JP3919760B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to an improvement in an image forming apparatus in which a transfer unit is disposed on a rotation support unit that is rotatably supported by a main body of the image forming apparatus.

As an example of a conventional image forming apparatus, an intermediate transfer type image forming apparatus will be described as an example. A predetermined color component image (a toner image in the case of an electrophotographic system) is formed on a latent image carrier such as a photosensitive drum. After forming and primary-transferring the color component image on the latent image carrier to an intermediate transfer member such as an intermediate transfer belt, the color component image on the intermediate transfer member is batch-recorded on the recording material by a transfer unit for secondary transfer ( A secondary transfer is already provided.
As this type of transfer unit, for example, a unit case in which a transfer roll is rotatably supported on a unit case and this unit case is supported by a door unit (provided to be openable and closable on the image forming apparatus main body) is known. ing.
Further, since there is a concern that untransferred toner or the like adheres to the transfer roll, an aspect in which a cleaning member is provided as a transfer unit for cleaning the transfer roll is already known.

By the way, a member such as a door unit of the image forming apparatus main body is often a low-rigidity module with poor positional accuracy from the viewpoint of weight reduction, and the transfer unit is not positioned with respect to the module. Usually, a state where the intermediate transfer member is in contact with a backup roll (opposing roll) in a predetermined nip region is set as an operation position for image formation, and is positioned.
If the image forming process of the image forming apparatus is four cycles, or if there is a concern that a long-term contact state may lead to deformation of the transfer roll depending on the material of the transfer roll, a cycle other than the cycle for transferring to the recording material. In many cases, when the power is turned off, the transfer roll is made to stand by at a retract position separated from the set position.

Further, in the transfer roll type image forming apparatus described above, a measure is taken so that the transfer conditions are not deteriorated by the nip pressure change of the transfer roll.
For example, a technique for positioning the transfer unit on the intermediate transfer unit with a positioning pin or the like (for example, refer to Patent Documents 1 and 2), or a repulsive force is generated from the intermediate transfer member side when the transfer roll is pressed, so A technique (for example, see Patent Document 3) for preventing changes in transfer conditions due to movement of the position of the transfer body has been proposed.

Japanese Patent Laid-Open No. 11-24528 (Example, FIG. 5) Japanese Patent Laid-Open No. 10-293478 (Embodiment of the Invention, FIG. 2) Japanese Patent Laid-Open No. 11-265123 (Embodiment of the Invention, FIG. 1)

However, in the aspect in which the transfer unit is disposed on the rotation support unit such as the door unit, the following technical problems have been found.
For example, when an intermediate transfer type image forming apparatus including a belt unit such as an intermediate transfer belt and a transfer unit is taken as an example, when the transfer unit is replaced, the image forming apparatus main body is rotatably provided. The transfer unit can be attached and detached by opening the door unit. For example, when replacing the belt unit using the opening of the same door unit, the transfer unit located closer to the door unit than the belt unit is used. After removing the unit, it is necessary to pull out the belt unit, and there is a technical problem that the attaching / detaching operation of the belt unit becomes troublesome.

Such a technical problem occurs not only in the intermediate transfer type image forming apparatus but also in an image forming apparatus in which the transfer unit is disposed in the rotation support unit.
The present invention has been made in order to solve the above technical problem, and is an image forming apparatus capable of improving maintenance workability on the premise of a mode in which a transfer unit is disposed in a rotation support unit. It is to provide.

That is, the present invention relates to a plurality of photosensitive drums that carry a visible image, a belt unit that includes an intermediate transfer belt that is disposed opposite to the photosensitive drums and transfers and carries a visible image on each photosensitive drum, and an intermediate transfer pressed through the recording material on the belt surface, in an image forming apparatus and a transfer member for collectively transferred onto a recording material a visible image on the intermediate transfer belt, pivoted on one side of the image forming apparatus main body while a side door for opening and closing the mounted for Rutotomoni image forming apparatus main body, provided for the side doors of the one, the incorporation of the transfer member in one of the unit case, closing the side door When operating, the transfer member can be positioned in a positioning groove provided on the image forming apparatus main body side, and when the side door is closed, the transfer member can be brought into and out of contact with the intermediate transfer belt. Unite A transfer unit which is held movably per scan, upon openably provided and open to Rutotomoni image forming apparatus main body is provided on the other side of the inverse of the image forming apparatus main body and the one side door And the other side door having an opening through which the belt unit can be pulled out separately from the photosensitive drum (see Embodiment 3).

In such technical means, representative embodiments of the image forming apparatus, the intermediate transfer belt image bearing member is transferred carries a visible image is opposed to these and a plurality of photosensitive drums each photoconductor on the drum There a belt unit that is provided, the transfer unit include those which are opposed to the belt unit.
In this aspect, the belt unit mounting / removal structure is preferably an aspect in which the belt unit can be pulled out horizontally from the side of the image forming apparatus main body through the opening when the other side door is opened.
Furthermore, as an attachment / detachment structure of the photosensitive unit including the photosensitive drum, an aspect in which the photosensitive unit including the photosensitive drum can be pulled out from the front side of the image forming apparatus main body is preferable.
Furthermore, as an aspect at the time of pulling out the photoreceptor unit and the belt unit, an aspect in which the photoreceptor unit and the belt unit are arranged in a non-contact manner when the photoreceptor unit or the belt unit is pulled out is preferable. Thus, if both are arrange | positioned non-contactingly, the damage of each part accompanying drawing operation can be prevented effectively.

Moreover, in the aspect which arrange | positioned the transfer unit in one side door (rotation support unit) like this invention, the aspect shown to Fig.1 (a)-(c) is preferable.
The first embodiment is an improvement in blowing out cleaning residues such as a toner cloud. As shown in FIG. 1A, the image forming engine 1 includes an image carrier 2 that carries a visible image. In the image forming apparatus comprising the transfer member 3a that is pressed against the surface side of the image carrier 2 via a recording material and collectively transfers the visible image on the image carrier 2 to the recording material. Hereinafter, in the section of “Means for Solving the Problems”, it is referred to as an apparatus main body) 4 and a rotation support unit 5 that is rotatably supported, and the transfer member 3a and a cleaning member 3b for cleaning the transfer member 3a. And a transfer unit 3 incorporated in one unit case 3c, and the transfer unit 3 is attached to the rotation support unit 5 together with the unit case 3c so that the transfer member 3a can contact and separate from the image carrier 2. That it was held freely It is an butterfly.

  For example, as shown in FIGS. 23 (a) and 23 (b), a conventional transfer unit mounting structure has a transfer unit 810 disposed on a door unit 800 having a rotation fulcrum 801, and the transfer unit 810 includes a door. A transfer roll 812 is disposed in an opening of a unit case 811 fixed to the unit 800, a cleaning brush 813 that contacts the transfer roll 812 is disposed in the unit case 811, and the transfer roll 812 is retracted. The transfer roll 812 is supported by a swing arm 822 that swings by an eccentric cam 821, and the swing arm 822 is supported by a biasing spring 823 in a predetermined direction. It is what I did. In FIGS. 23A and 23B, reference numeral 830 denotes a belt unit having an intermediate transfer belt 831. A back-up roll 832 serving as a stretching roll is provided on the back of the intermediate transfer belt 831 facing the transfer roll 812. ing.

