CN1295679C - Magnetic recording/producing device - Google Patents

Abstract

A helical scan magnetic recording/reproducing device having an MR reproducing magnetic head wherein data to be recorded on a magnetic tape is converted through a modulation circuit into a DC-free code sequence. The device comprises a high-pass filter for attenuating the low frequency components of a reproduced signal picked up by an MR head, and a circuit for demodulating the reproduced signal from the high-pass filter to produce data before being converted into th DC-free code sequence. The low band noise (thermal asperity) produced due to the contact of the magnetic tape with the MR head is removed and a noise-suppressed reproduction output can be obtained. A rotary transformer mounted on a rotary drum is employed as the high-pass filter.

Description

Magnetic recording/reproducing equipment

technical field

The present invention relates to a helical scan type magnetic recording/reproducing apparatus including a magnetoresistive effect head as its reproducing head.

Background technique

Magnetic recording/reproducing devices such as video tape recorders, tape recorders, and computer data storage systems are adapted to a helical scanning method to increase recording density for increased capacity, each magnetic recording/reproducing device adopts as a recording media tape.

Magnetic recording/reproducing apparatuses of the aforementioned type have been required to further increase recording density and increase capacity. In order to further increase the recording density and increase the capacity, a method has been invented which employs a helical scanning type magnetic recording/reproducing apparatus including a magnetoresistance effect magnetic head (hereinafter referred to as "MR head") which The magnetic head functions as a reproducing magnetic head.

The MR head is a magnetic head including a magnetoresistance effect device (hereinafter referred to as "MR device") serving as a magnetic sensor for detecting a magnetic field of a recording medium. In practical use, the MR head has been used as a reproduction head of a hard disk drive. In general, an MR head whose sensitivity is superior to that of an inductive type head can obtain much reproduction output. When an MR head is used as a reproducing head, higher recording density and larger capacity can be realized.

The hard disk drive fixes the MR head on a floating slider for reproducing data while the MR head is floating on the disk. On the other hand, when the MR head is adapted to the helical scanning method, data is reproduced from a magnetic tape in a state where the MR head slides on the magnetic tape.

If the MR head slides on the magnetic tape, many variations occur in reproduction output levels, and although a large reproduction output can be obtained from the MR head, excessive noise is generated. Therefore, this causes a problem that a stable output cannot be obtained. Another problem is that no reproduced signal is output, that is, an out-of-lock frequency occurs. Therefore, a helical scanning type magnetic recording/reproducing apparatus including an MR head serving as a reproducing head has not yet been put into practical use.

Contents of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a helical scanning type magnetic recording/reproducing apparatus including an MR head as a reproducing head and capable of obtaining a stable reproducing output.

The magnetic recording/reproducing apparatus according to the present invention is a helical scanning type magnetic recording/reproducing apparatus comprising: an MR head fixed on a rotating magnetic drum; a high-pass filter; and demodulation means; a rotary transformer. The MR head is fixed on a rotary drum to detect a reproduced signal from a magnetic tape on which data converted into DC-free code trains has been recorded. The high-pass filter attenuates low-frequency components included in the reproduced signal detected by the MR head. The demodulation means demodulates data in a state in which the data has been converted from a reproduced signal to a DC-free code chain, and a low-frequency component of the reproduced signal has been attenuated by a high-pass filter. A rotary transformer is used to transmit a reproduced signal detected by the magnetoresistive effect head fixed on the rotary drum to a stationary part. Wherein, the cut-off frequency of the high-pass filter is not lower than the noise frequency in a low-frequency region, the cut-off frequency is determined by the output resistance of a regenerative amplifier, the mutual inductance of the rotary transformer and the input resistance of a device side circuit, the The reproduction amplifier is used to amplify the reproduction signal detected by the magnetoresistance effect head, and the equipment side circuit is connected to the static part of the rotary transformer, and when reproducing the signal, a magnetic tape and the magnetoresistance effect This noise frequency is generated when the heads come into contact with each other.

According to the above magnetic recording/reproducing apparatus of the present invention, wherein a cutoff frequency of said high pass filter is not higher than the lowest frequency of a band of signals recorded on a magnetic tape.

According to the above magnetic recording/reproducing apparatus of the present invention, wherein when it is assumed that a cutoff frequency of the high-pass filter during reproduction of the signal is f [Hz], and the relative distance between the magnetic tape and the magnetoresistive effect head is When the speed is V[m/s], the following relationship is satisfied:

f[Hz]>50×10 ³ [m ⁻¹ ]×V[m/s].

The above magnetic recording/reproducing apparatus according to the present invention, wherein the cutoff frequency of said high pass filter is 500 kHz or higher.

According to the above-mentioned magnetic recording/reproducing apparatus of the present invention, the data recorded on the magnetic tape is data to which an error correction code has been added, and an error correction means is provided which causes said demodulation means to decode based on the error correction code. The tuned data is subjected to an error correction process.

According to the above magnetic recording/reproducing apparatus of the present invention, further comprising: modulation means for modulating the data recorded on the magnetic tape into data in the form of a chain that does not require a DC code; and a recording head fixed to said rotating magnetic on the drum, and arranged to record the data modulated by the modulating means on a magnetic tape.

The above magnetic recording/reproducing apparatus according to the present invention further includes error code adding means for adding an error correction code to data recorded on the magnetic tape by said recording head.

According to the above magnetic recording/reproducing apparatus of the present invention, wherein a pair of magnetoresistance effect heads is provided as said magnetoresistance effect head, and a predetermined azimuth is set for each of the pair of magnetoresistance effect heads A pair of recording heads is set as the recording head, and a predetermined azimuth angle is set for each of the pair of recording heads. When recording data on a magnetic tape, the pair of recording heads The magnetic head performs no guard band recording when recording data on the magnetic tape, and when reproducing data from the magnetic tape, the paired magnetoresistive effect heads reproduce data passed through the no guard band by the paired recording head. Record the recorded data.

According to the above magnetic recording/reproducing apparatus of the present invention, wherein said magnetoresistance effect head includes a magnetic sensor which detects a magnetic field from a magnetic tape, and which magnetic sensor is a magnetoresistance effect device having a magnetoresistance effect, Also, the magnetoresistance effect head is provided with a soft magnetic film laminated on the magnetoresistance effect device via an insulating film.

According to the above magnetic recording/reproducing apparatus of the present invention, wherein said magnetoresistance effect head is fixed on said rotary drum so that at least a part of said magnetoresistance effect head protrudes to the outer surface of said rotary drum above.

According to the above magnetic recording/reproducing apparatus of the present invention, wherein the magnetic tape sliding surface of the magnetoresistive effect magnetic head has been ground into a cylindrical shape in a sliding direction, and is ground into a cylindrical shape in a direction perpendicular to the sliding direction. shape, wherein the magnetoresistance effect head slides on the magnetic tape along the sliding direction.

According to the above magnetic recording/reproducing apparatus of the present invention, further comprising contact pressure control means for controlling the contact pressure between the magnetic tape and said magnetoresistance effect head.

According to the above magnetic recording/reproducing apparatus of the present invention, further comprising power transmission means for supplying power to said magnetoresistive effect head fixed on said rotary drum.

