JP5435983B2 - Image forming apparatus and belt unit - Google Patents

Description

The present invention relates to an image forming apparatus using an electrophotographic system, such as a printer, a copying machine, and a facsimile. In particular, the present invention relates to an image forming apparatus including a belt unit that can be attached to and detached from the apparatus main body, and relates to a technique for improving the degree of freedom in design and the usability when the unit is attached and detached.

  Conventionally, a toner image formed on a photosensitive drum of a plurality of process cartridges is primarily transferred to an intermediate transfer belt in each primary transfer portion, and the toner image on the intermediate transfer belt is secondarily transferred to a recording medium in a secondary transfer portion. A color image forming apparatus is known.

  In such an image forming apparatus, the toner remaining on the intermediate transfer belt after the secondary transfer is removed by the intermediate transfer belt cleaning device and collected in a waste toner collecting container. A technique has been proposed in which the intermediate transfer belt cleaning device and the intermediate transfer belt are integrated as an intermediate transfer unit so that the intermediate transfer belt cleaning device and the intermediate transfer belt can be attached to and detached from the image forming apparatus main body (see, for example, Patent Document 1). Accordingly, waste toner can be collected without leaking, and maintenance work such as repair, inspection, and replacement of the intermediate transfer belt and the intermediate transfer belt cleaning device can be easily performed.

  An image forming apparatus having such an intermediate transfer unit is shown in FIGS. FIG. 23 is a cross-sectional view of an image forming apparatus according to a conventional example, and FIG. 24 is a perspective view of the image forming apparatus according to the conventional example. As shown in FIG. 23, the intermediate transfer unit 90 is arranged from one side of the image forming apparatus main body to the other side (for example, from left to right in FIG. 23). In the intermediate transfer unit 90, a plurality of process cartridges 93 are disposed below the intermediate transfer belt 91. Further, in the intermediate transfer unit 90, the intermediate transfer belt cleaning device 92 is integrally fixed to one end portion (left end portion in FIG. 23) of the intermediate transfer belt 91 so as to be arranged in parallel with the process cartridge 93. . As shown in FIG. 24, an opening 94 is provided on the side where the intermediate transfer belt cleaning device 92 is disposed (on the left side of the apparatus main body in the drawing) so that the intermediate transfer unit 90 can be pulled out. An opening / closing member 95 is provided so as to be opened and closed. Accordingly, the intermediate transfer unit 90 can be pulled out in the horizontal direction from the intermediate transfer belt cleaning device 92 side.

JP 2001-0775374 A

  However, in the image forming apparatus shown in FIGS. 23 and 24, the intermediate transfer unit 90 is fixed integrally with the intermediate transfer belt 91 in a state in which the intermediate transfer belt cleaning device 92 is bent. Therefore, in order to pull out the intermediate transfer unit 90 from the apparatus main body, it can be pulled out only from the intermediate transfer belt cleaning device 92 side so as not to interfere with the process cartridge 93. In other words, the intermediate transfer unit 90 in which the two units are integrated is an opening that naturally draws out the arrangement of the intermediate transfer belt cleaning device 92 that is the other unit relative to the intermediate transfer belt 91 that is one unit. The arrangement of the portion 94 is also determined. For this reason, the degree of freedom in design is limited by the arrangement of the intermediate transfer belt cleaning device 92.

  Further, while the intermediate transfer unit 90 is attached / detached from the opening 94 on the left side of the apparatus main body, the process cartridge 93 and the recording material cassette 96 need to be attached / detached in the direction of the solid arrow on the front side of the apparatus main body. Further, the fixing means 98 needs to be attached / detached in the direction of the broken line arrow by opening the opening / closing member 97 from the right side of the apparatus main body. Thus, the user is forced to access the inside of the image forming apparatus from various directions for maintenance, and there is room for improvement in terms of usability. Increasing the number of openings in the main body of the apparatus in this way is an obstacle to securing the rigidity of the frame, and since the number of opening and closing members increases, it is also a technical problem in realizing cost reduction and space saving. It has become.

  In view of such a background, the object of the present invention is to prevent the unit from being attached or detached and the position of the opening portion from being limited by the arrangement relationship of the two integrated units, and by other members in the apparatus. The attachment / detachment direction is not limited. Accordingly, it is an object to improve the usability from the viewpoint of improving the degree of freedom of design of the image forming apparatus and detachability of a unit that needs to be replaced.

  In order to solve the above problems, the present invention comprises the following arrangement.

(1) An image carrier that carries a toner image, an endless belt to which a toner image is transferred or transferred from the image carrier, and a plurality of belts that stretch the endless belt A detachable unit that is detachably attached to the main body of the image forming apparatus, and a first unit that includes a first tension member and a second unit that contacts the first unit; A guide member for guiding the detachable unit inserted from an opening for inserting the detachable unit into a main body, wherein the detachable unit holds the detachable unit. A handle portion, and the handle portion is housed in the detachable unit when the detachable unit is attached to the image forming apparatus main body, and the detachable unit is the image Projecting from said detachable unit is when detached from the forming apparatus main body, wherein the detachable unit is that by the second unit is moved relative to the first unit, taking the first posture and the second posture, the While the detachable unit is guided by the guide member and inserted into the main body of the image forming apparatus, the detachable unit is moved to the retracted state in conjunction with the change of the handle portion from the protruded state. An image forming apparatus that changes from one posture to the second posture.
(2) an endless belt that transfers a toner image from an image carrier or transports a recording medium to which the toner image is transferred, and a first unit that includes a plurality of stretching members that stretch the endless belt; A belt unit that is guided by a guide member provided in the main body of the image forming apparatus and is attached to and detached from an opening for attaching to and detaching from the main body of the image forming apparatus. A grip portion for holding the belt unit, the grip portion being housed in the belt unit when the belt unit is mounted on the image forming apparatus main body, and the belt unit being the image forming portion. Projecting from the belt unit when detached from the apparatus main body, the second unit moves relative to the first unit. Thus, the first posture and the second posture are taken, and the handle unit is housed from the protruding state while the belt unit is guided by the guide member and inserted into the image forming apparatus main body. The belt unit changes from the first posture to the second posture in conjunction with the change to the second posture.

  According to the present invention, the degree of freedom in designing the image forming apparatus can be improved, and usability can be improved from the viewpoint of detachability of a unit that needs to be replaced.

