JP2013205616A - Developing device, image forming apparatus and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of stably preventing scumming due to poorly charged toner even in the lapse of time in a developing device equipped with a flare developing system, an image forming apparatus and a process cartridge equipped with the developing device.SOLUTION: There is provided a developing device 6 equipped with a flare developing system, which comprises: a toner collecting roller 31 of which surface moves endlessly in a moving direction of a toner bearing roller 7 as a toner collecting member in which a supply roller 62 faces the outer peripheral surface of the toner bearing roller 7 at a position of the downstream side from the supply position for supplying toner to the toner bearing roller 7 and the upstream side from the developing area and which collects the reversely charged toner contained in toner in a hopping state; and a collecting roller cleaning blade 32 for mechanically removing the poorly charged toner containing the reversely charged toner conveyed by the endless movement of the toner collecting roller 31 from the surface of the toner collecting roller 31.

Description

  The present invention relates to a developing device used for a copying machine, a facsimile, a printer, and the like, and an image forming apparatus and a process cartridge using the developing device.

  Conventionally, as a developing device used in an image forming apparatus such as a copying machine, a facsimile, or a printer, those described in Patent Document 1 and Patent Document 2 are known. These developing devices convey toner carried on a toner carrying member such as a developing roller that moves on the surface to a developing region that is a region facing the latent image carrying member as the surface moves. In the developing area, the toner on the toner carrier is electrostatically moved by the potential difference between the surface of the toner carrier and the electrostatic latent image on the latent image carrier for development. In such a configuration, the above-described potential difference must be relatively large. This is because the toner must be given a force sufficient to overcome the adhesion force with the developer carrier due to van der Waals force or mirror image force. In addition, a so-called background stain that causes toner particles to adhere to the background portion of the toner carrier may occur. This background stain is generated when the reversely charged toner particles that are charged in the opposite polarity to the normal charged polarity contained in the toner adhere to the background portion of the latent image carrier.

  On the other hand, as described in Patent Document 3, the developing device does not use the toner adsorbed on the surface of the toner carrier or the magnetic carrier for development, but develops toner hopped on the outer peripheral surface of the toner carrier. The one using the flare development method used in the process is known. Specifically, it has a cylindrical toner carrier having a plurality of electrodes arranged at a predetermined pitch in the circumferential direction. These electrodes are formed by repeatedly arranging electrode pairs composed of two adjacent electrodes. An alternating electric field is formed between the two electrodes in each electrode pair. As a result, the toner located on one electrode in the electrode pair floats and landes on the other electrode, or floats on the other electrode and landes on the one electrode. The hopping behavior is shown.

  While repeating such hopping, the toner on the toner carrier is transported to the development region by the surface movement accompanying the rotational driving of the toner carrier. In the developing region, the toner that has floated to the vicinity of the latent image on the latent image carrier is attracted to the electric field by the latent image and does not descend toward the electrode of the toner carrier, and adheres to the latent image. In such a configuration, toner that does not exert an attractive force by hopping is used for development instead of toner that is adsorbed on the surface of the toner carrier or a magnetic carrier. As a result, it is possible to realize low potential development that could not be realized by the conventional one-component development method or two-component development method. For example, toner can be selectively attached to an electrostatic latent image having a potential difference of only a few tens [V] with respect to surrounding non-image portions.

However, even in the developing device having such a configuration, the reversely charged toner particles hopped on the toner carrier may adhere to the background portion of the latent image carrier and cause background staining.
A developing device described in Patent Document 4 has been proposed as a configuration for preventing background contamination in the developing device configured to hop toner on the toner carrier. This developing device is opposite to the outer peripheral surface of the toner carrier at a position upstream of the development area in the surface movement direction of the toner carrier, and is capable of collecting the reversely charged toner contained in the hopped toner. It is the structure provided with a member. The toner collecting member included in the developing device includes a facing surface that faces the toner carrier, and the facing surface is curved so that the spacing between the toner carrier and the toner carrier is constant. Is set to the same value as the development gap, which is the minimum distance between the toner carrier and the latent image carrier in the development region.

At the time of development, a bias is applied so that the potential of the toner recovery member has the same polarity and the same value as the potential of the background portion of the latent image carrier (uniform charging potential). As a result, the potential relationship between the toner recovery member and the toner carrier can be made to be the same as the potential relationship between the background portion and the toner carrier in the development region, and the toner hopping on the surface of the toner carrier can be performed. In addition, the reversely charged toner that may adhere to the background portion of the latent image carrier in the developing region can be selectively attached to the toner collecting member. Since the reversely charged toner causing the background stain can be collected in advance upstream of the development area, the occurrence of the background stain due to the reversely charged toner adhering to the background portion can be prevented.
Japanese Patent Application Laid-Open No. 2005-228561 describes that when the developing operation is completed, the bias applied to the toner collecting member is switched to the discharge bias so that the reversely charged toner attached to the toner collecting member moves to the toner carrier. Thus, the reversely charged toner collected by the toner collecting member at the time of development is returned to the toner carrying member, and then collected by the toner carrying member cleaning member.

As in Patent Document 3 and Patent Document 4, in a developing device configured to hop toner on a toner carrier, a weakly charged toner that is a poorly charged toner different from a reversely charged toner may cause background contamination. It was. The weakly charged toner is a toner particle having a smaller charge amount than the toner particles of the other regular charged toner occupying the majority, and the reason why the weakly charged toner causes the background stain is considered to be as follows. .
That is, the toner particles of the weakly charged toner are different from the toner particles of the normally charged toner in the behavior when hopped due to the difference in chargeability. Specifically, since the toner particles of the weakly charged toner are not easily affected by the electric field, the moving speed is slow, and the normally charged toner that rises later easily collides during the rise during hopping. By being repeated, it is pushed out of the toner cloud. If the force pushed out at this time overcomes the electrostatic repulsive force with the background portion, the weakly charged toner adheres to the background portion and causes soiling.

  As in the developing device described in Patent Document 4, in the configuration in which the potential relationship between the toner recovery member and the toner carrier is the same as the potential relationship between the background portion and the toner carrier in the development region, the toner adheres to the background portion. Any toner other than the reversely charged toner will adhere to the toner collecting member as long as it can cause scumming. For this reason, weakly charged toner that may cause scumming also adheres to the facing surface of the toner recovery member. On the opposite surface of the toner collecting member to which the reversely charged toner and the weakly charged toner are attached, toners having different charging polarities are mixedly attached. It is difficult to set the discharge bias so that all of the poorly charged toner adhering to the opposing surface of the toner collecting member in such a state is moved to the toner carrier. In particular, the weakly charged toner is not easily affected by the electric field, and if it adheres to the toner collecting member, it is difficult to move it to the toner carrying member by the electric field formed between the toner collecting member and the toner carrying member. The toner tends to remain on the toner collecting member. If a part of the poorly charged toner is repeatedly left on the toner collecting member, the opposing surface of the toner collecting member is covered with the remaining toner over time, and the collecting performance of the poorly charged toner is lowered. Dirt gets worse.

