JPH1164759A - Light scanning optical device - Google Patents

Light scanning optical device

Info

Publication number
JPH1164759A
JPH1164759A JP9243426A JP24342697A JPH1164759A JP H1164759 A JPH1164759 A JP H1164759A JP 9243426 A JP9243426 A JP 9243426A JP 24342697 A JP24342697 A JP 24342697A JP H1164759 A JPH1164759 A JP H1164759A
Authority
JP
Japan
Prior art keywords
light beam
optical
deflecting
scanning
light
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP9243426A
Other languages
Japanese (ja)
Inventor
Koji Toyoda
浩司 豊田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Canon Inc
Original Assignee
Canon Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Canon Inc filed Critical Canon Inc
Priority to JP9243426A priority Critical patent/JPH1164759A/en
Publication of JPH1164759A publication Critical patent/JPH1164759A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To reduce the fluctuation of light quantity within one line on the surface to be scanned by providing luminous flux dividing means in an optical path so that the incident direction of luminous flux at a center scanning to the deflection plane of a deflection means is almost matched with the normal direction of the deflection plane when the luminous flux is projected to a main scanning cross section. SOLUTION: A cylindrical lens 2 has a prescribed refractive power only in a subscanning cross section to roughly form a luminous flux passing through an aperture 1c on the deflection plane 4a of an optical deflector 4 as a line image in the subscanning cross section. In this case, the width of the luminous flux emitted from the lens 2 is formed so as to become wider than that of a deflection plane 4a. Moreover, the luminous flux dividing means are constituted so that the incident direction of the luminous flux at a center scanning to the deflection plane 4a is almost matched with the normal direction of the deflection plane 4a when the incident luminous flux is projected to the main scanning cross by a half mirror 3. Thus, the amount of change in the width of the luminous flux to be generated in accordance with the revolution of the optical deflector 4 can be suppressed small.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は光走査光学装置に関
し、特に光源手段から光変調され射出した光束を回転多
面鏡より成る光偏向器で偏向反射させた後、fθ特性を
有する走査光学手段(fθレンズ)を介して被走査面上
を光走査して画像情報を記録するようにした、例えば電
子写真プロセスを有するレーザービームプリンタやデジ
タル複写機等の装置に好適な光走査光学装置に関するも
のである。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device, and more particularly to a scanning optical device having an f.theta. Characteristic after deflecting and reflecting a light beam emitted from a light source means after being modulated by an optical deflector comprising a rotary polygon mirror. The present invention relates to an optical scanning optical device suitable for an apparatus such as a laser beam printer or a digital copying machine having an electrophotographic process, in which image information is recorded by optically scanning the surface to be scanned via an fθ lens). is there.

【0002】[0002]

【従来の技術】従来よりレーザービームプリンタ(LB
P)等の光走査光学装置においては画像信号に応じて光
源手段から光変調され射出した光束を、例えば回転多面
鏡(ポリゴンミラー)より成る光偏向器により周期的に
偏向させ、fθ特性を有する走査光学手段(fθレン
ズ)によって感光性の記録媒体(感光ドラム)面上にス
ポット状に収束させ、その面上を光走査して画像記録を
行なっている。
2. Description of the Related Art Conventionally, a laser beam printer (LB) has been used.
In an optical scanning optical device such as P), a light beam emitted from a light source unit after being light-modulated in accordance with an image signal is periodically deflected by an optical deflector composed of, for example, a rotating polygon mirror (polygon mirror) to have fθ characteristics. The light is converged in the form of a spot on a photosensitive recording medium (photosensitive drum) surface by scanning optical means (fθ lens), and the surface is optically scanned to record an image.

【0003】図6は従来の光走査光学装置の要部概略図
である。同図において光源手段61から光変調され射出
した発散光束はコリメーターレンズ62により略平行光
束(もしくは発散光束、もしくは収束光束)に変換さ
れ、絞り(アパーチャー)63によって該光束(光量)
を制限して副走査断面内にのみ所定の屈折力を有する入
射光学手段としてのシリンドリカルレンズ64に入射し
ている。シリンドリカルレンズ64に入射した略平行光
束のうち主走査断面内においてはそのまま略平行光束の
状態で射出する。また副走査断面内においては集束して
回転多面鏡から成る光偏向器65の偏向面65aにほぼ
線像として結像している。そして光偏向器65の偏向面
65aで偏向反射された光束をfθ特性を有する走査光
学手段66を介して被走査面としての感光ドラム面67
上に導光し、該光偏向器65を矢印A方向に回転させる
ことによって、該感光ドラム面67上を矢印B方向(主
走査方向)に光走査して画像情報の記録を行なってい
る。
FIG. 6 is a schematic view of a main part of a conventional optical scanning optical device. In the figure, a divergent light beam that has been light-modulated and emitted from the light source means 61 is converted into a substantially parallel light beam (or a divergent light beam or a convergent light beam) by a collimator lens 62, and the light beam (light amount) is converted by a stop (aperture) 63.
And is incident on a cylindrical lens 64 as an incident optical means having a predetermined refractive power only in the sub-scan section. Of the substantially parallel light beams that have entered the cylindrical lens 64, they are emitted as they are in the state of substantially parallel light beams in the main scanning section. In the sub-scan section, the light is converged and formed as a substantially linear image on the deflecting surface 65a of the optical deflector 65 composed of a rotating polygon mirror. The light beam deflected and reflected by the deflecting surface 65a of the optical deflector 65 is passed through a scanning optical unit 66 having fθ characteristics to a photosensitive drum surface 67 as a surface to be scanned.
By guiding the light upward and rotating the optical deflector 65 in the direction of arrow A, the photosensitive drum surface 67 is optically scanned in the direction of arrow B (main scanning direction) to record image information.

