U.S. patent number 3,784,297 [Application Number 05/120,132] was granted by the patent office on 1974-01-08 for photocopying machine.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Yoshio Ito, Hajime Katayama, Hiroshi Nitanda, Masaru Yamaguchi.
United States Patent |
3,784,297 |
Ito , et al. |
January 8, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
PHOTOCOPYING MACHINE
Abstract
An electrophotographic copying machine of this invention has an
original holder reciprocating on the upper surface of an
electrophotographic photosensitive member which is rotatably fixed
to the supporting device therefor. The charging device is arranged
on one side of the photosensitive member. The copying machine
further includes optical system for slit exposure, developing
device, fixing device and cleaning device, which are arranged on
the other side of the photosensitive member. Copy sheet feeding
device, image transfer device are also arranged below the
photosensitive member.
Inventors: |
Ito; Yoshio (Tokyo,
JA), Katayama; Hajime (Tokyo, JA), Nitanda;
Hiroshi (Tokyo, JA), Yamaguchi; Masaru (Yokohama,
JA) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JA)
|
Family
ID: |
26356967 |
Appl.
No.: |
05/120,132 |
Filed: |
March 2, 1971 |
Foreign Application Priority Data
|
|
|
|
|
Mar 11, 1970 [JA] |
|
|
45/20075 |
Apr 15, 1970 [JA] |
|
|
45/32112 |
|
Current U.S.
Class: |
399/116; 118/679;
271/259 |
Current CPC
Class: |
G03G
21/1647 (20130101); G03G 21/1604 (20130101); G03G
21/1628 (20130101); G03G 15/30 (20130101); G03G
2221/16 (20130101); G03G 2221/1618 (20130101); G03G
2221/1636 (20130101); G03G 2221/1654 (20130101); G03G
2221/1657 (20130101); G03G 2221/18 (20130101); G03G
2221/1624 (20130101); G03G 2221/163 (20130101); G03G
2221/1606 (20130101); G03G 2221/1672 (20130101) |
Current International
Class: |
G03G
15/30 (20060101); G03G 21/16 (20060101); G03G
15/00 (20060101); G03g 015/08 (); G03g
015/00 () |
Field of
Search: |
;355/3,8,10,11,14
;271/57 ;118/637,7,4,8 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Greiner; Robert P.
Attorney, Agent or Firm: Ward, McElhannon, Brooks, &
Fitzpatrick
Claims
We claim:
1. In a photocopying machine including apparatus for projecting an
image on a photosensitive member, means for developing said image
on said photosensitive member, and means for transferring said
developed image onto a sheet of copy medium, the improvement
comprising means for activating said developing means including
first and second sensing means disposed in spaced-apart relation
with each other in the path of the copy medium, and means for
energizing said developing means from the time the leading side
edge of the copy medium reaches said first sensing means to the
time the trailing side edge of the copy medium passes said second
sensing means.
2. A photocopying machine as defined in claim 1 wherein both of
said first and second sensing means are microswitches.
3. A photocopying machine as defined in claim 1 wherein said first
and second sensing means each comprises a light source, a pair of
mirrors and a photoelectric effect element.
4. In a photocopying machine including a photosensitive drum,
illumination light source means for illuminating an object to be
copied, a mirror and lens system for projecting a light image of
said object on said drum, reflector means surrounding said light
source means and having a portion cut away, and shielding means for
said light source means having a cut-away portion aligned with said
cut-away portion of said reflector and disposed with respect to
said mirror and lens system to permit pre-exposure of said
drum.
5. An electrophotographic copying machine comprising a housing, an
original holder reciprocable upon the upper surface of said
housing, driving means for reciprocating said original holder, an
electrophotographic photosensitive drum disposed substantially at
the center of said housing, supporting means for rotatably mounting
said photosensitive drum within said housing, charging means, an
optical system, and developing means disposed on one side of said
electrophotographic photosensitive drum, fixing means and cleaning
means disposed on the side of said electrophotographic
photosensitive drum opposed to said one side thereof, for fixing a
developed image on a sheet of copy medium and for cleaning said
photosensitive drum, respectively, copy medium feeding means, and
image transfer means disposed below said electrophotographic
photosensitive member, wherein said electrophotographic
photosensitive drum and supporting means are removable upwardly of
said housing, and wherein said feeding means includes means for
intermittently activating said developing means to operate only
during a predetermined period of movement of said copy medium; and
wherein said feeding means includes a first pair of feed rollers
and a pair of guide plates mounted on a fixed portion of said
housing and a second pair of feed rollers mounted to a side wall of
said housing which may be opened so that the path of the copy
medium may be accessible.
6. An electrophotographic copying machine comprising a housing, an
original holder reciprocable upon the upper surface of said
housing, driving means for reciprocating said original holder, an
electrophotographic photosensitive drum disposed substantially at
the center of said housing, supporting means for rotatably mounting
said photosensitive drum within said housing, charging means, an
optical system, and developing means disposed on one side of said
electrophotographic photosensitive drum, said optical system
including a mirror and lens system for projecting a light image on
said drum, illumination light source means, reflector means
surrounding said light source means and having a portion cut away,
and shielding means for said light source means, wherein said
shielding means is mounted for removal from one side of said
housing, and has a cut-away portion aligned with said cut-away
portion of said reflector to permit pre-exposure of said drum,
fixing means and cleaning means disposed on the side of said
electrophotographic photosensitive drum opposed to said one side
thereof, for fixing a developed image on a sheet of copy medium and
for cleaning said photosensitive drum, respectively, copy medium
feeding means, and image transfer means disposed below said
electrophotographic photosensitive member, wherein said
electrophotographic photosensitive drum and supporting means are
removable upwardly of said housing, and wherein said feeding means
includes means for intermittently activating said developing means
to operate only during a predetermined period of movement of said
copy medium.
7. An electrophotographic copying machine comprising a housing, an
original holder reciprocable upon the upper surface of said
housing, driving means for reciprocating said original holder, an
electrophotographic photosensitive drum disposed substantially at
the center of said housing, supporting means for rotatably mounting
said photosensitive drum within said housing, charging means, an
optical system, and developing means disposed on one side of said
electrophotographic photosensitive drum, fixing means and cleaning
means disposed on the side of said electrophotographic
photosensitive drum opposed to said one side thereof, for fixing a
developed image on a sheet of copy medium and for cleaning said
photosensitive drum, respectively, copy medium feeding means, and
image transfer means disposed below said electrophotographic
photosensitive member, wherein said electrophotographic
photosensitive drum and supporting means are removable upwardly of
said housing, and wherein said feeding means includes means for
intermittently activating said developing means to operate only
during a predetermined period of movement of said copy medium, said
means for activating said developing means including first and
second sensing means disposed in spaced-apart relation with each
other in the path of the copy medium, and means for activating said
developing means from the time the leading side edge of the copy
medium reaches said first sensing means to the time the trailing
side edge of the copy medium passes said second sensing means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photocopying machine and more
particularly an electrophotographic copying machine of the type in
which an original stand is reciprocated, exposure is made through a
slit and an electrophotographic photosensitive member is in the
form of a rotary drum. More specifically the present invention
relates to an electrophotographic copying machine of the type in
which an electrophotographic photosensitive member consisting of a
photoconductive layer sandwiched between an insulating surface
layer and an insulating or conducting member is used and an
original in the form of a sheet or a thick original may be
reproduced automatically, rapidly and economically reproduced upon
copy media such as sheets of copy paper or the like (to be referred
to as "copy paper" hereinafter in this specification).
2. Description of the Prior Art
In general, in the electrophotographic copying machines available
in the market, both of ordinary sheets of paper and photosensitive
sheets are used for reproducing an original in the form of a sheet
or a thick original. The reproduction cost is high in the
electrophotographic copying machine of the type using
photosensitive sheets. Therefore the electrophotographic copying
machines of the type using paper sheets are widely used because the
cost per copy is very low. However, the electrophotographic
photosensitive members which are repetitively used must be replaced
when it is damaged. The advantages of the electrophotographic
copying machines of the type using paper sheets will be cancelled
if the replacement of the electrophotographic photosensitive
members is difficult or the re-adjustment of the
electrophotographic copying machines is required after the
replacement.
