JP2001307301A - Rotary magnetic drum device and method for measuring resistance value of magneto-resistance element head of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary magnetic drum device capable of easily and surely controlling the film thickness of a magneto-resistance element head, and a method for measuring the resistance value of the magneto-resistance element head of the same. SOLUTION: This rotary magnetic drum device 10 for reproducing the information of a tape-like information recording medium TP is provided with a fixed body 1, and a rotary body 2 having a magneto-resistance element head 20 rotated with respect to the fixed body 1 to reproduce information. The rotary body 2 is provided with a resistance value measuring section 100 for measuring the resistance value of the magneto-resistance element head 20, and a conversion section 150 for transmitting the resistance value of the magneto resistance element head 20 obtained by the resistance value measuring section 100 as data to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating magnetic drum device for reproducing information from a tape-shaped information recording medium and a method for measuring the resistance value of a magnetoresistive element head of the rotating magnetic drum device.

[0002]

2. Description of the Related Art As a device for recording information on a magnetic tape or reproducing information from a magnetic tape, there are a video tape recorder, a tape streamer and the like. Such an information recording apparatus includes a rotating magnetic drum device for recording a signal on a magnetic tape and reproducing a signal from the magnetic tape. The rotating magnetic drum device is also called a rotating magnetic head device or the like, and has a rotating drum and a fixed drum. For example, the rotating drum has a recording head and a reproducing head. The recording head is a head for recording a signal on the magnetic tape, and the reproducing head is used for reproducing a signal recorded on the magnetic tape.

The rotating drum holds the recording head and the reproducing head, and rotates the motor with respect to the fixed drum to scan the recording head or the reproducing head against the magnetic tape, for example, by a helical scan method. Thus, information can be recorded on the magnetic tape or the information on the magnetic tape can be reproduced. By employing such a helical scan method, high-density recording of signals on a magnetic tape is possible.

[0004] A magnetoresistive element head (MR head) is employed as a reproducing head of this type of rotating magnetic drum device. A reproducing magnetoresistive element head always requires a bias current to obtain a reproducing signal, and a magnetoresistive element head is a head that causes a change in resistance when a magnetic field changes, and a change in a signal magnetic field (input signal). Can be converted into a change in resistance and taken out as a change in the reproduced output signal. The magnetoresistive element head is effective as a reproducing head because it obtains a high and stable reproduced output signal without depending on the speed of the magnetic tape.

[0005] As described above, the magnetoresistive element head detects a magnetic change amount of a magnetic signal recorded on a tape-shaped information recording medium (medium) as a resistance change amount. The resistance value of the magnetoresistive element head is determined by the film thickness (M
R film thickness), and the resistance value and the film thickness are in inverse proportion. In order to optimize the resistance value of the magnetoresistive element head, it is necessary to strictly control the surface polishing amount of the magnetoresistive element head at the manufacturing stage. FIG. 11 shows a conventional grinding process for a magnetoresistive element head. The magnetoresistive element head 1000 shown in FIG.
Are manufactured by a manufacturing process of a magnetoresistive element head. As shown in FIG. 11B, the MR film 1001 of the magnetoresistive element head 1000 manufactured by the manufacturing process is polished to some extent by the abrasive 1002.

The relationship between the MR film thickness and the DC resistance value (DC resistance value) of the magnetoresistive element head 1000 is inversely proportional as shown in FIG. From this, the MR film 1001
As a measure of the amount of polishing, the MR film 1001 is polished while measuring the DC resistance value of the electrode terminal of the magnetoresistive element head. The MR film 1001, as shown by a region A in FIG.
When there is a certain thickness, the DC resistance value does not change much. However, when the film thickness becomes smaller than a certain film thickness value E, DC
The resistance value increases rapidly.

[0007]

As described above, FIG.
In the first region A, it is difficult to detect a change in the resistance value, and it is difficult to accurately control the film thickness. Therefore, in order to measure and control the film thickness, until the film thickness reaches a certain film thickness value E shown in FIG.
(B) As shown in FIG.
Grind 01. When the film thickness becomes smaller than a certain film thickness value E in FIG. 11, as shown in FIG.
, The rotating drum 1010 is mounted on an actual video tape recorder, for example. The surface of the magnetoresistive element head 1000 is polished by continuously rotating the rotating drum 1010 while the polishing tape 1020 of the cassette 1030 runs in the F direction. It absorbs the so-called variation of the magnetoresistive element head in an actual video tape recorder. By polishing with such a polishing tape 1020, the MR film thickness is further reduced, and becomes any one of the regions B in FIG.

However, such a conventional polishing method has the following problems. When the magnetoresistive element head 1000 is mounted together with the rotating drum 1010 on a video tape recorder, which is an actual machine, an operator directly measures the actual DC resistance value (also referred to as MR resistance value) of the magnetoresistive element head 1000. Cannot be used, the D of the magnetoresistive element head 1000 polished with the polishing tape 1020 is used.
Since the C resistance value is unknown, it is impossible to set an optimum resistance value at all.

