JP2013218320A - Developing device, process unit, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of insufficient image density during successive printing, while suppressing the occurrence of filming.SOLUTION: A developing device has a configuration to attach a toner retained in a recess 42b of a recess pattern of a developing roller 42 to an electrostatic latent image on a photoreceptor 2 to develop the electrostatic latent image, and includes: a supply roller 44 capable of contacting an area, of the entire area on the surface of the developing roller 42, before entering a regulation position to be in contact with a doctor blade 45 after passing a developing position α so as to transfer a toner attached to the above area to the supply roller 44 itself to recover the toner; and a recovery bias power source 144 that outputs recovery bias to be applied to the supply roller 44 so as to form an electric field between the developing roller 42 and the supply roller 44 to move toner from the developing roller 42 side to the supply roller 44 side.

Description

  The present invention relates to a developing device for developing a latent image on a surface of a latent image carrier with toner carried on an endlessly moving surface on which a predetermined concave pattern is formed on the developer carrier. The present invention also relates to a process unit and an image forming apparatus using such a developing device.

  Conventionally, as a developing roller as a developer carrying member, the surface has been subjected to a surface roughening process such as sandblasting with the aim of reliably transporting the toner carried on the surface (so-called one-component developer) following the surface movement. There is known a developing device using the same. However, this type of developing device has a problem that it easily causes image deterioration due to toner filming. Specifically, in the configuration using the developing roller subjected to the roughening treatment, the developing roller and the latent image carrier can be formed by maintaining a constant thickness of the thin toner layer formed on the surface of the developing roller. The developer conveyance amount is stabilized with respect to the development position where the photosensitive member faces. For this purpose, a regulating blade for regulating the thickness of the thin toner layer is pressed against the surface of the developing roller immediately before entering the developing position. In such a configuration, it is easy to cause a phenomenon called filming in which a toner applied with a large pressure between the developing roller and the regulating blade is fixed to the surface of the developing roller or the regulating blade to form a film of the fixed toner. When filming occurs, the thickness of the toner and the amount of charge vary, and image deterioration such as background smudges and white spots is caused.

  On the other hand, as described in Patent Document 1, Patent Document 2, and the like, a developing roller having a predetermined concave pattern formed on the surface is used, and the surface of the roller is controlled by a regulating member that is in contact with the roller surface. A developing device for scraping off the component developer is known. In this type of developing device, toner is filled in the concave portion on the roller surface, and the toner protruding from the upper end of the concave portion is scraped off by the regulating member, and the toner adhering to the non-concave portion on the roller surface is rubbed from the non-concave portion. Cut it. As a result, it is possible to transport the toner of almost the same amount as the capacity of the concave portion to the developing position, and to stabilize the developer transport amount to the developing position.

  In such a developing device, only the toner carried on the surface of the developing roller, which is present in the recess, passes through the position facing the regulating member and applies a large pressure when passing. Therefore, the occurrence of filming can be suppressed.

  However, this developing device may cause insufficient image density during continuous printing. Specifically, the remaining toner remaining in the recess of the developing roller after passing through the developing position may be filled with new toner without being collected. When the toner passes through the regulation position, the residual toner increases the frictional charge amount by being pressed with new toner. As a result, the electrostatic adhesion force with the developing roller is increased, so that it is difficult to transfer to the electrostatic latent image on the photosensitive member at the developing position. In continuous printing, the residual toner that is difficult to transfer to the electrostatic latent image increases with time in the concave portion, and eventually causes insufficient image density.

  The present invention has been made in view of the above background, and an object thereof is to provide the following developing device, a process unit using the same, and an image forming apparatus. That is, a developing device or the like that can suppress the occurrence of insufficient image density during continuous printing while suppressing the occurrence of filming.

  In order to achieve the above object, the present invention provides a developer carrying member for carrying toner on its surface on which a predetermined concave pattern is formed, and developer supply means for supplying toner to the surface of the developer carrying member. And after passing through a supply position facing the developer supply means in the entire area of the endlessly moving surface of the developer carrier, and before entering the development position facing the latent image carrier of the image forming apparatus. In a developing device having a regulating member that regulates the amount of toner conveyed to the developing position by contacting the region, and a developing bias output unit that outputs a developing bias to be applied to the developer carrier, The toner adhering to the region of the entire surface of the developer carrying member after contacting the region after passing the developing position and before entering the restricting position contacting the restricting member. In the recovery member to form an electric field for moving the toner from the developer carrier side to the recovery member side between the developer carrier and the recovery member. A recovery bias output means for outputting a recovery bias to be applied is provided.

In the present invention, the developer carrying member having a predetermined concave pattern is used to reduce the pressure on the toner when the toner carried on the developer carrying member is passed through the position facing the regulating member. Thus, the occurrence of filming can be suppressed.
Further, in the present invention, the residual toner in the concave portion of the developer carrying member is formed between the surface of the developer carrying member after passing through the developing position and before entering the regulation position, and the collecting member in contact with the surface. An electric field is formed for electrostatic movement from the inside toward the recovery member. Then, due to the action of this electric field, the residual toner is transferred from the inside of the recess to the surface of the recovery member and recovered. As described above, by actively collecting the residual toner from the concave portion of the developer carrier before entering the regulation position by the collecting member, an increase in the residual toner in the concave portion over time during continuous printing is suppressed. Thus, the occurrence of insufficient image density can be suppressed.

1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 2 is a schematic configuration diagram illustrating a photoconductor and a developing device of the copier. FIG. 2 is a perspective view showing the developing device. FIG. 4 is a perspective view showing the developing device from the opposite side of FIG. 3. FIG. The perspective view which shows the one end part of the longitudinal direction of the developing device. FIG. 3 is an exploded perspective view showing one end portion of the developing device in the longitudinal direction from the back side of the device. FIG. 3 is an exploded perspective view showing one end portion in the longitudinal direction of the developing device with the developing roller removed. FIG. 3 is an exploded perspective view showing the other end portion in the longitudinal direction of the developing device with the lower case removed. FIG. 3 is an exploded perspective view showing the other end portion in the longitudinal direction of the developing device with the developing roller removed. The perspective view which shows the developing roller. The front view which shows the developing roller. (A) is a whole schematic diagram showing the entire developing roller. (B) is an enlarged schematic view showing a part of the surface of the developing roller in an enlarged manner. (C) is a sectional view in which the developing roller is broken at a position of L11 or L13 in (b). (D) is sectional drawing fractured | ruptured in the position of L12 or L14 in (b). The perspective view which shows the supply roller of the developing device. The front view which shows the supply roller. The perspective view which shows the doctor blade of the developing device. The front view which shows the doctor blade. The perspective view which shows the paddle of the developing device. The front view which shows the paddle. FIG. 3 is an enlarged configuration diagram illustrating an example of a doctor unit of the developing device. The expansion block diagram which expands and shows the other example of the doctor part. 1 is a schematic configuration diagram showing a photoconductor and a developing device of a copying machine according to a first embodiment. The principal part block diagram which shows the principal part of the printer part of the copying machine which concerns on a 1st modification. FIG. 3 is a transverse cross-sectional view showing the process cartridge in the printer section, broken away in the vicinity of the central portion in the axial direction of the developing roller. FIG. 3 is a transverse cross-sectional view showing the process cartridge by being broken at a position of a side seal in the vicinity of an axial end portion. FIG. 3 is a longitudinal sectional view showing a toner conveying portion of the developing device of the process cartridge. FIG. 10 is a schematic configuration diagram showing a photoconductor and a developing device of a copying machine according to a second modification. FIG. 10 is a schematic configuration diagram showing a photoconductor and a developing device of a copying machine according to a third modification. The expanded block diagram for demonstrating the edge contact state of the counter direction in a doctor blade. The expanded block diagram for demonstrating the edge contact state of the forward direction in a doctor blade. FIG. 10 is a partially enlarged configuration diagram partially showing a developing device of a copying machine according to a second embodiment. FIG. 2 is an enlarged configuration diagram illustrating a developing roller and an entrance seal of the copier. 6 is a graph showing a waveform of a developing bias applied to the developing roller and a waveform of a recovery bias applied to an inlet seal. FIG. 9 is an enlarged configuration diagram illustrating a developing roller and an entrance seal of a copying machine according to a third embodiment. 6 is a graph showing a waveform of a developing bias applied to the developing roller of the copier and a waveform of a recovery bias applied to a conductive portion of the inlet seal.

Hereinafter, an embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine 500) as an image forming apparatus will be described.
FIG. 1 is a schematic configuration diagram illustrating a copying machine 500 according to the embodiment. The copying machine 500 includes a copying machine main body (hereinafter referred to as a printer unit 100), a paper feed table (hereinafter referred to as a paper feed unit 200), and a scanner (hereinafter referred to as a scanner unit 300) mounted on the printer unit 100.

  The printer unit 100 includes four process cartridges 1 (Y, M, C, and K) as process units and an intermediate transfer member that is stretched by a plurality of stretching rollers and moves in the direction of arrow A in FIG. A transfer belt 7, an exposure device 6 as an exposure unit, a fixing device 12 as a fixing unit, and the like are provided.

  The subscripts Y, M, C, and K added after the symbol 1 in the four process cartridges 1 indicate the specifications for yellow, magenta, cyan, and black. The four process cartridges 1 (Y, M, C, and K) have substantially the same configuration except that the colors of the toners to be used are different. Therefore, the subscripts K, Y, M, and C are omitted below. I will explain.

  The process cartridge 1 is a unit that integrally supports a photosensitive member 2 as a latent image carrier, a charging member 3 as a charging unit, a developing device 4 as a developing unit, and a photosensitive member cleaning device 5 as a cleaning unit. The configuration is shaped like Each process cartridge 1 can be attached to and detached from the copying machine 500 main body by releasing a stopper (not shown).

  The photoconductor 2 rotates in the clockwise direction in the figure as indicated by an arrow in the figure. The charging member 3 is a roller-shaped charging roller, is in pressure contact with the surface of the photoconductor 2, and is rotated by the rotation of the photoconductor 2. At the time of image formation, a predetermined bias is applied to the charging member 3 by a high voltage power source (not shown) to charge the surface of the photoreceptor 2. In the process cartridge 1 according to the embodiment, the roller-shaped charging member 3 that contacts the surface of the photoreceptor 2 is used as the charging unit. However, the charging unit is not limited to this, and non-contact such as corona charging. A charging method may be used.

The exposure device 6 exposes the surface of the photoconductor 2 on the surface of the photoconductor 2 based on the image information of the original image read by the scanner unit 300 or image information input from an external device such as a personal computer. An electrostatic latent image is formed. The exposure device 6 provided in the printer unit 100 uses a laser beam scanner system using a laser diode, but may have other configurations such as an exposure unit using an LED array.
The photoconductor cleaning device 5 cleans the transfer residual toner remaining on the surface of the photoconductor 2 that has passed the position facing the intermediate transfer belt 7.

