JP2004199731A - Composite type linear actuator and spring member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite type linear actuator which is provided with an electromagnetic type linear actuator to stabilize vibration characteristics. <P>SOLUTION: In the composite type linear actuator, a sub-movable section which constitutes the electromagnetic type linear actuator is fixed to a sub-fixed section in a linearly movable manner through an upper side leaf spring (322U) and a lower side leaf spring (322L). By making the shapes of the leaf springs (322U) and (322L) identical, the resonance frequencies of the leaf springs are made identical and the vibration characteristics of the electromagnetic type linear actuator are stabilized. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a linear tape storage system typified by DLT (Digital Linear Tape) and LTO (Linear Tape Open), and in particular, to an electromagnetic type that can be used as a head feed mechanism of a magnetic tape head actuator assembly used therein. Composite) linear actuator.
[0002]
[Prior art]
This type of linear tape storage system has been developed as a backup for computer systems, and various types have been conventionally proposed. For example, a digital linear tape drive as a DLT is disclosed in, for example, Patent Document 1 or the like.
[0003]
A digital linear tape drive (hereinafter, also simply referred to as “drive device”, “tape drive”, or “drive”) is a tape cartridge having a single reel (supply reel) (hereinafter, also simply referred to as “cartridge”). And a take-up reel is built therein. When the tape cartridge is mounted on the tape drive, the magnetic tape is pulled out of the tape cartridge and is taken up by a take-up reel via a head guide assembly (HGA). The head guide assembly is for guiding the magnetic tape (hereinafter, also simply referred to as “tape”) drawn from the tape cartridge to the magnetic head. The magnetic head exchanges information with the tape. The head guide assembly generally consists of a boomerang-shaped aluminum plate and six large guide rollers using bearings.
[0004]
In addition, the head guide assembly is also called a tape guide assembly, which is disclosed in, for example, Patent Document 2. An example of the guide roller is disclosed in Patent Document 3.
[0005]
Generally, a tape drive includes a substantially rectangular parallelepiped housing having a common base, as described in Patent Document 4, for example. The base has two spindle motors (reel motors). The first spindle motor has a spool (take-up reel) permanently attached to the base, the spool being sized to receive the magnetic tape flowing at a relatively high speed. A second spindle motor (reel motor) is adapted to receive a removable tape cartridge. The removable tape cartridge is manually or automatically inserted into the drive through a slot formed in the drive housing. When the tape cartridge is inserted into the slot, the cartridge engages with a second spindle motor (reel motor). Before rotating the first and second spindle motors (reel motors), the tape cartridge is connected to a permanently mounted spool (take-up reel) by a mechanical buckling mechanism.
Many rollers (guide rollers) located between the tape cartridge and the permanent spool guide the magnetic tape as it moves back and forth between the tape cartridge and the permanently mounted spool at relatively high speeds. I do.
[0006]
Such a digital linear tape drive requires a device for the take-up reel to pull the tape from the supply reel. Such a pulling device is disclosed, for example, in US Pat. According to this publication, take-up leader means (first tape leader) is connected to the take-up reel, and supply tape leader means (second tape leader) is fixed to the tape on the supply reel. The first tape leader has a tab at one end, the second tape leader has a locking hole, and the tab is engaged with the locking hole.
[0007]
Further, a mechanism for joining the first tape reader to the second tape reader is required. Such a joining mechanism is disclosed, for example, in Patent Document 6.
[0008]
Further, in Patent Literature 7, the end of the leader tape is locked to the tape end hooking portion of the tape cartridge without the need for an ear piece protruding to the side of the leader tape (second tape leader). The disclosed "leader tape engaging portion structure" is disclosed.
[0009]
Patent Document 8 discloses a lock system for preventing a take-up reel of a tape drive from rotating when a tape cartridge is not inserted into the drive.
[0010]
On the other hand, an example of a tape cartridge to be mounted on a digital linear tape drive is disclosed in Patent Document 9.
[0011]
Patent Document 10 discloses a "tape drive" in which a tape reader can be pushed from a tape cartridge to a take-up reel without using a buckling mechanism or a take-up leader.
