U.S. patent number 3,650,196 [Application Number 04/868,791] was granted by the patent office on 1972-03-21 for device for automatically regulating the concentration of developing solution.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Kazuya Hosoe, Yoshimasa Kimura.
United States Patent |
3,650,196 |
Hosoe , et al. |
March 21, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
DEVICE FOR AUTOMATICALLY REGULATING THE CONCENTRATION OF DEVELOPING
SOLUTION
Abstract
A device for automatically regulating the concentration of a
developing solution, consisting of toner dispersed in a carrier
solution, maintains developing solution having a predetermined
concentration in a wet type developing device. The concentration of
the solution is photoelectrically detected, and, when the
concentration decreases to less than the predetermined valve
concentrated toner from a container is supplied by negative
pressure generated by the falling of developing solution then
remaining in a concentration regulating device into a developing
solution reservoir under the action of gravity. Such concentration
adjustment occurs in response to the interruption of the
circulation of the solution and disconnection of the concentration
regulating device from the surrounding atmosphere.
Inventors: |
Hosoe; Kazuya (Tokyo,
JA), Kimura; Yoshimasa (Tokyo, JA) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JA)
|
Family
ID: |
13727912 |
Appl.
No.: |
04/868,791 |
Filed: |
October 23, 1969 |
Foreign Application Priority Data
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Nov 5, 1968 [JA] |
|
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43/80779 |
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Current U.S.
Class: |
399/30; 118/691;
399/237; 399/64; 399/62; 399/57; 399/259; 137/93 |
Current CPC
Class: |
G03G
15/105 (20130101); G05D 21/02 (20130101); Y10T
137/2509 (20150401) |
Current International
Class: |
G05D
21/00 (20060101); G03G 15/10 (20060101); G05D
21/02 (20060101); G03d 003/00 () |
Field of
Search: |
;355/10 ;95/89
;118/637XL,9 ;117/37XL |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Matthews; Samuel S.
Assistant Examiner: Sheer; Richard M.
Claims
What is claimed is:
1. An automatic developing solution concentration regulating device
comprising:
a developing solution reservoir;
a developing solution concentration regulating means in
communication with the surrounding atmosphere;
a toner concentrate storage container;
means for circulating the developing solution between said
developing solution reservoir and said developing solution
concentration regulating means when the concentration of the
developing solution is higher than a predetermined value;
means for detecting the concentration of the developing
solution;
means for interrupting the circulation of the developing solution
through said concentration regulating means when the concentration
of the developing solution decreases to less than said
predetermined value;
means for disconnecting the communication of said concentration
regulating means with the surrounding atmosphere; and
means for supplying toner concentrate from said toner concentrate
storage container to said concentration regulating means only upon
the decreasing pressure generated by the falling of the developing
solution remaining in said concentration regulating means into said
developing solution reservoir under the action of gravity in
response to said interruption of the circulation of the developing
solution and said disconnection of said communication of said
concentration regulating means with the surrounding atmosphere.
2. The automatic developing solution concentration regulating
device claimed in claim 1 wherein said means for detecting the
concentration of the developing solution is a photoelectric means
providing electrical signals indicative of variations in intensity
of light emitted from a light source due to the variations in
concentration of the developing solution.
3. The automatic developing solution concentration regulating
device claimed in claim 1 including
means for concurrently actuating said means for interrupting the
circulation of the developing solution through said concentration
regulating means and said means for disconnecting the communication
of said concentration regulating means with the surrounding
atmosphere when the concentration of the developing solution
decreases to less than said predetermined value.
4. The automatic developing solution concentration regulating
device claimed in claim 1 wherein
said means for supplying toner concentrate from said toner
concentrate storage container to said concentration regulating
means is a siphon.
5. The automatic developing solution concentration regulating
device claimed in claim 2 including an electromagnet and means for
energizing said electromagnet where said signals indicate a
decrease of the concentration of the developing solution to below
said predetermined value, said electromagnet concurrently actuating
said means for interrupting the circulation of the developing
solution through said concentration regulating means and said means
for disconnecting the communication of said concentration
regulating means with the surrounding atmosphere.
