JP3556413B2 - Image forming device - Google Patents

Description

【００２２】
表１の結果より明らかなように、本発明による画像形成装置では、φ３０ｍｍ以下の小径の感光体１を用いた場合にも、搬送ガイド板１１’’の転写装置側に設けた傾斜部１４により、転写のためのニップ幅を稼ぐことができるので、低湿環境や両面時でも安定した転写性を得ることができる。
尚、上記の実施例ではワイヤ電極方式の転写装置を用いて説明を行ったが、針状電極等の非接触転写装置を用いた場合にも本発明が有効であることは言うまでもない。
【００２３】
【発明の効果】
以上説明したように、本発明の画像形成装置においては、転写終了後に像担持体表面から転写材自身のコシ及び自重により分離された転写材の先端が搬送ガイド部材または搬送ガイド部材に付設された他の部材に接触した後、該先端部の進行方向が上方に変更されるとともに、転写材が搬送ガイド部材の少なくとも一部で該接触位置よりも高い位置を搬送されるように搬送ガイド部材を構成したことにより、小径（例えばφ３０ｍｍ以下）の像担持体を用いた場合にも、転写のためのニップ幅を稼ぐことができるので、低湿環境や両面時でも安定した転写性を確保することができる。
【００２４】
そして本発明の画像形成装置においては、前記の構成に加えて、搬送ガイド部材の転写材搬送方向上流側である転写装置側に下向きの傾斜部を一体に設けるとともに、転写材先端がこの傾斜部に進入するように配置したことにより、搬送ガイド部材の水平搬送部と進行方向変更部（傾斜部）を一体に形成することができるので、コストダウンを図ることができる。
【００２５】
さらに本発明の画像形成装置においては、前記の構成に加えて、前記傾斜部の転写側自由端から延ばした水平延長線が転写装置のケーシング内部に直接進入することがないように搬送ガイド部材を構成・配置したことにより、転写材が誤って傾斜部の下側に進んでしまった場合でも、転写材が転写装置のケーシング内部に進入することがないため、転写装置の破損を防止することができる。
【図面の簡単な説明】
【図１】本発明の一実施例を示す画像形成装置の概略構成図である。
【図２】図１に示す画像形成装置における転写材搬送動作の説明図である。
【図３】図１に示す画像形成装置における転写材搬送動作の説明図である。
【図４】
本発明の別の実施例を示す画像形成装置の概略構成図である。
【図５】
図４に示す画像形成装置における転写材搬送動作の説明図である。
【図６】
図４に示す画像形成装置における転写材搬送動作の説明図である。
【図７】
本発明の別の実施例を示す画像形成装置の構成及び動作の説明図である。
【図８】
従来の画像形成装置の構成例を示す概略構成図である。
【符号の説明】
１：感光体（像担持体）
２：帯電装置
４：現像装置
５：進入ガイド部材
６：転写材
７：転写装置
７ａ：ケーシング
７ｂ：ワイヤ電極
９：クリーニング装置
１０：除電用露光装置
１１’，１１’’：搬送ガイド板（搬送ガイド部材）
１２：定着装置
１３：マイラ部材
１４：傾斜部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus using an electrophotographic process applied to a copying machine, a facsimile, a printer, and the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an image forming apparatus using an electrophotographic process has been known, and has been commercialized as a copier, a facsimile, a printer, or the like.
FIG. 8 shows a simplified configuration example of an image forming apparatus using an electrophotographic process. In FIG. 8, reference numeral 1 denotes a drum-shaped photoconductor as an image carrier, 2 denotes a charging device, 3 denotes optical image information from a document image exposure device or an optical writing device using laser light, 4 is a developing device, 5 is a transfer material entry guide member, 6 is a transfer material such as transfer paper or an OHP sheet, 7 is a corona transfer device, 8 is a charge removing / separating member using a wire, 9 is a cleaning device, Reference numeral 10 denotes an exposing device for static elimination, 11 denotes a transport guide plate, and 12 denotes a fixing device.
