JP2008145758A - Image forming apparatus - Google Patents

Abstract

In an image forming apparatus in which a plurality of sets of charging devices, image exposure units, and developing devices are arranged on the peripheral surface of an image carrier to form a superimposed toner image on the image carrier, the entire device is maintained while maintaining high image quality. Downsizing.
A plurality of sets of a charging device, an image exposing unit, and a developing device are disposed on the circumferential surface of a photosensitive member, and a superimposed toner image is formed by repeating charging, exposing, and developing a plurality of times on the photosensitive member. In the image forming apparatus to be formed, the developing device 3 includes a toner conveying member 30 that conveys toner to the developing region by a traveling wave electric field generated on the surface, a toner supply unit that supplies toner to the toner conveying member, and a developing region. And a collecting unit that collects the toner from the toner conveying member.
[Selection] Figure 1

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.

The following three methods are known as image forming apparatuses that form full-color images.
(A) A single-color toner image formed on the photosensitive member is transferred by providing the same number of photosensitive members as the colors forming the color image, and a charging device, an image exposure unit, and a developing device arranged around each photosensitive member. A device that creates a color image superimposed on the body. Since this apparatus can form a color image on a transfer member in one pass, it is advantageous for speeding up, but it has a drawback that the volume of the apparatus increases because it requires transport of a plurality of photoconductors and transfer bodies.
(B) An apparatus that includes a charging device, an image exposure unit, and a developing device for each color around one photosensitive member, and rotates the photosensitive member a plurality of times to repeatedly charge, expose, and develop each color to form a color image. Although this apparatus has only one photoreceptor, a charging device, and an image exposure unit, the volume is reduced, but the speed is low and the size of the formed image is limited to the surface area of the photoreceptor or less. is there.
(C) A plurality of sets of charging devices, image exposure units, and developing devices are provided around one photoconductor, and each color is charged, exposed, and developed sequentially within one rotation of the photoconductor to form a color image on the photoconductor. apparatus. This apparatus combines the advantages of the above two methods, that is, high speed and that there is no restriction on the image size and that the apparatus can be miniaturized.

  As a developing device employed in an image forming apparatus, a developing device that carries a developer on the surface of a developing roller that is driven to rotate and conveys the developer to a position facing the photosensitive member is widely known. Here, in the image forming apparatus that sequentially develops one photoconductor using the method (C) to form a color image on the photoconductor, in order to obtain a high-quality image, the previously developed toner image is used. It is necessary to perform non-contact development so as not to disturb. Non-contact development is a so-called jumping development in which toner is transferred from a developing roller to a latent image carrier in a non-contact manner by applying a voltage in which AC is superimposed on DC to the rotationally driven developing roller. Is known (see Patent Document 1 and Patent Document 2).

  On the other hand, in recent years, developing devices that do not use a rotationally driven developing roller have also been proposed. This is a device that performs development by electrostatically transporting toner without the mechanical drive of a toner transport member that transports toner, and utilizes the ETH (Electrostatic Transport & Hopping) phenomenon described in Patent Document 3. Is. The ETH phenomenon is a phenomenon in which the energy of the phase-shifting electric field acting on the powder is converted into mechanical energy and the powder itself dynamically changes. In the image forming apparatus of Patent Document 3, an electrostatic transport member in which a plurality of electrodes are arranged at a predetermined pitch is used as a toner transport member, and a traveling wave electric field generated by applying an n-phase AC voltage to the electrodes, The movement of the charged toner in the direction of the electrostatic conveyance member surface (conveyance) and the movement in the direction perpendicular to the surface of the electrostatic conveyance member (hopping) are performed. As a result, the charged toner is conveyed to the development position. At the development position, the hopped toner is subjected to a force toward the toner conveying member in the non-image portion and a force toward the image carrier in the image portion, and the electrostatic latent image is developed. Such a development method using the ETH phenomenon is called ETH development. Here, the ETH development is extremely difficult to realize with a configuration using a rotationally driven toner conveying member by hopping the toner on the toner conveying member and conveying it to the developing position while eliminating the adhesion force. Highly efficient development can be realized.

Japanese Patent Publication No. 3376199 JP-A-9-329947 JP 2004-198675 A

  The apparatus using the method (C) enables high-speed and small-sized image formation, but requires a space for arranging a plurality of charging devices, image exposure units, and developing devices in one circumference of the photoreceptor. Inevitably, the diameter of the photoconductor is inevitably increased, and there are cases in which miniaturization cannot be sufficiently achieved. In addition, if a plurality of sets of charging devices, image exposure units, and developing devices are arranged in a limited space, the image forming process means may be constrained by each other, which may hinder image quality improvement. .

  In addition, in the case of using the rotation-driven developing roller as the developing device, the developing roller disposed facing the circumferential surface of the photosensitive member has a roller diameter to ensure mechanical accuracy as the image forming size increases. It needs to be bigger. This inevitably increases the diameter of the photoconductor and the image forming apparatus.

  In addition, in a developing device that performs jumping development by applying a voltage in which AC is superimposed on DC to a rotationally driven developing roller, a high voltage power source is required because charging toner must be exchanged with a high voltage. As a result, the size of the apparatus is increased and the cost is increased.

  The present invention has been made in view of the above-described background, and an object of the present invention is to provide a plurality of charging devices, an image exposure unit, and a developing device on the peripheral surface of the image carrier, on the image carrier. Another object of the present invention is to provide an image forming apparatus capable of reducing the size of the entire apparatus while maintaining high image quality.

