JP7297024B2 - image forming device - Google Patents

image forming device Download PDF

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JP7297024B2
JP7297024B2 JP2021163721A JP2021163721A JP7297024B2 JP 7297024 B2 JP7297024 B2 JP 7297024B2 JP 2021163721 A JP2021163721 A JP 2021163721A JP 2021163721 A JP2021163721 A JP 2021163721A JP 7297024 B2 JP7297024 B2 JP 7297024B2
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light
recording material
image forming
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image
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JP2022008843A5 (en
JP2022008843A (en
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瑞樹 石本
伯夫 松井
昌文 門出
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Canon Inc
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Description

本発明は、記録材に含まれる水分量に関する値を検知する画像形成装置に関する。 The present invention relates to an image forming apparatus that detects a value related to the amount of water contained in a recording material.

特許文献１及び２は、被測定物に含まれる水分量を検知する構成を開示している。特許文献１では、水の吸収波長（１４５０ｎｍ）の光と、水の非吸収波長（１３００ｎｍ）の光とを用いて記録材の内部散乱光を検知することで水分量を検知している。また、特許文献２では、水の吸収波長の光と、水の非吸収波長の光とを被測定物に照射し、被測定物からの透過光又は反射光を検知することで水分量を検知している。 Patent Literatures 1 and 2 disclose configurations for detecting the amount of water contained in an object to be measured. In Japanese Patent Application Laid-Open No. 2002-103000, the water content is detected by detecting the internally scattered light of the recording material using light with a water absorption wavelength (1450 nm) and water non-absorption wavelength light (1300 nm). Further, in Patent Document 2, the water content is detected by irradiating an object to be measured with light of a water-absorbing wavelength and light of a non-water-absorbing wavelength, and detecting transmitted light or reflected light from the measured object. are doing.

特開２０１３－５７５１３号公報JP 2013-57513 A 特開平８－８２５９８号公報JP-A-8-82598

しかしながら、特許文献１及び２の構成では、水の吸収波長である１４５０ｎｍや１９４０ｎｍの光を射出する光源と、これら波長において必要な受光感度が得られる受光素子を必要とする。具体的には、ＩｎＧａＡｓ（Ｉｎｄｉｕｍ Ｇａｌｌｉｕｍ Ａｒｓｅｎｉｄｅ）を材料としたＬＥＤやフォトダイオード等の高価な光学素子が必要となりコスト高となる。 However, the configurations of Patent Documents 1 and 2 require a light source that emits light of 1450 nm and 1940 nm, which are water absorption wavelengths, and a light receiving element capable of obtaining the required light sensitivity at these wavelengths. Specifically, expensive optical elements such as LEDs and photodiodes made of InGaAs (Indium Gallium Arsenide) are required, resulting in high costs.

本発明は、高価な光学素子を使用することなく記録材の水分量に関する値を検知できる画像形成装置を提供するものである。 SUMMARY OF THE INVENTION The present invention provides an image forming apparatus capable of detecting a value relating to the moisture content of a recording material without using an expensive optical element.

本発明の一態様によると、画像形成装置は、記録材に画像を形成する画像形成手段と、４００ｎｍから８００ｎｍまでの範囲に含まれるピーク波長をもつ第一の光を記録材に照射する第一の光源と、前記第一の光のピーク波長よりも長く、８００ｎｍから１０００ｎｍまでの範囲に含まれるピーク波長をもつ第二の光を前記記録材に照射する第二の光源と、４００ｎｍから１０００ｎｍの範囲に受光感度を有し、前記記録材を透過した前記第一の光と前記第二の光を受光する受光手段と、前記記録材の坪量に関する情報を取得する取得手段と、前記受光手段が受光した前記第一の光および前記第二の光と、前記取得手段により取得された前記記録材の坪量に関する情報と、に基づいて、前記画像形成手段が前記記録材に画像を形成する画像形成条件を制御する制御手段と、を有することを特徴とする。

According to one aspect of the present invention, an image forming apparatus includes an image forming means for forming an image on a recording material, and a first light having a peak wavelength within a range from 400 nm to 800 nm for irradiating the recording material. a light source for irradiating the recording material with a second light having a peak wavelength longer than the peak wavelength of the first light and within a range from 800 nm to 1000 nm; light receiving means having light sensitivity in a range and receiving the first light and the second light transmitted through the recording material; obtaining means for obtaining information on basis weight of the recording material; and light receiving means The image forming means forms an image on the recording material based on the first light and the second light received by and the information on the basis weight of the recording material obtained by the obtaining means. and control means for controlling image forming conditions.

本発明によると、高価な光学素子を使用することなく記録材の水分量に関する値を検知することができる。 According to the present invention, it is possible to detect the water content of the recording material without using an expensive optical element.

一実施形態による画像形成装置の構成図。1 is a configuration diagram of an image forming apparatus according to an embodiment; FIG. 一実施形態による水分検知装置の構成図。The block diagram of the water|moisture content detection apparatus by one Embodiment. 一実施形態による水分検知原理の説明図。Explanatory drawing of the water|moisture content detection principle by one Embodiment. 一実施形態による水分判定情報の説明図。Explanatory drawing of moisture determination information by one Embodiment. 一実施形態による記録材の水分検知処理のフローチャート。4 is a flow chart of moisture detection processing for a recording material according to an embodiment; 一実施形態による水分判定情報の説明図。Explanatory drawing of moisture determination information by one Embodiment. 一実施形態による坪量判定情報の説明図。FIG. 4 is an explanatory diagram of basis weight determination information according to one embodiment;

以下、本発明の例示的な実施形態について図面を参照して説明する。なお、以下の実施形態は例示であり、本発明を実施形態の内容に限定するものではない。また、以下の各図においては、実施形態の説明に必要ではない構成要素については図から省略する。 Exemplary embodiments of the invention will now be described with reference to the drawings. In addition, the following embodiments are examples, and the present invention is not limited to the contents of the embodiments. Also, in the following drawings, constituent elements that are not necessary for the description of the embodiments are omitted from the drawings.

＜第一実施形態＞
図１は、本実施形態による水分検知装置を含む画像形成装置１の概略的な構成図である。画像形成装置１は、イエロー（Ｙ）、マゼンタ（Ｍ）、シアン（Ｃ）、ブラック（Ｋ）の４色のトナー（現像材）それぞれで形成したトナー像を重ね合わせることでカラー画像を形成する。図１において、参照符号の末尾のＹ、Ｍ、Ｃ及びＫは、対応する部材が形成に係るトナーの色がそれぞれ、イエロー、マゼンタ、シアン、ブラックであることを示している。なお、以下の説明においてトナーの色を区別する必要がない場合には、参照符号の末尾のアルファベットの除いた参照符号を使用する。 <First embodiment>
FIG. 1 is a schematic configuration diagram of an image forming apparatus 1 including a moisture detection device according to this embodiment. The image forming apparatus 1 forms a color image by superimposing toner images respectively formed with four color toners (developers) of yellow (Y), magenta (M), cyan (C), and black (K). . In FIG. 1, Y, M, C, and K at the end of the reference numerals indicate that the colors of the toners formed by the corresponding members are yellow, magenta, cyan, and black, respectively. In the following description, when there is no need to distinguish between toner colors, the reference numerals without the alphabet at the end of the reference numerals are used.

