JP4654072B2 - Scanning optical system - Google Patents
Scanning optical system Download PDFInfo
- Publication number
- JP4654072B2 JP4654072B2 JP2005165469A JP2005165469A JP4654072B2 JP 4654072 B2 JP4654072 B2 JP 4654072B2 JP 2005165469 A JP2005165469 A JP 2005165469A JP 2005165469 A JP2005165469 A JP 2005165469A JP 4654072 B2 JP4654072 B2 JP 4654072B2
- Authority
- JP
- Japan
- Prior art keywords
- scanning
- lens
- optical system
- curvature
- deflector
- 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
Landscapes
- Laser Beam Printer (AREA)
- Mechanical Optical Scanning Systems (AREA)
- Lenses (AREA)
- Facsimile Scanning Arrangements (AREA)
Description
本発明は、レーザープリンタ等に内蔵されるレーザースキャンニングユニット(ＬＳＵ)に用いられる走査光学系、及びその設計方法に関する。 The present invention relates to a scanning optical system used in a laser scanning unit (LSU) built in a laser printer or the like, and a design method thereof.
走査光学系は、レーザー光源からの光束をポリゴンミラー等の偏向器により偏向、走査させ、ｆθレンズのような走査レンズを介して感光体ドラム等の走査対象面上にスポットとして結像させる。感光体ドラム上のスポットは、ポリゴンミラーの回転に伴って主走査方向に走査し、この際レーザー光をオンオフ変調することにより走査対象面上に静電潜像を形成する。 The scanning optical system deflects and scans a light beam from a laser light source by a deflector such as a polygon mirror, and forms an image as a spot on a surface to be scanned such as a photosensitive drum through a scanning lens such as an fθ lens. The spot on the photosensitive drum is scanned in the main scanning direction as the polygon mirror rotates, and an electrostatic latent image is formed on the surface to be scanned by performing on-off modulation of the laser beam.
近年、レーザープリンタの小型化や低価格化の要求を受けて、コンパクトで低コストのＬＳＵが求められている。低コスト化のため、この種の走査レンズは、一般にプラスチックの射出成型により製造される。また、コンパクトで低コストのＬＳＵを提供するためには、走査レンズのサイズを小さくする必要がある。例えば特許文献１〜３には、走査レンズの主走査方向の幅を小さくするため、走査レンズをポリゴンミラーに近づけて配置した走査光学系が開示されている。
しかしながら、上記の各文献の走査光学系は、走査レンズを小型化しつつ、良好な光学性能を維持するため、サグ量の非球面成分(軸上の曲率半径を持つ球面からの形状のずれ量)が大きく、かつ、高次の非球面係数による複雑な形状の非球面を使用している。このため、レンズの製造誤差に対する光学性能の劣化の度合い(製造誤差感度)が大きく、非球面形状がわずかに設計値からずれても光学性能が大きく劣化する。したがって、製造誤差の許容量が小さく製造が困難になるという問題がある。 However, the scanning optical system of each of the above-mentioned documents is designed to reduce the size of the scanning lens and maintain good optical performance, so that the aspherical component of the sag amount (the amount of deviation of the shape from the spherical surface having the on-axis radius of curvature) And an aspherical surface having a complicated shape with a higher-order aspherical coefficient is used. For this reason, the degree of deterioration of the optical performance (manufacturing error sensitivity) with respect to the manufacturing error of the lens is large, and the optical performance is greatly deteriorated even if the aspherical shape is slightly deviated from the design value. Therefore, there is a problem that manufacturing tolerance is small and manufacturing is difficult.
具体的には、小型化により製造誤差感度が高くなると、成型時の型のズレにより走査レンズの第１面と第２面との偏心(中心軸のズレ)が生じた際の主走査方向の像面の傾きや、離型後のプラスチックの収縮による弓なりの変形(ベンディング)による主走査方向の像面湾曲が顕著になる。 Specifically, when the manufacturing error sensitivity becomes higher due to the miniaturization, the deviation in the main scanning direction when the first surface and the second surface of the scanning lens are decentered (displacement of the central axis) due to the displacement of the mold at the time of molding. Inclination of the image plane and curvature of field in the main scanning direction due to bow-shaped deformation (bending) due to shrinkage of the plastic after mold release become significant.
本発明は、上述した従来技術の問題点に鑑みてなされたものであり、走査レンズの小型化を図りつつ、レンズ形状が設計値からずれた場合にも性能の劣化が少ない走査光学系、及びその設計方法を提供することを目的とする。 The present invention has been made in view of the above-described problems of the prior art, and is intended to reduce the size of the scanning lens, and when the lens shape deviates from the design value, the scanning optical system has little degradation in performance, and It aims at providing the design method.
走査レンズの設計上の光学性能と製造難易度はトレードオフの関係にあり、設計上の光学性能を良くするとレンズの製造誤差感度が高くなって製造が困難になり、一方で製造を容易にするために製造誤差感度を低くしすぎると光学性能が低くなる。本発明にかかる走査光学系は、設計上の光学性能と製造誤差感度とのバランスをとるよう設計されている。 There is a trade-off between the design optical performance and the manufacturing difficulty of the scanning lens. When the design optical performance is improved, the manufacturing error sensitivity of the lens becomes high and the manufacturing becomes difficult. Therefore, if the manufacturing error sensitivity is too low, the optical performance is lowered. The scanning optical system according to the present invention is designed to balance the design optical performance and the manufacturing error sensitivity.
すなわち、本発明の走査光学系は、光束を発生する光源部と、光源部から発する光束を偏向させる偏向器と、偏向器により偏向された光束を被走査面上で主走査方向に走査するスポットとして収束させる結像光学系とを備え、結像光学系は、単数または複数の単レンズから構成され、最も偏向器に近い位置にある第１走査レンズの少なくとも一面は非球面であり、偏向器の偏向面から第１走査レンズまでの距離をＬ[mm]、結像光学系の半画角をθ[rad.]、走査幅（半幅）をＷ[mm]、第１走査レンズの非球面の光軸上の曲率をＣ、主走査方向の有効走査領域内における曲率の最大値と最小値との差をΔＣとし、前記結像光学系の主走査断面における屈折力をφ ａ [dptr.]、前記第１走査レンズの第１面の屈折力を
φ １ [dptr.]としたとき、以下の条件(１)、(２)、(３)を満たすことを特徴とする。
θＬ＜０．１５Ｗ …(１)
−０．９＜ΔＣ／Ｃ＜−０．６ …(２)
−０．７３＜φ ａ ／φ １ ≦−０．６２ …(３)
That is, the scanning optical system of the present invention includes a light source unit that generates a light beam, a deflector that deflects the light beam emitted from the light source unit, and a spot that scans the light beam deflected by the deflector in the main scanning direction on the surface to be scanned. And the imaging optical system is composed of one or a plurality of single lenses, and at least one surface of the first scanning lens closest to the deflector is an aspherical surface. The distance from the deflection surface to the first scanning lens is L [mm], the half angle of view of the imaging optical system is θ [rad.], The scanning width (half width) is W [mm], and the aspherical surface of the first scanning lens C is the curvature on the optical axis, ΔC is the difference between the maximum value and the minimum value of the curvature in the effective scanning area in the main scanning direction, and the refractive power in the main scanning section of the imaging optical system is φ a [dptr .], The refractive power of the first surface of the first scanning lens
When φ 1 [dptr.], the following conditions (1), (2 ), and (3) are satisfied.
