JP2005338313A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus equipped with an intermediate transfer unit reduced in the number of parts while good transfer is performed. <P>SOLUTION: The image forming apparatus is equipped with the belt-like intermediate transfer member. The belt-like intermediate transfer member is connected to an area which is a grounding potential of a power source at ≥2 points through at least supports at ≥2 points having a conductive resin or conductive elastic body on the surfaces. The belt-like intermediate transfer member constitutes a unit together with the supports. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to electrical connection of an intermediate transfer member of an electrophotographic image forming apparatus.

  In an electrophotographic image forming apparatus, an intermediate transfer member is used for a first transfer transferred from a photoreceptor and a second transfer transferred to a transfer member such as paper. At this time, since the voltage used for the first transfer is different from the voltage used for the second transfer, the support supported by the first transfer portion and the support supported by the second transfer portion are configured with independent potentials. It was. An example of such a prior art is described in Patent Document 1.

JP 2002-328535 A (Description of paragraphs (0058) to (0062))

  As shown in FIG. 3, the conventional image forming apparatus includes a first transfer side support 23 and a second transfer side support 25 contained in an intermediate transfer body 28, and is electrically insulated and independent. doing. The first transfer is performed by a first transfer voltage formed by the high voltage power supply circuit 24 between the photoconductor 22 and the first support 23. The second transfer is performed by a second transfer voltage formed by a high-voltage power supply circuit 27 between the transfer roller 26 serving as a transfer unit and the second support 25. For this reason, each transfer voltage is applied with an independent power source and electrode.

  Thus, in order to supply different voltages to the first transfer portion and the second transfer portion, two electrodes are connected to the intermediate transfer member, and good contact between these two electrodes is necessary. In addition, there is a potential gradient inside the intermediate transfer member, which may reduce transfer efficiency and image quality.

  An object of the present invention is to provide an image forming apparatus in which an intermediate transfer body is basically set to the same potential and the potential gradient is eliminated, thereby obtaining good image quality and a single system of electrodes used for the intermediate transfer body. There is.

  The image forming apparatus of the present invention includes a belt-like intermediate transfer member, and the belt-like intermediate transfer member is held at a predetermined potential via at least two or more supports. Have a conductive resin or a conductive elastic body. The at least two supports are electrically conductive and are grounded. This is connected to the part which is the ground potential of the power supply. Preferably, it is connected to the ground potential of the power supply at at least two locations. The intermediate transfer member is configured as a unit together with the support.

  According to the present invention, the intermediate transfer member is set to the same potential, and the potential gradient is eliminated, thereby obtaining good image quality and high reliability with a reduced number of parts by providing one electrode for the intermediate transfer member. An image forming apparatus can be provided.

  Hereinafter, details of the present invention will be described with reference to the drawings.

  The image forming apparatus of the present embodiment will be described with reference to FIG. A multi-color image forming apparatus that superimposes colors using a plurality of color toners has a plurality of developing devices 4 that store toners that are colored particles, and the belt-like photoreceptor 1 is charged by the charger 2. Then, an electrostatic latent image is formed by the exposure device 3, toner is attached to the electrostatic latent image on the belt-shaped photosensitive member 1 by the developing device 4 to form a toner image, and the toner image on the belt-shaped photosensitive member 1 is formed. The toner image is transferred to the intermediate transfer member 5 (first transfer), and the printing medium stored in the storage container 8 is supplied by the paper feeding unit 9 between the transfer unit 10 and the intermediate transfer member to transfer the toner image. (Second transfer) or a toner image is directly transferred from the photosensitive member to the printing medium (second transfer), and the toner is fixed by the fixing device 11 to obtain a printed image. The toner remaining on the intermediate transfer member 8 is cleaned by the cleaner 12 and the next printing is performed. The image forming apparatus applies a potential difference using a circuit between the photosensitive member and the intermediate transfer member in order to perform the first transfer. Similarly, in the second transfer, a potential difference is given to components such as the intermediate transfer member and the transfer roller.

  The image forming apparatus shown in FIG. 1 uses a belt-like photosensitive member and a belt-like intermediate transfer member, creates a toner image on the photosensitive member for each color, transfers the toner image to the intermediate transfer member, and transfers a plurality of color toner images to the intermediate transfer member. Is a multi-rotation type multi-color image forming apparatus that obtains a multi-color print image on top of each other. The first transfer is performed between the belt-like photosensitive member 1 and the intermediate transfer member 5, and a printing medium such as paper or an OHP film is moved between the intermediate transfer member 5 and the transfer roller 10 serving as a transfer unit to move the second transfer member 10. Transcription.

