JP3581600B2 - Image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a copier, a printer, and other electrophotographic or electrostatic recording type image forming apparatuses.
[0002]
[Prior art]
Conventionally, various image forming apparatuses have been developed. In an image forming apparatus such as a copying machine or a laser beam printer, a toner image is formed on the surface of a photosensitive drum serving as an image carrier, and the toner image is formed on paper or the like. In the case of the method of transferring to a transfer material, the residual toner remaining on the surface of the photosensitive drum after the transfer of the toner image is removed by a cleaning device.
[0003]
On the other hand, in a color copying machine, even in a model provided with an intermediate transfer member in order to enhance the selectivity of a transfer material, untransferred toner remaining on the intermediate transfer member is removed by a cleaning device for the intermediate transfer member.
[0004]
The cleaning device as described above has, for example, a cleaning blade in which an elastic member such as urethane rubber is formed in a plate shape, and the edge of the cleaning blade is brought into contact with the surface of the photosensitive drum at a predetermined pressure, thereby forming a photosensitive drum. The residual toner adhering to the surface is scraped off.
[0005]
A cleaning device using the cleaning blade has a relatively simple structure and a small size, is advantageous in terms of cost, and has an advantage of excellent toner removal performance, and is therefore widely used.
[0006]
In particular, in a high-quality color image forming apparatus that requires high-speed and high-quality images, in order to minimize vibration and damage to the transfer member, a simpler light-pressure type brush cleaner or cleaning less than a cleaning blade is used. Some models have introduced types.
[0007]
[Problems to be solved by the invention]
However, in the above-described image forming apparatus, since the cleaning blade is in contact with the surface of the photosensitive drum, the residual toner is firmly adhered to the cleaning blade as the image forming apparatus is used for a long time, and so-called filming occurs. There is a problem that the image quality may be deteriorated thereafter.
[0008]
In recent years, an image forming apparatus forms an image on a front surface (first surface) of a transfer material, and then reverses the transfer material in the image forming apparatus and re-inverts the transfer material on a rear surface (second surface). Those having a so-called double-sided image forming function for forming an image are often used.
[0009]
In such an image forming apparatus, when a general fixing device having a configuration in which a transfer material is passed through a nip portion of a pair of rollers for fixing a toner image is used, a roller is used to prevent toner from adhering to the roller. Apply silicone oil to the surface.
[0010]
This silicone oil adheres to the transfer device when the toner image on the second surface is transferred, and adheres to the intermediate transfer body when the image of the next page is formed.
[0011]
The silicon oil adhering to the surface of the intermediate transfer member is partially transferred to and adheres to the photosensitive drum in contact with the intermediate transfer member, resulting in poor image quality due to oil contamination of the intermediate transfer member and defective charging due to oil contamination on the surface of the photosensitive drum. Also, there is a problem that the cleaning failure may occur by mixing with the toner present at the edge of the cleaning blade and slipping through the edge of the cleaning blade.
[0012]
Further, in order to achieve high image quality, it is necessary to prevent the transfer member from being damaged by the cleaning member as much as possible by using the structure including the transfer member. The setting of the cleaning mechanism includes light pressure, simplification, and A cleaner-less system on the assumption that a toner having a high transfer efficiency is used is being put to practical use.
[0013]
In this case, the ability to remove charged products remaining on the intermediate transfer member, transfer oil, paper dust, dust, and the like tends to be reduced.
[0014]
Also, if the contact pressure of the member for cleaning the toner on the intermediate transfer member is forcibly increased, the damage to the intermediate transfer member is increased, and defects in image formation such as poor conveyance of the intermediate transfer member are likely to be remarkable. is there.
[0015]
In addition, the retention of the electrical memory due to charging is a factor that hinders image defects and long-term stabilization of image quality, and has the disadvantage that residual toner having charge on the intermediate transfer member is difficult to clean.
[0016]
Further, in a model using an intermediate transfer member, there is a problem that image quality is degraded by performing the transfer twice. Therefore, in order to enhance the transferability of the toner to the intermediate transfer member as much as possible, the image carrier and the intermediate member are used. In general, the transfer member is in a form of being in constant contact.
