JP3991183B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer. The present invention relates to an improvement in an image forming apparatus.
[0002]
[Prior art]
As an example of a conventional image forming apparatus, for example, an intermediate transfer type image forming apparatus, for example, each color of black (K), yellow (Y), magenta (M), and cyan (C) around a photosensitive drum, for example. A developing device for the components, an intermediate transfer belt is disposed opposite to the photosensitive drum, and an unfixed toner image of each color component formed on the photosensitive drum for each rotation of the photosensitive drum is transferred to the intermediate transfer belt. In this case, the composite primary transfer image superimposed on the intermediate transfer belt is secondarily transferred to a recording medium such as paper or OHP to form a desired image on the recording medium. For example, see JP-A-5-323704).
Here, in this type of intermediate transfer type image forming apparatus, for example, a patch for process control (hereinafter abbreviated as a process control batch) on an intermediate transfer belt, for example, for positioning or density control of each color component image. ), And based on this, the position and density control of each color component image are performed.
In the secondary transfer portion, a contact type transfer device such as a transfer roll is often used from the viewpoint of reliably transferring the multiple transfer image on the intermediate transfer belt to a recording medium.
[0003]
By the way, in an image forming apparatus using such a contact-type transfer device, the procompact adheres to the transfer roll, and if it is left as it is, the procompatch on the transfer roll is placed on the back surface of the recording medium. The reverse transition occurs, and the back surface of the recording medium becomes dirty.
In order to solve such a technical problem, conventionally, for example, a blade type cleaner is disposed on the transfer roll, and the proccompact transferred to the transfer roll is cleaned.
[0004]
[Problems to be solved by the invention]
However, in such a conventional contact-type transfer device, the position of the procompact is usually created at a predetermined position in the width direction of the intermediate transfer belt, so that the region where the procompact is transferred is included in the peripheral surface of the transfer roll. The position is limited to a predetermined position in the axial direction.
For this reason, when cleaning the transfer roll peripheral surface with a cleaner, among the blades in contact with the transfer roll peripheral surface, the portion where the procompations have been transferred tends to deteriorate earlier than the other portions. A technical problem has been found that the lifetime of the product tends to be shortened.
In addition, there is a situation in which the blade is likely to be poorly cleaned due to the early deterioration of the blade, and the procompact etc. transferred to the transfer roll is not completely cleaned but reversely transferred to the intermediate transfer belt side. Arise.
[0005]
In order to solve such a technical problem, it is conceivable to apply a lubricant to the surface of the transfer roll.
However, when this type of countermeasure is adopted, it is difficult to supply an appropriate amount of lubricant to the transfer roll surface, and the lubricant tends to be excessively supplied.
For this reason, there is a technical problem that uneven application of the lubricant is likely to occur on the surface of the transfer roll, which easily leads to uneven transfer.
[0006]
Further, in the vicinity of the secondary transfer site, the toner image on the intermediate transfer belt is transferred to the recording medium, and therefore, floating toner or the like tends to be easily generated.
However, with respect to the recording medium supplied to the secondary transfer site, no special measures are taken to prevent adhesion of floating toner, and floating toner adheres to the background of the surface of the recording medium. A technical problem is found that the recording medium is easily fogged.
[0007]
The present invention has been made to solve the above technical problem, and provides an image forming apparatus capable of effectively preventing a recording medium from being contaminated by an image material such as toner.
In particular, according to the present invention, in an image forming apparatus using a contact-type transfer unit, it is possible to maintain a good cleaning performance by the cleaning unit over a long period of time while maintaining a good transfer performance. An image forming apparatus is provided.
[0008]
[Means for Solving the Problems]
As shown in FIG. 1, the present invention includes an image carrier 1 on which an image is formed and carried, and a contact transfer member 2 a that contacts at least the image carrier 1 during a transfer operation, and an image on the image carrier 1. Is disposed upstream of the transfer portion between the image carrier 1 and the transfer means 2 with respect to the transfer direction of the recording medium, the transfer means 2 for transferring the image to the recording medium 3, the cleaning means 5 for cleaning the surface of the contact transfer member 2a. And a conveyance member having a roll pair that is divided and arranged on a rotatable support shaft that conveys the recording medium 3 and extends in a direction orthogonal to the recording medium conveyance direction, and a support located in an area other than the roll pair of the conveyance member. Application means provided on the shaft and applying the lubricant 7 in a belt shape along the conveyance direction of the recording medium 3 to the side surface of the contact transfer member of the recording medium 3 before entering the transfer site with the rotation of the conveyance member that and a 4 The image forming apparatus according to claim.
