JP2006098882A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of forming a satisfactory image by making dispersion of toner in a developer comparatively uniform, and to provide an image forming apparatus using the developing device. <P>SOLUTION: Magnetic field generating means 44 and 45 are embedded in a part of the wall of a developer stir section 21, which is the wall of a developer container. The magnetic field generating means 44 and 45 are disposed such that an S-pole and an N-pole are opposite to each other with a stir member 23 between them. Straight magnetic force lines are formed between the opposite magnetic poles, and developer napping is formed along the magnetic force lines. The developer napping is formed to a considerable extend into the turning radius of the stirring member 23. When the developer is conveyed while being stirred by the stir member 23, the developer is passed through the developer naps. At this time, an action occurs such that supplied toner and the developer are urged to be stirred and dispersed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a two-component developing type developing device used in an image forming apparatus such as a printer or a facsimile.

  In general, a developing device using a two-component developer composed of magnetic particles (carrier) and toner is provided with a means for detecting a toner concentration which is a mixing ratio of the carrier and the toner, and the toner is adjusted so that the toner concentration is suitable for image formation. Image formation is performed while replenishing. The replenished toner is quickly mixed and stirred by the stirring member inside the developer container.

  At this time, it is desirable to disperse the replenished toner so that the inside of the developer container has a uniform toner density by mixing and stirring the replenished toner, but the toner is powder and stirring is insufficient. In some cases, the carrier and toner are not sufficiently charged by friction, the toner charge amount is insufficient, and the problem of image smearing occurs.

Therefore, as shown in FIG. 11, the magnetic field generating means 60 is embedded in a part of the wall surface of the developer stirring portion, the flexible member 61 is attached to the first stirring member 62, and the surface of the developer stirring portion is rubbed. There is a technique that promotes mixing and stirring of toner and developer (for example, see Patent Document 1). In the figure, reference numeral 62 denotes a second stirring member.
JP 2003-021951 A

  However, in the above-described technique, the south pole and the north pole are alternately arranged adjacent to each other, and a bundle of magnetic carriers on the bridge is formed in the developer conveyance path due to the form of magnetic force lines resulting therefrom. It will be. In such a configuration, the bundle of magnetic carriers cannot reach most of the developer within the radius of the conveying screw serving as the agitating / conveying means, and the dispersion and agitating action is not achieved by the screw blades of the first agitating member 62. It can only affect the developer near the outer edge. This state is shown in FIG.

  In view of such conventional problems, the present invention provides a developing device capable of forming a good image by making the toner dispersion state in the developer more uniform, and an image forming apparatus using the developing device. The purpose is to do.

  A developing device according to a first aspect of the present invention includes a developer conveyance path that conveys a developer composed of a magnetic carrier and toner, and an agitation conveyance unit that agitates and conveys the developer in the developer conveyance path. In the developing device, at least one set of magnetic field generation means having a pair of magnetic bodies of different polarities is provided in the developer conveyance path, and the magnetic field generated by the magnetic field generation means is the developer in the developer conveyance path. The magnetic force is applied in approximately one direction across the space for transporting the film.

  According to a second aspect of the present invention, in the developing device according to the first aspect, the pair of magnetic bodies are arranged to face each other across a space for transporting the developer in the developer transport path, and the pair of magnetic bodies is disposed. No other magnetic body for deflecting the direction of the magnetic force is provided in the vicinity.

  According to the third aspect of the present invention, in the developing device according to the first or second aspect of the present invention, within the range where the spikes of the developer containing the magnetic carrier are formed by the action of the magnetic force generated by the magnetic field generating means. A member for scraping off the developer is provided.

  According to a fourth aspect of the present invention, there is provided a developing device having a developer conveying path for conveying a developer composed of a magnetic carrier and a toner, and an agitating / conveying means for stirring and conveying the developer in the developer conveying path. The magnetic field generating means is provided in the developer conveying path, and the magnetic field generated by the magnetic field generating means causes a magnetic force to act in one direction in the space for conveying the developer in the developer conveying path. .

  According to a fifth aspect of the present invention, in the developing device according to the fourth aspect of the present invention, no other magnetic body that deflects the direction of the magnetic force is provided in the vicinity of the magnetic field generating means.

  According to the sixth aspect of the present invention, in the developing device according to the fourth or fifth aspect of the present invention, within a range where the spikes of the developer containing the magnetic carrier are formed by the action of the magnetic force generated by the magnetic field generating unit. A member for scraping off the developer is provided.