[0017]
For example, the contact pressure of a contact member such as a static elimination member for removing residual charges on the intermediate transfer member or a cleaning member for removing residual toner is minimized to vibrate the intermediate transfer member and the image carrier. It is indispensable to not give the image, during the image formation, by changing the rotation speed of the static elimination member, to increase the relative speed difference with the image carrier, and to improve the abrasiveness of the intermediate transfer member surface, It is considered to be a factor that hinders high-quality image formation, and it has become difficult to achieve both high-quality image formation and cleaning of the intermediate transfer member.
[0018]
Therefore, in the conventional image forming apparatus, it is possible to prevent the occurrence of filming due to long-term use and the prevention of cleaning failure due to the adhesion of silicone oil at the time of fixing without complicating the structure, and the cleaning in the simple intermediate transfer body cleaning apparatus. It has been difficult to simultaneously secure the transferability and the charge elimination of the transfer member, and to prevent the deterioration of the image quality.
[0019]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus capable of preventing a deterioration in image quality while securing a cleaning property and a transfer body static elimination property while avoiding a complicated structure. With the goal.
[0020]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus according to the present invention has an image carrier having a movable surface on which a latent image is formed, and a toner image formed on the image carrier is transferred to a sheet material. An image forming apparatus including an intermediate transfer member for performing charge removal, and a charge removing unit configured to contact the intermediate transfer member to remove charge from the intermediate transfer member. Stop driving the static elimination means It is characterized in that a relative speed difference is provided between the driving speeds of the contact portions of the intermediate transfer body and the charge removing means, and the relative speed difference is not provided during image formation.
[0021]
Further, when there is a relative speed difference between the drive speed of the intermediate transfer body and the drive speed of the charge removing unit, at least one of the drive speeds of the intermediate transfer body and the charge removing unit is the image carrier. The driving speed is higher than the respective driving speed when the toner image formed on the sheet material is transferred onto the sheet material.
[0022]
Further, the intermediate transfer member and the charge eliminating means have a relative speed difference between a driving speed of the intermediate transfer member and a driving speed of the charge eliminating member at a predetermined time interval.
[0023]
The driving of the intermediate transfer member is stopped when there is a relative speed difference between the driving speed of the intermediate transfer member and the driving speed of the charge removing means.
[0024]
Further, the drive speed of the charge eliminator when there is a relative speed difference between the drive speed of the intermediate transfer body and the drive speed of the charge eliminator, causes the toner image formed on the image bearing member to move. It is characterized in that the speed is higher than the driving speed of the charge removing means when transferring to a sheet material.
[0025]
Further, when there is a relative speed difference between the drive speed of the intermediate transfer member and the drive speed of the charge eliminating means, the drive of the charge eliminating means is stopped.
[0026]
Further, the driving speed of the intermediate transfer member when there is a relative speed difference between the driving speed of the intermediate transfer member and the driving speed of the charge elimination means, the toner image formed on the image carrier is changed. The transfer speed is higher than the drive speed of the intermediate transfer body when transferring to the sheet material.
[0027]
The image forming apparatus further includes a detecting unit configured to detect at least one of a temperature and a humidity of the image forming apparatus main body, and a driving speed of at least one of the intermediate transfer body and the static elimination unit based on a detection result by the detecting unit. Is changed.
[0028]
Further, a driving time of at least one of the intermediate transfer member and the charge removing unit is changed based on a detection result by the detecting unit.
[0029]
The image forming apparatus further includes a detecting unit configured to detect at least one of a temperature and a humidity of the image forming apparatus main body, and based on a detection result of the detecting unit, a driving time of at least one of the intermediate transfer body and the charge removing unit. Is changed.
[0030]
Further, when there is a relative speed difference between the drive speed of the intermediate transfer body and the drive speed of the charge removing unit, the time when the latent image is formed on the image carrier and the time when the sheet material is It is characterized by being at a time other than when the toner image is transferred.
[0031]
Therefore, according to the image forming apparatus of the present invention, for example, during a non-image forming operation, the intermediate transfer body and the charge removing unit are driven with a relative speed difference, so that the image forming operation is not affected. Because of the friction between the intermediate transfer member and the charge removing means, the mating members are polished with each other, and the dust and the like remaining on the intermediate transfer member and the charge removing means can be effectively removed. In addition, image formation can be performed with high stability.