According to the above magnetic recording/reproducing apparatus of the present invention, wherein said magnetic tape is a magnetic tape having a metal magnetic layer formed on its non-magnetic support member.

According to the above magnetic recording/reproducing apparatus of the present invention, wherein said magnetic tape is a magnetic tape having a carbon type film formed on its surface.

The present invention also provides a helical scanning type magnetic recording/reproducing apparatus, comprising:

a magnetoresistive effect head fixed on a rotating drum and arranged to detect a reproduced signal from a magnetic tape on which data has been recorded converted to a DC-free code chain; a high-pass filter, It is used to attenuate the low-frequency components in the reproduced signal detected by the magnetoresistive effect head; the demodulation device is used to demodulate the data from the reproduced signal in the state before the data has been converted into a state without a DC code chain , the low-frequency component of the reproduced signal has been attenuated by the high-pass filter; and a recording head, which is fixed on the rotary drum and is arranged to record the data modulated by the modulating means on a magnetic tape ; wherein the paired magnetoresistance effect heads are set as the magnetoresistance effect heads, and a predetermined azimuth angle is set for each of the paired magnetoresistance effect heads; the paired recording heads are set as the said recording heads, and a predetermined azimuth angle is set for each of the paired recording heads; when data is recorded on the magnetic tape, said paired recording heads perform no guard band recording; when reproducing data from the magnetic tape, said paired magnetoresistance effect heads reproduce data recorded by said paired recording heads through no guard band recording; and said magnetoresistance effect The width of the magnetic sensor portion of the magnetic tape is larger than the track width of one recording track recorded by the recording head by guard-band-free recording and smaller than the total track width of two adjacent recording tracks.

The present invention also provides a helical scan type magnetic recording/reproducing apparatus, comprising: a magnetoresistance effect magnetic head fixed on a rotating magnetic drum and arranged to detect a reproduced signal from a magnetic tape on which has been recorded on the data converted into no DC code chain; a high-pass filter, which is used to attenuate the low-frequency components in the reproduced signal detected by the magnetoresistive effect head; and demodulation means, which is used to The data is demodulated from the reproduced signal without being converted into a state before the DC code chain, and the low-frequency component of the reproduced signal has been attenuated by the high-pass filter; wherein the magnetoresistive effect magnetic head includes a magnetic sensor device, the The device detects a magnetic field from a magnetic tape and is supported by a pair of magnetic shields.

The present invention also provides a helical scan type magnetic recording/reproducing apparatus, comprising: a magnetoresistance effect magnetic head fixed on a rotating magnetic drum and arranged to detect a reproduced signal from a magnetic tape on which has been recorded on the data converted into no DC code chain; a high-pass filter, which is used to attenuate the low-frequency components in the reproduced signal detected by the magnetoresistive effect head; and demodulation means, which is used to is converted to demodulate data from a reproduced signal without a DC code chain before the state, the low-frequency component of the reproduced signal has been attenuated by the high-pass filter; wherein the magnetoresistance effect magnetic head includes a magnetic sensor device and a permanent A magnet, the device detects a magnetic field from a magnetic tape, and the device is a magnetoresistance effect device with a magnetoresistance effect, and the permanent magnets are arranged on both sides of the magnetoresistance effect device.

According to the above invention, when data is reproduced from the magnetic tape by sliding the magnetic tape and the MR head against each other, the noise contained in the reproduced output from the MR head usually contains various low frequency components. A magnetic recording/reproducing apparatus according to the present invention includes a high-pass filter that attenuates low-frequency components contained in a reproduction signal detected by an MR head. Therefore, the magnetic recording/reproducing apparatus according to the present invention can effectively remove noise contained in the reproduction signal detected by the MR head. Furthermore, the data reproduced by the magnetic recording/reproducing apparatus according to the present invention is data converted into a DC-free chain. Therefore, if the high-pass filter attenuates low-frequency components, data can be reliably reproduced.

Description of drawings

Fig. 1 is a perspective view showing a structural example of a rotary drum unit fixed to a magnetic recording/reproducing apparatus according to the present invention;

Fig. 2 is a plan view showing a schematic structure of an example of a magnetic tape moving mechanism, which mechanism is equipped with a rotary drum unit;

Fig. 3 is a graph showing an example of the spectral distribution of noise caused when data is reproduced by sliding an MR head and a magnetic tape against each other;

Fig. 4 is a sectional view showing the internal structure of the rotary drum unit;

Fig. 5 is the schematic diagram that represents the simple circuit structure of rotary magnetic drum and its peripheral circuit;

Fig. 6 is a diagram showing a circuit equivalent to a region from a reproduction amplifier connected to a rotary part of a resolver to a device side circuit connected to a device side circuit the stationary part of the resolver;

Fig. 7 is a perspective view showing an example of the MR head fixed on the rotary drum;

Figure 8 is a plan view showing the MR head as seen from the surface over which the magnetic tape slides;

Fig. 9 is a schematic diagram showing a state in which the MR head works so as to reproduce data from the magnetic tape;

Fig. 10 is a graph showing an example of a signal reproduced by an MR head from a magnetic tape on which no data has been recorded, in a state where the signal has not yet been passed through a high-pass filter;

Fig. 11 is a graph showing an example of a signal reproduced by an MR head from a magnetic tape recorded with data in a state where the signal has not yet been passed through a high-pass filter;

Fig. 12 is a graph showing an example of a signal reproduced by an MR head from a magnetic tape recorded with data in a state where the signal has been passed through a high-pass filter.

Detailed ways

Embodiments of the present invention are now described.

A magnetic recording/reproducing apparatus according to the present invention is a magnetic recording/reproducing apparatus using a magnetic tape as a recording medium. For example, the device according to the invention is used as a video tape recorder, tape recorder or data storage system for a computer. A magnetic recording/reproducing apparatus according to the present invention is a helical scanning type magnetic recording/reproducing apparatus equipped with a rotary drum for recording/reproducing data. An MR head is used as a reproducing head fixed on the rotary drum.

1 and 2 show a structural example of a rotary drum unit fixed to a magnetic recording/reproducing apparatus according to the present invention. FIG. 1 is a perspective view schematically showing the structure of a rotary drum unit 1 . FIG. 2 is a plan view schematically showing a tape moving mechanism 10 including the rotary drum unit 1. As shown in FIG.

As shown in Figure 1, the rotary drum unit 1 comprises: a cylindrical static drum 2; a cylindrical rotary drum 3; a motor 4, which is used to rotate the rotary drum 3; paired induction heads 5a and 5b, which are fixed on the rotary drum 3; and pairs of MR heads 6a and 6b, which are fixed on the rotary drum 3.

It should be noted that a so-called upper drum rotary drum unit 1 comprising a rotary drum 3 fixed to a stationary drum 2 is now described. The present invention can be widely used in helical scanning type magnetic recording/reproducing apparatuses. Therefore, the type of the rotary drum unit is not limited. For example, a so-called center drum type rotary drum unit comprising a rotary drum sandwiched by a pair of stationary drums may be used.

