JPS58121072A - Toner density detecting device - Google Patents

Abstract

PURPOSE:To detect loading of a developer, by detecting fluidity of the developer or magnetic permeability by a piezoelectric element. CONSTITUTION:In a sub-circulating path which has made a part of a developer in a developer main circulating path branch by a branching plate 9, a piezoelectric element 10 is provided. Fluidity of the inside of this sub-circulating path is varied remarkably by a variation of a coefficient of friction when a characteristic of toner density is varied. Relation of toner density and fluidity is constituted so that fluidity becomes high when toner density is low, that is to say, when there are a lot of carriers, and fluidity becomes low as toner density becomes high. As for pressure and fluidity of the developer to the piezoelectric element, as fluidity becomes high, pressure becomes high, as well. Accordingly, from pressure of the developer, toner density is known. When toner density is varied, magnetic permeability is also varied, and chaining force of a magnetic brush is also varied, therefore, pressure which the piezoelectric element 10 receives is also varied.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner concentration detection device for use in electrophotographic copying machines, electrostatic copying machines, and the like.

As is well known, in the case of IJW development on a latent image carrier using a two-component developer.

It is the toner that directly contributes to the dust phenomenon, and it has the role of triboelectrically charging the carrier (etoner) and supporting r'L. As a result, the proportion of toner in the developer, that is, the toner concentration, decreases each time development is performed.
Is this the toner concentration detected? You will need to find ways to keep it constant.

There are various methods for detecting toner concentration. Among these, a method that detects the toner performance based on a change in the flow rate of dust particles is disclosed in Japanese Patent Laid-Open No. 54-50340. This is due to #t (change in toner # degree of IJ agent).

It takes advantage of the fact that the flow of developer (that is, the amount of developer flowing per unit time/area changes).

Some developer drawn from the developer circulation path? What is the change in magnetic permeability when a coil is passed through a wound bobbin? to detect the toner density. Namely.

When the fluidity of the agent changes, the effective magnetic permeability of the agent also changes, and this change in magnetic permeability is interpreted as a change in the inductance of the coil, and the change in the oscillation frequency in the oscillation circuit is detected to detect the toner concentration. . This method has the advantage of higher sensitivity and higher detection degree than other methods. However, there is a certain amount of #1 in the bobbin. The lower orifice of the hopper, which is used to safely supply the cleaning agent, is filled with developer'1! There are some drawbacks. Orifice diameter?
It's a big deal.

Although such clogging of the 4@ agent is eliminated, the amount of current passing through the bobbin increases accordingly, so it is necessary to increase the amount of supply to the hopper, which requires a complicated structure and space.

The toner concentration detection device according to one embodiment of the present invention is configured to conduct a part of the developer agent from the developer circulation path in the developing device. A developer branching member for forming, a piezoelectric element disposed in the developer sub-circulation path, and a signal from this piezoelectric element is amplified to determine the reference toner # degree? and a detection circuit that outputs a signal compared with a representative reference value. In another embodiment of the present invention, the piezoelectric element is placed in pressure contact with the magnetic brush at a position outside the visible area of the magnetic brush formed on the developing roller. In yet another variation of the invention, the piezoelectric element receives a developer as described above.
It is placed at the bottom of a bobbin with a coil wound around it, and is used as a clogging alarm.

A principal object of the present invention is to provide an improved detection device for detecting ditoner concentration by measuring developer fluidity or magnetic permeability.

Another object of the present invention is to provide the above-mentioned device capable of preventing developer clogging.

Yet another object of the present invention is to provide the above-mentioned apparatus for detecting developer flow and streak permeability using a piezoelectric element.

Yet another object of the present invention is the above-described device for detecting developer clogging using a piezoelectric element. It is about providing.

These and other objects of this invention are described in the drawings. It will become clear from the referenced explanation below.

Fig. 1 is one form of the toner concentration detection device according to this invention? An outline of the developing device provided is shown in FIG. A two-component developer 2 consisting of a magnetic carrier and a resin toner is disposed in a certain amount in a developer container l. This developer 2 (
The carrier and toner are agitated by the stirring blade 3 which rotates once more, and the carrier and toner are charged by friction, so that the toner having a small particle size adheres around the carrier having a large particle size. A pumping sleeve 4 is located at the bottom of the current waste container 1, and a developing sleeve 5 is located above the pumping sleeve 4.
Each of them is arranged so as to be rotatable n, and a plurality of magnets 6 and 7 are each arranged stationary at a predetermined position inside the magnet. The toner-adsorbed carrier is absorbed onto the surface of the sleeve 4 by the magnet 6 inside the scooping sleeve 4 to form a magnetic brush, is conveyed upward by the rotation of the sleeve 4, and is transferred to the developing sleeve 5. Photosensitive drum 8
- comes into contact with the electrostatic latent image on the photoreceptor drum 8 at a position close to .