感光体１１は、像担持体であり、画像形成時、図中の矢印の方向に回転駆動される。帯電ローラ１２は、感光体１１の表面を一様な電位に帯電させる。走査部１３は、帯電された感光体１１を光で走査・露光して感光体１１に静電潜像を形成する。現像部１４は対応する色のトナーを有し、現像ローラ１５が出力する現像バイアスによりトナーを感光体１１の静電潜像に付着させ、これによりトナー像を感光体１１に形成する。一次転写ローラ１６は、一次転写バイアスを出力して感光体１１のトナー像を中間転写ベルト１７に転写する。中間転写ベルト１７は、画像形成時、駆動ローラ１８の回転に従属して回転駆動される。各感光体１１に形成されたトナー像を、回転駆動される中間転写ベルト１７に重ねて転写することで多色のトナー像を形成することができる。また、中間転写ベルト１７に転写されたトナー像は、中間転写ベルト１７の回転により二次転写ローラ１９の対向位置へと搬送される。 The photoreceptor 11 is an image carrier, and is rotationally driven in the direction of the arrow in the drawing during image formation. The charging roller 12 charges the surface of the photoreceptor 11 to a uniform potential. The scanning unit 13 scans and exposes the charged photoreceptor 11 with light to form an electrostatic latent image on the photoreceptor 11 . The developing unit 14 has toner of a corresponding color, and adheres the toner to the electrostatic latent image on the photoreceptor 11 by means of a developing bias output by the developing roller 15 , thereby forming a toner image on the photoreceptor 11 . A primary transfer roller 16 outputs a primary transfer bias to transfer the toner image on the photosensitive member 11 to the intermediate transfer belt 17 . The intermediate transfer belt 17 is rotationally driven following the rotation of the drive roller 18 during image formation. A multi-color toner image can be formed by superimposing and transferring the toner images formed on the photoreceptors 11 onto the intermediate transfer belt 17 that is driven to rotate. Further, the toner image transferred to the intermediate transfer belt 17 is conveyed to a position facing the secondary transfer roller 19 as the intermediate transfer belt 17 rotates.

また、給紙カセット２の記録材Ｐは、給紙ローラ４により搬送路に給紙され、搬送ローラ対５及びレジストレーションローラ対６により二次転写ローラ１９の対向位置へと搬送される。二次転写ローラ１９は、二次転写バイアスを出力して、中間転写ベルト１７のトナー像を記録材Ｐに転写する。トナー像が転写された記録材Ｐは、定着部２０に搬送される。定着部２０は、記録材Ｐを加熱・加圧してトナー像を記録材Ｐに定着させる。トナー像が定着された記録材Ｐは、排紙ローラ２１により画像形成装置１の外部に排出される。図１において、参照符号４０で示される点線内の部材は、記録材Ｐに画像を形成する画像形成部を構成している。 Also, the recording material P in the paper feed cassette 2 is fed to the conveying path by the paper feed roller 4 and conveyed to the position facing the secondary transfer roller 19 by the pair of conveying rollers 5 and the pair of registration rollers 6 . The secondary transfer roller 19 outputs a secondary transfer bias to transfer the toner image on the intermediate transfer belt 17 onto the recording material P. FIG. The recording material P onto which the toner image has been transferred is conveyed to the fixing section 20 . The fixing unit 20 heats and presses the recording material P to fix the toner image on the recording material P. As shown in FIG. The recording material P on which the toner image has been fixed is discharged to the outside of the image forming apparatus 1 by a discharge roller 21 . In FIG. 1, the member within the dotted line indicated by reference numeral 40 constitutes an image forming section that forms an image on the recording material P. As shown in FIG.

レジストレーションローラ対６より記録材の搬送方向の下流側には、記録材Ｐを検知するレジストレーションセンサ３が設けられている。また、搬送方向において、レジストレーションセンサ３の下流側、かつ、二次転写ローラ１９の上流側には、記録材判別装置３０が設けられている。記録材判別装置３０は、送信部３３と、受信部３４とを有し、記録材Ｐの坪量を検知する坪量検知部３１と、記録材Ｐの表面性を検知する表面性検知部３２と、を備えている。さらに、搬送方向において、記録材判別装置３０の下流側、かつ、二次転写ローラ１９の上流側には、水分検知装置３５が設けられている。水分検知装置３５は、発光部３７及び受光部３８を有する水分検知センサ部３６と、水分検知制御部３９と、を備えている。 A registration sensor 3 for detecting the recording material P is provided downstream of the registration roller pair 6 in the conveying direction of the recording material. A recording material discriminating device 30 is provided downstream of the registration sensor 3 and upstream of the secondary transfer roller 19 in the conveying direction. The recording material discrimination device 30 has a transmission unit 33 and a reception unit 34, and includes a basis weight detection unit 31 for detecting the basis weight of the recording material P and a surface property detection unit 32 for detecting the surface property of the recording material P. and have. Further, a moisture detection device 35 is provided downstream of the recording material discrimination device 30 and upstream of the secondary transfer roller 19 in the conveying direction. The moisture detection device 35 includes a moisture detection sensor section 36 having a light emitting section 37 and a light receiving section 38 and a moisture detection control section 39 .

画像形成装置１の制御部１０は、画像形成装置１全体の制御を行い、１つ以上のプロセッサと、プロセッサが使用するプログラムやデータを格納する不揮発性メモリと、プロセッサの作業領域として使用されるＲＡＭ等を備えている。制御部１０は、例えば、記録材判別装置３０により検知した記録材Ｐの種類に応じた印刷モードを決定して画像形成装置１の動作を一括して制御する。 A control unit 10 of the image forming apparatus 1 controls the entire image forming apparatus 1, and includes one or more processors, a nonvolatile memory for storing programs and data used by the processors, and a work area for the processors. A RAM and the like are provided. For example, the control unit 10 determines a print mode according to the type of the recording material P detected by the recording material determination device 30 and collectively controls the operations of the image forming apparatus 1 .

続いて、水分検知装置３５について説明する。図２（Ａ）は、水分検知装置３５のブロック図である。水分検知センサ部３６は、記録材Ｐの搬送路に対して互いに逆側に設けられる発光部３７及び受光部３８を有し、発光部３７から射出される光を受光部３８で受光する。ここで、水分検知センサ部３６の主要部である発光部３７及び受光部３８の構成の詳細を図２（Ｂ）に示す。 Next, the moisture detection device 35 will be described. FIG. 2A is a block diagram of the moisture detector 35. As shown in FIG. The moisture detection sensor portion 36 has a light emitting portion 37 and a light receiving portion 38 provided on opposite sides of the conveying path of the recording material P, and the light emitted from the light emitting portion 37 is received by the light receiving portion 38 . Here, FIG. 2B shows details of the configuration of the light-emitting portion 37 and the light-receiving portion 38, which are main portions of the moisture detection sensor portion 36. As shown in FIG.

