JPH01274560A - Photoelectric converter - Google Patents
Photoelectric converterInfo
- Publication number
- JPH01274560A JPH01274560A JP63104570A JP10457088A JPH01274560A JP H01274560 A JPH01274560 A JP H01274560A JP 63104570 A JP63104570 A JP 63104570A JP 10457088 A JP10457088 A JP 10457088A JP H01274560 A JPH01274560 A JP H01274560A
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- JP
- Japan
- Prior art keywords
- light source
- photoelectric conversion
- original
- entire width
- output signal
- Prior art date
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- 238000006243 chemical reaction Methods 0.000 claims abstract description 28
- 238000003384 imaging method Methods 0.000 claims description 8
- 230000003287 optical effect Effects 0.000 claims description 2
- 238000003705 background correction Methods 0.000 abstract description 9
- 230000006866 deterioration Effects 0.000 abstract description 7
- 230000001678 irradiating effect Effects 0.000 abstract 2
- 235000014676 Phragmites communis Nutrition 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
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Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、直線上に配列された光電変換素子群と、読み
取るべき原稿の像を前記光電変換素子群の受光面に結像
させる結像光学系と、前記原稿の読取点を全幅に渡って
照射する光源とを有する光電変換装置に関する。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a group of photoelectric conversion elements arranged in a straight line and an imaging optical system that forms an image of a document to be read on a light receiving surface of the group of photoelectric conversion elements. and a light source that irradiates the entire width of the reading point of the document.
従来の技術
従来この種の装置は、第５図に示すように、直線上に配
列された光電変換素子群１と、原稿２の像を光電変換素
子群１に結像させる結像レンズ３と、原稿２の読取点を
全幅に渡って照射するだめの螢光灯からなる光源４等を
有しており、光源４が原稿２を照射し、その反射光を結
像レンズ３が光電変換素子群Ｉの受光面上に結像させ、
光電変換素子群１が入射光量に応じた電気信号を出力し
ている。この系において、螢光灯の長手方向の輝度むら
、結像レンズ３による周辺光量低下、或いは光電変換素
子群１の感度ばらつきなどが原因で、シェーディング歪
みが生じるため、光電変換素子群１により電気信号に変
換された信号に、成る補正係数を掛けてシェーディング
補正を行っている。2. Description of the Related Art Conventionally, as shown in FIG. 5, this type of apparatus includes a group of photoelectric conversion elements 1 arranged in a straight line, an imaging lens 3 that forms an image of a document 2 on the group of photoelectric conversion elements 1, and , has a light source 4 made of a fluorescent lamp that irradiates the entire width of the reading point of the original 2, etc. The light source 4 irradiates the original 2, and the imaging lens 3 converts the reflected light into a photoelectric conversion element. An image is formed on the light-receiving surface of group I,
A photoelectric conversion element group 1 outputs an electrical signal according to the amount of incident light. In this system, shading distortion occurs due to uneven brightness in the longitudinal direction of the fluorescent lamp, a decrease in peripheral light intensity due to the imaging lens 3, or variations in sensitivity of the photoelectric conversion element group 1. Shading correction is performed by multiplying the converted signal by the following correction coefficient.
ここで、シェーディング補正を行う補正係数は、原稿読
取開始時の光電変換素子群１の出力分布に基づいて定め
、短くとも一原稿読み取りの間は、その補正係数により
シェーディング補正を行っていた。例えば、第６図にお
いて、全白の原稿読取開始時の光電変換素子群１の出力
信号波形が（ａ）に符号５で示すように分布している時
に、補正後の出力波形が（ｂ）に符号６で示すように一
定になるように、補正係数を定め、以後はその補正係数
を用いてシェーディング補正を行っていた。Here, the correction coefficient for performing shading correction is determined based on the output distribution of the photoelectric conversion element group 1 at the start of document reading, and the shading correction is performed using the correction coefficient for at least one document reading. For example, in FIG. 6, when the output signal waveform of the photoelectric conversion element group 1 at the start of reading an all-white document is distributed as shown in (a) by reference numeral 5, the output waveform after correction is as shown in (b). A correction coefficient was determined so as to be constant as shown by reference numeral 6, and thereafter the shading correction was performed using the correction coefficient.