【0004】上記の走査光学手段66の副走査方向の屈
折力は光偏向器65の偏向面65aと被走査面67との
間が共役結像関係になるように適切に設定されており、
これにより光偏向器の偏向面が回転軸に対して倒れてい
るときの角度誤差、即ち面倒れを補正し、走査線のピッ
チムラが生じないようになっている。
The refractive power of the scanning optical means 66 in the sub-scanning direction is appropriately set so that the deflecting surface 65a of the optical deflector 65 and the surface to be scanned 67 have a conjugate image relationship.
Thereby, the angle error when the deflection surface of the optical deflector is tilted with respect to the rotation axis, that is, the surface tilt is corrected, so that the pitch unevenness of the scanning line does not occur.

【0005】このような光走査光学装置はレーザービー
ムプリンターの高速化、高精細化によってより高速走査
の可能なものが求められているが、駆動手段であるモー
ターの回転数、偏向手段である光偏向器(回転多面鏡)
の面数や大きさ等によりその高速走査が制限されてい
る。
Such optical scanning optical devices are required to be able to perform higher-speed scanning by increasing the speed and definition of laser beam printers. However, the number of rotations of a motor as a driving means and the light as a deflecting means are required. Deflector (rotating polygon mirror)
The high-speed scanning is limited by the number and size of the surfaces.

【0006】そこで従来では偏向手段である光偏向器の
偏向面の回転方向(主走査方向)の幅よりも、該光偏向
器に入射する光束の主走査方向と対応する方向の光束幅
の方が大きく設定された、所謂オーバーフィルドタイプ
の光走査光学装置が、例えば特開平8−171069号
公報で提案されている。このようなオーバーフィルドタ
イプの光走査光学装置は高速化及び高精細化に適し、ま
た光偏向器の径の小型化を図ることができるといった特
長を有している。
Therefore, in the related art, the light beam width in the direction corresponding to the main scanning direction of the light beam incident on the light deflector is smaller than the width in the rotation direction (main scanning direction) of the deflecting surface of the light deflector, which is the deflecting means. A so-called overfilled type optical scanning optical device in which is set large is proposed, for example, in Japanese Patent Application Laid-Open No. Hei 8-17169. Such an overfilled type optical scanning optical device has features that it is suitable for high speed and high definition and that the diameter of the optical deflector can be reduced.

【0007】[0007]

【発明が解決しようとする課題】上記のオーバーフィル
ドタイプの光走査光学装置は光偏向器が回転するにつ
れ、該光偏向器の偏向面の入射光学手段(シリンドリカ
ルレンズ)に面する幅が変化する。その結果、実際の結
像に用いられる光束の光束幅も光偏向器が回転するにつ
れて変化し、被走査面である感光ドラム面上における1
ライン内での光量変動量が無視できなくなってくるとい
う問題点がある。上述した特開平8−171069号公
報では光偏向器の偏向面に対し走査偏向面内(主走査断
面内)で光束を斜入射させる構成となっている。このと
き走査中央部に対する周辺部での光量は10%以上変動
することになる。また感光ドラム面上における光量比に
は、その他レンズの透過率、ミラー反射率の角度依存性
等の多くの要因が含まれるため、さらに光量比が増大し
てしまう。光量比が増大すると出力画像での中央部と周
辺部との濃度差が生じ、この結果、良好なる画像が得ら
れなくなってくるという問題点が生じてくる。
In the above overfilled optical scanning optical device, as the optical deflector rotates, the width of the deflection surface of the optical deflector facing the incident optical means (cylindrical lens) changes. . As a result, the light beam width of the light beam used for actual image formation also changes as the optical deflector rotates, and the light beam width on the photosensitive drum surface, which is the surface to be scanned, is changed.
There is a problem that the amount of light fluctuation in the line cannot be ignored. In the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-17169, the light beam is obliquely incident on the deflection surface of the optical deflector within the scanning deflection surface (in the main scanning section). At this time, the amount of light in the peripheral portion with respect to the central portion of the scan varies by 10% or more. Further, the light amount ratio on the photosensitive drum surface includes many factors such as the transmittance of the lens and the angle dependency of the mirror reflectivity, so that the light amount ratio further increases. When the light amount ratio increases, a density difference occurs between the central portion and the peripheral portion of the output image, and as a result, a problem arises in that a good image cannot be obtained.

【0008】本発明は入射光学手段を射出した光束の光
束幅を主走査断面内において、偏向手段(光偏向器)の
偏向面の幅よりも広くなるように形成し、かつ該光束を
主走査断面に射影したときに偏向手段の偏向面への中心
走査における光束の入射方向と該偏向面の法線方向とが
略一致するように光路内に光束分割手段を設けることに
より、該偏向手段の回転に従う光束幅の変化量を小さく
抑えることができ、これにより被走査面上における1ラ
イン内での光量変動量を小さく抑えることができる光走
査光学装置の提供を目的とする。
According to the present invention, the width of the light beam emitted from the incident optical means is formed to be wider than the width of the deflecting surface of the deflecting means (optical deflector) in the main scanning section, and the light beam is scanned in the main scanning direction. By providing the light beam splitting means in the optical path such that the direction of incidence of the light beam in the center scan on the deflection surface of the deflection means when projected onto the cross section substantially coincides with the normal direction of the deflection surface, It is an object of the present invention to provide an optical scanning optical apparatus capable of suppressing a change amount of a light beam width according to the rotation, thereby suppressing a light amount fluctuation amount within one line on a surface to be scanned.