1 is a schematic sectional view of an image forming apparatus according to a first embodiment. Sectional view of intermediate transfer unit according to Embodiment 1 (A) Perspective view of an intermediate transfer unit according to Embodiment 1, (b), (c) Partial enlarged view of a grip portion of the intermediate transfer unit Top view of the intermediate transfer unit according to Embodiment 1. (A) Front view of intermediate transfer unit according to embodiment 1, (b) Partial enlarged view of transfer belt cleaning device of (a). FIG. 3 is a perspective view illustrating a mounting portion of an intermediate transfer unit according to the first embodiment. FIG. 6 is a perspective view illustrating the mounting operation of the intermediate transfer unit according to the first embodiment. FIG. 6 is a perspective view illustrating the mounting operation of the intermediate transfer unit according to the first embodiment. FIG. 4A is a perspective view illustrating a state in which the intermediate transfer unit according to the first embodiment is mounted, and FIG. (A) Perspective view showing the configuration of the intermediate transfer unit according to the first embodiment, (b) (a) Main part configuration diagram, (c) Partial enlarged view around the tension roller shaft (A) Perspective view showing the configuration of the intermediate transfer unit according to the first embodiment, (b) (a) main part configuration diagram of (a). (A) Perspective view showing the configuration of the intermediate transfer unit according to the first embodiment, (b) (a) main part configuration diagram of (a). Partial enlarged view showing an intermediate transfer unit and a mounting guide according to Embodiment 1. Sectional drawing which shows the completion state of mounting | wearing of the intermediate transfer unit which concerns on Example 1. FIG. (A) Perspective view showing the configuration of an intermediate transfer unit according to Example 2, (b) (a) Main part configuration diagram, (c) Partial enlarged view of rack and pinion, (d) Around tension roller shaft Partial enlarged view of (A) The perspective view which shows the structure of the intermediate transfer unit which concerns on Example 2, (b) The principal part block diagram of (a). (A) Perspective view showing the configuration of the intermediate transfer unit according to the second embodiment, (b) (a) Main part configuration diagram, (c) Partial enlarged view around the tension roller shaft 6A and 6B are diagrams illustrating a mounting operation of the waste toner recovery unit according to the third embodiment, where FIG. 5A is a diagram illustrating a state where the waste toner recovery unit is linear, FIG. 5B is a perspective view of FIG. The figure which shows the state which the toner collection unit rotated 45 degrees centering on the hinge part, (d) The perspective view of (c), (e) The figure which shows the state which the waste toner collection unit rotated 90 degrees centering on the hinge part, (F) Perspective view of (e) (A) Sectional drawing which shows mounting | wearing operation | movement of the waste toner collection | recovery unit based on Example 3, (b) Perspective view of (a). (A) Sectional drawing which shows mounting | wearing operation | movement of the waste toner collection | recovery unit based on Example 3, (b) Perspective view of (a). (A) Sectional drawing which shows mounting | wearing operation | movement of the waste toner collection | recovery unit based on Example 3, (b) Perspective view of (a). FIG. 10 is a diagram illustrating a mounting operation of the waste toner recovery unit according to the third embodiment, (a) a diagram illustrating a state in which the waste toner recovery unit is linear, and (b) a waste toner recovery unit having an elastic deformation portion at 45 °. The figure which shows the state bent to (c), (c) The figure which shows the state which the waste toner collection | recovery unit bent to 90 degrees by the elastic deformation part Sectional drawing of the image forming apparatus which concerns on a prior art example The perspective view of the image forming apparatus which concerns on a prior art example

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

  The image forming apparatus according to the present embodiment will be described with reference to FIGS. In the following description, first, the overall configuration of the image forming apparatus will be described with reference to FIG. Next, the configuration of the primary transfer unit will be described with reference to FIGS. Next, the operation of mounting the primary transfer unit on the apparatus main body will be described with reference to FIGS. Further, the relationship between the handle portion of the primary transfer unit and the transfer belt cleaning device will be described with reference to FIGS. Finally, the positioning of the primary transfer unit to the apparatus main body will be described with reference to FIGS. 7, 9, and 14.

[Entire configuration of image forming apparatus]
First, the overall configuration of the image forming apparatus will be described with reference to FIG. An image forming apparatus 100 shown in FIG. 1 includes four process cartridges arranged in parallel with an inclination with respect to the horizontal direction. Each of the process cartridges 7 (7a to 7d) includes an electrophotographic photosensitive drum 1 (1a to 1d) as one image carrier.

  An electrophotographic photosensitive drum (hereinafter referred to as “photosensitive drum”) 1 is rotationally driven clockwise in FIG. 1 by a driving member (not shown). Around the photosensitive drum 1, the following process means 2, 3, 4, 5, 6 that act on the photosensitive drum 1 are arranged in order according to the rotation direction. First, a charging roller 2 (2a to 2d) for uniformly charging the surface of the photosensitive drum 1 and a developing unit 4 (4a to 4d) for developing an electrostatic latent image using toner as a developer are arranged. A cleaning member 6 (6a to 6d) for removing the toner remaining on the surface of the photosensitive drum 1 after the transfer is disposed. Further, a laser unit is irradiated on the basis of image information to form an electrostatic latent image on the photosensitive drum 1, and four color developer (hereinafter referred to as “toner”) images on the photosensitive drum 1 (hereinafter referred to as “toner”). An intermediate transfer belt 5 on which toner images are transferred at once is disposed. Here, the photosensitive drum 1, the charging roller 2, the developing unit 4, and the cleaning member 6 are integrally formed as a cartridge to constitute a process cartridge 7 that can be attached to and detached from the mounting portion of the image forming apparatus.

  The intermediate transfer belt 5 is stretched around a driving roller 10, a tension roller 11, and a secondary transfer counter roller 33. Further, a primary transfer roller 12 (12a to 12d) is disposed inside the intermediate transfer belt 5 so as to face each of the photosensitive drums 1 (1a to 1d), and a transfer bias is applied by a bias applying unit (not shown). Is applied.

  In the toner image formed on the photosensitive drum 1, each photosensitive drum 1 rotates in the arrow Q direction, the intermediate transfer belt 5 rotates in the arrow R direction, and a positive bias is applied to the primary transfer roller 12. As a result, primary transfer is sequentially performed on the intermediate transfer belt 5. Then, the four-color toner images are conveyed to the secondary transfer unit 15 in a state where the intermediate transfer belt 5 is overlaid.

