JPH0766105B2 - Optical beam scanning device - Google Patents
Optical beam scanning deviceInfo
- Publication number
- JPH0766105B2 JPH0766105B2 JP18293284A JP18293284A JPH0766105B2 JP H0766105 B2 JPH0766105 B2 JP H0766105B2 JP 18293284 A JP18293284 A JP 18293284A JP 18293284 A JP18293284 A JP 18293284A JP H0766105 B2 JPH0766105 B2 JP H0766105B2
- Authority
- JP
- Japan
- Prior art keywords
- lens
- scanning device
- light beam
- lens system
- focal length
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/0005—Optical objectives specially designed for the purposes specified below having F-Theta characteristic
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Mechanical Optical Scanning Systems (AREA)
- Lenses (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、レーザプリンタ等に用いる光ビーム走査装置
に関するものである。TECHNICAL FIELD The present invention relates to a light beam scanning device used in a laser printer or the like.
従来、レーザプリンタ等ではレーザ発振器より発振され
たレーザビームを記録すべき情報信号によって変調し、
さらにこの変調されたレーザビームを回転多面反射鏡な
どの偏向手段で等角速度で偏向し、結像レンズ系で感光
ドラム面に集光させるように構成している。Conventionally, in a laser printer or the like, a laser beam oscillated by a laser oscillator is modulated by an information signal to be recorded,
Further, the modulated laser beam is deflected at a constant angular velocity by a deflecting means such as a rotary polygon mirror, and is focused on the photosensitive drum surface by an imaging lens system.
この場合、結像レンズ系としてｆθレンズが広く用いら
れている。In this case, the fθ lens is widely used as the imaging lens system.
このｆθレンズは、等角速度でのレーザビームの偏向を
補正してその集光スポットが走査面上で等速的に移動す
るようにするためのもので、入射瞳にθの角度で入射さ
れたレーザビームは焦点距離ｆの結像レンズの光軸から
ｆθの位置に集光することを意味してこの名称で呼ばれ
ている。The fθ lens is for correcting the deflection of the laser beam at a constant angular velocity so that the focused spot moves at a constant velocity on the scanning surface, and is incident on the entrance pupil at an angle of θ. The laser beam is called by this name, which means that the laser beam is condensed at a position of fθ from the optical axis of the imaging lens having the focal length f.
従来、このようなｆθレンズとして、例えば特開昭53−
137631号公報に開示されているよう正，負のパワーを有
する２つのレンズを組合わせたものがあるが、レンズの
後側焦点距離がレンズ系の焦点距離より長くなり、また
ｆθ特性が悪いという問題がある。Conventionally, as such an fθ lens, for example, Japanese Patent Laid-Open No. 53-
There is a combination of two lenses having positive and negative powers as disclosed in Japanese Patent No. 137631. However, the rear focal length of the lens is longer than the focal length of the lens system, and the fθ characteristic is poor. There's a problem.
また、特開昭58−5706号公報に開示されているように１
つのレンズのみでｆθ特性を実現するようにしたものが
あるが、走査面での収差が±0.67％程度であり、ｆθ特
性がそれ程良くないという問題点がある。In addition, as disclosed in JP-A-58-5706, 1
Although there is one that realizes the fθ characteristic with only one lens, there is a problem that the aberration on the scanning surface is about ± 0.67%, and the fθ characteristic is not so good.
本発明は上記のような問題点に鑑み、ｆθ特性がさらに
良好な光ビーム走査装置を提供することを目的としてい
る。In view of the above problems, it is an object of the present invention to provide a light beam scanning device having a better fθ characteristic.
本発明は、結像レンズ系として、偏向手段側が正のパワ
ーを有する第１のレンズと、走査像面側が負のパワーを
有する第２のメニスカスレンズとから構成し、レンズ系
全体の焦点距離をf,第１のレンズの焦点距離をf1,第１
のレンズの偏向手段側の面の曲率半径をr1,第２のメニ
スカスレンズの第１レンズ側の面の曲率半径をr3,入射
瞳から第１のレンズまでの距離をd0,第１のレンズと第
２のメニスカスレンズ間の距離をd2としたとき、 ａ）0.4＜f1/f＜0.7 ｂ）１＜r1/f＜2.5 ｃ）−0.4＜r3/f＜−0.2 ｄ）0.007＜d2/f＜0.045 ｅ）0.15＜d0/f＜0.3 の条件を満足するように構成したものである。The present invention comprises, as an imaging lens system, a first lens having a positive power on the deflecting means side and a second meniscus lens having a negative power on the scanning image surface side, and determines the focal length of the entire lens system. f, the focal length of the first lens is f 1 , the first lens
, R 1 is the radius of curvature of the surface of the second meniscus lens on the first lens side, r 3 is the radius of curvature of the surface of the second meniscus lens on the first lens side, and d 0 is the distance from the entrance pupil to the first lens. When the distance between the second lens and the second meniscus lens is d 2 , a) 0.4 <f 1 /f<0.7 b) 1 <r 1 /f<2.5 c) −0.4 <r 3 /f<−0.2 d) 0.007 <d 2 /f<0.045 e) 0.15 <d 0 /f<0.3.
