JPH05101558A - Head actuator and its driving device - Google Patents

Abstract

PURPOSE:To improve the controllability of an actuator by attaching a magnetic flux detecting element to the actuator and adding the absolute positional information and the speed information of the actuator found from the magnitude of detected magnetic flux to a control loop. CONSTITUTION:This actuator is constituted of the movable part R of a coil 7 providing an arm 9 supporting a head 12 and a fixed part S providing permanent magnets 3-6 opposing to the movable part R. Further, the magnetic flux detecting element 13 is attached on the bobbin 8 of the movable part R and the magnetic density of a magnetic circuit gap G is detected by the element. Then, a driving device 50 is constituted of a position detecting circuit 53 finding the position of the movable part R from a signal from the element 13, a speed detecting circuit 54 operating the speed of the movable part R from the positional information and a head actuator control circuit 55 positioning and controlling the head from these information. By this constitution, the controllability of the head actuator is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head actuator and its drive device, and more particularly to a head actuator for accessing a sector servo type recording medium and its drive device. 2. Description of the Related Art Conventionally, a magnetic disk device has been used as an external storage device of a computer or the like, and the magnetic disk device is required to have a large capacity and a high speed access. In conventional magnetic disk devices, especially large hard disk devices, a plurality of information recording disks and one servo disk are coaxially mounted and rotating, and the track written on this servo disk is used. By reading the information with the servo head, the positioning of another data head that is integrally driven in conjunction with the servo head has been performed.

On the other hand, in recent years, small-sized magnetic disk devices having a small number of recording media mounted are increasingly adopting a sector servo system without such a specific servo surface, and the controllability of actuators of this sector servo system is increasing. Improvement is desired.

[0003]

2. Description of the Related Art The sector servo system is a system in which servo information is obtained from servo sectors written almost every data sector on a data surface. In a magnetic disk adopting such a sector servo system, since servo information is obtained from servo sectors, the controllability improves as the number of servo sectors increases. Therefore, in the conventional sector servo type magnetic disk device, the number of servo sectors is increased,
Alternatively, an external encoder or the like is added to the positioner movable portion to detect the absolute position or speed, and by adding this to the control loop, fine control of the actuator can be performed with less sector servo information. Also,
Another method has been considered in which the speed of the actuator is detected using a search coil and is added to a control loop to perform fine control of the actuator.

[0004]

However, the method of increasing the number of servo sectors and increasing the amount of writing servo information has a problem of conversely decreasing the storage capacity.
In addition, the method of using an external encoder causes an increase in the number of parts, a decrease in reliability, an increase in cost, an increase in installation space, and the like, and the signal is susceptible to noise and the controllability is not so improved. was there. Further, in the method of detecting the speed of the positioner using the search coil, there is a problem that the signal obtained in this method is susceptible to the noise of the actuator because the detected voltage level is very low.

Therefore, according to the present invention, there is no problem that the stored information decreases due to the increase of servo information on the data surface, the increase of the number of parts is prevented as much as possible, the reliability is improved, the cost increase is suppressed, and the installation space is reduced. An object of the present invention is to provide a head actuator capable of preventing increase and improving controllability of a magnetic disk device without being affected by actuator noise, and a drive device thereof.

[0006]

A first form of a head actuator of the present invention that achieves the above object is a disk having a head for reading and writing information for at least one recording medium. In a storage device, a moving actuator of a head type for moving the head to a target track on the recording medium, the moving coil-type moving part having an arm for supporting the head, and the moving part provided opposite to the moving part. It is characterized by comprising a fixed portion provided with a permanent magnet and at least one magnetic flux detection element attached to the movable portion and detecting the magnetic flux density of the magnet of the fixed portion.

A second form of the head actuator of the present invention which achieves the above object, is a disk storage device comprising a head for reading and writing information for at least one recording medium, A head actuator for moving the head to a target track on the recording medium, comprising a movable part of a movable magnet type having an arm for supporting the head, and a coil provided facing the movable part. It is characterized by comprising a fixed portion and at least one magnetic flux detection element which is attached to the fixed portion and detects the magnetic flux density of the magnet of the movable portion.

