JP2004085680A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of ensuring image quality and feed reliability even when an OHP sheet or an index sheet is used as an image formation sheet. <P>SOLUTION: In the electrophotographic image forming apparatus, various conditions regarding image formation are adjusted in accordance with paper to be used when an OHP sheet is used together with an inserted sheet of blank paper or an index sheet is used, as an image formation sheet. <P>COPYRIGHT: (C)2004,JPO

Description

この構成条件における、図３に示した各条件の制御値の具体例は下記の通りである。
【００３８】
ＯＨＰ用紙時の条件
転写Ｔｏｔａｌ電流：２００μＡ
分離Ｔｏｔａｌ電流：−１７０μＡ
除電ランプ：消灯
帯電電位：−７５０Ｖ
合紙時の条件
転写Ｔｏｔａｌ電流：５０μＡ
分離Ｔｏｔａｌ電流：−２００μＡ
除電ランプ：点灯
帯電電位：−６５０Ｖ
このようにすることにより、本実施例によれば、ＯＨＰ用紙に画像形成し、白紙の合紙を利用する際に、ＯＨＰ用紙および合紙のいずれの場合にも、感光体からの分離を問題なく行うことができるという効果がある。
【００３９】
なお、図２および図３においては、転写装置３５における転写電流、分離装置３６における分離電流、除電ランプ４１の輝度および帯電装置３２における帯電電位のすべての条件を制御するようにしているが、本発明はこれに限らず、いずれか１つの条件を制御するものであってもよい。
【００４０】
次に、インデックス紙に画像形成を行う場合について説明する。
【００４１】
この画像形成装置においては、画像形成に用いる用紙の幅（紙送り方向と直角の方向の長さ）を検出する用紙幅検出手段を有し、この用紙幅検出手段による検出結果に応じて画像形成の際の諸条件を制御する。
【００４２】
図４は、図１に示した画像形成装置の第２の実施例であってインデックス紙に画像形成する場合の制御に関する構成を示すブロック図である。
【００４３】
図４に示すように、図１に示した転写装置３５および分離装置３６には高圧電源１００からの高電圧が供給され、用紙幅検出手段５７の検出結果に基づくＣＰＵ１０４からの指示によって転写装置３５および分離装置３６の駆動電圧が調節される。ユーザは操作部１０３を操作して画像形成の指示を入力する。
【００４４】
図５は、図４に示した第２の実施例における用紙幅検出手段５７の一例を示す図であり、（ａ）は用紙幅検出手段５７の斜視図、（ｂ）は用紙幅検出手段５７の断面図である。
【００４５】
図５（ａ）および図５（ｂ）において、１０は画像形成用紙としてのインデックス紙であり、図５（ａ）に示すようにインデックス紙１０は、他の部分より幅の狭い耳部１０ａを有する。このようにインデックス紙１０では不連続に用紙幅が変化している。
【００４６】
用紙幅検出手段５７は、用紙幅検出の対象のインデックス紙１０を案内する用紙ガイド板５７ａと、用紙ガイド板５７ａに設けられ光を通過させることができるスリット５７ｂと、用紙ガイド板５７ａのスリット５７ｂ上を通過する用紙の幅を光学的に検出するＬＥＤアレイ５７ｃとを有して構成され、給紙経路のうち感光体ドラム３１よりも前段の所定の位置に設けられる。
【００４７】
インデックス紙１０は、用紙ガイド板５７ａに沿って予め定めた速度（給紙線速）で進み、スリット５７の上を通過するときに、ＬＥＤアレイ５７ｃによって、その幅（紙送り方向と直角の方向の長さ）が検出される。このように、予め定めた速度でインデックス紙１０を搬送することによって、インデックス紙１０の紙送り方向の位置とその位置における用紙幅との関係が得られる。
【００４８】
なお、このように検出した、インデックス紙１０の各部分における用紙幅のうち最大の値を、以下においては「最大通紙幅」という。
【００４９】
ＣＰＵ１０４は、用紙幅の変化を検知した際、用紙幅検出手段５７から転写装置３５の転写極入り口までの距離と、給紙線速とから、インデックス紙１０のうち用紙幅が変化する部分が転写極に到達する時間を計算し、そのタイミングに合わせて転写電流値を変化させるように制御を行う。
【００５０】
また同様に、インデックス紙１０のうち用紙幅が変化する部分が分離装置３６の分離極に到達する時間を計算し、そのタイミングに合わせて分離電流値を変化させるように制御を行う。
【００５１】
ここで、本実施例の好ましい構成条件の一例を示す。

この構成条件において転写電流値は数１にしたがって求め、制御するのがよい。
【００５２】
【数１】
転写電流値＝（基準転写電流値）＋（基準転写電流値）×（０．４３Ｘ^２−０．７６Ｘ＋０．３３）
数１において、Ｘ＝（検知通紙幅）／（最大通紙幅）であり、基準転写電流値は予め定めた用紙幅が最大通紙幅である場合に用いる転写電流値である。
【００５３】
また、この構成条件において分離電流値は数２にしたがって求め、制御するのがよい。
【００５４】
【数２】
分離電流値＝（基準分離電流値）＋（基準分離電流値）×（０．４３Ｘ^２−０．７６Ｘ＋０．３３）
数２において、Ｘ＝（検知通紙幅）／（最大通紙幅）であり、基準分離電流値は予め定めた用紙幅が最大通紙幅である場合に用いる分離電流値である。
