JP2008145514A

JP2008145514A - Image forming apparatus

Info

Publication number: JP2008145514A
Application number: JP2006329604A
Authority: JP
Inventors: Masaru Watanabe; 賢渡邊
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2006-12-06
Filing date: 2006-12-06
Publication date: 2008-06-26

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of detecting an amount of moisture absorption of a recording material as well as the type of the recording material by using a detecting means for detecting the type of the recording material and a fixing means. <P>SOLUTION: The image forming apparatus includes: a paper feed means for feeding recording materials; a conveyance means for conveying the fed recording means; the fixing means for heating the recording material and fixing an image to the recording material; a double-sided printing means for forming images on both sides of the recording material; the detecting means for detecting the type of the recording material conveyed; and a setting means for setting image forming conditions on the basis of the type of the recording material detected by the detecting means for detecting the type of the recording material; and a means for detecting an amount of moisture absorption of the recording material by the detecting means for detecting the recording material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、記録材の種類と、記録材の吸湿量を検出する手段を用いた画像形成装置に関するものである。 The present invention relates to an image forming apparatus using a recording material type and means for detecting the moisture absorption amount of the recording material.

電子写真方式やインクジェット方式などの画像形成装置は、画像形成技術が発達し、フルカラーで画像形成を行えるものも広く普及し始めている。これらの画像形成装置は、例えば電子写真方式においては、記録材にトナーを転写する過程において、感光ドラムや記録材に高電圧を印加している。しかし、記録材の保管条件によって、記録材に含まれる水分量が変化する。記録材は、吸湿した水分量によって静電特性が変化し、画像転写不良を起こしやすくなるため、良質な転写画像を得られない場合がある。そこで、例えば特開昭６１−２６０６０や、特開平６−１５６７７８では、画像形成動作に先立って、吸湿した用紙を加熱するための発熱体が、用紙搬送路経路となるガイド部や、ガイド部の下面に配備され、上記ガイド部を搬送中の記録材に対し、加熱、乾燥を行っている。 As image forming apparatuses such as electrophotographic systems and ink jet systems, image forming techniques have been developed, and those capable of forming full-color images have started to be widely used. In these image forming apparatuses, for example, in electrophotography, a high voltage is applied to the photosensitive drum and the recording material in the process of transferring the toner to the recording material. However, the amount of water contained in the recording material varies depending on the storage conditions of the recording material. The recording material has electrostatic characteristics that change depending on the amount of moisture absorbed and is liable to cause image transfer failure, so that a high-quality transfer image may not be obtained. Therefore, for example, in Japanese Patent Application Laid-Open No. 61-26060 and Japanese Patent Application Laid-Open No. 6-156778, a heating element for heating the moisture-absorbed paper prior to the image forming operation is used as a guide part serving as a paper conveyance path, The recording material provided on the lower surface and transporting the guide portion is heated and dried.

一方、記録材はより広範な種類の画像形成を行うために、様々な種類が開発されている。しかし、様々な種類の記録材に対応して高品質の画像を得るためには、画像形成時の諸条件を最適化する必要がある。 On the other hand, various types of recording materials have been developed in order to form a wider variety of images. However, in order to obtain a high-quality image corresponding to various types of recording materials, it is necessary to optimize various conditions during image formation.

例えば、電子写真方式において記録材上に転写されたトナーを加熱、加圧して記録材に定着させる定着プロセスでは、記録材の種類が異なると、必要となる熱量が異なるため、記録材の種類に基づいて、定着時の温度を制御する必要がある。そこで、例えば特開平７−１３４０２２では、記録材の有無による任意の搬送ローラ間の距離の変化を測定することにより、記録材の厚さを検知している。特開２００３−２９４４０１では、記録材が搬送路に設置したレバー部材を押し上げ、レバー部材の変動量によって、記録材の厚さを検知している。
特開昭６１−２６０６０号公報特開平６−１５６７７８号公報特開平７−１３４０２２号公報特開２００３−２９４４０１号公報 For example, in a fixing process in which toner transferred onto a recording material in an electrophotographic system is heated and pressed to be fixed on the recording material, the amount of heat required differs depending on the type of recording material. Based on this, it is necessary to control the temperature during fixing. Therefore, for example, in Japanese Patent Laid-Open No. 7-134022, the thickness of the recording material is detected by measuring a change in the distance between any conveying rollers depending on the presence or absence of the recording material. In Japanese Patent Application Laid-Open No. 2003-294401, a recording material pushes up a lever member installed in a conveyance path, and the thickness of the recording material is detected based on a fluctuation amount of the lever member.
JP-A 61-26060 JP-A-6-156778 Japanese Patent Laid-Open No. 7-134022 JP 2003-294401 A

