JP2008096780A

JP2008096780A - Image forming apparatus and process cartridge

Info

Publication number: JP2008096780A
Application number: JP2006279736A
Authority: JP
Inventors: Takashi Sakamaki; 崇酒巻; Yosuke Saito; 洋輔西東
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2006-10-13
Filing date: 2006-10-13
Publication date: 2008-04-24
Anticipated expiration: 2026-10-13
Also published as: JP5207098B2; CN101162376B; CN101162376A

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a fixing offset caused by initial developer, by adjusting toner concentration of the initial developer in a developing device of an image forming apparatus that recycles toner. <P>SOLUTION: The image forming apparatus includes: a photoreceptor 1; a developing device 2 storing toner and carrier; a transfer means; a fixing device; a cleaning device 7; a collected toner conveying path 15 along which toner collected by the cleaning device 7 is conveyed to the developing device; and a control means for controlling them. In the image forming apparatus, control is performed as described below. If a new developing device detecting means detects a new developing device, a toner consumption pattern forming means forms a toner consumption pattern on the photoreceptor, the cleaning device collects the toner consumption pattern, and the toner in the developing device 2 is forcibly consumed while the collected toner is stored in a collected toner storage means 10a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、複写機、ファクシミリ、プリンタ等の画像形成装置、及び、これに採用されるプロセスカートリッジに関するものである。 The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and a process cartridge employed in the image forming apparatus.

上記画像形成装置では、着荷時または現像装置の交換時に、初期現像剤による定着オフセットという問題が発生する場合があった。着荷または交換されたばかりの新品の現像装置のなかには、それまでに長期あるいは高温高湿環境下に放置されたものがあり、この放置の影響により現像装置に収容された初期現像剤のトナーが帯電し難くなりトナー帯電量が低下してしまう。トナー帯電量が低下してしまうと感光体へのトナー付着量が過多となり、これに伴い転写紙などの記録媒体上のトナー付着量も過多となる。このとき、定着装置の定着能力にあまり余裕がない場合には、付着量過多となったトナーを記録媒体に定着しきれず、定着しきれなかったトナーが定着装置の加圧ローラに付着してしまう。これが、初期現像剤による定着オフセットである。 In the image forming apparatus, there is a case where a problem of fixing offset due to the initial developer occurs when the image forming apparatus arrives or the developing apparatus is replaced. Some new developing devices that have just arrived or replaced have been left in a long-term or high-temperature, high-humidity environment, and the toner of the initial developer housed in the developing device is charged by the influence of this leaving. It becomes difficult and the toner charge amount decreases. When the toner charge amount decreases, the toner adhesion amount on the photoreceptor becomes excessive, and accordingly, the toner adhesion amount on the recording medium such as transfer paper also becomes excessive. At this time, if the fixing device does not have a sufficient fixing capability, the toner having an excessive amount cannot be fixed onto the recording medium, and the toner that cannot be fixed adheres to the pressure roller of the fixing device. . This is the fixing offset by the initial developer.

このような初期現像剤による定着オフセットを防止するためには、着荷時または現像装置の交換時に現像装置内の現像剤のトナー濃度を下げ、トナー帯電量を上昇させて感光体へのトナー付着量を下げ、これにより記録媒体上のトナー付着量を下げることが考えられる。 In order to prevent such a fixing offset due to the initial developer, the toner concentration of the developer in the developing device is lowered at the time of arrival or replacement of the developing device, and the toner charge amount is increased to increase the toner adhesion amount on the photoreceptor. It is conceivable to lower the toner adhesion amount on the recording medium.

本出願人は、特許文献１、特許文献２、特許文献３等で、現像装置内の現像剤のトナーを強制消費させてトナー濃度を下げる画像形成装置を開示している。これらの画像形成装置では、トナー消費用パターンを感光体上に形成し、これをクリーニング装置で回収することにより、現像装置内のトナーを強制消費させてトナー濃度を下げている。 The present applicant discloses an image forming apparatus in Patent Document 1, Patent Document 2, Patent Document 3, and the like that forcibly consumes developer toner in a developing device to lower the toner density. In these image forming apparatuses, a toner consumption pattern is formed on a photosensitive member, and this is collected by a cleaning device, whereby the toner in the developing device is forcibly consumed to lower the toner concentration.

特開平４−１５８３８２号公報JP-A-4-158382 特許第３７９３６５４号公報Japanese Patent No. 3793654 特許第３７９３６５５号公報Japanese Patent No. 3793655

近年、クリーニング装置で回収したトナーを回収トナー搬送路を通じて現像装置に戻して再使用する、いわゆるトナーリサイクルをおこなう画像形成装置が多くなってきている。このようなトナーリサイクルをおこなう装置で、上記トナーの強制消費によるトナー濃度調整をおこなおうとしても、回収されたトナーは回収トナー搬送路を通じて現像装置に戻ってしまう。そこで、初期現像剤のトナー濃度を下げることが難しくなってしまう。このため、初期現像剤による定着オフセットを防止することが困難となっている。 In recent years, an increasing number of image forming apparatuses perform so-called toner recycling in which toner collected by a cleaning device is returned to a developing device through a collected toner conveyance path and reused. Even if the toner concentration is adjusted by the forced consumption of the toner in the toner recycling apparatus, the collected toner returns to the developing device through the collected toner conveyance path. Therefore, it becomes difficult to lower the toner concentration of the initial developer. For this reason, it is difficult to prevent fixing offset due to the initial developer.

本発明は、以上の背景に鑑みなされたものであり、その目的とするところは、トナーリサイクルをおこなう画像形成装置において、現像装置内の初期現像剤のトナー濃度を調整して初期現像剤による定着オフセットを防止することのできる画像形成装置およびプロセスカートリッジを提供することである。 The present invention has been made in view of the above background, and an object of the present invention is to fix the toner concentration of the initial developer in the developing device by adjusting the toner concentration in the developing device in an image forming apparatus that performs toner recycling. To provide an image forming apparatus and a process cartridge capable of preventing offset.

