JP2000147860A - Image forming device and image forming unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and stably hold a plurality of image forming units at normal positions. SOLUTION: This image forming device is provided with a plurality of image forming units 21 equipped with a developing device 31, an electrifier 28 and a photoreceptor 27, a carriage 22 for holding plural image forming units 21 on a printer body 1 freely attachably/detachably and rotating/moving these units 21 to the image forming position 25 or the other position, a laser exposing means 44 for exposing the photoreceptor 27 at the image forming position 25, an intermediate transfer belt 4 for accepting the toner image formed on the photoreceptor 27 at the image forming position 25 and forming the color image, an output shaft 70 engaged with at least one side of the axial end part of the photoreceptor 27 from the axial direction of the photoreceptor 27 at the image forming position 25 and positioning the photoreceptor 27 to the normal position, a rotation locking part 530 for positioning the photoreceptor 27 of the image forming unit 21 in the rotary direction around the axial center, and a ratransfer roller 43 for transferring the color image formed on the intermediate transfer belt 4 to the recording paper sheet 42 at the retransfer position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color printer,
The present invention relates to an image forming apparatus applicable to a color copying machine, a color facsimile, and the like, and an image forming unit used for the same.

[0002]

2. Description of the Related Art A conventional image forming apparatus is disclosed in
The one disclosed in JP-A-36246 or the like is known.

Hereinafter, a conventional image forming apparatus will be described with reference to FIG.
5 will be described. As shown in FIG. 15, the intermediate transfer belt unit 101 includes an intermediate transfer belt 102, a first transfer roller 103, a second transfer roller 104, a cleaner roller 105, a waste toner reservoir 106, and the like. Can be used to superimpose color images. An image forming unit group 108 is provided at the center of the image forming apparatus main body. The image forming unit group 108 includes
Four sets of image forming units 107Bk, 1 each having the same size for each color of black, yellow, magenta, and cyan and having a substantially fan-shaped cross section
07Y, 107M and 107C, and these image forming units 107Bk, 107Y, 107M and 107
C is arranged in an annular shape. Image forming unit 107B
k, 107Y, 107M, and 107C are properly mounted in the image forming apparatus, and the image forming unit and a mechanical drive system and an electric circuit system of other parts of the image forming apparatus are coupled via a mutual coupling member. Thereby, both are mechanically and electrically integrated. Here, the image forming units 107Bk, 107Y, 107M,
107C is supported by a support, and can be rotated around a fixed and non-rotating cylindrical shaft 109 by being driven by a moving motor as a whole. At the time of image formation, the image forming units 107Bk, 1
07Y, 107M, and 107C can be sequentially positioned at an image forming position 110 facing the first transfer roller 103 that supports the intermediate transfer belt 102 by rotational movement.
The image forming position 110 is also an exposure position by the laser signal light 111.

In the image forming apparatus, a laser exposure device 112 is provided below the image forming unit group 108 in a horizontal state. The laser signal light 111 is transmitted to the optical path window 11 formed between the image forming units 107M and 107C.
3 and the shaft 119 through a window opened in a part of the shaft 119
Incident on a mirror 114 fixed therein. Mirror 114
Is reflected and enters the image forming unit 107Bk from the exposure window 115 of the image forming unit 107Bk located at the image forming position 110. In this case, the laser signal light 111 is transmitted to the image forming unit 107.
The light passes through an optical path between a developing unit 116 and a cleaner 117 disposed vertically in Bk and enters an exposed portion on the left side of the photoconductor 118, and the photoconductor 118 is scanned and exposed in the generatrix direction. The toner image formed on the photoconductor 118 is transferred to the intermediate transfer belt 102, and then the image forming unit group 10
8 is rotated 90 degrees, and the yellow image forming unit 1 is rotated.
07Y is located at the image forming position 110. Again, in this case,
The same operation as in the previous black step is performed, and the yellow toner image is superimposed on the black toner image on the intermediate transfer belt 102. A similar operation is further performed using magenta and cyan image forming units 107M and 107C,
A full-color image is completed on the intermediate transfer belt 102. After the full color image is completed on the intermediate transfer belt 102, the recording paper is conveyed by the second transfer roller 104 and the third transfer roller 119, and the color image is simultaneously transferred onto the recording paper. The recording paper to which the color image has been transferred is conveyed to the fixing device 120, whereby the color image is fixed on the recording paper.

[0005]

The above is described in JP-A-7-36.
Although the contents of the image forming apparatus disclosed in Japanese Patent Application Publication No. 246/246 and the like are not disclosed in these conventional examples, a specific configuration for accurately and stably holding each image forming unit at an image forming position is not disclosed. The emergence of such technical means has been desired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem in the prior art. In an image forming apparatus which sequentially switches a plurality of image forming units to output a color image, the image forming unit is connected to the image forming apparatus main body. It is an object of the present invention to provide an image forming apparatus capable of accurately and stably holding the image forming apparatus at a regular position and capable of outputting a high-quality image, and an image forming unit used therefor.

[0007]

In order to achieve the above object, an image forming apparatus according to the present invention comprises: a plurality of image forming units having a rotating body; An image forming unit transferring unit that sequentially rotates and switches between the positions, and engages with at least one axial end of the rotating body from the axial direction of the rotating body located at the image forming position; A rotator supporting member that rotatably supports the image forming unit while positioning the rotator at a proper position of the apparatus main body, and a rotation that positions the image forming unit in a rotational direction around the axis of the rotator. And a locking portion.

[0008] Examples of the rotating member include a photosensitive member and a developing roller.

According to the configuration of the image forming apparatus, the image forming unit can be accurately and stably held at a proper position of the apparatus main body with a simple configuration, even though a plurality of different image forming units are used. As a result, an image forming apparatus capable of outputting a high-quality color image can be realized.

The image forming apparatus according to the present invention may further comprise a rotating body driving means for driving the rotating body, and a rotation locking portion may be provided on the rotating body driving means in the axial direction of the rotating body. Is preferred. According to this preferred example, since a portion to which a load is applied can be gathered in the vicinity, positioning can be stabilized by increasing accuracy and rigidity of the portion. As a result, an image forming apparatus capable of outputting a higher quality color image can be realized. Further, in this case, the one support position of the rotating body axis, the driving force transmitting position by the driving means, and the rotation locking position by the rotation locking portion are substantially coplanar with the rotating body axis. It is preferably above. According to this preferred example, the rotational moment about the support position of one axis is offset, and the influence of the driving force by the driving means hardly affects the support position of the other axis. The forming unit can be accurately and stably held at a proper position of the apparatus main body. As a result, an image forming apparatus capable of outputting a high-quality color image can be realized.

In the image forming apparatus according to the present invention, the rotating member is a photosensitive member, and the image forming unit further includes a developing device driven by developing device driving means. It is preferably provided on the developing device driving means side in the axial direction of the body. According to this preferred example, a portion to which more load is applied can be collected in the vicinity, so that positioning can be stabilized by increasing accuracy and rigidity of the portion. As a result, an image forming apparatus capable of outputting a high-quality color image can be realized. Further, in this case, the one support position of the rotating body axis, the driving force transmitting position by the driving means, and the rotation locking position by the rotation locking portion are substantially coplanar with the rotating body axis. It is preferably above.

In the image forming apparatus according to the present invention, the rotation locking portion controls the rotation of the image forming unit on a plane substantially parallel to a line connecting the rotation axis and the rotation locking position. It is preferable to lock. According to this preferred example, no extra reaction force is applied to the support portion of the rotating body axis, and the rotating body can be held more stably.

Further, in the configuration of the image forming apparatus of the present invention, the rotating member is a photosensitive member, and further includes a developing device, and a developing device driving means for driving the developing device, wherein the rotation locking portion is provided. It is preferable that the rotation of the image forming unit is locked on a plane substantially perpendicular to the direction of the driving force by the developing device driving unit. According to this preferred example, no extra reaction force is applied to the support portion of the rotating body axis, and the rotating body can be held more stably. In this case, it is preferable that the rotation locking portion locks the rotation of the image forming unit near the line of action of the driving force by the developing device driving means. According to this preferred example, almost no reaction force is applied to the support portion of the rotating body axis, and the rotating body can be held more stably.

In the image forming apparatus according to the present invention, it is preferable that the rotation locking portion is provided on the image forming unit transfer means. According to this preferred example, since the rotation locking portion can be provided at a position close to the image forming unit, the rotation of the image forming unit can be stably engaged without providing a large projection or the like on the image forming unit or the apparatus main body. Can be stopped.

Further, in the configuration of the image forming apparatus of the present invention, the rotating member is a photosensitive member, and a developing device; a developing device driving unit for driving the developing device; and a photosensitive member for driving the photosensitive member. Further comprising a driving unit, at the time of image formation, after starting driving the photoconductor by the photoconductor driving unit,
It is preferable to start driving the developing device by the developing device driving means. According to this preferred example, even when the axis of the rotating body is not sufficiently supported, the image forming unit can be accurately and stably held at the proper position of the apparatus main body with a simple configuration. As a result, an image forming apparatus capable of outputting a high-quality color image can be realized.

The image forming apparatus according to the present invention may further include a thrust locking portion provided near the axis of the rotating body for positioning the image forming unit in the axial direction of the rotating body. Is preferred. According to this preferred example, since the rotational moment about the support position of the rotating body axis becomes small, even when the image forming unit is inclined,
The shaft center can be smoothly supported. In this case, it is preferable that the rotation locking portion and the thrust locking portion are provided on the same side in the axial direction of the rotating body. According to this preferred example, since members related to positioning can be gathered in the vicinity, positioning accuracy can be improved.

