Electrophotographic copying apparatus

The present invention is an electrophotographic copying apparatus which includes a group of switches disposed along the path of the copy paper. These switches are so arranged as to control the functions of corona charging, exposure and aligning the forward edge of the image formed on the photoreceptor with the leading edge of the copy paper, while the starting of the transfer device and the function of the copy paper separation device are controlled through a control cam which is driven by actuating signals produced by one of these switches. Since the developing and transfer functions are arranged to be suspended by a drum cam rotating as one unit with the photoreceptor drum, the possibility of copy paper jamming is decreased to a large extent through reduction of the number of switches employed, while undesirable developing and transfer at the slot portion or seam portion of the photoreceptor are advantageously eliminated.

The present invention relates to a copying apparatus, and more 
particularly, to an electrophotographic copying apparatus of the transfer 
type. 
Conventionally, in a transfer type electrophotographic copying apparatus 
based on a xerographic or similar system, an electrostatic latent image of 
the original to be copied is formed in a known manner on a photoreceptor 
layer disposed on the outer periphery of a rotatable photoreceptor drum, 
and is subsequently developed into a visible toner powder image, which is 
then transferred onto a transfer material such as copy paper sheet. The 
toner powder image thus transferred is further fixed onto the transfer 
material, for example, by heat fusing to obtain copied images. 
The known transfer type electrophotographic copying apparatus of the above 
described type consequently includes various processes such as preliminary 
charging the photoreceptor surface of the photoreceptor drum by a corona 
charger, projecting the light images of the original through an optical 
system onto the photoreceptor surface for the formation of the latent 
image thereon, developing the latent image to obtain the visible toner 
image, transferring the toner powder image onto the copy paper sheet, 
separating the copy paper sheet from the photoreceptor drum after the 
transfer, cleaning the photoreceptor surface after the separation of the 
copy paper sheet, and heating the separated copy paper sheet for fixing 
the copied image thereon, in which processes it is necessary that the 
forward edge of the image formed on the photoreceptor surface coincides 
with the corresponding leading edge of the copy paper sheet to obtain the 
copied image of the original on a predetermined position of the copy paper 
sheet. Especially, in cases where the photoreceptor drum has an axially 
formed slot so that a sheet-like photoreceptor housed in the drum can be 
led through the slot around the drum outer periphery for necessary 
replacement of the photoreceptor, it is essential to prevent the image of 
such a discontinuity i.e., the slot or seam of the photoreceptor, from 
being formed in the copied image. Additionally, should jamming of the copy 
paper sheet arise in any of the above described processes, such trouble 
must immediately be detected for quick remedy. 
Although various electrophotographic copying apparatuses provided with 
arrangements for synchronizing the image with the copy paper sheet, and 
also for preventing jamming of the copy paper sheet have been 
conventionally proposed, there have been none that fully meet the 
requirements. 
Accordingly, an essential object of the present invention is to provide an 
electrophotographic copying apparatus of the transfer type in which 
jamming of copy paper sheet is positively detected through a timed 
relation between a drum cam and a switch means disposed on the copy paper 
path. 
Another important object of the present invention is to provide an 
electrophotographic copying apparatus of the above described type in which 
each of the copying processes are effected in accurate synchronization 
with the alignment between the forward edge of the image formed on the 
photoreceptor and the leading edge of the copy paper assured by a simple 
control circuit through the employment, of a control cam, other than the 
drum cam, rotating independently of the drum cam, and in which developing 
and transferring at a discontinuity, i.e., at the slot of the 
photoreceptor drum or at a seam of the photoreceptor are positively 
prevented, with substantial elimination of the disadvantages inherent in 
the conventional electrophotographic copying apparatuses of this kind. 
A further object of the present invention is to provide an 
electrophotographic copying apparatus of the above described type which is 
accurate in functioning and simple in construction, with a consequent 
reduction in manufacturing cost. 
According to a preferred embodiment of the present invention, the 
electrophotographic copying apparatus includes a group of switches 
disposed along a path of the copy paper. These switches are so arranged as 
to control the functions of corona charging, exposure and aligning the 
forward edge of the image formed on the photoreceptor with the leading 
edge of the copy paper, while the starting of the transfer device and the 
function of the copy paper separation device are controlled through a 
control cam which is driven by actuating signals produced by one of these 
switches. Meanwhile, since the developing and transfer functions are 
arranged to be suspended by a drum cam rotating as one unit with the 
photoreceptor drum, the possibility of copy paper jamming is decreased to 
a large extent through reduction of the number of switches employed, while 
undesirable developing and transfer at the slot portion or seam portion of 
the photoreceptor are advantageously eliminated.

Before the description of the present invention proceeds, it is to be noted 
that like parts are designated by like reference numerals throughout 
several views of the accompanying drawings. 
Referring to FIGS. 1 to 20, there is shown in FIG. 1 a transfer type 
electrophotographic copying apparatus 1 of the invention which comprises a 
photoreceptor drum 2 having a photoreceptor surface or photoreceptor layer 
4 on the outer periphery thereof and secured on a rotatable shaft 3 
suitably journalled in the frame (not shown) of a housing G of the copying 
apparatus so as to rotate in the direction shown by the arrow "a" for 
causing the photoreceptor surface 4 to sequentially pass various 
processing stations such as a corona charging station provided with a 
corona charger 70, an exposure station E, a developing station having a 
developing device 28, a transfer and charging station with a transfer 
corona charger 41, a copy paper separating station provided with a 
separating claw 42, a residual charge erasing station having a first 
eraser lamp 46 and an erasing charger 47 and a cleaning station provided 
with a cleaning device 48 for removing residual toner from the 
photoreceptor surface 4, each of these stations is disposed along the path 
of the photoreceptor surface 4. On the upper portion of the apparatus 
housing G, there is a horizontally, reciprocating transparent platform 19 
for placing an original 23 to be copied thereon. Light images of the 
original 23 illuminated by an exposure lamp 21 are directed through 
reflecting mirrors 24, 25, 26 and 27 as shown by the arrowed line c onto 
the photoreceptor surface 4 at the exposure station E. 
The photoreceptor drum 2 includes the photoreceptor 4 in sheet-like form 
stored on a supply roll 2a housed within the drum 2 and led therefrom 
around the outer periphery of the same drum 2 via an idle roller 2c and 
through a slot 2d axially formed in the drum surface so as to be wound 
onto a takeup roll 2b also housed within the drum 2. This enables the 
photoreceptor 4 on the drum 2 to be replaced when wound onto the takeup 
roll 2b. It is needless to say that the photoreceptor 4 may be modified to 
be wound around the outer periphery of the drum 2 and tightly held thereon 
with the opposite edges thereof fixed by an electrically conductive tape 
(not shown) or the like. 
Referring particularly to FIGS. 2 and 3, the drum shaft 3 has its end 
portion 3a extending from the photoreceptor drum 2. On this end portion 
3a, a drum driving gear 5 and a drum cam 6 are fixedly mounted in a spaced 
relation to each other. A gear 7 coupled to a main motor (not shown) 
through a transmission means engages the drum driving gear 5 for rotating 
the drum 2, the drum shaft 3 and the drum cam 6 simultaneously as one 
unit. As the drum cam 6 rotates, switches SD1, SD2, SD3, SD4, and SD5 
disposed around the outer periphery of the drum 2 are sequentially 
actuated in a manner mentioned later. On the shaft 3 in a position between 
the drum driving gear 5 and the drum cam 6, there is rotatably mounted a 
control cam driving gear 8, with a control cam 9 frictionally contacting 
said gear 8. The gear 8 is driven by a gear 10 through a transmission 
mechanism (not shown) independent of the shaft 3 and rotates the control 
cam 9 for actuating switches SC1 and SC2 disposed in the path of control 
cam 9. On one surface adjacent to the outer periphery of the control cam 9 
and facing the drum cam 6, there are fixedly mounted a separating claw 
lever 9a, a switch actuating plate 9b through a shaft 11 and a latch 
actuating pin 9c (FIG. 3). On while on the other surface adjacent to the 
outer periphery of the control cam 9 and facing the control cam driving 
gear 8, there is pivotally disposed through a pin 12a a control cam 
restricting lever 12 of approximately L shape in a position confronting 
the separating claw lever 9a of the control cam 9, with the drum shaft 3 
being located therebetween. A spring 13 is connected between one end 12b 
of the control cam restricting lever 12 and the control cam 9 for urging 
the lever 12 counterclockwise (as viewed in FIG. 3). The end 12b of the 
lever 12 normally engages an engaging portion 15a extending in a direction 
parallel to the drum shaft 3 from an engaging lever 15 secured to a 
plunger of a solenoid 14 which is disposed in the vicinity of the outer 
periphery of the control cam driving gear 8. In this state, since a latch 
gear 16 integrally formed with the gear 8 is disengaged from a latch 
portion 12c at the other end of the control cam restricting lever 12, the 
control cam 9 remains stationary at an initial stage. When the solenoid 14 
is energized, the engaging lever 15 is displaced in the direction of the 
arrow K, the engaging portion 15a of the lever 15 is disengaged from the 
end 12b of the control cam restricting lever 12, and the lever 12 rotates 
counterclockwise by the urging force of the spring 13, whereby the latch 
portion 12c of the lever 12 engages the latch gear 16 for positively 
transmitting the rotation of the driving gear 8 to the control cam 9. As 
is clear from FIG. 3, if solenoid 14 is denergized when control cam 9 
completes one revolution, then the end 12b of restricting level 12 engages 
the engaging portion 15a of lever 15 which disengages latch portion 12c 
from latch gear 16. Thus the control cam 9 is no longer rotated by driving 
gear 8. 
Still referring to FIGS. 2 and 3, in a position above the control cam 
restricting lever 12, an operating lever 17 for actuating a developing 
device operating switch SK1 is pivotally supported through a pin 17a by 
the frame of the copying apparatus. A supporting lever 18 for holding the 
operating lever 17 in a predetermined position is also supported by the 
frame through a pin 18a. The levers 17 and 18 are normally forced by 
spring means (not shown) in directions shown by arrows R and S 
respectively, with the lever 17 being located in a position shown by the 
dashed line, while the lever 18 is positioned as indicated by the solid 
line. When the switch actuating plate 9b contacts the operating lever 17 
as the control cam 9 rotates, the operating lever 17 rotates clockwise, 
and an engaging portion 17b extending at right angles from one edge of the 
lever 17 in a direction parallel to the shaft 3 engages at the lower edge 
thereof with a notch 18b formed in the central portion of the supporting 
lever 18 so as to hold the operating lever 17 in a position indicated by 
the solid line for maintaining the latch switch SK1 in the on state. 
Meanwhile, a pin 6a secured to the surface of the drum cam 6 opposite the 
control cam 9 engages the other end of the supporting lever 18 through 
rotation of the drum cam 6 for rotating the lever 18 clockwise to a 
position shown by the dashed line. This releases the operating lever 17 
which returns to the original position shown by the dashed line to turn 
off the latch switch SK1. 
