JPS6325668A - Toner concentration controller - Google Patents

Abstract

PURPOSE:To simply set the initializing of toner by providing the titled device with a changing means for changing the oscillation starting timing of a piezoelectric element depending upon the contact quantity of a developer and a means for feeding toner to a developing room from the start of the oscillation of the piezoelectric element up to the stop of oscillation. CONSTITUTION:The piezoelectric element 28 and an oscillation circuit 40 arranged in the developing room 14 constitute an oscillator 44 and the oscillation starting timing of the circuit 40 is set up by the position of a slider 42a of a variable resistor 42. An oscillation output from the oscillator 44 is compared with a reference voltage by a comparator 48 through an integrating circuit 46 and its difference output is inputted to a toner feeding roller driving circuit 52 and a display device 54 through an amplifier 50. At the setting time of initializing, the circuit 52 is turned off and developer 16 is fed into the developing room 14 up to 40-100% the height of the piezoelectric element. When the display device 54 is not lighted, i.e., the piezoelectric element 28 is not oscillated, the slider 42a is slided so as to be moved up to the oscillation starting position. Then the circuit 52 is turned on.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a toner concentration control device, and more particularly to a toner concentration control ff device that detects the toner concentration in a developing chamber using a piezoelectric element.

(Prior Art) In electronic copying machines and the like that use two-component developers, there is a device that uses a piezoelectric element to detect the toner concentration in the developing chamber.
For example, it is disclosed in Japanese Patent Application Laid-Open No. 158668/1983. In this conventional apparatus, a piezoelectric element is provided in the developing chamber, and at the time of initial setting, developer is introduced to a detection level at which the piezoelectric element starts and stops oscillating.

(Problems to be Solved by the Invention) In the above-described conventional apparatus, the work of initial setting the toner density is extremely complicated. In other words, under normal usage conditions, a decrease in toner concentration is detected by the oscillation of the piezoelectric element, but the level (contact area) of the piezoelectric element that starts oscillation is
Since the toner density was fixed at a certain level, it was necessary to input a developer with a known toner concentration according to the level at the time of initial setting. This developer is added by a skilled service person, but if too much is added, the piezoelectric element will not oscillate, so it is necessary to remove the developer until it reaches a predetermined level at which it starts oscillating. It is very complicated and time consuming, as it requires additional input when the toner density is exceeded.Therefore, the main purpose of the present invention is to provide a toner density control device that can easily initialize the toner density. That's true.

(Means for Solving the Problems) Simply put, the present invention includes a developer chamber in which developer is stored, a piezoelectric element that is provided in the developer chamber so that the developer comes into contact with it, and that constitutes an oscillator; A changing means for changing the timing at which oscillation of the piezoelectric element starts depending on the amount of developer contact; and a toner supply for supplying toner to the developer chamber when the piezoelectric element starts oscillating until the oscillation of the piezoelectric element stops. 1 is a toner density control device comprising means for controlling a toner concentration.

(Function) At the time of initial setting of toner concentration, first, a developer with a known toner concentration, that is, a developer with a known ratio of toner to carrier, is introduced into the developer chamber. If the amount of developer thrown in is within the range that can be detected by the piezoelectric element, the change means causes the piezoelectric element to start oscillating at the same time as the amount of developer thrown in, regardless of the amount of developer thrown in. Set.

When the oscillation start timing is initially set, when the piezoelectric element starts oscillating in subsequent use, the toner supply means supplies toner to the developer chamber until the oscillation stops. Therefore, the set amount of developer is maintained, and the toner concentration is maintained constant.

(Effects of the Invention) According to the present invention, at the time of initial setting of toner density,
As long as the amount of developer put in is within a predetermined range, the oscillation start timing of the piezoelectric element can be set regardless of the amount of developer. There is no need to add it, and it is used for the initial setting of toner density.
) No training required.

Therefore, anyone can initialize the toner density, and the initial setting work time can be significantly shortened.

Further, when the initial setting of the toner concentration is completed, the toner supply means supplies toner to the developer chamber by the amount reduced according to consumption, so that the toner concentration in the developer chamber is kept constant. Therefore, since an appropriate amount of toner can be supplied from the developer chamber to, for example, the photoreceptor, good development can be performed at any time.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Embodiment) FIG. 2 is an illustrative view of the main parts of an electronic copying machine to which the present invention can be applied. Although the present invention will be described below as being applied to an electronic copying machine, it is to be understood that the present invention can also be applied to other image forming apparatuses other than such electronic copying machines, such as printers and facsimile machines. I would like to point out this in advance.

