JP2009150983A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a toner from creeping in between the outer peripheral face of the end of the developing roller and a sealing member and creep-in toner from leaking from the end of a developing roller when providing the sealing member preventing toner leakage on both the ends of an axial direction of the developing roller in a developing device using the developing roller changed by a diameter from an axial center part to both the ends. <P>SOLUTION: The developing device holds the toner t on the outer peripheral face 4 of the rotating developing roller, and develops to be conveyed to a developing region opposed to an image carrier P. The developing device uses the developing roller changed by the diameter from the axial center part to both the ends, provides a required width of the same diameter part 4b being a constant diameter on both the axial ends of the developing roller when providing the sealing member 7 preventing toner leakage along the outer peripheral face of both the axial ends of the developing roller, and provides the sealing member along the outer peripheral face of the same diameter part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device used for developing an electrostatic latent image formed on an image carrier in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine of these, and in particular, a rotating developing device. In the developing device that holds the toner on the outer peripheral surface of the roller and transports it to the developing area facing the image carrier to perform development, a developing roller having a diameter changed from the central portion in the axial direction toward both ends, When a seal member for preventing toner leakage is provided along the outer peripheral surface of both end portions in the axial direction of the developing roller, the toner may enter between the outer peripheral surface of the end portion of the developing roller and the seal member. It is characterized in that it can appropriately prevent the toner that has entered from leaking from the end of the developing roller.

  In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a combination of these, various developing devices are used to develop an electrostatic latent image formed on an image carrier.

  As such a developing device, in addition to a two-component developing type developing device including a carrier and toner in a developer, a one-component developing type developing device that does not use a carrier is known.

  For example, a developing device as shown in FIG. 1 is used as the one-component developing type developing device.

  Here, in the developing device, the toner t accommodated in the apparatus main body 1 is sent to the toner supply roller 3 by the toner feeding member 2, and the toner supply roller 3 is pressed against the developing roller 4 in a state where the toner is supplied. The supply roller 3 is rotated so as to move in a direction opposite to the developing roller 4 at a portion facing the developing roller 4, and the toner t is supplied from the toner supply roller 3 to the developing roller 4.

  The toner t supplied in this manner is held on the outer peripheral surface of the developing roller 4, and the toner t is conveyed toward the image carrier P as the developing roller 4 rotates, and the main body of the apparatus. The regulating member 5 provided in 1 is brought into pressure contact with the outer circumferential surface of the developing roller 4 to regulate the amount of toner t held and conveyed on the outer circumferential surface of the developing roller 4 and the toner t. I try to charge it.

  The toner t thus regulated and charged by the regulating member 5 is guided to the developing region facing the image carrier P by the developing roller 4, and the toner t is formed on the image carrier P from the developing roller 4. The developed electrostatic latent image is supplied for development.

  Here, in such a developing device, the developing roller 4 is pressed toward the image carrier P by the toner supply roller 3, the regulating member 5 and the like. The roller shaft 4a is deformed so that the central portion in the axial direction of the developing roller 4 protrudes toward the image carrier P from both axial ends of the developing roller 4 attached to the apparatus main body 1 via a bearing (not shown). did.

  When the central portion in the axial direction of the developing roller 4 is deformed so as to protrude toward the image carrier P in this way, when the development is performed with the developing roller 4 in contact with the image carrier P, the image carrier is used. The central portion of the developing roller 4 protruding toward the body P is strongly pressed against the image carrier P, causing the image carrier P to be damaged or worn, and causing uneven density in the formed image. There was.

  Even when the development is performed with the developing roller 4 facing the image carrier P with a predetermined gap, the distance between the developing roller 4 and the image carrier P is such that the central portion and both end portions of the developing roller 4 are separated. Unlike the above, there is a problem that uneven density occurs in the formed image.

  For this reason, conventionally, as disclosed in Patent Document 1, a developing roller having a reverse crown shape whose diameter gradually increases from the central portion in the axial direction toward both ends, and the toner supply roller as described above. When the developing roller is pressed and deformed to the image carrier side by a regulating member or the like, the portion facing the image carrier becomes a straight line so that the distance between the developing roller and the image carrier is kept constant. What has been proposed is proposed.

  On the other hand, in the developing device as described above, in order to prevent the toner t supplied to the outer peripheral surface of the developing roller 4 from leaking out from both ends in the axial direction of the developing roller 4, in general, FIG. As shown in B), a seal member 6 for preventing toner leakage is provided along the outer peripheral surface of both end portions in the axial direction of the developing roller 4.