In order to achieve the above object, according to the first aspect of the present invention, a plurality of sets of charging devices, image exposure units, and developing devices are arranged on the circumferential surface of the image carrier, and the image carrier is charged. In the image forming apparatus in which exposure and development are repeated a plurality of times to form a superimposed toner image on the image carrier, the developing device has a developing region in which the toner is opposed to the image carrier by a traveling wave electric field generated on the surface. A toner conveying member that conveys the toner to the toner conveying member, a toner supplying unit that supplies the toner to the toner conveying member, and a collecting unit that collects the toner that has passed through the developing area from the toner conveying member. It is.
According to a second aspect of the present invention, in the image forming apparatus of the first aspect, a transfer body to which the toner image on the image carrier is transferred while being moved endlessly, and a heating means for heating the toner image on the transfer body. And a pressure member facing the transfer body downstream of the heating means, the toner image transferred onto the transfer body is softened by the heating means, and the softened toner image is transferred to the transfer body The image forming apparatus includes a transfer fixing device that simultaneously fixes and transfers onto a recording medium passing between the body and the pressure member.
According to a third aspect of the present invention, in the image forming apparatus of the second aspect, an intermediate transfer member is provided between the image carrier and the transfer member, and the toner image on the image carrier is transferred to the intermediate transfer member. And transferring to the transfer body.
According to a fourth aspect of the present invention, in the image forming apparatus according to the first, second, or third aspect, the toner conveying member has an elliptical shape or an elliptical shape.
According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third, or fourth aspect, the toner supply unit includes a developer stirring member that stirs the developer composed of the toner and the carrier and frictionally charges the developer stirring member. It has a supply roller that carries and conveys the frictionally charged developer, and a regulating member that thins the developer on the supply roller.
According to a sixth aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, or fifth aspect, the collecting means is a brush roller provided facing the toner conveying member, and the brush roller. It has a flicker in contact with it and a bias applying means for applying a bias to the brush roller.
According to a seventh aspect of the present invention, in the image forming apparatus of the sixth aspect, the collecting means is provided above the toner supplying means.
According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the toner conveying member, the toner supplying means, and the collecting means are arranged in a case and integrally configured. It is.
According to a ninth aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, fifth, sixth, seventh or eighth aspect, at least one location between the developing device and a charging device adjacent to the downstream side. Is provided with a static eliminator.

In the present invention, a developing device using a toner conveying member that conveys toner by a traveling wave electric field is employed, and it is not necessary to rotate the toner conveying member. It will be big. That is, the portion of the toner conveying member that faces the image carrier can be made small in shape, and the peripheral surface space of the image carrier necessary for disposing the developing device can be reduced. Therefore, even if the charging device, the image exposure unit, and the developing device are arranged on the peripheral surface of the image carrier, it is possible to prevent the entire device from becoming large. Furthermore, even when it is necessary to increase the peripheral length of the toner conveying member, it is possible to cope with the toner conveying member with the portion facing the image carrier remaining in a small shape, and the entire apparatus becomes large. You can avoid that. Therefore, a large number of image forming process means can be arranged on the peripheral surface of the image carrier having a small diameter, and the image forming apparatus can be downsized. Further, since the degree of freedom of the shape of the toner conveying member is large, the degree of freedom of arrangement of the toner supply unit and the collecting unit is increased. As a result, it is possible to configure a supply unit capable of stabilizing the characteristics of the supplied toner and a recovery unit with high recovery efficiency, thereby improving the image quality. Furthermore, the degree of freedom of arrangement of the respective image forming process means is increased, and it is easy to avoid that the image quality is deteriorated due to mutually restrictive conditions.
Further, in this developing device, the toner is hopped on the toner conveying member by a traveling wave electric field and development is performed without losing the adhesion force, so that the configuration using the rotationally driven developing roller could not be realized. This makes it possible to achieve highly efficient non-contact development. Therefore, a high-voltage power source such as jumping development using a rotationally driven developing roller is not necessary.
As described above, the space on the peripheral surface of the image carrier necessary for disposing the developing device is reduced, the space shape is freed, and a high-voltage power source for non-contact development is not required. This makes it possible to reduce the size of the device.

  As described above, according to the present invention, in an image forming apparatus in which a plurality of charging devices, an image exposure unit, and a developing device are arranged on the peripheral surface of an image carrier and a superimposed toner image is formed on the image carrier, There is an excellent effect that the entire apparatus can be reduced in size while maintaining the above.

Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus will be described. First, the configuration and operation of the image forming apparatus according to the present embodiment will be described.
FIG. 1 is a schematic configuration diagram of the entire image forming apparatus according to the present embodiment. A photosensitive drum 1 as an image carrier is provided at the center of the main body of the image forming apparatus. Around the photosensitive drum 1, a charging device and a developing device for forming toner images of yellow (Y), magenta (M), cyan (C), and black (Bk) colors are counterclockwise from above. Four sets are arranged around. Further, an exposure device 5 for irradiating the photosensitive drum 1 with laser light is provided on the right side of the device, and a laser for forming an electrostatic latent image of each color at an exposure portion between each charging device and each developing device. Irradiating light. That is, the charging device 2Y for yellow (Y), the exposure unit 3Y, the developing device 4Y, the charging device 2M for magenta (M), the exposure unit 3M, the developing device 4M, the charging device 2C for cyan (C), and the exposure unit. 3C, a developing device 4C, a black (Bk) charging device 2Bk, an exposure unit 3Bk, and a developing device 4Bk are arranged in this order. In addition, a transfer belt device 9 and a cleaning device 14 are provided around the downstream photosensitive drum 1.

  In addition, regarding the charging devices 2Y, M, C, and Bk, the exposure units 3Y, M, C, and Bk, and the developing devices 4Y, M, C, and Bk, the parts having the same configuration and operation are subscripts Y, M, C, and Bk will be omitted for explanation.

  The charging device 2 is a scorotron charger. The organic photosensitive layer of the photosensitive drum 1 is charged by a grid held at a predetermined potential and corona discharge by a discharge wire, and is applied to the surface of the photosensitive drum 1. Various potentials are given.

  The exposure device 5 has an integrated unit configuration that radiates laser light to the photosensitive drum 1 in four locations radially. The exposure device 5 irradiates the exposure unit 4 on the uniformly charged photoreceptor 1 with laser light based on the image data of each color to form an electrostatic latent image of each color. The exposure apparatus may be composed of four units unitized for each color or each LED array.

  The developing device 4 uses a toner conveying member 30 that electrostatically carries and conveys toner without being driven to rotate. Details will be described later.

The transfer belt device 9 includes a transfer belt 13, a driving roller 10 that stretches the transfer belt 13, a driven roller 11, and a transfer roller 12. A transfer roller 12 is disposed inside the transfer belt 13 in a region where the transfer belt 13 is in contact with the circumferential surface of the photosensitive drum 1, and a transfer area in which the toner image on the photosensitive drum 1 is transferred onto a recording sheet carried by the transfer belt 13. Form. The transfer belt 13 is an endless belt. This belt has a volume resistance of 10 ⁸ to 10 ¹² [Ω · cm] and a thickness of 0.5 to 2.0 [mm] made of silicon rubber or urethane rubber, and toner filming prevention. It is a rubber belt having a two-layer structure of a semiconductive surface layer of fluorine coating having a thickness of 5 to 50 [μm]. Instead of the rubber-like substrate, a semiconductive polyester having a thickness of 0.1 to 0.5 [mm], polystyrene, polyethylene, polyethylene terephthalate, or the like can also be used. The transfer belt 13 is provided with a belt cleaning device (not shown) for cleaning the belt surface.

