Electrophotographing apparatus and developing agent ejecting method

An intermittent ejection processing unit detects a driving state of at least one of driving motors of a developing agent conveying member and a stirring member which are driven at a predetermined rotational speed when a developing agent is ejected and intermittently makes each driving motor operative until a detection value of the driving state decreases to a specified value, thereby intermittently ejecting the developing agent. A continuous ejection processing unit continuously makes each driving motor operative at a predetermined rotational speed after the detection value of the driving state of at least one of the driving motors was below the specified value, thereby continuously ejecting the developing agent, and finishes the ejection of the developing agent when the detection value of the motor driving state decreases to a specified value corresponding to a no-load state by the completion of the ejection of the developing agent.

BACKGROUND OF THE INVENTION 
The present invention relates to an electrophotographing apparatus and a 
developing agent ejecting method which are used in a printer, a copying 
machine, a facsimile, or the like to which an electrophotographing 
technique is applied. More particularly, the invention relates to an 
electrophotographing apparatus and a developing agent ejecting method for 
efficiently ejecting a used developing agent from a developing device 
which is used for supplying the developing agent to develop an 
electrostatic latent image on a photosensitive drum. 
Hitherto, in such a kind of electrophotographing apparatus known as a laser 
printer, while a photosensitive drum is rotated, the surface is uniformly 
charged by a pre-charging device, a laser beam is exposed and scanned onto 
the surface of the drum, an electrostatic latent image of a pattern 
according to print information is formed, and the electrostatic latent 
image is developed by using a developing agent which is supplied by a 
developing device, thereby obtaining a toner image. On the other hand, a 
paper is fed from a hopper to a transfer position of the photosensitive 
drum and the toner image on the photosensitive drum is transferred onto 
the paper by a transfer charging device. After that, the toner on the 
paper is fixed by heat, pressure, light, or the like by a fixing device. 
As for the residual toner left on the photosensitive drum after the 
transfer, charges are eliminated by an AC discharging device and, after 
that, the residual toner is mechanically removed by a cleaning unit. 
Further, after executing an LED deelectrification for returning an 
electric potential on the photosensitive drum to an initial state (0V), 
the photosensitive drum surface is uniformly charged again by the 
pre-charging device and a subsequent printing process follows. 
In such a conventional electrophotographing apparatus, a two-component 
developing agent constructed by a toner component consisting of fine 
powder particles of a coloring resin and a fine magnetic material carrier 
component is widely used. The developing device has: a stirring device for 
stirring the two-component developing agent in a container of the 
developing agent, thereby frictionally charging the toner component and 
the magnetic material carrier component; and a magnet roller for forming a 
magnetic brush by adsorbing a part of the magnetic material carrier by a 
magnetic force. The toner component is supplied from an exchangeable toner 
vessel. The magnet roller is exposed at a position of a developing region 
which faces the photosensitive drum. The toner component is 
electrostatically adhered to the head of the magnetic brush adsorbed and 
formed around the magnet roller and is conveyed to the developing region 
on the photosensitive drum, so that an electrostatic latent image is 
developed. A development concentration of the electrostatic latent image 
on the photosensitive drum in this case depends on an amount of toner 
which is conveyed to the developing region. In order to uniform the 
development concentration, a length of head of the developing agent which 
is formed as a magnetic brush onto the magnet roller is restricted by a 
doctor blade. The developing agent in which the toner component is reduced 
by the development is scraped from the magnet roller by a scraper and is 
returned to the stirring device side. The toner corresponding to a 
consumed amount is supplemented by the stirring device and the 
concentration is returned to a specified toner concentration. The toner is 
again used for development. When the toner component is consumed during 
the use and the specified toner concentration cannot be assured, a toner 
vessel is exchanged. 
