JPH03134873A - Converter driving device - Google Patents

Abstract

PURPOSE:To improve accuracy for positioning to a data track and to improve the performance of a converter driving device by loading a converter for data read / write and a converter for servo information read on one rigid body and relatively moving the converter for data to the converter for servo. CONSTITUTION:A servo head 1 is connected through a fine move micro-actuator 3 to a data head 2 and they are loaded on one rigid body such as a slider 6, for example. In such a case, the servo head 1 is fixed to the slider 6 and the data head 2, however, can be moved relatively to the slider 6 and the servo head 1 by the fine move microactuator 3. Thus, when the servo head 1 is settled to a target position, the head can be settled to the target data track at high speed with high accuracy by the operation of the microactuator 3.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetic disk device and a magnetic tape device.

Concerning the conversion element drive device of information recording devices such as magneto-optical disk devices and magnetic car 1-devices, it is necessary to position the target data track with high precision, especially for large-capacity storage devices aiming at high 1-rank density. The present invention relates to an applied conversion element driving device.

(4) [Prior Art] As the capacity of conventional information recording devices, such as magnetic disk devices, increases, both the bit density and the track density become higher. Due to the increased density of racks, the track pitch is now on the order of several μm, and increasing the accuracy of positioning the transducer element (magnetic head) is becoming an increasingly important issue. In the conventional servo surface servo method, which has relatively high positioning accuracy, the servo information reading conversion element (hereinafter referred to as servo head) and the data reading/writing conversion element ( A positioning error occurs due to a positioning deviation with respect to the data head (hereinafter referred to as a data head). Therefore, one method for improving the positioning accuracy of the servo system is to provide a positioning means for only the head element, separate from the positioning means by the head actuator, as a means for correcting the positional deviation between the servo head and the data head. For example, it is shown in Japanese Patent Application Laid-Open No. 62-250570J.
5) It is used for positioning, and a fine positioning actuator is placed near the magnetic head.

[Problem to be solved by the invention]

However, the above technology is based on the premise of having a servo surface in addition to the data surface, and its purpose is to compare and correct the positional deviation between the head position determined by the servo head and the actual data track. 1 to rack l-1] design and control system design that takes into consideration the vibration transmission characteristics and temperature difference between the servo head and the data head,
Conditions for transfer functions, compensation circuits, etc. are becoming stricter for higher track densities.

An object of the present invention is to provide a conversion element drive device that reduces the above-mentioned positional deviation and improves transmission characteristics.

[Means for solving the problem] The above objective can be achieved as follows. A head is configured in which a servo head and a data head are mounted on the same slider. Here, the servo head is fixed on the slider, and the data head (6) is configured to be movable relative to the servo head by a microactuator.

At this time, the operating characteristics of the microactuator are 100
It is necessary to have a wide band of Hz to several tens of kilohertz. On the other hand, the servo band of a coarse motion actuator has a crossover frequency of several hundred Hz to several kHz at most, depending on the size of its movable mass and mechanical characteristics such as friction of the bearing guide.

Therefore, the coarse movement actuator is responsible for access.
The configuration is such that the micro-actuator is in charge of the cell-ring vibration during settling and the following operation. On the other hand, on the data surface, for example, servo information is recorded one track at a time between data zones of a predetermined number. A pattern is recorded on the medium. Alternatively, in a two-layer film medium, it is also possible to record data information and servo information in separate layers, and the latter is more promising when considering the utilization efficiency of the medium surface.

[Effect]

The servo (7) head that receives the instruction to access the target track performs a positioning operation to the target servo track having the target data track zone according to a predetermined speed curve. When the servo head settles to the target position, an access command to the target data track is also issued to the microactuator that moves the data head, and in response, the data head moves to the target data track by operating the microactuator based on the predetermined address information. It is settled to the data track at high speed and with high precision. During following, the servo head follows the servo track according to the transmission characteristics of the coarse movement actuator, and the data head follows the target data track according to the transmission characteristics of the microactuator.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the basic configuration of first to third embodiments of the present invention. The servo head 1 is connected to a data head 2 via a fine movement microactuator 3, and these are mounted on one rigid body, for example, a slider 6. This slider 6 is connected to a cymbal spring 7 for coarse movement, for example, to a VCM actuator 4.
etc. are connected via. The VCM actuator 4 is fixed to the housing 5 directly or via a spring 9. Further, the servo head 1 and the data head 2 are held at a predetermined distance from a storage medium, for example, a magnetic disk 8 that rotates at high speed. Here, the servo head 1 is fixed to the slider 6, but the data head 2 can be moved relative to the slider 6 and the servo head 1 by a fine movement macro actuator 3. The desired value of relative motion stroke is related to the pattern of servo and data information, which will be discussed next.