Referring back to FIG. 1, in a position above the photoreceptor drum 2, 
there is disposed the corona charger 70 having a wire electrode 70a 
disposed in a stabilizing plate for imparting a negative charge to the 
photoreceptor 4. An exposure lamp 21 is suitably cooled by a cooling fan 
20 and fixedly disposed below the transparent platform 19. Light rays C 
from the exposure lamp 21 are directed to a predetermined position of the 
platform 19, which moves in the direction of the arrow "b" at a speed 
equal to the rotational speed of the photoreceptor drum 2, and are 
projected onto the original 23 placed on the surface of a light 
transmitting plate 22 of the platform 19. The light rays "c" reflected 
from the original 23 are then directed onto the photoreceptor surface 4 
through the reflecting mirror 24, the mirror lens assembly 25, the 
reflecting mirrors 26 and 27 which are suitably inclined for the formation 
of the image of the original 23 on the photoreceptor surface 4. Since the 
magnification of the mirror lens assembly 25 is to be one, the image to be 
formed on the photoreceptor surface 4 is equal in size to the original 23. 
On the photoreceptor surface 4, the negative charge is erased at the 
portions where the light intensity from the mirror 27 is high, i.e., where 
the density of the original 23 is low, while the same negative charge 
remains only at the portion where the light intensity from the mirror 27 
is low, i.e., where the density of the original 23 is high. Thus an 
electrostatic latent image of the original 23 is formed on the 
photoreceptor surface 4. 
In FIG. 1, the developing device 28 disposed at the left hand side of the 
photoreceptor drum 2 includes a toner tank 29, a toner supplying roller 
(not shown), a developing material diffusing roller 28a, a developing 
material stirring roller 28b, and a developing or magnetic roller 30 
having a rotatable outer cylinder 30a of weak magnetizable material and 
stationary magnets (not shown) incorporated in the cylinder 30a which is 
disposed adjacent to the drum 2 in spaced relation to the drum 2. The 
toner particles housed in the toner tank 29 are supplied at a 
predetermined rate into the magnetizable carrier material such as iron 
filings or the like to form the developing material in which the toner 
particles are triboelectrically charged to `positive` by the carrier 
material through rotation of the rollers 28a and 28b. The developing 
material including the toner particles thus charged to `positive` polarity 
form magnetic brush bristles on the outer cylinder 30a. As the cylinder 
30a rotates, the toner particles adhere to the portion of the 
photoreceptor surface 4 which is negatively charged for developing the 
electrostatic latent image into a visible toner powder image. It should be 
noted here that the developing device 28 is further provided with biasing 
voltage timing control means for charging only the latent image forming 
portion, without charging the non-latent image forming portion of the 
photoreceptor 4, by arranging the corona charger 70 to be turned on or off 
depending on the length of copy paper. More specifically, the biasing 
voltage means for applying a developing bias having the same polarity as 
the latent image to the toner particles is adapted to be variable for 
variation of biasing voltage at the image formed portion and the non-image 
formed portion through a change-over means associated with the copying 
operation for preventing the toner particles from adhering to the 
non-image formed portion. For the above described purpose, in FIG. 1, the 
corona charger 70 is, for example, formed into slit-like configuration at 
its discharge opening (not shown), with a shutter member (not shown) which 
moves in association with the copying operation being pivotally disposed 
between the discharge opening and the photoreceptor surface 4 for 
selectively opening and closing the discharge opening of the corona 
charger 70 by the operation of the shutter member so as to control the 
charged length on the photoreceptor surface 4. The magnetic roller 30 is 
provided with a variable bias applying means mentioned later. Thus only 
the image forming portion of the photoreceptor surface 4 of the drum 2 
rotating counterclockwise is charged in the region -700 to 31 800 V by the 
corona charger 70, without charging the non-image forming portion of the 
same photoreceptor surface 4. 
It is to be noted that the concept of the above described arrangement for 
preventing toner from adhering to the non-image forming portion is not 
limited in its application to magnetic brush developing, but may be 
applicable to the known cascade developing, in which case, the biasing 
voltage to be applied to a developing electrode opposite the photoreceptor 
surface 4 may be adapted to be variable. 
In the foregoing arrangement, the degree of variation of the biasing 
voltage is determined taking into account the physical properties of the 
toner and the photoreceptor in order not to impart a coulomb force 
contributing to adhesion therebetween due to the potential of the 
non-image forming portion (such potential may generally be regarded as 
zero). One example of circuit construction for the above described biasing 
voltage control means for charging only the latent image forming portion, 
without charging the non-latent image forming portion of the photoreceptor 
will be described in more detail later with reference to FIGS. 13 and 14. 
Still referring to FIG. 1, at the left hand side of the apparatus housing 
G, there is rotatably disposed a spindle 31 on which copy paper 32 is 
wound in a roll form. The leading edge 32a of copy paper 32 is held 
between a pair of copy paper feeding rollers 33a and 33b, and the copy 
paper 32 from the roll is fed in the direction of the arrow "e" at the 
same speed as the circumferential speed of the photoreceptor drum 4 as the 
rollers 33a and 33b are rotated. A guide plate 34 extending downward is 
disposed along the transportation path of the copy paper 32, with cutter 
means K which has blades member 35a and 35b being provided between the 
rollers 33a and 33b and the guide plate 34. Along the guide plate 34 
curving downwardly toward the photoreceptor drum 4, three transportation 
rollers 36a, 36b and 36c are disposed to form an approximately triangular 
path, with a belt 37 being directed at proper tension around the roller 
pairs 36a, 36b and 36c for transporting the copy paper 32 in the direction 
of the arrow "e" between the belt 37 and the guide plate 34. On the path 
of the copy paper 32 along the guide plate 34 and between the roller 36a 
and 36b, a leading edge detection switch SP1 and a trailing edge detection 
switch SP2 properly spaced from each other are disposed. As the copy paper 
32 is fed through the guide plate 34 and the roller pairs 33, 36a, and 36c 
toward the transfer station provided with the corona charger 41, the copy 
paper 32 is cut to a predetermined size by the cutter means K having a 
rotatory blade 35b and a stationary blade 35a. 
Referring also to FIG. 4, there is shown a manual copy paper sheet 
insertion and feeding mechanism provided above the copy paper roll 32, in 
which mechanism, a manual insertion cover plate 39 mentioned in greater 
detail later is pivotally disposed at an insertion opening 38 which is 
formed close to one end of the guide plate 34 adjacent to a pair of 
rollers 40a and 40b. The cover plate 39 normally located in a position 
shown by the solid line and closing the insertion opening 38 is rotated 
counterclockwise in the direction of the arrow T into a position shown by 
the dashed line so as to serve as a copy paper insertion plate for manual 
insertion of the copy paper sheet, whereby manual insertion cover switches 
SU5a, SU5b, SU5c and SU5d disposed in suitable positions are actuated, 
with the insertion opening 38 opened. The copy paper sheet inserted 
through the opening 38 is transported along the guide plate 34 in the 
direction of the arrow "f" as the rollers 40a and 40b rotate. On opposite 
sides of the pair of rollers 40a and 40b, there are disposed, along the 
guide plate 34, a manual insertion detection switch SP3 and temporary 
suspension switches SP4a and SP4b which are actuated upon passage of the 
copy paper sheet. 
For the switch-over between the manual copy paper insertion and the 
automatic copy paper feed from the paper roll 32, there is further 
provided, in the copying apparatus of the invention, a copy paper feed 
switch-over mechanism as described hereinbelow. The feed switch-over 
mechanism is of a simple construction in which the output portion of a 
clutch mechanism operated by one solenoid is selectively connected to the 
roll paper feeding rollers or the copy paper sheet feeding rollers. 
Referring to FIGS. 5 to 7 showing detailed construction of the copy paper 
feed switch-over mechanism, a sprocket 113 is rotatably mounted on a 
clutch shaft 115 through a bearing 114, while the clutch shaft 115 is 
rotatably supported by supporting frames 116a and 116b through bearings 
117a and 117b. A sprocket 118 secured to the driving shaft 36c of the 
roller 36a is connected to the sprocket 113 through a chain 119 (FIG. 6). 
Upon transmission of rotational force to the driving shaft 36c from a 
driving source (not shown), the transportation rollers 36a and the 
sprocket 113 are rotated. Further secured to the clutch shaft 115 are a 
clutch drum 120 and a clutch gear 121. On the outer periphery of the 
clutch drum 120, a sleeve 123 is rotatably mounted through a bearing 122, 
while a clutch spring 124 is spirally wound in the same direction as that 
of the rotation of the sprocket 113, with one end of the spring 124 being 
fixed to a boss portion of the sprocket 113 and with the other end of the 
spring 124 secured to an end face of the sleeve 123. A solenoid 125 is 
fixed to the supporting frames 116a and 116b through brackets (not shown), 
and a projection 128 secured to the outer periphery of a brake ring 127 
which is rotatably mounted on the sleeve 123 is connected to the end of a 
plunger 126 of the solenoid 125. The gear mounting plate 129, rotatably 
mounted on the boss portion of the clutch gear 121 and a pivotal portion 
116c of the supporting frame 116b, has an arm portion 129a extending 
sidewise therefrom. The arm portion 129a has supporting shafts 130a and 
130b secured thereto, on which idle gears 132a and 132b are rotatably 
mounted through bearings 131a and 131b. The gears 132 a and 132b mesh with 
each other, while the gear 132a also engages the clutch gear 121. The gear 
mounting plate 129 is rotatable about the clutch shaft 115 within the 
range in which its arm portion 129c extending upwardly contacts either a 
stopper 133a or a stopper 133b (FIG. 6). On the locus of upward and 
downward movement of the gear 132b, a gear 134 fixed to the same shaft as 
the roll copy paper feeding roller 33a and a gear 135 fixed to the same 
shaft as the copy paper sheet feeding roller 40a are disposed. The gear 
132b selectively engages the gears 134 or 135, following the movement of 
the gear mounting plate 129 in a manner as described below. Meanwhile, the 
stoppers 133a and 133b are so arranged as to restrict the movement of the 
mounting plate 129 within such a range that when the gear 132b engages the 
gears 134 and 135, they correctly engage, with their pitch circles being 
tangent to each other. 
On the other hand, the manual insertion cover plate or copy paper insertion 
plate 39 is fixed to a shaft 39a pivoted to the supporting frame 116b 
together with a switch-over plate 138, and can be rotated between the 
raised position and the lower position about the shaft 39a. In the raised 
position, the plate 39 closes the copy paper insertion opening 38 (FIG. 
1), while the plate 39 forms a copy paper sheet insertion mount together 
with the surface Ga (FIG. 1) of the apparatus housing G in the lowered 
position. 