This phenomenon occurs when toner, which is colored fine particles, is electrostatically attracted to the electrostatic latent image. The developer on the developing sleeve after development is free from dust [falls naturally from the developing sleeve 5 at a position where it escapes from the magnetic force of the magnet in the elephant sleeve 5,
The impeller 3 stirs the developer together with the developer 2 in the developer container 1 again. This is the main slag circulation path in the slag equipment.

The toner concentration detection device provided in this developing device consists of a branch plate 9 provided diagonally in the flow path of the developer falling off from the developing sleeve 5 after development, and a piezoelectric element disposed on the lower extension of the branch plate 9. 10. A part of the developer in the #L team cleaning agent circulation path is branched off by this branching plate 9 to form a subcirculation path, and in this subcirculation path, the #1. A piezoelectric element IO is provided. #1 in the main circulation path. Except for the parts that come into contact with the S agent, the stains and toner (changes corresponding to changes in yellowness) cannot be changed. This is because the circulation is forced to a certain speed.

However, if the branch plate 9 is provided to create a subcirculation path,
The flow rate in this subcirculation path is determined by the change in toner concentration.
1. It changes significantly due to changes in the characteristics of the image agent. The reason for this is a change in the coefficient of friction between the developer and the branching plate 9, and a change in the internal friction angle of the developer.

The length of the branching plate 9 in the axial direction of the developing sleeve is considerably shorter than the length of the imaging sleeve 5 in the axial direction, as shown in FIG. The remaining phenolic agent flows down from the side of the branching plate 9.

The relationship between toner concentration and fluidity is as shown in Figure 3.
When the toner concentration is low, that is, when there is a lot of carrier,
Does the flow rate decrease as the flow rate increases and the toner concentration increases? It's becoming a sea urchin. On the other hand, as shown in FIG. 4, the pressure of the slag agent on the piezoelectric element 10 increases as the flow rate increases. therefore.

If the pressure applied to the piezoelectric element is high, the toner concentration will be low, as shown in FIG. 5, and if the pressure is low, the toner concentration will be high. By using such correlation,
It becomes possible to estimate the toner concentration from the pressure of the falling developer that the piezoelectric element 10 receives.

As shown in FIG. 1, an amplifier 11 is connected to the piezoelectric element 10, and the n1 piezoelectric element 10 receives #1. Pressure changes due to changes in the fluidity of the cleaning agent are converted into electrical signals and input to the amplifier 11 at n. The amplified signal in the amplifier 11 is compared by the comparator 13 with the reference value from the generator 12, which generates a reference signal voltage brought about by the flow rate in the case of the reference toner #, and the density is determined by the magnitude of the toner. If it is low, either replenish the toner manually or replenish the toner via the driver 14! 1
A predetermined amount of toner is supplied into the developing container 1 from the piezoelectric element 10 and outside the developing area of the magnetic brush on the image sleeve 5, and the toner concentration is controlled so as to meet the standard. For example, as shown in FIG. 6, it can be provided at a position on the outside of the developing sleeve facing the magnet 7a in the developing sleeve 5 so as to be in pressure contact with the magnetic brush. The lines of magnetic force due to the magnet 7a are as follows.

As shown in FIG. 7, the magnetic lines of force spread outward from the developing sleeve 5, and the carriers in the developer are chained together to form a magnetic brush.

Among the lines of magnetic force, the line of magnetic force on the line connecting the s% of the magnet 7a and the bottom is the strongest, so the piezoelectric element 10' is placed on that line.
Place it perpendicular to that line. The distance t between the detection surface of the piezoelectric element 10 and the surface of the developing sleeve 5 is larger than the distance m, J: between the tip of the doctor 16 and the surface of the developing sleeve 5 shown in FIG. This is to avoid affecting the grain control effect of the magnetic bluff by 16.

314 due to changes in toner density. The magnetic permeability of the cleaning agent will also change, which will change the chain force of the magnetic brush, and therefore the pressure experienced by the piezoelectric element 10 will also change. Therefore, an electric circuit as shown in FIG. 1 is connected to the piezoelectric element 10,
By detecting the pressure applied to this, the toner concentration can be determined by
Ao, this can be controlled. These relationships are similar to those in which the fluidity on the vertical axis in FIG. 3 and the fluidity on the horizontal axis in FIG. 4 are replaced with magnetic permeability. Therefore, in FIG. 3, the higher the toner concentration, the lower the magnetic permeability, and in FIG. 4, the lower the magnetic permeability, the lower the pressure.

In the above two embodiments according to this invention.

The toner concentration is determined and controlled by changing pressure/electricity using a piezoelectric element that changes fluidity or magnetic permeability, which are correlated with changes in toner concentration. Therefore, clogging of the developer does not occur structurally, and good toner concentration detection can be performed at all times.

