JPH03228081A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate toner which is left without being eliminated and to stably output an excellent image for a long time by disposing a second cleaning means between a first cleaning means which cleans the surface of an image carrier after the image is transferred and a contact electrostatic charge device. CONSTITUTION:A stain preventing roller 8 is disposed between the rubber blade 4a of a first cleaning device 4 and an electrostatic charge roller 2 being as a contact electrostatic charge member by bringing it into contact with the surface of a photosensitive body 1. The roller 8 has a sponge-like texture and consist of EPDM and it is driven and rotated in accordance with the rotation of the photosensitive body 1. Then, since the toner or the like, which is left without being eliminated and which is passed through the abutting part of the blade 4a of the cleaning device 4 and the photosensitive body 1 is collected by the roller 8, the surface of the body 1 is cleaned again. As the result, the toner which is left without being eliminated does not arrive at the electrostatic charge roller 2.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an image forming apparatus.

More specifically, target image information is applied to the image carrier surface by an image forming process means that includes a step of charging an image carrier such as an electrophotographic photoreceptor or an electrostatic recording dielectric material such as a rotating drum type or rotating belt type. The present invention relates to a transfer type image forming apparatus in which a transferable image is formed and supported, the transferable image is transferred to a transfer material, and the image carrier after the image transfer is cleaned by a cleaning means and repeatedly used for image formation.

(Prior Art) Conventionally, it has been used as a device for charging the surface of an image bearing member such as a photoreceptor or dielectric material in a copying machine, a laser beam printer using electrophotography, a recording device using electrostatic recording method, etc. In most cases, a corona discharger whose main components are a wire electrode and a shield electrode is used.

A corona discharger has the advantage of being simple in structure and providing relatively stable charging performance, but has the disadvantage of generating a large amount of ozone and ozone products in the case of negative corona discharge. Furthermore, if the corona wire becomes dirty, there are other problems such as uneven discharge and charging failure.

Therefore, in recent years, consideration has been given to adopting a contact charging method instead of a corona discharger, which has many problems. ! In tactile charging, a voltage (for example, 1 to 2 KV
Electricity is directly applied to the surface of the image carrier by contacting a conductive member (charging member) such as a roller, blade, or plan shape to which a DC voltage of about 200 yen or a superimposed voltage of a DC voltage and an AC voltage ($) is applied. This method charges the surface of the image carrier to a predetermined potential by transferring (injecting) the electrolyte to the image bearing member, and has the advantages that the voltage of the charging device can be lowered and that the amount of ozone generated is extremely small.

FIG. 8 shows a schematic configuration of an example of an image forming apparatus using a contact charging device. l is a drum-shaped electrophotographic photoreceptor as a t carrier, and a predetermined 15
It is driven to rotate at high speed.

Reference numeral 2 denotes a charging roller as a contact charging member that is brought into contact with the surface of the photoreceptor l with a predetermined pressing force, and a predetermined voltage is applied by a power supply device (not shown). The peripheral surface of the rotating photoreceptor 1 is uniformly charged to a predetermined potential by contact charging by the charging roller 2.Then, the surface of the photoreceptor 1 is uniformly charged. When the target image information is written and exposed by laser beam scanning, the potential of the laser-exposed photoreceptor surface is attenuated, and an electrostatic latent image corresponding to the target image information is sequentially formed on one surface of the photoreceptor. To go.

The formed latent image is developed as a toner image (transferable image) in a developing device 3, and the toner image is transferred from a paper feed section (not shown) to a photoreceptor l and a transfer roller 5 (transfer section) in a predetermined synchronization manner. The images are sequentially transferred onto the recording material 6 which is then fed.

The recording material 6, which has undergone the image transfer through the transfer section, is separated from the surface of the photoreceptor and introduced into an unillustrated chamber, where the transferred image is fixed.

First, the surface of the photoreceptor after the image transfer is cleaned by a cleaning device 4 to remove deposits such as residual toner from the surface of the photoreceptor, and is again subjected to the image forming process including the charging process by the charging roller 2. This allows the image to be created repeatedly.

