JP4075978B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

となる。
【００３４】
同様に、偏向反射面５ａに反射された光束に関して、
カバー部材１４による屈折光束と法線とのなす角度：γ
カバー部材１４の通る光束の光路長：ｕ
としたとき

となる。
【００３５】
以上説明した例では、光源部の光軸をシフトすることにより、防音・防塵等の役目を持つ透明なカバー部材の有無に対応させるようになっていたが、別の方法として、図７に示すように、光源部からの光束の射出方向を変えることによっても対応させることができる。図７において、光源部から光偏向器５へ向かう光束を、カバー部材１４がない場合は、カバー部材１４がある場合に対して角度ηだけ傾けている。
【００３６】
実際には、このとき光偏向器５の偏向反射面５ａに入射する光束と反射されて出射する光束とのなす角度θ´は、カバー部材１４がある場合に光偏向器５の偏向反射面５ａに入射する光束と反射されて出射する光束とのなす角度θに対して角度ηだけ狭く、
θ´＝θ−η
の関係になっており、光束をｘ軸と平行なｃ方向に反射させるためには、偏向反射面５ａの法線とｘ軸とのなす角度εが、
ε´＝ε−（η／２）
となっていればよい。
【００３７】
このように、光源部を平行移動しなくても、光源部からの光束の射出方向を変えることによって、防音・防塵等の役目を持つ透明なカバー部材１４の有無に対応させることができる。
また、上記のように、カバー部材１４の有無に応じて光源部からの光束の射出方向を変える場合でも、カバー部材１４によるいわゆる浮き上がりの影響は同じであるため、線像結像光学系４の配置位置、カップリングレンズ２からの射出光束の平行度、その他の各種設計条件は、光源部を平行移動させる場合と同様にすることができる。また、光源部の保持固定基準はこれを複数、すなわち、カバー部材１４がある場合に対応するものと、カバー部材１４がない場合に対応するものとを設ける。
【００３８】
なお、線像結像光学系と光源部とを別体とし、線像結像光学系の光軸方向に関する配置位置をずらすことによって、上記カバー部材の有無に対応させるようにしてもよい。その場合は、カップリングレンズからの射出光束は略平行光束である必要はなく、発散光束でも集束光束であっても差し支えない。その場合、光源部の光軸方向の位置を、カバー部材を配置したことによるいわゆる浮き上がりの影響を補正することができる位置に配置する必要がある。
【００３９】
【発明の効果】
請求項１記載の発明によれば、光源とカップリングレンズとから構成される光源部と、光学ハウジングの少なくとも一方には、光源部を保持し固定するための保持固定基準が設けられており、この保持固定基準は複数であるため、光学系の構成および光学ハウジングの構成を共通化し、光偏向器の周りを覆うカバーの窓孔に透明カバー部材を配置した高速用の場合と、透明カバーを有しない低速用の場合とで、光源部の保持固定基準を使い分ければよく、光走査装置の開発コストの低減、開発時間の短縮化を図ることができる。特に光学ハウジングの共通化により、その金型は一つで足りることになり、この点でのコストの低減効果は大きい。
【００４０】
請求項２記載の発明によれば、光源部と線像結像光学系は同一部材上に配置し、これらを一体として位置を変えることにより、透明カバーを有している場合と有していない場合とでの、副走査方向の結像位置ずれを補正することができる。また、光源部と線像結像光学系が一体であることによって、組み立て、調整作業を簡易化することができる。
【００４１】
請求項３記載の発明によれば、カップリングレンズと線像結像光学系を一体化することによって、部品点数の低減、部品の小型化、省資源化を図ることができる。
請求項４記載の発明によれば、光源部を複数の発光源から構成することにより、より一層の高速化を図ることができる。
請求項５記載の発明によれば、光源部から発せられる光束を略平行光束とすることにより、透明カバー部材の有無による主走査方向の結像位置ずれをなくすことができる。
【図面の簡単な説明】
【図１】本発明を適用可能な光走査装置の光学配置例を示す斜視図である。
【図２】本発明に適用可能な光源部の例を示す斜視図である。
【図３】本発明に適用可能な光源部の別の例を示す斜視図である。
【図４】透明カバー部材がある場合とない場合の副走査対応方向断面における結像位置のずれを示す光路図である。
【図５】透明カバー部材がある場合とない場合とで光源部からの光束のずらし量を求める方法を説明するための光路図である。
【図６】上記ずらし量を求める方法をより詳細に説明するための光路図である。
【図７】透明カバー部材がある場合とない場合とで光源部からの光束の入射角度を変えるようにした例を示す光路図である。
【図８】光偏向器とそのカバーと透明カバー部材を示す平面断面図である。
【符号の説明】
１ 光源
２ カップリングレンズ
４ 線像結像光学系
５ 光偏向器
９ 被走査媒体
１３ カバー
１４ 透明カバー部材
１５ 光源部
１７ 走査結像系[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical scanning device used in a writing system of a recording apparatus such as a digital copying machine, a laser printer, or a laser facsimile, and in particular, a cover member is attached to an incident / exit window of a cover that covers an optical deflector. The present invention relates to an optical scanning device that can easily cope with cases and cases where it is not attached.