In the above structure, a plurality of the magnetic flux detecting elements are attached so that the region having the linearity of the output characteristic of each magnetic flux detecting element is continuous within the moving range of the movable section, and the moving section moves. By selecting a predetermined magnetic flux detecting element according to the position, the magnetic flux density change characteristic in the linearity region may be always obtained.

A first form of a head actuator driving device of the present invention that achieves the above object is the head actuator driving device according to claim 1 or 2, wherein the magnetic flux density from the magnetic flux detecting element is A position detection circuit for the movable part which is calculated by calculating the operating position of the movable part according to a signal; a speed detection circuit which is calculated for the speed information of the movable part of the head actuator from the obtained position information; A positioning control circuit for positioning the head by controlling a current flowing through a coil of the actuator based on a detected value of the position information written on a recording medium from the head and the speed information. And

A first form of a head actuator driving device of the present invention that achieves the above object is the head actuator driving device according to a third aspect of the invention, wherein the plurality of head actuator driving devices are provided in accordance with the position of the head. Magnetic flux detecting element selection circuit for selecting one of the outputs of the magnetic flux detecting element, and the movable portion of the movable portion obtained by calculating the operating position of the movable portion according to the magnetic flux density signal from the selected magnetic flux detecting element. A position detection circuit, and a speed detection circuit that calculates and obtains speed information of the movable portion of the head actuator from the obtained position information,
A positioning control circuit for positioning the head by controlling the current flowing through the coil of the actuator based on the detected value of the position information written on the recording medium from the head and the speed information. Characterize.

[0011]

According to the head actuator and the driving device thereof of the present invention, the magnetic flux is detected by the magnetic flux detecting element attached to the movable portion of the actuator, and the magnitude of the magnetic flux detects the magnetic flux density of the magnetic circuit measured in advance. The absolute position of the actuator can be recognized according to the position characteristic. Then, the moving speed of the actuator is obtained from the detected position information, and the controllability of the actuator is improved by adding the absolute position information and the speed information to the control loop of the control circuit.

[0012]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows the configuration of a first embodiment of a head actuator of the present invention. In this figure, a moving coil type straight-ahead head actuator 10 is shown.
In the figure, S is a fixed portion, which is composed of yokes 1 and 2 and permanent magnets 3, 4, 5, and 6. Also, R
Is a movable part, and the gap G of the permanent magnets 3, 4, 5, 6
The coil 7 includes a coil 7 that moves between them, a bobbin 8 that holds the coil 7, an arm 9 that projects from the bobbin 8, and a carriage 11 that is provided at the tip of the arm 9 and supports a head 12. These are all existing.

In the head actuator 10 having the above structure, in this embodiment, the magnetic flux detecting element 13 is attached to the central portion of the bobbin 8 so that the magnetic flux in the magnetic circuit gap G can be detected. A Hall element or an MR element can be used as the magnetic flux detecting element 13. It should be noted that the magnetic flux detecting element 13 is attached to the bobbin 8 of the movable portion R because this embodiment is of the moving coil type. However, when the linear head actuator is of the moving magnet type, the magnetic flux detecting element 13 is used. Is the fixed part S
It is attached around the side coil and detects the magnetic flux of the movable magnet.

FIG. 2 shows the output characteristic of the magnetic flux detecting element 13 in the head actuator 10 of FIG.
It shows the magnetic flux density of the gap G of the permanent magnets 3, 4, 5 and 6 when the position on the front end side of the fixed portion S is 0 and the rear end side of the fixed portion S is the x direction. As can be seen from this figure, in the magnetic flux density detected by the magnetic flux detecting element 13 with the movement of the movable portion R, there is a linear region in which the output of the magnetic flux detecting element 13 changes linearly with respect to the position of the movable portion R. I know there is. Therefore, in this portion, the absolute position of the movable portion R can be specified by the detected magnetic flux density.

