JPS58105261A - Developer density controlling system - Google Patents

Abstract

PURPOSE:To execute satisfactory density control by detection of high accuracy, by counting the frequency from a density detector at constant time intervals, and replenishing a toner only when the number of times which has gone out of the first reference value exceeds the second reference value. CONSTITUTION:A detecting part 18 is constituted by winding a coil 18b around a bobbin 18a which a developer passes through, and a density detector 20 is constituted by connecting the coil 18b to an oscillating circuit 19. A frequency signal (f) outputted from this detector 20 is inputted to a microcomputer (MIC ON) 21, and is counted as a pulse by an internal event counter. In the microcomputer 21, the number of times by which this event counter has become a prescribed value or below in a prescribed time is counted by the second counter. When this number of times of counting exceeds a set value and the lower limit density is detected, a toner replenishing signal is generated, a replenishing clutch is turned on, and a toner is replenished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developer concentration control method in a developing device.

In a developing device such as a copying machine, if the density of the developer becomes low, clear copies cannot be obtained; if the density of the developer becomes too high, background stains are likely to occur. Therefore, it is necessary to always keep the developer at an appropriate concentration by replenishing toner according to the amount used.

Conventionally, developer concentration control in such a developing device has been carried out by transmitting a signal at a frequency proportional to the amount of developer obtained from a density detector 1 to an integrating amplifier 2, a detector 3, and a direct current, as shown in diagram ts1. This is done by converting to a voltage level through an analog circuit such as an amplifier 4, and comparing this with a set voltage in a comparator 5 to control the amount of toner supplied.

However, in the above-mentioned conventional method, accurate density control cannot be performed due to the influence of drift occurring in the analog circuit, and there is a problem in that the copy becomes blurry or thin depending on the temperature.

Moreover, since an analog bypass is used and, as a result, a drift) correction circuit needs to be added, the U+
There was also the problem that the control circuit was complicated and expensive.The present invention uses a microcomputer, which is recently available with high performance and low cost, in place of the conventional analog/4G circuit. The purpose of this invention is to provide a highly accurate developer concentration control force formula.

In order to achieve this objective, the present invention uses a microcomputer to count one wave number obtained from a concentration detector as a pulse number several times at regular time intervals.
#11 The number of times the difference exceeds the reference value is determined, and toner is replenished only when this number of times exceeds the second reference value.

Embodiments of the present invention will be described below with reference to the drawings.
3 is a photosensitive drum.

The developer consists of a magnetic carrier and toner. When a replenishment clutch (not shown) is turned on, the toner replenishing member 14 rotates, and the toner is replenished from the toner container 11 to the developer container 12. The replenished toner is stirred with the magnetic carrier by the stirrer 15 and conveyed to the photosensitive drum 13 by the developing sleeve 16. As a result, one image on the drum 13 is visualized. Further, the amount of the developer supplied toward the developing sleeve 16 by the stirrer 15 is regulated by the doctor 17, and the excess developer is circulated so as to pass through the detection section 18.

As shown in Figure #13, this detection unit 18 is made up of a coil 18b wound around a bobbin 185 through which the developer passes.
The coil 18b is connected to an oscillation circuit 19 to constitute a concentration detector 20. Further, the pigeon wave number signal f output from the concentration detector 20 is input to a self-microphone computer (hereinafter referred to as a microcomputer) 21.

Various types of microcontrollers can be used as this microcomputer 21, but
In this embodiment, an Intel 8048 chip is used. The reason for this is that this chip is equipped with an event counter that can count external events without placing any extra burden on the ruminal setter. That is, at this event counter, the output frequency f from the s Liao detector 20
This means that it is pulsed and counted. In addition, since this event counter is configured with 8 bits and can count 256/< pulses, in this embodiment, the standard wave number fstl output from the concentration detector 2o at the appropriate developer concentration is
Adjust to oOKHg and set the measurement time to 2ms. As a result, when the developer concentration is appropriate, the event counter will be 2.
00 pulses are counted, and in a normal state, the output same wave #f necessary for control can be outputted without overflowing.

The microcomputer 21 includes a console 22, a display 23, and other necessary input/output devices. DC load details 24 is l
When the developer concentration is controlled, a9y4- of the toner replenishing member 14 is turned on and off by the output of the microcomputer 21.
F controlled.

The developer control pupil of this embodiment is configured as described above,
By processing the output frequency f of the concentration detector 2o by the microcomputer 21, the replenishment clutch is controlled to turn on and off, and the developer in the developer container 12 is controlled to have an appropriate concentration.

That is, since there is a proportional relationship between the developer concentration in the developer container 12 and the output frequency f from the concentration detector 20, the output frequency f is used as the pulse number by the event counter of the microcomputer 21, as will be explained in detail later. Count.

