BACKGROUND OF THE INVENTION
[0001] The present invention relates to a toner replenishing device of an electrophotographic
copying machine.
[0002] In a toner replenishing device of a popular type for a copying machine wherein two-component
developers are used, a toner replenishing room located over a developer agitating
chamber in the toner replenishing device is provided, at its opening, with a toner
replenishing roller whose rotation causes toners to fall into the toner agitating
chamber.
[0003] Following replenishing methods have so far been known as a conventional toner replenishing
method.
(1) A toner replenishing method wherein a toner replenishing roller is provided with
gauge grooves arranged on the surface of the roller in parallel with the roller axis,
and excessive toners sticking to the roller surface are scraped off by a gauging blade
arranged to be in a sliding contact to the roller surface, thus toner in a constant
amount is replenished for each replenishment (Japanese Patent Publication Open to
Public Inspection No. 6872/1982 (hereinafter referred to as Japanese Patent O.P.I.
Publication)).
(2) A toner replenishing method wherein a replenishing roller is provided thereon
with spiral grooves and a scraper that is in a sliding contact with the roller surface
scrapes off excessive toners, thus toner is replenished (Japanese Patent O.P.I Publication
No. 56948/1975).
(3) A toner replenishing method wherein toner is fed out of a toner replenishing room
by elastic fine bristles (metallic or nylon brush or the like) flocked on the surface
of a toner replenishing roller and then are scraped off by a scraper (Japanese Patent
O.P.I. Publication No. 60933/1979).
[0004] However, aforesaid conventional replenishing devices have had a problem that toner
replenished into a developer agitating chamber can not be mixed uniformly with carrier
in the developer agitating chamber.
[0005] Namely, in the aforesaid methods (1), (2), and (3), scraped toners fall in a form
of a clod and the clod stays in the agitating chamber, thus toners sometimes can not
be mixed uniformly with carrier.
[0006] An effective method to avoid such phenomenon is represented by the method (Japanese
Patent O.P.I. Publication No. 7073/1987) wherein an opening of a toner replenishing
room is so arranged as to contact with the developer in a developer agitating chamber
and toner is conveyed by a carrier brush formed round a toner replenishing roller
provided at the opening. In a small-sized copying machine, however, this method can
not be employed because of the restriction in terms of design; in many cases, the
toner replenishing room has to be provided over the developer agitating chamber.
SUMMARY OF THE INVENTION
[0007] In view of the aforesaid points, an object of the present invention is to offer a
toner replenishing device wherein it is possible to replenish toners from a toner
replenishing room provided over a developer agitating chamber, while mixing the toner
with carrier in advance.
[0008] In order to attain the aforesaid object, a toner replenishing device of the invention
is represented by the device wherein a toner replenishing roller whose circumference
is provided with S-poles and N-poles magnetized thereon one after the other is provided
at the lower opening of the toner replenishing room that replenishes toners into a
two-component developer agitating chamber, a toner-spill-prevention member is provided
on the toner outlet side at the aforesaid opening and a carrier brush height regulating
member is provided on the side opposite to the aforesaid toner outlet side, thereby
toners can be replenished while toner is conveyed by the carrier brush and toner and
carrier are mixed in advance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Fig. 1 shows an overall structural view of a copying machine wherein a toner replenishing
device of the invention is incorporated, Fig. 2 is a sectional view of the device
of the invention, Fig. 3 is an illustration of principle showing an example wherein
a toner-spill-prevention member is made of a gutter-formed member, Fig. 4 is an illustration
of principle showing an example wherein a toner-spill-prevention member is made of
a flexible film and each of Figs. 5 (a), (b) and (c) is an illustration showing how
toner is conveyed by carrier brushes. Fig. 6 is an illustration showing how a carrier
pool is generated and showing the relation between t₁ and t₂. Fig. 7 (a) is a perspective
view of a roller-stopping means, Fig. 7 (b) is a sectional view showing engagement
among gear train and Fig. 8 is an illustration showing the brush hanging down.
DETAILED DESCRIPTION OF THE INVENTION
[0010] The invention will be explained as follows, referring to an example shown in attached
drawings.