  The cleaning device 14 includes a cleaning blade 15 and a fur brush 16. Only the cleaning blade 15 may be used.

  A fixing device 18 is disposed downstream of the transfer belt device 9 with respect to the conveyance direction of the recording paper. The fixing device 18 includes an endless fixing belt 19, two rollers that support the fixing belt 19, a tension roller 20, and a pressure roller that is in pressure contact with the fixing belt 19.

  Further, at the lower part of the image forming apparatus main body, a paper feed cassette 21 in which recording paper as a transfer material is stored, and a paper feed roller 22 for feeding the recording paper from the paper feed cassette 21 and a feed roller 23 are arranged. A conveyance roller pair 24 and a registration roller pair 25 are provided on the recording paper conveyance path to the transfer belt 13. The recording paper transport path after the fixing device 18 is a paper discharge roller 27 for discharging to a recording paper stack provided on the main body, the reverse roller 28 for a double-sided printing path, and the reverse path to the registration roller 25. Three pairs of conveyance rollers are provided. Further, a manual paper feed unit is provided on the left side of the main body, and a pickup roller 29 and a feed roller for feeding and transporting recording paper are disposed.

Next, the operation of the image forming apparatus having the above configuration will be described.
The original image is temporarily stored as an image signal for each color of Y, M, C, and Bk by reading an image read by an image sensor of an image reading device (not shown) separate from the present device or an image edited by a computer. Is stored and stored. At the start of image recording, the photosensitive drum 1 is rotated counterclockwise by the start of a photosensitive member driving motor (not shown), and at the same time, application of a potential is started by the charging action of the Y charging device 2Y. After the photosensitive drum 1 is applied with an electric potential, exposure 3C based on an electrical signal corresponding to the first color signal, that is, a yellow (Y) image signal is started by the laser light emitted from the exposure device 5 to rotate the drum. By scanning, an electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface. The Y latent image is developed in a non-contact and non-contact manner by the toner conveyed to the portion facing the photosensitive drum 1 by the toner conveying member 30 of the developing device 4Y, and yellow (Y) toner is formed on the photosensitive drum 1. An image is formed.

  Next, the photosensitive drum 1 is given a potential on the yellow (Y) toner image by the charging action of the M charging device 2M, and the second color signal, that is, magenta, is emitted by the laser light emitted from the exposure device 5. Exposure 3M is performed with an electrical signal corresponding to the image signal (M), and an electrostatic latent image corresponding to the magenta (M) image of the original image is formed. The latent image for M is developed by the toner conveying member 30 of the developing device 4M with the toner conveyed to the portion facing the photosensitive drum 1 in a non-contact and non-contact manner, and on the yellow (Y) toner image. The magenta (M) toner images are sequentially superimposed and formed. By the same process, the C charging device 2C, the exposure device 3C by the exposure device 5 and the developing device 4C further generate a cyan (C) toner image corresponding to the third color signal, and the exposure device 3Bk by the charging device 2Bk and the exposure device 5. In addition, a black (Bk) toner image corresponding to the fourth color signal is sequentially overlapped and formed by the developing device 4Bk, and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 1. .

  On the other hand, the recording paper is carried out from the paper feed cassette 21 by the operation of the paper feed roller 22 and the feed roller 23 and conveyed to the registration roller 25, and the transfer belt 13 is synchronized with the conveyance of the color toner image on the photosensitive drum 1. Paper is fed to the transfer area. In the transferred recording sheet, a color toner image is sequentially transferred onto the recording sheet by applying a bias voltage having a polarity opposite to that of the toner by the transfer roller 12 in the transfer area.

  After the transfer, the transfer residual toner on the photosensitive drum 1 is cleaned by the cleaning device 14. For cleaning, first, the residual toner is peeled off from the photosensitive drum 1 by the fur brush 16, and then completely scraped off by the cleaning blade 15 downstream thereof. The cleaned toner is sent by a cleaning screw 17 to a waste toner bottle (not shown).

  Further, when the recording sheet that has received the transfer of the color toner image is electrostatically attached to the transfer belt 13 and conveyed to the drive roller 10, the leading end of the recording sheet is separated from the transfer belt 13 by the curvature and is transferred to the fixing device 18. The sheet is conveyed, nipped and conveyed between the fixing belt 19 and the pressure roller, heated, fused with toner, and then discharged to the apparatus stack unit 26 via the sheet discharge roller 28.

  In the case of duplex printing, the recording paper is conveyed to the reverse roller 28 side and is sent again to the registration roller 25 by the reverse rotation of the reverse roller 28. Then, in synchronization with the color toner image formed on the photosensitive drum 1, it is sent to the nip portion of the transfer belt 13, transferred to the back surface of the recording paper, passes through the fixing device 18 again, and is discharged to the stack portion 26. Is done.

  The developing device 4 of this embodiment will be described in detail. The developing device 4 is an ETH developing type developing device using an ETH phenomenon, and includes a toner conveying member 30 that electrostatically carries and conveys toner without being driven to rotate. The ETH 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. It is a phenomenon that jumps with ingredients. In this specification, when the behavior of the powder on the conveying member in the ETH phenomenon is distinguished and expressed, regarding the movement in the horizontal direction of the substrate, “conveying”, “conveying speed”, “conveying direction”, “conveying” 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 “transport device” and “transport substrate” is synonymous with “transfer”.

  FIG. 3 is a schematic diagram of the vicinity of the facing portion between the toner conveying member 30 and the photosensitive drum 1. The toner conveying member 30 has a plurality of electrodes 102 for generating an electric field for conveying, hopping, and collecting the toner T that is powder. Different drive waveforms Va1 to Vc1 and Va2 to Vc2 of n phase (here, three phases) for generating a required electric field from the drive circuit 106 are applied to each electrode 102 of the toner conveying member 30. The

  Here, the toner conveyance member 30 includes a conveyance region for transferring the toner T to the vicinity of the photosensitive drum 1 and a photosensitive region 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 1. A developing area for forming a toner image by attaching toner T to the latent image of the body drum 1 and an area after passing through the developing area for collecting the toner T on the toner conveying member 30 side (hereinafter referred to as “collecting” It is divided into “regions”).

