JPH08248708A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] An image forming apparatus that prevents foreign matter from mixing in recycled toner to prevent abnormal images such as white lines and granular background stains, and improves the durability of the device. I will provide a. In an image forming apparatus 100 including a process cartridge 14 having a toner recycling mechanism 8 for conveying the toner collected to a developing means 4 for reusing the toner remaining on the photoreceptor 1, a transfer paper P is fed from a front surface 100A of the apparatus. The replenishing paper feed cassette 17 is of the front loading type, and the size of the mesh is larger than the gap L between the developing roller 4a and the doctor blade 10 of the developing unit of the dry two-component developing system in the toner conveying path 8D of the toner recycling mechanism. A small filter 26 is provided, the charging unit 2 and the transfer unit 5 are of a bias roller type, and the removing member 30 is provided in sliding contact with the registration roller 20 that conveys the transfer paper P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic process such as a copying machine and a facsimile.

[0002]

2. Description of the Related Art In JP-A-63-267985 and JP-A-63-267986, a toner regulating gap is provided between a rotating magnet roll and a non-magnetic sleeve arranged on the outer circumference of the magnet roll. And a blade member that forms the toner regulation gap, and the substantial toner regulation width of the toner regulation gap is made narrower than the toner regulation width in the developing unit to divide the toner agglomeration or the cut edge of the transfer paper. In Japanese Utility Model Publication No. 63-194367,
A toner recovery device provided with a filter for removing impurities contained in residual toner on a photoconductor is described.

[0003]

Problems to be Solved by the Invention JP-A-63-2679
In Japanese Patent Application Laid-Open No. 85-85679 and Japanese Patent Application Laid-Open No. 63-26798619, a cartridge in which a non-magnetic sleeve, a blade, and a case are detachable from a magnet roll is used, and a width of a toner regulation gap is larger than that of a toner regulation gap in a developing section. Since it is narrow, it is possible to collect only reusable toner, but there is a problem in that the size of the device is increased. Actual Kaisho 63-1943
As disclosed in Japanese Patent Publication No. 67, when a filter portion for removing impurities contained in the residual toner on the photoconductor is provided, the impurities may clog the filter portion when the device is used for a long period of time. The parts must be replaceable. However, there is a risk that the toner accumulated in the filter portion may soil the hands as the filter portion is replaced, and it is not suitable for maintenance-free maintenance of process cartridges or replacement by the user.

Further, conventionally, there is one in which a removing member such as a scraping mylar for removing foreign matter adhering to a registration roller which is a paper feeding roller is provided, but the removed foreign matter is accumulated on the removing member. Due to the air flow inside the device,
Although it is a small amount, it may float and adhere to the photoconductor and mix with the waste toner to cause abnormal images such as white lines and granular background stains. Further, a process in which a series of devices for forming a toner image are integrally provided, having a toner recycling mechanism that conveys the residual toner on the photoconductor removed by the cleaning member to the developing unit for reuse. If the cartridge is equipped with a filter that removes impurities in the residual toner and a removal member such as scraping mylar, the process cartridge itself should be replaced earlier if there is clogging in the filter or dirt on the background due to floating toner. This is a problem in terms of performance, device durability, and cost. The main object of the present invention is to prevent the mixing of foreign matter into recycled toner, prevent abnormal images such as white lines and granular background stains, and to improve the durability of the image forming apparatus. To provide.

[0005]

Therefore, according to the first aspect of the invention, the amount of foreign matter contained in the recycled toner is reduced, and the occurrence of white streaks due to granular background stains or clogging of foreign matter in the toner regulation gap in the developing section. In order to prevent such abnormal images, an image forming apparatus including a process cartridge having a toner recycling mechanism is provided with a front loading type sheet feeding means for replenishing transfer sheets from the front of the apparatus. According to the second aspect of the present invention, in order to prevent abnormal images such as white lines due to foreign matter clogging in the gap, a foreign matter mixed in the toner recycling path that is larger than the toner regulation gap in the developing unit is captured. A mesh-like foreign matter removing member having a mesh size smaller than the toner regulation gap was provided in the toner recycling path. According to the third aspect of the present invention, the air flow by the fan for ozone discharge is weakened, and the floating substances such as dust and dust and the scattering of toner are suppressed,
In order to prevent mixing into recycled toner through a photoconductor or the like, a bias roller is adopted in at least one of the charging means and the transfer means for transferring the toner image onto the transfer paper in order to suppress the generation of ozone. According to the fourth aspect of the present invention, the foreign matter is prevented from being mixed into the recycled toner through the photoconductor, and the removed foreign matter is prevented from floating by weakening the air flow by the fan for discharging the ozone to prevent the foreign matter from floating. A removing member is provided to remove foreign matter adhering to the conveyed sheet feeding roller.

