U.S. patent number 3,677,222 [Application Number 05/005,794] was granted by the patent office on 1972-07-18 for device for automatically regulating the concentration of developing solution.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Hiroyuki Hattori, Shigehiro Komori.
United States Patent |
3,677,222 |
Komori , et al. |
July 18, 1972 |
DEVICE FOR AUTOMATICALLY REGULATING THE CONCENTRATION OF DEVELOPING
SOLUTION
Abstract
Device for automatically regulating the concentration of
developing solution in a wet type electrophotographic machine.
Stirrer means is used to stir the developing solution for
circulation through a developing tray and a reservoir, and a
concentration detector is disposed in the stream of developing
solution. The concentration detector has a source of radiation such
as light and two elements sensitive to the radiation and the
detection circuit including two elements. The concentration
detector provided within the stream can effect the regulation of
concentration with high accuracy and stability.
Inventors: |
Komori; Shigehiro
(Kawasaki-shi, JA), Hattori; Hiroyuki (Tokyo,
JA) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JA)
|
Family
ID: |
11924790 |
Appl.
No.: |
05/005,794 |
Filed: |
January 26, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Feb 24, 1969 [JA] |
|
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44/16745 |
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Current U.S.
Class: |
399/30; 399/237;
399/62; 399/57 |
Current CPC
Class: |
G03G
15/105 (20130101); G05D 21/02 (20130101) |
Current International
Class: |
G05D
21/00 (20060101); G03G 15/10 (20060101); G05D
21/02 (20060101); G03g 013/08 () |
Field of
Search: |
;118/7,637
;117/17.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Jaudon; Henry S.
Claims
What is claimed is:
1. A device for automatically regulating the concentration of
developing solution in a wet type electrophotographic machine which
comprises:
a reservoir for said developing solution;
a developing tray in fluid connection with said reservoir;
means for detecting the concentration of said developing solution
disposed in said reservoir, said detecting means including a source
of radiation and means sensitive to said radiation arranged to
produce a signal upon changes in the concentration of said
solution; and
means for supplying concentrated developing solution operable in
response to said signal from said detecting means.
2. The device of claim 1 which further includes stirring means
arranged in said reservoir to maintain circulation of said solution
through said developing tray and reservoir.
3. The device of claim 1 wherein said means sensitive to said
radiation comprises at least two elements sensitive to radiation,
one of said elements being disposed at one side of said source of
radiation with the developing solution flowable therebetween and
said second element being disposed at the other side of said source
of radiation with means for regulating said radiation interposed
therebetween, said elements being in circuit to produce said
signal, and said detection means further includes a switching
circuit activated by said signal to operate said supply means.
4. The device of claim 3, wherein said means for regulating said
radiation comprises a plate defining a predetermined sized
slit.
5. A device for automatically regulating the concentration of a
developing solution as defined in claim 3 wherein said detecting
means is contained in a casing having a radiation passage formed of
a light transmitting material through which said developing
solution flows.
6. A device for automatically regulating the concentration of a
developing solution in a wet type developing machine for
electronically picked-up images, said device comprising a
reservoir, a developing tray, means for stirring the developing
solution in said reservoir, means for detecting the concentration
of said developing solution disposed in the flow passage of said
developing solution, and means for supplying concentrated solution
to said reservoir, said means for detecting the concentration of a
developing solution having a switching circuit including a
detection circuit having a source of radiation and at least two
elements sensitive to the radiation from said source of radiation,
one of said elements being disposed at one side of said source of
radiation with the developing solution flowing therebetween, the
other element being disposed at the other side of said source of
radiation with means for regulating the quantity of radiation
interposed therebetween, said means for supplying concentrated
solution actuating a plunger and a valve rod in response to the
output of said means for detecting the concentration of the
developing solution so as to actuate valves located in a discharge
port of a supply of concentrated solution for supplying a
predetermined amount of concentrated solution into said reservoir.
Description
This invention relates to a wet electrophotographic machine, and
more particularly to a device for automatically regulating the
concentration of a developing solution used with such a
machine.
In a wet type electrophotographic machine, it is important to
automatically maintain the concentration of a developing solution
at a predetermined level in order to prevent the uneveness of the
resultant image and provide an excellent quality of the image as
well as to simplify the manipulation of the machine.
There are the following two methods of detecting the concentration
of the developing solution in a wet type electrophotographic
machine and supplying concentrated developer from an auxiliary tank
in accordance with the detection signal.
1. Concentrated liquid is continuously supplied from the auxiliary
tank when the means for detecting the concentration of the
developing solution is producing a signal representing an
insufficient concentration.
2. A predetermined amount of concentrated liquid is supplied once
or more from the auxiliary tank when the means for detecting the
concentration of the developing solution is producing a signal
representing an insufficient concentration.
