Transfer apparatus and image forming apparatus

Abstract

This invention discloses a transfer apparatus and an image forming apparatus. The transfer apparatus includes: a transfer member that is energized by a power supply to form a transfer electric field for transferring a developer image onto a recording medium; a transfer roller having a recess that accommodates a holding member, wherein at a transfer position, a transfer electric field is formed between the transfer roller and the transfer member, wherein the holding member holds the end portion of the recording medium; a short-circuit circuit that short-circuits the voltage applied to the transfer member with respect to a reference potential point; and a stop mechanism that activates the short-circuit circuit when the recess enters the transfer position as the transfer roller rotates, and deactivates the short-circuit circuit when the recess leaves the transfer position as the transfer roller rotates.

Description

Technical Field

[0001] This disclosure relates to a transfer apparatus and an image forming apparatus. Background Technology

[0002] Japanese Patent Application Publication No. 58-005769 discloses a technology related to a transfer apparatus for transferring images in the form of a carrier. This prior art includes: a transfer material conveying unit that moves transfer material in a circular motion along a cyclic movement path; a clamping plate mounted on the conveying unit and axially supported on a rotating shaft, rotating relative to a stage member and holding the end edge of the transfer material; and a switching member mounted on the stage member side. The presence of transfer material within the clamp is then detected by partially cutting away the switch member position of the clamping plate. Summary of the Invention

[0003] The transfer apparatus includes: a transfer member which is energized by a power supply to form a transfer electric field that transfers a developer image to a recording medium; and a transfer roller which forms a transfer electric field with the transfer member at a transfer position. For example, if the application of voltage to the transfer member is started and stopped according to an electrical signal, the time taken from sending the electrical signal to generating and eliminating the transfer electric field is [amount missing].

[0004] The objective of this disclosure is to shorten the time required to generate and eliminate the transfer electric field compared to the case where the application of voltage to the transfer component is started and stopped according to an electrical signal.

[0005] According to a first aspect of this disclosure, a transfer apparatus is provided, comprising: a transfer member which is energized by a power supply device to form a transfer electric field for transferring a developer image onto a recording medium; a transfer roller having a recess for accommodating a holding member, wherein at a transfer position, a transfer electric field is formed between the transfer roller and the transfer member, wherein the holding member holds the end portion of the recording medium; a short-circuit circuit that short-circuits the voltage applied to the transfer member to a reference potential point; and a work stop mechanism that activates the short-circuit circuit when the recess enters the transfer position as the transfer roller rotates, and deactivates the short-circuit circuit when the recess disengages from the transfer position as the transfer roller rotates.

[0006] According to the second aspect of this disclosure, the power supply device is capable of switching the voltage applied to the transfer component between a transfer voltage and a standby voltage, wherein the transfer voltage is the voltage that forms a transfer electric field for transferring the developer image onto the recording medium, and the absolute value of the standby voltage is smaller than the absolute value of the transfer voltage. The device switches from the transfer voltage to the standby voltage before the short-circuit circuit operates, and switches from the standby voltage to the transfer voltage before the short-circuit circuit stops operating.

[0007] According to the third aspect of this disclosure, the power supply device is capable of switching the voltage applied to the transfer component between a transfer voltage and a reverse voltage, wherein the transfer voltage is a voltage that forms a transfer electric field for transferring the developer image onto the recording medium, and the polarity of the reverse voltage is opposite to that of the transfer voltage. The device switches from the transfer voltage to the reverse voltage before the short-circuit circuit operates, and switches from the reverse voltage to the transfer voltage before the short-circuit circuit stops operating.

[0008] According to the fourth aspect of this disclosure, the power supply device is capable of switching the voltage applied to the transfer component between the transfer voltage, the reverse voltage, and an intermediate voltage between the transfer voltage and the reverse voltage, switching from the reverse voltage to the intermediate voltage and from the intermediate voltage to the transfer voltage before the short-circuit circuit stops working.

[0009] According to the fifth aspect of this disclosure, the short-circuit circuit is short-circuited to the reference potential point via a resistive element with a resistance value of 1 MΩ or more and 4 MΩ or less.

[0010] According to the sixth aspect of this disclosure, the short-circuit circuit is short-circuited to the reference potential point via a resistive element whose resistance is half the resistance of the transfer component when the transfer electric field is formed.

[0011] According to the seventh aspect of this disclosure, the transfer component rotates around a shaft component made of metal, the power supply device has an application component that applies voltage by contacting the outer peripheral surface of the transfer component, the short-circuit circuit short-circuits the shaft component, and the work stop mechanism has: a grounding component that is configured to be able to contact and separate relative to the shaft component, the grounding component contacting the shaft component to short-circuit the shaft component; and a switching component that switches the contact and separation of the grounding component relative to the shaft component in conjunction with the rotational action of the transfer roller.

[0012] According to the eighth aspect of this disclosure, the transfer roller has: a cylindrical roller body having the recess; and an outer peripheral portion disposed on the outer peripheral surface of the roller body, wherein the work stop mechanism causes the short-circuit circuit to start working and short-circuit when the transfer position is located within the range of the outer peripheral portion.

[0013] According to the ninth aspect of this disclosure, the work stop mechanism stops the short-circuit circuit from operating when the transfer position is located within the outer periphery.

[0014] According to a 10th aspect of this disclosure, a transfer apparatus is provided, comprising: a transfer member that rotates about a shaft member and forms a transfer electric field for transferring a developer image onto a recording medium; an application member that contacts the transfer member and applies a voltage to the transfer member; a grounding member that is disposed in a manner capable of contacting and separating relative to the shaft member, the grounding member contacting the shaft member to ground the transfer member; and a switching member that switches the contact separation of the grounding member relative to the shaft member.

[0015] According to the 11th aspect of this disclosure, the transfer device has a transfer roller that rotates, and the recording medium being transported is wound around the transfer roller. A transfer electric field is formed between the transfer roller and the transfer component. The switching component switches the contact separation of the shaft component of the grounding component in conjunction with the rotation of the transfer roller.

[0016] According to the 12th aspect of this disclosure, the transfer device has a transfer roller that rotates and is wound with a recording medium being conveyed, a transfer electric field is formed between the transfer roller and the transfer member, and the switching member switches the contact separation of the grounding member relative to the shaft member in conjunction with the rotation of the transfer roller.

[0017] According to the 13th aspect of this disclosure, the switching component includes: a rotating shaft portion disposed in a U-shaped bend when viewed from the axial direction of the shaft component, the rotating shaft portion extending along the axial direction; a contact portion disposed on one side of the U-shape, rotating about the rotating shaft portion and contacting the outer peripheral surface of the transfer cylinder; and a support portion disposed on the other side of the U-shape, rotating about the rotating shaft portion and supporting the grounding component.

[0018] According to the 14th aspect of this disclosure, the transfer device has a conveying member having a holding member that holds the end of the recording medium, and in a state where the holding member is opposite to the transfer member, the switching member causes the grounding member to contact the shaft member.

[0019] According to the 15th aspect of this disclosure, a recess is formed on the outer peripheral surface of the transfer cylinder, the recess extending along the axial direction, and the holding member is disposed in the recess. The transfer cylinder has a recording medium wound on its outer peripheral surface, which is held by the holding member disposed in the recess. When the contact portion is in contact with the outer peripheral surface of the transfer cylinder, the switching member separates the grounding member from the shaft member. When the contact portion is disposed in the recess of the transfer cylinder, the switching member contacts the grounding member with the shaft member. Before the portion of the wound recording medium on the outer peripheral surface of the transfer cylinder is opposite to the transfer member, the contact portion disposed in the recess contacts the outer peripheral surface of the transfer cylinder.

[0020] According to the 16th aspect of this disclosure, a transfer apparatus is provided, comprising: a transfer member that rotates about a shaft member and is subjected to a voltage to form a transfer electric field for transferring a developer image onto a recording medium; a transfer roller that is opposite to and rotates relative to the transfer member, forming a transfer electric field between the transfer roller and the transfer member; a grounding member that is disposed in a manner that allows it to contact and separate relative to the shaft member, the grounding member contacting the shaft member to ground the transfer member; and a switching member that switches the contact and separation of the grounding member relative to the shaft member in conjunction with the rotational action of the transfer roller.

[0021] According to the 17th aspect of this disclosure, the transfer device has a conveying member having a holding member that holds the end of the recording medium and conveys the recording medium. In a state where the transfer member is opposite to the holding member, the switching member causes the grounding member to contact the shaft member.

[0022] According to the 18th aspect of this disclosure, a recess is formed on the outer peripheral surface of the transfer cylinder, the recess extends axially along the shaft member, and the holding member is disposed in the recess. By setting a portion of the transfer cylinder as a cam surface, the switching member switches in conjunction with the rotation of the transfer cylinder whether the transfer member is grounded through the grounding member.

[0023] According to the 19th aspect of this disclosure, the cam surface is formed in the axial direction at the end of the transfer cylinder, and the shape of the cam surface is different from that of the other parts in the axial direction.

[0024] According to the 20th aspect of this disclosure, when the recording medium being conveyed is wound on the transfer cylinder and the transfer member is facing the portion of the wound recording medium in the transfer cylinder, the switching member causes the grounding member to separate from the shaft member.

[0025] According to the 21st aspect of this disclosure, the switching member has: a rotating shaft portion extending axially along the shaft portion; and a contact portion rotating about the rotating shaft portion and contacting the outer peripheral surface of the transfer cylinder. When the contact portion is in contact with the outer peripheral surface of the transfer cylinder, the switching member separates the grounding member from the shaft portion. When the contact portion is disposed within the recess, the switching member contacts the grounding member with the shaft portion. Before the transfer member reaches the portion of the recording medium wound on the outer peripheral surface of the transfer cylinder, the contact portion disposed in the recess contacts the outer peripheral surface of the transfer cylinder.

[0026] According to the 22nd aspect of this disclosure, an image forming apparatus is provided, comprising: an image forming section that forms a developer image; and the aforementioned transfer apparatus that transfers the developer image formed by the image forming section onto a recording medium.

