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JP4362745B2 - Paper identification sensor - Google Patents

Paper identification sensor Download PDF

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Publication number
JP4362745B2
JP4362745B2 JP37128599A JP37128599A JP4362745B2 JP 4362745 B2 JP4362745 B2 JP 4362745B2 JP 37128599 A JP37128599 A JP 37128599A JP 37128599 A JP37128599 A JP 37128599A JP 4362745 B2 JP4362745 B2 JP 4362745B2
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Japan
Prior art keywords
paper
light
light emitting
emitting element
receiving element
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JP37128599A
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Japanese (ja)
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JP2001180843A (en
Inventor
正巳 韮澤
賢次 佐賀
誉大 立花
宏信 木内
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Nippon Aleph Corp
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Nippon Aleph Corp
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Description

【0001】
【発明の属する技術分野】
この発明は、プリンタ、電子写真複写機などの印刷装置において、収納状態または給送状態にある各種用紙の光学的反射特性の違いにより、OHPシート、光沢紙等の特殊用紙と普通紙とを識別する用紙識別センサに関するものである。
【0002】
【従来の技術】
プリンタ、電子写真複写機などの印刷装置において、印刷物の利用目的の多様化等に対応してOHPシート、光沢紙等の普通紙以外の用紙が提供されている。これらの用紙は表面処理などの加工が異なることから、各々に適した印字条件や用紙搬送条件の切換えが必要となる。
【0003】
このため印刷装置等にセットされた用紙の種類を判別するための技術が種々開発されている。これらの技術は大半が光学式センサを用いたものであり、たとえば、特開平2−56375号公報、特開平6−56313号公報、特開平10−198174号および特開平10−198093号公報等に記載されたものが知られている。いづれの技術においても発光素子と受光素子を1個または2個組み合わせた用紙種類識別装置となっている。
【0004】
これらの従来装置における用紙種類の識別方法では、発光素子から照射された光が用紙表面で反射されて受光素子で受光される過程において、用紙表面で反射される反射光を正反射光と乱反射光とに区分する。そして正反射光として得られた値と予め設定された基準値との比較または正反射光と乱反射光として得られたそれぞれの値と予め設定されたそれぞれの基準値と比較することによって行われる。
【0005】
ところで、従来の用紙識別センサにおいては、その主な識別の対象がOHPシートと普通紙との識別であった。両者では材質も異なることから表面の反射率においても極めて大きな差異があり、したがって比較的容易に識別可能である。
【0006】
【発明が解決しようとする課題】
しかしながら、従来の用紙種類識別センサにおいては、発光素子が照射した光が用紙表面で反射し、その反射光は受光素子によって受光される。そして反射光の強度によって変化する受光素子の出力値と、予め設定された基準値とを比較することにより識別が行われている。
【0007】
このため、得られる出力値の変化量(ダイナミックレンジ)は必然的に小さくならざるを得ず、また実際に使用される発光素子および受光素子のレンズ部形状の光学的バラツキ、光半導体としての感度のバラツキ、さらにその素子を用紙種類識別センサとして組み立てた際の組付けのバラツキがある。これらを考慮すると、受光素子で得られる反射光の受光強度の変化にともなう出力値の変化量を適正に確保するのは極めて困難である。この出力値と絶対値である基準値を比較することはノイズマージンを十分に得られない結果となる。
【0008】
