JPH0759154B2 - Actuator - Google Patents
ActuatorInfo
- Publication number
- JPH0759154B2 JPH0759154B2 JP59018456A JP1845684A JPH0759154B2 JP H0759154 B2 JPH0759154 B2 JP H0759154B2 JP 59018456 A JP59018456 A JP 59018456A JP 1845684 A JP1845684 A JP 1845684A JP H0759154 B2 JPH0759154 B2 JP H0759154B2
- Authority
- JP
- Japan
- Prior art keywords
- displacement
- electrostrictive element
- carriage
- group
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000006073 displacement reaction Methods 0.000 claims description 30
- 230000006835 compression Effects 0.000 claims description 2
- 238000007906 compression Methods 0.000 claims description 2
- 229910000831 Steel Inorganic materials 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- 101000606504 Drosophila melanogaster Tyrosine-protein kinase-like otk Proteins 0.000 description 5
- 239000000126 substance Substances 0.000 description 4
- 230000010287 polarization Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/02—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing linear motion, e.g. actuators; Linear positioners ; Linear motors
- H02N2/021—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing linear motion, e.g. actuators; Linear positioners ; Linear motors using intermittent driving, e.g. step motors, piezoleg motors
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
Description
【発明の詳細な説明】 〔発明の技術分野〕 本発明は、デイスク記憶装置などに用いるアクチユエー
ターに関するものである。TECHNICAL FIELD OF THE INVENTION The present invention relates to an actuator used in a disk storage device or the like.
従来磁気デイスク装置のように同心円状に多数の情報ト
ラツクを有する記憶装置においては、情報の読出し・書
込みを行なうために磁気ヘツドを所定の位置に移動させ
る必要があり、その手段としてステツプモーターやボイ
スコイルモーターを用いてアクチユエーターを構成して
いた。一般に、トラツク密度の低い（すなわちトラツク
ピツチの広い）装置では制御が簡単で価格の安いステツ
プモーターが、トラツク密度の高い（すなわちトラツク
ピツチの狭い）装置ではアナログ制御の可能なボイスコ
イルモーターが使用される傾向にあつたが、これは、ス
テツプモーターでは基本的にデジタル的な位置送りしか
できないために装置の温度上昇に伴う微小なトラツクの
位置ずれ（オフトラツク）を補正できないことに起因す
る。すなわち、高トラツク密度の装置では、微小なオフ
トラツクが問題となるためアナログ制御の可能なボイス
コイルモーターを使う必要があつた。In a storage device having a large number of concentric information tracks, such as a conventional magnetic disk device, it is necessary to move a magnetic head to a predetermined position in order to read / write information. An actuator was constructed using a coil motor. In general, low-density (ie, wide-track) devices tend to use step motors that are easy to control and inexpensive, and high-density (ie, narrow-track) devices tend to use analog-controllable voice coil motors. As a matter of fact, this is because the step motor can basically only perform digital position feed, so that it is not possible to correct a minute track position deviation (off-track) due to a temperature rise of the apparatus. That is, in a device with a high track density, a minute off-track becomes a problem, so it is necessary to use a voice coil motor capable of analog control.
しかし、アナログ制御を行なうためにはデジタル制御に
比較して必然的に回路規模が大きくなり、アクチユエー
ター系の価格が上昇する欠点があつた。However, in order to perform analog control, the circuit scale inevitably becomes large as compared with digital control, and there is a drawback that the price of the actuator system rises.
本発明は、このような事情に鑑みてなされたもので、そ
の目的は、簡単な構成でしかも高精度の位置送りが可能
なアクチユエーターを提供することにある。The present invention has been made in view of such circumstances, and an object thereof is to provide an actuator having a simple structure and capable of highly accurate position feeding.
