JP3246713B2 - 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 developing and recovering untransferred toner on a photosensitive member by a developing device.

[0002]

2. Description of the Related Art Conventionally, this type of electrophotographic apparatus has the following structure. That is, a photoreceptor made of a rotatable negatively charged organic material, a charging device for charging the surface of the photoreceptor, and a surface of the photoreceptor positioned downstream of the photoreceptor in the rotational direction of the photoreceptor with respect to the charging device. And an exposure device for forming an electrostatic latent image.

Further, a two-component developer, which is located on the downstream side in the rotation direction of the photoreceptor with respect to the exposure device and is carried on a developing roller, adheres to the surface of the photoreceptor to develop an electrostatic latent image to form a toner image. A two-component developing type developing device, a non-contact type transferring device located downstream of the developing device in the rotation direction of the photoreceptor and transferring a toner image of the photoreceptor to recording paper, and the transferring device And a stationary disturbing device which is located downstream of the photosensitive member in the rotation direction of the photosensitive member and which contacts a fixed blade to the surface of the photosensitive member to disturb the toner remaining on the surface of the photosensitive member after transfer.

In the electrophotographic apparatus having this configuration, the photosensitive member is rotated at the time of image recording, the photosensitive member is charged by the charging device with the rotation, and an electrostatic latent image is formed on the photosensitive member by the exposure device. Then. In the developing device, toner is adhered to the photoreceptor to form an electrostatic latent image to form a toner image.

Next, the toner image on the photoreceptor is transferred to a recording paper by a transfer device. In this transfer device, all of the toner adhering to the photoreceptor is not transferred to the recording paper, and part of the toner remains on the photoreceptor (transfer residual toner). Next, the transfer residual toner remaining on the photoreceptor is disturbed by a fixed disturber, and then the transfer residual toner is recharged by a charging device, and thereafter the transfer residual toner is absorbed and collected by a developing roller in a developing device. That is, the developing device performs both the development operation and the transfer residual toner collection operation.

However, in the two-component developing system employed in the conventional electrophotographic apparatus, it is necessary to provide a mechanism for controlling the density of the toner, so that the developing apparatus tends to be larger and heavier. In addition, there is a restriction on the setting of the voltage applied to the charging device and the developing roller. If the potential difference is too large, the carrier in the developer has a polarity opposite to that of the toner, causing a problem that the photoconductor is deteriorated and the image quality is deteriorated. .

In order to solve such a problem, an electrophotographic apparatus using a non-contact one-component developing type developing device has been proposed. This recording apparatus can avoid the problem in the two-component developing method, but it is necessary to apply an AC voltage of DC superimposition to the developing roller because the potential difference between the photosensitive member and the developing roller must be increased. There is a problem that equipment for a high-voltage power supply to be used becomes expensive.

Further, in the non-contact one-component developing type developing device used in the electrophotographic apparatus, it is necessary to keep the charge amount of the toner low in order to cause the toner to fly between the developing roller and the photosensitive member by an AC electric field. . Further, in this recording apparatus, when the transfer residual toner on the photoreceptor is recharged by the charging device and then collected by the developing roller, there is a problem that the toner is excessively charged by the charging device and the toner cannot be collected by the developing roller. I have.

[0009]

In order to solve such a problem, an electrophotographic apparatus using a developing device employing a non-magnetic one-component contact developing system has been proposed. In this developing method, a developing electrode is present in close proximity to the electrostatic latent image formed on the photosensitive drum via the toner, so that development faithful to the electrostatic latent image can be performed. For this reason, if the transfer residual toner on the photoconductor is above the charged potential (white potential), the transfer residual toner is smoothly collected by the developing roller.

However, in this electrophotographic apparatus, paper dust generated by the conveyance of the recording paper adheres to the photosensitive member. And
The fixed toner disturbing member adsorbs the paper dust but cannot hold it, so it is immediately discharged onto the photoreceptor.
This paper dust enters between the developing roller and the toner charging device,
This hinders the charging of the toner and causes image deterioration. Further, when the paper dust adhered to the photoreceptor collects the toner in the developing device, the paper dust enters the inside of the developing device together with the toner and deteriorates the image.