  In the image forming apparatus of the present embodiment, the transfer belt 29 is supported by a metal first roller 30 and a metal second roller 31 as shown in FIG. The intermediate transfer unit is supported by a frame 41.

  Further, as shown by an arrow A in FIG. 1, the intermediate transfer body unit has a structure in which the intermediate transfer body 6 can be detached from the fixing position of the intermediate transfer body in the direction A where the transfer roller as the transfer means 10 is located. When the surface of the intermediate transfer body 6 is damaged by dust or scratches, the intermediate transfer body unit can be easily attached and detached and replaced.

  Next, details of the intermediate transfer unit of this embodiment will be described with reference to FIG. As shown in FIG. 2, in the intermediate transfer unit of this embodiment, the first roller 30 and the second roller 31 are electrically connected. As a result, the electrodes that have been supplied with power to the respective rollers can be integrated into one system so that the number of parts can be reduced and the reliability can be increased. In this embodiment, since the transfer belts supported by the first roller and the second roller are basically at the same potential, image defects such as toner scattering caused by the potential difference can be reduced, and in addition, transfer efficiency can be improved. Decrease can be avoided.

  In this embodiment, the conductive roller contained in the first roller 30 and the second roller 31 of the intermediate transfer member is connected to a common potential 45, and the photosensitive member 42 supplies the first transfer voltage. The transfer roller 43 is connected to one transfer power supply 46 and a second transfer power supply 47 that supplies a second transfer voltage. The electrical connection between the first roller 30 and the second roller 31 uses a conductive side plate 44 that supports each shaft. The positional relationship will be described with reference to FIG. 4. The side plates 19 and 20 supporting the shaft 17 of the first roller 30 supporting the transfer belt 16 and the shaft 18 of the second roller 31 are electrically connected to each shaft. These are connected to a power source 21 arranged on the side.

  A method of using electrodes as described above is generally used for connection from the intermediate transfer unit to the power source. In this embodiment, as the electrode, a spring or a conductive elastic body whose surface is covered with a conductive resin is used so as not to damage the surface of the intermediate transfer body during manufacturing and assembly. Specifically, a member such as a leaf spring is preferable because it is easy to handle.

  As another method, conduction may be achieved by using a fixing member for fixing the intermediate transfer member unit. For example, when the conductive side plate 44 supporting the shaft is tightened with a screw or the like, the tightening destination may be a metal or a conductive resin attached to a main body frame such as a power supply base. For example, as shown in FIG. 5, when the first roller 35 and the second roller 36 of the intermediate transfer body unit are inserted into the guide 40 provided on the main body frame, the conductive fixing member 37 and the conductive member 37 are electrically conductive. The screw 38 is used to fix the frame 33 from the direction of the arrow D. As a result, the intermediate transfer unit is electrically connected to the power supply 34 attached to the frame via the screw 38.

  Further, in this embodiment, since the roller included in the intermediate transfer member is connected to the ground potential, the intermediate transfer member occupying a large volume in the image forming apparatus can be set to the ground potential. The voltage stability can be improved because the two power supply circuits for supplying the voltage can be configured from the ground potential without floating.

  At this time, in order to make the ground potential, it is necessary to connect to the power source of the image forming apparatus, and it is preferable to connect directly to a grounding component such as a power source base surrounding the power source. I do not care. Connection to the power supply base is performed by pressing the conductive material into contact with the power supply base or fixing by screw tightening. Furthermore, it is preferable that the electrical connection is made at a plurality of points of two or more points.

  Next, the configuration of the conductive rollers such as the first roller 35 and the second roller 36 in this embodiment and the connection method to the grounding component of the power source will be described. The case where the first roller and the second roller are metal rollers has been described. However, these rollers may be rollers using conductive resin, as long as the same potential can be applied to the belt-shaped intermediate transfer member. Good. Further, in order to secure the nip of the transfer portion, it may be composed of a conductive elastic body. Here, as the conductive elastic body, a conductive rubber provided on the surface layer, a conductive sponge, a metal film, a metal mesh encapsulated sponge, or the like can be used.

  The conductive roller has a first structure in which a surface layer portion that contacts the transfer belt and a shaft serving as a shaft rotate together, and a second structure in which the surface layer portion rotates and the shaft portion is fixed without rotating. There is a configuration.

  In the conductive roller of the first configuration, the conductive member in contact with the shaft, for example, an electrode, a ball bearing, a conductive bearing or the like is used to electrically contact the frame of the intermediate transfer body unit or the main body frame, and The roller in the intermediate transfer body is brought into conduction to the power source by bringing it into contact with the ground potential of the power source such as the power base. Here, a conductive resin or a conductive elastic body may be used as the material of the electrode and the conductive bearing.