SUMMARY OF THE INVENTION
One of the objects of the present invention is to provide an
improved electrophotographic copying machine (to be referred to as
"photocopying machine" for brevity hereinafter) which is compact in
size because a space required for replacement of an
electrophotographic photosensitive member (to be referred to as
"sensitive member or drum" for brevity hereinafter) may be reduced
to the minimum and which facilitates the inspection and maintenance
of various means required for the electrophotographic process and
disposed around the sensitive drum or member after its removal.
Another object of the present invention is to provide an improved
photocopying machine in which various processing means are arranged
as units so that the mounting or removal and inspection and
maintenance of these various units may be much facilitated.
According to the present invention there is provided an improved
photocopying machine in which an original holder upon which is
placed an original to be copied is disposed upon the top of the
photocopying machine for reciprocal movement and the copy papers
are fed one by one by feeding means and discharged after the
copying operation.
At the center of the main body of the housing is disposed a rotary
sensitive drum to the peripheral surface of which is applied a
lamination consisting of a photoconductive layer sandwiched between
an insulating surface layer and an insulating or conducting layer.
Around the sensitive drum are disposed first charging means,
simultaneous exposure-charging means, whole-surface-illumination
means, developing means, third charging means, image transfer means
and cleaning means in the order named in the direction of rotation
of the rotary sensitive drum.
The rotary sensitive drum is positively or negatively charged by dc
corona discharge generated by the first charging means. The dc
corona discharge whose polarity is opposite to that of the dc
corona discharge by the first charging means or ac corona discharge
is applied to the rotary sensitive drum by the simultaneous
exposure-charging means simultaneously when a light or radiation
image of the original to be reproduced is exposed or projected upon
the rotary sensitive drum. By the whole-surface exposure means, the
whole surface of the rotary sensitive drum is uniformly exposed so
as to increase the contrast of the image. The electrostatic latent
image thus formed may be developed into a positive or negative
toner image by the toner which is charged with a polarity opposite
to or same as that of the latent image by the developing means. The
third charging means is not necessarily required, but may be used
with a desired polarity so that the image transfer efficiency may
be improved. The toner image thus developed may be transferred by
the image transfer means to a copy paper. After the image transfer
the toner which still remains upon the rotary sensitive drum is
removed or cleaned by the cleaning means. Thus one cycle of copying
or reproduction operation is completed as far as the rotary
sensitive drum is concerned. The copy paper is separated from the
rotary sensitive drum by a separating means and fixed in the fixing
means and then discharged out of the photocopying machine.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view illustrating the outer apperance of a
photocopying machine in accordance with the present invention;
FIG. 2 is a longitudinal front view thereof;
FIG. 3 is a transverse sectional view thereof illustrating a rotary
sensitive drum unit and a reciprocable original holder;
FIG. 4 is a top view of the rotary sensitive drum unit;
FIG. 5 is a perspective view of the original holder and its
reciprocating means;
FIG. 6 is a perspective view illustrating the mounting and removal
of the rotary sensitive drum unit;
FIG. 7 is a view illustrating the mounting and removal of means for
illuminating the original and charging means unit;
FIG. 8 is a sectional view of a developing means;
FIG. 9 is a perspective view illustrating means for supplying the
developing agent to the developing means;
FIG. 10 is a fragmentary front view thereof on enlarged scale;
FIG. 11 is a side view thereof;
FIG. 12 is a top view of means for circulating the developing agent
in the developing means;
FIG. 13 is a longitudinal front view of another embodiment of means
for supplying the developing agent in accordance with the present
invention;
FIG. 14 is a side view thereof;
FIGS. 15 and 16 are side views illustrating one embodiment of means
for opening or closing a discharge opening of a hopper;
FIGS. 17 and 18 are front view illustrating means for adjusting an
angle of rotation of a spiral feed roller disposed in the hopper
shown in FIGS. 15 and 16;
FIG. 19 is a perspective view of the opening and closing means
shown in FIGS. 15 and 16;
FIG. 20 is a front view of one embodiment of a passage of copy
paper;
FIG. 21 is a fragmentary perspective view thereof on enlarged
scale;
FIG. 22 is a front view of one embodiment of means for controlling
the activation and de-activation of the developing means;
FIG. 23 is an electric circuit diagram thereof;
FIG. 24 is a perspective view of one embodiment of fixing means in
accordance with the present invention;
FIG. 25 is a front view thereof;
FIG. 26 is a longitudinal section view thereof;
FIG. 27 is a sectional view of one embodiment of cleaning means in
accordance with the present invention;
FIG. 28 is a fragmentary top view thereof on enlarged scale;
FIG. 29 is a sectional view of another embodiment of cleaning means
in accordance with the present invention;
FIGS. 30 through 33 are views illustrating brushes used in the
cleaning means for removing the developing agent;
FIG. 34 is a view illustrating one embodiment of means for moving
the developing agent removed in the cleaning means to a collection
box;
FIG. 35 is for explanation of a method for applying on and removing
from a roller a cleaning material in accordance with the present
invention;
FIG. 36 is a front view illustrating means for controlling the
rotation of a cleaning roller;
FIG. 37 is a sectional view thereof;
FIG. 38 is a longitudinal sectional view of one embodiment of
charging means in accordance with the present invention;
FIG. 39 is a top view thereof; and
FIG. 40 is a transverse sectional view thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a perspective view of an embodiment of the present
invention showing its outer apperance. Upon an original holder 11
is placed an original with its surface faced down. The original
holder 11 is reciprocated for carrying out the slit exposure. The
sheets of copy paper P are fed one by one by a feeding means,
processed by an electrophotographic device and discharged out of an
outlet 12.
Referring to FIG. 2, upon the peripheral surface of a drum 2
rotating in the direction indicated by the arrow is formed an
electrophotographic sensitive layer 1 consisting of a
photoconductive layer sandwiched between a surface insulating layer
and a conducting or insulating layer. Around the rotary drum 2 are
disposed in the order named a first charging means 3, a
simultaneous exposure-charging means 5, a whole-surface exposure
means 6, a developing means 7, a third charging means 8, a transfer
means 9 and a cleaning means 10.
The DC corona discharge is imparted by the first charging means 4
to the surface of the rotary sensitive drum 2 so that the sensitive
layer 3 may be positively or negatively charged. By the
simultaneous exposure-charging means 5 the DC corona discharge
having the polarity opposite to that applied by the first charging
means 4 or the AC corona discharge is applied to the sensitive
layer 3 simultaneously when a light or radiation image of the
original to be copied is projected upon the sensitive layer 3 or
drum 1 to produce an electrostatic image.
Thereafter by the whole-surface exposure means 6 such as
fluorescent lamp the electrostatic latent image is uniformly
illuminated so as to increase the action of the latent image as the
external field, thereby increasing the contrast of the
electrostatic latent image. By use of the toner having the polarity
opposite to that of the electrostatic latent image, it is developed
by the developing means 7. Alternatively, the electrostatic latent
image may be developed into a negative image by use of the toner
having the same polarity as that of the latent image. It is
preferable to use the magnet brush or fur brush developing
method.
The third charging means 8 is not necessarily required. However, it
is used with a suitable polarity so as to improve the efficiency of
transferring to the copy paper P the toner image formed upon the
sensitive drum 1. The toner image is transferred electrostatically
to the copy paper P by the transfer means 9. The toner still
remained upon the sensitive drum 1 after the image transfer is
wiped off by cleaning rollers in the cleaning means 10.
The copy paper P upon which is transferred the toner image from the
sensitive drum 1 is separated from the sensitive drum by a
separating means, fixed by the fixing means and discharged out of
the photocopying machine from the outlet 12. Since the copy paper P
is charged, the electrostatic charge is removed from the copy paper
P by an AC charging means 30.
In addition to the means described above, the photocopying machine
in accordance with the present invention further includes driving
means, exposure means, feeding means, control means and so on and
the present invention is characterized by the arrangement thereof
and the assembly and disassembly thereof as will be described in
more detail hereinafter.
ORIGINAL HOLDER AND DRIVING MEANS
As shown in FIG. 3, the original holder 11 has two rollers 17 and
18. The roller 17 rides on a rail 13 extending between frames of
the housing while the roller 18 is enclosed in a channel-like
member 16 and rides on a rail 14 mounted between the frames. It is
noted that the rail 14 and the roller 18 in the channel-like member
16 are disposed below an inner frame 15 of the original holder 11.
