JP4734142B2 - Developing device, process cartridge, and image forming apparatus - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, a process cartridge, and an image forming apparatus, and more specifically, a developing device capable of obtaining high developing efficiency by low voltage driving using an ETH (Electrostatic Transport & Hopping) phenomenon, and a process cartridge including the developing device And an image forming apparatus.

  As an image forming apparatus such as a copying machine, a printer, or a facsimile machine, an electrophotographic process is used to form a latent image on a latent image carrier, and a developer (hereinafter referred to as toner) that is a powder is formed on the latent image. In some cases, the toner image is visualized as a toner image by being attached and developed, and this toner image is transferred to a recording medium, or once transferred to an intermediate transfer member and then transferred to a recording medium to form an image.

  In such an image forming apparatus, as a developing device for developing a latent image formed on a latent image carrier, conventionally, the toner stirred in the developing device is carried on the surface of a developing roller which is a developer carrier. Then, by rotating the developing roller, the developing roller 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 that has not been transferred to the latent image carrier is collected in the developing device by the rotation of the developing roller. The toner is newly stirred and charged, and is again carried on the developing roller and transported. Things are known.

On the other hand, a non-contact type developing device that performs development without bringing a developing roller into contact with a latent image carrier has been attracting attention. For example, a method using a traveling wave electric field has been proposed. In a developing device using such a traveling wave electric field, on the outside of the width direction perpendicular to the arrangement direction of each electrode on the developer conveying member (on both sides in the width direction perpendicular to the conveying direction of the developer conveying member) Each wiring pattern is provided. In that case, in the region where the wiring pattern is located, the traveling wave electric field condition is not formed because it is located outside each electrode, and if the developer enters this region, the developer is scattered or fixed. There is a fear. According to Patent Document 1 as one of proposals for solving such problems, an electrostatic latent image is arranged in a developing region facing an image carrier carried on the surface thereof, and is predetermined on a substrate. A developer carrying member formed by coating a plurality of electrodes arranged at intervals with a surface protective layer, and the developer is applied to the developer carrying member by a traveling wave electric field formed by applying a multiphase voltage to each electrode. In the developing device transported by the above, a supply member for supplying the developer is provided on the developer transport member. The effective electrode width Le in the width direction orthogonal to the arrangement direction of the electrodes and the length Lt in the width direction orthogonal to the developer supply direction of the developer existing area on the supply member are expressed as Lt <Le. Set to satisfy the relationship. In this way, the supply width is narrower than the conveyance width, thereby preventing the toner from escaping outside the conveyance area.
Patent No. 3,639,545

  However, in Patent Document 1 described above, since the electric field is applied to the wiring electrode when the toner is conveyed, the toner is conveyed in a wider range in the longitudinal direction than the conveying area, and the toner reaches the area where the wiring pattern is located. I will enter. In addition, the developing device that transports the toner on the traveling wave is transported without any problem where the traveling wave is generated side by side, but the edge portion has a bus line (common electrode), and the traveling direction is in that portion. Since the electrodes are not lined up, if the toner adheres, it stops moving and accumulates.

  The present invention is intended to solve these problems, and provides a developing device, a process cartridge, and an image forming apparatus that can achieve high development efficiency with low voltage driving by using an ETH (Electrostatic Transport & Hopping) phenomenon. The purpose is to do.

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

  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”.

In order to solve the above problems, a developing device of the present invention is disposed opposite to a latent image carrier, and includes a transport member having a plurality of transport electrodes for generating a traveling wave electric field for moving powder, A powder supply mechanism for supplying the powder to the conveying member, and a recovery mechanism for recovering excess powder that has not been used for development in the latent image carrier from the latent image carrier to the powder supply mechanism. And a developing device for developing the latent image on the latent image carrier by attaching powder onto the latent image carrier. According to the developing device of the present invention, the conveying member includes, along the conveying direction, a supply conveying area for conveying the powder from the powder supply mechanism to the latent image carrier, and the powder conveyed to the supply conveying area. A developing area where the body adheres to the latent image carrier to form a latent image, and a recovery conveyance area where excess powder is conveyed from the latent image carrier to the powder supply mechanism, and the powder is supplied and conveyed The film thickness of the first insulating layer that covers at least the surface of the transport electrode in the region other than the transport region that is transported through the region, the development region, and the collection transport region in order is the thickness that covers at least the surface of the transport electrode in the transport region . It is characterized by being thicker than the thickness of the insulating layer 2 . Therefore, the force necessary for conveying the powder does not act outside the conveying area, so that the powder can be prevented from being scattered or fixed.

Moreover, it is preferable that the film thickness of a 1st insulating layer is 80 micrometers or more.

Furthermore, since the first and second insulating layers are formed by a thin film forming method, a very dense film can be formed, so that an insulating film excellent in insulation and wear resistance can be formed. Powder scattering and sticking can be further prevented.

In addition, the first and second insulating layers can be formed by a screen printing method to form an insulating layer in a predetermined plane shape, and the insulating layer is formed after the transfer substrate is processed into a cylindrical shape. Can do.

Furthermore, since the first and second insulating layers are formed of a tape using an insulating resin, a relatively thick insulating film can be easily formed. After processing the transfer substrate into a cylindrical shape, the insulating film Can be formed.

  A process cartridge as another invention includes at least the developing device and is detachable from the main body of the image forming apparatus. Therefore, it is possible to provide a process cartridge that can be driven at a low voltage and can perform high-quality development with high development efficiency to form a high-quality image.

  Furthermore, an image forming apparatus as another invention includes the developing device or the process cartridge. Therefore, a high quality image can be formed.

  Further, according to another image forming apparatus, a plurality of the process cartridges can be provided to form a high-quality color image.

