JP3721702B2 - Rotation drive mechanism and disk device - Google Patents

Description

【００３３】
【数２】

【００３４】
このとき、各バランス球２０、２０、・・・の全体の重心は、回転中心を介して上記アンバランス方向に対向する位置であって、その対向線上に位置している。
【００３５】
この状態では、記録ディスク１のアンバランスにより回転中心からずれたケース体１１と各バランス球２０、２０、・・・との全体の重心は、合成回転体の回転軸上に位置している。
【００３６】
このように、各バランス球２０、２０、・・・はアンバランスを有する記録ディスク１が回転された場合、所謂自動調心作用により自己が適宜に移動し、これにより、合成重心の位置が回転軸上に位置する。従って、合成回転体は振動することなく回転し、従って、アンバランスを有する記録ディスク１をその重心を回転軸上に位置させた状態で回転させることができる。
【００３７】
このような自動調心作用は、合成回転体の回転周波数がダンパ６、６、・・・の共振周波数（合成回転体の回転軸に垂直な面（図１中のｘ，ｙ平面）内の方向についての共振周波数）以上となったときに、効果的に発生する。即ち、高速度で情報信号の記録または再生を行う記録ディスクについては、効果的に発生させることができる。
【００３８】
尚、上記した回転駆動機構９においては、ケース体１１の停止時において各バランス球２０、２０、・・・が互いに等角度間隔に配置されているため、ケース体１１の回転の開始時において、各バランス球２０、２０、・・・によってアンバランスの原因が生じることはない。
【００３９】
従って、上記のように、バランス球２０、２０、・・・を備えた回転駆動機構９によって、重量的なアンバランスを有する記録ディスク１を回転させても合成回転体に振動を生ずることがない。即ち、ディスクドライブ装置２においては、重量的なアンバランスを有する記録ディスク１の信号記録面に対して良好に情報信号の書き込み又は読み出しができる。
【００４０】
このようにして記録ディスク１が回転されると、光学ピックアップ装置４は記録ディスク１にレーザ光を照射し、その反射光を受光して検出する。光学ピックアップ装置４はガイドシャフト７、７に沿って移動されることにより、支軸１０に対する離接方向、即ち、ディスクテーブル１２に装着された記録ディスク１の半径方向に移動され、記録ディスク１の内外周に亘って移動される。そして、光学ピックアップ装置４によって、記録ディスク１に対する情報信号の書き込み又は読み出しが行われる。
【００４１】
ところで、回転駆動機構９においては、スピンドルモータ３の起動時、即ち、ケース体１１が停止状態から回転を開始するときにおいては、各バランス球２０、２０、・・・がケース体１１に対して相対移動することなく、同期して起動されたほうが自動調心作用の効果を迅速に得ることができる。即ち、図７に示すように、ケース体１１の回転速度と各バランス球２０、２０、・・・の回転速度との差は、少なくともケース体１１の回転速度が使用回転域（ダンパ６、６、・・・の共振周波数以上の回転周波数）に達したときには、０となっていることが望ましい。
【００４２】
ここで、ケース体１１の起動時に各バランス球２０、２０、・・・がケース体１１に対して相対移動せずに同期して起動する条件は、次のようになる。即ち、ケース体１１からバランス球２０、２０、・・・に対して伝達される回転トルクを伝達トルクＴ₀とし、バランス球２０、２０、・・・の慣性モーメントをＪとし、バランス球２０、２０、・・・の回転角加速度をβとして、起動トルクＴ₁＝Ｊ・βとおく。そして、バランス球２０、２０、・・・の質量をｍとし、回転軸よりバランス球２０、２０、・・・までの距離をＲとして、Ｔ₂＝ｍ・Ｒとおく。すると、ケース体１１が停止状態より回転を開始するときに、図８に示すように、
Ｔ₁＋Ｔ₂＜Ｔ₀
が成立していれば、支軸１０の方向（傾き）に依らずに、各バランス球２０、２０、・・・はケース体１１の起動に同期して起動される（尚、支軸１０の軸方向を鉛直として使用する場合のみを考えるならば、Ｔ₁＜Ｔ₀が成立していればよい。）。
【００４３】
そして、ケース体１１の回転周波数がダンパ６、６、・・・の共振周波数（ケース体１１の回転軸に垂直な面内の方向についての共振周波数）以上となったときには、バランス球２０、２０、・・・をケース体１１に対して該ケース体１１の回転軸回りの周方向に移動させるトルクとしてバランス球２０、２０、・・・に働くトルクを調整トルクＴ₃としたとき、図８に示すように、
Ｔ₀＜Ｔ₃
が成立している必要がある。この条件が成立していないと、自動調心が行われない。ここで、ケース体１１からバランス球２０、２０、・・・に対して伝達される回転トルクを伝達トルクＴ₀がケース体１１の回転速度に依らずに一定の場合には、
Ｔ₁＋Ｔ₂＜Ｔ₀＜Ｔ₃
が成立している必要がある。従って、伝達トルクＴ₀は、低回転速度域において大きく、高回転速度域（使用回転域ω、ω₁≦ω≦ω₂）において小さくなるようにしておけば、上述の条件を満足し易くなる。
【００４４】
上記した回転駆動機構９においては、各バランス球２０、２０、・・・は、ケース体１１が停止状態より回転を開始するときには、バランス球２０、２０、・・・がマグネット２２側に吸引されていることに起因してケース体１１より各バランス球２０、２０、・・・に伝達される起動トルクによってケース体１１に追従してこのケース体１１と共に回転を開始する。即ち、各バランス球２０、２０、・・・は、ケース体１１の停止時において、マグネット２２の外周囲部に吸着されており、このときのバランス球２０、２０、・・・とマグネット１２の外周囲部との間の転がり摩擦係数をμ₁とすると、ケース体１１よりバランス球２０、２０、・・・に伝達される伝達トルクＴ₀は、
Ｔ₀＝μ₁・ｆ₁・ｒ₁
となる。そして、起動時の角加速度をβとした場合の起動トルクＴ₁は、
Ｔ₁＝ｍ・ｒ₁ ²・β
となる。Ｔ₁＜Ｔ₀であることが必要なので、
ｍ・ｒ₁ ²・β＜μ₁・ｆ₁・ｒ₁
ｍ・ｒ₁・β＜μ₁・ｆ₁
となる。また、バランス球２０、２０、・・・中にマグネット２２により発生された磁束が通過していることによる磁気抵抗も、伝達トルクＴ₀を増加させる作用をする。
【００４５】
そして、支軸１０を水平にした場合のバランス球２０、２０、・・・の自重、及び、使用回転域ω（ω₁≦ω≦ω₂）においてバランス球２０、２０、・・・がマグネット２２より遠心力により離間されなければならないことを考慮すると、
ｍ・ｇ＜ｆ₁＜ｍ・ｒ₁・ω₁ ²−ｍ・ｇ（但し、ｇは重力加速度）
が成立している必要がある。この条件により、各バランス球２０、２０、・・・は、ケース体１１が高速回転されたときには、遠心力によりマグネット２２の外周囲部より離間する。このとき、伝達トルクＴ₀が減少して、自動調心が行われるための条件が満足され易くなる。即ち、バランス球２０、２０、・・・と移動空間１１ａの外側内周面２１との間の転がり摩擦係数をμ₂とすると、バランス球２０、２０、・・・が外側内周面２１に当接しているときの伝達トルクＴ₀は、