The deviation in the transverse direction, that is to the right and
left of the original holder 11 may be prevented by the roller 18
which has a configuration of a drum as shown in FIG. 3 while the
vertical deviation may be prevented by the combination of a roller
vertically movably fixed to the channel-like member 16 and made in
contact with the undersurface of the rail 14 under the force of a
spring 20 loaded between the lower roller 19 and the upper roller
18. A transparent plate 21 such as a glass plate is mounted on the
inner frame 15 of the original holder 11 and a pressure plate 22
for pressing the original against the transparent plate 21 is
provided.
Still referring to FIG. 3, a shaft 27 of the sensitive drum 1
extending through bearings 23 of end plates 1.sub.1 and 1.sub.2 is
supported by supporting plates 25.sub.1 and 25.sub.2 and retained
by retaining members 26.sub.1 and 26.sub.2. Stays 24 are fixed to
the supporting plates 26.sub.1 and 26.sub.2 which in turn are fixed
to side plates 31.sub.1 and 31.sub.2 fixed to the housing. A
driving gear 30 is mounted on a boss of the sensitive drum 1. Thus,
the sensitive drum unit is constituted.
A drive gear G.sub.4 for driving the sensitive drum unit is
provided with a control member CAM 1 which is associated with a
switch MS-1 mounted upon the side plate 31.sub.2 for controlling
the original holder, a counter and the toner supply.
Ridges 33 are formed on the supporting plates 25.sub.1 and 25.sub.2
while their mating grooves 32 are formed in the side plates
31.sub.1 and 31.sub.2 as shown in FIGS. 4 and 6 so that the drum
unit may be easily, rapidly and vertically mounted on or removed
out of the side plates 31.sub.1 and 31.sub.2. The drum unit may be
securely held in position by means of setscrews 34.
The sensitive drum 1 is driven by an electric motor MT through a
gear G.sub.1, an idler G.sub.2 and the drive gear G.sub.4 carried
by the drum shaft 27. The sensitive drum 1 is always rotated in a
predetermined direction in operation.
The original holder 11 is moved in the direction indicated by the
arrow a in FIG. 2 when the exposure is made, and upon completion of
the exposure the original holder 11 is reversed in the direction of
the arrow b to the initial position. For this purpose, two belts or
wires 35 and 36 are wrapped around a guide pulley R and a drive
pulley PL in the opposite directions. One ends of the belts or
wires 35 and 36 are fixed to the channel-like member 16 while the
other ends to the drive pulley PL. In order to make one
reciprocation of the original holder in one cycle operation, two
clutches C-1 and C-2 are provided as shown in FIG. 4.
In response to a signal from a start button, the main motor MT
starts to rotate the sensitive drum 1 through the gears G.sub.1,
G.sub.2 and G.sub.4. When the switch MS-1 is actuated by the
control member CAM-1 of the gear G.sub.4 carried by the sensitive
drum 1, the clutch C-1 is actuated so as to transmit the power from
the main motor MT to a drive gear G.sub.8 through the gears
G.sub.1, G.sub.2, clutch C-1, and a gear G.sub.3.
The drive gear G.sub.8 is carried by a shaft 37 which also carries
the pulley PL. Therefore the drive pulley 37 rotates in the
direction of the arrow C in FIG. 5, winding the wire 35 while
unwinding the wire 36. As a consequence, the original holder 11 is
moved in the direction indicated by the arrow a at a predetermined
speed, so that the original is exposed through a slit and the light
image is continuously projected upon the sensitive drum 1 through
the simultaneous exposure-charging means 5. As a consequence, an
electrostatic latent image is formed upon the sensitive drum 1
which has been previously charged by the first charging means
4.
The peripheral speed of the sensitive drum 1 relative to the speed
of the original holder 11 in the direction of the arrow a is
predetermined. Upon completion of the going stroke of the original
holder 11, a stroke cam CAM-2 (See FIG. 4) mounted upon the drive
gear G.sub.8 actuates a microswitch MS-3 fixed upon the housing so
that the clutch C-1 is disengaged while the clutch C-2 is engaged.
Whereas the sensitive drum 1 rotates in the same direction, the
original holder 11 is returned to its initial position in the
direction indicated by the arrow b by the gear train of G.sub.1,
G.sub.2, G.sub.4, G.sub.5, the clutch C-2, G.sub.7 and G.sub.8. In
this case, the original holder 11 may be returned quickly when the
number of teeth of the gear G.sub.7 which is in mesh with the gear
G.sub.8 used in the return stroke of the original holder 11 is less
than that of the gear used in the going stroke. Thie quick return
stroke permits the high speed copying operation.
When the original holder 11 returns to its initial position, the
stroke cam CAM-3 of the drive gear G.sub.8 actuates a microswitch
MS-2 (See FIG. 4) so that the main motor MT is temporarily applied
with brake so as to stop the original holder 11. A short time after
the original holder 11 has been stopped, the clutch C-2 is
disengaged so that the original holder 11 is completely
disconnected from the main motor MT so that the original holder 11
may be held in its initial position. Simultaneously the sensitive
drum 1 is also stopped. The above described two-step operation of
first stopping the original holder 11 and then disconnecting it
from its driving means is employed to absorb the inertia of the
original holder in its return stroke.
EXPOSURE MEANS
As shown in FIGS. 2 and 7, an illumination system 40 includes a
light source such as fluorescent lamps 41 for illuminating the
original, shielding plates 42 and cooling means such as a fan (not
shown) which is used for cooling the lamps 41 so as to prevent the
decrease of its illumination efficiency.
The cooling air from the fan is directed in the longitudinal
direction of a space defined by the original holder 11, the
shielding plates 42 and a black box 43 so that the fluorescent
lamps 41 may be cooled along their entire lengths. When the
fluorescent lamps 41 are turned on for exposure, a current twice
the rated current is supplied to increase the luminous intensity.
However, when no exposure is made, the lamps 41 are normally turned
on by the rated current so that there may be no warming-up time and
that its service life may be increased.
Light reflected by the original passes through a transparent plate
45 retained in position by a retaining member 44 for preventing the
dust or the like from entering the black box 43 and is re-directed
by a first reflecting mirror 46 inclined at 45.degree. relative to
the horizontal line toward an in-mirror type lens 47. The in-mirror
type lens 47 has such a construction that the conventional lens is
divided into two parts along its symmetrical axis and a mirror 48
is disposed at the center so that light reflected by the second
mirror 48 may pass through the lens 47 and a transparent plate 49
for preventing the dust or the like from entering the black box 43
and may be projected upon the sensitive drum 1 through an opening
of the simultaneous-exposure-charging means 5. A conducting
transparent plate such as NESA glass may be used as the dust-proof
transparent plate 49 so that the charging efficiency of the
simultaneous exposure-charging means 5 may be improved.
As shown in FIG. 2, a reflector 50 for the lamp 41 is partly cut
away so that the intensity of light from a portion of the lamp 41
having no reflector may be reduced, whereby the original may be
uniformly illuminated regardless of the reduction in light quantity
or fall-off of luminance in the peripheral portion of the lens 47.
As shown in FIG. 7, a slit 51 is formed through the shielding plate
42 so that light from the light source may be directed toward the
sensitive drum 1 by a guide plate 52 for effecting the pre-exposure
before the sensitive drum 1 reaches the first charging means 5. The
effect of the pre-exposure is that a better image may be always
produced under the constant conditions as is disclosed in detail in
U.S. SN. 57732 filed July 23, 1970.
The light guide plate 52, the first charging means 4 and the
simultaneous exposure-charging means 5 are formed as a unitary
construction with the side plates 53.sub.1 and 53.sub.2 which are
provided with guides 54 (See FIG. 7) for vertically mounting or
dismounting the unit. Therefore, the inspection and maintenance of
the first charging means 4 and the simultaneous exposure-charging
means 5 are much facilitated. This arrangement also facilitate the
replacement of the sensitive drum 1.
The light source 41 is made into a unitary construction with the
shielding plate 42 so as to facilitate the replacement and cleaning
thereof since the unit may be drawn toward an operator.
ELECTROPHOTOGRAPHIC PROCESSING MEANS
In response to the signal from the start switch the sensitive drum
1 starts to rotate. Around the sensitive drum are disposed the
first charging means 4 and the simultaneous exposure-charging means
5 where the sensitive drum 1 rotating in synchronism with the
original holder 11 is simultaneously exposed and charged so that an
electrostatic latent image is produced. By means of the
whole-surface exposure means 6 the sensitive drum 1 is uniformly
illuminated so as to form a high contrast latent image. Prior to
the first charging, the pre-exposure may be effected by light
passing through the slit 51.