[0027] (Effect)

[0028] According to the first scheme, compared with the case where the application of voltage to the transfer component is started and stopped according to an electrical signal, the time required to generate and eliminate the transfer electric field can be shortened.

[0029] According to the second scheme, compared with the case where the transfer voltage is maintained even when the short-circuit circuit is operating, the surge current to the short-circuit circuit can be suppressed.

[0030] According to the third scheme, compared with the case where the transfer voltage is maintained even when the short-circuit circuit is operating, the surge current to the short-circuit circuit can be suppressed.

[0031] According to the fourth scheme, compared with the case of directly switching from reverse voltage to transfer voltage, the time required to generate the transfer electric field can be shortened.

[0032] According to the fifth scheme, compared with the case of short-circuiting to the reference potential point via a resistive element with a resistance value of less than 1MΩ, the surge current to the short-circuit circuit can be suppressed.

[0033] According to the sixth scheme, compared with the case where a resistive element with the same resistance value as the transfer component when forming the transfer electric field is short-circuited to the reference potential point, the amplitude of current variation can be suppressed.

[0034] According to the seventh scheme, compared with the case where the short-circuit circuit is directly short-circuited from the power supply device to the reference potential point, the surge current to the short-circuit circuit can be suppressed.

[0035] According to the eighth solution, compared to the case where the short circuit circuit starts working and short circuits when the transfer position is not in the outer periphery, leakage current from the transfer component to the roller body can be prevented.

[0036] According to the ninth solution, compared to the case where the short-circuit circuit stops working when the transfer position is not at the outer periphery, leakage current from the transfer component to the roller body can be prevented.

[0037] According to the 10th scheme, compared with the case where the voltage applied to the transfer component is terminated based on an electrical signal, the time required to eliminate the transfer electric field can be shortened.

[0038] According to the 11th solution, a transfer electric field can be generated in conjunction with the rotation of the transfer roller, and the transfer electric field can be eliminated.

[0039] According to the 12th solution, the number of components can be reduced compared to the case where a component specifically designed to form the cam surface is provided.

[0040] According to the 13th solution, compared to the seesaw type where the switching component extends to one side and the other side relative to the rotation axis, the length of the switching component in the length direction can be shortened.

[0041] According to the 14th solution, compared with the case where the grounding component is separated from the shaft component while the holding component and the transfer component are facing each other, the flow of current from the transfer component to the holding component can be suppressed.

[0042] According to the 15th embodiment, a transfer electric field can be formed before the wound portion of the wound recording medium on the outer peripheral surface of the transfer cylinder is opposite to the transfer component.

[0043] According to the 16th solution, compared to the case where the application of voltage to the transfer component is terminated based on an electrical signal, the time required to eliminate the transfer electric field in conjunction with the rotation of the transfer roller can be shortened.

[0044] According to the 17th solution, compared with the case where the grounding component and the shaft component are separated when the transfer component and the holding component are facing each other, the flow of current from the transfer component to the holding component can be suppressed.

[0045] According to the 18th solution, the number of components can be reduced compared to the case where a component specifically designed to form the cam surface is provided.

[0046] According to the 19th embodiment, it is possible to switch whether the transfer component is grounded via the grounding component in the axial direction regardless of the shape of the central side portion of the transfer roller.

[0047] According to the 20th embodiment, compared to the case where the grounding component contacts the shaft component when the transfer component is opposite to the front end portion of the recording medium wound on the transfer cylinder, the area on which the developer image can be transferred on the recording medium can be increased.

[0048] According to the 21st embodiment, a developer image can be transferred from the front end portion of the recording medium wound around the transfer cylinder.

[0049] According to the 22nd solution, compared with a transfer device that starts and stops applying voltage to the transfer component based on an electrical signal, the amount of blank space at the end of the recording medium can be reduced. Attached Figure Description

[0050] Figure 1 This is a perspective view showing the switching unit and other components of the transfer apparatus according to the first embodiment of this disclosure.

[0051] Figure 2 This is a perspective view showing the secondary transfer roller, the relative roller, and the switching unit, etc., of the transfer apparatus according to the first embodiment of this disclosure.

[0052] Figure 3 (A), (B), and (C) are operation diagrams illustrating the operation of transferring sheet components through the transfer apparatus according to an embodiment of the present disclosure.

[0053] Figure 4 (A) and (B) are operation diagrams showing the switching operation of the switching unit of the transfer apparatus according to the embodiments of this disclosure.

[0054] Figure 5 (A) and (B) are operation diagrams showing the switching operation of the switching unit of the transfer apparatus according to the embodiments of this disclosure.

[0055] Figure 6 This is a perspective view showing the chain clamp of the transfer apparatus according to the first embodiment of the present disclosure.

[0056] Figure 7 This is a cross-sectional view of the transfer cylinder orthogonal to the axial direction according to the first embodiment of this disclosure.

[0057] Figure 8 (A) is a schematic diagram showing the secondary transfer roller entering and exiting the recess of the transfer cylinder of the transfer apparatus according to the embodiments of the present disclosure. Figure 8 (B) is Figure 8 An enlarged view of part B of (A).

[0058] Figure 9 This is a front view of the switching section of the transfer apparatus according to the first embodiment of this disclosure.

[0059] Figure 10 This is a wiring diagram of the application circuit and short-circuit circuit of the transfer apparatus according to the first embodiment of this disclosure.

[0060] Figure 11 yes Figure 10 The equivalent circuit diagram of the wiring diagram.

[0061] Figure 12 This is a timing diagram showing the voltage supplied by the power supply device of the transfer apparatus according to the first embodiment of the present disclosure.

[0062] Figure 13 This is an explanatory diagram illustrating the timing of switching the voltage supplied by the power supply device of the transfer apparatus according to the first embodiment of this disclosure.

[0063] Figure 14 This is a schematic diagram showing the overall structure of the image forming apparatus according to the first embodiment of this disclosure.

[0064] Figure 15 This is a perspective view showing the fixing apparatus of the image forming apparatus according to the first embodiment of the present disclosure.

[0065] Figure 16 This is a perspective view showing the switching unit and other components of the transfer apparatus according to the second embodiment of this disclosure.

[0066] Figure 17 This is a perspective view showing the secondary transfer roller, the opposing roller, and the switching unit, etc., of a transfer device with a deformation mode. Detailed Implementation

[0067] <First Embodiment>

[0068] according to Figures 1 to 15 An example of the transfer apparatus and image forming apparatus according to the first embodiment of this disclosure will be described. In the figures, arrow H indicates the vertical direction of the apparatus, arrow W indicates the width direction of the apparatus (horizontal direction), and arrow D indicates the depth direction of the apparatus (horizontal direction). Figure 14 This is a schematic diagram showing the overall structure of the image forming apparatus. Therefore, there are parts that do not precisely correspond to the detailed diagrams shown in other figures.

[0069] (Image forming apparatus 10)

[0070] Figure 14 The image forming apparatus 10 shown in this embodiment is a sheet component P (refer to) that serves as a recording medium. Figure 3 An electronic photographic image forming apparatus that forms an image of toner on a paper. The image forming apparatus 10 includes a paper feeding mechanism 48, an image forming unit 12, a fixing device 100, and a paper discharge mechanism 56, etc.

[0071] [Paper supply organization 48]

[0072] The paper feeding mechanism 48 has the function of conveying the sheet component P, which is housed in a receiving section (not shown), to the chain gripper 66.

[0073] The paper feeding mechanism 48 consists of an annular conveyor belt 48B wound around a pair of rollers 48A. Furthermore, the conveyor belt 48B transports the sheet component P, which is then transferred to the holding component 76 (see reference 76). Figure 6 ).

[0074] [Image forming unit 12]

[0075] The image forming unit 12 has the function of forming an image on the sheet member P by electrophotography. The image forming unit 12 includes: a toner image forming unit 20 for forming a toner image; and a transfer device 30 for transferring the toner image formed by the toner image forming unit 20 onto the sheet member P. Furthermore, the toner image is an example of a developer image, and the toner image forming unit is an example of a developer image forming unit.

[0076] The toner image forming unit 20 has multiple units to form a toner image for each color. In the image forming unit 12 of this embodiment, there is a toner image forming unit 20 with a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K). Furthermore, the (Y), (M), (C), and (K) following the symbols denote structural portions corresponding to each color. And, without distinguishing between yellow (Y), magenta (M), cyan (C), and black (K), the (Y), (M), (C), and (K) following the symbols are omitted in the description.

[0077] -Toner Image Forming Unit 20-

[0078] The toner image forming units 20Y, 20M, 20C, and 20K for each color are substantially identical except for the toner used. Therefore, they will be described without distinguishing between the colors. These toner image forming units 20Y, 20M, 20C, and 20K are arranged along the horizontal portion above the transfer belt 31 that constitutes the transfer apparatus 30.

[0079] The toner image forming unit 20 includes a photosensitive drum 21 that rotates in the direction of arrow A01 in the figure, and an electric charge device 22 that charges the photosensitive drum 21. Furthermore, the toner image forming unit 20 includes an exposure apparatus 23 that exposes the photosensitive drum 21 charged by the electric charge device 22 to form an electrostatic latent image, and a developing apparatus 24 that develops the electrostatic latent image to form a toner image.

[0080] -Transfer device 30-

[0081] The transfer apparatus 30 has the function of performing a first transfer by overlapping the toner image of the photosensitive drum 21 of the toner image forming section 20 of each color with an intermediate transfer body, and then transferring the overlapped toner image a second time onto the sheet member P. The transfer apparatus 30 includes, as an example, a transfer belt 31, multiple rollers 32, a primary transfer roller 33, a secondary transfer roller 34, and a transfer cylinder 36. Furthermore, the transfer apparatus 30 includes an application roller 44 for applying voltage to the secondary transfer roller 34, and a chain clamp 66 for conveying the sheet member P. The transfer apparatus 30 also includes a grounding unit 180 (see reference) for grounding the secondary transfer roller 34. Figure 1 ).

[0082] The transfer belt 31 is endless and is wound around a plurality of rollers 32 and a secondary transfer roller 34 in an inverted triangular shape. The transfer belt 31 is wound in the direction of arrow B by being rotated by at least one of the rollers 32.