FIG. 2 is a diagram schematically showing the pattern of the servo 1-rack and data tracks on the magnetic disk 8. As shown in FIG. Servo tracks 9a, 9b, 9c are regularly arranged at predetermined intervals, and data zones 10a, 10b each including a predetermined number n of data tracks are arranged between them. The width of the data zone is expressed as (9) where p is the data track pitch, nXp. This size is the size of the microactuator 3.
approximately equal to the stroke of

In consideration of improving the quality of servo signals, it is convenient to make the servo track width relatively wider than the data track width. In this case, a large area is taken up in the servo area, resulting in poor utilization efficiency of the medium surface. Effective use of media will be discussed in detail later.

FIG. 3 is a block diagram of the two-stage coupled servo system of the present invention. Let the target value be X, the displacement of the data head be Xs, the error be Xer, and the characteristic of the compensation circuit 31 that compensates for the stability of the fine movement actuator be acl(s). The output is eS, and in the fine movement microactuator system, the characteristic is a 1
4(S) compensation circuit 32 and the disturbance Fcl added to it,
The transfer function 33 of the fine movement microactuator is Gf+n
If e(S), the displacement caused by the fine movement microactuator will be Xf. On the other hand, the coarse movement actuator system includes a compensation circuit 34 with a characteristic of Gc3(s) and a disturbance (1
0) Fd', the transfer function 35 of the coarse actuator is Gco
arse(s), the displacement by the coarse movement actuator will be Xc. The output Xs can be expressed as the sum of the amount of movement Xf of the data head by the fine movement actuator and the amount of movement Xc of the servo head by the coarse movement actuator. With this configuration, low-frequency fluctuations such as friction of the actuator and external vibrations can be suppressed by the control loop of the coarse movement actuator.

In addition, when it is required to follow a servo pattern track fixed on the surface of a medium such as a discrete medium, the low frequency large amplitude component which is the main component of track eccentricity,
The coarse actuator can follow.

FIG. 4(a) schematically shows the open loop characteristics of the conventional servo surface servo type actuator, FIG. 4(b) shows the open loop characteristics of the coarse movement actuator of the present invention, and FIG. 4(c) The open-loop characteristics of the micro-actuator for fine movement of the present invention are each schematically shown in FIG. The transfer characteristics of the conventional actuator (11) have a crossover frequency 41 of a little less than 1 kHz, and a phase margin of 50 degrees or more. In the present invention, the actuator for coarse movement has characteristics similar to those shown in FIG. 4(a), but the gain is set particularly high at the low frequency range 42. On the other hand, the actuator for fine movement has a crossover frequency 43 of several kHz and can have a phase margin of several tens of degrees. By assigning the low frequency range to the coarse movement actuator and the high frequency range to the fine movement actuator, stable characteristics can always be obtained over a wide band. Therefore,
By combining these characteristics (a) and (b), it is possible to design a servo system with a sufficiently large band.

FIG. 5 is a diagram schematically showing the slider portion of the first embodiment of the present invention. The servo head 51 has a slider 5
The data head 52 is fixed to a movable member 54 via an actuator 53 such as a laminated piezo element.
” is installed in the second.

The movable member 54 includes an actuator 53 and a shock absorber (12
) is supported by the material 56, and the running direction of the slider,
That is, it can move at right angles to the 1-rack direction. However, if the laminated piezo element used as an actuator is large enough to be mounted on the slider 55 using the method of this embodiment, the stroke is very small, several μm, and the stroke is about submicron due to mechanical vibrations. Although it is possible to absorb positioning errors, it is not suitable for accessing data tracks or following eccentricity.

