JP3661841B2 - Image processing method of image forming apparatus - Google Patents

Description

【００３６】
また、上記実施例においては、この発明の像担持体として感光体ドラムを用いた場合を説明したが、次にその変形例として像担持体に中間転写ベルトを用いる場合について説明する。この場合には、図５に示すように、転写ローラ６２に対向して図２の感光体ドラム４８の代わりに中間転写ベルトＶを支持する支持ローラ１４８が設置される。支持ローラ１４８の両端部には円周に沿って凹部（段差）１４８ａ，１４８ｂが設けられている。その他の構成は図２、図３に示す構成と同等である。
中間転写ベルトＶは、その表面に感光体（図示しない）から転写されたトナー像を担持しながら支持ローラ１４８に密着して搬送され、中間転写ベルトＶと転写ローラ６２との間に挿入される用紙Ｐにトナー像が転写される。
【００３７】
この転写工程は、前述の実施例と同様に行われる。従って中間転写ベルトＶと転写ローラ６２とのギャップも前述の実施例と同様に用紙の厚さに応じてソレノイド６９のオン・オフによって設定される。この変形例も、表１に示す性能と同等の性能を示すことが確認された。
また、転写ローラ６２のクリーニングについても、前述の実施例と同様に行うことができる。
【００３８】
【発明の効果】
この発明によれば、用紙が薄い程、像担持体と転写部材とのギャップが広くなるように設定されるので、用紙が薄い場合には像担持体からの剥離が容易となりジャムの発生が防止でき、用紙が厚い場合には転写ズレが防止できる。
【図面の簡単な説明】
【図１】この発明の実施例の全体構成図である。
【図２】実施例の要部の拡大側面図である。
【図３】実施例の要部の拡大側面図である。
【図４】実施例の主要動作を示すフローチャートである。
【図５】この発明の変形例を示す図２対応図である。
【符号の説明】
３０ 本体
３１ 原稿読取りユニット
３２ 作像ユニット
３５ 原稿台
３６ 自動原稿搬送装置
４０ スキャナ
４０ａ 走査ユニット
４１ ランプリフレクターアセンブリ
４２ａ 反射ミラー
４２ｂ 反射ミラー
４２ｃ 反射ミラー
４４ ＣＣＤ
４６ レーザー書込みユニット
４７ 現像器
４８ 感光体ドラム
４９ 定着ユニット
５０ 給紙部
５１ 用紙カセット
５２ 用紙カセット
５３ 用紙カセット
５４ 手差トレイ
５５ 両面ユニット
５６ スイッチバック路
６０ 昇降トレイ
６１ 帯電器
６２ 転写ローラ
６３ クリーニング器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing method for an image forming apparatus, and more particularly to an image processing method for transferring a toner image on an image carrier onto a recording sheet.
[0002]
[Prior art]
Conventionally, in an electrophotographic image forming apparatus, an electrostatic latent image formed on an image carrier is developed with a developer to form a toner image corresponding to the electrostatic latent image, and then the toner is transferred to a recording sheet and fixed. The toner is fused and fixed on the recording paper by the means to produce a printed matter. In this image forming process, a transfer process for transferring a toner image onto a recording sheet is generally performed by installing a transfer unit using a corona charger on the back side of the recording sheet. In place of the corona charger system that generates ozone for the purpose of environmental protection or the like, a transfer roller system that does not generate ozone is often used. The transfer roller method is a method in which a toner image on an image carrier is transferred to a recording paper by pressing a recording paper against the image carrier with a transfer roller and applying a high voltage to the transfer roller.
[0003]
[Problems to be solved by the invention]
By the way, in the transfer roller system, the recording roller is pressed against the image carrier by the transfer roller, and a high voltage is applied from the back side of the recording paper. Therefore, when the recording paper is weak like a thin paper, recording is performed from the image carrier by electrostatic force. A phenomenon in which the paper is difficult to peel off occurs, and conveyance jam is likely to occur.