発明が解決しようとする課題
しかし、かかる構成によれば、原稿読取中に、白が黒み
を帯びてくるなど、画質劣化が生じるという問題点があ
った。Problems to be Solved by the Invention However, with this configuration, there is a problem in that image quality deteriorates, such as whites becoming darker during document reading.
本発明者らが上述問題の原因を検討した結果、これらが
光源である螢光灯の経時的な配光分布の変化によって生
じていることを見出した。すなわち、螢光灯は点灯直後
から数分にわたり、発光が不安定状態にあり、配光分布
に変化が生じ、シェーディング歪みが時々刻々変化する
が、従来は一定の補正係数により補正を行っているため
、正しい補正ができず、画質劣化が生じていた。例えば
、第６図において、（ａ）に示す全白の原稿読取開始時
の光電変換素子群１の出力信号波形５から、（ｂ）に示
す補正後の信号波形６を得るように補正係数を定めても
、読取継続中に、全白の原稿読取の出カ場ｔａｉｊｒ（
ｃ）に符号７で示すように変化してしまい、これを前記
の補正係数で補正した出力信号波形は、（ａ）に符号８
で示すように変化し、正しい信号に対して斜線部分９の
誤差が生じ、画質劣化をもたらしていた。この現象は、
特に低温時に顕著に生じていた。As a result of examining the causes of the above-mentioned problems, the inventors of the present invention found that these problems are caused by changes in the light distribution over time of the fluorescent lamp that is the light source. In other words, for several minutes immediately after the fluorescent lamp is turned on, the light emission is unstable, the light distribution changes, and the shading distortion changes from moment to moment, but conventionally this is corrected using a fixed correction coefficient. Therefore, correct correction could not be made and image quality deteriorated. For example, in FIG. 6, the correction coefficient is changed to obtain the corrected signal waveform 6 shown in (b) from the output signal waveform 5 of the photoelectric conversion element group 1 at the start of reading an all-white document shown in (a). Even if you set the output field taijr (
(c) changes as shown by code 7, and the output signal waveform corrected by the above correction coefficient is shown in (a) by code 8.
The error in the shaded area 9 occurs with respect to the correct signal, resulting in deterioration of image quality. This phenomenon is
This was particularly noticeable at low temperatures.
なお、螢光灯の発光分布の変化を抑えるため、ヒーター
を用いて管壁温度を制御する方法が考えられるが、配光
分布の変化に対して完全な解決索にはならない。Note that in order to suppress changes in the light emission distribution of a fluorescent lamp, a method of controlling the tube wall temperature using a heater can be considered, but this is not a complete solution to changes in the light distribution.
まだ、シェーディング歪みを補正するため、螢光灯の両
端部分に補助光源を設けることが特開昭５４−４００２
３号公報に提案されているが、この補助光源は、螢光灯
の両端の光量不足を補うだめのものであって螢光灯の配
光分布の変化を抑えるものではないので、シェーディン
グ歪みの経時変化に伴う画質劣化を防止できなかった。It is still necessary to provide auxiliary light sources at both ends of the fluorescent lamp in order to correct shading distortion, as disclosed in Japanese Patent Application Laid-Open No. 54-4002.
Although proposed in Publication No. 3, this auxiliary light source is only intended to compensate for the lack of light intensity at both ends of the fluorescent lamp, and is not intended to suppress changes in the light distribution of the fluorescent lamp, so it does not cause shading distortion. It was not possible to prevent image quality deterioration due to changes over time.
本発明は、上述の問題点に鑑みて為されたもので、螢光
灯の配光分布の影響を低減することができる光電変換装
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 an object of the present invention is to provide a photoelectric conversion device that can reduce the influence of the light distribution of a fluorescent lamp.
課題を解決するだめの手段
本発明は上述の問題点を解決するため、経時的な配光分
布変化が非常に小さく無視しうる光源、例えば、発光ダ
イオードアレイ（以下ＬＥＤアレイという）を、配光分
布変化の大きい螢光灯の補助光源として用い、主光源で
ある螢光灯で照射した原稿読取点の全幅を、補助光源で
照射するという構成を備えたものである。Means for Solving the Problems In order to solve the above-mentioned problems, the present invention uses a light source whose light distribution changes over time are very small and can be ignored, such as a light emitting diode array (hereinafter referred to as an LED array). It is used as an auxiliary light source for a fluorescent lamp with a large distribution change, and has a configuration in which the auxiliary light source irradiates the entire width of the document reading point illuminated by the fluorescent lamp, which is the main light source.
