JP4903597B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, or a multifunction peripheral, and more particularly to a wet image forming apparatus using a liquid developer.

    At present, as a developing method applied to an image forming apparatus such as a printer, a copying machine, or a multifunction machine, a dry developing method is mainly used because of the ease of handling and simplicity of the developer. However, development of a wet image forming apparatus using a liquid developer instead of a dry developer has been actively promoted. This liquid developer is mainly composed of an insulating liquid (carrier liquid) such as dimethylpolysiloxane oil and a toner that is colored particles for visualization that are suspended in the liquid. Since the toner can be suspended in the liquid, the particle diameter of the toner can be made extremely small, and a high-quality image can be obtained. In particular, by reducing the particle diameter of the toner, a high-quality color image without graininess can be easily obtained.

  FIG. 5 (a) is a schematic configuration diagram of a printing mechanism in the wet image forming apparatus. An intermediate transfer belt B1, which is an intermediate transfer body, is stretched between three rollers, an intermediate transfer driving roller 63a, an intermediate transfer tension roller 63b, and an intermediate transfer driven roller 63c. As the intermediate transfer driving roller 63a rotates, the intermediate transfer belt B1 rotates in the direction of arrow F.

  Below the intermediate transfer belt B1, image forming means FY, FC for forming toner images for each color of yellow (Y), cyan (C), magenta (M), and black (B) from the upstream in the circulation direction. FM and FB are provided. At the nip portion where the intermediate transfer belt B1 is sandwiched between the latent image carrier RY of the image forming unit FY and the primary transfer roller 61Y, the primary transfer of the polarity opposite to the toner charging polarity is performed on the primary transfer roller 61Y (primary transfer unit). Since a bias voltage is applied, the yellow toner image is primarily transferred from the latent image carrier RY to the intermediate transfer belt B1. Since the carrier liquid is insulative, primary transfer is not performed, but the carrier liquid moves when a slight amount adheres to the intermediate transfer belt B1.

  Hereinafter, in the same manner, when the cyan, magenta, and black toner images are sequentially primary transferred to the intermediate transfer belt B1 and passed through the black image forming unit FB, a full-color toner image is formed on the intermediate transfer belt B1. Is formed. In this way, a method for forming a full color image by arranging image forming means for each color in series is called a tandem method.

  The full-color toner image formed in this way is transferred onto the recording medium K conveyed in the conveyance path L by a secondary transfer roller (secondary transfer means) 62 to which a bias having a polarity opposite to that of the toner is applied. The image is transferred and printing of one image is completed. After the secondary transfer, the developer (toner and carrier liquid) remaining on the intermediate transfer belt B1 is removed from the intermediate transfer belt B1 by the intermediate transfer belt removing means B2.

  More specifically, at the position of the intermediate transfer driven roller 63c, the removal blade B3 and the removal roller B4 in the removal unit B2 come into contact with the surface of the intermediate transfer belt B1, and scrape off the developer on the surface. Here, the removal blade B3 and the removal roller B4 are not necessarily provided as a pair. That is, the developer can be scraped off even if only one of the removal blade B3 and the removal roller B4 is provided. However, the use of a pair increases the efficiency of scraping off the developer.

The developer thus scraped off falls into the tank B5 due to gravity, and is collected and reused by a collecting device (not shown). An image forming apparatus including such a removing unit B2 is disclosed in, for example, Patent Documents 1 and 2 below.
JP 2001-109346 A JP 2002-296918 A

  However, the above prior art has the following problems.

  When the image formation is stopped, if the intermediate transfer belt B1 has been stopped for a certain period of time, the developer C that has been scraped off and collected above the removal blade B3 is removed by capillary action as shown in FIG. It passes over both sides in the longitudinal direction of the blade B3 and also turns to the back side of the removal blade B3, and adheres to the downstream side of the removal blade of the intermediate transfer belt B1. In particular, in the wet image forming apparatus using a liquid developer, such wraparound of the developer C frequently occurs. Since the developer C is mixed with toner of each color, the developer C has a black and cloudy color tone. If this wraparound is allowed, the following inconvenience occurs.

