JP2006293075A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus to/from which a unit constituting an image forming means can be attached/detached without reducing the strength of an apparatus main body. <P>SOLUTION: The image forming apparatus in which a sheet stored in a cassette is fed to the image forming means by a feeding means, to form an image on the recording medium is provided with a cassette opening 18 for loading/unloading the cassette 17 in/from an apparatus main body 1 and a moving means for moving a belt unit 25 which can be attached/detached to/from the apparatus main body 1 and is used for the formation of the image, to a position for forming the image and the position of the cassette opening 18. The image forming apparatus is constituted so that the belt unit 25 can be attachable/detachable to/from the apparatus main body through the cassette opening 18. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that feeds a recording medium stored in a cassette to an image forming unit by a feeding unit and forms an image on the recording medium.

  Electrophotographic recording type image forming apparatuses are widely used in copying machines, printers, and the like, and today, those capable of recording color images are widespread.

  In the case of obtaining a color image by the electrophotographic recording method, each toner image of yellow, magenta, cyan, and black is formed on each of the four photosensitive drums, and the toner images are superimposed and transferred onto the recording medium. It is common. Some color image forming apparatuses use an intermediate transfer member. This is configured by arranging four photosensitive drums in parallel and arranging an intermediate transfer belt so as to be in contact with each photosensitive drum. When forming an image, the color toner images are primarily transferred to an intermediate transfer member in a superimposed manner, and the primary transfer image is secondarily transferred to a transported recording medium to obtain a color image. As described above, the image forming apparatus using the intermediate transfer belt is unlikely to cause a registration error of the toner image and can obtain a high-quality image.

  In the image forming apparatus using the intermediate transfer belt as described above, the belt member needs to be maintained. For this reason, as disclosed in Japanese Patent Application Laid-Open No. H10-228707, there is one in which the transfer conveyance unit is held on a door to improve exchangeability. However, in this case, it is necessary to secure a large space necessary only for maintenance, and a substantial area occupied by the image forming apparatus is required.

  Therefore, as shown in Patent Document 2, there is an image forming case in which the entire image forming unit can be pulled out to the front surface of the apparatus main body, and thereafter the transfer belt unit can be maintained. However, the above-described configuration is considerably heavy to draw out the entire image forming unit. Therefore, it is necessary to provide a dedicated rail or the like for drawing out, and it is also necessary to strengthen the rigidity of the imaging case itself according to the weight.

  On the other hand, as disclosed in Patent Document 3, there is one in which a transfer belt is unitized and only this transfer belt can be pulled out and replaced on the front side of the apparatus. In this case, no extra space is required as a drawer space, and there is no problem due to the weight when the drawer is pulled out.

JP 2003-186370 A JP 09-179474 A Japanese Patent Laid-Open No. 06-186896

  However, when only the transfer belt can be pulled out from the front surface of the apparatus main body, the front plate constituting the frame of the apparatus main body needs to be significantly cut away. Therefore, the strength of the front side plate is reduced. Therefore, it is necessary to provide a reinforcing member for reinforcing the side plate in a limited space.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an image forming apparatus in which a unit constituting an image forming unit can be attached and detached without causing a reduction in strength of the apparatus main body. .

  A typical means in the present invention for solving the above-mentioned problems is an image forming apparatus in which a recording medium stored in a cassette is fed to an image forming means by a feeding means, and an image is formed on the recording medium. A cassette attaching / detaching opening for attaching / detaching the cassette to the apparatus main body, and a moving means for moving a unit used for image formation to a position for image formation and a position of the cassette attaching / detaching opening. And the unit is configured to be attachable to and detachable from the cassette main body through the cassette attaching / detaching opening.

  In the present invention, by attaching / detaching the unit to / from the apparatus main body through the cassette attaching / detaching opening, there is no need to provide a large notch on the side plate for attaching / detaching the unit, and it is possible to prevent the strength and accuracy of the side plate from being lowered. .

  Next, an image forming apparatus according to an embodiment of the present invention will be specifically described with reference to the drawings.

[First Embodiment]
{Overall configuration of image forming apparatus}
First, the overall configuration of the image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic sectional view of a color image forming apparatus.