[0083] The primary transfer roller 33 is positioned on the side opposite to the photosensitive drums 21 of each color, separated by the transfer belt 31. Furthermore, the primary transfer roller 33 has the function of transferring the toner image formed on the photosensitive drum 21 to the transfer belt 31 at the primary transfer position T between the photosensitive drum 21 and the primary transfer roller 33.

[0084] The transfer roller 36 has a circular cross-section and is positioned on the opposite side of the secondary transfer roller 34, separated by the transfer belt 31. This transfer roller 36 has the function of transferring the toner image transferred onto the transfer belt 31 to the sheet component P at a secondary transfer position NT between the transfer belt 31 and the transfer roller 36.

[0085] The chain gripper 66 includes: a pair of chains 72; sprockets 71 and 73; and a gripping unit 68 having a gripping member 76 that grips the end of the sheet member P (see reference). Figure 6 ).

[0086] like Figure 6 As shown, a pair of chains 72 are separately arranged in the depth direction of the device, and the chains 72 are formed without ends. Furthermore, as... Figure 2 As shown, a pair of chains 72 are arranged on one end and the other end of the transfer cylinder 36 along the axial direction and are wound on a pair of sprockets 73 with the axial direction as the depth direction of the device.

[0087] like Figure 15 As shown, a pair of chains 72 are disposed on one end and the other end of the pressure roller 140 described later, and are wound on a pair of sprockets 71 with the axial direction as the depth direction of the device.

[0088] like Figure 14As shown, the chain 72 is wound around the sprockets 71 located at both ends of the pressure roller 140 and the sprockets 73 located at both ends of the transfer roller 36. Furthermore, in this structure, by transmitting rotational force to any one of the sprockets 71 and 73, the pair of chains 72 move in the direction of arrow C in the figure, moving from the sprocket 73 side towards the sprocket 71 side. In this embodiment, the rotational force is transmitted to the sprocket 73.

[0089] Multiple gripping units 68 are provided, arranged at predetermined intervals along the circumference (circumferential direction) of the chain 72. Furthermore, as... Figure 6 As shown, the gripping unit 68 extends along the depth direction of the device, and the portions on both sides of the gripping unit 68 in the depth direction of the device are respectively mounted on a pair of chains 72. Moreover, the gripping unit 68 has a gripping member 76 made of metal that grips the end of the sheet member P.

[0090] In this structure, the chain gripper 66 conveys the sheet component P along the circumferential direction of a pair of chains 72.

[0091] Furthermore, descriptions of the secondary transfer roller 34, application roller 44, chain clamp 66, and transfer cylinder 36 of the transfer device 30 will be provided later.

[0092] [Fixing device 100]

[0093] Figure 14 The fixing device 100 shown has the function of fixing the toner image transferred to the sheet component P by the transfer device 30 onto the sheet component P.

[0094] like Figure 15 As shown, the fixing device 100 includes: a heating roller 130 that contacts the conveyed sheet component P to heat the sheet component P; a pressure roller 140 that applies pressure to the sheet component P toward the heating roller 130; and a driven roller 150 that rotates driven by the heating roller 130 and heats the heating roller 130.

[0095] Furthermore, the fixing device 100 includes: a support member 156 that contacts the shaft portion 148 of the pressure roller 140 to support the pressure roller 140; and a force application member 158 that applies force to the pressure roller 140 toward the heating roller 130 via the support member 156.

[0096] In this structure, the driven roller 150 rotates following the rotating heating roller 130. Furthermore, the sheet component P, which is transferred with a toner image, is held and conveyed by the heating roller 130 and the pressure roller 140, and the toner image is heated and fixed onto the sheet component P.

[0097] [Paper stacking mechanism 56]

[0098] Figure 14 The paper discharge mechanism 56 shown has the function of discharging the sheet component P, on which a toner image has been fixed by the fixing device 100, to a discharge section (not shown). Furthermore, the paper discharge mechanism 56 has the function of receiving the released holding member 76 (see reference 76). Figure 6 The sheet component P is held and conveyed. The paper discharge mechanism 56 is composed of an annular conveyor belt 56B wound on a pair of rollers 56A. The sheet component P is conveyed by the conveyor belt 56B and discharged to a discharge section (not shown).

[0099] (Summary of image formation process)

[0100] exist Figure 14 In the image forming apparatus 10 shown, a toner image is formed on the sheet component P as follows: First, the charge carriers 22 of each color uniformly charge the surface of the photosensitive drum 21 of each color with a predetermined potential. Next, the exposure apparatus 23 irradiates the charged surface of the photosensitive drum 21 of each color with exposure light according to image data input from the outside to form an electrostatic latent image.

[0101] Thus, an electrostatic latent image corresponding to the image data is formed on the surface of each photosensitive drum 21. Furthermore, the developing apparatus 24 for each color develops the electrostatic latent image to visualize it as a toner image. Then, the primary transfer roller 33 of the transfer apparatus 30 transfers the toner image formed on the surface of each color photosensitive drum 21 onto the transfer belt 31 at the primary transfer position T.

[0102] Therefore, the sheet component P, which is not shown in the receiving section, is conveyed by the paper feeding mechanism 48 and handed over to the chain gripper 66, and then conveyed by the chain gripper 66. The sheet component P conveyed by the chain gripper 66 is sent to the secondary transfer position NT where the transfer belt 31 contacts the transfer roller 36. At the secondary transfer position NT, the sheet component P is held and conveyed by the transfer belt 31 and the transfer roller 36, whereby the toner image on the surface of the transfer belt 31 is transferred to the surface of the sheet component P.

[0103] The fixing device 100 fixes the toner image transferred to the surface of the sheet component P onto the sheet component P, and the sheet component P is then fed to the paper discharge mechanism 56. The sheet component P fed to the paper discharge mechanism 56 is discharged to a discharge section (not shown).

[0104] (Main structural components)

[0105] Next, the chain clamp 66, secondary transfer roller 34, application roller 44, transfer cylinder 36, application circuit 400, short circuit circuit 500 and grounding unit 180 of the transfer device 30 will be described.

[0106] [Chain gripper 66]

[0107] As mentioned above, Figure 15 The chain gripper 66 shown includes: a pair of chains 72; sprockets 71 and 73; and a gripping unit 68 (see reference) having a gripping member 76 that grips the end of the sheet member P. Figure 6 Chain gripper 66 is an example of a conveying component.

[0108] like Figure 6 As shown, the gripping unit 68 includes: a plate portion 80 extending in the depth direction of the device; a pair of support plates 82 supporting the plate portion 80; and shaft members 84 extending in the depth direction of the device and having their ends respectively mounted on the chain 72. Furthermore, the gripping unit 68 includes a gripping member 76 that grips the end of the sheet member P between itself and the plate portion 80.

[0109] - Plate 80, Support Plate 82, Shaft Component 84 -

[0110] like Figure 6 As shown, the plate portion 80 is made of stainless steel and is positioned between a pair of chains 72. Furthermore, when viewed from the depth direction of the device, the plate portion 80 is inclined relative to the sheet conveying direction such that the upstream portion is closer to the sheet component P than the downstream portion.

[0111] The support plates 82 are made of stainless steel and are positioned at both ends of the plate portion 80, with the thickness direction serving as the depth direction of the device. Furthermore, a pair of support plates 82 are mounted on each end of the plate portion 80, and the pair of support plates 82 support the plate portion 80. A circular through hole 82a is formed in each support plate 82.

[0112] The shaft component 84 is made of stainless steel and extends along the depth direction of the device, positioned downstream of the plate portion 80 in the sheet conveying direction. Furthermore, the shaft component 84 passes through through holes 82a formed in the support plate 82. Both ends of the shaft component 84 are respectively mounted to a pair of chains 72.

[0113] -Holding component 76-

[0114] like Figure 6 As shown, multiple gripping members 76 are provided and installed on the shaft member 84 at predetermined intervals along the depth direction of the device. The gripping member 76 has: a main body portion 86 having a through hole 86a for the shaft member 84 to pass through; and a contact portion 88 that contacts the sheet member P.

[0115] The main body 86 is made of aluminum, and when viewed from the depth direction of the device, the downstream portion of the main body 86 in the sheet conveying direction is arc-shaped. Furthermore, a protrusion 86b is formed on the upstream side of the main body 86 in the sheet conveying direction and on the outer side of the annular chain 72 (i.e., the side opposite to the side surrounded by the annular chain 72 when viewed from the depth direction of the device), protruding towards the plate portion 80. Moreover, when viewed from the protruding direction, the protrusion 86b is rectangular.

[0116] The contact portion 88 is a plate component made of stainless steel, installed on the outer side of the protrusion 86b facing the endless chain 72. Furthermore, the contact portion 88 extends from the protrusion 86b toward the plate portion 80 and contacts the plate portion 80 from the outer side of the loop chain 72.

[0117] In this structure, the shaft member 84 rotates via a cam mechanism (not shown), and the contact portion 88 is pressed from the outside of the endless chain 72 toward the plate portion 80, thus contacting the plate portion 80, and then separating from the plate portion 80. In this way, the end of the sheet member P is held by the holding member 76, and the holding is released.

[0118] [Secondary transfer roller 34]

[0119] like Figure 2 As shown, the secondary transfer roller 34 extends along the depth direction of the device, and the transfer belt 31 is wound on the secondary transfer roller 34. Furthermore, the secondary transfer roller 34 has a shaft member 34a and a cylindrical roller portion 34b through which the shaft member 34a passes. The secondary transfer roller 34 is an example of a transfer component. And, the depth direction of the device is an example of an axial direction.

[0120] Shaft component 34a is a shaft made of stainless steel, and its two ends are supported by bearings on a frame (not shown). Roller portion 34b is made of rubber and is mounted on shaft component 34a so as to rotate together with shaft component 34a. Shaft component 34a is preferably made of a conductive material, more preferably of metal, and even more preferably of stainless steel.

[0121] In this structure, the secondary transfer roller 34 rotates driven by the surrounding transfer belt 31.