The developing device 10 includes a developer chamber 14 arranged near the photoreceptor drum 12 . A two-component developer 16 consisting of carrier and toner is stored in the developer chamber 14 . The toner concentration of the developer 16 is, for example, 60 g of toner mixed with 1 kg of iron powder as a carrier.
% are selected. The toner concentration of the developer 16 is kept constant at 6%. That is, the amount of toner in the developer chamber 14 decreases due to toner development on the photoreceptor drum 12, but since the carrier is constant, the toner concentration decreases. Then, since toner is supplied by a toner supply cola, which will be described later, the toner concentration in the developer chamber 14, that is, the ratio of toner to carrier, is kept constant.

The toner replenished into the developer chamber 14 is first agitated with the accumulated developer 16 by the stirring blade 18 . Thereafter, the toner and carrier are stirred by a stirring screw 2° so that the toner and carrier are uniformly mixed. and,
A magnetic brush of the developer 16 is formed by the magnetic attraction force of the mag roller 22, and this magnetic brush is transferred together with the mag roller 22 rotating in the direction of the arrow (clockwise).

During the transfer, the height of the magnetic brush is adjusted by the blade 24, and then, at the position closest to the photoreceptor drum 12, only the toner is attracted to the photoreceptor drum 12 by the electrostatic force of the electrostatic latent image. The magnetic brush remaining without being attracted to the electrostatic latent image is further transferred to the upper part by the rotation of the mag roller 220, and finally scraped off by the scraper 26.

The magnetic brush, that is, the developer 16 scraped off by the scraper 26, is returned onto the stirring blade 18 again.
Developer 16 accumulated so that the toner concentration is uniform
mixed with.

A piezoelectric element 28 for detecting the upper surface of the developer 16 is provided on the right side wall of the stirring blade 18 . The piezoelectric element 28 is
The area in contact with the developer 16, i.e. the developer 1 that acts
The oscillation is started or stopped depending on the pressure of 6. That is, the toner concentration in the developer chamber 14 is determined by the piezoelectric element 28.
detected by. Since the carrier in the developer chamber 14 does not change even when the toner is consumed, the upper surface of the developer 16 lowers when the toner is consumed. In this case, the pressure acting on the piezoelectric element 28 becomes smaller, so the piezoelectric element 28
starts oscillating. The oscillation output of the piezoelectric element 2 is given to a toner supply roller drive circuit (described later), and when the toner supply roller 30 is driven, toner 1 is supplied from the toner hopper 32.
6a is supplied.

Therefore, the toner concentration in the developer chamber 14 is
It is controlled to be constant by controlling the upper surface (developer amount) of 6 to be kept constant.

Inside the toner hopper 32, there is a toner stirring blade 33 for stirring the toner 16a so that the supplied toner amount 6a does not solidify, that is, so that the toner supply roller 30 can smoothly supply the toner 16a to the developer chamber 14. provided.

A side passage 34 is provided on the right side of the toner amount/flange 32 for introducing the developer 16 having a known toner concentration at the time of initial setting of the toner concentration. In this device, when the toner concentration is set, that is, when the oscillation start timing (threshold) of the piezoelectric element 28 is set, the amount of developer 16 to be kept constant during use is also determined, and this determined development The amount of agent 16 is maintained to keep the toner concentration constant. When charging the developer 16 from the side channel 34, use the toner hopper 3.
As in the case of replenishing toner in No. 2, after lifting the knob 36 and opening the toner lid 38 upward, the side channel lid 39 is further opened.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The piezoelectric element 28 constitutes an oscillator 44 together with an oscillation circuit 40, and a variable resistor 42 is connected to the oscillation circuit 40.

Therefore, the oscillation start timing of this oscillation circuit 40 is set by sliding the slider 42a of the variable resistor 42. That is, the piezoelectric element 281 oscillation circuit 40 and the variable resistor B42 constitute an oscillator 44 that starts oscillating when the amount of developer 16 in the developer chamber 14 becomes less than the initial setting, that is, when the toner concentration decreases. .

The output of the oscillator 44 is provided to an integrating circuit 46 for integrating the oscillation output. The integration circuit 46 is an RC integrator composed of a resistance R and a capacitance C. Integrating circuit 46
The integral output is output only when the oscillation output is supplied from the oscillation circuit 40. The output of the oscillation circuit 40 integrated by the integrating circuit 46, that is, the charging voltage of the capacitor 1c, is provided to a comparator 48. This comparator 48 is -
A reference voltage is applied to one input terminal, and a voltage from the integrating circuit 46 is applied to the other input terminal. Therefore, when the output voltage of the integrating circuit 46 exceeds the reference voltage, the output terminal of the comparator 48 becomes high level.

