JPS6012697B2 - Magnetic tape control method in magnetic recording/reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape control method in a magnetic recording/reproducing apparatus having a function of reproducing a recorded portion once and automatically stopping after the reproduction is completed.

Generally, this type of magnetic recording/reproducing device uses a 4-track, 2-channel system, as shown in Figure 1, where one of the two tracks of the magnetic tape is used to record audio and the other is used to record control signals. By recording a control signal 3 on the control signal track at the same time as recording 2 the audio, when playing back the audio recording,
This can be realized by detecting a control signal and configuring the magnetic recording/reproducing apparatus to switch between the reproduction mode and stop mode depending on the presence or absence of the control signal.

That is, as long as the control signal continues, it is in the playback mode, but when the control signal disappears, it is detected and automatically switches to the stop mode. However, when recording audio on a magnetic tape in a magnetic recording and reproducing apparatus configured in this way, when recording and reproducing are repeated for each segment at an interval A, if the auto-stop time after reproduction is constant, the previous stage If you go back to the recording section and try to play it back, it will automatically stop playing only the previous recording section.

That is, as shown in FIG. 2, the first recording of audio and control signals (hereinafter referred to as both recordings) 2, 3, start t, end t2 → rewind 4, → first double recording 2, . 3. Reproduction of 5. The start of t'. , End t'2 → Auto stop after certain time T → Start t3 of 2nd both recordings 22, 32, end L
→2nd time both records 22, 32 Rewind only part 42
→Start of reproduction 52 of second recordings 22 and 32 t'3,
End t'4 → Auto stop after a certain time T → Start of 3rd both records 23, 33, End t6 → 1st both records 2,,
3. Rewind to part 43 → 1st time both records 2,,3,
Reproduction 5, start t″, end t″2→after a certain period of time T, the state becomes auto-stop.

In this way, if the auto-stop time is always constant and a magnetic tape that has been repeatedly recorded after auto-stop is rewound and played back, the magnetic recording/playback device will auto-stop after playing only the first recorded portion, and the first There arises an inconvenience that it becomes impossible to continuously reproduce the recordings from the beginning to the Nth time.

Therefore, the present invention provides a magnetic recording system in which recording is performed by sequentially extending the time until the next auto-stop when recording after an auto-stop so that it can be continuously reproduced from the first recording to an arbitrary recording. The present invention provides a magnetic tape control method for a playback device.

That is, in the present invention, when recording after auto-stop, the time until the next auto-stop is determined by T, the time of the no-signal area between the first recording part and the next recording part, t, the time of the extended part of this no-signal part, and the auto-stop. If the number of subsequent recordings is N, then T
It is designed to extend according to the relationship +(N-1)t.

By repeating recording after auto-stop under the above-mentioned conditions, the interval A in which the audio and control signals are automatically stopped is sequentially extended on the magnetic tape 1 as shown in FIG.

That is, the auto-stop is performed at time T after the first recording 2, 3, and at the same time as the start of the second recording 22, 32, the auto-stop time is set to the time of the no-signal part between the first recording section and the next recording section. T is extended by a predetermined time t to become T+t, and then, simultaneously with the start of the third recording 23, 33, the auto-stop time is extended by T+2'. Therefore, at the beginning of the Nth recording 2N and 3N after auto-stop, the auto-stop time is extended to time T+(N-1)t, and if the next control signal is detected within this time, recording 2 and 3
If the playback mode can be sustained and the control signal is not detected within that time, then the T0(N-1)
After the time t has elapsed, the magnetic recording/reproducing device is automatically stopped. Next, an example of a circuit implementing the present invention will be described with reference to FIG.

In the figure, 21 is a transistor that is turned on when a positive signal voltage Sv is supplied from the terminal a to the base through the resistor 22 when play gold 0 (not shown) is operated, and the base is connected to the resistor 23. The collector is connected to the power supply voltage Vc of 122V through resistors 14 and 25.
c is supplied and grounded to the outside, and is connected to the base of the transistor 26 at the connection point between the resistors 24 and 25.