  On the other hand, the toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is removed by the cleaning member 6, and the removed toner is collected in a removed toner chamber in the photosensitive unit 26 (26a to 26d).

  In synchronism with these image forming operations, a sheet as a recording medium is conveyed by conveying means including a feeding device 13 and a pair of registration rollers 17. The feeding device 13 includes a feeding cassette 24 that stores the sheet S, a feeding roller 8 that feeds the sheet S, and a conveyance roller pair 16 that conveys the fed sheet S. The feeding cassette 24 is configured so that it can be pulled out toward the front of the apparatus in FIG. After the user pulls out the feeding cassette 24 and removes it from the apparatus main body, the sheet supply is completed by setting the sheet S and inserting it into the apparatus main body. The sheets S stored in the feeding cassette 24 are pressed against the feeding roller 8, separated one by one by the separation pad 9 (friction piece separation method), and conveyed by the conveying roller pair 16.

  Then, the sheet S conveyed from the feeding device 13 is conveyed to the secondary transfer unit 15 by the registration roller pair 17. In the secondary transfer unit 15, a positive bias is applied to the secondary transfer roller 18, whereby the four color toner images on the intermediate transfer belt 5 are secondarily transferred to the conveyed sheet S.

  The toner remaining on the intermediate transfer belt 5 after the secondary transfer to the sheet S is removed by the transfer belt cleaning device 23, and the removed toner passes through a waste toner conveyance path (not shown) and is on the left side of the device (FIG. 1 is collected in a waste toner collecting container 46 disposed on the left side.

  On the other hand, the fixing device 14 as a fixing unit applies heat and pressure to the toner image formed on the sheet S and fixes the toner image. The fixing belt 14a has a cylindrical shape and is guided by a belt guide member (not shown) to which heat generating means such as a heater is bonded. The fixing belt 14a and the pressure roller 14b form a fixing nip portion with a predetermined pressure contact force.

  The sheet S on which the unfixed toner image conveyed from the image forming unit is formed is heated and pressed at the fixing nip between the fixing belt 14a and the pressure roller 14b, and the unfixed toner image on the sheet S is heated. Is established. Thereafter, the fixed sheet S is discharged to the discharge tray 20 by the discharge roller pair 19.

[Configuration of primary transfer unit]
Next, the configuration of the intermediate transfer unit 101 as the primary transfer unit will be described with reference to FIGS. 2 is a schematic sectional view of the intermediate transfer unit 101, FIG. 3 is a perspective view of the intermediate transfer unit 101, FIG. 4 is a top view of the intermediate transfer unit 101, and FIG. 5 is a front view of the intermediate transfer unit 101.

  The intermediate transfer unit 101 is a detachable unit in which a transfer belt unit 25 that is a first unit and a transfer belt cleaning device 23 that is a second unit that operates in contact with the transfer belt unit 25 are integrally provided. The intermediate transfer unit 101 is detachably attached to the image forming apparatus 100 main body.

  Here, the transfer belt unit 25 includes an intermediate transfer belt 5 that is an endless belt that is stretched by a driving roller 10 that is a plurality of stretching members, a tension roller 11, and a secondary transfer counter roller 33. Further, the transfer belt unit 25 has four primary transfer rollers 12 (12 a to 12 d) provided at positions facing the respective photosensitive drums 1 via the intermediate transfer belt 5.

  As shown in FIG. 2, the transfer belt cleaning device 23 has a cleaning blade 31 as a cleaning member that contacts the intermediate transfer belt 5 and scrapes the residual toner on the intermediate transfer belt 5. The transfer belt cleaning device 23 includes a cleaning blade support plate 32 for maintaining the posture of the cleaning blade 31, and a blade pressure spring 34 for pressing the cleaning blade 31 against the intermediate transfer belt 5. Further, the transfer belt cleaning device 23 includes a screw 35 for sending the residual toner removed from the intermediate transfer belt 5 to a collection container.

  The transfer belt cleaning device 23 is provided so as to be able to swing with respect to the transfer belt unit 25 about an axis line in a direction orthogonal to the insertion direction. Specifically, as shown in FIGS. 3A and 4, the transfer belt cleaning device 23 supports shafts (hereinafter, tension roller shafts) 11 a and 11 b of the tension roller 11 with respect to the transfer belt unit 25. Is supported so as to be swingable. That is, the transfer belt cleaning device 23 is the tension that is the rotation center of the tension roller 11 that is located on the farthest side in the unit insertion direction (left side in FIG. 3A) among the plurality of stretching members of the transfer belt unit 25. It swings around the roller shafts 11a and 11b.

  The transfer belt unit 25 is provided with handle portions 47a and 47b. The handle portions 47a and 47b are centered on a rotation center 48a (the opposite side is not shown in FIG. 48b), and a torsion coil spring 49a (the opposite side is not shown in FIG. ) And FIG. 3C and the broken arrows (a) and (b) in FIG.

  As shown in FIG. 5A, the transfer belt cleaning device 23 with respect to the transfer belt unit 25 is mounted before (detached) from the image forming apparatus 100 main body and when it is completely mounted (mounted). The posture is different. With respect to the posture of the transfer belt cleaning device 23 with respect to the transfer belt unit 25, the posture indicated by a broken line in FIG. 5A is the first posture A at the start of insertion (before mounting: detached state), and FIG. The posture indicated by the solid line is the second posture B when the mounting is completed (after mounting: mounted state). By adopting such two postures, the height of the paper discharge tray can be lowered by the distance L shown in FIG. 5B, and the paper discharge stacking amount can be increased. Moreover, the height of the device itself can be kept low by taking two postures.

  As shown in FIG. 4, the transfer belt cleaning device 23 is provided with positioning bosses 36 a and 36 b for determining the posture when the transfer belt cleaning device 23 is attached to the main body of the image forming apparatus 100. The transfer belt unit 25 is provided with guided portions 37 a and 37 b when the intermediate transfer unit 101 is attached to the main body of the image forming apparatus 100. In FIG. 4, 10a and 10b are drive roller shafts, 10c and 10d are drive roller bearings attached to the drive roller shaft. The positioning bosses 36a and 36b of the transfer belt cleaning device 23, the guided portions 37a and 37b of the intermediate transfer unit 101, and the tension roller shafts 11a and 11b are guided by guide members in the main body of the image forming apparatus 100 described later. It is a guide member. These guided members are respectively provided on both sides in a direction orthogonal to the insertion direction of the intermediate transfer unit 101.