  The developing device of the present invention is characterized in that an insulating layer thicker than the surface layer on the conveying member is provided in an area other than the area where the powder is conveyed by the conveying member. Therefore, since the force necessary for conveying the powder does not act outside the conveying area, it is possible to prevent the powder from scattering and sticking.

  FIG. 1 is a schematic view showing a configuration of a developing device according to an embodiment of the present invention. A developing device 10 shown in FIG. 1 includes a transport substrate 11 that is a transport member having a plurality of transport electrodes 102 for generating an electric field for transporting, hopping, and collecting the toner T that is powder. The drive waveforms Va1, Vb1, Vc1 and Va2, Vb2, Vc2 of n phases (here, three phases) for generating a required electric field from the drive circuit 12 are applied to each of the eleven transport electrodes 102. Is done. Here, the transport substrate 11 transfers the toner T to the photosensitive drum in relation to the range of the transport electrode 102 that gives drive waveforms Va1, Vb1, Vc1 and Va2, Vb2, Vc2, and the photosensitive drum 20 that is a latent image carrier. A transport region for transporting to the vicinity of 20, a development region for forming a toner image by attaching toner T to the latent image on the photosensitive drum 20, and a recovery after passing through the development region for recovering the toner T to the transport substrate 11 side. Divided into areas.

  In the developing device 10, the toner T is transported to the vicinity of the photosensitive drum 20 in the transport region of the transport substrate 11, and the toner T is exposed to the image portion of the latent image on the photosensitive drum 20 in the development region. In order to perform development by forming an electric field in a direction toward the drum 20 and on the non-image portion in a direction in which the toner T is directed to the opposite side (conveying substrate side) from the photosensitive drum 20. In the recovery region, the toner T forms an electric field in a direction toward the opposite side (conveying substrate 11 side) from the photosensitive drum 20 for both the image portion and the non-image portion of the latent image.

  Here, the configuration of the transport substrate in the developing device according to the present embodiment will be described in detail with reference to FIGS. 2 is a plan view of the transfer substrate, FIG. 3 is a cross-sectional view taken along line AA ′ in FIG. 2, FIG. 4 is a cross-sectional view taken along line BB ′ in FIG. 2, and FIG. FIG. 6 is a sectional view taken along the line DD ′ of FIG.

  The transport substrate 11 in the developing device according to the present embodiment is a set of three transport electrodes 102a, 102b, and 102c (collectively referred to as the transport electrode 102) on the support substrate 101 of FIG. It is repeatedly formed and arranged at a predetermined interval along the toner conveyance direction indicated by the arrow in FIG. 3 and in a direction substantially orthogonal to the toner conveyance direction, and becomes an insulating conveyance surface forming member that forms a conveyance surface thereon. A surface protective layer 103 made of an inorganic or organic insulating material, which serves as a protective film covering the surfaces of the transport electrodes 101, is laminated. Here, the surface protective layer 103 forms the transport surface, but a surface layer having excellent compatibility with the powder (toner) can be additionally formed on the surface protective layer 103.

  On both sides of the transport electrodes 102a, 102b, and 102c, common electrodes 104a, 104b, and 104c (collectively referred to as the common electrode 104) interconnected with the transport electrodes 102a, 102b, and 102c at both ends are collectively referred to as a toner transport direction. , That is, in a direction substantially orthogonal to each of the transport electrodes 102a, 102b, and 102c. In this case, the width of the common electrode 104 (this width is a width in the direction orthogonal to the toner conveyance direction) is larger than the width of the conveyance electrode 102 (this width is a width along the toner conveyance direction). In FIG. 2, the common electrode 104 is distinguished from the common electrodes 104a1, 104b1, and 104c1 in the transport region, the common electrodes 104a2, 104b2, and 104c2 in the development region, and the common electrodes 104a3, 104b3, and 104c3 in the recovery region. ing.

  Here, as shown in FIG. 4, the pattern of the common electrodes 104 a, 104 b, and 104 c is formed on the support substrate 101, the interlayer insulating film 105 is formed, and the contact hole 106 is formed in the interlayer insulating film 105 and then transported. By forming the electrodes 102a, 102b, 102c, the transport electrodes 102a, 102b, 102c and the common electrodes 104a, 104b, 104c are interconnected, respectively. Note that the interlayer insulating film 105 may be either the same material as the surface protective layer 103 or a different material. Further, an interlayer insulating film 105 is formed on a pattern in which the transport electrode 102a and the common electrode 104a are integrally formed, and a pattern in which the transport electrode 102b and the common electrode 104b are integrally formed is formed on the interlayer insulating film 105, and further, an interlayer insulating film is formed. A film 105 is formed, and a pattern in which the transport electrode 102c and the common electrode 104c are integrally formed is formed on the interlayer insulating film 105. That is, the electrode can have a three-layer structure, or can be integrally formed with an interconnect. Interconnection by the contact hole 106 can also be mixed.

  Further, these common electrodes 104a, 104b, 104c are provided with drive signal application input terminals (not shown) for inputting drive signals (drive waveforms) Va, Vb, Vc from the drive circuit 12 of FIG. Provided. This drive signal input terminal may be provided on the back surface side of the support substrate 101 and connected to each common electrode 104 through a through hole, or may be provided on the interlayer insulating film 105.

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, 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 transport electrode 102 is formed by depositing 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 used by patterning into the required electrode shape. The width L in the powder traveling direction of the plurality of transport electrodes 102 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 transport electrode 102 is also moved. 1 to 20 times the average particle size.

Furthermore, as the surface protective layer 103, for example _{SiO 2, TiO 2, TiO 4} , SiON, BN, TiN, Ta 2 O 5, ZrO 2, BaTiO 3 and thickness like 0.5 to 10 [mu] m, preferably a thickness of 0 It is formed by forming a film with a thickness of 5 to 3 μm. In addition, inorganic nitride compounds such as SiN and BN can be used.

