JPH0635301A - Image forming device - Google Patents

Abstract

PURPOSE:To electrify an image carrier while passing residual toner through, to facilitate the maintenance of the residual toner, and to reduce the running cost. CONSTITUTION:An electrifier 102 generates an electric field to the electrostatic latent image carrier 101 to electrify the carrier 101 while allowing the residual toner 106 on the carrier 101 to pass. Then, a development device 104 forms on the surface of the electrostatic latent image carrier 101 a toner image corresponding to an electrostatic latent image on the carrier 101. At the same time, the development device 104 receivers the toner 106 remained on the electrostatic latent image carrier 101 and passed the electrified 102. Subsequently a transfer device 111 transfers the toner image formed on the surface of the carrier 101 to the final recording medium, and a fixing device 114 fixes the toner image transferred to the final recording medium. The electrifier 102 generates the electric field to the electrostatic latent image carrier 101 at the time of recording, but at the time of non-recording it generates an inversed electric field.

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 in an electrophotographic recording apparatus such as a printer or a copying machine.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic recording apparatus, image formation is carried out by each process of charging, exposure, development, transfer, fixing and cleaning. A corona charger is generally used as a charging device for the electrostatic latent image carrier. However, since it is necessary to apply a high voltage of 5 to 10 [kV] to the corona charger, not only is it dangerous, but a power supply for applying the high voltage is also required, which increases the cost. . Further, the corona charger is poor in environmental stability, and when affected by humidity, the charging potential of the electrostatic latent image carrier changes.
Further, since the corona charger utilizes the corona discharge phenomenon, ozone is generated and not only the characteristics of the electrostatic latent image carrier are significantly deteriorated, but also the human body is adversely affected. Therefore, in order to prevent the human body from being adversely affected, an ozone absorption / decomposition filter is provided in the electrophotographic recording device to prevent ozone from flowing out of the electrophotographic recording device. However, the ozone absorbing / decomposing filter has a short service life in which it can absorb and decompose ozone, and must be replaced regularly.

Further, in the electrophotographic recording apparatus, since each process of charging, exposure, development, transfer, fixing and cleaning is required, not only the structure becomes complicated but also the size becomes large. Therefore, there is provided a contact-type charging device in which a conductor is brought into contact with the electrostatic latent image carrier and a DC voltage is applied to the conductor to charge the electrostatic latent image carrier (Japanese Patent Laid-Open No. 56-56). 165166). In addition, a conductive plate member made of an elastic metal (for example, phosphor bronze) or conductive rubber (for example, urethane rubber) is brought into contact with the electrostatic latent image carrier, and a DC voltage and an AC voltage are superimposed. There is provided a contact type charging device which charges the electrostatic latent image carrier by applying it to the conductive plate-like member (Japanese Patent Laid-Open No. Sho 60).
(See Japanese Patent Publication No. 147756).

Since these charging devices do not use a corona charger, they are inexpensive, have good environmental stability, and do not generate ozone. Moreover, since the charging blade and the cleaning blade are made of the same member, and the charging process and the cleaning process are used in common, the number of processes can be reduced, and the electrophotographic recording apparatus can be simplified and downsized.

[0005]

However, in the above-mentioned conventional electrophotographic recording apparatus, the size can be reduced by combining the charging process and the cleaning process, but in general, the transfer process by an electrostatic action is performed. Therefore, when the toner image on the electrostatic latent image carrier is transferred to the final recording medium, the transfer rate is 70 to 90.
It becomes as low as [%].

Therefore, the amount of toner developed in the developing process is 10 to 30 on the electrostatic latent image carrier after transfer.
[%] Remains, and the remaining toner must be collected in the cleaning process. In this case, in order to reduce the size of the electrophotographic recording apparatus, it is necessary to reduce the capacity of the toner storage tank of the cleaner provided for the cleaning process. However, since the amount of residual toner is large compared to the capacity of the toner storage tank, maintenance work for discarding the toner collected in the toner collection tank is required, and the body and clothing are discarded when the toner is discarded. Or the toner is scattered inside and outside the electrophotographic recording apparatus. Further, since the collected toner is discarded, it becomes impossible to use 100% of the toner, and the running cost becomes high.

The present invention solves the above-mentioned problems of the conventional electrophotographic recording apparatus, simplifies the maintenance work of the remaining toner, can reduce the size without a cleaner, and can reduce the running cost. An object of the present invention is to provide an image forming apparatus that is low and can stably record a good image for a long period of time.

[0008]

To this end, in the image forming apparatus of the present invention, an electrostatic latent image bearing member carrying an electrostatic latent image is provided, and the electrostatic latent image bearing member is contacted and charged. A device is provided. The charging device charges the electrostatic latent image bearing member while generating an electric field between the charging device and the electrostatic latent image bearing member and passing the toner remaining on the electrostatic latent image bearing member.

An exposure device is provided to expose the charged surface of the electrostatic latent image carrier to form an electrostatic latent image. Then, the developing device forms a toner image corresponding to the electrostatic latent image on the electrostatic latent image carrier on the surface of the electrostatic latent image carrier. At this time, at the same time, the developing device collects the toner remaining on the electrostatic latent image carrier and having passed through the charging device.