In this type of embodiment, in order to enable the retraction operation of the transfer roll 812, the transfer roll 812 is supported by the swing arm 822, so that the transfer locus of the transfer roll 812 is inevitably changed. In consideration of this, it is essential to secure a wide opening area of the unit case 811.
For this reason, a relatively wide gap is formed between the opening of the unit case 811 and the transfer roll 812. For example, as shown in FIG. 23A, the transfer roll 812 is moved between the set position and the retract position. There is a concern that the toner cloud 840 may be blown out from the gap between the unit cases 811 under the condition of moving between the two.
Further, as shown in FIG. 23 (b), the door unit 800 is opened during jam processing and maintenance, and the unit case 811 of the transfer unit 810 is opened and closed when the door unit 800 is opened and closed. There is a concern that the toner cloud 840 may blow out from the gap.

On the other hand, according to the first aspect (see FIG. 1A), the retraction operation of the transfer member 3a alone is eliminated, and the retraction operation for each unit case 3c is performed, thereby minimizing the opening width of the unit case 3c. It is possible to prevent the cleaning residue from blowing out from the unit case 3c.
Thus, according to the first aspect, since the transfer unit and the cleaning member are incorporated into one unit case, the transfer unit is movable with respect to the rotation support unit together with the unit case. There is no relative movement of the transfer member, and accordingly, the opening area of the unit case can be set according to the size of the transfer member, and the gap between the unit case and the transfer member can be minimized. .
For this reason, even if the transfer unit is contacted / separated or the rotation support unit is opened / closed during jam processing or maintenance, the cleaning residue in the unit case cleaned by the cleaning member is unnecessarily blown out from the opening gap. The situation can be effectively prevented, and adverse effects such as contamination of the recording material caused by blowing out the cleaning residue can be effectively avoided.

In such technical means, this mode is premised on a mode in which the transfer member 3 a and the cleaning member 3 b are accommodated in the transfer unit 3.
Here, the transfer member 3a may be appropriately selected as long as it is a member capable of contact transfer such as a roll and a belt, and the cleaning member 3b includes various modes such as a brush and a blade.
Further, the unit holding mechanism 6 that holds the transfer unit 3 may be any unit that can hold the unit case 3c so as to be movable, and is not limited to a mode in which the transfer is supported.
Here, as a typical mode of the unit holding mechanism 6, the unit case 3c is rotatably supported by the rotation support unit 5, and a part separated from the rotation center of the unit case 3c is moved up and down by an elevating member. The unit case 3c is swung around the rotation center 3c so that the transfer member 3a can be brought into contact with and separated from the image carrier 2.
The image forming engine 1 includes various forms, and the image carrier 2 only needs to carry a visible image, and is not limited to a belt shape, a drum shape, or the like. The number may be single or plural.

Further, in such an aspect, the transfer unit 3 includes a cleaning residue container in the unit case 3c, and the unit case 3c has a partitioning part in which the cleaning member disposing part and the cleaning residue container are partitioned. Is preferably provided.
In this case, since the transfer unit 3 contacts and separates together with the unit case 3c, it is possible to avoid a situation in which the cleaning residue reattaches to the cleaning member 3b when the transfer unit 3 contacts and separates.
Moreover, as a partition part, you may provide in unit case 3c integrally, and you may provide another member.
Further, in this embodiment, the transfer member 3a of the transfer unit is positioned while being in contact with the positioning member 7 (indicated by the phantom line in the drawing) in the setting process of being placed in contact with the image carrier 2, and the transfer unit 3 The cleaning member 3b is preferably arranged in a direction in which the rotational load is small relative to the rotational direction of the transfer member 3a that rolls in contact with the positioning member 7.
In this case, the load variation of the transfer member 3a when the transfer unit 3 is set can be suppressed, and the position reproducibility of the transfer member 3a due to the load variation can be improved.

In particular, in the aspect in which the image carrier 2 is provided with a cleaning member that can be cleaned, the transfer member 3a of the transfer unit 3 is positioned while being in contact with the positioning member 7 and rolling in the setting process of placing the image carrier 2 in contact. The cleaning member 3b of the transfer unit 3 is disposed in a direction in which the rotational load is small relative to the rotation direction of the transfer member 3a that rolls in contact with the positioning member 7, and further, a cleaning member (not shown) of the image carrier 2 is provided. The positioning member 7 is preferably arranged in a direction in which the rotational load is small with respect to the rotation direction of the image carrier 2 that rotates in contact with the transfer member 3 a that rolls in contact with the positioning member 7.
In this case, in the aspect provided with the cleaning member for the image carrier 2, it is possible to suppress the load fluctuation of the transfer member 3a when the transfer unit 3 is set, and to improve the position reproducibility of the transfer member 3a due to the load fluctuation.

The second mode is to improve the change of transfer conditions. As shown in FIG. 1B, an image forming engine 1 including an image carrier 2 that carries a visible image, and an image carrier. In an image forming apparatus provided with a transfer member 3a that is pressed against the surface side of the recording medium 2 via a recording material and collectively transfers a visible image on the image carrier 2 to the recording material, the image forming apparatus 4 is rotatable with respect to the apparatus main body 4. And the rotation support unit 5 supported by the unit, and the transfer member 3a is incorporated into one unit case 3c, and the transfer member 3a is united with respect to the rotation support unit 5 so that the transfer member 3a can contact and separate from the image carrier 2. A transfer unit 3 that is movably held together with the case 3 c, and a unit holding mechanism 6 that holds the transfer unit 3 rotatably supports the unit case 3 c on the rotation support unit 5. Rotation support of case 3c The setting force F is applied to a part away from 3d, the reaction force R from the rotation fulcrum 3d of the unit case 3c is set in the direction of the rotation fulcrum 5d of the rotation support unit 5, and the reaction force of the setting force F is counteracted. The moment M around the rotation fulcrum 5d of the rotation support unit 5 by force is set in a direction in which the rotation support unit 5 is rotated toward the apparatus main body 4 side.
In addition, the transfer unit 3 of this aspect should just be equipped with the transfer member 3a at least in the unit case 3c, and it is not essential to provide the cleaning member 3b.

Here, in the conventional mode in which the transfer unit is disposed on the rotation support unit such as the door unit, the transfer roll is pressed against the backup roll of the intermediate transfer belt. A reaction force inevitably acts on the area, and this reaction force acts in the direction of opening the door unit, and there is a concern that even the door unit is slightly deformed in the opening direction.
Under such circumstances, there is a concern that the positioning accuracy of the transfer unit disposed in the door unit may be affected, and the transfer condition of the transfer roll may change, such as a change in the nip pressure of the transfer roll. There is.

