JPH0785407A - Recording current controller for magnetic recording / reproducing apparatus - Google Patents

Abstract

(57) [Summary] [Structure] The serial data outputted from the parallel / serial conversion circuit 5 and passed through the wavelength discriminating circuit 6 is subjected to predetermined processing by the matrix conversion circuit 8 and the flag addition circuit 9 to be written data D _W. To get Also, the serial data is different 5
It is composed of a combination of types of wavelengths. The wavelength discriminating circuit 6 discriminates the wavelength of the serial data, and the wavelength discriminating data obtained as a result is delayed by the delay circuit 7 and input to the current value switching circuit 10. As a result, the write data D _W delayed by the matrix conversion circuit 8 and the flag addition circuit 9 and the wavelength discrimination data are synchronized. Then, the current value switching circuit 10 switches the recording current value based on the wavelength discrimination data. [Effect] Not only is it possible to prevent insufficient erasure of long-wavelength recording signals during overwriting, but it is also possible to improve the power consumption of the recording device and facilitate processing such as equalizing during reproduction. Can be done

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording current control device for a magnetic recording / reproducing device, in which a recording current is switched for each wavelength in a magnetic recording / reproducing device for recording by combining a plurality of recording signals of different wavelengths. Is.

[0002]

2. Description of the Related Art Some magnetic recording / reproducing devices such as a magnetic tape device are configured to perform recording by a recording signal composed of a combination of a plurality of signals having different wavelengths. For example, a recording signal of an AUX track in a digital compact cassette (hereinafter referred to as DCC) device has five types of wavelength 1 as shown in FIG.
It consists of T, 2T, 3T, 4T, and 5T signals, and in the order of shorter wavelength, 1T (6kHz), 2
T (3 kHz), 3T (2 kHz), 4T (1.5 kHz)
z), 5T (1.2 kHz).

In a DCC device, when data is recorded on a magnetic tape recording medium using such a signal,
The recording current having the same value was supplied to the magnetic head all at once regardless of the wavelength. Depending on the magnetic recording / reproducing device,
Instead of directly writing the above signals from the recording head to the recording medium, as shown in (b) of the figure, so-called pulse train recording is performed in which each recording signal is replaced with a signal in which a pulse group with a very short wavelength is replaced. There is one that adopts a recording method called. The pulse train shown in FIG. 9B is an enlarged view of the portion shown in FIG.

[0004]

By the way, in the above-mentioned conventional magnetic recording / reproducing apparatus, as shown in FIG. 8, when the recording signal is recorded on the magnetic tape 42 by the magnetic head 41, the characteristics of the magnetic tape 42 are considered. In the case of a wavelength of 1T, recording is performed at a shallow portion of the magnetic layer 44 formed on the base film 43 because of the short wavelength. In the case of wavelength 5T,
Since the wavelength is long, recording is performed at a deep portion of the magnetic layer 44.

The magnetic tape 4 recorded in this way
In the case of further overwriting 2, the overwriting is easy because the erasing rate is large for the wavelength 1T as shown in FIG. On the other hand, for the wavelength 5T, the erasing rate is small, so that overwriting is not easy. For this reason,
As described above, when writing five kinds of wavelengths with the same value of the recording current, the difference in the erasing rate due to the characteristics of the magnetic tape 42 directly appears as the overwriting difficulty. Therefore, when overwriting with 5T having a long wavelength, there is a problem that the signal is not completely erased but remains. The present invention has been made in view of the above circumstances, and its main object is to improve the erasing rate of long-wavelength signals during overwriting.

[0006]

A recording current control device for a magnetic recording / reproducing apparatus according to the present invention is a magnetic recording / reproducing apparatus for recording information by a recording signal obtained by combining a plurality of signals having different wavelengths. In order to solve the problem, the following measures are taken.

That is, the above-mentioned recording current control device of the magnetic recording / reproducing apparatus has a wavelength discriminating means for discriminating the wavelength of the recording signal, and the recording current value becomes smaller as the recording signal has a longer wavelength based on the discrimination data of the wavelength discriminating means. And a current value switching means for switching the recording current value.

The recording current control device of the magnetic recording / reproducing apparatus of the present invention further comprises a delay means for delaying the discrimination data by a time period in which the recording signal is delayed by the processing after the wavelength discrimination means.

