JP2006064962A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus suppressing cost increase and also suppressing the occurrence of failure due to poor point of contact. <P>SOLUTION: The image forming apparatus 1 is provided with a transfer means 24 with an image carrier rotating body 11 and a facing rotating body 5 installed in a pressurized contact with it and transferring a toner image on the image carrier rotating body 11 to transfer material 2, each of the image carrier rotating body 11 and the facing rotating body 5 are installed to a cover 65 which provides 11 and 5 to be freely opened and closed against an apparatus body 16 and the image carrier rotating body 11 and the facing rotating body 5 are brought into a pressurized contact with each other or freely separated from each other. A grounding point of contact 83 connected to grounding is provided on the apparatus body 16 and an electrical point of contact 82 is provided to the cover 65. The apparatus is constituted so that the grounding point of contact 83 is brought into contact with the electrical point of contact 82 when the cover 65 is closed and the electrical point of contact 82 is separated when the cover 65 is opened. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention transfers a toner image on an image carrying rotator to a transfer material by passing the transfer material through a transfer nip between an image carrying rotator carrying a toner image and a counter rotator facing the image carrying rotator. The present invention relates to an image forming apparatus such as a facsimile having a transfer means, a printer, an electrophotographic copying apparatus, and a plotter.

  Formed on the photoconductor by having a transfer roller consisting of an elastic roller that presses against the photoconductor to form a transfer nip, and applying a predetermined voltage to the transfer roller while passing the transfer material through the transfer nip An image forming apparatus having a transfer unit that transfers an electrostatic latent image onto a transfer material is generally known. In some image forming apparatuses, the transfer unit is configured to be detachable from the main body of the image forming apparatus in order to facilitate the jam processing operation after the transfer material is jammed. At the time of detachment, the transfer roller is separated from the photosensitive member to open the transfer nip, and the jammed transfer material can be easily removed.

  In the above-described type of image forming apparatus, the transfer unit can be detached from the main body of the image forming apparatus. Therefore, the voltage applied to the transfer roller is provided on the relay terminal provided on the main body of the image forming apparatus and on the side of the transfer means. It is supplied from the image forming apparatus main body through a power supply member. Here, if a voltage is constantly supplied from the image forming apparatus main body, a discharge phenomenon occurs when the relay terminal and the power supply member are separated when the transfer unit is detached, and between the relay terminal and the power supply member. An insulating material such as a wrinkle is generated, and the next time the transfer means is connected to the main body of the image forming apparatus, an energization failure occurs.

  Therefore, an open / close sensor is provided to detect when the transfer unit is detached from the image forming apparatus main body and stop energization of the relay terminal and the power supply member. For example, “Patent Document 1” discloses a technique in which energization is resumed before the relay terminal and the power feeding member are reliably connected before being separated.

JP 2001-312157 A

  As in the technique described in “Patent Document 1”, in an image forming apparatus in which a cover is provided so as to be openable and closable with respect to the main body of the image forming apparatus, and a transfer unit is provided on the cover, A configuration is adopted in which a ground contact is provided on the cover side, and the charge applied to the cover is further grounded to the image forming apparatus main body side via the contact.

  However, such a configuration requires a path for connecting the ground from the cover side to the main body of the image forming apparatus, and there is a problem that the ground path is complicated and the cost is increased. In addition, since there are two contacts, the contact between the transfer means and the ground on the cover side, and the contact on the cover side and the ground on the image forming apparatus main body side, there is a possibility that a problem due to a contact failure may occur. There is also a problem that it becomes high.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of solving the above-described problems and suppressing an increase in cost and occurrence of defects due to a contact failure.

  According to a first aspect of the present invention, there is provided an image carrying rotator for carrying a toner image, and an opposing rotator disposed in pressure contact with the image carrying rotator, the image carrying rotator, the opposing rotator, Transfer means for transferring a toner image on the image carrying rotator to the transfer material by passing the transfer material through a transfer nip formed in the pressure contact portion of the image bearing rotator, In the image forming apparatus in which the counter rotator is disposed in a cover provided to be openable and closable with respect to the apparatus main body, and the image carrying rotator and the counter rotator are provided so as to be able to press and separate from each other. The apparatus main body has a ground contact connected to ground, and the cover has an electrical contact. The ground contact contacts the electrical contact when the cover is closed and the electrical contact when the cover is opened. Characterized in that spaced apart from the. Examples of the image bearing rotator include a photosensitive drum and an intermediate transfer belt, and examples of the counter rotator include a roller and a belt.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the apparatus main body further includes bias applying means for applying a bias to the image bearing rotating body, and the electrical contact is a surface of the counter rotating body. It is electrically connected to.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the cover further includes a conductive member that contacts the transfer material that has passed through the transfer nip and discharges the transfer material. An electrical contact and the conductive member are electrically connected. Examples of the conductive member include a static elimination needle that removes charges from a transfer material after image transfer.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the ground contact is made of a conductive elastic member that press-contacts the electric contact. Examples of the conductive elastic member include a leaf spring made of conductive metal or resin.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect of the present invention, the image forming apparatus further includes a biasing unit that biases the counter rotating body toward the image bearing rotating body. The electrical contact is pressed while applying a biasing force from a direction orthogonal to the direction in which the biasing unit biases. Examples of the urging means include a compression spring and a leaf spring.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the conductive elastic member is in pressure contact with the electrical contact in the same direction as the rotation axis of the counter rotating body.