[Mounting operation of the primary transfer unit to the image forming apparatus body]
Next, a mounting operation when the intermediate transfer unit 101 is mounted on the main body of the image forming apparatus 100 will be described with reference to FIGS. FIG. 6 is a perspective view showing a mounting portion that is mounted on the main body of the image forming apparatus 100 of the intermediate transfer unit 101. FIG. 7 is a perspective view showing a state in which the intermediate transfer unit 101 is mounted on the image forming apparatus 100 main body. FIG. 8 is a perspective view illustrating a state in which the intermediate transfer unit 101 is inserted into the main body of the image forming apparatus 100 and the grip portions 47a and 47b begin to be stored, following FIG. FIG. 9 is a perspective view and a front view showing a state in which the intermediate transfer unit 101 is completely stored in the main body of the image forming apparatus 100.

  The intermediate transfer unit 101 is configured to be detachable from the image forming apparatus 100 main body. By adopting such a configuration, maintenance work such as repair, inspection, and replacement of the intermediate transfer belt 5 or the transfer belt cleaning device 23 can be performed with a simple operation. Can be improved.

  Further, in order to reduce the horizontal dimension of the main body of the image forming apparatus 100 and reduce the size of the main body of the image forming apparatus 100, the process cartridge 7 is disposed obliquely with respect to the horizontal direction as shown in FIG. Yes. In accordance with the arrangement of the process cartridge 7, the intermediate transfer unit 101 is also arranged obliquely with respect to the horizontal direction.

  The mounting direction of the intermediate transfer unit 101 with respect to the main body of the image forming apparatus 100 is an arrow F direction shown in FIG. The right side of the main body of the image forming apparatus 100 shown in FIG. 1 is the front side in the mounting direction of the intermediate transfer unit 101 as the primary transfer unit, and the left side in FIG.

  As shown in FIGS. 6 and 7, the image forming apparatus 100 is provided with an opening / closing member 38 that covers an opening 45 for inserting the intermediate transfer unit 101 into the main body of the image forming apparatus 100.

  When the intermediate transfer unit 101 is attached to the main body of the image forming apparatus 100, the opening / closing member 38 is first opened. As shown in FIG. 6, the secondary transfer counter roller 33 and the conveyance guide in the vicinity thereof are provided on the opening / closing member 38 and move together with the opening / closing member 38. The opening / closing member 38 forms a portion of the appearance surface of the image forming apparatus 100 main body. Further, when the opening / closing member 38 is opened, it is possible to remove the sheet S in which a jam such as a paper jam has occurred during conveyance from the opened opening 45, and the fixing device 14 can be attached and detached. The opening / closing direction of the opening / closing member 38 can be opened / closed in the vertical direction, but may be configured to be openable / closable in the horizontal direction.

  When the opening / closing member 38 is opened, the mounting portion 39 of the intermediate transfer unit 101 mounted on the main body of the image forming apparatus 100 is exposed inside the main body of the image forming apparatus 100 together with the conveyance path of the sheet S and the pair of registration rollers 17. .

  As shown by a dotted line in FIG. 6, the left side and the right side of the mounting portion 39 toward the opening 45 of the main body of the image forming apparatus 100 are located on the left side and the right side of the main body of the image forming apparatus 100 (the right side in FIG. 6). On the left side, mounting guides 40 and 41 extending obliquely upward are provided. The mounting guides 40 and 41 are guide members for guiding the intermediate transfer unit 101 inserted into the mounting unit 39 from the opening 45.

  Then, as shown in FIG. 7, the intermediate transfer unit 101 is guided while the positioning bosses 36a and 36b, the tension roller shafts 11a and 11b, and the guided portions 37a and 37b of the intermediate transfer unit 101 are guided by the mounting guides 40 and 41, respectively. Insert in the direction of arrow F. Thereafter, during the insertion, as shown in FIG. 8, the grip portions 47a and 47b of the intermediate transfer unit 101 abut against the cover of the image forming apparatus 100 main body, and rotate in the directions of arrows (c) and (d) in the figure. And begins to be stored in the intermediate transfer unit 101. By continuing the insertion, the grip portions 47 a and 47 b are sandwiched between the mounting guides 40 and 41 and are completely accommodated in the intermediate transfer unit 101. Finally, as shown in FIG. 9, after the intermediate transfer unit 101 is inserted to a predetermined insertion position inside the main body of the image forming apparatus 100, the opening / closing member 38 is closed to complete the mounting of the intermediate transfer unit 101.

[Relationship between primary transfer unit handle and transfer belt cleaning device]
A configuration in which the transfer belt cleaning device 23 swings in conjunction with the rotation of the grip portions 47a and 47b of the intermediate transfer unit 101 will be described in detail with reference to FIGS.

  FIG. 10A is a perspective view before the intermediate transfer unit 101 is mounted, and FIG. 10B is a swing operation of the grip portions 47a and 47b and the transfer belt cleaning device 23 for convenience of explanation. It is the figure which removed from FIG. The handle portion 47b has a flexible wire 52 locked to the boss portion 47bp. The other end of the wire 52 is locked to a wire holding portion 53 provided in the transfer belt cleaning device 23 via a wire guide 54 provided in a part of the frame of the transfer belt unit 25 and an opening 51 of the frame. Has been. Before being attached to the main body of the image forming apparatus 100, the handle portion 47 b receives an urging force as described above, and rotates and protrudes outside the intermediate transfer unit 101. The rotation amount of the grip portion 47b is regulated by the partial rotation stop portion 47bf coming into contact with a part of the frame of the transfer belt unit 25. On the other hand, the wire 52 is set to have such a length as to be in the posture A described above when the handle portion 47b protrudes most. That is, with the protrusion of the handle 47b, the transfer belt cleaning device 23 connected by the wire 52 is pulled and maintained and restrained in the posture A around the tension roller shaft 11b. As shown in FIG. 10 (c), the transfer belt cleaning device 23 has a rib-shaped rotation restricting portion 50m formed on a part of the frame of the transfer belt unit 25 and a rotation restricting portion 50n guided by the rib-like rotation restricting portion 50n. The configuration is such that the amount of movement is a desired amount. The rotation restricting portion 50n is provided in the transfer belt cleaning device 23.