【００５５】
以上説明した制御を行うことによって、インデックス紙１０の耳部１０ａに画像形成するような場合であっても十分な転写、分離能力を発揮することができ、画質の劣化を防ぐことができる。
【００５６】
次に、用紙幅検出手段の、図５（ａ）、（ｂ）とは別の例について説明する
図６は、図４に示した第２の実施例における用紙幅検出手段５７の、図５（ａ）、（ｂ）とは別の例を示す図であり、ここでは、用紙幅検出手段１５７として示す。また、図６（ａ）は用紙幅検出手段１５７の斜視図、図６（ｂ）、（ｃ）は用紙幅検出手段１５７の断面図である。
【００５７】
図５（ａ）、（ｂ）に示した例と同様に、１０は画像形成用紙としてのインデックス紙であり、図６（ａ）に示すようにインデックス紙１０は、他の部分より幅の狭い耳部１０ａを有する。
【００５８】
用紙幅検出手段１５７は、用紙幅検出の対象のインデックス紙１０を案内する用紙ガイド板１５７ａと、用紙ガイド板１５７ａに設けられた複数の穴であるスリット１５７ｆと、用紙ガイド板１５７ａのスリット１５７ｆから突出する凸部１５７ｃを有する押下検出手段１５７ｂとを有して構成され、給紙経路のうち感光体ドラム３１よりも前段の所定の位置に設けられる。
【００５９】
押下検出手段１５７ｂの凸部１５７ｃは、上から押されるとそれに応じて下がる構造になっており、図６（ｂ）に示すように、凸部１５７ｃの上部にインデックス紙１０がない場合には、発光素子１５７ｅからの光を受光素子１５７ｄが受光し、図６（ｃ）に示すように、凸部１５７ｃの上部にインデックス紙１０がある場合には、凸部１５７ｃが押し下げられこれによって発光素子１５７ｅからの光が遮られて受光素子１５７ｄに到達せず、これによって凸部１５７ｃが押し下げられたか否かが検出される。
【００６０】
図６（ａ）に示すように、押下検出手段１５７ｂは、紙送り方向と直角方向に複数設けられており、この例では、いくつの凸部１５７ｃが押し下げられたかによって用紙幅を検出することができる構造となっている。
【００６１】
なお、この例において以降の制御は、図５（ａ）、（ｂ）を参照して説明した例と同様であるので、詳しい説明は省略する。
【００６２】
【発明の効果】
以上説明したように、本発明によれば、ＯＨＰ用紙やインデックス紙を画像形成用紙として用いる場合にも、画質、給送信頼性を確保することができる画像形成装置を提供することができる。
【００６３】
すなわち本発明によれば、ＯＨＰ用紙に画像形成する際に白紙の合紙を用いる場合であっても、ＯＨＰ用紙および合紙の感光体からの分離をスムーズに行うことができ、これに起因する紙詰まりをなくすことができるという効果がある。
【００６４】
また本発明によれば、インデックス紙の他の部分よりも幅の狭い耳部に画像形成するような場合であっても十分な転写、分離能力を発揮することができ、画質の劣化を防ぐことができる。
【図面の簡単な説明】
【図１】本発明による画像形成装置の一実施の形態の構成を示す概略断面図である。
【図２】図１に示した画像形成装置の第１の実施例であってＯＨＰ用紙に画像形成する際に合紙を利用する場合の制御に関する構成を示すブロック図である。
【図３】図２に示した第１の実施例における制御概念のタイムチャートを示す図である。
【図４】図１に示した画像形成装置の第２の実施例であってインデックス紙に画像形成する場合の制御に関する構成を示すブロック図である。
【図５】図４に示した第２の実施例における用紙幅検出手段の一例を示す図であり、（ａ）は用紙幅検出手段の斜視図、（ｂ）は用紙幅検出手段の断面図である。
【図６】図４に示した第２の実施例における用紙幅検出手段の、図５（ａ）、（ｂ）とは別の例を示す図であり、（ａ）は用紙幅検出手段の斜視図、（ｂ）、（ｃ）は用紙幅検出手段の断面図である。
【符号の説明】
１　自動原稿搬送部
１１　原稿給紙台
１２　送り出しローラ
１３　レジストローラ
１４　搬送ドラム
１５　排紙台
２　画像読取部
２３ａ　光源
２３ｂ　ミラー
２３　第１ミラーユニット
２４ａ　ミラー
２４ｂ　ミラー
２４　第２ミラーユニット
２５　結像レンズ
２６　撮像素子
２７静止原稿台
３　画像形成部
３１　感光体ドラム
３２　帯電装置
３３　露光装置
４０　現像装置
１９　手差し給紙トレイ
７　本体給紙トレイ
７ａ、７ｂ、７ｃ　本体給紙トレイ
５１Ａ、５１Ｂ、５１Ｃ　給紙ローラ
５５　搬送ローラ
５６　レジストローラ
３９　搬送ローラ
３５　転写装置
４１　除電ランプ（ＴＳＬ）
３６　分離装置
３８　定着装置
３８ａ、３８ｂ　定着用ローラ
３８ｃ　ヒーター
６　排出部
６１　定着排紙ローラ
６４　排紙トレイ
３７　クリーニング装置
１００　高圧電源
１０１、１０３　操作部
１０２、１０４　ＣＰＵ
１０　インデックス紙
１０ａ　耳部
５７　用紙幅検出手段
５７ａ　用紙ガイド板
５７ｂ　スリット
５７ｃ　ＬＥＤアレイ
１５７　用紙幅検出手段
１５７ａ　用紙ガイド板
１５７ｂ　押下検出手段
１５７ｃ　凸部
１５７ｄ　受光素子
１５７ｅ　発光素子
１５７ｆ　スリット[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus for forming an image on paper by an electrophotographic method.
[0002]
[Prior art]
A latent image is formed by irradiating light onto the photosensitive layer of a uniformly charged photoreceptor, toner is adhered to the photosensitive layer, developed, and transferred to paper to form an image in a copying machine or the like. A photographic image forming apparatus is well known.