As shown in FIG. 8, the developing means 8 includes a pair of side
plates 101 and a bottom plate which defines a box or container, in
which are housed two magnet brushes 102 and 103 rotatably supported
between the side walls 101, two doctor blades 104 and 105 and
mixing screws 106 and 107.
Each of the magnet brushes 102 and 103 comprises a non-magnetic
shaft and a magnet roll in which the north and south poles are
alternatively arrayed. It should be noted that the magnet brushes
102 and 103 are so arranged that the opposite poles may oppose to
each other as shown in FIG. 8.
Developing agent 110 consists of toner and finely divided iron
powder (carrier), which may be mixed sufficiently by the mixing
screws 106 and 107 while moved toward the magnet brushes. The
developing agent is attracted by the magnet brushes 102 and 103.
The developing agent is supplied by a predetermined quantity from a
hopper 108 shown in FIG. 9. The developing agent 110 is dropped
onto one end of the mixing screw 106 through an opening 109 of the
hopper 110 and an opening 111 of the developing means. The mixing
screw 106 mixes the condensed developing agent 114 supplied from
the hopper 108 with the developing agent 110 and feeds the mixture
toward the other mixing screw 107. A partition wall 112 is disposed
between the mixing screws 106 and 107 so that the developing agent
110 is fed into the developing means 7 only by the mixing screw
106.
A port 113 is formed through the partition wall 112 for
communication between the chambers of the mixing screws 106 and 107
so that the developing agent 110 fed into the developing means 7 by
the mixing screw 106 is fed toward the mixing screw 107 through the
port 103 and then toward the developing means by the mixing screw
107. The developing agent 110 is attracted by the first magnet
roller 102 and then transferred to the second roller 103 by the
magnetic force so that the developing agent uniformly adheres to
the second roller 103 to form the so-called magnet brush.
When the surface of the sensitive drum 1 upon which is formed the
electrostatic latent image is rubbed by the leading edges of the
magnet brush at which the magnetic forces are generally weak, the
leading edges are attracted by the sensitive drum 1 and cut off by
the electrostatic force so that the image is fogged or
deteriorated. To prevent the magnet brushes from impairing the
image, the blades 104 and 105 are provided so as to cut the magnet
brush to a predetermined height. The magnet rollers 102 and 103 are
rotated in the directions indicated by the arrows in FIG. 8 and the
latent image is developed by the magnet brush formed in the space
between the sensitive drum 1 and the pair of magnet rollers 102 and
103. Thus, the latent image is developed into the visible toner
image.
The developing means 7 may be mounted in the housing and removed
therefrom through guides 115 fixed to the housing and guides 116
fixed to the main body.
Conduits 117 and 118 surround the developing means 7, open at 119
and 120 toward the sensitive drum 1 as dust collecting openings and
are connected to dust collecting means 130. The scattered
developing agent may be collected through the openings 119 and 120
and the conduits 117 and 118 into a bag in the dust collecting
means 130 so that the interior of the photocopying machine will not
be contaminated by the developing agent scattered by the magnet
rollers 102 and 103. The dust collecting means 130 and the
developing means 7 are provided as separate units so that there is
an advantage that the handling of the developing means 7 may be
much facilitated.
As shown in FIG. 10, the hopper 108 has its left side fixed to the
main body by means of a hinge 108.sub.1 so that it may be opened
when the developing means 7 is to be removed or when the developing
agent is to be supplied into the hopper 108. Since the hopper 108
and the developing means 7 are provided as separate units, the
handling of the developing means 7 and the supply of the developing
agent into the hopper 108 may be much facilitated.
In the lower portion of the hopper 108 is desposed a developing
agent feed roller 132 driven by a driving means 133 comprising a
plunger magnet 134 actuable in response to a signal from a switch
MS-1 to be actuated by the control member CAM-1 on the drive gear
G.sub.4, a means 135 such as a ratchet mechanism for converting the
reciprocation of the plunger into the rotary motion and one-way
clutch free wheels 136 and 137 carried by the feed roll 132.
Therefore, the feed roll 132 is rotated when the plunger magnet 134
is energized so that a predetermined quantity of the developing
agent 114 may be dropped into the developing means 7 through the
opening 109.
When the supply of the developing agent to the developing means 7
by the automatic feeding device is not sufficient because a large
number of copies must be reproduced from an original, a crank arm
139 disposed outside of the hopper 108 (See FIG. 9) is rotated so
as to manually drive the feed roller 132 through a belt 138 and the
one-way clutch 137 to feed a desired amount of developing agent. It
is possible to use a developing agent feeding means of the type
having a feed opening, a cover of this opening and a manual lever
to open and close this cover.
Next referring to FIG. 12, the function of the mixing screws 106
and 107 will be described. The developing means in accordance with
the present invention has a function of developing a visible image
by attracting the developing agent by the magnet rolls so as to
form the magnet brush and rubbing the latent image on the sensitive
drum by the magnet brush to adhere the toner to the latent image.
Therefore, it is apparent that the ratio of the carrier to the
toner is reduced as one copy is reproduced. It is therefore
important in an automatic photo-copying machine to supply a
predetermined quantity of developing agent by always supplying the
toner and mixing it sufficiently so that the tone of the developed
image may be maintained constant on every copy paper.
In the instant embodiment of the present invention, the pair of
screws 106 and 107 are disposed on both sides of the partition
walls 112 in such a way that the developing agent may be circulated
along the axes of the screws 106 and 107. In order that the
developing agent may be transferred from one screws to another at
the ends of the screws through the communication ports such as 113
the directions of the screws are reversed as shown at 106.sub.2 and
107.sub.2. In addition the flow rate of the developing agent throug
at least one port is made smaller than the feed by the feed screw.
The developing agent including the toner supplied is moved in the
direction indicated by the arrow by the feed screws 106 while the
developing agent is mixed and is reversed at 106.sub.2 so that the
developing agent is accumulated at 106.sub.2. The accumulated
developing agent is mixed and moved toward the developing means 7
in a predetermined quantity through the port 113. The developing
agent is moved by the return screw 107 and attracted by the magnet
roller 102. In this case, the excess developing agent is removed by
the blade 104. The developing agent upon the magnet roller 102 is
then transferred to the magnet roller 103 where the developing
agent forms the magnet brush which develops the latent image upon
the sensitive drum 1. The excess developing agent on the magnet
brush of the magnet roller 103 is also removed by the blade 105 and
transported in the direction indicated by the arrow by the return
screw 107. In this case a portion of the developing agent removed
by the blade 105 from the magnetic roller 103 may be attracted by
the magnet roller 102 again. The developing agent is circulated in
the developing means in the manner described above.
The developing agent transported by the return screw 107 toward to
its end is reversed at 107.sub.2 and redirected into the feeding
section 110. Thereafter the developing agent is circulated in the
manner described above.
The arrangement described above for circulating the developing
agent has the following advantages:
1. The quantity of the circulating developing agent may be
maintained constant because the circulating developing agent may be
maintained constant because the circulation is controlled by the
port 113 formed through the partition plate 112 so that
a. the quantity of developing agent adhered to the magnet rollers
102 and 103 and the quantity of the developing agent to be
exchanged may be maintained constant, whereby the density of the
image may be statibilized or maintained uniform;
b. the quantity of developing agent removed by the blades 104 and
105 may be maintained constant, which means that the loads on the
blades are constant, whereby the selection of a motor is simple;
and
c. the quantity of circulating developing agent may be maintained
at minimum, which means that the fatigue of developing agent (the
decrease in developing ability) may be minimized.
2. The toner supplied from the hopper or the like may be
immediately and sufficiently mixed with the developing agent
discharged out of the developing means 7.
3. The developing agent transported by the feed screw 106 toward
the port 103 is sufficiently mixed at 106.sub.2 (the reversed
portion) before a predetermined quantity of developing agent is fed
toward the screw 107 through the port 113 so that even though the
concentration of the toner may be rapid, no excess toner
concentration will occur.
4. Both of the screws 106 and 107 may be of the same construction
so that they may be provided in a simple manner and at less
cost.
