JP2005312208A - Recoilless displacement enlarging/positioning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a recoilless displacement enlarging/positioning apparatus having a displacement mechanism with a symmetry property, improving a displacement enlargement ratio, hardly generating an unnecessary resonance, and enabling a fast and accurate displacement. <P>SOLUTION: First and second arms 21, 22 are coupled to a link 41 through hinges. Ends of third and fourth arms are coupled to a link 42 through hinges. The other ends of the first and third arms are coupled to a link 43 through hinges. The other ends of the second and fourth arms are coupled to a link 44 through hinges. A silhouette has a symmetric lozenge. A first PZT 56 is attached between an attaching section 55 and the link 41. A second PZT is attached between the attaching section 55 attached to a body and the link 42. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is effective when used, for example, in a magnetic recording evaluation apparatus that evaluates magnetic recording on a magnetic disk. In this case, the magnetic head is positioned at a predetermined track position on the magnetic disk with high speed and high accuracy. TECHNICAL FIELD The present invention relates to a reactionless displacement magnifying positioning device.

  Along with a marked increase in recording density and speed of a hard disk drive, a magnetic recording evaluation apparatus that performs recording / reproduction evaluation of magnetic recording on a magnetic disk is required to have a high-speed and high-precision positioning technology for the magnetic head. In addition, this magnetic recording evaluation apparatus requires an alignment mechanism for dealing with various head gimbal assemblies (HGA), but does not require a large seek operation.

  In response to these requirements, a PZT actuator composed of a PZT (piezoelectric element) with a small maximum displacement but high response and a mechanism for expanding the displacement of the PZT is mounted, and this actuator is driven in the vicinity of the HGA. Thus, a displacement magnifying mechanism that improves track followability by increasing the control band is employed.

  FIG. 1 shows a conventional displacement enlarging mechanism. 1 is a PZT, 2 is a mounting portion, 3 is an HGA support portion, 4 is a displacement enlargement portion, 5 and 6 are arms (links), 7 and 8 are PZT support portions, and 9 is a notch portion.

  This mechanism employs a parallel link mechanism. For attachment to the apparatus main body, bolts or the like are inserted into the two holes 2a, 2b of the attachment part 2 and attached to the attachment part to the apparatus main body. The HGA is fixed to the HGA support 3 using screws. This mechanism is a combination of a lever mechanism and a parallel link spring, and a hinge using elastic deformation is employed. The minute displacement of PZT1 appears to be magnified A / B times in the HGA support 3. However, this mechanism has the following four problems.

  (1) The expansion and contraction force of PZT 1 is concentrated on the position of the notch 9 of the arm 5. Since the rigidity of the arm 5 cannot be sufficiently high with respect to this force, the arm 5 is elastically deformed. Further, the rigidity of the PZT support portion 8 that directly receives the expansion / contraction force on the PZT 1 cannot be sufficiently high with respect to the generated force of the PZT 1 because the PZT support portion 8 has a cantilever shape. The support portion 8 is elastically deformed. As a result, the displacement magnification rate becomes smaller than the assumed value A / B, and the minute displacement of PZT1 cannot be efficiently expanded.

  (2) When the PZT 1 is operated at high speed, the PZT attachment portion 8 vibrates, and the reaction force vibrates the attachment portion 2 to the apparatus body, inducing vibration of the entire mechanism, and high-speed and high-precision positioning. It becomes a big obstacle.

  (3) The inertial force acting on the HGA support portion 3 that moves due to the expansion and contraction force of the PZT1 becomes extremely large by operating the PZT1 at high speed, and the attachment portion 2 to the linear motion stage of the apparatus main body that receives this inertial force When excited, it induces vibration of the entire mechanism and becomes a major obstacle to high-speed and high-precision positioning.

