JP2016142818A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device for preventing electric charges from accumulating in a steel reinforcement member for a notched part of a frame in the support structure of a roller to which a bias voltage is applied.SOLUTION: A power feeding member (201) sends a bias voltage from a power supply to an electricity-conductive spring (202). A bearing (203) receives a bias voltage together with an elastic force from the spring. A roller (24) is rotatably held by the bearing and makes contact with a material to be transferred, and, while receiving the bias voltage from the spring through the bearing, is urged by the spring toward the material to be transferred. An insulating frame (205) includes a notched part (205C) having a clearance (GAP) opened inside, and supports the bearing inserted in the clearance. The roller is removable through the clearance. A steel reinforcement member (206) is disposed so as to stride the clearance, reinforcing a strength of the notched part. A contact part (210) of the power feeding member comes in contact with the reinforcement member, and maintains it at the same potential as the spring.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus, and more particularly to a structure for supporting a roller built in the apparatus.

  In an image forming apparatus, a roller is used for various purposes. For example, in an electrophotographic apparatus, the conveyance roller moves the sheet by a frictional force generated between the outer peripheral surface and the sheet by rotation. The photosensitive drum is repeatedly subjected to a series of image forming processes such as charging, exposure, development, transfer, and cleaning by rotating the photosensitive drum. The developing roller carries toner on its outer peripheral surface to the electrostatic latent image on the photoreceptor by rotation. The transfer roller rotates and contacts the transfer material such as an intermediate transfer member and a sheet on the outer peripheral surface thereof, and forwards it, and the transfer material is transferred to the photosensitive drum and the intermediate transfer member with the transfer material separated. An electric field is generated between the materials. This electric field causes the toner image to be transferred from the transfer material to the transfer material. While the fixing roller rotates, it contacts the transfer material on its outer peripheral surface and sends it forward, and heats / pressurizes the transfer material. The heat and pressure at this time fix the toner image on the transfer material.

  Various functions are mounted on the support structure depending on the type of roller. For example, the transfer roller is supported by the frame via its bearings. The bearing and the frame are connected by a spring. The transfer roller is biased toward the transfer material by the spring. This spring also forms part of a feed path that transmits a voltage that differs from the ground voltage by a predetermined difference, ie, a bias voltage, from the power source to the bearing. This bias voltage is applied from the spring to the transfer roller through the bearing. On the other hand, since the frame is made of an insulator, current leakage from the transfer roller due to application of a bias voltage is prevented. As a result, the potential on the outer peripheral surface of the transfer roller is maintained at the bias voltage, and an electric field is generated between the outer peripheral surface and the transfer material. Further, as disclosed in Patent Document 1, for example, the frame is provided with a notch, and a bearing is inserted into a gap opened in the notch. In this case, since the transfer roller can be removed through the gap, the replacement is easy.

JP 2005-315991 A

When the roller bearing is supported by the cutout portion of the frame, it is desirable to reinforce the cutout portion with a member other than the frame. This is due to the following reason.
Stress is likely to concentrate on the notch due to its structure. In particular, roller bearings that contact other objects on the outer peripheral surface thereof, such as transport rollers and transfer rollers, are fixed to the support structure by being biased by a spring or the like. Concentrate on the notch. The notch needs to be strong enough to withstand this stress concentration.

  However, the material of the frame is generally low in strength. This is because the material is required to be easily molded in order to cope with the complexity of the shape of the frame accompanying the multifunctional support structure. Furthermore, in a support structure for a roller, such as a transfer roller, to which a bias voltage is applied from a power source, the frame material needs to have an insulation property that prevents current leakage from the roller. Materials that are easy to mold and have insulating properties are generally lower in strength than metals, including resins. Therefore, it is difficult to increase the strength of the notch by selecting the material of the frame while keeping the frame easy to mold and insulating. In addition, increasing the thickness / thickness for the purpose of increasing the strength of the notch is not preferable because it may hinder downsizing of the support structure and further hinder downsizing of the entire image forming apparatus.

