JP5954630B2 - Intermediate transfer unit and image forming apparatus - Google Patents

Description

  The present invention relates to a transfer unit that transfers a toner image formed on an image carrier such as a photosensitive drum onto a recording medium via a belt-shaped intermediate transfer member, and an image forming apparatus including the transfer unit. is there.

Conventionally, a toner image is formed on an image carrier having a charging device, an exposure device, a developing device, etc. around it, and the toner image on the intermediate transfer member is recorded after primary transfer of the formed toner image to the intermediate transfer member. 2. Description of the Related Art An electrophotographic image forming apparatus that includes a transfer unit that performs secondary transfer onto a medium is known. Further, a configuration in which one image carrier is provided, a configuration in which a plurality of image carriers are provided on the extended surface of the intermediate transfer member for each toner color for image formation, and one for each toner color for image formation. An image forming apparatus having a configuration in which a plurality of developing devices are provided around an image carrier is also known.
In the transfer unit provided with the intermediate transfer member as described above, a tension roller is provided on the inner peripheral side of the belt-shaped intermediate transfer member, and the intermediate transfer member is pressed toward the outer peripheral side so that the intermediate transfer member does not loosen. There has been known a configuration in which a substantially constant tension is applied to.

  In such a transfer unit having a belt-like intermediate transfer member, when the recording medium enters the secondary transfer portion, a braking force acts in a direction to stop the movement of the intermediate transfer member, and a sudden tension is applied to the intermediate transfer member. Variations occur. Due to the tension fluctuation of the intermediate transfer member, shock vibration is generated in the intermediate transfer member and is transmitted to the image carrier during image formation or primary transfer. As a result, it is known that there may be a phenomenon (hereinafter referred to as shock jitter) in which color misregistration, color unevenness, striped density unevenness, and the like occur on the recording medium and cause image quality deterioration.

  In Patent Document 1, the occurrence of shock jitter caused by the vibration of the intermediate transfer member caused by the impact when the storage medium enters the secondary transfer unit is transmitted to the image carrier via the intermediate transfer member is suppressed. The following transfer unit is described. Attenuating means for attenuating the vibration is provided on a tension roller that keeps the tension of the intermediate transfer member provided between the secondary transfer roller and the driving roller on the inner peripheral side of the intermediate transfer member substantially constant. The damping means provided on the tension roller connects the inertial body to the rotating shaft of the tension roller via an elastic body having a spring function and a damper function. Such a damping means is provided on the rotating shaft of the tension roller, and the vibration generated in the secondary transfer portion is transmitted to the image carrier via the intermediate transfer body by the damping means provided on the tension roller to reduce the shock. It is intended to suppress jitter and improve image quality.

  In recent years, demands for higher image quality of image forming apparatuses and diversification of recording media on which image formation is performed by the image forming apparatuses have been increasing.

  The inventors conducted the following experiment in order to meet the demands for higher image quality and diversification of recording media on which images are formed by the image forming apparatus. First, in order to suppress the occurrence of shock jitter, the damping constant of the damping means is set so that the damping force of the damping means provided on the tension roller is suitable for the type of paper that is used frequently. did. Also, one end of the damping means for damping the vibration in the direction parallel to the pressing direction by the pressing means of the tension roller (hereinafter simply referred to as the pressing direction) is connected to the shaft that rotatably holds the tension roller. Provided. Then, an experiment for confirming the occurrence of shock jitter at a linear velocity in the moving direction of a plurality of intermediate transfer members was performed using a paper type of a recording medium that is frequently used. Then, depending on the linear velocity in the moving direction of the intermediate transfer member, a phenomenon in which shock jitter is more likely to occur occurs in the configuration in which the damping roller is not provided with the damping unit than in the configuration in which the tension roller is not provided with the damping unit. confirmed.

  This phenomenon is also considered to occur in the transfer unit described in Patent Document 1 in the following cases. The attenuation constant of the attenuation means is set so as to obtain an attenuation force suitable for the paper type of the frequently used recording medium. This is a case where the image formation is performed by changing the conditions such as the paper type of the recording medium and the linear velocity in the moving direction of the intermediate transfer body when actually forming the image.

  The present invention has been made in view of the above problems, and an object thereof is to provide the following transfer unit. It can cope with a wide range of conditions such as the type of paper of the recording medium and the linear velocity in the moving direction of the intermediate transfer member, and the shock jitter caused by the shocking vibration generated in the intermediate transfer member when the recording medium enters the secondary transfer portion. This is a transfer unit that can suppress generation.

  In order to achieve the above object, the invention described in claim 1 includes a belt-like intermediate transfer member to which a toner image is primarily transferred from an image carrier having a toner image formed on a surface thereof, and the image carrier. A primary transfer means for primarily transferring the toner image formed thereon onto the intermediate transfer member; and the intermediate transfer member from the inner peripheral side to the outer peripheral side of the intermediate transfer member or from the outer peripheral side of the intermediate transfer member to the inner side. A tension roller that applies pressure to the peripheral side to apply tension; a secondary transfer unit that secondarily transfers the toner image primarily transferred onto the intermediate transfer member onto the recording medium; and a tension roller in a pressing direction of the tension roller. A transfer unit including a damping unit that applies a damping force that attenuates vibration to the tension roller, and the transfer unit includes a selection unit that selects whether the damping force of the damping unit is applied to the tension roller. It is a thing.

