JP2889034B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus for forming an image by forming a toner image on the surface of a photosensitive drum and then transferring and fixing the toner image on a transfer material.

[0002]

2. Description of the Related Art Conventionally, the Carlson process method has been widely used in the above electrophotographic apparatus. In this method, for example, as shown in FIG. 11, the surface of a photosensitive drum 31 having a photoconductive layer whose surface is exposed to light and whose resistance value decreases is uniformly charged by a charger 32 by corona discharge in a dark place. Next, the exposure is performed by the exposure device 33 in accordance with the image to be copied, thereby removing the charged electric charge in the light-irradiated portion to form an electrostatic latent image.

[0003] Next, a toner 39 charged to the opposite polarity to the charge on the photosensitive drum 31 in the developing device 34 is adhered to the electrostatic latent image to form a visible image by the toner 39. . Then, transfer material 4 such as paper
The above visible image is transferred and fixed on the image No. 0. On the other hand, after the electrostatic latent image on the photosensitive drum is neutralized by the light of the neutralizer 38, the process starting from charging by the charger 32 is repeated again, and continuous image formation is performed.

In the electrophotographic system to which the Carlson process is applied as described above, a corona discharger is usually used as a charger 32 for charging a photosensitive drum 31. In this corona discharger, the applied voltage is several k.
In addition to requiring a high voltage of V, it is easily affected by environmental changes such as a change in the amount of charge on the surface of the photosensitive drum 31 due to a temperature change. In addition, ozone is generated during corona discharge, which causes environmental health problems.

Therefore, for example, Japanese Patent Publication No. 2-4900 discloses an image forming method which does not require corona charging as described above. In the method, as shown in FIG. 12, a columnar photoconductor 50 is formed on a transparent substrate 51 such as glass, a transparent conductive layer 52 made of In ₂ O ₂ or the like, a photoconductive layer 53 made of Se or the like, An insulating layer 54 made of a polyethylene terephthalate film, variylene, or the like is sequentially laminated.

In the above-described configuration, the magnet 56 serving as a toner holder having conductive magnetic toners 55 attached thereto as a magnetic brush is brought close to the surface of the photoconductor 50, and the transparent conductive layer 52 of the photoconductor 50 is provided. When the conductive magnetic toner 55... Slides on the surface of the photoreceptor 50 while a voltage is applied between the conductive magnetic toner 55 and the magnet 56, the surface of the conductive magnetic toner 55
Are charged to the same polarity as.

When the photoconductor layer 53 is exposed from the transparent substrate 51 side while the surface of the photoconductor 50 is charged in such a manner, the resistance of the photoconductor layer 53 is reduced at the light irradiation part, The electric charge is injected to below the insulating layer 54, so that the surface of the photoconductor 50 corresponding to the exposed portion has the electric charge of the opposite polarity to the conductive magnetic toner 55.

As a result, in the above configuration, the surface portion of the photosensitive member 50 corresponding to the exposed portion and the toner 55 form a pair of charges having opposite polarities, and thus are brought into a state of attracting each other. For this reason, only the toner 55 in the above-mentioned exposure area remains on the surface of the photoconductor 50 even if the magnet 56 is moved away from the photoconductor 50 thereafter. As described above, a toner image can be formed on the surface of the photoconductor 50 without using corona charging.

After the toner image is formed on the surface of the photoreceptor 50 as described above, the toner image is transferred from the surface of the photoreceptor 50 to the surface of the transfer material in the same manner as in the Carlson process. By sending the image to a fixing device that heats and fixes the image, a permanent image can be formed on the transfer material.

[0010]

However, in the charging of the surface of the photoconductor 50 in the above-described conventional configuration, an applied voltage for charging the surface of the photoconductor 50 to a predetermined potential via the toner 55 is applied in one step. Since the contact time between the photosensitive member 50 and the toner 55 is short, the surface potential of the photosensitive member 50 is not sufficiently increased with respect to a rise in the potential of the leading end portion of the toner 55, but is instantaneously increased by the applied voltage. A potential difference occurs between the tip of the photoconductor 55 and the surface of the photoconductor 50.