[0006]

According to the first aspect of the present invention, the sheet feeding means of the image forming apparatus having the process cartridge having the toner recycling mechanism is of the front loading type in which the transfer sheet is replenished from the front side of the apparatus. It is housed inside and foreign matter such as dust and dust is less likely to adhere to the transfer paper surface.

According to the second aspect of the invention, the developing roller of the developing means using the dry two-component developing system and the regulating member for regulating the toner amount on the developing roller are provided in the toner conveying path of the toner recycling mechanism. Since the mesh-like foreign matter removing member having a mesh size smaller than the gap is provided, the foreign matter larger than the gap contained in the recycled toner is captured by the foreign matter removing member, and the entry into the gap is prevented.

According to the third aspect of the present invention, by using the transfer bias method for at least one of the charging means for charging the photoconductor and the transfer means for transferring the toner image onto the transfer paper, the corona discharge method is used. The amount of ozone generated is suppressed as compared with the charging means and the transfer means, and the air flow in the apparatus is weakened.

According to the fourth aspect of the present invention, at least one of the charging means and the transfer means is of the bias roller type, and the removing member for removing the foreign matter adhering to the paper feed roller is provided. As the foreign matter is removed, the air flow in the device can be weakened, and the removed foreign matter is less likely to scatter.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. An image forming apparatus denoted by reference numeral 100 in FIG. 1 includes therein a well-known exposure scanning unit 101, an image forming unit 102,
A sheet storage unit 103 is provided. The paper storage unit 103 stores a plurality of paper feed cassettes 17 as paper feeding means arranged below the image forming unit 102. Transfer sheets P of different sizes are stacked in each of the paper feed cassettes 17 and are slidable in the vertical direction with respect to the paper surface of FIG. 1, and the front loading system is detachable from the front surface 100A of the apparatus. Has been adopted. Each of the sheet feeding cassettes 17 stores the loaded transfer sheets P inside the apparatus 100.

In the vicinity of each paper feed cassette 17, a paper transport path 104 for communicating the transfer paper P in the cassette with the image forming unit 102.
A sheet feeding roller 19 for feeding the sheets one by one is provided. In the paper transport path 104, a plurality of transport roller pairs 1
8 is arranged so as to reverse the fed transfer paper P and convey it to a registration roller pair 20 as a paper feed roller provided in the image forming unit 102.

In the image forming unit 102, a well-known quenching lamp 7 and a process cartridge 1 as a charge removing means.
4. A transfer roller 5 as a transfer unit and a transfer image fixing unit 16 are arranged. The exposure scanning unit 101 located above the apparatus 100 is provided with a fan 110 for ventilating and cooling the inside of the apparatus, and generates an airflow inside the apparatus 100.

As shown in FIG. 2, the process cartridge 14 has a drum-shaped photosensitive member 1 rotatably driven by a driving roller (not shown) in a case 14A which can be divided into two parts, and a charging means capable of contacting and separating from the photosensitive member 1. The charging roller 2, the developing device 4 as a developing unit, the cleaning device 6 as a cleaning unit, and the toner recycling mechanism 8 are housed, and can be attached to and detached from the apparatus 100 in a vertical direction (paper surface direction). ing.

The surface of the photoconductor 1 is neutralized by the static elimination light 7A from the quenching lamp 7, and the surface potential is 0 to 0.
It is designed to be averaged to a reference potential in the range up to -150v. The charging roller 2 is rotatably supported by the roller case 21 and is applied with a predetermined voltage or current. The contact between the roller 2 and the surface of the photoconductor 1 sets the surface potential of the photoconductor 1 to around −1100 v. There is. The roller case 21 is in contact with one end 22a of a swing lever 22 which is swingably supported, and the contact / separation cam 23 arranged on the other end 22b side of the lever moves the charging roller 2 to a photosensitive member. It is designed to come into pressure contact with one surface. The swing lever 22 is biased by a tension spring (not shown) in a direction to separate the charging roller 2 from the photoconductor 1. Above the charging roller 2, a cleaning pad 24 that contacts the charging roller 2 for cleaning is arranged.

The surface of the photosensitive member 1 between the charging roller 2 and the developing device 4 is irradiated with exposure light 3 from a well-known exposure optical system 109 provided in the exposure scanning unit 101 shown in FIG. The surface potential of the irradiated part is 0 to -29.
An image portion of about 0v is formed.