  In the developing device of this embodiment, the insulating layer 107 is formed thicker than the transport region in the region other than the transport region (the outer portion in the longitudinal direction). The electric field strength that contributes to the transfer can be different between the transfer region and the other regions, and the electric field strength of the surface in the direction in which the transfer is desired is greater than the electric field strength of the surface in the region where the insulating layer 107 is located. Becomes stronger. Therefore, the charged toner moves in the transport direction.

  Accordingly, the charged toner particles are transported without departing from the transport region and are transported to the development region. In addition, by providing a thickness difference between the transport area and the area outside the transport area, the space in the transport area is increased, and the toner can easily move in the transport area, and as a result, the diffusion of the toner to the area outside the transport area is suppressed. be able to.

  In FIG. 2, an insulating layer 107 is formed in an area outside the transport region. The thickness of the insulating layer and the electric field strength in the traveling direction are obtained by calculation as shown in FIG. By making the insulating layer 107 in the area thicker than the surface insulating layer in the transport region, the electric field in the direction of the bus line (common electrode) is weakened in the traveling direction. More preferably, if the insulating film has a thickness of 80 μm or more, the force for moving the toner toward the outer periphery due to the electric field is reduced, and the toner does not actually work, so that the toner can be prevented from adhering to the area outside the transport region.

  The insulating layer 107 to be formed can be formed using the same material as the surface protective layer. As a method for forming the insulating layer 107, there are thin film forming methods such as vacuum deposition and sputtering. In addition, it is also useful means to form a resin paste only on a predetermined portion by plating or printing. It is also useful to directly form an insulating resin layer. Furthermore, since the insulating film formed by the vacuum evaporation method can form a very dense film, it has excellent insulating properties.

  This is an example in which a screen printing method is used for forming an insulating film. In the screen printing method, a predetermined layer is formed on a substrate using an epoxy resin or the like through an opening of a mask. When formed by the printing method, an arbitrary resin pattern can be formed. Therefore, an opening can be provided in the insulating layer to form an electrode outlet.

In this example, the insulating layer is formed by attaching a tape. For example, it can be easily formed by bonding a tape having a 10 μm acrylic adhesive layer to a 70 μm polyester base material. The thickness of the insulating layer can be controlled by selecting the thickness of the tape.
The tape base material only needs to be an insulating material, and is not limited to a polyester type, and a heat-resistant base material such as a urethane type, a fluorine type, a polyimide, or a polyamide can be used, and an adhesive is a urethane type or rubber. It can also be used in systems.

  Also, by making the thickness of the insulating layer the same as the development gap, the gap with the photoreceptor can be made constant, and the same function as a so-called gap roller can be achieved.

  By using a spherical toner having a circularity of 96% or more, variation in surface shape can be reduced as compared with an indeterminate shape such as pulverized toner, so that uniform conveyance is possible. That is, when the circularity is lower than 96%, the direction of repulsion when the toner collides with the substrate is random, and toner deviates from the transport direction. By defining such circularity, it is possible to prevent the toner from escaping to the bus line (common electrode).

  Next, the principle of electrostatic transport of toner on the transport substrate 11 configured as described above will be described. By applying an n-phase driving waveform to the plurality of transport electrodes 102 on the transport substrate 11, a phase shift electric field (traveling wave electric field) is generated by the plurality of transport electrodes 102, and the charged toner on the transport substrate 11 is In response to the repulsive force and / or suction force, it moves in the transfer direction including hopping and conveyance.

  For example, as shown in FIG. 7, with respect to the plurality of transport electrodes 102 of the transport substrate 11, a three-phase pulse-shaped drive waveform (drive signal) A (A) that changes between the ground G (0 V) and the positive voltage + is provided. Phase), B (B phase), and C (C phase) are applied at different timings.

  At this time, as shown in FIG. 8, there is negatively charged toner T on the transport substrate 11, and “G”, as shown in FIG. Assuming that “G”, “+”, “G”, and “G” are applied, the negatively charged toner T is positioned on the “+” transport electrode 102.

  At the next timing, “+”, “G”, “G”, “+”, and “G” are respectively applied to the plurality of transport electrodes 102 as shown in (2), and the same is applied to the negatively charged toner T. In the figure, a repulsive force acts between the left “G” transport electrode 102 and a suction force acts between the right “+” transport electrode 102, and therefore the negatively charged toner T is “+”. Move to the transport electrode 102 side. Further, as shown in (3), “G”, “+”, “G”, “G”, and “+” are respectively applied to the plurality of transport electrodes 102 at the next timing, and the negatively charged toner T is applied. Similarly, since the repulsive force and the attractive force act respectively, the negatively charged toner T further moves to the “+” conveying electrode 102 side.

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

  The state of the toner T conveyance will be described in detail with reference to FIG. 9. As shown in FIG. 9A, the conveyance electrodes A to F of the conveyance substrate 11 are all 0 V (G). When “+” is applied to the transport electrodes A and D from the state in which the negatively charged toner T is placed on the transport substrate 11, as shown in FIG. A is sucked by A and the transport electrode D and moves onto the transport electrodes A and D. At the next timing, as shown in FIG. 5C, when the transport electrodes A and D are both “0” and “+” is applied to the transport electrodes B and E, the transport electrodes A and D The upper toner T receives a repulsive force and also receives the suction force of the transport electrodes B and E, so that the negatively charged toner T is transported to the transport electrode B and the transport electrode E. Further, at the next timing, as shown in (d) of the figure, when the transport electrodes B and E are both “0” and “+” is applied to the transport electrodes C and F, the transport electrode B The toner T on E receives a repulsive force and also receives the suction force of the transport electrodes C and F, so that the negatively charged toner T is transported to the transport electrode C and the transport electrode F. As described above, the negatively charged toner is sequentially conveyed rightward in the drawing by the traveling wave electric field.

