JP3872859B2

JP3872859B2 - Depressurized optical deflector

Info

Publication number: JP3872859B2
Application number: JP4685397A
Authority: JP
Inventors: 明義高橋; 仲蔵有山; 裕樹松下
Original assignee: Nidec Copal Electronics Corp
Current assignee: Nidec Copal Electronics Corp
Priority date: 1997-01-24
Filing date: 1997-01-24
Publication date: 2007-01-24
Anticipated expiration: 2017-01-24
Also published as: JPH10206780A

Description

【０００１】
【発明の属する技術分野】
本発明は、動圧軸受を介して高速回転する回転鏡により一定角度範囲にレーザ光等を偏向反射させる光偏向器に関し、特に、減圧手段による軽負荷高速回転を確保しつつ、構成のコンパクト化を可能とする減圧式光偏向器に関する。
【０００２】
【従来の技術】
図５は従来の減圧式光偏向器の縦断面図である。この光偏向器１０１は、ケース１０２内に固定した動圧軸１０３に動圧スリーブ１０４を介して多面鏡または単面鏡による回転鏡１０５（以下、単に「回転鏡」という。）を備える。上記動圧スリーブ１０４は、動圧軸１０３に形成したヘリングボーン溝１０６，１０６によるラジアル動圧軸受によって回転可能に支持される。また、動圧スリーブ１０４とケース２との間にスラスト方向を支持する磁気軸受１０７ａ、回転駆動部１０７ｂを介設する。このような構成をなす光偏向器１０１は、その回転鏡１０５を高速回転することにより、一定角度範囲にレーザ光等を偏向反射する。
【０００３】
上記動圧軸１０３は、ラジアル動圧軸受１０６，１０６の他に、その側方に軸方向の空気送り作用をなすスパイラル溝１０８，１０８とその送り先側に開口する外気連通孔１０９，１０９とからなる排気機構を備える。この排気機構はラジアル動圧軸受１０６，１０６の両側方に対称的に構成し、動圧スリーブの両端１０４ａ，１０４ａからケース内の空気を同時に排気することによって減圧作用を生じ、軸受剛性を確保しつつケース内を低圧化することにより回転鏡１０４その他の回転抵抗を抑えて軽負荷高速回転を可能とする。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記光偏向器１０１は、略３００００ｒｐｍに及ぶ高速回転の回転部材を支承するために動圧軸受１０６，１０６を使用し、この動圧軸受は動圧軸１０３と動圧スリーブ１０４との間の略１〜５μｍの軸線方向に連続する空隙を有することから、この空隙を挟んで動圧軸受１０６，１０６の両端部に上記排気機構を対称的に構成せざるを得ないので、光偏向器の軸方向の構成寸法の増大を招いている。
【０００５】
本発明の目的は、減圧手段による軽負荷高速回転を確保しつつ、構成のコンパクト化を可能とする減圧式光偏向器を提供することにある。
【０００６】
【課題を解決するための手段】
上記課題を解決するためにヘリングボーン溝その他の動圧発生部による動圧軸受を介して互いに回転可能に嵌合する動圧軸および動圧スリーブからなるラジアル支持部を備え、このラジアル支持部を介してケース内に回転鏡その他の回転部材を回転可能に支持する光偏向器において、
前記ケースを密閉形成するとともに、前記動圧スリーブは一端を閉じて回転部材側に取り付け、前記動圧軸は片持ちにケース側に取り付け、かつ、前記動圧軸には、動圧軸の自由端方向に送気するスパイラル溝と、動圧軸の外周面に開口する半径部とこの半径部と連通して動圧軸の中心に沿ってその外側端に開口する中空部とからなり外気と連通する外気連通孔を形成し、
前記動圧軸の自由端と動圧スリーブとの間に、動圧スリーブのスラスト変位に応じて容積が変わる軸端室を形成し、この軸端室と外気と動圧軸内部に、上記中空部と連通し、かつ上記半径部の上方に減衰部材を介設した、前記スラスト変位の急激な変化を抑える流路抵抗を有する減衰通路を形成したことを特徴とするものである。
又、上記流路抵抗を、焼結メタルからなる減衰部材によって構成したことを特徴とするものである。
【０００７】
上記構成の減圧式光偏向器は、動圧軸および動圧スリーブの間の隙間は動圧軸の固定端側においてのみケース内と連通する。そして、動圧軸の自由端方向に送気するスパイラル溝と、その送り先側に開口して外気と連通する外気連通孔とを上記動圧軸受の側方のラジアル支持部に形成したことから、ケース内の空気はスパイラル溝と外気連通孔とを介して排出され、ケース内が減圧される。
また、上記流路抵抗を、焼結メタルからなる減衰部材によって構成した場合は、機械加工の困難な直径０．１ｍｍ以下の円孔に相当する流量比例抵抗を、回転部材側の質量に応じ、また、軸端室の容積に応じて精度良く設定することができる。
【０００８】
【発明の実施の形態】
図１は本発明の実施の形態を示す動圧軸固定の減圧式光偏向器の縦断面図である。減圧式光偏向器１は、ケース２内に動圧によるラジアル支持部３を介して回転鏡４その他の回転部材を回転可能に支持して構成する。
【０００９】
