JP4151196B2 - Rotating magnetic head device and method for measuring resistance value of magnetoresistive element head of rotating magnetic head device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotating magnetism for reproducing information on a tape-like information recording medium. head Equipment and rotating magnetism head The present invention relates to a method of measuring a resistance value of a magnetoresistive element head of an apparatus.
[0002]
[Prior art]
Devices that record information on a magnetic tape or reproduce information on a magnetic tape include a video tape recorder and a tape streamer. This type of information recording apparatus includes a rotating magnetic drum device for recording a signal on a magnetic tape and reproducing a signal on the magnetic tape.
The rotating magnetic drum device is also called a rotating magnetic head device, 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 a magnetic tape, and the reproducing head is used for reproducing a signal recorded on the magnetic tape.
[0003]
The rotating drum holds the recording head and the reproducing head, and rotates by rotating the motor with respect to the fixed drum, so that the recording head or the reproducing head is scanned with respect to the magnetic tape by, for example, a helical scan method. Information can be recorded on the tape and information on the magnetic tape can be reproduced. By adopting 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 apparatus.
A magnetoresistive element head for reproduction always requires a bias current to obtain a reproduction signal, and a magnetoresistive element head is a head that causes a change in resistance when the magnetic field changes, and changes in the signal magnetic field (input signal) Can be converted into a resistance change and extracted as a change in the reproduction output signal. The magnetoresistive element head is effective as a reproducing head because it obtains a high and stable reproducing output signal without depending on the speed of the magnetic tape.
[0005]
As described above, the magnetoresistive element head detects the amount of magnetic change of the magnetic signal recorded on the tape-shaped information recording medium (medium) as the amount of resistance change. The resistance value of the magnetoresistive element head is closely related to the film thickness (also referred to as MR film thickness) of the magnetoresistive element head, and the resistance value and the film thickness are inversely related.
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 polishing process of a magnetoresistive element head. A magnetoresistive element head 1000 shown in FIG. 11A is manufactured by a magnetoresistive element head manufacturing process. In the magnetoresistive element head 1000 manufactured by the manufacturing process as described above, the MR film 1001 is polished to some extent by the polishing material 1002 as shown in FIG.
[0006]
The relationship between the MR film thickness of the magnetoresistive element head 1000 and the DC resistance value (DC resistance value) is inversely proportional as shown in FIG. Therefore, the MR film 1001 is polished while measuring the DC resistance value of the electrode terminal of the magnetoresistive element head as a measure of the amount of polishing of the MR film 1001. As shown in region A of FIG. 12, the MR film 1001 does not change much in DC resistance when it has a certain thickness. However, when the thickness is smaller than a certain film thickness value E, the DC resistance value increases rapidly.
[0007]
[Problems to be solved by the invention]
From the above, figure 12 In region A, it is difficult to detect a change in resistance value, and it is difficult to accurately manage the film thickness. Therefore, in order to be able to measure and manage the film thickness, 12 Until the film thickness value E shown in FIG. 11 As shown in (b), the MR film 1001 is polished using an abrasive 1002. Figure shows film thickness 12 When the film thickness is smaller than a certain film thickness value E, 11 As shown in (c), after the magnetoresistive element head 1000 is attached to the rotating drum 1010, 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 is traveling in the F direction. The so-called variation of the magnetoresistive element head in an actual video tape recorder is absorbed. By such polishing with the polishing tape 1020, the MR film thickness is further reduced. 12 The film thickness is any one of the region B.
[0008]
However, such a conventional polishing method has the following problems. When the magnetoresistive element head 1000 is mounted on a video tape recorder as an actual machine together with the rotating drum 1010, the operator directly measures the actual DC resistance value (also referred to as MR resistance value) of the magnetoresistive element head 1000. Therefore, the DC resistance value of the magnetoresistive element head 1000 polished with the polishing tape 1020 is unknown, and cannot be set to an optimum resistance value at all.
