JP2006029897A - Blowoff measurement device and blowoff measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blowoff measurement device equipped with a mesh part with a fine aperture capable of surely measuring the charge quantity even for a developer using a carrier of small particle diameter and moreover the carrier is free from clogging at the aperture of the mesh. <P>SOLUTION: The blowoff measurement device is characterized in that the developer is containing a charged toner and an inversely charged carrier, a container is storing the developer and a mesh part provided with the aperture capable of passing though only the toner as charged state from inside of the container to outside by injection of gas into the container for obtaining the charge quantity of the evicted toner after injection of the gas by detecting the charge quantity of the carrier remaining in the container. The mesh part at least a part of it is made of woven plastic fine fibers, and together with the plastic mesh at least a sheet of metal mesh having larger aperture than the resin mesh is overlapped. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a device that uses a blow-off measuring device as a toner evaluation device in, for example, a copying machine, a facsimile machine, a printer, and the like.

  Conventionally, there are many cases where a two-component developer composed of a toner and a carrier is used as a developer in an electrophotographic recording apparatus. When this two-component developer is used, the charge amount of the toner greatly affects the image quality. For this reason, in order to obtain good image quality, an evaluation means for optimizing the charge amount of the toner is required, and for example, an evaluation means called blow-off has been used as this evaluation means. In this evaluation means, after a developer in which toner is electrostatically adhered to a carrier is placed in a metal container with a mesh (mesh) having a diameter that allows only toner to pass through. The toner and the carrier are agitated by blowing a gas such as dry air, and only the toner is blown out of the metal container. As a result, since the charge having the same charge amount as that of the toner and having the opposite polarity can be detected as the entire container, the charge amount of the toner is detected using this evaluation means.

The outline of the conventional apparatus (refer patent document 1) which performs a blow-off measurement below is demonstrated.
The two-component developer to be evaluated by the blow-off evaluation apparatus shown in FIG. 1 is charged so that the toner (11) and the carrier (12) having a diameter larger than that of the toner (11) have charges of opposite polarity due to frictional charging. The plurality of toners (11) are adhered around the carrier (12) by electrostatic force. In this state, the total charge as a whole is zero.
Further, a part of the metal container (13) is constituted by a mesh portion (14), and the opening diameter of the mesh portion (14) is larger than the diameter of the toner (11), and is larger than the diameter of the carrier (12). Is also getting smaller. Then, the developer described above is accommodated in the container (13), and the gas (16) is blown from the outside with the nozzle (15) to physically stir the toner (11) and the carrier (12). To separate. Furthermore, only the separated toner (11) smaller than the opening of the mesh (14) passes through the opening of the mesh (14) and is blown off to the outside. At this time, since the toner (11) is blown off while being charged, a charge having a polarity opposite to that of the toner (11) is detected in the entire container (13). An evaluation method based on blow-off evaluation is to evaluate the charge of the toner (11) from the charge amount thus obtained.

However, in recent years, the carrier particle size of the two-component developer tends to be small, that is, the difference between the toner and the carrier diameter tends to be small, and accordingly, when performing evaluation by blow-off, the function of separating the toner and the carrier. The wire mesh (mesh) having a diameter is required to be finer, and a highly accurate one is required. However, conventional meshes are generally made by knitting SUS fine wires, and the opening diameters of meshes made in this way are limited by the thickness of the wires, and are already limited for industrial use. Was greeted.
The developer container containing the developer is closed with an aluminum alloy or stainless steel mesh, and the toner is sucked and removed, whereby a charge amount difference and a weight difference are generated in the developer container, and the charge amount is similarly obtained. The technology described in Patent Document 2 including the above, preferably a cylindrical housing constituting the side wall of the cell, a separating stainless steel mesh provided at the lower end of the housing, and one or more provided at the upper end of the housing The technology described in Patent Document 2, which uses a cell made of a metal material that is electrically conductive and non-magnetic as a whole, has a top lid 43 having a vent hole, and a metal mesh and upper center in the lower part Fill the unit cell with a small-diameter ventilation hole with a two-component developer and suck it through the mesh so And an upward flow along the wall of the unit cell and an air flow from the lower side of the mesh toward the lower surface of the mesh, and the toner separated through the mesh is discharged out of the unit cell. The toner concentration and the average charge amount in a two-component developer are calculated by calculating the toner concentration from the weight reduction or discharged toner amount of the developer in the unit cell and calculating the charge amount from the charge amount of the unit cell The techniques described in Patent Documents 3, 4, 5, 6, and 7 relating to measurement are also the same.