The stationary drum 2 of the rotary drum unit 1 is a non-rotating drum, ie a drum clamped as described above. A guide rail portion 8 is formed in a side surface of the stationary drum 2 in a direction in which the magnetic tape 7 moves. As will be described later, the magnetic tape 7 moves along the guide rail portion 8 when a recording/reproducing operation is performed. The rotary drum 3 is arranged such that its central axis coincides with that of the stationary drum 2 .

The rotary drum 3 is a drum that is rotated at a predetermined rotational speed by the motor 4 when an operation for recording/reproducing the magnetic tape 7 is performed. The rotary drum 3 is formed into a cylindrical shape having substantially the same diameter as the stationary drum 2 . The rotary drum 3 is arranged such that its central axis coincides with that of the stationary drum 2 . A pair of induction heads 5 a and 5 b and a pair of MR heads 6 a and 6 b are fixed on the surface of the rotating drum 3 opposite to the stationary drum 2 .

Each of the inductive heads 5a and 5b is a recording head in which a pair of magnetic cores are connected to each other by a magnetic gap. In addition, a coil is wound on the magnetic core. When recording data on the magnetic tape 7, the induction heads 5a and 5b are used. The inductive magnetic heads 5a and 5b are fixed on the rotary magnetic drum 3 so that the angle formed by the inductive magnetic heads 5a and 5b relative to the center of the rotary magnetic drum 3 is 180°. In addition, the magnetic gap portions of the induction heads 5a and 5b protrude above the outer surface of the rotary drum 3. As shown in FIG. The induction heads 5a and 5b are arranged to have opposite azimuth angles so that guard-band-less recording of the magnetic tape 7 is performed at a predetermined azimuth angle. The azimuth angle is preferably 5° to 30°.

The aforementioned inductive heads 5a and 5b may be known recording heads which have been used in conventional helical scanning type magnetic recording/reproducing apparatuses. Specifically, it is preferred to use a so-called MIG (Metal In Gap in Magnetic Gap) magnetic head, which includes a soft magnetic material such as a magnetic core made of ferrite, and also includes a magnetic core formed on the soft magnetic material. on the metal magnetic film. In addition, the paired magnetic cores are connected to each other so that the metal magnetic films are oppositely arranged through a magnetic gap.

On the other hand, the MR heads 6a and 6b are reproducing heads which include MR devices serving as magnetic sensors for detecting magnetic signals from the magnetic tape 7 . When reproducing data from the magnetic tape 7, the MR heads 6a and 6b are used. The MR heads 6a and 6b are fixed on the rotary drum 3 such that the MR heads 6a and 6b make an included angle of 180° with respect to the center of the rotary drum 3 . Furthermore, the portion provided with the MR device protrudes above the outer surface of the rotary drum 3 . The MR heads 6a and 6b are configured to have similar azimuths to those of the inductive heads 5a and 5b in order to detect magnetic signals recorded on the magnetic tape 7 at a predetermined azimuth without guard bands.

The magnetic recording/reproducing apparatus records data on and reproduces data from the magnetic tape 7 by sliding the magnetic tape 7 on the rotary drum unit 1 .

Specifically, when performing a recording/reproducing operation, as shown in FIG. . Thus, recording/reproducing operations are performed on the rotary drum unit 1 .

When recording data on the magnetic tape 7, the paired induction heads 5a and 5b slide relative to the magnetic tape 7. Thus, the inductive heads 5a and 5b perform guard-band-less recording operations. When data is reproduced from the magnetic tape 7, the paired MR heads 6a and 6b slide relative to the magnetic tape 7. Thus, the data recorded by the paired induction heads 5a and 5b are reproduced by the MR heads 6a and 6b.

The magnetic tape 7 subjected to the recording/reproducing process of the rotary drum unit 1 can pass through the guide rollers 14 and 15 , the capstan pulley 16 and the guide roller 17 to move to the winding roller 18 . That is, the capstan 16 moves the magnetic tape 7 at a predetermined tension and a predetermined speed, and the capstan 16 is rotated by the capstan motor 19 . Then, the magnetic tape 7 is brought into contact with the inductive magnetic heads 5a and 5b and the MR heads 6a and 6b, which are fixed on the rotating rotary drum 3, so as to slide under a predetermined contact pressure. Then, the magnetic tape 7 is wound on the winding roller 18 .

As described above, the rotary drum unit 1 is provided with the capstan 16, which is rotated by the capstan motor 19 and serves as a contact pressure control device for controlling the induction heads 5a and 5b and the MR heads 6a and 6b. Contact pressure with tape 7.

When the magnetic tape 7 is moved as described above, the rotary drum 3 is rotated by the motor 4 as indicated by arrow A in FIG. 1 .

On the other hand, the magnetic tape 7 moves along the guide rail portion 8 of the stationary drum 2 so as to slide obliquely on the stationary drum 2 and the rotary drum 3 . That is, as shown by arrow B in FIG. 1, the magnetic tape 7 moves in a predetermined tape moving direction along the guide roller portion 8 from the tape entrance portion so as to slide on the stationary drum 2 and the rotating drum 3. Then, as indicated by arrow C in FIG. 1, the magnetic tape 7 is moved to the tape outlet portion.

During the data reproduction operation of the MR heads 6a and 6b, when the MR heads 6a and 6b slide relative to the magnetic tape 7, frictional heat is generated by the contact and sliding between the MR heads 6a and 6b and the magnetic tape 7. The influence of frictional heat changes the temperature of the MR heads 6a and 6b (hereinafter referred to as "MR head temperature"). In general, the MR devices fixed on the MR heads 6a and 6b are temperature dependent. If the head temperature changes, noise will be generated in the reproduced output. The noise caused by the temperature variation of the MR head is called asperity.

Fig. 3 shows an example of the spectrum distribution of noise, which is generated when data is reproduced by operating the MR heads 6a and 6b with the magnetic tape 7 to slide relative to each other. In FIG. 3, a hatched portion corresponds to thermal irregularities. As shown in Figure 3, thermal irregularities are concentrated in the low frequency region. The reason for this is that the change in head temperature is a low-frequency change. Specifically, assuming that the relative velocity between the MR heads 6a and 6b and the magnetic tape 7 is V[m/s], the thermal unevenness area is not higher than one by 50×10 ³ [m ^-1 ]×V[m/s] ] indicates the frequency. If the relative velocity V between the MR heads 6a and 6b and the magnetic tape 7 is 10 m/s, the thermal unevenness is not higher than 500 kHz.

As will be described later, low-frequency components in the reproduced signal are attenuated, thereby removing thermal unevenness, and obtaining a signal in which noise components are attenuated.

During data reproduction by sliding the MR heads 6a and 6b relative to the magnetic tape 7, if foreign matter is introduced between the MR heads 6a and 6b and the magnetic tape 7, so-called dropout occurs. As will be described later, this embodiment has a structure in which, if a dropout of a reproduced signal occurs, an error correction process is performed so that the original data is reproduced.