On the other hand, according to this aspect (see FIG. 1B), the moment generated by the nip force of the transfer member 3a with respect to the rotation support unit 5 is canceled, thereby suppressing the deformation of the rotation support unit 5. The positional accuracy of the transfer member 3a can be kept good.
Thus, according to the second aspect, during the setting process of the transfer unit, a nip load or the like of the transfer member is received at the rotation fulcrum of the rotation support unit, and the rotation support unit is rotated toward the apparatus main body. Since the moment is applied, the reproducibility of the position of the transfer member can be secured even when the rigidity of the rotation support unit is lowered.
As a result, the transfer operation by the transfer member can always be performed satisfactorily, defects (such as jams) can be effectively prevented from changing in the peeling posture of the recording material, and the image quality of color images and the like is always kept good. be able to.

  In addition, as shown in FIG. 1B, a modified embodiment of the second embodiment includes an image forming engine 1 including an image carrier 2 that carries a visible image, and a recording material on the surface side of the image carrier 2. And a transfer member 3a that collectively transfers a visible image on the image carrier 2 to a recording material, and a rotation support that is rotatably supported with respect to the apparatus body 4 The unit 5 and the transfer member 3a are assembled in one unit case 3c, and the unit case 3c is movably held with respect to the rotation support unit 5 so that the transfer member 3a can be brought into and out of contact with the image carrier 2. The unit holding mechanism 6 that holds the transfer unit 3 rotatably supports the unit case 3c on the rotation support unit 6, and in the process of setting the transfer unit 3, the rotation fulcrum 3d of the unit case 3c. Set the site away from A moment around the rotation fulcrum 5d ′ (indicated by the dotted line in FIG. 1 (b)) of the rotation support unit 5 due to the reaction force R from the rotation fulcrum 3d of the unit case 3c. The sum M ′ with the moment around the rotation fulcrum 5 d ′ of the rotation support unit 5 due to the reaction force of the force F is the direction to rotate the rotation support unit 5 toward the apparatus main body 4, or substantially 0 It is characterized by being.

In this case, the moment around the rotation fulcrum 5d ′ of the rotation support unit 5 due to the reaction force from the rotation fulcrum 3d of the unit case 3c is usually the rotation fulcrum of the rotation support unit 5 due to the reaction force of the set force F. This is opposite to the moment around 5d ′, which is preferable in that the moment acting on the rotation support unit 5 can be reduced.
For this reason, even if the rigidity of the rotation support unit 5 is reduced, the deformation of the rotation support unit 5 can be suppressed.
In particular, it is preferable that the sum of both moments is substantially zero in that the deformation of the rotation support unit 5 is substantially completely prevented.
Thus, according to the modification of the second aspect, the nip load or the like of the transfer member is received in the vicinity of the rotation fulcrum of the rotation support unit, and the rotation support unit is rotated toward the apparatus main body. If a moment is given or the moment is made substantially zero, the position reproducibility of the transfer member can be kept good while reducing the rigidity of the rotation support unit.

Further, the third aspect is to improve the decrease in maintenance workability. As shown in FIG. 1C, an image forming engine 1 including an image carrier 2 that carries a visible image, and an image carrier. In an image forming apparatus provided with a transfer member 3a that presses against the surface side of the body 2 via a recording material and collectively transfers a visible image on the image carrier 2 to the recording material, the image forming apparatus rotates with respect to the apparatus body 4 A rotation support unit 5 that is freely supported, and the rotation support unit 5 so that the transfer member 3a is incorporated in one unit case 3c and the transfer member 3a can contact and separate from the image carrier 2. A transfer unit 3 that is movably held together with the unit case 3c is provided, and maintenance parts (for example, the image carrier 2) of the image forming engine 1 can be exchanged in a state where the transfer unit 3 is disposed at the set position. Image creation engine 1 In which is disposed movably Tenansupatsu.
In addition, the transfer unit 3 of this aspect should just be equipped with the transfer member 3a at least in the unit case 3c, and it is not essential to provide the cleaning member 3b.

Here, in the conventional mode, when the intermediate transfer unit is replaced, if the intermediate transfer unit is inserted and removed while the transfer roll is nipped, the intermediate transfer belt moves while sliding on the transfer roll. There is a concern that the intermediate transfer belt may be damaged. For this reason, when replacing the intermediate transfer unit, a technique has been adopted in which the door unit is opened to separate the transfer unit from the intermediate transfer unit.
When replacing the image forming photosensitive unit or the like, the photosensitive drum and the intermediate transfer belt are separated from each other in order to prevent damage to the photosensitive drum. Since the transfer unit could not be inserted / removed immediately, there was a restriction in maintenance work that the photosensitive unit had to be replaced by separating the photosensitive unit from the intermediate transfer unit.
Thus, in the aspect which arrange | positions a transfer unit in a rotation support unit, there exists a point in which maintenance workability | operativity is still inadequate.

On the other hand, according to the present embodiment (see FIG. 1C), the maintenance unit of the image forming engine 1, for example, the belt unit that is the image carrier 2 is connected to the transfer unit 3 at the set position, for example. Therefore, the replacement workability of the maintenance parts of the image forming engine 1 can be improved.
As described above, according to the third aspect, since the maintenance parts of the image forming engine are movably disposed while the transfer unit is arranged at the set position, the maintenance work is compared with the maintenance work involving the movement of the transfer unit. Can improve sex.

According to the present invention, in an image forming apparatus including a belt unit including a plurality of photosensitive drums and an intermediate transfer belt disposed to face the photosensitive drums, the image forming apparatus is provided on one side of the image forming apparatus main body so as to be rotatable. is and one and the side door of the openable and closable with respect to the image forming apparatus main body while holding the transfer unit, the other side to openably provided and the belt unit can be drawn the other side of the image forming apparatus main body Since it has a side door, it has the following technical effects.
By rotating one of the side doors holding the transfer unit, the transfer unit can be positioned with respect to the belt unit, and the transfer unit can be separated from the belt unit. Can be done easily.
Further, since the belt unit can be pulled out by opening the other side door, interference with the transfer unit on one side door side can be effectively suppressed, and the belt unit can be maintained.
Furthermore, even if there are maintenance parts on both sides of the image carrier (photosensitive drum, intermediate transfer belt) , by opening the side doors on both sides of the image forming apparatus main body, both sides of the image forming apparatus main body are opened. The maintenance work can be accessed from either side, and the maintenance work can be performed efficiently without removing and attaching the image carrier .

