JP2016014706A5

JP2016014706A5 -

Info

Publication number: JP2016014706A5
Application number: JP2014135530A
Authority: JP
Filing date: 2014-07-01
Publication date: 2017-01-12

Description

上述した課題を解決するために、本発明は、表面移動する潜像担持体と、画像情報に基づいて前記潜像担持体の表面にトナー画像を形成するトナー画像形成手段と、表面移動する中間転写体と、前記潜像担持体と前記中間転写体とが対向する一次転写領域に一次転写バイアスを印加することによって該一次転写領域で前記潜像担持体上のトナー画像を中間転写体へ一次転写させる一次転写手段と、前記中間転写体と二次転写部材とが対向する二次転写領域に二次転写バイアスを印加することによって該二次転写領域で前記中間転写体上のトナー画像を記録材へ二次転写させる二次転写手段と、前記二次転写領域へ記録材を搬送する記録材搬送手段とを有する画像形成装置において、トナー画像先端部分におけるトナー付着量情報を取得し、取得したトナー付着量情報から得られる単位面積当たりのトナー付着量が規定量未満である場合には、該トナー画像先端部分を一次転写させる時に流す一次転写電流を、該トナー画像先端部分よりも後端側で同じトナー付着量情報に対応するトナー画像部分を一次転写させる時に流す一次転写電流よりも大きくする一次転写電流制御手段を有することを特徴とする。 In order to solve the above-described problems, the present invention provides a latent image carrier that moves on the surface, a toner image forming unit that forms a toner image on the surface of the latent image carrier based on image information, and an intermediate that moves on the surface. By applying a primary transfer bias to a transfer body, and a primary transfer area where the latent image carrier and the intermediate transfer body face each other, a toner image on the latent image carrier is primarily transferred to the intermediate transfer body in the primary transfer area. A toner image on the intermediate transfer body is recorded in the secondary transfer area by applying a secondary transfer bias to a primary transfer means for transferring, and a secondary transfer area where the intermediate transfer body and the secondary transfer member face each other. in the image forming apparatus having a secondary transfer means for secondarily to timber transfer, and a recording material conveying means for conveying the recording material to the secondary transcription regions, obtains the toner adhesion amount information of the toner image tip section, taken When the toner adhesion amount per unit area obtained from the toner adhesion amount information is less than a specified amount, the primary transfer current that flows when the toner image leading edge portion is primarily transferred is rearward of the toner image leading edge portion. And a primary transfer current control means for making the toner image portion corresponding to the same toner adhesion amount information larger than a primary transfer current to be passed when primary transfer is performed.

