JP4461768B2 - Image forming apparatus - Google Patents

Description

The present invention is a copying machine, relates to an image forming apparatus such as a printer, in particular, relates to an image forming apparatus having an improved cleaning device for cleaning the residue of the toner and the like remaining on the belt-shaped carrier.

  In recent years, in an image forming apparatus such as a copying machine or a printer using an electrophotographic system, for example, an intermediate transfer type image forming apparatus using an electrophotographic system is taken as an example. Are sequentially formed, and after primary transfer of each color component toner image to a belt-like carrier used as an intermediate transfer member, the multiple transfer toner images on the belt-like carrier are collectively transferred to the recording material. In order to obtain color images, proposals have already been made.

In this type of image forming apparatus, if the residue remaining on the belt-shaped conveyance body after the secondary transfer is left as it is, the image formed on the belt-shaped conveyance body next becomes dirty. For this reason, a cleaning device using a cleaning blade is disposed on the belt-like transport body in order to remove residues.
Further, in the image forming apparatus, since the toner has a small particle size and a spherical shape in order to obtain a high quality image, it is necessary for the cleaning blade to increase the pressure in order to ensure the cleaning performance. is there. As a result, the surface of the belt-shaped transport body is worn and the image quality is deteriorated, the durability of the belt-shaped transport body is also deteriorated, and the belt-shaped transport body is stretched due to excessive pressure of the cleaning blade. Color misregistration occurs.
In order to solve the above problem, the following prior art has been proposed.

  For example, an auxiliary drive (drive roll) that increases the conveyance force of the intermediate transfer belt (corresponding to the belt-shaped conveyance body in this case) is provided at the time of pressure contact with the cleaning blade. However, there is a proposal to reduce the color misregistration by preventing the slip between the auxiliary drive and the intermediate transfer belt due to the pressure contact of the cleaning blade by setting the speed fast (see, for example, Patent Document 1).

  In addition, by applying a voltage having the same polarity as the charging polarity of the toner adhering to the intermediate transfer member (corresponding to the belt-like conveyance member in this case) to the brush and the intermediate transfer member of the cleaning device, An electrostatic repulsive force is generated between the toner and the electrostatic force acting between the toner on the intermediate transfer member and the intermediate transfer member. Thus, there is a proposal to make it easier to scrape off the toner with a cleaning blade and reduce scratches and abrasion on the surface of the intermediate transfer member (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 8-286588 (page 3-6, FIG. 2) JP-A-8-262879 (page 5-8, FIG. 1)

However, the following technical problems are found in the above-described prior art.
For example, in Patent Document 1, it is necessary to add drive transmission for auxiliary drive, which is disadvantageous in terms of space and cost.
In addition, it is necessary to match the timing of the pressure contact of the cleaning blade to the intermediate transfer belt with the start of driving of the auxiliary drive. If this timing is shifted, color shift occurs.
Further, when the intermediate transfer belt is an elastic body, the intermediate transfer belt expands and contracts depending on the position of auxiliary driving, and color misregistration occurs.
Also in Patent Document 2, the intermediate transfer member is stretched due to the pressure contact of the cleaning blade, and the color misregistration is deteriorated depending on the rotation direction and rotation speed of the brush.

The present invention has been made to solve the above technical problem, and provides an image forming apparatus that prevents the belt-like conveyance body from extending while maintaining the cleaning performance.

That is, as shown in FIG. 1, the present invention is a belt-like transport body having an elastic layer that is driven and transported by a drive system and is carried on a plurality of stretching rolls 1 to carry and transport an image or a recording material. 2, an image forming apparatus having a cleaning device 3 for cleaning the belt-shaped carrier 2, a cleaning apparatus 3, and extends across the width direction orthogonal to the moving direction of the belt-shaped carrier 2 in the plate A cleaning plate-like member 4 whose tip is in contact with and away from the belt-like transport body 2 and a cleaning rotator 5 that is in contact with and away from the belt-like transport body 2 and rotates in the same direction as the moving direction of the belt-like transport body 2 when in contact. Further, a rotating body facing member 7 disposed in contact with the back surface of the belt-shaped transport body 2 facing the cleaning rotating body 5 with the belt-shaped transport body 2 interposed therebetween, and the cleaning rotating body 5 is transported in a belt shape. body A rotational driving force is applied to the cleaning rotator 5 and the rotator-opposing member 7 is driven in an auxiliary manner along the moving direction of the belt-like transport body 2 with the cleaning rotator 5 as a drive source. in, belt via said cleaning rotary body 5 and the rotary member facing member 7 gives the auxiliary conveying force to the belt-shaped carrier 2, generated with the contact and separation of the cleaning plate-like member 4 with respect to the belt-shaped carrier 2 And an expansion / contraction control means 6 that cancels out the expansion and contraction of the sheet-like transport body 2.

  In such technical means, the plurality of stretching rolls 1 may be appropriately selected from a driving roll and a driven roll. For example, one stretching roll 1 is used as a driving roll and the other stretching roll 1 is driven. In the system in which the belt-like transport body 2 is driven to follow, all the tension rolls 1 may be driven rolls.

Further, the belt-like transport body 2 is not limited to a mode in which an image is carried and conveyed, and includes a mode in which a recording material is carried and conveyed.
Here, examples of the mode in which the image is carried and conveyed include a photosensitive belt and a dielectric belt on which the image is formed and carried, and an intermediate transfer belt on which the formed image is primarily transferred and held. As an aspect in which the recording material is carried and conveyed, for example, a recording material conveying belt of a so-called tandem type image forming apparatus in which images formed by a plurality of image forming units are sequentially transferred onto the recording material can be cited.

  As an image forming method used in the image forming apparatus of the present case, for example, an electrophotographic method, an electrostatic recording method, or the like is used, and a recording material carried directly on the belt-like carrier 2 or on the belt-like carrier 2. As for the image transfer method, a method in which the formed image is transferred to the belt-like carrier 2 or the recording material via a transfer means, as in the electrophotographic method or the electrostatic recording method, is mainly used.

The cleaning plate-like member 4 is a plate-like member that extends in the width direction perpendicular to the moving direction of the belt-like transport body 2 and is appropriately selected as long as the tip portion contacts the belt-like transport body 2. For example, a cleaning blade or a scraper may be used.
Note that a cleaning bias may be applied to the cleaning plate-like member 4 so that the residue (for example, residual toner) T on the belt-like conveyance body 2 is electrostatically adsorbed.

Further, the cleaning rotator 5 may be appropriately selected as long as it is in contact with the belt-shaped transport body 2 and rotates in the same direction as the movement direction of the belt-shaped transport body 2, for example, conductive fibers Examples thereof include a brush and a brush roll that mechanically removes the residue T by rotating at high speed, and a magnetic roll that removes the residue T magnetically.
Here, the relative positional relationship between the cleaning plate-like member 4 and the cleaning rotator 5 may be arbitrarily set, and the cleaning rotator 5 is located downstream of the cleaning plate-like member 4 in the moving direction of the belt-like transport body 2. Or any of the upstream side may be sufficient.

The expansion / contraction control means 6 is appropriately selected as long as it applies an auxiliary conveyance force to the belt-like conveyance body 2 through at least the cleaning rotator 5 and cancels the elongation of the belt-like conveyance body 2 by this auxiliary conveyance force. There is no problem. Here, the auxiliary conveying force is not limited to mechanical force such as rigidity, friction coefficient, and biting amount of each material, but electrostatic force by applying a bias or a combination of both. Etc. are arbitrary.
Among the expansion / contraction control means 6, a typical mode in which the auxiliary conveying force is a mechanical force includes one that gives at least a rotational driving force to the cleaning rotator 5. This is an aspect obtained by appropriately controlling a drive source such as a motor. For example, the cleaning rotary body 5 is rotated in the same direction as the moving direction of the belt-like transport body 2 by a control signal from the expansion / contraction control means 6. The extension of the belt-like conveyance body 2 on the downstream side from the cleaning plate-like member 4 may be canceled out.

