JP4910659B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multi-function machine combining two or more of these.

  As a typical image forming apparatus such as a copying machine, a printer, a facsimile machine, or a combination machine combining two or more of these, an image carrier on which a toner image is formed, and an image carrier that is in pressure contact with the image carrier There is an image forming apparatus including a transfer member that forms a nip portion with an image carrier and passes a recording medium through the nip portion to transfer a toner image on the image carrier to the recording medium.

  In this type of image forming apparatus, in order to suppress clogging of the recording medium and image rubbing due to contact with other parts of the unfixed toner image, the recording medium discharged from the nip portion is the next processing unit (usually a toner). To remove the recording medium from the image carrier when it is attached to the charge-removing member or the image carrier for separating the recording medium from the image carrier so as to go as smoothly as possible to a fixing device for fixing the image to the recording medium) It has been proposed to provide a separate nail.

  However, a situation in which the separation property of the recording medium from the image carrier is not sufficient only by providing the charge eliminating member and the separation claw may occur.

  For this reason, it has also been proposed to improve the separation from the image carrier by blowing air from the image carrier side to the recording medium discharged from the nip portion between the image carrier and the transfer member. Such air blowing is described in many documents such as Japanese Patent Application Laid-Open Nos. 2006-18074, 2003-195586, and 59-40672.

JP 2006-18074 A JP 2003-195586 A JP 59-40672 A

  However, according to the separation method in which air is blown from the image carrier side to the recording medium discharged from the nip portion between the image carrier and the transfer member, the separation from the image carrier is improved. Since air is blown toward the surface onto which the toner image has been transferred, the unfixed toner image may be disturbed and image defects may occur.

  Therefore, the present invention provides an image carrier on which a toner image is formed and a nip portion formed between the image carrier and the image carrier, and a recording medium is passed through the nip portion to pass the image. An image forming apparatus including a transfer member for transferring a toner image on a carrier to the recording medium, wherein the separation property of the recording medium discharged from the nip portion from the image carrier is determined for the unfixed toner image. It is an object of the present invention to provide an image forming apparatus that can be improved without causing disturbance.

In order to solve the above problems, the present invention provides:
An image carrier on which a toner image is formed;
A transfer member that is pressed against the image carrier to form a nip portion with the image carrier, and passes a recording medium through the nip portion to transfer a toner image on the image carrier to the recording medium; An image forming apparatus including
A transfer member holder that covers the transfer member in a region downstream of the nip portion in the recording medium conveyance direction and holds the transfer member;
An outer shell member that covers the transfer member holder at a distance from the side opposite to the transfer member and has a recording medium guide portion on the downstream side of the transfer member holder in the recording medium conveyance direction;
An air intake device connected to the outer shell member behind the outer shell member on the side opposite to the transfer member;
The outer shell member is formed with a vent for communicating a space between the outer shell member and the transfer member holder to the intake device,
The recording medium guide portion is disposed so as to provide an air inlet between the transfer member holder and the end portion on the image carrier side of the transfer member holder,
The recording medium that is sucked from the suction port by the suction device through the air gap through the space between the outer shell member and the transfer member holder and discharged from the nip portion to the transfer member holder side. An image forming apparatus capable of applying a suction force is provided.

  The image forming apparatus according to the present invention may be a monochrome image forming apparatus or a color image forming apparatus. In addition, whether it is a monochrome image forming apparatus or a color image forming apparatus, the toner image formed on the image carrier from the electrostatic latent image carrier such as a photoreceptor is directly transferred to a recording medium and fixed. Even in the apparatus, a toner image is primarily transferred from an electrostatic latent image carrier such as a photosensitive member onto an intermediate transfer member (one type of image carrier) such as an intermediate transfer belt, and then primary transferred from the intermediate transfer member to a recording medium. An image forming apparatus that secondarily transfers and fixes the toner image may be used.

