JP2006171557A - Developing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing apparatus capable of removing toner remaining on a developing sleeve after developing at a low cost. <P>SOLUTION: Regarding the developing apparatus 32 using one-component toner, the apparatus has the developing sleeve 60 which is rotated while carrying the toner, a layer thinning means 62 located on the upstream side of a developing position 64 so as to make the toner layer on the developing sleeve thin, and a non-conductive toner hysteresis removing part 66 located on the downstream side of the developing position 64 so as to shift the residual toner brought in press contact with the developing sleeve 60. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing device used in an image forming apparatus such as a printer, a copying machine, or a facsimile, and an image forming apparatus having the developing device.

  In an image forming apparatus, a developing device using one component toner is known. The developing portion of the thin toner formed on the developer (toner) holding body (developing sleeve) is developed and consumed at the developing position. Thereafter, the toner is again supplied onto the developing sleeve, and a new thin layer toner is formed on the developing sleeve by the toner thinning device. However, the thin layer toner in the non-development portion on the development sleeve is not consumed at the development position and passes through the toner thinning device again. Differences in the toner amount on the developing sleeve, the toner charge amount, and the adhesion force of the thinned toner to the developing sleeve occur between the developed portion and the non-developed portion, resulting in a difference in image density. There was an image failure called. Further, when the toner is held on the developing sleeve for a long period of time, the shape of the toner itself is deteriorated and the external additive added to the toner is peeled off.

  To address these problems, in developing devices that use non-magnetic one-component toner, a conductive elastic material made of foam or the like is brought into contact with the developing sleeve and a voltage for discharging is applied to all toners on the developing sleeve. Thus, a developing device is disclosed in which the toner is neutralized and easily separated from the developing sleeve (Patent Document 1).

JP-A-11-212365

  However, the developing device disclosed in Patent Document 1 uses a voltage application device, and the voltage application amount for static elimination is excessive due to a change in the resistance value of the conductive material or a change in the toner charge amount due to a change in use environment. In such a case, leakage between the developing sleeve and the conductive elastic material may occur, or the effect due to insufficient charge injection amount may be reduced.

  An object of the present invention is to improve an image failure caused by a development history of toner on a developing sleeve without using an electric means.

  In order to solve the above-described problems, the present invention is characterized in that, in a developing device using one-component toner, a developing sleeve that carries toner and rotates, and a developing sleeve on the upstream side of the developing position on the developing sleeve. A developing device comprising: a thinning means for thinning the toner; and a non-conductive toner history removing unit that moves the residual toner that is downstream of the developing position and that is pressed against the developing sleeve. It is in. Thus, the development history can be removed by the movement of the residual toner on the developing sleeve after development, that is, movement on the surface of the developing sleeve or dropping from the developing sleeve by the mechanical action of the toner history removing unit. Therefore, it is possible to improve the image trouble without providing a special means.

  Preferably, the developing device is a magnetic one-component toner. That is, even in the case of toner having magnetism, the development history of the toner on the development sleeve after development can be removed by the mechanical action of the toner history removal unit.

  Preferably, the toner history removing unit is a developing device having irregularities on the surface. Thereby, the effect of exchanging the upper and lower layers of the toner on the developing sleeve and the effect of exchanging the toner between the developing part and the non-developing part can be obtained by the scattering (disturbing) action due to the unevenness of the surface of the toner history removing part. That is, the history removing action can be generated by stirring the toner on the developing sleeve after development by the toner history removing unit.

  Preferably, the toner history removing unit is a developing device provided in an elastic member and pressed against the developing sleeve by the urging force of the elastic member. Accordingly, it is possible to perform uniform pressure contact with the developing sleeve of the toner history removing unit by the biasing force of the elastic member. Accordingly, it is possible to improve the scraping action of the toner on the developing sleeve by uniform pressure contact, and to reduce the toner adhesion amount on the developing sleeve. Since a large amount of toner is newly supplied to the developing sleeve having a reduced toner adhesion amount, the development history on the developing sleeve can be made harder to remain.