As a method for solving the above problem, for example, a blow-off measuring device (see Patent Document 1) in which a mesh formed by irradiating a resin material with a laser is adopted as a mesh portion has been proposed. The mesh formed by this method has fine openings, and it is possible to separate the toner and the carrier even for a developer using a carrier having a small particle diameter, and blow-off evaluation can be performed. However, the shape of the mesh opening becomes nearly circular due to the diffusion of the irradiation laser light at the time of mesh creation. In particular, this tendency becomes more prominent as the fine opening is formed.
In general, the projected shape of the carrier is close to a circle, but if the shape of the mesh opening is close to a circle, the carrier having a projected shape close to a circle and having a particle size slightly larger than the mesh opening diameter will adhere to the mesh opening without gaps. The mesh opening will be clogged. If the mesh opening is sealed in this way, not only the carrier and the toner cannot be separated, but also the blown gas loses the escape place, and in the worst case, the mesh is damaged. In addition, when the carrier comes into close contact with the mesh opening in this manner, it becomes very difficult to remove the carrier from the mesh. Therefore, this method is not suitable for cleaning and reusing the mesh, and the life of the mesh is short.

  Unlike the above-described method of forming a metal mesh, a method of forming a mesh by electrodeposition is also considered. However, according to this electrodeposition method, since the growth of the plating is isotropic, it is necessary to increase the interval between the openings of the mesh, and it becomes difficult to obtain a sufficient opening ratio. If the opening ratio is not sufficient, the inside of the container is not sufficiently stirred at the time of blowing, and further, the force for blowing off the toner is insufficient, resulting in a problem that it is difficult to obtain an accurate result. Moreover, the manufacturing process is long and complicated, such as photolithography.

JP 9-218533 A JP 2001-124810 A JP 2000-194187 A Japanese Patent Laid-Open No. 10-26883 JP-A-9-101680 JP-A-10-26877 Japanese Patent No. 3269949

  The present invention was made to solve the above problems, and even with a developer using a carrier having a small particle diameter, the charge amount can be reliably measured, and It is an object of the present invention to provide a blow-off measuring device provided with a mesh portion having a fine opening in which the carrier does not clog the mesh opening.

The present inventors have intensively studied to solve the above problems. The present invention has been made based on this.
That is, the above-described problem is solved by (1) “a developer containing a charged toner and a carrier charged with a polarity opposite to that of the toner”, a container containing the developer, and blowing a gas into the container. A mesh portion having an opening that allows only the toner to pass from the inside of the container to the outside of the container to be removed in a charged state, and detecting the amount of charge of the carrier remaining in the container after the gas is blown In the blow-off measuring device for determining the charge amount of the removed toner, at least one part of the mesh part is composed of at least one resin mesh knitted with a fine resin wire, and the resin mesh is composed of metal. Blow-off measurement characterized in that at least one metal mesh having a larger opening than the resin mesh is provided in an overlapping manner. (2) “Blow-off measuring device according to item (1) above, wherein the metal mesh is provided outside the resin mesh with respect to the container”, (3) “The metal The blow-off measuring device according to item (1), characterized in that a mesh is provided on both surfaces of the resin mesh. (4) “The mesh portion is provided in all openings of the container. The blow-off measuring device according to any one of items (1) to (3) ”, (5)“ The conductive film is formed on the surface of the resin mesh. The blow-off measuring device according to any one of items 1) to (4) ”, (6)“ the resin mesh is made of nylon, ”the items (1) to (5), The blow-off measuring device according to any one of ", ( ) “The blow-off measuring device according to any one of (1) to (5) above, wherein the resin mesh is made of polyester”, (8) “the gas blown into the container It is solved by the blow-off measuring device according to any one of (1) to (7) above, characterized in that it has means for sucking air.
In addition, the above problem is solved by (9) “Charging amount measuring method using the blow-off measuring device according to any one of (1) to (8)” of the present invention. The

  By using the blow-off measuring device of the present invention, it becomes possible to reliably separate the toner and the carrier even in a developer using a carrier having a small particle diameter, and the charge amount is more accurate than the conventional blow-off measuring device. Measurements can be made.

  The present inventors have intensively studied to solve the problems of the present invention, and the mesh portion of the blow-off measuring device has a mesh opening larger than that of the resin mesh composed of a resin mesh knitted with resin fine wires and metal. We have devised a new technology concept that is very effective in solving the above-mentioned problems.

  The mesh part of the blow-off measuring device has a role of separating the toner and the carrier in the developer and forming an electric shield to prevent leakage of electric lines of force. Therefore, it is necessary to satisfy the conditions of (1) having an opening diameter that allows the toner to pass and does not allow the carrier to pass, (2) has a strength that does not break even when gas is blown, and (3) has conductivity. is there. A mesh produced by knitting SUS fine wires generally satisfies these conditions, and is generally used in a mesh portion of a blow-off measuring device.