  According to the present invention, when the cover is closed with respect to the apparatus main body, the electrical contact and the ground contact are pressed against each other, so that the bias from the bias applying means is securely grounded to the apparatus main body side, and the cost is reduced with a simple configuration. It is possible to prevent the occurrence of contact failure without increasing the effect of the charge on the cover. Furthermore, since the direction in which the ground contact urges the electrical contact is substantially perpendicular to the direction in which the secondary transfer roller is urged against the intermediate transfer belt, the urging force exerted on the electrical contact by the ground contact is 2 It does not affect the urging force that urges the next transfer roller against the intermediate transfer belt, and it is possible to prevent deterioration in transfer performance due to a transfer nip position shift or the like over a long period of time.

  FIG. 1 is a schematic diagram of an image forming apparatus employing an embodiment of the present invention. In FIG. 1, a color printer 1 as an image forming apparatus has a transfer belt unit 10 having an intermediate transfer belt 11 as an image bearing rotating body and four image stations at the center of the apparatus main body 16. Each image station has photosensitive drums 20Y, 20C, 20M, and 20Bk, which are image carriers, around which are dedicated charging devices 30Y, 30C, 30M, and 30Bk, and cleaning devices 40Y, 40C, and 40M, respectively. , 40Bk, and developing devices 50Y, 50C, 50M, and 50Bk are disposed.

  A toner bottle group 9 containing replenishing toner is disposed at the top of the apparatus main body 16. Each toner bottle contains yellow (Y), cyan (C), magenta (M), and black (Bk) toners from the left in the figure, and each color toner corresponds through a supply path (not shown). The developing devices 50Y, 50C, 50M, and 50Bk are replenished.

  Here, an image forming operation of the image forming apparatus 1 will be described. When the transfer paper 2 as a transfer material is fed from the paper feed cassette 17 by the paper feed roller 3, and the leading edge of the transfer paper 2 reaches the registration roller pair 4, the leading edge is detected by a sensor (not shown). The registration roller pair 4 measures the timing based on a detection signal of a sensor (not shown), and conveys the transfer paper 2 to a transfer nip formed at a pressure contact portion between the secondary transfer roller 5 and the intermediate transfer belt 11.

  The photosensitive drums 20Y, 20C, 20M, and 20Bk are uniformly charged in advance by the corresponding charging devices 30Y, 30C, 30M, and 30Bk, and are exposed and scanned by the laser beam from the optical writing device 8 here. Thus, an electrostatic latent image is formed on the outer peripheral surface. Each electrostatic latent image is developed by the corresponding developing device 50Y, 50C, 50M, 50Bk for each color, and yellow, cyan, magenta, and black toner images are formed on the outer peripheral surfaces of the photosensitive drums 20Y, 20C, 20M, 20Bk. Are formed respectively.

  Next, primary transfer voltages are applied to the primary transfer rollers 12Y, 12C, 12M, and 12Bk, and the toner images on the photosensitive drums 20Y, 20C, 20M, and 20Bk are sequentially transferred onto the intermediate transfer belt 11. To go. The image forming operation for each color at this time is executed at different timings from the upstream side toward the downstream side so that the toner images are transferred to the same position on the intermediate transfer belt 11.

  The image formed on the intermediate transfer belt 11 moves to a position corresponding to the secondary transfer roller 5 which is a counter-rotating body, and is secondarily transferred to the transfer paper 2 at once. The transfer paper 2 on which the toner images of the respective colors are transferred is conveyed to a fixing device 6 where the toner image is fixed by heat and pressure, and discharged onto a paper discharge tray 15 that forms the upper surface of the apparatus main body 16 by a pair of paper discharge rollers 7. Is done.

