JPS6180573A - Head positioning system - Google Patents

Abstract

PURPOSE:To attain highly accurate head positioning in a small-sized device by arranging symmetrically each servo pattern having the arrangement in the outer direction and inner direction recorded on a servo area on a center line of a data track of a positioning object. CONSTITUTION:The servo pattern on a disc consists of a pattern PA having the arrangement in the outer direction and a pattern PB having the arrangement in the inner direction crossing the data track with shifted phase. The servo head 11 detects the servo signal of the patterns PA, PB, the detected voltage is used as a position error signal by a demodulator 22, stored in a shift register 18 and stored in an RAM 31 as a bit string of the patterns PA, PB. A CPU 30 compares each bit, decides the position of the track of the head 11, a signal representing the position shift of the head 11 and the shift direction drives a step motor 28 to adjust the position of the head 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a head positioning system, and more particularly to formation of a trunk positioning signal for a movable head of a magnetic disk device having a movable head and its control system [Prior Art] In small flexible disk devices having a movable head, coarse head positioning has been performed by open-loop control using a step motor. These are 100-20
A track density of 0 TPI (racks/inch) has been achieved. This is 250 to 120 in track pitch.
It becomes μm.

[Problem that the invention seeks to solve]

However, when attempting to further increase the track density, a problem arises in that the recording medium is affected by deformation due to temperature and humidity, making it impossible to accurately position the head with respect to the tracks. For example, a medium with a polyester (polyethylene terephthalate) substrate deforms by about ±20 μm due to a change in room temperature from 0 to 30°C and humidity from 30 to 80%. Although recording capacity has been significantly increased through the development of new methods, high-precision head positioning technology that can accommodate this has not yet been realized.

Means for Solving Problems c] The present invention provides a head positioning method capable of performing highly accurate positioning for small disk devices having a movable head in view of the conventional situation as described above. In the servo signal area of a data track provided concentrically on a recording medium, a servo pattern has a servo pattern arranged in the outer direction and a servo pattern arranged in the inner direction. servo patterns, and a head that detects the signals of these servo patterns, and two types of servo signals detected by the head and obtained by selecting phases according to a predetermined combination, respectively, at a predetermined slice level.
It is characterized by comprising a means for converting into a value and a means for comparing the contents of each bit of each servo pattern corresponding to the binary output, and the position of the head with respect to the data track is known from the output of the comparing means. That is.

[Effect]

The servo patterns recorded in the servo area that are arranged in the outer direction and the servo patterns that are arranged in the inner direction are
Since the positioners are arranged symmetrically around the center line of the target data track, the head detects multiple servo signals in each of these servo patterns, levels slices the detected voltage pulses, and converts them into binary data. When comparing the bit-by-bit detection signals of both the converted servo patterns, if the head is correctly positioned on the target data track, the comparison results will match, and if the comparison result does not match, the head will be on the target data track. It is possible to recognize that the position is shifted from the original position.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a servo pattern recorded in a servo sector area of a magnetic disk using a sector servo system according to the present invention, and this servo pattern has an arrangement in the outer direction that intersects with the data track with a phase shift. Pattern PA and pattern P having an arrangement in the inner direction
It consists of B. In this figure, the vertical direction is the radial direction of the disk, the upper direction is the inner direction, the lower direction is the outer direction, and the lateral direction is the circumferential direction. Furthermore, in the outer direction arrangement, if one phase A is selected, as time passes, 80, AI, A2. A3 is an arrangement in which the magnetization pattern moves in the 7-outer direction when reading out the signal.

The servo pattern arranged in the outer direction (hereinafter referred to as the outer direction servo pattern) PA and the servo pattern in the inch direction (hereinafter referred to as the inch direction servo pattern) PB divide one trunk into M equal parts (in this example, it is divided into three equal parts). ) The servo signals are recorded at the respective positions with a phase shift. That is, the outer direction servo pattern PA has the symbol Ak(
It is composed of a plurality of servo signals (indicated by solid lines) Sl arranged sequentially in the outer direction with a shift of 173 trunk widths at the positions indicated by k・0, 1.2, . . . ) and Ck. In addition, the inch direction servo pattern PB is composed of a plurality of servo signals (indicated by dotted lines) S2 sequentially arranged in the inner direction with a deviation of i/3 track width at the positions indicated by symbols Bk and Dk on the same track. As shown in the figure, the servo signals Sl and S2 of these servo patterns are arranged so that the signals with the same positional deviation in the trunk width direction are adjacent to each other, that is, there is a gap between the servo signals S1 of the outer direction pattern PA. Inner direction pattern PB
The servo signals S2 are arranged in such a manner that the servo signals S2 are interposed therebetween. Therefore, the phase difference between the respective servo patterns must be selected to a value sufficient to allow servo signals of other types to be arranged between servo signals of the same type.