  The four process cartridges 1 form toner images for the respective colors of yellow, cyan, magenta, and black on the photoreceptor 2. The toner images, which are arranged in parallel in the surface movement direction of the intermediate transfer belt 7, are transferred so that the toner images formed on the respective photoreceptors 2 are sequentially superimposed on the intermediate transfer belt 7, and can be transferred onto the intermediate transfer belt 7. Form a visual image.

  In FIG. 1, a primary transfer roller 8 serving as a primary transfer unit is disposed at a position facing each photoconductor 2 with the intermediate transfer belt 7 interposed therebetween. A primary transfer bias is applied to the primary transfer roller 8 by a high voltage power source (not shown) to form a primary transfer electric field with the photosensitive member 2. By forming a primary transfer electric field between the photosensitive member 2 and the primary transfer roller 8, the toner image formed on the surface of the photosensitive member 2 is transferred to the surface of the intermediate transfer belt 7. One of a plurality of stretching rollers that stretch the intermediate transfer belt 7 is rotated by a drive motor (not shown), so that the intermediate transfer belt 7 moves in the direction of arrow A in the figure. A full color image is formed on the surface of the intermediate transfer belt 7 by sequentially transferring the toner images of the respective colors on the surface of the intermediate transfer belt 7 moving on the surface.

  With respect to the position where the four process cartridges 1 are opposed to the intermediate transfer belt 7, the intermediate transfer belt 7 is located on the downstream side of the surface movement direction with respect to the secondary transfer counter roller 9a which is one of the stretching rollers. A secondary transfer roller 9 is disposed at a position opposed to the belt 7 and forms a secondary transfer nip with the intermediate transfer belt 7. A predetermined voltage is applied between the secondary transfer roller 9 and the secondary transfer counter roller 9a to form a secondary transfer electric field. A full-color image formed on the surface of the intermediate transfer belt 7 when the recording paper P fed from the paper feeding unit 200 and conveyed in the direction of arrow S in FIG. The image is transferred to the recording paper P by a secondary transfer electric field formed between the next transfer roller 9 and the secondary transfer counter roller 9a.

  A fixing device 12 is disposed downstream of the secondary transfer nip in the conveyance direction of the recording paper P. The recording paper P that has passed through the secondary transfer nip reaches the fixing device 12, the full color image transferred onto the recording paper P is fixed by heating and pressurization in the fixing device 12, and the recording paper P on which the image is fixed is It is discharged from the copying machine 500 to the outside of the machine.

  On the other hand, the toner remaining on the surface of the intermediate transfer belt 7 without being transferred to the recording paper P at the secondary transfer nip is collected by the transfer belt cleaning device 11.

  As shown in FIG. 1, above the intermediate transfer belt 7, toner bottles 400 (Y, M, C, K) that store toner of each color are detachably disposed on the copying machine 500 main body. The toner stored in each color toner bottle 400 is supplied to each color developing device 4 by a toner replenishing device (not shown) corresponding to each color.

  FIG. 2 is a schematic configuration diagram showing the developing device 4 of the copying machine according to the embodiment, and shows a view from the back side of the paper surface in FIG. FIGS. 3 and 4 are perspective views showing the developing device 4, respectively, and show views from different directions. In these drawings, the developing casing 41 forming the outer shape of the developing device 4 is formed by combining an upper case 411, an intermediate case 412, and a lower case 413. The middle case 412 forms a toner accommodating portion 43, and the upper case 411 is formed with a toner replenishing port 55 that is a developer replenishing portion that communicates the toner accommodating portion 43 with the outside. The upper case 411 is provided with an inlet seal 47 that seals a gap between the developing roller 42 and the upper case 411.

  FIG. 5 is a sectional view showing the developing device 4 from the same direction as FIG. FIG. 6 is a perspective view showing one end portion of the developing device 4 in the longitudinal direction. In these drawings, the middle case 412 is provided with a developing roller 42, a supply roller 44, a doctor blade 45, a paddle 46, a supply screw 48, a remaining toner sensor 49, and the like.

  The developing device 4 is provided with an opening 56 that communicates the inside and the outside along the longitudinal direction (Y-axis direction in the figure). The opening 56 is for exposing a part of the peripheral surface of the developing roller 42 to the outside of the developing device 4 and directly facing the photoreceptor 2. The position where the photosensitive member 2 and the developing roller 42 face each other with a minute gap is a developing position α.

  FIG. 7 is an exploded perspective view showing one end portion (the rear end portion in FIG. 1) of the developing device 4 in the longitudinal direction. The developing device 4 shown in FIG. 7 has a lower case (413) removed. FIG. 8 is an exploded perspective view showing one end portion in the longitudinal direction of the developing device 4 with the developing roller removed. FIG. 9 is an exploded perspective view showing the other end portion in the longitudinal direction (front end portion in FIG. 1) of the developing device 4 with the lower case removed. FIG. 10 is an exploded perspective view showing the other end in the longitudinal direction of the developing device 4 with the developing roller removed.

  In these drawings, in the developing device 4, the supply roller 44 rotates in the direction of arrow C in FIG. 2 (clockwise direction in FIG. 2) and moves on the surface, thereby developing the toner T in the toner containing portion 43. The toner is supplied to the surface of the developing roller 42 by being conveyed to a supply nip β that is a region facing the roller 42. The developing roller 42 carries the supplied toner on the surface, rotates in the direction of arrow B in FIG. 2 (clockwise direction in FIG. 2), and moves on the surface, thereby removing the toner on the developing roller 42. The toner is conveyed to a portion facing the doctor blade 45 that is regulated to a predetermined amount. The doctor blade 45 is opposed to the developing roller 42 and is in a counter direction with respect to the surface movement direction of the developing roller 42 (the tip of the doctor blade 45 is upstream of the rotation direction of the developing roller 42 with respect to the base of the doctor blade 45). The toner that is in contact with the doctor blade 45 and restricted to a predetermined amount at the portion facing the doctor blade 45 reaches the developing position α that faces the photoreceptor 2 through a minute gap as the developing roller 42 rotates. .

  In the supply nip β, the surface of the supply roller 44 moves from below to above, and the surface of the developing roller 42 moves from above to below. The supply roller 44 and the developing roller 42 are in contact with each other at the supply nip β.

  At the developing position α, the toner T on the surface of the developing roller 42 is generated according to the developing electric field formed by the potential difference between the developing bias applied from the developing bias power source 142 to the developing roller 42 and the latent image on the surface of the photoreceptor 2. Moves to the surface of the photosensitive member 2, toner adheres to the electrostatic latent image portion on the surface of the photosensitive member 2, and development is performed. The photoreceptor 2 rotates in the direction of arrow D in FIG. 2 without contact with the developing roller 42. For this reason, at the development position α, the surface movement direction of the developing roller 42 and the surface movement direction of the photoreceptor 2 are the same direction.

  The development bias power supply 142 is configured to develop a latent image with the toner conveyed to the development position α, and a first voltage for directing the toner from the developing roller 42 to the photosensitive member 2, and from the photosensitive member 2 to the developing roller 42. A voltage applying unit that applies an alternating voltage having a second voltage for directing the toner to the developing roller.

  As will be described in detail later, the surface of the developing roller 42 has a regular uneven shape with a substantially constant height of the flat portion 42a as a non-recessed portion and a depth of the recessed portion 42b over the entire outer peripheral surface. ing. The toner T on the surface of the developing roller 42 that has not contributed to the development at the development position α and has passed the development position α is collected by the supply roller 44 at the upstream side in the rotation direction of the development roller 42 in the supply nip β, and developed. The surface of the roller 42 is reset. That is, the supply roller 44 also has a role as a collection roller.

  The toner T carried in the concave portions 42b regularly formed on the surface of the developing roller 42 is difficult to be collected. When the toner T that has passed the developing position α passes through the supply nip β and remains carried on the developing roller 42, the toner T adheres to the developing roller 42 and toner filming occurs. When toner filming occurs, the charge amount per unit weight of the toner T on the developing roller 42 and the toner amount per unit area of the developing roller 42 become unstable, causing density unevenness during development.

  In the supply nip β where the developing roller 42 and the supply roller 44 face each other, the surface movement direction of the development roller 42 and the surface movement direction of the supply roller 44 are opposite to each other. As a result, the linear velocity difference between the surface of the developing roller 42 and the surface of the supply roller 44 at the supply nip β increases, and the recovery performance of the supply roller 44 at the supply nip β can be improved. Therefore, it is possible to suppress the toner from being held on the developing roller 42, to suppress the toner from adhering to the surface of the developing roller 42, and to cause the developer to adhere to the surface of the developer carrying member. The occurrence of density unevenness during development can be suppressed.

  The linear speed ratio between the developing roller 42 and the supply roller 44 is the surface moving speed of the developing roller 42: the surface moving speed of the supply roller 44 = 1: 0.85, but the linear speed ratio is limited to this value. It is not a thing.

  As shown in FIG. 2, the supply roller 44 is disposed on the upper portion of the toner storage portion 43, and at least a part of the supply roller 44 is from the surface of the toner T in the toner storage portion 43 in a state where the rotation of the paddle 46 is stopped. Is also located above. An area downstream of the supply nip β in the surface movement direction of the supply roller 44 (hereinafter referred to as a supply nip downstream area) is located above the surface of the toner T. When the toner is filled in the downstream area of the supply nip as in the configuration shown in FIG. 4 of Patent Document 1, the toner filled in the downstream area of the supply nip is replaced with new toner in the downstream area of the supply nip. This may hinder entry of toner and reduce the efficiency of collecting toner from the developing roller 42 in the supply nip β. On the other hand, in the developing device 4 according to the embodiment, as shown in FIG. 2, the region on the downstream side of the supply nip is located above the surface of the toner T, so Is not filled, and the toner existing in the downstream area of the supply nip does not hinder the collection of the toner from the developing roller 42 in the supply nip β. For this reason, the toner can be efficiently collected and the resetting property of the toner can be improved.

  Next, the developing roller 42 will be described. FIG. 11 is a perspective view showing the developing roller 42. FIG. 12 is a front view showing the developing roller 42. FIG. 13 is a diagram for explaining the surface shape of the developing roller 42. Specifically, FIG. 13A is an overall schematic diagram showing the entire developing roller 42. FIG. 13B is an enlarged schematic view showing a part of the surface of the developing roller 42 in an enlarged manner. FIG. 13C is a cross-sectional view in which the developing roller 42 is broken at a position L11 or L13 in FIG. 13B. Moreover, FIG.13 (d) is sectional drawing fractured | ruptured in the position of L12 or L14 in FIG.13 (b).

  In these drawings, the developing roller 42 has a configuration in which a developing roller cylindrical portion 420 that carries toner on the surface thereof is provided on the developing roller shaft 421, and both axial end portions that are axially outside the developing roller cylindrical portion 420. A spacer 422 is provided on the developing roller shaft 421 in the vicinity. The developing roller 42 is provided so as to be rotatable about the developing roller shaft 421, and is arranged so that the axial direction of the developing roller shaft 421 is parallel to the longitudinal direction (Y-axis direction in the drawing) of the developing device 4. Yes. Both ends of the developing roller shaft 421 in the axial direction of the developing roller 42 are rotatably attached to the side wall portion 412s of the middle case 412. A part of the surface of the developing roller 42 is exposed to the outside of the developing device 4 from the opening 56, and the developing roller 42 is moved from the lower side to the upper side to convey the toner so that the toner is conveyed in FIG. It rotates in the direction of arrow B.