発光部３７は、発光素子３７ａ及び発光素子３７ｂと、それらを駆動させるための駆動回路（不図示）から構成される。本実施形態において、発光素子３７ａは、ピーク波長が５６０ｎｍである光を射出するＬＥＤであり、発光素子３７ｂは、ピーク波長が８５０ｎｍである光を射出するＬＥＤである。約４００～８００ｎｍの波長帯は、一般的に、可視光領域と呼ばれ、約８００～２５００ｎｍの波長帯は、一般的に、近赤外光領域と呼ばれる。よって、以下では、発光素子３７ａが射出する光を「可視光」と表記し、発光素子３７ｂが射出する光を「近赤外光」と表記して区別する。なお、上述した、発光素子３７ａ及び発光素子３７ｂの波長は一例であり、可視光領域の波長及び近赤外光領域の波長であれば良い。 The light emitting unit 37 is composed of a light emitting element 37a and a light emitting element 37b, and a drive circuit (not shown) for driving them. In this embodiment, the light emitting element 37a is an LED that emits light with a peak wavelength of 560 nm, and the light emitting element 37b is an LED that emits light with a peak wavelength of 850 nm. A wavelength band of about 400-800 nm is commonly referred to as the visible light region, and a wavelength band of about 800-2500 nm is commonly referred to as the near-infrared region. Therefore, hereinafter, the light emitted by the light emitting element 37a is referred to as "visible light", and the light emitted by the light emitting element 37b is referred to as "near-infrared light" for distinction. Note that the wavelengths of the light-emitting elements 37a and 37b described above are examples, and wavelengths in the visible light region and near-infrared light region may be used.

発光素子３７ａが射出した可視光は、アパーチャ３７ｃを介して記録材Ｐを照射する。同様に、発光素子３７ｂが射出した近赤外光は、アパーチャ３７ｄを介して記録材Ｐを照射する。アパーチャ３７ｃ及び３７ｄは、記録材Ｐ表面の照射面積を制限し、記録材Ｐを透過した光を受光部３８の所望の範囲で受光させるために設けられている。しかしながら、発光素子３７ａ及び発光素子３７ｂが指向性の高い光を射出する場合、アパーチャ３７ｃ及びアパーチャ３７ｄを設けなくとも良い。 The visible light emitted by the light emitting element 37a irradiates the recording material P through the aperture 37c. Similarly, the near-infrared light emitted by the light emitting element 37b irradiates the recording material P through the aperture 37d. The apertures 37c and 37d are provided to limit the irradiation area of the surface of the recording material P so that the light transmitted through the recording material P is received within a desired range of the light receiving section . However, when the light emitting elements 37a and 37b emit highly directional light, the apertures 37c and 37d may not be provided.

受光部３８は、受光素子３８ａ及び受光素子３８ｂを備えている。受光素子３８ａ及び受光素子３８ｂは、それぞれ、光電変換素子であり、例えば、汎用のＣＭＯＳセンサである。なお、受光素子としては、半導体シリコンを用いたセンサ、例えば、Ｓｉフォトダイオード、Ｓｉフォトトランジスタ、ＣＣＤセンサ、ＮＭＯＳセンサ等を使用することができる。また、受光面の形状が、エリア型やライン型のものも使用することもできる。これらの光電変換素子は、一般に約４００～１０００ｎｍの波長帯に受光感度を有する。つまり、受光素子３８ａ及び受光素子３８ｂは、発光素子３７ａ及び発光素子３７ｂのピーク波長を含む波長帯に受光感度を有する。 The light receiving section 38 includes a light receiving element 38a and a light receiving element 38b. The light receiving element 38a and the light receiving element 38b are photoelectric conversion elements, for example, general-purpose CMOS sensors. A sensor using semiconductor silicon, such as a Si photodiode, a Si phototransistor, a CCD sensor, or an NMOS sensor, can be used as the light receiving element. Also, the shape of the light receiving surface may be of area type or line type. These photoelectric conversion elements generally have photosensitivity in the wavelength band of approximately 400 to 1000 nm. That is, the light receiving elements 38a and 38b have light sensitivity in a wavelength band including the peak wavelengths of the light emitting elements 37a and 37b.

記録材Ｐを透過した可視光及び近赤外光は、それぞれ受光素子３８ａ及び３８ｂにより受光される。なお、本実施形態では、２つの発光素子３７ａ及び３７ｂそれぞれに対応して２つの受光素子３８ａ及び３８ｂを使用している。しかしながら、各発光素子３８ａ、３８ｂが射出し、記録材Ｐを透過した透過光を区別して検出できれば良く、水分検知センサ部３６の構成は図２（Ｂ）の構成に限定されない。例えば、発光素子３７ａと発光素子３７ｂからの透過光が受光素子の異なる範囲を照射し、受光素子が、発光素子３７ａからの透過光と発光素子３７ｂからの透過光それぞれの受光量を示す信号を個別に出力できれば、受光素子を１つとすることもできる。さらに、各発光素子３８ａ、３８ｂの発光タイミングを異ならせるといった制御を行えば、各発光素子３８ａ、３８ｂからの透過光の受光範囲が重複しても、受光量を個別に検出することができる。さらに、発光素子、アパーチャ、受光素子それぞれの距離や、光の射出角度は、記録材Ｐの透過光を受光可能であれば良く、例えば、記録材Ｐおよび受光面に対して光を斜めに射出する構成であっても良い。 The visible light and near-infrared light transmitted through the recording material P are received by the light receiving elements 38a and 38b, respectively. In this embodiment, two light receiving elements 38a and 38b are used corresponding to the two light emitting elements 37a and 37b, respectively. However, the structure of the moisture detection sensor section 36 is not limited to the structure shown in FIG. For example, the transmitted light from the light emitting element 37a and the light emitting element 37b irradiate different ranges of the light receiving element, and the light receiving element generates a signal indicating the received amount of each of the transmitted light from the light emitting element 37a and the transmitted light from the light emitting element 37b. If the signals can be output individually, the number of light receiving elements can be one. Furthermore, by performing control such that the light emission timings of the light emitting elements 38a and 38b are different, even if the light receiving ranges of the transmitted light from the light emitting elements 38a and 38b overlap, the amounts of received light can be detected individually. Furthermore, the distances between the light emitting element, the aperture, and the light receiving element, and the light emission angle may be set as long as the light transmitted through the recording material P can be received. The configuration may be such that

図２（Ａ）に戻り、水分検知制御部３９について説明する。水分検知制御部３９は、発光部３７に対して、発光部３７の発光素子３７ａ及び３７ｂが射出する光のＯＮ／ＯＦＦ制御と、その光量制御（光強度制御）を行う。なおこれらは、制御部１０からの制御信号に基づいて行われる。発光素子３７ａ及び３７ｂの発光光量は、記録材Ｐの透過光が受光素子３８ａ及び３８ｂで受光できる大きさとなる様に制御される。なお、最適な発光光量は、発光素子及び受光素子の特性により異なる。また、ＬＥＤなどの発光素子では、駆動回路の電圧変動の影響で発光光量が時間的に変動する場合があり、これは水分量の検知精度を低下させる原因となる。この場合は、例えば定電流回路などで発光光量を安定させることができる。さらに、水分検知制御部３９は受光部３８に対して、受光タイミングを制御する制御信号を出力する。これにより、受光素子３８ａ及び受光素子３８ｂの受光時間が同等になるように制御される。 Returning to FIG. 2A, the moisture detection control section 39 will be described. The moisture detection control unit 39 performs ON/OFF control of the light emitted from the light emitting elements 37a and 37b of the light emitting unit 37 and controls the amount of light (light intensity control). Note that these are performed based on a control signal from the control unit 10 . The amount of light emitted by the light emitting elements 37a and 37b is controlled so that the light transmitted through the recording material P can be received by the light receiving elements 38a and 38b. It should be noted that the optimum amount of emitted light differs depending on the characteristics of the light emitting element and the light receiving element. In addition, in a light-emitting element such as an LED, the amount of emitted light may fluctuate over time due to voltage fluctuations in the drive circuit, which causes a decrease in the accuracy of moisture content detection. In this case, the amount of emitted light can be stabilized by, for example, a constant current circuit. Furthermore, the moisture detection control section 39 outputs a control signal for controlling the light reception timing to the light receiving section 38 . As a result, the light receiving times of the light receiving elements 38a and 38b are controlled to be equal.

