JP2001265187A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device equipped with a cleaning unit, whose cost is low, whose cleaning performance is high and which has a compact and simple structure. SOLUTION: A cleaning member 11 consisting of a fur brush and a bias roller or the like and a contact electrifying member 14, consisting of a metallic roller or the like of a cleaning unit 10 are disposed in one cleaning unit case 15. Thus, the members 11 and 14 are simultaneously made to contact with/ separate from an intermediate transfer belt 16, functioning as an intermediate transfer body by one contact/separation mechanism, and the structure of the intermediate transfer belt cleaning unit 10 is simplified. Then, many of the component parts of a driving system for driving the members 11 and 14 and a control system can be used in common, so that the driving torque of the contact/separation mechanism is made lower and the device becomes advantageous also in terms of the design of a control circuit than in the case the members 11 and 14 are disposed individually.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a laser beam printer, and a facsimile, and more particularly, to a method in which a toner image formed on an image carrier is transferred onto a transfer material by an electrophotographic method. A cleaning member for cleaning the transfer residual toner remaining on the image carrier after the cleaning; and a cleaning member for the cleaning unit, wherein the transfer residual toner contacts the image carrier before cleaning the transfer residual toner. And a contact charging member for charging the toner.

[0002]

2. Description of the Related Art As a color image forming apparatus for forming an image by an electrophotographic method, (1). An image forming apparatus that repeats exposure and development on a photoconductor to form a color toner image on the photoconductor, and then collectively transfers the color toner image to a transfer material such as paper to form an image. (2). Wrap a transfer material such as paper on the transfer drum,
The toner images of each color formed on the photoreceptor are transferred onto the transfer material while being superposed one by one to form a color toner image on the transfer material, and then the sheet is peeled from the transfer drum to form an image. Image forming device. (3). The toner images of each color formed on the photoreceptor are transferred (primary transfer) while being superposed one by one on the intermediate transfer body, and a color toner image is formed on the intermediate transfer body. An image forming apparatus for forming an image by batch transfer (secondary transfer) to a transfer material of the same type. Etc. are known. The image forming apparatus using the intermediate transfer member of the above (3),
There are advantages such as the ability to form images of relatively high quality and the ability to form images on a wide variety of papers.

In this type of image forming apparatus, after a toner image formed on the above-mentioned photoreceptor or an intermediate transfer member as an image carrier is transferred onto a transfer material, the transfer remaining on the image carrier is carried out. It is necessary to clean the remaining toner. As a method of cleaning the transfer residual toner, a blade method, a brush method, a roller method, and the like are generally used. The blade system is a cleaning system in which the transfer residual toner is mechanically scraped off by a cleaning member made of an elastic blade such as a rubber blade. In the brush method, a cleaning member formed of a brush roller such as a fur brush is rotated and brought into contact with the transfer residual toner, and at the same time, a bias having a polarity opposite to that of the transfer residual toner is applied to the brush roller to mechanically and electrically transfer the toner. This is a cleaning method that removes the toner. The roller system is a cleaning system in which a cleaning member including a conductive bias roller such as a metal roller to which a bias having a polarity opposite to that of the transfer residual toner is applied is brought into contact with the transfer residual toner to electrically remove the transfer residual toner. .

By the way, as a cleaning member of this type of image forming apparatus, it is advantageous to use the blade type cleaning member from the viewpoint of simplicity of construction and low cost. However, with this blade-type cleaning member, the blade tip is strongly pressed against the surface of the image carrier to scrape off the untransferred toner. The transfer residual toner remaining on the body is directly transferred to the transfer material as a part of the image, and image deterioration such as a vertical line on the image of the transfer material may occur. Also, in this blade type cleaning member,
There is a possibility that a positional shift of the toner image may occur due to a mechanical load caused by the contact of the blade. For this reason, in this type of image forming apparatus, in particular, an image forming apparatus using a belt-shaped image carrier, a cleaning unit equipped with the roller type or brush type cleaning member is often used.

However, in the roller-type or brush-type cleaning member, as described above, the transfer residual toner is electrically attracted and removed by the fur brush and the bias roller. It is difficult to remove the transfer residual toner charged to the same polarity as the polarity of the bias applied to the toner. For this reason, in the roller-type or brush-type cleaning member, for example, the polarity of the toner image is reversed by the transfer bias when the formed toner image is transferred onto the transfer material. In some cases, the transfer residual toner cannot be removed in some cases.