このため、用紙識別センサを製造する場合においては、使用する素子の性能バラツキを抑えるための選別が必要となり、生産性の悪化、コストアップの要因となっていた。さらにプリンタ、電子写真複写機などの印刷装置におけるカラー化の普及に伴い、デジタル画像のカラー印刷の要求とともにOHPシート以外に、高品質な印刷を得る目的で光沢紙が使用されるようになっている。光沢紙と普通紙との反射率の差は、OHPシートと普通紙との差ほど大きくなく、受光素子で得られる反射光強度の差による出力値の変動量はより小さくなる。従来技術における受光素子の出力値と設定値とを比較する手段では、用紙種類の正確な識別が実質的に困難となった。
【0009】
また、すべての発光素子は一般に、使用時間の経過とともにその出力は減光する。従来技術のように発光素子が照射した光の用紙からの反射光を受光素子で受光し、その出力値の絶対値を比較判定するだけでは各種用紙の識別が正しく行われない可能性がある。
【0010】
本発明はこのような問題を解消するためになされたものであり、安価にかつ正確に安定して用紙種類を識別し得る用紙識別センサを提供するものである。
【0011】
【課題を解決するための手段】
この発明は、識別すべき用紙に照射された光の反射特性に基づき、用紙の種類を識別するようにした用紙識別センサであって、識別すべき用紙の法線に対して45°〜60°の角度位置で配置され、広がりを以って光を照射する発光素子と、正反射成分の多い角度位置であって上記発光素子の対向側で該発光素子と同一角度位置に配置された第1の受光素子と、混合反射成分の多い角度位置であって上記発光素子の対向側で上記第1の受光素子のほぼ1/2となる角度位置に配置された第2の受光素子と、を備え、上記発光素子から光を照射し、上記第1の受光素子の出力電圧Vと上記第2の受光素子の出力電圧Vとを大小比較して、V−V<0であれば普通紙と識別し、V−V>0であれば光沢紙またはOHPシートと識別することを特徴とする。
【0012】
上記構成において、識別すべき用紙の上に遮光板が配置され、用紙からの反射光の面積を一定範囲に限定することが好ましい。
【0015】
この発明によれば、種類を識別しようとする用紙に光を照射する発光素子と用紙からの反射光を受光する2つの受光素子を備えている。そして、発光素子の法線に対する配置角度を45°以上とし、第1の受光素子を用紙からの正反射成分の多い位置となる発光素子と対向する側に同一角度で配置し、第2の受光素子を混合反射成分の多い位置となる第1の受光素子の配置角度の半分となる角度の近傍に配置する。
【0016】
上記構成において、第1の受光素子の出力値(V1 )と第2の受光素子の出力値(V2 )を各種用紙について測定すると、普通紙ではV1 <V2 である。一方OHPシートや光沢専用紙においてはV1 >V2 である。よってV1 とV2 を大小比較することにより、発光素子の発光強度のバラツキ、受光素子の感度のバラツキおよび用紙種類識別センサとして組み立てた際の組付けのバラツキに影響されないで用紙種別を正確に判定することができる。
【0017】
【発明の実施の形態】
以下、図面に基づきこの発明による用紙識別センサの好適な実施の形態を説明する。
図1はこの発明の実施形態における反射型の用紙種類識別センサを説明するための図である。図において、本実施形態ではセンサの素子構成は1個の発光素子1と2個の受光素子2,3とからなっている。なお図中、4は用紙P上に敷設された遮光板である。
【0018】
発光素子1は、所定の入射角度で用紙Pに光を照射するように配置される。第1の受光素子2は、発光素子1の対向側でこの発光素子1と同一角度位置に配置され、また第2の受光素子3は、発光素子1の対向側で第1の受光素子2のほぼ1/2となる角度位置に配置される。この例では、図示のように発光素子1は記録媒体である用紙Pの表面の法線N上からの設置角度を57°に設定している。また2個の受光素子2,3はそれぞれ、57°の角度位置と30°の角度位置に設定してある。
【0019】
また、後述するように第1の受光素子2は、用紙Pからの正反射成分の多い角度位置に配置される。第2の受光素子3は、用紙Pからの混合反射成分の多い角度位置に配置される。
【0020】
図示のように、発光素子1からある一定の広がりを持った光が照射され、用紙Pによって反射された反射光が2個の受光素子2,3に入り、それぞれ電気的信号に変換されて出力される。
【0021】
図1では受発光素子以外に、遮光板4が図示されているが、これは用紙Pからの反射光の面積を一定範囲に限定するものである。反射率の小さな材質を使用しあるいはそのような加工を施すことで、遮光板4からの反射を実質上無視することができるレベル以下としている。したがって、遮光板4の影響は実質的に無くすることができる。図示例においては遮光板4が示されているが、光学的絞りあるいはレンズ構成により、反射面の範囲限定を行うこともできる。
【0022】
図2は、発光素子1の設置位置を法線Nからの設置角度を57°としたときの受光素子2,3の各設置角度に対する出力値の変化と用紙Pの種類による違いを示している。
一般に透明体においては、特別な結晶の場合を除き屈折率は1.5〜1.6程度である。その鏡面反射の特徴は法線から見た角度である入射角θが0〜60°付近までは反射率が小さく、入射角θが70°を越えると反射率が急に上昇することが知られている。
【0023】
