DE1272338B - Magnetic tape recording system, particularly for television signals - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

H04n

German class: 21 al -32/11

Number: 1 272 338

File number: P 12 72 338.5-31 (A 32604)

Filing date: August 4, 1959

Opening day: July 11, 1968

The invention relates to a magnetic tape recording system, in particular for television signals, in which, as already proposed, the magnetic tape on a rotary head assembly by a first Electric motor is moved past and the rotary head assembly is driven by a second electric motor will.

It is already known in a magnetic tape system for storing and reproducing color television signals to record a reference frequency which, when played back, corresponds to the rhythm of the fluctuations of the recording device is changed. This is done in conjunction with a second frequency an error signal is generated to compensate for those errors in the modulation components of the color television signal caused by the recording and reproducing device will.

The invention relates to a system of the type mentioned at the outset, in which a generator is used for generating of pulses at a frequency proportional to the speed of the rotary head assembly for feeding the belt drive motor and a source of pulses of a second type at a reference frequency and a comparator for the pulses of both types to form an error signal for control the frequency of an oscillator are provided, the output energy for feeding the second, the Rotary head assembly driving electric motor is used.

The error signal controls the frequency of the feed current of the drive motor of the rotary head arrangement. Such a servo control system ensures that the vertical synchronization pulses of the television picture are recorded at the same point on the magnetic tape for each picture part of the composite television signal. This system is sufficient to control fluctuations in the speed of the rotary head drive motor, provided that the fluctuations are relatively slow, and it then ensures a relatively stable supply current. However, when sudden or large frequency fluctuations occur, very large error signals are generated which cause overcorrection and result in additional fluctuations in the speed of the rotary head drive motor. Such difficulties can arise in particular as a result of load fluctuations on the rotary head drive motor, namely when the individual heads come into and out of contact with the magnetic tape. A similar overcorrection can also result if the incoming syn magnetic tape recording system,
especially for television signals

Applicant:

Ampex Corporation,

Redwood City, Calif. (V. St. A.)

Representative:

Dipl.-Ing. F. Werdermann, patent attorney,

2000 Hamburg 13, Innocentiastr. 30th

Named as inventor:

Harold Victor Clark, Menlo Park, Calif .;

Josef Roizen, Palo Alto, Calif .;

John Franklin Varnell Jr., Menlo Park, Calif.

(V. St. A.)

Claimed priority:

V. St. v. America 8 August 1958 (754 098)

chronisationssignal suddenly fluctuates in its phase, which z. B. can occur if the program source is switched from one station to another.

It is already known to eliminate the effects of unwanted phase fluctuations like them may occur during magnetic recording or playback of television or similar signals, in the case of a reproduction device from the auxiliary signal taken from the magnetic carrier and a frequency-constant comparison signal to form a control signal by phase comparison, the one controllable delay stage controls so that the also removed from the magnetic carrier TV signal or other signal through the delay stage in the sense of reducing the Phase difference is delayed more or less.

According to the invention, the difficulties mentioned are eliminated in that the former, for feeding the belt drive motor pulses for phase synchronization of a second oscillator are used, the output frequency of which corresponds to the nominal speed of the rotary head assembly, and that a comparator for the phase of

809 569/399

3 4

the first-mentioned pulses with the output frequency of a counter-pressure roller 14 acts, moved past. It second oscillator is provided to a second can have multiple head units 16 on the circumference To form error signal, the instantaneous value of a head drum 18 arranged by a Phase changes of the two first-mentioned pulses ent- synchronous motor 19 is driven. A leadership speech and that a device for changing the 5 device 21 is used to buckle the band, wah phase the output frequency of the first oscillator rend it by the head units, corresponding to the second error signal. The guide device 21 can see one out is. tenen part (not shown) have on which

In this way the mentioned servo system suction air is applied to the belt with the Obermit Provided facilities that serve to reliably touch the io surface of the guide to hal-sensitivity for high frequency fluctuations. When the head units decrease their circular orbit, and a second servo system is passed through, they are added in constant pressure, to avoid the high frequency fluctuations touching the tape.