作用
本発明は上述の構成によって、原稿読取点の全幅が主光
源と補助光源とで照射されるため、原稿の反射光に占め
る主光源からの光量の割合が低下し、それによって全体
に対する主光源の配光分布変化の影響が低減され、画質
劣化防止が可能となる。“
実施例
以下、本発明の詳細な説明する。Effect of the Invention With the above-described configuration, the present invention illuminates the entire width of the document reading point with the main light source and the auxiliary light source, so the ratio of the amount of light from the main light source to the light reflected from the document decreases, thereby reducing the amount of light from the main light source relative to the entire document. The influence of changes in light distribution is reduced, making it possible to prevent image quality deterioration. “Examples The present invention will be explained in detail below.
第１図は本発明の一実施例による光電変換装置の概略構
成を示す斜視図であり、第５図に示す部材と同一の部材
には同一符号を付けて示している。FIG. 1 is a perspective view showing a schematic configuration of a photoelectric conversion device according to an embodiment of the present invention, and the same members as those shown in FIG. 5 are designated by the same reference numerals.
第１図において、１は直線上に配列された光電変換素子
群、２は読み取るべき原稿、３は原稿２の像を光電変換
素子群１に結像させる結像レンズ、４は原稿２の読取点
全幅を照射する螢光灯からなる主光源である。この主光
源４の近傍に、主光源に平行に補助光源１０が設けられ
ている。この補助光源１０は、経時的な発光分布変化の
小さい光源、例えばＬＥＤアレイで構成され、読取点全
幅を照射するように配置されている。光電変換素子群１
には、シェーディング補正機能を備えた制御回路（図示
せず）が接続されている。In FIG. 1, 1 is a group of photoelectric conversion elements arranged in a straight line, 2 is an original to be read, 3 is an imaging lens that forms an image of the original 2 on the photoelectric conversion element group 1, and 4 is a lens for reading the original 2. The main light source consists of a fluorescent lamp that illuminates the entire width of the point. An auxiliary light source 10 is provided near the main light source 4 and parallel to the main light source. The auxiliary light source 10 is composed of a light source whose emission distribution changes little over time, such as an LED array, and is arranged so as to illuminate the entire width of the reading point. Photoelectric conversion element group 1
A control circuit (not shown) having a shading correction function is connected to.
以上のように構成された光電変換装置について、以下そ
の動作を説明する。主光源４及び補助光源１０が原稿２
を照射し、その反射光が結像レンズ３により光電変換素
子群１の受光面に結像され、光電変換素子群１により電
気出力信号に変換され、初期の出力信号によってシェー
ディング補正係数が定められ、短くとも一枚の原移読み
取りの間は、その補正係数によりシＬ・−ディング補正
が行われ、補正後の信号が画像信号としで出力される。The operation of the photoelectric conversion device configured as described above will be described below. The main light source 4 and the auxiliary light source 10 are the original 2
The reflected light is imaged by the imaging lens 3 on the light-receiving surface of the photoelectric conversion element group 1, and is converted into an electrical output signal by the photoelectric conversion element group 1. A shading correction coefficient is determined based on the initial output signal. During the reading of at least one original sheet, siding correction is performed using the correction coefficient, and the corrected signal is output as an image signal.