  Further, in the developing roller 42, the distance between the surface of the developing roller cylindrical portion 420 and the surface of the photosensitive member 2 at the developing position α is obtained by the spacers 422 provided in the vicinity of both ends in the axial direction coming into contact with the surface of the photosensitive member 2. (Development gap) is kept constant. The base material of the developing roller 42 is made of a metal material sleeve such as an aluminum-based material such as 5056 aluminum alloy or 6063 aluminum alloy or an iron-based material such as STKM. A surface layer is formed on the outer peripheral surface of the substrate. The developing roller 42 is provided with an uneven surface on the surface of the metal material sleeve as a base material, and nickel plating is applied to the metal material sleeve subjected to the uneven surface processing, thereby preventing corrosion of the developing roller 42 and toner. A surface layer for assisting charging is formed.

  As shown in FIG. 13A, the developing roller cylindrical portion 420 of the developing roller 42 is mainly divided into two portions (a groove forming portion 420a and a non-groove forming portion 420b) based on the difference in the structure of the surface. It is done. The groove forming portion 420a is a portion including a central portion in the axial direction of the developing roller 42, and is provided with a concavo-convex process on the surface thereof in order to properly carry the toner. As the concavo-convex processing, so-called rolling processing is adopted, and the flat portion 42a is formed surrounded by spiral first grooves L1 and second grooves L2 having different winding directions. By forming spiral grooves with different winding directions, irregularities on the mesh are formed on the surface of the developing roller 42. As the rolling process, a conventionally known processing method can be employed. Further, the first groove L1 and the second groove L2 are each a predetermined angle with respect to the axial direction of the developing roller 42 (in the embodiment, both L1 and L2 are 45 [°], but are not limited thereto. ).

  Both the first groove L1 and the second groove L2 are periodically formed with a predetermined periodic width in the inclined direction, so that the flat surface portion 42a is formed with an axial pitch width W1. In addition, the first groove L1 and the second groove L2 can have different inclination angles and periodic widths. Further, the axial length W2 of the top surface 42t of the flat portion 42a is formed to be not less than 1/2 of the pitch width W1.

  The pitch width W1 in the axial direction of the flat surface portion 42a in the developing roller 42 is 80 [μm], and the axial length W2 of the top surface 42t of the flat surface portion 42a is 40 [μm]. The recess depth W3, which is the height from the recess 42b to the top surface 42t of the flat surface 42a, is 10 [μm]. The values of the pitch width W1, the axial length W2 of the top surface 42t, and the recess depth W3 are merely examples, and are not limited to these values.

  The material of the surface layer 42f of the developing roller 42 is desirably a material that normally charges the toner. Even when the low-charged toner is produced by the filming, the low-charged toner knocked out by the jumped toner T can be charged at a portion where the filming of the flat portion 42a or the concave portion 42b does not occur. It can be reduced and the image density is stabilized. In the developing roller 42 of the embodiment, the surface layer 42f is a material that normally charges the toner by applying nickel plating.

  The material of the surface layer 42f of the developing roller 42 is desirably harder than the doctor blade 45 (blade member 450). This makes it difficult for the flat surface portion 42a on the surface of the developing roller 42 to be scraped by the doctor blade 45, so that the volume of the concave portion 42b surrounded by the flat surface portion 42a and the doctor blade 45 is difficult to change, and the M / A value (on the surface of the developing roller) The amount of toner carried per unit area) is stabilized.

  The height of the flat portion 42a of the developing roller 42 is desirably larger than the weight average particle diameter of the toner T to be used. Since the toner T having an average size is accommodated in the recess 42b, the selection of the particle size is difficult to occur, and the M / A value (the amount of toner carried per unit area on the surface of the developing roller) is stabilized over time. .

  Next, the supply roller 44 will be described. FIG. 14 is a perspective view showing the supply roller 44. FIG. 15 is a side view showing the supply roller 44. In these drawings, inside the developing device 4, a cylindrical supply roller 44 is provided on the developing roller 42 side above the toner containing portion 43. The supply roller 44 has a configuration in which a cylindrical foam material is wound around a supply roller shaft 441 that is a shaft portion thereof, and the cylindrical foam material becomes a supply roller cylindrical portion 440 that carries toner on the surface thereof. .

  The supply roller 44 is configured to be rotatable about the supply roller shaft 441 and is attached to the side wall portion 412 s of the middle case 412 so as to be rotatable. The supply roller 44 is disposed such that a part of the outer peripheral surface of the supply roller cylindrical portion 440 is in contact with the outer peripheral surface of the developing roller cylindrical portion 420 of the developing roller 42 at the supply nip β. As shown, the supply roller shaft 441 is disposed above the developing roller shaft 421.

  The supply roller 44 rotates so that the surface thereof moves in a direction opposite to the surface movement direction of the developing roller 42 at a supply nip β that is a portion facing the developing roller 42. Further, as shown in FIG. 2, the developing device 4 is arranged such that the position of the supply nip β is located above the contact position of the doctor blade 45 with respect to the developing roller 42.

  The supply roller cylindrical portion 440 of the supply roller 44 is made of a foam material. In the supply roller cylindrical portion 440, the surface layer in contact with the developing roller 42 is a sponge layer in which a large number of micropores are dispersed on the surface. By making the surface layer of the supply roller 44 into a sponge shape, the supply roller 44 can easily reach the bottom of the recess 42b, so that the resetability of the toner on the developing roller 42 is improved.

  The amount of biting of the supply roller 44 with respect to the development roller 42 (“radius of the development roller 42” + “radius of the supply roller 44” − “distance between the axes of the development roller 42 and the supply roller 44”) is a flat portion of the development roller 42. It is larger than the height of 42a. By making the amount of biting of the supply roller 44 larger than the height of the flat surface portion 42a, it is possible to improve the toner resetting property in the concave portion 42b. Note that if the amount of biting of the supply roller 44 with respect to the developing roller 42 is too large relative to the height of the flat surface portion 42a, the toner will be pushed into the recess 42b and cause aggregation, so the amount of biting will not be too large. It is necessary to set as follows.

The foaming material used for the supply roller cylindrical portion 440 of the supply roller 44 has an electric resistance adjusted to a range of 10 ³ to 10 ¹⁴ [Ω]. A supply bias is applied to the supply roller 44 by a supply bias power supply 144 to assist the operation of pressing the toner preliminarily charged at the supply nip β against the developing roller 42. The supply roller 44 rotates in the clockwise direction in FIGS. 2 and 5 to apply and supply the developer adhered on the surface to the surface of the developing roller 42.

  The developing bias composed of an alternating voltage applied to the developing roller 42 has a central value (average value per unit time) of the same polarity as the normal charging polarity of the toner (in this example, a negative polarity). The supply roller 44 supplies the toner held in the plurality of air bubbles present on the surface to the developing roller 42 at the supply nip β. In the supply nip β, the surface of the developing roller 42 and the direction of the supply roller 44 move in the counter direction. In the supply nip β, the toner that has moved from the air bubbles on the surface of the supply roller 44 to the recess 42b of the developing roller 42 is scraped off by the sliding of both rollers. Then, at the outlet of the supply nip β, the toner in the recess 42 b moves with the developing roller 42 following the surface movement of the developing roller 42 as it is. A supply bias may be applied to the supply roller 44 by a supply bias power supply 144.

  Next, the doctor blade 45 will be described. As shown in FIGS. 5 to 10, a doctor blade 45 is provided in the middle case 412 that is located below the developing roller 42 and inside the lower case 413. FIG. 16 is a perspective view showing the doctor blade 45. FIG. 17 is a front view showing the doctor blade 45. In these drawings, the doctor blade 45 includes a blade member 450 that is a thin plate-like metal member that constitutes a regulating member, and a metal base portion 452 to which one end of the blade member 450 is fixed. The other end side of the blade member 450 is configured to come into contact with the developing roller 42. The contact state of the blade member 450 with respect to the developing roller 42 may be any of a tip contact state in which the tip contacts (edge contact described later) and a stomach contact state in which a surface portion on the base side from the tip contacts. However, in the tip contact state, the toner present on the top surface 42t of the flat surface portion 42a can be worn out, and only the toner present in the concave portion 42b is transported to the development position α to be transported to the development position α. This is more preferable because the toner amount is stable.

  As shown in FIG. 29, the edge pad contacts the front edge of the doctor blade 45 that forms a ridge line between the opposing surface of the developing roller 42 and the blade front end surface with the surface of the developing roller 42. It is a state to be made. At the leading edge forming the ridge line, the ridge line may be rounded or chamfered. In the doctor blade 45, there is an intersection of a virtual line extending the surface facing the developing roller 42 toward the blade tip and a virtual line extending the blade tip surface toward the developing roller 42, or a blade portion that is in the vicinity thereof. The tip edge. More specifically, a corner (which may be rounded or chamfered) on the developing roller 42 side at the free end of the flat doctor blade 45 may be a flat surface that is a non-recessed portion of the developing roller 42. It is a part which contacts a part (42a).

  As the edge contact direction, the counter direction is adopted among the counter direction and the forward direction. As shown in FIG. 29, the counter direction is such that the fixed portion on the fixed end side of the doctor blade 45 that is cantilevered is more rotated than the contact portion of the doctor blade 45 with the developing roller 42. Direction of the blade positioned on the downstream side. In this orientation, the surface of the developing roller 42 immediately before entering the contact position with the doctor blade 45 with rotation moves toward the tip edge on the free end side of the doctor blade 45, and the doctor blade 45 Of the entire area, the first edge contacts the leading edge on the free end side.

  On the other hand, in the forward direction, as shown in FIG. 30, the fixed portion on the fixed end side of the doctor blade 45 that is cantilevered is placed on the developing roller 42 more than the contact portion of the doctor blade 45 with the developing roller 42. This is the direction of the blade located upstream in the rotational direction. In this orientation, the surface of the developing roller 42 immediately before entering the contact position with the doctor blade 45 as it rotates is the portion of the entire area of the doctor blade 45 that is closer to the fixed end than the front end edge on the free end side ( The first part of the blade will contact the belly part of the blade.

  The blade member 450 of the doctor blade 45 is fixed to the pedestal portion 452 by a plurality of rivets 451. The pedestal portion 452 is made of a metal that is thicker than the blade member 450 and functions as a substrate for fixing the blade member 450 to the main body of the developing device 4 (side surface portion of the middle case 412). A pin hole 454 is provided at the longitudinal end of the pedestal portion 452, one is a perfect circular main reference hole 454 a, and the other is an elliptical secondary reference hole having a long diameter in the direction of the main reference hole 454 a. 454b. When a pin (not shown) enters the main reference hole 454a, the position of the pedestal portion 452 with respect to the main body of the developing device 4 is determined and supported by the sub reference hole 454b. The pedestal portion 452 to which the blade member 450 is fixed is fixed to the developing device 4 main body (inner case 412) with a doctor fixing screw 455, whereby the blade member 450 is fixed to the developing device 4.