さらに、空気中から屈折率nの透明体に入射する場合において、つぎの(1)式を満足する入射角θp のとき、
tanθp =1/n (1)
入射光のうち入射面に平行な偏向成分は全く反射しないので、鏡面反射光は垂直振動成分だけの直線偏向となる。θp は偏向角と言われ、屈折率n=1.5において約57°となる。したがって、この実施形態においては発光素子1の法線Nから見た設置位置角度が57°に設定される。
【0024】
図2において特徴的なことは、普通紙と各種光沢紙の出力に大きな差が見られない受光素子の設置角度30°を基準として見ると、光沢紙サンプルNo.1〜No.5およびOHPシートは設置角度が増加するに従って出力が増加する。普通紙においては設置角度が増加するのに従って出力が減少していることが分る。この結果に着目すると、本発明によれば、従来例において必須であった識別のための判定基準値設定を用いずに用紙種類の識別が可能となる。
【0025】
本実施形態においては、発光素子1から照射されて用紙Pの表面にて反射された反射光を受光して出力される第1の受光素子2の出力電圧(V1 )と第2の受光素子3の出力電圧(V2 )を相対比較することで、つぎの表1に示すように用紙種類を識別している。相対比較するには第2の受光素子3の出力(V2 )を基準電圧とし、第1の受光素子2の出力電圧(V1 )とともに一般的な比較回路に接続することで容易に行うことができる。
【0026】
【表1】

Figure 0004362745
【0027】
本実施形態においては、発光素子1の設置角度位置を図1において57°としたが、この角度に限定した場合にのみ効果が得られるものではない。すなわち基本的には法線Nから45°以上に発光素子1を設置し、第1の受光素子2を発光素子1と対向する側に該発光素子1と同一の角度位置に設置し、第2の受光素子3を第1の受光素子2の設置角度のほぼ1/2の角度(発光素子1の設置角度が45°の場合、22.5°近傍)に設置することで同様な効果が得られる。
【0028】
理論的には発光素子1の設置角度は、より広い範囲で設定することができる。実際には使用する受発光素子1,2,3の形状および記録紙識別センサとしての取付容易性等を考慮すると、前述した法線N上から45°から60°近傍の範囲にあることが望ましい。発光素子1の設置位置を45°よりも小さくすると2つの受光素子2,3の出力差を十分に得られなくなることがある。一方、発光素子1の設置角度を60°以上にすると、そのままでは識別センサとしての形状が大きくなってしまう。
【0029】
さらに、光が用紙Pの表面とほとんど平行になるすれすれの角度で入射する場合(grazing incidence)には、反射率の低い物体や粗面であっても正反射光が増加することが知られている。正確な用紙種類の識別の妨げとなる要素が発生し得るかかる入射角度までの範囲での実施は避けるべきである。このことからも発光素子1の設定角度の上限は60°近傍に設定することが望ましい。
【0030】
本実施形態において、前述のように第2の受光素子3の設置角度を第1の受光素子2の設置角度の約半分の角度とする。これは、一般的な発光素子(LED)においては、内部のチップ表面積が約0.06mm2 (0.25mm角)から約0.16mm2 (0.4mm角)程度の範囲にあり、完全な点光源ではないためである。さらに、発光素子1の表面は特定のレンズ形状を構成していることから、光源からある一定の広がりを以て用紙Pに光が照射され、反射光のこの角度(第2の受光素子3の設置角度)近傍に混合反射の光量の最大値が出現するためである。
【0031】
なお、ここに混合反射(mixed reflection)とは、正反射と拡散反射とが同時に起こる反射を意味し、塗装面、紙面のような拡散物体の反射光は混合反射で、入射角により正反射と拡散反射の比率は変化する。
【0032】
このことは発光素子の内部の光源(実際はGaAsの化合物半導体のチップ)を0.4mm角のサイズと仮定して、光源の光軸上から放射された光束と光源の最外縁部から放射された光束各101本に対する光線追跡法によるシミュレーションを以下の条件にて実施した結果からも確認された。
【0033】
〔条件〕
発光素子と受光素子は一対として、
・発光素子と受光素子の各設置角度:60°
・光源の広がり角:60°
・光線数:光源の光軸上、光源の最外縁部からの放射各101本
・点光源設置位置:光軸上および光軸から0.2mmの位置の2点
・散乱の仮定:ランバーシアン分布による散乱と仮定
(散乱分率=0.5に設定)
【0034】
つぎに、この発明の第2の実施形態について説明する。
第2の実施形態においては、普通紙、光沢紙、OHPシートの3種類の識別を行うようにしている。この場合には、OHPシートと光沢紙を含めた特殊用紙と普通紙の識別を第1の実施形態に従って行った後、光沢紙とOHPシートの識別に比較基準値を設けることで3種類の識別を行うことができる。
【0035】
従来の手段においては識別が困難であった普通紙と光沢紙の識別を第1の実施形態の方法で行ったうえで、OHPシートと光沢紙の識別に必要な比較基準値を設けることは、OHPシートと光沢紙の反射率の違いが大きいことから、容易に確実な識別が可能となる。
【0036】