[0009]
In addition, since the polishing amount of the MR film 1001 of the magnetoresistive element head 1000 can be managed only by estimation based on the running time of the polishing tape 1020 and the like, variation in durability time depending on the so-called hit and MR film thickness is mounted. Since it differs for each actual machine, management of the DC resistance value of the magnetoresistive element head, that is, management of the MR film thickness of the magnetoresistive element head cannot be performed. Accordingly, the present invention solves the above-described problems, and the rotating magnetism capable of easily and reliably managing the film thickness of the magnetoresistive element head. head Equipment and rotating magnetism head It is an object of the present invention to provide a method for measuring a resistance value of a magnetoresistive element head of an apparatus.
[0014]
[Means for Solving the Problems]
The present invention of Rotating magnetism head The device is a rotating magnet that reproduces information on a tape-shaped information recording medium. head An apparatus comprising: a fixed body; and a rotating body having a magnetoresistive element head for reproducing the information by rotating with respect to the fixed body, the rotating body having a resistance of the magnetoresistive element head A resistance value measuring unit for measuring the value, and a conversion unit for transmitting the resistance value of the magnetoresistive element head obtained by the resistance value measuring unit as data to the outside of the rotating body. Shi The resistance value of this magnetoresistive element head In the manufacturing stage of the magnetoresistive element head, This rotating magnet head The magnetoresistive element head is polished while the device is mounted on an electronic device. And manage the amount of polishing When Transmit as data Is.
In the present invention, the resistance value of the magnetoresistive element head is In the manufacturing stage of the magnetoresistive element head, Rotating magnetism head Polishing the magnetoresistive element head while the device is mounted on an electronic device And manage the amount of polishing When Transmit as data . This allows rotating magnetism head With the apparatus mounted on an actual electronic device, the resistance value of the magnetoresistive element head, that is, the film thickness value of the magnetoresistive element head can be accurately known in real time.
[0019]
The present invention of Rotating magnetism head The method of measuring the resistance value of the magnetoresistive element head of the apparatus is such that the rotating body rotates relative to the fixed body, and the magnetoresistive element head of the rotating body is a tape-shaped information recording medium. of Rotating magnetism that is designed to reproduce information head apparatus In This is a measuring method for measuring the resistance value of the magnetoresistive element head. head With the device mounted on an electronic device, this rotation body A measuring step for measuring the resistance value of the magnetoresistive element head by the resistance value measuring unit, and data for transmitting the resistance value of the magnetoresistive element head obtained by the resistance value measuring unit to the outside of the rotating body as data Transmission step Shi The resistance value of this magnetoresistive element head In the manufacturing stage of the magnetoresistive element head, This rotating magnet head The magnetoresistive element head is polished while the device is mounted on an electronic device. And manage the amount of polishing When Transmit as data Is.
In the present invention, the resistance value of the magnetoresistive element head is In the manufacturing stage of the magnetoresistive element head, Rotating magnetism head Polishing the magnetoresistive element head while the device is mounted on an electronic device And manage the amount of polishing When Transmit as data . This allows rotating magnetism head With the apparatus mounted on an actual electronic device, the resistance value of the magnetoresistive element head, that is, the film thickness value of the magnetoresistive element head can be accurately known in real time.
[0020]
The invention according to claim 3 is the rotating magnetism according to claim 2. head In the method of measuring the resistance value of the magnetoresistive element head of the apparatus, the magnetoresistive element head is polished by a polishing tape body that is run in the electronic apparatus. According to the third aspect of the present invention, the magnetoresistive element head is polished by a polishing tape body that is run in an electronic apparatus.
[0021]
The invention of claim 4 provides the rotating magnetism according to claim 3. head In the method of measuring the resistance value of the magnetoresistive element head of the apparatus, the rotational speed of the rotating body is lowered as the resistance value of the magnetoresistive element head approaches a target set value. According to a fourth aspect of the present invention, the rotational speed of the rotating body is decreased as the resistance value of the magnetoresistive element head approaches the target set value. As a result, the amount of polishing of the magnetoresistive element head can be gradually reduced, so that the resistance value can be easily set to the target set value.
[0022]
The invention according to claim 5 is the rotating magnetism according to claim 3. head In the method of measuring the resistance value of the magnetoresistive element head of the apparatus, the tape tension of the polishing tape body is lowered as the resistance value of the magnetoresistive element head approaches a target set value. According to the fifth aspect, the tape tension of the polishing tape body is lowered as the resistance value approaches the target set value. Thus, the amount of polishing of the magnetoresistive element head can be gradually reduced, so that the resistance value can be easily set to the target set value.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.