[0011] Fig. 1 shows an overall structural view of a copying machine wherein a toner replenishing
device of the invention is incorporated, Fig. 2 is a sectional view of the toner replenishing
device of the invention, Fig. 3 is an illustration of principle showing an example
wherein a toner-spill-prevention member is made of a gutter-formed member, Fig. 4
is an illustration of principle showing an example wherein a toner-spill-prevention
member is made of a flexible film and each of Figs. 5 (a), (b) and (c) is an illustration
showing how toner is conveyed by carrier brushes.
[0012] In the figure, the numeral 1 is a main body of a toner replenishing device of the
inventions and the main body 1 is incorporated in copying machine 100 together with
main supplying chamber 11 provided adjacently. The copying machine 100 is provided
thereon with exposure unit 20 and is provided therein with developing unit 10, paper-feeding
unit 30, fixing unit 40, paper-ejecting section 50 and transfer/separation unit 60.
[0013] The exposure unit 20 is provided thereon with platen glass 21 on which a document
to be copied is placed, document-holding plate 22 that covers the glass 21, and further
with light source-moving optical system 23 that illuminates a document surface on
the glass 21 while traveling under the glass 21. The numeral 24 is a light source
lamp provided on moving carriage 25, and 26a, 26b, 26c and 26d are reflecting mirrors.
The light emitted from the light source lamp 24 is reflected on the surface of a document
placed on platen glass 21 and then is projected on photoreceptor drum 14 that will
be stated later, through reflecting mirrors 26a, 26b, 26c and 26d. The aforesaid paper-feeding
unit 30 is for feeding image-transfer papers loaded on paper-tray 31.
[0014] Developing unit 10 is arranged at the lower part of the aforesaid main body 1 and
is composed of developer agitating chamber 12 and developer roller 13 that is adjacent
to the agitating chamber 12. Inside the aforesaid main supplying chamber 11, there
are provided toner cartridge 15, that is detachable, and toner conveying member 16,
thus toner T ejected from the aforesaid toner cartridge 15 can be stored in the bottom
portion 11a of the main supplying chamber 11. Toner T can be supplied at any time
to the adjacent replenishing room 2 of main body 1 through the aforesaid toner conveying
member 16 that rotates to move toners T upward obliquely.
[0015] The aforesaid main body 1 is provided with toner replenishing room 2 and toner replenishing
roller 3 as primary structural factors, and the toner replenishing room 2 is provided
at its upper portion with toner-inlet 2a for the toner T fed from the aforesaid main
supplying chamber 11 and is provided at its lower side with the opening 4 for toner
replenishing. The toner replenishing room 2 is further provided with the aforesaid
toner replenishing roller 3 at the aforesaid opening 4 located at the lower side of
the replenishing room, thus the toner replenishing room can receive, being linked
with the upper end portion of the aforesaid toner conveying member 16, the toner T
through toner inlet 2a. On the side wall 4a at the toner outlet side on the aforesaid
opening 4, there is provided toner-spill-prevention member 5; and on the wall side
opposite to the aforesaid wall side 4a, there is provided carrier brush height regulating
member 6. The aforesaid toner replenishing roller 3 is provided with S-poles and N-poles
magnetized one after the other along its outer circumference 3a, and the magnetic
poles enable magnetic carriers C (iron powder or the like) to be attracted magnetically
thereto and thereby to form a brush H of carrier C on the aforesaid outer circumference
3a. The number of poles to be magnetized on the aforesaid roller 3 may be any of 2,
4, 6 and 8, and in the example wherein the number of poles is 4, there is formed locally
the brush H (Fig. 5 (a)) at the magnetizing portion, and when the roller 3 rotates,
the brush H sweeps the inside of the toner replenishing room 2 and takes toner T in
the brush H to convey them to the lower opening 4 (Figs. 5 (b) and (c))
[0016] Aforesaid toner-spill-prevention member 5 is for preventing, by means of carrier
brush H, the toners T from dropping through the clearance between the side wall 4a
at toner outlet side on the opening 4 and toner replenishing roller 3, and it is made
of a gutter-formed member having a J-formed sectional view and protrudes from the
aforesaid side wall 4a, maintaining the constant distance from the lower surface of
the roller 3. Namely, the gap (the distance between the lower surface of the roller
3 and the member 5) of toner conveying area A₁, where the aforesaid toner-spill-prevention
member 5 covers the lower surface of roller 3, is smaller than the height of carrier
brush H. Therefore, the brush H in the toner conveying area A₁ functions as a stopper
that prevents toner T from flowing down (Fig. 3). The lower end portion of toner-spill-prevention
member 5 is almost horizontal and it receives the toner which have passed through
the brush H and the toner which have left the toner replenishing roller 3, thus preventing
the toner dropping. The aforesaid toner-spill-prevention member 5 may either be formed
to be of a one body with aforesaid side wall 4a at toner outlet side, or be a separate
member to be attached
[0017] Incidentally, toner-spill-prevention member 5 may further be a flexible film protruding
from the side wall 4a at toner outlet side on opening 4 and contacting lightly the
lower surface of the roller 3 as shown in Fig. 4.