以上に説明したものは一例であり、本発明は、次の態様毎に特有の効果を奏する。
（態様Ａ）
表面移動する感光体１Ｙ，１Ｍ，１Ｃ，１Ｋ等の潜像担持体と、画像情報に基づいて前記潜像担持体の表面にトナー画像を形成する帯電装置２Ｙ，２Ｍ，２Ｃ，２Ｋ、光書込ユニット２０、現像装置５Ｙ，５Ｃ，５Ｍ，５Ｋ等のトナー画像形成手段と、表面移動する中間転写ベルト８等の中間転写体と、前記潜像担持体と前記中間転写体とが対向する一次転写ニップ等の一次転写領域に一次転写バイアスを印加することによって該一次転写領域で前記潜像担持体上のトナー画像を中間転写体へ一次転写させる一次転写ローラ９Ｙ，９Ｍ，９Ｃ，９Ｋ等の一次転写手段と、前記中間転写体と二次転写ベルト２０４等の二次転写部材とが対向する二次転写ニップ等の二次転写領域に二次転写バイアスを印加することによって該二次転写領域で前記中間転写体上のトナー画像を転写紙Ｐ等の記録材へ二次転写させる二次転写装置２００等の二次転写手段と、前記二次転写領域へ記録材を搬送する上部入口ガイド３４Ａ、下部入口ガイド３４Ｂ、レジストローラ対３３等の記録材搬送手段とを有する画像形成装置において、トナー画像先端部分におけるトナー付着量情報を取得し、取得したトナー付着量情報から得られる単位面積当たりのトナー付着量（画像面積率等）が規定量（１００％）未満である場合には、該トナー画像先端部分を一次転写させる時に流す一次転写電流を、該トナー画像先端部分よりも後端側で同じトナー付着量情報に対応するトナー画像部分を一次転写させる時に流す一次転写電流よりも大きくする制御部４００等の一次転写電流制御手段を有することを特徴とする。
本発明者らの研究によれば、記録材先端が二次転写領域へ進入した直後に記録材の跳ね上がりによる気流で中間転写体上のトナー画像先端部分が乱される先端チリは、当該トナー画像先端部分の画像面積率が低い場合（単位面積当たりのトナー付着量が少ない場合）に顕著に現れる。これは次の理由によるものと考えることができる。すなわち、中間転写体に対する個々のトナーの付着力は、自らの帯電量のみならず、その周囲に存在するトナーの帯電量にも影響を受ける。詳しくは、付着力に影響を受ける所定の近接範囲内に存在するトナーの数が多いトナーほど、その付着力が大きくなる。単位面積当たりのトナー付着量が少ない場合、所定の近接範囲内に存在するトナー数が少ないトナーが多く存在し得るため、中間転写体に対する付着力の弱いトナーが多く存在する。よって、比較的弱い気流が当たるだけでトナー像が容易に乱れてしまう。そのため、当該トナー画像先端部分の画像面積率が低い場合、安定した搬送品質を確保できる範囲で記録材搬送手段の構成を最適化しても、先端チリを十分に抑制することは困難である。
これに対し、トナー画像先端部分の画像面積率が高い場合（単位面積当たりのトナー付着量が多い場合）には、所定の近接範囲内に存在するトナー数が多いトナーが多数存在し得るため、中間転写体に対する付着力の強いトナーが多数存在する。よって、ある程度の強い気流が当たってもトナー像が乱されることがない。そのため、当該トナー画像先端部分の画像面積率が高い場合には、安定した搬送品質を確保できる範囲で記録材搬送手段の構成を最適化することで、先端チリを十分に抑制することができる。
一方で、トナー画像先端部分についての一次転写電流を大きくして先端チリを抑制しようとする場合、そのトナー画像先端部分の画像面積率が高いと、一次転写電流量の増加に対する一次転写効率の低下度合いが大きいため、そのトナー画像先端部分において画像濃度低下を引き起こす。しかしながら、そのトナー画像先端部分の画像面積率が低い場合には、一次転写電流量の増加に対する一次転写効率の低下度合いが小さいので、そのトナー画像先端部分における画像濃度低下が問題とならない。
そこで、本態様では、トナー画像先端部分のトナー付着量情報から得られる単位面積当たりのトナー付着量が規定量未満である場合、そのトナー画像先端部分についての一次転写電流を、そのトナー画像先端部分よりも後端側で同じトナー付着量情報に対応するトナー画像部分を一次転写させる時に流す一次転写電流よりも大きくする。本態様によれば、トナー画像先端部分の画像面積率が低い場合に、記録材搬送手段の構成を最適化する方法では十分に抑制することが困難な先端チリについて、一次転写電流を大きくすることで抑制できる。そして、トナー画像先端部分の画像面積率が低い場合には、上述したように、一次転写電流が大きくても画像濃度低下が問題とならない。一方、トナー画像先端部分の画像面積率が高い場合、一次転写電流を大きくすることによる画像濃度低下が発生しやすいが、先端チリについては記録材搬送手段の構成を最適化する方法等によりを十分に抑制することが容易である。したがって、トナー画像先端部分の画像面積率が高い場合には、一次転写電流を大きくしないことにより、画像濃度低下を抑制しつつ先端チリを十分に抑制できる。 What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
Latent image carriers such as photoreceptors 1Y, 1M, 1C, and 1K that move on the surface, and charging devices 2Y, 2M, 2C, and 2K that form toner images on the surface of the latent image carrier based on image information, optical writing Toner image forming means such as the image forming unit 20, developing devices 5Y, 5C, 5M, and 5K, an intermediate transfer member such as the intermediate transfer belt 8 that moves on the surface, and the latent image carrier and the intermediate transfer member facing each other. A primary transfer roller 9Y, 9M, 9C, 9K, etc. that applies a primary transfer bias to a primary transfer area such as a transfer nip to primarily transfer a toner image on the latent image carrier to an intermediate transfer body in the primary transfer area. By applying a secondary transfer bias to a secondary transfer area such as a secondary transfer nip where the primary transfer means and the intermediate transfer member and a secondary transfer member such as the secondary transfer belt 204 face each other, the secondary transfer area In the above A second transfer means such as a secondary transfer device 200 to the toner image on between transfer member is secondarily transferred to a recording material such as transfer paper P, the upper inlet guide 34A for conveying the recording material to the secondary transcription region, In the image forming apparatus having the lower entrance guide 34B and the recording material conveying means such as the registration roller pair 33, the toner adhesion amount information at the front end portion of the toner image is acquired, and the toner per unit area obtained from the acquired toner adhesion amount information When the adhesion amount (image area ratio, etc.) is less than a prescribed amount (100%), the primary transfer current that flows when the toner image front end portion is primarily transferred is the same on the rear end side than the toner image front end portion. The image forming apparatus includes a primary transfer current control unit such as a control unit 400 that makes the toner image portion corresponding to the toner adhesion amount information larger than a primary transfer current that flows when primary transfer is performed. .