[0024]
FIG. 1 shows the rotating magnetism of the present invention. head apparatus (Hereinafter referred to as a rotating magnetic drum device) The preferred embodiment of is shown. FIG. 2 shows an example of a cross-sectional structure of the rotating magnetic drum device 10 of FIG. The rotating magnetic drum device 10 of 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, etc. Is used for recording a signal on a magnetic tape TP, which is an information recording medium, and reproducing a signal recorded on the magnetic tape TP. The rotating magnetic drum device 10 has a magnetoresistive element head (MR head) 20 in order to reproduce a signal recorded on the magnetic tape TP. In addition to the magnetoresistive element head 20, a recording head for recording signals on the magnetic tape TP and the like are provided, but the illustration is omitted.
[0025]
The rotating magnetic drum device 10 includes a fixed drum 1, a rotating 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 rotary 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 a power rotary transformer, for example, and is a so-called non-contact type transmission device. As shown in FIG. 1, the magnetic tape TP enters from the tape traveling direction IN (inlet side), is guided along the lead guide portion 3 of the fixed drum 1, and then exits along the tape traveling direction OUT. It has become.
[0026]
First, the fixed drum 1 will be described. The fixed drum 1 shown in FIG. 2 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 disposed between the bearings 32 and 34. Balls 32A and 34A of the bearings 32 and 34 support the shaft 38 in a rotatable manner. The spring 36 is provided between the bearings 32 and 34 by pressing the balls 32A and 34A against the grooves 38A and 38B of the shaft 38. 38 Is to stably rotate. A stator core 3 </ b> A of the rotary transformer 3 is fixed to the inner bottom surface of the fixed drum 1.
[0027]
Next, the rotating drum 2 will be described.
The rotating drum 2 shown in FIG. 2 has a main body 2A, a circuit board 40, a head 20, and the like.
Similar to the main body 1A of the fixed drum 1, the main body 2A of the rotating drum 2 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 magnetoresistive element type reproducing head (MR head) can be adopted.
[0028]
This reproducing magnetoresistive element head always requires a bias current when a reproduction signal is obtained, and the magnetoresistive element head is a head that causes a change in resistance when the magnetic field changes. The change can be converted into a resistance change and extracted as a change in the reproduction output signal. The magnetoresistive element head is effective as a reproducing head because it obtains a high and stable reproducing output signal without depending on the speed of the magnetic tape.
[0029]
A circuit board 40 is fixed to the upper part of the main body 2 </ b> A of the rotary drum 2. A rotor core 3B of the rotary transformer 3 is fixed to the lower part of the main body 2A. The rotor core 3B is disposed to face the stator core 3A with a predetermined gap.
The rotary drum 2 is fixed to the upper part of the shaft 32 by, for example, press-fitting.
[0030]
Next, the motor M will be described. The motor M has a rotor 70 and a stator 80. A housing 71 of the rotor 70 is held by a mounting portion 72. The housing 71 is ring-shaped or disc-shaped, and a ring-shaped magnet 73 is fixed inside the housing 71. The magnet 73 is obtained by alternately magnetizing S poles and N poles. The mounting portion 72 is fixed to the lower portion of the shaft 38 by press fitting.
[0031]
The stator 80 has a stator substrate 82, a coil 84, and an iron core 86.
By energizing the coil 84 in a predetermined pattern through the stator substrate 82, the rotor 70 continuously rotates with respect to the stator 80 by the magnetic action of the magnet 73 for driving the rotor 70 and the coil 84. When the rotor 70 is continuously rotated, the rotating drum 2 is continuously rotated about the shaft 38 with respect to the fixed drum 1 via the shaft 38.
When the rotary drum 2 rotates continuously, the recording head records information on the magnetic tape TP by a helical scan method with respect to the magnetic tape TP that is fed obliquely as shown in FIG. If it is a magnetic element head, the head 20 can reproduce the information recorded on the magnetic tape TP.
[0032]
Next, the rotary transformer 3 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 rotating drum 2 side. In the embodiment of FIG. 2, the stator core 3A and the rotor core 3B are ring-shaped and disk-shaped cores, and are 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 non-contact magnetic induction.