  On the other hand, when the cutout portion of the frame is reinforced with a member different from the frame, this member does not require as much formability and insulation as the frame. Actually, since this member only needs to be attached to the frame, its shape may be a simple one such as a bar or a plate. Even if this member is conductive, it is possible to prevent current from leaking from the roller through the member as long as the installation location is sufficiently away from the roller.

This member is preferably made of metal. If it is made of metal, a reinforcing member having a required strength can be easily manufactured. However, the metal reinforcing member has the following problems.
In a support structure for a roller to which a bias voltage is applied, such as a transfer roller, an urging member such as a spring transmits the bias voltage to a roller bearing. Since this spring is close to the cutout portion of the frame that supports the bearing, it is also close to the reinforcing member. Therefore, if the reinforcing member is made of metal, electric charge is accumulated in the reinforcing member every time the spring transmits a bias voltage to the bearing. Since the bias voltage is generally a high value of about 1 kV, if charge accumulation in the reinforcing member lasts for a long period of time, a user or maintenance personnel mistakenly touch this reinforcing member when replacing the transfer roller, etc. Even the risk of doing so could arise. Therefore, a device for preventing this electric shock is necessary for the metal reinforcing member.

  The object of the present invention is to solve the above-mentioned problems, and in particular, even in a support structure for a roller to which a bias voltage is applied, even if the reinforcing member for the notch portion of the frame is made of metal, charge accumulation there An object of the present invention is to provide an image forming apparatus capable of preventing the above-described problem.

  An image forming apparatus according to one aspect of the present invention is an image forming apparatus that forms an electrostatic latent image on a charged photoconductor by exposure, develops the electrostatic latent image, and transfers the image from the photoconductor to a transfer material. And a roller facing the photosensitive member or the transfer material, a bearing for rotatably holding the roller, and an insulating frame for housing the bearing. The frame includes an opening at a portion facing the photosensitive member or the transfer material, and a notch portion having a gap along the end surface in the axial direction of the roller from the opening, and a gap between the notch portions. A conductive spring with a proximal end connected to the back and a distal end extending toward the opening, a power supply member that supplies power to the proximal end of the spring, and the notch so as to straddle the gap between the notches And a metal reinforcing member attached to the end face of the. The bearing is fixed in the notch so that the roller is removable through the opening of the notch and contacts the tip of the spring, and is biased toward the photoreceptor or the transfer material by the spring. At the same time, power is supplied to the roller from the tip of this spring. A path for supplying power from the power supply member to the bearing through the spring is also electrically connected to the reinforcing member.

  The spring is a coil spring sandwiched between the power supply member and the bearing, and the power supply member has a plate shape, and a plate surface facing the bearing across the spring, and extends from the plate surface toward the bearing. And a contact portion that contacts the reinforcing member. Further, the reinforcing member is plate-shaped, and the plate surface extends along the end surface of the cutout portion toward the side opposite to the opening of the cutout portion, and the contact portion of the power supply member is a roller of the reinforcement member. You may contact the edge located on the opposite side.

  The roller may be used for any of transfer from a photoreceptor to a transfer material, development of an electrostatic latent image, charging of the photoreceptor, or cleaning of the photoreceptor. The frame may support the bearing at both ends of the roller, the reinforcing member may be disposed at both ends of the roller, and the power supply member and the conductive spring may be disposed only at the same end of the roller.

  In the roller support structure provided in the image forming apparatus according to the above aspect of the present invention, a path for supplying power to the roller through a spring that urges the roller toward the photosensitive member or the like is made of metal with respect to the cutout portion of the frame. The reinforcing member is also electrically connected. Thereby, this reinforcement member is maintained at the same potential as the spring and the roller. In this way, this image forming apparatus can prevent accumulation of electric charges on the metal reinforcing member.

