This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2007-260105 filed on Oct. 3, 2007.
1. Technical Field
The present invention relates to a member for agitating and conveying a developer, a developing device, and an image forming apparatus using the same
2. Related Art
Generally, in image forming apparatuses using an electronic photographing method or an electrostatic recording method, a developing device that develops an electrostatic latent image formed on an electrostatic latent image carrier such as a photosensitive drum is used. As such a developing device, for example, so-called two-component developing devices in which two-component developer (hereinafter, simply referred to as a developer) including a carrier having magnetism and toner having a resin as its primary component are housed in a developing housing having a developing opening facing the electrostatic latent image carrier, a developer holding member (for example, a developing roll) is disposed to face the developing opening of the developing housing, and an auger that conveys the developer inside the developing housing to a developing roll while agitating and conveying the developer is disposed on the rear side of the developing opening of the developing housing have been widely used.
In developing devices of this type using the two-component developing method, it is required to dissolve aggregated toner while supplying toner consumed by a developing operation and to stably convey and supply the developer to the developer holding member.
According to an aspect of the invention, there is provided a member for agitating and conveying a developer, including: a rotation shaft that rotates in a given direction; a spiral-shaped conveying member that is disposed on an outer circumferential surface of the rotation shaft; and conveys a developer in a shaft direction of the rotation shaft; a protruded agitation section that protrudes, with a gap from the rotation shaft, from the spiral-shaped conveying member toward an upstream side in a developer conveying direction; and agitates the developer; and a diameter directional conveying section that is disposed between adjacent spires of the spiral-shaped conveying member; is disposed in a downstream side in the developer conveying direction with respect to the protruded agitation section, and gives a diameter directional conveying force to the developer.
Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein:
Hereinafter, an embodiment of the present invention will be described.
[Overview of Image Forming Apparatus]
First, a schematic configuration of an image forming apparatus according to an embodiment of the present invention will be described with reference to
To this image forming apparatus 100, color image information of a color document read out by an image reading device 102, color image information transmitted from a personal computer, an image data input device, or the like which is not shown in the figure, and the like are input. The image forming apparatus 100 is configured to perform an image process for the input image information.
In
Here, the image reading device 102 is configured to illuminate the document placed on a platen glass by using a light source not shown in the figure and read out an image reflected from the document through a scanning optical system with a given resolution by using an image reading component constituted by a CCD sensor or the like.
The image forming units 1Y, 1M, 1C, and 1K has a same configuration. Basically, the image forming units 1Y, 1M, 1C, and 1K include photosensitive drums 2Y, 2M, 2C, and 2K which rotate at a given rotation speed along directions of arrows, charging rolls 3Y, 3M, 3C, and 3K serving as a charging unit for uniformly charging surfaces of the photosensitive drums 2Y, 2M, 2C, and 2K, exposure devices 4Y, 4M, 4C, and 4K which form electrostatic latent images by exposing images corresponding to each color on the surfaces of the photosensitive drums 2Y, 2M, 2C, and 2K, developing devices 5Y, 5M, 5C, and 5K which develop the electrostatic latent images formed on the photosensitive drums 2Y, 2M, 2C, and 2K, toner cartridges 10Y, 10M, 10C, and 10K which are detachably attached and supply toners of given colors to the developing devices 5Y, 5M, 5C, and 5K, drum cleaning devices 7Y, 7M, 7C, and 7K, and the like.
According to this embodiment, in the photosensitive drums 2Y, 2M, 2C, and 2K, photosensitive layers made of an organic photosensitive material, an amorphous selenium-based photosensitive material, an amorphous silicon-based photosensitive material, or the like are formed on the surfaces of drums made of a metal material which rotate in the direction of the arrows, and the charging rolls 3Y, 3M, 3C, and 3K are brought into contact with the surfaces of the photosensitive drums 2Y, 2M, 2C, and 2K so as to charge the photosensitive layers to have a given electric potential.
An image forming process in the image forming apparatus having the above-described configuration for a case where the image forming unit 1Y forms a yellow toner image will be described as a representative example.
First, the surface of the photosensitive drum 2Y is charged uniformly by the charging roll 3Y. Next, scanning exposure corresponding to a yellow image is performed by a laser beam output from the exposure device 4Y, for example, based on the image information read out by the image reading device 102, and thereby an electrostatic latent image corresponding to the yellow image is formed on the surface of the photosensitive drum 2Y.