  The blade member 450 of the doctor blade 45 is made of a metal leaf spring material such as SUS304CSP, SUS301CSP, or phosphor bronze. The blade member 450 abuts the free end side against the surface of the developing roller 42 with a pressing force of 10 to 100 [N / m], and regulates the toner passing under the pressing force to a predetermined amount. Charge is applied by triboelectric charging. Note that a bias may be applied to the blade member 450 from a doctor bias power source 145 in order to assist frictional charging.

  In addition, it is desirable to use a conductive member as the blade member 450 of the doctor blade 45. Since the blade member 450 is conductive, the charge amount of the toner T having a large Q / M value (charge amount per unit volume) can be lowered, and the Q / M value of the toner T can be made uniform. it can. Thereby, sticking of the toner T to the developing roller 42 can be prevented.

  The voltage applied to the blade member 450 by the doctor bias power supply 145 is ± 200 [V] with respect to the center value of the alternating voltage applied to the developing roller 42 (time average value when the duty is 50%). A DC voltage having a value shifted in the range can be exemplified. The value of the DC voltage may be controlled according to the use environment. Thereby, it is possible to suppress fluctuations in the M / A value (toner carrying amount per unit area on the surface of the developing roller) due to environmental fluctuations.

  Next, the paddle 46 will be described. A toner accommodating portion 43 is provided in the developing device 4 as a space for accommodating toner, and a paddle 46 is rotatably attached to the developing casing 41 in the toner accommodating portion 43. FIG. 18 is a perspective view showing the paddle 46. FIG. 19 is a front view showing the paddle 46. In these drawings, the paddle 46 includes a paddle shaft 461 that is a shaft portion thereof, and a paddle wing 460 as a thin wing member made of an elastic sheet material such as Mylar. The paddle shaft 461 has two flat portions facing each other, and paddle blades 460 are respectively attached to the two flat portions. The two paddle blades 460 are fixed to the flat portion of the paddle shaft 461 so as to protrude in opposite directions around the paddle shaft 461.

  A plurality of holes are arranged in the base portion of the paddle blade 460 so as to be parallel to the axial direction of the paddle shaft 461. On the peripheral surface of the paddle shaft 461, a plurality of spatula portions for fixing the paddle blades 460 to the paddle shaft 461 are projected. On the other hand, the paddle feather 460 is provided with a plurality of holes for penetrating the spatula portions. The paddle blade 460 is fixed to the paddle shaft 461 by performing a heat bending process with the spatula portion penetrating the hole.

  The paddle 46 is disposed so that the axial direction of the paddle shaft 461 is parallel to the longitudinal direction of the developing device 4 (Y-axis direction in the figure). Both ends in the axial direction of the paddle shaft 461 are rotatably attached to the side wall portion 412s of the middle case 412.

The amount of protrusion of the paddle blade 460 is set so that the paddle 46 has such a length that the tip of the paddle blade 460 extending from the paddle shaft 461 contacts the inner wall surface of the toner containing portion 43. As shown in FIGS. 2 and 5, the bottom surface portion 43 b of the toner accommodating portion 43 has an arc shape along the rotation direction of the paddle 46, and the paddle blade 460 accommodates the toner by the rubbing operation accompanying the rotation of the paddle 46. The bottom portion 43b of the portion 43 is not caught.
A side wall surface portion 43 s that rises perpendicularly from the bottom surface portion 43 b is formed on the developing roller 42 side of the toner containing portion 43. It is horizontal in the direction toward the roller and forms a step 50.

  The distance between the side wall surface portion 43s and the paddle shaft 461 is set shorter than the distance between the bottom surface portion 43b and the paddle shaft 461. Therefore, the paddle blade 460 that has rubbed the bottom surface portion 43b hits the side wall surface portion 43s and bends more greatly. Thereafter, when the tip of the paddle wing 460 reaches the stepped portion 50, there is nothing to hold the paddle wing 460, and the tip of the paddle wing 460 is released and jumps upward. By such movement of the paddle blade 460, the toner is splashed upward, and is stirred, conveyed, and supplied.

  The step portion 50 is a horizontal plane parallel to the XY plane, and is formed to extend in the longitudinal direction of the developing device 4 (Y-axis direction in the drawing). In the developing device 4 of the embodiment, the step portion 50 is provided in the entire region in the width direction, but may be provided in a part of the developing device 4 as long as the paddle blades 460 jump up.

  The supply screw 48 is a screw member that becomes a supply screw shaft 481 and a supply screw blade portion 480 that is a spiral blade portion fixed to the supply screw shaft 481. The supply screw shaft 481 is provided so as to be rotatable around the supply screw shaft 481. The supply screw shaft 481 is arranged so that the axial direction of the supply screw shaft 481 is parallel to the longitudinal direction of the developing device 4 (Y-axis direction in the drawing). Both axial ends of the supply screw shaft 481 are rotatably attached to the side wall portion 412 s of the middle case 412.

  The axial end of the supply screw 48 is positioned below a toner supply port 55 formed at the longitudinal end of the developing device 4. Then, when the supply screw 48 is rotated, the spiral supply screw blade 480 conveys the toner replenished from the toner replenishing port 55 toward the center of the developing device 4 in the longitudinal direction.

  An inlet seal 47 made of a sheet member such as Mylar is attached to the edge portion forming the opening 56 of the upper case 411 along the longitudinal direction. The inlet seal 47 is a substantially rectangular sheet, one end of which is affixed to the edge portion of the upper case 411, and the other end is a free end. The free end side of the inlet seal 47 protrudes toward the inside of the developing device 4, and is further provided so as to contact the developing roller 42. The inlet seal 47 is fixed to the upper case 411 on the upstream side in the rotational direction of the developing roller 42, and the downstream side in the rotational direction of the developing roller 42 is a free end, and the surface portion of the inlet seal 47 contacts the developing roller 42. It is arranged to do. Further, the inner side of the developing device 4 of the upper case 411 is curved so as to follow the upper shape of the supply roller 44, and the gap between the curved surface of the upper case 411 and the surface of the supply roller 44 is 1 0.0 [mm].

  As shown in FIGS. 7 to 10, side seals 59 are attached to a part of the middle case 412 corresponding to both longitudinal ends of the opening 56 of the developing device 4. The side seal 59 is provided on the inner side in the axial direction with respect to the spacer 422 provided in the vicinity of both ends in the axial direction of the developing roller 42, and in a region where the axial end where the doctor blade 45 contacts the developing roller 42 overlaps. ing. Such a side seal 59 prevents the toner from leaking from the end portion in the longitudinal direction of the opening 56 in the developing casing 41. A remaining toner sensor 49 provided in the middle case 412 detects the amount of toner in the toner storage unit 43.

  Next, the movement of toner in the developing device 4 will be described. The toner replenished into the developing device 4 from the toner replenishing port 55 is supplied to the toner accommodating portion 43 by the supply screw 48 and stirred by the paddle 46. Further, the paddle 46 is flipped up in the direction of the developing roller 42 and the supply roller 44 and conveyed. The toner supplied to the supply roller 44 is delivered to the surface of the developing roller 42 at a supply nip β where the supply roller 44 contacts the developing roller 42. Of the toner delivered to the surface of the developing roller 42, the amount of toner exceeding a predetermined amount conveyed to the developing position α is scraped off from the surface of the developing roller 42 by the doctor blade 45.

  The toner remaining on the surface of the developing roller 42 that has passed through the portion facing the doctor blade 45 is conveyed as it is by the surface moving method by the rotation of the developing roller 42, and reaches the developing position α facing the photoreceptor 2. The toner that has passed through the development position α without being used for development passes through the position where the inlet seal 47 contacts, and is conveyed to the supply nip β that is the position facing the supply roller 44. The toner that has reached the supply nip β by the developing roller 42 is scraped off from the surface of the developing roller 42 by the supply roller 44 and conveyed by the supply roller 44.

  The toner stored in the toner storage chamber 101 is manufactured by a polymerization method, and the average particle diameter thereof is about 6.5 [μm]. The circularity is about 0.98, and the angle of repose is about 33 [°]. It contains strontium titanate as an external additive. The toner used in the developing device according to the present invention is not limited to this.

  On the surface of the developing roller 42 of the developing device 4, a regular concave pattern having a constant convex height and concave depth (W 3) is formed. As a conventional one-component developing device, there is one in which a rough surface process such as a sound blast process is performed on the surface of a developing roller to form an uneven shape on the surface. The surface of the developing roller is roughened to improve the toner carrying performance and toner transport performance of the developing roller. However, the minute unevenness formed on the surface of the developing roller by the roughening treatment has irregularities in the height of the protrusion, the depth of the recess, and the unevenness pattern. If the irregular pattern and depth are irregular, the toner carrying amount on the surface of the developing roller is not stable, and density unevenness may occur when the latent image on the photosensitive member is developed. On the other hand, in the developing device 4 of the embodiment, since the depth (W3) of the recess is constant and the formation pattern is regular, the toner carrying amount on the surface of the developing roller 42 is stabilized, and density unevenness during development is reduced. Occurrence can be suppressed.

  As shown in FIGS. 1 and 20, in the developing device according to the embodiment, the developing roller 42 that rotates in the direction of arrow B in the drawing moves downward from above in the doctor portion. In such a case, a downward force (Fg) is applied to the toner by its own weight acting on the toner T, so that the compressive force on the toner due to the stress (Fb) of the doctor blade 45 can be reduced. Therefore, it is possible to suppress the toner from aggregating at a portion (a portion 42c in FIG. 20) of the convex portion 42a of the developing roller 42 on the downstream side in the surface movement direction of the developing roller 42. As a result, the occurrence of filming can be suppressed, and fluctuations in the Q / M value and M / A value on the developing roller 42 can be suppressed.

  Further, as the toner that is a developer used in the developing device 4, a toner having an acceleration aggregation degree of 40% or less is used, so that a portion of the convex portion 42 a of the developing roller 42 on the downstream side in the surface movement direction of the developing roller 42 It is possible to further alleviate the aggregation of toner at (a portion 42c in FIG. 20). In the doctor section shown in FIG. 20, the doctor blade 45 is placed against the surface of the developing roller 42. As shown in FIG. 21, the contact state of the doctor blade 45 with the surface of the developing roller 42 allows the toner T present on the top surface 42t of the convex portion 42a to be worn off when the tip blade is in contact. More preferable.

Next, a characteristic configuration of the copier according to the embodiment will be described.
In FIG. 2 shown above, the recovery brush roller 51 is applied to the entire area of the peripheral surface of the developing roller 42 after passing through the developing position and before entering the contact position with the supply roller 44. While being in contact, it is driven to rotate clockwise in the figure. The collection brush roller 51 is formed by forming a brush portion made of a plurality of conductive brushes on the peripheral surface of a metal shaft member.