  That is, when the image formation is started again, the developer C that has gone around and adhered to the downstream side of the removal blade of the intermediate transfer belt is transported to the secondary transfer position as it is, and the nip between the secondary transfer means 62 and the intermediate transfer belt B1. The amount of carrier liquid in the nip becomes excessive. For this reason, the secondary transfer efficiency is lowered, and when the full-color image formed on the intermediate transfer belt B1 is secondarily transferred to the recording medium K, a transfer failure occurs and the image is disturbed. In addition, since the developer C has a turbid color, the leading edge of the paper becomes dirty. Further, when the latent image carrier RY of each image forming unit is not separated from the intermediate transfer belt B1, the developer C is blocked by the primary transfer nip, and the carrier liquid is excessively present in the primary transfer nip. The next transfer efficiency is lowered, and the image is deteriorated.

  The present invention has been made in view of such problems, and eliminates the influence of the residual developer that has passed around the end portion of the removal means of the intermediate transfer belt and adhered to the intermediate transfer belt, and has achieved high-quality images. An object of the present invention is to provide an image forming apparatus capable of forming images.

In order to achieve the above object, the present invention employs the following means.
First, the present invention includes a primary transfer unit that primarily transfers a toner image formed on a latent image carrier to an intermediate transfer member, a secondary transfer unit that transfers a toner image from the intermediate transfer member to a recording medium, Removing means for removing the residual developer from the transfer member.

  In such an image forming apparatus, a separation unit A that separates the intermediate transfer member from the secondary transfer unit after driving of the intermediate transfer member is stopped, and a separation unit B that separates the intermediate transfer member from the latent image carrier. Provide. Then, the contact means A starts the driving of the intermediate transfer body and after the movement time A required for the intermediate transfer body to move between the removal means and the secondary transfer means has elapsed, the intermediate transfer body and the secondary transfer body The means are brought into contact. That is, the secondary transfer is performed after waiting for the portion of the intermediate transfer belt removal blade to which the developer on the downstream side adheres to pass.

Furthermore, it may be configured to include an accelerating unit that makes the linear speed of the intermediate transfer body higher than the linear speed at the time of image formation from the start of driving of the intermediate transfer body until the elapse of the movement time B. That is, the portion to which the developer is attached is passed through quickly. The image forming here can be referred to as a linear speed when continuously outputting to a recording medium during a printing process, that is, a linear speed when forming a toner image on a latent image carrier. Further, after the driving time B required for the intermediate transfer member to move between the removing means and the latent image carrier from the start of driving of the intermediate transfer member, the intermediate transfer member and the latent image carrier are contacted. It is good also as a structure provided with the contact means B to contact.

  The present invention mainly assumes a wet image forming apparatus in which the primary transfer unit forms the toner image using a liquid developer composed of toner and a liquid carrier.

  As described above, according to the image forming apparatus of the present invention, the secondary transfer unit is separated until the residual developer attached to the intermediate transfer belt passes through the end of the intermediate transfer belt removing unit, It becomes possible to form a high-quality image that is not affected by the developer.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the position and size of the members are drawn with emphasis as appropriate in the drawings. In the following embodiments, a printer will be described as an example of the image processing apparatus of the present invention, but the present invention is not limited to this. In other words, the image processing apparatus of the present invention only needs to include an image forming unit, and may be a so-called multi function peripheral (MFP) having a function as a copying machine or a facsimile machine, or an apparatus having only a copying function.