Further, a transfer device transfers the toner image formed on the surface of the electrostatic latent image carrier to the final recording medium,
The fixing device fixes the toner image transferred onto the final recording medium onto the final recording medium. The charging device generates an electric field with the electrostatic latent image carrier during recording, but generates an electric field having a polarity opposite to the polarity during non-recording.

[0011]

According to the present invention, the electrostatic latent image carrier for carrying the electrostatic latent image is provided as described above, and the charging device is provided in contact with the electrostatic latent image carrier. The charging device charges the electrostatic latent image bearing member while generating an electric field between the charging device and the electrostatic latent image bearing member and passing the toner remaining on the electrostatic latent image bearing member.

An exposing device is provided to expose the charged surface of the electrostatic latent image carrier to form an electrostatic latent image. Then, the developing device forms a toner image corresponding to the electrostatic latent image on the electrostatic latent image carrier on the surface of the electrostatic latent image carrier. Further, the transfer device transfers the toner image formed on the surface of the electrostatic latent image carrier onto the final recording medium, and the fixing device fixes the toner image transferred onto the final recording medium onto the final recording medium. After the transfer device transfers the toner image to the final recording medium, the toner remains on the electrostatic latent image carrier, but the toner remains on the electrostatic latent image carrier and passes through the charging device. To the developing device. Then, the developing device forms a toner image and, at the same time, collects the toner remaining on the electrostatic latent image carrier.

The charging device generates an electric field between itself and the electrostatic latent image carrier at the time of recording, but at the time of non-recording, it generates an electric field of the opposite polarity. Therefore, the toner attached to the charging member of the charging device is collected by the electrostatic latent image carrier.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an electrophotographic recording apparatus showing a first embodiment of the present invention. In the figure, a drum-shaped electrostatic latent image carrier 101 is rotated at a constant peripheral speed in the direction of arrow a by a driving unit (not shown). The electrostatic latent image carrier 101 is a conductive support 101.
A photoconductive layer 101b is provided on a, and in this embodiment, an organic photoconductor having a diameter of 30 [mm] is used, but any of a selenium photoconductor, a zinc oxide photoconductor, an amorphous silicon photoconductor, etc. Can also be used.

Next, the image forming process in this embodiment will be described. First, in the charging process, the electrostatic latent image carrier 101 is uniformly and uniformly charged by the charging device 102 provided in contact with the surface thereof. The charging device 102 allows the toner 106 remaining on the electrostatic latent image carrier 101 after transfer to pass between the charging device 102 and the electrostatic latent image carrier 101, or the electrostatic latent image carrier after transfer. It is set so that the toner 106 remaining on 101 is not removed (cleaned). In fact, toner 10
6 remains slightly upstream of the contact portion between the electrostatic latent image carrier 101 and the charging blade 118, but does not increase thereafter and passes between the charging blade 118 and the electrostatic latent image carrier 101. I could observe that. The charging device 1
02 will be described in detail later.

In the exposure process, light corresponding to the image signal is exposed on the electrostatic latent image carrier 101 by the exposure device 103 to form an electrostatic latent image. As the exposure device 103, not only a combination of an LED array and a SELFOC lens (trade name), but also a combination of a laser and an image forming optical system can be used.

In the developing process, the developing device 104, which is in close contact with the electrostatic latent image carrier 101 or is provided at a minute distance, adheres the toner 106 on the toner carrier 105 to form an arrow. And the electrostatic latent image formed on the electrostatic latent image carrier 101 is developed. In this embodiment, the electrostatic latent image carrier 101 is exposed by the exposure device 103.
Reversal development in which the toner 106 is developed on the portion irradiated with light is adopted, and the conductive support 1 of the electrostatic latent image carrier 101 is adopted.
A developing bias voltage is applied between 01a and the toner carrier 105.

By doing so, the toner carrier 10
In the space between the electrostatic latent image carrier 5 and the electrostatic latent image carrier 101, an electric field is generated by the electrostatic latent image formed on the electrostatic latent image carrier 101. Therefore, the charged toner 106 on the toner carrier 105 adheres to the electrostatic latent image carrier 101 by electrostatic force and is developed to form a toner image. As the developing device 104, any of a two-component magnetic brush developing device, a one-component magnetic brush developing device, a one-component non-magnetic developing device and the like can be used. The developing device 104 will be described in detail later.

On the other hand, the recording paper 108, which is the final recording medium accommodated in the paper cassette 107, is taken out by the paper feed roller 109 and the rotation of the paper feed roller 110 is stopped.
And the skew of the recording paper 108 is corrected. Next, the paper feed roller 110 starts rotating, and the recording paper 108 is fed to the transfer section. And in the transfer process,
The transfer device 111 transfers the toner image formed on the electrostatic latent image carrier 101 to the recording paper 108. The recording paper 108
Is conveyed to a fixing device 114 including a pressure roller 112 and a heat roller 113. In the subsequent fixing process, the heat of the heat generating roller 113 melts the toner 106, and the toner 106 permeates between the fibers of the recording paper 108 by the pressure action, so that the toner image is fixed on the recording paper 108. The recording paper 108 on which the toner image is fixed is ejected by the paper ejection roller 115.
To be sent out of the electrophotographic recording device.

