Process unit cartridge for an electrophotographic apparatus

A cartridge for use in an electrophotographic apparatus is loaded with various expendable process units which need periodic replacement such as a charger, developing unit, and cleaning unit. At least the charger and cleaning unit are mounted on the cartridge integrally with each other. The cartridge is held in a body of the apparatus in such a manner as to be rotatable between a replaceable position and a set position.

BACKGROUND OF THE INVENTION 
The present invention generally relates to an apparatus for recording an 
image on a paper sheet or similar recording medium by using an 
electrophotographic procedure and, more particularly, to a cartridge 
loaded with various process units which need periodic replacement, e.g., a 
charger, developing unit and cleaning unit and removably installed in the 
body of an electrophotographic apparatus. 
An electrophotographic copier, facsimile machine, laser printer or similar 
apparatus implemented by an electrophotographic process is extensively 
used. This kind of apparatus includes an image carrier in the form of a 
photoconductive element. Arranged around the photoconductive element are 
process units such as a charger, writing unit, developing unit, image 
transferring unit, and cleaning unit. After the charger has uniformly 
charged the surface of the photoconductive element to a predetermined 
polarity, the writing unit writes a desired image in the photoconductive 
element. Then, the developing unit develops the image on the 
photoconductive element to produce a visible image. The visible image is 
transferred by the transferring unit to a paper sheet. The cleaning unit 
cleans the surface of the photoconductive element after such image 
transfer. Subsequently, the charger again charges the surface of the 
photoconductive element to prepare it for another photographic cycle. 
A problem with the prior art apparatus of the type described is that the 
individual process units and parts thereof cannot be replaced, repaired or 
cleaned unless they are attached and detached one by one each time. When 
the photoconductive element, among others, is to be replaced, the various 
process units arranged therearound have to be removed one by one and, 
after the replacement, mounted again one by one. Moreover, in the event 
when the process units, especially the developing unit, are mounted and 
dismounted or when the photoconductive element is replaced, a developer is 
apt to be scattered around from the developing unit or the photoconductive 
element. In light of this, it has been proposed to mount the process units 
which are expendable supplies in a single casing or cartridge, as 
disclosed in Japanese Patent Laid-Open Publication (Kokai) Nos. 62-165670 
and 61-118770 by way of example. Specifically, this prior art scheme 
mounts a photoconductive drum on the body of an electrophotographic copier 
or similar apparatus while mounting the charger, developing unit, cleaning 
unit and other process units on a single cartridge. The cartridge is 
replaced when the developing unit runs out of toner or when the charger or 
the cleaning unit fails. 
An electrophotographic apparatus may be implemented by a developing unit 
including a developing sleeve and an agitator, and a developer container 
loaded with a toner or similar developer and removably mounted on the 
developing unit, as also proposed in the past. This prior art 
implementation, however, has a problem that at the time of replacement of 
the developer container the toner is apt to fall through a toner supply 
opening of the container to contaminate the interior of the apparatus. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a process 
unit cartridge for use in an electrophotographic apparatus which frees one 
from troublesome manipulations otherwise needed to attach and detach 
various process units one by one. 
It is another object of the present invention to provide a process unit 
cartridge for use in an electrophotographic apparatus which prevents a 
developer from being scattered around in the event of attachment and 
detachment of process units and the replacement of a photoconductive 
element. 
It is another object of the present invention to provide a generally 
improved process unit cartridge for an electrophotographic apparatus. 