Further, the expansion / contraction control means 6 may provide a rotational driving force only to the cleaning rotator 5, but may also apply a driving force to members other than the cleaning rotator 5 to cancel expansion / contraction of the belt-like transport body 2. Good.
Here, if the expansion / contraction control means 6 is a mode in which the rotational driving force is applied only to the cleaning rotator 5, the expansion / contraction control means 6 needs to set the peripheral speed of the cleaning rotator 5 within a range where the cleaning performance is established.
For example, when the pressure of the cleaning plate-like member 4 against the belt-like transport body 2 is increased in order to improve the cleaning performance, the expansion / contraction control means 6 increases the peripheral speed of the cleaning rotary body 5 from the viewpoint of preventing color misregistration. The belt feeding performance of the cleaning rotator 5 needs to be increased.
This is a direction to further improve the cleaning performance, and the two do not conflict.

Further, the peripheral speed of the cleaning rotator 5 may be appropriately selected from the viewpoint of keeping the color registration deviation within an allowable range, but the cleaning rotator 5 usually has a mode in which a cleaning bias is applied. In consideration of electrostatic adhesion to the belt-shaped carrier 2, it is preferable to set it to 1.5 times or more the peripheral speed of the belt-like carrier 2.
That is, even if the peripheral speed of the cleaning rotator 5 is set to be equal to or higher than the peripheral speed of the belt-shaped transport body 2, if the difference in peripheral speed is small, the cleaning rotator 5 is moved to the belt-shaped transport body 2. From the standpoint of keeping the color registration misalignment within an allowable range, the difference between the peripheral speeds was examined, and the relationship between the peripheral speed differences described above was obtained.
However, as described later, in the aspect using the auxiliary driving member, it is not always necessary that the peripheral speed difference between the cleaning rotating body 5 and the belt-shaped transport body 2 is the above-described relationship.

Further, due to concerns such as wear on the surface of the belt-shaped transport body 2, a situation may occur in which the peripheral speed of the cleaning rotating body 5 cannot be increased to a range where the elongation of the belt-shaped transport body 2 due to the load of the cleaning plate-like member 4 is canceled. In such a situation, it is only necessary to apply a driving force to members (auxiliary driving members) other than the cleaning rotator 5 so as to cancel out the expansion and contraction of the belt-like conveyance body 2.
Here, as the auxiliary driving member, there is a tension roll 1 (for example, a tension roll 1 positioned on the downstream side in the movement direction of the belt-shaped transport body 2 with respect to the cleaning rotating body 5). For example, when the cleaning rotator 5 is in pressure contact with the belt-shaped transport body 2, it is preferable to drive the belt-shaped transport body 2 in the moving direction.
At this time, the driving force of the cleaning rotator 5 and the stretching roll 1 can cancel the load of the cleaning plate member 4 on the belt-shaped transport body 2, and the elongation of the belt-shaped transport body 2 is cancelled.

Further, a mode in which a rotating body facing member 7 is disposed in contact with the back surface of the belt-shaped transport body 2 facing the cleaning rotating body 5 with the belt-shaped transport body 2 interposed therebetween is often used, for example, the cleaning rotating body 5 and the rotating body. A configuration in which a predetermined cleaning bias is applied between the opposing member 7 is employed.
In such an embodiment, from the viewpoint of canceling out the elongation of the belt-shaped transport body 2 efficiently, the rotating body facing member 7 is used as the auxiliary driving member. As the rotating body facing member 7, the cleaning rotating body 5 is a belt. When the belt-shaped transport body 2 is pressed against the belt-shaped transport body 2, it is preferable to drive the belt-shaped transport body 2 in an auxiliary direction.

Here, the rotating body facing member 7 may be appropriately selected as long as the rotating body facing member 7 is disposed on the back surface side of the belt-shaped transport body 2 in the facing portion between the cleaning rotating body 5 and the belt-shaped transport body 2. For example, From the viewpoint of reducing the frictional force, a roll shape is preferable. Further, the rotating body facing member 7 may be in a state of always contacting the belt-shaped transport body 2, or may be pressed and separated simultaneously with the cleaning rotating body 5.
In this way, by driving the rotating body facing member 7 facing the cleaning rotating body 5, the load caused by the cleaning plate-like member 4 can be canceled out, and the elongation of the belt-shaped transport body 2 can be canceled out efficiently.

Further, in the aspect in which the cleaning rotator 5 and the rotator facing member 7 are driven as described above, a drive source may be provided in the rotator facing member 7, but from the viewpoint that a drive source is not provided separately. For example, the rotating body facing member 7 is preferably driven using the cleaning rotating body 5 as a drive source.
For example, a gear is provided at the ends of the cleaning rotator 5 and the rotator-opposing member 7, and the driving force of the cleaning rotator 5 can be transmitted to the rotator-opposing member 7 by meshing the gears. Thus, the rotating body facing member 7 may be driven.
In this case, since the drive timing of the cleaning rotator 5 and the rotator facing member 7 is the same, it is preferable in that adverse effects such as a color shift due to a shift in the drive timing do not occur.

Further, from the viewpoint of ensuring cleanliness against dirt on the surface of the belt-shaped transport body 2, the belt-shaped transport body 2 preferably has a multilayer structure in which a release layer is laminated on at least the surface of the elastic layer.
Furthermore, from the viewpoint of preventing slippage of the belt-shaped transport body 2 due to rotation of the cleaning rotating body 5 and the rotating body-facing member 7, the Young's modulus is 30 MPa or less as a physical property value of the elastic layer of the belt-shaped transport body 2. It is preferable.
Furthermore, from the viewpoint of maintaining transferability, the volume resistance of the elastic layer of the belt-like transporter 2 is preferably 10 ⁴ Ω or more and 10 ¹⁰ Ω or less.

Further, the material of the belt-shaped transport body 2 is soft-cured due to environmental fluctuations such as temperature and humidity, and the degree of expansion and contraction also changes. For this reason, from the viewpoint of changing the peripheral speed of the cleaning rotator 5 in accordance with the environment, the expansion / contraction control means 6 detects the peripheral speed of the belt-shaped transport body 2 by detecting the peripheral speed of the belt-shaped transport body 2. Detection means for detecting the expansion / contraction state, control means for controlling the rotation state of the cleaning rotator 5 based on a detection result by the detection means, and driving for driving the cleaning rotator 5 based on a control signal from the control means Means.
For example, when the detection means detects the elongation of the belt-like transport body 2 due to a temperature rise, the control means may change the peripheral speed of the cleaning rotator 5.
The control means may be appropriately selected as long as it changes the number of rotations of the cleaning rotator 5 based on the detection result of the detection means, and examples thereof include control by a computer.

Furthermore, in the aspect in which the detection means detects the state of the belt-shaped transport body 2, the detection means is the belt-shaped transport body when the cleaning plate-like member 4 and the cleaning rotating body 5 are pressed against and separated from the belt-shaped transport body 2. The peripheral speed of 2 may be detected.
For example, there is a method in which a reflective seal is provided outside the image forming range on the belt-like conveyance body 2 to detect one rotation speed of the belt-like conveyance body 2 when the cleaning plate-like member 4 and the cleaning rotator 5 are pressed and separated. Can be mentioned.