1 is a schematic front view illustrating a structure of an image forming apparatus according to an embodiment of the present invention. (A), (b), (c) is the front view, axial sectional view, and side view of a transfer roller and its supporting structure, respectively. FIG. 3 is an exploded view of essential parts of the transfer roller and its support structure shown in FIG. 2. (A) is the enlarged view of the principal part of the side surface of the transfer roller shown in (c) of FIG. 2 and its support structure, and (b) when the reinforcing plate is removed from the principal part shown in (a) FIG. FIG. 3 is an exploded view of a power feeding plate and a spring shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Structure of image forming apparatus]
FIG. 1 is a schematic front view showing the structure of an image forming apparatus according to an embodiment of the present invention. In FIG. 1, elements inside the image forming apparatus 100 are depicted as if they were seen through the front surface of the housing.

Referring to FIG. 1, an image forming apparatus 100 is, for example, a multi-function peripheral (MFP) and includes an image forming unit. The image forming unit is an element that forms a toner image on a sheet based on image data, and includes a feeding unit 10, an image forming unit 20, a fixing unit 30, and a paper discharge unit 40.
-Feeding section-
The feeding unit 10 rotates the transport roller groups 12, 13, and 14 installed along the sheet transport path from the paper feed cassette 11 to the image forming unit 20, thereby feeding the sheet SHT from the paper feed cassette 11 to 1. Each sheet is fed to the image forming unit 20. “Sheet” refers to a thin film-like or plate-like material or article such as paper or film resin. The sheet type of the sheet SHT that can be stored in the sheet feeding cassette 11 is plain paper, high-quality paper, color paper, or coated paper, and the size is A3, A4, A5, or B4. The timing roller 14 closest to the image forming unit 20 in the transport roller group is generally stopped even during the execution of the print job, and rotates according to the drive signal from the main control unit, and at the timing indicated by the drive signal. SH2 is sent to the image forming unit 20.

-Image forming part-
The image forming unit 20 forms a toner image on the sheet SH2 sent from the feeding unit 10.
Specifically, each of the four image forming units 21 </ b> Y, 21 </ b> M, 21 </ b> C, and 21 </ b> K first causes each part of the outer peripheral surface to face the charger 26 while rotating the photosensitive drum 25. As a result, the opposed portions are uniformly charged.

  Next, each of the image forming units 21Y,... Irradiates the charged portion of the photosensitive drum 25 with the laser light from the exposure unit 27, and scans the outer peripheral surface of the photosensitive drum 25 with the light. At this time, the exposure unit 27 further modulates the amount of laser light based on the gradation values of each color of yellow (Y), magenta (M), cyan (C), and black (K) represented by the image data. As a result, an electrostatic latent image representing an image of each color is generated on the outer peripheral surface of the photosensitive drum 25.

The image forming units 21Y,... Subsequently rotate the developing roller 28 so that the outer peripheral surface of the image forming unit 21Y is covered with toner of each color of Y, M, C, K and is opposed to the outer peripheral surface of the photosensitive drum 25. Thereby, the electrostatic latent image thereon is developed with the toner of each color. In this way, four-color images represented by the image data are reproduced as toner images of one color on each outer peripheral surface of the four photosensitive drums 25.
The drive rollers 23L and 23R rotate the intermediate transfer belt 23 to pass through the nip between the four pairs of primary transfer rollers 22 and the photosensitive drum 25 in order, and each portion of the surface of the intermediate transfer belt 23 passes through each photosensitive member. Contact the drum 25. At this time, since the primary transfer roller 22 is maintained at a potential different from that of the photosensitive drum 25 by application of a bias voltage, an electric field is generated between the primary transfer roller 22 and the photosensitive drum 25. This electric field sequentially transfers the toner images of the respective colors from the outer peripheral surface of each photosensitive drum 25 to the same position on the surface of the intermediate transfer belt 23. As a result, one color toner image is formed at that position.

  The secondary transfer roller 24 rotates with the rotation of the driving roller 23R, and the surface of the intermediate transfer belt 23 is brought into contact with the sheet SH2 that has been fed from the feeding unit 10 to the nip between both the rollers 23R and 24. At this time, since the secondary transfer roller 24 is maintained at a potential different from that of the intermediate transfer belt 23 by applying a bias voltage, an electric field is generated between the surface of the intermediate transfer belt 23 and the secondary transfer roller 24. Yes. This electric field transfers the color toner image from the intermediate transfer belt 23 to the surface of the sheet SH2. Thereafter, the driving roller 23R and the secondary transfer roller 24 send the sheet SH2 to the fixing unit 30 by rotation.