【0009】[0009]

【課題を解決するための手段】本発明の光走査光学装置
は、(1) 光源手段から射出された光束の状態を変換光学
素子により他の状態に変換し、該変換された光束の光束
断面形状をアパーチャーにより整形し、入射光学手段で
集光して光束分割手段を介して偏向手段の偏向面上にお
いて主走査方向に長手の線状に結像させ、該偏向手段で
偏向反射された光束を該光束分割手段を介して走査光学
手段により被走査面上にスポット状に結像させ、該被走
査面上を光走査する光走査光学装置において、該光源手
段の中心、該変換光学素子の光軸、該アパーチャーの中
心、そして該入射光学手段の光軸は、主走査断面に対し
て垂直な面内で、かつ全走査角の中心軸上に位置するよ
うに配置され、該入射光学手段を介した光束の光束幅は
主走査断面内において、該偏向手段の偏向面の幅より広
くなるように形成され、かつ該光束を主走査断面に射影
したときに該偏向手段の偏向面への中心走査における光
束の入射方向と該偏向面の法線方向とが略一致するよう
に光路内に該光束分割手段が設けられていることを特徴
としている。
The light scanning optical device according to the present invention comprises: (1) converting the state of a light beam emitted from a light source means into another state by a conversion optical element, and obtaining a light beam cross section of the converted light beam; The shape is shaped by an aperture, condensed by the incident optical means, focused on the deflecting surface of the deflecting means via the light beam splitting means to form an image in the form of a long line in the main scanning direction, and the light flux deflected and reflected by the deflecting means In the form of a spot on the surface to be scanned by the scanning optical means via the light beam dividing means, and optically scans the surface to be scanned, wherein the center of the light source means, the center of the conversion optical element The optical axis, the center of the aperture, and the optical axis of the incident optical means are arranged in a plane perpendicular to the main scanning section and on the central axis of the full scanning angle; The beam width of the beam passing through is within the main scanning section. When the light beam is projected onto the main scanning section, the incident direction of the light beam in the center scan on the deflection surface of the deflecting means and the width of the deflecting surface The light beam splitting means is provided in the optical path so that the normal direction substantially coincides with the normal direction.

【0010】特に(1-1) 前記光束分割手段は前記入射光
学手段を介した光束を前記偏向手段側に反射させ、かつ
該偏向手段で偏向反射された光束を透過させて前記走査
光学手段に入射させることや、(1-2) 前記偏向手段の偏
向面で偏向反射された光束のうち前記光束分割手段で前
記光源手段側へ反射される光束が、前記アパーチャーで
半分以上ケラレるように副走査断面内における該光束分
割手段の該偏向面の法線に対する傾斜角度を設定したこ
とや、(1-3) 前記光束分割手段はハーフミラーより成る
ことや、(1-4) 前記ハーフミラーのミラー面は平面より
成ることや、(1-5) 前記ハーフミラーのミラー面は曲面
より成ることや、(1-6) 前記変換光学素子は前記光源手
段から射出した光束の状態を略平行光束、もしくは収束
光束、もしくは発散光束に変換していることや、(1-7)
前記偏向手段に入射する光束は副走査断面内において該
偏向手段の偏向面に対し斜め方向から入射すること、等
を特徴としている。
In particular, (1-1) the light beam splitting means reflects the light beam passing through the incident optical means toward the deflecting means, and transmits the light beam deflected and reflected by the deflecting means to the scanning optical means. (1-2) Of the light beams deflected and reflected by the deflecting surface of the deflecting device, (1-2) a sub-light beam reflected by the light beam splitting device toward the light source unit is more than half vignetted by the aperture. The inclination angle of the light beam splitting means with respect to the normal of the deflecting surface in the scanning section is set, (1-3) the light beam splitting means is formed of a half mirror, and (1-4) the half mirror is The mirror surface may be a flat surface, (1-5) the mirror surface of the half mirror may be a curved surface, or (1-6) the conversion optical element may convert the state of the light beam emitted from the light source means into a substantially parallel light beam. Or converted to a convergent or divergent beam And that and that, (1-7)
The light beam incident on the deflecting means is obliquely incident on the deflecting surface of the deflecting means in the sub-scan section.

【0011】[0011]

【発明の実施の形態】図1は本発明の実施形態1の要部
概略図、図2は本発明の実施形態1の副走査方向の主要
部分の要部断面図(副走査断面図)、図3は本発明の実
施形態1の主走査方向の主要部分の要部断面図(主走査
断面図)である。
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a first embodiment of the present invention, FIG. 2 is a cross-sectional view of a main part (sub-scan cross-sectional view) of a main part in a sub-scanning direction of the first embodiment of the present invention, FIG. 3 is a cross-sectional view (main scanning cross-sectional view) of a main part of a main part in the main scanning direction according to the first embodiment of the present invention.

