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WO2013008832A1 - Light-guiding optical assembly and scan image forming device - Google Patents

Light-guiding optical assembly and scan image forming device Download PDF

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Publication number
WO2013008832A1
WO2013008832A1 PCT/JP2012/067656 JP2012067656W WO2013008832A1 WO 2013008832 A1 WO2013008832 A1 WO 2013008832A1 JP 2012067656 W JP2012067656 W JP 2012067656W WO 2013008832 A1 WO2013008832 A1 WO 2013008832A1
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Prior art keywords
optical system
light
lens
light guide
scanning
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PCT/JP2012/067656
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French (fr)
Japanese (ja)
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棚橋大輔
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コニカミノルタアドバンストレイヤー株式会社
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Publication of WO2013008832A1 publication Critical patent/WO2013008832A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/12—Scanning systems using multifaceted mirrors
    • G02B26/124—Details of the optical system between the light source and the polygonal mirror
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
    • B41J2/47—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using the combination of scanning and modulation of light
    • B41J2/471—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using the combination of scanning and modulation of light using dot sequential main scanning by means of a light deflector, e.g. a rotating polygonal mirror
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/113—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using oscillating or rotating mirrors
    • H04N1/1135—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using oscillating or rotating mirrors for the main-scan only

Definitions

  • the present invention relates to a light guide optical system that guides light from a light source to a deflecting optical element, particularly a diffractive lens, in a scanning imaging apparatus used in an LBP (laser beam printer), a copying machine, a multifunction machine, and the like.
  • the present invention relates to an optical optical system and a scanning imaging apparatus.
  • a light beam modulated and emitted from a light source according to an image signal is periodically generated by a deflecting optical element made of, for example, a rotating polygon mirror (polygon mirror)
  • the image is recorded by optically scanning the surface of the photosensitive recording medium (photosensitive drum) that is deflected and focused on a photosensitive recording medium (photosensitive drum) surface by a scanning optical element having f ⁇ characteristics.
  • a scanning image forming apparatus used in such a laser beam printer or the like includes a light guide optical system that guides light from a light source to a deflecting optical element, and a scan that images light deflected by the deflecting optical element on an image plane.
  • the conventional light guiding optical system includes a collimating lens that converts light from a light source into parallel light, and a cylindrical lens that converts the parallel light into a line image on the reflecting surface of the deflecting optical element.
  • glass is mainly used as the lens material used for these lenses.
  • glass-molded aspherical lenses have been used for collimating lenses installed in the vicinity of the light source because they are required to have environmental resistance against environmental fluctuations such as temperature rise and the ability to correct aberrations satisfactorily. There is a real situation.
  • the glass molded aspherical lens has good environmental resistance but is expensive, and uses two lenses for the light guide optical system, which is a factor that increases the cost of the scanning imaging device.
  • an inexpensive collimating lens excellent in environmental resistance characteristics has been proposed by using a resin lens as a collimating lens and adding a diffraction structure (see Patent Documents 1 and 2).
  • a resin-made light guide lens in which the functions of a collimating lens and a cylindrical lens, which have been conventionally separated, are realized with one single lens has been proposed (see Patent Document 3).
  • Patent Documents 1 and 2 there is no specific example regarding the surface to which the diffractive structure is added, and it is difficult to say that aberrations can be corrected satisfactorily even with a lens having excellent environmental resistance. Furthermore, in Patent Document 3, a cylindrical lens is provided with a diffractive surface, but there is a problem that the number of parts increases and assembly is difficult.
  • the present invention has been made in view of the above-mentioned problems, and provides a light guide optical system capable of excellent correction of aberration and excellent aberration resistance while being low in cost, and a scanning imaging apparatus using the same. For the purpose.
  • the light guide optical system according to claim 1 is a light guide optical system that guides light emitted from a light source to a deflecting optical element, and scanning optical that forms an image on the image plane of the light deflected by the deflecting optical element.
  • a light guide optical system used in a scanning imaging apparatus that optically scans the image plane The light guide optical system is composed of a single resin lens, and the lens has an anamorphic surface shape in which one surface facing the optical axis direction has different powers in the main scanning direction and the sub scanning direction, and The other surface has a rotationally symmetric diffraction structure.
  • a light guiding optical system that uses two lenses to convert light emitted from a light source into a beam shape suitable for each of the main scanning direction and the sub scanning direction is used in each of the main scanning direction and the sub scanning direction.
  • anamorphic surfaces with different powers it is composed of only a single lens, and by this, a light guiding optical system is composed of a single lens, thereby realizing cost reduction.
  • a rotationally symmetric diffractive structure on a surface different from the anamorphic surface of the lens a light guiding optical system that has excellent environmental resistance characteristics and can correct aberrations well is realized.
  • One surface may face the light source side or the deflection optical element side.
  • the light guiding optical system according to claim 2 is characterized in that, in the invention according to claim 1, the other surface of the lens is a spherical surface.
  • a diffractive structure is provided with one surface of the lens as a flat surface, it is necessary to use the power of diffraction for correcting the defocus when the environment changes, so aberration correction, particularly off-axis characteristics (coma aberration correction) is performed. It was difficult.
