JP4178371B2

JP4178371B2 - Long mirror support mechanism

Info

Publication number: JP4178371B2
Application number: JP2002184369A
Authority: JP
Inventors: 健宗和; 望井上; 洋一三井
Original assignee: Seiko Epson Corp
Current assignee: Seiko Epson Corp
Priority date: 2002-06-25
Filing date: 2002-06-25
Publication date: 2008-11-12
Anticipated expiration: 2022-06-25
Also published as: JP2004029294A

Description

【０００１】
【発明の属する技術分野】
本発明は、長尺ミラーの支持機構に係り、特に、画像形成装置等の加振源の加振周波数に同調して振動することのない長尺ミラーの支持機構に関するものである。
【０００２】
【従来の技術】
例えば、レーザービームプリンタ等の画像形成装置の画像書き込み露光部には何枚かの長尺ミラーが用いられている。その例を図１３に示す。紙面の裏面側に配置された不図示の光源からの光ビームは折り返しミラー２１により反射されて図の右斜め下方に折り曲げられ、回転軸１２を中心として回転する回転多面鏡１０の偏向反射鏡１１に入射する光ビームａ₁となり、偏向反射鏡１１で左斜め下方に偏向反射された光ビームａ₂は走査光学系２０を経て折り返しミラー２２で今度は図の右斜め下方に折り曲げられ、次の折り返しミラー２３で今度は図の上方へ折り曲げられ、感光ドラム等の被走査面２５上に入射して、紙面に垂直の走査線を描く（例えば特開平７−１６８１１５号公報）。この例では、折り返しミラー２２、２３は図１３の面に垂直に偏向される光ビームａ₂を反射するために、幅が狭く長さの長い長尺ミラーが用いられる。
【０００３】
このような長尺ミラーの支持機構としては、ミラー長手方向の両端付近で、反射面に直角方向に３点で支持、反射面に平行方向に２点で支持するのが一般的である。図１２にこのような長尺ミラー１の従来の支持機構の１例を示す。図１２（ａ）はその支持機構の全体を示す斜視図、図１２（ｂ）は（ａ）の一端Ａでの断面図、図１２（ｃ）は（ａ）の他端Ｂでの断面図、図１２（ｄ）は（ｂ）の変形を示す一端Ａでの断面図である。
【０００４】
幅が狭く長さの長い長尺ミラー１にはその前面２が反射面となっており、基板５上の支持点Ｙ１とＹ２とが長尺ミラー１の反射面２に接する長手方向の１側面の両端位置に点接触しており、その向かい側の側面の支持点Ｙ１とＹ２に対応する位置を、基板５から立った支柱６と７から伸びている板バネ８と９のバネ押圧部Ｔ１とＴ２がバネ押圧しており、支持点Ｙ１とバネ押圧部Ｔ１の間で長尺ミラー１の一端を反射面２に平行方向に位置決め支持しており、支持点Ｙ２とバネ押圧部Ｔ２の間で長尺ミラー１の他端を反射面２に平行方向に位置決め支持している。
【０００５】
また、長尺ミラー１の反射面２は基板５から立っている支柱３と４にその両端位置でそれぞれもたれ掛かっており、支柱３には長尺ミラー１の反射面２の幅方向の両辺近傍で点接触する支持点Ｘ１とＸ２が設けられ、支柱４には長尺ミラー１の反射面２の幅方向の略中央で点接触する支持点Ｘ３が設けられている。そして、基板５の長尺ミラー１の反射面２とは反対側の裏面２’側に長尺ミラー１の両端に対応して立っている支柱６と７から、それぞれ支持点Ｘ１とＸ２、支持点Ｘ３に対応する位置で拡張性バネＳ１、Ｓ２、Ｓ３が長尺ミラー１の裏面２’に押圧しており、支持点Ｘ１と拡張性バネＳ１の間、及び、支持点Ｘ２と拡張性バネＳ２の間で長尺ミラー１の一端を反射面２に直角方向に位置決め支持しており、支持点Ｘ３と拡張性バネＳ３の間で長尺ミラー１の他端を反射面２に直角方向に位置決め支持している。
【０００６】
なお、図１２（ｄ）に示すように、長尺ミラー１の一端を裏面２’から押圧する拡張性バネを支持点Ｘ１、Ｘ２の数に対応した２個とするのではなく、１個の共通の拡張性バネＳ１２とする場合もある。特に、長尺ミラー１の厚み（反射面２の法線方向の厚み）に対して支持点Ｘ１、Ｘ２間の距離が近い場合には、このように１個の共通の拡張性バネＳ１２で構成することが可能である。
【０００７】
この例のように、従来は、長尺ミラーを支持するのに、ミラー長手方向の両端付近で、反射面に直角方向に３点で支持、反射面に平行方向に２点で支持するのが一般的である。
【０００８】
【発明が解決しようとする課題】
ところで、例えばレーザービームプリンタ等の画像形成装置においては、多数の加振源があり、以上のようにミラー両端で長尺ミラーを支持する支持機構の場合の長尺ミラーの共振周波数は、ミラー厚み及びその材質で決まるため、装置内にある駆動系加振源の加振周波数を避けるように共振周波数（固有周波数）を上げて加振源の加振周波数から離すようにする。そのために、一般には長尺ミラーの厚みを厚くする方法がとられる。
【０００９】
しかしながら、長尺ミラーの厚みを上げることはコストアップにつながる。また、長尺ミラーの加工工程においても、反射面の短辺方向の幅に対してミラー厚みが厚すぎると、カット線を入れて割って長尺ミラーを得ることができなくなり、加工方法が制限され、これもコストアップにつながる。
【００１０】
本発明は従来技術のこのような問題点に鑑みてなされたものであり、その目的は、ミラー厚みを上げることなく、簡単な機構で共振周波数を上げて長尺ミラーを使用する装置の加振源の加振周波数を避けることができる長尺ミラーの支持機構を提供することである。
【００１１】
【課題を解決するための手段】
上記目的を達成する本発明の長尺ミラーの支持機構は、幅が狭く長さの長い長尺ミラーの支持機構であって、反射面に直角方向に３点以上の支持点で支持し、反射面に平行方向に２点以上の支持点で支持する長尺ミラーの支持機構において、
反射面に直角方向又は平行方向の支持点の中の少なくとも１点が長尺ミラーの長手方向端部近傍ではない位置に配置されていることを特徴とするものである。
【００１２】
この場合に、反射面に直角方向に支持する点が３点で、反射面に平行方向に支持する点が２点からなり、反射面に直角方向に支持する２点と反射面に平行方向に支持する１点とが長手方向一端近傍ではない位置に配置され、反射面に直角方向に支持する残りの１点と反射面に平行方向に支持する残りの１点とが長手方向他端近傍ではない位置に配置されているものとすることができる。
【００１３】
その場合に、反射面に直角方向に支持する２点と反射面に平行方向に支持する１点との配置位置の長尺ミラーの長手方向一端からの距離をａ、反射面に直角方向に支持する残りの１点と反射面に平行方向に支持する残りの１点との配置位置の長尺ミラーの長手方向他端からの距離をａ、長尺ミラーの長手方向の長さをＬとするとき、
０．１８≦ａ／Ｌ≦０．２６・・・（１）
を満足することが望ましい。
【００１４】
また、反射面に直角方向の支持点は長手方向端部近傍に配置され、反射面に平行方向に支持する支持点の少なくとも１点が長尺ミラーの長手方向端部近傍ではない位置に配置されているものとすることができる。
【００１５】
この場合に、反射面に直角方向に支持する点が３点で、反射面に平行方向に支持する点が２点からなり、反射面に直角方向に支持する２点が長手方向一端近傍に配置され、反射面に直角方向に支持する残りの１点が長手方向他端近傍に配置され、反射面に平行方向に支持する１点が長手方向一端近傍ではない位置に配置され、反射面に平行方向に支持する残りの１点が長手方向他端近傍ではない位置に配置されているものとすることが望ましい。
【００１６】
そして、長手方向一端近傍の反射面に直角方向に支持する２点の配置位置と長手方向他端近傍の反射面に直角方向に支持する残りの１点の配置位置との間の長尺ミラー長手方向の距離をＬ’とし、長手方向一端近傍の反射面に直角方向に支持する２点の配置位置と反射面に平行方向に支持する１点との配置位置と間の長尺ミラー長手方向の距離をａ’、長手方向他端近傍の反射面に直角方向に支持する残りの１点の配置位置と反射面に平行方向に支持する残りの１点との配置位置と間の長尺ミラー長手方向の距離をａ’とするとき、
０．２９≦ａ’／Ｌ’≦０．４・・・（２）
を満足することが望ましい。
【００１７】
これらにおいて、反射面に平行方向に支持する２個の支持点各々に対向して長尺ミラーの反対側に配置するバネ押圧部を、長手方向両端近傍に配置するようにすることもできる。
【００１８】