Further, in the configuration of the image forming apparatus of the present invention, the rotating body is a photosensitive member, a developing device, a developing device driving means for driving the developing device, and a photosensitive member for driving the photosensitive member. And a direction of a rotational moment about the axis of the photoreceptor due to its own weight acting on the image forming unit, and a rotational moment about the axis of the sightseeing object by the developing device driving means. And the magnitude of the rotational moment due to the own weight of the image forming unit is smaller than the magnitude of the rotational moment due to the drive gear of the developing device. According to this preferred example, the rotation locking force of the image forming unit applied to the rotation locking portion is reduced, and the influence of gravity can be reduced, so that stable positioning can be performed.

The image forming unit according to the present invention comprises a rotating body, which is detachably held in the apparatus main body, and rotates the rotating body from an axial direction of the rotating body located at the image forming position. The rotating body supporting member of the apparatus main body is engaged with at least one axial end of the body, the rotating body is positioned at a proper position of the apparatus main body, and the rotation locking section of the apparatus main body is The positioning of the rotating body in the rotation direction about the axis is thereby performed. According to the configuration of the image forming unit, it is possible to realize an image forming unit that can be accurately and stably held at a proper position of the apparatus main body.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to embodiments.

<First Embodiment> First, the first embodiment of the present invention will be described.
The configuration of the image forming apparatus according to the first embodiment will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a printer main body of the image forming apparatus, and a right end face is a front face of the apparatus. 1A is a printer front plate. The printer front plate 1A is hinged to a lower side of the printer outer housing 1D by a hinge shaft 1B.
Can be opened by flipping to the front. FIG. 2 shows a state in which the printer front plate 1A is folded down and opened. Maintenance inside the printer, such as when a paper jam occurs, is performed by opening the printer front plate 1A and opening the inside of the printer significantly.

FIG. 3 shows the intermediate transfer belt unit.
As shown in FIG. 3, the intermediate transfer belt unit 2 includes a unit case 3, an intermediate transfer belt 4, a transfer guide roller 9 for suspending the intermediate transfer belt 4, a re-transfer backup roller 6, a drive roller 8, a tension roller 5, , A waste toner reservoir 10 for containing waste toner, a waste toner full detector 11, a position detector 12, and a cleaner unit 15. The driving roller 8 obtains a driving force by a driving unit (not shown) of the printer main body 1 and drives the intermediate transfer belt 4 in the direction of arrow Y. The cleaner unit 15 includes a cleaning blade 7, a toner receiver 17, and a cam follower 16, and is swingably mounted around a swing shaft 18. Also, the cleaner unit 15
The cleaning blade 7 is urged by means such as a spring (not shown) so that the cleaning blade 7 contacts the drive roller 8 via the intermediate transfer belt 4. The printer main body 1 is provided with a separation / contact cam 52 (see FIGS. 1 and 2), and the separation / contact cam 52 engages with the cam follower 16 when the intermediate transfer belt unit 2 is mounted on the printer main body 1. .
The cleaner unit 15 and the waste toner reservoir 10 are communicated through a communication port 19, and the waste toner scraped off by the cleaning blade 7 by a known means such as a screw shaft is disposed on the inner peripheral side of the intermediate transfer belt 4. The waste toner is conveyed to the waste toner reservoir 10.

The intermediate transfer belt 4 has a thickness of 100 to 50.
It is a film in which a semiconductive (medium resistance) urethane in the form of an endless belt is coated with a fluororesin such as PFA or PTFE.

In order to perform full-color printing on A4 size or letter size recording paper, the circumferential length of the intermediate transfer belt 4 is set to the length in the longitudinal direction (297 mm) of A4 size recording paper, which is the maximum image receiving paper. Body (diameter 30
mm) is set to 377 mm, which is a length (80 mm) that is slightly longer than half of the circumference. At this time, the circumference of the intermediate transfer belt 4 from the retransfer position of the retransfer backup roller 6 to the contact portion of the drive roller 8 with the cleaning blade 7 is set to be 75 mm shorter than the distance of 80 mm. ing.

The moving speed of the intermediate transfer belt 4 is 1.5% lower than the image forming speed of the image forming unit (100 mm / s, which is equal to the peripheral speed of the photosensitive member) in order to prevent the transfer of the toner image into the intermediate transfer belt. It is set to be faster.

When transferring the toner image on the photosensitive member, a voltage of about +2.5 kV (100 μA) is applied to the transfer guide roller 9 and the tension roller 5 by a high voltage power supply (not shown). At this time, if the transfer guide roller 9 is brought into contact with the photosensitive member to transfer the toner image to the intermediate transfer belt 4, a so-called "forward jump" phenomenon occurs before the intermediate transfer belt 4 comes into contact with the photosensitive member. May be disturbed, or it may be difficult to uniformly adjust the contact pressure between the transfer guide roller 9 and the photoconductor. However, such a problem does not occur in the configuration in which the intermediate transfer belt 4 stretched between the transfer guide roller 9 and the tension roller 5 is brought into contact with the photoconductor as in the present embodiment.

The diameter of the driving roller 8 and the retransfer backup roller 6 is 30 mm. The diameter of the tension roller 5 and the transfer guide roller 9 is 15 mm. The peripheral length of the intermediate transfer belt 4 is set to be an integral multiple of the outer peripheral length of each roller, thereby preventing color shift of each color. Reference numeral 20 shown in FIG. 4 is a detection hole for detecting the position of the intermediate transfer belt 4. The position detector 12 is
The tip position of the toner image is determined by optically detecting the passage of the detection hole 20. Thus, the color image can be aligned on the intermediate transfer belt 4.

Here, an optical type position detecting means is used as the position detecting means. However, the present invention is not limited to this. A mechanical type, electric type, magnetic type, etc. position detecting means other than the optical type may be used. You may.

In the center of the left side of the printer body 1, a carriage 22 and a moving motor 23 which constitute an image forming unit transferring means are arranged. The carriage 22 has four image forming units 21Y, 21M, 21C, and 21 each having a substantially fan-shaped cross section for each color of yellow, magenta, cyan, and black.
Bk is arranged and housed in an annular shape. The image forming unit 21 is detachably mounted on a predetermined position of the carriage 22. When the image forming unit 21 needs to be replaced, as shown in FIG. The image forming unit 21 can be replaced by placing the image forming unit 21 below the printer top plate 1C, opening the printer top plate 1C and opening the insertion opening of the image forming unit 21. As described later, the image forming unit 2
Reference numeral 1 denotes a mechanical drive system for properly mounting the image forming unit 21 and other parts of the printer main body 1 in the printer main body 1.
The two are mechanically and electrically integrated by coupling the electric circuit system via the mutual coupling member. The carriage 22 is driven by a moving motor 23 and can rotate around a fixed and non-rotating cylindrical shaft 24 while holding each image forming unit. During image formation, each image forming unit is sequentially positioned at an image forming position 25 facing a transfer position between the transfer guide roller 9 supporting the intermediate transfer belt 4 and the tension roller 5 by rotational movement. The image forming position 25 is also an exposure position by the pixel laser signal light 26, and the image forming unit 21 performs an image forming operation only at this position, and no image forming unit 21 operates at other positions (retraction positions).

FIG. 10 shows an image forming unit. Each image forming unit is different only in the developer to be put in, and the other components are made of the same constituent members. Therefore, the image forming unit 21Bk for black will be described to simplify the description.
Description of other colors is omitted. Note that, for each color, the same portions are denoted by the same reference numerals, and when it is necessary to distinguish the configuration of each color, characters indicating the respective colors are denoted by the reference numerals.
In FIG. 10, 26 is a pixel laser signal light also shown in FIG. 1, 27 is an organic photoreceptor mainly composed of a polycarbonate binder resin using phthalocyanine as a photosensitive material,
28 is a corona charger for negatively charging the photoconductor 27,
Reference numeral 29 denotes a grid for controlling the charging potential of the photoreceptor 27 to be constant, and reference numeral 30 denotes a pixel laser signal light 26 from the image forming unit 21.
An exposure window 31Bk opened to enter the inside is a black developing device. The developing device 31 includes a toner hopper 32
, A developing roller 33, a magnet 34, a doctor blade 35, and the like. The toner hopper 32 contains a negatively charged black toner 36Bk in which a black pigment is dispersed in a polyester resin.
The black toner 36Bk is mixed with a ferrite carrier having a particle diameter of 50 μm, the surface of which is coated with a silicone resin.
3 and develops the photoreceptor 27. Reference numeral 38 denotes a cleaner for cleaning the toner remaining on the surface of the photoreceptor 27 after the transfer. The cleaner 38 includes a cleaning blade 39 made of rubber and a waste toner reservoir 40 for storing the waste toner. . The diameter of the photoconductor 27 is 3
0 mm, and rotates in the direction of the arrow at a peripheral speed of 100 mm / s. The diameter of the developing roller 33 is 16 mm, and the peripheral speed is 1 mm.
Rotate at 40 mm / s. The fan-shaped spread angle of the image forming unit 21 is 90 degrees, which is about 30 degrees for the cleaner 38 and about 60 degrees for the developing unit 31.

Next, returning to FIG. FIG.
Reference numeral 41 denotes a static elimination needle for preventing the toner image from being disturbed when the recording sheet 42 is separated from the intermediate transfer belt 4 (FIG. 3). Reference numeral 43 denotes a retransfer roller as a retransfer unit, which is configured to abut on the retransfer backup roller 6 (FIG. 3) via the intermediate transfer belt 4. The re-transfer roller 43 is 1.5 times higher than the intermediate transfer belt 4 in order to prevent a hollow phenomenon when transferring a toner image.
It is configured to rotate by%.