  Next, the overall configuration of the drive circuit of FIG. 1 will be described with reference to FIG. The drive circuit 12 includes a pulse signal generation circuit 21 that generates and outputs a pulse signal, and waveform amplifiers 22a and 22b that generate and output drive waveforms Va1, Vb1, and Vc1 by inputting the pulse signal from the pulse signal generation circuit 21. 22c and waveform amplifiers 23a, 23b, and 23c that receive the pulse signal from the pulse signal generation circuit 21 and generate and output drive waveforms Va2, Vb2, and Vc2. The pulse signal generation circuit 21 receives, for example, logic level input pulses, and includes two sets of pulses that are phase-shifted by 120 °, and switching means (included in the waveform amplifiers 22a to 22c and 23a to 23c in the next stage). For example, a pulse signal having an output voltage of 10 to 15 V at a level capable of switching 100 V by driving a transistor is generated and output.

  Further, the waveform amplifiers 22a, 22b, and 22c apply the + 100V application time ta for each phase to the respective transport electrodes 102 in the transport region and the respective transport electrodes 102 in the recovery region of FIG. 1, for example, as shown in FIG. Three-phase driving waveforms (driving pulses) Va1, Vb1, and Vc1 are set to about 33%, which is 1/3 of the repetition period tf (hereinafter referred to as “carrier voltage pattern” or “collected carrier voltage pattern”). Apply. Further, the waveform amplifiers 23a, 23b, and 23c repeat the application time ta of + 100V or 0V for each phase as shown in FIG. 12 or 13 for each transport electrode 102 in the development region of FIG. The three-phase drive waveforms (drive pulses) Va2, Vb2, and Vc2 are applied (hereinafter referred to as “hopping voltage pattern”).

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

  For example, in the case of a pulsed voltage waveform transitioning from 0 to −100 V as in the driving waveform of the hopping voltage pattern shown in FIG. 13 described above, when the non-image portion potential on the latent image carrier is lower than −100 V, For the image portion, the toner is directed to the latent image carrier, and for the non-image portion, the toner is directed to the opposite side of the latent image carrier. In this case, it was confirmed that when the potential of the non-image portion of the latent image is −150V or −170V described later, the toner moves toward the latent image carrier.

  Further, when the driving waveform of the hopping voltage pattern is a pulsed voltage waveform that transitions between 20 V and −80 V, the pulsed driving waveform is also obtained when the potential of the image portion is about 0 V and the potential of the non-image portion is −110 V. Similarly, since the low level potential is between the image portion potential of the latent image and the non-image portion potential, the toner is directed toward the latent image carrier for the image portion and the toner is applied to the non-image portion. It goes to the opposite side to the latent image carrier.

  In short, by setting the low-level potential of the pulse-shaped drive waveform to a potential between the potential of the latent image portion and the non-image portion, toner adhesion to the non-image portion is prevented and high quality is achieved. Development can be performed.

  In this way, in ETH development, because toner is hopping, the toner attracts and adheres to the image portion of the latent image, and the toner is repelled and does not adhere to the non-image portion. At this time, since the toner that has already been hopped does not generate an adsorbing force with the transport substrate 11, it can be easily transported to the latent image carrier side, and development with high image quality can be obtained. Can be performed at a low voltage.

  That is, in the conventional so-called jumping development method, in order to peel off the charged toner from the developing roller and transport it to the photoreceptor, an applied voltage higher than the adhesion force of the toner to the developing roller is required. A bias voltage must be applied. On the other hand, according to the present invention, the adhesion force of the toner is usually 50 to 200 nN, but since the adhesion force to the transport substrate 11 becomes substantially zero because of hopping on the transport substrate 1, the toner is removed. The force to peel off from the transport substrate 11 becomes unnecessary, and the toner can be sufficiently transported to the latent image carrier side at a low voltage.

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

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

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

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

  By the way, the above-described ETH development is performed by hopping the toner on the transport substrate 11 to reduce the adsorption force with the transport substrate 11 to 0, but the toner is simply hopped on the transport substrate. However, even if the hopped toner has progress toward the latent image carrier, the certainty that it adheres to the latent image on the latent image carrier is not guaranteed, and toner scattering occurs.

  Therefore, according to the present invention, in the ETH development, the hopped toner is selectively and reliably attached to the image portion of the latent image on the latent image carrier and does not adhere to the non-image portion, that is, the background is stained. This is what we found no conditions.

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

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

  Hereinafter, the electrode width L and electrode interval R of the plurality of transport electrodes 102 of the transport substrate 11 for transporting and hopping the toner, and the surface protective layer 103 will be described.

  The electrode width L and the electrode interval R on the transport substrate 11 greatly affect toner transport efficiency and hopping efficiency. That is, the toner between the transport electrodes moves to the adjacent transport electrodes on the substrate surface by a substantially horizontal electric field. On the other hand, since the toner on the transport electrode is given an initial velocity having at least a component in the vertical direction, most of the toner flies away from the substrate surface. In particular, since the toner near the electrode end surface moves over the adjacent transport electrode, when the electrode width L is wide, the number of toners on the electrode increases, and the toner having a large moving distance is generated. Increases transport efficiency. However, if the electrode width L is too wide, the electric field strength in the vicinity of the center of the electrode is lowered, so that the toner adheres to the carrying electrode and the carrying efficiency is lowered. Therefore, the present invention has found that there is an appropriate electrode width for efficiently conveying and hopping powder at a low voltage.