[0012]
Note that the tape drive further includes a magnetic tape head actuator assembly, which is positioned between the take-up spool and the tape cartridge on a tape path defined by a plurality of rollers. In operation, the magnetic tape flows back and forth between the take-up spool and the tape cartridge and comes into close proximity to the magnetic head actuator assembly while flowing over a defined tape path. An example of such a magnetic head actuator assembly is disclosed in Patent Document 4 mentioned above.
[0013]
The actuator assembly includes a tape head assembly (hereinafter, also simply referred to as “head assembly”) and a head feed mechanism. The head assembly includes a magnetic head (head) extending in a vertical direction, a head holder for holding the magnetic head, and a pair of flexible printed circuits (C) for electrically connecting the magnetic head to an external circuit. FPC).
[0014]
On the other hand, the head feed mechanism is for moving the head assembly up and down while holding the head assembly. The conventional head feed mechanism is provided with a threaded lead screw (threaded shaft) as disclosed in Patent Document 4, and the head assembly is moved up and down mechanically by rotating the lead screw. (Linear motion). In other words, a “mechanical linear actuator” is employed as a conventional head feed mechanism.
[0015]
In such a mechanical linear actuator, the position control of the head assembly is performed by open loop control. In the DLT, the storage capacity has been increased. In the first generation DLT “DLT1”, the normal storage capacity is 40 Gbytes, and the storage capacity when compressed is 80 Gbytes. In the second generation DLT “DLT2”, the normal storage capacity is 80 Gbytes, and the storage capacity when compressed is 160 Gbytes. In a DLT having such a storage capacity, a mechanical linear actuator can sufficiently cope with it.
[0016]
However, the “DLT3”, which is the next generation (third generation) DLT, has a large storage capacity (high recording density) with a normal storage capacity of 160 Gbytes and a compressed storage capacity of 320 Gbytes. Therefore, when the mechanical linear actuator described above is used as the linear actuator for DLT having this large storage capacity, it is difficult to control the head assembly to a desired position with high accuracy.
[0017]
On the other hand, in order to solve the problem in such a mechanical linear actuator, an “electromagnetic linear actuator” that moves the head assembly up and down (linear motion) using electromagnetic force is adopted as a head feed mechanism. Has been proposed in which the position control is performed by closed loop (feedback) control (for example, see Patent Document 11). Since the electromagnetic linear actuator employs feedback control as a control method, it is possible to always control the head assembly to a desired position accurately even if the magnetic tape fluctuates up and down during traveling.
[0018]
Such an electromagnetic linear actuator generally includes a fixed portion, a movable portion that holds the head assembly (elevated object) so as to be able to move up and down in the vertical direction with respect to the fixed portion, and a movable portion of the movable portion. It has a guide that restrains (restricts) movement in directions other than the (elevation) direction, and a base for attaching the guide.
[0019]
Here, the electromagnetic linear actuator can be divided into two types. The first type is a “movable magnet type” electromagnetic linear actuator, which has a magnet in a movable part and a coil in a fixed part. The second type is a “moving coil type” electromagnetic linear actuator, which has a magnet and a yoke in a fixed portion and a coil in a movable portion.
[0020]
As described above, the electromagnetic linear actuator is suitable as a DLT actuator having a large storage capacity. However, as described above, the control method (control system) is completely different between the mechanical linear actuator and the electromagnetic linear actuator. Therefore, when this electromagnetic linear actuator is used as a DLT linear actuator of a lower model (that is, a first generation or a second generation), the control system for the mechanical linear actuator that has been incorporated so far is used at all. Therefore, it is necessary to newly install a control system suitable for the electromagnetic linear actuator. That is, it is necessary to make a design change to the DLT of the lower model.
[0021]
In order to solve such a problem, not only mechanical linear actuators but also electromagnetic linear actuators as third-generation (higher-order) DLT linear actuators compatible with lower-order DLTs are used. A "composite linear actuator" that can operate is being considered. That is, the composite linear actuator is a combination of a mechanical linear actuator and an electromagnetic linear actuator. In such a composite linear actuator, coarse position control (open loop control) of the head assembly is performed using a mechanical linear actuator, and precise position control (closed loop control) of the head assembly is performed using an electromagnetic linear actuator. It can be carried out.
