U.S. patent number 3,819,261 [Application Number 05/194,815] was granted by the patent office on 1974-06-25 for transfer type electrophotographic duplicating apparatus.
This patent grant is currently assigned to Minolta Camera Kabushiki Kaisha. Invention is credited to Masaya Ogawa.
United States Patent |
3,819,261 |
Ogawa |
June 25, 1974 |
TRANSFER TYPE ELECTROPHOTOGRAPHIC DUPLICATING APPARATUS
Abstract
In an electrophotographic duplicating apparatus, a rotatable
drum supporting the photosensitive material has a circumference
slightly greater than the length of the original material to be
copied and is rotated through n+1 revolutions, wherein n is the
number of copies. During the first revolution of the drum the
original image is formed on the photosensitive material. A sheet of
copying material is transferred into position for the image to be
transferred from the photosensitive material. During the second
revolution of the drum the photosensitive material is cleaned in
preparation for copying of another original.
Inventors: |
Ogawa; Masaya (Osaka,
JA) |
Assignee: |
Minolta Camera Kabushiki Kaisha
(Osaka-fu, JA)
|
Family
ID: |
14510031 |
Appl.
No.: |
05/194,815 |
Filed: |
November 2, 1971 |
Foreign Application Priority Data
|
|
|
|
|
Nov 4, 1970 [JA] |
|
|
45-109430 |
|
Current U.S.
Class: |
399/130;
399/297 |
Current CPC
Class: |
G03G
15/307 (20130101) |
Current International
Class: |
G03G
15/30 (20060101); G03G 15/00 (20060101); G03g
015/00 () |
Field of
Search: |
;355/14,8,3,11 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Moses; Richard L.
Attorney, Agent or Firm: Watson, Cole, Grindle &
Watson
Claims
What is claimed is:
1. A transfer type electrophotographic copying machine comprising:
a rotatable drum for supporting photosensitive material and having
a circumference greater than the length of original material to be
copied; an electromagnetic clutch for connecting said drum to a
driving source; means for forming an original image on the surface
of photosensitive material supported on said drum; means for
supplying copying material; transfer means for transferring the
original image on said photosensitive material surface to said
copying material; means for cleaning the residual original image on
said photosensitive material surface; a starting switch; means for
actuating said electromagnetic clutch to rotate said drum through
two revolutions with each closing of said starting switch; control
means for operating said means for forming the original image, said
means for supplying copying material, and said transfer means
during the first revolution of said drum, said control means
deactuating said means for forming an original image, said means
for supplying copying material and said transfer means during the
second revolution of said drum.
2. A transfer type electrophotographic copying machine comprising:
a rotatable drum for supporting photosensitive material and having
a circumference greater than the length of original material to be
copied; an electromagnetic clutch for connecting said drum to a
driving source; means for forming an original image on the surface
of photosensitive material supported on said drum; means for
supplying copying material; transfer means for transferring the
original image on said photosensitive material surface to said
copying material; means for cleaning the residual original image on
said photosensitive material surface; a starting switch; means for
actuating said electromagnetic clutch to rotate said drum through
n+1 revolutions with each closing of said starting switch, wherein
n is the number of copies to be duplicated; control means for
operating said means for forming the original image, said means for
supplying copying material, and said transfer means during n
revolutions of said drum, said control means deactuating said means
for forming an original image, said means for supplying copying
material and said transfer means during the last revolution of said
drum; and means for setting the number of copies to be duplicated
and wherein said means for actuating operates said electromagnetic
clutch to rotate said drum n+1 revolutions.
3. A transfer type electrophotographic copying machine as in claim
2, wherein said photosensitive material is mounted only in the
position on said drum where the original image is formed.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a transfer type
electrophotographic copying machine and, more particularly, to an
electrophotographic copying machine in which a photosensitive sheet
is exchangeably mounted on a rotary drum whereby, and electrostatic
image is formed on the photosensitive sheet and the image is copied
on a transfer sheet.