Meanwhile, on the shaft 130b of the gear 132b, a gear engaging plate 139 is 
rotatably mounted. One end of a spring 140 is wound around the boss 
portion of the plate 139 and connected to a pin 141 fixed to one side of 
the plate 139 itself. The other end of the spring 140 is connected to a 
projection 129b provided at the end of the arm portion 129a of the gear 
mounting plate 129 mentioned earlier. The gear engaging plate 139 is 
normally urged counterclockwise about the shaft 130b by the restoring 
force of a spring 142 and is restricted from further rotation by contact 
of the side portion thereof with the projection 129b. Moreover, the shaft 
130b is normally urged downward (FIGS. 6 and 7) by the contact thereof 
with a central portion of a depressing spring 140, which is connected at 
one end 140a thereof to the apparatus housing, with the other end 140b of 
the spring 140 extending under the lower portion of the switch-over plate 
138. A lock plate 143 is pivotally disposed by a pin 144 secured to the 
supporting frame 116a, and a projection 143a formed at one end of the 
plate 143 engages a pin 126a provided at the outer periphery of the 
plunger 126 of the solenoid 125. The other end 143b of the plate 143 is 
located under the switch-over plate 138. Thus the plate 143 is rotatable 
about the pin 144, following the movement of the plunger 126 by the 
turning on or off of the solenoid 125. 
By the above arrangement, when the copy paper is to be fed from the paper 
roll 32 of FIG. 1 (FIG. 6), the manual insertion cover plate 39 is 
manually rotated to the raised position, with the switch-over plate 138 
being simultaneously rotated clockwise for depressing the end 140b of the 
depression spring 140 by the side piece 138a of the plate 138. 
Accordingly, the gear mounting plate 129 engaging the spring 140 through 
the shaft 130b rotates counterclockwise to a certain extent about the 
clutch shaft 115 until the arm portion 129c thereof contacts the stopper 
133a, with the gear 132b being engaged with the gear 134. Upon turning on 
of a print switch (not shown), copying operations such as charging, 
exposure, etc., are started, while the driving source (not shown) is 
energized to rotate the rollers 36a (FIG. 1), and the sprocket 118 whose 
rotation is transmitted to the sprocket 113 through the chain 119. The 
rotation of the sprocket 113 is transmitted to the sleeve 123 through the 
clutch spring 124 for idle rotation of the sleeve 123. In this state, when 
the copy paper feeding signal is given the solenoid 125 is energized, the 
plunger 126 of the solenoid 125 is retracted and an inner surface 127a of 
a brake ring 127 contacts, under pressure, the outer periphery of the 
sleeve 123 for braking the rotation of the sleeve 123, while the lock 
plate 143 engaging the pin 126a of the plunger 126 is rotated clockwise to 
a certain extent about the pin 144, with the end 143b of the plate 143 
entering the locus of rotation of the side piece 138a of the switch-over 
plate 138 for preventing the switch-over plate 138 and consequently the 
cover plate 39 from being rotated to the lowered position (locking). As 
the sprocket 113 continues to rotate despite the braking of the sleeve 123 
by the brake ring 127, the clutch spring 124 is pressed against the outer 
periphery of the clutch drum 120 for transmitting the rotational force to 
the clutch drum 120, and finally the sleeve 123 rotates with the clutch 
drum 120 through the clutch spring 124. The rotation of the clutch drum 
120 is transmitted to the clutch gear 121 through the clutch shaft 115 and 
further to the gear 134 via the gears 132a and 132b for rotating the roll 
paper feeding rollers 33a and 33b (FIG. 1) to feed the copy paper from the 
roll 32. Upon completion of the copy paper feeding, the solenoid 125 is 
turned off by a completion signal, and the plunger 126 is advanced for 
releasing the brake ring 127 from the sleeve 123, while the lock plate 143 
rotates counterclockwise by its weight, and the switch-over plate 138 is 
released from locking by the end 143b of the plate 143. 
On the other hand, when the copy paper sheet is to be fed through manual 
insertion (FIG. 7), the cover plate 39 in the raised position is rotated 
to the lowered position, by which rotation, the switch-over plate 138 is 
rotated counterclockwise. The spring 140 is released from the depression 
by the side piece 138a of the plate 138. The side piece 138b contacts the 
under side of the gear engaging plate 139 for rotating the plate 139 
clockwise to a certain extent about the shaft 130b. Following the rotation 
of the plate 139, the gear mounting plate 129 is rotated clockwise to a 
certain extent about the clutch shaft 115 until the arm portion 129c 
thereof contacts the stopper 133b by the spring force of the spring 142, 
and thus the gear 132b engages the gear 135. Thereafter, when the print 
switch (not shown) is turned on, the rotation of the sprocket 118 is 
transmitted from the gear 132b to the gear 135 for rotating the copy paper 
sheet feeding rollers 40a and 40b to feed the copy paper in the sheet 
form. 
Referring back to FIG. 1, the transfer charger 41 disposed at the transfer 
and charging station below the photoreceptor drum 2 and extending the 
axial direction of the drum 2 has a construction similar to that of the 
corona charger 70 mentioned earlier, with a negative high voltage being 
impressed to a wire electrode 41a enclosed therein, the negative high 
voltage of the wire electrode 41a causes the toner particles adhering to 
the photoreceptor surface 4 of the photoreceptor drum 2 to be sequentially 
attracted onto the copy paper sheet transported under the drum 2. The copy 
paper sheet onto which the toner particles are thus transferred is 
subsequently separated from the photoreceptor surface 4 as the separating 
claw 42 disposed adjacent to the drum 2 is pivoted clockwise into a 
position shown by the dashed line and placed on a transportation belt 43 
supported by transportation rollers 43a and 43b to move in the same 
direction as that of the belt 37 earlier mentioned. The transportation 
belt 43 has a plurality of suction openings (not shown) uniformly formed 
in its entire surface, through which openings, suction force caused by a 
fan motor M4 which is disposed below the belt 43 is exerted on the copy 
paper sheet for transporting the copy paper sheet attracted onto the 
surface of the belt 43 in a direction of the arrow "e" as the belt 43 
moves. In a suitable position adjacent to the belt 43, there is disposed a 
sheet separation detection switch SP5 for detecting the presence of the 
copy paper sheet after the separation. 
At the right hand side of the transportation belt 43 in FIG. 1, there are 
rotatably disposed a pair of fixing rollers 44a and 44b, each of which has 
a metallic core covered with a layer of silicone rubber or the like to 
form the surface, and is provided therein with a heating element H1 or H2 
to maintain its surface at a predetermined temperature. When the copy 
paper sheet having the toner particles adhering thereto passes between the 
fixing rollers 44a and 44b, the toner particles are fused onto the copy 
paper sheet by the heat of the rollers 44a and 44b. The copy paper sheet 
having the toner particles thus fused thereonto is discharged out of the 
apparatus housing G through another pair of discharge rollers 45a and 45b 
rotatably disposed subsequent to the fixing rollers 44a and 44b, while 
being detected by the discharge detection switch SP6 provided adjacent to 
the rollers 45a and 45b. 
Additionally, in the above described transfer and charging device wherein 
the toner image formed on the photoreceptor is transferred onto the copy 
paper sheet while the corona charge is applied to the copy paper sheet 
from the reverse side thereof by the transfer and charging device 41, a 
special method is employed as described hereinbelow for controlling the 
function of said transfer and charging device for eliminating the 
disadvantages inherent in the conventional transfer and charging devices, 
in which various problems are involved in the copy paper separation due to 
strong electrostatic attraction of the entire copy paper sheet onto the 
photoreceptor surface, because of the arrangement that the transfer and 
charging device is actuated before the arrival of the copy paper sheet at 
the transfer position for uniformly imparting charge onto the entire copy 
paper sheet. 
Still referring to FIG. 1, the microswitch SP1 disposed along the passage 
of the copy paper between the rollers 36a and 36b is adapted to cause a 
copying operation control cam plate (not shown) to rotate upon being 
turned on by the leading edge of the copy paper, while the transfer corona 
charger 41 which applies charge to the copy paper from the reverse side 
thereof is connected to a high voltage source (not shown) by signals 
produced through rotation of said cam plate (not shown). The separating 
claw 42 is also selectively brought into engagement with and spaced from 
the photoreceptor 4 by the rotation of said cam plate (not shown) and is 
controlled to contact the photoreceptor surface 4 only during separation 
of the copy paper therefrom. Upon initiation of the copying operation, the 
copy paper is transported in a manner described earlier in the direction 
shown by the arrow "e" and turns on the microswitch SP1 at its leading 
edge to cause the rotation of the copying operation control cam mentioned 
above. In synchronization with the arrival of the leading edge of the copy 
paper at a position immediately above the wire electrode 41a of the 
transfer charger 41 under the photoreceptor drum 2 in FIG. 1, the transfer 
charger operation starting signal is emitted through the rotation of the 
cam plate (a switch SC2 mentioned later is turned on), with the transfer 
charger 41 being actuated by connection to the high voltage source (not 
shown). Therefore, as compared with the conventional arrangements wherein 
the transfer and charging device is actuated prior to the arrival of the 
copy paper at the transfer position for uniformly charging the entire copy 
paper, the operation control method of the transfer and charging device of 
this invention, in which the transfer and charging device is actuated at 
the point as described above, the charging action of the transfer charger 
41 at the leading edge of the copy paper is extremely weak in comparison 
with the portion of the copy paper after its leading edge, thus 
electrostatic attraction of the copy paper toward the photoreceptor 
surface 4 at the leading edge thereof is sufficiently reduced, and the 
toner image on the photoreceptor surface 4 is hardly transferred onto the 
copy paper at said leading edge portion. In synchronization with the 
arrival of the leading edge of the copy paper at the copy paper separating 
station while the copy paper is being transported, with said leading edge 
lying on the photoreceptor surface 4, a separating claw actuation signal 
is transmitted through rotation of the above mentioned cam plate for 
pressing the tip of the claw 42 against the photoreceptor surface 4, and 
the leading edge of the copy paper is separated from the photoreceptor 
surface 4 by the claw 42. The copy paper thus separated from the drum 2 is 
attracted onto the suction belt 43 to be transported toward the subsequent 
processing device. It should be noted here that in the above described 
separation, since the leading edge of the copy paper is attracted onto the 
photoreceptor surface 4 with extremely weak electrostatic attraction as 
mentioned above, the copy paper sheet may be arranged to be separated from 
the drum 2 by the radius of curvature of the drum 2 and suction force of 
the belt 43 only, in which case the separating claw 42 may be dispensed 
with. After the trailing edge of the copy paper sheet has passed the 
transfer charger 41, a transfer charger operation stopping signal is 
emitted through said cam plate for disconnecting the transfer charger 41 
from the high voltage source (not shown). It is also to be noted that in 
the foregoing embodiment, the operation control for the transfer charger 
41 described as effected by the connection and disconnection of the 
charger 41 with respect to the high voltage source may be modified to be 
effected, for example, by providing a shutter plate member (not shown) 
disposed at the opening 41b (FIG. 1) of the transfer charger 41 and 
suitably associated with a solenoid (not shown) for sliding movement 
thereof for adjusting the width of the opening 41b. Additionally, although 
the transfer and charging device is mainly described with reference to the 
transfer charger 41, such transfer and charging device is not limited to 
the transfer charger 41, but other types of transfer and charging devices, 
for example, one of the types wherein an electrode roller (not shown) 
impressing charge onto the copy paper sheet from the reverse side thereof 
while pressing the copy paper sheet against the photoreceptor surface 4 
may be employed. 