このような目的を達成するために、本発明は、ステツプ
モーターを用いた送り機構に厚み変位形の電歪素子を付
加して準アナログ的な位置送りを可能にしたものであ
る。以下、図示する実施例を用いて本発明を詳細に説明
する。In order to achieve such an object, the present invention provides a quasi-analog position feed by adding a thickness displacement type electrostrictive element to a feed mechanism using a step motor. Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
第１図は本発明の一実施例を示す構成図であり、１はス
テツプモーター、２はキヤリツジ、３はベアリング、４
はキヤリツジ走行レール、５はヘツド、６は媒体円板、
７はスチールベルト、８は電歪素子である。FIG. 1 is a block diagram showing an embodiment of the present invention, in which 1 is a step motor, 2 is a carriage, 3 is a bearing, and 4 is a bearing.
Is a carriage running rail, 5 is a head, 6 is a medium disk,
Reference numeral 7 is a steel belt, and 8 is an electrostrictive element.
ステツプモーター１は、歩進信号によりモーターごとに
固定した一定の角度360゜/n（ｎは整数）ずつ回転し、
その回転はシヤフト９に巻付け固定されかつ一端がキヤ
リツジに固定されたスチールベルト７により直進運動に
変換される。スチールベルト７は、ばね部7aを介してＡ
端にてキヤリツジ２に固着される。直進運動方向は、ベ
アリング３および走行レール４により一方向に規制さ
れ、通常、ヘツド５が媒体円板６の回転半径方向に動く
ように設定される。The step motor 1 rotates by a fixed angle of 360 ° / n (n is an integer) fixed for each motor by a step signal,
The rotation is converted into a rectilinear movement by a steel belt 7 which is fixed by winding around a shaft 9 and one end of which is fixed to a carriage. The steel belt 7 is A through the spring portion 7a.
It is fixed to the carriage 2 at the end. The linear movement direction is restricted to one direction by the bearing 3 and the traveling rail 4, and normally, the head 5 is set so as to move in the rotation radius direction of the medium disk 6.
ここで、オフトラツクに対し制御可能なアクチユエータ
ーを得るためには、ヘツドの取付部10とステツプモータ
ー１との間に何らかの微小移動機構を設ければよく、従
来からも例えばキヤリツジ２上に小形のボイスコイルモ
ーターを搭載し当該ボイスコイルモーターでヘツドを微
小移動させる方法やバイモルフ素子をボイスコイルモー
ターの代用とする方法などが考えられていたが、これら
の方法では構成が複雑となりかつアナログ制御回路を必
要とする。Here, in order to obtain an actuator that can be controlled with respect to off-track, a micro-moving mechanism of some kind may be provided between the head mounting portion 10 and the step motor 1. Conventionally, for example, a small mount on the carriage 2 can be used. The following methods have been considered: a voice coil motor is installed and the head is moved minutely by the voice coil motor, or a bimorph element is used as a substitute for the voice coil motor. However, with these methods, the configuration becomes complicated and the analog control circuit is used. Need.
このため本発明では、スチールベルト７の一端Ｂとキヤ
リツジへの固定端Ｃとの間に第２図に示すような厚み変
位形電歪素子８を介在させてスチールベルト７をキヤリ
ツジ３に固定させ、当該電歪素子８をデジタル駆動する
ことにより準アナログ的な微小変位を得る。Therefore, in the present invention, the thickness displacement type electrostrictive element 8 as shown in FIG. 2 is interposed between one end B of the steel belt 7 and the fixed end C to the carriage to fix the steel belt 7 to the carriage 3. A quasi-analog minute displacement is obtained by digitally driving the electrostrictive element 8.
電歪素子８は、第２図に示したように均一な厚さ（0.05
〜0.3mm）のPZT,PCM等の強誘電体11を個々の層ごとに電
圧印加できるように電極12a,12bを付し、絶縁層13を介
して多数積層したものである。強誘電体11は、複数（図
示の例では３つ）の群に分けられ、各群内の強誘電体11
は同一電位に対し同一方向の厚み変位（伸び）を生じる
ように並列接続されている。すなわち、各強誘電体11の
一方の電極12bは共通の接地端子に接続されているが、
他方の電極12aは、各群ごとに、図示しない電源端子に
接続される。各群の層数は、図示の例ではＩ群がｍ、II
群が2m、III群が4m（図示の例ではｍ＝３）としてあ
る。なお、強誘電体11の分極方向が交互に逆向きとなる
ように配置し、かつ電極の極性が交互に逆極性となるよ
うに構成したものでも同様な変位が得られることはいう
までもない。The electrostrictive element 8 has a uniform thickness (0.05 mm) as shown in FIG.
