JPS6055327A - Correcting device of uneven illuminance in variable magnification copying machine - Google Patents

Abstract

PURPOSE:To correct illuminance irregularity on the photosensitive body of a slit exposure type variable magnification copying machine which varies in magnification by moving a lens in the optical-axis direction of an optical path through simple constitution without spoiling illumination efficiency greatly. CONSTITUTION:A correcting plate 11 which does not cut off luminous flux at life-size magnification and increases in the shielding amount of both end parts of the optical path between the surface of an original at an exposure optical system and the lens 8 as the magnification decreases is fixed to a machine frame at both breadthwise sides of the optical path. Consequently, the angle of incidence of luminous flux cut off by the correcting plate 11 to the lens 8 decreases according to the distance from the outermost point A of a slit to the center to reduce the width of a shade appearing on the lens, and the luminous flux is cut off only by a part of the correcting plate 11 at a point B, so the width Wb of the shade is further reduced. For the purpose, the position, shape, and size of the correcting plate 11 position are so predetermined that the ratio of the area of the shade on the lens to the area of an entrance pupil may be equivalent to the ratio of the uneven illuminance in the photosensitive body in the longitudinal direction of the slit at reduction magnification, correcting the uneven illuminance on the photosensitive body in the longitudinal direction of the slit.

Description

【発明の詳細な説明】 技術分野 この発明は、レンズを光路の光軸方向に移動させて変倍
を行なうスリット露光方式の変倍複写機におけるスリッ
ト長手方向の照度ムラ補正装置に関する。TECHNICAL FIELD The present invention relates to an apparatus for correcting illuminance unevenness in the longitudinal direction of a slit in a variable magnification copying machine of a slit exposure type that changes magnification by moving a lens in the optical axis direction of an optical path.

従来技術 電子写真複写機の露光々学系としては、第１図に示す如
く、複写機本体１の頂板に設けられたコンタクトガラス
２上に載置された原稿３を光源４によりスリット照射し
、その反射光束を上記光源４と一体に一定の速度Ｖで移
動する第１ミラー５、その捧の速度で移動する第２ミラ
ー６、第６ミラー７で反射させて、レンズ８、第４ミラ
ー９を経て周速Ｖで回転する感光体ドラム１０上に結像
させて露光するスリット露光方式の光学系が多く用いら
れている。As shown in FIG. 1, the exposure system of a prior art electrophotographic copying machine is such that a document 3 placed on a contact glass 2 provided on the top plate of a copying machine body 1 is irradiated with a slit by a light source 4. The reflected light flux is reflected by a first mirror 5 that moves at a constant speed V together with the light source 4, a second mirror 6 and a sixth mirror 7 that move at the same speed, and is reflected by a lens 8 and a fourth mirror 9. A slit exposure type optical system is often used in which an image is formed on a photoreceptor drum 10 rotating at a circumferential speed V and exposed to light.

この構成の光学系で、変倍複写を行なうには、等倍複写
時に実線で示す位置にあったレンズ８を、縮小時は例え
ば鎖線８′で示す如く像側に、拡大時には鎖線８“で示
す如く物体側に変位させ第２、第３ミラー６．７は一体
的にレンズ８から離れる方向に例えば６′、７′の位置
に変位させた後、感光体ドラム１０の周速はＶのまくで
、光源４と第１ミラー５をＶ／ｍの速度で第２、第３ミ
ラー６．７をＶ／２　ｍの速度で同期させて同方向に移
動させて露光走査を行なう。なおｍは倍率である。In order to perform variable magnification copying in an optical system with this configuration, the lens 8, which was at the position shown by the solid line during full-scale copying, is moved to the image side as shown by the chain line 8' during reduction, and as shown by the chain line 8'' during enlargement. As shown, the second and third mirrors 6.7 are integrally moved away from the lens 8 to positions 6' and 7', for example, and then the circumferential speed of the photosensitive drum 10 is increased to V. Exposure scanning is performed by synchronizing the light source 4 and the first mirror 5 at a speed of V/m and the second and third mirrors 6.7 at a speed of V/2 m in the same direction. is the magnification.

