JP2007058023A - Developing device and electrophotographic device equipped with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device which can securely prevent a developer from entering a bearing member and has superior durability. <P>SOLUTION: The developing device is provided with the bearing member (64) and a developer entry preventive member (66) on a rotary shaft (63) so that mutually opposite flanks of the bearing member (64) and developer entry preventive member (66) and an outer peripheral surface of the rotary shaft (63) form an annularly-sectioned space (a), and further equipped with a blast hole (67) which communicates with the annular space to supply air to the annular space and an exhaust hole (68) which communicates with the annular space to discharge the air in the annular space. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device and an electrophotographic apparatus including the developing device, and more particularly, to an improvement of a developing device having a mechanism for preventing a developer from entering a bearing member that supports a developer conveying member. Is.

  A developing roller used to form a visible image on a photosensitive member by supplying a powder developer to the photosensitive member holding an electrostatic latent image in a developing device of an electrophotographic apparatus such as a printer or a copying machine. And a plurality of developer conveying members such as a conveying roller or conveying screw used for conveying the developer to the developing roller, and an agitation paddle used for agitating and mixing the developer contained in the developing device. Is used.

  When the developer conveying member is driven to rotate and the developer contained in the developing device is caused to flow, the developer enters the bearing member (bearing) that supports the rotation shaft of the developer conveying member, and the inside of the bearing member Due to the frictional heat, the invading developer melts and adheres, and the rotation of the rotating shaft becomes abnormal.As a result, the stirring and mixing of the developer and the transport amount are not stable, and an image with uneven density is printed, Alternatively, the rotating shaft may be locked due to melting and fixing of the invading developer, and printing may be impossible.

  Various mechanisms have been proposed for preventing the intrusion of the developer into the bearing member. The mechanism is made of a felt containing a rubber seal member or grease on the rotating shaft between the bearing member and the developer conveying member. It is known to interpose a sealing member.

  In addition, a configuration has been proposed in which a discharge opening is provided in the bearing housing so that the developer that has entered the bearing housing holding the bearing member can be discharged from the bearing housing.

JP 2000-147904 A

  In order to perform continuous printing for several hours to several tens of hours, or to achieve high-speed transport of developer in the developing device as the printing speed of the electrophotographic apparatus increases, a rubber seal is used for durability. It becomes difficult to prevent the intrusion of the developer only with the member or the grease-containing felt seal member.

  In particular, when the developer to be used is a two-component developer composed of toner and carrier, the carrier particles that have entered the developer intrusion prevention member and the bearing member act as an abrasive, which accelerates wear deterioration. The problem also occurs.

  In addition, as in Patent Document 1, the developer that has entered may not be completely discharged from the bearing housing by simply dropping it from the discharge port of the bearing housing or sweeping it out with a brush, and remains in the bearing housing. The problem of the melted and fixed developer still remains.

  The present invention provides a developer conveying member that is rotatably supported and conveys a developer, a bearing member that supports an end portion of a rotating shaft of the developer conveying member, and an axis of the rotating shaft adjacent to the bearing member. And a developer intrusion prevention member that prevents the intrusion of the developer into the bearing member, and the rotating shaft and the side surfaces of the bearing member and the developer intrusion prevention member that face each other. The bearing member and the developer intrusion prevention member are provided on the rotating shaft so that the outer peripheral surface of the outer peripheral surface forms a space having an annular cross section, and air is supplied to the annular space by communicating with the annular space. And an exhaust port that communicates with the annular space and exhausts the air in the annular space.

  According to the present invention, the developer that has passed through the developer intrusion prevention member and entered the annular space is discharged out of the annular space using the air flowing through the annular space. It is possible to provide a developing device that can reliably prevent entry of the agent and has excellent durability.

  Further, by realizing the developing device, an electrophotographic apparatus capable of maintaining printing with stable image quality for a long time can be provided.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  First, an overall configuration of an electrophotographic apparatus to which the present invention is applied will be described with reference to FIG. 3 by exemplifying a laser beam printer that performs printing on continuous paper.

  In FIG. 3, reference numeral 1 denotes a laser beam printer. The photosensitive drum 21 starts to rotate in the direction of the arrow based on a printing operation start signal from the controller 22. The photosensitive drum 21 rotates at a speed corresponding to the printing speed of the laser beam printer 1 and continues to rotate until the printing operation is completed. When the photosensitive drum 21 starts to rotate, a high voltage is applied to the corona charger 2 and, for example, positive charges are uniformly charged on the surface of the photosensitive drum 21.

  The rotary polygon mirror 3 starts rotating as soon as the laser beam printer 1 is turned on, and maintains constant speed rotation with high accuracy while the power is turned on. The laser beam output from the semiconductor laser 4 is reflected by the rotary polygon mirror 3 and irradiated while scanning the photosensitive drum 21 through the fθ lens 5.

  When character data or graphic data converted into a dot image is sent from the controller 22 to the laser beam printer 1 as a laser beam on / off signal, the surface of the photosensitive drum 21 is irradiated with the laser beam and the non-irradiated portion. Are formed, and a so-called electrostatic latent image is formed.

  When the photosensitive drum area holding the electrostatic latent image reaches a position facing the developing device 6, developer is supplied to the electrostatic latent image by the developing rollers 6a, 6b, and 6c, and the photosensitive drum 21 is irradiated with a laser beam. For example, a positively charged developer adheres to the portion where the upper charge disappears, and a visible image is formed on the photosensitive drum 21. Reference numeral 6d denotes a conveyance roller, which is a conveyance roller for pumping up the developer contained in the developing device 6 and supplying and feeding the developer to the development roller 6b.