According to the present invention, since the damping force of the damping means can be applied to the tension roller, it is difficult for the tension roller to suddenly change when the recording medium enters the secondary transfer portion, and shock jitter is generated. Can be reduced.
Further, in the case where the paper type of the recording medium on which the toner image is secondarily transferred, the linear velocity in the moving direction of the intermediate transfer member, and the like are provided, if the damping means is provided, the shock jitter tends to occur on the contrary. It is possible to prevent the damping force of the damping means from acting on the tension roller.
Accordingly, it is possible to cope with a wide range of conditions such as the paper type of the recording medium and the linear velocity in the moving direction of the intermediate transfer member, and to suppress the occurrence of shock jitter.

  The present invention can cope with a wide range of conditions such as the paper type of the recording medium and the linear velocity in the moving direction of the intermediate transfer member, and is caused by shock vibration generated in the intermediate transfer member when the recording medium enters the secondary transfer portion. A transfer unit that can suppress the occurrence of shock jitter.

1 is a schematic explanatory diagram of a printer that is an image forming apparatus according to an embodiment. Explanatory drawing about the structure around a tension roller. FIG. 3 is an explanatory diagram of a configuration that enables selection of a contact and separation of a damper with respect to a tension roller shaft according to the first embodiment. Explanatory drawing about the position fluctuation | variation of the tension roller by the presence or absence of attachment of a damper. Explanatory drawing of the specification of the damper used for experiment. Explanatory drawing of the structural example using the rubber | gum which is an elastic body as a damping means. The structural example of the damper which can adjust damping force based on Example 2. FIG. This is a connection example of a damper that can adjust the damping force.

  Hereinafter, an embodiment in which the present invention is applied to a color printer (hereinafter referred to as a printer 100) as an image forming apparatus employing an electrophotographic method will be described with reference to a plurality of examples. First, the configuration and operation of the printer 100 common to the embodiments will be described with reference to the drawings. Here, in the present embodiment, the present invention is based on a so-called intermediate transfer system in which the photosensitive drums 7Bk, 7C, 7M, and 7Y that are image carriers are provided on the upper stretched surface of the intermediate transfer belt 10 that is an intermediate transfer body. An example applied to the tandem printer 100 will be described. However, the present invention is not limited to this. For example, a configuration in which one photosensitive drum is provided, or a plurality of developing devices are provided for each color of toner that forms an image around one photosensitive drum. The present invention can also be applied to an image forming apparatus having a provided configuration. Further, the present invention is not limited to a printer, and can be applied to an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, and a multifunction machine.

  Here, FIG. 1 is a schematic explanatory diagram of a printer 100 that is an image forming apparatus according to the present embodiment, and FIG. 2 is an explanatory diagram of a configuration around a tension roller.

  As shown in FIG. 1, a printer 100 according to this embodiment includes a transfer unit 40 having an intermediate transfer belt 10 that is a belt-like intermediate transfer member as an image carrier, and four image forming stations. . The intermediate transfer belt 10 is supported so as to be stretched around a driving roller 11 and a tension roller 12. The image forming stations are arranged side by side along the upper extended surface of the intermediate transfer belt 10. The drive roller 11 for driving the intermediate transfer belt 10 is connected to a drive motor via a drive transmission system such as a gear of a drive device (not shown), and is a secondary transfer unit via the intermediate transfer belt 10. It also functions as a secondary transfer backup roller facing the transfer roller 4.

  Each image forming station has photosensitive drums 7Bk, 7C, 7M, and 7Y as image carriers, and a dedicated charging device, a developing device, and a cleaning (not shown) are arranged around each photosensitive drum 7. I have a device. In addition, toner bottles 9Bk, 9C, 9M, and 9Y that store toner to be supplied to each of the four image forming stations are disposed in the upper portion of the apparatus. The toner bottles 9Bk, 9C, 9M, and 9Y are filled with black (Bk), cyan (C), magenta (M), and yellow (Y) toners from the left in the drawing. Each toner bottle 9Bk, 9C, 9M, 9Y is replenished to the developing device of each color image forming station by a predetermined replenishment amount via a conveyance path (not shown).

