JP3112904B2 - Apparatus and method for measuring triboelectric charge of powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge amount measuring apparatus and method for measuring the amount of triboelectric charge generated between a sample powder and a friction partner powder accurately, quickly and simply.

[0002]

2. Description of the Related Art In order to measure the triboelectric charging characteristics of a sample powder, conventionally, a sample powder and a friction partner powder to be charged are mixed and sufficiently friction-charged in advance, and then the wind power,
A method has been adopted in which the two are separated by centrifugal force, mechanical force, impact force, electrostatic force, vibration, or the like, and the amount of charge remaining on one of the separated powders is measured. This separation of the sample powder and the friction partner powder is performed by separating the particle size through a wire mesh when there is a difference in particle size between the sample powder and the friction partner powder. When one of the partner powders is a ferromagnetic material, it can be adsorbed and separated by a magnet.

[0003] As described above, a method of removing a small particle size powder by passing through a wire mesh and collecting only a large particle size powder is called a blow-off method and is most commonly used. . In this method, a sample powder and a friction partner powder are mixed sufficiently in advance in a metal conductive container having a wire mesh stretched over at least one opening end opened on the inflow side and the discharge side of the airflow. After charging after friction charging, by blowing compressed air from the gas inflow side to the discharge side wire mesh surface,
The powder having a small particle diameter is blown off through a wire mesh and removed, and the powder having a large particle diameter remaining in the conductive container is collected.
When the removed small-diameter powder is taken away, an equivalent amount of charge remains on the surface of the large-diameter powder remaining in the conductive container in this manner. It becomes possible to know the charge amount.

A similar effect can be obtained by sucking from the gas discharge side instead of blowing the compressed air from the gas inlet side of the conductive container.

[0005]

However, although the apparatus using the conventional blow-off method can easily and quickly and accurately know the triboelectric charging characteristics, it has the following problems in measuring the amount of charge.

First, the sample powder and the friction partner powder separated in the conductive container are electrostatically attracted to each other to unite again and repeat contact and separation a plurality of times. work. As a result, it takes time to stabilize the measured charge value, and it is difficult to perform quick measurement.

Second, when the sample powder and the friction partner powder are frictionally charged between the wall surface and the wire mesh of the conductive container by the blow-off operation, the frictional charge generated by the friction between the two powders Will be different.

Third, since the separated powder easily adheres to the inner wall of the conductive container or a part of the wire net, an error occurs in the measured charge amount.

Fourth, an error occurs in the measured charge amount due to the charging caused by the friction of the large particle size powder on the surface of the wire mesh.

Fifth, as the amount of triboelectric charge between the sample powder and the friction partner powder increases, not only does it take time to separate, but in some cases, separation is not possible.

Accordingly, the present invention has been made in view of the above-mentioned problems, and controls the flow of gas from the gas inflow side to the discharge side of the conductive container so that the sample powder and the friction partner powder can be separated. The purpose is to increase the separation effect.

[0012]

In order to achieve the above object, an apparatus for measuring the amount of triboelectric charge according to claim 1 is provided in which a triboelectrically charged sample powder and a friction partner powder are placed in a conductive container having a wire mesh stretched. And the mixed powder is separated into the sample powder and the friction partner powder by an air current, and only the sample powder having a small particle diameter of the mixed powder is discharged through the wire mesh. In a powder triboelectric charge measuring device for measuring the charge of a large-diameter particle friction partner powder remaining in the wire netting, a gas outlet for blowing a compressed gas into an upper end portion and a gas around the gas outlet are provided. provided with a gas inlet for introducing a cylindrical conductive container having an opening to the gas suction port for sucking the compressed gas to the lower portion, and the gas inlet of the conductive container of the gas suction port It is stretched between, and the sample powder accommodated in the conductive container and Shape and wire mesh for selectively passing the sample powder with suction and blowing of the compressed gas out of the friction partners powder, an opening for flowing gas in a horizontal direction on the lower surface outer peripheral portion of the gold network
Adult City, sucks the vortex generating means for the gas from the opening and flows toward the wire mesh surface to generate a vortex, the compressed gas ejected from the blowing port of the upper end of the conductive container at the bottom of the wire mesh Gas suction means, remaining in the conductive container
And a charge amount measuring means for measuring a charge amount of the friction partner powder .

