JP2001076443A - Driving device using electro-mechanical conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positioning mechanism of a head suitable for writing/ reading information on/from a super high-density recording medium such as an HD by an actuator using a piezo-electric element. SOLUTION: A 1st actuator for positioning a head 45 in the tracking direction is composed of a 1st piezo-electric element 12, a drive shaft 13, a slider 14, etc. A 2nd actuator for adjusting a gap between the recording medium and the head is arranged under the slider 14. The 2nd actuator is composed of a 2nd piezo-electric element 41 fixedly boned to the bottom face of the slider 14, a drive shaft 42, a slide arm 43, and the head 45 fixed to the slide arm and arranged close to the back face of the recording medium 21. The head 45 is positioned by applying saw-tooth wave driving pulses to the 1st and 2nd piezo-electric elements and driving the slide arm 43 at a high speed to move it to a prescribed position, then applying a prescribed voltage to the 1st and 2nd piezo-electric elements to precisely move the arm by a desired distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device using an electromechanical transducer, and in particular, to a nanometer (nm).
Suitable for driving components of precision equipment requiring high-precision driving at the resolution of the order, for example, driving in the tracking direction and focusing direction of the write / read head in an information recording apparatus using a high-density recording medium. The present invention relates to a driving device using an electromechanical conversion element.

[0002]

2. Description of the Related Art Hard disk drives (hereinafter referred to as HDDs) used in personal computers are increasingly required to be small and have a large capacity.
In order to increase the storage capacity of the recording medium, it is required to increase the track density and the linear recording density of the recording medium. In order to meet the demand for such a high recording density of the HDD, a technique for positioning the head with respect to a target track on a recording medium with high accuracy is required. Here, the head refers to a head that performs both writing and / or reading of information on a recording medium.

FIG. 18 is a view showing an example of the configuration of a currently proposed HDD head positioning mechanism. FIG.
8, reference numeral 101 denotes a recording medium, 102 denotes a rotating shaft of a spindle motor, 103 denotes a circuit board, and 104 denotes a flexible print card.

The head positioning mechanism includes a suspension 106 for supporting the head 105, a carriage 107 for supporting the suspension 106, an actuator using a voice coil motor (hereinafter referred to as VCM) for supporting and driving the carriage 107, and a piezoelectric element 111. Consists of the actuator used.

Reference numeral 108 denotes a rotating shaft of the carriage 107, and reference numeral 110 denotes a coil holding frame for holding the driving coil 109.

The VCM is an actuator composed of a drive coil 109 and a permanent magnet (not shown). The VCM causes the carriage 107 to rotate the rotary shaft 1 by the action of a magnetic field generated by the permanent magnet and an electromagnetic force caused by a current flowing through the drive coil 109.
Rotate around 08.

The piezoelectric element 111 constitutes an actuator which operates so as to compensate for high-frequency resonance when the VCM is driven. This actuator enables high-accuracy tracking with a track width of 1 μm or less.

[0008] The head 105 is a flying head that is configured to fly a predetermined minute distance from the surface of the recording medium 101 when the recording medium 101 rotates at a high speed. Writing and reading of information can be performed in the state.

The recording medium 101 is a spindle motor 102
To rotate at high speed. When the head 105 is positioned with respect to a specific track by the above-described head positioning mechanism, writing / reading of information is started. In the case of reading information, a read signal read from the recording medium 101 by the head 105 is input to a circuit board 103 on which a head amplifier and the like are mounted via a flexible print card 104, and is subjected to predetermined signal processing. Thereafter, the data is output to an information processing device such as a personal computer. Also, in the case of writing information, a write signal subjected to predetermined signal processing is supplied to the head 105 and written to the recording medium 101.

[0010]

As described above, in the conventional hard disk drive, an actuator using a voice coil motor for a head positioning mechanism and an actuator using a piezoelectric element in order to realize high-precision tracking of a head. Are used.
For this reason, it has been pointed out that the structure of the head positioning mechanism becomes complicated, and that disadvantages such as an increase in manufacturing cost and a decrease in reliability are found.

Also, an actuator using a voice coil motor has a low driving resolution, so that it is difficult to realize high-precision tracking of a head, and is not suitable for writing / reading information to / from an ultra-high-density recording medium. .

Further, if the head positioning mechanism is constituted only by an actuator using a voice coil motor in order to simplify the head positioning mechanism, it becomes difficult to perform high-accuracy tracking due to the influence of high-frequency resonance generated in the driving mechanism. There are inconveniences. An object of the present invention is to solve these problems.

[0013]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and an invention according to claim 1 includes an information recording medium, a head for writing / reading information to / from the information recording medium, and an electric head. A first actuator including a mechanical conversion element, a driving member fixedly connected to the electromechanical conversion element, and a moving member fixedly connected to the head and frictionally connected to the driving member; and the first actuator. A coarse movement mode drive circuit for applying a sawtooth drive pulse to the electromechanical transducer element, a fine motion mode drive circuit for applying a predetermined voltage to the electromechanical transducer element of the first actuator, and a control circuit, The control circuit selectively operates the coarse mode drive circuit and the fine mode drive circuit based on the information indicating the information recording area on the information recording medium detected by the head, and controls the first mode. Driving the actuator, and controlling so as to maintain the position of the head appropriate for writing / reading information into desired information recording area of the information recording medium.