.About.0.3 mm) PZT, PCM or other ferroelectric substance 11 is provided with electrodes 12a and 12b so that a voltage can be applied to each layer, and a large number are laminated with an insulating layer 13 interposed therebetween. The ferroelectrics 11 are divided into a plurality (three in the illustrated example) of groups, and the ferroelectrics 11 in each group are separated.
Are connected in parallel so as to generate a thickness displacement (elongation) in the same direction with respect to the same potential. That is, one electrode 12b of each ferroelectric 11 is connected to a common ground terminal,
The other electrode 12a is connected to a power supply terminal (not shown) for each group. In the illustrated example, the number of layers in each group is m, II for group I.
The group is 2 m and the group III is 4 m (m = 3 in the illustrated example). It is needless to say that the same displacement can be obtained even in the case where the ferroelectric bodies 11 are arranged so that the polarization directions thereof are alternately opposite and the polarities of the electrodes are alternately opposite. .
個々の強誘電体の電圧−変位特性は、周知のように第３
図に例示するようないわゆるバタフライ曲線となるが、
分極方向に一定電圧V1をオン・オフ印加する場合にはそ
の非線形特性は考慮する必要がなく、単に変位△の変化
となる。すなわち、Ｉ群はオン時に△ｍ、II群は２△
ｍ、III群は４△ｍの変位を生ずることとなり、I,II,II
I群を任意に選択駆動することにより最小変位間隔△ｍ
で８（＝23）×△ｍの変位がデジタル的に制御可能とな
る。この場合、△ｍが位置ずれの許容範囲（例えば±１
μｍ）内であれば、このデジタル制御によりほぼ完全な
オフトラツクに対する制御が行なえ、アナログ的移動機
構は不要である。As is well known, the voltage-displacement characteristic of each ferroelectric is the third.
Although it becomes a so-called butterfly curve as illustrated in the figure,
When the constant voltage V 1 is applied on / off in the polarization direction, it is not necessary to consider the non-linear characteristics, and the displacement Δ simply changes. That is, Group I is Δm when turned on, Group II is 2Δ.
Displacement of 4Δm occurs in the m and III groups, and I, II, II
Minimum displacement interval Δm by selectively driving group I
With this, a displacement of 8 (= 2 3 ) × Δm can be digitally controlled. In this case, Δm is the allowable range of positional deviation (for example, ± 1
.mu.m), almost complete off-track control can be performed by this digital control, and an analog moving mechanism is unnecessary.
各群に与える電圧は、群を構成する強誘電体11の厚みが
均一であるために同一でよく、この点においてもデジタ
ル回路構成のみで実現可能である。また、厚み方向変位
を利用する場合負荷力が大きいことも周知の通りであ
り、ステツプモーターの駆動によつて生じる衝撃力によ
り素子自体が変形することが少ないことも、ボイスコイ
ルモーターやバイモルフ素子を用いたものでは得られな
い利点である。The voltage applied to each group may be the same because the thickness of the ferroelectric substance 11 forming the group is uniform, and in this respect as well, it can be realized only by the digital circuit configuration. In addition, it is well known that the load force is large when using the displacement in the thickness direction, and the element itself is less likely to be deformed by the impact force generated by driving the step motor. This is an advantage that cannot be obtained with the one used.
しかしながら、第３図から明らかなように電圧を0Vから
＋V1（分極方向を正とする）Ｖまで変化させるのみでは
得られる変位量が小さいため、一般には正負の制御され
た電圧を切換え印加し、強誘電体の歪量（ひいては変位
量）を大きくする必要がある。しかし、その場合には、
単純なオン・オフ切換えの論理回路に比較して回路構成
が複雑となる欠点がある。However, as is clear from FIG. 3, the amount of displacement obtained by only changing the voltage from 0 V to + V 1 (the polarization direction is positive) V is small, so in general, a positive and negative controlled voltage is switched and applied. , It is necessary to increase the strain amount (and thus the displacement amount) of the ferroelectric substance. But in that case,
There is a drawback that the circuit configuration becomes complicated as compared with a simple on / off switching logic circuit.