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

  The image forming apparatus 1 transfers a toner image formed by the tandem-type image forming unit A1 that forms a toner image based on image data, a paper storage unit 2 that stores paper, and the image forming unit A1 onto the paper 2 A next transfer unit 3 is provided. The image forming apparatus further includes a fixing unit 4 that fixes the transferred toner image on the paper, a paper discharge device 5 that discharges the paper on which the fixing has been completed, and a paper discharge tray 7 that receives the discharged paper. Further, the image forming apparatus 1 includes a paper transport unit 6 that transports paper from the paper storage unit 2 to the paper discharge device 5.

  The image forming unit A1 corresponds to an intermediate transfer belt B1, which is an intermediate transfer body, an intermediate transfer belt removing unit B2, and each color of yellow (Y), cyan (C), magenta (M), and black (B). The image forming means (image forming unit) FY, FC, FM, and FB are provided. Note that the specific configuration and operation of the image forming unit A1 and the removing unit B2 therein are the same as those in the background art (see FIG. 5).

  The intermediate transfer belt B1 is a belt-like member having an endless shape, that is, a loop shape, which is wider than the maximum usable paper in a length perpendicular to the paper conveyance direction. The intermediate transfer belt B1 is driven to circulate clockwise in FIG.

The image forming units FY, FC, FM, and FB are arranged in this order in the moving direction of the intermediate transfer belt B1 and downstream of the intermediate transfer belt cleaning unit B2 and upstream of the secondary transfer unit 3. Note that the order of arrangement of the image forming units FY, FM, FC, and FB is not limited to this, but this arrangement is preferable in consideration of the influence of the color mixture on the completed image.
Next, an image forming operation of the wet image forming apparatus 1 will be described. FIG. 2 is a detailed view of one of the image forming units FY, FC, FM, and FB. The image forming units FY, FC, FM, and FB have almost the same configuration.

  The image forming unit FY includes a photosensitive drum (latent image carrier) 10, a charger 11, an LED exposure device 12, a yellow developing device HY, a primary transfer roller (voltage applying unit) 20, and a cleaning of the photosensitive drum 10. A unit 31, a static elimination device 13, and a carrier liquid removal roller (carrier removal member) 30 are provided.

  The other image forming units FM, FC, and FB include developing devices HM, HC, and HB corresponding to the respective colors. Of the image forming units, the image forming unit FB located on the most downstream side in the moving direction of the intermediate transfer belt B1 is not provided with the carrier liquid removing roller 30 because the image forming unit is not located downstream thereof. Other configurations are the same.

  The photoreceptor drum 10 only needs to be able to carry a toner image containing toner charged on its surface (charged to a positive polarity in this embodiment).

  In the present embodiment, the photosensitive drum 10 is a substantially cylindrical member that is arranged to be rotatable around a rotation axis that is perpendicular to the moving direction of the intermediate transfer belt B1 and parallel to the surface direction of the intermediate transfer belt B1. Further, the photosensitive drum 10 is in contact with the surface of the intermediate transfer belt B1 at a predetermined primary transfer position 10S. The photosensitive drum 10 can be rotated so that the moving direction at the primary transfer position 10S is the same as the moving direction of the intermediate transfer belt B1, that is, in FIG.

  The cleaning blade 35, the charge eliminating device 13, the charger 11, the LED exposure device 12, and the yellow developing device HY are arranged in this order when viewed from the primary transfer position around the photosensitive drum 10 along the rotation direction described above. Arranged.

  The charger 11 can uniformly charge the surface of the photosensitive drum 10.

  The LED exposure device 12 has an LED light source, and irradiates the charged surface of the photosensitive drum 10 with light corresponding to the image information in accordance with the image information instructed to be printed from the above-described host device. An electrostatic latent image can be formed.

  The developing device HY includes a developing container 40, a developing roller 40a, a supply roller 40b, a pumping roller 40c, stirring spirals 40d and 40e, a cleaning blade 45, and a supply roller doctor blade 40g.