  The conductive raising of the brush portion of the collecting brush roller 51 causes its tip portion to enter the recess (42b) of the developing roller 42 as it rotates, and scrapes the residual toner remaining in the recess from the recess. . As shown in the drawing, at the contact portion between the developing roller 42 and the collection brush roller 51, the surfaces of the two move in the counter direction, so that the conductive brushing of the collection brush roller 51 causes more than the movement in the forward direction. The effect of scraping residual toner from the inside of the recess can be enhanced.

  The following alternating voltage is applied to the developing roller 42 as a developing bias by a developing bias power source 142. That is, with respect to an alternating voltage composed of a rectangular wave having a peak-to-peak voltage Vpp = 1.7 [kV], a positive side peak = + 8.5 [kV], and a negative side peak = −8.5 [kV], −300 It is an alternating voltage on which a DC voltage of [V] is superimposed. The frequency of the rectangular wave is 500 [Hz]. The duty of the rectangular wave is 50 [%]. Therefore, the average value of the alternating voltage per unit time is −300 [V]. In addition, the center value of the alternating voltage (the peak-to-peak center) is also −300 [V].

  On the other hand, the following alternating voltage is applied to the recovery brush roller 51 by the recovery bias power source 52. That is, with respect to an alternating voltage composed of a rectangular wave having a peak-to-peak voltage Vpp = 1.7 [kV], a positive side peak = + 8.5 [kV], and a negative side peak = −8.5 [kV], −200 It is an alternating voltage on which a DC voltage of [V] is superimposed. The frequency of the rectangular wave is 500 [Hz]. The duty of the rectangular wave is 50 [%]. Therefore, the average value of the alternating voltage per unit time is −200 [V]. The central value of this alternating voltage is also −200 [V].

  Since the normal charging polarity of the toner is negative, the average value (−200 V) of the recovery bias per unit time is a polarity opposite to the charging polarity of the toner than the average value (−300 V) of the developing bias per unit time. The value is shifted to the side. Due to such a potential relationship, the negatively charged residual toner remaining in the concave portion of the developing roller 42 at the contact portion between the developing roller 42 and the collecting brush roller 51 from the developing roller 42 side. An electric field for electrostatic movement is formed on the collection brush roller 51 side. The residual toner scraped out from the concave portion of the developing roller 42 by the conductive brushing of the brush portion of the collecting brush roller 51 is electrostatically adsorbed to the conductive brushing by the electric field. Thus, the residual toner is actively transferred from the concave portion of the developing roller 42 to the brush portion of the collecting brush roller 51 and collected, thereby suppressing an increase in the residual toner in the concave portion with time during continuous printing. The occurrence of insufficient image density can be suppressed.

  The collection brush roller 51 is in contact with the supply roller 44 in addition to being in contact with the developing roller 42. Residual toner that has been scraped from the recess of the developing roller 42 and transferred to the collecting brush roller 51 enters the contact portion between the collecting brush roller 51 and the supply roller 44. Then, after the transition from the collection brush roller 51 to the supply roller 44, the toner is returned to the toner in the toner storage unit 43.

  Note that the recovery bias power source 52 serving as a recovery bias output unit may be configured to output a recovery bias including only a DC voltage. In this case, a DC voltage having a value shifted from the average value of the developing bias per unit time to the polarity opposite to the charging polarity of the toner may be output. Further, the conditions for the development bias and the recovery bias are not limited to those described so far. As a frequency, the range of = 500-10000 [Hz] can be illustrated. Moreover, as a duty, the range of 50-90 [%] can be illustrated.

  Instead of the collection brush roller 51, a collection foam roller in which a conductive foam elastic layer is coated on the surface of a metal core may be used as the collection member. The recovery foam roller bites into the concave portion of the developing roller 42 while elastically deforming the conductive foam elastic layer at the contact portion with the developing roller 42. Then, the residual toner can be scraped out well from the inside of the concave portion by the conductive foamed elastic layer.

Next, an example copier in which a more characteristic configuration is added to the copier according to the embodiment will be described. Unless otherwise specified, the configuration of the copying machine according to each example is the same as that of the embodiment.
[First embodiment]
FIG. 22 is a schematic diagram showing the photoconductor and developing device of the copying machine according to the first embodiment. In the copying machine according to the first embodiment, a dedicated collecting member for collecting the residual toner from the concave portion of the developing roller 42 is not provided. Instead, a supply roller 44 composed of a foam roller having a metal core and a conductive elastic foam layer coated on the peripheral surface thereof is also used as a recovery foam roller as a recovery member. As a power source for outputting a bias to be applied to the supply roller 44, a recovery bias power source 52 is provided instead of the supply bias power source.

  The development bias power supply 142 outputs the following alternating voltage as the development bias. That is, with respect to an alternating voltage composed of a rectangular wave having a peak-to-peak voltage Vpp = 1.7 [kV], a positive side peak = + 8.5 [kV], and a negative side peak = −8.5 [kV], −300 It is an alternating voltage on which a DC voltage of [V] is superimposed. The frequency of the rectangular wave is 500 [Hz]. The duty of the rectangular wave is 50 [%]. The average value and the center value of the alternating voltage per unit time are both −300 [V].

  The recovery bias power supply 52 outputs the following alternating voltage as the recovery bias. That is, with respect to an alternating voltage composed of a rectangular wave having a peak-to-peak voltage Vpp = 1.7 [kV], a positive side peak = + 8.5 [kV], and a negative side peak = −8.5 [kV], −200 It is an alternating voltage on which a DC voltage of [V] is superimposed. The frequency of the rectangular wave is 500 [Hz]. The duty of the rectangular wave is 50 [%]. The average value and the center value of the alternating voltage per unit time are both −200 [V].

  In a conventional one-component developing device, the supply bias applied to the supply member is a value in which the average value with unit time is shifted to the same polarity side as the toner charging polarity with respect to the average value of the developing bias per unit time. It was configured to output something. By such a supply bias, an electric field for electrostatically moving the toner from the supply member side to the development roller side is formed between the supply member and the development roller, thereby facilitating transfer of the toner from the supply member to the development roller. It is.

  On the other hand, in the copier according to the first embodiment, instead of applying a supply bias to the supply roller 44 as a supply member, the above-described recovery bias is applied. The collection bias forms an electric field that electrostatically moves negatively charged toner from the developing roller 42 side to the supplying roller 44 side between the supplying roller 44 and the developing roller 42, contrary to the supplying bias. . Nevertheless, the toner is supplied from the supply roller 44 to the developing roller 42 for the reason described below.

  In the copying machine according to the embodiment and the first example, the concave portion of the developing roller 42 is formed with a large depth that forms a step that is considerably larger than the minute unevenness caused by the roughening process. The non-concave portion on the surface of the developing roller 42 hardly carries toner (slips), and the toner filled in the concave portion contributes to development. The supply roller 44 holds a relatively large amount of toner in the air bubbles of the conductive foam layer. Then, a large amount of toner is supplied to the concave portion of the developing roller 42 at the supply nip β which is a contact portion with the developing roller 42. In the supply nip β, an electric field for electrostatically moving the toner from the developing roller 42 side to the supply roller 44 side is formed. However, the electric field causes most of the toner in the recesses to return to the empty bubbles of the supply roller. Absent. The amount of toner originally held in the bubble of the supply roller 44 is relatively large, and a certain amount of residual toner remains in the recess of the developing roller. There are not many. Then, most of the toner is worn by the surface of the supply roller 44 that moves in the direction opposite to the surface of the development roller 42 at the outlet of the supply nip β while being filled in the recess of the development roller 42. Therefore, the toner can be supplied from the supply roller 44 to the developing roller 42 even when the electric field as described above is formed.

  In addition, since an alternating electric field is formed between the developing roller 42 and the supply roller 44, the toner generally reciprocates between the concave portion of the developing roller 42 and the air bubbles of the supply roller. . At this time, the residual toner remaining in the concave portion of the developing roller 42 before entering the supply nip β is mixed with new toner existing in the air bubbles of the supply roller 44. At this time, the toner having a large charge amount is preferentially transferred from the concave portion of the developing roller 42 to the empty bubbles of the supply roller 44 by the electric field described above. For this reason, in the supply nip β, the residual toner in the concave portion of the developing roller 42 is well collected in the empty bubbles of the supply toner 44.

  When the inventors actually conducted an experiment under the above-described bias conditions, the toner remaining in the recesses of the developing roller 42 was satisfactorily supplied from the supply roller 44 to the developing roller 42. Was successfully collected on the supply roller 44, and the occurrence of insufficient image density during continuous printing could be effectively suppressed.

[Second Embodiment]
FIG. 31 is a partially enlarged configuration diagram partially showing the developing device of the copying machine according to the second embodiment. In the copying machine according to the second embodiment, a dedicated collecting member for collecting the residual toner from the concave portion of the developing roller 42 is not provided. Instead, the inlet seal 47 is also used as a recovery member. A recovery bias is applied to the inlet seal 47 by a recovery bias power source 52.

  FIG. 32 is an enlarged configuration diagram showing the developing roller 42 and the inlet seal 47. The inlet seal 47 with the free end brought into contact with the peripheral surface of the developing roller 42 in a cantilevered state is formed on the surface of the sheet-like conductive portion 47b made of a conductive material and is in the form of a sheet made of an insulating material. This is a two-layer structure in which the insulating portion 47a is covered. As shown in the figure, only the insulating portion 47 a is in contact with the peripheral surface of the developing roller 42. As the conductive portion 47b, for example, an aluminum sheet having a thickness of about 50 [μm] can be exemplified. Moreover, as an insulating part, the PET (polyethylene terephthalate) sheet | seat of thickness 0.1 [mm] can be illustrated, for example. By bonding these two sheets together, an inlet seal 47 as shown in the figure can be formed. Instead of attaching the insulating sheet to the sheet-like conductive portion 47b, the surface of the conductive portion 47b may be coated with a film made of an insulating material such as urethane or fluorine.

  In FIG. 31, the developing bias output from the developing bias power supply 142 is applied to the developing roller 42 and is also input to the recovery bias power supply 52 although illustration of wiring is omitted. FIG. 33 is a graph showing the waveform of the developing bias applied to the developing roller 42 and the waveform of the recovery bias applied to the inlet seal 47. The developing bias is −300 [V] with respect to a rectangular alternating voltage having a peak-to-peak voltage of 1600 [V] that swings by 800 [V] around 0 [V]. The DC voltage superimposed is applied to the developing roller 42. As shown, the developing bias has a positive peak of 500 [V] and a negative peak of −1100 [V].

  The recovery bias power supply 52 outputs a superimposition of +200 [V] DC voltage on such a development bias as a recovery bias. As shown in the figure, the recovery bias has a peak-to-peak voltage of 1600 [V] which is the same as the development bias, but the positive peak is 700 [V] and the negative peak is -900 [V]. become. Since the period and phase are completely synchronized with the developing bias, the period and phase are always values shifted by 200 [V] to the positive side of the developing bias.