It is well known that there exist two modes of transfer type
electrophotographic copying machines, and that one of them is a
toner image transfer type in which an electrostatic latent image
formed on a photosensitive sheet is developed and then transferred
to a transfer sheet, and the other one operates such that an
electrostatic latent image formed on a photosensitive sheet is
electrostatically transferred to a transfer sheet and then the
already transferred latent image is developed. The present
invention is applicable to both modes described above.
It is also known that there are various kinds of transfer type
electrophotographic copying machines involved in both modes
described above, and particularly in one kind of the former mode
where a photosensitive surface is formed on the rotary drum, an
electrostatic latent image is formed on the photosensitive surface
by providing an electric charge thereon. A toner is applied to the
photosensitive surface corresponding to the electrostatic image,
then the developed image is transferred by means of a transfer
device to a transfer sheet contacting the photosensitive surface.
The transfer sheet is thereafter fused to complete a copy. In one
kind of the latter mode, a photosensitive surface is formed on the
rotary drum, an electrostatic latent image is formed on the
photosensitive surface thereon while it is being rotated. The
transfer sheet is pressed into contact with the photosensitive
surface and the electrostatic latent image on the photosensitive
surface is transferred to the transfer sheet by means of a transfer
system. Thereafter a development and fixing process for the latent
image on the transfer sheet is carried to effect a complete
copy.
In these previously known types of copying machines, a
photosensitive plate is integrally formed on the rotary drum, and
the functional sections to carry out each aforementioned operation
are arranged around the periphery of the drum. Furthermore, the
length of the photosensitive substance on the drum is actually less
than one-half of the circumference of the drum and approximately
equal to one quarter thereof. This results in that the required
diameter of the drum is undesirably large and the overall volume of
the copying machine which is primarily determined by the diameter
of the drum becomes thereby voluminous. Moreover, when the
photosensitive substance is degenerated on account of the fatigue
phenomenon due to its repeated use, it is required to exchange it
as one body with the drum. Additionally, in the case where plural
sheets of copies for an identical picture image are continuously
required, the time interval between the first copy and the second
copy is effectively increased.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a transfer type
electrophotographic copying machine which is built up in a small
size by virtue of a smaller diameter of the rotary drum.
It is another object of the present invention to provide a transfer
type electrophotographic copying machine in which, for the purpose
of decreasing the diameter of the rotary drum the copying process
is carried out during two complete revolutions of said drum.
It is still another object of the present invention to provide a
transfer type electrophotographic copying machine wherein the
copying operation is speeded up for obtaining plural copies of
originals in such a way that during the second revolution of the
drum, concurrently with the conveyance of the transfer sheet for
the first copy having already been transferred during the first
revolution of the rotary drum and the cleaning of the
photosensitive sheet on the rotary drum, the electric charge on the
photosensitive sheet and the image formation thereon for the second
copy and then the transfer of the image onto the transfer sheet for
the second copy are performed.
It is a still further object of the present invention to provide a
transfer type electrophotographic copying machine by means of
which, when a continuous copying operation is carried out, n sheets
of transferred copies are obtained as a result of the continuous
n+1 revolutions of the rotary drum.
It is one of the other objects of the present invention to provide
an electric control circuit including a plurality of micro-switches
and relays which are activated by the rotary drum of the transfer
type electrophotographic copying machine in order to attain all
objects described above.
SUMMARY OF THE INVENTION
The present invention relates to a transfer type
electrophotographic copying machine wherein a photosensitive
surface on the rotary drum is nearly the same size as that of an
original to be copied and is exchangeably mounted on said rotary
drum. The axial length of the drum is slightly longer than the
length of one side of the photosensitive surface and its
circumference slightly longer than the length of another side of
the photosensitive surface. During the first revolution of the
rotary drum, a switch circuit operates so that an image of a
stationary original is projected by means of a slit type exposure
optical system to form an electrostatic image on the photosensitive
surface. The electrostatic latent image is then transferred onto a
transfer sheet, and thereafter the transfer sheet is separated from
the rotary drum. During the next revolution of the rotary drum, the
switching circuit is operated so as to clean the photosensitive
surface and convey the transfer sheet. But in the case where plural
copies are continuously produced, the switching circuit is operated
by virtue of the indication of a copy sheet counting device in such
a way that carried out in the period of the second revolution of
the rotary drum are operations of the image formation on the
photosensitive sheet and the transfer thereof which operations are
both achieved in the same manner as in the period of the first
revolution of the rotary drum, as well as the conveyance of the
already transferred transfer sheet and the cleaning of the
photosensitive sheet, whereby, n sheets of copies can be obtained
by virtue of the n+1 revolutions of the rotary drum.