without affecting overcorrection. The tape 11 is fed from an unwinding roller 22 as the need to be corrected High frequency fluctuations passed through rotary 15 and wound onto a take-up roll 23. Fluctuations in the number of the head drive motor caused. The tape is self-adjusting are, the instantaneous value changes of the guide pins 24, 26 and rollers 27 and 28 on the Frequency of the turret speed propor head assembly 12 passed. The winding roll-up Signals to form an error signal can, as usual, be attached to winding disks uses. This error signal is then used to change 20. The winding plates are driven, as usual, the phase of the supply current for the turret motor by electric motors.

and thus to eliminate the speed- The heads are through a commutator 29, which

Fluctuation. in Figs. 1 and 2 is indicated schematically, with

If the supply current of the second, the rotary head is connected to the electronic elements of the system driving electric motor from a 25 den. The commutator can, for example, Schleifmit Sawtooth wave operated multivibrator rings that are connected to one of the heads, so the second error signal can be used to, furthermore, stationary brushes, which the grinding Convey the reference voltage level of the sawtooth shaft to contact with the associated slip rings, change to change the phase of the supply current of the second

Control engine. 30 densities of the head drum 18 and the drive roller

The formation of the second error signal can be kept in a specific relationship by 13. In the Exciting a reproduction provided as a second oscillator becomes the same within narrow limits Resonance oscillator with the impulses of the first kind, relationship maintained. For this purpose, the the frequency of which the rotational speed of the head recording operation a control signal on an arrangement is proportional, take place; the special track is through along one edge of the tape Frequency of the resonance oscillator equal to the nominal a magnetic head arrangement 31 recorded. That frequency of the impulses of the first type. The control signal is reproduced during the playback process.

The phase comparison is made between the inputs and the output, amplified and used to control the relative output pulses of the resonance oscillator, the head drum and drive roller move forward took. 40 used. A recording head 32 is used for recording

The special features of the invention are shown in the drawing of sound information on the other edge of the details even more clearly on the basis of the following description volume. Audio track and control track erasure heads 33, 34 exercise in conjunction with the drawings. can lead the heads 31 and 32 respectively.

F i g. 1 is a schematic representation of a die in the block diagram of FIG. 1 shown

Magnetic tape recording and / or reproducing 45 electronic circuit can be incorporated into a circuit device according to the invention; part for the cruise control and a

F i g. Fig. 2 is a top plan view of dividing a circuit part for signal recording, matching tape transport device; The signal recording and playback switch

FIG. 3 is a block diagram for explaining a device is shown in the lower part of FIG. Control system according to the invention; 50 The circuit can have suitable devices for establishing

F i g. Figure 4 is a detailed circuit diagram showing a modulated carrier in conjunction Part of the control system of Figure 3; with recording amplifiers. Before-

F i g. 5 is a block diagram for explaining an FM (frequency modulation) another embodiment according to the invention; Recording is used, but a

Fig. 6 is a circuit diagram using part of the sound 55 AM (amplitude modulation) recording device of the embodiment according to FIG. 5 shows; will. The recording electronics can consist of one

F i g. 7 and 8 show the signal waveforms on modulator 36, which receives the input signal, and different points of the circuit according to FIG. 1, a recording amplifier 37 exist, the 3 and 5, and picks up the output signal of the modulator. The end-

F i g. 9 shows the signal waveforms at various 60 output signals from the recording amplifier 37 those points of the editing impulses forming the sound is constantly the individual head amplifiers 38, 39, tion. 40 and 41 supplied. When recording is the

To understand it, it appears necessary to set the switch 42 so that the output signal System in its entirety to be explained in detail, each head to the associated head amplifier 46, 47, tern. 65 48 or 49 is fed. The amplifiers are with

Like F i g. 1 and 2 show, the magnetic tape 11 is connected to its outputs to the switch device 51 Longitudinal direction on the magnetic head assembly 12 closed. From this a single-channel signal is generated by means of a drive roller 13, which in connection with (combined signal) a demodulator 52 pulls

directs. The switching device is successively and alternately on the individual outputs of the amplifier 46 to 49 switched when the respective heads have swept across the tape.

It can be seen that there is a need to reproduce the amplified output signal always derived from a head, with one of the preamplifiers 46 to 49 in such a Moment during the signal is switched to the next preamplifier, if the smallest possible Distortion is introduced into the reproduced signal.