The diameter of the opening of the port 113 may be adjusted by
means of an adjusting plate or the like so that the effective
opening of the port 113 may be adjusted to permit the rather faster
consumption of toner in case of copying a picture or the like and
then may be reduced in case of copying an original bearing only
characters or the like, which requires less consumption of
toner.
FIGS. 13-19 illustrate another embodiment of developing agent feed
means in accordance with the present invention. As shown in FIG.
13, a hopper 140 has its left side hinged to the main body by a
hinge 142 in such a way that the hopper may be opened when the
developing means is to be removed out of the photocopying machine
or when the developing agent or toner is to be supplied into the
hopper 140. This arrangement facilitates the handling of the
developing means and the supply of the developing agent into the
hopper 140.
A toothed wheel 152 having square or crown-shaped teeth 153 is
rotatably disposed inside the hopper 140 and is in mesh with a feed
screw 143 so that the toothed wheel 152 may be intermittently
rotated as the feed screw 143 rotates. At least one mixing blade
154 is mounted upon the toothed wheel 152 so as to mix the supplied
developing agent 170 in the hopper 140. This arrangement serves to
prevent the bridging phenomenon of developing agent, the
arrangement being very advantageous.
Since the hopper 140 is hinged as described above, its discharge
opening 149 must be closed unless it co-incides with a feed opening
169 of the developing means. The manual operation is cumbersome and
tends to cause the contamination of the interior of the
photocopying machine. It is therefore preferable that the discharge
opening 149 may be automatically opened and closed.
As shown in FIGS. 13, 15 and 16, the flange 156 of a cover 155 is
fitted into a guide groove 157 in the discharge opening 149 and is
biased by a spring 158. A discharge opening 159 mating with the
discharge opening 149 of the hopper 140 is provided in the cover
155. When the hopper 140 is opened to the left in order to supply
the developing agent, the cover 155 is positioned as shown in FIG.
15 under the bias of the spring 158 so that the discharge opening
149 of the hopper 140 is closed by the cover 155 at its portion not
provided with the discharge opening 159. As a consequence no
developing agent is discharged out of the hopper 140 through the
discharge opening 149.
When the hopper 140 is returned to its operative position, the
cover 155 is moved to a position as shown in FIG. 16 against the
spring 158 by a side plate 160 of the main body of the photocopying
machine so that the discharge opening 149 coincides with the
discharge opening 159 of the cover 155. Therefore, the developing
agent in the hopper 140 may be dropped into the opening 169 of the
developing means by a feed roller 143.
The quantity of condensed developing agent to be supplied is varied
depending upon the originals. That is in case of an original having
large black areas or portions a large quantity of developing agent
is supplied. On the other hand in case of an original having less
black portions a less quantity of developing agent is supplied.
This is true when the sizes of copy papers are varied. The
automatic developing agent feeding means is normally adjusted so as
to supply a less quantity and if required a large quantity of
developing agent may be supplied by the manual operation in the
manner described above.
The quantity of developing agent to be supplied may be
automatically varied if the feed by the feed roller 143 is varied.
This arrangement is illustrated in FIGS. 18 and 19, in which the
angular displacement of a rotary solenoid 143 is varied so as to
control the feed by the feed roller 143. FIG. 17 shows that the
angular displacement of a crank 161 by the rotary solenoid 145 is
controlled by means of a knob 162, belt 163, a pulley 166, a
threaded rod 167 and a stopper 164. In the arrangement shown in
FIG. 18, the angular displacement of the crank 161 is controlled by
means of a stopper cam 165.
COPY PAPER FEEDING
As shown in FIGS. 20 and 21 copy paper is fed and transported by
feeding means 55 and transporting means 56.
In response to the signal from the switch MS-1 actuated by the
control member CAM-1 mounted upon the drive gear G.sub.4, a feed
roller 57 starts to rotate to feed a copy paper P one by one into
the transporting means 56, which includes a first and second pairs
of feed rollers 58 and 59. The first pair of rollers 58 are rotated
intermittently in response to the signal from the control member
CAM-1 on the drive gear G.sub.4 so as to control the timing of the
transportation of the copy paper P so that the toner image
developed upon the sensitive drum 1 may be transferred onto a
predetermined portion of the copy paper P by the transfer means 9.
In this case, it is noted that the first pair of feed rollers 58
also serves to align the leading side edge of the copy paper P in
the transverse direction. The second pair of rollers 59 are
normally rotating for transporting the copy paper P to the image
transfer means 9.
The leading edge of the copy paper P which is fed one by one by
feed rollers 57 in the feeding means 55 is stopped by the first
pair of rollers 58 so that the copy paper P is bowed as indicated
by the two dot lines P' in FIG. 20. Therefore the leading side edge
of the copy paper P is aligned in the direction of the axes of the
first pair of rollers 58. In response to the signal from the
control member CAM-2, the first pair of rollers 58 start to rotate
so as to transport it toward the second pair of rollers 59, which
in turn transports the copy paper P toward the transfer means 9
where the copy paper 1 may be pressed against the sensitive drum 1
so that the toner image upon the sensitive drum 1 may be
transferred onto the copy paper P.
A means for controlling the developing means consisting of a light
source 60, a mirrors 61 and 62 and a photoelectric effect element
63 is disposed in the path of the copy paper so that the passage of
the copy paper may be sensed and that in response to the detection
the developing means 7 is controlled. When no copy paper P is fed
so that a switch MS-9 is not actuated, the developing means 7 is
not activated so that the electrostatic latent image upon the
sensitive drum 1 is not developed and consequently the transfer
means 9 in contact with the sensitive drum 1 will not be
contaminated. In addition, no load is applied to cleaning rollers
in the cleaning means 10.
Referring to FIGS. 20 and 21, the feeding means 55 will be
described in more detail hereinafter.
A copy paper stand 199 may be readily mounted into and removed out
of the main body of the photocopying machine through guide rails 64
and 65. L-shaped guides 200 and 201 are mounted upon the copy paper
stand 199 on the right and left sides thereof respectively.
Depending upon the size of the copy paper to be used, the right
guide 201 may be displaced in the transverse direction of the copy
paper stand 199 while the left side guide 200 is held stationary.
Pads 205 are disposed in the notches in the L-shaped guides 200 and
201 and biased inwardly by springs 204 so as to press against the
side edges of the copy papers P. By this arrangement, the undesired
resistance to the copy paper may be avoided and the one-by-one
separation of copy papers may be facilitated.
Separating levers 207 and 208 are tiltably fixed to the outside
surfaces of the guides 200 and 201 by means of pivots 206 and at
the leading or free end of each of the separating levers 207 and
208 is provided a separating claw having downwardly extending
projection 209 (See FIG. 20) for engagement with the corner of the
copy paper P and a horizontally extending projection 210 for
pressing the corner of the copy paper from the above. The copy
paper P fed by the feed roller 57 is made in engagement with the
downwardly extending projections 209 so that the copy paper P is
prevented from being advanced, but the center portion of the copy
paper P is permitted to advanced. As a consequence the buckling of
the copy paper P occurs so that the uppermost copy paper is
permitted to be disengaged from the pawls and transported into the
feeding means 56.
For placing the stack of copy paper P upon the feed stand 119, a
set button 67 is depressed (See FIG. 20) so as to rotate an
integral arm 66 in the clockwise direction, thereby raising the
separating lever 207 through its downwardly extending projection
207.sub.1. As a consequence there is provided a clearance or space
between the separating pawls 210 and the stand 199. After the stack
of copy paper being placed upon the feed stand 199, the set button
67 is released so as to permit the rotation of the separating
levers 207 and 208 by their own weights about their pivots 206,
whereby the horizontally extending projections 210 of the
separating pawls are placed over the uppermost copy paper.
When the copy paper feed stand 199 is mounted on or removed away
from the main body of the photocopying machine, the feed roller 57
may be lifted by rotating a knob 68 which is connected to the feed
roller 57 through a wire or the like 69. This arrangement
facilitates the mounting or removal of the copy paper feed stand
199.
A plurality of feed rollers 57 are carried by a shaft 70 which in
turn is supported by arms 72. The arms 72 are pivotally carried by
a drive shaft 71, which drives the rollers 57 through sprockets 73
and 74 and a chain 77.