  The “image carrier on which a toner image is formed” in the image forming apparatus according to the present invention is an image carrier from which a toner image is transferred onto a recording medium by a transfer member. For example, in an image forming apparatus for transferring and fixing a toner image directly from an image carrier such as a photoconductor to a recording medium, the image carrier such as the photoconductor is an electrostatic latent image carrier such as a photoconductor. In an image forming apparatus in which a toner image is primarily transferred onto an intermediate transfer member such as an intermediate transfer belt and the primary transfer toner image is secondarily transferred from the intermediate transfer member to a recording medium and fixed. Is the body.

  As the “transfer member” in the image forming apparatus according to the present invention, a transfer roller can be raised as a representative example, but an endless transfer belt wound around a plurality of pulleys may be used.

  In any case, according to the image forming apparatus of the present invention, the recording medium (recording paper or the like) discharged from the nip portion between the image carrier and the transfer member is transferred to the recording medium separation region that separates the image carrier from the image carrier. An air inlet provided between the image carrier side end of the member holder and the recording medium guide portion of the outer shell member covering the transfer member holder faces.

  Then, by operating the air intake device connected to the back of the outer shell member, air can be sucked from the air inlet through the space between the outer shell member and the transfer member holder and the vent of the outer shell member. As a result, the recording medium is separated from the image carrier by applying a suction force to the surface of the recording medium opposite to the toner image transfer surface without disturbing the unfixed transfer toner image, and upstream of the recording medium guide section. Can be drawn toward the transfer member holder located on the side, and can be smoothly and smoothly conveyed to the next processing section (usually a fixing device) by the recording medium guide section.

  In the image forming apparatus according to the present invention, in order to further improve the separation of the recording medium from the image carrier by sucking stronger from the air inlet, in the space between the outer shell member and the transfer member holder, In addition, at least in the state where the transfer member is in pressure contact with the image carrier on the downstream side of the vent of the outer shell member in the direction of the intake flow by the intake device in the space, the intake flow is directed to the vent. You may arrange | position the ventilation blocker which fills this space so that it may face.

  The transfer member holder may be a movable holder that can press and separate the transfer member from the image carrier. For example, the transfer member holder can be a holder that is driven to swing around a fulcrum on the outer shell member. More specifically, the transfer member is pressed against the image carrier by being supported by an arm swingable about an axis provided on the outer shell member, and the arm is driven to swing by a drive unit such as a solenoid. Examples thereof can be separated from the image carrier.

  When the transfer member holder is a movable holder, it is considered that the space size between the holder and the outer shell member varies with the movement of the holder. Therefore, when the ventilation blocking member is employed, the ventilation blocking member is used. A member that can be expanded and contracted to fill the space between the outer shell member and the transfer member holder (in other words, can be expanded by compression and elastic return) regardless of the variation in the space size due to the pressure contact and separation of the transfer member with respect to the image carrier. It is good.

  Further, when the transfer member holder is a movable holder and the air blocking member is employed, the air blocking member is attached to one of the transfer member holder and the outer shell member, and slides to the other side at a portion facing the other. A contactable film may be attached.

  In order to further improve the separation of the recording medium from the image carrier, an air inlet may be formed in the recording medium guide portion of the outer shell member and the recording medium guide portion air inlet may be communicated with the air intake device.

  The recording medium guide portion of the outer shell member includes a metal guide plate for the recording medium guide and a mounting portion for the metal guide plate in order to improve wear resistance and slidability with the recording medium. The recording medium guide portion air inlet may be formed by an opening portion formed in the metal guide plate and an opening portion formed in the metal guide plate attachment portion corresponding to the opening portion.

  For smooth conveyance of the recording medium, the end of the recording medium guide portion on the recording medium entry side is at least in the state where the transfer member is pressed against the image carrier and the nip portion outlet and the transfer medium. You may make it not protrude to the image carrier side from the linear extension line which connects the edge by the side of the image carrier of a member holder.

  The intake device may include an intake duct that communicates with a vent of the outer shell member. In this case, the intake duct may be formed integrally with the outer shell member. An intake fan can be attached to the intake duct.

