JPS5814411Y2 - Tape recorder erasing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an erasing device for a tape recorder, and more particularly to an erasing device using a DC erasing head as an erasing head.

When erasing unnecessary parts recorded on a magnetic tape in a tape recorder, the recording signal level must be minimized by adjusting the recording level in step 1, or the recording level must be adjusted while the tape recorder is in the recording state. In simple tape recorders that do not have adjustment means, a short plug is inserted into the microphone jack to prevent the recording signal from being applied to the recording head.

When erasing using such a method, if an AC erasing head is used in which alternating current is supplied as the erasing current to the erasing head, the level of noise recorded on the magnetic tape is approximately the same as that of an unused magnetic tape and can be ignored. However, if a DC erase head is used in which a DC current is supplied as the erase current to the erase head, the noise level will increase due to the influence of the AC or DC bias current supplied to the recording head.

This is caused by the difference in the erasing principle in that DC erasing does not perform zero erasing like AC erasing, but erases by keeping the direction of magnetization constant.

In other words, the magnetic material magnetized in a certain direction by the DC erasing head has its magnetization direction not fixed but changed in individual directions by the magnetic force generated by the AC bias current or DC bias current supplied to the recording head, which is a noise signal. becomes.

The present invention attempts to provide a device that improves the above-mentioned problems that arise when a direct current erasing head is used as an erasing head in a tape recorder that does not have a recording level adjustment means. Refer to and explain.

The circuit shown in Figure 1 is an example of using alternating current as the bias for the recording head.
2 is a microphone jack into which a microphone plug is inserted; 2 is an amplifier; 3 is a recording head; and 4 is a recording/playback switch (not shown). Adjustment resistance 5
This is a bias oscillator that supplies a bias current through the transformer 6 and the transistor 7.

Reference numeral 8 denotes a DC erasing head to which a DC current is supplied as an erasing current during a recording operation to perform an erasing operation.

Reference numeral 9 denotes a shorting plug that is inserted into the microphone jack 1 during the erasing operation and grounds the input terminal of the amplifier 2, and its insertion plug portion 10 is a conductor.

Reference numeral 11 denotes a contact piece that comes into contact with the plug portion 10 of the short plug 9 when the short plug 9 is inserted into the microphone jack 1, and is connected to the bias current supply terminal 12 of the recording head 3.

The recording operation of such a circuit will be explained.

When the plug of a microphone (not shown) is inserted into the microphone jack 1 and the recording/playback selector switch (not shown) is switched to the recording side by a recording operation, current is supplied to the bias oscillator 4 and the DC erasing head 8 and the operation is started. As a result, the recording signal obtained from the microphone is inputted from the microphone jack 1, amplified by the amplifier 2, and then applied to the recording head 3 together with the AC bias current output from the bias oscillator 4, and recorded on the magnetic tape. .

The recording operation is performed as described above, but the erasing operation for erasing unnecessary portions will now be explained.

When the button is turned on to record and the shorting plug 9 is inserted into the microphone jack 1 instead of the microphone, not only the input terminal of the amplifier 2 is grounded, but also the bias current supply terminal 12 of the recording head 3 is connected to the action of the contact piece 11. grounded by

Therefore, neither the noise signal generated by the amplifier 2 nor the AC bias current from the bias oscillator 4 are applied to the recording head 3, but only the DC current is supplied to the DC erasing head 8 to perform the erasing operation.

Therefore, the influence from the recording head 3 on the magnetic tape whose magnetization direction is made constant by the erasing head 8 and erased is eliminated, and the noise level is reduced.

The circuit shown in FIG. 2 is an embodiment in which a direct current is used as a bias for the recording head, and the same parts as in FIG. 1 are given the same reference numerals.

In the figure, reference numeral 13 denotes a recording head, to which a direct current bias is applied through a resistor 14.

A recording operation in such a circuit is performed by supplying a DC bias current to the recording head 13 and the DC erasing head 8 through a recording operation, and inserting a microphone into the microphone jack 1.

When the shorting plug 9 shown in FIG. 1 is inserted into the microphone jack 1, the input terminal of the amplifier 2 is grounded by the action of the shorting plug 9, and the bias current supply terminal 15 of the recording head 13 is also grounded.

Therefore, as described above, only the DC erasing head 8 operates to perform an erasing operation with a low noise level.

Comparing the noise level with the conventional erasing method in which the erasing operation was performed by inserting a jumper plug into the microphone jack of 11 in which alternating current or erasing current was supplied as a bias to the recording head, the noise level was 7 dB and 14 dB, respectively. 7) i-goodness was confirmed.

Similarly, when a microphone plug is inserted into the microphone jack 1, the plug is configured not to come into contact with the contact piece 11.

As explained above, according to the present invention, it is possible to minimize the noise level caused by the erasing operation in a tape recorder using a DC erasing head as the erasing head by the simple operation of inserting a shorting plug into the microphone jack. Therefore, the present invention is most suitable as an erasing device for a simple tape recorder that does not have a recording level adjustment means.

[Brief explanation of drawings]

The illustrated circuits are specific examples of the present invention; FIG. 1 shows an embodiment of the circuit using an AC bias head as the recording head, and FIG. 2 shows an embodiment of the circuit using a DC bias head as the recording head. Explanation of main figure numbers, 1...Microphone jack, 2...Amplifier, 3, 13...Recording head, 4...Bias oscillator, 8...・・・・・・
・DC erase head, 9...Short plug, 1
2, 15...Bias current supply terminal.

Claims (1)

[Scope of utility model registration request] In a tape recorder, the tape recorder is equipped with a DC erasing head that performs an erasing operation by being supplied with DC current during a recording operation, a recording head that is supplied with an AC bias or a DC bias, and a microphone jack into which a microphone plug is inserted. An erasing device for a tape recorder, characterized in that a bias current supply terminal of a recording head is grounded when a shorting plug is inserted into a microphone jack.