JPH01241069A - Disk device - Google Patents

Abstract

PURPOSE:To position a head at high speed for a data track even in case of a disk having no servoinformation by providing on the disk external part the position sensor which can obtain the positional signal of a head in plural phases continuously and can obtain at the same repeating period as that of a servoinformation pattern or at the period of the integral times thereof. CONSTITUTION:The title disk device is a flexible disk device using a voice coil motor 4 for a positioning mechanism and a position detecting sensor 5 is provided at the carriage 3 part of a disk 1 external part so as to obtain the position of a head from the other excepting the disk 1 as well. In case of using the subordinate disk having no servoinformation for a position following control circuit 9 the continuous positional signals transmitted from the external part position sensor are transmitted and the following control to the position of the above of the position sensor corresponding to the aiming track located on the disk is performed. In case of using the disk on which the servoinformation is formed, the discrete positional signal fed from the disk is transmitted and a following control is executed on the aiming track. The head positioning of high speed and high accuracy is thus enabled.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention provides a data track that targets a head according to servo information previously formed in a part of a sector provided on a disk. The present invention relates to a disk device for positioning.

(Prior art) Conventionally, in many flexible disk devices that allow disk replacement and disk devices that have several disks, in order to increase track density, formatting efficiency is high, there is no thermal off-track, and high precision is achieved. A sector servo system that allows positioning is used.

In this sector servo method, as shown in FIG. 4(b), a servo information pattern that repeats at a predetermined period is formed in advance in a part of the sector, that is, the servo sector 24, from the inner circumference to the outer circumference, and the number of sectors and the disk The servo information pattern is read by the head for each sector at a sampling period determined by the rotational speed of the head, and the head is caused to follow the target track in accordance with one or more phase position signals obtained from the servo information pattern.

Generally speaking, disk devices that use a voice coil motor that can perform high-speed, high-precision head positioning in disks that use the sector servo system.

The head is positioned to the target track by speed control to move the head at high speed to near the target track and track following control to accurately follow the data track. For example, servo pattern A26. shown in FIG. 4(b). B27. From C28 and B29.

X (=A-B) in FIG. 4(a)13. Y(=CD
) 14 is obtained, and in track following control, the head follows the data track by controlling so that A-B or CD becomes zero, that is, X and Y become zero. . Also in speed control.

The moving speed of the head is controlled so that the head moves at high speed to near the target track according to a preset speed table, but the head speed is determined from the positions of two consecutive sectors. If the head positions obtained in the sector are PPa and PPb, the head velocity V is given by V = PPb - PPa.

The absolute position of the head on the disk, that is, the distance PP from the reference position, is determined by the zone signal 25 in FIG. Group U (=X+Y)2
2,1 = As is clear from FIG. 4, the section LO where the head exists is determined by determining the magnitude of X and Y.

LL, L2. L3 can be determined, and furthermore, the positions Do, DI, D2. D3
is obtained as follows by using U and V.

DO=V/a+0.5: LO D1=0.5-υ/a: LI D2=0.5-V/a: L2 D3=U/a+o, 5: L3 Here, a is as shown in Fig. 4 (a ) are the amplitude values of X and Y shown in FIG. Thus, in the case of the 4-track cycle servo information pattern shown in FIG. 4(b), if the head movement distance is less than 4 tracks in one sector time, the absolute position 1dPPb determined by the previous sector and the current The current absolute position PPa is determined from the section La in which the head is located and the position Da within the section.

(Problem to be Solved by the Invention) In this way, in a disk device that uses a sector servo method as a positioning method and a voice coil motor as a positioning mechanism, such as a high-speed, large-capacity flexible disk device, the disk must have servo information written in advance. , the head cannot be positioned on the data track. Therefore, in a lower disk having no servo information and a lower track density, the head cannot be positioned on the data track, and the data on that disk cannot be read at all.

In addition, in a disk device that uses only the conventional sector servo method, position information cannot be obtained from one sector to the next, so if the head goes off-track due to disturbance etc. during data writing, one There is no problem as long as the amount of off-tracking within the sector period does not reach the adjacent track, but if the amount of off-tracking within that period is so large that it reaches the adjacent track, erase the data on the adjacent track. This becomes a problem.