  In FIG. 32, an electric field that always electrostatically moves negatively charged toner from the developing roller 42 side to the inlet seal side 47 between the inlet seal 47 to which such a recovery bias is applied and the developing roller 42. Is formed. Since this electric field is also formed at the contact portion between the inlet seal 47 and the developing roller 42, the force pressing the toner against the surface of the developing roller 42 by the inlet seal 47 at the contact portion is the electrostatic force due to the electric field. It is weakened by. As a result, toner can be prevented from sticking to the surface of the developing roller 42 at the contact portion.

[Third embodiment]
The copying machine according to the third embodiment has the same configuration as the copying machine according to the second embodiment except for the points described below.
FIG. 34 is an enlarged configuration diagram showing the developing roller 42 and the entrance seal 47 of the copying machine according to the third embodiment. Of the conductive portion 47b and the insulating portion 47a, only the insulating portion 47a is directly cantilevered by the casing. The free end side of the insulating portion 47a that is cantilevered by the casing is in contact with the peripheral surface of the developing roller 42 as shown in the figure. The conductive portion 47b is located on the back surface of the region of the free end side of the insulating portion 47a that is shifted further to the free end side than the region in contact with the developing roller 42 and is not in contact with the developing roller 42. It is fixed. The conductive portion 47b is fixed so as to be cantilevered in the region. When a recovery bias is applied to the conductive portion 47b supported in this manner, a recovery electric field is formed between the surface of the developing roller 42 and the conductive portion 47b. This recovery electric field is developed between the insulating portion 47a and the developing portion. It does not reach the contact portion with the roller 42.

  FIG. 35 is a graph showing the waveform of the developing bias applied to the developing roller 42 of the copying machine according to the third embodiment and the waveform of the recovery bias applied to the conductive portion 47b of the inlet seal 47. The developing bias is −300 [V] with respect to a rectangular alternating voltage having a peak-to-peak voltage of 1600 [V] that swings by 800 [V] around 0 [V]. The DC voltage superimposed is applied to the developing roller 42. As shown, the developing bias has a positive peak of 500 [V] and a negative peak of −1100 [V]. On the other hand, as shown in the figure, a recovery bias having a DC voltage of −300 [V] is applied to the conductive portion 47b. As a result, an alternating electric field is formed between the conductive portion 47b and the surface of the developing roller 42 to move the toner back and forth between the two. By this alternating electric field, when the toner particles in the concave portion on the surface of the developing roller 42 reciprocate between the concave portion and the conductive portion 47b, the toner particles collide with the toner particles remaining in the concave portion, so that The reciprocating movement of the toner particles staying in the recess is promoted. Thereby, the recovery efficiency of the toner from the inside of the recess can be improved.

  The alternating electric field described above periodically applies a force from the conductive portion 47b side to the developing roller 42 side to the toner particles, but the alternating electric field is not formed between the insulating portion 47a and the developing roller 42. For this reason, it is possible to avoid occurrence of toner sticking to the roller surface by periodically applying an electrostatic force from the conductive portion 47b side to the developing roller 42 side to the toner particles by the collection electric field at the contact portion. Can do.

  Note that when the toner collection efficiency from the concave portion on the surface of the developing roller 42 is relatively low, the value of the collection bias may be shifted to the plus side (the side opposite to the toner charging polarity). For example, in the example of FIG. 35, the average potential of the developing bias per unit time is −300 [V]. If the recovery bias is shifted to a plus side from -300 [V], for example, -200 [V], the toner particles are moved back and forth by an alternating electric field, while relatively moving from the surface side of the developing roller 42. It can be moved to the conductive portion 47b side. Thereby, collection efficiency can be improved.

A recovery bias power source 52 is connected to the inlet seal 47, and a recovery bias composed of an alternating voltage is output from the recovery bias power source 52. This collection bias is the same as the collection bias of the copying machine according to the embodiment. The developing bias applied to the developing roller 42 is the same as the developing bias of the copying machine according to the embodiment. Therefore, an electric field for electrostatically moving the negatively charged toner from the developing roller 42 side to the inlet seal 47 side is formed at or near the contact portion between the developing roller 42 and the inlet seal 47. At the contact portion, the residual toner remaining in the concave portion of the developing roller 42 is attracted by the electric field and transferred to the surface of the inlet seal 47. Then, due to the rubbing force with the developing roller 42, the contact portion between the developing roller 42 and the entrance seal 47 is contacted.

  Next, a copying machine according to a modification in which a part of the configuration of the copying machine according to the embodiment is replaced with another configuration will be described. Unless otherwise specified below, the configuration of the copying machine according to each modification is the same as that of the embodiment.

[First Modification]
FIG. 23 is a main part configuration diagram showing the main part of the printer unit 600 of the copying machine according to the first modification. The printer unit 600 includes a process cartridge 1 as four process units, an intermediate transfer belt 7 as an intermediate transfer body that is endlessly moved in a counterclockwise direction while being stretched by a plurality of stretching rollers, and an exposure unit. An exposure device 6 and a fixing device 12 as fixing means are provided.

  Each of the four process cartridges 1 develops a latent image on the photoreceptor 2 using a drum-shaped photoreceptor 2 as a latent image carrier, a charging member 3 as a charging unit, and toner T as a developer. The developing device 4 and the photosensitive member cleaning device 5 are integrally supported to form a unit shape. The process cartridge 1 can be attached to and detached from the printer unit 600 main body by releasing a stopper (not shown).

  The photoconductor 2 rotates in the clockwise direction in the figure as indicated by an arrow in the figure. The charging member 3 is a roller-shaped charging roller, is in pressure contact with the surface of the photoconductor 2, and is rotated by the rotation of the photoconductor 2. At the time of image formation, a predetermined bias is applied to the charging member 3 by a high voltage power source (not shown) to charge the surface of the photoreceptor 2. The process cartridge 1 of the modification uses a roller-shaped charging member 3 that contacts the surface of the photoreceptor 2 as the charging means, but the charging means is not limited to this, and non-contact charging such as corona charging. A method may be used.

  The exposure device 6 exposes the surface of the photoreceptor 2 based on image information, and forms an electrostatic latent image on the surface of the photoreceptor 2. The exposure device 6 of the printer 600 is of a laser beam scanner type using a laser diode, but may have other configurations such as an exposure unit using an LED array.

  The photoconductor cleaning device 5 cleans the transfer residual toner remaining on the surface of the photoconductor 2 that has passed the position facing the intermediate transfer belt 7.

  The four process cartridges 1 form toner images for the respective colors of yellow, cyan, magenta, and black on the photoreceptor 2. In addition, the toner images formed on the respective photoreceptors 2 are arranged in parallel with the surface movement direction of the intermediate transfer belt 7 and transferred onto the intermediate transfer belt 7 in order to be superimposed on each other. Form a visual image.

  A primary transfer roller 8 serving as a primary transfer unit is disposed at a position facing the four photoconductors 2 with the intermediate transfer belt 7 interposed therebetween. A primary transfer bias is applied to the primary transfer roller 8 by a high voltage power source (not shown). Is applied to form a primary transfer electric field with the photosensitive member 2. By forming a primary transfer electric field between the photosensitive member 2 and the primary transfer roller 8, the toner image formed on the surface of the photosensitive member 2 is transferred to the surface of the intermediate transfer belt 7. One of a plurality of stretching rollers that stretch the intermediate transfer belt 7 is rotated by a drive motor (not shown), so that the intermediate transfer belt 7 moves in the direction of arrow A in the figure. A full color image is formed on the surface of the intermediate transfer belt 7 by sequentially transferring the toner images of the respective colors on the surface of the intermediate transfer belt 7 moving on the surface.

  With respect to the position where the four process cartridges 1 are opposed to the intermediate transfer belt 7, the intermediate transfer belt 7 is located on the downstream side of the surface movement direction with respect to the secondary transfer counter roller 9a which is one of the stretching rollers. A secondary transfer roller 9 is disposed at a position opposed to the belt 7 and forms a secondary transfer nip with the intermediate transfer belt 7. Recording paper which is a transfer material conveyed in the direction of arrow B in FIG. 23 by applying a predetermined voltage between the secondary transfer roller 9 and the secondary transfer counter roller 9a to form a secondary transfer electric field. When P passes through the secondary transfer nip, the full color image formed on the surface of the intermediate transfer belt 7 is transferred onto the recording paper P.

  A fixing device 12 is disposed downstream of the secondary transfer nip in the conveyance direction of the recording paper P. The recording paper P that has passed through the secondary transfer nip reaches the fixing device 12, the full color image transferred onto the recording paper P is fixed by heating and pressurization in the fixing device 12, and the recording paper P on which the image is fixed is The data is output outside the printer unit 600.

  On the other hand, the toner T remaining on the surface of the intermediate transfer belt 7 without being transferred to the recording paper P at the secondary transfer nip is collected by the transfer belt cleaning device 11.

  Next, the process cartridge 1 will be described with reference to FIGS. 24, 25, and 26. FIG. 24 is a transverse cross-sectional view showing one of the four process cartridges 1 in the vicinity of the central portion of the developing roller 42 in the axial direction. FIG. 25 is a cross-sectional view showing one of the four process cartridges 1 at a position of the side seal 59 near the end in the axial direction. FIG. 26 is a longitudinal sectional view showing a toner conveying portion of the developing device of the process cartridge.

  The developing device 4 includes a toner storage chamber 101 that stores toner T that is a one-component developer, and a toner supply chamber 102 that is provided below the toner storage chamber 101. A partition member 110 is provided so as to partition the chamber 102. As shown in FIG. 26, the partition member 110 is provided with a plurality of openings that allow the supply chambers to communicate with each other. As a plurality of openings of the partition member 110, a supply port 111 that supplies the toner T in the toner storage chamber 101 to the toner supply chamber 102 and a return port 107 that returns the toner T in the toner supply chamber 102 to the toner storage chamber 101. And are provided.

  Below the toner supply chamber 102, a developing roller 42 as a developer carrier is provided. In the toner supply chamber 102, a supply roller 44, which is a developer supply member that supplies toner T to the surface of the developing roller 42, is provided in contact with the surface of the developing roller 42. Further, the toner supply chamber 102 is a regulating member that regulates the amount (layer thickness) of the toner T that is supplied onto the surface of the developing roller 42 by the supply roller 44 and moves toward the opposing portion of the photoreceptor 2 and the developing roller 42. The doctor blade 45 is in contact with the surface of the developing roller 42.

  The developing roller 42 is disposed in a non-contact manner with respect to the photoreceptor 2 and is applied with a predetermined bias from a high voltage power source (not shown).

  A toner conveying member 106 that conveys the toner T in the toner accommodating chamber 101 in a direction parallel to the rotation axis of the photosensitive member 2 (a direction orthogonal to the paper surface in FIG. 24) is provided in the toner accommodating chamber 101.

  The toner T stored in the toner storage chamber 101 is manufactured by a polymerization method. This toner T is, for example, a toner T having an average particle diameter of 6.5 [μm], a circularity of 0.98, an angle of repose of 33 [°], and strontium titanate as an external additive. . The toner T is not limited to this.