Preferably, the diameter of the rotary drum 3 of the rotary drum unit 1 is about 10 mm to 60 mm. In addition, the rotational speed of the rotary drum 3 is about 500 rpm to 8000 rpm. The diameter and rotational speed of the rotating magnetic drum 3 can be changed arbitrarily to meet the requirements of the system. If the diameter of the rotary drum 3 is large and the rotational speed is high, the relative speed between the induction heads 5a and 5b and the MR heads 6a and 6b and the magnetic tape 7 increases. Thus, the surfaces of the inductive heads 5a and 5b and the MR heads 6a and 6b on which the magnetic tape slides are easily damaged. Thus, its life is shortened. In particular, the wear of the surfaces of the MR heads 6a and 6b on which the magnetic tape slides tends to affect the MR heads 6a and 6b. If the surface on which the tape slides is worn, performance is greatly reduced. Therefore, it is preferable to set the diameter and rotational speed of the rotary drum 3 to values with which the MR heads 6a and 6b can have a practically satisfactory life and which satisfy the above-mentioned ranges.

The internal structure of the rotary drum unit 1 will now be described with reference to FIG. 4 .

As shown in FIG. 4, a rotating shaft 21 is inserted into the central portions of the stationary drum 2 and the rotating drum 3. As shown in FIG. It should be noted that the stationary drum 2, the rotating drum 3 and the rotating shaft 21 are made of conductive material so that the aforementioned components are electrically connected to each other. The stationary drum 2 is grounded.

Two bearings 22 and 23 are provided inside the sleeve for the stationary drum 2 . In this way, the rotary shaft 21 is rotatably supported with respect to the stationary drum 2 . That is, with respect to the stationary drum 2 , the rotary shaft 21 is rotatably supported by the bearings 22 and 23 . On the other hand, a flange 24 is provided for the inside of the rotary drum 3 . A flange 24 is fixed to the upper end of the rotary shaft 21 . In this way, the rotary drum 3 can rotate synchronously with the rotation of the rotary shaft 21 .

The rotary drum unit 1 incorporates a rotary transformer 25 which is a non-contact signal transmission unit for transmitting signals between the stationary drum 2 and the rotary drum 3 . The resolver 25 includes a stator core 26 and a rotor core 27 , the stator core is connected to the stationary magnetic drum 2 , and the rotor core 27 is connected to the rotating magnetic drum 3 .

The stator core 26 and the rotor core 27 are made of a magnetic material, such as ferrite, which is formed into a ring and arranged around the rotating shaft 21 . The stator core 26 is provided with: a pair of signal transmission rings 26a and 26b corresponding to the pair of inductive magnetic heads 5a and 5b; a signal transmission ring 26c and a power transmission ring 26d corresponding to the pair of MR heads 6a and 6b. correspond. The aforementioned rings are arranged concentrically. Similarly, the rotor core 27 is equipped with: a pair of signal transmission rings 27a and 27b, which correspond to the pair of inductive magnetic heads 5a and 5b; a signal transmission ring 27c and a power transmission ring 27d, which correspond to the pair of MR heads 6a Corresponds to 6b. The aforementioned rings are arranged concentrically.

The power transmission rings 26d and 27d supply the power required to operate the paired MR heads 6a and 6b. That is, the rotary drum unit 1 includes power transmission rings 26d and 27d of the rotary transformer 25, which constitute power supply means for supplying power to the MR heads 6a and 6b.

The rings 26 a , 26 b , 26 c , 26 d , 27 a , 27 b , 27 c and 27 d are loop coils which are wound around the rotation shaft 21 . The rings 26 a , 26 b , 26 c , and 26 d of the stator core 26 are arranged opposite to the rings 27 a , 27 b , 27 c , and 27 d of the rotor core 27 . The resolver 25 transmits signals and power to and from the rings 26a, 26b, 26c, and 26d of the stator core 26 and the rings 27a, 27b, 27c, and 27d of the rotor core 27 in a contactless manner.

The resolver 25 attenuates only low-frequency components contained in a signal that must be transmitted, and transmits only high-frequency components. That is, the resolver 25 transmits signals and power in a non-contact manner, and also functions as a high-pass filter to attenuate low-frequency components in signals that must be transmitted. Therefore, the resolver 25 also functions as a high-pass filter to attenuate low-frequency components in the reproduced signals detected by the MR heads 6a and 6b. Thereby, it is possible to remove thermal unevenness contained in the reproduced signal detected by the MR heads 6a and 6b.

A motor 4 for rotating the rotary drum 3 is connected to the rotary drum unit 1 . The motor 4 includes a rotor 28 and a stator 29, the rotor 28 being a rotating part and the stator 29 being a stationary part. The rotor 28 is attached to the lower end of the rotating shaft 21, and is equipped with an operating magnet 30. On the other hand, the stator 29 is connected to the lower end of the stationary drum 2 and is provided with an operating coil 31 . When a current is passed through the operating coil 31, the rotor 28 rotates. Thereby, the rotating shaft 21 connected to the rotor 28 rotates. Synchronized with this rotation, the rotary drum 3 fixed to the rotary shaft 21 rotates.

The recording/reproducing operation performed by the rotary drum unit 1 will now be described with reference to FIG. 5, which schematically shows the electrical circuit of the rotary drum unit 1 and its peripheral circuits.

When the rotary drum unit 1 is operated to record data on the magnetic tape 7, a current is supplied to the motor 4 to operate the coil 31. Thus, the rotary drum 3 rotates. In a state where the rotary drum 3 is rotating, as shown in FIG. 5, a recording signal is supplied from the external circuit 40 to the encoder 41. As shown in FIG.

The encoder 41 supplied with the recording signal from the external circuit 40 decodes the recording signal, and adds a predetermined error correction code. That is, the encoder 41 functions as an error correction code adding means which decodes the recording signal from the external circuit 40 and adds the error correction code to the data which must be recorded on the magnetic tape 7. The data to which the error correction code is added by the encoder 41 is supplied to a modulation circuit 42 .

The modulation circuit 42 modulates the data from the encoder 41 into data in the form of a DC-free chain. The modulation operation by this modulation circuit 42 may be performed by any device as long as the device can perform an operation of modulating data into data in a DC code chain-free form.

Specifically, such modulation may be a modulation for performing so-called 8-10 conversion so that data to which an error correction code has been added and formed a block of codes is converted into 10-bit code data every 8 bits so as to form code data in which limits DC-free code chaining of the spectrum in the low frequency region. As an alternative to it, this modulation can be used to perform so-called 8-9 conversion modulation so that the data to which an error correction code has been added and form a block code is converted into 9-bit code data every 8 bits in order to form the limit A DC-free code chain for the spectrum in the low frequency region. As an alternative to it, a mirror square (Miller2) method can be used.

The data in the form of a DC-free chain output from the modulation circuit 42 is supplied to the recording amplifier 43 or the recording amplifier 44 . In synchronization with the rotation of the rotary drum 3 , the modulation circuit 42 supplies data to the recording amplifier 43 or the recording amplifier 44 . That is, the modulation circuit 42 supplies data to the recording amplifier 43 corresponding to the inductive head 5a while the inductive head 5a is recording data. Simultaneously with the recording of data by the induction head 5b, the modulation circuit 42 supplies data to the recording amplifier 44 corresponding to the induction head 5b.

