JPS645299B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for setting a toner density control device in a copying machine or the like.

Conventionally, there are two methods for setting the toner density control device in a copying machine: one is to insert a standard developer into the developing section of the copying machine, and the other is to set the toner density control device using a dummy measuring object, such as a solid carrier or a dummy coil. There is a method for setting the toner density control device.
However, in the former case, a standard developer is always required, making it difficult to manage the standard developer in the inspection process. Furthermore, in the manufacturing inspection process, standard developer is taken in and out of the developing section, which takes time and increases costs. Furthermore, a service person who sets the toner concentration control device must be trained on how to set the toner concentration control device, and in some cases, the service person must always carry a standard developer with him or her. On the other hand, in the latter case, variations in developer and equipment cannot be suppressed, and the control range is widened, resulting in large fluctuations in image quality. Furthermore, when a service person replaces the developer at a user's location, he or she must always set a toner density control device, so the service person must always have a dummy measurement object on hand.

The present invention solves the above-mentioned problems, and provides a toner density control device that can easily set the toner density control device according to the developer used without using a dummy measurement object during the manufacturing inspection process or during service personnel maintenance. The purpose is to provide a method.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of a toner density control device to which the present invention is applied. A detector 1 detects the toner concentration of a two-component developer in a developing section of a dry electrophotographic apparatus. Although this detector 1 detects the toner concentration as a frequency, it may also be a detector that detects the color tone of the developer. The output signal of the detector 1 is converted into a voltage according to the toner concentration by a voltage converter 2, amplified by an amplifier 3, and compared with a reference voltage of a reference power source 5 by a comparator 4. Normally, the switch 6 is switched to the toner supply section 7 side,
The ground line of the toner replenishing section 7 is grounded by the switch 6, so that the toner replenishing section 7 is in an operative state, and the ground line of the reference voltage control signal generator 8 is opened, so that it is in an inoperative state. Therefore, the output signal of the comparator 4 is amplified by the amplifier 9 and applied to the toner replenishing section 7, and the toner replenishing section 7 replenishes the developer in the developing section with toner, thereby controlling the toner density to be constant. This is called toner density control mode. When a service person sets up this device at the user's location, such as when replacing developer, first insert the developer to be actually used into the developing section, turn switch 6, and set toner replenishing section 7 in the inactive state. The voltage control signal generator 8 is put into operation. Therefore, the reference voltage control signal generator 8 receives the output signal of the comparator 4, varies the reference power source 5, and adjusts the reference voltage so that the output voltage of the comparator 4 becomes zero. This is called measurement mode. After that, when the switch 6 is returned to its original state, the reference voltage is fixed as it is, and the toner concentration control operation is performed again. In this example, the switch 6 applies a DC voltage (ground voltage) signal to the toner replenishing section 7 and the reference voltage control signal generating section 8 to control the reference voltage. DC voltage (ground voltage)
The signals may be of any type, for example pulses with phase synchronization. Also, the reference voltage was set so that the output voltage of comparator 4 would be zero, but comparator 4
By adjusting the reference voltage control signal generator 8 so that the signal from the reference voltage control signal generator 8 stops (turns off) when the output voltage reaches the desired voltage, the toner concentration of the developer used can be adjusted. You can set any toner density from . In the manufacturing inspection process, it is determined where to set the threshold level for toner replenishment by adjusting for variations in the parts after comparator 4, then the developer is inserted into the developing section and the service person presses switch 6. You can easily and accurately set the settings. Even when the developer is replaced, the service person presses the switch 6 and the settings are made in accordance with the new developer, so anyone can easily make the settings and no unnecessary effort is required.
In this example, the signal from the detector 1 is converted into a voltage and processed, but it is clear that the signal detected by the detector 1 as a frequency of the toner concentration can also be processed in the same way without being converted into a voltage.