[0004]
In order to solve this problem, there is a method of providing a gap between the image carrier and the transfer roller. However, if the gap is widened, this time, when the recording paper is thick paper, due to the strength of the thick paper, the conveyance unevenness etc. It will be directly affected and transfer deviation will occur.
[0005]
The present invention has been made in consideration of such circumstances, and by increasing the distance (gap) between the transfer member and the image carrier as the thickness of the sheet becomes thinner, a conveyance jam can be applied to a thin sheet. The present invention provides an image processing method for an image forming apparatus that suppresses the occurrence of image transfer and that does not cause a transfer deviation with respect to a thick sheet.
[0006]
[Means for Solving the Problems]
The present invention relates to an image forming apparatus having a transfer unit that adjusts a gap between an image carrier and a transfer member according to the thickness of a recording sheet. The thinner the recording sheet, the wider the gap and the recording sheet is thicker than a predetermined thickness. In this case, an image processing method for an image forming apparatus is provided in which the gap is narrower than the thickness of the paper .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The image forming apparatus targeted by the present invention may be any apparatus that forms a toner image on an image carrier such as an electrophotographic copying machine or a laser printer and transfers the toner image onto a recording sheet. The image bearing member of the present invention may be a drum-shaped or belt-shaped photosensitive member, or may be a drum-shaped or belt-shaped intermediate transfer member interposed between the photosensitive member and a sheet. The transfer member can be constituted by a transfer charger or a transfer roller.
[0008]
In the present invention, when the recording paper is thinner than a predetermined thickness, the gap may be set wider than the thickness of the paper. Accordingly, when the recording paper is thin, no pressing force is generated on the image carrier, so that the recording paper can be prevented from being firmly adsorbed to the image carrier, and the occurrence of a conveyance jam due to a peeling error can be prevented.
[0009]
Further, when the recording paper is thicker than a predetermined thickness, the gap may be set narrower than the thickness of the paper. As a result, when the paper is thick, it can be held between the image carrier and the transfer member, and the occurrence of transfer deviation can be prevented.
[0010]
In the present invention, the gap can be set by the step formed on the surface of the image carrier and the positioning member that contacts the image carrier formed at both ends of the transfer member, and the gap is adjusted by moving the transfer member in the axial direction. It may be.
Thus, the gap between the image carrier and the transfer member can be set with high accuracy, and the gap can be adjusted with a simple mechanism.
[0011]
When adjusting the gap, it is preferable to slide the transfer member in the axial direction while rotating the image carrier. Thus, the transfer member can be smoothly slid and the gap can be easily adjusted.
[0012]
When cleaning the transfer member, it is preferable to use reverse bias cleaning and to narrow the gap between the image carrier and the transfer member. This makes it possible to reduce the distance between the transfer member and the image carrier in reverse bias cleaning, that is, when cleaning is performed by returning the toner adhering to the transfer member to the image carrier, and the effect of bias cleaning is sufficient. Good cleaning is possible.
[0013]
The transfer member is preferably composed of a transfer roller. As a result, when the transfer member is a transfer roller, when a sheet thicker than the gap is transferred and conveyed, it is possible to smoothly convey the sheet while appropriately pressing the sheet.
[0014]
【Example】
Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. This does not limit the invention.
FIG. 1 shows an overall configuration diagram of a digital copying machine as an embodiment of the present invention. In the digital copying machine main body 30, an automatic document feeder 36 is provided on a document table 35 made of transparent glass. The automatic document feeder 36 is a device that automatically feeds a plurality of documents set on a document setting tray one by one onto the document table 35.
[0015]
Below the document table 35 is a document reading unit 31 in which a scanner 40 is disposed. The scanner 40 scans and reads an image of a document placed on the document table 35. The scanner 40 exposes the surface of the document, and a reflected light image from the document is input to a CCD 44 which is a photoelectric conversion element. A first scanning unit 40a including a first reflection mirror 42a that reflects reflected light from a document to be guided, and second and third reflected light images from the first reflection mirror 42a to the CCD 44. Second scanning unit 40b having reflection mirrors 42b and 42c mounted thereon, optical lens 43 for forming an image of reflected light from the document on CCD 44 via reflection mirrors 42a to 42c, and reflected light from the document It comprises a CCD 44 that converts an image into an electrical image signal.
