JP2008281889A - Developing method, developing device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing method and device, whereby a stable quantity of developer attached to a latent image carrier is obtained, and to provide a process cartridge and an image forming apparatus. <P>SOLUTION: In the developing method, the development potential difference in the highest concentration developer attachment area is set so as to be greater than the potential of a layer of attached developer, which is determined by a quantity of conveyed developer. Based on a quantity of developer conveyed through a developing area, the amount of developer attached to the highest concentration developer attachment area is regulated. This decreases a change in the quantity of attached developer, caused by a change in the potential of a latent image, and obtains a stable quantity of attached developer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing method, a developing device, a process cartridge, and an image forming apparatus, and more particularly to a developing device that can obtain high developing efficiency by low voltage driving, and a process cartridge and an image forming apparatus that include the developing device.

  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.

As a conventional image forming apparatus, as described in Patent Document 1 and Patent Document 2, a superimposed voltage of DC and AC is applied between a latent image carrier and a developing roller to develop in a non-contact manner. There is also known a developing method called so-called jumping development in which toner is transferred from a roller to a latent image carrier. Further, as another conventional image forming apparatus, as described in Patent Document 3 and Patent Document 4, the electrostatic transport substrate is used to transport the toner to a position facing the latent image carrier and to vibrate. Also proposed is a method in which the toner is separated from the conveying surface by a suction force generated between the latent image carrier and the surface of the latent image carrier so as to float and smoke. As an image forming apparatus that obtains a color image by superimposing multicolor toners on a latent image carrier, a method is known in which toner is jumped from a developing roller as described in Patent Document 5. In addition, as described in Japanese Patent Application Laid-Open No. H10-260260, there is also proposed a method in which the over development is performed with the toner flying by the action of the electric field curtain. Further, as described in Patent Document 7 and Patent Document 8, a method of controlling a developing device using a traveling wave so that a sufficient developing amount is always obtained has been proposed.
JP-A-9-197781 JP-A-9-329947 Japanese Patent Publication No. 5-031146 Japanese Patent Publication No. 5-031147 Japanese Patent Publication No. 8-003673 Japanese Patent Laid-Open No. 3-021967 JP 2004-170796 A JP-A-2005-55698

  However, in an image forming apparatus having a developing device that applies toner to a latent image carrier using DC and AC applied from the developing roller and brought into a non-contact state, contact between the developing roller and the toner In order to overcome the adhesion force and make a non-contact state, it is necessary to apply a large force from the electric field. In the development area where the electrostatic latent image and the developing roller face each other, an excessive electric field necessary to make a non-contact state is applied, thereby affecting the electric field created by the latent image and causing the contamination of the scattered ground. It is also. The so-called jumping development is of this type, and since it is necessary to exchange charged toner with a high voltage, a high voltage power source is required, and there is a problem that the apparatus is increased in size and cost.

  Further, the current problem in the image forming apparatus using powder is how to satisfy image quality, cost, and environment. In terms of image quality, when forming a color image, it is how to develop one isolated dot of 1200 dpi having a diameter of only about 30 μm, and preferably develop without background smearing. In terms of cost, when considering a personal laser printer, it is important to reduce the total cost including not only the single unit cost of the developer and developer but also the maintenance and final disposal costs.

  Furthermore, in terms of the environment, it is particularly important to prevent the toner that is a fine powder from being scattered inside and outside the apparatus.

  A method proposed in view of such problems is an EH (Electrostatic Transport & Hopping) phenomenon. By using this development, a developing device capable of obtaining a high developing efficiency by low voltage driving, a process cartridge and an image forming apparatus equipped with the developing device, a low developing voltage capable of being driven by a low voltage, and a powder developing method. A developing device and a developing method capable of preventing scattering, a process cartridge and an image forming apparatus provided with the developing device, and an image forming method for performing the developing method were realized. As in the proposed EH development, the toner in the development region is already in a state where no proximity force (adhesion force due to contact) acts between the developer carrying member and the toner, so that the electric field of the latent image can be prevented. Development that reproduces faithful minute dots and does not cause background stains is possible.