[0032]
Further, when the intermediate transfer member and the discharging unit are driven with a relative speed difference, at least one of the driving speeds of the intermediate transfer member and the discharging unit is such that the toner image formed on the image carrier is a sheet. Since the driving speed is higher than the driving speed at the time of transferring to the material, the polishing property and the cleaning property can be further improved.
[0033]
Further, since the intermediate transfer body and the charge removing means are driven at predetermined time intervals with a relative speed difference, they are not always driven with a relative speed difference. Can be lightened, and the life can be extended.
[0034]
Further, when the intermediate transfer body and the charge removing means are driven with a relative speed difference, the drive of the intermediate transfer body is stopped, so that the relative speed difference between the intermediate transfer body and the charge removing means increases, and The polishing property and the cleaning property can be improved.
[0035]
Further, when the drive of the intermediate transfer member is stopped, since the drive speed of the charge removing unit is higher than the drive speed of transferring the toner image formed on the image carrier to the sheet material, Further, the polishing property and the cleaning property can be improved.
[0036]
In addition, when the intermediate transfer member and the neutralizing unit are driven with a relative speed difference, the driving of the neutralizing unit is stopped, so that the relative speed difference between the intermediate transfer body and the neutralizing unit increases, and further polishing is performed. Properties and cleaning properties can be improved.
[0037]
Further, when the drive of the charge removing unit is stopped, since the drive speed of the intermediate transfer member is higher than the drive speed of transferring the toner image formed on the image carrier to the sheet material, Further, the polishing property and the cleaning property can be improved.
[0038]
Further, since the drive speed of at least one of the intermediate transfer body and the charge removing unit is changed based on the detection result of the detection unit that detects at least one of the temperature and the humidity of the image forming apparatus main body, Since the driving speed is changed according to the environment, the driving operation can be performed as required, and the life of the device can be extended while maintaining the polishing and cleaning properties.
[0039]
Further, since the drive time of at least one of the intermediate transfer member and the charge removing unit is changed based on the detection result of the detection unit that detects at least one of the temperature and the humidity of the image forming apparatus main body, The driving time is changed according to the environment, the driving operation can be performed as required, and the life of the device can be extended while maintaining the polishing and cleaning properties.
[0040]
Also, the time when the intermediate transfer body and the neutralization unit are driven with a relative speed difference is other than when the latent image is formed on the image carrier and when the toner image is transferred to the sheet material. Even if the intermediate transfer member and the neutralization unit rub against each other, the image forming operation is not affected and the image quality can be maintained.
[0041]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto unless otherwise specified. Absent.
[0042]
(1st Embodiment)
First, an image forming apparatus according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a partial configuration diagram of a first embodiment of an image forming apparatus according to the present invention.
[0043]
The image forming apparatus shown in FIG. 1 is a four-color full-color copying machine, and is disposed inside an image forming apparatus main body (hereinafter, referred to as an “apparatus main body”) 100 along a rotational conveyance direction A of a photosensitive drum 1 as an image carrier. Four image forming units are provided in order from the upstream side to the downstream side, that is, a first image forming unit 4a, a second image forming unit 4b, a third image forming unit 4c, and a fourth image forming unit 4d. I have.
[0044]
As shown in FIG. 1, each of the first to fourth image forming units 4a to 4d includes a photosensitive drum 1 which is a drum-type electrophotographic photosensitive member as an image carrier. As the photosensitive drum 1, a photosensitive layer having a carrier generating layer (CGL) and a carrier transporting layer (CTL) is coated on a surface of a cylindrical aluminum base such that the CTL has a thickness of 40 μm, and a JIS surface rough coating. Rz (B0601) having an Rz (10-point average) of 2 μm or less in an initial state was used.
[0045]
The photosensitive drum 1 is rotatably supported by the apparatus main body 100 and is rotationally driven by a driving means (not shown) at a process speed of 120 mm / sec in the direction of arrow A. The photosensitive drum 1 had an outer diameter of 80 mm.
[0046]
Above the photosensitive drum 1, a primary charger 2 is disposed in close proximity, and the surface of the photosensitive drum 1 is uniformly charged by the primary charger 2. The surface of the charged photosensitive drum 1 is exposed to an optical system (toner image forming unit) disposed above the image forming unit to form an electrostatic latent image, and thereafter, is exposed to light by a blank exposing unit 3.