[0033]
The magnetoresistive element head 20 detects a magnetic field change amount of a magnetic signal, which is information recorded on the magnetic tape TP, as a resistance change amount. The DC resistance value (DC resistance value) of the magnetoresistive element head is closely related to the MR film thickness (magnetoresistive film thickness) of the magnetoresistive element head, that is, inversely proportional. The relationship between the resistance value of the magnetoresistive element head and the MR film thickness is shown in FIG. In FIG. 8, when the MR film thickness is larger than 4 to 8 μm, for example, the DC resistance value (ohms) of the magnetoresistive element head is smaller than 40 ohms, for example, as shown by region A, and is almost constant. .
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 is reduced, the DC resistance value of the magnetoresistive element head is rapidly increased.
[0034]
For this reason, to make the resistance value of the magnetoresistive element head an optimum resistance value, it is necessary to strictly control the head surface polishing amount.
The magnetoresistive element head (MR head) 20 is a read-only head that utilizes an anisotropic magnetoresistive (AMR) effect. The resistance of the magnetoresistive element head changes due to the magnetic field from the magnetic tape TP which is a tape-shaped information recording medium. In this structure, a reproduction voltage is extracted by flowing a sense current (also referred to as a bias current) to the magnetoresistive element head. As a result, the magnetoresistive element head 20 can obtain a high and stable reproduction output signal without depending on the speed of the magnetic tape TP.
[0035]
FIG. 3 shows a circuit example mounted on the rotating drum 2 and a circuit example mounted on the fixed drum 1.
The rotary drum 2 is equipped with a bias current circuit 100 that applies a bias current to the magnetoresistive element head 20, a frequency conversion unit 150, and the like. The fixed drum 1 is equipped with an amplifier 160.
The bias current circuit 100 of the magnetoresistive element head 20 also serves as a DC resistance value detection circuit of the magnetoresistive element head 20. It corresponds to a resistance value measuring unit for DC resistance value.
[0036]
The bias current circuit 100 and the frequency converter 150 of the magnetoresistive element head 20 are mounted on, for example, the circuit board 40 shown in FIG. The bias current circuit 100 includes a bias current source 170 and a variable resistor 175 that is an equivalent circuit of the magnetoresistive element head 20. The variable resistor 175 is supplied with a bias current from the bias current source 170. One end of the variable resistor 175 is connected to the terminal 171. The other end of the variable resistor 175 is connected to the head amplifier 180 via a capacitor 178. Another terminal 172 is connected to the head amplifier 180 via a capacitor 176. Further, 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.
[0037]
A frequency converter (corresponding to a converter) 150 is provided between the terminal 173 of the changeover switch SW1 and the output side of the head amplifier 180. The terminal 173 is connected to the V / F converter 184 via the amplifier 182. The V / F converter 184 converts the magnitude of the output voltage V output from the amplifier 182 into a frequency.
The output side of the V / F 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 a device for the operator to monitor the DC resistance value.
[0038]
When a bias current is sent from the bias current source 170 of the bias current circuit 100 of the magnetoresistive element head to the variable resistor 175, the variable resistor 175, that is, the magnetoresistive element head 20 rotates the reproduction output signal via the head amplifier 180. Output to the winding 3M of the rotor core 3B of the transformer 3. As a result, the reproduction output signal is transmitted to the winding 3N of the stator core 3A in a non-contact manner, so that the amplifier 160 can send the reproduction output signal to the monitor device 190. In this case, the terminal 171 and the terminal 172 of the changeover switch SW1 are electrically connected, and the terminal 173 is in an open state.
[0039]
On the other hand, when the bias current circuit 100 functions as a DC resistance value detection circuit in order to monitor the DC resistance value with the monitoring device 190, the terminal 171 and the terminal 173 of the changeover switch SW1 are electrically connected, and the terminal 172 Is in an open state. In this state, the output voltage of the variable resistor 175, that is, the magnetoresistive element head 20 is amplified by the amplifier 182 to become the output voltage V. This output voltage V is voltage / frequency converted by a V / F converter 184.
