JP2007127862A - Developing device, and image forming apparatus and process cartridge using the developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of always stably conveying toner without scattering toner and soiling the base of an image, and to provide an image forming apparatus, developing method, image forming method and process cartridge which use the developing device. <P>SOLUTION: A developer carrier 43 for conveying developer while forming a magnetic brush and a toner conveying member 40 for conveying toner supplied from the supply member are disposed opposite to each other via a nip area (A2). The particular area of an electrode preset on a conveying member located within the nip area, serving as a boundary, splits the direction of a toner conveyance electric field. One of the directions is assigned to convey toner toward a developing area (A1), and the other is assigned to convey toner opposite the developing area (A1). Thus configured developing device is mounted in the process cartridge and image forming apparatus. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device including a developer supply member that transports a developer and a toner transport member that transports toner supplied from the developer supply member, and in particular, transports toner from the developer supply member in a nip region. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device configured to suitably transport toner supplied to a member to a developing region without deposition or sticking by a transport electric field, an image forming apparatus using the same, a process cartridge, a developing method, and an image forming method. .

  As an image forming apparatus such as a copying machine, a printer, or a facsimile machine, an electrophotographic process is used to form a latent image on a latent image carrier, and toner (hereinafter sometimes referred to as “powder”) is formed on the latent image. To form a visible image as a toner image, and the toner image is transferred to a recording medium or transferred to an intermediate transfer member and then transferred to a recording medium to form an image.

  In such an image forming apparatus, as a developing device for developing a latent image, conventionally, the toner stirred in the developing device is carried on the surface of the developing roller as a developer carrying member, and the developing roller is rotated. The latent image carrier is transported to a position facing the surface of the latent image carrier, and the latent image on the latent image carrier is developed. After the development, the toner that has not been transferred to the latent image carrier is collected in the developing device by the rotation of the developing roller. In addition, there is a known toner that is newly stirred and charged and then carried again on the developing roller and conveyed.

  For example, a method has been proposed in which a toner conveying device is composed of a base member, a linear electrode array, and an AC multiphase power supply, and toner charged by a traveling electrostatic wave pattern is supplied to the image forming surface. The toner conveying device includes a rotatable brush and is configured to supply toner from a toner supply source to a base member (see, for example, Patent Document 1).

  Further, a method has been proposed in which the developer precharged by the precharging means is supplied to a developer carrying body provided with a carrying electric field generating means, and the supplied developer is carried by the developer carrying body. As one of the preliminary charging means in this case, charging is performed by using a method of rubbing the developer between the preliminary charging roller and the developer carrying body. As another preliminary charging means, a method is used in which toner and carrier are used as developers, and charging is performed by frictional contact with stirring blades. In this case, the developer is held on the surface of the sleeve roller by using a sleeve roller having a magnet roller built in, and is supplied to the developer carrying body in the state of a magnetic brush (for example, Patent Document 2). reference.).

In both Patent Document 1 and Patent Document 2, the toner is transported to a position facing the latent image carrier, and is vibrated, floated, smoked, and is sucked from the latent image carrier by the suction force generated from the transport surface. The toner is separated and adhered to the surface of the latent image carrier.
However, Patent Document 1 merely supplies only the charged toner from the two-component magnetic brush to the transport electrode. With such a technique, if the amount of toner supply increases, the toner may accumulate and become unable to be transported. There is sex. On the other hand, the method of Patent Document 2 in which the precharged toner is simply supplied to the conveying member and conveyed by the electric field curtain also causes a problem that the toner sticks to the conveying member when the toner is excessively supplied as described above.
Therefore, in the above technique, only the magnetic brush roller that has been conventionally used is applied, and the proper conditions for toner conveyance are not taken into consideration, so that it becomes unstable over time and stable toner conveyance by the toner conveyance member There is a problem that cannot be performed.

On the other hand, the applicant uses a phenomenon including horizontal movement (conveyance) and vertical movement (hopping) of the powder due to electrostatic force, and the surface of the electrostatic conveyance member is moved by the phase-shift electric field. An apparatus using a developing method utilizing a phenomenon of jumping with a component in the traveling direction has been proposed.
That is, the developing device includes a conveying member that is disposed to face the latent image carrier and has a plurality of electrodes for generating a traveling wave electric field that moves the powder. Is applied to the image portion of the latent image toward the latent image carrier, and to the non-image portion, an n-phase potential is applied to form an electric field in a direction in which the powder is directed to the opposite side of the latent image carrier. The developer is supplied to the conveying member so that charged toner is directly supplied to the conveying member on the flat plate (see, for example, Patent Document 3).
Further, the applicant of the present invention provides a high-quality toner by defining a toner charge quantity distribution in a developing device that includes a magnetic brush row and a developing roller that conveys toner supplied from the magnetic brush row to a photoreceptor. A technique for forming an image has been proposed (see, for example, Patent Document 4).

According to the technique disclosed in Patent Document 3 in which toner is transported to the vicinity of the image carrier by the transport member having the transport electrode, the toner is stably supplied to the transport member that transports the toner by the phase-shift electric field. be able to. Further, according to the method of Patent Document 4, a toner image free from background stains and insufficient image density is formed.
However, none of the above developing devices has a detailed definition of the supply member, and if a large amount of toner is supplied, there is a possibility that the toner will stay on the conveyance member and the predetermined toner conveyance cannot be performed. It is desirable to allow the toner to be transported to the development area.

JP 60-257461 A Japanese Patent Publication No. 3-21967 JP 2004-198675 A JP 2001-272857 A

As described in the prior art, as a configuration of a developing device that develops by attaching toner to a latent image on a latent image carrier, a magnetic brush (magnetic brush) is formed by a supply member using a two-component developer. 2. Description of the Related Art There has been known a technique in which toner is charged in advance and the charged toner is supplied from a supply member to a conveyance member (conveyance substrate).
When supplying the charged toner from the supply member to the conveyance member, the toner is moved from the supply member to the electrode of the conveyance member mainly by the force of the electric field, but the supply amount at this time is excessive or the timing is shifted. In some cases, the toner may stay on the transport electrode or the amount of developer transported may be extremely reduced. In particular, the amount of toner supplied from the supply member to the transport substrate increases, and when the toner is stacked on the transport substrate to form a multilayer, the transport electric field of the transport substrate does not act on the toner or the toner aggregates and forms a transport substrate. There is a possibility that the toner adheres (sticks) and, in the worst case, the toner is not conveyed.

That is, the present invention has been made in view of the above problems, and a developer supply member that forms a magnetic brush and conveys the developer, and toner that is supplied from the developer supply member is conveyed to the development region. A developing device including a toner conveying member;
The developer is transported in a high density state by the developer supply member, and a large amount of toner is always stably supplied to the toner transport member, and the supplied toner is not deposited or stuck by the toner transport member over time. An object of the present invention is to provide a developing device that can stably convey and is free from toner scattering and image smearing, as well as an image forming apparatus, a process cartridge, a developing method, and image forming using the developing device. It aims to provide a method.
At the same time, the developing device of the present invention uses an EH (Electrostatic Transport & Hopping) phenomenon to enable low voltage driving and to achieve high developing efficiency.

  Here, the EH phenomenon refers to a phenomenon in which the powder itself is given a phase-shifting electric field energy, the energy is converted into mechanical energy, and the powder itself dynamically changes. This EH phenomenon is a phenomenon including horizontal movement (conveyance) and vertical movement (hopping) of the powder due to electrostatic force, and the surface of the electrostatic conveyance member is moved in the direction of travel by the phase-shift electric field. This is a phenomenon of jumping with components, and a developing system using this EH phenomenon is called EH development.

  In this specification, when the behavior of the powder on the transport member in the EH phenomenon is distinguished and expressed, the movement in the horizontal direction of the substrate is “transport”, “transport speed”, “transport direction”, “transport”. The expression “distance” is used, and for the flight (movement) in the vertical direction of the substrate, the expressions “hopping”, “hopping speed”, “hopping direction”, and “hopping height (distance)” are used. “Transport and hopping” above is collectively referred to as “transfer”. Note that “transport” included in the terms of the transport member and the transport substrate is synonymous with “transfer”.

  As a result of intensive studies, the inventors of the present invention have defined the electric field condition of the toner conveying member or the arrangement condition of the toner conveying member in the nip region for supplying toner from the developer supply member of the developing device to the toner conveying member. The inventors have found that the above problems can be solved and have reached the present invention. Hereinafter, the present invention will be specifically described.

That is, according to the present invention, the developer is held on the surface, and the developer supply member that transports the developer and the toner supplied from the developer supply member to the development area (A1) facing the latent image carrier. A developing device that includes a toner conveying member that conveys the toner and attaches the toner to the latent image on the latent image carrier in A1, and develops the toner.
The developer supply member and the toner conveying member are arranged to face each other via a nip region (A2) where the developer supply member supplies toner,
The developer supply member is connected to a power supply (B1) for forming a toner supply electric field,
The toner transport member includes a plurality of electrodes and is connected to a power source (B2) that forms a transport electric field on the electrodes.
When transporting the toner supplied from the developer supply member to the toner transport member by applying a bias of the power supply (B1),
By applying a bias of the power source (B2), the direction of the toner electric field is divided at a predetermined position of the electrode located in the nip area (A2), and one of the toner is directed toward the development area (A1). The other is a developing device characterized in that it is configured to go in the opposite direction to A1. (Claim 1)

  With the above configuration, a large amount of toner is stably supplied from the developer supply member in a high density state to the toner transport member, and the toner transport electric field direction is divided in the nip region (A2). The toner conveyance amount is properly defined, and toner conveyance can be performed efficiently and stably without causing toner accumulation or sticking. Further, low-voltage driving is possible, and high-quality development can be performed with high development efficiency without toner scattering and image smearing.

  In the developing device (claim 1), the toner conveying member is a member having any one of a cylindrical shape, a belt shape, and a substrate shape.

  The developing device can be used in any shape of a cylindrical, belt-shaped or substrate-shaped conveying member, and can efficiently and stably convey toner without causing toner accumulation or sticking. Therefore, it is possible to flexibly cope with the configuration of the mounted image forming apparatus.

  According to the present invention, in the developing device (Claim 1), the toner transport direction to the development area (A1) by the toner transport member is opposite to the developer transport direction by the developer supply member. And

  By reversing the toner transport direction and the developer supply direction, for example, the toner dissociated from the carrier of the two-component developer is supplied to the toner transport member again without being captured by the carrier or developer carrier. In addition, the toner can be transported in a transport electric field stably and efficiently without sticking.