Further, since a negatively charged organic photoreceptor is used, the toner is used after being negatively charged. The above-mentioned paper powder contains an inorganic filler (talc, calcium carbonate, etc.) in the paper. In particular, talc has good triboelectricity,
It has the property of charging itself negatively and charging the other side positively, and if it enters the developing device, it charges the toner, which should be negative, positively, causing image deterioration such as image fogging.

Further, in the case of a non-contact type transfer device such as a corotron, a conventional transfer device uses a non-contact type transfer device, the transfer efficiency of the toner fluctuates depending on the surrounding environment, and the transfer remaining toner is reduced. The amount also varies. For this reason, there arises a problem that the voltage of the toner disturbance device on the downstream side with respect to the developing device cannot be set. In order to improve this, there is a method of stabilizing the discharge by using a scorotron transfer device. However, the method is expensive and the grid surface is stained by toner.

There is also a method in which a voltage having a polarity opposite to that of the toner (a voltage equal to or higher than the discharge start voltage of the brush) is constantly applied to the disturbance member, and the toner is sucked and discharged by charge injection.
Since there is a time difference from the suction to the discharge by the charge injection, the amount of toner held by the brush increases as the number of recording sheets increases.

Therefore, the amount of toner discharged from the brush to the photosensitive member also increases, so that it is difficult to collect all of the toner by the developing roller, and the remaining toner on the photosensitive member appears as an image in the positive memory. Problems arise.

The present invention has been made in view of the above circumstances, and realizes simultaneous development cleaning using a positively charged organic photoreceptor, non-magnetic one-component contact development, and a conductive brush roller.
Reduces the size, weight, and cost of the device, prevents deterioration of the photoconductor, prolongs its life, and enables good image formation.Especially, the operation of the conductive brush roller enhances the effect of simultaneous development and cleaning. It is an object to provide an electrophotographic apparatus.

[0016]

According to the first aspect of the present invention, there is provided an electrophotographic apparatus comprising: a photosensitive member made of a positively charged organic material and rotated during image recording; a charging device for charging the photosensitive member; An exposure device that is located downstream of the photoconductor rotation direction and that exposes the photoconductor to form an electrostatic latent image; and an exposure device that is located downstream of the photoconductor rotation direction and is in rotational contact with the photoconductor. A developing roller that carries a non-magnetic one-component developer on a developing roller and adheres to the photoconductor to visualize the electrostatic latent image to form a toner image; and a downstream side in the photoconductor rotating direction with respect to the developing device. A contact-type transfer device that transfers the toner image of the photoconductor onto recording paper by a roller that is in contact with the photoconductor, and is located downstream of the photoconductor in the photoconductor rotation direction with respect to the transfer device and is in contact with the photoconductor. After the transfer by the transfer device, the photosensitive Aspirated transfer residual toner remaining on,
A rotatable conductive brush roller for discharging, and applying a voltage having a lower potential than the potential of the photoconductor to the conductive brush roller when the image recording area of the photoconductor passes through the conductive brush roller. And when a non-image recording area on the photoconductor passes through the conductive brush roller, applies a voltage higher than the potential of the photoconductor to the conductive brush roller, and furthermore, the conductive brush roller is The photosensitive drum rotates in the opposite direction, and the peripheral speed of the conductive brush roller at the contact position between the conductive brush roller and the photosensitive member is equal to or faster than the peripheral speed of the photosensitive member. And

According to the structure of the present invention, the following operation is obtained.

This electrophotographic apparatus comprises a positively charged organic photoreceptor, a non-magnetic one-component contact developing device, a contact transfer device, a rotating conductive brush roller, and a bias voltage applied to the conductive brush roller. Simultaneous development and cleaning is performed by using a device that switches between a recording area and a non-recording area.

First, at the time of image recording, a voltage lower than the surface potential of the photoconductor in contact with the conductive brush roller is applied to the conductive brush roller to remove the transfer residual toner in the recording area of the photoconductor. Then, the toner is temporarily sucked into the conductive brush roller by the potential difference between the photosensitive member and the conductive brush roller.

At the time of passing through the non-recording area, by applying a voltage higher than the surface potential of the photosensitive member in contact with the conductive brush roller, the toner taken into the conductive brush roller is discharged to the photosensitive member side. return. The toner returned to the photoconductor is recharged by the photoconductor charging device and collected by the developing roller.