FIG. 2 shows another example of a toner density control device to which the present invention is applied. In this example, a coil 10 is wound around a developer flow path in a developing section of a copying machine, and a detector 11 using this coil 10 outputs an output by changing the inductance of the coil 10 according to the toner concentration of the developer. Frequency r changes. The reference device 12 outputs the reference frequency o, and the detector 11
The outputs of the reference device 12 and the reference device 12 are mixed in a mixing circuit 13, and the difference frequency (ro) component is extracted.
The output of this mixing circuit 13 is the frequency/voltage converter 1
4 performs frequency/voltage conversion and is input to the amplifier 3. DC power supply 15, resistor 16 and variable resistor 1
Reference numeral 7 constitutes a reference power supply having the same function as the reference power supply 5, and the voltage of the DC power supply 15 is divided by a resistor 16 and a variable resistor 17 and applied to the comparator 4 as a reference voltage. The reference voltage control signal generator 8 is generally made of a commercially available servo motor, and a variable resistor 1 is attached to the shaft of the servo motor 8.
7 is installed and the servo motor 8 is the comparator 4.
variable resistor 17 by inputting the output signal of
to vary the reference voltage. Generally, a servo motor rotates, stops, changes direction of rotation, or changes number of rotations depending on an input signal.
In this example, the reference voltage control signal generator 8 is configured with a servo motor by utilizing the characteristics of this servo motor.The servo motor 8 is rotated by the output signal of the comparator 4 and provides a driving force ( A reference voltage control signal) is applied to drive the variable resistor 17.
When the servo motor 8 rotates, the variable resistor 17 also rotates in the same direction, and when the servo motor 8 stops, the variable resistor 17 also stops. When the servo motor 8 rotates and the variable resistor 17 rotates, the resistance value of the variable resistor 17 changes and the reference voltage changes. Servo motor 8
stops and variable resistor 17 stops, variable resistor 1
The resistance value of 7 is fixed and the reference voltage is fixed.
In this way, the servo motor 8 applies the driving force according to the input signal from the comparator 4 as a reference voltage control signal to the variable resistor 17 to change the reference voltage, and constitutes a reference voltage control signal generator. There is.
First, we confirmed that the variations in the parts after amplifier 9 were very small, and found that if the output voltage of comparator 4 was set to zero, a stable and good copy image could be obtained. In order to do this, the input side of the servo motor 8 was disconnected and OV was input to the servo motor 8 using a separate power supply, and the servo motor 8 was configured to do so. At this time, it was confirmed that the sliding terminal of the variable resistor 17 attached to the shaft of the servo motor 8 was located approximately at the center, which corresponds to the range of variation in the signal voltage, and the circuit was based on this. After that, to set the toner density control device in measurement mode, I put developer into the developing section and pressed switch 6.
The servo motor 8 worked for about 10 seconds, and the output voltage of the comparator 4 became zero.

Furthermore, in the apparatus shown in FIG. 2, a toner replenishment signal from before the toner replenishment section 7 (from the comparator 4) is input to the servo motor 8, and the servo motor 8 stops when the toner replenishment signal changes from a low level to a high level. I set it to do so. In this case, only the servo motor 8 needs to be adjusted, so it is possible to set the servo motor 8 to turn off when the input is at a high level, but if the toner replenishment signal is at a high level when the switch 6 is turned on, the servo motor 8 A circuit (phase comparator circuit) for reversing the toner is incorporated in the servo motor 8, and the servo motor 8 is set so that when the switch 6 is turned on again, the servo motor 8 stops when the toner replenishment signal changes from a low level to a high level. By doing this, in the manufacturing inspection process, it was possible to reliably set the threshold level for toner replenishment using the developer used by simply adjusting the servo motor 8. This allows the service person to easily change the control level of toner density, and it is possible to stably obtain a copy image quality that suits the user.

Note that in the above embodiments, it is possible to shift the set level to a certain value and set it, and it goes without saying that the reference voltage can be controlled using means other than the servo motor.

As described above, according to the present invention, in a toner concentration control device that controls toner concentration by detecting the toner concentration of a developer and comparing it with a reference signal, and controlling toner replenishment according to the comparison result, A toner density control mode that controls density;
The mode switching means switches the measurement mode for setting the toner concentration control device, disables toner concentration control in the measurement mode, and detects the toner concentration using the same developer used in the toner concentration control mode. Since the reference signal is set using the output signal of the reference signal, the setting can be easily performed, and a dummy measurement object or standard developer is not always required.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing examples of toner density control devices to which the present invention is applied. 4...Comparator, 5...Reference power supply, 6...Switch, 8...Reference voltage control signal generator.

Claims (1)

[Claims] 1 In a toner concentration control device that controls toner concentration by detecting the toner concentration of a developer and comparing it with a reference signal and controlling toner replenishment according to the comparison result, toner concentration control that controls toner concentration mode and the measurement mode switching means for setting the toner concentration control device, toner concentration control is disabled in the measurement mode, and the toner concentration is detected using the same developer used in the toner concentration control mode. A method for setting a toner density control device, characterized in that the reference signal is set using the output signal thereof.