  According to the present invention, in the developing device (Claim 1), the boundary at a predetermined position of the electrode located in the nip region (A2) that divides the direction of the electric field of toner conveyance can be changed by applying a bias of the power source (B2). It was made to let it be made to do.

  By making the boundary at a predetermined position of the electrode variable, even if toner sticking occurs over time, it is possible to change and set the boundary that divides the direction of electric field of toner to avoid the sticking part As a result, the toner can always be stably conveyed, and uniform and high-quality development can be performed.

  According to the present invention, in the developing device (Claim 1), the developer is a two-component developer composed of a magnetic carrier and a nonmagnetic toner, and the toner adheres an additive to the surface of the toner base. The coverage of the additive with respect to the surface area of the toner base is 50% or more.

The two-component developer has better toner charging stability than the one-component developer. By using the two-component developer, a magnetic brush is suitably formed on the surface of the developer carrying member, and the toner is hopped well. And can be transported.
By defining the coverage ratio of the additive to the surface area of the toner base (resin as a main component), the toner conveying member is more efficiently and stable without causing toner accumulation or sticking. The toner can be conveyed.

Further, according to the present invention, a developer supply member that holds a developer on the surface and conveys the developer, and a toner supplied from the developer supply member to a development area (A1) that faces the latent image carrier. A developing device that includes a toner conveying member that conveys the toner and attaches the toner to the latent image on the latent image carrier in A1, and develops the toner.
The developer supply member and the toner conveying member are disposed to face each other via a nip region (A2) where the developer supplying member supplies toner, and one end of the toner conveying member is in the nip region (A2). Arranged,
The developer supply member is connected to a power supply (B1) for forming a toner supply electric field,
The toner transport member includes a plurality of electrodes and is connected to a power source (B2) that forms a transport electric field on the electrodes.
When transporting the toner supplied from the developer supply member to the toner transport member by applying a bias of the power supply (B1),
By applying a bias of the power source (B2), a toner conveying electric field direction is formed using one end of the toner conveying member disposed in the nip area (A2) as a conveying start point, and the toner moves toward the developing area (A1). The developing device is configured as described above. (Claim 6)

  With the above configuration, a large amount of toner is stably supplied from the developer supply member to the toner transport member, and one end of the toner transport member disposed to face the developer supply member is connected to the nip region (A2). ) And forming the toner electric field direction with the end thereof as the conveyance start point, the toner conveyance amount is properly defined, and the toner can be efficiently accumulated without causing toner accumulation or sticking. The toner can be stably conveyed. Further, low-voltage driving is possible, and high-quality development can be performed with high development efficiency without toner scattering and image smearing.

  In the developing device (claim 6), the toner conveying member is a member having any one of a cylindrical shape, a belt shape, and a substrate shape.

  As described in the developing device (Claim 1), any cylindrical, belt-like or substrate-like conveying member shape can be used, and toner can be stably conveyed. It is possible to respond flexibly to the configuration of

  In the developing device (claim 6), the toner transport direction by the toner transport member and the developer transport direction by the developer supply member are opposite to each other.

  As described in the developing device (Claim 1), for example, the toner dissociated from the carrier of the two-component developer is supplied again to the toner conveying member without being captured by the carrier or the developer carrying member, and is stuck. Therefore, the toner can be transported on the transport electric field more efficiently and stably.

  According to the present invention, in the developing device (Claim 6), the developer is a two-component developer composed of a magnetic carrier and a nonmagnetic toner, and the toner adheres an additive to the surface of the toner base. The coverage of the additive with respect to the surface area of the toner base is 50% or more.

As described in the developing device (Claim 1), by using a two-component developer, a magnetic brush is suitably formed on the surface of the developer carrying member, and the toner is conveyed well.
By defining the coverage of the additive, toner can be transported more efficiently and stably without causing toner accumulation or sticking to the toner transport member.

According to another aspect of the present invention, there is provided an image forming apparatus comprising the developing device as described above.
It is related to.

  According to the image forming apparatus, since any one of the developing devices described above is provided, there is no scattering of toner or background contamination, stable supply of toner over time can be achieved, and image quality can be improved. In addition, the apparatus can be reduced in size and cost.

  The present invention also relates to a process cartridge characterized by integrally holding at least one of a latent image carrier, a charging unit, and a cleaning unit in an electrophotographic process, and the developing device described above. It is.

  According to the process cartridge having the above-described configuration, low voltage driving is possible, high-quality development can be performed with high development efficiency, the apparatus can be downsized and maintenance can be improved, and it is always stable by replacing as appropriate. Development can be performed.

  The present invention also relates to an image forming apparatus including the process cartridge described above.

  According to the image forming apparatus provided with the process cartridge, a stable and high-quality image can always be formed by appropriately replacing the cartridge. In addition, the maintainability is good, and the apparatus can be reduced in size and cost.

  According to another aspect of the present invention, there is provided a developing method characterized in that the developing device according to any one of the above includes developing toner by attaching toner to the latent image on the latent image carrier.

  According to the above developing method, it is possible to stably carry the toner without causing toner accumulation or sticking to the toner carrying member over time, and without developing toner scattering and image smearing. Quality is improved.

  The present invention also relates to an image forming method using the developing method described above.

  According to the image forming method, low voltage driving is possible, high quality development can be performed with high development efficiency, and a high quality image can always be stably formed.

The developing device according to the present invention provides a developing device with high development quality capable of stably supplying toner even over time. Further, since development can be performed at a low voltage, durability of the latent image carrier is improved and environmental problems can be avoided.
According to the image forming apparatus of the present invention, the image quality can be improved, and the size and cost of the apparatus can be reduced.
According to the process cartridge of the present invention, it is possible to improve maintainability and downsize the apparatus.
According to the image forming apparatus including the process cartridge according to the present invention, the image quality can be improved. If a plurality of process cartridges are provided, a full-color image forming apparatus can be configured.
According to the developing method of the present invention, toner can be supplied stably and high quality development can be performed with high development efficiency.
According to the image forming method of the present invention, a high-quality image can be formed by high-quality development by low voltage driving, toner scattering suppression, and the like.

As described above, the developing device according to the present invention has a developer holding member that holds the developer on the surface and transports the developer, and the toner supplied from the developer supplying member that faces the latent image carrier. A developing device that includes a toner conveying member that conveys the toner to a region (A1), and develops the toner by attaching the toner to the latent image on the latent image carrier in A1;
The developer supply member and the toner conveying member are arranged to face each other via a nip region (A2) where the developer supply member supplies toner,
The developer supply member is connected to a power supply (B1) for forming a toner supply electric field,
The toner transport member includes a plurality of electrodes and is connected to a power source (B2) that forms a transport electric field on the electrodes.
When transporting the toner supplied from the developer supply member to the toner transport member by applying a bias of the power supply (B1),
By applying a bias of the power source (B2), the direction of the toner electric field is divided at a predetermined position of the electrode located in the nip area (A2), and one of the toner is directed toward the development area (A1). The other is configured to be opposite to A1.

The developing device according to the present invention includes a developer supply member that holds a developer on the surface and conveys the developer, and a toner that is supplied from the developer supply member and a development region ( A developing device for developing the toner by attaching the toner to the latent image on the latent image carrier in A1;
The developer supply member and the toner conveying member are disposed to face each other via a nip region (A2) where the developer supplying member supplies toner, and one end of the toner conveying member is in the nip region (A2). Arranged,
The developer supply member is connected to a power supply (B1) for forming a toner supply electric field,
The toner transport member includes a plurality of electrodes and is connected to a power source (B2) that forms a transport electric field on the electrodes.
When transporting the toner supplied from the developer supply member to the toner transport member by applying a bias of the power supply (B1),
By applying a bias of the power source (B2), a toner conveying electric field direction is formed using one end of the toner conveying member disposed in the nip area (A2) as a conveying start point, and the toner moves toward the developing area (A1). It is configured as described above.

According to the developing device of the present invention, toner can be stably conveyed over time, and high-quality development without toner scattering and image smearing can be performed with high development efficiency.
In addition, since development can be performed with low voltage driving using the EH phenomenon, the durability of the latent image carrier is improved, and NOx is not generated, and environmental problems can be avoided.

Here, the toner conveying member may have any shape such as a cylindrical shape, a belt shape (an endless member), or a substrate shape. The cylindrical member does not need to be a perfect circle including a roller or the like.
Since the toner conveying member used in the developing device can have various shapes such as a cylindrical shape, a belt shape (endless member), or a substrate shape, this configuration can be used regardless of the configuration of the image forming apparatus. The developing device of the invention can be realized and can be mounted, and the specification can be flexibly handled.
Note that “endless” in the endless member indicates a member shape having no end, and is different from the end of the entire member structure in “one end of the toner conveying member” expressed in the present invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a description will be given with reference to FIG. FIG. 1 is a schematic configuration diagram for explaining a first embodiment of a developing device according to the present invention.
In the first embodiment, by applying a bias of the power source (B2), the toner electric field direction is divided at a predetermined portion of the electrode located in the nip region (A2) as a boundary. This is the case of the developing device configured to go to the developing area (A1) (forward direction) and the other to the opposite of A1.

  In the developing device 34 of FIG. 1, a magnetic brush roller 43 as a developer supply member is constituted by a nonmagnetic rotatable sleeve 48 incorporating a magnet member 47 having a plurality of magnetic poles. The magnet member 47 is fixedly arranged so that a magnetic force acts when the developer 62 passes through a predetermined location on the sleeve 48. The sleeve 48 used in this embodiment has a diameter of 18 mm and is sandblasted so that the surface roughness Rz (ten-point average roughness) falls within the range of 10 to 20 μm. The developer 62 is a two-component developer composed of a magnetic carrier (magnetic particles) 61 and a non-magnetic toner (toner) 60. As will be described later, the toner contains a charge control agent and an additive on the surface of the toner base. It is used that has a coating ratio of 50% or more of the additive to the surface area of the toner base.

  The magnet member 47 built in the magnetic brush roller 43 is arranged in the direction of rotation of the magnetic brush roller 43 from the restriction position by the restriction blade 46, and the N pole (N1), the S pole (S1), the N pole (N2), and the S pole (S2). ) And five magnetic poles of S pole (S3). The arrangement of the magnetic poles of the magnet member 47 is not limited to the configuration shown in FIG. 1, and may be set to other arrangements depending on the arrangement of the regulating blade 46 provided around the magnetic brush roller 43. Good. For example, as shown in another schematic configuration diagram of FIG. 2, the N pole (N1), the S pole (S1), the N pole (N2), and the S pole in the rotational direction of the magnetic brush roller 43 from the restriction location by the restriction blade 46. You may arrange | position the four magnetic poles of (S2). Further, in the example of the developing device 34 of FIG. 1, the magnet member 47 is fixedly arranged and the sleeve 48 is rotationally driven. However, the sleeve 48 is fixedly arranged and the roller-like magnet member inside thereof is rotated. You may comprise.