In the conventional electrophotographing apparatus, when a predetermined 
number of papers are printed, the developing agent in the developing 
device is replaced. This is because the magnetism of the magnetic carrier 
of the developing agent drops by an aging change and a printing ability 
deteriorates. This is called a developing agent life. In order to replace 
the developing agent, it is necessary to eject the used developing agent 
from the developing device. Generally, an ejecting port in the bottom 
plate of the developing device is opened, the magnet roller and a stirring 
screw are operated, and the developing agent in the developing device is 
completely ejected. In the case where the electrophotographing apparatus 
of this kind is used in a printing apparatus of a computer system, when 
the developing agent reaches the developing agent life during the 
operation of the system and a replacement of the developing agent is 
requested, since the developing agent is replaced in a state where the 
printing process is interrupted, it is requested to completely eject the 
developing agent in a short time. If the developing agent is not 
completely ejected in this instance, the developing agent in the 
developing device becomes too much after the replacement. A drive load of 
the developing device increases, so that the developing device cannot be 
driven or the developing agent overflows from the vessel. Further, when 
the toner concentration is controlled by using a magnetic permeability 
sensor, there is a problem such that the toner concentration is largely 
deviated from the specified value and is shifted to the high side, or the 
like. Consequently, in order to eject the developing agent completely, an 
ejecting work is certainly executed by taking a certain extent of time. In 
case of ejecting the developing agent by driving the magnet roller and 
stirring screw, for a predetermined period of time after the start of the 
ejection of the developing agent from the casing of the developing device, 
a large amount of developing agent is conveyed to a developing agent 
ejecting port by the stirring screw. When an amount of developing agent in 
the developing device decreases to a predetermined amount or less, the 
amount of developing agent is gradually reduced. In order to smoothly lead 
a large amount of developing agent for the predetermined period of time 
from the start of the ejection to a collecting vessel on the outside of 
the apparatus, a cross-sectional area of a minimum channel of a funnel 
provided at the ejecting port and a cross-sectional area of a channel of a 
hose have to be set to predetermined values or more, so that there is a 
certain limit when the apparatus is miniaturized. In recent years, not 
only the miniaturization of the apparatus but also the realization of an 
advanced function and a multi-function are strongly requested. With 
respect to a structure which is not usually used and is used for ejecting 
the developing agent, a miniaturization is also strongly requested, so 
that it is tried to use a small funnel and a small hose. If the small 
funnel is used, however, when a large amount of developing agent is 
dropped, the developing agent causes a bridge phenomenon and clogs in the 
funnel. When the hose is narrowed, the developing agent clogs in the hose. 
Consequently, a problem such that the developing agent overflows around 
the funnel into the apparatus occurs. In a printer, a copying machine, a 
facsimile, or the like, it is strongly requested to eject the developing 
agent at a high speed. In order to realize the high ejecting speed, 
rotational speeds of the magnet roller and the stirring screw are raised. 
However, since a large amount of developing agent is dropped to the funnel 
in association with an increase in speed, the developing agent clogs in 
the funnel and the hose and a problem of the overflow of the developing 
agent around the funnel into the apparatus occurs. 
SUMMARY OF THE INVENTION 
According to the invention, there is provided an electrophotographing 
apparatus in which the ejection driving of a developing agent conveying 
member and a stirring device of a developing device can be properly 
executed in accordance with an ejection state of a developing agent and 
the developing agent can be completely ejected in a short time. 
It is an object of the invention to provide an electrophotographing 
apparatus comprising: a stirring member such as a stirring screw or the 
like for stirring a developing agent enclosed in a vessel; a developing 
agent conveying member such as a magnet roller or the like for adsorbing 
the developing agent and developing an electrostatic latent image on a 
photosensitive material, for example, a photosensitive drum; and a 
developing device having an ejecting port for ejecting the developing 
agent. According to the invention, an intermittent ejection processing 
unit and a continuous ejection processing unit are provided for such an 
electrophotographing apparatus. The intermittent ejection processing unit 
detects a driving state of at least one of driving motors of the 
developing agent conveying member and the stirring member which are driven 
at a predetermined rotational speed when the developing agent is ejected 
and intermittently operates each of the driving motors until a detection 
value of the driving state drops to a specified value, thereby 
intermittently ejecting the developing agent. After the detection value of 
the driving state of at least one of the driving motors is below the 
specified value, the continuous ejection processing unit continuously 
drives each of the driving motors at a predetermined rotational speed, 
thereby continuously ejecting the developing agent. Further, when the 
detection value of the motor driving state decreases to the specified 
value corresponding to a no-load state by completion of the ejection of 
the developing agent, the continuous ejection processing unit finishes the 
ejection of the developing agent. The intermittent ejection processing 
unit and the continuous ejection processing unit detect a motor drive 
current or a motor drive torque as a driving state of at least one of the 
driving motors. Since the ejecting state of the developing agent is 
recognized from the driving state such as current or torque of the motor 
which is driven at the time of ejection and the operating mode is switched 
from the intermittent operation to the continuous operation, the optimum 
switching operation can be performed in accordance with fluctuation 
factors such as amount of developing agent to be actually ejected, toner 
concentration, lot difference, deterioration state according to printing 
conditions, apparatus environment such as a temperature or the like, and 
the like. Since the end of the ejection is also determined by the drive 
current or the drive torque corresponding to the no-load state, a 
situation such that the developing agent is not completely ejected or the 
operation is executed for a longer time than it is needed after completion 
of the ejection is prevented and the developing agent can be completely 
ejected in a short time. 
Another embodiment of the invention is characterized in that an 
intermittent ejection processing unit is used as a continuous ejection 
processing unit and after a detection value of a driving state of at least 
one of driving motors was below a specified value, the intermittent 
ejection processing unit continuously ejects a developing agent by a 
continuous operation in which a drive current of each driving motor is 
fixed to a predetermined value, and a rotational speed is detected, and 
when the rotational speed increases to a specified rotational speed 
corresponding to a no-load state by the completion of the ejection of the 
developing agent, the intermittent ejection processing unit finishes the 
ejection of the developing agent. In this case, the intermittent ejection 
processing unit detects a motor drive current or a motor drive torque as a 
driving state of at least one of the driving motors. 
According to the invention, a developing agent ejecting method of an 
electrophotographing apparatus is also provided. The developing agent 
ejecting method comprises: an intermittent ejecting step of detecting a 
driving state of at least one of driving motors of a developing agent 
conveying member and a stirring member which are driven at a predetermined 
rotational speed when a developing agent is ejected and, intermittently 
operating each of the driving motors until a detection value of the 
driving state decreases to a specified value, thereby intermittently 
ejecting the developing agent; a continuous ejecting step of continuously 
operating each of the driving motors at a predetermined rotational speed 
after the detection value of the driving state of each of the driving 
motors in the intermittent operation was below the specified value, 
thereby continuously ejecting the developing agent; and an ejection 
finishing step of finishing the ejection of the developing agent when the 
detection value of the motor driving state decreases to the specified 
value corresponding to a no-load state by the completion of the ejection 
of the developing agent in the continuous ejecting step. 
According to another embodiment of the invention, there is provided a 
developing agent ejecting method comprising: an intermittent ejecting step 
of detecting a driving state of at least one of driving motors of a 
developing agent conveying member and a stirring member which are driven 
at a predetermined rotational speed when a developing agent is ejected and 
intermittently operating each of the driving motors until a detection 
value of the driving state decreases to a specified value, thereby 
intermittently ejecting the developing agent; a continuous ejecting step 
of continuously ejecting the developing agent by a continuous operation in 
which a drive current of each of the driving motors is fixed to a 
predetermined value after the detection value of the driving state of any 
one of the driving motors was below the specified value; and an ejection 
finishing step of finishing the ejection of the developing agent when a 
rotational speed of at least one of the driving motors increases to a 
specified rotational speed corresponding to a no-load state by the 
completion of the ejection of the developing agent in the continuous 
ejecting step. 
The above and other objects, features, and advantages of the present 
invention will become more apparent from the following detailed 
description with reference to the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows an embodiment of an electrophotographing apparatus to which 
the invention is applied, in which a page printer 10 is shown as an 
example. In the page printer 10, continuous papers 14 are enclosed in a 
hopper 12. The continuous paper 14 pulled from the hopper 12 is led to an 
electrophotograph printing mechanism of an image forming unit 16 having a 
developing device 22 and a photosensitive drum 24 and a toner image is 
transferred. The transferred image is fixed onto the continuous paper 14 
by a fixing device 18. The continuous paper 14 is folded and stacked in a 
stacker 20. In the image forming unit 16, the surface of the 
photosensitive drum 24 is uniformly charged by charging devices 26-1 and 
26-2 arranged around the photosensitive drum 24 which rotates at a 
predetermined speed and is exposed by a light emission driving according 
to print information of LED print heads 28-1 and 28-2, thereby forming an 
electrostatic latent image onto the surface of the photosensitive drum 24. 