Since the peripheral surface of the rotary drum is made slightly
larger than the area of an original to be copied, as described
above, the diameter of the rotary drum is decreased and the volume
of a transfer type electrophotographic copying machine is also
minimized. Moreover, the exchange of the photosensitive surface can
be easily carried out, because the photosensitive surface according
to the present invention is exchangeably mounted with respect to
the rotary drum.
In addition, the present invention contributes to the improvement
of the copying efficiency not only by speeding up the rotational
angular velocity of the rotary drum in such a way that a copy of
one sheet is completed at the termination of the two revolutions of
the rotary drum, but also by eliminating the wasteful rotation of
the rotary drum in each copying cylce, in the case where a large
number of copies are continuously produced. The switching circuit
is operated so as to complete the copying cycle of the first copy
in the period of the second revolution of the rotary drum, and also
to concurrently carry out the image formation for the second copy
onto the photosensitive surface and the transfer thereof in the
identical period of the second revolution thereof, whereby, n
sheets of copies can be produced by virtue of the n+1 revolutions
of the rotary drum.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially broken away side view showing the
construction of the essential parts of an embodiment of a transfer
type electrophotographic copying machine in accordance with the
present invention;
FIG. 2 is a segmentary elevational sectional view showing a
mechanism for synchronizing the rotary drum with a slit type
exposure otical system for the same embodiment as FIG. 1;
FIG. 3 is a side view showing the relationship of the rotary drum
and a microswitch group of a switching circuit for the same
embodiment as FIG. 1;
FIG. 4 is a control switching circuit diagram for the same
embodiment as FIG. 1; and
FIG. 5 is a partially broken away side view showing the
construction of essential parts of an alternative preferred
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1-4 show an embodiment of the toner image transfer type
copying machine in accordance with the present invention. With
reference to FIG. 1, reference numeral 1 is a rotary drum of a
small diameter having its peripheral surface made slightly larger
than that of a photosensitve surface P which is of a nearly the
same configuration as an original so that the photosensitive
surface P is capable of being exchangeably mounted thereover. The
rotation of a motor 3, which is always running during the operation
as a drive source, is transmitted via an electromagnetic clutch
means 4 to the rotary drum 1 which is thereby rotated about its
shaft 2 journaled to the main body of the copying machine. Numeral
5 denotes an electric charging device, such as a direct current
corona discharge unit, which is mounted on the main body proximate
to the rotating peripheral surface of the rotary drum 1, and which
is capable of providing the photosensitive surface P with an
electric charge. Numeral 6 denotes an exposure window of a slit
type exposure system. The exposure system comprises a pair of guide
rails 8 and 9 which are fixed to the main body so as to be parallel
with an original O placed on an original station 7 which is also
fixed atop the main body of the copying machine. A second carrier B
which is provided with two mirrors M.sub.2 and M.sub.3, is capable
of travelling along the rail 9 by virtue of rollers D. A first
carrier A which is provided with an original illuminating device I
and a first mirror M.sub.1 is disposed on the rollers D so as to be
capable of travelling under the guidance of the rail 9. Further
disposed on and fixed to the main body are an objective lens L
which is positioned in the path of the lightrays reflected by
movable mirror M.sub.3 and a fixed mirror M.sub.4. The lightray
transmitted through the objective lens L is then reflected towards
the exposure window 6.
As shown in FIG. 2, a wheel 10 which is coaxial with and of the
same diameter as the rotary drum 1 is affixed by a normally run
belt 11 and an inversely run belt 12 which are individually wound
on the peripheral surface thereof.