従来、コンタクトガラス２への原稿６の載置基準は原稿
の手前側の端縁をコンタクトガラス２の手前側の縁に合
せる片側基準が多かったが、最近の変倍複写機では縮小
のみならず拡大変倍も要求され、又変倍率の種類も多く
なり、片側基準の場合はレンズを変倍率に応じて光軸方
向に変位させるのみならず、それに直角方向に変位させ
る必要があり、レンズの変位機構が複雑になるので、原
稿載置基準を原稿の走査方向に直角方向の幅の中心線を
コンタクトガラスの中心線に合せて載置する中央基準が
採用されるようになった。この場合はレンズは変倍時に
はその先軸方向に移動させるだけでよく、レンズ変位機
構が比較的簡単になる。Conventionally, the standard for placing the original 6 on the contact glass 2 was often a one-sided standard in which the front edge of the original was aligned with the front edge of the contact glass 2, but recent variable-magnification copiers not only reduce the size but also Enlargement variable power is also required, and the number of types of variable magnification increases, and in the case of one-sided reference, it is necessary to not only displace the lens in the direction of the optical axis according to the variable magnification, but also in a direction perpendicular to it, and the lens Since the displacement mechanism becomes complicated, a center reference has been adopted in which the document is placed so that the center line of the width in the direction perpendicular to the scanning direction of the document is aligned with the center line of the contact glass. In this case, the lens only needs to be moved in the direction of its tip axis when changing magnification, and the lens displacement mechanism becomes relatively simple.

第２図は第１図に示す光学系の光路のスリット方向と光
路の光軸方向を含む甲面の展開図である。FIG. 2 is a developed view of the shell of the optical system shown in FIG. 1, including the slit direction of the optical path and the optical axis direction of the optical path.

前述の如く、縮小時レンズ８は等暗時の位置８から光軸
上を原稿３から遠ざかった位置、例えば８に移動し、拡
大時には逆に原稿面６に近付く位置、例えば８”の位置
に変位する。As mentioned above, when reducing, the lens 8 moves from the position 8 when it is dark to a position farther from the original 3 on the optical axis, for example 8, and when enlarging, it moves to a position closer to the original surface 6, for example 8". Displace.

さて、レンズにはｃｏｓ　４乗則があり、結像面での光
量はレンズ光軸に対する入射角のｅＯ８’に比例して減
少し、画面の周辺光量が低下することが知られている。Now, it is known that lenses have a cos fourth power law, and the amount of light on the imaging plane decreases in proportion to eO8', the incident angle with respect to the optical axis of the lens, and the amount of light at the edges of the screen decreases.

第２図において原稿６上のスリット長ト方向の両端Ａ、
　Ａ’のレンズ８に対する入射角は等暗時の入射角θに
対して縮小時は小さく、拡大時は大きくなる。そこで、
等暗時に感光体１０上のスリット長手方向の光量分布が
フラットになるよう照明ランプ４の長手方向の輝度分布
を一１１区１に比例させて補正すると、この光源で照明
された原稿上のスリットの感光体上での光量分布は第３
図に示す如く、中央部では等暗時と同じであるが、縮小
時には両端に近ずく程光量が多くなり、逆に拡大時には
、両端に近付く程光量が減少する。In FIG. 2, both ends A in the slit length direction on the original 6,
The angle of incidence of A' on the lens 8 is smaller than the angle of incidence θ at constant darkness when the image is reduced, and becomes larger when the image is enlarged. Therefore,
If the luminance distribution in the longitudinal direction of the illumination lamp 4 is corrected in proportion to 111 sections 1 so that the light intensity distribution in the longitudinal direction of the slit on the photoreceptor 10 becomes flat in the dark, the slit on the document illuminated by this light source The light intensity distribution on the photoreceptor is the third
As shown in the figure, the central part is the same as when it is dark, but when zooming out, the closer you get to both ends, the more light there is, and when you enlarge, on the contrary, the closer you get to both ends, the more the light amount decreases.