A toner image is developed by the developing device 22 for the 
electrostatic latent image formed on the photosensitive drum 24 and the 
toner image is transferred onto the continuous paper 14 by a transfer 
charging device 29. After transferring the toner image, the surface of the 
photosensitive drum 24 is discharged by a discharging and charging device 
30. After that, residual toner is removed from the surface of the 
photosensitive drum 24 by a cleaning brush 32 and a cleaning blade 34, 
After the surface of the photosensitive drum 24 was finally uniformly 
discharged by an irradiation of a light by a deelectrifying LED 36, the 
processes from the initial charging by the charging devices 26-1 and 26-2 
are repeated. The developing device 22 for developing the electrostatic 
latent image formed on the surface of the photosensitive drum 24 has a 
toner hopper 25. 
FIG. 2 shows a detailed construction of the developing device 22 in FIG. 1. 
A two-component developing agent comprising a toner component consisting 
of fine powder particles of a color resin and a fine magnetic material 
carrier component is enclosed in a developing device casing 42 of the 
developing device 22. The toner component in the two-component developing 
agent has a mean diameter of, for example, 10 .mu.m and the magnetic 
material carrier has a mean diameter of 80 .mu.m. The toner for the 
developing device casing 42 is supplied from the toner hopper 25. The 
toner hopper 25 has therein a toner supply roller 40. When a detection 
value of a toner concentration sensor (magnetic permeability sensor) 54 
provided in the developing device casing 42 is equal to or less than a 
specified value, by driving the toner supply roller 40 at a specified 
rotational speed for a specified time, a predetermined amount (for 
example, 0.5 g) of toner is supplemented at a time. The toner supplied 
from the toner hopper 25 to the developing device casing 42 is sent to a 
first stirring screw 46-1 by two conveying paddles 44-1 and 44-2 and is 
sent in the axial direction while being stirred with the developing agent 
in the casing by the first stirring screw 46-1. The toner is sent back 
from a feeding end of an axial edge portion to a second stirring screw 
46-2. The second stirring screw 46-2 is rotated clockwise which is 
opposite to the counterclockwise rotating direction of the first stirring 
screw 46-1. Consequently, the developing agent fed from the first stirring 
screw 46-1 side is sent in the axial direction as a reverse direction by 
the second stirring screw 46-2. The two-component developing agent is 
circulated in the developing device casing 42 by the first stirring screw 
46-1 and second stirring screw 46-2 and the toner component and the 
magnetic material carrier component are mutually frictionally charged by 
stirring. In the two-component developing agent circulated by the first 
stirring screw 46-1 and second stirring screw 46-2, the magnetic material 
carrier is adhered around a conveyer roller 48 using a magnet roller, 
thereby forming a magnetic brush. The toner component is electrostatically 
adhered to the head of the magnetic brush and is supplied to three 
developing magnet rollers arranged around the upper photosensitive drum 
24. In a manner similar to the conveyor roller 48, developing magnet 
rollers 50-1 to 50-3 adsorb the magnetic material carriers around the 
rollers and form magnetic brushes. The toner component from the conveyor 
roller 48 is electrostatically adsorbed to the head of each of the 
magnetic brushes. The developing magnet rollers 50-1 to 50-3 rotate 
counterclockwise. On the other hand, the photosensitive drum 24 rotates 
clockwise. For example, the photosensitive drum 24 has a diameter of 80 mm 
and rotates clockwise at a peripheral velocity of 200 mm/sec. Each of the 
developing magnet rollers 50-1 to 50-3 of the developing device 22 has, 
for example, a diameter of 50 mm and rotates counterclockwise at a 
peripheral velocity of 400 mm/sec. The developing magnet rollers 50-1 to 
50-3 provided for the developing device 22 are disposed, for example, with 
intervals of 2 mm for the developing region of the photosensitive drum 24. 
