JPH0242684A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To obtain a magnetic disk device having uniform recording/ reproducing characteristics by compensating a characteristic difference due to a head arrangement position difference between sides 0 and 1 in the double- sided magnetic disk device. CONSTITUTION:In a magnetic disk 5, since a resolution is low on an inner circumference surface in comparison with an outer circumference surface, an R/W head part 3a of a magnetic head 3 arranged at the side 0 side is always positioned at the outer circumference side by eight tracks to an R/W head part 2a of a magnetic head 2 arranged at the side 1 side, namely, at the side where the resolution is high. Consequently, the reading characteristic of the R/W head part 2a is stationarily lowered to the reading characteristic of the R/W head part 3a. Then, by utilizing a side selecting signal to select the reading side and writing side of the magnetic disk 5, when the side 0 side is designated, the reading characteristic is made lower than the case where the side 1 side is designated. Thus, the uniformity of the recording/reproducing characteristics between sides 0 and 1 both sides to accompany the arrangement positions of the R/W head parts can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic disk drive, and more particularly to a magnetic disk drive employing a so-called double-sided head.

Conventional technology In general, in order to perform double-sided recording/reproduction on a magnetic disk,
A magnetic disk device is known that includes a pair of magnetic heads and employs a so-called double-sided head.

In order to avoid crosstalk between both recording surfaces of the magnetic disk, the magnetic head in this type of magnetic disk device is configured such that the position of the read/write head section (hereinafter referred to as the R/W head section) is adjusted in the direction of movement of the head carriage. to 4~
It has a structure in which eight tracks (determined by recording density) are provided at shifted positions, and a slider made of ceramics or the like is provided on the opposite side.

5 shows the arrangement positions of the magnetic heads 2 and 3 mounted on the head carriage 1, and FIG. 6 shows the arrangement positions of the magnetic heads 2 and 3 mounted on the head carriage 1.
, 3a and sliders 2b and 3b. In each figure, d indicates the center distance of each R/W head 2°3, and 00.
01.02. ... indicates the recording track position.

In the double-sided magnetic disk drive M4 having such a configuration, the magnetic heads 2.3 disposed opposite to both disk surfaces of the magnetic disk 5 are mounted on the head carriage 1 and maintain the above-mentioned positional relationship. As it moves, it is positioned on the disc track and comes into contact with the disc recording surface. However, as the recording density increases, the difference in characteristics between the outer and inner periphery of the magnetic disk 5 due to the difference in track radius becomes significant depending on the position of the abutting tracks. It decreases as you go.

For this reason, if the filter constant of the reproducing system is adjusted to be appropriate on the tracks on the outer circumference of the magnetic disk 5, the resolution on the inner circumference will decrease and the reading margin will also decrease.

FIG. 7 shows an example of the configuration of a reading/reproducing system 6 in a conventional magnetic disk device 4. As shown in FIG. Conventionally, in order to compensate for the difference in resolution on the inner peripheral surface of the magnetic disk 5, R/W
The reproduced signal sent from the head sections 2a, (3a) is amplified by the preamplifier 7, and is then amplified by the read filter 8. Differential circuit 9.
Zero volt comparator 10. When outputting a reproduced signal through the pulse shaping circuit 11, it is common to change the constant of the read filter 8 at a constant track position near the inner circumference of the magnetic disk 5 to compensate for the characteristics. This switching is performed by automatically controlling the switch filter 8 using a signal (indicated by a dashed line in the figure) supplied from a control means (not shown).

Problems to be Solved by the Invention However, in the above conventional magnetic disk device 4, side 0
．． Since the read filters were switched at once using the same circuit for both sides, if the R/W heads 2a and 3a are installed in different positions as described above, the R/W head 2a on side 1 R/W head part 3 on side O side
It is located closer to the inner periphery than a, so if the filter constants were switched at the same position, there was a problem that complete compensation could not be achieved due to the difference in resolution.

Furthermore, countermeasures such as setting the core gap length of the magnetic head 2.3 to a range that ensures sufficient override characteristics and does not cause a peak shift may also be considered, but in this case as well, side 1.0 On the other hand, there is no difference in using the magnetic head 2.3 each time, and as mentioned above, there is an unavoidable problem that the difference in characteristics between the two occurs.