It can be used an electronic switching device, the z. B. controlled electron tubes as a single switch for the signals from each of the four preamplifiers. The control impulses for these tubes are derived from a square wave generated by a photocell 53 in conjunction with a light source 54 is generated. The light source is projected onto a disc or wheel 56 which half black and half white. The photocell also generates a rectangular oscillation a frequency that depends on the speed of rotation of the head drum. The output signal is on a pulse shaper 57 is placed, then fed to a filter 58 and then applied to the switching device. The task of the switching device is to generate the pulses from this initial clock signal form, which are necessary for switching the associated tubes at the correct time.

When reproducing television information, it is desirable to have a blanking switch 59 in conjunction to use with the switch to force the switching operation during the horizontal Blanking intervals takes place. The blanking switch receives its information from the working amplifier 61. The signal demodulated by the demodulator 52 is applied to the working amplifier. The amplifier serves to keep the signal for onward transmission by radio or some other type of transmission to make suitable. Its main purpose is to remove any disturbing noise from the blanking and Remove sync pulses (or from the area between them) and any noise during the image interval to be limited to prescribed peak values. In addition, the working amplifier forms a device for correcting the Video linearity and for local or remote control of both video and sync levels.

As already mentioned, the rotational speed of the head drum 18 is synchronized and the same Phase with the incoming reference signal, and preferably also are devices to dampen any pendulum oscillations of the head drum due to disruptive compensation processes caused by electrical or mechanical Causes may arise, provided. A servo system can serve to control the heads in relation to the Set the input reference frequency precisely and synchronize the rotation of the heads with respect to them. As a result, the recorded signal is accurately recorded from track to track. The system contains a slow servo loop for synchronization and adjustment and a fast servo loop, which serves to counteract fluctuations in the head phase position due to mechanical or electrical compensation processes to dampen.

The reference frequency can either be from the video input signal or from a. local grid energy source be derived. According to FIG. 1 is the video signal to a sync separator 71, which serves to separate out the synchronization pulses and to feed them to terminal 72. If the local line frequency is used, the input line is fed to a pulse shaper 73 placed, which is used to form pulses that have the mains frequency and these to terminal 74 to lay. A switch 76 is used to switch the device to either the mains or the Set the video signal.

The selected clock pulses are fed to a multivibrator 77 which forms square waves and feeds this to a phase comparator 78. The phase of the square wave signal from the multivibrator 77 is compared with the phase of the signal from the frequency distributor 79, and a control signal is derived from it. The output signal of the frequency distributor 79 corresponds to the output signal the photocell 53; it is shaped and divided in terms of its frequency so that it has the same frequency has like the multivibrator 77. If the signals applied to the phase comparator with regard to phase and frequency are the same, there is no output and the reactance tube oscillator 80 oscillates at its nominal frequency. But if there is a phase difference, the oscillator will turn on Signal supplied that increases or decreases its working frequency. The output of the oscillator will be on a multivibrator 81 is placed, the output signal of which is fed to a sawtooth wave generator 82. The output signal from the sawtooth wave generator is fed to a mixer 83. That Shaped output signal of the photocell is also applied to a resonance oscillator 84 and is used for Triggering the resonance oscillator so that it starts producing damped sine waves in phase with the to emit impulses applied to it. The output of the resonance oscillator is sent to a phase comparator 86 laid. The signal from the pulse shaper is also sent directly to the phase comparator. Thus, the phase comparator is used to compare the phase of the direct pulse with that of the to compare the previous impulse from the photocell. Any variation in head speeds during this interval generates an error signal on line 87. The error signal becomes on the mixing device 83 is placed. The mixing device 83 is used to raise and lower the level of the sawtooth voltage applied to it. This sawtooth tension is applied to a cutting device 88 placed, which is used to cut out a small predetermined piece of the curve. So if that Error signal raises and lowers the level of the sawtooth voltage, so the phase of the trailing Edge of the cut signal changed. The trailing edge of the cut signal is used to Triggering a multivibrator 89 which generates a square wave, the frequency and phase of which are dependent are of the difference between the output signal from the photocell and the reference frequency and also any changes in head speeds between successively generated electrical impulses. The output of the multivibrator is fed to a filter 91, which is used to generate a sine wave to apply to a

Three-phase amplifier 92 is used, which drives the synchronous motor 19.