  As shown in FIG. 26, the toner conveyance member 106 provided in the toner storage chamber 101 is a member having a rotation shaft that combines a conveyance screw shape portion 106a and a conveyance plate shape portion 106b. The toner conveying member 106 is configured to convey the toner T in the toner storage chamber 101 in a substantially horizontal direction (in the direction of arrow H in FIG. 26) parallel to the rotation axis of the toner conveying member 106 by the rotation operation of the conveying screw-shaped portion 106a. It has become. The developing device 4 includes a conveyance screw shape portion 106a that conveys the toner T in a direction parallel to the rotation axis of the toner conveyance member 106. However, the developer conveyance member is not limited to this, and the conveyance device is not limited thereto. What has conveyance functions, such as a belt and a coiled rotating body, can be used. Furthermore, what has these conveyance functions and what has a loosening function, such as a paddle formed by bending a plate member such as a blade or a wire, may be combined.

  The developing device 4 is configured to convey the toner T from the toner storage chamber 101 toward the supply roller 44 in a direction perpendicular to the rotation axis of the toner conveying member 106 and substantially vertically downward. The toner T may be transported in a substantially horizontal direction perpendicular to the rotation axis of the toner transport member 106 as the transport direction of the toner T.

  A toner stirring member 108 is disposed in the toner supply chamber 102 vertically below the partition member 110. As shown in the figure, the toner stirring member 108 is a member having a rotating shaft in which a stirring screw shape portion 108a and a stirring plate shape portion 108b are combined. The toner agitating member 108 conveys the toner T in the toner supply chamber 102 in a substantially horizontal direction (in the direction of arrow I or J in FIG. 26) parallel to the rotation axis of the toner agitating member 108 by the rotation operation of the agitating screw-shaped portion 108a. It can be configured.

  The agitating screw-shaped portion 108a of the toner agitating member 108 is provided with a spiral wing portion so as to convey the toner T in the direction toward the outside (in the direction of arrow I in FIG. 26) across the supply port 111 in the axial direction. ing. Further, the agitating screw-shaped portion 108a of the toner agitating member 108 is spirally wound with a spiral wing on the outside and inside of the two return ports 107 in the axial direction. For this reason, the toner T supplied from the supply port 111 to the toner supply chamber 102 is conveyed outward in the axial direction (in the direction of arrow I) by the rotation of the stirring screw-shaped portion 108 a of the toner stirring member 108, and outside the return port 107. The reached toner T is conveyed toward the return port 107 (in the direction of arrow J) by the stirring screw-shaped portion 108a whose wing portion is wound in reverse. The conveying direction of the toner T by the stirring screw-shaped portion 108 a is opposite between the outside and the inside in the axial direction across the return port 107, and a transfer force is applied to the toner T toward the return port 107. Below 107, the toner T is collected from both sides in the axial direction and pushed up in a mountain shape. As a result, when the amount of toner T supplied from the toner storage chamber 101 through the supply port 111 or the return port 107 to the toner supply chamber 102 is excessive, the toner T pushed up in the mountain shape by the return port 107 becomes the toner. The toner is returned from the supply chamber 102 to the toner storage chamber 101 through the return port 107. The toner agitating member 108 has a role of agitating the toner T in the toner supply chamber 102 and further supplying the toner T to the supply roller 44 and the developing roller 42 below.

The surface of the supply roller 44 is covered with a foam material having a structure having pores (cells), and the toner T supplied to the toner supply chamber 102 is efficiently attached and taken in, and the surface of the supply roller 44 is connected to the developing roller 42. Deterioration of the toner T due to pressure concentration at the contact portion is prevented. In addition, this foaming material is set to an electrical resistance value of 10 ³ to 10 ¹⁴ [Ω]. A supply bias is applied to the supply roller 44 and assists the operation of pressing the toner T preliminarily charged at the supply nip β in contact with the development roller 42 against the development roller 42. The supply roller 44 rotates in the counterclockwise direction in FIG. 37 as indicated by an arrow in FIG. 37 and supplies the toner T adhered to the surface so as to be applied to the surface of the developing roller 42.

  A doctor blade 45 as a regulating member is disposed so as to come into contact with the surface of the developing roller 42 on the downstream side in the surface movement direction of the developing roller 42 with respect to the supply nip β. The toner T supplied from the supply roller 44 to the surface of the developing roller 42 is conveyed to a position where the doctor blade 45 contacts with the rotation of the developing roller 42.

  As the doctor blade 45, a metal leaf spring material such as SUS304CSP, SUS301CSP, or phosphor bronze can be used, and its free end is brought into contact with the surface of the developing roller 42 with a pressing force of 10 to 100 [N / m]. In addition, by passing the toner T on the developing roller 42 under the pressing force, the toner layer is thinned and a charge is applied to the toner T by frictional charging. In addition, a bias is applied to the doctor blade 45 by a bias power source (not shown) in order to assist the frictional charging of the toner T.

  The photoreceptor 2 is not in contact with the developing roller 42 and rotates in the clockwise direction in FIG. Therefore, at the development position α where the developing roller 42 and the photoconductor 2 face each other, the surface moving direction of the developing roller 42 and the surface moving direction of the photoconductor 2 are the same direction.

  The thinned toner layer on the developing roller 42 is conveyed to the developing position α as the developing roller 42 rotates, and is formed by a bias applied to the developing roller 42 and an electrostatic latent image on the photoreceptor 2. The electrostatic latent image on the surface of the photoreceptor 2 is developed by moving to the surface of the photoreceptor 2 in accordance with the latent image electric field.

  An entrance seal 47 is disposed at a location where the toner T that is not used for development at the development position α and remains on the development roller 42 returns to the toner supply chamber 102 again. The inlet seal 47 is cantilevered by a developing device housing having an opening for partially exposing the peripheral surface of the developing roller 42 to the outside, and the free end side of the inlet seal 47 contacts the developing roller 42. By contacting, the gap between the developing roller 42 and the inner wall of the opening is closed. It is made of a conductive resin in which a conductive material such as carbon black is dispersed in a resin material, and can be flexibly flexed by being molded in a very thin thickness. Because of the ease of bending, a large pressure is not applied to the surface of the developing roller 42 at the contact portion with the surface of the developing roller 42.

  Of the entire area of the peripheral surface of the developing roller 42, the collection brush roller 51 is in contact with the region before passing the developing position α and before entering the contact position with the supply roller 44. It is rotating in the direction. The collection brush roller 51 is formed by forming a brush portion made of a plurality of conductive brushes on the peripheral surface of a metal shaft member.

  The conductive raising of the brush portion of the collection brush roller 51 causes its tip portion to enter the recess of the developing roller 42 as it rotates, and scrapes the residual toner remaining in the recess from the recess. As shown in the drawing, at the contact portion between the developing roller 42 and the collection brush roller 51, the surfaces of the two move in the counter direction, so that the conductive brushing of the collection brush roller 51 causes more than the movement in the forward direction. The effect of scraping residual toner from the inside of the recess can be enhanced.

  A developing bias power source 142 that outputs a developing bias to be applied to the developing roller 42 outputs a developing bias having an alternating voltage similar to the developing bias of the copying machine according to the embodiment. A recovery bias power source 52 that outputs a recovery bias to be applied to the recovery brush roller 51 outputs a recovery bias having an alternating voltage similar to the recovery bias of the copier according to the embodiment. Therefore, a collecting electric field that electrostatically moves toner from the developing roller 42 side to the collecting brush roller 51 side is formed at the contact portion between the developing roller 42 and the collecting brush roller 51.

  At the contact portion between the developing roller 42 and the collecting brush roller 51, the residual toner remaining in the recess of the developing roller 42 is scraped out from the recess by the conductive brushing of the collecting brush roller 51, and then recovered. Is transferred into the brush of the recovery brush roller 51 and recovered.

[Second Modification]
The copying machine according to the second modification has the same configuration as that of the copying machine according to the first modification, except for the following points.
FIG. 27 is a schematic configuration diagram showing a photoconductor and a developing device of a copying machine according to a second modification. In the copying machine according to the second modified example, a dedicated collecting member for collecting the residual toner from the concave portion of the developing roller 42 is not provided. Instead, a supply roller 44 composed of a foam roller having a metal core and a conductive elastic foam layer coated on the peripheral surface thereof is also used as a recovery foam roller as a recovery member. As a power source for outputting a bias to be applied to the supply roller 44, a recovery bias power source 52 is provided instead of the supply bias power source.

  A developing bias power source 142 that outputs a developing bias to be applied to the developing roller 42 outputs a developing bias having an alternating voltage similar to the developing bias of the copying machine according to the embodiment. A recovery bias power supply 52 that outputs a recovery bias to be applied to the recovery brush roller 51 outputs a recovery bias having an alternating voltage similar to the recovery bias of the copying machine according to the embodiment.

  As a result of actual experiments under these bias conditions, the present inventors have successfully supplied a necessary amount of toner from the supply roller 44 to the developing roller 42 as in the copying machine according to the embodiment. Further, the residual toner in the concave portion of the developing roller 42 was recovered to the supply roller 44, and the occurrence of insufficient image density during continuous printing could be effectively suppressed.

[Third Modification]
The copying machine according to the third modified example has the same configuration as the copying machine according to the first modified example, except for the following points.
FIG. 28 is a schematic configuration diagram showing a photoconductor and a developing device of a copying machine according to a third modification. In the copying machine according to the third modified example, a dedicated collecting member for collecting the residual toner from the concave portion of the developing roller 42 is not provided. Instead, the inlet seal 47 is also used as a recovery member.

  A recovery bias power source 52 is connected to the inlet seal 47, and a recovery bias composed of an alternating voltage is output from the recovery bias power source 52. This collection bias is the same as the collection bias of the copying machine according to the embodiment. The developing bias applied to the developing roller 42 is the same as the developing bias of the copying machine according to the embodiment. Therefore, an electric field for electrostatically moving the negatively charged toner from the developing roller 42 side to the inlet seal 47 side is formed at or near the contact portion between the developing roller 42 and the inlet seal 47. At the contact portion, the residual toner remaining in the concave portion of the developing roller 42 is attracted by the electric field and transferred to the surface of the inlet seal 47. Then, by the rubbing force with the developing roller 42, the developing roller 42 moves from the contact portion between the developing roller 42 and the inlet seal 47 to the contact portion outlet side, and is taken into the toner in the toner supply chamber 102.