  Due to the magnetic force of the magnet member 47, a developer 62 composed of toner 60 and magnetic particles 61 is carried on the sleeve 48 in a brush shape. The toner 60 in the magnetic brush on the magnetic brush roller 43 is mixed with the magnetic particles 61 to obtain a specified charge amount. The charge amount of the toner on the magnetic brush roller 43 is preferably in the range of −10 to −40 [μC / g].

The magnetic particles 61 contain a metal or resin as a core and contain a magnetic material such as ferrite, and the surface layer is coated with a silicon resin or the like. The particle size of the magnetic particles 61 is preferably in the range of 20 to 50 μm. The resistance of the magnetic particles 61 is preferably in the range of 10 ⁴ to 10 ¹⁵ Ω in terms of dynamic resistance DR.

Here, the measurement of the dynamic resistance DR of the magnetic particle 61 can be performed as follows using the measuring apparatus shown in FIG. FIG. 3 is a schematic diagram showing a device configuration for measuring the dynamic resistance DR of the magnetic particles.
First, a rotatable sleeve 201 having a diameter of 20 mm and having a fixed magnet built in a predetermined position is set above the grounded base 200. A counter electrode (doctor) 202 having a facing area with a width W = 65 mm and a length L = 0.5 to 1 mm is opposed to the surface of the sleeve 201 with a gap g = 0.9 mm. Next, the sleeve 201 starts to be rotationally driven at a rotational speed of 600 rpm (linear speed of 628 mm / sec). Then, a predetermined amount (14 g) of magnetic particles to be measured is supported on the rotating sleeve 201, and the magnetic particles are stirred for 10 minutes by the rotation of the sleeve 201. Next, the current IRII [A] flowing between the sleeve 201 and the counter electrode 202 is measured by the ammeter 203 without applying a voltage to the sleeve 201. Next, an applied voltage E [V] of a withstand voltage upper limit level (400 V for high-resistance silicon-coated carrier to several V for iron powder carrier) is applied to sleeve 201 from DC power supply 204 for 5 minutes. In this embodiment, 200 V is applied. The current IRQ [A] flowing between the sleeve 201 and the counter electrode 202 with the voltage E applied is measured by the ammeter 203.
From these measurement results, the dynamic resistance DR [Ω] can be calculated using the following equation (1). In the formula (1), DR represents a dynamic resistance, and E represents an applied voltage.
DR = E / (IRQ-IRII) (1)

  Further, the toner conveying member (conveying member) 40 in FIG. 1 described above is a magnetic brush roller in the toner supply region (nip region for supplying toner) A2 adjacent to the magnetic pole N2 in the developer supply member (magnetic brush roller) 43. It is arranged so as to be in contact with the magnetic brush on 43 and to face the latent image carrier (photoconductor) 31 in the development area A1. That is, the transport member 42 transports the toner to the development area A1.

  Further, in the present embodiment, the distance at the closest portion between the regulating blade 46 and the magnetic brush roller 43 is set to 500 μm, and the magnetic pole N1 of the magnet member 47 facing the regulating blade 46 is positioned at the position facing the regulating blade 46. Further, the magnetic brush roller 43 is positioned at an angle of several degrees on the upstream side in the rotation direction. Thereby, the circulation flow of the developer 62 in the casing 41 can be easily formed.

  The regulating blade 46 comes into contact with the magnetic brush so as to regulate the amount of the developer 62 formed on the magnetic brush roller 43 at a portion facing the magnetic brush roller 43, and a predetermined amount of the developer enters the toner supply region. While being conveyed, frictional charging between the toner 60 and the magnetic particles 61 in the developer 62 is promoted.

  Further, the magnetic brush roller 43 is rotationally driven in the direction of arrow c in FIG. 1 (also in FIG. 2) by a rotation driving device (not shown), and only the toner 60 is supplied in the toner supply nip area (toner supply area) A2. Further, the gap between the toner conveying member 42 and the sleeve of the magnetic brush roller 43 in the toner supply region A2 was set to 1.1 mm.

In addition, a power source (B2) 49 is connected to an electrode for forming a transport electric field provided on the toner conveying member (conveying member) 42, and a plurality of voltages are applied thereto. The sleeve 48 of the developer supply member (magnetic brush roller) 43 is connected to a power supply (B1) 50 for applying a toner supply bias V _VXS for forming a toner supply electric field in the toner supply region A2. .

Next, the operation of the developing device 34 having the above configuration will be described.
The developer 62 contained in the casing 41 of FIG. 1 is a mixture of the toner 60 and the magnetic particles 61, and the rotational force of the stirring / conveying members 44, 45 and the sleeve 48 of the magnetic brush roller 43, the magnet member The toner 60 is agitated by the magnetic force of 47, and at that time, the toner 60 is given an electric charge by frictional charging with the magnetic particles 61.

  On the other hand, the developer 62 carried on the magnetic brush roller 43 is regulated by the regulating blade 46, and the toner in the magnetic brush is separated in the toner supply nip region A2, and a certain amount of toner 60 is formed by the toner supply bias. It is transferred to the conveying member by the applied electric field or the like, and the rest is returned to the casing 41.

The supply capability of the developer supply member (magnetic brush roller) in this embodiment is 0.6 [mg / cm ² ] at a potential difference of 1000 [V]. Here, the linear velocity of rotation of the sleeve 48 is 40 [cm / s], and the conveyance capacity per 1 cm width is 0.6 [mg / cm ² ] × 40 [cm / s] = 24 [mg / cm · s]. At this time, the amount of toner conveyed on the toner conveying member was 2.4 [mg / cm · s] as in the case of supply when calculated from the amount conveyed for 2 seconds at the end of the conveying member. However, as the voltage applied to the magnetic brush roller 403 was increased, the toner accumulated and stayed on the conveying member when the supply capacity exceeded 15 [mg / cm · s].

  However, as shown in FIGS. 4A and 4B, the order of bias application for determining the conveyance direction in the toner conveyance member (conveyance member) 40 is one boundary of the toner supply nip region (nip region) A2. The toner supplied in the supply nip region can be moved in both directions at the boundary by being arranged and controlled so as to be able to move in a so-called bi-directional direction (forward direction) toward the development region A1 and in the opposite direction to the development region. To move to.

That is, in the nip region A2 where the developer 62 exists between the developer supplying member (supplying member) 43 and the conveying member 40 as shown in FIG. 4A, the conveying member as shown in FIG. The conveying member is configured to be able to move the toner into the supply area in the forward direction divided and conveyed to the developing area and in the opposite direction to the former.
In FIG. 4A, the toner supplied from the supply member to the conveying member is conveyed to the developing area A1, but the toner conveyed in the reverse direction is brought into contact with the magnetic brush again in the nip area A2 to become a magnetic brush. It is collected and returned to the supply unit including the supply roller.

  With the above-described configuration, the transport amount is substantially reduced, and a multilayer toner layer is not formed on the transport member, so that toner accumulation and sticking are less likely to occur, and the toner can be transported smoothly.

In the above developing device configuration, it is preferable that the toner transport direction to the development area (A1) by the toner transport member is opposite to the developer transport direction by the developer supply member.
By reversing the toner transport direction and the developer supply direction, the toner can be transported in a transport electric field efficiently and stably. For example, the toner dissociated from the carrier (magnetic particles) of the two-component developer can be supplied to the toner conveying member without being captured again by the carrier or developer carrier. Therefore, the toner can be transported in a transport electric field more efficiently and stably.

In the developing device configuration, it is preferable that the boundary at a predetermined position of the electrode located in the nip region (A2) that divides the direction of the electric field of toner conveyance is changed by applying a bias of the power source (B2).
That is, by making the boundary at a predetermined position of the electrode variable, even if the toner volume or sticking occurs over time, the boundary that divides the direction of the toner electric field is changed to avoid this sticking part. Therefore, stable and continuous toner conveyance can be performed under suitable conditions.

Next, a second embodiment of the developing device according to the present invention will be described with reference to FIG. FIG. 5 is a schematic view for explaining a second embodiment of the developing device according to the present invention.
In the second embodiment, one end portion of the toner conveying member arranged to face the developer supply member is disposed in the nip region (A2), and this end portion is used as a conveyance start point in the direction of toner conveying electric field. And a developing device configured such that the toner is directed toward the developing region (A1).

  As described above, in the second embodiment, the end of the transport substrate, which is a toner transport member, exists in the toner supply width. As shown in FIG. 5, in the case of a transport substrate, one end of the transport substrate as a toner transport start point is set and arranged in the toner supply nip region (A2), and the width of the magnetic brush forming the supply nip is set. The supply is reduced. For example, by arranging one end of the transport substrate as a transport start point at the central portion in the closest region of the magnetic brush in the supply unit, the supplied toner is halved and the toner supply region is narrowed. Supply is appropriate and the amount of toner required is controlled stably and reliably without being deposited in multiple layers.

  That is, by arranging one end of the toner conveying member in the nip region (A2), the toner electric field direction is not divided in the nip region (A2) as in the first embodiment. Therefore, the toner can be transported efficiently and stably.

The operation in the second embodiment is performed except that one end portion of the toner transport member is used as a transport start point to form the toner transport electric field direction, and control is performed so as to move toward the development area (A1) with a suitable toner amount. Since the basic principle is the same as that of the first embodiment, detailed description thereof is omitted.
In the developing device configuration of the second embodiment, it is preferable that the toner transport direction to the development area (A1) by the toner transport member is opposite to the developer transport direction by the developer supply member. The reason is the same as in the case of the first embodiment.

Next, the developer and toner used in the developing device of the present invention will be described.
As shown in FIGS. 1 and 2, the developer 62 is preferably a two-component developer composed of (magnetic particles) 61 and nonmagnetic toner (toner) 60.
The toner is preferably one in which an additive is applied to the surface of a toner base composed mainly of a resin, and the coverage of the additive with respect to the surface area of the toner base is 50% or more.
Here, the coverage of the additive covering the surface of the toner base is given by the following formula (2).

In the above formula (1), Tn is the coverage of the additive, C is the amount of additive added to the toner base (wt%), r is the particle size of the additive, R is the particle size of the toner, ρ _r , ρ _R Represents the specific gravity of the additive and the specific gravity of the toner, respectively.