(4) The displacement expansion ratio of the mechanism and the resonance frequency are in a trade-off relationship, and a dramatic improvement in the resonance frequency for improving controllability cannot be expected.
JP 2003-157632 A

  As described above, with the conventional mechanism, the arm 5 and the PZT support portion 8 may be elastically deformed. In this case, the displacement magnification rate becomes smaller than the assumed value A / B, and the minute displacement of PZT1 cannot be efficiently expanded. The vibration of the PZT attachment portion 8 vibrates the attachment portion 2 at the high speed of the PZT 1 and induces vibration of the entire mechanism, which may be a major obstacle to high-speed and high-accuracy positioning. When the PZT 1 is operated at high speed, the inertial force acting on the HGA support part 3 becomes extremely large, and the attachment part 2 to the linear motion stage of the apparatus main body is vibrated, inducing vibration of the entire mechanism, and high speed and high accuracy. Can be a major obstacle to proper positioning. The displacement expansion ratio of the mechanism and the resonance frequency are in a trade-off relationship, and it is not possible to expect a dramatic improvement in the resonance frequency to improve controllability.

  Accordingly, the present invention has been made to solve the above-described problems. By providing symmetry to the displacement mechanism, the displacement magnification rate is improved and unnecessary resonance is less likely to occur. It is an object of the present invention to provide a reactionless displacement magnifying positioning device capable of accurate displacement.

  In order to solve the above-mentioned problem, the present invention has an arrangement relationship in which the first and second arms form an acute angle, and each of the one end portions is connected via a hinge portion, The third arm and the fourth arm form an acute angle, each of which has an end portion coupled via a hinge portion, and the first arm and the third arm have an obtuse angle. Each of the other end portions of the third connecting portions connected via hinges, and the second arm and the fourth arm are obtuse angles. A position including an intersection of a fourth connecting part, the other end part of which is connected via a hinge part, a line connecting the first and second connecting parts, and a line connecting the third and fourth connecting parts The attachment part to the device main body and the attachment to the device main body A first PZT attached between the attaching portion and the first connecting portion, and a second PZT attached between the attaching portion to the apparatus main body and the second connecting portion. ing.

  According to said means, the said 3rd and 4th connection part can carry out expansion displacement according to expansion-contraction of 1st and 2nd PZT.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 2A and 2B are one embodiment of the present invention. 2A is a plan view, and FIG. 2B is an external perspective view. As shown in the figure, the first to fourth arms 21, 22, 23, and 24 have a substantially rhombic arrangement relationship. The shape is symmetrical with respect to the X axis and the Y axis.

  Here, the first and second arms 21 and 22 are in an arrangement relationship that forms an acute angle (for example, 36.87 degrees), and one end portions of the first and second arms 21 and 22 are connected to the first connecting portion 41 via the hinge portions 31 and 32, respectively. Are connected. Further, the third arm 23 and the fourth arm 24 are in an arrangement relationship that forms an acute angle (for example, 36.87 degrees), and one end portion of each of the third arm 23 and the fourth arm 24 is connected to the second connection portion 42 via the hinge portions 33 and 34, respectively. Are connected.

  Further, the first arm 21 and the third arm 23 are arranged to form an obtuse angle, and the other ends of the first arm 21 and the third arm 23 are coupled to the third connecting portion 43 via hinges 31a and 33a, respectively. Then, the second arm 22 and the fourth arm 24 are arranged to form an obtuse angle, and one end portions of the second arm 22 and the fourth arm 24 are coupled to the fourth connecting portion 44 via hinge portions 32a and 34a, respectively.

  Mounting to the apparatus body so as to include the intersection of the line connecting the first and second connecting portions 41 and 42 (Y axis) and the line connecting the third and fourth connecting portions 43 and 44 (X axis) The part 55 is arranged. A first PZT 56 is attached between the attachment portion 55 to the apparatus main body and the first connection portion 41, and a first PZT 56 is provided between the attachment portion 55 to the apparatus main body and the second connection portion 42. Two PZTs 57 are attached. In the above apparatus, the maximum length in the longitudinal direction is, for example, 49.96 mm, and the maximum length in the short side direction is, for example, 26.0 mm. Moreover, the notch width provided in order to form a hinge part is about 1 mm. The lengths of the arms 21-24 are the same.

  As described above, this embodiment employs a hinge that applies elastic deformation, and adopts a shape (diamond) that is symmetrical with respect to the diagonal axes X and Y that are orthogonal to each other as the shape of the PZT fine actuator. There is a feature in the point. The center of the attachment portion 55 to the apparatus main body is the position of the intersection of the diagonal axes, and the shape of the attachment portion 55 to the apparatus main body is symmetric with respect to the orthogonal X and Y axes.