  According to the seventh aspect of the present invention, in a developing device having a developer transport path for transporting a developer composed of a magnetic carrier and toner, a magnetic field generating means is provided in the developer transport path, and the magnetic field generated by the magnetic field generating means is generated. Is characterized in that a magnetic force acts in one direction in a space for transporting the developer in the developer transport path.

  According to an eighth aspect of the present invention, in the developing device according to the seventh aspect, no other magnetic body for deflecting the direction of the magnetic force is provided in the vicinity of the magnetic field generating means.

  According to the ninth aspect of the present invention, in the developing device according to the seventh or eighth aspect, within a range where the spike of the developer containing the magnetic carrier is formed by the action of the magnetic force generated by the magnetic field generating means. A member for scraping off the developer is provided.

  An image forming apparatus according to a tenth aspect of the present invention uses any one of the developing devices according to the first to ninth aspects.

  According to the present invention, the developer and the toner can be sufficiently mixed and stirred to form a uniform dispersion state of the developer and the toner, thereby enabling good image formation.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming unit which is a main part of an image forming apparatus using a developing device according to the present invention. Around the drum-shaped photoconductor 10 as an image carrier, a developing device 12 and a transfer device are sequentially arranged from a roller-shaped charging device 11 provided on the left side in the drawing along a rotation direction indicated by an arrow A of the photoconductor 10. 13, a paper separation device 14 and a cleaning device 15 are provided.

  FIG. 2 is a schematic view of an image forming apparatus using the developing device of the present invention. When copying an original, as is well known, the original is set on the contact glass 101, and then a start button (not shown) is pressed to read the image on the original with the optical reading device 102. A sheet P is fed into the transfer device 13 from below as indicated by an arrow.

  On the other hand, the surface of the photoconductor 10 is uniformly charged by the charging device 11 as it rotates, and writing is performed by irradiating the surface with the laser light L from the optical writing device 103, and the above reading is performed on the photoconductor 10. Then, an electrostatic latent image corresponding to the original image is formed, and subsequently, the toner is attached when passing through the position of the developing device 12, and the electrostatic latent image is sequentially visualized. Then, the toner image formed by making this visible image is transferred by the transfer device 13 onto the paper P sent between the photoreceptor 10 and the transfer device 13 as described above. After the transfer, the paper P is discharged by the paper separation device 14 and separated from the electrostatically adhering photoconductor 10, conveyed to the fixing device 104, where the transferred image is fixed, and discharged to the paper discharge unit 105. To do. A separation claw may be provided in place of the paper separation device 14 and mechanically separated from the photoreceptor 10. On the other hand, after the image transfer, the photosensitive member 10 is cleaned by scraping off the residual toner remaining on the surface with a cleaning blade 17 provided in the cleaning device 15, and then neutralized with an unillustrated neutralizing lamp to initialize the surface potential. Turn into.

  In the image forming apparatus, the photosensitive member 10, the charging device 11, the developing device 12, the cleaning device 15 and the like described above are integrated in a single cartridge case 19 as shown in FIGS. Also good. 3 shows the process cartridge 20 provided in the image forming apparatus shown in FIG. 1 as viewed from the side opposite to the photoreceptor 10, and FIG. Although not shown, the process cartridge 20 is attached between side plates provided facing the front and rear in the image forming apparatus main body 100 and is detachably set. As shown in FIGS. 3 and 4, the process cartridge 20 is provided with a photosensitive shutter 18 that can be freely opened and closed. Then, in the state where it is set in the image forming apparatus main body 100, as shown in FIG. 3, the photosensitive member shutter 18 is opened, the transfer device 13 and the sheet separating device 14 side of the photosensitive member 10 are opened, and it is not set. In the state, the photoconductor shutter 18 is closed and the photoconductor 10 is covered as shown in FIG.

  In such an image forming apparatus, the developing device 12 described above is configured by providing a developer agitating unit 21 on the lower side of the developer container and a developer carrying unit 22 on the upper side as shown in FIG. . The developer stirring unit 21 is provided with a first stirring member 23 and a second stirring member 24 that transport the two-component developer while stirring. Although not shown, a toner concentration sensor that detects the mixing ratio between the toner in the developer and the carrier from, for example, magnetic permeability is provided. Further, as shown in FIG. 5, the developer agitation unit 21 is provided with a new toner replenishing port 25 and a recycled toner replenishing port 26 opened on one side thereof, respectively. Then, the toner entering from the replenishing ports 25 and 26 is conveyed so as to circulate through the first stirring member 23 and the second stirring member 24. In addition, the space which accommodates the 1st stirring member 23 has covered the upper surface with the top wall 21a which a part is fractured | ruptured in FIG. Moreover, the space which accommodates the 2nd stirring member 24 is provided with the opening 50, and opened upwards.