[0047]
Subsequently, the toner in the developer is attached to the electrostatic latent image by the first to fourth image forming units 4a to 4d, and is developed as a toner image. As a developer, a two-component developer mainly composed of a silicon-based toner and a ferrite-based carrier was used.
[0048]
The toner image is applied to the photosensitive drum 1 at a linear pressure of 5 gr / cm (a value obtained by dividing a member pressure applied in the thrust direction by a length in the drum thrust direction). When the intermediate transfer belt 11, which is an intermediate transfer member rotating in the direction, arrives at a transfer site where the intermediate transfer belt 11 comes into contact with the intermediate transfer belt 11, the electric field formed by the intermediate transfer belt 11 charged in advance causes the intermediate transfer belt 11 to move from the surface of the photosensitive drum 1. It is transferred in a form that is electrostatically attracted to.
[0049]
Here, assuming that the contact pressure of the charge removing roller 21 as the charge removing unit with the intermediate transfer belt 11 during image formation is P1 and the contact pressure during non-image formation is P2, P1 = P2> 0 is satisfied. ing. The neutralizing roller 21 is provided with a neutralizing roller-facing ground member 22 at a position facing the neutralizing roller 21.
[0050]
The intermediate transfer belt 11 described above uses EPDM rubber, chloroprene rubber, epichlorohydrin rubber, silicone rubber, NBR rubber, or a modified rubber thereof as a base layer material.
[0051]
As the material of the surface layer, a material containing a fluororesin (for example, a material containing PVDF, PTFE, ethylene tetrafluoride, etc.) is used from the viewpoint of high releasability and low friction coefficient.
[0052]
Here, FIG. 2 is a partially enlarged view of the intermediate transfer belt 11 shown in FIG. In the present embodiment, as shown in FIG. 2, EPDM rubber is used for a base layer 11a constituting the intermediate transfer belt 11, and a coating material in which a PVDM resin is dispersed is coated on the base layer 11a to form a surface layer 11b. .
[0053]
In addition, EPDM rubber was used for the base layer of the charge removing roller 21, and carbon was dispersed and added as a conductive filler to the base layer to form a surface layer that comes into contact with the intermediate transfer belt 11.
[0054]
The surface layer of the roller opposed to the intermediate transfer belt 11 is also made of the same material, and a member is used as a member for grounding the charge by static elimination. Both rollers had an outer diameter of 16 mm and a thrust length of 306, and the contact pressure of the neutralizing member against the intermediate transfer belt 11 was 400 gf.
[0055]
The intermediate transfer belt 11 is conveyed in the direction of arrow B to the primary transfer bias roller 8, the support roller 9, facing the photosensitive drum 1, the opposite roller 10 facing the secondary transfer bias roller 12, and the opposite roller 19 facing the cleaning blade 16. It is hung rotatably.
[0056]
Further, a cleaning blade 16 as a cleaning means for the intermediate transfer belt 11 was brought into contact with the intermediate transfer belt 11 in the forward direction with respect to the transport rotation direction. Incidentally, polyurethane rubber was used as a material of the cleaning blade 16.
[0057]
The residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image without being transferred to the transfer material P is scraped off by the cleaning blade 17 of the cleaning device 5 and further removed by the pre-exposure lamp 15. It is removed and used for the next image formation.
[0058]
The photosensitive drum 1 on which the first toner image has been formed by the first image forming unit 4a as described above is transported and rotated, and the second image forming unit 4b, the third image forming unit 4c, and the fourth image forming unit 4c are rotated. As in the case of the first image forming unit 4a, the toner images are multiple-developed by the image forming unit 4d.
[0059]
However, the toner colors of the toner images developed in the first to fourth image forming units 4 a to 4 d are different from each other, and the four color toner images are collectively transferred onto the intermediate transfer drum 11 by the primary transfer bias roller 8. Then, the transfer material P is conveyed to the secondary transfer bias roller 12 so that the timing is adjusted to the toner composite image on the intermediate transfer belt 11, where the toner composite image is collectively transferred and transferred to the transfer material P. The material P is transported through a transfer material transport path 18 to a fixing unit 14 for fixing the toner image, and is fixed by receiving heat and pressure from the fixing unit 14 to obtain a copy image.
