JPS62220980A - Toner concentration controller - Google Patents

Abstract

PURPOSE:To easily set toner concentration initially by providing a varying means for varying the oscillation start period of a piezoelectric element depending upon the quantity of contacting of a developer. CONSTITUTION:The piezoelectric element 28, an oscillation circuit 40, and a variable resistor 42 constitute an oscillator 44 which begins to oscillate when the developer in a developer chamber becomes less than at the time of initial setting, i.e. when the toner concentration decreases. Here, the input resistance of the oscillator 44 is varied by the variable resistor 42 to set the start period of oscillation, i.e. oscillation sensitivity. Consequently, a developer whose toner concentration is know severely need not be put in at the time of the initial setting and there is no need for skillfulness for the initial setting of the toner concentration. Consequently, even a beginner can set the toner concentration initially and the operation time of the initial setting is shortened greatly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a toner density control device, and more particularly to a toner density control device that detects toner density within 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. If the amount exceeds the required amount, additional input must be made, which is very complicated and time-consuming.

Therefore, a main object of the present invention is to provide a toner concentration control device that can easily initialize toner concentration.

(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; and a toner concentration control device including a changing means for changing the oscillation start timing of the piezoelectric element depending on the contact amount of the developer.

(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.

Once the oscillation start timing is set, during use, the amount of developer thus set is maintained, and the toner concentration of the developer 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 charge the toner, and no skill is required to initialize the toner density. Therefore, anyone can initialize the toner density, and the initial setting work time can be significantly shortened.

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 ta degree decreases. Then, since toner is supplied by a toner supply roller, 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 . Furthermore, after that, the toner and carrier are stirred by the stirring screw 20 so that the toner and the 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 upward by the rotation of the mag roller 22, and is 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 and mixed with the accumulated developer 16 so that the toner concentration is uniform.

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 28 is input to a microcomputer, which will be described later.The microcomputer outputs a drive signal for the toner supply roller 30, and the toner 16a is supplied from the toner hopper 32.

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.

A toner stirring blade 33 is provided in the toner hopper 32 to stir the toner 16a so that the supplied toner 16a does not solidify, that is, so that the toner supply roller 30 can smoothly supply the toner 16a to the developer chamber 14. It will be done.

A side passage 34 is provided on the right side of the toner hopper 32 for introducing the developer 16 having a known toner concentration when initially setting 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 Agent 1
By maintaining the amount of 6, the toner density is kept constant. Side road 3
When introducing the developer 16 from the toner hopper 32
Similarly to when replenishing toner, after lifting the knob 36 and opening the toner lid 38 upward, the side passage M39 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 42 operate 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. Configure.

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 ff1C. The integration circuit 46 outputs an integral output only when the oscillation output is supplied from the oscillation circuit 40. The output of the oscillation circuit 40 integrated by the integration circuit 46 is applied to the input port of the microcomputer 50 via the buffer 48.

The microcomputer 50 controls not only the toner concentration in the developer chamber 14 but also the operation of the entire electronic copying machine. Although not shown in detail, the microcomputer 50 includes a CPU, a ROM connected to the CPU for storing control programs, and a ROM for temporarily storing data during control by the CPU. R having areas for various flags necessary for control, a timer area, and a table for driving the motor that slides the slider 42a.
AM is included.

Another input port of the microcomputer 50 includes a switch 52 that is operated when initializing the toner concentration.
The terminal of one of the contacts is connected. The other contact of switch 52 is grounded. This switch 52 is an automatic return switch that is turned on only when it is pressed.

A motor drive circuit 54 for driving a motor 56 for moving the slider 42a of the variable resistor 42 is connected to an output port of the microcomputer 50. The motor drive circuit 54 rotates the motor 56 for a necessary time or by a necessary angle. For this purpose, 1. The motor 56 may be any motor whose rotation amount or rotation angle can be controlled, such as a geared motor connected to a transmission, a stepping motor, or a servo motor. In accordance with the rotation of the motor 56, the slider 42a of the variable resistor 42 is moved.