The developing magnet rollers 50-1 to 50-3 adsorb the magnetic material 
carriers and form magnetic brushes. The toner component conveyed by the 
conveyor roller 48 is electrostatically adhered to the head of each 
magnetic brush. The toner component is conveyed to the developing region 
of the photosensitive drum and the electrostatic latent image is 
developed, thereby forming a toner image. A length of head of the 
developing agent of the magnetic brush formed on each of the developing 
magnet rollers 50-1 to 50-3 is restricted by a doctor blade (not shown), 
thereby uniforming a development concentration. When a predetermined 
specified number of papers were printed and a life of the developing agent 
enclosed in the developing device 22 reaches a developing agent life, a 
lid 78 provided on the bottom of the developing device casing 42 is opened 
by being rotated downward around an axis 80 as a center. A collecting 
bottle 84 is connected to a funnel 76 by a hose 82 and the developing 
agent in the developing device 22 is ejected. As for an opening operation 
of the lid 78 provided at a developing agent ejecting port 45, as shown in 
FIG. 3, the end of the axis 80 is projected to the outside of the 
developing device casing 42 and a developing agent ejection lever 85 is 
provided at the end. By rotating the developing agent ejection lever 85, 
the lid 78 is opened and the developing agent can be ejected. When the 
developing agent is ejected from the developing device 22, in the 
invention, an ejection control of two stages of an intermittent rotation 
and a continuous rotation of the conveying paddles 44-1 and 44-2, first 
and second stirring screws 46-1 and 46-2, conveyor roller 48, and further, 
developing magnet rollers 50-1 to 50-3 is executed. 
FIG. 4 shows a driving mechanism of the conveying paddles 44-1 and 44-2, 
first and second stirring screws 46-1 and 46-2, conveyor roller 48, and a 
collecting magnet roller 52 which are provided in the developing device 22 
in FIG. 2. In the driving mechanism, a rotation of a stirring motor 56 is 
transferred to a reduction gear 58 by a belt transfer mechanism 60, an 
output rotation reduced by the reduction gear 58 is transferred to a belt 
transfer mechanism 64 by a transfer mechanism 62, and the conveying 
paddles 44-1 and 44-2, first and second stirring screws 46-1 and 46-2, 
conveyor roller 48, and further, collecting magnet roller 52 are 
interlockingly rotated. Further, in the invention, a rotation detector 66 
for detecting a motor rotational speed is provided for the stirring motor 
56. 
FIG. 5 shows a driving mechanism of the developing magnet rollers 50-1 to 
50-3 provided in the developing device 22 in FIG. 2. In the driving 
mechanism, a rotation of a developing motor 68 is transferred to a 
reduction gear 72 by a belt transfer mechanism 70 and is reduced and an 
output rotation reduced by the reduction gear 72 is transferred to a belt 
transfer mechanism 75 by a transfer mechanism 74, thereby interlockingly 
rotating the three developing magnet rollers 50-1 to 50-3. 
FIG. 6 is a functional block diagram for a developing agent ejection 
control in the electrophotographing apparatus of the invention and such a 
control is realized as a control function of a controller 100 provided in 
the page printer 10 of FIG. 1. Further, a schematic plan view of the 
portions of the first and second stirring screws 46-1 and 46-2 and 
developing magnet roller 50-1 which are provided in the developing device 
22 in FIG. 2 is together shown. The stirring motor 56 and developing motor 
68 for driving them are also shown. With respect to the first and second 
stirring screws 46-1 and 46-2 provided in the developing device 22, for 
example, the first stirring screw 46-1 is rotated counterclockwise when it 
is seen from the stirring motor 56 and the second stirring screw 46-2 is 
rotated clockwise as a reverse direction, so that the developing agent 
enclosed in the developing device 22 is circulated therein as shown by 
arrows A and B. A processor 102 is provided for the controller 100 and a 
developing agent ejection control unit 104 is also provided as a control 
function of the processor 102. The processor 102 has hardware such as CPU, 
ROM, and the like. The developing agent ejection control unit 104 of the 
processor 102 has functions of an intermittent ejection processing unit 
106 and a continuous ejection processing unit 108 in order to execute the 
developing agent ejection control of the invention. Drivers 110 and 112, 
A/D converters 116 and 118, and further, a current detecting circuit 114 
are provided for input/output units of the processor 102. The driver 110 
drives the developing motor 68 in the developing device 22. The driver 112 
drives the stirring motor 56 in the developing device 22. The current 
detecting circuit 114 detects a drive current of the stirring motor 56 in 
the developing device 22. The drive current of the stirring motor 56 
detected by the current detecting circuit 114 is converted to digital data 
by the A/D converter 116 and is inputted to the processor 102. In order to 
realize another embodiment of the invention, the rotation detector 66 is 
further provided for the stirring motor 56. The rotational speed of the 
stirring motor 56 detected by the rotation detector 66 is converted to 
digital data by the A/D converter 118 and is inputted to the processor 
102. The intermittent ejection processing unit 106 provided for the 
developing agent ejection control unit 104 detects the drive current of 
the stirring motor 56 which is driven at a predetermined rotational speed 
when the developing agent is ejected and continuously operates the 
stirring motor 56 and developing motor 68 at a predetermined on/off period 
until the drive current decreases to a predetermined specified value, 
thereby intermittently ejecting the developing agent. The continuous 
ejection processing unit 108 continuously operates the stirring motor 56 
and developing motor 68 at a predetermined rotational speed, thereby 
continuously ejecting the developing agent. The developing agent ejecting 
operation is finished when the motor drive current decreases to a 
predetermined specified value corresponding to a no-load state indicative 
of the completion of the ejection of the developing agent. Further, a 
power source unit 120 is provided for the controller 100, thereby 
supplying a power source to the respective units. 