  The electrode interval R determines the electric field strength between the electrodes from the relationship between the distance and the applied voltage. The narrower the interval R, the stronger the electric field strength, and the easier the initial speed of conveyance and hopping. However, for toner that moves from the transport electrode to the transport electrode, the distance traveled once is shortened, and the travel efficiency cannot be increased unless the drive frequency is increased. Also in this regard, according to the present invention, it has been found that there is an appropriate electrode interval for efficiently conveying and hopping the powder at a low voltage.

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

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

  More specifically, the electrode width L is a width dimension for carrying and hopping at least one toner when the electrode width L is set to be one time the toner diameter (powder diameter). If it is narrower than this, the electric field acting on the toner is reduced, and the conveying force and the flying force are lowered, which is not sufficient in practical use. Further, as the electrode width L is increased, the electric field lines are inclined in the traveling direction (horizontal direction) particularly near the center of the upper surface of the electrode, a region having a weak vertical electric field is generated, and the hopping generation force is reduced. . When the electrode width L is too wide, in an extreme case, the image force according to the charged charge of the toner, the van der Waals force, the adsorbing force due to moisture, etc. may be superior, and toner deposition may occur.

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

  Therefore, a more preferable range of the electrode width L is 2 times to 10 times the average particle diameter of the powder in order to more efficiently drive the applied voltage based on the drive waveform at a low voltage of 100 V or less. By setting the electrode width L within this range, the decrease in electric field strength near the center of the electrode surface can be suppressed to 1/3 or less, and the decrease in hopping efficiency is 10% or less, resulting in a significant decrease in efficiency. Disappears. This corresponds to a range of 10 μm to 50 μm, for example, when the average particle diameter of the toner is 5 μm.

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

  Here, as shown in FIG. 14, the electrode width L of the transfer electrode 102 on the transfer substrate 11 of FIG. 1 is 30 μm, the electrode interval R is 30 μm, the thickness of the transfer electrode 102 is 5 μm, and the thickness of the surface protective layer 103 is 0. FIG. 15 and FIG. 16 show the results of measuring the strength of the carrier electric field TE and the hopping electric field HE with respect to the electrode width L and the electrode interval R by applying +100 V and 0 V to the two adjacent carrier electrodes 102, respectively. Yes.

  Each evaluation data is a result of actual measurement and evaluation by simulation and actual measurement, and behavior of particles by high-speed video. In FIG. 14, two transport electrodes 102 are shown for easy understanding of details, but an actual simulation and experiment evaluate an area having a sufficient number of transport electrodes as described above. The toner T has a particle size of 8 μm and a charge amount of −20 μC / g.

  The electric field strengths shown in FIGS. 15 and 16 are values of representative points on the electrode surface, and the representative point TEa of the carrier electric field TE is a point 5 μm above the end of the electrode shown in FIG. 14 and a representative point of the hopping electric field HE. HEa is a point 5 μm above the center of the electrode shown in FIG. 14 and corresponds to a representative point having the strongest electric field acting on the toner in the X direction and Y direction, respectively.

  From these FIGS. 15 and 16, the electric field capable of imparting a force acting on toner conveyance and hopping is (5E + 5) V / m or more, and the preferred electric field without the problem of adsorption is (1E + 6) V / m or more. It can be seen that a more preferable electric field capable of imparting a sufficient force is in the range of (2E + 6) V / m or more.

  Regarding the electrode interval R, since the electric field strength in the transport direction decreases as the interval increases, the value corresponding to the range of the electric field strength is the same, and as described above, the average particle size of the toner is 1 to 20 times or more. 2 times or less, preferably 2 times or more and 10 times or less, and more preferably 2 times or more and 6 times or less.

  Also, from FIG. 16, the hopping efficiency decreases as the electrode spacing R increases, but practical hopping efficiency can be obtained up to 20 times the average toner particle diameter. If the average particle diameter of the toner exceeds 20 times, the adsorbing force of a large amount of toner cannot be ignored, and a toner that does not generate hopping is generated. There is a need to.

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

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

  Further, when the toner has an average particle diameter of 2 to 10 μm and Q / M is negatively charged, it is −3 to −40 μC / g, more preferably −10 to −30 μC / g, and positively charged is +3 to +3. When the pressure was +40 μC / g, more preferably +10 to +30 μC / g, the conveyance and hopping by the electrode configuration described above could be efficiently performed.

  Next, the surface protective layer will be described. By providing the surface protective layer 103 in FIG. 3, the surface can be maintained under conditions suitable for transportation without contamination of the electrode and adhesion of fine particles. Creeping leaks can be avoided, there is no variation in Q / M, and the charged charge amount of the powder can be stably maintained.

  Here, FIG. 17 shows a result obtained by calculating the electric field strength in the X direction when the thickness of the surface protective layer 103 is changed in the range of 0.1 to 80 μm in the configuration of FIG.

  The dielectric constant ε of the surface protective layer 103 is higher than that of air, and is usually ε = 2 or more. As can be seen from the figure, when the surface protective layer 103 is too thick (thickness from the electrode surface), the electric field strength acting on the toner on the surface is lowered. Therefore, in consideration of transport efficiency, temperature and humidity resistance environment, and the like, the thickness of the surface protective layer 103 that can be practically used without causing a decrease in efficiency with respect to the transport operation is 10 μm or less, more preferably, 30% efficiency decreases. The efficiency reduction is 5 μm or less, which can be suppressed to several percent.

  Examples of the electric field strength acting on the electrode surface hopping are shown in FIGS. 18 shows an example in which the thickness of the surface protective layer 103 is 5 μm, and FIG. 19 shows an example in which the thickness of the surface protective layer 103 is 30 μm. In both cases, the applied voltage is 0 V and 100 V with an electrode width of 30 μm and an electrode interval of 30 μm.

  As can be seen from each of these figures, as the thickness of the surface protective layer 103 increases, the electric field from the protective layer having a dielectric constant higher than that of air toward the adjacent electrode increases, so that the vertical component of the surface decreases, The electric field strength acting on the toner on the surface is reduced by the thickness of the surface protective layer 103.