θL <0.15W (1)
−0.9 <ΔC / C <−0.6 (2)
−0.73 <φ a / φ 1 ≦ −0.62 (3)
一方、本発明にかかる走査光学系の設計方法は、光源部から発して偏向器により偏向された光束を結像光学系により被走査面上で主走査方向に走査するスポットとして収束させる走査光学系の設計方法であって、前記結像光学系のうち最も前記偏向器側に配置される第１走査レンズとして、少なくとも一面が非球面のレンズを採用すると共に、前記偏向器の偏向面から前記第１走査レンズまでの距離をＬ[mm]、前記結像光学系の半画角をθ[rad.]、走査幅（半幅）をＷ[mm] 、前記第１走査レンズの非球面の光軸上の曲率をＣ、主走
査方向の有効走査領域内における曲率の最大値と最小値との差をΔＣとし、前記結像光学系の主走査断面における屈折力をφ ａ [dptr.]、前記第１走査レンズの第１面の屈折力を
φ １ [dptr.]としたとき、以下の条件(１)、(２)、（３）を満たすよう設計することを特
徴とする走査光学系の設計方法。
θＬ＜０．１５Ｗ …(１)
−０．９＜ΔＣ／Ｃ＜−０．６ …(２)
−０．７３＜φ ａ ／φ １ ≦−０．６２ …(３)
On the other hand, a scanning optical system design method according to the present invention is a scanning optical system that converges a light beam emitted from a light source unit and deflected by a deflector as a spot scanned in the main scanning direction on the surface to be scanned by the imaging optical system. In the design method, at least one aspherical surface lens is employed as the first scanning lens arranged closest to the deflector in the imaging optical system, and the first scanning lens is disposed from the deflecting surface of the deflector. The distance to one scanning lens is L [mm], the half angle of view of the imaging optical system is θ [rad.], The scanning width (half width) is W [mm], and the aspherical optical axis of the first scanning lens Upper curvature is C, main run
The difference between the maximum value and the minimum value of the curvature in the effective scanning area in the scanning direction is ΔC, the refractive power in the main scanning section of the imaging optical system is φ a [dptr.], And the first scanning lens The refractive power of the surface
When φ 1 [dptr.] is selected, it should be designed to satisfy the following conditions (1), (2), and (3).
Design method of scanning optical system.
θL <0.15W (1)
−0.9 <ΔC / C <−0.6 (2)
−0.73 <φ a / φ 1 ≦ −0.62 (3)
本発明の走査光学系によれば、所定の条件を満たすことにより、小型化を達成しつつ、良好な光学性能を確保し、かつ、多少の製造誤差が生じても光学性能が著しく劣化することがなく、製造を容易にすることができる。 According to the scanning optical system of the present invention, by satisfying predetermined conditions, while achieving miniaturization, good optical performance is ensured, and even if some manufacturing errors occur, the optical performance is significantly deteriorated. The manufacturing can be facilitated.
また、本発明の走査光学系の設計方法によれば、従来考慮されていなかった製造誤差感度を設計パラメータとして加えることにより、小型の走査レンズにおいても光学性能と製造難易度とのバランスのとれた設計が可能となる。 In addition, according to the scanning optical system design method of the present invention, by adding the manufacturing error sensitivity that has not been considered in the past as a design parameter, a balance between optical performance and manufacturing difficulty can be achieved even in a small scanning lens. Design becomes possible.
以下、本発明にかかる走査光学系の実施形態について説明する。始めに本発明の実施形態について説明し、曲率半径及び非球面量と光学性能及び製造誤差感度の関係について説明し、続いて実施形態に基づく具体的な実施例を３例示し、最後に２つの比較例を示し、これとの比較により実施例の効果を説明する。実施例及び比較例の走査光学系は、レーザープリンタのレーザー走査ユニットに使用され、入力される描画信号にしたがってON/OFF変調されたレーザー光を感光体ドラム等の走査対象面上で走査させ、静電潜像を形成する。この明細書では、走査対象面上でスポットが走査する方向を主走査方向、これに直交する方向を副走査方向と定義し、各光学素子の形状、パワーの方向性は、走査対象面上での方向を基準に説明する。主走査方向に対して平行で結像光学系の光軸を含む平面を主走査面という。 Embodiments of a scanning optical system according to the present invention will be described below. First, the embodiment of the present invention will be described, the relationship between the radius of curvature and the amount of aspheric surface, the optical performance, and the manufacturing error sensitivity will be described, followed by three specific examples based on the embodiment, and finally two A comparative example is shown, and the effect of the embodiment will be described by comparison with the comparative example. The scanning optical system of the example and the comparative example is used in a laser scanning unit of a laser printer, and scans a scanning target surface such as a photosensitive drum with laser light that is ON / OFF modulated according to an input drawing signal. An electrostatic latent image is formed. In this specification, the direction in which the spot scans on the surface to be scanned is defined as the main scanning direction, and the direction perpendicular thereto is defined as the sub-scanning direction. The shape and power direction of each optical element are defined on the surface to be scanned. The direction will be described as a reference. A plane parallel to the main scanning direction and including the optical axis of the imaging optical system is called a main scanning surface.
実施形態の走査光学系は、主走査面内の平面図である図１(後述の実施例１の構成を示す)に示されるように、光源である半導体レーザー１０から発した発散光をコリメートレンズ１１により略平行光束とし、副走査方向に正のパワーを有するシリンドリカルレンズ１２を介して偏向器であるポリゴンミラー１４に入射させる。ポリゴンミラー１４の反射面１４ａで反射、偏向されたレーザー光は、結像光学系を構成する走査レンズ(ｆθレンズ)２０を介して収束され、走査対象面３０上に主走査方向に走査するスポットを形成する。 As shown in FIG. 1 (showing the configuration of Example 1 to be described later) which is a plan view in the main scanning plane, the scanning optical system of the embodiment emits divergent light emitted from a semiconductor laser 10 as a light source. 11 is made into a substantially parallel light beam and is incident on a polygon mirror 14 as a deflector through a cylindrical lens 12 having a positive power in the sub-scanning direction. The laser beam reflected and deflected by the reflecting surface 14a of the polygon mirror 14 is converged through a scanning lens (fθ lens) 20 constituting an imaging optical system, and is a spot that scans on the scanning target surface 30 in the main scanning direction. Form.
半導体レーザー１０及びコリメートレンズ１１は光源部を構成する。シリンドリカルレンズ１２は、コリメートレンズ１１側のレンズ面が副走査方向にのみ正のパワーを持つシリンダー面、ポリゴンミラー１４側のレンズ面が平面として構成されている。シリンドリカルレンズ１２のパワーは、シリンドリカルレンズ１２により形成される線像がポリゴンミラー１４の反射面１４ａの近傍に位置するよう定められている。 The semiconductor laser 10 and the collimating lens 11 constitute a light source unit. The cylindrical lens 12 is configured such that the lens surface on the collimating lens 11 side is a cylinder surface having a positive power only in the sub-scanning direction, and the lens surface on the polygon mirror 14 side is a flat surface. The power of the cylindrical lens 12 is determined so that the line image formed by the cylindrical lens 12 is positioned in the vicinity of the reflecting surface 14 a of the polygon mirror 14.