  In the transport area, the toner T on the toner transport member 30 is transported to the vicinity of the photosensitive drum 1. In the development area, the toner T is directed toward the photosensitive drum 1 for the image portion of the latent image on the photosensitive drum 1, and the toner T is opposite to the photosensitive drum 1 for the non-image portion (toner conveyance). An electric field in the direction toward the member 30 is formed, and the toner T is attached to the latent image for development. In the collection area, the toner T forms an electric field in a direction toward the opposite side (toner conveying member 30 side) from the photosensitive drum 1 with respect to both the image portion and the non-image portion of the latent image. As a result, in the development area, the toner adheres to the latent image on the photosensitive drum 1 to be visualized, and the toner that has not contributed to the development is a collection area on the downstream side in the rotation direction (movement direction) of the photosensitive drum 1. Since the toner is collected on the toner conveying member 30 side, the generation of scattered toner is prevented. The collection area is located downstream of the development area in the moving direction of the photosensitive drum 1, so that the floating toner can be reliably collected.

  Further, the configuration and operation of the toner conveying member 30 will be described in detail. 4 is an explanatory plan view of the toner conveying member 30, FIG. 5 is an explanatory sectional view taken along the line AA in FIG. 4, FIG. 6 is an explanatory sectional view taken along the line BB in FIG. FIG. 8 is a cross-sectional explanatory view taken along the line D-D of FIG. 4. In FIG. 4, the toner conveying member 30 has a predetermined set of three electrodes (conveying electrodes) 102 a, 102 b, 102 c (these are also collectively referred to as “electrodes 102”) on a base substrate (supporting substrate) 101. At intervals, the toner is repeatedly formed and arranged in the direction substantially perpendicular to the toner transfer direction along the toner transfer direction indicated by the arrow in the figure. A surface protective layer 103 made of an inorganic or organic insulating material which is a protective film covering the surface of the electrode 102 and forms a transport surface is laminated thereon. Although the surface protective layer 103 forms a transport surface, a surface layer having excellent compatibility with powder (toner) can be separately 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. 4, the common electrode 105 is indicated as a common electrode 105 a 1, 105 b 1, 105 c 1 in the transport area, a common electrode 105 a 2, 105 b 2, 105 c 2 in the development area, and a common electrode 105 a 3, 105 b 3, 105 c 3 in the recovery area. .

  Here, after the patterns of the common electrodes 105a, 105b, and 105c are formed on the support substrate 101, the interlayer insulating film 107 (which may be either the same material as the surface protective layer 103 or a different material) is formed. After the contact hole 108 is formed in the interlayer insulating film 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 can be formed on the interlayer insulating film. That is, the electrode can have a three-layer structure. Moreover, the interconnection and the interconnection by the contact hole can be mixed in the integral formation.

  Furthermore, 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 31. 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, polyimide A substrate made of a flexible material such as a film can be used.

  The electrode 102 is formed by forming a conductive material such as Al or Ni—Cr on the support substrate 101 in a thickness of 0.1 to 10 [μm], preferably 0.5 to 2.0 [μm]. It is formed by patterning into a required electrode shape using a photolithographic technique or the like. The width L of the plurality of electrodes 102 in the powder traveling direction is 1 to 20 times the average particle diameter of the powder to be moved, and the distance R in the powder traveling direction of the electrodes 102 and 12 is also moved. The average particle size of the body is 1 to 20 times.

  As the surface protective layer 103, for example, SiO2, TiO2, TiO4, SiON, BN, TiN, Ta2O5 and the like are formed to a thickness of 0.5 to 10 [μm], preferably 0.5 to 3 [μm]. 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 toner transport substrate 30 having the above configuration will be described. By applying an n-phase driving waveform to the plurality of electrodes 102 of the toner conveying member 30, a phase shift electric field (traveling wave electric field) is generated by the plurality of electrodes 102, and the charged toner on the toner conveying member 30 is In response to the repulsive force and / or suction force, it moves in the transfer direction including hopping and conveyance.

  For example, with respect to the plurality of electrodes 102 of the toner conveying member 30, as shown in FIG. 9, a three-phase pulse-shaped driving waveform (driving signal) A (changing between the ground G (0 V) and the positive voltage + is shown. The application is performed by shifting the timing of A phase), B (B phase), and C (C phase). At this time, as shown in FIG. 10, the negatively charged toner T is present on the toner conveying member 30, and “G”, as shown in FIG. If “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”, and “+” 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 is generated on the toner conveying member 30, and the negatively charged toner T is moved in the traveling direction of the traveling wave electric field. Move 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.

  This will be specifically described with reference to FIG. 11. As shown in FIG. 11A, the electrodes A to F of the transport substrate 1 are all 0 V (G), and the negatively charged toner T is formed on the transport substrate 1. When “+” is applied to the electrodes A and D as shown in FIG. 5B, the negatively charged toner T is attracted to the electrodes A and D and is applied to the electrodes A and D. Move. 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. Further, 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.

  FIG. 2 is a schematic configuration diagram of the developing device 4 using the toner conveying member 30. 2 shows the developing device for magenta (M) in the image forming apparatus in FIG. The developing device 4 includes a toner conveying member 30 having the above-described configuration that is disposed so as to face the photosensitive drum 1 in a non-contact manner, a supply unit that supplies toner to the toner conveying member 30, and a toner conveying member that has passed through the developing region. And a collecting means for collecting the toner from 30.

  Here, as shown in FIG. 2, the toner conveying member 30 has an oval or elliptical shape. When a plurality of developing devices 4 are arranged on the peripheral surface of the photosensitive drum 1 as in the image forming apparatus of the present embodiment, the area occupied on the surface of the photosensitive drum 1 is reduced by using such a shape. It becomes possible to arrange in space-saving. Further, by changing the length of the ellipse according to the position at which the ellipse is arranged, the supply means and the recovery means can effectively use the space around the photosensitive drum 1, and the degree of freedom of the configuration is widened, so that a high-performance configuration is possible. .

  The supply means carries a developer containing portion 37 for containing the developer, two screws 33 and 34 for agitating and conveying the developer in the developer containing portion 37, and a two-component developer. A supply roller 31 for supplying toner from the component developer to the toner conveying member 30 and a doctor blade 32 for regulating the developer layer thickness on the supply roller 31 are provided. The developer is a two-component developer composed of a nonmagnetic toner and a magnetic carrier. The supply roller 31 includes a magnetic field generating unit in which a magnet is fixed to a rotatable nonmagnetic sleeve, and the surface of the sleeve is disposed to face the toner conveying member 30 in a non-contact manner. The two screws 33 and 34 are arranged in parallel obliquely below the supply roller 31 or in a horizontal position, and convey the developer while stirring the developer in opposite directions parallel to the supply roller 31. To do. The developer accommodating portion 37 is provided with a partition plate 36 that is divided into two chambers for two screws. The back and front of the partition plate 36 are cut out so that the two chambers where the developer is partitioned communicate with each other.