The developing device HY for yellow applies toner to the electrostatic latent image by holding a developer containing yellow toner and a liquid carrier so as to face the electrostatic latent image. It can be developed as a toner image. This toner image is primarily transferred to the intermediate transfer belt B1 by the primary transfer roller 20. Details of the primary transfer roller 20 will be described later.
Next, the configuration of the developing device HY will be described. Each color developing device HY, HC, HM, HB has the same configuration.

  The developer container 40 stores therein a developer composed of yellow toner particles and a liquid carrier. The stirring spirals 40d and 40e are provided so as to be entirely immersed in the developer in the developing container 40, and stir the developer. The toner particles are uniformly dispersed in the carrier liquid by the rotation of the stirring spirals 40d and 40e.

  The pumping roller 40c is disposed so that a part of the pumping roller 40c is immersed in the developer in the developing container, and the developer is pumped up by adhering to the surface. A supply roller 40b is disposed so as to be in contact with the pumping roller 40c, and the developer is supplied from the pumping roller 40c. A supply roller doctor blade that regulates the developer layer thickness on the surface of the supply roller 40b on the downstream side of the position in contact with the pumping roller 40c in the rotational direction of the supply roller 40b and upstream of the contact position with the developing roller 40a described later 40g is provided. The supply roller doctor blade 40g regulates the developer layer thickness on the surface of the supply roller 40b to be a predetermined amount. A developing roller 40a is disposed so as to be in contact with the supply roller 40b, and a developer is applied to the surface thereof from the supply roller 40b. Since the developer layer thickness of the supply roller 40b is regulated to a predetermined value, the developer layer thickness formed on the surface of the developing roller 40a is also kept at the predetermined value. The developing roller 40a is in contact with the photosensitive drum 10, and a toner corresponding to an image instructed to be formed by the host apparatus by the potential difference between the electrostatic latent image on the surface of the photosensitive drum 10 and the developing bias applied to the developing roller 40a. An image is formed on the surface of the photosensitive drum 10 (development operation). While the developing roller 40a is being driven, liquid carrier moves from the developing roller 40a to the photosensitive drum 10 by small amounts.

  The developer on the surface of the developing roller 40a that has completed the developing operation on the photosensitive drum 10 is removed by the cleaning blade 45, flows down along the surface of the cleaning blade 45, and is stored in the developing container 40 through a flow path (not shown). Mixed with the developer.

  A toner concentration sensor 40h is disposed in the developing container, and detects the toner concentration of the developer in the developing container 40. When it is detected that the toner concentration is lower than a predetermined value, toner (developer having a toner concentration higher than the predetermined value) is supplied from a toner cartridge (not shown) to the developing container 40, and the toner concentration is higher than the predetermined value. The carrier liquid is supplied to the toner container 40 from a carrier liquid cartridge (not shown).

  Further, a developer liquid level sensor 40i is disposed in the developing container 40, and detects whether or not the developer liquid level in the developing container 40 is a predetermined value. When it is detected that the liquid level of the developer is lower than a predetermined value, the developer container 40 receives toner from a toner cartridge (not shown) and carrier liquid from a carrier liquid cartridge (not shown) via a pipe (not shown). At a predetermined ratio, and the liquid level is adjusted to a predetermined value. Note that a developer adjusting device may be provided, and the toner and the carrier liquid may be mixed at a predetermined ratio and then supplied to the developing container 40. When it is detected that the liquid level of the developer is higher than a predetermined value, the developer is discharged from a developer discharge pipe (not shown) provided in the developing container 40 and temporarily stored in a reserve tank (not shown).

  The cleaning blade 31a is a blade-like member disposed so as to be in contact with the photosensitive drum 10. The cleaning blade 31a removes the developer remaining on the surface of the photosensitive drum 10 after the primary transfer.

  The neutralization device 13 includes a light source. After the developer is removed by the cleaning blade 31a, the surface of the photosensitive drum 10 is neutralized by light from the light source to prepare for the next image formation.

