JP2002287495A - Electrostatic carrying device, developing device, image forming device and classification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that the electrified amount of carried powder is fluctuated. SOLUTION: The carrying base plate 41 is provided with a perpendicular carrying part 41A carrying electrified toner supplied from an electrifying roller 34 and an electrifying member 35 in a perpendicular direction and an inclined carrying part 41B succeeding the perpendicular carrying part 41A and inclined within a range from perpendicular to 180 degrees to a carrying surface side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic conveying device, an image forming device, a developing device, and a classifying device.

[0002]

2. Description of the Related Art As an image forming apparatus such as a copying machine, a printer, and a facsimile, a latent image is formed on a latent image carrier using an electrophotographic process, and a developer (hereinafter, referred to as "toner") is formed on the latent image. In some cases, an image is formed by attaching and developing a visible image to form a visible image, and transferring this toner image to a recording medium (including an intermediate transfer member).

In such an image forming apparatus, as a developing device for developing a latent image, conventionally, a toner stirred in the developing device is carried on the surface of a developing roller which is a developer carrying member, and the developing roller is rotated. The latent image carrier is conveyed 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 is completed, the toner not transferred to the latent image carrier is rotated by a developing roller. There is known an image forming apparatus which collects the toner, newly agitates and charges the toner, carries the toner again on the developing roller, and conveys the toner.

Further, as a developing device, Japanese Patent Application Laid-Open No.
As described in JP-A-9615, toner is conveyed on the surface of the developing roller using electrostatic force, and toner is separated from the surface of the developing roller by suction force generated between the developing roller and the latent image carrier. The toner is made to adhere to the latent image carrier by using a toner that adheres to the body surface, or a transport substrate that transports the toner by electrostatic force, as described in JP-A-59-181375. In some cases, the toner is transported to a position, and the toner is separated from the transport surface by suction force generated between the latent image bearing member and the toner adhered to the surface of the latent image bearing member.

Further, as a powder conveying device for conveying powder such as toner, there is a device for conveying using a space traveling wave electric field as described in Japanese Patent Application Laid-Open No. 7-267363. This is because by applying a driving voltage to the electrode, a spatial traveling wave electric field is formed around the electrode, and a repulsive force and a driving force act on the powder charged by the traveling wave electric field,
The powder is transported in the direction of electric field movement. As a classifier for classifying powders such as toner using the space traveling wave electric field, for example, as described in Japanese Patent Application Laid-Open No. 8-149598, a classifier is operated by applying electrostatic force, gravity, centrifugal force and the like. Sorting) has been proposed.

[0006]

However, in an image forming apparatus provided with a developing device for applying toner to a latent image carrier using a conventional developing roller, when two-component development is used, the developer is agitated. -Since the transfer is performed, the mechanism becomes complicated, the size increases, and the driving energy required for stirring and the like tends to increase. In addition, when a one-component developer is used, the contact charging member is strongly pressed against the developing roller or rotated with a speed difference in order to charge the toner, and the toner is fixed and the roller is worn. The problem is that the reliability is reduced and the service life is shortened.

In the case of a developing roller for two-component development,
A developer consisting of a mixture of carrier and toner, which are magnetic particles, forms a magnetic brush on the outer periphery of the developing roller, and the toner attached to the magnetic brush applies a bias applied to the developing roller and a charge pattern on the surface of the latent image carrier. Is moved in the direction of the latent image carrier in accordance with the electric field formed by the developing device, and development is performed.

At this time, a portion where the toner is consumed by the development from the magnetic brush on the developing roller and a portion where the toner is not consumed occur, and when the toner is supplied again to the portion, regardless of the toner consuming / non-consuming portion. Since the toner is newly supplied, after the toner is supplied, the history of the image remains on the magnetic brush, resulting in uneven toner density.
This density unevenness affects the subsequent development, and tends to result in an image in which an afterimage is superimposed, resulting in a problem that the image quality is reduced.

Further, in the conventional developing device, it is limited to control the average value of the amount of toner supplied to the developing roller, and the amount of charge greatly varies depending on the environment and use conditions. Also, there is a problem that image quality is deteriorated.

The present invention has been made in view of the above points, and uses a TPM (Toner-Phase-Match) electrostatic transfer technique to achieve uniform charge amount of powder to be transferred with a simple configuration. Developing apparatus capable of achieving high image quality by uniformizing the charge amount of toner with a simple configuration, an image forming apparatus equipped with the developing apparatus, and a simpler configuration and lower cost. It is another object of the present invention to provide a classifier capable of driving at a low voltage.

[0011]

In order to solve the above-mentioned problems, an electrostatic transfer device according to the present invention comprises a plurality of electrodes for generating an electric field for moving a powder along a transfer surface by electrostatic force. The transfer substrate has a vertical portion or a portion inclined from the vertical to the transfer surface within a range of 180 ° from the vertical.

Here, it is preferable that the transfer substrate is one of a rigid substrate, a flexible substrate, or a combination of a rigid substrate and a flexible substrate. Further, it is preferable that at least a part of the transfer substrate faces a charging unit for charging the powder.

Further, it is preferable that the plurality of electrodes of the transfer substrate are formed in a diffusion shape. In addition, it is preferable that the electrode has an unevenness at the downstream end in the moving direction of the powder, the upstream end in the moving direction, or the downstream and upstream ends in the moving direction. In this case, it is preferable that the unevenness at the end of the electrode is formed in a wavy shape, a substantially triangular shape, or a rectangular shape. Further, it is preferable that the concave and convex pitch becomes narrower stepwise or continuously as the electrode is located on the downstream side in the moving direction of the powder or the electrode is located on the upstream side in the moving direction. Furthermore, one or more electrode groups composed of two or more electrodes in which the uneven pitch gradually narrows stepwise or continuously as the electrode is more downstream in the moving direction, and the uneven pitch is stepwise or continuous as the electrode is more downstream in the moving direction. It is preferable to include one or a plurality of electrode groups composed of two or more electrodes that become wider as a whole.

The width of the electrodes in the moving direction of the powder is 1/3 to 5 times the average particle diameter of the powder, and the interval between the moving directions of the plurality of electrodes is less than the average particle diameter of the powder. 1/2 or more 10
It is preferably at most twice. Further, it has an inorganic or organic surface protective film covering the electrodes, the thickness of the surface protective film is 10 times or less the average particle diameter, and the specific resistance is 10 * E6Ω.
cm or more, and the dielectric constant is preferably ε = 2 or more. In this case, it is preferable to form a structure having a large number of columnar portions on the surface of the surface protective film. It is preferable that the columnar portion has an aspect ratio in the range of 0.3 to 10.

The developing device according to the present invention includes a developing device for attaching toner to the latent image carrier, and any one of the electrostatic transport devices according to the present invention for supplying toner to the developing device by electrostatic transport. Things. Here, it is preferable to include a toner supply unit that supplies toner to the electrostatic transport device.

A developing device according to the present invention is a toner conveying roller having developing means for adhering toner to a latent image carrier, and a plurality of electrodes for generating an electric field for moving the toner by electrostatic force along a peripheral surface. And the toner conveying roller is rotated in the direction opposite to the direction of movement of the toner by electrostatic force.

Here, the width of the plurality of electrodes of the toner conveying roller in the moving direction of the toner is １ ／ to 5 times the average particle diameter of the toner, and the interval of the plurality of electrodes in the moving direction is the average particle diameter of the toner. It is preferably at least の and at most 10 times. Further, the toner transport roller has an inorganic or organic surface protective film covering the electrodes, the thickness of the surface protective film is 10 times or less the average particle diameter, the specific resistance is 10 * E6 Ωcm or more, and the dielectric constant is Is preferably ε = 2 or more.

It is preferable that these developing devices include a toner supply unit for supplying toner to the toner conveying roller. Further, the developing means can be a developing roller. It is preferable to provide a developer pool near this developing roller, and it is also preferable to provide a stirring member for stirring the toner in the developer pool.

The developing device according to the present invention includes developing means for attaching toner to the latent image carrier, and the developing means generates a plurality of electrodes for generating an electric field for moving the toner along the peripheral surface by electrostatic force. The developing roller has a configuration in which the developing roller is rotated in a direction opposite to a moving direction of the toner by electrostatic force.