  The image forming apparatus according to the present embodiment conveys a sheet as a recording medium upward from a feeding unit provided at the lower part of the apparatus main body 1 and forms an image formed by the image forming unit provided at the upper part of the feeding unit. After transferring in the transfer part, it is discharged to the discharge part.

  In the image forming means, four image forming stations are arranged substantially horizontally. In this embodiment, a yellow station Y, a magenta station M, a cyan station C, and a black station K are arranged from the left in FIG. Each station forms an image of each color toner by an electrophotographic recording method, and has the same configuration except that the color of the toner is different. Here, the configuration of the yellow station Y will be described briefly as an example.

  A primary charger 3, a developing device 4, and a cleaning device 5 are disposed around the photosensitive drum 2. A scanner unit 6 for irradiating a laser beam in accordance with an image signal is disposed above the photosensitive drum 2.

  Further, an intermediate transfer belt 7 which is an endless intermediate transfer member is in contact with the photosensitive drum 2 and is rotated by a driving roller 8 that drives the belt, and a secondary transfer inner roller 9 that transfers the multiple transferred images to the sheet. A primary transfer roller 10 is disposed at a position opposed to the photosensitive drum 2 with the intermediate transfer belt 7 interposed therebetween.

  When forming an image, the surface of the photosensitive drum 2 that rotates counterclockwise in FIG. 1 is uniformly charged by the primary charger 3, and a laser beam corresponding to the image signal is irradiated from the scanner unit 6 to electrostatically. A latent image is formed, and the latent image is developed with toner by the developing device 4 to be visualized.

  The toner image is primarily transferred to the intermediate transfer belt 7 by applying a bias to the primary transfer roller 10. Then, yellow, magenta, cyan, and black color toners formed by the respective image forming stations are superimposed on the intermediate transfer belt 7 and transferred to form a color image. This color image is transferred to the intermediate transfer roller 11 as the second intermediate transfer body by applying a bias in the secondary transfer portion, and further applied to both rollers 11 and 12 by applying a bias to the intermediate transfer roller 11 and the secondary transfer outer roller 12. The image is recorded after being secondarily transferred to the sheet P conveyed by the nip. The toner remaining on the intermediate transfer belt 7 after the toner image is transferred to the sheet is cleaned by the cleaning device 13.

  The sheet P onto which the toner image has been transferred in the secondary transfer unit is guided to the fixing device 14, and heat and pressure are applied to fix the toner image on the sheet P. Thereafter, the sheet P is discharged to the discharge unit 16 by the discharge roller pair 15. Is done.

  The sheet is fed to the image forming unit by a feeding unit. Here, the configuration of the sheet feeding means will be described. A sheet cassette 17 in which sheets P are stacked and stored is detachably attached to the lower part of the apparatus main body 1.

  A pickup roller 19 for feeding the uppermost sheet among the sheets stacked and stored in the sheet cassette 17 is provided in the vicinity of the mounting portion of the sheet cassette 17. Further, a pair of separation rollers composed of a feeding roller 20a and a separation roller 20b that separate and feed the sheets fed by the pickup roller 19 one by one, and the fed sheets are synchronized with the image forming timing to the secondary transfer unit. A registration roller pair 21 is provided for feeding in this manner. Thus, the sheets in the sheet cassette 17 are separated one by one and fed to the secondary transfer unit, and the toner image is transferred and fixed, and then discharged to the discharge unit 16.

  A cassette attaching / detaching opening 18 is formed in the lower part of the apparatus main body 1. The sheet cassette 17 is taken out by pulling the sheet cassette 17 from the cassette attaching / detaching opening 18 to the front side of the apparatus main body (front side in FIG. 1). Can do. In this way, by configuring the sheet cassette 17 to be pulled out to the front side of the apparatus main body 1 when loading sheets, it is not necessary to separately provide a cassette insertion / extraction space.

{Intermediate transfer unit attachment / detachment configuration}
The intermediate transfer belt 7 in this embodiment is unitized as a belt unit 25 together with the driving roller 8 and the secondary transfer inner roller 9 and is configured to be detachable from the apparatus main body 1. Next, the attachment / detachment configuration of the belt unit 25 will be described.