[0009]
In such technical means, the image carrier 1 is not limited to a mode having only a latent image carrier, but also includes a mode in which an intermediate transfer body is combined with a latent image carrier, and further, a multi-cycle type. It is not limited to, and includes any of those that constitute a tandem type.
The transfer unit 2 is not limited to the contact type but may be a non-contact type. However, in order to maintain good transferability, it is preferable to use a contact type transfer unit having a contact transfer member 2a.
[0010]
Furthermore, the location where the lubricant is applied may be on one or both sides of the recording medium 3 before the transfer site.
That is, the application unit 4 may apply the lubricant 7 to the side surface of the non-image carrier 1 of the recording medium 3, or apply the lubricant 7 to the side surface of the image carrier 1 of the recording medium 3. You may apply | coat and may apply | coat both surfaces.
Here, as the lubricant 7, when applied to the recording medium 3, the recording medium 3 is lubricated to improve the releasability of the image material such as toner (it is difficult for the image material such as toner to adhere). It may be fixed or liquid as long as the recording medium 3 is lubricated.
[0011]
Further, from the viewpoint of maintaining good cleaning performance by the cleaning unit 5, the coating unit 4 includes a contact transfer member region corresponding to a process control image formed in at least a non-image forming region of the image carrier 1. The lubricant 7 may be applied to the region to be covered.
The cleaning means 5 mentioned here is of course a system using a cleaning blade or a cleaning brush arranged in contact with the contact transfer member 2a, but a bias having a polarity opposite to that of the image material such as toner is applied. It also includes a mode in which an image material such as toner adhering to the contact transfer member 2a is transferred to the image carrier 1 side by application.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 is an explanatory view showing Embodiment 1 of the image forming apparatus to which the present invention is applied.
In the figure, reference numeral 21 denotes a photosensitive drum (latent image carrier) that rotates in the direction of arrow A, for example, 22 denotes a charging device such as a charging roll that precharges the photosensitive drum 21, and 23 denotes based on each color component image information. An image writing device such as a laser scanning device (ROS) that writes an electrostatic latent image corresponding to each color component on the photosensitive drum 21 (in this example, a beam is attached to the beam from the device), and 24 is yellow (Y) , Developing units 241 to 244 corresponding to the colors magenta (M), cyan (C), and black (K) are rotary type (rotary type) developing devices mounted on the rotary holder 245 and formed on the photosensitive drum 21. The electrostatic latent image thus formed is developed by any one of the developing devices 241 to 244 to form each color component toner image T. Reference numeral 25 denotes a drum cleaner that removes residual toner on the photosensitive drum 21 as waste toner, and reference numeral 26 denotes a static elimination roll that removes residual charge on the photosensitive drum 21.
[0013]
Reference numeral 30 denotes an intermediate transfer belt made of semiconductive polyimide having a thickness of, for example, 80 μm and disposed so as to be in contact with the surface of the photosensitive drum 21, and a plurality of (for example, five in the present embodiment). The rolls 31 to 35 are stretched to rotate in the direction of arrow B.
Further, at a portion (primary transfer position) facing the photosensitive drum 21 of the intermediate transfer belt 30, a primary transfer device (a primary transfer roll made of urethane foam in the present embodiment) is provided on the back side of the intermediate transfer belt 30. 27 is provided, and a toner image on the photosensitive drum 21 is electrostatically attracted to the intermediate transfer belt 30 by applying a voltage having a polarity opposite to the charging polarity of the toner to the primary transfer roll 27. It has become.
[0014]
Here, we describe the tension roll 31 to 35 of the intermediate transfer belt 30 used in this embodiment, reference numeral 31 a driving roll provided near the upstream side of the primary transfer region by the primary transfer roll 27, 32 is a primary In order to keep the posture of the intermediate transfer belt 30 at the transfer portion in a predetermined posture, a driven roll (posture holding roll) 33 is provided on the extension line of the drive roll 31 and the primary transfer roll 27 , and 33 is downstream of the driven roll 32. A tension roll provided on the side for applying a predetermined tension to the intermediate transfer belt 30 , 34 a follower roll disposed further downstream of the tension roll 33, and 35 an element of a secondary transfer device 40 described later. It is an opposite roll (backup roll).
[0015]
Furthermore, a secondary transfer device 40 is disposed at the secondary transfer position of the intermediate transfer belt 30 facing the conveyance path of the paper P as a recording medium. In this embodiment, the toner of the intermediate transfer belt 30 is disposed. A secondary transfer roll 37 in which a smooth layer is coated on the surface of an elastic layer such as a foam, which is disposed in pressure contact with the image carrying surface, and a secondary transfer roll 37 disposed on the back side of the intermediate transfer belt 30. And an opposing roll (backup roll) 35 that forms electrodes.