[0122] [Applying roller 44]

[0123] like Figure 2 As shown, the diameter of the application roller 44, which is an example of an application component, is smaller than the diameter of the secondary transfer roller 34, and it is positioned on the side opposite to the transfer belt 31, separated from the secondary transfer roller 34. Furthermore, the application roller 44 extends along the depth direction of the device and contacts the outer peripheral surface of the secondary transfer roller 34.

[0124] In this structure, the application roller 44 is rotated following the rotation of the secondary transfer roller 34. Furthermore, it is powered by the power supply device 410 (see reference 410). Figure 10 Power is supplied to the shaft of the application roller 44, and the application roller 44 applies voltage to the secondary transfer roller 34. As a result, a transfer electric field is formed at the secondary transfer position NT between the secondary transfer roller 34 and the transfer cylinder 36 for transferring the toner image on the transfer belt 31 to the sheet component P.

[0125] [Transfer Roller 36]

[0126] like Figure 2 As shown, the transfer roller 36 is positioned on the opposite side of the secondary transfer roller 34, separated from the transfer belt 31. The transfer roller 36 extends along the depth direction of the device.

[0127] The transfer roller 36 has a roller portion 174 and a pair of shaft portions 176 protruding from both ends of the roller portion 174 in the depth direction of the device. Furthermore, the roller portion 174 protrudes from the roller portion 34b of the secondary transfer roller 34 in the depth direction of the device. The aforementioned sprockets 73 are respectively mounted on the pair of shaft portions 176.

[0128] like Figure 3 As shown in (A), a recess 178 is formed in the roller portion 174 of the transfer roller 36, on which a holding member 76 is disposed. The recess 178 extends from one end of the roller portion 174 along the depth direction of the device to the other end.

[0129] In this structure, such as Figure 3 As shown in (A), if the holding member 76 holding the end of the sheet member P reaches the rotating transfer cylinder 36, it is disposed in the recess 178 of the roller portion 174. Moreover, as Figure 3 As shown in (B), the sheet component P, held at the end by the holding member 76 and conveyed, is wound around the rotating transfer cylinder 36 while being transported, and is clamped by the roller 174 and the transfer belt 31 at the secondary transfer position. In this way, the sheet component P is conveyed while being wound around the transfer cylinder 36. That is, the transfer cylinder 36 functions as a support unit supporting the sheet component P.

[0130] Then, the toner image on the transfer belt 31 is transferred to the sheet component P at the secondary transfer position NT by the transfer electric field.

[0131] Moreover, such as Figure 3 As shown in (C), the holding member 76 disposed in the recess 178 of the roller 174 disengages from the recess 178 of the rotating transfer roller 36, and the chain clamp 66 conveys the sheet member P downstream in the sheet conveying direction.

[0132] like Figure 7As shown, the roller portion 174 of the transfer roller 36 is configured to have: a roller body 252 made of a metal such as aluminum; and a sheet-like jacket member 260, which is an example of being wound around the outer periphery of the roller body 252. The aforementioned recess 178 is formed along the axial direction on a portion of the outer peripheral surface of the roller body 252.

[0133] The jacket component 260 is made of resin and has a higher volume resistivity than the roller body 252, which is made of metal. The jacket component 260 has a base layer 262 that is non-adhesively wound around the roller body 252, and a surface layer 264 that is adhesively wound around the outer periphery of the base layer 262. Roller side blocks 256 are provided at both circumferential ends of the bottom wall 255 within the recess 178. Furthermore, the ends 262A of the base layer 262 of the jacket component 260 are threadedly fastened to the roller side blocks 256, thereby allowing for detachable installation on the roller body 252. In other words, the jacket component 260 can be replaced.

[0134] like Figure 8 As shown in (A), one end 261 of the jacket member 260 is flush or substantially flush with the wall surface 178A of one end side of the recess 178. Furthermore, the other end 263 of the jacket member 260 is flush or substantially flush with the wall surface 178B of the other end side of the recess 178.

[0135] like Figure 8 (A) and Figure 8 As shown in (B), the other end 263 of the jacket member 260 is formed with an inclined surface 263A that thins towards the end side. The rear end of the inclined surface 263A is designated as the inclined end 263B.

[0136] In addition, Figure 8 The diagram in (A) shows two secondary transfer rollers 34, the reasons for which will be explained later.

[0137] [Grounding Unit 180]

[0138] like Figure 1 As shown, the grounding unit 180, as an example of a work stop mechanism, is disposed on the front side of the device in the depth direction relative to the roller portion 34b of the secondary transfer roller 34. The grounding unit 180 includes: a grounding member 182, which contacts the shaft member 34a of the secondary transfer roller 34 to ground the secondary transfer roller 34; and a switching member 190, which switches the contact separation of the grounding member 182 relative to the shaft member 34a.

[0139] The switching component 190 is formed in a U-shape with the end side open in the upstream direction of the sheet conveying direction when viewed from the width direction of the device, and has a rotating shaft portion 192, a main body portion 194 and a contact roller 196.

[0140] The main body 194 is made of resin and has a pair of straight portions 194a and 194b and a curved portion 194c connecting the base ends of the pair of straight portions 194a and 194b. When viewed from the depth direction of the device, the straight portion 194a is positioned between the transfer roller 36 and the shaft member 34a, and when viewed from the depth direction of the device, the straight portion 194b is positioned on the opposite side of the straight portion 194a, separated by the shaft member 34a. The straight portion 194b is an example of a support portion.

[0141] The rotating shaft 192 is supported by a frame (not shown) and extends through the curved portion 194c of the main body 194 with the device depth direction as the axis. Furthermore, the rotating shaft 192 supports the main body 194 so that it can rotate.

[0142] The straight section 194b supports the grounding member 182. Specifically, the straight section 194b supports the grounding member 182 by installing the grounding member 182 on the end side of the straight section 194b and on the side of the shaft member 34a.

[0143] The grounding component 182 is made of steel and is connected to a grounding wire (not shown). Thus, the secondary transfer roller 34 is grounded through contact between the grounding component 182 and the shaft component 34a. Furthermore, the grounding component 182 is preferably a conductor, more preferably a metal product, and even more preferably made of steel.

[0144] The contact roller 196 is mounted at the end of the straight section 194a and rotates axially in the direction of device depth. Furthermore, the contact roller 196 is subjected to force on the outer peripheral surface of the roller section 174 of the transfer cylinder 36 by a force-applying member (not shown) disposed on the rotating shaft section 192. The contact roller 196 is an example of a contact section.

[0145] Furthermore, with the contact roller 196 in contact with the outer peripheral surface of the roller portion 174 of the transfer roller 36, the grounding member 182 separates from the shaft member 34a (see reference). Figure 4 (A)). Moreover, with the contact roller 196 disposed within the recess 178 of the transfer roller 36, the grounding member 182 contacts the shaft member 34a (see reference). Figure 4 (B)). In this way, the outer peripheral surface of the roller portion 174 and the recess 178 function as cam surfaces, and the contact roller 196 functions as a cam follower.

[0146] like Figure 4 (A) and Figure 4As shown in (B), specifically, the contact roller 196, which contacts the outer peripheral surface of the roller portion 174, reaches the downstream end of the rotational direction of the recess 178 before the secondary transfer roller 34 reaches the downstream end of the rotational direction of the recess 178. In other words, the contact roller 196, which contacts the outer peripheral surface of the roller portion 174, reaches the downstream end of the rotational direction of the recess 178 before the secondary transfer position NT reaches the downstream end of the rotational direction of the recess 178.

[0147] Here, when viewed from the depth of the device, the intersection of the lower line and the outer peripheral surface of the secondary transfer roller 34 is set as intersection point K01 (refer to...). Figure 4 (A) The line is the line connecting the rotation center of the secondary transfer roller 34 and the rotation center of the transfer roller 36 (lines S1 to S4 described later). "Before the secondary transfer roller 34 reaches the downstream end of the rotation direction of the recess 178" and "before the secondary transfer position NT reaches the downstream end of the rotation direction of the recess 178" mean: before the intersection K01 reaches the downstream end of the rotation direction of the recess 178.

[0148] like Figure 5 (A) and Figure 5 As shown in (B), the contact roller 196, which reaches the downstream end of the rotational direction of the recess 178, reaches the outer peripheral surface of the transfer cylinder 36 after the holding member 76 passes the secondary transfer roller 34. In other words, the contact roller 196, which reaches the downstream end of the rotational direction of the recess 178, reaches the outer peripheral surface of the transfer cylinder 36 after the holding member 76 passes the secondary transfer position NT.

[0149] "After the holding component 76 passes the secondary transfer roller 34" and "After the holding component 76 passes the secondary transfer position NT" mean that the holding component 76 has passed the intersection point K01 when viewed from the depth direction of the device.

[0150] Furthermore, the wound portion of the sheet member P on the outer peripheral surface of the transfer cylinder 36 reaches the secondary transfer roller 34 after the contact roller 196 reaches the outer peripheral surface of the transfer cylinder 36. In other words, the wound portion of the sheet member P on the outer peripheral surface of the transfer cylinder 36 reaches the secondary transfer position NT after the contact roller 196 reaches the outer peripheral surface of the transfer cylinder 36. Moreover, in other words, the contact roller 196 disposed in the recess 178 contacts the outer peripheral surface of the transfer cylinder 36 before the secondary transfer roller 34 reaches the portion of the sheet member P on the outer peripheral surface of the transfer cylinder 36. In addition, the area of ​​the sheet member P from the portion held by the holding member 76 to the portion wound on the outer peripheral surface of the transfer cylinder 36 is not included in the wound portion.

[0151] "Before the portion of the secondary transfer roller 34 that has the sheet component P wound on its outer circumferential surface in the transfer cylinder 36" means: before the intersection point K01 reaches the portion of the transfer cylinder 36 that has the sheet component P wound on its outer circumferential surface when viewed from the depth direction of the device.

[0152] Then, with the secondary transfer roller 34 and the portion of the transfer roller 36 in which the sheet member P is wound facing each other, the grounding member 182 separates from the shaft member 34a. In other words, with the secondary transfer roller 34 and the portion of the transfer roller 36 in which the sheet member P is wound facing each other, a transfer electric field is generated at the secondary transfer position NT.