According to a second aspect of the present invention, there is provided an information recording medium, a head for writing / reading information to / from the information recording medium, an electromechanical transducer, and a driving member fixedly connected to the electromechanical transducer. A second actuator having a head fixedly coupled to the driving member and frictionally coupled to the driving member; and a coarse motion mode for applying a sawtooth driving pulse to an electromechanical transducer of the second actuator. A drive circuit, a fine movement mode drive circuit for applying a predetermined voltage to the electromechanical transducer of the second actuator, and a control circuit, wherein the control circuit is configured to control a distance between the information recording medium detected by the head and the head. Selectively driving the coarse movement mode drive circuit and the fine movement mode drive circuit based on the information indicating the second actuator to drive the second actuator. And controlling so as to maintain a desired spacing Te.

According to a third aspect of the present invention, there is provided an information recording medium, a head for writing / reading information to / from the information recording medium, a first electromechanical transducer, and fixedly coupled to the electromechanical transducer. A first actuator comprising a driving member, a moving member fixedly coupled to the head and frictionally coupled to the driving member, and applying a sawtooth driving pulse to the electromechanical transducer of the first actuator. First
A coarse movement mode drive circuit, a first fine movement mode drive circuit for applying a predetermined voltage to the electromechanical transducer of the first actuator, a second electromechanical transducer, and a stuck to the electromechanical transducer. A second actuator comprising a coupled driving member, a moving member to which the head is fixedly coupled and frictionally coupled to the driving member, and a sawtooth drive pulse applied to the electromechanical transducer of the second actuator. A second coarse movement mode driving circuit for applying a voltage, a second fine movement mode driving circuit for applying a predetermined voltage to the electromechanical transducer of the second actuator, and a control circuit, wherein the control circuit comprises: Selectively activates the first coarse mode drive circuit and the first fine mode drive circuit based on the information indicating the information recording area on the desired information recording medium detected by the first actuation. And controlling the head to maintain a position suitable for writing / reading information to / from the information recording medium, and controlling the head based on the information indicating the distance between the information recording medium and the head detected by the head. A second coarse movement mode drive circuit and a second fine movement mode drive circuit are selectively operated to drive the second actuator and control the head to maintain a desired distance from the information recording medium. It is characterized by the following.

The information recording medium is an information recording medium constituted by a rotating disk, and a driving direction of a head by the first actuator is parallel to an information recording surface of the rotating disk constituting the information recording medium. The driving direction of the head by the second actuator is a direction perpendicular to the information recording surface of the rotating disk constituting the information recording medium.

[0017]

Embodiments of the present invention will be described below. First, the configuration of an actuator using a piezoelectric element, which is one of the electromechanical transducers, will be described.

FIGS. 1 and 2 show an example of a straight type actuator using a piezoelectric element. FIG. 1 is a perspective view showing an exploded state, and FIG. 2 is a perspective view showing an assembled state. The actuator 10 includes a piezoelectric element 2, a drive shaft 3, a slider 4, a frame 1, and the like, and a driven member (not shown) is coupled to the slider 4.

The frame 1 has a substantially cylindrical shape, and one end 1a of the frame 1 is a portion to be attached to a device (not shown). The frame 1 has a hole 1b for accommodating the piezoelectric element 2 and a hole 1c for accommodating the slider 4, and the hole 1b and the hole 1b are formed.
c, a partition plate 1g, and a hole 1c of the frame 1
An end plate 1h is also formed at the side end.

The piezoelectric element 2 is housed in the hole 1 b of the frame 1, one end of which is adhesively fixed to one wall surface 1 f of the hole 1 b of the frame 1, and the other end is adhesively fixed to the end 3 a of the drive shaft 3. Is done.

The drive shaft 3 is supported movably in the axial direction by a bearing hole 1d provided in the partition plate 1g of the frame 1 and a bearing hole 1e provided in the end plate 1h, and is driven by expansion and contraction of the piezoelectric element 2 in the thickness direction. The shaft 3 reciprocates in the axial direction. Drive shaft 3
Is mounted with a slider 4 described below.

The slider 4 has a main body 4a that comes into frictional contact with the drive shaft 3 and a mounting portion 4 that fixes a driven member (not shown) (for example, a head in the above-described head positioning mechanism).
e. A cutout 4b is formed in the center of the main body 4a, and holes 4d through which the drive shaft 3 penetrates are provided in the left and right wall portions of the cutout 4b. The notch 4b is formed with a groove 4c having a semicircular cross-section and in contact with a substantially lower half of the drive shaft 3. The mounting portion 4e is provided with a mounting hole 4f on its lower surface through which a screw for mounting the driven member penetrates.

A pad 5 that comes into contact with the drive shaft 3 penetrating through the hole 4d from above is inserted into the notch 4b, and a lower half of the pad 5 is in contact with a substantially upper half of the drive shaft 3 in cross section. A circular groove 5a is formed. The pad 5 is configured to fit into the left and right wall surfaces of the cutout portion 4b without looseness.

The pad 5 is pressed against the drive shaft 3 by a leaf spring 6 fixed to the main body 4a of the slider 4 with a screw 8, and frictionally coupled with the pad 5. The pressing force is adjusted by tightening or reducing the screw 8. can do.

FIG. 3 is a sectional view showing the structure of the frictional connection between the drive shaft 3, the main body 4a of the slider 4 and the pad 5, and a notch 4b formed in the main body 4a of the slider 4. The pad 5 is inserted into the. A ridge 5a provided on the upper surface of the pad 5 is pressed downward by a leaf spring 6 fixed to the main body 4a with a screw 8, and the pad 5 is
Frictional coupling with an appropriate pressing force.

The actuator can be driven in two modes, a fine movement mode and a coarse movement mode. The fine movement mode is a drive mode suitable for precisely positioning the driven member, and the coarse movement mode is a drive mode suitable for quickly moving the driven member.