ポリゴンミラー１４で反射された光束は、主走査方向には図１に示すようにほぼ平行光として、副走査方向には発散光としてｆθレンズ２０に入射する。ｆθレンズ２０は、ポリゴンミラー１４側から第１走査レンズ２１と第２走査レンズ２２とが配列して構成されている。第１走査レンズ２１の少なくとも１面は非球面であり、第１走査レンズ２１と第２走査レンズ２２とは、いずれもプラスチックレンズである。 The light beam reflected by the polygon mirror 14 enters the fθ lens 20 as substantially parallel light in the main scanning direction as shown in FIG. 1 and as divergent light in the sub scanning direction. The fθ lens 20 includes a first scanning lens 21 and a second scanning lens 22 arranged from the polygon mirror 14 side. At least one surface of the first scanning lens 21 is an aspheric surface, and the first scanning lens 21 and the second scanning lens 22 are both plastic lenses.
実施形態の走査光学系では、ｆθレンズ２０の第１走査レンズ２１がポリゴンミラー１４に近接して配置されており、これにより、レンズの主走査方向の幅を小さくしている。また、第１走査レンズの設計に当たっては、小型化により製造誤差感度が大きくなり過ぎないように、光学性能と製造誤差感度とのバランスを考慮している。 In the scanning optical system of the embodiment, the first scanning lens 21 of the fθ lens 20 is disposed close to the polygon mirror 14, thereby reducing the width of the lens in the main scanning direction. In designing the first scanning lens, the balance between the optical performance and the manufacturing error sensitivity is taken into consideration so that the manufacturing error sensitivity does not become too large due to downsizing.
製造誤差感度は、レンズ設計時にレンズの各面の曲率半径と非球面量をコントロールすることにより、製造上問題のないレベルまで下げることが可能である。ここで実施形態の第１走査レンズ２１に相当するレンズを例にして、面形状と光学性能及び製造誤差感度との関係を説明する。 The manufacturing error sensitivity can be lowered to a level where there is no problem in manufacturing by controlling the radius of curvature and the amount of aspheric surface of each surface of the lens when designing the lens. Here, the relationship between the surface shape, the optical performance, and the manufacturing error sensitivity will be described using a lens corresponding to the first scanning lens 21 of the embodiment as an example.
以下の表１は、第１走査レンズの焦点距離を一定にして第１面と第２面との曲率半径を変更(ベンディング)した場合に、光学性能と製造誤差感度とがどのように変化するかを示す。表１の各レンズは、第１面が凹の球面、第２面が凸の回転対称非球面のメニスカスレンズである。回転対称非球面の形状は、光軸からの距離ｈにおける光軸と非球面との交点での接平面からのサグ量Ｘ(ｈ)で表すことができ、そのサグ量は、以下の式で表される。
X(h)＝h2／［r{1＋√(1−(κ＋1)h2／r2)}］＋A4h4＋A6h6＋A8h8＋A10h10＋A12h12
Table 1 below shows how the optical performance and the manufacturing error sensitivity change when the radius of curvature of the first surface and the second surface is changed (bending) with the focal length of the first scanning lens constant. Indicate. Each lens in Table 1 is a rotationally symmetric aspheric meniscus lens having a concave first surface and a convex second surface. The shape of the rotationally symmetric aspherical surface can be expressed by the sag amount X (h) from the tangent plane at the intersection of the optical axis and the aspherical surface at a distance h from the optical axis, and the sag amount is expressed by the following equation: expressed.
X (h) = h 2 / [r {1 + √ (1− (κ + 1) h 2 / r 2 )}] + A 4 h 4 + A 6 h 6 + A 8 h 8 + A 10 h 10 + A 12 h 12
上式中、ｒは光軸上の曲率半径、κは円錐係数、A4,A6,A8,A10,A12はそれぞれ４次、６次、８次、１０次、１２次の非球面係数である。表１には、各レンズ面の曲率半径ｒ、円錐係数κ、非球面係数A4,A6,A8,A10,A12、面間の光軸上の距離ｄ、使用波長780nmでの屈折率ｎが表示されると共に、それぞれの構成における光学性能として主走査方向の像面湾曲(主像面湾曲)、製造誤差感度として偏心誤差感度及び屈折力誤差感度が示されている。像面湾曲は、焦点位置の近軸像面からの光軸方向のズレ、偏心誤差感度は、第１面と第２面とが主走査方向に０．１ｍｍ相対的に偏心した際の主走査像面の傾き、屈折力誤差感度は、第１面と第２面との屈折力がそれぞれ設計値から０．１dprt.変化した際に発生する像面湾曲の変化量である。なお、以下の表中の記号Ｅは、Ｅの右側の数値を指数とする１０の累乗を示し、例えば、左端列のレンズの第２面のＡ4の値「5.65743E-06」は「5.65743×10-06」を意味する。 In the above equation, r is the radius of curvature on the optical axis, κ is the conic coefficient, and A 4 , A 6 , A 8 , A 10 , A 12 are the 4th, 6th, 8th, 10th, and 12th non-orders respectively. Spherical coefficient. Table 1 shows the curvature radius r of each lens surface, the conical coefficient κ, the aspherical coefficients A 4 , A 6 , A 8 , A 10 , A 12 , the distance d on the optical axis between the surfaces, and the wavelength used at 780 nm. In addition to displaying the refractive index n, the optical performance in each configuration includes field curvature in the main scanning direction (main field curvature), and eccentricity error sensitivity and refractive power error sensitivity as manufacturing error sensitivity. The curvature of field is the deviation of the focal position from the paraxial image plane in the optical axis direction, and the eccentricity error sensitivity is the main scanning when the first surface and the second surface are relatively decentered by 0.1 mm in the main scanning direction. Image plane tilt and refractive power error sensitivity are the amounts of change in field curvature that occur when the refractive powers of the first and second surfaces change 0.1 dprt. Incidentally, the symbols E in the table below, indicates the power of 10 to the right of the numeric index of E, for example, the value of A 4 on the second side of the leftmost column lens "5.65743E-06" is "5.65743 × 10 -06 ”.
また、図２は、表１の値をグラフ化したものであり、図２(Ａ)は、第１面の曲率半径と主走査方向の像面湾曲、偏心誤差感度との関係を示すグラフ、図２(Ｂ)は第１面の曲率半径と屈折力誤差感度との関係を示すグラフである。第１面の曲率半径を小さくすると(きついメニスカス形状にすると)、設計上の光学性能は向上するが、製造誤差感度は大きくなる。反対に、第１面の曲率半径を大きくすると(緩いメニスカス形状にすると)、製造誤差感度は小さくなるが、設計上の光学性能は悪化する。 FIG. 2 is a graph showing the values in Table 1. FIG. 2A is a graph showing the relationship between the radius of curvature of the first surface, curvature of field in the main scanning direction, and eccentricity error sensitivity. FIG. 2B is a graph showing the relationship between the radius of curvature of the first surface and the refractive power error sensitivity. If the radius of curvature of the first surface is reduced (a tight meniscus shape), the designed optical performance is improved, but the manufacturing error sensitivity is increased. On the other hand, when the radius of curvature of the first surface is increased (when a gentle meniscus shape is used), the manufacturing error sensitivity decreases, but the optical performance in design deteriorates.