According to the apparatus for measuring the amount of triboelectric charge of a powder according to the present invention, the air flow in the apparatus for measuring triboelectric charge is controlled by the friction band.
Suction from the lower part of the coulometer by the gas suction means
And an opening of the vortex generating means derived by the suction
Gas flowing horizontally along the underside of the wire mesh from the front
The gas flowing from the gas inlet of the conductive container and the friction
Blowing of compressed gas from the gas outlet on the top
It is composed of a combined airflow with the airflow caused by the intrusion . Also, the charge amount
At the time of measurement, the conductive volume is previously measured by the gas suction means.
Gas from the gas inlet of the vessel and the opening of the vortex generator.
Into the gas outlet while maintaining the state.
The compressed gas will be blown.

According to a second aspect of the present invention, there is provided a method for measuring a triboelectric charge amount of a powder.
Gas outlet for injecting compressed gas into upper end and gas outlet
A gas inlet for introducing gas is provided around the
Providing a gas suction port for sucking the compressed gas and
A wire mesh is stretched between the gas inlet and the gas suction port
At the bottom of the cylindrical conductive container, the horizontal direction of the conductive container
Vortex generator with an opening for gas flow
And passing through the wire net frictionally charged in the conductive container.
Sample powder of small particle size obtained and friction of larger particle size than said sample powder
The mixed powder with the counterpart powder is stored, and the gas in the conductive container is
Suction from the suction port and gas inlet and vortex of the conductive container
The wire mesh is caused by the gas flow flowing from the opening of the flow generating means.
A gas swirl is formed in the lower part to mix the powder mixture with the wire mesh.
Uniformly distributed on the surface, and then gas ejection from the conductive container
By blowing compressed gas through the mouth,
The metal mesh is used to separate only the sample powder while separating the friction partner powder.
Through the wire mesh, and then the friction partner left in the wire mesh
The charge amount of the powder is measured .

According to a second aspect of the present invention, there is provided a method for measuring a triboelectric charge amount of a powder.
If it is, conductive in the conductive container by gas suction means in advance
Gas from the gas inlet and the opening of the vortex generator
While maintaining the state,
The gas is sucked from the suction port and the opening of the vortex generator.
First, gas is introduced into the conductive container, and pressure is
By blowing compressed gas toward the wire mesh,
Generates vortex and separates into sample powder and friction partner powder
Only the sample powder with a small particle size out of the mixed powder is passed through a wire mesh.
To remove the large-diameter grain friction partner powder remaining in the wire mesh.
The charge amount can be measured.

[0016] Delete

[0017] Delete

[0018] Delete

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 show an embodiment of the present invention. FIG. 1 is a sectional view of a device for measuring the amount of triboelectricity of powder, FIG. 2 is a sectional view showing a wire mesh holder and a vortex generating nozzle, and FIG. FIG. 4 is a front view of the opening of the eddy current generating means, FIG. 4 is a perspective view showing a state where a wire mesh holder is incorporated in a conductive container (hereinafter referred to as a Faraday cage), and FIG.

As shown in FIG. 1, the apparatus for measuring the amount of triboelectric charge of a powder according to the present invention has a Faraday cage 1 disposed substantially at the center thereof. The Faraday cage 1 is made of a conductive material (generally, stainless steel, Copper, brass, aluminum, iron, etc.
Alternatively, it may be formed of plastic and the inner surface thereof is plated with nickel, chromium, gold, platinum or the like which is stable against oxidation.
And a cylindrical container provided with an opening 16 on the gas inflow side.