FIGS. 4A and 4B show the voltage applied to the piezoelectric element and the amount of displacement of the slider in the fine movement mode. The horizontal axis represents time, and the vertical axis represents applied voltage and the amount of displacement.

In the fine movement mode, when a voltage corresponding to a predetermined distance to be moved is applied to the piezoelectric element 2, an expansion displacement or a contraction displacement corresponding to the applied voltage occurs in the piezoelectric element 2, and the piezoelectric element 2 is joined to the piezoelectric element 2. The driving shaft 3 moves in a predetermined direction by a predetermined distance. At this time, since the slider 4 frictionally connected to the drive shaft 3 moves integrally with the drive shaft 3, the driven member connected to the slider 4 can also be moved by a predetermined distance in a predetermined direction.

That is, when the magnitude of the applied voltage changes as shown in FIG. 4A, the amount of displacement of the slider changes as shown in FIG. 4B, and the magnitude of the applied voltage and the displacement of the slider change. It can be seen that the amount is substantially proportional, and that the minute displacement can be adjusted by adjusting the applied voltage.

FIGS. 5A and 5B are diagrams showing the sawtooth waveform drive pulse voltage applied to the piezoelectric element and the amount of displacement of the slider in the coarse movement mode, in which the horizontal axis represents time and the vertical axis represents applied voltage. The voltage and the displacement are shown.

In the coarse movement mode, a driving pulse having a sawtooth waveform composed of a gentle rising portion and a rapid falling portion as shown in FIG. 5A is applied to the piezoelectric element 2. At a gentle rising portion of the drive pulse, the piezoelectric element 2 gradually expands in the thickness direction, and the drive shaft 3 is axially displaced in the direction of arrow a. For this reason, the slider 4 frictionally coupled to the drive shaft 3 also moves in the direction of arrow a, so that the driven member coupled to the slider 4 can be moved in the direction of arrow a.

At the rapid falling portion of the drive pulse, the piezoelectric element 2 rapidly contracts in the thickness direction, and the drive shaft 3 is also displaced in the axial direction in the direction opposite to the arrow a. At this time, the slider 4 frictionally coupled to the drive shaft 3 overcomes the frictional coupling force between the slider 4 and the drive shaft 3 due to its inertia force and substantially stays at that position and does not move.

Here, "substantially" means that in both the direction of arrow "a" and the direction opposite thereto, those that follow and follow the slide between the slider 4 and the drive shaft 3 are included. The slider 4 moves in the direction of arrow a as a whole due to the difference in driving time of the piezoelectric element 2 due to the driving pulse.

That is, when a driving pulse as shown in FIG. 5A is repeatedly and continuously applied to the piezoelectric element, the displacement of the slider gradually accumulates and increases as shown in FIG. 5B. It can be moved in the direction indicated by arrow a.

The movement of the slider in the direction opposite to the arrow a can be achieved by applying a drive pulse having a waveform having a rapid rising portion and a gentle falling portion to the piezoelectric element.

[First Embodiment] Next, a head positioning mechanism using an actuator using the above-described piezoelectric element will be described.

FIGS. 6 and 7 are views for explaining the head positioning mechanism of the first embodiment. FIG. 6 is a perspective view of the head positioning mechanism, and FIG. 7 is a cross-sectional view along the drive shaft.
6 and 7, reference numeral 11 denotes a frame, and reference numeral 21 denotes a disc-shaped recording medium, which is driven by a drive shaft 22 driven by a spindle motor 23 disposed below the frame 11. Here, the lower surface (back surface) of the recording medium 21 is used as an information recording area.

The actuator constituting the head positioning mechanism has substantially the same configuration as that described with reference to FIGS. The piezoelectric element 12 is housed in a hole 11a formed in the frame, one end of which is adhesively fixed to one wall surface 11b of the hole 11a, and the other end is adhesively fixed to an end 13a of the drive shaft 13.

The drive shaft 13 is movably supported in the axial direction by a bearing hole 11d provided in a partition plate 11c formed in the frame and a bearing hole 11f provided in the frame 11, and is driven by expansion and contraction of the piezoelectric element 12 in the thickness direction. The drive shaft 13 reciprocates in the axial direction. The drive shaft 13 has a notched flat portion 13b formed over its entire length in the axial direction.
Engagement with a rotation restricting member (not shown) formed at d and 11f restricts rotation around the axis.

The slider 14 has a main body 14a that comes into frictional contact with the drive shaft 13, and a mounting portion 14e that fixes an arm 18 having a head 20 for writing / reading information to / from a recording medium 21 at the tip. . Arm 18 is a small screw 1
9, the slider 14 is fixed to the mounting portion 14e of the slider 14.

A notch 14b is formed in the center of the body 14a of the slider 14, and holes 14 through which the drive shaft 13 passes are formed in the left and right wall portions of the notch 14b.
d is provided. Further, a groove having a semicircular cross section that is in contact with a substantially lower half of the drive shaft 13 is formed in the cutout portion 14b.

A pad 15 that comes into contact with the drive shaft 13 penetrating the hole 14d from above is inserted into the cutout portion 14b. A circular groove is formed. Pad 15
Are configured to fit into the left and right wall surfaces of the cutout portion 14b without looseness.

The pad 15 is pressed against the drive shaft 13 by a leaf spring 16 fixed to the main body portion 14a of the slider 14 with a small screw 17, and is frictionally coupled. Can be adjusted.

The head 20 for writing / reading information to / from the recording medium 21 is fixedly mounted on the tip of the arm 18. The head 20 has a configuration called a flying head, and is arranged close to the lower surface (back surface) of the recording medium 21. When the recording medium 21 rotates, the air pressure generated on the surface of the recording medium by the rotation is reduced. As a result, information is written / read to / from the recording medium 21 in a non-contact state while slightly floating above and away from the recording medium 21. In addition,
The head 20 includes an information writing head unit and an information reading head unit. Here, the head 20 that performs writing / reading of information will be described.