また、水分検知制御部３９は、受光部３８から可視光及び近赤外光の受光光量を示す受光データを取得し、受光データに基づいて記録材Ｐの水分量（含水量）に関する値を算出する。そして、算出した水分量に関する値を示す含水データを制御部１０に出力する。なお、水分検知制御部３９は、特定用途向けの集積回路（ＡＳＩＣ）上で実現することができ、本実施形態では、ＡＳＩＣ上に水分検知制御部３９を実現しているものとする。しかしながら、画像形成装置１の制御部１０のプロセッサにプログラムを実行させることで水分検知制御部３９を実現することもできる。 Further, the moisture detection control unit 39 acquires received light data indicating the amount of received light of visible light and near-infrared light from the light receiving unit 38, and calculates a value related to the amount of moisture (moisture content) of the recording material P based on the received light data. do. Then, water content data indicating the calculated value related to the water content is output to the control unit 10 . The moisture detection controller 39 can be implemented on an application-specific integrated circuit (ASIC), and in this embodiment, the moisture detection controller 39 is implemented on the ASIC. However, the moisture detection control section 39 can be implemented by causing the processor of the control section 10 of the image forming apparatus 1 to execute a program.

画像形成装置１の制御部１０は、水分検知制御部３９への制御信号の出力を行い、水分検知装置３５から取得した含水データにより、画像形成条件を制御する。例えば、制御部１０は、記録材Ｐの水分量に応じて二次転写ローラ１９が出力する転写電圧である二次転写バイアスや、二次転写バイアスにより流れる転写電流を制御する。また、制御部１０は、記録材Ｐの含水率に応じて定着部２０の定着温度をする。具体的には、記録材Ｐの水分量が低いと、記録材Ｐの抵抗が大きくなるため、転写電流が大きくなるよう二次転写バイアスを高くする。また、記録材Ｐの水分量が高いと、定着不良が懸念されるため定着温度を上げる。 The control section 10 of the image forming apparatus 1 outputs a control signal to the moisture detection control section 39 and controls the image forming conditions based on the moisture content data acquired from the moisture detection device 35 . For example, the control unit 10 controls the secondary transfer bias, which is the transfer voltage output by the secondary transfer roller 19 according to the water content of the recording material P, and the transfer current that flows due to the secondary transfer bias. Further, the control unit 10 adjusts the fixing temperature of the fixing unit 20 according to the moisture content of the recording material P. FIG. Specifically, when the water content of the recording material P is low, the resistance of the recording material P increases, so the secondary transfer bias is increased so as to increase the transfer current. Further, if the water content of the recording material P is high, the fixing temperature is raised because there is a concern that the fixing may be defective.

以下、記録材の水分量に関する値である含水率の算出について説明する。まず、発光素子３７ａ及び３７ｂが射出した光を、記録材Ｐを透過させることなく受光素子３８ａ及び３８ｂに受光させたときの受光量を以下では紙無受光量と呼ぶものとする。また、発光素子３７ａ及び３７ｂが射出した光を、記録材Ｐを透過させて受光素子３８ａ及び受光素子３８ｂに受光させたときの受光量を以下では紙有受光量と呼ぶものとする。このとき、発光素子３７ａ及び３７ｂそれぞれが射出した光の記録材Ｐの透過特性、つまり、記録材Ｐを光が透過する度合いを示す検出値は、例えば、以下の式（１）で求めることができる。
検出値＝紙有受光量×係数／紙無受光量 （１）
つまり、記録材Ｐの透過特性を示す検出値は、紙有受光量と紙無受光量の比に係数を乗じたものである。ここで、係数は、発光素子３７ａ及び３７ｂの発光光量差や、受光素子３８ａ及び３８ｂの受光波長に対する受光感度の違い（分光感度特性）を補正し、正規化した紙有受光量を求めるためのものであり、予め求めて水分検知制御部３９に格納しておく。よって、係数及び紙無受光量で正規化した紙有受光量は、発光素子３７ａ及び３７ｂを所定の発光強度で発光させたときに、記録材Ｐを透過する透過光量を示すものということもできる。このため、以下では、検出値を透過光量と呼ぶものとする。なお、例えば、発光素子３７ａ及び３７ｂの発光強度と、受光素子３８ａ及び３８ｂの感度を予め調整すれば、紙有受光量を透過光量とすることもできる。 Calculation of the water content, which is a value related to the water content of the recording material, will be described below. First, the amount of light received by the light receiving elements 38a and 38b when the light emitted by the light emitting elements 37a and 37b is received by the light receiving elements 38a and 38b without being transmitted through the recording material P is hereinafter referred to as the non-paper light amount. Further, the amount of light received when the light emitted by the light emitting elements 37a and 37b is transmitted through the recording material P and received by the light receiving elements 38a and 38b is hereinafter referred to as the light receiving amount with paper. At this time, the transmission characteristics of the recording material P for the light emitted by the light emitting elements 37a and 37b, that is, the detection value indicating the degree of light transmission through the recording material P can be obtained, for example, by the following equation (1). can.
Detected value = amount of received light with paper x coefficient / amount of received light without paper (1)
That is, the detected value indicating the transmission characteristics of the recording material P is obtained by multiplying the ratio of the amount of light received with paper and the amount of light received without paper by a coefficient. Here, the coefficients are used to correct the difference in the amount of light emitted by the light emitting elements 37a and 37b and the difference in light receiving sensitivity (spectral sensitivity characteristics) with respect to the light receiving wavelengths of the light receiving elements 38a and 38b, and to obtain the normalized amount of received light with paper. It is obtained in advance and stored in the moisture detection control section 39 . Therefore, the amount of light received with paper normalized by the coefficient and the amount of light without paper can also be said to indicate the amount of light transmitted through the recording material P when the light emitting elements 37a and 37b are caused to emit light with a predetermined light emission intensity. . Therefore, the detected value is hereinafter referred to as the amount of transmitted light. For example, if the light emission intensity of the light emitting elements 37a and 37b and the sensitivity of the light receiving elements 38a and 38b are adjusted in advance, the amount of light received with paper can be used as the amount of transmitted light.

続いて、記録材Ｐの透過光量と、記録材Ｐの含水量との関係について説明する。図３（Ａ）は、可視光及び近赤外光それぞれについて、水分を含んでいない乾燥時の記録材Ｐの透過光量を示している。光は波長が長くなるに従って記録材Ｐを透過しやすくなるため、近赤外光は可視光より透過光量が大きくなる。 Next, the relationship between the amount of light transmitted through the recording material P and the water content of the recording material P will be described. FIG. 3A shows the amount of light transmitted through the dry recording material P containing no water for each of visible light and near-infrared light. Since the longer the wavelength of light, the easier it is to pass through the recording material P, the amount of transmitted light of near-infrared light is greater than that of visible light.