The width of the plurality of electrodes of the developing roller in the moving direction of the toner is not less than 1/3 and not more than 5 times the average particle diameter of the toner. It is preferable that the diameter is 1/2 or more and 10 times or less. The developing roller has an inorganic or organic surface protective film covering the electrodes, the thickness of the surface protective film is 10 times or less the average particle diameter, the specific resistance is 10 * E6 Ωcm or more, and the dielectric constant is It is preferable that ε = 2 or more. Further, it is preferable that a charging unit for charging the toner is provided, and the charging unit includes a two-component magnetic brush.

An image forming apparatus according to the present invention includes any one of the developing devices according to the present invention.

A classification device according to the present invention includes any one of the electrostatic transfer devices according to the present invention.

The classifier according to the present invention includes a transport roller for transporting the powder along the peripheral surface by electrostatic force, wherein the transport roller is rotated in a direction opposite to a moving direction of the powder by the electrostatic force. It was done.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a first embodiment of an image forming apparatus according to the present invention will be described with reference to FIG.
FIG. 1 is an overall schematic configuration diagram of the image forming apparatus.
The general outline and operation of this image forming apparatus will be described.
The photoconductor drum 1 (for example, an organic photoconductor: OPC) as a latent image carrier is driven to rotate clockwise in FIG. When a document is placed on the contact glass 2 and a print start switch (not shown) is pressed, the document illumination light source 3 and the mirror 4 are pressed.
The scanning optical system 5 including the mirror 6 and the scanning optical system 8 including the mirrors 6 and 7 move to read a document image.

Here, the scanned document image is read as an image signal by an image reading element 10 arranged behind the lens 9, and the read image signal is digitized and processed. Then, a laser diode (LD) is driven by the image-processed signal, and a laser beam from the laser diode is reflected by a polygon mirror 13 and then radiated onto the photosensitive drum 1 via a mirror 14.
The photosensitive drum 1 is uniformly charged by the charging device 15, and an electrostatic latent image is formed on the surface of the photosensitive drum 1 by writing with a laser beam.

The electrostatic latent image on the surface of the photoreceptor drum 1 is visualized with toner adhered thereto by the developing device 16 having the electrostatic transport device according to the present invention. The visual image is the transfer paper (recording medium) 1 fed from the paper feed unit 17A or 17B by the paper feed rollers 18A or 18B.
9 is transferred by corona discharge of the transfer charger 20. The transfer paper 19 to which the visible image has been transferred is separated from the surface of the photosensitive drum 1 by the separation charger 21,
The visible image is conveyed by the conveyance belt 22, passes through the pressure contact portion of the fixing roller pair 23, and is fixed, and is discharged to a discharge tray 24 outside the apparatus.

On the other hand, the toner remaining on the surface of the photosensitive drum 1 after the transfer is removed by the cleaning device 25, and the charge remaining on the surface of the photosensitive drum 1 is erased by the discharging lamp 26.

Next, a developing device 16 according to the present invention provided with the electrostatic transport device according to the present invention in the image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of the developing device.

The developing device 16 includes a toner hopper 31 for storing the toner, an agitator 32 for stirring the toner in the toner hopper 31, and a charging device for charging the toner in the toner hopper 31 and supplying the toner to the toner box 33. A charging unit including a roller 34 and a charging member 35 disposed in contact with the peripheral surface of the charging roller 34; and a static toner according to the present invention for conveying the toner charged by the charging roller 34 and the charging member 35 to the developing roller 37. A transport substrate 41 of the electrotransport device 36, a developing roller 37 for applying toner to the photosensitive drum 1 for development, a thickness regulating member 38 for regulating the thickness of the toner on the surface of the developing roller 37, A developer reservoir 39 provided in the vicinity, a stirring member 40 for stirring the developer stored in the developer reservoir 39, and the like are provided. The developing roller 37 may be either a two-component type or a one-component type.

Next, the electrostatic transfer device 36 according to the present invention in the developing device 16 will be described with reference to FIG. As shown in FIGS. 3 and 4, the transfer substrate 41 of the electrostatic transfer device 36
On the support substrate 51 having substantially the same width as
.. Are arranged at required intervals in a direction intersecting (here, orthogonal to) the transport direction along the transport direction (toner movement direction), and a transport surface is placed thereon. A surface protective film 53 made of an inorganic or organic insulating material to be an insulating transfer surface forming member to be formed is laminated, and a surface coat layer 54 for reducing contact resistance with toner is formed on the surface of the surface protective film 53. It is a film.

Here, as the support substrate 51, an insulating film such as SiO ₂ is formed on a substrate made of an insulating material such as a glass substrate, a resin substrate or a ceramics substrate, or a substrate made of a conductive material such as SUS. In addition, a rigid substrate, a flexible substrate such as a preimide film, or a substrate in which a rigid substrate and a flexible substrate are connected can be used. Here, a flexible substrate is used to freely bend or bend the transfer surface.

The electrode 52 is made of Al, Ni on the support substrate 51.
-A conductive material such as Cr is formed in a thickness of 0.1 to 0.2 [mu] m, and is patterned into an electrode shape using a semiconductor technology such as a photolithography technology. Here, the electrode 52
The width L in the transport direction (toner movement direction) is set to be not less than 1/3 and not more than 5 times the average particle diameter of the toner to be transported. Further, the interval R between the electrodes 52 is set within a range of not less than 1/2 and not more than 10 times the average particle diameter of the toner to be conveyed.

As the surface protective film 53, for example, Si
O ₂ , TiO ₂ , TiO ₄ , SiON, BN, TiN,
It is formed by depositing Ta ₂ O ₅ or the like with a thickness of 0.5 to 1 μm. By using a material having a large relative dielectric constant, particularly a material having a relative dielectric constant of ε = 2 or more, as the surface protective film 53, it is possible to reduce the driving voltage and to reduce the driving recoil of particles (toner). And the transport speed increases. The thickness of the surface protective film 53 is set to be 10 times or less the average particle size of the toner to be conveyed.

The surface coat layer 54 is a film having a function of reducing the contact resistance between the transfer surface and the interface of the charged toner, and is made of, for example, a fluororesin material such as PTFE or PFA.
It is formed by coating with a thickness of about 0.3 μm.

As shown in FIG. 5, the transfer board 41 of the electrostatic transfer device 36 transfers the charged toner supplied from the charging roller 34 and the charging member 35 in the vertical direction (vertical direction). It has a vertical transport section 41A and an inclined transport section 41B which is continuous with the vertical transport section 41A and inclines within a range of 180 degrees from vertical to the transport surface side.

Although the vertical transport section 41A and the inclined transport section 41B are provided here, any one of the vertical transport section 41A and the inclined transport section 41B may be provided. In addition, for example, as shown in FIG. 6, a bent conveyance unit 41C (a part of the bent conveyance unit 41C is also an inclined conveyance unit 41B) can be formed. That is, if the transfer substrate 41 has a transfer surface (including a transfer surface in the vertical direction) inclined in the range of 0 to 180 ° on the transfer surface side in the transfer direction with respect to the surface in the vertical direction, this vertical portion Or 180 from perpendicular to the transport surface side
It will have a sloping portion that is sloping up to a degree.

The transfer surface 41a of the transfer board 41
Has one end facing the charging means for charging the toner constituted by the charging roller 34 and the charging member 35, and the other end facing the peripheral surface of the developing roller 37.

In order to form the transfer board 41 having the inclined transfer section 41B or the bent transfer section 41C, it is most preferable that the support board 51 of the transfer board 41 be a flexible board as described above. From the standpoint of easiness and ease of arrangement, a combination of a flat substrate (rigid substrate) and a flexible substrate is preferable, and a configuration having only a flat substrate may be employed.