  Preferably, the developing device has a toner passage hole formed in the elastic member. As a result, the toner scraped off from the developing sleeve passes through the toner passage hole provided in the elastic member, returns to the developing chamber, is mixed with the newly supplied toner in the developing chamber again, and is agitated to remove the development history. can do.

  The present invention includes an image forming apparatus having the above developing device.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 is provided on the upper portion of the image forming apparatus main body 12. A paper feeding device 18 is provided below the image forming apparatus main body 12.

  The discharge unit 16 includes an inclined unit 22 that is rotatable with respect to the image forming apparatus 12. The inclined portion 22 has a low discharge port portion, and is inclined so as to gradually increase toward the front surface direction (the right direction in FIG. 1). The discharge port portion is a lower end, and the higher tip is an upper end. The inclined portion 22 is supported by the image forming apparatus main body 12 so as to be rotatable about the lower end. As shown by a two-dot chain line in FIG. 1, when the inclined portion 22 is rotated upward and opened, an opening portion 24 is formed, and the process cartridge 40 can be attached and detached through the opening portion 24.

  The image forming means 14 is of, for example, an electrophotographic system, and includes an image carrier 26 made of a photosensitive member, a charging device 28 made of, for example, a charging roll that uniformly charges the image carrier 26, and a charging device 28. An optical writing device 30 for writing a latent image on the charged image carrier 26 with light, and a developing device 32 for visualizing the latent image of the image carrier 26 formed by the optical writing device 30 with a developer; The developing device 32 transfers a developer image to a sheet, for example, a transfer device 34 including a transfer roll, a cleaning device 36 including a blade for cleaning the developer remaining on the image carrier 26, and the transfer device 34 For example, a fixing device 38 including a pressure roll and a heating roll is used to fix the developer image on the paper to the paper. The optical writing device 30 is composed of, for example, a scanning type laser exposure device, and is arranged in the vicinity of the front surface (right side surface in FIG. 1) of the image forming apparatus main body 12 in parallel with the paper feeding cassette 20 of the paper feeding device 18. The image carrier 26 is exposed across. Further, the developing device 32 includes a developing roll 42 provided with a developing sleeve 60 (described later) facing the image carrier 26.

  The process cartridge 40 is obtained by integrating the image carrier 26, the charging device 28, the developing device 32, and the cleaning device 36. The process cartridge 40 is disposed immediately below the inclined portion 22 of the discharge portion 16 and is attached / detached via the opening portion 24 formed when the inclined portion 22 is opened as described above.

  In the image forming apparatus main body 12, for example, a resist roll 44 is disposed on the upstream side (lower side in FIG. 1) of the transfer device 34. The paper picked up by the pick-up roll 47 from the paper feed cassette 20 of the paper feeding device 18 and transported to the transport path 45 via the feed roll 49 and the retard roll 51 is temporarily stopped by the resist roll 44 and image formation is performed at a predetermined timing. An image is formed by being sent to the means 14 and is discharged to the discharge portion 16 by the discharge roll 46.

  However, in the case of duplex printing, it is returned to the reverse path. That is, the front of the discharge roll 46 is divided into two forks, and a switching claw 48 is provided at the divided portion, and an inversion path 50 is formed to return from the divided portion to the registration roll 44. The reversing path 50 is provided with transport rolls 52a to 52c. In the case of double-sided printing, the switching claw 48 is switched to the side that opens the reversing path 50, and the discharge roll 46 starts from the front end of the sheet. Thus, the discharge roll 46 is reversed, the paper is guided to the reverse path 50, and is discharged to the discharge portion 16 through the registration roll 44, the transfer device 34 and the image carrier 26 and the fixing device 38. .