The present invention was created in view of the above points, and is based on R/
It is an object of the present invention to provide a magnetic disk device in which recording/reproducing characteristics are made uniform between both sides at 0° side depending on the arrangement position of a W head section.

Means for Solving the Problems In order to solve the above problems, the present invention provides an upper surface (side 1) and a lower surface (side 0) on both the upper and lower surfaces of the magnetic disk.
In a magnetic disk drive equipped with a pair of magnetic heads arranged several tracks apart from each other, regardless of the above-mentioned track deviation, side 0, side 0,
In order to make the read characteristics uniform on both sides of side 1,
The cut-off frequency of the low-pass filter provided in the readout circuit is switched by a side select signal that selects the movable side surface of the magnetic disk, and side 0 (IN
The reproduction frequency characteristics of the side 1 and the reproduction frequency characteristics of the side 1 are different from each other.

In addition, the resonant frequency of the differential circuit for peak detection provided in the readout circuit is switched by a side select signal that selects the movable side surface of the magnetic disk, so that the reproduction frequency characteristic on the side O side and the reproduction frequency characteristic on the side 1 side can be changed. It is also possible to have a different configuration.

In addition, the Q value of the differential circuit for peak detection provided in the readout circuit is adjusted to the side that selects the movable side surface of the magnetic disk.
A configuration may also be adopted in which the reproduction frequency characteristics on the side O side and the reproduction frequency characteristics on the side 1 side are changed by switching according to a select signal.

In addition, the write current flowing through the magnetic head during recording is switched by a side select signal that selects the movable side surface of the magnetic disk, so that the playback frequency characteristics on the side 0 side and the playback frequency characteristics on the side 1 side are different. It may also be a configuration.

Furthermore, there is no internal conflict regarding the cut-off frequency of the low-pass filter provided in the readout circuit, the resonant frequency of the differential circuit for peak detection, the Q value of the differential circuit for peak detection, or the write current applied to the magnetic head during recording. Two or more of these may be switched by a side select signal that selects the movable side surface of the magnetic disk, so that the reproduction frequency characteristics on the side O side and the reproduction frequency characteristics on the side 1 side can be made different.

As explained with reference to FIG. 6, there is a shift of several tracks (8 tracks in FIG. 6) between the recording/reproducing positions of the upper and lower magnetic heads 2 and 3, and due to this, each There is a difference in read characteristics between the outputs of the magnetic heads 2 and 3.

That is, in the magnetic disk 5, since the resolution on the inner peripheral surface is lower than that on the outer peripheral surface, the R/W head section 3a of the magnetic head 3 disposed on the side O side has a lower resolution than the magnetic head section 3a disposed on the side 1 side. Since the R/W head section 2a of the head 2 is always located 8 tracks on the outer circumferential side (on the side with higher resolution), the R/W head section 2a of the head 2
The read characteristics of the W head section 2a are steadily lower than those of the R/W head section 3a.

Therefore, by using a side select signal that selects the read side and the write side of the magnetic disk 5, when side O side is specified, the read characteristics are configured to be lower than when side 1 side is specified, and each side The structure was designed so that the readout characteristics were uniform.

Also, if the core gap length of the magnetic head 2.3 is set separately for side 0 and side 1,
The R/W head section 3a of the magnetic head 3 disposed on the side O side is the R/W head section 3a of the magnetic head 2 disposed on the side 1 side.
Although it is always located on the outer circumferential side by eight tracks with respect to the head section 2a, it constantly deteriorates with respect to the read characteristics of the R/W head section 3a.

In this case, a side select signal for selecting the read/write side of the magnetic disk 5 is used, and when side 1 is specified, the read characteristics are configured to be lower than when side 0 is specified, It may be configured so that the read characteristics on each side are uniform.

In a magnetic disk drive, the means for changing the read frequency characteristics are: (1) means for changing the cut-off frequency of the low-pass filter ■ means for changing the resonant frequency of the differential circuit 0 means for changing the resonant frequency of the differential circuit Means for changing the Q value can be considered.

Therefore, by appropriately switching among the four methods described above using a side select signal that specifies the movable side of the magnetic disk, it is possible to equalize the read characteristics at each length side.