[0022]
More specifically, a composite linear actuator is a mechanical linear actuator including a lead screw having a rotation center axis extending in the axial direction, and a main movable portion that linearly moves in the axial direction by rotation of the lead screw. Including. The main movable portion operates as an electromagnetic linear actuator including a sub-fixed portion and a sub-movable portion that linearly moves in the axial direction by electromagnetic force with respect to the sub-fixed portion. Note that the sub-fixed portion is called a VCM (voice coil motor) fixed portion, and the sub-movable portion is called a VCM movable portion. The sub-fixing portion has a yoke and a magnet, and the sub-movable portion includes an air core coil. This air-core coil is fixed to a head holder (attachment) that holds the magnetic head.
[0023]
The sub movable portion must be supported so as to be movable in the axial direction with respect to the sub fixed portion. As such a supporting means, a method is conceivable in which the auxiliary movable portion is supported so as to be linearly movable with respect to the auxiliary fixed portion via an upper leaf spring and a lower leaf spring. The present applicant (the present inventors) has already proposed (filed) an integrally formed sub movable portion and an upper leaf spring and a lower leaf spring, as described later with reference to the drawings. (See Japanese Patent Application No. 245226, 2002) (hereinafter, this application will be referred to as "prior application").
In this prior application, as will be described later in detail with reference to the drawings, due to the arrangement of the projections inserted into the annular grooves formed in the lead screw gear, the shapes of the upper leaf spring and the lower leaf spring are different. I have.
[0024]
[Patent Document 1]
JP-A-9-198639
[0025]
[Patent Document 2]
Japanese Unexamined Patent Publication No. Hei 9-500753
[0026]
[Patent Document 3]
JP 2000-100025 A
[0027]
[Patent Document 4]
JP 2000-501547 A
[0028]
[Patent Document 5]
Japanese Patent Publication No. 3-7595
[0029]
[Patent Document 6]
Japanese Patent Publication No. 6-39027
[0030]
[Patent Document 7]
JP 2000-100116 A
[0031]
[Patent Document 8]
JP-A-11-86381
[0032]
[Patent Document 9]
JP 2000-149491 A
[0033]
[Patent Document 10]
JP-A-11-316991
[0034]
[Patent Document 11]
JP 2002-198219 A
[0035]
[Problems to be solved by the invention]
As described above, in the composite linear actuator of the prior application, since the shapes of the upper leaf spring and the lower leaf spring constituting the electromagnetic linear actuator are different, different resonance frequencies are respectively applied to the upper leaf spring and the lower leaf spring. Will exist. As a result, when the electromagnetic linear actuator is assembled, the number of resonance modes increases. Here, the resonance frequency is referred to as a primary resonance frequency, a secondary resonance frequency, or the like from a lower frequency.
[0036]
When performing servo control on the above-mentioned electromagnetic linear actuator, a frequency range between the primary resonance frequency and the secondary resonance frequency is generally used. Therefore, it is desirable that the primary resonance frequency is low and the secondary resonance frequency is high.
[0037]
However, when the shapes of the upper leaf spring and the lower leaf spring are different, for example, the primary resonance frequency and the secondary resonance frequency of the upper leaf spring are respectively equal to the primary resonance frequency and the secondary resonance vibration of the lower leaf spring. Higher than the number. In this case, in the servo control of the electromagnetic linear actuator, the primary resonance frequency is the primary resonance frequency of the upper leaf spring, and the secondary resonance frequency is the secondary resonance frequency of the lower leaf spring. Will be used. As a result, in the servo control of the electromagnetic linear actuator, the range of usable frequencies is narrowed, which is disadvantageous and may cause unstable vibration characteristics.
[0038]
Accordingly, an object of the present invention is to provide a composite linear actuator including an electromagnetic linear actuator whose vibration characteristics are stabilized.
[0039]
Another object of the present invention is to provide a composite linear actuator including an electromagnetic linear actuator that stabilizes vibration characteristics by equalizing the resonance frequency of the upper leaf spring and the lower leaf spring. is there.