上記したように、記録材の吸湿量が多くなると、記録材の静電特性が変化するために、画像不良を起きる可能性がある。この場合、記録材にトナーを転写する過程において、転写電圧の出力範囲を変更することにより、画像転写不良を防ぐことができる。 As described above, when the moisture absorption amount of the recording material increases, the electrostatic characteristics of the recording material change, which may cause image defects. In this case, image transfer failure can be prevented by changing the output range of the transfer voltage in the process of transferring the toner to the recording material.

また、画像形成条件を最適化するためには、記録材の種類を検知する必要がある。しかし、記録材の吸湿量が異なると、記録材の剛性が変化してしまい、記録材の種類を検出する際に影響が出る場合がある。ただし、記録材の吸湿量が既知であれば、記録材の種類を判別するために用いる閾値を変更することにより、記録材の種類を検知することができる。 Further, in order to optimize the image forming conditions, it is necessary to detect the type of recording material. However, if the moisture absorption amount of the recording material is different, the rigidity of the recording material changes, which may affect the detection of the type of the recording material. However, if the moisture absorption amount of the recording material is known, the type of the recording material can be detected by changing the threshold value used to determine the type of the recording material.

しかし、画像形成装置の小型化、コストダウンのためには、新たに記録材を加熱、乾燥する装置を設置することは困難である。 However, in order to reduce the size and cost of the image forming apparatus, it is difficult to install a new apparatus for heating and drying the recording material.

そこで、本発明では、記録材の種類を検知する検知手段と、定着手段を使用し、記録材の種類を検知すると同時に、記録材の吸湿量を検知し、検知した記録材の吸湿量に基づいて画像形成条件を最適化することができる画像形成装置を提供することを目的とする。 Therefore, in the present invention, the detection unit for detecting the type of the recording material and the fixing unit are used to detect the type of the recording material and simultaneously detect the moisture absorption amount of the recording material, and based on the detected moisture absorption amount of the recording material. An object of the present invention is to provide an image forming apparatus capable of optimizing image forming conditions.

本出願にかかる第１の発明では、両面印刷時において、記録材の種類を検知する手段と、定着手段を使用し、両面印刷時１面目、すなわち加熱、乾燥を行う前における上記の検知手段による測定結果と、両面印刷２面目、すなわち加熱・乾燥を行った後における上記の検知手段による測定結果の差を検出し、この検出結果と閾値を比較することにより、記録材の吸湿量の検知を行う。そして、検知した記録材の吸湿量に基づいて、画像形成条件を最適化し、高品質な画像を得ることができる。 In the first invention according to the present application, at the time of double-sided printing, the means for detecting the type of recording material and the fixing means are used, and the above-mentioned detection means is used for the first side at the time of double-sided printing, that is, before heating and drying. By detecting the difference between the measurement result and the second measurement on the second side, that is, the measurement result by the above-mentioned detection means after heating and drying, and comparing the detection result with a threshold value, the moisture absorption amount of the recording material is detected. Do. Then, based on the detected moisture absorption amount of the recording material, the image forming conditions can be optimized and a high quality image can be obtained.

また第２の発明では、第１の発明によって検知した記録材の吸湿量に基づいて、記録材の種類を検知するために用いる閾値を選択することにより、記録材の吸湿量に関わらず、記録材の種類の検知を行う。 In the second invention, the threshold used for detecting the type of the recording material is selected based on the moisture absorption amount of the recording material detected by the first invention, so that the recording material can be recorded regardless of the moisture absorption amount of the recording material. Detect the type of material.

以上説明したように、本発明によれば、新たに記録材を加熱、乾燥させる装置を設置することなく、記録材の種類と吸湿量を検知することができる。その結果、記録材の種類と吸湿量に基づいて、適切な画像形成条件を設定することができ、高品質な画像を得ることができる。 As described above, according to the present invention, the type and moisture absorption amount of the recording material can be detected without installing a new apparatus for heating and drying the recording material. As a result, appropriate image forming conditions can be set based on the type of recording material and the amount of moisture absorption, and a high-quality image can be obtained.