  • the diffractive structure is provided on the aspherical surface of the lens, the error sensitivity of the lens increases and the difficulty of assembly increases.
  • one surface has an anamorphic surface shape, if the other surface is an aspheric surface, it becomes very difficult to manufacture the optical surfaces facing each other without decentration.
  • the surface to which the diffractive structure is added a simple spherical surface, it is possible to effectively correct aberrations without increasing the decentration error sensitivity of the surface, and one surface is anamorphic. It was also found that a lens that is easy to manufacture can be obtained.
  • the power can be dispersed on both surfaces of the lens, and the diffractive power can be used to correct focus fluctuations due to environmental changes, and the sine condition can be corrected well.
  • the light guiding optical system according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the other surface of the lens is provided on the light source side.
  • the light guiding optical system according to a fourth aspect of the invention is characterized in that, in the invention according to any one of the first to third aspects, the lens can be driven in an optical axis direction by an actuator.
  • the light guiding optical system according to claim 5 is characterized in that, in the invention according to any one of claims 1 to 4, the lens has a meniscus shape having a concave on the light source side.
  • a light guiding optical system is characterized in that, in the invention according to any one of the first to fifth aspects, the diffractive structure has a blaze shape.
  • the blaze shape means that the cross-sectional shape including the optical axis of the lens is a sawtooth shape.
  • a scanning image forming apparatus includes the light guide optical system according to any one of the first to sixth aspects.
  • the present invention it is possible to provide a light guide optical system that is low in cost and excellent in environmental resistance characteristics and that can correct aberrations well, and a scanning imaging apparatus using the same.
  • FIG. 1 It is a figure which shows the main scanning direction cross section of a scanning imaging device. It is sectional drawing of a light guide optical system.
  • (A) is a cross section in the sub-scanning direction (xy cross section) according to the first embodiment, and (b) is a cross section in the main scanning direction (zx cross section) according to the first embodiment.
  • FIG. 1 shows a main surface on a surface on which a light beam is incident in the scanning optical system, where the optical axis (also referred to as main scanning optical axis) of the scanning optical system is the z axis, the main scanning direction is the x axis, and the sub scanning direction is the y axis.
  • FIG. 2 is an enlarged view of the light guide optical system shown in FIG.
  • a scanning imaging apparatus SF is incorporated in an image forming apparatus (not shown), and is emitted from a light source LD that is a semiconductor laser, a deflection optical element PM such as a polygon mirror, and a light source LD.
  • a light guide optical system IOS that guides the reflected light to the deflection optical element PM
  • a scanning optical system SOS that scans the light deflected by the deflection optical element PM and forms an image on the image plane.
  • the light guide optical system IOS is composed of a single collimating lens CL that is a resin lens, and the collimating lens CL has a surface S2 on the deflection optical element PM side that has different powers in the main scanning direction and the sub-scanning direction. It has an anamorphic surface shape, and the surface S1 on the light source LD side has a rotationally symmetric diffraction structure.
  • the surface S1 on the light source LD side is preferably a spherical surface.
  • the absolute value of the radius of curvature of the surface S1 is preferably larger than the surface S2 (the paraxial refractive power of the surface S1 is smaller than the surface S2).
  • An aperture stop AP is provided in the vicinity of the surface S2.
  • the natural convergence point in the main scanning direction is preferably located at a position 250 mm or more away from the exit surface of the collimating lens CL.
  • the correction (environmental fluctuation) due to the refractive index change of the resin material due to the temperature change is designed to suppress the focus fluctuation in the main scanning direction.
  • an actuator AC that drives the collimating lens CL in the optical axis direction may be provided to provide a focusing function, thereby correcting the focus shift.
  • a light beam B emitted from a light source LD passes through a light guide optical system IOS, that is, a collimator lens CL, passes through an aperture stop AP, is reflected by a deflecting reflection surface of the deflecting optical element PM, and passes through the scanning optical system.
  • the light passes through the first scanning imaging lens L1 and the second scanning imaging lens L2 and forms an image on the scanned surface DP.
  • the deflection reflection surface is tilted, so that the light beam B is scanned in the main scanning direction at least in the range of the lens effective diameter L in the main scanning direction. Scanning can be performed to form an image.
  • the surface S2 of the single collimating lens CL can be converted into a beam shape suitable for each of the main scanning direction and the sub-scanning direction, and excellent environmental resistance characteristics can be obtained by the diffraction structure of the surface S1. It can be secured and aberrations can be corrected well.
  • a collimating lens which is an example suitable for the embodiment of the present invention will be described.
  • a power of 10 for example, 2.5 ⁇ 10 ⁇ 3
  • E for example, 2.5 ⁇ E ⁇ 3
  • the surface shape is defined by the following formula using a local orthogonal coordinate system (x, y, z) with the surface vertex as the origin based on the numerical values in the table. It is a free-form surface.
  • optical path difference given to the light flux of each wavelength by the diffractive structure of the lens is defined by a mathematical formula obtained by substituting the coefficient shown in the table into the optical path difference function of Formula 2.