While the present invention may be applicable to both of the
foregoing methods, a description will now be made briefly with
respect to the application of the invention to the second method
mentioned above.
Stirrer means is provided to stir the developing solution for
circulation through a developing tray and a reservoir and there is
disposed a concentration detector in the stream of the developing
solution. The concentration detector comprises a source of
radiation, and elements sensitive to said source of radiation and
disposed at both sides thereof and a detection circuit including
these elements. Between the source of radiation and one of the
elements sensitive thereto the developing solution is introduced
and circulated. Between the source of radiation and the other
element sensitive thereto there is interposed means for regulating
the quantity of light so that equal quantities of light reach the
two elements when the developing solution in the reservoir has a
standard or proper concentration. The detection circuit is in a
balanced state when the developing solution has the standard
concentration. If the concentration of the developing solution is
decreased, a switching circuit including the detection circuit is
operated to actuate a plunger and associated valves of an auxiliary
tank so that a predetermined amount of concentrated liquid is
supplied from the auxiliary tank through its valves into the
reservoir to increase the concentration of the developing solution
therein to the standard level.
In contrast, according to the prior art, the concentration detector
is disposed exteriorly of the developing machine and this
arrangement requires the provision of means such as a pipe or the
like for introducing the developing solution into the concentration
detector. Such means presupposes a space therefor which results in
a larger size and higher cost of the entire device. Furthermore,
the measurement of concentration is not effected directly with the
developing solution circulating in the reservoir but with a portion
of it which is introduced through the pipe or like means, and this
results in a lower accuracy of the measurement.
It is an object of the present invention to provide a device for
automatically regulating the concentration of a developing solution
by means of a concentration detector disposed directly in the path
of the developing solution circulating in a developing tray or a
reservoir to effect the regulation of the concentration with high
accuracy and stability.
It is another object of the present invention to provide a less
expensive device for automatically regulating the concentration of
a developing solution which has a concentration detector disposed
in a developing tray or a reservoir thereby eliminating the need to
provide any additional space for such detector and the need to use
any additional means such as pipe or the like required by the prior
art.
The invention will now be described in greater detail with respect
to an embodiment thereof shown in the accompanying drawings, in
which:
FIG. 1 is a partly broken-away perspective view of a wet type
developing machine incorporating the device of the present
invention;
FIG. 2 is a plan view of the machine shown in FIG. 1;
FIG. 3 is a sectional view taken along line III--III of FIG. 2;
FIG. 4 is a cross-sectional view taken along line IV--IV of FIG.
2;
FIG. 5 is a front view, in vertical section, of the detector
portion for detecting the concentration of the developer;
FIG. 6 is a front view, in vertical section, of the valve portion
for supplying concentrated liquid; and
FIG. 7 diagrammatically shows the electric circuit for detecting
the concentration of the developing solution.
Referring to FIGS. 1 to 4, a reservoir 1 contains therein a
developing solution 2 which is stirred by stirrer means 4 such as
pump or the like driven by a motor 3. The developing solution 2
thus stirred is moved through a pipe 5 into a substantially
trough-shaped developing tray 6. The portion of the developing
solution which has been brought to the developing tray 6 flows down
into the reservoir 1 through discharge holes 7 formed in the
developing tray 6. The reservoir 1 is divided into two compartments
by a partition wall 25, that is, compartment 28 just underlying the
developing tray 6 and compartment 29 having the stirrer means 4
disposed therein. The partition wall 25 is formed with cut-aways
26.sub.1 and 26.sub.2 for permitting the developing solution which
has flowed down from the developing tray 6 into the compartment 28
to circulate between the two compartments 28 and 29 of the
reservoir 1. According to the present invention, a concentration
detector 8 is disposed in the developing solution within the
reservoir 1. The concentrations detector 8 comprises a detection
circuit constituted by a source of radiation L and elements CdS1
and CdS2 sensitive to the source of radiation, as shown in FIG. 5.
In the flow passage of the developing solution which is provided by
the cut-away 26.sub.1 formed in the reservoir, there is disposed an
auxiliary tank 10 for containing concentrated liquid therein. As
shown in FIG. 6, the auxiliary tank 10 is formed with a discharge
port 9 for supplying a predetermined amount of concentrated liquid,
and at the inner and outer ends of the discharge port 9 there are
provided valves 12 and 13 mounted on a valve rod 11. The open inner
end of the discharge port 9 is normally closed by the valve 12
urged downwardly by a spring 18 mounted in the upper portion of the
valve rod 11.
Turning to FIG. 7, there is provided a rectifier circuit comprising
a power source transformer T.sub.1, diodes D.sub.1 to D.sub.4 and a
capacitor C.sub.1. The d.c. output of the rectifier circuit is
applied to a bridge circuit comprising resistors R.sub.1 and
R.sub.2 , a variable resistor R.sub.3 and elements CdS1 and CdS2
sensitive to the source of radiation L. When the concentration of
the developing solution 2 in the reservoir 1 is at a proper level,
equal quantities of radiation reach the two elements CdS1 and CdS2
sensitive to the source of radiation L. Thus the bridge circuit is
maintained in balanced state.