At this time, if the developing device stops operating and the developer is not passing through the detection unit 18, the inductance of the Lee coil, which has low magnetic permeability, also decreases, so the output frequency f will decrease as shown in FIG. It will be expensive (at TA time). When the circulation of the developer is started, the inductance increases and the output frequency f falls to the standard wave number fs (78 o'clock). Further, as the toner is used, the developer concentration and hence the output wave number f gradually decreases, and eventually reach the lower limit wave number fXJ. My Fun 2
1 is below Ig! A toner replenishment signal f is generated by detecting the pigeon wave number f-, and the replenishment clutch is turned on.

Then, toner is replenished from the toner container 11 to the developer container 12 and from the toner container 11 to the developer container 12, and as the developer concentration increases, the output frequency f also increases. However, in reality, it takes 'Cd time for the toner to circulate within the developer container 12 and reach the detection unit 18 after being replenished, resulting in a response delay. Therefore, if replenishment of one toner is continued until the output frequency f reaches the standard station wave number fs, the toner replenishment will be excessive, the developer concentration will rise too much, and the aforementioned background stain will occur. Also,
The fluidity of the developer deteriorates, and the developer may pass through the bobbin 18G, become clogged, and become undetectable.

Therefore, in this embodiment, in order to prevent such excessive toner replenishment, the replenishment clutch is turned off early, that is, at an intermediate station wave number fM lower than the standard wave number fs, taking into account the response delay time τdt. The intermediate station wave number fM at this time can be determined from the time d and the rate of increase of 1 of the output frequency f during toner replenishment mechanically.

In this way, if the replenishment clutch is turned on when the output frequency f falls to the lower limit wave number fL and turned off when it rises to the intermediate frequency fM, the output frequency f is always set to the standard station wave number fs.
It is possible to control the developer to an appropriate concentration.

Next, the developer concentration control outlined above will be specifically explained with reference to the free charge shown in Figure 5 and the time chart shown in Figure FS6.

In the case of this embodiment, as mentioned above, the measurement time of the output frequency f is 2sz, and this is set to lil by the soft timer.
to be accomplished. In addition, the standard sonic wave number f island at an appropriate concentration is 100 K.
As mentioned above, the count value of the event counter at this time is 200 pulses, but in addition, f) -9
Is KH Rin, count value 190 pulses, fM-99K
Hg, count 198 pulses.

Further, counter A in FIG. 5 is used to count the number of times the event counter becomes 190 or less at 2sz.

The counter P counts every time the 2ms timer times up, and is used to determine whether or not to turn on the replenishment clutch.

Counter B operates to count every time the event counter exceeds 198, and is used to judge whether or not to turn off the replenishment clutch.

The force counter Q is a counter that keeps the operating time of the replenishment clutch constant, and is normally set when the clutch is turned off.

This counter counts every time the counter P reaches 10, that is, the number of times the 2 sacrifice S timer times up.
It is used to determine the toner end when the replenishment clutch is not turned off even after 10 seconds.

Further, the over 70-flag is set when the number of pulses manually input to the event counter becomes 256 pulses or more within #warm time 2ss, and when the counted value changes from 255 to O&:.

First, the normal toner replenishment operation will be explained with reference to the diagram in FIG.

The processing of the microcomputer 21 starts from the main routine (not shown).
When proceeding to the check routine shown in the figure, program steps 8T1.8T2.8T3, ST4, and s'r5 are passed with No, respectively, 7 lag P is set at 8T6, and 8T7
After starting the event counter with , in order to measure the time of 2sz, the 2 inertia $ tie provided in the microcomputer 210 RAM at 8Tg! Add "1" to the memory section for

After that, it returns to the main routine once, but by cycling through the route that immediately returns to the check routine, -S
In the first period, time is measured by adding 1 to the memory section for 2 seconds and 1 timer. As a result, when the 21KI timer times up, 8T4 is passed by YB6 and 8T9
Then, the counter P configured using the hole ^M as described above is 1.
Increment.

After that, the above-mentioned 2ml timer is reset with 8TlO, the replenishment clutch is OFF, so 8T11 is passed with NO, and the developer concentration is appropriate, so 8T12 is also passed with No, and the event counter is set with 8T14 with s'r13. 7
Reset the lag r and return to the main routine. At this time, the main routine processes emergency interrupts and the like, then returns to the check routine and performs the 2ss time measurement process described above. In this way, every 2 inert3, 5T1
In the process of checking the event counter value in step 2, if the developer concentration decreases due to the use of toner and the 1 output frequency f drops close to the lower limit - wave number f There are cases where the value becomes 190 or less. Count this in counter A with 8T15,
"Counter PJ -1°, that is, 8T3 every 10 measurements.
After passing through 58T16 and 8T17, the contents of counter A become 8.
In other words, the number of times the event counter value becomes 190 or less is 8.
Check the number of times it is greater than or equal to the number of times. As a result, counter A
If the value of does not reach 8, counter A is set to 8T18, and 5T
The counter P is reset at step 19, and the process returns to the main routine via step 5T13.14. However, as such processing continues, the content of counter A increases as the developer concentration decreases, and eventually at %8T17, "counter A" ≧8.
Then ~ To measure the toner replenishment time, 8T2
At 0, the counter Q is incremented by 1, and at 8T21, the replenishment clutch is turned on.

