JPH08137264A - Image forming device and process cartridge - Google Patents

Abstract

PURPOSE: To prevent transfer-residual toner, etc., from being insufficiently recovered from the dark potential part of the image carrier in a cleanerless process for recovering the transfer-residual toner, etc., existing on the image carrier after transferring to a developing device by a developing bias. CONSTITUTION: This image forming device provided with an electrifier 8 applying a vibrating voltage and abutting on or approaching a body to be electrified, to electrify its surface, a latent image forming device forming an electrostatic latent image on the electrified image carrier 1, the developing device 2 disposed in proximity to or contact with the image carrier and developing the electrostatic latent image, to form a toner image, a means 4 transferring the toner image formed on the image carrier to a transfer material and a means fixing the transferred image on the transfer material is constituted so as to provide a member for removing the transfer-residual toner, etc., between the latent image forming device and the developing device and a recovering means 11 for directly recovering to a developing unit and recovers the transfer-residual toner, etc., on the image carrier by the recovering means.

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 such as an electrophotographic copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or a printer, generally, an image carrier, that is, a photosensitive drum is charged in a uniform and uniform manner, and an electrostatic latent image is formed on the photosensitive drum. A latent image forming step, a developing step of developing the electrostatic latent image with toner, a transfer step of transferring the toner on the photosensitive drum to a transfer material, a fixing step of fixing the toner on the transfer material, and the transfer An image is formed by a cleaning process of cleaning the toner remaining on the photosensitive drum after the process. In the above structure, the toner collected by the cleaning process for cleaning the toner remaining on the photosensitive drum after the transfer process is stored in the container for disposal.

In recent years, a cleanerless process has been proposed for realizing an extremely efficient image forming apparatus which omits the cleaning step, downsizes the image forming apparatus, and omits maintenance such as discarding toner. In the cleanerless process, the toner is adhered to the exposed portion of the photosensitive drum where the surface potential is attenuated by reversal development, and at the same time, the adhered contaminants such as transfer residual toner remaining on the non-exposed portion and thinly adhered are also removed. Collected. That is, after the toner remaining on the photosensitive drum in the transfer process passes through the charging process, the toner is collected by the developing device by electrostatic force due to the difference between the surface potential of the charged photosensitive drum and the developing bias.

FIG. 5 shows a conventional example. In the figure, reference numeral 1 denotes a rotary drum type electrophotographic photosensitive member (photosensitive drum) as an image bearing member, which is charged by a charging member 8. Reference numeral 9 denotes a laser beam which is an exposure means, and by this, image information is formed on the photosensitive drum 1 as an electrostatic latent image. Then, the latent image is toner-developed by the developing sleeve 2 of the developing device. At the same time, this device without a cleaning blade is a photosensitive drum 1.
The adhered contaminants 10 such as transfer residual toner on the developing sleeve 2
To collect. The developed image is transferred from a paper feeding unit (not shown) to the transfer material 5 introduced into the transfer unit between the photosensitive drum 1 and the transfer roller 4 at an appropriate timing. A doctor blade 3 made of urethane rubber or the like, the base end of which is attached to the developing sleeve container, is elastically contacted with the developing sleeve 2, and the layer thickness of the toner on the surface of the developing sleeve is set to a predetermined value. The transfer material 5 that has passed through the transfer portion is separated from the photosensitive drum 1 and is conveyed to an image fixing portion (not shown) to be repeatedly used for image formation.

However, in order to collect the toner due to the difference between the surface potential of the charged photosensitive drum and the developing bias, it is necessary to return the toner, which has been inverted to the positive polarity by the transfer, to the original negative polarity. The advantage of the method of charging the surface to be charged by contacting or approaching the member to be charged is that adhesion of contaminants 10 such as transfer residual toner on the charging member 8 is less than that when only direct current is applied, but the negative electrode during transfer is used. The transfer residual toner such as the transfer residual toner that has been reversed from the positive electrode to the positive electrode remains in the dark portion potential portion while being reversed and is developed, so that the dark portion potential (−
With the potential difference between 700 V) and the potential of the developing sleeve 2 (-500 V), the adhered contaminant 10 such as the positive transfer residual toner cannot be collected by the developing sleeve 2.

