JP2011102850A - Developing sleeve, developer carrier, developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein troubles where inferior image quality occurs in an image forming apparatus, when a developer carrier is assembled with a developing sleeve, having a directionality in the rotating direction, with the sleeve rotating in the reverse direction. <P>SOLUTION: In the developing sleeve having directionality in the rotating direction and having a surface-prepared part that has been subjected to surface treatment for conveying a developer composed of a toner and a carrier, and surface-prepared parts that have not been subjected to the surface treatment, and are provided on both sides of the surface-prepared part, recessed grooves that set continuous in the circumferential direction, being formed on one of the surface-prepared parts. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a laser printer or a digital copying machine, and a developing device, a developer carrier, and a developing sleeve used in the image forming apparatus.

  As a developing device used in an image forming apparatus such as a printer or a copying machine, for example, a developer agitating member is disposed on the developer carrying member that is disposed opposite to the photosensitive member and is driven to rotate. A two-component developer composed of toner and a magnetic carrier (hereinafter referred to as “developer”) is held (adsorbed), transported to a development area facing the photoreceptor, and formed on the surface of the photoreceptor by toner transfer. A device that develops the electrostatic latent image is known (see, for example, Patent Document 1).

  This developer carrier is provided at both ends of a magnet roll having a predetermined magnetic field waveform formed by arranging permanent magnets having a plurality of magnetic poles in the circumferential direction of the shaft, and the shaft of the magnet roll. The main component is a developing sleeve of a non-magnetic cylindrical body that is rotatably supported via a bearing.

  The developing sleeve has a function of transporting the developer adsorbed on the surface by the magnetic attractive force of the magnet roll inside. In order to improve the developer conveying force, a developing sleeve having a groove forming portion having a groove formed on the surface and a developing sleeve having a surface treatment portion subjected to surface treatment such as blasting on the surface have been proposed. (For example, refer to Patent Documents 2 to 6).

Japanese Patent Laying-Open No. 2005-077494 JP 2000-321864 A Japanese Patent Laid-Open No. 08-227219 (FIG. 9 etc.) JP-A-60-186458 (FIGS. 3, 4, etc.) Japanese Patent Publication No. 36-014871 (Fig. 3 etc.) JP 2004-021122 A

  In the conventional developing sleeve described above, there is a problem that, depending on the specifications of the developing sleeve, when the developer carrying member is mistakenly assembled, a defect such as an image quality defect occurs in the image forming apparatus. This problem will be described below.

  For example, if the developing sleeve described in Patent Documents 2 to 5 has directionality in the rotation direction, the developing sleeve is reversed (attached to rotate in the direction opposite to the original rotation direction, and the developer is carried. When the body is assembled), the amount of developer transport differs from the design value, and there is a problem that an image quality defect occurs in the image forming apparatus.

  In addition, for example, as in Patent Document 6, a development including a non-groove forming portion in which no groove is formed or a non-surface treated portion in which surface treatment is not performed on both sides of the groove forming portion and the surface processing portion described above. In the sleeve, when one non-grooved portion is longer than the other non-grooved portion, or when one non-surface treated portion is longer than the other non-surface-treated portion, the developer is removed by reversing the developing sleeve. Unlike the design value, the transport position is different from the design value, and there is a problem that an image quality defect occurs in the image forming apparatus.

  In order to solve these problems, it is possible to adopt a means for attaching a mark to the non-grooved portion or the non-surface treatment portion of the developing sleeve with oil-based ink or the like so that the direction can be visually recognized and to prevent reverse attachment. .

  However, in this case, it is necessary to provide a separate process for marking the developing sleeve, resulting in an increase in the manufacturing process and manufacturing tact of the developing sleeve, and consequently the cost of the developer carrier, the developing device, and the image forming apparatus. There is a problem that is up. Further, depending on how the mark or the like is attached, there is a possibility that the developer adheres to the mark or the like or the mark or the like conveys the developer and induces an image quality defect of the image forming apparatus.

  The present invention has been made in order to solve the above-described problems, and is inexpensive because of a simple configuration in which concave grooves continuous in the circumferential direction are provided in the non-groove forming portion or the non-surface treatment portion of the developing sleeve. An object of the present invention is to provide a developing sleeve, a developer carrying member, a developing device, and an image forming apparatus that can prevent reverse attachment and that do not induce image quality defects (image quality defects) of the image forming apparatus even if a concave groove is provided.