以下の表２は、第１走査レンズの第１面の曲率半径を一定にして非球面量を変えた場合(ここでは簡単のために４次の非球面係数のみを変化させた)に、光学性能と製造誤差感度とがどのように変化するかを示す。表２の各レンズは、第１面が凹の回転対称非球面、第２面が凸の回転対称非球面のメニスカスレンズである。表２には、表１と同様に各レンズの設計値と、光学性能として主走査像面湾曲と、製造誤差感度として偏心誤差感度及び屈折力誤差感度が示されている。なお、第１面非球面量は、光軸から２０ｍｍ離れた位置における近軸球面からのサグ差である。 Table 2 below shows the optical characteristics when the aspherical amount is changed while keeping the curvature radius of the first surface of the first scanning lens constant (here, only the fourth-order aspherical coefficient is changed for the sake of simplicity). It shows how performance and manufacturing error sensitivity change. Each lens in Table 2 is a meniscus lens having a rotationally symmetric aspheric surface with a concave first surface and a rotationally symmetric aspheric surface with a convex second surface. Table 2 shows the design values of each lens, the main scanning field curvature as optical performance, and the decentration error sensitivity and refractive power error sensitivity as manufacturing error sensitivities, as in Table 1. The first surface aspheric surface amount is a sag difference from the paraxial spherical surface at a position 20 mm away from the optical axis.
また、図３は、表２の値をグラフ化したものであり、図３(Ａ)は、第１面の非球面量と主走査像面湾曲、偏心誤差感度との関係を示すグラフ、図３(Ｂ)は第１面の非球面量と屈折力誤差感度との関係を示すグラフである。第１面の非球面量を大きくすると、設計上の光学性能は向上するが、製造誤差感度は大きくなる。反対に、第１面の非球面量を小さくすると、製造誤差感度は小さくなるが、設計上の光学性能は悪化する。 FIG. 3 is a graph showing the values in Table 2. FIG. 3A is a graph showing the relationship between the amount of aspherical surface on the first surface, main scanning field curvature, and eccentric error sensitivity. 3 (B) is a graph showing the relationship between the aspherical amount of the first surface and the refractive power error sensitivity. Increasing the aspheric amount of the first surface improves the optical performance in design, but increases the manufacturing error sensitivity. On the other hand, if the amount of aspherical surface of the first surface is reduced, the sensitivity of manufacturing error is reduced, but the designed optical performance is deteriorated.
このように，同じ設計仕様のレンズであっても曲率半径と非球面量の選び方で設計上の光学性能と製造誤差感度が変化する。実施形態では、実用上問題ない光学性能を確保しつつ、できるだけ製造誤差感度を下げるため、光学性能と製造誤差感度とをパラメータとして、これらのバランスを取るよう設計している。 As described above, even in the case of lenses having the same design specifications, the design optical performance and the manufacturing error sensitivity change depending on how the radius of curvature and the amount of aspheric surface are selected. In the embodiment, in order to reduce the manufacturing error sensitivity as much as possible while ensuring optical performance that is not a problem in practice, the optical performance and the manufacturing error sensitivity are used as parameters to design the balance.
すなわち、実施形態の走査光学系は、ポリゴンミラー(偏向器)１４の偏向面から第１走査レンズ２１までの距離をＬ[mm]、ｆθレンズ(結像光学系)２０の半画角をθ[rad.]、走査幅（半幅）をＷ[mm]、第１走査レンズ２１の非球面の光軸上の曲率をＣ、主走査方向の有効走査領域内における曲率の最大値と最小値との差をΔＣとしたとき、以下の条件(１)、(２) を満たす。
θＬ＜０．１５Ｗ …(１)
−０．９＜ΔＣ／Ｃ＜−０．６ …(２)
That is, in the scanning optical system of the embodiment, the distance from the deflection surface of the polygon mirror (deflector) 14 to the first scanning lens 21 is L [mm], and the half angle of view of the fθ lens (imaging optical system) 20 is θ. [rad.], the scanning width (half width) is W [mm], the curvature on the optical axis of the aspherical surface of the first scanning lens 21 is C, and the maximum and minimum values of the curvature in the effective scanning area in the main scanning direction When the difference of Δ is ΔC, the following conditions (1) and (2) are satisfied.
θL <0.15W (1)
−0.9 <ΔC / C <−0.6 (2)
条件(１)は、ｆθレンズ２０が広角であり、かつ、第１走査レンズ２１がポリゴンミラー１４に近接して配置されていることを規定する。条件(１)を満たさない場合には、広角ではなく、小型化が達成できない。条件(１)を満たさないレンズは、光学性能のみを考慮して設計しても製造誤差感度が高くならず、本発明を適用する必要がない。 Condition (1) defines that the fθ lens 20 is wide-angle and the first scanning lens 21 is disposed close to the polygon mirror 14. If the condition (1) is not satisfied, the angle is not wide and the size reduction cannot be achieved. A lens that does not satisfy the condition (1) does not have high manufacturing error sensitivity even when designed in consideration of only optical performance, and it is not necessary to apply the present invention.
条件(２)は、第１走査レンズ２１の非球面による主走査断面での曲率変化量を規定する。条件(２)の下限を下回ると非球面量が大きくなりすぎて製造誤差感度が高くなり、上限を超えると非球面量が小さくなりすぎて設計上の光学性能が悪くなる。条件(２)を満たすことにより、第１走査レンズ２１の非球面量に関して、製造誤差感度と光学性能とのバランスをとることができる。 Condition (2) defines the amount of curvature change in the main scanning section due to the aspherical surface of the first scanning lens 21. If the lower limit of condition (2) is not reached, the amount of aspherical surface becomes too large and the sensitivity of manufacturing error increases, and if the upper limit is exceeded, the amount of aspherical surface becomes too small and the optical performance in design deteriorates. By satisfying the condition (2), it is possible to balance the manufacturing error sensitivity and the optical performance with respect to the aspheric amount of the first scanning lens 21.
また、実施形態の走査光学系は、ｆθレンズ２０の全系の主走査断面における屈折力をφa[dptr.]、第１走査レンズ２１の第１面の屈折力をφ1[dptr.]としたとき、以下の条件(３)を満たす。
−０．７３＜φa／φ1＜−０．５６ …(３)
In the scanning optical system of the embodiment, the refractive power in the main scanning section of the entire fθ lens 20 is φ a [dptr.], And the refractive power of the first surface of the first scanning lens 21 is φ 1 [dptr.]. The following condition (3) is satisfied.