  The continuous paper 7 stored in the paper hopper 11 is synchronized with the timing at which the visible image of the print data formed on the photosensitive drum 21 reaches the transfer position by the paper transport tractor 8 and the transfer drum. 10 is conveyed toward the middle.

  The visible image formed on the photosensitive drum 21 is sucked onto the sheet 7 by the action of the transfer unit 10 that applies a charge having a polarity opposite to that of the toner image on the back side of the sheet 7.

  In this way, the paper 7 set in the paper hopper 11 is transported to the fixing device 12 through the paper transport tractor 8, the transfer device 10, the paper transport tractor 9, and the buffer plate 24. The paper 7 that has reached the fixing device 12 is preheated by the preheater 13 and then heated and pressed by a nip formed by a pair of fixing rollers including a heating roller 14 having a heater lamp 25 and a pressure roller 15. The toner image is melted and fixed on the paper 7 while being nipped and conveyed.

  The paper 7 sent out by the heating roller 14 and the pressure roller 15 is sent out to the stacker table 19 side by the paper feed roller 16 and is alternately folded along the perforation by the swinging motion of the swing fin 17. Further, while the folded state is adjusted by the rotating paddle 18, they are stacked on the stacker table 19. The area that has passed the transfer position of the photosensitive drum 21 is cleaned by the cleaning device 20 and is prepared for the next printing operation.

  In FIG. 3, reference numeral 23 denotes a display screen for displaying information based on the state of the laser beam printer 1 during the printing operation. The buffer plate 24 is for absorbing slack or tension generated on the paper 7 when a paper transport speed difference occurs between the paper transport tractor 9 and the fixing rollers 14 and 15. Reference numeral 26 denotes a web member provided so as to be able to come into contact with the surface of the heating roller 14 and to be wound, for cleaning the surface of the heating roller 14 and applying a release agent to the surface of the heating roller 14. Is.

  Next, the configuration of the developing device of the present invention will be described with reference to FIGS. 1 is a cross-sectional view in the axial direction of a bearing portion of a developer conveying member, and FIG. 2 is a cross-sectional view taken along the line AA in FIG.

  In FIG. 1, reference numeral 61 denotes a bottom plate, and reference numeral 62 denotes a side plate. The bottom plate 61 and the side plate 62 constitute a developer container that accommodates the developer D, and the developer is conveyed inside the developer container that accommodates the developer D. Members (this example will be described based on an example applied to the conveyance roller 6d) are arranged.

  A bearing 64 serving as a bearing member is press-fitted to the end of the rotation shaft 63 of the transport roller 6d. The transport roller 6d is attached to the side plate 62 via a housing 65 fitted to the outer periphery of the bearing 64 and the bearing 64. It has been.

  Further, a developer intrusion preventing member 66 for preventing the developer D from entering the bearing 64 is provided on the axis of the rotating shaft 63 next to (inner side) the bearing 64. 66 is provided to seal a gap formed between the outer peripheral surface of the rotating shaft 63 and the inner peripheral surface of the housing 65.

  As shown in the drawing, a slight gap is provided between the bearing 64 and the developer intrusion prevention member 66, the side surfaces of the bearing 64 and the developer intrusion prevention member 66 facing each other, and the outer peripheral surface of the rotating shaft 63. The bearing 64 and the developer intrusion prevention member 66 are supported by the housing 65 such that the space a constitutes the space a. As shown in FIG. 2, the space a has an annular cross section around the rotation shaft 63. Also, the housing 65 is provided with a blower port 67 that communicates with the space a and supplies air to the space a, and an exhaust port 68 that communicates with the space a and discharges air within the space a. The air flow in the direction of the arrow can be formed.

  An air blower (not shown) is connected to the air outlet 67, and air is blown into the space a by operating the air blower constantly or only for a specific period set in advance.

  Further, it is advantageous to provide the exhaust port 68 so as to communicate with the inside of the developing container as shown in the figure, in order to prevent the outside of the developing container and the surroundings of the bearing member from being damaged. If it is not preferable to return the developer to the developing container, a recovery unit (not shown) may be provided outside the developing container and discharged there.

  In the above configuration, even if the developer D rubs through the developer intrusion preventing member 66 and enters the space a, the developer D flows into the exhaust port 68 by the air from the air blowing port 67. Since it is guided and discharged, the developer D does not stay in the space a.

  Further, since the bearing 65 can be simultaneously cooled by the blown air, it is possible to prevent the developer D that has entered the space a from melting.

It is an axial sectional view of a bearing portion of a developer conveying member. It is AA arrow sectional drawing of FIG. 1 is an overall configuration diagram of an electrophotographic apparatus.

Explanation of symbols

6d transport roller (developer transport member)
61 Bottom plate 62 Side plate 63 Rotating shaft 64 Bearing (Bearing member)
65 Housing 66 Developer Intrusion Prevention Member 67 Blower Port 68 Exhaust Port a Space

Claims (4)

A developer transport member that is rotatably supported and transports the developer, a bearing member that supports a rotating shaft end of the developer transport member, and is disposed next to the bearing member on the shaft of the rotating shaft; In a developing device comprising a developer intrusion preventing member that prevents the developer from entering the bearing member,
The bearing member and the developer intrusion prevention member are arranged so that a side surface of the bearing member and the developer intrusion prevention member facing each other and an outer peripheral surface of the rotary shaft form a space having an annular cross section. A blower port that is provided on the rotary shaft and communicates with the annular space to supply air to the annular space, and an exhaust port that communicates with the annular space and discharges the air in the annular space. A developing device comprising:   2. The developing device according to claim 1, wherein a blower is connected to the blower port.   2. The developing device according to claim 1, wherein the exhaust port is provided in communication with the inside of the developing device. An electrophotographic apparatus comprising the developing device according to claim 1.

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