Electronic arrangement for generating two alternating voltages whose phases are shiftable

An electronic arrangement for generating, from a reference value proportional to the rate of movement, for example, from an a.c. voltage generated by a means of a tachometer generator, two a.c. voltages which can be shifted in phase with respect to each other by a constant frequency-independent amount. An arrangement is provided in which a variable input a.c. voltage is changed to a triangular voltage of constant amplitude and proportional in frequency to the a.c. voltage. There is a first square-wave voltage derived from the triangular voltage and the triangular voltage is inverted. The inverted and uninverted triangular voltage are each applied to one input of two comparators and a manually variable d.c. voltage is applied to the second input of each comparator. The d.c. voltage is manually variable between the maximum and minimum amplitudes of the triangular voltage. The outputs of the two comparators are connected to a bistable multivibrator which generates a second square-wave voltage shiftable in phase by the angle .psi. with respect to the first square-wave voltage by varying the d.c. voltage.

BACKGROUND OF THE INVENTION 
Devices are needed for generating alternating voltages whose phases are 
shiftable relative to each other. 
Alternating voltages which are continuously shiftable in phase by a 
constant angle independently of their frequency are needed to control 
machining operations on workpieces. If, for example, a workpiece is moved 
at a variable speed past several machining tools arranged in tandem in the 
direction of movement and the machining tools are to perform an operation 
at at least two points of the workpiece spaced a fixed distance 
independently of the rate of movement, means to control the tools are 
required. This can be achieved by controlling the tools by means of a.c. 
voltages shiftable in phase with respect to each other by a constant, 
frequency-independent angle. 
SUMMARY OF THE INVENTION 
It is the object of this invention to provide an electronic arrangement 
which generates from a reference value proportional to the rate of 
movement, for example, from an a.c. voltage generated by means of a 
tachometer generator, two a.c. voltages which can be shifted in phase with 
respect to each other by a constant, frequency-independent amount. 
A first square-wave is derived from the triangular voltage, which is in 
turn derived from the a.c. voltage reference. The triangular voltage is 
inverted. The inverted and uninverted triangular voltages are each applied 
to one input of two comparators, each of whose second inputs is supplied 
with a d.c. voltage which is manually variable between the maximum and 
minimum amplitudes of the voltages. The outputs of the two comparators are 
connected to a bistable multivibrator shiftable in phase by an angle .psi. 
with respect to the first square-wave voltage by varying the d.c. voltage.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 is a block diagram showing the basic structure of the electronic 
arrangement for generating two output a.c. voltages variable in frequency 
and of constant amplitude which are continuously shiftable in phase with 
respect to each other by a constant, frequency-independent angle 0 &lt; .psi. 
&lt; 180.degree.. The most important input and output voltages produced by 
the device illustrated in FIG. 1 are plotted in FIG. 2. 
In FIG. 1 the reference value for the output a.c. voltage is the output 
voltage of a tachometer generator 1, which provides a more or less 
sinusoidal a.c. voltage variable in frequency which is driven by a moving 
workpiece or workpiece carrier such as a conveyor belt. For the purposes 
of this description it is assumed that the tachometer voltage has the 
shape illustrated in FIG. 2a and that its frequency is proportional to the 
rate of movement of the workpiece. The input a.c. voltage is first 
converted in block number 2 to a d.c. voltage proportional to the 
frequency of the input a.c. voltage. In block 3, the d.c. voltage is 
changed to a triangular voltage of constant amplitude and proportional to 
the frequency of the a.c. voltage, as described in detail below. The 
waveform of the triangular voltage is illustrated in FIG. 2b and it has an 
amplitude which is constantly U.sub.max or U.sub.min. The triangular 
voltage is converted in the same circuit to a constant amplitude 
square-wave voltage of the same frequency which is shifted in phase by 
90.degree. by a circuit illustrated in block 4. This is the reference 
output a.c. voltage, in the present case a square-wave voltage with the 
phase position 0 whose waveform is illustrated in FIG. 2f. 