An ejecting process by the developing agent ejection control unit 104 in 
FIG. 6 will now be described with reference to a flowchart of FIG. 7. When 
the developing agent reaches the developing agent life during the 
operation of the electrophotographing apparatus, for example, the page 
printer of FIG. 1, a code number or a message indicative of a request to 
exchange the developing agent is outputted to an operation display panel 
or the like. Upon receipt of the developing agent exchange request, as 
shown in FIGS. 2 and 3, the operator connects the collecting bottle 84 to 
the funnel 76 provided in the bottom portion of the developing device 
casing 42 by the hose 82 and, subsequently, operates the developing agent 
ejection lever 85 provided in the front portion of the developing device 
casing 42 and opens the lid 78 of the developing agent ejection port 45 in 
step S1, thereby preparing for ejection of the developing agent. When the 
preparation for ejection of the developing agent is finished, the operator 
activates the developing agent ejection control by operating the operation 
panel or the like. When the developing agent ejection control is started, 
in step S2, the developing agent ejection control unit 104 drives the 
stirring motor 56 and developing motor 68 by the drivers 110 and 112, 
thereby making the developing magnet rollers 50-1 to 50-3, first and 
second stirring screws 46-1 and 46-2, magnet roller 48, and conveying 
paddles 44-1 and 44-2 operative at a predetermined rotational speed R=R0 
for a predetermined time T1, for example, T1=2 seconds. During the 
operation for time T1, a drive current I1 of the stirring motor 56 is 
measured in step S3 and is compared with a predetermined specified value 
Ith in step S4. When the measured drive current I1 is equal to or larger 
than the specified value Ith, the processing routine advances to step S5 
and the operations of the stirring motor 56 and developing motor 68 are 
stopped for a predetermined time T2, for example, T2=1 second. The 
processing routine is returned to step S2 and the motor rotation for the 
predetermined time T1 is repeated. For a period of time during which the 
drive current I1 of the stirring motor 56 is equal to or larger than the 
specified value Ith, therefore, the stirring motor 56 and developing motor 
68 repeat an intermittent rotation such that they operate for T1=2 seconds 
and stop for T2=1 second. Consequently, the developing agent is ejected by 
the intermittent rotation of the first and second stirring screws 46-1 and 
46-2 and developing magnet rollers 50-1 to 50-3. At the initial stage of 
the ejection of the developing agent, since the ejection amount of the 
developing agent from the ejecting port 45 is large, a clogging is likely 
to occur. However, the clogging of the developing agent at the ejecting 
port 45 is prevented by the intermittent rotation, so that even in a state 
of a large amount of developing agent, the developing agent can be 
efficiently ejected. 
FIG. 8 is a characteristics diagram of a motor current consumption of the 
stirring motor 56 for the amount of developing agent in the developing 
device 22 in FIG. 7. The characteristics diagram shows a case where the 
stirring motor 56 is driven at the predetermined rotational speed R=R0. 
The developing agent amount before ejection of the developing agent is set 
to be full and a motor drive current in this instance is set to Imax. When 
the amount of developing agent decreases by the ejection of the developing 
agent, a motor load by the first and second stirring screws 46-1 and 46-2 
is reduced and the motor drive current necessary to maintain the 
predetermined rotational speed R0 also consequently decreases. The 
characteristics diagram is expressed by a linear approximation in FIG. 8 
in order to simply describe an environment in which the motor drive 
current decreases for the amount of developing agent. The amount of 
developing agent in the developing device 22 can be, therefore, estimated 
from the motor drive current. As a specified value Ith in step S4 in FIG. 