  • ⁇ wavelength used
  • m diffraction order
  • ⁇ B normalized wavelength
  • h distance in the direction perpendicular to the optical axis from the optical axis.
  • the coefficient C1 of the diffractive surface is ⁇ 0.015 ⁇ C1 ⁇ ⁇ 0.007, as shown in each table.
  • Example 1 shows lens data of Example 1.
  • FIG. 3A is a cross section in the sub-scanning direction (xy cross section) according to the first embodiment
  • FIG. 3B is a cross section in the main scanning direction (zx cross section) according to the first embodiment.
  • the incident surface S1 of the resin collimating lens having a concave meniscus shape is a spherical surface, in which an annular blazed diffractive structure centering on the optical axis is formed
  • the exit surface S2 is an anamorphic surface.
  • the diffraction power ⁇ 1 at the diffraction surface S1 and the refraction power ⁇ 2 at the diffraction surface S1 of the lens satisfy the following equations. ⁇ 1> 0.01, ⁇ 2 ⁇ 0,
  • Example 2 shows lens data of Example 2.
  • the cross-sectional view of Example 2 is the same as FIG.
  • the incident surface S1 of the resin collimating lens having a concave meniscus shape is a spherical surface, in which an annular blazed diffractive structure centering on the optical axis is formed, and the exit surface S2 is an anamorphic surface.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Facsimile Scanning Arrangements (AREA)

Abstract

Provided are a light-guiding optical assembly with superior environmental resilience and with which good correction of astigmatism is possible while being inexpensive, and a scan image forming device employing same. A light-guiding optical assembly (IOS) is formed from a single collimating lens (CL) which is a resin lens. A surface (S2) of a polarizing optical element (PM) side of the collimating lens (CL) has an anamorphic surface shape wherein power varies in the forward scan direction and the reverse scan direction, and a surface (S1) of a light source (LD) side of the collimating lens (CL) has a rotationally symmetric diffraction structure.

Description

導光光学系及び走査結像装置Light guiding optical system and scanning imaging apparatus
　本発明は、LBP（レーザービームプリンタ）及び複写機、複合機などに使用される走査結像装置において、光源からの光を偏向光学素子に導光する導光光学系、特に回折レンズを含む導光光学系及び走査結像装置に関する。 The present invention relates to a light guide optical system that guides light from a light source to a deflecting optical element, particularly a diffractive lens, in a scanning imaging apparatus used in an LBP (laser beam printer), a copying machine, a multifunction machine, and the like. The present invention relates to an optical optical system and a scanning imaging apparatus.
　従来よりレーザービームプリンタやデジタル複写機等に用いられる走査結像装置においては、画像信号に応じて光源から光変調され放射した光束を、例えば回転多面鏡（ポリゴンミラー）より成る偏向光学素子により周期的に偏向させ、ｆθ特性を有する走査光学素子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集束させ、その面上を光走査して画像記録を行っている。 2. Description of the Related Art Conventionally, in a scanning image forming apparatus used in a laser beam printer, a digital copying machine or the like, a light beam modulated and emitted from a light source according to an image signal is periodically generated by a deflecting optical element made of, for example, a rotating polygon mirror (polygon mirror) The image is recorded by optically scanning the surface of the photosensitive recording medium (photosensitive drum) that is deflected and focused on a photosensitive recording medium (photosensitive drum) surface by a scanning optical element having fθ characteristics.
　このようなレーザービームプリンタ等に用いられる走査結像装置は、光源からの光を偏向光学素子に導光する導光光学系と、偏向光学素子により偏向された光を像面に結像する走査光学系とを含んでいるが、走査結像装置の一層の低価格化、軽量化促進等が望まれている。ここで、従来の導光光学系は、光源からの光を平行光に変換するコリメートレンズと、前記平行光を偏向光学素子の反射面において線像に変換するためのシリンドリカルレンズとを含むのが一般的である。しかるに、これらのレンズに用いられるレンズ材料は主にガラスが使用されている。特に、光源近傍に設置されるコリメートレンズには、温度上昇などの環境変動への耐環境特性と収差を良好に補正する性能とが求められることから、ガラスモールド非球面レンズが使用されてきたという実情がある。 A scanning image forming apparatus used in such a laser beam printer or the like includes a light guide optical system that guides light from a light source to a deflecting optical element, and a scan that images light deflected by the deflecting optical element on an image plane. However, it is desired to further reduce the price and promote the weight reduction of the scanning image forming apparatus. Here, the conventional light guiding optical system includes a collimating lens that converts light from a light source into parallel light, and a cylindrical lens that converts the parallel light into a line image on the reflecting surface of the deflecting optical element. It is common. However, glass is mainly used as the lens material used for these lenses. In particular, glass-molded aspherical lenses have been used for collimating lenses installed in the vicinity of the light source because they are required to have environmental resistance against environmental fluctuations such as temperature rise and the ability to correct aberrations satisfactorily. There is a real situation.
