SU1499308A1 - Apparatus for adjusting toner concentration in developing mixture - Google Patents

Abstract

The invention relates to electrography, can be used in electrophotographic apparatus with a dry method of preparation, and allows to increase the accuracy of maintaining a given concentration of toner in the developing mixture. The device contains a master oscillator, made in the form of a reference frequency with a fixed frequency, the detector - in the form of an amplitude one, in which the output voltage is proportional to the amplitude of the input voltage. Moreover, the inductive sensor is connected to the output of the master oscillator and to the detector input through interlocking coupling capacitors, the output of the toner concentration deviation signal amplifier is connected to the control input of the newly introduced generator, the pulse frequency of which is inversely proportional to the toner concentration deviation signal amplifier The generator is connected to the input of the amplifier, the load of which is the actuator adding toner to the developing mixture. 2 Il.

Description

The invention relates to electrophotography, and can be used in dry-scanning electrophotographic apparatus.

The aim of the invention is to improve the accuracy of maintaining a given concentration of toner in the developing mixture.

Fig. 1 is a schematic diagram of the device; FIG. 2 shows the amplitude-frequency characteristic of the inductive sensor and the adjustment characteristic of the device.

The device contains a master oscillator 1, a concentration control 2, blocking capacitors 3 and 4, an inductive toner concentration sensor 5, an amplitude detector 6, a concentration deviation signal amplifier 7 from a predetermined voltage, a voltage controlled oscillator 8, a toner adding actuator in the developing mixture,

The device works as follows.

The output signal of the master oscillator 1 through the blocking capacitor 3 is fed to the inductive sensor 5o. The setpoint adjuster 2 sets the required concentration value. Through the blocking capacitor 4 a signal, the amplitude of which is proportional to the toner concentration in the developing mixture, is supplied

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the amplitude detector 6, from the output of which the signal goes to the input of amplifier 7, the output voltage of which is proportional to the CEC toner concentration in the mixture and, therefore, inversely proportional to the deviation of the centering from the specified one. This voltage goes to the control input of the generator 8, which changes the frequency of the generated pulses depending on the applied voltage on the input, and the voltage on the input of the generator is proportional to the concentration of toner in the mixture, thus the frequency of the generated pulses depends on toner concentration in the developing mixture The output of the generator 8 is connected to the input of the amplifier 9, the load of which is the executive mechanism of adding toner to the developing mixture Each pulse of the generator 8 triggers the execution Yelnia mechanism and the mixture is added portionwise toner. The higher the frequency that is generated by 1 gx pulses, the more often the mechanism triggers and the faster the toner concentration rises.

If the inductive sensor is filled with a mixture with a maximum permissible toner concentration, t) the resonant frequency of the inductive sensor becomes f / j, a. (FIG. 2) The amplitude of the signal taken from the sensor is 0.7 Vm and after detection and amplification is sufficient to lock the generator 8, the output of which in this case will not have pulses. With a slight decrease in the toner concentration, the voltage decreases slightly and The generator 8 has been developed — the pulses of infra-low frequency and, thus, the necessary concentration level is maintained. With a sharp decrease in the toner concentration, the inductive sensor will be filled with the developing mixture with the minimum allowable toner concentration and resonance frequency will be equal to f (4UM. (Fig .2). The amplitude of the signal taken from the sensor decreases to 0.1 of the maximum level and the post-detection and gain is small, the frequency of the pulse generator 8 seen to rise rapidly and the concentration of a reducing

Vitsoyo

1 - Since the concentration of toner varies relatively slowly in a mixture,

then there will not be such sharp failures, because the toner consumption rate is proportional to the toner addition rate in the mixture and with a high sensitivity of the control circuit, a concentration deviation of 0.2% is sufficient for the generator 8 to enter the maximum dosing rate mode and the concentration required for normal operation, “High sensitivity has been restored and greater adjustment accuracy is ensured by the fact that during adjustment the operating point is on a steep slope of the resonance characteristic between the points. and C (FIG. 2)

The equivalent circuit of the setpoint adjuster 2 is a variable capacitor connected in parallel with the inductive sensor 5. Changing the capacitance of this capacitor, thereby changing the value of the resonant frequency of the inductive sensor

If, at the minimum concentration, the resonant frequency f / i is less than the frequency of the I for master oscillator by half the bandwidth, then setting the concentration adjuster to the desired position will increase the value of the resonant frequency to max and regulation will be performed relative to point B (Fig 2) wherein when the concentration increases, the amplitude of the signal taken from the sensor will increase, which will cause the generator 8 to turn off, and when the concentration decreases, the signal amplitude will decrease, which will turn on the generator 8, when the smaller the signal amplitude, the higher the frequency of the pulses generated by the generator 8,

Claims (1)

Invention Formula A device for controlling the concentration of toner in the developing mixture, which contains a master oscillator, an inductive toner concentration sensor, a detector, an output connected to the input of the first amplifier, a second amplifier, an output connected to the input of the actuator adding the toner to the mixture, that, in order to increase the accuracy of maintaining a given concentration of toner in the mixture, the unit of toner concentration has been introduced; rli S “  f / py fffff f for FIG. 2 //// 7/7