[0153] "The state in which the secondary transfer roller 34 and the portion of the transfer roller 36 in which the sheet component P is wound are opposite each other" refers to the state in which the intersection point K01 and the portion of the transfer roller 36 in which the sheet component P is wound are opposite each other when viewed from the depth direction of the device.

[0154] like Figure 9 As shown, a resistor element 502 is provided on the main body 194 of the switching component 190 of the grounding unit 180. Furthermore, the grounding component 182 is connected to the reference potential point G (see reference 180) via the resistor element 502. Figure 10 as well as Figure 11 Electrical connection. Additionally, in this embodiment, the grounding component 182 is electrically connected to the rotating shaft 192 via a resistor element 502, and the rotating shaft 192 is connected to the reference potential point G (refer to...). Figure 10 as well as Figure 11 Electrical connection.

[0155] Furthermore, the resistance value of the resistive element 502 is set in the range of 1 MΩ or more and 4 MΩ or less. It is also set to approximately half the volume resistance value of the secondary transfer roller 34 when the transfer electric field is formed. In this embodiment, a 2.5 MΩ resistive element is used for the resistive element 502.

[0156] like Figure 4 (A) and Figure 5 As shown in (B), with the contact roller 196 in contact with the outer peripheral surface of the roller portion 174 of the transfer cylinder 36, the grounding member 182 separates from the shaft member 34a. As a result, the current generated by the voltage applied to the secondary transfer roller 34 by the application roller 44 flows to the transfer cylinder 36 side, forming a transfer electric field at the secondary transfer position NT.

[0157] On the other hand, such as Figure 4 (B) and Figure 5As shown in (A), with the contact roller 196 disposed within the recess 178, the grounding member 182 contacts the shaft member 34a. Consequently, current generated by the voltage applied to the secondary transfer roller 34 by the application roller 44 flows towards the grounding member 182, via the resistor element 502 (see reference 1). Figure 9 And compared with the reference potential point G (reference) Figure 10 as well as Figure 11 A short circuit eliminates the transfer electric field formed at the secondary transfer position NT.

[0158] Thus, the switching component 190 switches the current path from the secondary transfer roller 34 to the short-circuit circuit 500 (described later) (see reference). Figure 10 as well as Figure 11 The path switching component functions as described above. Furthermore, the timing of switching to short-circuit circuit 500 will be explained later.

[0159] in addition, Figure 4 (A) Figure 4 (B) Figure 5 (A) and Figure 5 In (B), lines S1, S2, S3, and S4 indicate the positions corresponding to the secondary transfer position NT. Specifically, the intersection point K01, which is the point where these lines intersect with the outer peripheral surface of the secondary transfer roller 34 (see reference...). Figure 4 (A) is the secondary transfer position NT.

[0160] [Applying circuit 400 and short-circuit circuit 500]

[0161] Figure 10 This is a wiring diagram of the application circuit 400 that applies high voltage to the secondary transfer roller 34 and the short-circuit circuit 500. Figure 11 yes Figure 10 The equivalent circuit diagram.

[0162] The application circuit 400 is configured to include a power supply device 410, an application roller 44, and a secondary transfer roller 34. The application roller 44 has a shaft member 44a and a cylindrical roller portion 44b through which the shaft member 44a passes. As described above, by supplying power from the power supply device 410 to the shaft member 44a of the application roller 44, a voltage is applied to the secondary transfer roller 34, and at the secondary transfer position NT (refer to...). Figure 4 (etc.) to form a transfer electric field.

[0163] The short-circuit circuit 500 is configured to include the aforementioned grounding component 182 and resistive element 502. As described above, the short-circuit circuit 500 is switched to short-circuit circuit 500 by contacting the shaft component 34a with the grounding component 182, and short-circuited to the reference potential point G via the grounding component 182 and resistive element 502, at the secondary transfer position NT (refer to...). Figure 4 The transfer electric field formed by (etc.) is eliminated.

[0164] [Power Supply Unit 410]

[0165] like Figure 12 As shown, the power supply device 410 is capable of supplying power to the application roller 44 (see reference). Figure 10 The voltage is switched between transfer voltage TV, reverse voltage GV, and intermediate voltage CV. Additionally, Figure 12 This is a timing diagram showing the voltage switching moments, which will be discussed later.

[0166] The transfer voltage TV is at the secondary transfer position NT (refer to...). Figure 4 The voltage at which the transfer electric field is formed (etc.). The reverse voltage GV is a voltage with the opposite polarity to the transfer voltage TV and a smaller absolute value. The intermediate voltage CV is a voltage with the same polarity as the transfer voltage TV and between the transfer voltage TV and the reverse voltage GV. In this embodiment, the intermediate voltage CV is set to CV = TV / 2, but it is not limited to this.

[0167] The switching of the transfer voltage TV, reverse voltage GV, and intermediate voltage CV of the power supply unit 410 is controlled by the control unit 402 (see reference). Figure 10 The switching of the transfer voltage TV, reverse voltage GV, and intermediate voltage CV is performed based on a reference signal used at various times in conjunction with the overall image forming apparatus 10. That is, the switching is performed after a set time has elapsed relative to the reference signal.

[0168] Figure 10 The control device 402 shown has a control image forming apparatus 10 (see reference). Figure 14 The overall function of the control device 402 is as follows: The hardware structure of the control device 402 consists of a computer, which includes a CPU (Central Processing Unit, not shown), ROM (Read Only Memory) storing programs for implementing various processing programs, RAM (Random Access Memory) temporarily storing data, memory as storage components, and a network interface, etc.

[0169] [The switching timing of the short-circuit circuit and the switching timing of the voltage supplied to the application roller]

[0170] Figure 8 The left and right sides of the diagram illustrate the secondary transfer roller 34. The secondary transfer roller 34 on the left is in the state when it is inserted into the recess 178 as the transfer roller 36 rotates, while the secondary transfer roller 34 on the right is in the state when it is disengaged from the recess 178 as the transfer roller 36 rotates. Therefore, the secondary transfer roller 34 is actually a single roller.

[0171] In addition, such as Figure 8 As shown, the peripheral surface portion other than the recess 178 of the roller portion 174 of the transfer roller 36 is designated as the roller circumference portion 179.

[0172] Figure 13 For power supply device 410 (refer to) Figure 4 An explanatory diagram illustrating the switching times of the voltage supplied by (etc.). Figure 12 It is a timing diagram.

[0173] -The moment when the transfer voltage TV switches to the reverse voltage GV-

[0174] The secondary transfer position NT moves to the position as the transfer roller 36 rotates. Figure 4 The state of (A), Figure 8 , Figure 12 as well as Figure 13 The position of the S1 line is when the power supply device 410 (refer to) is in place. Figure 10 The voltage supplied to the secondary transfer roller 34 is from the transfer voltage TV (refer to...) Figure 12 Switching to reverse voltage GV (refer to) Figure 12 The specific time is after the reference signal has elapsed for a set period of time and the circuit switches to short-circuit circuit 500 (refer to...). Figure 10 Before that. And, as Figure 4 (A) Figure 8 as well as Figure 12 As shown, the S1 line is located at the position before the secondary transfer position NT enters the recess 178 and where the clip member 260 is provided. Furthermore, it is at the rear end PB of the sheet member P. Figure 13 (Same position)

[0175] -The moment of switching from applied circuit 400 to short-circuit circuit 500-

[0176] The secondary transfer position NT moves to the position as the transfer roller 36 rotates. Figure 4 The state of (B), Figure 8 , Figure 12 as well as Figure 13 The position of line S2 is the shaft component 34a of the grounding component 182 and the secondary transfer roller 34 (refer to...). Figure 4 (B)) contact is switched to short circuit 500 (refer to) Figure 10 as well as Figure 11 And the moment when it is short-circuited to the reference potential point G via the grounding component 182 and the resistor element 502. Specifically, the position of the S2 line is the part where the secondary transfer position NT is about to enter the recess 178 and the jacket component 260 is provided. Furthermore, the position of the S2 line is downstream in the conveying direction from the rear end PB of the sheet component P.

[0177] -The moments when switching from reverse voltage GV to intermediate voltage CV and from intermediate voltage CV to transfer voltage TV-

[0178] The secondary transfer position NT moves to the position as the transfer roller 36 rotates. Figure 5 The state of (A), Figure 8 , Figure 12 as well as Figure 13 The position of the S3 line is the moment when the voltage supplied by the power supply device 410 to the secondary transfer roller 34 is switched from the reverse voltage GV to the intermediate voltage CV. Specifically, it is after the reference signal has elapsed for a set time and before the secondary transfer position NT has disengaged from the recess 178. Furthermore, it is when the generated current is in a short-circuit state in the short-circuit circuit 500.

[0179] Then, the voltage supplied by the power supply device 410 is switched from the intermediate voltage CV to the transfer voltage TV. Furthermore, this switching occurs before the secondary transfer position NT disengages from the recess 178, and when the generated current is short-circuited through the short-circuit circuit 500. This occurs after a set time has elapsed from the reference signal.

[0180] -Moment of switching from short-circuit circuit 500 to applied circuit 400-

[0181] The secondary transfer position NT moves to the position as the transfer roller 36 rotates. Figure 5 The state of (B), Figure 8 , Figure 12 as well as Figure 13 The position of the S4 line is when the grounding member 182 moves away from the shaft member 34a and switches from the short-circuit circuit 500 to the application circuit 400. Specifically, it is the position where the secondary transfer position NT has just left the recess 178 and where the clip member 260 is provided.

[0182] Additionally, the position of the S4 line is relative to the inclined end 263B of the inclined surface 263A of the other end 263 of the jacket component 260 (see reference). Figure 8 (B) is consistent or roughly consistent. And, at this time, the rise of the transfer voltage TV is completed.

[0183] (The movement of the main structural components)

[0184] Next, the operation of the main structural components will be explained.

