JPH0729109A - Noise reduction device of magnetic recording/reproducing apparatus - Google Patents

Abstract

PURPOSE:To reduce noise generated by magnetic fields applied from surrounding magnetic field generating bodies to a recording head and a reproducing head in a magnetic recording and reproducing apparatus. CONSTITUTION:A signal from an input terminal 25 is recorded by a recording head 16 on a first track 14 of a magnetic tape 12. Simultaneously, the input signal from the input terminal 25 is inverted in its phase by an inverting amplifier 28 and is then recorded on a second track 20 by a recording head 22. The recorded information of the first track 14 is picked up by a reproducing head 18 and is then supplied to an adder 34. The recorded information of the second track 20 is picked up by the reproducing head 24 and is then inverted in the phase by an inverting amplifier 38 and is then supplied to the adder 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reducing noise in a magnetic recording / reproducing apparatus such as a tape recorder.

[0002]

2. Description of the Related Art Conventionally, in a magnetic recording / reproducing apparatus such as a tape recorder, as shown in FIG. 3, recording is performed by amplifying an input signal such as a voice signal with a recording amplifier 2 and then supplying the same to a recording head 4. This is done by recording on the magnetic tape 6 via the recording head 4. For reproduction, a signal obtained by the reproducing head 8 from the magnetic tape 6 is amplified by a reproducing amplifier 10, further amplified by an amplifier (not shown), and then supplied to a speaker.

[0003]

However, in such a magnetic recording / reproducing apparatus, the transmission line from the output side of the recording amplifier 2 to the recording head 4 or the output side of the reproducing head 8 to the reproducing amplifier 10 is formed. Hum noise enters the transmission line, respectively, and the hum noise causes a signal-to-noise ratio (S / N).
There was a problem that the ratio decreased. In particular, no measures have been taken against the hum noise generated in the reproducing head 8 due to the magnetic flux generated by the transformer and the motor provided in the magnetic recording / reproducing apparatus.

[0004]

SUMMARY OF THE INVENTION The present invention aims to reduce the hum noise as described above, and therefore has a recording head and is used for the first and second magnetic recording media.
Writing input signals to each track in opposite phase relation to each other
First and second reading means for reading recorded information from the first and second tracks of the magnetic recording medium in reverse phase relation to each other, and the second writing means and the reproducing head; And an adding means for adding the output signals of the first and second reading means.

Further, the recording information is not read by the first and second reading means in an in-phase relationship, but the recording information is read from the first and second tracks in an in-phase relationship with each other, and these first and second reading information are read. It is also possible to obtain the difference between the output signals of the reading means by the subtraction means.

[0006]

According to the present invention, when the input signal is A, the first
And the recording head of the second writing means has the first and second recording heads.
The signals to be written in the tracks are A and -A, respectively. At this time, the hum noise α is simultaneously written in the first and second tracks. Therefore, the recording information written on the first track is A + α, and the signal written on the second track is −A + α.

From the first and second tracks to the first and second
The recorded information read by the reading means is, for example, A + α
And A-α. Here, the hum noise β is mixed from the reproducing head at the time of reading, but the first and second
Since the output signals of the reading means of the above are in anti-phase relation with each other, the signals supplied to the adding means are A + α + β and A−
It becomes α-β. Therefore, the output signal of the adding means becomes 2 A, and the hum noises α and β generated during recording and reproduction are canceled out.

When the first and second reading means read the record information in the in-phase relationship, the signals supplied to the subtracting means become A + α + β and -A + α + β, and the difference between them is calculated by the subtracting means. Therefore, the output signal of the subtraction means becomes 2A or -2A.

[0009]

EXAMPLE In this example, a tape recorder is used as a magnetic recording / reproducing apparatus, and recording for recording information on a first track 14 of a magnetic recording medium, for example, a magnetic tape 12 as shown in FIG. It has a reproducing head 16 and a reproducing head 18 for reproducing information from the first track 14. Similarly, a recording head 22 for recording information on the second track 20 of the magnetic tape 12 and a second recording head 22
And a reproducing head 24 for reproducing information from the track 20.