Furthermore, in the sector servo system, control is performed using a small amount of information intermittently for each sector, so if a sector cannot be detected even once due to a disk defect, etc., this can be a problem. If a sector cannot be detected, head position information cannot be obtained and the position cannot be determined. Conventionally, if the next sector cannot be detected within a certain period of time from the previous sector, it is treated as a detection error and the position control signal is not sent. At the same time as setting it to zero, writing was prohibited and data writing was interrupted there. however,
If the distance traveled by the head during two sector periods is less than four tracks, the absolute position of the head can also be determined when the sector following the undetected sector is detected. However, in this case as well, if a sector becomes undetectable during speed control, the speed is increasing, so even if position information can be detected in the next sector, it may no longer be possible to determine the absolute position.

Furthermore, in magnetic disk drives and the like, the track width of the head is generally set smaller than the track pitch so that data on adjacent tracks will not be erased even if slightly off-track. However, in the sector servo method, the data R/W (read/write) head also reads position information, so the position signal group actually obtained is as shown in Figure 5, and the position signal linearity within the track is Bad, especially 30 in the figure
The absolute position detection accuracy is the worst in the part. However, the portion 30 in the figure is a position 0.5 track away from the center of the data track, and is the position at which speed control is switched to track following control. If this position is inaccurate, control after entering track following control may not be successful.

The present invention was made in consideration of such information, and
It is possible to position the head on the data track even if the disk does not have servo information, and for sector servo type disks, high precision can be achieved without increasing the servo information on the disk, that is, without causing any decrease in format efficiency. An object of the present invention is to provide a disk device that can reliably detect the position of the head, is resistant to external disturbances, and can perform high-speed, high-precision head positioning. Servo information for positioning the head is formed from the inner circumference to the outer circumference in some servo sectors of the sectors provided on the disk at a predetermined period, and the sampling periphery is determined by the number of sectors and the rotation speed of the disk. This servo information is read out by the head for each servo sector,
In a disk device that positions the head to a target track according to the multi-phase position signals obtained by this, the position signals for head positioning are obtained continuously and in multiple phases, and the repetition period is the same as that of the servo information or an integral multiple thereof. A position sensor that can be obtained from the cycle is provided outside the disk, and when a disk without servo information is used, the position signal obtained from this position sensor is used to position the head to the target track, and the servo information is preformed. For a disk, the head position on the disk is determined from the servo information obtained from the servo sectors of the disk at each sampling period, and the head position on the disk obtained from each servo sector and the head position on the position sensor are calculated in advance. The amount of relative position deviation is determined for each sector during one rotation of the disk, and the position of the head on the disk is corrected or interpolated using this amount of relative position deviation and the position of the head on the position sensor to position the head to the target track. This is a disk device characterized by the following.

(Function) A position sensor is provided outside the disk, which can obtain a continuous head position signal in a plurality of phases, and can obtain it at the same repetition period as the servo information pattern or at an integral multiple thereof;
When a disk without servo information is used, the position signal obtained from the external position sensor is used to position the head to the target track. The absolute position is determined from the position signal obtained at the sector position of the disk at each sampling period, and the amount of relative position deviation between the absolute position of the head on the disk obtained in advance from each servo sector and the absolute position of the head on the external position sensor is calculated. is determined in terms of sector positions during one rotation of the disk, and this relative position deviation and the absolute position of the head on the external position sensor are used to correct or separate the absolute position of the head on the disk and position it to the target track. , Even for disks without servo information, it is possible to position the head on the data track at high speed, and since position signals similar to those from the disk can be obtained, it is possible to perform head positioning using position signals only from the disk. The control program for positioning control can be used as is, and there is almost no increase in the amount of the program.