As described above, the toner is removed from the photoconductor by the conductive brush roller in the recording area of the photoconductor, and the removed toner is returned to the photoconductor in the non-recording area (before and after recording, between pages). to recover. During recording, the surface of the photoreceptor is the same as the cleaned state, so that no positive / negative memory is generated.

Since the toner returned from the conductive brush roller is immediately collected by the developing roller before and after recording, a large amount of toner is not accumulated on the conductive brush roller. Since the amount of toner accumulated on the conductive brush roller is small, the amount of toner returned to the surface of the photoreceptor is small, and collection failure by the developing roller does not occur. It can be removed from the photoreceptor by the driving force of the brush roller. further,
Even if some of the paper dust is mixed into the developing device, it does not hinder the charging of the toner because the toner has a positive polarity.

The conductive brush roller rotates in the opposite direction to the photosensitive member and slides on the surface of the photosensitive member at the same or faster peripheral speed as the photosensitive member. The operation of sliding on the surface of the photoconductor and scraping off the toner on the surface of the photoconductor is further enhanced.

Therefore, when the conductive brush roller sucks the toner from the photosensitive member, the conductive brush roller can more reliably scrape the toner in the image area on the photosensitive member. As a result, the conductive brush roller can scrape more toner from the photoreceptor surface, and the toner suction ability is improved.

Further, when the peripheral speed of the conductive brush roller is higher than the peripheral speed of the photosensitive member, the conductive brush roller discharges toner to a non-image area of the photosensitive member when the conductive brush roller discharges toner to a non-image area. The distance that the surface contacts the surface (peripheral surface) of the photoreceptor can be increased. For this reason, a large amount of the toner held by the conductive brush roller can be discharged, and the discharge of the toner is advantageous.

Therefore, according to the present invention, the conductive brush roller has an excellent toner absorbing ability, and the effect of cleaning at the same time as the development is enhanced, so that good image recording can be performed.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. A schematic configuration of an image recording process in an electrophotographic apparatus will be described with reference to FIG. This electrophotographic apparatus employs a reversal development and cleanerless system.

The photoreceptor 1 is in the form of a drum made of a positively charged organic material, and is rotated in a direction indicated by an arrow by a rotation driving device (not shown). The scorotron-type charging device 2 charges the surface of the photoconductor 1, and the exposure device 3 is located downstream of the charging device 2 in the rotation direction of the photoconductor 1 and is based on image data. Is exposed to form an electrostatic latent image.

The non-magnetic one-component contact developing device 4 is provided downstream of the exposure device 3 in the rotation direction of the photosensitive member 1. The developing device 4 includes a toner hopper 5 for storing a toner T which is a non-magnetic one component, and a developing roller 6 which carries the toner T and contacts the surface (outer peripheral surface) of the photoconductor 1.
have.

A supply roller 7 for supplying the toner T stored in the toner hopper 5 to the developing roller 5;
And a developing blade 8 for thinning the toner T carried by the toner and frictionally charging the toner T. Developing roller 6
The supply roller 7 is rotated in a direction indicated by an arrow by a rotation driving device (not shown). The stirrer 9 stirs the toner T.

The transfer roller 10 is an example of a member that comes into contact with the surface of the photoreceptor 1 in a contact type transfer device, and is located downstream of the photoreceptor 1 with respect to the developing device 4 in the rotation direction. It is provided in contact with the surface (outer peripheral surface). The transfer roller 10 is rotated in a direction indicated by an arrow by a rotation driving device (not shown).

The conductive brush roller 11 is a transfer roller 10
Is provided on the downstream side in the rotation direction of the photoconductor 1 and on the upstream side in the rotation direction with respect to the charging device 2.

The conductive brush roller 11 is formed by implanting a large number of bristles 13 made of a conductive material around a shaft 12 and has a resistance of about 10 ⁶ Ω. The conductive brush roller 11 is disposed in parallel with the photoreceptor 1, the shaft 12 is rotatably supported on a frame (not shown) equipped with an electrophotographic apparatus, and the tip of the bristles 13 is brought into contact with the surface of the photoreceptor 1. ing. The shaft 12 of the conductive brush roller 11 is rotated in a direction indicated by an arrow by a rotation driving device (not shown).

The static eliminator 14 is provided between the transfer roller 10 and the conductive brush roller 11, and reduces the potential of the surface of the photoconductor 1.