上記目的を達成するために、請求項１の発明は、潜像を担持する像担持体と、トナー及びキャリアを含有する二成分現像剤を用いて該潜像をトナー像化する現像装置と、該現像装置内の二成分現像剤にトナーを補給するトナー補給手段と、該像担持体上のトナー像を記録媒体上へ直接的または間接的に転写する転写手段と、該記録媒体上の未定着トナー像を定着する定着装置と、該像担持体上の転写残トナーをクリーニングして回収するクリーニング手段と、該クリーニング手段により回収されたトナーを該現像装置に搬送する回収トナー搬送路と、これらを制御する制御手段とを備え、任意のタイミングで該現像装置を新品に交換する画像形成装置において、上記現像装置が新品か否かを検知する現像装置新品検知手段と、該現像装置により上記像担持体上に所定のトナー消費用パターンを形成するトナー消費用パターン形成手段と、上記クリーニング手段により回収されたトナーを貯留する回収トナー貯留手段とを備え、上記制御手段が、該現像装置新品検知手段により該現像装置が新品と検知された場合に、該トナー消費用パターン形成手段により該像担持体上にトナー消費用パターンを形成し、該トナー消費用パターンを該クリーニング手段により回収し、該回収トナーを該回収トナー貯留手段に貯留することにより、強制的に該現像装置内のトナーを消費させる強制トナー消費動作を実行するよう制御することを特徴とするものである。
また、請求項２の発明は、請求項１の画像形成装置において、上記強制トナー消費動作の実行の可否を外部より選択できる選択手段を設け、上記制御部が、上記強制トナー消費動作の実行前に該選択手段の選択結果に基づき該強制トナー消費動作の実行の要不要を判断し、該判断結果に基づき該強制トナー消費動作を実行するよう制御することを特徴とするものである。
また、請求項３の発明は、請求項１または２の画像形成装置において、上記現像装置の交換時に該現像装置に収容される二成分現像剤の製造年月日を識別できる情報を外部より入力する現像剤情報入力手段を設け、上記制御部が、上記強制トナー消費動作の実行前に該現像剤情報入力手段により入力された情報に基づき現像剤の製造年月日を識別して該強制トナー消費動作の実行の要不要を判断し、該判断結果に基づき該強制トナー消費動作を実行するよう制御することを特徴とするものである。
また、請求項４の発明は、請求項１または２の画像形成装置において、上記現像装置が収容される二成分現像剤の製造年月日を識別できる現像剤情報識別部材を有しており、上記制御部が、上記強制トナー消費動作の実行前に該現像剤情報識別部材より現像剤の製造年月日を識別して該強制トナー消費動作の実行の要不要を判断し、該判断結果に基づき該強制トナー消費動作を実行するよう制御することを特徴とするものである。
また、請求項５の発明は、請求項１、２、３または４の画像形成装置において、上記現像装置により上記像担持体上の所定位置にトナー付着量検出パターンを形成するトナー付着量検出パターン形成手段と、該トナー付着量検出パターンのトナー付着量を検出するトナー付着量検出手段とを備え、上記制御部が、上記強制トナー消費動作の実行前に、該トナー付着量検出パターン形成手段によるトナー付着量検出パターンの形成と、該トナー付着量検出手段による該トナー付着量検出パターンのトナー付着量の検出とを行い、該トナー付着量検出手段による検出結果が所定の目標値となった場合に該強制トナー消費動作の実行しないように制御することを特徴とするものである。
また、請求項６の発明は、請求項５の画像形成装置において、上記制御部が、上記強制トナー消費動作の実行と、該強制トナー消費動作の実行を判断するためにおこなう上記トナー付着量検出手段による上記トナー付着量検出パターンのトナー付着量検出動作とを、交互におこなうよう制御することを特徴とするものである。
また、請求項７の発明は、請求項６の画像形成装置において、上記制御部が、上記強制トナー消費動作の実行と、該強制トナー消費動作の実行を判断するためにおこなう上記トナー付着量検出手段による上記トナー付着量検出パターンのトナー付着量検出動作とを、複数回おこなうよう制御することを特徴とするものである。
また、請求項８の発明は、請求項５、６または７の画像形成装置において、上記制御部が、上記トナー付着量検出手段が上記トナー付着量検出パターンのトナー付着量検出値（Ｖｓｐ）と、トナー付着量検出パターン部以外の像担持体部分のトナー付着量検出値（Ｖｓｇ）とを検出し、これらの比率（Ｖｓｐ／Ｖｓｇ）が所定の値以上となったとき、検出結果が所定の目標値となったと判断することを特徴とするものである。
また、請求項９の発明は、請求項８の画像形成装置において、上記制御部が、上記比率（Ｖｓｐ／Ｖｓｇ）が所定の値以下でも、上記強制トナー消費動作の実行の回数に基づき該強制トナー消費動作の実行を強制的に終了するように制御することを特徴とするものである。
また、請求項１０の発明は、請求項１、２、３、４、５、６、７、８または９の画像形成装置において、上記回収トナー搬送路に開閉可能なシャッターを設け、上記強制トナー消費動作を実行中は該シャッターを閉じることを特徴とするものである。
また、請求項１１の発明は、請求項１、２、３、４、５、６、７、８、９または１０の画像形成装置において、上記トナー消費用パターン形成手段により上記像担持体上に形成されるトナー消費用パターンが、主走査方向に長く、副走査方向に短い長方形を複数、副走査方向に間隔をもって配置したものであることを特徴とするものである。
また、請求項１２の発明は、請求項１１の画像形成装置において、上記像担持体の転写位置よりも下流でクリーニング位置よりも上流の領域に接触する分離手段を備え、上記トナー消費用パターンの主走査方向の該分離手段に対応する位置に間隔を設け、該トナー消費用パターンが該分離手段に接触しないようにしたことを特徴とするものである。
また、請求項１３の発明は、請求項１、２、３、４、５、６、７、８、９、１０、１１または１２の画像形成装置において、上記制御部が、上記現像装置新品検知手段により該現像装置が新品と検知された場合におこなう新品現像装置の立ち上げ動作中に、上記強制トナー消費動作を実行するよう制御することを特徴とするものである。
また、請求項１４の発明は、像担持体と、現像装置と、クリーニング手段とを一体的に支持して形成し、画像形成装置に脱着可能なプロセスカートリッジであって、上記請求項１、２、３、４、５、６、７、８、９、１０、１１、１２または１３の画像形成装置に採用されることを特徴とするものである。 In order to achieve the above object, the invention of claim 1 includes an image carrier that carries a latent image, a developing device that converts the latent image into a toner image using a two-component developer containing toner and carrier, and A toner replenishing unit for replenishing toner to the two-component developer in the developing device; a transfer unit for directly or indirectly transferring the toner image on the image carrier onto the recording medium; A fixing device for fixing a received toner image, a cleaning unit for cleaning and recovering transfer residual toner on the image carrier, a recovery toner transport path for transporting the toner recovered by the cleaning unit to the developing device, A developing means for detecting whether or not the developing device is new, and an image forming apparatus that replaces the developing device with a new one at an arbitrary timing. A toner consumption pattern forming unit that forms a predetermined toner consumption pattern on the image carrier, and a recovered toner storage unit that stores the toner recovered by the cleaning unit, wherein the control unit includes the developing device. When the developing device is detected as new by the new article detecting means, the toner consuming pattern forming means forms a toner consuming pattern on the image carrier, and the toner consuming pattern is collected by the cleaning means. The forgoing toner consumption operation for forcibly consuming the toner in the developing device is performed by storing the collected toner in the collected toner storage means.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, there is provided selection means capable of selecting from the outside whether or not the forced toner consumption operation can be performed, and the control unit performs before the forced toner consumption operation is performed. In addition, it is determined whether or not the forced toner consumption operation needs to be executed based on the selection result of the selection unit, and the forced toner consumption operation is controlled based on the determination result.
According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect, information for identifying the date of manufacture of the two-component developer stored in the developing device when the developing device is replaced is input from the outside. Developer information input means for identifying the developer production date based on the information input by the developer information input means prior to the execution of the forced toner consumption operation. It is characterized by determining whether or not it is necessary to execute the consumption operation, and controlling to execute the forced toner consumption operation based on the determination result.
Further, the invention of claim 4 has a developer information identification member capable of identifying the date of manufacture of the two-component developer in which the developing device is accommodated in the image forming apparatus of claim 1 or 2, The control unit identifies the date of manufacture of the developer from the developer information identification member before executing the forced toner consumption operation, determines whether the execution of the forced toner consumption operation is necessary, and determines the determination result. Based on this, the forced toner consumption operation is controlled to be executed.
According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third, or fourth aspect, a toner adhesion amount detection pattern is formed by the developing device at a predetermined position on the image carrier. Forming means, and toner adhesion amount detection means for detecting the toner adhesion amount of the toner adhesion amount detection pattern, wherein the control unit uses the toner adhesion amount detection pattern formation means before executing the forced toner consumption operation. When the toner adhesion amount detection pattern is formed and the toner adhesion amount of the toner adhesion amount detection pattern is detected by the toner adhesion amount detection means, and the detection result by the toner adhesion amount detection means reaches a predetermined target value. In addition, the forced toner consumption operation is controlled not to be executed.
According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the controller controls the execution of the forced toner consumption operation and the toner adhesion amount detection performed to determine execution of the forced toner consumption operation. The toner adhesion amount detection operation of the toner adhesion amount detection pattern by the means is controlled to be performed alternately.
According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the control unit performs the forced toner consumption operation and the toner adhesion amount detection performed to determine execution of the forced toner consumption operation. The toner adhesion amount detection operation of the toner adhesion amount detection pattern by the means is controlled to be performed a plurality of times.
According to an eighth aspect of the present invention, in the image forming apparatus according to the fifth, sixth, or seventh aspect, the control unit causes the toner adhesion amount detection means to detect a toner adhesion amount detection value (Vsp) of the toner adhesion amount detection pattern. The toner adhesion amount detection value (Vsg) of the image carrier portion other than the toner adhesion amount detection pattern portion is detected, and when the ratio (Vsp / Vsg) exceeds a predetermined value, the detection result is a predetermined value. It is characterized by determining that the target value has been reached.
The invention according to claim 9 is the image forming apparatus according to claim 8, wherein the control unit performs the forced toner consumption operation based on the number of executions of the forced toner consumption operation even when the ratio (Vsp / Vsg) is equal to or less than a predetermined value. Control is performed so as to forcibly end the execution of the toner consumption operation.
According to a tenth aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, fifth, sixth, seventh, eighth, or ninth aspect, a shutter that can be opened and closed is provided in the collected toner conveyance path, and the forced toner is provided. The shutter is closed during the consumption operation.
According to an eleventh aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, or tenth aspect, the toner consuming pattern forming means causes the toner consumption pattern forming means to be placed on the image carrier. The formed toner consumption pattern is characterized in that a plurality of rectangles that are long in the main scanning direction and short in the sub scanning direction are arranged at intervals in the sub scanning direction.
According to a twelfth aspect of the present invention, in the image forming apparatus according to the eleventh aspect of the invention, the image forming apparatus further comprises separation means that contacts a region downstream of the transfer position of the image carrier and upstream of the cleaning position. An interval is provided at a position corresponding to the separating unit in the main scanning direction so that the toner consumption pattern does not contact the separating unit.
According to a thirteenth aspect of the present invention, in the image forming apparatus of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, or twelfth aspect, the control unit detects the new developing device. The forced toner consumption operation is controlled to be executed during the start-up operation of the new developing device performed when the developing device is detected as new by the means.
According to a fourteenth aspect of the present invention, there is provided a process cartridge which is formed by integrally supporting an image carrier, a developing device, and a cleaning means, and is detachable from the image forming apparatus. 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13 image forming apparatus.

本発明においては、クリーニング手段により回収されたトナーを現像装置に戻してトナーリサイクルをおこなう装置において、現像装置が新品と検知された場合には、回収トナー貯留手段が回収トナーを貯留することにより、一時的に回収トナーを現像装置に戻さない状態として、上記強制トナー消費動作を実行する。このような強制トナー消費動作の実行により、現像装置内のトナー濃度を下げることが可能となる。よって、初期現像剤のトナー帯電量を上昇させ、像担持体へのトナー付着量を抑え、記録媒体上のトナー付着量を下げることができる。これにより、トナーリサイクルをおこなう画像形成装置においても、初期現像剤による定着オフセットを防止することができる。 In the present invention, in the apparatus that returns the toner collected by the cleaning unit to the developing device and performs toner recycling, when the developing device is detected as new, the collected toner storing unit stores the collected toner, The forced toner consumption operation is executed in a state where the collected toner is not temporarily returned to the developing device. By executing such forced toner consumption operation, the toner density in the developing device can be lowered. Accordingly, the toner charge amount of the initial developer can be increased, the toner adhesion amount on the image carrier can be suppressed, and the toner adhesion amount on the recording medium can be decreased. Accordingly, even in an image forming apparatus that performs toner recycling, fixing offset due to the initial developer can be prevented.

以上、本発明によれば、トナーリサイクルをおこなう画像形成装置において、現像装置内の初期現像剤のトナー濃度を調整して初期現像剤による定着オフセットを防止することができるという優れた効果がある。 As described above, according to the present invention, in the image forming apparatus that performs toner recycling, there is an excellent effect that the toner concentration of the initial developer in the developing device can be adjusted to prevent the fixing offset due to the initial developer.

以下、本発明を画像形成装置に適用した一実施形態について説明する。まず、本実施形態に係る画像形成装置の構成及び動作について説明する。図１は、本実施形態に係る画像形成装置の像担持体周辺の概略構成をしめす断面図である。この画像形成装置では、像担持体であるドラム状の感光体１の周囲に、帯電ローラ４を備えた帯電装置、レーザー光３を照射する光書込装置、現像装置２、転写ベルト１４、クリーニングブレード６を備えたクリーニング装置７、除電ランプ５等が順に配設されている。この感光体１、帯電ローラ４、現像装置２、クリーニング装置７等は、寿命により新品と交換して使用するよう本体に脱着可能な構成となっている。なお、本実施形態の画像形成装置では、感光体１と、現像装置２と、帯電ローラ４と、クリーニング装置７とが一体的に支持されるように形成され、画像形成装置本体に脱着可能なプロセスカートリッジの形態をなしている。 Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus will be described. First, the configuration and operation of the image forming apparatus according to the present embodiment will be described. FIG. 1 is a cross-sectional view showing a schematic configuration around the image carrier of the image forming apparatus according to the present embodiment. In this image forming apparatus, a charging device provided with a charging roller 4 around a drum-shaped photoconductor 1 as an image carrier, an optical writing device that irradiates a laser beam 3, a developing device 2, a transfer belt 14, and a cleaning device. A cleaning device 7 provided with a blade 6, a charge removal lamp 5, and the like are sequentially disposed. The photosensitive member 1, the charging roller 4, the developing device 2, the cleaning device 7 and the like are configured to be detachable from the main body so that they can be replaced with new ones due to their lifetime. In the image forming apparatus of this embodiment, the photosensitive member 1, the developing device 2, the charging roller 4, and the cleaning device 7 are formed so as to be integrally supported, and can be attached to and detached from the image forming apparatus main body. It is in the form of a process cartridge.

図中矢印方向に回転する感光体１は、帯電ローラ４により表面を一様に帯電され、レーザー光３を照射されることにより、表面に静電潜像を形成される。感光体１上の静電潜像は、現像装置２によりトナーを供給され、静電潜像がトナー像化される。感光体１上のトナー像は転写ベルト１４に搬送される記録媒体としての転写紙上に転写され、図示せぬ定着装置にて定着され、画像形成が行われる。一方、感光体１表面は、クリーニング装置７のクリーニングブレード６により転写残トナーを除去され、除電ランプ５にて除電され、次の画像形成に備える。 The surface of the photoreceptor 1 rotating in the direction of the arrow is uniformly charged by a charging roller 4 and irradiated with a laser beam 3 to form an electrostatic latent image on the surface. The electrostatic latent image on the photoreceptor 1 is supplied with toner by the developing device 2, and the electrostatic latent image is converted into a toner image. The toner image on the photosensitive member 1 is transferred onto a transfer sheet as a recording medium conveyed to the transfer belt 14, and is fixed by a fixing device (not shown) to form an image. On the other hand, the transfer residual toner is removed from the surface of the photoreceptor 1 by the cleaning blade 6 of the cleaning device 7, and the charge is removed by the charge removal lamp 5 to prepare for the next image formation.

