FR2587866A1 - CONNECTING DEVICE FOR TELEVISION RECORDING AND / OR REPRODUCING APPARATUS - Google Patents

Abstract

A. CONNECTION DEVICE FOR A RECORDING AND / OR REPRODUCING TELEVISION DEVICE. B. DEVICE CHARACTERIZED IN THAT IT IS PROVIDED FOR A SECOND DEMODULATOR 21 THE ENTRY OF WHICH IS LIKELY TO BE CONNECTED THROUGH A SECOND HEAD SWITCH 20 ALTERNATIVELY WITH ONE OF THE MAGNETIC HEADS 2, 3, THE FIRST SWITCH OF HEAD 15 BEING SWITCHED DURING THE SYNCHRONISM SIGNAL OF THE TELEVISION SIGNALS, WHILE THE SECOND HEAD SWITCH 20 IS SWITCHED OUT OF THE SYNCHRONISM SIGNAL AREA. C. THE INVENTION CONCERNS CONNECTION DEVICES FOR RECORDING AND OR REPRODUCING TELEVISION APPARATUS.

Description

1.-

  Connecting device for a recording apparatus

  and / or television reproduction ".

  The invention relates to a connecting device

  a device for recording and / or reproducing television, a device in which a plurality of magnetic heads are arranged on the periphery of a head wheel, while a frame distributed over several

  tracks, is recorded on the magnetic tape, a

  positive being, furthermore, provided to compensate for the time errors of the television signals reproduced from the magnetic tape, in which device the input of a first demodulator is capable of being coupled

  alternatively by means of a first switching

  head with one of the magnetic heads.

  When reproducing television signals

  television recorded on tapes, there are time errors, which, to obtain a reproduction

  value, especially when coupling

  products with other signals, are compensated in this

  which is called a time error compensator.

  In the case of recording apparatus with so-called segmented scanning, and in which the

  signals respectively belonging to a frame are re-

  parties on several tracks of the magnetic tape, one 2. -

  switches several times in a frame of a magnetic head

  than on the other. In recording equipment con-

  this occurs within an erase interval

  In this case, due to switching, the horizontal frequency synchronization pulse is lost. For subsequent reproduction of the signals on a control sector, or for the transmission of signals via radio transmitters, this is not inherently troublesome since in the case of known devices, new synchronization signals are

  added to television signals.

  For the determination of time errors, however, it is necessary to detect the horizontal frequency synchronization pulses, to measure their time difference with respect to the pulses of time.

  reference, and correspondingly correct the posi-

  in time of the television signals. The same applies to speed errors, which correspond to changes in time of time errors and in the case of known devices, are compensated by extension or compression by lines of the

  part of a line representing the content of the image.

  But in the known recording and reproducing apparatus, there is not, at the beginning of the first line after the switching of head, pulse

  horizontal frequency synchronization available.

  As a result, in the known apparatuses an extrapolation on the first line of values

  determined for the other lines.

  The object of the invention is to remedy the

  of the known devices and concerns) to this effect

  fet / a device characterized in that there is provided a second demodulator whose input is likely to be

  connected via a second head switch

  alternatively with one of the magnetic heads, the first

  3. The first head switch being switched during the synchronism signal of the television signals, while the second head switch is switched out of

the zone of the synchronism signal.

  The connection device according to the invention with the characteristics defined above has the disadvantage that already for the first line, after switching heads, a determination

  direct time errors is possible.

  Thanks to other characteristics of the

  vention, advantageous additions and improvements

  of the connecting device defined above are possible.

ble.

  Thus, according to a characteristic

  of the invention, the second head switch is switched inside the lines during switching

of the first head switch.

  According to another characteristic of the in-

  vention, the second demodulator is of construction

  simpler than the first demodulator.

  Finally, according to another characteristic

  of the invention, the output of the second demodulator is

  linked to circuits which make it possible to obtain a

  synchronization for a time error compensator.

  An exemplary embodiment of the invention

  is represented as a block diagram on the

  attached and is explained in more detail in the description of

below.

  On the head wheel 1 are arranged two heads placed opposite each other 2, 3. The magnetic strip 4 is guided, by means of return elements 5, 6, so that a cylinder in two parts surrounding the head wheel 1 and not shown

  in the figure, encloses this band along a helix.

  The angle of engagement is then somewhat higher than 4. 1800 so that one of the heads 2, 3 already comes into contact with the band 4 before the other head leaves the band. In the known apparatus, a frame is divided into five or six sections of tracks according to the television standard used. The head wheel 1 is driven by a motor 7, while the belt 4 is moved by

  a capstan device 8 also comprising a

  tor. These two motors are controlled by a circuit of

  command 9, to which is inter alia

  H pulse of horizontal frequency through the input 10. To this control circuit 9 is further applied, so-called a wheel impulse of

  heads, which is generated by a magnetic head 11

  a small permanent magnet 12 is disposed on the head wheel. Through

  head wheel impulse, information on the posi-

  of the head wheel 1, is transmitted

to the control circuit.

  The signals generated by the magnetic heads

  ticks 2, 3 are applied through trans-

  magnetic transmitters not shown, and switches for receiving and retransitting respectively to an amplifier 13, 14. These amplifiers are used to bring the extremely weak signals induced in the heads to an amplitude that can be used for the subsequent processing,

  and to provide frequency slip correction.

  In known recording and reproducing apparatus, the outputs of the amplifiers 13,

  14, are respectively connected to an input of a

  15 at the output of which is connected a demodulator

  16. The demodulated television signals are then

  plotted to a time error compensator 17, known per se, at the output 18 of which appear the signals

  television released time errors.

  So that it does not appear due to the 5.- switching disturbances visible on the image, the operation of the switch 15 is carried out during the

  horizontal frequency suppression intervals.

  In the case of the exemplary embodiment shown, the switching during the horizontal frequency suppression intervals is obtained in that a signal K is delivered by the control circuit 9, this signal taking the logical state one when the switch 15 must be in the top position while it goes to

  the other logical state for the lower position of the com-

  mutator 15. The edges of the signal K lie within the

  line before the horizontal frequency suppression interval, for which switch 15 must be

  to be operated. The sides of the signal K are, however,

  the retransmitted by the synchronized D 19 rocker when a pulse H is applied to its

synchronization input.

  According to the invention, the outputs of the amplifiers

  13, 14 are connected to the inputs of another switch 20, the output of which is connected another demodulator 21. This demodulator 21 can be built more simply than the demodulator 16, because there is no need to impose on him the strict requirements that

  imposed on an organ in the main channel

  a television system.

  To control this other switch 20,

  another D flip-flop controlled by synchronization is provided.

  the data entry of which is also

  plotted the signal K and whose synchronization input receives a pulse H delayed by half a period of

line, for example in 23.

  In the example according to the invention, the edges of the signal K are however shifted, thanks to an appropriate design of the control circuit 9, in the first half of the last lines picked up from 6.-

  the magnetic strip 4 by one of the magnetic heads 2, 3.

  As a result, the switch 20 is already switched before

  the momentum H which appears at the beginning of the first

  the next magnetic head, that is, about the middle of the previous line. The signals of

  carrier frequency corresponding to the pulse of syn-

  synchronization of horizontal frequency, thus arrive

  without interference to the demodulator 21. From these signals,

  modulated, the frequency sync pulse

  rice can then be separated in a circuit 24

  for separation H and to be applied in order to

  time compensator error 17.

7.-

Claims (4)

  1.- Connecting device for an appliance   recording and / or reproduction of television   a device in which a plurality of magnetic heads are disposed at the periphery of a wheel of heads, while   a frame, spread over several tracks, is recorded   on the magnetic tape, a device being further provided to compensate for time errors of the television signals reproduced from the magnetic tape, in which the input of a first demodulator   is likely to be coupled alternately   intermediate of a first head switch with one of the magnetic heads, characterized in that there is provided a second demodulator (21) whose input is connectable via a second head switch (20) alternatively with one of the magnetic heads (2, 3), the first head switch (15) being switched during the synchronism signal   television signals, while the second   head (20) is switched outside the zone of the synchronism signal.   2.- Connection device according to the   claim 1, characterized in that the second switching   Header (20) is switched within the lines during switching of the first head switch (15). 3.- Connection device according to the   claim 1, characterized in that the second demodulation   (21) is of a simpler construction than the first first demodulator (16).   4.- Connection device according to the   claim 1, characterized in that the output of the se-   demodulator (21) is connected to circuits (24)   getting to get a sync signal for a   compensating for time errors (17).