  The present invention has been made in view of the above problems, and an object of the present invention is to stably prevent scumming due to poorly charged toner over time in a flare developing type developing device. A developing device, and an image forming apparatus and a process cartridge including the developing device are provided.

  In order to achieve the above object, the invention according to claim 1 is provided with at least two kinds of electrode members whose outer peripheral surface faces the latent image carrier and to which different voltages are applied, and the outer peripheral surface moves endlessly. A toner carrier that transports toner carried on the outer peripheral surface to a developing region that is opposite to the latent image carrier; and a toner supply unit that supplies toner to the outer peripheral surface of the toner carrier, and includes at least two By applying different voltages to different types of electrode members to form a hopping electric field for hopping the toner on the outer peripheral surface of the toner carrier, the toner supplied from the toner supply means is By carrying the toner carrier on the outer peripheral surface of the carrier and moving the surface of the toner carrier, the toner in the hopped state is conveyed to the developing region to form a latent image on the latent image carrier. The latent image is developed by attaching the toner image, and the developing region is downstream of the supply position where the toner supply means supplies the toner to the toner carrier with respect to the surface movement direction of the toner carrier. In a developing device including a toner recovery member that opposes the outer peripheral surface of the toner carrier at a position upstream of the toner carrier and recovers the reversely charged toner contained in the hopped toner, the surface of the toner recovery member moves endlessly An endless moving body that adheres to the surface of the toner collecting member at a toner collecting position facing the toner carrier, and includes the reversely charged toner conveyed by the endless movement of the toner collecting member. A recovery member cleaning means for mechanically removing the poorly charged toner from the surface of the toner recovery member is provided.

  In the present invention, since the poorly charged toner including the reversely charged toner adhering to the surface of the endlessly moving toner recovery member is mechanically removed by the recovery member cleaning means, the toner recovery member is independent of the chargeability of the poorly charged toner. Can be removed. As a result, it is possible to prevent a part of the poorly charged toner from remaining on the toner collecting member, maintain the performance of collecting the poorly charged toner from the toner carrying member, and stably prevent scumming over time. be able to.

  According to the present invention, the flare development type developing device has an excellent effect of being able to stably prevent scumming due to poorly charged toner even over time.

Explanatory drawing of the process unit with which the printer which concerns on embodiment is provided. FIG. 2 is a schematic configuration diagram illustrating a printer. FIG. 2 is a schematic configuration diagram showing the printer while a process unit is being attached and detached. FIG. 3 is a perspective view showing a toner carrying roller of a process unit. FIG. 3 is a schematic plan view showing an electrode configuration of a toner carrying roller. FIG. 3 is an enlarged cross-sectional view showing a toner carrying roller. FIG. 4 is a waveform diagram showing characteristics of a pulse voltage applied to an electrode of a toner carrying roller. FIG. 9 is a schematic diagram illustrating a modified example of a toner carrying roller.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of an electrophotographic printer (hereinafter referred to as a printer 100) will be described.
FIG. 2 is a schematic configuration diagram illustrating the printer 100 according to the present embodiment. The printer 100 can form a full-color image by superimposing black, magenta, cyan, and yellow (hereinafter also referred to as K, M, C, and Y) toner images. The belt unit 1, the four process units 60 (K, M, C, and Y), the four optical writing units 4 (K, M, C, and Y), the registration roller pair 53, the transfer roller 12, and the fixing device 3. A paper feed cassette 50, a paper feed path 52, and the like.

  The belt unit 1 includes a photoconductor belt 11 in which an organic photoconductor serving as a latent image carrier is configured in an endless belt shape, and the photoconductor belt 11 is stretched in a vertically long posture that takes a space in a vertical direction rather than a horizontal direction. However, it moves endlessly in the counterclockwise direction (arrow A direction) in the figure. More specifically, the photosensitive belt 11 is stretched while being supported from the back side by a driving roller 11b, a tension roller 11c, a transfer backup roller 11a, and four developing counter rollers 10 (K, M, C, Y). . Then, the photosensitive belt 11 is moved endlessly by the rotation of a driving roller 11b that is driven to rotate counterclockwise in the drawing by a rotation driving mechanism (not shown). The left extending surface (hereinafter referred to as the left extending surface) in the drawing of the photosensitive belt 11 is in a posture extending substantially in the vertical direction.

  Process units 60 (K, M, C, Y) for K, M, C, Y are arranged in the vertical direction on the left side of the left-hand stretched surface of the photoreceptor belt 11 in the drawing. , Respectively, facing the left-hand stretched surface of the photoreceptor belt 11. These four process units 60 (K, M, C, Y) respectively include a developing device 6 (K, M, C, Y) and a charging device 2 (K, M, Y) for uniformly charging the photosensitive belt 11. C, Y) are held as a single unit on a common holder (not shown) to constitute a process unit 60 in which the developing device 6 and the charging device 2 are integrated. As shown in FIG. 3, the process unit 60 can be attached to and detached from the housing of the printer 100 from the space opened when the belt unit 1 is retracted, and the process unit 60 can be replaced by the user. It has become.

  In FIG. 2 described above, among the four developing devices 6 (K, M, C, and Y), the black charging device 2K is exposed above the black developing device 6K positioned on the uppermost side in the vertical direction. The body belt 11 is disposed so as to face the left-side stretched surface. Further, in the vertical direction, a magenta charging device 2M is disposed between the black developing device 6K and the magenta developing device 6M so as to face the left-side stretched surface of the photosensitive belt 11. A cyan charging device 2C is disposed between the magenta developing device 6M and the cyan developing device 6C so as to face the left-side stretched surface of the photosensitive belt 11. Further, a yellow charging device 2Y is disposed between the cyan developing device 6C and the yellow developing device 6Y so as to face the left-side stretched surface of the photosensitive belt 11.

  On the left side of the four developing devices 6 (K, M, C, Y) arranged in the vertical direction, four optical writing units 4 (K, M, C, Y) are arranged in the vertical direction. It is installed. These optical writing units 4 (K, M, C, Y) are latent images corresponding to colors K, M, C, Y based on image information sent from an external personal computer or scanner (not shown). Is written on the photosensitive belt 11. Based on the image information, the optical writing unit 4 (K, M, C, Y) drives four semiconductor lasers (not shown) to write light Lk, Lm, Lc for K, M, C, Y. , Ly are emitted. Then, while deflecting them by a polygon mirror (not shown), they are reflected by a reflection mirror (not shown) or passed through an optical lens to perform optical scanning on the photosensitive belt 11. Instead of such a configuration, an LED array that performs optical scanning may be used.

  The optical scanning is performed in the dark. Further, the writing lights Lk, Lm, Lc, and Ly corresponding to each color pass between the charging device 2 (K, M, C, Y) and the developing device 6 (K, M, C, Y) of each color. Then, the photosensitive belt 11 is irradiated.