Alternatively, in the recording current control device of the magnetic recording / reproducing apparatus of the present invention, in addition to the delay means, the recording medium on which information is recorded by the recording current switched by the recording current switching means is related to the wavelength. When reproducing with a magnetic recording / reproducing device that records at a constant recording current value, the long-wavelength is set so that the reproduction level of the recording signal with the longest wavelength is equal to or higher than the minimum reproducing level specified by the magnetic recording / reproducing device. A current value setting means for setting the recording current value on the side is provided.

[0010]

In the above structure, when the wavelength of the recording signal is discriminated by the wavelength discriminating means, the recording current switching means switches the recording current value based on the discrimination data obtained as a result. At this time, the recording current value is switched so that the recording current value becomes smaller as the wavelength of the recording signal becomes longer.

As a result, even a recording signal having a large wavelength will not be recorded up to the deep layer portion of the recording medium (magnetic tape). Therefore, when the recording medium recorded in this way is overwritten, it is possible to prevent the long-wavelength recording signal from remaining without being erased. Further, since the recording current value becomes smaller as the wavelength becomes longer, the total recording current value can be reduced.

Further, by delaying the discrimination data of the wavelength discriminating means by the delay means by the time after which the recording signal is delayed by the processing after the wavelength discriminating means, the recording signal and the discrimination data can be transmitted in synchronization. .

A magnetic recording / reproducing apparatus for recording a recording medium on which recording is performed by switching the recording current value according to the wavelength of the recording signal as described above at a constant recording current value regardless of the recording wavelength. When reproducing, the recording current setting means sets the recording current value on the long wavelength side so that the reproduction level of the recording signal of the longest wavelength becomes equal to or higher than the minimum reproduction level specified by the magnetic recording / reproducing apparatus.

As a result, even in the magnetic recording / reproducing apparatus for recording with a constant recording current value regardless of the recording wavelength, when the recording medium recorded by the magnetic recording / reproducing apparatus of the present invention is reproduced, the reproduction level is lowered. There is no inconvenience that reproduction is not performed correctly.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS. In this embodiment, the present invention is applied to the recording unit of the AUX (auxiliary) track in the DCC device as the magnetic recording / reproducing device.

The AUX tracks include tracks 0 to 7
Auxiliary information for managing the audio information recorded on the main tracks up to track number is recorded. As the auxiliary data, a recording position of audio information, an absolute time from the recording start time, TOC (Table of Contents) information, and the like are prepared.

As shown in FIG. 1, this recording section includes a signal processing section 1 and a recording amplifier 2. Signal processing unit 1
, The data stored in the memory 3 is 8/1.
Converted from 8 bits to 10 bits by the 0 conversion circuit 4,
Further, it is converted into serial data by the parallel / serial conversion circuit 5. This serial data has different wavelength 1T
.About.5T (see FIG. 7).

This serial data is input to the wavelength discriminating circuit 6, which will be described in detail later, and the wavelengths 1T to 5T are discriminated here. Then, the serial data that has passed through the wavelength discriminating circuit 6 is input to the matrix converting circuit 8 where it is mixed with the data of the main track. Further, the output data of the matrix conversion circuit 8 is added with a SYNC (synchronization signal) and a control bit described later by the flag addition circuit 9 to become write data D _W , which is sent to the recording amplifier 2. The write clock CK _W necessary for recording the write data D _W is also sent from the signal processing unit 1 to the recording amplifier 2.

As shown in FIG. 2B, the above-mentioned write data D _W has pulses corresponding to tracks 0 to 6, AUX track, and track 7 starting from SYNC. Are basically arranged in a row at regular intervals and are generally used in DCC devices. In addition, three pulses α, which are provided between the pulses corresponding to SYNC and track 0, respectively.
β and γ are control bits for switching the operating state of the recording amplifier 2.

The operation mode of the recording amplifier 2 is set as shown in Table 1 by the above control bits. Therefore, in the example shown in FIG. 9B, only the pulse α is "H", so that tracks 0 to 7 are reproduced and AUX tracks are recorded.

On the other hand, the pulses corresponding to the 0th to 7th tracks respectively represent recorded data. That is, if each pulse is "H", "1" is recorded, and if "L", "0" is recorded.