The output frequency F obtained by the conversion is supplied to the winding 3M of the rotor core 3B. The 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 output frequency F that has been sent, and this output frequency F is sent to the monitor device 190 for monitoring.
[0040]
Next, a method for measuring the resistance value of the magnetoresistive element head of the rotating magnetic drum apparatus will be described.
In step ST1 of the measurement step of FIG. 6, as shown in FIG. 5 (B), the rotating magnetic drum device 10 is incorporated and mounted on a real machine such as a video tape recorder from the beginning of the measurement. A magnetoresistive element head 20 is mounted on the rotating drum 2 of the rotating magnetic drum device 10. The polishing tape T, which is a polishing tape body, is fed out from the cassette C for polishing tape, and the polishing tape T is guided by the two tension guides 200 so that the polishing tape T is polished. T is in contact with the peripheral surface of the rotating drum 2. This polishing tape T is a tape for polishing the MR film of the magnetoresistive element head 20 of the rotary drum 2, and is made of, for example, chromium oxide (Cr ₂ O _Three ), Iron oxide (Fe ₂ O _Three Or a tape containing diamond abrasive grains can be used.
[0041]
Next, in step ST <b> 2 of the measurement step in FIG. 6, the terminal 171 of the changeover switch SW <b> 1 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 the output voltage V is converted to an output frequency F by the V / F converter 184. The output frequency F is supplied to the winding 3M of the rotor core 3B of the rotary transformer 3.
[0042]
FIG. 4 shows a relationship example between the DC resistance value R of the magnetoresistive element head and the output voltage V and output frequency F (monitoring output frequency F) of FIG.
The DC resistance value R of the magnetoresistive element head shown in FIG. 4A and the output voltage V have a relationship that increases in substantially the same manner as the polishing time elapses. Corresponding to the output voltage V of FIG. 4B, the frequency of the output frequency F (monitoring output frequency F) changes as shown in FIG. 4C. That is, when the value of the output voltage V is small, the frequency of the output frequency F is low. However, when 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.
[0043]
FIG. 5A shows the relationship between changes in the output frequency F for monitoring.
As the polishing tape T in FIG. 5 travels in the J direction, the polishing tape T polishes the MR film of the magnetoresistive element head 20 with a predetermined tape tension. As shown in FIG. 8, when the MR film thickness of the magnetoresistive element head becomes smaller than, for example, 4 to 8 [mu] m, the MR resistance value rapidly increases. The output voltage V obtained from the amplifier 182 in FIG. 3 increases as the MR film on the head surface of the magnetoresistive element head 20 is polished.
[0044]
In the stage where the MR film of the magnetoresistive element head 20 is not polished much, that is, the stage where the polishing time has not passed so much, as shown in FIGS. 4B and 4C, the output voltage V is low and the output frequency F is low. Alternatively, the output frequency F for monitoring is low.
However, as the MR film of the magnetoresistive element head 20 is polished and thinned, the output voltage V increases and the output frequency F increases as shown in FIGS. 4B and 4C.
[0045]
Next, the process proceeds to a data transmission step ST3 in FIG. 6, and such a change in the output frequency F in FIG. 4C is transmitted from the rotary drum 2 to the fixed drum 1 side in a non-contact manner through the rotary transformer 3 in FIG. To do. As a result, the operator can observe the monitor output frequency F with the monitor device 190.
[0046]
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 T shown in FIG. 5 is used. The polishing of the MR film of the magnetoresistive element head 20 was completed.
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, for example, a video tape recorder, which is an electronic device including the rotating magnetic drum device 10, is shipped.
[0047]
Thus, 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 transmitted from the rotary drum side to the fixed drum side through the rotary transformer which is a non-contact transmission circuit. Thus, during the operation of polishing the MR film of the magnetoresistive element head 20 with the tape T for polishing while rotating the rotary drum 2, the MR film of the magnetoresistive element head is managed while managing the DC resistance value of the magnetoresistive element head. Thickness can be easily and reliably managed.