Therefore, the potential difference between the photosensitive members 5
A force is generated between the surface of the photoconductor 50 and the charged toner 55, and the toner 55 moves to the surface of the unexposed photosensitive member 50 against the magnetic force of the magnet 56. is there. Therefore, in the above configuration, there is a problem that the toner 55 is transferred onto the transfer material, the fog density on the transfer material is increased, and the transferred image becomes unclear.

[0012]

In order to solve the above-mentioned problems, the electrophotographic apparatus of the present invention has a photoconductor in which a photoconductor layer, a transparent conductive layer, and a transparent support are sequentially stacked from the surface side. When a built-in magnet, to expose a magnetic toner having a conductivity and toner carrier supplied to the surface of the photosensitive member, the upper Kikoshirube collector layer through the upper Symbol transparent support and the transparent conductive layer exposed and means, between the toner holding member and the transparent conductive layer
Applying a voltage between the magnetic toner and the surface of the photoreceptor
Is brought into sliding contact with the
Charged to the same polarity as the magnetic toner,
Exposing the sliding contact portion with the conductive toner by the above-mentioned exposure means
As a result, the visible image of the magnetic toner
Forming a, in an electrophotographic apparatus for transferring and fixing the transfer material a visible image of the magnetic toner, the magnetic toner and the photosensitive
It is characterized in that a control means is provided for increasing the voltage applied between the toner holding member and the transparent conductive layer in multiple stages when the sliding contact is made with the surface of the body .

[0013]

According to the above construction, a voltage is applied between the toner holder and the transparent conductive layer, and the magnetic toner having conductivity slides on the surface of the photoconductor, so that the surface of the photoconductor becomes magnetic. It is charged to the same polarity as the tip of the toner. At the time of such charging, the photoconductor layer functions as a kind of capacitor between the magnetic toner in sliding contact and the surface of the photoconductor, and each has a capacitance. Has a time constant, so that a time delay occurs before the surface of the photoconductor reaches the same potential as the magnetic toner, and a potential difference occurs between the magnetic toner and the surface of the photoconductor during charging.

Conventionally, the application of a predetermined voltage between the toner holding member and the conductive layer is performed in one step, so that the above-mentioned potential difference sometimes becomes large. In some cases, the amount of toner sucked and adhered to the surface portion becomes large, so that the fog density on the transfer material becomes high, and the image becomes unclear.

However, in the above-mentioned configuration, when charging is applied between the toner holder and the transparent conductive layer, control means for increasing the applied voltage to the predetermined voltage in multiple steps is provided. Therefore, the voltage applied first can be set lower than in the prior art, so that the potential difference generated between the magnetic toner and the surface of the photoreceptor is reduced.

Therefore, the attractive force between the magnetic toner and the surface of the photoreceptor due to such a potential difference can be reduced, while the magnetic force between the magnet of the toner holder and the magnetic toner is maintained. It is possible to reduce the unexpected amount of toner adhered to the surface of the photoreceptor that has not been cleaned.

After the potential of the surface of the photoreceptor substantially rises to the potential of the toner holder in this manner, subsequently, the voltage applied between the toner holder and the transparent conductive layer is stepwise increased. By doing so, it is possible to increase the applied voltage between the toner holder and the transparent conductive layer to a predetermined voltage in accordance with an increase in the potential of the photoconductor. Therefore, the surface potential of the photoconductor can be increased to a predetermined potential while maintaining a small potential difference between the magnetic toner and the surface of the photoconductor.

[0018]

1 to 10 show an embodiment of the present invention.
This will be described below. As shown in FIG. 1, the electrophotographic apparatus of this embodiment includes a cylindrical photosensitive drum (photoconductor) 1 that can rotate clockwise in the apparatus. On the right side of the photosensitive drum 1, a substantially cylindrical developing sleeve (toner holding member) 3 as a developing device, an exposing device (exposure means) 2 in the photosensitive drum 1, and
Transfer belts 22 are disposed above the photosensitive drums 1 respectively.