The triangular voltage is inverted by the device illustrated in block 5. 
The uninverted triangular voltage is connected to one input of a first 
comparator 10. The inverted triangular voltage is applied to one input of 
a second comparator 12. The other inputs of comparators 10 and 12 are fed 
with a d.c. voltage generated in block 6 which is manually variable in 
amplitude between U.sub.max and U.sub.min of the triangular voltage. The 
effect of this is illustrated in FIGS. 2b and 2d. FIG. 2c shows the 
waveform of the inverted triangular voltage. Also shown in FIGS. 2d and 2c 
is a positive d.c. voltage which is generated in block 6 and corresponds 
to about 0.5 U.sub.max. 
As shown in FIG. 2d, with such voltages at the inputs of comparators 10 and 
12, the comparator 10 provides squarewave pulses shown by the solid lines 
while the comparator 12 provides the dashed square-wave pulse, in which 
case two pulse trains are applied to the bistable multivibrator 
represented by block 7, which provides a square-wave voltage as seen in 
FIG. 2e. This voltage has the same frequency as that illustrated in FIG. 
2f but is shifted in phase with respect to that of FIG. 2f by the angle 
.psi.. The amount of the phase shift is determined by the magnitude of the 
d.c. voltage applied to comparators 10 and 12. 
FIGS. 3, 4 and 5 show how the above-described electronic arrangement is 
utilized in an apparatus for producing ring marks on insulated electrical 
conductors or on any other strand-shaped workpiece. FIG. 3 shows an 
insulated electrical conductor 18 which is advancing at a constant speed 
in the direction of the arrow 19 and on which ring marks are to be made 
with a spacing a. This is done by positioning, on either side of the 
longitudinally advancing conductor 18, a spraying nozzle 20, 21 whose 
color jet 24, 25 is set into approximately sinusoidal oscillation in a 
deflection system 22, 23. At each crossing of the oscillating color jet, 
each color jet 24, 25 produces a color half ring on the conductor 18. This 
principle is known in the art and is described in German printed 
application No. 1,920,966. 
To form a single ring from the two half rings, it is necessary to control 
the second color jet so that it has a zero crossing whenever the first 
color half ring moves past the second color jet or in other words a phase 
shift at a predetermined angle .psi. has to be produced between the two 
oscillating color jets. 
The necessity of the phase shift between the oscillating color jets 
produced by heads 31 and 32 will now be illustrated in connection with 
FIG. 4. For simplicity, a unit consisting of a spraying nozzle and a 
deflection system will hereinafter be referred to as a head so that the 
embodiment illustrated in FIGS. 3 and 4, in an apparatus for producing 
single rings, the head 31 comprises the spraying nozzle 20 and the 
deflection system 22 and the head 32 comprises the spray nozzle 21 and the 
deflection system 23. In FIGS. 4a and 4b the two oscillating color jets 
24, 25 produced by heads 31 and 32 are shown at time t. At this time the 
oscillating color jet 24 of the head 31 produces a colored half ring (FIG. 
4a, zero crossing of the oscillation, point A). At the same time t, 
however, color particles which are to produce the second color half ring 
at the same time t.sub.1 by means of the oscillating color jet 25 produced 
by the head 32, are produced at the point B (4b). Hence the oscillating 
color jet of head 2 must be shifted in phase with respect to the 
oscillating color jet of head 1 by the angle .psi..sub.12. 
In the known marking apparatus as described in German printed application 
1,902,966, this is obtained as follows: one of the heads for example head 
31 was fixed, while the other head, for example head 32 was shiftable 
parallel or perpendicular to the conductor 18, and the phase angle was 
adjusted by shifting this head. The correct phase position or the 
congruence of the two colored half rings can be checked by means of a 
strobiscopic lamp controlled by the oscillation frequency of the second 
color jet. This known mechanical synchronization of the two oscillating 
color jets necessitates a considerable amount of precision components 
which also make such an apparatus unnecessarily susceptible to trouble. 