The recording heads 16 and 22 are supplied with the same input signal, for example, an analog audio signal from the input terminal 25, but the recording head 16 is supplied with the analog audio signal amplified by the recording amplifier 26. Supplied. The recording head 22 is supplied with the analog audio signal whose phase has been inverted by the inverting amplifier 28 and then amplified by the recording amplifier 30.

The recording amplifiers 26 and 30 have the same phase characteristics. Further, the transmission line from the amplifier 26 to the recording head 16 and the transmission line from the amplifier 30 to the recording head 22 are shaped so that the magnetic flux from a device generating a magnetic field in the vicinity thereof is evenly applied. And the layout is considered.

The output signal generated by the reproducing head 18 is amplified by the reproducing amplifier 32 and supplied to the adder 34. The output signal generated by the reproducing head 24 is amplified by the reproducing amplifier 36, further inverted in polarity by the inverting amplifier 38, and then supplied to the adder 34. The output signal of the adder 34 is output. Terminal 3
6 is supplied.

The reproducing amplifiers 32 and 36 have uniform phase characteristics. Further, the reproducing heads 18 and 24 are arranged so that the same magnetic flux is uniformly applied from the devices that generate the magnetic field around them. Furthermore, the reproducing head 1
Transmission line from 8 to reproduction amplifier 32, reproduction head 2
The shape and arrangement of the transmission lines from 4 to the reproducing amplifier 36 are also taken into consideration so that the same magnetic flux is applied from the devices that generate the magnetic fields around them.

In the tape recorder having such a structure, when the analog signal A as shown in FIG. 2A is supplied to the input terminal 25, the analog signal A is supplied to the recording amplifier 2.
It is amplified by 6 and supplied to the recording head 16.
The recording head 16 records the analog signal A on the first track 14 of the magnetic tape 12. At this time, the hum noise α is transmitted during the transmission from the recording amplifier 26 to the recording head 16. Is superimposed on the analog signal A, and the first track 14 of the magnetic tape 12 is
A + α shown by the solid line in FIG. 2B is recorded (the gain in the amplifier 26 is assumed to be 0 dB for simplicity of description).

The phase of the analog signal A is inverted by the inverting amplifier 28 to become the analog signal -A, which is amplified by the recording amplifier 30 and supplied to the recording head 22. The recording head 22 records the analog signal -A on the second track 20 of the magnetic tape 12. For this recording, the recording amplifier 30 transmits the analog signal -A to the recording head 22. While the hum noise α is applied during the period, −A + α is recorded on the second track 20 as shown in FIG. 2C (the gain in the amplifier 30 is set to 0 d for simplification of description).
B is assumed).

In this way, the first and second tracks 1
The information recorded on the recording heads 4 and 20 is recorded on the reproducing heads 18 and 24.
Is converted into an analog signal by. At this time, an analog signal of A + α should originally be generated in the reproducing head 18, but due to the magnetic flux from the peripheral magnetic field-generating device, the hum noise β as shown by the dotted line in FIG. 2B. Are superimposed and an analog signal A + α + β is generated.
This is amplified by the reproduction amplifier 32 and added by the adder 3
4 is supplied. For simplification of description, the reproduction amplifier 3
Assuming that the gain of 2 is 0 dB, the adder 34 is supplied with the analog signal A + α + β.

Similarly, in the reproducing head 24, an analog signal -A + α + β is generated, which is amplified by the reproducing amplifier 36 and the phase thereof is inverted by the inverting amplifier 38. As shown in FIG. Signal A-α-
β is supplied to the adder 34 (for simplicity of explanation, the gain of the amplifier 36 is assumed to be 0 dB).

As described above, since the analog signal A + α + β and A-α-β are supplied to the adder 34, the analog signal is supplied to the output side of the adder 34 as shown in FIG. 2A occurs. That is, the hum noise α mixed in the analog signal during recording on the first and second tracks 14, 20 and the hum noise β mixed in the analog signal during reproduction from the first and second tracks 14, 20 are both output terminals 40. Completely offset when supplied to
The S / N ratio can be improved.