Next, the developing device 32 according to an embodiment of the present invention will be described with reference to the drawings.
2 and 3 show the developing device 32 according to the first embodiment of the present invention. FIG. 3 is an enlarged view of a main part of FIG. The developing device 32 of this embodiment uses magnetic one-component toner.
The developing device 32 includes a toner transport mechanism 54 that transports toner, a toner storage unit 56 that stores toner transported by the toner transport mechanism 54, a development chamber 58 that performs development, and toner transported to the development chamber 58. And a developing roll 42 having a developing sleeve 60 for developing the image carrier 26, and a toner thinning device (thinning means) 62 for thinning the toner on the developing sleeve 60 are provided. Further, a toner history removing unit 62 is provided in a state of being pressed against the developing sleeve 60 on the downstream side of the developing position 64 and on the upstream side of the thinning device 62. The developing sleeve 60 is provided with a magnet (not shown) inside. The toner thinning device 62 is installed on the upstream side of the development position in order to thin the toner on the developing sleeve 60 before development.

  In the developing device 32, the toner is transported from the toner storage unit 56 to the developing chamber 58 by the toner transport mechanism 54. Next, the toner conveyed to the developing chamber 58 adheres onto the developing sleeve 60 due to electrostatic force, intermolecular force, and magnetic force generated by a magnet installed in the developing sleeve 60. The toner adhering to the developing sleeve 60 is thinned by the toner thinning device 62 and developed on the image carrier 26 at the development position 64.

  As described above, the developing device 32 includes a non-conductive toner history removing unit 66 that moves the residual toner pressed against the developing sleeve 60 to the downstream side of the developing position 64 and the upstream side of the toner thinning device 62. Is provided. The toner history removing unit 66 is supported by a support unit 70 fixed to the wall 68 of the developing chamber 58. The support portion 70 is made of, for example, an elastic body such as a thin leaf spring, and is formed over the entire axial length of the developing sleeve 60. The support portion 70 is bent obliquely, one end of the support portion 70 is fixed to the wall 68, and the other end extends to the developing sleeve 60 side. Further, as shown in FIG. 4, a toner passage hole 74 is formed in the support portion 70 in the vicinity of the toner history removing portion 66. The toner scraped off from the developing sleeve 60 by the toner history removing unit 66 through the toner passage hole 74 is collected in the developing chamber 58. Since the toner collected in the developing chamber 58 is stirred again with new toner in the developing chamber 58, the development history is removed.

  As shown in FIG. 3, when the developing roll 42 is not attached to the developing device 32, the support unit 70 is inclined to the wall 68 of the developing chamber 58 with the end on the toner history removing unit 66 side slightly inclined. The toner history removing unit 66 is attached to the end of the support unit 70 on the toner history removing unit 66 side. When the developing roll 42 is mounted, the toner history removing unit 66 is pushed downward, and the support unit 70 is elastically deformed so as to be horizontal. At this time, since the toner history removing unit 66 is supported by the support unit 70, the toner history removing unit 66 is biased upward, and the toner history removing unit 66 is uniformly pressed against the developing sleeve 60. Accordingly, the toner scraping action on the developing sleeve 60 can be improved by the uniform pressure contact of the toner history removing unit 66, and the toner adhesion amount on the developing sleeve 60 can be reduced.

  Further, the toner history removing unit 66 is non-conductive, has a hardness that can scrape off the toner on the developing sleeve 60 without damaging the developing sleeve 60, and has an uneven surface. For example, a felt material made of Teflon (registered trademark), a non-conductive foam material, or a non-conductive non-woven fabric can be used. In this embodiment, a Teflon (registered trademark) felt material is used as the toner history removing unit 66. The surface of the felt of Teflon (registered trademark) has irregularities, and the effect of changing the upper and lower layers of the toner on the developing sleeve 60 and the development portion and the non-development portion by the scattering (disturbing) action of the irregularities. A toner replacement effect can be obtained. In other words, the toner on the developing sleeve 60 after development is agitated by the toner history removing unit 66 to generate a history removing action.

  In this embodiment, as shown in detail in FIG. 3, the corner of the toner history removing unit 66 is pressed against the developing sleeve 60 to remove the toner developing history, but the portion pressed against the developing sleeve 60 has a corner. It may be other than the portion, and may be pressed in any position as long as the toner on the developing sleeve 60 can be moved to remove the development history.

