related to the X coordinate. The pulses of the reference time intervals are absent, and at the outputs of the converters related to the y coordinate, the length of the pulses is equal to or half the length of the pedeode, and the motion is carried out only along the y coordinate with a speed determined by the maximum frequency fmnv of the generator 18 controlled by the converter 24 (see . 5). Since the front Uc pulses (times / i, /, and so on. D.) Coincides in time with the reference pulses sepia FP7 (4-Y), move to the coordinate Y coincides with its direction po.pozhitelnym.

When lazo pulses shift U ,. for example, to the right, there are PULSES at the outputs of the -X and -X converters, which determine the number of movement points along this coordinate in the -X direction. As the signal continues to phase shift, the generator is turned on completely, and from this point on, the frequency of the generator 17 starts to increase due to the control voltage (Uupr from the converter 23. When the signal phase is opposite, the pulses of the reference time intervals appear at the outputs and + X. The cell "MEMORY 15 is transferred to the" opposite state, as a result of which the switching order is changed by the distributor 21 of the phase windings of the motors 25 -k 29 VI, the movement is made in the opposite direction direction, etc.

FIG. 11 shows one of the possible

circuits of the converter of instantaneous values of voltage to pulse duration. The possibility of implementing the remaining nodes of the system is well known. Consider the principle of operation of the converter.

The input voltage is supplied to the input voltage, and the input voltage is the reference voltage.

During the lifetime of the flat voltage pulse voltage f / c or in the pause, the triode T is opened by the base current flowing through the resistor R. The voltage on the collector of the triode D) is constant and close to zero. Similarly, the triode T is open, supporting the output voltage to close

to zero, regardless of the periodically opening and closing output of the triode Gz of the master oscillator.

At the moment of a positive jump in the voltage pulse Uc, the triode G for some time,

detected by the discharge of capacitor C is closed. During this time, the clock capacitor Cx is charged to the voltage existing on Ix. With the subsequent opening of the triode T

the timing capacitor is discharged through the timing oisistor, locking the triode T. During this time, the output receives pulses with a constant frequency of the master oscillator, as a result of which their number is proportional to the instantaneous value of the reference voltage determined at the time of the pulse of the generated master voltage.

The coefficient of proportionality of the transformation is determined by the time constant of the RyiC timing chain and is determined from the condition that the generator is turned on completely.

Subject invention

55

Claims (3)

1. A method of controlling stepper drives of copying machines, in which signals from a photodeflection device are decomposed into coordinate components and fed to the windings of motor drives of an actuator, moving an instrument relative to the product and a photodiauntee, a device relative to a copier, characterized in that in order to increase the speed of copying machines and the accuracy of the copy, the period between two measurements of the signals, determining the average frequencies of the steps, is obtained by proportional conversion of the instantaneous values of the reference voltages simulating in the measurement period the magnitudes and signs of the velocities for each coordinate in the duration of the pulses of the reference time intervals during which pulses are applied to the inputs of the stepping drives. 2. A method according to claim 1, characterized in that the conversion of the instantaneous values of the modeling reference voltages to the duration of the pulses of the time intervals is performed more often than once per source of the driving voltage. 3. The method according to paragraphs. 1 and 2, characterized in that the proportionality factor of the instantaneous values of the reference voltages in the duration of the reference intervals is set on the basis of full switching on of the master oscillator during the phase shift of the signal voltage relative to the reference voltages, less than a quarter of the period, after which the frequency of the master oscillator, and the control voltage for this purpose is obtained by pulling the selection of the envelope at instantaneous values of the reference voltage at the instants of time at which the fronts appear pulse voltage generated. ig.2 Jrrd. ™ J QD J 0 & g FIG. eleven