If the developing solution 2 decreases its concentration after a
great deal of development has been effected, the element CdS2
sensitive to the source of radiation also decreases its resistance
value to thereby destroy the balance of the bridge circuit, whose
output thus triggers an oscillation circuit comprising a transistor
Tr, an oscillating transformer T.sub.4 and a capacitor T.sub.4 and
a capacitor C.sub.2 . The output of the oscillation circuit is
applied to the gate of a bidirectional silicon controlled rectifier
element FLS, which is thereby turned on to actuate a plunger 14. In
this case, an input is intermittently applied to the plunger 14
through a microswitch MS in synchronism, for example, with action
of the operating mechanism of the image reproducing machine.
As shown in FIG. 1, the lower end of the plunger 14 is connected to
an arm 15 at one end thereof. The other end of the arm 15 is
connected to one end of an arm 17 by means of a rod 16 so that the
other end of the arm 17 controls the movement of the valve rod 11.
Thus, the movement of the plunger 14 is transmitted through the arm
15 and rod 16 to the arm 17 which in turn raises the valve rod 11
against the force of the spring 18 so that the valve 13 mounted on
the valve rod 11 closes the outer open end of the discharge port 9
for supplying a predetermined amount of concentrated liquid. Thus,
a predetermined amount of concentrated liquid fills the discharge
port 9. If the plunger 14 is released, the valve rod 11 is urged
downwardly by the spring 18 so that the valve 12 mounted on the
valve rod 11 closes the inner open end of the discharge port 9
while the outer open end of the discharge port is opened so as to
allow the predetermined amount of concentrated liquid filling the
discharge port 9 to fall into the reservoir 1. The described
sequence of operation is repeated with each actuation of the
plunger 14 so as to enable the concentrated liquid stored in the
auxiliary tank 10 to be supplied in predetermined amounts into the
reservoir 1. The concentrated liquid thus supplied into the
reservoir 1 is circulated by stirrer means 4 such as pump or the
like. When the concentration of the developing solution 2 thus
reaches the optimum level, it is detected by the concentration
detector 8 to thereby stop the actuation of the plunger 14.
According to the present invention, the concentration detector 8 is
disposed in the developing solution 2 within the reservoir 1 as
described above, and this arrangement eliminates the cumbersome
provision of pipe or like means and enhances the appearance of the
machine as compared with the prior art arrangement which included
the concentration detector disposed exteriorly of the reproducing
machine. Thus the arrangement of the present invention economizes
the space over the reservoir and is very advantageous in
designing.
In the illustrated form of the present invention, the concentration
detector 8 comprises, as shown in FIG. 5, a detection circuit
comprising a source of radiation L and elements CdS1 and CdS2
sensitive thereto, both contained in a casing 20 formed of
transparent material. The concentration detector 8 may be mounted
through an opening 21 formed in the cover plate 1.sub.1 of the
reservoir 1 in such a manner that the detector lies in the
developing solution 2 within the reservoir 1. Lead-out wires are
led out from the concentration detector elements L, CdS1 and CdS2
through a hole 23 formed in the lid member 22 of the casing 20. The
casing 20 and its lid member 22 may be constructed so as not to
allow the admission of the liquid thereinto by providing a tight
fit between the casing and lid member, so that developing solution
cannot enter the casing during the normal operation of the machine
and thereby the elements L, CdS1 and CdS2 of the concentration
detector can be readily protected from the liquid. Also, the lid
member 22 may be removed to change the source of radiation L within
the casing 20 and this means a great convenience in maintenance of
the device. Means 24 such as slit, filter or the like for
regulating the quantity of light may be provided in the light path
between the source of radiation L and the element CdS2. If the
means 24 is a slit, it will eliminate the problem of light
transmittivity which would result from the use of a filter, and the
provision of the slit itself can be simply achieved by ordinary
machining. Also, the use of the slit 24 leads to a further
advantage that the width thereof may be suitably selected so as to
select a proper resistance value for the radiation-sensitive
element CdS2 when the concentration of the developing solution is
proper. Further, a recess 27 for receiving therein the developing
solution to be measured may be formed in the bottom of the casing
20 and the casing 20 may be disposed in such a manner that the
recess 27 therein is in alignment with or closely proximate to the
cutaways 26, thereby allowing the developing solution 2 to flow
through the recess quickly enough to prevent the inner peripheral
surface of the recess 27 from being contaminated by the developing
solution. Thus, a highly accurate detection of the concentration of
the solution is accomplished.
* * * * *