  The photosensitive belt 11 extends from the upper side to the lower side in the vertical direction between the lowermost driving roller 11b and the uppermost tension roller 11c among the plurality of stretching rollers that stretch the photosensitive belt 11 itself. Move almost straight toward you. In this process, first, when passing through a position facing the black charging device 2K, for example, the negative charge is uniformly charged. Then, the area corresponding to the K image portion is neutralized on the surface of the photosensitive belt 11 charged to the negative polarity by the optical scanning by irradiating the black writing light Lk corresponding to the black image information. An electrostatic latent image is formed. The surface of the photosensitive belt 11 carries a black electrostatic latent image, and then passes through a position facing the black developing device 6K. At this time, the black developing device 6K develops the black toner latent image formed on the photosensitive belt 11 by attaching K toner particles to the image portion of the black electrostatic latent image, and the black electrostatic latent image is used as the K toner image. Visualize.

  The photosensitive belt 11 on which the K toner image is formed is again uniformly charged by the magenta charging device 2M as it moves from the upper side to the lower side in the vertical direction. At this time, even when a toner image has already been formed on the photosensitive belt 11, the surface of the photosensitive belt 11 including the toner image is uniformly charged. The photosensitive belt 11 is uniformly charged by the magenta charging device 2M, and then carries a magenta electrostatic latent image by optical scanning with the magenta writing light Lm. The magenta electrostatic latent image is developed by the magenta developing device 6M to become an M toner image.

  The photosensitive belt 11 on which the M toner image is formed is uniformly charged again by the cyan charging device 2C as it moves from the upper side to the lower side in the vertical direction. At this time, even when a toner image has already been formed on the photosensitive belt 11, the surface of the photosensitive belt 11 including the toner image is uniformly charged. The photosensitive belt 11 is uniformly charged by the cyan charging device 2C, and then carries a cyan electrostatic latent image by optical scanning with cyan writing light Lc. This cyan electrostatic latent image is developed by the cyan developing device 6C to become a C toner image. At this time, the entire area or a partial area of the C toner image is developed in a state of being superimposed on the M toner image already formed on the photosensitive belt 11, and the overlapping position is determined by M and C. Secondary color part.

  The photosensitive belt 11 on which the C toner image is formed is uniformly charged again by the yellow charging device 2Y as it moves from the upper side to the lower side in the vertical direction. At this time, even when a toner image has already been formed on the photosensitive belt 11, the surface of the photosensitive belt 11 including the toner image is uniformly charged. The photosensitive belt 11 is uniformly charged by the yellow charging device 2Y, and then carries a yellow electrostatic latent image by optical scanning with the yellow writing light Ly. The yellow electrostatic latent image is developed by the yellow developing device 6Y to become a Y toner image. At this time, the entire area or a partial area of the Y toner image is developed in a state of being superimposed on the M toner image, the C toner image, or the secondary color portion of the MC already formed on the photosensitive belt 11. Is done. As a result, the overlapping portion of the Y toner image becomes a secondary color portion by M and Y, a secondary color portion by C and Y, or a tertiary color portion by M, C and Y.

  By superimposing and developing the K, M, C, and Y toner images as described above, a four-color superimposed toner image is formed on the front surface (loop outer surface) of the photosensitive belt 11. As the charging devices 2 (K, M, C, Y) for K, M, C, and Y, those that uniformly charge the photosensitive belt 11 by corona discharge are used. According to the charging device 2 (K, M, C, Y) having such a configuration, the photosensitive belt 11 can be uniformly charged in a non-contact manner, and therefore, development on the upstream side of the charging position is possible. The apparatus 6 can perform charging while avoiding the disturbance of the toner image due to the contact between the toner image already formed on the photosensitive belt 11 and the charging member.

  The photosensitive belt 11 that has passed through the yellow developing region, which is the position facing the yellow developing device 6Y, moves relative to the vertical direction from the lower side to the upper side when the photosensitive belt 11 passes around the driving roller 11b. Will come to do. Then, it enters the place where the transfer backup roller 11a is wound. The transfer roller 12 is brought into contact with the part of the hung portion from the front surface side to form a transfer nip. While the transfer backup roller 11a is grounded, a transfer bias is applied to the conductive transfer roller 12 by a bias applying means (not shown). As a result, the toner image on the photosensitive belt 11 is electrostatically moved from the transfer backup roller 11a side to the transfer roller 12 side between the transfer backup roller 11a and the transfer roller 12 with the transfer nip interposed therebetween. An electric field is formed.

The paper feeding cassette 50 constitutes a paper feeding device that stores a transfer material such as recording paper P and starts conveying the transfer material during image formation.
At the time of image formation, the paper feed cassette 50 rotates the paper feed roller 51 at a predetermined timing, thereby feeding the recording paper P stored in the cassette toward the paper feed path 52. The fed recording paper P is sandwiched between rollers of a registration roller pair 53 disposed below the transfer nip in the drawing. As soon as the registration roller pair 53 sandwiches the leading end of the recording paper P, the rotation of the registration roller 53 is temporarily stopped. Then, rotation driving is resumed at a timing at which the recording paper P can be synchronized with the four-color superimposed toner image on the photosensitive belt 11, and the recording paper P is sent to the transfer nip.

  At the transfer nip, the four-color superimposed toner image formed on the photosensitive belt 11 is in close contact with the recording paper P, and the toner image is transferred from the photosensitive belt 11 to the recording paper P by the action of the nip pressure and the transfer electric field. Thus, a full-color toner image is formed in combination with the white color of the recording paper P.

The fixing device 3 is a device that fixes an unfixed toner image formed on a transfer material such as recording paper P.
The recording sheet P on which the toner image is formed on the surface after passing through the transfer nip is sent to the fixing device 3 from the transfer nip. The fixing device 3 forms a fixing nip by abutting a fixing roller 3b including a heat source such as a halogen lamp and a pressure roller 3a disposed so as to be in pressure contact with the fixing roller 3b. The paper P is sandwiched in the fixing nip. Then, the toner image is fixed on the recording paper P by the action of heating and nip pressure by the fixing roller 3b, and a visible image is formed on the recording paper P.

  The recording paper P on which a toner image is fixed in the fixing device 3 and a visible image is formed on the surface is discharged outside the apparatus after passing through a pair of paper discharge rollers (not shown).

  In the printer 100, no cleaning means is provided for cleaning the transfer residual toner adhering to the surface of the photosensitive belt 11 after passing through the transfer nip. The photoreceptor belt 11 enters the development area for the next process K, M, C, and Y with the transfer residual toner attached, but the four charging devices 2 (K, M, and C). , Y), the transfer residual toner is charged to the normal polarity (negative polarity in the present embodiment), so that it is transferred to the recording paper P when it enters the transfer nip again and is removed from the photosensitive belt 11. When the transfer residual toner is transferred to the recording paper P, some image distortion occurs. However, even if the transfer residual toner is transferred to the recording paper P, if the amount is small, the image quality is not deteriorated enough to be visually recognized. .

  When the amount of the transfer residual toner is relatively large, the transfer residual toner is removed from the surface of the photosensitive belt 11 after passing through the transfer nip and before entering the position facing the black charging device 2K. A cleaning means may be provided. In this case, the cleaning unit and the developing device can be integrally configured as a process unit.