The collecting means includes a brush roller 38 and a flicker 39. The brush roller 38 is formed by planting fine fibers, and is provided downstream of the developing region in the toner transport direction of the toner transport member 30. When the bias voltage is applied, the toner that has not contributed to development is removed from the toner transport member 30. It is electrostatically attracted and separated. The electrical resistance value (volume resistivity) of the fibers of the brush roller 38 is in the range of 10 ² to 10 ¹⁰ [Ω · cm], preferably 10 ² to 10 ⁴ [Ω · cm]. The density of the brush is in the range of 30,000 [lines / inch] to 150,000 [lines / inch], preferably 100,000 [lines / inch] to 130,000 [lines / inch]. In this embodiment, the material of the brush is Toray SA7 (carbon-containing acrylic fiber) (300D / 48F). Other brush materials include Teijin B-TCF (conductive polyester fiber), conductive PET, and conductive nylon fiber. A bias voltage applied to the brush roller 38 has a polarity opposite to that of the bias voltage applied to the toner conveying member 30. In this embodiment, a bias voltage is applied to the brush roller 38 in the range of 0V to + 700V, preferably in the range of + 300V to + 500V. The flicker 39 is composed of a bar protruding inward from an integrated case 35 that covers the developing device 4, and is arranged to bite into the brush roller 38.

  The positional relationship between the collecting means and the supplying means is arranged so that the collecting means is above the supplying means, as shown in FIG. This is because the toner collected by the collecting means is mechanically scraped off by the flicker 39 and returned to the developing taste container 37 of the supplying means by gravity. The developing units of other colors are assumed to have the same positional relationship between the collecting unit and the supplying unit.

  In the developing device 4 configured as described above, the two-component developer accommodated in the developer accommodating portion 37 is conveyed while the screws 33 and 34 are agitated in opposite directions. In the communication portion on the near side and the far side of the developer accommodating portion 37, the developer moves from one chamber to the other chamber, so that the developer always circulates through the two chambers. Further, the developer stirred and conveyed by the screw 33 is held in the form of a magnetic brush on the surface by the magnetic force of the magnet of the supply roller 31 and is pumped up in the rotation direction of the supply sleeve 31. The developer on the magnetic brush that has been pumped up is cut into an appropriate amount by the doctor blade 32 and sent to the toner supply unit facing the toner conveying member 30. The developer remaining after being cut off by the doctor blade 32 is returned to the screw 33 and repeatedly supplied to the supply sleeve 31 while being stirred and conveyed again.

  On the other hand, a bias in which AC is superimposed on DC is applied to the supply roller 31, and toner is supplied to the toner conveying member 30 from the developer on the supply roller 31 sent to the toner supply unit. The toner conveying member 30 electrostatically conveys the toner supplied to the portion facing the photosensitive drum 1 as described above, and develops the electrostatic latent image formed on the photosensitive drum 1.

  The toner that has not contributed to the development on the toner conveying member 30 is electrostatically attracted to the brush roller 38 to which a bias voltage is provided downstream of the developing region in the toner conveying direction, and is separated from the toner conveying member 30. Is. Then, the toner electrostatically attracted to the brush roller 38 is mechanically peeled off by the flicker 39.

  By the way, when forming a color image, it is important to develop one isolated dot of 1200 [dpi] having a diameter of only about 30 [μm] with good reproducibility and without background stains. It is also important to prevent the toner from scattering inside and outside the apparatus. However, in a developing device using a rotationally driven developing roller, there is a problem that toner enters between the developing roller and the developing device side plate, and the toner is rubbed to cause toner fixation and the like, which adversely affects the image. . Further, the seal material around the developing device is deteriorated with time, so that the toner may be scattered and the image may be soiled. Further, in the case of charging the toner by frictional charging or corona discharge charging, the saturated charged toner and the unsaturated charged toner are mixed and have a large charge distribution. When such a toner is forcibly carried on a developing roller that rotates, the charge of the developer once carried on the developing roller is small at the developing speed of the developing roller (linear speed of about 100 cm / sec). The toner is detached, the toner is scattered, and the background of the formed image is easily generated. In this embodiment, since the developing roller is not rotationally driven as described above, these problems are solved. Therefore, there is an advantage that an image with good reproducibility and less toner scattering can be obtained.

  Next, an image forming apparatus according to a modification of the present embodiment will be described. FIG. 12 is a schematic configuration diagram of an image forming apparatus according to a modification. As in the image forming apparatus of FIG. 1, this image forming apparatus includes a photosensitive drum 1 at the center of the main body. Around the photosensitive drum 1, a charging device and a developing device for forming toner images of yellow (Y), magenta (M), cyan (C), and black (Bk) are clockwise from below. Four sets are arranged. Further, an exposure device 5 for irradiating the photosensitive drum 1 with laser light is provided on the right side of the device, and a laser for forming an electrostatic latent image of each color at an exposure portion between each charging device and each developing device. Irradiating light. As described above, in the image forming apparatus of FIG. 2, the rotation direction of the photosensitive drum 1 is opposite to that of the image forming apparatus of FIG. 1, and the positions of the toner image forming units arranged on the peripheral surface are different. However, the construction and operation in which the toner image is successively superimposed and developed on the photosensitive drum 1 and the residual toner after the transfer is cleaned by the cleaning device 14 are the same as described in FIG. The image forming apparatus shown in FIG. 12 is different from the apparatus shown in FIG. 1 in the configuration and operation of the toner image transfer / fixing device. The toner image is transferred and fixed onto the recording paper by the transfer fixing device 60 at the same time. This will be described below.

  A transfer fixing device 60 is provided after the developing device 4Bk for Bk. The transfer fixing device 60 has an endless transfer fixing belt 40. The transfer fixing belt 40 is stretched around a transfer roller 41 and a transfer fixing roller 42, and is rotationally driven by the transfer roller 42, which is a driving roller, by rotation. The transfer roller 41 has a function of forming a transfer nip for transferring the toner image from the photosensitive drum 1 onto the transfer fixing belt 40. Further, the transfer fixing roller 42 has a function as a counter roller facing the pressure roller 43 as a pressure member that contacts the transfer fixing belt 40 to form a fixing nip. Further, on the downstream side of the transfer nip and the upstream side of the fixing nip, as a heating means for heating and softening the toner image transferred from the photosensitive drum 1 onto the transfer fixing belt 40, electromagnetic induction facing the transfer fixing belt 40 is performed. A coil 44 is provided. A cooling roller 45 that contacts the transfer fixing belt 40 and cools the transfer fixing belt 40 is provided downstream of the fixing nip and upstream of the transfer nip.