Further, since the amount of polishing of the MR film 1001 of the magnetoresistive element head 1000 can be controlled only by estimating the running time of the polishing tape 1020 and the like, the so-called hit and the variation in the durability time depending on the MR film thickness are reduced. Therefore, the DC resistance value of the magnetoresistive element head is controlled, that is, the MR resistance of the magnetoresistive element head is different.
The film thickness cannot be controlled. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and provides a rotating magnetic drum device and a method for measuring the resistance value of a magnetoresistive element head of a rotating magnetic drum device, which can easily and reliably manage the thickness of a magnetoresistive element head. It is intended to be.

[0010]

According to a first aspect of the present invention, there is provided a rotary magnetic drum apparatus for reproducing information on a tape-shaped information recording medium, wherein the information is reproduced by rotating the fixed body with respect to the fixed body. A rotating body having a magnetoresistive element head for measuring the resistance of the magnetoresistive element head, wherein the rotating body measures a resistance value of the magnetoresistive element head, and the magnetic resistance obtained by the resistance value measuring section. A converter for transmitting the resistance value of the element head as data to the outside of the rotating body. In the first aspect, the rotating body has a magnetoresistive element head for rotating the fixed body to reproduce information. This rotating body has a resistance value measurement unit and a frequency conversion unit. The resistance value measuring unit measures the resistance value of the magnetoresistive element head. The conversion unit transmits the resistance value of the magnetoresistive element head obtained by the resistance value measurement unit to the outside of the rotating body as data. Thereby, the resistance value of the magnetoresistive element head can be transmitted to the outside in real time. Therefore, even if the rotating body is mounted on an actual electronic device, the magnetoresistive element head has a relation with the resistance value of the magnetoresistive element head. The thickness of the head can be accurately and easily obtained in real time.

According to a second aspect of the present invention, in the rotary magnetic drum device according to the first aspect, the resistance value of the magnetoresistive element head is a direct current resistance value, and between the rotating body and the fixed body, A non-contact transmission device for transmitting the data from the conversion unit from the rotating body to the fixed body; According to the second aspect, by using the non-contact type transmission device, the data of the resistance value of the magnetoresistive element head can be transmitted from the rotating body to the fixed body side.

According to a third aspect of the present invention, in the rotary magnetic drum device according to the second aspect, the non-contact type transmission device comprises:
A transformer for transmitting the data in a non-contact manner by magnetic induction, the transformer having a rotor core provided on the rotating body and a stator core provided on the fixed body.
According to the third aspect, the resistance value of the magnetoresistive element head can be transmitted from the rotating body to the fixed body by magnetic induction of a transformer.

According to a fourth aspect of the present invention, in the rotary magnetic drum device according to the second aspect, the non-contact type transmission device comprises:
An optical spatial transmission device that transmits the data in a non-contact manner by an optical signal, wherein the optical spatial transmission device is provided on the rotating body to generate the data, and a light emitting unit that is provided on the fixed body, from the light emitting unit. And a light receiving unit for receiving the data. According to the fourth aspect, the resistance value of the magnetoresistive element head can be transmitted from the rotating body to the fixed body in a non-contact manner by an optical signal.

According to a fifth aspect of the present invention, in the rotary magnetic drum device according to the first aspect, the resistance value of the magnetoresistive element head is transmitted as the data because the rotary magnetic drum device is mounted on an electronic device. This is performed when the magnetoresistive element head is polished in a state where the magnetic head is polished. In claim 5,
The transmission of the resistance value of the magnetoresistive element head as data is performed when the rotary magnetic drum device is mounted on an electronic device and when the magnetoresistive element head is polished. With the rotary magnetic drum device mounted on actual electronic equipment, the resistance value of the magnetoresistive element head can be calculated in real time.
That is, the value of the film thickness of the magnetoresistive element head can be accurately known while polishing.

According to a sixth aspect of the present invention, there is provided a rotating magnetic device wherein a rotating body rotates with respect to a fixed body so that a magnetoresistive element head of the rotating body reproduces information on a tape-shaped information recording medium. A measuring method for measuring a resistance value of the magnetoresistive element head in a drum device, wherein the resistance value of the magnetoresistive element head of the rotating drum is measured while the rotating magnetic drum device is mounted on an electronic device. And a data transmission step of transmitting the resistance value of the magnetoresistive element head obtained by the resistance value measurement unit as data to the outside of the rotating body. This is a method for measuring the resistance value of the magnetoresistive element head of the drum device. According to a sixth aspect of the present invention, in the measuring step, the resistance value of the magnetoresistive element head of the rotating drum is measured by the resistance value measuring unit while the rotating magnetic drum device is mounted on the electronic device. Then, in the data transmission step, the resistance value of the magnetoresistive element head obtained by the resistance value measurement unit is transmitted as data to the outside of the rotating body by the conversion unit. Thereby, the resistance value of the magnetoresistive element head can be transmitted to the outside in real time. Therefore, even if the rotating body is mounted on an actual electronic device, the magnetoresistive element head has a relation with the resistance value of the magnetoresistive element head. The thickness of the head can be accurately and easily obtained in real time.