A wire mesh holder 3 is provided on the lower surface, that is, on the gas discharge side. The wire mesh holder 3 has a fitting portion 3a into which the outer diameter of the Faraday cage 1 is fitted as shown in FIG.
An opening 3b having the same diameter as the inner diameter 1a of the discharge side opening of the Faraday cage 1 is formed at the center, and a bottom 3c of the fitting portion 3a is formed.
The wire mesh 2 (for example, made of stainless steel) is inserted into the
Can be held down and fixed by the Faraday cage 1.

On the other hand, as shown in FIGS. 2 and 3, on the lower surface of the wire mesh holder 3, an eddy current generating opening 13 is formed as eddy current generating means. This vortex generation opening 13
Is an approximately arc-shaped or triangular-shaped air flow guide section 14 having a height H of 1 mm, which is formed at three or six places at equal intervals. The gas flow guide portion 14 can generate a vortex by flowing or sucking the gas from the three or six locations on the outer peripheral side of the Faraday cage 1 along the lower surface of the wire mesh 2 while rotating the gas.

The shape of the air flow guide portion 14 is not limited to a substantially arc shape or a triangular shape, but may be a straight line shape or any other shape. Good. The arrangement is not limited to three places, but may be three or more places.

Below the wire mesh holder 3, a Teflon base 7, which is a cylindrical body of an insulator, is provided. The inner diameter of the Teflon stand 7 is the same as the inner diameter 1a on the discharge side of the Faraday cage 1 and the inner diameter 3b of the wire mesh holder 3, and the Faraday cage 1 in which the wire mesh holder 3 is inserted on the upper surface of the Teflon stand 7 is placed. In this case, the inner diameters of the Faraday cage 1, the wire mesh holder 3, and the Teflon table 7 can be communicated with the same diameter. Further, a suction system 11 is connected below the Teflon base 7, and a suction device (not shown) is connected to a terminal of the suction system 11 as suction means.

On the other hand, above the Faraday cage 1, an upper nozzle 10 which is a compressed gas jet port connected to a pressure hose 12 for blowing compressed gas is disposed via a mounting table 15, and the mounting table 15 is The side is opened, and the gas is freely sucked into the Faraday cage 1 from the opening 16 by the operation of the gas suction means.
Compressed gas is blown from the upper nozzle 10.

The powder for which the amount of triboelectric charge is measured by the apparatus having the above-mentioned configuration is a combination of one of the sample powder 4 and the friction partner powder 6 having a particle size larger or smaller than the mesh of the wire mesh 2. I do. For example, in a combination of an electrophotographic toner and a carrier, the toner corresponding to the sample powder has a particle size of about 1 to 30 μm, and the carrier powder corresponding to the friction partner powder has a particle size of about 30 to 500 μm. The mesh of the wire mesh 2 is selected to be smaller than the minimum diameter of the friction partner powder to be used.

Next, the operation of the apparatus of the present invention will be described.

First, the wire mesh 2 is attached between the wire mesh holder 3 and the Faraday cage 1. In this case, as shown in FIG. 1, the wire mesh 2 is inserted into the bottom 3c of the fitting portion 3a of the wire mesh holder 3, and the outer diameter of the lower end of the Faraday cage 1 is fitted into the fitting portion 3a. The wire mesh 2 used here is made of stainless steel and has a mesh size of 400 mesh. Thereafter, a mixed powder 5 (mixing weight ratio of 5:95) of a sample powder 4 having a particle size of 10 μm and a friction partner powder 6 having a particle size of 50 to 80 μm is placed from above the Faraday cage 1, and the wire mesh side is placed. Place it on the Teflon table 7 downward.

Next, a nozzle 10 for blowing a compressed gas to which a pressure hose 12 is connected is disposed above the mounting base 15, that is, at the upper end of the Faraday cage 1. As a result, the flow paths in the frictional charge measuring device are connected in a straight line from the gas inlet side A to the gas outlet side B.