[0006]

Problems to be solved by the above-mentioned image forming apparatus of the cleanerless process are as follows. In the method of applying an oscillating voltage to charge or charge the surface of the charged body by bringing it into contact with or close to the charged body, the transfer residue that was reversed from the negative electrode to the positive electrode during transfer remains in the dark potential area while being reversed. Therefore, it cannot be collected by the developing sleeve.

An object of the present invention is to improve the above problems.

[0008]

According to the present invention, the above-mentioned problems are caused by the transfer residual toner and the transfer material existing on the image carrier between the latent image forming device and the developing device rubbing against the drum. The problem is solved by providing a member for removing adhered contaminants such as paper dust and paper fluff generated by the above, and having a means for directly collecting in a developing device instead of a developing sleeve.

[0009]

By using the means as described above, the transfer residual toner existing on the image carrier, the paper dust generated by the transfer material rubbing against the drum, and the adhered contaminants such as paper fluff are removed. By directly collecting them in the developing device instead of the developing sleeve, the usage efficiency of the toner can be greatly improved.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(Embodiment 1) FIG. 1 is a sectional view of an example of an image forming apparatus according to the present invention. This example is an image forming apparatus using an electrophotographic process. The image bearing member 1 is a rotating drum type electrophotographic photosensitive member (photosensitive drum), and is charged by the charging member 8. Oscillation voltage Vpp is 2 for charging
This is a charging method in which a voltage of kV and a DC voltage of -720V are applied, and the surface of the member to be charged is charged by contacting or approaching the member to be charged, and the charging potential (dark portion potential) was set to -700V.
Next, 9 is a laser beam which is an exposing means, whereby image information is formed on the photosensitive drum 1 as an electrostatic latent image, and the light portion potential is set to -150V.

Next, the latent image is developed with toner (developing bias of 500 V) by the developing sleeve 2 of the developing device which is close to or in contact with the photosensitive drum 1, and the developed image is fed from a paper feeding section (not shown) at an appropriate timing. The image is transferred onto the transfer material 5 introduced into the transfer portion between the photosensitive drum 1 and the transfer roller 4. A doctor blade 4 made of urethane rubber or the like having a base end attached to a developing sleeve container is in elastic contact with the developing sleeve 2, and the toner layer thickness on the surface of the developing sleeve 2 is a predetermined value −7 μC / g.

As the developer, magnetic, non-magnetic, polymerized or pulverized can be used. The transfer material 5 that has passed through the transfer portion is separated from the photosensitive drum 1 and is conveyed to an image fixing portion (not shown).
The adhered contaminants 10 such as the transfer residual toner are charged by the charging member 8 in the same manner as the photosensitive drum 1 and exposed. The density of adhered contaminants such as transfer residual toner covering one round of the photosensitive drum 1 is 0.1 mg / cm ² or less, and the average particle size is 10 μm or less. The spot diameter of the laser beam 9 for realizing 600 DPI is 75 to 90 μm. According to experiments, adhered contaminants such as transfer residual toner for one round of the photosensitive drum 1
0 density is 0. If it was 5 mg / cm ² or less, there was no image disturbance due to light shielding. As a result, image information is formed on the photosensitive drum 1 as an electrostatic latent image.

Next, adhered contaminants 10 such as transfer residual toner
Are mechanically removed by the pre-developing blade 11, and the latent image is developed with toner by the developing sleeve 2 of the developing device. The adhered contaminants 10 such as transfer residual toner mechanically removed by the pre-development blade 11 are collected by the developer (toner) hopper 6, stirred by the stirring member 7, and reused. The developed image is transferred from a paper feeding unit (not shown) to the transfer material 5 introduced into the transfer unit between the photosensitive drum 1 and the transfer roller 4 at an appropriate timing. A doctor blade 3 made of urethane rubber or the like, the base end of which is attached to the developing sleeve container, is elastically contacted with the developing sleeve 2, and the layer thickness of the toner on the surface of the developing sleeve is set to a predetermined value. The transfer material 5 that has passed through the transfer portion is separated from the photosensitive drum 1 and is conveyed to an image fixing portion (not shown) to be repeatedly used for image formation.