[0003]
8, when the image forming operation is started, the photoconductor 1 is rotated in the direction of the arrow in the figure. After the photoreceptor surface is uniformly charged by the charging device 2, the optical image information 3 is irradiated to form an electrostatic latent image, and the electrostatic latent image is developed by the toner in the developer of the developing device 4. Then, the image is visualized and reaches the transfer area (the opposing portion of the photoconductor 1 and the transfer device 7). On the other hand, a transfer material 6 such as a transfer sheet fed from a sheet feeder (not shown) in synchronization with the above-described latent image forming and developing operations is guided by the entry guide member 5, sent to the transfer area, and The transfer device 7 applies a charge of a polarity opposite to that of the toner to the back surface in a state of being in close contact with the surface of the body 1, and the developed image (toner image) on the photoconductor 1 is transferred to the transfer material 6. After the transfer, the transfer material 6 is removed from the surface of the photoreceptor by removing its charge by the charge removing / separating device 8 and guided to the transport guide plate 11 to reach the fixing device 12, where the heating roller and the pressure of the fixing device 12 are pressed. The toner image is fixed on the transfer material 6 by the roller, and is discharged to a discharge unit (not shown). On the other hand, the photoreceptor 1 after the transfer removes residual toner by the cleaning device 9 and is discharged by the exposure device 10 for discharging. When the image forming operation for one sheet is completed as described above and a large number of images are to be formed, the same operation is repeatedly executed.
[0004]
[Problems to be solved by the invention]
In recent years, image forming apparatuses using an electrophotographic process have been reduced in size and cost, and accordingly, it has been necessary to reduce the size and cost of image carriers such as photoconductors and other units.
For example, in an image forming apparatus having a configuration as shown in FIG. 8, as one method of reducing the size and cost, a method of reducing the diameter of the drum-shaped photoconductor 1 (for example, reducing the diameter φ to 30 mm or less). Is raised. This makes it easier to separate the transfer material by stiffness than with conventional photoconductors, eliminating the need for a static elimination / separation charger that was used for photoconductors with large diameters, and needle-like electrodes for static elimination / separation. Can be used, and miniaturization and cost reduction of the static elimination / separation device can be realized.
[0005]
However, since the diameter of the photoreceptor 1 is reduced and the transfer material 6 is easily separated, it is difficult to obtain a sufficient nip width for the transfer, thereby stabilizing the transferability in the conventional corona discharge method. Becomes difficult.
[0006]
Therefore, in recent years, in order to achieve a reduction in the amount of generated ozone, a roller or belt-type contact type transfer device has come into wide use in an image forming apparatus using a small-diameter drum-shaped photoconductor. However, although the size can be reduced by adopting such a method, the cost is still higher than the corona discharge method at present.
[0007]
The present invention has been made in view of the above circumstances, and an object (problem) of the present invention is to employ a system of “a small-diameter image carrier having a diameter of 30 mm or less + a non-contact transfer device” capable of realizing a reduction in size and cost. In the image forming apparatus described above, a sufficient transfer nip width is secured without obtaining a complicated configuration to obtain stable transferability.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an image carrier having a small diameter (for example, having a diameter φ of 30 mm or less) and a non-contact type transfer device for transferring a developed image formed on the surface thereof to a transfer material. A transfer guide member for guiding and transporting the transfer material separated from the image carrier to the fixing device after the transfer is completed, wherein the transfer material passes through a transfer area to transfer a developed image, and then the image carrier is In an image forming apparatus configured to be separated from the surface by the stiffness of the transfer material itself and its own weight, the end of the transfer material separated from the surface of the image carrier by the stiffness of the transfer material itself and its own weight after the transfer is completed, the transfer guide member or the transfer member After contacting another member attached to the guide member, the advancing direction of the tip is changed upward, and the transfer material is conveyed at a position higher than the contact position by at least a part of the conveyance guide member. To constitute a conveyance guide member so.