FIG. 6(a) is a diagram schematically showing a slider portion of a second embodiment of the present invention. The servo head 61 is fixed on a slider 64, and the data head 62 is mounted on a microactuator 63. The microactuator 63 is a movable part of an electrostatic linear motor made by microapplication technology applying semiconductor technology. With this actuator, several meters
Since the stroke is several millimeters with the ln square dimension, it can be used as an access actuator.

FIG. 6(b) shows the slider (13) of the third embodiment of the present invention.
) FIG. The servo head 65 is fixed on the slider 68, and the data head 66
a, 66b, 66c, - are mounted on the same microactuator 67-1- as above. Assuming that the distance between each data head is an integer multiple of data 1 to rack pitch, when one data head is set on a predetermined track, the remaining data heads can also be set on their respective data tracks at the same time. can. That is, the positioned data heads can be regarded as if they were all on one cylinder.

Therefore, with this configuration, an improvement in throughput is expected.

FIG. 7 is a diagram schematically showing an example of a linear electrostatic motor used as a fine movement microactuator of the present invention. FIG. 7(a) is a first example, which is a cross-sectional view of a linear electrostatic motor.

The servo head 71 is fixed on the so-called stator part 74 of the electrostatic motor or together with the stator 74 on the slider 73. The data head 72 is formed on a so-called rotor part 75 of a static (14) electric motor. The rotor 75 is supported by a spring member 76 having appropriate rigidity.
It is coupled onto the slider 73.

By storing electric charge in the stator 74 and rotor 75,
The effective electric field areas of the electrodes of the rotor 74 and stator 75 change due to the electrostatic force, and the rotor 72 moves while maintaining balance with the spring 76.

FIG. 7(b) shows a second example of a linear electrostatic motor, and is a front view of the shape formed on the slider.

The data head 77 is formed on a rotor 78 of an electrostatic motor that moves linearly along a guide rail 80, and a stator 79 is fixed on a slider.

Electrodes 781, 782°, etc. formed on the rotor 78 are similar to electrodes 791°, 79°, formed on the stator.
2.793. ..., and the rotor 78 is moved by electrostatic force by sequentially switching the polarity of adjacent electrodes. Such a structure can be formed at the same time as the magnetic head 77 using semiconductor technology.

FIG. 8 is a diagram showing an embodiment of the application method of the present invention. First, when an address designation 81 to a predetermined data track is issued, the servo head accesses 82 a servo track having a zone including the data track while counting cross-tracks. After the servo head is positioned to the servo track 83 and settled under closed-loop control, the data head is moved 84 by calculating the distance from the position with respect to the servo head according to predetermined address information, and is then positioned and settled. 85. In this method, the servo head is set to the servo track 8.
After 3, open-loop control is performed, which is not suitable for ultra-high track density.

FIG. 9 is a diagram showing another embodiment of the application method of the present invention. First, an address command 9 to a predetermined data track is given.
When a 1 is issued, the servo head accesses 92 the servo 1-rack whose receiver has the zone containing that data track. After the servo head has positioned 93 to the servo l-rack and settled under closed-loop control, the data head moves to a predetermined data rack based on the sector servo information in the zone or the embedded servo information. It is moved 94 for precise positioning and settled under closed loop control.

FIG. 10 is a diagram showing another embodiment of the application method of the present invention. First, when an address command 101 to a predetermined data track is issued, the servo head accesses 102 a servo track that has a zone including that data track. The servo head is coarsely positioned 103 to the servo track and settled under closed loop control. In parallel with this, the data head performs an access operation 104 to a predetermined data track, performs precise positioning under closed loop control based on sector servo information within the zone or embedded servo information, and settles.

FIG. 11 is a diagram schematically showing one example of the format 1 of the medium surface applied to the embodiment shown in FIG. 9 or FIG. 10. The pattern of recorded information is the servo track zone 111 of the present invention and the sector servo information 112.
and a data zone 113. During access, the servo head cross-track counts the (7) servo tracks 111, so the seek time is significantly reduced compared to the conventional sector servo system.

FIG. 12 is a diagram showing the structure of another example of the medium applied to the embodiment shown in FIG. 9 or FIG. 10.

The structure is such that data 121 is recorded on the surface layer of the medium, and servo information 122 is recorded on the lower layer. The rank of servo 1, which has a receiver for each zone, is also recorded on the medium surface layer 123. That is, the servo track 123 is a track for the servo head to follow, and the servo track 122
is the track for the data head to correctly follow track '2'.