Further, the auxiliary conveyance force applied to the belt-like conveyance body 2 by the expansion / contraction control means 6 is not limited to the mechanical force as described above, and may include an electrostatic force.
Here, as a typical aspect of the expansion / contraction control means 6 in which an electrostatic force is included in the auxiliary conveyance force, one that includes applying an electrostatic field between the cleaning rotating body 5 and the belt-like conveyance body 2 is included. Can be mentioned. This includes any combination of mechanical force and electrostatic force as well as an aspect of only electrostatic force as long as the auxiliary conveying force includes electrostatic force. Further, “acting an electrostatic field” is intended to include not only a mode in which a bias is applied to the cleaning rotator 5 but also a mode in which a bias is applied to the opposing member side.
According to such an aspect, the belt-like conveyance body 2 can be electrostatically attracted to the cleaning rotator 5 and an auxiliary conveyance force can be applied to the belt-like conveyance body 2.

  Furthermore, as another aspect of the expansion / contraction control means 6 in which an electrostatic force is included in the auxiliary conveyance force, there is one that includes applying an electrostatic field between the cleaning plate-like member 4 and the belt-like conveyance body 2. Can be mentioned. This assumes a mode in which a bias is applied to the cleaning plate-like member 4. When an electrostatic field is applied to the cleaning plate-like member 4 side, the electrostatic adsorption action causes the cleaning plate-like member 4 and the belt shape. Since the space between the transport bodies 2 is further extended, it is necessary to increase the auxiliary transport force to the belt transport body 2 by the cleaning rotating body 5 accordingly.

In addition, as a variation factor of the mechanical force or the electrostatic force as the auxiliary conveyance force, a shape, an assembly error, and an environment variation can be considered.
Mechanical forces have little effect on environmental fluctuations, but are highly sensitive to manufacturing and assembly errors. On the other hand, electrostatic force is less sensitive to manufacturing and assembly errors, but environmental fluctuations are affected by fluctuations in the electrical resistance of the material and the voltage value or current value changes. Along with this, the electrostatic force (electrostatic adsorption force) due to the electrostatic field also changes.
At this time, since the reduction of the error with respect to the mechanical force mainly depends on the improvement of accuracy, it is disadvantageous in terms of cost. Therefore, in an embodiment that relies on mechanical force, it is difficult to provide a predetermined performance at a low cost due to tolerance variation. In this regard, it is necessary to cope with environmental fluctuations for electrostatic forces, but the electrostatic field can be changed at any time by adjusting the voltage and current settings to the environment, which is advantageous in terms of cost. is there.
From this point of view, the expansion / contraction control means 6 changes the electrostatic field formed between the cleaning member composed of the cleaning rotator 5 or the cleaning plate member 4 and the belt-like transport body 2 according to the environment. Those are preferred. As described above, since the electrostatic field is likely to change according to environmental changes (mainly temperature changes), it is necessary to change the electrostatic field according to the environment in order to set a more accurate auxiliary transport force. .

In addition, the material of the belt-like transport body 2 is soft-cured due to environmental fluctuations such as temperature and humidity, and the expansion / contraction characteristics change even under the same load condition. For this reason, from the viewpoint of changing the electrostatic field between the cleaning member and the belt-like transport body 2 according to the environment, the expansion / contraction control means 6 is a detection means for detecting the stretched state of the belt-shaped transport body 2. And a control means for controlling an electrostatic field formed between the cleaning member comprising the cleaning rotator 5 or the cleaning plate member 4 and the belt-like transport body 2 based on a detection result by the detection means, and the control means And a power source that causes the electrostatic field to act on the basis of a control signal.
At this time, as a detection means, when the cleaning plate-like member 4 and the cleaning rotator 5 are pressed against and separated from the belt-like carrier 2, the peripheral speed of the belt-like carrier 2, for example, one round of the belt-like carrier 2 is detected. It is effective to set an optimum applied voltage or supply current or to select a parameter by a parameter table by detecting the rotation time of the current and comparing it with the control means.

Moreover, in the aspect using an electrostatic force as the auxiliary conveyance force applied to the belt-shaped conveyance body 2, it is preferable that the cleaning rotator 5 has a brush shape. The brush-like cleaning rotator 5 is effective in cleaning performance, has low sensitivity to the influence on the belt-like transport body 2, and can be less affected by variations in setting conditions.
Here, since the brush-like cleaning rotating body 5 generally has a large manufacturing error, the configuration relying on mechanical force as the auxiliary conveying force to the belt-like conveying body 2 has a large variation in the auxiliary conveying force. The electrostatic force varies little with respect to manufacturing and assembly variations, and variation in the auxiliary conveying force can be suppressed to a small value.
In particular, as a preferred embodiment of the brush-like cleaning rotator 5, a brush yarn having a small mechanical force and a Young's modulus of 2500 cN / mm ² or less is desirable, and an electrostatic force (electrostatic adsorption force) is effective. Therefore, it is desirable that the brush yarn resistance is 10 ⁴ Ω · cm or more and 10 ¹⁰ Ω · cm or less.

Although the present invention is directed to the image forming apparatus , the cleaning device 3 used therefor may be constructed as a related invention related to the present invention.
In this case, as shown in FIG. 1, the related invention related to the present invention is an elastic layer which is driven and conveyed by a drive system and is carried on a plurality of stretching rolls 1 to carry and convey an image or a recording material. In the cleaning device 3 for cleaning the belt-shaped transport body 2 having a cleaning plate, the cleaning plate extends in a plate shape across the width direction orthogonal to the moving direction of the belt-shaped transport body 2 and the front end portion contacts and separates from the belt-shaped transport body 2 A belt-like conveying member 4, a cleaning rotator 5 that contacts and separates from the belt-like carrier 2 and rotates in the same direction as the movement direction of the belt-like carrier 2 at the time of contact, and at least the cleaning rotator 5 There is provided expansion / contraction control means 6 that applies an auxiliary conveying force to the body 2 and offsets the expansion / contraction of the belt-like conveyance body 2 that occurs when the cleaning plate-like member 4 contacts and separates from the belt-like conveyance body 2 at least. It may be set to so that.

Next, the operation of the cleaning device 3 in the above-described image forming apparatus will be described.
For example, in an intermediate transfer type color image forming apparatus, the cleaning plate-like member 4 and the cleaning rotator 5 are pressed against the belt-like carrier 2 after the final color is transferred, and clean the residual toner T. Therefore, during continuous printing, the cleaning plate-like member 4 and the cleaning rotator 5 are in pressure contact with the belt-like conveyance body 2 only during the image formation of the first and subsequent colors.
At this time, the belt-like conveyance body 2 is in an extended state due to the pressure of the cleaning plate-like member 4 on the downstream side of the cleaning plate-like member 4 in the moving direction of the belt-like conveyance body 2. While the color image transferred in this state is transferred with the belt-like transport body 2 extended, the other color image is transferred with the belt-like transport body 2 in a normal state, so that color misregistration occurs.
Therefore, by applying an auxiliary conveyance force (mechanical force and / or electrostatic force) to the belt-like conveyance body 2 through at least the cleaning rotator 5, the elongation of the belt-like conveyance body 2 is reduced and the belt-like conveyance body 2 is reduced. The expansion and contraction of the transport body 2 is offset to bring it into a normal state.
Thereby, it is possible to obtain a good image without color misregistration while maintaining the cleaning performance.