On the other hand, the toner 106 remaining on the electrostatic latent image carrier 101 after the transfer passes between the charging device 102 and the electrostatic latent image carrier 101 as the electrostatic latent image carrier 101 rotates. The toner is carried by the toner carrier 105 of the developing device 104 and is removed at the same time. Therefore, the developing device 10
4, the charging polarity of the electrostatic latent image carrier 101 and the toner 10
Inverse development in which the polarity of 6 is the same is adopted, and a non-magnetic one-component contact developing method in which the toner carrier 105 and the electrostatic latent image carrier 101 are in contact, or a developer such as the toner 106 is an electrostatic latent image. A contact developing method such as a magnetic brush developing method of contacting with the carrier 101 is adopted. In particular, the toner carrier 1
When 05 is rotated at a speed higher than the peripheral speed of the electrostatic latent image carrier 101, good recording can be performed without causing an afterimage due to the residual toner 106.

By the way, the amount of the toner 106 passing between the charging blade 118 and the electrostatic latent image carrier 101 is 0.2 to 0.3 [mg / cm ² ] or less in the normal operation, and at the same time as the development. The removal method allowed us to continue recording without any problems. On the other hand, during an abnormal operation such as a jam of the recording paper 108, the entire amount of the toner 106 on the electrostatic latent image carrier 101 will pass between the charging blade 118 and the electrostatic latent image carrier 101. Immediately after that, neither charging nor exposure is sufficiently performed.

In this case, a voltage is applied to the charging blade 118 and the toner carrier 105, the exposure device 103 is turned off, and the electrostatic latent image carrier 101 is rotated several times as an initialization operation to carry the electrostatic latent image carrier. The body 101 can be sufficiently charged. In this way, an electric field is generated by the surface potential of the electrostatic latent image carrier 101 and the developing bias voltage, and the electrostatic force at that time causes the toner carrier 10
5 collects the toner 106 remaining on the electrostatic latent image carrier 101.

Next, the charging device 102 will be described.
FIG. 2 is a schematic view of a charging device used in the image forming apparatus showing the first embodiment of the present invention. In the figure, 102 is a charging device, which is a charging blade 11 that constitutes a charging member.
8 is supported by a metal guide 119,
Toner 10 with antinodes or edges remaining on the free end side
The electrostatic latent image carrier 101 is contacted or weakly pressed so that 6 can pass. A DC power supply 120 is provided between the guide 119 and the conductive support 101a of the electrostatic latent image carrier 101.
Is connected to the charging blade 118 via the guide 119.
A DC voltage is applied to.

In this embodiment, the voltage applied to the charging blade 118 by the DC power source 120 (hereinafter referred to as "applied voltage") has a negative polarity, which is a negative charging type electrostatic latent image. This is because the image carrier 101 is used, and the electrostatic latent image carrier 101 of positive charging type is used.
When using, the polarity of the applied voltage is positive.

Further, in the following description, the value of the applied voltage is −1.4 [kV], but the applied voltage is applied to the charging blade 118 as −1 to −1.6 [kV]. Therefore, the electrostatic latent image carrier 101 is set to −40.
It can be charged at 0 to -900 [V]. In this embodiment, the charging blade 118 has a short side length of 25.
[Mm], and the length of the long side was 250 [mm]. The length of the long side of the charging blade 118 is the electrostatic latent image carrier 101.
Of the photoconductive layer 101b in the longitudinal direction. Due to the manufacturing of the electrostatic latent image carrier 101, it is difficult to form the photoconductive layer 101b on the circumference of both ends in the longitudinal direction. Therefore, the length of the long side of the charging blade 118 is made slightly shorter than the length of the photoconductive layer 101b in the longitudinal direction so that the current does not leak from the DC power source 120 to the electrostatic latent image carrier 101.

The charging blade 118 is fixed to the guide 119 with a conductive double-sided tape.
The tape is not limited to the electrically conductive double-sided tape, and any electrically conductive double-sided tape may be used. The charging blade 118 is made of, for example, rubber material such as butyl rubber, chloroprene rubber, urethane rubber, silicone rubber, nitrile rubber, styrene rubber, butadiene rubber, carbon,
It is formed by adding conductive powder such as graphite, ferrite, aluminum powder, copper powder, bronze powder, stainless steel powder, titanium oxide and tin oxide, metal powder, metal fiber, etc., and has a volume resistance value of 10 ⁶ to 10 ¹³ [. Any blade can be used as long as it is [Ω-cm].

Further, the charging blade 118 is preferably an elastic body so that it can uniformly contact the electrostatic latent image carrier 101, and the thickness of the rubber material when a rubber material is used. Is preferably in the range of 0.5 to 5 [mm]. Next, a second embodiment will be described in which the charging blade has a two-layer structure of a conductive layer and a resistance layer.