Still referring to FIG. 1, above the separating claw 42, there are disposed 
a residual charge erasing device having a first eraser lamp 46 a charge 
erasing charger 47, and a cleaning device 48, while a second erasing lamp 
49 is disposed between the cleaning device 48 and the corona charger 70 
for removing the triboelectrical charge caused by a cleaner brush 50 of 
the cleaning device 48. An A.C. voltage is impressed to a wire electrode 
47a of the charge erasing charger 47 for erasing negative charge which can 
not be fully erased by the first eraser lamp 46 so as to remove electrical 
attraction between the toner particles and the photoreceptor surface 4. 
The cleaning device 48 comprises the brush 50 having brush bristles, for 
example, of rabbit hair and rotated at high speed in a direction shown by 
the arrow "g", and a filter bag 51 which includes a filter 51a having 
numerous openings (not shown) each smaller in diameter than that of the 
toner particles and a cleaner motor M5 disposed in the filter bag 51 for 
drawing in the air in the direction of the arrow " h". 
Referring now to FIG. 8, there is shown a modification of the residual 
charge erasing device illustrated in FIG. 1 described above. This 
modification is aimed at reducing the size of the residual charge erasing 
device and consequently the room occupied by the device in the copying 
apparatus through simple construction. The first eraser lamp 46 and the 
charge erasing charger 47 described as employed in the residual charge 
erasing device of FIG. 1 are replaced by a charge eraser 47A including a 
housing or lamp cover h, an erasing lamp l housed in the housing h, a dust 
preventing filter plate f of light transmitting and electrically 
insulating material such as acrylic resin which is mounted on an opening 
of the housing h facing the photoreceptor surface 4, and an A.C. corona 
charge generating charge wire w accommodated, for example, in a groove d 
formed in the central portion of the filter plate f. Although the charge 
wire 47a of the charge erasing charger 47 of FIG. 1 is surrounded by a 
stabilizing plate (not shown), such stabilizing plate is not necessarily 
required in the case of an A.C. corona discharge, and it has been 
experimentally confirmed by the present inventors that the construction of 
the above described modification is sufficient to fully erase the residual 
charge. 
Referring also to FIG. 9, a driving system for the copying apparatus of 
FIG. 1 is described hereinbelow. 
Upon rotation of a gear 52 by a main motor M1, a gear 53 fixed to a shaft 
of a copy paper feeding clutch CL1, a gear 54 secured to a shaft of a scan 
clutch CL2, a gear 55 fixed to a shaft of a return clutch CL3, a gear 5 
secured to the shaft 3 of the photoreceptor drum 2 (gear 7 etc, for a 
transmission mechanism abbreviated for brevity), a gear 56 fixed to a 
shaft of the transportation roller 36c, and a gear 57 secured to a shaft 
of the transportation roller 43b are rotated through a chain directed 
therearound. The rotation of the gear 53 is transmitted to a gear 58 fixed 
to a shaft of the feeding roller 33b through a gear 59 fixed to a shaft of 
the fixing roller 44b when the feeding clutch CL1 is energized, while in 
the manual insertion of the copy paper sheet, the rotation of the gear 53 
is transmitted through a gear 59 to a gear 60 secured to the shaft of the 
roller 40b. Meanwhile, when the scan clutch CL2 is energized, the rotation 
of the gear 53 is transmitted to a rack (not shown) secured to the 
platform 19 to drive the platform 19 in the direction of the arrow "b" of 
FIG. 1. When the return clutch CL3 is energized, the rotation of the gear 
55 is transmitted to the rack of the platform 19 to drive the platform 19 
in the direction opposite to the above direction. 
A chain is directed over the gear 57 secured to the transporting roller 43b 
and a gear 61 secured to the shaft of the discharging roller 45b for 
transmitting rotation. 
The rotation of the gear 7 for driving the drum shaft 3 is transmitted to 
the gear 10 (FIGS. 2 and 3) and the control cam driving gear 8 (FIGS. 2 
and 3) is rotated in a rotation period slightly shorter than the rotation 
period of the photoreceptor drum 2, the rate of which is determined by the 
difference in the number of teeth of the gears. 
The rotation of the gear 62 secured to a rotary shaft of a developing motor 
M2 is transmitted to a gear 64 which in turn rotates a gear 63 secured to 
a shaft of the outer cylinder 30a, a roller for supplying toner (not 
shown), the roller 28a for diffusing developing material, and the impeller 
28b for stirring developing material (FIG. 1). 
A shaft of a cooling motor M3 is secured directly to a cooling fan 20 (FIG. 
1) for rotating the latter, while the rotation of a gear 64 provided on 
the cleaner motor M3 is transmitted, through a belt 15, to a gear 66 for 
the brush 50. 
FIG. 10 shows a control circuit for controlling each mechanism of the 
copying apparatus of FIG. 1. The control circuit is composed of a power 
source circuit 80, a temperature regulating circuit 81 for controlling to 
a predetermined temperature the heaters H1 and H2 which heat the fixing 
rollers 44a and 44b, a power failure protection circuit 82 for effecting 
copying operation successfully after the power failure, an auto-shutter 
circuit 83 for controlling power supply only during the copying operation, 
a manual copy paper insertion driving circuit 84 for effecting copying 
onto copy paper sheet, and a jam detecting circuit 85 for detecting paper 
cloggings caused during copying process. 
Referring also to FIG. 11, the operation of the copying apparatus having 
the circuit construction as described above will be described hereinbelow. 
First, the original 23 of a desired size is placed on the glass face 22 of 
the platform 19. When power switches SU1 and SU1' are turned on (FIG. 
11(a)), current is caused to flow in the control circuit (shown in the 
lower portion of FIG. 10) through a transformer 88 (having a primary 
winding 88a and a secondary winding 88b), and a relay 8 is turned on to 
close contacts 8a1 and 8a2 for self-retaining so that the power is 
supplied to the entire circuit. Thus, heating voltage (FIG. 11, (r) and 
(e1)) is applied directly to the upper heater H1 from a control circuit 86 
of the temperature regulating circuit 81. A firing pulse is applied to a 
triac 87 which effects the phase control of the heating voltage of the 
lower heater H2 to heat the heaters H1 and H2 to a predetermined 
temperature. Meanwhile, the low voltage on the secondary winding 88b 
causes a power supply indication lamp 91 and a stand-by indication lamp 92 
to be lit through a full-wave rectifier 89 and a smoothing capacitor 90 
respectively. 
When the temperature of the heater H1 goes over a predetermined 
temperature, a relay R1 is actuated to open a normally-closed contact 1b 
so as to turn off the wait lamp 92 and to close a normally-opened contact 
1a. 
Under the above condition, a multi-dial (not shown) provided in a suitable 
location of the copying apparatus 1 may be operated to set (FIG. 11(k)) 
the dial so that "2" may be indicated, for example, to effect two sheet 
copying continuously. Thus, a multi-dial switch SU2 is switched from a 
contact "b" to a contact "a", which a switch SU2' is closed and a 
capacitor 94 which was charged through a resistor 93 is kept charged 
through resistor 95. 
In the above case, the platform 19 is located in a predetermined position. 
Switches SE1, SE1', SE1", SE1"' for detecting the positions of the 
platform 19 are set as shown. Meanwhile, the control cam 9 is also located 
in a predetermined position, with the switches SE1', SE1"' and SC1 being 
in closed positions respectively as shown. 
Upon turning-on of print switches SU3 and SU3' (FIG.11(b)), the switch SU3 
closed causes the power to be applied to the base of a transistor 96 
through the resistor 93 and the switch SU3. The transistor 96 is thus 
turned on to excite a relay R3 with a normally-open contact 3a1 thereof 
being closed to self-retain the relay R3 through transistor 96 (FIG. 
11(s). Through the excitation of the relay R3, the normally-open contact 
3a2 is closed to supply the power to subsequent stages of the circuit. On 
the other hand the normally-open contacts 3a3 and 3a4 are closed to 
operate the main driving motor M1, the cooling motor M3, the eraser lamps 
47 and 50, and an erasing charger driving transformer 97, to accelerate 
the rotation of the suction motor M4 and the cleaner motor M5 (FIG. 11(w)) 
with, and with to supply power to the full-wave rectifier 92 for driving 
the clutch mechanism. Closure of the switch SU3' excites the relay R2 to 
close the normally-open contact 2a1 for self-retaining the relay R2 (FIG. 
11(t)). Upon operation of the main driving motor M1, the photoreceptor 
drum 2 and the drum cam 6 start rotation. First, the drum cam 6 closes 
(FIG. 11(c)) a first drum signal switch SD1 to feed control to the set 
coil R4-S of a latching relay R4 through the normally-closed contact 5b1 
of the relay R5, a second drum signal switch SD2 and the contact 2a1 of 
the relay R2 which is closed already, and the set coil R4-S of the 
latching relay R4 is excited to set the latching relay R4 (FIG. 11(u)) and 
to close its normally-open contact 4a1. Upon closure of the normally-open 
contact 4a1, the clutch CL1 is energized through the manual paper-feeding 
cover switch SU5b and a random cut switch SE2, with the paper feeding 
rollers 33a and 33b being driven (FIG. 11, (p) and (z)) to transport the 
leading edge 32a of the copy paper from the roll 32 in the direction of 
the arrow "e" (FIG. 1) along the guide plate 34 for transportation. Thus, 
the switches SP1 and SP2 for detecting the leading edge are switched on 
respectively (FIG. 11, (f) and (g)), and the high voltage power source HT1 
of the charger 70 is energized (FIG. 11, (g1)) to uniformly apply, onto 
the photoreceptor surface 4 of the photoreceptor drum 2, a negative 
electric charge produced in the wire electrode 70a of the charger 70, 
while the relay R5 is excited (FIG. 11(v)) for switching over a contact 
5T1 and a contact 5T2. Through the switching-over of the contact 5T1, a 
platform lock solenoid SL1, the control cam lock solenoid 14 and the scan 
clutch CL2 are energized respectively (FIG. 11, (a1), (b1)), while through 
the switching-over of the contact 5T2, the exposure lamp 21 is energized 
(FIG. 11(d1)), with heating of the lower heater H2 (FIG. 11(f1)) being 
suspended. 
Upon energization of the scan clutch CL2, the platform 19 is moved in the 
direction of an arrow "b", and the platform positioning switch SE1 is 
switched-over (FIG. 11(m)), with the platform lock solenoid SL1 and the 
control cam lock solenoid 14 de-energized, while the switches SE1' and 
SE1"' are opened, thus the operating sequence becomes independent, even if 
the print switch SU3' is turned on. When the platform 19 advancing in the 
direction of an arrow "b" reaches a position corresponding to the length 
of the original 23, the random cut switch SE2 is turned on to be switched 
over to a position opposite to that in FIG. 10 for energizing (FIG. 11(y)) 
the cutter solenoid SL2 so as to drive the cutters 35a and 35b (FIG. 
11(n)), thereby to cut the copy paper 32 to a length corresponding to the 
original 23. At the same time, a cutter on-switch SS1 is turned on (FIG. 