一方、記録材Ｐが吸湿すると、記録材Ｐに含まれる水分により記録材Ｐの透過特性は変化する。この変化を与える要因の１つに、記録材Ｐ表面での乱反射特性の変化がある。具体的には、記録材Ｐに光を照射した場合、記録材Ｐの主成分である植物繊維の凹凸により記録材Ｐの表面で乱反射が生じる。ここで記録材Ｐに含まれる水分量が変化すると、記録材Ｐ表面の境界条件が変化し、記録材Ｐの表面での乱反射量が変化する。具体的には、記録材Ｐに含まれる水分量が多くなると、記録材Ｐの表面での乱反射量は減少し、よって、記録材Ｐの透過光量は大きくなる。なお、乱反射特性は波長依存性が少ない。よって、記録材Ｐに含まれる水分量の変化による乱反射特性の変化により、可視光及び近赤外光の透過光量は変化するが、その変化量は略同じである。 On the other hand, when the recording material P absorbs moisture, the moisture contained in the recording material P causes the transmission characteristics of the recording material P to change. One of the factors that cause this change is a change in diffused reflection characteristics on the surface of the recording material P. FIG. Specifically, when the recording material P is irradiated with light, diffused reflection occurs on the surface of the recording material P due to unevenness of plant fibers that are the main component of the recording material P. As shown in FIG. Here, when the amount of water contained in the recording material P changes, the boundary conditions on the surface of the recording material P change, and the amount of irregular reflection on the surface of the recording material P changes. Specifically, when the amount of water contained in the recording material P increases, the amount of diffused reflection on the surface of the recording material P decreases, so the amount of light transmitted through the recording material P increases. In addition, the irregular reflection characteristic has little wavelength dependency. Therefore, although the amount of transmitted light of visible light and near-infrared light changes due to the change in irregular reflection characteristics caused by the change in the amount of water contained in the recording material P, the amount of change is substantially the same.

また、記録材Ｐの透過特性に変化を与える要因の１つに、記録材Ｐに含まれる水分による光の吸収がある。水は、光を吸収する特性（吸光特性）を有するが、その吸収の程度は光の波長によって異なる。具体的には、波長が長くなると吸収量は増加する。ここで、記録材Ｐの含水量の増加による、吸光特性に基づく透過光量の減少量は、乱反射特性に基づく透過光量の増加量より小さい。つまり、記録材Ｐの含水量が増加すると、近赤外光及び可視光の透過光量は全体として増加するが、近赤外光の透過光量の増加量は、可視光の透過光量の増加量よりも小さい。この様子を図３（Ｂ）に示す。吸湿時の記録材Ｐの透過光量は、図３（Ａ）に示す乾燥時と比較して増加する。ただし、増加量は、吸光特性の波長依存性により、近赤外光と比較して可視光の方が大きくなる。 One of the factors that cause changes in the transmission characteristics of the recording material P is absorption of light by water contained in the recording material P. FIG. Water has a property of absorbing light (light absorption property), and the degree of absorption varies depending on the wavelength of light. Specifically, the longer the wavelength, the greater the absorption. Here, the amount of decrease in the amount of transmitted light based on the light absorption characteristic due to the increase in the water content of the recording material P is smaller than the amount of increase in the amount of transmitted light based on the irregular reflection characteristic. That is, when the water content of the recording material P increases, the amount of transmitted light of near-infrared light and visible light increases as a whole, but the amount of increase in the amount of transmitted light of near-infrared light is greater than the amount of increase in the amount of transmitted light of visible light. is also small. This state is shown in FIG. The amount of light transmitted through the recording material P when it absorbs moisture increases compared to when it is dry as shown in FIG. 3A. However, the amount of increase is greater for visible light than for near-infrared light due to the wavelength dependence of light absorption characteristics.

本実施形態では、可視光の透過光量と、近赤外光の透過光量との光量差を、記録材Ｐの含水量を評価するための評価値とする。なお、光量差は、以下の式（２）で求められる。
光量差＝近赤外光の透過光量－可視光の透過光量 （２）
上述した様に、記録材Ｐの含水量が変化したときの、乱反射特性に基づく透過光量の変化には波長依存性が殆どないため、光量差の計算において乱反射特性に基づく透過光量の変化は相殺される。一方、記録材Ｐの含水量が変化したときの吸光特性に基づく透過光量の変化には波長依存性があり、よって、光量差は、記録材Ｐの含水量が変化すると変化する。 In the present embodiment, the difference between the transmitted light amount of visible light and the transmitted light amount of near-infrared light is used as an evaluation value for evaluating the water content of the recording material P. FIG. Note that the light amount difference is obtained by the following formula (2).
Light amount difference = Transmitted light amount of near-infrared light - Transmitted light amount of visible light (2)
As described above, when the water content of the recording material P changes, the change in the amount of transmitted light based on the irregular reflection characteristics has almost no wavelength dependency. be done. On the other hand, the change in the amount of transmitted light based on the light absorption characteristic when the water content of the recording material P changes has wavelength dependence.

図４は、記録材Ｐの含水率と光量差との関係を示している。なお、含水率とは、記録材Ｐの坪量に対する記録材Ｐの含水量の比率（％）であり、記録材Ｐの含水量を示す値である。なお、図４は、記録材Ｐとして坪量が６０ｇ／ｍ２の普通紙（６０ｇ紙）を用いた場合の、含水率と光量差との測定結果を示している。図３を用いて説明した様に、記録材Ｐの含水率が増加するに従い光量差は減少している。水分検知制御部３９に、予め、図４の関係を示す式、テーブル等の水分判定情報を保持させておく。そして、水分検知制御部３９は、水分判定情報と、評価値である光量差と、に基づき含水率を判定する。なお、本実施形態では、記録材Ｐの含水量を示す値として、含水率を使用するが、水分判定情報として、光量と含水量との関係を示すものを使用し、含水量を求める形態であっても良い。また、本実施形態では、可視光と近赤外光の透過光量の光量差を評価値としているが、含水量に相関のある値であれば光量差を評価値とする構成に本発明は限定されない。例えば、可視光の透過光量と近赤外光の透過光量との比を評価値としても良い。つまり、評価値として、以下の式（４）で示す光量比を使用する構成であっても良い。
光量比＝近赤外光の透過光量／可視光の透過光量 （４） FIG. 4 shows the relationship between the moisture content of the recording material P and the light amount difference. Note that the moisture content is the ratio (%) of the moisture content of the recording material P to the basis weight of the recording material P, and is a value indicating the moisture content of the recording material P. Note that FIG. 4 shows the measurement results of the moisture content and the light amount difference when plain paper (60 g paper) having a basis weight of 60 g/m 2 is used as the recording material P. As shown in FIG. As described with reference to FIG. 3, the light amount difference decreases as the moisture content of the recording material P increases. The moisture detection control unit 39 is caused to hold moisture determination information such as an equation, a table, etc. showing the relationship in FIG. 4 in advance. Then, the moisture detection control unit 39 determines the moisture content based on the moisture determination information and the light amount difference, which is the evaluation value. In the present embodiment, the moisture content is used as the value indicating the moisture content of the recording material P. However, as the moisture determination information, information indicating the relationship between the amount of light and the moisture content is used to obtain the moisture content. It can be. Further, in the present embodiment, the light amount difference between the transmitted light amount of visible light and near-infrared light is used as the evaluation value, but the present invention is limited to a configuration in which the light amount difference is used as the evaluation value if the value correlates with the water content. not. For example, the evaluation value may be the ratio between the amount of transmitted visible light and the amount of transmitted near-infrared light. That is, the configuration may be such that the light amount ratio expressed by the following formula (4) is used as the evaluation value.
Light quantity ratio = Transmitted light quantity of near-infrared light / Transmitted light quantity of visible light (4)