FIG. 3 is a schematic view of a charging device used in an image forming apparatus showing a second embodiment of the present invention. In the figure, 102 is a charging device, and a charging blade 123 constituting a charging member is formed of a conductive layer 121 and a resistance layer 122. The charging blade 123 is supported by an insulative guide 124, and is contacted or weakly pressed against the electrostatic latent image carrier 101 on the free end side of the resistance layer 122 so that the toner 106 with an antinode or an edge can pass through. .
A DC power supply 120 is connected between the conductive layer 121 of the charging blade 123 and the conductive support 101a of the electrostatic latent image carrier 101, and a DC voltage is applied to the charging blade 118 via a guide 119. The polarity of the voltage applied to the conductive layer 121 of the DC power source 120 is negative because the negative charging type electrostatic latent image carrier 101 is used, and the positive charging type electrostatic latent image carrier is used. When the body 101 is used, the conductive layer 12 of the DC power supply 120 is used.
The polarity of the applied voltage with respect to 1 is positive.

As the conductive layer 121 of the second embodiment, any of those having a volume resistance value of 1.0 × 10 ⁴ [Ω-cm] or less can be used. For example, S
K steel, stainless steel, phosphor bronze, copper, nickel silver, beryllium copper, etc., a thin metal plate having elasticity of 10 to 1000 [μm] and a volume resistance value of 1.0 × 10 ⁴ [Ω-cm] or less. In order to obtain a uniform contact width in the longitudinal direction with the electrostatic latent image carrier 101, a conductive rubber having a rubber hardness of 90 ° [JIS A] or less, for example, butyl rubber, chloroprene rubber, urethane rubber, silicone Rubber materials such as rubber, nitrile rubber, styrene rubber, butadiene rubber, carbon,
Graphite, ferrite, aluminum powder, copper powder, bronze powder, stainless powder, titanium oxide, conductive powder such as tin oxide, metal powder, blades formed by adding metal fibers, polyimide, polyamide, polyester, polystyrene, Carbon, graphite, ferrite, aluminum powder, copper powder, bronze powder, soft polymer film made of resin such as polycarbonate and fluororesin,
Conductive powder such as stainless steel powder, titanium oxide, tin oxide,
What added the metal powder, metal fiber, etc. can be used.

Further, the resistance layer 122 of the charging blade 123
Are, for example, rubber sheets such as butyl rubber, chloroprene rubber, urethane rubber, silicone rubber, nitrile rubber, styrene rubber, butadiene rubber, fluorine rubber, ethylene propylene rubber, vinyl chloride, cellulose, polyimide, polyamide, polyester, polystyrene, polycarbonate, Conductive powder such as carbon, graphite, ferrite, aluminum powder, copper powder, bronze powder, stainless steel powder, titanium oxide, tin oxide, etc. on soft polymer film made of resin such as fluororesin, metal powder, metal fiber, etc. Conductive fibers, etc. are added to adjust the volume resistance value to 10 ⁶ to 1
Any of 0 ¹³ [Ω-cm] can be used. Further, in order to obtain a uniform contact width in the longitudinal direction with the electrostatic latent image carrier 101, the rubber hardness is 90
° [JIS A] or less.

In the experiment, a thin stainless plate having a thickness of 100 μm was used as the conductive layer 121, and
Carbon added to urethane rubber has a volume resistance of 1.0
× 10 ⁸ [Ω-cm], rubber hardness 60 ° [JIS
A], thickness 2.0 [mm], short side length 25 [m
m], and a conductive rubber sheet having a long side length of 250 [mm] was used as the resistance layer 122.

In addition, aluminum foil, copper foil, etc.
Metal foil and volume resistance value is 1.0 × 10 ^Four[Ω-cm] or less
A conductive tape or the like is attached to the resistance layer 122.
The resistance layer 122 by plating with various metals,
Conductive layer 121 is formed by applying patterning, thick film printing, etc.
You may. Further, the charging blade 123 carries an electrostatic latent image.
Small enough to be able to come into contact with the body 101 or weakly press it
At least one of the conductive layer 121 and the resistance layer 122 has an elastic property.
Any body is acceptable.

Next, a third embodiment of the present invention will be described. FIG. 4 is a schematic view of a charging device used in an image forming apparatus showing a third embodiment of the present invention. In the figure, 1
Reference numeral 02 is a charging device, 101 is an electrostatic latent image carrier, 101a is a conductive support, 101b is a photoconductive layer, 120 is a DC power source, 121 is a conductive layer, 122 is a resistive layer, 123 is a charging blade, and 124 is a guide. Is.

Even if the charging blade 123 is attached to the electrostatic latent image carrier 101 by changing the direction of trailing as shown in FIG. 3 from the direction of counter as shown in FIG. It is possible to obtain the same charging characteristics as in. Next, a fourth embodiment of the present invention will be described. FIG. 5 is a schematic view of a charging device used in an image forming apparatus showing a fourth embodiment of the present invention.

In the figure, 102 is a charging device, and in this case, a conductive rubber roller 126 is used as a charging member. The conductive rubber roller 126 is formed by covering the conductive shaft 127 with a rubber resistance layer 128. The conductive shaft 127 is a metal shaft such as stainless steel, steel, and aluminum.
7, a DC power source 120 is connected between the conductive support 101a of the electrostatic latent image carrier 101, and a DC voltage is applied to the charging blade 118 via a guide 119.