また、上記画像形成に伴う現像装置２内のトナー消費を補うために、トナー補給手段（図示せず）が設けられており、以下のようなトナー補給が行われる。画像形成装置は、現像装置２内の現像剤のトナー濃度を検出するトナー濃度検出手段（以下、Ｔセンサという）を備えている。画像形成により現像装置２内のトナーが消費されると、Ｔセンサ（図示せず）により現像装置２内のトナー濃度を検出し、トナー濃度に応じた値の電圧を出力する。画像形成装置の制御部には、予めＴセンサの出力についてＴ目標値が格納されており、このＴ目標値と、実際のＴセンサからの出力とに基づき、現像装置２内のトナー不足分を補うようにトナー補給がされる。 A toner replenishing means (not shown) is provided to supplement the toner consumption in the developing device 2 due to the image formation, and the following toner replenishment is performed. The image forming apparatus includes a toner concentration detection unit (hereinafter referred to as a T sensor) that detects the toner concentration of the developer in the developing device 2. When the toner in the developing device 2 is consumed by image formation, the toner concentration in the developing device 2 is detected by a T sensor (not shown), and a voltage having a value corresponding to the toner concentration is output. The control unit of the image forming apparatus stores a T target value for the output of the T sensor in advance. Based on the T target value and the output from the actual T sensor, the toner shortage in the developing device 2 is determined. Toner is replenished to compensate.

但し、画像濃度はトナー濃度のほか、トナー帯電量、温度や湿度の環境等によっても影響される。そこで、画像形成装置は、感光体１の所定位置にトナー付着量検出パターン（以下、Ｐパターンという）を形成するトナー付着量検出パターン形成手段と、トナー付着量検出パターンのトナー付着量を検出するトナー付着量検出手段とを備えている。トナー付着量検出手段としては、Ｐパターンの付着量を光学的に検出するＰセンサ８が用いられる。トナー付着量検出パターン形成手段は所定のタイミングで感光体１上にＰパターンを作成し、Ｐセンサ８は作成されたＰパターンを検出して、そのトナー付着量に応じた電圧を出力する。また、画像形成装置の制御部には、予めＰセンサの出力についてＰ目標値が格納されており、このＰ目標値と、実際のＰセンサからの出力とに基づき、画像濃度の濃淡を判断して、Ｔ目標値を適宜補正する。これにより、現像装置２内へのトナー補給が増減されてトナー濃度が調整されるので、安定した濃度の画像形成が可能となる。 However, the image density is influenced not only by the toner density but also by the toner charge amount, temperature and humidity environment, and the like. Therefore, the image forming apparatus detects a toner adhesion amount detection pattern forming unit that forms a toner adhesion amount detection pattern (hereinafter referred to as a P pattern) at a predetermined position of the photosensitive member 1 and a toner adhesion amount of the toner adhesion amount detection pattern. And a toner adhesion amount detecting means. As the toner adhesion amount detection means, a P sensor 8 that optically detects the adhesion amount of the P pattern is used. The toner adhesion amount detection pattern forming means creates a P pattern on the photoreceptor 1 at a predetermined timing, and the P sensor 8 detects the created P pattern and outputs a voltage corresponding to the toner adhesion amount. The control unit of the image forming apparatus stores a P target value for the output of the P sensor in advance, and determines the density of the image density based on the P target value and the output from the actual P sensor. Thus, the T target value is corrected as appropriate. As a result, toner supply to the developing device 2 is increased or decreased to adjust the toner density, so that an image with a stable density can be formed.

また、この画像形成装置においては、クリーニング装置７は、感光体１上より除去したトナーを現像装置２に戻し、再利用するための、トナーリサイクル機構を備えている。図２は、トナーリサイクル機構を説明するための斜視図である。クリーニング装置７は、クリーニングブレード６にて感光体１より除去されたトナーを回収するトナー回収羽根９と、トナー回収コイル１０とを備えている。トナー回収羽根９は、図中矢印方向へ回転することで、クリーニングブレード６にて感光体１より除去されたトナーを回収し、トナー回収コイル１０側へ搬送する。トナー回収コイル１０は、図中矢印方向へ回転しており、トナー回収羽根９により搬送された回収トナーを回収する。ここで、トナー回収コイル１０の周辺空間１０ａは、回収トナーを貯留するトナー貯留手段としての機能を有しており、クリーニングブレード６にて除去された回収トナーは、トナー回収羽根９を経て、トナー貯留手段であるトナー回収コイル１０の周辺空間１０ａに貯留される。トナー回収コイル１０の周辺空間１０ａでは、新たに回収されたトナーにより既に貯留されている回収トナーが押し出され、図中手前側へ徐々に移動する。図中手前側には、トナー回収コイル１０の周辺空間１０ａから現像装置２内に通じるトナー収容部１６へ連絡する回収トナー搬送路１５が設けられており、この回収トナー搬送路１５を介して、回収トナーが現像装置２内へ移動する。このようなトナーリサイクル機構により、感光体１上から除去された回収トナーが現像装置２に戻される。 In this image forming apparatus, the cleaning device 7 is provided with a toner recycling mechanism for returning the toner removed from the photoreceptor 1 to the developing device 2 for reuse. FIG. 2 is a perspective view for explaining the toner recycling mechanism. The cleaning device 7 includes a toner collection blade 9 that collects toner removed from the photoreceptor 1 by the cleaning blade 6 and a toner collection coil 10. The toner collection blade 9 rotates in the direction of the arrow in the drawing to collect the toner removed from the photoreceptor 1 by the cleaning blade 6 and convey it to the toner collection coil 10 side. The toner recovery coil 10 rotates in the direction of the arrow in the figure, and recovers the recovered toner conveyed by the toner recovery blade 9. Here, the peripheral space 10a of the toner recovery coil 10 has a function as a toner storage means for storing the recovered toner, and the recovered toner removed by the cleaning blade 6 passes through the toner recovery blade 9 and passes through the toner recovery blade 9. It is stored in the peripheral space 10a of the toner recovery coil 10 that is a storage means. In the peripheral space 10a of the toner collection coil 10, the collected toner already stored is pushed out by the newly collected toner and gradually moves to the front side in the figure. In the front side of the figure, there is provided a recovered toner conveyance path 15 that communicates from the peripheral space 10a of the toner recovery coil 10 to the toner accommodating portion 16 that communicates with the inside of the developing device 2, and through this recovered toner conveyance path 15, The collected toner moves into the developing device 2. The collected toner removed from the photoreceptor 1 is returned to the developing device 2 by such a toner recycling mechanism.

この画像形成装置において、着荷時または現像装置の交換時、初期現像剤による定着オフセットが発生してしまうことがある。定着オフセットを防止するためには、現像装置２内のトナー濃度を低下させることが有効であるが、画像を形成しない限りはトナー濃度を低下させることができない。そこで、この画像形成装置では、着荷時または現像装置の交換時、トナー濃度を低下させるために、感光体１上にトナー消費用パターンを作成し、これをクリーニングブレード６で除去回収することにより、強制的に現像装置２内のトナーを消費させる。この際、上記トナーリサイクル機構を採用していると、回収トナーが現像装置２に戻されてしまい、トナー濃度を効率的に低下させることができない。そこで、本実施形態の画像形成装置では、現像装置２が新品でないと判断された場合、回収トナーが回収トナー貯留手段に貯留され、一時的に現像装置２に戻らないような状態にして、強制的にトナーを消費させるようにする。 In this image forming apparatus, a fixing offset due to the initial developer may occur at the time of arrival or replacement of the developing device. In order to prevent the fixing offset, it is effective to reduce the toner density in the developing device 2, but the toner density cannot be reduced unless an image is formed. Therefore, in this image forming apparatus, a toner consumption pattern is created on the photosensitive member 1 in order to reduce the toner density upon arrival or replacement of the developing device, and this is removed and collected by the cleaning blade 6. The toner in the developing device 2 is forcibly consumed. At this time, if the toner recycling mechanism is employed, the collected toner is returned to the developing device 2, and the toner density cannot be reduced efficiently. Therefore, in the image forming apparatus according to the present embodiment, when it is determined that the developing device 2 is not new, the collected toner is stored in the collected toner storage unit and is not temporarily returned to the developing device 2 to be forced. The toner is consumed.

以下、図３に示す着荷時または現像装置の交換時における、画像形成に先立つ前処理動作のフローチャートに基づき、強制トナー消費動作について詳しく説明する。この画像形成装置は、現像装置２の新品検知手段（図示せず）を備えている。図３で、現像装置２の新品検知手段により現像装置２が新品でないと判断されると、前処理動作は行われず、画像形成動作の開始に向けて待機する。新品検知手段により現像装置２が新品と判断された場合は、以下の前処理動作が行われる。まず、現像剤充填回数カウントＸを０にする。ついで、帯電出力、帯電補正カウンタ、ＬＤ光量等がデフォルト値にリセットされる。また、メンテナンスキットカウウンタが０にリセットされる。次に、Ｐセンサ８が初期状態に設定される。ついで、新品の現像装置２の初期立ち上げのため、現像装置２内の現像剤攪拌動作が行われる。ついで、トナー濃度調整のため、トナーを強制的に消費させる強制トナー消費動作を実行する。強制トナー消費動作としては、感光体１上にトナー消費用パターンを作成し、そのトナー消費用パターンをクリーニングブレード６で感光体１表面から除去し、トナー回収羽根９およびトナー回収コイル１０により回収し、回収トナー貯留手段であるトナー回収コイル１０の周辺空間１０ａに貯留する。このとき、トナー回収コイル１０の周辺空間１０ａが空または空に近い状態であると、回収トナーは周辺空間１０ａに徐々に溜まっていくのみで、回収されたトナーが図中手前側へ徐々に移動し、回収トナー搬送路１５を介して現像装置２内へ移動することはない。一方、トナー回収コイル１０の周辺空間１０ａが既に回収トナーで充填された状態であると、新たに回収されたトナーにより既に貯留された回収トナーが押し出され、図中手前側へ移動し、回収トナー搬送路１５を介して現像装置２内へ戻ってしまう。そこで、現像装置２の新品への交換時、クリーニング装置７も同時に新品に交換して、トナー回収コイル１０の周辺空間１０ａを空の状態とすることで、トナー強制消費動作実行中に、トナー回収コイル１０の周辺空間１０ａに回収トナーを貯留することが可能となる。なお、本実施形態の画像形成装置では、上述のように、感光体１と、現像装置２と、帯電ローラ４と、クリーニング装置７とが一体的に支持されるように形成され、画像形成装置本体に脱着可能なプロセスカートリッジの形態をなしている。そこで、現像装置２の交換と、クリーニング装置７の交換とが同時に行え、上記トナー強制消費動作実行中に、回収トナーを現像装置２に戻すことなく、回収トナー貯留手段への貯留が簡単におこなえる。このような強制トナー消費動作の実行により、現像装置２内のトナー濃度を低下させ、トナー帯電量を上昇させる。この状態で画像形成をおこなうと、感光体１へのトナー付着量を低下させて転写紙上へのトナー付着量を低下させることができ、定着オフセットの防止が可能となる。この状態で、現像装置２内のトナー濃度をＴセンサ（図示せず）により検出し、検出結果に基づき、Ｔ目標値、Ｔセンサ出力上下限等の設定を行う。ついで、機械の立ち上げ動作を行い、画像形成動作の開始に向けて待機する。 Hereinafter, the forced toner consumption operation will be described in detail based on the flowchart of the preprocessing operation prior to image formation at the time of arrival or replacement of the developing device shown in FIG. This image forming apparatus includes a new article detecting means (not shown) of the developing device 2. In FIG. 3, when the developing device 2 determines that the developing device 2 is not new, the preprocessing operation is not performed and the apparatus waits for the start of the image forming operation. When the developing device 2 is determined to be new by the new product detection means, the following pre-processing operation is performed. First, the developer filling number count X is set to zero. Next, the charging output, the charging correction counter, the LD light quantity, etc. are reset to default values. In addition, the maintenance kit counter is reset to zero. Next, the P sensor 8 is set to an initial state. Next, a developer stirring operation in the developing device 2 is performed for the initial startup of the new developing device 2. Next, a forced toner consumption operation for forcibly consuming the toner is executed for toner density adjustment. In the forced toner consumption operation, a toner consumption pattern is created on the photosensitive member 1, the toner consumption pattern is removed from the surface of the photosensitive member 1 by the cleaning blade 6, and recovered by the toner recovery blade 9 and the toner recovery coil 10. The toner is stored in the peripheral space 10a of the toner recovery coil 10 which is a recovery toner storage means. At this time, if the peripheral space 10a of the toner recovery coil 10 is empty or nearly empty, the recovered toner only accumulates gradually in the peripheral space 10a, and the recovered toner gradually moves toward the front in the figure. However, it does not move into the developing device 2 via the collected toner conveyance path 15. On the other hand, if the peripheral space 10a of the toner collection coil 10 is already filled with the collected toner, the collected toner already stored is pushed out by the newly collected toner and moves to the near side in the figure, and is collected. It returns to the inside of the developing device 2 through the conveyance path 15. Therefore, when the developing device 2 is replaced with a new one, the cleaning device 7 is also replaced with a new one at the same time, and the peripheral space 10a of the toner collecting coil 10 is emptied so that the toner collecting operation can be performed during the forced toner consumption operation. The collected toner can be stored in the peripheral space 10a of the coil 10. In the image forming apparatus according to the present embodiment, as described above, the photosensitive member 1, the developing device 2, the charging roller 4, and the cleaning device 7 are formed so as to be integrally supported. It is in the form of a process cartridge that is removable from the main body. Therefore, the developing device 2 and the cleaning device 7 can be replaced at the same time, and the collected toner can be easily stored in the collected toner storage means without returning the collected toner to the developing device 2 during execution of the forced toner consumption operation. . By executing such a forced toner consumption operation, the toner density in the developing device 2 is decreased and the toner charge amount is increased. When image formation is performed in this state, the toner adhesion amount on the photosensitive member 1 can be reduced to reduce the toner adhesion amount on the transfer paper, and fixing offset can be prevented. In this state, the toner density in the developing device 2 is detected by a T sensor (not shown), and the T target value, the T sensor output upper and lower limits, etc. are set based on the detection result. Next, the machine starts up and waits for the start of the image forming operation.