In accordance with the present invention, in a cartridge for accommodating 
process units of an electrophotographic apparatus having a photoconductive 
element, a charger for charging the surface of the photoconductive 
element, a writing unit for writing an image on the charged surface of the 
photoconductive element to form an electrostatic latent image, a 
developing unit for developing the latent image to form a visible image, 
an image transferring unit for transferring the visible image to a paper 
sheet, and a cleaning unit for cleaning the surface of the photoconductive 
element after the image transfer, the charger again charging the cleaned 
surface of the photoconductive element, at least the charger and cleaning 
unit are mounted on the cartridge integrally with each other. The 
cartridge is held in a body of the apparatus in such a manner as to be 
rotatable between a replaceable position and a set position about a 
fulcrum provided at a side of the cartridge where the cleaning unit is 
positioned.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1 of the drawings, a laser printer belonging to a family 
of electrophotographic apparatuses is shown in which a process unit 
cartridge embodying the present invention is installed. As shown, the 
apparatus has a body 10 and a paper cassette 11 which is removably mounted 
on the body 10 and loaded with a stack of paper sheets 12. A paper sheet 
12 fed from the paper cassette 11 by a feed roller 13 as indicated by an 
arrow A is guided by a guide plate or similar member until it abuts 
against a pair of register rollers 14. After a temporary halt, the paper 
sheet 12 is again driven by the register rollers 14 at a predetermined 
timing toward an image carrier which is implemented as a photoconductive 
drum 15. 
The drum 15 is rotated by a drive mechanism, not shown, in a clockwise 
direction as viewed in the figure. A charger 16 uniformly charges the 
surface of the drum 15 being rotated, and then a writing unit 17 scans the 
surface of the drum 15 by a laser beam for thereby electrostatically 
forming a latent image thereon. A developing unit 18 develops the latent 
image to produce a visible image on the drum 15. A transferring unit 19 
transfers the visible image from the drum 15 to the paper sheet 12 which 
has been driven toward the drum 15 as stated previously. A fixing unit 20 
heats and presses the paper sheet 12 carrying the visible image thereon so 
as to fix the visible image. Then, a switching device 21 selects a 
transport path 22 for discharging the paper sheet 12 with the fixed image 
to a face-down discharging section 23, as indicated by an arrow B. 
Alternatively, the switching device 21 may be so positioned as to direct 
the paper sheet 12 straight to a face-up discharging section 24. A 
cleaning unit 25 has a cleaning blade 26 which cleans the drum 15 to 
remove the developer which remains thereon after the image transfer. The 
removed developer is collected in a tank 27. 
As shown in FIG. 2, the printer body 10 is made up of an upper part 30 and 
a lower part 31. The upper body part 30 is movable or openable about a 
shaft 29 away from the lower body part 31. The upper body part 30 has a 
lug 32 which extends downward from a member accommodated in the upper part 
30. 
Referring to FIGS. 3 and 4, an image forming case 33 incorporated in the 
lower body part 31 is shown. The image forming case 33 has a pair of lugs 
35 at one side thereof and a locking lever 36 at the other side. Each lug 
35 is formed with an opening 34 for receiving a shaft, while the locking 
lever 36 is constantly biased clockwise as viewed in FIG. 4. After the 
image forming case 33 has been rotatably positioned in the lower body part 
31 by the shaft which has been received in the openings of the lugs 35, 
the locking lever 36 is engaged with a member provided in the lower body 
part 31 to thereby fix the case 33 in place. As shown in FIGS. 3 and 4, 
the drum 15 is positioned at the center of the image forming case 33. The 
developing unit 18 (see FIG. 1) is positioned at the right-hand side of 
the case 33 with respect to the drum 15, while a top-open bore 37 having a 
generally rectangular parallelepiped configuration is defined at the 
left-hand side of the case 33. The developing unit 18 has a developing 
chamber 38 thereinside, as well known in the art. An agitator 39, a supply 
roller 40 and a developing roller 41 are disposed in the developing 
chamber 38 in order to supply a developer 42 from the chamber 38 to the 
drum 15. The upper portion of the developing chamber 38 is delimited by a 
semicylindrical wall 43. An elongate opening 44 is formed through the 
semicylindrical wall 43 to communicate the developing chamber 38 to the 
outside. A pair of unlocking members 45 are affixed to the top of the 
image forming case 33 while protruding into the semicircular recess which 
is defined by the wall 43. Guide members 46 are located face to face in 
the top-open bore 37, and each is supported by a shaft. A single bucket 47 
is also disposed in the bore 37 and rotatably supported on the same shafts 
as the guide members 46. Coil springs 48 are individually wound round the 
shafts to bias the bucket 47 counterclockwise as viewed in FIG. 4. A lug 
49 extending out from the bucket 47 abuts against a shoulder 50 of the 
image forming case 33, whereby the counterclockwise movement of the bucket 
47 is restricted. As shown in FIG. 4, the bucket 47 is held in a position 
tilted by the same angle .theta. as the guide members 46 to the vertical. 