Next, a description will be given of toner transport by electrostatic force based on TPM by the electrostatic transport device 36 of the developing device 16 in the image forming apparatus configured as described above with reference to FIGS. First, as shown in FIG. 7, pulse-shaped drive waveforms Va, Vb, and Vc that change between the ground G and the positive voltage + are applied to the electrodes 52 of the transfer board 41 at different timings. At this time, as shown in FIG. 8, the negatively charged toner T is present on the transfer substrate 41, and “G”, “G”, and “+” are respectively indicated by a plurality of continuous electrodes 52 of the transfer substrate 41. , “G”, and “G” are applied, the negatively charged toner T becomes the “+” electrode 52
Located on top.

At the next timing, the plurality of electrodes 52 have "+", "G", "G", "+",
“G” is applied, and a repulsive force acts on the negatively charged toner T with the “G” electrode 52 on the left side in the figure and a suction force acts on the negatively charged toner T with the “+” electrode 52 on the right side. , The negatively charged toner T moves to the “+” electrode 52 side. Further, at the next timing, “G”, “+”, “G”, “G”, “+” are respectively applied to the plurality of electrodes 52 as shown in FIG. And the attraction force, respectively, the negatively charged toner T is further applied to the “+” electrode 5.
Move to side 2.

As described above, by changing the potential of the drive waveform applied to the electrode 52 and apparently moving the drive waveform, a space traveling wave electric field is generated, so that the negatively charged toner T is placed on the “+” electrode 52 side. Therefore, the negatively charged toner T is transported along the transport surface 41 a of the transport substrate 41. In the case of positively charged toner, the toner can be conveyed in the same direction as in FIG. 8 by reversing the drive waveform change pattern.

The driving waveforms are "+",
A drive waveform that changes with “0” and “−” can also be used. Further, according to an experiment, the toner is conveyed within a driving frequency range of 1 KHz to 20 KHz as the driving frequency of the pulsed driving waveform, and the driving frequency is 18 KHz to 45 KHz.
It has been confirmed that when the value falls within the range, the phenomenon that the toner is pumped occurs. Therefore, in order to cause the toner inappropriate for development to be separated from the transport electric field by the transport substrate 41 as described later, a phenomenon occurs in which the toner is pumped, and the driving is performed within a range where the toner suitable for development does not depart from the electric field. Preferably, it is a frequency.

Here, the width and spacing of the electrodes 52 on the transfer board 41 will be described with reference to FIGS. As described above (see FIG. 3), the width L of the electrode 52 in the transport direction (toner movement direction) of the transport substrate 41 is determined.
Is 1/3 or more and 5 times or less of the average particle diameter of the toner to be conveyed. Thereby, as shown in FIG.
2 shows the electric field intensity distribution E when the driving waveform is applied, and the distribution of the electric field force on the electrode 52 from the center of the electrode width becomes large.
Receives an electric field attraction on either side and is moved and conveyed.

On the other hand, as shown in FIG. 10, the width L of the electrode 52 'exceeds five times the average particle diameter of the toner to be conveyed.
(15 to 50 times of 0 to 250 μm) and the electric field intensity distribution E ′ when the driving waveform is applied to the electrode 52 ′ is as shown in the figure. Since the distribution deviation is small, the toner in the center of the electrode 52 slightly moves up and down but is not moved and conveyed, and a residual portion TM1 in which the toner remains in a mountain shape is generated. As a result, the toner is not conveyed. When the width L of the electrode 52 'is smaller than 1/3 of the average particle diameter of the toner to be conveyed, the driving voltage for generating the electric field strength necessary for conveying the toner is too high.

The distance R between the electrodes 52 is set to a range of not less than 1/2 and not more than 10 times the average particle diameter of the toner to be conveyed. In order to stably carry the toner, it is necessary that the electric field intensity distribution between the electrodes 52 also has a sufficiently large distribution deviation with respect to the size of the powder at the center between the electrodes. As described above, １ ／ of the average particle diameter of the toner to be conveyed is
By setting the electrode interval R within the range of not less than 10 and not more than 10 times, the electric field intensity distribution E as shown in FIG. 8 is obtained, and the toner between the electrodes has a sufficient electric field attraction to either the left or right. It is received and transported.

On the other hand, the distance R between the electrodes 52 exceeds 10 times the average particle diameter (previously, 250 to 500 μm).
As shown in FIG. 10, the electric field distribution at the center between the electrodes has a small distribution deviation with respect to the size of the toner powder, and the toner at the center between the electrodes is hardly affected by the electric field, Is left in the mountain shape to form a residual portion TM2,
This becomes a barrier to transport, and after the initial fine movement, continuous transport becomes impossible. Further, the distance R between the electrodes 52 is set to 1
If it is less than / 2, a sufficient spatial traveling wave electric field does not act on the toner on the electrode 52, and the moving direction becomes unstable.

The operation of the developing device 16 and the image forming apparatus according to the above configuration will now be described. Toner fed from the toner hopper 31 is frictionally charged between the charging roller 34 and the charging member 35 to form a toner cloud 55.
And supplied to the transfer board 41 of the electrostatic transfer device 36,
As described above, the carrier is sequentially conveyed by the electrostatic force of the spatially traveling wave electric field generated by the carrier substrate 41 and supplied to the developing roller 37.

Here, when the developing roller 37 is a two-component developing roller, a fixed or rotatable magnet body is provided inside a conductive cylinder (sleeve), and the developing roller 37 is provided.
A developer made of a mixture of a carrier, which is a magnetic particle, and a toner forms a magnetic brush on the outer peripheral surface (in the case of this embodiment, a single carrier may be used). The toner transported from the transport substrate 41 of the electrostatic transport device 36 adheres to the magnetic brush, and contacts the photosensitive drum 1 in a state where the thickness is regulated by the thickness regulating member 38 with the rotation of the developing roller 37. Alternatively, the sheet is conveyed to an adjacent area (developing section). Then, the toner moves to the photosensitive drum 1 in accordance with the electric field formed by the bias applied to the developing roller 37 and the charge pattern on the surface of the photosensitive drum 1, and the latent image on the surface of the photosensitive drum 1 is developed.

When the developing roller 37 is a one-component developing roller, the toner moves from the transfer board 41 of the electrostatic transfer device 36 to the peripheral surface of the developing roller 37, and the thickness regulating member is rotated with the rotation of the developing roller 37. The toner is transferred to the photosensitive drum 1 in accordance with the electric field formed by the electric charge pattern and the potential of the developing roller 37 while the thickness is regulated at 38, and the latent image on the surface of the photosensitive drum 1 is moved. Is developed.

When the developing roller 37 is a two-component developing roller, the developer on the downstream side of the developing section once separates from the developing roller 37 and is agitated by the stirring member 40 in the developer collecting section 39.
After being mixed with another developer, the toner adheres again to the developing roller 37 to form a magnetic brush.

As described above, the image forming apparatus and the developing device 16 transport the toner by the electrostatic force by the transport substrate 41 based on the TPM principle, and
7 is supplied with toner. When the charged toner is conveyed by electrostatic force, the charged toner is conveyed based on a transfer frequency depending on a driving frequency of a driving waveform applied to the electrodes of the conveyance substrate and between the electrodes. Therefore, since the toner to be conveyed depends on its charge amount, the toner with a small charge amount or the uncharged toner is not sent together with the transfer and conveyance, and the speed is small or does not move, and the toner is charged to the opposite polarity. The moving toner moves in the opposite direction.

Since the supplied toner is conveyed electrostatically, not by mechanical means, it is suitable for miniaturization with a simple mechanism, no drive energy is required, and the apparatus is reduced in size and cost. be able to. In addition, since the toner charged to the opposite polarity or the toner which is hardly charged is not conveyed in the target direction (direction toward the developing roller) and speed, only the toner having an appropriate charge amount can be used for development. Thus, it is possible to prevent the toner from adhering (fogging) to the background portion of the image and prevent the toner from excessively adhering to lower the sharpness and the gradation reproducibility, thereby improving the image quality.