そして、長手方向一端近傍の反射面に直角方向に支持する２個の支持点各々に対向して長尺ミラーの反対側に配置するバネ押圧部と、反射面に平行方向に支持する１個の支持点に対向して長尺ミラーの反対側であって長手方向一端近傍に配置するバネ押圧部とが一体化され、長手方向他端近傍の反射面に直角方向に支持する残りの１個の支持点に対向して長尺ミラーの反対側に配置するバネ押圧部と、反射面に平行方向に支持する残りの１個の支持点に対向して長尺ミラーの反対側であって長手方向他端近傍に配置するバネ押圧部とが一体化されていることが望ましい。
【００１９】
また、反射面に直角方向に支持する点が３点で、反射面に平行方向に支持する点が２点からなり、反射面に直角方向に支持する１点が長手方向一端近傍に、反射面に直角方向に支持する他の１点が長手方向他端近傍に、反射面に直角方向に支持する残りの１点が長手方向中央近傍に配置され、反射面に平行方向に支持する１点が長手方向一端近傍ではない位置であって、反射面に直角方向に支持する点とは長手方向において異なる位置に配置され、反射面に平行方向に支持する残りの１点が長手方向他端近傍ではない位置であって、反射面に直角方向に支持する点とは長手方向において異なる位置に配置されているものとすることができる。
【００２０】
また、長尺ミラーはその長手方向両端近傍に配置した制限部材間で長手方向に移動可能に取り付けられているか、あるいは、その制限部材間にバネ変倚力で一方の制限部材に押し付けて固定されているものとすることができる。
【００２１】
また、以上において、反射面に直角方向の支持点が長尺ミラーの裏面に対して行われるように構成され、かつ、その支持点に対応するバネ押圧部が反射面の前面側に配置されているようにしてもよい。
【００２２】
これらの本発明の長尺ミラーの支持機構は、例えば画像形成装置の画像書き込み露光部に用いることが望ましい。
【００２３】
本発明においては、反射面に直角方向又は平行方向の支持点の中の少なくとも１点が長尺ミラーの長手方向端部近傍ではない位置に配置されているので、長尺ミラーの共振周波数を上げて加振源の加振周波数を避け、また、摩擦等により振動の減衰を早めることができる。
【００２４】
【発明の実施の形態】
以下に、本発明の長尺ミラーの支持機構の実施例を説明する。
【００２５】
実施例の説明の前に、今後の説明を容易にするための図面の記号について説明する。図１１は、図１２の従来の長尺ミラーの支持機構を説明するための図であり、図１１（ａ）は長尺ミラー１を反射面２側から見た図、図１１（ｂ）は長尺ミラー１をその裏面２’側から見た図、図１１（ｃ）は（ａ）の断面１を矢印側に見た図、図１１（ｄ）は（ａ）の断面２を矢印側に見た図である。この図１１と図１２を比較して明らかなように、支持点Ｘ１、Ｘ２、Ｘ３、Ｙ１、Ｙ２等は太い直線矢印で示し、その矢印先端が支持点となる。また、バネ押圧部Ｔ１、Ｔ２、Ｓ１、Ｓ２、Ｓ３等はジグザグ矢印で示し、その矢印先端がバネ押圧部となる。さらに、●（黒丸）は支持点Ｘ１、Ｘ２、Ｘ３、Ｙ１、Ｙ２等を垂直に見た図、○（白丸）はバネ押圧部Ｔ１、Ｔ２、Ｓ１、Ｓ２、Ｓ３等を垂直に見た図である。
【００２６】
図１に本発明の第１の実施例の長尺ミラー１の支持機構を示す。図１（ａ）は長尺ミラー１を反射面２側から見た図、図１（ｂ）は長尺ミラー１をその裏面２’側から見た図、図１（ｃ）は（ａ）の断面１を矢印側に見た図、図１（ｄ）は（ａ）の断面２を矢印側に見た図、図１（ｅ）は（ａ）の断面３を矢印側に見た図である。この実施例の基本原理は、長尺ミラー１の反射面２に直角方向では３点Ｘ１、Ｘ２、Ｘ３で支持、反射面２に平行方向では２点Ｙ１、Ｙ２で支持するが、反射面２に直角方向又は平行方向の支持点Ｘ１、Ｘ２、Ｘ３、Ｙ１、Ｙ２の中の少なくとも１点、図の場合は反射面２に平行方向の支持点Ｙ２、を長尺ミラー１の長手方向端部近傍ではない中間の位置に配置して、長尺ミラー１の共振周波数を上げて加振源の加振周波数を避けるようにするものである。なお、本発明において、以下、長手方向端部近傍とは、長尺ミラーの長手方向端面からその長尺ミラーの長手方向長さの５％の距離までの間を意味するものとする。
【００２７】
この実施例を説明すると、幅が狭く長さの長い長尺ミラー１の反射面２に接する長手方向の１側面の一端位置に支持点Ｙ１が点接触しており、また、その同じ側面の他端から中央寄りの位置に別の支持点Ｙ２が点接触しており、支持点Ｙ１、Ｙ２の向かい側の側面の支持点Ｙ１とＹ２に対応する位置をそれぞれバネ押圧部Ｔ１とＴ２がバネ押圧しており、支持点Ｙ１とバネ押圧部Ｔ１の間で長尺ミラー１の一端を反射面２に平行方向に位置決め支持しており、支持点Ｙ２とバネ押圧部Ｔ２の間で長尺ミラー１の他端から中央寄りの位置で反射面２に平行方向に位置決め支持している。
【００２８】
また、長尺ミラー１の反射面２には、その長手方向の支持点Ｙ１が位置する端部位置の短辺方向両辺近傍で支持点Ｘ１とＸ２が点接触しており、また、反対側の端部位置の短辺方向の略中央で支持点Ｘ３が点接触しており、長尺ミラー１の反射面２とは反対側の裏面２’の支持点Ｘ１、Ｘ２、Ｘ３に対応する位置をそれぞれバネ押圧部Ｓ１、Ｓ２、Ｓ３がバネ押圧しており、支持点Ｘ１とバネ押圧部Ｓ１の間、及び、支持点Ｘ２とバネ押圧部Ｓ２の間で長尺ミラー１の一端を反射面２に直角方向に位置決め支持しており、支持点Ｘ３とバネ押圧部Ｓ３の間で長尺ミラー１の他端を反射面２に直角方向に位置決め支持している。
【００２９】
このような構成により、長尺ミラー１の共振周波数を上げることができ、また、摩擦等により振動の減衰を早めることができる効果がある。
【００３０】
図２に本発明の第２の実施例の長尺ミラー１の支持機構を示す。図２（ａ）は長尺ミラー１を反射面２側から見た図、図２（ｂ）は長尺ミラー１をその裏面２’側から見た図、図２（ｃ）は（ａ）の断面１を矢印側に見た図、図２（ｄ）は（ａ）の断面２を矢印側に見た図である。この実施例の基本原理は、長尺ミラー１の反射面２に直角方向では３点Ｘ１、Ｘ２、Ｘ３で支持、反射面２に平行方向では２点Ｙ１、Ｙ２で支持するが、何れの支持点Ｘ１、Ｘ２、Ｘ３、Ｙ１、Ｙ２も長手方向端部近傍ではない中間の２か所の何れかの位置に配置して、長尺ミラー１の共振周波数を上げて加振源の加振周波数を避けるようにするものである。
【００３１】
この実施例を説明すると、幅が狭く長さの長い長尺ミラー１の反射面２に接する長手方向の１側面の一端から中央寄りの距離ａ１の位置に支持点Ｙ１が点接触しており、また、その同じ側面の他端から中央寄りの距離ａ２の位置に別の支持点Ｙ２が点接触しており、支持点Ｙ１、Ｙ２の向かい側の側面の支持点Ｙ１とＹ２に対応する位置をそれぞれバネ押圧部Ｔ１とＴ２がバネ押圧しており、支持点Ｙ１とバネ押圧部Ｔ１の間で長尺ミラー１の一端から中央寄りの位置で反射面２に平行方向に位置決め支持しており、支持点Ｙ２とバネ押圧部Ｔ２の間で長尺ミラー１の他端から中央寄りの位置側で反射面２に平行方向に位置決め支持している。
【００３２】
また、長尺ミラー１の反射面２には、その長手方向の支持点Ｙ１が位置する一端から中央寄りの距離ａ１の位置の短辺方向両辺近傍で支持点Ｘ１とＸ２が点接触しており、また、反対側の端部から中央寄りの距離ａ２の位置の短辺方向の一辺（支持点Ｙ２側の辺）近傍で支持点Ｘ３が点接触しており、長尺ミラー１の反射面２とは反対側の裏面２’の支持点Ｘ１、Ｘ２、Ｘ３に対応する位置をそれぞれバネ押圧部Ｓ１、Ｓ２、Ｓ３がバネ押圧しており、支持点Ｘ１とバネ押圧部Ｓ１の間、及び、支持点Ｘ２とバネ押圧部Ｓ２の間で長尺ミラー１の一端から中央寄りの位置で反射面２に直角方向に位置決め支持しており、支持点Ｘ３とバネ押圧部Ｓ３の間で長尺ミラー１の他端から中央寄りの位置側で反射面２に直角方向に位置決め支持している。
【００３３】
この構成において、長尺ミラー１を矩形として、その長手方向の長さをＬとし、Ｌ＝１８０ｍｍ、短辺方向の幅１０ｍｍ、長尺ミラー１の厚み５ｍｍ、長尺ミラー１の基材のヤング率６３．７ＧＰａ、密度２．５×１０³ｋｇ／ｍ³、ポアソン比０．２３とし、ａ１＝ａ２＝ａとした場合の、ａ／Ｌと長尺ミラー１の共振周波数（Ｈｚ）との関係を求めると、図４のようになる。
【００３４】
図４から、ａ／Ｌ＝０．２２近傍に共振周波数のピークがあることが分かる。そして、この図から、少なくとも、
０．１８≦ａ／Ｌ≦０．２６・・・（１）
を満足することが、加振源の加振周波数を避ける上で望ましいことが分かる。
【００３５】
このような構成により、長尺ミラー１の共振周波数を上げながら、長尺ミラー１の平面度を損なわずに反射面位置精度を高く保つことができる効果がある。
【００３６】