Reference numeral 53 denotes a paper feed unit for storing the recording paper 42, and the paper feed unit 53 is mounted on a lower portion of the printer main body 1. Reference numeral 54 denotes a paper guide as a paper transport path for transporting the recording paper 42 from the paper feed unit 53 to the retransfer roller 43. 50 is a feeding roller.

Reference numeral 44 denotes a laser exposure device. The laser exposure device 44 includes a semiconductor laser (not shown), a polygon mirror 45, a lens system 46, an intermediate mirror 47, a laser light emission window 55, and the like. Laser exposure device 44
Are the carriage 22, the intermediate transfer belt unit 2, the paper supply unit 53, and the paper guide 54 in the printer outer housing 1D.
It is arranged in the space surrounded by. Reference numeral 49 denotes a center mirror whose reflection surface is located at 3
It is fixed in a downward facing position. Laser exposure device 44
The pixel laser signal light 26 corresponding to the time-series electric pixel signal of the image information from the camera enters the intermediate mirror 47. The pixel laser signal light 26 reflected by the intermediate mirror 47 is transmitted to the optical path window 48 formed between the cleaner 38Y of the yellow image forming unit 21Y and the developing device 31M of the magenta image forming unit 21M, and to the shaft 24. The light enters the center mirror 49 at an elevation angle of 18 degrees through a window opened in the section, is reflected and enters the image forming unit 21Y from the exposure window 30 of the image forming unit 21Y located at the image forming position 25. The pixel laser signal light 26 is transmitted to the image forming unit 2.
The light passes through a passage between the developing device 31Y and the cleaner 38Y disposed in the upper and lower portions of the photoreceptor 27Y and enters the exposed portion on the left side of the photoreceptor 27Y at an elevation angle of 12 degrees, thereby scanning and exposing the photoreceptor 27Y in the generatrix direction. .

Here, as the optical path from the optical path window 48 to the center mirror 49, the image forming units 21Y, 21
Since the gap of the wall between M is used, the carriage 2
2 has little wasted space. Further, since the center mirror 49 is provided at the center of the carriage 22, it can be constituted by a fixed single mirror, and has a simple and easy-to-position arrangement. Further, since the laser exposure device 44 is disposed in a space surrounded by the carriage 22, the intermediate transfer belt unit 2, the paper supply unit 53, and the paper guide 54, the rotation surface of the polygon mirror 45 is inclined with respect to the horizontal plane. Thus, it is possible to effectively utilize the space in the apparatus and to make it easy to reduce the size.

It is desirable that the incident angle of the pixel laser signal light 26 to the intermediate mirror 47 and the center mirror 49 be 30 degrees or less. When the angle is 30 degrees or more, the aberration of the laser beam on the reflection surface becomes large, and the image quality may be deteriorated.
Further, since the image forming position 25 and the laser exposure device 44 must be arranged separately, it is difficult to reduce the size.

The directions of the reflecting surfaces of the intermediate mirror 47 and the center mirror 49 are not limited. However, in order to minimize the contamination by the toner, it is desirable that the reflecting surface be directed below the horizontal plane.

The pixel laser signal light 26 passes through the center mirror 49 through the gap in the wall between the image forming units 21Y and 21M.
Incident on That is, the optical path of the pixel laser signal light 26 reflected on the center mirror 49 and incident on the photoreceptor 27Y (the path between the developing unit 31Y and the cleaner 38Y) is opposite to the developing unit 31Y of the image forming unit 21Y. , The pixel laser signal light 26 is incident on the center mirror 49. This is because, for example, in order to make the capacity of the frequently used black image forming unit 21Bk larger than that of other colors, the black image forming unit 21Bk is used.
The fan-shaped spread angle of k is 120 degrees, and the image forming units 21Y, 21M, and 21C for yellow, magenta, and cyan.
Even if the fan-shaped spread angle of each is 80 degrees,
The breakdown is 90 degrees with the developing unit 31Bk, the cleaner 38Bk
At 30 degrees, and 50 at developing units 31Y, 31M and 31C.
If the angle is 30 degrees with the cleaners 38Y, 38M, and 38C, the toner hopper 32 of the black image forming unit 21Bk can be used without changing the arrangement of the other components described above.
The capacity of Bk can be increased.

Reference numeral 51 denotes a fixing device. The fixing device 51 is provided at an upper portion in the printer main body 1.

Next, a positioning mechanism and a driving mechanism at an image forming position for accurately performing color matching of each color will be described.
This will be described with reference to FIGS.

FIG. 5 is an exploded perspective view showing a positioning mechanism and a drive mechanism of the carriage and the photosensitive member of the image forming unit, FIG. 6 is a sectional view of the carriage cut along a plane passing through the image forming position, and FIG. 7 is an image forming unit. 8 is a side view of the carriage viewed from the right side, FIG. 8 is a perspective view showing a photosensitive body driving mechanism which is a photosensitive body driving unit for driving the photosensitive body located at the image forming position, and FIG. 9 is opposite to the photosensitive body driving mechanism. It is a side view which shows the positioning mechanism of the shaft of the side end surface.

As shown in FIGS. 5 and 6, the carriage 22
Center shaft 24 has a right side wall 520R and a left side wall 520L.
And have been fixed. Right side wall 520R and left side wall 520L
And partition plates 523 are provided at four locations so as to divide the inside of the carriage 22 into four parts.
The image forming units 21 of each color are arranged in each space in the carriage 22 partitioned by the above. Carriage 22
Two partitions 523 are provided at each location where the inside of the device is divided into four parts, and an optical path through which the pixel laser signal light 26 passes is formed between these two partitions 523. Exposure windows 522 are provided on the shaft 24 at a total of eight positions: a position corresponding to the optical path and a position where the pixel laser signal light 26 reflected by the center mirror 49 exits.

A coupling plate 542 fixed to the photoreceptor 27 of the image forming unit 21 is provided on the right side wall 520R.
Is provided with a right notch 526 at the portion where
In the normal position, the coupling plate 542 and the right side wall 520R are provided.
A gap is provided between the coupling plate 542 and the right side wall 520R so as not to come into contact with. Left side wall 520
A collar 54 provided on the left end of the photoreceptor shaft
3 is provided, and the left notch 529 also has a notch dimension larger than the outer diameter of the collar 543 so that the left notch 529 does not contact the collar 543 at a regular position.

525 is a right side wall 520R and a left side wall 520.
L is a guide groove formed inside L.
Reference numeral 25 denotes an image forming unit 2 that guides guide pins 545R and 545L provided on both side walls of the image forming unit 21.
1 is roughly positioned in the carriage 22.

Reference numeral 530 denotes a rotation locking portion. The rotation locking portion 530 is formed on the right side wall 520R of the carriage 22 on the photosensitive member driving mechanism side in the axial direction of the photosensitive member 27 so as to be continuous with the right notch 526. I have. The rotation locking portion 530 engages with a rotation locking pin 531 provided on the right side wall of the image forming unit 21 to perform rotation positioning of the image forming unit 21 around the axis of the photoconductor 27 during image formation.

The rotation locking portion 530 has a surface substantially parallel to a line connecting the axis of the photosensitive member 27 supported at a normal position at the image forming position 25 and the center of the rotation locking pin 531.
The rotation locking pin 531 is locked on that surface.

Further, in order for the image forming unit 21 to be in the image forming operation at the image forming position 25, as shown in FIG. 7, the image forming unit 21 and the carriage 22 are connected to the coupling plate 542 and the right notch 526. Between, collar 543
And the left notch 529, the guide pins 545R, 545
The gap is formed between the L and the guide groove 525 and between the outer surface of the image forming unit 21 and each part of the carriage 22. That is, the image forming unit 21 and the carriage 22 are held in a state where they do not contact each other except for the rotation locking portion 530 and the rotation locking pin 531.

Although not shown in the drawings, in order to prevent the image forming unit 21 from dropping in the centrifugal direction, projections are provided on the outer peripheral surfaces of the side walls 520R and 520L so that they can be inserted and removed. .

Reference numeral 528 denotes a carriage gear fixed to the left side wall 520L, and the carriage gear 528 is connected to a carriage driving mechanism 86 which constitutes a unit transfer means provided on the main body side. The carriage drive mechanism 86 includes a worm gear 89 connected to a drive source, a worm wheel 88, and a gear 87 integrated with the worm wheel 88 and meshing with the carriage gear 528.

The carriage 22 is provided on the left and right main body walls 1.
L and 1R are rotatably supported in parallel with the laser exposure device 44 and the center mirror 49 via bearings 546. The center mirror 49 is a support member (not shown).
Are fixed to the left and right main body walls 1L, 1R.

As shown in FIG. 6, the photosensitive member 27 of the image forming unit 21 has flanges 541 fixed to both ends thereof, and the photosensitive member shaft 540 is integrally fixed to the flange 541. The photoreceptor shaft 540 is rotatably supported on the side wall of the image forming unit 21. A concave tapered surface 548 is formed at the right end of the photoconductor shaft 540. Further, eight pawls 5 are provided around the tapered surface 548 on the photoreceptor shaft 540.
A coupling plate 542 having 47 (FIG. 5) is fixed. With the above configuration, when the coupling plate 542 is rotated, the photosensitive member shaft 540 is rotated, and simultaneously, the flange 541 and the photosensitive member 27 are also rotated. A collar 543 serving as a radial bearing is rotatably attached to the left end of the photoreceptor shaft 540.

As shown in FIG. 5 to FIG.
The photoreceptor 27 is attached to the image forming position 25 on both side walls 1R and 1L.
For accurate positioning, a photoconductor driving mechanism 60 and a detent mechanism 80, which are photoconductor driving means, are provided.