【0012】図中、1aは光源手段であり、例えば半導
体レーザーより成っている。1bは変換光学素子であ
り、例えば光源手段1aから射出された光束(光ビー
ム)を発散光束(もしくは収束光束、もしくは略平行光
束)に変換している。1cはアパーチャ(絞り)であ
り、光束の光束断面形状を整形している。尚、半導体レ
ーザー1a、変換光学素子b、そしてアパーチャ1c等
の各要素は光源ユニット1の一要素を構成している。
In FIG. 1, reference numeral 1a denotes light source means, which is made of, for example, a semiconductor laser. A conversion optical element 1b converts, for example, a light beam (light beam) emitted from the light source 1a into a divergent light beam (or a convergent light beam or a substantially parallel light beam). Reference numeral 1c denotes an aperture (aperture) for shaping the light beam cross section. Each element such as the semiconductor laser 1a, the conversion optical element b, and the aperture 1c constitutes one element of the light source unit 1.

【0013】2は入射光学手段としてのシリンドリカル
レンズであり、副走査断面内にのみ所定の屈折力を有し
ており、アパーチャ1cを通過した光束を副走査断面内
で後述する偏向手段としての光偏向器(回転多面鏡)4
の偏向面(反射面)4aにほぼ線像(主走査方向に長手
の線像)として結像させている。本実施形態ではこのシ
リンドリカルレンズ2を射出した光束の光束幅を主走査
断面内において、光偏向器4の偏向面の幅より広くなる
ように形成している。
Reference numeral 2 denotes a cylindrical lens as incident optical means, which has a predetermined refractive power only in the sub-scanning section, and converts a light beam passing through the aperture 1c into a light as a deflecting means which will be described later in the sub-scanning section. Deflector (rotating polygon mirror) 4
Are formed as substantially linear images (linear images elongated in the main scanning direction) on the deflecting surface (reflective surface) 4a. In the present embodiment, the light beam width of the light beam emitted from the cylindrical lens 2 is formed to be wider than the width of the deflection surface of the light deflector 4 in the main scanning section.

【0014】また光源手段1aの中心、変換光学素子1
bの光軸、アパーチャー1cの中心、そしてシリンドリ
カルレンズ2の光軸は、主走査断面に対して垂直な面内
で、かつ全走査角の中心軸上に位置するように配置され
ている。
The center of the light source means 1a, the conversion optical element 1
The optical axis b, the center of the aperture 1c, and the optical axis of the cylindrical lens 2 are arranged in a plane perpendicular to the main scanning section and on the central axis of the full scanning angle.

【0015】3は光束分割手段としてのハーフミラーで
あり、ミラー面を平面より形成しており、副走査断面内
において光偏向器4の偏向面4aの法線Lに対し45.
5°傾けて配している。このハーフミラー3はシリンド
リカルレンズ2を射出した光束を光偏向器4の偏向面4
a側に反射させ、かつ該偏向面4aで偏向反射された光
束を透過させて後述する走査光学手段としてのfθレン
ズ5に入射させている。このとき主走査断面内において
は入射光束を主走査断面に射影したときに光偏向器4の
偏向面4aへの中心走査における光束の入射方向と該偏
向面4aの法線L方向とが略一致するように該光束を光
偏向器4に入射させており、副走査断面内においては該
偏向面4aの法線Lに対して1°の角度で該光束を光偏
向器4に斜入射させている。
Numeral 3 denotes a half mirror as a light beam splitting means, which has a mirror surface formed of a flat surface, and which is located at 45.degree. With respect to the normal L of the deflecting surface 4a of the optical deflector 4 in the sub-scanning section.
It is arranged at an angle of 5 °. The half mirror 3 converts the light beam emitted from the cylindrical lens 2 into a deflecting surface 4 of an optical deflector 4.
The light flux reflected on the a side and deflected and reflected by the deflecting surface 4a is transmitted and made incident on an fθ lens 5 as scanning optical means described later. At this time, in the main scanning section, when the incident light beam is projected onto the main scanning section, the incident direction of the light beam in the center scanning on the deflecting surface 4a of the optical deflector 4 substantially coincides with the normal L direction of the deflecting surface 4a. The light beam is incident on the light deflector 4 so that the light beam is obliquely incident on the light deflector 4 at an angle of 1 ° with respect to the normal L of the deflection surface 4a in the sub-scan section. I have.

【0016】偏向手段としての光偏向器4は、例えば回
転多面鏡(ポリゴンミラー)より成っており、ポリゴン
モータ等の駆動手段(不図示)により図中矢印A方向に
一定速度で回転している。
The optical deflector 4 as a deflecting means is composed of, for example, a rotating polygon mirror (polygon mirror), and is rotated at a constant speed in a direction indicated by an arrow A in the figure by a driving means (not shown) such as a polygon motor. .

【0017】走査光学手段としてのfθレンズ5は、光
偏向器4の偏向面4aによって偏向反射された画像情報
に基づく光束を被走査面としての感光ドラム面7上に結
像させている。
The fθ lens 5 as scanning optical means forms a light beam based on image information deflected and reflected by the deflecting surface 4a of the optical deflector 4 on a photosensitive drum surface 7 as a surface to be scanned.

【0018】6は導光手段としての折り返しミラーであ
り、fθレンズ5を通した光束を感光ドラム面7側に折
り返している。
Reference numeral 6 denotes a return mirror as light guide means, which returns the light flux passing through the fθ lens 5 to the photosensitive drum surface 7 side.