The amount of mechanical apparatus required for synchronization will 
become apparent from the consideration of the device illustrated in FIG. 5 
which shows the principle of the production of double rings on a conductor 
8. One ring of the double ring, as in the case of the single ring, is 
produced by oscillating color jets of the heads 31 and 32 with the phase 
angle .psi..sub.12 between the two color jets having to be adjusted. The 
first half ring of the second ring of a double ring is produced by the 
oscillating color jet of the head 33; the phase of this color jet must 
differ from that of the color jet of the head 31 between angle 
.psi..sub.13. The second half ring of the second ring of a double ring is 
produced by the oscillating color jet of the head 34; this color jet must 
differ in phase from that of the head 32 by the angle .psi..sub.34, which, 
in the present case, is equal to .psi..sub.12. All three phase angles must 
be adjustable however. This shows that in connection with the known 
apparatus the mechanical synchronization required a large amount of 
mechanical components and considerable manual operation. 
This complexity is substantially reduced by the use of the electronic 
arrangement in accordance with the invention. In the apparatus of this 
invention for producing ring marks, all heads 31, 32, 33, 34 are fixed, 
and the phase differences between the oscillating color jets are produced 
by one or more electronic arrangements of the kind illustrated in 
connection with FIG. 1. The adjustment need no longer be performed on the 
spot, but can also be effected by remote operation or remote supervision. 
For the production of single rings, this is indicated in FIG. 3 by the two 
blocks "Reference Voltage" and "Synchronization". The tachometer generator 
TG corresponds to the tachometer generator of FIG. 1. The block "reference 
voltage" contains the blocks 2, 3 and 4 of FIG. 1. The deflecting voltage 
for the head 31 is generated from the square-wave voltage produced by the 
block 4 and having the reference phase position .psi. = 0. The block 
"Synchronization" of FIG. 3 contains the blocks 6 and 7 and the 
comparators 1 and 2 of FIG. 1. By varying the d.c. voltage of the block 6, 
for example, by means of a potentiometer, the desired phase position 
.psi..sub.12 of the square-wave voltage generated in block 7 is adjusted. 
On this square-wave voltage the deflecting voltage for the head 32, is 
generated. 
The generation of the deflecting voltage from the square-wave voltages is 
described in U.S. application Ser. No. 691,947, assigned to the same 
assignee as this invention. The same principle of an electronic 
arrangement described in the apparatus of FIG. 3 to generate two 
deflecting voltages shiftable in phase with respect to each other can also 
be used for producing double rings, which, as described in connection with 
FIG. 5, necessitates four deflecting voltages whose phases are to be 
shiftable relative to each other. 
The block diagram for an electronic arrangement for an apparatus which 
produced double ring markings is illustrated in FIG. 6. The upper half of 
the block diagram is identical to the block diagram of FIG. 1. To generate 
the square-wave voltage shiftable in phase between angle .psi..sub.13, 
from which the deflecting voltage for the third head 33 is derived, the 
inverted and the uninverted triangular voltage with the reference phase 
position .psi. = 0 of block 3 is applied to an additional pair of 
comparators, comparators 43 and 44. The other two inputs of the 
comparators 43 and 44 are fed with a d.c. voltage by means of which the 
phase angle .psi..sub.13 is adjusted. The bistable multivibrator 45 
following the comparators 43, 44 generates a square-wave whose phase 
differs from that of the square-wave voltage of the block 4 by the angle 
.psi..sub.13. 
To generate the square-wave voltage with the phase angle .psi..sub.34 from 
which the deflecting voltage for the head 34 is derived, the square-wave 
voltage with the phase angle .psi..sub.13 is taken as the reference 
voltage. From this square-wave a triangular voltage of the same frequency 
and of constant amplitude is first generated (block 54). This triangular 
voltage as well as the triangular voltage inverted in the block 55 are 
applied to another pair of comparators, comparators 65, 66 to whose second 
inputs is applied a d.c. voltage according to the desired phase angle 
.psi..sub.34. The outputs of the comparators 65, 66 are connected to the 
bistable multivibrator block 76 which generates square-wave voltage fixed 
in phase by .psi..sub.34 from which the deflecting voltage for the fourth 
head 34 is derived. In the case of a change in the phase position 
.psi..sub.13, the phase .psi..sub.34 thus is changed by the same amount. 