　しかし、ガラスモールド非球面レンズは、耐環境特性は良いがコスト高であり、しかも導光光学系にレンズを二枚用いており、これが走査結像装置のコストを押し上げる要因であった。これに対し、コリメートレンズに樹脂レンズを用い、回折構造を付加することで、耐環境特性に優れた安価なコリメートレンズが提案されている（特許文献１，２参照）。また、従来分かれていたコリメートレンズの機能と、シリンドリカルレンズの機能とを、１枚の単玉レンズで実現した樹脂製導光レンズも提案されている（特許文献３参照）。 However, the glass molded aspherical lens has good environmental resistance but is expensive, and uses two lenses for the light guide optical system, which is a factor that increases the cost of the scanning imaging device. On the other hand, an inexpensive collimating lens excellent in environmental resistance characteristics has been proposed by using a resin lens as a collimating lens and adding a diffraction structure (see Patent Documents 1 and 2). In addition, a resin-made light guide lens in which the functions of a collimating lens and a cylindrical lens, which have been conventionally separated, are realized with one single lens has been proposed (see Patent Document 3).
特許第３４３２０８５号明細書Japanese Patent No. 3432085 特開２００３－３３７２９５号公報JP 2003-337295 A 特開２００７－１１１１３号公報JP 2007-11113 A
　しかしながら、特許文献１，２では、回折構造を付加する面に関する具体的な実施例が無く、また例え耐環境特性に優れたレンズであっても、収差を良好に補正できるとは言い難い。更に、特許文献３では、シリンドリカルレンズに回折面を設けているが、部品点数が多くなり組み立てが困難であるという課題があった。 However, in Patent Documents 1 and 2, there is no specific example regarding the surface to which the diffractive structure is added, and it is difficult to say that aberrations can be corrected satisfactorily even with a lens having excellent environmental resistance. Furthermore, in Patent Document 3, a cylindrical lens is provided with a diffractive surface, but there is a problem that the number of parts increases and assembly is difficult.
　本発明は、上述の問題に鑑みてなされたものであり、低コストでありながらも、耐環境特性に優れ収差も良好に補正できる導光光学系及びそれを用いた走査結像装置を提供することを目的とする。 The present invention has been made in view of the above-mentioned problems, and provides a light guide optical system capable of excellent correction of aberration and excellent aberration resistance while being low in cost, and a scanning imaging apparatus using the same. For the purpose.
　請求項１に記載の導光光学系は、光源から出射された光を偏向光学素子へ導光する導光光学系と、前記偏向光学素子により偏向された光を像面に結像する走査光学系とを有し、前記像面を光走査する走査結像装置に用いる導光光学系において、
　前記導光光学系は単一の樹脂レンズからなり、前記レンズは、光軸方向を向いた一方の面が主走査方向と副走査方向とでパワーが異なるアナモルフィックな面形状であり、且つ他方の面が、回転対称な回折構造を有することを特徴とする。 The light guide optical system according to claim 1 is a light guide optical system that guides light emitted from a light source to a deflecting optical element, and scanning optical that forms an image on the image plane of the light deflected by the deflecting optical element. A light guide optical system used in a scanning imaging apparatus that optically scans the image plane,
The light guide optical system is composed of a single resin lens, and the lens has an anamorphic surface shape in which one surface facing the optical axis direction has different powers in the main scanning direction and the sub scanning direction, and The other surface has a rotationally symmetric diffraction structure.
　従来技術では、二枚のレンズを用いて光源から出射された光を主走査方向、副走査方向それぞれに適したビーム形状に変換していた導光光学系を、主走査、副走査方向それぞれでパワーが異なるアナモルフィックな面を用いることで単一のレンズのみで構成し、これにより単一のレンズにより導光光学系を構成して、低コスト化を実現した。さらに、レンズのアナモルフィックな面とは別な面には、回転対称な回折構造を有することで、耐環境特性に優れ収差も良好に補正できる導光光学系を実現したのである。尚、一方の面が光源側を向いていても良いし、偏向光学素子側を向いていても良い。 In the prior art, a light guiding optical system that uses two lenses to convert light emitted from a light source into a beam shape suitable for each of the main scanning direction and the sub scanning direction is used in each of the main scanning direction and the sub scanning direction. By using anamorphic surfaces with different powers, it is composed of only a single lens, and by this, a light guiding optical system is composed of a single lens, thereby realizing cost reduction. Furthermore, by providing a rotationally symmetric diffractive structure on a surface different from the anamorphic surface of the lens, a light guiding optical system that has excellent environmental resistance characteristics and can correct aberrations well is realized. One surface may face the light source side or the deflection optical element side.
　請求項２に記載の導光光学系は、請求項１に記載の発明において、前記レンズの前記他方の面は球面であることを特徴とする。 The light guiding optical system according to claim 2 is characterized in that, in the invention according to claim 1, the other surface of the lens is a spherical surface.