As shown in FIG. 6 or FIG. 7, the transfer substrate 41 of the electrostatic transfer device 36 in the developing device 16 includes a vertical transfer portion 41A and an inclined transfer portion 41B, or a vertical transfer portion 41A and a bent transfer portion. 41C, the toner charged to the opposite polarity, the toner having a small charge amount, and the uncharged toner are transported when passing through the vertical transport section 41A, the inclined transport section 41B, or the bent transport section 41C. Since the toner is easily separated from the driving electric field of the substrate 41 or is separated from the electric field, it is possible to reliably remove such toner unsuitable for development and prevent the toner from being supplied to the developing roller. Accordingly, it is possible to more reliably prevent the toner from adhering (fogging) to the background portion of the image and the toner from excessively adhering to lower the sharpness and the gradation reproducibility, and further improve the image quality.

Further, by providing a developer reservoir 39 and a stirring member 40 near the developing roller 37, the developer on the downstream side of the developing unit is once separated from the developing roller 37 and is developed in the developer reservoir 39 by another developer. After being mixed with the developer, it adheres again to the developing roller 37 to form a magnetic brush, so that unevenness after image development (remaining image history) almost disappears, and the image quality is further improved. In this case, the stirring member 4 is
By having 0, it is possible to form a uniform film of the charged toner and to prevent the charge deterioration due to the triboelectric charging.

Next, another electrode configuration of the transfer board 41 of the electrostatic transfer device 36 will be described with reference to FIG.
First, the transfer substrate 41 of FIG.
2b, 62c, 62d,... Are arranged at required intervals along the moving direction of the toner. Then, each electrode 62
a, 62b, 62c, 62d (hereinafter simply referred to as "electrode 6
2 ". ) Indicates the end 6 on the downstream side in the toner movement direction.
3a, 63b, 63c, 63d (hereinafter, simply referred to as "ends 63") are formed in a planar shape in a wavy shape and formed in an uneven shape. Here, only four electrodes 62 are shown for convenience of illustration, but the present invention is not limited to this.

The unevenness formed on the end 63 of the electrode 62 is not limited to a planar shape and is not limited to a wavy shape, but may be, for example, a triangular shape or a rectangular shape. Further, the unevenness in the longitudinal direction of the electrode 62 may not be uniform.

The width (maximum width in the moving direction) L of each electrode 62 is set to not less than 1/3 and not more than 5 times the size of the average particle diameter.
The interval R of 2 (the interval from the tip of the wavy end 63 of one electrode to the end of the adjacent electrode) R is set to be not less than 1/2 and not more than 10 times the size of the average particle diameter. It is the same as doing.

The uneven pitch P at the end 63 of each electrode 62 is formed narrower toward the electrode 62 on the downstream side in the moving direction.
That is, in the illustrated example, the uneven pitch P of the end 63a of the electrode 62a that is the most upstream in the moving direction is the widest, and the uneven pitch P of the end 63d of the electrode 62d that is the most downstream in the moving direction is the narrowest. The concavo-convex pitch P of each electrode 62 is narrowed continuously (or stepwise) toward the downstream side in the moving direction.

When a driving waveform is applied to each electrode 62 of the carrier substrate 41 thus configured to generate a spatially traveling wave electric field, a mountain portion (protrusion) of an end 63 of each electrode 62 is formed.
As a result, the electric field strength is concentrated on the electrode 64 (a portion of the electric field distribution is formed), and the toner T is applied to the end 63 of each electrode 62.
Move from the peak portion 64 to the adjacent electrode 62.

As described above, since the uneven pitch P of the electrode 62 is narrowed continuously (or stepwise) toward the downstream side in the moving direction, the toner of the electrode 62a which is the most upstream in the moving direction is Concentrated from the peak portion 64 of the end 63a and moved to the next electrode 62b side, dispersed by this electrode 62b and concentratedly moved to the next electrode 62c side from the peak portion 64 of the end 63b. Then, the light is gradually dispersed (moved) such that the light is dispersed by the electrode 62c and moves intensively from the crest 154 of the end 63c to the next electrode 63d.

As described above, in the transport substrate 41, the electrode 62 is formed in a wavy shape at the electrode end on the downstream side in the toner movement direction, and the electric field force between the electrodes 62 is stronger between the wavy protruding end and the adjacent electrode. The toner is concentrated and transported by multiplying the concentrated electric field strength. Then, the toner moves in the moving direction and the amount in conformity with the wavy pitch, and the wavy pitch between the electrodes and the wavy pitch is temporarily reduced in the toner conveying direction. The distribution of the speed and the amount can be made, and the amount of toner at the end of the transport substrate 41 can be made uniform. As a result, a uniform amount of toner can be supplied to the developing roller 37 in the width direction, and the image quality is further improved.

In the transfer substrate 41 shown in FIG. 12, the electrodes 62a, 62b, 62c, 62d (hereinafter, simply referred to as "electrodes 62") are located on the upstream side in the toner movement direction. Ends 65a, 65b, 65c, 65d ...
(Hereinafter, simply referred to as “end portion 65”) is formed in a planar shape in a wavy shape so as to be uneven. Although only four electrodes 62 are shown here for convenience of illustration, the present invention is not limited to this.

The pitch P of the protrusions and recesses at the end 65 of each electrode 62 is narrower as the electrode 62 is located further downstream in the moving direction.
That is, in the illustrated example, the uneven pitch P of the end 65a of the electrode 62a that is the most upstream in the moving direction is the widest, and the uneven pitch P of the end 65d of the electrode 62d that is the most downstream in the moving direction is the narrowest. The concavo-convex pitch P of each electrode 62 is narrowed continuously (or stepwise) toward the downstream side in the moving direction.

When a driving waveform is applied to each electrode 62 of the transport substrate 41 thus configured to generate a spatially traveling wave electric field, a peak portion (protrusion) of an end 65 of each electrode 62 is formed.
As a result, the electric field intensity is concentrated on the area 56 (a part of the electric field distribution is formed), and the toner T is applied to the end 63 of each electrode 62.
From the edge portion 65 of the end portion 65 of the adjacent electrode 62.

Since the uneven pitch P of the electrode 62 is narrowed continuously (or stepwise) toward the downstream side in the moving direction as described above, the toner of the electrode 62a which is the most upstream in the moving direction is The next electrode 62b is dispersed at the peak portion 56 of the end 65a and moves to the next electrode 62b side, and is dispersed at this electrode 62b and further from the end 63 to the next electrode 6b.
It moves (is conveyed) while gradually dispersing, such as dispersing and moving to the mountain portion 65c of the end 65 of 3c.

As described above, also in this transport substrate 41, the electrode 62 is formed so that the electrode end on the upstream side in the toner movement direction has a wavy shape, and the electric field force between the electrodes 62 causes the wavy protruding end of the electrode adjacent to the electrode. And the toner is dispersed and transported by multiplying the concentrated electric field strength. Then, the toner moves in the moving direction and the amount in conformity with the wavy pitch, and the wavy pitch between the electrodes and the wavy pitch is temporarily reduced in the toner conveying direction. The distribution of the speed and the amount can be made, and the toner amount at the end of the substrate becomes uniform. As a result, a uniform amount of toner can be supplied to the developing roller 37 in the width direction, and the image quality is further improved.

The transport substrate 41 shown in FIG. 13 is a combination of the above-described examples, and the electrodes 62a, 62b, 62c, 62d, 6
2e (hereinafter, simply referred to as “electrode 62”) are end portions 63a, 63b, 63c, downstream of the toner moving direction.
63d, 63e (hereinafter, simply referred to as "end 63") and upstream ends 65a, 65b, 65c, 65.
.., 65e (hereinafter, simply referred to as “ends 65”) are formed in a planar shape in a wavy shape so as to be uneven. Here, only five electrodes 62 are shown for convenience of illustration, but the present invention is not limited to this. In addition, the uneven pitch of the downstream end 63 and the uneven pitch of the upstream end 65 may be different.

Further, the concave / convex pitch P of each of the ends 63 and 65 of each of the electrodes 62 is formed so as to be narrower toward the electrode 62 on the downstream side in the moving direction. That is, in the example shown in the drawing, the pitches P of the irregularities P of the ends 63a and 65a of the electrodes 62a that are the most upstream in the moving direction are the widest, and the ends 63e and 65 of the electrodes 62e that are the most downstream in the moving direction.
e so that each electrode 6
2, the concavo-convex pitch P is continuously (or stepwise) narrowed toward the downstream side in the moving direction.