The rubber resistance layer 128 is made of rubber material such as butyl rubber, chloroprene rubber, urethane rubber, silicone rubber, nitrile rubber, styrene rubber, butadiene rubber, fluororubber, ethylene propylene rubber, carbon, graphite, ferrite, etc. Aluminum powder, copper powder, bronze powder, stainless steel powder, conductive powder such as titanium oxide and tin oxide, conductive powder such as metal powder and metal fiber, etc. are added to give a volume resistance value of 10 ⁶ to 10 ¹³ [Ω- cm]
Any of the above can be used.
Further, in order to obtain a uniform contact width in the longitudinal direction with the electrostatic latent image carrier 101, the rubber hardness is 90 ° [JIS A].
Below.

Further, similarly to the first to third embodiments, the electrostatic latent image carrier 101 and the conductive rubber roller 126 are brought into contact with or weakly pressed to the extent that the residual toner 106 can pass through. In addition, the conductive rubber roller 126
Is a direction (arrow b direction) following the rotation direction of the electrostatic latent image carrier 101 by a drive system (not shown),
Alternatively, the same direction as the rotation direction of the electrostatic latent image carrier 101 (arrow c
Direction). Also, it can be fixed so as not to rotate. When the conductive rubber roller 126 is rotated in the copying direction, the peripheral speed of the electrostatic latent image carrier 101 and the conductive rubber roller 126 are increased.
The peripheral velocities may be different or the same. In particular, when the peripheral speed of the electrostatic latent image carrier 101 and the peripheral speed of the conductive rubber roller 126 are the same, the conductive rubber roller 126 does not become a rotational load of the electrostatic latent image carrier 101.

In the first to third embodiments, the charging device 10 is used.
Charging blades 118 (FIG. 1) and 12 as the second charging member.
3 (FIG. 3) and conductive rubber roller 126 (FIG. 5)
However, it is limited only to these shapes.
Instead of using a charging brush, charging belt, etc.
The volume resistance value of the portion in contact with the latent image carrier 101 is 10 ⁶
-10¹³If it is constructed in the range of [Ω-cm]
Good. Also, the arrangement method is not limited to this.
However, various changes are possible.

Various changes can be made as long as the toner 106 can be contacted or weakly pressed against the latent electrostatic image bearing member 101 so that the residual toner 106 can pass through. In the case of this embodiment, the polarity of the toner 106 is negative, and a negative voltage is applied to the charging blades 118 and 123 and the conductive rubber roller 126. Therefore, the toner 106 of negative polarity is electrically charged to the charging member. It is difficult for the toner to adhere, and it is possible to prevent the toner 106 from sticking to the charging member, and it is possible to maintain good charging characteristics of the charging member for a long period of time.

By the way, if recording is performed for a long period of time, foreign matter may adhere to the charging member, and the electrostatic latent image carrier 101 may not be charged. When the foreign matter adhering to the charging member is examined, the toner 106 charged to the positive polarity, the external additive, the charge control agent, the internal additive contained in the toner 106 charged to the positive polarity, etc. Positively charged toner, etc. ”).

Then, as long as the positively charged toner or the like is attached to the area A of FIG. 2 in contact with the electrostatic latent image carrier 101 of the charging member and before and after the area A, the charging member attaches the electrostatic latent image carrier 101. Although it can be charged, if the positively charged toner or the like adheres to the area A, the electrostatic latent image carrier 101 cannot be charged. Next, the cause of formation of positively charged toner and the like will be described.

FIG. 6 is a sectional view of a non-magnetic one-component contact type developing device. In the figure, 105 is a toner carrier, 13
0 is a toner layer thickness regulating member, 131 is a toner supply roller,
132 is a toner hopper. The toner hopper 132 contains the toner 106, and the toner hopper 1
A toner supply roller 131 is disposed below the inside of 32. The toner supply roller 131 has an elastic surface layer formed by covering a conductive support such as a metal core with a foaming agent such as urethane foam. The surface of the toner supply roller 131 is always toner 106. Is covered.

When the toner supply roller 131 is rotated in the direction of arrow d (counterclockwise), the toner 106 is conveyed to the toner carrier 105 provided in contact with the toner supply roller 131 in accordance with the rotation. To be done. The conveyed toner 106 comes into contact with the toner carrier 105 and the toner supply roller 131 and is charged by being rubbed,
The electrostatic force generated by the developing bias voltage of the DC power supply 134 connected between the toner carrier 105 and the toner supply roller 131 moves to the toner carrier 105 and the toner 10
The toner carrier 105 is generated by the self-image force of the charge of 6.
After being attached to the surface of the toner carrier, the toner is conveyed through the toner carrier 105 that rotates in the direction of arrow e (counterclockwise).