In yet another embodiment of the invention shown in FIG. 8, the piezoelectric element 10 is not used for toner concentration detection;
It is used to detect clogging of the developer case in a toner density detection device. The toner concentration detection device itself in this embodiment (Japanese Unexamined Patent Publication No. 54-50, written by A+J)
This is the same as that described in Publication No. 340, and the electrostatic latent image on the photoreceptor drum 8 is the same as that described in Publication No. 340. The developer on the dusty sleeve 5 is scraped off by the scraper 17, and some of the developer is guided into the hopper 18 in the falling flow.
9? The material passes through the wound bobbin 20 and is collected into the container 1. The flow rate of the developer flowing down from the lower orifice of the hopper 18 changes due to a change in fluidity due to a change in toner concentration, and the effective magnetic permeability within the bobbin 20 changes.

This change in magnetic permeability is taken as a change in the inductance of the coil 19, and V is detected by the detector 21 as a change in the oscillation frequency in the LC oscillation circuit.

A reference voltage generator 22 representing the output reference toner concentration
The comparator 23 compares the output from the toner replenishing device 25 (7) with the comparator 23, and depending on the magnitude, the driver 24 controls the toner replenishing device 25 (7) toner output.

The toner concentration of the developer in the developer container 1 is controlled.

The piezoelectric element 10 is disposed directly below the bobbin 20 and slightly inclined at a position above a reference storage level of the developer 2 in the developer container l. If the developer is flowing down normally from the lower orifice of the hopper 18, the piezoelectric element 10
Since the developer hits the piezoelectric element 10 and applies pressure, a voltage is generated in the piezoelectric element 10. When the developer clogs the orifice and stops flowing down, the output voltage from the piezoelectric element 10 decreases. In this case, the reason why the output voltage does not become zero is due to developer remaining on the piezoelectric element or noise.

The output voltage from the piezoelectric element 10 is amplified by an amplifier 27, and then a reference voltage generator 28 generates a voltage slightly lower than the value output from the amplifier 27 when the developer is flowing down. The comparator 29 compares the voltage from the amplifier 27 with the voltage from the amplifier 27, and if the signal value from the amplifier 27 is lower than the reference value, a warning 30 that the developer amount is 1 is issued by a display or a buzzer.

In this way, clogging is detected, so in that case, the operation of the copier in which this developing device is mounted is checked.
The hopper 18 can be stopped and the hopper 18 energized to eliminate clogging, or such an operation can be automatically performed in conjunction with the energization warning 30.

[Brief explanation of the drawing]

FIG. 1 is an embodiment of the toner detection device of the present invention. FIG. 3 is a schematic diagram showing a developing device. A diagram showing the positional relationship between the second copper stripe, the developing sleeve and the piezoelectric element in the developing device shown in FIG. 1, and FIG. 3 is a diagram showing the relationship between toner # degree and developer flow rate. FIG. 4 is a diagram showing the relationship between the developer flow regime and the pressure applied to the piezoelectric element, and FIG. 5 is a diagram showing the relationship between the pressure applied to the piezoelectric element and toner concentration. FIG. 6 is a schematic diagram of a dust one-image device having another embodiment of the present invention. FIG. 7 is a diagram showing the positional relationship between the magnet and the piezoelectric element in the dust device shown in FIG. 6; FIG. 8 is a schematic diagram of a current military equipment equipped with yet another embodiment of the present invention. 1... Developing container, 2... Two-component dust acid agent, 3... Impeller, 4... Pumping sleeve S 5... Developing sleeve, 6.
7... Magnet, 8... Photosensitive drum, 9
...Branch plate, 1o...Piezoelectric element tree 4 diagram (rental, Z = 19.4'-n)

Claims (1)

[Scope of Claims] l A device for detecting the toner concentration of a two-component developer, which detects a part of the developer from a developer circulation path in a developing device. and a developer branching member for guiding the developer to form a developer sub-circulation path. A toner concentration detection device 2 comprising: a piezoelectric element disposed in the developer subcirculation path; and a detection circuit that amplifies a signal from the piezoelectric element, compares it with a reference value, and outputs the signal; 2. The toner concentration detection device according to claim 1, further comprising a toner replenishing device for replenishing toner into the developing device in accordance with an output signal. 3. A device for detecting the degree of toner in a two-component developer, comprising: a piezoelectric element placed in pressure contact with the magnetic brush at a position outside the dust area of the magnetic bluff formed on the developing roller; , amplify the signal from the piezoelectric element and compare it with a reference value to determine the signal? Toner concentration detection device including output detection circuit and ge. 4 Toner flows into the current 1 wall device according to the output signal from the detection circuit? 4. The toner concentration detection device according to claim 3, further comprising a toner replenishing device for replenishing toner. 5 A device for detecting the toner concentration of a two-component developer, wherein #1 in the developing device. a bobbin wound with a coil for guiding some of the developer from the III agent circulation path and passing it therein; a toner concentration detection circuit connected to the coil; and a developing device located below the bobbin. a piezoelectric element located above the surface of the developer stored in the bobbin and in contact with the developer flowing down in the bobbin; A toner concentration detection device including another detection circuit that amplifies the signal from the HiJ piezoelectric element, compares it with a reference value, and outputs a signal. 6. The toner temperature detection device according to claim 5, further comprising a toner replenishing device for replenishing toner into the C developing device in response to an output signal from the toner #degree sensing circuit.