JPH1026883A - Method for measuring toner concentration and electrostatic charge amount of two-component type developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and accurately measure toner concentration and electrostatic charge amount simultaneously by sucking developer with which a unit cell is filled, discharging toner separated from carrier through a mesh, calculating the toner concentration from the decrease of the weight of the developer and calculating the toner electrified amount from charge amount. SOLUTION: A suction port unit 81 where plural suction ports are integrally molded is connected to the induction tube 23 connected to a suction pump in an airtight state. An electromagnetic valve capable of continuously switching the plural suction ports is assembled at the lower part of the unit 81, and the plural suction ports are successively switched synchronizing with the actuation of the suction pump, thereby, an effect just like the suction ports themselves are rotated is obtained. The developer with which the unit cell 1 is filled is sucked from the lower part of the mesh provided at the lower end of the cell 1, the separated toner is discharged to the outside, and the toner concentration is calculated from the decrease of the weight of the developer in the cell 1 or the weight of the discharged toner, and the toner electrostatic charge amount is calculated form the charge amount of the cell 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a toner concentration and a charge amount in a two-component developer. More specifically, the present invention relates to a method for measuring the toner concentration and the charge amount simultaneously and with high accuracy. It relates to a method that can be performed with a simple device.

[0002]

2. Description of the Related Art In the field of electrophotographic copying and facsimile, a two-component developer, that is, a mixture of a magnetic carrier (hereinafter, referred to as a "carrier") and a toner is used to visualize an electrostatic latent image. Widely used. In a magnetic brush developing method using a two-component developer, charging is performed by friction between a magnetic carrier and toner, and the charged developer slides on a photosensitive member having an electrostatic latent image in the form of a magnetic brush. Rubbing causes the toner to be attracted to the electrostatic latent image while the carrier remains on the developing roller with the magnet to perform the developing operation. The toner concentration and charge amount in a two-component developer are
Since the density, image quality, fog and the like of the formed image are significantly affected, it is very important in the field of electrophotography to perform the measurement accurately and by a simple operation.

Conventionally, the toner charge amount is measured by separating the toner from the developer by gas pressure and measuring the residual charge (blow-off method, 1-1); measuring the transfer of the charge due to development as a current, A method of calculating the charge amount of the toner particles (developing current method, 1-2); a method of measuring the toner moving speed in an electric field to calculate the charge amount of the toner particles (electric field transfer method, 1-3); Measuring the surface potential of the toner thus obtained and calculating the charge amount of the toner particles (the surface potential method,
1-4) are known. The toner concentration is measured by measuring the amount of carbon dioxide generated from the developer at a high temperature and calculating the amount of the toner from the amount of carbon (carbon analyzer method, 2-1). (Washing method, 2-2) in which the toner concentration is calculated from the weight difference by washing.

[0004]

However, in the blow-off method 1-1 of the toner charge amount measurement methods, the carrier is destroyed by the gas pressure, and the charge generated at this time is also measured. There is also the inconvenience that the toner concentration needs to be known. Also, in the developing current method of 1-2, since the current is weak, noise or the like affects,
There is a disadvantage that the measurement is unstable. Furthermore, the above 1
In the electric field transfer method of -3, it is difficult to separate and separate the toner particles one by one, and there is a problem that the apparatus is very complicated and large. Furthermore, the surface potential method of 1-4 has a disadvantage that it is difficult to obtain accuracy in measuring the layer thickness and distance of the developed toner. In the measurement of toner concentration, the carbon analyzer method of 2-1 also measures a spent toner attached to the carrier surface, which requires a preliminary test for a developer having a known concentration in order to prepare a conversion formula. However, there are disadvantages in that the apparatus becomes very large and consumables costs and measurement costs are also high. Further, in the cleaning method 2-2, there is a problem that the measurement takes a lot of trouble and time, and the measurement accuracy is not high.

Accordingly, an object of the present invention is to solve the above-mentioned disadvantages of the conventional method, to enable simultaneous measurement of toner concentration and charge amount, and to enable simple and high-precision measurement using a simple apparatus. It is an object of the present invention to provide a method for measuring the toner concentration and the charge amount.