  The image forming operation in the printer 100 configured as described above is performed as follows. As shown by a two-dot chain line in FIG. 1, a sheet P such as a recording sheet as a recording medium is fed from a sheet feeding cassette 1 by a sheet feeding roller 2, and the leading end of the sheet P reaches the registration roller pair 3. Detected by a sensor that does not. While taking timing with this detection signal, the registration roller pair 3 conveys the sheet P to the secondary transfer portion (nip portion) where the secondary transfer roller 4 as the secondary transfer member and the intermediate transfer belt 10 face each other. . On the other hand, the photosensitive drums 7Bk, 7C, 7M, and 7Y, which are uniformly charged in advance by the charging device of each image forming station, are exposed and scanned with a laser beam by an optical writing device (not shown), and the photosensitive drums 7Bk, An electrostatic latent image is created on 7C, 7M, 7Y. Each electrostatic latent image is developed by a developing device for each color, and black, cyan, magenta, and yellow toner images are formed on the surfaces of the photosensitive drums 7Bk, 7C, 7M, and 7Y.

  Next, a predetermined primary transfer bias voltage is applied to primary transfer rollers 8Bk, 8C, 8M, and 8Y as primary transfer means by a bias power source as primary transfer member bias application means (voltage application means) (not shown). The Then, the toner images on the photosensitive drums 7Bk, 7C, 7M, and 7Y are sequentially transferred onto the intermediate transfer belt 10. The image forming operation of each color in each image forming station is shifted in timing from the upstream side to the downstream side in the moving direction of the intermediate transfer belt so that the toner image is transferred to the same position on the intermediate transfer belt 10. Executed. The toner images of the respective colors formed on the intermediate transfer belt 10 are conveyed to a position opposite to the secondary transfer roller 4 as a secondary transfer member and are secondarily transferred onto the sheet P.

  The sheet P on which the toner image of each color is transferred is conveyed to the fixing device 5 and thermally fixed, and is discharged by a discharge roller (not shown). The residual toner on the photosensitive drums 7Bk, 7C, 7M, and 7Y is cleaned by the respective cleaning devices, and then charged simultaneously with the charge removal by the charging device in which the bias of the alternating current component is applied to the direct current. Prepare for the image forming (image forming operation) step. The residual toner on the intermediate transfer belt 10 is cleaned by a cleaning blade or the like of the intermediate transfer belt cleaning device 6 to prepare for the next image forming process.

  In the color image forming apparatus including the transfer unit 40 having the intermediate transfer belt 10 as in the printer 100 of the present embodiment, the secondary transfer is performed while the sheet P and the intermediate transfer belt 10 are brought into contact with each other at a relatively high pressure. There is a need to do. For this reason, when the sheet P enters the secondary transfer portion where the secondary transfer roller 4 and the intermediate transfer belt 10 face each other, a braking force for stopping the running of the intermediate transfer belt 10 at the secondary transfer portion is generated. Occur. Then, the belt tension on the downstream side in the belt movement direction of the secondary transfer portion increases rapidly, and the belt tension on the upstream side of the secondary transfer portion in the belt movement direction decreases rapidly. Then, speed fluctuations and tension fluctuations occur in the intermediate transfer belt 10, and these fluctuations are transmitted through the intermediate transfer belt 10 to be transmitted to the respective photosensitive drums 7 during image formation or primary transfer. Local image degradation is caused by causing fluctuations in the primary transfer pressure. It causes so-called shock jitter.

  In the transfer unit 40 of the present embodiment, as shown in FIG. 2, the tension roller 12 is pressed from the inner peripheral side to the outer peripheral side of the intermediate transfer belt 10 by a spring 14 that is a pressurizing unit, and thus the intermediate transfer belt 10. The intermediate transfer belt 10 is stretched while applying tension to the belt. When the sheet P enters the secondary transfer portion and the belt speed fluctuates, the tension of the intermediate transfer belt 10 upstream of the tension roller 12 in the movement direction of the intermediate transfer belt 10 increases, and the tension roller 12 is pulled. Due to this force, a sudden position change occurs in the tension roller 12. Since the tension roller 12 is pressed by the spring 14 as described above, vibration due to abrupt position fluctuation occurs, and this vibration is transmitted to the primary transfer portion to increase the fluctuation of the primary transfer pressure. Become.

  In order to prevent the above problem, in the present embodiment, as shown in FIG. 2, a damper 20 as a damping means is provided, and the damping force of the damper 20 is applied to the tension roller 12 to suppress the rapid position fluctuation. It is configured as follows. Here, in the present embodiment, a configuration in which the tension roller 12 applies pressure by applying pressure from the inner peripheral side to the outer peripheral side of the intermediate transfer belt 10 will be described. However, the tension roller 12 is provided on the outer peripheral side of the intermediate transfer belt 10. The present invention can also be applied to a configuration in which tension is applied by applying pressure toward the inner peripheral side.

  Next, the transfer unit 40 that can widely cope with conditions such as the sheet type of the sheet P and the linear velocity in the moving direction of the intermediate transfer belt 10 and can suppress the occurrence of shock jitter that occurs when the sheet P enters the secondary transfer portion. The configuration will be described with reference to a plurality of examples.