[0003]
Conventionally, as a sheet used for image formation in such an image forming apparatus, a normal rectangular sheet of paper conforming to a certain standard has conventionally been used.
[0004]
However, recently, applications for forming images on paper of various qualities and shapes have been increasing. For example, an OHP sheet which is a transparent sheet for projecting and showing an image to a plurality of persons, or a sheet used as a partition for filing a document, and an ear portion for writing an index on one side of the sheet. And index paper.
[0005]
Also, in such a situation, if OHP sheets are stacked immediately after image formation, they are attracted to each other due to static electricity or the like and are difficult to handle. Therefore, when the paper is discharged after the image is formed on the OHP paper, a normal paper is discharged and inserted between the OHP papers (hereinafter, the inserted paper is referred to as “interleaf paper”). There is known a method of preventing OHP sheets from directly touching each other, thereby improving ease of handling.
[0006]
[Problems to be solved by the invention]
By the way, in the electrophotographic image forming apparatus, as described above, a transfer process of adsorbing a sheet on a photoconductor and transferring a developed image on the photoconductor to the sheet, and thereafter, transferring the transferred sheet from the photoconductor. A separation process for separating is required.
[0007]
If the transfer process and the separation process are not performed properly, the image quality may be degraded due to poor transfer of the image to the paper, and the paper may be jammed due to the poor separation of the paper from the photoconductor.
[0008]
However, as described above, the conventional image forming apparatus does not support applications such as using an interleaf when forming an image on an OHP sheet or forming an image on an index sheet. .
[0009]
For example, when an interleaf is used when forming an image on an OHP sheet, and when a blank sheet set in the paper feed tray is ejected as the interleaf, the interleaf is conveyed along the same path as the sheet on which the normal image is formed. Then, after the interleaving paper attracted to the photoconductor is separated from the photoconductor by a separation process, the paper is discharged.