[0040]
[Means for Solving the Problems]
According to the present invention, the lead screw (41) having the rotation center axis extending in the axial direction, and the main movable parts (42, 43, 48A, 49A, 60A) linearly moving in the axial direction by the rotation of the lead screw. , 30), the main movable part is linearly moved in the axial direction by the electromagnetic force with respect to the sub-fixed part (42, 43, 48A, 49A, 60). A composite linear actuator that operates as an electromagnetic linear actuator including a movable sub-portion (32), wherein the sub-fixed portion has yokes (62, 63) and a magnet (61), and the sub-movable portion is an air core. A composite linear actuator including a coil (35), and the sub-movable portion supported linearly movable with respect to the sub-fixed portion via an upper leaf spring (322U) and a lower leaf spring (322L). In the composite linear actuator, characterized in that the upper leaf spring (322U) the shape of the lower leaf spring (322L) are identical is obtained.
[0041]
Further, according to the present invention, the sub-movable portion of the electromagnetic linear actuator which constitutes the composite linear actuator and has the sub-fixed portions (42, 43, 48A, 49A, 60) and the sub-movable portion (32) is provided. A spring member for supporting the sub-fixed portion so as to be able to move linearly and having an upper leaf spring (322U) and a lower leaf spring (322L) of the same shape is selected.
[0042]
It is to be noted that the reference numerals in the parentheses are provided for facilitating the understanding of the present invention, are merely examples, and are not limited thereto.
[0043]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0044]
To facilitate understanding of the present invention, a composite linear actuator disclosed in the prior application will be described first.
[0045]
Referring to FIG. 1, a tape drive including the magnetic tape head actuator assembly of the prior application will be described. FIG. 1 is a perspective view showing the tape drive with the upper lid removed.
[0046]
The tape drive 10 is for receiving a tape cartridge (not shown), and has a take-up reel 11 built therein. The take-up reel 11 is also called a spool. The tape drive 10 has a substantially rectangular parallelepiped housing (chassis) 12 having a common base. The base has two spindle motors (reel motors) 13 and 14. The first spindle motor 13 has a spool (take-up reel) 11 permanently attached to the base of the housing 12, which spool 11 receives a magnetic tape (not shown) flowing at a relatively high speed. The size is determined. A second spindle motor (reel motor) 14 is adapted to receive a removable tape cartridge. The removable tape cartridge is manually or automatically inserted into the drive 10 through a slot 16 formed in the housing 12 of the drive 10 along the insertion direction indicated by arrow A.
[0047]
When the tape cartridge is inserted into the slot 16, the cartridge engages with the second spindle motor (reel motor) 14. Before rotating the first and second spindle motors (reel motors) 13 and 14, the tape cartridge is transferred to a permanently mounted spool (take-up reel) 11 by a mechanical buckling mechanism (not shown). Connected. Many rollers (guide rollers) 15 positioned between the tape cartridge and the permanent spool 11 are used when the magnetic tape moves back and forth between the tape cartridge and the permanently mounted spool 11 at a relatively high speed. Guide it.
[0048]
The housing 12 is formed of a sheet metal press chassis made of an iron-based magnetic material.
[0049]
The tape drive 10 further includes a magnetic tape head actuator assembly (hereinafter, also simply referred to as “actuator assembly”) 20, which is arranged on a tape path (not shown) defined by the plurality of rollers 15. It is located between the take-up spool 11 and the tape cartridge. In operation, the magnetic tape flows back and forth between the take-up spool 11 and the tape cartridge and is in close proximity to the magnetic tape head actuator assembly 20 while flowing on a defined tape path.
[0050]
Hereinafter, a conventional actuator assembly 20 will be described with reference to FIGS. FIG. 2 is a perspective view showing the appearance of the actuator assembly 20 viewed from the front side, and FIG. 3 is a perspective view showing the appearance of the actuator assembly 20 shown in FIG. 2 viewed from the back side. 4 is a perspective view showing the appearance of the actuator assembly 20 shown in FIG. 2 as viewed from the back side, and FIG. 5 is an exploded perspective view of the actuator assembly 20 shown in FIG.
[0051]
As shown in FIG. 5, the actuator assembly 20 is a composite linear actuator, and includes a tape head assembly (hereinafter, also simply referred to as “head assembly”) 30 and a head feed mechanism 40.
[0052]
The head assembly 30 includes a magnetic head (head) 31 extending in the vertical direction, a head holder 32 for holding the magnetic head 31 movably in the vertical direction as described later, and a magnetic head 31 and an external circuit (FIG. (Not shown) and a pair of flexible printed circuits (FPCs) 33 for electrically connecting between them. The head holder 32 is also called a carriage.