（実施例１）
図１は、本発明の実施例１で使用する画像形成装置の構成を示している。感光ドラム１０１は、帯電ローラ１０２で表面を一様にある極性に帯電された後に、レーザーなどの露光手段１０３によって感光ドラム１０１の露光下領域のみを除電され、潜像が形成される。現像器１０４のトナー１０５は、現像ブレード１０４ａと現像スリーブ１０４ｂの間で感光ドラム１０１の帯電表面と同極性に摩擦帯電される。そして感光ドラム１０１と現像スリーブ１０４ｂが対向する現像ギャップ部に、ＤＣ及びＡＣバイアスを重畳印加することで、トナー１０５は電解の作用により浮遊振動しつつ感光ドラム１０１の潜像形成部に選択的に付着した後に、転写ローラ１０６と感光ドラム１０１の回転によって搬送される。 (Example 1)
FIG. 1 shows the configuration of an image forming apparatus used in Embodiment 1 of the present invention. The surface of the photosensitive drum 101 is uniformly charged to a certain polarity by the charging roller 102, and then only the area under the exposure of the photosensitive drum 101 is neutralized by an exposure unit 103 such as a laser to form a latent image. The toner 105 of the developing device 104 is frictionally charged with the same polarity as the charging surface of the photosensitive drum 101 between the developing blade 104a and the developing sleeve 104b. Then, by applying a DC and AC bias to the developing gap portion where the photosensitive drum 101 and the developing sleeve 104b face each other, the toner 105 is selectively applied to the latent image forming portion of the photosensitive drum 101 while floating and vibrating by the action of electrolysis. After adhering, it is conveyed by the rotation of the transfer roller 106 and the photosensitive drum 101.

一方、記録材は、給紙カセット１０７にセットされており、給紙ローラ１０８によって搬送され、記録材背面の転写ローラ１０６により、トナー１０５と逆極性の高電圧が印加される。高電圧が印加された記録材は、トナー１０５を静電的に記録材側に引き付け、画像を転写する。さらに、記録材裏面は、トナー１０５と逆極性に印加され、転写されたトナー１０５を保持し続けるために転写電荷が付与される。そして、画像を転写された記録材は、定着器１０９によって加熱、加圧されることにより、画像を定着させ、ＦＤローラ１１０によって排紙される。 On the other hand, the recording material is set in a paper feeding cassette 107, conveyed by a paper feeding roller 108, and a high voltage having a polarity opposite to that of the toner 105 is applied by a transfer roller 106 on the back surface of the recording material. The recording material to which the high voltage is applied electrostatically attracts the toner 105 to the recording material side to transfer the image. Further, the reverse surface of the recording material is applied with a polarity opposite to that of the toner 105, and a transfer charge is applied to keep the transferred toner 105 held. The recording material to which the image has been transferred is heated and pressed by the fixing device 109 to fix the image, and is discharged by the FD roller 110.

両面印刷の場合、記録材の後端が、排紙センサ１１１を通過してから一定時間後に、ＦＤローラ１１０が逆回転を行う。この動作により、記録材は両面搬送路に搬送され、再給紙ローラ１１２によって再び給紙され、再度、画像形成を行う。 In the case of double-sided printing, the FD roller 110 rotates in the reverse direction after a certain period of time after the trailing edge of the recording material passes through the paper discharge sensor 111. By this operation, the recording material is conveyed to the double-sided conveyance path, is again fed by the refeed roller 112, and image formation is performed again.

図２は、本実施例で使用する記録材厚さ検出手段１１３を示している。レバー２０１は回転軸２０２と軸受け２０３により、搬送路に固定されている。レバー２０１は、記録材が搬送されると、記録材の厚さの分だけ押し上げられる。そして、記録材が通過すると、加圧バネ２０４により記録材が通過する前の状態に戻る。記録材の厚さとレバー２０１の変動量の関係は、以下の式１１４で表される。 FIG. 2 shows the recording material thickness detecting means 113 used in this embodiment. The lever 201 is fixed to the conveyance path by a rotating shaft 202 and a bearing 203. The lever 201 is pushed up by the thickness of the recording material when the recording material is conveyed. When the recording material passes, the pressure spring 204 returns to the state before the recording material passes. The relationship between the thickness of the recording material and the amount of fluctuation of the lever 201 is expressed by the following expression 114.