In FIG. 3, the reference numeral 51 designates an elongate rectangular 
opening formed through the image forming case 33 above the drum 15. 
Referring to FIG. 5, a process unit cartridge embodying the present 
invention is shown and generally designated by the reference numeral 55. 
The cartridge 55 is mounted on the image forming case 33, as follows. As 
shown, a developer container 54 is mounted on the right-hand side of the 
cartridge 55, while the cleaning unit 25 (see FIG. 1) is provided on the 
left-hand side. A recess 56 is formed in each of opposite walls of the 
cleaning unit 25. Each recess 56 has a straight channel portion 57 and a 
circular portion 58 contiguous with the straight portion 57. The cartridge 
55 has a semicylindrical wall section 59 for receiving the developer 
container 54. An opening 60 is formed through the wall section 59 for 
supplying the developer, as will be described. The opening 60 has the same 
dimensions as the previously mentioned opening 44 and is elongate as the 
opening 44. Seal members 61 are implemented by sponge and adhered to the 
wall section 59 at opposite sides of the opening 60. Container retaining 
sections 62 are positioned at opposite sides and outwardly of the wall 
section 59. Each container retaining section 62 has a semicircular 
top-open mating portion 63 and two elastic portions 64 extending obliquely 
downward toward the mating portion 63. At each side of the wall section 
59, a cruciform hole 65 and a channel-like hole 66 are formed side by 
side. 
Legs 67 extend downward from opposite ends of the right-hand side of the 
cartridge 55 as viewed in FIG. 5. When, the cartridge 55 is placed on a 
table, for example, the legs 67 will cooperate with the cleaning unit 25 
to maintain the cartridge 55 in a stable position. Further, an opening 68 
for writing an image is formed through the cartridge 55 and will align 
with the opening 51 of the image forming case 33 when the cartridge 55 is 
mounted on the case 33. Although not shown in FIG. 5, the charger 16 is 
affixed to the inner periphery of the cartridge 55 in parallel with the 
opening 68. When the cartridge 55 is mounted on the image forming case 33, 
the charger 16 will enter the case 33 via the opening 51 to face the drum 
15, as shown in FIG. 1. 
A locking lever 70 is rotatably mounted on the cartridge 55. As shown in 
FIG. 6, the locking lever 70 is made up of a pair of spaced lever portions 
71, a shaft portion 72 interconnecting the lever portions 71, and a knob 
portion 73 extending out from the shaft portion 72. Each lever portion 71 
has a notch 74 at the lower end and a lug 75 at the upper end. The locking 
lever 70 is supported at opposite ends thereof by a pair of frames 76 
which form a part of the cartridge 55, the knob portion 73 protruding to 
the outside of the frames 76. A spring 77 is wound around each end of the 
shaft portion 72 which is supported by the associated frame 76. The spring 
77 is anchored at one end to a stub 78 extending from the lever portion 71 
and at the other end to a stop 79 extending from the frame 76. In this 
configuration, the locking lever 70 is constantly biased by the springs 77 
clockwise as viewed in FIG. 6 and is stopped by the stops 79. FIG. 6 shows 
the cartridge 55 in a position mounted on the image forming case 33 and, 
in this position, the notches 74 are mated with an end 80 (see FIG. 4) of 
the case 33 with the lever portions 71 being spaced apart from the 
associated stops 79. 