(Problems to be Solved by the Invention) Various types of cleaning means 4 are known for removing and cleaning residual toner, etc. from the surface of the photoreceptor after image transfer. The device shown in FIG. 8 is a blade cleaning device, in which the tip edge of a rubber blade 4a serving as a cleaning blade is brought into contact with the surface of the photoconductor 1 in the counter direction in the plane movement direction to remove the transfer residue from the photoconductor 1 surface. It cleans the surface of the photoreceptor by efficiently scraping off toner, etc. Ideally, the cleaning device M4 should completely remove the transferred residual toner from one surface of the photoreceptor. Even though the plate cleaning device is highly efficient, it is not perfect.
It is difficult to prevent the charge control agent contained in the toner, auxiliary agents such as silica for increasing image filtration, and the like from sometimes passing through the contact portion between the edge portion of the rubber blade 4a and the photoreceptor l.

Then, a charging member (
In the example shown in FIG. 8, in the case of a contact charging device in which a charging roller 2) is pressed into contact with the charging roller 2), toner and the like that have passed through the cleaning device 4 and are not removed adhere to the charging roller 2, which is a charging member. The attached toner, etc. is transferred to the photoreceptor 1 of the charging roller 2.
The pressure contact force causes the photoreceptor to be firmly attached to or embedded in the surface of the photoreceptor, resulting in complete adhesion and removal of the cleaning device! Even if it is subjected to cleaning action again in step 4, it is not removed.
This may result in defects in the output image.

The present invention solves the above-mentioned problems with transfer type image forming apparatuses that use a contact charging device as a charging processing means for a photoreceptor, that is, an image carrier, and stably outputs good images over a long period of time. The purpose is to provide a device that is devised so that it can be used.

(Means for Solving the Problems) The present invention forms and carries a transferable image of desired image information on the surface of an image carrier by an image forming process means including a step of charging the image carrier, and the transferable image The image forming apparatus transfers the image to a transfer material, and after the image transfer, the image bearing member is cleaned by a cleaning means and used for image formation repeatedly. It is a contact charging device that charges the object by contacting it with the body surface, and when the cleaning device for the image bearing member after image transfer is used as a first cleaning device, there is a gap between the first cleaning device and the contact charging device. The image forming apparatus is characterized in that a second cleaning means is provided for re-cleaning the surface of the image carrier that has been cleaned by the first cleaning means.

(Function) That is, between the first cleaning means for cleaning the surface of the image carrier after image transfer and the contact charging device, the second cleaning means for re-cleaning the surface of the image carrier that has been cleaned by the first cleaning means. By disposing the toner, the toner that has not been removed by the first cleaning device is removed from the surface of the image carrier by the second cleaning device before reaching the charging member of the contact charging device.

Therefore, toner or the like that has been removed and leaked by the first cleaning means is carried to the charging member and firmly adheres to the image carrier surface by the pressing contact force of the charging member against the image carrier surface.
Image defects caused by the adhesion are effectively prevented.

(Examples) Example 1 (FIG. 1) FIG. 1 is a schematic diagram of the main parts of an example of an image forming apparatus according to the present invention, in which a second cleaning means is provided.

This example device has a contact charging IIL1 similar to the device shown in FIG.
It is a laser beam printer using a transfer type electrophotographic process using the i, and has the same components and parts as the example device in Figure 8.
The same reference numerals are given to the parts, and repeated explanations are omitted.

The rotating drum-type electrophotographic photoreceptor 1 serving as a carrier is an OPC photoreceptor in this example. Photoreceptor l is selenium-based or C
Other photoreceptors such as dS-based, silicon-based, and zinc oxide-based photoreceptors may also be used.

Reference numeral 2a denotes a power supply section that applies a predetermined bias voltage to the charging roller 2 as a contact charging member.

The laser beam scanning exposure was modulated in response to electrical digital time-series pixel signals of target image information inputted from a not-shown laser beam scanner to a host device such as an electronic computer, wort processor, or image reading device. This is done by outputting a laser beam and main scanning it in the generatrix direction of the photoreceptor I.

The developing device 3 of this embodiment uses a developing sleeve type one-component magnetic toner as a developer, using a developing member formed by inserting a developing magnet 3a inside a developing sleeve 3b. The developing sleeve 3b remains fixed without rotating, and only the developing sleeve 3b rotates in the direction of the arrow, and the one-component magnetic toner, which is the developer in the developing device, is regulated by the rubber blade 3c and coated on the developing sleeve 3b with a uniform thickness. be done. Then, by the developing sleeve 3b to which a superimposed voltage of AC+DC is applied as a developing bias by an AC bias power source (not shown) and a DC bias power source.

Toner adheres to the area where the potential of the photoreceptor is attenuated due to foggy light, and the electrostatic latent image is developed (reverse development).