図３のフローチャートに基づき、初期現像剤のトナー濃度のデフォルトが４［ｗｔ％］である実機を用い、トナー濃度が３［ｗｔ％］となるように狙い、強制トナー消費動作を行った。このような強制トナー消費動作を実行した場合と、強制トナー消費動作を実行しなかった場合との、トナー濃度、トナー帯電量および定着オフセット部分のＩＤ、定着オフセットのレベルを評価した結果を表１に示す。なお、定着オフセット部分のＩＤとは、ハーフトーン縦帯画像における定着オフセット発生位置のＩＤであり、ＩＤが高いほど定着オフセットレベルが悪く、ＩＤが低いほど定着オフセットレベルが良いということになる。

表１の結果より、図３のフローチャートに基づく強制トナー消費動作の実行により、初期現像剤のトナー濃度が下がり、トナー帯電量が上昇して定着オフセットが改善していることがわかる。 Based on the flowchart of FIG. 3, forcible toner consumption operation was performed using an actual machine whose initial developer has a toner concentration default of 4 wt% and aimed at a toner concentration of 3 wt%. Table 1 shows the results of evaluating the toner density, the toner charge amount, the ID of the fixing offset portion, and the fixing offset level when the forced toner consumption operation is executed and when the forced toner consumption operation is not executed. Shown in The ID of the fixing offset portion is the ID of the fixing offset occurrence position in the halftone vertical band image. The higher the ID, the worse the fixing offset level, and the lower the ID, the better the fixing offset level.

From the results in Table 1, it can be seen that the execution of the forced toner consumption operation based on the flowchart of FIG. 3 decreases the toner concentration of the initial developer, increases the toner charge amount, and improves the fixing offset.

さらに、図３のフローチャートに基づく強制トナー消費動作を実行する際、より確実に回収トナーが回収トナー貯留手段から現像装置２に戻らないようにするために、回収トナー搬送路１５中に開閉可能なシャッター部材（図示せず）を設けてもよい。強制トナー消費動作を行っている時は、シャッター部材を閉じた状態とし、回収トナー搬送路１５を通って介して回収トナーが現像装置２に戻らないようにする。また、強制トナー消費動作を実行していない時は、シャッター部材は常に開いた状態とし、回収トナーを現像装置２に戻すことでトナーリサイクルがおこなわれるようにする。 Further, when the forced toner consumption operation based on the flowchart of FIG. 3 is executed, the toner can be opened and closed in the collected toner conveyance path 15 in order to prevent the collected toner from returning from the collected toner storing means to the developing device 2 more reliably. A shutter member (not shown) may be provided. When the forced toner consumption operation is performed, the shutter member is closed so that the collected toner does not return to the developing device 2 through the collected toner conveyance path 15. Further, when the forced toner consumption operation is not executed, the shutter member is always opened, and the toner is recycled by returning the collected toner to the developing device 2.

次に、画像形成に先立つ前処理動作の変形例について説明する。
上述のように、画像形成の為の前処理動作中に強制トナー消費動作を行うと、トナー付着量が低下することで画像濃度が低下する可能性がある。ユーザーによっては、定着オフセットの未発生より、常に画像濃度の低下の未発生を優先に考える場合もある。そこで、ユーザーのニーズに合わせて、ユーザー本人、もしくは、サービスマンが、強制トナー消費動作をおこなうか否かを選択する手段を設けることもできる。図４は、前処理動作のフローチャートの変形例である。図４のフローチャートでは、図３のフローチャートで、強制トナー消費動作の実行の前に、外部信号入力手段により初期現像剤の強制トナー消費動作実行の可否を選択するものである。外部信号入力手段としては、例えば、画像形成装置に付随した操作パネルを操作する手段や画像形成装置のパソコンを接続して情報を入力する手段などがあげられる。 Next, a modified example of the preprocessing operation prior to image formation will be described.
As described above, if the forced toner consumption operation is performed during the pre-processing operation for image formation, there is a possibility that the image density is lowered due to a decrease in the toner adhesion amount. Some users may always prioritize the absence of a decrease in image density over the occurrence of a fixing offset. Therefore, it is possible to provide a means for the user himself / herself or a serviceman to select whether or not to perform the forced toner consumption operation according to the user's needs. FIG. 4 is a modification of the flowchart of the preprocessing operation. In the flowchart of FIG. 4, whether or not to execute the forced toner consumption operation of the initial developer is selected by the external signal input unit before the forced toner consumption operation is performed. Examples of the external signal input means include means for operating an operation panel attached to the image forming apparatus and means for inputting information by connecting a personal computer of the image forming apparatus.

また、着荷時または現像装置の交換時であっても、放置時間によってはトナー帯電量の低下が小さく、定着オフセットが発生しない場合がある。具体的には、初期現像剤が製造されて間もない場合は、トナーの放置放電量が少ないため、定着オフセットは発生しない。このような場合に、上記強制トナー消費動作を実行すると、かえってトナー帯電量が上がり過ぎてしまい、画像濃度が低下する副作用が発生する場合がある。そこで、図５のフローチャートに示すように、初期現像剤使用年月日と初期現像剤製造年月日から初期現像剤の放置時間を認識し、放置時間が一定期間を超えた場合にだけ、強制トナー消費動作を実行するようにしてもよい。初期現像剤製造年月日は、ユーザー本人、もしくは、サービスマンが、初期現像剤の製造コードを外部入力手段によって入力し、これに基づき認識することができる。また、現像装置２が、製造年月日の情報を有するＩＣチップ備えている場合には、画像形成装置がＩＣチップの情報を読取り初期現像剤の製造年月日を認識する。初期現像剤使用年月日は、画像形成装置の機能として含まれているタイマーで認識する。そして、(初期現像剤使用年月日)-(初期現像剤製造年月日)のＹが一定期間を超えている場合にのみ、強制トナー消費動作を実行する。本実施形態では、Ｙ＝３０とし、放置時間が３０日を越える場合に強制トナー消費動作を実行したが、Ｙは初期現像剤の特性や初期現像剤の放置環境によって決定されるものであり、これに限らずその諸特性に応じて適宜、効果が得られるよう変更する。 Further, even when it arrives or when the developing device is replaced, depending on the standing time, the decrease in the toner charge amount may be small and fixing offset may not occur. Specifically, when the initial developer is just manufactured, the amount of neglected discharge of the toner is small, so that no fixing offset occurs. In such a case, if the forced toner consumption operation is executed, the toner charge amount may increase excessively, which may cause a side effect of reducing the image density. Therefore, as shown in the flowchart of FIG. 5, the initial developer use time is recognized from the initial developer use date and the initial developer manufacture date, and only when the left time exceeds a certain period, it is compulsory. A toner consumption operation may be executed. The initial developer manufacturing date can be recognized based on the user or the serviceman who inputs the manufacturing code of the initial developer by the external input means. When the developing device 2 includes an IC chip having information on the date of manufacture, the image forming apparatus reads the information on the IC chip and recognizes the date of manufacture of the initial developer. The initial developer use date is recognized by a timer included as a function of the image forming apparatus. The forced toner consumption operation is executed only when Y in (initial developer use date) − (initial developer manufacture date) exceeds a certain period. In this embodiment, the forced toner consumption operation is executed when Y = 30 and the leaving time exceeds 30 days. However, Y is determined by the characteristics of the initial developer and the leaving environment of the initial developer. Not only this but it changes suitably according to the various characteristics so that an effect may be acquired.

また、着荷時または現像装置の交換時であっても、上記放置時間以外でも放置環境によっては、トナー帯電量の低下が小さく、トナー付着量が過多にならずに定着オフセットが発生しない場合がある。そこで、図６のフローチャートに示すように、強制トナー消費動作の実行の前に感光体１上のトナー付着量を検出し、これに基づき強制トナー消費動作を実行の用不要を決定するようにしてもよい。なお、図６のフローチャートは、図３のフローチャートにおいて、現像剤攪拌動作以降の部分でＰセンサ８によるトナー付着量を検出結果に基づく強制トナー消費動作を実行をの用不要を説明したものであり、前処理動作については省略している。 Also, even at the time of arrival or replacement of the developing device, depending on the leaving environment other than the above-mentioned leaving time, there is a case where the decrease in the toner charge amount is small and the toner adhesion amount is not excessive and the fixing offset does not occur. . Therefore, as shown in the flowchart of FIG. 6, the toner adhesion amount on the photosensitive member 1 is detected before the forced toner consumption operation is executed, and it is determined based on this whether or not the forced toner consumption operation is required. Also good. The flowchart in FIG. 6 explains the necessity of executing the forced toner consumption operation based on the detection result of the toner adhesion amount by the P sensor 8 in the portion after the developer stirring operation in the flowchart in FIG. The preprocessing operation is omitted.