[0002]
[Prior art]
In recent years, there has been a demand for an improvement in recording speed in an optical scanning device used in a writing system of a recording apparatus such as a digital copying machine, a laser printer, or a laser facsimile. As a means for improving the recording speed, for example, there is a method of increasing the deflection speed by an optical deflector composed of a rotating polygon mirror (polygon mirror), that is, a method of increasing the rotational speed of the optical deflector. However, in this method, noise generated by the optical deflector, particularly in the case of a rotating polygon mirror, increases the wind noise at the edge portion, so that measures are taken to reduce noise.
[0003]
As a measure for reducing noise, the optical deflector is generally covered with a cover. An incident / exit window for guiding the light beam to the optical deflector and emitting the deflected light beam to the outside is covered with a transparent material such as glass. By doing so, it is possible to prevent noise generated by the optical deflector from leaking to the outside. This also serves as a dustproof measure for the optical deflector.
[0004]
As described above, while the recording speed of the optical scanning device can be improved, development aimed at realizing a low-cost optical scanning device or an image forming apparatus using the same is performed even if the recording speed is low. It has been broken. Under these circumstances, if an optical system aimed at improving recording speed and an optical system aimed at low speed and low cost are separately developed, each requires development time and costs. End up. Therefore, an optical system having the same configuration is used, and a soundproof / dustproof transparent cover member is attached to the high-speed optical scanning device, and a soundproof / dustproof transparent cover member is omitted from the low-speed optical scanning device. It is considered.
[0005]
However, the transparent cover member having functions such as soundproofing and dustproofing has a refracting action, and when this cover member is used, the optical path of the light beam is changed compared to the case where this cover member is not used. The layout of each optical element differs depending on whether the cover member is used or not. Therefore, conventionally, separate optical housings corresponding to the case where the cover member is used and the case where the cover member is not used have been made. Making the optical housing separately in this way means that a mold for molding the optical housing is also required separately, which increases the development cost.
[0006]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described problems of the prior art, and makes it possible to share an optical housing with and without the use of a soundproof / dustproof transparent cover member. An object of the present invention is to provide an optical scanning device capable of reducing the development cost and shortening the development period.
[0007]
When the transparent cover member is used, as described above, there is a refraction action called lifting, so that the image position of the line image formed by the line image imaging system is shifted depending on the presence or absence of the cover member. If this image forming position is shifted, the image forming position in the sub-scanning direction on the surface of the scanned medium is also shifted. Therefore, it is necessary to change the position of the line image forming optical system according to the presence or absence of the cover member.
Therefore, another object of the present invention is to provide an optical scanning in which the light source unit and the line image imaging optical system are arranged on the same member so that the light source unit and the line image imaging optical system can be positioned simultaneously. To provide an apparatus.
[0008]
As described above, enabling the light source unit and the line image imaging optical system to be positioned substantially integrally changes the distance between the light source unit and the optical deflector. If the light beam from the light source part is a divergent light beam or a convergent light beam, the distance between the light source part and the optical deflector changes as described above, so that the imaging position in the main scanning direction on the surface of the scanned medium is also changed. Such a problem occurs that the beam diameter increases due to the imaging position shift.