A transfer roller 5 which is in pressure contact with the photoreceptor l as a transfer means
In this example, the resistivity is 1♂ΩCm over the entire length (full width)
Using the following elastic roller, transfer was performed by applying a transfer bias with a polarity opposite to the potential of the photoreceptor 1 and the polarity of the developer of the toner image using the bias power supply 7.

After the image has been transferred, the surface of the photoconductor 1 is cleaned by collecting and removing the residual toner after transfer with a blade cleaning device 4 (a first cleaning device) 4a made of urethane with a thickness of 2 thick (urethane rubber plate) 4a. Subjected to formation. A blowout prevention sheet 4b of PUT (polyethylene phthalate) having a thickness of 50 μm is attached to the cleaning device 4 to prevent the collected toner from blowing out.

Reference numeral 8 designates a dirt prevention roller as a second cleaning device, which is disposed in contact with the surface of the photoreceptor 1 between the rubber blade 4a of the first gluing device M4 and the charging roller 2 as a contact charging member. .

This roller 8 is made of EPDM and has a spongy texture, and rotates as the photoreceptor 1 rotates. The remaining toner that has passed through the contact portion between the rubber blade 4a of the first cleaning device W4 and the photoreceptor l, that is, a trace amount of toner and the charge control agent contained in the toner, increases the image filtration and removes the toner. Silica, which is added to improve fluidity, and paper dust from the recording material are collected by this stain prevention roller 8, and the surface of the photoreceptor 1 is re-cleaned.
It does not reach the charging roller 2.

Therefore, the leaked toner removed by the first cleaning device W4 adheres to the charging roller 2, and the pressing contact force of the charging roller 2 against the surface of the photoreceptor causes it to firmly adhere to the surface of the photoreceptor. Image defects caused by adhesion are effectively prevented.

Note that this example 1 Jli is a photoconductor 1, a charging a-ra 2, and a current charger 3.
- Five process devices, including a cleaning device 14 and a dirt prevention roller 8, are assembled in a common cartridge housing 100 in a predetermined arrangement relationship to form a process cartridge that can be attached to and removed from the image forming apparatus body at once. However, since this is outside the main point of the present invention, a detailed explanation will be omitted.

Embodiment 2 (FIG. 2) In this embodiment, the rubber blade 4a of the first cleaning device ff14 is brought into contact with the surface moving direction of the photoreceptor 1 in the forward direction, the dirt prevention roller 8 is made conductive, This configuration is such that a voltage is applied to the roller by a bias voltage of 1 plθ.

In this case, a direct current is applied to the roller 8 to collect foreign matter that has passed through the rubber blade 4a. It is preferable to apply a direct current with a polarity opposite to that of the foreign matter that has passed through it.In this case, the surface of the photoreceptor 1 is charged by the roller 8, but the charging roller 2 is applied with alternating current and direct current, and the photoreceptor 1 There is no problem because the surface is uniformly charged to a predetermined potential by this charging roller. Example 3 (Figure 3) This example device uses the bristle brush cleaning device 12 as the first cleaning device and the second cleaning device. A dirt prevention roller 14 having a clogging property is used as a cleaning device. The movement of the roller 14 is controlled by the solenoid 13 in a direction in which it comes into contact with the surface of the photoreceptor 1 and in a direction in which it moves away from the surface without contact. When the device is stopped for a long time, it is kept separated from the photoconductor without contacting it. ! light body 1
When the roller 14 is rotationally driven, it is held in contact with the roller 14 and rotates as a result of the rotation on the photoreceptor, and the toner and the like removed and leaked from the first cleaning device δ12 is collected on the viscous surface of the roller 14. .

Embodiment 4 (FIG. 4) In the apparatus of this example, the first cleaning device is a blade cleaning device, which cleans one surface of the photoconductor with a rubber blade 4a that is in contact with the counter in the direction of surface movement of the one surface of the photoconductor. Transfer residual toner and the like are removed.

One surface of the photoreceptor that has passed through the rubber blade 4a is an LED.
The surface potential of the photoconductor 1 is lowered (discharged) by exposure processing l by the lamp 16, and then it is re-cleaned by the stain prevention brush 17 as a second cleaning device! The brush 17 collects the toner and the like removed by the cleaning device 4a of s1.

The reason why the LED lamp 16 provides light to the photoreceptor l is that the foreign matter passing through the rubber blade 4a
This is to remove the charge and weaken the adhesion force when the photoreceptor 1 is strongly adhered to the surface of the photoreceptor 1 due to electrostatic adhesion caused by frictional charging due to the sliding contact between the photoreceptor 1 and the photoreceptor 1. The stain prevention brush 17 may be made conductive and a voltage may be applied thereto.

Embodiment 5 (FIG. 5) In this embodiment, a second cleaning means is provided between the charging roller 2 and a rubber blade 4a as a first cleaning means that contacts one surface of the photoreceptor in one direction of the counter. Moltbren (trade name) 19 was applied to one side of the photoconductor and the charging roller 2.
It is placed so that it is in contact with both surfaces.

By doing this, foreign matter passing through the rubber blade 4a,
The liquid seeping out from the charging roller 2 is collected by a malt blend 19 serving as a second cleaning means. This configuration is effective when the charging roller 2 uses a solvent during manufacturing and the solvent remains without being sufficiently dried.

Embodiment 6 (FIG. 6) This embodiment is a contact charging device in which a conductive blade 23 is used as a charging member and is brought into contact with the surface of a photoreceptor with a predetermined pressing force, and the conductive blade 23 is supplied with a predetermined pressure from a bias power source 22. A voltage is applied to contact charge the surface of the photoreceptor to a predetermined uniform potential.

As the cleaning means 81, a rubber blade 4a is used which is in contact with one surface of the photoreceptor in one counter direction. As a second cleaning means, air is blown onto the surface of the photoreceptor 1 through the nozzle 21 using a fan device (not shown), and the air is sucked into the surface of the photoreceptor 1 after passing through the rubber blade 4a.
The surface of the photoreceptor is re-cleaned by removing foreign matter from the surface.

Embodiment 7 (FIG. 7) In this example device, a felt pad 25 as a second cleaning means is pressed against one surface of the photoreceptor between a rubber blade 4a as a cleaning means for St and a charging roller 2. Foreign matter on the surface of the photoreceptor 1 that has passed through the rubber blade 4a is wiped off and removed by the felt pad 25, and the surface of the photoreceptor 1 is re-cleaned.

In this case, the felt pad 25 may be impregnated with a surfactant so that foreign matter passing through the rubber blade 4a can be easily removed from the surface of the photoreceptor.
A release agent such as silicone may be applied to 5 to make it easier for foreign substances to separate from the photoreceptor surface.

(Effects of the Invention) As described above, regarding the transfer method image formation 11tM using a contact charging device as the charging means for the image bearing member, the cleaning means removes residual toner, etc. from the surface of the image bearing member after image transfer. Even if leaked toner or the like occurs, it is prevented from being carried to the contact charging member, so damage to the image carrier due to the removed leaked toner or the like sticking to the surface of the image carrier is eliminated, and the life of the image carrier is extended. It is capable of stably outputting good images over a long period of time, and the intended purpose is well achieved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the first embodiment of the apparatus, and FIGS.
8 are schematic configuration diagrams of main parts of the apparatuses of the second to WIJ7 embodiments, respectively, and FIG. 8 is a schematic configuration diagram of an example of a conventional image forming apparatus. l is a rotating drum-type electrophotographic photoreceptor as an image carrier;
?・23 is a charging roller or a charging blade as a contact charging member, 2ae22 is its bias application power source, and 4 parts 4a
s 12 is a blade cleaning device/rubber blade-bristle brush device as a cleaning device of WIJl, 8
-14-17-19, 21, and 25 are sponge rollers, Φ adhesive rollers, bristle brushes, malt blends, and felt pads in the nozzle, respectively, as second cleaning means.

Claims (1)

[Claims] (1) A transferable image of desired image information is formed and supported on the surface of the image carrier by an image forming process means including a step of charging the image carrier, the transferable image is transferred to a transfer material, and the transferable image is transferred to a transfer material. The image bearing member is an image forming apparatus that is repeatedly cleaned by a cleaning means and subjected to image formation, and the charging processing means of the image bearing member is a contact charging method in which a charging member to which a voltage is applied is brought into contact with the surface of the image bearing member to charge the image bearing member. When the cleaning means for the image bearing member after image transfer is a first cleaning means, an image cleaned by the first cleaning means is provided between the first cleaning means and the contact charging device. An image forming apparatus characterized in that a second cleaning means for cleaning the surface of the carrier again is provided.