[0016]
The scanner 40 reads an image of a document automatically conveyed by the automatic document conveyance device 36 at a predetermined exposure position by an operation related to the automatic document conveyance device 36.
[0017]
The document image read by the scanner 40 is sent to an image data input unit (not shown) as image data, and after predetermined image processing is performed on the image data, it is temporarily stored in the memory of the image processing unit. In response to the output instruction, the image in the memory is read and transferred to the laser writing unit 46.
[0018]
The laser writing unit 46 includes a semiconductor laser light source that emits laser light in accordance with image data read from a memory or image data transferred from an external device, a polygon mirror that deflects the laser light at a constant angular velocity, and a deflection at a constant angular velocity. An f-θ lens for correcting the laser beam so that the laser beam is deflected at a constant angular velocity on the photosensitive drum 48 provided in the image forming unit 32 is provided.
[0019]
The image forming unit 32 supplies toner to the electrostatic latent image formed on the photosensitive drum 48 and the charger 61 that uniformly charges the photosensitive drum 48 to a predetermined potential around the photosensitive drum 48. A developing unit 47 that visualizes the image, a transfer roller 62 that transfers the toner image formed on the surface of the photosensitive drum 48 onto the recording paper, and a cleaning unit 63 that collects excess toner.
[0020]
The original image read by the scanner 40 is temporarily stored in the image memory, read out, and formed as an electrostatic latent image on the surface of the photosensitive drum 48 by scanning the laser beam by the laser writing unit 46, and developed. The toner image is visualized by the toner in the container and becomes a toner image. The toner image is electrostatically transferred onto the recording paper by the transfer roller 62 and then sent to the fixing unit 49.
[0021]
On the discharge side of the image forming unit 32, in addition to the fixing unit 49, a switchback path 56 that reverses the front and rear of the recording paper in order to form an image again on the back surface of the recording paper, A post-processing device 34 that performs stapling processing and the like and includes an elevating tray 60 is provided. The recording paper on which the toner image is fixed by the fixing unit 49 is guided to the post-processing device 34 by the paper discharge roller 57 through the switchback path 56 as necessary, and is subjected to predetermined post-processing. After that, it is discharged.
[0022]
The paper feed unit 50 is disposed below the image forming unit 32, and includes a manual feed tray 54, a duplex unit 55, a multi-stage paper feed tray unit including paper cassettes 51, 52, 53, and these 51, 52, Conveying means for conveying the paper fed from 53 and 54 to the transfer position where the transfer roller in the image forming unit 32 is arranged is provided. The duplex unit 55 communicates with a switchback path 56 that reverses the recording paper, and is used when image formation is performed on both sides of the recording paper.
[0023]
FIG. 2 is an enlarged side view of the photosensitive drum 48 and the transfer roller 62 of FIG. In the figure, concave portions (steps) 48 a and 48 b are provided along the circumference at both ends of the photosensitive drum 48. The transfer roller 62 includes collars 62a and 62b having outer diameters larger than those of the transfer roller 62 at both ends, and a through shaft 62c at the center. Both ends of the shaft 62c are rotatably supported by bearing guides 65a and 65b via bearings 64a and 64b, respectively. The bearing guides 65a and 65b are supported on a support member 67 via compression springs 66a and 66b, respectively, and the support member 67 can reciprocate in the axial direction of the shaft 62c (arrows A and B directions) by a sliding mechanism (not shown). It is supported by. One end of the support member 67 is provided with a tension spring 68 for urging in the direction of arrow A, and the other end is provided with a solenoid 69.
[0024]
When the solenoid 69 is activated (on), the outer circumferences of the collars 62a and 62b are fitted into the recesses 48a and 48b as shown in FIG.