【0019】本実施形態において半導体レーザー1aよ
り射出した光束は変換光学素子1bにより略平行光束と
され、アパーチャー1cによって光束の光束断面形状を
整形してシリンドリカルレンズ2に入射している。シリ
ンドリカルレンズ2に入射した略平行光束のうち主走査
断面内においてはそのまま略平行光束の状態で図3に示
すようにハーフミラー3により入射光束を主走査断面に
射影したときに光偏向器4の偏向面4aへの中心走査に
おける光束の入射方向と該偏向面4aの法線L方向とが
略一致するようにして該光偏向器4に入射し、また副走
査断面内においては収束して図2に示すように該ハーフ
ミラー3により該光偏向器4の偏向面4aの法線Lに対
して1°の角度で該光偏向器4に斜入射している。
In the present embodiment, the light beam emitted from the semiconductor laser 1a is converted into a substantially parallel light beam by the conversion optical element 1b, and the light beam cross-sectional shape of the light beam is shaped by the aperture 1c to be incident on the cylindrical lens 2. As shown in FIG. 3, when the incident light beam is projected onto the main scanning cross section by the half mirror 3 in the state of substantially parallel light beam in the main scanning cross section of the substantially parallel light beam incident on the cylindrical lens 2, the light deflector 4 The light beam enters the optical deflector 4 in such a manner that the incident direction of the light beam in the central scanning on the deflecting surface 4a substantially coincides with the direction of the normal L of the deflecting surface 4a, and converges in the sub-scan section. As shown in FIG. 2, the light is obliquely incident on the light deflector 4 by the half mirror 3 at an angle of 1 ° with respect to a normal L of the deflection surface 4a of the light deflector 4.

【0020】そして光偏向器4の偏向面4aで偏向反射
された光束はハーフミラー3を透過してfθレンズ5に
より折り返しミラー6を介して感光ドラム面7上にスポ
ット状に結像され、該光偏向器4を矢印A方向に回転さ
せることによって、該感光ドラム面7上を矢印B方向
(主走査方向)に光走査している。これにより記録媒体
としての感光ドラム面7上に画像記録を行なっている。
The light beam deflected and reflected by the deflecting surface 4a of the light deflector 4 passes through the half mirror 3 and is formed into an image on the photosensitive drum surface 7 by the fθ lens 5 via the return mirror 6 in the form of a spot. By rotating the optical deflector 4 in the direction of arrow A, the photosensitive drum surface 7 is optically scanned in the direction of arrow B (main scanning direction). Thus, an image is recorded on the photosensitive drum surface 7 as a recording medium.

【0021】上記の走査光学手段としてのfθレンズ5
の副走査方向の屈折力は光偏向器4の偏向面4aと感光
ドラム面7との間が共役結像関係になるように適切に設
定されており、これにより光偏向器4の偏向面4aが回
転軸に対して倒れているときの角度誤差、即ち面倒れを
補正し、走査線のピッチムラが生じないようになってい
る。
Fθ lens 5 as the above-mentioned scanning optical means
Is appropriately set so that the deflecting surface 4a of the optical deflector 4 and the photosensitive drum surface 7 have a conjugate imaging relationship, whereby the deflecting surface 4a of the optical deflector 4 is Is corrected with respect to the rotation axis, i.e., surface tilt, so that scanning line pitch unevenness does not occur.

【0022】本実施形態のようにハーフミラー3を光偏
向器4とfθレンズ5(及びシリンドリカルレンズ2)
との間の光路内に配した場合、例えば該光偏向器4で偏
向反射された光束のうち、該ハーフミラー3で反射され
た光束(戻り光)が光源としての半導体レーザー1aに
戻ると、該半導体レーザー1aからの出力が不安定にな
り光量変動が生じるという問題点がある。そこで本実施
形態では光偏向器4からの戻り光が半導体レーザー1a
に入射するのを防ぐため、図2に示すように該戻り光が
アパーチャー(不図示)で半分以上ケラレるように副走
査断面内におけるハーフミラー3を偏向面4aの法線L
に対する傾斜角度を上述の如く45.5°に設定してい
る。即ち、光束は偏向面4aの法線Lに対し、1°の角
度を付けて該偏向面4aに入射することになり、これに
より半導体レーザー1aの光量変動を防止することがで
きる。
As in the present embodiment, the half mirror 3 is replaced with the optical deflector 4 and the fθ lens 5 (and the cylindrical lens 2).
For example, when the light flux (return light) reflected by the half mirror 3 of the light flux deflected and reflected by the light deflector 4 returns to the semiconductor laser 1a as a light source, There is a problem that the output from the semiconductor laser 1a becomes unstable and the light quantity varies. Therefore, in this embodiment, the return light from the optical deflector 4 is the semiconductor laser 1a
In order to prevent the reflected light from entering the half mirror 3 in the sub-scanning section so that the return light is vibrated by an aperture (not shown) more than half as shown in FIG.
Is set to 45.5 ° as described above. That is, the light beam enters the deflecting surface 4a at an angle of 1 ° with respect to the normal line L of the deflecting surface 4a, whereby the light quantity fluctuation of the semiconductor laser 1a can be prevented.

【0023】本実施形態においては上述の如くシリンド
リカルレンズ2を射出した光束の光束幅が図3に示すよ
うに主走査断面内において、光偏向器4の偏向面4aの
幅よりも広くなるように形成しており、かつハーフミラ
ー3により入射光束を主走査断面に射影したときに該光
偏向器4の偏向面4aへの中心走査における光束の入射
方向と該偏向面4aの法線L方向とが略一致するように
構成している。これにより本実施形態ではオーバーフィ
ールドタイプの光走査光学装置において避けることので
きない光偏向器の回転に従う光束幅の変化量を小さく抑
え、被走査面上における1ライン内での光量変動量を小
さく抑えている。
In this embodiment, as described above, the light beam width of the light beam emitted from the cylindrical lens 2 is set to be wider than the width of the deflection surface 4a of the light deflector 4 in the main scanning section as shown in FIG. When the half mirror 3 projects the incident light beam onto the main scanning section, the incident direction of the light beam in the center scanning on the deflection surface 4a of the light deflector 4 and the normal L direction of the deflection surface 4a Are configured to substantially match. As a result, in this embodiment, the amount of change in the light beam width due to the rotation of the optical deflector, which cannot be avoided in the overfield type optical scanning optical device, is reduced, and the amount of light fluctuation within one line on the surface to be scanned is reduced. ing.