[0053]
As shown in FIGS. 6 and 7, the head holder 32 is opposed to the head mounting portion 321 on which the magnetic head 31 is mounted, and from both upper and lower ends of the head mounting portion 321 in the vertical direction with respect to the head mounting portion 321. And a single upper leaf spring 322U and a lower leaf spring 322L. Each of the upper leaf spring 322U and the lower leaf spring 322L has a hole 322a for receiving the screw 34 (FIG. 5), and the head assembly 30 is connected to a bracket described later by screwing the screw 34 through the hole 322a. A head feed mechanism 40 to be described later is assembled.
[0054]
The head holder 32 further includes a pair of coil holding portions 323 extending in parallel with the directions in which the leaf springs 322U and 322L extend from both ends of the head mounting portion 321. The pair of coil holding portions 323 includes an electromagnetic type. A pair of air-core coils 35 constituting a sub movable portion of the linear actuator is held. Here, the head mounting part 321 and the coil holding part 323 are made of resin. The head mounting portion 321, the coil holding portion 323, the pair of upper leaf springs 322U, the pair of lower leaf springs 322L, and the pair of air core coils 35 are integrally formed by outsert molding.
[0055]
As shown in FIGS. 8 and 9, the pair of upper leaf springs 322U and the pair of lower leaf springs 322L are configured as a spring member integrated with the spring support 322S, and are opposed to each other from the spring support 322S. It is bent into a U-shape.
[0056]
A large number of holes 322b, 322c, 322d are formed in the spring support 322S. Of these holes, a pair of left and right holes 322b and 322c at the center support the spring support 322S with a single rod (not shown) when the spring support 322S is outsert molded with the head mounting portion 321. The other holes 322d are for allowing the molten resin to flow evenly to the front side and the back side of the spring support 322S during outsert molding. One of the holes 322c of the support hole is a long hole. This is to allow an error when the spring member is made by press working. Anyway, at least three holes are formed in the spring support 322S. The holes 322a, 322b, 322c, and 322d may be formed by pressing or may be formed by etching.
[0057]
As described above, the head mounting portion 321, the pair of upper leaf springs 322 </ b> U, and the pair of lower leaf springs 322 </ b> L are formed as molded products by outsert molding. Further, the pair of upper leaf springs 322U and the pair of lower leaf springs 322L are formed as one piece.
[0058]
2 to 5, the head feed mechanism 40 includes a threaded lead screw (threaded shaft) 41 having a rotation center axis extending in a vertical direction as a rotating part, and a lead screw as a linear moving part. The head actuator 42 includes a head lift 42 that moves up and down along the rotation center axis according to the rotation of the head 41, and a preload bush 43 that prevents backlash of the head actuator assembly 20.
[0059]
The lead screw 41 is provided at its lower end with a lead screw gear 44 for rotating the lead screw 41 around a rotation center axis by another driving means (for example, a stepping motor). The lead screw gear 44 has an annular groove 44a. A locking piece 44b is provided in the annular groove 44a.
[0060]
The head lift 42 has a bottom part 421, a ceiling part 422, and a semi-cylindrical part 423 that supports the bottom part 421 and the ceiling part 422. Each of the bottom portion 421 and the ceiling portion 422 has an arm extending in both outer directions of the semi-cylindrical portion 423. The semi-cylindrical portion 423 has a gutter shape with a hollow central portion and an opening corresponding to the semi-cylindrical portion. Therefore, the outer shape of the head lift 42 has a substantially I-shape when viewed from the side, and moves the tape head assembly 30 up and down while holding the tape head assembly 30 up and down. In this head lift 42, a preload bush 43 is disposed inside the hollow opening of the semi-cylindrical portion 423. A preload spring (not shown) is placed between the preload bush 43 and the ceiling 422 in a compressed state. The preload spring is a compression coil spring. The combination of the preload bush 43 and the preload spring functions as a backlash prevention mechanism for preventing the actuator assembly 20 from backlash.