FIG. 13 is a diagram showing an example of another structure of the medium applied to the embodiment shown in FIG. 9 or FIG. 10. Only data 131 is recorded on the surface layer of the medium. With this method, data information can also be recorded on the second layer of the servo information 132 in the lower layer, and the medium surface is used efficiently. Furthermore, the first
When using the embedded servo method explained in Figures 2 to 13, the writing frequencies of the data signal and servo signal are changed, and both signals read at a time are separated by a filter circuit. There is a need. In addition, quality can be improved by changing the characteristics of the magnetic films of the data layer and servo layer, such as coercive force and saturation magnetization, and by appropriately setting the shape and material of the data spatula I- and servo head, such as gap length and saturation magnetic flux density. A good servo signal can be extracted. -For example,
The magnetic film of the lower servo layer has a smaller coercive force than the magnetic film of the upper data layer, and the gap length and saturation magnetic flux density of the servo head are smaller than those of the data head. If a large one is used, a spatula/medium system with good characteristics can be obtained.

In devices with stacked media, problems arise in data plane servo. FIG. 14 is a diagram for explaining the problems of the data surface servo method in the stack device. Even if the servo head 141a is positioned on a predetermined servo track 142a, other servo heads 14], b.

(19) 14-1c is not always accurately positioned on the servo tracks 14.2b and 14.2c due to thermal displacement or the like. If each head is on the same cylinder, throughput is improved by reading information from each head at once. Therefore, even if the servo head position shifts, it is sufficient that each data head is on the same cylinder. Therefore, even if the servo head is not positioned at the optimal position, it is sufficient as long as the data head is positioned on a predetermined track. Positioning may be performed for each slider.

At this time, if the amount of positional deviation of the servo head is within the movable range of the data head, the data head can be positioned.

However, if the amount of positional deviation is greater than the movable range of the data head, the data head cannot be positioned.

As another solution to the problem of the data surface servo method, as shown in FIG. 156a, 156b, 1-56c,
- second actuator for coarse movement on the slider support member connected to -52a, 152b, 15
2c, -, servo heads 154a, 154b, 154c, -, fine movement actuators 153a, 153b, 153 provided on each slider.
c, -, data heads 155a, 155b, 15
5c.

, the coarse movement actuator 1.52 a , ],
52b.

152c, . . . , each slider is individually moved. The amount of positional deviation of each servo head is detected and immediately corrected for each slider by the coarse movement second actuator. At this time, the coarse movement actuator 152a.

152b, 152c, . . . move only when a positional shift of the servo head occurs. Or, the first coarse movement actuator 151 and the second coarse movement actuator 1.52 a , 152 b , 152 c .

..., and fine movement actuators 1.53a, 153
b.

153c, . . . may be used as a three-stage actuator, each having a low frequency region, a middle frequency region (21) region, and a high frequency region for driving, but the circuit configuration would be complicated.