Belt 11 is connected to a connector 15 fixed to the fore end of the
first carrier A via a pulley 13 which is located between both guide
rails 8 and 9 and rotatably fixed to the main body. Similarly, belt
12 is connected to a connector 16 fixed to the back end of the
first carrier A via a pulley 14. A spiral spring 17 is located
between the inner face of the wheel 10 and the peripheral face of
the shaft 2, and partially wound on and fixed to the shaft 2, as
shown in the drawing.
The first carrier A and second carrier B are mutually connected
through rollers D mounted on second carrier B in such a way that,
when the first carrier A is travelling in a given direction the
second carrier B is forced to travel in the same direction at a
speed of one-half as much as that of the first carrier A.
Further provided between the rotary drum 1 and the wheel 10 is an
electromagnetic clutch CL which is shown in FIG. 4. Members 1 and
10 being constituted so as to be mutually connected by virtue of
the electromagnetic clutch CL so that both members can be rotated
as a body, or to be released from each other by the clutch means.
That is, when both members are connected, the rotary drum 1 drives
the wheel 10 so as to have it rotated at the same peripheral speed.
The wheel 10 is thereby rotated counterclockwise as shown in FIG. 2
so as to have the spring 17 wound up. Belt 11 causes the first
carrier A to travel at the same speed as said peripheral speed from
the right to the left, and the illuminating device I illuminates
the original O successively from the right to the left.
Consequently, the reflected lightrays of the original O are
successively reflected by the mirrors M.sub.1, M.sub.2 and M.sub.3.
Mirrors M.sub.2 and M.sub.3 are mounted on the second carrier B
which is interconnected through roller D with the first carrier A
so as to be carried at a speed of one-half as much as that of first
carrier A. The mirrors M.sub.2 and M.sub.3 are both capable of
functioning so as to keep the length of the light path between the
objective lens 1 and the original O at a constant value at all
times. The scanned lightrays are sequentially reflected by the
fixed mirror M.sub.4 towards the exposure window 6 where the
lightrays sequentially provide the exposure to make an image on the
photosensitive surface P on rotary drum 1 while said drum is
passing under the exposure window 6 synchronously with the scanning
operation of the original O.
At the end of the normal stroke of the first carrier A, a return
switch SW is located which is operated by the front end of the
first carrier A during its leftwards motion. The electromagnetic
clutch CL then disconnects the wheel 10 from the rotary drum 1. The
wheel 10 is thereby rotated in a reverse direction due to the
returning force of the energized spring 17, so that both carriers A
and B are returned to their respective initial positions by virtue
of the reversely run belt 12 as shown in FIG. 2.
Referring again to FIG. 1, numeral 18 denotes a development device
which develops an electrostatic latent image formed on the
photosensitive surface P by means of a toner, and numeral 19
denotes a transfer system consisting of a corona discharge unit 20
and two transfer sheet pressing rollers 21 and 21'. This transfer
system 19 transfers a toner image formed on the photosensitive
surface P onto a transfer sheet 25 which is fed one by one from a
transfer sheet reservoir 22 by means of a feeding roller 24 driven
by a motor 23.
Reference numeral 26 denotes a separating device which separates
the transfer sheet 25 from the photosensitive surface P by means of
air injection.
Reference numeral 27 denotes a conveying device consisting of an
endless belt for carrying the transfer sheets separated from the
photosensitive surface P and a pair of rollers. Numeral 28 denotes
a fixing device consisting of an electric heater which is arranged
in the passageway of the conveying device 27. Further, numeral 29
denotes a storage tray for completed copies, and numeral 30 denotes
a cleaner for cleaning the photosensitive surface P in order to
prepare for the next image formation thereon upon completion of the
preceding transfer process.