  Next, the posture of the transfer belt cleaning device 23 when the grip portions 47a and 47b are housed in the intermediate transfer unit 101 will be described. FIG. 11 is a state in the middle of mounting the intermediate transfer unit 101 to the image forming apparatus 100 main body, and FIG. 12 is a view after the mounting is completed. (A) and (b) in the drawing are a perspective view of the intermediate transfer unit 101 at each timing and a diagram of related elements, as in FIG.

  As described above, when the intermediate transfer unit 101 is mounted on the main body of the image forming apparatus 100, the grip portions 47a and 47b start to be accommodated while being in contact with the main body of the image forming apparatus 100. That is, as shown in FIG. 11A, the intermediate transfer unit 101 starts to be stored while being rotated in the directions indicated by arrows (e) and (f). At the same time, when the handle portion 47b is rotated in the direction of the arrow (K) in the drawing, the tension of the wire 52 connected to the handle portion 47b is weakened, and the transfer belt cleaning device 23 has its own weight, so that the transfer belt cleaning device 23 in FIG. Try to start swinging as shown by the arrow (c).

  Further, when the intermediate transfer unit 101 is inserted into the main body of the image forming apparatus 100, the grip portions 47a and 47b are completely inserted into the intermediate transfer unit 101 in FIG. Stored. At this time, as shown in FIG. 12B, the handle 47b is rotated in the direction of the broken line arrow (n) in the figure, the tension of the wire 52 is lost, and the transfer belt cleaning device 23 is further indicated by the arrow (s). Oscillate in the direction, and the oscillation is stopped by the rotation restricting portions 50m and 50n described above. At this time, the swing is not restricted in the restriction of the rotation restricting portions 50m and 50n.

  As described above, by adopting a configuration in which the transfer belt cleaning device 23 swings with respect to the transfer belt unit 25, the size of the device can be reduced. However, on the other hand, as shown in FIG. 13, the swing amount K of the transfer belt cleaning device 23 becomes larger than the entrance width J of the mounting guides 40 and 41. For this reason, when the user starts to insert the intermediate transfer unit 101 into the main body of the image forming apparatus 100, the insertion position is not fixed and it may be difficult to insert. Of course, measures to enlarge the entrances themselves of the mounting guides 40 and 41 or to enlarge the chamfered portion can be considered. However, there is a concern that the space necessary for the intermediate transfer unit 101 and the fixing device 14 that originally play a large role in image formation may be affected, or the apparatus itself may become large.

  On the other hand, as described above, the transfer belt cleaning device 23 swings with respect to the transfer belt unit 25, and the swinging of the grip portions 47a and 47b and the transfer belt cleaning device 23 is linked. By doing so, it is possible to realize the configuration of the image forming apparatus that ensures the usability when the unit is mounted without increasing the space occupied by the conventional mounting guides 40 and 41 and the intermediate transfer unit 101.

[Positioning of the primary transfer unit to the main unit]
Next, the positioning of the intermediate transfer unit 101 with respect to the main body of the image forming apparatus 100 will be described in more detail with reference to FIGS. 7, 9, and 14.

  In the following description, the positioning of the intermediate transfer unit 101 on the front side of the main body with respect to the mounting guide 40 on the front side of the sheet of FIG. On the back side of the main body of the image forming apparatus 100 and the intermediate transfer unit 101 (not shown) on the back side of the paper surface in FIG. The intermediate transfer unit 101 is mounted without causing an inclination between the front and back sides of the image forming apparatus 100 main body in the drawing.

  Before the intermediate transfer unit 101 is mounted, the transfer belt cleaning device 23 with respect to the transfer belt unit 25 has the posture A in FIG. 5 in accordance with the rotation and protrusion of the grip portions 47a and 47b as described above. Take. For this reason, as shown in FIG. 7, it takes the 1st attitude | position on a substantially straight line so that a unit lower surface may become a substantially plane.

  As shown in FIG. 9B, the mounting guide 40 provided in the mounting portion 39 of the main body of the image forming apparatus 100 has a first guide portion 40b and a second guide portion in order from the upstream side in the insertion direction to the downstream side. 40d and a third guide portion 40f. The three guide portions are formed such that the width in which the mounting guide 40 sandwiches each guided member narrows stepwise toward the downstream side in the insertion direction. Among these, the second guide portion 40d is narrower than the first guide portion 40b and has a width for fitting the tension roller shaft 11a. The third guide portion 40f is narrower than the second guide portion 40d and has a width for fitting the positioning boss 36a.

  When the intermediate transfer unit 101 is mounted on the main body of the image forming apparatus 100, first, the positioning boss 36a of the transfer belt cleaning device 23 is aligned with the inlet 40a of the mounting guide 40 as shown in FIG. Then, when the intermediate transfer unit 101 is inserted in the direction of the arrow F with the positioning boss 36 a along the lower surface of the first guide portion 40 b of the mounting guide 40, the tension roller shaft 11 a is then moved to the first guide of the mounting guide 40. Guided by the portion 40b. When the intermediate transfer unit 101 is further pushed in the direction of arrow F, the guided portion 37 a of the transfer belt unit 25 is guided by the first guide portion 40 b of the mounting guide 40.

  If the intermediate transfer unit 101 is continuously pushed in the direction of arrow F, the positioning boss 36a of the transfer belt cleaning device 23 reaches the bent portion 40e of the second guide portion 40d of the mounting guide 40. Thereafter, as shown in FIG. 9B, the positioning boss 36a is guided by the second guide portion 40d of the mounting guide 40, and the transfer belt cleaning device 23 gradually swings around the tension roller shaft 11a. Start changing. At this time, since the grip portions 47a and 47b are already accommodated in the intermediate transfer unit 101 and the swinging of the transfer belt cleaning device 23 is not restricted, the posture change of the transfer belt cleaning device 23 by the mounting guide 40 is changed. There is no hindrance.

  Then, immediately before the intermediate transfer unit 101 is completely attached to the main body of the image forming apparatus 100, as shown in FIG. 14, the driving roller bearing 10c attached to the driving roller shaft 10a is locked to the main body of the image forming apparatus 100. It reaches a position in contact with the lever 43.