According to the studies by the present inventors, the front end dust where the front end portion of the toner image on the intermediate transfer member is disturbed by the air flow caused by the jump of the recording material immediately after the front end of the recording material enters the secondary transfer region This is noticeable when the image area ratio of the front end portion is low (when the toner adhesion amount per unit area is small). This can be attributed to the following reason. That is, the adhesion force of each toner to the intermediate transfer member is influenced not only by the charge amount of itself but also by the charge amount of the toner existing around it. Specifically, a toner having a larger number of toners within a predetermined proximity range affected by the adhesive force has a higher adhesive force. When the toner adhesion amount per unit area is small, there can be many toners with a small number of toners present in a predetermined proximity range, and therefore there are many toners with weak adhesion to the intermediate transfer member. Therefore, the toner image is easily disturbed only by a relatively weak airflow. For this reason, when the image area ratio of the front end portion of the toner image is low, it is difficult to sufficiently suppress the front end dust even if the configuration of the recording material transport unit is optimized within a range where stable transport quality can be ensured.
On the other hand, when the image area ratio of the front end portion of the toner image is high (when the toner adhesion amount per unit area is large), there can be many toners having a large number of toners within a predetermined proximity range. There are many toners having strong adhesion to the intermediate transfer member. Therefore, the toner image is not disturbed even when a certain amount of strong airflow is applied. Therefore, when the image area ratio of the leading edge portion of the toner image is high, the leading edge dust can be sufficiently suppressed by optimizing the configuration of the recording material conveying means within a range where stable conveying quality can be ensured.
On the other hand, when increasing the primary transfer current at the leading edge of the toner image to suppress leading dust, if the image area ratio at the leading edge of the toner image is high, the primary transfer efficiency decreases with respect to the increase in the primary transfer current amount. Since the degree is large, a reduction in image density is caused at the front end portion of the toner image. However, when the image area ratio at the front end portion of the toner image is low, the degree of decrease in the primary transfer efficiency with respect to the increase in the primary transfer current amount is small.
Therefore, in this aspect, when the toner adhesion amount per unit area obtained from the toner adhesion amount information of the toner image front end portion is less than the specified amount, the primary transfer current for the toner image front end portion is determined as the toner image front end portion. More than the primary transfer current that flows when the toner image portion corresponding to the same toner adhesion amount information is primarily transferred on the rear end side. According to this aspect, when the image area ratio of the front end portion of the toner image is low, the primary transfer current is increased for the front end dust that is difficult to sufficiently suppress by the method of optimizing the configuration of the recording material transport unit. Can be suppressed. When the image area ratio at the front end portion of the toner image is low, as described above, even if the primary transfer current is large, there is no problem in reducing the image density. On the other hand, when the image area ratio of the front end portion of the toner image is high, the image density is likely to be lowered by increasing the primary transfer current. It is easy to suppress. Accordingly, when the image area ratio of the front end portion of the toner image is high, the front end dust can be sufficiently suppressed while suppressing the decrease in image density by not increasing the primary transfer current.