To explain the mode of operation, reference can be made to FIG. 7 and 8 are referred to. In Fig. 7, A show the video synchronization pulses that occur at terminal 72 . In Figure 7, B , the square- wave output oscillation of the multivibrator 77 is shown schematically. The input signal from the frequency divider 79 has the same frequency. Fig. 7, C shows the output of the phase comparator which is applied through a filter to remove its DC component. This DC signal is then used to control an oscillator 80 whose output signal is shown in Figure 7 D. The phase of this signal is controlled by the photocell output. The oscillator output is then fed to the multivibrator 81 , which generates an oscillation of the type shown in FIG. 7, E forms, and from there the sawtooth wave generator, which generates a sawtooth voltage according to FIG. 7, F generated.

In Fig. 8 the operation of the mixing device and the cutting device is shown more clearly. In Fig. 8, A is the sawtooth voltage applied to the mixing device compared to the illustration in FIG. 7, F reproduced enlarged. This tension is, as indicated by the arrows 93, moved up and down. The cutting device is, so to speak, a window which only lets through a defined section of the waveform and has a fixed position, as is indicated by the dashed lines 94 and 96. Thus, as the level of the sawtooth voltage moves up and down, the trailing edge of the exit from the cutter shown in FIG. 8, B , in phase as indicated by the arrows 97. Thus, the trailing edge moves to the left when the sawtooth voltage is lowered and to the right when the sawtooth voltage is increased. It should be noted that a phase shift of a full 360 ° can be achieved. In the circuit according to FIG. 1 the trailing edge is then used to trigger a multivibrator, which generates a square wave, as in FIG. 8, E.

The signal applied to the motor 19 thus has four times the frequency of the synchronization waveform on when it comes from the photocell. The complete system is in terms of the reference frequency synchronized and stabilized with respect to the changes in speed of the head drum. the The effect of this system is that a record is made in which the vertical Synchronization pulses a position on the magnetic tape that is predetermined within narrow limits to have.

The output signal from the frequency divider 79 is also applied to a filter 98 which forms an output signal of substantially sinusoidal shape from the square wave applied thereto. During the recording process, the filter 98 is applied to an amplifier 99 and the amplified signal is used to drive the drive roller motor 101 . The drive roller motor is thus operated at a rotational speed which is directly related to the rotational speed of the head drum. In practice, the drive roller is, so to speak, "rigidly" coupled to the head drum. The tape moves a predetermined distance in the longitudinal direction for each complete revolution of the head drum.

The pulse shaper 57 is also applied to the control track amplifier 102 . The output from the amplifier 102 is applied to the recording head 31 to form a recording track along the edge of the tape.

The control frequency is applied again during playback. The frequency can be the network frequency, the frequency of a local oscillator or the frequency of the synchronizing video signal. This signal is applied to the servo system described above and is used to operate the head drum motor at the correct rotational speed. The control track head is connected to a playback amplifier 103 and the amplified signal is applied to the drive roller servo 104 . The drive roller servo includes a phase comparator which compares the reproduced control signal with the signal output from the photocell to form an error signal. The error signal is fed through a filter to the grid of a reactance tube, which is one of the frequency-determining elements of an oscillator. The oscillator is nominally operating at the correct frequency, with the frequency being modified up or down by the error signal. The modified signal is fed to an amplifier 99 which operates the drive roller 101. Thus, the drive roller motor advances the tape a predetermined distance corresponding to that during recording for each rotation of the head drum, so that the heads accurately scan the previously recorded track portions.

The effect of the described system is to cause the drive roller 13 to revolve during playback with exactly the same relationship to the rotating drum 18 as it did during the recording process, within narrow limits. Once the head drum is set to the center of the track at the beginning of a playback, the system automatically maintains the relationship constant and the rotary head assembly continuously scans the recorded transverse tracks precisely.

In Fig. 3 shows a more detailed block diagram of a control system. The outgoing video signal is applied to an amplifier 106 where it is amplified and from where it is subsequently applied to a pair of sync separators 107 and 108 ; it then passes to a vertical integrator 109. Pulses are formed with a vertical video synchronization frequency. These pulses are of the type shown in Fig. 7, A.