−0.73 <φ a / φ 1 <−0.56 (3)
条件(３)は、第１走査レンズ２１の第１面の曲率半径を規定し、ｆθレンズ全体の主走査断面パワーに対して、第１面がどの程度のパワーを負担するのが適当かを規定する。第２面のパワーは第１面が決まると自動的に決まるため、条件式には含まれていない。条件(３)の下限を下回ると、第１面のパワーが小さくなりすぎて(緩いメニスカス形状になりすぎて)、設計上の光学性能が悪くなり、上限を超えると、第１面のパワーが大きくなりすぎて（きついメニスカス形状になりすぎて）、製造誤差感度が高くなる。
続いて、上記の条件を満たす実施例を３例説明する。
Condition (3) defines the radius of curvature of the first surface of the first scanning lens 21 and determines how much power the first surface should bear relative to the main scanning cross-sectional power of the entire fθ lens. Stipulate. Since the power of the second surface is automatically determined when the first surface is determined, it is not included in the conditional expression. If the lower limit of the condition (3) is not reached, the power of the first surface becomes too small (becomes a loose meniscus shape) and the optical performance in design deteriorates. Too large (too tight meniscus shape), the manufacturing error sensitivity increases.
Next, three examples that satisfy the above conditions will be described.
実施例１の走査光学系の構成は、図１に示す通りである。実施例１においては、第１走査レンズ２１のポリゴンミラー１４側の第１面は凹の回転対称非球面、走査対象面３０側の第２面は凸の回転対称非球面、第２走査レンズ２２の第１面は凹の球面、第２面はアナモフィック非球面である。 The configuration of the scanning optical system of Example 1 is as shown in FIG. In the first embodiment, the first surface of the first scanning lens 21 on the polygon mirror 14 side is a concave rotationally symmetric aspherical surface, the second surface on the scanning target surface 30 side is a convex rotationally symmetric aspherical surface, and the second scanning lens 22. The first surface is a concave spherical surface, and the second surface is an anamorphic aspheric surface.
アナモフィック非球面は、光軸から離れた位置での副走査方向の曲率半径が主走査方向の断面形状とは無関係に設定された回転軸を持たない非球面であり、主走査方向の断面形状X(y)、 副走査方向の曲率半径ｒz(y)は、光軸上での主走査方向の曲率半径をry0、円錐係数をκ、主走査方向のｎ次の非球面係数をＡＭn、主走査方向の各位置yにおける光軸上での副走査方向の曲率半径をrz0、副走査方向のｎ次の非球面係数をＡＳnとして、それぞれ以下の式により求められる。 An anamorphic aspherical surface is an aspherical surface that does not have a rotation axis in which the radius of curvature in the sub-scanning direction at a position away from the optical axis is set independently of the cross-sectional shape in the main-scanning direction. (y), the radius of curvature rz (y) in the sub-scanning direction is the radius of curvature in the main scanning direction on the optical axis, ry 0 , the cone coefficient is κ, the n-th order aspherical coefficient in the main scanning direction is AM n , The radius of curvature in the sub-scanning direction on the optical axis at each position y in the main scanning direction is rz 0 , and the nth-order aspheric coefficient in the sub-scanning direction is AS n , respectively, and is obtained by the following equations.
実施例１にかかる走査光学系の具体的な数値構成を表３に示す。表３中の記号ｒyは各光学素子の主走査方向の曲率半径(単位：mm)、ｒzは副走査方向の曲率半径(回転対称面の場合には省略，単位：mm)、ｄは面間の光軸上の距離(単位：mm)、ｎλは設計波長での屈折率である。この例では、設計波長λは780nmである。 Table 3 shows specific numerical configurations of the scanning optical system according to the first example. The symbol ry in Table 3 is the radius of curvature of each optical element in the main scanning direction (unit: mm), rz is the radius of curvature in the sub-scanning direction (omitted for rotationally symmetric surfaces, unit: mm), and d is the distance between the surfaces. The distance on the optical axis (unit: mm), nλ is the refractive index at the design wavelength. In this example, the design wavelength λ is 780 nm.
第４面、第５面の回転対称非球面を定義する円錐係数、非球面係数の値を表４、表５、第７面のアナモフィック非球面を定義する円錐係数、非球面係数の値を表６にそれぞれ示す。 Table 4 and Table 5 show the values of the cone coefficient and aspheric coefficient defining the rotationally symmetric aspheric surfaces of the fourth surface and the fifth surface, and Tables 5 and 5 show the values of the cone coefficient and aspheric coefficient defining the anamorphic aspheric surface of the seventh surface. 6 respectively.
図４は、実施例１にかかる走査光学系の像面湾曲を示す。図４(Ａ)は設計上の像面湾曲、(Ｂ)は第１走査レンズ２１の第１面と第２面とが主走査方向に０．１ｍｍ相対的に偏心した際の像面湾曲、(Ｃ)は第１走査レンズ２１の第１面と第２面との屈折力がそれぞれ設計値から０．１dptr.変化した際の像面湾曲をそれぞれ示す。各図中、破線Ｍが主走査方向、実線Ｓが副走査方向の像面湾曲を示す。グラフの横軸は収差量(単位:mm)、縦軸は像高ｙ(単位:mm)を示している。収差量は、(Ａ)では±４．００mmの範囲、(Ｂ)、(Ｃ)では±１０．０mmの範囲で示されている。また、像高ｙは、光軸上を０とし、半導体レーザー１０が設けられている側をマイナス、反対側をプラスとして符号を付している。 FIG. 4 shows field curvature of the scanning optical system according to the first example. 4A is a designed field curvature, and FIG. 4B is a field curvature when the first surface and the second surface of the first scanning lens 21 are relatively decentered by 0.1 mm in the main scanning direction. (C) shows the curvature of field when the refractive powers of the first surface and the second surface of the first scanning lens 21 change by 0.1 dptr. From the design values, respectively. In each figure, the broken line M indicates the field curvature in the main scanning direction, and the solid line S indicates the field curvature in the sub-scanning direction. The horizontal axis of the graph represents the aberration amount (unit: mm), and the vertical axis represents the image height y (unit: mm). The aberration amount is shown in the range of ± 4.00 mm in (A), and in the range of ± 10.0 mm in (B) and (C). In addition, the image height y is denoted by 0 on the optical axis, minus the side where the semiconductor laser 10 is provided, and plus the opposite side.
実施例１の構成では、第１走査レンズ有効径20.76mm、主走査像面湾曲(設計値)1.28mm、偏心誤差感度2.81mm、屈折力誤差感度3.11mmである。 In the configuration of Example 1, the effective diameter of the first scanning lens is 20.76 mm, the main scanning field curvature (design value) is 1.28 mm, the eccentricity error sensitivity is 2.81 mm, and the refractive power error sensitivity is 3.11 mm.
実施例２の走査光学系の構成は、図１とほぼ同様であるため、図示は省略する。実施例２においては、第１走査レンズ２１の第１面は凹の回転対称非球面、第２面は凸の回転対称非球面、第２走査レンズ２２の第１面は凹の球面、第２面はアナモフィック非球面である。実施例２にかかる走査光学系の具体的な数値構成を表７に示す。 The configuration of the scanning optical system of Example 2 is substantially the same as that in FIG. In Example 2, the first surface of the first scanning lens 21 is a concave rotationally symmetric aspheric surface, the second surface is a convex rotationally symmetric aspheric surface, the first surface of the second scanning lens 22 is a concave spherical surface, The surface is an anamorphic aspheric surface. Table 7 shows specific numerical configurations of the scanning optical system according to the second example.