Therefore, still another object of the present invention is to provide an optical scanning device capable of preventing an imaging position shift even when the distance between the light source unit and the optical deflector changes.
[0009]
Still another object of the present invention is to provide an optical scanning device that can reduce the number of components and the size of a movable part by using a coupling lens and a line image forming optical system as one lens. It is in.
It is another object of the present invention to provide an optical scanning device that uses a plurality of light sources to increase the number of scanning lines and cope with high speed.
[0010]
[Means for Solving the Problems]
  The invention according to claim 1 is a light source, a coupling lens for coupling a divergent light beam emitted from the light source, an optical deflector for deflecting the light beam from the coupling lens at an equal angular velocity, and the coupling lens. A line image imaging optical system that is arranged between the optical deflectors and forms a light beam in a linear shape in the main scanning direction in the vicinity of the deflecting reflection surface of the optical deflector, and a light beam deflected by the optical deflector to be scanned A scanning imaging system that forms an image as a light spot, and an optical housing in which these light source, coupling lens, optical deflector, line image imaging optical system, and scanning imaging system are arranged and housed, and Light source and coupling lensHaveAt least one of the light source unit and the optical housing has a holding and fixing reference for holding and fixing the light source unit.MultipleProvided,The optical deflector is covered with a cover and has a window for light flux to enter and exit the optical deflector. A transparent cover member can be disposed in the window. The holding and fixing reference is determined so that the deflected light beam passes through substantially the same position of the scanning imaging system when the cover member is attached and when it is not attached.It is characterized by that.
[0012]
  Claim2The described invention is claimed.1In the mounted invention, the light source unit and the line image imaging optical system are arranged on the same member.
  Claim3The described invention is claimed.1In the invention described above, the coupling lens and the line image imaging optical system are integrally formed.
[0013]
  Claim4The described invention is claimed.1In the invention described above, the light source section is composed of a plurality of light emitting sources.
  Claim5The described invention is claimed.2 or 3In the described invention, the light beam emitted from the light source unit is a substantially parallel light beam.
  According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising the optical scanning device according to any one of the first to fifth aspects.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an optical scanning device according to the present invention will be described with reference to the drawings.
First, a configuration example of the entire optical scanning device will be schematically described. In FIG. 1, reference numeral 1 denotes a light source made of, for example, a semiconductor laser, and reference numeral 2 denotes a coupling lens. The divergent light beam emitted from the light source 1 is coupled and converged by the coupling lens 2 and shaped into a predetermined cross-sectional shape by the aperture 3 as a light beam shaping means. A cylindrical lens 4 as a line image imaging optical system is disposed on the path of the light beam that has passed through the aperture 3, and an optical deflector 5 including a rotating polygon mirror is disposed further ahead.
[0015]
The cylindrical lens 4 focuses the light beam transmitted through the aperture 3 only in the sub-scanning corresponding direction, and forms a long line image in the main scanning corresponding direction in the vicinity of the deflection reflection surface of the optical deflector 5. The optical deflector 5 deflects the light beam from the light source 1 side in a predetermined angular range at a uniform angular velocity. The deflected light beam passes through the scanning imaging optical system 17 and scans the scanned medium 9. The substance of the scanned medium 9 is a photoconductive photoconductor. The scanning imaging optical system 17 includes an imaging lens 6 and a long lens 7 that is long in the main scanning direction, and the light beam deflected at a constant angular velocity by the optical deflector 5 is incident on the scanned medium 9. An image is formed as a spot and scanned on the scanned medium 9 at a constant speed. A long mirror 8 that bends the optical path is disposed between the scanning imaging optical system 17 and the scanned medium 9.
[0016]
In FIG. 1, reference numeral 100 denotes a synchronization detection optical system. The synchronization detection optical system 100 includes a mirror 10, a lens 11, and a light receiving element 12. The mirror 10 is arranged between the imaging lens 6 and the long lens 7 so as to reflect the light beam near the deflection start end in the light deflection range by the light deflector 5 toward the lens 11 and the light receiving element 12. ing. The light receiving element 12 outputs a signal by detecting the light beam near the deflection start end. As is well known, this signal is used to determine the write start timing as a synchronization signal.