In this embodiment, the secondary transfer roll 37 is grounded, and the transfer power circuit 38 is connected to the backup roll 35 via the power supply roll 36, so that the toner is charged during the transfer operation. A bias (for example, −3.1 kV) having the same polarity as the polarity (negative polarity) is stably applied. In the embodiment, a reverse polarity bias (for example, +500 V) is applied for a predetermined time after the secondary transfer operation is performed.
Further, in the present embodiment, a roll cleaner 41 is attached to the secondary transfer roll 37, and this roll cleaner 41 has a cleaning blade 41 a that contacts the secondary transfer roll 37. The transferred proccompact and the like are scraped off by the cleaning blade 41a.
Reference numeral 42 denotes a belt cleaner that removes residual toner on the intermediate transfer belt 30.
[0016]
Furthermore, in the present embodiment, the paper transport system sends the paper P from the paper tray 50 to the predetermined transport path by the feed roll 51, and transports the paper P by the transport roll 52 in the transport path. In addition, after the positioning of the paper P is temporarily stopped by the registration roll (registration roll) 53, the paper P is transported to the secondary transfer position at a predetermined timing, and the paper P after the secondary transfer is transported to the transport belt 54. The sheet is conveyed to the fixing device 60 by the conveyance belt 54 and discharged by the discharge roll 61.
[0017]
In particular, in the present embodiment, the lubricant application mechanism 70 is disposed in front of the secondary transfer site.
The lubricant coating mechanism 70, for example, as shown in FIG. 3, which are integrated in the resist roll 53 parts, as the resist roll 53, spaced intermediate portion of the support shaft 531 and 532 extending in the axial direction Roll pairs 53a and 53b each comprising a drive roll 533 and a driven roll 534 are provided on both sides, and a nylon application brush 71 is fixed to an intermediate portion of a support shaft 531 on the drive roll 533 side of the roll pairs 53a and 53b. In this application brush 71, a lubricant bar 72 elastically biased by a leaf spring 73 is arranged in contact.
In the present embodiment, the application brush 71 is disposed at a position corresponding to a position of a procompact (not shown) formed on the intermediate transfer belt 30, and the lubricant bar 72 is made of Zn-St. (Zinc stearate) is used, and the amount of biting into the lubricant bar 72 of the application brush 71 is set to about 4 mm.
[0018]
Next, the operation of the image forming apparatus according to the present embodiment will be described.
In the present embodiment, after a procompact for each color component image is sequentially formed on the intermediate transfer belt 30, an image forming cycle for each color component image is executed based on the procompatch.
At this time, each of the procompatches on the intermediate transfer belt 30 is not particularly applied with a secondary transfer bias when passing through the secondary transfer site, but is in direct contact with the secondary transfer roll 37. The patch is transferred to the secondary transfer roll 37 side.
In order to reduce the amount of transfer of the toner forming the procompact to the secondary transfer roll 37 when the procompact passes the secondary transfer roll 37, a bias having a polarity opposite to the charging polarity of the toner is applied. Is also possible.
On the other hand, when the paper P transported by the paper transport system passes through the resist roll 53, the application brush 71 comes into contact with the back side thereof, and the lubricant supplied from the lubricant bar 72 is applied via the application brush 71. Is done.
In this state, since the lubricant is applied to the back surface of the paper P, the toner releasability on the back surface of the paper P is improved. It becomes difficult to stick to the back.
[0019]
Thereafter, when the paper P coated with the lubricant passes through the secondary transfer portion, a secondary transfer bias is applied, and the multiple transfer image on the intermediate transfer belt 30 is transferred to the paper P side.
At this time, since the lubricant applied to the back surface of the paper P is transferred to the secondary transfer roll 37 side, the toner releasability on the surface of the secondary transfer roll 37 is improved. Not only does the toner forming the patch and the floating toner hardly adhere, but the toner attached to the secondary transfer roll 37 is easily scraped by the blade 41a of the roll cleaner 41, and the cleaning performance by the blade 41a is kept good. It is.
Further, since the lubricant supplied to the secondary transfer roll 37 is supplied to the tip of the blade 41a, the lubricant is given to the blade 41a, and damage to the blade 41a is suppressed to a small extent.
[0020]
Furthermore, in this embodiment, since the lubricant is indirectly supplied to the secondary transfer roll 37 via the paper P, a small amount of lubricant is applied to the surface of the secondary transfer roll 37. Further, uneven coating due to excessive supply of lubricant does not occur, and uneven transfer due to uneven coating is effectively avoided.