As described above, according to the image forming apparatus of the present invention, the cleaning plate-like member whose tip is in contact with and separated from the belt-like carrier that is driven and conveyed by the drive system and has the elastic layer, and the belt-like member a cleaning rotary body rotating in the same direction as the moving direction of the belt-like carrier upon contact apart and in contact with the member provided further contact with the belt-shaped carrier back surface opposed to the cleaning rotary member across the belt-shaped carrier arrangement When the cleaning rotator is brought into pressure contact with the belt-like transport body, a rotational driving force is applied to the cleaning rotator, and the rotating body-facing member is rotated for cleaning along the moving direction of the belt-like transport body. by supplementarily drives the body as a driving source, giving an auxiliary conveying force to the belt-shaped carrier via the cleaning rotating body and the rotating body facing member, against the belt-shaped carrier Since such comprises expansion control means to offset the expansion and contraction of the belt-shaped carrier generated with the contact and separation of that cleaning plate-like member, the auxiliary conveying force applied to the belt-shaped carrier, the cleaning plate-like member and The elongation of the belt-like conveyance member due to the rotating member-facing member can be canceled out, and a good image without color misregistration can be obtained while maintaining the cleaning performance.

Here, in the present invention, as the auxiliary conveyance force applied to the belt-shaped conveyance body, either a mechanical force or an electrostatic force may be mainly used. This is preferable in that the auxiliary conveying force can be adjusted accurately because the influence of manufacturing and assembly errors (the cleaning rotating member or the cleaning plate member) is small.
However, since the electrostatic force is likely to be affected by environmental fluctuations, a mode in which correction is made according to environmental changes is preferable.

Further, in the present invention, in an aspect where the auxiliary conveyance force applied to the belt-shaped conveyance body is insufficient only with the cleaning rotator, if the belt-shaped conveyance body is forcibly moved by the auxiliary drive member in addition to the cleaning rotator, The belt feeding performance can effectively cancel out the expansion and contraction of the belt-like carrier.
Furthermore, in the present invention, if the change in expansion and contraction of the belt-like transport body due to environmental fluctuations is grasped and the auxiliary transport force (rotation driving force or electrostatic attraction force) by the cleaning rotating body is controlled based on this, the environment The auxiliary conveying force by the cleaning rotator can be set optimally in response to the fluctuation, and the expansion and contraction of the belt-like conveying body can be surely offset while considering environmental fluctuations.
Further, according to the cleaning apparatus of the present invention, an image forming apparatus having a good cleaning performance can be easily constructed with respect to the image forming apparatus using the belt-shaped conveyance body.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 shows Embodiment 1 of an image forming apparatus to which the present invention is applied.
In FIG. 1, the image forming apparatus includes a photosensitive drum 10 and an intermediate transfer belt 20 that is in contact with the photosensitive drum 10 to transfer a toner image.
In the present embodiment, the photosensitive drum 10 includes a photosensitive layer whose resistance value is reduced by light irradiation, and a charging device 11 that charges the photosensitive drum 10 is provided around the photosensitive drum 10. An exposure device 12 that writes an electrostatic latent image of each color component (in this example, yellow, magenta, cyan, and black) on the charged photosensitive drum 10, and each color component latent image formed on the photosensitive drum 10. Are provided with a rotary developing device 13 that visualizes the toner with each color component toner, and a photosensitive member cleaning device 14 that cleans the residual toner on the intermediate transfer belt 20 and the photosensitive drum 10.

In the present embodiment, for example, a charging roll is used as the charging device 11, but a charger such as a corotron may be used.
The exposure device 12 may be any device that can write an image on the photosensitive drum 10 with light. For example, a print head using an LED is used, but the present invention is not limited to this, and a print head using an EL. Alternatively, a scanner that scans a laser beam with a polygon mirror may be selected as appropriate.
Further, the rotary type developing device 13 is rotatably mounted with developing units 13a to 13d containing respective color component toners. For example, each color component toner is applied to a portion of the photosensitive drum 10 where the potential is reduced by exposure. There is no particular limitation on the toner to be used as long as it adheres, and the toner to be used is not particularly limited in shape and particle size, and any toner may be used as long as it is accurately placed on the electrostatic latent image on the photosensitive drum 10.
In this embodiment, the rotary developing device 13 is used, but four developing devices may be used.
The photosensitive member cleaning device 14 may be appropriately selected as long as it cleans the residual toner on the photosensitive drum 10 using a blade cleaning method.
However, when using a toner with a high transfer rate, there may be a mode in which the photoconductor cleaning device 14 is not used. At this time, in the case where the residual toner on the intermediate transfer belt 20 is collected by the photosensitive drum 10, for example, a developing device capable of collecting the developer is required.

Further, as shown in FIG. 2, the intermediate transfer belt 20 is stretched between six tension rolls 21 to 26, and is a photosensitive drum positioned between the rotary developing device 13 and the photosensitive member cleaning device 14. Only a predetermined contact area is disposed in close contact with the 10th surface.
Here, the intermediate transfer belt 20 and the photosensitive drum 10 may be driven by separate drive systems, but in the present embodiment, the intermediate transfer belt 20 is an elastic belt as described later, The intermediate transfer belt 20 is driven and rotated by using, for example, the photosensitive drum 10 as a driving source because it is disposed in contact with the circumferential surface of the photosensitive drum 10. Therefore, in this embodiment, each of the stretching rolls 21 to 26 functions as a driven roll, but the stretching roll 23 also serves as an opposing roll (backup roll) for secondary transfer, The tension rolls 24 and 25 also serve as opposed rolls of the cleaning device 40.

In this embodiment, a primary transfer roll 15 as a primary transfer member is disposed in contact with a part of the contact area where the intermediate transfer belt 20 is in close contact with the photosensitive drum 10 from the back side of the intermediate transfer belt 20. A predetermined primary transfer bias is applied.
Further, a secondary transfer roll 30 as a secondary transfer member is disposed opposite to the tension roll 23 of the intermediate transfer belt 20 with the tension roll 23 as a backup roll. For example, the secondary transfer roll A predetermined secondary transfer bias is applied to 30.
Furthermore, a cleaning device (belt cleaner) 40 is disposed between the tension roll 23 and the tension roll 26.
A recording material 50 such as paper is accommodated in a supply tray (not shown), and after being supplied by a pickup roll 51, the recording material 50 is guided to a secondary transfer portion through a transport roll 52 and a resist roll 53, and is then fixed to the fixing device. It is conveyed to 54.

In the present embodiment, the intermediate transfer belt 20 has a fluororesin layer (release layer) laminated on the surface of the elastic rubber substrate (elastic layer) in consideration of, for example, cleanliness when dirt adheres to the surface. A multilayer structure is preferred.
In this case, the elastic rubber substrate (elastic layer) needs a volume resistance (for example, 10 ⁴ Ω or more and 10 ¹⁰ Ω or less) necessary for maintaining transferability.
The elastic rubber substrate (elastic layer) in the present embodiment has a Young's modulus of 30 MPa or less.

In the present embodiment, as shown in FIG. 3, the cleaning device 40 includes a cleaning blade 41 that comes into contact with and separates from the intermediate transfer belt 20, and the moving direction of the intermediate transfer belt 20 from the cleaning blade 41. On the downstream side, there are provided a cleaning brush 42 that contacts the intermediate transfer belt 20 detachably and rotates in the same direction as the movement direction of the intermediate transfer belt 20, and a drive motor 43 that drives the cleaning brush 42. .
Furthermore, in the present embodiment, the cleaning device 40 includes a blade facing roll 44 that contacts the intermediate transfer belt 20 on the back surface side of the intermediate transfer belt 20 and the intermediate transfer belt 20 on the back side of the intermediate transfer belt 20 and the cleaning blade 41. A brush facing roll 45 that comes into contact with the intermediate transfer belt 20 is provided on the back surface side of the intermediate transfer belt 20 at the facing portion between the transfer belt 20 and the cleaning brush 42. In this example, the opposing rolls 44 and 45 also serve as the stretching rolls 24 and 25.