The optical system including the light source 1, the coupling lens 2, the optical deflector 5, the line image imaging optical system 4, the scanning imaging system 17, the long mirror 8, and the synchronization detection optical system 100 is predetermined in an optical housing (not shown). Positioned and stored in position.
[0017]
The configuration of the optical scanning device shown in FIG. 1 is basically the same for high-speed scanning and low-speed scanning, and can be commonly applied to both high-speed scanning and low-speed scanning. However, when used for high-speed scanning, wind noise caused by high-speed rotation of the optical deflector 5 becomes a problem as noise as described above. Therefore, in order to prevent this noise from leaking outside, the periphery of the optical deflector 5 is covered with a sound-proof cylindrical cover 13 as shown in FIG. The cover 13 is formed with a window for allowing the light deflector 5 to enter and exit the light beam. When used for high-speed scanning, a transparent cover member 14 for soundproofing and dustproofing is disposed on the window, and the window It is blocked. In this way, noise generated by the high-speed rotation of the optical deflector 5 is prevented from leaking to the outside.
[0018]
Regardless of the presence or absence of the cover member 14, optical elements such as the optical deflector 5, the imaging lens 6, and the long lens 7 are almost shared. However, since the transparent cover member 14 is disposed in the optical path of the optical system, the optical path changes due to a phenomenon of so-called floating when the light beam passes through the cover member 14. Therefore, the position of the light beam passing through the imaging lens 6 and the long lens 7 changes only by arranging the cover member 14 without changing the light source unit and other arrangement positions, as if the optical system after the optical deflector 5 is The image forming position shifts as if it is shifted in the direction perpendicular to the lens optical axis in the deflection scanning plane, so-called beam thickening occurs on the scanned medium 9, and image quality is deteriorated. This problem is also pointed out in Japanese Patent No. 2550153 owned by the present applicant.
[0019]
FIG. 5 specifically illustrates the above problem. In FIG. 5, symbol a indicates an optical path of a light beam from the light source unit toward the optical deflector 5, a solid line indicates an optical path when the cover member 14 enters the optical path, and a broken line indicates a case where there is no cover member 14. The optical path is shown. When the cover member 14 enters the optical path, the light beam is emitted from the cover member 14 when entering from the light source unit toward the optical deflector 5 and when being deflected and emitted by the deflecting reflection surface 5a of the optical deflector 5. The light is refracted and emitted as indicated by reference c. On the other hand, when the cover member 14 is not provided, there is no refraction at the time of entering / exiting the optical deflector 5 and, as indicated by the symbol d, the light exits along an optical path different from the case where the cover member 14 is in the optical path. I will do it. This is a state as if the optical system after the optical deflector 5 has been shifted in the direction perpendicular to the lens optical axis in the deflection scanning plane, and the image formation position by rotation of the field curvature is as follows. The misalignment causes so-called beam thickening and the like, causing deterioration in image quality.
[0020]
Therefore, when the case where the cover member 14 is present is considered as a reference, and the cover member 14 is not present, in FIG. 5, the optical path of the light beam reflected and emitted as a result by the deflection reflection surface 5 a of the optical deflector 5 is obtained. The optical path from the light source unit is shifted in the direction perpendicular to the optical axis of the light beam from the light source unit in the deflection plane so as to overlap the optical path c of the light beam emitted when the cover member 14 is present. In FIG. 5, this shift amount is represented by Δ, and the incident optical path at that time is represented by b. As described above, with or without the cover member 14, the optical path of the light beam traveling from the light source unit toward the optical deflector 5 is shifted in the direction perpendicular to the optical axis of the light beam from the light source unit within the deflection surface. Since the optical paths emitted from the optical deflector 5 can be made to coincide with each other and the deviation of the imaging position can be eliminated, it is possible to obtain a high quality image by eliminating the deviation of the imaging position regardless of whether or not the cover member 14 is present. Obtainable.