[0009]
Further, in the present invention, a downward inclined portion is integrally provided on the transfer device side, which is an upstream side of the transport guide member in the transfer material transport direction, and the transfer material tip is arranged so as to enter the inclined portion .
[0010]
Further, the present invention is characterized in that the transport guide member is configured and arranged so that a horizontal extension line extending from the transfer-side free end of the inclined portion does not directly enter the inside of the casing of the transfer device. You.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the illustrated examples.
[0012]
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing one embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a drum-shaped photoreceptor as an image carrier, 2 denotes a charging device, 3 denotes optical image information from an original image exposure device or an optical writing device using laser light, 4 is a developing device, 5 is a transfer material entry guide member, 6 is a transfer material, 7 is a corona transfer device, 7a is a casing, 7b is a wire electrode, 9 is a cleaning device, 10 is an exposing device for removing electricity, and 11 '. Denotes a plate-shaped conveyance guide member (hereinafter, referred to as a conveyance guide plate), and 12 denotes a fixing device. Units having the same reference numerals as those of the image forming apparatus shown in FIG. In the present embodiment, the diameter φ of the drum-shaped photoreceptor 1 as an image carrier is 30 mm, which is smaller than that of the conventional device. Further, since the diameter of the photoconductor 1 is reduced, a charge removing / separating member is omitted. Further, in this embodiment, a plate-shaped mylar member 13 extending diagonally upward in the transfer material advancing direction is provided on the transfer device side (upstream side in the transfer material transfer direction) of the transfer guide plate 11 '.
[0013]
In FIG. 1, when an image forming operation is started, the photoconductor 1 is rotated in a direction indicated by an arrow in the figure. After the surface of the photoreceptor is uniformly charged by the charging device 2, optical image information 3 is irradiated to form an electrostatic latent image, and the electrostatic latent image is developed by the toner in the developer of the developing device 4. Then, the image is visualized and reaches a transfer region (a discharge region formed by the wire electrode 7b at the opposing portion of the photoconductor 1 and the transfer device 7). On the other hand, a transfer material 6 such as a transfer sheet fed from a sheet feeding device (not shown) in synchronization with the above-described latent image forming and developing operations is guided by the entrance guide member 5 and reaches the surface of the photoconductor 1. The toner is guided by the transfer device 7 to a transfer area which receives a transfer charge having a polarity opposite to that of the toner while being in close contact with the surface of the photoconductor 1. Then, the transfer material 6 passes through the transfer area to transfer the developed image (toner image), and then is separated from the surface of the photoconductor 1 by the stiffness and weight of the transfer material itself. Then, the leading end of the transfer material 6 reaches and contacts the mylar member 13 attached to the transport guide plate 11 'as shown in FIG. 2, and the traveling direction is changed obliquely upward by the mylar member 13. Then, as the leading end of the transfer material 6 passes over the mylar member 13 as shown in FIG. 3, the transfer material 6 is transported to a position higher than the contact position of the leading end.
[0014]
Here, until the leading end of the transfer material 6 reaches the mylar member 13 of the transport guide plate 11 ', the separation point between the transfer material 6 and the photoconductor 1 is near the point A shown in FIG. The separation point changes to the downstream side in the rotation direction of the photoconductor as the tip end of the mylar member 13 rises, and the separation point is near the point B in the state as shown in FIG. In other words, the nip width required for transfer increases as the separation point changes from the vicinity of the point A to the vicinity of the point B. Therefore, even in a low-humidity environment where transferability is reduced or in both surfaces (when images are formed on both surfaces of the transfer material). Stable transferability can be secured.
[0015]
Next, FIG. 4 is a schematic configuration diagram of an image forming apparatus showing another embodiment of the present invention.