  FIG. 1 is an explanatory diagram of one process unit 60 among the four process units 60 (K, M, C, Y). Each process unit 60, which is a toner image forming means for forming a toner image of each color on the photoreceptor belt 11 as an image carrier, is different in color of toner D to be used, but the other configurations are almost the same. It is. Therefore, in the following description, K, M, C, and Y color coding symbols are omitted. The developing device 6 in this embodiment is an example of a developing device using a one-component developer made of nonmagnetic toner.

  As shown in FIG. 1, a charging device 2 for uniformly charging the surface of the photosensitive belt 11 is disposed upstream of the developing device 6 in the surface movement direction of the photosensitive belt 11. In the present embodiment, corona charging is employed as the charging device 2. If a non-contact charging means such as corona charging is used, the upstream developing device 6 has already placed on the photosensitive belt 11 as described above. The photosensitive belt 11 can be charged without disturbing the toner image formed on the toner image.

  As shown in FIG. 1, the developing device 6 includes a casing 61 that forms a toner accommodating portion 66 that accommodates toner to be supplied to the photosensitive belt 11, and a roller shape that faces the photosensitive belt 11 through an opening 90 of the casing 61. And a toner carrying roller 7 which is a toner carrying member. Further, the developing device 6 supplies toner to the supply roller 62 while stirring the toner D in the toner container 66 and the supply roller 62 that is a toner supply unit that supplies the toner D in the toner container 66 to the toner carrying roller 7. And a paddle 64 that is a toner stirring means for pumping up the toner. The toner carrying roller 7, the supply roller 62, and the paddle 64 are rotated by a rotation driving mechanism (not shown).

  The toner D is accommodated in the toner accommodating portion 66 of the developing device 6, and the toner D transferred from the toner accommodating portion 66 to the supply roller 62 is frictionally charged with the supply roller 62, The frictionally charged toner D is supplied from the supply roller 62 onto the toner carrying roller 7. A supply bias is applied to the supply roller 62 from a supply power source 62a. In the developing device 6 shown in FIG. 1, a DC voltage is applied as the supply bias. However, the supply bias may be a DC voltage or an AC voltage, or a bias obtained by superimposing the AC voltage on the DC voltage. The supply bias generates a supply electric field between the supply roller 62 and the toner carrying roller 7. The toner carried on the supply roller 62 receives an electrostatic force from the supply electric field, moves away from the supply roller 62, and moves to the surface of the toner carrying roller 7.

  The toner carrying roller 7 includes a toner carrying electrode body 20 composed of a plurality of electrodes, which will be described in detail later, on the surface thereof, and carries the toner in a cloud state by hopping the toner by an electric field formed between the electrodes. Then, the toner in the cloud state is transported to the developing area which is a portion facing the photosensitive belt 11 by the surface movement by the rotational drive. A blade-shaped regulating member 63 that regulates the amount of toner on the toner carrying roller 7 is installed upstream of the toner carrying roller 7 in the toner conveyance direction with respect to the development area. The regulating member 63 is in contact with the toner carrying roller 7, and when passing through the contact portion between the regulating member 63 and the toner carrying roller 7, the toner is caused by friction between the toner carrying roller 7 and the regulating member 63 and the toner. Charged. The regulating member 63 is not limited to a blade-like member, and a roller-like member may be brought into contact with the toner carrying roller 7.

  As the toner D accommodated in the developing device 6 of the present embodiment, the following is used. Binder resin can be radically polymerized with styrene or acrylic polymerizable monomer dispersed in water together with polymerization initiator, or polymerized by polyaddition reaction with polyester resin dispersed in water. Let These are non-magnetic toner particles having a weight average particle diameter of about 5 [μm] obtained by adding a colorant, a charge control agent and the like to granulation.

Next, the toner carrying roller 7 will be described.
The toner carrying roller 7 is a roller-like toner carrying body having a plurality of electrodes therein in order to generate an electric field for conveying, developing, and collecting powder toner particles. At the time of image formation, the toner carrying roller 7 is opposed to the photosensitive belt 11 which is a latent image carrying member in a non-contact manner with a gap of 50 to 1000 [μm], preferably 150 to 400 [μm]. .

FIG. 4 is a perspective view showing the toner carrying roller 7, and FIG. 5 is a schematic plan view showing the electrode configuration of the toner carrying roller 7. FIG. 6 is an enlarged cross-sectional view schematically showing a partial cross section near the surface of the toner carrying roller 7.
As shown in FIG. 4, the toner carrying roller 7 has a plurality of electrodes arranged on the roller-shaped peripheral surface at a predetermined pitch in the roller circumferential direction while extending in the roller axial direction. More specifically, as shown in FIG. 5, the toner carrying electrode body 20 composed of a plurality of electrodes is formed by alternately arranging A-phase electrodes 20a and B-phase electrodes 20b in the circumferential direction of the roller. The A-phase electrode 20a and the B-phase electrode 20b form a comb-like electrode configuration.

  As shown in FIG. 4, an A-phase common electrode 21a is provided at one end in the axial direction of the roller portion of the toner carrying roller 7 so as to extend over the entire circumference of the roller portion. One end portions of the plurality of A-phase electrodes 20a are connected to each other. Further, a B-phase common electrode 21b is provided at the other end of the roller portion in the axial direction so as to extend over the entire circumference of the roller portion, and this includes the other ends of the plurality of B-phase electrodes 20b. Each part is connected.

  For convenience, although not shown in FIGS. 4 and 5, a surface layer 22 made of a non-conductive material is coated on the plurality of A-phase electrodes 20a and B-phase electrodes 20b as shown in FIG. The surface layer 22 prevents the contact between the plurality of electrodes and the toner. However, the surface layer 22 is not provided on the A-phase common electrode 21a and the B-phase common electrode 21b shown in FIGS. 4 and 5, and the two common electrodes are exposed.

  The A-phase brush contact member 26 a fixed to the casing 61 rubs against the A-phase common electrode 21 a that moves endlessly on the rotation track as the toner carrying roller 7 rotates. Then, the A-phase pulse voltage output from the power supply 24 shown in FIGS. 4 and 6 is applied to each A-phase electrode 20a via the A-phase brush contact member 26a and the A-phase common electrode 21a. Further, the B-phase brush contact member 26b fixed to the casing rubs against the B-phase common electrode 21b that moves endlessly on the rotation track as the toner carrying roller 7 rotates. Then, the B-phase pulse voltage output from the power supply 24 is applied to each B-phase electrode 20b via the B-phase brush contact member 26b and the B-phase common electrode 21b.

  Hereinafter, a set of a plurality of A-phase electrodes 20a to which the A-phase pulse voltage is applied is referred to as an A-phase electrode group. A set of a plurality of B phase electrodes 20b to which a B phase pulse voltage is applied is referred to as a B phase electrode group. Since the A-phase electrodes 20a and the B-phase electrodes 20b are alternately arranged, the arrangement order of the plurality of A-phase electrodes 20a from the predetermined position in the roller circumferential direction is odd or even. Further, the arrangement order of the plurality of B-phase electrodes 20b is an even number when the arrangement order of the A-phase electrodes 20a is an odd number, and an odd number when the arrangement order of the A-phase electrodes 20a is an even number. .