(First invention)
A first aspect of the present invention is a surface treatment unit that has been subjected to a surface treatment for transporting a developer composed of toner and a carrier, and a non-surface treatment unit that is provided on both sides of the surface treatment unit and that has not been subjected to a surface treatment. A developing sleeve having directionality in the rotational direction is characterized in that a concave groove continuous in the circumferential direction is formed in one non-surface treatment portion.

  With this configuration, when the developer carrying member is assembled using the developing sleeve, the directionality can be easily visually recognized by the concave groove, and therefore, the reverse mounting of the developing sleeve can be prevented. Further, since the groove is formed continuously in the circumferential direction, even if the developer enters the groove, the developer does not remain in the groove, so that the non-surface-treated portion removes the developer. There is no conveyance in the rotation direction and / or the axial direction (longitudinal direction). For this reason, it is possible to prevent image quality defects and the like of the image forming apparatus due to the non-surface treatment unit conveying the developer.

(Second invention)
The developing sleeve of the second invention is the developing sleeve according to the first invention, wherein the width of the groove is made larger than the diameter of the carrier. With this configuration, since the carrier that has entered the groove is less likely to be clogged, the developer does not remain even if the developer enters the groove, so that the non-surface-treated portion removes the developer. There is no conveyance in the rotation direction and / or the axial direction (longitudinal direction). For this reason, it is possible to prevent image quality defects and the like of the image forming apparatus due to the non-surface treatment unit conveying the developer.

(Third invention)
A third invention relates to a developer carrying member including the developing sleeve of the first invention or the second invention and a magnet roll inserted into the developing sleeve.
Since the developer carrying member according to the third invention uses the developing sleeve that exhibits the above-described effects, it is possible to provide a developer carrying member that prevents the occurrence of image quality defects of the image forming apparatus based on the reverse mounting of the developing sleeve. .

(Fourth invention)
According to a fourth aspect of the present invention, the developer carrying member of the third invention, a layer thickness regulating member (blade) provided opposite to the developer carrying member, and a developer stirring member for stirring the developer are provided in the housing. The present invention relates to a developing device provided.
Since the developing device according to the fourth aspect of the invention uses the developer carrying member that exhibits the above-described effects, it is possible to provide a developing device that prevents the occurrence of image quality defects of the image forming apparatus based on the reverse mounting of the developing sleeve.

(Fifth invention)
A fifth invention relates to an image forming apparatus comprising the developing device of the fourth invention and a photosensitive member facing the developer carrying member of the developing device.
Since the image forming apparatus according to the fifth aspect uses the developing device that exhibits the above-described effects, it is possible to provide an image forming device that prevents the occurrence of image quality problems due to reverse mounting of the developing sleeve.

  The present invention can provide a developing sleeve, a developer carrying member, a developing device, and an image forming apparatus that are inexpensive and can be prevented from being turned over, and that do not induce poor image quality even when a concave groove is provided.

Schematic structure diagram of magnet roll (Example 1) Side view of the magnet roll of FIG. 1 (Example 1) Front view of developer carrier (Example 1) Sectional diagram of developer carrier (Example 1) Partial enlarged view of the developing sleeve near the groove (Example 1) Sectional view of developing device (Example 1) FIG. 6 is a partially enlarged view of the developing device (Example 1). Sectional view of magnet piece mold (Example 1) Front view of developer carrier (Example 2) FIG. 7 is a diagram for explaining the configuration of an image forming apparatus (third embodiment).

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not intended to be interpreted as being limited to the developer carrier shown in FIGS. 3 and 4 and the developing device shown in FIGS.

(Developer)
As shown in FIG. 6, the developing device 61 according to the present invention holds an electrostatic latent image formed on the surface of a photoreceptor roll 71 as a photoreceptor on the surface of the developing sleeve 34 of the developer carrier 31 ( It is of the type that develops using the adsorbed developer. The developing device 61 supplies a developer carrier 31 provided close to and opposite to the photoconductor roll 71 and a developer composed of toner and a magnetic carrier to the developer carrier 31 while stirring. The developer agitating members 63 and 64 and the layer thickness regulating member 67 for regulating the layer thickness of the developer held on the surface of the developing sleeve 34 are provided inside the housing 62.

  Further, as shown in FIG. 6, the developer agitating members 63 and 64 are provided such that the axial direction (longitudinal direction) thereof is substantially parallel to the axial direction (longitudinal direction) of the developer carrier 31. The developer is conveyed by being driven to rotate in opposite directions. Since the first stirring chamber 65 communicates with the second stirring chamber 66 at both ends in the axial direction of the developer carrier 31, the developer is stirred while circulating in the housing 62.