  However, in such a developing device, the toner adheres to the latent image faithfully, so if there is a variation in the depth of the latent image, it is reproduced as a variation in the amount of adhesion as it is, and the stable amount control is possible. There is a problem that is difficult. In Patent Documents 7 and 8, there is described a technique for controlling so that toner sufficient to adhere to a latent image is conveyed to the development area. In this technique, the essence that the adhesion amount is determined by the latent image. Are the same, and it is difficult to stably reproduce latent image variations. Further, in an image forming apparatus that develops multiple color toners on the image carrier, the potential of the latent image varies depending on whether or not the toner is already attached on the image carrier when developing the second and subsequent colors. In this case, the amount of adhesion to the latent image changes.

  The present invention is intended to solve these problems, and an object thereof is to provide a developing method, a developing device, a process cartridge, and an image forming apparatus capable of obtaining a stable developer adhesion amount on a latent image carrier. And

  In order to solve the above problems, according to the developing method of the present invention, the developing potential difference is set so that the developing potential difference at the highest density developer adhering portion is larger than the adhesive layer potential determined by the developer transport amount. It is characterized in that the amount of the developer attached to the developer attaching portion having the highest density is regulated based on the amount of developer transporting that passes through the developing region. Therefore, the variation in the adhesion amount due to the variation in the latent image potential is reduced, and a stable developer adhesion amount can be obtained.

  Further, the development potential difference is preferably set based on the electrostatic latent image forming conditions or set based on the developer potential on the developer carrying member.

  Further, fine adjustment is possible by adjusting the amount of developer transport that passes through the development region based on the amount of developer supplied to the developer carrier.

  Further, by adjusting the developer transport amount passing through the development area based on the moving speed of the developer carrier, the developer can be adjusted independently of the electric field condition in the development area.

  Further, the developing device according to another invention includes an image carrier that carries an electrostatic latent image, and a developer carrier that is provided to face the electrostatic latent image on the image carrier so as to form a development region. An image forming apparatus that attaches a developer to an electrostatic latent image and visualizes the developer. The developer is placed in a state where no proximity force acts on the developer carrying member, and the developer is in a latent state with respect to the developer in the state. An image electric field is applied to adhere to the latent image. The developing device of the present invention has a developing potential difference setting means for setting the developing potential difference so that the developing potential difference at the highest density developer adhering portion is larger than the adhesive layer potential determined by the developer transport amount. The feature is that the amount of developer attached to the highest density developer attaching portion is regulated based on the amount of developer transport passing through the developing region. Therefore, the variation in the adhesion amount due to the variation in the latent image potential is reduced, and a stable developer adhesion amount can be obtained.

  The development potential difference setting means sets the development potential difference based on the electrostatic latent image forming conditions or the developer potential on the developer carrier.

  Furthermore, fine adjustment is possible by including a developer supply amount adjusting means for adjusting the developer transport amount passing through the development area based on the developer supply amount to the developer carrier.

  In addition, by having a developer supply amount adjustment unit that adjusts the developer conveyance amount that passes through the development region based on the moving speed of the developer carrier, it can be adjusted independently of the electric field conditions in the development region. It becomes.

  Furthermore, development is provided by having a developer conveying means including a conveying member having a plurality of electrodes for generating an electric field for hopping the developer and a voltage supply means for applying a multiphase voltage to the electrodes. It is possible to move the agent in a state in which the proximity force does not act on the agent carrier, and to simplify the configuration.

  In addition, the developer is supported on the plurality of electrodes for generating an electric field for hopping the developer by applying voltage application means for applying a multiphase voltage that forms a transport electric field for transporting the developer. While the proximity force is not applied on the body, it can be moved and the configuration can be simplified.

  Further, the developer carrying member moves, so that the developer can be independently controlled by conveying the developer.

  In addition, the adjustment can be ensured by having a detecting means for detecting the amount of developer on the developer carrying member.

  Further, a process cartridge according to another invention is characterized in that it 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 reduce the amount of adhesion due to the variation of the latent image potential, obtain a stable developer adhesion amount, and obtain a good image.