[0010]
However, OHP paper is charged for image transfer, but it is not charged on blank paper because there is no need to transfer the image, and the quality difference between OHP paper and interleaf paper is also high. Therefore, in the conventional image forming apparatus, when the OHP paper and the interleaf are alternately conveyed, the interleaf is not smoothly separated from the photoconductor, and a paper jam may occur. there were.
[0011]
Also, in the case of forming an image on an index sheet, when the index sheet is supplied to the photoreceptor for image transfer, the edge of the index sheet is weakly attracted to the curved surface of the photoreceptor surface, and an image is to be formed on the ear. However, there is a problem that the image transfer may not be performed normally.
[0012]
The present invention has been made in view of the above points, and has as its object to provide an image forming apparatus capable of securing image quality and feeding reliability even when OHP paper or index paper is used as image forming paper. And
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a photoconductor, a charging device for charging the photoconductor, a developing device for converting an electrostatic latent image formed on the photoconductor into a toner image, and a developing device. A transfer device for transferring a toner image onto a sheet, a separation device for separating the photosensitive member from the sheet, a static elimination lamp for irradiating the photosensitive member after development and before separation, and an operation unit operated and input by a user And an electrophotographic image forming apparatus having a control unit for controlling image formation based on an input from the operation unit, wherein the operation unit uses OHP paper as the paper, The control section has a mode input means for inputting the use of OHP paper as the paper by the mode input means and using a blank interleaf paper at the time of discharge. If the previous The charging potential of the charging device, the transfer current of the transfer device, the transfer current of the separation device, and the like, when forming an image on an OHP sheet and discharging the sheet, and when discharging a white sheet inserted between each of the OHP sheets. At least one of the separation current and the luminance of the static elimination lamp is made different.
[0014]
Further, in the invention according to the first aspect, the charging potential when the control unit discharges a blank sheet to be inserted between each of the OHP sheets is determined by forming an image on the OHP sheet and discharging. It is characterized in that it is controlled to be lower than the charging potential when paper is formed.
[0015]
Further, in the invention according to claim 1, the transfer current when the control section discharges a blank sheet inserted between each of the OHP sheets is formed by forming an image on the OHP sheet and discharging. The transfer current is controlled to be lower than the transfer current when paper is formed.
[0016]
Further, in the invention according to claim 1, the separation current when the control section discharges a blank sheet inserted between each of the OHP sheets is formed by forming an image on the OHP sheet and discharging. The present invention is characterized in that control is performed so as to be higher than the separation current when paper is formed.
[0017]
Further, in the invention according to claim 1, the control section may control the brightness of the discharge lamp when discharging a blank sheet inserted between each of the OHP sheets to form an image on the OHP sheet. The discharge lamp is controlled so as to have a higher luminance than the luminance of the discharge lamp when the paper is discharged.
[0018]
Further, according to the present invention, a photoconductor, a charging device for charging the photoconductor, a developing device for converting an electrostatic latent image formed on the photoconductor into a toner image, and transferring the toner image by the developing device to a paper sheet An electrophotographic system including a transfer device, a separation device that separates the photoconductor and the sheet, an operation unit that is operated by a user, and a control unit that controls image formation based on an input from the operation unit. The image forming apparatus according to claim 1, further comprising a sheet width detecting unit configured to detect a length of the sheet in a direction perpendicular to a sheet feeding direction as a sheet width, wherein the control unit performs the transfer based on a detection result by the sheet width detecting unit. The present invention is characterized in that a transfer current by the device and a separation current by the separation device are controlled.
[0019]
Further, in the invention according to claim 6, the paper is such that the paper width changes discontinuously, and the paper width detecting means detects the discontinuous change in paper width. There is a feature.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a schematic sectional view showing a configuration of an embodiment of an image forming apparatus according to the present invention. In this embodiment, an electrophotographic copying machine will be described as an example of an image forming apparatus.
[0022]
Here, the configuration and basic operation of the image forming apparatus according to the present embodiment will be described with reference to FIG.
[0023]
When a user operates a later-described operation unit provided in the image forming apparatus and inputs a copy instruction, the original is placed on the original feeder plate 11 of the automatic original feeder 1 with the image surface facing upward, and the original is sent out by a feed roller. The sheet is fed out one by one by the operation of 12, is stopped once by the registration roller 13, is trimmed, and is then conveyed to the conveying drum 14, where it is integrated along the surface of the conveying drum 14, and the conveying drum 14 is rotated counterclockwise. The image reading unit 2 reads the image surface in the course of the rotation in the direction, and then branches off from the drum surface at a position almost halfway around and is discharged to the sheet discharge table 15. In double-sided reading, the read original is turned upside down, and is again conveyed by the conveying drum 14 to perform backside reading.