For example, a rectangular wave-shaped A-phase pulse voltage Va that repeats rising and falling at a predetermined cycle as shown in FIG. 7 is applied to the A-phase electrode group. On the other hand, the B-phase electrode group is applied with a rectangular wave-shaped B-phase pulse voltage Vb whose rising and falling phases are opposite to the A-phase pulse voltage Va as shown in FIG. The period T, frequency f (f = 1 / T), peak-to-peak voltage Vpp, and amplitude center potential Vc of each pulse voltage are the same. When such a pulse voltage is applied, the toner on the toner carrying roller 7 floats from directly above the A-phase electrode 20a and lands on the adjacent B-phase electrode 20b so as to draw a parabola. The reciprocating movement by hopping is repeated such that it floats right above the B-phase electrode 20b and returns to the adjacent A-phase electrode 20a so as to draw a parabola.
As described above, the power supply 24 is a voltage supply unit that supplies a voltage so that the electric field between the plurality of electrodes (the A-phase electrode 20a and the B-phase electrode 20b) changes with time.

  As described above, the toner that has been repeatedly reciprocated by hopping in this way is conveyed to the development area by the rotational driving of the toner carrying roller 7. In the developing area, toner that reaches the vicinity of the electrostatic latent image on the photosensitive belt 11 near the apex of the parabolic hopping locus deviates from the hopping locus while being pulled by the electrostatic force of the electrostatic latent image. And adhere to the electrostatic latent image. On the other hand, the toner that reaches the vicinity of the background portion (uniformly charged portion) of the photosensitive belt 11 near the apex of the parabolic hopping locus descends without departing from the hopping locus, and the surface of the toner carrying roller 7. Land on.

  In such a configuration, by using toner in a state in which the adsorbing force with the toner carrying roller 7 is released by hopping, a low potential that cannot be realized by the conventional one-component development method or the two-component development method. Development can be realized. Hereinafter, as in the printer 100 of the present embodiment, a method of performing development by transferring toner to the development region by moving the surface of the toner carrier while reciprocating the toner between the electrodes of the toner carrier by hopping (Flare). ) Development method.

As the A-phase pulse voltage Va and the B-phase pulse voltage Vb, the peak-to-peak voltage Vpp is 200 to 1000 [V], the frequency f is 0.5 to 5 [kHz], and the amplitude central potential Vc. Is between the latent image potential on the photosensitive belt 11 and the background potential. The amplitude center potential Vc is changed between the latent image potential and the background portion potential depending on the development conditions.
As shown in FIG. 7, the phases of the A-phase pulse voltage Va and the B-phase pulse voltage Vb are shifted from each other by ½ period (π). Thereby, during application of the pulse voltage, a potential difference having a value equal to Vpp is always generated between the A-phase electrode 20a and the B-phase electrode 20b. This potential difference generates an electric field between different types of electrodes, and the toner hops between the electrodes in accordance with the electric field.

  As a combination of two pulse voltages applied to the A-phase electrode group and the B-phase electrode group, in the case of the rectangular wave shown in FIG. 7, voltage switching occurs instantaneously, which is suitable for toner hopping. It is not limited to. In addition to the combinations shown in FIG. 7, a combination of an A-phase pulse voltage Va made up of a rectangular wave and a B-phase pulse voltage Vb of a DC voltage made up of an amplitude center potential Vc that is the center value of the amplitude of the rectangular wave may be adopted. Good. Further, the relationship between the A phase and the B phase in this combination may be reversed. Further, as the waveform of the pulse voltage, other than a rectangular wave, for example, a sine wave, a triangular wave having a time constant, a sine wave corresponding to the time constant, or the like may be employed.

  As shown in FIG. 6, on the surface of the support substrate 23 of the toner carrying roller 7, two types of electrodes (20a, 20b) are alternately arranged at predetermined intervals along the toner conveyance direction. And on these electrodes and on the non-electrode forming surface of the support substrate 23 is an insulating transport surface forming member that forms a transport surface, and serves as a protective film that covers the surfaces of the electrodes (20a, 20b). A surface layer 22 formed of an inorganic or organic insulating material is laminated.

Examples of the support substrate 23 include base materials made of an insulating material such as a glass base material, a resin base material, and a ceramic base material. Further, a substrate made of a conductive material such as stainless steel (SUS) and an insulating film such as SiO ₂ formed thereon, a base material made of a material that can be deformed flexibly such as a polyimide film, or the like may be used.

  The A-phase electrode 20a and the B-phase electrode 20b are formed as follows, for example. That is, a film made of a conductive material such as Al or Ni—Cr is formed on the surface of the support substrate 23 with a thickness of 0.1 to 10 [μm], preferably 0.5 to 2.0 [μm]. Then, this film is formed by patterning into a predetermined electrode shape by a photolithography method or the like. And after forming each electrode, the surface layer 22 is formed on it. The width (length in the short direction) of each electrode (20a, 20b) is desirably 1 to 20 times the average particle diameter of the toner particles.

As the surface layer 22, for example, a material such as SiO ₂ , TiO ₂ , TiO ₄ , SiON, BN, TiN, Ta ₂ O ₅ is used with a thickness of 0.5 to 10 [μm], preferably 0.5 to 3 [ [mu] m] can be exemplified.

  As shown in FIG. 5, the A-phase common electrode 21a and the B-phase common electrode 21b can be formed by the same method as the A-phase electrode 20a and the B-phase electrode 20b. In addition to the A-phase electrode 20a and the B-phase electrode 20b, it can be formed as follows. That is, as shown in FIG. 8, the flange member 25 made of metal is press-fitted from the end in the axial direction into the roller portion on which the A-phase electrode and the B-phase electrode of the toner carrying roller 7 are formed. 25 is connected to the end of the A-phase electrode or B-phase electrode on the roller section. The metal surface of the flange member 25 is used as a common electrode. As the flange member 25, it is desirable to use a member integrally formed with the rotating shaft member of the toner carrying roller 7 as shown in the figure.

  By the way, in the conventional two-component development method, development is performed while rubbing the toner adhering to the surface of the magnetic carrier magnetically attracted to the developer carrying member together with the magnetic carrier onto the latent image carrying member. Further, in the conventional one-component development system, the toner carried on the surface of the developer carrying member is rubbed against the latent image carrying member, or the toner on the developer carrying member arranged in non-contact with the latent image carrying member. The image is reciprocated between the developer carrying member and the latent image carrying member by an alternating electric field. In these methods, when overlay development is performed as in the printer 100 of the present embodiment, the toner in the toner image previously developed on the latent image carrier is developed in the subsequent color during the subsequent development. Transfers into the device and causes color mixing.

  On the other hand, in the printer 100 of this embodiment, development is performed without causing the toner on the toner carrying roller 7 to rub against the photosensitive belt 11. Further, the toner does not reciprocate between the surface of the photoreceptor belt 11 and the surface of the toner carrying roller 7 by an alternating electric field, and the hopped toner that does not contribute to development is brought into contact with the photoreceptor belt 11. Return to the toner carrying roller 7 without any change. In addition, the toner that has contributed to the electrostatic latent image on the photosensitive belt 11 is not transferred again onto the toner carrying roller 7. As a result, it is possible to avoid color mixing in the developing device for subsequent colors.