[0021]
As described above, in order to shift the optical path of the light beam from the light source portion toward the optical deflector 5 with and without the cover member 14, the optical housing includes the light source 1 and the coupling lens 2. For the holding and fixing reference for holding and fixing the light source unit, a plurality of standards corresponding to the case where the cover member 14 is present and a plurality of standards corresponding to the case where the cover member 14 is not provided are provided, and these standards may be properly used. . Specific examples thereof will be described below.
[0022]
In FIG. 2, the code | symbol 15 shows a light source part. The light source unit 15 is configured as a holding member that holds the light source 1 and the coupling lens 2. The light source unit 15 includes a plate-like vertical member 15a that holds the light source 1 and the coupling lens 2, and a plate-like horizontal member 15b to which the bottom surface of the member is fixed. Four holes A1, A2, B1, and B2 are formed in the vertical direction at positions corresponding to the corners. On the other hand, the optical housing for fixing the light source unit 15 is provided with pins a1 and a2 corresponding to the holes A1 and A2, and pins b1 and b2 corresponding to the holes B1 and B2, respectively.
[0023]
The pair of pins a1 and a2 and the other pair b1 and b2 form a holding and fixing reference for holding and fixing the light source unit 15, and the pair of pins a1 and a2 are held and fixed when the cover member 14 is provided. Then, the pair of pins b1 and b2 is a holding and fixing reference when the cover member 14 is not provided. The pair of pins a1 and a2 and the other pair of b1 and b2 are arranged so that one of them holds and fixes the light source unit 15 so that the other does not get in the way, or the other pin escapes. Is configured so as not to interfere with each other. As described above, since there are a plurality of holding and fixing references of the light source unit 15 corresponding to the case where the cover member 14 is present and the case where the cover member 14 is not present, the position of the light source unit 15 is determined depending on whether the cover member 14 is present or not. By changing the value at, the deviation of the imaging position can be eliminated.
[0024]
In the configuration shown in FIG. 2, the pair of pins a1 and a2 and the other pair of pins b1 and b2 have been described as the holding and fixing reference of the light source unit 15, respectively, but the pair of holes A1 and A2 on the light source unit 15 side and the pair of pins The holes B1 and B2 may be used as the holding and fixing reference. In addition, when the pair of pins a1 and a2 and the other pair of pins b1 and b2 are used as a holding and fixing reference, only one pair of holes on the light source unit side is used and the pair of pins a1 and a2 or another pair of pins is used. The position of the light source unit 15 may be changed by selectively fitting to b1 and b2. Conversely, when the pair of holes A1 and A2 and the pair of holes B1 and B2 are used as the holding and fixing reference, only one pair of pins on the optical housing side is provided, and the pair of holes A1 and A2 or the pair of holes B1 and B2 May be selectively fitted to change the position of the light source unit 15. Further, a pin may be provided on the light source unit 15 side, and a hole that fits into the pin may be provided on the optical housing side. In short, at least one of the light source unit 15 and the optical housing is provided with a holding and fixing reference for holding and fixing the light source unit 15, and the holding and fixing reference may be plural.
[0025]
Next, the shift of the imaging position in the cross section in the sub-scanning direction with and without the cover member 14 will be described with reference to FIG. In FIG. 4, the state indicated by the solid line l is a state where there is no cover member 14. A light beam from the light source is imaged in the vicinity of the deflecting and reflecting surface 5a by the line image imaging optical system 4 in a long line shape in the main scanning direction, and a scanning imaging system that is a composite system of the imaging lens 6 and the long lens 7 is used. 17 forms an imaging spot on the scanned medium 9. In FIG. 4, a state indicated by a dotted line m is a state in which the cover member 14 is used. In this state, the light beam that has passed through the line image forming optical system 4 is refracted (lifted) by the cover member 14, and the line image in the vicinity of the deflecting reflection surface 5a is shifted toward the scanned medium 9 by Δx. A magnification is applied by the imaging lateral magnification β in the sub-scanning direction of the scanning imaging system 17, and the imaging position of the scanned medium 9 is shifted by Δx ′. The relationship is obtained by the following formula.