As shown in FIG. 5, the developer container 54 for supplying the developer 
42 to the developing unit 18 has a cylindrical body portion 82, and caps 
83 mounted on opposite ends of the body portion 82. The body portion 82 is 
cut in a plane parallel to the axis of thereof to form a flat surface 84 
having a predetermined width. A hole is formed through the flat surface 84 
adjacent to either end of the developer container 54 and is closed by a 
plug 85. A handle 86 extends radially outward from a part of the periphery 
of the body portion 82. As shown in FIG. 7, an elongate opening 87 is 
formed through and along the axis of the container 54 and is provided with 
the same dimensions as the previously stated openings 60 and 44. The 
opening 87 is closed by a seal 88 as indicated by a dash-and-dots line in 
FIG. 7. One end (right end as viewed in FIG. 7) of the seal 88 is somewhat 
extended and fitted on the handle 86. As shown in FIG. 5, each cap 83 has 
a radially extending lug 89, a circumferentially extending rail-like 
locking portion 90, and a stub 91 which aligns with the center of the body 
portion 82 when the cap 83 is affixed to the body portion 82. Further, as 
shown in FIG. 7, each cap 83 has a locking pawl 92 which is formed by 
cutting out the periphery of the cap 83 in the form of a letter L and then 
slightly raising it. 
In assembly, as shown in FIG. 5, the developer conainer 54 is loaded on the 
semicylindrical wall section 59 of the cartridge 55 from above. 
Specifically, the stubs 91 of the container 54 are individually engaged 
with the mating sections 63 while forcing the elastic portions 64 open. 
After the passage of the stubs 91, the elastic portions 64 regain their 
original position to positively retain the stubs 91 in the container 
retaining portions 62. Then, the lugs 89 of the caps 83 are abutted 
against the upper surface of the cartridge 55. This causes the locking 
pawls 92 of the caps 83 to individually enter the cruciform holes 65 of 
the wall section 59 of the cartridge 55 until their tips abut against the 
edges of the laterally extending parts of the holes 65, as shown in FIGS. 
8 and 9. In this condition, the developer container 54 is prevented from 
rotating on the wall section 59 in directions indicated by a double-headed 
arrow in FIG. 8. At the same time, the developer container 54 is 
positioned in such a manner as to close the opening 87. In FIG. 8, the 
reference numeral 94 designates a coil spring which is accommodated in the 
body portion 82 of the developer container 54 and caused to vibrate for 
the purpose of fully emptying the container 54. 
Subsequently, the seal 88 fitted on the handle 86 is removed and then torn 
off. However, since the opening 87 of the developer container 54 is closed 
by the seal member 62 of the wall section 59, the developer 42 in the 
container 54 is prevented from leaking therethrough. 
The cartridge 55 loaded with the developer container 54 as stated above is 
mounted on the printer body 10, as follows. As shown in FIG. 10, the 
cartridge 55 is inserted into the image forming case 33 in a direction 
indicated by an arrow D, while being inclined by the angle .theta. to the 
vertical with the cleaning unit 25 being lowest. As the cartridge 54 is 
inserted in the direction D, the straight portions 57 of the recesses 56 
individually mate with the guide members 46. As the cartridge 54 is 
inserted deeper into the direction D, it is fully received in the bucket 
47 with the guide members 46 entering the circular portions 58 of the 
recesses 56. In this condition, the cartridge 55 is held in a replaceable 
position and rotatable in a direction indicated by an arrow E. Then, the 
cartridge 55 is rotated together with the bucket 47 about the guide 
members 46 in the direction E and against the action of the springs 48, 
the resulting position being shown in FIG. 11. Subsequently, the notches 
74 of the locking lever 70 are mated with the end 80 of the image forming 
case 33. As a result, the unlocking members 45 push the locking pawls 92 
out of the cruciform holes 65, as shown in FIG. 12. The developer 
container 54 is now free to rotate. As the upper body part 30 is closed, 
the downwardly extending lug 32 (FIG. 2) presses the handle 86 downward to 
automatically rotate the developer container 54 from the closed position 
to the open position shown in FIG. 11. As shown in FIG. 13, in the open 
position of the developer container 54, the opening 87 is uncovered and 
aligned with the opening (FIG. 3) via the opening 60, whereby the 
developer 42 is fed from the container 54 to the developing chamber 38 
(FIG. 4). On the other hand, the locking portions 90 of the container 54 
enter the holes 66 of the cartridge 55 and face the lugs 75 of the lever 
portions 71 of the locking lever 70, as shown in FIG. 13. In this 
position, the locking portions 90 prevent the locking lever 70 from 
unlocking the developer container 54. 