The photoconductor drive mechanism 60 is provided on the right main body wall 1R, and includes an output shaft 70 as a photoconductor support member, a coupling plate 61 which rotates integrally with the output shaft 70, and an output shaft drive gear 71. And a drive mechanism for driving these. The output shaft 70 is movably and rotatably supported in the thrust direction by bearings 77 fixed respectively between the right main body wall 1R and the substrate 67 fixed thereto.

At one end of the output shaft 70, a tip taper portion 75 having a convex tapered surface following the tapered surface 548 of the photoreceptor shaft 540 is formed, and the other end of the output shaft 70 is connected to a thrust bearing 69. It is formed in a spherical shape so as to contact with a small area. The output shaft drive gear 71 is a helical gear having a left-hand helix in the same direction as the rotation direction, and the output shaft drive gear 71
It is fixed to.

Reference numeral 74 denotes a compression spring inserted between the bearing 77 and the output shaft driving gear 71.
Is for constantly biasing the output shaft 70 and the coupling plate 61 to a position (the position shown in FIG. 8) separated from the coupling plate 542 on the photoconductor 27 side. Output shaft 7
Reference numeral 0 denotes a driving unit for moving the thrust bearing 69, which opposes the spring force between the separated position shown in FIG. 8 and the engagement position where the tapered surface 548 and the tapered end portion 75 shown in FIG. The driving gear 72 has a wide tooth width so that the output shaft driving gear 71 is meshed with the driving gear 72 at any position. When the output shaft 70 moves in the thrust direction, the output shaft driving gear 7
1 and the driving gear 72 move while sliding on each other's tooth surfaces.

The coupling plate 61 is for engaging with the coupling plate 542 on the photosensitive member 27 side to transmit power, and has eight coupling claws 65 at the tip similarly to the coupling plate 542. I have. Although the rotation of the coupling plate 61 with respect to the output shaft 70 is prevented by the pin 64, the coupling plate 61 is configured to be able to move by a predetermined amount in the thrust direction. This is to allow the tip of the coupling claw 65 and the tip of the claw 547 of the coupling plate 542 to temporarily escape when colliding with each other. Therefore, the engagement operation between the tapered end surfaces is not hindered. The coupling plate 61 is always urged by the spring 62 to the position of the distal end stopper 63.

Next, the detent mechanism 80 provided on the left main body wall 1L will be described.

The detent mechanism 80 includes a guide plate 81,
It comprises a detent lever 82, a solenoid 85 for moving the detent lever 82, and the like. The guide plate 81 guides a collar 543 provided on the left end of the photoconductor shaft 540 near the image forming position 25, and
For positioning the collar 543 at a regular centrifugal position from the center position of the left side, and is fixed to the left main body wall 1L. The detent lever 82 is rotatably attached to the left main body wall 1 </ b> L by a support shaft 83.
The collar 543 is pressed against the guide plate 81 by the groove to accurately position the collar 543 at the image forming position 25.

The detent lever 82 has a solenoid 85
Through a lever 84. With this configuration, the detent lever 82 is swung by the suction force of the solenoid 85, and the collar 543 is guided by the V-groove of the detent lever 82 to the guide plate 81.
Can be pressed strongly.

The position of the output shaft 70 of the photosensitive member driving mechanism 60 and the position of the V-groove of the detent mechanism 80 are determined by the laser exposure device 44.
And the center mirror 49 are set so as to maintain an accurate parallelism. For this reason, the play of the bearing is minimized, and the photoconductor 27 is always accurately positioned at the predetermined image forming position 25 when the photoconductor drive mechanism 60 and the detent mechanism 80 operate.

Hereinafter, the operation of the image forming apparatus configured as described above will be described.

First, the full-color image forming step will be described. The image forming apparatus in FIG. 1 is in an image forming state. First, yellow image formation is performed. The operation of the image forming unit 21Y will be described with reference to FIG. At the time of image formation, a voltage of -450 V is applied to the grid 29 of the charger 28, whereby the photoconductor 27 is charged to -450V.
The photoconductor 27 is irradiated with the pixel laser signal light 26 to form an electrostatic latent image. After passing through the lens system 46, the pixel laser signal light 26 is reflected twice in a Z-shape (in FIG. 1, facing backward) by the intermediate mirror 47 and the center mirror 49 and reaches the photoconductor 27. At this time, the exposure potential of the photoconductor 27 becomes -50V. The photoconductor 27 is developed by a developing roller 33 carrying a two-component yellow developer 37Y. When the photosensitive member 27 passes through the uncharged area, a DC voltage of −250 V is applied to the developing roller 33 by a high-voltage power supply. As a result, a negative / positive inverted yellow toner image is formed only on the image portion on the photoreceptor 27. At this time, the carriage 22 is at the position shown in FIG. 1, and the yellow image forming unit 21Y is moved to the image forming position 2
5 and the photoconductor 27 is in contact with the intermediate transfer belt 4. By the image forming process of the image forming unit described above, the image is formed by the yellow toner. At this time, the moving speed of the intermediate transfer belt 4 is set to be 1.5% faster than the speed of the photoconductor 27 in order to prevent the hollow transfer of the toner image. As a result, the yellow toner image is transferred onto the intermediate transfer belt 4 simultaneously with the image formation. At this time, a DC voltage of +1.0 kV is applied to the transfer guide roller 9 and the tension roller 5.

After all of the yellow toner image has been transferred onto the intermediate transfer belt 4, the entire carriage 22 is driven by the moving motor 23 to move the carriage 22 in the direction of arrow Q in FIG.
It rotates 0 degrees and stops at the position where the image forming unit 21M reaches the image forming position 25.

When the rotation of the carriage 22 is completed and the image forming unit 21M reaches the image forming position 25, the laser exposure device 44 irradiates the image forming unit 21M with a signal light using a magenta signal as before, and the signal light is emitted. The formation and transfer of a magenta toner image are performed. By this time, the intermediate transfer belt 4 has made one rotation, the timing of writing the magenta signal light is controlled based on the signal from the position detector 12, and the previously transferred yellow toner image is replaced with the next magenta toner image. Are superimposed so as to coincide in position. During this time, since the retransfer roller 43 is retracted to a position where it does not contact the intermediate transfer belt 4, the toner image on the intermediate transfer belt 4 is not disturbed.

As shown in FIGS. 1 and 3, the cleaning unit 15 is rotated in the direction of arrow P with the cam follower 16 being pushed by the separating / contacting cam 52 of the printer body 1 and the swing shaft 15 as a fulcrum. Since the cleaning blade 7 and the toner receiver 17 are separated from the intermediate transfer belt 4, the toner image on the intermediate transfer belt 4 is not disturbed. Further, the cleaning blade 7 is in contact with the overhang portion 4A of the intermediate transfer belt 4,
Even when the cleaning blade 7 is separated, the toner receiver 17 is located closer to the intermediate transfer belt 4 than the tip of the cleaning blade 7, so that the waste toner attached to the cleaning blade 7 spills when the cleaning blade is separated from or connected to the cleaning blade 7. Never.

Thereafter, the entire carriage 22 is again driven by the moving motor 23 to rotate exactly 90 degrees in the direction of arrow Q in FIG.
Stop at the position where it reaches 5. Then, the same operation as for yellow and magenta is performed for cyan.

Finally, the entire carriage 22 is driven by the moving motor 23 to move the carriage 22 in the direction of arrow Q in FIG.
The image forming unit 21Bk stops at the position where the image forming unit 21Bk reaches the image forming position 25, and the image is formed by the black toner. The four color toner images are superimposed on the intermediate transfer belt 4 so as to coincide in position, and a full color image is formed. The final black toner image is transferred to the intermediate transfer belt 4
After the transfer, the retransfer roller 43 is pressed against the retransfer backup roller 6, a voltage of +3 kV is applied, and the recording paper 42 guided from the paper feed unit 53 to the paper guide 54 The color toner images are collectively transferred.
The recording paper 42 to which the toner image has been transferred passes through the fixing device 51, is fixed, and is discharged out of the apparatus.

Thereafter, the entire carriage 22 is driven by the moving motor 23 to move the carriage 22 in the direction of arrow Q in FIG.
And the yellow image forming unit 21Y reaches the image forming position 25 again, and a new full-color image forming process is started.

In this way, 2.5 full-color A4 size prints can be obtained in one minute.

Next, the operation of attaching and detaching the intermediate transfer belt unit and the image forming unit will be described.

As shown in FIG. 2, when the printer front plate 1A is folded down and opened, the opening is opened. When the intermediate transfer belt unit 2 is inserted toward the opening, the intermediate transfer belt unit 2 is guided to a predetermined storage position while being guided in the direction of arrow R by a guide member (not shown).

The opening for the paper jam also serves as the insertion opening of the intermediate transfer belt unit 2, so that the insertion opening of the intermediate transfer belt unit 2 having a large projected area from above is separately provided on the upper surface of the printer body 1. No need. The direction of the guide is obliquely forward and downward when viewed from the operator, so that the intermediate transfer belt unit 2 can be easily mounted in a natural posture. Furthermore, the insertion direction is the center mirror 4
9, the intermediate transfer belt 4 is
Therefore, the photosensitive member 27 and the intermediate transfer belt 4 will not be damaged even if the photosensitive member 27 is not evacuated during attachment and detachment. Since the intermediate transfer belt unit 2 has a sectional shape narrowing toward the center mirror 49, it can be easily inserted into the opening. Also,
It is possible to increase the capacity of the waste toner reservoir 10 while reducing the center distance between the transfer guide roller 9 and the tension roller 5 so that the positioning of the intermediate transfer belt 4 with respect to the photoconductor 27 and the contact pressure can be easily set appropriately. it can.