  That is, the electric field lines of the vertical component acting on hopping greatly depend on the thickness of the surface protective layer. An electric field capable of efficiently applying a force that acts on hopping at a low voltage of about 100 V is (1E + 6) V / m or more as a preferable electric field without the problem of adsorption, and a more preferable electric field capable of applying a sufficient force is (2E + 6). ) V / m or more, and the thickness of the surface protective layer therefor is 10 μm or less, more preferably 5 μm or less. As the material for the surface protective layer 103, it is preferable to use a material having a specific resistance of 10 * E6 Ωcm or more and a dielectric constant ε of 2 or more.

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

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

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

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

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

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

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

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

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

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

Next, an image forming apparatus of a first embodiment according to another invention equipped with the developing device of the present invention will be described with reference to FIG.
The overall outline and operation of this image forming apparatus will be described. A photosensitive drum 201 as a latent image carrier is formed by forming a photosensitive layer 203 on a substrate 202, and is driven to rotate in the direction indicated by an arrow in FIG. . The photosensitive drum 201 is uniformly charged by a charging device 204, and an electrostatic latent image is formed on the surface of the photosensitive drum 201 by writing with a laser beam corresponding to an image read from the exposure unit 205.

  The electrostatic latent image on the surface of the photosensitive drum 201 is visualized by attaching toner to the developing device 206 according to the present invention, and the visible image is fed from the paper feed cassette 207. The transfer paper 208 to which the voltage from the transfer power source 209 is applied to the transfer paper (recording medium) 208 is transferred and the visible image is transferred. The transfer paper 208 is separated from the surface of the photosensitive drum 201 and fixed. The visible image is fixed through the rollers of the unit 211 and discharged to a discharge tray outside the apparatus.

  On the other hand, the toner remaining on the surface of the photoconductive drum 201 after the transfer is removed by the cleaning device 212, and the electric charge remaining on the surface of the photoconductive drum 201 is erased by the charge eliminating lamp 213.

  Accordingly, the developing device of the present invention will be described. In the developing device 206, the charging brushes 214a and 214b are arranged so as to be in contact with each other and rotate as an example of a member for charging the toner, which is powder, and the toner is rotated. The toner T fed from the tank 215 is charged by receiving friction from the charging brushes 214a and 214b. Then, the charged toner T is sent to the transport substrate 216, transported and hopped on the transport substrate 216, and sent to the development area facing the latent image carrier 201, where necessary development is performed. Thereafter, the toner T used for development falls from the end of the transport substrate 216 and is transported back to a member (charging brush 214b) that charges the toner by the transport substrate 217 for reverse transport.

  The configurations of the transfer substrate 216 and the reverse transfer substrate 217 are the same as those of the transfer substrate 11 described above, and the configuration of a drive circuit that applies drive waveforms to the respective electrodes of the transfer substrate 216 and the reverse transfer substrate 217. Although not shown in the figure, it is the same as that described in each embodiment of the developing device.

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

Next, an image forming apparatus of a second embodiment according to another invention equipped with the developing device of the present invention will be described with reference to FIG.
The overall outline and operation of the image forming apparatus according to the second embodiment will be described. A photosensitive drum 301 (for example, an organic photoreceptor: OPC), which is a latent image carrier, is rotationally driven clockwise in FIG. The When a document is placed on the contact glass 302 and a print start switch (not shown) is pressed, a scanning optical system 305 including a document illumination light source 303 and a mirror 304 and a scanning optical system 308 including mirrors 306 and 307 are moved. The original image is read. Here, the scanned original image is read as an image signal by the image reading element 310 disposed behind the lens 309, and the read image signal is digitized and subjected to image processing. Then, the laser diode is driven by the signal subjected to the image processing, the laser light from the laser diode is reflected by the polygon mirror 311, and then irradiated onto the photosensitive drum 301 through the mirror 312. The photosensitive drum 301 is uniformly charged by a charging device 313, and an electrostatic latent image is formed on the surface of the photosensitive drum 301 by writing with a laser beam.

  The electrostatic latent image on the surface of the photosensitive drum 301 is visualized by attaching toner to the developing device 314 according to the present invention, and the visible image (toner image) is supplied to the paper feeding unit 315A or 315B. To the transfer paper (recording medium) 317 fed from the feed roller 316A or 316B by the corona discharge of the transfer charger 318. The transfer sheet 317 to which the visible image is transferred is separated from the surface of the photosensitive drum 301 by the separation charger 319, conveyed by the conveyance belt 320, and passed through the pressure contact portion of the fixing roller pair 321 so that the visible image is transferred. The paper is fixed and discharged to a discharge tray 322 outside the apparatus.

  On the other hand, the toner remaining on the surface of the photosensitive drum 301 after the transfer is removed by the cleaning device 323, and the charge remaining on the surface of the photosensitive drum 301 is erased by the charge eliminating lamp 324.

  As shown in FIG. 22, the developing device 314 in FIG. 21 includes a toner hopper unit 325 for storing toner, an agitator 326 for agitating the toner in the toner hopper unit 325, and the toner in the toner hopper unit 325 to charge the toner box. A charging roller 328 supplied to the section 327, and a doctor blade 329 arranged in contact with the peripheral surface of the charging roller 328. In addition, the toner supplied to the toner box 325 is transported for development and transported for hopping, and the toner that has not been used for development falling from the end of the transport substrate 330 is charged. And a reverse transport substrate 331 for transporting in a direction to return to the charging roller 328 as a member to be applied.