[0060]
At this time, for example, silicone oil is applied as a release agent to the surface of the fixing roller of the fixing unit 14 so that the toner on the transfer material P does not adhere to the surface of the fixing roller.
[0061]
The transfer material P on which the toner image is formed on the front surface (first surface) passes over the flapper and is discharged onto the discharge tray when the image formation is on one side. Accordingly, when the image formation is performed on both sides, the transfer material P having the toner image fixed on the first surface is guided to the lower re-feeding unit without being discharged to the paper discharge tray by switching the flapper.
[0062]
Then, after the image is reversed by the reversing device, the toner image is again transferred to the second surface, is fixed by the fixing unit 14, is discharged above the flapper, and is discharged onto the paper discharge tray to form the image. Is completed.
[0063]
Thereafter, the photosensitive drum 1 performs a three-rotation idle rotation operation (at-rotation), and at the same time, the intermediate transfer belt 11 that is in contact with the photosensitive drum 1 in the forward rotation also performs a predetermined rotation operation.
[0064]
Here, the operation of the above-described first embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 4 is a diagram showing an operation sequence of the above-described image forming apparatus according to the first embodiment of the present invention.
[0065]
As shown in FIG. 4, in order to generate a rotation speed difference between the intermediate transfer belt 11 and the charge removing roller 21, which is a feature of the present invention, the rotation process speed of the intermediate transfer belt 11 is reduced from 120 mm / sec. The speed was increased to 160 mm / sec.
[0066]
Further, a charge of minus 3 kV was applied to the discharging roller 21 during the idling operation. Here, the charge removing roller 21 is in contact with the intermediate transfer belt 11 in a forward rotation.
[0067]
Due to the generated relative speed difference, a frictional force is generated between the intermediate transfer belt 11 and the charge removing roller 21, and an operation occurs in which the intermediate transfer belt 11 and the charge removing roller 21 mutually grind each other. Accordingly, it is possible to remove foreign matters such as scraps and dust remaining on the intermediate transfer belt 11 and the surface of the charge removing roller 21, thereby achieving high-quality and stable image formation.
[0068]
By the way, in the present embodiment, the contact pressure of the cleaning blade 16 contacting the intermediate transfer belt 11 is set to 20 gr / cm, and the result of the durability test in the environmental test room at 32 ° C. and 75% where the environmental conditions are high temperature and high humidity is shown. At 20,000 sheets, defective toner fusion spots and oil streaks, which are considered to be due to charge products, have been found to be defective. Even after 25,000 sheets have passed, good conditions are maintained. That was confirmed.
[0069]
In this experiment, the evaluation was performed by continuously copying an image having an image ratio of about 25% in an A4 size landscape mode in the endurance mode.
[0070]
In the present embodiment, the case where the intermediate transfer belt 11 is used as the intermediate transfer body has been described. However, as shown in FIG. 3, for example, as shown in FIG. A similar effect was confirmed.
[0071]
The intermediate transfer drum 20 is endless, and a rubber, an elastomer, or a sponge layer is included in any of the layers, so that the surface of the intermediate transfer drum 20 can have appropriate elasticity. A device for suppressing an increase in damage to the photosensitive drum 1 as compared with the intermediate transfer belt 11 of the system is added.
[0072]
(Second embodiment)
Next, a second embodiment of the image forming apparatus according to the present invention will be described. The configuration of the second embodiment is substantially the same as the configuration of the first embodiment described with reference to FIG. 1 described above, and a detailed description thereof will be omitted.
[0073]
The purpose of the second embodiment is to focus on the above-described first embodiment at a certain copy number interval while always avoiding the sequence as in the first embodiment during non-image formation. High image quality and high stability are achieved by utilizing the polishing ability enhancement utilizing the relative speed difference. The operation sequence of the second embodiment will be described with reference to FIG. FIG. 5 shows an operation sequence of the image forming apparatus according to the second embodiment of the present invention.