  The primary transfer roller 20 is disposed so as to contact the back surface of the intermediate transfer belt B1 at a voltage application position 20S downstream from the primary transfer position 10S in the moving direction of the intermediate transfer belt B1. The primary transfer roller 20 is applied with a voltage having a polarity (minus in this embodiment) opposite to the charged polarity of the toner in the toner image from a power source (not shown). That is, the primary transfer roller 20 can apply a voltage having a polarity opposite to that of the toner to the intermediate transfer belt B1 at the voltage application position 20S. Since the intermediate transfer belt B1 has conductivity, the applied voltage attracts toner to the surface side of the intermediate transfer belt B1 at the voltage application position 20S and the periphery thereof. While the intermediate transfer belt B1 is being driven, the liquid carrier moves from the photosensitive drum 10 to the intermediate transfer belt B1 by small amounts.

  Therefore, in the present embodiment, the primary transfer position 10S is arranged within a range where toner is attracted to the intermediate transfer belt B1 side by the applied voltage. As a result, the toner moves from the photosensitive drum 10 to the surface of the intermediate transfer belt B1, and primary transfer is performed.

  As long as primary transfer is possible in this way, the specific configuration of the primary transfer roller 20 is not particularly limited, and the specific configuration can be changed as appropriate. In the present embodiment, the primary transfer roller 20 can rotate in the opposite direction to the photosensitive drum 10 around a rotational axis parallel to the rotational axis of the photosensitive drum 10, that is, the moving direction at the charge application position 20S is A substantially cylindrical member that is rotatable so as to be in the same direction as the intermediate transfer belt B1 is used.

  In this embodiment, the carrier removal roller 30 is a substantially cylindrical member that can rotate in the same direction as the photosensitive drum 10 around a rotational axis that is parallel to the rotational axis of the photosensitive drum 10. There is no limitation, and in the moving direction of the intermediate transfer belt B1, it is downstream of the primary transfer position 10S and upstream of the secondary transfer position (the photosensitive drum 10 of the downstream image forming unit and the intermediate transfer belt B1 are It suffices if the carrier can be removed from the surface of the intermediate transfer belt B1 at a position upstream of the contact position. Specifically, the carrier removal roller 30 only needs to be able to move the carrier on the surface of the intermediate transfer belt B1 to its own surface by contacting the surface of the intermediate transfer belt B1.

  As described above, the carrier is also transferred little by little from the photosensitive drum 10 to the intermediate transfer belt B1. This carrier transfer may interfere with the primary transfer in the downstream image forming unit and cause image defects such as blurring and blurring of the image. By providing the carrier removal roller 30, it is possible to prevent such an image defect. Here, since the toner is charged only when the toner is dispersed in the carrier, the primary transfer is not satisfactorily performed if the carrier adhering to the intermediate transfer belt B1 is completely removed. For this reason, it is desirable to set so as to remove only the excess carrier while leaving the amount necessary for the primary transfer.

  In the present embodiment, the carrier removal roller 30 is incorporated in the cleaning unit 31 together with the cleaning blade 35 described above. The cleaning unit 31 is provided in the image forming unit FY. In addition to the cleaning blade 31a and the carrier removing roller 30, the cleaning unit 31 contacts the surface of the carrier removing roller 30 to remove the carrier attached to the surface of the carrier removing roller 30. The carrier removal blade 31b, the carrier removed from the carrier removal roller 30, and the developer (including toner and carrier) removed from the surface of the photosensitive drum 10 by the cleaning blade 35 are conveyed to the outside of the cleaning unit 31. A transport member 31c is provided. The image forming unit FY may further include a separation unit that separates the carrier and the toner in order to reuse the carrier and the toner conveyed by the conveyance member 31c.

  Under such a configuration, the image forming apparatus 1 that has received an instruction to form an image from a host device such as a personal computer (PC) sends the toner images of each color corresponding to the received image data to the image forming units FY, FC. , FM and FB are used. The toner image formed in each image forming unit is transferred to the intermediate transfer belt B1, and is superimposed on the intermediate transfer belt B1 to form a color toner image.