As shown in FIG. 4, the photosensitive drum 1 has a transparent substrate 103 made of optically transparent glass or the like, and a transparent support made of a sputtered film such as In ₂ O ₃ or SnO ₂ formed on the surface of the transparent support 103. Conductive layer 102, Se, ZnO, CdS, or amorphous
A photoconductive layer 101 made of a photoconductive material such as Si is sequentially laminated. In this embodiment, a 0.5 μm thick In ₂ O ₃ layer is formed as the transparent conductive layer 102, and a 3 μm thick amorphous layer is formed as the photoconductive layer 101.
A Si layer is formed.

As shown in FIG. 2, the developing sleeve 3 has a toner 5 having conductivity and magnetism as a developer.
Is stored in the toner tank 8 for storing the toner, and is close to the position facing the photosensitive drum 1 at the opening 8a of the toner tank 8,
The photosensitive drum 1 is provided so as to extend along the longitudinal direction.

The developing sleeve 3 is made of non-magnetic material such as aluminum or martensitic stainless steel, and has a substantially cylindrical magnetic shape in which magnets of N polarity and S polarity are alternately arranged in the circumferential direction. A roller 4 is coaxially built in. Accordingly, the developing sleeve 3 holds the toner 5 on the surface of the developing sleeve 3 by an alternating magnetic field generated by the rotation of the magnetic roller 4 in, for example, a counterclockwise direction, and rotates the magnetic roller 4 in the rotating direction of the magnetic roller 4. The paper is conveyed in a clockwise direction opposite to the clockwise direction.

As shown in FIG. 1, a stirring roller 7 for stirring the stored toner 5 is rotatably provided in the toner tank 8, and a doctor blade 6 is provided at a position below the developing sleeve 3 in the opening 8a. Is installed. The doctor blade 6 adjusts the transport amount of the toner 5 held on the surface of the developing sleeve 3 and transported clockwise as described above to a predetermined amount.

As shown in FIG. 3, after the toner image on the photosensitive drum 1 is transferred to the transfer belt 22 by contacting with a transfer belt 22 described later, the toner 5 remaining on the photosensitive drum 1 is cleaned. A scraper 26 made of a flexible rubber or the like to be collected and collected may be provided above the developing sleeve 3.

The toner 5 having conductivity and magnetism is prepared by kneading a resin such as a styrene-acryl copolymer with a magnetic powder such as iron powder and ferrite and a coloring material such as carbon black, and pulverizing the resin. From several μm to several tens μ
m.

The exposure device 2 is constituted by an LED array (not shown) in which a light emitting diode and a short focus lens are combined, and is shown in FIG. 2 according to an image pattern signal from an exposure control device (not shown). As described above, the light is emitted toward the sliding contact portion of the toner 5 held by the developing sleeve 3 and rotating, that is, the direction of accumulation of the toner 5 formed upstream in the rotation direction of the photoconductor 1. The irradiation light is focused on the photoconductive layer 101 via the transparent support 103 and the transparent conductive layer 102 of the photosensitive drum 1 shown in FIG.

On the other hand, the transfer belt 22 shown in FIG.
It is formed in an endless belt shape using a film material mainly composed of a polyimide resin having excellent mechanical strength and high heat resistance, and is formed of a conductive elastic member disposed above the photosensitive drum 1. A transfer roller 14, a heating device 15, which will be described later, which is disposed slightly above the transfer roller 14 on the left side in the drawing, and a tension roller 21 which is further disposed below the heating device 15 on the left side below the transfer roller 14. They are wrapped around them so as to surround them from the outside.
As a result, the transfer belt 22 is sandwiched between the photosensitive drum 1 and the transfer roller 14 between the photosensitive drum 1 and the transfer roller 14.