The recording amplifier 43, which has been supplied with data in the form of a DC-free chain from the modulation circuit 42, amplifies the recording signal corresponding to the above data to a predetermined level to supply the recording signal to the signal transmission ring 26a of the stator core 26. Similarly, the recording amplifier 44, which has been supplied with data in the form of a DC-free chain from the modulation circuit 42, amplifies the recording signal corresponding to the above data to a predetermined level to supply the recording signal to the signal transmission loop of the stator core 26. 26b.

As described above, the paired induction heads 5a and 5b are arranged to be opposite to each other with respect to the center of the rotary drum 3 at an angle of 180°. Therefore, the induction heads 5a and 5b alternately record data with a phase difference of 180°. That is, the time at which the recording signal is supplied from the recording amplifier 43 to the signal transmission ring 26a corresponding to the induction head 5a and from the recording amplifier 44 to the signal transmission ring corresponding to the induction head 5b is alternately switched with a phase difference of 180°. 26b provides the time to record the signal.

The recording signal supplied to the signal transmission ring 26 a of the inductive head 5 a is transmitted to the signal transmission ring 27 a of the rotor core 27 in the non-contact manner. The recording signal transmitted to the signal transmission ring 27a of the rotor core 27 is supplied to the induction head 5a. Thus, the induction head 5 a records data on the magnetic tape 7 .

Similarly, the recording signal supplied to the signal transmission ring 26b corresponding to the inductive head 5b is transmitted to the signal transmission ring 27b of the rotor core 27 in the contactless manner. The recording signal transmitted to the signal transmission ring 27b of the rotor core 27 is supplied to the induction head 5b. Thus, the induction head 5 b records data on the magnetic tape 7 .

When the rotary drum unit 1 is operated to reproduce data from the magnetic tape 7, a process similar to recording data is performed so that a current is supplied to the operating coil 31 of the motor 4. Thus, the rotary drum 3 rotates.

In a state where the rotary drum 3 is rotating, as shown in FIG. 5, a high-frequency current is supplied from an oscillator 51 to a power driver 52. As shown in FIG. The high frequency current from the oscillator 51 is converted into a predetermined AC current by the power driver 52, and then supplied to the power transmission ring 26d of the stator core 26.

The AC current supplied to the power transmission ring 26d of the stator core 26 is transmitted to the power transmission ring 27d of the rotor core 27 in a contactless manner. The AC current transmitted to the power transmission ring 27 d of the rotor core 27 is rectified by the rectifier 53 so as to form a DC current supplied to the voltage regulator 54 . The aforementioned AC current is set by voltage regulator 54 to a predetermined voltage level.

As the detection current, a current set to a predetermined voltage level by the voltage regulator 54 is supplied to the paired MR heads 6a and 6b. It should be noted that a reproduction amplifier 55 for detecting signals transmitted from the MR heads 6a and 6b is connected to the paired MR heads 6a and 6b. And the current from the voltage regulator 54 is supplied to the reproduction amplifier 55 .

As will be described later, the MR heads 6a and 6b are equipped with MR devices each having a resistance value which changes according to the strength of an external magnetic field. The magnetic field of the signal generated by the magnetic tape 7 changes the resistance of the MR devices of the MR heads 6a and 6b. This changes the voltage of the detection current. The reproduction amplifier 55 detects the change in voltage to output a signal corresponding to the change in voltage as a recording signal.

It should be noted that when the reproducing amplifier 55 detects and outputs the reproduced signal, the reproducing amplifier 55 performs a switching operation in synchronization with the rotation of the rotary drum 3 . That is, while the MR head 6a is reproducing data, the reproducing amplifier 55 outputs the recording data detected by the MR head 6a. While the MR head 6b is reproducing data, the reproduction amplifier 55 outputs a recording signal detected by the MR head 6b.

As described above, the paired MR heads 6 a and 6 b are disposed at an angle of 180° relative to the center of the rotary drum 3 . Therefore, the MR heads 6a and 6b alternately perform reproduction operations with a phase difference of 180°. That is, the reproduction amplifier 55 alternately switches the timing of outputting the reproduced signal from the MR head 6a and the timing of outputting the reproduced signal from the MR head 6b with a phase difference of 180°.

The reproduced signal from the reproduced amplifier 55 is supplied to the signal transmission ring 27 c of the rotor core 27 . The reproduced signal is transmitted to the signal transmission ring 26c of the stator core 26 in a contactless manner. The resolver 25 attenuates the low frequency components of the signal that must be transmitted and transmits only the high frequency components. That is, resolver 25 transmits the signal in a contactless manner, and also functions as a high-pass filter.

Therefore, when the reproduced signal is transmitted from the signal transmission ring 27c of the rotor core 27 to the signal transmission ring 26c of the stator core 26, the reproduction signal detected by the MR heads 6a and 6b is formed as a signal free of low frequency components. This leads to a situation where, if thermal unevenness is included in the output from the MR heads 6a and 6b, the thermal unevenness is removed when transmitting the reproduced signal from the signal transmission loop 27c to the signal transmission loop 26c.

Since data in the form of a DC-free chain is recorded on the magnetic tape 7, if the resolver 25 attenuates low-frequency components, loss of data can be prevented.

The reproduction signal transmitted to the signal transmission ring 26c of the stator core 26 is supplied to the reproduction amplifier 56 so that the signal is amplified by the reproduction amplifier 56 . Then, the reproduced signal is supplied to the detection circuit 57 . The detection circuit 57 detects data in the form of a code chain from the reproduction signal supplied to the reproduction amplifier 56 . The data recorded on the magnetic tape 7 is data converted into a DC-free chain. Therefore, the data detected by the detection circuit 57 is data in the form of a DC-free chain.

The data detected by the detection circuit 57 is supplied to the demodulation circuit 58 to demodulate the data. If the data has been subjected to, for example, 8-10 bit conversion by the modulation circuit 42 when the data has been recorded, the demodulation circuit 58 performs the opposite conversion, ie, 10-8 conversion of the data detected by the detection circuit 57 . If the data has been subjected to, for example, 8-9 conversion by the modulation circuit 42 when the data has been recorded, the demodulation circuit 58 performs the reverse conversion, ie, 9-8 conversion of the data detected by the detection circuit 57 . As described above, the demodulation circuit 58 functions as a demodulation means that demodulates data in a state before switching from a reproduced signal to a state without a DC code chain, and the low-frequency component of the reproduced signal has been suppressed. The resolver 25 acts as a high-pass filter to attenuate.

The data demodulated by the demodulation circuit 58 is supplied to a decoder 59 to be decoded, and then output to the external circuit 40 . The decoder 59 performs an error correction process based on the error correction code added to the data by the encoder 41 when recording the data. That is, the decoder 59 functions as an error correction means to perform an error correction process on the data demodulated by the demodulation circuit 58 based on the error correction code, which is performed based on the error correction code.

The error correction process is performed as described above. Therefore, if a reproduced signal dropout is caused by inclusions introduced between the MR heads 6a and 6b and the magnetic tape 7, the original data can be reproduced with a small amount of reproduced signal dropout.