6. An automatic developing solution concentration regulating device
comprising:
a developing device;
a developing solution reservoir;
developing solution concentration regulating means in communication
with the surrounding atmosphere;
a toner concentrate storage container;
means for circulating the developing solution between said
developing solution reservoir and said developing device;
means for circulating the developer solution between said reservoir
and said developing solution concentration regulating means when
the concentration of the developing solution is higher than a
predetermined value;
means for detecting the concentration of the developing
solution;
means for interrupting the circulation of the developing solution
through said concentration regulating means when the concentration
of the developing solution decreases to less than said
predetermined value;
means for disconnecting the communication of said concentration
regulating means with the surrounding atmosphere; and
means for supplying toner concentrate from said toner concentrate
storage container to said concentration regulating means only upon
the decreasing pressure generated by the falling of the developing
solution remaining in said concentration regulating means into said
developing solution reservoir under the action of gravity in
response to said interruption of the circulation of the developing
solution and said disconnection of said communication of said
concentration regulating means with the surrounding atmosphere.
7. The automatic developing solution concentration regulating
device claimed in claim 6, wherein said means for detecting the
concentration of the developing solution is disposed in said
developing solution concentration regulating means.
8. Apparatus for use in maintaining a predetermined concentration
of toner in developing solution contained in a reservoir,
comprising:
a vessel containing concentrated toner and having a first port
communicating with ambient atmosphere and a second port;
a tank having a top wall disposed vertically above the level of
toner in said vessel and including a first tank port and a second
tank port, a bottom wall providing a third tank port disposed
vertically below said toner level and a side wall including a
fourth tank port;
toner supply means sealably connecting said vessel second port and
said tank second port and extending into said vessel below said
toner level;
developing solution circulating means comprising a pump disposed in
said reservoir, a first valve in said tank, a first conduit
extending from said pump to said first valve, and a second conduit
extending from said first valve to said reservoir;
a second valve connecting said first tank port to ambient
atmosphere;
means for detecting the concentration of toner in developing
solution in said tank; and
circuit means responsive to said detecting means for actuating said
first and second valves to first positions to provide communication
respectively between said first conduit and said tank and between
said tank first port and ambient atmosphere when detected toner
concentration is greater than said predetermined concentration and
for actuating said first and second valves respectively to second
positions to provide communication between said first conduit and
said second conduit and to discontinue communication between said
tank first port and ambient atmosphere when detected toner
concentration is less than said predetermined concentration.
Description
The present invention generally relates to electrophotographic
devices and particularly to a wet type developing device used in
electrophotographic devices. More specifically, the present
invention relates to an automatic developing solution concentration
regulating device for use with wet type developing devices.
In electrophotographic processes, the developing solution,
consisting of toner dispersed in a carrier solution, is applied to
the exposed surface of a photosensitive element for developing an
electrostatic latent image formed thereupon. The toner particles
are attracted to and held upon the surface of the photosensitive
element in correspondence with the pattern of the latent image by
electrostatic force. Such developed electrophotographic toner image
is fused upon the photosensitive element by fixing means, such as a
heater. Alternately, the developed image may be transferred to and
fused upon a suitable recording element such as a paper sheet. In
the wet type developing method used in the electrophotographic
process, toner concentration is decreased as the developing
operations are repeated and the concentration of the developing
solution must be maintained at a predetermined value so as to
enable the production of copies having high quality images without
any irregular adhesion or attraction of the toner particles. As
described above, the developing solution consists of two
components, the toner particles and a carrier solution. The toner
particles will be consumed, as described above, so that the
concentration of the developing solution, that is, the
concentration of the toner particles therein, must be detected and
toner supplied for maintaining a predetermined concentration during
the developing operation.
In the conventional automatic concentration regulating device for
use with wet-type developing devices for electrophotography, the
concentration of the developing solution is photoelectrically
detected and toner concentrate is supplied or added to the
developing solution from a concentrated toner storage container
depending upon the detected concentration. For example, toner
concentrate is added to the developing solution from an inverted
concentrated toner storage container by opening and closing the
toner supply opening thereof, thereby dropping the toner
concentrate into the developing solution. In this case, it is very
difficult to add the toner concentrate in exact quantity in
response to detected concentration and, in some cases, there is the
possibility that toner concentrate may be forced into the
developing solution because of thermal expansion of air inside the
storage container. There has been proposed another method in which
the concentrated toner storage container is arranged upright and
air under pressure is forced into the container through an air port
formed in the upper portion thereof, thereby forcing the toner
concentrate out of the container through a toner concentrate supply
port formed also in the upper portion thereof. In this case, it is
also very difficult to add the toner concentrate in exact quantity.