.psi..sub.34 can be adjusted individually by varying the control d.c. 
voltage for .psi..sub.34. 
FIG. 7 shows a circuit diagram for implementing the function indicated in 
block 2 of FIG. 1. In other words, the a.c. voltage of tachometer 
generator 1 is converted to a d.c. voltage proportional to the frequency 
of the a.c. voltage. Integrated circuit IC 1 acts as a pulse shaper which 
changes the more or less sinusoidal voltage of the tachometer generator 1 
to a square-wave voltage of the same frequency. The square-wave voltage 
appearing at the terminal 6 of IC 1 is differentiated by capacitor C1. The 
resulting needle pulses are applied to the control input (terminal 1) of 
IC 2, a monostable multivibrator which generates square-wave pulses of 
constant amplitude and duration. These square-wave pulses appearing at the 
terminal 6 of IC 2 are summed up by means of P1 and C2 whereby a smoothed 
d.c. voltage is obtained which is proportional to the frequency of the 
tachometer 1 voltage and does not follow fast variations in the tachometer 
frequency which may be caused by slip in the tachometer disc and the 
insulated conductor and by means of mechanical oscillations of the 
conductor because R1, P1 and C2 are suitably proportioned. Through P2 and 
R2 this d.c. voltage is passed to IC 3 in which it is linearly amplified 
and then it is smoothed again by capacitor C3. The frequency-proportional 
d.c. voltage is available at the terminal C. 
FIG. 8 shows a circuit arrangement which changes the frequency proportional 
d.c. voltage to a frequency-proportional square-wave voltage and a 
triangular voltage. The circuit arrangement represents a controlled 
wobbulated triangular-wave generator which generates, simultaneously with 
the triangular voltage, a sqaure-wave voltage whose phase is shifted 
90.degree. relative to the phase of the triangular voltage. The circuit 
arrangement comprises blocks 3, 4 and 5 of FIG. 1. 
Operational amplifier IC 6 is connected as an integrator and IC 7 is a 
comparator. Part of the output voltage of the IC 7 is fed back to input 3 
of IC 7. When the two inputs terminals 2, 3 of IC 7 are at the same 
potential the voltage at the output reverses its sign. The voltage at the 
output 6 thus jumps from one supply voltage (+) to the other (-) whereby a 
square-wave voltage is obtained. This square-wave voltage is inverted in 
the IC 8 for reasons of circuit design. At the terminal D, corresponding 
to the output of the block 4 of FIG. 1, a square-wave voltage of constant 
amplitude is provided which is used as a central control signal with the 
reference phase position .psi. = 0. 
The frequency-proportional d.c. voltage is applied to the input C'. It is 
made bipolar and amplified in the operational amplifiers IC 4 and IC 5 
used as d.c. voltage amplifiers and then fed to an electronic switch 
consisting of D1, D2, T1 and T2 and gated by the square-wave voltage at D. 
At the common emitter resistor R3 of T1 and T2 square-wave pulses are 
equal in frequency to the square-wave voltage at D but whose amplitude 
varies with frequency, i.e. if the d.c. voltage C' corresponds to a low 
frequency: small-amplitude, elongated square-wave pulses will be obtained. 
In the case of a high frequency equal-area, high amplitude, short 
square-wave pulses will be obtained. 
These frequency proportional sqaure-wave pulses are applied to the input 2 
of the IC 6 where they are integrated. IC 6 provides at its output a 
triangular voltage which is equal in frequency to the square-wave voltage 
at D and can be taken from the output G in uninverted form and from the 
output H in inverted form (from IC 9). The amplitudes of the two 
triangular voltages are constant, in other words, they are not 
frequency-dependent. 