According to a seventh aspect of the present invention, in the method for measuring a resistance value of a magnetoresistive element head of a rotary magnetic drum device according to the sixth aspect, the resistance value of the magnetoresistive element head is a DC resistance value, and And a non-contact transmission device disposed between the fixed body and the fixed body transmits the data from the rotating body side to the fixed body side. According to the seventh aspect, by using the non-contact type transmission device, the data of the resistance value of the magnetoresistive element head can be transmitted from the rotating body to the fixed body side.

According to an eighth aspect of the present invention, in the method for measuring a resistance value of a magnetoresistive element head of a rotary magnetic drum device according to the seventh aspect, the non-contact type transmission device is provided in a non-contact manner by magnetic induction. A transformer for transmitting data, wherein the transformer transmits the data in a non-contact manner by the magnetic induction between a rotor core provided on the rotating body and a stator core provided on the fixed body. According to the eighth aspect, the resistance value of the magnetoresistive element head can be transmitted from the rotating body to the fixed body by magnetic induction of a transformer.

According to a ninth aspect of the present invention, in the method for measuring the resistance value of the magnetoresistive element head of the rotary magnetic drum device according to the seventh aspect, the non-contact type transmission device transmits the data in a non-contact manner by an optical signal. A spatial light transmission device for transmitting, wherein the spatial light transmission device includes a light emitting unit that is provided on the rotating body and generates the data, and a light receiving unit that is provided on the fixed body and receives the data from the light emitting unit. The data is transmitted in a contactless manner by an optical signal. According to the ninth aspect, the resistance value of the magnetoresistive element head can be transmitted from the rotating body to the fixed body without contact by an optical signal.

According to a tenth aspect of the present invention, in the method of measuring a resistance value of the magnetoresistive element head of the rotary magnetic drum device according to the sixth aspect, the step of transmitting the resistance value of the magnetoresistive element head as the data includes This is performed when the magnetoresistive element head is polished with the rotating magnetic drum device mounted on an electronic device. According to the tenth aspect, the transmission of the resistance value of the magnetoresistive element head as data is performed when the rotary magnetic drum device is mounted on an electronic device and when the magnetoresistive element head is polished. Thus, the resistance value of the magnetoresistive element head, that is, the value of the film thickness of the magnetoresistive element head can be accurately known in real time while the rotating magnetic drum device is mounted on an actual electronic device while polishing.

According to an eleventh aspect of the present invention, in the method for measuring a resistance value of a magnetoresistive element head of a rotary magnetic drum device according to the tenth aspect, polishing the magnetoresistive element head is performed in the electronic equipment. It is a tape body for polishing. According to the eleventh aspect, the magnetoresistive element head is polished by a polishing tape that is run in the electronic device.

According to a twelfth aspect of the present invention, in the method for measuring a resistance value of a magnetoresistive element head of a rotary magnetic drum device according to the eleventh aspect, the rotation of the magnetoresistive element head is increased as the resistance value approaches a target set value. Decrease body rotation. According to the twelfth aspect, as the resistance value of the magnetoresistive element head approaches the target set value, the rotation speed of the rotating body is reduced. As a result, the polishing amount of the magnetoresistive element head can be gradually reduced, so that the resistance value can be easily set to the target set value.

According to a thirteenth aspect of the present invention, in the method of the eleventh aspect, the polishing is performed as the resistance of the magnetoresistive element head approaches a target set value. Decrease the tape tension of the tape body. According to the thirteenth aspect, the tape tension of the tape body for polishing is reduced as the resistance value approaches the target set value. As a result, the polishing amount of the magnetoresistive element head can be gradually reduced, so that the resistance value can be easily set to the target set value.

[0023]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 shows a preferred embodiment of the rotary magnetic drum device of the present invention. FIG. 2 shows an example of a sectional structure of the rotary magnetic drum device 10 of FIG. The rotating magnetic drum device 10 shown in FIGS. 1 and 2 is also called a rotating magnetic head device, a rotating magnetic reproducing device, or a rotating magnetic recording / reproducing device, and is applied to, for example, a video tape recorder, a data streamer, a digital audio system, and the like. It is used to record signals on a magnetic tape TP, which is an information recording medium, and to reproduce signals recorded on the magnetic tape TP. The rotating magnetic drum device 10 includes:
In order to reproduce a signal recorded on the magnetic tape TP, a magnetic resistance element head (MR head) 20 is provided. In addition to the magnetoresistive element head 20, a recording head for recording a signal on the magnetic tape TP is also provided, but is not shown.

The rotary magnetic drum device 10 has a fixed drum 1, a rotary drum 2, a rotary transformer 3, and a motor M. The magnetoresistive element head 20 and a recording head (not shown) are mounted on the rotating drum 2. The fixed drum 1 is a fixed body, and the rotating drum 2 is a rotating body. The rotating drum 2 is also called an upper drum, and the fixed drum 1 is also called a lower drum. The rotary transformer 3 is, for example, a power rotary transformer, and is a so-called non-contact type transmission device. As shown in FIG. 1, the magnetic tape TP enters in the tape traveling direction IN (entrance side), is guided along the lead guide portion 3 of the fixed drum 1, and then exits in the tape traveling direction OUT. It has become.