A toner layer thickness regulating member 130 is provided on the downstream side where the toner 106 is conveyed, and a uniform thickness of one to two particles of the toner 106 is provided on the toner carrier 105. Is formed, the toner 106 is further charged by friction with the toner layer thickness regulating member 130. The toner 106 attached to the toner carrier 105 is conveyed to the electrostatic latent image carrier 101 provided in contact with the toner carrier 105, and the electrostatic latent image carrier 10 is transferred.
The toner image corresponding to the electrostatic latent image on the toner carrier 1
05 and the conductive support 101a of the electrostatic latent image carrier 101 are developed by the developing bias voltage of the DC power supply 133 connected. The toner 106 that does not contribute to the development is again conveyed to the toner supply roller 131 and collected.

In this embodiment, the toner carrying member 105 is the electrostatic latent image carrying member 101 with a uniform pressure contact force over the entire length in the longitudinal direction.
It is also necessary to have the property of being a developing electrode in the vicinity of the surface layer part in contact with the surface layer part. Therefore, for example, a conductive rubber such as a metal core is coated around the conductive support to form an elastic electric resistance layer, and an insulating layer is thinly applied thereon.

As the conductive rubber, any rubber material such as chloropyrene rubber, nitrile rubber, urethane rubber can be used, and a conductive additive such as conductive carbon black is added thereto. Further, the toner bearing member 105 is brought into contact with the electrostatic latent image bearing member 101 with a uniform pressure contact force over the entire length in the longitudinal direction, and a certain contact width is required. Therefore, the rubber hardness is set to 60 ° [JIS A] or less. .

Since the insulating layer is applied on the conductive rubber, it has elasticity enough to follow the displacement of the conductive rubber when it is pressed against the electrostatic latent image carrier 101. It is necessary to have, and urethane-based paint, silicone rubber-based paint, etc. correspond to this. Toner carrier 10
Explaining the example of 5 in terms of specifications, a chloroprene rubber having a rubber hardness of 30 ° [JIS A] and a volume resistance value of 10 ⁴ [Ω-cm] is coated around a metal core having a diameter of 8 [mm], A urethane-based paint is applied thereon to a thickness of about 20 to 100 [μ] to give a final finished outer diameter of about 20 [mm] and a surface layer roughness of 0.5 to 5 [μRZ]. In this case,
Although the toner carrier 105 has a three-layer structure, it may have a two-layer structure in which the elastic electric resistance layer of the conductive support is covered.

On the other hand, the toner 106 is the electrostatic latent image carrier 1.
Since 01 has a negative charge polarity, a styrene-based or polyester-based resin was filled with a negative charge type charge control agent (10), and a non-magnetic material having a diameter of about 9 to 12 [μm] was used. . Then, due to the friction between the toner supply roller 131 and the toner carrier 105, the toner 106 interposed therebetween is charged to a negative polarity and adheres to the toner carrier 105. Further, as the toner 106, it is possible to use a toner having magnetism obtained by adding magnetic powder such as iron and ferrite to resin.

Further, urethane type rubber is used as the toner layer thickness regulating member 130 to make the thickness of the toner 106 on the toner carrier 105 uniform and uniform, and further charged. Good recording can be obtained by using a metal thin plate made of stainless steel, phosphor bronze, etc. in addition to rubber, a polymer compound material such as nylon, polyester, etc., or a material obtained by coating the polymer compound on rubber, metal, etc. be able to.
When rubber is used, a thin layer of the toner 106 is uniformly and evenly attached on the toner carrier 105, and the rubber hardness is 40 to 9 in order to perform optimum charging by friction.
It is preferably 0 ° [JIS A].

If the electrostatic latent image carrier 101 is positively charged, the toner 106 is also positively charged. Since the developing device 104 has such a configuration, at the initial stage, the toner 106 in the developing device 104 is the toner carrier 105 and the toner layer thickness regulating member 1.
The toner is charged to a negative polarity by 30 and the toner supply roller 131.

By the way, in the image forming apparatus of the present invention that does not use a cleaner, the toner 106 remaining after the transfer is collected by the developing device 104, and the toner 106 collected for effective use of the toner 106 is used. It is designed to be developed again. In this way, toner 1
When 06 is recycled, part of it is the developing device 10.
4, toner layer thickness regulating member 130, toner supply roller 1
31, the electrostatic latent image carrier 101, the charging member, and the like come into contact with each other for a long period of time. Such toner 106 is subjected to mechanical stress, and the external additive, charge control agent, internal additive, and the like forming the toner 106 are released from the toner 106, which is a positive polarity opposite to the desired polarity. The toner is charged in polarity, and the positively charged toner or the like is generated.

The positively charged toner or the like is the electrostatic latent image carrier 1 which is not irradiated with light from the exposure device 103 (FIG. 1).
01 is transferred from the developing device 104 to the non-image portion and is normally developed. Further, the positively charged toner and the like are conveyed to the charging device 102 as the electrostatic latent image carrier 101 rotates. In the charging device 102, the electrostatic latent image carrier 1
A negative voltage is applied to the charging member to charge 01, and an electric field is generated between the electrostatic latent image carrier 101 and the charging member.