The transfer belt 22 is made of a material
Although a film-like polyimide resin is used, the material is not particularly limited to this material, as long as the surface onto which the toner 5 is transferred has at least an insulating property as described later. A metal belt such as an electroformed nickel belt as a substrate may be provided with a fluorine coating.

Although the thickness of the transfer belt 22 is not particularly limited, it is preferably about 10 μm to 200 μm in consideration of thermal conductivity and mechanical strength, and the thickness of the transfer belt 22 should be such that the gloss of the image is moderate. For this purpose, the surface may be formed as a rough surface.

The heating device 15 is for heating and melting the toner 5 transferred to the surface of the transfer belt 22, as will be described later, and prints a Mo-based planar heating resistor 16 on an alumina ceramic substrate. Further, a ceramic heater is formed by printing and laminating a glass coat thereon. Therefore, the heating device 15 is configured to quickly raise the temperature to a predetermined heating temperature by energizing the heating resistor 16, and is arranged such that this heating surface is in direct contact with the surface of the transfer belt 22. Have been.

A pressure roller 17 that rotates while applying a pressing force in a direction toward the heating device 15 via the transfer belt 22 is disposed above the heating device 15. The pressure roller 17 is carried out from a transport guide plate 13 to be described later onto the transfer belt 22 and
The transfer paper (transfer material) P conveyed on the transfer belt 5 is sandwiched by a pressure contact portion with the transfer belt 22.

Further, as shown in FIG. 1, the electrophotographic apparatus includes a cooling fan 24 for cooling the transfer belt 22 from below, a main motor 23 which is a driving source of the apparatus, and The transport guide plate 13 for transporting the transfer paper P and a paper output unit 27 for discharging the transfer paper P from the inside of the apparatus are provided.

The transport guide plate 13 is disposed substantially horizontally above the photosensitive drum 1, the developing sleeve 3, and the transfer belt 22 to transfer the transfer paper P transported from the registration rollers 12. Is carried out onto the transfer belt 22 moving in the direction of the heating device 15. The transfer paper P sent to the registration roller 12 is conveyed from a paper feed actuator 10 and a paper feed roller 9 arranged near a transfer paper supply opening (not shown), and controls the rotation of the registration roller 12. A paper feed solenoid 11 is provided.

The paper output means 27 is disposed on the left side of the pressure contact portion between the transfer belt 22 and the pressure roller 17, and as its constituent members, the transfer / fixing belt 8 and the pressure roller 1
A paper output guide plate 19 which forms a paper output path connecting the pressure contact portion with the transfer paper discharge opening 2 to a transfer paper discharge opening (not shown);
A paper output actuator 18 is provided in the vicinity of a pressure contact portion between the paper output pressure plate 17 and the pressure roller 17, and a transport roller 20 is provided at the end of the paper output guide plate 19.

In the structure of the above embodiment, a predetermined voltage can be applied between the developing sleeve 3 and the transparent conductive layer 102 as shown in FIG. As shown in FIG. 1, there is provided a control means 25 for increasing the applied voltage stepwise according to the surface potential of the photoconductor 1 which rises as a result. As shown in FIG. 7, for example, the control unit 25 includes a plurality of relays corresponding to the number of stages in the applied voltage that changes in stages.
The voltage applied to the developing sleeve 3 can be increased in a stepwise manner by connecting the relays in parallel and opening and closing the relays sequentially using a timer or a microcomputer having a specific program set at a predetermined interval. And
As the other control means 25, it is also possible to use an attenuator or to electronically control the applied voltage.

Next, the operation of the electrophotographic apparatus having the above configuration shown in FIG. 1 will be described below.

First, 1 is supplied by transfer paper supply means (not shown).
When a sheet of transfer paper P is fed from the transfer paper supply opening,
When the leading end of the transfer paper P pushes up the paper feed actuator 10, a paper input detection switch (not shown) detects the supply of the transfer paper P, transmits a paper input detection signal to the main motor 23, and Is driven to rotate.