The output of comparator 48 is provided to amplifier 50.

This amplifier 50 is, for example, a PNP whose emitter is grounded.
Consists of one type transistor. At this time, the base of the transistor becomes an input terminal and is connected to the output terminal of the comparator 48. The collector becomes the output terminal of the amplifier 50.

A toner supply drive circuit 52 and a display 54 are connected to the output terminal of the amplifier 50. Toner supply drive circuit 52
When an amplified output is given from the amplifier 50, that is, when the toner concentration in the developer chamber 14 decreases, the toner supply roller 30 is driven in order to keep the toner concentration constant. When the toner supply roller 30 is driven, the toner 16a is supplied from the toner hopper 32 into the developer chamber 14. The display 54 indicates that the toner supply drive circuit 52
This indicates that the toner 16a is being supplied from the toner hopper 32 when the toner supply roller 30 is being driven. Therefore, the display 54 indicates that the toner 1
It may be any device that informs the operator that 6a is being supplied, and may consist of one LE, one D, etc., for example.

FIG. 3 is a specific circuit diagram of the oscillator 44 shown in FIG. 1. In this example, the piezoelectric element 28 is configured as a three-terminal element, its common electrode is grounded, the other electrode is connected to the (-) terminal of the amplifier 56, and the other electrode is connected to the output of the amplifier 56 via a resistor 58. Connected to the terminal. Further, the output of the amplifier 56 is connected to the (-) terminal via a resistor 60. Therefore, a feedback loop is formed at the (-) terminal of the amplifier 56 by the piezoelectric element 28 and the resistors 58 and 60. The oscillation frequency of this oscillator 44 is determined by the inductance and capacitance C of the piezoelectric element 28 and the constants of the resistor 58 and 60.

The DC voltage Vcc is connected to the (+) terminal of the amplifier 56 through the resistor 6.
The partial pressure is given by 2 and 64.

The connection point between the resistor 58 and the piezoelectric element 28, that is, the piezoelectric element 2
One terminal of a variable resistor 42 is connected to the input terminal 8, and the other terminal of the variable resistor 42 is grounded via a resistor 66. Therefore, by changing the input resistance (input impedance) of the oscillator 44 with the variable resistor 42, the oscillation start timing, that is, the oscillation sensitivity, can be set.

In this way, the sensitivity of the oscillator 44, that is, the amount of developer 16 at which the piezoelectric element 28 starts oscillating, is controlled by the slider 42a.
can be set by adjusting.

FIG. 4 shows a graph of the rate of change in resistance of the variable resistor 42 with respect to the amount of developer 16 when the toner rate is initially set. In FIG. 4, the horizontal axis shows the height of the developer 16 in contact with the piezoelectric element 28, and the vertical axis shows the rate of change in resistance of the variable resistor 42. As is clear from FIG. 4, the rate of change in resistance of the variable resistor 42 is the same as that of the piezoelectric element 28 shown in FIG.
If it is 1.0 at a position of 40% from the lower end, it will be approximately four times as large at the 100% position, that is, when the upper surface of the developer 16 hits the upper end of the piezoelectric element 28. Therefore, developer 16
The rate of change in resistance changes linearly in a range where the amount is 40% to 100% of the area of the piezoelectric element 28, and if the oscillation start timing of the oscillator 44 is set within this range, the toner concentration can be detected accurately. I understand.

Next, what about the operation or operation of this embodiment, especially the toner? The operation at the time of initial setting of agricultural rate will be explained.

When initializing the toner density, first set the developer 16.
Turn on the switch (not shown) for initial settings. Then, the stirring blade 18, stirring screw 20, and mag roller 22 in the developer chamber 14 are driven, and the first
The toner supply drive circuit 52 shown in the figure is turned off. Then, in the initial 1 setting operation, even when the display 54 is lit, the toner supply drive circuit 52 is turned off, so the toner supply roller 30 is not driven.

After turning on a switch (not shown) for initial setting, open the toner M38 and the side channel cover 39 upwards and supply the developer 16 with a known toner concentration from the side channel 34, for example, the toner concentration is 6.
% developer 16 is put into the developer chamber 14. As shown in FIG. 5, the amount of developer 16 to be introduced is determined by
Any height may be used as long as it is within the range of 40 to 100% of the height.

