JP2007241006A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, a process cartridge, and an image forming apparatus which allow the reduction of scattering powder during carrying by using ETH phenomenon. <P>SOLUTION: In the developing device, a multiphase voltage is applied to carrying electrodes through common electrodes by a voltage supply means to form a carrying electric field and powder is carried to an area facing a latent image carrier by the carrying electric field, of a carrying member to stick the powder onto the latent image carrier, whereby a latent image on the latent image carrier is developed. In this developing device, space intervals between common electrodes and one ends of carrying electrodes are longer than intervals of carrying electrodes, so that toner is made to go inward in a lengthwise direction by forming an electric field gong inward. Therefore, scattering powder in the lengthwise direction can be prevented and the powder can be prevented from sticking to the common electrodes. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device, a process cartridge, and an image forming apparatus, and more specifically, using an ETH (Electrostatic Transport & Hopping) phenomenon, the distance between the transport electrodes and the distance to the common electrode are controlled to control the scattered toner being transported. The present invention relates to a developing device capable of reducing toner adhesion on a common electrode, 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 electrodes 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.
In the conventional image forming apparatus, toner is hopped during conveyance, but the direction is not necessarily constant. It is rather in the direction of spreading depending on the resistance of air and the direction of the electric field. When the conveyance direction is widened, it spreads on the common electrode where a traveling wave cannot be formed, and further to the outer edge portion in the longitudinal direction, and in the worst case, the toner is scattered in the image forming apparatus.
Further, since traveling waves are generated in the electrodes, most of the toner travels in the traveling direction according to the electric field. However, at the edge portion of the electrode, the portion to which the next electric field is applied becomes small, so that toner is generated in the direction of the common electrode. Since the toner is attracted by the Coulomb force generated by the electric field, the direction of the electric field may be limited so that the force does not go outward in the longitudinal direction.

  The present invention is for solving these problems, and provides a developing device, a process cartridge, and an image forming apparatus capable of reducing scattered powder during conveyance using an ETH (Electrostatic Transport & Hopping) phenomenon. For the purpose.

  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, the developing device of the present invention is arranged to face the latent image carrier, and to generate a traveling wave electric field for moving the powder, a plurality of arranged at predetermined intervals. A conveying member having a conveying electrode; voltage supply means for applying a multiphase voltage to the conveying electrode via a common electrode connected to one end of the conveying electrode; and a powder for supplying powder to the conveying member Supply means and recovery means for recovering excess powder are provided. In the developing device of the present invention, the voltage supply means applies a multiphase voltage to the transport electrode via the common electrode to form a transport electric field, and the transport member is a region facing the latent image carrier by the transport electric field. Then, the powder is conveyed to adhere the powder onto the latent image carrier to develop the latent image on the latent image carrier. Furthermore, the developing device of the present invention is characterized in that the gap between one end of the common electrode and the transport electrode is larger than the distance between the transport electrodes. Therefore, since the toner can be directed inward in the longitudinal direction by forming an electric field directed inward, it is possible to prevent scattered powder in the longitudinal direction and adhesion of powder on the common electrode. .

  Further, the angle formed between the arrangement direction of the transport electrodes corresponding to the area other than the development area opposite to the latent image carrier and the arrangement direction of the common electrodes is set to an acute angle with respect to the powder transport direction, thereby moving inward. The force becomes larger than the outward force, and the powder does not scatter outside.

  In addition, since the length of one end of the transport electrode is smaller than the gap interval in the transport electrode other than the development region, the inward force is larger than the outward force, and the powder is scattered outside. Disappear.

  In addition, since the length of one end of the transport electrode is larger than the electrode pitch of the transport electrode, the force toward the inner side is larger than the force toward the outer side, so that the powder is outside. Will not scatter.