[0048]
FIG. 7 shows another embodiment of the method of measuring the resistance value 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. While the monitor device 190 of FIG. 3 is monitoring the monitoring output frequency F, the value of the rotational speed SP of the rotary drum 2 of FIG. 5 and the value of the tape tension TT by the two tension guides 210 are changed. . Thus, by changing the rotational speed SP of the rotating drum 2 and the tape tension TT, it is possible to increase the polishing accuracy of the MR film thickness of the magnetoresistive element head.
[0049]
The polishing amount and the polishing time of the MR film of the magnetoresistive element head 20 greatly depend on the rotational speed SP of the rotating drum 2 and the tape tension TT if 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 head 20.
In FIG. 7, the vertical axis represents frequency and the horizontal axis represents polishing time (polishing amount). In FIG. 7, an example of the relationship between the output frequency F for monitoring, the tape tension TT, and the rotational speed SP of the rotating drum 2. Is shown.
[0050]
When the output frequency F for monitoring reaches a certain frequency Fa (Hz) at the polishing time A, the rotational speed SP of the rotary drum 2 is slowed down to reduce the polishing amount per hour, thereby reducing the magnetoresistive element head. Accurate control of the amount of polishing of the MR film.
Further, in FIG. 7, when the output frequency F for monitoring reaches a certain frequency Fb (Hz) at 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. As a result, the tape tension TT is lowered. As a result, the amount of polishing per hour of the MR film of the magnetoresistive element head 20 can be accurately controlled.
When the polishing time C is 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 can lower the rotational speed SP of the rotating drum and the tape tension TT separately while observing the monitor output frequency F with the monitor device 190 of FIG. Despite the fact that the apparatus 10 is mounted on a video tape recorder which is an actual machine, a target MR film can be obtained reliably and easily in real time, unlike the conventional case.
[0051]
Next, another embodiment of the present invention will be described with reference to FIGS. In the embodiment of FIG. 9, a conversion unit 350 is provided on the rotating drum 2 side. The conversion unit 350 includes a light emitting unit 340 and an amplifier 382. The output voltage 330 from the amplifier 382 is supplied to the light emitting unit 340. The light emitting unit 340 is, for example, an LED (light emitting diode) or an LD (laser diode) that generates light intensity corresponding to the magnitude of the output voltage 330.
[0052]
On the other hand, the fixed drum 1 includes a light receiving unit 360, an I / V converter 370, and an amplifier 380. For the light receiving unit 360, for example, a photodiode can be used.
The light emitting unit 340 and the light receiving unit 360 constitute an optical space transmission device 400 that is 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 amplified by the amplifier 380 and is used for monitoring corresponding to the MR resistance value. The output voltage V3 becomes the output voltage V3, and the monitor output voltage V3 can be monitored by the monitor device 190.
[0053]
In the embodiment of FIG. 9, the reproduction output signal of the variable resistor 175 corresponding to the magnetoresistive element head 20 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 terminal 171 and the terminal 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 sent to the winding 3N of the stator core 3A in a non-contact manner by electromagnetic induction, and is amplified by the amplifier 460, whereby 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 amplified by the amplifier 382 to become the output voltage 330, and this output voltage 330 is sent to the light emitting unit 340.
[0054]
FIG. 10 shows a relationship example between the DC resistance value R of the magnetoresistive element head, the output voltage 330, the light intensity 450 of the light emitting unit 340, and the monitor output voltage V3.
The relationship between the DC resistance value R, the output voltage 330, the light intensity 450, and the monitor output voltage V3 is a relationship that increases as the polishing time elapses.
From this, the monitoring device 190 can easily and reliably check the DC resistance value R of the magnetoresistive element head, that is, the thickness of the MR film of the magnetoresistive element head, by monitoring the output voltage V3 for monitoring. it can.
[0055]
In FIG. 3, the DC resistance value of the magnetoresistive element head is converted into a frequency and transmitted in a non-contact manner 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 other types of contactless transmission formats instead of the optical space transmission device.
[0056]
In the present invention, the film thickness of the magnetoresistive element head of the rotating magnetic drum apparatus can be detected by accurate measurement of the MR resistance value after mounting on the actual machine, and the reliability in film thickness measurement is improved.
Since the minimum necessary polishing of the MR film thickness is possible, 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.