If constitute this circuit as shown in Figure 5, then paired inductive head 5a and 5b, paired MR head 6a and 6b, rectifier 53, voltage regulator 54 and reproduction amplifier 55 are fixed on the rotary magnetic drum 3, so that they rotate together with the rotary drum 3 . On the other hand, an encoder 41, a modulating circuit 42, recording amplifiers 43 and 44, an oscillator 51, a power driver 52, a reproducing amplifier 56, a detecting circuit 57, a demodulating circuit 58 and a decoder 59 are provided on the rotary drum unit. 1, or made in the external circuit, wherein the external circuit and the rotary drum unit 1 are formed independently.

A portion of the circuit shown in FIG. 5 is shown in FIG. 6 in the region from the reproduction amplifier 55 connected to the rotating part of the resolver 25 to the device side circuit connected to the stationary part of the resolver 25.

Symbol E _i is the output voltage from the reproducing amplifier 55, _R1 is the output resistance of the reproducing amplifier 55, L is the mutual inductance of the rotary transformer 25, _R2 is the input resistance of the equipment side circuit connected to the static part of the rotary transformer 25, E ₀ is the output voltage from the rotary drum unit 1 .

Assuming that the frequency of the signal to be transmitted is f, the input/output characteristics of the equivalent circuit can be expressed by the following formula (1):

E ₀ /E ₁ =(m ² +p ² ) ^-1/2 (1)

where m=(R ₁ +R ₂ )/R ₂ , p=R ₁ /(2πfL)

Assuming that the cutoff gain is -3dB from the peak value, the input/output characteristics are expressed by the following equation (2) when m=p _(f=f1) :

E _0(f=f1) /E _0(f=∞) ＝-3dB＝2 ^-1/2 (2)

Since m=p, the cutoff frequency f1 in the low frequency region can be expressed by the following equation (3):

f ₁ =(R ₁ R ₂ )/{2πL(R ₁ +R ₂ )} (3)

Therefore, the cutoff frequency f ₁ in the low frequency region is determined by R ₁ , L and R ₂ . That is, the output resistance R1 of the reproduction amplifier ₅₅ connected to the MR heads 6a and 6b, the mutual inductance L of the resolver 25, and the input resistance _R2 of the equipment side circuit determine the cutoff frequency of the high-pass filter.

Thus, the above-mentioned value is adjusted so that the cutoff frequency of the high-pass filter is not lower than the frequency of noise (thermal unevenness) in the low-frequency region, which is generated when the magnetic tape and the MR heads 6a and 6b are in contact with each other at the time of reproducing the signal. .

Specifically, if it is assumed that the relative velocity between the MR heads 6a and 6b and the magnetic tape 7 is V[m/s], the frequency band of thermal irregularities is not higher than about 50×10 ³ [m ^-1 ]×V[m /s]. Therefore, adjust the values of R ₁ , R ₂ and L so that the cutoff frequency f ₁ of the high-pass filter satisfies the following equation (4):

f ₁ [Hz]＞50×10 ³ [m ^-1 ]×V[m/s] (4)

Thereby, noise (thermal unevenness) in the low frequency region generated when the magnetic tape and the MR heads 6a and 6b are brought into contact with each other during signal reproduction can be removed. Therefore, a signal with a limited noise component can be obtained. It should be noted that the cut-off frequency _f1 of the high-pass filter can be made no higher than the lowest frequency of the band of signals which must be recorded on the magnetic tape. Thereby, unnecessary attenuation of desired signals can be prevented.

In the example shown in FIG. 5, resolver 25 is used as a high-pass filter. However, it is also possible to provide a high-pass filter separately from the resolver 25 . In the above case, the high-pass filter may be provided in a section from the MR heads 6a and 6b to the demodulation circuit 58. Also in the above case, thermal unevenness can be removed from the reproduced signal, which is similar to the structure in which the resolver 25 is used as a high-pass filter.

The MR heads 6a and 6b fixed on the rotary drum 3 will now be described with reference to FIGS. 7 and 8. FIG. It should be noted that these MR heads 6a and 6b have the same structure except for opposite azimuth angles. Therefore, the following description is made with the MR heads 6 a and 6 b collectively referred to as the MR head 6 .

The MR head 6 is a magnetic head for detecting a magnetic signal from the magnetic tape 7 by utilizing the magnetoresistance effect. Generally, an MR head has a higher sensitivity and a larger reproduction output than an inductive head that uses electromagnetic induction to record/reproduce data. Therefore, the MR head is suitable for high-density recording operations. Therefore, when the MR head 6 is used as a recording head, a higher density recording operation can be performed.

As shown in FIGS. 7 and 8, the MR head 6 includes: a pair of magnetic shields 61 and 62 made of a soft magnetic material such as nickel-zinc polycrystalline ferrite; The pair of magnetic shields 61 and 62 are supported by an insulator 63; permanent magnetic films 65a and 65b, which are provided on both sides of the MR device portion 64; and conductor portions 66a and 66b, which are connected to the permanent magnetic films 65a and 65b. As shown in FIG. 8, the MR device portion 64 is disposed at a predetermined azimuth angle θ with respect to the sliding direction D of the MR head 6 relative to the magnetic tape 7. As shown in FIG. It should be noted that the insulator 63 is omitted in FIG. 7 . FIG. 8 shows the MR device portion 64 and its peripheral portion.

The gap between the magnetic shield 61 and the magnetic shield 62 is generally called a "reproduction gap". Preferably, the width _t1 of the reproduction gap is determined to be suitable for the signal wavelength recorded on the magnetic tape 7 . Specifically, the above-mentioned width is about 0.1 μm to 0.2 μm in order to increase the recording density required in recent years.

The MR device portion 64 of the MR head 6 is formed by laminating an MR device having a magnetoresistance effect, a SAL (soft adjacent layer), and an insulating film interposed between the MR device and the SAL film layer.

MR devices are made of a soft magnetic material, such as nickel-iron, which has a resistance that is changed by the strength of an external magnetic field. Preferably, the thickness of the MR device is about 20nm-60nm. The magnetic saturation of MR devices made of nickel-iron is about 600emu/cm ³ to 1000emu/cm ³ . The SAL film layer applies a vertical bias magnetic field to the MR device through a so-called SAL bias method. MR devices are made of magnetic materials such as permalloy, which have large coercive force and high magnetic permeability. The insulating film insulates the MR device and the SAL layer from each other to prevent electrical shunt current loss. The insulating film is made of an insulating material such as tantalum.

The permanent magnet films 65a and 65b provided on both sides of the MR device portion 64 apply a horizontal bias magnetic field to the MR device. The permanent magnet films 65a and 65b are provided in contact with both side surfaces of the MR device. In this way, a so-called joint structure (abut structure) is formed. The permanent magnet films 65a and 65b are made of a magnetic material such as cobalt-nickel-platinum or cobalt-chromium-platinum, which has a large coercive force and magnetic permeability.

Conductor portions 66a and 66b connected to the permanent magnet films 65a and 65b are formed on both side surfaces of the magnetic shield 62 so that the ends of the conductor portions 66a and 66b are exposed. The ends of the conductor portions 66a and 66b are formed as terminals 67a and 67b, and these two terminals 67a and 67b supply the detection current to the MR device from the outside. That is, from the terminals 67a and 67b, the detection current is supplied to the MR device provided for the MR device portion 64 via the conductor portions 66a and 66b and the permanent magnet films 65a and 65b.