上記実施形態において、具体的な数値例をあげて本発明を説明したが、この発明はそのような数値にのみ限定されるものではなく、この発明の範囲内で適宜変更等が可能である。
【0037】
【発明の効果】
以上説明したように本発明によれば、この種の用紙識別センサにおいて簡素な構成にして、つねに安定して正確な識別を行うことができ、低コストで優れたセンサを提供することができる等の利点を有している。
【図面の簡単な説明】
【図1】この発明の実施形態における反射型の用紙識別センサを説明するための図である。
【図2】この発明の実施形態における発光素子の設置位置と出力値の関係を示す図である。
【符号の説明】
1 発光素子
2 第1の受光素子
3 第2の受光素子
4 遮光板
P 用紙
N 法線[0001]
BACKGROUND OF THE INVENTION
This invention distinguishes between special paper such as OHP sheets and glossy paper and plain paper according to the difference in the optical reflection characteristics of various paper in the storage state or feeding state in a printing apparatus such as a printer or an electrophotographic copying machine. The present invention relates to a paper identification sensor.
[0002]
[Prior art]
In printing apparatuses such as printers and electrophotographic copying machines, papers other than plain paper such as OHP sheets and glossy papers are provided in response to diversification of purposes of use of printed materials. Since these sheets differ in processing such as surface treatment, it is necessary to switch between printing conditions and sheet conveyance conditions suitable for each.
[0003]
For this reason, various techniques for discriminating the type of paper set in a printing apparatus or the like have been developed. Most of these techniques use optical sensors. For example, in Japanese Patent Laid-Open Nos. 2-56375, 6-56313, 10-198174, and 10-198093, etc. What has been described is known. In either technique, the paper type identification device is a combination of one or two light emitting elements and light receiving elements.
[0004]
In the conventional method for identifying the type of paper in the conventional apparatus, in the process in which the light emitted from the light emitting element is reflected on the paper surface and received by the light receiving element, the reflected light reflected on the paper surface is converted into regular reflection light and irregular reflection light. And divided into Then, the comparison is performed by comparing the value obtained as the specularly reflected light with a preset reference value or by comparing the respective values obtained as the specularly reflected light and the irregularly reflected light with respective preset reference values.