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings. The first and second embodiments show a transfer unit mounting structure applicable in the present invention.
Embodiment 1
FIG. 2 is an explanatory view showing Embodiment 1 of a tandem type image forming apparatus to which the present invention is applied.
In the figure, a tandem type image forming apparatus includes an image forming unit 22 (specifically, black, yellow, magenta, and cyan in this embodiment) in a main body housing (corresponding to the image forming apparatus main body) 21. 22a to 22d) are arranged in the horizontal direction, and a belt unit (belt conveying device) 23 including an intermediate transfer belt 230 that is circulated and conveyed along the arrangement direction of the respective image forming units 22 is disposed above it. On the other hand, a recording material supply cassette (not shown) in which a recording material (not shown) such as paper is accommodated is disposed below the main body housing 21, and a recording material conveyance path from the recording material supply cassette is provided. The recording material conveyance path is arranged in the vertical direction.

In the present embodiment, each of the image forming units 22 (22a to 22d) is, for example, for black, yellow, magenta, and cyan in order from the upstream side in the circulation direction of the intermediate transfer belt 230. (Not limited) toner image, each photosensitive unit 30, each developing unit 33, and one common exposure unit 40.
Here, the photoconductor unit 30 includes, for example, a photoconductor drum 31, a charger (charging roll in this example) 32 that charges the photoconductor drum 31 in advance, and a cleaner 34 that removes residual toner on the photoconductor drum 31. Are integrated into a cartridge.
The developing unit 33 develops the electrostatic latent image exposed and formed by the exposure unit 40 on the charged photosensitive drum 31 with a corresponding color toner (for example, negative polarity in the present embodiment). is there.
On the other hand, the exposure unit 40 corresponds to, for example, four semiconductor lasers (not shown), one polygon mirror (not shown), an imaging lens (not shown), and each photoconductor unit 30 in the unit case. A mirror (not shown) is stored, light from a semiconductor laser for each color component is deflected and scanned by a polygon mirror, and an optical image is guided to an exposure point on the corresponding photosensitive drum 31 via an imaging lens and mirror. It is what I did.

Further, in the present embodiment, the belt unit 23 is a belt in which an intermediate transfer belt 230 is stretched between a plurality of stretching rolls 231 to 236, and an intermediate transfer corresponding to the photosensitive drum 31 of each photosensitive unit 30. A primary transfer device (primary transfer roll in this example) 51 is disposed on the back surface of the belt 230, and a voltage having a polarity opposite to the charging polarity of the toner is applied to the primary transfer device 51, so The toner image is electrostatically transferred to the intermediate transfer belt 230 side.
Here, the intermediate transfer belt 230 uses a resin such as polyimide, polycarbonate, polyester, polypropylene, or various rubbers containing an appropriate amount of an antistatic agent such as carbon black, and has a volume resistivity of 10 ⁶ to 10 ¹⁴ Ω. The thickness is set to about 0.1 mm, for example.
On the other hand, the tension roll 231 is a steering drive roll that tilts to control the meandering in the lateral direction orthogonal to the traveling direction of the intermediate transfer belt 230 and drives the intermediate transfer belt 230. Reference numerals 232 and 233 denote surface-developing rolls (both driven rolls) for exposing the primary transfer surface of the intermediate transfer belt 230 to each image forming unit 22 (22a to 22d) to a predetermined position. Reference numeral 234 denotes a tension roll that is pressed against the intermediate transfer belt 230 with a predetermined tension by a biasing spring (not shown) to adjust the deflection of the intermediate transfer belt 230. Further, the tension roll 235 is a secondary transfer described later. It is a recording material posture adjusting roll that regulates the posture of the recording material entering the transfer nip area of the unit 52, and also a tension roller 236 is a roll (driven roll) which also serves as a backup roll below secondary transfer unit 52.

Further, a secondary transfer unit 52 is disposed at a portion corresponding to the tension roll 236 on the downstream side of the most downstream image forming unit 22d of the intermediate transfer belt 230, and a primary transfer image on the intermediate transfer belt 230 is recorded. Secondary transfer (collective transfer) is performed on the material.
In the present embodiment, the secondary transfer unit 52 is provided with a secondary transfer roll 522 in the opening of the unit case 521, and this secondary transfer roll is used as a backup roll (in this example, the tension roll 236 is also used). For example, the secondary transfer roll 522 is grounded and a bias having the same polarity as the charging polarity of the toner is applied to the backup roll (stretching roll 236).
Here, the secondary transfer roll 522 is made of urethane rubber tube with carbon dispersed on the surface, the inside is made of foamed urethane rubber with carbon dispersed, and further, the roll surface is coated with fluorine, and its volume resistivity is 10 ³ to 10 ^10. The roll diameter is Ω · cm, for example, φ28 mm, and the hardness is set to 30 ° (Asuka C), for example.
The backup roll 236 includes a tube of EPDM and NBR blend rubber in which carbon is dispersed on the surface, and the inside is formed of EPDM rubber, and its surface resistivity is 10 ⁷ to 10 ¹⁰ Ω / □. The roll diameter is, for example, 28 mm, and the hardness is set to 70 ° (Asuka C), for example.
In particular, in the present embodiment, the secondary transfer unit 52 includes a cleaning brush 523 that cleans the surface of the secondary transfer roll 522 in the unit case 521.
The mounting structure and drive system of the secondary transfer unit 52 will be described later.

Furthermore, a belt cleaner 53 is disposed on the upstream side of the most upstream image forming unit 22a of the intermediate transfer belt 230 so as to remove residual toner on the intermediate transfer belt 230.
A recording material supply cassette (not shown) is provided with a feed roll (not shown) for picking up the recording material, and a takeaway roll for sending the recording material is disposed immediately after the feed roll, and recording is performed. A suitable number of transport rolls 61 are disposed in the material transport path, and a registration roll that supplies the recording material to the secondary transfer site at a predetermined timing in the recording material transport path positioned immediately before the secondary transfer site. (Registration roll) 62 is disposed.
On the other hand, a fixing device 66 is provided in the recording material conveyance path located downstream of the secondary transfer site, and a discharge roll (not shown) for discharging the recording material is provided downstream of the fixing device 66. The recording material is accommodated in an accommodation tray 68 formed in the upper part of the main body housing 21.

Next, the mounting structure of the secondary transfer unit 52 will be described.
In the present embodiment, as shown in FIGS. 2 to 4, a door unit 70 is supported on the side of the main body housing 21 so as to be openable and closable around a rotation fulcrum 71. Further, the secondary transfer unit 52 is attached via a retract mechanism 80.
Here, the secondary transfer unit 52 has a pivot fulcrum (configured with pins in this example ) 524 on both sides of the unit case 521, and a bracket 73 (an imaginary line in FIG. 4) attached to the frame 72 of the door unit 70. A long hole 74 (indicated by a phantom line in FIG. 4) is formed, and the rotation fulcrum 524 is locked in the long hole 74 so as to be pivotally supported.