Incidentally, the recording paper cassette 31 is for accommodating the recording paper P in a stacked manner, and the pickup roller 32 is for feeding out the recording paper P from the recording paper cassette 31. Between the recording paper cassette 31 and the photoreceptor 1, a transport roller 33, a recording paper sensor 34,
A registration roller 35 is provided. A heat fixing roller 36 is provided downstream of the photoconductor 1 in the recording paper conveyance direction, and a discharge roller 37 is provided further downstream. These rollers are rotated by a rotary drive device in the recording paper transport direction.

The power supply 21 supplies + (plus) 20 to the charging device 2.
A current of 0 μA is supplied, and the Zener diode 22 regulates this charged potential.
Is for applying a bias voltage of +300 V to the developing roller 6 of the developing device 4. The power supply 24 supplies +
A bias voltage of 400 V is applied.
Reference numeral 5 denotes a bias voltage of-(minus) 1000 V applied to the transfer roller 10.

The power supply 26 applies a bias voltage to the conductive brush roller 11. This means that a bias voltage of +300 V is applied when the non-recording area of the photoconductor 1 passes through the conductive brush roller 11 by switching the switch 27, and 0 V when the recording area of the photoconductor 1 passes through the conductive brush roller 11. Is applied.

The operation of the image recording process in the electrophotographic apparatus according to this embodiment will be described with reference to FIG.
At the time of image recording, the following operation is performed while the photoconductor 1 is being rotated. In image recording, a negative latent image is formed and reversal development is performed. The photoconductor 1 is positively charged, and the toner T is also positively charged.

The photoreceptor 1 is rotated in the direction of the arrow by a rotary driving device. While the photoconductor 1 rotates, an image is formed by the process described below.

First, the surface of the photosensitive member 1 which is positively charged is charged to +600 V by the scorotron charging device 2, and then the surface of the photosensitive member 1 is exposed by the exposure device 3 in accordance with image data to form an electrostatic latent image. I do. In this case, a black image has a potential of +150 V, and a white image has a potential of +600 V.

In the developing device 4, a bias voltage of +300 V is applied to the developing roller 6 by the power source 23, a bias voltage of +400 V is applied to the supply roller 7 by the power source 24, and the rollers 23 and 24 are rotated. The rotation of the supply roller 24 supplies the toner T stored in the toner hopper 5 to the developing roller 6.

The developing roller 6 rotates in contact with the surface of the photoreceptor 1, and carries the toner T to apply it to the surface of the photoreceptor 1. In this case, the blade 8 forms a thin toner layer. In this way, the positively charged toner T adheres to the surface of the photoconductor 1 according to the electrostatic latent image to form a toner image on the surface of the photoconductor 1.

Here, the recording paper P stacked on the recording paper cassette 31 is sequentially sent out by the rotation of the pickup roller 32, and the sent out recording paper P is transported by the transport roller 33 to the registration roller 35. The registration roller 35 stops rotating, receives the recording paper P, controls the attitude of the recording paper P, and then rotates in synchronization with the rotation of the developing roller 6 to rotate with the photosensitive member 1 that contacts the recording paper P with each other. The sheet is conveyed to and from the transfer roller 10.

The transfer roller 10 has a power supply 25
A bias voltage of 00V is applied to transfer the toner image on the surface of the photoconductor 1 to the recording paper 1. Note that not all the toner T of the photoconductor 1 is transferred to the recording paper P in the transfer process, and 10 to 20% of the toner remains on the surface of the photoconductor 1.

Next, the potential on the surface of the photosensitive member 1 is reduced by the charge removing device 14.

Thereafter, the conductive brush roller 11 which comes into contact with the surface of the photoreceptor 1 is rotated by a rotation driving device. At this time, when the image recording area on the photoconductor 1 passes through the conductive brush roller 11, a voltage having a potential lower than the potential of the photoconductor 1 is applied to the conductive brush roller 11, and the electroconductive brush roller 11 remains on the photoconductor 1. The toner T is sucked and held by the conductive brush roller 11.

When a non-image recording area on the photosensitive member 1 passes through the conductive brush roller 11, a voltage higher than the potential of the photosensitive member 1 is applied to the conductive brush roller 11, so that the conductive brush roller 11 The suctioned and held toner T is discharged onto the surface of the photoconductor 1.