  According to another aspect of the present invention, there is provided an image forming apparatus for forming an image by attaching a developer to an electrostatic latent image on a latent image carrier to form an image, comprising the developing device or the process cartridge. There are features. Therefore, an image forming apparatus capable of forming a good image can be provided.

  Furthermore, as another invention, an image carrier that carries an electrostatic latent image and a plurality of developer carriers that are provided to face the electrostatic latent image on the image carrier so as to form a development region are provided. According to an image forming apparatus for forming a color image by sequentially depositing a plurality of color developers on an electrostatic latent image to form a color image, the process cartridge includes a plurality of the process cartridges. Therefore, an image forming apparatus capable of forming a good color image can be provided.

  According to the development method of the present invention, the development potential difference is set so that the development potential difference at the highest density developer adhesion portion is larger than the adhesive layer potential determined by the developer transport amount, and the highest density developer adhesion is achieved. The amount of developer adhering to the part is regulated based on the developer transport amount passing through the developing area. Therefore, the variation in the adhesion amount due to the variation in the latent image potential is reduced, and a stable developer adhesion amount can be obtained.

First, development characteristics when an electrostatic latent image is developed will be described.
FIG. 1 is a characteristic diagram showing typical development characteristics when an electrostatic latent image is developed. The toner present in the development area is developed in accordance with the attractive force from the latent image electric field, and the development is completed when sufficient toner is attached to fill the latent image. Therefore, when the development potential difference is taken on the horizontal axis, the toner adhesion amount is a straight line as shown in FIG. When the development potential difference changes from V1 to V2, the toner adhesion amount changes from M1 to M2. In such a development system, it can be seen that there is no development start voltage as seen in the conventional two-component development system, and the toner adheres as it is due to the electric field due to the potential difference of development. The end of development will be described with reference to FIG. 2 showing the potential on the image carrier. In FIG. 2, in order to perform negative-positive development with a negative charge polarity on the normal image carrier, the upper side is shown in a negative direction. The charging potential on the image carrier is Vd, the potential after exposure is Vl, and the developing bias is Vb. The toner facing this state is attracted to the electric field due to the potential difference (development potential difference) between Vb and Vl and adheres to the exposed portion. The attached toner potential is denoted as Vt. While the absolute value of Vt is smaller than Vb, the same attractive force acts on the toner on the agent carrier, and development stops when the toner potential Vt = Vb. Accordingly, the toner adhesion amount varies linearly depending on the value of Vb−Vl. FIG. 3 shows a potential state on the latent image carrier when developing the second color toner. The image bearing member is charged to Vd, and a portion where the first color toner is not attached under the same conditions and a portion where the first color toner is already attached are exposed. At this time, the latent image of the portion where the toner is already attached becomes shallower than the portion where the toner is not attached, and becomes Vlt. This is due to the difference in potential due to the already-attached toner, the exposure amount due to the toner shielding effect, and the like. In this state, a difference occurs in the development potential difference between the toner adhering portion and the non-adhering portion, and therefore, the toner adhering amount of both is different. Here, considering the development characteristics with Vb-Vlt being V1 and Vb-Vl being V2, there is a difference between M1 and M2 as shown in FIG.

  In contrast, let us consider adjusting the development characteristics as shown in FIG. With respect to the development potential difference, the toner adhesion amount reaches a certain value, and by setting V1 and V2 within this range, it is possible to suppress the change in the adhesion amount with respect to the development potential difference change, and the toner adhesion on the latent image carrier. A stable toner adhesion amount can be obtained regardless of the state. Specifically, this can be realized by regulating the amount of developer that passes through the development area during the development time.

  The amount of developer that passes through the development area during the development time is expressed by the product of the toner amount per unit area of the agent carrier and the moving speed. When the moving speed is constant, the toner amount per unit area of the agent carrier is the supply amount, and the supply amount is controlled with controllability depending on the supply characteristics from the supply member to the agent carrier, and the development area is developed. The amount of toner passing during the time can be controlled. When the moving speed is changed, the amount of developer passing through the developing area during the developing time can be increased or decreased in proportion to the moving speed. When controlled by the moving speed, it has the advantage of good quantification because it can be linearly increased / decreased with respect to the speed change, but the relative speed with respect to the movement of the image carrier of the toner passing the developing area changes, and the development characteristics May be affected. In the case of controlling by the supply amount, it is affected by the sensitivity depending on the method used for the supply, but the degree of freedom of control is increased by being changed independently of the development characteristics.