　ここで、レンズの一面を平面として回折構造を設けた場合、回折のパワーを環境変動時のピントずれの補正に使用する必要があるため、収差補正、特に軸外特性（コマ収差補正）を行う事が難しかった。一方、レンズの非球面に回折構造を設けた場合、レンズの誤差感度が増大し、組立難易度が高まる。特に、一方の面がアナモルフィックな面形状であるため、他方の面が非球面であると、向かい合う光学面同士を偏心なく製造することが非常に難しくなってしまう。これに対し、回折構造を付加する面を単純球面とすることで、面の偏心誤差感度を上げることなく効果的に収差補正を行う事が出来、また、一方の面がアナモルフィックであっても製造しやすいレンズを得られることが判明した。球面に回折構造を付加することで、レンズの両面でパワーを分散でき、回折のパワーを環境変化によるピント変動の補正に使用でき、正弦条件を良好に補正することが可能となる。 Here, when a diffractive structure is provided with one surface of the lens as a flat surface, it is necessary to use the power of diffraction for correcting the defocus when the environment changes, so aberration correction, particularly off-axis characteristics (coma aberration correction) is performed. It was difficult. On the other hand, when the diffractive structure is provided on the aspherical surface of the lens, the error sensitivity of the lens increases and the difficulty of assembly increases. In particular, since one surface has an anamorphic surface shape, if the other surface is an aspheric surface, it becomes very difficult to manufacture the optical surfaces facing each other without decentration. On the other hand, by making the surface to which the diffractive structure is added a simple spherical surface, it is possible to effectively correct aberrations without increasing the decentration error sensitivity of the surface, and one surface is anamorphic. It was also found that a lens that is easy to manufacture can be obtained. By adding a diffractive structure to the spherical surface, the power can be dispersed on both surfaces of the lens, and the diffractive power can be used to correct focus fluctuations due to environmental changes, and the sine condition can be corrected well.
　請求項３に記載の導光光学系は、請求項１又は２に記載の発明において、前記レンズの前記他方の面は、前記光源側に設けられていることを特徴とする。 The light guiding optical system according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the other surface of the lens is provided on the light source side.
　前記光源からの光が入射する面（曲率半径の絶対値が大きい面）に回折構造を付加することで、光学系全体として偏心誤差感度に強い系となる。 付 加 By adding a diffractive structure to the surface on which light from the light source is incident (a surface having a large absolute value of the radius of curvature), the entire optical system becomes a system that is highly resistant to eccentric error.
　請求項４に記載の導光光学系は、請求項１～３のいずれかに記載の発明において、前記レンズは、アクチュエータにより光軸方向に駆動可能となっていることを特徴とする。 The light guiding optical system according to a fourth aspect of the invention is characterized in that, in the invention according to any one of the first to third aspects, the lens can be driven in an optical axis direction by an actuator.
　前記レンズを光軸方向に駆動することによって、フォーカシング機能を持たせることで、環境変動時のピント変動をより効果的に補正可能となる。 By driving the lens in the direction of the optical axis to provide a focusing function, it is possible to more effectively correct focus fluctuations during environmental fluctuations.
　請求項５に記載の導光光学系は、請求項１～４のいずれかに記載の発明において、前記レンズは、前記光源側が凹のメニスカス形状であることを特徴とする。 The light guiding optical system according to claim 5 is characterized in that, in the invention according to any one of claims 1 to 4, the lens has a meniscus shape having a concave on the light source side.
　前記レンズの光源側の面に凹のメニスカス形状を採用することで、良好にコマ収差を補正することが可能となる。 By adopting a concave meniscus shape on the light source side surface of the lens, coma aberration can be corrected satisfactorily.
　請求項６に記載の導光光学系は、請求項１～５のいずれかに記載の発明において、前記回折構造は、ブレーズ形状を有することを特徴とする。 A light guiding optical system according to a sixth aspect is characterized in that, in the invention according to any one of the first to fifth aspects, the diffractive structure has a blaze shape.
　ブレーズ形状を有する回折構造により、良好に収差補正を行うことができる。ブレーズ形状とは、前記レンズの光軸を含む断面形状が鋸歯状の形状であることをいう。 Aberration correction can be performed satisfactorily by the diffractive structure having a blaze shape. The blaze shape means that the cross-sectional shape including the optical axis of the lens is a sawtooth shape.
　請求項７に記載の走査結像装置は、請求項１～６のいずれかに記載の導光光学系を有することを特徴とする。 A scanning image forming apparatus according to a seventh aspect includes the light guide optical system according to any one of the first to sixth aspects.
　本発明によれば、低コストでありながらも、耐環境特性に優れ収差も良好に補正できる導光光学系及びそれを用いた走査結像装置を提供することができる。 According to the present invention, it is possible to provide a light guide optical system that is low in cost and excellent in environmental resistance characteristics and that can correct aberrations well, and a scanning imaging apparatus using the same.
走査結像装置の主走査方向断面を示す図である。It is a figure which shows the main scanning direction cross section of a scanning imaging device. 導光光学系の断面図である。It is sectional drawing of a light guide optical system. （ａ）は、実施例１にかかる副走査方向断面（ｘｙ断面）図、（ｂ）は、実施例１にかかる主走査方向断面（ｚｘ断面）図である。(A) is a cross section in the sub-scanning direction (xy cross section) according to the first embodiment, and (b) is a cross section in the main scanning direction (zx cross section) according to the first embodiment.