[0024]
In the image reading unit 2, a first mirror unit 23 including a light source 23 a and a mirror 23 b sequentially illuminates and reads a passing document at a position directly below the transport drum 14 so as to be orthogonal to the moving direction of the document. The light is reflected by a second mirror unit 24 having a mirror 24a and a mirror 24b arranged at the same position, and forms an image on a linear imaging element 26 via an imaging lens 25 to obtain image information. The image forming apparatus also has a function of placing a document on a stationary document table 27 and moving and reading the mirror units 23 and 24.
[0025]
Image information of the document image read by the image reading unit 2 is subjected to image processing by an image processing device, and is temporarily stored in a memory as image information.
[0026]
In the image forming section 3, the image information is read out from the memory and input to the exposure device 33, and a laser beam modulated according to the image information from a laser light source (not shown) has a photosensitive layer by rotating a polygon mirror. The main scanning exposure is performed on the photosensitive drum 31. The main scanning by the polygon mirror in the axial direction of the photosensitive drum 31 to which the charging potential has been previously applied by the charging device 32 and the sub-scanning by the rotation of the photosensitive drum 31 are performed, and the electrostatic latent image is formed on the photosensitive layer of the photosensitive drum 31. Form an image. Thereafter, the electrostatic latent image is reversely developed by a developer in a developing device 40 to form a toner image, that is, a developed image.
[0027]
In parallel with this, a sheet for forming an image is fed from a manual sheet feeding tray 19 as a sheet feeding device or a main body feeding tray 7 for storing sheets. The main body paper feed tray 7 has, for example, three stages of 7a, 7b, and 7c, and one of the paper feed rollers 51A, 51B, and 51C operates to carry out the paper, and the conveyance roller 55, the registration roller 56, and the conveyance roller The paper is fed to the photosensitive drum 31 and is synchronized with the toner image on the photosensitive drum 31.
[0028]
The photosensitive drum 31 on which the sheet is stuck receives the discharge from the transfer device 35 and the irradiation of light from the charge elimination lamp (TSL) 41, whereby the toner image on the photosensitive drum 31 is moved to the sheet side. The paper on which the toner image has been transferred and transferred is discharged by the separating device 36 and separated from the photosensitive drum 31, and is conveyed to the fixing device 38 via the conveying belt, and has the heater 38 c to be heated by the fixing device 38 c. When the toner passes between the fixing roller 38b and the fixing roller 38a, the toner is fixed by heat, and the toner is fixed. The sheet is discharged from the fixing discharge roller 61 of the discharge unit 6 and discharged to the discharge tray 64. Is done.
[0029]
On the other hand, the image forming apparatus is configured so that the photosensitive drum 31 from which the paper is separated and from which the residual potential has been eliminated is cleaned by a cleaning device 37 to remove the residual toner, and then enters the next image forming process. Is performed by a CPU as a control unit.
[0030]
The image forming apparatus includes a mode (hereinafter, referred to as an “OHP mode”) in which an image is formed on an OHP sheet and a blank sheet is used, and the OHP mode can be selected by the user using the operation unit 101.
[0031]
In the OHP mode, the user sets OHP paper in the manual paper feed tray 19, for example, and stores paper to be used as interleaving paper in the main paper feed tray 7 in advance. When the user selects the OHP mode and starts image formation, the feeding of OHP paper from the manual paper feed tray 19 and the feeding of interleaf paper from the main paper feed tray 7 are alternately performed. Is subjected to image formation.
[0032]
FIG. 2 is a block diagram showing a configuration relating to control in a case where a slip sheet is used when forming an image on an OHP sheet in the first embodiment of the image forming apparatus shown in FIG.
[0033]
As shown in FIG. 2, a high voltage from a high-voltage power supply 100 is supplied to the charging device 32, the transfer device 35, and the separation device 36 shown in FIG. The drive voltage of the device 36 is adjusted. The CPU 102 also adjusts the luminance of the charge removing lamp 41.
[0034]
The user selects and inputs an OHP mode in which an image is formed on an OHP sheet and a blank sheet is used from the operation unit 101. The CPU 102 adjusts the charging potential of the charging device 32, the transfer current of the transfer device 35, the separation current of the separation device 36, and the brightness of the charge removing lamp 41 in response to the input from the operation unit 101.