  At the time of the above-described image formation, the residual toner remaining on the photosensitive drums 20Y, 20C, 20M, and 20Bk is cleaned by the corresponding cleaning devices 40Y, 40C, 40M, and 40Bk, respectively, and then the direct current has an AC component. Each of the charging devices 30Y, 30C, 30M, and 30Bk to which a bias is applied in a superimposed manner is charged at the same time as the charge removal, and prepares for the next image forming process. The residual toner remaining on the intermediate transfer belt 11 is cleaned by the intermediate transfer belt cleaning device 13 to prepare for the next image forming process.

  The intermediate transfer belt 11 is rotatably supported by the apparatus main body 16 and is driven to rotate by driving means (not shown), and a driven roller which is disposed opposite to the intermediate transfer belt cleaning device 13 and is rotatably supported by the apparatus main body 16. 22 by an entrance roller 23 that forms an entrance shape of the intermediate transfer belt 11 so as to guide the transfer paper 2 fed from the registration roller pair 4 to a transfer nip between the secondary transfer roller 5 and the intermediate transfer belt 11. Is supported. The transfer belt unit 10 and the secondary transfer roller 5 described above constitute a transfer device 24 as transfer means.

Next, the configuration of each image station will be described with reference to FIG. In addition, the code | symbol for every color is abbreviate | omitted here and it demonstrates as each color common.
The charging device 30 is a charging roller disposed in contact with or close to the photosensitive drum 20, and a cleaning roller 31 is disposed in contact with the charging device 30.

  The developing device 50 includes agitating and conveying members 53 and 54 for agitating and conveying the developer contained in the developing casing 55 to circulate, and the developer is supplied from the agitating and conveying member 53 to the developing roller 51 to develop Toner is supplied from the roller 51 to the photosensitive drum 20. Reference numeral 52 denotes a doctor blade that regulates the layer thickness of the developer on the developing roller 51.

  The cleaning device 40 includes a cleaning blade 41, a collecting member 42 that conveys and collects toner scraped off by the cleaning blade 41, a cleaning casing 43, and the like. In FIG. 2, reference symbol L indicates laser light emitted from the optical writing device 8, and reference symbol 14 indicates a frame of the transfer belt unit 10. The transfer belt unit 10 is moved by a moving mechanism (not shown) so that the intermediate transfer belt 11 contacts the photosensitive drum 20 at the time of image transfer, and is separated from the photosensitive drum 20 at the time of non-transfer of the image. Moved.

  As shown in FIG. 3, the secondary transfer roller 5 made of a conductive elastic body is rotatably supported by a support member 60 formed in a casing shape having a housing recess. In addition to the secondary transfer roller 5, the support member 60 guides the transfer sheet 2 from the intermediate transfer belt 11 and a guide member 61 that guides the transfer sheet 2 to the transfer nip between the intermediate transfer belt 11 and the secondary transfer roller 5. A neutralizing needle 62 as a conductive member for separation, a handle 63 that is gripped when attaching / detaching and transporting the support member 60, and the like are provided. The static elimination needle 62 is disposed so that the needle-shaped portion contacts the transfer paper 2 after passing through the transfer nip.

  The support member 60 is detachably attached to a cover 65 attached to the apparatus main body 16 so as to be openable and closable in the direction indicated by reference numeral 64 in FIG. The belt 11 and the secondary transfer roller 5 are separated from each other to open the transfer nip.

  The support member 60 is rotatably supported at its lower end by a cover 65, and as shown in FIG. 4, the intermediate transfer belt 11 side is provided by a compression coil spring 66 as an urging means restricted at one end by the cover 65. It is energized towards. The compression coil springs 66 are disposed at two locations that are both ends in the axial direction of the secondary transfer roller 5. Due to the urging force of the compression coil spring 66, the secondary transfer roller 5 is pressed against the intermediate transfer belt 11 in the direction indicated by reference numeral 67 in FIG. 4 and transferred between the secondary transfer roller 5 and the intermediate transfer belt 11. A nip is formed.

  In FIG. 4, reference numeral 68 indicates bias applying means for applying a bias to the intermediate transfer belt 11. The bias applying means 68 constitutes a part of the transfer device 24 and applies a bias to the shaft portion of the driving roller 21 that is a bias applying roller. The shaft portion of the driving roller 21 is made of a conductive material such as stainless steel, and the bias applied to the driving roller 21 is configured to be able to conduct to the intermediate transfer belt 11, the transfer paper 2, and the secondary transfer roller 5. ing.

  As shown in FIG. 5, the apparatus main body 16 is provided with a holder 81 that can rotatably support the shaft portion 5 a of the secondary transfer roller 5. The holder 81 is made of a conductive member, and the holder 81 and the static elimination needle 62 are electrically connected. The shaft portion 5a is also made of a conductive member such as a stainless material, so that when the cover 65 is closed, the shaft portion 5a is supported by the holder 81 and applied from the bias applying means 68 to the drive roller 21. A bias is also applied to the static elimination needle 62 via the secondary transfer roller 5. In addition, illustration of the cover 65 is abbreviate | omitted in FIG.