In the present embodiment, the cleaning blade 41 is connected to a bias power source 46 for applying a blade bias. The blade bias may be selected as appropriate, such as only a DC component, only an AC component, or one containing both components.
Here, the cleaning blade 41 is made of, for example, urethane rubber that extends in the width direction of the intermediate transfer belt 20 and has elasticity, and its free end side is disposed in contact with the surface of the intermediate transfer belt 20 and the other end side is illustrated. It is attached to an outer blade holder, and the blade holder is movable so that it can be brought into contact with and separated from the surface of the intermediate transfer belt 20.

The cleaning brush 42 is connected to a bias power supply 47 for applying a brush bias. As the brush bias, only a DC component, only an AC component, or one containing both components may be selected as appropriate.
Here, the cleaning brush 42 is, for example, an embodiment in which the conductive brush base 422 is wound around the conductive shaft 421, but is not limited thereto, and a conductive elastic layer is provided on the conductive support. You may select the roll-shaped thing etc. which were given suitably.

Next, the operation of the image forming apparatus according to the present embodiment will be described focusing on the cleaning device (see FIGS. 2 and 3).
In the image forming apparatus according to the present embodiment, the respective color component toners are sequentially formed on the photosensitive drum 10 and sequentially transferred onto the intermediate transfer belt 20 at the primary transfer position, and then onto the recording material 50 at the secondary transfer position. Batch transfer.
Thereafter, the cleaning blade 41 and the cleaning brush 42 of the cleaning device 40 separated from the intermediate transfer belt 20 are brought into pressure contact with the intermediate transfer belt 20, and the residual toner T on the intermediate transfer belt 20 is cleaned.

At this time, in the case of continuous color printing, the cleaning blade 41 and the cleaning brush 42 are in pressure contact with the intermediate transfer belt 20 only during the image formation of the first color (for example, yellow) after the second sheet.
That is, since the cleaning blade 41 is in pressure contact with the intermediate transfer belt 20, the intermediate transfer belt 20 extends from the blade facing roll 44 on the downstream side in the belt movement direction. In this state, the toner image (for example, yellow) on the photosensitive drum 10 is primarily transferred onto the stretched intermediate transfer belt 20, while the toner blades of other colors are separated from the intermediate transfer belt 20 by the cleaning blade 41. In this state (primary intermediate transfer belt 20 length), the primary transfer is performed on the intermediate transfer belt 20, and thus color misregistration occurs.
Therefore, while the cleaning blade 41 is in pressure contact with the intermediate transfer belt 20, the cleaning brush 42 is driven and rotated in the same direction as the belt moving direction to improve the belt feeding performance, and from the brush facing roll 45 to the photosensitive drum 10. The intermediate transfer belt 20 is shortened to a regular length.
As a result, the first color toner image (for example, yellow) is primarily transferred within the normal length of the intermediate transfer belt 20, and color misregistration with other color toner images does not occur.

Furthermore, in this embodiment, since the intermediate transfer belt 20 is driven and rotated by driving the photosensitive drum 10, the drive control cost of the intermediate transfer belt 20 can be greatly reduced.
Furthermore, since the contact width of the intermediate transfer belt 20 to the photosensitive drum 10 in the primary transfer can be set to be very wide, for example, 50 mm or more, stable follow-up to the intermediate transfer belt 20 can be realized, and transfer Since there is no useless gap before and after the nip area, primary transfer is performed in a state where there is no scattering of toner due to discharge.
Further, from the viewpoint of color superposition, since the drive transmission of the intermediate transfer belt 20 is on the surface of the photosensitive drum 10, it is not affected by unevenness of the belt thickness.
In particular, in the present embodiment, since a wide transfer nip area between the photosensitive drum 10 and the intermediate transfer belt 20 is ensured, it is possible to reduce the pressure in the transfer nip area. The situation where the body drum 10 and the intermediate transfer belt 20 are completely in close contact with each other is more reliably avoided.
In the present embodiment, the photosensitive drum 10 and the intermediate transfer belt 20 are placed in contact with each other in an overlapping state, and the intermediate transfer belt 20 is driven based on the driving force from the photosensitive drum 10. However, the present invention is not limited to this. The photosensitive drum 10 and the intermediate transfer belt 20 have separate drive systems, and the intermediate transfer belt 20 is linearly connected to the photosensitive drum 10. Of course, the present invention can also be applied to an embodiment in which contact is made.

Embodiment 2
Next, a second embodiment of the image forming apparatus according to the present embodiment will be described.
The basic configuration of the image forming apparatus according to the present embodiment is substantially the same as that of the first embodiment, but the configurations of the cleaning brush 42 and the brush facing roll 45 are different from those of the first embodiment.
Components similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted here.

4A to 4C are configuration diagrams of the cleaning brush 60 and the brush facing roll 70 according to the present embodiment.
In the figure, the cleaning brush 60 is a mode in which a gear 61 is provided at one end or both ends in the axial direction of the cleaning brush 42 used in the first embodiment, and the brush facing roll 70 is a first embodiment. It is the aspect which provided the gear 71 in the axial direction one end part or both-sides edge part of the brush opposing roll 45 used by 1.
In the present embodiment, the pitch circle diameters of the gear 61 and the gear 71 are equal, and the gears 61 and 71 are set to have substantially the same shape.
Further, the gear 61 is designed so that the conductive brush base 422 rubs against the intermediate transfer belt 20 when the gears 61 and 71 are engaged with each other, while the gear 71 is the brush facing roll 45. It is sufficient that the surface 45a is designed to come into contact with the intermediate transfer belt 20, and other configurations may be appropriately selected.

Next, the operation of the image forming apparatus according to the present embodiment will be described focusing on the cleaning device (see FIGS. 3 and 4).
The cleaning brush 60 that has been separated from the intermediate transfer belt 20 is pressed against the intermediate transfer belt 20 during cleaning, and is driven to rotate in the same direction as the movement direction of the intermediate transfer belt 20. Thereby, the intermediate transfer belt 20 stretched by the pressure of the cleaning blade 41 is contracted.
At this time, in order to improve the cleaning performance, when the pressure of the cleaning blade 41 is increased, it is necessary to increase the rotation (belt feeding performance) of the cleaning brush 60. However, if the rotation of the cleaning brush 60 is excessively increased, problems such as wear on the surface of the intermediate transfer belt 20 occur.

Accordingly, the brush facing roll 70 facing the cleaning brush 60 is driven, and the extension of the intermediate transfer belt 20 is efficiently performed by the rotation of the cleaning brush 60 (belt feeding performance) and the rotation of the brush facing roll 70 (belt feeding performance). Can be countered.
In this embodiment, since the cleaning brush 60 is provided with a gear 61 and the brush facing roll 70 is provided with a gear 71, the gear 61 of the cleaning brush 60 and the gear 71 of the brush facing roll 70 mesh with each other, whereby the cleaning brush 60 The driving force of 60 can be transmitted to the brush facing roll 70 and can be driven simultaneously.
Accordingly, it is not necessary to provide a driving source for the brush facing roll 70, there is no deviation between the driving timing of the cleaning brush 60 and the driving timing of the brush facing roll 70, and no adverse effects such as color misregistration occur. The elongation of the transfer belt 20 can be canceled out.