Furthermore, an air pump must be provided for introducing air under
pressure into the storage container and the device must be designed
to operate with a high degree of accuracy, thus resulting in high
manufacturing cost. In still another method an air port and a toner
concentrate supply port are formed in the upper portion of a
concentrated toner storage container and a pump is provided to pump
toner concentrate therefrom. However, it is also difficult to add
the toner concentrate in exact quantity and there is the
possibility that the pump and its piping may become clogged with
toner particles.
The primary object of the present invention is to provide an
automatic developing solution concentration regulating device which
can constantly supply developing solution having a predetermined
concentration to a wet type developing device.
Another object of the present invention is to provide an improved
automatic developing solution concentration regulating device which
can detect the toner concentration and constantly maintain it at a
predetermined value by supplying toner concentrate or the like
depending upon detected concentration.
A further object of the present invention is to provide an improved
automatic developing solution concentration regulating device which
can positively circulate developing solution between a developing
solution reservoir and a developing solution container (in a
developing device) by use of a pump.
A still further object of the present invention is to provide an
improved automatic developing solution concentration regulating
device which can effect its whole operations automatically with a
high degree of accuracy based upon static hydrodynamic
principles.
The above and other objects, features and advantages of the present
invention will become more apparent from the following description
of one illustrative embodiment thereof taken in conjunction with
accompanying drawing, in which:
FIG. 1 is a longitudinal sectional view of one embodiment of an
automatic developing solution concentration regulating device in
accordance with the present invention; and
FIG. 2 is a circuit diagram of a developing solution concentration
detecting device used therein.
Referring to FIG. 1, within a developing solution reservoir 1 is
contained a developing solution, consisting of toner dispersed in a
carrier solution, and a developing solution circulating pump 3 is
disposed securely in position within the developing solution
reservoir 1 below the level of the developing solution therein. At
the bottom of the circulation pump 3 is formed an aperture or port
4 for the suction of the developing solution therein and two pipes
or ducts 5 and 6 for supplying the developing solution extend
upwardly from the upper portion of the circulation pump 3. The pipe
5 is adapted to supply the developing solution into a developing
solution tank 8 or the like disposed within a developing device 7,
from which the developing solution may be returned to the reservoir
1. The pipe 6 communicates with a developing solution concentration
regulating tank 9 so that the developing solution discharged from
the circulation pump 3 is circulated through the pipe 6, the
regulating tank 9, a discharge pipe 10 extending downwardly from
the regulating tank 9 to the developing solution reservoir 1.
Preferably, the lower open end of the discharge pipe 10 is slightly
above the level of the developing solution in the solution
reservoir 1 so that the level, that is the volume of the developing
solution in the developing solution reservoir 1, may be determined
depending upon the position of the lower open end of the discharge
pipe 10.
Within the developing solution concentration regulating tank 9 is
disposed a photoelectric transducer means 13 consisting of a light
source 11, connected to a supply E by a switch S, and a
photoconductor element 12. When the concentration of the developing
solution rises above a predetermined value, the developing solution
is circulated from the reservoir 1 through the circulation pump 3,
the developing solution concentration regulating tank 9 and the
discharge pipe 10 to the reservoir 1 again. On the other hand, when
the concentration of the developing solution falls below the
predetermined value, signals indicating this decrease in
concentration of the developing solution and generated by the
photoelectric transducer means are transmitted to an electromagnet
14 disposed above the concentration regulating tank 9, thereby
energizing this electromagnet 14 so as to close a valve 16 in a
pipe 15, connected between the concentration tank and the
surrounding atmosphere and to close a valve 17 between the duct 6
and the concentration regulating tank 9, thereby opening a
circulation pipe 18.