第４面、第５面の回転対称非球面を定義する円錐係数、非球面係数の値を表８、表９、第７面のアナモフィック非球面を定義する円錐係数、非球面係数の値を表１０にそれぞれ示す。 Tables 8 and 9 show the values of the conical coefficient and aspheric coefficient defining the rotationally symmetric aspheric surfaces of the fourth surface and the fifth surface, and Tables 8 and 9 show the values of the cone coefficient and aspheric coefficient defining the anamorphic aspheric surface of the seventh surface. 10 respectively.
図５は、実施例２にかかる走査光学系の像面湾曲を示す。(Ａ)、(Ｂ)、(Ｃ)の条件は図４の場合と同一である。実施例２の構成では、第１走査レンズ有効径20.60 mm、主走査像面湾曲(設計値)1.25mm、偏心誤差感度2.42mm、屈折力誤差感度2.75mmである。 FIG. 5 shows field curvature of the scanning optical system according to the second example. The conditions (A), (B), and (C) are the same as in FIG. In the configuration of Example 2, the effective diameter of the first scanning lens is 20.60 mm, the main scanning field curvature (design value) is 1.25 mm, the eccentricity error sensitivity is 2.42 mm, and the refractive power error sensitivity is 2.75 mm.
実施例３の走査光学系の構成は、図１とほぼ同様であるため、図示は省略する。実施例３においては、第１走査レンズ２１の第１面は凹の回転対称非球面、第２面は凸の回転対称非球面、第２走査レンズ２２の第１面は凹の球面、第２面はアナモフィック非球面である。実施例３にかかる走査光学系の具体的な数値構成を表１１に示す。 The configuration of the scanning optical system of Example 3 is substantially the same as that in FIG. In Example 3, the first surface of the first scanning lens 21 is a concave rotationally symmetric aspheric surface, the second surface is a convex rotationally symmetric aspheric surface, the first surface of the second scanning lens 22 is a concave spherical surface, The surface is an anamorphic aspheric surface. Table 11 shows specific numerical configurations of the scanning optical system according to the third example.
第４面、第５面の回転対称非球面を定義する円錐係数、非球面係数の値を表１２、表１３、第７面のアナモフィック非球面を定義する円錐係数、非球面係数の値を表１４にそれぞれ示す。 Tables 12 and 13 show the values of the cone coefficient and aspheric coefficient defining the rotationally symmetric aspheric surfaces of the fourth surface and the fifth surface, and Tables 13 and 13 show the values of the cone coefficient and aspheric coefficient defining the anamorphic aspheric surface of the seventh surface. 14 respectively.
図６は、実施例３にかかる走査光学系の像面湾曲を示す。(Ａ)、(Ｂ)、(Ｃ)の条件は図４の場合と同一である。実施例３の構成では、第１走査レンズ有効径20.84mm、主走査像面湾曲(設計値)1.32mm、偏心誤差感度2.65mm、屈折力誤差感度2.63mmである。 FIG. 6 shows field curvature of the scanning optical system according to the third example. The conditions (A), (B), and (C) are the same as in FIG. In the configuration of Example 3, the effective diameter of the first scanning lens is 20.84 mm, the main scanning field curvature (design value) is 1.32 mm, the eccentric error sensitivity is 2.65 mm, and the refractive power error sensitivity is 2.63 mm.
次に、上記の実施例との性能の比較のため、２つの比較例を説明する。比較例１は、実施例と同一の焦点距離、走査幅を持つが、第１走査レンズとポリゴンミラーとの距離が長く、ｆθレンズが実施例と比較して大型の例、比較例２は、製造誤差感度を考慮せずに設計上の光学性能を良好にするようにして比較例１を小型化した例である。 Next, two comparative examples will be described in order to compare the performance with the above-described embodiment. Comparative Example 1 has the same focal length and scanning width as the Example, but the distance between the first scanning lens and the polygon mirror is long, and the fθ lens is larger than the Example, Comparative Example 2 is This is an example in which the comparative example 1 is miniaturized so as to improve the designed optical performance without considering the manufacturing error sensitivity.
［比較例１］
図７は、比較例１の構成を示す主走査面内の説明図である。光学素子の並びは図１に示す実施形態と同一であるため、同一の符号を付して重複した説明は省略する。比較例１においては、第１走査レンズ２１の第１面は凹の球面、第２面は凸の回転対称非球面、第２走査レンズ２２の第１面は凹の球面、第２面はアナモフィック非球面である。比較例１の具体的な数値構成は、以下の表１５に示されている。
[Comparative Example 1]
FIG. 7 is an explanatory diagram in the main scanning plane showing the configuration of the first comparative example. Since the arrangement of the optical elements is the same as that of the embodiment shown in FIG. 1, the same reference numerals are given and the repeated description is omitted. In Comparative Example 1, the first surface of the first scanning lens 21 is a concave spherical surface, the second surface is a convex rotationally symmetric aspheric surface, the first surface of the second scanning lens 22 is a concave spherical surface, and the second surface is an anamorphic. It is aspheric. The specific numerical configuration of Comparative Example 1 is shown in Table 15 below.
第５面の回転対称非球面を定義する円錐係数、非球面係数の値を表１６、第７面のアナモフィック非球面を定義する円錐係数、非球面係数の値を表１７にそれぞれ示す。 Table 16 shows the values of the cone coefficient and aspheric coefficient defining the rotationally symmetric aspheric surface of the fifth surface, and Table 17 shows the values of the cone coefficient and aspheric coefficient defining the anamorphic aspheric surface of the seventh surface.
図８は、比較例１にかかる走査光学系の像面湾曲を示す。(Ａ)、(Ｂ)、(Ｃ)の条件は図４の場合と同一である。比較例１の構成では、第１走査レンズ有効径31.56mm、主走査像面湾曲(設計値)0.97mm、偏心誤差感度0.04mm、屈折力誤差感度0.86mmである。 FIG. 8 shows field curvature of the scanning optical system according to the first comparative example. The conditions (A), (B), and (C) are the same as in FIG. In the configuration of Comparative Example 1, the effective diameter of the first scanning lens is 31.56 mm, the main scanning field curvature (design value) is 0.97 mm, the eccentricity error sensitivity is 0.04 mm, and the refractive power error sensitivity is 0.86 mm.
［比較例２］
図９は、比較例２の構成を示す主走査面内の説明図である。光学素子の並びは図１に示す実施形態と同一であるため、同一の符号を付して重複した説明は省略する。比較例２においては、第１走査レンズ２１の第１面は凹の回転対称非球面、第２面は凸の回転対称非球面、第２走査レンズ２２の第１面は凹の球面、第２面はアナモフィック非球面である。比較例２の具体的な数値構成は、以下の表１８に示されている。
[Comparative Example 2]
FIG. 9 is an explanatory diagram in the main scanning plane showing the configuration of the second comparative example. Since the arrangement of the optical elements is the same as that of the embodiment shown in FIG. 1, the same reference numerals are given and the repeated description is omitted. In Comparative Example 2, the first surface of the first scanning lens 21 is a concave rotationally symmetric aspheric surface, the second surface is a convex rotationally symmetric aspheric surface, the first surface of the second scanning lens 22 is a concave spherical surface, The surface is an anamorphic aspheric surface. The specific numerical configuration of Comparative Example 2 is shown in Table 18 below.