Embodiment Next, an embodiment of the present invention will be described. FIG. 1 is a block diagram of a magnetic disk i device 12 which is an embodiment of the present invention.

In the figure, 13 is a magnetic disk, and a magnetic head 14 is on side 0 (back side), and a magnetic head 14 is on side 1 (front side).
A magnetic head 15 is disposed on each of the magnetic heads. Each of these magnetic heads 14 and 15 is designed to prevent crosstalk from occurring.
They are arranged shifted by a predetermined dimension d (eight tracks) and connected to switch 1 (hereinafter referred to as SWl). SWl is a write system 16 for each magnetic head 14.15.
It selectively supplies write signals from the magnetic heads 14 and 15, and selectively supplies read signals read by each magnetic head 14 and 15 to a reading system (described later). Also SW
l is connected to SW2.

This SW2 selectively connects each magnetic head 14, 15 to the writing system 16 or the reading system.

The writing system 16 is an old-fashioned circuit 18. Resistance RI.

It is composed of Ra and SW3. The write circuit 18 records write data on the magnetic disk 13 via the magnetic heads 14 and 15 by superimposing a write signal on the write current iw. The resistors R+ and Ra determine the value of the write current TW, and the value of the write current Jw changes depending on whether SW3 is opened or closed. The reading system is a preamplifier 19. Low pass filter 20. It is comprised of a differentiator 21, a zero-volt comparator, a pulse shaping circuit, etc. (not shown).

The preamplifier 19 amplifies minute read signals read by the magnetic heads 14 and 15.

The low-pass filter 20 switches a filter constant in accordance with the position of each magnetic head 14, 15 on the magnetic disk 13. As described above, the resolution differs between the outer circumferential surface and the inner circumferential surface of the magnetic disk 13. Therefore, for example, when the magnetic heads 14 and 15 move toward the outer circumferential surface of the magnetic disk 13, the nearer to the outer circumferential surface the higher the recording density becomes, resulting in lower resolution. Therefore, in general, when the magnetic head 14, 15 reaches a specific track, by switching the cutoff frequency of the low-pass filter 20, the track-to-track resolution can be realized regardless of the outer circumferential surface or the inner circumferential surface. There is.

This particular track is a 51/4 inch magnetic disk 13
In the case of -, the 44th track is in the shell.

Further, the switching signal for switching the cutoff frequency is configured to be supplied, for example, from the drive system of a stepping motor that drives the magnetic head 14.15, so that when the magnetic head 14 on side O reaches the 44th track, , the cutoff frequency of the low-pass filter 20 is automatically switched.

However, the cutoff frequency in the low-pass filter 2o is changed all at once, and each magnetic head 14
．． There is no switching in response to 15. That is, if the cutoff frequency when the magnetic head 14 is on the outer circumferential surface from the 44th track is A1, and the cutoff frequency when it is on the inner circumferential surface is B, then when the magnetic head 14 is on the outer circumferential surface from the 44th track, The signals from the magnetic heads 14 and 15 are both band-limited to the cutoff frequency A, and when the magnetic head 14 is located on the inner peripheral surface of the 44th track, the signals from the magnetic heads 14 and 15 are both limited to the cutoff frequency A. Bandwidth limitation of B is performed.

Therefore, with only the low-pass filter 20, the magnetic head 1
4.15 cannot be corrected due to the difference in read characteristics caused by the staggered arrangement.

The low-pass filter 20 is provided with a capacitor G+ that can vary the cutoff frequencies A and B,
The cutoff frequencies A and B change by opening and closing SW4.

A differentiator 21 is connected to the above-mentioned low-pass filter 20. This differentiator 21 includes a capacitor C2, resistors R2, Rb, coils L+, 12, and SW5 to SW7.
are provided, and the resonance frequency and Q value of the differentiator 21 can be changed by opening and closing SW5 to SW7. A zero volt controller and a pulse shaping circuit (not shown) are connected to this differentiator 21.

The magnetic disk device 12 having the above configuration is configured to open and close SW3 to SW7 as appropriate, so that each side 1.
It is possible to correct the difference in reading characteristics that occurs between the two. This will be explained below.

First, the correction accompanying the opening/closing operation of SW3 will be described.

As described above, the write current 1w can be changed by opening and closing the SW3. When SW3 is closed, the write current (W) is 1w = VCC/R+ f:t tail.