[0185] Sent out to Figure 14 The sheet component P of the paper feeding mechanism 48 shown is handed over to the chain gripper 66 and conveyed via the chain gripper 66. Specifically, the holding component 76 of the chain gripper 66 (see reference) Figure 6Hold the end of the sheet component P. Then, transfer the sheet component P via the chain gripper 66.

[0186] And, as Figure 3 (A) Figure 3 (B) and Figure 3 As shown in (C), the holding member 76, which holds the end of the sheet component P, is positioned within the recess 178 of the roller section 174 when it reaches the transfer cylinder 36. Furthermore, the sheet component P, conveyed by the chain clamp 66, is wound around the transfer cylinder 36 while being transported. At the secondary transfer position NT, the transported sheet component P is clamped between the roller section 174 of the transfer cylinder 36 and the transfer belt 31. Then, the toner image on the transfer belt 31 is transferred onto the sheet component P by the transfer electric field.

[0187] Specifically, such as Figure 4 As shown in (A), before the downstream end of the recess 178 where the holding member 76 is located reaches the secondary transfer position NT in the rotational direction, the contact roller 196 contacts the outer peripheral surface of the roller portion 174. Then, the grounding member 182 separates from the shaft member 34a, and a transfer electric field is formed at the secondary transfer position NT.

[0188] And, as Figure 4 (A) and Figure 4 As shown in (B), the contact roller 196, which is in contact with the outer peripheral surface of the roller portion 174, reaches the downstream end of the rotation direction of the recess 178 before the secondary transfer roller 34 reaches the downstream end of the recess 178.

[0189] Moreover, such as Figure 4 As shown in (B), when the contact roller 196 reaches the downstream end of the rotation direction of the recess 178, the main body 194 of the switching member 190 rotates, and the grounding member 182 contacts the shaft member 34a. As a result, the current generated by the voltage applied to the secondary transfer roller 34 by the application roller 44 flows to the grounding member 182 side, and the transfer electric field formed at the secondary transfer position NT is eliminated.

[0190] Moreover, such as Figure 4 (B) and Figure 5 As shown in (A), after the transfer roller 36 rotates and the holding member 76 passes the secondary transfer roller 34, the contact roller 196 reaches the upstream end of the recess 178 in the rotation direction. Since the grounding member 182 contacts the shaft member 34a during the period from when the contact roller 196 reaches the downstream end of the recess 178 in the rotation direction to when it reaches the upstream end, the transfer electric field formed at the secondary transfer position NT is eliminated.

[0191] Moreover, such as Figure 5 (A) and Figure 5As shown in (B), the contact roller 196, which reaches the upstream end of the rotation direction of the recess 178, contacts the outer peripheral surface of the transfer roller 36. Furthermore, after the contact roller 196 contacts the outer peripheral surface of the transfer roller 36, the wound portion of the outer peripheral surface of the transfer roller 36, on which the sheet member P is wound, is opposite to the secondary transfer roller 34 (= reaching the secondary transfer position NT).

[0192] like Figure 5 As shown in (B), when the contact roller 196 contacts the outer peripheral surface of the roller portion 174, the main body 194 of the switching member 190 rotates, and the grounding member 182 separates from the shaft member 34a. As a result, a transfer electric field is formed at the secondary transfer position NT.

[0193] In this way, by setting the outer peripheral surface of the transfer roller 36 and the recess 178 as cam surfaces, the switching component 190 switches the contact separation of the grounding component 182 relative to the shaft component 34a in conjunction with the rotation of the transfer roller 36.

[0194] Furthermore, at the secondary transfer position NT, the sheet component P is held between the roller portion 174 of the transfer roller 36 and the transfer belt 31. Then, the toner image on the transfer belt 31 is transferred onto the sheet component P at the secondary transfer position NT by the transfer electric field.

[0195] (effect)

[0196] Next, the function of the main structural components will be explained.

[0197] In the transfer apparatus 30, when the secondary transfer position NT disengages from the recess 178, the grounding member 182 separates from the shaft member 34a, and the short-circuit circuit 500 switches to the application circuit 400. As a result, the current generated by applying voltage to the secondary transfer roller 34 flows toward the transfer roller 36 side, forming a transfer electric field at the secondary transfer position NT.

[0198] For example, by using an electrical signal to begin applying voltage to the secondary transfer roller 34, a transfer electric field may sometimes be formed at the secondary transfer position NT. In such cases, time is taken from sending the electrical signal to completing the application of the transfer voltage TV to the secondary transfer roller 34. In other words, the time required to form the transfer electric field is relatively long.

[0199] However, in the transfer apparatus 30, as described above, the transfer electric field is formed by separating the grounding member 182 from the shaft member 34a. In other words, in the transfer apparatus 30, the transfer electric field is formed by mechanical action, not by an electrical signal. Therefore, compared to the case where the voltage of the secondary transfer roller 34 is applied starting by an electrical signal, the time required to form the transfer electric field in the transfer apparatus 30 is shorter.

[0200] Furthermore, in the transfer apparatus 30, when the NT plunges into the recess 178 at the secondary transfer position, the grounding member 182 contacts the shaft member 34a, switching from the application circuit 400 to the short-circuit circuit 500. As a result, the current generated by applying voltage to the secondary transfer roller 34 flows through the grounding member 182 and the resistive element 502 to the reference potential point G, thus short-circuiting. Consequently, the transfer electric field formed at the secondary transfer position NT is eliminated.

[0201] For example, by using an electrical signal to terminate the application of voltage to the secondary transfer roller 34, the transfer electric field formed at the secondary transfer position NT can sometimes be eliminated. In such cases, time is taken from sending the electrical signal to completely terminating the application of voltage to the secondary transfer roller 34. In other words, the time required to eliminate the transfer electric field is relatively long.

[0202] However, in the transfer apparatus 30, as described above, the transfer electric field is eliminated by bringing the grounding member 182 into contact with the shaft member 34a. In other words, in the transfer apparatus 30, the transfer electric field is eliminated by mechanical action, not by an electrical signal. Therefore, compared to the case where the voltage application to the secondary transfer roller 34 is terminated by an electrical signal, the time required to eliminate the transfer electric field is shorter in the transfer apparatus 30.

[0203] In this way, compared with the case where the application of the transfer voltage TV to the secondary transfer roller 34 is started and stopped according to the electrical signal, the time required to generate and eliminate the transfer electric field can be shortened in the transfer device 30.

[0204] Furthermore, before the short-circuit circuit 500 operates, the transfer voltage TV is switched to the reverse voltage GV according to the electrical signal. As a result, compared with the case where the transfer voltage TV is maintained when the short-circuit circuit 500 is operating, the inrush current to the short-circuit circuit 500 can be suppressed.

[0205] Furthermore, when the short-circuit circuit 500 is operating, the applied voltage is switched from the reverse voltage GV to the intermediate voltage CV, and then from the intermediate voltage CV to the transfer voltage TV, based on the electrical signal. Therefore, compared to the case where the voltage is switched directly from the reverse voltage GV to the transfer voltage TV, the time required to generate the transfer electric field can be shortened.

[0206] Furthermore, the resistance value of the resistor element 502 is set within the range of 1 MΩ or more and 4 MΩ or less. As a result, compared to the case where a short circuit occurs to the reference potential point G via a resistor element 502 with a resistance value of less than 1 MΩ, the surge current to the short-circuit circuit 500 can be suppressed.

[0207] Furthermore, the resistance value of the resistive element 502 is set to half the volume resistance value of the secondary transfer roller 34 when the transfer electric field is formed. As a result, compared to the case where a short circuit occurs at the reference potential point G via a resistive element whose resistance value is the same as that of the secondary transfer roller 34 when the transfer electric field is formed, the output current variation of the power supply device 410 can be suppressed.

[0208] This situation will be explained in detail here.

[0209] Figure 11 The resistive component 19A of the secondary transfer roller 34 extends from the contact point of the roller portion 34b of the secondary transfer roller 34 with the application roller 44 to the shaft member 34a. The resistive component 19B extends from the shaft member 34a of the roller portion 34b of the secondary transfer roller 34 to the transfer roller 36. The resistance values ​​of these resistive components 19A and 19B are the same. Furthermore, more precisely, the resistive component of the transfer belt 31 is included in the resistive component 19B, but it is not considered here.

[0210] Furthermore, the current flowing through the application circuit 400 is approximately "transfer voltage TV / (resistance value of resistor 19A + resistance value of resistor 19B)".

[0211] In the short-circuit circuit 500, since the grounding component 182 is in contact with the shaft component 34a, the current flowing through the short-circuit circuit 500 is approximately "transfer voltage TV / (resistance value of resistor 19A + resistance value of resistor 19B)". Therefore, by setting the resistance value of the resistor element 502 to be the same as the resistance value of resistor 19B, that is, half the resistance value of the volume resistance of the secondary transfer roller 34, the output change of the current output by the power supply device 410 when switching between the application circuit 400 and the short-circuit circuit 500 can be suppressed.

[0212] Furthermore, compared to the case where the short-circuit circuit 500 is short-circuited from the power supply device 410 to the reference potential point G, the surge current to the short-circuit circuit 500 can be suppressed.

[0213] Furthermore, the position of the S1 line of the secondary transfer position NT when switching from the application circuit 400 to the short-circuit circuit 500 is the location where the jacket member 260 is provided. Therefore, when the secondary transfer position NT deviates from the jacket member 260, a transfer electric field will not be formed at the secondary transfer position NT. Thus, compared to the case where the secondary transfer position NT is not at the jacket member 260 when switching to the short-circuit circuit 500, leakage current from the secondary transfer roller 34 to the metal roller body 252 can be prevented.

[0214] Furthermore, the secondary transfer position NT, which is the location of line S4 when switching from the short-circuit circuit 500 to the application circuit 400, is where the jacket member 260 is located. Therefore, a transfer electric field is not formed at the secondary transfer position NT until it reaches the jacket member 260. Consequently, compared to the case where the application circuit 400 is switched to when the secondary transfer position NT is not at the jacket member 260, leakage current from the secondary transfer roller 34 to the metal roller body 252 can be prevented.