In conjunction with the insertion operation of the intermediate transfer belt unit 2, the separation cam 52 of the printer main body 1 and the cam follower 16 are engaged, and the cleaning blade 7 is separated from the intermediate transfer belt 4. For this reason, in a normal stop or retreat state, the cleaning blade 7 is separated from the intermediate transfer belt 4, so that the deformation of the cleaning blade 7 can be prevented. Then, only when cleaning is necessary, the separation / contact cam 52 rotates, and the cleaning blade 7 contacts the intermediate transfer belt 4.

When the intermediate transfer belt unit 2 is taken out, the engagement between the separation / contact cam 52 and the cam follower 16 is released, and the cleaning blade 7 comes into contact with the intermediate transfer belt 4 to prevent scattering of waste toner. This take-out direction (the direction opposite to the arrow R) and the detaching cam 5 indicated by the arrow V in FIG.
Since the angle between the second transfer belt 2 and the pressing direction is 90 degrees or less, the intermediate transfer belt unit 2 can be removed smoothly without giving unnecessary resistance.

When the image forming unit 21 is to be attached or detached, the printer top plate 1C is opened, and a unit other than the image forming position 25 (here, the black image forming unit 21Bk located above) is attached and detached. I do. For this reason,
Even when the photoconductor 27 is not evacuated during the attachment / detachment, the photoconductor 2
7 and the intermediate transfer belt 4 are not damaged. In the present embodiment, it is configured to be inserted substantially in the direction of gravity. Since the projected area from above is smaller than that of the intermediate transfer belt unit 2, the operation is easy even from the front of the apparatus. This attachment / detachment direction is determined by the intermediate transfer belt unit 2
It is preferable that the angle is 30 degrees or more and 90 degrees or less with respect to the attaching / detaching direction. When the angle is less than 30 degrees, the capacity of the toner hopper 32 of the developing device 31 at the image forming position 25 cannot be sufficiently secured. When the angle is more than 90 degrees, the operator inserts the toner from the back to the front. This is very inconvenient.

Next, the operation of the apparatus by the driving mechanism will be described.

The image forming unit 21 of each color is provided with the carriage 2
When the worm gear 89 is rotated by rotating the moving motor 23 in the state of being mounted on the carriage 2, the carriage 22 rotates in the direction of the arrow, and the yellow image forming unit 21Y is located at the image forming position 25. When the carriage 22 rotates, the output shaft 70 of the photoconductor drive mechanism 60 is urged by the spring 74 to retreat, and the tapered end portion 75 and the coupling plate 61 are separated from the coupling plate 542 on the photoconductor side. . In this case, the solenoid 85 of the detent mechanism 80 is also turned off, and the detent lever 82
Is retracted to the position indicated by the broken line in FIG. In this case, a motor (not shown) for driving the photoconductor driving mechanism 60 is stopped. When the yellow photoconductor 27Y moves while rubbing the surface of the intermediate transfer belt 4 and comes near the image forming position 25, the moving motor 23 stops, the worm gear 89 stops, and the carriage 22 is locked at that position. .

When the carriage 22 stops, the solenoid 85 of the detent mechanism 80 is immediately turned on, and the detent lever 82 is urged in the direction of pressing the collar 543 of the photoreceptor shaft 540 against the guide plate 81. Position the collar 543 at the specified position.

At the same time, the thrust bearing 69 is
Is pushed to the left in FIG. 6 against the spring force. When the output shaft 70 is pushed to the left in FIG.
0 is the tapered surface 54 of the photoreceptor shaft 540.
8 and advance while moving the photoconductor shaft 540 so as to match the axis of the output shaft 70. Further, when the thrust bearing 69 pushes the output shaft 70 to the left in FIG. 6, the tapered end portion 75 and the tapered surface 548 are engaged, and the axis of the photosensitive member shaft 540 and the axis of the output shaft 70 are completely aligned. It will be in the same state. As a result, the photoconductor 27Y is accurately positioned at the image forming position 25. At this time, the thrust force pressed by the output shaft 70 is applied to the flange 5
The end face of 41 presses the side plate bearing of the image forming unit 21Y, and this portion hits the left side wall 520L of the carriage 22, and is received by the left side wall 520L. When the tip taper portion 75 is engaged with the tapered surface 548, the coupling plate 542 and the coupling plate 61 are also engaged with each other, and a state in which the rotational force can be transmitted is achieved.

By operating the detent mechanism 80 and the photoconductor driving mechanism 60 as described above, the yellow photoconductor 27Y is positioned at an accurate position. At this time, the image forming unit 21Y integrated with the photoconductor 27Y moves in the carriage 22 together with the photoconductor 27Y. Since the image forming unit 21Y is freely held in the carriage 22, the moving operation of the carriage 22 when positioning the image forming unit 21Y is not hindered. The carriage 22 has a spur gear 528 and a gear 8.
Although there is some backlash in the rotating direction due to backlash between the photosensitive member 27 and the photosensitive member 27, the photosensitive body 27Y is positioned by the positioning mechanism on the main body side regardless of the carriage 22.
Accurate positioning is achieved without these effects.

In this state, the image forming unit 21Y is rotatably supported about the axis of the photoreceptor 27Y.

When the positioning of the photoconductor 27Y is completed, the motor for driving the photoconductor starts rotating, and the photoconductor 27Y starts rotating. When these components start to move, each process element starts to operate, and a yellow toner image is sequentially formed on the photoreceptor 27Y.
It is transcribed on top.

During this image forming operation, the output shaft 70 is pressed to the left by the thrust bearing 69. Further, the solenoid 85 is kept ON, and the detent lever 82 keeps holding the collar 543. Furthermore, photoconductor 2
Due to the rotation load of 7Y, the image forming unit 21Y tries to rotate counterclockwise around the photoreceptor shaft 540, but the rotation locking portion 530 and the rotation locking pin 531 are engaged, so that the image forming unit 21Y is rotated. Positioning in the rotation direction is performed. At this time, the image forming unit 21 and the carriage 2
2 is held in a state where they do not contact each other except for the rotation locking pin 531 and the rotation locking portion 530. The rotation locking portion 530 is provided between the axis of the photoreceptor 27Y and the rotation locking pin 531.
The rotation locking pin 531 is locked on a plane parallel to the line connecting the centers of the two, so that no extra reactive force acts on the engaging portion between the tapered end portion 75 and the tapered surface 548.

The rotation locking portion 530 and the rotation locking pin 53
1 is also used for the positioning operation of the image forming unit 21Y.
Desirably, it is configured so as not to contact and not to disturb the positioning operation.

When the intermediate transfer belt 4 makes one rotation (at this time, the photoreceptor 27Y makes four rotations), the yellow image formation ends, the motor stops, and the intermediate transfer belt 4 stops at the initial position.

When the intermediate transfer belt 4 and the photosensitive member 27Y stop, the solenoid 85 is turned off, and the detent lever 82 is released. At the same time, the thrust bearing 69 is retracted rightward, the output shaft 70 is retracted by the force of the spring 74, and the coupling plate 61 and the tapered end portion 75 are separated from the coupling plate 542 and the photosensitive member shaft 540. With the above operation, the positioning of the photoconductor 27Y is released, and the carriage 22 can be rotated.

The output shaft 70 is rotated counterclockwise toward the photoconductor 27Y. However, when the motor stops and the photoconductor 27Y stops, the photoreceptor 27Y has a rotational load. There is a case where the pressing force is kept applied to the side surface of the coupling claw 547 of the coupling on the photoconductor side. In this state, frictional force acts on the side surfaces of the claws, making it difficult to pull out the coupling plate 61 from the coupling plate 542.
In the present embodiment, the output shaft drive gear 71 is formed of a helical gear, and the twist direction thereof is set to the same left-hand twist as the rotation direction, so that the coupling plate 61 is in the opposite direction to the drive direction of the photoconductor 27Y. It is pulled out while rotating by the twist of the tooth surface. As a result, no frictional force is applied to the side surfaces of the claws, so that the coupling plate 61 can be easily pulled out of the coupling plate 542.

In the present embodiment, the coupling operation in the thrust direction between the detent mechanism 80 and the output shaft 70 is performed at the same time. However, a lateral force is applied to the coupling claw 65 and the coupling claw 547 of the coupling on the photosensitive member side. In this case, a frictional force is applied to the claws, making the attaching / detaching operation somewhat difficult. Therefore, it is desirable that the output shaft 70 and the photosensitive member shaft 540 have the same axis as much as possible during the coupling operation. For this purpose, the detent mechanism 80 is used during the wearing operation.
It is more reliable and smoother to move the output shaft 70 before moving the output shaft 70 and to operate the output shaft 70 earlier than the detent mechanism 80 when the output shaft 70 is disengaged after the positioning of the output shaft 70 on the opposite side of the photoreceptor shaft 540 in advance is performed. A simple attachment / detachment operation can be realized. In particular, in the case of a configuration in which the output shaft 70 is separated by the force of the spring 74 during the disengagement operation, the claws are difficult to separate from each other if a load is applied to the coupling portion. It is effective to delay it.

In this embodiment, the output shaft 7
Although zero is returned by the force of the spring 74, it may be forcibly returned by the drive mechanism on the thrust bearing 69 side.

When the coupling between the photoreceptor shaft 540 and the output shaft 70 is released, the worm gear 89 rotates again, and the carriage 22 rotates by 90 degrees in the direction of the arrow in FIG. As a result, the next magenta image forming unit 21
M moves near the image forming position 25 and stops. Then, the photoconductor drive mechanism 60 and the detent mechanism 80 operate again, and the magenta photoconductor 27M is positioned.
Thereafter, a coupling operation between the photoconductor shaft 540 and the output shaft 70 is performed, and a second-color image forming operation is started.