Next, the characteristic part of the developing device 6 will be described.
As shown in FIG. 1, the developing device 6 of the present embodiment is located at a position downstream of the restriction position by the restriction member 63 and upstream of the development region with respect to the surface movement direction of the toner carrying roller 7. A toner collection roller 31 that is a toner collection member is provided so as to face the surface of the toner carrying roller 7. Further, the developing device 6 includes a recovery roller cleaning blade 32 that is a recovery member cleaning unit that removes toner from the toner recovery roller 31. The restriction position is downstream of the supply position where the supply roller 62 supplies toner to the toner carrying roller 7. Further, a recovery roller bias power source 68 for applying a predetermined recovery bias to the toner recovery roller 31 is provided.

The toner collection roller 31 is opposed to the outer peripheral surface of the toner carrying roller 7 and collects the poorly charged toner contained in the toner in a state where it is hopped to form a cloud. Further, the toner collection roller 31 is an endless moving body whose surface moves endlessly by being rotationally driven in a direction indicated by an arrow in FIG. 1 (clockwise direction) by a driving source (not shown).
The collection roller cleaning blade 32 contacts the toner collection roller 31 at a position different from the toner collection position where the toner collection roller 31 faces the toner carrying roller 7. The toner is mechanically removed by adhering to the surface of the toner collecting roller 31 at the toner collecting position and scraping off the toner conveyed by the endless movement of the toner collecting roller 31 from the surface of the toner collecting roller 31.
The toner removed by the collection roller cleaning blade 32 is stored in the recovery toner storage unit 33 and is discharged toward a waste toner bottle provided outside the developing device 6 by a discharge mechanism (not shown).

Here, background contamination in the developing device configured to hop toner on the toner carrier will be described.
In a developing device configured to hop toner on a toner carrier, such as the developing device described in Patent Documents 3 and 4 and the developing device 6 of this embodiment, the reversely charged toner particles hopped on the toner carrier are latent. It may adhere to the background of the image carrier and cause background stains. Further, unlike the image forming apparatuses described in Patent Document 1 and Patent Document 2, the toner particles of the high charge amount toner contained in the toner may cause background staining. The high charge amount toner particles that are charged to the normal polarity side of the average value more than the average value are attached to the background portion by overcoming the repulsive force with the background portion of the latent image carrier when pressed from the toner cloud. is there.

In the developing device described in Patent Document 4, toner particles of a reversely charged toner or a high charge amount toner are collected before development to reduce background contamination. However, the agglomerated weakly charged toner particles contained in the toner may cause scumming.
Deteriorated toner whose charging characteristics have been lowered due to friction during driving of the developing device, such as new toner, is mixed with toner that has not deteriorated charging characteristics, so that it will float on the undegraded toner. Are pushed out, and deteriorated toners gather to form an aggregate. Such an aggregate of deteriorated toner does not increase the amount of charge when frictionally charged due to friction caused by agitation or friction when passing through the regulating member, and becomes aggregated weakly charged toner particles.

The agglomerated weakly charged toner particles have a large particle size and a small restraint force due to the electric field, so the moving speed by the alternating electric field is slow, and the moving speed of the normally charged toner cannot be kept up. For this reason, in the state where the aggregated weakly charged toner is lifted, the regular charged toner that is lifted later collides, and thus the aggregated weakly charged toner is pushed from below and pushed out above the clad of the regular charged toner. .
In this way, the agglomerated weakly charged toner pushed out above the cloud has a repulsive force caused by the collision of countless regular charged toner particles in the cloud when it reaches the vicinity of the latent image carrier. In response, it is pushed toward the latent image carrier. If this pressing force is stronger than the repulsive force (relatively weak repulsive force because it is weakly charged) with the background portion of the latent image carrier, the aggregated weakly charged toner particles adhere to the background portion and agglomerated weakly charged The background is contaminated with toner particles.

  Further, here, the scumming due to the aggregated weakly charged toner particles has been described. However, even a weakly charged toner having the same particle size as that of the regular charged toner causes the scumming. That is, the toner particles of the weakly charged toner have a smaller moving speed than the agglomerated particles, but the moving speed by the alternating electric field is slow because the charge amount is small, and the toner particles of the normally charged toner can collide. Therefore, it can cause soiling as well as the aggregated matter.

The toner D in the toner container 66 of the developing device 6 is agitated by the paddle 64, pumped up to the supply roller 62, and then supplied to the toner carrying roller 7. The toner that is carried on the toner carrying roller 7 and does not contribute to the development when passing through the developing area reaches the opposite portion to the supply roller 62 by the surface movement of the toner carrying roller 7 and is collected by the supply roller 62. The toner is returned to the toner container 66. During such circulation, a plurality of members and the toner are rubbed with each other, so that a load is applied to the toner and deterioration occurs. The deteriorated toner has lower charging characteristics.
Further, when the toner in the toner container 66 decreases, new toner is supplied from the toner supply port 67. Since the new toner is excellent in charging characteristics, when the deteriorated toner and the new toner having different charging characteristics are mixed in the toner container 66, the deteriorated toner floats on the new toner. The deteriorated toner gathers on the new toner and aggregates to form an aggregate of the deteriorated toner.

The agglomerated toner is a collection of deteriorated toners having low chargeability. Therefore, even if the toner is agitated and regulated by the regulating member, the charge amount does not increase so much and becomes weakly charged toner particles. Further, not only the agglomerated toner but also the deteriorated toner becomes weakly charged toner particles.
On the upstream side of the restriction position on the surface of the toner carrying roller 7, the amount of toner on the toner carrying roller 7 is large, so that the cloud state due to the alternating electric field is not sufficient. For this reason, the action of pushing out the weakly charged toner from the cloud is insufficient, and the weakly charged toner is carried on the toner carrying roller 7 in a mixed state without being separated from other regular charged toners, and passes through the regulation position.

After passing the regulation position, the amount of toner carried on the toner carrying roller 7 becomes a desired amount and the cloud state is also stabilized, so that the action of pushing out the weakly charged toner from the cloud works, and the weakly charged toner is a cloud of regular charged toner. It will be in the state pushed out above.
When the cloud in such a state reaches the development area, the weakly charged toner pushed out above the cloud may adhere to the background portion of the photoreceptor belt 11 and become soiled.
In order to solve such a problem, in the developing device 6 shown in FIG. 1, by providing the toner collection roller 31 between the regulation position and the development area, the charging failure that contributes to the background contamination of the toner after regulation of the toner layer. The toner can be collected before entering the developing area.