Example 1
First, Example 1 of the present embodiment will be described with reference to the drawings.
FIG. 3 is an explanatory diagram of a configuration that enables selection of contact and separation of the damper 20 with respect to the shaft 15 of the tension roller 12 according to the present embodiment. FIG. 4 is an explanatory view of the positional variation of the tension roller 12 depending on whether or not the damper 20 is attached. 4A is a method for measuring the positional displacement of the tension roller 12 in the X direction in the transfer unit 40, FIG. 4B is a positional variation when the damper 20 is not attached, and FIG. It is explanatory drawing of the position fluctuation | variation when attaching.

  FIG. 5 is an explanatory diagram of the specification of the damper 20 used in the experiment, and FIG. 6 is an explanatory diagram of a configuration example using rubber as an elastic body as the damping means.

  The inventors conducted the following experiment in order to meet the demands for higher image quality and diversification of recording media on which images are formed by the image forming apparatus. First, the damping force of the damper 20 provided on the tension roller 12 is set so that the damping force corresponding to the linear velocity in the moving direction of the intermediate transfer belt 10 suitable for a paper type having a frequently used sheet P can be obtained. A damping constant (maximum absorption capacity) was set. Further, one end of a damper 20 that attenuates vibration in the pressurizing direction by the spring 14 of the tension roller 12 is provided so as to be connected to a shaft 15 that rotatably holds the tension roller 12.

Then, an experiment for confirming the occurrence of shock jitter at the linear speed in the moving direction of the plurality of tension rollers 12 was performed using sheets of two types of paper types, a frequently used paper type and a thick paper type. Here, as the high paper type frequency of use, our Co., Ltd., trade name: My paper (basis weight of 68.5g / ^{m 2)} using a copy printing paper as thick paper (basis weight of 213.0g ^{/ m} 2) Was used.
Then, due to the linear velocity in the moving direction of the intermediate transfer belt 10, shock jitter is generated in the configuration in which the damper 20 is provided on the shaft 15 of the tension roller 12 than in the configuration in which the damper 20 is not provided on the shaft 15 of the tension roller 12. It was confirmed that a phenomenon that makes it easier to occur occurs.

As in the above experiment, the effect of the damper 20 on the shock jitter varies depending on the linear velocity in the moving direction of the intermediate transfer belt 10, and the experiment has resulted in the reverse effect due to the presence of the damper 20 under certain conditions. .
For this reason, in the present embodiment, whether or not to apply the damping force of the damper 20 to the shaft 15 of the tension roller 12 can be selected. Specifically, as shown in FIG. 3, the tension roller 12 holds the tension roller 12 rotatably, supports one end side of the spring 14, and abutment portion 24 of the damper 20 abuts on the tension roller 12. A shaft 15 on which a flat surface portion is formed is provided. In addition, an abutting portion 24 provided at the tip of the piston rod 23 on a bracket 22 in which a hydraulic (hereinafter referred to as oil type) damper 20 having a self-restoring force is fixed to the frame of the transfer unit 40 is provided on the tension roller 12 side. It is provided via a slide member so as to face. Then, on the side away from the tension roller 12 on the bracket 22, the damper 20 is pushed and pulled together with the slide member toward the tension roller 12, and the abutting portion 24 of the damper 20 is brought into contact with the flat portion of the shaft 15. A solenoid 21 to be separated is provided.

In this way, by providing the damper 20 so as to be able to come into contact with and away from the tension roller 12, the damping force of the damper 20 to the tension roller can be obtained when the damper 20 is provided. Can be prevented from working.
Therefore, it is possible to cope with a wide range of conditions such as the sheet type of the sheet P and the linear velocity in the moving direction of the intermediate transfer belt 10, which is caused by shock vibration generated in the intermediate transfer belt 10 when the sheet P enters the secondary transfer portion. It is possible to provide a transfer unit 40 that can suppress the occurrence of shock shock.
.

  The operation of the solenoid 21 to bring the damper 20 into and out of contact with the tension roller 12 is mainly based on the sheet type of the sheet P passing through the printer 100 and the linear velocity in the moving direction of the intermediate transfer belt 10. Need to work. In particular, the printer 100 according to the present embodiment is preferably configured so that the linear velocity in the moving direction of the intermediate transfer belt 10 is separated at less than about 90 mm / s and is brought into contact at about 90 mm / s or more. Could be suppressed. This was aimed at when the linear velocity in the moving direction of the intermediate transfer belt 10 was reduced, the speed of the tension roller 12 moving in the pressing direction was slow, and the balance with the damping constant of the damper 20 was poor. This is because a damping force cannot be obtained. As a result, the vibration of the tension roller 12 is transmitted through the damper 20 to the frame or the like of the transfer unit 40, causing the primary transfer portion to vibrate and causing image degradation. In order to suppress the occurrence of this phenomenon, it is necessary to separate the damper 20 from the tension roller 12 with the linear velocity in the moving direction of the intermediate transfer belt 10 being less than about 90 mm / s.

