JPS597135B2 - Magnetic tape tip detection method in cassette tape recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the leading edge of a magnetic tape in a cassette tape recorder.

Generally, in a cassette tape, a leader tape that is not coated with magnetic material is connected to the leading end and end of the magnetic tape, and recording cannot be made to these parts.

For this reason, with this type of cassette tape, it is necessary to run the tape for a while before starting recording, and then wait until the leading edge of the magnetic tape reaches the recording head, with the leader tape wound around.

If this operation is to be performed automatically, the leading edge of the magnetic tape must be detected. Conventional schemes for this detection include:

1 Paste metal foil on the joint between the leader tape and magnetic tape,
This method uses a pair of electrodes to detect the passage of this metal foil.

2 A method that uses a type of leader tape that allows light to pass through it, and places a light emitting element and a light receiving element on both sides of the tape, and detects by blocking the light when the magnetic tape passes.

3 A method in which a suitable signal is recorded in advance on the leading edge of a magnetic tape and detected by a magnetic head.

However, these methods have the following drawbacks.

In the case of No. 1, the glue attached to the metal foil tends to ooze out, which has an adverse effect on long-term storage.

In addition, a dedicated detector is required, and its installation is extremely difficult due to the force setting tape. In case 2, it cannot be used if the leader tape is opaque.

In addition, a dedicated detector is required, and its installation is extremely difficult due to the force setting tape. In case 3, no special detector is required, but the signal must be recorded in advance.

As described above, all of them have major drawbacks, so they have not been put to practical use. The present invention aims to provide a device that is free from such drawbacks and can be put to practical use without any problems. The illustrated embodiment will be described below.

FIG. 1 is a program diagram showing the configuration of the conventional tape recorder circuit. In other words, during recording, a signal from the bias oscillator circuit 5 is supplied to the erasing head 1 to erase the recorded information on the magnetic tape A. At the same time as erasing input terminal a
The input recording signal is amplified by a recording amplifier 4, and sent together with a bias signal from a bias oscillation circuit 5 to a recording/playback head 2 via a recording/playback switch 3, so as to be recorded on a magnetic tape A. Also, during playback, the recording on the magnetic tape A is converted into an electrical signal by the recording/playback head 2, amplified by the playback amplifier 6 via the recording/playback switch 3, and then delivered to the output terminal b. In the recorder circuit, a low frequency oscillation circuit 7 is provided, and its oscillation signal is supplied to the erase head 1 through an erase head changeover switch 8, and the output from the reproduction amplifier 6 is outputted through a muting circuit 9. A detection circuit operates by detecting the signal component of the low frequency oscillation circuit 7 from the output signal of the reproduction amplifier 6.
A control circuit 10 is provided, and the operation of the detection/control circuit 10 switches the erase head changeover switch 8 so that the erase head 1 is returned to the bias oscillation circuit 5 side. During operation, the muting circuit 9 operates to block the signal from the reproduction amplifier 6 to the output terminal b, and furthermore, the detection and control circuit 10 operates to stop the tape running in the tape recorder. Mechanism 1 for obtaining pause or recording status
1 is configured to operate.

When the leading edge of the magnetic tape A is to be detected, the tape recorder is put into a reproducing operation state, and at the same time, the erase head changeover switch 8 is connected to the low frequency oscillation circuit 7 side.

In this way, the oscillation signal from the low frequency oscillation circuit 7 is supplied to the erasing head 1, and the erasing head 1 is ready to record this on the magnetic tape A.

By the way, even in this situation, while the leader tape is initially being wound, it goes without saying that no data is recorded on it. Eventually, when the leading edge of magnetic tape A reaches the position of erasing head 1, it is recorded on it, and the recording is carried out in the next stage of recording.
The reproduction head 2 immediately catches the signal, and the reproduction signal is amplified by the reproduction amplifier 6 and sent to the detection/control circuit 10.

The detection/control circuit 10 is activated by introducing the reproduction signal, whereby the erase switch 8 is switched back to the bias oscillation circuit 5 side, the operation of the muting circuit 9 is stopped, and the reproduction amplifier 6 is switched back to the bias oscillation circuit 5 side. The output of is connected to the output terminal b, and a mechanism 11 for stopping, pausing, or recording the tape in the tape recorder is activated, and the tape is stopped, paused, or put in the recording state. Therefore, the leading edge of the magnetic tape A is automatically detected, and the next operation can be started from the leading edge of the magnetic tape A. FIG. 2 shows a modification of the one shown in FIG. 1, particularly the system of the low frequency oscillation circuit 7. In FIG.

In Fig. 2, 51 is an oscillation transformer in the bias oscillation circuit, and 52 is the bias trap circuit, and the connection between the low frequency oscillation circuit 7 and the bias oscillation circuit 5 is as shown in Fig. 2. As a result, substantially the same function can be provided even without the erase head changeover switch 8. In addition, 71 in FIG. 2 is the low frequency oscillation circuit 7.
This is the power switch. According to the present invention, when using an ordinary tape with an end having a magnetically insensitive leader tape at the leading end of the magnetic tape, when starting recording, etc., the leading end of the magnetic tape following the leader tape is used as the starting point. As a result, the above-mentioned conventional drawbacks can be eliminated, and it can be put to practical use without any problems, and the color tone of the leader tape is irrelevant, and it can be used exclusively for force setting. There is no inconvenience in terms of space or cost due to the insertion of a detector, etc., and there is no adverse effect when using the set tape as it is, which is necessary to lengthen the tape path.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, and Fig. 2 is a circuit diagram of the main part of a modification thereof.
...Erase head, 2...Recording/playback head 7...
...Low frequency oscillation circuit, 8... Erasing head search, 9... Muting circuit, 10...
...Control circuit.

Claims (1)

[Claims] 1 During recording, a signal from the bias oscillation circuit 5 is supplied to the erasing head 1 to erase the existing recording on the magnetic tape A, and at the same time, the recording signal that enters the input terminal a is amplified by the recording amplifier 4, and the bias oscillation circuit 5 to the recording/playback head 2 via the recording/playback switch 3 to record on the magnetic tape A, and
At the time of playback, a tape recorder circuit configured to convert the recording on the magnetic tape A into an electrical signal by a recording/playback head 2, amplify it by a playback amplifier 6 via a recording/playback switch 3, and provide it to an output terminal b. In, the low frequency oscillation circuit 7
is provided so that its oscillation signal is supplied to the erase head 1 via the erase head selector switch 8, and the output from the reproduction amplifier 6 is provided to the output terminal b via the muting circuit 9. , a detection/control circuit 10 is provided which operates by detecting the signal component of the low frequency oscillation circuit 7 from the output signal of the regenerative amplifier 6.
0 switches the erasing head selector switch 8 so that the erasing head 1 is returned to the bias oscillation circuit 5 side, and also causes the muting circuit 9 to operate while the detection/control circuit 10 is operating. playback amplifier 6
The tape recorder is configured to block signals from reaching the output terminal b, and further configured to operate a mechanism 11 for stopping tape running in the tape recorder, pausing, or obtaining a recording state by the operation of the detection/control circuit 10. A method for detecting the leading edge of a magnetic tape in a cassette tape recorder.