　以下、図面を参照して本発明の実施の形態を詳細に説明する。図１は、走査光学系の光軸（主走査光軸ともいう）をｚ軸、主走査方向をｘ軸、副走査方向をｙ軸としたとき、走査光学系における光束の入射する面における主走査方向断面を示す図である。図２は、図１の導光光学系を拡大して示す図である。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a main surface on a surface on which a light beam is incident in the scanning optical system, where the optical axis (also referred to as main scanning optical axis) of the scanning optical system is the z axis, the main scanning direction is the x axis, and the sub scanning direction is the y axis. It is a figure which shows a scanning direction cross section. FIG. 2 is an enlarged view of the light guide optical system shown in FIG.
　図１において、本実施の形態にかかる走査結像装置ＳＦは、不図示の画像形成装置に組み込まれ、半導体レーザである光源ＬＤと、ポリゴンミラー等の偏向光学素子ＰＭと、光源ＬＤから出射された光を偏向光学素子ＰＭへ導光する導光光学系ＩＯＳと、偏向光学素子ＰＭにより偏向された光を走査し、像面に結像する走査光学系ＳＯＳとを有する。 In FIG. 1, a scanning imaging apparatus SF according to the present embodiment is incorporated in an image forming apparatus (not shown), and is emitted from a light source LD that is a semiconductor laser, a deflection optical element PM such as a polygon mirror, and a light source LD. A light guide optical system IOS that guides the reflected light to the deflection optical element PM, and a scanning optical system SOS that scans the light deflected by the deflection optical element PM and forms an image on the image plane.
　図２において、導光光学系ＩＯＳは樹脂レンズである単一のコリメートレンズＣＬからなり、コリメートレンズＣＬは、偏向光学素子ＰＭ側の面Ｓ２が、主走査方向と副走査方向とでパワーが異なるアナモルフィックな面形状を有し、光源ＬＤ側の面Ｓ１が、回転対称な回折構造を有している。光源ＬＤ側の面Ｓ１は球面であると好ましい。又、面Ｓ１の曲率半径の絶対値は面Ｓ２より大きい（面Ｓ１の近軸の屈折パワーの大きさが面Ｓ２より小さい）と好ましい。面Ｓ２の近傍に、開口絞りＡＰが設けられている。尚、主走査方向の自然収束点は、コリメートレンズＣＬの出射面から250mm以上離れた位置であると良い。温度変化に起因した樹脂素材の屈折率変化による（環境変動）補正は、主走査方向のピント変動を抑えるように設計している。 In FIG. 2, the light guide optical system IOS is composed of a single collimating lens CL that is a resin lens, and the collimating lens CL has a surface S2 on the deflection optical element PM side that has different powers in the main scanning direction and the sub-scanning direction. It has an anamorphic surface shape, and the surface S1 on the light source LD side has a rotationally symmetric diffraction structure. The surface S1 on the light source LD side is preferably a spherical surface. The absolute value of the radius of curvature of the surface S1 is preferably larger than the surface S2 (the paraxial refractive power of the surface S1 is smaller than the surface S2). An aperture stop AP is provided in the vicinity of the surface S2. Note that the natural convergence point in the main scanning direction is preferably located at a position 250 mm or more away from the exit surface of the collimating lens CL. The correction (environmental fluctuation) due to the refractive index change of the resin material due to the temperature change is designed to suppress the focus fluctuation in the main scanning direction.
　本実施の形態の変形例として、コリメートレンズＣＬを光軸方向に駆動するアクチュエータＡＣを設けて、フォーカシング機能を持たせ、これによりピントズレを補正するようにしても良い。 As a modification of the present embodiment, an actuator AC that drives the collimating lens CL in the optical axis direction may be provided to provide a focusing function, thereby correcting the focus shift.
　図１において、光源ＬＤから出射された光束Ｂは、導光光学系ＩＯＳ即ちコリメートレンズＣＬを通過し、開口絞りＡＰを通過し、偏向光学素子ＰＭの偏向反射面で反射され、走査光学系を構成する第１走査結像レンズＬ１，第２走査結像レンズＬ２を通過して、被走査面ＤＰ上に結像するようになっている。偏向光学素子ＰＭを回転させることにより、偏向反射面が傾くことで、光束Ｂは、少なくとも主走査方向のレンズ有効径Ｌの範囲で主走査方向に走査されるようになっており、これにより光走査を行い画像を形成することができる。 In FIG. 1, a light beam B emitted from a light source LD passes through a light guide optical system IOS, that is, a collimator lens CL, passes through an aperture stop AP, is reflected by a deflecting reflection surface of the deflecting optical element PM, and passes through the scanning optical system. The light passes through the first scanning imaging lens L1 and the second scanning imaging lens L2 and forms an image on the scanned surface DP. By rotating the deflection optical element PM, the deflection reflection surface is tilted, so that the light beam B is scanned in the main scanning direction at least in the range of the lens effective diameter L in the main scanning direction. Scanning can be performed to form an image.
　本実施形態によれば、１枚のコリメートレンズＣＬの面Ｓ２で、主走査方向、副走査方向それぞれに適したビーム形状に変換でき、又、面Ｓ１の回折構造により、優れた耐環境特性を確保し収差も良好に補正できる。 According to the present embodiment, the surface S2 of the single collimating lens CL can be converted into a beam shape suitable for each of the main scanning direction and the sub-scanning direction, and excellent environmental resistance characteristics can be obtained by the diffraction structure of the surface S1. It can be secured and aberrations can be corrected well.