  First, the case where the intermediate transfer belt 7 of the present embodiment is removed from the apparatus main body 1 will be schematically described.

  In the image forming apparatus according to the present embodiment, when the belt unit 25 is removed from the apparatus main body 1, the sheet cassette 17 is first extracted from the apparatus main body 1, as shown in FIG. Next, as shown in FIG. 2B, the unitized intermediate transfer belt 7 is moved downward and removed from the apparatus main body 1 so as to be removed from the cassette attaching / detaching opening 18.

  That is, as shown in FIG. 3, a frame in which a front side plate 22 and a rear side plate 23 are erected is provided in the apparatus main body 1 of this embodiment, and a sheet cassette 17 and image forming means are supported by this frame. The A cassette attaching / detaching opening 18 for attaching / detaching the sheet cassette 17 is formed below the front side plate 22. Further, as shown in FIG. 4, an upper opening 24 for attaching the photosensitive drum 2 and the developing device 4 is provided on the upper portion of the front side plate 22. FIG. 4 is an explanatory front view of the front plate 22 in which the rear plate 23 is not shown.

  Here, the upper opening 24 is detachable from the photosensitive drum 2 and the developing device 4, but is not detachable from the belt unit 25. In order to make the belt unit 25 detachable from the upper opening 24, it is necessary to increase the size of the upper opening 24 as shown in FIG. For example, in the image forming apparatus of the present embodiment, it is necessary to enlarge the dimension D in FIG. 5 with a width of about 100 mm.

  If the size of the upper opening 24 is increased as described above, the belt unit 25 can be detached from the opening 24. However, on the other hand, the strength of the front side plate 22 is greatly reduced. If a reinforcing material is attached to reinforce this, the accuracy of the front side plate 22 may be reduced due to strain at the time of fastening.

  Therefore, in the present embodiment, the upper opening 24 of the front plate 22 is not enlarged, and the belt unit 25 can be attached and detached using the cassette attaching / detaching opening 18 provided in the lower portion of the front plate 22. That is, as shown in FIG. 6, the sheet cassette 17 is pulled out from the cassette attaching / detaching opening 18. Then, as shown in FIG. 7, the intermediate transfer belt 7 is lowered to the position of the cassette attaching / detaching opening 18, and the belt unit 25 is pulled out from the cassette attaching / detaching opening 18.

  For this purpose, the image forming apparatus of the present embodiment is provided with moving means for moving the belt unit 25 constituting the image forming means to the image forming position and the cassette attaching / detaching opening position.

{Belt unit moving means}
Next, the configuration of the moving means of the belt unit 25 according to this embodiment will be described. As shown in FIG. 8, the belt unit 25 can be mounted on the positioning tray 26. The positioning tray 26 is provided in the apparatus main body 1 and is configured to be movable in the vertical direction within the apparatus main body. As a result, the belt unit 25 supported by the positioning tray 26 can be moved between the image forming position and the cassette attaching / detaching opening position.

  In order to support the belt unit 25, one projection 26a1 is provided on the front side wall 26a of the positioning tray 26, and two projections 26b1 and 26b2 are provided on the rear side wall 26b. On the other hand, the front side wall and the rear side wall of the belt unit 25 are provided with fitting holes (not shown) into which the projections 26a1, 26b1, 26b2 can be fitted.

  For this reason, the belt unit 25 can be positioned and mounted on the positioning tray 26 as shown in FIG. 9 by fitting the fitting holes into the protrusions 26a1, 26b1, and 26b2. Then, after positioning the belt unit 25 on the positioning tray 26, the belt unit 25 can be fixed to the positioning tray 26 by attaching screws or the like to the projections 26a1 provided on the front side wall 26a of the positioning tray 26.

  The protrusions 26a1, 26b1, and 26b2 all protrude forward of the apparatus (in the direction of the cassette attaching / detaching opening 18). Therefore, by inserting / removing the belt unit 25 from the front of the apparatus (on the side of the cassette attaching / detaching opening 18), the fitting hole and the protrusions 26a1, 26b1, 26b2 can be fitted and detached.

  Here, the configuration for moving the positioning tray 26 up and down will be specifically described with reference to FIGS. 10 is an explanatory view of the moving means when the belt unit is at the image forming position, and FIGS. 11 and 12 are explanatory views of the moving means when the belt unit is at the cassette attaching / detaching opening position.