In the printer 100, a control unit (not shown) includes information such as a linear velocity in the moving direction of the intermediate transfer belt 10 and a detection result of a paper thickness sensor (not shown) provided in the sheet P conveyance path. Based on this, the solenoid 21 is controlled. In the case of a model not provided with a paper thickness sensor, when changing the paper type, the line speed at the time of setting the thick paper is set to 90 mm / mm based on information when the user sets the thick paper from the operation panel (not shown). When the thickness is set to less than s and thick paper is set, the damper may be separated.
As described above, by controlling based on the linear velocity in the moving direction of the intermediate transfer belt 10 and the paper type of the sheet P to be fed, the linear velocity in the moving direction of the intermediate transfer belt 10 and the sheet P of the sheet P are controlled. The effect of the attenuation means can be used more effectively for each species.

Next, a description will be given of the difference in the attenuation effect of the positional fluctuation in the pressing direction of the tension roller depending on whether or not the damper 20 is attached (contact or separation).
Here, the damper 20 shown in FIGS. 4B and 4C used when measuring the positional variation of each tension roller changes the linear velocity in the moving direction of the intermediate transfer belt 10 described above to change the shock jitter. The same standard as that used when the experiment was confirmed. As shown in FIG. 5, the details of the damper used in this experiment are as follows. The maximum absorption capacity is 2 [J], the absorption stroke is 5 [mm], the maximum collision speed is 1.0 [m / s], and the spring return force is 6 0.0 [N], a deflection angle of [1 ° or less], and a use temperature range of 0 to 60 [° C.] were used.

  Further, as shown in FIG. 4A, the tension roller 12 that stretches one end side of the locus of the intermediate transfer belt 10 in the transfer unit 40 is rotatably supported, and one end side of the spring 14 and the damper 20 is supported. The fluctuation of the axial center position of the shaft 15 was measured. Then, for each of the above conditions, the displacement on the X-axis with the movement of the axis of the shaft 15 toward the drive roller 11 as a positive direction is measured, and the sheet P enters the secondary transfer portion along the vertical axis. FIG. 4B and FIG. 4C are plots of the time since then plotted on the horizontal axis.

The inclination a1 in FIG. 4B indicates the speed of position fluctuation of the tension roller when the damper 20 is not attached, and the inclination a1 in FIG. 4C indicates the tension roller when the damper 20 is attached. The speed of position fluctuation is shown. 4B and 4C, the position fluctuation speed a1 when the damper 20 is not attached is larger than the position fluctuation speed a2 when the damper 20 is attached. (A2 <a1).
From this, it can be seen that abrupt positional fluctuations do not occur by attaching the damper 20. As a result, the adverse effect on the primary transfer portion can be suppressed, and the change in image density due to the spread of the image dot diameter in the primary transfer portion and the variation in the image dot pitch can be reduced. That is, it can be seen that the occurrence of shock jitter that occurs when the sheet P enters the secondary transfer portion can be suppressed.

Next, an example of a configuration using an elastic member made of rubber or the like having a small coefficient of restitution instead of the damper 20 as the damping means will be described with reference to FIG.
As shown in FIG. 6, instead of the damper 20 described with reference to FIG. 3, an elastic member 30 that is a damping member is provided between the abutting member 31 that abuts against the shaft 15 of the tension roller 12 as a damping means and the support member 32. Is attached. The elastic member 30 is made of rubber and is bonded to a support member 32 fixed to the bracket 22. Further, the support member 32 is installed on a slide member that is supported by the bracket 22 and moves in parallel. By moving the slide member with the solenoid 21, the abutting member 31 connected to the elastic member 30 is moved to the shaft 15 of the tension roller 12. Abutting on and separating from the flat portion.
Further, in this embodiment, the example using the oil type damper 20 and the elastic member has been described. However, the present invention is not limited to such a configuration. For example, a friction type having a self-restoring force or an electromagnetic type A damper may be used.

(Example 2)
Next, Example 2 of the present embodiment will be described with reference to the drawings.
The attenuating means provided in the transfer unit 40 of the present embodiment is different from the attenuating means provided in the transfer unit 40 of Embodiment 1 described above only in the following points. In contrast to the configuration of the first embodiment in which the damper 20 is provided so as to be able to contact and separate from the shaft 15 of the tension roller 12, the configuration of the present embodiment is in a connected state and the damping force of the damper 20 is increased. It is the point which concerns on having comprised so that adjustment is possible. Since the points related to other configurations and operations and the effects thereof are the same, the description will be omitted as appropriate.

  Here, FIG. 7 is a configuration example of the damper 20 that can adjust the damping force according to the present embodiment. FIG. 7A shows a case where the tension roller 12 vibrates at a low speed in the pressurizing direction, and FIG. 12 shows the state of the damper 20 when it vibrates at high speed in the pressurizing direction. FIG. 8 shows a connection example of a damper capable of adjusting the damping force.