The first pair of feed rollers 58 are coupled indirectly through a
sprocket wheel 76 and a chain 77 so as to be rotated in response to
the actuation of an electromagnet clutch C-3 (See FIG. 21). The
sprocket wheel 76 is normally rotated. The chain 77 also rotates a
sprocket wheel 78 carried by a shaft 78.sub.1. A gear G.sub.9
carried by the other end of the shaft 78.sub.1 is connected with or
disconnected from a gear G.sub.10 carried by the drive shaft 71
through a gear clutch mechanism 79, which comprises an arm which
rotates about a shaft 80, and gears G.sub.11 - G.sub.13 which are
driven by the normally rotating gear G.sub.9 carried by the arm 81.
Normally the arm 81 is biased by a spring 82 so that the gear
G.sub.13 may not engage with the gear G.sub.10.
The lower end of the arm 81 is connected to a plunger magnet PL
through a cushion member 83. In response to the signal generated
upon depression of the start button, the gear G.sub.4 of the
sensitive drum 1 rotates and when the control member CAM-1 acutates
the switch MS-1, the plunger magnet PL (See FIG. 21) is energized
so as to rotate the arm 81 in the clockwise direction. The gear
G.sub.13 meshes with the gear G.sub.10 so that the feed rollers 57
are rotated, whereby the copy paper P is moved toward the first
pair of rollers 58.
When the switch MS-4 is actuated by the control member CAM-4, the
clutch is engaged so as to drive the first pair of feed rollers 58.
Simultaneously, the plunger magnet PL is de-energized so that the
clutch mechanism 79 is disconnected. As a consequence, the positive
rotation of the feed rollers 57 is stopped but they rotate freely
as the copy paper P is advanced.
The copy paper P is further advanced toward the second pair of feed
rollers 59 through guides 85 and 86 and then into the image
transfer means 9 through guides 87 and 88. An optical path
indicated by 89, 90 and 91 is provided (See FIG. 20) through the
guides 86-88 so that when the leading edge of the copy paper P
passes through the optical path 91, the developing means is
activated. The sensing position 91 which is provided by optical
elements 62 and 63 is so positioned that the developing means may
be activated before the latent image formed upon the sensitive drum
1 enters the developing means. When the optical path 89 is
interrupted by the leading edge of the copy paper being
transported, no signal is generated because the optical path 91 has
been already interrupted.
When the trailing edge of the copy paper P has passed the optical
path 91, no signal is generated because the optical path 89 is
still interrupted. However, when the trailing edge of the copy
paper P has moved past the optical path 89, the control means for
the developing means is so activated as to stop the developing
means.
Because of the two sensing positions or optical paths 91 and 89,
the development of the latent image may be started earlier and
stopped later so that a portion or area on the sensitive drum 1
larger than that of the latent image may be developed. In other
words, the time required for the copy paper P to pass over a
distance between the two optical paths 91 and 86 corresponds to a
developing time.
The second pair of feed rollers 59 (59.sub.2) are normally
connected to the main drive motor MT through the chain 77 so as to
be normally rotated. When the second pair of feed rollers 59 should
stop by failure of operation while the copy paper P is still
passing through the nip between the pair of feed rollers 59, it is
extremely difficult to remove the jammed copy paper out of the
transporting means 56 especially when the drive motor MT is
rotating, that is without stopping the second pair of feed rollers
59. To facilitate the removal of the jammed copy paper, the feed
roller 59.sub.2 and the guide 86 are mounted upon an auxiliary side
plate 94 rotatably fixed by a pivot 93 to the side plate 92 of the
main body of the transporting means 56. Therefore, the auxiliary
side plate 94 may be opened as shown in FIG. 20 so that the feed
roller 59.sub.2 and the guide 86 may be removed out of the path of
the copy paper. As a consequence, the maintenance of the
photocopying machine may be much facilitated.
Another embodiment of a means for controlling the developing means
in accordance with the present invention is illustrated in FIGS. 22
and 23. In the path of the copy paper there are disposed two
microswitches 171 and 172 in such a way that they may be actuated
by the copy paper P being transported. As shown in FIG 23, the two
microswitches 171 and 172 are connected in parallel with each other
and in series to the drive motor MT for driving the developing
means. S denotes a power source. The microswitch 171 is located in
such a position where the leading edge of the copy paper P actuates
the microswitch 171 when the leading edge A of the latent image
upon the sensitive drum 1 reaches the development start position B
of the developing means 6 or slightly before the point B. The
second microswitch 172 is spaced apart from and in front of the
first microswitch 171 by a distance l which is equal to or slightly
longer than the effective developing length of the developing means
6.
When the leading edge of the copy paper P which is transported in
synchronism with the rotation of the sensitive drum 1 actuates the
first microswitch 171 so as to make it, the drive motor MT is
started so as to start the developing operation. Even when the
leading edge of the copy paper P activates the switch 172, no
signal is generated because the microswitch 171 has been already
closed. In a similar manner even when the microswitch 171 is opened
there is no change because the microswitch 172 is still closed.
Only when the trailing edge of the copy paper P deactivates or
opens the microswitch 172, the circuit of the motor MT is opened so
that the developing means is stopped. In other words, the latent
image on the sensitive drum 1 is developed from its leading edge A
by a length corresponding to the length l over which the copy paper
P is transported. The length of an area of the sensitive drum
developed during a time interval between the time the first
microswitch 171 is closed and the time the second microswitch 172
is opened is equal to the length of the copy paper P.
IMAGE TRANSFER MEANS AND SEPARATING MEANS
The copy paper transported from the copy paper feeding means 55 by
the first and second feed rollers 58 and 59 is pressed against the
toner image upon the sensitive drum 1 by the image transfer roller,
which is preferably made of conducting material.
The separating means is disposed at or in the vicinity of the
transfer means so as to separate the copy paper from the sensitive
drum after image transfer.
A separating band 250 is interposed between the copy paper P and
the sensitive drum 1 along the arc of the drum as shown in FIG. 20.
For example the band 250 is made of a polyester film of 50.mu. in
thickness and is disposed along at least one side edge of the copy
paper so as to overlap about 10 mm with the copy paper. A spring
251 is connected to one end of the separating band 250 so as to
tension it. A separating roller 252 disposed immediately after the
image transfer means 9 rotates at a peripheral speed faster than
that of the sensitive drum 1, and the separating band 250 is
wrapped around an arc less than 180.degree. of the separating
roller 252 and extended in the direction away from the sensitive
drum 1. After the image transfer, the side edge of the copy paper P
is separated from the sensitive drum 1 by the separating band 250
and transferred upon a belt 253 so that the copy paper P may be
positively moved away from the sensitive drum 1 and transported
into the fixing means by the conveyor belt 253.
FIXING MEANS
As shown in FIGS. 24, 25 and 26, the fixing means comprises an
upper and lower fixing chambers 300 and 301. The upper fixing
chamber 300 is rotatably fixed to the lower fixing chamber 301 by a
pivot 302 so that the upper chamber 300 may be opened. The upper
chamber 300 may be retained in opened position by means of a
supporting arm 303. This arrangement facilitates the removal of the
jammed copy paper from the fixing means.
The upper fixing chambers 300 comprises an upper fixing means 305
having infrared lamps or heaters 304, sprockets 306 disposed around
the upper fixing means 305 and a chain 307 wrapped around the
sprockets 306 so that the contact of the copy paper with the lamps
or heaters 304 may be prevented. The upper fixing means 305 is so
arranged as to be drawn from the upper fixing chamber 300 toward
the operator along guides 320 and 321.
The lower fixing chamber 301 comprises a lower fixing means 313
having an infrared lamp or heater 308, sprocket wheels 309, chain
belt rollers 310, a chain 311 and a chain belt 312 for transporting
the copy paper through the fixing means. The lower fixing means 313
may be also removed out of the lower fixing chamber 301 toward the
operator along guides.
Since the fixing means is divided into the two sections as
described above, the maintenance and repair may be much
facilitated.
A guide plate or baffle plate 314 (See FIG. 24) is disposed in the
upper portion of the upper fixing chamber 300 so that the heated
air in the upper chamber 300 may be directed along the baffle plate
314 by a fan 315 so as to be discharged out of the fixing means.
Therefore the overheating of the fixing means may be prevented. It
is noted that the baffle plate 314 is disposed in such a way that
the side edge on the side of the fan 315 of the baffle plate may be
located higher than the opposite side edge as shown in FIG. 24.