[0035]
FIG. 3 is a diagram showing a time chart of the control concept in the first embodiment shown in FIG.
[0036]
In the present embodiment, as shown in FIG. 3, various conditions are different between OHP paper and interleaved paper. For example, when the paper, that is, the transfer material is OHP paper, the transfer current in the transfer device 35 is increased, the separation current in the separation device 36 is reduced, the luminance of the discharging lamp 41 is reduced, and the charging potential in the charging device 32 is adjusted. Higher. On the other hand, in the case of interleaf paper, the transfer current in the transfer device 35 is reduced, the separation current in the separation device 36 is increased, the luminance of the charge removing lamp 41 is increased, and the charging potential of the charging device 32 is decreased. I do.
[0037]
Here, an example of a preferable configuration condition of the present embodiment will be described.

Specific examples of the control values of the respective conditions shown in FIG. 3 under the configuration conditions are as follows.
[0038]
Conditional total current for OHP paper: 200 μA
Isolation total current: -170 μA
Static elimination lamp: Turn off charge potential: -750V
Conditional total current at the time of slip sheet: 50 μA
Isolation Total Current: -200 μA
Static elimination lamp: Lighting charge potential: -650V
By doing so, according to the present embodiment, when an image is formed on OHP paper and blank paper is used, separation from the photoconductor is a problem in both cases of OHP paper and paper. There is an effect that it can be performed without.
[0039]
2 and 3, all the conditions of the transfer current in the transfer device 35, the separation current in the separation device 36, the luminance of the charge removing lamp 41, and the charging potential in the charging device 32 are controlled. The invention is not limited to this, and may control any one condition.
[0040]
Next, a case where an image is formed on an index sheet will be described.
[0041]
This image forming apparatus has a sheet width detecting means for detecting a width (length in a direction perpendicular to the sheet feeding direction) of a sheet used for image forming, and forms an image in accordance with a detection result by the sheet width detecting means. The conditions at the time of are controlled.
[0042]
FIG. 4 is a block diagram showing a second embodiment of the image forming apparatus shown in FIG. 1 and showing a configuration related to control when an image is formed on an index sheet.
[0043]
As shown in FIG. 4, the transfer device 35 and the separation device 36 shown in FIG. 1 are supplied with a high voltage from the high-voltage power supply 100, and the transfer device 35 and the transfer device 35 are instructed by the CPU 104 based on the detection result of the paper width detection means 57. And the drive voltage of the separation device 36 is adjusted. The user operates the operation unit 103 to input an image formation instruction.
[0044]
FIGS. 5A and 5B are diagrams showing an example of the sheet width detecting means 57 in the second embodiment shown in FIG. 4, wherein FIG. 5A is a perspective view of the sheet width detecting means 57, and FIG. FIG.
[0045]
5A and 5B, reference numeral 10 denotes an index sheet as an image forming sheet. As shown in FIG. 5A, the index sheet 10 has an ear 10a having a width smaller than other portions. Have. As described above, the width of the index paper 10 changes discontinuously.
[0046]
The sheet width detecting means 57 includes a sheet guide plate 57a for guiding the index sheet 10 to be subjected to the sheet width detection, a slit 57b provided on the sheet guide plate 57a and allowing light to pass therethrough, and a slit 57b of the sheet guide plate 57a. And an LED array 57c for optically detecting the width of the paper passing therethrough, and is provided at a predetermined position in the paper feed path preceding the photosensitive drum 31.
[0047]
The index paper 10 advances along a paper guide plate 57a at a predetermined speed (paper feed linear speed), and when passing over the slit 57, its width (in a direction perpendicular to the paper feed direction) is determined by the LED array 57c. Is detected). As described above, by transporting the index paper 10 at a predetermined speed, the relationship between the position of the index paper 10 in the paper feed direction and the paper width at that position is obtained.
[0048]
In addition, the maximum value of the sheet widths detected in each portion of the index sheet 10 is hereinafter referred to as “maximum sheet passing width”.
[0049]
When the CPU 104 detects a change in the sheet width, the portion of the index sheet 10 where the sheet width changes is transferred based on the distance from the sheet width detecting means 57 to the transfer pole entrance of the transfer device 35 and the sheet feed linear speed. The time to reach the pole is calculated, and control is performed so that the transfer current value is changed in accordance with the timing.