1 [rho _r, and 1 [rho _R, assuming that was actually adding additives 0.1μm diameter in the toner of 6μm diameter respectively, by changing the addition amount C obtaining coverage by the formula (2) Then, the relationship between the addition amount and the coverage is as shown in the graph of FIG. 6, and the coverage is about 50% with the addition amount of 3 wt%.
FIG. 7 compares the degree of occurrence of sticking to the additive coverage of the toner used. When the amount of additive is large, that is, when the coverage is 50% or more, the toner is conveyed. As a result, the fluidity is increased and the margin of sticking in the toner conveying member can be increased.

The toner 60 constituting the developer 62 is obtained by mixing a charge control agent (CCA) and a colorant with a resin such as polyester, polyol, styrene acryl, and the like, and an external additive such as silica, titanium oxide or the like around it. Fluidity is enhanced by adding an agent.
The particle size of the additive is usually in the range of 0.1 to 1.5 μm. Examples of the colorant used include carbon black, phthalocyanine blue, quinacridone, and carmine. As the toner 60, a toner obtained by externally adding the above-mentioned various additives to a base toner in which a wax or the like is dispersed and mixed as necessary can also be used.

The volume average particle diameter of the toner 60 is preferably in the range of 3 to 12 μm. The toner used in this embodiment has a volume average particle diameter of 3 to 7 μm. By using a particle diameter in this range, it is possible to sufficiently cope with a high-resolution image of 1200 dpi or more.
In the present embodiment, the toner 60 having a negative charge polarity is used. However, a toner having a positive charge polarity according to the charge polarity of the latent image carrier (photoconductor) 31 may be used. Good.

Next, taking as an example the case where the toner conveying member is in the form of a substrate (conveying substrate), the toner conveyance in the developing area and the areas before and after the developing apparatus will be described in detail with reference to FIG.
The developing device has an electric field for transporting, hopping, and collecting the toner T supplied from a (photosensitive drum) 10 and a developer supply member (not shown) that holds the developer on the surface and forms and transports a magnetic brush. And a toner conveying member (conveying substrate) 1 having a plurality of generated electrodes 102. The transport substrate 1 transports the toner to the development area (A1) facing the latent image carrier. The transfer substrate 1 is applied with drive waveforms Va1 to Vc1 and Va2 to Vc2 having different n phases (here, three phases) for generating a required electric field from a drive circuit 2 of a power supply (B2) (not shown). Is done.

  Here, the conveyance substrate 1 transfers the toner T to the vicinity of the photosensitive drum 10 in relation to the range of the electrode 102 that gives the driving waveforms Va1 to Vc1 and Va2 to Vc2 and the photosensitive drum 10 that is a latent image carrier. A transport region 11, a development region 12 for forming a toner image by attaching toner T to the latent image on the photosensitive drum 1, and a region after passing through the development region for collecting the toner T on the transport substrate 1 side (this , Hereinafter referred to as “collection area”).

  In the developing device, the toner T is transferred to the vicinity of the photosensitive drum 10 in the conveying area 11 of the conveying substrate 1, and the toner T is drummed on the image portion of the latent image on the photosensitive drum 10 in the developing area 12. An electric field for developing the toner T by adhering the toner T to the latent image by forming an electric field in the direction toward the opposite side (conveying substrate side) of the toner T toward the non-image portion. In the recovery area 13, the toner T forms an electric field in the direction toward the opposite side (conveying substrate side) from the photosensitive drum 10 for both the image portion and the non-image portion of the latent image.

  As a result, in the developing region 12, the toner adheres to the latent image on the latent image carrier (photosensitive drum) 10 to be visualized, and the toner that has not contributed to the development rotates (moves) the photosensitive drum 10. Direction) Since the toner is collected on the transport substrate 1 side in the downstream collection area, generation of scattered toner is prevented. The collection area 13 is located downstream of the development area 12 in the moving direction of the latent image carrier 10, so that the floating toner can be reliably collected.

  First, the configuration of the transport substrate 1 in the developing device shown in FIG. 8 will be described in detail with reference to FIGS. 9 is a developed plan view for explaining the configuration of the transfer substrate 1 in FIG. 8, FIG. 10 is a sectional view taken along the line AA in FIG. 9, and FIG. 11 is taken along the line BB in FIG. 12 is a cross-sectional view taken along the line CC of FIG. 9, and FIG. 13 (6) is a cross-sectional view taken along the line DD of FIG.

  The transport substrate 1 is a set of three electrodes (transport electrodes) 102a, 102b, 102c (these are also collectively referred to as “electrodes 102”) on a base substrate (support substrate) 101 at a predetermined interval. It is repeatedly formed and arranged in a direction substantially perpendicular to the toner transfer direction along the toner transfer direction (toner traveling direction, toner moving direction: indicated by the arrow in FIGS. 9 and 10), and a transport surface is formed thereon. A surface protective layer 103 made of an inorganic or organic insulating material, which becomes an insulating transport surface forming member and serves as a protective film covering the surface of the electrode 102, is laminated. Here, the surface protective layer 103 forms the transport surface, but a surface layer having excellent compatibility with the powder (toner) can be additionally formed on the surface protective layer 103.

  On both sides of these electrodes 102a, 102b, 102c, common electrodes 105a, 105b, 105c (these are also collectively referred to as “common electrode 105”) interconnected with the electrodes 102a, 102b, 102c at both ends, respectively, are transported with toner. It is provided along the direction, that is, in a direction substantially orthogonal to the individual electrodes. In this case, the width of the common electrode 105 (this width is the width in the direction orthogonal to the toner transfer direction) is larger than the width of the electrode 102 (this width is the width along the toner transfer direction). In FIG. 9, the common electrode 105 is divided into the common electrodes 105 a 1, 105 b 1, and 105 c 1 in the transport region 11, the common electrodes 105 a 2, 105 b 2, and 105 c 2 in the development region 12, and the common electrodes 105 a 3, 105 b 3, and 105 c 3 in the collection region 13. It is shown separately.

  Here, after the pattern of the common electrodes 105a, 105b, and 105c is formed on the support substrate 101, an interlayer insulating film 107 (which may be the same material as the surface protective layer 103 or a different material) is formed, and this interlayer insulating film After forming the contact hole 108 in 107, the electrodes 102a, 102b, 102c are formed to interconnect the electrodes 102a, 102b, 102c and the common electrodes 105a, 105b, 105c, respectively.

  An interlayer insulating film is formed on a pattern in which the electrode 102a and the common electrode 105a are integrally formed, a pattern in which the electrode 102b and the common electrode 105b are integrally formed is formed on the interlayer insulating film, and an interlayer insulating film is further formed. Thus, a pattern in which the electrode 102c and the common electrode 105c are integrally formed is formed on the interlayer insulating film, that is, the electrode can be formed in a three-layer structure, or the integral formation and the interconnection by the contact hole Can also be mixed.

  Further, although not shown, these common electrodes 105a, 105b, 105c are provided with drive signal application input terminals for inputting drive signals (drive waveforms) Va, Vb, Vc from the drive circuit 2. This drive signal input terminal may be provided on the back surface side of the support substrate 101 and connected to the common electrode 105 through a through hole, or may be provided on an interlayer insulating film 107 described later.

Here, as the support substrate 101, a substrate made of an insulating material such as a glass substrate, a resin substrate or a ceramic substrate, or a substrate made of a conductive material such as SUS, and an insulating film such as SiO ₂ is formed, Alternatively, a substrate made of a flexible deformable material such as a polyimide film can be used.

  For the electrode 102, a conductive material such as Al or Ni—Cr is formed on the support substrate 101 with a thickness of 0.1 to 10 μm, preferably 0.5 to 2.0 μm, and this is formed using a photolithography technique or the like. The pattern is formed into a required electrode shape. The width L of the plurality of electrodes 102 in the powder (toner) traveling direction is set to be 1 to 20 times the average particle diameter of the powder to be moved, and between the electrodes 102 and 102 in the powder (toner) traveling direction. The interval R is also set to 1 to 20 times the average particle diameter of the powder to be moved.

As the surface protective layer 103, for example, SiO ₂ , TiO ₂ , TiO ₄ , SiON, BN, TiN, Ta ₂ O _5, etc. are formed in a thickness of 0.5 to 10 μm, preferably 0.5 to 3 μm. And formed. In addition, inorganic nitride compounds such as SiN, Bn, and W can be used. In particular, since the charge amount of the charged toner tends to decrease in the middle of conveyance when the surface hydroxyl groups increase, inorganic nitride compounds with few surface hydroxyl groups (SiOH, silatol groups) are preferable.

Next, the principle of electrostatic transport of toner on the transport substrate 1 configured as described above will be described.
By applying an n-phase driving waveform to the plurality of electrodes 102 of the transport substrate 1, a phase shift electric field (same as “traveling wave electric field” or “transport electric field”) is generated by the plurality of electrodes 102, and the transport substrate The charged toner on 1 receives a repulsive force and / or a suction force and moves in the transfer direction including hopping and conveyance.

  For example, with respect to the plurality of electrodes 102 of the transport substrate 1, as shown in FIG. 14, a three-phase pulsed drive waveform (drive signal) Va (A) that changes between the ground G (0 V) and the positive voltage + as shown in FIG. Phase), Vb (B phase), and Vc (C phase) are applied at different timings.

  At this time, as shown in FIG. 15, negatively charged toner T is present on the transport substrate 1, and “G”, “G” ”,“ + ”,“ G ”, and“ G ”are applied, the negatively charged toner T is positioned on the“ + ”electrode 102.

  At the next timing, “+”, “G”, “G”, “+”, and “G” are respectively applied to the plurality of electrodes 102 as shown in (2). Since a repulsive force acts between the left “G” electrode 102 and an attractive force acts between the right “+” electrode 102, the negatively charged toner T moves to the “+” electrode 102 side. To do. Further, as shown in (3), “G”, “+”, “G”, “G”, “+” are respectively applied to the plurality of electrodes 102 at the next timing, and the same applies to the negatively charged toner T. Therefore, the negatively charged toner T further moves to the “+” electrode 102 side.

  In this way, by applying a multi-phase driving waveform whose voltage changes to the plurality of electrodes 102, a traveling wave electric field (carrier electric field) is generated on the carrier substrate 1 and is negatively charged in the traveling direction of the traveling wave electric field. The toner T moves while carrying and hopping. In the case of positively charged toner, the drive waveform changes in the same direction by reversing the drive waveform change pattern.