第４面、第５面の回転対称非球面を定義する円錐係数、非球面係数の値を表１９、表２０、第７面のアナモフィック非球面を定義する円錐係数、非球面係数の値を表２１にそれぞれ示す。 Table 19 and Table 20 show the values of the conical coefficient and aspheric coefficient defining the rotationally symmetric aspheric surfaces of the fourth surface and the fifth surface, and Tables 19 and 20 show the values of the cone coefficient and aspheric coefficient defining the anamorphic aspheric surface of the seventh surface. 21 respectively.
図１０は、比較例２にかかる走査光学系の像面湾曲を示す。(Ａ)、(Ｂ)、(Ｃ)の条件は図４の場合と同一である。比較例２の構成では、第１走査レンズ有効径20.91mm、主走査像面湾曲(設計値)1.26
mm、偏心誤差感度4.00mm、屈折力誤差感度4.51mmである。
FIG. 10 shows the curvature of field of the scanning optical system according to the second comparative example. The conditions (A), (B), and (C) are the same as in FIG. In the configuration of Comparative Example 2, the effective diameter of the first scanning lens is 20.91 mm, and the main scanning field curvature (design value) is 1.26.
mm, eccentric error sensitivity 4.00 mm, refractive power error sensitivity 4.51 mm.
次に、上記の実施例及び比較例と、本発明の条件(１)、(２)、(３)との関係について説明する。表２２は、条件(１)「θＬ＜０．１５Ｗ」に関する各実施例、比較例の数値を示す。条件(１)の欄は、○が条件を満たすこと、×は満たさないことを表す。小型化された実施例１〜３及び比較例２は条件(１)を満たすが、比較例１は満たさず、ｆθレンズが大型である。 Next, the relationship between the above examples and comparative examples and the conditions (1), (2), and (3) of the present invention will be described. Table 22 shows numerical values of the respective examples and comparative examples regarding the condition (1) “θL <0.15W”. The column of the condition (1) indicates that ○ satisfies the condition and × does not satisfy it. Although the miniaturized Examples 1 to 3 and Comparative Example 2 satisfy the condition (1), Comparative Example 1 is not satisfied, and the fθ lens is large.
また、表２３は、条件(２)「−０．９＜ΔＣ／Ｃ＜−０．６」に関する各実施例、比較例の数値である。実施例１〜３は、小型化しつつ光学性能と製造誤差感度とを考慮して設計されているため、第１面、第２面共に条件(２)を満たしている。比較例１の第１面は球面であり、第２面は非球面量が小さく、共に条件(２)を満たさない。比較例１は小型化されていないため、非球面量が少なくとも良好な光学性能が得られる。比較例２は、小型化しつつ設計上の光学性能を良好に保つため、非球面量が大きく設計されており、第１面、第２面共に条件(２)を満たさない。 Table 23 shows numerical values of Examples and Comparative Examples regarding the condition (2) “−0.9 <ΔC / C <−0.6”. Since the first to third embodiments are designed in consideration of optical performance and manufacturing error sensitivity while being downsized, both the first surface and the second surface satisfy the condition (2). The first surface of Comparative Example 1 is a spherical surface, and the second surface has a small amount of aspheric surface, and both do not satisfy the condition (2). Since Comparative Example 1 is not miniaturized, an optical performance with at least an aspheric amount can be obtained. Comparative Example 2 is designed to have a large amount of aspherical surface in order to keep the designed optical performance good while downsizing, and neither the first surface nor the second surface satisfies the condition (2).
さらに、表２４は、条件(３)「−０．７３＜φa／φ1＜−０．５６」に関する各実施例、比較例の数値である。小型化された実施例１〜３及び比較例２は条件(１)を満たすが、比較例１は満たしていない。 Further, Table 24 shows numerical values of the respective examples and comparative examples regarding the condition (3) “−0.73 <φa / φ1 <−0.56”. Although the miniaturized Examples 1 to 3 and Comparative Example 2 satisfy the condition (1), Comparative Example 1 does not satisfy the condition (1).
上記のように、実施例１〜３は、いずれも条件(１)、(２)、(３)を満たすため、ｆθレンズの小型化を図りつつ、光学性能と製造誤差感度とのバランスをとり、必要な光学性能を確保しつつ、製造の容易な走査光学系を提供することができる。これに対して、比較例１はｆθレンズが大型であり、走査光学系全体のサイズをコンパクトにすることができない。一方、比較例２は、小型化は達成されているものの、製造誤差感度を考慮せずに設計されているため、設計上の光学性能は高いが、製造誤差感度が高く、製造が困難である。 As described above, each of Examples 1 to 3 satisfies the conditions (1), (2), and (3). Therefore, the fθ lens is reduced in size and the optical performance and the manufacturing error sensitivity are balanced. It is possible to provide a scanning optical system that is easy to manufacture while ensuring the necessary optical performance. On the other hand, in Comparative Example 1, the fθ lens is large, and the size of the entire scanning optical system cannot be made compact. On the other hand, although the comparative example 2 has been reduced in size, it is designed without considering the manufacturing error sensitivity. Therefore, the optical performance in design is high, but the manufacturing error sensitivity is high and the manufacturing is difficult. .
１０ 半導体レーザー
１４ ポリゴンミラー
２０ ｆθレンズ
２１ 第１レンズ
２２ 第２レンズ
３０ 走査対象面
DESCRIPTION OF SYMBOLS 10 Semiconductor laser 14 Polygon mirror 20 f (theta) lens 21 1st lens 22 2nd lens 30 Scan object surface
Claims (2)
前記光源部から発する光束を偏向させる偏向器と、
前記偏向器により偏向された光束を被走査面上で主走査方向に走査するスポットとして収束させる結像光学系とを備え、
前記結像光学系は、単数または複数の単レンズから構成され、そのうち最も前記偏向器に近い位置にある第１走査レンズの少なくとも一面は非球面であり、前記偏向器の偏向面から前記第１走査レンズまでの距離をＬ[mm]、前記結像光学系の半画角をθ[rad.]、走査幅（半幅）をＷ[mm]、前記第１走査レンズの非球面の光軸上の曲率をＣ、主走査方向の有効走査領域内における曲率の最大値と最小値との差をΔＣとし、前記結像光学系の主走査断面における屈折力をφ ａ [dptr.]、前記第１走査レンズの第１面の屈折力をφ １ [dptr.]としたとき、以下の条件(１)、(２)、(３)を満たすことを特徴とする走査光学系。
θＬ＜０．１５Ｗ …(１)
−０．９＜ΔＣ／Ｃ＜−０．６ …(２)
−０．７３＜φ ａ ／φ １ ≦−０．６２ …(３) A light source that generates a luminous flux;
A deflector for deflecting a light beam emitted from the light source unit;
An imaging optical system that converges the light beam deflected by the deflector as a spot scanned in the main scanning direction on the surface to be scanned;
The imaging optical system includes a single lens or a plurality of single lenses, of which at least one surface of the first scanning lens located closest to the deflector is an aspherical surface, and the first scanning lens has a first surface from the deflecting surface of the deflector. The distance to the scanning lens is L [mm], the half angle of view of the imaging optical system is θ [rad.], The scanning width (half width) is W [mm], on the optical axis of the aspherical surface of the first scanning lens , C is the curvature, and ΔC is the difference between the maximum value and the minimum value of the curvature in the effective scanning region in the main scanning direction, and the refractive power in the main scanning section of the imaging optical system is φ a [dptr.], A scanning optical system satisfying the following conditions (1), (2 ), and (3) when the refractive power of the first surface of the first scanning lens is φ 1 [dptr.]:
θL <0.15W (1)
−0.9 <ΔC / C <−0.6 (2)
−0.73 <φ a / φ 1 ≦ −0.62 (3)
前記結像光学系のうち最も前記偏向器側に配置される第１走査レンズの少なくとも一面を非球面とし、前記偏向器の偏向面から前記第１走査レンズまでの距離をＬ[mm]、前記結像光学系の半画角をθ[rad.]、走査幅（半幅）をＷ[mm] 、前記第１走査レンズの非球面
の光軸上の曲率をＣ、主走査方向の有効走査領域内における曲率の最大値と最小値との差をΔＣとし、前記結像光学系の主走査断面における屈折力をφ ａ [dptr.]、前記第１走査
レンズの第１面の屈折力をφ １ [dptr.]としたとき、以下の条件(１)、(２)、（３）を満
たすよう設計することを特徴とする走査光学系の設計方法。
θＬ＜０．１５Ｗ …(１)
−０．９＜ΔＣ／Ｃ＜−０．６ …(２)
−０．７３＜φ ａ ／φ １ ≦−０．６２ …(３) In a design method of a scanning optical system for converging a light beam emitted from a light source unit and deflected by a deflector as a spot scanned in a main scanning direction on a scanned surface by an imaging optical system,