  On the other end of the holder 81 opposite to the end on which the shaft portion 5a is inserted, a ground plate 83 as a ground contact is attached to the frame of the apparatus body 16 and connected to a ground (not shown). Is arranged. The ground plate 83 made of a conductive elastic member is arranged so that its free end enters the holder 81, and the shape of the free end is on the other end side when the shaft portion 5 a is fitted into the holder 81. It is elastically deformed and is formed in a shape that comes into pressure contact with the end face 82 of the shaft portion 5a. The end face 82 is chamfered to facilitate the contact of the ground plate 83. At the time of contact with the ground plate 83, the end face 82 functions as an electrical contact, and the ground plate 83 biases the shaft portion 5a in the axial direction (the arrow direction indicated by reference numeral 84 in FIG. 5).

  With the above configuration, when the cover 65 is opened with respect to the apparatus main body 16, the shaft portion 5a is detached from the holder 81 as shown in FIG. Is not granted. In the state where the cover 65 is closed with respect to the apparatus main body 16, the shaft portion 5 a is supported by the holder 81 as shown in FIG. 5, and the end face 82 and the ground plate 83 are pressed against each other. The bias is reliably grounded to the apparatus main body 16 side, and the influence of electric charges on the cover 65 can be reduced by preventing the occurrence of contact failure without increasing the cost with a simple configuration.

  In the present embodiment, the direction in which the ground plate 83 biases the end face 82 is substantially perpendicular to the direction in which the compression coil spring 66 biases the secondary transfer roller 5, so that the ground plate 83 is supported by the support shaft 5 a. The urging force exerted on the transfer coil spring 66 does not affect the urging force applied to the secondary transfer roller 5 by the compression coil spring 66, and it is possible to prevent deterioration in transfer performance due to transfer nip position deviation or the like over a long period of time. Become.

1 is a schematic front view of an image forming apparatus employing an embodiment of the present invention. It is the schematic of the image station used for one Embodiment of this invention. It is a perspective view of the principal part of the transfer apparatus used for one Embodiment of this invention. It is a schematic front view of the principal part of the transfer apparatus used for one Embodiment of this invention. It is a perspective view of the principal part of the transfer device when the cover is closed in one embodiment of the present invention. FIG. 4 is a perspective view of a main part of the transfer device when the cover is opened in the embodiment of the present invention.

Explanation of symbols

1 Image forming device (color printer)
2 Transfer material (transfer paper)
5 Counter rotating body (secondary transfer roller)
11 Image bearing rotator (intermediate transfer belt)
16 Device body 24 Transfer means (transfer device)
62 Conductive member (static charge needle)
65 Cover 66 Biasing means (compression coil spring)
68 Bias applying means 82 Electrical contact (end face)
83 Ground contact (ground plate)

Claims (6)

A transfer formed on a pressure contact portion between the image carrying rotator and the counter rotator, the image carrying rotator carrying a toner image, and an opposing rotator arranged in pressure contact with the image carrying rotator. Transfer means for transferring a toner image on the image carrying rotator to the transfer material by passing a transfer material through a nip, the image carrying rotator in the apparatus main body, and the counter rotator in the apparatus main body. In the image forming apparatus in which the image bearing rotating body and the counter rotating body are respectively disposed in a cover that is freely openable and closable, and can be pressed and separated from each other.
The apparatus main body has a ground contact connected to ground, and the cover has an electrical contact, and the ground contact contacts the electrical contact when the cover is closed and the electrical contact when the cover is opened. An image forming apparatus characterized by being separated. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the apparatus main body includes bias applying means for applying a bias to the image bearing rotating body, and the electrical contact is electrically connected to a surface of the counter rotating body. The image forming apparatus according to claim 1 or 2,
The cover includes a conductive member that contacts the transfer material that has passed through the transfer nip to neutralize the transfer material, and the electrical contact and the conductive member are electrically connected. Image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus according to claim 1, wherein the ground contact is made of a conductive elastic member that is pressed against the electrical contact. The image forming apparatus according to claim 4.
There is urging means for urging the counter rotator toward the image bearing rotator, and the conductive elastic member applies an urging force to the electrical contact from a direction perpendicular to the direction in which the urging means urges. An image forming apparatus that is pressed while being applied. The image forming apparatus according to claim 5.
The image forming apparatus, wherein the conductive elastic member is in pressure contact with the electrical contact in the same direction as a rotation axis direction of the counter rotating body.

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