原稿のフンタクトガラス上への載置基準が片側基準の場
合は、縮小時レンズを原稿から遠ざかる方向に移動させ
ると同時に基準端に近付く方向に移動させるので、基準
端側の画像端部から出た光のレンズへの入射角は等暗時
より減少するが、その反対側の端部から出た光のレンズ
への入射角はあまり変らない。したがって、等暗時に感
光体上ノスリット長手方向の光量分布がフラットになる
ように光源ランプの輝度分布を修正しておけば、感光体
上で中央部から基準端（感光体及び転写紙の通紙基準で
原稿載置基準とは逆になる。）に近づくほど光量が増加
し、これと反対側では光量分布は殆んどフラットになる
。したがって、この照度ムラの補正装置として、特開昭
５５−９１７２８号公報には、原稿面とレンズとの間に
光路の外方の基準端側から光軸に向って光束の一部を遮
蔽する部材を挿入するようにした装置が示されているが
、原稿載置基準が中心線の場合は中央から両端に近付く
につれて光量が増加するので、この方法を利用して補正
することはできない。If the reference for placing the original on the touch glass is one-sided, the lens is moved away from the original and at the same time toward the reference edge during reduction, so that the image will not come out from the edge of the image on the reference edge side. The angle of incidence of the light that enters the lens decreases compared to when it is dark, but the angle of incidence of the light that exits from the opposite end does not change much. Therefore, if the brightness distribution of the light source lamp is corrected so that the light intensity distribution in the longitudinal direction of the noslit on the photoconductor becomes flat in the dark period, it is possible to The light intensity increases as it approaches the reference (which is the opposite of the document placement reference), and the light intensity distribution becomes almost flat on the opposite side. Therefore, as a correction device for this illuminance unevenness, Japanese Patent Application Laid-Open No. 55-91728 proposes a device that blocks a part of the light flux from the reference end side outside the optical path toward the optical axis between the document surface and the lens. A device in which a member is inserted is shown, but if the document placement reference is the center line, the amount of light increases from the center to both ends, so it cannot be corrected using this method.

目　的 本発明は、原稿載置基準が中央基準の変倍複写機におけ
る変倍時の感光体上のスリット長手方向の照度ムラ−の
補正に関する上述の実情にかんがみ、簡単な構成で照明
効率をあまり損なうことなく感光体上の照度ムラを精度
良く補正することのできる装置を提供することを目的と
する。Purpose The present invention has been made in view of the above-mentioned actual situation regarding correction of illuminance unevenness in the longitudinal direction of the slit on the photoreceptor when changing the magnification in a variable magnification copying machine in which the document placement reference is the central reference, and the present invention aims to improve illumination efficiency with a simple configuration. It is an object of the present invention to provide a device that can accurately correct illuminance unevenness on a photoreceptor without causing much damage.

構成 以下、本発明を、実施例を示す図面に基ずいて１！゛（
却１に説明する。Configuration The present invention will be explained below based on the drawings showing the embodiments.゛(
First, let me explain.

本発明は、原稿載置基準が中央基準である少くとも等倍
、縮小可能な変倍複写機の露光光学系の原稿面とレンズ
の間の光路の幅方向の両側に、等暗時には光束を遮蔽せ
ず、倍率がこれより小さくなるに従って、光路の両端部
を遮蔽する量が増加する補正板を機枠に固設し、等暗時
には補正板なしで感光体上のスリット長手方向の照度分
布カー均一になるように補正されており、原稿上のスリ
ットの各位置からの光束の一部が上記補正板により遮蔽
されてレンズ上に落ちる影の面積のレンズの入射瞳の面
積に対する比率が各位置に対して、補正板がな、かった
場合の感光体上の対応する部分の照度ムラの比率に相当
する如く、上記補正板の位置、形状、寸法が定められて
いることを特徴とする。The present invention provides a method of directing a light beam to both sides of the optical path between the document surface and the lens in the width direction of the exposure optical system of a variable magnification copying machine that is capable of at least equal magnification and reduction, in which the document placement reference is the central reference. A correction plate is fixed to the frame of the machine that blocks the amount of light at both ends of the optical path increasing as the magnification becomes smaller. A portion of the light flux from each position of the slit on the document is blocked by the correction plate, and the ratio of the area of the shadow that falls on the lens to the area of the entrance pupil of the lens is adjusted to be uniform. The position, shape, and dimensions of the correction plate are determined so as to correspond to the ratio of illuminance unevenness on the corresponding part of the photoreceptor when the correction plate is missing. .