After the developer 16 has been added, the toner lid 38 and the bypass lid 39 are closed, and the operation for initializing the toner concentration is started.

Initial setting is performed by sliding the slider 42a of the variable resistor 42. When the indicator 54 is not lit when the developer 16 is put into the developer chamber 14, that is, when the piezoelectric element 28 is not oscillating, the slider is set so that the resistance value of the variable resistor 42 increases. 42.Slide 3. Then, when the piezoelectric element 28 starts oscillating, that is, when the indicator 54 lights up, the slider 42a is returned slightly in the direction in which the oscillation is stopped. When the oscillation stops there, the slider 42a is moved in the direction in which the oscillation starts again. In this way, the position of the slider 42a is set at the critical point between the position where the piezoelectric element 28 starts oscillating and the position where the oscillation stops. The boundary point between the start of oscillation and the stop of oscillation of the piezoelectric element 28 is determined by confirming that the display 54 is blinking.

If the piezoelectric element 28 starts oscillating after the developer 16 with a known toner concentration has been put into the developer chamber 14, the value of the variable resistor 42 is set to a small value so that the oscillation stops. The slider 42a is moved in the direction. Then, when the piezoelectric element 28 stops oscillating, the slider 42a is slightly moved in the direction in which it starts oscillating again. In this way, the slider 42a is set at the point where the indicator 54 blinks.

When the position of the slider 42a is determined in this way,
This means that the initial setting of the toner density has been completed. That is, the height at which the piezoelectric element starts oscillating on the second day is set by the amount of developer 16 introduced from the side channel 34.

When the initial setting of the toner density is completed, a switch (not shown) that was turned on when performing the initial setting is turned off. Then, the toner supply drive circuit 52 which had been turned off returns to the active state, and when an amplified output is given from the amplifier 50 in subsequent use, the toner supply roller drive circuit drives the toner supply roller 30 accordingly. therefore,
At this time, toner 1 is transferred from the toner hopper 32 to the developer chamber 14.
6a is supplied until the piezoelectric element 28 stops oscillating.

When the toner 16a is replenished into the developer chamber 14 by driving the toner supply roller 30, that is, when the oscillator 44
When the piezoelectric element 28 is oscillating, the indicator 54 is always lit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is an illustrative structural diagram of the main parts of an electronic copying machine as an embodiment of the present invention. FIG. 3 is a specific circuit diagram of the oscillator shown in FIG. 1. FIG. 4 is a graph for explaining the operations of FIGS. 2 and 3. FIG. 5 is an illustrative diagram for explaining the operation of the piezoelectric element and developer shown in FIG. 2. In the figure, 14 is a developer chamber, 28 is a piezoelectric element, 30 is a toner supply roller, 32 is a toner hopper, 42 is a variable resistor, 44 is an oscillator, and 52 is a toner supply roller drive circuit. Patent Applicant Sanyo Electric Co., Ltd. Agent Patent Attorney Yama 1) Yoshihito (and 1 other person) No. 1 N Fig. 5 Fig. 2

Claims (1)

[Scope of Claims] 1. A developer chamber in which a developer is stored; a piezoelectric element that is provided in the developer chamber so that the developer comes into contact with it and constitutes an oscillator; and a piezoelectric element that depends on the amount of contact of the developer. toner concentration, comprising: a changing means for changing the timing at which the element starts oscillating; and a toner supplying means, when the piezoelectric element starts oscillating, supplying toner to the developer chamber until the oscillation of the piezoelectric element stops. Control device. 2. The toner concentration control device according to claim 1, wherein the changing means includes means for changing the sensitivity of the piezoelectric element. 3. The toner concentration control device according to claim 1 or 2, wherein the changing means includes variable resistance means connected to an input of the piezoelectric element. 4. The toner concentration control device according to claim 3, wherein the variable resistance means includes a variable resistor, and the changing means includes means for moving a slider of the variable resistor. 5. Claim 1, wherein the toner supply means includes a toner hopper that is provided on the developer chamber and stores toner, and a toner supply roller that supplies toner from the toner hopper to the developer chamber. The toner concentration control device according to any one of items 1 to 4. 6. Claims include an inlet provided in the developer chamber for injecting the developer in which toner and carrier are mixed in a predetermined ratio when setting the oscillation start timing of the piezoelectric element. The toner density control device according to any one of items 1 to 5.