具体的には、図６のフローチャートに示すように、強制トナー消費動作を実行の前に、上記トナー付着量検出パターン形成手段によりＰパターンを作成し、Ｐセンサ８によりＰパターンのトナー付着量を検出する。そして、トナー付着量の検出結果が、予め決められたトナー付着量が最適値であるＰ目標値となっているかの判断して、トナー付着量が最適となっていた場合には、強制トナー消費動作は行なわず、次のＴセンサ出力読み取り動作を行う。トナー付着量が過多であり、トナー付着量の検出結果がＰ目標値と異なっている場合は、強制トナー消費動作をおこない、トナー濃度を下げ、トナー帯電性を上げて、トナー付着量を低下させる。さらに、トナー消費動作終了後に、再度、Ｐパターンを作成し、Ｐセンサ８によりＰパターンのトナー付着量を検出する。そして、トナー付着量の検出結果が、予め決められたトナー付着量が最適値であるＰ目標値となっているかの判断する。トナー付着量が最適となっていた場合には、強制トナー消費動作は終了し、次のＴセンサ出力読み取り動作を行う。また、トナー付着量が過多であり、トナー付着量の検出結果がＰ目標値と異なっている場合は、再度、強制トナー消費動作をおこなう。このようなＰセンサ８によるトナー付着量を検出、最適値であるかどうかの判断、強制トナー消費動作の実行という一連の動作を交互にトナー付着量が最適値となるまで繰り返しおこなう。 Specifically, as shown in the flowchart of FIG. 6, before executing the forced toner consumption operation, a P pattern is created by the toner adhesion amount detection pattern forming means, and the P sensor 8 determines the toner adhesion amount of the P pattern. To detect. Then, it is judged whether the toner adhesion amount detection result is a P target value that is a predetermined toner adhesion amount, and if the toner adhesion amount is optimum, forced toner consumption The next T sensor output reading operation is performed without performing the operation. When the toner adhesion amount is excessive and the detection result of the toner adhesion amount is different from the P target value, the forced toner consumption operation is performed, the toner density is lowered, the toner charging property is raised, and the toner adhesion amount is lowered. . Further, after completion of the toner consumption operation, a P pattern is created again, and the P sensor 8 detects the toner adhesion amount of the P pattern. Then, it is determined whether the detection result of the toner adhesion amount is a P target value that is a predetermined value of the toner adhesion amount. If the toner adhesion amount is optimum, the forced toner consumption operation is terminated, and the next T sensor output reading operation is performed. Further, when the toner adhesion amount is excessive and the detection result of the toner adhesion amount is different from the P target value, the forced toner consumption operation is performed again. Such a series of operations of detecting the toner adhesion amount by the P sensor 8, determining whether or not it is the optimum value, and executing the forced toner consumption operation are alternately repeated until the toner adhesion amount becomes the optimum value.

なお、このようなＰセンサ８によるトナー付着量を検出、最適値であるかどうかの判断、強制トナー消費動作の実行という一連の動作をトナー付着量が最適値となるまで繰り返しおこなうものを、図４、５に示す画像形成に先立つ前処理動作のフローチャートに組み込んでもよい。すなわち、外部信号入力手段により初期現像剤の強制トナー消費動作実行の可否の選択の前、もしくは、後、または、初期現像剤の放置時間による強制トナー消費動作を実行の前、もしくは、後に、Ｐセンサ８によりトナー付着量を検出し最適値であるかどうかの判断をして、強制トナー消費動作の実行の用不要を決めてもよい。 A series of operations such as detecting the toner adhesion amount by the P sensor 8, determining whether or not it is the optimum value, and executing the forced toner consumption operation are repeated until the toner adhesion amount reaches the optimum value. It may be incorporated in the flowchart of the preprocessing operation prior to image formation shown in FIGS. That is, before or after the selection of whether or not to execute the forced toner consumption operation of the initial developer by the external signal input means, or before or after the execution of the forced toner consumption operation based on the initial developer leaving time, It may be determined whether or not it is necessary to execute the forced toner consumption operation by detecting the toner adhesion amount by the sensor 8 and determining whether or not the toner adhesion amount is an optimum value.

いずれの場合も、Ｐセンサ８によるトナー付着量の検出結果に基づき強制トナー消費動作の実行の用不要を決めるものでは、実際のトナー付着量に基づいたトナー濃度の調整が行えるので、放置時間、放置環境に差があっても、より効果的に定着オフセットを防止することができる。また、Ｐセンサ８によるトナー付着量の検出結果に基づき強制トナー消費動作の実行の終了を決めるので、トナー帯電量が上昇しすぎて画像濃度が低下してしまうという副作用も効果的に防止することができる。 In any case, in the case where the necessity of executing the forced toner consumption operation is determined based on the detection result of the toner adhesion amount by the P sensor 8, the toner density can be adjusted based on the actual toner adhesion amount. Even if there is a difference in the leaving environment, fixing offset can be more effectively prevented. Further, since the end of execution of the forced toner consumption operation is determined based on the detection result of the toner adhesion amount by the P sensor 8, it is possible to effectively prevent the side effect that the toner charge amount increases too much and the image density decreases. Can do.

次に、Ｐセンサ８によるトナー付着量の検出結果に基づき強制トナー消費動作の実行の用不要を決めるもの変形例について説明する。図７は、Ｐセンサ８によるトナー付着量の検出結果に基づき強制トナー消費動作の実行の用不要を決める前処理動作の変形例のフローチャートである。図７のフローチャートでは、Ｐセンサ８によって検出されるＰパターンの検出値（Ｖｓｐ）とＰパターン以外のトナー付着が無い部分の感光体１の検出値（Ｖｓｇ）の比率Ｖｓｐ／Ｖｓｇにより、強制トナー消費動作の実行の用不要を判断するものである。本実施例では、Ｖｓｐ／Ｖｓｇが０．１２以上となったとき強制トナー消費動作が終了とする。 Next, a description will be given of a modification in which the necessity of executing the forced toner consumption operation is determined based on the detection result of the toner adhesion amount by the P sensor 8. FIG. 7 is a flowchart of a modified example of the pre-processing operation for determining whether or not to execute the forced toner consumption operation based on the detection result of the toner adhesion amount by the P sensor 8. In the flowchart of FIG. 7, forced toner is calculated based on a ratio Vsp / Vsg between the detection value (Vsp) of the P pattern detected by the P sensor 8 and the detection value (Vsg) of the photosensitive member 1 in the portion other than the P pattern where no toner adheres. This is to determine whether or not it is necessary to execute the consumption operation. In this embodiment, the forced toner consumption operation is terminated when Vsp / Vsg is 0.12 or more.

以下、本実施例での強制トナー消費動作実行可否の閾値（Ｖｓｐ／Ｖｓｇ）決定の経緯について説明する。図８は、Ｖｓｐ／Ｖｓｇ値と定着オフセットランクの関係を示したグラフである。定着オフセットに関しては、両面画像形成時の両面第一面のハーフトーン部のオフセット、両面第二面のハーフトーン部のオフセット、および、最もオフセットの発生が顕著である罫線画像部のオフセットの３水準で評価している。定着オフセットの顕在化を防止するには、この３水準のオフセットともランク４以上でなければならない。また、図９は、Ｖｓｐ／Ｖｓｇ値と画像濃度（ベタ濃度ＩＤ）との関係を示したものである。定着オフセットの発生が無い場合でも、付着量が下がりすぎて過度のＩＤ低下が発生してはならない。ここでＩＤの保証値を１．２以上とする。このような観点から、図８で定着オフセットの顕在化を防止するために３水準のオフセットともランク４以上とし、且つ、図９で過度のＩＤ低下が発生しないようにするために、閾値をＶｓｐ／Ｖｓｇを０．１２とする。すなわち、Ｖｓｐ／Ｖｓｇ値が０．１２以上となった場合、強制トナー消費動作の実行を終了することにした。但し、現像剤特性や定着ユニットのマージンなど画像形成装置によって条件が異なるので、閾値に余裕を持たせ、Ｖｓｐ／Ｖｓｇ値で０．１２±０．５の間で可変することが好ましい。 Hereinafter, the process of determining the threshold value (Vsp / Vsg) for determining whether or not to execute the forced toner consumption operation in this embodiment will be described. FIG. 8 is a graph showing the relationship between the Vsp / Vsg value and the fixing offset rank. Regarding the fixing offset, there are three levels: the offset of the halftone portion on the first side of the double-sided image, the offset of the halftone portion of the second side of the double-sided image, and the offset of the ruled line image portion where the occurrence of the offset is most noticeable. It is evaluated with. In order to prevent the fixing offset from becoming obvious, all of the three levels of offsets must be rank 4 or higher. FIG. 9 shows the relationship between the Vsp / Vsg value and the image density (solid density ID). Even if there is no occurrence of fixing offset, the amount of adhesion should not be too low and excessive ID reduction should not occur. Here, the guaranteed ID value is 1.2 or more. From this point of view, in order to prevent the fixing offset from becoming obvious in FIG. 8, the three-level offset is set to rank 4 or higher, and in order to prevent excessive ID reduction in FIG. / Vsg is set to 0.12. That is, when the Vsp / Vsg value is 0.12 or more, the forced toner consumption operation is terminated. However, since conditions vary depending on the image forming apparatus such as developer characteristics and fixing unit margin, it is preferable to allow a threshold value and vary the Vsp / Vsg value between 0.12 ± 0.5.

上記強制トナー消費動作の実行において、例えば、Ｐセンサ不良があり、Ｖｓｐ／Ｖｓｇ値を正確に検出できなかった場合、強制トナー消費動作を強制終了させる動作がないと、トナー消費動作を際限なく繰り返してしまうという不具合が発生する可能性がある。そこで、本実施例の画像形成装置では、強制トナー消費動作を強制終了させるモードを設け、上記問題の発生を防ぐリミッターの役割を呈するようにする。図１０は、強制トナー消費動作を強制終了させるモードを設けた前処理動作のフローチャートである。図１０のフローチャートでは、強制トナー消費動作の実行回数Ｙが１６回を超えたときに、強制トナー消費動作の実行を強制終了する。しかしながら、１回のトナー消費動作で消費するトナー量、現像剤特性、機械特性等は装置により異なるので、この値は可変とする。 In the execution of the forced toner consumption operation, for example, if there is a P sensor failure and the Vsp / Vsg value cannot be detected accurately, the toner consumption operation is repeated indefinitely if there is no operation to forcibly terminate the forced toner consumption operation. There is a possibility that a problem will occur. Therefore, in the image forming apparatus of this embodiment, a mode for forcibly terminating the forced toner consumption operation is provided to serve as a limiter for preventing the occurrence of the above problem. FIG. 10 is a flowchart of the preprocessing operation provided with a mode for forcibly terminating the forced toner consumption operation. In the flowchart of FIG. 10, the execution of the forced toner consumption operation is forcibly terminated when the number Y of executions of the forced toner consumption operation exceeds 16. However, since the amount of toner consumed in one toner consumption operation, developer characteristics, mechanical characteristics, and the like differ depending on the apparatus, this value is variable.