FIG. 3 is an assembled perspective view showing the configuration of the second embodiment of the head actuator of the present invention. In this figure, a movable coil type swing head actuator (voice coil motor, also called VCM for short) is shown. ) 20 is shown. In the figure, S is a fixed part, and the yokes 21, 2
2, and permanent magnets 23, 24, 25, 26 and side yokes 27, 28, 29, 30.
Further, R is a movable portion, and includes a base portion 32 provided with a through hole 31 to which a rotating shaft (not shown) is attached. There is a carriage 35 that supports
On the opposite side, a bobbin 37 having an annular coil 36 attached inside is projected. The coil 36 of the movable part R is adapted to move between the gaps G of the permanent magnets 23, 24, 25 and 26. All of these configurations are existing.

In the head actuator 20 having the above-described structure, in this embodiment, the magnetic flux detecting element 38 is embedded in the central portion of the bobbin 37 on the side farthest from the rotation axis, and the magnetic flux in the magnetic circuit gap G is absorbed. It can be detected. A Hall element or an MR element can be used as the magnetic flux detecting element 38. Further, although one magnetic flux detecting element 38 is embedded in this embodiment, a plurality of magnetic flux detecting elements may be embedded in the bobbin 37. For example, it is possible to embed the two magnetic flux detecting elements 39A and 39B or the two magnetic flux detecting elements 40A and 40B at positions indicated by broken lines.

Since the embodiment of FIG. 3 is of the movable coil type, the magnetic flux detecting element 38 is attached to the bobbin 37 of the movable portion R, but when the swing head actuator is of the movable magnet type. The magnetic flux detecting element 38 is attached to the periphery of the coil on the fixed portion S side and detects the magnetic flux of the movable magnet. FIG. 4 shows the output characteristics of the magnetic flux detecting element 38 in the head actuator 20 of FIG. 3, and a line passing through the center point of the rotation axis of the movable portion R and the center of the fixed portion S is set to 0 °, and from this line The deflection angle of the movable part R is θ
In this case, the magnetic flux density of the gap G of the permanent magnets 23, 24, 25, 26 is shown. As can be seen from this figure, in the magnetic flux density detected by the magnetic flux detecting element 38 with the swing of the movable portion R, the output of the magnetic flux detecting element 38 is linear with respect to the position (deflection angle) of the movable portion R. It can be seen that there is a changing linear region. Therefore, in this portion, the absolute position of the movable portion R can be specified by the detected magnetic flux density.

FIG. 5 is a block diagram showing an example of the configuration of the drive device 50 for the head actuators 10 and 20 constructed as shown in FIG. 1 or 3. A signal from the servo sector of the recording medium is input to the drive unit 50, and a linear area determination circuit 51 that determines whether or not the head is positioned in the linear area based on the input signal, and the linear area determination circuit 51. AND circuit 52 to which a signal from the magnetic flux detection element 38 is input, and a position detection circuit 53 that detects the position of the head based on the output from the AND circuit 52.
, A speed detection circuit 54 for detecting the moving speed of the head from the output of the position detection circuit 53, and a head actuator control circuit 55.

The position detecting circuit 53 stores in advance the magnetic flux density distribution characteristics shown in FIG. 2 or FIG. 4 corresponding to each head actuator in the form of a table or an expression. The absolute position of the head is detected by the input signal. Speed detection circuit 54
Detects the speed of the head by differentiating the calculated absolute position of the head. Then, the absolute position information and the speed information thus obtained are added to the control information of the actuator obtained from the position information written in the servo sector of the recording medium, and the resultant information is added to the control loop of the head actuator control circuit 55. The controllability of the head actuator of the actuator control circuit 55 can be improved.

The head actuator control device having the above-described structure is particularly effective for a magnetic disk that is accessed at high speed, because servo information is apt to be insufficient especially when performing high speed access. Depending on the configuration of the magnetic circuit of the head actuator, it is not always possible to use only the region where the gap magnetic flux density distribution is linear,
There are cases where the above-mentioned linear region cannot cover the entire swing range of the movable portion R of the head actuator. In such a case, the relationship between the curve of the gap magnetic flux density and the non-linear region of the position is stored in the form of a table or the like, and the position information and the velocity information can be obtained by referring to this table. In this case, the swing range of the movable portion R of the head actuator can be expanded to the range from the peak point to the peak point of the gap magnetic flux density distribution curve.