While the seal 88 has been described as being torn off while the developer 
container 54 is held in the closed position, it may be done so after the 
container 54 has been brought to the open position to align the openings 
87 and 70, as shown in FIG. 13. 
When the developer container 54 has run out of the developer 42, the 
cartridge 55 is replaced with a new cartridge by the following procedure. 
Specifically, after the upper body part 30 has been opened away from the 
lower body part 31, the handle 86 is raised to rotate the developer 
container 54 from the open position shown in FIG. 13 to the closed 
position shown in FIG. 12. As a result, the opening 87 of the developer 
container 54 is brought out of alignment with the opening 44. Then, the 
knob 73 is raised to rotate the locking lever 70 to release the notches 74 
from the case end 80. In this condition, the cartridge 55 is bodily 
rotated about the guide members 46 from the set position to the 
replaceable position. This releases the locking pawls 92 from the 
unlocking members 45 and causes them to engage with the cruciform holes 65 
again, thereby preventing the developer container 54 from rotating. 
Thereafter, the cartridge 55 is pulled out from the image forming case 33 
in the direction opposite to the direction D shown in FIG. 10. A new 
cartridge 55 loaded with a full developer container 54 beforehand is 
mounted on the image forming case 33 by the previously stated procedure. 
Finally, the upper body part 30 is closed to automatically supply a 
developer 42 from the fresh container 54 into the developing chamber 38. 
As stated above, in the illustrative embodiment, the cartridge 55 cannot be 
rotated to the replaceable position unless the developer container 54 is 
rotated to the closed position by the locking device. This is successful 
in preventing one from rotating the cartridge 55 with the opening 87 being 
kept open and, therefore, in preventing the developer 42 from being 
scattered around through the opening 87. Also, when the cartridge 55 is 
brought to the replaceable position, the locking device inhibits the 
developer container 54 from rotating to the open position and thereby 
eliminates the leakage of the developer 42 through the opening 87. Since 
the toner collecting opening of the cleaning unit 25 faces upward while 
the cartridge 55 is in the replaceable position, the used cartridge 55 is 
replaced without the developer 42 being scattered around. 
In the illustrative embodiment, the developer container shown in FIGS. 5 
and 7 is mounted on the cartridge 55 and then bodily rotated between the 
closed and open positions. Alternatively, as shown in FIG. 14, the 
developer container 54 may be composed of a container body 100 and a cover 
101 which is openable. As shown in FIG. 15, the elongate opening 87 is 
formed through the container body 100 and is surrounded by seal members 
102 which are adhered to the container body 100. The developer 42 is 
filled in the container body 100. The cover 101 is rotatably mounted on 
the container body 100 while covering the entire circumference at opposite 
ends of the latter and one half of the circumference at the intermediate 
between the opposite ends. The cover 101 has the handle 86 extending 
radially outward from the intermediate portion, the lugs 89 extending 
radially outward from the opposite ends, and the rail-like locking 
portions 90 each extending along the circumference. Further, the cover 101 
has the stubs 91 aligning with the axis of the container body 100 and 
pawls 92 and an axially extending elongate opening 103. 
