JPS6051172B2 - magnetic disk device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic disk device, particularly a magnetic disk device in which head positioning is controlled while detecting tracks by a servo head, which has a core width twice that of the servo track. The present invention relates to a magnetic disk device that uses a servo head to extract a signal with an excellent SIN ratio, and uses a simple multiplier to extract necessary signals such as cylinder pulses.

In order to position the head in a conventional magnetic disk drive, the following measures have been taken, for example. That is,
A servo with dedicated positioning signals written on the disk surface.
A track is prepared, and the servo head is positioned on a predetermined track while reading the contents of the servo track using the servo and head. As a result, the data head interlocking with the servo head is positioned on a predetermined data track. However, as the density of magnetic disk drives has increased recently, the track density in the radial direction of the disk has increased, and as a result, the track width of the data track has become narrower and narrower.

For this reason, the track width of the servo track also becomes narrower, and it becomes necessary to perform positioning using a servo and a head with a narrower core width.
Therefore, the SIN ratio of the position signal deteriorates, and the positioning accuracy deteriorates. As a method to solve this problem, Japanese Patent Laid-Open No. 53-73117 and Japanese Patent Laid-Open No. 53-73118
As shown in the publication, consideration has been given to forming a position signal by a servo head having a core width wider than the track width. The present invention develops the idea of the above-mentioned known method, and the core width of the servo head is set to 2 times the track width.
The purpose is to make it possible to extract the required signal containing the cylinder pulse by using simple multiplication means on the extracted first position signal and second position signal as a factor of 7. There is.

Therefore, the magnetic disk device of the present invention is a magnetic disk device in which data tracks and servo tracks are positioned in correspondence with each other, and the servo head performs positioning while reading the servo track.
A servo head having a core width twice the track width of the above servo track is used, and the output of the servo head generates a first position signal for identifying an even numbered track and a first position signal for identifying an odd numbered track. and a second position signal for identifying the first position signal, and the first position signal and the second position signal are switched to be used as a speed extraction signal, and the first position signal and a second position signal to extract a timing extraction signal for the switching and a cylinder pulse for detecting that the servo head intersects the servo track. It is characterized by what it did. This will be explained below with reference to the drawings. FIG. 1 is an explanatory diagram illustrating the relationship between a track and a servo head in a magnetic disk device of the present invention, and FIG. 2 is an explanatory diagram illustrating a first position signal and a second position signal obtained in the present invention. 3 shows a configuration of an embodiment of the present invention, and FIG. 4 shows a time chart for explaining the operation of the configuration shown in FIG.

In FIG. 1, 1-1, 1-2, 1-3, 1-4 are tracks, 2 is a servo head, and NS is a pattern in which servo data dedicated to positioning on the track is written and represents the state. Can be the same as the conventional pattern, T
W represents the track width, and Cw represents the core width of the head.

SDl again! It can be considered that SD2 is a pattern for identifying even-numbered tracks S2 and S4, and SD2 is a pattern for identifying odd-numbered tracks Sl and S3. As is well known, the tracks of a magnetic disk are arranged concentrically, and the magnetic disk rotates at a high speed.

In positioning the head, the head is driven in the radial direction during the above rotation. Then, the servo head 2 reads the servo data, and a position signal is extracted based on the read signal. Based on the position signal, cylinder pulses corresponding to the number of times the servo head crosses the track and a speed signal at which the servo head moves in the radial direction on the track are extracted. As shown in Figure 1, the core width CW of the servo head 2 is the track width T.
If it is twice W, the first position signal P1 is obtained corresponding to the servo data SDl that identifies the even-numbered track, and the first position signal P1 is obtained corresponding to the servo data SD2 that identifies the odd-numbered track. The second position signal P2 is a signal whose phase is shifted by π/2 as shown in FIG. In FIG. 2, E corresponds to an even track and 0 corresponds to an odd track. Point A detected in the position signal P1 is a point that identifies an even-numbered truck, and the point A detected in the position signal P1
Point B detected at is a point that identifies an odd-numbered track.