Thereafter, the rotation of the main motor 23 is transmitted to the paper feed roller 9 via a rotation transmission mechanism (not shown), whereby the paper feed roller 9 is rotated. The paper P is transported to the registration roller 12.

The transfer paper P conveyed to the registration roller 12 as described above is temporarily stopped by the rotation of the registration roller 12 controlled by the paper feed solenoid 11. At this time, each paper feed roller 9
9 shows a state in which the rear end side of the transfer paper P is sandwiched and the resistance of the roller surface is small, so that the transfer paper P slips on both sides due to the stoppage of the transfer of the transfer paper P. I have.

Here, the electrophotographic apparatus enters a standby state,
If the print start signal is not generated within a predetermined time, the main motor 23 stops. On the other hand, when a print start signal is generated in the standby state, all the rotation units other than the registration roller 12 are rotated by the rotation transmission mechanism.

Next, FIG. 1, FIG. 2, and FIG.
The developing process of the toner 5 will be described based on 0. First, as shown in FIG. 2, the alternating magnetic field generated by the rotation of the magnetic roller 4 in the counterclockwise direction
As shown in (1), the magnetic brush is formed while being held on the surface of the developing sleeve 3, and is conveyed in the clockwise direction B on the surface of the developing sleeve 3. On the other hand, the photosensitive drum 1 is transported in the clockwise direction A. Therefore, the developing sleeve 3 and the photosensitive drum 1 rotate in mutually opposite directions in the vicinity thereof.

At this time, since the photosensitive drum 1 and the developing sleeve 3 are disposed close to each other, the sliding contact between the photosensitive drum 1 and the toner 5 causes a gap between the developing sleep 3 and the transparent conductive layer 102. The toner 5 charged by the voltage applied to the photosensitive drum 1 is naturally conveyed toward the upstream portion of the photosensitive drum 1 in the traveling direction, and the toner 5 reservoir shown in FIG. 2 is formed.

At this time, when the toner 5 slides on the surface of the photosensitive drum 1, the surface of the photosensitive drum 1 is charged to the same polarity as the toner 5. Such a charging operation is repeated several times around the photosensitive drum 1 and the sliding with the toner 5 is repeated, so that the surface potential of the entire photosensitive drum 1 becomes
The potential is substantially the same as that of the developing sleep 3. Therefore, the toner 5
The toner 5 does not adhere to the photosensitive drum 1 in a portion where the surface of the photosensitive drum 1 is separated from the photosensitive drum 1 because the toner 5 is mainly affected by the magnetic force by the magnetic roller 4.

In such charging, the rate of increase in the surface potential of the photosensitive drum 1 when the photosensitive drum 1 makes one rotation via the toner 5 depends on the electrical characteristics of the toner 5 and the transparency of the photosensitive drum 1. It is determined by the electric characteristics of the conductive layer 102 and the photoconductor layer 101, the transport speed of the toner 5, and the rotation speed of the photosensitive drum 1. That is, as shown in the schematic diagram of FIG. 10A, the photosensitive drum 1, the toner 5, and the developing sleeve 3 can be considered as a kind of capacitor.
The equivalent circuit is as shown in FIG.

Therefore, when a voltage is applied to such an equivalent circuit, the potential rise at a minute portion on the surface of the photosensitive drum 1 shown in FIG. 4, that is, the potential between C ₂ and C ₃ in the equivalent circuit becomes During the sliding time of the toner 5, the voltage does not rise to the applied voltage. Next, when the photosensitive drum 1 rotates one revolution and the toner 5 slides on the minute portion, The potential rises. By repeating this process,
As shown in FIG. 9, the surface potential of the photoreceptor drum 1 rises almost stepwise to the applied potential.

Therefore, in the configuration of the above embodiment, the control means 25 shown in FIG. 1 applies the voltage between the transparent conductive layer 102 and the developing sleeve 3 shown in FIG. The voltage is divided into n (positive integer) steps and raised at predetermined time intervals.