第２図はこの実施例における補正前の出力信号波形と補
正後の出力信号波形との例を示すものであり、（ａ）の
符号１１は原稿読取開始時に全白を読み取った時の補正
前の出力信号波形である。この出力信号の大きさは主光
源からの照射光量と補助光源からの照射光量の和に比例
しており、斜線で示す領域１２は補助光源の光量によっ
て決まる出力部分を示している。（ｂ）の符号１３は補
正後の出力信号即ち画像信号波形を示すものであり、前
記した出力信号波形１１が出力信号波形１３になるよう
に、補正係数が定められ、以後、その補正係数によるシ
ェーディング補正が行われる。ところで、主光源である
螢光灯の配光分布は経時的に変化するので、成る時間経
過後には同じ全白原稿を読み取っても、光電変換素子群
の出力は第２図（ｃ）に符号１４で示す信号波形となり
、出力信号波形１１とは異なって来る場合があり、これ
を先に定めた補正係数で補正すると、（ｄ）に符号１５
で示す出力信号波形となり、正規の波形に対して斜線１
６で示す量だけ変化が生じてくる。しかしながら、補正
前の出力信号波形１４は、経時的な配光分布変化を無視
しうる補助光源による出力部分１２を含んでいるため、
第６図に示したように螢光灯のみを使用した時の出力信
号波形７に比べて、全体としての変化率が小さくなって
おり、シェーディング歪みの変動が小さくなっている。FIG. 2 shows an example of the output signal waveform before correction and the output signal waveform after correction in this embodiment, and the reference numeral 11 in (a) indicates the waveform before correction when all white is read at the start of document reading. This is the output signal waveform of The magnitude of this output signal is proportional to the sum of the amount of light irradiated from the main light source and the amount of light irradiated from the auxiliary light source, and the shaded area 12 indicates the output portion determined by the amount of light from the auxiliary light source. The reference numeral 13 in (b) indicates the corrected output signal, that is, the image signal waveform. A correction coefficient is determined so that the above-mentioned output signal waveform 11 becomes the output signal waveform 13. Shading correction is performed. By the way, the light distribution of the fluorescent lamp, which is the main light source, changes over time, so even if the same all-white original is read after a certain period of time, the output of the photoelectric conversion element group will change as shown in Figure 2 (c). 14, which may be different from the output signal waveform 11. If this is corrected using the previously determined correction coefficient, the signal waveform 15 will be shown in (d).
The output signal waveform is shown as , and the diagonal line 1 is
A change occurs by the amount indicated by 6. However, since the output signal waveform 14 before correction includes an output portion 12 caused by the auxiliary light source where changes in light distribution over time can be ignored,
As shown in FIG. 6, compared to the output signal waveform 7 when only a fluorescent lamp is used, the overall rate of change is smaller, and the fluctuation of shading distortion is smaller.
これによって、補正後の出力波形の誤差量（斜線Ｉ６の
大きさ）が、第６図の出力波形の誤差量（斜線９の大き
さ）に比べて小さくなり、画質劣化が防止される。As a result, the error amount of the corrected output waveform (the size of the diagonal line I6) becomes smaller than the error amount of the output waveform (the size of the diagonal line 9) in FIG. 6, and image quality deterioration is prevented.
第３図は本発明の他の実施例を示すものである。FIG. 3 shows another embodiment of the invention.
この実施例では主光源４を構成する螢光灯に、管壁温度
を検知するサーマルリードスイッチ１８を取付け、その
出力信号で補助光源１０を制御するように構成したもの
であり、他の構成は、第１図の実施例と同様である。本
実施例では、低温時に螢光灯の配光分布の変動が特に大
きいので、低温時をサーマルリードスイッチ１８で検出
し、その時にのみ補助光源１０を点灯するか或いは補助
光源１０の光量を増すことにより、螢光灯の配光分布変
動の影響を小さくするものである。In this embodiment, a thermal reed switch 18 for detecting the tube wall temperature is attached to the fluorescent lamp constituting the main light source 4, and the auxiliary light source 10 is controlled by the output signal of the thermal reed switch 18. , similar to the embodiment of FIG. In this embodiment, since the variation in the light distribution of the fluorescent lamp is particularly large at low temperatures, the thermal reed switch 18 detects low temperatures, and only at that time the auxiliary light source 10 is turned on or the light intensity of the auxiliary light source 10 is increased. This reduces the influence of variations in the light distribution of the fluorescent lamp.
第４図は本発明の更に他の実施例を示すものである。こ
の実施例では、主光源４を構成する螢光灯の光量を検出
するフォトセンサ１９を設け、その検出信号を補助光源
１００制御回路Ｉに入力するように構成したものであり
、他の構成は、第１図の実施例と同様である。本実施例
では、低光量時に螢光灯の配光分布の変動が特に大きい
ので、螢光灯の低光量時をフォトセンサ１９で検出し、
その時にのみ補助光源１０を点灯するか或いは補助光源
１０の光量を増すことにより、螢光灯の配光分布変動の
影響を小さくするものである。FIG. 4 shows still another embodiment of the present invention. In this embodiment, a photosensor 19 is provided to detect the amount of light from a fluorescent lamp constituting the main light source 4, and the detection signal is input to the control circuit I of the auxiliary light source 100. , similar to the embodiment of FIG. In this embodiment, since the variation in the light distribution of the fluorescent lamp is particularly large when the light intensity is low, the photosensor 19 detects the low light intensity of the fluorescent lamp,
By turning on the auxiliary light source 10 only at that time or increasing the amount of light from the auxiliary light source 10, the influence of variations in the light distribution of the fluorescent lamp is reduced.