以下、本実施例でのトナー消費モード最大実行回数(１６回)決定の経緯について説明する。本実施例では、１回の強制トナー消費動作で、画像面積が６６５［ｃｍ^２］のフルドットのベタ画像を感光体１上に形成し、それをクリーニング装置７で回収することで初期現像剤のトナーを強制的に消費している。すなわち、強制トナー消費動作を１６回行なった場合は、６６５［ｃｍ^２］× １６＝１０６４０［ｃｍ^２］の画像面積のフルドットベタ画像分のトナーを消費することになる。図１１に、強制トナー消費モードの実行回数を１４回、１５回、１６回、１７回、１８回としたときの画像のベタ濃度ＩＤを示す。なお、強制トナー消費動作のそれぞれの実行回数での消費パターンの画像面積は、表２に示す通りである。

図１１より、強制トナー消費動作を１４回、１５回とした場合は、定着オフセットが発生する可能性があり、定着オフセットの抑止効果が弱いことがわかる。また、強制トナー消費動作を１７回、１８回とした場合は、ベタ濃度ＩＤが保証値の１．２を下回る可能性があることがわかった。そこで、本実施例では,トナー消費モードの最大実行回数を１６回と決定した。 The process of determining the maximum toner consumption mode execution count (16 times) in this embodiment will be described below. In this embodiment, a solid dot full image having an image area of 665 [cm ² ] is formed on the photosensitive member 1 by one forced toner consumption operation, and the initial developer is collected by the cleaning device 7. The toner is forcibly consumed. That is, when the forced toner consumption operation is performed 16 times, the toner of the full dot solid image having the image area of 665 [cm ² ] × 16 = 10640 [cm ² ] is consumed. FIG. 11 shows solid density IDs of images when the number of executions of the forced toner consumption mode is 14, 15, 16, 17, and 18. Note that the image area of the consumption pattern at each execution number of the forced toner consumption operation is as shown in Table 2.

From FIG. 11, it can be seen that when the forced toner consumption operation is 14 times or 15 times, a fixing offset may occur and the effect of suppressing the fixing offset is weak. Further, it was found that when the forced toner consumption operation is 17 times or 18 times, the solid density ID may be lower than the guaranteed value 1.2. Therefore, in this embodiment, the maximum number of executions of the toner consumption mode is determined to be 16 times.

次に、トナー消費用パターン画像について説明する。強制トナー消費動作では、感光体１にトナー消費用パターン画像を形成し、それをクリーニングブレード６によりクリーニングして、クリーニング装置７の回収トナー貯留手段に貯留する。一般的にクリーニングブレード６は、画像形成時の転写残トナーをクリーニングする機能は備えているが、トナー消費用パターン画像のような実画像をクリーニングしようとすると、トナー量が多くなって負荷が大きくなり、クリーニング不良やクリーニングブレード６からのトナーのすり抜けが発生しやすくなる。特に、本実施形態のように帯電装置として感光体１に接触する帯電ローラ４を用いた場合は、これらのクリーニングしきれなかったトナーが帯電ローラ４を汚してしまい、これに起因する異常画像が発生することがある。そこで、図１２(ａ)、（ｂ）、（ｃ）のようなトナー消費用パターンを作成し、強制トナー消費動作を行い、その際のクリーニングブレード６の負荷について検討する実験をおこなった。 Next, the toner consumption pattern image will be described. In the forced toner consumption operation, a pattern image for toner consumption is formed on the photoreceptor 1, cleaned by the cleaning blade 6, and stored in the collected toner storage unit of the cleaning device 7. In general, the cleaning blade 6 has a function of cleaning the transfer residual toner at the time of image formation. However, when an actual image such as a pattern image for toner consumption is to be cleaned, the amount of toner increases and the load becomes large. Accordingly, defective cleaning and toner slipping from the cleaning blade 6 are likely to occur. In particular, when the charging roller 4 in contact with the photosensitive member 1 is used as a charging device as in the present embodiment, the toner that could not be cleaned completely contaminates the charging roller 4, and an abnormal image due to the toner is generated. May occur. Therefore, an experiment was conducted to create a toner consumption pattern as shown in FIGS. 12A, 12B, and 12C, perform a forced toner consumption operation, and examine the load of the cleaning blade 6 at that time.

図１２(ａ)、（ｂ）、（ｃ）のトナー消費用パターンの画像面積は全て同じである。図１２(ａ)のパターン画像は、全面ベタの画像である。図１２(ａ)のパターン場合、トナー回収時にクリーニングブレード６への負荷が大きく、クリーニング不良やトナーのすり抜けが発生し、帯電ローラ４表面の汚れもひどくなり帯電ローラ汚れに伴う帯電ローラピッチの異常画像が発生した。図１２（ｂ）のパターンは、主走査方向に長く、副走査方向に短い長方形の画像であり、ベタ画像の間に、副走査方向長さと同じ長さの間隔を設けたものである。図１２(ｂ)のパターン場合、図１２(ａ)のパターンに比べるとクリーニングブレード６への負荷が小さく、クリーニング不良やトナーのすり抜けは少なく、若干、帯電ローラ４表面の汚れはあるものの、異常画像は発生しなかった。図１２（ｃ）のパターンは、主走査方向に長く、副走査方向に短い長方形の画像であり、ベタ画像の間に、副走査方向長さの２倍の長さの間隔を設けたものである。図１２(ｃ)のパターン場合、図１２(ｂ)のパターンよりさらにクリーニングブレード６への負荷が小さく、帯電ローラ４表面は汚れず,異常画像も発生しなかった。この実験の結果から、感光体１上に形成するトナー消費用パターン画像は、主走査方向へ長く、副走査方向に短い長方形を、副走査方向に対して間隔を設けて形成していくことで、クリーニングブレード６への負荷が小さくなり、クリーニング不良やクリーニングブレードからのトナーのすり抜けの発生を防止することができる。また、感光体１へ形成するトナー消費用パターン内のトナー像の間隔が広いほど、クリーニング不良やクリーニングブレードからのトナーのすり抜けに対しては有利であることがわかった。しかし、感光体１上へ形成するトナー像の間隔が広いほど、初期現像剤のトナー消費にかかる時間が多くなってしまう。そこで、初期現像剤やクリーニング装置７の特性によって、クリーニング不良やトナーのすり抜けが発生せず、且つ、なるべく短い時間で初期現像剤のトナーを消費できるようなトナー像間の間隔を適宜設けることが望ましい。 The image areas of the toner consumption patterns in FIGS. 12A, 12B, and 12C are all the same. The pattern image in FIG. 12A is a solid image. In the case of the pattern shown in FIG. 12A, the load on the cleaning blade 6 is large at the time of toner recovery, cleaning failure and toner slipping occur, the surface of the charging roller 4 becomes very dirty, and the charging roller pitch is abnormal due to the charging roller contamination. An image has occurred. The pattern in FIG. 12B is a rectangular image that is long in the main scanning direction and short in the sub-scanning direction, and has an interval of the same length as the length in the sub-scanning direction between the solid images. In the case of the pattern of FIG. 12B, the load on the cleaning blade 6 is smaller than that of the pattern of FIG. 12A, cleaning defects and toner slipping are few, and the surface of the charging roller 4 is slightly stained but abnormal. No image was generated. The pattern in FIG. 12C is a rectangular image that is long in the main scanning direction and short in the sub-scanning direction, and has an interval that is twice as long as the length in the sub-scanning direction between the solid images. is there. In the case of the pattern of FIG. 12C, the load on the cleaning blade 6 was further smaller than that of the pattern of FIG. 12B, the surface of the charging roller 4 was not soiled, and no abnormal image was generated. As a result of this experiment, the toner consumption pattern image formed on the photosensitive member 1 is formed by forming a rectangle that is long in the main scanning direction and short in the sub scanning direction with an interval in the sub scanning direction. Thus, the load on the cleaning blade 6 is reduced, and it is possible to prevent the occurrence of poor cleaning and toner slip-through from the cleaning blade. Further, it was found that the wider the interval between the toner images in the toner consumption pattern formed on the photosensitive member 1, the more advantageous for cleaning failure and toner slipping from the cleaning blade. However, as the interval between the toner images formed on the photosensitive member 1 increases, the time required for the toner consumption of the initial developer increases. Therefore, depending on the characteristics of the initial developer and the cleaning device 7, an interval between toner images may be appropriately provided so that cleaning failure and toner slip-through do not occur and the toner of the initial developer can be consumed in as short a time as possible. desirable.

ところで、画像形成装置では、転写位置にて感光体１に密着した転写紙を感光体１から分離する分離手段として、図１に示すように、転写位置よりも下流の感光体１に接触するよう分離爪１１を設ける場合がある。この場合、例えば、図１２(ａ)、（ｂ）、（ｃ）に示すような、主走査方向の全幅に渡るようなトナー消費用パターンを感光体１上へ作成し、転写されることなく実画像としてそのままクリーニングブレード６まで移動する間に、分離爪１１をトナーで汚してしまうことがある。このような分離爪１１のトナー汚れにより、異常画像が発生することがある。そこで、トナー消費用パターンとしては、図１３に示すように、分離爪１１の配置された部分を避けるように、主走査方向に複数に分割されたトナー消費用パターンを用いることが好ましい。このようなトナー消費用パターンを用いることで、トナーで分離爪を汚してしまう虞がなくなり、これに伴う異常画像の発生を防止できる。 By the way, in the image forming apparatus, as shown in FIG. 1, as a separating means for separating the transfer paper that is in close contact with the photosensitive member 1 at the transfer position, it contacts the photosensitive member 1 downstream of the transfer position. A separation claw 11 may be provided. In this case, for example, a toner consumption pattern that covers the entire width in the main scanning direction as shown in FIGS. 12A, 12B, and 12C is formed on the photosensitive member 1 without being transferred. While moving to the cleaning blade 6 as it is as an actual image, the separation claw 11 may be soiled with toner. An abnormal image may occur due to the toner contamination of the separation claw 11. Therefore, as the toner consumption pattern, as shown in FIG. 13, it is preferable to use a toner consumption pattern divided into a plurality of parts in the main scanning direction so as to avoid the portion where the separation claw 11 is arranged. By using such a toner consumption pattern, there is no possibility that the separation claw is stained with toner, and the occurrence of abnormal images associated therewith can be prevented.

また、本実施形態の画像形成装置では、上述のように、感光体１と、現像装置２と、帯電ローラ４と、クリーニング装置６とが一体的に支持されるように形成され、画像形成装置本体に脱着可能なプロセスカートリッジの形態をなしている。このようなプロセスカートリッジの形態をとることで、現像装置２の交換と、クリーニング装置６の交換とが同時に行え、上記トナー強制消費動作実行中に、回収トナーを現像装置２に戻すことなく、回収トナー貯留手段への貯留が簡単におこなえる。また、メンテナンスを容易に行うことができるというメリットがある。 In the image forming apparatus according to the present embodiment, as described above, the photosensitive member 1, the developing device 2, the charging roller 4, and the cleaning device 6 are formed so as to be integrally supported. It is in the form of a process cartridge that is removable from the main body. By adopting such a process cartridge, the developing device 2 and the cleaning device 6 can be replaced at the same time, and the collected toner is not returned to the developing device 2 during the forced toner consumption operation. Storage in the toner storage means can be easily performed. Further, there is an advantage that maintenance can be easily performed.