[0022]

[Table 1]

In the write data D _W , the above pulse train is continuously formed as shown in FIG. The pulse train shown in (b) of the figure is an enlargement of the leading portion of the write data D _W enclosed by an ellipse in (a) of the figure.

On the other hand, the discrimination result in the wavelength discriminating circuit 6 is output as wavelength discriminating data and sent to the delay circuit 7. In the delay circuit 7, the serial data is transferred to the matrix conversion circuit 8
The wavelength discrimination data is delayed by the time delayed by the processing in the flag addition circuit 9. As a result, the serial data and the wavelength discrimination data are sent to the recording amplifier 2 in a synchronized state.

In the recording amplifier 2, the recording current value supplied from the current supply source 11 is changed by the current value switching circuit 10, which will be described in detail later, so that the wavelengths of 1T to 5T are obtained based on the wavelength discrimination data.
It can be switched every time. Then, the data control circuit 12 supplies the write data D _W to the magnetic heads H _{AUX.H 0 to} H ₇ based on the clock CK _W with the recording current amount switched as described above.

The magnetic head H _AUX is a head for recording / reproducing auxiliary data, and forms and scans AUX tracks. The magnetic heads H _{0 to} H ₇ are heads for recording / reproducing audio data, and form and scan tracks 0 to 7 on a magnetic tape (not shown).

Here, the wavelength discriminating circuit 6 will be described.

The wavelength discriminating circuit 6, as shown in FIG.
It includes a flip-flop 13, an inverter 14, an XOR gate 15, a counter 16, a decoder 17, D flip-flops 18 to 22, adders 23 to 26, and a shift register 27.

The D flip-flop 13 has an input terminal D for receiving the serial data S from the parallel / serial conversion circuit 5.
O ₁ is input, and an inverted clock obtained by inverting the clock CK ₁ by the inverter 14 is input to the clock input terminal CK. D flip-flop 13
The XOR gate 15 provided in the subsequent stage is provided with the serial data SO ₁ and the output terminal Q of the D flip-flop 13.
The output signal from and is input.

In the binary counter 16, the output of the XOR gate 15 is input to the clear input terminal CLR, and the above inverted clock is input to the clock input terminal CK. This binary counter 16 is, for example, 74
The HC393 is used to output 3-bit count data from the output terminals Q _A , Q _B, and Q _C.

The D flip-flop 18 is configured such that the above-mentioned 3-bit count data is input to the input terminal D. Further, the D flip-flops 18 to 22 are connected in series with each other with the adders 23 to 26 interposed therebetween.

The decoder 17 has input terminals A ₁ , A ₂ , A
Each of _three output terminals Q _A · Q of the binary counter 16
The output value from the _B · Q _C is adapted to be input.
Further, the decoder 17 outputs the output terminals Y ₀ , Y ₁ , Y ₂ , ... In accordance with the relation of the truth table of Table 2 according to the 3-bit count data inputted to the input terminals A ₁ , A ₂ , A _3.
Decoded data is output from Y ₃ .

[0033]

[Table 2]

The output values of the output terminals Y ₀ , Y ₁ , Y _2, and Y ₃ are supplied to the adders 23 to 26, respectively. As a result, the adders 23 to 26 output the output terminals Y to the outputs of the D flip-flops 18 to 22, respectively.
_The output values of ₀ , Y ₁ , Y _2, and Y ₃ are added together. The output of the D flip-flop 22 is
3-bit wavelength discrimination data TO (TO ₁ , TO ₂ , TO
₃ ) is supplied to the delay circuit 7.

Wavelength discrimination data TO (TO ₁ , TO ₂ , T
As shown in Table 3, O ₃ ) represents wavelengths 1T to 5T when the values are “0” to “4”, respectively.

[0036]

[Table 3]

In the shift register 27, the input terminal A receives the serial data SO ₁ and the clock input terminal CK receives the inverted clock. The shift register 27 is, for example, 8-bit shift register 74HC164 is used, the serial data SO ₁ so as to synchronize with the output of the D flip-flop 22 delays the serial data SO ₁ input serial data SO ₂ Is output from the output terminal Q _E.

Next, the delay circuit 7 will be described. As shown in FIG. 5, like the shift register 27, the delay circuit 7 is composed of shift registers 28 to 30 made up of 74HC164 which are 8-bit shift registers.