As described above, the switching operation and the image forming operation are sequentially repeated to form four color images on the intermediate transfer belt 4, which are transferred onto the recording paper 42.

In the present embodiment, the operation of rotating the carriage 22 at 90 degrees is performed in about 0.6 seconds, and the operation of attaching and detaching the coupling of the output shaft 70 is performed in about 0.2 seconds.

As described above, according to the present embodiment, the tapered end portion 75 of the output shaft 70 is connected to the tapered surface 54 of the photosensitive member 27.
8, the photoreceptor 27 is positioned at a regular position of the printer main body 1, the image forming unit 21 is rotatably supported, and the rotation locking portion 530 is rotated with the rotation locking pin 531.
And the positioning of the image forming unit 21 in the rotational direction is performed, so that the photosensitive member 27 and the image forming unit 21 can be easily connected to the printer main body 1 with a simple configuration while using a plurality of different photosensitive members 27. It can be accurately and stably held at a regular position. As a result, an image forming apparatus capable of outputting a high-quality color image can be realized.

A rotation locking portion 53 is provided on the photosensitive member driving mechanism side.
By providing 0, a portion to which a load is applied can be gathered in the vicinity, and positioning can be stabilized by increasing the accuracy and rigidity of the portion. As a result, an image forming apparatus capable of outputting a high-quality color image can be realized.

Since the rotation locking portion 530 locks the rotation locking pin 531 on a plane parallel to a line connecting the axis of the photosensitive member 27 and the center of the rotation locking pin 531, the output is provided. No extra reaction force is applied to the shaft 70 and the tip taper 75,
The photoconductor 27 can be held more stably.

Further, the rotation locking portion 530 is
The rotation locking portion 530 can be provided at a position close to the image forming unit 21. As a result, the rotation of the image forming unit 21 can be stably locked without providing a large protrusion or the like on the image forming unit 21 or the apparatus main body.

<Second Embodiment> Next, a second embodiment of the present invention will be described.
The configuration and operation of the image forming apparatus according to the embodiment will be described with reference to FIGS.

FIG. 11 is a sectional view of the carriage cut along a plane passing through the image forming position, and FIG. 12 drives a photosensitive member driving mechanism which is a photosensitive member driving means for driving a photosensitive member located at the image forming position and a developing unit. FIG. 13 is a side view of the image forming unit and the carriage viewed from the right side, showing a developing unit driving mechanism as a developing unit driving unit.

Reference numeral 550 denotes a developing device drive input gear to which power for driving the developing device 31 is input from the apparatus main body. The developing device drive input gear 550 is fixed to an input shaft 551 protruding from the right side surface of the image forming unit 21. Have been. The right cutout 526 (FIG. 5) has a cutout shape such that the right cutout 526 does not contact the coupling plate 542 and the developing device drive input gear 550 at the properly positioned position. Reference numeral 552 denotes a developing device driving gear, which forms a developing device driving unit together with another developing device driving mechanism. Reference numeral 554 denotes a bearing fixed to the right main body wall 1R, which rotatably supports the drive shaft 553. The developing device drive gear 552 is fixed to the drive shaft 553,
The developing device drive input gear 55 of the image forming unit 21 which is driven by a drive source (not shown) and is located at the image forming position 25.
It is configured to mesh with zero.

The rotation locking pin 53 on the developing device driving means side
As shown in FIG. 11, reference numeral 1 denotes a taper surface 548 which is slightly longer than that of the first embodiment, and which is a position for supporting the axis of the photosensitive member 27, and a developing device which is a driving force transmitting position. The meshing position between the drive input gear 550 and the developing device drive gear 552 and the rotation locking position by the rotation locking portion 530 are configured to be located on substantially the same plane perpendicular to the axis of the photoconductor 27. ing.

The arrow F shown in FIG. 13 indicates the developing device driving input gear 550 and the developing device driving gear 55 at the image forming position 25.
2 shows the direction of the driving force of the developing device driving gear 552 when the gears 2 mesh with each other, and 555 shows the action line of the driving force F. The rotation locking portion 530 is substantially perpendicular to the action line 555 and has a rotation locking pin 531 near the action line 555.
Is locked.

Reference numeral 556 denotes a thrust guide which is a thrust locking portion.
It is provided near the axis of the R photoconductor 27.

The photosensitive member shaft 5 which is the axis of the photosensitive member 27
A taper surface 561 similar to the taper surface 548 at the right end is formed at the left end of 40.

Reference numeral 557 denotes a detent mechanism provided on the left main body wall 1L. The detent mechanism 557 includes a detent shaft 558 that is a photosensitive member support member, and a drive mechanism that drives the shaft. The detent axis 558 is
A bearing 560 fixed to each of the left main body wall 1L and the substrate 559 fixed to the left body wall 1L is movably supported in the thrust direction. At one end of the detent shaft 558, a tip taper portion 562 having a convex tapered surface following the tapered surface 561 is formed.
63 is formed in a spherical shape so as to contact with a small area.

Reference numeral 564 denotes a compression spring inserted between the bearing 560 and the retaining ring 565. Things. The detent shaft 558 is driven by a driving means for moving the thrust bearing 563 by using a taper surface 561 and a tip taper portion 562 shown in FIG.
Can be moved to an engagement position at which is engaged and a position separated by the compression spring 564.

Hereinafter, the operation of the image forming apparatus configured as described above will be described. The description of the same parts as in the first embodiment is omitted.

The carriage 22 rotates and the yellow image forming unit 21Y is carried to the image forming position 25. At this time, the output shaft 70 of the photoconductor driving mechanism 60 and the detent shaft 558 of the detent mechanism 557 are connected to the spring 74.
And the spring 564 urges the spring to retract, and the distal end taper portion 75
And the coupling plate 61 are the coupling plate 54 on the photoconductor side.
2 and a detent axis 558
And the tapered surface 56 of the photoreceptor shaft 540
1 is also at a distance. The motor (not shown) for driving the photoconductor driving mechanism 60 is stopped. When the yellow photoconductor 27Y is carried while rubbing the surface of the intermediate transfer belt 4 and comes near the image forming position 25, the moving motor 23 stops, the worm gear 89 stops, and the carriage 22 is locked at that position. You.

When the carriage 22 stops, the thrust bearings 69 and 563 immediately move to the output shaft 70 and the detent shaft 5.
58 is pushed out toward the photoreceptor shaft 540 against the spring force.
When the output shaft 70 and the detent shaft 558 are extruded toward the photoconductor shaft 540 in this manner, the respective tapered portions 75 and 562 of the photoconductor shaft 540 are respectively tapered.
561, the output shaft 70, the detent shaft 558
Moves the photoreceptor shaft 540 to the output shaft 70 and the detent shaft 558.
Move forward while moving to match the axis of. Thereby, the tip taper portions 75 and 562 and the taper surface 54
8, 561 are combined. Thrust bearing 6
When the output shaft 70 and the detent shaft 558 further push the output shaft 70 and the detent shaft 558 toward the photoreceptor shaft 540, the axis of the photoreceptor shaft 540 and the axis of the output shaft 70 and the detent shaft 558 completely coincide with each other. 27Y is accurately positioned at the image forming position 25. At this time, the thrust force pressed by the detent shaft 558 is set to be larger than the thrust force pressed by the output shaft 70, whereby the side plate bearing of the image forming unit 21Y is pressed, and this portion is moved by the carriage. 22 is received by a thrust guide 556 provided on the right side wall 520R.
When the tip taper portion 75 is engaged with the tapered surface 548, the coupling plate 542 and the coupling plate 61 are also engaged with each other, and a state in which the rotational force can be transmitted is achieved.

The magnitude of the pressing force in the thrust direction should be set in consideration of not only the pressing force by the output shaft 70 and the detent shaft 558 but also the pressing force in the thrust direction by the spring-like electric contacts. is there.

By operating the detent mechanism 557 and the photoconductor driving mechanism 60 in this manner, the yellow photoconductor 27Y is positioned at an accurate position. Photoconductor 27Y
When the image forming unit 21Y is positioned in the carriage 22, the position of the image forming unit 21Y in the carriage 22 and the difference in the timing at which the tapered end portions 75, 562 and the tapered surfaces 548, 561 respectively match are determined. Even if it is inclined, since the thrust guide 556 is provided near the photoreceptor shaft 540, the rotational moment about the engaging portion between the tapered end portion 75 and the tapered surface 548 becomes small, and the tapered end portion 75, 562 and the tapered surfaces 548 and 561 respectively fit smoothly.

The thrust guide 556 is connected to the photosensitive member shaft 5.
It is preferably in the form of a ring centered at 40. Also,
Before the tip taper portion 75 and the taper surface 548 are sufficiently fitted, the tip taper portion 75 and the taper surface 548 are so arranged that the thrust guide 556 does not receive the image forming unit 21Y.
It is effective to complete the engagement with the front end taper portion 562 and the engagement with the tapered surface 561 before the engagement.

In this state, the image forming unit 21Y is rotatably supported about the axis of the photosensitive member 27Y.

When the positioning of the photoconductor 27Y is completed, the motor for driving the photoconductor starts to rotate, whereby the photoconductor 27Y starts to rotate. Thereafter, with a slight delay, the motor for driving the developing device starts rotating. When these components start to move, each process element starts to operate, a yellow toner image is sequentially formed on the photoconductor 27Y, and this toner image is sequentially transferred onto the intermediate transfer belt 4.