  FIG. 5 is a diagram showing a state of potential. Assuming that the solid density portion has the highest density, the development potential difference at this time is represented by Vb−Vl. When the toner limited to the desired adhesion amount by the toner conveyance amount adheres to the latent image in this potential state. When the toner layer potential is Vtmax, a stable solid adhesion amount can be obtained by setting Vb−Vl to be larger than Vtmax. Since the development potential difference changes according to Vl determined by the charging potential Vd of the latent image carrier and the exposure energy, the above-described state can be obtained by adjusting the latent image carrier charging potential and the exposure energy.

  Similarly, the above state can be obtained by adjusting the developing bias Vb. Regarding the setting of Vb, which is the condition on the agent carrier, the average value of the voltage applied to the agent carrier may be simply set as Vb. It is also possible to measure the potential when the toner hops on the agent carrier and to control the potential as Vb, so that more reliable control can be performed. In this case, the means for measuring the potential on the image carrier shown in FIG. 1 is effective.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 6 is a schematic configuration diagram showing a configuration of a developing device according to an embodiment of the present invention. A developing device 10 according to the present embodiment shown in the figure is a developing device using a two-component developer composed of a magnetic carrier and a nonmagnetic toner, and includes an image carrier 11 on which an electrostatic latent image is formed, and an image carrier. A toner conveying member 12 formed in a roller shape that conveys toner to a facing region 11, and a developer carrier 13 that is a toner supply unit that is opposed to the toner conveying member 12 and supplies toner to the toner conveying member 12. And a developer accommodating portion 14 that accommodates the toner and magnetic carrier supplied by the developer carrier 13. In this case, the toner conveying member 12 is disposed so as to face the image carrier 11 and the developer carrier 13 in a region opposite to the radial direction.

  The toner conveying member 12 and the image carrier 11 face each other in a non-contact manner with a gap of 50 to 1000 μm, preferably 150 to 400 μm. Further, the toner conveying member 12 rotates in the direction of arrow A. It is also possible to apply a voltage so that the toner is transported on the outer peripheral surface in the direction of arrow A by a transport electric field (phase-shift electric field). On the other hand, the developer carrier 13 rotates in the direction of arrow B.

  The developer accommodating portion 14 is divided into two chambers, and each chamber communicates with a developer passage (not shown) at both ends in the developing device. Two-component developer is accommodated in the developer accommodating portion 14 and is conveyed through the developer accommodating portion 14 while being agitated by the agitating and conveying screws 15a and 15b in the respective chambers.

  The developer container 14 is provided with a toner supply port 16 for supplying developer from a toner container (not shown). The developer container 14 is provided with a toner concentration sensor (not shown) for detecting the magnetic permeability of the developer, and detects the concentration of the developer. When the toner concentration in the developer accommodating portion 14 decreases, the toner is replenished from the toner replenishing port 16 to the developer accommodating portion 14.

  Further, the developer carrier 13 is disposed in a region of the developer container 14 that faces the agitating and conveying screw 15a. A fixed magnet is disposed inside the developer carrier 13, and the developer in the developer container 14 is pumped up to the surface of the developer carrier 13 by the rotation and magnetic force of the developer carrier 13. It is done.

  Further, development is performed in a region facing the developer carrier 13 on the downstream side in the rotation direction of the developer carrier 13 (in the direction of arrow B) from the developer pumping region and upstream from the region facing the toner conveying member 12. A developer layer regulating member 17 is provided, and the developer pumped in the pumping area is regulated to a certain amount of developer layer thickness. Then, the developer passing through the developer layer regulating member 17 is transported to a region facing the toner transport member 12 as the developer carrier 13 rotates.