First, the fixed drum 1 will be described. FIG.
Has a main body 1A, a stator core 3A, and a cylindrical portion 30. Two sets of bearings 32 and 34 are provided in the cylindrical portion 30. A spring 36 is arranged between the bearings 32 and 34. Bearings 32, 3
The four balls 32A and 34A rotatably support the shaft 38. The spring 36 is provided between the bearings 32 and 34 because the balls 32A and 34A
By pressing the shaft 32 against the grooves 38A and 38B, the shaft 32 is rotated stably. The stator core 3 </ b> A of the rotary transformer 3 is fixed to the inner bottom surface of the fixed drum 1.

Next, the rotary drum 2 will be described. The rotary drum 2 shown in FIG. 2 has a main body 2A, a circuit board 40, a head 20, and the like. The main body 2A of the rotating drum 2 is
Like the main body 1A of the fixed drum 1, it is made of a material such as aluminum. The head 20 is a reproducing head, and one or a plurality of heads 20 are arranged at a predetermined angle with respect to the rotating drum 2. As the head 20, a reproducing head (MR head) of a magnetoresistive element type can be adopted.

The magnetoresistive element head for reproduction always needs a bias current to obtain a reproduction signal. The magnetoresistive element head is a head that causes a change in resistance when the magnetic field changes, and the signal magnetic field (input Signal) into a change in resistance and can be extracted as a change in the reproduced output signal. The magnetoresistive element head is effective as a reproducing head because it obtains a high and stable reproduced output signal without depending on the speed of the magnetic tape.

A circuit board 40 is fixed above the main body 2A of the rotating drum 2. A rotor core 3B of the rotary transformer 3 is fixed to a lower portion of the main body 2A. The rotor core 3B is arranged to face the stator core 3A with a predetermined gap. The rotating drum 2 is fixed to an upper portion of the shaft 32 by, for example, press fitting.

Next, the motor M will be described. The motor M has a rotor 70 and a stator 80. The housing 71 of the rotor 70 is held by a mounting part 72. The housing 71 has a ring shape or a disk shape, and a ring-shaped magnet 73 is fixed inside the housing 71. The magnet 73 has an S pole and an N pole alternately magnetized in multiple poles. Mounting part 72
Is fixed to the lower portion of the shaft 38 by press fitting.

The stator 80 has a stator substrate 82, a coil 84, and an iron core 86. Stator board 82
Through the coil 84 in a predetermined pattern, the rotor 70 is driven by the magnetic action of the magnet 73 for driving the rotor 70 and the coil 84 so that the rotor 70
Continuous rotation with respect to 0. The continuous rotation of the rotor 70 causes the rotary drum 2 to continuously rotate about the shaft 38 with respect to the fixed drum 1 via the shaft 38. When the rotating drum 2 rotates continuously, the recording head moves the magnetic tape TP in a helical scan manner with respect to the magnetic tape TP sent obliquely as shown in FIG.
Record information for If it is a magnetic element head, the head 20 can reproduce information recorded on the magnetic tape TP.

Next, the rotary transformer 3 shown in FIG. 2 will be described. The rotary transformer 3 is a non-contact type transmission device. As described above, the stator core 3A of the rotary transformer 3 is fixed to the fixed drum 1 side, and the rotor core 3B is fixed to the rotary drum 2 side. In the embodiment of FIG. 2, the stator core 3A and the rotor core 3B
Is a ring-shaped and disk-shaped core made of a magnetically permeable material such as ferrite. The stator core 3A and the rotor core 3B are non-contact type transformers that transmit signals by magnetic induction in a non-contact manner.

The magnetoresistive element head 20 is a magnetic tape T
The amount of change in the magnetic field of the magnetic signal, which is information recorded in P, is detected as the amount of change in resistance. D of the magnetoresistive element head
The C resistance (DC resistance) is the MR of the magnetoresistive element head.
There is a close relationship with the film thickness (magnetoresistive film thickness), that is, an inversely proportional relationship. The resistance value of this magnetoresistive element head and MR
FIG. 8 shows the relationship between the film thicknesses. In FIG.
When the film thickness is larger than, for example, 4 to 8 μm, the DC resistance value (ohms) of the magnetoresistive element head is smaller than, for example, 40 ohms and is almost constant, as shown by region A. On the other hand, in the region B where the MR film thickness is smaller than 4 to 8 μm, as the MR film thickness becomes smaller,
There is a feature that the DC resistance value of the magnetoresistive element head rapidly increases.

From the above, in order to make the resistance of the magnetoresistive element head the optimum resistance, it is necessary to strictly control the head surface polishing amount. Magnetoresistance element head (MR
The head 20 has an anisotropic magnetoresistance (AMR: Aniso)
It is a read-only head that utilizes a "tropic magnetoresistive" effect. The resistance of the magnetoresistive element head changes due to a magnetic field from a magnetic tape TP, which is a tape-shaped information recording medium. This is a structure in which a read current is extracted by passing a sense current (also referred to as a bias current) to the magnetoresistive element head. Thereby, the magnetoresistive element head 20 can obtain a high and stable reproduction output signal without depending on the speed of the magnetic tape TP.