  The positioning tray 26 is supported by two shaft members 27a and 27b, and the shaft members 27a and 27b are rotatably connected to one ends of the link members 28a and 28b. The other ends of the link members 28a and 28b are rotatably attached to the front and rear side plates 22 and 23 by shaft portions 29a and 29b. 10 and 11, the shaft members 27a and 27b and the link members 28a and 28b are shown only on the rear side of the apparatus main body of the positioning tray 26. However, similar shaft members and link members are provided on the front side of the apparatus main body. It has been.

  Accordingly, the positioning tray 26 moves up and down as the link members 28a and 28b rotate about the shaft portions 29a and 29b. Further, since the link members 28a and 28b are parallel links, the vertical movement of the positioning tray 26 is a parallel movement. That is, the positioning tray 26 moves up and down while maintaining a substantially horizontal state, and the belt unit 25 attached thereto moves up and down while maintaining the posture when it is attached.

  In order to rotate the link members 28a and 28b, lift lever means 30 are provided. As shown in FIGS. 10 and 11, the lift lever means 30 is provided with L-shaped rotating members 30 a on the front side and the back side of the positioning tray 26. And one end side of each L-shaped rotation member 30a is connected by the rotation axis | shaft 30b, and the other end side is connected by the support part 30c.

  The rotating shaft 30b is rotatably supported by the front and rear side plates 22 and 23 constituting the frame. Furthermore, one end side of the rotating shaft 30b, that is, the front side of the apparatus main body protrudes toward the front side of the front plate 22, and a hand lever 30d is fixed to the protruding portion. Thereby, when the hand lever 30d is rotated, the L-shaped rotation member 30a is rotated about the rotation shaft 30b. Further, the lifting lever means 30 is configured so that it can be locked at a position where the hand lever 30d is erected (see FIG. 10) and at a position where the hand lever is tilted by 90 ° rotation (see FIG. 11). Has been.

  As shown in FIG. 10, when the hand lever 30d is raised, the support portion 30c supports the positioning tray 26 from below and supports the positioning tray 26 at the upper position. At this time, the belt unit 25 loaded on the positioning tray 26 is at the image forming position.

  On the other hand, as shown in FIG. 11, when the hand lever 30d is tilted, the rotating member 30a rotates around the rotating shaft 30b. At this time, the positioning tray 26 and the belt unit 25 loaded thereon are lowered by its own weight, and the belt unit 25 moves to the position of the cassette attaching / detaching opening 18. As a result, the belt unit 25 can be attached to and detached from the apparatus main body from the cassette attaching / detaching opening 18.

  When the hand lever 30d is rotated from the tilted state to the standing state, the belt unit 25 moves from the position of the cassette attaching / detaching opening 18 to the image forming position contrary to the above.

  Although the belt unit 25 is connected to a drive system (not shown) in the state of FIG. 10, for example, the drive system may be arranged on the side opposite to the moving direction of the belt unit 25 in a swinging manner. .

{Retraction mechanism of feeding means}
As described above, the belt unit 25 can move up and down in the apparatus main body. However, in the image forming apparatus of the present embodiment, the pickup roller 19 which is a part of the feeding unit is located in the moving area of the belt unit 25. Therefore, the image forming apparatus of the present embodiment is configured such that the pickup roller 19 can be retracted from the moving area. Next, the retracting configuration will be described with reference to FIGS.

  FIG. 13 is an explanatory perspective view showing the pickup roller 19 and the supply roller 20a of the supply means, and FIG. 14 shows a state in which the pickup roller 19 is rotated upward about the rotation axis of the separation roller 20a, that is, in a retracted state. Is shown.

  As shown in FIG. 13, the feed roller 20a is on the drive shaft 31 and is driven. The holder 32 has a pickup roller 19 and a bevel gear 33 attached thereto. Another bevel gear 34 is provided on a feeding frame (not shown).