Furthermore, since more accurate and continuous positional information can be obtained for sector servo type disks, the position can be immediately detected even if the disk goes off track due to disturbances, etc., and the data on the adjacent track will not be erased. In addition, even if a sector cannot be detected due to a disk defect or the like and position information cannot be obtained, accurate position can be obtained. Furthermore, by replacing positional information with poor linearity between tracks with positional information from an external position sensor, accurate absolute positions of the heads on the disk can be obtained.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a block configuration of a disk device according to an embodiment of the present invention. The disk device is a flexible disk device that uses a voice coil motor (VCM) 4 as a positioning mechanism, and a position detection sensor 5 is provided on the carriage 3 outside the disk 1 so that the head position can be obtained from sources other than the disk 1. It is being Among the position signals created by the position signal detection circuits 6 and 7 in the figure, the position signal from the disk is a discrete signal that is sampled in each sector and held at the 0th order, and is A/D converted at the sampling period of each sector. The signal is analog-to-digital converted by the device 11 and taken into the μCPU 8. Further, the position signal from the external position sensor 5 is a continuous signal, and the A/
It can be converted into D and taken into the μCPU. μCPU
II calculates the absolute head position and head speed, which will be explained below, from the captured position signal. When using a lower disk without servo information, the position tracking control circuit 9 receives continuous position signals from an external position sensor, and performs tracking to the position on the position sensor corresponding to the target track on the disk. Control takes place. Furthermore, when a disk on which servo information is formed is used, discrete position signals are sent from the disk, and tracking control is performed to a target track. In speed control, a speed control signal is generated in the μCPU for both the lower disk without servo information and the disk on which servo information is formed, depending on the difference from the target speed table. This speed control signal is then sent to the current amplifier 10 via the D/A converter 12 to perform speed control.

Position signal X13 obtained from the disk in (a) of Fig. 2
．． Position signal LX15.Y14 obtained from the external position sensor (b). The position signal obtained from the disk, which indicates LY16 and also indicates their positional relationship, is a two-phase signal with a four-track period, which is the same as in the conventional example.

The position signal obtained from the position sensor provided outside the disk has a period of 2 times the period of the position signal obtained from the disk.
It is a phase signal. Here, since the flexible disk causes a large eccentricity due to expansion and contraction due to temperature and humidity and its replacement, in reality, the position signal from the disk with respect to the position signal from the external position sensor causes a DC offset and a deviation due to the eccentricity. It appears to move in a sinusoidal manner across the width.

Now, when using a lower disk that does not have servo information for head positioning, the head is positioned at a position on the external position sensor that corresponds to the target track using continuous position signals from the external position sensor. As in the case of the conventional sector servo system, by determining the magnitude of the position signals LX and LM from the external position sensor as shown in FIG. 2, the sections LLO, LLI, and
LL2. LL3 can be determined, and the positions LDO, LDI, LD2. L
D3 is determined by (a) or (b) shown below, and the absolute position of the head on the external position sensor is obtained.

C) LDO=2XLX/b: LLOLDI=
b/2-X: LLILD2 =-2X LX/b
: LL2LD3= b /2+LX : LL3(
b) LDO=b/2-LY: LLOLDI=
-2X LY/b: LLILD2=b/2+LY
: LL2 LD3=2XLY/b : LL3 b is LX15. This is the amplitude value of LY16.

Here, the track density of the lower disk with no servo information is 17 times higher than that of the upper disk with servo information.
16, so that the center of the data track of the lower disk is located at the position where the position signal obtained from the external position sensor becomes zero, and furthermore, as shown in FIG.
Track 001 of the lower disk is placed at the second zero cross point.
The external position sensor is attached so that 7 is located.

Furthermore, if the interval between the points where the position signal crosses zero is counted as one track, as in the prior art, the data tracks of the lower disk are located every eight tracks in this case.

According to the position obtained from the external position sensor as described above, the head is moved at high speed by controlling the speed until it approaches the position on the external position sensor corresponding to the target track, and the head is moved 0.5 track from the target position. If the target position is reached, position follow-up control for controlling the head is switched so that the position signal becomes zero, and positioning is performed at the target position. Since the position signal obtained from the external position sensor is continuous, a wide servo band can be obtained and a stable positioning servo system can be realized. Furthermore, since it is a continuous signal, the sampling period of the position signal can be set arbitrarily.