In this embodiment, the damping force of the oil type damper 20 is adjusted as follows. As shown in FIGS. 7A and 7B, the damper 20 is provided with a valve 25 that can be opened and closed. By opening and closing the valve 25, the area of the flow path through which oil flows in the damper 20 is adjusted. That is, the damping force is changed by controlling the flow of oil in the damper 20. A damper having such a configuration is already known, and in this embodiment, the damping force is adjusted by using a damper having a configuration for adjusting the area of the flow path through which the oil flows.
By controlling the operation of the valve 25 in the damper 20 as described above, the degree of action of the damping force of the damper 20 varies depending on conditions such as the sheet type of the sheet P and the linear velocity in the moving direction of the intermediate transfer belt 10. Even in this case, an appropriate damping force can be applied to the tension roller 12.

The damper 20 is held by the bracket 22, and the abutting portion 24 provided at the tip of the piston rod 23 on the tension roller 12 side is connected to the flat portion provided on the shaft 15 of the tension roller 12. With this configuration, the piston rod 23 moves as the tension roller 12 moves in the pressurizing direction, and a damping force acts on the tension roller 12.
By configuring as described above, it is possible to cope with a wide range of conditions such as the sheet type of the sheet P and the linear velocity in the moving direction of the intermediate transfer belt 10, and the intermediate transfer belt 10 when the sheet P enters the secondary transfer portion. It is possible to provide the transfer unit 40 that can suppress the occurrence of shock jitter due to the shocking vibration that occurs.

Also in this embodiment, as in the first embodiment, the damping force of the damper 20 is controlled mainly based on the linear velocity in the moving direction of the intermediate transfer belt 10 and the information on the paper type of the sheet P to be passed. Do.
For example, when the control is performed based on the linear velocity in the moving direction of the intermediate transfer belt 10, the following control is performed. When the linear speed in the moving direction of the intermediate transfer belt 10 is a low speed of less than about 90 mm / s, as shown in FIG. 7A, the valve 25 is opened to reduce the damping force, and at a high speed of about 90 mm / s or more, FIG. As shown in (b), the valve 25 is closed to increase the damping force. By performing the control based on the linear velocity in the moving direction of the intermediate transfer belt 10 in this way, the effect of the damper 20 can be used more effectively for each linear velocity of the intermediate transfer belt 10.

Similarly, when controlling based on the paper type of the sheet P to be passed, the effect of the attenuation means can be used more effectively for each paper type of the sheet P.
Further, in the present embodiment, the example using the oil type damper 20 has been described. However, the present invention is not limited to such a configuration. For example, a friction type or an electromagnetic type damper with adjustable damping force is used. May be.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A belt-like intermediate transfer member such as an intermediate transfer belt 10 on which a toner image is primarily transferred from an image carrier such as a photosensitive drum 7 having a toner image formed on the surface, and the image carrier formed on the image carrier. Primary transfer means such as a primary transfer roller 8 that primarily transfers a toner image onto the intermediate transfer member, and the intermediate transfer member from the inner peripheral side to the outer peripheral side of the intermediate transfer member or the outer peripheral side of the intermediate transfer member Secondary transfer for secondary transfer of a tension roller such as a tension roller 12 that applies pressure by applying pressure toward the inner peripheral side from the toner and the toner image primarily transferred onto the intermediate transfer member onto a recording medium such as a sheet P A transfer unit such as a transfer unit 40, which includes a secondary transfer unit such as a roller 4 and a damping unit such as a damper 20 that applies a damping force to the tension roller to attenuate a vibration in a pressing direction of the tension roller; There are, in which is characterized in that whether to apply a damping force of the damping means to the tension roller is provided to be selected.
According to this, as described in the first embodiment, the following transfer unit can be provided. It can cope with a wide range of conditions such as the sheet type of the recording medium such as the sheet P and the linear velocity in the moving direction of the intermediate transfer member such as the intermediate transfer belt 10, and is recorded on the secondary transfer unit including the secondary transfer roller 4. This is a transfer unit such as the transfer unit 40 that can suppress the occurrence of shock jitter due to shock vibration generated in the intermediate transfer member when the medium enters.

(Aspect B)
In (Aspect A), whether or not to apply the damping force of the damping means such as the damper 20 to the tension roller such as the tension roller 12 is determined based on the linear velocity in the moving direction of the intermediate transfer member such as the intermediate transfer belt 10. The selection is based on information.
According to this, as described in the first embodiment, the effect of the damping means such as the damper 20 can be used more effectively for each linear velocity of the intermediate transfer member such as the intermediate transfer belt 10.

(Aspect C)
In (Aspect A), whether or not to apply the damping force of the damping means such as the damper 20 to the tension roller such as the tension roller 12, the paper of the recording medium such as the sheet P on which the toner image is secondarily transferred is determined. It is characterized by selecting based on species information.
According to this, as described in the first embodiment, the effect of the damping means such as the damper 20 is more effectively used for each paper type of the recording medium such as the sheet P onto which the toner image is secondarily transferred. it can.

