JP2001125450A - Image forming device using recycle system for collected toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which can form an excellent image stably for a long period by effectively preventing reverse electrostatically charged toner, paper powder, etc., from entering a developing device and effectively solving problems of toner scattering, a decrease in image density, fogging, toner dust of an image part, etc., as an image forming device which forms an image by a recycle system. SOLUTION: A collected toner sifting device 50 is composed of an insulating roller and a scraping blade 52 which is made to abut against the roller and formed of an insulating material differing in frictional electrostatic charging series from the insulating material forming the roller, and the insulating roller is electrostatically charged to the positive or negative polarity by frictional electrostatic charging with the scraping blade; and toner collected by a cleaning device is supplied onto the insulating roller and thus sifted into toner collected by the insulating roller and toner which is not collected, so that the toner having the same polarity with the electrostatically charged toner is recycled into the developing device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
Related to an image forming apparatus such as a facsimile,
In particular, the present invention relates to an image forming apparatus employing a recycling system.

[0002]

2. Description of the Related Art In an image forming apparatus represented by a copying machine, the surface of a photosensitive drum is uniformly charged, and an electrostatic latent image corresponding to a document image is formed on the surface of the photosensitive drum by image exposure. The electrostatic latent image is developed to form a toner image on the surface of the photoconductor drum, and the toner image is transferred from the surface of the photoconductor drum onto a transfer material such as paper, and the transferred toner image is subjected to heat, pressure, or the like. By fixing, an image is formed.

In such an image forming apparatus, as a developer, a one-component magnetic developer composed of a magnetic toner,
A two-component magnetic developer composed of a toner and a magnetic carrier is widely used, and a developing device for performing development using such a magnetic developer usually includes a developing housing filled with a magnetic developer. The developer housing is accommodated in the developing housing so as to face the surface of the photosensitive drum. That is, the developer transfer sleeve has a structure in which a magnet having a plurality of magnetic poles is provided in a non-magnetic sleeve such as aluminum and the like. The developing agent (charged toner) is transported to the area between the drum and the surface of the drum to perform development.

Recently, from the viewpoint of resource saving and environmental friendliness, after a toner image is transferred onto a predetermined transfer material, the toner image is removed from the surface of the photoreceptor by a cleaning device such as a cleaning blade and collected. 2. Description of the Related Art An image forming apparatus employing a system for recycling and reusing toner in the above-described developing device has been widely used.

[0005]

However, the charged toner having a predetermined polarity used as a developer contains a small amount, but a small percentage, of a reversely charged toner. A large amount of the oppositely charged toner is contained in the collected toner. Therefore,
In an image forming apparatus employing the above-described recycling system, as the toner repeatedly circulates during the image forming process, the amount of the oppositely charged toner increases in the developing device, and the toner contains such an oppositely charged toner. The development with the developer causes inconveniences such as toner scattering, reduction in image density, fog and toner scattering in the image area.
Further, as the image forming process is repeated, paper dust generated from the transfer material (paper) is collected by the cleaning device, and the proportion of paper dust in the developer increases. Or the generation of the oppositely charged toner may be promoted.

Accordingly, it is an object of the present invention to provide an image forming apparatus for forming an image by a recycling system, in which the above-described mixing of the oppositely charged toner and paper powder into the developing device is effectively prevented, and the toner is scattered and the image density is reduced. It is an object of the present invention to provide an image forming apparatus capable of effectively solving problems such as image fogging and toner dust in an image area and stably forming a good image over a long period of time.

[0007]

According to the present invention, a toner image is formed by developing an electrostatic image formed on the surface of a photosensitive drum with a charged toner filled in a developing device. Is transferred onto a predetermined transfer material, the toner remaining on the surface of the photosensitive drum after the transfer of the toner image is collected by a cleaning device, and the collected toner is recycled into the developing device. The roller and an insulating material that is in contact with the roller and constitutes the roller include a scraping blade made of an insulating material having a different frictional charging series. A recovery toner sieving device in which the insulating roller is charged to a positive polarity or a negative polarity is provided, and the toner recovered by the cleaning device is supplied onto the insulating roller. Accordingly, sieved to the toner not collected toner that is collected by the insulative roller,
An image forming apparatus is provided, wherein one of the toners having the same polarity as the charged toner is recycled into the developing device.