  The lock lever 43 is provided on the main body side of the image forming apparatus 100 and rotates around the rotation center 43a. The lock lever 43 is biased in the direction of arrow G by the lock lever spring 44 around the rotation center 43a.

  If the intermediate transfer unit 101 is further pushed in the direction of arrow F after the drive roller bearing 10c reaches a position where it contacts the lock lever 43, the lock lever 43 receives a force from the drive roller bearing 10c and is in a direction opposite to the arrow G direction. Retract while rotating. When the drive roller bearing 10c passes the apex 43b of the lock lever 43, the lock lever 43 rotates in the direction of arrow G along the drive roller bearing 10c by the urging force of the lock lever spring 44.

  When the driving roller bearing 10c hits the positioning portion 42 provided in the main body of the image forming apparatus 100, the intermediate transfer unit 101 stops and the mounting is completed. The lock lever 43 fixes the intermediate transfer unit 101 to the main body of the image forming apparatus 100 while pressing the driving roller bearing 10 c against the positioning portion 42.

  At this time, the tension roller shaft 11a reaches the second guide portion 40d of the mounting guide 40 and is in a fitted state in a direction substantially perpendicular to the mounting direction of the intermediate transfer unit 101. Thereby, the position of the transfer belt unit 25 in the intermediate transfer unit 101 is determined. Further, the transfer belt cleaning device 23 is brought into a fitted state when the positioning boss 36 a reaches the third guide portion 40 f of the mounting guide 40. As a result, the transfer belt cleaning device 23 stops swinging about the tension roller shaft 11a as the center of rotation, and finishes changing to a second posture different from the first posture before mounting, and FIG. The position is determined as shown in FIG. As described above, the transfer belt unit 25 and the transfer belt cleaning device 23 constituting the intermediate transfer unit 101 are each positioned in the main body of the image forming apparatus 100 by the mounting guide 40 (41).

  As described above, the intermediate transfer unit 101 is integrated with the transfer belt unit 25 so that the transfer belt cleaning device 23 can swing. As a result, the posture of the transfer belt cleaning device 23 with respect to the transfer belt unit 25 changes in accordance with the attachment guides 40 and 41 in the intermediate transfer unit 101 during the attachment process. For this reason, the mounting / removal direction of the intermediate transfer unit 101 and the position of the opening are not limited by the arrangement relationship between the transfer belt cleaning device 23 and the transfer belt unit 25 which are two integrated units. Further, the attaching / detaching direction of the intermediate transfer unit 101 is not limited by a member such as a process cartridge in the apparatus. Thereby, the freedom degree of design improves.

  Further, by using the intermediate transfer unit 101 in which the transfer belt cleaning device 23 is swingably integrated with respect to the transfer belt unit 25, the intermediate transfer unit 101 can be pulled out from the transfer belt unit 25 side. As a result, the opening / closing member 38 of the opening for attaching / detaching the unit can be used as an opening / closing member for jamming the sheet S and an opening / closing member for replacing the fixing device.

  In the above-described embodiment, four process cartridges that can be attached to and detached from the image forming apparatus main body are used. However, the number of the process cartridges is not limited, and may be set as necessary. Further, the guide member is not limited to the rail shape as in the above-described form, and may be another member that changes the posture of the second unit relative to the first unit, such as a protrusion inside the main body.

  Further, in the above-described embodiment, a process including a photosensitive drum, and a charging unit (charging roller 2), a developing unit (developing unit 4), and a cleaning unit (cleaning member 6) as process units acting on the photosensitive drum. A cartridge was illustrated. However, the process cartridge is not limited to this, and may be a process cartridge integrally including any one of a charging unit, a developing unit, and a cleaning unit in addition to the photosensitive drum.

  In the first embodiment, the configuration in which the transfer belt cleaning device 23 is restrained from swinging and its posture using the wire 52 with respect to the transfer belt unit 25 is presented as an embodiment. On the other hand, the grip portions 47a and 47b and the transfer belt cleaning device 23 can be interlocked by a rack and pinion (rack and pinion) mechanism. The configuration in this case will be described with reference to FIGS.

  15 to 17 are similar to FIGS. 10 to 12, using a mechanism including racks 55 a and 55 b and a pinion 56, and in conjunction with the rotation of the grip portions 47 a and 47 b of the intermediate transfer unit 101, the transfer belt cleaning device. The configuration in which the 23 swings will be described in detail.

  FIG. 15A is a perspective view before the intermediate transfer unit 101 is mounted, and FIG. 15B is a diagram that does not relate to the operation relationship between the grip portions 47a and 47b and the transfer belt cleaning device 23 for convenience of explanation. It is the figure removed from Fig.15 (a). FIG. 15C is a partially enlarged view showing the pinion 56. FIG. 15D is a partially enlarged view showing the relationship between the cam portion 55ba of the rack 55b and the boss portion 23a which is a guided portion of the transfer belt cleaning device 23. There is a rack holding portion 57 provided at a part of the frame of the transfer belt unit 25, and racks 55a and 55b are attached together with the pinion 56 in the direction of the solid arrow in FIG. The rack 55a is urged in the direction of the broken line arrow (f) in FIG. 15 (b) by a compression spring 58 attached to a spring holding part 57a formed in a part of the rack holding part 57. The rack 55a stops moving in the direction of the arrow until the end of the hole 55bc of the other pair of racks 55b contacts the tension roller shaft 11b. Then, the cam portion 55ba of the rack 55b has a relationship as shown in FIG. 15D with the boss portion 23a which is a guided portion of the transfer belt cleaning device 23, and the transfer belt cleaning device 23 is the first in FIG. Take posture A.

  Next, the posture of the transfer belt cleaning device 23 when the grip portions 47a and 47b are housed in the intermediate transfer unit 101 will be described. 16 is a state in the middle of mounting the intermediate transfer unit 101 to the main body of the image forming apparatus 100, and FIG. 17 is a view after the mounting is completed. (A) and (b) in the figure are a perspective view of the intermediate transfer unit 101 at each timing and a diagram of related elements, as in FIG.