Further, the rotation of the conductive brush roller 11 is controlled so that the conductive brush roller 11 and the photosensitive member 1 are in sliding contact, that is, in sliding contact with each other, and the conductive brush roller 11 removes the residual toner T of the photosensitive member 1. When sucking, a mechanical force is applied together with an electric force. As a result, the residual toner T adhering to the surface of the photoreceptor 1 is reliably scraped off and sucked effectively.

Then, the discharged toner T is charged into the charging device 2.
To increase the potential. Next, the developing device 4
Then, the toner T is sucked by the developing roller 6 biased to 300 V and collected in the toner box 4 of the developing device 4.

Next, the process of collecting the toner remaining on the photoreceptor 1 after the transfer to the developing roller 5 will be described with reference to FIGS.

FIG. 2 is a chart showing the control timing of the process. The timing of bias application in the photosensitive member (drum), the developing roller 6, the exposure device 3, the charging device 2, the transfer roller 10 and the conductive brush roller 11 is shown. Is shown. This chart includes the conductive brush roller 11
Indicates that the control is performed by switching the bias for the recording area (applied bias of 0 V) and the non-recording area (applied bias of +30 V).

FIG. 3 is a diagram showing the surface potentials near the developing device 4 and the conductive brush roller 11 when black is printed by the process control shown in FIG. As shown in the surface potential waveform of FIG. 3, in the recording area, the toner T and the paper dust S are at about 70 V as the photoconductor potential after passing through the transfer roller 10. Note that the photoconductor potential attenuated from 150 V to 70 V because the transfer roller 5 was charged to the negative side.

Here, a voltage of 0 V, which is lower than the potential of the photosensitive member 1, is applied to the conductive brush roller 11 by the power supply 16. Therefore, + (plus) on the surface of the photoconductor 1
The toner T is applied to the surface of the photoconductor 1 by the conductive brush roller 11.
When the conductive brush roller 11 comes into contact with the conductive brush roller 11, it is attracted to the conductive brush roller 11 by the potential difference between the photosensitive member 1 and the conductive brush roller 11. Further, the − (minus) toner T on the surface of the photoconductor 1 passes through the conductive brush roller 11 as it is.

FIG. 4 shows that the transfer residual toner T existing in the recording area of the photosensitive member 1
FIG. 7 is a diagram showing a change when the image forming apparatus moves from the developing device to the developing device. That is, the graph shows the change of the transfer residual toner at each time point after passing through the transfer roller, at the time of contact with the conductive brush roller, after passing through the conductive brush roller, after passing through the charging device, and at the time of contact with the developing roller. In FIG. 4, + and-circled indicate + toner and-toner.

As shown in FIG. 4, the conductive brush roller 11
Is left as it is, the polarity of the transfer residual toner T is inverted to + by the charging device 2, and is raised to a potential of + 600V. Then, in the developing device 4, 3
The toner is sucked by the developing roller 6 biased to 00V and collected into the toner hopper 5 of the developing device 4. At this time,
Since toner hardly exists on the surface of the photoconductor 1,
This toner does not interfere with the photosensitive device, and no positive / negative memory is generated. Most of the untransferred toner T is + toner.

The white potential portion in the recording area of the photosensitive member 1 attenuates to 200 V when passing through the conductive brush roller 11. This is because the photoconductor 1 has a transfer roller 8
Is charged to one side. Since 0 V is applied to the conductive brush roller 11 by the power supply 25, the toner accumulated in the conductive brush roller 11 does not return to the white potential portion of the photoconductor 1.

Next, a description will be given of a process in which the + toner sucked by the conductive brush roller 11 in the recording area of the photosensitive member 1 is collected by the developing roller 6 in the non-recording area.

First, as shown in the timing chart of FIG.
To apply a bias voltage of +300 V to the conductive brush roller 11. As shown in the surface potential waveform shown in FIG. 3, the photosensitive member 1 is electrically conductive brush roller 11 before recording.
Is on one side, between pages (emergency recording area) and around 0 V after recording.