CLEANING MEANS
Cleaning rollers 506 and 507 are pressed against the sensitive drum
1 and rotated in the direction opposite to that of the sensitive
drum 1 (FIGS. 27 and 28). Each cleaning roller comprises a roller
502 and 503 made of an elastic material and carried by a shaft 500
or 501 and a cleaning cloth 504 and 505 wrapped around the outer
surface of the roller 502 and 503, respectively.
Cleaning means comprises a first and second cleaning chambers 509
and 510 separated by a partition wall 508. The first cleaning
chamber 509 houses the first cleaning roller 506, a brush roller
513 and a screw conveyor 515 for transporting the toner brushed off
from the first cleaning roller 506 by the brush roller 513 toward a
toner receiving container 514. The brush roller 513 comprises a
shaft 511 and brushes 512 secured thereto in spiral or radial form.
The brushes 512 contact with the cleaning roller 506 so as to
scrape off the toner.
An upright beating plate 516 disposed transversely of the first
cleaning chamber 509 is for engagement with the brush 512 of the
brush roller 513 to drop the toner caught between the brushes. The
toner dropped is directed by a guide plate 517 toward the screw
conveyor 515.
At the front entrance of the first cleaning chamber 509 is disposed
a roller 518 which is spaced apart from the sensitive drum 1 by a
predetermined distance and rotated in a direction indicated by the
arrow for preventing the toner from being dropped off into the
portion other than the cleaning means. The spacing between the
roller 518 and the sensitive drum 1 may be provided by
spacer-bearings 519 which rotate freely in contact with the
sensitive drum 1.
The second cleaning roller 507 in the second cleaning chamber 510
serves to remove the toner on the sensitive drum 1 which has not
wiped off by the first cleaning roller 506. The second cleaning
chamber 510 houses the second cleaning roller 507, a brush roller
522 similar to the brush roller 513 in the first cleaning chamber
509, and an upright beating plate 523 similar to the upright
beating plate 516 in the first cleaning chamber for removing the
toner from the brush roller 522. The seond cleaning chamber 510 is
provided with a suction port 524 for sucking the toner which is
scattered like mist. A suction means (not shown) is disposed in the
lower portion of the photocopying machine and contains a dust
collection bag into which is collected the toner. The toner whose
particle size is larger is dropped through a slit 525 between the
partition wall 508 and the housing of the cleaning means toward the
screw conveyor 515 in the first cleaning chamber 509. The fixing
means is rotatably fixed to the main body for the photocopying
machine by a shaft 526 and is retained in position by means of a
spring-loaded hook 527 which is hooked with the stay 24 of the
sensitive drum unit, so that the both of the cleaning rollers 506
and 507 may be pressed against the sensitive drum 1 with a suitable
pressure. When the sensitive drum 1 is removed or when the cleaning
rollers are to be replaced, the cleaning means may be moved away
from the sensitive drum 1 in the counterclockwise direction.
Another embodiment of the cleaning means in accordance with the
present invention is illustrated in FIGS. 29 through 34. Two
cleaning rollers 531 and 532 are disposed in parallel with each
other, pressed against the sensitive drum 1 and rotated in the
direction opposite to that of the sensitive drum 1. The peripheral
surfaces of the cleaning rollers 531 and 532 are applied with for
example suede-finished cloth.
Brush rollers 535 and 536 are rotated in the direction opposite to
that of the cleaning rollers 531 and 532 in contact therewith.
Upright beating members 537 and 538 are disposed so as to engage
with the leading edges of brushes of the brush rollers 535 and 536
so as to remove the toner. The toner scattered in the cleaning
means may be collected through a suction port 539. The air flow
into the suction port may be less than 0.8m.sup.3 /minute. A baffle
plate 540 is disposed so as to prevent the contamination of the
cleaning roller 531 by the toner dropped from the cleaning roller
532. The baffle plate 540 has a downwardly extending baffle plate
540.sub.1 for directing the toner scattered in an angular range
defined by angles of 20.degree. above and below the line X-Y toward
a screw conveyor 543. The toner scattered may be directed toward
the suction port 539 through an opening 540.sub.2 formed in the
baffle plate 540. A partition wall 541 is provided for preventing
the scattered toner from reaching a sheet 552. Another baffle plate
542 is provided so as to direct downwardly the toner scattered in
an angular range defined by the angles of 20.degree. above and
below the line X-Y from the brushes 536 by the beating member 538
and to prevent the scattering of the toner within the cleaning
means. The screw or spiral conveyor 543 serves to transport the
toner dropped thereupon to a toner collection box 553. The above
parts 531-543 are disposed within a housing 544 and spaced apart
from each other by a suitable distance. The housing 544 is
rotatably fixed by a pivot 545 so that the housing may be moved
away from the sensitive drum 1. A hook 547 loaded with a spring 546
engages with the stay 548 of the main body of the photocopying
machine so as to retain the cleaning means in operative position
where the cleaning rollers 532 are pressed against the sensitive
drum 1. The contact pressure of the cleaning rollers 531 and 532
may be adjusted by the spring 546. A cover 549 for the cleaning
means is fixed to the housing 544 by setscrews 551. The sheet 552
is made in contact with the sensitive drum 1 at an angle about
15.degree. in such a way that the sheet 552 will not remove the
toner upon the sensitive drum 1. The sheet 552 is made of a soft
material such as polyester film 150 microns in thickness and serves
to prevent the toner from dropping from the cleaning means into the
space between the sensitive drum 1 and the housing 544. The toner
impinged upon the sheet 552 is directed toward the screw conveyor
543. An air inlet window 558 is provided above the roller 532.
The toner T remained on the surface of the sensitive drum 1 is
almost wiped off by the first cleaning roller 531 and the toner T'
still remained on the sensitive drum 1 is completely removed by the
second cleaning roller 532. The toner attached to the cleaning
roller 531 and 532 is removed by the brush rollers 535 and 536 so
that the clean surfaces of the cleaning rollers 531 and 532 may
contact with the sensitive drum 1. The toner-contaminated brush
rollers 535 and 536 are cleaned by the beating members 537 and 538
so that the clean brushed may contact with the cleaning rollers 531
and 532.
The toner removed from the cleaning roller 531 and dropped
naturally may be directed by the sheet 552 and the horizontal
portion of the partition wall 541 toward the screw conveyor 543.
The toner attached to the cleaning roller 531 is removed by the
brush roller 535 and dropped upon the screw conveyor 543. The toner
removed by the cleaning roller 532 and the brush roller 536 is
directed toward the screw conveyor 543 along the baffle plate or
partition wall 540. The toner removed by the beating members 537
and 538 from the brush rollers 545 and 537 is also dropped upon the
screw conveyor 543. The toner dropped upon the screw conveyor 543
is transported to the toner collection box 553. The toner scattered
when the beating member 538 strikes the brush roller 536 is
directed downward by the baffle plate 542 and is collected in a
collecting means (not shown) disposed outside of the cleaning
housing 544 through the suction port 539. Thus the interior of the
housing 544 of the cleaning means may be always kept clean.
When the special cleaning of the cleaning means is required or when
the brushed 535 and 536 are to be replaced, the setscrews 551 are
unscrewed so as to open the cover 549. The housing 544 of the
cleaning means may be rotated about the pivot 545 for inspection
and maintenance of the sensitive drum 1.
For example the hardness of the cleaning rollers 531 and 532 is
20.degree.; the diameters are 50 and 60 mm respectively; the
rotating speed is about one-fifth to one-half rpm; and the contact
pressure is about 20 to 30 kg per 270 mm.
As shown in FIGS. 30 and 31, nylon brushes 554 of 200 microns in
diameter and 10 mm in length are fixed in holes 556 formed in
spiral forms with a pitch of 5 mm and a lead of 60 mm.
Alternatively the brushed 544 may be fixed by a U-shaped metal
frame 557 as shown in FIG. 32-(A) and the leg portion of the metal
frame are cauked or pressed toward each other so that the brushes
554 may be firmly held in position as shown in FIG. 32-(B). Next
the brush is wrapped around a shaft. A further method for providing
a brush roller is to secure the brushes 554 into the spiral grooves
formed in a synthetic resin shaft 555. Preferably the brush rollers
535 and 536 intersect the cleaning rollers 531 and 532 about 2 mm
and rotate at about 60 rpm (in case of the outer diameters being 36
mm). If they are rotated faster, the desired cleaning effect will
be improved, but the service life of the cleaning material applied
on the surfaces of the cleaning rollers 531 and 532 will become
shorter.