Embodiment 3
FIG. 5 shows an essential part of Embodiment 3 of the image forming apparatus to which the present invention is applied.
In the figure, the basic configuration of the image forming apparatus according to the present embodiment is substantially the same as that of the first embodiment. However, unlike the first embodiment, the cleaning brush 42 is rotated depending on the temperature conditions in the image forming apparatus. It is intended to be controlled.
Of the components of the image forming apparatus according to the present embodiment, the same components as those of the image forming apparatus according to the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed descriptions thereof are given here. Description is omitted.

The image forming apparatus according to the present embodiment includes a temperature sensor 80 that detects the temperature in the image forming apparatus, and a control device 90 that controls the rotation state of the cleaning brush 42 based on the detection result by the temperature sensor 80. And a drive motor 43 that changes the rotational speed of the cleaning brush 42 based on a control signal from the control device 90.
Here, a block diagram of the control device 90 is shown in FIG.
5, a temperature detection signal 81 from the temperature sensor 80 shown in FIG. 5 is taken into the CPU 92 via the input interface 91. Next, the CPU 92 executes a drive control program stored in advance in the ROM 93 to execute the RAM 94. After appropriate data processing is performed between the two and the drive source rotation speed control signal (control signal) 96 is transmitted via the output interface 95.

Next, the operation of the image forming apparatus according to the present embodiment will be described focusing on the control device 90.
As shown in FIG. 5, the temperature sensor 80 detects the temperature inside the image forming apparatus. Then, the control device 90 that has received the temperature detection signal 81 (see FIG. 6), as shown in FIG. 7, any range in which the detected temperature is, for example, X ° C. or lower, X ° C. or higher, Y ° C. or lower, or Y ° C. or higher. Are determined, the respective rotation speeds (A to C) are determined, and the drive source rotation speed control signal 96 is sent to the drive motor 43.
As a result, the cleaning brush 42 can change the rotation speed due to a temperature change in the image forming apparatus, and can cope with the expansion and contraction of the intermediate transfer belt 20 due to the temperature change.

Embodiment 4
As shown in FIG. 8, the basic configuration of the image forming apparatus according to the present embodiment is substantially the same as that of the third embodiment. However, unlike the third embodiment, the reflection sensor 85 cleans the intermediate transfer belt 20. The peripheral speed of the intermediate transfer belt 20 is detected when the blade 41 and the cleaning brush 42 (the cleaning device 40 in the present embodiment) are pressed against and separated from each other, and the control device 90 rotates the cleaning brush 42 based on the detection result. Is controlled.
Of the components of the image forming apparatus according to the present embodiment, the same components as those of the image forming apparatus according to the third embodiment are denoted by the same reference numerals as those in the third embodiment, and the detailed description thereof is here. Description is omitted.

In the image forming apparatus according to the present embodiment, as shown in FIG. 8, a reflective seal 86 is provided outside the image forming area range on the intermediate transfer belt 20, and the reflective sensor 85 detects the reflective seal 86. is there.
In other words, as shown in FIG. 6, the control device 90 in the present embodiment takes in the reflection detection signal 87 from the reflection sensor 85 instead of the temperature detection signal 81, and the cleaning brush 42 by this reflection detection signal 87. The number of rotations is controlled.

Next, the operation of the image forming apparatus according to the present embodiment will be described focusing on the control device 90 (see FIGS. 6, 8, and 9).
While the cleaning blade 41 and the cleaning brush 42 are separated from the intermediate transfer belt 20, the rotation speed of the intermediate transfer belt 20 (time t 1 between the reflection seals 86) is detected by the reflection sensor 85, while the cleaning blade 41. In the state where the cleaning brush 42 is in pressure contact with the intermediate transfer belt 20, the speed of one rotation of the intermediate transfer belt 20 (time t <b> 2 between the reflection seals 86) is detected by the reflection sensor 85.
Then, based on the reflection detection signal 87, the control device 90 determines, for example, which range of W to Xmsec, X to Ymsec, and Y to Zmsec from the time difference (t2−t1), and then the respective rotation speeds. (A to C) is determined, and a drive source rotational speed control signal 96 is sent to the drive motor 43.
Therefore, according to the present embodiment, the cleaning brush 42 changes the rotation speed even when the material of the intermediate transfer belt 20 is softened and the degree of expansion / contraction changes due to environmental fluctuations such as temperature and humidity. It is possible to cope with environmental fluctuations in the image forming apparatus.

Embodiment 5
FIG. 10 shows a main part of a fifth embodiment of the image forming apparatus to which the present invention is applied.
In this figure, the basic configuration of the image forming apparatus according to the present embodiment is substantially the same as that of the third embodiment, but unlike the third embodiment, the intermediate transfer belt 20 overlaps the photosensitive drum 10. In addition, the photosensitive drum 10 and the intermediate transfer belt 20 are driven by separate drive systems, respectively, and the cleaning device 40 for the intermediate transfer belt 20 is a cleaning brush. A metal cleaning scraper 41 is used on the upstream side of 42 instead of the cleaning blade.
In particular, unlike the third embodiment, the present embodiment is characterized in that the bias (applied voltage) applied to the cleaning brush 42 is controlled according to the temperature conditions in the image forming apparatus.
In the present embodiment, the cleaning brush 42 is desirably a brush raw yarn having a small mechanical force and a Young's modulus of 2500 cN / mm ² or less, and effectively uses an electrostatic force (electrostatic adsorption force). In order to use it, it is desirable that the raw yarn resistance of the brush is 10 ⁴ Ω · cm or more and 10 ¹⁰ Ω · cm or less.
Of the components of the image forming apparatus according to the present embodiment, the same components as those of the image forming apparatus according to the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed descriptions thereof are given here. Description is omitted.

The image forming apparatus according to the present embodiment includes a temperature sensor 80 that detects the temperature in the image forming apparatus, and a control device 90 that controls the voltage applied to the cleaning brush 42 based on the detection result by the temperature sensor 80 (FIG. 6) and a bias power source 47 that changes the voltage applied to the cleaning brush 42 based on a control signal from the control device 90.
Here, for example, as shown in FIG. 6, the temperature detection signal 81 from the temperature sensor 80 is taken into the CPU 92 via the input interface 91, and then the CPU 92 executes a drive control program stored in advance in the ROM 93. Then, after appropriately performing data processing with the RAM 94, a power control signal 97 is transmitted via the output interface 95.

Next, the operation of the image forming apparatus according to the present embodiment will be described focusing on the control device 90.
As shown in FIG. 10, the temperature sensor 80 detects the temperature in the image forming apparatus. Upon receiving the temperature detection signal 81 (see FIG. 6) from the temperature sensor 80, the control device 90, as shown in FIG. 11, the detected temperature is, for example, X ° C. or less, X ° C. or more, Y ° C. or less, Y ° C. It is determined which range is above, thereby determining an applied voltage value (α to γ) to the cleaning brush 42, and sending a power supply control signal 97 to the bias power supply 47.
As a result, the applied voltage of the cleaning brush 42 can be changed by a temperature change in the image forming apparatus, and the electrostatic field between the cleaning brush 42 and the intermediate transfer belt 20 changes accordingly. Thus, a predetermined electrostatic attraction force by the cleaning brush 42 acts on the intermediate transfer belt 20 and gives an auxiliary conveying force to the intermediate transfer belt 20. This auxiliary conveying force can cope with expansion and contraction of the intermediate transfer belt 20 due to temperature change.
In this embodiment, the voltage applied to the cleaning brush 42 is controlled. However, the present invention is not limited to this, and the voltage applied to the cleaning scraper 41 may also be controlled. . In this case, as shown in FIG. 11, for example, voltage values (α ′ to γ ′) applied to the cleaning scraper 41 are determined according to the temperature condition, and the power control signal 98 is sent to the bias power source 46. do it.