以上、本実施形態によれば、新品検知手段により現像装置２が新品と検知された場合に、感光体１上に所定のトナー消費用パターンを作像し、これをクリーニングブレード６により回収して、回収トナーを回収トナー貯留手段に貯留させた状態で、現像装置２内のトナーを強制的に消費させる強制トナー消費動作を実行する。このように一時的に回収トナーを現像装置２に戻さないようにした状態で、強制トナー消費動作を実行することで、現像装置２内のトナー濃度を下げることが可能となる。よって、初期現像剤のトナー帯電量を上昇させ、感光体１へのトナー付着量を抑え、記録媒体上のトナー付着量を下げることができる。これにより、トナーリサイクルをおこなう画像形成装置においても、初期現像剤による定着オフセットを防止することができる。
また、強制トナー消費動作の実行の可否を外部より選択できる選択手段を設け、強制トナー消費動作を実行する前に選択手段の選択結果に基づき強制トナー消費動作の実行の要不要を判断し、判断結果に基づき強制トナー消費動作を実行する。これは、強制トナー消費動作を行うと、トナー付着量が低下することで画像濃度が低下する場合があり、ユーザーによっては、定着オフセットの未発生より、常に画像濃度の低下の未発生を優先に考える場合もある。このようなユーザーのニーズに対応するために、選択手段の選択結果に基づき強制トナー消費動作を実行するものである。
また、現像装置２の交換時に収容される現像剤の製造年月日を識別できる情報を外部より入力する現像剤情報入力手段を設け、強制トナー消費動作を実行する前に現像剤情報入力手段により入力された情報に基づき現像剤の製造年月日を識別して強制トナー消費動作の実行の要不要を判断し、判断結果に基づき該強制トナー消費動作を実行する。また、現像装置２が収容される現像剤の製造年月日を識別できる現像剤情報識別部材を有しており、強制トナー消費動作を実行する前に現像剤情報識別部材より現像剤の製造年月日を識別して強制トナー消費動作の実行の要不要を判断し、判断結果に基づき強制トナー消費動作を実行する。これらは、現像装置２が新品であっても、放置時間が短い場合はトナー帯電量の低下が小さく、定着オフセットが発生しない場合がある。このような場合に、上記強制トナー消費動作を実行すると、かえってトナー帯電量が上がり過ぎてしまい、画像濃度が低下するという副作用が発生する場合がある。このような、初期現像剤の放置時間が短い場合に対応するものである。
また、強制トナー消費動作の実行中に、現像装置２により感光体１にＰパターンを形成し、Ｐセンサ８によりＰパターンのトナー付着量の検出を行い、検出結果が所定の目標値となった場合に強制トナー消費動作の実行を終了する。これは、現像装置２が新品でも、上記放置時間以外でも放置環境によっては、トナー帯電量の低下が小さく、トナー付着量が過多にならずに定着オフセットが発生しない場合がある。そこで、強制トナー消費動作の実行の前に感光体１上のトナー付着量を検出し、これに基づき強制トナー消費動作を実行の用不要を決定する。このように、Ｐセンサ８によるトナー付着量の検出結果に基づき強制トナー消費動作の実行の用不要を決めるものでは、実際のトナー付着量に基づいたトナー濃度の調整が行えるので、放置時間、放置環境に差があっても、より効果的に定着オフセットを防止することができる。また、Ｐセンサ８によるトナー付着量の検出結果に基づき強制トナー消費動作の実行の終了を決めるので、トナー帯電量が上昇しすぎて画像濃度が低下するという副作用も効果的に防止することができる。
また、強制トナー消費動作の実行の終了を判断するためにおこなうＰパターンの作成およびＰセンサによるトナー付着量の検出と、強制トナー消費動作の実行とを、交互におこなう。また、強制トナー消費動作の実行の終了を判断するためにおこなうＰパターンの作成およびＰセンサによるトナー付着量の検出と、強制トナー消費動作の実行とを、複数回おこなう。これらにより、強制トナー消費動作の実行および終了を的確に判断することができ、効果的な定着オフセットの防止、および、画像濃度が低下の防止が行える。
また、Ｐセンサ８はＰパターンのパターン部検出値（Ｖｓｐ）と地肌部検出値（Ｖｓｇ）とを検出し、これらの比率（Ｖｓｐ／Ｖｓｇ）が所定の値以上となったとき、検出結果が所定の目標値となったと判断する。このように、パターン部検出値（Ｖｓｐ）と地肌部検出値（Ｖｓｇ）とを用いているので、強制トナー消費動作の実行および終了の的確な判断ができ、効果的な定着オフセットの防止、および、画像濃度が低下の防止が行える。
また、上記比率（Ｖｓｐ／Ｖｓｇ）が所定の値以下でも、強制トナー消費動作の実行の回数に基づき強制トナー消費動作の実行を強制的に終了する。これは、例えば、Ｐセンサ不良があり、上記比率（Ｖｓｐ／Ｖｓｇ）を正確に検出できなかった場合、強制トナー消費動作を強制終了させる動作がないと、トナー消費動作を際限なく繰り返してしまう不具合が発生する可能性がある。そこで、強制トナー消費動作の実行回数に基づき強制終了させるモードを設け、上記問題の発生を防ぐリミッターの役割を呈するようにする。
また、回収トナー搬送路１５に開閉可能なシャッターを設け、強制トナー消費動作の実行中はシャッターを閉じるようにすることで、より確実に回収トナーが現像装置２に戻らないようにする。
また、トナー消費用パターンは、主走査方向に長く、副走査方向に短い長方形の画像パターンを複数、副走査方向に間隔をもって配置したものとする。トナー消費用パターンを回収するクリーニングブレード６は、画像形成時の転写残トナーをクリーニングする機能は備えているが、トナー消費用パターンのような実画像をクリーニングしようとすると、トナー量が多くなって負荷が大きくなり、クリーニング不良やクリーニングブレード６からのトナーのすり抜けが発生しやすくなる。そこで、このようなクリーニング不良やクリーニングブレード６からのトナーのすり抜けが発生し難いトナー消費用パターンとする。上述する実験の結果、同じ画像面積であっても、ベタ画像に比べ、主走査方向に長く、副走査方向に短い長方形の画像を副走査方向に間隔をもって配置したものが、クリーニングブレード６へ負荷が小さくなることが判った。
また、トナー消費用パターンを、感光体１に接触するよう配置される分離爪１１部分を避けるように主走査方向に複数に分割したものとする。これにより、トナー消費用パターン像がクリーニングブレード６まで移動する間に、分離爪１１をトナーで汚してしまうことを防止し、分離爪１１の汚れによる異常画像の発生を防止する。
また、新品検知手段により現像装置２が新品と検知された時におこなう新品現像装置の立ち上げ動作中に、強制トナー消費動作を実行することにより、画像形成可能になるまでの時間を短くすることができる。
また、感光体１と、現像装置２と、クリーニング装置７とを一体的に支持して形成し、画像形成装置に脱着可能なプロセスカートリッジとする。このようなプロセスカートリッジの形態をとることで、現像装置２の交換と、クリーニング装置７の交換とが同時に行え、強制トナー消費動作実行中に、クリーニング装置７内のトナー回収コイル１０の周辺空間１０ａの回収トナー貯留手段への貯留が簡単におこなえる。また、メンテナンスを容易に行うことができるというメリットがある。 As described above, according to the present embodiment, when the developing device 2 is detected as new by the new product detection means, a predetermined toner consumption pattern is formed on the photoreceptor 1 and is collected by the cleaning blade 6. Then, a forced toner consumption operation for forcibly consuming the toner in the developing device 2 is executed in a state where the collected toner is stored in the collected toner storage means. By executing the forced toner consumption operation in a state where the collected toner is not temporarily returned to the developing device 2 in this way, the toner density in the developing device 2 can be lowered. Therefore, the toner charge amount of the initial developer can be increased, the toner adhesion amount on the photoreceptor 1 can be suppressed, and the toner adhesion amount on the recording medium can be decreased. Accordingly, even in an image forming apparatus that performs toner recycling, fixing offset due to the initial developer can be prevented.
In addition, a selection unit that can select whether to execute the forced toner consumption operation from the outside is provided, and before executing the forced toner consumption operation, it is determined whether the execution of the forced toner consumption operation is necessary based on the selection result of the selection unit. The forced toner consumption operation is executed based on the result. This is because when the forced toner consumption operation is performed, the image density may decrease due to a decrease in the toner adhesion amount, and some users always prioritize the occurrence of a decrease in image density over the occurrence of a fixing offset. Sometimes you think. In order to respond to such user needs, a forced toner consumption operation is executed based on the selection result of the selection means.
Further, developer information input means for inputting information for identifying the date of manufacture of the developer accommodated when the developing device 2 is replaced from the outside is provided, and the developer information input means before executing the forced toner consumption operation. Based on the input information, the date of manufacture of the developer is identified to determine whether the forced toner consumption operation needs to be executed, and the forced toner consumption operation is executed based on the determination result. In addition, the developer information identifying member that can identify the date of manufacture of the developer accommodated in the developing device 2 is provided, and the developer information identifying member can manufacture the developer year before executing the forced toner consumption operation. The date and time are identified to determine whether the forced toner consumption operation needs to be executed, and the forced toner consumption operation is executed based on the determination result. In these cases, even when the developing device 2 is new, if the leaving time is short, the decrease in the toner charge amount is small, and fixing offset may not occur. In such a case, if the forcible toner consumption operation is executed, the toner charge amount may increase excessively, which may cause a side effect that the image density decreases. This corresponds to the case where the initial developer leaving time is short.
Further, during execution of the forced toner consumption operation, a P pattern is formed on the photosensitive member 1 by the developing device 2, and the toner adhesion amount of the P pattern is detected by the P sensor 8, and the detection result becomes a predetermined target value. In this case, the execution of the forced toner consumption operation is terminated. This is because, even if the developing device 2 is new, the toner charge amount decreases little depending on the leaving environment other than the above-described leaving time, and the toner adhesion amount does not become excessive and fixing offset may not occur. Therefore, the toner adhesion amount on the photosensitive member 1 is detected before the forced toner consumption operation is executed, and it is determined whether or not the forced toner consumption operation is required based on this. As described above, in the case where the necessity of executing the forced toner consumption operation is determined based on the detection result of the toner adhesion amount by the P sensor 8, the toner density can be adjusted based on the actual toner adhesion amount. Even if there is a difference in environment, fixing offset can be prevented more effectively. Further, since the end of execution of the forced toner consumption operation is determined based on the detection result of the toner adhesion amount by the P sensor 8, it is possible to effectively prevent the side effect that the toner charge amount increases too much and the image density decreases. .
Further, the P pattern creation and the detection of the toner adhesion amount by the P sensor, and the execution of the forced toner consumption operation, which are performed to determine the end of the execution of the forced toner consumption operation, are alternately performed. Further, the P pattern creation, the detection of the toner adhesion amount by the P sensor, and the execution of the forced toner consumption operation, which are performed to determine the end of the execution of the forced toner consumption operation, are performed a plurality of times. As a result, execution and termination of the forced toner consumption operation can be accurately determined, and effective fixing offset can be prevented and image density can be prevented from lowering.
Further, the P sensor 8 detects the pattern portion detection value (Vsp) and the background portion detection value (Vsg) of the P pattern, and when the ratio (Vsp / Vsg) exceeds a predetermined value, the detection result is It is determined that the target value has been reached. As described above, since the pattern portion detection value (Vsp) and the background portion detection value (Vsg) are used, it is possible to accurately determine whether the forced toner consumption operation is executed and ended, and to effectively prevent the fixing offset, and Therefore, the image density can be prevented from being lowered.
Even if the ratio (Vsp / Vsg) is equal to or less than a predetermined value, the forced toner consumption operation is forcibly terminated based on the number of executions of the forced toner consumption operation. For example, if there is a P sensor failure and the ratio (Vsp / Vsg) cannot be detected accurately, the toner consumption operation will be repeated indefinitely if there is no operation to forcibly terminate the forced toner consumption operation. May occur. Therefore, a mode for forcibly ending based on the number of executions of the forced toner consumption operation is provided to serve as a limiter that prevents the occurrence of the above problem.
Further, a shutter that can be opened and closed is provided in the collected toner conveyance path 15, and the shutter is closed during execution of the forced toner consumption operation, so that the collected toner does not return to the developing device 2 more reliably.
Further, it is assumed that the toner consumption pattern includes a plurality of rectangular image patterns that are long in the main scanning direction and short in the sub scanning direction and spaced apart in the sub scanning direction. The cleaning blade 6 that collects the toner consumption pattern has a function of cleaning the transfer residual toner at the time of image formation. However, when an actual image such as the toner consumption pattern is to be cleaned, the amount of toner increases. The load is increased, and cleaning failure and toner slipping from the cleaning blade 6 are likely to occur. Therefore, a toner consumption pattern in which such poor cleaning and toner slip-out from the cleaning blade 6 hardly occur is set. As a result of the above-described experiment, even when the image area is the same, a rectangular image that is longer in the main scanning direction and shorter in the sub scanning direction than the solid image is arranged at intervals in the sub scanning direction. Was found to be smaller.
Further, it is assumed that the toner consumption pattern is divided into a plurality of parts in the main scanning direction so as to avoid the separation claw 11 portion arranged so as to be in contact with the photoreceptor 1. This prevents the separation claw 11 from being stained with toner while the toner consumption pattern image moves to the cleaning blade 6, and prevents the occurrence of abnormal images due to the contamination of the separation claw 11.
Further, during the start-up operation of the new developing device that is performed when the developing device 2 is detected as new by the new product detecting means, the time until image formation becomes possible can be shortened by executing the forced toner consumption operation. it can.
Further, the photosensitive member 1, the developing device 2, and the cleaning device 7 are integrally supported to form a process cartridge that can be attached to and detached from the image forming apparatus. By adopting such a process cartridge configuration, the developing device 2 and the cleaning device 7 can be replaced at the same time, and the peripheral space 10a of the toner recovery coil 10 in the cleaning device 7 can be replaced during the forced toner consumption operation. Can be easily stored in the collected toner storage means. Further, there is an advantage that maintenance can be easily performed.