An image forming apparatus according to the present invention includes a charge removal member for removing electricity from the recording medium discharged from the nip portion, and a recording medium that comes out of the nip portion and remains attached to the image carrier. You may have the separation nail etc. for peeling from.
When providing a static eliminating member, it may be provided at the end of the transfer member holder on the image carrier side.

  As described above, according to the present invention, an image carrier on which a toner image is formed and a nip portion are formed between the image carrier and the image carrier, and a recording medium is placed in the nip portion. An image forming apparatus including a transfer member that passes and transfers a toner image on the image carrier to the recording medium, wherein the separation property of the recording medium discharged from the nip portion from the image carrier is It is possible to provide an image forming apparatus that can be improved without causing disturbance of an unfixed toner image.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an example A of an image forming apparatus according to the present invention.

  The image forming apparatus A is a tandem type full color printer. The printer A includes a driving roller 21, a roller 22 facing the driving roller 21, a roller 21a below the driving roller, and an endless intermediate transfer belt 2 wound around the roller 22a below the opposing roller. The transfer belt 2 can be rotated counterclockwise in the figure (arrow direction in the figure) by a driving roller 21 driven by a belt driving unit (not shown).

  A cleaning device 8 that removes and cleans secondary transfer residual toner and the like on the transfer belt 2 with a cleaning blade faces the transfer belt portion on the roller 22a.

The secondary transfer roller 3 faces the transfer belt portion on the driving roller 21.
The transfer roller 3 can be pressed against and separated from the intermediate transfer belt 2 by an arm driving unit 37 (see FIGS. 2 and 3) described later. The surface layer portion of the secondary transfer roller 3 is formed of an elastic material, and a nip portion N is formed between the secondary transfer roller 3 and the intermediate transfer belt 2 when pressed against the transfer belt 2, and is driven by the rotation of the intermediate transfer belt 2. Alternatively, as will be described later, the recording medium 50 is rotated following the movement of the recording medium 50 fed into the nip portion. A secondary transfer bias can be applied to the secondary transfer roller 3 from a secondary transfer bias power supply device (not shown).

  A timing roller pair 4 is disposed below the secondary transfer roller 3, and a recording medium storage cassette 5 that stores a recording medium 50 is detachably mounted below the pair of timing rollers 4. The recording medium 50 accommodated in the cassette 5 can be pulled out one by one by the medium supply roller 51 and supplied to the timing roller pair 4. As the recording medium 50, a recording sheet, an overhead projector sheet, or the like can be used.

A fixing device 6 is disposed above the transfer roller 3.
The fixing device 6 includes a heated fixing roller 61 and a pressure roller 62 pressed against the fixing roller 61.
A medium discharge roller pair 71 and a medium discharge tray 7 are provided on the downstream side of the fixing device 6 in the recording medium conveyance direction.

  Between the rollers 21a and 22a around which the intermediate transfer belt 2 is wound, the yellow image forming unit Y, the magenta image forming unit M, the cyan image forming unit C, and the rollers 22a to 21a along the transfer belt 2 Black image forming portions K are arranged in this order.

  Each of the image forming units Y, M, C, and K includes a drum-type photoconductor 11 as an electrostatic latent image carrier, and a charger 12, an image exposure device 13, and a developer 14 are provided around the photoconductor. A primary transfer roller 15, a leaning device 16 that removes and cleans the primary transfer residual toner on the photosensitive member, a light neutralizing device 17, and the like are arranged in this order.

  The photoreceptor 11, the charger 12, the developing device 14, the cleaning device 16, and the light neutralizing device 17 in each image forming unit are provided in a cartridge case, and form a process cartridge together with the cartridge case. That is, the yellow process cartridge YC for forming the yellow image forming portion Y, the magenta process cartridge MC for forming the magenta image forming portion M, the cyan process cartridge CC for forming the cyan image forming portion C, and the black image forming This is a black process cartridge KC for forming the portion K.