  On the other hand, as shown in FIG. 1, the developer carrying portion 22 is provided with a developing roller 28 at a position facing the photoreceptor 10 through the developing window 27. Further, a developing doctor 29 for controlling the amount of developer supplied to the photoconductor 10 is provided. Then, after the developer fed from the developer agitating unit 24 through the opening 50 is carried by the developing roller 28, it is made uniform by the developing doctor 29, and the toner in the made uniform developer is attached to the photoreceptor 10. . The cleaning device 15 provided on the photoconductor 10 includes a screw-like toner conveying member 30 that conveys residual toner scraped off by the cleaning blade 17 in the cleaning case portion 15 a of the cartridge case 19. Arrange in the direction. As shown in FIG. 3, the toner conveying member 30 is provided such that one end portion 31 a of the shaft portion 31 enters the dropping passage 35 from a dropping passage inlet 33 provided on the upper side of the front plate portion 19 a of the cartridge case 19. The fall path 35 is provided with a peripheral wall 36 on the outer surface of the front plate portion 19a so as to surround the fall path 35, and the front side thereof is hermetically covered with a front cover which is removed and omitted in FIG. The dropping path 35 is provided with a dropping path outlet 37 that communicates with the recycled toner supply port 26 of the developing device 12 described above on the bottom surface 36 a of the peripheral wall 36. Further, the peripheral wall 36 is partially inclined between the falling path outlet 37 and the falling path entrance 33 to form a residual toner falling surface 36b on the inner surface of the inclined portion.

  In the developing device 12, a driving motor (not shown) is driven at the time of development, the driving is transmitted to rotate the developing roller 28, and the first stirring member 23 and the second stirring member 24 are rotated to stir the developer. The toner and the carrier are conveyed to the developing roller 28 while being frictionally charged. On the other hand, a predetermined bias is applied to the developing roller 28 so that the toner in the developer is electrostatically attached to the surface of the photoreceptor 10 and the latent image on the surface is visualized. In the cleaning device 15, the screw gear 40 coaxial with the toner conveying member 30 meshes with the photosensitive gear 43 coaxial with the photosensitive member 10 via two idler gears 41 and 42 as shown in FIG. Then, as indicated by arrows in FIG. 6, the screw gear 40 is rotated in the reverse direction along with the rotation of the photoconductor gear 43, the toner conveying member 30 is rotated in the reverse direction with respect to the photoconductor 10, and residual toner removed from the photoconductor 10 is removed. The toner is conveyed by the toner conveying member 30 and collected on the front side in the cleaning case portion 15a, dropped from the dropping path entrance 33 onto the dropping surface 36b as indicated by an arrow in FIG. 2, and further on the dropping surface 36b as indicated by an arrow. The toner is slid down and collected in the developer agitating unit 21 through the recycle toner supply port 26 from the drop path outlet 37.

  FIG. 7 is a diagram showing a main part of the first embodiment of the developing device according to the present invention, in which magnetic field generating means 44 and 45 are embedded in a part of the wall surface of the developer agitating unit 21 which is a developer container wall surface. As can be seen from FIG. 8, the magnetic field generating means 44 and 45 are configured such that the S pole and the N pole face each other with the stirring member 23 interposed therebetween. With this configuration, linear magnetic lines of force are formed between the opposing magnetic poles (FIG. 8A), and developer spikes are formed along the lines of magnetic force (FIG. 8B). That is, the rising of the developer enters a considerable area within the rotation radius of the stirring member 23. When the developer is conveyed while being stirred from the left to the right in FIG. 7 by the stirring member 23, the developer passes through the spikes of the developer as shown in FIG. 8B. At this time, stirring and dispersion of the replenished toner and developer are promoted.

  FIG. 9 is a diagram showing a main part of the developing device according to the second embodiment of the present invention. Magnetic field generating means 46 and 47 are embedded in a part of the wall surface of the developer stirring unit 21 which is a developer container wall surface. Similarly to the example shown in FIG. 7, the magnetic field generating means 46 and 47 are arranged such that the respective S poles and N poles are arranged along the developer conveying direction with the stirring member 23 interposed therebetween, and the magnetic poles of one of the magnetic field generating means The magnetic poles of the other magnetic field generating means are configured such that different poles face each other. With this configuration, two sets of developer spike areas can be formed even with one set of magnetic field generating means, and therefore, the dispersion and stirring action can be further enhanced.