  As described above, when the intermediate transfer unit 101 is mounted on the main body of the image forming apparatus 100, the grip portions 47a and 47b start to be stored as follows. That is, the grip portions 47a and 47b are rotated in the directions of arrows (s) and (s) in the drawing with respect to the intermediate transfer unit 101 as shown in FIG. It begins to be stored while. Then, the handle portion 47b rotates in the direction of the broken line arrow (so) in the drawing and comes into contact with the contact portion 55ab provided in the rack 55a. The rack 55a resists the urging force of the compression spring 58, while FIG. It begins to slide in the direction of the solid arrow in (b). Further, when the intermediate transfer unit 101 is inserted into the main body of the image forming apparatus 100, the grip portions 47a and 47b are completely accommodated in the intermediate transfer unit 101 in FIG. At this time, as shown in FIG. 17B, the rack 55a receives the force from the handle portion 47a, slides in the direction of arrow (t), the pinion 56 rotates in the direction of arrow (h), 55b slides in the direction of the arrow. The cam portion 55ba of the rack 55b has a relationship as shown in FIG. 17C with the boss portion 23a which is a guided portion of the transfer belt cleaning device 23, and the transfer belt cleaning device 23 is the second portion of FIG. The posture B is taken.

  As described above, the movement range of the transfer belt cleaning device 23 is regulated by the cam portion 55ba of the rack 55b (the amount M in the direction of the arrow in the figure), so that the swing range is defined. However, it can swing freely within the regulations. Therefore, as in the first embodiment, the intermediate transfer unit 101 can be accommodated in the image forming apparatus 100 main body along the shape of the mounting guides 40 and 41 in the image forming apparatus 100 main body. The present embodiment can be realized without any change from the first embodiment except for the swing configuration of the transfer belt cleaning device 23 with respect to the transfer belt unit 25. Specifically, the configuration of the main body and the image forming operation of the image forming apparatus 100, the method of attaching and detaching the transfer belt unit 25 to and from the main body of the image forming apparatus 100, positioning, and the like are realized without any change from the first embodiment. Is possible. For this reason, those explanations are omitted.

  In the first and second embodiments, the image forming apparatus 100 is configured such that the transfer belt cleaning device 23 swings with respect to the transfer belt unit 25. The image forming apparatus has been described as an image forming apparatus that forms a recorded image using the intermediate transfer unit 101 that is interlocked with the grip portions 47a and 47b and whose swing amount is regulated. However, the present invention is not limited to the intermediate transfer unit 101.

  For example, the present invention can also be applied to a waste toner collection container 46 collected by the transfer belt cleaning device 23. Hereinafter, an embodiment in this case will be described with reference to FIGS. Hereinafter, as in the second embodiment, description of the main body configuration and the image forming operation of the image forming apparatus 100 is omitted.

  FIG. 18 shows a waste toner collecting unit 64 including a first container 60 and a second container 61. In the combinations of (a), (b), (c), (d), (e), and (f), the waste toner collection unit 64 is rotated straight from the first container 60 and the second container 61, respectively. It shows a state in which the posture is changed by rotating 45 ° and 90 ° around the hinge portion 63 that is movably connected. In the drawing, (a), (c), and (e) are front views, and (b), (d), and (f) are perspective views.

  The waste toner collection unit 64 collects the waste toner discharged from the intermediate transfer unit 101 via the transfer belt cleaning device 23 and a conveyance path (not shown). The first container 60 and the second container 61 are connected in the container, and the waste toner can be collected until both the volumes of the first container 60 and the second container 61 are filled.

The waste toner collecting unit 64 is provided with a flexible handle 62 that connects the first container 60 and the second container 61. The handle can be moved by the handle guide portions 60c, 61c, 61d provided in the first container 60 and the second container 61 without being detached as shown in FIG. 18 when the waste toner collecting unit 64 is attached or detached. It can be done. When the handle 62 is pulled during detachment, FIG. 18 (a), the the tape path over portion 62a of the portion of the tapered shape of the handle 62 as shown in FIG. 18 (b), the tapered portion 61e and the engagement of the second container The waste toner collecting unit 64 is maintained in a straight line.

  19 to 21 show how the waste toner collecting unit 64 is stored in the main body of the image forming apparatus 100. FIG. 19 to 21 show that the waste toner collecting unit 64 is linear and the hinge portion 63 is formed so as to correspond to FIGS. 18A, 18B, 18C, 18D, 18E, and 18F. It is a figure when rotating at 45 degrees and 90 degrees to the center (oscillating). 19 to 21, (a) is a front view of the periphery, and (b) is a perspective view of the periphery.

  A part 65 of the main body of the image forming apparatus 100 is provided with mounting guides 67 and 68 for the waste toner collecting unit 64 as in the previous embodiment. On the other hand, the first container 60 and the second container 61 are formed with positioning bosses 60a and 60b and 61a and 61b which are guided portions and positioning portions. For the sake of simplicity, the mounting guides 67 and 68 are only located at the front and back in the figure within the image forming apparatus 100 main body, and the functions are the same. I will explain.

  As shown in FIGS. 19A and 19B, the mounting guide 67 provided in a part 65 of the main body of the image forming apparatus 100 is a first guide portion in order from the upstream side to the downstream side in the insertion direction. 67b and a second guide part 67d. The two guide portions are formed such that the width of the mounting guide 67 sandwiching each guided member becomes narrower stepwise toward the downstream side in the insertion direction. Among these, the second guide portion 67d is narrower than the first guide portion 67b, and has a width for fitting the positioning bosses 61a and 61b which are positioning portions.

  When the waste toner collecting unit 64 is mounted on the main body of the image forming apparatus 100, first, the positioning boss 61a of the second container 61 is aligned with the inlet portion 67a of the mounting guide 67, as shown in FIG. Then, when the waste toner collection unit 64 is inserted in the direction of the arrow N in the drawing with the positioning boss 61a along the lower surface of the first guide portion 67b of the mounting guide 67, first, the positioning boss of the first container 60 is first. 60 a is guided by the first guide portion 67 b of the mounting guide 67.

  When the waste toner collecting unit 64 is continuously pushed in the direction of arrow N, the positioning boss 61a of the waste toner collecting unit 64 reaches the bent portion 67e before the second guide portion 67d of the mounting guide 67. Thereafter, as shown in FIG. 20, the positioning boss 61 a is guided by the second guide portion 67 d of the mounting guide 67, and the waste toner collection unit 64 gradually swings around the hinge portion 63 and starts to change its posture.