More specifically, as shown in FIG. 14, the concavities and convexities of two adjacent electrodes 62, 62 are arranged at the same pitch, and the peak 64 of one electrode 62 becomes the valley of the other electrode 62. A region 67 arranged (matching) with (a portion between the mountain portions 66) and two adjacent electrodes 62;
An unevenness 62 is provided at the same pitch, and a peak 68 of one electrode 62 is provided with a region 68 arranged so as to match (mismatch) with the peak of the other electrode 62.

In this case, in the region 67 where the two electrodes 62 are aligned, the distance (interval) between the two electrodes 62 becomes uniform in the longitudinal direction of the electrodes 62 and concentration of the electric field intensity distribution does not occur. Speed is relatively fast. On the other hand, in the region 68 where the two electrodes 62 are mismatched, the distance (interval) between the two electrodes 62 is the shortest at the portion where the mountain portions 64 and 66 face each other, and the electric field intensity distribution is more concentrated. As a result, the toner transport speed becomes relatively slow, but the toner is diffused and mixed. As a result, the uniform toner can be more efficiently supplied to the developing roller 37 in a stable manner.

The transfer substrate 41 shown in FIG.
(Here, composed of ten electrodes 62a to 62j) is substantially radially (diffused) from the upstream side to the downstream side in the moving direction.
It is formed and arranged. The uneven end may be on the upstream side, on the downstream side, or on both sides, but here, the downstream side is shown as an example with unevenness.

With this configuration, the toner is supplied to the most upstream electrode 62a, so that the toner is gradually diffused and advances to the most downstream electrode 62j.
The toner is made uniform at the most downstream electrode 62j. As a result, for example, toner can be supplied from a narrow toner supply unit such as a spot-like or small cloud opening or a charging mechanism unit, and the influence of disturbances such as humidity and atmospheric gas is reduced, and the development device can be renewed. It is possible to further reduce the size.

The transfer substrate 41 shown in FIG. 16 has three electrodes 62a, 62a in which the pitch of the unevenness is gradually or gradually reduced.
b, 63c, and a first electrode group 71 composed of
On the downstream side of the electrode group 71, a second electrode group 7 composed of two electrodes 62d and 62e whose uneven pitch gradually or stepwise increases.
2 are further arranged on the downstream side of the second electrode group 72.
A third electrode group 73 of 62 g is arranged.

In this case, the toner supplied to the electrode 62a is applied to each of the electrodes 62a-62 of the first electrode group 71.
After being dispersed and diffused by being sequentially conveyed at c, the light reaches the electrode 62d of the second electrode group 72, and is then concentrated largely sequentially at the electrodes 62d and 62e of the second electrode group 72 to form the third electrode group. 73, and are dispersed and diffused again sequentially by the electrodes 62f, 62g of the third electrode group 73 again.

By repeating the dispersion and concentration of the toner as described above, the mixing property of the toner is enhanced, and the more uniform toner can be efficiently supplied to the developing roller 37.

Next, the surface protection film 53 of the transfer substrate 41 will be described. As described above, as the surface protective film 53 of the transfer substrate 41, a material having a specific resistance of 10 * E6 Ωcm or more and a dielectric constant of ε = 2 or more is selected. A surface protective film that does not discharge the charge (reduction of charge or no charge by charge injection or charge sweeping) is obtained, and by selecting a material with a dielectric constant of 2 or more, the electric field strength is increased in the lateral direction between the electrodes. And the transport efficiency of the particles (toner) in the horizontal direction is improved.

Here, as shown in FIG. 17, by adding fine powder particles 81 of a ferroelectric material as a dielectric constant improving material to the surface protective film 53, the apparent dielectric constant can be increased. For example, the above-mentioned Ta ₂ O ₅ as a film forming material
Is ε = 23 (bulk = 27-32), but Si
O ₂ and TiO ₄ have ε of about _{2 to} 2.7. Therefore,
As the ferroelectric material powder particles 81, for example, BaTiO
₃ = 250 to 2000 and SiN, BN, by adding LiNb _3, etc., the apparent dielectric constant becomes larger.

That is, by adding (dispersing) the fine powder particles 81 of the ferroelectric material to the surface protective film 53, as shown in an enlarged view of FIG. Polarization occurs in the particles 81, and an electric field between the electrodes 52 acts to concentrate on the fine powder particles 81. Therefore, the lateral electric field strength between the electrodes 52 is increased, and the transport efficiency (the efficiency of supplying the toner to the developing roller 37) can be further improved. Note that FIG.
+ And-in the inside show the polarity of the drive waveform.

Further, as shown in FIG.
The surface protection film 53 is etched to remove the film forming material coated with the ferroelectric material fine powder particles 81, and the ferroelectric material fine powder particles 81 such as inorganic material particles and hard organic dielectric particles are removed. , The contact between the toner T and the surface protective film 53 becomes a point contact and the contact resistance is reduced (the Coulomb force is weakened).
In addition to making it easier to transport the toner T, the vertical transport unit 4
1A, the toner having a small charge amount can be more reliably removed at the inclined conveying portion 41B or the bent portion 41C, and the charge amount of the supplied toner T can be further uniformed.

Further, as shown in FIG. 20, the ferroelectric material fine powder particles 81 are further etched from the state where the surface is exposed, so that a large number of columnar portions 82 having the ferroelectric material fine powder particles 81 at the tips are formed. Formed surface structure (needle structure)
It can also be. In this case, the groove between the columnar portions 82 is smaller than the particle size of the toner T, and the toner T is formed at an interval that does not fall into the groove. By forming the columnar portion 82 in this manner, the initial deformation and repetition can be performed by the elasticity of the columnar portion 82, and the toner T can be more easily transported, and the toner T is charged by the vertical transport portion 41A, the inclined transport portion 41B, the bent portion 41C, or the like. The small amount of toner can be more reliably removed, and the charge amount of the supplied toner T can be further uniformed.

Here, the size (particle size) of the ferroelectric material fine powder particles 81 depends on whether the toner to be conveyed collides with the surface of the ferroelectric material fine powder particles 81 or the ferroelectric material fine powder particles 81. A size that is not trapped in between is required. Therefore, it is preferable that the size of the ferroelectric material fine powder particles 81 be substantially the same as the size of the toner to be conveyed, or within the range of 1/1 to 1/10.

The aspect ratio of the columnar portion 82 (height / height)
Is preferably in the range of 0.3 to 10. If the aspect ratio is smaller than 0.3, the elasticity of the columnar portions 82 is not sufficient, and the effect of improving the transportability by forming the columnar portions 82 cannot be sufficiently obtained. When the aspect ratio is 10
If it is larger than the above, there is a possibility that the repetitive restoring property when the toner is pulled in the moving direction at the time of transport may deteriorate. By setting the aspect ratio to 0.3 to 10, the columnar portion 82 can be repeatedly restored even if the columnar portion 82 is pulled by the toner in the moving direction at the time of conveyance by the elastic force at the time of driving of the charged particles.

Since the powder having the certain charge amount is transferred by transferring the powder on the transfer substrate 41 of the first embodiment, only the powder having the certain charge amount is transferred. A classification device for sorting can also be configured.

Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a schematic explanatory view for explaining a developing device portion of the image forming apparatus according to the present invention. The developing device 116 includes the toner hopper 31 and the charging roller 34 of the developing device 16 described above.
A toner supply unit 121 configured to supply charged toner including a charging member 35 and the like;
The toner transport roller 122 transports the charged toner sent from the toner carrier 21 along the peripheral surface with electrostatic force, the developing roller 37 serving as a developing unit to which the toner is supplied from the toner transport roller 122, and the first embodiment. As in the case of the embodiment, a thickness regulating member 38, a developer reservoir 39, and a stirring member 40 are provided.

Here, on the peripheral surface of the toner transport roller 122, a plurality of electrodes for generating a space traveling wave electric field are arranged along the peripheral surface at a predetermined interval as in the case of the transport substrate 41 described above. That is, as shown in FIG. 22, a large number of electrodes 132, 132, 132,... Are provided on a peripheral surface of a roller (or sleeve) 131 which is a support member having substantially the same width as the drum 1 in the axial direction of the photosensitive drum 1. Are arranged at required intervals as a set of three, and a surface protective film 133 made of an inorganic or organic insulating material to be an insulating transfer surface forming member forming a transfer surface is laminated thereon, and Protective film 1
33, a surface coat layer 134 for reducing contact resistance with toner is formed.