[0005]
By the way, in the conventional paper identification sensor, the main identification target is the identification between the OHP sheet and the plain paper. Since both materials are different, there is also a very large difference in the reflectance of the surface, so that they can be identified relatively easily.
[0006]
[Problems to be solved by the invention]
However, in the conventional paper type identification sensor, the light emitted from the light emitting element is reflected by the paper surface, and the reflected light is received by the light receiving element. Identification is performed by comparing the output value of the light receiving element, which changes depending on the intensity of the reflected light, with a preset reference value.
[0007]
For this reason, the amount of change in the output value (dynamic range) that must be obtained inevitably becomes small, the optical variation of the lens portions of the light emitting element and the light receiving element that are actually used, and the sensitivity as an optical semiconductor. In addition, there is a variation in assembly when the element is assembled as a paper type identification sensor. Considering these, it is extremely difficult to appropriately secure the amount of change in the output value associated with the change in the received light intensity of the reflected light obtained by the light receiving element. Comparing this output value with a reference value that is an absolute value results in insufficient noise margin.
[0008]
For this reason, when manufacturing a paper identification sensor, it is necessary to perform selection in order to suppress variations in the performance of elements to be used, which is a cause of deterioration in productivity and cost increase. Furthermore, with the widespread use of color in printers, electrophotographic copying machines, and other printing devices, glossy paper has come to be used for the purpose of obtaining high-quality printing in addition to OHP sheets along with the demand for color printing of digital images. Yes. The difference in reflectance between glossy paper and plain paper is not as great as the difference between the OHP sheet and plain paper, and the amount of change in output value due to the difference in reflected light intensity obtained by the light receiving element becomes smaller. With the means for comparing the output value of the light receiving element and the set value in the prior art, it is substantially difficult to accurately identify the paper type.
[0009]
Moreover, all the light emitting elements generally diminish their output as the usage time elapses. There is a possibility that identification of various types of paper may not be performed correctly only by receiving reflected light from the paper of the light emitted by the light emitting element with the light receiving element and comparing and determining the absolute value of the output value as in the prior art.
[0010]
The present invention has been made to solve such problems, and provides a sheet identification sensor capable of identifying a sheet type stably at low cost and accurately.
[0011]
[Means for Solving the Problems]
The present invention relates to a sheet identification sensor that identifies the type of sheet based on the reflection characteristics of light applied to the sheet to be identified, and is 45 ° to 60 ° with respect to the normal of the sheet to be identified. A light emitting element that irradiates light with a spread, and an angular position that has a lot of specular reflection components and is arranged at the same angular position as the light emitting element on the opposite side of the light emitting element. And a second light receiving element disposed at an angular position with a large amount of mixed reflection components and at an angle position approximately ½ of the first light receiving element on the opposite side of the light emitting element. , irradiated with light from the light emitting element, and an output voltage V 2 of the first output voltage V 1 and the second light receiving element of the light receiving element by magnitude comparison, if V 1 -V 2 <0 identified as plain paper, and glossy paper or OHP sheet, if V 1 -V 2> 0 Characterized in that it further.
[0012]
In the above configuration, it is preferable that a light shielding plate is disposed on the sheet to be identified, and the area of the reflected light from the sheet is limited to a certain range.
[0015]
According to the present invention, the light emitting element for irradiating the paper whose type is to be identified and the two light receiving elements for receiving the reflected light from the paper are provided. Then, the arrangement angle of the light emitting element with respect to the normal line is set to 45 ° or more, the first light receiving element is arranged at the same angle on the side facing the light emitting element where the specular reflection component from the paper is large, and the second light receiving element The element is arranged in the vicinity of an angle that is half of the arrangement angle of the first light receiving element that has a large mixed reflection component.