In order to solve such a problem, conventionally, a photosensitive member, a developing means for developing a latent image on the photosensitive member, and a bias potential difference generated by the high-voltage power supply for the developed toner image. An intermediate transfer member transferred by
Transfer means for transferring the toner image on the intermediate transfer body to a recording medium to output a final image; and cleaning means for electrically cleaning toner remaining on the intermediate transfer body without being transferred to the recording medium. In the image forming apparatus,
A toner removing means for mechanically removing toner on the surface of the photoreceptor from the photoreceptor; and a high-voltage power supply at a contact portion between the photoreceptor and the intermediate transfer body for removing residual toner having a polarity opposite to that of a cleaning bias which cannot be removed by the cleaning means. An image forming apparatus has been proposed in which the toner is transferred from the intermediate transfer member to the photosensitive member by the bias voltage, and the residual toner transferred to the photosensitive member is removed by the toner removing means (Japanese Patent Laid-Open No. 10-254251).

However, this image forming apparatus has the following problems. That is, in this image forming apparatus, first, the transfer residual toner on the intermediate transfer body that has not been reverse-transferred onto the photoreceptor in the primary transfer portion due to the image forming conditions remains on the intermediate transfer body as it is. The transfer residual toner remaining on the transfer member is transferred onto the transfer material at the time of the next image formation, and an image defect occurs. In particular, in a color image forming apparatus, a color toner image is usually formed by superimposing four color toner images of black, cyan, magenta, and yellow. If left as it is on the top, an image defect called color mixture occurs. Here, the reason that the transfer residual toner is not reverse-transferred onto the photoreceptor at the primary transfer portion is that discharge occurs in a minute gap between the photoreceptor of the primary transfer portion and the intermediate transfer member. It is considered that the reason is that the toner is charged to both positive and negative polarities, and the transfer residual toner having the same polarity as the charged polarity of the photoconductor does not move to the photoconductor side. Second, since all the transfer residual toner on the intermediate transfer body is collected by the cleaning member provided on the photoconductor side, the load on the cleaning unit on the photoconductor side increases.

Incidentally, as a method for preventing the problem of the image forming apparatus, before the transfer residual toner on the intermediate transfer member after the secondary transfer is cleaned by the cleaning member such as the bias roller or the fur brush, the cleaning member is removed. There is a method in which the polarity of the transfer residual toner is previously charged to a polarity that can be efficiently removed by the bias roller or the fur brush by a contact charging member to which a bias having a polarity opposite to the bias applied to the toner is applied. Thus, even if the transfer residual toner remaining on the intermediate transfer body is charged to both positive and negative polarities, the transfer residual toner can be completely collected by the cleaning member and the contact charging member on the intermediate transfer body side. Will be able to

[0009]

However, cleaning of the image carrier in this type of image forming apparatus needs to be performed after the toner image formed on the image carrier is transferred to the transfer material. Accordingly, the cleaning members such as the fur brush and the bias roller and the contact charging member complete the transfer of the toner image formed on the image carrier to the transfer material after the image formation on the image carrier is started. Until that time, it is necessary to be separated from the image carrier. When the image forming apparatus is a high-speed machine, the image forming speed is high and the linear speed of the image carrier is also high. Therefore, after the toner image on the image carrier is transferred to the transfer material, the fur brush is used. It is necessary to design so that a cleaning member such as a bias roller or the like and the contact charging member are immediately brought into contact with the image carrier to clean the transfer residual toner on the image carrier.

For this reason, as described above, when the contact charging member is provided independently of the cleaning member such as the fur brush and the bias roller, the cleaning member and the contact charging member are separately provided. This requires a contact / separation mechanism for quickly contacting / separating the cleaning unit, resulting in a problem that the cleaning unit becomes large and complicated. Further, when the cleaning member and the contact charging member are configured to be individually contacted and separated from each other, the number of components such as the contacting / separating mechanism and the holding frame increases, and the driving torque of the driving system increases. In addition, there is a problem that the cost of the cleaning unit is increased because the electric circuit of the control system becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an image forming apparatus having a cleaning unit having a small size and a simple structure at a low cost, having a high cleaning performance. That is.