Ｔ₀＝μ₂・ｒ₂（ｍ・ｒ₂・ω₂ ²−ｆ₂＋ｍ・ｇ）
であり、この伝達トルクＴ₀が、調整トルクＴ₃よりも小さくなっていればよい。また、ケース体１１の回転速度が使用回転域よりも低速となったときに、各バランス球２０、２０、・・・が再びマグネット２２の外周囲部に吸着されるためには、
ｍ・ｇ＜ｆ₂＜ｍ・ｒ₂・ω₁ ²−ｍ・ｇ
が満足される必要がある。
【００４６】
尚、調心作用は、図７に示すように、バランス球２０、２０、・・・がケース体１１と同期して回転されているときに行われ、ケース体１１が停止状態から回転を開始するときにおいては、各バランス球２０、２０、・・・がケース体１１に対して相対移動することなく、同期して起動されたほうが自動調心作用の効果を迅速に得ることができる。従って、バランス球２０、２０、・・・は使用回転数に達するまでは遠心力に抗してできるだけ長時間マグネット２２に吸着されていることが望ましく、これを達成するためにはマグネット２２の磁力を大きくする必要がある。
【００４７】
マグネット２２の磁力を大きくするための手段として、マグネット２２を大型化することが考えられるが、マグネット２２を大型化してしまうと、その分回転駆動機構が大型化し、延いてはディスクドライブ装置が大型となってしまう。
【００４８】
そこで、上記した回転駆動機構９にあっては、ヨーク２３、２３をマグネット２２の上下に配置して該マグネット２２による吸着力を高めているため、ケース体１１が回転されたときにバランス球２０、２０、・・・が長時間吸着され、該バランス球２０、２０、・・・が遠心力によってマグネット２２から離間されるときにその回転がケース体１１の回転に同期して行われている確率が高い。
【００４９】
従って、その分マグネット２２を薄型化することが可能となり、これによりディスクドライブ装置２の薄型化を図ることができる。
【００５０】
また、バランス球２０、２０、・・・が遠心力によりマグネット２２から離れた後において、調心作用を迅速に実行させるようにするためには、バランス球２０、２０、・・・のケース体１１に対する相対的な回転が、抵抗のない状態で行われるようにしておく必要がある。即ち、バランス球２０、２０、・・・のケース体１１に対する回転に伴ってバランス球２０、２０、・・・とケース体１１との間に生ずる摩擦力は小さいことが望ましい。
【００５１】
そこで、上記した回転駆動機構９にあっては、バランス部材として球状体であるバランス球２０、２０、・・・を用い、バランス球２０、２０、・・・とケース体１１の内面との間に生じる摩擦力を小さくしている。
【００５２】
従って、バランス球２０、２０、・・・がマグネット２２から離れた後に該バランス球２０、２０、・・・のケース体１１に対する相対的な回転が抵抗の小さい状態で行われ、調心作用が迅速に実行される。
【００５３】
上記にはマグネット２２を移動空間１１ａの中央部に設けたものを示したが、マグネット２２Ａを移動空間１１ａの外周部に設けるようにしてもよい（図９及び図１０参照）。
【００５４】
このようにマグネット２２Ａを移動空間１１ａの外周部に設けた場合には、各バランス球２０、２０、・・・は、ケース体１１の回転速度に依らず、常に、マグネット２２Ａの内周面２２ａに接していることになるが、バランス球２０、２０、・・・がマグネット２２Ａの内周面２２ａに沿って移動されることにより、自動調心作用を発生する（図１０参照）。
【００５５】
また、上記にはケース体１１に各バランス部材を配置するものを示したが、各バランス部材が配置される移動空間１１ａを、図１１に示すように、ディスクテーブル１２Ａ内に形成してもよい。そして、この場合にはディスクテーブル１２Ａがケース体としての機能を有する。
【００５６】
このように移動空間１１ａをディスクテーブル１２Ａ内に形成すれば、各バランス部材を配置するための別部材としてのケース体１１を設ける必要がなく、回転駆動機構の部品点数が少なくなり、コストの低減に寄与する。
【００５７】
また、図１２に示すように、ディスクテーブルではなく、移動空間１１ａをチャッキング部材２４内に形成してもよい。そして、この場合にはチャッキング部材２４がケース体としての機能を有する。
【００５８】
このように移動空間１１ａをチャッキング部材２４内に形成すれば、ディスクテーブル１２Ａ内に移動空間１１ａを形成した場合と同様に、各バランス部材を配置するための別部材としてのケース体１１を設ける必要がなく、回転駆動機構の部品点数が少なくなり、コストの低減に寄与する。
【００５９】
尚、上記した実施の形態においては、アンバランスを有する記録ディスク１をディスクテーブルに装着したときに、合成回転体に対して自動調心作用を実行させる例を示したが、合成回転体のうちの記録ディスク１以外の部材がアンバランスを有する場合においても、回転駆動機構９によって自動調心作用を実行させて回転時の振動を抑制することができる。
【００６０】
また、上記した実施の形態においては、本発明を光ディスクや光磁気ディスクの如き記録ディスクに対する再生や記録を行うディスクドライブ装置に適用したものを説明したが、本発明は、産業用機械や他の電化製品に適用することもできる。
【００６１】
【発明の効果】
以上に記載したところから明らかな通り、本発明回転駆動機構及び回転駆動機構を備えたディスク装置にあっては、回転駆動手段により支軸を介して回転されるケース体と、該ケース体に形成され軸方向に直交する方向の断面形状が円環状を為す移動空間と、磁性材料により形成されケース体に接触すると共に移動空間内に移動可能に配設されたバランス部材と、移動空間内の中心部に配設されバランス部材を吸着するマグネットと、移動空間内に配設されるヨークとを備え、ケース体の非回転時にはマグネットの外周部に上記バランス部材が吸着されており、ケース体の回転時には遠心力により上記バランス部材が上記マグネットの外周部から離間され、バランス部材がケース体の回転に伴って回転されて、回転駆動手段によって回転する部材の合成重心が回転軸上に位置するようにしたので、または、回転駆動手段により支軸を介して回転されるケース体と、該ケース体に形成され軸方向に直交する方向の断面形状が円環状を為す移動空間と、磁性材料により形成されケース体に接触すると共に移動空間内に移動可能に配設されたバランス部材と、移動空間内の外周部に配設されバランス部材を吸着するマグネットと、移動空間内に配設されるヨークとを備え、ケース体の非回転時にはマグネットの内周部にバランス部材が吸着されており、ケース体の回転時にはバランス部材がマグネットの内周部に吸着された状態で周方向に移動され、バランス部材がケース体の回転に伴って回転されて、回転駆動手段によって回転する部材の合成重心が回転軸上に位置するようにしたので、合成回転体は振動を生じさせることなく回転することができ該回転が回転中心の偏心を生じない状態で為されると共に、移動空間内にヨークが設けられているためマグネットによる吸着力が高まり、その分マグネットを薄型化することができ、回転駆動機構の小型化に寄与する。
【００６２】
請求項２に記載した発明にあっては、マグネットは移動空間の中心部に位置され、バランス部材は球状体として形成され、ケース体の非回転時にはマグネットの外周部に球状体が吸着されており、ケース体の回転時には遠心力により球状体がマグネットの外周部から離間されるようにしたので、ケース体が停止状態より回転を開始するときに該ケース体から起動トルクが伝達されバランス部材がケース体に追従し該ケース体と共に回転を開始し、自動調心作用が迅速に実行される。
【００６３】
請求項３に記載した発明にあっては、マグネットは移動空間の外周部に位置され、バランス部材は球状体として形成され、ケース体の非回転時にはマグネットの内周部に球状体が停止された状態で吸着されており、ケース体の回転時には球状体がマグネットの内周部に吸着された状態で周方向に移動されるようにしたので、ケース体が停止状態より回転を開始するときに該ケース体から起動トルクが伝達されバランス部材がケース体に追従し該ケース体と共に回転を開始し、自動調心作用が迅速に実行される。
【００６４】
尚、上記した実施の形態において示した各部の具体的な形状及び構造は、何れも本発明を実施するに際しての具体化のほんの一例を示したものにすぎず、これらによって本発明の技術的範囲が限定的に解釈されることがあってはならないものである。
【図面の簡単な説明】
【図１】 図２乃至図８と共に本発明回転駆動機構及び回転駆動機構を備えたディスク装置の実施の形態を示すものであり、本図は回転駆動機構を備えるディスクドライブ装置を示す概略斜視図である。
【図２】 ケース体を示す拡大水平断面図である。
【図３】 合成回転体を示す拡大縦断面図である。
【図４】 ケース体が回転された状態を示す拡大水平断面図である。
【図５】 ケース体が回転された状態を示す拡大縦断面図である。
【図６】 自動調心作用が実行された状態を示すケース体の拡大水平断面図である。
【図７】 回転駆動機構において、ケース体及びバランス部材の回転速度の変化を示すグラフである。
【図８】 回転駆動機構において、ケース体からバランス部材に伝達される回転トルクの変化を示すグラフである。
【図９】 図１０と共に回転駆動機構の別の形態を示すものであり、本図は自動調心作用が実行される前の状態を示すケース体の拡大水平断面図である。
【図１０】 自動調心作用が実行された状態を示すケース体の拡大水平断面図である。
【図１１】 ケース体の別の形態を示す拡大縦断面図である。
【図１２】 ケース体のさらに別の形態を示す拡大縦断面図である。
【符号の説明】
２…ディスクドライブ装置（ディスク装置）、３…スピンドルモータ（回転駆動手段）、９…回転駆動機構、１０…支軸、１１…ケース体、１１ａ…移動空間、２０…バランス球（バランス部材）、２２…マグネット、２３…ヨーク、１２Ａ…ディスクテーブル（ケース体）、２２Ａ…マグネット、２４…チャッキング部材（ケース体）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary drive mechanism and a disk device including the rotary drive mechanism . Specifically, by moving the balance member with respect to the case body, the rotation performed by the rotation driving means is performed in a state where the eccentricity of the rotation center does not occur, and the magnet disposed in the moving space is thin. The technology relates to
[0002]
[Prior art]
For example, in a disk drive device that is provided in a computer and performs reproduction and recording on a recording disk such as an optical disk or a magneto-optical disk, the recording disk is rotated by a rotation drive mechanism. This rotational drive mechanism has a spindle motor as rotational drive means and a disk table that is fixed to the tip end side of the spindle shaft of the spindle motor and holds the central portion of the recording disk. The recording disk rotated by such a rotation driving mechanism records and / or reproduces information signals by an optical pickup or a magnetic head device.
[0003]
[Problems to be solved by the invention]
By the way, a recording disk such as the above-described optical disk may cause a weight imbalance when manufactured. When a recording disk having such a weight imbalance is rotated by a rotation drive mechanism, the recording center vibrates with the disk table because the center of rotation does not coincide with the center of gravity. Due to this vibration, focusing and tracking with respect to the signal recording surface of the recording disk by the optical pickup device and tracking of the recording track of the recording disk by the magnetic head device cannot be performed satisfactorily.