図３に本発明の第３の実施例の長尺ミラー１の支持機構を示す。図３（ａ）は長尺ミラー１を反射面２側から見た図、図３（ｂ）は長尺ミラー１をその裏面２’側から見た図、図３（ｃ）は（ａ）の断面１を矢印側に見た図、図３（ｄ）は（ａ）の断面２を矢印側に見た図、図３（ｅ）は（ａ）の断面３を矢印側に見た図、図３（ｆ）は（ａ）の断面４を矢印側に見た図である。この実施例の基本原理は、長尺ミラー１の反射面２に直角方向では３点Ｘ１、Ｘ２、Ｘ３で支持、反射面２に平行方向では２点Ｙ１、Ｙ２で支持するが、反射面２に直角方向の支持点Ｘ１、Ｘ２、Ｘ３は長尺ミラー１の長手方向両端近傍に配置し、他方、反射面２に平行方向の支持点Ｙ１、Ｙ２は長尺ミラー１の長手方向端部近傍ではない中間の２か所の何れかの位置に配置して、長尺ミラー１の共振周波数をより上げて加振源の加振周波数を避けるようにするものである。
【００３７】
この実施例を説明すると、長尺ミラー１の反射面２には、その長手方向の一端近傍の短辺方向両辺近傍で支持点Ｘ１とＸ２が点接触しており、また、その長手方向の他端近傍の短辺方向の略中央で支持点Ｘ３が点接触しており、長尺ミラー１の反射面２とは反対側の裏面２’の支持点Ｘ１、Ｘ２、Ｘ３に対応する位置をそれぞれバネ押圧部Ｓ１、Ｓ２、Ｓ３がバネ押圧しており、支持点Ｘ１とバネ押圧部Ｓ１の間、及び、支持点Ｘ２とバネ押圧部Ｓ２の間で長尺ミラー１の一端を反射面２に直角方向に位置決め支持しており、支持点Ｘ３とバネ押圧部Ｓ３の間で長尺ミラー１の他端を反射面２に直角方向に位置決め支持している。
【００３８】
そして、この長尺ミラー１の長手方向の支持点Ｘ１、Ｘ２の位置と支持点Ｘ３の位置との間の距離をＬ’とする。
【００３９】
また、長尺ミラー１の反射面２に接する長手方向の１側面の支持点Ｘ１、Ｘ２の位置から中央寄りの距離ａ１’の位置に支持点Ｙ１が点接触しており、また、その同じ側面の支持点Ｘ３の位置から中央寄りの距離ａ２’の位置に別の支持点Ｙ２が点接触しており、支持点Ｙ１、Ｙ２の向かい側の側面の支持点Ｙ１とＹ２に対応する位置をそれぞれバネ押圧部Ｔ１とＴ２がバネ押圧しており、支持点Ｙ１とバネ押圧部Ｔ１の間で長尺ミラー１の一端から中央寄りの位置で反射面２に平行方向に位置決め支持しており、支持点Ｙ２とバネ押圧部Ｔ２の間で長尺ミラー１の他端から中央寄りの位置側で反射面２に平行方向に位置決め支持している。
【００４０】
この構成において、長尺ミラー１を矩形として、Ｌ’＝１８０ｍｍ、短辺方向の幅１０ｍｍ、長尺ミラー１の厚み５ｍｍ、長尺ミラー１の基材のヤング率６３．７ＧＰａ、密度２．５×１０³ｋｇ／ｍ³、ポアソン比０．２３とし、ａ１’＝ａ２’＝ａ’とした場合の、ａ’／Ｌ’と長尺ミラー１の共振周波数（Ｈｚ）との関係を求めると、図５のようになる。
【００４１】
図５から、ａ’／Ｌ’＝０．３３近傍に共振周波数のピークがあることが分かる。そして、この図から、少なくとも、
０．２９≦ａ’／Ｌ’≦０．４・・・（２）
を満足することが、加振源の加振周波数を避ける上で望ましいことが分かる。
【００４２】
このような構成により、反射面２の支持点をミラー端部に配置することで、長尺ミラー１を支持するための支持部材で反射面を遮ることなく反射面２を容易に受けることができ、かつ、共振周波数を上げるか、あるいは、摩擦等により減衰を早めることができる効果がある。
【００４３】
以上の実施例は何れも、バネ押圧部Ｓ１、Ｓ２、Ｓ３、Ｔ１、Ｔ２は何れも対応する支持点Ｘ１、Ｘ２、Ｘ３、Ｙ１、Ｙ２に対向した対応位置に設けてある。しかし、図６に示す本発明の第４の実施例の長尺ミラー１の支持機構においては、反射面２に平行方向に位置決め支持している支持点Ｙ１、Ｙ２に対応するバネ押圧部Ｔ１、Ｔ２は対応する対向位置には設けず、長手方向端部近傍のバネ押圧部Ｓ１とＳ２、Ｓ３の位置に設けている。
【００４４】
この実施例を示す図６（ａ）は長尺ミラー１を反射面２側から見た図、図６（ｂ）は長尺ミラー１をその裏面２’側から見た図、図６（ｃ）は（ａ）の断面１を矢印側に見た図、図６（ｄ）は（ａ）の断面２を矢印側に見た図、図６（ｅ）は（ａ）の断面３を矢印側に見た図、図６（ｆ）は（ａ）の断面４を矢印側に見た図である。この実施例の支持点Ｘ１、Ｘ２、Ｘ３、Ｙ１、Ｙ２の位置は図３の実施例と同じであり、バネ押圧部Ｓ１、Ｓ２、Ｓ３も図３の実施例と同じである。そして、支持点Ｙ１、Ｙ２に対応するバネ押圧部Ｔ１、Ｔ２は、長尺ミラー１の長手方向両端部近傍のそれぞれバネ押圧部Ｓ１とＳ２、バネ押圧部Ｓ３と同じ位置の支持点Ｙ１、Ｙ２に対向する側面端部近傍に設けており、支持点Ｙ１とそれから距離ａ１’ずれた端部のバネ押圧部Ｔ１の間で長尺ミラー１の一端を反射面２に平行方向に位置決め支持しており、支持点Ｙ２とそれから距離ａ１’ずれた端部のバネ押圧部Ｔ２の間で長尺ミラー１の他端を反射面２に平行方向に位置決め支持している。
【００４５】
この実施例においては、バネ押圧部Ｓ１、Ｓ２、Ｓ３、Ｔ１、Ｔ２を全て長尺ミラー１の長手方向両端に配置できるので、反射面２に直角方向と平行方向のバネ押圧部材を各端部で一体化でき部品点数が減らせるメリットがある。
【００４６】
この実施例においても、ａ’／Ｌ’と長尺ミラー１の共振周波数（Ｈｚ）との関係は図５と同様になり、ａ’／Ｌ’＝０．３３近傍に共振周波数のピークがある。そして、式（２）を満足することが、加振源の加振周波数を避ける上で望ましい。
【００４７】
このような構成により、反射面２の支持点をミラー端部に配置することで、長尺ミラー１を支持するための支持部材で反射面を遮ることなく反射面２を容易に受けながら、平面度を損なうことなく長尺ミラー１を支持し、共振周波数を上げることができる効果がある。
【００４８】
図７に本発明の第５の実施例の長尺ミラー１の支持機構を示す。図７（ａ）は長尺ミラー１を反射面２側から見た図、図７（ｂ）は長尺ミラー１をその裏面２’側から見た図、図７（ｃ）は（ａ）の断面１、断面５を矢印側に見た図、図７（ｄ）は（ａ）の断面２、断面４を矢印側に見た図、図７（ｅ）は（ａ）の断面３を矢印側に見た図である。この実施例の基本原理は、長尺ミラー１の反射面２に直角方向では３点Ｘ１、Ｘ２、Ｘ３で支持、反射面２に平行方向では２点Ｙ１、Ｙ２で支持するが、反射面２に直角方向の支持点Ｘ１、Ｘ３は長尺ミラー１の長手方向両端近傍に配置し、反射面２に直角方向の支持点Ｘ２は長尺ミラー１の長手方向中央近傍に配置し、反射面２に平行方向の支持点Ｙ１、Ｙ２は長尺ミラー１の長手方向端部近傍ではない中間の２か所に配置し、しかも、全ての支持点Ｘ１、Ｘ２、Ｘ３、Ｙ１、Ｙ２の長尺ミラー１の長手方向の位置を異ならせて５つの位置で支持するようにして、長尺ミラー１の共振周波数をより上げて加振源の加振周波数を避けるようにするものである。
【００４９】
この実施例を説明すると、幅が狭く長さの長い長尺ミラー１の反射面２に接する長手方向の１側面の一端から約１／４の位置に支持点Ｙ１が点接触しており、また、その同じ側面の他端から約１／４の位置に支持点Ｙ２が点接触しており、支持点Ｙ１、Ｙ２の向かい側の側面の支持点Ｙ１とＹ２に対応する位置をそれぞれバネ押圧部Ｔ１とＴ２がバネ押圧しており、支持点Ｙ１とバネ押圧部Ｔ１の間で長尺ミラー１の一端から中央寄りの位置で反射面２に平行方向に位置決め支持しており、支持点Ｙ２とバネ押圧部Ｔ２の間で長尺ミラー１の他端から中央寄りの位置側で反射面２に平行方向に位置決め支持している。
【００５０】
また、長尺ミラー１の反射面２には、その長手方向の一端近傍の短辺方向一辺近傍で支持点Ｘ１が点接触しており、他端近傍の短辺方向一辺近傍で支持点Ｘ３が点接触しており、その長手方向の略中央の短辺方向他辺近傍で支持点Ｘ２が点接触しており、長尺ミラー１の反射面２とは反対側の裏面２’の支持点Ｘ１、Ｘ２、Ｘ３に対応する位置をそれぞれバネ押圧部Ｓ１、Ｓ２、Ｓ３がバネ押圧しており、支持点Ｘ１とバネ押圧部Ｓ１の間、支持点Ｘ２とバネ押圧部Ｓ２の間、及び、支持点Ｘ３とバネ押圧部Ｓ３の間で長尺ミラー１のそれぞれ一端、中央、他端で反射面２に直角方向に位置決め支持している。
【００５１】
このような構成により、共振周波数を最も高く上げることができる効果がある。
【００５２】
さて、本発明の上記のような長尺ミラー１の支持機構において、長尺ミラー１の長手方向両端での長尺ミラー１の固定方法あるいは取り付け方法については触れてこなかったが、図１２（ａ）と同様な従来の長尺ミラー１の支持機構の図を用いて、その固定方法あるいは取り付け方法の例を説明する。図８（ａ）はその支持機構の全体を示す斜視図であり、この図においては、本発明に基づいて、長尺ミラー１の反射面２に直角方向の支持点Ｘ１、Ｘ２、Ｘ３、反射面２に平行方向の支持点Ｙ１、Ｙ２の何れかが長尺ミラーの長手方向端部近傍ではない位置に図示上は配置されてはいないが、本発明に基づいて、その中の少なくとも１点が長尺ミラー１の長手方向端部近傍ではない位置に配置されるものとする。
【００５３】