On the other hand, the data track is connected to such servo trunk Tij
They are formed on the same disk surface in the same positional relationship. Note that SH in the figure indicates a servo head.

FIGS. 2 and 3 show servo heads S located on odd-numbered servo tracks T12 and even-numbered servo tracks T22.
The detection signal waveforms for the two types of servo patterns of H are shown. Further details are shown in FIG. 2 (al is the head output waveform for the servo signal group S1 of the outer direction servo pattern PA on the servo track T12, and FIG. 2(b) is the head output waveform for the servo signal group S2 of the inner direction servo pattern PB. The waveforms are shown in FIG. 3 (Al is the head output waveform for the servo signal group S1 of the outer direction servo pattern PA of the servo track T22, and FIG. 3(b) is the head output waveform for the servo signal group S2 of the inner direction servo pattern PB. shows.

As is clear from these diagrams, the nodule S to the servo
H is the servo signal SL when passing through the servo track,
A pulse voltage is output as a detection signal at each magnetization reversal position of S2. The magnitude of this output voltage is maximum where the radial position of the servo signal coincides with the trajectory of the head, and decreases as it deviates from that position.

The head output signals in both figures show the case where the head is correctly positioned on each of the odd and even servo tracks.

After selecting such head output signals into 7 vertical direction servo patterns and 7 inch direction servo patterns using the gate signals shown in FIGS. 2(C) and 3(C), a predetermined slice level SL, e.g. By level slicing and binarizing at 50% of the maximum amplitude of the head output, a series of via columns associated with each servo pattern is obtained.

In this embodiment, as mentioned above, two types of servo signals Sl,
Since S2 is arranged at each position divided into three parts of one track, one servo pattern is arranged in seven bits in terms of the method of detecting head position deviation between two adjacent tracks. For example, the bit string of the servo signal detection pulse in FIG. 2(al) is ``1010010'' as shown in FIG. 9(d), and
The number-bo signal detection pulse has a bit string of '1010010° as shown in the same figure (Pi). Also the third
The bit string of the servo signal detection pulse in figure ta+ is shown in the same figure (
dl, and the servo signal detection pulse in FIG. 3(b) results in a bit string of "0101101" as shown in FIG. 3(e).

As is clear from comparing the bit strings of the servo patterns in the outer direction and the image direction, when the servo head SH is correctly positioned on the target track, both bit strings code bit by bit.

The attached table shows the relationship between the head position for the even-numbered track T22 shown in Fig. 4 and the bit/nod row corresponding to the henodic output. At head position 3, which is correctly positioned on track T22, all the comparison bits of the outer direction and inner direction patterns are encoded as described above. However, the other four head positions deviated from the target track T22 are 1. 2. In cases 4 and 5, mismatch results appear in the contrasting bits of the 1-inch pattern in the outer direction at different bit addresses.

Therefore, based on the result of this bit string comparison, the position of the servo to the target trunk can be accurately known. The present invention uses this as a position error signal for head position detection to perform head positioning.

FIG. 5 is a block diagram showing the configuration of the main parts for detecting the head position.
2 is a preamplifier, B is an AGC circuit 13° amplifier 14. Logic circuit 151 position position error signal 6. A demodulator includes a level sensor 17, and 18 is a shift register.

The servo head 11 positioned on a desired track detects the servo signals of the outer direction and inch direction servo patterns PA and PB at that position and outputs a pulse voltage. This output voltage is amplified by the preamplifier 12 and then
The signal is sent to an amplifier 14 and a logic circuit 15 via a circuit 13. In the logic circuit 15, the gate signal for demodulation [see FIG.
) and FIG. 3 (see dl) and this signal is sent to the position error detector 16.

The position error detector 16 also serially inputs the head output amplified by the amplifier 14, and uses the gate signal to identify and output two types of pulse signals related to the outer direction and inner direction servo patterns. do. These pulse signals are temporarily stored in the shift register 18 as a position error signal. Note that the AGC circuit 13 performs gain control based on the output of the level sensor 17.