図５は、本実施形態における含水率の判定処理のフローチャートである。画像形成の開始により、Ｓ１０１で、水分検知制御部３９は、発光素子３７ａ及び３７ｂを発光させる。Ｓ１０２で、制御部１０は、レジストレーションセンサ３により記録材Ｐの搬送位置を検知する。Ｓ１０２での記録材Ｐの検知後、Ｓ１０３で、制御部１０は、所定時間だけ待機する。この待機時間は、記録材Ｐが、発光部３７から受光部３８への光路内の位置より上流側の所定位置に到達するまでの時間である。制御部１０は、Ｓ１０３で所定時間が経過すると、水分検知制御部３９を制御し、Ｓ１０４及びＳ２０４で、可視光及び近赤外光それぞれについて紙無受光量を測定させる。なお、記録材Ｐが発光部３７から受光部３８への光路内に到達する直前の位置で紙無受光量を測定するのは、紙無受光量と紙有受光量の測定時における、発光部３７の発光強度の時間変動の影響を抑えるためである。紙無光量の測定後、Ｓ１０５及びＳ２０５で、制御部１０は、紙有受光量を測定できる位置に記録材Ｐが到達するまでの所定時間だけ待機する。その後、Ｓ１０６及びＳ２０６で、制御部１０は、水分検知制御部３９を制御し、これにより、水分検知制御部３９は、可視光及び近赤外光それぞれについて紙有受光量を測定する。 FIG. 5 is a flow chart of the moisture content determination process in this embodiment. When image formation is started, in S101, the moisture detection control unit 39 causes the light emitting elements 37a and 37b to emit light. In S<b>102 , the control unit 10 detects the conveying position of the recording material P using the registration sensor 3 . After detecting the recording material P in S102, the control unit 10 waits for a predetermined time in S103. This standby time is the time until the recording material P reaches a predetermined position upstream of the position in the optical path from the light emitting unit 37 to the light receiving unit 38 . After a predetermined time has elapsed in S103, the control unit 10 controls the moisture detection control unit 39 to measure the non-light receiving amount of visible light and near-infrared light in S104 and S204. The reason why the amount of light without paper is measured at the position immediately before the recording material P reaches the optical path from the light emitting unit 37 to the light receiving unit 38 is because the amount of light without paper and the amount of light with paper are measured. This is to suppress the influence of the time variation of the emission intensity of 37. After measuring the amount of light without paper, in S105 and S205, the control unit 10 waits for a predetermined time until the recording material P reaches a position where the amount of light received with paper can be measured. After that, in S106 and S206, the control unit 10 controls the moisture detection control unit 39, whereby the moisture detection control unit 39 measures the amount of received light with paper for each of visible light and near-infrared light.

Ｓ１０７及びＳ２０7で、水分検知制御部３９は、可視光及び近赤外光それぞれについて式（１）により透過光量を算出し、Ｓ１０８及びＳ２０８で、可視光及び近赤外光それぞれの透過光量を保存する。Ｓ１０９及びＳ２０９において、制御部１０は、記録材Ｐが紙有受光量を測定できる位置を抜けたかを判定し、抜けていないと、水分検知制御部３９を制御し、紙有受光量の測定と、透過光量の算出と保存を繰り返し行う。記録材Ｐが紙有受光量を測定できる位置を抜けると、水分検知制御部３９は、Ｓ１１０及びＳ１２０において、可視光及び近赤外光それぞれについて測定した複数の透過光量の平均値を求める。Ｓ１１１で、水分検知制御部３９は、可視光及び近赤外光それぞれの透過光量の平均値により評価値を算出する。そして、水分検知制御部３９は、事前に設定された水分判定情報と、評価値とに基づき記録材Ｐの含水率を判定する。 In S107 and S207, the moisture detection control unit 39 calculates the amount of transmitted light for each of the visible light and the near-infrared light by Equation (1), and in S108 and S208, stores the amount of transmitted light for each of the visible light and the near-infrared light. do. In S109 and S209, the control unit 10 determines whether the recording material P has passed the position where the amount of light received with paper can be measured. , the amount of transmitted light is calculated and stored repeatedly. When the recording material P passes through the position where the amount of received light with paper can be measured, the moisture detection control unit 39 obtains an average value of a plurality of transmitted light amounts measured for visible light and near-infrared light in S110 and S120. In S111, the moisture detection control unit 39 calculates an evaluation value based on the average value of the amounts of transmitted light of visible light and near-infrared light. Then, the moisture detection control unit 39 determines the moisture content of the recording material P based on preset moisture determination information and the evaluation value.

以上、本実施形態では、可視光及び近赤外光を射出する光源と、可視光及び近赤外光に感度を有する受光素子により記録材の含水量を示す値を算出する。つまり、水の吸収波長である１４５０ｎｍや１９４０ｎｍに受光感度を有する受光素子を使用することなく記録材の水分量を検知できる。なお、可視光及び近赤外光に感度を有する受光素子は一般的なものであり高価ではない。また、記録材Ｐは、その位置によって厚みや密度にばらつきがあるため、測定位置によって紙有受光量にばらつきが生じ得る。しかしながら、複数回、紙有受光量を検知し、それぞれの紙有受光量の平均値を使用して評価値を求めることで、測定位置による紙有受光量のばらつきを抑え、精度よく水分量に関する値を検出することができる。なお、紙有受光量の検知を複数回に渡り行うのではなく、エリア型センサを用いる等、受光素子３８ａ及び３８ｂの受光面積を広くする構成であっても良い。また、紙無受光量の測定と、紙有受光量の測定とを所定時間内に行うことで、発光素子３７ａ、３７ｂの発光強度の時間変動の影響を抑え、精度よく水分量に関する値を検出することができる。さらに、可視光及び近赤外光それぞれの紙無受光量の測定と、紙有受光量の測定とを並行して行うことで短い時間で精度よく水分量に関する値を検出することができる。 As described above, in the present embodiment, a value indicating the water content of the recording material is calculated using a light source that emits visible light and near-infrared light and a light receiving element that is sensitive to visible light and near-infrared light. That is, the water content of the recording material can be detected without using a light receiving element having light sensitivity at 1450 nm or 1940 nm, which is the absorption wavelength of water. Note that light-receiving elements sensitive to visible light and near-infrared light are common and inexpensive. Further, since the thickness and density of the recording material P vary depending on the position, the amount of received light with paper may vary depending on the measurement position. However, by detecting the amount of received light with paper multiple times and obtaining the evaluation value using the average value of the respective amounts of received light with paper, variations in the amount of received light with paper depending on the measurement position can be suppressed, and the moisture content can be accurately measured. value can be detected. Instead of detecting the amount of received light with paper a plurality of times, it is also possible to employ a configuration in which the light receiving areas of the light receiving elements 38a and 38b are widened, such as by using an area sensor. In addition, by measuring the amount of light received without paper and the amount of light received with paper within a predetermined period of time, the influence of time fluctuations in the light emission intensity of the light emitting elements 37a and 37b is suppressed, and the value related to the moisture content is accurately detected. can do. Furthermore, by measuring the amount of visible light and near-infrared light without receiving light on paper and measuring the amount of light received on paper in parallel, it is possible to accurately detect the moisture content in a short time.