このような構成において、長尺ミラー１を長手方向に固定するには、図８（ｂ）に示すように、制限部材３１と３３の間に拡張性バネ３５と長尺ミラー１を介在させて拡張性バネ３５の変倚力で一方の制限部材３１へ長尺ミラー１を長手方向に押し付けて移動しないように固定すればよい。あるいは、図８（ｃ）に示すように、単に制限部材３２と３４の間に自由に落とし込んである程度長手方向に移動可能に取り付けるようにしても、支持点Ｘ１、Ｘ２、Ｘ３により反射面２の面精度は保たれるので問題はない。なお、図８（ｂ）、（ｃ）は図８（ａ）の太い矢印方向に長尺ミラー１を見た図である。
【００５４】
以上の説明において、長尺ミラー１の反射面２に直角方向の支持点Ｘ１、Ｘ２、Ｘ３については、反射面２の前面に接触して３点支持により面出しするものとしていたが、これら支持点Ｘ１、Ｘ２、Ｘ３を長尺ミラー１の裏面２’に接触するようにし、反射面２の前面にはこれら支持点Ｘ１、Ｘ２、Ｘ３に対応するバネ押圧部を接触させ、そのバネ押圧部により反射面２に直角方向にバネ押圧するように構成してもよい。その例を図９の斜視図に示す。この配置においては、基板５上の長尺ミラー１の両端から中央寄りの２つの位置に配置された支持点Ｙ１、Ｙ２により反射面２に平行方向に支持されており、その支持点Ｙ１、Ｙ２の向かい側の側面の支持点Ｙ１とＹ２に対応する位置をそれぞれ板バネ８’、９’のバネ押圧部Ｔ１、Ｔ２がバネ押圧している。長尺ミラー１の裏面２’は基板５から立っている支柱３と４にその両端位置でそれぞれもたれ掛かっており、支柱３には長尺ミラー１の裏面２’の幅方向の両辺近傍で点接触する支持点Ｘ１とＸ２が設けられ、支柱４には長尺ミラー１の裏面２’の幅方向の略中央で点接触する支持点Ｘ３（図９では見えない）が設けられている。そして、長尺ミラー１の反射面２の支持点Ｘ１とＸ２に対応する１つの位置を板バネ８のバネ押圧部Ｓ１２（図１２（ｄ）参照）がバネ押圧しており、また、反射面２の支持点Ｘ３に対応する位置を板バネ９のバネ押圧部Ｓ３バネ押圧している。なお、板バネ８と８’は支柱３に、また、板バネ９と９’は支柱４にその一端が取り付けられ、バネ押圧部Ｓ１２が支持点Ｘ１とＸ２に対して、また、バネ押圧部Ｓ３が支持点Ｘ３に対して押圧するようになっており、そのため、板バネ８と９は長尺ミラー１を裏面２’側から抱え込むような形状に形成されている。
【００５５】
次に、支持点Ｘ１、Ｘ２、Ｘ３、Ｙ１、Ｙ２等、バネ押圧部Ｓ１、Ｓ２、Ｓ３、Ｓ１２、Ｔ１、Ｔ２等の具体的構成について例示する。反射面２、裏面２’に接触する支持点Ｘ１、Ｘ２、Ｘ３等については、図１２、図９に示すように、基板５から立つ支柱３、４に設けられた点接触する支持点からなっていてもよく、あるい、図１０に断面を示すように、基板５側の支持点Ｘ２は基板５に直接設けた支持点からなり、基板５から離れる側の支持点Ｘ１は長尺ミラー１を裏面２’側から抱え込むように裏面２側の支柱３頭部に取り付けた支持部材３６の先端を支持点としてもよい。また、バネ押圧部Ｓ１、Ｓ２、Ｓ３、Ｓ１２、Ｔ１、Ｔ２等は図８、図９、図１２に示すように、板バネ８、９、８’、９’のように一部を板バネで構成してもよいが、図１０に示すように、全てを拡張性バネ（螺旋バネ）で構成することもできる。
【００５６】
以上、本発明の長尺ミラーの支持機構を実施例に基づいて説明してきたが、本発明はこれらに限定されず、種々の変形が可能である。また、本発明の長尺ミラーの支持機構は、図１３に例示したようなレーザービームプリンタ等の画像形成装置の画像書き込み露光部以外に種々の用途、特に加振源を持つ装置の長尺ミラーの支持機構に適用することができる。
【００５７】
【発明の効果】
以上の説明から明らかなように、本発明の長尺ミラーの支持機構によると、反射面に直角方向又は平行方向の支持点の中の少なくとも１点が長尺ミラーの長手方向端部近傍ではない位置に配置されているので、長尺ミラーの共振周波数を上げて加振源の加振周波数を避け、また、摩擦等により振動の減衰を早めることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施例の長尺ミラーの支持機構を示す図である。
【図２】本発明の第２の実施例の長尺ミラーの支持機構を示す図である。
【図３】本発明の第３の実施例の長尺ミラーの支持機構を示す図である。
【図４】第２の実施例の共振周波数特性を示す図である。
【図５】第３の実施例の共振周波数特性を示す図である。
【図６】本発明の第４の実施例の長尺ミラーの支持機構を示す図である。
【図７】本発明の第５の実施例の長尺ミラーの支持機構を示す図である。
【図８】本発明の長尺ミラーの支持機構における長尺ミラーの長手方向の固定方法、取り付け方法の例を説明するための図である。
【図９】本発明の長尺ミラーの支持機構の変形例を示す斜視図である。
【図１０】本発明における支持点、バネ押圧部の構成について例示するための図である。
【図１１】本発明の実施例の説明に用いる記号を図１２に基づいて説明するするための図である。
【図１２】従来の長尺ミラーの支持機構の１例を説明するための図である。
【図１３】本発明の長尺ミラーの支持機構が適用可能な画像形成装置の画像書き込み露光部の構成例を説明するための図である。
【符号の説明】
１…長尺ミラー
２…長尺ミラーの前面（反射面）
２’…長尺ミラーの裏面
３、４、６、７…支柱
５…基板
８、９、８’、９’…板バネ
１０…回転多面鏡
１１…偏向反射鏡
１２…回転軸
２０…走査光学系
２１、２２、２３…折り返しミラー
２５…被走査面
３１、３２、３３、３４…制限部材
３５…拡張性バネ
３６…支持部材
ａ₁、ａ₂…光ビーム
Ｘ１、Ｘ２、Ｘ３、Ｙ１、Ｙ２…支持点
Ｓ１、Ｓ２、Ｓ３、Ｓ１２…拡張性バネ（バネ押圧部）
Ｔ１、Ｔ２…バネ押圧部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a long mirror support mechanism, and more particularly to a long mirror support mechanism that does not vibrate in synchronization with an excitation frequency of an excitation source such as an image forming apparatus.
[0002]
[Prior art]
For example, several long mirrors are used in an image writing exposure unit of an image forming apparatus such as a laser beam printer. An example is shown in FIG. A light beam from a light source (not shown) arranged on the back side of the paper surface is reflected by a folding mirror 21 and is bent obliquely downward and rightward in the drawing, and the deflecting reflecting mirror 11 of the rotating polygonal mirror 10 that rotates about the rotating shaft 12. Light beam a incident on ₁ The light beam a deflected and reflected to the lower left by the deflecting mirror 11 ₂ Is bent by the folding mirror 22 through the scanning optical system 20 and obliquely downward to the right in the figure, and is then folded up by the next folding mirror 23 and incident on the surface to be scanned 25 such as a photosensitive drum. Then, a scanning line perpendicular to the paper surface is drawn (for example, JP-A-7-168115). In this example, the folding mirrors 22 and 23 are light beams a deflected perpendicularly to the plane of FIG. ₂ In order to reflect the light, a long mirror having a narrow width and a long length is used.