[0012]

According to a first aspect of the present invention, a toner image formed on an image carrier is transferred to a transfer material and then contacted with the image carrier. A cleaning member for cleaning the transfer residual toner remaining on the image carrier by applying a bias having a polarity opposite to the charge polarity of the toner; and a cleaning member on the front side of the cleaning member with respect to the image carrier. And a contact charging member that contacts the image carrier and has a bias applied with a polarity opposite to the bias applied to the cleaning member when cleaning the transfer residual toner. In the image forming apparatus, the cleaning member and the contact charging member are provided in one cleaning unit.

In this image forming apparatus, since the cleaning member and the contact charging member are provided in one cleaning unit, the cleaning member and the contact charging member can be freely moved toward and away from the image carrier. Only one contact / separation mechanism or holding frame for holding is needed,
The structure of the cleaning unit is simplified. Further, many components of the drive system and the control system of the cleaning member and the contact charging member can be shared, the drive torque of the drive system is reduced, and the electric circuit of the control system is simplified. You.

According to a second aspect of the present invention, there is provided a toner collection container for a cleaning member for collecting the transfer residual toner cleaned by the cleaning member, and a toner collection container for collecting the transfer residual toner cleaned by the contact charging member. 2. The image forming apparatus according to claim 1, further comprising a toner collecting container for the contact charging member, wherein the toner collecting container for the cleaning member and the toner collecting container for the contact charging member are formed as one toner collecting container. It is characterized by having done.

In this image forming apparatus, the transfer residual toner cleaned by the cleaning member and the contact charging member is collected in one toner collecting container. Thereby, the structure of the cleaning unit is further simplified.

According to a third aspect of the present invention, there is provided a cleaning member, wherein the image carrier is constituted by an endless belt stretched rotatably, and is arranged to face the cleaning member with the image carrier interposed therebetween. 3. The image forming apparatus according to claim 1, further comprising: a counter roller for the contact member, and a counter roller for the contact charging member disposed to face the contact charging member with the image carrier interposed therebetween. And the opposing roller for the contact charging member is constituted by one opposing roller.

In the case where the image carrier is formed of an endless belt stretched rotatably, the endless belt is used to securely contact the image carrier with the cleaning member and the contact charging member. Roller for a cleaning member disposed to face the cleaning member with the belt in between, and a counter roller for a contact charging member disposed to face the contact charging member with the endless belt in between Is required. However, when the opposing roller for the cleaning member and the opposing roller for the contact charging member are separately arranged, the bias formed between the cleaning member and the contact charging member and the endless belt is unstable. Could be This seems to be due to the endless belt vibrating between the two opposing rollers which are individually arranged. In this image forming apparatus, since the opposing roller of the cleaning member and the opposing roller for the contact charging member are constituted by one opposing roller, the cleaning member and the contact charging member are disposed between the endless belt and the endless belt. The formed bias becomes stable. Further, the tension structure and the drive system of the endless belt are simplified.

According to a fourth aspect of the present invention, in the image forming apparatus of the first, second or third aspect, the contact charging member is constituted by a conductive brush.

In this image forming apparatus, since the contact charging member is formed of a conductive brush, the contact charging member contacts the image carrier when the contact charging member contacts the image carrier. The contact pressure is reduced, so that an excessive load is not applied to the image carrier.

According to a fifth aspect of the present invention, in the image forming apparatus of the first, second or third aspect, the contact charging member is formed of a conductive roller.

In this image forming apparatus, since the contact charging member is formed of a conductive roller, a transfer residual toner remaining on the image carrier is removed by applying a bias to the contact charging member. It becomes uniformly charged.

According to a sixth aspect of the present invention, in the image forming apparatus of the fifth aspect, the surface of the contact charging member is coated with a film having high releasability.

In this image forming apparatus, since the surface of the contact charging member is coated with a coating having high releasability, the amount of transfer residual toner adhered to the surface of the contact charging member is reduced, and With the cleaning member disposed downstream of the charging member, more transfer residual toner can be collected. As described above, since the amount of the transfer residual toner adhered to the surface of the contact charging member is reduced, a cleaning member such as a blade for cleaning the surface of the contact charging member becomes unnecessary.

[0024] The invention of claim 7 is based on claims 1, 2, 3,
In the image forming apparatus according to any one of 4, 5 and 6, when the transfer residual toner is cleaned by the cleaning member, a bias in which an AC component is superimposed on a DC component is applied to the cleaning member.