11(o)) to energize the reset coil R4-R of the latching relay R4 so as to 
open the normally-open contact 4a1 from its closed position again, with 
the energization of the cutter solenoid SL2 being suspended to complete 
the paper-feeding and paper-cutting operations. 
As the trailing edge of the cut copy paper sheet 32 passes the leading edge 
detection switch SP1, the switch SP1 is opened from its closed state to 
suspend current flowing to the high voltage power source HT1, thereby to 
suspend application of the negative electric charge onto the photoreceptor 
drum 2 from the corona charger 70. As the copy paper 32 further advances 
in the direction of the arrow "e" so its trailing edge passes the trailing 
edge detection switch SP2, the switch SP2 is also opened from its closed 
state to de-energize the relay R5, thus restoring the contact 5T1 and the 
contact 5T2 to the condition as shown in FIG. 10. Thus, the scan clutch 
CL2 is de-energized and, at the same time, the platform position detection 
switch SE1 is switched over to the contact opposite to that shown in FIG. 
10. Accordingly, the current flows to the return clutch CL3 (FIG. 11(c1)) 
and the platform 19 is transported in a direction opposite to that of the 
arrow "b". Also, through the switching over of the contact 5T2, the 
exposure lamp 21 is turned off, and the lower heater H2 is turned on. 
On the other hand, the drum shaft 3 is rotated in synchronization with the 
movement of the platform 19 in the direction of the arrow "b". The 
photoreceptor drum 2 and the drum cam 6 rotate in the direction of the 
arrow "a", while the control cam 9 is rotated in the direction of the 
arrow "a" through the control cam driving gear 8, in a period slightly 
shorter than the rotating period of the drum cam 6, when the control cam 
lock solenoid 14 is excited. Thus, the cam regular position switch SC1 is 
switched over (FIG. 11(i)). Meanwhile, the light rays from the exposure 
lamp 21 directed to a predetermined position of the platform 19 are 
applied sequentially onto the original 23 through the glass face 22 as the 
platform 19 advances in the direction of the arrow "b" of the platform 19. 
The light rays reflected therefrom are sequentially projected onto the 
photoreceptor surface 4 of the photoreceptor drum 2 through the mirror 24, 
the mirror lens 25, and the mirrors 26 and 27. Accordingly, the 
photoreceptor 4 rotates, forming electrostatic latent images corresponding 
to contents of the original 23, with the negative charge being removed 
where the density of the original 23 is low, and with the negative charge 
remaining where the density thereof is high. 
As the photoreceptor 4 rotates, the control cam 9 is also rotated in the 
direction of the arrow "a" independently, and a switch operating plate 9b 
of the control cam 9 (FIGS. 2 and 3) comes into contact with the operating 
lever 17. Accordingly the operating lever 17 rotates counterclockwise 
against the force of the spring (not shown) to engage into a stepped 
portion 18b of a supporting lever 18, and is held in the position 
illustrated by the solid lines of FIG. 3 to turn on a developing switch 
SK1. When the developing switch SK1 is turned on (FIG. 11(q)), the 
developing motor M2 is driven (FIG. 11(x)) to rotate the outer cylinder 
30a, toner supplying roller (not shown), developing material diffusing 
roller 28a and developing material stirring impeller 28b. Thus, the toner 
which is stored in the toner tank 29 is charged to a positive polarity by 
the carrier of the developing material, and is attracted sequentially, 
through the outer cylinder 30a, onto the portion of the photoreceptor 
surface 4 which has been charged to a negative polarity to manifest the 
static latent images. 
When the image which has been manifested through adherence of the toner 
confronts the transfer charger 41, and the sheet 32 is fed along the guide 
plate 34, the transfer switch SC2 is closed (FIG. 11(j)) by the control 
cam 9 and the transfer charger 41 is energized (FIG. 11(h1 )) for 
sequentially attracting the toner particles on the photoreceptor surface 4 
onto the copy paper sheet 32. When the transfer switch SC2 is closed, the 
relay R6 is excited to close the contact 6a1 and the contact 6a2 so as to 
self-retain the relay R6. 
During the above period, the pin 6a of the drum cam 6 comes into contact 
with the other end of the supporting lever 18 through rotation of the cam 
6, and the operating lever 17 returns to its original position shown in 
the dashed line in FIG. 3 to turn off the latch switch SK1, and to stop 
the developing motor M2 to complete the developing operation. Immediately 
after this, namely, after the toner has been attracted onto the sheet 32, 
a transfer offswitch SD3 is switched over by the drum cam 6, which opens 
the switch SD3 and denergizes the transfer charger 41. 
The copy paper sheet 32 is separated from the photoreceptor surface 4 by 
the separating claw 42 and is transported by adherence to the surface of 
the transporting belt 43. The switch SP5 for detecting the sheet 
separation is switched over, with the contact opened. Thus, even if a 
switch SD4 for detecting unsuccessful separation is turned on by the drum 
cam 6 immediately after this to close the contact, a latching relay R7 is 
not energized and is set. As the copy paper sheet 32 is further 
transported, the toner is fused onto the sheet 32 by fixing rollers 44a 
and 44b, and thus the sheet 32 is discharged out of the apparatus 1 
through the discharging rollers 45a and 45b to turn on the discharge 
detection switch SP6 (FIG. 11(h)). Thus, the discharge detection switch 
SP6 is switched over from a contact "a" to a contact "b" to discharge the 
electric charge which is charged in a capacitor 94, through a jam 
detecting switch SD5 and a resistor 98. After the sheet 32 has passed the 
discharge detection switch SP6, the switch SP6 is turned off again for 
switching over the contact from "b" to "a". In this case, the multi-dial 
switch SU2 is switched over to a contact "a", and the capacitor 94 is 
charged through a resistor 95. In this manner, the copying operation for a 
first sheet 32 is completed. 
During the copying operation of the first sheet, when the platform 19 is 
transported in the opposite direction shown by the arrow "b" and is 
returned to its original position, the multi-dial is counted down by one 
to close the multi-start switch SE3 (FIG. 11(l)). In this case, the relay 
R2 is excited in a manner similar to the copying operation of the first 
sheet through a function (not shown) for retaining, in the above-described 
condition, namely, in the closed condition, the multi-dial switches SU2 
and SU2' provided between "2" and "1" of the display of the multi-dial. 
Since the contact 5b1 of the relay R5, the paperfeeding switch SS2, and a 
second drum signal switch SD2 are all kept closed, the relay R2 is 
self-retained by the contact 2a1. 
Subsequently the platform 19 is transported in the direction of the arrow 
"b" again after the copying operation of the first sheet, and a second 
copying operation is effected through operation similar to that described 
hereinabove. As the platform 19 is transported again in a direction 
opposite to that of the arrow "b", the multi-dial counts down to indicate 
"1" and the multi-dial switch SU2' opens, and thus even when the 
multi-start switch SE3 closes through the returning of the platform 19 to 
its original position, the relay 2 remains de-energized. Similarly, upon 
the counting-down of the multi-dial, the multi-dial switch SU2 is switched 
over from a contact "a" to contact "b", while the contact 2T1 of the relay 
R2 is also closed the "b" side, and the terminal voltage of the capacitor 
94 becomes the base-emitter voltage of the transistor 96. 
An automatic shutting off arrangement of the copying apparatus will be 
described hereinbelow. 
When the copying operation of the second sheet is completed and the sheet 
32 is discharged out of the apparatus, and the discharge detecting switch 
SP6 is turned on, the contact is switched over from "a" to "b" so that the 
electric charge of the capacitor 94 is discharged through a resistor 98, 
and the terminal voltage of the capacitor 94 is reduced to zero. 
Accordingly, even when the switch SP6 is switched over from "b" to "a" 
again after the sheet 32 has passed, the base voltage of the transistor 96 
becomes zero momentarily. Thus the transistor 96 is turned off to 
de-energize the relay R3, and the contact 3a1 being opened to release the 
self-retaining of the relay R3. Accordingly, the contacts 3a3 and 3a4 of 
the relay R3 are opened and the current flowing through the main motor M1, 
the eraser lamps 47 and 50, and the charge erasing transformer 97 is 
suspended, while the power is still supplied to the cleaner motor M5 and 
the suction motor M4 through the resistor 99 for driving the same at 
reduced efficiency. Also, upon opening of the contacts 3a2 and 3a4 through 
the de-energization of the relay R3, the current flowing through each 
control circuit for the copying operation is also suspended automatically 
to stand by for the next copying operation. Accordingly, useless power 
consumption during the non-operating period of the apparatus 1 is 
maintained at a minimum level. In order to cut off the current flowing 
through the apparatus 1 completely, the main power supply off-switch SU4 
is opened to break the contact of the relay R8, and thus the 
self-retaining of the relay R8 is removed to suspend power supply. 
The copying operation by the manual copy paper feeding will be described 
hereinafter. 
In order to feed the manual insertion sheet into the apparatus 1, the cover 
plate 39 (FIG. 1) for manual feeding is rotated counterclockwise to the 
lowered position, thus the contact of the cover switch SU5a for manual 
feeding is closed, and the contact of each of the switches SU5b, SU5c and 
SU5d is switched over from the contact "a" to "b". In this case, the 
platform 19 is still located in the predetermined position and thus the 
contact of the switch SE1 for detecting the predetermined position of the 
platform 19 is in the position as shown, with the contact of a temporary 
stop switch SP4a being closed. Accordingly, the current flows through the 
paper feeding clutch CL1 by the closure of the contact of the manually fed 
cover switch SU5a. 
Upon insertion of the sheet for manual feeding into the opening 38 for the 
manual paper feeding (FIG. 1) the contact of the manual insertion 
detection switch SP3 is closed through the passing of the manual feeding 
sheet so as to turn on the transistor 96, and the relay R3 is excited to 
close the contact 3a1 so that it may be self-retaining while contacts 3a3 
and 3a4 are closed for supplying power to each control circuit in the rear 
stage. Thus, the main driving motor M1 is driven and the paper feeding 
rollers 40a and 40b rotate through the paper feeding clutch CL1 so that 
the manually fed sheet is drawn into the apparatus 1. The manually fed 
sheet, first, switches over the temporary stop switches SP4a and SP4b, and 
thus the contact of the SP4a is opened to suspend the current flowing 
through the paper feeding clutch CL1. Upon stopping of the manual feeding 
sheet at a predetermined position, the contact of the switch SP4b is 
switched over from "b" to "a", and the relay R2 is excited and at the same 
time, is self-retained through the contact 2a1 for standing by until the 
first drum signal switch SD1 is turned on, namely, the photoreceptor drum 
2 rotates up to a predetermined position. 
As the drum cam 6 rotates through the rotation of the photoreceptor drum 2 
and the first drum signal switch SD1 is turned on, with the contact 
thereof closed, the current flows through the setting coil R4-S of the 
latching relay R4, and the contact 4a1 thereof is closed to flow the 
current to the paper feeding clutch CL1 again. Thus, the manually fed 
sheet is transported along the guide plate 34, while the leading edge of 
the sheet passes the switch SP1 for detecting the leading edge and the 
switch SP2 for detecting the trailing edge to turn on the switches SP1 and 
SP2, thus the relay R5 is excited to switch over the contact 5T1, thereby 
to move the platform 19 and the control cam 9. If the random cut switch 
SE2 is switched over during the movement of the platform 19, the current 
continues to flow through the paper feeding clutch CL1, since the contact 
of the manual feeding cover switch SU5b is already switched to "b" side. 