[0003]
As a support mechanism for such a long mirror, it is general to support at three points in the direction perpendicular to the reflecting surface and at two points in the direction parallel to the reflecting surface near both ends in the longitudinal direction of the mirror. FIG. 12 shows an example of a conventional support mechanism for such a long mirror 1. 12A is a perspective view showing the entire support mechanism, FIG. 12B is a cross-sectional view at one end A of FIG. 12A, and FIG. 12C is a cross-sectional view at the other end B of FIG. FIG. 12D is a cross-sectional view at one end A showing the deformation of FIG.
[0004]
The long mirror 1 having a narrow width and a long length has a front surface 2 as a reflecting surface, and support points Y1 and Y2 on the substrate 5 are on one side surface in the longitudinal direction in contact with the reflecting surface 2 of the long mirror 1. And the spring pressing portions T1 of the leaf springs 8 and 9 extending from the columns 6 and 7 standing from the substrate 5 at positions corresponding to the supporting points Y1 and Y2 on the opposite side surface. T2 is spring-pressed, and one end of the long mirror 1 is positioned and supported in a direction parallel to the reflecting surface 2 between the support point Y1 and the spring-pressing portion T1, and between the support point Y2 and the spring-pressing portion T2. The other end of the long mirror 1 is positioned and supported in parallel to the reflecting surface 2.
[0005]
Further, the reflecting surface 2 of the long mirror 1 leans against the pillars 3 and 4 standing from the substrate 5 at both end positions, and the pillar 3 is in the vicinity of both sides in the width direction of the reflecting surface 2 of the long mirror 1. The support points X1 and X2 that make point contact are provided, and the support 4 is provided with a support point X3 that makes point contact substantially at the center of the reflecting surface 2 of the long mirror 1 in the width direction. The support points X1 and X2 are respectively supported from the support columns 6 and 7 standing on the back surface 2 ′ side opposite to the reflection surface 2 of the long mirror 1 of the substrate 5 corresponding to both ends of the long mirror 1. The expandable springs S1, S2, S3 are pressed against the back surface 2 'of the long mirror 1 at a position corresponding to the point X3, and between the support point X1 and the expandable spring S1, and between the support point X2 and the expandable spring. One end of the long mirror 1 is positioned and supported at right angles to the reflecting surface 2 between S2 and the other end of the long mirror 1 is perpendicular to the reflecting surface 2 between the support point X3 and the expandable spring S3. Positioning is supported.
[0006]
In addition, as shown in FIG. 12D, the expandable spring that presses one end of the long mirror 1 from the back surface 2 ′ is not two pieces corresponding to the number of support points X1 and X2, but one piece. A common expandable spring S12 may be used. In particular, when the distance between the support points X1 and X2 is close to the thickness of the long mirror 1 (the thickness in the normal direction of the reflecting surface 2), the single expandable spring S12 is used in this way. Is possible.
[0007]
As in this example, conventionally, to support a long mirror, it is supported at three points in a direction perpendicular to the reflecting surface and at two points in a direction parallel to the reflecting surface near both ends in the longitudinal direction of the mirror. It is common.
[0008]
[Problems to be solved by the invention]
By the way, in an image forming apparatus such as a laser beam printer, there are a large number of vibration sources, and the resonance frequency of the long mirror in the case of the support mechanism that supports the long mirror at both ends of the mirror as described above is the mirror thickness. Therefore, the resonance frequency (natural frequency) is increased so as to avoid the excitation frequency of the drive system excitation source in the apparatus so as to be separated from the excitation frequency of the excitation source. Therefore, generally, a method of increasing the thickness of the long mirror is taken.
[0009]
However, increasing the thickness of the long mirror leads to an increase in cost. Also in the long mirror processing process, if the mirror thickness is too thick relative to the width of the short side of the reflecting surface, it will not be possible to obtain a long mirror by cutting the cut line, limiting the processing method. This also increases costs.
[0010]
The present invention has been made in view of such problems of the prior art, and its object is to increase the resonance frequency with a simple mechanism without increasing the mirror thickness, and to vibrate an apparatus using a long mirror. It is to provide a support mechanism for a long mirror that can avoid the excitation frequency of the source.
[0011]
[Means for Solving the Problems]
The long mirror support mechanism of the present invention that achieves the above object is a long mirror support mechanism that has a narrow width and a long length, and is supported at three or more support points in a direction perpendicular to the reflecting surface and reflected. In the support mechanism of the long mirror that supports at two or more support points in the direction parallel to the surface,
It is characterized in that at least one of the support points perpendicular to or parallel to the reflecting surface is arranged at a position that is not near the longitudinal end of the long mirror.
[0012]
In this case, there are three points that are supported in the direction perpendicular to the reflecting surface, two points that are supported in the direction parallel to the reflecting surface, and two points that are supported in the direction perpendicular to the reflecting surface and in a direction parallel to the reflecting surface. One point to be supported is arranged at a position that is not near one end in the longitudinal direction, and the other point that is supported in a direction perpendicular to the reflecting surface and the other point that is supported in a direction parallel to the reflecting surface is near the other end in the longitudinal direction. It may be arranged at a position not present.
[0013]
In this case, the distance from the longitudinal end of the long mirror at the position of the two points that are supported perpendicularly to the reflecting surface and the one point that is supported parallel to the reflecting surface is a, and the distance perpendicular to the reflecting surface is supported. The distance from the other longitudinal end of the long mirror at the arrangement position of the remaining one point to be supported and the remaining one point supported in the direction parallel to the reflecting surface is a, and the longitudinal length of the long mirror is L. When
0.18 ≦ a / L ≦ 0.26 (1)
It is desirable to satisfy
[0014]
Further, the support point perpendicular to the reflecting surface is arranged in the vicinity of the end in the longitudinal direction, and at least one of the supporting points supported in the direction parallel to the reflecting surface is arranged in a position not near the end of the long mirror in the longitudinal direction. Can be.
[0015]
In this case, there are three points that support the reflecting surface in a direction perpendicular to the reflecting surface, two points that support the reflecting surface in the direction parallel to the reflecting surface, and two points that support the reflecting surface in the direction perpendicular to the reflecting surface are arranged near one end in the longitudinal direction. The remaining one point that is supported in the direction perpendicular to the reflecting surface is disposed in the vicinity of the other end in the longitudinal direction, and the one point that is supported in the direction parallel to the reflecting surface is disposed not in the vicinity of the one end in the longitudinal direction. It is desirable that the remaining one point supported in the direction is arranged at a position that is not near the other end in the longitudinal direction.
[0016]
Then, the length of the long mirror between the arrangement position of the two points that are supported in the direction perpendicular to the reflection surface near one end in the longitudinal direction and the other one arrangement position that is supported in the direction perpendicular to the reflection surface near the other end in the longitudinal direction. The distance in the direction is L ′, and the length of the long mirror in the longitudinal direction between the arrangement position of two points that are supported in a direction perpendicular to the reflection surface near one end in the longitudinal direction and the arrangement position of one point that is supported in a direction parallel to the reflection surface The length of the long mirror between the disposition position of the remaining point that is supported by the distance a ′ and the reflection surface near the other end in the longitudinal direction in the direction perpendicular to the disposition position of the remaining point that is supported in the direction parallel to the reflection surface When the distance in the direction is a ′,
0.29 ≦ a ′ / L ′ ≦ 0.4 (2)
It is desirable to satisfy
[0017]
In these, it is also possible to arrange the spring pressing portions arranged on the opposite side of the long mirror so as to face each of the two supporting points supported in the direction parallel to the reflecting surface in the vicinity of both ends in the longitudinal direction.
[0018]
Then, a spring pressing portion disposed on the opposite side of the long mirror so as to face each of the two support points that are supported in a direction perpendicular to the reflection surface near one end in the longitudinal direction, and one support that is parallel to the reflection surface A spring pressing portion disposed on the opposite side of the long mirror and in the vicinity of one end in the longitudinal direction facing the support point is integrated, and the remaining one piece supported in the direction perpendicular to the reflecting surface near the other end in the longitudinal direction. A spring pressing portion disposed on the opposite side of the long mirror facing the support point, and a longitudinal direction opposite to the long mirror opposite to the remaining one support point supported in a direction parallel to the reflecting surface It is desirable that the spring pressing portion disposed in the vicinity of the other end is integrated.
[0019]
Further, there are three points that are supported in the direction perpendicular to the reflecting surface, two points that are supported in the direction parallel to the reflecting surface, and one point that is supported in the direction perpendicular to the reflecting surface is near one end in the longitudinal direction. The other point that is supported in the direction perpendicular to the longitudinal direction is arranged in the vicinity of the other end in the longitudinal direction, the other point that is supported in the direction perpendicular to the reflecting surface is arranged in the vicinity of the center in the longitudinal direction, and the one point that is supported in the direction parallel to the reflecting surface is It is not located near one end in the longitudinal direction and is located at a position different from the point perpendicular to the reflecting surface in the longitudinal direction, and the remaining one point supported in the direction parallel to the reflecting surface is near the other end in the longitudinal direction. It may be arranged at a different position in the longitudinal direction from a point that is not present and is supported at a right angle to the reflecting surface.
[0020]
Further, the long mirror is attached so as to be movable in the longitudinal direction between the restricting members arranged in the vicinity of both ends in the longitudinal direction, or is fixed between the restricting members by pressing against one of the restricting members with a spring changing force. Can be.
[0021]
Further, in the above, the support point in the direction perpendicular to the reflection surface is configured to be performed on the back surface of the long mirror, and the spring pressing portion corresponding to the support point is disposed on the front side of the reflection surface. You may make it.
[0022]
These long mirror support mechanisms of the present invention are preferably used in, for example, an image writing exposure unit of an image forming apparatus.