As already mentioned, the input signal can be derived from the energy source. In this case the local energy source, e.g. B. the 60 Hz network, connected to a pulse shaper 111 , which can be a relaxation oscillation pulse shaper. The output of the pulse shaper is applied to a pulse separator 112 and the pulses appear on the appropriate terminal. A switch 113 is used to turn on either the pulses derived from the video signal or the local signal. The switch routes the selected reference pulses to an amplifier 114. The output of the amplifier is applied to a multivibrator 116 , which is a

Square wave forms. The multivibrator may contain means 117 for adjusting the symmetry of the square wave.

The square wave is applied to a phase separator 118 and the two output signals from the phase separator are applied to the phase comparator 119 . The two signals applied to the phase comparator are square waves that are 180 ° out of phase with one another. The phase comparator 119 is a balanced comparator of the type described here in connection with FIG. 4 will be described. One of the signals applied to the phase comparator is shown in FIG. 7, B. The other signal is identical to this, but shifted in phase by 180 °.

The output signal from the photocell 53 is applied to an amplifier and limiter 120, from there to an amplifier 121 and a pulse shaper 122 . The output of the pulse shaper is fed to frequency dividers 123 and 124 , each of which is used to divide the frequency by two, so that a total of frequency is divided by four. The output of the frequency divider 124 is applied to a phase separator 125 , which is used to form a pair of square waves that are 180 ° out of phase with one another. These square waves are applied to the phase comparator 119 . The phases of the signals applied to the phase comparator from the phase separators 118 and 125 are compared. An output error signal of twice the frequency of the square waves and a direct current component which is dependent on the phase difference are formed. The error signal is shown in FIG. 7, C.

The error signal is applied to an indicating measuring instrument 129 which has a balance adjustment facility 131 . The instrument is used to display the phase difference between the reference signal and the signal generated by the photocell.

The signal on line 128 is also applied to a filter 132 which passes the DC component of the control signal. The magnitude of the direct current signal is limited by a clamp device 133. The clamp signal is fed to an anode clamped reactance stage 134 which is used to control the reactance of the tuned circuit of an oscillator 136. Special devices are provided which ensure that the frequency cannot change instantaneously by more than a predetermined amount. This includes a cathode amplifier 137 which changes the clamp level of a pair of clamps 138 and 139 . Clamps 138 and 139 determine the amount of signal that is applied to diode-coupled oscillator control circuit 141 . Since a fixed change in the state of the oscillator frequency is prescribed by the control voltage, the clamp level rises and falls in order to continuously change the oscillator frequency until the average value of the clamp voltage has such a size that it gives the correct oscillation frequency. The arrangement prevents sudden frequency changes which could exceed the ability to follow the associated arrangement. A voltage regulation tube produces a suitable regulated voltage for the oscillator.

The oscillator 136 is nominally operating at the correct frequency. If there is a phase error between the signals applied to the phase comparator 119 , it is used to change the oscillator frequency in such a direction that the signals are brought back into the correct phase relationship. The clamping circuits prevent the oscillator from experiencing large frequency changes when the two signals are out of phase by a certain amount. The clamp level changes gradually so that the oscillator eventually reaches the correct operating frequency. The sine wave from oscillator 136 is shown in FIG. 7, D.

The sine wave output of the oscillator 136 is applied to a multivibrator 143, which provides a waveform of, £ type shown in Figure 7, and from there to a sawtooth generator 144, a saw shaft from the in F i g. 7, E. The output of the sawtooth generator is applied to a mixer 146 , the voltage of which is controlled by the control tube 147. A second signal is applied to mixer 146 from filter 148 .

The signal from the filter 148 is derived from the output signal of the photocell. The output signal from the pulse shaper 122 is applied to a resonance oscillator 149 after a differentiation 122 a. Thus, each square wave cycle serves to excite the resonant oscillator so that it produces damped oscillations which are out of phase by an amount proportional to the difference between the frequency of the square wave and the natural resonant frequency of the oscillator. The output of the resonance oscillator is applied through an isolating circuit 151 and an amplifier 152 to a phase separator 153 which is used to form a pair of signals phase-shifted by 180 °. These signals are applied to a phase comparator 154 .