[0074]
However, as shown in FIG. 5, in this operation sequence, the number of times of polishing is naturally reduced as compared with the first embodiment, and this reduction must be covered by another means. In the present embodiment, the process speed of one rotation of the intermediate transfer belt 11 during non-image formation is increased to 200 mm / sec from 120 mm / sec during image formation, and at the same time, the rotation process speed of the charge removing roller 21 is also increased. This was achieved by pushing up from 120 mm / sec to 150 mm / sec and increasing the number of times of polishing between the intermediate transfer member 11 and the charge removing roller 21.
[0075]
The present embodiment is particularly effective in an image forming apparatus having no two-sided continuous copy version. In the executed sequence, the sequence of the present embodiment is input once every 5,000 copies, and unnecessary By not increasing the number of times of polishing, the life of the intermediate transfer belt 11 and the charge removing roller 21 and the life of the cleaning blade 16 were extended.
[0076]
Incidentally, in the prior art, at 32 ° C. and 75% in a high-temperature and high-humidity environment, image blur toner fusing streaks and spots due to poor charging occurred on 20,000 sheets or less, but in the present embodiment, It was confirmed that the cleaning property was maintained up to 30,000 sheets by single-sided A4 size lateral feeding and one sheet intermittent copy.
[0077]
(Third embodiment)
Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 3 is a partial configuration diagram of a third embodiment of the image forming apparatus according to the present invention, and FIG. 6 is a diagram illustrating an operation sequence of the third embodiment of the image forming apparatus according to the present invention.
[0078]
However, among the members shown in FIG. 3, the same members as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 3, the third embodiment of the image forming apparatus according to the present invention is different from the above-described first embodiment of the image forming apparatus according to the present invention in the first embodiment. An intermediate transfer drum 20 is used in place of the intermediate transfer belt 11 used in the embodiment, and the other points are the same.
[0079]
Although the purpose of this embodiment is the same as that of the second embodiment described above, the present embodiment is particularly effective for an image forming apparatus using a toner on the intermediate transfer drum 20 which is very easily fused. .
[0080]
As an experimental evaluation of the present embodiment, an external additive in the toner used in the first and second embodiments (particularly, as a cleaning aid, is used to serve as a lubricant and an abrasive). In a system in which a certain amount of strontium titanate was introduced, a strong fusing substance (commonly known as filming) was generated in a portion corresponding to a white background portion of the image forming section as the number of copies increased. The number of generated sheets was 20,000 or less in a high-temperature and high-humidity environment at 32 ° C. and a 75% environment.
[0081]
For this reason, as is clear from the operation sequence shown in FIG. 6, in order to make the polishing property stronger than that of the second embodiment described above, the charge removal is performed before the image formation and during the non-image formation after the image formation. The roller 21 is stopped, and only the intermediate transfer drum 20 is rotated at a process speed of 120 mm / sec, and a polishing force is generated between the neutralizing roller and the intermediate transfer member in the first and second embodiments or more, and the intermediate Filming adhered to the transfer drum could be removed. At this time, one side, A4 size horizontal feed, and one intermittent copy were performed.
[0082]
In this embodiment, the sequence is performed every 5,000 sheets in consideration of avoiding damage to the intermediate transfer drum 20 and the charge eliminating roller 21.
[0083]
(Fourth embodiment)
Next, a fourth embodiment of the image forming apparatus according to the present invention will be described. This embodiment further improves the effects of the third embodiment described above, and is particularly applicable to a high-speed color copying machine having a higher processing speed than the image forming apparatus described in the third embodiment. is there.
[0084]
Therefore, the configuration is the same as the configuration shown in FIG. FIGS. 7 and 8 are diagrams showing the operation sequence of the fourth embodiment.
[0085]
In the present embodiment, the present invention is applied to a high-speed copying machine having a process speed as high as 160 mm / sec. A drum having a diameter of 180 mm was used in response to the increase in speed (see FIG. 7).
[0086]
As an experimental evaluation, an evaluation mode similar to that of the above-described third embodiment was performed. In the prior art, filming occurred at 5,000 copies, but in this embodiment, non-filming was performed. The process speed of the photosensitive drum 1 during image formation is set to V2 = 180 mm / sec, which is higher than the process speed (V1 = 120 mm / sec) during image formation, and the charge removing roller 21 is stopped. The removal of firmly adhered filming became possible.