7, for example, the motor drive current Ith when the amount of developing 
agent is reduced to the half in FIG. 8 is used. For a period of time 
during which the amount of developing agent is reduced from the full state 
to the half, the ejection control of the developing agent by the 
intermittent rotation of the developing magnet rollers 50-1 to 50-3 and 
first and second stirring screws 46-1 and 46-2 in steps S2 to S5 in FIG. 7 
is executed. The control of the intermittent ejection in steps S2 to S5 
corresponds to the control function that is executed by the intermittent 
ejection processing unit 106 provided in the developing agent ejection 
unit 104 in FIG. 6. 
When the drive current I1 of the stirring motor 56 is below the specified 
value Ith in association with the ejection of the developing agent, the 
processing routine advances to step S6. The stirring motor 56 and 
developing motor 68 are continuously driven so as to continuously make the 
developing magnet rollers 50-1 to 50-3 and first and second stirring 
screws 46-1 and 46-2 operative at a predetermined value of the rotational 
speed of R=R0. Subsequently, the drive current I1 of the stirring motor 56 
is measured in step S7 and is compared with a specified value Imin in step 
S8. As will be obviously understood from the characteristics diagram of 
FIG. 8, the specified value Imin is a motor drive current when the 
developing agent is completely ejected and the amount becomes zero, 
namely, what is called a no-load current of the stirring motor 56 when 
there is no developing agent. The continuous ejecting operation for 
continuously driving the developing magnet rollers 50-1 to 50-3 and first 
and second stirring screws 46-1 and 46-2 at the predetermined rotational 
speed R0 in steps S6 and S7 is repeated until the current consumption I1 
of the stirring motor 56 is equal to or less than the specified value Imin 
in step S8. When the drive current I1 is equal to or less than the 
specified value Imin in step S8, step S9 follows and a count value of a 
counter N is increased by one. In step S10, a check is made to see whether 
the counter N has reached, for example, N=3. If N=3, it is determined that 
the developing agent has completely been ejected and a process for 
finishing the ejection of the developing agent is executed in step S11. 
That is, the code number or message indicative of the end of the 
developing agent ejection is outputted and displayed on the operation 
display panel. The hose 82 connected as shown in FIG. 2 is disconnected, 
the developing agent ejecting port 45 is closed, and the developing agent 
is newly supplied from a developing agent input port 86 provided in the 
upper portion of the developing device casing 42 shown in FIG. 3 into the 
developing device casing 42. In the processes in steps S9 and S10, it is 
determined for the first time that the ejection of the developing agent 
has completely been finished when the drive current I1 of the stirring 
motor 56 reaches the specified value Imin in the no-load state indicative 
of the ejection of the developing agent three times in a row. 
Consequently, a phenomenon such that in a state where there is a little 
amount of developing agent, the motor drive current I1 instantaneously 
decreases to Imin or less indicative of the no-load state, and the 
ejection end is determined. 
FIG. 9 is a flowchart for another control process of the developing agent 
ejection control in the electrophotographing apparatus of the invention. 
The ejection control process is characterized in that the completion of 
the ejection of the developing agent after the driving mode was switched 
from the intermittent ejection drive to the continuous ejection drive is 
discriminated from the rotational speed of the stirring motor. Processes 
in steps S1 to S5 are the same as those in the ejection controlling 
process of FIG. 7. As shown in the characteristics diagram of FIG. 8, for 
example, the intermittent ejection control in which the operation of the 
developing magnet rollers 50-1 to 50-3 and first and second stirring 
screws 46-1 and 46-2 at the predetermined rotational speed of R0 for T1=2 
seconds and the stop for T2=1 second are repeated until the amount of 
developing agent decreases to the one-half, that is, the motor drive 
decreases to Ith. When the drive current I1 of the stirring motor 56 is 
below the specified value Ith in step S3 during the intermittent ejection, 
the processing routine advances to step S6. The stirring motor 56 and 
developing motor 68 are driven by the specified drive current Ith and the 
developing magnet rollers 50-1 to 50-3 and first and second stirring 
screws 46-1 and 46-2 are continuously operated. Subsequently, in step S7, 
the rotational speed of the stirring motor 56 is measured on the basis of 
a detection signal from the rotation detector 66. In step S8, a check is 
made to see if the rotational speed R is equal to or larger than a 
predetermined specified rotational speed Rmax. The specified rotational 
speed Rmax is determined in accordance with the characteristics of the 
motor rotational speed of the stirring motor 56 for the amount of 
developing agent in FIG. 10. 