In the shift registers 28 to 30, the bit data TO ₁ , TO ₂ and TO ₃ of the wavelength discrimination data are input to the respective data input terminals A, and the clock CK ₁ is input to the clock input terminal CK. It is supposed to be done. These shift registers 28-30 are
Is the input wavelength discrimination data, as 3 is a clock delayed to synchronize with the serial data through the matrix conversion circuit 8 and a flag addition circuit 9 is outputted from the wavelength discrimination circuit 6 from the output terminal Q _C and ing.

Further, the current value switching circuit 10 will be described. As shown in FIG. 6, the current value switching circuit 10 includes an inverter 31, a NOR gate 32, 33 includes a transistor Tr ₁ to Tr _3, a resistor R ₁ to R _6.

The inverter 31 has bit data TO ₁
Is entered. Bit data TO ₁ and TO ₂ are input to the NOR gate 32. The NOR gate 33 has a bit data TO ₁
・ TO ₃ is input.

The emitter of the transistor Tr ₁ to Tr ₃ are grounded via a resistor R ₁ to R _3.
Resistor R ₁ to R ₃ is for determining the recording current in accordance with the wavelength T1～5T, constants of the resistors R ₁ to R ₃ is R ₁
It is set such that ≧ R ₃ > R ₂ . In addition, with a conventional magnetic recording / reproducing apparatus that records a constant value without changing the recording current value for each wavelength, it is possible to reproduce the magnetic tape recorded by the DCC apparatus at a level within a compatible range. The above constants are determined.

That is, when the magnetic tape recorded by the present DCC device is reproduced by the above magnetic recording / reproducing device, the resistances R _{1 to} R ₃ are the lowest reproducing levels specified by the magnetic recording / reproducing device. The recording current value on the long wavelength side is set so as to be equal to or higher than the level, and has a function as a current value setting means.

The collectors of the transistors Tr _{1 to} Tr ₃ are all connected to the emitter of the transistor Tr ₄ of the current supply source 11. Furthermore, the transistor Tr
_{In the case of 1} , the output of the inverter 31 is given to the base via the resistor R ₄ . The transistor Tr ₂ has a resistor R at the base.
The output of NOR gate 32 is provided via ₅ . The output of the NOR gate 33 is given to the base of the transistor Tr ₃ via the resistor R ₆ .

In the current supply source 11, the transistor Tr ₄ is driven by the amplifier 34 and amplifies the current supplied to the magnetic head H _AUX . Also,
The emitter of the transistor Tr ₄ is grounded via the resistor R _A.

The current value switching circuit 10 controls the ON / OFF states of the transistors Tr ₁ to Tr ₃ as shown in Table 4 according to the bit data TO ₁ , TO ₂ and TO ₃ to control the magnetic head H _AUX . The current to be sent is switched. In the current value switching circuit 10 configured as described above, the transistors Tr ₁ to Tr ₃ are turned on / off as described above.
Is controlled so that the recording current value becomes smaller as the wavelength becomes longer with reference to the wavelength 1T.

[0047]

[Table 4]

In the above configuration, the parallel / serial conversion circuit 5 to the serial data SO shown in FIG.
_{When 1} is output, in the wavelength discriminating circuit 6, the serial data SO ₁ is delayed by a half clock in the D flip-flop 13 and input to the XOR gate 15. X
In OR gate 15, the clear signal CLR shown in the same figure (c) is generated by the serial data SO ₁ serial data SO ₁ was half clock delay. The clear signal CLR is given to the clear input terminal of the binary counter 16.

In the binary counter 16, (a) in FIG.
The clock CK ₁ is inverted by the inverter 14 and the inverted clock is counted. As a result, the output terminals Q _A · Q
3-bit count data is output from _B · Q _C and input to the decoder 17 and the D flip-flop 18. The count value represented by this count data is
It becomes as shown in FIG.

In the decoder 17, 4-bit decoded data is generated for the count data due to the relationship shown in Table 2. Further, the count data appears in the A section in a state as shown in (e) of the figure in synchronization with the inverted clock by the D flip-flop 18, and the adder 23 outputs the output value of the output terminal Y ₀ of the decoder 17. Is added.