[0016]
In the above configuration, when the output value (V 1 ) of the first light receiving element and the output value (V 2 ) of the second light receiving element are measured for various papers, V 1 <V 2 for plain paper. On the other hand, in the case of an OHP sheet or glossy special paper, V 1 > V 2 . Therefore, by comparing the magnitudes of V 1 and V 2 , the paper type can be accurately determined without being affected by variations in the light emission intensity of the light emitting element, variations in the sensitivity of the light receiving element, and assembly variations when assembled as a paper type identification sensor. Can be determined.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a paper identification sensor according to the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining a reflection type paper type identification sensor according to an embodiment of the present invention. In the figure, in this embodiment, the element configuration of the sensor is composed of one light emitting element 1 and two light receiving elements 2 and 3. In the figure, reference numeral 4 denotes a light shielding plate laid on the paper P.
[0018]
The light emitting element 1 is arranged to irradiate the paper P with light at a predetermined incident angle. The first light receiving element 2 is disposed at the same angular position as the light emitting element 1 on the opposite side of the light emitting element 1, and the second light receiving element 3 is disposed on the opposite side of the light emitting element 1 with respect to the first light receiving element 2. It is arranged at an angular position that is approximately ½. In this example, as shown in the drawing, the light emitting element 1 has an installation angle of 57 ° from the normal line N of the surface of the paper P as a recording medium. The two light receiving elements 2 and 3 are set at an angular position of 57 ° and an angular position of 30 °, respectively.
[0019]
Further, as will be described later, the first light receiving element 2 is arranged at an angular position where there are many specular reflection components from the paper P. The second light receiving element 3 is disposed at an angular position where the mixed reflection component from the paper P is large.
[0020]
As shown in the figure, light having a certain spread is emitted from the light emitting element 1, and the reflected light reflected by the paper P enters the two light receiving elements 2 and 3, and is converted into an electrical signal and output. Is done.
[0021]
In FIG. 1, in addition to the light emitting / receiving element, a light shielding plate 4 is shown, but this limits the area of the reflected light from the paper P to a certain range. By using a material having a low reflectance or applying such processing, the reflection from the light shielding plate 4 is set to a level that can be substantially ignored. Therefore, the influence of the light shielding plate 4 can be substantially eliminated. Although the light shielding plate 4 is shown in the illustrated example, the range of the reflecting surface can be limited by an optical aperture or a lens configuration.
[0022]
FIG. 2 shows a change in output value with respect to each installation angle of the light receiving elements 2 and 3 and a difference depending on the type of the paper P when the installation position of the light emitting element 1 is set to 57 ° from the normal line N. .
In general, a transparent body has a refractive index of about 1.5 to 1.6 except for special crystals. The characteristic of the specular reflection is that the reflectance is small until the incident angle θ, which is an angle seen from the normal line, is near 0 to 60 °, and the reflectance rapidly increases when the incident angle θ exceeds 70 °. ing.
[0023]
Furthermore, in the case of entering a transparent body having a refractive index n from the air, when the incident angle θ p satisfies the following equation (1):
tan θ p = 1 / n (1)
Since the deflection component parallel to the incident surface of the incident light is not reflected at all, the specular reflection light is linearly deflected with only the vertical vibration component. θ p is called a deflection angle, and is about 57 ° at a refractive index n = 1.5. Therefore, in this embodiment, the installation position angle viewed from the normal line N of the light emitting element 1 is set to 57 °.
[0024]
In FIG. 2, what is characteristic is that the glossy paper sample No. 2 is observed when the installation angle of the light receiving element of 30 ° where no significant difference is seen in the output of plain paper and various glossy papers. 1-No. The output of the 5 and OHP sheets increases as the installation angle increases. It can be seen that the output of plain paper decreases as the installation angle increases. Focusing on this result, according to the present invention, it is possible to identify the sheet type without using the determination reference value setting that is essential in the conventional example.