  In this embodiment, as shown in FIGS. 4 and 5, the retract mechanism 80 is provided with an eccentric cam 81 that is rotated by a lifting motor (not shown), and a slide lever 82 is provided above the eccentric cam 81. Is held by a guide roller 83 (see FIG. 6), and a bent portion 82a facing the surface of the eccentric cam 81 is formed at the lower end of the slide lever 82, and the tip of the lower bent portion 82a is attached. A bending portion 82b is formed at the upper end of the slide lever 82, which is inclined obliquely downward from the horizontal direction. The upper end bending portion 82b and the secondary transfer unit are urged downward by the biasing spring 84. A part of the 52 unit cases 521 spaced from the rotation fulcrum 524 (in this example, the upper part of the unit case 521) is connected and fixed by a connecting rod 85.

On the other hand, on the belt unit 23 side, as shown in FIGS. 2 to 4, a positioning plate 90 (indicated by phantom lines in the figure) for positioning the secondary transfer roll 522 at the set position is disposed. A V-shaped positioning groove 91 for positioning the secondary transfer roll 522 is formed in the positioning plate 90, and a support shaft portion of the secondary transfer roll 522 is brought into contact with any edge portion of the positioning groove 91. The secondary transfer roll 522 is positioned in the positioning groove 91 by being guided and moved to the back of the positioning groove 91 (corresponding to the set position).
2 to 4, reference numeral 63 denotes a conveyance chute provided on the downstream side of the registration roll 62. When the door unit 70 is opened, one conveyance chute is opened together with the one registration roll 62 together with the door unit 70. Reference numerals 64 and 65 are conveyance guides provided on the downstream side of the secondary transfer portion and guiding and conveying the recording material toward the fixing device 66. In this example, the conveyance guides are opened together with the door unit 70. It has become.

A drive system 100 of the secondary transfer unit 52 used in this embodiment is shown in FIGS.
In the figure, the drive system 100 of the secondary transfer unit 52 has a drive motor 101 fixedly disposed on a main body housing 21 (see FIG. 2), and a drive transmission gear 102 is coaxially fixed to the drive shaft of the drive motor 101. On the other hand, the driven transmission gear 103 is coaxially fixed to one end of the secondary transfer roll 522, and the secondary transfer roll 522 is set to the set position (see FIG. 7A) or retracted position (FIG. 7B). The drive transmission gear 102 and the driven transmission gear 103 are engaged with each other under any of the situations located in the reference).
7A and 7B, the same components as those in FIGS. 2 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted here.

Next, an image forming process of the image forming apparatus according to the present embodiment will be described.
Each image forming unit 22 (22 a to 22 d) forms each color component image (toner image) on the photosensitive drum 31, and sequentially transfers each color component image onto the intermediate transfer belt 230 by the primary transfer device 51.
On the other hand, a recording material is supplied from a recording material supply cassette from outside the figure, and is conveyed to a secondary transfer portion through a registration roll 62 at a predetermined timing.
Then, the multiple transfer image primarily transferred onto the intermediate transfer belt 230 is conveyed to the secondary transfer portion and is collectively transferred to the recording material by the secondary transfer unit 52.
Thereafter, the recording material fixes the images transferred in a batch via the fixing device 66 and then is discharged to the storage tray 68 through a discharge roll (not shown).
In each image forming unit 22, the residual toner on the photosensitive drum 31 is cleaned by the cleaner 34, while the residual toner on the intermediate transfer belt 230 is cleaned by the belt cleaner 53.

In such an image forming process, the secondary transfer unit 52 moves the secondary transfer roll 522 from the retract position (see FIG. 5B) to the set position (see FIG. 5A) immediately before performing the secondary transfer operation. When the secondary transfer operation is completed, or when the power is turned off, the set position is retracted to the retract position.
Here, the operation state of the retract mechanism 80 when the secondary transfer roll 522 is located at the set position will be described. In the retract mechanism 80, the cam surface of the eccentric cam 81 is in the lowest position (see FIG. 5A). It is in.
At this time, the lower end bent portion 82 a of the slide lever 82 is not in contact with the cam surface of the eccentric cam 81, and the slide lever 82 is pushed downward by the biasing spring 84.
Then, the unit case 521 rotates about the rotation fulcrum 524 in the direction of the arrow, and the secondary transfer roll 522 in the unit case 521 approaches the backup roll 236 side, and enters the positioning groove 91 of the positioning plate 90. Engaged and positioned.

On the other hand, the operation state of the retract mechanism 80 when the secondary transfer roll 522 is located at the retract position will be described. In the retract mechanism 80, the cam surface of the eccentric cam 81 is in the highest position (see FIG. 5B). is there.
At this time, the lower bent portion 82 a of the slide lever 82 is pushed up by the eccentric cam 81, and the slide lever 82 is pushed up against the biasing force of the biasing spring 84.
Then, the unit case 521 rotates about the rotation fulcrum 524, the secondary transfer roll 522 in the unit case 521 moves away from the backup roll 236, and reaches a retract position separated from the set position. .

In this example, the retract mechanism 80 includes a delay circuit that works when the power is turned off, and can move the secondary transfer roll 522 to the retract position when the power is turned off.
For this reason, in this embodiment, when the power is turned off, the retract mechanism 80 operates to set the secondary transfer roll 522 to the retract position at all times. Therefore, when the power is turned on, the secondary transfer unit 52 starts to operate from a state where the secondary transfer roll 522 is held at the retract position.

In the present embodiment, the drive system 100 of the secondary transfer unit 52 is driven by the drive motor 101 even when the secondary transfer roll 522 is located at the retract position, as shown in FIG. 7B. Since the coupled drive transmission gear 102 and the driven transmission gear 103 mesh with each other, the secondary transfer roll 522 is immediately driven to rotate.
Therefore, when the secondary transfer roll 522 is moved from the retract position (see FIG. 7B) to the set position (see FIG. 7A), the secondary transfer roll 522 is set to the set position while rotating. can do.
Therefore, even if the intermediate transfer belt 230 is rotated in advance before the secondary transfer roll 522 reaches the set position and the image forming process of each image forming unit 22 is started, the secondary transfer roll 522 reaches the set position. Thus, at the moment of contact with the intermediate transfer belt 230, a speed fluctuation is caused in the intermediate transfer belt 230, and there is no adverse effect on image positional deviation and motion quality of the intermediate transfer belt 230.

In this embodiment, the position of the drive transmission gear 102 is uniquely determined based on the positional relationship with the drive motor 101, but the position of the driven transmission gear 103 depends on the position change of the secondary transfer roll 522. Move with it.
Therefore, in the present embodiment, when the secondary transfer roll 522 is positioned at the set position (see FIG. 7A), the drive transmission gear 102 and the driven transmission gear 103 are meshed at the normal position, and the secondary transfer roll 522 is engaged with the secondary transfer roll 522 at the normal position. A stable rotational drive is applied to the transfer roll 522.
However, when the secondary transfer roll 522 is positioned at the retracted position (see FIG. 7B), the meshing state of both the gears 102 and 103 is deviated from the normal position, but the tooth tip radius of both the gears 102 and 103 is the same. If the distance between the centers of the two gears 102 and 103 is entered below the total, the meshing state of the two gears 102 and 103 is maintained.

