JPS61194604A - Head coil circuit - Google Patents

Abstract

PURPOSE:To eliminate a drop in an output at reading and to constitute a circuit with a minimum number of parts by providing damping resistances becoming parallel with respect to head coils at the side of a write circuit so that said resistances can act only at writing and will not act at reading. CONSTITUTION:The selection of heads HD0... is to change the biases of head coils HD0a.... And their voltages are set lower than that of a selecting circuit C, whereby diodes D1... corresponding to the head coils HD0a... act to flow a current to the specific coil, thereby selecting the head. If the current is higher than the voltage of the circuit, the coil conducts the write circuit A or a read circuit B with the aid of the actions of the diodes D9, D10, D11 and D12, and the specific head is selected at the time of writing or reading. Since the damping resistances R are provided only at the write circuit A side in parallel to respective head coils HD0a..., they will act with respect to the heads coils HD0a... only when the write circuit A is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a head coil circuit used for reading and writing in a magnetic head of a magnetic recording/reproducing device that records and reproduces information using a magnetic recording medium.

[Background of the invention]

In this type of magnetic recording/reproducing device, due to the magnetism,
The magnetic head is attached to a rotatable swing arm, and the swing arm is equipped with a mechanism to rotate in the radial direction of the magnetic disk, and the magnetic head is attached to the tip of a linear arm that can move linearly. Some devices are equipped with a mechanism for linearly moving the tip of the linear arm in the radial direction of the magnetic disk.For example, examples using a swing arm include those shown in FIGS. 4 to 10.

In the figure, l denotes a housing, and this housing 1 is approximately box-shaped, and has cooling fins 1a at the corners and an opening 2 for mounting a motor 3 for driving a magnetic disk. As shown in FIG. 6, this motor 3 uses a direct drive DC brushless type, and a rotor portion 5 in which permanent magnets 4 are housed protrudes from the lower surface of the housing 1. Reference numeral 6 denotes a bracket provided above the rotor section 5. A drive coil 7 is provided on the bottom surface of this bracket 6, and a bearing 9° for rotatably holding the drive shaft 8 is provided at the center of the bracket 6. As shown in FIG. 5, the upper surface of the bracket 6, which is fitted into the hole 2 of the housing and fixed with screws, is inserted from the position 15 facing the flange opening 14 of the drive hub 11, which will be described later. 6
A shallow groove 17 for air circulation is formed next to the circumferential surface 16 of.

11 is a drive hub fixed to the drive shaft 8 of the motor 2, and as shown in FIG. 6, this drive hub 11 has a cylindrical part 18 and a flange part 12 connected to the lower part thereof. The cylindrical portion 18 is provided with a plurality of grooves 13 on its outer peripheral surface in the axial direction.
The top surface 19 of the flange section 12 continues to the lower surface of the flange section 12 through an opening 14 provided in the flange section 12, and the upper surface of the flange section 12 is provided with a recess 20 that continues from the groove section 13 to the circumferential surface of the flange section 12. Note that the cylindrical surface 21 of the cylindrical portion 18 excluding the groove I3 and the upper surface 2 excluding the recess 20 of the flange portion 12
2 refers to the mounting surface of the bracket 6 after the drive hub 11 is attached to the drive shaft 8, which serves as a reference for positioning the magnetic disks 23° 24, and in order to rotate the magnetic disks 23° 24 without eccentricity or wobbling. High precision machining based on 25.

26 is a spacer ring, and the upper and lower surfaces of this spacer ring 26 have several recesses 27 and 27 that communicate with the inner and outer circumferences.
... is provided, and is sandwiched between two magnetic disks 23 and 24, and fitted into the cylindrical surface 21 of the drive [lambda] disk.

Reference numeral 28 denotes a cap, and this cap 28 has a substantially disk shape, and the lower surface thereof has several recesses 2 that widen toward the outer circumference.
9... are provided, and are attached to the top surface 19 of the drive hub with screws 28a..., and the magnetic disk 2
3.24 and spacer ring 26 are tightened and attached to the upper surface 22 of the flange portion of the drive hub.

In this way, the motor 3 is attached to the opening 2 of the housing 1, the drive hub 11 is attached to the drive shaft 8 of the motor 3, and the magnetic disks 23, 24 are attached to the cylindrical surface 21 of the drive hub 11.
is fitted and fixed. Thus the magnetic disk 23.2
4 can be rotated within the housing 1.

Reference numeral 30 denotes a cylindrical annular wall 30 provided along the outer periphery of the magnetic disks 23 and 24 of the housing 1;
The wall surface 3 of the housing l is located at the counterclockwise end 31 of the housing l.
A rectifying plate 33 is provided substantially parallel to 2. An air filter 34 is fixed to the housing between the rectifying plate 33 and the wall surface 32 of the housing l. This air filter 34 has an air inlet (not shown) opened between the wall surface 32 of the housing 1 and the rectifying plate 33, and the bottom surface 3 of the housing 1.
The case 39 has an air outlet 37 open to the air circulation groove 36 of 5, has a dust collection efficiency of 99.97% or more for dust with a particle size of 0.3 μm, and is made of porous material or laminated paper 38.
It is stored in. The air circulation groove 36 of the housing continues to the groove part 17 of the motor bracket, and is covered by a groove cover 40.

41 is an arm shaft 4 fixed to the housing 1;
On the side wall 45, which is rotatably attached around 2,
A stepping motor 46 fixed to the housing l
Both ends of a steel belt 49, the middle part of which is wound around a pulley 48 fixed to a drive shaft 47, are fixed at both ends. That is, one end 49a of the steel belt 49 is attached with a bolt 87a through a washer 85, and the other end 49b is attached with a bolt 87b through a washer 86 near both ends of the steel belt attachment part 45 of the swing arm 41. There is. Further, a plate spring 53 is provided on the other end side 49b of the steel belt 49, and a bent portion 5 of the steel belt attachment portion 45 of the swing arm 41 is provided with a leaf spring 53.
5, the steel belt 49 is connected to the tangential plane of the curved surface of the swing arm mounting portion 45! The steel belt 49 is ejected in this direction. This temporary spring 53 is screwed onto the swing arm 41 by the bolt 87b with one end 53b inserted inside the steel belt 49. This shows the starting point of contact between the bent portion 53a of the concave portion 55 and the steel belt 49 for clearing, and this point X is the tangent plane! It is located above.

60... is a total of four magnetic heads provided corresponding to each of the front and back surfaces of the two magnetic disks 23 and 24,
Each of the magnetic heads 60 is composed of a core slider 61, a flexure 62, a load finker 63, and a mount 64, and the cylindrical portion 65 of the mount 64 is inserted into the star-shaped hole 67 of the head substrate 66 to create a magnetic field. head 60・
... are fixed to the head substrate 66..., and the head substrate 66... is fixed to the swing arm 4I.

Then, a front side Fi 71 is attached to the side surface of the housing 1 in which the motor 2 equipped with the magnetic disks 23, 24, the swing arm 41, the stepping motor 46, etc. are attached, a cover 72 is attached to the top surface, and each backing 73 is attached as shown in FIG.
．． 74 to form an airtight chamber 75. The cover 72 is provided with a respirator 76, and the air inside and outside the airtight chamber 75 comes into contact only through this respirator 76, and this respirator 76 also has a resistance of 99.97% or more against dust with a particle size of 0.3 μm. is a frame, and this frame 77 is attached to the lower surface of the housing 1 via anti-vibration rubber feet 78.
Screw holes 79 are provided to protect the rotor portion of the motor 2 and to be used when mounting the present magnetic disk device in a computer (not shown) or the like. 80.81
is an electric circuit board 80.81, which is attached to the lower surface of the housing 1 and protected by the frame 77 as shown in FIG. Electric circuit board 8
A ground plate 82 is fixed on the magnetic disk 23.
It is in contact with a sphere 83 provided at the lower end of the drive shaft 8 of the motor 2 in order to release static electricity generated at 24 degrees.