[0215] Furthermore, in the transfer apparatus 30, the switching member 190 switches the grounding member 182 relative to the shaft member 34a in conjunction with the rotation of the transfer roller 36. Therefore, a transfer electric field is formed in conjunction with the rotation of the transfer roller 36, and the transfer electric field is eliminated.

[0216] Furthermore, in the transfer apparatus 30, by setting the outer peripheral surface of the transfer roller 36 and the recess 178 as cam surfaces, the switching member 190 switches the contact separation of the grounding member 182 relative to the shaft member 34a in conjunction with the rotation of the transfer roller 36. Therefore, compared to the case where a member with a cam surface is specially provided, the number of components is reduced.

[0217] Furthermore, in the transfer apparatus 30, the switching member 190 switches the contact separation of the grounding member 182 relative to the shaft member 34a by rotating around a rotating shaft portion 192, which is arranged in a U-shaped bend 194c when viewed from the width direction of the apparatus. Therefore, compared to a seesaw type case where the switching member extends to one side and the other side relative to the rotating shaft portion, the length of the switching member 190 in the longitudinal direction is shorter.

[0218] Furthermore, in the transfer device 30, the transfer roller 36 rotates, and the contact roller 196 reaches the outer circumferential surface of the transfer roller 36 after the holding member 76 passes the secondary transfer roller 34. That is, when the holding member 76 is facing the secondary transfer roller 34, the grounding member 182 contacts the shaft member 34a. In other words, when the holding member 76 is facing the secondary transfer roller 34, a transfer electric field is not formed at the secondary transfer position NT. In other words, when viewed from the depth direction of the device, when the intersection of the following line with the outer circumferential surface of the secondary transfer roller 34 is facing the holding member 76, a transfer electric field is not formed at the secondary transfer position NT. The line is the line connecting the rotation center of the secondary transfer roller 34 and the rotation center of the transfer roller 36.

[0219] Therefore, compared to the case where a transfer electric field is formed when the holding member 76 is facing the secondary transfer roller 34, the flow of current from the secondary transfer roller 34 to the holding member 76 can be suppressed. Compared to the case where the grounding member 182 is separated from the shaft member 34a when the holding member 76 is facing the secondary transfer roller 34, the flow of current from the secondary transfer roller 34 to the holding member 76 can be suppressed.

[0220] Furthermore, compared to the case where the grounding member 182 is separated from the shaft member 34a when the holding member 76 is facing the secondary transfer roller 34, the flow of current from the secondary transfer roller 34 to the holding member 76 can be suppressed in the transfer device 30, thereby suppressing the occurrence of defects in the transfer device 30.

[0221] Furthermore, in the transfer apparatus 30, the contact roller 196 disposed within the recess 178 contacts the outer peripheral surface of the transfer roller 36 before the wound portion of the sheet member P wound on the outer peripheral surface of the transfer roller 36 aligns with the secondary transfer roller 34. Thus, a transfer electric field is formed at the secondary transfer position NT before the wound portion of the sheet member P wound on the outer peripheral surface of the transfer roller 36 aligns with the secondary transfer roller 34.

[0222] Furthermore, in the transfer apparatus 30, when the secondary transfer roller 34 is facing the portion of the transfer roller 36 where the sheet member P is wound, the grounding member 182 is separated from the shaft member 34a. In other words, when the secondary transfer roller 34 is facing the portion of the transfer roller 36 where the sheet member P is wound, a transfer electric field is generated at the secondary transfer position NT. Therefore, compared to the case where the grounding member 182 is in contact with the shaft member 34a when the secondary transfer roller 34 is facing the leading edge portion of the sheet member P wound on the transfer roller 36, the area of ​​the toner image that can be transferred on the sheet member P is increased.

[0223] Furthermore, in the transfer apparatus 30, the contact roller 196 disposed within the recess 178 contacts the outer peripheral surface of the transfer cylinder 36 before the secondary transfer roller 34 reaches the portion of the wound sheet member P on the outer peripheral surface of the transfer cylinder 36. In other words, a transfer electric field is formed before the secondary transfer roller 34 reaches the portion of the wound sheet member P on the outer peripheral surface of the transfer cylinder 36. Therefore, a toner image can be transferred from the leading edge portion of the sheet member P wound on the transfer cylinder 36.

[0224] Furthermore, the image forming apparatus 10 includes a transfer device 30. Therefore, compared to a transfer device that terminates the application of voltage to the secondary transfer roller 34 via an electrical signal, it is possible to suppress poor image formation on the sheet member P due to unnecessary transfer electric fields. For example, it is possible to reduce the amount of blank space at the end of the sheet member P caused by unnecessary transfer electric fields.

[0225] Here, we will explain in detail how to reduce the amount of blank space at the end of the sheet component P caused by unnecessary transfer electric field.

[0226] In the transfer apparatus 30 of this embodiment, to prevent leakage between the secondary transfer roller 34 and the metal gripping member 76 and the metal roller body 252, the circuit switches from the short-circuit circuit 500 to the application circuit 400 at the secondary transfer position NT, which is the S4 line. On the other hand, the toner image will not be transferred to the end of the sheet member P until the transfer electric field is fully formed at the secondary transfer position NT. Therefore, the area from the secondary transfer position NT, where the S4 line is located, to the point where the transfer electric field is fully formed becomes a blank end area where transfer is impossible.

[0227] As described above, compared to the case where the voltage of the secondary transfer roller 34 is applied based on an electrical signal, the time required for the transfer apparatus 30 of this embodiment to form a transfer electric field is shortened. Therefore, compared to the case where the voltage of the secondary transfer roller 34 is applied based on an electrical signal, the transfer apparatus 30 of this embodiment can reduce the amount of blank space at the end of the sheet member P.

[0228] Furthermore, the image forming apparatus 10 has an application roller 44 that contacts the secondary transfer roller 34. When the grounding member 182 contacts the shaft member 34a while the shaft of the application roller 44 is powered, the current generated by the power supply flows to the shaft member 34a via the surface or interior of the secondary transfer roller 34. Here, the surface or interior of the secondary transfer roller 34 functions as a resistor. Therefore, compared to the case where a transfer electric field is formed by powering the shaft member 34a, it is possible to suppress the excessive current flowing in the path when grounding.

[0229] <Second Implementation>

[0230] according to Figure 16 An example of the transfer apparatus and image forming apparatus according to the second embodiment of this disclosure will be described. Furthermore, regarding the second embodiment, the differences from the first embodiment will be mainly described.

[0231] like Figure 16 As shown, the grounding unit 280 of the transfer apparatus according to the second embodiment has a grounding member 182 and a switching member 290 that switches the grounding member 182 from contact with the shaft member 34a.

[0232] The switching component 290 has a rotating shaft portion 192, a main body portion 294, and an excitation coil 298.

[0233] The main body 294 is made of iron and extends from the rotating shaft 192. Furthermore, the end portion of the main body 294 is located on the side opposite to the transfer cylinder 36, separated by the shaft member 34a. The main body 294 also supports the grounding member 182. Thus, the main body 294 rotates about the rotating shaft 192. The main body 294 is an example of a support portion.

[0234] The excitation coil 298 is disposed on the side opposite to the shaft member 34a, separated from the main body 294, and extends in the same direction as the main body 294.

[0235] In this structure, a low-voltage power supply (not shown) supplies or de-energizes the excitation coil 298, generating a magnetic field around the excitation coil 298, thereby causing the main body 294 to rotate to one side or the other. This causes the grounding component 182 to separate from the shaft component 34a.

[0236] Furthermore, regarding the second embodiment, in addition to the effect obtained by switching the contact separation of the grounding member 182 relative to the shaft member 34a in conjunction with the rotational operation of the transfer roller 36, other effects are obtained. Here, the voltage supplied to the excitation coil 298 is smaller than the voltage supplied to the application roller 44. As a result, in the excitation coil 298, power supply and de-energization can be switched electrically more quickly than when power supply and de-energization are switched electrically via the application roller 44.

[0237] <Other>

[0238] Furthermore, this disclosure is not limited to the embodiments described above.

[0239] In the above embodiment, the applied voltage is switched from the reverse voltage GV to the intermediate voltage CV, and then from the intermediate voltage CV to the transfer voltage TV, but it is not limited to this. It is also possible to switch directly from the reverse voltage GV to the transfer voltage TV.

[0240] Furthermore, for example, in the above embodiment, the voltage switches from the transfer voltage TV to the reverse voltage GV when the short-circuit circuit 500 is operating, but this is not a limitation. The transfer voltage TV can be maintained while the short-circuit circuit 500 is operating, or it can be set to the same potential as the reference potential point G. Alternatively, it can be set to a standby voltage whose absolute value is less than the absolute value of the transfer voltage TV when the short-circuit circuit 500 is operating. For example, the standby voltage can be the same voltage value as the intermediate voltage CV.

[0241] Furthermore, for example, in the above embodiment, the holding member 76, which is an example of a holding member, is shown as a structure that physically holds the end of the sheet member P. However, it is not limited to such a structure. For example, the end of the sheet member P can also be held by the force of attracting air.

[0242] Furthermore, for example, in the above embodiment, the wrapping member is a chain, but it is not limited to this. For example, the wrapping member can also be a belt.

[0243] For example, in the above embodiment, the toner image on the transfer belt 31 is transferred to the sheet component P, but for example, the toner image on the transfer roller can also be transferred to the sheet component P.

[0244] Furthermore, the image forming apparatus 10 has an application roller 44 that contacts the secondary transfer roller 34, but it is also possible to supply power to the shaft member 34a of the secondary transfer roller 34 without providing the application roller 44. However, when the application roller 44 is provided, it is possible to suppress the large current flowing through the short-circuit circuit 500 when grounded. This is because if the grounding member 182 contacts the shaft member 34a while the shaft of the application roller 44 is being powered, the current generated by the power supply flows through the shaft member 34a via the surface or interior of the secondary transfer roller 34, but the surface and interior of the secondary transfer roller 34 function as resistors.

[0245] Furthermore, in order to stabilize the non-contact preheating unit and the conveying posture of the conveyed sheet component P between the fixing device 100 and the secondary transfer position NT, an air supply unit that supplies air from below the sheet component P may also be provided.