  More specifically, referring to FIG. 16, as shown in FIG. 16A, the electrodes A to F of the transport substrate 1 are all 0 V (G), and the negatively charged toner T is placed on the transport substrate 1. When “+” is applied to the electrodes A and D as shown in FIG. 4B, the negatively charged toner T is attracted to the electrodes A and D and moves onto the electrodes A and D. At the next timing, as shown in FIG. 5C, when the electrodes A and D are both “0” and “+” is applied to the electrodes B and E, the toner T on the electrodes A and D is displayed. Receives the repulsive force and the suction force of the electrodes B and E, so that the negatively charged toner T is transferred to the electrode B and the electrode E. Furthermore, at the next timing, as shown in FIG. 4D, when the electrodes B and E are both “0” and “+” is applied to the electrodes C and F, The toner T receives a repulsive force and also receives the suction force of the electrodes C and F, so that the negatively charged toner T is transferred to the electrodes C and F. In this way, the negatively charged toner is sequentially transferred rightward in the drawing by the traveling wave electric field.

Next, the overall configuration of the drive circuit 2 will be described with reference to FIG.
The drive circuit 2 includes a pulse signal generation circuit 21 that generates and outputs a pulse signal, and waveform amplifiers 22a and 22b that generate and output drive waveforms Va1, Vb1, and Vc1 by inputting the pulse signal from the pulse signal generation circuit 21. 22c, and waveform amplifiers 23a, 23b, and 23c that receive the pulse signals from the pulse signal generation circuit 21 and generate and output the drive waveforms Va2, Vb2, and Vc2.

  The pulse signal generating circuit 21 receives, for example, a logic level input pulse, and includes two sets of pulses that are phase-shifted to 120 °, and switching means included in the next stage waveform amplifiers 22a to 22c and 23a to 23c, for example, transistors To generate and output a pulse signal having an output voltage of 10 to 15 V at a level capable of performing 100 V switching.

  For example, as shown in FIG. 18, the waveform amplifiers 22a, 22b, and 22c apply + 100V application time ta to each electrode 102 in the transport region 11 and each electrode 102 in the recovery region 13 shown in FIG. Three-phase drive waveforms (drive pulses) Va1, Vb1, and Vc1 are applied, which is set to about 33%, which is 1/3 of the repetition period tf (this is referred to as “transport voltage pattern” or “collected transport voltage pattern”). .

  For example, as shown in FIG. 19 or FIG. 20, the waveform amplifiers 23a, 23b, and 23c repeat the application time ta of + 100V or 0V for each phase to 2/3 of the period tf. Is set to about 67% (this is referred to as a “hopping voltage pattern”). Three-phase drive waveforms (drive pulses) Va2, Vb2, and Vc2 are applied.

Next, the developing bias will be described.
As described above, in the EH development, the electrostatic latent image on the latent image carrier can be reversely developed by the one-component development method by hopping the toner. That is, in the development area, means for forming an electric field in a direction in which the toner is directed to the latent image carrier side with respect to the image portion of the latent image and the toner is directed to the opposite side of the latent image carrier body with respect to the non-image portion. By providing, development can be performed.

  For example, in the case of a pulsed voltage waveform transitioning from 0 to −100 V as in the driving waveform of the hopping voltage pattern shown in FIG. 20 described above, when the non-image portion potential on the latent image carrier is lower than −100 V, For the image portion, the toner is directed to the latent image carrier, and for the non-image portion, the toner is directed to the opposite side of the latent image carrier. In this case, it was confirmed that when the potential of the non-image portion of the latent image is −150V or −170V described later, the toner moves toward the latent image carrier.

Further, when the driving waveform of the hopping voltage pattern is a pulsed voltage waveform that transitions between 20 V and −80 V, the pulsed driving waveform is also obtained when the potential of the image portion is about 0 V and the potential of the non-image portion is −110 V. Similarly, since the low level potential is between the image portion potential of the latent image and the non-image portion potential, the toner is directed toward the latent image carrier for the image portion and the toner is applied to the non-image portion. It goes to the opposite side to the latent image carrier.
In short, by setting the low-level potential of the pulse-shaped drive waveform to a potential between the potential of the latent image portion and the non-image portion, toner adhesion to the non-image portion is prevented and high quality is achieved. Development can be performed.

  In this way, in the EH development, since toner is hopping, the toner is attracted and adhered to the image portion of the latent image, and the toner is repelled and not adhered to the non-image portion. At this time, since the toner that has already been hopped does not generate an adsorbing force with the transport substrate 1, it can be easily transferred to the latent image carrier and can be developed with high image quality. Can be performed at a low voltage.

  That is, in the conventional so-called jumping development method, in order to peel off the charged toner from the developing roller and transfer it to the photosensitive member, an applied voltage higher than the adhesion force of the toner to the developing roller is required. A bias voltage must be applied. On the other hand, according to the present invention, the adhesion force of the toner is usually 50 to 200 nN. However, since the adhesion force to the transport substrate 1 becomes substantially zero because of hopping on the transport substrate 1, the toner is removed. The force for peeling from the transport substrate 1 becomes unnecessary, and the toner can be sufficiently transferred to the latent image carrier side with a low voltage.

  In addition, even when the voltage applied between the electrodes 102 and 102 is a low voltage of | 150 to 100 | V or less, the generated electric field has a very large value, and the toner adhering to the surface of the electrode 102 is easily peeled off. It is possible to fly, hop. Further, ozone or NOx generated when charging a photoconductor such as OPC is very little or can be eliminated, which is very advantageous for environmental problems and durability of the photoconductor.

  Therefore, there is no need for a high voltage bias of 500 V to several KV applied between the developing roller and the photosensitive member in order to peel off toner adhering to the surface of the conventional developing roller or carrier. The latent image can be formed and developed by setting the charging potential of the photosensitive member to a very low value.

For example, an OPC photoconductor is used as a latent image carrier, the surface CTL (Charge Transport Layer) thickness is 15 μm, the relative dielectric constant ε is 3, and the charge density of the charged toner is (−3E-4). In the case of C / m ² , the OPC surface potential is about −170 V. In this case, when a pulsed drive voltage of 0 to −100 V and a duty of 50% is applied as an applied voltage to the electrode of the transport substrate, on average, If the toner is -50V and the toner is negatively charged, the electric field between the electrode of the transport substrate and the OPC photosensitive member has the relationship described above.

  At this time, if the gap (interval) between the transport substrate and the OPC photosensitive member is 0.2 to 0.3 mm, the development can be sufficiently performed. Depending on the Q / M of the toner, the voltage applied to the electrode of the transport substrate, the printing speed, that is, the rotational speed of the OPC photoconductor, in the case of negatively charged toner, at least the potential for charging the OPC photoconductor is −300 V or less, or development In the case of a configuration in which efficiency is prioritized, development can be sufficiently performed even at −100V or less. Note that the charging potential in the case of positive charging is a positive potential.

  By the way, the above-described EH development is performed by hopping the toner on the transport substrate 1 to reduce the adsorption force to the transport substrate 1 to 0, but according to the study by the present inventors, By simply hopping the toner on the transport substrate, it is guaranteed that the hopped toner will adhere to the latent image on the latent image carrier 10 even if the hopped toner has progress toward the latent image carrier. It was also confirmed that toner scattering occurred.

  Therefore, as a result of earnest research on the EH development, the present inventors have selectively and reliably adhered the hopped toner to the image portion of the latent image carrier and not to the non-image portion. It has been found that there is no so-called soiling.

  That is, the relationship between the potential of the latent image (surface potential) of the latent image carrier and the potential applied to the transport substrate (electric field to be generated) is set to a predetermined relationship. That is, as described above, an electric field is generated in which the toner is directed toward the latent image carrier for the latent image portion of the latent image carrier and the toner is directed toward the transport substrate for the non-image portion. As a result, the toner adheres securely to the image portion of the latent image, and the toner toward the non-image portion is pushed back to the transport substrate side, so that the toner hopped from the transport substrate is efficiently used for development, Scattering can be prevented and high-quality development by low voltage driving can be realized.

  In this case, the average value (average value potential) of the potential applied to the electrode of the transport substrate is set to a potential between the potential of the image portion of the latent image on the latent image carrier and the potential of the non-image portion. As described above, it is possible to generate an electric field in which the toner is directed toward the latent image carrier for the latent image portion of the latent image carrier and the toner is directed toward the transport substrate for the non-image portion.

Next, the width (electrode width) L and electrode spacing R of the plurality of electrodes 102 provided on the transport substrate 1 for transporting and hopping toner, and the surface protective layer 103 will be described.
The electrode width L and the electrode interval R on the transport substrate 1 greatly affect toner transport efficiency and hopping efficiency. That is, the toner between the electrodes moves to the adjacent electrode on the substrate surface by a substantially horizontal electric field. On the other hand, since the toner on the electrode is given an initial velocity having at least a component in the vertical direction, most of the toner flies away from the substrate surface.

  In particular, since the toner near the electrode end surface moves over the adjacent electrode, when the electrode width L is wide, the number of toners on the electrode increases, and the toner having a large moving distance increases. Conveyance efficiency increases. However, if the electrode width L is too wide, the electric field strength in the vicinity of the center of the electrode is lowered, so that the toner adheres to the electrode and the transport efficiency is lowered. As a result of intensive studies, the present inventors have found that there is an appropriate electrode width for efficiently conveying and hopping powder at a low voltage.

  The electrode interval R determines the electric field strength between the electrodes from the relationship between the distance and the applied voltage. The narrower the interval R, the stronger the electric field strength, and the easier the initial speed of conveyance and hopping. However, for toner that moves from electrode to electrode, the distance traveled once is shortened, and the movement efficiency cannot be increased unless the drive frequency is increased. In this regard, as a result of intensive studies, the present inventors have found that there is an appropriate electrode interval for efficiently conveying and hopping powder at a low voltage.

  Furthermore, it has also been found that the thickness of the surface protective layer covering the electrode surface also affects the electric field strength on the electrode surface, in particular, the influence of the vertical component on the electric field lines is large and determines the hopping efficiency.

  Therefore, by appropriately setting the relationship between the electrode width of the transport substrate, the electrode interval, and the surface protective layer thickness, the toner adsorption problem on the electrode surface can be solved, and efficient movement can be performed at a low voltage.

  More specifically, first, the electrode width L is a width dimension for carrying and hopping at least one toner when the electrode width L is set to one time the toner diameter (powder diameter). On the other hand, if it is narrower than this, the electric field acting on the toner is reduced, and the conveying force and the flying force are lowered, which is not sufficient for practical use.

  In addition, as the electrode width L increases, the electric lines of force incline in the direction of travel (horizontal direction), particularly in the vicinity of the center of the upper surface of the electrode, and a region with a weak vertical electric field is generated. Become. When the electrode width L is too wide, in an extreme case, the image force according to the charged charge of the toner, the van der Waals force, the adsorbing force due to moisture, etc. may be superior, and toner deposition may occur.