Further, in the present embodiment, when a jam occurs in the recording material during the transfer operation by the secondary transfer unit 52, the door unit 70 is opened as shown in FIGS. Can be jammed.
In this case, the secondary transfer unit 52 is opened together with the door unit 70, but the secondary transfer unit 52 is configured by incorporating the secondary transfer roll 522 and the cleaning brush 523 into the unit case 521, and the retract mechanism 80. Accordingly, the secondary transfer unit 52 moves together with the unit case. Therefore, it is only necessary to secure the opening of the unit case 521 by a size corresponding to the secondary transfer roll 522, and the unit case 521, the secondary transfer roll 522, and the like. There is no unnecessary gap between them.
Therefore, even if the secondary transfer unit 52 rotates together with the door unit 70, there is no possibility that the toner cloud is unnecessarily blown out from the opening of the unit case 521.

In the present embodiment, the drive system 100 of the secondary transfer unit 52 fixes the driven transmission gear 103 coaxially with the secondary transfer roll 522. However, the present invention is not limited to this. Instead, for example, a drive system 100 as shown in FIGS. 8A and 8B may be adopted.
In the drive system 100 of the secondary transfer unit 52 in the figure, a drive motor 111 is fixedly disposed on a main body housing 21 (see FIG. 2), and a drive transmission gear 112 is coaxially fixed to a drive shaft of the drive motor 111. The driven transmission gear 113 is coaxially fixed to the rotation fulcrum 524 of the unit case 521 of the secondary transfer unit 52, and the driven transmission is transmitted to the driven transmission gear 114 fixed coaxially to the secondary transfer roll 522. The drive transmission gear 112 is engaged under any situation where the gear 113 is engaged and the secondary transfer roll 522 is located at the set position (see FIG. 8A) or the retract position (see FIG. 8B). And the driven transmission gear 113 are meshed with each other.

Here, the retraction mechanism 80 causes the unit case 521 to rotate about the rotation fulcrum 524, and this rotation fulcrum 524 is a link that engages with the elongated hole 74 of the bracket 73 of the door unit 70. Since it is a mechanism, there is little variation in the position of the rotation fulcrum 524 that is the center of rotation of the link mechanism.
For this reason, in this example, the driven transmission gear 113 is fixed to the rotation fulcrum 524 of the unit case 521 with little position fluctuation, and the meshing state with the drive transmission gear 112 at each position can be maintained. It is.
In this example as well, when the secondary transfer roll 522 is positioned at the set position (see FIG. 8A), the drive transmission gear 112 and the driven transmission gear 113 are meshed at the regular position, and the secondary transfer roll 522 is engaged. Is provided with a stable rotational drive.
However, when the secondary transfer roll 522 is positioned at the retracted position (see FIG. 8B), the meshing state of both the gears 112 and 113 is deviated from the normal position, but the tooth tip radius of both the gears 112 and 113 is the same. If the distance between the centers of the two gears 112 and 113 is set below the total, the meshing state of the two gears 112 and 113 is maintained.

In the present embodiment, toner residue due to the cleaning brush 523 is accumulated in the unit case 521 of the secondary transfer unit 52.
At this time, as shown in FIG. 9, when the residual toner accumulation portion 120 is secured in the lower region of the unit case 521, the secondary transfer unit 52 largely rotates when the door unit 70 is opened and closed. There is a concern that the toner accumulated on the accumulation unit 120 flows back to the cleaning brush 523 side and reattaches, and this may contaminate the secondary transfer roll 522.
For this reason, in the present embodiment, it is preferable to provide a partition part 121 between the arrangement part of the cleaning brush 523 and the residual toner accumulation part 120 in the unit case 521.
Here, as the partition part 121, as shown in FIG. 9, a partition wall that protrudes inward may be provided in a part of the unit case 521, or the partition by a separate member may be provided in the unit case 521. A wall may be provided.
In FIG. 9, reference numeral 122 denotes an elastic seal lip that is attached to the lower edge of the opening of the unit case 521 and keeps airtight with the secondary transfer roll 522.

Further, in the present embodiment, the direction of the brush body 523a of the cleaning brush 523 is also devised.
That is, in this embodiment, as shown in FIG. 10A, a door unit 70, a secondary transfer unit 52, and a belt unit 23 are provided, and a drive system for the cleaning brush 523 in the secondary transfer unit 52 is provided. As shown in FIG. 10B, a drive transmission gear 131 is provided at one end of the secondary transfer roll 522, while a driven transmission that meshes with the drive transmission gear 131 at one end of the rotating shaft of the cleaning brush 523. A gear 132 is provided, and the cleaning brush 523 is driven to rotate following the secondary transfer roll 522.
In such an aspect, the secondary transfer roll 522 causes the support shaft portion to abut the edge portion of the V-shaped positioning groove 91 of the positioning plate 90 in the setting process, and the support shaft portion is contact-rolled by this edge portion. Although the positioning is performed while moving, the rotation direction when positioning the secondary transfer roll 522 differs depending on which side of the positioning groove 91 is the edge portion.

For example, as shown in FIG. 11 (a), in a mode in which the support shaft portion 522a of the secondary transfer roll 522 abuts on the upper edge portion 91a of the positioning groove 91 and contacts and rolls downward, As indicated by the arrow, the roll 522 rotates counterclockwise, and the cleaning brush 523 rotates counterclockwise.
On the other hand, as shown in FIG. 11B, for example, the support shaft portion 522a of the secondary transfer roll 522 is in contact with the lower edge portion 91b of the positioning groove 91 and rolls in contact with the upper side. As indicated by the arrow, the secondary transfer roll 522 rotates in the clockwise direction, and the cleaning brush 523 rotates in the counterclockwise direction.
At this time, in the present embodiment, the brush body 523a of the cleaning brush 523 is arranged in a direction in which the rotational load is small with respect to the rotation direction of the secondary transfer roll 522, as shown in FIG.
In the embodiment in which the cleaning blade 525 is used instead of the cleaning brush 523, as shown in FIG. 11 (d), the cleaning is performed so that the rotational load is directed in a direction with less rotation relative to the rotation direction of the secondary transfer roll 522. The blade 525 may be disposed.
Accordingly, the load fluctuation of the secondary transfer roll 522 when the secondary transfer unit 52 is set is suppressed, and the position reproducibility of the secondary transfer roll 522 due to the load fluctuation is kept good.