なお、本発明は、発光素子３７ａが可視光を射出し、発光素子３７ｂが近赤外光を射出するものに限定されない。記録材Ｐの含水量の変化による透過光量の変化量が異なる２つの波長であれば、発光素子３７ａ及び発光素子３７ｂ共に可視光、或いは、近赤外光を射出する構成とすることができる。 The present invention is not limited to the light emitting element 37a emitting visible light and the light emitting element 37b emitting near-infrared light. If the two wavelengths have different amounts of change in the amount of transmitted light due to changes in the water content of the recording material P, both the light emitting elements 37a and 37b can be configured to emit visible light or near-infrared light.

＜第二実施形態＞
続いて、第二実施形態について第一実施形態との相違点を中心に説明する。本実施形態では、記録材判別装置３０が検知する記録材Ｐの坪量も水分量に関する値の判定に使用する。 <Second embodiment>
Next, the second embodiment will be described, focusing on differences from the first embodiment. In this embodiment, the basis weight of the recording material P detected by the recording material determination device 30 is also used to determine the value related to the moisture content.

図１に示す記録材判別装置３０の坪量検知部３１は、記録材Ｐの坪量を検知する超音波センサである。坪量検知部３１は、記録材Ｐに超音波を送信する送信部３３と、記録材Ｐを介した超音波を受信する受信部３４とを有し、受信した音波の振幅値により記録材Ｐの坪量を検知する。なお、坪量検知部３１は超音波センサを用いたものに限定されず、記録材の坪量を検知する他のタイプのセンサであっても、坪量と相関が高い記録材の厚み量等を検知するセンサであっても良い。 A basis weight detection unit 31 of the recording material discrimination device 30 shown in FIG. The basis weight detection unit 31 includes a transmission unit 33 that transmits ultrasonic waves to the recording material P, and a reception unit 34 that receives the ultrasonic waves transmitted through the recording material P. Detects the basis weight of Note that the grammage detection unit 31 is not limited to one that uses an ultrasonic sensor, and even if it is a sensor of another type that detects the grammage of the recording material, the thickness of the recording material, which is highly correlated with the grammage, etc., can be detected. It may be a sensor that detects

図６は、記録材Ｐの坪量と、評価値である可視光と近赤外光の透過光量の差、つまり、光量差との関係を示している。図６は、含水率、約２％、約５％、約９％それぞれについて、坪量が６０ｇ／ｍ２（６０ｇ紙）、６８ｇ／ｍ２（６８ｇ紙）、７５ｇ／ｍ２（７５ｇ紙）の普通紙での関係を示している。図６の６０ｇ紙、６８ｇ紙、７５ｇ紙では、記録材Ｐの坪量の変化に伴い、光量差が変化している。そのため、坪量検知部３１により記録材Ｐの坪量を検知し、坪量に応じた、評価値（光量差）と含水率との関係に基づき記録材Ｐの含水率を判定することでより精度よく含水率を判定できる。 FIG. 6 shows the relationship between the grammage of the recording material P and the difference between the transmitted light amounts of visible light and near-infrared light, which is an evaluation value, that is, the light amount difference. FIG. 6 shows the basis weights of 60 g/m 2 (60 g paper), 68 g/m 2 (68 g paper), and 75 g/m 2 (75 g paper) for moisture contents of about 2%, about 5%, and about 9%, respectively. on plain paper. In 60 g paper, 68 g paper, and 75 g paper in FIG. Therefore, the basis weight of the recording material P is detected by the basis weight detection unit 31, and the moisture content of the recording material P is determined based on the relationship between the evaluation value (difference in amount of light) and the moisture content corresponding to the basis weight. Moisture content can be determined with high accuracy.

本実施形態における含水率の判定処理は、基本的には、図５に示す第一実施形態と同様である。ただし、本実施形態では、記録材Ｐが記録材判別装置３０を通過する際に、記録材判別装置３０により記録材Ｐの坪量を判定する。具体的には、送信部３３より記録材Ｐを介して得られる音波を受信部３４で受信し、その振幅値を測定する。記録材判別装置３０は、予め設定されている振幅値と坪量との関係を示す情報に基づき坪量を判定する。そして、本実施形態において、水分判定情報は、図６に示す様な、記録材Ｐの各坪量について、評価値と含水率との関係を示すものとする。そして、水分検知制御部３９は、図５のＳ１１２において、記録材判別装置３０が検知した坪量に対応する水分判定情報と評価値とに基づき含水率を判定する。 The moisture content determination process in this embodiment is basically the same as in the first embodiment shown in FIG. However, in the present embodiment, the basis weight of the recording material P is determined by the recording material determination device 30 when the recording material P passes through the recording material determination device 30 . Specifically, the receiving section 34 receives a sound wave obtained from the transmitting section 33 through the recording material P, and measures the amplitude value of the sound wave. The recording material determination device 30 determines the grammage based on information indicating the relationship between the preset amplitude value and the grammage. In this embodiment, the moisture determination information indicates the relationship between the evaluation value and the moisture content for each basis weight of the recording material P, as shown in FIG. Then, in S112 of FIG. 5, the moisture detection control unit 39 determines the moisture content based on the moisture determination information corresponding to the basis weight detected by the recording material determination device 30 and the evaluation value.

以上、本実施形態では、記録材の坪量を検知することで、坪量に基づいた高精度な記録材の水分検知が可能になる。なお、記録材判別装置３０により坪量を検出するのではなく、ユーザによるタッチパネルやボタン操作等からの入力に基づき坪量を判定する構成であっても良い。 As described above, in the present embodiment, by detecting the basis weight of the recording material, it is possible to detect the water content of the recording material with high accuracy based on the basis weight. Instead of detecting the grammage by the recording material determination device 30, the grammage may be determined based on the user's input from a touch panel, button operation, or the like.

＜第三実施形態＞
続いて、本実施形態について、第一実施形態及び第二実施形態との相違点を中心に説明する。第二実施形態では、記録材判別装置３０の坪量検知部３１により記録材Ｐの坪量を検知していた。本実施形態では、水分検知センサ部３６の発光素子３７ｂが射出する近赤外光により、記録材Ｐの坪量の範囲を検知する。したがって、本実施形態においては、坪量検知部３１を省略することができる。 <Third embodiment>
Next, the present embodiment will be described with a focus on differences from the first embodiment and the second embodiment. In the second embodiment, the basis weight of the recording material P is detected by the basis weight detection unit 31 of the recording material discrimination device 30 . In the present embodiment, the range of basis weight of the recording material P is detected by near-infrared light emitted by the light emitting element 37b of the moisture detection sensor portion 36 . Therefore, in this embodiment, the basis weight detection unit 31 can be omitted.

図７は、近赤外光を記録材Ｐに照射したときの透過光量と坪量との関係を示している。記録材Ｐの坪量と近赤外光の透過光量には相関があり、坪量の増加に従い、透過光量は減少する。なお、透過光量は、記録材Ｐの含水率に応じて増減するものの、坪量の差に起因する増減幅より比較的小さい。そのため、近赤外光の透過光量により記録材Ｐの坪量の凡その値（範囲）を特定できる。 FIG. 7 shows the relationship between the amount of transmitted light and the basis weight when the recording material P is irradiated with near-infrared light. There is a correlation between the basis weight of the recording material P and the amount of transmitted near-infrared light, and the amount of transmitted light decreases as the basis weight increases. Although the amount of transmitted light increases or decreases according to the moisture content of the recording material P, the range of increase or decrease due to the difference in basis weight is relatively small. Therefore, the approximate value (range) of the basis weight of the recording material P can be specified by the amount of transmitted near-infrared light.