FIG. 3 shows an example of a circuit mounted on the rotating drum 2 and an example of a circuit mounted on the fixed drum 1. The rotating drum 2 includes a bias current circuit 100 that applies a bias current to the magnetoresistive element head 20, a frequency conversion unit 150, and the like. Fixed drum 1 is amplifier 1
60 is mounted. The bias current circuit 100 of the magnetoresistive element head 20 also functions as a circuit for detecting the DC resistance value of the magnetoresistive element head 20. This corresponds to a DC resistance value resistance measurement unit.

The bias current circuit 100 and the frequency converter 150 of the magnetoresistive element head 20 are mounted on, for example, a circuit board 40 shown in FIG. Bias current circuit 10
0 is the bias current source 170 and the magnetoresistive element head 2
It has a variable resistor 175 which is an equivalent circuit of 0. The bias current is supplied to the variable resistor 175 from the bias current source 170. One end of the variable resistor 175 is a terminal 17
1 connected. The other end of the variable resistor 175 is connected to a head amplifier 180 via a capacitor 178. The other terminal 172 is connected to the head amplifier 180 via the capacitor 176. Still another terminal 173 and the above-described terminals 171 and 172 constitute a changeover switch SW1. The output side of the head amplifier 180 is connected to the winding 3M of the rotor core 3B of the rotary transformer 3.

A frequency conversion unit (corresponding to a conversion unit) 150 is provided between the terminal 173 of the changeover switch SW1 and the output side of the head amplifier 180. Terminal 173 is amplifier 1
It is connected to the V / F converter 184 via. V
The / F converter 184 converts the magnitude of the output voltage V output from the amplifier 182 into a frequency. V / F
The output side of the converter 184 is connected to the output side of the head amplifier 180, respectively. The winding 3N of the stator core 3A of the fixed drum 1 is connected to the input side of the amplifier 160. The output side of the amplifier 160 is connected to a monitor device 190 provided outside the fixed drum 1. This monitor device 190 is used by an operator to monitor the DC resistance value.

Bias current circuit 1 for magnetoresistive element head
When the bias current is sent from the bias current source 170 to the variable resistor 175, the variable resistor 175, that is, the magnetoresistive element head 20 transmits the reproduced output signal to the winding of the rotor core 3 </ b> B of the rotary transformer 3 via the head amplifier 180. Output to 3M. As a result, the reproduced output signal is transmitted to the winding 3N of the stator core 3A in a non-contact manner.
90. In this case, the terminals 171 and 172 of the changeover switch SW1 are electrically connected, and the terminal 173 is open.

On the other hand, when the bias current circuit 100 functions as a DC resistance detection circuit in order to monitor the DC resistance with the monitor 190, the changeover switch S
The terminal 171 and the terminal 173 of W1 are electrically connected, and the terminal 172 is open. In this state, the output voltage of the variable resistor 175, that is, the output voltage of the magnetoresistive element head 20, is amplified by the amplifier 182 to become the output voltage V. This output voltage V is subjected to voltage / frequency conversion by a V / F converter 184. The output frequency F obtained by the conversion is
It is supplied to the winding 3M of the rotor core 3B. Output frequency F
Is transmitted in a non-contact manner between the winding 3M of the rotor core 3B of the rotary transformer 3 and the winding 3N of the stator core 3A and sent to the amplifier 160. The amplifier 160 amplifies the transmitted output frequency F, and the output frequency F is sent to a monitor device 190 for monitoring.

Next, a method for measuring the resistance value of the magnetoresistive element head of the rotating magnetic drum device will be described. In step ST1 of the measurement step of FIG. 6, as shown in FIG. 5B, the rotating magnetic drum device 10 is mounted in a real machine, for example, a video tape recorder from the beginning of the measurement. The rotating drum 2 of the rotating magnetic drum device 10 has a magnetoresistive element head 20 mounted thereon. A polishing tape T, which is a polishing tape body, is drawn out from a polishing tape cassette C, and the polishing tape T is 2 tapes.
By being guided by the book tension guide 200,
The polishing tape T is in contact with the peripheral surface of the rotating drum 2. The polishing tape T is a tape for polishing the MR film of the magnetoresistive element head 20 of the rotating drum 2, and is, for example, a chromium oxide type (Cr ₂ O ₃ ), an iron oxide type (Fe ₂ O ₃ ) or A tape or the like containing diamond abrasive grains can be used.

Next, step ST of the measuring step of FIG.
2, the terminal 171 of the changeover switch SW1 of the frequency conversion unit 150 in FIG. 3 is electrically connected to the terminal 173. As a result, the output voltage of the variable resistor 175 corresponding to the magnetoresistive element head 20 is amplified by the amplifier 182 to become the output voltage V. The magnitude of this output voltage V is V /
The output frequency is converted to an output frequency F by an F converter 184. The output frequency F is supplied to the winding 3M of the rotor core 3B of the rotary transformer 3.

FIG. 4 shows an example of the relationship between the DC resistance value R of the magnetoresistive element head and the output voltage V and output frequency F (output frequency F for monitoring) of FIG. FIG. 4 (A)
The DC resistance value R of the magnetoresistive element head and the output voltage V have a relationship that increases substantially in the same manner as the polishing time elapses. The frequency of the output frequency F (output frequency F for monitoring) changes as shown in FIG. 4C, corresponding to the output voltage V in FIG. 4B. That is, when the value of the output voltage V is small, the frequency of the output frequency F is low,
As the output voltage V increases, the frequency of the output frequency F increases correspondingly. The output voltage V increases as the polishing time elapses, and the output frequency F also increases.