At least one surface of the first scanning lens arranged closest to the deflector in the imaging optical system is an aspherical surface, and the distance from the deflection surface of the deflector to the first scanning lens is L [mm], The half angle of view of the imaging optical system is θ [rad.], The scanning width (half width) is W [mm], and the aspherical surface of the first scanning lens
C is the curvature on the optical axis, ΔC is the difference between the maximum value and the minimum value of the curvature in the effective scanning region in the main scanning direction, and the refractive power in the main scanning section of the imaging optical system is φ a [dptr. ], The first scan
When the refractive power of the first surface of the lens is φ 1 [dptr.], The following conditions (1), (2) and (3) are satisfied.
A design method of a scanning optical system, characterized by being designed to add.
θL <0.15W (1)
−0.9 <ΔC / C <−0.6 (2)
−0.73 <φ a / φ 1 ≦ −0.62 (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005165469A JP4654072B2 (en) | 2005-06-06 | 2005-06-06 | Scanning optical system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005165469A JP4654072B2 (en) | 2005-06-06 | 2005-06-06 | Scanning optical system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2006337916A JP2006337916A (en) | 2006-12-14 |
| JP4654072B2 true JP4654072B2 (en) | 2011-03-16 |
Family
ID=37558507
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2005165469A Expired - Fee Related JP4654072B2 (en) | 2005-06-06 | 2005-06-06 | Scanning optical system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4654072B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5034722B2 (en) | 2007-07-05 | 2012-09-26 | コニカミノルタアドバンストレイヤー株式会社 | Scanning optical system, optical scanning device, and image forming apparatus |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001194611A (en) * | 1999-10-29 | 2001-07-19 | Canon Inc | Optical scanner, multi-beam optical scanner, and image forming device |
| JP2001296491A (en) * | 2000-04-13 | 2001-10-26 | Canon Inc | Optical scanner and image forming device using the same |
| JP2001343602A (en) * | 2000-03-29 | 2001-12-14 | Canon Inc | Optical scanning optical system and image forming device using the same |
| JP2002048993A (en) * | 2000-05-25 | 2002-02-15 | Canon Inc | Optical scanner and image forming device using the same |
| JP2003005117A (en) * | 2001-06-27 | 2003-01-08 | Canon Inc | Optical scanner, multibeam scanner and image forming device using the same |
| JP2003156703A (en) * | 2001-11-21 | 2003-05-30 | Canon Inc | Optical scanner and image forming device using the same |
| JP2004184655A (en) * | 2002-12-03 | 2004-07-02 | Canon Inc | Optical scanner and image forming apparatus using same |
-
2005
- 2005-06-06 JP JP2005165469A patent/JP4654072B2/en not_active Expired - Fee Related
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001194611A (en) * | 1999-10-29 | 2001-07-19 | Canon Inc | Optical scanner, multi-beam optical scanner, and image forming device |
| JP2001343602A (en) * | 2000-03-29 | 2001-12-14 | Canon Inc | Optical scanning optical system and image forming device using the same |
| JP2001296491A (en) * | 2000-04-13 | 2001-10-26 | Canon Inc | Optical scanner and image forming device using the same |
| JP2002048993A (en) * | 2000-05-25 | 2002-02-15 | Canon Inc | Optical scanner and image forming device using the same |
| JP2003005117A (en) * | 2001-06-27 | 2003-01-08 | Canon Inc | Optical scanner, multibeam scanner and image forming device using the same |
| JP2003156703A (en) * | 2001-11-21 | 2003-05-30 | Canon Inc | Optical scanner and image forming device using the same |
| JP2004184655A (en) * | 2002-12-03 | 2004-07-02 | Canon Inc | Optical scanner and image forming apparatus using same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2006337916A (en) | 2006-12-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6104522A (en) | Optical scanning apparatus with controlled sag and ghost | |
| US6067106A (en) | Scanning optical apparatus | |
| US7375869B2 (en) | Tandem type scanning optical system | |
| JP3397638B2 (en) | Optical scanning optical system and image forming apparatus using the same | |
| US6697183B2 (en) | Light beam scanning apparatus and image forming system incorporating such apparatus | |
| JP3559711B2 (en) | Scanning optical device and multi-beam scanning optical device | |
| JP4293780B2 (en) | Scanning optical system | |
| JP4654072B2 (en) | Scanning optical system | |
| JP2000081584A (en) | Scanning optical device | |
| JP2000267030A (en) | Optical scanning device | |
| JPH08240768A (en) | Scanning optical system | |
| JP3576817B2 (en) | Scanning optical device | |
| JP3554157B2 (en) | Optical scanning optical system and laser beam printer | |
| JP2003227998A (en) | Scanning optical system | |
| JP3548476B2 (en) | Scanning optical system | |
| JP3804886B2 (en) | Imaging optical system for optical scanning device | |
| JP4293952B2 (en) | Scanning lens | |
| JP2017090592A (en) | Optical scanning device | |
| JP3728256B2 (en) | Scanning optical device | |
| JP4072559B2 (en) | Scanning optical device | |
| JP3548499B2 (en) | Scanning optical system | |
| JP2023012296A (en) | Optical scanner and image forming apparatus including the same | |
| JP4652506B2 (en) | Scanning optical device | |
| JP3725182B2 (en) | Optical scanning device | |
| JP2006220718A (en) | Scanning optical system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20080313 |
|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A712 Effective date: 20080501 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20100830 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20100907 |
|
| RD03 | Notification of appointment of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7423 Effective date: 20101105 |
|
| RD04 | Notification of resignation of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7424 Effective date: 20101105 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20101108 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20101207 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20101220 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 4654072 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20131224 Year of fee payment: 3 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313111 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313111 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| LAPS | Cancellation because of no payment of annual fees |