[0004]
In general, the amount of imbalance that occurs in a recording disk varies depending on the recording disk.
[0005]
Furthermore, recently, it has become possible to record or reproduce data on a recording disk at a high speed, and there is also a problem that the vibration of the recording disk increases as the rotational speed increases.
[0006]
Therefore, if there is no vibration suppression means that can respond at any time according to the amount of weight imbalance or the rotational speed for each recording disk, the vibration of the recording disk cannot be suppressed.
[0007]
Accordingly, the rotation drive mechanism and the disk device provided with the rotation drive mechanism of the present invention overcome the above-described problems, and allow the rotation performed by the rotation drive means to be performed in a state where no eccentricity of the rotation center occurs. Is an issue.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, a rotary drive mechanism and a disk device provided with the rotary drive mechanism according to the present invention include a case body that is rotated by a rotary drive means via a support shaft, and an axial direction formed on the case body. A moving space in which the cross-sectional shape in the orthogonal direction forms an annular shape, a balance member formed of a magnetic material and in contact with the case body and arranged to be movable in the moving space, and arranged in the center of the moving space The balance member is attracted to the outer peripheral portion of the magnet when the case body is not rotating, and a centrifugal force is applied when the case body is rotated. the balance member is spaced from the outer peripheral portion of the magnet, and the balance member is rotated with the rotation of the case body, combined center of gravity of the member to be rotated by the rotary drive means Is obtained so as to be positioned on guinea. Alternatively, a case body that is rotated by a rotation driving means via a support shaft, a moving space that is formed in the case body and has a cross-sectional shape in a direction perpendicular to the axial direction, and a case body that is formed of a magnetic material. A case that includes a balance member that is in contact with and movable in the movement space; a magnet that is disposed on an outer periphery of the movement space and that attracts the balance member; and a yoke that is disposed in the movement space. When the body is not rotating, the balance member is attracted to the inner periphery of the magnet. When the case is rotating, the balance member is moved in the circumferential direction while being attracted to the inner periphery of the magnet. The combined center of gravity of the member rotated by the rotation and rotated by the rotation driving means is positioned on the rotation axis.
[0009]
Therefore, in the disk drive equipped with the rotation drive mechanism and the rotation drive mechanism of the present invention, the balance member is rotated along with the rotation of the case body and moves with respect to the case body and is rotated by the rotation drive means. The center of gravity (synthetic center of gravity) of the rotating member (synthetic rotating body) included in the rotation driving means is positioned on the rotation axis.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a rotary drive mechanism and a disk device having a rotary drive mechanism according to the present invention will be described below with reference to the accompanying drawings. In the embodiment described below, the present invention is applied to a disk drive device that performs reproduction and recording on a recording disk such as an optical disk or a magneto-optical disk.
[0011]
The recording disk 1 is configured by forming a signal recording surface on a transparent substrate formed in a disk shape having a diameter of 120 mm by a synthetic resin material such as polycarbonate. The recording disk 1 is provided with a circular opening (chucking hole) 1a at the center thereof. The recording disk 1 is positioned by fitting a positioning projection of a disk table, which will be described later, into the circular opening 1a.
[0012]
The disk drive device 2 includes a mechanical chassis 5 on which a spindle motor 3 and an optical pickup device 4 serving as rotational driving means are mounted, and a plurality of dampers 6, 6, which support the mechanical chassis 5 in a floating manner with respect to a base chassis (not shown). .. (see FIG. 1).
[0013]
The optical pickup device 4 is supported by the mechanical chassis 5 via guide shafts 7 and 7 so as to be movable in the radial direction of the recording disk 1 mounted on the disk table. The optical pickup device 4 includes a light source and a light detector (not shown) such as a laser diode, and irradiates the recording disk 1 with laser light emitted from the light source via the objective lens 8, and also records the laser light recording disk. The reflected light from 1 is detected by a photodetector.
[0014]
The rotary drive mechanism 9 is fixed to the upper end portion of the support shaft 10 in the same manner as the case body 11 fixed to the position near the upper end of the spindle motor 3 and the support shaft (spindle shaft) 10 rotated by the spindle motor 3. A disk table (turn table) 12 is provided (see FIG. 3).
[0015]
The support shaft 10 is supported by a motor substrate 13 fixed on the mechanical chassis 5 so as to be rotatable around an axis via rotation bearings 14 and 14. A motor rotor 15 constituting the spindle motor 3 is attached to the support shaft 10, and the motor rotor 15 is formed in a substantially cylindrical shape, and a drive magnet 16 is fixed to an inner surface portion. The drive magnet 16 faces the stator coil 17 fixed on the motor substrate 13.
[0016]
In the spindle motor 3, when a drive current is supplied to the stator coil 17, the magnetic field generated by the stator coil 17 acts on the drive magnet 16, and the drive magnet 16 and the motor rotor 15 are rotated together with the support shaft 10. Thereby, the case body 11 and the disk table 12 are rotated together. That is, the support shaft 10 is a drive shaft of the spindle motor 3.
[0017]
The disc table 12 is formed in a substantially disc shape, and is fixed to the support shaft 10 by press-fitting the tip end portion of the support shaft 10 into a support shaft press-fitting hole formed in the center portion. The disk table 12 is provided with a positioning projection 12a for positioning the recording disk 1 at the center thereof. The positioning protrusion 12a is provided so as to protrude in a substantially truncated cone shape, and is fitted into the circular opening 1a of the recording disk 1 to position the recording disk 1. In addition, a magnet is built in the positioning projection 12a, and a chucking member (clamper) (not shown) having a magnetic material is attracted. That is, the recording disk 1 is securely held while being sandwiched between the disk table 12 and the chucking member by the positioning protrusion 12a attracting the chucking member.
[0018]
The case body 11 is formed of a damping material, for example, a damping steel plate and a nonmagnetic material, and is positioned in a state of being fixed to the support shaft 10 between the motor rotor 15 and the disk table 12. The case body 11 includes an accommodation portion 18 and a top plate portion 19 that covers the accommodation portion 18, and a central portion is fixed to the support shaft 10 coaxially with the support shaft 10.