The developing device 4 has a developing roller 4a to which a charging bias of about -800v is applied and a toner charged by the roller 4a. When the image portion comes onto the developing roller 4a, the toner is imaged. It is designed to be electrostatically attached to the part. As shown in FIGS. 2 and 3, a doctor blade 10 is disposed near the developing roller 4a to regulate the amount of toner on the developing roller 4a and to keep the amount of toner flowing into the photoconductor 1 constant. This doctor blade 1
As shown in FIG. 4, a constant gap L is formed between 0 and the developing roller 4a.

A transfer sheet P is conveyed by a pair of registration rollers 20 to a transfer section A formed between the transfer roller 5 arranged on the side opposite to the charging roller 2 and the photosensitive member 1. As shown in FIG. 5, the registration roller pair 20 includes a driving roller 20 a located below and a driven roller 20 located above.
b, the transfer sheet P conveyed by the pair of conveying rollers 18 is placed in the standby state, and the transfer sheet P in the standby state is formed.
Is conveyed at the transfer portion A at the timing when the front end of the toner image on the photoconductor 1 and the front end of the paper coincide with each other. In this embodiment, the drive roller 20a is driven to rotate counterclockwise, and the driven roller 20b is driven in the clockwise direction to convey the transfer sheet P to the transfer portion A located in the arrow B direction. The driven roller 20b is rotatably supported by a bracket 29 fixed inside the apparatus 100. The bracket 29 is provided with a blade member 30 as a removing member that removes foreign matter such as paper dust attached to the driven roller 20b. The bracket 29 is arranged on the right side of the paper, which is upstream of the registration roller pair 20 in the paper conveyance direction indicated by the arrow B. The blade member 30 is
The driven roller 20b is fixed to the upper surface 29a of the bracket 29 so as to come into sliding contact with the driven roller 20b.
When b rotates, the foreign matter X is deposited on the blade member 30.

The transfer roller 5 shown in FIGS. 1 and 2 is provided with a transfer bias such that the toner image formed on the photosensitive member 1 is electrostatically attracted to the transfer paper P at the transfer portion A. . The toner image is transferred to the transfer sheet P by the transfer sheet P being conveyed to the transfer section A. The transfer paper P that has completed this transfer is conveyed between the heating roller 16a and the pad roller 16b that form the fixing unit 16, and the toner image is welded and fixed by heat and pressure, and then placed outside the apparatus. The sheet is discharged onto the sheet discharge tray 105.

In the vicinity of the fixing unit 16, the transfer paper P, which has been subjected to the one-sided transfer during double-sided copying, is introduced and connected to the paper transport path 104, and the transfer paper P waiting section 107.
Also, a re-feeding roller 108 is arranged.

The toner remaining on the surface of the photosensitive member 1 is as shown in FIG.
The cleaning blade 6a fixed to a holder 6b provided in the cleaning device 6 shown in FIG. The residual potential on the surface of the photoconductor 1 is eliminated by the elimination light 7A from the quenching lamp 7 that is turned on after the cleaning operation. This static elimination operation ends the image forming process for one image.

On the other hand, the toner scraped off by the cleaning blade 6a is, as shown in FIG. 6, a toner collecting portion 8C formed in the case 14A of the process unit 14.
It is supposed to be collected in. The collected toner is
A toner conveying coil 8B, which constitutes a part of the toner recycling unit 8 arranged in the toner collecting section 8C, conveys the toner to the toner conveying section 8A integrally formed in front of the case. The toner carrying coil 8B is driven by a driving unit (not shown).
It is adapted to be rotationally driven when the device 100 is operated.
As shown in FIG. 3, the toner carried to the toner carrying section 8A is recycled in the toner carrying path 8D provided between the toner carrying section 8A and the developer stirring section 11 connected to the developing section 4. The belt 9 allows the developer stirring section 11
It is being transported to and reused.

The recycle belt 9 is wound around a roller 81 fixed to the end of the rotary shaft 80 of the toner carrying coil 8B and a roller 82 rotatably supported by the case 14A near the developer stirring section 11. ing. When the toner carrying coil 8B is rotationally driven, the recycle belt 9 is synchronized with the rotation thereof and rotates clockwise here.