FIG. 6 is a detailed diagram of the position error detector 16, which is comprised of a circuit 19 for sequentially selecting head outputs in accordance with gate signals, a comparator 20, and a slice level setting circuit 21. The slice level setting circuit 21 sets the slice level SL for binarization (Fig. 2+al, (
b) and FIG. 3 (see al, fbl) are set to desired values. The comparator 20 sequentially binarizes the input head output by comparing it with the slice level SL, and converts it into "1" and "0". ' is sent to the shift register 18 as a bit string. Note that +E and +E are operating power supplies.

FIG. 7 is a block diagram conceptually showing the configuration of a device for positioning a head using a position error signal which is a parallel output from the shift register 18.

In the figure, 22 is a demodulator (the part indicated by the dashed line B in FIG. 5), 23 to 25 are I10 ports, and 2
6 is a digital-analog converter (DAC), 27 is a power amplifier, 28 is a step motor, 29 is a clock generator (CLK), 30 is a central processing unit (CPU), 31
32 is a main memory consisting of a RAM, and a ROM in which a program for executing the present embodiment is written.

The position error signal, that is, the bit string of the 1 inch direction servo pattern in the outer direction, temporarily stored in the shift register 18 as described above is transferred to the RAM via the I10 port 23.
31. The CPU 30 compares these bit strings for each bit and determines the position of the head 11 with respect to the track as described above.

A signal indicating the amount and direction of positional deviation of the head 11 detected by the comparison is sent to the I10 port 24 as a control signal.
is supplied to the DAC 26 via the DAC 26, and after analog conversion, is amplified by the power amplifier 27, and is used to drive, for example, a 4-phase step motor 2.
8 and drives the motor 28 to adjust the position of the head 11. Note that the I10 port 25 is for interfacing with other external devices.

The program for executing the above operations is stored in the ROM.
32, the contents of which are shown in the flowchart of FIG. In this flowchart, the N position bits are those related to the servo signal S1 at the positions indicated by symbols Ak (k=o, 1.2...) and Ck in FIG.
Also, the Q position bits are symbols Bk and Dk in Figure 1.
This is related to the servo signal S2 at the position shown in FIG.

In this way, in this embodiment, the position of the head can be accurately detected and the positioning control can be performed with high accuracy on the target track.

In the above embodiments, the step motor 28 was used as the head moving drive means, but it is also possible to use a voice coil or a near motor.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, highly accurate head positioning can be realized for a small disk device having a movable throat.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining the present invention in detail, in which FIG. 1 is a diagram schematically showing a servo pattern, and FIGS. 2 and 3 are diagrams for odd-numbered tracks and even-numbered tracks. Head output waveform diagram for the servo pattern above,
FIG. 4 is a diagram showing the relationship between the head position and the bit string corresponding to the head output for even track T22, FIG. 5 is a block diagram showing the head position detection configuration in an embodiment of the present invention, and FIG. FIG. 7 is a block diagram showing an example of the head positioning configuration of the present invention, and FIG. 8 is a flowchart showing the head positioning control procedure of the present invention. SH and 11: Servo head, Tij: Servo trunk, PA: Servo pattern arranged in outer direction, P
B: Servo pattern arranged in inner direction, St and S2: Servo signal, Sl,; Slice level, I
2: Brianb, B and 22: fii periodizer. 13: automatic gain adjustment circuit, 14: amplifier, 15: logic circuit, 16: position error detector, 17: sensor. 18: Shift register, 19: Henodo output identification circuit. 20; comparator, 21 slice level setting circuit,
23 to 25: I10 baud I, 26: Digital-to-analog conversion W, 27: Power amplifier, 28 Step motor, 29: Chronograph generator, 30: Central processing unit, 31
: Main memory consisting of RAM, 32: Memory for storing the henodic positioning program. Attachment @ 1 Figure AO8o Co C1o A1B+ C+ O
+ Az B2 CJ Dz As BsFlex 70 Turn 7f 100 Figure 4 H Figure 2 ([ (C >+o+oo-t. -) I OI OOI
Oth 3g (d) 0 1 0 +
I OI(e) OI 0
1 + O11I Figure 5 Figure 6

Claims (1)

[Claims] A servo signal area of a data track provided concentrically on a recording medium includes a servo pattern arranged in an outer direction and a servo pattern arranged in an inner direction, each consisting of a plurality of phases arranged so as to intersect each other with respect to the track. and a head that detects the signals of these servo patterns, and two types of servo signals detected by the head and obtained by selecting phases according to a predetermined combination, respectively, and binarizing them at a predetermined slice level. means and
A head positioning method comprising: means for comparing bit-by-bit contents of each servo pattern corresponding to the binary output, and the position of the head relative to the data track is known from the output of the comparing means.