In FIG. 4, units denoted by the same reference numerals as in FIG. 1 are the same, and the image forming operation is also the same. Although the mylar member 13 of the transport guide plate shown in FIG. 1 is not provided in the image forming apparatus of this embodiment, the transfer side of the transport guide plate 11 ″ is bent obliquely downward, and Make up.
[0016]
In the image forming apparatus shown in FIG. 4, the transfer material 6 passes through the transfer area to transfer the developed image (toner image) and then transfers from the surface of the photoreceptor 1 to the transfer material itself in the same manner as described above with reference to FIG. Separation by weight and own weight. Then, the leading end of the transfer material 6 separated from the photoreceptor 1 contacts the inclined portion 14 of the transport guide plate 11 '' as shown in FIG. 5, and the traveling direction can be changed upward by the inclined portion 14. Then, the leading end of the transfer material 6 travels upward along the inclined portion 14, and then, as shown in FIG. 6, is transported through the parallel portion of the transport guide plate 11 '' which is higher than the contact position of the leading edge. To the fixing device 12.
[0017]
Also in the case of the present embodiment, the separation point of the transfer material 6 changes from the point A shown in FIG. 5 to the point B shown in FIG. 6 due to the inclined portion 14 of the transport guide plate 11 ″, so that the nip width for transfer increases. However, stable transferability can be ensured even in a low-humidity environment where transferability is reduced or in both surfaces.
[0018]
Next, FIG. 7 is an explanatory diagram of the configuration and operation of an image forming apparatus according to another embodiment of the present invention.
In FIG. 7, the units denoted by the same reference numerals as those in FIG. 4 are the same, and the image forming operation is also the same. However, in this embodiment, the unit is extended from the transfer-side free end of the inclined portion 14 of the transport guide plate 11 ''. The transport guide plate 11 ″ is configured and arranged so that the horizontal extension does not directly enter the inside of the casing 7a of the transfer device 7.
[0019]
That is, as shown in FIG. 7, the inclined portion 14 of the transport guide plate 11 ″ is formed so that an extension (indicated by a broken line in the figure) does not necessarily directly enter the inside of the casing 7 a of the transfer device 7 (casing). 7a is arranged and intersected with the surface on the outlet side of the casing below the end K of the casing 7a. Therefore, when the user uses the transfer material 6 that is out of specification or greatly curled, Even when 6 is accidentally advanced to the lower side of the inclined portion 14, the transfer material 6 does not enter the inside of the casing 7a, so that the position of the wire electrode 7b inside the transfer device 7 is shifted, There is no damage.
[0020]
Here, an experimental result of the solid portion transferability in the image forming apparatus using the transport guide plate 11 ″ having the configuration and arrangement shown in FIG. 7 is shown in FIG. 8 using an image forming apparatus using the conventional type transport guide plate 11 shown in FIG. The results are shown in Table 1 below in comparison with the experimental results of the solid portion transferability in
In this case, the configuration of the image forming apparatus was such that the diameter of the drum-shaped photoconductor 1 was 30 mm, the linear velocity of the photoconductor 1 was 90 mm / sec, and the developing device 4 was a dry two-component developing system. As the transfer material 6, Ricoh Type 6200 paper was used.
The solid part transferability is determined by changing the environment (temperature / humidity) conditions to transfer a solid image to the front surface of the transfer paper, or to the transfer of the back surface when forming a solid image on both sides of the transfer paper. Was tested.
[0021]
[Table 1]

[0022]
As is clear from the results shown in Table 1, in the image forming apparatus according to the present invention, even when the photosensitive member 1 having a small diameter of 30 mm or less is used, the inclined portion 14 provided on the transfer device side of the transport guide plate 11 ″ is used. In addition, since a nip width for transfer can be increased, stable transfer properties can be obtained even in a low-humidity environment or on both sides.
Although the above embodiment has been described using a wire electrode type transfer device, it goes without saying that the present invention is also effective when a non-contact transfer device such as a needle electrode is used.