Depending on the polarity and amount of the transfer residual toner,
Although good cleaning may be performed even when the bias applied to the cleaning member is only the DC component,
For example, in the case of a transfer residual toner in which a plurality of color toners are overlapped, the transfer residual toner in the lower layer is less likely to move to the cleaning member side by applying a bias of only the DC component, and the cleaning property of the cleaning member is reduced. Sometimes. In this image forming apparatus, when a bias in which an AC component is superimposed on a DC component is applied to the cleaning member, the transfer residual toner is disturbed by the bias, and the transfer residual toner is removed from the image bearing member by the bias. It is easy to move to the cleaning member side, and the cleaning property of the cleaning member is improved.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a color image forming apparatus will be described below. FIG. 1 shows a schematic configuration of a color image forming apparatus according to the present embodiment.
This color image forming apparatus includes a photosensitive member 1 as a first image carrier, a charging device 2, an exposing device 3, a developing device 4, an intermediate transfer member 5 as a second image carrier, and a fixing device (not shown). )
Etc. are provided. In FIG. 1, a photoconductor 1 is made of an organic photoconductor formed in the form of an endless belt that is negatively charged, is stretched around a driving roller 1a and a driven roller 1b, and is driven to rotate at a predetermined speed in the direction of the arrow. The charging device 2 is applied with a predetermined bias and negatively charges the surface of the photoconductor 1 to a predetermined potential by contact (or non-contact). Exposure device 3
The photoreceptor 1 sequentially exposes image light of each color, which is color-separated based on image data read by an image reading unit (not shown), to form an electrostatic latent image of each color on the photoreceptor 1.

The developing device 4 includes four developing devices 4a, 4b, 4c, which individually store toners of yellow, magenta, cyan, and black, respectively, each having a normal toner polarity of negative polarity.
4d, and sequentially develops the electrostatic latent images of each color formed on the photoreceptor 1 by a developing device containing a toner of a color corresponding to the electrostatic latent image. A toner image of each color is formed thereon. The intermediate transfer member 5 is disposed so as to face the photoconductor 1, and is driven to rotate at a predetermined speed in the direction of the arrow. Then, in the primary transfer section A where the intermediate transfer member 5 and the photoconductor 1 face each other, the toner images of the respective colors formed on the photoconductor 1 are sequentially superimposed on the intermediate transfer member 5 and primary-transferred. . As a result, a color toner image is formed on the intermediate transfer member 5. The primary transfer residual toner remaining on the photoconductor 1 in this primary transfer step is removed by the photoconductor cleaning unit 6 disposed downstream of the primary transfer section A in the rotation direction of the photoconductor 1.
The photoconductor 1 is removed and collected.

Further, a transfer roller 5a as a secondary transfer means is disposed on the downstream side of the primary transfer portion A in the rotation direction of the intermediate transfer member 5 so as to face the transfer roller 5a. Then, a predetermined secondary transfer bias is applied to the transfer roller 5a at a secondary transfer portion B where the transfer roller 5a and the intermediate transfer body 5 face each other.
Paper 7 as a transfer material sent to the secondary transfer portion B
Then, the color toner image formed on the intermediate transfer member 5 is secondarily transferred. The color toner image secondarily transferred onto the paper 7 is fused and fixed onto the paper 7 by a fixing device (not shown). The sheet 7 on which the color toner image is formed in this way is discharged outside the apparatus as a color print.

After the color toner image is secondarily transferred to the sheet 7 as described above, the transfer residual toner remaining on the intermediate transfer member 5 is transferred to the secondary transfer portion B in the rotation direction of the intermediate transfer member 5. The intermediate transfer member is removed from the intermediate transfer member 5 and collected by the intermediate transfer member cleaning unit 8 disposed downstream of the intermediate transfer member. This intermediate transfer body cleaning unit 8
Includes a contact charging member 8a, a cleaning member 8b, a bias roller 8c, a cleaning blade 8d, and the like.

The contact charging member 8a is provided so as to be able to freely contact and separate from the intermediate transfer member 5, and comes into contact with the intermediate transfer member 5 at the time of cleaning the transfer residual toner so that a negative bias is applied. You. As a result, the transfer residual toner is charged to the negative polarity released from the intermediate transfer member 5, and the transfer residual toner is partially adhered to the contact charging member 8a side from the intermediate transfer member 5 and collected. The transfer residual toner not collected by the contact charging member 8a is charged to the negative polarity by the contact charging member 8a and moved toward the intermediate transfer body cleaning unit 8.