[0050]
Similarly, the time required for the portion of the index paper 10 where the paper width changes to reach the separation pole of the separation device 36 is calculated, and control is performed so as to change the separation current value in accordance with the timing.
[0051]
Here, an example of a preferable configuration condition of the present embodiment will be described.

Under this configuration condition, the transfer current value is preferably obtained and controlled according to Equation 1.
[0052]
(Equation 1)
Transfer current value = (reference transfer current value) + (reference transfer current value) × (0.43X ² −0.76X + 0.33)
In Expression 1, X = (detected sheet passing width) / (maximum sheet passing width), and the reference transfer current value is a transfer current value used when the predetermined sheet width is the maximum sheet passing width.
[0053]
Further, under this configuration condition, the separation current value is preferably obtained and controlled according to Equation 2.
[0054]
(Equation 2)
Separation current value = (reference separation current value) + (reference separation current value) × (0.43X ² −0.76X + 0.33)
In Expression 2, X = (detected sheet passing width) / (maximum sheet passing width), and the reference separation current value is a separation current value used when the predetermined sheet width is the maximum sheet passing width.
[0055]
By performing the above-described control, sufficient transfer and separation capabilities can be exhibited even when an image is formed on the ears 10a of the index paper 10, and deterioration in image quality can be prevented.
[0056]
Next, another example of the sheet width detecting means different from FIGS. 5A and 5B will be described. FIG. 6 shows the sheet width detecting means 57 of the second embodiment shown in FIG. FIGS. 7A and 7B are diagrams illustrating another example different from FIGS. 7A and 7B, and are illustrated here as a sheet width detecting unit 157. 6A is a perspective view of the sheet width detecting unit 157, and FIGS. 6B and 6C are cross-sectional views of the sheet width detecting unit 157.
[0057]
Similar to the examples shown in FIGS. 5A and 5B, reference numeral 10 denotes an index sheet as an image forming sheet. As shown in FIG. 6A, the index sheet 10 is narrower than other portions. It has an ear 10a.
[0058]
The paper width detecting means 157 is provided with a paper guide plate 157a for guiding the index paper 10 to be subjected to the paper width detection, a plurality of slits 157f provided in the paper guide plate 157a, and a slit 157f of the paper guide plate 157a. And a press-down detecting means 157b having a protruding convex portion 157c, and is provided at a predetermined position before the photosensitive drum 31 in the paper feed path.
[0059]
The convex portion 157c of the press detecting means 157b has a structure in which the convex portion 157c is lowered when pressed from above. As shown in FIG. 6B, when the index paper 10 is not provided above the convex portion 157c, The light from the light emitting element 157e is received by the light receiving element 157d, and as shown in FIG. 6C, when the index paper 10 is located above the convex part 157c, the convex part 157c is pushed down, whereby the light emitting element 157e is pressed. Is blocked and does not reach the light receiving element 157d, thereby detecting whether or not the convex portion 157c has been pressed down.
[0060]
As shown in FIG. 6A, a plurality of press detection units 157b are provided in a direction perpendicular to the paper feed direction. In this example, it is possible to detect the paper width based on how many protrusions 157c are pressed down. It has a structure that can be used.
[0061]
Note that the subsequent control in this example is the same as the example described with reference to FIGS. 5A and 5B, and a detailed description thereof will be omitted.
[0062]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an image forming apparatus capable of ensuring image quality and feeding reliability even when OHP paper or index paper is used as image forming paper.
[0063]
That is, according to the present invention, even when a blank slip sheet is used when forming an image on an OHP sheet, it is possible to smoothly separate the OHP sheet and the slip sheet from the photoreceptor. There is an effect that a paper jam can be eliminated.
[0064]
Further, according to the present invention, even when an image is formed on an ear portion narrower than other portions of the index sheet, sufficient transfer and separation ability can be exhibited, and deterioration of image quality can be prevented. Can be.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view illustrating a configuration of an embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a block diagram illustrating a configuration relating to control in a case where an interleaf is used when forming an image on an OHP sheet according to the first embodiment of the image forming apparatus illustrated in FIG. 1;
FIG. 3 is a diagram showing a time chart of a control concept in the first embodiment shown in FIG. 2;
FIG. 4 is a block diagram illustrating a configuration relating to control in a case where an image is formed on an index sheet according to a second embodiment of the image forming apparatus illustrated in FIG. 1;
5A and 5B are diagrams illustrating an example of a sheet width detecting unit in the second embodiment illustrated in FIG. 4, wherein FIG. 5A is a perspective view of the sheet width detecting unit, and FIG. 5B is a cross-sectional view of the sheet width detecting unit; It is.