[0006]

According to the present invention, a two-component developer is filled in a unit cell having a mesh at a lower portion, and a plurality of suction ports arranged at a lower portion of the mesh are successively switched for suction. As a result, the developer adsorbed on the mesh portion in the unit cell immediately above the suction port is moved in accordance with the switched suction port, the toner separated from the carrier is discharged out of the unit cell through the mesh, and the weight of the developer in the unit cell is reduced. There is provided a method for measuring a toner concentration and a charge amount in a two-component developer, wherein a toner concentration is calculated from a reduced or discharged toner weight, and a toner charge amount is calculated from a charge amount of a unit cell. The area of each suction port is preferably 3 to 30% of the area of the entire mesh, and the distance between the suction port and the mesh is preferably 5 mm or less.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 for explaining the measurement principle of the present invention, a unit cell 1 is mainly composed of a cylindrical side wall 2.
And an upper lid 3 and a mesh 4. An outwardly protruding flange 9 is formed at the lower end of the cylindrical side wall 2, and the mesh 4 is fixed by screws 6 using the flange 9. A substantially straight developer accommodating space 5 is formed in the cylindrical side wall 2, and the lower end of the developer accommodating space 5 is closed by the mesh 4. The upper lid 3 is provided at the upper end of the cylindrical side wall 2 so as to be openable and closable, so that the developer can be taken in and out of the developer accommodating space 5. The developer is a mixture of the carrier 10 and the toner 11, and has a size such that the mesh opening of the mesh 4 cannot pass the carrier 10 but can pass the toner 11.

[0008] A grip 7 (ring) is provided on the outer periphery of the upper portion of the cylindrical side wall 2 to facilitate carrying the unit cell 1. A vent 15 having a smaller diameter than the inner diameter of the cylindrical member 2 is provided at the center of the upper lid 3.
The vent 15 is provided with a mesh 16 for preventing powder scattering. The unit cell 1 is formed of a conductive material, particularly metal, so that the charge amount can be measured, and the meshes 4 and 16 are formed of the same material. After the developer is filled in the developer accommodating space 5 of the unit cell 1 and the upper lid 3 is closed, suction is performed from below the mesh 4. The separated toner 11 is discharged to the outside of the unit cell 1 through the mesh 4, and by continuing this operation for a certain period of time, the separation of the carrier 10 and the toner 11 is effectively performed.

In accordance with the separation and discharge of the toner, a charge of the carrier 10 is generated (residual) in the unit cell 1 and the residual charge has the same absolute value as the charge of the toner.

[0010]

(Equation 1)

Thus, the toner charge amount [μc / g] is measured. When the weight difference at this time is measured, the following equation (2) is obtained.

[0012]

(Equation 2)

The toner concentration [%] is measured from the above. still,
The weight of the absorbed toner [g] is expressed by the following formula (3).

[0014]

(Equation 3)

## EQU1 ## The switchable suction port in the present invention is, for example, a suction port unit 81 as shown in FIG. 2, and a plurality of suction ports 2 as shown in FIG.
1 is integrally formed and connected in a confidential state to the guide tube 23 connected to the suction pump 42 (FIG. 5) through the pressure-resistant tube 33. A solenoid valve capable of continuously switching a plurality of suction ports is incorporated in a lower portion of the suction port unit 81, and a switching machine sequentially switches the plurality of suction ports 21 in accordance with the operation of the suction pump 42, as if it were. ,
This has the effect that the suction port 21 itself is rotating. A switchable suction port other than those described above can be suitably used as long as the carrier and the toner do not stay at a specific location when the developer is separated.

Although the area of each suction port depends on the type of developer to be separated, the amount of charge, and the like, an area of 3 to 30%, particularly 5 to 25% of the area of the mesh 4 is preferably used. . If the individual area of the suction port is smaller than 3% of the area of the mesh, it takes a long time to separate the toner from the carrier, and there is a tendency that quick measurement cannot be performed. Also,
If it is larger than 30%, the effect of switching the suction port to efficiently separate the developer, which is a feature of the present invention, tends to decrease. Also, the area of each suction port does not need to be the same, and if the developer is efficiently separated,
The areas of the suction ports may be different. The shape of the suction port is not particularly limited. In addition to the circular shape shown in FIG.
Various shapes such as a square shape can be used, and shapes having different shapes may be combined.