In this example, in this way, the concentration measurement every 2 mB is performed once.
It is configured such that the lower limit concentration is detected when the number of times of emptying 21 of 190 pulses or less is 8 or more times. Therefore, the influence of minute fluctuations in the output frequency f due to non-uniform flow of the developer is canceled, making it possible to detect the developer concentration with high accuracy and stability.

After that, the process returns to the main routine via 8T18, 19, 13, and 14, but at this time it immediately returns to the check routine again. At the same time, every 2 mB time-up, the signal passes through 8T11 at yga, passes through 8T22.23, and detects the Nakanoseki pigeon wave number fM.

That is, the number of times the event counter becomes 198 or more is counted using counter B, and every 2filBXIQ 8
From T3, through 8T16, and at 8T24, "Counter B" ≧8 is checked. As a result, when the output frequency f reaches the Nakaseki Akebono wave number fM, &T24 is passed by YB2,
By resetting the replenishment clutch at 8T25 and resetting the counter Q at 0FFS8T26, developer concentration control is ended for the time being, and the program returns to the main routine via 8T1B, 19, and 13.14.

However, if the output frequency f does not reach the Nakaseki pulse number fM, as shown in the time chart of Fig. 6(b), monitor the time by branching from 8T24 to 8T20, and use the counter QJ-500. That is, about 2ms x 10
If 8T24 cannot be passed by YBS even after X500-1ag, it is determined that there is no toner in the toner container 11 width, and the flow moves from 8T2 to 8T27, and the replenishment clutch is turned to O.
At the same time, the toner end display is turned ON, the copy prohibition flag is set, the process returns to the main routine, and subsequent copying is prohibited.

On the other hand, if the developer stops flowing in the bobbin 18a of the detection unit 18 for some reason, the output frequency f of the concentration detector 20 increases, and the number of pulses input to the event counter exceeds 256 within 2 seconds. . As previously mentioned,
If the value of this event counter exceeds 255, the overflow flag is set, so the process changes STl to YE.
Passed at 8, toner clogging display turned on after 8730-32
.

Copy prohibition flag set, service machine call display ON
In this manner, according to the present embodiment, the developer concentration can be detected with high precision using the microcomputer 21, and as a result, the developer concentration can be stabilized without overpressure. In addition, the toner end and toner viscosity can be detected extremely economically without providing a separate detector, detection circuit, etc.

As described above, according to the present invention, the frequency output from the developer concentration detector is detected by counting the number of pulses, and the developer concentration is controlled. Control takes place. In addition, minute fluctuations in frequency due to variations in wrinkles when the developer passes through the detection section are averaged by measuring the number of pulses over a predetermined period of time. This is because detection is performed when the difference is exceeded a certain number of times, so that highly accurate detection is performed, and as a result, the developer concentration is well controlled.

[Brief explanation of the drawing]

#! Figure 1 is a block diagram for explaining the conventional method, and Figure 2 is a block diagram for explaining the conventional method.
The figure is a configuration diagram of a developing device according to an embodiment of the present invention, FIG. 3 is a control circuit diagram thereof, FIG. 14 is a time chart explaining its control operation, and FIG. 5 (α) # (b) is its control circuit diagram. 74-Chard explaining details of operation, Figure 6 No. Go II
A time chart showing the operation of each element based on the s-diagram.
(a) is a time chart during a normal toner replenishment operation, and (b) is a time chart when the toner runs out. l... Concentration detector, 2... Integrating amplifier, 3... Detector, 4... DC intensifier,
5... Comparator, 11... Fner container,
12... Developer container, 13... Photosensitive drum, 14... Toner supply member, 15...
... Stirrer, 16... Development sleeve, 17...
...Doctor, 18...Detection section, tea.
...Bobbin, 18b...-Coil, 19.
...Oscillation circuit, 20...Pensability detector, 2
1...-Y icon, 22...console, 23...display, 24...D
C loading group. Figure 7 Figure 2 Figure 3 Figure 2 Figure 4

Claims (1)

[Claims] In this method, a developer is applied to a coil, and changes in the inductance of the coil due to changes in the magnetic permeability of the developer are detected as changes in frequency, thereby detecting and controlling the concentration of the developer.
Count the number of pulses for a given time as the number of pulses
51 force counting means and counting the number of operations #1
2 counting means and a third counting means for counting the @elements each time the count value of the first counting means deviates from the first reference value, and the count value of the $2 counting means reaches the #12 reference value. means for checking the count value of the IJ43 counting means every time, and generating a toner replenishment overtone when the count value exceeds the $3 standard, and replenishing toner to the developing device based on the toner replenishment signal, A developer concentration control force type characterized in that the concentration of is controlled to a predetermined value.