FIG. 8 is a block diagram showing the configuration of the control circuit 30 of the head positioning mechanism according to the first embodiment.
The control circuit 30 is configured with a CPU 31 at the center.
A track detection circuit 32, a data demodulation circuit 33, and a data modulation circuit 34 are connected to the input / output port of U31.
A tracking coarse movement circuit 37 and a tracking fine movement circuit 38 are connected to an output port of the CPU 31.

The information recorded on the recording medium 21 is read by the head 20, and the read signal is subjected to signal processing by a recording signal detection circuit 35, and then input to a track detection circuit 32 and a data demodulation circuit 33, respectively. .

The data demodulation circuit 33 extracts recording data from the detection signal, demodulates the data, and outputs the demodulated data to a personal computer or the like. The data modulation circuit 34 modulates data output from a personal computer or the like, outputs the data to the head 20 via the signal recording circuit 36, and records the data on the recording medium 21.

Next, the tracking operation of the head 20 by the control circuit 30 will be described. A signal (detection signal) read by the head 20 is signal-processed by a recording signal detection circuit 35 and then processed by a track detection circuit 32 to separate track information such as a track number and output to the CPU 31. The CPU 31 analyzes the track information and determines whether a desired track has been detected.

As a result of the determination, if the desired track is not detected, it means that the head 20 is not at the desired track position. Therefore, the CPU 31 activates the tracking coarse movement circuit 37 to set the piezoelectric element 12 in the coarse movement mode. And the head 20 is moved at a high speed toward a desired track. At this time, the driving direction of the probe, that is, the waveform of the driving pulse (whether the waveform has a gentle rising portion and a rapid falling portion,
The opposite waveform is determined.

In the seek operation, analysis and determination of track information of a signal (detection signal) read by the head 20 and feedback control of the seek operation based on the determination result are repeated until a desired track is detected.

As a result of the determination, if a desired track is detected, it means that the head 20 has reached a desired track position.
7 to the tracking fine movement circuit 38, and the piezoelectric element 1
2 performs a tracking operation for driving in the fine movement mode,
Feedback control is performed so that the head 20 accurately follows the detected desired track.

In the conventional head positioning mechanism, two actuators, an actuator using a voice coil motor and an actuator using a piezoelectric element, are required to move and precisely position the head. According to the first embodiment, the movement and precise positioning of the head can be easily realized with only one actuator using a piezoelectric element.

[Second Embodiment] FIG. 9 is a perspective view for explaining a head positioning mechanism according to a second embodiment.
The head positioning mechanism according to the second embodiment includes a first actuator and a second actuator, the first actuator constituting a head positioning mechanism in a tracking direction, and the second actuator comprising a head and a recording medium. And a mechanism for adjusting the interval between them.

In the head positioning mechanism of the first embodiment, the head 20 is a flying head that flies by the rotation of the recording medium 21 and the distance between the head 20 and the recording medium 21 cannot be adjusted. According to the second embodiment, the distance between the head and the recording medium can be freely adjusted.

In FIG. 9, reference numeral 11 denotes a frame, 21 denotes a recording medium, and a drive shaft 22 driven by a spindle motor (not shown) disposed below the frame 11.
Driven by Here, the lower surface (back surface) of the recording medium 21 is used as an information recording area.

The first actuator constituting the head positioning mechanism in the tracking direction is the same as that of the first embodiment, and the first piezoelectric element 12, the drive shaft 13,
It is composed of a slider 14, a pad 15, a leaf spring 16, and the like. Since the configuration of this portion is the same as that of the actuator head positioning mechanism of the first embodiment, the same components are denoted by the same reference numerals, and detailed description is omitted.

On the lower surface of the slider 14, a second actuator for adjusting the distance between the head 45 and the recording medium 21 is arranged. Hereinafter, the configuration of the second actuator will be described.

The second piezoelectric element 4 is provided on the lower surface of the slider 14.
1 is adhesively fixed, and a second drive shaft 42 is adhesively fixed to the lower surface of the second piezoelectric element 41. A slide arm 43 is fitted and frictionally coupled to the second drive shaft 42. The recording medium 2 is attached to one end of the slide arm 43.
A support body 44 having a head 45 for writing / reading information to / from the head 1 is fixed. The head 45 is located close to the lower surface (back surface) of the recording medium 21.

The adjustment of the distance between the head 45 and the recording medium 21 by the second actuator, which is referred to as focus adjustment. The focus adjustment is an interval indicating the distance between the head 45 and the recording medium 21 detected by a unit described later. The second piezoelectric element 41 is driven in the coarse movement mode and the fine movement mode based on the information, and the distance is adjusted by moving the second drive shaft 42 and the slide arm 43 in the height direction (vertical direction in FIG. 9). I do. Thereby, the interval between the head 45 and the recording medium 21 can be adjusted with high accuracy that cannot be achieved by the flying head.

The interval information indicating the distance between the head 45 and the recording medium 21 is described in, for example, Japanese Unexamined Patent Application Publication No.
It can be detected by the means disclosed in Japanese Patent No. 65418. That is, paying attention to the fact that the capacitance of a capacitor formed by two conductors disposed opposite to each other is inversely proportional to the distance between the two conductors, a conductor (not shown) is provided on both the recording medium 21 and the head 45. By providing a layer and detecting a change in capacitance between the layers, distance information indicating the distance between the head 45 and the recording medium 21 can be obtained.

