JPS626Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape recorder that forms a non-signal recording section in any part of a magnetic tape during recording operation.

Such a conventional tape recorder is shown in FIGS. 1 and 2.
It has a recording circuit as shown in the figure, in which 1 is a microphone input terminal, 2 is an auxiliary input terminal, 3 to 5 are amplifiers, 6 is a recording level adjuster, 7 is a recording bias oscillator, and 8 is a recording bias oscillator 7. 9 is the recording head, 10 is the line output terminal, and _S1 is between the input of amplifier 5, which is connected to the output of amplifier 4 via resistor R in Figure 1, and ground. A normally open switch S2 provided in FIG. ₂ is a normally closed switch provided between the output of amplifier 4 and the input of amplifier 5 in series with resistor R.

In the conventional tape recorder described above, in order to form a non-signal recording section on the magnetic tape during recording operation,
Turn on switch _S1 to ground the signal line,
Alternatively, switch _S2 was turned off to disconnect the signal line. In this way, if a switch is installed on the signal line, if there are multiple signal lines, it is necessary to install multiple switches, and since the signal line is directly switched, it is necessary to wire a shield to prevent externally induced noise. There were some problems, such as the need to place the

This invention was made in view of the above points,
The purpose is to provide a tape recorder that can perform signalless recording with a single switching means regardless of the number of signal lines, and that eliminates the need to take measures to prevent external induction such as shielding. .

Embodiments of the present invention will be described below with reference to FIGS. 3 and 4, in which the same parts as in FIGS. 1 and 2 are given the same reference numerals.

In the tape recorder according to the present invention, a changeover switch _S3 is provided in the recording bias oscillator _{7 '} instead of the switch S1 or _S2 provided in the signal line in the conventional tape recorder.
By turning on the recording bias oscillator 7', the recording bias current obtained at the output of the recording bias oscillator 7' is increased to a greater extent than during normal recording operation.

Normally, the recording bias current I _B of a tape recorder during recording is set to a current value I _B1 corresponding to the peak of the signal line to be recorded when the signal frequency is 333 Hz. Although there are slight differences depending on the type of recording head and magnetic tape, in general, as the recording bias current I _B is increased from zero, the signal level recorded on the tape will rise once, as shown in Figure 4. The signal level reaches a peak, and then increases further, causing the recorded signal level to drop, and this is called the "bias characteristic."

Therefore, in the circuit shown in FIG. 3, switch _S3 is turned on and the recording bias current I _B is changed to I _B shown in FIG.
When the current is increased to ₂ , the signal level recorded on the tape drops rapidly, and a no-signal recording section is formed on the tape regardless of the presence or absence of the signal current I _S .

When the switch _S3 is turned off, the recording bias current _IB returns to the normal bias value _IB1 , and recording is performed on the tape in accordance with the recording signal current _Is on the signal line.

In FIG. 4, ₁ to ₄ are the frequencies of recording signals, and it can be seen that as this frequency increases, the peak of the recorded signal level moves toward the side where the recording bias current is smaller.

As mentioned above, the present invention increases the recording bias current obtained from the output of the recording bias oscillator to form a no-signal recording area on the tape, so the recording bias oscillator is shared by multiple signal lines. The tape recorder requires only one switching means, and since the switching means is not provided on the signal line, it is not necessary to provide a shield or other external induction prevention device, which is extremely effective in practice.

In particular, because the blank recording section is formed by increasing the recording bias current, even if there is residual data on the tape, the increased bias current has the effect of erasing the data, resulting in the creation of a completely blank recording section with no residual data.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams of a conventional tape recorder, FIG. 3 is a circuit diagram of a tape recorder according to the present invention, and FIG. 4 is a graph for explaining the operation of the circuit of FIG. 3. 7'...Recording bias oscillator, _S3 ...Switching means (switch)

Claims (1)

[Scope of utility model registration request] A tape recorder having a recording bias oscillator is provided with means for switching a recording bias current obtained from the output of the recording bias oscillator, and by operating the switching means to increase the recording bias current during recording operation, the recording bias current can be increased on a magnetic tape. A tape recorder characterized in that a no-signal recording section is formed in the tape recorder.