[0023]
In the present invention, at least one of the support points perpendicular to or parallel to the reflecting surface is arranged at a position that is not near the end of the long mirror in the longitudinal direction, so that the resonance frequency of the long mirror is increased. Thus, the vibration frequency of the vibration source can be avoided, and the damping of vibration can be accelerated by friction.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Below, the Example of the support mechanism of the long mirror of this invention is described.
[0025]
Prior to the description of the embodiments, symbols in the drawings for facilitating future description will be described. 11A and 11B are views for explaining the conventional long mirror support mechanism shown in FIG. 12, in which FIG. 11A is a view of the long mirror 1 viewed from the reflecting surface 2 side, and FIG. FIG. 11C is a view of the long mirror 1 viewed from the back surface 2 ′ side, FIG. 11C is a view of the cross section 1 of FIG. 11A on the arrow side, and FIG. 11D is a cross section 2 of FIG. FIG. As is clear from comparison between FIG. 11 and FIG. 12, the support points X1, X2, X3, Y1, and Y2 are indicated by thick straight arrows, and the tip of the arrow is the support point. Further, the spring pressing portions T1, T2, S1, S2, S3 and the like are indicated by zigzag arrows, and the tip ends of the arrows serve as spring pressing portions. Further, ● (black circle) is a view of supporting points X1, X2, X3, Y1, Y2, etc. seen vertically, ○ (white circle) is a view of spring pressing portions T1, T2, S1, S2, S3 etc. seen vertically. It is.
[0026]
FIG. 1 shows a support mechanism for the long mirror 1 according to the first embodiment of the present invention. 1A is a view of the long mirror 1 viewed from the reflecting surface 2 side, FIG. 1B is a view of the long mirror 1 viewed from the back surface 2 ′ side, and FIG. 1C is FIG. FIG. 1 (d) is a view of section 2 of FIG. 1 (a) viewed on the arrow side, and FIG. 1 (e) is a view of section 3 of FIG. 1 (a) on the arrow side. It is. The basic principle of this embodiment is that the long mirror 1 is supported by the three points X1, X2, and X3 in the direction perpendicular to the reflecting surface 2 and is supported by the two points Y1 and Y2 in the direction parallel to the reflecting surface 2, but the reflecting surface 2 At least one of the support points X1, X2, X3, Y1, and Y2 in the direction perpendicular to or parallel to the end of the long mirror 1 in the figure, the support point Y2 in the direction parallel to the reflecting surface 2 It is arranged at an intermediate position that is not near, and the resonance frequency of the long mirror 1 is increased so as to avoid the excitation frequency of the excitation source. In the present invention, hereinafter, the vicinity of the end portion in the longitudinal direction means the distance from the longitudinal end surface of the long mirror to a distance of 5% of the length in the longitudinal direction of the long mirror.
[0027]
Explaining this embodiment, the supporting point Y1 is in point contact with one end position of one side surface in the longitudinal direction in contact with the reflecting surface 2 of the long mirror 1 having a narrow width and a long length. Another support point Y2 is in point contact with a position closer to the center from the end, and the spring pressing portions T1 and T2 spring-press the positions corresponding to the support points Y1 and Y2 on the side surface opposite the support points Y1 and Y2, respectively. One end of the long mirror 1 is positioned and supported in parallel to the reflecting surface 2 between the support point Y1 and the spring pressing portion T1, and the long mirror 1 is positioned between the support point Y2 and the spring pressing portion T2. It is positioned and supported in parallel to the reflecting surface 2 at a position closer to the center from the other end.
[0028]
Further, the supporting points X1 and X2 are in point contact with the reflecting surface 2 of the long mirror 1 in the vicinity of both sides in the short side direction of the end position where the supporting point Y1 in the longitudinal direction is located. The support point X3 is in point contact at approximately the center in the short side direction of the end position, and positions corresponding to the support points X1, X2, and X3 on the back surface 2 ′ opposite to the reflection surface 2 of the long mirror 1 are set. The spring pressing portions S1, S2, and S3 are spring-pressed, respectively, and one end of the long mirror 1 is reflected between the supporting point X1 and the spring pressing portion S1 and between the supporting point X2 and the spring pressing portion S2. The other end of the long mirror 1 is positioned and supported on the reflecting surface 2 in the direction perpendicular to the support point X3 and the spring pressing portion S3.
[0029]
With such a configuration, there is an effect that the resonance frequency of the long mirror 1 can be increased and the attenuation of vibration can be accelerated by friction or the like.
[0030]
FIG. 2 shows a support mechanism for the long mirror 1 according to the second embodiment of the present invention. 2A is a view of the long mirror 1 viewed from the reflecting surface 2 side, FIG. 2B is a view of the long mirror 1 viewed from the back surface 2 ′ side, and FIG. 2C is FIG. FIG. 2D is a diagram of the cross section 1 of FIG. 2A viewed to the arrow side, and FIG. 2D is a diagram of the cross section 2 of FIG. The basic principle of this embodiment is that it is supported at three points X1, X2, and X3 in the direction perpendicular to the reflecting surface 2 of the long mirror 1, and supported at two points Y1 and Y2 in the direction parallel to the reflecting surface 2. The points X1, X2, X3, Y1, and Y2 are also arranged at any one of two intermediate positions that are not in the vicinity of the end in the longitudinal direction, and the resonance frequency of the long mirror 1 is increased to increase the excitation frequency of the excitation source. Is to avoid.
[0031]
Explaining this embodiment, the support point Y1 is in point contact at a distance a1 closer to the center from one end of one side surface in the longitudinal direction contacting the reflection surface 2 of the long mirror 1 having a narrow width and a long length. Further, another support point Y2 is in point contact with the center a distance a2 from the other end of the same side surface, and the positions corresponding to the support points Y1 and Y2 on the side surface opposite to the support points Y1 and Y2 are respectively set. The spring pressing portions T1 and T2 are spring-pressing, and are positioned and supported in parallel to the reflecting surface 2 at a position closer to the center from one end of the long mirror 1 between the support point Y1 and the spring pressing portion T1. Between the point Y2 and the spring pressing portion T2, the positioning is supported in the parallel direction to the reflecting surface 2 on the side closer to the center from the other end of the long mirror 1.
[0032]
Further, the supporting points X1 and X2 are in point contact with the reflecting surface 2 of the long mirror 1 near both sides in the short side direction at a distance a1 closer to the center from one end where the supporting point Y1 in the longitudinal direction is located. Further, the support point X3 is in point contact in the vicinity of one side (side on the support point Y2 side) in the short side direction at a distance a2 closer to the center from the opposite end, and the reflecting surface 2 of the long mirror 1 The spring pressing portions S1, S2, and S3 are spring-pressing the positions corresponding to the supporting points X1, X2, and X3 of the back surface 2 ′ on the opposite side, respectively, between the supporting point X1 and the spring pressing portion S1, and Between the support point X2 and the spring pressing part S2, the positioning is supported in a direction perpendicular to the reflecting surface 2 at a position closer to the center from one end of the long mirror 1, and the long mirror between the support point X3 and the spring pressing part S3. Positioned and supported in a direction perpendicular to the reflecting surface 2 on the side closer to the center from the other end of 1 .
[0033]
In this configuration, the long mirror 1 is rectangular, the length in the longitudinal direction is L, L = 180 mm, the width in the short side direction is 10 mm, the thickness of the long mirror 1 is 5 mm, and the base material of the long mirror 1 is Young. Rate 63.7 GPa, density 2.5 × 10 ^Three kg / m ^Three FIG. 4 shows the relationship between a / L and the resonance frequency (Hz) of the long mirror 1 when the Poisson ratio is 0.23 and a1 = a2 = a.
[0034]
FIG. 4 shows that there is a resonance frequency peak in the vicinity of a / L = 0.22. And from this figure, at least,
0.18 ≦ a / L ≦ 0.26 (1)
It can be seen that satisfying the above is desirable in order to avoid the excitation frequency of the excitation source.
[0035]
With such a configuration, there is an effect that the reflection surface position accuracy can be kept high without increasing the flatness of the long mirror 1 while increasing the resonance frequency of the long mirror 1.
[0036]
FIG. 3 shows a support mechanism for the long mirror 1 according to the third embodiment of the present invention. 3A is a view of the long mirror 1 viewed from the reflecting surface 2 side, FIG. 3B is a view of the long mirror 1 viewed from the back surface 2 ′ side, and FIG. 3C is FIG. FIG. 3 (d) is a view of section 2 of (a) as viewed from the arrow side, and FIG. 3 (e) is a view of section 3 of (a) as viewed from the arrow side. FIG. 3F is a view of the cross section 4 of FIG. The basic principle of this embodiment is that the long mirror 1 is supported by the three points X1, X2, and X3 in the direction perpendicular to the reflecting surface 2 and is supported by the two points Y1 and Y2 in the direction parallel to the reflecting surface 2, but the reflecting surface 2 The support points X1, X2 and X3 in the direction perpendicular to the longitudinal direction of the long mirror 1 are arranged in the vicinity of both ends in the longitudinal direction, while the support points Y1 and Y2 in the direction parallel to the reflecting surface 2 are in the vicinity of the longitudinal end of the long mirror 1 It is arranged at any one of two intermediate positions, so that the resonance frequency of the long mirror 1 is further increased to avoid the excitation frequency of the excitation source.
[0037]
Explaining this embodiment, support points X1 and X2 are in point contact with the reflecting surface 2 of the long mirror 1 near both sides in the short side direction near one end in the longitudinal direction. The support point X3 is in point contact at the approximate center in the short side direction near the end, and the positions corresponding to the support points X1, X2, and X3 of the back surface 2 ′ opposite to the reflection surface 2 of the long mirror 1 are respectively set. The spring pressing portions S1, S2, and S3 are spring pressing, and one end of the long mirror 1 is formed on the reflecting surface 2 between the support point X1 and the spring pressing portion S1 and between the support point X2 and the spring pressing portion S2. The other end of the long mirror 1 is positioned and supported on the reflecting surface 2 in the direction perpendicular to the support point X3 and the spring pressing portion S3.
[0038]
The distance between the support points X1 and X2 in the longitudinal direction of the long mirror 1 and the position of the support point X3 is L ′.
[0039]
Further, the support point Y1 is in point contact with a position a1 ′ closer to the center from the position of the support points X1 and X2 on one side surface in the longitudinal direction in contact with the reflection surface 2 of the long mirror 1, and the same side surface. Another support point Y2 is in point contact with the position a2 ′ closer to the center from the position of the support point X3, and the positions corresponding to the support points Y1 and Y2 on the side surface opposite to the support points Y1 and Y2 are respectively springs. The pressing portions T1 and T2 are spring-pressed, and are positioned and supported in a direction parallel to the reflecting surface 2 at a position closer to the center from one end of the long mirror 1 between the support point Y1 and the spring pressing portion T1. Between Y2 and the spring pressing part T2, it is positioned and supported in parallel to the reflecting surface 2 on the position side closer to the center from the other end of the long mirror 1.
[0040]
In this configuration, the long mirror 1 is rectangular, L ′ = 180 mm, the width in the short side direction is 10 mm, the thickness of the long mirror 1 is 5 mm, the Young's modulus of the base material of the long mirror 1 is 63.7 GPa, and the density is 2.5. × 10 ^Three kg / m ^Three When the Poisson's ratio is 0.23 and a1 ′ = a2 ′ = a ′, the relationship between a ′ / L ′ and the resonance frequency (Hz) of the long mirror 1 is obtained as shown in FIG. .
[0041]
FIG. 5 shows that there is a resonance frequency peak in the vicinity of a ′ / L ′ = 0.33. And from this figure, at least,
0.29 ≦ a ′ / L ′ ≦ 0.4 (2)
It can be seen that satisfying the above is desirable in order to avoid the excitation frequency of the excitation source.
[0042]
With such a configuration, by arranging the support point of the reflection surface 2 at the end of the mirror, the reflection surface 2 can be easily received without blocking the reflection surface with a support member for supporting the long mirror 1. In addition, the resonance frequency can be increased or the attenuation can be accelerated by friction or the like.
[0043]
In any of the above embodiments, the spring pressing portions S1, S2, S3, T1, and T2 are provided at corresponding positions facing the corresponding support points X1, X2, X3, Y1, and Y2. However, in the support mechanism for the long mirror 1 according to the fourth embodiment of the present invention shown in FIG. 6, the spring pressing portions T1 corresponding to the support points Y1 and Y2 that are positioned and supported in parallel to the reflecting surface 2, T2 is not provided at the corresponding facing position, but is provided at the positions of the spring pressing portions S1, S2, and S3 in the vicinity of the end portion in the longitudinal direction.
[0044]
FIG. 6 (a) showing this embodiment is a view of the long mirror 1 as seen from the reflecting surface 2 side, FIG. 6 (b) is a view of the long mirror 1 as seen from the back surface 2 ′ side, and FIG. ) Is a view of cross section 1 of (a) as viewed from the arrow side, FIG. 6 (d) is a view of cross section 2 of (a) as viewed from the arrow side, and FIG. 6 (e) is an arrow of cross section 3 of (a). FIG. 6F is a view of the cross section 4 of FIG. The positions of the support points X1, X2, X3, Y1, and Y2 in this embodiment are the same as in the embodiment of FIG. 3, and the spring pressing portions S1, S2, and S3 are also the same as in the embodiment of FIG. The spring pressing portions T1 and T2 corresponding to the support points Y1 and Y2 are the supporting points Y1 and Y2 at the same positions as the spring pressing portions S1 and S2 and the spring pressing portion S3 in the vicinity of both ends in the longitudinal direction of the long mirror 1, respectively. The end of the long mirror 1 is positioned and supported in parallel with the reflecting surface 2 between the supporting point Y1 and the spring pressing portion T1 at the end shifted by a1 ′ from the supporting point Y1. The other end of the long mirror 1 is positioned and supported in a direction parallel to the reflecting surface 2 between the support point Y2 and the spring pressing part T2 at the end shifted by a1 ′ from the support point Y2.
[0045]
In this embodiment, since the spring pressing portions S1, S2, S3, T1, and T2 can be arranged at both ends in the longitudinal direction of the long mirror 1, spring pressing members in the direction perpendicular to the perpendicular direction are provided on the reflecting surface 2 at each end. There is an advantage that the number of parts can be reduced.
[0046]
Also in this embodiment, the relationship between a ′ / L ′ and the resonance frequency (Hz) of the long mirror 1 is the same as in FIG. 5, and there is a resonance frequency peak in the vicinity of a ′ / L ′ = 0.33. . It is desirable to satisfy Equation (2) in order to avoid the excitation frequency of the excitation source.
[0047]
With such a configuration, the support point of the reflection surface 2 is arranged at the end of the mirror, so that the reflection surface 2 can be easily received without blocking the reflection surface with a support member for supporting the long mirror 1. There is an effect that the long mirror 1 can be supported and the resonance frequency can be increased without impairing the degree.
[0048]
FIG. 7 shows a support mechanism for the long mirror 1 according to the fifth embodiment of the present invention. 7A is a view of the long mirror 1 viewed from the reflecting surface 2 side, FIG. 7B is a view of the long mirror 1 viewed from the back surface 2 ′ side, and FIG. 7C is FIG. FIG. 7 (d) shows the cross section 2 of FIG. 7 (a), and FIG. 7 (e) shows the cross section 4 of FIG. 7 (a). It is the figure seen to the arrow side. The basic principle of this embodiment is that the long mirror 1 is supported by the three points X1, X2, and X3 in the direction perpendicular to the reflecting surface 2 and is supported by the two points Y1 and Y2 in the direction parallel to the reflecting surface 2, but the reflecting surface 2 The support points X1 and X3 perpendicular to the long mirror 1 are arranged in the vicinity of both ends in the longitudinal direction of the long mirror 1, the support point X2 perpendicular to the reflective surface 2 is arranged near the center of the long mirror 1 in the longitudinal direction, and the reflective surface 2 The support points Y1 and Y2 in the direction parallel to the long mirror 1 are arranged at two intermediate positions that are not in the vicinity of the end in the longitudinal direction of the long mirror 1, and the long mirrors of all the support points X1, X2, X3, Y1, and Y2 The longitudinal position of 1 is different and supported at five positions, and the resonance frequency of the long mirror 1 is further increased to avoid the excitation frequency of the excitation source.
[0049]
Explaining this embodiment, the support point Y1 is in point contact at a position about ¼ from one end of one side surface in the longitudinal direction in contact with the reflecting surface 2 of the long mirror 1 having a narrow width and a long length. Further, the support point Y2 is in point contact with a position about 1/4 from the other end of the same side surface, and the positions corresponding to the support points Y1 and Y2 on the side surface opposite to the support points Y1 and Y2 are respectively set to the spring pressing portions T1. And T2 are spring-pressed, and are positioned and supported in a direction parallel to the reflecting surface 2 at a position closer to the center from one end of the long mirror 1 between the support point Y1 and the spring-pressing portion T1, and the support point Y2 and the spring Between the pressing portions T2, the positioning is supported in parallel with the reflecting surface 2 on the side closer to the center from the other end of the long mirror 1.
[0050]
Further, the support surface X1 is in point contact with the reflecting surface 2 of the long mirror 1 near one side in the short side direction near one end in the longitudinal direction, and the support point X3 is near one side in the short side direction near the other end. The contact point X2 is in point contact, and the support point X2 is in point contact in the vicinity of the other side in the short side direction, which is approximately the center in the longitudinal direction, and the support point X1 of the back surface 2 ′ opposite to the reflection surface 2 of the long mirror 1 , X2 and X3 are respectively pressed by spring pressing portions S1, S2 and S3, between the support point X1 and the spring pressing portion S1, between the support point X2 and the spring pressing portion S2, and supported. Between the point X3 and the spring pressing portion S3, the long mirror 1 is positioned and supported in a direction perpendicular to the reflecting surface 2 at one end, the center, and the other end of the long mirror 1, respectively.
[0051]
With such a configuration, there is an effect that the resonance frequency can be increased most.
[0052]
In the support mechanism for the long mirror 1 as described above according to the present invention, the fixing method or mounting method of the long mirror 1 at both ends in the longitudinal direction of the long mirror 1 has not been described. The example of the fixing method or the attachment method will be described with reference to the same diagram of the support mechanism of the conventional long mirror 1 as in FIG. FIG. 8A is a perspective view showing the whole of the support mechanism. In this figure, based on the present invention, support points X1, X2, X3 and reflection points perpendicular to the reflection surface 2 of the long mirror 1 are shown. Although any one of the support points Y1 and Y2 in the direction parallel to the surface 2 is not arranged at a position that is not in the vicinity of the longitudinal end of the long mirror, at least one point among them is based on the present invention. Is arranged at a position that is not in the vicinity of the end of the long mirror 1 in the longitudinal direction.