The cleaning member 8b of the intermediate transfer member cleaning unit 8 is provided at a position downstream of the contact charging member 8a in the rotation direction of the intermediate transfer member 5,
, And comes into contact with the intermediate transfer member 5 when the transfer residual toner is cleaned. Also,
A positive bias is applied to the cleaning member 8b by a bias roller 8c. The negative transfer residual toner not collected by the contact charging member 8a is
By contacting the cleaning member 8b, the toner is mechanically and electrically collected from the intermediate transfer member 5. And
The negative transfer residual toner collected by the cleaning member 8b is electrically moved to the positively charged bias roller 8c side, and then is transferred to the bias roller 8c.
The toner is mechanically scraped off from the bias roller 8c by a cleaning blade 8d disposed so as to come into contact with the toner cartridge c, and is collected in a toner collecting container described later.

Next, the result of evaluating the cleaning performance of the intermediate transfer body cleaning unit 8 will be described. This cleaning property was evaluated according to the following method. That is, during the formation of the toner images of the respective colors, the power supply is turned off to stop the image formation on the way, and
The remaining transfer residual toner image is transferred to a tape using an adhesive tape, and the density of four color toners of black, cyan, magenta, and yellow is measured by a reflection type spectral densitometer such as X-rite (trade name). The measurement was performed, and each concentration was set to I1. The result of measuring the density of each color at the time of blank paper is defined as I0,
The image density I of each color was left by the following equation. I = I1−I0... Here, if the amount of the residual toner remaining on the intermediate transfer body 5 is large, the density of the image transferred to the adhesive tape by the tape is considered to be high. The image density of each color was used as a measure of the residual toner amount.

FIG. 2 shows how the image density changes depending on whether or not the contact charging member 8a is provided on the upstream side of the cleaning member 8b of the intermediate transfer body cleaning unit 8. In FIG. 2, the mark ○ indicates the image density of the black toner K, the mark □ indicates the image density of the yellow toner Y, the mark △ indicates the image density of the magenta toner M, and the mark × indicates the image density of the cyan toner C. Further, the symbols a1, a2, and a3 on the horizontal axis of the graph shown in FIG. 2 indicate before cleaning (a1) when the transfer residual toner is cleaned by applying a positive bias to the cleaning member 8b.
The image densities b1, b2, and b3 after the cleaning (a2) and after the primary transfer (a3) are the same as those of the cleaning member 8 described above.
When a negative bias is applied to b to remove the transfer residual toner, the image density before cleaning (b1), after cleaning (b2), and after primary transfer (b3), c
1, c2, c3, the contact charging member 8a is disposed upstream of the cleaning member 8b, and the contact charging member 8a
A negative bias is applied to the cleaning member 8b, and a positive bias is applied to the cleaning member 8b.
2) shows the image density after the primary transfer (a3). As can be seen from FIG. 2, the provision of the contact charging member 8a on the upstream side of the cleaning member 8b significantly improves the cleaning performance of the intermediate transfer body cleaning unit 8.

When the contact charging member 8a is provided independently of the cleaning member 8b,
A plurality of contacting / separating mechanisms for quickly and separately contacting and separating the cleaning member 8b and the contact charging member 8a are required, and the intermediate transfer body cleaning unit becomes large and complicated. Also,
The number of components such as the contact / separation mechanism and the holding frame increases, so that the drive torque of the drive system increases, and the electric circuit of the control system becomes complicated, so that the cost of the intermediate transfer body cleaning unit 8 increases. .

Therefore, in the image forming apparatus according to the present embodiment, for example, the cleaning unit 1 shown in FIG.
As shown in FIG. 0, the cleaning member 11 composed of the fur brush and the bias roller and the contact charging member 14 composed of a metal roller and the like are arranged in one cleaning unit case 15. As a result, the cleaning member 11 and the contact charging member 14 can be simultaneously moved toward and away from the intermediate transfer belt 16 as the intermediate transfer body by one contact / separation mechanism, and the intermediate transfer belt cleaning unit The structure of 10 is simplified. Further, many of the components of the drive system and the control system for driving the cleaning member 11 and the contact charging member 14 can be shared, so that the cleaning member 11 and the contact charging member 14 can be shared as compared with a case where the cleaning member 11 and the contact charging member 14 are separately provided. The drive torque of the contact / separation mechanism is reduced, which is advantageous in terms of control circuit design and the like.