ケース２の中央部にラジアル支持部３の動圧軸５を片持ちに起立固定する。ラジアル支持部３は、図示の動圧軸５に動圧発生部６を形成し、または、動圧スリーブ７に動圧発生部６を形成して動圧軸５と動圧スリーブ７とを互いに回転可能に嵌合する。この動圧スリーブ７に回転鏡４その他の回転部材を取付け、蓋部材８を取付けてケース２内を密閉する。上記動圧発生部６は図示の一体形成または分離形成のヘリングボーン溝６、その他各種の動圧支持手段による動圧軸受をなす。
【００１０】
動圧スリーブ７はその一端７ａを閉じた袋状に形成し、ケース２に片持ち固定した動圧軸５と嵌合する。この動圧軸５の自由端５ａ方向に送気するスパイラル溝９を動圧発生部６の側方のラジアル支持部３に形成し、その送り先側に外気連通孔１０を開口する。スパイラル溝９は図示の動圧軸５または動圧スリーブ７に、外気連通孔１０は図示の動圧軸５に、またはこの動圧軸５を介して動圧スリーブ７に形成する。スパイラル溝９はケース２内の空気を自由端５ａ方向に片送りし、外気連通孔１０から排出されることからスパイラル溝９と外気連通孔１０は排気機構をなす。
【００１１】
動圧スリーブ７はその外周のケース２との間にスラスト磁気軸受１１、回転駆動部１２を備える。この回転駆動部１２は、マグネット１３を回転側とし、コイル１４、ヨーク１５、および、回転センサ１２ａ等を固定側として構成する。
【００１２】
このような構成をなす減圧式光偏向器１は、回転部材４側をなす動圧スリーブ７の一端を閉じ、この動圧スリーブ７をケース２側の動圧軸５と嵌合したことから、動圧スリーブ７の開放端７ｂ側が動圧軸５の固定端５ｂ側に嵌合し、したがって動圧軸５および動圧スリーブ７の間の隙間は動圧スリーブの開放端７ｂにおいてのみケース２内と連通する。
【００１３】
このケース２に固定した動圧軸５の自由端５ａ方向に送気するスパイラル溝９とその送り先側に開口する外気連通孔１０とからなる排気機構を形成したことから、ケース２内の空気は、対称配置の排気機構を要することなく、単一の排気機構によるスパイラル溝９と外気連通孔１０とを介して排出され、ケース２内が減圧される。
【００１４】
したがって、本発明の減圧式光偏向器は、動圧軸上に排気機構を対称配置に要することなく、スパイラル溝と外気連通孔とによる単一の排気機構により、軽負荷高速回転を確保しつつ、構成のコンパクト化を可能とする。また、動圧軸５の動圧発生部６より固定端５ｂ側に外気連通孔１０を開口すれば、外気が軸受背圧として作用するので、排気による軸受部の低圧化を回避して軸受剛性を確保することができる。
【００１５】
上記外気連通孔１０は動圧軸５の外周面に開口する半径部１０ａとこの半径部１０ａと連通して動圧軸５の中心に沿ってその外側端に開口する中空部１０ｂとからなり、この中空部１０ｂは、さらに、他の自由端５ａまで貫通し、同自由端５ａ側に動圧スリーブ７によって形成される軸端室１６と連通する。
【００１６】
この軸端室１６に至る中空部１７により、ヘリングボーン溝等の動圧軸受６によって軸線方向の気体流動を伴う場合、および、上記排気機構による気体流動を受ける場合でも軸端室１６の圧力変動が回避されるので、軸線方向力の発生を抑えることができる。上記排気機構によってケース２内が減圧された際は、両中空部１０ｂ，１７を介して軸端室１６に作用する外気圧が、動圧軸５と動圧スリーブ７との間のスラスト変位に対応して作用するスラスト磁気軸受１１のスラスト力とバランスする。
【００１７】
この軸端室１６に至る両中空部１０ｂ，１７のいずれか（図示例は中空部１７）に空気流通を抑制する焼結メタル等による減衰部材１８を介設して減衰通路を形成し、必要に応じて図示せぬフィルタを中空部１０ｂの開口に取付ける。
【００１８】
上記軸端室１６は動圧軸５に対する動圧スリーブ７のスラスト変位に応じた可変容積をなし、このスラスト変位動作に応じて減衰部材１８を介する空気流動が生じることから、この減衰部材１８をスラスト変位の急激な変化を抑えるに足る流路抵抗に設定することにより、衝撃等による高速のスラスト変位動作が抑えられるとともに、排気機構や動圧軸受による緩慢な空気流動に対して一定圧力の外気と連通して軸端室１６の内圧が一定の外気圧に保たれるので回転の安定を図ることができる。また、焼結メタルによって減衰部材を形成することにより、機械加工の困難な直径０．１ｍｍ以下の円孔に相当する流量比例抵抗を、回転部材側の質量に応じ、また、軸端室の容積に応じて精度良く設定することができる。
【００１９】
図２は図１の減圧式光偏向器のラジアル軸受の構成例である。本発明の減圧式光偏向器は、溝２１，２２を分離形成した分離ヘリングボーン溝による動圧軸（Ａ）、負荷に応じて複数の軸受２３，２４を備えた動圧軸（Ｂ）等、ヘリングボーン溝の密接又は分離、軸受の数に関わらず、各種の動圧軸受の適用が可能である。特に、軸線方向の気体流動を伴わない周回流動による多偏弧断面形状の動圧軸２５と動圧スリーブ２６とによる動圧軸受（Ｃ）等の場合は、スパイラル溝９の排気作用と分離して減衰部材１８の容量設定が可能となる。
【００２０】
図３は他のラジアル動圧軸受の図２と同様の図である。水抜き溝３１を形成した動圧スリーブ３２と多偏弧断面形状の動圧軸３３とによる高機能の周回流動型動圧軸受（Ａ）の適用が可能である。その他、方向性を有する多偏弧断面形状の動圧スリーブ３４と動圧軸３５とによる動圧軸受（Ｂ）、方向性を有する多角辺断面形状の動圧軸３６と動圧スリーブ３７とによる動圧軸受（Ｃ）等、周回流動による各種の動圧軸受の適用が可能である。
【００２１】
図４は動圧軸回転の減圧式光偏向器の図１と同様の図である。前記同様の部材はその符号を付して説明を省略する。