The MR device portion 64 of the MR head 6 is substantially rectangular in plan. The minor axis of the MR device portion 64 is made substantially perpendicular to the tape sliding surface 68 . In addition, the MR device portion 64 is supported by a pair of magnetic shields 61 and 62 via an insulator 63 so that either side surface of the MR device portion 64 is exposed to a magnetic tape sliding surface 68 .

The tape sliding surface 68 is ground into a cylindrical shape in the direction D in which the magnetic tape 7 slides relative to the MR head 6 to expose either side surface of the motor 4 to the tape sliding surface 68 . In addition, the tape sliding surface 68 is ground in a cylindrical shape in a direction perpendicular to the sliding direction D. As shown in FIG. That is, the magnetic tape sliding surface 68 of the MR head 6 is made spherical so that the protrusion of the MR device portion 64 and its peripheral portion is maximized. The MR head 6 is fixed on the rotary drum 3 so that the MR device portion 64 including the MR device and its peripheral portion protrude above the outer surface of the rotary drum 3, and the MR device portion 64 is a magnetic sensor portion.

When the MR head slides relative to the magnetic tape 7 , the magnetic tape 7 is mainly supported by the rotary drum 3 and the air flow generated by the rotation of the rotary drum 3 . The MR head 6 containing the MR device portion 64 and its peripheral portion is made to contact and slide relative to the magnetic tape 7 (wherein the MR device portion 64 and its peripheral portion protrude above the outer surface of the rotary drum 3), so that The tape 7 forms a tent shape. As described above, the tape sliding surface 68 of the MR head 6 has been ground into a cylindrical shape to maximize the protrusion of the MR device portion 64 and its peripheral portion. Furthermore, the MR head 6 has been fixed to the rotary drum 3 so that the cylindrically ground portion protrudes above the outer surface of the rotary drum 3 . Therefore, the contact characteristic between the MR device portion 64 and the magnetic tape 7 can be improved.

When the above-mentioned MR head 6 is operated to reproduce data from the magnetic tape 7, the magnetic tape 7 slides on the MR device portion 64 as shown in FIG. Fig. 9 is an enlarged schematic diagram showing the magnetic tape 7 and the MR device portion 64 of the MR head 6 in which data has been recorded on the magnetic tape 7 with a predetermined azimuth angle θ with no guard band recording, and the MR device of the MR head 6 The portion 64 and its periphery slide on the magnetic tape 7 . FIG. 9 schematically shows the state of a reproduction process performed by the MR head 6. As shown in FIG. Arrow D shown in FIG. 9 indicates the direction in which the MR head 6 slides on the magnetic tape 7 .

When reproducing data from the magnetic tape 7, under the state that the magnetic tape 7 is sliding on the MR device portion 64, a detection current is supplied to the MR device provided for the MR device portion 64 through the permanent magnetic films 65a and 65b, wherein the permanent magnetic film 65a and 65b are connected to both ends of the MR device portion 64 and the conductor portions 66a and 66b.

Specifically, a terminal 67a provided for the end of the conductor portion 66a is connected to the voltage regulator 54 . Then, a predetermined voltage is applied from the voltage regulator 54 to supply the detection current. Further, terminals 67b provided for the ends of the conductor portions 66b are connected to the rotary drum 3. As shown in FIG. The rotating drum 3 is electrically connected to the stationary drum 2 via a rotating shaft 21 . In addition, the stationary drum 2 is grounded. Therefore, the terminal 67b provided for the conductor portion 66b is grounded through the rotating drum 3, the rotating shaft 21 and the stationary drum 2.

When the detection current is supplied to the MR device portion 64 in a state that the magnetic tape 7 is sliding, the resistance value of the MR device provided for the MR device portion 64 is changed according to the magnetic field generated by the magnetic tape 7 . This changes the voltage of the detection current. When the voltage change of the detection current is detected, the magnetic field of the signal generated by the magnetic tape 7 is detected. Therefore, the data recorded on the magnetic tape 7 is reproduced.

The MR device used in the MR head 6 may be a device having a magnetoresistance effect. For example, a so-called giant magnetoresistance effect device (GMR device), which is fabricated by laminating multiple thin films, can be used to achieve a higher magnetoresistance effect. The method of applying a bias magnetic field to the MR device is not limited to the SAL bias method. For example, any of the following methods may be used, including: permanent magnet bias, shunt bias, self-bias, interchange bias, adjustable barber pole, The division device method or the servo bias method. As for the giant magnetoresistance effect and various bias methods, see "BASE AND APPLICATION OFMAGNETORESISTANCE EFFECT HEAD" published by Maruzen and translated by Kazuhiko Hayashi.

When reproducing the data recorded on the magnetic tape 7 by the MR head 6, if the width _t2 of the magnetic sensor portion of the MR head 6 (hereinafter referred to as "head width _t2 ") is smaller than the track width _t3 of the recording track, Then the reproduced output is lowered. If the recording head width _t2 is larger than the total track width _t4 of two adjacent recording tracks, crosstalk will be excessively generated. Therefore, as shown in FIG. 9, it is preferable that the recording head width _t2 is larger than the track width _t3 of the recording track on which data has been recorded by the inductive heads 5a and 5b by the guard-band-free recording method. Furthermore, it is preferable that the recording head width t ₂ is smaller than the total width t ₄ of two adjacent recording tracks. When the reproduction head width _t2 is set as described above, a large reproduction output with limited crosstalk can be obtained.

The magnetic tape 7 used in a recording/reproducing apparatus including the above-mentioned rotary drum unit 1 will now be described.

The magnetic tape 7 includes: a non-magnetic support member having a structure in which a plastic film is formed into a tape shape; and a magnetic layer formed on the non-magnetic support member.

Preferably, the coercive force of the magnetic layer is 1000-2000 Oe, the squareness ratio is 0.6-0.9, and the remanence is 200emu/cm ³ -300emu/cm ³ . As the magnetic layer satisfying the above characteristics, a metal magnetic layer made of a metal magnetic material is preferably used.

Specifically, it is preferable to use evaporation, sputtering or ion plating to form a ferromagnetic metal magnetic material such as cobalt, cobalt-oxygen, cobalt-chromium, cobalt-nickel, Cobalt-iron-nickel or cobalt-nickel-chromium. It should be noted that the properties of the magnetic layer depend on the material and method of formation. That is, when the magnetic layer is formed by evaporation and by changing the amount of oxygen introduced during the evaporation process, remanence, squareness ratio, etc. can be controlled.

There is a tendency that even the reproduction output is enlarged in proportion to the thickness of the magnetic layer. It should be noted that the above effects can be improved up to a thickness of about 1/4 of the recording wavelength. When the thickness is greater than 1/4 of the recording wavelength, the reproduction output cannot be significantly increased if the thickness is increased. If the magnetic layer is too thick, it may cause a problem of reduced yield. Therefore, the thickness of the magnetic layer is preferably about 20 nm to 200 nm.

The magnetic film may be formed from a single-layer film, from a multilayer film obtained by laminating multilayer films, or from a composite film obtained by laminating multilayer films made of different materials.