That is, the surface potential of the photosensitive drum 1 actually used for toner development is set to V _D, and a voltage having the same potential as V _D is applied between the transparent conductive layer 102 and the developing sleeve 3 so that Assuming that the surface potential rising in one rotation of the drum 1 is V _D1 and the voltage actually applied to the developing sleeve 3 in the first stage is V _S1 , the condition of the required number of applied voltage stages, n, is n ≧ Integer [(V _D / V _D1 ) +1].
Integer indicates a positive integer part in a real number.

On the other hand, the allowable time difference between the time when the voltage is applied to the developing sleeve 3 to start charging the surface of the photosensitive drum 1 and the time when the exposure device 2 starts the writing operation, that is, the time when the exposure is started, is t ₀ , Rotation speed of the photosensitive drum 1
Is a diameter of d, the condition of the timing at which the voltage can be applied to the developing sleeve 3 by increasing the voltage stepwise is t ₀ > nπ
d / v.

Under these conditions, by using a relay circuit as shown in FIG. 7 and activating and opening each relay at the timing shown in FIG. 8, the applied voltage is increased in accordance with the rotation of the photosensitive drum 1. Thus, the applied voltage can be increased in accordance with the increase in the surface potential of the photosensitive drum 1. Therefore, the surface of the photosensitive drum 1 and the toner 5
The surface potential of the photosensitive drum 1 can be increased while maintaining the potential difference between the photosensitive drum 1 and the photosensitive drum 1 in an extremely small range, and the photosensitive drum 1 is charged to a predetermined potential.

On the other hand, immediately before the toner 5 separates from the photosensitive drum 1 charged as described above, as shown in FIG. When exposed (L portion in the figure), the resistance value of the photoconductive layer 101 in that portion decreases, and the surface potential becomes substantially the same as the transparent conductive layer 102.

Therefore, a force acting between the photosensitive drum 1 and the developing sleep 3, such as an electric field and a Van der Waals force, acting between the photosensitive drum 1 and the developing sleep 3, overcomes the magnetic force, and As shown in FIG. 6, the toner 5 remains on the surface of the photosensitive drum 1 corresponding to the above-described exposed portion (L portion). Thus, a toner image corresponding to the optical information from the exposure device 2 is formed on the photosensitive drum 1.

As described above, the toner image formed on the surface of the photosensitive drum 1 is applied to the transfer roller 14 by applying a voltage having a polarity opposite to the charge injected into the toner image, as shown in FIG. Then, the toner image is transferred onto the surface of the transfer belt 22 at a pressure contact portion between the photosensitive drum 1 and the transfer roller 14.

On the other hand, a CPU (not shown) of an engine controller (not shown) such that the toner image on the surface of the transfer belt 22 and the transfer paper P correspond to each other at the pressure contact portion between the transfer belt 22 and the pressure roller 17 on the heating device 15. Central Processing Uni
By sending a signal to the paper feed solenoid 11 from t), the above-described rotation stop state of the registration roller 12 is released,
The transfer paper P is transported to a pressure contact portion between the transfer belt 22 and the pressure roller 17.

Then, the transfer belt 22 onto which the toner image has been transferred and the transfer paper P are heated by the heating device 15 and the pressing roller 1.
7, the toner image is transferred onto the transfer paper P and fixed at the same time. That is, when the transfer paper P is sent out in pressure contact between the transfer belt 22 and the pressure roller 17, the releasability of the toner 5 heated and melted by the heating device 15 is higher than that of the transfer paper P. Since the surface is better, most of the toner 5 on the surface of the transfer belt 22 is transferred and fixed onto the transfer paper P.

Thereafter, the transfer paper P on which the toner image has been transferred and fixed is pushed up by the paper ejection actuator 18 and is discharged from the apparatus through the transfer paper discharge opening by the rotation of the transport roller 20. After a predetermined time has passed since the transfer paper P was discharged out of the apparatus, the power supply to the heating resistor 16 of the heating device 15 and the driving of the main motor 23 were stopped, and a series of operations as described above was performed. Ends.