  Here, in the case where the developing roller 4 whose diameter gradually increases from the central portion in the axial direction toward both end portions as described above, as shown in FIG. 3, the outer periphery of both end portions in the axial direction of the developing roller 4 is used. When the seal member 6 for preventing toner leakage along the surface is provided, the diameter of the developing roller 4 increases from the central portion in the axial direction toward both ends, so that the outer periphery of the developing roller 4 at both axial ends. A gap s is generated between the surface and the seal member 6, and in particular, when the portion of the developing roller 4 facing the image carrier P is deformed to be linear, the side opposite to the portion facing the image carrier P The gap s between the outer peripheral surface of the developing roller 4 and the seal member 6 increases.

Then, the toner t enters the gap s between the outer peripheral surface of the developing roller 4 and the seal member 6, and the toner t that has deteriorated by entering the gap is returned to the apparatus main body 1 and used for development. The image to be formed is adversely affected, and the toner t is sequentially packed in the gap s between the outer peripheral surface of the developing roller 4 and the sealing member 6 in this way, and the sealing member 6 is connected to the developing roller 4. There is a problem that the toner t leaks from both ends of the developing roller 4 in the axial direction.
JP-A-6-258933

  The present invention relates to a developing device in which toner is held on the outer peripheral surface of a rotating developing roller and transported to a developing region facing an image carrier to perform development, and the diameter changes from the center in the axial direction toward both ends. When the developing roller is used and a seal member for preventing toner leakage is provided along the outer peripheral surface of both end portions in the axial direction of the developing roller, the toner enters between the end portion of the developing roller and the seal member. It is an object of the present invention to appropriately prevent the toner that has deteriorated in the above-described manner or leaked from the end portion of the developing roller.

  In the present invention, in order to solve the above-described problems, in a developing device for developing by holding toner on the outer peripheral surface of a rotating developing roller and transporting the toner to a developing region facing the image carrier. When using a developing roller having a diameter changed from the central portion in the axial direction toward both end portions, and providing a seal member for preventing toner leakage along the outer peripheral surface of both end portions in the axial direction of the developing roller, the above developing roller The same diameter portion having a constant diameter is provided at both ends in the axial direction with a required width, and the sealing member is provided along the outer peripheral surface of the same diameter portion.

  Here, as the developing roller, a roller having a reverse crown shape in which the diameter gradually increases from the central portion in the axial direction toward both end portions is used, but conversely, the diameter is the central portion in the axial direction. It may be a crown shape that gradually decreases from the end toward both ends.

  When the toner is held on the outer peripheral surface of the developing roller as described above and transported to the developing area facing the image carrier to perform appropriate development, the developing roller is pressed by the pressing member. Therefore, the portion of the developing roller facing the image carrier is linear, and particularly when the developing roller is composed of a metal roller, the developing roller contacts the image carrier. In order to prevent the image carrier from being damaged, the developing roller is made to face the image carrier at a predetermined interval.

  In the developing device of the present invention, as described above, the developing roller having a diameter changed from the central portion in the axial direction toward both end portions is used, and toner leakage is prevented from occurring on the outer peripheral surfaces of both end portions in the axial direction of the developing roller. In providing the seal member, the same diameter portion having a constant diameter is provided at both end portions in the axial direction of the developing roller, and the seal member is provided in the same diameter portion. The seal member is in close contact with the outer peripheral surface of the same diameter portion at both end portions in the axial direction of the developing roller.

  As a result, in the developing device of the present invention, even when the developing roller whose diameter is changed from the central portion in the axial direction toward both ends as described above, the shaft of the seal member and the developing roller is used as in the conventional case. The toner enters the gap between the outer peripheral surfaces at both ends in the direction and deteriorates, or the toner is sequentially packed into the gap between the outer peripheral surfaces at the both ends in the axial direction of the developing roller and the seal member. In addition, it does not leak from both ends in the axial direction of the developing roller.

  Next, a developing device according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Note that the developing device according to the present invention is not limited to the one shown in the following embodiment, and can be appropriately changed and implemented without changing the gist thereof.

  Also in the developing apparatus of this embodiment, as shown in FIG. 1, the toner t accommodated in the apparatus main body 1 is sent to the toner supply roller 3 formed into a roller shape by the toner feeding member 2, and this toner supply is performed. In a state where the roller 3 is pressed against the developing roller 4, the toner supply roller 3 is rotated so as to move in a direction opposite to the developing roller 4 at a portion facing the developing roller 4. Is supplied to the developing roller 4.

