JPS6040986Y2 - magnetic recording and reproducing device - Google Patents

Description

[Detailed description of the invention] The present invention is configured so that recording is performed selectively at at least two different tape running speeds, and during playback, playback is automatically performed at the same tape running speed as the tape running speed at the time of recording. The present invention relates to a magnetic recording/reproducing device.

As a means for automatically switching the tape running speed during reproduction to the same tape running speed as the tape running speed during recording, the one shown in FIG. 1 can be considered.

In FIG. 1, during recording, a control (hereinafter abbreviated as CTL) signal is a 30Hz signal that is generated by converting a vertical synchronization signal (Vss), which is synchronously separated from the video signal, through a 1/2 frequency divider circuit 1, regardless of the tape running speed. The data is recorded on the edge of the magnetic tape 3 by the CTL head 2.

During reproduction, the reproduced CTL signal reproduced from the CTL head 2 is amplified by the CTL amplification circuit 4, and the amplified CTL signal is used as a control signal for the capstan servo system 7 of the reproduction system and also for speed detection. In addition to the f-V conversion circuit 5 used, a Schmitt circuit 6 generates a reproduction mode switching signal Va according to the frequency of the reproduction CTL signal, and this signal is used to switch the speed and gain of the capstan servo system 7. He is in charge.

In the present invention, in the above configuration, when 1/n slow motion playback is performed during playback at each tape running speed, the automatic switching circuit output Va is not reversed and the previous state is maintained. The tape is configured so that after slow motion is released, the tape is immediately run at the original tape running speed.

Now, when performing l/n slow motion playback, the period of the CTL signal obtained from CTL head 2 is 30/n H
z (For example, when performing 1/2 slow motion reproduction, the period of the CTL signal is 15H2).

The 30/n Hz CTL signal serves as a control signal for the capstan servo system circuit 7, and is applied to the f-V conversion circuit 5, which is an automatic switching circuit.

Here, by increasing the time constant of the f-V conversion circuit 5 so that it is n times the same as the slow motion ratio, the output of the f-V conversion circuit 5 always maintains a constant voltage and the next stage The Schmitt circuit 6 is not inverted and maintains its previous state.

Therefore, as in the embodiment of the present invention shown in FIG. If the configuration is such that the predetermined voltage vb is applied to the terminal 9 during slow motion playback, the predetermined voltage vb is applied to the capstan servo system 7 via the switch 8.
is applied to switch the speed and gain to suit slow motion playback.

In addition, when switching from slow motion playback to normal playback from this state, the output of the Schmitt circuit 6 maintains the previous state, so that it immediately returns to the original normal tape running speed in response to the changeover of the changeover switch 8. It is driven.

An embodiment of the f-V conversion circuit 5 of the present invention is shown in FIG. 3, and FIG. 4 shows a waveform diagram of essential parts during its operation.

The regenerated CTL signal is shaped by transistor T1 and resistor R1, and then connected to capacitor C1, diode DI, and resistor R2.
, R3 to create a reset pulse.

Transistor T2 is a switching transistor that performs charging and discharging.

Resistors R4, R5 and transistor T3 are connected during normal driving and
A circuit section for switching between 1/n slow motion playback is provided, and the charging time constant is determined by resistors R7, R8 and capacitor C2.

Capacitor C3, resistor R6, diode D2, and transistor T4 constitute a sample switching circuit section that samples the charging voltage.

Capacitor C4 holds the sampled voltage and
Transistor T5. An f-■ conversion output Vo is obtained from the output stage composed of T6, diode D3, and resistor R9.

During normal running, the slow motion regeneration switching signal v1 applied to one end of the resistor R4 is set to 'LowJ voltage, and during slow motion regeneration, ■1 is set to the rHi voltage.

During normal driving, that is, slow motion playback switching signal v
If 1 is 'LowJ, transistor T3 is ON,
The time constant of the 4-V conversion circuit 5 is determined by the parallel resistance values of resistors R7 and R8 and the capacitor C2. Also, during slow motion playback, the slow motion playback switching signal ■1 is set to 1.
The moment it becomes Hi, transistor T2 turns rOFFJ,
It is determined by resistor R8 and capacitor C2.

The period T of the CTL signal during normal driving is 33.3 m5 (3
0 Hz), and during slow motion playback of 1/n, it becomes n, T.

Now, the f-V conversion output Vo is 1/n from normal driving.
Even when switching to slow motion playback, in order to always maintain a constant voltage, R7, R8C2・R8 C2R7+Rs """'T
This can be realized by setting the n″T condition.

From the above equation 1, this can be easily achieved by setting the relationship between the slow motion ratio and the resistances R7 and R8 as ""RoR...2 8 R+R8.

Here, we have described an example in which the time constant of the f-V conversion circuit is changed by changing the resistance value. The same effect can also be obtained by

The above is the switching method in the f-V conversion circuit 5 according to the present invention, and during 1/n slow motion playback, the automatic switching circuit output power Va is not reversed and the previous state is maintained. The retraction when returning from the 1/n slow motion playback state to the normal running state is also extremely quick.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a conventional tape speed automatic switching device, FIG. 2 is a block diagram showing the basic configuration of the present invention, and FIG. 3 is an electrical diagram showing an embodiment of the main part of the present invention. Figure 4 is an explanatory diagram of the same operation. 2... Control head, 4... Amplifier, 5... f-V converter, 6... Schmitt circuit, 7...・Capstan servo circuit, 8...changeover switch.

Claims (1)

[Scope of utility model registration request] means for selectively switching between first and second different tape speeds during recording; means for recording control signals on the magnetic tape during recording; and means for recording control signals reproduced from the magnetic tape during reproduction. (2) A magnetic recording and reproducing device comprising means for applying the output of the f--(2) conversion circuit to a Schmitt circuit having hysteresis via a conversion circuit, and automatic switching means for determining the tape running speed during recording based on the output of the Schmitt circuit. A magnetic recording and reproducing apparatus characterized in that, during slow motion reproduction, a time constant or a charging/discharging current value of the fV conversion circuit is switched according to a slow motion ratio.