In particular, in the present embodiment, the belt cleaner 53 on the belt unit 23 side includes a cleaning blade 53a in the direction shown in FIG.
Since the cleaning blade 53a is disposed in a direction in which the rotational load is reduced when the intermediate transfer belt 230 rotates in the direction of the arrow, the secondary transfer roll can be used from the viewpoint of suppressing the influence of the rotational load by the cleaning blade 53a. The intermediate transfer belt 230 may be rotated in the above-described direction in the positioning process 522.
In this example, specifically, as shown in FIG. 11B, for example, the support shaft portion 522a of the secondary transfer roll 522 is brought into contact with the lower edge portion 91b side of the positioning groove 91 of the positioning plate 90, If a method of rotating the secondary transfer roll 522 in the arrow direction at the time of positioning is adopted, the intermediate transfer belt 230 is moved in the arrow direction shown in FIG. 10A when the secondary transfer roll 522 contacts the intermediate transfer belt 230. Accordingly, the rotational load on the secondary transfer roll 522 can be further reduced in the positioning process of the secondary transfer roll 522.
Therefore, the load fluctuation of the secondary transfer roll 522 when the secondary transfer unit 52 is set is suppressed to a smaller level, and the position reproducibility of the secondary transfer roll 522 due to the load fluctuation is kept good.

Embodiment 2
FIG. 12 is an explanatory diagram showing a main part of the image forming apparatus according to the second embodiment.
In the figure, the image forming apparatus according to the present embodiment has a basic configuration substantially the same as that of the first embodiment, and further has a force relationship acting on the door unit 70 newly set. Components similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted here.
That is, in the present embodiment, as shown in FIG. 12, the unit case 521 of the secondary transfer unit 52 is pivotally supported by the door unit 70, and the unit case 521 is rotated in the process of setting the secondary transfer unit. The setting force F is applied to the part away from the moving fulcrum 524, but the reaction force R from the rotation fulcrum 524 of the unit case 521 is set in the direction of the rotation fulcrum 71 of the door unit 70, The moment M around the rotation fulcrum 71 of the door unit 70 due to the reaction force of the setting force F is set to rotate the door unit 70 toward the main body housing 21 (see FIG. 2).

Here, as a method of setting the reaction force R from the rotation fulcrum 524 of the unit case 521 in the direction of the rotation fulcrum 71 of the door unit 70, the longitudinal direction of the long hole 74 of the bracket 73 is set to the rotation fulcrum of the door unit 70. What is necessary is just to set it to the tangent direction of the circular locus | trajectory m of the radius which connects 71 and the rotation fulcrum 524 of the unit case 521. FIG.
Further, in this example, the force acting on the secondary transfer unit 52 when the secondary transfer unit 52 is set includes the setting force F from the retract mechanism 80 and the reaction force R acting on the rotation fulcrum 524 as shown in FIG. And the force K applied to the secondary transfer roll 522 side, and if these forces are set to be substantially parallel, these forces F, R, and K are in a balanced relationship of F + R + K = 0. It is in.
In this state, considering the moment M around the door unit 70, the external forces acting on the door unit 70 are F and R, and R is directed toward the rotation fulcrum 71 of the door unit 70. If the moment span up to the point of action of the set force F with respect to the rotation fulcrum 71 is r, the magnitude is M = F · r.

According to this aspect, the reaction force R acting on the rotation fulcrum 524 receives a nip load or the like from the secondary transfer roll 522, and this reaction force R is received by the rotation fulcrum 71 of the door unit 70.
For this reason, the door unit 70 is not unnecessarily distorted and deformed by the reaction force R.
Moreover, since the moment M which rotates toward the main body housing 21 acts on the door unit 70, there is no fear that the door unit 70 is displaced in the opening direction.
Therefore, even if a reaction force R corresponding to the nip force (7 to 10 kgf) of the secondary transfer roll 522 is generated, it is received by the rotation fulcrum 71 of the door unit 70. There is no need for a rigid structure that can withstand a nip force of about 10 kgf.
Further, since the moment M in the closing direction acts on the door unit 70, the positioning accuracy of the secondary transfer roll 522 is kept good, and the position reproducibility of the secondary transfer roll 522 is ensured.

In the modification of the present embodiment, as shown in FIG. 14, the reaction force R (the nip load of the secondary transfer roll 522 and the positioning plate) from the rotation fulcrum 524 of the unit case 521 of the secondary transfer unit 52. 90 corresponding to the reaction force load from the positioning groove 91), the moment M1 around the rotation fulcrum 71 of the door unit 70 (R · r1 if the moment span from the rotation fulcrum 71 is r1) and the set force F The sum of the moment M2 around the rotation fulcrum 71 of the door unit 70 due to the reaction force (F · r2 if the moment span from the rotation fulcrum 71 is r2) rotates the door unit 70 toward the main body housing 21. You may make it direction.
In this aspect, if the nip load of the secondary transfer roll 522 is received near the rotation fulcrum 71 of the door unit 70, the secondary transfer roll can be obtained without increasing the rigidity of the door unit 70 so much. The door unit 70 is not distorted and deformed by the nip load 522 or the like.

Further, since the sum of the moments acts in the direction in which the door unit 70 is closed, the position reproducibility of the secondary transfer roll 522 is also ensured.
In particular, in the present embodiment, since the moment M1 is a component that works in the direction of opening the door unit 70, the total moment itself is suppressed to be smaller than that in the embodiment.
For this reason, distortion deformation due to the moment acting on the door unit 70 is also reduced.
In this modification, the sum of moments may be set to approximately 0. In this case, since the moment does not act in the closing direction of the door unit 70, the door unit 70 is further lowered. It can be rigid.

Embodiment 3
FIG. 15 is an explanatory diagram showing an image forming apparatus according to the third embodiment.
In the figure, the image forming apparatus according to the present embodiment has substantially the same configuration as that of the first embodiment, and further improves maintenance workability.
Components similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted here.
In this example, the belt unit 23 has a belt unit support mechanism 600. The belt unit support mechanism moves the belt unit 23 up and down by rotating the operation arm 601, and guides the guide rail in the raised position. The belt unit 23 can be inserted and removed along the line 602.
The photosensitive unit 30 includes a photosensitive unit support mechanism (not shown) that can be pulled out from the front side of the main body housing.

First, when replacing the secondary transfer unit 52, as shown in FIGS. 16 and 20A and 20B, the secondary transfer unit 52 is removed by opening the door unit 70, while the door unit is opened. The door unit 70 may be closed after the new secondary transfer unit 52 is set to the door unit 70 with the 70 opened.
At this time, as shown in FIG. 20A, when the door unit 70 is opened, the support shaft portion 522a of the secondary transfer roll 522 is guided upward along the positioning groove 91 of the positioning plate 90. When the door unit 70 is closed, the support shaft portion 522 a of the secondary transfer roll 522 is guided downward along the positioning groove 91 of the positioning plate 90.

When the belt unit 23 is replaced, the secondary transfer unit 52 may remain in the set position. First, as shown in FIG. 17, the operation arm 601 of the belt unit support mechanism 600 is pushed down toward the front side. As a result, the belt unit 23 is pushed upward.
At this time, as shown in FIG. 21, the support shaft portion 522 a of the secondary transfer roll 522 is detached from the positioning groove 91 of the positioning plate 90 as the belt unit 23 is raised, and the belt unit 23 is moved to the photosensitive unit 30. It is separated from the photosensitive drum 31.
In this state, as shown in FIGS. 18 and 21, after opening the corresponding side door 610 of the main body housing 21, the belt unit 23 may be pulled out along the guide rail 602 of the belt unit support mechanism 600. .