Δx ′ = Δx · β²
[0026]
As described above, in the cross section in the sub-scanning direction, when the cover member 14 is present, the imaging position shift is Δx ′ in the optical axis direction at the position of the scanned medium 9 as compared with the case where the cover member 14 is not present. I will wake you up. In order to eliminate this imaging position shift, it is necessary to move the line image imaging optical system 4 in the optical axis direction by Δx. At this time, if the light source unit is configured to be able to hold the line image imaging optical system 4, the light source unit and the line image imaging optical system may or may not enter the cover member 14. 4 can be dealt with easily by shifting them together in the direction of the optical axis. In that case, the line image forming system 4 is positioned at the reference position so that the position of the line image forming system 4 is optimal in relation to the light source unit.
[0027]
FIG. 3 shows a specific configuration example for positioning the line image imaging system 4 so that the position of the line image imaging system 4 is optimal in relation to the light source unit 15. The plate-like vertical piece 16a is integrated with the plate-like vertical piece 16a. There is a holding member 16 composed of a plate-like horizontal piece 16 b, and the light source unit 15 is attached to the vertical piece 16 a of the holding member 16. A pair of square columnar reference support pieces 16c and 16c are integrally provided on the horizontal piece 16b, and the left and right ends of the line image imaging system 4 are provided on one side of the reference support pieces 16c and 16c. The one surface faces each other, and the line image forming system 4 is pressed and fixed to the reference support pieces 16c and 16c by a holding and fixing plate spring or the like (not shown). As described above, the line image imaging system 4 is disposed on the same holding member 16 as the light source unit 15, so that the position of the line image imaging system 4 in the optical axis direction is optimal in relation to the light source unit 15. Is positioned. The line image forming system 4 may be fixed to the reference support pieces 16c and 16c by adhesion.
[0028]
The horizontal piece 16b of the holding member 16 is formed with a hole for fixing the light source unit 15 and the line image forming system 4 integrated therewith at a predetermined reference position. This hole is adapted to be fitted to a pin on the optical housing side, and by selecting a pin to fit the hole or by selecting a hole to be fitted to a specific pin, the case with or without the cover member 14 is provided. Accordingly, the position of the holding member 16 in the optical axis direction can be changed.
[0029]
In the case of the example shown in FIG. 3, in order to set the distance between the holding member 16 and the optical deflector 5 so as to optimize the position of the line image imaging optical system 4 according to the presence or absence of the cover member 14, the light source 1 and The distance between the coupling lens 2 and the optical deflector 5 also changes depending on the presence or absence of the cover member 14, and the deviation of the imaging position in the cross section in the sub-scanning corresponding direction is corrected. However, since the overall magnification in the main scanning direction is different from that in the sub scanning direction, the imaging position in the main scanning direction is not corrected even if the imaging position in the sub scanning direction is corrected. Therefore, it is desirable that the light beam emitted from the coupling lens 2 is a substantially parallel light beam that is not affected by the position of the line image forming optical system 4. By making the light beams substantially parallel, the light beams incident on the scanning imaging system 17 in the main scanning direction remain substantially parallel light beams and do not affect the imaging state of the scanning imaging system 17.
When the light beam from the coupling lens 2 is a divergent light beam or a convergent light beam, the distance relationship between the natural light condensing point and the scanned medium 9 is changed, so that the image forming state by the scanning image forming system 17 is affected. The image formation state is deteriorated, and the image quality is deteriorated due to an increase in beam diameter or the like.
[0030]
As a method of speeding up optical writing or image formation, a method of improving the mechanical output speed by combining a light source unit with a plurality of light-emitting light sources to form a so-called multi-beam and speeding up the optical deflector can be considered. .
In order to cope with both speed-up of optical writing or image formation by speeding up the multi-beam and the optical deflector and speed-down using the same optical system, the following is performed. That is, when configuring a low-speed output machine, a single light source is used, the optical deflector is also rotated at a speed that does not bother the wind noise, and the cover member 14 is omitted. When configuring a high-speed output machine, the transparent cover member 14 is inserted to cope with wind noise caused by a high-speed rotation of the optical deflector and a high-speed rotation of the optical deflector. Further, when a semiconductor laser array having a plurality of light emitting points is housed in one package and used as a light source, there is an advantage that the holding parts of the semiconductor laser can be shared with the case of one light emitting point.