[0087]
By the way, the sequence of the present embodiment was able to achieve the target copy number of 20,000 sheets by inserting every 5,000 sheets. At this time, the A4 size horizontal feed was one intermittent copy.
[0088]
Further, as a mode in which the completely same effect was confirmed, during non-image formation, on the contrary, the intermediate transfer drum 20 was stopped, and the rotation process speed of the charge eliminating roller 21 was reduced to the process speed during image formation (V3 = 120 mm / (Sec) Even in a state where V4 = 180 mm / sec, which is larger than the above, it is possible to obtain substantially the same effect as described above. The image used had a duty ratio of 25% (see FIG. 8).
[0089]
Here, when the conveyance rotation speed of the discharging roller 21 is V3 and the conveyance rotation speed at the time of image formation is V3> V4 while the intermediate transfer drum 20 is not rotating during non-image formation. It is.
[0090]
(Fifth embodiment)
Next, a fifth embodiment of the image forming apparatus according to the present invention will be described. The configuration of the fifth embodiment is similar to the configuration of the first embodiment described with reference to FIG. The operation sequence of the fifth embodiment will be described with reference to FIGS. 9, 10 and 11. FIGS. 9, 10 and 11 are diagrams showing an operation sequence of the image forming apparatus according to the fifth embodiment of the present invention.
[0091]
The purpose of the present embodiment is to reduce the number of external additives in the toner in order to reduce the occurrence of filming and the like. The main purpose is to suppress the occurrence.
[0092]
Reducing the amount of external additives (especially abrasives) in the toner suppresses damage (durability, scratches, etc.) to the photoconductor, delays the occurrence of image defects such as scratches due to scratches, and shortens the life of the photoconductor. However, on the other hand, the amount of abrasion of the photoreceptor is reduced, and the ability to remove fusion products which inhibits the charging ability of the photoreceptor and the transfer member surface is reduced. An abnormal image such as an image or a spot is generated.
[0093]
Here, in the present embodiment, as a countermeasure, especially in a high-temperature and high-humidity environment, the polishing force increasing sequence between the intermediate transfer belt 11 and the neutralizing roller 21 found in the above-described first embodiment and the like is adopted. In order to improve the polishing power more than the sequence in the environment other than the high humidity environment, a sequence for changing the polishing power in accordance with the environmental conditions in the apparatus is introduced.
[0094]
Conversely, it does not require much polishing power, for example, in a low-temperature and low-humidity environment, so that unnecessary polishing power does not operate, and unnecessarily reduce the life around the transfer belt. did.
[0095]
As an embodiment, the environmental conditions are divided into three sections, and I (in-machine temperature of 20 ° C to less than 30 ° C, humidity of 10% to less than 60%), II (in-machine temperature of 30 ° C to less than 45 ° C, humidity of 60% to 80%). %) And III (in-machine temperature of 45 ° C. or more, humidity of 80% or more). Other combinations were assigned to categories based on humidity values.
[0096]
Under the environmental conditions of the category I, the process speed of the intermediate transfer belt during the non-image formation in the above-described first embodiment was set to 140 mm / sec (see FIG. 9).
[0097]
Under the environmental conditions of the category II, the operation sequence was the same as that of the first embodiment (see FIG. 10). That is, the process speed during non-image formation of the intermediate transfer belt was set to 160 mm / sec.
[0098]
Under the environmental conditions of the category III, the process speed of the intermediate transfer belt 11 during non-image formation in the above-described first embodiment was set to 180 mm / sec (see FIG. 11).
[0099]
As a result, the polishing force between the transfer belt 11 and the charge removing roller 21 can be increased in accordance with the environmental conditions with respect to fusing streaks and spots which are likely to occur at high temperature and high humidity, and efficient high image quality stabilization can be achieved. It is now possible to create a sequence.
[0100]
Further, the same effect as described above could be achieved by forming a sequence corresponding to another environmental condition.
[0101]
In the section I, the number of rotations of the intermediate transfer belt was set to 3 in correspondence with the above-mentioned environmental section in the image forming apparatus. In Category II, the number of rotations of the intermediate transfer belt was four. In Category III, the number of rotations of the intermediate transfer belt was set to 5 rotations. However, in the image forming apparatus according to the present invention, the number of rotations of the intermediate transfer belt is not limited to these numbers, and may be appropriately changed.