As in the previous embodiment, the developer container 54 is mounted on the 
wall section 59 of the cartridge 55 with the stubs 91 being retained by 
the container retaining portions 62. The lugs 89 of the developer 
container 54 are abutted against the upper surface of the cartridge 55. In 
this condition, the pawls 92 enter the individual cruciform holes 65 of 
the wall section 59 until their tips engage with the edges of the 
laterally extending parts of the holes 65. As a result, the cover 101 is 
prevented from rotated clockwise as viewed in the figure on the wall 
section 59. In this closed position of the cover 101, the opening 87 of 
the container body 100 is not aligned with the opening 103, as shown in 
FIG. 15. However, when the cartridge 55 is mounted on the image forming 
case 33, the unlocking members 45 press the pawls 92 to render only the 
cover 101 rotatable from the close position to the open position. When the 
cover 101 is rotated to the open position. When the cover 101 is rotated 
to the open position, the openings 87 and 103 are brought into alignment, 
as shown in FIG. 16. 
Referring to FIG. 17, a laser printer incorporating an alternative 
embodiment of the process unit cartridge in accordance with the present 
invention is shown. In the figures, the same components and structural 
elements are designated by like reference numerals, and redundant 
description will be avoided for simplicity. As shown, the printer body 10 
is also made up of the upper body part 30 and lower body part 31. 
Additionally, the image forming case 33 comprises an opening 110 similar 
to the opening 34 shown in FIG. 4. As shown in FIG. 18, the upper body 
part 30 is openable away from the lower body part 31. Specifically, assume 
that the paper sheet 12 has jammed the printer. Then, as shown in FIG. 19, 
the upper body part 30 is opened and the image forming case 33 is bodily 
rotated counterclockwise as viewed in the figure, whereby a paper 
transport path 111 defined below the case 33 is uncovered. Subsequently, a 
stand 112 interconnecting the image forming case 33 and lower body part 31 
is extended to support the case 33 in the rotated position. This allows 
the jamming paper sheet, 12a in FIG. 19, to be removed with ease. The 
image forming case 33 is loaded with the photoconductive element 15 which 
is provided with a knob 113, as well as the charger, 16, developing unit 
18, and cleaning unit 25. 
In this particular embodiment, the cartridge 55 has the charger 16 and 
cleaning unit 25 formed integrally therewith. As shown in FIG. 20, the 
cartridge 55 is provided with bearing portions 114 at opposite sides of 
one end thereof which is adjacent to the cleaning unit 25. Each bearing 
portion 114 is composed of a ring portion 114a and spaced parallel 
portions 114b extending from opposite ends of the ring portion 114a. As 
also shown in FIG. 20, the image forming case 33 is provided with stubs 
115 on facing inner surfaces thereof. Each stub 115 is cut vertically at 
opposite sides thereof to form flat surfaces 115a. As shown in FIG. 21, 
the cartridge 55 is mounted on the image forming case 33 by mating the 
bearing portions 114 with the stubs 115, i.e., by mating the ring portions 
114a with the hubs 115 via the parallel portions 114b. In this condition, 
the cartridge 55 is held in the replaceable position with the collecting 
tank 27 having its opening 116 directed upward. The cartridge 55 in the 
replaceable position is ready to rotate about the stubs 115 to a set 
position which is shown in FIG. 22. As shown in FIG. 22, the developing 
unit 18 has a developing case 117 in which a developing roller 118 and a 
supply roller 119 are disposed. A spring 120 is preloaded between the 
image forming case 33 and the developing case 117. After the developer 
container 54 has been mounted on the developing case 117, the developing 
case 117 is urged toward the drum 15 by the spring 120 resulting in the 
developing roller 118 being urged against the developing roller 118. 
The upper body part 30 is opened, as shown in FIG. 18. Then, the cartridge 
55 is rotated from the set position shown in FIG. 22 to the replaceable 
position shown in FIG. 21. As a result, the cleaning unit 25 is spaced 
apart from the drum 15 while the charger 16 and the like are also moved 
away from the drum 15, whereby the drum 15 is uncovered. In this 
condition, one can readily mount or dismount the drum 15 by holding the 
knob 113 and without the need for removing various process units arranged 
around the drum 15. While the cartridge 55 is removed, the opening 116 of 
the collecting tank 27 is directed upward so that the developer 42 is 
prevented from being scattered around. 