Therefore, a conductive voltage (300 V) higher than the above potential is applied to the conductive brush roller 11. FIG. 5 shows that the toner T of the photoconductor 1 in the non-recording area at this time is
FIG. 6 is a diagram showing a change when the transfer roller moves from the transfer roller 10 to the developing device 4 with the rotation of FIG. That is, the graph shows changes in the untransferred toner T at each time point after passing through the transfer roller, at the time of contact with the conductive brush roller, after passing through the conductive brush roller, after passing through the charging device, and at the time of contact with the developing roller. FIG.
In the figure, + surrounded by a circle indicates + toner T.

As shown in FIG. 5, the surface of the photoconductor 1 after passing through the transfer roller 5 of the photoconductor drum 1 is in a state without toner. This is because the potential at the time of exposure is a white potential in the non-recording area of the photoconductor 1,
This is because there is no toner development due to the above.

When the photosensitive member 1 passes through the conductive brush roller 11, the + toner in the recording area sucked by the conductive brush roller 11 is removed by the potential difference between the conductive brush roller 11 and the photosensitive member 1. Return to the surface of 1. The returned + toner T is recharged by the charging device 2 to have a potential of +60.
Pull up to 0V. Next, in the developing device 4, 30
The toner T is sucked by the developing roller 6 biased to 0 V and collected by the developing device 4.

Here, the present invention was carried out, and an intermittent sheet passing test was performed on 18.5K sheets (recording of a black ratio of 5%). In this test, the total toner consumption was 504 g and the amount of toner accumulated in the conductive brush roller 8 was 2 g, and no negative or positive memory was generated. Assuming that the transfer efficiency in the transfer step is 80%, about 100 g of the transfer residual toner is generated, and about 98% of the transfer residual toner is collected by the developing device. From this, it can be said that development and cleaning are simultaneously and smoothly performed in the developing device 4 according to the present invention.

On the other hand, in the transfer step, the paper dust S of the recording paper P adheres to the surface of the photoreceptor 1. Then, the surface of the photoconductor 1 reaches the conductive brush roller 11. The conductive brush roller 11 is forcibly rotated by the rotation driving device, and the bristles 13 slide on the surface of the photoconductor 1. For this reason, the bristles 13 of the conductive brush roller 11 remove and hold the paper dust S attached to the surface of the photoconductor 1.

Thus, the paper dust S adhered to the surface of the photoreceptor 1 in the transfer step is removed by the conductive brush roller 11. Since the paper dust S is not as closely adhered to the photoconductor as the toner T, the paper powder S can be removed from the photoconductor 1 by the driving force of the conductive brush roller 11. Even if some of the paper dust S is mixed into the developing device 4 by the developing roller 6, the toner T does not hinder the charging of the toner T because the toner T has a positive polarity. Therefore, it is possible to avoid various problems caused by the presence of the paper dust S.

Next, the rotation of the conductive brush roller 11 is controlled to bring the conductive brush roller 11 and the photosensitive member 1 into sliding contact, that is, sliding contact, so that the conductive brush roller 11 The point that the residual toner T is sucked by applying a mechanical force together with an electric force when sucking the toner will be described.

In order to bring the conductive brush roller 11 and the photosensitive member 1 into sliding contact with each other, the conductive brush roller 11 and the photosensitive member 1 are rotated in opposite directions to each other, and the conductive brush roller 11 and the photosensitive member 1 are rotated. At the contact portion, the peripheral speed of the conductive brush roller 11 may be equal to or higher than the peripheral speed of the photoconductor 1. Alternatively, the conductive brush roller 11 and the photoreceptor 1 may be rotated in the same direction at different rotational speeds so as to have a relative peripheral speed difference between the contact portions of the two.

Hereinafter, this point will be described with reference to the diagram shown in FIG. The diagram shown in FIG. 6 shows that the amount of toner remaining on the photosensitive member after passing through the conductive roller member / the amount of toner remaining on the photosensitive member after the transfer when the rotation conditions of the four types of conductive roller members were changed. Amount). In the diagram shown in FIG. 6, the horizontal axis represents the peripheral speed ratio (speed ratio) of the conductive roller member to the peripheral speed of the photoconductor 1,
The vertical axis indicates the amount of toner remaining on the photoconductor after passing through the conductive roller member / the amount of toner remaining on the photoconductor after transfer.

The horizontal axis is represented by the equation of (VK-VC) / VC.