[0061]
The bottom surface portion 421 has a bearing 45 having a claw-like projection engaged with the lead screw 41 on the inner surface fixed to the hollow opening position of the semi-cylindrical portion 423 on the upper surface of the circular opening position through which the lead screw 41 penetrates. The slide bearing 46 having a circular opening for allowing the lead screw 41 to pass therethrough is formed in the ceiling portion 422 at the hollow opening position of the semi-cylindrical portion 423.
[0062]
One arm of the bottom portion 421 extends laterally longer than the other arm, and a substantially U-shaped guide portion 47 is provided at the tip thereof. The guide portion 47 is fitted into the guide bar 17 shown in FIG. 1 and attached so as to be slidable in the vertical direction, thereby preventing the head lift 42 from rotating.
[0063]
As shown in FIG. 4, the bottom surface portion 421 has a columnar projection 421a projecting downward. The protrusion 421a is inserted into the annular groove 44a of the lead screw gear 44 as shown in FIG.
[0064]
The ceiling 422 has a screw hole 422a in each of the pair of arms. The upper bracket 48 for attaching the pair of upper leaf springs 322U of the head holder 32 to the ceiling 422 has a hole 48a for receiving the screw 34. As a result, the pair of upper leaf springs 322U of the head holder 32 is screwed into the screw holes 422a of the ceiling portion 422 through the holes 48a of the upper bracket 48 and the holes 322a of the leaf spring 322, thereby forming a ceiling. It is attached to the part 422.
[0065]
The bottom portion 421 also has a screw hole 421a in each of the pair of arms. The lower bracket 49 for attaching the pair of lower leaf springs 322L of the head holder 32 to the bottom surface portion 421 has a hole 49a for receiving the screw 34. As a result, the pair of lower leaf springs 322L of the head holder 32 are screwed into the screw holes 421a of the bottom surface portion 421 via the holes 49a of the lower bracket 49 and the holes 322a of the leaf spring 322. It is attached to the bottom part 421.
[0066]
The lower end of the lead screw 41 is rotatably attached to a housing (chassis) 12 (FIG. 1) via a bearing 51. The upper end of the lead screw 41 is rotatably mounted on the bearing holder 18 (FIG. 1) via a bearing 52, and the bearing holder 18 is fixedly installed on the housing (chassis) 12 (FIG. 1). .
[0067]
The lead screw gear 44 rotates the lead screw 41 directly connected with the coaxial rotation center axis as described above, for example, by driving a stepping motor. The rotation of the lead screw 41 about the rotation center axis cooperates with the backlash prevention mechanism to linearly move the head lift 42 in the direction in which the rotation center axis extends.
[0068]
A magnetic circuit (magnet or yoke) 60 constituting a sub-fixed portion of the electromagnetic linear actuator is attached to the head lift 42.
[0069]
More specifically, the magnetic circuit 60 has a pair of magnets 61 magnetized in the plate thickness direction and yoke portions provided on both side walls of the semi-cylindrical portion 423 of the head lift 42. The yoke portions extend in the up-down direction, a pair of center yokes 62 penetrating through the pair of air core coils 35 (FIGS. 5 and 6), a pair of back yokes 63, and the pair of back yokes. And a bridge portion 64 bridging between 63.
[0070]
Each of the back yokes 63 has a main surface 63a opposed to and spaced apart from the corresponding center yoke 62, and both ends 621 of the main yoke 63 are bent at substantially right angles by press working. Both ends 621 are in contact with both ends of the center yoke 62. The magnet 61 is in contact with the main surface 63a of the back yoke 63.
[0071]
The center yoke 62 has cutouts 62a at both ends. The both ends 631 of the back yoke 63 have protrusions 631a that fit into the cutouts 62a. The bridge 64 has a pair of holes 64a through which the screws 65 pass. The magnetic circuit 60 is fixedly attached to the head lift 42 by screwing a screw 65 to the back surface of the semi-cylindrical portion 423 of the head lift 42 through the hole 64a. The pair of back yokes 63 and the bridge portion 64 are integrally formed by pressing (bending).