ただし
y：変位検出装置が検出するレバー変動量[mm]
s：記録材の厚さ[mm]
l：回転軸から検出装置までの水平方向の距離[mm]
L：回転軸から搬送路までのレバーの長さ[mm]
h：搬送路の厚さ[mm]
とする。画像形成装置は、レバー２０１の変動を変位検出装置２０６により検出する。しかし、搬送されている記録材は、搬送路から浮いた状態となっており、記録材の剛性によって、レバーの挙動が変化する。記録材の剛性は、吸湿量により変化するため、同じ記録材でも、吸湿量によってレバーの変動が異なる。

However,
y: Lever fluctuation amount detected by the displacement detector [mm]
s: Recording material thickness [mm]
l: Horizontal distance from the rotation axis to the detector [mm]
L: Length of lever from the rotation axis to the transport path [mm]
h: Thickness of transport path [mm]
And The image forming apparatus detects the fluctuation of the lever 201 by the displacement detection device 206. However, the recording material being conveyed is in a state of floating from the conveyance path, and the behavior of the lever changes depending on the rigidity of the recording material. Since the rigidity of the recording material changes depending on the amount of moisture absorption, even with the same recording material, the lever varies depending on the amount of moisture absorption.

以上説明した記録材厚さ検出手段を備えた画像形成装置を用いて、本出願にかかる第１の発明を説明する。 The first invention according to the present application will be described using the image forming apparatus provided with the recording material thickness detecting means described above.

本実施例における画像形成装置の動作を、図３を用いて説明する。Ｓ３０１では、搬送されている記録材によって変動したレバーの変動量の測定を行い、紙種検知を行う。Ｓ３０２では、一枚目か、二枚目以降かを判別し、二枚目以降の場合は、Ｓ３０３で、Ｓ３０７で検知した記録材の吸湿量に基づき、転写電圧や帯電電圧などの高圧出力範囲、出力レベルを最適化し、Ｓ３０４で、画像形成を行う。そして、Ｓ３０５で両面一面目か、二面目の判断を行う。両面一面目の場合、Ｓ３０６で反転動作を行い、再び、Ｓ３０１で紙種検知を行う。両面二面目の場合は、Ｓ３０７で吸湿量の検知を行う。吸湿量の検知は、一回目と、二回目の紙種検知で行ったレバーの変動量の測定結果y1、y2の差dを算出し、差dが閾値dthよりも大きい場合は、吸湿紙、それ以外の場合は、開直紙として判断する。そして、Ｓ３０８では、次の記録材に対する画像形成を行うか判断を行い、画像形成を続ける場合には、再びＳ３０１の処理を行う。 The operation of the image forming apparatus in this embodiment will be described with reference to FIG. In S301, the amount of change of the lever that has fluctuated depending on the recording material being conveyed is measured, and the paper type is detected. In S302, it is determined whether it is the first sheet or the second sheet. In the case of the second sheet or later, in S303, based on the moisture absorption amount of the recording material detected in S307, a high voltage output range such as a transfer voltage or a charging voltage is obtained. The output level is optimized, and image formation is performed in S304. In step S305, the first side or the second side is determined. In the case of the first side of both sides, the reverse operation is performed in S306, and the paper type is detected again in S301. In the case of the second side of both sides, the moisture absorption amount is detected in S307. The detection of the amount of moisture absorption calculates the difference d between the measurement results y1 and y2 of the lever fluctuation amount performed in the first and second paper type detection, and if the difference d is greater than the threshold dth, In other cases, it is determined as open paper. In S308, it is determined whether or not image formation is to be performed on the next recording material. If image formation is to be continued, the processing in S301 is performed again.

本実施例では、吸湿量を検知する際に用いる閾値を1つとしたが、閾値を複数にして、吸湿量の度合いをより詳細に検知し、画像形成における高圧出力範囲を、記録材の吸湿量の段階に応じて、より詳細に切り替えることも可能である。 In this embodiment, one threshold is used when detecting the amount of moisture absorption, but a plurality of thresholds are used to detect the degree of moisture absorption in more detail, and the high-pressure output range in image formation is the amount of moisture absorption of the recording material. It is also possible to switch in more detail depending on the stage.