  From the efficiency of conveyance and hopping, if the width is such that about 20 toners are placed on the electrode, adsorption is unlikely to occur, and the conveyance and hopping operations can be efficiently performed with a low voltage drive waveform of about 100V. If it is wider than that, a region where adsorption occurs partially occurs. For example, when the average particle diameter of the toner is 5 μm, it corresponds to a range of 5 to 100 μm.

  A more preferable range of the electrode width L is not less than 2 times and not more than 10 times the average particle diameter of the toner in order to more efficiently drive the applied voltage based on the drive waveform at a low voltage of 100 V or less. By setting the electrode width L within this range, the decrease in electric field strength near the center of the electrode surface can be suppressed to 1/3 or less, and the decrease in hopping efficiency is 10% or less, resulting in a significant decrease in efficiency. Disappears. This corresponds to a range of 10 to 50 μm, for example, when the average particle diameter of the toner is 5 μm.

  More preferably, the electrode width L is in the range of 2 to 6 times the average particle size of the toner. This is, for example, a range corresponding to 10 to 30 μm when the average particle diameter of the toner is 5 μm. It has been found that efficiency within this range is very good.

  Here, as shown in FIG. 21, the width (electrode width) L of the electrode 102 (same as the reference numeral in FIGS. 9 to 13) on the transport substrate 1 (same as the reference numeral in FIGS. 9 to 13) is 30 μm, and the electrode interval R Is 30 μm, the thickness of the electrode 102 is 5 μm, the thickness of the surface protective layer 103 (same as the reference numerals in FIGS. 10 to 13) is 0.1 μm, and +100 V and 0 V are applied to the two adjacent electrodes 12 respectively, and the electrode width L FIG. 22 and FIG. 23 show the results of measuring the strength of the carrier electric field TE and the hopping electric field HE with respect to the electrode interval R.

  Each evaluation data is a result of actual measurement and evaluation by simulation and actual measurement, and behavior of particles by high-speed video. In FIG. 21, two electrodes 102 are shown for easy understanding of details, but an actual simulation and experiment evaluate an area having a sufficient number of electrodes as described above. The toner T has a particle size of 8 μm and a charge amount of −20 μC / g.

  The electric field strengths shown in FIGS. 22 and 23 are values of representative points on the surface of the electrode, and the representative point TEa of the carrier electric field TE is a point above the electrode end 5 μm shown in FIG. 21 and a representative point HEa of the hopping electric field HE. Is a point 5 μm above the center of the electrode shown in FIG. 21 and corresponds to a representative point having the strongest electric field acting on the toner in the X and Y directions, respectively.

  From FIG. 22 and FIG. 23, the electric field capable of imparting a force acting on toner conveyance and hopping is (5E + 5) V / m or more, and the preferred electric field without the problem of adsorption is (1E + 6) V / m or more. It can be seen that a more preferable electric field capable of imparting a sufficient force is in the range of (2E + 6) V / m or more.

  Regarding the electrode spacing R, the electric field strength in the transport direction decreases as the spacing increases, and therefore the value corresponding to the range of the electric field strength is the same. As described above, 20 times or more the average particle diameter of the toner, 20 It is not more than twice, preferably not less than 2 times and not more than 10 times, more preferably not less than 2 times and not more than 6 times.

  Further, from FIG. 23, the hopping efficiency decreases as the electrode spacing R increases, but practical hopping efficiency can be obtained up to 20 times the average particle diameter of the toner. If the average particle diameter of the toner exceeds 20 times, the adsorbing force of a large amount of toner cannot be ignored, and a toner with no hopping is generated. In this respect, the electrode interval R is 20 times or less of the average particle diameter of the toner. There is a need to.

  As described above, the electric field strength in the Y direction is determined by the electrode width L and the electrode interval R, and the narrower the electric field strength is. Further, the electric field strength in the X direction near the end of the electrode is also determined by the electrode interval R, and the narrower the electric field strength is.

  As described above, the width of the electrode in the toner traveling direction is 1 to 20 times the average particle diameter of the toner, and the distance in the toner traveling direction of the electrode is 1 to 20 times the average particle diameter of the powder. By setting the following, the electrostatic force sufficient to transport and hop toner can be obtained for the charged toner on or between the electrodes by overcoming its mirror image force, van der Waals force, and other attractive forces. The toner can be prevented from staying, and can be stably and efficiently conveyed and hopped at a low voltage.

  According to the study by the present inventors, when the average particle diameter of the toner is 2 to 10 μm and Q / m is negatively charged, it is −3 to −40 μC / g, more preferably −10 to −30 μC / g, positive In the case of charging, when the pressure is +3 to +40 μC / g, more preferably +10 to +30 μC / g, the transport and hopping by the electrode configuration described above can be efficiently performed.

Next, the surface protective layer 103 shown in FIGS.
By providing a surface protective layer, there is no contamination of the electrodes, adhesion of fine particles, etc., the surface can be maintained under conditions suitable for conveyance, creeping leaks in high humidity environments can be avoided, and Q / m fluctuations can be achieved. In addition, the charged charge amount of the powder can be stably maintained.

  Here, FIG. 24 shows a result obtained by calculating the electric field strength in the X direction when the thickness of the surface protective layer 103 is changed in the range of 0.1 to 80 μm in FIG.

  The dielectric constant ε of the surface protective layer 13 is higher than that of air, and usually ε = 2 or more. As can be seen from FIG. 24, when the film thickness of the surface protective layer (thickness from the electrode surface) is too thick, the electric field strength acting on the toner on the surface decreases. Therefore, considering the transport efficiency, temperature and humidity resistance environment, etc., the surface protective layer thickness that can be practically used without causing a decrease in efficiency for the transport operation is 10 μm or less, more preferably the efficiency is decreased. Is 5 μm or less, which is suppressed to several percent.

  Examples of the electric field strength acting on the electrode surface hopping are shown in FIGS. 25 shows an example in which the thickness of the surface protective layer is 5 μm, and FIG. 26 shows an example in which the thickness of the surface protective layer is 30 μm. In both cases, the applied voltage is 0 V and 100 V with an electrode width of 30 μm and an electrode interval of 30 μm.

  As can be seen from each of these figures, as the thickness of the surface protective layer increases, the electric field from the protective layer having a dielectric constant higher than that of air to the adjacent electrode increases, so that the vertical component of the surface decreases and the protective layer is protected. The electric field strength acting on the toner on the surface is reduced by the thickness of the layer.

That is, the vertical component electric field lines acting on hopping greatly depend on the protective layer thickness. An electric field that can efficiently apply a force that acts on hopping at a low voltage of about 100 V is (1E + 6) V / m or more as a preferable electric field that does not have a problem of adsorption, and a more preferable electric field that can apply a sufficient force is (2E + 6) ) V / m or more, and the protective layer thickness for that is 10 μm or less, more preferably 5 μm or less.
As a material for the surface protective layer, a material having a specific resistance of 10E6 Ωcm or more and a dielectric constant ε of 2 or more is preferably used.

  Thus, by providing a surface protective layer covering the electrode surface and setting the thickness of the surface protective layer to 10 μm or less, the electric field of the vertical component can be made to act more strongly on the powder, and hopping Can increase the efficiency.

  Regarding the relationship with the charging potential of the latent image carrier, when the toner is a negatively charged toner, the surface charging potential of the latent image carrier is −300 V or less, and when the toner is a positively charged toner, Set the charging potential to + 300V or less. That is, the charged potential on the surface of the latent image carrier is set to | 300 | V or less.

  As a result, as described above, when the electrodes are fine pitched, the generated electric field has a very large value even when the voltage applied between the electrodes 102 and 102 is a low voltage of 150 to 100 V or less. The toner adhering to the surface can be easily peeled off, flying and hopping. Further, ozone or NOx generated when charging a photoconductor such as OPC is very little or can be eliminated, which is very advantageous for environmental problems and durability of the photoconductor.

  Next, the relationship between the charged polarity of the toner to be moved and the material of the outermost layer of the surface protective layer will be described. The outermost layer of the surface protective layer refers to a layer that forms a surface in contact with the powder when the surface protective layer is formed of a plurality of layers when the surface protective layer is a single layer. .

When conveying toner used in an image forming apparatus, the resin material occupying 80% or more of the toner is considered to have melting temperature, transparency in color, etc., and is generally a styrene-acrylic copolymer, Polyester resin, epoxy resin, polyol resin and the like are used.
Although the charging characteristics of the toner are affected by these resins, a charge control agent is added for the purpose of positively controlling the charge amount. As a charge control agent for black toner (BK), for example, nigrosine dyes and quaternary ammonium salts are used in the case of positive charge, and in the case of negative charge, for example, an azo metal-containing complex or a salicylic acid metal complex is used. The As the charge control agent for color toners, for example, quaternary ammonium salts and imidazole complexes are used in the case of positive charge, and in the case of negative charge, for example, salicylic acid metal complexes, salts, and organic boron salts are used. The

  On the other hand, these toners are repeatedly contacted and peeled off from the surface protective layer by the operation of transporting or hopping on the transport substrate by a phase-shifting electric field (traveling wave electric field), so that the toner is affected by frictional charging. However, the charge amount and polarity are determined by the mutual charge series of the materials.

  In this case, it is possible to improve the efficiency for conveyance, hopping, and photoconductor development by maintaining the toner charge amount to a saturation charge amount determined mainly by the charge control agent, or to some extent.

  Therefore, when the toner charging polarity is negative, at least the material of the layer that forms the outermost surface of the surface protective layer, the vicinity of the material used as the toner charge control agent on the triboelectric charging series (the region of conveyance and hopping is It is preferable to use a material located on the right end side or a material located on the positive end side. For example, when the charge control agent is a salicylic acid metal complex, a polyamide system located in the vicinity thereof is preferable. For example, polyamide (nylon: trade name) 66, nylon (trade name) 11 or the like is used.

  Further, when the toner charging polarity is positive, at least as the material of the layer that forms the outermost surface of the surface protective layer, the vicinity of the material used as the toner charge control agent on the triboelectric charging series (the region of conveyance and hopping is It is preferable to use a material located on the negative end side or a material located on the negative end side. For example, when the charge control agent is a quaternary ammonium salt, the vicinity thereof or a Teflon (registered trademark) material such as fluorine is used.