Here, a toner collecting container for the cleaning member 11 for collecting the transfer residual toner cleaned by the cleaning member 11 and a contact for collecting the transfer residual toner cleaned by the contact charging member 14. A toner collection container for the charging member 14;
When two are separately provided, the degree of freedom in designing the position and size of each toner collecting container is increased, but not only the size of the cleaning unit 10 is increased but also the cost is increased. As shown in FIG. 3, the cleaning unit 10 of the image forming apparatus according to the present embodiment is configured such that the transfer residual toner cleaned by the cleaning member 11 and the transfer residual toner cleaned by the contact charging member 14 It is configured to be collected in one toner collection container 18. As a result, the space and cost of the cleaning unit 10 can be reduced.

In FIG. 3, the intermediate transfer belt 16 is rotating and moving in the direction shown by the arrow. The transfer residual toner that enters the contact charging member 14 due to the rotational movement of the intermediate transfer belt 16 slightly passes through the secondary transfer roller 5a due to the positive bias applied to the secondary transfer roller 5a. It is charged to the positive (positive) side. Therefore, in the cleaning unit 10 of the image forming apparatus according to the present embodiment, a negative (minus) bias is applied to the contact charging member 14, and first, the transfer residual toner is electrically applied to the contact charging member 14. Collect by attaching. The transfer residual toner not collected by the contact charging member 14 is transferred to the cleaning member 11.
Collected at.

That is, the transfer residual toner that is not collected by the contact charging member 14 and enters the cleaning member 11 is injected with a negative charge by the bias applied to the contact charging member 14 and has a negative polarity. It is charged and rushes into the cleaning member 11. As a result, the transfer residual toner that has passed through the contact charging member 14 is removed from the cleaning member 11 to which the positive bias is applied.
Side of the cleaning member 11
Adheres to In this way, the transfer residual toner attached to the contact charging member 14 and the cleaning member 11 is scraped off from the contact charging member 14 and the cleaning member 11 by the flip covers 12a and 12b shown in FIG. The toner is collected in the toner collecting container 18.

The transfer residual toner collected in the toner collecting container 18 is transferred by a toner collecting roller 13 such as a screw disposed in the toner collecting container 18.
The toner is conveyed to a toner collection bottle (not shown) and collected.
The transfer residual toner that has passed through the cleaning member 11 without adhering to the cleaning member 11 is injected with a positive charge by a positive bias applied to the cleaning member 11, and is exposed to light by the primary transfer portion A. After the reverse transfer to the body 1, the photoconductor cleaning unit 6
Collected by

By the way, the cleaning unit 10
When cleaning the intermediate transfer belt 16 formed of an endless belt as described in the above, in order to make the cleaning member 11 and the contact charging member 14 surely contact the intermediate transfer belt 16, It is necessary to dispose an opposing roller at a position opposing the cleaning member 11 and the contact charging member 14 with the intermediate transfer belt 16 interposed therebetween. However, as shown in FIG.
When the opposing roller 17a opposing the cleaning member 11 and the opposing roller 17b opposing the cleaning member 11 are separately arranged, the vibration of the intermediate transfer belt 16 causes the cleaning member 11, the contact charging member 14, and the
May become unstable. Further, there is a possibility that the tension structure and the driving system of the intermediate transfer belt 16 are complicated.

Therefore, in the image forming apparatus according to the present embodiment, for example, as shown in FIG. 4, a facing roller facing the cleaning member 11 and the contact charging member 14 with the intermediate transfer belt 16 interposed therebetween is used. It is composed of one opposed roller 19 having a relatively large curvature. This allows
The intermediate transfer belt 16 does not vibrate between the cleaning member 11 and the contact charging member 14, and the bias formed between the cleaning member 11 and the contact charging member 14 and the intermediate transfer belt 16 is stabilized. Also,
The tension structure and drive system of the intermediate transfer belt 16 are also simplified.

Here, as the contact charging member 14,
A conductive brush can be used. As the conductive brush, for example, as shown in FIG. 5, a roller-shaped conductive brush 20 in which a pile woven brush is spirally wound around a steel shaft or an aluminum pipe as a core material can be used. Acrylic / carbon / nylon / carbon, polyester / carbon / polypropylene / carbon, or the like can be used as the fiber of the brush material of the conductive brush 20. As described above, the conductive brush 20 is used as the contact charging member 14, the conductive brush 20 is rotated in contact with the intermediate transfer belt 16, and the transfer residual toner remaining on the intermediate transfer belt 16 is removed. By cleaning, the transfer residual toner can be collected electrically and mechanically.