Furthermore, after the secondary transfer operation is completed, a reverse bias acts on the secondary transfer roll 37, so that residual toner adhering to the secondary transfer roll 37 is transferred to the intermediate transfer belt 30 side. The transferred toner is collected by the belt cleaner 42.
At this time, since the toner releasability on the surface of the secondary transfer roll 37 may be due to the presence of the lubricant, the toner on the secondary transfer roll 37 is easily transferred to the intermediate transfer belt 30 side.
When a reverse bias is applied to the secondary transfer roll 37, a part of the lubricant on the secondary transfer roll 37 is transferred to the intermediate transfer belt 30 side together with the residual toner, and the transferred lubricant is collected by the belt cleaner 42. Is done.
At this time, the lubricant reversely transferred to the intermediate transfer belt 30 is a part after the lubricant supplied onto the secondary transfer roll 37 via the paper P is cleaned by the roll cleaner 41, and thus a very small amount. However, there is no concern that the lubricant reversely transferred to the intermediate transfer belt 30 causes a change in releasability of the intermediate transfer belt 30 and causes density unevenness .
[0021]
Here, in the model of the present embodiment, a running test was performed to check whether or not the backside stain of the paper can be visually confirmed. As a result, the backside stain of the paper up to 25 kV in a low temperature and low humidity environment (10 ° C., 15%). Was confirmed.
In this regard, it has been confirmed that in the comparative form model that does not use the lubricant application mechanism 70, the backside of the paper is seen at about 7 kV.
[0022]
Further, when the contact angle at each position in the axial direction from the front side end position (BTR Out) on the surface of the secondary transfer roll 37 was examined, the result shown in FIG. 4 was obtained.
According to the figure, it is understood that 95 ° is obtained as the contact angle of the lubricant supply unit corresponding to the procompact, which is 5 ° higher than other portions (90 °).
This indicates that the wettability of the lubricant supply unit corresponding to the procompact is high on the surface of the secondary transfer roll 37, and the scraping property of the procompact by the cleaning blade 41a is kept good. I support that.
Further, since the contact angle of the secondary transfer roll 37 in the initial state was 97 °, it can be seen that the releasability is maintained over a long period of time by applying the lubricant.
[0023]
Further, the edge of the cleaning blade 41a of the roll cleaner 41 after 25 kV in a low temperature and low humidity environment, 5 kV in a high temperature and high humidity environment (28 ° C, 85%), and 10 kV in a low temperature and low humidity environment. FIG. 5A and FIG. 5B show a comparison between the state where the lubricant (Zn-St) is applied in the non-procompating region and the region where the lubricant is not applied in the non-procompating region. As shown in FIG. 5, it is confirmed that the portion where the lubricant is applied is less damaged at the edge of the cleaning blade 41a, and it is understood that the lubricity of the cleaning blade 41a is improved.
[0024]
Furthermore, in the model of the present embodiment, when the reverse transfer state of the lubricant toward the intermediate transfer belt 30 was examined, as shown in FIG. 6, a portion where the lubricant is applied in the procompat portion and other portions. It was confirmed that there was no change in the contact angle between
This has been confirmed that a small amount of lubricant that reversely transfers to the intermediate transfer belt 30 side is applied, and accordingly, uneven density does not occur.
That is, it is considered that the lubricant is applied in a large amount in the order of the paper P, the secondary transfer roll 37, and the intermediate transfer belt 30, and the releasability is good.
In FIG. 6, the inter image portion and the image portion are selected as positions from TR0 (reference position in the traveling direction of the intermediate transfer belt 30), and from the front end position (Belt Out) of the intermediate transfer belt 30. As a position in the axial direction, a plurality of points including the position of forming the procompact portion (145 mm to 155 mm) are selected, and the contact angle is examined for each.
[0025]
Embodiment 2
FIG. 7 is an explanatory view showing Embodiment 2 of the image forming apparatus to which the reference form of the present invention is applied.
In the drawing, the basic configuration of the image forming apparatus is substantially the same as that of the first embodiment. However, unlike the first embodiment, the lubricant application mechanism 70 is provided separately and independently on the downstream side of the resist roll 53. In addition, an application brush 71 extending over substantially the entire width direction of the paper P and an opposing roll 75 opposed thereto are disposed, and a lubricant bar 72 is provided on the entire area of the application brush 71 in the axial direction by a coil spring 74, for example. The application brush 71 is elastically energized and is rotated by a driving mechanism (not shown). The application brush 71 and the opposing roll 75 are arranged so that the application brush 71 contacts the surface side of the paper P. The paper P is allowed to pass between the two and the lubricant is applied to the entire surface side of the paper P.