  As described in the first embodiment, the configuration of the transfer substrate 330 and the reverse transfer substrate 331 is the same as that of the transfer substrate 11 described above, and the transfer substrate 330 and the reverse transfer substrate. The configuration of a drive circuit that applies a drive waveform to each of the transport electrodes 331 is not shown, but is the same as that described in each embodiment of the developing device described above.

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

  Next, an image forming apparatus according to a third embodiment provided with a process cartridge according to another invention will be briefly described with reference to FIGS. FIG. 23 is a schematic configuration diagram of an image forming apparatus provided with a process cartridge, and FIG. 24 is a schematic configuration diagram of the process cartridge.

  An image forming apparatus 400 shown in FIG. 23 is an example of a laser printer that forms a full-color image with four colors of magenta (M), cyan (C), yellow (Y), and black (Bk), and an image signal for each color. Four optical writing devices 401-M, 401-C, 401-Y, 401-Bk (hereinafter collectively referred to as optical writing device 401) that emit laser beams according to the above, and four processes for image formation Cartridges 402-M, 402-C, 402-Y, and 402-Bk (hereinafter collectively referred to as process cartridge 502), a paper feed cassette 403 that stores recording paper onto which an image is transferred, and recording from the paper feed cassette 403 A paper feed roller 404 that feeds the paper, a registration roller 405 that feeds the recording paper at a predetermined timing, and a roller that feeds the recording paper to the transfer section of each process cartridge. A belt 406, a fixing device 409 including a fixing belt 407 and a pressure roller 408 for fixing an image transferred onto a recording sheet, a discharge roller 410 for discharging the fixed recording sheet onto a discharge tray 411, and the like. It becomes the composition.

  As shown in FIG. 24, each process cartridge 402 is composed of a drum-shaped photosensitive member 412 that is an image carrier, a charging roller 413, and a developing device according to the present invention. The apparatus 414, the cleaning blade 415, and the like are integrally provided so as to be detachable from the main body of the image forming apparatus. By providing the developing device 414 in the detachable process cartridge 402, it is possible to improve maintenance and easily replace the developing device 414 with another device.

  Further, in the developing device 414, a toner supply roller 416, a charging roller 417, a transport substrate 418, a toner feeding substrate 419 to the transport substrate 418, and a toner return roller 420 for returning the collected toner are provided. It is stored. In addition, a slit 421 serving as a window through which the laser beam from the optical writing device 401 is incident is provided on the back side of the process cartridge 402.

  Each of the optical writing devices 401-M, 401-C, 401-Y, 401-Bk is composed of a semiconductor laser, a collimating lens, an optical deflector such as a polygon mirror, a scanning imaging optical system, and the like. A laser beam modulated in accordance with image data for each color input from a host (image processing apparatus) such as a computer is emitted, and each process cartridge 402-M, 402-C, 402-Y, 402-Bk is exposed to light. The body 412 is scanned and an electrostatic charge image (electrostatic latent image) is written.

  When the image formation is started, the photosensitive members 412 of the process cartridges 402-M, 402-C, 402-Y, and 402-Bk are uniformly charged by the charging roller 413, and the optical writing devices 401-M. , 401-C, 401-Y, 401-Bk are irradiated with a laser beam corresponding to image data to form an electrostatic latent image of each color on each photoconductor.

  The electrostatic latent image formed on the photoreceptor 412 is developed and visualized with toner of each color by ETH development by the transport substrate 418 of the developing device 414. Further, the toner that has not been developed is transported by the transport substrate 418 and returned to the inlet side of the toner feeding substrate 419 by the toner return roller 420. In this way, by performing development with the developing device according to the present invention, a high-quality image can be formed as described above.

  On the other hand, the recording paper in the supply cassette 403 is fed by the supply roller 404 in synchronization with the image formation of each color of the process cartridges 402 -Bk, 402 -Y, 402 -C, and 402 -M, and is registered by the registration roller 405. The sheet is conveyed toward the transfer belt 406 at a predetermined timing. Then, the recording paper is carried on the transfer belt 406 and sequentially conveyed toward the photosensitive members 412 of the four process cartridges 402-Bk, 402-Y, 402-C, and 402-M, and Bk, Y on each photosensitive member. , C, M toner images are sequentially superimposed and transferred. The recording sheet on which the four color toner images are transferred is conveyed to the fixing device 409, where the color image composed of the four color toner images is fixed, and is discharged onto the discharge tray 411.

  Next, an image forming apparatus according to a fourth embodiment provided with a process cartridge according to another invention will be briefly described with reference to FIGS. 25 and 26. FIG. 25 is a schematic configuration diagram of an image forming apparatus provided with a process cartridge, and FIG. 26 is a schematic configuration diagram of the process cartridge.

  An image forming apparatus 500 shown in FIG. 25 includes process cartridges 502-Y, 502-M, 502-C, and 502-Bk (hereinafter referred to as “color”) along a transfer belt (image carrier) 501 extending horizontally. , A color image forming apparatus of a tandem type in which process cartridges 502 are collectively arranged. The process cartridge 502 has been described in the order of yellow, magenta, cyan, and black. However, the process cartridge 502 is not specified in this order, and may be arranged in any order.

  A process cartridge 502 shown in FIG. 26 processes a plurality of components such as the developing device 508 and the cleaning device 509 according to the present invention including the image carrier 505, the charging unit 506, and the transport substrate 507. The cartridge is integrally connected as a cartridge, and the process cartridge is configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer.

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

  In view of this, a compact and highly durable color image forming apparatus that can be replaced by the user can be provided by integrally combining at least the components of the image carrier and the developing device as the process cartridge 502.

  Here, the development toner on the image carrier 505 developed by the process cartridges 502-Y, 502-M, 502-C, and 502-Bk of each color is applied to the transfer belt 501 to which a transfer voltage that extends horizontally is applied. Sequentially transferred.