Further, as the contact charging member 14, for example, a conductive roller 21 as shown in FIG. 6 can be used. The conductive roller 21 is formed by forming a coating layer 21b made of rubber, resin, or the like on a core material 21a, such as a steel shaft or an aluminum pipe, by various coating methods. The conductive roller 21 having such a configuration
Is used as a charging device 2 for uniformly charging the surface of the photoreceptor 1 in the longitudinal direction, and is known as a contact-type charging unit with less occurrence of uneven charging. Therefore, by using the conductive roller 21 having such a configuration as the contact charging member 14, the intermediate transfer belt 1
The transfer residual toner remaining on the transfer roller 6 can be uniformly charged in the longitudinal direction without unevenness, so that the cleaning performance of the cleaning unit 10 can be improved.

As the contact charging member 14, for example, as shown in FIG.
It is preferable to use one coated with No. 2. By coating the surface of the contact charging member 14 with the coating film 22 having high releasability, the amount of transfer residual toner adhering to the surface of the contact charging member 14 is reduced, and the surface of the contact charging member 14 is cleaned. There is no need to provide a cleaning member such as a blade. As a coating material for forming the coating 22, rubber, elastomer,
Resins. Specifically, rubber, natural rubber as an elastomer, isoprene rubber, styrene butadiene rubber, butadiene rubber, butyl rubber, butadiene rubber,
Ethylene-propylene rubber, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylonitrile butadiene rubber, urethane rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, fluorine rubber, polysulfide rubber, polynorbornene rubber, hydrogenated nitrile rubber, polystyrene And thermoplastic elastomers such as polyolefins, polyvinyl chlorides, polyurethanes, polyamides, polyesters, and fluororesins. As the resin, polystyrene, chloropolystyrene, methyl methacrylate resin, butyl methacrylate resin, ethyl acrylate resin, butyl acrylate resin, modified acrylic resin, vinyl chloride resin, maleic acid resin, phenol resin, epoxy resin, polyester resin, Examples include, but are not limited to, polyurethane resins, polyethylene, polypropylene, polybutadiene, polyvinylidene chloride, ionomer resins, silicone resins, fluororesins, ketone resins, polyamide resins, polyphenylene oxide resins, and the like. These may be used alone or in combination of one or two kinds as a copolymer. Examples of the coating method of the film 22 include a dipping method, a spray coating method, a blade coating method, a beam coating method, and a roll coating method. It is necessary to select an appropriate method according to the properties of the coating material. If several types of coating methods can be used, any of these methods may be used.

The bias applied to the cleaning member 11 is desirably a bias in which an AC component is superimposed on a DC component. In other words, depending on the polarity and amount of the transfer residual toner after the secondary transfer, good cleaning may be performed by applying a bias of only the DC component. In the case of (1), when the bias is applied only with the DC component, the transfer residual toner in the lower layer becomes difficult to move to the cleaning member side, and the cleaning property of the cleaning member may be reduced. Therefore, the bias applied to the cleaning member 11 is a bias in which an AC component is superimposed on a DC component. Thereby, the transfer residual toner is disturbed by the bias, the transfer residual toner is easily moved to the cleaning member 11 side, and the cleaning property of the cleaning member 11 is improved.

The image forming apparatus according to the present embodiment
This shows an example in which a negatively charged photoconductor using reversal development and a negatively charged toner are used, but the polarity of the applied voltage and the like are not limited thereto. Further, the photoreceptor and the intermediate transfer member may be either a drum-shaped or a belt-shaped. Further, the present invention is applicable not only to a color image forming apparatus but also to a monochrome image forming apparatus.

[0047]

According to the first to seventh aspects of the present invention, since the cleaning member and the contact charging member are provided in one cleaning unit, the contact / separation mechanism and the holding mechanism between the cleaning member and the contact charging member are provided. Only one frame or the like is required, and the cleaning unit can be simplified. Further, many components of the drive system and the control system of the cleaning member and the contact charging member can be shared, so that the drive torque of the drive system can be reduced and the electric circuit of the control system can be simplified. There is an excellent effect that it can be done.

In particular, according to the second aspect of the present invention, since the transfer residual toner cleaned by the cleaning member and the contact charging member is collected in one toner collection container, the structure of the cleaning unit is further simplified. There is an excellent effect that can be made.

According to the third aspect of the present invention, since the opposing roller for the cleaning member and the contact charging member is constituted by one opposing roller, a stable bias can be applied and the number of parts can be reduced. There is an excellent effect that you can.