[0018] Aforesaid carrier brush height regulating member 6 is for regulating the height of
carrier brush entering the toner contact area A₀ (lower portion of toner replenishing
room including toner conveying area A₁) and is made of a shelf- formed member that
extends toward roller 3 from side wall 4 facing the toner-spill-prevention member
5 on the aforesaid opening 4. The edge of the regulating member 6 touches, in the
opening area A₂ spanning from the lower edge of the toner-spill-prevention member
5 to the regulating member 6, the tip of the brush H formed on the roller 3 when carriers
are additionally attracted magnetically from the side of developer agitating chamber
12, thus it is possible to regulate the tip of the brush. The gap between the regulating
member 6 and roller 3 is determined by a number of factors such as the magnetic adsorption
intensity of roller 3 and the particle size of carrier C; however, it is usually preferable
that the gap is about 70% - 90% of the height of brush H.
[0019] Incidentally, aforesaid toner replenishing room 2 and main supplying chamber 11 are
unified solidly into a unit in one piece and the unit is detachable at joint line
S from developing unit 10, which means that the unit can be removed from copying machine
100 on the occasion of maintenance or the like.
[0020] Aforesaid developer agitating chamber 12 is provided therein with an auxiliary agitating
roller r and a principal agitating roller R. The auxiliary agitating roller r is located
on the side of paper feeding section so that it may convey to the principal agitating
roller R the developer comprising toner T supplied from toner supplying room 2 and
carrier C both supplementally-mixed. The principal agitating roller R is located adjacently
to the aforesaid developing roller 13 and it further mixes thereunder the developer
supplied from auxiliary agitating roller r and supplies the developer to developing
roller 13, and concurrently agitates thereon the developer which has become carrier-rich
after discharging its toner T toward the vicinity of the opening area A₂ for the aforesaid
replenishing roller 3, thus supplementing the formation of a brush.
[0021] The numeral 17 is a detection sensor for the toner concentration and it is located
at the proper position in the vicinity of auxiliary agitating roller r so that it
may detect the toner concentration based on the change in inductance of developer
running in the neighborhood of auxiliary agitating roller r. It is arranged so that
the toner concentration can be detected based on the change of the magnetic permeability
of a developer. The numeral 18 is a flow-qauntity-regulating plate and it is for dividing
the flow in developer agitating chamber 12 into the lower flow layer (the layer between
auxiliary agitating roller r and the bottom side of principal agitating roller R)
and the upper flow layer (the layer between the upper side of principal agitating
roller R and the portion directly under toner replenishing room 2). The flow-regulating
plate is made of an L-shaped member provided mostly at the center between roller r
and roller R.
[0022] Aforesaid photoreceptor drum 14 is arranged so that it can rotate, being linked with
and contacting to the aforesaid developing roller 13, thus an electrostatic latent
image is formed on the photoreceptor drum by the light from aforesaid exposure section
20, and toner T from developing roller 13 is adsorbed to the electrostatic latent
image to form a toner image; further, the toner image is transferred onto the image-transfer
paper.
[0023] Toner T dropped from toner cartridge 15, after being stored on the bottom 11a of
main supplying chamber 11, is transported by toner conveying member 16 and fed into
toner replenishing room 2 of main body 1 through inlet 2a. When toner replenishing
roller 3 of a magnet type rotates, the brush H conveys toner T through toner transport
area A₁ and feeds it to developer agitating chamber 12 through the lower opening 4.