  In synchronism with the formation of the color toner image, the paper stored in the paper storage unit 2 is taken out from the paper storage unit 2 one by one by a paper feeding device (not shown) and transported on the paper transport unit 6. Then, the sheet is sent to the secondary transfer unit 3 in synchronization with the primary transfer to the intermediate transfer belt B1, and the color toner image on the intermediate transfer belt B1 is secondarily transferred to the sheet by the secondary transfer unit 3. . The sheet on which the color toner image has been transferred is further conveyed to the fixing unit 4 where the color toner image is fixed on the sheet by heat and pressure. Further, the paper is discharged by a paper discharge device 5 to a paper discharge tray portion 7 provided on the outer periphery of the image forming apparatus 1. After the secondary transfer, the toner remaining on the intermediate transfer belt B1 is removed from the intermediate transfer belt B1 by the intermediate transfer belt removing means B2. When the intermediate transfer belt B1 stops and, for example, about 1 hour elapses, the developer C that has been scraped and collected above the removal blade B3 is removed beyond both sides in the longitudinal direction of the removal blade B3 by capillary action. It also wraps around the back side of the blade B3 and adheres to the downstream side of the removal blade of the intermediate transfer belt B1. The time from when the intermediate transfer belt B1 stops until the above phenomenon occurs depends on the type of carrier, the amount of toner in the developer C, environmental conditions such as temperature and humidity, and the like.

  FIG. 3 is a hardware configuration diagram of the image forming apparatus 1 in the present embodiment.

  The image forming apparatus 1 includes a CPU (Central Processing Unit) 201, a RAM (Random Access Memory) 202, a ROM (Read On 7 Memory) 203, an HDD (Hard Disk Drive) 204, and a driver 205 corresponding to each driving unit in the printing. They are connected via an internal bus 206. The CPU 201 uses, for example, the RAM 202 as a work area, executes a program stored in the ROM 203, the HDD 204, etc., and transmits and receives data and commands to and from the driver 205 based on the execution result, as shown in FIG. The operation of each driving unit is controlled. Further, each means (shown in FIG. 4) described later other than the drive unit also operates as each means when the CPU 201 executes the program.

FIG. 4 is a software configuration diagram of the image forming apparatus 1 in the present embodiment.
The user inputs an image formation instruction from the touch panel 401 of the image forming apparatus 1 or from the personal computer 501 connected to the image forming apparatus 1 via a network. Once this image formation is completed and the intermediate transfer belt B1 is stopped, if there is no instruction for image formation for a predetermined time (for example, 20 minutes) or longer, the separating means A 402 drives the position moving means J1 such as a hydraulic jack. Thus, the intermediate transfer belt B1 and the secondary transfer means (more specifically, the secondary transfer roller) 62 of the secondary transfer unit 3 are separated from each other. Further, almost simultaneously, the separation unit B404 drives the position shifting unit J2 such as the eccentric cam driving unit contacting the image forming units FY, FC, FM, and FB, for example, so that the image forming units FY, FC, , FM, and FB are separated from the intermediate transfer belt B1. By separating these image forming units from the intermediate transfer belt B1, the photosensitive drum 10 included in these image forming units is separated from the intermediate transfer belt B1. However, since the primary transfer roller 20 is in contact with the back surface of the intermediate transfer belt B1, it is not necessary to move it.

  If there is no instruction for image formation for a predetermined time or longer after the intermediate transfer belt B1 is stopped, the reason for performing the separation operation as described above is that the photosensitive drum 10 and the secondary transfer means 62 are in a state where the intermediate transfer belt B1 is stopped. For example, if the contact is caused by pressure, the characteristics of the contact portion of the intermediate transfer belt B1 change, which hinders the next image formation. If there is no hindrance, they may be separated immediately before the intermediate transfer belt B1 is next driven.