The distance between the opening of the suction port and the mesh may be any distance as long as the developer can move according to the switched suction port. Specifically, the distance between the mesh 4 and the opening is 5 m
m or less and 1 to 5 mm, preferably 2 to 4 mm, in consideration of the deflection of the mesh 4 due to suction. The distance between the opening of the suction port 21 and the mesh 4 is 5 m.
If it is larger than m, the developer tends not to move even when the suction port 21 is switched. The vent 15 is preferably covered with a mesh 16 so that the developer, the separated carrier 10 and the toner 11 do not escape from the vent, and the charge of the developer does not escape. If not, use a position where the developer does not
In addition, in order to prevent charges in the unit cell from escaping from the cell, it is desirable that the hole diameter of the vent hole 15 is one third or less of the distance (height) from the mesh 4 to the vent hole 15. . The number of vents 15 is not particularly limited, and may be one or a plurality of vents. The position where the vent is provided is the top lid 3,
Either one or both of the cylindrical side walls 2 may be used. In addition, the carrier 10 and the toner 11 can be provided without providing a vent.
Is possible.

In the present invention, as described above, the toner density T / D and the toner charge amount Q / M can be measured simultaneously by a single operation using a common measuring device, and the toner density and the composition can be measured. Has the advantage that both the density and the charge amount can be measured from an unknown developer. Moreover, according to the present invention, there is an advantage that the toner concentration and the charge amount can be measured with simple means and with high accuracy. FIG. 3 shows the results of measuring the toner concentration of a two-component developer having a known toner concentration (T / D) by the known carbon analyzer method (△) and the suction method (■) of the present invention (the details will be described later). Reference). According to FIG. 3, the toner density value according to the sample density is obtained, and it is understood that the accuracy is high. It can be seen that the present invention is practically superior in terms of simplicity of the device and operation.

FIG. 4 shows the results of measuring the charge amount of a two-component developer having a known toner concentration (T / D) by a known blow-off method (△) and a suction method (■) of the present invention (details will be described later). See the example below). The blow-off method and the method of the present invention have the same purpose in that the toner is separated and the charge amount is measured.However, the blow-off method requires a considerably high gas pressure to cause carrier destruction. Has been confirmed. It is considered that, due to the carrier destruction, positive or negative extra charge is generated depending on the agent. On the other hand, in the present invention, since the suction method is used, compared with the blow-off method, the developer is separated under a mild environment for the developer,
Carriers are not easily destroyed, and in fact, it has been confirmed by electron microscope observation that carrier destruction has not occurred. Although the separation is performed under mild conditions, the carrier and the toner can be completely separated by moving the developer on the mesh according to the movement of the suction port as described above.

In the apparatus using the measuring method of the present invention, a hollow unit cell support is provided in an airtight and electrically insulated state above the suction chamber, and the unit cell is detachably supported on the support. With this configuration, not only the operation of charging and removing the developer into and from the unit cell can be easily performed, but also the weight of each unit cell can be measured, and the suction operation and the measurement of electric charge can be performed simply by mounting the unit cell on the support base. Is also possible. The unit cell and the support are preferably formed of a metal material having a work function difference of 0.60 eV or less, particularly, the same metal material. Work function difference is 0.60
If the voltage exceeds eV, the developer is charged into the unit cell and contact charging occurs when the unit cell is placed on the support table, so that the Faraday cage is charged. Due to the potential difference generated at this time, the separated toner remains on the mesh, making it impossible to accurately measure the charge amount.

[0021]

FIG. 5 shows an example of the overall arrangement of a measuring apparatus used in the present invention.
Main body control unit 41, suction pump 42, charge meter 4
3 and a balance 44. In FIG. 2 showing a detailed structure of the measuring device main body 40, a table 30 made of, for example, stainless steel (SUS) is provided at a lower portion of the main body 40.
And a housing (shield case) 31 also made of stainless steel is provided on the base 30. A suction chamber 32 having an upper opening is provided in the housing 31. A suction unit 81 having a plurality of suction ports 21 is disposed in the suction chamber 32.
3. Suction pump 42 via pressure-resistant tube 33 (FIG. 5)
It is connected to the. An air pressure sensor 34 is disposed in the guide tube 23, and a detection signal thereof is supplied to the above-described main body control unit 41 by a cable 35.