[0031]
On the other hand, from the viewpoint of compactness, there is a method in which the coupling lens 2 and the line image imaging optical system 4 are integrated to reduce the size of the holding member 16 shown in FIG. Also in this case, it is desirable that the light beam emitted from the integrated coupling lens 2 is a substantially parallel light beam as described above.
[0032]
Next, a specific method for deriving the shift amounts of the light source unit 15 and the holding member 16 will be described with reference to FIG. In FIG. 5, when the cover member 14 is used, the optical axis of the light beam a from the light source unit 15 is shifted by Δ1 by the transparent cover member 14. The luminous flux is reflected by the deflecting reflection surface 5a, and the optical axis is shifted by Δ2 again by the transparent cover member 14. The sum of these deviations △ 1 and △ 2, that is,
△ = △ 1 + △ 2
Is the amount of shift of the light source unit in the direction perpendicular to the optical axis. In the figure, the direction parallel to the optical axis of the scanning imaging system is taken as the x-axis, and the direction orthogonal thereto is taken as the y-axis. In addition, let the emitted light beam c from the cover member 14 be a direction parallel to the x-axis.
[0033]
FIG. 6 shows FIG. 5 in more detail. In FIG.
The angle of the cover member 14 with respect to the y axis: φ
Angle formed between the light beam incident on the deflecting reflection surface 5a and the reflected light beam: θ
Angle formed by the normal of the cover member 14 and the incident light beam a: θ−φ
Angle between refraction light beam and normal by cover member 14: α
Refractive index of cover member 14: n
Optical path length of light beam passing through cover member 14: S
Cover member 14 thickness: t
When

It becomes.
[0034]
Similarly, with respect to the light beam reflected by the deflecting reflection surface 5a,
Angle formed between the refracted light beam by the cover member 14 and the normal line: γ
Optical path length of the light beam passing through the cover member 14: u
When

It becomes.
[0035]
In the example described above, the optical axis of the light source unit is shifted to correspond to the presence or absence of a transparent cover member having a role of soundproofing / dustproofing, but another method is shown in FIG. As described above, this can be dealt with by changing the direction of emission of the light beam from the light source section. In FIG. 7, when the cover member 14 is not provided, the light beam traveling from the light source unit toward the optical deflector 5 is inclined by an angle η with respect to the case where the cover member 14 is provided.
[0036]
Actually, the angle θ ′ formed between the light beam incident on the deflecting / reflecting surface 5a of the optical deflector 5 and the light beam reflected and emitted at this time is the deflecting / reflecting surface 5a of the optical deflector 5 when the cover member 14 is present. The angle η is narrower than the angle θ formed by the light beam incident on the light beam and the light beam reflected and emitted,
θ ′ = θ−η
In order to reflect the light beam in the c direction parallel to the x axis, the angle ε between the normal line of the deflecting / reflecting surface 5a and the x axis is
ε ′ = ε− (η / 2)
It only has to be.
[0037]
Thus, even if the light source unit does not move in parallel, it is possible to cope with the presence or absence of the transparent cover member 14 having a role such as soundproofing and dustproofing by changing the emission direction of the light beam from the light source unit.
Further, as described above, even when the emission direction of the light beam from the light source unit is changed in accordance with the presence or absence of the cover member 14, the effect of so-called lifting by the cover member 14 is the same. The arrangement position, the parallelism of the light beam emitted from the coupling lens 2, and other various design conditions can be the same as in the case of moving the light source unit in parallel. Further, a plurality of holding and fixing references for the light source unit are provided, that is, one corresponding to the case where there is the cover member 14 and one corresponding to the case where there is no cover member 14.
[0038]
The line image imaging optical system and the light source unit may be separated from each other, and the arrangement position of the line image imaging optical system in the optical axis direction may be shifted to correspond to the presence or absence of the cover member. In that case, the light beam emitted from the coupling lens does not need to be a substantially parallel light beam, and may be a divergent light beam or a convergent light beam. In that case, it is necessary to arrange the position of the light source portion in the optical axis direction at a position where the influence of the so-called floating due to the arrangement of the cover member can be corrected.