  In addition, a rack gear 35 is provided in the sheet cassette 17, and the bevel gear 34 is rotated by the insertion / removal operation of the cassette 17. As a result, the bevel gear 33 meshing with the bevel gear 34 rotates, and the holder 32 and the pickup roller 19 integrated with the bevel gear 33 rotate around the drive shaft 31. When the holder 32 and the pickup roller 19 are rotated, the pickup roller 19 is rotated upward so as to be retracted from the moving region of the belt unit 25 as shown in FIG. Thus, since the pickup roller 19 is retracted in conjunction with the attaching / detaching operation of the cassette 17, it is not necessary to be aware of the retracting of the pickup roller 19. .

  Here, the relationship between the lifting and lowering operation of the belt unit 25 and the retraction of the pickup roller 19 will be described with reference to FIG. In FIG. 15, the movement of the belt unit 25 is shown at three positions in order to show the lifted state of the belt unit 25. The state before and after the pickup roller 19 is retracted is also shown.

  As shown in FIG. 15, when the pickup roller 19 is not retracted, the portion D in the figure interferes and the belt unit 25 cannot be raised or lowered. Therefore, in the present embodiment, as described above, the pickup roller 19 is retracted. Thereby, there is no need to change the movement locus of the belt unit 25. Therefore, the degree of freedom of the movement locus of the belt unit 25 is increased.

  By allowing the belt unit 25 to be raised and lowered from the image forming position to the cassette attaching / detaching opening position as described above, the belt unit 25 can be attached / detached from the cassette attaching / detaching opening 18. For this reason, it is not necessary to provide a large opening for attaching / detaching the belt unit to the frame, and it is possible to prevent the strength of the frame from being lowered.

  Further, since the cassette attaching / detaching opening 18 for attaching / detaching the belt unit 25 is provided at the lower part of the apparatus main body, the belt unit 25 is attached / detached at the lower part of the apparatus main body. Therefore, even if the belt unit 25 is pulled out from the apparatus main body 1, the center of gravity of the image forming apparatus does not increase. For this reason, the belt unit 25 can be attached and detached stably.

  Further, since the positioning tray 26 on which the belt unit 25 is mounted is a plate member positioned below the belt unit 25, an impact or the like is applied when the belt unit 25 is moved, and it is effective that the accumulated toner falls downward. To prevent. This has the effect of preventing the toner dropped from the belt unit 25 from adhering to the sheet when the sheet feeding means is located below the belt unit 25.

Other Embodiment
In the above-described embodiment, the positioning tray 26 on which the belt unit 25 is mounted is configured by a plate member. However, as shown in FIG. 16, the positioning tray 26 covers the entire lower part of the belt unit 25 and at least one around the periphery thereof. A standing wall 36 may be provided in the part.

  Thereby, an impact or the like is applied when the belt unit 25 is moved, and it is possible to effectively prevent the accumulated scattered toner and the like from being scattered to other units.

  Further, in the above-described embodiment, an example in which the toner image primarily transferred to the intermediate transfer belt 7 is transferred to the intermediate transfer roller 11 and transferred from the intermediate transfer roller 11 to the sheet P is exemplified. However, as shown in FIG. 17, an image forming apparatus that does not use the intermediate transfer roller 11 but directly transfers the toner image onto the sheet conveyed from the intermediate transfer belt 7 may be used. In that case, the sheet passes through the nip between the intermediate transfer belt 7 and the secondary transfer outer roller 12. At this time, depending on how the sheet enters the nip, an image defect related to transfer, for example, image disturbance due to discharge occurs.

  Therefore, as shown in FIG. 18, a guide member 37 for guiding the sheet from the registration roller pair 21 to the nip portion may be provided integrally with the positioning tray 26. In this way, the positional relationship between the secondary transfer inner roller 9 of the belt unit 25 positioned on the positioning tray 26 and the guide member 37 can be accurately guaranteed.

  In the above-described embodiment, the unit of the intermediate transfer belt 7 is exemplified as the unit to be attached / detached from the cassette attaching / detaching opening 18. However, the present invention is not limited to this. For example, instead of the intermediate transfer system, a sheet conveying belt that adsorbs and conveys a sheet is provided facing four photosensitive drums, and the conveying belt is unitized so as to be detachable from the apparatus main body. In such an apparatus, it is possible to attach and detach the conveyance belt unit from the cassette attaching / detaching opening 18 by making the conveying belt unit attachable to the positioning tray 26 described above.