（実施例２）
本出願にかかる第２の発明について、図４を用いて説明する。なお、装置構成は実施例１に記載のものを用いる。Ｓ３０１では、搬送されている記録材によって変動したレバーの変動量の測定を行い、紙種検知を行う。Ｓ３０２では、一枚目か、二枚目以降かを判別し、二枚目以降の場合は、Ｓ４０１で、検知した記録材の種類に応じて目標温調温度を最適化し、Ｓ３０４で画像形成を行う。そして、Ｓ３０５で両面一面目か、二面目の判断を行う。両面一面目の場合、Ｓ３０６で反転動作を行い、再び、Ｓ３０１で紙種検知を行う。両面二面目の場合は、Ｓ３０７で吸湿量の検知を行う。吸湿量の検知は、一回目と、二回目の紙種検知で行ったレバーの変動量の測定結果y1、y2の差dを算出し、差dが閾値dthよりも大きい場合は、吸湿紙、それ以外の場合は、開直紙として判断する。そして、Ｓ４０２では、検出した記録材の吸湿量に基づいて、記録材の種類の検知に用いる閾値テーブルPthを切り替え、記録材の種類の検知精度を向上させる。そして、Ｓ３０８では、次の記録材に対する画像形成を行うか判断を行い、画像形成を続ける場合には、再びＳ３０１の処理を行う。 (Example 2)
A second invention according to the present application will be described with reference to FIG. The apparatus configuration described in the first embodiment is used. In S301, the amount of change of the lever that has fluctuated depending on the recording material being conveyed is measured, and the paper type is detected. In S302, it is determined whether it is the first sheet or the second sheet. In the case of the second sheet or later, in S401, the target temperature adjustment temperature is optimized according to the type of the detected recording material, and image formation is performed in S304. Do. In step S305, the first side or the second side is determined. In the case of the first side of both sides, the reverse operation is performed in S306, and the paper type is detected again in S301. In the case of the second side of both sides, the moisture absorption amount is detected in S307. The detection of the amount of moisture absorption calculates the difference d between the measurement results y1 and y2 of the lever fluctuation amount performed in the first and second paper type detection, and if the difference d is greater than the threshold dth, In other cases, it is determined as open paper. In S402, based on the detected moisture absorption amount of the recording material, the threshold value table Pth used for detecting the recording material type is switched to improve the recording material type detection accuracy. In S308, it is determined whether or not image formation is to be performed on the next recording material. If image formation is to be continued, the processing in S301 is performed again.

本実施例では、吸湿量を検知する際に用いる閾値を1つとしたが、閾値を複数にして、吸湿量の度合いをより詳細に検知し、記録材の種類を検知するために用いる閾値を、記録材の吸湿量の段階に応じてより詳細に切り替えることも可能である。 In this embodiment, the threshold used for detecting the amount of moisture absorption is one, but the threshold is used in a plurality to detect the degree of moisture absorption in more detail, and the threshold used to detect the type of recording material, It is also possible to switch in more detail according to the level of moisture absorption of the recording material.

実施例１で用いる使用する画像形成装置の構成図。1 is a configuration diagram of an image forming apparatus used in Embodiment 1. FIG. 実施例１で用いる記録材厚さ検出手段の側面図。3 is a side view of recording material thickness detection means used in Embodiment 1. FIG. 実施例１の制御を示すフローチャート。3 is a flowchart illustrating control according to the first embodiment. 実施例２の制御を示すフローチャート。10 is a flowchart illustrating control according to the second embodiment.

符号の説明Explanation of symbols

１０２帯電ローラ
１０４ｂ現像ローラ
１０６転写ローラ
１１３記録材の種類を検知する手段 102 Charging roller 104b Developing roller 106 Transfer roller 113 Means for detecting type of recording material

Claims

記録材を給紙する給紙手段と、給紙された記録材を搬送する搬送手段と、記録材を加熱し、画像を記録材に定着させる定着手段と、記録材の両面に画像を形成する両面印刷手段と、搬送された記録材の種類を検出する検出手段と、前記記録材の種類を検出する検出手段により検出した記録材の種類に基づき画像形成条件を設定する画像形成装置において、前記記録材の種類を検知する検出手段を用いて、両面1面目の画像形成時と、両面２面目の画像形成時に、記録材の種類の検出を行い、測定結果の差分から、記録材の吸湿量を検知し、記録材の吸湿量に基づいて、画像形成条件を設定することを特徴とする画像形成装置。 An image is formed on both sides of the recording material, a paper feeding device that feeds the recording material, a conveying device that transports the fed recording material, a fixing device that heats the recording material and fixes the image to the recording material In the image forming apparatus that sets the image forming condition based on the type of recording material detected by the double-sided printing unit, the detecting unit that detects the type of the conveyed recording material, and the detecting unit that detects the type of the recording material, The detection means for detecting the type of recording material is used to detect the type of recording material at the time of image formation on the first and second surfaces, and from the difference in measurement results, the amount of moisture absorbed by the recording material And an image forming condition is set based on the moisture absorption amount of the recording material.

記録材の種類と吸湿量に基づいて、記録材の種類を判別するために用いる閾値を切り替え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 a threshold used for determining the type of the recording material is switched based on the type of the recording material and the moisture absorption amount.