本実施形態に係る画像形成装置の像担持体周辺の概略構成をしめす断面図。1 is a cross-sectional view showing a schematic configuration around an image carrier of an image forming apparatus according to an embodiment. トナーリサイクル機構を説明するための斜視図。The perspective view for demonstrating a toner recycling mechanism. 画像形成に先立つ前処理動作中の強制トナー消費動作のフローチャート。10 is a flowchart of a forced toner consumption operation during a pre-processing operation prior to image formation. 前処理動作中の強制トナー消費動作の変形例のフローチャート。9 is a flowchart of a modified example of forced toner consumption operation during pre-processing operation. 前処理動作中の強制トナー消費動作の変形例のフローチャート。9 is a flowchart of a modified example of forced toner consumption operation during pre-processing operation. 前処理動作中の強制トナー消費動作の変形例のフローチャート。9 is a flowchart of a modified example of forced toner consumption operation during pre-processing operation. 前処理動作中の強制トナー消費動作の変形例のフローチャート。9 is a flowchart of a modified example of forced toner consumption operation during pre-processing operation. （Ｖｓｐ／Ｖｓｇ）値と定着オフセットランクの関係を示したグラフ。The graph which showed the relationship between a (Vsp / Vsg) value and a fixing offset rank. （Ｖｓｐ／Ｖｓｇ）値とベタ濃度ＩＤとの関係を示したグラフ。The graph which showed the relationship between (Vsp / Vsg) value and solid density | concentration ID. 前処理動作中の強制トナー消費動作の変形例のフローチャート。9 is a flowchart of a modified example of forced toner consumption operation during pre-processing operation. 強制トナー消費モードの実行回数とベタ濃度ＩＤの関係を示すグラフ。6 is a graph showing the relationship between the number of executions of forced toner consumption mode and a solid density ID. (ａ)、（ｂ）、（ｃ）トナー消費用パターン(a), (b), (c) Toner consumption pattern 分離爪がある場合のトナー消費用パターンToner consumption pattern with separation nails

Explanation of symbols

１感光体
２現像装置
３レーザー光
４帯電ローラ
５除電ランプ
６クリーニングブレード
７クリーニング装置
８Ｐセンサ
９トナー回収羽根
１０トナー回収コイル
１０ａトナー回収コイルの周辺空間（回収トナー貯留手段）
１１分離爪
１２拍車
１３帯電ローラクリーニングパット
１４転写ベルト
１５回収トナー搬送路
１６トナー収容部
１７第２ブレード DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Developing device 3 Laser beam 4 Charging roller 5 Static elimination lamp 6 Cleaning blade 7 Cleaning device 8 P sensor 9 Toner collection blade 10 Toner collection coil 10a Space around the toner collection coil (collected toner storage means)
DESCRIPTION OF SYMBOLS 11 Separation claw 12 Spur 13 Charging roller cleaning pad 14 Transfer belt 15 Collected toner conveyance path 16 Toner container 17 Second blade

Claims

An image carrier for carrying a latent image, a developing device for converting the latent image into a toner image using a two-component developer containing toner and carrier, and a toner for supplying toner to the two-component developer in the developing device Replenishing means, transfer means for directly or indirectly transferring a toner image on the image carrier onto a recording medium, a fixing device for fixing an unfixed toner image on the recording medium, and on the image carrier A cleaning unit that cleans and collects the toner remaining after the transfer, a recovery toner transport path that transports the toner collected by the cleaning unit to the developing device, and a control unit that controls these, and is provided at any timing. In an image forming apparatus that replaces a developing device with a new one,
New developing device detecting means for detecting whether or not the developing device is new, toner consumption pattern forming means for forming a predetermined toner consumption pattern on the image carrier by the developing device, and recovery by the cleaning means Recovered toner storage means for storing the toner, and when the developing device is detected as new by the developing device new article detecting means, the image carrying member is formed by the toner consuming pattern forming means when the developing device is detected as new. A toner consumption pattern is formed thereon, the toner consumption pattern is collected by the cleaning unit, and the collected toner is stored in the collected toner storage unit to forcibly consume the toner in the developing device. An image forming apparatus controlled to execute a forced toner consumption operation.

2. The image forming apparatus according to claim 1, further comprising a selection unit that can select whether to execute the forced toner consumption operation from the outside, wherein the control unit is configured based on a selection result of the selection unit before executing the forced toner consumption operation. An image forming apparatus comprising: determining whether or not execution of the forced toner consumption operation is necessary and controlling to execute the forced toner consumption operation based on the determination result.

The image forming apparatus according to claim 1 or 2, further comprising developer information input means for inputting, from the outside, information capable of identifying the date of manufacture of the two-component developer accommodated in the developing device when the developing device is replaced. The controller determines whether or not the forced toner consumption operation needs to be executed by identifying the date of manufacture of the developer based on the information input by the developer information input means before the forced toner consumption operation. And controlling to execute the forced toner consumption operation based on the determination result.

3. The image forming apparatus according to claim 1, further comprising a developer information identifying member capable of identifying a date of manufacture of a two-component developer accommodated in the developing device, wherein the control unit includes the forced toner consumption. Prior to the execution of the operation, the developer information identification member identifies the date of manufacture of the developer to determine whether or not the forced toner consumption operation needs to be executed, and the forced toner consumption operation is executed based on the determination result. An image forming apparatus that is controlled as described above.

5. The image forming apparatus according to claim 1, wherein a toner adhesion amount detection pattern forming means for forming a toner adhesion amount detection pattern at a predetermined position on the image carrier by the developing device, and the toner adhesion amount detection. Toner adhesion amount detection means for detecting the toner adhesion amount of the pattern, and the control unit forms a toner adhesion amount detection pattern by the toner adhesion amount detection pattern formation means before executing the forced toner consumption operation; The toner adhesion amount detection means detects the toner adhesion amount of the toner adhesion amount detection pattern, and the forced toner consumption operation is not executed when the detection result by the toner adhesion amount detection means reaches a predetermined target value. An image forming apparatus that is controlled as described above.

6. The image forming apparatus according to claim 5, wherein the control unit is configured to execute the forced toner consumption operation and the toner adhesion amount detection pattern by the toner adhesion amount detection means for determining execution of the forced toner consumption operation. An image forming apparatus that controls to perform toner adhesion amount detection operation alternately.

7. The image forming apparatus according to claim 6, wherein the controller is configured to execute the forced toner consumption operation and the toner adhesion amount detection pattern by the toner adhesion amount detection unit for determining whether to execute the forced toner consumption operation. An image forming apparatus that controls to perform a toner adhesion amount detection operation a plurality of times.

8. The image forming apparatus according to claim 5, wherein the control unit is configured so that the toner adhesion amount detection means other than the toner adhesion amount detection value (Vsp) of the toner adhesion amount detection pattern and the toner adhesion amount detection pattern part. The toner adhesion amount detection value (Vsg) of the image carrier portion is detected, and when the ratio (Vsp / Vsg) is equal to or greater than a predetermined value, it is determined that the detection result has reached a predetermined target value. An image forming apparatus.

9. The image forming apparatus according to claim 8, wherein the controller forcibly executes the forced toner consumption operation based on the number of executions of the forced toner consumption operation even when the ratio (Vsp / Vsg) is equal to or less than a predetermined value. An image forming apparatus that is controlled to end.

10. The image forming apparatus according to claim 1, wherein a shutter that can be opened and closed is provided in the collected toner conveyance path, and the shutter is opened during the forced toner consumption operation. An image forming apparatus characterized by closing.

11. The image forming apparatus according to claim 1, wherein the toner consuming pattern formed on the image carrier by the toner consuming pattern forming means is: An image forming apparatus comprising a plurality of rectangles that are long in the main scanning direction and short in the sub scanning direction and spaced apart in the sub scanning direction.

12. The image forming apparatus according to claim 11, further comprising a separation unit that contacts a region downstream of the transfer position of the image carrier and upstream of the cleaning position, and corresponds to the separation unit in the main scanning direction of the toner consumption pattern. An image forming apparatus characterized in that an interval is provided at a position where the toner consumption pattern does not contact the separation means.

13. The image forming apparatus according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, wherein the control unit detects that the developing device is new by the developing device new article detecting means. An image forming apparatus, wherein the forced toner consumption operation is controlled to be executed during the start-up operation of the new developing device that is performed.

A process cartridge formed by integrally supporting an image carrier, a developing device, and a cleaning unit, and detachable from the image forming device,
A process cartridge which is employed in the image forming apparatus according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13.