As shown in FIG. 7, the toner conveying path 8D and the developer agitating portion 11 have a case 14A near the roller 82.
Are communicated with each other through the opening 25 formed in the. A filter 26 as a foreign matter removing member is attached to the opening 25. In the filter 26, a mesh portion 26b having a size smaller than the gap L between the developing roller 4a and the doctor blade 10 shown in FIG. 4 is formed in the center of a rectangular and thin plate-like base portion 26a. The filter 26 includes a pair of recesses 25 formed near the opening 25.
It is inserted into a and 25b from above.

The developing roller 4a has a fixed shaft in which a magnet with five poles is arranged, the outer peripheral surface of which is covered with a non-magnetic pipe material. Moves on the developing roller 4a.
This developer is a dry two-component developer composed of small iron balls called a carrier and toner. The developer is
The developer is stirred and circulated in the developer stirring unit 11 shown in FIGS. 2 and 3 by the stirring screws 11A and 11B. The toner has an electric charge by these stirring operations, adheres to the carrier, and is conveyed to the developing roller 4a. Of the developer, the carrier circulates, but the toner adheres to the electrostatic latent image on the photoconductor 1 and is consumed.

In the developer stirring section 11, a density sensor 31 for detecting the toner density is arranged. The density sensor 31 issues a toner replenishment signal when the toner density falls below the reference density.

A toner replenishing device 28 having a toner bottle 27 containing replenishment toner is detachably supported by the process cartridge 14. The toner replenishing device 28 includes the toner replenishing section 12 formed on the case 14A.
In addition, the toner is replenished with new toner, and when the toner replenishment signal is issued, the replenished toner is discharged from the toner bottle 27 to the toner replenishing section 12.

The toner replenishing section 12 includes a toner replenishing device 28.
A replenishment mylar 13b provided on the replenishment shaft 13a in a portion for equalizing the density of the toner replenished from
And a small hole mylar 15 having a toner passage hole formed therein.
Is rotated so as to be conveyed little by little from the toner passage hole of the small hole mylar 15 to the developer stirring section 11.

According to the image forming apparatus 100 having such a configuration, the transfer paper P is transferred from the paper feed cassette 17 to the paper feed roller 19
When the paper is fed by the paper feed roller pair 18, the paper feed path 1
04 is conveyed and is formed so as to be inverted from the paper feed cassette 17 toward the transfer portion A. Therefore, the front and back surfaces of the transfer paper P before the registration roller pair 20 are reversed from those in the paper feed cassette 17. And then transported. When the inverted transfer paper P is sent by the registration roller pair 20 at the timing when the toner image formed on the photoconductor 1 at the transfer portion A and the leading edge of the paper match, the transfer roller 5 is transferred at the transfer portion A.
The transfer operation is performed by the transfer bias from. The transferred transfer paper P passes through the fixing unit 16 to fix the image, and is discharged to the discharge tray 105.

In the present embodiment, since the paper feed cassette 17 is stored inside the apparatus 100 by the so-called front loading method, the paper feed cassette 17 is transferred to the transfer paper P more than the equipment mounted outside the apparatus 100. Less foreign matter such as dust and dirt adheres. Further, since the transfer sheet P is inverted and conveyed in the sheet conveying path 104 before reaching the transfer section A, even when foreign matter is attached to the upper surface in the sheet feeding cassette 17, At the transfer portion A, the back surface in the cassette is the surface facing the photoconductor 1. Therefore, since the image is transferred onto the surface of the transfer paper P on which no foreign matter is attached, a good transferred image can be obtained without being affected by the foreign matter attached to the transfer paper P, and the photosensitive member 1 is also provided. Foreign matter is also prevented from adhering to the surface. Therefore, it is possible to prevent foreign matter from entering the toner that is cleaned and recycled from the photoconductor 1 from the photoconductor 1.

Further, since the filter 26 having the mesh portion 26b smaller than the gap L is provided in the toner recycling path 8D, foreign matter larger than the gap L is blocked by the filter 26. Therefore, among the foreign substances that are mixed little by little into the recycled toner conveyed into the developing and stirring unit 11, foreign substances larger than the gap L are excluded from the recycled toner, and clogging of the foreign substances in the gap L is prevented. Therefore, it is possible to reliably prevent an abnormal image such as white stripes caused by clogging of foreign matter.

In this embodiment, since the charging roller 2 and the transfer roller 5 are used as the bias roller method instead of the corona discharge method as the charging means and the transfer means, the ozone generation is 1/100 as compared with the corona discharge method. To 1/1
It will be extremely low at around 000. Therefore, the fan 110
Since the exhaust capacity of can be weaker than the corona discharge method,
The airflow flowing in the device 100 is weakened, and foreign matters such as dust and dust accumulated in the device 100 over time are less likely to fly. When the air flow in the apparatus 100 can be weakened in this manner, foreign matter such as paper scraps scraped off the driven roller 20b by the blade member 30 and accumulated is less likely to fly, and foreign matter mixed in the recycled toner through the photoconductor 1 is prevented. Will be reduced.