  The toner t supplied in this manner is held on the outer peripheral surface of the developing roller 4, and the toner t is conveyed toward the image carrier P as the developing roller 4 rotates, and the main body of the apparatus. The regulating member 5 provided in 1 is brought into pressure contact with the outer circumferential surface of the developing roller 4 to regulate the amount of toner t held and conveyed on the outer circumferential surface of the developing roller 4 and the toner t. I try to charge it.

  Next, the toner t regulated and charged by the regulating member 5 is guided to the developing area facing the image carrier P by the developing roller 4, and the toner t is formed on the image carrier P from the developing roller 4. The developed electrostatic latent image is supplied for development.

  Here, also in the developing device of this embodiment, as described above, the developing roller 4 is pressed and deformed by the toner supply roller 3, the regulating member 5, and the like toward the image carrier P and faces the image carrier P. In this portion, the central portion in the axial direction of the developing roller 4 protrudes toward the image carrier P.

  For this reason, in the developing device of this embodiment, the developing roller 4 is constituted by a metal roller whose outer peripheral surface is roughened by blasting or the like, and as shown in FIG. A reverse crown shape having a diameter gradually increasing from both ends toward the both ends, and having the same diameter portion 4b having a constant diameter at both end portions in the axial direction is used.

  As shown in FIG. 5, a seal member 6 for preventing toner leakage is provided along the outer peripheral surface of the same diameter portion 4b at the same diameter portion 4b at both axial end portions of the developing roller 4 described above. I have to. In this way, the sealing member 6 is not in close contact with the outer peripheral surface of the same-diameter portion 4b of the developing roller 4, and no gap is generated.

  Here, in the developing device of this embodiment, when developing with the developing roller 4 facing the image carrier P with a required interval therebetween, as shown in FIG. In the state where the seal member 6 is provided so as to be along the outer peripheral surface of the same diameter portion 4 b at both ends in the direction, the diameter of the developing roller 4 is larger than the diameter of both ends of the developing roller 4. The roller member 7 is attached, and the roller member 7 is brought into contact with the outer peripheral surface of the image carrier P so that the developing roller 4 faces the image carrier P with a predetermined interval.

  In the developing device according to this embodiment, the developing roller 4 is pressed toward the image carrier P by the toner supply roller 3 and the regulating member 5 as described above, and the central portion in the axial direction of the developing roller 4 is the image. When the developing roller 4 is deformed so as to protrude toward the carrier P side, the developing roller 4 has an inverse crown shape in which the diameter gradually increases from the central portion in the axial direction toward both ends as described above. As shown in FIG. 6, the portion of the developing roller 4 facing the image carrier P is linear, and the distance d between the portions of the developing roller 4 and image carrier P facing each other is kept constant. .

  For this reason, the toner t is appropriately supplied from the developing roller 4 to the electrostatic latent image formed on the image carrier P, and unevenness of density or the like is prevented from occurring in the formed image.

  Further, in the developing device of this embodiment, since the seal member 6 for preventing toner leakage is provided along the outer peripheral surface of the same diameter portion 4b at both axial end portions of the developing roller 4, as described above. Even when developing, the seal member 6 is maintained in close contact with the outer peripheral surface of the same-diameter portion 4b of the developing roller 4, and the seal member 6 and the outer peripheral surfaces of both end portions in the axial direction of the developing roller 4 are maintained. The toner t is prevented from entering between the seal member 6 and the toner t between the seal member 6 and the outer peripheral surfaces of both end portions of the developing roller 4 in the axial direction and deteriorates or leaks from both end portions of the developing roller 4 in the axial direction. It is prevented from taking out.

  In the developing device of this embodiment, development is performed with the developing roller 4 facing the image carrier P with a predetermined interval, but development is performed by bringing the developing roller 4 into contact with the image carrier P. Of course, the same effect can be obtained in the developing apparatus.

  Next, an example of an image forming apparatus using the developing device as described above will be described with reference to FIG.

  In this image forming apparatus, four developing devices 10A to 10D as described above are used, and toners of different colors of yellow, magenta, cyan and black are accommodated in the four developing devices 10A to 10D. Yes.

  The four developing devices 10A to 10D are held by a rotating holder 21, and the holder 21 is rotated to sequentially change the positions of the developing devices 10A to 10D. Development is performed by sequentially leading to a position facing the body P.

  When a color image is formed by this color image forming apparatus, for example, first, the developing roller 4 in the first developing apparatus 10A containing yellow toner is positioned so as to face the image carrier P, and the image is formed. The surface of the image carrier P is uniformly charged by the charging device 22 by rotating the carrier P, and the image carrier P thus charged is exposed according to the image signal by the exposure device 23. Then, an electrostatic latent image is formed on the surface of the image carrier P.