Next, the operation of the magnetic disk device will be explained.

When a current of a predetermined voltage is applied to the magnetic disk device, the drive shaft 8 of the motor 3 rotates counterclockwise, and with this rotation, the drive hub 1 fixed to the drive shaft 8 rotates, causing the drive hub 11 to rotate. Fixed magnetic disks 23, 24 rotate. When the magnetic disks 23 and 24 rotate, the air near the surface of the magnetic disk rotates due to the frictional force with the surface of the magnetic disk, and is subjected to centrifugal force due to this rotation. Therefore, the air near the magnetic disk is as shown by the arrow in Figure 5.
It is discharged toward the outer circumference while rotating counterclockwise. A part of this air is directly discharged to the outside of the magnetic disks 23 and 24, but since the annular wall 30 of the housing l blocks the air, air with increased pressure near the annular wall 30 hits the annular wall 30. The air flows counterclockwise along the line, is blown out at once from the terminal end 31 of the annular wall, is guided by the rectifying plate 33, and flows into the air filter 34. The air filter 34 sends clean air from which dust has been removed to the air circulation groove 3 of the housing 1.
Discharge at 6. The clean air discharged from the air filter 34 passes through the air circulation groove 36 of the housing l and flows out into the groove 17 of the motor bracket. Although this groove 17 is not covered, the air flowing between the bracket 6 and the magnetic disk 23 is decelerated by the frictional force with the bracket 6, so it does not affect the flow of clean air in the groove 17. , this clean air can flow to the lower part 15 of the opening 14 provided in the flange portion 12 of the drive hub 11 . As mentioned above, the air near the surface of the magnetic disk is discharged to the outside of the magnetic disk 23, 24 by centrifugal force.
Near the inner periphery of the magnetic disks 23 and 24 and the drive hub 11
Since the air inside the groove 13 is under negative pressure, the clean air that has flowed up to the lower part 15 of the opening 14 in the flange flows into the groove 13 of the drive hub 11 and further flows into the flange of the drive hub. 12 recesses 20 . . . , spacer ring 26 recesses 27 . . . and cap 20 recesses 29 .

In this way, the air discharged by centrifugal force due to the rotation of the magnetic disks 23 and 24 is purified by the air filter 34,
The air is supplied to the front and back surfaces of the isks 23 and 24 via the air circulation groove 36 of the housing and the groove 17 of the bracket 16 of the motor 12.

On the other hand, the magnetic head 60... applies approximately 10 g to the front and back surfaces of the magnetic disk 23.24 when the magnetic disk 23.24 is stationary.
However, when the magnetic disks 23 and 24 rotate as described above and the air on the front and back surfaces of the magnetic disks 23 and 24 begins to rotate together, the magnetic head 60
Air flows between the magnetic disks 23 and 24, and the magnetic heads 60 float. This magnetic head 6
Since the flying height of 0... is about 0.6 μm, dust with a particle size smaller than this will pass between the magnetic head 60... and the magnetic disk 23,24, but dust with a particle size of 0.6 μm or more will pass between the magnetic head 60... and the magnetic disk 23.24. Particle-sized dust is caused by the magnetic head 60... and the magnetic disk 23.
．． 24 and collides with the magnetic head 60.
...or damage the magnetic disks 23, 24 or both, so please use the air filter 33 to prevent damage to 0°3 μm.
Removes dust particles with a particle size of

When the magnetic disks 23, 24 rotate in this way and the magnetic heads 60... float up, the drive shaft 47 of the stepping motor 4G is rotated at a predetermined angle to wind up the tensioning pulley 48, and the other end is loosened and released from the pulley 48. By unwinding, the swing arm 41 rotates, and the magnetic head 60 attached to the swing arm is positioned on a track at a predetermined radial position of the magnetic disk 23, 24.
Record and play back information.