The tracking operation for positioning the head in the tracking direction is the same as that of the first embodiment. That is, in a seek operation for quickly moving the head 45 to a desired recording area of the recording medium, the first actuator is driven in the coarse movement mode to move the head 45 toward a desired track at a high speed by a predetermined distance. . After arriving at the desired track, the mode is switched to the fine movement mode to perform the following operation, and the head 45 is controlled so as to precisely follow the track.

FIG. 10 is a block diagram showing the configuration of the control circuit 50 of the head positioning mechanism according to the second embodiment. In this figure, a head positioning mechanism is shown in a front view and a side view in order to explain the tracking operation and the focus adjustment of the head.

The control circuit 50 is composed mainly of a CPU 51, and an input / output port of the CPU 51 is connected to a track detection circuit 52, a data demodulation circuit 53, an interval detection circuit 54, and a data modulation circuit 55. The output port of the CPU 51 is connected to a focus coarse movement circuit 61, a focus fine movement circuit 62, a tracking coarse movement circuit 63, and a tracking fine movement circuit 64.

The information recorded on the recording medium 21 is read by the head 45, subjected to signal processing by a recording signal detection circuit 56, and then input to a track detection circuit 52 and a data demodulation circuit 53, respectively.

The data demodulation circuit 53 extracts recording data from the detection signal, demodulates the data, and outputs the demodulated data to a personal computer or the like. The data modulation circuit 55 modulates data output from a personal computer or the like, outputs the data to the head 45 via the signal recording circuit 57, and records the data on the recording medium 21.

Next, the tracking operation of the head 45 by the control circuit 50 will be described. A signal (detection signal) read by the head 45 is signal-processed by a recording signal detection circuit 56, and then processed by a track detection circuit 52 to separate track information such as a track number and output to the CPU 51. The CPU 51 analyzes the track information and determines whether a desired track has been detected.

As a result of the determination, if the desired track is not detected, it means that the head 45 is not at the desired track position. Therefore, the CPU 51 activates the tracking coarse movement circuit 63 to set the piezoelectric element 12 in the coarse movement mode. , The head 45 is moved at high speed toward a desired track. At this time, the driving direction of the probe, that is, the waveform of the driving pulse (whether the waveform has a gentle rising portion and a rapid falling portion,
The opposite waveform is determined.

In the seek operation, analysis and determination of track information of a signal (detection signal) read by the head 45 and feedback control of the seek operation based on the determination result are repeated until a desired track is detected.

As a result of the determination, when a desired track is detected, it means that the head 45 has reached a desired track position.
3 to the tracking fine movement circuit 64, and the piezoelectric element 1
2 performs a tracking operation for driving in the fine movement mode,
Feedback control is performed so that the head 45 accurately follows the detected desired track.

Next, the operation of the control circuit 50 for controlling the distance between the head 45 and the recording medium 21 by the second actuator will be described. As described above, the head 45
Information (interval information) indicating the interval d between the recording medium 21 and
It is assumed that the information is obtained based on information indicating a change in capacitance between conductor layers (not shown) provided on both the recording medium 21 and the head 45 and is input to the CPU 51.

Hereinafter, the interval control operation executed by the CPU 51 will be described with reference to a flowchart shown in FIG.

Here, as an example, the second piezoelectric element 41
Is 10 μm when the applied voltage Vd is 150 V, and the operating range of the focus fine movement circuit 62 is 5 μm, which is の of the maximum displacement of the second piezoelectric element 41. The operating range of the focus fine movement circuit 62 is 5 μm.
It is assumed that the value is set to a value sufficiently larger than the permissible error range of the run-out in the height direction at the time of one rotation.

First, a distance d between the head 45 and the recording medium 21 is set to a preset limit distance dm (5 in this example).
μm) is determined (step P1).
If the interval exceeds the limit interval, the focus coarse movement circuit 61 is operated to drive the second piezoelectric element 41 in the coarse movement mode (step P2), and after the drive for a predetermined time (step P2).
Return to 1). When the interval d is determined to be equal to or smaller than the preset limit interval dm (5 μm in this example) in the judgment of step P1, the focus fine movement circuit 62 is operated to drive the second piezoelectric element 41 in the fine movement mode (step P1). P3) The feedback control is performed such that the predetermined interval d0 is precisely maintained by directing the head 45 toward the recording medium 21.

The applied voltage Vd to the second piezoelectric element 41 is determined, and the applied voltage Vd is 0 V or more and 150 V or less (0 V <Vd
If it is within the range of <150 V), the feedback control of step P3 is continued. When the applied voltage Vd is 0 V
Below, or in the case of 150 V or more, it is determined that the operation has deviated from the operation range of the fine movement mode for some reason, and the process returns to step P2 to determine the drive in the coarse movement mode and the distance d. Limit interval dm (in this example,
5 μm), and waits for the interval d to be equal to or less than a preset limit interval dm before shifting to the fine movement mode.

FIG. 12 shows the temporal change of the voltage Vd applied to the second piezoelectric element 41 when the above-described second piezoelectric element 41 is driven in the coarse movement mode and the fine movement mode.
FIG. 12A shows a temporal change in the distance d between the recording medium 21 and the recording medium 21. FIG. 12A shows that the drive pulse is applied in the coarse movement mode, and after a predetermined time, the mode is switched to the fine movement mode to change the voltage Vd.
5 shows a temporal change of the voltage Vd when is applied. Also,
FIG. 12B shows a temporal change in the interval between the head 45 and the recording medium 21. A line (H) indicates the displacement of the head 45, and a line (D) indicates the displacement of the recording medium 21.