The collector of the transistor 26 is supplied with the power supply voltage Vcc through a resistor 27, and the emitter is grounded through a capacitor 28 and connected to the gate of one of the elements constituting the differential circuit 29, such as a field effect transistor (hereinafter abbreviated as FET) 30. It is connected. A transistor 31, a resistor 32 and a diode 33 are connected to the gate of the FET 30.
, 34 is connected to the base of the transistor 31, a bias signal to be described later is supplied from terminal b through a resistor 36, and a power supply voltage Vcc is supplied to the drain of the FET 30 through a resistor 37. At the same time, the base of a transistor 38 whose emitter is connected to the stop mode output terminal c is connected, and its source is connected to the source of the other element of the differential circuit 29, for example, FET 39, and a resistor 40 is connected. is grounded through. A power supply voltage Vcc is connected to the drain of the FET 39, and a constant current circuit 45 consisting of a transistor 41, a resistor 42, and diodes 43 and 44 is connected to the gate, as well as an emitter of a transistor 46 and a capacitor 47. The transistor 46 is turned on by being supplied with a bias signal while a control signal is connected to its base through a resistor 48 from the terminal d and during the rewinding mode of the magnetic tape. Transistor 4 of constant current circuit 45
1 through a resistor 49 and directly to the emitter of the transistor 46 and the capacitor 47.
cc is supplied. 5 Resistor 5 from terminal e to the base
When the control signal disappears during playback, a bias signal is supplied through the transistor 1 and the transistor is turned off.The transistor is supplied with the power supply voltage Vcc through the resistor 52 and is connected to the gate of the FET 39 through the diode 53, and its emitter is grounded. has been done.

According to this configuration, when the play button of the device is operated, the terminal a
When the signal voltage Sv is supplied to the transistor 21, the transistor 21 is turned on, and accordingly, a bias is applied to the transistor 26, the transistor 26 is turned on, the charging circuit of the capacitor 28 is made conductive, and the capacitor 28 is charged. The potential Vc of this capacitor 28 when charging is completed is the power supply voltage Vcc, the resistance values of the resistors 24 and 27 R, and R2.
Then, VC size ratio ×; horse, and Vcc is 22V, so if the constants of R and R2 are 1 plate ○ and IKQ, VC・≠22 × City Ren T main 2
.

It becomes V.

In this state, no bias is applied to the base of the transistor 31 of the constant current circuit 35 and the transistor 31 is off, so that Vc, (20V) is applied to the gate of the FET 30.

This charge starts discharging at the source-to-gate resistance of the FET 30. Since the source-to-gate resistance of the FET is a very high resistance, the charge in the capacitor 28 is hardly discharged and the initial potential is maintained. On the other hand, while the control signal is sustained in the reproduction mode, no bias is applied to the terminal e and the transistor 50 is turned off, and since the transistor 46 is in the reproduction mode and the control signal is sustained, it is applied to the terminal d. - Bias is applied and turned on.
For this reason, the gate of FET 39 is biased by power supply voltage Vcc through resistor 52 and diode 53 while transistor 50 is off, that is, while the control signal is maintained in the regeneration mode, and capacitor 47 is biased through resistor 52 and diode 53. Even when 46 is in the off mode, it is discharged by resistor 52 and diode 53. FE in this state
The gate potential of T39 is Vcc-VcEset±Vcc (22V) when the transistor 46 is on, and Vc when the forward voltage VF of the diode 53 is 0.56V when the transistor 46 is off.

-VF〒22-0.56〒21.4V. Note that the voltage drop across the resistor 52 is calculated as OV, ignoring the gate current of the FET 39. Therefore, whether the transistor 46 is on or off, the gate potential of FET 30 (20 V) and the gate potential of FET 39 (22 V or 21
．． 4V), and in the differential circuit 29 composed of FETs 30 and 39, FET 39 is on and FET 30 is off, so that the transistor 38 is not biased and is off, and no signal is displayed at terminal c. Therefore, as long as the control signal is maintained, the reproduction state of the recording section can be maintained.