As shown in FIG. 1, the primary transfer roller 15 of each image forming unit faces the photoconductor 11 with the transfer belt 2 in between, and is rotated by the running of the belt. A primary transfer bias for primary transfer of a toner image formed on the photoreceptor 11 to the belt 2 can be applied to the primary transfer roller 15 from a primary transfer bias power supply device (not shown).
The exposure device 13 performs image exposure on the photoconductor 11 using a laser beam in accordance with image information provided from a personal computer (not shown) or the like.

The photoconductor 11 in each image forming unit is a negatively chargeable photoconductor here, and is rotated clockwise in the drawing by a photoconductor drive motor (not shown).
A voltage for charging the photosensitive member is applied to the charger 12 in each image forming unit at a predetermined timing from a charging power supply (not shown).

  The developing unit 14 in each image forming unit employs a negatively chargeable toner in this example, and an electrostatic latent image formed on the photoconductor 11 is developed from a developing bias applying power supply device (not shown) to a developing bias voltage. Can be reversely developed by the developing roller 141 to which is applied.

  A cleaning device 16 in each image forming unit removes and cleans primary transfer residual toner and the like on the photosensitive member 11 with a cleaning blade.

Here, image formation by the printer A will be described.
The printer A can form an image using at least one of the image forming units Y, M, C, and K. Taking a case where a full color image is formed using all of the image forming portions Y, M, C, and K as an example, first, a yellow toner image is formed in the yellow image forming portion Y, and this is formed on the transfer belt 2 as a primary. Transcript.

  That is, in the yellow image forming portion Y, the photosensitive member 11 is rotationally driven in the clockwise direction in the figure, and the surface is uniformly charged to a predetermined potential by the charger 12, and the yellow image is transferred from the image exposure device 13 to the charged area. Image exposure is performed, and an electrostatic latent image for yellow is formed on the photoreceptor 11. The electrostatic latent image is developed by a developing roller 141 to which a developing bias of a developing unit 14 having yellow toner is applied to become a visible yellow toner image, and the toner image is transferred onto the transfer belt 2 by a primary transfer roller 15. Primary transfer is performed. At this time, a primary transfer bias voltage is applied to the primary transfer roller 15 from a power supply device (not shown).

  Similarly, a magenta toner image is formed in the magenta image forming unit M and transferred to the transfer belt 2, a cyan toner image is formed in the cyan image forming unit C and transferred to the transfer belt 2, and in the black image forming unit K. A black toner image is formed and transferred to the transfer belt 2.

Yellow, magenta, cyan, and black toner images are formed at the timing when these toner images are transferred onto the intermediate transfer belt 2 in an overlapping manner.
Thus, the multiple toner image formed on the transfer belt 2 moves toward the secondary transfer roller 3 by the rotation of the transfer belt 2.

  On the other hand, the recording medium 50 is pulled out from the cassette 5 by the medium supply roller 51, supplied to the timing roller pair 4, and is on standby.

  The recording medium S waiting at the timing roller pair 4 is aligned with the nip portion N between the transfer belt 2 and the secondary transfer roller 3 pressed against the multiple toner images sent by the intermediate transfer belt 2. The multiple toner image is secondarily transferred onto the recording medium 50 by the secondary transfer roller 3 to which a secondary transfer bias is applied from a power supply device (not shown).

  Thereafter, the recording medium 50 is passed through the fixing device 6 where the multiple toner images are fixed on the recording medium 50 under heat and pressure. The recording medium 50 is continuously discharged to the discharge tray 7 by the medium discharge roller pair 71 and the like.

  In each image forming unit, the toner remaining on the photoreceptor 11 after the primary transfer of the toner image is removed and cleaned by the cleaning device 16, and the residual charge is erased by the photostatic device 17. Further, the secondary transfer residual toner and the like on the intermediate transfer belt 2 are removed and cleaned by the cleaning device 8.