  The transfer fixing belt 40 is provided with a metal layer such as copper or aluminum on a base material layer such as polyimide having a thickness of about 50 to 100 [μm], an elastic layer such as silicon rubber thereon, and a PFA coat on the surface layer. The release layer is formed by coating. The pressure roller 43 has a core metal and an elastic layer such as rubber. The cooling roller 45 is composed of a metal roller or a heat pipe.

  The operation of the transfer fixing device 60 having such a configuration will be described. The transfer fixing roller 42 is rotated by a driving unit (not shown), and the transfer fixing belt 40 is rotated accordingly. A bias is applied to the transfer roller 41 at the transfer nip, and the toner image on the photosensitive drum 1 is electrostatically transferred onto the transfer fixing belt 40. The toner image transferred onto the transfer and fixing belt 40 is heated and softened by the electromagnetic induction coil 44 while being conveyed to the fixing nip by the rotation of the transfer and fixing belt 40. By energizing the electromagnetic induction coil 44 with alternating current, a magnetic flux penetrating through the metal layer of the transfer fixing belt 40 provided opposite to the magnetic induction coil 44 is generated, and an overcurrent occurs in the metal layer to generate heat. Soften. The softened toner image is simultaneously transferred and fixed onto the recording paper when the recording paper sent from the registration roller 25 passes through the fixing nip formed by the transfer fixing belt 40 and the pressure roller 43. On the downstream side of the fixing nip, the transfer fixing belt 40 heated by the cooling roller 45 is cooled to prevent the temperature of the photosensitive drum 1 from rising. This prevents problems due to heat applied to the developing device 4 and the photosensitive drum 1 for developing toner.

  As described above, since the transfer and fixing device 60 simultaneously performs transfer and fixing to the recording paper, the device can be further miniaturized. Further, since the transfer and fixing of the toner onto the recording paper are performed in one step, the conveyance jam of the recording paper is reduced. Further, since the toner heating time can be lengthened in the above configuration, there is an advantage that low temperature, energy saving, and rise time are shortened. Furthermore, since the nip width at the time of toner transfer and fixing to the recording paper can be reduced and the power consumption does not change regardless of the paper thickness, there is no need to fix the thick paper in the half speed mode.

  Next, an image forming apparatus according to another modification of the present embodiment will be described. FIG. 13 is a schematic configuration diagram of an image forming apparatus according to another modification. As in the image forming apparatus of FIG. 1, this image forming apparatus includes a photosensitive drum 1 at the center of the main body. A charging device and a developing device for forming toner images of respective colors of yellow (Y), magenta (M), cyan (C), and black (Bk) are provided around the photosensitive drum 1 as in FIG. Four sets are arranged counterclockwise from above. Further, an exposure device 5 for irradiating the photosensitive drum 1 with laser light is provided on the right side of the device, and a laser for forming an electrostatic latent image of each color at an exposure portion between each charging device and each developing device. Irradiating light. The construction and operation for sequentially superposing and developing toner images on the photosensitive drum 1 and for cleaning the residual toner after transfer are the same as described in FIG. The image forming apparatus in FIG. 13 is different in operation from the configuration of the toner image transfer / fixing device on the photosensitive drum 1, and the toner image is transferred from the photosensitive drum 1 to the transfer fixing device 60 via the intermediate transfer device 61. Then, the toner image is transferred and fixed onto the recording paper by the transfer fixing device 60 at the same time.

The image forming apparatus according to this modification includes an intermediate transfer device 61 having an intermediate transfer belt 46 on which a toner image on the photosensitive drum 1 is primarily transferred, and a toner image on the transfer fixing device 60 via the intermediate transfer device 61. Secondary transfer is performed, and the toner image is transferred and fixed onto the recording paper by the transfer fixing device 60 at the same time. The intermediate transfer device 62 has an endless intermediate transfer belt 46 that is stretched around rollers 47, 48, and 49. It is rotationally driven by the rotation of a roller 47 that is a driving roller. The roller 49 is a transfer roller 49 that forms a primary transfer nip for primarily transferring a toner image from the photosensitive drum 1 onto the intermediate transfer belt 46. The roller 47 functions as a transfer roller 47 that forms a secondary transfer nip for secondary transfer of the toner image from the intermediate transfer belt 46 to the transfer fixing roller 51 of the transfer fixing device 60. A cooling roller (not shown) that contacts the intermediate transfer belt 46 and cools the intermediate transfer belt 46 is provided downstream of the secondary transfer nip and upstream of the primary transfer nip. Further, belt cleaning means (not shown) for cleaning the residual toner on the intermediate transfer belt 46 after the toner image is transferred to the transfer fixing roller 51 is provided.

The transfer fixing device 60 is a transfer fixing roller 51 as a transfer body to which a toner image is secondarily transferred from the intermediate transfer belt 46 while being rotationally driven, and a pressure member that contacts the transfer fixing roller 51 to form a fixing nip. The pressure roller 52 is provided. In addition, downstream of the secondary transfer nip and upstream of the fixing nip, an electromagnetic facing the transfer fixing roller 51 as a heating unit for heating the toner image transferred from the photosensitive drum 1 onto the transfer fixing roller 51. An induction coil 53 is provided.

The intermediate transfer bell 46 is made of polyimide or the like. Further, the transfer fixing roller 51 is formed by providing a metal layer such as copper or aluminum on a base material layer such as polyimide, providing an elastic layer such as silicon rubber thereon, and coating a release layer such as a PFA coat on the surface layer. Formed. The pressure roller has a core metal and an elastic layer such as rubber.