With reference to FIG. 3 and FIG. 4, in this preferred embodiment,
a cam plate 31 as shown in FIG. 3 is integrally made up so as to be
of the same diameter as that of, and coaxial with, the rotary drum
1, and a control projection 32 is formed on the cam plate 31 around
which are arranged a plurality of microswitches SW.sub.1, SW.sub.2,
SW.sub.3, SW.sub.4, SW.sub.5, SW.sub.6, SW.sub.7, SW.sub.8 and
SW.sub.9. Thereby, the control projection 32 is capable of
successively activating these microswitches in response to the
revolution of the rotary drum 1. At the starting time of a copying
operation, the microswitch SW.sub.1 is opened by the projection 32,
and the electromagnetic clutch 4 is accordingly released to have
the rotary drum 1 stopped.
In FIG. 4, if the power source is switched on, a current is at all
times provided to actuate the drive motor 3, the separating device
26, the heater 28 of the fixing device, and the cleaner 30.
Now, if a starting switch S.sub.S shown in FIG. 1 is manually
pressed, switches S.sub.S1 and S.sub.S2 are both closed, a relay
RY.sub.1 is actuated by the closed switch S.sub.S1 so as to close
relay switches 1A.sub.1, 1A.sub.2, 1A.sub.3, 1A.sub.4 and 1A.sub.5,
and concurrently with this closing motion, the relay RY.sub.1 is
placed under the self holding status due to the closed switch
1A.sub.1. Simultaneously, the electromagnetic clutch 4 is connected
to the drive motor due to the closed switch S.sub.S2 to get the
rotary drum 1 to start its revolution. Immediately after the rotary
drum 1 has started its revolution, the microswitch SW.sub.1 is
closed by the projection 32 of the cam plate 31. Accordingly, even
if the starting switch S.sub.S2 is thereafter opened, the
electromagnetic clutch 4 is capable of keeping its connection with
the drive motor 3 so as to maintain the continuous revolution of
the rotary drum 1. When the microswitch SW.sub.2 is closed by the
projection 32, a relay RY.sub.2 is activated via the closed relay
switch 1A.sub.2, so that it closes both relay switches 2A.sub.2 and
2A.sub.3, as well as is in a self holding mode owing to the
functioning of both relay switches 1A.sub.3 and 2A.sub.1.
By virtue of the closed relay switch 2A.sub.2, the charging device
5 is energized to actuate the corona discharge. The photosensitive
sheet P on the revolving rotary drum 1 is thereby endowed
successively with a uniform electric charge.
When the microswitch SW.sub.3 is closed by the projection 32, a
current flows through a relay RY.sub.3 via the relay switch
1A.sub.4 in the closed status so that the relay RY.sub.3 is
activated to get a relay switch 3A.sub.1 to close, thereby it keeps
a relay switch 3A.sub.2 closed as well as the relay RY.sub.3 which
is held owing to the relay switch 3A.sub.1. Accordingly, the rotary
drum 1 and the wheel 10 are connected by virtue of the energized
electromagnetic clutch CL, so that the wheel 10 also begins to
rotate. Consequently, as described hereinbefore, the first carrier
A and the second carrier B are carried leftwards, and the
illuminating device I is simultaneously lighted. Accordingly, an
image of the original O is successively projected onto the
uniformly charged photosensitive surface P.
When the microswitch SW.sub.4 is closed by the projection 32, a
relay RY.sub.4 is activated via closed relay switch 2A.sub.3, so
that it is self-held due to the microswitch SW.sub.2 and a relay
switch 4A.sub.1, as well as it closes relay switches 4A.sub.2 and
4A.sub.3. Consequently, the development device 18 is actuated by
the closed relay switch 4A.sub.2, so that the photosensitive
surface P having an electrostatic latent image formed thereon is
successively developed by means of the toner process while the
photosensitive surface P is passing through the development device
18.
When the microswitch SW.sub.5 is closed by the projection 32, relay
RY.sub.5 is activated via closed relay switch 1A.sub.5, so as to
close the microswitch SW.sub.7 and its relay switch 5A.sub.2,
thereby the relay RY.sub.5 is self-held, as well as closes a relay
switch 5A.sub.1 so as to actuate motor 23 for feeding transfer
sheets. Accordingly, the feeding roller 24 begins to feed one of
the transfer sheets into the transfer system 19.