[0072]
Anyway, the combination of the head lift 42, the preload bush 43, the magnetic circuit 60, the upper bracket 48, the lower bracket 49, the head assembly 30, and the screw 34 moves in the axial direction by the rotation of the lead screw 41. Acts as the main movable part of a mechanical linear actuator that moves linearly. The main movable portion is a sub-fixed portion having a head lift 42, a preload bush 43, a magnetic circuit 60, an upper bracket 48, and a lower bracket 49, and is linearly moved axially with respect to the sub-fixed portion by electromagnetic force. It operates as an electromagnetic linear actuator including a moving sub-movable section including the head assembly 30. The sub-fixing portion has yokes 62 and 63 and a magnet 61. The sub movable unit includes the air core coil 35.
[0073]
As is clear from FIGS. 7 to 9, in the composite linear actuator of the prior application, since the shapes of the upper leaf spring 322U and the lower leaf spring 322L constituting the electromagnetic linear actuator are different, the upper leaf spring 322U and the lower The side plate springs 322L have different resonance frequencies. As a result, when the electromagnetic linear actuator is assembled, the number of resonance modes increases. Here, as described above, the resonance frequencies are referred to as the primary resonance frequency fr1, the secondary resonance frequency fr2, and the like from the lower frequency.
[0074]
When performing servo control on the above-described electromagnetic linear actuator, a frequency range between the primary resonance frequency fr1 and the secondary resonance frequency fr2 is generally used.
Therefore, it is desirable that the primary resonance frequency fr1 is low and the secondary resonance frequency fr2 is high.
[0075]
However, in the composite linear actuator of the prior application, the width of the upper leaf spring 322U is smaller than the width of the lower leaf spring 322L due to the arrangement of the projection 421a inserted into the annular groove 44a formed in the lead screw gear 44. The upper leaf spring 322U and the lower leaf spring 322L have different shapes.
[0076]
In the case of having such a shape, as shown in FIG. 10, the primary resonance frequency fr1 (U) and the secondary resonance frequency fr2 (U) of the upper leaf spring 322U are each equal to 1 of the lower leaf spring 322L. It becomes higher than the secondary resonance frequency fr1 (L) and the secondary resonance frequency fr2 (L). In this case, when the electromagnetic linear actuator is servo-controlled, the primary resonance frequency fr1 is higher than the primary resonance frequency fr1 (U) of the upper leaf spring 322U, and the secondary resonance frequency fr2 is lower. The secondary resonance frequency fr2 (L) of the side leaf spring 322L will be used. As a result, in the servo control of the electromagnetic linear actuator, the usable frequency range (Rf in FIG. 10) becomes narrow, disadvantageous, and the vibration characteristics of the electromagnetic linear actuator may become unstable.
[0077]
Therefore, in the present invention, as described later, the shape of the upper leaf spring and the lower leaf spring are made the same by changing the arrangement of the protrusion 421a inserted into the annular groove 44a formed in the lead screw gear 44. By doing so, the resonance frequencies of the upper leaf spring and the lower leaf spring are made the same, thereby stabilizing the vibration characteristics of the electromagnetic linear actuator.
[0078]
11 and 12 show a configuration of a composite linear actuator 20A according to one embodiment of the present invention. FIG. 11 is a perspective view showing the appearance of the composite linear actuator 20A as viewed from the rear side, and FIG. 12 is a perspective view showing the appearance of the composite linear actuator 20A as viewed from the rear side. In the following, components (components) having the same functions as those of the composite linear actuator 20 of the prior application are denoted by the same reference numerals, and description thereof will be omitted. Only the differences will be described.
[0079]
First, the bottom portion 421A has a portion in front of the bottom portion 421 removed, and has a protruding portion 421A-1 protruding rearward, and a protrusion 421a is formed on the protruding portion 421A-1. Further, the shapes of the upper bracket 48A and the lower bracket 49A are more compact than those of the upper bracket 48 and the lower bracket 49 shown in FIGS.
[0080]
As shown in FIGS. 13 and 14, the pair of upper leaf springs 322U and the pair of lower leaf springs 322L have the same shape.
[0081]
In the case of having such a shape, as shown in FIG. 15, the primary resonance frequency fr1 (U) and the secondary resonance frequency fr2 (U) of the upper leaf spring 322U are each equal to 1 of the lower leaf spring 322L. It becomes equal to the secondary resonance frequency fr1 (L) and the secondary resonance frequency fr2 (L). In this case, when the electromagnetic linear actuator is servo-controlled, the primary resonance frequency fr1 (U) of the upper leaf spring 322U or the primary resonance frequency fr1 (L) of the lower leaf spring 322L is used as the primary resonance frequency fr1. As the secondary resonance frequency fr2, the secondary resonance frequency fr2 (U) of the upper leaf spring 322U or the secondary resonance frequency fr2 (L) of the lower leaf spring 322L is used. As a result, in the servo control of the electromagnetic linear actuator, the usable frequency range (Rf in FIG. 15) is widened, and the vibration characteristics of the electromagnetic linear actuator are stabilized.