減圧式光偏向器４１は、密閉したケース２内に動圧によるラジアル支持部４２を介して回転鏡４等の回転部材を回転可能に収容して構成する。
【００２２】
ラジアル支持部４２は、ケース２の中央部に起立形成した動圧スリーブ４３と、回転部材側をなす動圧軸４４とを互いに回転可能に嵌合する。図示の動圧軸４４に動圧発生部６を形成し、または、動圧スリーブ４３に動圧発生部６を形成して動圧軸受を形成する。動圧軸４４は取付け部材４５に対して片持ちに一体固定し、この取付け部材４５を介して回転鏡４その他の回転部材を取付け、蓋部材８を取付けてケース２を気密に構成する。
【００２３】
動圧軸４４の自由端４４ａ方向に送気するスパイラル溝９を動圧発生部６の側方のラジアル支持部４２に形成し、その送り先側に外気連通孔１０を開口する。スパイラル溝９は図示の動圧軸４４または動圧スリーブ４３に、外気連通孔１０は図示の動圧軸４４に、またはこの動圧軸４４を介して動圧スリーブ４３に形成し、これらスパイラル溝９と外気連通孔１０とにより排気機構を構成する。
【００２４】
取付け部材４５はその外周のケース２との間にスラスト磁気軸受１１、回転駆動部１２を備える。この回転駆動部１２は、マグネット１３を回転側とし、コイル１４、ヨーク１５、および、回転センサ１２ａ等を固定側として構成する。
【００２５】
このような構成をなす減圧式光偏向器４１は、回転部材４側に動圧軸４４を片持ちに取付け、ケース２側の動圧スリーブ４３と嵌合したことから、動圧スリーブ４３の開放端４３ａ側が動圧軸４４の固定端４４ｂ側に嵌合したことから、動圧軸４４および動圧スリーブ４３の間の隙間はその開放端４３ａにおいてのみケース２内と連通する。
【００２６】
上記動圧軸４４の自由端４４ａ方向に送気するスパイラル溝９とその送り先側に開口する外気連通孔１０とからなる排気機構を動圧軸受の側方に形成したことから、ケース２内の空気はスパイラル溝９と外気連通孔１０とを介して排出され、ケース内が減圧される。
【００２７】
したがって、本発明の減圧式光偏向器は、動圧軸上に排気機構を対称配置に要することなく、スパイラル溝と外気連通孔とによる単一の排気機構により、軽負荷高速回転を確保しつつ、構成のコンパクト化を可能とする。また、動圧軸４４の動圧発生部６より固定端４４ｂ側に外気連通孔１０を開口すれば、外気が軸受背圧として作用するので軸受剛性を確保することができる。
【００２８】
上記排気機構によってケース２内が減圧された際は、動圧軸４４に作用する外気圧が、動圧軸４４と動圧スリーブ４５との間のスラスト変位と対応して作用するスラスト磁気軸受１１のスラスト力とバランスする。
【００２９】
上記動圧軸４４の自由端４４ａ側に、その外方を閉じて軸端室４６を形成する。この軸端室４６を外気側と連通し、かつ、その空気流通を抑制するための減衰部材４７を介設し、必要に応じて図示せぬフィルタで覆う。これにより、前記同様に減衰部材４７の流路抵抗によって上記スラスト変位動作を抑えることができ、かつ、一定圧力の外気と連通して軸端室４６の内圧を一定に保つことができる。
【００３０】
【発明の効果】
本発明による減圧式光偏向器は以下の効果を奏する。ラジアル支持部の一側をなす動圧スリーブは一端を閉じて回転部材側に、他側をなす動圧軸は片持ちにケース側に形成し、互いに嵌合したことから、動圧スリーブの開放端側が動圧軸の固定端側に嵌合する。これにより、動圧軸および動圧スリーブの間の隙間は動圧軸の固定端側においてのみケース内と連通する。そして、動圧軸の自由端方向に送気するスパイラル溝と、その送り先側に開口して外気と連通する外気連通孔とを上記動圧軸受の側方のラジアル支持部に形成したことから、ケース内の空気はスバイラル溝と外気連通孔とを介して排出され、ケース内が減圧される。
【００３１】
したがって、本発明の減圧式光偏向器は、動圧軸上に排気機構を対称配置に要することなく、スパイラル溝と外気連通孔とによる単一の排気機構により、軽不可高速回転を確保しつつ、構成のコンパクト化を可能とする。
又、前記外気連通孔が動圧軸受より動圧軸の固定端側に開口したため、外気連通孔を介して外気が軸受背圧として作用するので軸受剛性を確保することができる。
又、前記動圧軸の自由端に臨んでこの動圧軸と動圧スリーブとの間のスラスト変位に応じた容積をなす軸端室を形成し、この軸端室と外気との間に上記スラスト変位の急激な変化を抑える流路抵抗を有する減衰通路を形成したため、動圧軸と動圧スリーブとの間のスラスト変位動作による減衰通路の空気流に作用する流路抵抗によって衝撃等による高速のスラスト変位動作が抑えられ、また、減衰通路は一定圧力の外気と連通することから、排気機構は一定の背圧によって排気機能が確保され、かつ、軸端室の内圧が外気圧に保たれて回転の安定を図ることができる。
又、上記流路抵抗を、焼結メタルからなる減衰部材によって構成した場合は、機械加工の困難な直径０．１ｍｍ以下の円孔に相当する流量比例抵抗を、回転部材側の質量に応じ、また、軸端室の容積に応じて精度良く設定することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態を示す動圧軸固定の減圧式光偏向器の縦断面図
【図２】図１の減圧式光偏向器のラジアル軸受の構成例
【図３】他のラジアル動圧軸受の図２と同様の図
【図４】動圧軸回転の減圧式光偏向器の図１と同様の図
【図５】従来の減圧式光偏向器の縦断面図
【符号の説明】
１減圧式光偏向器
２ケース
３ラジアル支持部
４回転鏡（回転部材）
５動圧軸
５ａ自由端
５ｂ固定端
６ヘリングボーン溝（動圧発生部）
７動圧スリーブ
７ａ一端
７ｂ開放端
８蓋部材
９スパイラル溝（排気機構）
１０外気連通孔（排気機構）
１０ａ半径部
１０ｂ中空部
１６軸端室
１７中空部
１８減衰部材（減衰通路）
４１減圧式光偏向器
４２ラジアル支持部
４３動圧スリーブ
４３ａ開放端
４４動圧軸
４４ａ自由端
４４ｂ固定端
４５取付け部材
４６軸端室
４７減衰部材（減衰通路）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical deflector that deflects and reflects a laser beam or the like within a certain angle range by a rotating mirror that rotates at high speed via a hydrodynamic bearing, and in particular, a compact structure while ensuring light load high speed rotation by a decompression means. The present invention relates to a pressure-reducing optical deflector that enables the above.
[0002]
[Prior art]
FIG. 5 is a longitudinal sectional view of a conventional pressure-reducing optical deflector. The optical deflector 101 includes a rotating mirror 105 (hereinafter simply referred to as “rotating mirror”) using a polygonal mirror or a single-sided mirror via a dynamic pressure sleeve 104 on a dynamic pressure shaft 103 fixed in a case 102. The dynamic pressure sleeve 104 is rotatably supported by a radial dynamic pressure bearing formed by herringbone grooves 106 and 106 formed in the dynamic pressure shaft 103. In addition, a magnetic bearing 107 a and a rotation drive unit 107 b that support the thrust direction are interposed between the dynamic pressure sleeve 104 and the case 2. The optical deflector 101 having such a configuration deflects and reflects a laser beam or the like within a certain angle range by rotating the rotary mirror 105 at a high speed.
[0003]
The dynamic pressure shaft 103 includes, in addition to the radial dynamic pressure bearings 106 and 106, spiral grooves 108 and 108 that form an air feeding action in the axial direction on the sides thereof, and external air communication holes 109 and 109 that open on the destination side. An exhaust mechanism is provided. This exhaust mechanism is configured symmetrically on both sides of the radial dynamic pressure bearings 106 and 106, and the air in the case is exhausted from both ends 104a and 104a of the dynamic pressure sleeve at the same time, thereby generating a pressure reducing action and ensuring the rigidity of the bearing. However, by reducing the pressure in the case, the rotating mirror 104 and other rotational resistances can be suppressed to enable light load and high speed rotation.
[0004]
[Problems to be solved by the invention]
However, the optical deflector 101 uses dynamic pressure bearings 106 and 106 to support a rotating member rotating at a high speed of approximately 30000 rpm, and the dynamic pressure bearing is provided between the dynamic pressure shaft 103 and the dynamic pressure sleeve 104. Therefore, the exhaust mechanism must be configured symmetrically at both ends of the hydrodynamic bearings 106 and 106 with the gap interposed therebetween. As a result, an increase in the size of the component in the axial direction is incurred.
[0005]
An object of the present invention is to provide a pressure-reducing optical deflector that can achieve a compact configuration while ensuring light-load high-speed rotation by a pressure-reducing means.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a radial support portion including a dynamic pressure shaft and a dynamic pressure sleeve, which are rotatably fitted to each other via a dynamic pressure bearing by a herringbone groove or other dynamic pressure generating portion, is provided. In the optical deflector that rotatably supports the rotating mirror and other rotating members in the case,
The case is hermetically formed, the one end of the dynamic pressure sleeve is closed and attached to the rotating member side, the dynamic pressure shaft is cantilevered on the case side, and the dynamic pressure shaft is free of the dynamic pressure shaft. It consists of a spiral groove that feeds air in the end direction, a radial portion that opens to the outer peripheral surface of the dynamic pressure shaft, and a hollow portion that communicates with the radial portion and opens to the outer end along the center of the dynamic pressure shaft. Form an open air communication hole to communicate,
Between the free end of the dynamic pressure shaft and the dynamic pressure sleeve, a shaft end chamber whose volume is changed according to the thrust displacement of the dynamic pressure sleeve is formed, and the hollow space is formed in the shaft end chamber, outside air, and the dynamic pressure shaft. An attenuation passage having a flow path resistance that suppresses a rapid change in the thrust displacement and that is communicated with the portion and is provided with an attenuation member above the radius portion is formed.
Further, the flow path resistance is constituted by a damping member made of sintered metal.
[0007]
In the pressure-reducing optical deflector configured as described above, the gap between the dynamic pressure shaft and the dynamic pressure sleeve communicates with the inside of the case only on the fixed end side of the dynamic pressure shaft. And, since the spiral groove that feeds air toward the free end of the dynamic pressure shaft and the outside air communication hole that opens to the destination side and communicates with the outside air are formed in the radial support portion on the side of the dynamic pressure bearing, The air in the case is discharged through the spiral groove and the outside air communication hole, and the inside of the case is decompressed.
In addition, when the flow path resistance is constituted by a damping member made of sintered metal, a flow proportional resistance corresponding to a circular hole having a diameter of 0.1 mm or less that is difficult to machine according to the mass on the rotating member side, Further, it can be set with high accuracy according to the volume of the shaft end chamber.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a longitudinal sectional view of a pressure reducing optical deflector with a dynamic pressure shaft fixed, showing an embodiment of the present invention. The decompression type optical deflector 1 is configured by rotatably supporting a rotating mirror 4 and other rotating members in a case 2 via a radial support portion 3 by dynamic pressure.
[0009]
The dynamic pressure shaft 5 of the radial support portion 3 is raised and fixed in a cantilever manner at the center portion of the case 2. The radial support portion 3 forms a dynamic pressure generating portion 6 on the illustrated dynamic pressure shaft 5 or forms a dynamic pressure generating portion 6 on the dynamic pressure sleeve 7 to connect the dynamic pressure shaft 5 and the dynamic pressure sleeve 7 to each other. Mates so that it can rotate. The rotating mirror 4 and other rotating members are attached to the dynamic pressure sleeve 7, and the lid member 8 is attached to seal the inside of the case 2. The dynamic pressure generating section 6 forms a dynamic pressure bearing by the herringbone groove 6 formed integrally or separated as shown in the drawing and other various dynamic pressure support means.
[0010]
The dynamic pressure sleeve 7 is formed in a bag shape with one end 7 a closed, and is fitted to a dynamic pressure shaft 5 that is cantilevered to the case 2. A spiral groove 9 for supplying air in the direction of the free end 5a of the dynamic pressure shaft 5 is formed in the radial support portion 3 on the side of the dynamic pressure generating portion 6, and an outside air communication hole 10 is opened on the destination side. The spiral groove 9 is formed in the illustrated dynamic pressure shaft 5 or the dynamic pressure sleeve 7, and the outside air communication hole 10 is formed in the illustrated dynamic pressure shaft 5 or through the dynamic pressure shaft 5 in the dynamic pressure sleeve 7. The spiral groove 9 feeds the air in the case 2 in the direction of the free end 5a and is discharged from the outside air communication hole 10, so that the spiral groove 9 and the outside air communication hole 10 form an exhaust mechanism.
[0011]
The dynamic pressure sleeve 7 includes a thrust magnetic bearing 11 and a rotation drive unit 12 between the outer peripheral case 2 and the outer peripheral case 2. The rotation drive unit 12 includes a magnet 13 as a rotation side, and a coil 14, a yoke 15, a rotation sensor 12a, and the like as a fixed side.
[0012]
Since the pressure-reducing optical deflector 1 having such a configuration closes one end of the dynamic pressure sleeve 7 on the rotating member 4 side and this dynamic pressure sleeve 7 is fitted to the dynamic pressure shaft 5 on the case 2 side, The open end 7b side of the dynamic pressure sleeve 7 is fitted to the fixed end 5b side of the dynamic pressure shaft 5, so that the clearance between the dynamic pressure shaft 5 and the dynamic pressure sleeve 7 is inside the case 2 only at the open end 7b of the dynamic pressure sleeve. Communicate with.
[0013]
Since the exhaust mechanism comprising the spiral groove 9 that feeds air in the direction of the free end 5a of the dynamic pressure shaft 5 fixed to the case 2 and the outside air communication hole 10 that opens to the destination side is formed, the air in the case 2 is Without exhausting the symmetrically arranged exhaust mechanism, the air is discharged through the spiral groove 9 and the outside air communication hole 10 by a single exhaust mechanism, and the inside of the case 2 is decompressed.
[0014]
Therefore, the pressure-reducing optical deflector according to the present invention does not require the exhaust mechanism to be symmetrically arranged on the dynamic pressure shaft, and ensures a light load and high-speed rotation by a single exhaust mechanism with the spiral groove and the outside air communication hole. The configuration can be made compact. Further, if the outside air communication hole 10 is opened to the fixed end 5b side from the dynamic pressure generating portion 6 of the dynamic pressure shaft 5, the outside air acts as a bearing back pressure. Can be secured.
[0015]
The outside air communication hole 10 includes a radius portion 10a that opens to the outer peripheral surface of the dynamic pressure shaft 5, and a hollow portion 10b that communicates with the radius portion 10a and opens to the outer end along the center of the dynamic pressure shaft 5. The hollow portion 10b further penetrates to the other free end 5a and communicates with a shaft end chamber 16 formed by the dynamic pressure sleeve 7 on the free end 5a side.
[0016]
The hollow portion 17 reaching the shaft end chamber 16 causes pressure fluctuations in the shaft end chamber 16 even when accompanied by gas flow in the axial direction by the dynamic pressure bearing 6 such as a herringbone groove and when receiving gas flow by the exhaust mechanism. Therefore, the generation of axial force can be suppressed. When the inside of the case 2 is depressurized by the exhaust mechanism, the external air pressure acting on the shaft end chamber 16 via both the hollow portions 10 b and 17 is changed to the thrust displacement between the dynamic pressure shaft 5 and the dynamic pressure sleeve 7. The thrust force of the corresponding thrust magnetic bearing 11 is balanced.
[0017]
A damping passage is formed by interposing a damping member 18 made of sintered metal or the like that suppresses air flow in either of the hollow portions 10b and 17 (in the illustrated example, the hollow portion 17) reaching the shaft end chamber 16. Accordingly, a filter (not shown) is attached to the opening of the hollow portion 10b.
[0018]
The shaft end chamber 16 has a variable volume corresponding to the thrust displacement of the dynamic pressure sleeve 7 with respect to the dynamic pressure shaft 5, and air flow through the attenuation member 18 is generated according to this thrust displacement operation. By setting the flow resistance to be sufficient to suppress sudden changes in thrust displacement, high-speed thrust displacement due to impact or the like can be suppressed, and at a constant pressure against the slow air flow caused by the exhaust mechanism or dynamic pressure bearing. Since the internal pressure of the shaft end chamber 16 is maintained at a constant external pressure in communication with the motor, the rotation can be stabilized. Further, by forming the damping member with sintered metal, the flow proportional resistance corresponding to a circular hole having a diameter of 0.1 mm or less, which is difficult to machine, is set according to the mass on the rotating member side, and the volume of the shaft end chamber It can be set with high accuracy according to.
[0019]
FIG. 2 is a configuration example of a radial bearing of the pressure reducing optical deflector of FIG. The pressure-reducing optical deflector of the present invention includes a dynamic pressure shaft (A) by a separated herringbone groove in which grooves 21 and 22 are separately formed, a dynamic pressure shaft (B) having a plurality of bearings 23 and 24 according to loads, and the like. Regardless of the closeness or separation of the herringbone groove and the number of bearings, various types of dynamic pressure bearings can be applied. In particular, in the case of a hydrodynamic bearing (C) or the like having a multi-arc cross-sectional dynamic pressure shaft 25 and a dynamic pressure sleeve 26 by an orbital flow without an axial gas flow, the exhaust action of the spiral groove 9 is separated. Thus, the capacity of the damping member 18 can be set.
[0020]
FIG. 3 is a view similar to FIG. 2 of another radial dynamic pressure bearing. It is possible to apply a high-performance circulating fluid dynamic bearing (A) with a dynamic pressure sleeve 32 in which a water drain groove 31 is formed and a dynamic pressure shaft 33 having a multi-arc cross section. In addition, a hydrodynamic bearing (B) having a multi-arc arc cross-sectional shape having directionality and a hydrodynamic shaft 35, and a hydrodynamic shaft 36 and hydrodynamic sleeve 37 having a polygonal cross-section having directionality. Various types of hydrodynamic bearings such as a hydrodynamic bearing (C) can be applied.
[0021]
FIG. 4 is a view similar to FIG. 1 of a pressure-reducing optical deflector rotating with a dynamic pressure shaft. The same members as those described above are denoted by the same reference numerals and description thereof is omitted.
The decompression type optical deflector 41 is configured by rotatably accommodating a rotating member such as the rotary mirror 4 in a sealed case 2 via a radial support portion 42 by dynamic pressure.
[0022]
The radial support portion 42 fits a dynamic pressure sleeve 43 erected at the center of the case 2 and a dynamic pressure shaft 44 on the rotating member side so as to be rotatable. The dynamic pressure generating portion 6 is formed on the illustrated dynamic pressure shaft 44 or the dynamic pressure generating portion 6 is formed on the dynamic pressure sleeve 43 to form a dynamic pressure bearing. The dynamic pressure shaft 44 is integrally fixed to the mounting member 45 in a cantilever manner, the rotating mirror 4 and other rotating members are mounted via the mounting member 45, and the lid member 8 is mounted to form the case 2 in an airtight manner.
[0023]
A spiral groove 9 for feeding air in the direction of the free end 44a of the dynamic pressure shaft 44 is formed in the radial support portion 42 on the side of the dynamic pressure generating portion 6, and the outside air communication hole 10 is opened on the destination side. The spiral groove 9 is formed in the illustrated dynamic pressure shaft 44 or the dynamic pressure sleeve 43, and the outside air communication hole 10 is formed in the illustrated dynamic pressure shaft 44 or through the dynamic pressure shaft 44 in the dynamic pressure sleeve 43. 9 and the outside air communication hole 10 constitute an exhaust mechanism.
[0024]
The mounting member 45 includes a thrust magnetic bearing 11 and a rotation driving unit 12 between the outer peripheral case 2 and the mounting member 45. The rotation drive unit 12 includes a magnet 13 as a rotation side, and a coil 14, a yoke 15, a rotation sensor 12a, and the like as a fixed side.
[0025]
In the pressure reducing optical deflector 41 having such a configuration, the dynamic pressure shaft 44 is attached to the rotating member 4 side in a cantilever manner and is fitted to the dynamic pressure sleeve 43 on the case 2 side. Since the end 43a side is fitted to the fixed end 44b side of the dynamic pressure shaft 44, the gap between the dynamic pressure shaft 44 and the dynamic pressure sleeve 43 communicates with the inside of the case 2 only at the open end 43a.
[0026]
Since the exhaust mechanism comprising the spiral groove 9 that feeds air in the direction of the free end 44a of the dynamic pressure shaft 44 and the outside air communication hole 10 that opens to the destination side is formed on the side of the dynamic pressure bearing, The air is discharged through the spiral groove 9 and the outside air communication hole 10, and the inside of the case is decompressed.
[0027]
Therefore, the pressure-reducing optical deflector according to the present invention does not require the exhaust mechanism to be symmetrically arranged on the dynamic pressure shaft, and ensures a light load and high-speed rotation by a single exhaust mechanism with the spiral groove and the outside air communication hole. The configuration can be made compact. Further, if the outside air communication hole 10 is opened from the dynamic pressure generating portion 6 of the dynamic pressure shaft 44 to the fixed end 44b side, the outside air acts as a bearing back pressure, so that the bearing rigidity can be ensured.
[0028]
When the inside of the case 2 is depressurized by the exhaust mechanism, the external magnetic pressure acting on the dynamic pressure shaft 44 acts in accordance with the thrust displacement between the dynamic pressure shaft 44 and the dynamic pressure sleeve 45. Balance with the thrust force.
[0029]
A shaft end chamber 46 is formed on the free end 44 a side of the dynamic pressure shaft 44 by closing the outside thereof. The shaft end chamber 46 communicates with the outside air side, and an attenuation member 47 for suppressing the air flow is interposed, and is covered with a filter (not shown) as necessary. Thus, the thrust displacement operation can be suppressed by the flow path resistance of the damping member 47 as described above, and the internal pressure of the shaft end chamber 46 can be kept constant by communicating with the outside air at a constant pressure.