Subsequently, when the microswitch SW.sub.6 is closed by the
projection 32, a relay RY.sub.6 is activated via closed relay
switch 4A.sub.3, so as to close the microswitch SW.sub.4 and a
relay switch 6A.sub.2, thereby the relay RY.sub.6 is self-held as
well as closes a relay switch 6A.sub.2. Consequently, the corona
discharge unit 20 of the transfer system 19 is actuated and a toner
image formed on the photosensitive surface P is thereby transferred
onto the transfer sheet 25.
When the microswitch SW.sub.7 is operated by the projection 32, the
relay RY.sub.5 is released so as to deactivate motor 23. The
transfer sheet having an image thereon is separated from the
photosensitive surface P by the air injection of the separating
device 26 which is always working, and the separated transfer sheet
is sent to the fixing unit 28 where it is heated and fixed by a
heater.
When the microswitch SW.sub.8 is operated by the projection 32 of
the cam plate 31, in the case where one copy is indicated by the
copying sheet counter device 34, the relay RY.sub.1 is released so
that the corona discharge by the electric charging device 5 is
terminated.
Finally, when the microswitch SW.sub.9 is operated by the
projection 32, if one copy is indicated by the copy sheet counting
device 34 as described above, a solenoid 33, which is usually
functional to lessen said indicated number one by one, is released
from the operation as described above.
When the projection 32 is rotated so as to open the microswitch
SW.sub.1, the electromagnetic clutch 4 is still kept actuated
through the relay switch 6A.sub.3 which is then kept closed,
thereby the clutch 4 is still kept connected with the drive motor 3
so as to maintain the continuous revolution of the rotary drum 1.
Accordingly, the photosensitive surface P is capable of being
cleaned by the cleaner 30 which is working at all times.
Meanwhile, the first carrier A of a slit type exposure device is
moved to the left end of the guide rail 8. (The location is shown
by broken lines in FIG. 1 and FIG. 2.). Just before the trailing
end of the photosensitive surface P has passed through under the
exposure window 6, and thereby acts on the return switch SW so as
to have it opened, the illuminating device I is accordingly
extinguished, and the clutch CL connecting the rotary drum 1 with
the wheel 10 is concurrently released. The wheel 10 is thereby
rotated counterclockwise by the energized spring 17. Consequently,
the first and the second carriers A and B of the slit type exposure
system are returned to their respective right ends. (The positions
are shown by full lines in FIG. 1 and FIG. 2.). This return
operation is quickly accomplished by suitably setting the biasing
force of the spring 17 so as to get the return motion to be
completed before the microswitch SW.sub.2 is again operated by the
projection 32.
On account of the further revolution of the rotary drum 1, even if
the projection 32 is situated so as to act again on the microswitch
SW.sub.2, since the relay switches 1A.sub.2, 1A.sub.3 have been
already opened, the relay RY.sub.2 is not operated so that the
electric charging device 5 is not actuated. However, since the
relay RY.sub.4 is thereby released from its self holding situation,
the operation of the development device 18 is terminated.
The microswitch SW.sub.3 is then actuated by the projection 32;
however, since the relay switch 1A.sub.4 has been already opened,
the relay RY.sub.3 is not actuated, the clutch CL is not therefore
connected, the illumination device I of the slit type exposure
system is not lighted, and the leftward movement of the first
carrier A and the second carrier B does not take place.
The microswitch SW.sub.4 is next actuated by the projection 32;
however, since the relay switch 2A.sub.3 has been already opened,
the development device 18 is not actuated, but the relay RY.sub.6
is released from its self-holding situation by the concurrent
operation of the microswitch SW.sub.4. Accordingly, the discharge
by the corona discharge unit 20 of the transfer system 19 is
terminated. That is, the trailing end of the transfer sheet 25 just
passes through the transfer system 19 at this moment.