[0023]
【The invention's effect】
As described above, in the image forming apparatus of the present invention , the end of the transfer material separated from the surface of the image carrier by the stiffness and its own weight of the transfer material after the transfer is completed is attached to the transfer guide member or the transfer guide member. After contacting another member, the traveling direction of the leading end is changed upward, and the transfer guide member is moved so that the transfer material is conveyed at a position higher than the contact position by at least a part of the transfer guide member. With this configuration, even when an image carrier having a small diameter (for example, φ30 mm or less) is used, the nip width for transfer can be increased, so that stable transferability can be ensured even in a low-humidity environment or on both sides. it can.
[0024]
In the image forming apparatus of the present invention , in addition to the above configuration, a downward inclined portion is integrally provided on the transfer device side, which is an upstream side of the transport guide member in the transfer material transport direction, and the tip of the transfer material is formed by the inclined portion. by arranging such that enters, since the traveling direction changing unit horizontal conveying portion of the conveyance guide member (inclined portion) can be formed integrally, the cost can be reduced.
[0025]
Further, in the image forming apparatus of the present invention, in addition to the above, the conveyance guide member so as not to horizontal extension line extended from the transfer-side free end of the inclined portion enters directly into the casing inside of the transfer device With the configuration and arrangement, even if the transfer material accidentally advances to the lower side of the inclined portion, the transfer material does not enter the inside of the casing of the transfer device, thereby preventing damage to the transfer device. it can.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing one embodiment of the present invention.
FIG. 2 is an explanatory diagram of a transfer material transport operation in the image forming apparatus shown in FIG.
FIG. 3 is an explanatory diagram of a transfer material transport operation in the image forming apparatus shown in FIG. 1;
FIG. 4
FIG. 9 is a schematic configuration diagram of an image forming apparatus showing another embodiment of the present invention.
FIG. 5
FIG. 5 is an explanatory diagram of a transfer material transport operation in the image forming apparatus shown in FIG. 4.
FIG. 6
FIG. 5 is an explanatory diagram of a transfer material transport operation in the image forming apparatus shown in FIG. 4.
FIG. 7
FIG. 7 is an explanatory diagram of a configuration and operation of an image forming apparatus according to another embodiment of the present invention.
FIG. 8
FIG. 9 is a schematic configuration diagram illustrating a configuration example of a conventional image forming apparatus.
[Explanation of symbols]
1: Photoconductor (image carrier)
2: Charging device 4: Developing device 5: Entry guide member 6: Transfer material 7: Transfer device 7a: Casing 7b: Wire electrode 9: Cleaning device 10: Exposure devices 11 ', 11''for static elimination: Transport guide plate (Convey Guide member)
12: fixing device 13: mylar member 14: inclined portion

Claims (1)

A small-diameter image carrier, a non-contact transfer device for transferring a developed image formed on the surface of the image carrier to a transfer material, and a transfer device separated from the image carrier after transfer is guided and transported to a fixing device. The transfer material passes through a transfer area to transfer a developed image, and then is separated from the surface of the image carrier by the stiffness and weight of the transfer material itself. ,
After the end of the transfer, the tip of the transfer material separated from the surface of the image carrier by the stiffness of the transfer material itself and its own weight comes into contact with the transport guide member or another member attached to the transport guide member, and then the traveling direction of the tip portion is changed. The transfer guide member is configured so that the transfer material is conveyed at a position higher than the contact position in at least a part of the transfer guide member while being changed upward, and the transfer guide member is disposed upstream of the transfer guide member in the transfer material transfer direction. A downward inclined portion is integrally provided on a certain transfer device side, the leading end of the transfer material is arranged so as to enter the inclined portion, and a horizontal extension line extending from the free end of the inclined portion on the transfer side is inside the casing of the transfer device. An image forming apparatus , wherein a transport guide member is configured and arranged so as not to directly enter the image forming apparatus.

Images