[0039]
【The invention's effect】
  Claim1According to the invention described above, the holding and fixing reference for holding and fixing the light source unit is provided in at least one of the light source unit including the light source and the coupling lens and the optical housing. Since there are a plurality of standards, the configuration of the optical system and the configuration of the optical housing are made common, and the case of high speed with a transparent cover member arranged in the window hole of the cover covering the periphery of the optical deflector, and the low speed without a transparent cover It is only necessary to use different holding and fixing standards for the light source part, and it is possible to reduce the development cost and the development time of the optical scanning device. In particular, since the optical housing is made common, only one mold is required, and the cost reduction effect in this respect is great.
[0040]
  Claim2According to the described invention, the light source unit and the line image imaging optical system are arranged on the same member, and these are integrated to change the position, so that the case with or without the transparent cover is provided. It is possible to correct the imaging position shift in the sub-scanning direction. Further, since the light source unit and the line image forming optical system are integrated, assembly and adjustment operations can be simplified.
[0041]
  Claim3According to the described invention, by integrating the coupling lens and the line image forming optical system, it is possible to reduce the number of parts, downsize parts, and save resources.
  Claim4According to the described invention, it is possible to further increase the speed by configuring the light source unit from a plurality of light emitting sources.
  Claim5According to the described invention, by making the light beam emitted from the light source unit a substantially parallel light beam, it is possible to eliminate the image forming position deviation in the main scanning direction due to the presence or absence of the transparent cover member.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an optical arrangement example of an optical scanning apparatus to which the present invention can be applied.
FIG. 2 is a perspective view showing an example of a light source unit applicable to the present invention.
FIG. 3 is a perspective view showing another example of a light source unit applicable to the present invention.
FIG. 4 is an optical path diagram showing a shift in image forming position in a cross section corresponding to the sub-scanning direction with and without a transparent cover member.
FIG. 5 is an optical path diagram for explaining a method of obtaining a shift amount of a light beam from a light source unit with and without a transparent cover member.
FIG. 6 is an optical path diagram for explaining the method for obtaining the shift amount in more detail.
FIG. 7 is an optical path diagram showing an example in which the incident angle of the light beam from the light source section is changed with and without the transparent cover member.
FIG. 8 is a plan sectional view showing an optical deflector, its cover, and a transparent cover member.
[Explanation of symbols]
1 Light source
2 Coupling lens
4 Line image imaging optical system
5 Optical deflector
9 Scanned media
13 Cover
14 Transparent cover member
15 Light source
17 Scanning imaging system

Claims (6)

A light source, a coupling lens for coupling a divergent light beam emitted from the light source, an optical deflector for deflecting the light beam from the coupling lens at an equiangular velocity, and disposed between the coupling lens and the optical deflector. A linear image forming optical system that forms a light beam in a linear shape in the main scanning direction in the vicinity of the deflecting reflection surface of the optical deflector, and an image of the light beam deflected by the optical deflector as a light spot on the scanned medium A scanning imaging system, and an optical housing in which the light source, coupling lens, optical deflector, line image imaging optical system, and scanning imaging system are disposed and housed,
A light source section that have a the light source and the coupling lens, at least one of the optical housing, holding fixed reference for fixing holding the light source unit is provided with a plurality,
The optical deflector is covered with a cover and has a window for the light beam to enter and exit the optical deflector, and a transparent cover member can be disposed on the window.
The light fixing and fixing reference of the light source unit is determined so that the deflected light beam passes through substantially the same position of the scanning imaging system when the cover member is attached and when the cover member is not attached. Scanning device. 2. The optical scanning device according to claim 1, wherein the light source unit and the line image imaging optical system are disposed on the same member . The optical scanning apparatus according to claim 1 Symbol mounting, the coupling lens and the linear image forming optical system is an optical scanning apparatus characterized by being formed integrally. The optical scanning apparatus according to claim 1 Symbol placement, the light source unit is an optical scanning apparatus characterized by comprising formed by a plurality of light emitting sources. 4. The optical scanning device according to claim 2, wherein the light beam emitted from the light source unit is a substantially parallel light beam . An image forming apparatus comprising the optical scanning device according to claim 1 .

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