In this case, the height of brush H is regulated suitably by brush height regulating
member 6, and toner T not scooped by brush H is supported by toner-spill-prevention
member 5. Further, toner T enters the brush H diffusively, resulting in a preliminary
mixture of toner T and carrier C, which prevents in advance the generation of small
toner lumps.
[0024] After toner T and carrier C are mixed uniformly by auxiliary agitating roller r and
principal agitating roller R in developer agitating chamber 12, the toner is transferred
to photoreceptor drum 14 by developing roller 13.
[0025] In the exposure section 20, light emitted from light source 24 located on carriage
25 is reflected on a document placed on platen glass 21, and arrives, through reflection
mirrors 26a, 26b, 26c and 26d, at photoreceptor drum 14 where there is formed an electrostatic
latent image which then adsorbs toner T to form a toner image. The toner image is
transferred on an image-transfer paper fed from paper feeding unit 30 at transfer/separation
unit 60 and then fixed by the fixing roller of fixing unit 40 onto the image-transfer
paper which is then ejected from paper ejecting unit 50.
[0026] The present invention enables toner in the toner replenishing room to be conveyed
by the carrier brush while the toner and carrier are mixed in advance, because the
invention is characterized in that a toner replenishing roller on which N-poles and
S-poles are magnetized one after the other along its circumference is provided at
the lower opening of a toner replenishing room that replenishes toners into two-component
developer agitating chamber, and that a toner-spill-prevention member is provided
on the toner outlet side at the aforesaid opening and a carrier brush height regulating
member is provided on the side opposite to the aforesaid toner outlet side. Further,
the toner failed to be conveyed by the carrier brush in the toner replenishing room
is stopped by the toner-spill-prevention member and thereby do not drop into the developer
agitating chamber, and adjustment of toner conveyance and preliminary mixing can be
made by controlling the height of the brush height regulating member.
[0027] As a result, there is no fear that toner clods are produced in the toner agitating
chamber despite an arrangement that a toner replenishing room is provided over a developer
agitating chamber, thus it is possible to achieve the uniform mixing and stability
of developer, which results in an excellent effect of an improvement of quality of
a copied image.
[0028] A preferable embodiment of a toner replenishing device of a magnet roller type stated
above will be explained as follows.
[0029] In this magnet roller type replenishing device, a carrier brush scrapes the inner
surface of a replenishing room to convey toners, and there is a risk that a part of
the carrier brush falls off, when it scrapes and stays in the replenishing room (Fig.
6). When this carrier stays at the toner outlet of the opening and forms a 'carrier
clod', it adversely affects the toner flow, causing the fear that the condition close
to the idle running of the roller will be generated.
[0030] In the light of the aforesaid point, an object of the example is to provide a toner
replenishing device which is of a magnet roller type and yet does not cause a risk
of the generation of a 'carrier clod'.
[0031] In order to achieve the aforesaid object in the toner replenishing device of the
invention, a toner replenishing roller whose circumference is furnished with S-poles
and N-poles magnetized thereon one after the other is provided at the lower opening
of the toner replenishing room that replenishes toners into a two-component developer
agitating chamber, a toner-spill-prevention member is provided on the toner outlet
side at the aforesaid opening, and a carrier brush height regulating member is provided
on the side opposite to the aforesaid toner outlet side; and the distance between
the aforesaid brush height regulating member and the replenishing roller is made to
be smaller than that between the aforesaid toner-spill-prevention member and the replenishing
roller and the height of the carrier brush is controlled so that no carrier may fall
off in the toner replenishing chamber.
[0032] Namely, as shown in Fig. 6, the distance t₂ between the aforesaid regulating member
6 and the roller 3 is arranged against the distance t₁ between the aforesaid toner-spill-
prevention member 5 and the lower side of the roller so that they satisfy the following
relation,
t₂ < t₁
and thereby it may be prevented that the tip of the brush H regulated by the distance
t₂ hits the side wall 4a at toner outlet side or hits the toner-spill-prevention member
5 and thereby carriers come off, resulting in the generation of carrier stay.