　以下、本発明の実施の形態に好適な実施例であるコリメートレンズを説明する。尚、これ以降（表のレンズデータ含む）において、１０のべき乗数（例えば、２．５×１０-3）を、Ｅ（例えば、２．５×Ｅ－３）を用いて表す場合がある。また、レンズの回転対称球面又はアナモルフィック面については、表の数値に基づき、面形状が面頂点を原点とするローカルな直交座標系（ｘ，ｙ，ｚ）を用いた下記式で定義される自由曲面である。 Hereinafter, a collimating lens which is an example suitable for the embodiment of the present invention will be described. In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 −3 ) may be expressed using E (for example, 2.5 × E−3). For a rotationally symmetric spherical surface or anamorphic surface of a lens, the surface shape is defined by the following formula using a local orthogonal coordinate system (x, y, z) with the surface vertex as the origin based on the numerical values in the table. It is a free-form surface.
（数１）
ｚ＝ｃ・ｈ2／［１＋√｛１－（１＋Ｋ）・ｃ2・ｈ2｝］＋ｍΣｎΣ［Ｃ（ｍ，ｎ）・ｘm・ｙn］
但し、
ｚ：高さｈの位置でのｚ軸方向の変位量（面頂点基準）
ｈ：ｚ軸に対して垂直な方向の高さ（ｈ2＝ｘ2＋ｙ2）
ｃ：面頂点での曲率（＝１／曲率半径）
Ｋ：コーニック定数
Ｃ（ｍ，ｎ）：自由曲面係数（ｍ，ｎ＝０，１，２・・・） (Equation 1)
z = c · h 2 / [1 + √ {1− (1 + K) · c 2 · h 2 }] + mΣnΣ [C (m, n) · x m · y n ]
However,
z: Amount of displacement in the z-axis direction at the position of height h (based on the surface vertex)
h: Height in the direction perpendicular to the z-axis (h 2 = x 2 + y 2 )
c: curvature at the surface apex (= 1 / radius of curvature)
K: conic constant C (m, n): free-form surface coefficient (m, n = 0, 1, 2,...)
　また、レンズの回折構造により各波長の光束に対して与えられる光路差は、数２式の光路差関数に、表に示す係数を代入した数式で規定される。 Further, the optical path difference given to the light flux of each wavelength by the diffractive structure of the lens is defined by a mathematical formula obtained by substituting the coefficient shown in the table into the optical path difference function of Formula 2.
（数２）
Φ（ｈ）＝Σ（Ｃ１2ｈ2×λ×ｍ／λＢ）
ここで、λ：使用波長、ｍ：回折次数、λＢ：規格化波長、ｈ：光軸から光軸垂直方向の距離である。回折面の係数Ｃ１は-0.015≦Ｃ１≦-0.007であって、各表に示すとおりである。 (Equation 2)
Φ (h) = Σ (C1 2 h 2 × λ × m / λB)
Here, λ: wavelength used, m: diffraction order, λB: normalized wavelength, h: distance in the direction perpendicular to the optical axis from the optical axis. The coefficient C1 of the diffractive surface is −0.015 ≦ C1 ≦ −0.007, as shown in each table.
（実施例１）
　表１に実施例１のレンズデータを示す。図３（ａ）は、実施例１にかかる副走査方向断面（ｘｙ断面）図であり、図３（ｂ）は、実施例１にかかる主走査方向断面（ｚｘ断面）図である。凹のメニスカス形状を有する樹脂製のコリメートレンズの入射面Ｓ１は球面であって、光軸を中心とした輪帯状のブレーズ型回折構造が形成され、出射面Ｓ２はアナモルフィック面である。また、表１から明らかであるが、前記レンズの回折面Ｓ１における回折のパワーφ1、及び回折面Ｓ１における屈折のパワーφ2、は以下の式を満たす。
φ1＞0.01、φ2＜0、|φ1＋φ2|＞|φ2| Example 1
Table 1 shows lens data of Example 1. FIG. 3A is a cross section in the sub-scanning direction (xy cross section) according to the first embodiment, and FIG. 3B is a cross section in the main scanning direction (zx cross section) according to the first embodiment. The incident surface S1 of the resin collimating lens having a concave meniscus shape is a spherical surface, in which an annular blazed diffractive structure centering on the optical axis is formed, and the exit surface S2 is an anamorphic surface. As is clear from Table 1, the diffraction power φ1 at the diffraction surface S1 and the refraction power φ2 at the diffraction surface S1 of the lens satisfy the following equations.