[0019]
The accommodating portion 18 includes an annular bottom wall 18a, an outer peripheral wall 18b erected from the outer periphery of the bottom wall 18a, and an inner peripheral wall 18c erected from the inner periphery of the bottom wall 18a. The height of the inner peripheral wall 18c is the same.
[0020]
The top plate portion 19 is formed in a thin annular shape and covers the opening surface of the accommodating portion 18, whereby an annular moving space 11 a is formed in the case body 11.
[0021]
In the moving space 11a, for example, six balance balls 20, 20,. The balance spheres 20, 20,... Are formed in a spherical shape from a magnetic material such as iron or nickel. Surface) 21 is movable in the radial direction up to the position where it abuts on the surface 21 and in the circumferential direction around the support shaft 10. That is, the movement of each balance sphere 20, 20,... Is restricted within an area of a certain distance or less from the rotation axis of the support shaft 10 by the outer inner peripheral surface 21. Further, the balance balls 20, 20,... Are prevented from moving in the axial direction of the support shaft 10 by the bottom wall 18a of the housing portion 18 and the top plate portion 19 of the case body 11, respectively. In addition, the diameter of each balance ball | bowl 20,20, ... is made slightly smaller than the space | interval between the bottom face wall 18a and the lower surface of the top-plate part 19. As shown in FIG.
[0022]
In addition, a magnet (permanent magnet) 22 serving as a magnetic field generating means is disposed at the center in the moving space 11a. The magnet 22 is formed in an annular shape, is provided on the inner peripheral wall 18 c of the housing portion 18 so as to be fitted outside, and is disposed coaxially with respect to the support shaft 10. As shown in FIG. 3, the magnet 22 is two-pole magnetized in a direction perpendicular to the main surface portion, that is, the front surface side and the back surface side are set as magnetic poles. In addition, thin annular yokes 23 and 23 are disposed above and below the magnet 22.
[0023]
Thus, when the support shaft 10 is stopped, the magnet 22 attracts the balance balls 20, 20,... In the moving space 11a regardless of the direction of the support shaft 10 to bring them into contact with the outer peripheral portion. Keep in state. That is, the magnet 22 generates a magnetic force sufficient to pull up the balance balls 20, 20,... That are in contact with the outer inner peripheral surface 21 of the housing portion 18 vertically and attract them to the outer peripheral portion. In particular, the magnetic flux density is increased in the vicinity of the outer peripheral portion of the magnet 22 by the yokes 23, 23 arranged above and below the magnet 22.
[0024]
Each of the balance balls 20, 20,... In the moving space 11 a passes through the balance spheres 20, 20,... With a higher density than in the air. , Are arranged at equal intervals. That is, as shown in FIG. 2, the angles ψ1 to ψ6 about the central axis of the support shaft 10 between the balance balls 20, 20,. As described above, when the balance balls 20, 20,... Are attracted to the outer peripheral portion of the magnet 22, the rotation axis (center axis) of the support shaft 10 to the center of the balance balls 20, 20,. Let r ₁ be the distance (see FIG. 3). This distance r ₁ is equal to the sum of the radius R _{1 of the} magnet 22 and the radius of the balance balls 20, 20,. Then, the balance ball 20, 20 by magnetic force of the this time magnet 22, a suction force to ... and f _1.
[0025]
When a driving current is supplied to the stator coil 17 of the spindle motor 3 and the motor rotor 15 is rotated, the spindle 10, the case body 11, the disk table 12, the chucking member and the recording disk mounted on the disk table 12 together with the motor rotor 15. 1 are rotated together, and the balance balls 20, 20,... Are also rotated around the rotation axis of the support shaft 10 in the moving space 11a. That is, the motor rotor 15, the support shaft 10, the case body 11, the disk table 12, the chucking member, the recording disk 1, and the balance balls 20, 20,... Constitute a composite rotating body (hereinafter, each of these members). ), That is, the center of gravity of the combined rotating body is referred to as “synthetic center of gravity”).
[0026]
When the rotation speed of the recording disk 1 reaches the use rotation range due to the rotation of the spindle motor 3, the balance balls 20, 20,... Are moved in the moving space 11a by centrifugal force as shown in FIGS. It has reached a position where it abuts on the outer peripheral surface 21.
[0027]
In this way, the distance from the rotation axis (center axis) of the support shaft 10 to the center of the balance balls 20, 20,... When the balance balls 20, 20,. Is r _{2 as} shown in FIG. This distance r _2, the balance balls 20, 20 than the radius R ₂ of the moving space 11a, equal to the distance obtained by subtracting a radius of .... Then, the balance ball 20, 20 by magnetic force of the this time magnet 22, a suction force to ... and f _2. The suction force f ₂ is balanced spheres 20, 20, a force smaller than the centrifugal force acting on ....
[0028]
When the recording disk 1 to be rotated has no weight imbalance (eccentric gravity center) or when the recording disk 1 is not mounted on the disk table 12, each balance ball 20, 20,. As shown in FIG. 4, they are positioned so as to be equiangularly spaced around the rotation axis of the support shaft 10.
[0029]
The recording disk 1 may have a weight imbalance during manufacture. Here, unbalance means that the center of gravity of the recording disk 1 is not located at the center of the recording disk 1. For example, unbalance means that the substrate thickness of the recording disk 1 is not uniform or the density is not uniform. It happens when
[0030]
If the recording disk 1 having such an imbalance is rotated together with the disk table 12, the spindle motor 3 and the like rotating the recording disk 1 vibrate including the mechanical chassis 5. When the recording disk 1 having such a weight imbalance is mounted on the disk table 12 and rotated, the balance balls 20, 20,... In accordance with the unbalance direction and the unbalance amount D, the movement is made in the movement space 11a to a position where the unbalance is canceled. That is, each of the balance balls 20, 20,... Rotates separately from the case body 11 even when the case body 11 is rotated. It rotates with the case body 11. .. Gradually move to a position facing the unbalance direction of the recording disk 1.