The circuit arrangement at the upper left of FIG. 9 corresponds to 
comparators 1 and 2 and to the blocks 6 and 7 of FIG. 1 and represents the 
phase stabilizer proper. The two operational amplifiers IC 10 and IC 11 
are connected as comparators 10 and 12 of FIG. 1. The uninverted 
triangular voltage from the output G of FIG. 8 is applied to the input G', 
and the inverted triangular voltage from the output H of FIG. 8 is applied 
to the input H'. The input E is fed with a d.c. voltage corresponding to 
the desired phase shift. This d.c. voltage is derived from a power supply 
unit, (not shown) and adjusted by means of a voltage divider 
(potentiometer). The output voltages of IC 10 and IC 11 are differentiated 
by capacitors C4 and C5, respectively. Of the needle pulses obtained, only 
the positive ones are applied to the inputs of IC 12, a bistable 
multivibrator. At its output I, the IC 12 provides a square-wave voltage 
which, according to the d.c. voltage entered at E, is shifted in phase by 
a given angle with respect to the square-wave voltage at D (FIG. 8 and 
FIGS. 2e and 2f). The lower part of FIG. 9 shows a circuit arrangement 
which processes the out of phase sqaure-wave voltage and the in-phase 
square-wave voltage in order to obtain the deflecting voltages for the 
heads 21 and 22 of the marking apparatus. The out of phase square-wave 
voltage is applied to the input I' and the in-phase square-wave voltage to 
the input D'. IC 13 and IC 14 are used as pulse shapers; IC 15 and IC 16 
are low-pass filters which filter the fundamental sine waves out of the 
square-wave voltages, and IC 17 and IC 18 generate sinusoidal a.c. 
voltages. The connection of IC 17 and IC 18 is described fully in my prior 
application U.S. Ser. No. 691,947. 
FIG. 10 shows the circuit arrangement of the block diagram of FIG. 6 for 
generating square-wave voltages shifted in phase by the angles 
.psi..sub.13 and .psi..sub.34. The triangular voltage applied to the 
inputs G' and H' of IC 19 and IC 20 is again the same as FIG. 9; only the 
d.c. voltage at the input E' is different for the desired phase angle 
.psi..sub.13. The circuit arrangement comprising IC 19, IC 20 and IC 21 
operates in the same way as the circuit comprising IC 10, IC 11 and IC 12 
of FIG. 9. 
At the output I', therefore, a square-wave voltage is present whose phase 
differs from that of the square-wave voltage of D (FIG. 8) by the angle 
.psi..sub.13. The circuit arrangement comprising IC 22, IC 23, the 
electronic switch as well as IC 24, IC 25 operates similarly to the 
corresponding circuit of FIG. 8 (IC 4, IC 5, electronic switch IC 6, IC 
9). The input C' is fed with the same frequency-proportional d.c. voltage 
as the input C' of FIG. 8. 
As a result of the control of IC 21 which in turn is tied to the reference 
generator (circuit illustrated in FIG. 8), the integrator IC 24 in FIG. 10 
is frequency-locked. A change in the frequency proportional d.c. voltage 
at C' does not result in a change of the frequency at the output K (as in 
the case of the circuit illustrated in FIG. 8) but in a change of the 
amplitude of the triangular voltage. Since, however, the amplitude of the 
d.c. voltage at C' is inversely proportional to the period of pulses at 
the electronic switch, rectangles of constant area are applied to the 
input of the integrator IC 24; thus, an out of phase triangular voltage of 
constant amplitude appears at the output K. This triangular voltage and 
the triangular voltage inverted in the IC 25 are used in a circuit 
analogous to FIG. 9 to derive a square-wave voltage shifted in phase by 
the angle .psi..sub.34. 
While the device of this invention has been illustrated and described in 
connection with a device for applying marks to a moving conductor, it will 
be appreciated that is as other applications and that various 
modifications may be made which do not depart from the scope of the 
appended claims.