  In the second configuration, the shaft does not rotate, and conduction is achieved using an electrode, a ball bearing, a conductive bearing, or the like between the roller surface layer portion and the shaft. The shaft is brought into electrical contact with the frame of the intermediate transfer body unit or the main body frame as it is, and is further brought into contact with a portion of the power supply base such as a power supply ground potential, and the roller of the intermediate transfer body is made conductive to the power supply. Also in this case, a conductive resin or a conductive elastic body may be used as a material for the electrode or the conductive bearing.

  The support in the intermediate transfer body may be a plate-like member using a conductive resin or a conductive elastic body. If it is a shape that fits the nip shape and that takes into account rubbing, the same potential can be applied to the transfer belt, and the rotation of the transfer belt is not suppressed. With this configuration that does not, the number of parts can be reduced.

  The intermediate transfer member unit of this embodiment shown in FIG. 4 has a belt-like intermediate transfer member 16, and this belt-like intermediate transfer member 16 (about 380 mm per round) is supported by a plurality of rollers. The plurality of rollers are composed of rollers having different sizes, and an intermediate transfer member belt supported by a large roller 17 (about φ104 mm) having a large curvature abuts on the photosensitive member, and the other roller 18 (about φ30 mm). Opposite to the transfer means 10. At both ends of the intermediate transfer body unit, there are U-shaped alignment members 20 (about R16 mm), and bearings (about 16 mm) that support the transfer means 10 (about 20 mm) at the opening of the image forming apparatus guide. It becomes a member and aligns with the alignment member. The transfer unit 10 is attached to the opening of the image forming apparatus, and the intermediate transfer body unit can be taken out by opening a door that covers the opening. At this time, the intermediate transfer body unit can be attached and detached while being supported by rail members provided on both sides.

  As shown in FIG. 5, the intermediate transfer member unit of the present embodiment is configured to support at least two points on one side, and has a large roller shaft (about φ8 mm) for contacting the photosensitive member, the transfer means, A small roller shaft (about φ6 mm) for contact is supported by two shafts, and a rail is provided between the two shafts. Other parts may be used to support the intermediate transfer unit. The fixing means is configured to fix the shaft of the large roller and is screwed to the main body frame near the opening. In order to more easily replace the intermediate transfer body unit, it may be fixed with a lever using a cam mechanism or the like.

  The intermediate transfer body unit may include a tension roller 32 that maintains the tension of the transfer belt. Further, in order to clean the belt, a part that contacts the belt may be provided. The tension roller 32 may be a conductive roller made of a conductive material. When the tension roller 32 is electrically connected to the intermediate transfer member frame, no extra charge is superimposed on the tension roller 32 and toner scattering or the like occurs. Can be reduced.

It is explanatory drawing of the image forming apparatus of an Example. FIG. 3 is an explanatory diagram of an intermediate transfer body unit of an example. It is explanatory drawing of the intermediate transfer body unit of a prior art. FIG. 3 is an explanatory diagram of an external appearance of an intermediate transfer body unit of an example. It is explanatory drawing of the method of fixing the intermediate transfer body unit of an Example with a board.

Explanation of symbols

1, 22, 42, photoconductor, 2, charger, 3, exposure device, 4, developing device, 5, 41, intermediate transfer body unit, 6, 17, 30, first roller, 7, 18, 31,. Second roller, 8 ... storage container, 9 ... paper feeding device, 10 ... transfer means, 11 ... fixing device, 12 ... cleaner, 13 ... opening cover, 14, 45 ... ground wiring, 15, 21, 34 ... power supply , 16 ... transfer belt, 19, 20, 44 ... side plate, 23 ... first support, 24, 46 ... first transfer power supply, 25 ... second support, 26, 43 ... transfer roller, 27, 47 ... Second transfer power source, 28, 29 ... transfer belt, 32 ... tension roller, 33 ... main body frame, 35 ... first roller shaft, 36 ... second roller shaft, 37 ... fixing means, 38 ... fixing screw, 40 ... guide.

Claims (6)

  In an image forming apparatus having a belt-like intermediate transfer member, the belt-like intermediate transfer member is held at a predetermined potential via at least two or more supports, and the support is formed on the surface with a conductive resin or conductive material. An image forming apparatus having an elastic body.   The image forming apparatus according to claim 1, wherein the support is a roller.   The image forming apparatus according to claim 1, wherein the support is grounded.   The image forming apparatus according to claim 3, wherein the support is connected to a portion that is a ground potential of a power source of the image forming apparatus.   5. The image forming apparatus according to claim 4, wherein the support is connected to the ground potential of the power source at at least two locations. 6. The image forming apparatus according to claim 1, wherein the intermediate transfer member constitutes a unit together with the support.

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