Next, the structure around the secondary transfer roller 3 will be further described.
Although not shown in FIG. 1, as shown in FIGS. 2 and 3, the secondary transfer roller 3 is located in a downstream region in the recording medium conveyance direction from the nip portion N between the intermediate transfer belt 2 and the roller 3. A transfer roller holder 31 covering the circumferential surface of the roller 3 is rotatably supported.
The transfer roller 3 and the holder 31 are covered with an outer shell member 33 from the side opposite to the transfer belt 2.

  A fulcrum shaft 33 s is provided at each of the front side and the back side of the upper end portion of the outer shell member 33. An upper end 361 of an arm 36 is rotatably fitted to each shaft 33s. A shaft 311 protruding from the transfer roller holder 31 is supported on the lower end portion 362 of each arm 36. The center axis of the protruding shaft 311 of the holder 31 and the rotation center axis of the transfer roller 3 coincide.

  The outer shell member 33 is equipped with an arm drive unit 37 using a solenoid. When the toner image on the transfer belt 2 is secondarily transferred to the recording medium 50, the arm 36 is swung by the drive unit and transferred. The roller 3 can be brought into pressure contact with the intermediate transfer belt 2 and can be separated from the pressure contact state.

  A discharge member (discharge cloth here) 32 is attached to the outer peripheral surface of the transfer roller holder 31 on the transfer belt 2 side. The neutralizing member 32 neutralizes the recording medium 50 discharged from the nip portion N to improve the separation of the recording medium 50 from the transfer belt 2 and to smoothly convey the recording medium 50 to the fixing device 6. Is for. Although the static elimination member 32 is grounded in this example, it may be connected to a power source that applies a static elimination voltage.

  As described above, the transfer roller 3 and the holder 31 are covered with the outer shell member 33 from the side opposite to the transfer belt 2. The outer shell member 33 is located at a distance from the holder 31, and a space (intake passage) 30 is formed between the outer shell member 33 and the holder 31.

  The outer shell member 33 has a recording medium guide portion 33g located slightly above the end of the transfer roller holder 31 on the transfer belt 2 side. The guide portion 33g includes a metal recording medium guide plate 331 and a portion 332 of the outer shell member body to which the guide plate 331 is attached.

  On the opposite side of the guide portion 33g, a separation claw 38 is provided for peeling from the belt 2 a recording medium that comes out of the nip portion N and can be transferred together with the transfer belt 2 while being stuck to the transfer belt 2.

  A vent H is formed in a portion of the outer shell member 33 facing the transfer roller holder 31. As shown in FIG. 3, a plurality of vent holes H are formed, each having the same size or different sizes.

  An intake device 300 is connected to the outer shell member 33. The intake device 300 includes a ventilation duct 34 formed integrally with the outer shell member 33 and an intake fan 35 attached to the duct. The vent H of the outer shell member 33 communicates the space (intake passage) 30 between the outer shell member 33 and the holder 31 to the duct 34.

An air inlet h leading to the space 30 is provided between a lower end portion of the recording medium guide portion 33g of the outer shell member 33 (here, a lower end portion of the guide plate 331) and an end portion of the transfer roller holder 31 on the transfer belt 2 side. Has been.
Therefore, by operating the intake fan 35 of the intake device 300, it is possible to intake air from the intake port h → the space 30 → the vent hole H of the outer shell member 33 → the duct 34 of the intake device 300 → the fan 35.

  By this suction, the recording medium 50 discharged from the nip N between the belt 2 and the transfer roller 3 is drawn toward the transfer roller holder 31 so as to be separated from the transfer belt 2, and from the recording medium by the charge removing member 32. Sufficient charge removal is possible, and the subsequent transfer of the recording medium to the fixing device 6 can be smoothed. In addition, since the suction is performed on the surface of the recording medium 50 opposite to the surface on which the unfixed toner image is held, the recording medium 50 is drawn toward the holder 31 in a state where the disturbance of the unfixed toner image is suppressed. be able to.