  After the transfer of the toner image from the photosensitive drum 25 to the intermediate transfer belt 23, each image forming unit 21Y,... Cleans the photosensitive drum 25 with a cleaner 29, and the toner remaining after the transfer from the outer peripheral surface thereof. Remove. The cleaner 29 is a blade or a brush installed between the primary transfer roller 22 and the charger 26, and comes into contact with a portion of the outer peripheral surface of the photosensitive drum 25 immediately after contacting the intermediate transfer belt 23. Scrape toner off.

-Fixing part-
The fixing unit 30 heat-fixes the toner image on the sheet SH2 sent out from the image forming unit 20. Specifically, the fixing unit 30 passes the sheet SH2 through the nip between the fixing roller 31 and the pressure roller 32 while rotating the fixing roller 31 and the pressure roller 32. At this time, the fixing roller 31 applies heat of a built-in heater to the surface of the sheet SH2, and the pressure roller 32 applies pressure to the heated portion of the sheet SH2 and presses it against the fixing roller 31. The toner image is fixed on the surface of the sheet SH <b> 2 by the heat from the fixing roller 31 and the pressure from the pressure roller 32. The fixing unit 30 further sends the sheet SH <b> 2 to the paper discharge unit 40 by the rotation of the fixing roller 31 and the pressure roller 32.

-Output section-
The paper discharge unit 40 discharges the sheet SH3 on which the toner image is fixed to the paper discharge tray 46. Specifically, first, the sheet SH <b> 3 moves from the upper part of the fixing unit 30 along the guide plate 41 to the paper discharge port 42. At this time, the paper discharge unit 40 rotates the paper discharge roller 43 disposed inside the paper discharge port 42 and feeds the sheet SH3 out of the paper discharge port 42 on its outer peripheral surface. Thus, the sheet SH3 is accommodated in the paper discharge tray 46.

[Support structure of transfer roller]
2, 3 and 4 show the secondary transfer roller 24 and its support structure according to an embodiment of the present invention. Specifically, (a), (b), and (c) of FIG. 2 are a front view, a cross-sectional view along a line bb shown in (a), and a side view, respectively, and FIG. FIG. 4A is an enlarged side view of the main part, and FIG. 4B is an enlarged side view when the reinforcing plate 206 is removed from the main part. 2 to 4, the support structure includes a power terminal 200, a power feeding plate 201, a spring 202, a bearing 203, a frame 205, and a reinforcing plate 206.

-Frame-
The frame 205 is a substantially plate-like member formed from an insulating resin. Referring to FIGS. 2A and 2B, the frame 205 is fixed in the casing of the MFP 100 so that the front surface 205F extends in the vertical direction. Although not shown in FIG. 2, the front surface 205F is disposed so as to face the driving roller 23R located in front of the front surface 205F.

−Power supply terminal−
The power supply terminal 200 passes through the frame 205 perpendicularly to the plate surface. An end portion 200A of the power terminal 200 located on the back side of the frame 205 (upper side of the drawing in FIG. 2B) is a power source installed inside the back plate of the MFP 100 (none of the drawings is shown). And receives a bias voltage therefrom. This power source rectifies AC power from an external commercial AC power source, for example, and converts it into a bias voltage which is a DC voltage of about 1 kV, for example. On the other hand, the end portion 200B of the power terminal 200 located on the front surface 205F side of the frame 205 (the lower side of the drawing in FIG. 2B) is connected to the power supply plate 201.

-Power supply plate-
The power feeding plate 201 is a metal plate-like member containing aluminum, copper, an alloy containing them, carbon steel, a steel alloy, or the like. Referring to FIGS. 2B, 3, and 4, the power supply plate 201 is disposed on the front surface 205 </ b> F of the frame 205, and the plate surface faces the bearing 203 with the spring 202 interposed therebetween. As shown in FIG. 2B and FIG. 3, the power supply plate 201 has two through holes 201A and 201B, one of which 201A is inserted with a protrusion 205P on the front surface 205F of the frame 205, and the other 201B has The end 200B of the power terminal 200 is inserted. The power supply plate 201 is connected to the end 200B of the power supply terminal 200, and receives a bias voltage from the power supply through the power supply plate 201.