第４図は本発明を等倍と縮小、拡大各１種の倍率の変倍
複写機に適用した実施例を示す図面であって第２図にお
けるレンズ８の等暗時、縮小時及び拡大時の位置８．８
’、８”及びそれらの位置にあるレンズに対する原稿上
のスリットの最外側端の点Ａ、Ａ’からの光線が示され
ている。図示せぬ原稿面とレンズ８との間には、光路の
両側に補正板１１が機枠に固設されている。この補正板
１１は拡大時及び等暗時の８“、８の位置にあるレンズ
に対する光束を全く遮蔽せず、縮小時８′の位置にある
レンズに対する光束は図中にハツチングで社範囲の光束
を遮蔽するようになっている。FIG. 4 is a drawing showing an embodiment in which the present invention is applied to a variable magnification copying machine with one type of magnification each of equal magnification, reduction, and enlargement, in which the lens 8 in FIG. position 8.8
', 8'' and the lenses at those positions, light rays from points A and A' at the outermost ends of the slits on the original are shown. A correction plate 11 is fixed to the machine frame on both sides of the frame.This correction plate 11 does not block the light flux to the lens at 8" and 8 when zooming in and at constant darkness, and does not block the light flux to the lens at 8' when zooming out. The light beam directed toward the lens located at this position is shaded by hatching in the diagram to block the light beam within the area.

等暗時には原稿からの光束は補正板１１によって全く遮
蔽されないが、ｃｏｓ’乗則による感光体上のスリット
長手方向の照度ムラを補正するために例えば原稿照明ラ
ンプの輝度分布を両端部が中央部より大きくされている
。あるいはスリット幅規制部材を設はスリット長手方向
に幅を変えてもよい。これにより補正板がない場合の感
光体上の等倍、縮小、拡大時の夫々のスリット長手方向
の照度分布は夫々第３図に示す曲線の如くなり、等暗時
にはフラットで拡大時には両端部かや＼低下し、縮小時
には両端部の照灯が中央部より大きくなる。When it is dark, the light flux from the original is not blocked at all by the correction plate 11, but in order to correct the unevenness of illuminance in the longitudinal direction of the slit on the photoreceptor due to the cos' power law, for example, the brightness distribution of the original illumination lamp is changed so that both ends are in the center. It has been made larger. Alternatively, a slit width regulating member may be provided to vary the width in the longitudinal direction of the slit. As a result, the illuminance distribution in the longitudinal direction of the slit on the photoreceptor when there is no correction plate at equal magnification, reduction, and enlargement will be as shown in the curves shown in Figure 3, and it will be flat when it is dark and at both ends when it is enlarged. and ＼ decreases, and when zooming out, the illumination at both ends becomes larger than the center.

この装置の作用を第５図により説明すると、縮小時原稿
上のスリットの最外側の点Ａから出た光束の一部は補正
板１１により遮光されてレンズ上にＷａの幅の形を落す
。Ａ点より中心に近づくにつれてその点からの光束のう
ち補正板１１に遮光される光束のレンズ８への入射角は
小さくなってゆき、レンズ上に落ちる影の幅は小さくな
り、Ｂ点では補正板１１の一部しか光束に掛らな（・の
で影の幅ｗｂは更に小さくなる。このようにして、原稿
上のスリットの両端部に近づく程、影の幅が大きくなり
、中央部のある範囲では影がなくなる。The operation of this device will be explained with reference to FIG. 5. During reduction, a part of the light beam emitted from the outermost point A of the slit on the document is blocked by the correction plate 11 and falls on the lens in the shape of width Wa. As the point approaches the center from point A, the angle of incidence of the light beam from that point that is blocked by the correction plate 11 on the lens 8 becomes smaller, the width of the shadow falling on the lens becomes smaller, and at point B the correction becomes smaller. Since only a part of the plate 11 is covered by the light beam, the width of the shadow wb becomes even smaller.In this way, the closer you get to both ends of the slit on the document, the wider the shadow becomes; There are no shadows within the range.