[0246] Furthermore, the switching member 190 is not limited to a structure in which the transfer roller 36 is driven by a cam surface. For example, it may be driven by a cam or the like that rotates integrally with the transfer roller 36. Also, it is not limited to a mechanism that switches to a short-circuit circuit by swinging the switching member and contacting the shaft member 34a; for example, it may switch to a short-circuit circuit by swinging the switching member at a location different from the shaft member 34a, for example, by swinging the switching member and contacting the shaft member 44a of the application roller 44. Alternatively, it may be a movement other than swinging, for example, a structure in which the switching member moves linearly. In short, any working stop mechanism capable of switching the voltage applied to the transfer member to a short-circuit circuit that is short-circuited at the reference potential point instead of the transfer roller side is acceptable.

[0247] Furthermore, in the first embodiment described above, the outer peripheral surface of the roller portion 174 in the transfer roller 36 is set as a cam surface. However, a dedicated component with a cam surface may also be mounted on the shaft portion 176 of the transfer roller 36. However, in this case, the effect obtained by setting the outer peripheral surface of the roller portion 174 as a cam surface is not achieved.

[0248] And, as Figure 17As shown in the modified version, a cam surface 360 ​​with a different shape from other parts in the device depth direction can also be formed at the end of the roller portion 174 of the transfer roller 36 along the device depth direction. Moreover, the switching member 190 can be rotated through this cam surface 360. Thus, the grounding member 182 switches whether the secondary transfer roller 34 is grounded, regardless of the shape of the central part of the transfer roller 36 in the device depth direction.

[0249] Furthermore, in the above embodiment, the transfer roller 36 was used as the transfer roller, but for example, a component with a strip wound on the transfer roller 36 may also be used as the transfer roller.

[0250] Furthermore, in the first embodiment described above, the holding member 76 is mounted on a pair of chains 72, but it could also be mounted on the transfer roller 36, for example.

[0251] Furthermore, in the above embodiment, a holding member 76 is provided, but the holding member may not be provided.

[0252] Furthermore, in the above embodiment, the switching component 190 is rotated in conjunction with the rotation of the transfer cylinder 36 by means of a cam mechanism, but the switching component 190 can also be rotated in conjunction with the rotation of the transfer cylinder 36 by other mechanisms.

[0253] Furthermore, "linked with the rotational movement of the transfer roller 36" means that the cam mechanism or the like physically operates through the rotational movement of the transfer roller 36 itself to switch the contact separation of the grounding component 182 relative to the shaft component 34a. Therefore, it does not include, for example, a structure that reads the rotational movement through a separately provided sensor and switches the contact separation of the grounding component 182 using an electrical signal according to its operating condition.

[0254] Furthermore, the structure of the image forming apparatus is not limited to the structure described in the above embodiment, and various structures can be configured. Moreover, it can be implemented in various ways without departing from the spirit of this disclosure.

Claims

1. A transfer device comprising: The transfer component is powered by a voltage applied from a power supply device to form a transfer electric field that transfers the developer image onto the recording medium. A transfer cylinder is provided with a recess accommodating a holding member, which forms a transfer electric field between the transfer cylinder and the transfer member at a transfer position, wherein The holding component holds the end portion of the recording medium; A short-circuit circuit that short-circuits the voltage applied to the transfer component with a reference potential point; and The work stop mechanism activates the short-circuit circuit when the recess enters the transfer position as the transfer roller rotates, and deactivates the short-circuit circuit when the recess disengages from the transfer position as the transfer roller rotates. The power supply device is capable of switching the voltage applied to the transfer component between a transfer voltage and a standby voltage, wherein the transfer voltage is the voltage that forms the transfer electric field for transferring the developer image onto the recording medium, and the absolute value of the standby voltage is smaller than the absolute value of the transfer voltage. Before the short-circuit circuit operates, the voltage is switched from the transfer voltage to the standby voltage. Before the short-circuit circuit stops working, the voltage is switched from the standby voltage to the transfer voltage.

2. A transfer device, comprising: The transfer component is powered by a voltage applied from a power supply device to form a transfer electric field that transfers the developer image onto the recording medium. A transfer cylinder is provided with a recess accommodating a holding member, which forms a transfer electric field between the transfer cylinder and the transfer member at a transfer position, wherein The holding component holds the end portion of the recording medium; A short-circuit circuit that short-circuits the voltage applied to the transfer component with a reference potential point; and The work stop mechanism activates the short-circuit circuit when the recess enters the transfer position as the transfer roller rotates, and deactivates the short-circuit circuit when the recess disengages from the transfer position as the transfer roller rotates. The power supply device is capable of switching the voltage applied to the transfer component between a transfer voltage and a reverse voltage, wherein the transfer voltage is the voltage that forms a transfer electric field that transfers the developer image onto the recording medium, and the reverse voltage has the opposite polarity to the transfer voltage. Before the short-circuit circuit operates, the transfer voltage is switched to the reverse voltage. Before the short-circuit circuit stops working, the reverse voltage is switched to the transfer voltage.

3. The transfer apparatus according to claim 2, wherein, The power supply device is capable of switching the voltage applied to the transfer component between the transfer voltage, the reverse voltage, and an intermediate voltage between the transfer voltage and the reverse voltage. Before the short-circuit circuit stops working, the voltage is switched from the reverse voltage to the intermediate voltage, and then from the intermediate voltage to the transfer voltage.

4. The transfer apparatus according to any one of claims 1 to 3, wherein, The short-circuit circuit is short-circuited to the reference potential point via a resistive element whose resistance is half the resistance of the transfer component when the transfer electric field is formed.

5. The transfer apparatus according to any one of claims 1 to 3, wherein, The transfer component rotates around a shaft component made of metal. The power supply device has an application component that applies voltage by contacting the outer peripheral surface of the transfer component. The short-circuit circuit short-circuits the shaft component. The work stop mechanism has: A grounding component is provided in a manner that allows it to contact and separate relative to the shaft component, wherein the grounding component contacts the shaft component to short-circuit the shaft component; as well as A switching component, which switches the contact separation of the grounding component relative to the shaft component in conjunction with the rotation of the transfer roller.

6. The transfer apparatus according to any one of claims 1 to 3, wherein, The transfer roller has: A cylindrical roller body having the aforementioned recess; and The outer peripheral portion is located on the outer peripheral surface of the roller body. The work stop mechanism causes the short-circuit circuit to start working and short-circuit when the transfer position is located within the outer periphery.

7. The transfer apparatus according to claim 6, wherein, The work stop mechanism stops the short-circuit circuit from working when the transfer position is located within the outer periphery.

8. The transfer apparatus according to any one of claims 1 to 3, wherein, The short-circuit circuit short-circuits the voltage applied to the transfer component from the reference potential point via a resistive element with a resistance value of 1MΩ or more and 4MΩ or less.

9. The transfer device of claim 5, wherein, The transfer roller has a circular cross-section. By setting the outer circumferential surface of the transfer cylinder as a cam surface, the switching component, in conjunction with the rotational action of the transfer cylinder, switches the contact separation of the grounding component relative to the shaft component. The switching component has: A rotating shaft portion, wherein the rotating shaft portion is provided in a U-shaped bend when viewed from the axial direction of the shaft component, the rotating shaft portion extending along the axial direction; A contact portion, disposed on one side in a U-shape, rotates about the rotating shaft and contacts the outer peripheral surface of the transfer cylinder; and A support portion, which is located on the other side in a U-shape, rotates around the rotating shaft portion and supports the grounding component.

10. The transfer apparatus according to claim 9, wherein, The transfer apparatus has a conveying component for conveying a recording medium, and the conveying component has a holding component for holding the end of the recording medium. With the holding member facing the transfer member, the switching member brings the grounding member into contact with the shaft member.

11. The transfer apparatus according to claim 10, wherein, A recess is formed on the outer peripheral surface of the transfer cylinder, the recess extending along the axial direction, and the holding member is disposed in the recess. The transfer cylinder has a recording medium wound around its outer circumferential surface, which is held by the holding member disposed within the recess. With the contact portion in contact with the outer peripheral surface of the transfer cylinder, the switching member separates the grounding member from the shaft member; with the contact portion positioned in the recess of the transfer cylinder, the switching member brings the grounding member into contact with the shaft member. Before the portion of the recording medium wound on the outer peripheral surface of the transfer cylinder is opposite to the transfer component, the contact portion disposed in the recess contacts the outer peripheral surface of the transfer cylinder.

12. The transfer apparatus according to claim 5, wherein, The transfer device has a conveying component that has a holding component that holds the end of the recording medium and conveys the recording medium. With the transfer component facing the holding component, the switching component brings the grounding component into contact with the shaft component. A recess is formed on the outer peripheral surface of the transfer cylinder, the recess extending axially along the shaft member, and the holding member is disposed in the recess. The switching component, by setting a portion of the transfer roller as a cam surface, switches in conjunction with the rotation of the transfer roller whether the transfer component is grounded through the grounding component. The cam surface is formed at the end of the transfer cylinder in the axial direction, and the shape of the cam surface differs from that of the other parts in the axial direction. The recording medium being conveyed and wound on the transfer cylinder, With the transfer component facing the portion of the recording medium wound in the transfer cylinder, the switching component separates the grounding component from the shaft component. The switching component has: a rotating shaft portion that extends axially along the shaft portion; The switching member includes a contact portion that rotates around the rotating shaft and contacts the outer peripheral surface of the transfer cylinder. When the contact portion is in contact with the outer peripheral surface of the transfer cylinder, the switching member separates the grounding member from the shaft member. When the contact portion is positioned in the recess, the switching member contacts the grounding member with the shaft member. Before the transfer component reaches the portion of the recording medium wound on the outer peripheral surface of the transfer cylinder, the contact portion disposed in the recess contacts the outer peripheral surface of the transfer cylinder.

13. An image forming apparatus comprising: The image forming unit forms a developer image; and The transfer apparatus according to any one of claims 1 to 12 transfers the developer image formed by the image forming unit onto a recording medium.

Images