-Spring-
The spring 202 is a coil spring made of metal such as carbon steel or steel alloy. Referring to FIG. 2B, FIG. 3 and FIG. 4B, the spring 202 is sandwiched between the plate surface of the power supply plate 201 and the bearing 203, and the base end of the spring 202 is The projection 205P of the front surface 205F of the frame 205 exposed through the through hole 201A is fitted. As a result, the spring 202 biases the bearing 203 forward. The spring 202 is further conductive, contacts the power supply plate 201 at the base end portion thereof, receives a bias voltage from the power supply plate 201, and transmits the bias voltage to the bearing 203. That is, the spring 202, together with the power supply terminal 200 and the power supply plate 201, forms a power supply path for transmitting a bias voltage from the power supply to the bearing 203.

-Bearing-
The bearing 203 is a member formed from, for example, resin, and holds the secondary transfer roller 24 so as to be rotatable around its axis. 2 to 4, a semi-cylindrical recess 203H is provided on the front surface of the bearing 203, and the shaft 24S of the secondary transfer roller 24 is slidably fitted in the recess 203H. The bearing 203 is further conductive. Specifically, the resin itself constituting the bearing 203 has conductivity, or the surface of the resin is covered with a conductor such as metal. Due to this conductivity, the bearing 203 transmits a bias voltage from the spring 202 to the secondary transfer roller 24. The bearing 203 receives an elastic force from the spring 202 and transmits it to the secondary transfer roller 24.

-Frame cutout-
Referring to FIGS. 2B and 2C, both end faces of the frame 205 in the axial direction of the secondary transfer roller 24, that is, the two side faces 205S both protrude to the front of the front face 205F. . Referring to (c) of FIG. 2, FIG. 3, and (b) of FIG. 4, each tip of these side surfaces 205S includes a notch 205C. The notch 205C includes an opening 205O at the tip of the side surface 205S of the frame 205, and a gap GAP is opened from the opening 205O along the side surface 205S of the frame 205. That is, the notch 205C has a “U” or “U” shape.

  3 and 4B, a pair of bearings 203 and springs 202 are inserted into the gap GAP. The bearing 203 is in contact with the inner surface of the notch 205C at the upper surface and the lower surface. More specifically, three protrusions 203A, 203B, and 203C are arranged in a zigzag shape on the upper surface and the lower surface of the bearing 203, respectively, and the wall portion 205W of the notch portion 205C facing the gap GAP is sandwiched therebetween. . As a result, the entire bearing 203 can slide in the depth direction of the gap GAP (the direction of the arrow ARW shown in FIGS. 3 and 4B and the opposite direction). The spring 202 extends in the gap GAP from the projection 205P of the front surface 205F of the frame toward the opening 205O, and contacts the back surface of the bearing 203 at the tip. When the bearing 203 slides, the spring 202 expands and contracts accordingly and functions as a buffer member. That is, the spring 202 absorbs the vibration / impact that the bearing 203 receives through the secondary transfer roller 24 from the intermediate transfer belt 23, the sheet to be transferred, and the like due to its elasticity.

-Secondary transfer roller-
Referring to FIGS. 2A and 2B, the secondary transfer roller 24 includes a shaft 24S, a main body 24B, and a gear 24G. The shaft 24S is a metal rod-shaped member such as aluminum or an alloy thereof, carbon steel, or a steel alloy. The main body 24B is a cylindrical member made of an elastic member having conductivity, such as conductive rubber, and penetrates the shaft 24S along its central axis. Although not shown in FIG. 2 to FIG. 4, the main body 24 </ b> B faces the driving roller 23 </ b> R located in front of the frame 205 and sandwiches the intermediate transfer belt 23 in the nip between the driving roller 23 </ b> R by the elastic force of the spring 202. . The gear 24G is connected to one end of the shaft 24S and transmits the driving force from the motor to the shaft 24S. This driving force compensates the rotational force that the secondary transfer roller 24 receives from the frictional force between the main body 24B and the driving roller 23R, and prevents a delay in rotation due to the slip therebetween.