発明の効果
以上の説明から明らかなように、本発明は、配光分布変
化が非常に小さい光源を、配光分布変化の大きい螢光灯
で構成された主光源に対する補助光源として使用するこ
とによって、全体としての配光分布変化、即ちシェーデ
ィング歪みの変動を低減することができ、画質劣化を防
止することができるという効果を有するものである。Effects of the Invention As is clear from the above description, the present invention has the advantage of using a light source with a very small change in light distribution as an auxiliary light source for a main light source composed of a fluorescent lamp with a large change in light distribution. This has the effect that changes in the overall light distribution, that is, fluctuations in shading distortion, can be reduced, and image quality deterioration can be prevented.
第１図は本発明の一実施例による光電変換装置の概略斜
視図、第２図（ａ）、（ｂ）、（ｃ）、（ｄ）はその装
置における信号波形を示す図、第３図、第４図はそれぞ
れ本発明の他の実施例による光電変換装置の概略斜視図
、第５図は従来の光電変換装置の概略斜視図、第６図（
ａ）、（ｂ）、（ｃ）、（ｄ）はその装置における信号
波形を示す図である。
■・・・光電変換素子群、２・・・原稿、３・・・結像
レンズ、４・・・主光源（螢光灯）、１０・・・補助光
源、１８・・・サーマルリードスイッチ、１９・・・フ
ォトセンサ、加・・・制御回路。
代理人の氏名 弁理士 中 尾 敏 男 ほか１名第１
図
１１．２ δ
第３図
Ｂ ５ 図
第６０FIG. 1 is a schematic perspective view of a photoelectric conversion device according to an embodiment of the present invention, FIGS. 2(a), (b), (c), and (d) are diagrams showing signal waveforms in the device, and FIG. 3 , FIG. 4 is a schematic perspective view of a photoelectric conversion device according to another embodiment of the present invention, FIG. 5 is a schematic perspective view of a conventional photoelectric conversion device, and FIG.
a), (b), (c), and (d) are diagrams showing signal waveforms in the device. ■...Photoelectric conversion element group, 2... Original, 3... Imaging lens, 4... Main light source (fluorescent lamp), 10... Auxiliary light source, 18... Thermal reed switch, 19...Photo sensor, control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 11.2 δ Figure 3B 5 Figure 60
Claims (1)
稿の像を前記光電変換素子群の受光面に結像させる結像
光学系と、前記原稿の読取点を全幅に渡って照射する螢
光灯からなる主光源と、前記原稿の読取点を全幅に渡っ
て照射する発光分布変化の少ない補助光源とを有するこ
とを特徴とする光電変換装置。A group of photoelectric conversion elements arranged in a straight line, an imaging optical system that forms an image of a document to be read on a light-receiving surface of the group of photoelectric conversion elements, and a fluorescent light that illuminates the entire width of the reading point of the document. A photoelectric conversion device characterized by having a main light source consisting of a lamp, and an auxiliary light source that illuminates the reading point of the document over the entire width and whose emission distribution does not change much.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63104570A JPH01274560A (en) | 1988-04-27 | 1988-04-27 | Photoelectric converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63104570A JPH01274560A (en) | 1988-04-27 | 1988-04-27 | Photoelectric converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01274560A true JPH01274560A (en) | 1989-11-02 |
Family
ID=14384103
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63104570A Pending JPH01274560A (en) | 1988-04-27 | 1988-04-27 | Photoelectric converter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01274560A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006060407A (en) * | 2004-08-18 | 2006-03-02 | Ricoh Co Ltd | Light source unit, image reader, and image forming apparatus |
-
1988
- 1988-04-27 JP JP63104570A patent/JPH01274560A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006060407A (en) * | 2004-08-18 | 2006-03-02 | Ricoh Co Ltd | Light source unit, image reader, and image forming apparatus |
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