The electrostatic latent image corresponding to this yellow image is formed as a yellow toner image by the developing device 5Y and is transferred primarily on the intermediate transfer belt 9 depending on a pressure contact force and an electrostatic attraction force of the primary transfer roll 6Y constituting a part of the primary transferring unit. Yellow toners remaining on the photosensitive drum 2Y after the primary transfer are scraped out by the drum cleaning device 7Y. Thereafter, the surface of the photosensitive drum 2Y is electrically neutralized by a neutralization device 8Y and then, charged again by the charging roll 3Y for the next image forming cycle.
According to the image forming apparatus 100 forming a multiple color image, the above-described image forming process is performed in image forming units 1M, 1C, and 1K at timings in consideration of relative positional differences of the image forming units 1Y, 1M, 1C, and 1K, and a full-color toner image is formed on the intermediate transfer belt 9 in an overlapped state. As the intermediate transfer belt 9, for example, a belt that is formed in an endless shape by forming a synthetic resin film such as polyimide having flexibility in a band shape and connecting both ends of the synthetic resin film formed in the band shape in the longitudinal direction together by a welding means or the like may be used.
The full-color toner image that has been primarily transferred on the intermediate transfer belt 9 is secondarily transferred on the recording sheet 18 that is conveyed to a secondary transfer position at a given timing depending on a pressure contact force and an electrostatic attraction force between a backup roll 13 supporting the intermediate transfer belt 9 and a secondary transfer roll 12 that is pressingly contacted with the backup roll 13 at a given timing. The remaining toners on the intermediate transfer belt 9 which could not be secondarily transferred on the recording sheet 18 are conveyed to the belt cleaning device 14 in a state of being attached on the intermediate transfer belt 9 and removed from the intermediate transfer belt 9 by the belt cleaning device 14, and thereby a next image forming process is prepared.
The recording sheet 18 of a given size is fed from a paper feed cassette 17 serving as a recording sheet accommodation unit, which is disposed in a lower portion of the image forming apparatus 100, by a paper feed roll 17a. The fed recording sheet 18 is conveyed to a secondary transfer position of the intermediate transfer belt 9 at a given timing by a plurality of conveying rolls 19 and resist rolls 20. On the recording sheet 18, as described above, a full-color toner image is transferred in aggregate from the intermediate transfer belt 9 by the backup roll 13 and the secondary transfer roll 12 serving as a secondary transferring unit.
The recording sheet 18 on which the full-color toner image is secondarily transferred from the intermediate transfer belt 9 is separated from the intermediate transfer belt 9 and then is conveyed to the fixing device 15 that is disposed on the down stream side of the secondary transferring unit. Then, the toner image is configured to be fixed on the recording sheet 18 depending on heat and pressure by this fixing device 15. The recording sheet 18 after the fixing process is discharged on a discharge tray 24 through a discharge roll 23.
[Developing Device]
Next, the configuration of a developing device according to an embodiment of the present invention will be described with reference to
As shown in
According to this embodiment, the developing roll 52 includes a developing sleeve 521 that rotates in a given direction (in this example, the clockwise direction) in a developing process and a magnet roll 522 that is installed to be fixed inside this developing sleeve 521.
Here, the developing sleeve 521 is disposed to rotate in a given direction and to face the photosensitive drum 2 with a given distance maintained therebetween in an area (developing area) that is an opening portion of the developing housing 51 and faces the photosensitive drum 2. To this developing sleeve 521, a bias power source (not shown) for applying a developing bias formed by a DC bias that is generated by superposing alternating currents is connected.
The magnet roll 522 according to this embodiment is formed in a roll shape by disposing a plurality of magnet members in a circumferential direction. The magnet roll 522 includes conveying magnetic poles N1 or pickoff magnetic poles S2 which are disposed on the downstream side of the developing magnetic pole S1, for example, with a given angular intervals therebetween and trimming magnetic poles N2 or pickup magnetic poles S3 on the upstream side of the developing magnetic pole S1, along the developing magnetic pole S1 and the rotation direction of the developing roll 52 which are disposed in correspondence with developing areas The disposition or the number of magnetic poles inside the magnet roll 522 may be appropriately selected.