【0024】図4は光偏向器の偏向面に対する入射角に
よる光束幅の変化を示したグラフである。本実施形態で
は上述の如く主走査断面内において偏向面への中心走査
における光束の入射方向と該偏向面の法線方向とが略一
致するように構成している為、該偏向面に対する光束の
入射角は0°に対応する。同図から分かるように入射角
30°以上の場合、光束幅は1走査内において20%以
上変化するが、入射角0°では10%に抑えられる。こ
こで入射角を0〜30°にするには光偏向器とfθレン
ズとの間の光路内に入射光学系を配置するような構成と
なり、かつfθレンズの焦点距離を長く取らなければな
らなくなる。これは装置全体の大型化を招き、実用的で
ない。
FIG. 4 is a graph showing a change in light beam width depending on the incident angle with respect to the deflection surface of the optical deflector. In the present embodiment, as described above, since the incident direction of the light beam in the center scanning on the deflection surface in the main scanning cross section and the normal direction of the deflection surface substantially coincide with each other, the light beam The angle of incidence corresponds to 0 °. As can be seen from the figure, when the incident angle is 30 ° or more, the light flux width changes by 20% or more in one scan, but is suppressed to 10% at the incident angle of 0 °. Here, in order to make the incident angle 0 to 30 °, the incident optical system must be arranged in the optical path between the optical deflector and the fθ lens, and the focal length of the fθ lens must be long. . This leads to an increase in the size of the entire apparatus and is not practical.

【0025】そこで本実施形態では上述した如くハーフ
ミラー3を用いて入射光束を主走査断面に射影したとき
に該光偏向器4の偏向面4aへの中心走査における光束
の入射方向と該偏向面4aの法線L方向とが略一致する
ように構成することにより、感光ドラム面7上における
1ライン内での光量変動量を小さく抑えることができ、
これにより良好なる画像を得ている。
Therefore, in the present embodiment, when the incident light beam is projected onto the main scanning section using the half mirror 3 as described above, the incident direction of the light beam in the center scanning on the deflecting surface 4a of the light deflector 4 and the deflecting surface By configuring the normal line L of 4a to substantially coincide with the direction of the normal line L, it is possible to reduce the amount of light quantity fluctuation within one line on the photosensitive drum surface 7,
Thereby, a good image is obtained.

【0026】また光源としての半導体レーザーから射出
される光束はガウスビームであるので、例えば光束の使
用位置によっては光量が変わるが、上述したようにハー
フミラーを利用した本実施形態の手段が最も効果的であ
ることは明らかである。
Since the light beam emitted from the semiconductor laser as a light source is a Gaussian beam, the amount of light varies depending on, for example, the position where the light beam is used, but the means of the present embodiment using the half mirror as described above is most effective. Clearly,

【0027】図5は本発明の実施形態2の要部概略図で
ある。同図において図1に示した要素と同一要素には同
符番を付している。
FIG. 5 is a schematic view of a main part of a second embodiment of the present invention. In the figure, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

【0028】本実施形態において前述の実施形態1と異
なる点は光束分割手段としてのハーフミラーのミラー面
を曲面より形成したことである。その他の構成及び光学
的作用は前述の実施形態1と略同様であり、これにより
同様な効果を得ている。
The present embodiment differs from the first embodiment in that the mirror surface of the half mirror as the light beam splitting means is formed of a curved surface. Other configurations and optical functions are substantially the same as those of the first embodiment, and thus the same effects are obtained.

【0029】即ち、同図において53はハーフミラーで
あり、ミラー面を曲面より形成しており、光偏向器4か
らの戻り光が半導体レーザー1aに入射するのを防止す
ると共に、シリンドリカルレンズ2を射出した光束を集
束光束として光偏向器4の偏向面4aに入射させてい
る。
That is, in the figure, reference numeral 53 denotes a half mirror having a curved mirror surface, which prevents the return light from the optical deflector 4 from being incident on the semiconductor laser 1a, and also controls the cylindrical lens 2 The emitted light beam is incident on the deflection surface 4a of the optical deflector 4 as a converged light beam.

【0030】本実施形態では前述の如く半導体レーザー
1aに光偏向器4からの戻り光が戻ると、その出力が不
安定になり光量変動が生じるので、ハーフミラー53の
ミラー面を曲面とすることにより、前述の実施形態1と
同様に該戻り光がアパーチャー(不図示)で半分以上ケ
ラレるようにし、また仮に光束が半導体レーザー1aに
戻るとしても発散光束として戻るので、直接半導体レー
ザー1aに入射する光束の光量を弱くすることができ、
これにより半導体レーザー1aの光量変動を効果的に防
止することができる。
In this embodiment, when the return light from the optical deflector 4 returns to the semiconductor laser 1a as described above, the output becomes unstable and the amount of light fluctuates. Therefore, the mirror surface of the half mirror 53 should be curved. As a result, as in the first embodiment, the return light is vignetted by half or more at the aperture (not shown). Even if the light beam returns to the semiconductor laser 1a, it returns as a divergent light beam, so that the light beam directly enters the semiconductor laser 1a. Light intensity of the light beam
As a result, it is possible to effectively prevent the light quantity fluctuation of the semiconductor laser 1a.