As is clear from FIG. 12, in the coarse movement mode, the distance d between the head 45 and the recording medium 21 rapidly approaches, and when the mode is shifted to the fine movement mode, a swing in the height direction occurs when the recording medium 21 rotates. However, it can be seen that the head 45 follows the recording medium 21 while maintaining the interval d.

The head positioning mechanisms according to the first and second embodiments of the present invention have been described above. These head positioning mechanisms include a magnetic recording type recording medium and an optical recording type recording medium. The present invention can be applied to any type of recording medium such as a recording medium and a magneto-optical recording medium.

Further, the configuration of the first and second embodiments of the present invention is not limited to the head positioning mechanism. For example, a probe or the like can be moved at a high speed to a specific portion of the object to be inspected. Needless to say, the present invention can be applied to a mechanism for precisely positioning.

[Third Embodiment] FIG. 13 is a perspective view for explaining a head positioning mechanism according to a third embodiment. The head positioning mechanism according to the third embodiment is the same as the head positioning mechanism according to the second embodiment, except that the second actuator used for adjusting the distance between the head and the recording medium, that is, for adjusting the focus, is provided with a torsional piezoelectric actuator. An element is used. Also with this actuator, the distance between the head and the recording medium can be freely adjusted as in the second embodiment.

In FIG. 13, reference numeral 11 denotes a frame, 21 denotes a recording medium, and a drive shaft 2 driven by a spindle motor (not shown) disposed below the frame 11.
2 driven. Here, the lower surface (back surface) of the recording medium 21 is used as an information recording area.

The first actuator constituting the positioning mechanism of the head in the tracking direction is the same as that of the first and second embodiments, and includes a first piezoelectric element 12, a drive shaft 13, a slider 14, a pad 15, a leaf spring 16 and the like. Since the configuration of this portion is the same as the actuator positioning mechanism of the first and second embodiments, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

On the side surface of the slider 14, a second actuator 70 using a torsion type piezoelectric element for adjusting the distance between the head 75 and the recording medium 21, ie, adjusting the focus.
The head 75 is attached to the second actuator 70, and is disposed close to the lower surface of the recording medium 21.

The configuration of the second actuator will be described. FIG. 14 is a perspective view illustrating the configuration of the second actuator 70, FIG. 15 is a cross-sectional view thereof, and FIG. 16 is a side view of the head side thereof.

14 to 16, reference numeral 71 denotes a fixed portion, and reference numeral 72 denotes a torsion type piezoelectric element (hereinafter, simply referred to as a piezoelectric element), which has a substantially cylindrical shape as a whole. When a voltage is applied between the electrodes that are not present, a twist occurs around the cylindrical axis.

One end of the piezoelectric element 72 is adhered and fixed to the fixing portion 71, and the other end, that is, the free end, is in frictional contact with the rotary friction portion 73. That is, as shown in the cross-sectional view of FIG. 15, a spring 76 attached to a shaft 77 having one end fixed to the fixed portion 71 is provided with a disk 76 loosely fitted to the shaft 77.
15, the bearing 78 disposed at the center of the rotating friction portion 73 is pressed leftward in FIG. 15, so that the rotating friction portion 73 comes into frictional contact with the end face of the free end of the piezoelectric element 72 with an appropriate frictional force. I do. The magnitude of the frictional force can be adjusted by changing the position of the nut 76b engaged with the shaft 77 to increase or decrease the urging force of the spring 76.

An arm 74 is fixed to the rotating friction portion 73, and a head 75 is attached to the arm 74. When a slowly changing voltage is applied to the electrodes of the piezoelectric element 72, the piezoelectric element 72 is twisted around the cylindrical axis,
The rotating friction portion 73 that comes into frictional contact with the end surface of the free end rotates around the cylindrical axis together with the torsion of the piezoelectric element 72 without causing slip on the contact surface.

When the voltage applied to the electrodes of the piezoelectric element 72 is suddenly changed, the piezoelectric element 72 is twisted around the cylindrical axis. The inertial force acts and the inertial force overcomes the frictional force, so that a slip occurs on the contact surface, and the rotating friction portion 73 remains substantially at that position.

FIG. 17 is a perspective view for explaining an actuator operation using a torsion type piezoelectric element, and FIG. 17 (a) shows a state in which no twist is generated in the piezoelectric element. FIG. 7B shows a state in which a slowly changing voltage is applied to the piezoelectric element to generate a torsional rotation in the clockwise direction, and the rotational friction portion 73 rotates together with the torsion of the piezoelectric element. FIG. 8C shows a case where the voltage applied to the piezoelectric element is rapidly changed (cut off) from the state shown in FIG. 8B, and the torsion of the piezoelectric element has been eliminated. This shows a state of staying at that position.

The torsional piezoelectric element can be driven in the coarse movement mode and the fine movement mode. In the coarse motion mode, a saw-tooth wave driving pulse is applied to the piezoelectric element 72 to generate reciprocating torsional vibrations having different torsional speeds on the piezoelectric element 72, and the rotating friction portion 73 that comes into frictional contact with the piezoelectric element 72 rotates around the cylindrical axis. Rotation motion can be given. In the fine movement mode, a voltage can be applied to the piezoelectric element 72 to cause the piezoelectric element 72 to generate a torsional displacement around a cylindrical axis.

Head 75 by second actuator 70
The adjustment of the distance between the image and the recording medium 21, that is, the focus adjustment will be described. First, the detected distance information d indicating the distance between the head 75 and the recording medium 21 is stored in both the recording medium 21 and the head 75 in the same manner as described in the description of the second embodiment. The distance information d can be obtained by providing a conductor layer (not shown) and detecting a change in capacitance between them.