In this state, a suction device (not shown) connected to the terminal of the suction system 11 is driven to start suction. As a result, gas is sucked into the conductive container from the vortex generation opening 13, and a vortex is generated on the lower surface of the wire mesh 2.
Gas is also sucked from the opening 16 of the upper nozzle mounting base 15 above the Faraday cage 1, and the mixed powder 5 is evenly distributed on the surface of the wire mesh by these airflows.

While maintaining the state in which the mixed powder 5 is uniformly distributed on the surface of the wire mesh 2 in this manner, the upper nozzle 10
Then, compressed gas is blown through the pressure hose 12 to remove the sample powder 4 through the wire mesh 2.

In the above operation, for example, first, gas is caused to flow from the opening 16 and the vortex generation opening 13 by the operation of the gas suction device, and the mixed powder is generated on the surface of the wire mesh by the vortex generated thereby. The body 5 is evenly distributed.
After operating the gas suction device in this way, 0.5 kg / cm 2 of compressed nitrogen gas is blown from the upper nozzle 10 through the pressure hose 12.

Thus, the mixed powder 5 is separated into the sample powder 4 and the friction partner powder 6, and the separated sample powder 4 is swirled on the surface of the wire mesh 2 and the suction airflow from the suction system 11 side. Thus, the wire is efficiently passed through the mesh of the wire mesh 2 and is removed to the suction system 11 side. As a result, the friction partner powder 6 remains on the upstream surface of the wire mesh 2.

At this time, the friction partner powder 6 forms a layer uniformly distributed on the surface of the wire mesh 2 by the eddy current generated on the surface of the wire mesh 2 and the gas flowing from above the Faraday cage 1 and forms the layer. By fixing, the friction partner powder 6 does not collide with the inner wall of the Faraday cage 1 or rub against the surface of the wire mesh 2. On the other hand, the blown sample powder 4 efficiently passes through the wire mesh 2 and is sucked downstream, so that the passed sample powder 4 (toner) does not adhere to the friction partner powder 6 again. .

The friction partner powder 6 remaining on the surface of the wire mesh 2 has an equal and opposite charge amount when the sample powder 4 is removed, and the charge amount Q in this case is the Faraday cage 1 To charge the capacitor 8 (capacitance C) connected to. Therefore, by measuring the voltage 9 at both ends, it becomes possible to obtain a measured value as Q = CV. FIG. 5 is a diagram in which the change over time of the charge amount is recorded. According to this diagram, it can be seen that the charge amount became saturated within one second after the start of the initial suction, and the sample powder 4 in the sample was completely removed. When the total measurement time was set to 1 second in the above mode and the weight of the Faraday cage 1 before and after the measurement was measured using an analytical balance, the weight loss after the measurement was reduced to the weight measured in the Faraday cage 1 Matched.

This indicates that the separation of the sample powder from the friction partner powder and the removal of the sample powder from the Faraday cage 1 were completed very quickly.

After the measurement, no toner adheres to the inner surface, the lower end, and the wire mesh 2 of the Faraday cage 1, and the friction partner powder 6 remaining in the Faraday cage 1 forms a uniform layer on the wire mesh 2. Formed and adhered.

The result is that the movement of the powder due to the blowing of the compressed gas and the suction from the gas discharge side is caused by the airflow flowing through the suction hole and the discharge hole and the vortex generation opening 13 sucked along the surface of the wire mesh 2. This indicates that the separated air is being separated and removed while keeping the friction partner powder substantially fixed in the vicinity of the wire mesh 2 by the synthetic airflow balanced with the compressed gas airflow.

The measurement of the triboelectric charge amount was completed in a short time of 1 second or less.

[0041]

According to the present invention, an opening through which gas can freely flow into the gas inflow side of the conductive container and a vortex generating means for generating a vortex in the surface of the wire mesh on the gas discharge side of the conductive container. At the start of the operation, the mixed powder of the sample powder and the friction partner powder can be uniformly distributed in advance on the surface of the wire mesh, and compressed from the upper nozzle while maintaining this uniform distribution state. By blowing the gas, the mixed powder is efficiently separated into the sample powder and the friction partner powder, so that a uniform layer of the friction partner powder can be formed and fixed on a wire mesh and the sample powder can be fixed. The body is effectively removed through the wire mesh and out of the Faraday cage.