  Further, the developer is agitated while circulating in the housing 62, whereby a sufficient charge is imparted to the toner, and the charge is measured by a toner density sensor (not shown). When the toner concentration is lowered, the low toner concentration developer is adjusted to a predetermined toner concentration (becomes an appropriate toner concentration developer) by supplying toner from a toner hopper (not shown).

(Development process)
Hereinafter, a series of development processes after the developer having an appropriate toner concentration adjusted to a predetermined toner concentration is adsorbed on the surface of the developer carrier 31 will be described.
FIG. 7 shows the movement of the developer in the enlarged view of the vicinity of the developer carrier 31 in the developing device 61 shown in FIG. Although the developer is represented by a circle in FIG. 7, since the development process is schematically described, the toner constituting the developer and the magnetic carrier are not distinguished. Further, there are two types of circles representing the developer (“◯” and “●”), the appropriate toner concentration developer 68 is a black circle (“●”), and the low toner concentration developer 69 is a white circle (“◯”). ]). In addition, the surface of the developing sleeve 34 in FIG. 7 shows a state in which the developer is adsorbed in a single-layer state of one grain or a two-layer state of two-grain lamination, for the sake of simplicity of explanation. It does not indicate that only one or two layers are present.

  As shown in FIG. 7, the proper toner concentration developer 68 is attracted to the surface of the developing sleeve 34 by the magnetic attractive force of the magnetic field (magnetic field) generated by the pumping pole piece 57 in the magnet roll 51. The proper toner concentration developer 68 pumped up forms a magnetic brush on the developing sleeve 34 by the magnetic field generated by the magnet roll 51. The magnetic brush is conveyed by the rotation of the developing sleeve 34 (the rotation direction is an arrow A in FIG. 7).

  The magnetic brush formed by the magnetic attraction force of the pumping pole piece 57 is adjusted after the amount of the proper toner concentration developer 68 is regulated by the developer regulating member 67 disposed to face the layer regulating pole piece 58. The two transport pole pieces 53 are sent to the development area near the development pole piece 54. In the developing area, the toner is transferred to the photoreceptor roll 71 and the photoreceptor roll 71 is developed.

  The low-toner-concentration developer 69 used for developing the photosensitive roll 71 and having a reduced toner density is developed by the first transport pole piece 55 existing on the downstream side of the development pole piece 54 as the developing sleeve 34 rotates. It is adsorbed on the surface of the sleeve 34 and collected in the developing device 61. The first transport pole piece 55 has a function of collecting the low toner concentration developer 69 and a function of transporting it.

  The region where the low toner concentration developer 69 peels is not on the pole of the transport pole piece 55 but in the vicinity of the interposition pole (dummy pole) piece 56 existing between the transport pole piece 55 and the pumping pole piece 58. Here, a series of development processes is completed.

(Developer carrier)
As shown in FIGS. 3 and 4, the developer carrier 31 according to the present invention has a plurality of magnet pieces (permanent magnets) having predetermined magnetic poles arranged (fixed) in the circumferential direction of the shaft 52. A magnet roll 51 having a predetermined magnetic field waveform and both ends of the shaft 52 of the magnet roll 51 are rotatably supported in the direction of arrow A in FIG. 6 via bearings (bearings) 33 and flanges 32. And a developing sleeve 34 of a nonmagnetic cylindrical body.

  More specifically, the flange 32 is fixed to both ends of the developing sleeve 34. A shaft 52 is inserted into the hollow portion (through hole) of the flange 32, and both end portions of the shaft 52 are rotatably supported by bearings 33 fixed to the flange 32. On the other hand, the magnet roll 51 in the developing sleeve 34 has a plurality of magnet pieces 53 to 58 (not shown) fixed to the peripheral surface of the shaft 52.

(Development sleeve)
As shown in FIGS. 3 to 5, the developing sleeve 34 is a hollow cylindrical part made of aluminum or stainless steel, and grooves 80 extending in the longitudinal direction (axial direction of the shaft 52) are arranged at substantially equal intervals in the circumferential direction. A groove forming portion 77 as a formed surface treatment portion, and a non-groove forming portion 78 as a non-surface treatment portion provided on both sides of the groove forming portion 77 and having no groove 80 formed thereon. .