In addition, below the trimming magnetic pole N2 disposed inside the developing roll 52, a layer-thickness regulation member 54 of an approximate “<” shape which extends along the direction of the shaft of the developing roll 52 such that the facing side of the layer-thickness regulation member closely approaches the developing roll 52 with a given gap is disposed, and is configured to regulate the two-component developer on the developing roll 52 at a given amount (layer thickness).
As clearly shown in
According to this embodiment, the supply auger 56 housed in the first developer housing section 53a has a spiral-shaped blade 56b that agitates and conveys the two-component developer in the direction of the rotation shaft 56a (in
In addition, the admix auger 57 housed in the second developer housing section 53b has a spiral-shaped blade 57b formed on the circumference of the rotation shaft 57a for agitating and conveying the two-component developer in a direction opposite to that of the supply auger 56 (in
[Member for Agitating and Conveying Developer]
The detailed configuration and function of an admix auger 57 of a member for agitating and conveying a developer according to an embodiment of the present invention will be additionally described with reference to
As shown in
As shown in
The developer introduced on the rotation shaft side is agitated and conveyed (arrow c) on the circumference of the rotation shaft by the plate-shaped section 575 disposed on the downstream side, and thereby soft blocking for the toner is released and a conveying force in the shaft direction is weakened by the plate-shaped section 575. Accordingly, developer staying between the spiral-shaped blades 57b1 and 57b2 is forced to be forwarded in the outer circumferential direction (arrow d1) again, and thereby soft blocking is released by the above-described action of the protrusion section 570 overlapped in the shaft direction. For the developer (arrow d2) introduced into the outer circumferential area not overlapped with the protrusion section 570, soft blocking is released by action of the circumferential part of the spiral-shaped blade 57b2 disposed on the downstream side or another protrusion section 570.
Although the number of the above-described auxiliary agitating and conveying pair 570 and 575 may be one, however, a plurality of the auxiliary agitating and conveying pairs disposed in the shaft direction can dissolve soft blocking for the toner more assuredly. In addition, the numbers of the protrusion sections 570 and the plate-shaped sections 575 may not be the same for forming the pairs, and the numbers thereof may be appropriately selected. For example, the number of the plate-shaped sections 575 may be smaller than that of the protrusion sections 570 for suppressing stay of the developer in the shaft direction.
In addition, although the protrusion section 570 may be disposed to extend over the spiral-shaped blades 57b1, 57b2, however, it is preferable that the protrusion section is formed to extrude in the shaft direction from the outer circumferential surface of the spiral-shaped blade 57b toward the upstream side of the conveying direction of the developer, in view of acquiring a smooth flow of the developer by suppressing stay of the developer which is caused by weakening the conveying force in the shaft direction due to application of the conveying force for conveying the developer in the radial direction of the rotation shaft 57a over the blades. Here, the outer circumferential surface of the spiral-shaped blade 57b includes not only the outer circumferential edge of the spiral-shaped blade 57b but also an area near the outer circumferential edge of the spiral-shaped blade 57b, that is, the outer circumferential edge of the spiral-shaped blade 57b and the surface of the blade 57b positioned from the outer circumferential edge to the rotation shaft 57a side.
In addition, although the plate-shaped section 575 is not needed to be disposed over the spiral-shaped blades 57b1 and 57b2, it is preferable that the plate-shaped section is disposed over the spiral-shaped blades 57b1 and 57b2 in the shaft direction of the rotation shaft 57a. In such a case, since there is no gap between the spiral-shaped blades 57b1 and 57b2 in the shaft direction, stay of the developer on the circumference of the rotation shaft without application of the conveying force in the radial direction of the rotation shaft 57a by the developer's passing through a space between the blade 57b1 and the plate-shaped section 575 or a space between the blade 57b2 and the plate-shaped section 575 in the direction of the rotation shaft and getting out of the plate-shaped section 575 can be suppressed in a case where the plate-shaped section 575 conveys the developer in the radial direction of the rotation shaft 57a.
In addition, as shown in
In view of effectively suppressing the stay of the developer in the shaft direction, it is preferable that the height (thickness) A of the protrusion section 570 in the diameter direction is equal to or smaller than half the height (thickness) C of the spiral-shaped blade 57b in the diameter direction.