A unit cell accommodating space 36 is provided above the suction chamber 32, and a unit cell support 37 serving also as an electrode is provided at a boundary between the accommodating space 36 and the suction chamber 32. The support base 37 is also formed of stainless steel, and is fixed to the housing 31 by embedded bolts 38 formed of an electrically insulating material (resin). A ring-shaped electric insulating material (silicone rubber) 39 is fitted between the support 37 and the housing 31, and the support 37 is provided on the main body 40 in an airtight and electrically insulated state. I have. The support base 37 is connected to the charge meter 43 via the internal wiring 70, the connector 71, and the cable 72. A lid 74 is provided on the upper part of the unit cell housing space 36 so as to be openable and closable,
The lid 74 is provided with a vent 76 having a mesh (37 μm) 75 to keep dust out.

Returning to FIG. 5, the operation panel of the main body control unit 41 includes a power switch 50, a start button 51, a stop button 52, a suction force adjustment knob 53, a digital barometer 54, a timer 55, and a switching speed adjustment knob. 56 are provided. The start button 51 and the stop button 52 are for driving the suction pump 22 to start measurement, and for stopping the suction pump 22 to end the measurement. The timer 55 sets a measurement time and stops the pump 42 at the set measurement time. The suction force adjusting knob 53 is for controlling the power supplied to the suction pump 42 by a gate control type semiconductor switch. On the other hand, the digital barometer 54
Indicates the atmospheric pressure detected by the atmospheric pressure sensor 34 (FIG. 2). By turning the suction force adjusting knob 53, the pressure in the suction port unit 81 (FIG. 2) is set to an arbitrary value. be able to.

The switching speed adjustment knob 56 adjusts the speed at which the movable suction port is switched. By rotating the switching speed adjustment knob 56, the speed at which each suction port is switched can be arbitrarily set. The suction pump 42 reduces the pressure of the suction chamber 32 (FIG. 2) to a predetermined pressure and collects the discharged toner particles. The suction pump 42 has a vacuum degree of 300 to 1200 mm, a water column of 0.01 to 1000 mm. One having a toner collection paper pack of 1.00 m ³ / minute is preferably used. The pump used in this embodiment is a toner cleaner, more specifically, CV-TN95 manufactured by Hitachi, Ltd. Charge meter 4
Numeral 3 is for measuring the charge of the residual carrier, that is, the charge of the toner via the support base electrode 37 (FIG. 2). A charge meter having a measurement range of up to 20 μC is used. The charge meter used in this embodiment is a digital electrometer TR8652 manufactured by Advantest Co., Ltd. and a coulomb range extender R12601 (necessary only when the measurement range is extended).

The balance 44 measures the weight of the developer or the residual carrier for each unit cell. Since the amount of toner to be sucked is as small as about 0.01 to 0.05 g, the balance 44 is used. It has a precision of more than an order of magnitude. In this example, a reading limit of 0.1 mg was used with Shimadzu Corporation's Aigara electronic balance AEG-320. In the measurement of the toner concentration and the charge amount, the measurement conditions vary considerably depending on the type of the carrier, the type of the toner, and the combination of the two, and thus cannot be unconditionally specified. However, as a standard condition, the suction pressure is -6 kPa to -6 kPa. -13 kPa, a suction time of 20 to 60 seconds, and a developer sample amount of 0.4 to 1.0 g are appropriate. The area of the mesh part is 3 to 20 cm ^2, and the volume of the developer accommodating part is 6 to 7 cm.
0 cm ³ is appropriate. Furthermore, the opening degree of the mesh part is 3
Those having a thickness of 7 μm are preferably used.

That is, if the degree of the pressure reduction is too small or the time is short, the separation of the toner and the carrier is incomplete and the toner concentration T / D is low, or the toner charge amount Q / M tends to vary. Conversely, if the degree of decompression is too high or the time is too long, a part of the carrier is peeled off and T / D becomes high, or Q / M tends to fluctuate due to extra charging in the cell. There is. Of course, it is needless to say that for a developer containing a fragile carrier or a toner that is difficult to separate, the optimum range should be set by changing the degree and time of the pressure reduction. If the sample amount of the developer is larger than the above range, the separation of the toner from the carrier becomes insufficient. On the other hand, if the sample amount is smaller than the above range, the toner amount becomes minute and the accuracy is lowered, which is not preferable.