Each electrode 13 of the toner conveying roller 122
For 2, a drive waveform in the direction in which the toner moves (conveys) in the direction of arrow A is applied from a drive circuit (not shown). Then, the toner conveying roller 122 itself is slowly rotated in a direction indicated by an arrow B which is opposite (opposite direction) to a direction of conveying the toner by electrostatic force (direction indicated by an arrow A). Note that the rotation direction of the developing roller 37 is
2, the direction of arrow C is opposite to the direction of movement of the toner (the direction of arrow A) (the toner also moves in the direction of arrow D, which is the same direction), and the rotation of the photosensitive drum 1 The direction is the arrow E direction.

With this configuration, the toner is supplied from the toner supply unit 121 to the toner conveying roller 122. The toner conveying roller 122 has a function of electrostatically conveying the surface, and itself rotates in the direction (the direction indicated by the arrow B) opposite to the direction in which the toner is conveyed (the direction indicated by the arrow A). Therefore, when the toner is supplied to the toner conveying roller 122, the toner moves on the surface thereof toward the developing roller 37 by electrostatic force.

At this time, the uncharged toner does not relatively move with respect to the surface of the toner conveying roller 122, and the toner with a small charge moves toward the developing roller 37 at a small speed with respect to the surface of the toner conveying roller 122. I do. Further, the toner charged to the opposite polarity moves in the opposite direction (the direction of arrow B) with respect to the surface of the toner conveying roller 122.

Here, since the toner supply roller 122 is slowly rotating in the direction (arrow B direction) opposite to the electrostatic transport direction (arrow A) of the toner, the surface movement speed of the toner (positive direction, Only the toner whose speed exceeds the surface movement speed of the roller 122 (in the direction indicated by arrow A) (negative direction, direction indicated by arrow B) is conveyed toward the developing roller 37. Such a toner is a toner having a sufficient charge amount. The threshold value of the toner charge amount to be conveyed can be arbitrarily set according to the rotation speed of the toner conveying roller 122. Further, the toner having a conveying speed lower than the rotation speed of the toner conveying roller 122 is returned to the toner supply unit 121 side and charged without being sent to the developing roller 37.

As a result, only the toner having a very small distribution width of the charged amount is sent to the developing roller 37, so that the charged amount of the toner supplied to the developing roller 37 is made uniform, and the oppositely charged toner or the weakly charged toner is supplied. Fog (phenomenon that toner adheres to the background part of the image) and deterioration of sharpness and gradation reproducibility (phenomenon caused by excessive adhesion of toner) caused by image can be reduced, and image quality improves. .
Further, by controlling the number of rotations (rotational speed) of the toner conveying roller 122, it is possible to select a toner charge distribution suitable for the purpose.

Since the supplied toner is conveyed electrostatically instead of mechanically and supplied to the developing roller in the same manner as in the case of using the above-described conveying substrate, the developing device using the developing roller is used. The configuration is simplified, and the size and cost can be reduced. The description of the developing process when the developing roller 37 is a two-component developing roller and the description of the developing process when the developing roller 37 is a one-component developing roller are the same as those in the first embodiment.

Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a schematic explanatory view for explaining a developing device portion of the image forming apparatus according to the present invention. The developing device 146 is supplied with a toner charging roller 152 serving as a charging unit for forming a two-component magnetic brush for charging the toner supplied from the toner supply unit 151, and the charged toner is supplied from the toner charging roller 152. Drum 1 with electrostatic force
And a thickness regulating member 154 that regulates the thickness of the magnetic brush on the toner charging roller 152.

Here, the toner charging roller 152 has at least one pair of magnets inside a conductive member (sleeve) having a non-magnetic surface, and the magnetic field formed by the magnets causes the development of a magnetic carrier and toner. The agent forms a magnetic brush on the sleeve. The toner supplied to the toner charging roller 152 is charged by contact with the carrier. Further, the toner charging roller 152 and the toner developing roller 153
And a potential difference is provided between them, so that the charged toner is supplied from the toner charging roller 152 to the toner developing roller 153.

The toner developing roller 133 is formed by the second
The configuration is the same as that of the toner supply roller 122 of the embodiment, and a plurality of electrodes for generating a spatial traveling wave electric field are arranged along the peripheral surface.

Then, a drive circuit (not shown) is applied to each electrode of the toner developing roller 153 with a drive waveform in the direction in which the toner moves (conveys) in the direction of arrow H. Then, the toner developing roller 153 itself is slowly rotated in the direction of arrow I which is the opposite direction (the direction opposite to the direction of arrow H) of the toner by electrostatic force (the direction of arrow H). The direction of rotation of the toner charging roller 152 is the direction indicated by the arrow F which is opposite to the direction of movement of the toner on the toner developing roller 153 (the direction indicated by the arrow H).
It will move in the direction. ), The rotation direction of the photosensitive drum 1 is the direction indicated by the arrow E.

With the above configuration, the toner supply unit 1
The toner supplied from 51 to the toner charging roller 152 contacts the carrier in the magnetic brush of the toner charging roller 152 and is charged, and the charged toner is supplied to the toner developing roller 153. At this time, since the toner having an inappropriate charge amount is not transferred to the toner developing roller 153, the charge amount of the toner can be adjusted to some extent at this stage.

Then, the toner supplied to the toner developing roller 153 is conveyed by the electrostatic force on the peripheral surface of the toner developing roller 133 in the direction of arrow H and moves toward the developing section. At this time, the uncharged toner does not relatively move with respect to the surface of the toner developing roller 153, and the toner with a small charge moves toward the developing unit at a small speed with respect to the surface of the toner developing roller 153. Further, the toner charged to the opposite polarity moves in the opposite direction (the direction of arrow I) with respect to the surface of the toner developing roller 153.

Here, since the toner developing roller 153 itself is slowly rotating in the direction (arrow I direction) opposite to the toner conveying direction (arrow H direction), the toner surface movement speed (forward direction, arrow direction) (H direction) exceeds the surface movement speed of the developing roller 153 (negative direction, arrow I direction).
It is conveyed in the direction of the developing section. Such a toner is a toner having a sufficient charge amount. It is possible to arbitrarily set the threshold value of the toner charge amount to be conveyed and the speed of the conveyance by the rotation speed of the toner developing roller 153. Further, the toner having a conveyance speed lower than the rotation speed of the toner developing roller 153 is returned to the toner charging roller 152 side and charged again without being sent to the developing unit.

As a result, only the toner having a very small distribution width of the charge amount is sent to the developing unit and subjected to development, so that the charge amount of the toner supplied to the developing unit is made uniform, and (A phenomenon that toner adheres to the background portion of an image) and a decrease in sharpness and gradation reproducibility (a phenomenon caused by excessive adhesion of toner) caused by low-charged toner and toner. Quality is improved.
Further, by controlling the number of rotations (rotational speed) of the toner developing roller 153, it is possible to select a toner charge distribution suitable for the purpose.

As in the case of using the above-described transfer substrate, the supplied toner is not conveyed mechanically but is transferred electrostatically and supplied to the developing roller. The configuration is simplified, and the size and cost can be reduced.

Further, by providing a two-component magnetic brush as a toner charging roller (toner charging means), the toner transport amount can be uniformly transported at 50 mg / cm / s or more, which has been achieved in the past, and furthermore, It has been confirmed that the toner developing roller that performs electro-transport can also transport 50 mg / cm / s or more.

By rotating the roller in the opposite direction to the toner electrostatic transport direction, like the toner transport roller of the second embodiment and the toner developing roller of the third embodiment,
In order to make the charged amount of toner to be conveyed uniform, for example, a conveyance roller for conveying powder other than toner by electrostatic force is provided, and this conveyance roller is rotated in a direction opposite to the electrostatic conveyance direction. It is also possible to configure a classifier that sorts only the powder having the charge amount.