Therefor, no current flows through the cutter solenoid SL2. 
As the manually fed sheet is further transported and the trailing edge of 
the manually fed sheet has passed the temporary stop switches SP4a and 
SP4b, both of the switches SP4a and SP4b are turned off and the contact of 
the switch SP4b is switched over to "b" side, causing current to flow 
through the resetting coil R4-R of the latching relay R4, and thus opening 
the contact 4a1. At this time, as the platform 19 starts to move, the 
platform positioning switch SE1 is switched over to a position opposite to 
that as shown in FIG. 10. Thus, no current flows through the paper feeding 
clutch CL1. And through the same operation as in the roll paper described 
earlier, the contents corresponding to the original are copied on the 
manually fed sheet with the sheet being subsequently discharged out of the 
apparatus. 
Hereinbelow, the copy paper jam detection arrangement employed in the 
copying apparatus of this invention will be described. 
If a paper jam takes places during the paper feeding portion of the copying 
operation, the leading edge of the sheet closes the switches SP1 and SP2 
for detecting the leading edge, and before the relay R5 is de-energized, 
the second drum signal switch SD2 is switched over through the rotation of 
the drum cam 6. At this time, if the paper feeding clutch CL1 has been 
actuated, and the paper feeding onswitch SS2 is opened, the switch SS2 and 
the switch SD2 stop the current flow through the relay R2, and thus, the 
relay R2 is de-energized. This current is caused to flow through the 
resetting coil R4-R of the latching relay R4, and the contact 4a1 thereof 
is opened to stop the current flowing through the paper feeding clutch 
CL1. Thus, the paper feeding operation is suspended. 
Should a paper jam take place due to unsuccessful separation in the sheet 
separating portion, the switch SD4 for detecting the unsuccessful 
separation is turned on through the rotation of the drum cam 6, and the 
normally closed switch SP5 for detecting separation is not opened, since 
the sheet has not passed the switch SP5. Accordingly, current flows to the 
setting coil R7-S of the latching relay 7 through the contact 6a1 already 
closed and the contact 7T1 is switched over from "a" to "b" to light a 
pilot lamp 100 for indicating the jam and to de-energizing the relay 8 so 
as to open the contacts 8a1 and 8a2. Thus, all the power supply to the 
apparatus 1 is cut off to stop operation of the apparatus 1. When the jam 
resetting switch SU6 is closed after the sheet which caused the paper 
jamming has been taken out, the resetting coil R7-R of the latching relay 
R7 is energized for switching over the contact 7T1 to the "a" side to 
again energize the relay R8. Thus, the contacts 8 a1 and 8a2 are closed to 
energize the control circuit in each rear stage for restoring the original 
condition. 
Additionally, if a paper jam takes place due to unsuccessful transportation 
of the sheet at the fixing station, the contact of the separation 
detecting switch SP6 remains closed to the "a" side, since the sheet does 
not pass therethrough, and since the jamming detection switch SD5 is 
turned on through the rotation of the drum cam 6, the contact thereof is 
switched over for applying the electric charge of the capacitor 94 to the 
setting coil R7-S of the latching relay R7 through the contact 6a1. 
Accordingly, similar to the above case, the contacts 8a1 and 8a2 of the 
relay R8 are opened respectively to stop the power supply to the apparatus 
1. The operation of the jam resetting switch SU6 is the same as in the 
above described case. 
Finally, the case in which the power supply to the apparatus is suspended 
due to accidents such as power failure during the copying operation will 
be described. 
Firstly, if the power failure takes place before or after the energization 
of the transfer charger 41 and the power supply switches SU1 and SU1' are 
turned on after restoration of the power failure, the current is again 
caused to flow through the transformer 88 and the full wave rectifier 89 
and also to the temperature regulating circuit 81, and thus the relay R1 
is excited to open the contact 1b and to close the contact 1a, while the 
relay R8 is excited to close the contacts 8a1 and 8a2 to self-retain the 
power supply circuit. Since the relay R3 remains de-energized the 
apparatus 1 is kept inoperative at a condition before the power supply was 
cut off. And upon closure of the print switch SU3, the transistor 96 is 
turned on, and the relay R3 is energized, and the contact 3a1 thereof is 
closed to self-retain the relay R3, while the contact 3a2 is closed to 
flow the current to each circuit in the rear stage. Also, the contacts 3a3 
and 3a4 are closed to flow the current through each of the motors M1, M2 . 
. . M5 and the circuit in the rear stage. Thus, the copying operation 
which is suspended is continued, and the sheet is discharged out of the 
apparatus 1. 
Furthermore, during the operation of the transfer charger 41, if the power 
supply is cut off as described hereinabove, and the print switch SU3 is 
closed after turning on the power switches SU1 and SU1' a similar 
operation to that described hereinabove is effected. In this case, since 
the contact of the transfer on-switch SC2 is opened after it is closed by 
pulse-like signal, once the relay R6 is de-energized due to interruption 
of the power supply, no current flows through the transfer transformer, 
i.e., through the transfer charger 41. Thus, the print switch SU3 excites 
the relay 3 to close the contact 3a3 thereof and to flow current through 
the suction motor M4, in which case, since the sheet is not 
electrostatically attracted onto the photoreceptor drum 2 even when the 
rising of the suction force of the suction fan is slow, the sheet is 
separated easily from the photoreceptor drum 2 for transportation, and is 
discharged out of the apparatus 1. 
FIG. 12 shows a modification of the power failure protection circuit of the 
apparatus 1. During the energization of the transfer charger 41, if the 
print switch SU3 is turned on to close the contact after restoration of 
the power failure, the transistor 96 is turned on to energize the relay R4 
and the contact 4a4 thereof is closed for energizing the circuit in the 
rear stage, while the contact 4a3 is also closed for self-retaining the 
relay R4 to restore the condition before the power failure. In this case, 
since the transfer-on switch SC2 is already opened after it is once closed 
in the pulse-like manner, a thyristor S remains off, namely, memorizes the 
occurrence of the power failure and the transfer transformer, i.e., the 
transfer charger 41 is not energized. Accordingly, as described 
hereinabove, the sheet is separated easily from the photoreceptor drum 2 
for being transported and is discharged out of the apparatus 1 without 
causing any paper jam. 
Referring also to FIGS. 13 and 14, one example of the circuit construction 
of the developing biasing voltage timing control means for charging only 
the latent image forming portion, without charging the non-image forming 
portion of the photoreceptor mentioned earlier is described hereinbelow. 
The static latent images formed on the photoreceptor surface 4 are 
developed by the magnetic brush developing apparatus 28 (FIG. 1). A 
variable bias applying means V as shown in FIG. 14 is coupled to the 
magnetic brush to be formed on the outer cylinder 30a. In the bias 
applying means V, an electric supply E (AC 100 V) is connected to the 
primary side of a developing bias transformer Td, to which a resistor R2 
is connected in parallel, through a normally-open contact of a switch SWD 
connected in parallel to a resistor R1 for voltage dropping, while a 
secondary side thereof which is connecetd in series to a diode Dr for 
rectification and in parallel to the resistor R3 and a smoothing capacitor 
C is connected to the outer cylinder 30a of the developing roller 30. The 
switch SWD is installed at a point C which is away from a transfer point A 
(the position of the transfer charger 41) on the passage for transporting 
the copy paper by an interval equivalent to AB (the distance from the 
developing point B to the transfer point A). Accordingly, as the transfer 
paper which is transported in association with the copying operation 
arrives at the point C to turn on the switch SWD, developing bias voltage 
of -300 to -400 V is applied onto the outer cylinder 30a of the magnetic 
roller 30. At this time, the front edge of the latent image formed portion 
on the photoreceptor surface 4 is located at the developing point B, and 
the latent images having the electric charge of -700 to -800 V on the 
image-formed portion are developed by the toner in the earlier described 
manner. On the other hand, background portion exposed through projection 
from the mirror 27 has the residual potential of -100 to -200 V, but no 
toner adheres due to the effect of the above described bias voltage, thus 
ensuring so-called fog-free developing operation. 
Application of -300 to -400 V bias voltage as described above is continued 
during the developing time period. In other words, since "on" state 
remains until the copy paper passes the switch SWD, and the "on" state is 
switched over to "off" state when the copy paper passes, the 100 V a.c. 
from the power source E is applied, through the resistor R1 for voltage 
dropping, to the primary side of the developing bias transformer Td. 
As the switch SWD is turned off, the output from the secondary side of the 
transformer Td becomes -100 to -200 V to apply the bias voltage onto the 
outer cylinder 30a. This condition continues till the next developing 
operation, namely, until the leading edge of a subsequent copy paper 
actuates the switch SWD to turn it on. Accordingly, although the magnetic 
brush formed on the outer cylinder 30a comes into sliding contact with the 
nonimage formed portion of the photoreceptor surface 4, the adhesion of 
the toner thereto is prevented due to the presence of bias voltage of -100 
to -200 V as described above. 
The toner powder image on the image-formed portion of the photoreceptor 
surface 4 is transferred onto the copy paper by the transfer charger 41 
and the copy paper sheet having the toner powder image thus transferred is 
transported to the fixing device for the fixing operation, while the toner 
remaining on the photoreceptor surface 4 is removed by the cleaning device 
48. 
It should be noted that the biasing voltage timing control means is not 
limited in its arrangement to the above described embodiment, but may be 
modified in various ways. For example, the position of the switch SWD may 
be spaced in distance more than AB from the transfer point A. Needless to 
say, the switching operation of the switch SWD has only to be effected 
through detection of the time when the magnetic brush formed on the outer 
cylinder 30a comes into contact with the leading edge of the image-formed 
portion and then leaves the trailing edge thereof, namely, through 
detection of the developing period. In the above embodiment, the switch 
SWD is arranged to be responsive to the transportation of the copy paper, 
because the actuation of the switch SWD is readily associated with the 
copying operation. 
Referring now to FIGS. 15 to 17, there is shown the detailed construction 
of the copy paper cutting means K employed in the copying apparatus of 
FIG. 1. The cutting means K includes an arrangement for preventing copy 
paper jamming at the cutting means K wherein a stationary blade 35a and a 
rotary blade 35b are employed. In FIG. 1, after the leading edge of the 
copy paper 32 is drawn from the paper roll through the feeding rollers 33a 
and 33b, and a predetermined amount of the copy paper has been fed through 
the space between the stationary blade 35a and the rotary blade 35b, the 
rotation of the rollers 33a and 33b is suspended by a cutting signal 
developed by suitable means (not shown) in the copying apparatus, and the 
rotary blade 35b is simultaneously rotated counterclockwise by suitable 
means such as a solenoid (not shown) in the direction shown by the solid 
line arrow in FIGS. 15 and 16 toward the stationary blade 35a for cutting 
the copy paper 32 therebetween. After completion of cutting, the rotary 
blade 35b is rotated clockwise as shown by the dashed line arrow in FIGS. 