  In this way, images of yellow, magenta, cyan, and black are formed, transferred onto the transfer belt 501 in multiple layers, and transferred onto the transfer material 504 by the transfer unit 503. The multiple toner images on the transfer material 504 are fixed by a fixing device (not shown).

  Since each of the image forming apparatuses according to the above embodiments includes the developing device according to the present invention, the apparatus can be reduced in size and cost, and the image quality can be improved without toner scattering. it can.

In the above embodiment, the toner is described as an example of the powder, but the present invention can be similarly applied to an apparatus for conveying powder other than the toner. Further, although the drive signal applied to the transport electrode is described by taking three phases as an example, it may be an n phase (n is a positive integer greater than or equal to 2 ) such as a four phase or a six phase. Further, by making the transfer substrate cylindrical, the toner recovery from the transfer substrate can be reduced in size, and the utilization efficiency is improved.

  Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and substitutions can be made as long as they are described in the claims.

1 is a schematic diagram illustrating a configuration of a developing device according to an embodiment of the present invention. It is a top view of the conveyance board | substrate of the image development apparatus of this Embodiment. FIG. 3 is a cross-sectional view taken along line A-A ′ of FIG. 2. FIG. 3 is a sectional view taken along line B-B ′ in FIG. 2. FIG. 3 is a cross-sectional view taken along line C-C ′ in FIG. 2. FIG. 3 is a sectional view taken along line D-D ′ in FIG. 2. It is a wave form diagram which shows an example of the drive waveform given to a conveyance board | substrate. It is the schematic which shows the mode of conveyance and hopping of powder. It is the schematic which shows the specific example of the mode of conveyance of powder, and a hopping. FIG. 2 is a block diagram illustrating an example of a drive circuit in FIG. 1. It is a time chart which shows an example of the drive waveform of a conveyance voltage pattern and a collection | recovery conveyance voltage pattern. It is a time chart which shows an example of the drive waveform of a hopping voltage pattern. It is a time chart which shows the other example of the drive waveform of a hopping voltage pattern. It is a figure which shows the electrode width and electrode space | interval of the conveyance board | substrate of the image development apparatus of this Embodiment. It is a characteristic view which shows an example of the relationship between an electrode width and the electric field (X direction) of a 0V electrode end. It is a characteristic view which shows an example of the relationship between an electrode width and the electric field (Y direction) of a 0V electrode end. It is a characteristic view which shows an example of the relationship between the film thickness of a surface protective layer, and electric field strength. It is a figure which shows the relationship between the film thickness (5 micrometers) of a surface protective layer, and electric field strength. It is a figure which shows the relationship between the film thickness (30 micrometers) of a surface protective layer, and electric field strength. It is a schematic block diagram which shows the structure of the image forming apparatus which concerns on the 1st Embodiment based on another invention. It is a schematic block diagram which shows the structure of the image forming apparatus which concerns on the 2nd Embodiment based on another invention. It is an expansion schematic block diagram which shows the structure of the developing device of FIG. It is a schematic block diagram which shows the structure of the image forming apparatus which concerns on the 3rd Embodiment based on another invention. FIG. 24 is an enlarged schematic configuration diagram illustrating a configuration of a process cartridge including the developing device of FIG. 23. It is a schematic block diagram which shows the structure of the image forming apparatus which concerns on the 4th Embodiment based on another invention. FIG. 26 is an enlarged schematic configuration diagram illustrating a configuration of a process cartridge including the developing device of FIG. 25.

Explanation of symbols

10, 206, 314; developing device,
11, 216, 217, 330, 331, 418, 507;
12; drive circuit, 20; photosensitive drum, 21; pulse signal generation circuit,
22a to 22c, 23a to 23c; waveform amplifier, 101; support substrate,
102; Transport electrode, 103; Surface protective layer, 104; Common electrode,
105; interlayer insulating film; 106; contact hole; 107; insulating layer;
200, 300, 400, 500; image forming apparatus,
402, 502; process cartridge.

Claims (8)

A conveying member disposed opposite to the latent image carrier and having a plurality of conveying electrodes for generating a traveling wave electric field for moving the powder; and a powder supply mechanism for supplying the powder to the conveying member; A recovery mechanism for recovering excess powder that has not been used for development on the latent image carrier from the latent image carrier to the powder supply mechanism, and the powder is placed on the latent image carrier. In a developing device for developing a latent image on a latent image carrier by attaching a body,
The conveyance member includes a supply conveyance region for conveying the powder from the powder supply mechanism to the latent image carrier along the conveyance direction, and the powder conveyed to the supply conveyance region is the latent image carrier A developing area that adheres to a body to form a latent image; and a recovery conveyance area where excess powder is conveyed from the latent image carrier to the powder supply mechanism, wherein the powder is supplied and conveyed. The film thickness of the first insulating layer covering at least the surface of the transport electrode in a region other than the transport region that is transported in order through the region, the development region, and the collection transport region is at least the transport electrode in the transport region A developing device characterized in that it is thicker than the film thickness of the second insulating layer covering the surface of the film. The developing device according to claim 1, wherein the film thickness of the first insulating layer is 80 μm or more. The developing device according to claim 1, wherein the first and second insulating layers are formed by a thin film forming method. The developing device according to claim 1, wherein the first and second insulating layers are formed by a screen printing method. The developing device according to claim 1, wherein the first and second insulating layers are formed of a tape using an insulating resin.   6. A process cartridge comprising at least the developing device according to claim 1 and detachably attached to an image forming apparatus main body. In an image forming apparatus that forms an image by developing a latent image on a latent image carrier by depositing powder on the latent image carrier,
An image forming apparatus comprising the developing device according to claim 1 or the process cartridge according to claim 6. In an image forming apparatus for forming a color image,
An image forming apparatus comprising a plurality of process cartridges according to claim 6.

Images