The microswitch SW.sub.5, SW.sub.6 and SW.sub.7 are next actuated
by the projection 32; however, since the relay switches 1A.sub.5
and 4A.sub.3 have been already opened, the relays RY.sub.5 and
RY.sub.6 are not operated, the feeding device 23 and 24 is not
actuated, and the corona discharge unit 20 of the transfer system
19 is also not operated.
After the projection 32 has passed through the microswitches
SW.sub.8 and SW.sub.9, if it opens the next microswitch SW.sub.1,
since the relay switch 6A.sub.3 has been already opened, the
electromagnetic clutch 4 is disconnected, so that the revolution of
the rotary drum 1 is terminated. That is, this microswitch SW.sub.1
is a functional switch for detecting the leading end of the
photosensitive surface P on the rotary drum 1.
Additionally, since the photosensitive surface P is cleaned by the
cleaner 30 two times, i.e., in the period of the first revolution
of the rotary drum 1, and in the period of the second revolution
thereof, accordingly, the cleaning thereof is fully carried into
effect.
Furthermore, during the second revolution of the rotary drum 1, the
transfer sheet 25 which has been transferred during the first
revolution thereof is sent out through the conveying passage 27
while it is concurrently heated and fixed by the fixing unit 28,
and finally put in a tray 29 for the storage of completed
copies.
The descriptions shown hereinabove are all concerned with such a
case where the indication of a counting device 34 for setting the
number of sheets to be copied is set to "1" in order to obtain only
one copy of an original. However, in the case where the device is
set for two sheets or an unlimited number M of sheets, each contact
point of the indicating scale and its pointer are short-circuited
across the microswitch SW.sub.8. Therefore, even though the
projection 32 acts on the microswitch SW.sub.8 during the first
revolution of the rotary drum, the self-holding of the relay
RY.sub.1 is maintained, and the relay switches 1A.sub.1, 1A.sub.2,
1A.sub.3, 1A.sub.4 and 1A.sub.5 are also kept in the closed status.
Consequently, the same operation as that carried out during the
first revolution of the rotary drum 1, after the microswitches
S.sub.S1 and S.sub.S2 are closed by pressing the starting button
S.sub.S for starting the first revolution of the rotary drum 1, is
again carried out during the second revolution. That is, during the
second revolution of the rotary drum the surface P of the drum is
cleaned after the exposure and fixing of the first copy and the
transfer of the first transfer sheet. The second image formation on
the photosensitive surface P and the transfer of the image thereof
to the next transfer sheet for the purpose of obtaining the second
copy is also effected. On account of the operation of the switch
SW.sub.9 which is actuated by the projection 32 after the switch
SW.sub.8 has been actuated thereby, a solenoid is actuated so that
the indication of the copying sheet amount pre-set device 34 is
lessened by one step.
Accordingly, if, in general, the indication of the copy sheet
counting device has been manually set in advance so as to obtain n
sheets of copies, when the starting button S.sub.S is pressed, n +
1 revolutions of the rotary drum 1 are automatically carried out so
that n sheets of copies are continuously produced.
The second embodiment of the present invention shown in FIG. 5 is
concerned with an electrophotographic copying machine of the latent
image transfer type, wherein, the development device 18 confronting
the rotary drum 1 is removed, and a wet development device 18' is
instead disposed in the path of the conveying passage of the
transfer sheet. Also disposed instead of the corona discharge unit
20 of the transfer device 19 is a conductive roller 20' which has
been grounded or charged by a potential of the inverse polarity
with that of the electrostatic latent image. Moreover, the cleaning
device 30 is replaced with another cleaner 30' which is functional
to wipe out the residual electrostatic image, and a dry fixing unit
28' is arranged instead of thermal fixing unit 28. Also removed are
the microswitches SW.sub.4 and SW.sub.6 which have controlled both
operations of development device 18 and corona discharge unit 20.
Therefore, the relay switch 6A.sub.3 of the relay RY.sub.6 which
has been operated by the removed microswitch SW.sub.6 for
activating the second revolution of the rotary drum 1 is now
functional as a relay switch of the relay RY.sub.3 which is
operated by the microswitch SW.sub.3.
* * * * *