The magnetic tape 7 is not required to be composed of a non-magnetic support and a magnetic layer. That is, the magnetic layer may be formed after forming a base coat layer on the non-magnetic support. As a modification thereof, an undercoat may be formed on the reverse side of the non-magnetic support member. Another structure may also be employed in which a protective film is formed on the magnetic layer for protecting the magnetic layer. As a modification thereof, a top coat layer containing a lubricating material and A rust-resistant material.

When a protective film is formed on the magnetic layer, the protective film may be a carbon-type film, such as a diamond-shaped carbon film or made of CrO ₂ , Al ₂ O ₃ , BN, Co oxide, MgO, SiO ₂ , Si ₃ O _4. Thin films made of SiN _x , SiC, SiN _x -SiO ₂ , ZrO ₂ , TiO ₂ or TiC. From the viewpoint of improving the sliding properties between the MR head 6 and the magnetic tape 7, it is preferable that a diamond-shaped carbon film (so-called DLC film) is used for the protective film. The protective film may be a single layer film, a multilayer film made by laminating multilayer films, or a composite film made by laminating multilayer films made of different materials.

Finally, the output of the reproduced signal obtainable when the above-mentioned MR head 6 is used to execute the helical scanning method will now be described. A specific example thereof is shown in FIGS. 10 to 12 . It should be noted that the MR head 6 includes MR devices made of nickel-iron. The width _t1 of the recording gap is 0.17 μm, the recording head width _t2 is 18 μm, the track width _t3 of the recording track is 11 μm, the azimuth angle θ is ±25°, and the relative velocity between the MR head 6 and the magnetic tape 7 is V is 10m/s.

Fig. 10 shows a reproduced signal obtained from the MR head 6 when no data is recorded on the magnetic tape 7, and Fig. 10 shows the signal before passing through the high-pass filter. As shown in Fig. 10, the reproduced signal has a relatively significant change in the low frequency region. These changes are mainly caused by thermal irregularities.

Fig. 11 shows a reproduced signal obtained from the MR head 6 when existing data is recorded on the magnetic tape 7, and Fig. 10 shows the signal before the signal passes through a high-pass filter. Fig. 12 shows the reproduced signal after passing through the high-pass filter. It should be noted that the cutoff frequency of the high pass filter is 500kHz.

As shown in FIG. 11, the reproduced signal before passing through the high-pass filter includes lower frequency noise components. The above facts are mainly caused by thermal irregularities. Thermal unevenness has been removed from the reproduced signal when the reproduced signal is passed through a high pass filter. Thus, as shown in FIG. 12, a satisfactory reproduced signal in which noise is limited can be obtained.

Preferably, the cutoff frequency of the high-pass filter is approximately the highest frequency of the thermal irregularity. It should be noted that this cutoff frequency must not be higher than the lowest frequency of the recorded signal band. Specifically, it is generally preferable that the cutoff frequency of the high-pass filter is about 500 kHz to 1000 kHz, but it must be determined in accordance with the relative speed between the MR head 6 and the magnetic tape 7 and the like.

Industrial Applicability

As described above, the magnetic recording/reproducing apparatus according to the present invention can obtain a stable reproduced output because thermal unevenness can be removed from the reproduced signal. Therefore, according to the present invention, an MR head capable of obtaining a high sensitivity and a large reproduction signal can be used as a recording head, which is fixed to a helical scanning type magnetic recording/reproducing apparatus. Thereby, the recording density can be further increased, and the capacity can be further increased.

Claims (3)

1. A helical scanning type magnetic recording/reproducing apparatus comprising: a magnetoresistive effect head fixed to a rotating drum and arranged to detect a reproduced signal from a magnetic tape on which data has been recorded converted to a chain that does not require a DC code; A high-pass filter, which is used to attenuate low-frequency components in the reproduced signal detected by the magnetoresistance effect head; demodulation means for demodulating data from a reproduction signal whose low-frequency components have been attenuated by said high-pass filter before the data has been converted to a state without a DC code chain; and a recording head fixed on said rotary drum and configured to record data modulated by said modulating means on a magnetic tape; wherein a pair of magnetoresistance effect heads is set as the magnetoresistance effect head, and a predetermined azimuth angle is set for each of the pair of magnetoresistance effect heads; A pair of recording heads is provided as said recording head, and a predetermined azimuth angle is set for each of the pair of recording heads; When recording data on a magnetic tape, said pair of recording heads perform guard-band recording while recording data on the magnetic tape; When reproducing data from the magnetic tape, said pair of magnetoresistive effect heads reproduces data recorded by said pair of recording heads through no guard band recording; and The width of the magnetic sensor portion of the magnetoresistive effect magnetic tape is larger than the track width of one recording track recorded by the recording head by no guard band recording, and smaller than the total track width of two adjacent recording tracks . 2. A helical scan type magnetic recording/reproducing apparatus comprising: a magnetoresistive effect head fixed to a rotating drum and arranged to detect a reproduced signal from a magnetic tape on which data has been recorded converted to a chain that does not require a DC code; a high-pass filter for attenuating low-frequency components in the reproduced signal detected by the magnetoresistive head; and demodulation means for demodulating data from a reproduced signal whose low-frequency components have been attenuated by said high-pass filter before the data has been converted to a state without a DC code chain; Wherein, the magnetoresistance effect magnetic head comprises a magnetic sensor device, which detects a magnetic field from the magnetic tape, and which device is supported by a pair of magnetic shields, and Wherein, a pair of magnetoresistance effect heads is set as the magnetoresistance effect head, and a predetermined azimuth angle is set for each of the pair of magnetoresistance effect heads, a pair of recording heads is provided as said recording head, and a predetermined azimuth angle is set for each of the pair of recording heads, When recording data on a magnetic tape, the paired recording heads perform guard-band recording while recording data on the magnetic tape, and When reproducing data from the magnetic tape, the paired magnetoresistive effect heads reproduce the data recorded by the paired recording heads through the guardless band recording. 3. A helical scan type magnetic recording/reproducing apparatus comprising: a magnetoresistive effect head fixed to a rotating drum and arranged to detect a reproduced signal from a magnetic tape on which data has been recorded converted to a chain that does not require a DC code; a high-pass filter for attenuating low-frequency components in the reproduced signal detected by the magnetoresistive head; and demodulation means for demodulating data from a reproduced signal whose low-frequency components have been attenuated by said high-pass filter before the data has been converted to a state without a DC code chain; Wherein, the magnetoresistance effect magnetic head includes a magnetic sensor device and a permanent magnet, the device detects a magnetic field from a magnetic tape, and the device is a magnetoresistance effect device with a magnetoresistance effect, and the permanent magnet is arranged on the magnetic field both sides of the resistive effect device, and Wherein, a pair of magnetoresistance effect heads is set as the magnetoresistance effect head, and a predetermined azimuth angle is set for each of the pair of magnetoresistance effect heads, a pair of recording heads is provided as said recording head, and a predetermined azimuth angle is set for each of the pair of recording heads, When recording data on a magnetic tape, the paired recording heads perform guard-band recording while recording data on the magnetic tape, and When reproducing data from the magnetic tape, the paired magnetoresistive effect heads reproduce the data recorded by the paired recording heads through the guardless band recording.

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