A display 58 is connected to another output port of the microcomputer 50 to inform the operator that the initial setting of the toner concentration has been completed. Furthermore, when the oscillation output from the oscillator 44 is input to the micro combinator 50, that is, when the toner concentration in the developer chamber 14 decreases, the other output port of the microcomputer 50 is used to keep the toner concentration constant. toner supply roller 30
A toner supply drive circuit 60 for driving the toner hopper 32 to supply the toner 16a from the toner hopper 32 is connected thereto.

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, whose common electrode is grounded, the other electrode is connected to the (-) terminal of the amplifier 62, and the other electrode is connected to the output terminal of the amplifier 62 via a resistor 64. connected to. In addition, the amplifier 62
The output of is connected to the (-) terminal via a resistor 66. Therefore, the piezoelectric element 28 is connected to the (-) terminal of the amplifier 62.
A feedback loop is formed by resistor 64 and resistor 66. 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 resistors 64 and 66.

The DC voltage Vcc is connected to the (+) terminal of the amplifier 62 through the resistor 6.
The partial pressure is given by 8 and 70.

The connection point between the resistor 64 and the piezoelectric element 28, that is, the piezoelectric element 2
One terminal of a variable resistor 42 is connected to the input of the variable resistor 8, and the other terminal of the variable resistor 42 is grounded via a resistor 72. Therefore, with the variable resistor 42, the oscillator 44
By changing the input resistance (human impedance) of the oscillation, 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 concentration 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, if the resistance change rate of the variable resistor 42 is 1.0 at a position 40% from the bottom end of the piezoelectric element 28 shown in FIG. When the upper surface of the piezoelectric element 28 coincides with the upper end of the piezoelectric element 28, it becomes approximately four times as large. Therefore, the resistance change rate changes linearly when the amount of developer 16 is in the range of 40% to 100% of the area of piezoelectric element 28, and if the oscillation start timing of oscillator 44 is set within this range, it will be accurate. It can be seen that the toner concentration can be detected.

Next, referring to FIG. 1 and based on the flowchart shown in FIG. 5, the operation of this embodiment, particularly the operation at the time of initial setting of toner density, will be described.

When initializing the toner density, first, with the power of the copying machine turned off, switch 52 shown in FIG. 1 is turned on to turn on the power of the copying machine. Then, the microcomputer 50 is placed in the toner density initial setting mode.

Thereafter, the toner M38 and the side passage i39 are opened upward, and the developer 16 having a known toner concentration, for example, the developer 16 having a toner concentration of 6%, is introduced into the developer chamber 14 from the side passage 34. The amount of developer 16 to be introduced may be arbitrary as long as it is within the range of 40 to 100% of the height of the piezoelectric element 28, as shown in FIG. After adding the developer 16, close the toner lid 3.
8 and the side channel cover 39 and turn on the switch 52 again. Then, the microcomputer 50 enters the operation of initializing the toner density.

In the first step Sll of initial setting, switch 5
2 is determined to be on. If it is confirmed that the switch 52 is turned on, in step 313 the process proceeds to the next step S13.
The microcomputer 50 determines whether this routine is executed for the first time or the second time by looking at the counter of the area allocated to the RAM. If it is determined in step S13 that it is the first time, the process advances to the next step S15.

In step S15, the oscillator 44, that is, the piezoelectric element 2
8 oscillates and the oscillation output is input to the microcomputer 50. If the piezoelectric element 28 is not oscillating, in the next step S17, a drive signal is applied from the output port of the microcomputer 50 to the motor drive circuit 54, and the motor 56 rotates forward for a certain period of time. When the motor 56 rotates forward for a certain period of time, the slider 42a of the variable resistor 42 is moved by a certain amount or a certain angle accordingly. Thereafter, the process returns to step S15. Then, in step S15, it is determined again whether the piezoelectric element 28 has started oscillation. If oscillation is not started, the process proceeds to step S17 again, the motor 56 is rotated forward for a certain period of time, and steps S15 and S1 are continued until oscillation is started.
Repeat step 7.