[0057]
When the head surface is polished after mounting the rotating magnetic drum device in an actual electronic device, the head resistance value can be measured in real time, so that the head can be secured against the magnetic tape, and the optimum MR film thickness can be obtained. Can be managed. The MR head bias current can also be automatically adjusted by measuring the MR resistance value during inspection prior to product shipment.
[0058]
【The invention's effect】
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 rotating magnetic drum device of the present invention.
2 is a diagram showing an example of a cross-sectional structure of the rotating magnetic drum device of FIG.
FIG. 3 is a diagram illustrating an example of a circuit in a rotating drum and a fixed drum.
FIG. 4 is a diagram showing an example of the relationship between the DC resistance value, output voltage and output frequency of a magnetoresistive element head, and output frequency for monitoring.
FIG. 5 is a diagram showing an example of how the surface of the magnetoresistive element head is polished with the output frequency for monitoring and the tape for polishing.
FIG. 6 is a diagram showing an example of a method for measuring a resistance value of a magnetoresistive element head of the rotating magnetic drum apparatus of the present invention.
FIG. 7 is a diagram illustrating an example of a relationship between a monitor output frequency, a tape tension, and a rotational speed of a rotating drum.
FIG. 8 is a diagram showing an example of the relationship between the DC resistance value and the MR film thickness.
FIG. 9 is a diagram showing another embodiment of a circuit example of the rotating magnetic drum device of the present invention.
10 is a diagram showing an example of the relationship between the DC resistance value of the MR head, the output voltage, the light intensity of the light emitting section, and the output voltage for monitoring in the embodiment of FIG. 9;
FIG. 11 is a diagram showing a polishing process of a conventional magnetoresistive element head.
FIG. 12 is a diagram showing an example of the relationship between the DC resistance value and the 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 ... Magnetoresistive element head (MR head), 100... Bias current circuit of magnetoresistive element head (resistance value measuring unit also serving as a DC resistance detection circuit), 150... Frequency converting unit (converting unit), 175. ..Variable resistors (equivalent circuit corresponding to magnetoresistive element head 20), 210 ... tension guide, SP ... rotational speed of rotating drum, SW1 ... changeover switch, T ... polishing tape TT ... tape tension TP ... magnetic tape (tape-shaped information recording medium)

Claims (5)

A rotary magnetic head device for reproducing information on a tape-shaped information recording medium,
A fixed body, and a rotating body having a magnetoresistive element head for reproducing the information by rotating with respect to the fixed body,
The rotating body transmits a resistance value measuring unit that measures a resistance value of the magnetoresistive element head, and a resistance value of the magnetoresistive element head obtained by the resistance value measuring unit as data to the outside of the rotating body. have a, a conversion unit for,
The resistance value of the magnetoresistive element head is controlled by polishing the magnetoresistive element head in the manufacturing stage of the magnetoresistive element head and with the rotary magnetic head device mounted on an electronic device. Rotating magnetic head device that transmits as data . By rotating body rotates relative to the fixed body, the magnetoresistive element head of the rotating body in the rotary magnetic head device adapted to reproduce the information of the tape-like information recording medium, the magnetoresistive element head It is a measuring method to measure the resistance value,
A measurement step of measuring a resistance value of the magnetoresistive element head of the rotating body with a resistance value measuring unit in a state where the rotating magnetic head device is mounted on an electronic device, and the magnetism obtained by the resistance value measuring unit a data transmission step of transmitting to the outside of the rotating body the resistance value of the element head as data, was closed,
The resistance value of the magnetoresistive element head is controlled by polishing the magnetoresistive element head in the manufacturing stage of the magnetoresistive element head and with the rotary magnetic head device mounted on an electronic device. A method of measuring a resistance value of a magnetoresistive element head of a rotary magnetic head device that transmits data as data . Wherein for polishing a magnetoresistive element head, magnetic resistance measuring method of the resistance element head according to claim 2 is a tape body for polishing that is running in the electronic apparatus. Magnetoresistive measuring method of the resistance element head according to claim 3 to reduce the rotational speed of the rotating body as the resistance value of the magnetoresistive element head approaches the target setpoint. Magnetoresistive measuring method of the resistance element head according to claim 3 to reduce the tape tension of the tape body for the abrasive as the resistance value of the magnetoresistive element head approaches the target setpoint.

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