Thereafter, the output of the adder 23 is sequentially synchronized with the inverted clock by the D flip-flops 19 to 22, and in the states shown in (f) to (h) of FIG. appear. Then, these outputs are added by the adder 24.
26 to 26, output terminals Y ₁ to
The output value of Y ₃ is added. By such processing, D
From the flip-flop 22, wavelength discrimination data TO as shown in (i) of the same figure is output. On the other hand, the serial data SO ₁ is synchronized with the wavelength discrimination data TO by the inversion clock in the shift register 27 and becomes the serial data SO ₂ as shown in (j) of FIG.

In the delay circuit 7, the bit data TO ₁ , TO _2, and TO _{3 of} the wavelength discrimination data are delayed by the shift registers 28 to 30 by 3 clocks of the clock CK ₁ . This is because the serial data SO ₂ is added to the wavelength discrimination data TO and the matrix conversion circuit 8 and the flag addition circuit 9
This is done to give a delay equivalent to the delay caused by the processing in. As a result, in the state where the wavelength discrimination data TO and the serial data SO ₂ are synchronized, the recording amplifier 2
Entered in.

Current value switching circuit 16 in recording amplifier 2
Then, when the transistors Tr _{1 to} Tr ₃ are turned on, the transistor Tr ₄ of the current supply source 11 causes the resistance R
_Since the current I _B is added to the current I _A supplied to _A , the total recording current value increases.

For example, when the recording wavelength is 1T, which is the shortest, (TO ₁ , TO ₂ , TO ₃ ) = (0, 0, 0), so that the transistor Tr as shown in Table 3 and Table 4 is obtained.
_{1 to} Tr ₃ are all turned on. In this case, the amount of increase due to the current I _B is maximum, and therefore the total recording current value is maximum. Conversely, if the recording wavelength is 5T, which is the longest, (T
Since O ₁ , TO ₂ , TO ₃ ) = (1,0,0),
As shown in Tables 3 and 4, transistors Tr ₁ to Tr
All ₃ are turned off. In this case, the current I _B does not flow, and the total recording current becomes only the current I _A and becomes the minimum.

As described above, in the present recording section, the recording current is switched by the recording current circuit 10 according to each of wavelengths 1T to 5T. As a result, when recording with a long wavelength of 5T, the recording current value is minimized, so that recording is not performed in the deep portion of the magnetic layer in the magnetic tape. In addition, the delay circuit 7 allows the wavelength discrimination data TO
Since the write data D _W is synchronized with the write data D _W , both data can be transmitted to the recording amplifier 2 without timing deviation.

By the way, in the structure of this recording unit, the wavelength of 5T is used.
Since the recording current value of 5 is the minimum, when reproducing the wavelength 5T, the reproduction level is 5 nm with the conventional magnetic recording / reproducing apparatus.
It becomes smaller than the reproduction level when T is reproduced. However, since the reproduction level of the wavelength 5T is considerably higher than that of the wavelength 1T (about 5 to 8 dB), the difference between the reproduction levels of the wavelength 1T and the wavelength 5T is small even if the reproduction level of the wavelength 5T is reduced. A reproduction frequency characteristic closer to flat than that of the conventional one can be obtained.

Data detection (reading) during reproduction
Is performed on the long wavelength (wavelength 5T) side without any problem, but is not easy on the short wavelength (wavelength 1T) side. In addition, since each recording / reproducing apparatus has a margin (width) of the reproduction level, the decrease of the recording current on the long wavelength (5T) side has almost no influence on the data detection during reproduction.

[0058]

As described above, the recording current control device of the magnetic recording / reproducing apparatus according to the present invention, in the magnetic recording / reproducing apparatus for recording information by the recording signal obtained by combining a plurality of signals having different wavelengths, The wavelength discriminating means discriminates the wavelength and the current value switching means for switching the recording current value based on the discriminating data of the wavelength discriminating means so that the recording current value becomes smaller as the recording signal has a longer wavelength.

As a result, even a recording signal having a large wavelength will not be recorded in the deep layer portion of the recording medium. Therefore, when the recording medium thus recorded is overwritten, the erasing rate of the recording signal can be improved. Also, since the long-wavelength recording current value can be suppressed to a small value, the total recording current value can be reduced during recording, and the reproduction output difference between the long wavelength and the short wavelength during reproduction can be reduced to make the reproduction output nearly flat. It can have frequency characteristics.

Therefore, if the recording current control device of the magnetic recording / reproducing apparatus of the present invention is adopted, it is possible not only to prevent insufficient deletion of the recording signal of long wavelength at the time of overwriting, but also to reduce the consumption as a recording device. It is possible to improve electric power and easily perform processing such as equalizing during reproduction.

The recording current control device of the magnetic recording / reproducing apparatus of the present invention further comprises delay means for delaying the discrimination data by the time when the recording signal is delayed by the processing after the wavelength discrimination means, whereby the recording signal and the discrimination data are And .. can be transmitted in synchronization with each other, and the recording current value can be reliably switched based on the determination data without any timing deviation.

In the recording current control device of the magnetic recording / reproducing apparatus of the present invention, the recording medium on which the information is recorded is constant regardless of the wavelength by the recording current switched by the recording current switching device in addition to the delay device. When a magnetic recording / reproducing apparatus that performs recording with the recording current value of is used, the long-wavelength side is set so that the reproduction level of the recording signal with the longest wavelength is equal to or higher than the minimum reproduction level specified by the magnetic recording / reproducing apparatus. This is a configuration including current value setting means for setting a recording current value.

As a result, since the recording current value on the long wavelength side is set to be equal to or higher than the minimum reproduction level specified by the magnetic recording / reproducing apparatus as the reproducing device, the recording current value is constant regardless of the recording wavelength. Even in the magnetic recording / reproducing apparatus that performs recording in step 1, the recording medium recorded by the magnetic recording / reproducing apparatus including the recording current control device of the present invention can be normally reproduced.

Therefore, by adopting the recording current control device of the magnetic recording / reproducing device having such a structure, it is possible to maintain compatibility with the magnetic recording / reproducing device which performs recording at a constant recording current value. Play.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a recording unit of an AUX track according to an embodiment of the present invention.

FIG. 2 is an enlarged waveform chart showing write data to be processed in the recording unit of FIG. 1 and a part of the write data.

3 is a block diagram showing a detailed configuration of a wavelength discriminating circuit in the recording unit of FIG.

FIG. 4 is a time chart showing the operation of the wavelength discrimination circuit of FIG.

5 is a block diagram showing a detailed configuration of a delay circuit in the recording unit of FIG. 1 and circuits around the delay circuit.

6 is a circuit diagram showing a detailed configuration of a current value switching circuit in the recording unit of FIG. 1 and a part of a current supply source.

FIG. 7 is a waveform diagram showing a recording signal used in a conventional magnetic recording / reproducing apparatus and a part of the recording signal in an enlarged manner.

FIG. 8 is an explanatory diagram showing how a long-wavelength recording signal and a short-wavelength recording signal are recorded on a magnetic tape by a conventional magnetic recording / reproducing apparatus.

9 is a graph showing the erasing rate at the time of overwriting for each wavelength of the recording signal of FIG.

[Explanation of symbols]

6 Wavelength Discriminating Circuit (Wavelength Discriminating Means) 7 Delay Circuit (Delaying Means) 10 Current Value Switching Circuit (Current Value Switching Means) R _{1 to} R ₃ Resistors (Current Value Setting Means)

Claims (3)

[Claims] 1. A magnetic recording / reproducing apparatus for recording information by a recording signal obtained by combining a plurality of signals having different wavelengths, a wavelength discriminating means for discriminating the wavelength of the recording signal, and a wavelength discriminator based on the discriminating data of the wavelength discriminating means. And a current value switching means for switching the recording current value such that the recording current value becomes smaller as the recording signal becomes longer. 2. The recording current of the magnetic recording / reproducing apparatus according to claim 1, further comprising delay means for delaying the discrimination data by a time period in which the recording signal is delayed by the processing after the wavelength discrimination means. Control device. 3. When a recording medium on which information is recorded by the recording current switched by the recording current switching means is reproduced by a magnetic recording / reproducing apparatus for recording at a constant recording current value regardless of wavelength, the longest It is characterized by further comprising current value setting means for setting the recording current value on the long wavelength side so that the reproduction level of the recording signal of the wavelength becomes equal to or higher than the minimum reproduction level specified by the magnetic recording / reproducing apparatus. 2. A recording current control device for a magnetic recording / reproducing device according to item 1.