  Furthermore, a process cartridge according to another invention includes at least one of the developing device described above and at least one of a latent image carrier, a charging unit, and a cleaning unit in an electrophotographic process, and is detachable from an image forming apparatus main body. is there. Therefore, it is possible to provide a process cartridge that can reduce the amount of scattered powder during conveyance.

  Furthermore, an image forming apparatus as another invention includes the developing device or the process cartridge. Therefore, it is possible to provide an image forming apparatus capable of reducing scattered powder during conveyance.

  In addition, according to another image forming apparatus, a plurality of the process cartridges can be provided to form a high-quality multicolor image, and the amount of scattered powder during conveyance can be reduced.

  In the developing device of the present invention, the gap between the common electrode and one end of the transport electrode is larger than the distance between the transport electrodes, so that the scattered powder during transport can be reduced.

  FIG. 1 is a schematic view showing the configuration of the developing device 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. For each of the eleven transport electrodes 102, different drive waveforms Va1, Vb1, n-phase (n is a positive integer of 2 or more, here three-phase) for generating a required electric field from the drive circuit 12. Vc1 and Va2, Vb2, and Vc2 are applied. 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 developing area for forming a toner image by attaching the toner T to the latent image on the photosensitive drum 20, and after passing through the developing area for collecting the toner T on the conveying substrate 11 side. Divided into collection 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 of the present invention 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 of the present invention is a set of three transport electrodes 102a, 102b, 102c (collectively referred to as the transport electrode 102) on the support substrate 101 of FIG. These are repeatedly formed and arranged at predetermined intervals along the toner conveying direction in the direction of the arrow and in a direction substantially perpendicular to the toner conveying direction to form an insulating conveying surface forming member on which a conveying surface is formed. A surface protective layer 103 made of an inorganic or organic insulating material, which is a protective film covering the surface of the electrode 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.

  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 (n is a positive integer of 2 or more) driving waveform to the plurality of transport electrodes 102 of the transport substrate 11, a phase-shift electric field (traveling wave electric field) is generated by the plurality of transport electrodes 102. The charged toner on the transport substrate 11 receives a repulsive force and / or suction force and moves in the transport direction including hopping and transport.

  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 is generated 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.

  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 of each phase to the respective transport electrodes 102 in the transport region and the 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. 11 or FIG. 12, 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. 12, when the non-image portion potential on the latent image carrier is lower than −100 V, the image portion In contrast, the toner is directed to the latent image carrier, and the toner is directed to the side opposite to the latent image carrier for the non-image portion. 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, if 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 photoreceptor, in the case of negatively charged toner, at least the potential for charging the photoreceptor is -300 V or less, or the development efficiency 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, by setting the average value (average potential) of the potential applied to the transport electrode of the transport substrate to a potential between the potential of the latent image carrier image portion and the non-image portion potential, 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.

  The strength of the electric field shown in FIGS. 14 and 15 is the value of the representative point on the surface of the transport electrode. The representative point TEa of the transport electric field TE is a point 5 μm above the end of the electrode shown in FIG. The representative point HEa is a point 5 μm above the center of the electrode shown in FIG. 13 and corresponds to the representative point having the strongest electric field acting on the toner in the X direction and Y direction, respectively.

  From FIGS. 14 and 15, the electric field capable of imparting a force acting on the toner conveyance and hopping is (5E + 5) V / m or more, and the preferable electric field having no 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.

  Further, regarding the electrode spacing R of the transport electrodes, the electric field strength in the transport direction decreases as the spacing increases, and therefore the value corresponding to the range of the electric field strength is the same. It is 1 to 20 times, preferably 2 to 10 times, and more preferably 2 to 6 times.

  Next, as shown in FIG. 2, when the common electrode is on both sides of the transport electrode, the toner may adhere to the common electrode portion, and the direction on which the electric field is applied is not constant on the common electrode. Since the electric field is not continuously formed as in the region, the adhered toner is accumulated.

  Therefore, according to the present invention, it is possible to prevent toner from adhering to the common electrode by forming a gap larger than the electrode interval of the transport electrode between the end of the transport electrode and the common electrode.