  As shown in FIG. 1, the sheet SH <b> 2 is passed from the feeding unit 10 to the nip between the secondary transfer roller 24 and the intermediate transfer belt 23. 2-4, the sheet moves from bottom to top. The outer peripheral surface of the main body 24B of the secondary transfer roller 24 comes into contact with this sheet, and the sheet is fed to the guide surface 205G provided on the upper part of the frame 205 and further to the fixing unit 30 (see FIG. 1) on the upper part. At this time, the elastic force of the spring 202 presses the sheet against the surface of the intermediate transfer belt 23 through the main body 24 </ b> B, and the electric field between the intermediate transfer belt 23 and the secondary transfer roller 24 causes the toner image on the intermediate transfer belt 23. Act on. As a result, the toner image is transferred from the intermediate transfer belt 23 to the sheet.

−Reinforcement plate−
The reinforcing plate 206 is a metal plate-like member such as carbon steel or steel alloy. 2 to 4, the reinforcing plates 206 are attached to the side surface 205S of the frame 205 one by one. As shown in FIGS. 2C, 3 and 4A, the reinforcing plate 206 is fitted into the recess 205V of the side surface 205S of the frame 205, and is opposite to the secondary transfer roller 24 along the side surface 205S. It spreads toward the side and straddles the gap GAP of the notch 205C.

The reinforcing plate 206 includes an overhang portion 206T at the edge of the cutout portion 205C on the side close to the opening portion 205O. The overhanging portion 206T extends forward from the edge (in the direction of the arrow ARW shown in FIGS. 3 and 4B) and is a hole formed in the surface of the opening 205O facing the recess 205V of the frame 205 (FIG. 3). 4 is not shown).
The reinforcing plate 206 has three through holes 206A, 206B, and 206C. A male screw 207 is inserted into the central through hole 206A and is screwed into a screw hole 205H formed in the recess 205V of the frame 205. The dowels D1 and D2 protruding from the recesses 205V of the frame 205 are inserted one by one into the through holes 206B and 206C on both sides.

  In this way, the reinforcing plate 206 is stably fixed to the side surface of the cutout portion 205C in a posture across the gap GAP. At this time, as shown in FIG. 2B, the reinforcing plate 206 is fixed at a distance from the surface of the bearing 203 exposed in the gap GAP, and as shown in FIG. 2C and FIG. The edge of the secondary transfer roller 24 has a shape with a sufficient distance from the shaft 24S. That is, the reinforcing plate 206 is not in direct contact with either the bearing 203 or the shaft 24S of the secondary transfer roller 24. Therefore, when the frame 205 is an insulator, current does not leak from the secondary transfer roller 24 to the reinforcing plate 206. Furthermore, since the reinforcing plate 206 straddles the gap GAP of the notch 205C, the strength of the notch 205C is supplemented. As a result, the stress concentration at the notch 205C due to the elastic force of the spring 202 is alleviated, so that the strength of the frame 205 is improved.

  Referring to FIGS. 2A and 2B, one bearing 203 is inserted into the notch 205C of each side surface 205S of the frame 205, and the shaft 24S of the secondary transfer roller 24 is interposed between them. It is growing. Thus, both ends of the secondary transfer roller 24 are supported by the frame 205. At this time, as shown in FIGS. 2A, 2C, and 4, the gap GAP of the notch 205C is opened forward (in the direction of the arrow ARW shown in FIGS. 3 and 4B). Therefore, the secondary transfer roller 24 can be easily removed.

  Similar to these bearings 203, both the spring 202 and the reinforcing plate 206 are disposed at both ends of the secondary transfer roller 24. On the other hand, the power terminal 200 and the power supply plate 201 are disposed only on the same end of the secondary transfer roller 24. That is, only one of the two springs 202 connected to the power supply plate 201 is used as a power supply path for transmitting a bias voltage from the power source to the bearing 203. Therefore, unlike the other of the pair of bearings 203, the one located on the side opposite to the power supply plate 201 with respect to the secondary transfer roller 24 may not have conductivity.