Further, the toner collection roller 31 is rotationally driven in a direction indicated by an arrow in FIG. 1 (clockwise direction in FIG. 1) by a driving unit (not shown). By this rotation, the toner collection roller 31 moves so that the surface movement direction at the collection position is opposite to the surface movement direction of the toner carrying roller 7.
When the toner collected on the toner collecting roller 31 at the collecting position reaches the contact position between the toner collecting roller 31 and the collecting roller cleaning blade 32 as the surface of the toner collecting roller 31 moves, the collecting roller cleaning blade 32 It is scraped off from the surface of the toner recovery roller 31 and is stored in the recovery toner storage portion 33.
The developing device 6 is configured to discharge the toner stored in the collected toner storage portion 33 toward the waste toner bottle. However, the developing device 6 does not include a discharge mechanism and stores the toner in the recovered toner storage portion 33 to store the toner in the process unit 60. The toner may be collected together with the developing device 6 at the time of replacement.

  The surface movement direction of the toner collection roller 31 may be a direction in which the toner collection roller 31 is moved in the direction opposite to the surface of the toner carrying roller 7 at the collection position that is opposite to the toner carrying roller 7 as in the present embodiment. desirable. By moving the surface in a direction opposite to the surface of the toner carrying roller 7, the air current on the surface layer of the toner carrying roller 7 is peeled off, so that the weakly charged toner existing in the upper layer of the cloud can be easily separated.

The toner collection roller 31 is not in contact with the toner carrying roller 7. The collection gap that is the distance between the toner collection roller 31 and the toner carrying roller 7 at the collection position is set to be equal to or less than the development gap that is the distance (minimum gap) between the photosensitive belt 11 and the toner carrying roller 7 in the development region. ing.
Further, the toner collecting roller 31 is a conductive member, and the developing device 6 is a collecting roller bias that is a collecting bias applying unit that applies a bias having the same polarity as the normally charged toner of the hopped toner to the toner collecting roller 31. A power supply 68 is provided. The bias applied by the recovery roller bias power source 68 applies a charging failure toner recovery bias having the same polarity and the same value as the background portion (uniform charging potential) of the photosensitive belt 11 to the toner recovery roller 31. .
That is, the surface potential of the toner recovery roller 31 becomes the same polarity and the same value as the background potential on the photosensitive belt 11 by applying the recovery bias of the recovery roller bias power source 68.

  The toner collection roller 31 is not attracted to the normally charged toner that does not adhere to the background portion of the photoreceptor belt 11 in the development region when the collection bias is applied. Thereby, toner particles of poorly charged toner that may adhere to the background portion in the development region can be selectively attached to the toner recovery roller 31 and recovered.

  As the toner collecting roller 31, it is desirable to use a roller made of a conductive material such as metal and coated with an insulating layer made of an insulating material. With such a configuration, direct contact between the toner particles and the conductive surface of the toner recovery roller 31 is prevented, and charge injection into the toner particles caused by the direct contact and the charge of the toner particles to the electrode layer are prevented. Leaks can be avoided. Thus, the poorly charged toner can be stably recovered from the toner carrying roller 7.

  A toner recovery member to which a bias having the same polarity and the same value as the background potential of the photoreceptor is applied at a position facing the toner carrier upstream of the development area is attached to the background area in the development area. It is possible to selectively collect toner particles of poorly charged toner that may be at risk. Then, by applying a bias of reverse polarity to the toner collecting member during non-development, of the poorly charged toner, the reversely charged toner can be returned from the toner collecting member to the toner carrier. A poorly charged toner having the same polarity as the normally charged toner like the weakly charged toner cannot be returned to the toner carrier.

  For example, after the reversely charged toner is returned to the toner carrier, it is applied to the electrode member and the toner recovery member of the toner carrier to form an electric field for returning the poorly charged toner having the same polarity as the normally charged toner to the toner carrier. Although it is conceivable to perform control to switch the bias, the control becomes complicated, and the operation time for collecting the toner from the toner collecting member during non-development becomes longer. Further, even if the above-described electric field is formed by performing such control, it is very difficult to return the weakly charged toner from the toner recovery member to the toner carrier by electrostatic force, which is hardly affected by the electric field. If a part of the poorly charged toner is repeatedly left on the toner collecting member, the opposing surface of the toner collecting member is covered with the remaining toner over time, and the collecting performance of the poorly charged toner is lowered. Dirt gets worse.

  On the other hand, in the developing device 6 according to the present embodiment, the poorly charged toner adhering to the surface of the toner recovery roller 31 is mechanically removed by the recovery roller cleaning blade 32. Can be removed. As a result, it is possible to prevent a part of the poorly charged toner from remaining on the toner collecting roller 31, maintain the performance of collecting the poorly charged toner from the toner carrying roller 7, and stably remove the stain even over time. Can be prevented.

In the developing device 6, by providing a toner collecting roller 31 that collects incompletely charged toner in advance on the upstream side of the developing area with respect to the toner carrying direction of the toner carrying roller 7, the occurrence of background contamination due to the incompletely charged toner in the developing area. Is preventing.
Further, the hopping state of the toner transported to the recovery position where the toner recovery member and the toner carrier face each other is when the non-image portion (background portion) on the latent image carrier faces the toner carrier in the development region. By making the development area the same as the hopping state of the toner being conveyed, only the poorly charged toner that contributes to background contamination is collected.