When the magnetic characteristics of the magnetic circuit and the characteristics of the detection element depend on temperature, it is necessary to compensate for this.
A temperature compensation table or the like may be prepared inside the position detection circuit. Further, the shape of the coil is not limited to the above-mentioned embodiment, and may be a horizontal flat coil type or a vertical flat type. FIG. 6 shows output characteristics when two magnetic flux detecting elements 39A and 39B are used in the head actuator 20 of FIG. 3, and a line passing through the center point of the rotating shaft of the movable portion R and the center point of the fixed portion S is shown. The graph shows the magnetic flux density of the gap G of the permanent magnets 23, 24, 25, and 26, where 0 ° and the deflection angle of the movable portion R from this line are θ. As can be seen from this figure, since the two magnetic flux detecting elements 39A and 39B are mounted at positions displaced from the center of the bobbin 37, they are detected by the magnetic flux detecting elements 39A and 39B as the movable part R swings. In the linear region of the magnetic flux density, one magnetic flux detecting element 38
It shifts compared to the case where it is attached to the central part of 7.
In this embodiment, the center point of the rotary shaft of the movable part R and the fixed part S
The two magnetic flux detecting elements 39A and 39B are attached at positions displaced from the center of the bobbin 37 on both sides so that this linear region is continuous with respect to a line of 0 ° passing through the center of. Therefore, if the boundary of the linear region is exactly on the line of 0 ° passing through the center point of the rotation axis of the movable part R and the center point of the fixed part S as shown in FIG. It is twice as large as the above, and the absolute position of the movable portion R can be specified by the detected magnetic flux density in a wider swing range of the movable portion R.

FIG. 7 shows that the output characteristics of FIG.
When the two magnetic flux detecting elements 39A and 39B are attached at positions displaced from the center of the bobbin 37, the head actuator 10 configured as shown in FIG. 1 or FIG.
It is a block diagram which shows an example of a structure of the drive device 70 of 20. This drive device 70 is different from the drive device 50 of FIG. 5 in that a signal selection circuit 71 is provided in the preceding stage of the position detection circuit 53 and that the linear region determination circuit 51 selects two magnetic flux detection elements 39A and 39B. Only the signal is output, and the remaining position detection circuit 53, speed detection circuit 54, and head actuator control circuit 55 have the same configuration and operation. Omit it.

The servo sector signal from the recording medium is input to the linear area determination circuit 51, and the input signal
The linear area determination circuit 51 determines which of the two magnetic flux detection elements 39A and 39B the linear area is located in, and outputs the selection signal to the signal selection circuit 71. The signal selection circuit 71 includes two magnetic flux detection elements 39A and 39B.
From the linear area determination circuit 51, the signal selection circuit 71 inputs the output signal of either of the linear areas of the two magnetic flux detection elements 39A and 39B to the position detection circuit 53. .. The position detection circuit 53 has two magnetic flux detection elements 39A and 39B.
Magnetic flux density-deflection angle characteristics in the linear region of
Alternatively, it is stored in the form of an equation, and the absolute position of the head is detected according to the input signal. The subsequent operation is the same as that of the apparatus shown in FIG.

Thus, the two magnetic flux detecting elements 39A,
By disposing 39B on the bohing 37 so that the linear regions are continuous, the range in which absolute position information can be obtained can be widened, and the controllability of the head actuator can be further improved.

[0025]

As described above, according to the present invention,
By obtaining absolute position information and further speed information from the magnetic flux density of the permanent magnet, an encoder for obtaining speed information is not required, so the number of parts can be reduced, reliability can be improved, and space can be reduced to reduce the size of the device. Therefore, there is a significant effect in improving the positioning controllability of the head actuator, and there is an effect that it greatly contributes to improving the performance of the magnetic disk device.

[Brief description of drawings]

FIG. 1 is a sectional view of a head actuator according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an output characteristic of the magnetic flux detecting element of FIG.

FIG. 3 is an assembled perspective view showing a configuration of a head actuator of a second embodiment of the present invention.

FIG. 4 is a diagram showing a deflection angle-magnetic flux density characteristic of the head actuator when one magnetic flux density detecting element is attached to the head actuator of the embodiment of FIG.