The head between the normal level of the solution within the
concentration regulating tank 9 and the lower opening end of the
discharge pipe 10 is designated by H.sub.1. The head between the
average height designated by the line A-B connecting the vertices
of a siphon 20 intercommunicating the concentration regulating tank
9 and a toner storage tank 19 and the level of the toner solution
within the toner storage tank 19 is designated by H.sub.2. The head
between the upper wall of the concentration regulating tank 9 and
the above described line A-B is designated by H.sub.3. In this
case, it should be noted that the parts of the device of the
present invention are so arranged that the following relation will
be held:
H.sub.1 > H.sub.2 > H.sub.3.
Therefore, the developing solution present in the concentration
regulating tank 9 flows down into the developing solution reservoir
1 through the discharge pipe 10 by the action of gravity of head
H.sub.1 so that a negative pressure is produced in the
concentration regulating tank 9. Thus, because of the relation:
H.sub.1 > H.sub.2 the toner concentrate within the toner storage
tank 19 is forced into the concentration regulating tank 9 through
the siphon 20, whose bottom end is disposed in closely spaced apart
relation with the bottom of the toner storage tank 19, which is
hermetically closed except for a vent 21 in the cover thereof. When
the toner solution is supplied into the concentration regulating
tank 9 in the manner as described hereinabove, the pressure within
the tank 9 is increased and the toner solution is mixed with the
developing solution. Thereafter, the mixed developing solution
flows into the reservoir 1. Thus, it is seen that when the above
described steps occur, the concentration of the developing solution
may gradually approach a predetermined value. When the developing
solution concentration reaches such predetermined value, the
photoelectric means is deenergized and the electromagnet 14 is also
deenergized thereby returning the valves 16 and 17 to their normal
positions. In this case, it should be noted that the flow of the
toner solution from the toner storage tank 19 through the siphon 20
stops 4432>H.sub.3.
Next referring to FIG. 2, when the concentration of the developing
solution is above the predetermined value, the light emitted by the
light source 11 will not be incident upon the photoconductor
element 12, such as CdS, and the element because of the
relation:
H.sub.2 > has a 3. resistance, as is well known in the art.
Therefore, in the transistorized balancing circuit, the potentials
at the points A and B are substantially equal. Since the
transistors Tr.sub.1 and Tr.sub.2 are temperature-responsive, that
is their characteristics are easily susceptible to variations due
to temperature change, a thermistor Th is interconnected, thereby
compensating for the variation due to the temperature change. When
the concentration of the developing solution drops below the
predetermined level, the light from the light source 11 is incident
upon the element 12 so that its resistance is decreased.
Consequently, the current flowing from the point A into the
transistor Tr.sub.1 and the resistor r.sub.3 is decreased and
current flows from the point C through the transistor Tr.sub.3 and
a resistor 5 into the transistor Tr.sub.2 and the resistor r.sub.3.
Furthermore, current flows through the electromagnet 14 and the
transistor Tr.sub.3 so that the electromagnet 14 is energized,
thereby closing the valve 17 so as to close the passage 23 between
the pipe 6 and the concentrating regulating tank 9 while opening
the circulation pipe 18. An armature 22 is attracted by the
electromagnet 14 so that the valve 16 closes the pipe 15 thereby
interrupting the interior of the concentration regulating tank 9
and the surrounding atmosphere.
In the instant embodiment shown in FIG. 1, the photoelectric means
13 has been described as being disposed within the concentration
regulating tank 9, but it is understood that it may be disposed
within the developing solution reservoir 1 or the developing device
7 as desired.
From the foregoing, it will be understood that the present
invention is based upon static hydraulics principles, in which the
concentration of the developing solution circulating between the
developing device and the developing solution reservoir is
photoelectrically detected so that when the concentration falls
below a predetermined value, normal circulation of the developing
solution is stopped and toner solution is supplied from a
concentrated toner storage container into the concentration
regulating tank under the influence of the negative pressure
produced therein due to gravity flowdown of the developing solution
remaining in the tank 9. Thus devices in accordance with the
present invention are very simple in construction yet highly
reliable in operation for supplying and constantly maintaining the
concentration of the developing solution at a predetermined value
because the toner concentrate may be supplied in exact quantity to
maintain the concentration of the developing solution at the
predetermined value. Therefore, better quality copies may be
continually provided.
* * * * *