In the present invention, the toner collected from the surface of the photosensitive drum by a cleaning device including a cleaning blade or the like is introduced into a collected toner sieving device, and the toner is charged to a normal polarity and reversely charged. It is a remarkable feature that only the toner charged to the regular polarity is recycled into the developing device. The recovered toner sieving apparatus includes an insulating roller and a scraping blade in contact with the insulating roller, and the roller and the blade are formed of insulating materials having different triboelectric series. The insulating roller is charged to a positive or negative polarity by frictional charging with the blade.

For example, when an insulating material for forming the insulating roller and the scraping blade is selected so that the insulating roller is negatively charged by friction, and the recovered toner is supplied onto the insulating roller, the recovered toner is supplied. Among them, those charged to the positive polarity are collected on the insulating roller, and those charged to the negative polarity are not collected by the insulating roller and fall as they are. In this way, the recovered toner is sieved into a positively charged toner and a negatively charged toner. Therefore, when the positively charged toner is used as the developer, the positively charged toner collected by the insulating roller is collected by the scraping blade from the sieved collected toner, and is collected in the developing device. That is, the negatively charged toner (reversely charged toner) not collected by the insulating roller may be discarded. When the negatively charged toner is used as a developer, the positively charged toner (reversely charged toner) collected by the insulating roller is discarded, and the negatively charged toner not collected by the insulating roller is discarded. What is necessary is just to recycle the toner in the developing device.

Further, when an insulating material forming the insulating roller and the scraping blade is selected so that the insulating roller is triboelectrically charged to a positive polarity, the cleaning device removes the insulating material. Of the used toner,
Since the negatively charged toner is collected on the insulating roller, depending on the charging polarity of the toner used as the developer, the toner collected on the insulating roller or the toner not collected is used. May be recycled into the developing device.

Incidentally, polyvinyl fluoride, polyvinylidene fluoride, vinyl fluoride / vinylidene fluoride copolymer, ethylene tetrafluoride / perfluoroalkoxyethylene copolymer resin, ethylene tetrafluoride resin, ethylene tetrafluoride / hexafluoride It is known that a triboelectric series of a fluorine-containing polymer represented by a fluorinated propylene copolymer resin or the like is located closest to the negative polarity. Therefore, by utilizing this, an insulating material constituting the above-described insulating roller and the scraping blade may be selected. For example, an insulating roller is formed using a fluoropolymer as described above, and a polymer other than the fluoropolymer, such as polyolefin, polyamide, polyester, polyurethane, or a polymer such as polycarbonate, forms a scraping blade to insulate the roller. The negative roller is frictionally charged to a negative polarity. Of course, the insulating material that determines the triboelectric charging characteristics of the insulating roller and the scraping blade only needs to form at least the surface of the roller or the blade.

In the present invention, by using the above-mentioned collected toner sieving device, the oppositely charged toner is removed from the toner collected from the cleaning device, and has a regular polarity (the same polarity as the charged toner of the developer). Only the charged toner is recycled into the developing device. Therefore,
Even if the collected toner in the developing device is repeatedly recycled due to the repetition of image formation, the amount of the oppositely charged toner does not increase, and there are inconveniences such as toner scattering, fogging, and toner scattering in the image area due to the oppositely charged toner. Can be effectively prevented.

It is known that paper powder is generally negatively charged. Therefore, when a positively charged toner is used as the toner in the developer, the paper powder exhibits the same behavior as the oppositely charged toner, and causes the above-described inconvenience. However, in the image forming apparatus of the present invention using the recovered toner sieving apparatus, such paper dust is removed in the same manner as the reversely charged toner (negatively charged toner), and only the regular positively charged toner is developed. Since it can be recycled in the apparatus, such inconvenience due to such paper dust can be effectively prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to specific examples shown in the accompanying drawings. FIG. 1 shows an outline of the overall arrangement of the image forming apparatus of the present invention employing a recycling system, and FIG. 2 is a diagram showing the structure of a collected toner sieving apparatus used in the image forming apparatus of FIG.