このようにレンズ上での影の面積のレンズの入射瞳の面
積に対する比率だけ感光体上のスリットの対応する点に
達する光量は減少するので、レンズ上の影の面積のレン
ズの入射瞳の面積に対する比率が縮小時の感光体上のス
リット長手方向の照度ムラの比率に相当するように補正
板１１の位置、形状、寸法をあらかじめ決めておけば感
光体上のスリット長手方向の照度ムラはこれによって補
正することができる。In this way, the amount of light reaching the corresponding point of the slit on the photoreceptor decreases by the ratio of the area of the shadow on the lens to the area of the entrance pupil of the lens, so the area of the entrance pupil of the lens is the area of the shadow on the lens. If the position, shape, and dimensions of the correction plate 11 are determined in advance so that the ratio of the ratio to that of the illuminance in the longitudinal direction of the slit on the photoconductor corresponds to the ratio of the illuminance unevenness in the longitudinal direction of the slit on the photoconductor, the illuminance unevenness in the longitudinal direction of the slit on the photoconductor can be reduced as follows. It can be corrected by

上記の実施例では、光源の長手方向輝度分布を等暗時に
感光体上の照度分布がフラットになる如く補正されてい
るので縮小時には上記の補正板により補正されるが、拡
大時には両端部の光量不足は補正されない。しかし、最
も使用頻度の多い等暗時に光束が遮光されないので、照
明効率が高い。In the above embodiment, the luminance distribution in the longitudinal direction of the light source is corrected so that the illuminance distribution on the photoreceptor becomes flat when it is dark, so it is corrected by the above correction plate when reducing, but when enlarging, the light intensity at both ends is corrected. Deficiencies are not corrected. However, since the luminous flux is not blocked during dark times, which is the most frequently used time, the lighting efficiency is high.

なお、第１図に示したような光学系でレンズを移動させ
て変倍複写を行なう場合は、スリット短手方向（走査方
向）のスリット幅規制部材を感光体の近傍に設けた場合
は倍率によって露光量が変化し好ましくない。原稿の近
傍の光路にスリット幅規制部材を設けた場合は、原稿照
度とスリット幅の積が一定になりｍ倍の倍率で感光体上
に結像すれば単位面積当り照度は１／ｒｒｌのになる。Note that when performing variable magnification copying by moving the lens in an optical system as shown in Figure 1, if a slit width regulating member in the slit width direction (scanning direction) is provided near the photoreceptor, the magnification will change. The amount of exposure changes depending on the amount of light, which is undesirable. If a slit width regulating member is provided in the optical path near the original, the product of the original illuminance and the slit width will be constant, and if an image is formed on the photoreceptor at a magnification of m, the illuminance per unit area will be 1/rrl. Become.

しかしこの場合は走査速度も１んこするので、相殺して
露光量は倍率ｍに無関係に一定になり好都合である。However, in this case, the scanning speed also decreases by 1, which is advantageous because it offsets the exposure amount and makes it constant regardless of the magnification m.

しかし、原稿と第１ミラーとの間は狭く、光源ランプと
第１ミラーとを担持するスキャナーに更にスリット幅規
制部材を設けることは構造上かなり窺屈になる。そこで
第１ミラーの反射面の幅をスリット幅に一致させること
によりスリット幅規制部材に兼用させるのがよい。However, the space between the document and the first mirror is narrow, and it would be quite complicated from a structural standpoint to further provide a slit width regulating member to the scanner that supports the light source lamp and the first mirror. Therefore, it is preferable to make the width of the reflective surface of the first mirror match the slit width so that it can also be used as a slit width regulating member.