[0103]

As described above, according to the electrostatic transfer device of the present invention, a transfer substrate having a plurality of electrodes for generating an electric field for moving powder by electrostatic force along a transfer surface is provided. Since the transfer surface of the transfer substrate has a vertical portion or a portion inclined from the vertical to the transfer surface side within a range of 180 °, a powder having a low charge amount, no charge, or reverse charge in the vertical portion or the tilt portion is provided. The body can be eliminated, and the charge amount of the powder to be conveyed can be made uniform.

Here, when the transfer substrate is a rigid substrate, the ease of disposition is enhanced, and when the transfer substrate is a flexible substrate, a flexible inclined portion can be formed. The combination of the rigid substrate and the flexible substrate By doing so, the ease of arrangement and the ease of forming the inclined portion are enhanced.

Further, since at least a part of the transfer substrate faces the charging means for charging the powder, the charged powder can be easily supplied to the transfer substrate.

Further, since the plurality of electrodes of the transfer substrate are formed in a diffusion shape, the powder can be supplied from a small supply portion to achieve uniform diffusion, and external influence on the powder is reduced. be able to.

The electrodes are formed with irregularities at the downstream end in the moving direction of the powder, the upstream end in the moving direction, or the downstream and upstream ends in the moving direction. The concentration of distribution can be caused, the powder to be conveyed can be made uniform, and uniform and efficient conveyance can be performed.

In this case, the unevenness of the end portion of the electrode is formed in a wavy, substantially triangular or rectangular shape, so that the electric field intensity distribution can be easily concentrated. In addition, as the electrode on the downstream side in the moving direction of the powder or the electrode on the upstream side in the moving direction has the uneven pitch gradually or continuously narrowed, the conveyed powder is conveyed while being sequentially dispersed and concentrated. be able to.

Further, one or a plurality of electrode groups composed of two or more electrodes in which the uneven pitch gradually narrows stepwise or continuously toward the downstream electrode in the moving direction, and the uneven pitch increases gradually toward the downstream electrode in the moving direction. By providing one or more electrode groups consisting of two or more electrodes that gradually or continuously widen,
It can be transported while performing uniform diffusion and mixing and uniform dispersion.

The width of the electrodes in the moving direction of the powder is 1/3 to 5 times the average particle diameter of the powder, and the interval of the plurality of electrodes in the moving direction of the powder is smaller than the average particle diameter of the powder. 1/2 or more 10
By setting it to twice or less, the stagnation of the powder is prevented, and the powder can be stably and efficiently conveyed.

Further, an inorganic or organic surface protective film for covering the electrode is provided, and the thickness of the surface protective film is 10 μm of the average particle diameter.
Times or less, and the specific resistance is 10 * E6 Ωcm or more,
When the dielectric constant is ε = 2 or more, the powder can be transported stably and efficiently.

In this case, by forming a structure having a large number of columnar portions on the surface of the surface protective film, it is possible to efficiently transport the powder and to reliably remove the low-charged, uncharged or reverse-charged powder. Thus, the charge amount can be made more uniform. When the aspect ratio of the columnar portion is in the range of 0.3 to 10, stable and efficient transport can be performed.

According to the developing device of the present invention, the developing device for attaching toner to the latent image carrier and the electrostatic transport device of the present invention for supplying toner to the developing device by electrostatic transport are provided. As a result, a low charge amount, no charge, or reverse charge can be eliminated, and only a toner having a uniform charge amount can be used for development, thereby improving image quality. Here, the provision of the toner supply means for supplying the toner to the electrostatic transport device allows the toner having a uniform charge amount to be used for development, thereby improving the sharpness and gradation reproducibility of the image. The image quality is improved, and the size of the apparatus can be reduced.

According to the developing device of the present invention, a developing means for adhering toner to a latent image carrier and a toner having a plurality of electrodes for generating an electric field for moving the toner along the peripheral surface by electrostatic force. Transport roller, and the toner transport roller is rotated in a direction opposite to the direction of movement of the toner by electrostatic force, so that a low charge amount, no charge, or reverse charge can be eliminated, and a uniform charge amount can be obtained. Only the toner can be used for development, and the sharpness and gradation reproducibility of the image can be improved, the image quality can be improved, and the apparatus can be downsized.

Here, the width of the plurality of electrodes of the toner conveying roller in the moving direction of the toner is 1/3 to 5 times the average particle diameter of the toner, and the interval in the moving direction of the plurality of electrodes is the average particle diameter of the toner. When the ratio is not less than 1/2 and not more than 10 times, the toner can be stably conveyed by electrostatic force and supplied to the developing unit. Further, the toner conveying roller has an inorganic or organic surface protective film covering the electrodes, the thickness of the surface protective film is 10 times or less the average particle diameter, and the specific resistance is 10 * E6Ωc.
m and the dielectric constant ε = 2 or more, the toner can be stably conveyed by electrostatic force and supplied to the developing unit.

Since these developing devices are provided with the toner supply means for supplying the toner to the toner conveying roller, the toner can be supplied stably. Further, since the developing means is a developing roller, the developing means can be applied to an image forming apparatus using an existing developing roller as it is. By providing the developer pool near the developing roller, a toner re-adding developing roller having no image transfer history can be secured. Further, by providing a stirring member for stirring the toner in the developer pool, it is possible to form a uniform film in the developer pool and prevent charge deterioration due to frictional charging.

According to the developing device of the present invention, there is provided a developing means for adhering toner to the latent image carrier, and this developing means generates a plurality of electric fields for moving the toner along the peripheral surface by electrostatic force. Since the developing roller has a configuration in which the developing roller is rotated in the direction opposite to the direction of movement of the toner by electrostatic force, a low charge amount, no charge, or reverse charge can be eliminated, Only toner having a uniform charge amount can be used for development, sharpness and gradation reproducibility of an image are improved, image quality is improved, and the apparatus can be downsized.

Here, the width of the plurality of electrodes of the developing roller in the moving direction of the toner is １ ／ to 5 times the average particle diameter of the toner, and the interval of the plurality of electrodes in the moving direction of the toner is the average particle size of the toner. When the diameter is not less than 倍 and not more than 10 times, the toner can be stably conveyed. The developing roller has an inorganic or organic surface protective film covering the electrodes, the thickness of the surface protective film is 10 times or less the average particle diameter, the specific resistance is 10 * E6 Ωcm or more, and the dielectric constant is When ε = 2 or more, the toner can be stably conveyed. Further, the image forming apparatus has a charging unit for charging the toner, and the charging unit includes the two-component magnetic brush, whereby the sharpness and gradation reproducibility of an image can be improved.

According to the image forming apparatus of the present invention, since any of the developing devices of the present invention is provided, the sharpness and gradation reproducibility of the image are improved, and the image quality is improved. The size can be reduced.

According to the classification device of the present invention, since any of the electrostatic transfer devices of the present invention is provided, only a powder having a uniform charge amount can be selected with a simple configuration.

According to the classification device of the present invention, there is provided a transport roller for transporting the powder by electrostatic force along the peripheral surface, and the transport roller is rotated in the direction opposite to the moving direction of the powder by the electrostatic force. With this configuration, it is possible to select only powder having a uniform charge amount with a simple configuration.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a developing device portion of the image forming apparatus.

FIG. 3 is an explanatory sectional view of a transfer substrate of the electrostatic transfer device according to the present invention of the developing device.

FIG. 4 is an explanatory top view of the transfer board.

FIG. 5 is an explanatory view for explaining an arrangement of the transfer board.

FIG. 6 is an explanatory view illustrating another example of the arrangement of the transfer substrate.

FIG. 7 is an explanatory diagram for explaining a drive waveform applied to an electrode of the transfer substrate.

FIG. 8 is an explanatory diagram for explaining the principle of toner transfer by the transfer substrate;

FIG. 9 is an explanatory diagram for explaining an operation of an electrode width and an electrode interval of the transfer substrate.

FIG. 10 is an explanatory diagram illustrating toner accumulation in a comparative example in which the toner is compared with the transfer substrate.

FIG. 11 is an explanatory plan view illustrating another first example of the electrode configuration of the transfer substrate.