  Here, the intake air is concentrated in the order of the intake port h → the space 30 → the vent port H → the duct 34, whereby strong intake is performed from the intake port h, and the recording medium is more reliably moved to the holder 31 side (therefore, charge removal). A ventilation blocking member S is arranged on the downstream side of the ventilation hole H in the direction of the intake air flow in the space 30 so as to be pulled toward the member 32 side.

  The air-blocking member S is made of an elastic material that can be expanded and contracted, and more specifically, it is made of an elastic material that can be compressed and expanded by an elastic restoring force by releasing or loosening an external force (in this example, a urethane foam material). Attached to the transfer roller holder 31, the space 30 is filled.

  The air blocking member S may fill the space 30 with at least the transfer roller 3 being in pressure contact with the belt 2, but here the space 30 is filled both in the pressure contact state of the transfer roller 3 with respect to the belt 2 and in the separated state. Even if the transfer roller holder 3 moves as the transfer roller 3 is pressed against and separated from the belt 2, the slidability between the air blocking member S and the inner surface of the outer shell member 33 is kept good and the air blocking member S is protected. Therefore, a film f (polyethylene terephthalate film in this example) that can be slidably contacted is attached to a portion of the ventilation block member S that faces the inner surface of the outer shell member 33.

  Note that at least the transfer roller 3 is in pressure contact with the transfer belt 2 so that the transfer of the recording medium 50 discharged from the nip N to the fixing device 6 is not hindered, and the exit of the nip N and the transfer roller Recording to the belt 2 side from a linear extension line L (in other words, the surface including the exit line of the nip portion N and the edge of the transfer roller holder 31 on the belt 2 side) connecting the end of the holder 31 on the belt 2 side. The end of the medium guide portion 33g on the recording medium entry side (the lower end portion of the guide plate 331 in FIG. 2) is prevented from projecting.

  In the printer A, the recording medium 50 discharged from the nip portion N is more surely drawn to the recording medium guide portion 33g and more smoothly transferred to the fixing device 6, so that the recording medium guide portion 33g Also, an intake port communicating with the duct 34 of the intake device 300 is formed.

  The recording medium guide portion 33g has an intake port, an intake port h1 provided in the recording medium guide plate 331, and an intake port h2 formed in the main body portion 332 of the outer shell member 33 to which the guide plate 331 is attached (the intake port overlapping the intake port h1) h2). As shown in FIG. 3, a plurality of intake ports h1 and h2 are formed, and some of them have the same size or different sizes, but here they are collectively referred to as intake ports h1 and h2.

  Although the tandem type color image forming apparatus has been described above, the present invention can be applied to other types of color image forming apparatuses and also to monochrome image forming apparatuses.

  The present invention improves the separability of a recording medium discharged from the nip portion between an image carrier and a transfer member pressed against the image carrier from the image carrier without causing disturbance of an unfixed toner image. The present invention can be used to provide an image forming apparatus capable of performing the above.

1 is a diagram schematically illustrating a printer that is an example of an image forming apparatus according to the present invention. It is a figure which shows a part of structure around a transfer roller in cross section. FIG. 6 is a diagram of a structure around a transfer roller as viewed from the transfer belt side.

Explanation of symbols

A Printer Y Yellow image forming unit M Magenta image forming unit C Cyan image forming unit K Black image forming unit YC, MC, CC, KC Process cartridge 11 Photoconductor 12 Charger 13 Image exposure device 14 Developer 141 Developer roller 15 Primary Transfer roller 16 Cleaning device 17 Light neutralization device 21 Drive roller 22 Opposing rollers 21a, 22a Roller 2 Intermediate transfer belt 3 Secondary transfer roller 31 Transfer roller holder 311 Projection shaft 32 of the transfer roller holder Static neutralization member 33 Outer shell member H Vent 30 Space (intake passage)
S air blocking member f slidable contactable film 33g recording medium guide portion h air inlet 331 recording medium guide plate h1 air inlet 332 portion of outer shell member main body h2 air inlet 300 air intake device 34 air duct 35 air intake fan 33s fulcrum shaft 36 arm 361 Arm upper end portion 362 Arm lower end portion 37 Arm drive portion 38 Separation claw D Holder rotation drive portion N Nip portion 4 between belt 2 and roller 3 Timing roller pair 5 Recording medium storage cassette 51 Medium drawing roller 50 Recording medium 6 Fixing device 61 Fixing Roller 62 Pressure roller 71 Medium discharge roller pair 7 Medium discharge tray 8 Cleaning device