  In recent years, there is a tendency to reduce the carrier particle size of the two-component developer due to market demand for higher image quality of electrophotography. Therefore, in order to satisfy the condition that the toner is allowed to pass and the carrier is not allowed to pass, a metal mesh having a finer opening diameter and a high accuracy is required. However, in the metal mesh, the refinement of the opening diameter has reached an industrial limit due to the limitation of the thickness of the line, and the further refinement of the opening diameter cannot be easily realized.

  A resin mesh knitted with a fine resin wire can form a finer mesh opening than a metal mesh knitted with a fine metal wire, and is widely marketed even from a mesh having an opening diameter of 1 μm. However, since the resin mesh is weaker than the metal mesh, it is easily damaged, and since it is insulative, an electrical shield cannot be formed, and accurate measurement cannot be performed.

  Therefore, as shown in FIG. 2, the mesh portion of the measurement container is configured to overlap the resin mesh (21) and the metal mesh (22), so that among the mesh portion conditions (1) to (3) above, (1 ) Plays the role of the resin mesh, and the metal mesh is used as a reinforcement of the resin mesh to prevent the force from concentrating on the end of the resin mesh, so that the condition (2) is satisfied and the metal mesh is used. Thus, the present inventors have found that it is possible to form an electrical shield and satisfy the condition (3).

  One resin mesh and one metal mesh in the mesh portion play a sufficient role as the mesh portion, but two or more of them may be used in order to further increase the strength of the mesh portion. Two or more resin meshes may be used to prevent the carrier from jumping out of the container.

The resin mesh in the present invention is preferably a knitted fine wire made of resin. If the mesh is a fine knitted mesh, the shape of the mesh opening will be square even if it is a fine opening, and even if the carrier is clogged with the mesh opening, the projected shape of the carrier will be almost circular, so it will not be completely sealed . Therefore, the blown gas can always be discharged without losing the escape place, and as a result, the stress applied to the mesh portion can be reduced. Further, since the clogged carrier and the mesh opening are not in close contact with each other, the carrier can be easily washed away by washing the mesh. Furthermore, the fact that the fine wire knitted as a mesh has a slight degree of freedom in the direction perpendicular to the fine wire is also one of the factors for the ease of washing off the carrier.
In the present invention, the mesh size necessary for separating the toner and the carrier differs depending on the sizes of the toner and the carrier, so it is difficult to determine and describe a particularly preferable size. However, since the price of SUS mesh suddenly increases when the mesh size is 20 μm or less, when a mesh with a mesh size of 20 μm or less is required to separate the carrier and the toner, a resin mesh with a mesh size of 20 μm or less is used. If used, it is true that it is effective in terms of cost.

  The metal mesh (22) is preferably disposed outside the resin mesh (21) as seen from the container side as shown in FIG. If the metal mesh and the resin mesh are completely bonded, the metal mesh may be arranged inside the resin mesh when viewed from the container side, but it is better to arrange the metal mesh in the direction in which the sprayed gas is discharged from the container From the viewpoint of physical strength, it is preferable. Also, from an electrical viewpoint, the shield is preferably formed on the outermost surface of the container. Therefore, it is preferable to dispose the metal mesh outside the resin mesh when viewed from the container side.

  Moreover, it is preferable to provide not only the outer side of the resin mesh (21) but also the inner side when the metal mesh (22) is viewed from the container side as shown in FIG. Measurement is possible by simply providing the metal mesh on the outside of the resin mesh when viewed from the container side, but by providing the metal mesh on the inside, it is possible to prevent the developer from causing frictional charging with the resin mesh to some extent. . There is also an advantage that the strength of the mesh portion can be further strengthened.

  It is preferable that the mesh part is provided in all the openings of the container. Specifically, it is preferable to be provided not only at the gas outlet in the container but also at the spray outlet. The developer is separated from the toner and carrier at the mesh part of the gas discharge port by the flow of the blown gas, but part of the blown gas may flow backward and the gas may be discharged from the spray port. In this case, it is preferable that the toner and the carrier can be separated even at the gas blowing port. Therefore, by providing a mesh portion at the gas discharge port, it is possible to separate the toner and the carrier even with respect to the developer on the backflowed gas, and more accurate measurement can be performed.

  The resin mesh may be used as it is, but by forming a conductive film on the surface of the resin mesh, frictional charging between the developer and the resin mesh can be prevented, and an electrical shield can also be formed. It is preferable because it is possible.