In order to treat the same speed unit and share software with the upper disk where servo information is formed, that is, to make the number of tracks moved per sampling period the same, the sampling period must be set to 2 on the upper disk. Just double it. However, if the number of samplings is increased, the position can be detected even at higher speeds, so speed control becomes possible and high-speed seek can be realized.

Next, the case of using a disk on which servo information is formed will be explained.

In this case, the absolute position of the head on the external position sensor corresponds to the position of the head on the disk, with the interval between the points where the position signal crosses zero being two tracks. When positioning the head of a disk on which servo information is formed, the relative position deviation amount between the absolute position of the head on the external position sensor and the absolute position of the head on the disk is determined in advance.As mentioned above, this is due to the eccentricity of the disk. Therefore, the position signal from the disk is D relative to the position signal from the external position sensor.
This is because a C offset is generated and the swing width of the disk changes due to eccentricity. Note that this relative position deviation amount is within ±2 tracks. First, the head is positioned at the transformer 900 position on the external position sensor using the external position sensor. At this time, the position signal obtained from each sector of the disk over one revolution of the disk becomes a signal as shown at 18 in FIG. This indicates the relative positional deviation between the absolute position of the head on the external position sensor and the absolute position of the head on the disk. However, 19 or 20 in Fig.
There may also be cases where this signal falls into the nonlinear region of the position signal, as in the case of . Therefore, a DC offset signal is added to the position signal from the external position sensor, and the head is moved until all the fluctuations in the position signal due to eccentricity fall within the linear region of the position signal. For example, as shown in Figure 2, if the oscillation part of the position signal from the external position sensor is b, this corresponds to 4 tracks, and in order to offset by d tracks (= real number), it is necessary to offset by 4xd/b. Do it by adding or subtracting. Furthermore, since this position signal has the best linearity near the O level, the center of the variation in the position signal due to eccentricity is set near the O level, as shown at 21 in FIG. This can be done by making sure that the sum of the maximum and minimum values of the fluctuations in the position signal due to eccentricity is 0, and the absolute position LPP of the head on the external position sensor at this time, on the disk in each servo sector. If the absolute position of the head is PP, then PP
The value obtained by subtracting this LPP from the value is stored in memory as the relative position deviation amount.

Therefore, when positioning the head, each time a servo sector arrives, the absolute position of the head on the disk and the absolute position of the head on the position sensor are determined, and the absolute position of the head on the position sensor is determined by the amount of relative position deviation determined in advance. is used to convert to the absolute position of the head on the disk. Then, compare the absolute position of the head on the disk obtained directly from the disk with the absolute position obtained by the conversion, and if it is 0
．． If there is a difference of two or more tracks, the absolute position of the head directly obtained from the disk is considered to be incorrect, and the absolute position obtained by conversion is used instead.

In addition, if the signal cannot be read and the servo disk cannot be detected due to a defect in the disk, sector detection will immediately fail if the next sector cannot be detected after a period of time approximately equivalent to the time it takes for one sector to elapse from the previous sector. Judging that 5
Obtain only the absolute position of the head on the position sensor, and
The absolute position of the head on the disk is used, which is converted using the amount of relative position deviation determined in advance.

Furthermore, if the linearity of the position information is poor and the absolute position of the head on the disk cannot be accurately obtained, as shown in FIG. Immediately before switching to the target track, that is, when the head is near 0.5 track before the target track, the absolute position of the head on the disk obtained from the absolute position of the head on the external position sensor and the relative position deviation amount determined in advance is changed. used for

Furthermore, in order to determine the absolute position of the head on the disk between sectors, first the amount of relative position deviation between sectors is estimated from the relative position deviation determined in advance. The eccentricity of the disk is large in one revolution, but the amount of movement between sectors is small, so the relative positional deviation between two sectors can be calculated by directly approximating the difference between them6.For example, if the relative positional deviation in a certain sector is ΔPne If ΔPn÷1 between the next sectors, the relative positional deviation at the middle position is (ΔPn+
It is obtained as t-ΔPn)/2. This value is also stored in memory, and the absolute position of the head on the 1-position sensor, which is used when the absolute position between sectors is required, can be obtained at any time. The relative position deviation amount is converted into the absolute position of the head on the disk.