When the solenoid 69 is not operated (off), the support member 67 is moved in the direction of arrow A by the urging force of the tension spring 68 as shown in FIG. 3, and the collars 62a and 62b are pulled out from the recesses 48a and 48b. Thus, the outer periphery thereof is in contact with the outer periphery of the photosensitive drum 48.
When the solenoid 69 is turned on and off, the gap between the photosensitive drum 48 and the transfer roller 62 is 100 μm and 500 μm, respectively.
[0025]
Here, the transfer roller 62 is made of a conductive elastic member such as EPDM or urethane rubber, and has an outer diameter of 10 to 20 mm, a hardness of 30 to 50 degrees (Asker C), and a volume resistivity. It is.
[0026]
Both the collars 62a and 62b are made of an insulating material (for example, POM).
The compression springs 66a and 66b, the bearing guides 65a and 65b, the bearings 64a and 64b, and the shaft 62c are all conductive, and the voltage is applied to the transfer roller 62 when the compression springs 66a and 66b and the bearing guides 65a and 65b are applied. The bearings 64a and 64b and the shaft 62c are used.
[0027]
The operation in such a configuration will be described with reference to the flowchart shown in FIG. First, when the copying (process) operation of the copying machine shown in FIG. 1 is started in step S1, it is determined whether or not the “thick paper mode” is set (step S2). Here, the thick paper mode is a mode set by the operator when the paper has a thickness of 150 μm or more. In the thick paper mode, the solenoid 69 shown in FIG. 2 is turned on, and the collars 62a and 62b are fitted into the recesses 48a and 48b as shown in FIG. 2, and the interval between the photosensitive drum 48 and the transfer roller is set. (Gap) is set to 100 μm.
[0028]
Next, when the image forming process proceeds (step S5) and a toner image is formed on the photosensitive drum 48, the toner image on the photosensitive drum 48 is transferred to the paper P. At this time, as shown in FIG. 2, the sheet P has a thickness of 150 μm or more, which is thicker than the gap. Therefore, the transfer roller 62 applies a force of about 500 g to the photosensitive drum from the urging force of the compression springs 66a and 66b. It rotates while being pressed against 48. At this time, a high voltage of about +1 kV is applied to the transfer roller 62. The sheet on which the transfer has been completed is fixed and then discharged.
[0029]
On the other hand, in step S7, it is determined again whether or not the solenoid 69 is turned on. If it is turned on, that is, if the transfer roller 62 is close to the photosensitive drum 48, about -1 kV is supplied to the transfer roller 62. Is applied (that is, the transfer roller 62 is reverse-biased). As a result, the transfer roller 62 can be satisfactorily cleaned.
[0030]
When the cleaning of the transfer roller 62 is completed after a predetermined time, the solenoid 69 is turned off (step 10), and the image forming process for one sheet is completed (step 11).
[0031]
If the “thick paper mode” is not set in step S2, that is, if the paper P is a thin paper having a thickness of less than 150 μm, the solenoid 69 is turned off in step S4. Thereby, as shown in FIG. 3, the outer circumferences of the collars 62 a and 62 b are in contact with the outer circumference of the photosensitive drum 48. At this time, the gap between the photosensitive drum 48 and the transfer roller 62 is set to 500 μm.
Accordingly, in step S6, the paper P is smoothly conveyed without being pressed against the photosensitive drum 48 by the transfer roller 62, and is transferred.
During this transfer, a high voltage of about +1 kV is applied to the transfer roller 62 as described above.
[0032]
In step S7, if the solenoid 69 is turned off, that is, if the transfer roller is separated from the photosensitive drum 48, the solenoid 69 is turned on, and then the transfer roller 62 is approximately −as described above. The transfer roller 62 is cleaned by applying a high voltage of 1 kV (step S9). Thereafter, operations in steps S10 and S11 are performed.
[0033]
In the above operation, when the transfer roller 62 is moved in the direction of arrow A or B by turning on / off the solenoid 69, it is performed while the photosensitive drum 48 is rotating. As a result, the collars 62a and 62b smoothly enter and exit the recesses 48a and 48b.