The characteristics diagram of FIG. 10 shows a change in the motor 
rotational speed R for the reduction in the amount of developing agent 
when the drive current I1 of the stirring motor 56 is fixed to I1=Ith. 
When the amount of developing agent decreases in a state where the motor 
drive current is set to the fixed value Ith, the motor rotational speed R 
increases by the reduction of the drive load. In this case, the relation 
of the motor rotational speed to the reduction in amount of the developing 
agent is treated on the assumption that it linearly increases for 
simplicity of explanation. Since the motor enters the no-load state when 
the amount of developing agent becomes zero, the motor rotational speed at 
this time becomes the maximum value Rmax. Therefore, in case of executing 
the continuous operation while setting the drive current of the stirring 
motor 56 to the fixed value Ith, whether the motor rotational speed 
reaches the maximum rotational speed Rmax in the no-load state 
corresponding to zero amount of the developing agent or not is 
discriminated, thereby enabling the completion of the ejection of the 
developing agent to be determined. 
When the rotational speed R of the stirring motor 56 is equal to or less 
than the specified value Rmax in association with the reduction in amount 
of the developing agent in step S8, the processing routine advances to 
step S9 and the count value of the counter N is increased by one. The 
processes in steps S6 to S9 are repeated until the count value of the 
counter N is equal to, for example, N3 in step S10. After it was confirmed 
that the developing agent had completely been ejected, as a process for 
finishing the ejection of the developing agent, a code number or a message 
indicative of the end of the ejection is displayed in step S11. 
Although the drive current of the stirring motor 56 is detected as shown in 
FIG. 6 and the developing agent ejection control of FIG. 7 is executed in 
the embodiment, the drive current of the developing motor 68 is detected 
and an ejection control can be also similarly executed. With respect to 
the embodiment for discriminating the completion of the ejection of the 
developing agent from the motor rotational speed in FIG. 9 as well, the 
above detection can be also realized by providing the rotation detector 66 
for the developing motor 68. 
Although the drive current of the stirring motor 56 is detected and the 
intermittent ejection control and the continuous ejection control are 
executed step by step in the embodiment of FIG. 6, by detecting the drive 
torque of the stirring motor 56 instead of the motor drive current, the 
ejection control can be similarly executed. This point can be also 
similarly applied to a case of detecting the drive torque of the 
developing motor 68. 
Although the value when the amount of developing agent is reduced to 1/2 is 
used as a specified value Ith of the motor drive current for switching 
from the intermittent ejection control to the continuous ejection control 
in the characteristics diagram of FIG. 8, the invention is not limited to 
such an example. The motor drive current Ith corresponding to an optimum 
amount of the developing agent for switching from the intermittent 
ejection of the developing agent to the continuous ejection can be 
properly determined by experiments or the like. The specified value Imin 
corresponding to the no-load state which is used for discrimination about 
the end of the ejection of the developing agent in FIG. 8 and the maximum 
rotational speed Rmax in FIG. 10 can be also similarly experimentally 
determined. 
Although the shift from the intermittent operation of the ejection control 
to the continuous operation is determined by the motor drive current in 
the foregoing embodiment, the intermittent operation can be also fixedly 
switched to the continuous operation by a time determined by experiments. 
According to the invention as mentioned above, since the ejection situation 
of the developing agent is recognized from the actual driving state such 
as a current or torque of the motor which is driven when the developing 
agent is ejected and the operating state is switched from the intermittent 
operation to the continuous operation, the optimum switching timing 
adapted to the fluctuation factors such as amount of the developing agent 
which is actually ejected, toner concentration, lot difference, 
deterioration state according to the print conditions, apparatus 
environment such as a temperature or the like, and the like can be set. 
Since the end of the ejection of the developing agent is also 
discriminated by the drive current, drive torque, and further, rotational 
speed corresponding to the no-load state of the motor which is driven at 
the time of the ejection, a situation such that the developing agent is 
not completely ejected or contrarily, the operation is executed for a 
longer time than it is needed after completion of the ejection can be 
prevented. Thus, the complete ejection of the developing agent can be 
realized in a short time. According to the switching from the intermittent 
operation to the continuous operation by the predetermined time that was 
experimentally decided, it is not necessary to detect the motor current, 
torque, rotational speed, and the like and the ejection control of the 
developing agent can be easily certainly realized.