As described above, the adhered contaminants 10 such as the transfer residual toner are mechanically removed by the pre-developing blade 11, collected in the developer (toner) hopper 6, and stirred by the stirring member 7.
By reusing the toner, it is possible to greatly improve the use efficiency of the toner and obtain stable high-quality development.

(Embodiment 2) FIG. 2 shows a second embodiment of the present invention. The present embodiment is characterized in that a component magnetic toner is used as a developer to magnetically remove adhered contaminants 10 such as transfer residual toner existing on the photosensitive drum 1.

In this embodiment, after the image information is formed on the photosensitive drum 1 as an electrostatic latent image, the adhered contaminants 10 such as transfer residual toner are magnetically removed by the rotating pre-developing magnet roller 12. . The latent image is toner-developed by the developing sleeve 2 of the developing device. Attached contaminants 10 such as transfer residual toner magnetically attracted onto the pre-development magnet roller 12
Is separated from the pre-development magnet roller 12 by the magnet roller cleaner 13 and the developer (toner) hopper 6
It is recovered by the agitator 7, agitated by the agitating member 7, and reused.

The developed image is transferred from a paper feeding unit (not shown) to the transfer material 5 introduced into the transfer unit between the photosensitive drum 1 and the transfer roller 4 at an appropriate timing. A doctor blade 3 made of urethane rubber or the like, the base end of which is attached to the developing sleeve container, is in elastic contact with the developing sleeve 2, and the layer thickness of the toner on the surface of the developing sleeve is set to a uniform predetermined value. The transfer material 5 that has passed through the transfer portion is separated from the photosensitive drum 1 and conveyed to an image fixing portion (not shown),
It is repeatedly used for image formation.

As described above, the adhered contaminants 10 such as the transfer residual toner are magnetically attracted to the pre-development magnet roller 12, and the magnet roller cleaner 1 such as urethane rubber is used.
At 3, the magnet is separated from the pre-development magnet roller 12, collected in the developer (toner) hopper 6, and stirred by the stirring member 7,
By reusing the toner, it is possible to significantly improve the use efficiency of the toner and obtain stable high-quality development. Further, the photosensitive drum 1 and the pre-development magnet roller 12
Since it is installed in a non-contact manner, there is no scraping of the drum and the life of the cartridge can be extended.

(Embodiment 3) FIG. 3 shows a third embodiment of the present invention. In this embodiment, the developer is magnetic, non-magnetic, polymerized or pulverized to electrically remove the adhered contaminants 10 such as the transfer residual toner existing on the photosensitive drum 1.

In this embodiment, after the image information is formed on the photosensitive drum 1 as an electrostatic latent image, the adhered contaminants 10 such as transfer residual toner are collected and removed by the pre-developing roller 14 which rotates by electrostatic force. It The latent image is toner-developed by the developing sleeve 2 of the developing device. Adhered contaminants 10 such as transfer residual toner that have been electrically attracted to the pre-developing roller 14 that is in contact with or close to the photosensitive drum 1 are separated from the developing roller 14 by a roller cleaner 15 such as urethane rubber and the developer (toner) hopper. 6 and is stirred by the stirring member 7,
Be reused.

The developed image is transferred to a transfer material 5 introduced into a transfer portion between the photosensitive drum 1 and the transfer roller 4 from an unillustrated paper feeding portion at an appropriate timing. A doctor blade 3 made of urethane rubber or the like, the base end of which is attached to the developing sleeve container, is elastically contacted with the developing sleeve 2, and the layer thickness of the toner on the surface of the developing sleeve is set to a predetermined value. The transfer material 5 that has passed through the transfer portion is separated from the photosensitive drum 1 and is conveyed to an image fixing portion (not shown) to be repeatedly used for image formation.

The voltage applied to the pre-developing roller 14 must be set within a range of VD value ± 550V so that discharge does not occur with respect to the charging potential (VD value) of the photosensitive drum 1. The magnitude of the VD value is selected so that the toner is attracted depending on the polarity of the toner after charging. In this embodiment, since the photosensitive drum 1 is charged to -700V and subjected to reversal development, a voltage of -200V was applied to the pre-developing roller 14 to collect the negatively charged toner. When collecting the positive charging toner, a voltage of -1200 V may be applied to the pre-developing roller 14. If the material of the pre-developing roller 14 is a conductor, there is no particular problem.