According to the fourth aspect of the present invention, since the conductive brush is used as the cleaning member, good toner collection can be performed without excessively applying an excessive load to the intermediate transfer member. There is an excellent effect that an excellent image formation can be performed.

According to the fifth aspect of the present invention, since the conductive roller is used as the cleaning member, the untransferred toner is uniformly charged, so that good toner recovery can be performed, and the occurrence of poor cleaning is reduced. There is an excellent effect that good image formation can be performed.

According to the sixth aspect of the present invention, since the surface of the contact charging member is coated with a film having high releasability, the amount of transfer residual toner adhering to the surface of the contact charging member is reduced. With the cleaning member disposed downstream of the contact charging member, more transfer residual toner can be collected. Further, since the amount of transfer residual toner adhering to the surface of the contact charging member is reduced, there is an excellent effect that a cleaning member such as a blade for cleaning the surface of the contact charging member becomes unnecessary.

According to the seventh aspect of the present invention, since the bias applied to the cleaning member is a bias in which the AC component is superimposed on the DC component, the transfer residual toner image is disturbed.
There is an excellent effect that good cleaning can be performed by the cleaning member.

[Brief description of the drawings]

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

FIG. 2 is a graph showing a result of evaluating the cleaning performance of a cleaning unit of the image forming apparatus.

FIG. 3 is a schematic configuration diagram of the cleaning unit.

FIG. 4 is another schematic configuration diagram of the cleaning unit.

FIG. 5 is a schematic perspective view of a conductive brush used in the cleaning unit.

FIG. 6 is a schematic configuration diagram of a conductive roller used in the cleaning unit.

FIG. 7 is a schematic configuration diagram of a contact charging member used in the cleaning unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 1a drive roller 1b driven roller 2 charging device 3 exposure device 4 developing device 4a yellow developing device 4b magenta developing device 4c cyan developing device 4d black developing device 5 intermediate transfer member 5a secondary transfer roller 6 photoconductor cleaning unit 7 paper Reference Signs List 8 Intermediate transfer member cleaning unit 8a Contact charging member 8b Cleaning member 8c Bias roller 8d Cleaning blade 10 Cleaning unit 11 Cleaning members 12a, 12b Flip cover 13 Toner collection roller 14 Contact charging member 15 Cleaning unit case 16 Intermediate transfer belt 17a, 17b Roller 18 Toner recovery container 19 Opposite roller 20 Conductive brush 21 Conductive roller 22 Film A Primary transfer section B Secondary transfer section

Claims (7)

[Claims] After a toner image formed on an image bearing member is transferred onto a transfer material, a bias is applied to the image bearing member in contact with the image bearing member and having a polarity opposite to the charging polarity of the toner. A cleaning member for cleaning the transfer residual toner remaining on the carrier; and a cleaning member that comes into contact with and separates from the image carrier at a position closer to the front side than the cleaning member. An image forming apparatus comprising: a contact charging member that is in contact with the image carrier and to which a bias having a polarity opposite to that of the bias applied to the cleaning member is applied, wherein the cleaning member and the contact charging member are connected to one another. An image forming apparatus provided in a cleaning unit. 2. A toner collection container for a cleaning member for collecting the transfer residual toner cleaned by the cleaning member, and a contact collection member for collecting the transfer residual toner cleaned by the contact charging member. 2. The image forming apparatus according to claim 1, further comprising a toner collecting container, wherein the toner collecting container for the cleaning member and the toner collecting container for the contact charging member are constituted by one toner collecting container. Image forming apparatus. 3. An opposing roller for a cleaning member, wherein the image carrier is constituted by an endless belt stretched rotatably, and arranged to face the cleaning member with the image carrier interposed therebetween. 3. The image forming apparatus according to claim 1, further comprising: an opposing roller for a contact charging member disposed so as to face the contact charging member with the image carrier interposed therebetween. An image forming apparatus comprising: an opposing roller for a contact charging member; and an opposing roller. 4. The image forming apparatus according to claim 1, wherein the contact charging member is formed of a conductive brush. 5. An image forming apparatus according to claim 1, wherein said contact charging member is constituted by a conductive roller. 6. The image forming apparatus according to claim 5, wherein the surface of said contact charging member is coated with a coating having high releasability. 7. The image forming apparatus according to claim 1, wherein the cleaning member removes the transfer residual toner by applying a DC component to the cleaning member.
An image forming apparatus, wherein a bias in which components are superimposed is applied.