(Aspect D)
A belt-like intermediate transfer member such as an intermediate transfer belt 10 on which a toner image is primarily transferred from an image carrier such as a photosensitive drum 7 having a toner image formed on the surface, and the image carrier formed on the image carrier. Primary transfer means such as a primary transfer roller 8 that primarily transfers a toner image onto the intermediate transfer member, and pressurizing the intermediate transfer member from the inner peripheral side to the outer peripheral side of the intermediate transfer member to give tension. A tension roller such as a tension roller 12, secondary transfer means such as a secondary transfer roller 4 for secondary transfer of a toner image primarily transferred onto the intermediate transfer member onto a recording medium such as a sheet P, and the tension In a transfer unit such as a transfer unit 40 having a damping unit such as a damper 20 that applies a damping force to the tension roller to attenuate a vibration in the pressure direction of the roller, the damping unit includes the tension unit. It is obtained and wherein the magnitude of the damping force to be applied to the roller can be selected.
According to this, as described in the second embodiment, the damping of the damper 20 and the like depends on conditions such as the paper type of the recording medium such as the sheet P and the linear velocity in the moving direction of the intermediate transfer member such as the intermediate transfer belt 10. Even if the degree of action of the damping force of the means is different, an appropriate damping force can be applied to the tension roller such as the tension roller 12. Therefore, it is possible to cope with a wide range of conditions such as the paper type of the recording medium and the linear velocity in the moving direction of the intermediate transfer body, and the intermediate transfer when the recording medium enters the secondary transfer portion composed of the secondary transfer roller 4 and the like. It is possible to provide a transfer unit such as the transfer unit 40 that can suppress the occurrence of shock jitter due to shock vibration generated in the body.

(Aspect E)
In (Aspect D), the magnitude of the damping force that acts on the tension roller such as the tension roller 12 is selected based on the linear velocity information in the moving direction of the intermediate transfer member such as the intermediate transfer belt 10. It is a thing.
According to this, as described in the second embodiment, the effect of the damping means such as the damper 20 can be used more effectively for each linear velocity of the intermediate transfer member such as the intermediate transfer belt 10.

(Aspect F)
In (Aspect D), the magnitude of the damping force of the damper 20 or the like that acts on the tension roller such as the tension roller 12 is determined based on the paper type information of the recording medium such as the sheet P on which the toner image is secondarily transferred. It is characterized by selection.
According to this, as described in the second embodiment, the effect of the damping means such as the damper 20 can be used more effectively for each paper type of the recording medium such as the sheet P onto which the toner image is secondarily transferred. .

(Aspect G)
An image carrier such as a photosensitive drum 7 on which a toner image is formed, a belt-like intermediate transfer member such as an intermediate transfer belt 10 on which a toner image is primarily transferred from the image carrier, and the image carrier. Primary transfer means such as a primary transfer roller 8 for primary transfer of the toner image formed on the body onto the intermediate transfer body, and the intermediate transfer body from the inner peripheral side to the outer peripheral side or the intermediate transfer body A tension roller such as a tension roller 12 that applies pressure by applying pressure from the outer peripheral side to the inner peripheral side of the intermediate transfer member, and a toner image primarily transferred onto the intermediate transfer member 2 on a recording medium such as a sheet P A printer 100 including secondary transfer means such as a secondary transfer roller 4 for next transfer, and damping means such as a damper 20 that applies a damping force to the tension roller to attenuate vibration in the pressing direction of the tension roller. Such as In the image forming apparatus, in which is characterized in that whether to apply a damping force of the damping means to the tension roller is provided to be selected.
According to this, as described in the first embodiment, the following image forming apparatus can be provided. It can cope with a wide range of conditions such as the sheet type of the recording medium such as the sheet P and the linear velocity in the moving direction of the intermediate transfer member such as the intermediate transfer belt 10, and is recorded on the secondary transfer unit including the secondary transfer roller 4. This is an image forming apparatus such as the printer 100 that can suppress the occurrence of shock jitter caused by shock vibration generated in the intermediate transfer member when a medium enters.

(Aspect H)
An image carrier such as a photosensitive drum 7 on which a toner image is formed, a belt-like intermediate transfer member such as an intermediate transfer belt 10 on which a toner image is primarily transferred from the image carrier, and the image carrier. Primary transfer means such as a primary transfer roller 8 for primary transfer of the toner image formed on the body onto the intermediate transfer body, and the intermediate transfer body from the inner peripheral side to the outer peripheral side or the intermediate transfer body A tension roller such as a tension roller 12 that applies pressure by applying pressure from the outer peripheral side to the inner peripheral side of the intermediate transfer member, and a toner image primarily transferred onto the intermediate transfer member 2 on a recording medium such as a sheet P A printer 100 including secondary transfer means such as a secondary transfer roller 4 for next transfer, and damping means such as a damper 20 that applies a damping force to the tension roller to attenuate vibration in the pressing direction of the tension roller. Such as In the image forming apparatus, the damping means is obtained and wherein the magnitude of the damping force to be applied to the tension roller can be selected.
According to this, as described in the second embodiment, the damping of the damper 20 and the like depends on conditions such as the paper type of the recording medium such as the sheet P and the linear velocity in the moving direction of the intermediate transfer member such as the intermediate transfer belt 10. Even if the degree of action of the damping force of the means is different, an appropriate damping force can be applied to the tension roller such as the tension roller 12. Therefore, it is possible to cope with a wide range of conditions such as the paper type of the recording medium and the linear velocity in the moving direction of the intermediate transfer body, and the intermediate transfer when the recording medium enters the secondary transfer portion composed of the secondary transfer roller 4 and the like. It is possible to provide an image forming apparatus such as the printer 100 that can suppress the occurrence of shock jitter due to shock vibration generated in the body.