  FIG. 16 is a partially enlarged view showing the configuration of the transport electrode and the common electrode of the developing device according to the embodiment of the present invention. FIG. 17 is a plan view showing the configuration of the transport substrate in the developing device of this embodiment. In FIG. 16, the larger the gap distance D1 between the transport electrode 102a and the common electrode 104b, or between the transport electrode 102b and the common electrode 104c, the more effective, but if it is wider than the space width S that is the distance between the transport electrodes, Ideally, toner does not adhere to the common electrodes 104b and 104c. However, in reality, since the electrode surface is not a complete elastic collision, as shown in FIG. 14, when the space width S that is the distance between the transfer electrodes is set to 30 μm, the transfer electrode 102a and the common electrode 104b, or the transfer electrode It is desirable that the gap width D1 between 102b and the common electrode 104c be about three times 100 μm or more.

  In this way, the electric field strength contributing to the transfer can be different between the transfer region and other regions, and the electric field strength of the surface in the direction to be transferred becomes larger than the electric field strength of the surface of the region with the insulating layer, and the transfer is desired. Directional force increases. Therefore, the charged toner moves in the transport direction.

  Next, FIG. 18 is a partially enlarged view showing the configuration of the transport electrode and the common electrode of the developing device according to another embodiment of the present invention. The developing device of another embodiment shown in the figure has a common electrode 104a to the transport electrode 102a, a common electrode 104b to the transport electrode 102b, and a common electrode 104c to the transport electrode 102c in the toner transport direction, respectively. By applying a predetermined angle θ (θ <90 °), the direction of the electric field is directed inward in the longitudinal direction to prevent the toner from being directed onto the common electrodes 104a, 104b, 104c. The toner can be prevented from adhering to 104b and 104c. Further, as shown in FIG. 18, the length D2 of the electrode that is larger than the development width not connected to the common electrode 104b is set to be larger than the gap width D1 that is the distance between the transport electrode 102a and the common electrode 104b or the transport electrode 102c and the common electrode 104b. Also make it smaller. The force toward the inside becomes larger than the force toward the outside, and the toner is not scattered outside. At this time, the gap width D1 was set to 200 μm, and the length D2 of the electrode larger than the developing width not connected to the common electrode 104b was set to 100 μm. In this way, it is possible to prevent toner from adhering to the common electrode 104b by increasing the force of the electric field in the transport direction and decreasing the force in the direction of the outer common electrode 104b. Note that D1 '> D2' is also set for the common electrode 104c.

  Even if the toner used is indefinite, such as pulverized toner, it can prevent the toner from scattering or adhering to the common electrode, but the surface shape can be reduced by using a spherical toner with a circularity of 96% or more. Can be reduced compared with an irregular shaped toner such as pulverized toner, so that more uniform conveyance is possible. That is, when the circularity is lower than 96%, the direction of repulsion when the toner collides with the substrate becomes random, and toner deviating from the transport direction is generated, so the distances D1 and D1 ′ to the common electrode are increased. However, by defining the circularity in this way, it is possible to prevent the toner from escaping to the common electrode portion at a relatively small distance. Similarly, by setting the average roughness (Ra) representing the surface property of the substrate to be equal to or smaller than the toner diameter, when the toner collides with the substrate, the direction of rebounding is stabilized, and the movement according to the electric field is performed. Therefore, it is possible to prevent the toner from escaping to the common electrode as described above. As described above, the distance to the common electrode can be shortened, and the developing device can be downsized by shortening the longitudinal direction.

  According to the present invention, 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, positively charged. In this case, when the pressure was +3 to +40 μC / g, more preferably +10 to +30 μC / g, the transport and hopping by the electrode configuration described above could be efficiently performed.