  Next, when reaching FIG. 21, the positioning boss 61 a reaches the second guide portion 67 d of the mounting guide 67, and is fitted in a direction substantially parallel to the mounting direction of the waste toner collecting unit 64. Thereby, the position of the second container 61 in the waste toner collecting unit 64 is determined. Further, the first container 60 is brought into a fitted state at the positioning portion 67f when the positioning boss 60a reaches the first guide portion 67b of the mounting guide 67. As a result, the first container 60 stops swinging about the hinge portion 63 as the center of rotation, has finished changing to the second posture different from the first posture before mounting, and is positioned as shown in FIG. Is decided. As described above, the first container 60 and the second container 61 constituting the waste toner collecting unit 64 are each positioned in the main body of the image forming apparatus 100 by the mounting guide 67 (68).

  By adopting such a unit configuration, even in a space where there is another unit 66 in the vicinity of the image forming apparatus 100 main body and a simple shape such as a rectangular parallelepiped cannot be secured, the space is effectively utilized, Miniaturization can be realized. And the structure which was excellent also in the detachability of the rocking | swiveling unit can be taken.

[Other Embodiments of Connection between First Container and Second Container]
Further, in relation to the present embodiment, as shown in FIG. 22, the same effect can be obtained by forming an elastic deformation portion 70 having a bellows structure between the first container 60 and the second container 61. When the second container 61 is rotated (oscillated) by 45 ° with respect to the first container 60, the second container 61 passes through the point (te) as shown in FIG. The axis in the direction orthogonal to the insertion direction is the central axis 69. When the second container 61 is rotated (oscillated) by 90 °, the axis passes through the point (G) as shown in FIG. 22C and is orthogonal to the direction in which the waste toner collection unit 64 is inserted. Becomes the central axis 69.

  As described above, the printer is exemplified as the image forming apparatus in the above-described embodiment. However, the present invention is not limited to this, and other image forming apparatuses such as a copying machine and a facsimile machine, or a combination of these functions. Other image forming apparatuses such as multifunction peripherals may also be used. Further, the image forming apparatus has been exemplified in which an intermediate transfer belt is used, toner images of respective colors are sequentially transferred onto the intermediate transfer belt, and the toner images carried on the intermediate transfer belt are collectively transferred to a recording medium. However, the present invention is not limited to this. An image forming apparatus that uses a recording medium conveyance belt as an endless belt and sequentially superimposes and transfers toner images of each color onto a recording medium carried on the recording medium conveyance belt. The same effect can be obtained by applying the present invention to these image forming apparatuses.

S sheet 1 photosensitive drum 2 charging roller 3 scanner unit 4 developing unit 5 intermediate transfer belt 6 cleaning member 7 process cartridge 12 primary transfer roller 18 secondary transfer roller 23 transfer belt cleaning device 25 transfer belt unit 26 photoconductor unit 31 cleaning blade 32 Blade support plate 33 Secondary transfer counter roller 46 Waste toner collection container 47a, 47b Handle portion

Claims (12)

An image carrier for carrying a toner image;
A first unit comprising: an endless belt for transferring a toner image from the image carrier or conveying a recording medium to which the toner image is transferred; and a plurality of stretching members for stretching the endless belt ; A detachable unit that is detachably mounted on the image forming apparatus main body, and a second unit that contacts the first unit;
A guide member for guiding the detachable unit inserted from an opening for inserting the detachable unit into the image forming apparatus main body;
An image forming apparatus having
The detachable unit includes a handle for holding the detachable unit. The handle is accommodated in the detachable unit when the detachable unit is mounted on the image forming apparatus main body, and the detachable unit is the image. When detached from the forming apparatus main body, it protrudes from the detachable unit,
The detachable unit by the second unit is moved relative to the first unit, taking the first posture and the second posture,
The attachment / detachment unit is moved in the middle of being inserted into the image forming apparatus main body by being guided by the guide member, and the attachment / detachment unit is moved in conjunction with the change from the protruded state to the accommodated state. An image forming apparatus that changes from a first posture to the second posture.   The second unit is integrally provided to be swingable with respect to the first unit about an axis perpendicular to a direction in which the detachable unit is inserted into the image forming apparatus main body. The image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein the second unit is a cleaning unit including a cleaning member that contacts the endless belt and cleans toner of the endless belt. 4. The first unit and the second unit, the guide member or the image forming apparatus according to any one of claims 1 to 3, characterized in that positioning in each said image forming apparatus main body is made by the body The image forming apparatus described in the item. When said detachable unit is inserted into the image forming apparatus main body from the opening, according to claim 1 to claim 4 wherein said than the first unit the second unit is being inserted into previously The image forming apparatus according to claim 1. The second unit swings around the rotation center of the stretching member located on the innermost side in the direction in which the detachable unit is inserted among the plurality of stretching members of the first unit. The image forming apparatus according to claim 1 , wherein the image forming apparatus is an image forming apparatus. An endless belt for transferring a toner image from an image carrier or conveying a recording medium to which a toner image is transferred;
A first unit comprising a plurality of stretching members that stretch the endless belt;
A second unit that contacts the first unit;
A belt unit that is guided by a guide member provided in the image forming apparatus main body and is attached to and detached from an opening for attaching to and detaching from the image forming apparatus main body,
A handle for holding the belt unit;
The grip portion is housed in the belt unit when the belt unit is attached to the image forming apparatus main body, and protrudes from the belt unit when the belt unit is detached from the image forming apparatus main body.
When the second unit moves relative to the first unit, the first posture and the second posture are taken,
The first posture is interlocked with the change of the grip portion from the protruded state to the retracted state while the belt unit is guided by the guide member and inserted into the image forming apparatus main body. The belt unit is changed from the second posture to the second posture. The second unit is integrally provided to be swingable with respect to the first unit about an axis perpendicular to a direction in which the belt unit is inserted into the image forming apparatus main body. The belt unit according to claim 7. The belt unit according to claim 7 or 8, wherein the second unit is a cleaning unit including a cleaning member that contacts the endless belt and cleans toner of the endless belt. The first unit and the second unit are respectively positioned on the image forming apparatus main body by the guide member or the image forming apparatus main body. The belt unit according to item. 11. The second unit is inserted before the first unit when the belt unit is inserted into the image forming apparatus main body from the opening. The belt unit according to any one of the above. The second unit swings around the rotation center of the stretching member located on the innermost side in the direction in which the belt unit is inserted among the plurality of stretching members of the first unit. The belt unit according to any one of claims 7 to 11, wherein the belt unit is characterized in that

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