[0034]
Table 1 shows the results of performance tests on peelability and transfer displacement using thin paper of 100 μm thickness and thick paper of 200 μm thickness in this example. In Table 1, o indicates good and x indicates failure. According to Table 1, if the gap between the photosensitive drum 48 and the transfer roller 62 is set to 100 μm for thick paper and the gap is set to 500 μm for thin paper, the peelability is good. It can be seen that there is no transfer misalignment.
[0035]
[Table 1]

[0036]
In the above embodiment, the case where the photosensitive drum is used as the image carrier of the present invention has been described. Next, as a modified example, the case where an intermediate transfer belt is used as the image carrier will be described. In this case, as shown in FIG. 5, a support roller 148 for supporting the intermediate transfer belt V is installed instead of the photosensitive drum 48 of FIG. Concave portions (steps) 148 a and 148 b are provided along the circumference at both ends of the support roller 148. Other configurations are the same as those shown in FIGS.
The intermediate transfer belt V is conveyed in close contact with the support roller 148 while carrying a toner image transferred from a photoreceptor (not shown) on the surface thereof, and is inserted between the intermediate transfer belt V and the transfer roller 62. The toner image is transferred onto the paper P.
[0037]
This transfer step is performed in the same manner as in the above-described embodiment. Accordingly, the gap between the intermediate transfer belt V and the transfer roller 62 is also set by turning on / off the solenoid 69 according to the thickness of the sheet, as in the above-described embodiment. It was confirmed that this modified example also showed performance equivalent to the performance shown in Table 1.
Also, the transfer roller 62 can be cleaned in the same manner as in the previous embodiment.
[0038]
【The invention's effect】
According to the present invention, the thinner the paper, the wider the gap between the image carrier and the transfer member. Therefore, when the paper is thin, peeling from the image carrier is facilitated and jamming is prevented. In addition, transfer deviation can be prevented when the paper is thick.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an embodiment of the present invention.
FIG. 2 is an enlarged side view of a main part of the embodiment.
FIG. 3 is an enlarged side view of a main part of the embodiment.
FIG. 4 is a flowchart showing a main operation of the embodiment.
FIG. 5 is a view corresponding to FIG. 2 showing a modification of the present invention.
[Explanation of symbols]
30 Main body 31 Document reading unit 32 Image forming unit 35 Document table 36 Automatic document feeder 40 Scanner 40a Scan unit 41 Lamp reflector assembly 42a Reflecting mirror 42b Reflecting mirror 42c Reflecting mirror 44 CCD
46 Laser writing unit 47 Developer 48 Photosensitive drum 49 Fixing unit 50 Paper feed unit 51 Paper cassette 52 Paper cassette 53 Paper cassette 54 Manual feed tray 55 Duplex unit 56 Switchback path 60 Lift tray 61 Charging device 62 Transfer roller 63 Cleaning device

Claims (6)

In an image forming apparatus having a transfer unit that adjusts the gap between the image carrier and the transfer member according to the thickness of the recording paper, the thinner the recording paper, the wider the gap, and if the recording paper is thicker than the predetermined thickness, An image processing method for an image forming apparatus, wherein the gap is narrower than the thickness of the image forming apparatus.   2. The image processing method for an image forming apparatus according to claim 1, wherein when the recording sheet is thinner than a predetermined thickness, the gap is made wider than the thickness of the sheet. The gap can be set by a step formed on the surface of the image carrier and a positioning member that contacts the image carrier formed at both ends of the transfer member, and the gap is adjusted by moving the transfer member in the axial direction. the image processing method of an image forming apparatus according to any one of claims 1-2 to. 4. The image processing method for an image forming apparatus according to claim 3, wherein when adjusting the gap, the transfer member is slid in the axial direction while rotating the image carrier. When the cleaning of the transfer member, and a reverse bias cleaning, and, in the image forming apparatus according to any one of claims 1-4, characterized in that narrowing the gap between the transfer member and the image bearing member Image processing method. The image processing method of the transfer member is an image forming apparatus according to any one of claims 1-5, characterized in that the transfer roller.

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