As a result, the sample powder separated in the Faraday cage and the friction partner powder electrostatically attract each other, so that the powder can be almost completely separated without repeating bonding and separation. Since the opponent powder is not scattered at all, wear of the opponent powder is reduced, and loss of the opponent powder is reduced.

Further, the separated powder is very unlikely to reattach to the inner wall or lower end of the Faraday cage, so that the measurement accuracy of the charge amount is improved and the reproducibility of the measurement is significantly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a device for measuring the amount of triboelectric charge of a powder according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a wire mesh holder and a vortex generation opening.

FIG. 3 is a front view of a vortex generation opening.

FIG. 4 is a perspective view showing a state in which a wire mesh holder is incorporated in a Faraday cage.

FIG. 5 is a diagram showing a temporal change of a charge amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Faraday cage 2 ... Wire mesh 3 ... Wire mesh holder 4 ... Sample powder 5 ... Mixed powder 6 ... Friction partner powder 7 ... Teflon stand 8 ... Condenser 9 ... Voltage 10 ... Top nozzle 11 ... Suction system 12 ... Pressure hose 13 ... Eddy current generating opening 14: Air flow guide 15: Mounting base 16: Opening

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01R 29/24 G01N 27/60

Claims (2)

(57) [Claims] 1. A mixed powder of a triboelectrically charged sample powder and a friction partner powder is placed in a conductive container having a wire mesh stretched thereon, and the mixed powder is mixed with the sample powder by an air current. At the same time as separating into the friction partner powder, only the sample powder having a small particle diameter of the mixed powder is discharged through the wire mesh, and the charge amount of the large-diameter friction partner powder remaining in the wire mesh is measured. In an apparatus for measuring the amount of triboelectric charge of a powder, a gas outlet for blowing compressed gas at an upper end and a gas inlet for introducing gas around the gas outlet are provided , and a gas suction for sucking the compressed gas at a lower end. A cylindrical conductive container having an open mouth; a sample powder and a friction partner which are stretched between the gas inlet and the gas suction port of the conductive container and accommodated in the conductive container; samples powder is selected passage with suction and blowing of the compressed gas out of the powder Network and an opening for flowing gas is formed in the horizontal direction on the lower surface outer peripheral portion of the gold network, a vortex generating means for generating a vortex flow of the gas from the opening and flows toward the wire mesh surface, the conductive container A gas suction means for sucking compressed gas ejected from a blowing port at an upper end of the wire mesh at a lower portion of the wire mesh; and a charge amount measuring means for measuring a charge amount of a friction partner powder remaining in the conductive container. An apparatus for measuring the amount of triboelectric charge of powder. 2. A gas outlet for blowing compressed gas into the upper end.
And a gas inlet for introducing gas around the gas outlet.
A gas suction port for sucking the compressed gas at the lower end.
And a wire mesh between the gas inlet and the gas suction port.
The conductive material is placed at the bottom of a cylindrical conductive container
Vortex flow with an opening for gas flow in the horizontal direction of the container
A raw means can be arranged to pass through the wire mesh triboelectrically charged in the conductive container.
Sample powder with small particle size and friction partner with larger particle size than the sample powder
Containing the mixed powder with the powder, and gas suction of the conductive container.
Suction from the gas inlet and vortex of the conductive container
The lower part of the wire mesh by the gas flow flowing from the opening of the raw means
To form a swirl of gas on the wire mesh surface
Distribute evenly, and then remove the gas from the conductive container
By blowing compressed gas from the
Pass only the sample powder through the wire mesh while separating
And then discharged, and then the friction partner powder remaining in the wire mesh
A method for measuring the triboelectric charge of a powder for measuring the charge of a powder.