φ1> 0.01, φ2 <0, | φ1 + φ2 |> | φ2 |
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
（実施例２）
　表２に実施例２のレンズデータを示す。実施例２の断面図は図３と同様である。凹のメニスカス形状を有する樹脂製のコリメートレンズの入射面Ｓ１は球面であって、光軸を中心とした輪帯状のブレーズ型回折構造が形成され、出射面Ｓ２はアナモルフィック面である。 (Example 2)
Table 2 shows lens data of Example 2. The cross-sectional view of Example 2 is the same as FIG. The incident surface S1 of the resin collimating lens having a concave meniscus shape is a spherical surface, in which an annular blazed diffractive structure centering on the optical axis is formed, and the exit surface S2 is an anamorphic surface.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　本発明は、明細書に記載の実施形態や実施例に限定されるものではなく、他の実施例・変形例を含むことは、本明細書に記載された実施形態や実施例や技術思想から本分野の当業者にとって明らかである。明細書の記載及び実施例は、あくまでも例証を目的としており、本発明の範囲は後述するクレームによって示されている。 The present invention is not limited to the embodiments and examples described in the specification, and includes other examples and modifications based on the embodiments, examples, and technical ideas described in the present specification. It will be apparent to those skilled in the art. The description and examples are for illustrative purposes only, and the scope of the invention is indicated by the following claims.
ＡＣ アクチュエータ
ＡＰ 開口絞り
Ｂ 光束
ＣＬ コリメートレンズ
ＤＰ 被走査面
ＩＯＳ 導光光学系
Ｌ１ 第１走査結像レンズ
Ｌ２ 第２走査結像レンズ
ＬＤ 光源
ＰＭ 偏向光学素子
ＳＦ 走査結像装置
ＳＯＳ 走査光学系 AC Actuator AP Aperture stop B Light beam CL Collimating lens DP Scanned surface IOS Light guide optical system L1 First scanning imaging lens L2 Second scanning imaging lens LD Light source PM Deflection optical element SF Scanning imaging device SOS Scanning optical system

Claims (7)

  1. 　光源から出射された光を偏向光学素子へ導光する導光光学系と、前記偏向光学素子により偏向された光を像面に結像する走査光学系とを有し、前記像面を光走査する走査結像装置に用いる導光光学系において、
    　前記導光光学系は単一の樹脂レンズからなり、前記レンズは、光軸方向を向いた一方の面が主走査方向と副走査方向とでパワーが異なるアナモルフィックな面形状であり、且つ他方の面が、回転対称な回折構造を有することを特徴とする導光光学系     A light guide optical system for guiding light emitted from the light source to the deflecting optical element; and a scanning optical system for forming an image on the image plane of the light deflected by the deflecting optical element, and optically scanning the image plane. In the light guide optical system used in the scanning imaging apparatus
    The light guide optical system is composed of a single resin lens, and the lens has an anamorphic surface shape in which one surface facing the optical axis direction has different powers in the main scanning direction and the sub scanning direction, and The light guide optical system characterized in that the other surface has a rotationally symmetric diffraction structure
  2. 　前記レンズの前記他方の面は球面であることを特徴とする請求項１に記載の導光光学系。 2. The light guide optical system according to claim 1, wherein the other surface of the lens is a spherical surface.
  3. 　前記レンズの前記他方の面は、前記光源側に設けられていることを特徴とする請求項１又は２に記載の導光光学系。 3. The light guide optical system according to claim 1, wherein the other surface of the lens is provided on the light source side.
  4. 　前記レンズは、アクチュエータにより光軸方向に駆動可能となっていることを特徴とする請求項１～３のいずれかに記載の導光光学系。 4. The light guiding optical system according to claim 1, wherein the lens is drivable in an optical axis direction by an actuator.
  5. 　前記レンズは、前記光源側が凹のメニスカス形状であることを特徴とする請求項１～４のいずれかに記載の導光光学系。 5. The light guide optical system according to claim 1, wherein the lens has a meniscus shape having a concave on the light source side.
  6. 　前記回折構造は、ブレーズ形状を有することを特徴とする請求項１～５のいずれかに記載の導光光学系。 6. The light guiding optical system according to claim 1, wherein the diffractive structure has a blazed shape.
  7. 　請求項１～６のいずれかに記載の導光光学系を有することを特徴とする走査結像装置。 A scanning imaging apparatus comprising the light guiding optical system according to any one of claims 1 to 6.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63249801A (en) * 1987-04-06 1988-10-17 Matsushita Electric Ind Co Ltd Anisotropic refracting power single lens
JP2005258392A (en) * 2004-02-12 2005-09-22 Ricoh Co Ltd Optical scanner and image forming apparatus
JP2006154748A (en) * 2004-10-28 2006-06-15 Canon Inc Optical scanning apparatus and method for adjusting the same
JP2011081382A (en) * 2009-10-07 2011-04-21 Samsung Electronics Co Ltd Optical scanner and electrophotographic image forming apparatus employing the same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63249801A (en) * 1987-04-06 1988-10-17 Matsushita Electric Ind Co Ltd Anisotropic refracting power single lens
JP2005258392A (en) * 2004-02-12 2005-09-22 Ricoh Co Ltd Optical scanner and image forming apparatus
JP2006154748A (en) * 2004-10-28 2006-06-15 Canon Inc Optical scanning apparatus and method for adjusting the same
JP2011081382A (en) * 2009-10-07 2011-04-21 Samsung Electronics Co Ltd Optical scanner and electrophotographic image forming apparatus employing the same

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