  Here, a supply bias is applied to the developer carrier 13 by the first voltage application means 18. Further, a voltage is applied to the electrode of the toner conveying member 12 by the second voltage applying means 19.

  Thus, in the region where the developer carrier 13 and the toner carrying member 12 face each other, an electric field is generated between the toner carrying member 12 and the developer carrier 13 by the first and second voltage applying units 18 and 19. ing. Under the electrostatic force from the electric field, the toner dissociates from the carrier and moves to the surface of the toner transport member 12.

  Next, the toner transported to the region facing the image carrier 11 as the toner transport member 12 rotates causes the image carrier to develop by the developing electric field between the toner transport member 12 and the image portion on the image carrier 11. The latent image on the image carrier 11 is visualized (developed) by moving onto the body 11. A surface potential measuring unit 20 for detecting the surface potential on the conveying member is provided facing the conveying member. The surface potential of the transport member in a state where the transport voltage is applied to the electrode on the transport member varies depending on the transport voltage and the state of the toner being transported. By measuring and detecting the surface potential directly by the surface potential measuring unit 20, it is possible to know the accurate potential on the conveying member.

  The developing device according to the present embodiment has a configuration such as two-component development in which a toner is charged using a carrier and then supplied to a toner conveying member. However, the toner is charged by friction with a roller and a blade without using a carrier. It is also possible to adopt a configuration such as one-component development that supplies the toner to the toner conveying member. Further, since the development amount is determined by the toner conveyance amount on the developer carrier, it is also important to directly measure the toner conveyance amount on the agent carrier. This is possible by providing a reflection type photosensor or the like on the surface of the developer carrying member.

  Here, the configuration of the transport substrate in the developing device of this embodiment will be described in detail with reference to FIGS. 7 is a plan view of the transfer substrate, FIG. 8 is a cross-sectional view taken along the line AA ′ in FIG. 7, FIG. 9 is a cross-sectional view taken along the line BB ′ in FIG. FIG. 11 is a sectional view taken along the line DD ′ of FIG.

  The transport substrate 100 in the developing device of this embodiment is a set of three transport electrodes 102a, 102b, and 102c (these are 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. 8 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. 7, 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. 9, the pattern of the common electrodes 104a, 104b, and 104c 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 a drive circuit (not shown). 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, Bn, and W can be used. In particular, since the charge amount of the charged toner tends to decrease in the middle of conveyance when the surface hydroxyl groups increase, inorganic nitride compounds with few surface hydroxyl groups (SiOH, silatol groups) are preferable.

  Next, the principle of electrostatic transport of toner on the transport substrate 100 configured as described above will be described. By applying an n-phase driving waveform to the plurality of transport electrodes 102 of the transport substrate 100, 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 100 is In response to the repulsive force and / or suction force, it moves in the transfer direction including hopping and conveyance.

  For example, for a plurality of transport electrodes 102 of the transport substrate 100, as shown in FIG. 12, A (three-phase pulse drive waveform (drive signal) A (drive signal) changing between ground G (0V) and positive voltage +. A phase), B (B phase), and C (C phase) are applied at different timings.

  At this time, as shown in FIG. 13, there is negatively charged toner T on the transport substrate 100, 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 FIG. In FIG. 3, a repulsive force acts between the left “G” transport electrode 102 and a suction force acts between the right “+” transport electrode 102. “+” Moves toward the transport electrode 102. Further, as shown in FIG. 13 (3), “G”, “+”, “G”, “G”, and “+” are applied to the plurality of transport electrodes 102 at the next timing, respectively, and negatively charged. Similarly, since the repulsive force and the attractive force act on the toner T, the negatively charged toner T further moves toward 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 100, 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.

  The state of the toner T transport will be described in detail with reference to FIG. 14. As shown in FIG. 14A, the transport electrodes A to F of the transport substrate 100 are all at 0V (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 100 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.