[0031]
As shown in FIG. 6, the position of each balance ball 20, 20,... In a state where each balance ball 20, 20,. Are arranged at equal intervals from the position of the angle + θ _{n to} the position of the angle −θ _n through the opposite side of the unbalance direction. (That is, there is no balance sphere 20, 20,... In the range of the angle ± θ _{n with} respect to the unbalance direction). Here, when the mass of the balance spheres 20, 20,... Is m, the angle θ _n is an angle that satisfies the following formula.
[0032]
[Expression 1]

[0033]
[Expression 2]

[0034]
At this time, the center of gravity of each of the balance balls 20, 20,... Is a position facing the unbalance direction via the rotation center, and is located on the facing line.
[0035]
In this state, the entire center of gravity of the case body 11 and the balance balls 20, 20,... Deviated from the rotation center due to the unbalance of the recording disk 1 is located on the rotation axis of the combined rotation body.
[0036]
As described above, when the recording disk 1 having an unbalance is rotated, the balance balls 20, 20,... Are appropriately moved by the so-called self-aligning action, whereby the position of the combined center of gravity is rotated. Located on the axis. Therefore, the combined rotating body rotates without vibration, and therefore the recording disk 1 having unbalance can be rotated with its center of gravity positioned on the rotation axis.
[0037]
Such self-aligning action is achieved when the rotational frequency of the composite rotator is within the resonance frequency of the dampers 6, 6,... (Planes perpendicular to the rotational axis of the composite rotator (x and y planes in FIG. 1)). The resonance frequency is effectively generated when the resonance frequency becomes higher than or equal to the direction. That is, a recording disk that records or reproduces information signals at a high speed can be generated effectively.
[0038]
In the rotation drive mechanism 9 described above, since the balance balls 20, 20,... Are arranged at equiangular intervals when the case body 11 is stopped, at the start of rotation of the case body 11, Each balance ball 20, 20,... Does not cause unbalance.
[0039]
Therefore, as described above, even if the recording disk 1 having a heavy unbalance is rotated by the rotary drive mechanism 9 including the balance balls 20, 20,. . That is, in the disk drive device 2, information signals can be written or read satisfactorily with respect to the signal recording surface of the recording disk 1 having a heavy imbalance.
[0040]
When the recording disk 1 is thus rotated, the optical pickup device 4 irradiates the recording disk 1 with a laser beam and receives and detects the reflected light. The optical pickup device 4 is moved along the guide shafts 7 and 7 so as to move away from the support shaft 10, that is, in the radial direction of the recording disk 1 mounted on the disk table 12. It is moved over the inner and outer circumferences. Then, the information signal is written to or read from the recording disk 1 by the optical pickup device 4.
[0041]
By the way, in the rotation drive mechanism 9, when the spindle motor 3 is started, that is, when the case body 11 starts to rotate from the stopped state, the balance balls 20, 20,. The effect of the self-aligning action can be obtained more quickly when they are activated synchronously without relative movement. That is, as shown in FIG. 7, the difference between the rotational speed of the case body 11 and the rotational speeds of the balance balls 20, 20,. ,..., A resonance frequency equal to or higher than 0 is desirable.
[0042]
Here, when the case body 11 is activated, the balance balls 20, 20,... Are synchronously activated without being moved relative to the case body 11 as follows. That is, the rotational torque transmitted from the case body 11 to the balance spheres 20, 20,... Is the transmission torque T ₀ , the moment of inertia of the balance spheres 20, 20,. The rotational torque of 20,... Is β, and the starting torque T ₁ = J · β is set. Then, the balance balls 20, 20, the mass of ... a m, balancing balls 20 and 20 from the rotation axis, the distance to ... as R, put and T ₂ = m · R. Then, when the case body 11 starts rotating from the stopped state, as shown in FIG.
T ₁ + T ₂ <T ₀
Is established, the balance balls 20, 20,... Are activated in synchronism with the activation of the case body 11 regardless of the direction (inclination) of the support shaft 10 (note that the support shaft 10 If only considering the case where the axial direction is vertical, it is sufficient that T ₁ <T ₀ holds.)
[0043]
When the rotation frequency of the case body 11 becomes equal to or higher than the resonance frequency of the dampers 6, 6,... (Resonance frequency in a direction perpendicular to the rotation axis of the case body 11), the balance balls 20, 20. When the torque acting on the balance balls 20, 20,... Is adjusted torque T ₃ as torque for moving the case body 11 in the circumferential direction around the rotation axis of the case body 11, FIG. As shown in
T ₀ <T ₃
Must be established. If this condition is not satisfied, automatic alignment is not performed. Here, when the case body 11 balance balls 20, 20, the transmission torque T ₀ the rotational torque transmitted against ... is constant regardless of the rotational speed of the case body 11,
T ₁ + T ₂ <T ₀ <T ₃
Must be established. Therefore, if the transmission torque T ₀ is large in the low rotation speed region and small in the high rotation speed region (the use rotation region ω, ω ₁ ≦ ω ≦ ω ₂ ), the above condition can be easily satisfied. .
[0044]
In the rotation drive mechanism 9 described above, each balance ball 20, 20,... Is attracted to the magnet 22 side when the case body 11 starts rotating from a stopped state. Because of this, the case body 11 follows the case body 11 by the starting torque transmitted from the case body 11 to the balance balls 20, 20,. That is, the balance balls 20, 20,... Are attracted to the outer peripheral portion of the magnet 22 when the case body 11 is stopped, and the balance balls 20, 20,. When the rolling friction coefficient between the outer peripheral portion is μ ₁ , the transmission torque T ₀ transmitted from the case body 11 to the balance balls 20, 20,.
T ₀ = μ ₁ · f ₁ · r ₁
It becomes. The starting torque T ₁ when the angular acceleration at the time of starting is β is
T ₁ = m · r ₁ ² · β
It becomes. Since it is necessary that T ₁ <T ₀ ,
m · r ₁ ² · β <μ ₁ · f ₁ · r ₁
m ・ r ₁・ β <μ ₁・ f ₁
It becomes. Moreover, the balance balls 20, 20, also the magnetic resistance due to the magnetic flux generated by the magnet 22 during ... are passed, the effect of increasing the transmission torque T _0.