Incidentally, in a magnetic disk device constructed and operated as described above, a head coil circuit as shown in the circuit diagram of FIG. 11 has conventionally been used. The figure shows four read/write heads HDO, HD1. HD2. HD
3, each head has head coils HDOa, HD1a, HD2a, ID3
a and each head coil HDOa, HD1a, ID2a
.

Damping resistor I (DOb, HDl) parallel to ID3a
b, ID2b, ID3b, each head coil HD
Oa to ID3a are connected in parallel to write circuit A and read circuit B, and each head HDO to ID3 is selectively used for writing and reading, respectively.

In this head coil circuit, the damping resistor HD
Ob through ID3b are provided in parallel with head coils HDOa through ID3a, respectively, and these damping resistors HDOb through ID3b act during both writing and reading. Damping resistance HDOb
ID3b and ID3b are necessary to prevent and smooth the write pulse from becoming steep especially during writing, but are not necessary during reading, and conversely cause a decrease in the output from the head coil HDOa or ID3a. Ta.

Therefore, in the head coil circuit shown in FIG. 11, a damping resistor HDOb is inserted in parallel with each head coil HDOa, which causes a decrease in output during reading. At the same time, there was a problem that the number of parts was large and the cost was high.

[Purpose of the invention]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and has an object to provide a head coil circuit for a magnetic head that can be constructed from small parts.

[Summary of the invention]

To achieve the above object, the present invention provides a plurality of magnetic heads, each of which is selectively used for writing or reading, and a head coil of each magnetic head is connected to a writing circuit and a reading circuit. In the head coil circuit connected in parallel to the circuit, a damping resistor is provided in parallel to each of the head coils on the write circuit side, and this damping resistor acts only during writing, and acts only during reading. It is characterized in that the read characteristics are improved without deteriorating the write characteristics.

[Embodiments of the invention]

Hereinafter, a head coil circuit according to an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a circuit diagram of a head coil circuit according to an embodiment of the present invention, and FIG. 2 is a waveform diagram showing write waveforms when this head coil circuit is used without providing a damping resistor. In the following description, the same components as those in the prior art example described above are designated by the same reference numerals.

In FIG. 1, the head coil circuit includes each magnetic head H.
DO, HDI, HD2. Head coils HDOa and HD1a are respectively provided in HD3.

HD2a, HD3a, diodes D to D8 provided in each of the head coils HDOa to HD3a, diodes D* and D+o provided in the read circuit B side of the head amplifier, and the write circuit A side of the head amplifier. , a damping resistor R that is parallel to each of the head coils HDOR to HD3a, and a damping resistor R provided to each of the head coils HDOR to H.
It consists of a selection circuit C for selecting D3a.

Each head HDO to HD3 has two magnetic disks 2.
3.24, respectively, and the head coils HDOa to HD3a are respectively provided in parallel. Each diode D1 is connected to each head coil H in a direction that allows conduction to the head coil HDOa... side with respect to the head coil HDOa name 1 to HD3a.
They are provided in the conductor wires DOa, respectively.

The selection circuit C is loaded with a voltage of 12V for 6 seconds, but is lowered to a predetermined voltage by a resistor Rc, enabling head selection of each of the head coils HDOa to HD3a.

Diodes Dq and D+ are provided in read circuit B and write circuit A of the head amplifier, respectively. ,D.

D I g is for selecting either read circuit B or write circuit A.

Head HDO... is selected by head coil HDOa.
By changing the bias of..., this head coil HDOa.
By making the voltage of ... lower than the voltage of selection circuit C, the diode DI ... corresponding to the head coil HDOa ... acts, and a current passes through the specific head coil HDOa. , the voltage of either write circuit A or read circuit B is selected by selection circuit C.
and diodes D,,D, if higher than the voltage of the circuit formed by a particular Herad coil. ,D, ,D
,! Due to the action of , conduction is established with either write circuit A or read circuit B, and a specific head is selected for writing or reading. In a head coil circuit equipped with such a selection system, since the damping resistor R is provided in parallel with each head coil HDOa only on the write circuit A side, the write circuit A is selected. Otherwise, the damping resistance R is equal to each head coil HDOa...
When reading circuit B is selected, the resistance does not act at all and the output does not decrease during reading.