  Next, yellow toner is transferred from the developing roller 4 to the image carrier P in the developing region where the image carrier P on which the electrostatic latent image is formed in this way and the developing roller 4 in the first developing device 10A face each other. A yellow toner image corresponding to the electrostatic latent image is formed on the image carrier P by supplying the formed electrostatic latent image portion.

  Then, the yellow toner image formed on the image carrier P in this way is transferred to an endless belt-like intermediate transfer member 24 that is stretched over the image carrier P.

  Thereafter, the holder 21 is rotated, and then the developing roller 4 in the second developing device 10B containing magenta toner is positioned so as to face the image carrier P, and the first In the same manner as in the developing device 10A, a magenta toner image is formed on the surface of the image carrier P, and this magenta toner image is transferred to the intermediate transfer member 24 to which the yellow toner image has been transferred. Further, the same operation is performed to form a cyan toner image on the surface of the image carrier P by the third developing device 10C containing cyan toner, and this cyan toner image is formed into the intermediate toner image. After being transferred to the transfer member 24, a black toner image is formed on the surface of the image carrier P by the fourth developing device 10D containing black toner, and this black toner image is transferred to the intermediate transfer member 24 described above. Let this be transcribed Uni yellow on the intermediate transfer member 24, magenta, cyan colors, by transferring the toner images of black full color.

  The recording sheet 25 set in the lower part of the color image forming apparatus is guided to a portion where the intermediate transfer member 24 and the transfer roller 27 face each other by the feed roller 26, and a full-color toner image formed on the intermediate transfer member 24. Is transferred onto the recording sheet 25, and the full-color toner image thus transferred onto the recording sheet 25 is fixed on the recording sheet 25 by the fixing device 28 and discharged.

  The image forming apparatus using the developing device of the present invention is not limited to the above, and may be a monochrome image forming apparatus or a tandem color image forming apparatus.

It is a schematic explanatory drawing of the conventional example and the image development apparatus of one Embodiment of this invention. In the developing device of the conventional example, a schematic front view and a schematic side view showing a state in which seal members for preventing toner leakage are provided along the outer peripheral surfaces of both end portions in the axial direction of the developing roller. In a conventional developing device, a developing roller having a diameter that gradually increases from the central portion in the axial direction toward both ends, and a seal member that prevents toner leakage along the outer peripheral surface of the axial end portion of the developing roller is provided. It is the partial explanatory view which showed the state provided. It is the schematic front view which showed the developing roller used in the developing device of one Embodiment of this invention. FIG. 4 is a partial explanatory view showing a state in which a seal member for preventing toner leakage is provided along the outer peripheral surface of the same diameter portion at the end portion in the axial direction of the developing roller in the developing device of the embodiment. In the developing device of the above-described embodiment, a state in which a seal member for preventing toner leakage is provided at both ends in the axial direction of the developing roller and the developing roller is opposed to the image carrier is shown. It is a schematic explanatory drawing. 1 is a schematic explanatory view showing an example of an image forming apparatus using a developing device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Toner feed member 3 Toner supply roller 4 Developing roller 4a Roller shaft 4b Same diameter part 5 Restriction member 6 Sealing member 7 Roller member 10A-10D Developing device 21 Holder 22 Charging device 23 Exposure device 24 Intermediate transfer body 25 Recording sheet 26 Feed roller 27 Transfer roller 28 Fixing device P Image carrier t Toner

Claims (4)

  In a developing device that holds toner on the outer peripheral surface of a rotating developing roller and transports it to a developing area facing the image carrier to perform development, a developing roller having a diameter that changes from the center in the axial direction toward both ends. When the seal member for preventing toner leakage is provided along the outer peripheral surface of both end portions in the axial direction of the developing roller, the same diameter portion having a constant diameter is provided at both end portions in the axial direction of the developing roller. A developing device comprising: a sealing member provided along an outer peripheral surface of the same diameter portion.   2. The developing device according to claim 1, wherein the diameter of the developing roller gradually increases from a central portion in the axial direction toward both end portions.   3. The developing device according to claim 1, wherein a pressing member that presses the developing roller is provided, and the developing roller is deformed by the pressing by the pressing member and faces the image carrier. The developing device is characterized in that the portion of the straight line is linear.   4. The developing device according to claim 1, wherein the developing roller is formed of a metal roller, and the developing roller is opposed to the image carrier at a predetermined interval. A developing device.

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