As described above, in the electrophotographic apparatus of this embodiment, the developing sleep 3 and the transparent conductive layer 10 of the photosensitive drum 1 are used.
The toner 5 held in the developing sleep 3 is slid on the photosensitive drum 1 while applying a voltage in a stepwise manner in accordance with an increase in the surface potential of the photosensitive drum 1 between the photosensitive drum 1 and the voltage. Thus, the surface potential of the photosensitive drum 1 and the developing sleeve 3
Is charged until the surface potential of the photosensitive drum 1 reaches a predetermined value while maintaining the potential difference within a small range, and then exposure is performed from the inside of the photosensitive drum 1 to expose a toner image corresponding to an image pattern. It is formed on the surface of the body drum 1.

Conventionally, the voltage applied between the photosensitive drum and the developing sleeve as described above is substantially the same as a predetermined surface potential of the photosensitive drum. A potential difference is generated between the potential and the potential, so that the charged toner may adhere to the surface of the photosensitive drum due to the potential difference. As a result, conventionally, the toner adhered to the surface of the photosensitive drum is transferred from the transfer belt onto the transfer material, the fog density of the transfer material is increased, and the image transferred on the transfer material is also unclear.

However, in the structure of the above embodiment, the transparent conductive layer 1
Since the voltage applied between the photosensitive drum 1 and the developing sleeve 3 is increased, the potential difference between the surface potential of the photosensitive drum 1 and the toner 5 can be made almost zero. Adhesion to the photosensitive drum 1 can be prevented. Thereby, the fog density on the transfer paper P can also be reduced, and a clear image can be obtained.

Further, since there is no need to provide a charger such as a corona discharger for charging the surface of the photosensitive drum 1, there is no risk of generating ozone in the charging step.
Since the exposure device 2 is disposed in the photoconductor drum 1, a dedicated space for disposing the exposure device 2 is not separately required, and the entire device can be configured to be extremely small. 2 is covered with the photoconductive drum 1, so that the adhesion of dirt is reduced. As a result, it is possible to stably maintain the amount of irradiation light from the exposure device 2 for a long period of time, and thereby maintain good image quality.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, in the above embodiment, the photoconductive layer from the surface side, the transparent conductive layer is an example using the photosensitive drum provided sequentially over the transparent support, but in order to improve the charge retention characteristics, It is also possible to use a photoconductor having a configuration in which a blocking layer is provided between the photoconductive layer and the transparent conductive layer. Further, in the above-described configuration, the example in which the voltage is applied to the developing sleeve 3 in multiple stages has been described.
A band-shaped electrode may be provided at a position opposite to the electrode insulated from the developing sleeve 3, and a voltage may be applied to the electrode in multiple stages.

On the other hand, in the above-described embodiment, the toner melted on the surface of the transfer belt 22 by heating is pressed against the transfer paper P over the transfer belt 22 to thereby transfer the toner to the transfer belt 2.
2 is transferred and fixed onto the transfer paper P from above. Therefore,
Since a transfer device including a corona discharge device or the like in the conventional Carlson process is not required, the overall shape can be made smaller, and transfer and fixing are performed simultaneously. After the transfer to the material, the toner image is suppressed from being disturbed as compared with the case where the toner image is further conveyed to the fixing device and the fixing is performed, whereby a clear image can be formed.

Further, in the above embodiment, the toner 5 having conductivity and magnetism is used, but it is also possible to adopt a configuration in which development is performed using a toner other than the toner 5 used in the electrophotographic system. is there. Further, in the above embodiment, the example in which the transfer belt 22 is made of a polyimide resin has been described. However, if the transfer belt 22 can be formed into an endless belt shape with an insulating film having appropriate mechanical strength. ,
For example, it can be made of another material such as a polyamide resin.