As described above, the adhered contaminants 10 such as the transfer residual toner are electrically attracted onto the pre-developing roller 14, and the pre-developing roller 14 is protected by the roller cleaner 15 such as urethane rubber.
Further separated and collected in the developer (toner) hopper 6,
By stirring with the stirring member 7 and reusing it, it is possible to significantly improve the use efficiency of the toner and obtain stable development. In addition, the photosensitive drum 1 and the pre-developing roller 1
Since No. 4 is installed in a non-contact manner, the drum is not scraped and the life of the cartridge can be extended.

(Embodiment 4) In FIG. 4, image information is formed as an electrostatic latent image on the photosensitive drum 1 in Embodiment 1, and adhered contaminants 10 such as transfer residual toner are mechanically removed by a blade 11 before development. After removal, the latent image is developed with toner by the developing sleeve 2 of the developing device. While the contaminants 10 such as transfer residuals mechanically removed by the pre-development blade 11 are collected by the developer (toner) hopper 6, the toner and the transfer material 5 rub against the photosensitive drum 1. It is characterized in that a mesh sheet 16 for distinguishing adhered contaminants such as paper dust and paper fluff generated by the above is installed. The mesh-like sheet 16 can prevent a foreign material having a large diameter from being mixed into the developer (toner) hopper 6, which enables more stable development with high image quality.

(Embodiment 4) In the present embodiment, the process cartridge has a toner collecting means and physically accommodates at least one of a charging device, a member to be charged (latent image carrier) and a developing device. In addition, the toner collecting unit has the same structure as that described in the first to third embodiments. Since the process cartridge itself is known, the illustration of this embodiment is omitted.

[0027]

As described above, the transfer residual toner existing on the image bearing member, the paper dust generated by the transfer material rubbing against the drum, the adhered contaminants such as paper fluff, and the like are developed. Instead of using the sleeve, the toner can be directly collected in the developing device and reused to greatly improve the toner usage efficiency.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a sectional view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a sectional view of an image forming apparatus according to a third embodiment of the present invention.

FIG. 4 is a sectional view of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Developing sleeve 3 ... Doctor blade 4 ... Transfer roller 5 ... Transfer material 6 ... Toner hopper 7 ... Stirring member 8 ... Charging member 9 ... Laser light 10 ... Transfer residual toner and other contaminants 11 ... Before development Blade 12 ... Magnet roller before development 13 ... Magnet roller cleaner 14 ... Roll before development 15 ... Roller cleaner 16 ... Mesh sheet

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G03G 21/10 (72) Inventor Hiroaki Ogata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. In-house (72) Inventor Hiroki Kizu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Michihito Yamazaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (5)

[Claims] 1. A charging device for applying an oscillating voltage to contact or approach a charged body to charge a surface of the charged body, a latent image forming apparatus for forming an electrostatic latent image on a charged image carrier, A developing device, which is disposed in proximity to or in contact with the image carrier to develop the electrostatic latent image to form a toner image, means for transferring the toner image formed on the image carrier to a transfer material, and In an image forming apparatus having means for fixing a transfer image on a transfer material, a member for removing adhered contaminants such as transfer residual toner existing on the image carrier between the latent image forming apparatus and a developing device is provided. An image forming apparatus provided with a collecting means for collecting directly to a developing device. 2. The image forming apparatus according to claim 1, wherein the collecting unit mechanically removes transfer residual toner existing on the image carrier. 3. The image forming apparatus according to claim 1, wherein the collecting unit magnetically removes the transfer residual toner existing on the image carrier. 4. The image forming apparatus according to claim 1, wherein the collecting unit electrically removes the transfer residual toner existing on the image carrier. 5. The at least one of a charging device, a member to be charged (latent image bearing member), and a developing device, which physically comprises the collecting device according to any one of claims 1 to 4, and A process cartridge that is detachably attached to the main body of the image forming apparatus.