[0069] (However, when the rotation direction of the conductive roller member and the rotation direction of the photoconductor 1 are opposite at the contact position with the photoconductor 1, the value is negative.) The numerical values on the horizontal axis indicate the following conditions. The horizontal axis “0” indicates a case where the conductive roller member has the same peripheral direction and the same rotational speed as the photoconductor 1. The horizontal axis "-1" indicates the case where the conductive roller member has stopped rotating. Horizontal axis `` −
"2" is a case where the conductive roller member has the same peripheral speed as the photosensitive member 1 in the opposite rotation direction.

The vertical axis indicates the residual toner on the surface of the photosensitive member 1 after passing through the transfer roller 10 when the “solid black” recording is performed, and the photosensitive member 1 after passing through the conductive roller member.
This is the ratio of the values obtained by manually measuring the toner remaining on the surface with a mending tape and measuring with a colorimeter.

At this time, the conductive roller member is in the toner suction mode (a voltage having a polarity opposite to that of the toner T is applied). That is, the smaller the numerical value on the vertical axis, the more the conductive roller member sucks the residual toner after the transfer.

The conductive roller members to be evaluated include (a): a rotating brush roller (initial), (b): a rotating brush roller of (a) (after running 12K), and (c): a sponge roller A ( (Initial), (d): four types of sponge roller B (initial).

The following can be said from the diagram of FIG.

At the contact position between the conductive roller member and the photosensitive member 1, if the conductive roller member is rotating at the same speed in the same rotational direction as the photosensitive member 1, the toner absorption rate is the worst. When the peripheral speed ratio of the conductive roller member to the photoconductor 1 is increased regardless of the rotation direction of the conductive roller member, the toner absorption rate is improved.

However, when the conductive roller member is rotating in the same rotation direction as the photosensitive member 1 at the contact position between the conductive roller member and the photosensitive member 1, the conductive roller member moves in the direction of the charging device 2. In some cases, the toner T and the paper dust S are scattered and adhere to a wire provided in the charging device 2 to cause poor charging. For this reason, it is preferable to rotate the conductive roller member in a direction opposite to the rotation direction of the photoconductor 1.

When the direction of rotation of the conductive roller member is opposite to the direction of rotation of the photosensitive member 1, the toner absorptivity is better than when the direction is the same. Further, when the rotation direction of the conductive roller member is opposite to the rotation direction of the photoconductor 1, if the peripheral speed of the conductive roller member is equal to or higher than the peripheral speed of the photoconductor 1, it is high. Saturates at the toner absorption rate. Therefore, the toner on the surface of the photoconductor 1 can be more effectively peeled off from the conductive brush roller 11.

As described above, since the conductive brush roller 11 and the photosensitive member 1 are in sliding contact with each other, the conductive brush roller 11 comes into sliding contact with the conductive brush roller 11 at the contact position.

For this reason, when the conductive brush roller 11 sucks toner from the image area of the photoconductor 1, the conductive brush roller 11 contacts the surface of the photoconductor 1 at the contact position between the photoconductor 1 and the conductive brush roller 11. A large mechanical force for scraping certain toner can be obtained. Accordingly, the conductive brush roller 11 can scrape off a large amount of toner from the surface of the photoreceptor 1 and has excellent toner suction ability.

Thus, the conductive brush roller 11 can sufficiently peel and remove the toner remaining in the image area on the surface of the photosensitive member 1 by a sufficient mechanical peeling force in addition to the electric peeling force.

For this reason, it is possible to prevent the toner T from remaining on the surface of the photoreceptor 1 after passing through the conductive brush roller 11 and generating noise on a recorded image during the next image recording. it can.

In particular, as described above, the conductive brush roller 1
1 is rotated in the opposite direction to the photosensitive member 1, and the peripheral speed of the conductive brush roller 11 at the contact position between the conductive brush roller 11 and the photosensitive member 1 is equal to or faster than the peripheral speed of the photosensitive member 1. Thereby, the operation of the conductive brush roller 11 sliding on the surface of the photoconductor 1 and scraping the toner T on the surface of the photoconductor 1 is further enhanced.

For this reason, when the conductive brush roller 11 sucks the toner T from the photoconductor 1, the conductive brush roller 11 is more reliably brought into contact with the photoconductor 1 at the contact position between the photoconductor 1 and the conductive brush roller 11. The toner in the image area can be scraped. Therefore, the conductive brush roller 11 can scrape more toner from the surface of the photoconductor 1, and the toner suction ability is improved.