  The outer diameter (2 × P in FIG. 5) of the non-groove forming portion 78 is larger than the diameter of the circle 86 (2 × R in FIG. 5) formed by connecting the bottoms 70 of the plurality of grooves 80 in the groove forming portion 77. The developing sleeve 34 is small and has a directionality in the rotational direction as shown in FIG. That is, the developing sleeve 34 makes the shape of the groove 80 asymmetric in the left-right direction on the paper surface (the inclination on the left side of the paper surface in the groove 80 in FIG. 5 is larger than the inclination on the right side of the paper surface), and is rotated in the direction of arrow A. The developer conveyance amount is increased.

  In such a developing sleeve 34, as shown in FIG. 4, when the developer carrier 31 is assembled with the magnet roll 51 inserted therein, if the direction of the developing sleeve 34 is reversed, the developer in the groove 80 is removed. The transport amount is greatly different (decreased).

  Therefore, in the developing sleeve 34 according to the present invention, as shown in FIGS. 3 and 4, a concave groove 79 continuous in the circumferential direction is formed in one non-groove forming portion 78. With this configuration, the operator can easily visually recognize the directionality of the developing sleeve 34, and the reverse mounting of the developing sleeve 34 can be prevented when assembling the developer carrier 31.

  Further, since the concave groove 79 is continuously formed in the circumferential direction in the non-groove forming portion 78, even if the developer enters the concave groove 79, the developer easily falls due to the rotation of the developing sleeve 34. . For this reason, the developer does not remain in the concave groove 79, and the non-groove forming portion 78 does not have a developer transport function. The width of the concave groove 79 is preferably larger than the diameter of the developer carrier. Further, when the groove 80 is processed on the surface of the developing sleeve 34 made of a nonmagnetic cylindrical body with a tool by the above-described configuration, a concave groove 79 continuous in the circumferential direction of the non-groove forming portion 78 is formed by the tool. it can. For this reason, when attaching the concave groove 79 to the surface of the developing sleeve 34, there is no need to provide an independent process.

  In Example 1, a tubular material made of an aluminum alloy (A3003) having a longitudinal length of 330 mm was used. The groove forming portion 77 (finished dimension) was 320 mm in length in the axial direction (left and right direction in FIG. 3 and FIG. 4), and 18.2 mm in outer diameter (outer diameter). Each of the two non-groove forming portions 78 has a length in the axial direction (left and right direction in FIG. 3 and FIG. 4) of 5 mm and an outer diameter (outer diameter) of 17.9 mm. The concave groove 79 has a width of 0.5 mm and a depth of 0.05 mm. The concave groove 79 is desirably larger than the diameter of the carrier (generally, 35 microns to 60 microns) from the viewpoint of easy visibility and difficulty in clogging the developer into the concave groove 79. The depth of the groove 80 was 0.1 mm. For this reason, the outer diameter (17.9 mm) of the non-groove forming portion 78 is smaller than the diameter (18.0 mm) of a circle 86 formed by connecting the bottoms 70 of the plurality of grooves 80 in the groove forming portion 77.

(Development sleeve manufacturing method)
Next, the manufacturing method of the developing sleeve according to the present invention will be described in detail below. (1) One end of a cylindrical tubular material made of a non-magnetic material as a base material is gripped by a processing device, and the tubular material is moved in the longitudinal direction. The groove 80 is formed on the outer peripheral surface of the groove forming portion 77 of the tube material by rotating the knurled tool against the tube material from a direction perpendicular to the longitudinal direction. (2) Next, the cutting tool provided in the vicinity of the cutting knurl tool is pressed against the pipe material from the direction perpendicular to the longitudinal direction, thereby finishing the surface of the groove forming portion 77 and the two non-groove forming portions 78. Do. (3) Next, a cutting tool is pressed against one non-groove forming portion to form a concave groove 79 continuous in the circumferential direction. (4) Finally, the cutting tool is pressed against the vicinity of the grip portion of the pipe material to cut off the product (developing sleeve 34).

  The above-described processing apparatus is a lathe having a function of conveying the pipe material in the longitudinal direction while rotating the pipe material in the circumferential direction and pressing the cutting knurled tool and the cutting bite tool against the pipe material from a direction perpendicular to the longitudinal direction of the pipe material. It ’s fine. In particular, a so-called Swiss lathe is suitable, and in this embodiment, a Swiss lathe was used.

  In the first embodiment, a cutting knurl (Quick knurling tool) single wheel type (A2 type) straight pattern manufactured by Swarovski Optic was used as the cutting knurl tool 16. Such a cutting knurled tool forms a straight groove 80 while cutting the outer peripheral surface of a pipe using a single cutter that is rotatable and has a sharp cutting edge, thereby minimizing the load on the machine and the pipe. In this way, the outer peripheral surface of the pipe material is knurled. The details are described in the September 2003 issue and the October 2004 issue of Taiga Publishing magazine (tool engineer).