  FIG. 15 is a schematic cross-sectional view showing the configuration of a substrate when toner hopping development is performed by applying a two-phase voltage. A pattern electrode 202 is formed on the base substrate 201 and is protected by the surface protective layer 203. Suitable material properties for each layer are similar to a three-phase substrate. A two-phase voltage is applied to the electrodes by the voltage applying means 204. When the electric field between the adjacent electrodes is reversed, the toner 205 adhering to the substrate as shown in FIG. 15A is hopped as shown in FIG. 15B and contacts the substrate in the development region. It will be in the state where adhesive force by does not arise. In the case of two phases, since the toner is not transported by the electric field, it is essential to move the substrate in the development area, and it is preferable to form a sleeve as shown in FIG.

Next, an example of the image forming apparatus according to the present invention including the process cartridge according to the present invention will be described with reference to FIG.
The image forming apparatus 300 includes an image carrier, a charging unit, a developing unit according to the present invention as a developing unit, and an image forming unit including a cleaning unit, black (K), magenta (M), cyan (C), Process cartridges 301K, 301M, 301C, and 301Y that form yellow (Y) toner images (hereinafter simply referred to as “process cartridge 301” when not distinguished from each other; the same applies to others), and optical writing devices 302K and 302M. 302C, 302Y, a transfer belt 303a for transferring the transfer material 306, transfer rollers 303Bk, 303Bm, 303Bc, 303By facing the process cartridges 301K, 301M, 301C, 301Y with the transfer belt 303a interposed therebetween, a fixing device 304, And a paper feeding device 305 for accommodating the transfer material 306. To have.

  Here, the optical writing devices 302K, 302M, 302C, and 302Y are for writing a latent image on the charged image carrier of the process cartridges 301K, 301M, 301C, and 301Y in accordance with image information, and optical scanning using polygons. Various devices such as devices and LED arrays can be used.

  The conveyor belt 303 a is stretched between the conveyor roller 307, the driven roller 308, and the tension rollers 309 and 310, and moves around in the direction of the arrow by the rotation of the conveyor roller 307. An adsorption roller 311 for adsorbing the transfer material 306 onto the conveyance belt 303a is disposed opposite the conveyance roller 307, and a pattern when a toner image is formed on the conveyance belt 303a on the exit side of the conveyance belt 303a. A P sensor 312 for detecting the above is disposed.

The transfer rollers 303Bk, 303Bm, 303Bc, and 303By have at least a core metal and a conductive elastic layer that covers the core metal, and the conductive elastic layer is an elastic material such as polyurethane rubber or ethylene-propylene-diene polyethylene (EPDM). In addition, an elastic roller in which a conductivity imparting agent such as carbon black, zinc oxide or tin oxide is blended and dispersed to adjust the electric resistance value (volume resistivity) to a medium resistance of 10 ⁶ to 10 ¹⁰ Ω · cm.

  The fixing device 304 includes a heating roller 304a and a pressure roller 304b facing the heating roller 304a.

  In the image forming apparatus 300, in a normal image forming operation, the transfer material 306 such as a recording sheet supplied from the sheet feeding device 305 is a transfer body that is a transfer body when a predetermined voltage is applied to the suction roller 311. Adsorbed to the material conveying belt 303a. The transfer material 306 moves together with the transfer material conveyance belt 303a while being carried on the transfer material conveyance belt 303a. During the movement, the toner images of the respective colors are sequentially transferred from the process cartridges 301K, 301M, 301C, and 301Y. A color toner image is formed thereon. When the transfer material 306 passes through the conveying belt 303a and reaches the fixing device 304, the toner image on the transfer material 306 is heated while being sandwiched between the heating roller 304a and the pressure roller 304b to be fixed on the transfer material 306. As a result, a visible image is fixedly formed on the transfer material 306. Thereafter, the transfer material 306 on which the color image is formed is discharged to a paper discharge unit 313 at the top of the apparatus main body.

<Experimental example 1>
Using the developing device shown in FIG. 6, development was performed by applying a two-phase voltage and rotating the agent carrier 2 in the direction of the arrow. Table 1 shows the experimental conditions and results examined.