Furthermore, a signal from the pulse shaper 122 is applied to the phase comparator. The signal from the pulse shaper 122 is applied to a phase separator 155 which forms a pair of signals which are 180 ° out of phase. These signals are applied to the phase comparator 154 . During operation, the phase comparator then receives pulses directly from the photocell and phase-shifted pulses which have the phase of the resonance oscillator 149 . Any small changes in head speed will result in an error signal from phase comparator 154 which is applied to filter 148 .

The signal from filter 148 is applied to mixer 146 and is used to raise and lower the level of the sawtooth voltage as indicated by arrow 93 in FIG. 8, A indicated. The output from the mixer is applied to a cutter 156 which is used to cut the sawtooth shaft as shown in FIG. 8, B is indicated and explained above. The phase of the trailing edge of the cut signal wave can therefore be changed as indicated by the arrow 97. The cut signal is further amplified by amplifier 157 and applied to a second cutter 158 which cuts in the manner shown by lines 159 and 161 in FIG. 8, C indicated. The cut amplified signal is shown in FIG. 8, D shown. Further reinforcement and cutting create a trailing edge with a sharp rise.

809 569/399

This clipped signal is amplified at 162. The oscillator is a Colpitt oscillator; it contains

limited at 163 and for triggering a multiple the tube 208 and the reference number 209 kators 164 related. The multiplier 164 contains provided frequency-determining circuit. The Freeine Means for adjusting the symmetry of the frequency of the oscillator is controlled in that Wave, as controlled by the adjustable resistor 166 5 of the working circuit of the capacitor 211 or indicated. The output from the multiplier is regulated. The capacitor 211 is directly connected to the connected from a cathode amplifier 167 to a filter 168 resonant circuit 209 when the diodes 212 and from there to the head motor amplifier 92 and 213 are conductive.

lays. By checking the charge or the charging current

It can thus be seen that the described circuit to the capacitor 211 is that of the account a pair of servo loops comprises: an upper capacitor controlled to be consumed reactive current Loop, namely a slow servo loop, which in this way adjusts the resonance frequency of the frequenzum Synchronizing and adjusting the heads in the determining circuit 209 to control or regulate, with reference to the reference frequency, and a lower

Servo loop, which controls the resonance oscillator, the current is controlled by the tube 201. The current Mixers and the cutting devices are comprised and through this tube is served by the error signal serves to control the phase of the output from the oscilloscope, which, as described above, is connected to its grid Correct the lator in such a way that any oscillation is suppressed. The output signal from the tube will be gene of the head drum due to mechanical or by the oppositely polarized diodes 214 and electrical disturbances are attenuated. 20 216 limited so that only certain amounts of electricity

As the drawing shows, the output can be fed to the capacitor 211. Of the output signal from the frequency divider 124 to a filter. Current flows in the illustrated by the curve 217 171 and from there to a cathode amplifier 172 way. During those parts of the cycle where no placed. The output signal from the cathode current flows into the capacitor, the current flows it becomes stronger at the drive roller amplifier 99 through the diodes 212, 213, with which the chip lines. The output signal from the pulse shaper 122 is connected to the stabilizing energy source 218 is going to a cathode amplifier 173 and from then on. The oppositely polarized reference window becomes the drive roller servo amplifier 104 is placed. Except - slowly raised and lowered by means of a circle, this is the output signal from the pulse shaper which contains the tube 219. This tube is in a to a filter 174, to the cathode amplifier 176 30 modified circuit with extreme linearity for and applied to the switch 151 mentioned. Sawtooth wave generation switched. The tube is

A circuit diagram showing a phase comparator and connected so that it receives the signal from the anode of the Oscillator of the type described is shown in FIG. 4 tube 201 receives. When this signal changes shown. The phase comparator with 119 aims to make the tube a larger or smaller one draws; it is in its structure and its power consumption; it is used as a cathode amplifier identical to phase comparator 154. switches to change the voltage at point 221 The output of the multivibrator 116 is sent to the grid, so that the reference window applied to the diodes applied to the tube 181, which changes at a phase voltage. So if the output signal is connected so that signals from ent- out of the tube 201 increases, so the tube 219 lifts opposite polarity capacitive with the terminals 4 ° slowly the reference signal, so that the diodes one 182 and 183 of the phase comparator are coupled. Form "windows" that tend to center The output signal from the frequency divider 124 is added to the error signal. The circuit causes to the grid of the tube 184, which then also provides an instant correction for a vorbeals Phase separator is connected and their outputs were correct low frequency, with the correction from now on the terminals 186 and 187 of the phase comparator 45 takes until the diodes are precisely centered around a are laid. The phase comparator comprises four pairs of continuous signal to be applied to capacitor 211, of resistors 191a, 191Zj; 192a, 192Zj; 193 «, With this new type of phase comparator,