[0045]
When the support shaft 10 is horizontal, the balance balls 20, 20,... Are magnets in the weight of the balance balls 20, 20,..., And in the use rotation range ω (ω ₁ ≦ ω ≦ ω ₂ ). Considering that it must be separated by centrifugal force from 22
m · g <f ₁ <m · r ₁ · ω ₁ ² -m · g (where g is the acceleration of gravity)
Must be established. Due to this condition, the balance balls 20, 20,... Are separated from the outer peripheral portion of the magnet 22 by centrifugal force when the case body 11 is rotated at a high speed. At this time, the transmission torque T ₀ is decreased, and the conditions for performing the automatic alignment are easily satisfied. That is, the balance balls 20, 20, when the rolling friction coefficient between the outer the peripheral surface 21 of ... the movement space 11a and mu _2, the balance balls 20, 20, ... are outside the periphery 21 The transmission torque T ₀ when abutting is
T ₀ = μ ₂ · r ₂ (m · r ₂ · ω ₂ ² −f ₂ + m · g)
The transmission torque T ₀ only needs to be smaller than the adjustment torque T ₃ . In addition, when the rotation speed of the case body 11 becomes lower than the use rotation area, each balance ball 20, 20,... Is again attracted to the outer peripheral portion of the magnet 22.
m · g <f ₂ <m · r ₂ · ω ₁ ² −m · g
Needs to be satisfied.
[0046]
As shown in FIG. 7, the aligning action is performed when the balance balls 20, 20,... Are rotated in synchronization with the case body 11, and the case body 11 starts to rotate from the stopped state. In doing so, the effect of the self-aligning action can be obtained more quickly when the balance balls 20, 20,... Are activated synchronously without moving relative to the case body 11. Therefore, it is desirable that the balance spheres 20, 20,... Are attracted to the magnet 22 for as long as possible against the centrifugal force until the rotational speed of use is reached. Need to be larger.
[0047]
As a means for increasing the magnetic force of the magnet 22, it is conceivable to increase the size of the magnet 22. However, if the size of the magnet 22 is increased, the rotational drive mechanism is increased in size and the disk drive device is increased in size accordingly. End up.
[0048]
Therefore, in the rotation drive mechanism 9 described above, since the yokes 23 and 23 are arranged above and below the magnet 22 to increase the attractive force by the magnet 22, the balance ball 20 is rotated when the case body 11 is rotated. , 20,... Are attracted for a long time, and when the balance spheres 20, 20,... Are separated from the magnet 22 by centrifugal force, the rotation is performed in synchronization with the rotation of the case body 11. Probability is high.
[0049]
Accordingly, the magnet 22 can be made thinner accordingly, and thereby the disk drive device 2 can be made thinner.
[0050]
In addition, in order to quickly execute the aligning action after the balance balls 20, 20,... Are separated from the magnet 22 by centrifugal force, the case bodies of the balance balls 20, 20,. It is necessary that the relative rotation with respect to 11 be performed without resistance. That is, it is desirable that the frictional force generated between the balance balls 20, 20,... And the case body 11 with the rotation of the balance balls 20, 20,.
[0051]
Therefore, in the rotational drive mechanism 9 described above, the balance balls 20, 20,... That are spherical bodies are used as the balance members, and the balance balls 20, 20,. The frictional force generated in the is reduced.
[0052]
Therefore, after the balance balls 20, 20,... Are separated from the magnet 22, the relative rotation of the balance balls 20, 20,. Performed quickly.
[0053]
In the above description, the magnet 22 is provided in the central portion of the moving space 11a. However, the magnet 22A may be provided in the outer peripheral portion of the moving space 11a (see FIGS. 9 and 10).
[0054]
In this way, when the magnet 22A is provided on the outer peripheral portion of the moving space 11a, the balance balls 20, 20,... Are always independent of the rotational speed of the case body 11 and the inner peripheral surface 22a of the magnet 22A. However, when the balance balls 20, 20,... Are moved along the inner peripheral surface 22a of the magnet 22A, a self-aligning action is generated (see FIG. 10).
[0055]
Moreover, although what showed each balance member arrange | positioning to the case body 11 was shown above, you may form the movement space 11a in which each balance member is arrange | positioned in the disk table 12A, as shown in FIG. . In this case, the disk table 12A functions as a case body.
[0056]
If the moving space 11a is formed in the disk table 12A in this way, there is no need to provide the case body 11 as a separate member for arranging the balance members, the number of parts of the rotary drive mechanism is reduced, and the cost is reduced. Contribute to.
[0057]
Further, as shown in FIG. 12, the moving space 11 a may be formed in the chucking member 24 instead of the disk table. In this case, the chucking member 24 functions as a case body.
[0058]
If the moving space 11a is formed in the chucking member 24 as described above, the case body 11 as a separate member for arranging the balance members is provided in the same manner as when the moving space 11a is formed in the disc table 12A. This is unnecessary, and the number of parts of the rotary drive mechanism is reduced, contributing to cost reduction.
[0059]
In the above-described embodiment, the example in which the self-aligning action is performed on the synthetic rotating body when the unbalanced recording disk 1 is mounted on the disk table has been described. Even when the members other than the recording disk 1 are unbalanced, the rotational driving mechanism 9 can execute the self-aligning action to suppress vibration during rotation.
[0060]
In the above-described embodiment, the present invention is applied to a disk drive device that performs reproduction or recording on a recording disk such as an optical disk or a magneto-optical disk . However, the present invention is not limited to industrial machines and other devices. It can also be applied to electrical appliances .