[0053]
In such a configuration, in order to fix the long mirror 1 in the longitudinal direction, the expandable spring 35 and the long mirror 1 are interposed between the restricting members 31 and 33 as shown in FIG. What is necessary is just to fix so that the elongate mirror 1 may be pressed to the one limitation member 31 in the longitudinal direction by the changing force of the expandable spring 35 so as not to move. Alternatively, as shown in FIG. 8C, the reflecting surface 2 may be supported by the support points X1, X2, and X3 even if it is freely dropped between the limiting members 32 and 34 and attached to be movable in the longitudinal direction to some extent. There is no problem because the surface accuracy is maintained. 8B and 8C are views of the long mirror 1 viewed in the direction of the thick arrow in FIG.
[0054]
In the above description, the support points X1, X2, and X3 perpendicular to the reflecting surface 2 of the long mirror 1 are brought into contact with the front surface of the reflecting surface 2 and are surfaced by three-point support. The points X1, X2, and X3 are brought into contact with the back surface 2 ′ of the long mirror 1, and the spring pressing portions corresponding to these support points X1, X2, and X3 are brought into contact with the front surface of the reflecting surface 2, and the spring pressing portion. Accordingly, the spring may be pressed in a direction perpendicular to the reflecting surface 2. An example is shown in the perspective view of FIG. In this arrangement, the long mirror 1 on the substrate 5 is supported in parallel to the reflecting surface 2 by support points Y1 and Y2 arranged at two positions closer to the center from both ends, and the support points Y1 and Y2 are supported. The spring pressing portions T1 and T2 of the leaf springs 8 ′ and 9 ′ are spring-pressing at positions corresponding to the support points Y1 and Y2 on the side surface on the opposite side. The back surface 2 ′ of the long mirror 1 rests on the columns 3 and 4 standing from the substrate 5 at both end positions, and the column 3 is pointed near both sides in the width direction of the back surface 2 ′ of the long mirror 1. The support points X1 and X2 that come into contact with each other are provided, and the support 4 is provided with a support point X3 (not visible in FIG. 9) that makes point contact at the approximate center in the width direction of the back surface 2 ′ of the long mirror 1. And the spring pressing part S12 (refer FIG.12 (d)) of the leaf | plate spring 8 is spring-pressing one position corresponding to the support points X1 and X2 of the reflective surface 2 of the elongate mirror 1, and reflection surface The spring pressing portion S3 of the leaf spring 9 is pressed against the position corresponding to the second support point X3. The plate springs 8 and 8 'are attached to the support column 3, and the plate springs 9 and 9' are attached to the support column 4 at one end, and the spring pressing portion S12 is supported by the support points X1 and X2 and the spring pressing portion. S3 presses against the support point X3. Therefore, the leaf springs 8 and 9 are formed in a shape that holds the long mirror 1 from the back surface 2 'side.
[0055]
Next, specific configurations of the support points X1, X2, X3, Y1, Y2, etc., and the spring pressing portions S1, S2, S3, S12, T1, T2, etc. will be exemplified. The support points X1, X2, X3 etc. that come into contact with the reflective surface 2 and the back surface 2 ′ are composed of support points that are in point contact with the support columns 3 and 4 that stand from the substrate 5, as shown in FIGS. Alternatively, as shown in the cross section of FIG. 10, the support point X2 on the substrate 5 side consists of a support point directly provided on the substrate 5, and the support point X1 on the side away from the substrate 5 is the long mirror 1 It is good also considering the front-end | tip of the supporting member 36 attached to the support | pillar 3 head of the back surface 2 side so that it may hold from the back surface 2 'side. Further, the spring pressing portions S1, S2, S3, S12, T1, T2, etc. are partly plate springs as shown in FIGS. 8, 9, and 12 as shown in FIGS. However, as shown in FIG. 10, all of them can be configured by an expandable spring (spiral spring).
[0056]
The long mirror support mechanism of the present invention has been described above based on the embodiments. However, the present invention is not limited to these, and various modifications are possible. The long mirror support mechanism of the present invention is not limited to the image writing exposure unit of an image forming apparatus such as a laser beam printer illustrated in FIG. It can be applied to the support mechanism.
[0057]
【The invention's effect】
As is apparent from the above description, according to the long mirror support mechanism of the present invention, at least one of the support points perpendicular or parallel to the reflecting surface is not near the longitudinal end of the long mirror. Since it is disposed at a position, the resonance frequency of the long mirror can be increased to avoid the excitation frequency of the excitation source, and vibration attenuation can be accelerated by friction or the like.
[Brief description of the drawings]
FIG. 1 is a view showing a long mirror support mechanism according to a first embodiment of the present invention.
FIG. 2 is a view showing a long mirror support mechanism according to a second embodiment of the present invention.
FIG. 3 is a view showing a long mirror support mechanism according to a third embodiment of the present invention.
FIG. 4 is a diagram showing resonance frequency characteristics of the second embodiment.
FIG. 5 is a diagram showing resonance frequency characteristics of the third embodiment.
FIG. 6 is a view showing a long mirror support mechanism according to a fourth embodiment of the present invention.
FIG. 7 is a view showing a long mirror support mechanism according to a fifth embodiment of the present invention.
FIG. 8 is a view for explaining an example of a method of fixing and attaching a long mirror in the longitudinal direction in the long mirror support mechanism of the present invention.
FIG. 9 is a perspective view showing a modification of the long mirror support mechanism of the present invention.
FIG. 10 is a diagram for illustrating the configuration of a support point and a spring pressing portion in the present invention.
FIG. 11 is a diagram for explaining symbols used for describing an embodiment of the present invention based on FIG. 12;
FIG. 12 is a diagram for explaining an example of a conventional long mirror support mechanism;
FIG. 13 is a diagram for explaining a configuration example of an image writing exposure unit of an image forming apparatus to which the long mirror support mechanism of the present invention can be applied.
[Explanation of symbols]
1 ... long mirror
2. Front of long mirror (reflective surface)
2 '... Back of long mirror
3, 4, 6, 7 ... struts
5 ... Board
8, 9, 8 ', 9' ... leaf spring
10 ... Rotating polygon mirror
11 ... Deflecting mirror
12 ... Rotating shaft
20. Scanning optical system
21, 22, 23 ... Folding mirror
25 ... surface to be scanned
31, 32, 33, 34 ... limiting member
35 ... Expandable spring
36 ... Support member
a ₁ , A ₂ ... light beam
X1, X2, X3, Y1, Y2 ... support points
S1, S2, S3, S12 ... Expandable spring (spring pressing part)
T1, T2 ... Spring pressing part

Claims

A support mechanism for a long mirror having a narrow width and a long length, which is supported by three support points in a direction perpendicular to the reflection surface and supported by two support points in a direction parallel to the reflection surface. In the support mechanism,
Two points that are supported in a direction perpendicular to the reflecting surface are arranged in the vicinity of one end in the longitudinal direction, and the remaining one point that is supported in a direction perpendicular to the reflecting surface is arranged in the vicinity of the other end in the longitudinal direction. The point is disposed at a position that is not near one end in the longitudinal direction, and the remaining one point that is supported in a direction parallel to the reflecting surface is disposed at a position that is not near the other end in the longitudinal direction.
In the longitudinal direction of the long mirror between the arrangement position of two points that are perpendicularly supported by the reflection surface near one end in the longitudinal direction and the other one arrangement position that is supported in the direction perpendicular to the reflection surface near the other end in the longitudinal direction The distance in the longitudinal direction of the long mirror between the arrangement position of two points that are supported at right angles to the reflection surface near one end in the longitudinal direction and the arrangement position of one point that is supported in a direction parallel to the reflection surface is defined as L ′. a ′, in the longitudinal direction of the long mirror between the arrangement position of the remaining one point supported in the direction perpendicular to the reflection surface near the other end in the longitudinal direction and the arrangement position of the remaining one point supported in the direction parallel to the reflection surface When the distance is a ′,
0.29 ≦ a ′ / L ′ ≦ 0.4 (2)
A long mirror support mechanism characterized by satisfying

A spring pressing portion arranged on the opposite side of the two support points opposed to elongated mirror respectively supporting the direction parallel to the reflecting surface, the length according to claim 1, characterized in that arranged near opposite longitudinal ends Shaft mirror support mechanism.

A spring pressing portion disposed on the opposite side of the long mirror so as to face each of the two support points supported in the direction perpendicular to the reflection surface near one end in the longitudinal direction, and one support point supported in a direction parallel to the reflection surface The remaining one supporting point which is integrated with a spring pressing portion disposed on the opposite side of the long mirror and in the vicinity of one end in the longitudinal direction so as to be opposed to the reflecting surface near the other end in the longitudinal direction. A spring pressing portion disposed on the opposite side of the long mirror opposite to the long mirror, and the other end in the longitudinal direction opposite to the long mirror opposite to the remaining one supporting point supported in parallel to the reflecting surface 3. The support mechanism for a long mirror according to claim 2, wherein a spring pressing portion disposed in the vicinity is integrated.

The long mirror support mechanism according to any one of claims 1 to 3 , wherein the long mirror is attached so as to be movable in a longitudinal direction between restricting members disposed in the vicinity of both ends in the longitudinal direction.

The long mirror according to any one of claims 1 to 3 , wherein the long mirror is fixed by being pressed against one of the limiting members by a spring changing force between the limiting members disposed in the vicinity of both ends in the longitudinal direction. Shaft mirror support mechanism.

The support point perpendicular to the reflection surface is configured to be performed on the back surface of the long mirror, and the spring pressing portion corresponding to the support point is disposed on the front side of the reflection surface. The long mirror support mechanism according to any one of claims 1 to 5 , wherein:

An image forming apparatus featured by use of the image writing exposure unit support mechanism of the long mirror of any one of claims 1 6.