(Magnet roll)
Next, the magnet roll that is placed inside the developing sleeve 34 will be described. The magnet roll described below is a so-called bonded magnet roll of a type in which a magnet piece using a magnetic resin material as a permanent magnet is bonded. The magnet piece can be molded by a known injection molding method or extrusion molding method. The magnetic resin material may be a sintered magnet. Furthermore, although the example which used the coil was given as a magnetic field orientation means mentioned later, the well-known thing using a rare earth-type permanent magnet may be used.

  FIG. 1 is a schematic structural view (perspective view) of the magnet roll 51, and FIG. 2 is a side view (arrow B) of the magnet roll 51 shown in FIG. The magnet roll 51 is obtained by laminating magnet pieces 53 to 58 having a substantially fan-shaped cross section (transverse section) in a radial direction on an outer peripheral surface of a shaft 52 using an adhesive.

  As shown in FIG. 2, the magnet roll 51 includes, in the circumferential direction of the shaft 52, the developing pole piece 54, the first transport pole piece 55, the interposition pole piece 56, the pumping pole piece 57, the layer regulating pole piece 58, and the second transport. The pole pieces 53 are bonded together in this order.

  The developing pole piece 54 has a function of developing the surface of the photoreceptor roll 71 with an appropriate toner concentration developer 68 adsorbed on the developing sleeve 34. The first transport pole piece 55 has a function of transporting at least the low toner concentration developer 69 adsorbed on the surface of the developing sleeve 34, and further has a function of recovering the low toner concentration developer 69. Also good.

  The first transport pole piece 55 of the first embodiment has both a function of collecting the low toner concentration developer 69 and a function of transporting it. The intervening pole piece 56 is provided adjacent to the first transport pole piece 55 and has a function of peeling the low toner concentration developer 69 from the surface of the developing sleeve 34. The pumping pole piece 57 is provided adjacent to the intervening pole piece 56 and has a function of adsorbing the appropriate toner concentration developer 68 to the surface of the developing sleeve 34.

  The second transport pole piece 53 has a function of sending the appropriate toner concentration developer 68 adsorbed on the surface of the developing sleeve 34 to the developing area near the developing pole piece 54. Since each of the magnet pieces 53 to 58 has an S-pole or N-pole magnetic pole on the outer peripheral surface thereof, the magnet roll 51 generates a magnetic field on the outer peripheral portion of the magnet roll. In FIG. 2, S represents the S pole and N represents the N pole.

(Method to generate magnetic field in magnet roll)
A known technique can be used as a method of generating a magnetic field in the magnet roll 51. An example is described below.
FIG. 8 schematically shows how the alignment magnetic field generated by the alignment coil 85 is converged by the alignment yoke 83 by magnetic lines of force. In order to generate a magnetic field in the magnet roll 51, magnetic poles are generated on the outer peripheral surfaces of the magnet pieces 53 to 58. These magnet pieces 53 to 58 are made of magnetic material powder, resin binder, additives, and the like. It is manufactured by molding in a magnetic field using a magnetic resin material made of a mixture. Here, the outer peripheral surface of the magnet piece is a surface that constitutes a part of the outer peripheral surface of the magnet roll and faces a part of the inner peripheral surface of the developing sleeve.

  As the magnet material powder, for example, a mixture of ferrite powder, rare earth metal powder such as Nd, and iron group metal powder such as Fe, Co, and Ni can be used. As the resin binder, for example, polyamide, polyethylene, polypropylene, epoxy resin, ethylene ethyl acrylate (EEA), or the like can be used.

  As shown in FIG. 8, each of the magnet pieces 53 to 58 is a mold apparatus including a fixed mold 81 having an orientation yoke 83 made of magnetic steel and a movable mold 82 movable with respect to the fixed mold. Manufactured using. Specifically, a magnetic resin material melted from a runner (not shown) communicating with one end in the longitudinal direction of the cavity 84 is formed inside the cavity 84 formed by clamping the fixed mold 81 and the movable mold 82. The cavity 84 is injected and filled with the molten magnetic resin material. At that time, an orientation magnetic field is generated by energizing the orientation coil 85, and the magnetic resin material filling the cavity 84 is cooled and solidified while orienting the magnet material powder in the magnetic resin material by this orientation magnetic field. Magnet pieces can be manufactured. Here, the cavity refers to a space inside the mold (a space having the shape of an injection molded product), and communication refers to making the two spaces continuous.