FIG. 5A shows the output frequency F for monitoring.
2 shows the relationship of the change of the frequency. When the polishing tape T shown in FIG. 5 runs in the J direction, the polishing tape T is moved with a predetermined tape tension to the magnetoresistive element head 20.
Is being polished. As shown in FIG. 8, when the MR film thickness of the magnetoresistive element head becomes smaller than, for example, 4 to 8 μm, the MR resistance value sharply increases. Amplifier 1 of FIG.
The output voltage V obtained from the magnetoresistive element head 2
As the polishing of the MR film on the head surface of No. 0 progresses, the voltage increases.

At a stage where the MR film of the magnetoresistive element head 20 is not polished much, that is, at a stage where the polishing time has not passed much, as shown in FIGS. 4B and 4C, the output voltage V is low. The output frequency F or the output frequency F for monitoring is low. However, as the MR film of the magnetoresistive element head 20 is polished and thinned,
As shown in FIGS. 4B and 4C, the output voltage V increases and the output frequency F increases.

Next, the process proceeds to the data transmission step ST3 of FIG. 6, and the change of the output frequency F of FIG. 4C is transmitted through the rotary transformer 3 of FIG.
To the fixed drum 1 side. Thereby, the operator can observe the output frequency F for monitoring by the monitor device 190.

When the output frequency F for monitoring in FIGS. 3 and 4C and the output frequency F for monitoring in FIG. 5A reach a predetermined target set value, the polishing tape shown in FIG. T
The polishing of the MR film of the magnetoresistive element head 20 using the method is ended. Thereafter, the terminal 171 of the changeover switch SW1 in FIG. 3 is electrically connected to the terminal 172 side, and the terminal 173 is opened. After this state, the rotating magnetic drum device 1
For example, a video tape recorder, which is an electronic device provided with a “0”, will be shipped.

As described above, in the embodiment of the present invention, the DC resistance value of the magnetoresistive element head is measured, and the DC resistance value R is changed from the rotating drum side to the fixed drum side through a rotary transformer which is a non-contact transmission circuit. By transmitting to
During the operation of polishing the MR film of the magnetoresistive element head 20 with the polishing tape T while rotating the rotary drum 2,
The MR film thickness of the magnetoresistive element head can be easily and reliably managed while managing the DC resistance value of the magnetoresistive element head.

FIG. 7 shows another embodiment of the method of measuring the resistance of a magnetoresistive element head according to the present invention. The embodiment of FIG. 7 is substantially the same as the embodiment of FIGS. 1 to 5 described above, but differs in the following points. The monitor device 19 of FIG.
When 0 is monitoring the output frequency F for monitoring, the value of the rotation speed SP of the rotating drum 2 and the value of the tape tension TT by the two tension guides 210 in FIG. Thus, the rotation speed S of the rotating drum 2
By changing P and the tape tension TT, it is possible to increase the polishing accuracy of the thickness of the MR film of the magnetoresistive element head.

The polishing amount and polishing time of the MR film of the magnetoresistive element head 20 greatly depend on the rotation speed SP of the rotary drum 2 and the tape tension TT, assuming that the polishing tape T is the same. The tape tension TT is a strength with which the polishing tape T is pressed against the magnetoresistive element head 20. In FIG. 7, the frequency is plotted on the vertical axis,
The horizontal axis represents the polishing time (amount of polishing), and FIG. 7 shows an example of the relationship between the output frequency F for monitoring, the tape tension TT, and the rotation speed SP of the rotary drum 2.

When the output frequency F for monitoring reaches a certain frequency Fa (Hz) during the polishing time A, the rotational speed SP of the rotary drum 2 is reduced to reduce the amount of polishing per time, thereby reducing the magnetoresistance. The amount of polishing of the MR film of the element head is accurately controlled. Further, in FIG. 7, when the output frequency F for monitoring reaches a certain frequency Fb (Hz) during the polishing time B and approaches the target thickness of the MR film, it moves in the direction X1 in which the tape tension guide 210 is weakened in FIG. This lowers the tape tension TT. Thereby, the magnetoresistive element head 20
The amount of polishing per unit time of the MR film can be accurately controlled. Then, when the polishing time C has been reached, the polishing tape T is discharged, the rotation of the rotary drum 2 is stopped, and the polishing of the MR film of the magnetoresistive element head 20 is completed. In this way, the operator observes the monitor output frequency F with the monitor device 190 in FIG.
By lowering the rotating speed SP of the rotating drum and the tape tension TT separately, the target MR differs from the conventional one even though the rotating magnetic drum device 10 is mounted on a video tape recorder which is an actual machine. The membrane can be obtained reliably and easily in real time.

Next, another embodiment of the present invention will be described with reference to FIGS. In the embodiment shown in FIG. 9, a converter 350 is provided on the rotary drum 2 side. The conversion unit 350 includes a light emitting unit 340 and an amplifier 382.
have. The output voltage 330 from the amplifier 382 is supplied to the light emitting unit 340. The light emitting unit 340 generates light intensity corresponding to the magnitude of the output voltage 330, for example, L
ED (light emitting diode) or LD (laser diode).