Specifically, the configuration is as follows.
A toner collecting roller 31 that is a conductive member is provided so as to face the toner carrying roller 7, and the distance between the toner carrying roller 7 and the toner collecting roller 31 is set to be the distance between the toner carrying roller 7 and the photosensitive belt 11 in the developing region. Same as. Further, the collection roller bias power supply 68 applies the collection bias so that the non-image portion potential (background portion potential) on the photoreceptor belt 11 and the surface potential of the toner collection roller 31 become the same potential.
With such a configuration, only the poorly charged toner is collected by being attached to the toner collecting roller 31 before entering the developing region. Further, a recovery roller cleaning blade 32 that is a recovery member cleaning unit is provided, and the toner attached on the toner recovery roller 31 is recovered.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
At least two types of electrode members such as an A-phase electrode 20a and a B-phase electrode 20b, to which the outer peripheral surface faces a latent image carrier such as the photosensitive belt 11 and different voltages are applied, are moved endlessly. As a result, a toner carrying member such as a toner carrying roller 7 that conveys toner carried on the outer peripheral surface to a developing region that is opposite to the latent image carrying member, a supply roller 62 that supplies toner to the outer peripheral surface of the toner carrying member, and the like Toner supply means, and by applying different voltages to at least two types of electrode members to form a hopping electric field on the outer peripheral surface of the toner carrier, The supplied toner is carried on the outer peripheral surface of the toner carrier, and the toner carrier is moved to carry the hopped toner to the development area. The latent image is developed by adhering to the latent image on the latent image carrier, and the toner supply means is downstream of the supply position where the toner supply means supplies the toner to the toner carrier with respect to the surface movement direction of the toner carrier. Development provided with a toner collecting member such as a toner collecting roller 31 that is opposite to the outer peripheral surface of the toner carrier at a position on the side and upstream of the developing area and collects the reversely charged toner contained in the hopped toner In a developing device such as the apparatus 6, the toner collecting member is an endless moving body whose surface moves endlessly, and the toner collecting member adheres to the surface of the toner collecting member at a toner collecting position facing the toner carrying member. A collection roller cleaning blade 32 that mechanically removes poorly charged toner including reversely charged toner conveyed by endless movement from the surface of the toner collection member. Comprising a collecting member cleaning means. According to this, as described in the above embodiment, the poorly charged toner adhering to the surface of the endlessly moving toner recovery member is mechanically removed by the recovery member cleaning unit, and therefore, regardless of the chargeability of the poorly charged toner. The toner can be removed from the toner collecting member. Therefore, it is possible to prevent a part of the poorly charged toner from remaining on the toner collecting member, maintain the performance of collecting the poorly charged toner from the toner carrying member, and stably prevent scumming over time. Can do.
(Aspect B)
In (Aspect A), the toner collecting member such as the toner collecting roller 31 is not in contact with the toner carrying member such as the toner carrying roller 7, and the collecting is the distance between the toner collecting member and the toner carrying member at the toner collecting position. The gap is set to be equal to or smaller than the development gap which is the distance between the latent image carrier such as the photosensitive belt 11 and the toner carrier in the development region. According to this, as described in the above embodiment, the poorly charged toner that may adhere to the latent image carrier and contribute to the background contamination can be reliably attached to the toner collecting member.
(Aspect C)
In the aspect of (Aspect A) or (Aspect B), the toner collection member such as the toner collection roller 31 has a surface movement direction at the toner collection position opposite to the surface movement direction of the toner carrier such as the toner carrying roller 7. Move the surface to be in the direction. According to this, as described in the above embodiment, the weakly charged toner existing in the upper layer of the cloud can be easily separated, and the weakly charged toner can be collected more reliably.
(Aspect D)
In any one of the embodiments (A) to (C), the toner collecting member such as the toner collecting roller 31 is a conductive member, and has a bias having the same polarity as that of the normally charged toner in the hopped toner. A recovery bias applying unit such as a recovery roller bias power supply 68 applied to the toner recovery member is provided. According to this, as described in the above embodiment, the poorly charged toner that may adhere to the latent image carrier and contribute to the background contamination can be reliably attached to the toner collecting member.
(Aspect E)
The latent image is developed by attaching toner to the latent image of the latent image carrier such as the photoreceptor belt 11 and the resulting toner image is finally transferred to a recording material such as recording paper P to form an image. In the image forming apparatus such as the printer 100 that performs the above, the developing device according to any one of (Aspect A) to (Aspect D) is used as means for developing the latent image on the latent image carrier. According to this, as described in the above embodiment, it is possible to stably prevent scumming even with lapse of time and to provide a high-quality image stably.
(Aspect F)
A latent image carrier such as the photosensitive belt 11 that carries the latent image; a developing unit that develops the latent image on the latent image carrier; a charging unit such as the charging device 2 that charges the surface of the latent image carrier; A unit comprising at least one of a latent image carrier, such as a charging device 2 in an image forming apparatus such as a printer 100, a charging unit, and a cleaning unit, and a developing unit, including a cleaning unit that cleans the surface of the latent image carrier. In the process cartridge such as the process unit 60 that is configured to be held on a common holding body and can be integrally attached to and detached from the image forming apparatus main body, any one of (Aspect A) to (Aspect D) is used as the developing unit. One embodiment of the developing device is used. According to this, as described in the above embodiment, a developing device that can stably prevent scumming over time and can create a stable image over time can be used as a developing device that constitutes a process cartridge. Both members can be removed from the apparatus main body, and the exchange of the developing apparatus that can create a stable image can be improved.

DESCRIPTION OF SYMBOLS 1 Belt unit 2 Charging apparatus 3 Fixing apparatus 4 Optical writing unit 6 Developing apparatus 7 Toner carrying roller 10 Developing counter roller 11 Photosensitive belt 12 Transfer roller 20 Toner carrying electrode body 20a A phase electrode 20b B phase electrode 21a A phase common electrode 21b B-phase common electrode 22 Surface layer 23 Support substrate 24 Power supply 31 Toner recovery roller 32 Recovery roller cleaning blade 33 Recovery toner storage unit 50 Paper feed cassette 60 Process unit 62 Supply roller 63 Restriction member 64 Paddle 66 Toner storage unit 67 Toner supply port 68 Recovery roller bias power supply 100 Printer

JP-A-9-197781 JP-A-9-329947 JP-A-3-21967 JP 2008-116599 A

Claims (6)

The outer peripheral surface is opposed to the latent image carrier, and includes at least two kinds of electrode members to which different voltages are applied. The toner carried on the outer peripheral surface by the endless movement of the outer peripheral surface is opposed to the latent image carrier. A toner carrier to be transported to a developing area which is a part;
Toner supply means for supplying toner to the outer peripheral surface of the toner carrier,
The toner supplied from the toner supply means by forming a hopping electric field on the outer peripheral surface of the toner carrying member for hopping the toner by applying different voltages to the at least two kinds of electrode members. Is carried on the outer peripheral surface of the toner carrier, and the toner carrier is moved to move the toner in a hopped state to the developing region and adhere to the latent image on the latent image carrier. The latent image is developed;
With respect to the surface movement direction of the toner carrier, the outer peripheral surface of the toner carrier at a position downstream of the supply position where the toner supply means supplies toner to the toner carrier and upstream of the development region In a developing device including a toner collecting member that collects a reversely charged toner contained in a toner in a hopped state opposite to the toner,
The toner recovery member is an endless moving body whose surface moves endlessly,
The toner collecting member adheres to the surface of the toner collecting member at a toner collecting position facing the toner carrying member, and collects the poorly charged toner including the reversely charged toner conveyed by the endless movement of the toner collecting member. A developing device comprising recovery member cleaning means for mechanically removing the surface of the member. The developing device according to claim 1.
The toner collecting member is not in contact with the toner carrier;
The recovery gap that is the distance between the toner recovery member and the toner carrier at the toner recovery position is set to be equal to or less than the development gap that is the distance between the latent image carrier and the toner carrier in the development region. A developing device. The developing device according to claim 1 or 2,
The developing device according to claim 1, wherein the toner collecting member moves on the surface so that a surface moving direction at the toner collecting position is opposite to a surface moving direction of the toner carrier. The developing device according to any one of claims 1 to 3,
2. A developing device according to claim 1, wherein the toner collecting member is a conductive member, and comprises a collecting bias applying means for applying a bias having the same polarity as the normally charged toner in the hopped toner to the toner collecting member. In an image forming apparatus that develops the latent image by attaching toner to the latent image of the latent image carrier, and finally transfers the toner image obtained thereby to a recording material to form an image.
An image forming apparatus using the developing device according to claim 1 as means for developing a latent image on the latent image carrier. A latent image carrier that carries a latent image, a developing unit that develops the latent image on the latent image carrier, a charging unit that charges the surface of the latent image carrier, and a surface for cleaning the latent image carrier And at least one of the latent image carrier, the charging unit, and the cleaning unit and the developing unit in the image forming apparatus including the cleaning unit configured to be held by a common holding unit as a unit with respect to the image forming apparatus main body. In the process cartridge configured to be detachable integrally,
5. A process cartridge using the developing device according to claim 1 as the developing means.

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