As can be seen from this result, the linear velocity of the agent carrier and the linear velocity of the photosensitive member are constant, so that when the development potential difference is sufficiently large with respect to the amount of toner on the image carrier, it is stable against fluctuations. Development is possible. This indicates that image formation is performed at V1 and V2 as shown in FIG. At this time, the amount of toner that moves in the development area during the development time is the product of the moving speed and the amount of toner adhering to the agent carrier, so that the ratio of the linear velocity of the agent carrier to the photoreceptor is, for example, 2. In this case, the same result is obtained under the condition that the toner amount on the image carrier is approximately ½, but the amount of adhesion tends to be slightly reduced due to the influence on the development by the linear speed ratio. As a method of changing the amount of toner that moves in the development area during the development time, instead of changing the moving speed, the supply condition to the image carrier is changed. When the applied voltage to the supply roller is taken as a difference from the average value of the applied voltage of the agent carrier, the relationship of the supply amount to the applied voltage is as shown in FIG. The voltage applied to the supply roller is Vpp 1.2 kV and 3 kHz AC superimposed. The potential difference for obtaining an adhesion amount of 0.5 mg / cm ² is about 350 V. By adjusting the potential difference, it was possible to control the adhesion amount on the image carrier according to FIG. According to this method, it is possible to control the amount of toner that moves in the development area during the development time without affecting the development characteristics in the development area.

<Experimental example 2>
An experiment was carried out in which a toner layer was developed on a photoconductor. First, the photosensitive member was charged, exposed and developed to form an image with an adhesion amount of 0.5 mg / cm ² . The experiment was conducted with the development condition of the second color set to 1 as the linear velocity ratio between the agent-carrying member and the photosensitive member. The supply roller bias was set and controlled so that the toner amount on the agent carrier was about 0.55 mg / cm ² . On the other hand, in the condition 1, the photosensitive member charging potential was -200V, and the developing bias was -135V. The result is shown in FIG. In Condition 2, the photosensitive member charging potential was −250 V, and the developing bias was −185 V. The result is shown in FIG. The vertical axis is the amount of toner attached to the second color, and it is a diamond-shaped plot with the data attached to the part where the toner is already attached. Shown in the plot. In FIG. 18, most of the plots show the development potential difference in a range where the amount of adhesion is limited by the amount of agent transport, and the amount of toner adhesion varies depending on whether or not the toner adheres to the photoreceptor during the second color development. Not. On the other hand, in FIG. 19, when the second color is developed, the adhesion amount of the portion where the toner is already adhered is smaller than that of the portion where the toner is not present, and a good image cannot be obtained. As described above, the latent image formation condition is such that the image formation is performed in an area where the adhesion amount is limited by the amount of movement of the agent in the development area. Is obtained.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and substitutions are possible as long as they are described within the scope of the claims.

FIG. 10 is a characteristic diagram showing typical development characteristics when an electrostatic latent image is developed. It is a figure which shows the electric potential on the image carrier in the completion | finish of an image. FIG. 6 is a diagram illustrating a potential state on a latent image carrier when developing a second color toner. FIG. 7 is a characteristic diagram illustrating a relationship between a development potential difference in which development characteristics are adjusted and a toner adhesion amount. It is a figure which shows the state of an electric potential. 1 is a schematic configuration diagram illustrating a configuration of a developing device according to an embodiment of the present invention. It is a top view of a conveyance board. FIG. 8 is a cross-sectional view taken along line A-A ′ of FIG. 7. FIG. 8 is a sectional view taken along line B-B ′ of FIG. 7. FIG. 8 is a cross-sectional view taken along line C-C ′ of FIG. 7. FIG. 8 is a sectional view taken along line D-D ′ in FIG. 7. It is a wave form diagram which shows an example of the drive waveform given to a conveyance board | substrate. FIG. 3 is a schematic diagram illustrating toner conveyance and hopping. FIG. 6 is a schematic diagram illustrating a specific example of toner conveyance and hopping. It is a schematic sectional drawing which shows the structure of the board | substrate in the case of toner hopping development by application of a two-phase voltage. 1 is a schematic cross-sectional view illustrating an example of an image forming apparatus according to the present invention including a process cartridge according to the present invention. 6 is a characteristic diagram illustrating a relationship of a toner adhesion amount with respect to a supply potential difference in Experimental Example 1. FIG. FIG. 10 is a characteristic diagram illustrating a relationship between a toner adhesion amount and a development potential difference in Condition 1 of Experimental Example 2. FIG. 10 is a characteristic diagram illustrating a relationship between a toner adhesion amount and a development potential difference in Condition 2 of Experimental Example 2.