1 is a schematic diagram of an image forming apparatus. It is explanatory drawing of the taking-out method of a belt unit. It is explanatory drawing of the front side board and rear side board which comprise a flame | frame. It is explanatory drawing of a front side board. It is explanatory drawing at the time of providing the opening for belt unit attachment / detachment in the front side board. It is explanatory drawing of the state which pulled out the cassette. It is state explanatory drawing which lowered the belt unit to the cassette attachment / detachment opening position. It is explanatory drawing of a positioning tray and a belt unit. It is explanatory drawing of a positioning tray and a belt unit. FIG. 6 is an explanatory diagram illustrating a configuration of a moving unit having a belt unit at an image forming position. FIG. 6 is an explanatory diagram illustrating a configuration of a moving unit in which a belt unit is set at a cassette attaching / detaching opening position. FIG. 6 is an explanatory diagram illustrating a configuration of a moving unit in which a belt unit is set at a cassette attaching / detaching opening position. It is explanatory drawing of the retraction | saving structure of a pick-up roller. It is explanatory drawing of the retraction | saving structure of a pick-up roller. It is explanatory drawing of the retraction | saving of a pick-up roller and the movement area | region of a belt unit. It is explanatory drawing which provided the standing wall around the positioning tray. It is explanatory drawing of the other example of an image forming apparatus. It is explanatory drawing of embodiment which provided the guide member in the positioning tray.

Explanation of symbols

P: Sheet 1: Main body 2 ... Photoconductor drum 3 ... Primary charger 4 ... Developing device 5 ... Cleaning device 6 ... Scanner unit 7 ... Intermediate transfer belt 8 ... Drive roller 9 ... Secondary transfer inner roller
10… Primary transfer roller
11… Intermediate transfer roller
12… Secondary transfer outer roller
13… Cleaning device
14… Fixing device
15… discharge roller pair
16… discharge section
17… sheet cassette
18… cassette attachment opening
19… Pickup roller
20a ... Feed roller
20b Separation roller
21… Registration roller pair
22… Front side plate
23… Rear side plate
24… Upper opening
25… Belt unit
26 ... Positioning tray
26a ... Front side wall
26a1… projection
26b ... rear side wall
26b1, 26b2 ... projection
27a, 27b ... Shaft member
28a, 28b ... Link member
29a, 29b ... Shaft
30… Lifting lever means
30a ... Rotating member
30b ... Rotating shaft
30c… support part
30d ... Hand lever
31… Drive shaft
32… Holder
33… bevel gear
34… bevel gear
35… Rack gear
36 Standing wall
37… Guide material

Claims (8)

In an image forming apparatus that feeds a recording medium stored in a cassette to an image forming unit by a feeding unit and forms an image on the recording medium.
A cassette attaching / detaching opening for attaching / detaching the cassette to / from the apparatus main body,
A moving means that is detachable from the apparatus main body and moves a unit used for image formation to a position for image formation and a position of the cassette attachment / detachment opening;
Have
An image forming apparatus, wherein the unit is configured to be attachable to and detachable from the cassette body through the cassette attaching / detaching opening. The image forming means develops a latent image formed on an image carrier with a developer and performs primary transfer onto an intermediate transfer member, and secondary transfer the primary transfer image onto the recording medium to form an image.
2. The image forming apparatus according to claim 1, wherein the unit detachable from the cassette attaching / detaching opening is the intermediate transfer member. The image forming apparatus according to claim 1, wherein the feeding unit is retractable from a moving area of the unit by the moving unit. 4. The image forming apparatus according to claim 3, wherein the retraction of the feeding unit is interlocked with an attaching / detaching operation of the cassette with respect to the apparatus main body. The image forming apparatus according to claim 1, wherein the moving unit moves the unit while maintaining a posture when the unit is mounted. The image forming apparatus according to claim 1, wherein the moving unit includes a plate member positioned below the unit. The image forming apparatus according to claim 1, wherein the unit is fixed to the moving unit, and the moving unit includes a guide member that guides the recording medium. The image forming apparatus according to claim 1, wherein the cassette attaching / detaching opening is provided at a lower portion of the apparatus main body.

Images