そこで、本発明ではばね部7aにより印加されるスチール
ベルト７の張力を利用して、電歪素子８に上記変位方向
とは逆（圧縮）方向の歪を与える。この結果、電圧を印
加しない状態で、電歪素子８の圧電効果により発生した
負の電圧が自動的にバイアスされるため、正電圧V2（＝
V1）のオン・オフにより大きな歪量が得られる。すなわ
ち、強誘電体11自体の変位量は、応力を印加しないとき
の△から、応力印加によつてより大きな△′となる。Therefore, in the present invention, the tension of the steel belt 7 applied by the spring portion 7a is utilized to give the electrostrictive element 8 strain in the direction opposite to the displacement direction (compression). As a result, the negative voltage generated by the piezoelectric effect of the electrostrictive element 8 is automatically biased without applying the voltage, so that the positive voltage V 2 (=
Large distortion can be obtained by turning V 1 ) on and off. That is, the amount of displacement of the ferroelectric substance 11 itself changes from Δ when no stress is applied to Δ ′ which is larger when stress is applied.
なお、上述したような電歪素子８を、本発明とは異なり
例えばキヤリツジ２上に配置してヘッド取付部10を変位
させるようにした場合でも、準アナログ的な微動は可能
となるが、上記説明のようにばね部7aを利用した応力印
加による変位量の拡大は望めない。Unlike the present invention, the electrostrictive element 8 as described above is arranged on the carriage 2 and the head mounting portion 10 is displaced, so that the quasi-analog fine movement can be performed. As described above, the amount of displacement cannot be expected to increase by applying stress using the spring portion 7a.
以上、オフトラツク分の微小移動を対象として説明した
が、電歪素子８の最大可能変位量をステツプモーターに
よる１送りピツチ以上に設定すれば、当該１送りピツチ
内の任意の位置にヘツド位置を設定することが可能とな
るため、１送りピツチの中でさらに多くのトラツクに分
割して記憶媒体を有効利用することも可能となる。Although the above description has been made with respect to the minute movement for the off-track, if the maximum possible displacement amount of the electrostrictive element 8 is set to one feed pitch or more by the step motor, the head position is set to an arbitrary position within the one feed pitch. Therefore, the storage medium can be effectively used by dividing into more tracks in one feed pitch.
なお、デジタル微動を行ない得る電歪素子としてすべり
変位を利用した横方向変位形のものが米国特許第3,153,
229号等の公知であるが、横方向変位形電歪素子の場
合、電圧感度を高めるためには素子の厚みが薄くなけれ
ばならないことから機械的衝撃に弱くなる欠点がある。
これに対し、本発明に用いた厚み変位形では素子の厚み
は設計により自由に変化できるため信頼性の高いものが
得られる。Incidentally, a lateral displacement type utilizing a sliding displacement as an electrostrictive element capable of performing digital fine movement is a U.S. Pat.
As is well known, such as No. 229, the lateral displacement type electrostrictive element has a drawback that it is weak against mechanical shock because the element must be thin in order to increase voltage sensitivity.
On the other hand, in the thickness displacement type used in the present invention, since the thickness of the element can be freely changed by design, a highly reliable element can be obtained.