[0061]
【The invention's effect】
As is apparent from the above description, in the disk drive equipped with the rotation drive mechanism and the rotation drive mechanism of the present invention, a case body that is rotated by a rotation drive means via a support shaft, and formed in the case body A moving space in which the cross-sectional shape in the direction orthogonal to the axial direction forms an annular shape, a balance member made of a magnetic material and in contact with the case body and arranged to be movable in the moving space, and a center in the moving space And a yoke disposed in the moving space, and the balance member is attracted to the outer periphery of the magnet when the case body is not rotating, and the case body is rotated. sometimes the balance member by centrifugal force is spaced from the outer peripheral portion of the magnet, the balance member is rotated with the rotation of the case body is rotated by the rotary drive means Since combined center of gravity of the timber has to be positioned on the rotation axis, or a case body which is rotated via a support shaft by the rotational driving means, the direction of the cross-sectional shape perpendicular to the axial direction is formed in the case body An annular moving space, a balance member made of a magnetic material and in contact with the case body and arranged to be movable in the moving space, and a magnet that is arranged on the outer periphery of the moving space and attracts the balance member And a yoke disposed in the moving space, the balance member is attracted to the inner periphery of the magnet when the case body is not rotated, and the balance member is attracted to the inner periphery of the magnet when the case body is rotated. Since the balance member is rotated in accordance with the rotation of the case body, the combined center of gravity of the member rotated by the rotation driving means is positioned on the rotation axis. With synthetic rotator is made in a state where the rotary can be rotated without causing vibration does not cause the eccentricity of the rotation center, the suction force is increased by the magnet because the yoke is provided in the mobile space, Accordingly, the magnet can be made thinner, which contributes to downsizing of the rotary drive mechanism.
[0062]
In the invention described in claim 2, the magnet is positioned at the center of the moving space, the balance member is formed as a spherical body, and the spherical body is adsorbed on the outer periphery of the magnet when the case body is not rotating. Since the spherical body is separated from the outer periphery of the magnet by centrifugal force when the case body rotates, the starting torque is transmitted from the case body when the case body starts rotating from the stopped state, and the balance member is The body follows the body and starts rotating together with the case body, and the self-aligning action is quickly executed.
[0063]
In the invention described in claim 3, the magnet is positioned at the outer peripheral portion of the moving space, the balance member is formed as a spherical body, and the spherical body is stopped at the inner peripheral portion of the magnet when the case body is not rotated. Since the spherical body is moved in the circumferential direction while being attracted to the inner periphery of the magnet when the case body is rotated, the case body starts rotating from the stopped state. The starting torque is transmitted from the case body, the balance member follows the case body and starts rotating together with the case body, and the self-aligning action is quickly executed.
[0064]
It should be noted that the specific shapes and structures of the respective parts shown in the above-described embodiments are merely examples of implementation in carrying out the present invention, and as a result, the technical scope of the present invention. Should not be interpreted in a limited way.
[Brief description of the drawings]
FIG. 1 shows an embodiment of a rotary drive mechanism and a disk device provided with a rotary drive mechanism according to the present invention together with FIGS. 2 to 8, and this figure is a schematic perspective view showing a disk drive device provided with the rotary drive mechanism. It is.
FIG. 2 is an enlarged horizontal sectional view showing a case body.
FIG. 3 is an enlarged longitudinal sectional view showing a synthetic rotating body.
FIG. 4 is an enlarged horizontal sectional view showing a state where a case body is rotated.
FIG. 5 is an enlarged longitudinal sectional view showing a state where a case body is rotated.
FIG. 6 is an enlarged horizontal sectional view of the case body showing a state in which the self-aligning action is executed.
FIG. 7 is a graph showing changes in rotation speeds of a case body and a balance member in a rotation drive mechanism.
FIG. 8 is a graph showing changes in rotational torque transmitted from the case body to the balance member in the rotational drive mechanism.
FIG. 9 shows another embodiment of the rotational drive mechanism together with FIG. 10, and this figure is an enlarged horizontal sectional view of the case body showing a state before the self-aligning action is executed.
FIG. 10 is an enlarged horizontal sectional view of the case body showing a state in which the self-aligning action is performed.
FIG. 11 is an enlarged longitudinal sectional view showing another form of the case body.
FIG. 12 is an enlarged longitudinal sectional view showing still another form of the case body.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Disk drive apparatus (disk apparatus), 3 ... Spindle motor (rotation drive means), 9 ... Rotation drive mechanism, 10 ... Support shaft, 11 ... Case body, 11a ... Moving space, 20 ... Balance ball (balance member), 22 ... magnet, 23 ... yoke, 12A ... disc table (case body), 22A ... magnet, 24 ... chucking member (case body)

Claims (5)

A case body rotated via a support shaft by a rotation driving means;
A moving space in which the cross-sectional shape in the direction perpendicular to the axial direction formed in the case body forms an annular shape,
A balance member formed of a magnetic material and in contact with the case body and arranged to be movable in the moving space;
A magnet disposed at the center of the moving space and attracting the balance member;
A yoke disposed in the moving space,
The balance member is adsorbed on the outer periphery of the magnet when the case body is not rotating, and the balance member is separated from the outer periphery of the magnet by centrifugal force when the case body is rotating,
A rotation drive mechanism , wherein the balance member is rotated along with the rotation of the case body, and the combined center of gravity of the member rotated by the rotation drive means is positioned on the rotation axis. A case body rotated via a support shaft by a rotation driving means;
A moving space in which the cross-sectional shape in the direction perpendicular to the axial direction formed in the case body forms an annular shape,
A balance member formed of a magnetic material and in contact with the case body and arranged to be movable in the moving space;
A magnet disposed on the outer periphery of the moving space and attracting the balance member;
A yoke disposed in the moving space,
When the case body is not rotated, the balance member is attracted to the inner peripheral portion of the magnet, and when the case body is rotated, the balance member is moved in the circumferential direction while being attracted to the inner peripheral portion of the magnet. ,
The balance member is rotated along with the rotation of the case body, and the combined center of gravity of the member rotated by the rotation driving means is positioned on the rotation axis.
A rotational drive mechanism characterized by that. The balance member rotary drive mechanism according to claim 1 or claim 2, characterized in that it is formed as a spherical body. The yoke rotary drive mechanism according to claim 1 or claim 2, characterized in that disposed above and below the magnet. A case body rotated via a support shaft by a rotation driving means;
A moving space in which the cross-sectional shape in the direction perpendicular to the axial direction formed in the case body forms an annular shape,
A balance member formed of a magnetic material and in contact with the case body and arranged to be movable in the moving space;
A magnet disposed in the moving space and attracting the balance member;
A yoke disposed in the moving space,
A disk device comprising a rotation drive mechanism in which the balance member is rotated with the rotation of the case body, and the combined center of gravity of the member rotated by the rotation drive means is positioned on the rotation axis.

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