[0030]
【The invention's effect】
The reduced pressure optical deflector according to the present invention has the following effects. The hydrodynamic sleeve that forms one side of the radial support part is closed on one end and formed on the rotating member side, and the hydrodynamic shaft that forms the other side is cantilevered on the case side and fitted together. The end side is fitted to the fixed end side of the dynamic pressure shaft. As a result, the gap between the dynamic pressure shaft and the dynamic pressure sleeve communicates with the inside of the case only on the fixed end side of the dynamic pressure shaft. And, since the spiral groove that feeds air toward the free end of the dynamic pressure shaft and the outside air communication hole that opens to the destination side and communicates with the outside air are formed in the radial support portion on the side of the dynamic pressure bearing, The air in the case is discharged through the spiral groove and the outside air communication hole, and the inside of the case is decompressed.
[0031]
Therefore, the pressure-reducing optical deflector of the present invention does not require the exhaust mechanism to be symmetrically arranged on the dynamic pressure axis, and ensures a light and high speed rotation by a single exhaust mechanism with the spiral groove and the outside air communication hole. The configuration can be made compact.
Further, since the outside air communication hole is opened to the fixed end side of the dynamic pressure shaft from the dynamic pressure bearing, the outside air acts as a bearing back pressure through the outside air communication hole, so that the bearing rigidity can be ensured.
Further, a shaft end chamber having a volume corresponding to the thrust displacement between the dynamic pressure shaft and the dynamic pressure sleeve is formed facing the free end of the dynamic pressure shaft, and the above-described shaft is formed between the shaft end chamber and the outside air. Since a damping passage having flow resistance that suppresses sudden changes in thrust displacement is formed, high speed due to impact or the like is caused by flow resistance acting on the air flow in the damping passage due to thrust displacement operation between the dynamic pressure shaft and the dynamic pressure sleeve. The thrust displacement operation is suppressed, and the damping passage communicates with the outside air at a constant pressure. Therefore, the exhaust mechanism is secured by a constant back pressure, and the inner pressure of the shaft end chamber is maintained at the outside air pressure. To stabilize the rotation.
Further, when the flow path resistance is constituted by a damping member made of sintered metal, the flow proportional resistance corresponding to a circular hole having a diameter of 0.1 mm or less, which is difficult to machine, is set according to the mass on the rotating member side. Further, it can be set with high accuracy according to the volume of the shaft end chamber.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a pressure reducing optical deflector having a dynamic pressure shaft fixed according to an embodiment of the present invention. FIG. 2 is a configuration example of a radial bearing of the pressure reducing optical deflector shown in FIG. Fig. 4 is a view similar to Fig. 2 of a radial dynamic pressure bearing. Fig. 4 is a view similar to Fig. 1 of a pressure reducing optical deflector rotating a dynamic pressure shaft. Fig. 5 is a longitudinal sectional view of a conventional pressure reducing optical deflector. Explanation】
1 Depressurizing optical deflector 2 Case 3 Radial support 4 Rotating mirror (rotating member)
5 Dynamic pressure shaft 5a Free end 5b Fixed end 6 Herringbone groove (dynamic pressure generating part)
7 Dynamic pressure sleeve 7a One end 7b Open end 8 Lid member 9 Spiral groove (exhaust mechanism)
10 Outside air communication hole (exhaust mechanism)
10a Radial part 10b Hollow part 16 Shaft end chamber 17 Hollow part 18 Damping member (damping passage)
41 Depressurization type optical deflector 42 Radial support portion 43 Dynamic pressure sleeve 43a Open end 44 Dynamic pressure shaft 44a Free end 44b Fixed end 45 Mounting member 46 Shaft end chamber 47 Damping member (damping passage)

Claims

A radial support part comprising a dynamic pressure shaft and a dynamic pressure sleeve, which are rotatably fitted to each other via a dynamic pressure bearing by a herringbone groove or other dynamic pressure generating part, is provided, and a rotating mirror is provided in the case via the radial support part. In an optical deflector that rotatably supports other rotating members,
The case is hermetically formed, the one end of the dynamic pressure sleeve is closed and attached to the rotating member side, the dynamic pressure shaft is cantilevered on the case side, and the dynamic pressure shaft is free of the dynamic pressure shaft. It consists of a spiral groove that feeds air in the end direction, a radial portion that opens to the outer peripheral surface of the dynamic pressure shaft, and a hollow portion that communicates with the radial portion and opens to the outer end along the center of the dynamic pressure shaft. Form an open air communication hole to communicate,
Between the free end of the dynamic pressure shaft and the dynamic pressure sleeve, a shaft end chamber whose volume is changed according to the thrust displacement of the dynamic pressure sleeve is formed, and inside the dynamic pressure shaft between the shaft end chamber and the outside air. A pressure-reducing optical deflector in which an attenuation passage having a flow path resistance that suppresses an abrupt change in the thrust displacement is formed by communicating with the hollow portion and interposing an attenuation member above the radius portion .

2. The reduced pressure optical deflector according to claim 1, wherein the flow path resistance is constituted by a damping member made of sintered metal.