[0082]
As described above, the present invention has been described with reference to the preferred embodiments, but the present invention is not limited to the above-described embodiments.
[0083]
【The invention's effect】
As is apparent from the above description, in the present invention, the resonance frequency of the upper leaf spring and that of the lower leaf spring are made the same by making the shape of the upper leaf spring and the lower leaf spring the same. The vibration characteristics of the actuator can be stabilized.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a tape drive including a magnetic tape head actuator assembly of the prior application with an upper lid removed.
FIG. 2 is a perspective view showing the appearance of the composite linear actuator of the prior application as viewed from the front side.
FIG. 3 is a perspective view showing the appearance of the composite linear actuator shown in FIG. 2 when viewed from the rear side.
FIG. 4 is a perspective view showing the appearance of the composite linear actuator shown in FIG. 2 when viewed from the back side.
FIG. 5 is an exploded perspective view of the composite linear actuator shown in FIG.
FIG. 6 is a perspective view showing a head holder used in the composite linear actuator shown in FIGS. 2 to 5 when viewed from the front side.
FIG. 7 is a perspective view showing the head holder shown in FIG. 6 as viewed from the back side.
8 is a perspective view showing the head holder shown in FIG. 6 and a spring member formed by outsert molding as viewed from the front side.
FIG. 9 is a perspective view showing the spring member shown in FIG. 8 as viewed from the back side.
FIG. 10 is a diagram showing vibration characteristics of an upper leaf spring and a lower leaf spring used for the spring members shown in FIGS. 8 and 9;
FIG. 11 is a perspective view showing the appearance of the composite linear actuator according to one embodiment of the present invention as viewed from the rear side.
FIG. 12 is a perspective view showing the appearance of the composite linear actuator according to one embodiment of the present invention as viewed from the back side.
FIG. 13 is a perspective view showing a spring member used in the composite linear actuator shown in FIGS. 11 and 12, as viewed from the front side.
FIG. 14 is a perspective view showing the spring member shown in FIG. 13 when viewed from the back side.
FIG. 15 is a diagram showing vibration characteristics of an upper leaf spring and a lower leaf spring used for the spring members shown in FIGS. 13 and 14;
[Explanation of symbols]
10 Tape drive
20A Composite linear actuator
30 Head assembly
31 magnetic head
32 head holder
321 Head mounting part
322U Upper leaf spring
322L Lower leaf spring
322S spring support
322b, 322c, 322d holes
323 coil holder
33 Flexible Printed Circuit (FPC)
34 screws
35 air core coil
40 Head feed mechanism
41 Lead screw
42 Head Lift
43 Preload bush
44 Lead screw gear
45 bearing
46 sliding bearing
47 Guide part
48A Upper bracket
49A Lower bracket

Claims (2)

A mechanical linear actuator including a lead screw having a rotation center axis extending in the axial direction, and a main movable portion that linearly moves in the axial direction by rotation of the lead screw, wherein the main movable portion is A composite linear actuator that operates as an electromagnetic linear actuator including a fixed portion and a sub-movable portion that linearly moves in the axial direction with respect to the sub-fixed portion by electromagnetic force, wherein the sub-fixed portion includes a yoke and a magnet. Wherein the auxiliary movable portion includes an air-core coil, and the auxiliary movable portion is linearly movable with respect to the auxiliary fixed portion via an upper leaf spring and a lower leaf spring. In the actuator,
A composite linear actuator, wherein the upper leaf spring and the lower leaf spring have the same shape. Constituting a composite linear actuator, in an electromagnetic linear actuator having a sub-fixed portion and a sub-movable portion, a spring member for supporting the sub-movable portion linearly movable with respect to the sub-fixed portion,
A spring member having an upper leaf spring and a lower leaf spring having the same shape.

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