If it is determined in the previous step S15 that the piezoelectric element 28 has started oscillation, the process advances to step 319. In step 319, when oscillation is confirmed by inputting the oscillation output of the oscillator 44 to the microcomputer 50 in step SL5, the motor drive circuit 54 is driven to reverse the motor 56 for a certain period of time, as in step S17. A signal is given. By rotating the motor 56 in reverse for a certain period of time, the slider 42a of the variable resistor 42 is slid by a certain amount or a certain angle. This sliding movement of the slider 42a moves in the direction of stopping the oscillation of the piezoelectric element 28. The process then returns to step S13.

Next, in step S13, it is determined that this routine is not the first time, and the process advances to the next step S21.

In step S21, it is also determined whether the piezoelectric element 28 is oscillating. That is, on the way to step 321, step S19 is always passed, and here the slider 42 is moved in the direction of stopping the oscillation of the piezoelectric element 28.
a has been moved. Therefore, this step 319
If the amount moved in step S21 is sufficient to stop the piezoelectric element 28, the piezoelectric element 28 is moved in step S21.
No oscillation was confirmed. Conversely, if the piezoelectric element 28 continues to oscillate even though the slider 42a is slid in step S19, the slider 42a is further slid in the direction to stop the oscillation of the piezoelectric element 28. In order to do so, the process returns to step S19.

If oscillation of the piezoelectric element 28 is not confirmed in step S21, the process advances to the next step S23. In step S23, a fixed time is measured by a timer area allocated in the RAM, and after the fixed time has elapsed, the process proceeds to step 325.

Next, in step S25, it is checked again whether the piezoelectric element 28 has started oscillation. That is, even if it is determined in the previous step 321 that the piezoelectric element 28 is not oscillating and the process proceeds to step S25, after a certain period of time has elapsed, the top surface of the developer 16 will be averaged out by collapsing the peak, etc. The piezoelectric element 28 may start oscillating. The oscillation of the piezoelectric element 28 after this certain period of time is performed in step S2.
We will see it in 5. If oscillation has started, the process returns to step S19 and the same operation as described above is repeated. If the piezoelectric element 28 does not start oscillating even after a certain period of time has elapsed, it means that the initial setting of the toner concentration has been completed. That is, the height at which the piezoelectric element 28 starts oscillating is set by the amount of developer 16 introduced from the side channel 34. The process then proceeds to the next step 327.

In step S27, the operator is informed that the initial setting has been completed, for example, by displaying, for example, "Toner density initial setting completed" on the display 58.

FIG. 7 is a block diagram showing another embodiment of the invention. This embodiment differs from the embodiment shown in FIG. 1 in that an electronic volume 74 is used instead of the variable resistor 42. Therefore, the motor drive circuit 54 and the motor 56 for sliding the slider 42a are omitted, and the resistance value of the electronic volume 74 can be directly changed by the output of the microcomputer 50.

[Brief explanation of drawings]

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 a flow diagram for explaining the operation of this embodiment. FIG. 6 is an illustrative diagram for explaining the operation of the piezoelectric element and developer shown in FIG. 2. FIG. 7 is a block diagram showing another embodiment of the invention. In the figure, 14 is a developer chamber, 28 is a piezoelectric element, 42 is a variable resistor, 44 is an oscillator, 50 is a microcomputer, 56 is a motor, and 74 is an electronic volume. Patent applicant: Sanyo Electric Co., Ltd. agent Patent attorney Yama 1) Yoshito (and 1 other person) No. 1 Figure 2 Figure 3 Figure 4
J5 diagram

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. A toner concentration control device comprising a changing means for changing the oscillation start timing of a piezoelectric element. 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. The toner concentration control device according to claim 4, wherein the means for moving the slider includes a motor. 6. The toner concentration control device according to claim 3, wherein the variable resistance means includes an electronic volume. 7. The toner concentration control device according to any one of claims 1 to 6, comprising a switch for activating the changing means at the time of initial setting of toner concentration. 8. Claim 1, further comprising toner supply means for supplying toner to the developer chamber in accordance with the output of the piezoelectric element.
8. The toner concentration control device according to any one of items 7 to 7.