That is, when write circuit A is selected, head coil HDOa provided in parallel to each head coil
Writing to the magnetic disk is performed with a damping effect on only one of the HDs 3a. A waveform diagram when a signal is input via the damping resistor R at this time is shown in FIG. Further, FIG. 3 shows a waveform diagram under the same conditions when the damping resistor R is not provided in the circuit.

From FIGS. 2 and 3, it can be clearly seen that the input signal is smoothed when the damping resistor R is provided. As the write waveform, a pulse of 400 na is used for one cycle, and the pulse heights LaI and l required for writing are
, at, and the pulse heights lal and Lag are added with extra rising parts Lb1 and Lbt at the time of rising, but it is desirable that these extra rising parts Lb and L b t are as small as possible, in the actual machine. is l, ag and Lb! It is necessary that the ratio of la + to L b + be 10% or less, preferably 5% or less. However, in the case of FIG. 3 without damping resistance R, Lb, is approximately 50 of Lag
%, and in the case of FIG. 2 with a damping resistance R, L b + is in the range of 5% to 6.5% of La. Therefore, it can be seen that sufficient write characteristics can be obtained by simply providing one damping resistor R in the write circuit A of the head coil circuit in parallel with each head coil.

Note that in this case, since the reading circuit B is not provided with any resistance that reduces the output, the output does not decrease.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in a head coil circuit of a magnetic head that writes information to and reads information from a magnetic recording medium, a damping resistor is provided only on the writing circuit side of each coil of the magnetic head. Since it is installed in parallel with the damping resistor, only one damping resistor is required, reducing the number of parts and reducing costs.

■ Since only one damping resistor is required, it is possible to reduce assembly man-hours and reduce costs.

(2) Since this damping resistance does not act at all on the read side, the read characteristics are improved compared to the conventional one.

There are other effects.

[Brief explanation of the drawing]

1 and 2 are for explaining the head coil circuit of the present invention, and FIG. 1 is a circuit diagram of the head coil circuit,
Figure 2 is a waveform diagram of the measured input waveform input to the head coil, Figure 3 is a waveform diagram of the measured input waveform input to the head coil when no damping resistor is provided, and Figure 4 is a waveform diagram of the measured input waveform input to the head coil.
Figures 1 to 10 are for explaining a conventionally used magnetic disk device, in which FIG. 4 is a perspective view showing the external appearance of the magnetic disk device, FIG. 5 is a sectional view, and FIG. 6 is a cover. Fig. 7 is a perspective view showing the internal configuration; Fig. 8 is a partially sectional perspective view showing the drive unit; Fig. 9 is an exploded perspective view showing the drive unit; Fig. 10 is a swing FIG. 11 is a plan view of the main part showing the arm section, and a circuit diagram showing a conventional head coil circuit. A...Write circuit, B...Read circuit, C...Selection circuit, HDO, HDI, HD2. HD3...Head, H
DOa, HDla, HD2a, HD3a --- Head coil, pasted, Dt, D3. Da, Ds, DA, Dt. D@, D drop 5 Dl. , Dz, Dt mushroom...diode, R... damping resistance. ): Figure 1 Figure 2 Figure 9 Figure 4 Figure 10 Figure 1/Figure C /2V

Claims (1)

[Claims] A plurality of magnetic heads are provided, each of which is selectively used for writing or reading, and each head coil is connected in parallel to a write circuit and a read circuit, and the head coil is connected to the write circuit side in parallel. A head coil circuit characterized in that a damping resistor is provided in parallel with each of the head coils.