  Two PZTs 56 and 57 having the same characteristics are arranged so as to face each other with the Y axis as the center line and the attachment portion 55 to the apparatus main body sandwiched therebetween. The shape of the displacement enlarging part (area surrounded by the line connecting the first to fourth arms and the first to fourth connecting parts) for enlarging the minute displacement of the PZTs 56 and 57 is symmetrical with respect to the orthogonal X and Y axes. Mechanism.

  As a result, when an equal voltage is applied to two PTs 56 and 57 having the same characteristics, the displacement of each part of the mechanism due to the expansion and contraction of the PZTs 56 and 57 is symmetric with respect to the X axis and the Y axis. The directional displacement and the Y-axis direction displacement of each part of the mechanism on the X-axis become vibration nodes, which are uncontrollable points in modern control theory (not affected by control). Therefore, even if the PZTs 56 and 57 are operated at high speed, the (HGA support part (for example, the third connecting part 43) is displaced only in the X-axis direction, and the generated force of the PZTs 56 and 57 and the inertial force generated by each part of the mechanism are not It is a mechanism that is offset and hardly exerts an unnecessary force on the attachment portion 55 to the apparatus main body, and is a mechanism that avoids the problems (2) and (3) of the conventional displacement enlarging mechanism described above.

  In addition, by realizing the uncontrollable control established by the symmetry of the mechanism, the low-order vibration mode asymmetrical to the X and Y axes with the bending modes of the PZTs 56 and 57 is disabled from the generated force of the PZTs 56 and 57, It is a mechanism that dramatically improves the resonance frequency of the mechanism, and avoids the problem (4) of the conventional displacement enlargement mechanism described above. Furthermore, the mechanism of the present invention (axisymmetric (diamond) mechanism) can give the portions 55, 41, and 42 that directly receive the PZT 56, 57 generated force sufficient rigidity, thereby reducing the displacement magnification rate due to elastic deformation. This is a difficult mechanism, and is a mechanism that avoids the problem (1) of the conventional displacement enlarging mechanism.

  A more specific description of the configuration of the present invention will be given. The present invention has an attachment portion 55 for the apparatus main body, two PZTs 56 and 57 having the same characteristics, and a displacement enlargement portion. The attachment to the apparatus main body is performed using bolts or the like in the two circular holes of the attachment part 55 to the apparatus main body near the intersection of the X axis and the Y axis, and the HGA support part (third connection part 43) is connected to the HGA. Secure with screws.

  In this configuration, a lever mechanism is combined with an axisymmetric (rhombus) link-shaped spring, and a hinge using elastic deformation is employed. The PZTs 56 and 57 expand and contract in the Y-axis direction by applying a voltage to the electrodes via the lead wires. The displacement of the HGA with respect to the displacement of the PZTs 56 and 57 is enlarged A / B times by the displacement enlargement unit. In the present invention, two PZTs 56 and 57 having the same characteristics are arranged in series with an attachment portion 55 to the apparatus main body linear motion stage interposed therebetween, and the whole mechanism is a symmetric mechanism with respect to the Y and X axes. When attaching the HGA to the HGA support (third connecting portion 43), in order to maintain the symmetry of the mass with respect to the Y axis, the Counterweight (counterweight) of the same mass as the HGA is attached to the Counterweight attaching portion (the fourth weight). Fastened to the connecting part 44) with screws.

  More specific operation and specific action of the above apparatus will be described. As a result of measuring the static characteristics of this actuator manufactured with A / B = 3, the part directly receiving the generated force of PZT 56, 57 when a trapezoidal wave with an input voltage of 50 V is input to PZT 56, 57 at a frequency of 100 Hz (first) FIG. 3A shows the displacement in the Y direction of the first connecting portion 41 or the second connecting portion 42), and FIG. 3B shows the displacement in the X direction of the HGA support portion (third connecting portion 43).

  The displacement in the Y direction of the portion (the first coupling portion 41 or the second coupling portion 42) that directly receives the generated force of the PZTs 56 and 57 is 2 μm, and the displacement in the X direction of the HGA support portion (the third coupling portion 43) is It was 5.8 μm. As a result, the displacement enlargement ratio was 2.9, which was substantially equal to the assumed value A / B.