Although the inverting amplifier 28 is provided on the input side of the recording amplifier 30 in the above embodiment, it may be provided on the output side, or conversely, it may be provided on the input side or the output side of the recording amplifier 26. Good. Further, the inverting amplifier 28 may be removed and one of the recording amplifiers 26 and 30 may have a phase inverting function. Further, the inverting amplifier 28 is removed and the recording amplifier 2
6 and 30 have the same phase characteristics as in the above-described embodiment, and the directions of the signals supplied from the recording amplifiers 26 and 30 to the windings of the recording heads 16 and 22 are reversed, respectively. The phases of the information recorded on the first and second tracks 14 and 20 may be reversed.

Similarly, in the above embodiment, the inverting amplifier 3
Although 8 is provided on the output side of the reproduction amplifier 36, it may be provided on the input side of the reproduction amplifier 36.
May be provided on the input side or the output side of. Further, the inverting amplifier 38 may be removed and one of the reproduction amplifiers 32 and 36 may have a phase inverting function. Further, the inverting amplifier 38 is removed, the phase characteristics of the reproducing amplifiers 32 and 26 are made uniform, and the reproducing heads 18 and 34 are induced in the windings from the first and second tracks 14 and 20 to reproduce. Amplifier 32,
Wiring from the reproducing heads 18 and 24 to the reproducing amplifiers 32 and 36 may be performed so that the signals supplied to the amplifiers 36 have opposite phases.

Although the adder 34 is used in the above embodiment, the inverting amplifier 38 is removed and the output signal of the reproducing amplifier 36 is subtracted from the output signal of the reproducing amplifier 32, or the reproducing amplifier 36 is used. From the output signal of 36, the reproduction amplifier 3
The two output signals may be subtracted.

In the above embodiment, the tape recorder is used as the magnetic recording / reproducing apparatus, but the present invention is not limited to this. For example, a video tape recorder can be used, and the input signal is an analog signal. When a digital signal is used instead, a device such as a magnetic disk can be used.

[0023]

As described above, according to the present invention, the input signals are recorded on the first and second tracks of the magnetic recording medium in opposite phases to each other, and the record information is recorded from the first and second tracks on each other. Even if hum noise occurs in the recording head and the reproducing head due to the magnetic field generated by the peripheral devices, these effects should be removed because it is configured to read in the reverse phase and add them. You can Also, the first
Even when the recording information is read from the second track in the same phase and the difference between the two is obtained by the subtracting means, the influence of the hum noise can be similarly removed and the signal-to-noise ratio can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a noise reduction device in a magnetic recording / reproducing device according to the present invention.

FIG. 2 is a waveform chart of each part of the embodiment.

FIG. 3 is a block diagram of a conventional magnetic recording / reproducing apparatus.

[Explanation of symbols]

 12 magnetic tape (recording medium) 14 first track 16 recording head (first writing means) 18 reproducing head (first reading means) 20 second track 22 recording head (second writing means) ) 24 reproducing head (second reading means) 28 inverting amplifier (second writing means) 34 adder (adding means) 38 inverting amplifier (second reading means)

Claims (2)

[Claims] 1. A magnetic recording medium having first and second writing means for writing input signals in opposite phases to each other on a first and second track of a magnetic recording medium, and the magnetic head having a reproducing head. First and second reading means for reading the recording information from the first and second tracks of the recording medium in reverse phase relation to each other, and an adding means for adding the output signals of the first and second reading means. And a noise reducing device in a magnetic recording / reproducing device comprising: 2. A magnetic recording medium having first and second writing means for writing input signals in opposite phases to each other on a first and second track of a magnetic recording medium, and the magnetic head having a reproducing head. Subtraction for calculating the difference between the first and second reading means for reading the recording information from the first and second tracks of the recording medium in the in-phase relationship with each other and the output signals of the first and second reading means. And a noise reducing device in a magnetic recording and reproducing device comprising.