On the other hand, the fixed drum 1 has a light receiving section 360, an I / V converter 370, and an amplifier 380.
As the light receiving section 360, for example, a photodiode can be used. The light emitting section 340 and the light receiving section 360 constitute an optical space transmission apparatus 400 used in place of the non-contact transmission by the rotary transformer in the embodiment of FIG. When the light L generated by the light emitting unit 340 is received by the light receiving unit 360, the light receiving unit 360 generates an output current I1. The output current is subjected to current / voltage conversion by the I / V converter 370, and the output voltage V2 output from the I / V converter 370 is output.
Is amplified by the amplifier 380 to become a monitor output voltage V3 corresponding to the MR resistance value. The monitor output voltage V3 can be monitored by the monitor device 190.

In the embodiment shown in FIG. 9, the reproduction output signal of the variable resistor 175 corresponding to the magnetoresistive element head 20 is:
The power can be supplied to the winding 3M of the rotor core 3B of the rotary transformer 3 by the head amplifier 180. In this case, the terminals 171 and 172 of the changeover switch SW1 are electrically connected, and the terminal 173 is open. The output voltage of the variable resistor 175 supplied to the winding 3M of the rotor core 3B is:
The signal is sent to the winding 3N of the stator core 3A in a non-contact manner by electromagnetic induction and amplified by the amplifier 460, so that a reproduction signal of the magnetoresistive element head can be obtained. When measuring the DC resistance value of the variable resistor 175, the terminal 171 of the changeover switch SW1 is connected to the terminal 173, and the terminal 172 is opened. As a result, the voltage output from the variable resistor 175 is
The output voltage 330 is amplified by the output voltage 330, and the output voltage 330 is sent to the light emitting unit 340.

FIG. 10 shows the DC resistance value R of the magnetoresistive element head, the output voltage 330, and the light intensity 450 of the light emitting section 340.
7 shows an example of the relationship between the monitor output voltage V3 and the output voltage V3 for monitoring. These DC resistance value R, output voltage 330, light intensity 4
The relationship between 50 and the monitor output voltage V3 is such that it increases as the polishing time elapses. From this, the monitor device 190 outputs the monitor output voltage V3.
By monitoring the DC of the magnetoresistive element head.
The resistance value R, that is, the thickness of the MR film of the magnetoresistive element head can be easily and reliably checked.

In FIG. 3, D of the magnetoresistive element head is shown.
The C resistance value is converted to a frequency and transmitted in a non-contact type by electromagnetic induction. However, in the embodiment of FIG. 9, the DC resistance value of the magnetoresistive element head is transmitted not by frequency but by light by the optical space transmission device 400. In addition, it is of course possible to employ another type of non-contact transmission format instead of the optical space transmission device.

According to the present invention, the film thickness of the magnetoresistive element head of the rotary magnetic drum device can be detected by accurate measurement of the MR resistance value after mounting on the actual machine, and the reliability in the film thickness measurement is improved. Since the required minimum thickness of the MR film can be polished, the durability time due to head wear can be improved. Since the resistance value can be measured by the user after the product is shipped, the maintenance timing by the user can be estimated.

When the head surface is polished after the rotary magnetic drum device is mounted on the actual electronic equipment, the resistance value of the head can be measured in real time, so that the head can be secured against the magnetic tape and the optimum MR can be secured. The thickness can be controlled. The bias current of the MR head can be automatically adjusted by measuring the MR resistance value in a pre-shipment inspection or the like.

[0058]

As described above, according to the present invention,
The thickness of the magnetoresistive element head can be easily and reliably managed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a preferred embodiment of a rotary magnetic drum device according to the present invention.

FIG. 2 is a view showing an example of a sectional structure of the rotary magnetic drum device of FIG. 1;

FIG. 3 is a diagram showing a circuit example of a rotating drum and a fixed drum.

FIG. 4 is a diagram showing an example of a relationship among a DC resistance value, an output voltage and an output frequency of a magnetoresistive element head, and an output frequency for monitoring.

FIG. 5 is a diagram showing an example of a monitor output frequency and a state in which the surface of a magnetoresistive element head is polished with a polishing tape.

FIG. 6 is a diagram showing an example of a method for measuring the resistance value of the magnetoresistive element head of the rotating magnetic drum device of the present invention.

FIG. 7 shows an output frequency for monitor, tape tension,
FIG. 4 is a diagram showing an example of the relationship between the rotation speed of a rotating drum.

FIG. 8 is a diagram showing an example of a relationship between a DC resistance value and an MR film thickness.

FIG. 9 is a diagram showing another embodiment of the circuit example of the rotating magnetic drum device of the present invention.

FIG. 10 shows the DC of the MR head in the embodiment of FIG. 9;
FIG. 4 is a diagram illustrating an example of a relationship among a resistance value, an output voltage, light intensity of a light emitting unit, and an output voltage for monitoring.

FIG. 11 is a view showing a polishing step of a conventional magnetoresistive element head.