15 and 16 back to the original position, and the copy paper sheet thus cut 
is further transported into the copying apparatus. In the above described 
arrangement, if the feeding rollers 33a and 33b are not maintained in a 
perfectly stationary state when the rotary blade 35b is rotated 
counterclockwise toward the stationary blade 35a for cutting the copy 
paper 32, the leading edge of the copy paper from the roll 32 thus cut by 
the cutter means K is slightly curved upwardly when the rotary blade 35b 
is to return to the original position and tends to ride over the rotary 
blade 35b to a certain extent. In the above state, after the rotary blade 
35b has returned to the original position, with the copy paper feeding 
through the rollers 33a and 33b being resumed, the leading edge of the 
copy paper thus curved goes further onto the rotary blade 35b and may give 
rise to a paper jam there. Such a problem is advantageously eliminated in 
the copying apparatus of this invention by an arrangement wherein the 
movement of the rotary blade or the actuation mechanism associated 
therewith is utilized for temporarily rotating the feeding rollers 33a and 
33b in the reverse direction in association with the movement of the 
cutter blade after cutting so as to cause the cut edge or leading edge of 
the copy paper to be retracted from the cutter blades. Thus cutter means 
provided with a paper jam prevention arrangement is embodied as described 
in more detail hereinbelow. 
In FIGS. 15 to 17, the cutter means K includes a stationary blade 35a and a 
rotary blade 35b. The rotary blade 35b is secured to one end of a rotary 
shaft 202 (FIG. 17) which is rotatably supported by a frame 203 of the 
copying apparatus, while a cutter arm plate 204 is fixedly mounted at a 
base portion thereof to the other end of the rotary shaft 202. The cutter 
arm plate 204 further has a cutter arm pin 204a secured to a forward end 
of the plate 204. The cutter arm pin 204a is slidably received in a 
corresponding opening of a cutter arm pin receiver 206a formed at one end 
of a cutter lever 206 which is connected at the other end thereof to a 
plunger of a solenoid (not shown). A spring 207 is connected between the 
end of the lever 206 adjacent to the cutter arm pin receiver 206a and the 
frame 203 of the copying apparatus for normally forcing the cutter lever 
206 upward as shown in FIGS. 15 and 16. 
On the other hand, a rotary shaft 208 for the upper roller 33a of the paper 
feeding rollers 33a and 33b is rotatably supported by the frame 203 of the 
apparatus housing G (FIG. 1). A driving gear 209, a friction clutch 
mechanism 210, a compression coil spring 211, a roller return plate 212 
and a torsion spring 213 (FIG. 17) are mounted on one end of the rotary 
shaft 208. The driving gear 209 and a friction plate 210a of the friction 
clutch mechanism 210 are engaged with a notch 208a of the shaft 208 so 
that they may be rotated as one unit with the shaft 208. Other friction 
plates 210b and 210c, the compression coil spring 211, the roller return 
plate 212 and the torsion spring 213 are movable independent of the shaft 
208. The torsion spring 213 is engaged, at its one end, with a projection 
212a of the roller return plate 212 and, at its other end, with a pin 214 
secured to the frame 203 for normally forcing the roller return plate 212 
to pivot clockwise. 
Meanwhile, a rocking lever 216 is pivotally supported by a support shaft 
215 secured to the frame 203 and is normally forced to pivot 
counterclockwise by a torsion spring 217. The front end portion 216a of 
the rocking lever 216 is so arranged that it may come into contact with 
the cutter arm pin receiver 206a of the cutter lever 206 when the cutter 
arm pin receiver 206a is moved downward through the action of the solenoid 
(not shown). The roller return plate 212 is provided with an upper notch 
212b, a lower notch 212c and a rotation regulating claw 212d. The lower 
notch 212c and the rotation regulating claw 212d are actuated in 
association with a bent portion 216b of the rocking lever 216 in a manner 
mentioned later. 
The operation of the above cutting means K will be described hereinafter. 
As a paper feeding signal is transmitted from the copying apparatus (not 
shown), the rotating force is transmitted from a driving source (not 
shown) through a proper means such as a clutch, etc. to operate the paper 
feeding rollers 33a and 33b. The friction plate 210a of the friction 
clutch mechanism 210 rotates integrally with the shaft 208, while the 
other friction plates 210b and 210c are pressed against the driving gear 
209 by the compression coil spring 211 to rotate therewith. Since the 
compressed coil spring 211 is engaged, at one end, with the friction plate 
210c, and, at its other end, with the upper notch 212b of the roller 
return plate 212, the roller return plate 212 also rotates, against the 
force of the torsion spring 213, through the rotation of the friction 
plates 210b and 210c. When the bent portion 216b of the rocking lever 216 
engages the lower notch 212c, the rotation of the plate 212 stops, so that 
the contact surfaces of the friction plates 210a and 210b slide against 
each other. 
The roller return plate 212, the rocking lever 216, the friction plates 
210b and 210c, etc. retain condition (the condition of FIG. 15) 
independently of the rotation of the shaft 208. When a predetermined 
amount of paper has been fed, a cutting signal is transmitted from the 
copying apparatus, and simultaneously with the stopping of the paper 
feeding rollers 33a and 33b, a solenoid (not shown) is actuated to pull 
the cutter lever 206 for rotating the rotary blade 35b counterclockwise, 
through the cutter arm 204 of the cutter means K, and thus the copy paper 
located between the stationary blade 35a and the rotary blade 35b is cut. 
Even after the cutting operation has been completed, the cutter lever 206 
continues to descend and the lower portion of the cutter arm pin receiver 
206a pushes down the front end portion 216a of the oscillating lever 216 
against the urging force of the torsion spring 217. Accordingly, the bent 
portion 216b and the lower notch 212c of the roller return plate 212 are 
disengaged from each other, and the roller return plate 212 pivots 
clockwise momentarily due to the force of the torsion spring 213. The 
rotation regulating claw 212d comes into contact with the bent portion 
216b of the rocking lever 216 for stopping the rotation of roller return 
plate 212 (the condition of FIG. 16). The input signal to the above 
mentioned solenoid is then immediately suspended, and the cutter lever 206 
is raised by the spring 207 to restore the rotary blade 35b of the cutter 
means K to its original position ready for subsequent cutting to stand by 
until the next cutting signal is applied thereto. 
At this time, as described hereinbefore, the roller return plate 212 pivots 
clockwise, with the rotation thereof being transmitted to the friction 
plate 210a, through the compression coil spring 211 and the friction 
plates 210c and 210b to rotate the rotary shaft 208 of the upper paper 
feeding roller 33a in the same direction. Thus, the paper held between the 
paper feeding rollers 33a and 33b is pulled back or retracted by a 
predetermined amount away from the cutter means K. 
When the paper feeding signal is again applied to start the subsequent 
paper feeding and the upper roller 33a of the paper feeding rollers 33a 
and 33b is rotated counterclockwise, the friction plates 210b and 210c are 
rotated in the same direction through the friction plate 210a, as 
described hereinabove, to transmit the rotation thereof to the roller 
return plate 212 through the compression coil spring 211. The bent portion 
216b on the rocking lever 216 which is urged counterclockwise by the 
torsion spring 217 engages the lower notch 212c of the roller return plate 
212 to stop the rotation thereof, and this condition remains until a 
subsequent cutting signal is applied. 
Referring now to FIGS. 18 to 20, there is shown a modification K' of the 
cutter means K of FIGS. 15 to 17. In this modification, the cutter arm 204 
is fixed to one end of the rotary shaft 202 of the rotary blade 35b in the 
similar manner as in the embodiment of FIGS. 15 to 17, while the cutter 
arm pin 204a provided on the end portion of the cutter arm 204 is 
rotatably coupled to the cutter arm pin receiver 206a of the cutter lever 
206 which is connected to the plunger of the solenoid (not shown). 
Furthermore, a pin 206b is fixedly provided on the cutter lever 206 at the 
side thereof opposite to its cutter arm pin receiver 206a. 
On the other hand, a roller return lever 218 and a friction plate 219 are 
rotatably provided on one end of the rotary shaft 208 of the upper roller 
33a of the paper feeding rollers 33a and 33b. A compression coil spring 
220 is engaged, at its one end, with the rotary shaft 208 and, at its 
other end, with the friction plate 219 for depressing the friction plate 
219 against the roller return lever 218. Also, a stopper 221 is fixedly 
provided on the frame 203 to restrict the rotation of the roller return 
lever 218. 
In this case, the roller return lever 218 rotates synchronously with the 
shaft 218 by the compression coil spring 220 and the friction plate 219 
with respect to the rotation of the paper feeding rollers in the paper 
feeding direction. When the roller return level 218 comes into contact 
with the stopper 221, slipping takes place in the contact faces between 
the roller return lever 218 and the friction plate 219, with the roller 
return lever 218 coming to a stop, independently of the rotation of the 
upper paper feeding rollers 33a. This condition is shown in FIG. 18. 
Subsequently the paper feeding rollers 33a and 33b are stopped by a 
cutting signal from the copying apparatus (not shown), and simultaneously, 
a solenoid (not shown) is actuated to pull the cutter lever 206 downwardly 
to pivot the rotary blade 202a counterclockwise to cut the copy paper. 
Even after the cutting operation, the cutter lever 206 continues to 
descend. At this time, since the pin 206b is so arranged as to contact the 
front end portion of the roller return lever 218, the roller return lever 
218 pivots clockwise about the shaft 208 through the descending of the pin 
206b. The shaft 208 also rotates in the same direction, through the 
friction plate 219 and the compression coil spring 220, by the clockwise 
pivotal motion of the roller return lever 218 to pull back the leading 
edge portion of the copy paper held between the paper feeding rollers 33a 
and 33b by a predetermined amount away from the cutter means K'. When the 
input signal to the above mentioned solenoid is suspended, the cutter 
lever 206 is raised by the spring 207, and the rotary blade 35b of the 
cutter means K' is also restored to the original position to stand by 
until a subsequent application of the cutting signal. The roller return 
lever 218, etc. act in a manner similar to that described hereinabove when 
the subsequent paper feeding signal is applied. 
In the above-described two embodiments, although the amount of the copy 
paper to be retracted after the cutting operation is suitably determined 
through the association of the apparatus with other mechanisms, or the 
performance of the cutter and the paper feeding roller, or the like, in 
the first embodiment, the proper amount thereof can be set by adjusting 
the spacing between the lower notch 212c of the roller return plate 212 
and the rotation regulating claw 212d thereof, while in the second 
embodiment, such amount can be set by adjusting the position of the 
stopper 221 or the pin 206b. 