In FIG. 1, in this image forming apparatus, a main charging device 2, an exposing mechanism 3, a developing device 4, a transfer device are provided around a photosensitive drum 1 rotatably provided in the direction of the arrow in FIG. 5, the static elimination device 6, the cleaning device 7
The photosensitive drum 1 is arranged in this order along the rotation direction of the photosensitive drum 1, and paper or O 2 is placed between the photosensitive drum 1 and the transfer device 5.
A transfer material 10 such as an HP film is passed through, and a fixing device 11 is provided on a discharge path of the transfer material 10.

As the photosensitive drum 1, an inorganic photosensitive drum in which a photosensitive layer such as selenium or amorphous silicon is provided on a conductive base roller of aluminum or the like, or a charge generating agent or a charge transporting agent in a binder resin. An organic photosensitive drum provided with an organic photosensitive layer in which is dispersed is used. As the main charging device 2, there is a roller-type contact charging device, but generally, a corona charger is used, and the main charging device 2 causes the surface (photosensitive layer) of the photosensitive drum 1 to change the type of the photosensitive layer. , And is uniformly charged to a predetermined polarity. At this time, the main charging potential of the photoreceptor surface is usually 200 to 1000 V (absolute value). Next, the image exposure mechanism 3 irradiates the surface of the photoreceptor drum with dot light such as a laser beam corresponding to the original by reflected light of the original or an electric signal from a computer or the like. A latent image is formed, the electrostatic latent image is developed by the developing device 4, and a toner image 15 is formed on the surface of the photosensitive drum 1. The transfer device 5 generally includes a transfer charger 5a and a separating charger 5b, and the back surface of the transfer material 10 introduced between the transfer device 5 and the photosensitive drum 1 is transferred to the toner by the transfer charger 5a. The toner image 15 is transferred onto the transfer material 10 by an electrostatic attraction between the charge and the toner image 15 to form a transfer toner image 16. At the same time as the toner image 16 is formed, the transfer material 1 is charged with an alternating current by the separation charger 5b.
0 is quickly separated from the surface of the photosensitive drum 1. Note that a transfer roller can be used as the transfer device 5, and in this case, a transfer material separating device such as the separating charger 5a is not required.

The transfer material 10 having the transfer toner image 16 is
The transfer toner image 16 is conveyed to the fixing device 11 and is fixed on the surface of the transfer material 10 by heat, pressure or the like. On the other hand, after the toner image 15 is transferred onto the transfer material 10, the surface charge of the photosensitive drum 1 is removed by light irradiation by the charge removing device 6. Further, the toner remaining on the surface of the photosensitive drum 1 is scraped and collected by the cleaning device 7 having a cleaning blade or the like, and the next image forming process is performed. The toner collected in the cleaning device 7 is
Using a transport device such as a spiral, the toner is recycled to the developing device 4 according to the route indicated by 20, and is reused.

In the above-described image forming apparatus, the developing device 4 is composed of a developing housing 30 filled with a magnetic developer, and a developer conveying sleeve (developing sleeve) 31 faces the photosensitive drum 1. (The distance between the sleeve 31 and the drum 1 is generally 0.3 to 1.0.
mm). The developing sleeve 31 has a magnet having a plurality of magnetic poles fixed inside, and conveys the developer in the form of a magnetic brush by rotating the sleeve. That is, as shown in FIG. 1, the developing sleeve 31 rotates the photosensitive drum 1 in the opposite direction (moves in the same direction as the drum 1 in the region facing the drum 1, that is, moves downward from above). The magnetic brush 33 adjusted to have a fixed spike length by the spike blade 32 is applied to the photosensitive drum 1.
Is transported to the area (developing area) facing the.

As the developer, any of a two-component developer composed of a magnetic carrier and an insulating toner and a one-component developer composed of a magnetic toner can be used. Further, a plurality of spirals or paddles 35 are provided in the developing housing 30 at an interval from the developing sleeve 31 so as to circulate and agitate the developer along the axial direction of the developing sleeve 31. It has become. By such circulating feeding and stirring, the toner uniformly mixed and frictionally charged to a predetermined polarity is transported in the form of the magnetic brush 33,
With this toner, the electrostatic latent image formed on the surface of the photosensitive drum 1 is developed, and a toner image 15 is formed on the surface of the photosensitive drum 1. Toner, ie, toner image 1
The charge polarity of 5 is opposite to the charge polarity of the surface of the photosensitive drum 1 when the image formation is performed by so-called regular development, and is opposite to the charge polarity of the surface of the photosensitive drum 1 when the image formation is performed by reverse development. Has the same polarity as the charging polarity of In developing, a bias voltage is generally applied between the photosensitive drum 1 and the developing sleeve 31 (normally, about 100 to 300 V in absolute value in normal development, and about 300 to 700 V in absolute value in reversal development). ).