FIG. 12 is a diagram showing an example of a relationship between a DC resistance value and an MR film thickness.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixed drum (fixed body), 2 ... Rotary drum (rotary body), 3 ... Rotary transformer (non-contact type transmission device), 10 ... Rotary magnetic drum device, 20 ...
Magneto-resistive element head (MR head), 100: bias current circuit of the magneto-resistive element head (resistance measuring unit also serving as DC resistance detecting circuit), 150: frequency converter (converter), 175 ..Variable resistor (equivalent circuit corresponding to magnetoresistive element head 20), 210: tension guide, SP: rotation speed of rotary drum, SW1
... Changeover switch, T ... Polishing tape, TT
..Tape tension, TP ... magnetic tape (tape information recording medium)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyoshi Kurihara 1128 Shinkaicho, Hamamatsu-shi, Shizuoka Prefecture Sony Hamamatsu Co., Ltd. F-term (reference) 5D034 BA02 BB14 DA02 DA07 5D091 AA03 DD03 EE11 EE24 FF01 FF04 HH20

Claims (13)

[Claims] 1. A rotating magnetic drum device for reproducing information on a tape-shaped information recording medium, comprising: a rotating body having a fixed body, and a magnetoresistive element head for rotating the fixed body to reproduce the information. The rotating body comprises: a resistance value measuring unit that measures a resistance value of the magnetoresistive element head; and the rotating body using the resistance value of the magnetoresistive element head obtained by the resistance value measuring unit as data. And a conversion unit for transmitting the signal to the outside of the rotary magnetic drum device. 2. The resistance value of the magnetoresistive element head is a DC resistance value, and the data from the conversion unit is transmitted between the rotating body and the fixed body from the rotating body to the fixed body between the rotating body and the fixed body. 2. The rotating magnetic drum device according to claim 1, further comprising a non-contact type transmission device. 3. The non-contact transmission device is a transformer for transmitting the data in a non-contact manner by magnetic induction, wherein the transformer is a rotor core provided on the rotating body and a stator core provided on the fixed body. The rotating magnetic drum device according to claim 2, comprising: 4. The non-contact type transmission device is a spatial light transmission device for transmitting the data in a non-contact manner by an optical signal, and the spatial light transmission device is provided in the rotating body and emits light for generating the data. And a light receiving unit provided on the fixed body and receiving the data from the light emitting unit.
4. The rotary magnetic drum device according to item 1. 5. The method of transmitting the resistance value of the magnetoresistive element head as the data when polishing the magnetoresistive element head in a state where the rotary magnetic drum device is mounted on an electronic device. Item 2. The rotating magnetic drum device according to Item 1. 6. A rotating magnetic drum device wherein a rotating body rotates with respect to a fixed body so that a magnetoresistive element head of the rotating body reproduces information on a tape-shaped information recording medium. A measurement method for measuring a resistance value of a resistance element head, wherein the resistance value of the magnetoresistive element head of the rotary drum is measured by a resistance value measurement unit in a state where the rotating magnetic drum device is mounted on an electronic device. And a data transmission step of transmitting, as data, the resistance value of the magnetoresistive element head obtained by the resistance value measurement unit to the outside of the rotating body, the magnetoresistance of the rotating magnetic drum device, Element head resistance measurement method. 7. A resistance value of the magnetoresistive element head is a DC resistance value, and a non-contact transmission device disposed between the rotating body and the fixed body transmits the data from the rotating body side to the non-contact type transmission device. 7. The method for measuring a resistance value of a magnetoresistive element head of a rotary magnetic drum device according to claim 6, wherein the resistance value is transmitted to a fixed body. 8. The non-contact transmission device is a transformer for transmitting the data in a non-contact manner by magnetic induction, wherein the transformer is a rotor core provided on the rotating body and a stator core provided on the fixed body. 8. The method for measuring the resistance value of a magnetoresistive element head of a rotary magnetic drum device according to claim 7, wherein the data is sent in a non-contact manner by the magnetic induction between the magnetic heads. 9. The non-contact transmission device is an optical space transmission device for transmitting the data in a non-contact manner by an optical signal, and the light space transmission device is provided on the rotating body and emits light for generating the data. 8. The magnetoresistive element head of the rotary magnetic drum device according to claim 7, wherein the data is transmitted in a non-contact manner by an optical signal between a unit and a light receiving unit provided on the fixed body and receiving the data from the light emitting unit. 9. Resistance measurement method. 10. The method of transmitting the resistance value of the magnetoresistive element head as the data when polishing the magnetoresistive element head with the rotating magnetic drum device mounted on an electronic device. Item 7. A method for measuring a resistance value of a magnetoresistive element head of a rotary magnetic drum device according to Item 6. 11. The method for measuring a resistance value of a magnetoresistive element head of a rotary magnetic drum device according to claim 10, wherein the polishing of the magnetoresistive element head is performed by a polishing tape that is run in the electronic device. . 12. The method according to claim 11, wherein the number of revolutions of the rotating body is reduced as the resistance value of the magnetoresistive element head approaches a target set value. 13. The resistance value of the magnetoresistive element head of the rotating magnetic drum device according to claim 11, wherein the tape tension of the polishing tape body is reduced as the resistance value of the magnetoresistive element head approaches a target set value. Measuring method.