  The transfer / fixing operation of the intermediate transfer device 61 and the transfer fixing device 60 having such a configuration will be described. The driving roller 47 is rotated by driving means (not shown), and the intermediate transfer belt 46 is rotated accordingly. In the primary transfer nip, a bias is applied to the transfer roller 49, and the toner image on the photosensitive drum 1 is electrostatically transferred to the intermediate transfer belt 46. The transferred toner is conveyed to a secondary transfer nip formed between the transfer and fixing roller 51 by the rotation of the intermediate transfer belt, and electrostatically transferred onto the transfer and fixing roller 51. At this time, a bias is applied to either the drive roller 47 or the transfer fixing roller 51. The toner image on the transfer and fixing roller 51 is heated and softened by the electromagnetic induction coil 54 during conveyance to the fixing nip by the rotation of the transfer and fixing roller 51. The method of softening the electromagnetic induction coil 54 is the same as that of the transfer fixing device 60 of FIG. On the downstream side of the secondary transfer nip, a cooling roller (not shown) cools the intermediate transfer belt 46 whose temperature has been increased by the heat propagated from the transfer fixing roller 51 to prevent the temperature of the photosensitive drum 1 from rising. This prevents problems due to heat applied to the developing device 4 and the photosensitive drum 1 for developing toner.

  As described above, in the case where the toner image is transferred from the photosensitive drum 1 to the transfer fixing device 60 via the intermediate transfer device 61, and the toner image is transferred and fixed onto the recording paper simultaneously by the transfer fixing device 60, the device is further downsized. In addition, the heat of the transfer fixing roller 51 can be cooled by the intermediate transfer belt 46, and heat transfer to the photosensitive drum 1 side can be suppressed.

  Next, an image forming apparatus according to another modification of the present embodiment will be described. In this image forming apparatus, a static elimination charger is provided downstream of the second color developing device 4M. 14 is a schematic configuration diagram in which a static elimination charger 54 is provided in the image forming apparatus of FIG. 1, and FIG. The neutralization charger 54 neutralizes the electric charge of the toner developed on the photosensitive drum 1 so as to make the surface potential on the photosensitive drum 1 uniform once. FIG. 16 is an explanatory view showing the potential when the photosensitive drum 1 is overdeveloped. Vd is a charged photosensitive drum potential, Vb is a bias voltage applied to the toner conveying member 30, and Vl is a photosensitive drum potential after exposure. When the toner is developed, the potential is raised by the charge of the toner. When the toner adhesion amount increases due to color superposition, the potential further increases due to the charge, and the potential difference from the portion without toner gradually increases. As the color develops later, the difference in the toner adhesion amount increases, so the potential difference after the exposure also increases, and the desired toner adhesion amount cannot be obtained, resulting in image degradation. Therefore, as shown in FIGS. 14 and 15, by providing a static elimination charger 54 and neutralizing the surface of the photosensitive drum 1 once before the potential difference becomes large, image deterioration can be prevented.

As described above, according to the image forming apparatus of the present embodiment, the developing device 4 using the toner conveying member 30 that moves and develops the toner by the traveling wave electric field is employed, and it is not necessary to rotate the toner conveying member 30. Therefore, the degree of freedom is large. In other words, the portion of the toner conveying member 30 that faces the photosensitive drum 1 can be formed into a small shape, and the space on the peripheral surface of the photosensitive drum 1 that is necessary for disposing the developing device 4 can be reduced. Therefore, even in a device in which a large number of image forming process means such as a plurality of charging devices 2, a plurality of exposure units 3, and a plurality of developing devices 4 are arranged on the peripheral surface of the photosensitive drum 1, the entire device becomes large. This can be suppressed. Further, even when it is necessary to increase the circumferential length of the toner conveying member 30, it is possible to cope with the toner conveying member 30 with its portion facing the photosensitive drum 1 being in a small shape, and the entire apparatus is large. Can be avoided. Accordingly, a large number of image forming process means can be arranged on the circumferential surface of the small-diameter photosensitive drum, and the image forming apparatus can be downsized. Further, since the degree of freedom of the shape of the toner conveying member 30 is large, the degree of freedom of arrangement of each image forming process unit is also increased, and it is easy to avoid that the image quality is deteriorated due to mutually restrictive conditions.
Further, in the developing device 4, since the toner is hopped on the toner conveying member 30 by the traveling wave electric field and developing is performed without losing the adhesion force, the development device 4 cannot be realized by the configuration using the rotationally driven developing roller. As a result, it is possible to realize non-contact development with extremely high efficiency. Therefore, a high-voltage power source such as jumping development using a rotationally driven developing roller is not necessary.
As described above, the space on the peripheral surface of the photosensitive drum 1 necessary for disposing the developing device 4 is made small, the space shape has a degree of freedom, and a high-voltage power source for non-contact development is unnecessary. By doing so, the apparatus can be miniaturized.
Further, the transfer and fixing belt 40 to which the toner image on the photosensitive drum 1 is transferred while moving endlessly, the electromagnetic induction coil 54 for heating the toner image on the transfer and fixing belt 40, and the pressure facing the transfer and fixing belt 40. A toner image softened on a recording medium passing between the transfer fixing belt 40 and the pressure roller 43 by softening the toner image transferred to the transfer fixing belt 40 by the electromagnetic induction coil 54. The image forming apparatus includes a transfer fixing device 60 that simultaneously fixes the toner. Since the transfer and fixing device 60 simultaneously performs transfer and fixing to a recording sheet, the device can be further miniaturized. Further, since the transfer and fixing of the toner onto the recording paper are performed in one step, the conveyance jam of the recording paper is reduced. Further, in the configuration in which the toner image on the transfer and fixing belt 40 facing the electromagnetic induction coil 54 is heated, the heating time of the toner can be increased as compared with a normal fixing device, so that the low temperature, energy saving, and rise time are shortened. In addition, the nip width at the time of toner transfer and fixing onto the recording paper can be reduced, and the power consumption does not change regardless of the thickness of the paper, so that it is not necessary to fix the thick paper in the half speed mode.
Further, an intermediate transfer device 61 is provided between the photosensitive drum 1 and the transfer fixing device 60, and the toner image on the photosensitive drum 1 is transferred to the transfer fixing device 60 via the intermediate transfer device 61. Thereby, it is possible to suppress the heat of the transfer fixing device 60 from being directly transmitted to the photosensitive drum 1.
Further, by making the toner conveying member 30 of the developing device 4 into an oval or elliptical shape, the area occupied by the toner conveying member 30 on the circumferential surface of the photosensitive drum 1 can be reduced, and the toner supply area and the recovery area can be reduced. The degree of freedom of arrangement of the area increases. As a result, it is possible to configure a supply unit capable of stabilizing the characteristics of the supplied toner and a recovery unit with high recovery efficiency, thereby improving the image quality.
Further, by using a toner supply unit having the same configuration as that of an ordinary two-component developing device, the toner can be frictionally charged more stably than a normal one-component system, and stress on the toner can be reduced. . Therefore, even when the toner is repeatedly used in a circulating manner, variation in the toner charge amount is reduced, and it is possible to stably supply the toner with stable charging characteristics to the toner conveying member, thereby suppressing image quality deterioration.
In addition, a rotating brush roller 38 provided as a collecting unit facing the toner conveying member 30 and a flicker 39 that contacts the brush roller 38 are provided, and a bias is applied to the brush roller. By such a collecting means, the toner can be easily and reliably collected from the toner conveying member 30, and the collected toner can be easily separated from the brush.
Further, by providing the recovery means above the toner supply means, the toner recovered from the toner conveying member 30 can be returned to the toner supply means by gravity. As a result, the toner can be circulated and used with a simple configuration.
In addition, since the toner conveying member 30, the toner supply unit, and the recovery unit are configured in the integrated case 35, the scattered toner flows out to prevent image deterioration and contamination inside and outside the apparatus.
Further, when the toner image is superimposed on the photosensitive drum 1 by repeating charging, exposure, and development, the surface potential corresponding to the charge of the toner rises when the toner overlaps, so that a potential difference from where no toner is present occurs. As the color is developed later, the potential difference becomes larger, and the difference in adhesion amount results in image deterioration. Therefore, a neutralizing device is provided in the middle of repeated development of toners having different colors. In the image forming apparatus of the above-described embodiment, the static elimination charger 54 is provided downstream of the second color developing device 4M. As a result, it is possible to prevent image deterioration by performing static development in the middle of the over-development, aligning the surface potential of the toner layer having the superposed charge with the surface where there is no charge, and further over-developing.