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]
Aspect A includes a developer carrying member (for example, developing roller 42) that carries a developer containing toner as a main component and not containing a magnetic carrier on its surface on which a predetermined recessed portion (for example, recessed portion 42b) pattern is formed; A developer supply means (for example, a supply roller 44) for supplying a developer to the surface of the developer carrier, and a supply position facing the developer supply means in the entire area of the endlessly moving surface of the developer carrier. A regulating member (for example, a doctor blade) that regulates the amount of developer conveyed to the developing position by contacting the area before entering the developing position facing the latent image carrier of the image forming apparatus after passing through 45) and a developing bias output means (for example, a developing bias power source 142) for outputting a developing bias to be applied to the developer carrying member, and at the developing position, the developer In a developing device for developing a latent image by attaching a developer held in a recess of the recess pattern of a holder to a latent image on the surface of the latent image carrier, the entire area of the surface of the developer carrier is Among them, a recovery member (for example, transferring the developer attached to the region to itself and recovering it while contacting the region before entering the regulation position that contacts the regulation member after passing through the development position (for example, The recovery brush roller 51) is applied to the recovery member to form an electric field for moving the developer relatively from the developer carrier side to the recovery member side between the developer carrier and the recovery member. And a recovery bias output means (for example, a recovery bias power supply 52).

[Aspect B]
Aspect B is a recovery brush roller (for example, recovery brush roller 51) provided with a plurality of raised brushes on the surface of a conductive substrate that is rotationally driven as the recovery member in aspect A, or on the surface of the rotating shaft. A recovery foam roller coated with a foam elastic layer is used. In this configuration, the raised brush of the collection brush roller or the foamed elastic layer of the collection foam roller is caused to enter the recess of the developer carrier while being flexibly deformed at the contact portion with the developer carrier. Then, the developer remaining in the concave portion is scraped out from the concave portion satisfactorily by the raised or foamed elastic layer, so that the toner from the concave portion can be removed as compared with the case of using another configuration as the recovery member. It can be recovered well.

[Aspect C]
Aspect C is that in aspect B, the developer supply means is a supply brush roller provided with a plurality of raised brushes on the surface of a conductive substrate that is driven to rotate, or a surface of the rotary shaft is covered with a foamed elastic layer The supply foam roller (for example, supply roller 44) is used, and the development bias is output with an alternating voltage having a center value of a value shifted from zero to the same polarity as the charging polarity of the toner. The developing bias output means is configured, and the recovery bias is a value shifted to the same polarity side as the charging polarity of the toner from zero, and is opposite in polarity to the charging polarity from the central value of the developing bias The recovery bias output means is configured to output a voltage consisting of an alternating voltage centered on a value shifted to the side, and the recovery bias is supplied to the supply brush roller It is applied to the supply foam roller, or also serves the supply brush roller as the collection brush roller, or, is characterized in that also serves the supply foam roller as said recovery foam roller. In such a configuration, the developer can be recovered well from the developer carrying member by the supply brush roller or the supply foaming roller without providing a dedicated collecting member for collecting the residual toner from the developer carrying member. New toner can be satisfactorily supplied to the carrier.

[Aspect D]
Aspect D is that in Aspect A, the free end side of the developer carrying member is supported by the developing device housing having an opening for partially exposing the peripheral surface of the developer carrying member to the outside. The recovery bias is applied to a seal member (for example, the inlet seal 47) that closes the gap between the developer carrier and the inner wall of the opening by contacting the carrier, and the seal member is also used as the recovery member. It is characterized by this. In such a configuration, without providing a dedicated recovery member for recovering the residual toner from the developer carrier, the residual toner is satisfactorily recovered from the developer carrier by the seal member. New toner can be supplied satisfactorily.

[Aspect E]
Aspect E constitutes the developing bias output means according to aspect D so as to output the developing bias having an alternating voltage centered on a value shifted from zero to the same polarity as the charging polarity of the toner. As the recovery bias, a value shifted from zero to the same polarity as the charging polarity of the toner and a value shifted from the central value of the developing bias to the polarity opposite to the charging polarity is centered. The recovery bias output means is configured to output a voltage consisting of an alternating voltage as a value. With this configuration, the toner on the surface of the developer carrying member can be recovered by being transferred to the seal member by electrostatic force.

[Aspect F]
Aspect F uses, in aspect D, a seal member having a conductive portion made of a conductive material to which the recovery bias is applied and an insulating portion made of an insulating material, and the conductive portion and the insulating portion Among them, only the insulating portion is brought into contact with the peripheral surface of the developer carrier. In such a configuration, it is possible to avoid the occurrence of current leakage between the inlet seal and the developer carrier due to the conductive portion of the inlet seal being brought into contact with the developer carrier.

[Aspect G]
Aspect G is the aspect F in which the surface of the conductive portion is covered with the insulating portion, and toner is always applied between the developer carrying member to which the developing bias is applied and the conductive portion. The recovery bias output means is configured to output, as the recovery bias, a DC voltage having a value that forms an electric field in a direction to move from the carrier side toward the conductive portion side. It is characterized by this. In such a configuration, the force that presses the toner against the surface of the developer carrier by the seal member at the contact portion between the seal member and the developer carrier, and the electric field formed between the conductive portion of the seal member and the developer carrier. It is weakened by electrostatic force. Thereby, it is possible to suppress the occurrence of toner adhesion to the surface of the developer carrying member at the contact portion.

[Aspect H]
Aspect H is a free end of the insulating portion that is cantilever-supported in aspect F, and the conductive portion with respect to a region closer to the free end than a region that contacts the peripheral surface of the developer carrier. The recovery bias is a DC voltage having a value that forms an alternating electric field for reciprocating the toner between the developer carrying member to which the developing bias is applied and the conductive portion. Thus, the recovery bias output means is configured. In such a configuration, the toner is reciprocated between the conductive portion and the developer carrying member, thereby promoting the separation of the toner particles from the recesses on the surface of the developer carrying member, thereby increasing the toner recovery efficiency. Can do. In addition, the occurrence of toner sticking to the surface of the developer carrier caused by periodically applying an electrostatic force from the conductive part side to the developer carrier side to the toner particles by the collected electric field at the contact portion is avoided. can do.

1: Process cartridge (process unit)
2: Photoconductor (latent image carrier)
3: Charging member (uniform charging means)
4: Developing device 5: Photoconductor cleaning device (cleaning means)
42: Development roller (developer carrier)
44: Supply roller (developer supply means, supply brush roller)
45: Doctor blade (regulating member)
47: Entrance seal (seal member)
51: Collection brush roller (collection member)
52: Recovery bias power supply (recovery bias output means)
142: Development bias power supply (development bias output means)

JP 2007-178901 A JP 2007-121951 A

Claims (10)

A developer carrier that carries toner on its surface on which a predetermined concave pattern is formed;
Developer supplying means for supplying toner to the surface of the developer carrying member;
Of the entire area of the surface of the developer carrying member that moves endlessly, the region before passing the feeding position facing the developer feeding means and before entering the developing position facing the latent image carrier of the image forming apparatus. A regulating member that regulates the amount of toner conveyed to the developing position by abutting;
In a developing device having a developing bias output means for outputting a developing bias for applying to the developer carrying member,
Of the entire area on the surface of the developer carrying member, the toner adhering to the region is contacted with itself while passing through the developing position and before entering the restricting position contacting the restricting member. A collecting member for transferring and collecting;
A collection bias output means for outputting a collection bias to be applied to the collection member in order to form an electric field for moving toner from the developer carrier side to the collection member side between the developer carrier and the collection member; And a developing device. The developing device according to claim 1.
As the recovery member, a recovery brush roller provided with a plurality of raised brushes on the surface of a conductive substrate that is driven to rotate, or a recovery foam roller in which the surface of the rotary shaft is covered with a foam elastic layer is used. A developing device. The developing device according to claim 2.
As the developer supply means, a supply brush roller provided with a plurality of raised brushes on the surface of a conductive substrate that is driven to rotate, or a supply foam roller in which a foamed elastic layer is coated on the surface of a rotary shaft is used. ,
The developing bias output means is configured to output an alternating voltage having a center value of a value shifted from zero to the same polarity as the charging polarity of the toner from zero,
The recovery bias is a value shifted to the same polarity as the charging polarity of the toner from zero, and a value shifted to the polarity opposite to the charging polarity from the central value of the developing bias is defined as the central value. The recovery bias output means is configured to output a voltage consisting of an alternating voltage.
The recovery bias is applied to the supply brush roller or the supply foam roller, and the supply brush roller is also used as the recovery brush roller, or the supply foam roller is also used as the recovery foam roller. Developing device. The developing device according to claim 1.
By bringing the free end side of the developer carrier into contact with the developer carrier while being cantilevered by a developing device housing having an opening for partially exposing the peripheral surface of the developer carrier to the outside. A developing device, wherein the recovery bias is applied to a seal member that closes a gap between the developer carrying member and the inner wall of the opening, and the seal member is also used as the recovery member. The developing device according to claim 4.
The developing bias output means is configured to output an alternating voltage having a center value of a value shifted from zero to the same polarity as the charging polarity of the toner from zero,
The recovery bias is a value shifted to the same polarity as the charging polarity of the toner from zero, and a value shifted to the polarity opposite to the charging polarity from the central value of the developing bias is defined as the central value. A developing device characterized in that the recovery bias output means is configured to output a voltage composed of alternating voltage. The developing device according to claim 4.
As the sealing member, a member having a conductive part made of a conductive material to which the recovery bias is applied and an insulating part made of an insulating material is used, and only the insulating part is selected from the conductive part and the insulating part. A developing device, wherein the developing device is brought into contact with a peripheral surface of the developer carrying member. The developing device according to claim 6.
While covering the surface of the conductive portion with the insulating portion,
A DC voltage having a value that forms an electric field between the developer carrying member to which the developing bias is applied and the conductive unit in a direction in which the toner is always moved from the developer carrying unit toward the conductive unit. A developing device characterized in that the recovery bias output means is configured to output a voltage applied to the developing bias as the recovery bias. The developing device according to claim 6.
Fixing the conductive part to a free end of the insulating part that is cantilevered and to a region on the free end side of a region contacting the peripheral surface of the developer carrier;
The recovery bias is output so as to output a DC voltage having a value that forms an alternating electric field that reciprocally moves toner between the developer carrying member to which the developing bias is applied and the conductive portion. A developing device comprising a recovery bias output means. A latent image carrier for carrying a latent image; uniform charging means for uniformly charging the surface of the latent image carrier; a developing device for developing the latent image carried on the surface of the latent image carrier; Transfer means for transferring the toner image developed on the surface of the latent image carrier to a transfer body, and a transfer residue adhering to the surface of the latent image carrier after passing through a position facing the transfer means. The image forming apparatus includes a cleaning unit that cleans toner, and holds the developing device and at least one of the latent image carrier, the uniform charging unit, and the cleaning unit with a common holding unit. In the process unit that is integrally attached to and detached from the image forming apparatus main body in the
A process unit using the developing device according to claim 1 as the developing device. A latent image carrier for carrying a latent image; uniform charging means for uniformly charging the surface of the latent image carrier; a developing device for developing the latent image carried on the surface of the latent image carrier; Transfer means for transferring the toner image developed on the surface of the latent image carrier to a transfer body, and a transfer residue adhering to the surface of the latent image carrier after passing through a position facing the transfer means. In an image forming apparatus comprising a cleaning means for cleaning toner,
An image forming apparatus using the developing device according to claim 1 as the developing device.

Images