In addition, it is preferable that the phases of the protrusion section 570 and the plate-shaped section 575 with respect to the center of rotation are different from each other. As described above, by setting the dispositional phases of the protrusion section 570 and the plate-shaped section 575 differently, it is possible to suppress the stay of the developer. In addition, in view of acquiring a smoother flow of the developer in the shaft direction, it is preferable that the phases of the protrusion section 570 and the plate-shaped section 575, as shown in
In addition, as shown in
In view of performing an action for separating the developer into the outer circumferential side and the rotation shaft side more smoothly by using the protrusion section 570, as shown in
Referring back to
Generally, when the protrusion section 570 and the plate-shaped section 575 are provided up to the mixing area D, stay of the developer in the area is promoted, and a phenomenon that the supplied toner floats above the staying developer occurs. Thus, by disposing the above-described mixing area D having a lowered density of the developer on the upstream side of the agitating and conveying area in which the protrusion section 570 and the plate-shaped section 575 are disposed, the supplied toner and the circulating developer can be mixed and agitated uniformly.
In particular, this mixing area D is formed as an area having one pitch or more of the blade 57b of the end portion of the admix auger 57 on the upstream side corresponding to the opening portion of the partitioned wall W that is a communication portion between the first developer housing section 53a and the second developer housing section 53b. It is preferable that the mixing area is formed as two to three-pitch area.
For the mixing area D in which the density of the developer is lowered, an embodiment in which the protrusion section 570 and the plate-shaped section 575 are not disposed as described above may be used. However, the mixing area D may be aggressively formed so as to lower the density of the developer by forming the auger pitch (pitch of the blade 57b) to be larger than the pitch of the blade on the downstream side or forming the diameter of the auger shaft (rotation shaft 57a) to be smaller than that on the downstream side.
In addition, in order to appropriately supply the toner based on the developing operation, the density of the developer flowing in the shaft direction is preferably measured, and accordingly, it is preferable that the protrusion section 570 and the plate-shaped section 575 which reduce the conveying force in the shaft direction by applying a conveying force in a radial direction of the rotation shaft 57a are not disposed in the vicinity of the density sensor Sd (see
In other words, in this embodiment, it is preferable to set the protrusion section 570 and the plate-shaped section 575 as an area located on the downstream side of the mixing area D and the upstream side of the density sensor Sd.
As another embodiment of the mixing area D in which the supplied toner and circulating developer are mixed, for example, as shown in
As another embodiment, for example, as shown in
In addition, regarding the above-described rib 590, parts of the ribs 590a may be disposed to be tilted as shown in
In addition, application of the member for agitating and conveying a developer according to an embodiment of the present invention is not limited to the above-described developing apparatus, and it is possible to apply it as a member for agitating and conveying a developer, which is disposed in a developer conveying path for agitating and conveying the developer. In addition, although each embodiment (detailed example) may be performed individually, it is apparent that the above-described embodiments may be performed in combination.
Number | Date | Country | Kind |
---|---|---|---|
2007-260105 | Oct 2007 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
4980724 | Tanaka | Dec 1990 | A |
5228775 | Horn et al. | Jul 1993 | A |
5758238 | Mordenga et al. | May 1998 | A |
6275674 | Sugimoto | Aug 2001 | B1 |
20040179865 | Nishiyama | Sep 2004 | A1 |
20040265009 | Shigeta et al. | Dec 2004 | A1 |
20050123321 | Buhay-Kettelkamp et al. | Jun 2005 | A1 |
20070048023 | Thompson et al. | Mar 2007 | A1 |
20070122203 | Sugimoto et al. | May 2007 | A1 |
Number | Date | Country |
---|---|---|
03-265877 | Nov 1991 | JP |
5-43163 | Feb 1993 | JP |
11-052727 | Feb 1999 | JP |
2002-148915 | May 2002 | JP |
2003-295589 | Oct 2003 | JP |
3500920 | Dec 2003 | JP |
2005-326480 | Nov 2005 | JP |
2006-126484 | May 2006 | JP |
2006349732 | Dec 2006 | JP |
2007225854 | Sep 2007 | JP |
Number | Date | Country | |
---|---|---|---|
20090092419 A1 | Apr 2009 | US |