Referring now to FIGS. 21 to 25, there is shown a modification of the 
electrophotographic copying apparatus of FIG. 1. In this modification, the 
automatic shut off arrangement of the copying apparatus wherein the main 
motor is turned off when the copy paper sheet is discharged out of the 
apparatus housing is modified to further incorporate a drum switch SD7 
(FIG. 22, FIG. 25(e')) which automatically shuts off the operation of the 
copying apparatus when closed. In other words, although the stopping 
position of the photoreceptor drum 2 is at random, not being particularly 
predetermined in the copying apparatus of FIG. 1, such a position is 
approximately constant in the modification of FIG. 21. Accordingly, the 
period of time required from the initiation of rotation of the 
photoreceptor drum 2 upon turning on of the print switch to the start of 
the copy paper feeding is rendered approximately constant, and by reducing 
this period of time, the time required for copying can be reduced. 
Moreover, since the print switch is not necessary for the manual copy 
paper insertion, it has been so arranged in the modification of FIG. 21 
that the main motor does not run even if the print switch is depressed, 
when the copy paper manual insertion cover plate is lowered to the opened 
position. 
Referring particularly to FIGS. 24 and 25, operation of the automatic shut 
off arrangement of the modification of FIGS. 21 to 25 is described 
hereinbelow. 
It is to be noted that circuit portions or components modified in the 
modification of FIG. 24 as compared with the circuit of FIG. 10 are 
surrounded by dashed lines in FIG. 24 for clarity. 
Upon closure of the print switch SU3, the transistor 96 is turned on, with 
a consequent energization of the relay R3, thus the relay R3 is 
self-retained through closure of the contact 3a1. The capacitor 94 is also 
charged by the closure of the contact 3a1 through a resistor 93, and each 
of the switches SD7, SP6 and SD5. Although the photoreceptor drum 2 starts 
rotating upon closure of the print switch SU3 and the drum stopping switch 
SD7 is opened immediately after rotation of the drum 2 from its stationary 
position, the capacitor 94 is thereafter charged through the contact 2a2 
or a switch SK2 (FIG. 25(n')). Upon depression of the discharge detection 
switch SP6 by the copy paper, the switch SP6 is changed-over to a position 
opposite to that as shown in FIG. 24, without the switching over of the 
drum switch SD6, so long as no copy paper jamming takes place, and the 
capacitor 94 is discharged through the resistor 98. Subsequently, when the 
trailing edge of the copy paper passes the discharge detection switch SP6 
the switch SP6 again returns to the position as shown, in which case, 
since the switch SK2 and the contact 2a2 are both open, the capacitor 94 
is not charged. Upon arrival of the photoreceptor drum 2 at the 
predetermined position, the drum stopping switch SD7 is depressed thereby 
to be closed. In this state, the base potential of the transistor 96 is 
momentarily rendered to be zero through the capacitor 94, and the 
transistor 96 is turned off, so that the relay R3 is released from the 
self-retaining state to cause the main motor M1 to stop. Accordingly, in 
the automatic shut off arrangement of the modification of FIGS. 21 to 25, 
since the drum 2 is caused to stop by the depression of the drum stopping 
switch SD7 (FIG. 25(e')) through rotation of the drum 2, the position 
whereat the drum 2 stops is approximately constant. It is to be noted 
that, in the continuous copying of multiple copy paper sheets in the above 
described arrangement, when the capacitor 94 is discharged, and the copy 
paper discharge detection switch SP6 is restored in the state as shown in 
the drawing, either the contact 2a2 of the relay R2 or the automatic shut 
off prohibiting switch SK2 (newly employed cam switch) is closed to 
prevent the automatic shut off to take place. It should also be noted that 
when the manual insertion cover switch SU5a to SU5c have been 
switched-over, the relay R3 is not energized even if the print switch SU3 
is turned on. 
Still referring to FIGS. 21 to 25, the copy paper jam detection arrangement 
employed in the modification of FIGS. 21 to 25 is described. In the 
modified jam detection arrangement, the copy paper feed switch SS2 and the 
switch 2D2 described as employed in the arrangement of FIG. 1 are 
dispensed with and a jam detection switch SD6 (FIG. 22, FIG. 25(d)) is 
newly employed. 
In FIGS. 24 and 25, upon closure of the print switch SU3 and SU3', the 
relay R3 is energized through actuation of the transistor 96, and is 
self-retained through closure of its contact 3a1, with simultaneous 
closure of the contact 3a2 thereof, in which case, the relay R2 is 
energized through the switches SU5d, SU3', SE1, SC1, etc., and is 
self-retained by the closure of its contact 2a1. Subsequently, the drum 
signal switch SD1 is closed as the drum 2 rotates and energizes the 
latching relay R4-S to close its contact 4a1, thus actuating the copy 
paper feed clutch CL1 for starting the copy paper feeding. When the 
leading edge detection switch SP1 is closed as the copy paper advances, 
the relay R5 is energized and its contact 5b1 is opened, thus the relay R2 
is released from its self-retaining state. When further copy paper 
transportation is normally carried out, the copy paper is continuously 
fed, without the charge of the capacitor 94 flowing into the relay 7 
through the contact 2a3, since the leading edge jam detection switch SD5 
(FIG. 25(h')) is turned on (the opposite state to that shown in the 
drawing) by the drum cam. On the contrary, should a paper jam take place 
at the copy paper feed portion or the cutter portion, since the leading 
edge jamming detection switch SD5 is turned on before turning on of the 
leading edge detection switch SP1, the charge of the capacitor 94 is 
applied to set input of the relay R7 through the contact 2a3 of the relay 
R2 for turning on a jam indication pilot lamp 100 by closing the contact 
7a1 of the relay R7 and also for suspending energization of the relay R1 
by opening the contact 7b2, thus the operation of the copying apparatus is 
suspended. When the leading edge jam detection switch SD5 is turned on by 
the second rotation of the drum 2, if the copy paper is being normally 
transported, and the copy paper discharge detection switch SP6 is switched 
by the copy paper, the charge of the capacitor 94 is discharged through 
the resistor 98, thus no particular inconvenience is experienced. If the 
copy paper, however, should be clogged between the positions of the 
leading edge jam detection switch SD5 and the discharge detection switch 
SP6, the switch SP6 is not switched, and therefore the relay R7 is set 
through actuation of the drum switch SD5 in the manner as described 
earlier for the detection of a jam. 
Subsequently, the jam detection at the copy paper discharging portion is 
described hereinbelow. 
While the copy paper is passing on the copy paper discharge detection 
switch SP6, the charge of the capacitor 94 is discharged through the 
resistor 98 along the path through the switches SD5, SP6 and SD6, in which 
case, the trailing edge detection switch SD6 is so arranged as to be 
turned on by the drum cam after the longest copy paper has switching the 
copy paper discharge detection switch SP6 and is subsequently discharged. 
In this state, if the copy paper continues to switch the discharge 
detection switch SP6 by a copy paper jam thereat, the switch SD6 is 
switched over through rotation of the drum 2 and the capacitor 94 is 
charged through the switches SD6, SP6 and SD5, and a transistor 101 is 
thus turned on. Consequently, the relay R7 is set for indicating a paper 
jam, the mechanical operation of the copying apparatus is suspended, and 
the heaters, etc. are de-energized. If the paper jam should take place 
with the copy paper not depressing the switch SP6, detection is made in 
the manner mentioned earlier. It should be noted here that in the modified 
circuit construction of FIGS. 21 to 25, jam detection at the copy paper 
separating section is not specifically carried out, but is arranged to be 
made collectively with the jam detection between the copy paper leading 
edge and the copy paper discharge portion. It should also be noted that 
the difference in operation of the modification of FIGS. 21 to 25 from the 
embodiment of FIG. 1 resides in that the main relay R8 remains as it is, 
when a jam is detected, while power supply to the temperature control 
circuit and the relay R1 is suspended, and also in that not only the copy 
paper feed device, but also the relay R1 are turned off during a copy 
paper jam at the copy paper feed section. 
In the modification of FIGS. 21 to 25, a copy paper empty detection 
arrangement which is not included in the embodiment of FIG. 1 is further 
incorporated as described hereinbelow. 
In FIGS. 23 and 24, a switch SP8 is employed for copy paper empty 
detection, and is adapted to be closed in the presence of the copy paper. 
For example, a slit (not shown) allowing the actuator of the switch SP8 to 
enter may be formed in a position several tens of centimeters away from 
the final end of the rolled copy paper (i.e., a copy paper length 
sufficient for an operator to hold and pull the final end of the copy 
paper when the feeding rollers 33a and 33b stop upon detection of absence 
of copy paper) for detecting the absence of the copy paper when the 
actuator enters the slit and the switch SP8 is opened. In that case, the 
switch SP8, upon opening thereof, releases the relay R3 from its 
self-retaining state for causing the main motor to stop. It is to be noted 
that the switch SP8 may be replaced by a normally open contact of a 
suitable relay (not shown), with output of a photoelectric element (not 
shown) being utilized for actuation of the relay. In such a case, a slit 
or colored mark is provided at the final end of the roll paper for 
detection thereof by the photoelectric element. 
In the arrangement of FIG. 1, control for turning on or off of the 
developing device is effected by the mechanical latch switch SK1 which is 
latched by the control cam and released from latching by the drum cam. In 
other words, the developing device remaining actuated for a predetermined 
period of time, irrespective of the length of the copy paper. In the above 
arrangement, however, there is a possibility that the toner is 
unnecessarily supplied, since in the developing device, the developing 
roller and the toner supplying roller are driven by the same driving 
source. For further improvements, in the modification of FIGS. 21 to 25, a 
developing switch SP7 (FIG. 25(q)) which is kept closed during passing of 
the copy paper is employed for actuating the developing device. It is to 
be noted that although the position and action of the switch in the 
circuit is similar to those in the embodiment of FIG. 1, the modification 
differs therefrom in that the timing for closure of the switch is 
different, depending on the lengths of the copy paper. In FIG. 21, the 
switch SP7 is disposed in the transportation path of the copy paper before 
the transfer station. 
Since the remaining construction and function of the modified copying 
apparatus of FIGS. 21 to 25 are similar to those of FIGS. 1 to 20, 
detailed description thereof is omitted for brevity. 
As is clear from the foregoing description, according to the 
electrophotograhic copying apparatus of the present invention, the control 
of each of the corona charging and exposure processes is effected through 
the first group of switches disposed along the path of the copy paper 
sheet for aligning the leading edge of the copy paper with that of the 
image on the photoreceptor surface, while the starting of the transfer 
device and function of the copy paper separation process are controlled 
through the control cam driven by actuating signals from one of the 
switches of the first switch group, with the developing and transfer 
functions being adapted to be suspended by the drum cam which rotates as 
one unit with the photoreceptor drum, so that not only the number of 
switches which may give rise to copy paper jamming on the path of the copy 
paper sheet can be reduced, but also undesirable developing and transfer 
at the discontinuity i.e., at the slot portion or the seam of the 
photoreceptor surface are advantageously prevented, thus definite copied 
images of high quality are constantly obtained through the simple control 
circuit. 
Although the present invention has been fully described by way of example 
with reference to the attached drawings, it is to be noted that various 
changes and modifications are apparent to those skilled in the art. 
Therefore, unless otherwise such changes and modifications depart from the 
scope of the present invention, they should be construed as included 
therein.