In this embodiment, the measurement was performed in the following procedure. 1. Weigh the unit cell weight. ... A [g] Put the sample in the unit cell. 3. Weigh the unit cell containing the sample. ... B [g] Set the unit cell in the device. 5. Release the charge meter hold and reset to zero. 6. Press the start button to start suction. 7. When stopped, hold the charge meter and read the value. ... C [μC] Weigh the unit cell weight. ... D [g] 9. Clean the unit cell. Calculation

[0028]

(Equation 4)

[0029]

(Equation 5)

The unit cell is a stainless steel cell having a mesh part diameter (D ₂ ) of 40 mm, an upper opening diameter (D ₁ ) of 12 mm, a height (H) of 30 mm and a weight of 155 g (with a 37 μm stainless steel wire mesh). It was used. Further, as standard measurement conditions, a suction pressure of -9 k
Pa, a suction time of 30 seconds, and a sample amount of 0.4 to 1 g were used. As an example, an electrophotographic copying machine D manufactured by Mita Kogyo Co., Ltd.
Using a developer for C-2556, the toner and the magnetic carrier are accurately measured, and ball milling is performed to prepare a two-component developer having a toner concentration of 2 to 5%. The toner density and the charge amount were measured under the conditions that the height was 30 mm and the switching period of the suction port was 40 times per minute. For comparison, measurement of toner concentration by a known carbon analyzer method and measurement of toner charge amount by a blow-off method were also performed. FIG. 3 shows the obtained results.
And FIG.

[0031]

According to the present invention, there is an advantage that the toner concentration and the charge amount can be simultaneously measured within a short time by a single suction operation using a common measuring device. Further, the toner concentration and the charge amount can be measured with a simple device and means.
In addition, there is an advantage that the measurement can be performed with high accuracy, and the apparatus cost and the running cost are low. Further, since no conversion formula is required, the toner concentration of the developer whose concentration and composition are completely unknown can be measured, and the concentration value is not affected by the spent toner.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining a measurement principle of the present invention.

FIG. 2 is a cross-sectional view showing details of a measurement device main body.

FIG. 3 is a graph showing the results of measuring the toner concentration of a two-component developer having a known toner concentration (T / D) by a known carbon analyzer method (△) and a suction method (■) of the present invention.

FIG. 4 is a graph showing the results of measuring the charge amount of a two-component developer having a known toner concentration (T / D) by a known blow-off method (△) and a suction method (■) of the present invention.

FIG. 5 is a layout view showing the entire measuring device used in the present invention.

FIG. 6 is a top view of a suction port unit used in the present invention.

[Explanation of symbols]

 Reference Signs List 1 unit cell 2 cylindrical side wall 3 lower lid 4 mesh (37 μm) 5 developer accommodating space 6 screw 7 gripping part (ring) 9 flange 10 carrier 11 toner 15 vent 16 mesh 21 suction port 23 guide tube 24 power unit 30 (Stainless steel) 31 Housing (Stainless steel) 32 Suction chamber 33 Pressure-resistant tube 34 Atmospheric pressure sensor 35 Cable 36 Unit cell accommodation space 37 Unit cell support base (Stainless steel) 38 Electrical insulating member (embedded bolt) 39 Electrical insulating member (Ring silicone rubber) 40 Measurement device main body 41 Main body control section 42 Suction pump 43 Charge meter 44 Balance 50 Power switch 51 Start button 52 Stop button 53 Suction force adjustment knob 54 Digital barometer 55 Timer -56 Switching speed control knob 70 Internal wiring 71 Connector 72 Cable 74 Lid 75 Dust shield (37 μm) 76 Vent (φ10) 81 Suction port unit

Claims (3)

[Claims] 1. A unit cell having a mesh at a lower portion is filled with a two-component developer composed of a magnetic carrier and a toner, and suction is performed by sequentially switching and sucking from a plurality of suction ports arranged at a lower portion of the mesh. The developer adsorbed on the mesh portion just above the mouth is moved in accordance with the switched suction port, and the toner separated from the magnetic carrier is discharged out of the unit cell through the mesh, so that the weight of the developer in the unit cell is reduced or the discharged toner is discharged. A method for measuring a toner concentration and a toner charge amount in a two-component developer, wherein a toner concentration is calculated from a weight and a toner charge amount is calculated from a charge amount of a unit cell. 2. The method according to claim 1, wherein the area of one suction port is set to 3 to 30% of the area of the mesh. 3. The method according to claim 1, wherein the distance between the suction port and the mesh is set to 5 mm or less.