Claims (11)

An image carrier on which a toner image is formed;
A transfer member that is pressed against the image carrier to form a nip portion with the image carrier, and passes a recording medium through the nip portion to transfer a toner image on the image carrier to the recording medium; An image forming apparatus including
A transfer member holder that covers the transfer member in a region downstream of the nip portion in the recording medium conveyance direction and holds the transfer member;
An outer shell member that covers the transfer member holder at a distance from the side opposite to the transfer member and has a recording medium guide portion on the downstream side of the transfer member holder in the recording medium conveyance direction;
An air intake device connected to the outer shell member behind the outer shell member on the side opposite to the transfer member;
The outer shell member is formed with a vent for communicating a space between the outer shell member and the transfer member holder to the intake device,
The recording medium guide portion is disposed so as to provide an air inlet between the transfer member holder and the end portion on the image carrier side of the transfer member holder,
The recording medium that is sucked from the suction port by the suction device through the air gap through the space between the outer shell member and the transfer member holder and discharged from the nip portion to the transfer member holder side. An image forming apparatus capable of applying a suction force.   In the space between the outer shell member and the transfer member holder, and in the direction of the intake air flow by the intake device in the space, the transfer member is at least on the image carrier on the downstream side of the vent of the outer shell member. The image forming apparatus according to claim 1, wherein a ventilation blocking member is disposed to fill the space so as to direct the intake air flow toward the ventilation port in a state of being pressed.   The transfer member holder is a movable holder capable of press-separating the transfer member with respect to the image carrier, and the ventilation blocking member is independent of the variation in the space size due to the press-separation of the transfer member with respect to the image carrier. The image forming apparatus according to claim 2, wherein the image forming apparatus is an extendable member that fills a space between an outer shell member and the transfer member holder.   The image according to claim 3, wherein the ventilation block member is attached to one of the transfer member holder and the outer shell member, and a sliding contactable film is attached to a portion facing the other. Forming equipment.   The transfer member holder is a movable holder capable of pressing and separating the transfer member with respect to the image carrier, and is driven to swing around a fulcrum on the outer shell member so that the transfer member is pressed against and separated from the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus can be used.   6. The image forming apparatus according to claim 1, wherein an air inlet is formed in the recording medium guide portion of the outer shell member and the recording medium guide portion air inlet communicates with the air intake device.   The recording medium guide portion of the outer shell member includes a metal guide plate for recording medium guide and an attachment portion of the metal guide plate, and corresponds to the opening formed in the metal guide plate and the opening. The image forming apparatus according to claim 6, wherein the recording medium guide portion intake port is formed by an opening formed in the metal guide plate attachment portion.   The end of the recording medium guide portion on the recording medium entrance side is at least the end of the nip portion and the end of the transfer member holder on the image carrier side in a state where the transfer member is in pressure contact with the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus does not protrude toward the image carrier side from an extended line of connecting straight lines.   The image forming apparatus according to claim 1, wherein the intake device includes an intake duct that communicates with a vent of the outer shell member, and the intake duct is formed integrally with the outer shell member. apparatus.   The image forming apparatus according to claim 1, wherein the transfer member holder includes a neutralizing member for neutralizing a recording medium discharged from the nip portion at an end portion on the image carrier side.   The image forming apparatus according to claim 1, wherein the transfer member is a transfer roller.