  Since this cooled and solidified molded article (magnet piece) is once cooled and solidified, the orientation state of the magnetic material powder does not change until the magnetic resin material is melted again. The magnetic field waveform can be almost reproduced. A magnetic flux having a high magnetic flux density is formed on the outer peripheral surface of the magnet piece in the vicinity where the converged orientation magnetic field shown in FIG. 8 is opposed to the cavity 84 and the orientation yoke 83 (near B in FIG. 8). Even in the absence of the orientation yoke 83, the magnetic poles can be formed on the outer peripheral surface of the magnet piece by energizing the orientation coil 85 to generate an orientation magnetic field. However, as shown in FIG. 8, since the orientation magnetic field is not converged by the orientation yoke 83, a magnetic pole having a lower magnetic flux density than the case of FIG. 8 is formed on the outer peripheral surface of the magnet piece.

  Although FIG. 8 has taken up and explained one magnet piece, other magnet pieces are manufactured in the same manner. However, in order to obtain a desired waveform, the position and shape of the orientation yoke 83 are generally changed. In addition, since the magnet material powder is not oriented unless the orientation coil 85 is energized, the magnetic poles may not be formed on the outer peripheral surface of the magnet piece even if the molding is performed using the mold apparatus shown in FIG. In this case, a magnetic pole is generated on the outer peripheral surface of the magnet roll by magnetization described later. However, since the magnet material powder is not oriented, a magnetic pole having a lower magnetic flux density is formed than the magnet piece without the orientation yoke 83 described above.

  The above is the method of generating (forming) magnetic poles on the outer peripheral surfaces of the magnet pieces 53 to 58. In the obtained magnet pieces 53 to 58, when the orientation coil 85 is energized, a magnetic pole is generated on the outer peripheral surface of each magnet piece. Yes.

  When the magnetic field waveform in the magnet roll 51 is further finely adjusted, or when the magnet piece is formed without energizing the orientation coil 85, the magnet piece is once demagnetized and an adhesive is applied around the shaft 52 to apply the magnet. After the pieces 53 to 58 are pasted to form a magnet roll, magnetization is performed. The timing of demagnetization may be demagnetized by passing a current in a direction opposite to the direction that was passed through the orientation coil 85 before magnetization from the mold (in-mold demagnetization). ), And may be demagnetized after removal from the mold.

  FIG. 9 is a schematic configuration diagram of the magnetizing apparatus. The magnetizing device 91 has a configuration in which a magnetizing yoke 93 is arranged in the vicinity of the magnetic pole to be generated on the outer peripheral surface of the magnet roll 51 in the yoke fixing mold 92. In FIG. 9, since the constituent magnetic poles of the magnet roll 51 are six poles (including the intervening pole Dm), six magnetizing yokes 93 are arranged. The magnetized yoke 93 and the yoke fixing die 92 are fixed by a known method such as a screw (not shown).

  The magnetizing yoke 93 is obtained by winding a magnetizing coil 95 around a magnetized iron core 94 so that the positional relationship between the magnetized iron core 94 and the magnetizing coil 95 is not shifted by the fixing resin 96. It is fixed. In FIG. 9, the magnetizing yokes 93 are separately (independently) fixed to the yoke fixing mold 92, but the magnetizing yokes 93 are in close contact with each other and are separated into separate magnetizing yokes. If this is difficult, a plurality of magnetized cores 94 and a plurality of magnetizing coils 95 may be fixed and formed as if they were one magnetized yoke using a fixing resin 96. A magnetizing magnetic field is generated by energizing the magnetizing coil 95 using the magnetizing mold 91 as described above, the magnet roll 51 is magnetized, and the magnet roll 51 generates a magnetic field.

Another embodiment of the present invention will be described with reference to FIG.
In order to make the description easy to understand, only the differences from the first embodiment will be described in detail, and the same parts as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  The difference between the second embodiment and the first embodiment is that the blast portion 87 as the surface treatment portion is blasted and the length of the non-blast portion 89 as the two non-surface treatment portions not subjected to the blast treatment. Is a different point. For example, in FIG. 9, the non-blast portion 89 has an axial length of 6 mm, and the non-blast portion 88 has an axial length of 4 mm.

  Even in such a developing sleeve 60, since the lengths of the two non-blast portions are different, the developing sleeve 60 has directionality in the rotational direction. That is, if the developing sleeve 60 is mistakenly attached to the developer carrying member 89, the developer is not transported to a portion where the developer should be transported, and the developer is transported to a portion where the developer is not transported. Therefore, an image quality defect occurs in an image forming apparatus using such a developer carrier.

  However, as shown in FIG. 9, since the concave groove 79 described in the first embodiment is formed in one non-blast portion 89, the same effect as in the first embodiment can be obtained.

A third embodiment according to the present invention will be described with reference to FIG.
In order to simplify the description, the same parts as those in the first embodiment or the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.

(Image forming device)
As shown in FIG. 10, the image forming apparatus according to the present invention is a so-called tandem digital color printer 131, and an image forming process unit 110 that forms an image corresponding to image data of each color, and an image forming process unit 110. And an image processing unit 140 that performs predetermined image processing on the image data received from the personal computer 102 or the image reading apparatus 103.

  The image forming process unit 110 includes four image forming units 111Y, 111M, 111C, and 111K that are arranged in parallel at a predetermined interval.

  Each of these image forming units 111Y, 111M, 111C, and 111K includes a photoreceptor roll 71 as a photoreceptor (image carrier) that forms an electrostatic latent image and carries a toner image, and this photoreceptor roll. Obtained by a charging device 113 that uniformly charges the surface of 71 with a predetermined potential, an LED print head 1 as an exposure device that exposes a photoreceptor roll 71 whose surface is charged by the charging device 113, and the LED print head 1. A developing device 61 that develops the electrostatic latent image, and a cleaner (blade) 116 that cleans the surface of the photoreceptor roll 71 after transfer.

  Further, a density detection circuit 117 that detects the toner image density of a test patch (density sample) formed on the photoreceptor roll 71 is provided in the vicinity of the downstream side of the developing device 61 so as to face the photoreceptor roll 71. It has been. The density detection circuit 117 is connected to the control unit 130 and outputs a toner image density detection value.

  Here, the image forming units 111Y, 111M, 111C, and 111K are configured in substantially the same manner except for the toner stored in the developing device 115. The image forming units 111Y, 111M, 111C, and 111K form yellow (Y), magenta (M), cyan (C), and black (K) toner images, respectively.

  In addition, the image forming process unit 110 includes an intermediate transfer belt 121 onto which the toner images of the respective colors formed on the photoreceptor rolls 71 of the image forming units 111Y, 111M, 111C, and 111K are transferred, and the image forming units 111Y. , 111M, 111C, and 111K toner images are sequentially transferred (primary transfer) to the intermediate transfer belt 121, and a primary transfer roll 122 as a primary transfer charging device and a superimposed toner image transferred onto the intermediate transfer belt 121 are recorded. A secondary transfer roll 123 as a secondary transfer charging device that performs batch transfer (secondary transfer) onto a paper P that is a material (recording paper), and a fixing device 125 that fixes the secondary transferred image onto the paper P. I have.

  The image forming process unit 110 performs an image forming operation based on a control signal such as a synchronization signal supplied from the control unit 130. At that time, image data input from the personal computer 102 or the image reading device 103 is subjected to image processing by the image processing unit 140 and supplied to each of the image forming units 111Y, 111M, 111C, and 111K via the interface. .

  For example, in the yellow image forming unit 111Y, the LED print head in which the surface of the photoreceptor roll 71 uniformly charged at a predetermined potential by the charging device 113 emits light based on the image data obtained from the image processing unit 140. 1, an electrostatic latent image is formed on the photoreceptor roll 71.

  This electrostatic latent image is developed by the developing device 61, and a yellow toner image is formed on the photoreceptor roll 71. Similarly, magenta, cyan, and black toner images are formed on the respective photoreceptor rolls 71 of the image forming units 111M, 111C, and 111K.

  The respective color toner images formed on the respective photoreceptor rolls 71 of the respective image forming units 111Y, 111M, 111C, and 111K are sequentially transferred by the primary transfer roll 122 onto the intermediate transfer belt 121 that rotates in the direction of arrow A in FIG. A toner image superimposed on the intermediate transfer belt 121 is formed by electrostatic attraction.

  The superimposed toner image is conveyed to an area (secondary transfer portion) where the secondary transfer roll 123 is disposed as the intermediate transfer belt 121 rotates. When the superimposed toner image is conveyed to the secondary transfer unit, the paper P is supplied to the secondary transfer unit in accordance with the timing at which the toner image is conveyed to the secondary transfer unit.

  Then, the superimposed toner images are collectively electrostatically transferred onto the conveyed paper P by the transfer electric field formed by the secondary transfer roll 123 in the secondary transfer portion. Thereafter, the sheet P on which the superimposed toner image is electrostatically transferred is peeled off from the intermediate transfer belt 121 and conveyed to the fixing device 125 by the conveying belt 124.

  The unfixed toner image on the paper P conveyed to the fixing device 125 is fixed on the paper P by being subjected to fixing processing by heat and pressure by the fixing device 125. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge placement unit (not shown) provided in the discharge unit of the digital color printer 131.

  That is, since the image forming apparatus according to the present embodiment includes the developing device 61 according to the present invention, an image quality defect (image quality failure) that is said to be a decrease in density due to poor peeling of the low toner concentration developer 69 from the developing sleeve. ) Can be extremely reduced.

  The above-described embodiments have been illustrated for the purpose of explanation, and the present invention is not limited thereto. The present invention can be recognized by those skilled in the art from the scope of the claims, the description, and the drawings. Changes, deletions, and additions are possible as long as they do not violate the technical idea.

  In the first embodiment described above, the developing sleeve in which the surface processing portion (groove forming portion) is grooved and the non-surface processing portion (non-groove forming portion) having the same axial length is provided on both sides thereof. However, the lengths in the axial direction of the non-surface treatment portion (non-groove forming portion) may not be the same.

  Further, in the above-described second embodiment, the developing sleeve or the like in which the surface treatment portion is subjected to blast processing is illustrated, but the surface treatment portion is subjected to other surface treatment, for example, chemical surface treatment. Also good.

The invention can also be grasped as follows.
[1] A groove forming portion in which grooves extending in the longitudinal direction are formed at substantially equal intervals in the circumferential direction;
Provided on both sides of the groove forming portion, and a non-groove forming portion in which the groove is not formed,
An outer diameter of the non-groove forming portion is smaller than a diameter of a circle formed by connecting bottoms of the plurality of grooves in the groove forming portion;
In the developing sleeve having directionality in the rotational direction,
A developing sleeve characterized in that a concave groove continuous in the circumferential direction is formed in one of the non-groove forming portions.

  With this configuration, when a groove or the like is formed on the surface of the developing sleeve made of a nonmagnetic cylindrical body with a tool, the tool can form a continuous groove in the circumferential direction in the non-groove forming portion. For this reason, it is not necessary to provide a separate process for attaching the groove to the developing sleeve as a means for visually confirming the directionality, which does not increase the cost. Further, since the concave groove is continuously formed in the circumferential direction, even if the developer enters the concave groove, the developer does not remain, so that the developer can be rotated in the rotation direction and / or the shaft. There is no conveyance in the direction (longitudinal direction).

[2] a surface treatment unit that has been subjected to a surface treatment for conveying a developer composed of toner and carrier;
Provided on both sides of the surface treatment unit, and a non-surface treatment unit not subjected to the surface treatment,
In the developing sleeve in which one of the non-surface treatment parts is longer than the other non-surface treatment part,
A developing sleeve, wherein one or the other non-surface-treated portion is formed with a continuous groove in the circumferential direction.

The present invention is applied to an image forming apparatus, a developing device, a developer carrier, and a developing sleeve used for a copying machine, a printer, and the like.

31 Developer carrier 34 Developing sleeve 51 Magnet roll 52 Shaft 53 Developing electrode piece 54 Collection electrode piece 55 Conveying electrode piece 56 Interposing electrode piece 57 Pumping electrode piece 58 Layer regulating electrode piece 61 Developing device 62 Housing 63 Developer stirring member 64 Developing Agent stirring member 67 Developer regulating member (layer thickness regulating member)
68 Proper toner concentration developer 69 Low toner concentration developer 71 Photoreceptor roll (photoreceptor)

Claims (5)

A surface treatment unit that has been subjected to a surface treatment for conveying a developer composed of toner and a carrier;
Provided on both sides of the surface treatment unit, and a non-surface treatment unit not subjected to the surface treatment,
In the developing sleeve having directionality in the rotational direction,
A developing sleeve characterized in that a concave groove continuous in the circumferential direction is formed in one of the non-surface-treated portions.   The developing sleeve according to claim 1, wherein a width of the concave groove is larger than a diameter of the carrier. The developing sleeve according to claim 1 or 2,
A developer carrier comprising a magnet roll inserted into the developing sleeve The developer carrying member according to claim 3,
A layer thickness regulating member provided facing the developer carrying member;
A developing device provided with a developer stirring member for stirring the developer in the housing A developing device according to claim 4;
An image forming apparatus comprising a photosensitive member facing the developer carrying member of the developing device

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