効　果 以上の如く、本発明によれば簡１１′Ｌな構成で等倍か
ら縮小にわたって感光体上の照度ムラを容易にかつ精度
良く補正することができ、調整も容易で　−ある。又最
も使用頻度の高い等暗時には光束が遮蔽されないので照
明効率が低下することもなく省エネルギーにも効果があ
る。Effects As described above, according to the present invention, it is possible to easily and accurately correct illuminance unevenness on the photoreceptor from normal magnification to reduced magnification with a simple configuration, and adjustment is also easy. In addition, since the light beam is not blocked during dark times, such as when it is used most frequently, the illumination efficiency does not decrease and it is effective in saving energy.

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

第１図は本発明の適用される光学系の一例を示す縦断面
図、第２図はその光路を展開して示す平面図、第３図は
その光学系における感光体上のスリット長手方向の縮小
、等倍、拡大時の照度分布の一例を示す曲線図、第４図
は本発明の実施例を示す平面図、第５図はその作用を説
明する図式図である。 ２・・・コンタクトガラス　３・・・原稿８・・・レン
ズ　１１・・・補正板 「二′　□ 第４図 ３ 第５図！Fig. 1 is a longitudinal sectional view showing an example of an optical system to which the present invention is applied, Fig. 2 is a plan view showing the optical path expanded, and Fig. 3 is a longitudinal sectional view of the slit on the photoreceptor in the optical system. FIG. 4 is a curve diagram showing an example of illuminance distribution during reduction, same magnification, and enlargement, FIG. 4 is a plan view showing an embodiment of the present invention, and FIG. 5 is a schematic diagram illustrating its operation. 2...Contact glass 3...Original 8...Lens 11...Correction plate "2' □ Fig. 4 3 Fig. 5!

Claims (1)

【特許請求の範囲】[Claims] コンタクトガラス上への原稿載置基準が原稿走査方向に
対して直角方向の幅の中央であり、露光々学系のレンズ
を光路の光軸方向に移動させて変倍を行なうスリット露
光方式の変倍複写機におけるスリット長手方向の感光体
照度ムラ補正装置において、原稿面とレンズの間の光路
の幅方向の両側に、等暗時の光束を遮蔽せず、倍率がこ
れより小さくなるにしたがって光路の端部を遮蔽する量
が漸次増加する補正板を機枠に固設し、等暗時には補正
板なしで感光体上のスリット長手方向の照度分布が均一
になるように補正されており、原稿上のスリットの各位
置からの光束の一部が上記補正板により遮蔽されてレン
ズ上に落る影の面積のレンズの入射瞳の面積に対する比
率が、各縮小倍率に対して補正板がなかった場合の感光
体上の対応する部分の照度ムラの比率に相当する如く、
上記補正板の位置、形状、寸法が定められていることを
特徴とする照度ムラ補正装置。A change in the slit exposure method in which the reference for placing the original on the contact glass is the center of the width in the direction perpendicular to the original scanning direction, and the magnification is changed by moving the exposure lens in the optical axis direction of the optical path. In a photoconductor illuminance unevenness correction device in the longitudinal direction of the slit in a magnification copying machine, the light beam is not blocked on both sides of the optical path between the document surface and the lens in the width direction, and as the magnification becomes smaller, the optical path A correction plate that gradually increases the amount of shielding of the edges of the photoreceptor is fixed to the machine frame, and when it is dark, the illuminance distribution in the longitudinal direction of the slit on the photoreceptor is corrected to be uniform without using the correction plate. A portion of the luminous flux from each position of the upper slit is blocked by the correction plate, and the ratio of the area of the shadow that falls on the lens to the area of the entrance pupil of the lens is determined by the fact that there is no correction plate for each reduction magnification. This corresponds to the ratio of illuminance unevenness on the corresponding part of the photoreceptor in the case of
An illuminance unevenness correction device characterized in that the position, shape, and dimensions of the correction plate are determined.