【0031】尚、各実施形態では光束分割手段として誘
電体層膜コートのハーフミラーを用いたが、これに限ら
ず、例えばプリズム形ハーフミラーを用いても本発明は
前述の実施形態と同様に適用することができる。
In each of the embodiments, a half mirror of a dielectric film coating is used as a light beam splitting means. However, the present invention is not limited to this. For example, even if a prism type half mirror is used, the present invention is similar to the above embodiment. Can be applied.

【0032】[0032]

【発明の効果】本発明によれば前述の如く入射光学手段
を射出した光束の光束幅を主走査断面内において、偏向
手段(光偏向器)の偏向面の幅よりも広くなるように形
成し、かつ該光束を主走査断面に射影したときに偏向手
段の偏向面への中心走査における光束の入射方向と該偏
向面の法線方向とが略一致するように光路内に光束分割
手段を設けることにより、該偏向手段の回転に従う光束
幅の変化量を小さく抑えることができ、これにより被走
査面上における1ライン内での光量変動量を小さく抑え
て良好なる画像を得ることができる光走査光学装置を達
成することができる。
According to the present invention, as described above, the width of the light beam emitted from the incident optical means is formed to be wider than the width of the deflecting surface of the deflecting means (optical deflector) in the main scanning section. And a light beam splitting means provided in an optical path such that, when the light beam is projected onto the main scanning section, the incident direction of the light beam in the center scan on the deflection surface of the deflection means substantially coincides with the normal direction of the deflection surface. Thus, the amount of change in the light beam width according to the rotation of the deflecting means can be suppressed to a small amount, whereby the amount of light amount fluctuation within one line on the surface to be scanned can be suppressed to a small amount to obtain a good image. An optical device can be achieved.

【図面の簡単な説明】[Brief description of the drawings]

【図1】 本発明の実施形態1の要部概略図FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

【図2】 本発明の実施形態1のハーフミラー周辺の副
走査断面図
FIG. 2 is a sectional view of a sub-scanning area around a half mirror according to the first embodiment of the present invention;

【図3】 本発明の実施形態1の主要部分の主走査断面
FIG. 3 is a main scanning sectional view of a main part according to the first embodiment of the present invention.

【図4】 光偏向器に対する入射角による光束幅の変化
を示したグラフ
FIG. 4 is a graph showing a change in a light beam width depending on an incident angle with respect to an optical deflector.

【図5】 本発明の実施形態2の要部概略図FIG. 5 is a schematic diagram of a main part of a second embodiment of the present invention.

【図6】 従来の光走査光学装置の要部概略図FIG. 6 is a schematic view of a main part of a conventional optical scanning optical device.

【符号の説明】[Explanation of symbols]

1 光源ユニット 1a 半導体レーザー 1b 変換光学素子 1c アパーチャ 2 入射光学手段(シリンドリカルレンズ) 3,53 光束分割手段(ハーフミラー) 4 偏向手段(回転多面鏡) 5 走査光学手段(fθレンズ) 6 導光手段(折り返しミラー) 7 被走査面(感光ドラム面) DESCRIPTION OF SYMBOLS 1 Light source unit 1a Semiconductor laser 1b Conversion optical element 1c Aperture 2 Incident optical means (cylindrical lens) 3,53 Beam splitting means (half mirror) 4 Deflection means (rotating polygon mirror) 5 Scanning optical means (fθ lens) 6 Light guide means (Folding mirror) 7 Scanned surface (photosensitive drum surface)

Claims (8)