[0033] An embodiment wherein the device is suspended will be explained as follows. In the
magnet roller type replenishing device, a carrier brush scrapes the inner surface
of the toner replenishing room for conveying toner, and when the unit composed of
the toner replenishing room and the main supplying chamber is removed with the replenishing
roller suspended, on the occasion of the replacement of a toner cartridge, and when
the brush-forming at the opening area (an area spanning from the edge of the toner-spill-prevention
member to the brush height regulating member) is suspended, there is a risk that toners
held by the brush may drop and scatter.
[0034] In the light of the aforesaid point taken into consideration, an object of the example
is to provide a toner replenishing device wherein the carrier brush can not be located
at an area of the opening when the replenishing roller stops running.
[0035] In order to achieve the aforesaid object, the toner replenishing device of the example
wherein the replenishing roller whose circumference is furnished thereon with N-poles
and S-poles magnetized one after the other is provided at the lower opening of the
toner replenishing room that replenishes toners into a two-component developer agitating
chamber, a toner-spill-prevention member in a gutter form having a curved surface
along the lower face of the toner replenishing roller at a constant interval is provided
at the toner outlet side of the aforesaid opening and a carrier brush height regulating
member is provided on the opposite side, is arranged not to cause the carrier brush
to stop in the area of the opening, by the arrangement wherein the central angle ϑ,
of the opening area spanning from the edge of the toner-spill-prevention member to
the brush height regulating member, satisfies the following relation with the number
of magnetic poles on the aforesaid toner replenishing roller,
ϑ < 360°/p
and a roller stopping means that stops the magnetic pole within a toner contact zone
other than the aforesaid opening area is provided.
[0036] In Fig. 7, the numeral 7 is a roller-stopping means for stopping at the prescribed
angular position the brush H formed in the position of a magnetic pole on the aforesaid
toner replenishing roller 3 and it comprises driving gear 7a, partially-toothed gear
7b, transmission gear 7c, reduction gear 7d, replenishing-driving gear 7e, spring
8, solenoid 9, catch lever 9a and positioning cam I. A gear train comprising driving
gear 7a, partially-non-toothed gear 7b, transmission gear 7c, reduction gear 7d and
replenishing-driving gear 7e transmits torque in that sequence, and the replenishing-driving
gear 7e rotates toner replenishing roller 3.
[0037] The solenoid 9 is switched ON and OFF in response to a signal from control means
for controlling the toner density and RUN/STOP of the copy nachine, therely the solenoid
regulates transmition of torque with the work of the catch lever 9a. As shown in Fig.
7 (b), the gear surface of the partially-non-toothed gear 7b consists of a gear portion
engaged with the driving gear 7a and a gear portion engaged with the transmission
gear 7c. For the purpose that the toner replenishing roller 3 rotates by the prscribed
angle which corresponds to the number of poles p on the toner replenishing roller,
in the gear portion engaged with the driving gear 7a on the partially-non-toothed
gear 7b there is provided a not-toothed angular area. Aforesaid positioning cam I
is for driving and controlling the partially-non-toothed gear 7b and its radius varies
continuously along its entire circumference from the smallest radius to the largest
one where it has a step d whose height equals the difference between the smallest
radius and the largest one, and it is attached, in a coaxial manner, on the side of
partially-non-toothed gear 7b. By means of solenoid 9, the aforesaid catch lever
9a catches or releases the step d on the cam I, resulting in the ON/OFF of the torque
transmission between driving gear 7a and partially-non-toothed gear 7b. The spring
8 controls, through the cam I, each rotation of the partially-non-toothed gear 7b
and its one end is hooked on the fixed portion on copying machine 100 and the other
end is hooked on pin 8a (not coaxial with cam I) provided at a proper position (opposite
to partially-toothed gear 7b side) on the side of the cam I. The spring 8, when the
step d is released from the aforesaid catch lever 9a, energizes the partially-non-toothed
gear 7b to mesh with the driving gear 7a to transmit the driving torque, therely the
replenishing-driving gear 7e is rotated. While, when the non-toothed area of partially-non-toothed
gear 7b arrives at the engagement portion of driving gear 7a after the replenishing-driving
gear 7e has rotated by the predetermined angles and torque transmission is thereby
suspended, the spring 8 continues energizing the partially-non-toothed gear 7b. And
then, the step d on the cam is caught by the catch lever 9a, therely the replenishing-driving
gear 7e is kept at its stop position. Therefore, the ON/OFF operation of solenoid
9a controls each rotation of partially-non-toothed gear 7b, thus, the toner replenishing
roller 3 that is linked with partially-non-toothed gear 7b can rotate intermittently
by, for example, 90 degrees or 45 degrees.
[0038] Incidentally, the roller-stopping means 7 may be a driving system which can control
digitally the angular position of toner replenishing roller 3. In this case, the toner
replenishing roller 3 may be rotated either in the system wherein it rotates by the
angle of 360 degrees/p (number of poles) similarly to the aforesaid partially-non-toothed
gear driving system, or in the feedback system wherein an appropriate sensor (a magnetic
sensor or a rotary encoder) detects the magnetic pole on the toner replenishing roller
3 and thereby stops it at desired angular position. As stated above, the opening area
A₂ is determined so that the relation between its central angle ϑ and the number of
poles on the aforesaid toner replenishing roller 3 may satisfy the inequality below.
ϑ < 360°/p
[0039] When stopping the toner replenishing roller 3 by the aforesaid roller-stopping means
7, it is so arranged that the brush H formed at the position of a pole stops other
than the opening area A₂, but only within toner contact area A₀. Therefore, at least
one of brushes H surely contacts the toner-spill-prevention member in the toner conveyance
area, and thereby functions as a 'stopper' which prevents toner dropping in advance.
Further, when step d is released from catch lever 9a by solenoid 9 in roller-stopping
means 7, the spring 8 energizes the partially-non-toothed gear 7b to rotate and further
to mesh with driving gear 7a for the transmission of torque. The number of teeth of
the partially-non-toothed gear 7b is determined so that it corresponds to the rotating
angle of toner replenishing roller 3 that is rotated through reduction gear 7d and
replenishing-driving gear 7e. Therefore, when the catch lever 9a catches the step
d and thereby the rotation of partially-non-toothed gear 7b is stopped, the magnetic
pole stops surely at the prescribed angular position.
[0040] In the roller-stopping means 7, when the number of teeth of each gear is set in the
combinations of Example 1 and Example 2 shown in Table 1, the intermittent rotation
angle are 90° and 45° respectively. In these cases, it is possible to create the condition
wherein no brush H is formed in opening area A₂ because the central angle ϑ is smaller
than 360°/p. Further, it is arranged so that all poles of toner replenishing roller
3 stop within toner contact area A₀ which is out of the aforesaid opening area A₂.
Table 1
Example of arrangement of roller-stopping means |
Symbol |
Gear name |
Number of teeth |
Number of teeth |
|
|
(Example 1) |
(Example 2) |
7a |
Driving gear |
30 |
Ditto |
7b |
Partially-non-toothed gear |
(24) |
Ditto |
7c |
Transmission gear |
40 |
Ditto |
7d |
Reduction gear (1/2) |
20 |
Ditto |
7e |
Replenishing-driving gear |
48 |
96 |
[0041] Incidentally, in the toner conveyance area A₁, toner T not held by brush H is prevented
from dropping by toner-spill-prevention member 5. As stated above, on the aforesaid
toner replenishing device in the present example, the relation between the central
angle ϑ, of the opening area spanning from the edge of the aforesaid toner-spill-prevention
member to the brush height regulating member, and the number of poles p of the aforesaid
toner replenishing roller satisfies the following inequality,
ϑ < 360°/p
and the toner replenishing device is characterized in that a roller-stopping means
that stops the poles of the aforesaid toner replenishing roller within a toner contact
area other than the aforesaid opening area is provided. Therefore, when the roller
stops, brushes never be positioned within the opening area.
[0042] Therefore, even if the toner replenishing roller is exposed in the case of a cartridge
replacement, or of a maintenance, which are performed with carrier brushes conveying
toners in a large amount; there hardly is a risk of toner dropping or scattering,
resulting in an excellent effect that both toner conveyance efficiency and work efficiency
are improved.