During this image forming operation, the output shaft 7
0, detent shaft 558 is thrust bearing 69, 563
Pressed by. Further, the image forming unit 21
Y receives a rotational moment about the axis of the photoconductor 27Y by the driving force F of the developing device driving gear 552,
Since the rotation locking portion 530 locks the rotation locking pin 531 at a position near the action line 555 of the driving force F and on a substantially vertical surface, the driving force F is offset by the reaction force of the rotation locking portion 530. , Has little effect on the engagement between the tapered end portion 75 and the tapered surface 548.

Further, the tapered end portion 75 and the tapered surface 548
, The engagement position between the developing device drive input gear 550 and the developing device drive gear 552, and the rotation locking position by the rotation locking portion 530 are substantially the same plane perpendicular to the axis of the photoconductor 27. Since it is on the upper side, the rotational moment about the engagement position between the tip tapered portion 75 and the tapered surface 548 is also canceled, and the engagement between the tip tapered portion 562 and the tapered surface 561 is hardly affected.

Further, only the pressing force of the thrust bearings 69, 563 causes the tapered end portions 75, 562 and the tapered surface 5 to be formed.
48 and 561 do not sufficiently match each other, but when the motor for driving the photosensitive member starts rotating, relative movement occurs in each part, and the tapered end portions 75 and 562 and the tapered surfaces 548 and 561 are moved. Fit well. Also in this case, since the motor for driving the developing device starts rotating slightly later than the motor for driving the photosensitive member, the movement is not hindered.

When the intermediate transfer belt 4 makes one rotation, the yellow image formation is completed, the motor stops, and the intermediate transfer belt 4 stops at the initial position.

When the intermediate transfer belt 4 and the photoreceptor 27Y stop, the thrust bearings 69 and 563 move back and forth, and the output shaft 70 and the detent shaft 558 move back by the force of the springs 74 and 564. The tip taper portion 75 includes the coupling plate 542 and the photosensitive member shaft 540.
And the distal end taper portion 562 is
The carriage 22 is rotatable apart from the carriage 61.

In the present embodiment, the output shaft 7
0, the detent shaft 558 is returned by the force of the springs 74, 564, but the thrust bearings 69, 563
May be forcibly returned by the drive mechanism on the side.

When the coupling and the detent are released, the worm gear 89 rotates again and the carriage 22
Rotates by 90 degrees. Accordingly, the next magenta image forming unit 21M moves to the vicinity of the image forming position 25 and stops. Then, the detent mechanism 80 and the photoconductor driving mechanism operate again, and the magenta photoconductor 27M is positioned. Thereafter, a coupling operation of the photoconductor shaft 540, the output shaft 70, and the detent shaft 558 is performed, and a second color image forming operation is started.

As described above, the switching operation and the image forming operation are repeated, so that a four-color image is formed on the intermediate transfer belt 4 and is transferred onto the recording paper.

As described above, according to the present embodiment, the rotation locking portion 530 is provided on the developing device driving mechanism side,
Since a portion to which more load is applied can be gathered in the vicinity, positioning can be stabilized by increasing accuracy and rigidity of the portion. As a result, an image forming apparatus capable of outputting a high-quality color image can be realized.

Further, the tapered end portion 75 and the tapered surface 548
, The engagement position between the developing device drive input gear 550 and the developing device drive gear 552, and the rotation locking position by the rotation locking portion 530 are located on substantially the same plane perpendicular to the axis of the photoconductor 27. With this arrangement, the rotational moment about the engagement position between the tip taper portion 75 and the tapered surface 548 is canceled out, and the driving force of the developing device drive gear 225 is applied to the engagement portion between the tip taper portion 562 and the tapered surface 561. Is hardly affected, so that the photosensitive member 27 and the image forming unit 21 can be accurately and stably held at the proper positions of the printer main body 1 with a simple configuration. As a result, an image forming apparatus capable of outputting a high-quality color image can be realized.

Further, the rotation locking portion 530 is connected to the action line 555.
By adopting a configuration in which the rotation locking pin 531 is locked on a plane substantially perpendicular to the surface, no extra reaction force is applied to the detent shaft 558 and the tapered end portion 562, and the photoconductor 27 is held more stably. be able to.

In addition, the rotation locking portion 530 is connected to the action line 555.
, The detent shaft 558 and the tapered end portion 56 are provided.
2 is hardly affected by the reaction force, and the photoconductor 27 can be held more stably.

Further, by adopting a structure in which the motor for driving the developing device starts to rotate slightly later than the motor for driving the photosensitive member, the tapered end portions 75 and 562 can be formed only by the pressing force of the thrust bearings 69 and 563. Face 54
8 and 561 do not sufficiently match each other, relative movement occurs at each portion, and the tapered end portions 75 and 562 and the tapered surfaces 548 and 561 sufficiently match. Unit 21 to printer body 1
Can be accurately and stably held at the correct position.
As a result, an image forming apparatus capable of outputting a high-quality color image can be realized.

Further, since the thrust guide 556 is provided near the photoreceptor shaft 540, the rotational moment about the engagement between the tapered portion 75 and the tapered surface 548 is reduced, so that the image forming unit 21Y can be used. Even when inclined in the carriage 22, the tapered end portions 75 and 562 and the tapered surfaces 548 and 561 can be smoothly fitted.

Further, since the rotation locking portion 530 and the thrust guide 556 are provided on the same side in the axial direction of the photosensitive member 27, members related to positioning can be gathered in the vicinity, and positioning accuracy can be improved.

In the present embodiment, either the developing device driving input gear 550 or the developing device driving gear 552 is
It is also possible to adopt a configuration in which a relief is provided so that there is no problem even if the tooth tips come into contact with each other at the time of meshing.

[0129] The substantially co-planar surface is the same as the detent shaft 55.
8 and a state where no extra reactive force is applied to the tip taper portion 562, and there is substantially no problem if the distance is less than 1/20 of the distance between the support positions on both sides of the photoreceptor shaft 540.

Further, the thrust guide 556 may be provided on the image forming unit 21 side, or may be provided directly on the apparatus main body.

<Third Embodiment> FIG. 14 is a side view of a part of an image forming unit and a carriage of an image forming apparatus according to a third embodiment of the present invention as viewed from the right side.

In FIG. 14, reference numeral 566 denotes the position of the center of gravity of the image forming unit 21 when located at the image forming position.
Arrow G indicates the direction of gravity applied to the center of gravity 566.
Photoconductor 27 due to gravity G acting on image forming unit 21
Of the developing device drive gear 552
And the direction of the rotational moment about the axis of the photoreceptor 27 is reversed. Further, the magnitude of the rotational moment due to gravity G is configured to be smaller than the magnitude of the rotational moment due to the developing device drive gear 552. Other configurations and operations are the same as those of the above-described second embodiment, and a description thereof will be omitted.

When the motor for driving the developing device starts to rotate,
The driving force F causes the image forming unit 21 to receive a rotational moment in the direction of arrow H. The rotation moment about the axis of the photoconductor 27 due to the gravity G acts in the direction opposite to the arrow H. At this time, since the magnitude of the rotational moment due to the gravity G is smaller than the magnitude of the rotational moment due to the developing device drive gear 552, the image forming unit 2 is reduced by the difference.
1 receives a rotational moment in the direction of arrow H. That much
The rotation locking force of the image forming unit 21 applied to the rotation locking portion 530 is reduced, and the image forming unit 21 is less likely to be displaced in the rotational direction than when only the driving force F is received, and is stable. Thus, the positioning in the rotation direction is performed. Although the center of gravity 566 changes with time according to the amount of toner in the toner hopper 32 and the amount of waste toner in the waste toner reservoir 40, it is desirable that the above-mentioned relationship be established even between the changes with time. Furthermore, if a vertical line passing through the center of gravity is configured to pass between the axis of the photoconductor 27 and the contact point 590 between the rotation locking portion 530 and the rotation locking pin 531, the gravity G due to the change with time changes. This is desirable because the change in the rotational moment can be reduced.

As described above, according to the present embodiment, the rotational moment about the axis of the photosensitive member 27 due to the gravity G is opposite to the direction of the rotational moment about the axis of the photosensitive member 27 due to the developing device drive gear 552. And the magnitude of the rotational moment due to gravity G is smaller than the magnitude of the rotational moment due to the developing device drive gear 552, so that the rotation of the image forming unit 21 on the rotation locking portion 530 can be controlled. The stopping force is reduced, and the rotation locking portion is not separated by the rotation moment about the axis of the photoconductor 27 due to the gravity G, so that stable positioning can be performed.

In each of the above embodiments, the case where the image forming units 21 of four colors of black, yellow, magenta, and cyan are used has been described as an example, but the type and number of colors are not limited. Further, image forming units having different capacities may be used.

Although the diameter of the photosensitive member 27 is 30 mm and the peripheral speed is 100 mm / s, the diameter and the peripheral speed of the photosensitive member are not limited. Further, the process conditions such as the developing method, the applied voltage, and the peripheral speed of the intermediate transfer belt 4 are not limited to the examples described in the above-described embodiment. For example, a non-magnetic one-component developing process may be used.

The configuration of the intermediate transfer belt unit 2 is not limited to the configuration described in the above embodiment. The number and diameter of the rollers that stretch the intermediate transfer belt 4 are not limited.
Further, although the cleaning blade 7 is used as the belt cleaning means, the belt cleaning means and its position are also arbitrary. Further, the life of the intermediate transfer belt 4 is
When there is no need to replace the intermediate transfer belt 4 such as when the life of the printer main body 1 is about the same, the intermediate transfer belt unit 2 may not be detachable from the printer main body 1.

The retransfer roller 43 is used as retransfer means.
However, other transfer means such as a corona charger may be used.