FIG. 6 is a diagram showing another example of the sheet width detecting means in the second embodiment shown in FIG. 4, which is different from FIGS. 5A and 5B, and FIG. FIGS. 3B and 3C are cross-sectional views of the sheet width detecting means.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 automatic document feeder 11 document feeder 12 feeder roller 13 registration roller 14 transport drum 15 discharger 2 image reader 23a light source 23b mirror 23 first mirror unit 24a mirror 24b mirror 24 second mirror unit 25 imaging lens 26 Image pickup device 27 Still platen 3 Image forming unit 31 Photoconductor drum 32 Charging device 33 Exposure device 40 Developing device 19 Manual paper feed tray 7 Main paper feed trays 7a, 7b, 7c Main paper feed trays 51A, 51B, 51C Paper feed rollers 55 transport roller 56 registration roller 39 transport roller 35 transfer device 41 static elimination lamp (TSL)
36 Separating device 38 Fixing devices 38a, 38b Fixing roller 38c Heater 6 Discharge unit 61 Fixing discharge roller 64 Discharge tray 37 Cleaning device 100 High-voltage power supplies 101, 103 Operating units 102, 104 CPU
10 Index Paper 10a Ear 57 Paper Width Detecting Means 57a Paper Guide Plate 57b Slit 57c LED Array 157 Paper Width Detecting Means 157a Paper Guide Plate 157b Pressing Detecting Means 157c Convex 157d Light Receiving Element 157e Light Emitting Element 157f Slit

Claims (7)

A photoconductor, a charging device that charges the photoconductor, a developing device that converts the electrostatic latent image formed on the photoconductor into a toner image, a transfer device that transfers the toner image by the developing device to a sheet, A separating device that separates the photoconductor from the paper, a static elimination lamp that irradiates the photoconductor before development and before separation, an operation unit that is operated by a user, and an image based on an input from the operation unit. In an electrophotographic image forming apparatus having a control unit for controlling the formation,
The operation unit has mode input means for inputting that the user uses OHP paper as the paper and uses blank interleaving paper when discharging the paper.
When the control unit uses an OHP sheet as the sheet by the mode input unit and inputs that a blank interleaving sheet is used at the time of discharge, the control unit outputs an image on the OHP sheet and discharges the sheet. At the time of discharging a blank sheet inserted between each of the OHP sheets, at least one of a charging potential by the charging device, a transfer current by the transfer device, a separation current by the separation device, and a luminance of the discharge lamp. An image forming apparatus characterized in that one is different. The control unit controls the charging potential when discharging a blank sheet inserted between the OHP sheets so as to be lower than the charging potential when forming an image on the OHP sheet and discharging the sheet. The image forming apparatus according to claim 1, wherein: The control unit controls the transfer current when discharging a blank sheet inserted between each of the OHP sheets to be lower than the transfer current when discharging an image after forming an image on the OHP sheet. The image forming apparatus according to claim 1, wherein: The control unit controls the separation current when discharging a blank sheet inserted between each of the OHP sheets to be higher than the separation current when discharging an image after forming an image on the OHP sheet. The image forming apparatus according to claim 1, wherein: The control unit may be configured such that the brightness of the discharge lamp when discharging a blank sheet inserted between the OHP sheets is higher than the brightness of the discharge lamp when forming an image on the OHP sheet and discharging the sheet. The image forming apparatus according to claim 1, wherein the control is performed such that the brightness is obtained. A photoconductor, a charging device that charges the photoconductor, a developing device that converts the electrostatic latent image formed on the photoconductor into a toner image, a transfer device that transfers the toner image by the developing device to a sheet, An electrophotographic image forming apparatus including a separation device that separates a photoconductor and the paper, an operation unit that is operated by a user, and a control unit that controls image formation based on input from the operation unit. ,
A sheet width detecting unit that detects a length of the sheet in a direction perpendicular to a sheet feeding direction as a sheet width,
The image forming apparatus, wherein the control unit controls a transfer current by the transfer device and a separation current by the separation device based on a detection result by the sheet width detection unit. 7. The image forming apparatus according to claim 6, wherein the sheet has a discontinuous change in the sheet width, and the sheet width detecting unit detects the discontinuous change in the sheet width. apparatus.

Images