193 Z>; and 194 a, 194 b, which are connected as a bridge circuit, the output frequency is twice the input frequency, the common terminal each having a frequency; it is used to exactly compare two pairs of input pairs with a terminal of the diodes 196, 197, 198 50 signals. The error signal is connected to or 199. The other terminals of the respective diodes then connected to a reactance-controlled oscillator circuit are connected to a common point which nominally operates at the correct frequency. The diodes 196 and 198 are opposite to its frequency but depending on the change in polarity, so that after the common connection between the reference phase and the phase of the connection part, they are conductive, while the diodes 197 55 signal from the photocell are higher or lower - and 199 are polarized in such a way that it is provided by the common. The frequency can be instantly conductive away from the junction. only change by a predetermined fixed amount.

The output signal is applied to the common connection. 5 is another embodiment of FIG

obtained binding parts of the four diodes and shown on the invention that of those of F i g. 3 similar grids coupled to the reactance tube 201. The controversy is borrowed; the same parts are provided with the same reference number 202 and the capacitor 203 are used as a filter sign. The main difference for the signal wave and apply a direct current signal to the two circuits is that the phase control the grid of the tube 201. The one on the line 204 equal 119 a signal of the frequency of the one on it occurring signal corresponds to twice the applied photocell output instead of a divided one Frequency of the 65 frequency applied to the bridge terminals. The signal from amplifier 114 Signal, as already described. is connected to a harmoniously tuned amplifier

The already mentioned clamping or limiter circuit ker 231 placed, which is used to provide an output signal contains the diodes 206 and 207. form which is four times the frequency compared to

that of the input signal. The output is then fed to an amplifier stage 232, which also acts as a limiter, and from there to the phase separator 118 . The phase comparator is at four times the frequency compared to that of 5 F i g. 3 operated; and therefore the system responds more quickly to phase changes.

Splicing and editing pulses can be generated from the horizontal synchronization pulses of the video signal and transferred to the tape to de-linearize each field. In certain cases Does the head "flutter" or the device does not work in synchronism with the reference frequency.

A splice made at such a point in the record gives an output signal which is a Cause a recipient to "roll".

In the case of the in FIG. 5, control pulses are obtained from the pulse shaper 122 and applied to a coincidence gate 234 . If the gate is open as soon as the pulse appears at aa of pulse shaper 122 , an edit pulse is added to and mixed with the control signal. However, when the gate is closed, the edit pulse will not pass and will be recorded. The gate is opened by the vertical sync pulse from amplifier 114 . Thus, when the synchronization pulses are in synchronism and in time with the pulses generated by the photocell, the gate 234 is open to allow a pulse to pass through which is recorded as an edit pulse to mark the end of a field.

A suitable amplifier 114, a harmonically tuned amplifier 231, and an amplifier 232 that also acts as a limiter are shown in FIG. 6 shown. The input signal is sent to the tube

236 reinforced, to one half of the double tube

237 , where it is further strengthened and from where it is attached to the grid of the other half of the double tube. The anode of the double tube 237 includes a resonant circuit 238 tuned to the 4th harmonic. The signal on the line 239 thus receives the frequency of the 4th harmonic. This signal is applied to a limiter (window) 241 , whereby the signal is shaped and then applied to the grating of one half of a double tube 242 where it is amplified, applied to the grating of the second half, again amplified, clipped and to the phase separator is forwarded as described.

A device according to FIG. 3 with a circuit according to FIG. 4, the voltage values and components of which were as follows (the tubes and diodes are named after USA manufacturer type):

Tensions

+ V 250 V.