  FIG. 4 also shows the frequency characteristics of the transfer function from the input voltage to the PZTs 56 and 57 in FIG. 2 to the X-direction displacement of the HGA support part (third connection part 43) as a measurement result of the dynamic characteristics of this actuator. Is shown. It can be seen that it has the characteristics of a typical one-degree-of-freedom second-order lag element having a resonance frequency of 9.9 kHz. The upper stage of FIG. 4 shows frequency vs. phase characteristics, and the lower stage shows frequency vs. amplitude characteristics.

  The PZTs 56 and 57 have an HGA support with an input signal that is 1/100 of the amplitude ± 5V when a sine wave with an amplitude of ± 5V sweeping at a frequency of 100Hz-50kHz is applied with an offset voltage of 50V. This is a frequency response between input and output when a value of 1 / 17.5 of the X-axis direction displacement (μm) of the part is used as an output signal.

  FIG. 5 shows an example of use of the apparatus of the present invention. As the PZTs 56 and 57, stacked types are used. An input signal is given through the lead wires 61, 62, 63, 64, and an X-direction displacement of the HGA support portion (third connecting portion 43) is obtained. An HGA 71 is attached to the HGA support 43, and a magnetic head 72 is attached to the tip. The magnetic head 72 faces the recording track 75 of the magnetic disk 74. The attachment portion 55 is attached to the fixing portion of the apparatus main body by screws 81 and 82.

  As described above, in this embodiment, the resonance frequency of the conventional parallel link mechanism is 3.3 kHz, whereas the resonance frequency of the axially symmetric (diamond) mechanism of this embodiment is three times that of the conventional structure. did. According to the present embodiment, as described above, when the head is driven at a high speed, all the inertial force generated by the moving part is canceled inside the mechanism due to the complete symmetry of the mechanism (the resultant force is zero). Thus, a reactionless drive in which no driving force is applied to the attachment portion to the apparatus main body is realized.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. The scope of this modification is also within the scope of the present invention. For example, it is not always necessary to take a perfect Y-axis symmetrical shape. The symmetry may not be perfect due to factors such as magnification, counterweight, and usage conditions.

The figure which shows the conventional displacement expansion mechanism. FIGS. 2A and 2B are diagrams illustrating an embodiment of the present invention, in which FIG. 2A is a plan view and FIG. 2B is a perspective view. The figure which measures and shows the displacement of the connection part 41 and the connection part 43 in order to demonstrate the function of the apparatus of this invention. The figure which shows the measurement result of the dynamic characteristic of the apparatus of this invention. Explanatory drawing which shows an example of 1 use for the apparatus of this invention.

Explanation of symbols

  21-24 ... 1st to 4th arm, 31, 31, 33, 34, 31a, 32a, 33a, 34a ... Hinge part, 41-44 ... 1st to 4th connecting part, 55 ... to the apparatus main body Attachment part, 56, 57 ... PZT (piezoelectric element).

Claims (5)

First to fourth arms;
A first connecting portion in which the first and second arms are in an arrangement relationship that forms an acute angle, and each one end portion is coupled via a hinge portion;
The third arm and the fourth arm are in an arrangement relationship that forms an acute angle, and each of the one end portions is coupled via a hinge portion;
The first arm and the third arm are in an arrangement relationship that makes an obtuse angle, and each of the other end portions is coupled via a hinge portion, a third connecting portion,
The second arm and the fourth arm are in an arrangement relationship that makes an obtuse angle, and each of the other end portions is coupled via a hinge portion, a fourth connecting portion;
An attachment portion to the apparatus main body disposed at a position including an intersection of a line connecting the first and second connecting portions and a line connecting the third and fourth connecting portions;
A first piezoelectric element attached between the attachment portion to the apparatus main body and the first connection portion, and a second piezoelectric element attached between the attachment portion to the apparatus main body and the second connection portion. A non-reaction type displacement enlarging positioning apparatus comprising: a piezoelectric element. 2. The reactionless displacement expansion positioning according to claim 1, wherein a head gimbal assembly is attached to the third connecting portion, and a counterweight is attached to the fourth connecting portion. apparatus. The reactionless displacement magnifying positioning device according to claim 1, wherein the first to fourth arms have the same length. 2. The reactionless displacement magnifying positioning device according to claim 1, wherein the first and second piezoelectric elements have the same characteristics. 2. The reactionless displacement magnifying positioning device according to claim 1, wherein the first to fourth arms and the hinge portions have elasticity.

Images