The developing unit 18 is movable away from the drum 15 against the action 
of the spring 120. When the developing unit 18 is so moved, the drum 15 is 
freely movable within the image forming case and, therefore, it is easy to 
remove. 
Referring to FIGS. 23 and 24, another alternative embodiment of the present 
invention is shown. In the figures, the same components and structural 
elements are designated by like reference numerals, and redundant 
description will be avoided for simplicity. As shown in FIG. 23, in this 
particular embodiment, a crossbar 121 is disposed in the image forming 
case 33 and held in a horizontal position. The crossbar 121 extends to the 
side periphery of the cartridge 55 and that of the developing unit 18. A 
projection 122 is provided on the side periphery of the developing unit 
18, and one end 121a of the crossbar 121 is abutted against the lug 122. A 
projection 123 is provided on the side periphery of the cleaning unit 25 
of the cartridge 55 and spaced from the other end 121b of the crossbar 
121. As shown in FIG. 24, when the cartridge 55 is rotated from the set 
position to the replaceable position, the projection 123 abuts against the 
end 121b of the crossbar 121 and thereby urges the crossbar 121 to the 
right in the figure. The end 121a of the crossbar 121 in turn urges the 
projection 122 with the result that the developing unit 18 is retracted 
away from the drum 15 against the action of the spring 120. In this 
manner, the crossbar 121 further promotes the ease of replacement of the 
drum 15. 
Referring to FIGS. 25 and 26, another alternative embodiment of the present 
invention is shown. In the figures, the same components and structural 
elements are designated by like reference numerals, and redundance 
description will be avoided for simplicity. As shown in FIG. 25, an 
articulated foldable stand 124 interconnects the cartridge 55 and image 
forming case 33. One end 124a of the stand 124 is removably affixed to or 
simply abutted against the cleaning unit 25. In this configuration, when 
the cartridge 55 is rotated to the replaceable position as shown in FIG. 
26, the stand 124 is unfolded to maintain the cartridge in the replaceable 
position. This allows the drum 15 to be replaced with safetiness. 
FIG. 27 indicates another specific configuration of the means for holding 
the cartridge 55 in the replaceable position. As shown, the cleaning unit 
25 portion of the cartridge 55 is provided with a recess 125, while the 
image forming case 33 is provided with a leaf spring 126 at one end 33a 
thereof. When the cartridge 55 is rotated to the replaceable position, the 
recess 125 mates with the tip of the leaf spring 126 to maintain the 
cartridge 55 in the replaceable position. Such a configuration is also 
successful in promoting safety replacement of the drum 15. 
As shown in FIG. 28, the recess 125 of the cartridge 55 may be replaced 
with a lug 127. Specifically, the lug 127 is provided in the cleaning unit 
25 portion of the cartridge 55. As the cartridge 55 is rotated to the 
replaceable position, the lug 127 engages with the tip of the leaf spring 
126 to hold the cartridge 55 in the replaceable position. If desired, the 
leaf spring 126 may be replaced with an elastic portion which is formed 
integrally with the image forming case 33 and engageable with the recess 
125 or the lug 127. 
In summary, in accordance with the present invention, at least a charger 
and a cleaning unit can be mounted and dismounted integrally with each 
other. This allows various process units arranged around a photoconductive 
element to be replaced, repaired or cleaned without the process units 
being attached and detached one by one. Also, the photoconductive element 
can be replaced without the need for attaching and detaching the process 
units one by one. In the event of replacement, repair or cleaning of the 
process units or replacement of the photoconductive element, a cartridge 
is rotated to a replaceable position where it it spaced apart from the 
process units. This frees the photoconductive element from scratches and, 
at the same time, directs a toner collecting opening of the cleaning unit 
upward to thereby positively prevent a toner from being scattered around. 
Various modifications will become possible for those skilled in the art 
after receiving the teachings of the present disclosure without departing 
from the scope thereof.