When the belt unit 23 is attached after replacement, the reverse procedure of the above-described removal process may be performed.
At this time, when the operation arm 601 is raised and lowered after the belt unit 23 is inserted into the main body housing 21, the positioning groove 91 of the positioning plate 90 is in the set position as the belt unit 23 is lowered. Engage with the secondary transfer roll 522 of the transfer unit 52.
When replacing the belt cleaner 53 of the belt unit 23, the belt cleaner 53 is replaced when the belt cleaner 53 is exposed to the outside of the main body housing 21 while the belt unit 23 is being replaced. You can do it.

Further, when the photoreceptor unit 30 is replaced, as shown in FIG. 19, after the belt unit 23 is raised, the front door 611 of the main body housing 21 is opened and the photoreceptor unit 30 is pulled out. .
When the photoconductor unit 30 is mounted, after the new photoconductor unit 30 is inserted into the main body housing 21, the belt unit 23 in the raised position may be lowered.
At this time, as shown in FIG. 22, since the belt unit 23 is merely raised and lowered, the secondary transfer unit 52 may remain in the set position.

(A)-(c) is explanatory drawing which each shows the preferable aspect of the image forming apparatus which concerns on this invention. 1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. (A) is explanatory drawing which shows the state in which the door unit is closed in the image forming apparatus which concerns on this Embodiment, (b) is explanatory drawing which shows the state in which the door unit was opened in the image forming apparatus. It is explanatory drawing which shows the detail of the secondary transfer unit used by this Embodiment. (A) is explanatory drawing which shows the state of a secondary transfer unit when a secondary transfer roll is located in a set position, (b) is the state of a secondary transfer unit when a secondary transfer roll is located in a retract position. It is explanatory drawing shown. FIG. 4 is an explanatory diagram showing a drive system of a secondary transfer unit according to the present embodiment. (A) is explanatory drawing which shows the state of a drive system when a secondary transfer roll is located in a set position, (b) is explanatory drawing which shows the state of a drive system when a secondary transfer roll is located in a retract position. is there. FIG. 6 shows a modified form of the drive system of the secondary transfer unit according to the present embodiment, where (a) is an explanatory diagram showing the state of the drive system when the secondary transfer roll is located at the set position, and (b) is the secondary transfer unit. It is explanatory drawing which shows the state of a drive system when a transfer roll is located in a retract position. It is explanatory drawing which shows the deformation | transformation form of the secondary transfer unit in this Embodiment. (A) is explanatory drawing which shows the layout of the door unit used in this Embodiment, a secondary transfer unit, and a belt unit, (b) is explanatory drawing which shows the drive system of the cleaning brush of a secondary transfer unit. (A) is explanatory drawing which shows an example of the state at the time of positioning of a secondary transfer roll, (b) is explanatory drawing which shows the other example of the state at the time of positioning of a secondary transfer roll, (c) is a brush of a cleaning brush. Explanatory drawing about the direction of a body, (d) is explanatory drawing which shows the example of a layout in the case of using a cleaning blade instead of a cleaning brush. FIG. 6 is an explanatory diagram illustrating a main part of an image forming apparatus used in a second embodiment. FIG. 10 is an explanatory diagram illustrating a balance state of forces of a secondary transfer unit according to the second embodiment. It is explanatory drawing which shows the action state of the moment which acts on the door unit in the deformation | transformation form of Embodiment 2. FIG. FIG. 10 is an explanatory diagram showing an outline of a usage state of an image forming apparatus used in a third embodiment. FIG. 10 is an explanatory diagram illustrating an example of maintenance work when replacing a secondary transfer unit in the third embodiment. In Embodiment 3, it is explanatory drawing which shows the 1st step of the example of a maintenance operation | work at the time of replacing | exchanging a belt unit. In Embodiment 3, it is explanatory drawing which shows the 2nd step of the example of a maintenance operation | work at the time of replacing | exchanging a belt unit. In Embodiment 3, it is explanatory drawing which shows the example of a maintenance operation | work at the time of replacing | exchanging a photoreceptor unit. (A) is explanatory drawing which shows the state of the secondary transfer unit periphery in the example of a maintenance operation | work at the time of removing a secondary transfer unit, (b) is the secondary transfer unit periphery in the example of a maintenance operation | work at the time of mounting | wearing a secondary transfer unit. It is explanatory drawing which shows the state of. FIG. 6 is an explanatory diagram illustrating a state around a secondary transfer unit in an example of maintenance work when replacing a belt unit. FIG. 6 is an explanatory diagram illustrating a state around a secondary transfer unit in an example of a maintenance operation when replacing a photoconductor unit. (A) is explanatory drawing which shows an example of the image forming apparatus of the aspect which has arrange | positioned the secondary transfer unit to the conventional door unit, (b) is explanatory drawing which shows the state which opened the door unit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image formation engine, 2 ... Image carrier, 3 ... Transfer unit, 3a ... Transfer member, 3b ... Cleaning member, 3c ... Unit case, 3d ... Rotation fulcrum, 4 ... Apparatus main body, 5 ... Rotation support unit, 5d, 5d '... rotating fulcrum, 6 ... unit holding mechanism, 7 ... positioning member

Claims (4)

A plurality of photosensitive drums that carry a visible image, a belt unit that includes an intermediate transfer belt that is disposed opposite to the photosensitive drums to transfer and carry a visible image on each photosensitive drum, and a recording material on the surface side of the intermediate transfer belt in the image forming apparatus and a transfer member pressed, collectively transfers the visible image on the intermediate transfer belt to a recording material via,
While a side door for opening and closing a pivotally mounted Rutotomoni image forming apparatus main body on one side of the image forming apparatus main body,
Provided for this one side door, the transfer member is incorporated into one unit case, and the transfer member can be positioned in a positioning groove provided on the image forming apparatus main body side when the side door is closed. And a transfer unit that is held movably with the unit case with respect to the side door so that the transfer member can contact and separate from the intermediate transfer belt when the side door is closed,
The one side door opposite of the image forming apparatus main body openably provided against Rutotomoni image forming apparatus main body is provided on the other side and the belt unit to separate the photosensitive drum at the time of opening can drawer And an other side door having a large opening . The image forming apparatus according to claim 1.
An image forming apparatus, wherein the belt unit can be pulled out horizontally from the side of the main body of the image forming apparatus through the opening when the other side door is opened. The image forming apparatus according to claim 1.
An image forming apparatus, wherein a photosensitive unit including a photosensitive drum can be pulled out from a front side of the main body of the image forming apparatus. The image forming apparatus according to claim 3.
An image forming apparatus, wherein a photoconductor unit and a belt unit are arranged in a non-contact manner when the photoconductor unit or the belt unit is pulled out.

Images