These two signals P1 and P2 do not each have a linear position signal sensitivity independently. That is, the signal P1 changes to a line/shape in the even-numbered track area E, and the signal P2 changes to a line-shape in the odd-numbered track area 0. Therefore, as a method for detecting a linear position signal while the head is moving, the above two signals P1 and P2 are switched to extract a composite signal PC as shown in FIG. It will be used as a speed detection signal when When the core width of the servo head is selected to be equal to the track width Tw as in the past, the position signal is as shown by the dotted line in FIG. 2, and when used as the speed detection signal, the second It can be considered that only the signals in the range including point-level intersections, as shown by the thick solid line in the figure, were extracted and used.

FIG. 3 shows the configuration of an embodiment of the present invention, showing the main parts for extracting the cylinder pulse CP and the speed detection signal PC.

In the figure, 3 is an analog multiplier, 4-1 and 4-2 are voltage comparators, 5-1 and 5-2 are reference voltage sources, 6 is a flip-flop, 7 is an OR circuit, and 8 is a signal switch. circuit, Pl
, P2 and PC are the signals explained with reference to FIG. 2, PM is the multiplier output, and CP is the cylinder pulse. The above-mentioned signals P1 and P2 are input to the multiplier 3, respectively.

The output of this multiplier 3 becomes a signal such as PM shown in FIG. 4, and this signal PM is compared with reference voltages +TH and -VTH in voltage comparators 4-1 and 4-2, respectively. The outputs of these comparators 1-1 and 4-2 are supplied to an OR circuit 7 to obtain a cylinder pulse CP. The output of the comparator 4-1 and the output of the comparator 4-2 are respectively supplied to a flip-flop 6, and the flip-flop 6 is turned on and off alternately as shown in the output Q shown in FIG. Then, depending on the output Q,
Controls the signal switching circuit 8. First, the illustrated signal switching circuit 8
Although a mechanical switch is shown as a representative for simplicity, it can be considered that the control is performed as follows. That is, the signal P1 is selected in the first even track area E, the inverted signal of the signal P2 is selected in the first odd track area 0,
In the second even track area E, the inverted signal of the signal P1 is selected, and in the second odd track area 0, the signal P2 is selected.
is selected, and the signal P1 is selected in the third even track area E.
Select and proceed as follows. As explained above, according to the present invention, the necessary cylinder pulse CP can be generated by simply increasing the core width of the servo head, extracting the signals P1 and P2 as position signals, and supplying them to the multiplier. This makes it possible to extract timing signals necessary for controlling the signal switching circuit 8.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating the relationship between a track and a servo head in a magnetic disk device of the present invention, and FIG. 2 is an explanatory diagram illustrating a first position signal and a second position signal obtained in the present invention. Figure 3 shows the configuration of an embodiment of the present invention.
FIG. 4 shows a time chart illustrating the operation of the configuration shown in FIG. In the figure, 1 is a track, 2 is a servo head, TW is a track width, CW is a core width, CP is a cylinder pulse, 3 is a multiplier, 4-1 and 4-2 are voltage comparators, and 6 is a flip. - A flop, 7 represents an OR circuit, and 8 represents a signal switching circuit.

Claims (1)

[Claims] 1. In a magnetic disk device in which a data track and a servo track are positioned in correspondence with each other and a servo head performs positioning while reading the servo track, a core having a width twice the track width of the servo track is used. A servo head having a width is used, and the output of the servo head extracts a first position signal identifying the even-numbered tracks and a second position signal identifying the odd-numbered tracks. configured, and the above-mentioned first
The position signal and the second position signal are switched and used as a speed extraction signal, and the first position signal and the second position signal are switched.
A timing extraction signal for the switching and a cylinder pulse for detecting that the servo head intersects the servo track are extracted using the output of the result of multiplication with the position signal. magnetic disk device.