In the image forming apparatus of the present invention, a collected toner sieving device 50 is provided in the middle of the collected toner circulation path 20 described above. This recovered toner sieving device 5
In FIG. 2 showing the structure of No. 0, a case where a positively charged toner is used as a developer will be described as an example.

In FIG. 2, the recovered toner sieving apparatus 50 is, roughly speaking, an insulating sieving roller 51 rotating in a direction indicated by an arrow A in FIG. And an insulating scraping blade 52. At least the surface of the sieving roller 51 is formed of a fluoropolymer such as tetrafluoroethylene resin, and at least the surface of the scraping blade 52 is formed of an insulating polymer other than the fluoropolymer. By the friction contact, the sieving roller 51
Are negatively charged.

On the other hand, below the sieving roller 51, a first toner collection chamber 56 and a second toner collection chamber 57 partitioned by a partition wall 55 side-by-side are arranged. Has a structure arranged on the partition wall 55. As is clear from FIG. 2, the first toner collecting chamber 56 is located on the upstream side and the second toner collecting chamber 57 is located on the downstream side with respect to the rotation direction of the sieving roller 51. On the toner collection chamber 57,
A scraping blade 52 contacts the sieving roller 51. Further, a transport spiral 60 is provided in the second toner collection chamber 57.

In the recovered toner sieving device 50 having the above-described structure, the toner 65 recovered by the cleaning device 7 is supplied to the portion directly above the sieving roller 51 by the transport spiral 62. Positively charged toner (regularly charged toner) by the sieving roller 51
And negatively charged toner (oppositely charged toner).

That is, since the sieving roller 51 is negatively triboelectrically charged, the positively charged toner 65 a of the toner 65 supplied from directly above the sieving roller 51 is trapped on the surface of the sieving roller 51. The toner is collected, transported to the second toner collecting chamber 57, scraped off by the scraping blade 52, and collected in the second toner collecting chamber 57. The collected positively charged toner 65a is recycled into the developing device 4 by the transport spiral 60 through the path 20 shown in FIG. 1, and is again subjected to development. On the other hand, of the toner 65, the negatively charged toner (reversely charged toner) 65b is not collected by the sieving roller 51, which is frictionally charged to the negative polarity, and falls as it is into the first toner collection chamber 56. Collected and discarded. In this case, since the paper powder generated from the transfer paper 10 is negatively charged,
5b, the toner is collected in the first toner collection chamber 56 and discarded.

As described above, when the positively charged toner is used as the developer, the oppositely charged toner (negatively charged toner) and the paper dust are removed from the toner collected from the cleaning device 7 and are charged normally. Only the collected toner (positively charged toner) is recycled into the developing device 4, and the amount of the oppositely charged toner increases in the developing device even when the collected toner in the developing device is repeatedly recycled by repeating image formation. Never do.

The collected toner sieving apparatus 50 shown in FIG.
In, it is of course possible to form at least the surface of the scraping blade 52 with a fluoropolymer and at least the surface of the sieving roller 51 with an insulating polymer other than the fluoropolymer. In this case, since the sieving roller 51 is positively charged due to the frictional contact between the two, the toner 65b collected in the first toner collection chamber 56 becomes the positively charged toner, and the second toner collection Room 57
The toner 65a collected therein becomes negatively charged toner (oppositely charged toner). Therefore, the transport spiral 60 is provided in the first toner collection chamber 56, and the toner 65b is recycled into the developing device 4.