Next, when the user instructs to form an image again from the touch panel 401 or from the personal computer 501 connected to the image forming apparatus 1 via a network, between the removal unit B2 and the secondary transfer unit 62 from the start of the image formation. After the time required for the intermediate transfer belt B1 to move (hereinafter referred to as “movement time A”), the contact means A403 makes the intermediate transfer belt B1 and the secondary transfer means 62 contact each other. This contact is also performed by driving the position moving means J1.
That is, after waiting for the developer C to pass the secondary transfer position on the intermediate transfer belt B1, the secondary transfer means (more specifically, the secondary transfer roller) 62 is brought into contact with the intermediate transfer belt B1. is there. As a result, the developer C is prevented from adhering to the secondary transfer means 62, and deterioration of image quality can be prevented. The developer C that has passed through the secondary transfer unit 62 is removed when it passes through the removing unit B2 again, and thereafter normal image formation is performed. The moving time A is calculated by dividing the distance between the removing unit B2 and the secondary transfer unit 62 by the linear speed of the intermediate transfer belt B1, and is stored in the RAM 202 in advance.

  Further, when the contact means B406 drives the position movement means J2, the separated image forming units FY, FC, FM, and FB are simultaneously applied to the intermediate transfer belt B1 by the contact of the secondary transfer means 62. Abut. By bringing these image forming units into contact with the intermediate transfer belt B1, the photosensitive drum 10 included in these image forming units is brought into contact with the intermediate transfer belt B1. Note that the image forming units FY, FC, FM, and FB contact the intermediate transfer belt B1 after a minimum time has elapsed.

  That is, the time required for the developer C to pass through the position where the photosensitive drum 10 included in the image forming units FY, FC, FM, and FB should contact the intermediate transfer belt B1 (hereinafter referred to as “movement time B”). 2), the image forming units FY, FC, FM, and FB are brought into contact with the intermediate transfer belt B1. As a result, the developer C is transferred to the photosensitive drum 10 and the intermediate transfer belt B1 shown in FIG. This solves the problem that primary transfer cannot be performed sufficiently because the amount of carrier liquid in the contact nip is excessive and the primary transfer cannot be performed sufficiently. Similarly to the movement time A described above, the movement time B is also an intermediate distance between the removal means B2 and the contact position between the photosensitive drum 10 of the image forming units FY, FC, FM, and FB and the intermediate transfer belt B1. It is calculated by dividing by the linear velocity of the transfer belt B1, and stored in the RAM 202 in advance.

  Here, four types of movement time B may be calculated for each of the image forming units FY, FC, FM, and FB in consideration of the difference in the positions of the image forming units FY, FM, FC, and FB. For example, it is assumed that the moving time B is TM for the magenta image forming unit FM. The image forming unit FM is separated from the intermediate transfer belt B1 during the movement time B (TM) from the start of the image formation. After the movement time B (TM) has elapsed, the intermediate transfer belt B1 and the image forming unit are separated. You can abut FM.

  Further, during the movement time A, the acceleration unit 405 increases the rotational speed of the intermediate transfer driving roller 63a, thereby accelerating the linear speed of the intermediate transfer belt B1 from the time of image formation. In other words, the stain portion can be quickly passed through the secondary transfer means 62, so that the waiting time until the start of printing can be shortened. In this case, each moving time according to the linear velocity by the acceleration means 405 is calculated. In addition, the image forming units FY, FC, FM, and FB are separated and brought into contact with the intermediate transfer belt B1, but only the photosensitive drum 10 of the image forming unit is separated and brought into contact with the intermediate transfer belt B1. You may contact | abut.