As a result, it is considered that positively charged toner or the like electrostatically adheres to the charging member, becomes foreign matters, and rubs against the electrostatic latent image carrier 101 for a long period of time, and eventually sticks. . The number of recording sheets, that is, the service life until the above-mentioned positively charged toner or the like is fixed to the charging member and causes the charging failure, changes depending on the composition, configuration, etc. of the toner 106 used, and causes the charging failure at 3000 sheets, 10,000 sheets However, there are some that do not cause poor charging.

Next, the refresh operation for removing the positively charged toner and the like adhering to the charging member from the charging member and extending the life of the charging member will be described. This refresh operation is performed during non-recording. In performing the refresh operation, an electric field for electrostatically transferring positively charged toner or the like to the electrostatic latent image carrier 101 is formed between the electrostatic latent image carrier 101 and the charging member. Further, an electric field for electrostatically transferring the positively charged toner or the like transferred to the electrostatic latent image carrier 101 to the toner carrier 105 is formed between the electrostatic latent image carrier 101 and the toner carrier 105. Then, an electric field for electrostatically transferring the positively charged toner or the like transferred to the toner carrier 105 to the toner supply roller 131 is applied to the electrostatic latent image carrier 101 and the toner carrier 105.
Form in between.

In this state, the electrostatic latent image carrier 10
1, toner carrier 105 and toner supply roller 131
Between the electrostatic latent image carrier 101 and the charging member in the area A (FIG. 2) and the developing area B in which the electrostatic latent image carrier 101 and the toner carrier 105 or the toner 106 are in contact. It is rotated by an angle equal to or greater than the distance L in the rotation direction. By doing so, the positively charged toner or the like attached to the charging member can be electrostatically transferred from the electrostatic latent image carrier 101, via the toner carrier 105, to the toner supply roller 131 and collected.

Next, a specific refresh operation will be described with reference to FIG. FIG. 7 is an explanatory diagram of potentials.
First, the voltage applied from the DC power source 120 to the charging member is changed to change the potential of the charging member from −1.4 [kV] at the time of recording to a high positive potential (eg, +1 [kV]).
Further, the voltage applied from the DC power supply 133 to the toner carrier 105 is changed to change the potential of the toner carrier 105 to −4 at the time of recording.
High potential from 00 [V] to the minus side (for example, -1.1
[KV]).

Then, the voltage applied from the DC power supply 134 to the toner supply roller 131 is changed, and the toner supply roller 13 is changed.
The potential of No. 1 is changed from -200 [V] at the time of recording to a high negative potential (for example, -600 [V]). And
The electrostatic latent image carrier 101, the toner carrier 105, and the toner supply roller 131 were rotated by the amount of one revolution of the electrostatic latent image carrier 101.

As a result, the positively charged toner and the like adhering to the charging member can be electrostatically removed from the charging member and further electrostatically transferred to the toner supply roller 131 to be collected. Further, the potential difference between the member to which the positively charged toner and the like are attached and the member to which the positively charged toner and the like are transferred is at least 200 [V] from various experiments.
The above was necessary.

The refresh operation is performed by the exposure apparatus 1.
03 was not operated, but the electrostatic latent image carrier 101 was exposed to the whole surface by the exposure device 103, and the electrostatic latent image carrier 101 was exposed.
By lowering the surface potential of the toner carrier 105
Also, the refresh operation could be performed by setting the voltage applied to the toner supply roller 131 to the same voltage as during recording. Further, the electric field forming means for electrostatically removing the positively charged toner and the like adhering to the charging member is not limited to the above-mentioned means. For example, instead of changing the potential of the charging member to a positive potential (for example, +1 [kV]), the potential of the charging member is set to −1.4 [kV] to uniformly charge the electrostatic latent image carrier 101. After that, even if the potential of the charging member was changed from -1.4 [kV] to 0 [V] (GND), it was similarly good.

As described above, in order to remove the positively charged toner and the like adhering to the charging member, an electric field having a polarity opposite to that at the time of recording is generated between the charging member and the electrostatic latent image carrier 101.
Positively charged toner or the like is transferred from the charging member to the electrostatic latent image carrier 10
It may be transferred to 1. Further, the method and place for collecting the positively charged toner and the like removed from the charging member are not limited to those described above. For example, a conductive roller is provided in contact with the electrostatic latent image carrier 101 to provide a roller transfer device, and the toner image on the electrostatic latent image carrier 101 is recorded on the recording paper 108.
It is also possible to apply a negative voltage to the roller transfer device, transfer the positively charged toner and the like removed from the charging member to the transfer roller, and collect with a blade or the like. As described above, it is possible to variously change the collecting method and the collecting place of the positively charged toner and the like.

By the way, the positively charged toner or the like removed from the charging member is supplied to the toner supply roller 131 of the developing device 104.
In the method of collecting the toner, the positively charged toner and the like can be removed from the electrostatic latent image carrier 101 by changing the potential of the toner carrier 105 to a higher negative potential, but at the same time, the toner on the toner carrier 105 becomes negative. The toner 106 charged in the negative direction is transferred to the electrostatic latent image carrier 101.