Embodiment 6
As shown in FIG. 12, the basic configuration of the image forming apparatus according to the present embodiment is substantially the same as that of the fifth embodiment. However, unlike the fifth embodiment, the reflection sensor 85 cleans the intermediate transfer belt 20. The peripheral speed of the intermediate transfer belt 20 is detected when the scraper 41 and the cleaning brush 42 (the cleaning device 40 in this embodiment) are pressed and separated from each other, and the control device 90 applies the cleaning brush 42 to the cleaning brush 42 based on the detection result. The applied voltage is controlled.
Note that among the components of the image forming apparatus according to the present embodiment, the same components as those of the image forming apparatus according to the fifth embodiment are denoted by the same reference numerals as those in the fifth embodiment, and the detailed description thereof is here. Description is omitted.

In the image forming apparatus according to the present embodiment, as shown in FIG. 12, a reflective seal 86 is provided outside the image forming area range on the intermediate transfer belt 20, and the reflective sensor 85 detects the reflective seal 86. is there.
In other words, as shown in FIG. 6, the control device 90 in the present embodiment takes in the reflection detection signal 87 from the reflection sensor 85 instead of the temperature detection signal 81, and the cleaning brush 42 by this reflection detection signal 87. The voltage applied to is controlled.

Next, the operation of the image forming apparatus according to the present embodiment will be described focusing on the control device 90 (see FIGS. 6, 12, and 13).
In a state where the cleaning scraper 41 and the cleaning brush 42 are separated from the intermediate transfer belt 20, the rotation speed of the intermediate transfer belt 20 (time t <b> 1 between the reflection seals 86) is detected by the reflection sensor 85, while the cleaning scraper 41. In the state where the cleaning brush 42 is in pressure contact with the intermediate transfer belt 20, the speed of one rotation of the intermediate transfer belt 20 (time t <b> 2 between the reflection seals 86) is detected by the reflection sensor 85.
Based on the reflection detection signal 87, the control device 90 determines, for example, which range of W to Xmsec, X to Ymsec, and Y to Zmsec, based on the time difference (t2−t1), and thereby the cleaning brush. 42 determines an applied voltage value (α to γ) to 42 and sends a power supply control signal 97 to the bias power supply 47.

As a result, the applied voltage of the cleaning brush 42 can be changed even when the material of the intermediate transfer belt 20 is softly cured and the degree of expansion / contraction changes due to environmental fluctuations such as temperature and humidity. Along with this, the electrostatic field between the cleaning brush 42 and the intermediate transfer belt 20 changes, and the electrostatic adsorption force by the cleaning brush 42 acts on the intermediate transfer belt 20 to give an auxiliary conveying force to the intermediate transfer belt 20. . This auxiliary conveying force can cope with expansion and contraction of the intermediate transfer belt 20 due to temperature change.
In this embodiment, the voltage applied to the cleaning brush 42 is controlled. However, the present invention is not limited to this, and the voltage applied to the cleaning scraper 41 may also be controlled. . In this case, for example, as shown in FIG. 13, the voltage values (α ′ to γ ′) applied to the cleaning scraper 41 are determined according to the temperature conditions, and the power supply control signal 98 is sent to the bias power supply 46. do it.

In the fifth and sixth embodiments, the voltage applied to the cleaning brush 42 and the like is controlled. However, the present invention is not limited to this, and the electrostatic field between the cleaning brush 42 and the intermediate transfer belt 20 is not limited thereto. As long as the electrostatic attraction force between them can be controlled, the design can be changed as appropriate, for example, by controlling the supply current of the bias power supply 47 and the like.
Further, in the fifth and sixth embodiments, an electrostatic force is controlled as an auxiliary conveying force applied to the intermediate transfer belt 20. For example, the cleaning brush 42 is combined with any one of the first to fourth embodiments. Of course, a mechanical force may also be controlled as the auxiliary conveying force, such as controlling the number of rotations.

◎ Embodiment 7
FIG. 14 shows Embodiment 7 of an image forming apparatus to which the present invention is applied.
In this figure, the basic configuration of the image forming apparatus according to the present embodiment is substantially the same as the image forming apparatus model shown in the fifth embodiment, but the residual toner T ′ cleaned by the cleaning brush 42 (FIG. 14). (Shown by a dotted line) is discharged and collected by the photoconductor cleaning device 14 on the photoconductor drum 10 side.
In the present embodiment, as shown in FIG. 14, the bias power supply 47 for the cleaning brush 42 includes a cleaning power supply 471 for applying a residual toner charging polarity and a different polarity voltage to the cleaning brush 42, and a residual toner charging polarity. And a changeover switch 473 for switching between the cleaning power supply 471 and the toner discharge power supply 472.
Of the components of the image forming apparatus according to the present embodiment, the same components as those of the image forming apparatus according to the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed descriptions thereof are given here. Description is omitted.

Next, the operation of the image forming apparatus according to the present embodiment will be described focusing on the cleaning device 40.
In the present embodiment, as shown in FIG. 14, the cleaning process on the intermediate transfer belt 20 is substantially the same as in the fifth embodiment. In this case, the changeover switch 473 is connected to the cleaning power supply 471, and the cleaning brush 42 removes residual toner on the intermediate transfer belt 20.
Here, when the residual toner adhering to the cleaning brush 42 is collected by the photosensitive drum 10, the changeover switch 473 is switched to the toner discharge power source 472, and the intermediate transfer belt 20 is charged with the charging polarity of the residual toner from the primary transfer roll 15. The same polarity voltage is applied.
As a result, the residual toner adhering to the cleaning brush 42 is discharged onto the intermediate transfer belt 20 by the electrostatic repulsive force acting between the cleaning brush 42 and the residual toner, and moves on the intermediate transfer belt 20.
The moved residual toner T ′ (indicated by a dotted line in FIG. 14) moves on the photosensitive drum 10 by the voltage applied to the primary transfer roll 15, and the residual toner moved on the photosensitive drum 10 is photosensitive. Cleaning is performed by a photoconductor cleaning device 14 installed on the body drum 10.

When the collection of the residual toner attached to the cleaning brush 42 is completed as described above, the cleaning scraper 41 and the cleaning brush 42 are separated from the intermediate transfer belt 20, and the changeover switch 473 is switched to the cleaning power supply 471 to enter a standby state. .
In addition, as soon as the cleaning scraper 41 and the cleaning brush 42 start to be separated from the intermediate transfer belt 20, the voltage application to the primary transfer roll 15 is also stopped.
Although this embodiment is applied to the image forming apparatus model of the fifth embodiment, it is needless to say that the present embodiment can be applied to other embodiment models.