However, SW3 is closed by the side select signal,
When Ra is connected in parallel, the combined resistance becomes smaller than Ra, and the write current (W) increases. At this time, the increment of the write current vt used for the above correction is measured within the range where the override characteristic is saturated and the resolution changes. Usually, the range of change is within 1 mA, and the increase is 0.5IIAPi! Every time,
It is preferable to set the current value to about 7 to 8 mA. An example of this state is shown in FIG.

Next, the correction accompanying the opening/closing operation of SW4 will be described.

The cutoff frequencies A and B of the low-pass filter 20 can be switched by opening and opening the SW4 operated by the side select signal. When making the above correction,
Depending on the connection and disconnection of capacitor C1, the cutoff frequency is approximately 50kHz in the 2MB mode example.

FIG. 3 shows an example of this state.

Next, correction accompanying the opening operation of SW5 among SW5 to SW7 will be described. The Q value of the differentiator 21 is changed by similarly opening and closing SW5 using the side select signal, and is set to such an extent that the IF multiplied signal saddle does not cross zero on both sides 0 and 1. As mentioned above, side 0 generally has higher resolution than side 1, so by inserting resistor Rb by SW5 and connecting it in parallel with resistor R2 (however,
(R2 is a setting resistance) The combined resistance end is made small to lower the Q value. The value of the resistor Rb is generally about 50 to 100 times the resistor R2, and FIG. 4(A) shows an example of this.

Further, the resonant frequency of the differentiator 21 is changed by the configuration of SW6 or SW7, so that the characteristics of side O are lowered compared to side 1 as shown in FIG. 4<8).

As described above, by opening and closing SW3 to SW7, the difference in reading characteristics on each side 0.1 caused by the misalignment of each magnetic head 14.15 (in this example, an eight-track misalignment) is corrected. be able to. Also SW
SW3 to SW7 are operated when side 1 is designated as the side select signal, that is, when the magnetic head 15 is operated. By configuring the magnetic disk drive 12 as described above, the difference in reading characteristics due to the difference in head arrangement position on each side 0.1 is corrected, and uniform recording/reproducing characteristics can be obtained on each side 0.1. In particular, this effect is of great benefit in magnetic disk devices that perform high-density recording.

On the other hand, the above-mentioned means (1) to (4) for correcting the difference in characteristics due to the difference in the arrangement position of the magnetic heads 14, 15 do not necessarily need to be provided in the magnetic disk device 12 at the same time.

For example, when focusing on the write system 16, a resistor R that can change the value of the write current 1w in the write system 16
+, Ra and SW3 are installed, the reading system includes capacitors Ca, C2, resistor R21Rb, and coil 1.
．． There is no need to provide C2 and SW4 to SW7. This is because the writing system 16 has already performed recording correction.

Therefore, if a means for correcting the positional difference between the magnetic heads 14 and 15 is provided in the inlay system 16, the reading system may have the same configuration as the conventional one (as shown in FIG. 7). .

Further, when paying attention to the reading system, in this embodiment, means for correcting the difference in placement position of the magnetic heads 14 and 15 is provided for each of the low-pass filter 20 and the differentiator 21, but it is not necessary for both the low-pass filter 20 and the differentiator 21 to be corrected. It is not necessary to provide both the low-pass filter 20 or the differentiator 21, and even with a configuration in which only one of the low-pass filter 20 and the differentiator 21 is provided, the above correction can be sufficiently performed. In the case of this configuration, the circuit configuration of the reading system can be simplified.