[Details of power supply plate shape]
FIG. 5 is an exploded view of the power feeding plate 201 and the spring 202. 4 and 5, the power supply plate 201 includes a contact portion 210. The contact portion 210 is a portion where the edge of the plate surface of the power supply plate 201 is bent and extended toward the bearing 203, and as shown in FIG. 4, the tip thereof is connected to the secondary transfer roller 24 of the reinforcing plate 206. Touches the opposite edge. The bias voltage is also applied to the reinforcing plate 206 through the contact portion 210 while propagating from the power feeding plate 201 to the spring 202. As a result, the reinforcing plate 206 is maintained at the same potential, that is, substantially equal to the bias voltage, for all of the power feeding path including the power feeding plate 201, the spring 202, and the bearing 203, and the secondary transfer roller 24. Therefore, while the bias voltage is applied to the secondary transfer roller 24, charge accumulation does not occur on the reinforcing plate 206. Further, after the power supply to the secondary transfer roller 24 is cut off, the potential of the reinforcing plate 206 drops from the bias voltage to the ground voltage together with the potentials of the secondary transfer roller 24 and the power supply paths 201, 202, and 203. Thus, there is no risk of electric shock if a user or maintenance personnel accidentally touches the reinforcing plate 206.

[Advantages of the embodiment]
In MFP 100 according to the embodiment of the present invention, as described above, power supply plate 201 including the support structure of secondary transfer roller 24 includes contact portion 210 and contacts reinforcing plate 206 therethrough. Thus, the bias voltage is always applied to the reinforcing plate 206 through the contact portion 210 when propagating from the power feeding plate 201 to the spring 202. As a result, the reinforcing plate 206 is maintained at substantially the same potential for all of the power supply plate 201, the spring 202, the bearing 203, and the secondary transfer roller 24, so that charge accumulation does not occur in the reinforcing plate 206. . Thus, even if the reinforcing plate 206 is made of metal, the MFP 100 can reliably prevent charge accumulation on the reinforcing plate 206 due to application of a bias voltage to the secondary transfer roller 24. This improves the safety against electric shock when the secondary transfer roller 24 is replaced.

[Modification]
(A) The image forming apparatus 100 shown in FIG. 1 is an MFP. In addition, the image forming apparatus according to the embodiment of the present invention may be any of a laser printer, an ink jet printer, a facsimile, a copier, and the like.
(B) The roller support structure shown in FIGS. 2 to 4 is intended for the secondary transfer roller 24. In addition, the support structure according to the embodiment of the present invention may target the primary transfer roller 22. That is, the transfer material may be the photosensitive drum 25 instead of the intermediate transfer belt 23, and the transfer material may be the intermediate transfer belt 23 instead of the sheet. The embodiment of the present invention can also be applied to a support structure for a transfer roller when the transfer material is a photosensitive drum and the transfer material is a sheet.

  Support structures according to embodiments of the present invention can be further targeted with only a roller that receives a bias voltage. Examples of such a roller include a charger, a developing roller, and a rotating brush of a cleaner. That is, the present invention can be applied to a support structure of a roller used for charging a photosensitive member, developing an electrostatic latent image, or cleaning the photosensitive member in an image forming process.

(C) The bearing 203 shown in FIGS. 2 to 4 is entirely conductive. In addition, the bearing itself may incorporate a conductive path instead of the main body itself being an insulator. The conductive path is composed of a conductive wire, a metal strip, and the like, and transmits a bias voltage from the spring 202 to the secondary transfer roller 24.
(D) The shapes of the power supply plate 201, the spring 202, the bearing 203, the cutout portion 205 </ b> C of the frame 205, and the reinforcing plate 206 shown in FIGS. 2 to 4 are merely examples. For example, the power supply member for the spring 202 may be in the form of a line or a strip instead of a plate. The spring is not limited to the coil spring 202 but may be another form such as a leaf spring. The bearing may be integrated with the roller. The cutout portion of the frame may be a curved shape such as an arc instead of a linear contour. The reinforcing member may be in the form of a bar, a net, a lattice, a ridge, or the like instead of the plate shape.