以上説明したように、本発明によれば、最小変位の任意
の整数倍の変位量が得られるように複数の群に分割した
強誘電体の積層構造からなる厚み変位形電歪素子を、圧
縮方向の力を加えて歪量を増大させた状態でベルトとキ
ヤリツジとの間に介在させたことにより、当該電歪素子
をデジタル的に微動させることによつて準アナログ的な
精密な位置決めが行なえる。しかも、アナログ回路を必
要としないため、回路構成は簡単で低価格化が図れる利
点である。As described above, according to the present invention, the thickness displacement electrostrictive element composed of the laminated structure of the ferroelectric material divided into a plurality of groups so as to obtain the displacement amount of any integral multiple of the minimum displacement is compressed. By interposing between the belt and the carriage in a state in which the amount of strain is increased by applying the force in the direction, the electrostrictive element can be finely moved digitally for precise quasi-analog positioning. It Moreover, since an analog circuit is not required, the circuit configuration is simple and the cost can be reduced.
第１図は本発明の一実施例を示す構成図、第２図は電歪
素子の構成例を示す斜視図、第３図は電歪素子の電圧−
変位特性の一例を示す図である。 １……ステツプモーター、２……キヤリツジ、３……ベ
アリング、４……キヤリツジ走行レール、５……ヘツ
ド、６……媒体円板、７……スチールベルト、7a……ば
ね部（張力発生部）、８……電歪素子、９……シヤフ
ト、10……ヘツド取付部、11……強誘電体、12a,12b…
…電極、13……絶縁層。FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a perspective view showing a configuration example of an electrostrictive element, and FIG.
It is a figure which shows an example of a displacement characteristic. 1 ... Step motor, 2 ... Carriage, 3 ... Bearing, 4 ... Carriage running rail, 5 ... Head, 6 ... Medium disc, 7 ... Steel belt, 7a. ), 8 ... Electrostrictive element, 9 ... Shaft, 10 ... Head mounting part, 11 ... Ferroelectric material, 12a, 12b ...
… Electrodes, 13… Insulating layers.
Claims (1)
よりキヤリツジの直進送り運動に変換するアクチユエー
ターにおいて、ベルトの一端とキヤリツジとの間に、そ
れぞれ電圧印加が可能な複数の均一な厚さの強誘電体を
絶縁層を介して積層するとともに当該強誘電体を複数の
群に分けかつ各群内の強誘電体をそれぞれ同一電位に対
して同一方向の変位を生じるように並列接続してなる厚
み変位形電歪素子を固定し、上記群分けは、各群に選択
的に電圧を印加することにより最小変位の任意の整数倍
の変位量が得られるような強誘電体数比で行なうととも
に、上記厚み変位形電歪素子に対し圧縮方向の力を加え
てなるアクチユエーター。1. An actuator for converting the shaft rotational movement of a step motor into a linear feed movement of a carriage by means of a belt, and a plurality of uniform thicknesses to which a voltage can be applied between one end of the belt and the carriage. Ferroelectrics are laminated via an insulating layer, the ferroelectrics are divided into a plurality of groups, and the ferroelectrics in each group are connected in parallel so as to generate displacement in the same direction with respect to the same potential. The thickness displacement type electrostrictive element is fixed, and the grouping is performed with a ferroelectric number ratio such that a displacement amount of an arbitrary integral multiple of the minimum displacement can be obtained by selectively applying a voltage to each group. , An actuator that applies a force in the compression direction to the thickness displacement type electrostrictive element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59018456A JPH0759154B2 (en) | 1984-02-06 | 1984-02-06 | Actuator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59018456A JPH0759154B2 (en) | 1984-02-06 | 1984-02-06 | Actuator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60174075A JPS60174075A (en) | 1985-09-07 |
| JPH0759154B2 true JPH0759154B2 (en) | 1995-06-21 |
Family
ID=11972129
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59018456A Expired - Lifetime JPH0759154B2 (en) | 1984-02-06 | 1984-02-06 | Actuator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0759154B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0817020B2 (en) * | 1986-01-29 | 1996-02-21 | 株式会社日立製作所 | Disk drive head moving mechanism |
| JPH0787025B2 (en) * | 1987-09-07 | 1995-09-20 | 旭光学工業株式会社 | Disk drive carriage drive |
| JPH0239371U (en) * | 1988-09-07 | 1990-03-16 |
-
1984
- 1984-02-06 JP JP59018456A patent/JPH0759154B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60174075A (en) | 1985-09-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |