SU917209A1 - Device for control of magnetic tape reversing - Google Patents

Description

(54) DEVICE FOR MANAGING THE REVERSE MAGNETIC

RIBBONS

The invention relates to a technique of: magnetic recording, in particular, to control devices for reversing a magnetic tape.

A device for reversing a magnetic tape is known, containing an input bus of a reproduction signal, a frequency selector made on the basis of a high-pass filter, and a block of electronic switches C1)

A disadvantage of the known device is the low reliability of the selection of a single-tone high-frequency control signal by filtering when playing digital information recorded with a high density of signals (with high quality filters of high frequencies and complex electronic k (mutators, which significantly weakens the device). controlling the magnetic recording-playback apparatus to the process of setting it up.

The closest to the preset is a control signal detection device containing an input playback signal bus, a pulse shaper, a counter, a control circuit, an output trigger, and a frequency selector made in

as a rectifier, integrator and comparator t21.

The disadvantage of the second device is that it does not provide: the necessary reliability of the formation of the control signal used to determine the moment of switching on the reverse, the movement of the magnetic tape at the end of the information files. This disadvantage is largely due to climatic instability. The work of its frequency selector, made on the basis of integrating the first chain, and the low resolution of such a selector when allocating a service signal (reverse mark) placed at the ends of information tracks.

20

The object of the invention is to improve the reliability of the control of the magnetic tape reversal.

To this end, the proposed device is equipped with an input bus signal

25 playback connected to the input of the pulse former, the output of which is connected to the input bus of the frequency selector, serially connected by a counter and circuit

Claims (2)

30 coincidence, the output of which is connected to the first input of the output trigger, an additional trigger, the output of which is connected to the installation input of the counter and to the second input of the output trigger, and the first and second inputs to two output buses of the frequency selector, one of which is additionally connected to the counting the input of the counter and the second input of the coincidence circuit. Moreover, the frequency selector is executed in the form of a counting trigger, a waiting multivibrator and two coincidence circuits, the first inputs of which are connected to the outputs of the counting trigger, and the second inputs - respectively to the direct and inverse outputs of the waiting multivibrator, whose input is connected to the output of the counting trigger, and except In addition, the outputs of the coincidence circuits are connected to the output buses of the frequency selector, and the input of the counting trigger to the input bus of the frequency selector. Figure 1 shows a functional diagram of the device for controlling the magnet reverse. a ribbon; 2, the timing diagrams of the device operation are shown. The device contains an input bus 1 of the playback signal, a pulse shaper 2, a frequency selector 3, a counting trigger 4 contents, a waiting multivibrator 5 two schemes b and 7 matches, as well as an additional trigger 8, counter 9, coincidence circuit 10, output trigger and output Ainu 12. Graph 13 corresponds to the signal at the output of pulse generator 2, graph 14 is the signal at the forward output of the counting trigger 4, and graph 15 at its inverse output. Graph 16 is the signal at the forward output of the waiting multivibrator 5, and graph 17 is at its inverse output. Graph 18 signal The mark at the output of circuit 7 matches, and graph 19 is the signal Reset at the output of circuit b matches. Graph 20 - the signal at the output of the additional trigger 8. The device operates as follows. An amplified playback signal is supplied to the input bus 1 of the device. The service signal in the form of a continuous sequence of pulses with a period of following T is pre-recorded at the ends of the information tracks and differs from the information signal by the frequency. The service signal frequency exceeds the maximum frequency of the information sequence of information pulses, for example, the Shaper of 2 pulses converts the linear signal playback to pulse. sequence 13, each pulse, which translates the counting trigger 4 frequency selector 3. By On the positive front of the output signal 14 of the trigger 4, the standby multivibrator 5 is triggered to generate the reference pulses 16 and 17 with a stable and calibrated duration f. The value of fr exceeds the period T of the service signal by 10-20%. During the reproduction, the reference duration D is compared with every second time interval between adjacent reproduction pulses 13. Scheme 6 matches form im-. signal pulses Reset 19 when a signal is played back, the time intervals between adjacent pulses of which are longer than the period T of the service signal. The matching circuit 7 generates the signal pulses of the label 18 when the reverse label is played. For this purpose, the signal 14 from the direct output of flip-flop 4 and the inverse signal 17 of the multivibrator 5 are fed to the inputs of the coincidence circuit b, and the inverted output signal 15 of the flip-flop 4 and the signal 16 from the direct output of the waiting multivibrator 5 arrive at the inputs of the coincidence circuit 7. Trigger 8 is turned on and continuously confirmed. Output potential signal 20 of trigger 8 reliably keeps counter 9 and output trigger 11 closed. When playing service signal 13, Netka 18 pulses switch trigger 8, and then chityvayuts counter 9 which generates an output pulse after counting continuously arriving at it. signal input 20–40 pulses A label whose number depends on the selected capacitance of counter 9. Output trigger 11 switches from the output pulse of the matching circuit 10, which only works if the output pulse of counter 9 and the corresponding Netka pulse is present at its inputs. The output trigger 11 generates the signal command Start Reverse. At the beginning of the reversing mode, which is activated by the command Start of Reverse, the movement of the magnetic tape is slowed down until it is completely stopped, after which the tape begins to move in the opposite direction. During deceleration, the service signal also plays back, but the frequency of the reproduced signal decreases at the same time (Figure 13). As a result, the device generates a datum Reset at the output of the coincidence circuit 6, which includes the trigger 8, thereby locking the counter 9 and the output trigger 11. Claim 1, A device for controlling the reverse of the magnetic tape containing the input signal bus playback connected to the input of the pulse former whose output is connected to the input bus of the frequency selector and a serially connected counter and matching circuit, the output of which is connected to the first input of the output trigger, is different In order to improve the reliability of controlling the reverse of the magnetic tape, an additional trigger is inserted into the device, the output of which is connected to the installation input of the counter and the second input of the output three triggers, and the first and second inputs are connected to the two output buses of the frequency selector, one of which there is an additional connection with the counting input of the counter and the second input of the coincidence circuit. 2. The device according to claim 1, characterized in that the frequency selector is designed as a counting trigger, waiting for a multivibrator and two coincidence circuits, the first BXO-J. The ports of which are connected to the inputs of the counting trigger, and the second inputs, respectively, to the forward and inverse outputs of the receiving multivibrator, the input of which is connected to the output of the counting trigger, while the outputs of the coincidence circuit are connected to the output frequency bus of the frequency selector and the input of the counting trigger to the input frequency bus selector. Sources of information taken into account in the examination 1. UK Patent No. 1488407, cl. G 5 R, publ. 1977. 2. Japanese Patent W 53-2723, cl. 102 E 212, published. 1978 (prototype). (Pui.1 W Phage. 2 iJ