Next, the thickness of the electrode 102 will be described.
As described above, when a surface protective layer having a thickness of several μm is formed so as to cover the electrode surface, unevenness is generated on the surface of the transport substrate corresponding to the region where the electrode is present and not present under the surface protective layer. . At this time, by forming the electrode in a thin layer having a thickness of 3 μm or less, it is possible to smoothly convey a powder of about 5 μm, such as toner, without causing a problem of unevenness on the surface of the protective film. Therefore, if the electrode is formed to a thickness of 3 μm or less, a transport substrate having a thin surface protective layer can be put into practical use without the need for a flattening process on the transport substrate surface, and the electric field strength for transport and hopping can be increased. The drop does not occur, and more efficient conveyance and hopping can be performed.

According to the method of developing the latent image on the latent image carrier using the developing device of the present invention, the toner can be stably supplied, and high quality development can be performed with high development efficiency. .
Further, if the image forming method using the above developing method is used, high-quality development can be achieved by supplying stable toner, and a high-quality image free from toner scattering and scumming can be formed.

Hereinafter, an image forming apparatus, a process cartridge, and the like having the developing device of the present invention will be described.
A first embodiment of an image forming apparatus according to the present invention including a developing device according to the present invention will be described with reference to FIG.
The overall outline and operation of this image forming apparatus will be described. A photosensitive drum 301 serving as a latent image carrier is formed by forming a photosensitive layer 303 on a substrate 302 and is driven to rotate in the direction indicated by an arrow in FIG. . The photosensitive drum 301 is uniformly charged by the charging device 305, and an electrostatic latent image is formed on the surface of the photosensitive drum 301 by writing with a laser beam corresponding to an image read from the exposure unit 306.

  Then, the electrostatic latent image on the surface of the photosensitive drum 301 is visualized by being attached with toner by the developing device 316 according to the present invention, and the visible image is transferred from the paper feed cassette 317. The transfer paper 319 transferred to the paper (recording medium) 319 by the transfer roller 320 to which the voltage from the transfer power source 321 is applied and the visible image transferred thereon is separated from the surface of the photosensitive drum 301, and then the fixing unit. The visible image is fixed through the rollers 323 and discharged to a discharge tray outside the apparatus.

  On the other hand, the toner remaining on the surface of the photosensitive drum 301 after the transfer is removed by the cleaning device 325, and the charge remaining on the surface of the photosensitive drum 301 is erased by the charge eliminating lamp 326.

  Therefore, the developing device 316 will be described. In the developing device 316, the charging brushes 331a and 331b are arranged so as to be in contact with each other and rotate as an example of a member for charging the toner, which is powder, and the toner tank 332 is rotated. The toner T fed from is subjected to friction by the brushes 331a and 331b and is charged.

  After being charged by the supply unit, the toner is sent to the transport substrate 341, transported and hopped on the transport substrate 341, and sent to the development area facing the latent image carrier 301, after performing the required development. The toner used for the development falls from the end of the transport substrate 341 and is sent back to the member (charging brush 331b) for charging the toner by the reverse transport substrate 342.

  Note that the configurations of the transfer substrate 341 and the reverse transfer substrate 342 are the same as those of the transfer substrate 1, and the configuration of a drive circuit that applies a drive waveform to each electrode of the transfer substrate 341 and the reverse transfer substrate 342 is also omitted. However, this is the same as that described in each embodiment of the developing device.

  With this configuration, it is possible to form a high-quality image by developing with high development quality with less scattered toner.

Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 2 is an overall schematic configuration diagram of the image forming apparatus.
The overall outline and operation of this image forming apparatus will be described. A photosensitive drum 401 (for example, an organic photosensitive member: OPC), which is a latent image carrier, is driven to rotate clockwise in FIG. When a document is placed on the contact glass 402 and a print start switch (not shown) is pressed, a scanning optical system 405 including a document illumination light source 403 and a mirror 404 and a scanning optical system 408 including mirrors 406 and 407 move. The original image is read.

  Here, the scanned document image is read as an image signal by the image reading element 410 disposed behind the lens 409, and the read image signal is digitized and subjected to image processing. Then, a laser diode (LD) is driven by the signal subjected to the image processing, and laser light from the laser diode is reflected by the polygon mirror 413 and then irradiated onto the photosensitive drum 401 via the mirror 414. The photosensitive drum 401 is uniformly charged by a charging device 415, and an electrostatic latent image is formed on the surface of the photosensitive drum 401 by writing with a laser beam.

  The electrostatic latent image on the surface of the photosensitive drum 401 is visualized by attaching toner to the developing device 416 according to the present invention, and the visible image (toner image) is supplied to the paper feeding unit 417A or 417B. To the transfer paper (recording medium) 419 fed from the feed roller 418A or 418B by the corona discharge of the transfer charger 420. The transfer sheet 419 to which the visible image is transferred is separated from the surface of the photosensitive drum 401 by the separation charger 421, conveyed by the conveyance belt 422, and passes through the pressure contact portion of the fixing roller pair 423 so that the visible image is transferred. The paper is fixed and discharged to a discharge tray 424 outside the apparatus.

  On the other hand, the toner remaining on the surface of the photosensitive drum 401 after the transfer is removed by the cleaning device 425, and the electric charge remaining on the surface of the photosensitive drum 401 is erased by the static elimination lamp 426.

  FIG. 29 is an enlarged view of a main part of the developing device 416 in FIG. As shown in FIG. 29, a toner hopper 431 for storing toner, an agitator 432 for agitating the toner in the toner hopper 431, and a charging roller 434 for charging the toner in the toner hopper 431 and supplying it to the toner box 433. And a doctor blade 435 disposed in contact with the peripheral surface of the charging roller 434.

  The toner supplied to the toner box 433 is transported for developing and transported for hopping, and the toner that has not been used for development falling from the end of the transporting substrate 441 is charged. And a reverse transport substrate 442 that transports the member (the charging roller 434) in a returning direction.

Note that, as described in the first embodiment of the image forming apparatus, the configurations of the transfer substrate 441 and the reverse transfer substrate 442 are the same as those of the transfer substrate 1, and each electrode of the transfer substrate 441 and the reverse transfer substrate 442 is provided. The configuration of the drive circuit that gives the drive waveform to the toner is not shown, but is the same as that described in each embodiment of the developing device.
With this configuration, it is possible to form a high-quality image by developing with high development quality with less scattered toner.

  Next, a third embodiment of an image forming apparatus provided with a process cartridge according to the present invention will be briefly described with reference to FIGS. 30 and 31. FIG. 30 is a schematic configuration diagram of the image forming apparatus, and FIG. 31 is a schematic configuration diagram of a process cartridge constituting the image forming apparatus.

  The image forming apparatus 500 is an example of a laser printer that forms a full color image with four colors of magenta (M), cyan (C), yellow (Y), and black (Bk), and corresponds to an image signal for each color. Four optical writing devices 501M, 501C, 501Y, and 501Bk (hereinafter also collectively referred to as “optical writing device 501”) that emit laser beams, and four process cartridges 502M, 502C, 502Y, and 502Bk for image formation (in the drawing) , 502B, and a paper feed cassette 503 that stores recording paper onto which an image is transferred, a paper feed roller 504 that feeds recording paper from the paper feed cassette 503, and transports the recording paper at a predetermined timing. Registration rollers 505, a transfer belt 506 for conveying recording paper to the transfer section of each process cartridge, The image forming apparatus includes a fixing device 509 including a fixing belt 507 and a pressure roller 508 for fixing an image transferred onto a sheet, and a discharge roller 510 that discharges a fixed recording sheet to a discharge tray 511. Yes.

  The four process cartridges 502M, 502C, 502Y, and 502Bk have the same configuration (hereinafter also collectively referred to as “process cartridge 502”). As shown in FIG. 31, each process cartridge 502 is an image carrier in the case. A drum-shaped photoconductor 521, a charging roller 522, a developing device 523 according to the present invention, a cleaning blade 524, and the like are integrally provided so as to be detachable from the image forming apparatus main body. By providing the developing device 523 in the detachable process cartridge 502, it is possible to improve maintenance and to easily replace the developing device 523 with another device.

  Further, in the developing device 523, a toner supply roller 525, a charging roller 526, a transport substrate 1, a toner feeding substrate 527 to the transport substrate 1, and a toner return roller 528 for returning the collected toner are provided. It is stored. Further, a slit 530 is provided on the back side of the process cartridge 502 as a window through which the laser beam from the optical writing device 501 is incident.

  Each of the optical writing devices 501M, 501C, 501Y, and 501Bk includes a semiconductor laser, a collimator lens, an optical deflector such as a polygon mirror, a scanning imaging optical system, and the like, and a host (image processing device) such as a personal computer outside the device. ), A laser beam modulated according to the image data for each color is input, scanned on the photosensitive member 521 of each process cartridge 502M, 502C, 502Y, 502Bk, and an electrostatic charge image (electrostatic latent image). Write.

  When the image formation is started, the photosensitive members 521 of the process cartridges 502M, 502C, 502Y, and 502Bk are uniformly charged by the charging roller 522, and the optical writing devices 501M, 501C, 501Y, and 501Bk respond to image data. The laser beam is irradiated to form an electrostatic latent image of each color on each photoconductor.

  The electrostatic latent image formed on the photosensitive member 521 is developed with each color toner and visualized by EH development by the transport substrate 1 of the developing device 523. Further, the toner that has not been developed is transported by the transport substrate 1 and returned to the inlet side of the toner feeding substrate 527 by the toner return roller 528. In this way, by performing development with the developing device according to the present invention, a high-quality image can be formed as described above.

  On the other hand, as shown in FIG. 30, the recording paper in the supply cassette 503 is fed by the supply roller 504 in synchronization with the image formation of each color of the process cartridges 502Bk, 502Y, 502C, and 502M. It is conveyed toward the transfer belt 506 at the timing. Then, the recording paper is carried on the transfer belt 506 and is sequentially conveyed toward the photosensitive members 521 of the four process cartridges 502Bk, 502Y, 502C, and 502M, and toners of Bk, Y, C, and M colors on the photosensitive members. Images are transferred one after the other. The recording sheet on which the four color toner images are transferred is conveyed to the fixing device 509, where the color image composed of the four color toner images is fixed, and is discharged onto the discharge tray 511.

  Next, a fourth embodiment of the image forming apparatus according to the present invention including the process cartridge according to the present invention will be briefly described with reference to FIGS. 32 and 33. FIG. 32 is a schematic configuration diagram of the image forming apparatus, and FIG. 33 is a schematic configuration diagram of a process cartridge constituting the image forming apparatus.