  FIG. 10 is a diagram showing a main part of the third embodiment of the developing device according to the present invention, in which a scraping member 48 is formed integrally with the stirring member 23, and the head is raised in the developer heading area. A strong stress is given to the developer while scraping, and the friction electric resistance of the developer is further promoted. The scraping member 48 may or may not be provided with a gap from the wall surface of the developer stirring unit 21. However, when no gap is provided, it is desirable that the scraping member has flexibility.

  In addition, although only the 1st stirring member 23 was demonstrated in the said embodiment, this invention may be used for any of the 1st stirring member 23 and the 2nd stirring member 24, and can also be used for both.

Sectional drawing which shows schematic structure of the image forming part which is the principal part of the image forming apparatus using the image development apparatus concerning this invention. Schematic sectional view of an image forming apparatus using the developing device of the present invention 1 is a perspective view showing a process cartridge provided in the image forming apparatus shown in FIG. 1 when viewed from the side opposite to the photoreceptor. Similarly perspective view seen from the photoconductor side The perspective view which similarly shows the developer stirring part of a developer container The figure which shows rotation of the roller in the developing device The figure which shows the principal part of Example 1 of the developing device which concerns on this invention. Sectional view (A) showing lines of magnetic force of Example 1 and sectional view (B) showing spikes of developer The figure which shows the principal part of Example 2 of the developing device which concerns on this invention. The figure which shows the principal part of Example 3 of the developing device which concerns on this invention. Sectional view (A) showing lines of magnetic force of conventional example and sectional view (B) showing spikes of developer

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Photoconductor 11 Charging device 12 Developing device 13 Transfer device 14 Paper separation device 15 Cleaning device 17 Cleaning blade 18 Photosensitive shutter 19 Cartridge case 20 Process cartridge 21 Developer stirring portion 22 Developer carrying portion 23 First stirring member 24 Second Stirring member 25 New toner supply port 26 Recycled toner supply port 27 Developing window 28 Developing roller 29 Developing doctor 30 Toner conveying member 33 Dropping path inlet 35 Dropping path 36 Peripheral wall 36b Residual toner dropping surface 37 Dropping path outlet 40 Screw gear 41, 42 idler gear 43 photoconductor gear 44, 45 magnetic field generating means 46, 47 magnetic field generating means 48 scraping member 50 aperture 100 image forming apparatus main body 101 contact glass 102 optical reading apparatus 103 optical writing apparatus P paper

Claims (10)

In a developing device having a developer transport path for transporting a developer composed of a magnetic carrier and toner, and a stirring transport means for stirring and transporting the developer in the developer transport path.
The developer transport path is provided with at least one set of magnetic field generating means having a pair of magnetic bodies of different polarities, and the magnetic field generated by the magnetic field generating means is a space for transporting the developer in the developer transport path. A developing device characterized in that a magnetic force is applied substantially in one direction across the surface. 2. The developing device according to claim 1, wherein the pair of magnetic bodies are disposed to face each other with a space for transporting the developer in the developer transport path, and the direction of the magnetic force is deflected in the vicinity of the pair of magnetic bodies. A developing device characterized in that no other magnetic material is provided. 3. The developing device according to claim 1 or 2, wherein a member that scrapes off the developer spike within a range in which the developer spike containing the magnetic carrier is formed by the action of the magnetic force generated by the magnetic field generating means. And a developing device. In a developing device having a developer transport path for transporting a developer composed of a magnetic carrier and toner, and a stirring transport means for stirring and transporting the developer in the developer transport path.
A development characterized in that a magnetic field generating means is provided in the developer transport path, and the magnetic field generated by the magnetic field generating means causes a magnetic force to act in one direction in a space for transporting the developer in the developer transport path. apparatus. 5. The developing device according to claim 4, wherein no other magnetic material for deflecting the direction of the magnetic force is provided in the vicinity of the magnetic field generating means. 6. The developing device according to claim 4 or 5, wherein a member that scrapes off the developer spikes within a range where the developer spikes including the magnetic carrier are formed by the action of the magnetic force generated by the magnetic field generating means. And a developing device. In a developing device having a developer transport path for transporting a developer composed of a magnetic carrier and toner,
A development characterized in that a magnetic field generating means is provided in the developer transport path, and the magnetic field generated by the magnetic field generating means causes a magnetic force to act in one direction in a space for transporting the developer in the developer transport path. apparatus. 8. The developing device according to claim 7, wherein no other magnetic material for deflecting the direction of the magnetic force is provided in the vicinity of the magnetic field generating means. 9. The developing device according to claim 7 or 8, wherein a member that scrapes off the developer spike within a range in which the developer spike including the magnetic carrier is formed by the action of the magnetic force generated by the magnetic field generating means. And a developing device. An image forming apparatus using the developing device according to claim 1.