The focus adjustment is based on the detected interval information d.
Based on the above, the rotary friction portion 73 is rotated by driving the second actuator 70 in the coarse movement mode and in the fine movement mode, and adjusts the distance between the head 75 and the recording medium 21.
Thereby, the interval between the head 75 and the recording medium 21 can be adjusted with high accuracy.

The tracking operation for positioning the head in the tracking direction is the same as that of the first and second embodiments. That is, in the seek operation for quickly moving the head 75 to a desired recording area of the recording medium, the first actuator is driven in the coarse movement mode to move the head 75 toward a desired track at a high speed by a predetermined distance. . After reaching the desired track, the mode is switched to the fine movement mode to perform the following operation, and the head 75 is controlled so as to precisely follow the track.

The configuration of the control circuit of the head positioning mechanism of the third embodiment and the tracking operation of the head 75 by the CPU constituting the control circuit are the same as those of the second embodiment. Description is omitted. Also,
The operation of controlling the distance between the head 75 and the recording medium 21 by the second actuator is the same as that in the second embodiment, and a description thereof will be omitted.

However, in the second embodiment, the head 45 moves in the direction substantially perpendicular to the recording medium 21 to control the interval, whereas in the third embodiment, the head 45 The difference is that the distance control is performed by moving the recording medium 75 in an arc with respect to the recording medium 21. Further, the head positioning mechanism according to the third embodiment has a shorter dimension in the vertical direction (vertical direction in FIGS. 9 and 13) than the head positioning mechanism according to the second embodiment, and is compact as a whole. I'm sorry. Hereinafter, the effect of the head 75 moving in a circular arc with respect to the recording medium 21 will be discussed.

The inclination angle of the head 75 with respect to the recording medium 21 is the closest point of focus, that is, the head 75 and the recording medium 21.
It is sufficient that the inclination angle when the interval between the above and the optimum value is equal to or smaller than the allowable value. Now, it is assumed that the inclination angle at the focus closest point is set to zero (0) at the beginning of assembly. When the angle at which the head 75 moves away from the closest focus point and reaches the furthest focus point is calculated, the distance from the closest focus point to the farthest focus point is 5 μm.
m, the distance (radius) from the rotation axis of the head 75 attached to the rotating friction portion 73 is 5 mm, the tilt angle of the head 75 at the farthest point of focus is 1/1000 radian, and the angle is 0.1 mm. 06 degrees, which is in a sufficiently acceptable range.

The head positioning mechanisms according to the first to third embodiments of the present invention have been described above. These head positioning mechanisms include optical recording type recording media and magneto-optical recording type recording media. For example, the present invention can be applied to any type of recording medium head positioning mechanism.

Furthermore, the configuration of the first to third embodiments of the present invention is not limited to the head positioning mechanism. For example, a probe or the like can be moved at a high speed with respect to a specific portion of an object to be inspected. Needless to say, the present invention can be applied to a mechanism for precisely positioning.

[0098]

As described above, according to the present invention, the movement and positioning of the members of precision equipment can be easily realized only by the actuator using the electromechanical transducer.
The configuration of the positioning mechanism can be simplified, the manufacturing cost does not increase, and the reliability does not decrease.

Further, since the actuator using the electromechanical transducer has a higher driving resolution than the actuator using the voice coil, the movement and positioning of the members of the precision equipment can be realized with high accuracy. For example, if the present invention is applied to highly accurate tracking and positioning of a head of an information recording apparatus, a head positioning mechanism suitable for writing / reading information to / from an ultra-high-density recording medium can be configured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a disassembled state of a linear actuator using a piezoelectric element.

FIG. 2 is a perspective view showing an assembled state of the actuator shown in FIG. 1;

FIG. 3 is a cross-sectional view showing a configuration of a friction coupling portion of the actuator shown in FIG. 1;

FIG. 4 is a diagram illustrating a voltage applied to a piezoelectric element and a displacement amount of a slider (a driven member).

FIG. 5 is a diagram for explaining a drive pulse voltage having a sawtooth waveform applied to a piezoelectric element and a displacement amount of a slider (a driven member).

FIG. 6 is a perspective view illustrating a head positioning mechanism according to the first embodiment.

FIG. 7 is a sectional view taken along a drive shaft of the head positioning mechanism shown in FIG. 6;

FIG. 8 is a block diagram illustrating a control circuit of the head positioning mechanism according to the first embodiment.

FIG. 9 is a perspective view illustrating a head positioning mechanism according to a second embodiment.

FIG. 10 is a block diagram showing a control circuit of a head positioning mechanism according to a second embodiment.

FIG. 11 is a flowchart showing an interval control operation by the interval detection circuit.

FIG. 12 is a diagram showing a temporal change of a voltage applied to the piezoelectric element and a temporal change of an interval between a head and a recording medium when a second piezoelectric element is driven in a coarse movement mode and a fine movement mode.

FIG. 13 is a perspective view illustrating a head positioning mechanism according to a third embodiment.

FIG. 14 is a perspective view illustrating the configuration of an actuator according to a third embodiment.

FIG. 15 is a sectional view of the actuator shown in FIG. 14;

16 is a side view of the actuator shown in FIG. 14 on the head side.

FIG. 17 is a perspective view illustrating the operation of the actuator shown in FIG. 14;

FIG. 18 is a diagram showing an example of a configuration of a conventional HDD head positioning mechanism.