[0025]
In the present embodiment, the output voltage (V 1 ) of the first light receiving element 2 output by receiving the reflected light that is irradiated from the light emitting element 1 and reflected by the surface of the paper P, and the second light receiving element. By comparing the output voltage (V 2 ) of No. 3 with respect to each other, the paper type is identified as shown in Table 1 below. The relative comparison can be easily performed by using the output (V 2 ) of the second light receiving element 3 as a reference voltage and connecting it to the general comparison circuit together with the output voltage (V 1 ) of the first light receiving element 2. Can do.
[0026]
[Table 1]
Figure 0004362745
[0027]
In the present embodiment, the installation angle position of the light emitting element 1 is 57 ° in FIG. 1, but the effect is not obtained only when the angle is limited to this angle. That is, basically, the light emitting element 1 is installed at 45 ° or more from the normal line N, the first light receiving element 2 is installed on the side facing the light emitting element 1 at the same angular position as the light emitting element 1, and the second The same effect can be obtained by installing the light receiving element 3 at an angle that is approximately half of the installation angle of the first light receiving element 2 (when the installation angle of the light emitting element 1 is 45 °, it is approximately 22.5 °). It is done.
[0028]
Theoretically, the installation angle of the light emitting element 1 can be set in a wider range. Actually, in consideration of the shape of the light emitting / receiving elements 1, 2, 3 to be used and the ease of mounting as a recording paper identification sensor, it is desirable to be in the range of 45 ° to 60 ° from the normal N described above. . If the installation position of the light emitting element 1 is smaller than 45 °, the output difference between the two light receiving elements 2 and 3 may not be sufficiently obtained. On the other hand, if the installation angle of the light emitting element 1 is set to 60 ° or more, the shape as the identification sensor is increased as it is.
[0029]
Further, it is known that when light is incident at a grazing angle that is almost parallel to the surface of the paper P (grazing incidence), specularly reflected light increases even with low reflectance objects or rough surfaces. Yes. Implementation in the range up to such an incident angle where an element that hinders accurate paper type identification may occur should be avoided. Also from this, it is desirable to set the upper limit of the setting angle of the light emitting element 1 in the vicinity of 60 °.
[0030]
In the present embodiment, as described above, the installation angle of the second light receiving element 3 is set to about half of the installation angle of the first light receiving element 2. This is because in a general light emitting device (LED), the internal chip surface area is in the range of about 0.06 mm 2 (0.25 mm square) to about 0.16 mm 2 (0.4 mm square). This is because it is not a point light source. Further, since the surface of the light emitting element 1 forms a specific lens shape, the light is irradiated onto the paper P with a certain spread from the light source, and this angle of reflected light (the installation angle of the second light receiving element 3). This is because the maximum value of the mixed reflection light quantity appears in the vicinity.
[0031]
Here, mixed reflection means reflection in which specular reflection and diffuse reflection occur simultaneously, and the reflected light of a diffused object such as a painted surface or a paper surface is mixed reflection, and the regular reflection depends on the incident angle. The ratio of diffuse reflection varies.
[0032]
This is based on the assumption that the light source (actually a GaAs compound semiconductor chip) inside the light emitting element is 0.4 mm square size, and the light flux emitted from the optical axis of the light source and the outermost edge of the light source. It was also confirmed from the result of the simulation by the ray tracing method for each of 101 beams under the following conditions.
[0033]
〔conditions〕
As a pair of light emitting element and light receiving element,
・ Each installation angle of light emitting element and light receiving element: 60 °
-Light source spread angle: 60 °
-Number of rays: 101 each on the optical axis of the light source and radiation from the outermost edge of the light source-Point light source installation position: two points on the optical axis and 0.2 mm from the optical axis-Assumption of scattering: Lambertian distribution Assuming scattering by (scattering fraction = 0.5)
[0034]
Next, a second embodiment of the present invention will be described.
In the second embodiment, three types of identification are performed: plain paper, glossy paper, and OHP sheet. In this case, after identifying the special paper and the plain paper including the OHP sheet and the glossy paper according to the first embodiment, a comparison reference value is provided for the identification of the glossy paper and the OHP sheet, thereby identifying three types of discrimination. It can be performed.