Further, the photoreceptor shaft 540 need not be a penetrating shaft. For example, they may be provided integrally on the left and right flanges 541, respectively.

Further, the tapered surfaces 548 and 561 need not be provided at the protruding end of the photoconductor shaft 540. For example, left and right flanges 541 or coupling plates 542
May be provided with a tapered surface as a hole.

In each of the above embodiments, the case where the rotating body of the image forming unit 21 to be positioned is the photosensitive body 27 has been described as an example. However, the rotating body is not necessarily limited to the photosensitive body 27. Instead, for example, the developing roller 33 which is a component of the image forming unit 21 may be used.

[0142]

As described above, according to the present invention,
Although a plurality of different image forming units are used, the image forming unit can be accurately and stably held at a proper position of the apparatus main body with a simple configuration. As a result, an image forming apparatus capable of outputting a high-quality color image can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a method of attaching and detaching each unit of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of an intermediate transfer belt unit used in the image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is a perspective view illustrating a configuration of an intermediate transfer belt used in the image forming apparatus according to the first embodiment of the invention.

FIG. 5 is an exploded perspective view showing a carriage and a photosensitive member positioning mechanism and a driving mechanism of the image forming unit of the image forming apparatus according to the first embodiment of the present invention.

FIG. 6 is a sectional view of the carriage cut along a plane passing through an image forming position of the image forming apparatus according to the first embodiment of the present invention.

FIG. 7 is a side view of the image forming unit and the carriage of the image forming apparatus according to the first embodiment of the present invention as viewed from the right side.

FIG. 8 is a perspective view illustrating a photoconductor driving mechanism that is a photoconductor driving unit that drives a photoconductor located at an image forming position of the image forming apparatus according to the first embodiment of the present invention.

FIG. 9 is a side view illustrating a shaft positioning mechanism on an end surface of the image forming apparatus according to the first embodiment that is opposite to the photosensitive member driving mechanism.

FIG. 10 is a cross-sectional view illustrating a configuration of an image forming unit of the image forming apparatus according to the first embodiment of the present invention.

FIG. 11 is a sectional view of a carriage cut along a plane passing through an image forming position of the image forming apparatus according to the second embodiment of the present invention.

FIG. 12 illustrates a photosensitive member driving mechanism that is a photosensitive member driving unit that drives a photosensitive member located at an image forming position of an image forming apparatus according to a second embodiment of the present invention, and a developing device driving unit that drives a developing device. FIG. 4 is a perspective view illustrating a developing device driving mechanism.

FIG. 13 is a side view of a part of an image forming unit and a carriage of an image forming apparatus according to a second embodiment of the present invention as viewed from the right side.

FIG. 14 is a side view of a part of an image forming unit and a carriage of an image forming apparatus according to a third embodiment of the present invention as viewed from the right side.

FIG. 15 is a cross-sectional view illustrating a configuration of a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer main body 1A Printer front plate 1B Hinge axis 1C Printer top plate 1D Printer exterior housing 1R Right main body wall 1L Left main body wall 2 Intermediate transfer belt unit 3 Unit case 3A Surface defining cross section 3B Surface defining cross section 4 Intermediate Transfer belt 4A Overhang portion 5 Tension roller 6 Retransfer backup roller 7 Cleaning blade 8 Drive roller 9 Transfer guide roller 10 Waste toner reservoir 11 Waste toner full detector 12 Position detector 15 Cleaner unit 16 Cam follower 17 Toner receiver 18 Oscillating shaft DESCRIPTION OF SYMBOLS 19 Communication opening 20 Detection hole 21 Image forming unit 22 Carriage 23 Moving motor 24 Axis 25 Image forming position 26 Pixel laser signal light 27 Photoconductor 28 Corona charger 29 Grid 30 Exposure window 31 Developing device 32 Toner hot 33 developing roller 34 magnet 35 doctor blade 36 toner 37 two-component developer 38 cleaner 39 cleaning blade 40 waste toner reservoir 41 static elimination needle 42 recording paper 43 retransfer roller 44 laser exposure device 45 polygon mirror 46 lens system 47 intermediate mirror 48 optical path window 49 Center Mirror 50 Feeding Roller 51 Fixing Device 52 Separation / Contact Cam 53 Paper Feeding Unit 54 Paper Guide 55 Laser Light Emission Window 60 Photoconductor Drive Mechanism 61 Coupling Plate 62 Spring 63 Tip Stopper 64 Pin 65 Coupling Claw 67 Substrate 69 Thrust Bearing 70 Output shaft 71 Output shaft drive gear 72 Drive gear 74 Compression spring 75 Tip taper 77 Bearing 80 Detent mechanism 81 Guide plate 82 Detent lever 83 Support shaft 84 Lever 85 Solenoid 86 Carriage driving mechanism 87 gear 88 worm wheel 89 worm gear 101 intermediate transfer belt unit 102 intermediate transfer belt 103 first transfer roller 104 second transfer roller 105 cleaner roller 106 waste toner reservoir 107 image forming unit 108 image forming unit group 109 axis 110 image forming Position 111 Laser light 112 Laser exposure device 113 Optical path window 114 Mirror 115 Exposure window 116 Developing device 117 Cleaner 118 Photoconductor 119 Third transfer roller 120 Fixing device 520R Right side wall 520L Left side wall 522 Exposure window 523 Partition plate 524 Optical path 525 Guide groove 526 Right cutout 528 Spur gear 529 Left cutout 530 Rotation locking part 531 Rotation locking pin 540 Photoconductor shaft 541 Flange 542 Coupling plate 543 Color 54 Guide pin 546 Bearing 547 Claw 548 Tapered surface 550 Developing device drive input gear 551 Input shaft 552 Developing device drive gear 553 Drive shaft 554 Bearing 555 Line of action of drive force F 556 Thrust guide 557 Detent mechanism 558 Detent shaft 559 Substrate 560 Bearing 561 Taper Surface 562 Tip taper portion 563 Thrust bearing 564 Compression spring 565 Retaining ring 566 Center of gravity

Claims (15)

[Claims] A plurality of image forming units each having a rotating body; an image forming unit transporting unit for sequentially rotating and switching the plurality of image forming units between an image forming position and a retreat position; and the image forming position. At least one axial end of the rotator is engaged from the axial direction of the rotator located at the position of the rotator, and the rotator is positioned at a regular position of the apparatus main body, and the image forming unit is rotatable. An image forming apparatus comprising: a rotating member supporting member for supporting; and a rotation locking portion for positioning the image forming unit in a rotational direction around the axis of the rotating member. 2. The image forming apparatus according to claim 1, wherein the rotating body is a photoconductor or a developing roller. 3. The image forming apparatus according to claim 1, further comprising rotating body driving means for driving the rotating body, wherein a rotation locking portion is provided on the rotating body driving means side in the axial direction of the rotating body. 4. The image forming apparatus according to claim 1, wherein the rotating body is a photoreceptor, and the image forming unit further includes a developing device driven by the developing device driving means. The image forming apparatus according to claim 1 provided. 5. A position where one of the shafts of the rotating body is supported, a position where the driving force is transmitted by the driving means, and a position where the rotation is locked by the rotation locking portion are substantially on the same plane perpendicular to the shaft of the rotating body. The image forming apparatus according to claim 3. 6. The image forming apparatus according to claim 1, wherein the rotation locking portion locks the rotation of the image forming unit on a plane substantially parallel to a line connecting the rotation body axis and the rotation locking position. . 7. The image forming apparatus according to claim 1, wherein the rotating body is a photosensitive member, and further includes a developing device, and a developing device driving means for driving the developing device, wherein the rotation locking portion is arranged in a direction of a driving force by the developing device driving means. The image forming apparatus according to claim 1, wherein the rotation of the image forming unit is locked on a substantially vertical surface. 8. The image forming apparatus according to claim 7, wherein the rotation locking portion locks the rotation of the image forming unit near a line of action of the driving force by the developing device driving unit. 9. The image forming apparatus according to claim 1, wherein the rotation locking portion is provided on the image forming unit transfer means. 10. The image forming apparatus according to claim 1, wherein the rotating body is a photoconductor, and further includes a developing device, a developing device driving unit for driving the developing device, and a photoconductor driving unit for driving the photoconductor. 2. The image forming apparatus according to claim 1, wherein after the photoconductor driving unit starts driving the photoconductor, the developing device driving unit starts driving the developing device. 3. 11. The image forming apparatus according to claim 1, further comprising a thrust locking portion provided near the axis of the rotating body and for positioning the image forming unit in the axial direction of the rotating body. 12. The image forming apparatus according to claim 11, wherein the rotation locking portion and the thrust locking portion are provided on the same side in the axial direction of the rotating body. 13. The image forming unit according to claim 13, wherein the rotating body is a photosensitive member, and further includes a developing unit, a developing unit driving unit for driving the developing unit, and a photosensitive unit driving unit for driving the photosensitive unit. The direction of the rotational moment about the axis of the photoreceptor due to its own weight of the image forming unit is opposite to the direction of the rotational moment about the axis of the sightseeing object by the developing device driving means, and The image forming apparatus according to claim 1, wherein a magnitude of a rotational moment due to a weight of the forming unit is smaller than a magnitude of a rotational moment due to a driving gear of the developing device. 14. An apparatus having a rotating body, which is detachably held in the apparatus main body, and which is mounted on at least one axial end of the rotating body from an axial direction of the rotating body located at an image forming position. The rotating body support member on the main body side is engaged, and the rotating body is positioned at a regular position of the apparatus main body, and
An image forming unit in which the rotation locking portion on the apparatus main body side positions the rotation body in the rotation direction around the axis. 15. The image forming unit according to claim 14, wherein the rotating body is a photoconductor or a developing roller.