〔Effect of the invention〕

According to the present invention, for example, it is possible to significantly improve the positioning accuracy of data 1 to rank in stacked magnetic disk drives, and to improve the data access speed at high TPI. This is an important technical factor that greatly increases the possibility of increasing the track density of magnetic recording files.
This greatly contributes to improving the performance of the device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the first to third embodiments of the present invention, FIG. 2 is a diagram schematically showing the basic structure of the writing pattern of the servo track and data track of the embodiment of the present invention, and FIG. is a block diagram of the two-stage coupled servo system of the present invention, FIG. 4 is a club diagram showing the oven loop characteristics of each servo system, and FIG.
6 and 6 are diagrams schematically representing the configurations of the two-stage coupled servo systems of the first to third embodiments of the present invention, and FIG. 7 is the structure and operation of the fine movement microactuator of the present invention (22). FIGS. 8 to 10 are schematic diagrams for explaining the method, and FIGS.
3 is a diagram schematically showing various examples of servo and data track patterns of the present invention, FIG. 14 is a schematic diagram for explaining problems in applying the present invention to a medium stacking device, and FIG. 15 is a diagram schematically showing various examples of servo and data track patterns of the present invention. FIG. 1 is a configuration diagram of an apparatus for explaining an example of a method for solving the above problem. servo head, 2... data spatula l-', 3... fine movement micro actuator, 4... coarse movement micro actuator, 5... housing, 6... slider, 8... disk,
9a, 9b, 9c - servo track, 1
0a. 10b・Data 1 Herakku Zone, 31, 32.34・
... Compensation circuit, 33... Transfer function of fine movement actuator, 35... Transfer function of coarse movement actuator, 41.
Crossover frequency of conventional device, 43. Crossover frequency of fine movement microactuator of the present invention, 51.
．． 61.65... Servo head, 52°62, 66
a, 66 b, 66 c - data head, (2
3) 53.63.67...actuator, 55,64°68...slider, 71...servo head, 72°7
7...Data head, 74.79 - Stator, 7
2.78・Rotor, 81. 94. , 111-・
Address specification, 82, 92, 112 Access (cross 1 to rank count), 83, 93, 113 - Servo head setting, 84. ．． 94. ．． 114 ・Rad seek operation to data, 85, 95, 11.5...Data head setting, 101. ．． 123... Servo 1 ~ Easy, 10
2... Sector servo information, 122, 132... Embedded servo information, 103, 1.21, 131... Data track, 14]a, 14-1. b, 141c, 154a. 1541), 154c, - Servo Yatsu 1ku, 1.4
2 a. ]-42b, 142c-Servo 1~Rack, 1.
51-th” coarse movement actuator, 1.52a, 1
52b, ], 52o, ... second coarse movement actuator, ], 53 a, ] 53 b, 1-
53 c, - Fine movement actuator. (24) Figure U ((2-) Zf2Z (b) Figure 0-Z ¥9 Figure JP-A-134873 (10) Tomi 1 Figure ll

Claims (1)

[Claims] 1. Arranged on a recording medium on which servo information is written,
In a conversion element driving device used in an information recording device that reads or writes information using a conversion element that moves relative to the recording medium, a conversion element for reading and writing data and a conversion element for reading servo information are provided. 1. A conversion element driving device, which is mounted on one rigid body and configured such that the data conversion element moves relative to the servo conversion element. 2. A recording medium in which data tracks on which information is recorded form a recording data area with a fixed number of tracks, and servo tracks on which servo information is recorded are arranged between each area,
A conversion element positioning apparatus, characterized in that the conversion element driving apparatus according to claim 1 is used to position a data conversion element on a predetermined data track. 3. A servo device for positioning a conversion element for reading and writing data in a recorded data area on a recording medium,
a servo conversion element for positioning on a servo track having servo information on the recording medium; a data conversion element disposed close to the servo conversion element and movable relative to the servo conversion element; a rigid body on which a servo conversion element and a data conversion element are mounted; a coarse movement mechanism for moving the rigid body; and a first part for positioning and settling the servo conversion element on a predetermined servo track on the recording medium. A servo device comprising: a servo means; and a second servo means for positioning the data conversion element on a predetermined data track. 4. In the recording data area, servo tracks containing servo information are provided at regular track intervals, and when the servo conversion element follows the servo track and the data conversion element positions the target data track, the above-mentioned 4. The servo apparatus according to claim 1, further comprising means for relatively moving the data conversion element by a predetermined distance with respect to the position of the servo conversion element. 5. A plurality of sector areas containing servo information are provided in the recording data area, and when the servo conversion element follows a servo track and the data conversion element positions the target data track, the servo conversion element 4. The servo apparatus according to claim 3, further comprising means for positioning the data conversion element using positioning information divided into a plurality of sectors based on the position of the data conversion element. 6. At least the recorded data area has a two-layer structure of a layer in which servo information is recorded and a layer in which data is recorded, so that the servo conversion element follows the servo track, and the data conversion element follows the target data track. 4. The servo apparatus according to claim 3, further comprising means for positioning the data conversion element based on the position of the servo conversion element based on positioning information of the servo layer. 7. The data conversion element that moves relative to the servo conversion element is moved relatively by a piezoelectric actuator using a piezoelectric element or an electrostatic motor using microfabrication technology or semiconductor technology. A servo device according to any one of claims 1 to 6. 8. The servo device according to any one of claims 1 to 7, wherein a plurality of the data conversion elements are mounted on the rigid body.