Since the recycled toner carrying path 8D in this embodiment is housed in the case 14A of the process cartridge 14 in which the photoconductor 1, the doctor blade 10, the developing means 4 and the cleaning means 6 are integrated, the toner carrying path 8D. Unlike the case where 8D is provided separately from the cartridge 14, there is no joint between the cartridge and the conveyance path 8D, and there is no toner leakage at the joint. Further, since the toner transport path 8D is integrated, the space in the apparatus 100 becomes smaller than that in the case where the toner transport path 8D is separate from the cartridge 14. The assemblability to the device 100 is improved.

[0033]

According to the present invention, foreign matter such as dust, dust, and paper dust can be prevented from entering the recycled toner very little, so that the abnormal image generated on the transfer paper due to the foreign matter can be effectively reduced. .

According to the first aspect of the present invention, since the paper feeding means is housed inside the apparatus, dust and dust are less likely to adhere to the apparatus for transfer. It is possible to reduce the mixture of foreign matter. As a result, abnormal images are prevented from occurring due to foreign matter within the set number of sheets (life) of the process cartridge, durability of the process cartridge and space efficiency are improved, and abnormal image generation is achieved at low cost and space saving. it can.

According to the second aspect of the invention, in addition to the structure of the first aspect, a fine foreign matter removing member having a mesh smaller than the gap between the developing roller and the toner regulating member is provided in the toner conveying path. Foreign matter larger than the gap contained in the recycled toner is removed from the recycled toner, clogging of the foreign matter in the gap can be reliably prevented, and the occurrence of an abnormal image due to the foreign matter can be further prevented.

According to the invention of claim 3,
In addition to the structure of 2, since the bias roller system is used for at least one of the transfer unit and the charging unit, ozone generation is significantly lower than that of the corona discharge system. As a result, the air flow for ventilation inside the device can be weakened, so that the rising of foreign matter can be suppressed, and the foreign matter that has adhered to the photoconductor and mixed in the recycled toner can be reduced, and the occurrence of abnormal images can be prevented more reliably. can do.

According to the invention of claim 4, in addition to the structure of claim 3, foreign matter adhering to the paper feed roller is removed by the removing member, so foreign matter mixed in recycled toner from the paper feed roller via the photoconductor is reduced. At the same time, foreign matter removed by the removing member can be prevented from being mixed with recycled toner due to re-floating, and the occurrence of abnormal images can be prevented more reliably.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a process cartridge having a toner recycling mechanism.

FIG. 3 is a perspective view showing a schematic internal configuration of a process cartridge.

FIG. 4 is an enlarged view showing a gap between a developing roller and a toner regulating member.

FIG. 5 is a partially cutaway perspective view showing a paper feed roller and a removing member.

FIG. 6 is a perspective view showing a toner transport path in the toner recycling mechanism.

FIG. 7 is a perspective view showing a foreign matter removing member provided in the toner conveying path.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging means 4 Developing means 4a Developing roller 5 Transfer means 8 Toner recycling mechanism 8D Toner conveying path 10 Toner regulating member (doctor blade) 14 Process cartridge 17 Paper feeding means 20 Paper feeding roller (registration roller) 26 Foreign matter removing member ( Filter) 30 Removal member 100 Image forming apparatus 100A Image forming apparatus Front of apparatus L Gap P Transfer paper

Claims (4)

[Claims] 1. An image forming apparatus including a process cartridge having a toner recycling mechanism for transporting toner remaining on a photoconductor to a developing means for reuse, in which front transfer is performed by replenishing transfer paper from the front of the image forming apparatus. An image forming apparatus comprising a paper feeding unit of a system. 2. The developing means is a dry two-component developing system, and a developing roller constituting the developing means and a regulating member for regulating the amount of toner on the developing roller are provided in a toner conveying path of a toner recycling mechanism. 2. The image forming apparatus according to claim 1, further comprising a mesh-shaped foreign matter removing member having a mesh size smaller than the gap. 3. The image forming apparatus according to claim 1, wherein at least one of the charging means for charging the photoconductor and the transfer means for transferring the toner image onto the transfer paper is of a bias roller type. . 4. The image forming apparatus according to claim 3, further comprising: a paper feed roller that conveys the transfer paper; and a removing member that removes foreign matter adhering to the paper feed roller.