[Explanation of symbols]

 Reference Signs List 1 frame 2 piezoelectric element 3 drive shaft 4 slider 5 pad 6 leaf spring 10 actuator 11 frame 12 piezoelectric element 13 drive shaft 14 slider 18 arm 20 head 21 recording medium 22 drive shaft 23 spindle motor 30 control circuit 31 CPU 32 track detection circuit 33 Data demodulation circuit 34 Data modulation circuit 35 Recording signal detection circuit 36 Signal recording circuit 37 Tracking coarse movement circuit 38 Tracking fine movement circuit 41 Second piezoelectric element 42 Second drive shaft 43 Slide arm 44 Support body 45 Head 50 Control circuit 51 CPU 52 Track detection circuit 53 Data demodulation circuit 54 Interval detection circuit 55 Data modulation circuit 56 Recording signal detection circuit 57 Signal recording circuit 61 Focus coarse movement circuit 62 Focus fine movement circuit 63 Tracking coarse movement circuit 6 4 Tracking Fine Motion Circuit 70 Actuator 72 Torsion Type Piezoelectric Element 73 Rotary Friction Unit 74 Arm 75 Head 76 Spring

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02N 2/00 H02N 2/00 C 5H680 // G01N 13/10 G01N 13/10 C G11B 7/09 G11B 7 / 09 A 11/105 556 11/105 556D 556A (72) Ryuichi Yoshida 2-3-1-13 Azuchicho, Chuo-ku, Osaka City, Osaka Prefecture Inside the Osaka International Building Minolta Co., Ltd. (72) Inventor Takayuki Hirano Osaka 2-13-13 Azuchi-cho, Chuo-ku, Osaka F-term in Osaka International Building Minolta Co., Ltd. 5D042 LA01 MA02 MA15 5D068 AA01 BB01 CC01 CC07 EE07 GG24 GG25 5D075 AA03 AA08 CE03 CE04 CE09 CE12 CE15 CE20 5D117 AA02 GG01GG03 JJ05 JJ07 5D118 AA03 AA13 BA01 BB02 BF12 CA14 EA14 5H680 AA00 AA04 AA08 BB04 BB13 BB16 BC00 BC10 CC03 DD01 DD23 DD27 DD37 DD53 DD66 DD67 DD73 DD83 DD88 DD92 DD95 EE07 EE22 FF04 FF24 FF30 FF32 FF38

Claims (5)

[Claims] An information recording medium; a head for writing / reading information to / from the information recording medium; an electromechanical transducer; a driving member fixedly coupled to the electromechanical transducer; A first actuator comprising a moving member fixedly coupled and frictionally coupled to the driving member; a coarse mode driving circuit for applying a sawtooth driving pulse to an electromechanical transducer of the first actuator; A fine movement mode drive circuit for applying a predetermined voltage to the electromechanical transducer of the first actuator; and a control circuit, wherein the control circuit is configured to perform a control based on information indicating an information recording area on the information recording medium detected by the head. And selectively operating the coarse movement mode drive circuit and the fine movement mode drive circuit to drive the first actuator, and the head is driven by a desired information recording area of an information recording medium. A driving device using an electromechanical transducer, wherein the driving device controls to maintain a position suitable for writing / reading information to / from a region. 2. An information recording medium, a head for writing / reading information to / from the information recording medium, an electromechanical transducer, a driving member fixedly coupled to the electromechanical transducer, and the head A second actuator fixedly coupled to the driving member and frictionally coupled to the driving member; a coarse mode driving circuit for applying a sawtooth driving pulse to an electromechanical transducer of the second actuator; A fine-motion mode drive circuit for applying a predetermined voltage to the electromechanical transducer of the second actuator; and a control circuit, wherein the control circuit is configured to detect a distance between the information recording medium and the head detected by the head. And selectively driving the coarse movement mode drive circuit and the fine movement mode drive circuit to drive the second actuator, so that the head moves at a desired distance from the information recording medium. A driving device using an electromechanical transducer, wherein the driving device is controlled to maintain the driving force. 3. An information recording medium, a head for writing / reading information to / from the information recording medium, a first electromechanical transducer, and a driving member fixedly coupled to the electromechanical transducer, A first actuator comprising a moving member fixedly coupled to the driving member and frictionally coupled to the driving member; and a first coarse motion for applying a sawtooth driving pulse to an electromechanical transducer of the first actuator. A mode drive circuit, a first fine movement mode drive circuit for applying a predetermined voltage to the electromechanical transducer of the first actuator, a second electromechanical transducer, and a fixedly coupled to the electromechanical transducer. A second actuator comprising a driving member, and a moving member to which the head is fixedly coupled and frictionally coupled to the driving member; and a saw-toothed electromechanical conversion element of the second actuator. A second coarse motion mode drive circuit for applying a waveform drive pulse, a second fine motion mode drive circuit for applying a predetermined voltage to the electromechanical transducer of the second actuator, and a control circuit. The circuit selectively activates the first coarse movement mode drive circuit and the first fine movement mode drive circuit based on information indicating an information recording area on a desired information recording medium detected by the head. 1 is driven to control the head to maintain a position suitable for writing / reading information to / from an information recording medium, and based on information detected by the head and indicating the distance between the information recording medium and the head. The second
Selectively driving the coarse movement mode drive circuit and the second fine movement mode drive circuit to drive the second actuator, and controlling the head to maintain a desired interval with respect to the information recording medium. A driving device using an electromechanical transducer element. 4. The information recording medium according to claim 1, wherein said information recording medium is a rotating disk.
A driving device using the electromechanical conversion element according to claim 3. 5. A driving direction of the head by the first actuator is a direction parallel to an information recording surface of a rotating disk constituting the information recording medium, and a driving direction of the head by the second actuator is the information recording medium. 5. The driving device using the electromechanical transducer according to claim 4, wherein the direction is perpendicular to the information recording surface of the rotating disk constituting the device.