[0062]

As described above, according to the electrophotographic apparatus of the present invention, the voltage is applied between the toner holding member for holding the conductive magnetic toner by magnetic force and the transparent conductive layer of the photosensitive member. The surface of the photoconductor is charged with toner while being slid, the photoconductor layer of the photoconductor is exposed, a toner image is formed on the surface of the photoconductor, and the toner image is transferred to a transfer material.
In the electrophotographic apparatus for fixing, the magnetic toner
When sliding the surface of the optical body, these toner holders
This is a configuration including a control means for increasing the voltage applied between the transparent conductive layer and the transparent conductive layer in multiple stages.

Therefore, in the above-described configuration, when charging is applied between the toner holding member and the transparent conductive layer, control means for increasing the applied voltage to the predetermined voltage in multiple steps is provided. As a result, the initially applied voltage can be set lower than in the prior art, so that the potential difference between the magnetic toner and the surface of the photoreceptor is reduced.

Therefore, the attraction between the magnetic toner and the surface of the photoreceptor due to such a potential difference can be reduced, while the magnetic force between the magnet of the toner holder and the magnetic toner is maintained. It is possible to reduce the unexpected amount of toner attached to the surface of the photoconductor corresponding to the non-image portion that has not been processed.

As a result, the above configuration can reduce the stain on the non-image portion of the photosensitive member, so that the fog density on the transfer material can be reduced, and the image obtained on the transfer material can be sharpened. To play.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus of the present invention.

FIG. 2 is an explanatory diagram illustrating development in the electrophotographic apparatus.

FIG. 3 is a main part configuration diagram showing a modification of the electrophotographic apparatus.

FIG. 4 is an explanatory diagram showing a state in which the surface of a photosensitive drum in the electrophotographic apparatus is charged by contact with toner.

FIG. 5 is an explanatory diagram showing a state in which the surface of the photosensitive drum is neutralized by exposure of an exposure device.

FIG. 6 is an explanatory diagram showing a state where a toner image is formed on the surface of the photosensitive drum.

FIG. 7 is a circuit diagram showing one method of controlling an applied voltage in the electrophotographic apparatus.

FIG. 8 is a timing chart of the above circuit diagram.

FIG. 9 is a graph illustrating a rise in surface potential of the photosensitive drum.

FIG. 10 is a schematic diagram of a main part of an electrophotographic apparatus for explaining the above-described rise in surface potential and an equivalent circuit diagram of the schematic diagram of the main part.

FIG. 11 is a schematic configuration diagram showing an electrophotographic apparatus employing a conventional Carlson process.

FIG. 12 is a schematic cross-sectional view illustrating a developing method of an electrophotographic apparatus employing a conventional image forming process using a conductive magnetic toner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum (photoconductor) 2 Exposure apparatus (exposure means) 3 Developing sleeve (toner holder) 4 Magnetic roller (magnet) 5 Toner (magnetic toner) 25 Control means 101 Photoconductive layer 102 Transparent conductive layer 103 Transparent support P Transfer paper (transfer material)

Claims (1)

(57) [Claims] 1. A photoconductor in which a photoconductor layer, a transparent conductive layer, and a transparent support are sequentially stacked from the surface side, and a magnet are built in,
The magnetic toner having a conductivity and a exposing means for exposing the upper Kikoshirube collector layer above the photosensitive member and the toner carrier to be supplied to the surface of, through the upper Symbol transparent support and the transparent conductive layer, the toner Do not apply voltage between the holder and the transparent conductive layer.
The magnetic toner is brought into sliding contact with the surface of the photoreceptor.
The surface of this photoreceptor has the same polarity as the magnetic toner
And a portion in sliding contact with the magnetic toner on the photoreceptor
This position is exposed by the above-mentioned exposure means,
In an electrophotographic apparatus in which a visible image of a magnetic toner is formed on the surface of a photoreceptor and the visible image of the magnetic toner is transferred and fixed to a transfer material, when the magnetic toner is brought into sliding contact with the surface of the photoreceptor, This
Electrophotographic apparatus characterized in that it comprises a voltage applied between the these toner holder and the transparent conductive layer, a control means for raising the multi-stage.