5 is a configuration diagram of an example of a drive device of the head actuator of FIG. 1 or FIG.

FIG. 6 is a diagram showing a deflection angle-magnetic flux density characteristic of the head actuator when two magnetic flux density detection elements are attached to the head actuator of the embodiment of FIG.

[FIG. 7] Two magnetic flux density detection elements for the head actuator
It is a block diagram of an example of the drive device of the head actuator of FIG. 1 or FIG.

[Explanation of symbols]

1, 2 ... Yoke 3, 4, 5, 6 ... Permanent magnet 7 ... Coil 8 ... Bobbin 9 ... Arm 10 ... Head actuator of the first embodiment of the present invention 11 ... Carriage 12 ... Head 13 ... Magnetic flux detection element 20 ... Head actuator (voice coil motor) 21 of the second embodiment of the present invention 21, 22 ... Yoke, 23, 24, 25, 26 ... Permanent magnets 27, 28, 29, 30 ... Side yoke R ... is movable part S ... Fixed Part 31 ... Through hole 32 ... Base part 33 ... Arm 34 ... Head 35 ... Carriage 36 ... Coil 37 ... Bobbin 38, 39A, 39B, 40A, 40B ... Magnetic flux detection element 50, 70 ... Drive device 51 ... Linear area determination circuit 53 ... Position detection circuit 54 ... Speed detection circuit 55 ... Head actuator control circuit 71 ... Signal selection circuit

Claims (7)

[Claims] 1. A disk storage device comprising a head for reading and writing information from and to at least one recording medium, the head actuator moving the head to a target track on the recording medium. A movable part of a movable coil type having an arm for supporting the head, a fixed part provided with a permanent magnet facing the movable part, and a magnet of the fixed part attached to the movable part. At least one magnetic flux detecting element for detecting the magnetic flux density of the head actuator. 2. A disk storage device comprising a head for reading and writing information for at least one recording medium, the head actuator moving the head to a target track on the recording medium. A movable part of a movable magnet type having an arm for supporting the head, a fixed part having a coil provided facing the movable part, and a magnet of the movable part attached to the fixed part. A head actuator comprising: at least one magnetic flux detection element for detecting a magnetic flux density; 3. A plurality of the magnetic flux detecting elements are attached so that a region having linearity of output characteristics of each magnetic flux detecting element is continuous within a moving range of the movable section, and the magnetic flux detecting elements are attached according to a moving position of the movable section. The head actuator according to claim 1 or 2, wherein the magnetic flux density change characteristic of the linearity region is always obtained by selecting a predetermined magnetic flux detecting element. 4. The head actuator drive device according to claim 1, wherein the position of the movable portion is calculated by calculating the operating position of the movable portion in accordance with a magnetic flux density signal from the magnetic flux detection element. A detection circuit, a speed detection circuit that calculates the speed information of the movable part of the head actuator from the obtained position information, a detection value from the head of the position information written on the recording medium, and the speed information. And a positioning control circuit for positioning the head by controlling the current flowing through the coil of the actuator. 5. A table of the relationship between the position of the head and the magnetic flux density in a region where there is no linearity in the change of the magnetic flux density is provided, and position information and velocity information of the head outside the linearity region are obtained from this table. The drive device for the head actuator according to claim 4, wherein 6. The temperature detecting element for measuring the environmental temperature of the magnetic flux detecting element, and the temperature compensating circuit for compensating the temperature of the output of the magnetic flux detecting element according to the detected temperature. Alternatively, the drive device for the head actuator according to Item 5. 7. The drive device for a head actuator according to claim 3, further comprising a magnetic flux detection element selection circuit that selects one of outputs of the plurality of magnetic flux detection elements according to a position of the head. , Depending on the magnetic flux density signal from the selected magnetic flux detection element,
A position detection circuit for the movable part which is calculated by calculating the operating position of the movable part; a speed detection circuit which is calculated by calculating the speed information of the movable part of the head actuator from the obtained position information; A position control circuit for positioning the head by controlling a current flowing through a coil of the actuator based on a detected value of the position information from the head and the speed information. Drive.