〔Effect of the invention〕

According to this invention, in a disk device using a voice coil motor, even if a disk without servo information is used, the head can be positioned on the data track at high speed, and data can be read. The software can now be used. Furthermore, since a position signal similar to that from the disk is obtained, the control program for positioning control using the position signal from the disk can be used as is, and there is almost no increase in the amount of the program.

Furthermore, since more accurate and continuous positional information can be obtained for sector servo type disks, the position can be immediately detected even if the disk goes off track due to disturbances, etc., and the data on the adjacent track will not be erased. There is no. Furthermore, even if a sector cannot be detected due to a defect in the disk and position information cannot be obtained, accurate position can be obtained.

Furthermore, by replacing position information with poor linearity between tracks with position information from an external position sensor, accurate absolute positions of the heads on the disk can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a disk device according to an embodiment of the present invention, and FIG. 2 is a diagram showing a position signal obtained from an external position sensor and a position signal obtained from a disk according to an embodiment of the present invention, and their position signals. A diagram showing the position of gltsi,
FIG. 3 is a diagram illustrating how to determine the relative position deviation between the absolute position of the head on the external position sensor and the absolute position of the head on the disk according to an embodiment of the present invention, and FIG. FIG. 5 is a diagram showing the relationship between a servo information pattern and a position signal group obtained from the servo information pattern, and FIG. 5 is a diagram of an actual position signal obtained from a disk according to the prior art. 1...Disk, 2...Head. 3... Carriage. 4... Voice coil motor (VCM) 5... Position sensor, 6... Position signal detection circuit from disk, 7... Position signal detection circuit from external position sensor, 8... μCP
U, 9...Position tracking control circuit, IO...
Current amplifier, 11... A/D converter, 12...
- D/A converter, 13...X signal, 14-Y signal, 15...LX signal. 16...LY double signal 17...Track 00.18.
19,20.21...Relative position deviation between the absolute position of the head on the external position sensor and the absolute position of the head on the disk, 22...U signal, 23...V signal, 24
... Servo sector, 25 ... Zone signal, 26
．． 27, 28, 29-A, B, C, D signals. 30...Position signal area agent with bad linearity Patent attorney Nori Chika Ken Yudo Mitsuyuki Matsuyama t /7 h7700

Claims (3)

[Claims] (1) Servo information for head positioning that is repeated at a predetermined period is formed in a servo area of a part of the sector provided on the disk, and this servo information is generated around sampling determined by the number of sectors and the rotation speed of the disk. In a disk device that uses a head to read out each servo area, and positions the head to a target track according to a plurality of phase position signals obtained thereby, position signals for head positioning are obtained continuously and in a plurality of phases, and the servo A position sensor that can be obtained at the same repeating period as the information or an integer multiple thereof is installed outside the disk, and when a disk without the servo information is used, the position signal obtained from this position sensor is used to move the head to the target track. For a disk on which the servo information has been formed in advance, the head position on the disk is determined from the servo information obtained in the servo area of the disk at each sampling period, and the head position is determined from the servo information obtained in advance from each servo sector. The relative positional deviation amount between the head position on the disk and the head position on the position sensor is determined for each sector over one rotation of the disk, and the disk is detected using this relative positional deviation amount and the head position on the position sensor. A disk device characterized by correcting or interpolating the position of an upper head to position it to a target track. (2) Correction of the head position on the disk is based on the absolute position of the head on the position sensor, the absolute position of the head on the disk obtained from the relative position deviation amount, and the absolute position of the head on the disk obtained directly from the disk. Always compare, and if the difference is greater than a predetermined value, the absolute position of the head on the position sensor and the position of the head on the disk obtained from the relative position deviation amount are determined as the absolute position of the head on the disk obtained directly from the disk. 2. The disk device according to claim 1, wherein the disk device is used in place of a disk drive. (3) When the servo information cannot be detected in the servo sector of the disk, the absolute position of the head on the disk can be corrected using the absolute position of the head on the position sensor obtained immediately after it is determined that the servo information cannot be detected. 2. The disk device according to claim 1, wherein the absolute position of the head on the disk is determined using a relative position deviation.