[0102]
As described above, the same effect as described above was achieved by making the rotation speed of the intermediate transfer belt 11, that is, the time for polishing in contact with the charge removing roller 21 correspond to the environmental conditions.
[0103]
By the way, according to the conventional example, 15,000 sheets were obtained under the condition of the above-mentioned external additive strontium titanate titanate amount of 0.2% (% by weight) in a toner at 32 ° C. and 75% in a high temperature and high humidity environment. With the following number of copies, the fusing streaking and spotting occurred when the power was turned on at the start of the operation. It was confirmed that 10,000 or more sheets were prevented from fusing lines and spots. At this time, A4 landscape feed, image duty ratio 6%, and intermittent copy were performed.
[0104]
Here, the control of the rotation speed or the rotation speed of the intermediate transfer belt 11 during non-image formation is arithmetically controlled by a control circuit (not shown) according to the environment. The control transmission system converts conditions detected by a temperature / humidity sensor arranged in a paper feeding unit (not shown) of the image forming apparatus used in the present invention into signals, which are transmitted to the above-described control circuit arithmetic circuit, and transferred. It is sent to a belt drive motor control circuit to control the rotation of the transfer belt.
[0105]
【The invention's effect】
As is apparent from the above description, according to the present invention, since the intermediate transfer member and the charge removing means are driven with a relative speed difference, filming caused by long-term use without complicating the structure is achieved. Prevention of poor cleaning due to adhesion of silicone oil during printing and fixing, and at the same time, ensuring the cleaning performance of a simple system transfer body cleaning device and the elimination of electricity on the transfer body, thereby preventing the deterioration of image quality and achieving high quality image formation. An image forming apparatus capable of performing the above can be provided.
[Brief description of the drawings]
FIG. 1 is a partial configuration diagram of a first embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a partially enlarged view of the image forming apparatus shown in FIG.
FIG. 3 is a partial configuration diagram of a third embodiment of the image forming apparatus according to the present invention.
FIG. 4 is a diagram showing an operation sequence of the first embodiment of the image forming apparatus according to the present invention.
FIG. 5 is a diagram showing an operation sequence of the second embodiment of the image forming apparatus according to the present invention.
FIG. 6 is a diagram illustrating an operation sequence of an image forming apparatus according to a third embodiment of the present invention.
FIG. 7 is a diagram illustrating an operation sequence of an image forming apparatus according to a fourth embodiment of the present invention.
FIG. 8 is a diagram illustrating an operation sequence of an image forming apparatus according to a fourth embodiment of the present invention.
FIG. 9 is a diagram showing an operation sequence of a fifth embodiment of the image forming apparatus according to the present invention.
FIG. 10 is a diagram showing an operation sequence of a fifth embodiment of the image forming apparatus according to the present invention.
FIG. 11 is a diagram illustrating an operation sequence of an image forming apparatus according to a fifth embodiment of the present invention.
[Explanation of symbols]
1 Photosensitive drum
2 Primary charger
3 Blank exposure section
4a First Image Forming Unit
4b Second Image Forming Unit
4c Third Image Forming Unit
4d Fourth image forming unit
5 Cleaning device
8 Primary transfer bias roller
9 Support rollers
10 Opposing rollers
11 Intermediate transfer belt
11a Base layer
11b Surface layer
12 Secondary transfer bias roller
14 Fixing means
15 Pre-exposure lamp
16, 17 cleaning blade
18 Transfer material transport path
19 Opposing roller
20 Intermediate transfer drum
21 Static elimination roller
22 Static neutralizing roller facing ground member
100 Image Forming Apparatus Main Body
P transfer material

Claims (1)

An image carrier having a movable surface and on which a latent image is formed,
An intermediate transfer member for transferring the toner image formed on the image carrier to a sheet material,
A static eliminator for contacting the intermediate transfer member to eliminate the charge of the intermediate transfer member,
At the time of non-image formation, the drive of the charge eliminator is stopped to provide a relative speed difference between the drive speeds at the contact portion between the intermediate transfer body and the charge eliminator, and at the time of image formation, the relative speed difference is reduced. An image forming apparatus, which is not provided.

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