1 is a schematic configuration diagram of an entire image forming apparatus according to an exemplary embodiment. FIG. 3 is a schematic configuration diagram of a developing device using a toner conveying member. FIG. 4 is a schematic diagram of a periphery of a facing portion between a toner conveying member and a photosensitive drum. FIG. 6 is an explanatory plan view of a toner conveying member. Cross-sectional explanatory drawing which follows the AA line of FIG. Cross-sectional explanatory drawing which follows the BB line of FIG. Cross-sectional explanatory drawing which follows the CC line | wire of FIG. Cross-sectional explanatory drawing which follows the DD line | wire of FIG. FIG. 4 is an explanatory diagram illustrating an example of a pulse-like driving waveform applied to a toner conveying member. FIG. 4 is an explanatory diagram of a state of toner on a toner conveying member. FIG. 4 is an explanatory diagram illustrating a state in which toner moves on a toner conveying member. 1 is a schematic configuration diagram of an image forming apparatus employing a transfer fixing device. FIG. 9 is a schematic configuration diagram of an image forming apparatus adopting a modification of the transfer fixing device. 1 is a schematic configuration diagram of an image forming apparatus provided with a static elimination charger. FIG. 6 is a schematic configuration diagram of a modified image forming apparatus provided with a charge removal charger. Explanatory drawing which shows the electric potential when carrying out the overlap development on the photoconductor drum.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2Y, M, C, Bk Charging device 3Y, M, C, Bk Exposure part 4Y, M, C, Bk Developing device 5 Exposure device 9 Transfer belt device 10 Drive roller 11 Follower roller 12 Transfer roller 13 Transfer belt DESCRIPTION OF SYMBOLS 14 Cleaning apparatus 18 Fixing apparatus 19 Fixing belt 21 Feed cassette 25 Registration roller 30 Toner conveyance member 31 Supply roller 32 Doctor blade 33,34 Screw 35 Case 36 Partition plate 37 Developer accommodating part 38 Brush roller 39 Flicker 40 Transfer fixing belt 41 Transfer roller 42 Transfer fixing roller 43 Pressure roller 44 Electromagnetic induction coil 45 Cooling roller 46 Intermediate transfer belt 47 Drive roller 49 Transfer roller 51 Transfer fixing roller 52 Pressure roller 53 Electromagnetic induction coil 54 Static elimination charger 60 Transfer fixing device 61 Intermediate transfer device 101 Support substrate 102 Electrode 103 Surface protective layer 105 Common electrode 106 Drive circuit

Claims (9)

A plurality of sets of charging devices, image exposure units, and developing devices are arranged on the peripheral surface of the image carrier that moves on the surface, and the image carrier is repeatedly charged, exposed, and developed a plurality of times on the image carrier. In an image forming apparatus for forming a superimposed toner image,
The developing device includes a toner conveying member that conveys toner to a developing area facing the image carrier by a traveling wave electric field generated on a surface, a toner supply unit that supplies toner to the toner conveying member, and the developing area. An image forming apparatus comprising: a collecting unit that collects the toner that has passed from the toner conveying member.   2. The image forming apparatus according to claim 1, wherein a transfer body to which the toner image on the image carrier is transferred while being moved endlessly, a heating means for heating the toner image on the transfer body, and downstream of the heating means. A pressure member facing the transfer body, the toner image transferred onto the transfer body is softened by the heating means, and the softened toner image is interposed between the transfer body and the pressure member. An image forming apparatus comprising a transfer fixing device that simultaneously fixes and transfers onto a recording medium that passes through the recording medium.   3. The image forming apparatus according to claim 2, wherein an intermediate transfer member is provided between the image carrier and the transfer member, and a toner image on the image carrier is transferred to the transfer member via the intermediate transfer member. An image forming apparatus.   4. The image forming apparatus according to claim 1, wherein the toner conveying member has an oval shape or an oval shape.   5. The image forming apparatus according to claim 1, wherein the toner supply unit carries a developer stirring member that stirs a developer composed of toner and a carrier to frictionally charge the developer, and carries the frictionally charged developer. An image forming apparatus comprising: a supply roller for conveying; and a regulating member for thinning a developer on the supply roller.   6. The image forming apparatus according to claim 1, wherein the collecting means includes a brush roller provided facing the toner conveying member, a flicker that contacts the brush roller, and a bias applied to the brush roller. An image forming apparatus comprising: a bias applying unit for applying the image forming apparatus.   7. The image forming apparatus according to claim 6, wherein the collecting unit is provided above the toner supply unit.   8. The image forming apparatus according to claim 7, wherein the toner conveying member, the toner supplying unit, and the collecting unit are arranged in a case and integrally configured.   9. The image forming apparatus according to claim 1, wherein a charge eliminating device is provided at least at one position between the developing device and a charging device adjacent to the downstream side. An image forming apparatus.

Images