  The conductive film can be formed by a film formation process such as sputtering, vacuum evaporation, or CVD. In particular, in the film formation by sputtering, the metal particles jump out in a random direction from the target, so that it is possible to reach the inside of the mesh opening, and as a result, the inside of the opening can be formed by metal. As described above, the film formation method by sputtering is a preferable method because the conductive treatment can be more completely performed as compared with other film formation methods.

  The material of the resin mesh is not particularly limited, and a known resin such as a nylon resin, a polyester resin, an acrylic resin, or a fluorine resin can be used as long as the mesh can be created. Of these, nylon resin is preferred because of its high durability and chemical resistance, and polyester resin is preferred because of its high durability and weather resistance. Examples of commercially available products include NITEX (nylon mesh) and PETEX (polyester mesh) manufactured by SEFAR (Switzerland).

  As shown in FIG. 4, the blow-off measuring device of the present invention may be provided with means for sucking the gas blown to the container, as shown in, for example, Japanese Patent Application Laid-Open No. 8-313487. In the present invention, a resin mesh having a small opening diameter is used to separate the carrier and the toner having a small particle diameter. However, since the opening diameter of the mesh is small, the inflow of gas into the container, The degree of gas outflow is low. Therefore, by providing means for sucking the gas blown to the container, it is possible to promote the flow of the gas and to smoothly separate the toner and the carrier.

  The gas blown to the container is not particularly defined, but it is preferable to use air or nitrogen that is as dry as possible in order not to change the charged state of the developer to be measured. When a gas containing a large amount of moisture is used, the charge amount of the developer decreases, and there is a possibility that the measurement result of the developer in the measurement target state cannot be obtained accurately.

  Actually, for a developer prepared using a toner having a volume average particle diameter of 8 μm and a carrier having a volume average particle diameter of 30 μm, a blow-off measuring device configured as shown in FIG. 1 using a SUS mesh having an opening of 20 μm in the mesh portion is used. When the charge amount was measured using the developer, the mass of the developer after blowing was less than the carrier mass that should have been present in the developer. This means that the carrier having a particle size distribution has been discharged out of the container without being separated from the toner at the mesh portion. As described above, if the amount of the carrier discharged from the container without being separated from the toner is large, an error in measurement becomes large and correct charge amount measurement cannot be performed.

Therefore, in the configuration shown in FIG. 4, when the same charge amount measurement was performed using a nylon mesh with an opening diameter of 15 μm for the resin mesh and a SUS mesh with an opening of 90 μm for the metal mesh, the developer mass after blowing was The amount was almost the same as the carrier mass that should have been present in the developer. From this, it can be said that the blow-off measuring device of the present invention can measure the toner charge amount more accurately than the conventional blow-off measuring device.
In addition, when the resin mesh after use was subjected to ultrasonic cleaning in an organic solvent for 10 minutes and dried, and the mesh opening was observed with an optical microscope, very few carriers remained in the resin mesh opening. I was able to confirm.

It is a figure which shows the conventional blow-off measuring apparatus. It is a figure which shows an example of the blow-off measuring apparatus of this invention. It is a figure which shows the other example of the blow-off measuring apparatus of this invention. It is a figure which shows the other example of the blow-off measuring apparatus of this invention.

Explanation of symbols

11 Toner 12 Carrier 13 Container 14 Mesh portion 15 Gas spray nozzle 16 Blow gas 21 Resin mesh 22 Metal mesh

Claims (9)

A developer containing a charged toner and a carrier charged to a polarity opposite to that of the toner, a container containing the developer, and blowing only gas into the container so that only the toner remains charged from the container to the outside of the container. A blow-off measuring device for obtaining a charge amount of toner removed by detecting a charge amount of a carrier remaining in the container after the gas is sprayed. In addition, at least one part of the mesh part is constituted by at least one resin mesh knitted fine resin wire, and a metal mesh having a larger opening than the resin mesh made of metal is formed on the resin mesh. A blow-off measuring device, wherein at least one sheet is provided in an overlapping manner. The blow-off measuring device according to claim 1, wherein the metal mesh is provided outside the resin mesh with respect to the container. The blow-off measuring device according to claim 1, wherein the metal mesh is provided on both surfaces of the resin mesh. The blow-off measuring device according to any one of claims 1 to 3, wherein the mesh portion is provided in all openings of the container. The blow-off measuring device according to any one of claims 1 to 4, wherein a conductive film is formed on a surface of the resin mesh. The blow-off measuring device according to claim 1, wherein the resin mesh is made of nylon. The blow-off measuring device according to claim 1, wherein the resin mesh is made of polyester. The blow-off measuring device according to claim 1, further comprising means for sucking the gas blown into the container. A charge amount measuring method using the blow-off measuring device according to claim 1.

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