  In this image forming apparatus, process cartridges 560Y, 560M, 560C, and 560Bk (hereinafter also collectively referred to as “process cartridges 560”) of respective colors are juxtaposed along a transfer belt (image carrier) 551 that extends horizontally. This is a tandem color image forming apparatus. The process cartridges 560 have been described in the order of yellow, magenta, cyan, and black, but are not specified in this order, and may be arranged in any order.

  The process cartridge 560 processes a plurality of components such as the latent image carrier 561, the charging unit 562, the developing unit 563 including the toner conveying member (conveying substrate) 1 according to the present invention, and the cleaning device 564. The cartridge is integrally connected as a cartridge, and the process cartridge is detachable from a main body of an image forming apparatus such as a copying machine or a printer.

  Usually, since a color image forming apparatus has a plurality of image forming units, the apparatus becomes large. Further, when each unit such as the developing device, cleaning, charging, etc. fails individually or it is time to replace it due to its life, the apparatus is complicated and it takes much time to replace the unit.

  In view of this, a compact and highly durable color image forming apparatus that can be replaced by the user can be provided by integrally combining at least the components of the image carrier and the developing means as the process cartridge 560. .

  Here, the developing toner on the image carrier developed by the process cartridges 560Y, 560M, 560C, and 560Bk for each color is sequentially transferred to a transfer belt 551 to which a horizontally extending transfer voltage is applied.

  In this way, yellow, magenta, cyan, and black images are formed, transferred onto the transfer belt 551 in a multiple manner, and transferred onto the transfer material 553 by the transfer unit 552. The multiple toner images on the transfer material 553 are fixed by a fixing device (not shown).

  Each of the image forming apparatuses described in the above embodiments includes a developing device including the electrostatic conveyance device according to the present invention. Therefore, the apparatus can be reduced in size and cost, and there is no toner scattering. Image quality can be improved.

  In the above-described embodiment, toner is described as an example of powder, but the present invention can be similarly applied to an apparatus for conveying powder other than toner. In addition, although the drive signal applied to the transport electrode has been described using three phases as an example, it may be four phases, six phases, or the like.

1 is a schematic configuration diagram illustrating a first embodiment of a developing device according to the present invention. It is another schematic block diagram in 1st Embodiment of the developing device which concerns on this invention. It is a schematic diagram which shows the apparatus structure which measures the dynamic resistance DR of the magnetic particle in this invention. FIG. 6 is a schematic diagram ((a), (b)) showing a configuration in which the direction of electric field for toner conveyance is divided into the direction of the development region (A1) and the opposite direction in the nip region (A2) in the present invention. It is a schematic block diagram explaining 2nd Embodiment of the developing device which concerns on this invention. 6 is a graph showing the relationship between the amount of addition obtained from Equation (1) for calculating the coverage of an additive covering the surface of a toner base and the coverage. 6 is a graph showing the relationship between the coverage of an additive and the degree of toner sticking. FIG. 5 is a schematic configuration diagram for explaining toner conveyance in a developing region and a region before and after the toner conveying member in the developing device of the present invention in a substrate shape. FIG. 9 is a plan development view for explaining the configuration of the transfer substrate 1 of FIG. 8. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which follows the BB line of FIG. It is sectional drawing which follows the CC line of FIG. It is sectional drawing which follows the DD line | wire of FIG. It is a schematic diagram explaining an example of the drive waveform provided to the conveyance board | substrate in this invention. FIG. 4 is a conceptual diagram for explaining toner conveyance and hopping in the present invention. FIG. 3 is a conceptual diagram for specifically explaining toner conveyance and hopping in the present invention. It is a block diagram which shows an example of the drive circuit of FIG. It is a schematic diagram explaining an example of the drive waveform (carrier voltage and collection | recovery carrier voltage pattern) formed by the drive circuit. 6 is a schematic diagram illustrating an example of a drive waveform (hopping voltage pattern) formed by the drive circuit 2. FIG. FIG. 6 is a schematic diagram for explaining another example of a drive waveform (hopping voltage pattern) formed by the drive circuit 2; FIG. 6 is a schematic diagram for explaining appropriate conditions for the electrode width and electrode interval of the toner conveying member in the present invention. In FIG. 21, it is a graph which shows the relationship between an electrode width and the electric field (X direction) of a 0V electrode end. In FIG. 21, it is a graph which shows the relationship between an electrode width and the electric field (Y direction) of a 0V electrode end. In FIG. 21, it is a graph which shows the relationship between the film thickness of a surface protective layer, and electric field strength. It is the schematic diagram which showed the strength of the electrolytic strength which acts on the hopping of the electrode surface in FIG. 21 with the relationship with the film thickness (5 micrometers) of a surface protective layer. It is the schematic diagram which showed the strength of the electrolysis intensity | strength which acts on the hopping of the electrode surface in FIG. 21 with the film thickness (30 micrometers) of the surface protective layer. 1 is a schematic configuration diagram illustrating a first embodiment of an image forming apparatus according to the present invention. It is a schematic block diagram explaining 2nd Embodiment of the image forming apparatus which concerns on this invention. It is a principal part enlarged view of the image development apparatus 416 shown in FIG. It is a schematic block diagram explaining 3rd Embodiment of the image forming apparatus which concerns on this invention. FIG. 31 is a schematic configuration diagram of a process cartridge constituting the image forming apparatus of FIG. 30. It is a schematic block diagram explaining 4th Embodiment of the image forming apparatus which concerns on this invention. FIG. 33 is a schematic configuration diagram of a process cartridge constituting the image forming apparatus of FIG. 32.

Explanation of symbols

T toner A1 development area A2 toner supply nip area (nip area)
DESCRIPTION OF SYMBOLS 1 Conveyance board 2 Drive circuit 10 Latent image carrier (photoreceptor)
11 Conveyance area 12 Development area 13 Collection area 31 Latent image carrier (photoreceptor)
34 Developing Device 41 Casing 42 Toner Conveying Member (Conveying Member)
43 Developer supply section (magnetic brush roller)
46 Regulating blade 47 Magnet member 48 Sleeve 49 Power supply (B2)
50 Power supply (B1)
62 Developer 60 Non-magnetic toner (toner)
61 Magnetic carrier (magnetic particles)
101 Base substrate (support substrate)
102 (102a, 102b, 102c) Electrode 103 Surface protective layer 105a, 105b, 105c Common electrode 105a1, 105b1, 105c1 Common electrode 105a2, 105b2, 105c2 Common electrode 105a3, 105b3, 105c3 Common electrode 301 Latent image carrier (photosensitive drum) )
302 Base 303 Photoconductor Layer 305 Charging Device 306 Exposure Unit 316 Development Device 331a, 331b Charging Brush 332 Toner Tank 341 Conveying Substrate 342 Reverse Conveying Substrate 401 Photosensitive Drum 408 Scanning Optical System 415 Charging Device 416 Developing Device 431 Toner Hopper 432 Agitator 433 Toner box unit 434 Charging roller 435 Doctor blade 441 Conveying substrate 442 Reverse feeding substrate 521 Photoconductor 522 Charging roller 523 Developing device 524 Cleaning blade 525 Toner supply roller 526 Charging roller 527 Toner feeding substrate 528 Toner return roller 551 Transfer belt (image carrier) body)
560Y, 560M, 560C, 560Bk Process cartridge 561 Latent image carrier 562 Charging means 563 Developing means 564 Cleaning device

Claims (14)

A developer supply member that holds the developer on the surface and transports the developer; and a toner transport member that transports the toner supplied from the developer supply member to the development region (A1) facing the latent image carrier; A developing device that develops the toner by attaching toner to the latent image on the latent image carrier in A1,
The developer supply member and the toner conveying member are arranged to face each other via a nip region (A2) where the developer supply member supplies toner,
The developer supply member is connected to a power supply (B1) for forming a toner supply electric field,
The toner transport member includes a plurality of electrodes and is connected to a power source (B2) that forms a transport electric field on the electrodes.
When transporting the toner supplied from the developer supply member to the toner transport member by applying a bias of the power supply (B1),
By applying a bias of the power source (B2), the direction of the toner electric field is divided at a predetermined position of the electrode located in the nip area (A2), and one of the toner is directed toward the development area (A1). A developing device characterized in that the other is opposite to A1.   The developing device according to claim 1, wherein the toner conveying member is a member having a cylindrical shape, a belt shape, or a substrate shape.   2. The developing device according to claim 1, wherein a toner transport direction to the development area (A1) by the toner transport member is opposite to a developer transport direction by the developer supply member.   The boundary at a predetermined position of an electrode located in a nip region (A2) that divides the direction of electric field of toner conveyance by applying a bias of the power source (B2) is variable. Development device.   The developer is a two-component developer composed of a magnetic carrier and a non-magnetic toner. The toner has an additive coated on the surface of the toner base, and the coverage of the additive with respect to the surface area of the toner base is 50% or more. The developing device according to claim 1, wherein the developing device is provided. A developer supply member that holds the developer on the surface and transports the developer; and a toner transport member that transports the toner supplied from the developer supply member to the development region (A1) facing the latent image carrier; A developing device that develops the toner by attaching toner to the latent image on the latent image carrier in A1,
The developer supply member and the toner conveying member are disposed to face each other via a nip region (A2) where the developer supplying member supplies toner, and one end of the toner conveying member is in the nip region (A2). Arranged,
The developer supply member is connected to a power supply (B1) for forming a toner supply electric field,
The toner transport member includes a plurality of electrodes and is connected to a power source (B2) that forms a transport electric field on the electrodes.
When transporting the toner supplied from the developer supply member to the toner transport member by applying a bias of the power supply (B1),
By applying a bias of the power source (B2), a toner conveying electric field direction is formed using one end of the toner conveying member disposed in the nip area (A2) as a conveying start point, and the toner moves toward the developing area (A1). A developing device configured as described above.   The developing device according to claim 6, wherein the toner conveying member is a member having a cylindrical shape, a belt shape, or a substrate shape.   The developing device according to claim 6, wherein a toner transport direction by the toner transport member and a developer transport direction by the developer supply member are opposite to each other.   The developer is a two-component developer composed of a magnetic carrier and a non-magnetic toner. The toner has an additive coated on the surface of the toner base, and the coverage of the additive with respect to the surface area of the toner base is 50% or more. The developing device according to claim 6, wherein the developing device is provided.   An image forming apparatus comprising the developing device according to claim 1.   A process cartridge comprising: at least one of a latent image carrier, a charging unit, and a cleaning unit in an electrophotographic process, and the developing device according to claim 1 integrally held therein.   An image forming apparatus comprising the process cartridge according to claim 11.   A developing method comprising: developing with a developing device according to any one of claims 1 to 9 by attaching toner to a latent image on a latent image carrier. An image forming method using the developing method according to claim 13.

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