  In this embodiment, the developing sleeve after the development by the toner history removing unit 66 is performed by three actions: a scraping action, a scattering action, and an agitating action of the toner after being scraped off by the toner passage hole 74 with a new toner. The residual toner on the developing sleeve 60 after development on the developing sleeve 60 can be moved on the surface of the developing sleeve 60 or scraped off from the developing sleeve 60, and the developing sleeve 60 can be mechanically operated by the toner history removing unit 66. The development history of the upper toner can be removed. Therefore, the development history of the toner on the developing sleeve 60 can be removed without using an electric means, and when forming a new thin layer toner, the developing sleeve 60 generated between the developing portion and the non-developing portion. The difference between the upper toner amount and the toner charge amount and the difference in the adhesion force of the developing sleeve 60 of the thinned toner are less likely to occur, so that the occurrence of the image density difference can be prevented.

Next, a second embodiment of the toner history removing unit 66 of the present invention will be described.
In this embodiment, a brush-like one shown in FIG. Also in this embodiment, as in the first embodiment, the toner history removing unit 66 has elasticity and is supported by the support unit 70 in which the toner passage hole 74 is formed. Therefore, the toner history removing unit 66 is urged upward, and the toner history removing unit 66 is uniformly pressed against the developing sleeve 60. Accordingly, the toner scraping action on the developing sleeve 60 can be improved by the uniform pressure contact of the toner history removing unit 66, and the toner adhesion amount on the developing sleeve 60 can be reduced.

  Further, since the toner history removing unit 66 of this embodiment has a brush shape, it has irregularities on its surface, and the upper and lower layers of toner on the developing sleeve 60 are scattered by the irregularity (disturbance) of the irregularities. A replacement effect and a toner replacement effect between the development part and the non-development part are obtained.

Next, a third embodiment of the toner history removing unit 66 of the present invention will be described.
In this embodiment, a comb-like one shown in FIG. Also in this embodiment, as in the first embodiment, the toner history removing unit 66 has elasticity and is supported by the support unit 70 in which the toner passage hole 74 is formed. Therefore, the toner history removing unit 66 is urged upward, and the toner history removing unit 66 is uniformly pressed against the developing sleeve 60. Accordingly, the toner scraping action on the developing sleeve 60 can be improved by the uniform pressure contact of the toner history removing unit 66, and the toner adhesion amount on the developing sleeve 60 can be reduced.

  Further, since the toner history removing unit 66 of this embodiment has a comb shape, the surface has irregularities, and the upper and lower layers of the toner on the developing sleeve 60 are scattered by the irregularity of the irregularities. A replacement effect and a toner replacement effect between the development part and the non-development part are obtained.

  As described above, according to the present invention, the development history of the toner remaining on the development sleeve after development can be removed without using electric means, and the development apparatus capable of improving the image failure and the image having the development device It can be used for a forming apparatus.

1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view illustrating an outline of a developing device according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the developing device according to the first embodiment of the present invention. 1 is a front perspective view illustrating an outline of a toner history removing device according to a first embodiment of the present invention. FIG. 6 is a front perspective view illustrating an outline of a toner history removing unit according to a second embodiment of the present invention. FIG. 10 is a front perspective view illustrating an outline of a toner history removing unit according to a third embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 26 Image carrier 32 Developing device 42 Developing roll 54 Toner transport mechanism 56 Toner storage portion 58 Developing chamber 60 Developing sleeve 62 Toner thinning device 64 Developing position 66 Toner history removing portion 68 Wall (of developing chamber) 70 Support part 74 Toner passage hole

Claims (6)

  In a developing device that uses a one-component toner, a developing sleeve that carries and rotates the toner, a thinning means that is on the upstream side of the developing position and thins the toner on the developing sleeve, and downstream of the developing position And a non-conductive toner history removing unit that moves the residual toner that is in pressure contact with the developing sleeve.   The developing device according to claim 1, wherein the toner is a magnetic one-component toner.   The developing device according to claim 1, wherein the toner history removing unit has an uneven surface.   4. The developing device according to claim 1, wherein the toner history removing unit is provided in an elastic member, and is pressed against the developing sleeve by an urging force of the elastic member. 5.   The developing device according to claim 4, wherein a toner passage hole is formed in the elastic member.   An image forming apparatus comprising the developing device according to claim 1.

Images