  (E) In the above embodiment, the contact portion 210 of the power supply plate 201 contacts the reinforcing plate 206. In addition, any part of the power supply path from the power supply plate to the bearing, such as the base end portion of the spring 202, may be electrically connected to the reinforcing plate. However, the deviation of the potential of the secondary transfer roller 24 from the bias voltage due to the inductance or capacitance parasitic between the power supply path and the reinforcing plate must be suppressed to be negligible.

  (F) Embodiments of the present invention are not limited to the roller support structure included in the image forming apparatus. In other words, the present invention is applicable as long as the spring included in the roller support structure is also used as a bias voltage feeding path for the roller.

  The present invention relates to a roller support structure in an image forming apparatus. As described above, a power supply member that applies a bias voltage to a spring is also brought into contact with a metal reinforcing member. Thus, the present invention is clearly industrially applicable.

100 MFP
24 Secondary transfer roller 24B Secondary transfer roller main body 24G Gear 24S Secondary transfer roller shaft 201 Power feeding plate 210 Contact portion of power feeding plate 202 Spring 203 Bearing 203A-C Projection on upper and lower surfaces of bearing 203H Semi-cylindrical shape of bearing Dent 205 frame 205C frame notch 205F frame front 205H frame side screw hole 205O frame notch 205P frame front projection 205S frame side 205V frame side recess 205W frame notch wall Portions D1, D2 Dowels on the side of the frame GAP Frame gap notch portion depth direction ARW Frame notch depth direction 206 Reinforcement plate 206A-C Three through holes in the reinforcement plate 206T Reinforcement plate overhanging portion 207 Male screw

Claims (8)

An image forming apparatus that forms an electrostatic latent image on a charged photoconductor by exposure, develops the electrostatic latent image, and transfers the image from the photoconductor to a transfer material;
A roller facing the photoconductor or the transfer material;
A bearing for rotatably holding the roller;
An insulating frame that houses the bearing;
With
The frame is
A notch that includes an opening at a portion facing the photoconductor or the transfer material, and a gap is open from the opening along an end surface in the axial direction of the roller;
A conductive spring having a proximal end connected to the back of the gap of the notch and a distal end extending toward the opening of the notch;
A power supply member for supplying power to the proximal end of the spring;
A metal reinforcing member attached to the end face of the notch so as to straddle the gap of the notch,
Including
The bearing is fixed in the notch so that the roller is removable through the opening of the notch and contacts the tip of the spring, and the photoreceptor or the material to be transferred by the spring. And is fed to the roller from the tip of the spring,
An image forming apparatus, wherein a path for supplying power from the power supply member to the bearing through the spring is also electrically connected to the reinforcing member. The spring is a coil spring sandwiched between the power supply member and the bearing;
The power supply member is plate-shaped, and includes a plate surface facing the bearing across the spring, and a contact portion extending from the plate surface toward the bearing and contacting the reinforcing member.
The image forming apparatus according to claim 1. The reinforcing member is plate-shaped, and the plate surface extends toward the opposite side of the roller along the end surface of the notch,
The image forming apparatus according to claim 2, wherein the contact portion of the power supply member contacts an edge of the reinforcing member located on a side opposite to the roller.   The image forming apparatus according to claim 1, wherein the roller is used for transfer from the photoconductor to the transfer material.   The image forming apparatus according to claim 1, wherein the roller is used for developing the electrostatic latent image.   The image forming apparatus according to claim 1, wherein the roller is used for charging the photoconductor.   The image forming apparatus according to claim 1, wherein the roller is used for cleaning the photoconductor. The frame supports the bearing at both ends of the roller,
The reinforcing member is disposed at both ends of the roller,
The image forming apparatus according to claim 1, wherein the power supply member and the conductive spring are disposed only at the same end of the roller.

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