第１図は本発明の一実施例を示す結像レンズ系の構成図
であり、１は入射瞳、２は平行光束、３は第１レンズ、
４は第２レンズである。FIG. 1 is a configuration diagram of an imaging lens system showing an embodiment of the present invention, in which 1 is an entrance pupil, 2 is a parallel light beam, 3 is a first lens,
Reference numeral 4 is a second lens.
第１レンズ３は正のパワーを有する両凸レンズであり、
また第２レンズ４は負のパワーを有するメニスカスレン
ズである。第２レンズ４は曲率半径の小さい凹面が第１
レンズ３の側に向けられている。The first lens 3 is a biconvex lens having positive power,
The second lens 4 is a meniscus lens having negative power. The second lens 4 has a concave surface with a small radius of curvature as the first
It is directed toward the lens 3.
ここで、これら第１レンズ３および第２レンズ４におけ
る各屈折面の曲率半径を入射瞳１に近い面から順にr1,r
2,r3,r4とし、各屈折面間の距離を入射瞳１に近い順にd
1,d2,d3とする。また、入射瞳１から第１レンズ３まで
の距離をd0とする。さらに、結像レンズ系全体の焦点距
離をｆ、第１レンズ３の焦点距離をf1とする。Here, the radii of curvature of the refracting surfaces of the first lens 3 and the second lens 4 are set to r 1 and r in order from the surface close to the entrance pupil 1.
2 , r 3 , r 4 and the distance between the refracting surfaces is d in the order of being closer to the entrance pupil 1.
Let 1 , d 2 , d 3 . Further, the distance from the entrance pupil 1 to the first lens 3 is d 0 . Further, the focal length of the entire imaging lens system is f, and the focal length of the first lens 3 is f 1 .
すると、この発明の結像レンズ系は次の条件を満足する
ように構成される。Then, the imaging lens system of the present invention is configured to satisfy the following conditions.
ａ）0.4＜f1/f＜0.7 ｂ）１＜r1/f＜2.5 ｃ）−0.4＜r3/f＜−0.2 ｄ）0.007＜d2/f＜0.045 ｅ）0.15＜d0/f＜0.3 このうち条件ａ）、歪曲収差と像面の平坦性を維持する
上で必要なパワー配置を示している。条件ｂ）は負の歪
曲収差を発生させるために重要な条件であり、上限値を
越えると負の歪曲が不足となり、下限値を下まわると像
面がアンダーになる。a) 0.4 <f 1 /f<0.7 b) 1 <r 1 /f<2.5 c) −0.4 <r 3 /f<−0.2 d) 0.007 <d 2 /f<0.045 e) 0.15 <d 0 / f <0.3 Of these, condition a) shows the power allocation necessary for maintaining distortion and flatness of the image plane. The condition b) is an important condition for generating negative distortion. When the value exceeds the upper limit, the negative distortion becomes insufficient, and when the value goes below the lower limit, the image surface becomes under.
条件ｃ）は像面の平坦性を維持するために重要な条件で
あり、上限値を越えると像面がオーバーになり、下限値
を下回るとアンダーになる。The condition c) is an important condition for maintaining the flatness of the image surface. If the upper limit value is exceeded, the image surface will be over, and if the lower limit value is exceeded, the image surface will be under.
条件ｄ）は上限を越えると負の歪曲が不足して像面もオ
ーバーとなる。また下限値を下回ると、物理的にレンズ
配置が不可能となる。When the condition d) exceeds the upper limit, the negative distortion is insufficient and the image plane becomes over. On the other hand, when the value is below the lower limit, it becomes physically impossible to dispose the lens.
条件ｅ）は上限値を越えるとレンズ系が大きくなり、下
限値を下回ると像面がアンダーになるので、この範囲が
最適である。If the condition e) exceeds the upper limit, the size of the lens system becomes large, and if it falls below the lower limit, the image surface becomes undersized. Therefore, this range is optimal.
ここで、このような結像レンズ系、すなわち、上記条件
ａ）〜ｅ）を全て満足する結像レンズ系で光を集光させ
る場合を考え、例えば、この結像レンズ系の走査角度を
±22.5度、使用波長をλ＝780mm、第１のレンズの屈折
率n1および第２のレンズの屈折率n2をn1＝n2＝1.5112
（光学ガラスとしてBK7の材料を使用）とし、さらにｆ
＝330mm,r1＝427、204,r2＝−138、891,r3＝−79、180,
r4＝−112、480,d0＝76、18,d1＝10,d2＝３、81,d3＝10
とした場合、ｆθ特性は第２図に示すように0.1％以内
となる。Now, let us consider a case where light is condensed by such an imaging lens system, that is, an imaging lens system that satisfies all of the above conditions a) to e). 22.5 degrees, wavelength used is λ = 780 mm, refractive index n1 of the first lens and refractive index n2 of the second lens are n1 = n2 = 1.5112
(Using BK7 material as optical glass), and f
= 330mm, r 1 = 427,204, r 2 = -138,891, r 3 = -79,180,
r 4 = -112,480, d 0 = 76,18, d 1 = 10, d 2 = 3,81, d 3 = 10
In such a case, the fθ characteristic is within 0.1% as shown in FIG.