Therefore, as in the case of the abnormal operation such as the jam of the recording paper 108 as described above, the voltage for recording is applied to the charging member and the toner carrier 105 to expose the exposure device 103.
The toner 106 transferred onto the electrostatic latent image carrier 101 is sufficiently charged by rotating the electrostatic latent image carrier 101 several times as an initializing operation in a state in which the electrostatic latent image carrier 101 is not operated. The toner carrier 10
5 can be collected.

In this case, when the electrostatic latent image carrier 101 is rotated several times, the electrostatic latent image carrier 101 is charged by the charging member, while the toner is higher than the surface potential of the electrostatic latent image carrier 101. Since the potential of the carrier 105 is increased to the positive side, the negatively charged toner 106 is transferred to the toner carrier 105. Next, the timing of performing the refresh operation and the initialization operation will be described.

Generally, in the electrophotographic recording apparatus, various sensors and the like are checked when the main power is turned on, so that the refresh operation and the initialization operation can be performed after the checking operation is completed. Further, the refresh operation and the initialization operation can be performed before the recording is started or after the recording is completed.

Since the electrophotographic recording apparatus generally has a function of counting the number of recorded sheets, it is, for example, 500
It is also possible to perform the refresh operation and the initialization operation for each set number of recorded sheets, such as 2000 sheets, 2000 sheets, or 5000 sheets. Furthermore, the refresh operation and the initialization operation can be performed by combining these timings.

Further, the refresh operation and the initialization operation are not limited to those performed only once, and for example, the refresh operation, the initialization operation, the refresh operation, and the initialization operation are repeated to make a total of 4 operations.
The refresh operation, the refresh operation, and the initialization operation may be repeated three times in total, or the refresh operation, the initialization operation, and the initialization operation may be repeated three times in total.

Although only the DC voltage is applied to the charging member during recording, the DC voltage and the AC voltage can be superimposed and applied to the charging member. The present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the spirit of the present invention.
They are not excluded from the scope of the invention.

[0068]

As described in detail above, according to the present invention, an electrostatic latent image carrier for carrying an electrostatic latent image is provided.
A charging device is provided in contact with the electrostatic latent image carrier. The charging device charges the electrostatic latent image bearing member while generating an electric field between the charging device and the electrostatic latent image bearing member and passing the toner remaining on the electrostatic latent image bearing member.

An exposure device is also provided to expose the charged surface of the electrostatic latent image carrier to form an electrostatic latent image. Then, the developing device forms a toner image corresponding to the electrostatic latent image on the electrostatic latent image carrier on the surface of the electrostatic latent image carrier. Further, the transfer device transfers the toner image formed on the surface of the electrostatic latent image carrier onto the final recording medium, and the fixing device fixes the toner image transferred onto the final recording medium onto the final recording medium. After the transfer device transfers the toner image to the final recording medium, the toner remains on the electrostatic latent image carrier, but the toner remains on the electrostatic latent image carrier and passes through the charging device. And reaches the developing device, and is collected by the developing device.

Therefore, since a cleaner is unnecessary,
The image forming apparatus can be downsized, and it is not necessary to discard the collected toner, so that the maintenance work can be simplified. Also, almost 100% of toner
[%] Since it can be used, running cost can be reduced. The charging device generates an electric field with the electrostatic latent image carrier during recording, but generates an electric field having a polarity opposite to the polarity during non-recording. Therefore, the toner adhering to the charging member of the charging device is collected by the electrostatic latent image carrier, so that a good image can be stably recorded for a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic recording apparatus showing a first embodiment of the present invention.

FIG. 2 is a schematic view of a charging device used in the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a schematic view of a charging device used in an image forming apparatus showing a second embodiment of the present invention.

FIG. 4 is a schematic view of a charging device used in an image forming apparatus showing a third embodiment of the present invention.

FIG. 5 is a schematic view of a charging device used in an image forming apparatus showing a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view of a non-magnetic one-component contact type developing device.

FIG. 7 is an explanatory diagram of potentials.

[Explanation of symbols]

 Reference Signs List 101 electrostatic latent image carrier 102 charging device 103 exposure device 104 developing device 106 toner 108 recording paper 111 transfer device 114 fixing device

Claims (2)

[Claims] 1. An electrostatic latent image bearing member carrying (a) an electrostatic latent image bearing member, and (b) being provided in contact with the electrostatic latent image bearing member, between the electrostatic latent image bearing member. A charging device for charging the electrostatic latent image carrier while generating an electric field and allowing the toner remaining on the electrostatic latent image carrier to pass through; (c) the electrostatic latent image carrier is charged. An exposure device that exposes the surface to form an electrostatic latent image, and (d) forms a toner image corresponding to the electrostatic latent image on the electrostatic latent image carrier on the surface of the electrostatic latent image carrier. With
A developing device for collecting the toner remaining on the electrostatic latent image carrier and having passed through the charging device; and (e) a toner image formed on the surface of the electrostatic latent image carrier as a final recording medium. An image forming apparatus comprising: a transfer device that transfers the toner image onto the final recording medium; and (f) a fixing device that fixes the toner image transferred onto the final recording medium onto the final recording medium. 2. The image forming apparatus according to claim 1, further comprising means for generating an electric field having a polarity opposite to that of the electric field generated between the electrostatic latent image carrier and the charging device during recording during recording.