FIG. 12 is an explanatory plan view illustrating another second example of the electrode configuration of the transfer substrate.

FIG. 13 is an explanatory plan view illustrating another third example of the electrode configuration of the transfer substrate.

FIG. 14 is an explanatory plan view illustrating details of the electrode arrangement of the third example;

FIG. 15 is an explanatory plan view illustrating another fourth example of the electrode configuration of the transfer substrate.

FIG. 16 is an explanatory plan view illustrating another fifth example of the electrode configuration of the transfer substrate.

FIG. 17 is an explanatory plan view illustrating another first example of the surface protective layer of the transfer substrate.

FIG. 18 is an explanatory view serving to explain the operation of the first example;

FIG. 19 is an explanatory plan view illustrating another second example of the surface protective layer of the transfer substrate.

FIG. 20 is an explanatory plan view illustrating another third example of the surface protective layer of the transfer substrate.

FIG. 21 is a schematic explanatory view of a developing device portion illustrating a second embodiment of the image forming apparatus according to the invention.

FIG. 22 is an explanatory diagram for describing a toner conveying roller of the developing device.

FIG. 23 is a schematic explanatory view of a developing device for explaining a third embodiment of the image forming apparatus according to the invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum (latent image carrier), 5 and 8 ... Scanning optical system, 13 ... Polygon mirror, 15 ... Charging device, 16 ... Developing device, 17A, 17B ... Feeding unit, 20 ... Transfer charger, 21 ... Separation charger, 23: fixing roller pair, 3
6 electrostatic transport device, 37 developing roller, 39 developer reservoir, 40 stirring member, 41 transport substrate, 41 vertical transport, 41B inclined transport, 41C bent transport, 5
2. Electrodes, 53: Surface protective layer, 116: Developing device, 12
DESCRIPTION OF SYMBOLS 1 ... Toner supply means, 122 ... Toner conveyance roller, 14
6: developing device, 151: toner supply unit, 152: toner supply roller, 153: toner developing roller.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyoshi Sakai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Yutaka Ebi 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor Takeshi Takemoto 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Company (reference) 2H077 AC04 AC13 AD06 AE02 AE06 EA01 EA11 FA12 FA16

Claims (28)

[Claims] 1. An electrostatic transport device for transporting powder by electrostatic force, comprising: a transport substrate having a plurality of electrodes for generating an electric field for moving the powder along the transport surface with electrostatic force; The electrostatic transfer device according to claim 1, wherein the transfer surface of the transfer substrate has a vertical portion or a portion inclined from the vertical to the transfer surface side within a range of 180 °. 2. The electrostatic transfer device according to claim 1, wherein the transfer substrate is one of a rigid substrate, a flexible substrate, and a combination of a rigid substrate and a flexible substrate. . 3. The electrostatic transfer device according to claim 1, wherein at least a part of the transfer substrate faces a charging unit that charges the powder. 4. The electrostatic transfer device according to claim 1, wherein the plurality of electrodes of the transfer substrate are formed and arranged in a diffused shape. 5. The electrostatic transport device according to claim 1, wherein the electrode is an end portion on the downstream side in the moving direction of the powder, an end portion on the upstream side in the moving direction, or the downstream side and the upstream side in the moving direction. An electrostatic transport device characterized in that each end on the side is formed in an uneven shape. 6. The electrostatic transfer device according to claim 5, wherein the unevenness at the end of the electrode is formed in a wave shape, a substantially triangular shape, or a rectangular shape. 7. The electrostatic transport device according to claim 5, wherein the pitch of the concavo-convex shape decreases stepwise or continuously toward the downstream electrode or the upstream electrode in the movement direction of the powder. An electrostatic transfer device characterized by the above-mentioned. 8. The electrostatic transport device according to claim 5, wherein one or a plurality of electrode groups including two or more electrodes in which the uneven pitch gradually narrows stepwise or continuously toward the downstream side in the moving direction. And two or more electrodes in which the uneven pitch gradually increases stepwise or continuously toward the downstream electrode in the moving direction.
Alternatively, an electrostatic transport device comprising a plurality of electrode groups. 9. The electrostatic transport device according to claim 1, wherein the width of the electrode in the moving direction is not less than 1/3 and not more than 5 times the average particle diameter of the powder. The distance between the electrodes in the moving direction is 1/2 to 10 times the average particle diameter of the powder. 10. The electrostatic transport device according to claim 1, further comprising an inorganic or organic surface protective film covering the electrode, wherein the thickness of the surface protective film is 10% of the average particle diameter. An electrostatic transport device having a specific resistance of 10 * E6 Ωcm or more and a dielectric constant of ε = 2 or more. 11. The electrostatic transfer device according to claim 10, wherein the surface protection film has a structure having a large number of columnar portions on the surface. 12. The electrostatic transport device according to claim 11, wherein an aspect ratio of the columnar portion is in a range of 0.3 to 10. 13. A developing device for attaching toner to a latent image on a latent image carrier and developing the latent image, and developing means for attaching toner to the latent image carrier, and supplying the toner to the developing device by electrostatic conveyance. A developing device comprising the electrostatic transport device according to claim 1. 14. The developing device according to claim 13, further comprising a toner supply unit that supplies toner to said electrostatic transport device. 15. A developing device for adhering toner to a latent image on a latent image carrier and developing the latent image, and a developing unit for adhering toner to the latent image carrier, and moving the toner along a peripheral surface by electrostatic force. And a toner transport roller having a plurality of electrodes for generating an electric field for causing the toner transport roller to rotate in a direction opposite to the direction of movement of the toner by the electrostatic force. 16. The developing device according to claim 15, wherein the width of the plurality of electrodes of the toner transport roller in the moving direction of the toner is equal to or more than ３ of the average particle diameter of the toner.
And an interval between the plurality of electrodes in the moving direction is not less than 1/2 and not more than 10 times the average particle diameter of the toner. 17. The developing device according to claim 15, wherein the toner transport roller has an inorganic or organic surface protective film covering the electrode, and the thickness of the surface protective film is ten times the average particle diameter. Or less, and the specific resistance is 10 * E6Ωcm
And a dielectric constant of ε = 2 or more. 18. The developing device according to claim 15, further comprising a toner supply unit that supplies toner to said toner transport roller. 19. The developing device according to claim 13, wherein said developing means is a developing roller. 20. The developing device according to claim 19, wherein a developer reservoir is provided near the developing roller. 21. The developing device according to claim 20, further comprising a stirring member for stirring the toner in the developer reservoir. 22. A developing device for attaching toner to a latent image on a latent image carrier and developing the latent image, comprising developing means for attaching toner to the latent image carrier, and the developing unit applies the toner along the peripheral surface. A developing device, comprising: a developing roller having a plurality of electrodes for generating an electric field for moving by electrostatic force, wherein the developing roller is rotated in a direction opposite to a moving direction of the toner by electrostatic force. 23. The developing device according to claim 22, wherein a width of the plurality of electrodes of the developing roller in a moving direction of the toner is not less than １ ／ of an average particle diameter of the toner and not more than 5 times, and A developing device, wherein an interval between electrodes in the moving direction of the toner is not less than の and not more than 10 times the average particle diameter of the toner. 24. The developing device according to claim 22, wherein the developing roller has an inorganic or organic surface protective film covering the electrode, and the thickness of the surface protective film is 10 times or less the average particle diameter. A specific resistance of 10 * E6 Ωcm or more and a dielectric constant of ε = 2 or more. 25. The developing device according to claim 22, further comprising charging means for charging said toner, said charging means comprising a two-component magnetic brush. apparatus. 26. An image forming apparatus according to claim 13, wherein toner is adhered to the latent image carrier to develop a latent image on the latent image carrier to form an image. An image forming apparatus comprising the apparatus. 27. A classifier for classifying a powder, comprising the electrostatic transfer device according to claim 1. 28. A classifier for classifying a powder, comprising a conveying roller for conveying the powder by electrostatic force along a peripheral surface, wherein the conveying roller rotates in a direction opposite to a moving direction of the powder by the electrostatic force. A classification device characterized by being performed.