Explanation of symbols

100; transfer substrate; 101; support substrate; 102; transfer electrode;
103; surface protective layer; 104; common electrode; 105; interlayer insulating film;
106; contact hole, 107; insulating layer.

Claims (17)

An image carrier that carries an electrostatic latent image, and a developer carrier that is provided to face the electrostatic latent image on the image carrier so as to form a development region. An image forming apparatus that attaches to an image and visualizes the developer, wherein the developer is brought into a state in which a proximity force does not act on the developer carrying member, and a latent image electric field is acted on the developer in the state to perform the static In the developing method of attaching a developer to the electrostatic latent image,
The development potential difference is set so that the development potential difference at the highest density developer adhesion portion is larger than the adhesive layer potential determined by the developer transport amount, and the developer adhesion amount to the highest density developer adhesion portion is A developing method characterized by regulating based on a developer conveyance amount passing through a developing region.   2. The developing method according to claim 1, wherein the developing potential difference is set based on an electrostatic latent image forming condition.   2. The developing method according to claim 1, wherein the developing potential difference is set based on a developer potential on the developer carrying member.   The developing method according to claim 1, wherein a developer transport amount that passes through the developing region is adjusted based on an amount of developer supplied to the developer carrying member.   The developing method according to claim 1, wherein a developer transport amount passing through the developing region is adjusted based on a moving speed of the developer carrier. An image carrier that carries an electrostatic latent image, and a developer carrier that is provided to face the electrostatic latent image on the image carrier so as to form a development region. An image forming apparatus that attaches to an image and visualizes the developer, wherein the developer is brought into a state where a proximity force does not act on the developer carrying member, and a latent image electric field is applied to the developer in the state to form a latent image. In the developing device to be attached,
Development potential difference setting means for setting the development potential difference so that the development potential difference at the highest density developer adhering portion is larger than the adhesive layer potential determined by the developer transport amount, with respect to the highest density developer adhering portion. A developing device that regulates a developer adhesion amount based on a developer conveyance amount passing through a development region.   7. The developing device according to claim 6, wherein the developing potential difference setting means sets the developing potential difference based on an electrostatic latent image forming condition.   7. The developing device according to claim 6, wherein the developing potential difference setting means sets the developing potential difference based on a developer potential on the developer carrying member.   The developer supply amount adjusting means for adjusting a developer transport amount passing through the development region based on a developer supply amount to the developer carrying member. The developing device according to item.   9. The development according to claim 6, further comprising a developer supply amount adjusting unit that adjusts a developer conveyance amount passing through the development region based on a moving speed of the developer carrying member. apparatus.   A developer conveying unit including a conveying member having a plurality of electrodes for generating an electric field for hopping the developer and a voltage supply unit for applying a multiphase voltage to the electrodes. The developing device according to claim 6.   11. A voltage applying means for applying a multi-phase voltage that forms a transport electric field for transporting a developer to a plurality of electrodes for generating an electric field for hopping the developer. The developing device according to any one of the above.   The developing device according to claim 6, wherein the developer carrying member is transported to move the developer.   The developing device according to claim 6, further comprising a detecting unit configured to detect a developer amount on the developer carrying member.   15. A process cartridge comprising at least the developing device according to any one of claims 6 to 14 and detachable from an image forming apparatus main body. In an image forming apparatus that forms an image by attaching a developer to an electrostatic latent image on a latent image carrier to form an image,
An image forming apparatus comprising the developing device according to claim 6 or the process cartridge according to claim 15. An image carrier that carries an electrostatic latent image, and a plurality of developer carriers that are provided to face the electrostatic latent image on the image carrier so as to form a development region. In the image forming apparatus for forming a color image by sequentially attaching to the electrostatic latent image to form a color image,
An image forming apparatus comprising a plurality of process cartridges according to claim 15.

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