【特許請求の範囲】[Claims] 【請求項1】 光源手段から射出された光束の状態を変
換光学素子により他の状態に変換し、該変換された光束
の光束断面形状をアパーチャーにより整形し、入射光学
手段で集光して光束分割手段を介して偏向手段の偏向面
上において主走査方向に長手の線状に結像させ、該偏向
手段で偏向反射された光束を該光束分割手段を介して走
査光学手段により被走査面上にスポット状に結像させ、
該被走査面上を光走査する光走査光学装置において、 該光源手段の中心、該変換光学素子の光軸、該アパーチ
ャーの中心、そして該入射光学手段の光軸は、主走査断
面に対して垂直な面内で、かつ全走査角の中心軸上に位
置するように配置され、 該入射光学手段を介した光束の光束幅は主走査断面内に
おいて、該偏向手段の偏向面の幅より広くなるように形
成され、 かつ該光束を主走査断面に射影したときに該偏向手段の
偏向面への中心走査における光束の入射方向と該偏向面
の法線方向とが略一致するように光路内に該光束分割手
段が設けられていることを特徴とする光走査光学装置。
1. A state of a light beam emitted from a light source means is converted into another state by a conversion optical element, a light beam cross-sectional shape of the converted light beam is shaped by an aperture, and the light beam is condensed by an incident optical means. An image is formed linearly in the main scanning direction on the deflection surface of the deflecting means via the splitting means, and the light beam deflected and reflected by the deflecting means is scanned by the scanning optical means via the light beam splitting means onto the surface to be scanned. To form a spot
An optical scanning optical device that optically scans the surface to be scanned, wherein a center of the light source unit, an optical axis of the conversion optical element, a center of the aperture, and an optical axis of the incident optical unit are relative to a main scanning section. The light beam width of the light beam passing through the incident optical unit is wider than the width of the deflecting surface of the deflecting unit in the main scanning section in a vertical plane and on the central axis of the entire scanning angle. And in the optical path such that, when the light beam is projected onto the main scanning section, the direction of incidence of the light beam in the central scanning on the deflecting surface of the deflecting means substantially coincides with the normal direction of the deflecting surface. Wherein the light beam splitting means is provided.
【請求項2】 前記光束分割手段は前記入射光学手段を
介した光束を前記偏向手段側に反射させ、かつ該偏向手
段で偏向反射された光束を透過させて前記走査光学手段
に入射させることを特徴とする請求項1の光走査光学装
置。
2. The light beam splitting means reflects the light beam passing through the incident optical device to the deflecting device side, and transmits the light beam deflected and reflected by the deflecting device and causes the light beam to enter the scanning optical device. 2. The optical scanning optical device according to claim 1, wherein:
【請求項3】 前記偏向手段の偏向面で偏向反射された
光束のうち前記光束分割手段で前記光源手段側へ反射さ
れる光束が、前記アパーチャーで半分以上ケラレるよう
に副走査断面内における該光束分割手段の該偏向面の法
線に対する傾斜角度を設定したことを特徴とする請求項
1又は2の光走査光学装置。
3. A light beam deflected and reflected by a deflecting surface of the deflecting means, the light beam reflected by the light beam splitting means toward the light source means being more than half vignetted by the aperture. 3. The optical scanning optical device according to claim 1, wherein an inclination angle of the light beam dividing means with respect to a normal line of the deflection surface is set.
【請求項4】 前記光束分割手段はハーフミラーより成
ることを特徴とする請求項1、2又は3の光走査光学装
置。
4. The optical scanning optical device according to claim 1, wherein said light beam splitting means comprises a half mirror.
【請求項5】 前記ハーフミラーのミラー面は平面より
成ることを特徴とする請求項4の光走査光学装置。
5. The optical scanning optical device according to claim 4, wherein a mirror surface of said half mirror is a flat surface.
【請求項6】 前記ハーフミラーのミラー面は曲面より
成ることを特徴とする請求項4の光走査光学装置。
6. The optical scanning optical device according to claim 4, wherein a mirror surface of said half mirror is a curved surface.
【請求項7】 前記変換光学素子は前記光源手段から射
出した光束の状態を略平行光束、もしくは収束光束、も
しくは発散光束に変換していることを特徴とする請求項
1の光走査光学装置。
7. The optical scanning optical device according to claim 1, wherein said conversion optical element converts a state of a light beam emitted from said light source means into a substantially parallel light beam, a convergent light beam, or a divergent light beam.
【請求項8】 前記偏向手段に入射する光束は副走査断
面内において該偏向手段の偏向面に対し斜め方向から入
射することを特徴とする請求項1の光走査光学装置。
8. The optical scanning optical apparatus according to claim 1, wherein the light beam incident on the deflecting means is incident on the deflecting surface of the deflecting means in an oblique direction in a sub-scan section.
JP9243426A 1997-08-25 1997-08-25 Light scanning optical device Pending JPH1164759A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP9243426A JPH1164759A (en) 1997-08-25 1997-08-25 Light scanning optical device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP9243426A JPH1164759A (en) 1997-08-25 1997-08-25 Light scanning optical device

Publications (1)

Publication Number Publication Date
JPH1164759A true JPH1164759A (en) 1999-03-05

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Family Applications (1)

Application Number Title Priority Date Filing Date
JP9243426A Pending JPH1164759A (en) 1997-08-25 1997-08-25 Light scanning optical device

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Country Link
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001215421A (en) * 2000-02-01 2001-08-10 Canon Inc Optical scanning optical system, optical scanner and image forming device using the same
US7057632B2 (en) * 1999-12-10 2006-06-06 Canon Kabushiki Kaisha Optical scanning apparatus, image forming apparatus, and methods of performing optical scanning using optical scanning apparatus and image forming apparatus
JP2008197187A (en) * 2007-02-09 2008-08-28 Ricoh Co Ltd Optical scanner and image forming apparatus
US7855818B2 (en) 2007-03-07 2010-12-21 Ricoh Company, Limited Optical scanning apparatus and image forming apparatus
US8233209B2 (en) 2007-01-31 2012-07-31 Ricoh Company, Limited Optical scanning device and image forming apparatus

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7057632B2 (en) * 1999-12-10 2006-06-06 Canon Kabushiki Kaisha Optical scanning apparatus, image forming apparatus, and methods of performing optical scanning using optical scanning apparatus and image forming apparatus
JP2001215421A (en) * 2000-02-01 2001-08-10 Canon Inc Optical scanning optical system, optical scanner and image forming device using the same
JP4497618B2 (en) * 2000-02-01 2010-07-07 キヤノン株式会社 Optical scanning optical system, optical scanning device, and image forming apparatus using the same
US8233209B2 (en) 2007-01-31 2012-07-31 Ricoh Company, Limited Optical scanning device and image forming apparatus
JP2008197187A (en) * 2007-02-09 2008-08-28 Ricoh Co Ltd Optical scanner and image forming apparatus
US7855818B2 (en) 2007-03-07 2010-12-21 Ricoh Company, Limited Optical scanning apparatus and image forming apparatus

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