It is preferable that the brush rollers 535 and 536 intersect the
beating members 537 and 538 about 2 mm. It is necessary that the
beating member will not cause any damage to the brushes. The
problem to be taken into consideration in this case is that the
toner melts and grows on the beating members 537 and 538. Thus
grown toner on the beating member tends to damage the brush, and if
removed from the beating member by the rotating brush, the grown
toner falls and accumulates in the housing of the cleaning means
and prevents the toner fallen off from the brushes and cleaning
rollers from being freely directed toward the screw conveyor. To
solve this problem, the beating members are so arranged as to
freely rotate when they are round bars. Alternatively, the surfaces
of the round bars may be applied with fluoroplastics. When the
beating members may be also in the form of plate, the melting and
growing of the toner may be reduced. When the surfaces of the
plates are coated with fluoroplastics, the problem of fusion and
growth of toner may be completely overcomed.
FIG. 25 illustrates a method for permitting the easy application of
a cleaning material such as suede-finished cloth around the outer
periphery of the cleaning roller in such a manner that the cleaning
material may be replaced in a simple manner. Since the cleaning
material is always pressed against the sensitive drum and is also
made in contact with brush roller, the wear of the cleaning
material is rapid so that the toner tends to be lodged between the
untwisted fibers. It will become difficult to remove by the brush
roller the toner lodged so that the cleaning efficiency will be
decreased. Therefore, the cleaning material should be supplied as
an expandable part and replaced as needs demand.
A cleaning material 586 is first cut into a length slightly longer
than the circumference of the roller 587 and an adhesive agent 582
such as an adhesive tape whose both surfaces are applied with an
adhesive agent is applied to the margin of about 10 - 20 mm of the
undersurface of the leading side edge so as to bond the cleaning
material upon the cleaning roller 587 as shown in FIG. 35a. Next
the cleaning roller 587 is rotated in the direction indicated by
the arrow so as to wrap the cleaning material 586 therearound. The
margin of about 10 - 20 mm at the trailing end of the cleaning
material 586 is over-lapped over and bonded to the leading side
edge as shown in FIG. 35b.
Since the cleaning roller having the cleaning material wrapped
therearound in the manner described above rotates in the direction
opposite to that of the sensitive drum and the brush roller as
shown in FIGS. 27-29 the pressures are applied to the cleaning
material in the direction of its wrapping or winding so that the
cleaning material will not be loosened in cleaning operation of
removing the toner from the sensitive drum 1.
The cleaning material 586 may be peeled off from the cleaning
roller 587 in a simple manner as shown in FIGS. 35c and 35d. It is
not necessary to replace the cleaning roller itself at all. Thus
there is provided an inexpensive cleaning roller whose maintenance
may be made by the users in a simple manner. Therefore the cleaning
rollers may be always kept clean so as to produce better quality
copy papers.
Since the cleaning roller 587 is drivingly coupled to the main
motor through a reduction gear (reduction ratio being a fraction of
a few hundred), it is impossible to manually rotate the cleaning
drum 587 when the cleaning material 586 is replaced without
disconnecting the cleaning roller from the main motor. However, it
is not preferable to provide a complex clutch mechanism for this
purpose.
To overcome this problem, the present invention provides an
arrangement that a ratchet wheel 574 is fixed by means of a pin 581
to the shaft 584 of the cleaning roller 587 outside of the side
wall 583 of the cleaning means as shown in FIGS. 36 and 37. A
ratchet wheel 573 and its bias spring 571 are fixed to a plate 570
which in turn is fixed directly or by means of screws 578 to an
adjacent drive gear. 579 indicates a snap ring.
Because of the arrangement described above, the cleaning roller may
be rotated freely in the direction indicated by the arrow in FIG.
36 when the cleaning means or unit is moved away from the sensitive
drum so that even an unskilled operator may easily replace the
cleaning material 586.
Instead of the ratchet 571 - 574, one-way clutch or the like may be
used.
CHARGING MEANS
The safety and the easy maintenance are important in a photocopying
machine. Therefore, in the photocopy machine in accordance with the
present invention various means and methods are provided to ensure
the safe and easy operation and maintenance. One of them is the
charging means.
The charging means used in the photocopying machine are the first
charging means 4, the simultaneous exposure-charging means 5 and
the third charging means 8. Both of the first and simultaneous
exposure-charging means are arranged as a unitary construction so
as to be easily removed from the photocopying machine proper by
lifting the unit. The third charging means 8 is also mounted so as
to be easily removed out of the machine proper.
High voltage is applied to the charging means so that the
disconnection of a charging electrode or wire will cause a serious
condition. Therefore the present invention provides an electrical
safety device for automatically disconnecting the charging means
from a power source when the charging wire or electrode should be
disconnected as will be described in more detail with reference to
FIGS. 38 and 39.
The charging means 8 includes charging wires or electrodes 400,
shield plates 401 and insulating supports 402 and 403. The
insulating supporting members 402 and 403 are fixed to the ends of
the shield plates 401 and a connector 404 is fixed to the
supporting member 403 for connection with a high voltage power
source in the main body. A knob 405 is fixed to the supporting
member 402. To the insulating supporting members 402 and 403 are
fixed by means of adjustment screws 408 and 409 control members 406
and 407 for controlling the positions of the charging electrodes
400. The control members 406 and 407 may be vertically moved by
rortating the adjustment screws 408 and 409 so that the optimum
spacing between the sensitive drum 1 and the charging electrodes
400 may be provided. The control member 407 is provided with
grooves 410 for receiving therein the charging wires 400 so as to
ensure the predetermined spacing therebetween within the shield
plates 401. One ends of the charging wires 400 are fixed to the
insulating supporting member 402 by scres 411. The other ends of
the charging wires 400 are extended through the grooves 410 of the
control member 470, wrapped around pins 412, extended through a
slot 413 of the supporting member 403 and fixed to a tension pin
415, which is normally biased to the left by a spring 414. The pin
415 is electrically connected to the connector 404.
If the charging wires 400 should be disconnected the tension pin
415 is displaced to the left and is made in contact with a
grounding plate 416 fixed by a position adjustment pin 409 and
connected with the shield plates 401, so that the high voltage is
grounded. As a consequence there is no high voltage in the charging
means 8.
As shown in FIGS. 39, insulating covers 417 and 418 are removably
fixed to the supporting members 402 and 403 in such a way that the
effective corona discharge generating portion will be kept
exposed.
SAFETY MEANS
The positive transportation of the copy paper throughout the
photocopying machine is a very important factor so that there must
be provided a safety means for safeguarding the photocopying
machine even when the copy paper is jammed in any means within the
photocopying machine. For example when the copy paper is jammed,
there must be generated a warning signal or the photocopying
machine must be immediately stopped automatically.
According to the present invention, the sensitive drum 1 starts to
rotate in response to the signal from the start button and the
control member CAM-4 is actuated. In response to the signal from
the control member CAM-4, the synchronization of the transportation
of the copy paper from the first feed rollers 58 to the image
transfer means 9 with the rotation of the sensitive drum 1 is
attained so that the developed toner image on the sensitive drum 1
may be precisely transferred onto a desired portion of the copy
paper P by the image transfer means 9. It is assumed that T.sub.1
is a time interval between the time the copy paper P is started to
be transported by the first feed rollers 58 and the time the copy
paper P actuates a sensing means 700 (See FIG. 24) disposed outside
of the fixing means. A timer (not shown) is provided with measures
a time interval T.sub.2 shorter than a time required for the
sensitive drum to make one rotation but longer than T.sub.1. The
timer is so arranged as to be actuated simultaneously when the
control member CAM-1 is actuated upon rotation of the sensitive
drum 1. If the leading edge of the copy paper P fails to reach and
actuate the sensing means 700 even after the time interval T.sub.2,
a warning signal is generated or the heating means such as lamps in
the fixing means are de-energized. Alternatively, the photocopying
machine itself may be stopped.
The sensing means 700 may be a microswitch, but it is more
preferable to use a light source 701 and a photoelectric effect
element 702 as shown in FIG. 24 so that the safe sensing may be
attained regardless of the material of copy paper or the like.
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