Tubes

181 5963

182 5963

201 6 AN 8

208 6AN8

214, 216 6 AL 5 voltages

218 0A2

219 12AT7

191 a, 191 b to 194 a, 194 6 each 10 kiloohms

202 1 megohm

251 10 kilohms

252 10 kilohms

253 100 kilohms

254 100 kilohms

256 10 kilohms

257 10 kilohms

258 390 kilohms

259 560 kilohms

261 100 kilohms

262 120 kilohms

263 4.7 megohms

264 100 kilohms

266 250 kilohms

267 3.3 kilohms

268 100 kilohms

269 620 ohm

271 220 kilohms

272 8.2 kilohms

273 5 kiloohms

274 15 kilo ohms

276 150 ohms

277 47 kilohms

278 3.5 kilo ohms

279 47 kiloohms

281 2.2 megohms

Capacitors

203 211 282 283 284 286 287 288 289 291 292 293 294 296 297 298 299

Inductance 301

ΙμΡ 0.0051 1 μΡ ΙμΡ UiF 1 μΡ 0.02 μΡ 6 μΡ 0.1 μΡ 0.004μ 0.015μ 0.03μΡ 0.03 μΡ 47 μΡ 0.047 μ 0.01 μΡ 150

30Η

The device built according to this information works perfectly when recording USA standard video signals.

There was also a device for operation for European standard video signals and with the circuit according to FIG. 5 and 6 built. Its details were as follows (the tubes and diodes are made according to USA manufacturer types designated):

Diodes

Tubes

196 to 199 IN 279

206, 207 IN 432

212, 213 IN 68 A

+ V 250 V.

236 12AT7

237 12AT7

242 12AT7

Claims (1)

15 16 diode comparators for the pulses of both types to 303, 304 IN 279 formation of an error signal for controlling the frequency w, .., quenz of an oscillator are provided whose ι ers at e output energy to feed the second electrical 306 100 kilohms 5 tromotors is used, characterized in that the first-mentioned pulses are used for phase 308 6.8 kilohms synchronization of a second oscillator, 309 470 ohms whose output frequency corresponds to the nominal speed 311 1 megohms of the rotary head arrangement, and that 312 15 kilohms io a comparator for the phases of the first 313 4.7 megohm pulses with the output frequency of the second 314 1 megohm oscillator is provided in order to form a second error 316 4.7 megohm signal that reflects the instantaneous values of the 317 27 kilohms phase changes of both of the former Impulse 318 corresponds to 27 kiloohms 15, and that a device for changing 319 11 megohms that of the phase of the output frequency of the first 320 4.7 megohm oscillato rs corresponding to the second error signal is provided. Capacitors 2 system according to spoke 1, in which the 322 0.1 μΡ ao supply current of the second, the rotary head arrangement 323 0.001 μΡ driving electric motor is supplied by a multivibrator operated with saw 324 25 μΡ toothed shafts 326 0.02 μΡ, characterized in that that the second 327 0.05 μΡ error signal changes the reference voltage level of the saw 328 0.05 μΡ 25 tooth shaft in order to control the phase of the 329 0.05 μΡ feed current of the second motor. τ j tt- -t- + 3. System according to claim 1 or 2, characterized in that the formation of the second error 331 7 to 70 H signal by exciting a second oscillator j ,,. Ai. l · ^^ -... 30 provided resonance oscillator with the impeccable § * * pulses of the first kind 'whose freedom of rotation "einwanairei. speed of the head arrangement is proportional to the plant tamperi" ^ 01S *' where the frequency of the resonance oscillator equal to the nominal frequency of the pulses 1. A magnetic tape recording system in which 35 is the first type and the phase comparison between the magnetic tape on a rotary head arrangement the input and output pulses of the resonance is made by a first electric motor moving past the oscillator. is and the rotary head assembly by a second electric motor is driven, one being considered:
Generator for generating pulses with a 40 German Patent No. 1 014 153, 1023 484; the speed of the turret assembly pro- German Auslegeschrift No. 1 034 684.
proportional frequency to feed the belt drive motor and a source of pulses from a contemplated older patents:
second type with a reference frequency as well as a German patent nos. 1100 682, 1 106 799. For this purpose 2 sheets of drawings 809 569/399 7. 68 © Bundesdruckerei Berlin