In this example, using the image forming apparatus according to the first embodiment (see FIGS. 2 and 3), the three types of cleaning brushes 42 having different lengths and hardnesses are used, and the intermediate transfer belt 20, the cleaning brush 42, and the like. The color registration misalignment (elongation of the intermediate transfer belt 20) when the peripheral speed difference ratio is changed is measured.
When the peripheral speed of the intermediate transfer belt 20 and the peripheral speed of the cleaning brush 42 are the same, the electrostatic transfer force acting between the intermediate transfer belt 20 and the cleaning brush 42 attracts each other. Since the belt feeding performance cannot be exerted on the belt 20, the load on the cleaning blade 41 cannot be canceled. As a result, the intermediate transfer belt 20 is stretched and color registration shift occurs.
Therefore, in order to cancel the load of the cleaning blade 41 on the intermediate transfer belt 20 by the rotation of the cleaning brush 42, it is necessary to make the peripheral speed of the cleaning brush 42 faster than the peripheral speed of the intermediate transfer belt 20.

In order to confirm this, when the circumferential speed ratio between the intermediate transfer belt 20 and the cleaning brush 42 was changed using three types (A, B, C) of cleaning brushes 42 having different lengths and hardnesses, Results as shown in FIG. 15 were obtained.
According to the figure, the color registration misalignment characteristics are different depending on the A to C brushes. For example, when the peripheral speed difference ratio is 1.5 times or more with the B brush, the color registration misalignment is an absolute value of about | 0.07 mm | Thus, it was confirmed that the color registration deviation was within an allowable range.
Therefore, it is understood that the peripheral speed difference ratio between the intermediate transfer belt 20 and the cleaning brush 42 is required to be 1.5 times or more.

In this example, the color registration when the bias (applied voltage) applied to the cleaning scraper 41 or the cleaning brush 42 is changed using the image forming apparatus according to the fifth or sixth embodiment (see FIGS. 10 and 12). When the deviation was measured, the results shown in FIGS. 16 and 17 were obtained.
FIG. 16 shows the relationship between the voltage applied to the cleaning brush 42 and the color registration error, and FIG. 17 shows the relationship between the voltage applied to the cleaning scraper 41 and the color registration error.
In the figure, it is understood that the color registration error increases approximately proportionally with respect to the cleaning brush 42 if the applied voltage is increased.
On the other hand, with respect to the cleaning scraper 41, it is understood that if the absolute value of the applied voltage is increased, the color registration deviation increases in proportion thereto.
Therefore, it is possible to change the color registration deviation by adjusting the voltage applied to the cleaning brush 42 or the cleaning scraper 41, and in the expansion / contraction control of the intermediate transfer belt 20, the cleaning member (the cleaning brush 42 or the cleaning scraper 41). It is understood that the applied voltage can be used as a parameter.

1 is an explanatory diagram showing an outline of an image forming apparatus according to the present invention and a cleaning device used therefor. 1 is an explanatory diagram illustrating an image forming apparatus according to Embodiment 1. FIG. FIG. 3 is an explanatory diagram illustrating details of the cleaning device used in the first embodiment. (A) is explanatory drawing which shows the detail of the cleaning brush used in Embodiment 2, and a brush opposing roll, (b) is explanatory drawing which shows A cross section of a brush opposing roll, (c) shows B cross section of a cleaning brush. It is explanatory drawing. FIG. 10 is an explanatory diagram illustrating a main part of an image forming apparatus according to a third embodiment. 6 is a block diagram showing a specific configuration of a control device used in Embodiment 3. FIG. 10 is a flowchart showing an operation of a control device used in the third embodiment. FIG. 10 is an explanatory diagram illustrating a main part of an image forming apparatus according to a fourth embodiment. 10 is a flowchart showing an operation of a control device used in the fourth embodiment. FIG. 10 is an explanatory diagram illustrating an image forming apparatus according to a fifth embodiment. 10 is a flowchart showing an operation of a control device used in the fifth embodiment. FIG. 10 is an explanatory diagram illustrating an image forming apparatus according to a sixth embodiment. 10 is a flowchart showing an operation of a control device used in the sixth embodiment. FIG. 10 is an explanatory diagram illustrating an image forming apparatus according to a seventh embodiment. In Example 1, it is explanatory drawing which shows the measurement result of the color registration shift | offset | difference when changing the peripheral speed difference ratio of an intermediate transfer belt and a cleaning brush. In Example 2, it is explanatory drawing which shows the measurement result of a color registration shift when changing the applied voltage to a cleaning brush. In Example 2, it is explanatory drawing which shows the measurement result of color registration shift | offset | difference when changing the voltage applied to a cleaning scraper.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Stretching roll, 2 ... Belt-shaped conveyance body, 3 ... Cleaning apparatus, 4 ... Cleaning plate-shaped member, 5 ... Cleaning rotary body, 6 ... Expansion-contraction control means, 7 ... Rotating body opposing member, T ... Residue

Claims (10)

A belt-shaped carrier having an elastic layer is stretched in a plurality of tension rolls image or recording material is carried and conveyed together with the driven conveyed by the drive system, and a cleaning device for cleaning the belt-shaped carrier In the provided image forming apparatus,
The cleaning device includes a cleaning plate-like member that extends in a plate shape across a width direction orthogonal to the moving direction of the belt-like conveyance body, and whose tip is in contact with and separated from the belt-like conveyance body;
A cleaning rotating body that contacts and separates from the belt-shaped transport body and rotates in the same direction as the movement direction of the belt-shaped transport body at the time of contact ;
Furthermore, a rotating body facing member disposed in contact with the back surface of the belt-shaped transport body facing the cleaning rotating body with the belt-shaped transport body interposed therebetween,
When the cleaning rotator is brought into pressure contact with the belt-like transport body, a rotational driving force is applied to the cleaning rotator, and a rotating body facing member is assisted along the moving direction of the belt-like transport body with the cleaning rotator as a drive source. Belt is generated when the cleaning plate-like member is brought into contact with or separated from the belt-like carrier by providing an auxiliary conveying force to the belt-like carrier via the cleaning rotator and the rotator-opposing member. An image forming apparatus comprising: an expansion / contraction control unit that cancels out expansion and contraction of the sheet-like conveyance body. The image forming apparatus according to claim 1.
The expansion / contraction control means drives the stretching roll in an auxiliary manner along the moving direction of the belt-like conveyance body when the cleaning rotating body comes into pressure contact with the belt-like conveyance body. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the belt-like conveyance body has a multilayer structure in which a release layer is laminated on at least the surface of an elastic layer. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the elastic layer of the belt-shaped carrier has a Young's modulus of 30 MPa or less. The image forming apparatus according to claim 1.
The expansion and contraction control means detects the expansion and contraction state of the belt-shaped transport body by detecting the peripheral speed of the belt-shaped transport body, and
Control means for controlling the rotation state of the cleaning rotator based on the detection result by the detection means;
An image forming apparatus comprising: drive means for driving the cleaning rotator based on a control signal from the control means. The image forming apparatus according to claim 1.
The expansion / contraction control means includes applying an electrostatic field between the cleaning rotator and the belt-like conveyance body. The image forming apparatus according to claim 1.
The expansion / contraction control means includes applying an electrostatic field between the cleaning plate-like member and the belt-like conveyance body. The image forming apparatus according to claim 6 or 7 ,
The expansion / contraction control means changes an electrostatic field formed between a cleaning member composed of a cleaning rotator or a cleaning plate-like member and a belt-like conveyance body according to the environment. The image forming apparatus according to claim 1.
The expansion / contraction control means includes a detection means for detecting the expansion / contraction state of the belt-shaped carrier,
Control means for controlling the electrostatic field formed between the cleaning member formed of the cleaning rotating body or the cleaning plate-like member and the belt-like conveyance body based on the detection result by the detection means;
An image forming apparatus comprising: a power source that causes the electrostatic field to act based on a control signal from the control means. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the cleaning rotator has a brush shape.

Images