When the control signal is cut off in this regeneration state, a bias signal is applied to terminal e, which turns on transistor 5, while the bias signal at terminal d disappears, transistor 46 turns off, and capacitor 47 starts charging. . When this capacitor 47 starts charging, F
The gate potential of ET39 begins to decrease with time, and the FET
When the gate potential of FET 30 is lower than the charging voltage of capacitor 28, FET 39 is turned off, and conversely, FET 30 is turned off.
is turned on and the differential circuit 29 is inverted. Therefore, FET
30 turns on, the transistor 38 turns on, and the terminal c
A signal will appear and the device will automatically stop. That is, the capacitor 47 starts charging, and the relationship between the charging voltage Vc2 and the charging voltage Vc of the capacitor 28 is Vc・>Vc2.
The time at which this occurs is the time T of the above-mentioned no-signal portion.

Here, since the capacitor 47 is charged by a constant current circuit 45 composed of a transistor 41 and diodes 43 and 44, the charging time is very stable and can be set to an arbitrary value.

That is, to select an arbitrary value for the auto-stop time T, the potential of the capacitor 28 is used as a reference, and the selection is made using the charging of the capacitor 47 with respect to that potential. Conversely, if the charging time of capacitor 47 is kept constant, capacitor 2
The same thing can be done by lowering the potential of No. 8 during recording after auto-stop. When the transistor 31 is turned on by applying a bias to the terminal b for a certain period of time during recording after auto-stop, the capacitor 28 is discharged for a certain period of time as a collector current of the transistor 31, and the potential becomes lower than the initial potential. Here, since the transistor 31 constitutes a constant current circuit 35 with diodes 33 and 34, discharge is always performed with a constant current, and the capacitor 2 reduced by this discharge.
8 and the time for charging the capacitor 47 to this potential will naturally be longer than the time T of the no-signal portion between the first recording section and the next recording section. Therefore, if this operation is performed multiple times, for example N times, the potential Vc,'(
The gate voltage of FET30) is lower than the initial potential Vc,
,'=c,1 (discharge voltage of one time)×N, so the auto-stop time TN is the time of no signal between the first recording section and the next recording section T,, the record after auto-stop. The circuit is N". If the value of the potential of the capacitor 28 that decreases in one discharge is converted into time and t is the value, then TN=T, 10(N-
1) t becomes.

As described above, by extending the time of the no-signal area between the first recording section and the next recording section when recording after auto-stop, the rewinding and playback after the number of recordings is performed within the above-mentioned time T-Nt. If the next control signal is detected, playback is continued and the first to Nth recordings can be played back continuously, and if no control signal is detected within the time T-Nt, after that time has elapsed. , the magnetic recording/reproducing device enters an auto-stop state.

In addition, without recording audio recording and control signals on separate tracks on magnetic tape, by using a frequency signal outside the audible range as a control signal, and a white noise of more than 1000 yen, the control signal can be recorded on the audio recording track at the same time as the audio. can be recorded.

As described above, according to the present invention, in a magnetic recording and reproducing apparatus that sequentially records audio and control signals at intervals of auto-stop time, and that automatically stops after the playback is completed during playback of the recording, During recording, the time of the no-signal section between the first recording section and the next recording section is sequentially extended, so that the control signal for the next recording can be generated within the extended auto-stop time during rewinding and replaying after multiple recordings. It is configured to be able to detect and continue playback for all recorded parts without auto-stopping only when playing the first recording, and to control operations such as recording, rewinding, and playback using electrical triggers. It is effective as a magnetic tape control method for magnetic recording and reproducing devices, and is especially used when recording multiple dictations on a single magnetic tape and continuously reproducing these records for writing and typing. Ideal for applying to machines.

-

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory views for explaining the present invention;
The figure is a schematic diagram showing a recording pattern on a magnetic tape recorded by the method of the present invention, and FIG. 4 is a circuit diagram of an example to which the present invention is applied. In the figure, 1 is a magnetic tape, 2 is an audio recording section, 3 is a control signal recording section, and A is an auto-stop time interval section. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In a magnetic recording/reproducing device having a function of simultaneously recording audio and a control signal and, after reproducing the recorded portion, detecting that the control signal is cut off and auto-stopping, when recording after the auto-stop, the following The time until auto-stop occurs is T+, where T is the time of no signal between the first recording section and the next recording section, t is the time of the extension of the no-signal section, and N is the number of recordings after auto-stop.
(N-1)t, and the control signal is detected within the auto-stop time T+(N-1)t during playback of the recording. Control method.