  When the secondary transfer unit 62 and the image forming units FY, FC, FM, and FB are brought into contact with the intermediate transfer belt B1 while the intermediate transfer belt B1 is being driven, the impact is affected by the drive of the intermediate transfer belt B1. Deterioration is promoted. Further, in order to prevent the toner from moving, the photosensitive drum 10 of the image forming units FY, FC, FM, and FB and the intermediate transfer belt B1 are brought into contact with each other in a state where a voltage is applied. At this time, the photoreceptor drum 10 may be deteriorated due to leakage or the like. If it is necessary to prevent this, the intermediate transfer belt B1 is stopped after the second movement time has elapsed, and then the secondary transfer means 62 and the image forming units FY, FC, FM, and FB are brought into contact with the intermediate transfer belt B1. Then, the intermediate transfer belt B1 is driven again.

  As described above, high-quality image formation can be continuously performed. In the present embodiment, the intermediate transfer member is described as the intermediate transfer belt B1, but this is only an example, and even when another intermediate transfer member (for example, an intermediate transfer drum) is used, There is application of the invention. Further, as described above, developer infiltration tends to occur when a liquid developer is used. Therefore, the present invention is particularly effective in a wet image forming apparatus using a liquid developer.

  The image forming apparatus according to the present invention controls high-quality image formation by controlling the influence of the developer adhering to the intermediate transfer belt on the downstream side of the removing unit from appearing on the image when the intermediate transfer belt is stopped. Is possible. Therefore, it is useful as a printer, a copier, a multi-function machine, or the like that supports high-quality printing.

1 is a schematic configuration diagram of an image forming apparatus of the present invention. 2 is a detailed view of an image forming unit in the image forming apparatus of the present invention. FIG. 1 is a hardware configuration diagram of an image forming apparatus of the present invention. 2 is a software configuration diagram of the image forming apparatus of the present invention. FIG. 1 is a schematic configuration diagram of a printing mechanism in a wet image forming apparatus.

Explanation of symbols

1 Image forming device
A1 Image forming unit
B1 Intermediate transfer belt
B2 removal means
B3 removal blade
B4 removal roller
2 Paper compartment
3 Secondary transfer section 3
4 Fixing part
5 Output device 5
6 Paper transport section
7 Output tray
FY, FM, FC, FB Image forming unit
HY, HM, HC, HB development equipment
10 Photosensitive drum
40 Developer container
40a Developing roller
201 CPU
202 RAM
203 ROM
204 HDD
205 drivers
206 Internal bus
401 touch panel
402 Separation means A
403 Contact means A
404 Separation means B
405 Acceleration means
406 Contact means B
J1, J2 position moving means
62 Secondary transfer means
63a Intermediate transfer drive roller
63b Intermediate transfer tension roller
63c Intermediate transfer driven roller

Claims (3)

Primary transfer means for primarily transferring the toner image formed on the latent image carrier to the intermediate transfer member;
Secondary transfer means for transferring the toner image from the intermediate transfer member to a recording medium;
Removing means for removing the residual developer from the intermediate transfer member;
A separation means A for separating the intermediate transfer body and the secondary transfer means after driving of the intermediate transfer body is stopped;
Separation means B for separating the intermediate transfer member and the latent image carrier after driving of the intermediate transfer member is stopped ,
After the start of driving of the intermediate transfer member, after the elapse of a movement time A required for the intermediate transfer member to move between the removing unit and the secondary transfer unit, the intermediate transfer member and the secondary transfer unit are contacted. Contact means A to be contacted;
An image forming apparatus comprising: an accelerating unit that sets a linear velocity of the intermediate transfer member to be higher than a linear velocity at the time of image formation from the start of driving of the intermediate transfer member to the elapse of the movement time A. Further, after the elapse of a movement time B required for the intermediate transfer member to move between the removing means and the latent image carrier from the start of driving of the intermediate transfer member, the intermediate transfer member, the latent image carrier, 2. The image forming apparatus according to claim 1, further comprising a contact means B that contacts the image forming apparatus. The primary transfer means is
The image forming apparatus according to claim 1 or 2 for forming the toner image with a liquid developer comprising a toner and a liquid carrier.

Images