Note that even at the time of discharging, the conductive brush roller 11 and the photosensitive member 1 are in sliding contact with each other, so that the discharging operation can be performed well.

When the peripheral speed of the conductive brush roller 11 is higher than the peripheral speed of the photosensitive member 1, the conductive brush roller 11 discharges toner to a non-image area of the photosensitive member 1 when the conductive brush roller 11 discharges toner to a non-image area. The distance in which the peripheral surface of the brush roller 11 contacts the surface (peripheral surface) of the photoconductor 1 can be increased.
Therefore, a large amount of toner held by the conductive brush roller 11 can be discharged, and discharging of the toner T is advantageous.

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications.

[0086]

As described above, according to the electrophotographic apparatus of the first aspect of the present invention, when the peripheral speed of the conductive brush roller is higher than the peripheral speed of the photosensitive member, the conductive brush roller is not used. When the toner is discharged to the non-image area on the photoconductor, the distance that the peripheral surface of the conductive brush roller contacts the surface of the photoconductor can be increased. For this reason, a large amount of the toner held by the conductive brush roller can be discharged, and the discharge of the toner is advantageous. Therefore, according to the present invention, the conductive brush roller has an excellent toner suction ability, so that cleaning at the same time as the development can be effectively realized, and good image recording can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a processing unit of an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart showing process control of the embodiment.

FIG. 3 is a diagram showing surface potential waveforms of a developing device and a conductive brush roller when black is printed in the embodiment.

FIG. 4 is a diagram showing a change in transfer residual toner in a recording area of a photoconductor in the embodiment.

FIG. 5 is a diagram showing a change in toner in a non-recording area of the photoconductor in the embodiment.

FIG. 6 is a diagram showing the results of a toner suction test on a conductive brush roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Positively charged organic photoreceptor, 2 ... Charging device, 3 ... Exposure device, 4 ... Developing device, 6 ... Developing roller, 7 ... Supply roller, 10 ... Transfer roller, 11 ... Conductive brush roller, 12 ... Shaft, 13 ... hair, 14 ... static eliminator, 21 ... power supply, 22 ... power supply, 23 ... power supply, 24 ... power supply, 25 ... power supply. 26: power supply, 31: cassette, 35: registration roller, P: recording paper, T: toner, S: paper dust.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hisayoshi Saegusa 6-78 Minamimachi, Mishima-shi, Shizuoka Pref. Inside the Technical Research Institute, Inc. (72) Inventor Osamu Tsuchiya 6-78 Minamimachi, Mishima-shi, Shizuoka Pref. (56) References JP-A-7-84467 (JP, A) JP-A 8-6454 (JP, A) JP-A 8-95453 (JP, A) JP-A 4-204787 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 21/10-21/12 G03G 21/00

Claims (1)

(57) [Claims] 1. A photoconductor made of a positively charged organic material and rotated during image recording; a charging device for charging the photoconductor; and a photoconductor positioned downstream of the photoconductor in the photoconductor rotation direction with respect to the charging device. An exposure device that forms an electrostatic latent image by exposing, and a non-magnetic one-component developer carried by a developing roller that is positioned downstream of the exposure device in the rotation direction of the photoconductor and is in rotational contact with the photoconductor. A developing device that adheres to the photoreceptor to visualize the electrostatic latent image to form a toner image; and a roller that is located downstream of the photoreceptor in the photoreceptor rotation direction and is in contact with the photoreceptor. A contact-type transfer device that transfers a toner image to recording paper; and a transfer residue that is located downstream of the transfer device in the photoconductor rotation direction and is in contact with the photoconductor and remains on the photoconductor after transfer by the transfer device. Suction and discharge toner A rotatable conductive brush roller, and when the image recording area on the photoconductor passes through the conductive brush roller, applies a voltage having a lower potential than the photoconductor to the conductive brush roller, And applying a voltage higher than the potential of the photoconductor to the conductive brush roller when the non-image recording area of the photoconductor passes through the conductive brush roller; And the peripheral speed of the conductive brush roller at the contact position between the conductive brush roller and the photoconductor is the same as or faster than the peripheral speed of the photoconductor. Electrophotographic equipment.