Effects of the Invention As described above, according to the present invention, it is possible to compensate for the characteristic difference due to the difference in head arrangement position between sides in a double-sided magnetic disk device by 0.1, and to obtain a magnetic disk device having uniform recording/reproducing characteristics. It has the following characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic disk device that is an embodiment of the present invention, FIG. 2 is a diagram showing changes in characteristics due to closing SW3, and FIG. 3 is a diagram showing changes in characteristics due to opening SW4. Figure 4 (A>, (B) are SW5 to SW7
Figure 5 is a diagram showing the main part configuration of a magnetic disk drive, and Figure 6 explains that there is a difference in the placement position of each magnetic head on side 1 and side O. FIG. 7 is a block diagram showing a reading system of an example of a conventional magnetic disk device. 12... Magnetic disk device, 13... Magnetic disk, 14.15... Magnetic head, 16... Writing system, 17... Reading system, 18... Writing circuit, 1
9...Preamplifier, 20...Low pass filter, 2
1... Differentiator, 22... Control circuit. Figure 5 Figure 6 Figure 7 Patent applicant: TIATSUKU Co., Ltd. V-m-. Old wave number (kHz) - Kazu (A) 50kHz (kHz2C) Procedural amendments Director General of the Patent Office Ko 1) Moon Yi 1, Indication of the case 1988 Patent application No. 193288 2 Invention Name Magnetic disk device a Relationship with the person making the amendment Patent applicant address 3-7-3 Nakamachi, Musashino-shi, Tokyo 180 Name (382) TIATSUKU Co., Ltd. Representative Tani
Katsuma 4, agent address: 5-7-6 Kojimachi, Chiyoda-ku, Tokyo 102, Japan Detailed description of the invention in the specification to be amended. 7. Contents of amendment (1) Insert the following sentence between lines 5 and 6 on page 12 in the specification. `` can be considered, and if you pay attention when writing, (4) s
"Means for changing the input current value" [F] "Controller" written in lines 10 and 11 on page 16 of the same document is corrected to "comparator."

Claims (1)

[Claims] (1) On both the upper and lower sides of the magnetic disk, the upper side (side 1)
In a magnetic disk drive equipped with a pair of magnetic heads arranged several tracks apart on the lower surface (side 0), in order to make the read characteristics uniform on both side 0 and side 1, regardless of the above-mentioned track deviation. , the cut-off frequency of a low-pass filter provided in the readout circuit is switched by a side select signal that selects the movable side surface of the magnetic disk, so that the reproduction frequency characteristics on the side 0 side and the reproduction frequency characteristics on the side 1 side are changed. A magnetic disk device that is different from the above. (2) On both the upper and lower sides of the magnetic disk, the upper side (side 1)
In a magnetic disk drive equipped with a pair of magnetic heads arranged several tracks apart on the lower surface (side 0), in order to make the read characteristics uniform on both side 0 and side 1, regardless of the above-mentioned track deviation. The resonant frequency of the differential circuit for peak detection provided in the readout circuit is switched by a side select signal that selects the movable side surface of the magnetic disk, so that the reproduction frequency characteristics on the side 0 side and the reproduction frequency characteristics on the side 1 side are changed. A magnetic disk device that is different from the above. 3. In a magnetic disk drive in which a pair of magnetic heads are arranged on both the upper and lower surfaces of a magnetic disk, the upper side (side 1) and the lower side (side 0) being offset by several tracks, regardless of the above-mentioned track misalignment. In order to make the read characteristics uniform on both side 0 and side 1, the Q value of the peak detection differential circuit provided in the readout circuit is switched by a side select signal that selects the movable side of the magnetic disk. A magnetic disk device characterized in that the reproduction frequency characteristics of the side 1 and the reproduction frequency characteristics of the side 1 are different. (4) On both the top and bottom of the magnetic disk, the top side (side 1)
In a magnetic disk drive equipped with a pair of magnetic heads arranged several tracks apart on the lower surface (side 0), in order to make the read characteristics uniform on both side 0 and side 1, regardless of the above-mentioned track deviation. , The write current flowing through the magnetic head during recording is switched by a side select signal that selects the movable side surface of the magnetic disk, so that the playback frequency characteristics on the side 0 side are different from the playback frequency characteristics on the side 1 side. A magnetic disk device characterized by: (5) On both the top and bottom of the magnetic disk, the top side (side 1)
In a magnetic disk drive equipped with a pair of magnetic heads arranged several tracks apart on the lower surface (side 0), in order to make the read characteristics uniform on both side 0 and side 1, regardless of the above-mentioned track deviation. , the cut-off frequency of a low-pass filter provided in the readout circuit, the resonant frequency of the differential circuit for peak detection, the Q value of the differential circuit for peak detection, or at least two of the write current applied to the magnetic head during recording. is switched by a side select signal that selects the movable side surface of the magnetic disk, so that the reproduction frequency characteristics on the side 0 side and the reproduction frequency characteristics on the side 1 side are different. disk device.