DESCRIPTION OF SYMBOLS 1 Paper feed cassette 2 Paper feed roller 3 Registration roller pair 4 Secondary transfer roller 5 Fixing device 6 Intermediate transfer belt cleaning device 7 Photosensitive drum 8 Primary transfer roller 9 Toner bottle 10 Intermediate transfer belt 11 Drive roller 12 Tension roller 14 Spring (Pressurizing means)
15 shaft (tension roller)
20 Damper 21 Solenoid 22 Bracket 23 Piston rod (damper)
24 Butting part 24
25 Valve (oil damper)
30 Elastic member 31 Butting member (rubber type)
32 Support member (Rubber type)
40 Transfer Unit 100 Printer P Sheet

JP 2008-076499 A

Claims (8)

A belt-like intermediate transfer member on which a toner image is primarily transferred from an image carrier having a toner image formed on the surface, and a toner image formed on the image carrier on the intermediate transfer member. A primary transfer unit that applies pressure to the intermediate transfer member from the inner peripheral side of the intermediate transfer member to the outer peripheral side or from the outer peripheral side of the intermediate transfer member to the inner peripheral side, and the intermediate transfer member Secondary transfer means for secondary transfer of the toner image primarily transferred onto the body onto the recording medium; damping means for applying a damping force to the tension roller to attenuate vibration in the pressing direction of the tension roller; In a transfer unit equipped with
A transfer unit, wherein a selection is made as to whether or not to apply a damping force of the damping means to the tension roller. The transfer unit according to claim 1,
A transfer unit, wherein whether or not to apply a damping force of the damping means to the tension roller is selected based on linear velocity information in the moving direction of the intermediate transfer member. The transfer unit according to claim 1,
A transfer unit, wherein whether to apply a damping force of the damping means to the tension roller is selected based on information on a paper type of the recording medium onto which a toner image is secondarily transferred. A belt-like intermediate transfer member on which a toner image is primarily transferred from an image carrier having a toner image formed on the surface, and a toner image formed on the image carrier on the intermediate transfer member. A primary transfer unit that performs the recording, a tension roller that applies tension by pressing the intermediate transfer member from the inner peripheral side to the outer peripheral side of the intermediate transfer member, and a toner image that is primarily transferred onto the intermediate transfer member. In a transfer unit comprising: a secondary transfer unit that performs secondary transfer onto a medium; and a damping unit that applies a damping force to the tension roller that attenuates vibration in the pressing direction of the tension roller.
The transfer unit, wherein the damping means is capable of selecting a magnitude of a damping force that acts on the tension roller. The transfer unit according to claim 4, wherein
A transfer unit, wherein a magnitude of a damping force applied to the tension roller is selected based on information on a linear velocity in a moving direction of the intermediate transfer member. The transfer unit according to claim 4, wherein
A transfer unit, wherein a magnitude of a damping force applied to the tension roller is selected based on information on a paper type of the recording medium onto which a toner image is secondarily transferred. An image carrier on which a toner image is formed on a surface, a belt-like intermediate transfer member on which a toner image is primarily transferred from the image carrier, and a toner image formed on the image carrier on the intermediate transfer A primary transfer means for primary transfer onto the body, and a tension for applying tension by pressing the intermediate transfer member from the inner peripheral side of the intermediate transfer member to the outer peripheral side or from the outer peripheral side of the intermediate transfer member to the inner peripheral side. A secondary transfer means for secondary transfer of the toner image primarily transferred onto the intermediate transfer member onto the recording medium, and a damping force for attenuating vibration in the pressing direction of the tension roller to the tension roller. In an image forming apparatus provided with an attenuating means to act,
An image forming apparatus characterized in that it can be selected whether or not to apply a damping force of the damping means to the tension roller. An image carrier on which a toner image is formed on a surface, a belt-like intermediate transfer member on which a toner image is primarily transferred from the image carrier, and a toner image formed on the image carrier on the intermediate transfer A primary transfer means for primary transfer onto the body, and a tension for applying tension by pressing the intermediate transfer member from the inner peripheral side of the intermediate transfer member to the outer peripheral side or from the outer peripheral side of the intermediate transfer member to the inner peripheral side. A secondary transfer means for secondary transfer of the toner image primarily transferred onto the intermediate transfer member onto the recording medium, and a damping force for attenuating vibration in the pressing direction of the tension roller to the tension roller. In an image forming apparatus provided with an attenuating means to act,
The image forming apparatus according to claim 1, wherein the damping means can select a magnitude of a damping force that acts on the tension roller.

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