In the present embodiment, unlike the first embodiment, a resist roll 53 is disposed immediately after the feed roll 51, and the same reference numerals as those in the first embodiment are the same as those in the first embodiment. Reference numerals are assigned and detailed description thereof is omitted here.
[0026]
Therefore, according to the present embodiment, the paper P is conveyed in a state where the lubricant is applied to the surface side before reaching the secondary transfer portion.
At this time, even if uncharged toner or weakly charged toner floats near the secondary transfer site or toner adheres to the background, these floating toner or background toner is electrostatically attracted. It tries to adhere to the surface of the paper P only by force such as van der Waals force, but not by force, but since the lubricant is applied to the surface of the paper P, toner releasability is present on the surface of the paper P. The toner is less likely to adhere.
Therefore, the concern that floating toner or the like adheres to the background of the surface of the paper P and fogging is effectively avoided.
[0027]
In the first embodiment, the lubricant coating mechanism 70, since incorporating the resist roll 53 parts, by utilizing the driving force of the registration roll 53 it is possible to exert a lubricant application mechanism 70.
In the first and second embodiments, the lubricant is applied to either side of the paper P. However, it goes without saying that the lubricant may be applied to both sides of the paper P.
[0028]
【The invention's effect】
As described above, according to the present invention, the recording medium is transported upstream of the transfer portion between the image carrier and the transfer unit and transports the recording medium and is orthogonal to the recording medium transport direction. A conveying member having a pair of rolls divided and arranged on a rotatable supporting shaft extending to the shaft, and provided on a supporting shaft located in a region other than the pair of rolls of the conveying member, and at a transfer site in accordance with the rotation operation of the conveying member. Since the recording medium is provided with a coating means for applying the lubricant in a strip shape along the recording medium conveyance direction to the contact transfer member surface side of the recording medium before entering, on the surface of the recording medium coated with the lubricant Further, it is possible to improve the releasability of the image material such as toner, and accordingly, it is difficult to attach the image material to the background or the like, and it is possible to effectively avoid the situation where the recording medium is soiled.
Particularly, in the image forming apparatus using the contact-type transfer unit, since the lubricant is applied to the side surface of the contact transfer member of the recording medium, it is possible to give a lubricating action to the cleaning unit. The life of the cleaning means can be extended, and contamination of the recording medium due to poor cleaning can be reliably avoided.
Further, in this aspect, since the lubricant is indirectly applied to the contact transfer member via the recording medium, it is possible to apply a small amount of the lubricant, which is accompanied by excessive supply of the lubricant. Uneven coating is unlikely to occur. For this reason, it is possible to reliably avoid the occurrence of transfer unevenness due to application unevenness.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of an image forming apparatus according to the present invention.
FIG. 2 is an explanatory diagram illustrating an overall configuration of the image forming apparatus according to the first embodiment.
FIG. 3 is an explanatory diagram showing an example of a lubricant application mechanism used in the present embodiment.
FIG. 4 is a graph showing a change in contact angle of each part of a secondary transfer roll used in the present embodiment.
FIG. 5A is an explanatory view showing a state of a region where a lubricant is applied at a non-proccompatch position of the cleaning blade, and FIG. It is explanatory drawing which shows a state.
FIG. 6 is an explanatory diagram showing a change in contact angle of each part on the intermediate transfer belt side used in the present embodiment.
7 is an explanatory diagram showing an overall configuration of an image forming apparatus according to Embodiment 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image carrier, 2 ... Transfer means, 2a ... Contact transfer member, 3 ... Recording medium, 4 ... Coating means, 5 ... Cleaning means, 6 ... Process control image, 7 ... Lubricant

Claims (2)

An image carrier on which an image is formed and carried;
A transfer means having at least a contact transfer member that contacts the image carrier during a transfer operation and transferring an image on the image carrier to a recording medium;
Cleaning means for cleaning the surface of the contact transfer member;
It is divided and arranged on a rotatable support shaft that is disposed upstream of the transfer portion between the image carrier and the transfer unit in the recording medium conveyance direction, conveys the recording medium, and extends in a direction perpendicular to the recording medium conveyance direction. A conveying member having a pair of rolls ,
The conveyance direction of the recording medium with respect to the side surface of the contact transfer member of the recording medium which is provided on a support shaft located in a region other than the pair of rolls of the conveyance member and before entering the transfer site as the conveyance member rotates. An image forming apparatus comprising: an application unit that applies a lubricant in a belt shape along the line. The image forming apparatus according to claim 1.
The image forming apparatus characterized in that the applying means applies a lubricant to an area including a contact transfer member area corresponding to a process control image formed in at least a non-image forming area of the image carrier.

Images