Claims

A latent image carrier that moves on the surface;
Toner image forming means for forming a toner image on the surface of the latent image carrier based on image information;
An intermediate transfer member that moves on the surface;
Primary transfer in which the toner image on the latent image carrier is primarily transferred to the intermediate transfer member in the primary transfer region by applying a primary transfer bias to a primary transfer region where the latent image carrier and the intermediate transfer member face each other. Means,
A secondary transfer bias is applied to a secondary transfer region where the intermediate transfer member and the secondary transfer member face each other, whereby a toner image on the intermediate transfer member is secondarily transferred to a recording material in the secondary transfer region. A next transfer means;
In the image forming apparatus and a recording material conveying means for conveying the recording material to the secondary transcription region,
When the toner adhesion amount information at the front end portion of the toner image is acquired, and the toner adhesion amount per unit area obtained from the acquired toner adhesion amount information is less than the specified amount, the toner image front end portion is flown at the time of primary transfer. It has primary transfer current control means for making a primary transfer current larger than a primary transfer current that flows when a toner image portion corresponding to the same toner adhesion amount information is primarily transferred on the rear end side with respect to the front end portion of the toner image. An image forming apparatus.

The image forming apparatus according to claim 1.
The primary transfer current control means acquires toner adhesion amount information of each toner image portion in the moving direction of the latent image carrier surface of the toner image corresponding to the image information based on the image information, and each toner image portion An image forming apparatus that performs primary transfer current control for controlling a transfer current that flows when passing through a primary transfer region in accordance with toner adhesion amount information of the toner image portion.

The image forming apparatus according to claim 2.
Correlation information indicating the relationship between the toner adhesion amount information and the primary transfer current, the first correlation information used for primary transfer current control when the toner image leading edge portion is primarily transferred, and the toner image leading edge portion. Storage means for storing second correlation information used for primary transfer current control at the time of primary transfer of the toner image portion on the end side,
The primary transfer current control means determines a primary transfer current to flow when the toner image leading end portion is primarily transferred based on the first correlation information, and selects a toner image portion on the rear end side of the toner image leading end portion. An image forming apparatus, wherein a primary transfer current to be passed when primary transfer is performed is determined based on the second correlation information.

The image forming apparatus according to claim 3.
Recording material type information acquisition means for acquiring type information of the recording material conveyed by the recording material conveyance means;
The storage means stores, for each type information, a plurality of types of correlation information for at least one of the first correlation information and the second correlation information,
The primary transfer current control means uses correlation information corresponding to the type information acquired by the recording material type information acquisition means when executing primary transfer current control using the at least one correlation information. An image forming apparatus.

The image forming apparatus according to claim 4.
The image forming apparatus according to claim 1, wherein the type information is information for identifying a difference between at least one of a paper thickness of the recording material, a material, and presence / absence of a coating layer.

The image forming apparatus according to claim 4 or 5,
The image forming apparatus according to claim 1, wherein the recording material type information obtaining unit accepts a user operation for specifying a type of the recording material by an operation accepting unit.

The image forming apparatus according to any one of claims 1 to 6,
The image forming apparatus, wherein the intermediate transfer member is constituted by an elastic belt having an elastic layer.