[0035]
The identification of plain paper and glossy paper, which is difficult to identify with conventional means, is performed by the method of the first embodiment, and then a comparison reference value necessary for discrimination between the OHP sheet and glossy paper is provided. Since the difference in reflectance between the OHP sheet and the glossy paper is large, reliable identification can be easily performed.
[0036]
In the above embodiment, the present invention has been described with specific numerical examples. However, the present invention is not limited to such numerical values, and can be appropriately changed within the scope of the present invention.
[0037]
【The invention's effect】
As described above, according to the present invention, this type of sheet identification sensor has a simple configuration, can always perform stable and accurate identification, and can provide an excellent sensor at low cost. Has the advantage of
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a reflection type paper identification sensor according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a relationship between an installation position of a light emitting element and an output value in the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light emitting element 2 1st light receiving element 3 2nd light receiving element 4 Light-shielding plate P Paper N Normal line

Claims (2)

識別すべき用紙に照射された光の反射特性に基づき、用紙の種類を識別するようにした用紙識別センサであって、
識別すべき用紙の法線に対して45°〜60°の角度位置に配置され、広がりを以って光を照射する発光素子と、
正反射成分の多い角度位置であって上記発光素子の対向側で該発光素子と同一角度位置に配置された第1の受光素子と、
混合反射成分の多い角度位置であって上記発光素子の対向側で上記第1の受光素子のほぼ1/2となる角度位置に配置された第2の受光素子と、
を備え、
上記発光素子から光を照射し、上記第1の受光素子の出力電圧Vと上記第2の受光素子の出力電圧Vとを大小比較して、V−V<0であれば普通紙と識別し、V−V>0であれば光沢紙またはOHPシートと識別することを特徴とする、用紙識別センサ。
A paper identification sensor that identifies the type of paper based on the reflection characteristics of light applied to the paper to be identified,
A light emitting element that is disposed at an angular position of 45 ° to 60 ° with respect to the normal of the paper to be identified, and that emits light with a spread;
A first light receiving element disposed at the same angular position as the light emitting element on the opposite side of the light emitting element at an angular position with a lot of specular reflection components;
A second light receiving element that is disposed at an angular position with a large amount of mixed reflection components and at an angular position that is approximately ½ of the first light receiving element on the opposite side of the light emitting element;
With
Irradiating light from the light emitting element, by comparing the magnitude of the output voltage V 2 of the first output voltage V 1 and the second light receiving element of the light receiving element, usually if V 1 -V 2 <0 A paper identification sensor, characterized by being identified as paper, and identified as glossy paper or an OHP sheet if V 1 −V 2 > 0.
識別すべき用紙の上に遮光板が配置され、用紙からの反射光の面積を一定範囲に限定することを特徴とする、請求項1に記載の用紙識別センサ。2. The paper identification sensor according to claim 1, wherein a light shielding plate is disposed on the paper to be identified, and the area of the reflected light from the paper is limited to a certain range.
JP37128599A 1999-12-27 1999-12-27 Paper identification sensor Expired - Lifetime JP4362745B2 (en)

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KR100403591B1 (en) * 2001-08-13 2003-10-30 삼성전자주식회사 Discrimanating method of print media
JP3734247B2 (en) 2002-01-22 2006-01-11 キヤノン株式会社 Discrimination device for type of recording medium, discriminating method, and recording device
JP2003327346A (en) 2002-05-14 2003-11-19 Sharp Corp Optical object distinguishing device and printing device using it
JP4002874B2 (en) 2003-09-08 2007-11-07 シャープ株式会社 Optical object identification device and printing device
US7676169B2 (en) * 2006-05-22 2010-03-09 Lexmark International, Inc. Multipath toner patch sensor for use in an image forming device
JP6236804B2 (en) * 2013-03-05 2017-11-29 セイコーエプソン株式会社 Imaging apparatus and brightness adjustment method

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