  As a result, as described above, when the 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 toner 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, 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. 21, the developing device 314 in FIG. 20 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 having a process cartridge according to another invention will be briefly described with reference to FIGS. FIG. 22 is a schematic configuration diagram of an image forming apparatus provided with a process cartridge, and FIG. 23 is a schematic configuration diagram of the process cartridge.

  An image forming apparatus 400 shown in FIG. 22 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. 23, each process cartridge 402 is composed of four process cartridges. Each process cartridge 402 includes a drum-shaped photosensitive member 412 that is an image carrier in a case, 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.

  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, and 401-Bk includes a semiconductor laser, a collimator 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 having a process cartridge according to another invention will be briefly described with reference to FIGS. 24 is a schematic configuration diagram of an image forming apparatus provided with a process cartridge, and FIG. 25 is a schematic configuration diagram of the process cartridge.

  An image forming apparatus 500 shown in FIG. 24 has process cartridges 502-Y, 502-M, 502-C, and 502-Bk (hereinafter referred to as “process cartridges”) of respective colors 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. 25 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 developing toner on the image carrier 505 developed with the process cartridges 502-Y, 502-M, 502-C, and 520-Bk for 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 transport substrate cylindrical, the toner recovery from the transport 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 of the present invention. It is a top view of the conveyance board | substrate of the image development apparatus of this invention. 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. 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 invention. 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. FIG. 4 is a partially enlarged view showing a configuration of a transport electrode and a common electrode of a developing device according to an embodiment of the present invention. It is a top view which shows the structure of the conveyance board | substrate in the image development apparatus of this Embodiment. It is the elements on larger scale which show the structure of the conveyance electrode and common electrode of the developing device which concerns on the other embodiment of this invention. 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. 23 is an enlarged schematic configuration diagram showing a configuration of a process cartridge including the developing device of FIG. 22. It is a schematic block diagram which shows the structure of the image forming apparatus which concerns on the example of 4th Embodiment based on another invention. FIG. 25 is an enlarged schematic configuration diagram illustrating a configuration of a process cartridge including the developing device of FIG. 24.

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-22c, 23a-23c; waveform amplifier,
101; Support substrate, 102; Transport electrode, 103; Surface protective layer,
104; common electrode; 105; interlayer insulating film; 106; contact hole;
200, 300, 400, 500; image forming apparatus,
402, 502; process cartridge.

Claims (7)

In order to generate a traveling-wave electric field that is disposed opposite to the latent image carrier and moves the powder, a transport member having a plurality of transport electrodes arranged at predetermined intervals is connected to one end of the transport electrode. Voltage supply means for applying a multiphase voltage to the transport electrode via the common electrode, powder supply means for supplying the powder to the transport member, and recovery means for recovering excess powder A region where a multi-phase voltage is applied to the transport electrode via the common electrode by the voltage supply means to form a transport electric field, and the transport member is a region facing the latent image carrier by the transport electric field A developing device for transporting the powder to the latent image carrier and developing the latent image on the latent image carrier by attaching the powder onto the latent image carrier;
The developing device according to claim 1, wherein a gap between one end of the common electrode and the transport electrode is larger than a distance between the transport electrodes.   The angle formed by the arrangement direction of the transport electrodes and the arrangement direction of the common electrodes corresponding to an area other than the development area facing the latent image carrier is an acute angle with respect to the powder transport direction. Development device.   3. The developing device according to claim 1, wherein the transport electrode is a region other than the development region, and a length of one end of the transport electrode is smaller than the gap interval.   The developing device according to claim 1, wherein the transport electrode is a region other than the development region, and a length of one end of the transport electrode is larger than an electrode pitch of the transport electrode.   5. The image forming apparatus main body includes at least one of the developing device according to claim 1 and at least one of a latent image carrier, a charging unit, and a cleaning unit in an electrophotographic process, and is detachable from an image forming apparatus main body. Process cartridge characterized by. 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 5. In an image forming apparatus for forming a color image,
An image forming apparatus comprising a plurality of process cartridges according to claim 5.

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