本実施形態における含水率の判定処理は、基本的には、図５に示す第一実施形態と同様である。ただし、本実施形態では、水分検知制御部３９に、近赤外光の透過光量と坪量の関係を示す坪量判定情報を予め設定しておく。そして、水分検知制御部３９は、坪量判定情報と、図５のＳ２１０で求めた近赤外光の透過光量の平均値により坪量を判定する。また、水分検知制御部３９には、記録材Ｐの各坪量について、評価値と含水率との関係を示す水分判定情報を設定しておく。そして、水分検知制御部３９は、Ｓ１１２において、近赤外光の透過光量に基づき判定した坪量での水分判定情報に基づき含水率を判定する。 The moisture content determination process in this embodiment is basically the same as in the first embodiment shown in FIG. However, in the present embodiment, basis weight determination information indicating the relationship between the amount of transmitted near-infrared light and the basis weight is preset in the moisture detection control unit 39 . Then, the moisture detection control unit 39 determines the basis weight based on the basis weight determination information and the average value of the amount of transmitted near-infrared light obtained in S210 of FIG. Further, moisture determination information indicating the relationship between the evaluation value and the moisture content for each basis weight of the recording material P is set in the moisture detection control unit 39 . Then, in S112, the moisture detection control unit 39 determines the moisture content based on the moisture determination information based on the basis weight determined based on the amount of transmitted near-infrared light.

以上、本実施形態でも、第二実施形態と同様に、記録材の坪量を考慮することで、精度よく記録材の水分量に関する値を検知できる。また、本実施形態では、坪量検知部３１を不要とすることができる。なお、本実施形態では、近赤外光の透過光量に基づき記録材Ｐの坪量を判定したが、可視光の透過光量に基づき記録材Ｐの坪量を判定することもできる。 As described above, in the present embodiment as well, by considering the basis weight of the recording material, it is possible to accurately detect the water content of the recording material. Further, in the present embodiment, the grammage detection unit 31 can be made unnecessary. Although the basis weight of the recording material P is determined based on the amount of transmitted near-infrared light in the present embodiment, the basis weight of the recording material P can also be determined based on the amount of transmitted visible light.

［その他の実施形態］
本発明は、上述の実施形態の１以上の機能を実現するプログラムを、ネットワーク又は記憶媒体を介してシステム又は装置に供給し、そのシステム又は装置のコンピュータにおける１つ以上のプロセッサがプログラムを読出し実行する処理でも実現可能である。また、１以上の機能を実現する回路（例えば、ＡＳＩＣ）によっても実現可能である。 [Other embodiments]
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

３７：発光部、３８：受光部、３９：水分検知制御部 37: light emitting unit, 38: light receiving unit, 39: moisture detection control unit

Claims (7)

記録材に画像を形成する画像形成手段と、
４００ｎｍから８００ｎｍまでの範囲に含まれるピーク波長をもつ第一の光を記録材に照射する第一の光源と、
前記第一の光のピーク波長よりも長く、８００ｎｍから１０００ｎｍまでの範囲に含まれるピーク波長をもつ第二の光を前記記録材に照射する第二の光源と、
４００ｎｍから１０００ｎｍの範囲に受光感度を有し、前記記録材を透過した前記第一の光と前記第二の光を受光する受光手段と、
前記記録材の坪量に関する情報を取得する取得手段と、
前記受光手段が受光した前記第一の光および前記第二の光と、前記取得手段により取得された前記記録材の坪量に関する情報と、に基づいて、前記画像形成手段が前記記録材に画像を形成する画像形成条件を制御する制御手段と、
を有することを特徴とする画像形成装置。 an image forming means for forming an image on a recording material;
a first light source that irradiates a recording material with a first light having a peak wavelength within a range of 400 nm to 800 nm;
a second light source that irradiates the recording material with a second light having a peak wavelength longer than the peak wavelength of the first light and within a range from 800 nm to 1000 nm;
a light-receiving means having a light-receiving sensitivity in the range of 400 nm to 1000 nm and receiving the first light and the second light transmitted through the recording material;
Acquisition means for acquiring information about the basis weight of the recording material;
The image forming means forms an image on the recording material based on the first light and the second light received by the light receiving means and the information on the basis weight of the recording material acquired by the acquisition means. a control means for controlling image forming conditions for forming
An image forming apparatus comprising: 前記第二の光のピーク波長は８５０ｎｍであることを特徴とする請求項１に記載の画像形成装置。 2. The image forming apparatus according to claim 1, wherein said second light has a peak wavelength of 850 nm. 前記受光手段は、前記第一の光の透過光量と前記第二の光の透過光量に応じた信号を出力することを特徴とする請求項１又は２に記載の画像形成装置。 3. The image forming apparatus according to claim 1, wherein said light receiving means outputs a signal corresponding to the amount of transmitted light of said first light and the amount of transmitted light of said second light. 前記第一の光源、前記第二の光源及び前記受光手段は、前記記録材が搬送される搬送方向において、前記画像形成手段よりも上流側であり、前記記録材が積載される給紙トレイよりも下流側に設けられていることを特徴とする請求項１乃至３のいずれか１項に記載の画像形成装置。 The first light source, the second light source, and the light-receiving means are located upstream of the image forming means in a conveying direction of the recording material, and from a paper feed tray on which the recording material is stacked. 4. The image forming apparatus according to any one of claims 1 to 3, wherein the image forming apparatus is provided on the downstream side. 前記画像形成手段は、前記記録材に画像を転写する転写手段を含み、
前記制御手段は、前記転写手段が前記画像を前記記録材に転写する際の転写電圧又は転写電流を制御することを特徴とする請求項１乃至４のいずれか１項に記載の画像形成装置。 the image forming means includes transfer means for transferring an image onto the recording material;
5. The image forming apparatus according to claim 1, wherein said control means controls transfer voltage or transfer current when said transfer means transfers said image onto said recording material. 前記画像形成手段は、前記記録材に画像を定着させる定着手段を含み、
前記制御手段は、前記定着手段が前記画像を前記記録材に定着させるための定着温度を制御することを特徴とする請求項１乃至５のいずれか１項に記載の画像形成装置。 the image forming means includes fixing means for fixing an image on the recording material;
6. The image forming apparatus according to claim 1, wherein said control means controls a fixing temperature for fixing said image on said recording material by said fixing means. 前記取得手段は、
前記記録材に超音波を送信する送信部と、
前記記録材を通過した前記超音波を受信する受信部と、を有し、
前記受信部が受信した前記超音波に基づいて、前記記録材の坪量に関する情報を取得することを特徴とする請求項１乃至６のいずれか１項に記載の画像形成装置。 The acquisition means is
a transmission unit that transmits ultrasonic waves to the recording material;
a receiving unit that receives the ultrasonic wave that has passed through the recording material;
7. The image forming apparatus according to claim 1, wherein information about the basis weight of the recording material is acquired based on the ultrasonic waves received by the receiving unit.
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