The case where the positively charged toner is used as the developer has been described above as an example. However, when the negatively charged toner is used as the developer, the sieving roller 5 is used.
The toner collected in the first toner collection chamber 56 and the toner collected in the second toner collection chamber 57 are charged in the developing device 4 in accordance with the triboelectric charge polarity of the toner. And the other oppositely charged toner may be discarded. In FIG. 2, the toner 65 collected by the cleaning device 7 is supplied directly above the sieving roller 51 by the transport spiral 62. However, depending on the space around the cleaning device 7, such a transport spiral may be used. It is also possible to directly supply the toner 65 collected by the cleaning device 7 directly above the sieving roller 51 without using the cleaning roller 62.

[0028]

According to the present invention, the recovery toner sieving device having a predetermined structure is provided in the circulation path of the recycled toner, thereby effectively preventing the reversely charged toner and paper dust from being mixed into the developing device. Toner scattered by the oppositely charged toner,
Fogging, toner scattering of an image portion, and the like are effectively prevented, and a good image can be stably formed over a long period of time.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an overall arrangement of an image forming apparatus of the present invention employing a recycling system.

FIG. 2 is a diagram showing a structure of a collected toner sieving apparatus which is a main part of the present invention used in the image forming apparatus of FIG.

[Explanation of symbols]

1: Photoreceptor drum 4: Developing device 10: Transfer material 15, 16: Toner image 20: Recirculating toner circulation path 50: Recovered toner sieving device 51: Toner sieving roller 52: Scraping blade 55: Partition wall 56: First Toner Collection Room 57: First Toner Collection Room

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Tsutsumi 1-2-28 Tamatsukuri, Chuo-ku, Osaka City Inside Mita Kogyo Co., Ltd. (72) Eiji Tanmura 1-2-28 Takumazo, Chuo-ku, Osaka City Inside Mita Kogyo Co., Ltd. (72) Inventor Shinji Kikuta 1-2-28 Tamazo, Chuo-ku, Osaka-shi Inside Mita Kogyo Co., Ltd. F-term (in reference) 2H034 AA00 AA03 BF03 CB01 CB02 2H077 AA37 AC02 AC13 AC16 AD32

Claims (8)

[Claims] An electrostatic image formed on the surface of a photosensitive drum is developed with a charged toner filled in a developing device to form a toner image, and the toner image is transferred onto a predetermined transfer material. A cleaning device that collects toner remaining on the surface of the photosensitive drum after the transfer of the toner image, and recycles the collected toner into the developing device. The insulating material constituting the roller comprises a scraping blade made of an insulating material having a different triboelectric series, and the triboelectric charging with the scraping blade causes the insulating roller to become positive or negative. A charged toner sieving device is provided. By supplying the toner collected by the cleaning device onto the insulating roller, the toner is separated by the insulating roller. Sieved in a toner not collected and condensed toner, the charged toner and the polarity image forming apparatus characterized by recycling into the developing device any one of the toner are the same. 2. The image forming apparatus according to claim 1, wherein the insulating roller is made of a fluorine-containing polymer and is triboelectrically charged to a negative polarity, and the positively collected toner is collected by the insulating roller. apparatus. 3. A positively charged toner is used as the charged toner, and positively collected toner collected by the insulating roller is recycled into the developing device.
An image forming apparatus according to claim 1. 4. The image forming apparatus according to claim 2, wherein a negatively charged toner is used as the charged toner, and negatively collected toner not collected by the insulating roller is recycled into the developing device. 5. The scraping blade is made of a fluoropolymer, and the insulating roller is triboelectrically charged to a positive polarity, and the insulating roller collects the negatively-charged collected toner. An image forming apparatus according to claim 1. 6. The image forming apparatus according to claim 5, wherein a positively charged toner is used as the charged toner, and positively collected toner not collected by the insulating roller is recycled into the developing device. 7. A negatively charged toner is used as the charged toner, and positively collected toner collected by the insulating roller is recycled into the developing device.
An image forming apparatus according to claim 1. 8. The collected toner sieving device includes two collected toner collection chambers partitioned by a partition wall side-by-side, wherein the insulating roller is disposed on the partition wall, and is provided by the insulating roller. The collected toner that is not collected falls into one collected toner collecting chamber, and the collected toner collected by the insulating roller is scraped by the scraping blade and falls into the other collected toner collecting chamber. The image forming apparatus according to claim 1.