また、像面の平坦特性は第３図に示すように、タンジェ
ンシャル方向（Ｔ）では±4mm以内となり、サジタル方
向（Ｓ）では−10mm以内となる。The flatness of the image plane is within ± 4 mm in the tangential direction (T) and within -10 mm in the sagittal direction (S), as shown in FIG.
ところで、第１図の結像レンズ系において、この系の後
側（走査面側）に円筒鏡を設けることにより、倒れ補正
光学系を形成することができる。このとき、円筒鏡の位
置を走査面側に近い位置に設定することにより、サジタ
リ像面歪曲は著しく小さくなる。By the way, in the image forming lens system of FIG. 1, a tilting correction optical system can be formed by providing a cylindrical mirror on the rear side (scanning surface side) of this system. At this time, by setting the position of the cylindrical mirror to a position close to the scanning surface side, the sagittal image plane distortion is significantly reduced.
例えば、第２レンズ４の後側の150mmの位置に入射瞳１
と走査面が共役になるような円筒鏡を設置すると、サジ
タル像面の平坦特性は第４図に示すように−5mm以内に
著しく小さくなる。For example, at the position 150 mm behind the second lens 4, the entrance pupil 1
When a cylindrical mirror is installed so that the scanning plane is conjugate with the scanning plane, the flatness of the sagittal image plane becomes extremely small within -5 mm as shown in FIG.
以上の説明から明らかなように本発明によれば、ｆθ特
性が0.1％以内の光ビーム走査装置を実現できるという
効果がある。As is apparent from the above description, according to the present invention, there is an effect that a light beam scanning device having an fθ characteristic of 0.1% or less can be realized.
第１図は本発明における結像レンズ系の一実施例を示す
図、第２図はｆθ特性図、第３図は平坦特性図、第４図
は第１図の結像レンズ系に円筒鏡を付加したときの平坦
特性図である。 １……入射瞳、２……平行光速、３……第１レンズ、４
……第２レンズ。FIG. 1 is a diagram showing an embodiment of an imaging lens system according to the present invention, FIG. 2 is an f.theta. Characteristic diagram, FIG. 3 is a flat characteristic diagram, and FIG. 4 is a cylindrical mirror in the imaging lens system of FIG. It is a flat characteristic diagram when is added. 1 ... Entrance pupil, 2 ... Parallel light speed, 3 ... First lens, 4
...... Second lens.
Claims (1)
た光ビームを走査像面に集光させるレンズ系とを備えた
光ビーム走査装置において、前記レンズ系は偏向手段側
が正のパワーを有する第１のレンズと、走査像面側が負
のパワーを有する第２のメニスカスレンズとから構成
し、レンズ系全体の焦点距離をf,第１のレンズの焦点距
離をf1,第１のレンズの偏向手段側の面の曲率半径をr1,
第２のメニスカスレンズの第１レンズ側の面の曲率半径
をr3,入射瞳から第１のレンズまでの距離をd0,第１のレ
ンズと第２のメニスカスレンズ間の距離をd2としたと
き、 ａ）0.4＜f1/f＜0.7 ｂ）１＜r1/f＜2.5 ｃ）−0.4＜r3/f＜−0.2 ｄ）0.007＜d2/f＜0.045 ｅ）0.15＜d0/f＜0.3 の関係を満足することを特徴とする光ビーム走査装置。1. A light beam scanning device comprising a deflecting means for deflecting a light beam and a lens system for condensing the deflected light beam on a scanning image plane, wherein the lens system has a positive power on the deflecting means side. And a second meniscus lens having a negative power on the scanning image plane side. The focal length of the entire lens system is f, the focal length of the first lens is f 1 , and the first lens is r 1 the radius of curvature of the surface of the deflecting means side,
The radius of curvature of the surface of the second meniscus lens on the first lens side is r 3 , the distance from the entrance pupil to the first lens is d 0 , and the distance between the first lens and the second meniscus lens is d 2 . A) 0.4 <f 1 /f<0.7 b) 1 <r 1 /f<2.5 c) −0.4 <r 3 /f<−0.2 d) 0.007 <d 2 /f<0.045 e) 0.15 <d A light beam scanning device characterized by satisfying a relationship of 0 / f <0.3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18293284A JPH0766105B2 (en) | 1984-08-31 | 1984-08-31 | Optical beam scanning device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18293284A JPH0766105B2 (en) | 1984-08-31 | 1984-08-31 | Optical beam scanning device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6161113A JPS6161113A (en) | 1986-03-28 |
| JPH0766105B2 true JPH0766105B2 (en) | 1995-07-19 |
Family
ID=16126891
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18293284A Expired - Fee Related JPH0766105B2 (en) | 1984-08-31 | 1984-08-31 | Optical beam scanning device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0766105B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6350810A (en) * | 1986-08-21 | 1988-03-03 | Seiko Epson Corp | Optical scanner |
-
1984
- 1984-08-31 JP JP18293284A patent/JPH0766105B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6161113A (en) | 1986-03-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |