Transfer device, imaging forming device and power adjustment method

Abstract

To provide a transfer device capable of reducing noise and vibration generated when a transfer roller is switched, an image forming device and a power adjustment method.SOLUTION: An image forming device 10 includes: a switching mechanism receiving drive force supplied from a switching motor 481 to switch a transfer roller between a first roller and a second roller, the transfer roller forming a transfer nip part for sandwiching a sheet between an intermediate transfer belt and itself; a temporary setting processing unit 8d for temporarily setting a setting value of electric power to be supplied to the switching motor 481, to a predetermined specific value; a measurement processing part 8e, when the set value is temporarily set by the temporary setting processing unit 8d, measuring a switching time of the transfer roller using the switching mechanism; and an adjustment processing part 8f for adjusting the setting value based on a measurement result by the measurement processing part 8e.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electrophotographic image forming apparatus, a transfer device, and a power adjustment method. [Background technology]

[0002] An electrophotographic image forming apparatus includes an image carrier such as an intermediate transfer belt that carries a toner image, and a transfer roller such as a secondary transfer roller that forms a transfer nip portion that sandwiches a sheet between the image carrier (see, for example, Patent Document 1). Also, the image forming apparatus is known that includes a switching mechanism that receives a driving force supplied from a single motor and switches the transfer roller among a plurality of rollers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-163795 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in the image forming apparatus including the switching mechanism, if an excessive amount of power is supplied to the motor when switching the transfer roller, noise and vibration may be generated from around the switching mechanism.

[0005] An object of the present invention is to provide a transfer device, an image forming apparatus, and a power adjustment method that are capable of reducing noise and vibrations that occur when switching transfer rollers. [Means for solving the problem]

[0006] A transfer device according to one aspect of the present invention includes a switching mechanism, a provisional setting processing unit, a measurement processing unit, and an adjustment processing unit. The switching mechanism receives a driving force supplied from one motor and switches between a plurality of transfer rollers that form a transfer nip portion that sandwiches a sheet between an image carrier that carries a toner image and the transfer roller. The provisional setting processing unit provisionally sets a setting value of power supplied to the motor to a predetermined specific value. When the setting value is provisionally set by the provisional setting processing unit, the measurement processing unit measures a switching time of the transfer roller using the switching mechanism. The adjustment processing unit adjusts the setting value based on a measurement result by the measurement processing unit.

[0007] An image forming apparatus according to another aspect of the present invention includes the transfer device described above and forms an image on the sheet.

[0008] A power adjustment method according to another aspect of the present invention is executed in a transfer device having a switching mechanism that receives driving force supplied from one motor and switches between a plurality of transfer rollers that form a transfer nip portion that sandwiches a sheet between an image carrier that carries a toner image, and includes a provisional setting step, a measurement step, and an adjustment step. In the provisional setting step, a set value of power supplied to the motor is provisionally set to a predetermined specific value. In the measurement step, when the set value is provisionally set in the provisional setting step, a switching time of the transfer roller using the switching mechanism is measured. In the adjustment step, the set value is adjusted based on a measurement result in the measurement step. Effect of the Invention

[0009] According to the present invention, it is possible to reduce noise and vibrations that occur when switching the transfer roller. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of an image forming apparatus according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing the configuration of control-related devices in the image forming apparatus according to the embodiment. [Diagram 3] FIG. 3 is a schematic plan view of a main part of a transfer device in an image forming apparatus according to an embodiment. [Figure 4] FIG. 4 is a diagram showing a transfer device in a first operating state in the image forming apparatus according to the embodiment. [Diagram 5] FIG. 5 is a diagram showing a transfer device in the middle of switching from a first operating state to a second operating state in the image forming apparatus according to the embodiment. [Figure 6] FIG. 6 is a diagram showing a transfer device in a second operating state in the image forming apparatus according to the embodiment. [Figure 7] FIG. 7 is a diagram showing the transfer device in the middle of switching from the second operating state to the first operating state in the image forming apparatus according to the embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of a procedure for print control in the image forming apparatus according to the embodiment. [Figure 9] FIG. 9 is a flowchart showing an example of a procedure for power adjustment processing in the image forming apparatus according to the embodiment. [Figure 10] FIG. 10 is a diagram showing an example of table data used in the image forming apparatus according to the embodiment. [Figure 11] FIG. 11 is a diagram showing another example of table data used in the image forming apparatus according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0012] [Configuration of image forming apparatus 10] An image forming apparatus 10 according to an embodiment of the present invention is an apparatus that forms an image on a sheet by electrophotography. The sheet is a sheet-like image forming medium such as paper or a resin film.

[0013] The image forming apparatus 10 includes a paper feeder 30, a sheet transport device 3, a printing device 4, and one or more toner containers 400 arranged within a main body 1.

[0014] The sheet feeding device 30 stores a plurality of sheets and sends the sheets one by one to the sheet transport path 300. The sheet transport device 3 transports the sheets along the sheet transport path 300.

[0015] The printing device 4 executes a printing process for forming a toner image on the sheet supplied from the sheet supply device 30 through the sheet transport device 3 by electrophotography.

[0016] The printing device 4 includes a laser scanning unit 40 , one or more imaging devices 4 x , a transfer device 44 , and a fixing device 47 .

[0017] 1, the printing device 4 is a tandem color printing device. Therefore, the printing device 4 has four toner containers 400 corresponding to the four color toners 9 and four image forming devices 4x. Each of the image forming devices 4x has a drum-shaped photoconductor 41, a charging device 42, a developing device 43, and a primary cleaning device 45.

[0018] In each of the image forming devices 4x, the photoconductor 41 rotates, and the charging device 42 charges the surface of the photoconductor 41. Furthermore, in each of the image forming devices 4x, the developing device 43 develops the electrostatic latent image formed on the surface of the photoconductor 41 by the laser scanning unit 40 into a toner image.

[0019] Furthermore, the transfer device 44 includes an intermediate transfer belt 440, four primary transfer devices 441, a secondary transfer device 442, and a secondary cleaning device 443. The intermediate transfer belt 440 is rotatably supported by a pair of belt support rollers 440a.

[0020] An intermediate transfer belt 440 rotates while being in contact with the four photoconductors 41 , and four primary transfer devices 441 transfer the toner images from the four photoconductors 41 to the intermediate transfer belt 440 .

[0021] The secondary transfer device 442 transfers the toner image on the intermediate transfer belt 440 onto the sheet being transported through the sheet transport path 300. In this embodiment, the photoconductor 41 and the intermediate transfer belt 440 are an example of an image carrier.

[0022] As described above, in the printing device 4, the image creating device 4x, the laser scanning unit 40, and the primary transfer device 441 are an example of a toner image forming device that forms the toner image on the surface of the photoconductor 41 and the intermediate transfer belt 440. The secondary transfer device 442 transfers the toner image on the surface of the intermediate transfer belt 440 to the sheet.

[0023] A secondary cleaning device 443 removes waste toner from the intermediate transfer belt 440. In each of the image forming devices 4x, a primary cleaning device 45 removes waste toner remaining on the surface of the photoconductor 41.

[0024] The fixing device 47 fixes the toner image on the sheet by applying heat and pressure to the sheet. The sheet conveying device 3 discharges the sheet on which the image has been formed from the sheet conveying path 300.

[0025] Each toner container 400 supplies toner 9 to a corresponding developer unit 43 in the printing device 4 .

[0026] Furthermore, the image forming apparatus 10 includes a control device 8, an operation device 801, and a display device 802. The operation device 801 is a touch panel or operation buttons that accept operations by a person, etc. The display device 802 is a liquid crystal panel unit that displays information, etc.

[0027] As shown in FIG. 2, the control device 8 includes a central processing unit (CPU) 81, a random access memory (RAM) 82, a secondary storage device 83, and the like.

[0028] The CPU 81 is an example of a processor that controls electrical devices in the image forming apparatus 10 and processes various types of data by executing a computer program stored in the secondary storage device 83 or the like.

[0029] The CPU 81 includes a plurality of processing modules that are realized by executing the computer program, including a print control unit 8a, a switching control unit 8b, a parameter adjustment unit 8c, a temporary setting processing unit 8d, a measurement processing unit 8e, an adjustment processing unit 8f, a restoration processing unit 8g, and a determination processing unit 8h.

[0030] The print control unit 8a controls the print device 4 to execute the print process. The switching control unit 8b, the parameter adjustment unit 8c, the temporary setting processing unit 8d, the measurement processing unit 8e, the adjustment processing unit 8f, the restoration processing unit 8g, and the judgment processing unit 8h will be described later.

[0031] It is also possible that other processors such as a DSP (Digital Signal Processor) may execute various types of control and data processing instead of the CPU 81.

[0032] The RAM 82 is a storage device that temporarily stores the programs executed by the CPU 81 and data output and referenced in the process of the CPU 81 executing the programs.

[0033] The secondary storage device 83 is a computer-readable non-volatile data storage device. The secondary storage device 83 can store the programs and various data. For example, a hard disk drive and / or a combination of a solid state drive (SSD) is used as the secondary storage device 83.

[0034] 3, the secondary transfer device 442 includes a first roller 442a and a second roller 442b that are candidates for the transfer roller 4420, and a switching mechanism 46. In this embodiment, the first roller 442a and the second roller 442b are an example of a plurality of rollers. An apparatus including the secondary transfer device 442 and the CPU 81 is an example of the transfer device of the present invention.

[0035] The switching mechanism 46 rotatably supports the first roller 442a and the second roller 442b, and selectively brings one of the first roller 442a and the second roller 442b into contact with the intermediate transfer belt 440 as the transfer roller 4420. The switching mechanism 46 receives a driving force supplied from one switching motor 481 (see FIG. 2) and switches the transfer roller 4420, which forms the transfer nip portion N1 that sandwiches the sheet between the intermediate transfer belt 440, between the first roller 442a and the second roller 442b. The switching motor 481 is an example of a motor.

[0036] Specifically, the switching mechanism 46 performs a separation operation in which the first roller 442a (or the second roller 442b) (an example of the first roller of the present invention) in contact with the intermediate transfer belt 440 is separated from the intermediate transfer belt 440 by receiving a driving force supplied from a switching motor 481 rotating in one direction, and then performs a switching operation in which the roller facing the intermediate transfer belt 440 is switched from the first roller 442a (or the second roller 442b) to the second roller 442b (or the first roller 442a) (an example of the second roller of the present invention) by receiving a driving force supplied from the switching motor 481 rotating in the opposite direction to that during the separation operation, thereby bringing the second roller 442b (or the first roller 442a) into contact with the intermediate transfer belt 440.

[0037] 3 to 7, a sheet passing direction D1 is a direction in which the sheet passes through the transfer nip portion N1, and a width direction D2 is a direction intersecting the sheet passing direction D1. In this embodiment, the width direction D2 is a horizontal direction perpendicular to the sheet passing direction D1.

[0038] As shown in FIG. 4, the first roller 442a and the second roller 442b are positioned at a contact position P1 where they form a transfer nip N1 with the surface of the intermediate transfer belt 440 carrying the toner image, and thereby act as a transfer roller 4420 that transfers the toner image to the sheet passing through the transfer nip N1.

[0039] 3 shows a state in which the second roller 442b is disposed at the contact position P1. In this embodiment, the second roller 442b forms a transfer nip portion N1 that is longer in the width direction D2 than the first roller 442a.

[0040] In other words, the first roller 442a forms a transfer nip portion N1 that is shorter in the width direction D2 than the second roller 442b.

[0041] Hereinafter, the area on the surface of the intermediate transfer belt 440 that contacts the first roller 442a disposed at the contact position P1 is referred to as a first area A1, and the areas on both sides of the first area A1 in the width direction D2 are referred to as second areas A2.

[0042] The second area A2 is an example of a non-contact area that does not contact the first roller 442a disposed at the contact position P1 on the surface of the intermediate transfer belt 440. The first area A1 is an example of a contact area.

[0043] When the second roller 442b is disposed at the contact position P1, the second roller 442b contacts the surface of the intermediate transfer belt 440 across the first region A1 and the second region A2.

[0044] That is, when the first roller 442a is disposed at the contact position P1, the transfer nip N1 is formed in the first region A1. On the other hand, when the second roller 442b is disposed at the contact position P1, the transfer nip N1 is formed across the first region A1 and the second region A2 (see FIG. 3).

[0045] The image forming apparatus 10 further includes an image sensor 5 that reads an image in the second region A2 on the surface of the intermediate transfer belt 440. For example, the image sensor 5 may be a CIS (Contact Image Sensor). The image sensor 5 is an example of an image reading unit.

[0046] As described later, when the printing process is performed with the first roller 442a located at the contact position P1, the image forming apparatus 10 performs a parameter adjustment process in parallel with the printing process.

[0047] The parameter adjustment process is a process of forming a test image in the second area A2 on the surface of the intermediate transfer belt 440, having the image sensor 5 read the test image, and adjusting predetermined image-making parameters for the printing device 4 in accordance with the image read by the image sensor 5.

[0048] In the parameter adjustment process, the print control unit 8a causes the laser scanning unit 40 and the image forming device 4x to execute a process of forming a test image in the second area A2 on the surface of the intermediate transfer belt 440. In addition, the parameter adjustment unit 8c causes the image sensor 5 to read the test image and adjusts the image creation parameters.

[0049] Incidentally, when the transfer rollers 4420 are switched, it is desirable that the first roller 442a and the second roller 442b do not rub against the intermediate transfer belt 440. That is, it is desirable to move one roller in contact with the intermediate transfer belt 440 away from the intermediate transfer belt 440, and then move the other roller to a position facing the intermediate transfer belt 440, and then move the other roller closer to the intermediate transfer belt 440.

[0050] In the above case, typically, a separate drive source is required for moving the multiple rollers 442a, 442b in a direction toward and away from the intermediate transfer belt 440, and a separate drive source is required for selectively moving one of the multiple rollers 442a, 442b to a position facing the intermediate transfer belt 440.

[0051] On the other hand, it is desirable that the driving source required for switching the transfer roller 4420 be small.

[0052] In the image forming apparatus 10, the secondary transfer device 442 can operate the switching mechanism 46, which switches the transfer roller 4420, with one driving source while avoiding friction of the transfer roller 4420 against the intermediate transfer belt 440. The configuration will be described below.

[0053] [Configuration of switching mechanism 46] The switching mechanism 46 includes a pair of movable support parts 460 and a drive shaft 46x (see FIG. 3). The pair of movable support parts 460 rotatably support both ends of a rotation shaft 442x of the first roller 442a and both ends of a rotation shaft 442y of the second roller 442b.

[0054] As shown in FIGS. 4 to 7, each of the movable support parts 460 includes a first roller support member 461a, a second roller support member 461b, a first displacement member 463, a first spring 464a, a second spring 464b, and a second displacement member 465.

[0055] For example, the first roller support member 461a, the second roller support member 461b, the first displacement member 463 and the second displacement member 465 are each a molded member made of synthetic resin.

[0056] The first roller support member 461a rotatably supports the first roller 442a. Specifically, the first roller support member 461a rotatably supports an end of a rotation shaft 442x of the first roller 442a.

[0057] Similarly, the second roller support member 461b rotatably supports the second roller 442b. Specifically, the second roller support member 461b rotatably supports an end of a rotation shaft 442y of the second roller 442b.

[0058] The first roller support member 461a has a first protrusion 462a protruding along the width direction D2. Similarly, the second roller support member 461b has a second protrusion 462b protruding along the width direction D2.

[0059] The drive shaft 46x is disposed along the width direction D2 and is supported rotatably. The drive shaft 46x is an example of a shaft member. The drive shaft 46x is made of a metal such as iron.

[0060] The first displacement member 463 is supported by the drive shaft 46x so as to be able to swing. This allows the first displacement member 463 to swing about the drive shaft 46x. The secondary transfer device 442 further includes a first limiting portion 467a and a second limiting portion 467b that limit the swing range of the first displacement member 463.

[0061] The first limiting portion 467a comes into contact with the first displacement member 463 when the first displacement member 463 is in a predetermined first position, thereby limiting the swing range of the first displacement member 463 in the first rotation direction R1 to the first position. Fig. 4 shows a state in which the first displacement member 463 is in the first position.

[0062] The second limiting portion 467b comes into contact with the first displacement member 463 when the first displacement member 463 is in a predetermined second position, thereby limiting the swing range of the first displacement member 463 in the second rotation direction R2 to the second position. Fig. 6 shows a state in which the first displacement member 463 is in the second position.

[0063] As described above, the first displacement member 463 is supported by the drive shaft 46x so as to be displaceable between the first position and the second position around the drive shaft 46x. In other words, the first displacement member 463 is supported by the drive shaft 46x so as to be swingable between the first position and the second position around the drive shaft 46x.

[0064] Further, the first displacement member 463 supports the first roller support member 461a and the second roller support member 461b so that they can be brought into contact with and separated from the intermediate transfer belt 440. The first displacement member 463 supports the first roller support member 461a and the second roller support member 461b in a state where they are aligned in the displacement direction of the first displacement member 463.

[0065] Specifically, the first displacement member 463 has a first slide support portion 463a that supports the first roller support member 461a so that the first roller support member 461a can slide along a direction perpendicular to the drive shaft 46x. The first slide support portion 463a supports the first roller support member 461a so that the first roller support member 461a can be moved toward and away from the intermediate transfer belt 440.

[0066] Furthermore, the first displacement member 463 has a second slide support portion 463b that supports the second roller support member 461b so that the second roller support member 461b can slide along a direction perpendicular to the drive shaft 46x. The second slide support portion 463b supports the second roller support member 461b so that the second roller support member 461b can be moved toward and away from the intermediate transfer belt 440.

[0067] 4, the first position is a position of the first displacement member 463 when the first roller 442a supported by the first slide support portion 463a faces the contact position P1. As shown in FIG 6, the second position is a position of the first displacement member 463 when the second roller 442b supported by the second slide support portion 463b faces the contact position P1.

[0068] The first spring 464a is an example of a first elastic member that elastically urges the first roller support member 461a toward the intermediate transfer belt 440. The second spring 464b is an example of a second elastic member that elastically urges the second roller support member 461b toward the intermediate transfer belt 440.

[0069] The second displacement member 465 is integral with the drive shaft 46x and swings about the drive shaft 46x in conjunction with the rotation of the drive shaft 46x. That is, the second displacement member 465 is supported by the drive shaft 46x so as to be displaceable around the drive shaft 46x.

[0070] The second displacement member 465 has a sliding portion 465x. As the second displacement member 465 is displaced around the drive shaft 46x, the sliding portion 465x slides against the surfaces of the first convex portion 462a and the second convex portion 462b on the intermediate transfer belt 440 side.

[0071] The displacement direction of one of the first displacement member 463 and the second displacement member 465 is a first rotation direction R1, and the displacement direction of the other of the first displacement member 463 and the second displacement member 465 is a second rotation direction R2.

[0072] The first rotation direction R1 is an example of a first direction in which the sliding portion 465x is displaced from the first convex portion 462a to the second convex portion 462b. The second rotation direction R2 is an example of a second direction opposite to the first rotation direction R1. The second rotation direction R2 is a direction in which the sliding portion 465x is displaced from the second convex portion 462b to the first convex portion 462a.

[0073] The sliding portion 465x includes two locking portions 465a, 465b and a recess 465c. One of the two locking portions 465a, 465b is a first locking portion 465a, and the other is a second locking portion 465b.

[0074] The two locking portions 465a, 465b lock the first convex portion 462a and the second convex portion 462b, respectively, thereby holding the first roller support member 461a and the second roller support member 461b in a retracted position away from the intermediate transfer belt 440 against the biasing forces of the first spring 464a and the second spring 464b (see Figures 5 and 7).

[0075] The recess 465c is formed between the two locking portions 465a, 465b and one of the first protrusion 462a and the second protrusion 462b can enter the recess 465c (see FIGS. 4 and 6).

[0076] When the first protrusion 462a enters the recess 465c, the first roller support member 461a is released from the retracted position by the engagement of the first protrusion 462a (see FIG. 4). Similarly, when the second protrusion 462b enters the recess 465c, the second roller support member 461b is released from the retracted position by the engagement of the second protrusion 462b (see FIG. 6).

[0077] As shown in FIG. 4, the state of the secondary transfer device 442 when the first roller 442a is held at the contact position P1 by the first spring 464a is referred to as a first operating state.

[0078] On the other hand, as shown in FIG. 6, the state of the device when the second roller 442b is held at the contact position P1 by the second spring 464b is referred to as a second operating state.

[0079] 4 and 6, the second displacement member 465 is in the same position when the device state is the first operating state and when the device state is the second operating state. Hereinafter, the position of the second displacement member 465 when the device state is the first operating state or the second operating state will be referred to as a reference position.

[0080] As shown in FIG. 4, when the first displacement member 463 is in the first position, the first convex portion 462a enters the concave portion 465c, and the second convex portion 462b is engaged with the first engaging portion 465a, the device state is the first operating state.

[0081] As shown in FIG. 6, when the first displacement member 463 is in the second position, the second convex portion 462b enters the concave portion 465c, and the first convex portion 462a is engaged with the second engaging portion 465b, the device state is the second operating state.

[0082] The secondary transfer device 442 further includes a switching drive device 48 that displaces the second displacement member 465 in the first rotation direction R1 and the second rotation direction R2 (see FIG. 2). The switching drive device 48 includes a switching motor 481 and a motor drive circuit 482 (see FIG. 2). Furthermore, the switching drive device 48 further includes a gear mechanism 480 (see FIG. 3).

[0083] The motor drive circuit 482 rotates the switching motor 481 in a predetermined forward rotation direction or a reverse rotation direction opposite thereto, in accordance with a control command from the switching control unit 8b of the control device 8. The gear mechanism 480 transmits the rotational force of the switching motor 481 to the drive shaft 46x.

[0084] When the switching motor 481 rotates in the forward rotation direction, the second displacement member 465 is displaced in the first rotation direction R1. When the switching motor 481 rotates in the reverse rotation direction, the second displacement member 465 is displaced in the second rotation direction R2. That is, the switching drive device 48 displaces the second displacement member 465 in the first rotation direction R1 and the second rotation direction R2 by driving the drive shaft 46x to rotate in each of the two rotation directions.

[0085] The motor driving circuit 482 supplies the switching motor 481 with the power set by the control device 8. For example, in the image forming apparatus 10, a switching element (not shown) capable of switching the conduction and interruption of the power supply path between a power source (not shown) that supplies power to the switching motor 481 and the switching motor 481 is provided on the power supply path between the switching motor 481 and a power source (not shown). The motor driving circuit 482 inputs a PWM signal having a duty ratio set in advance by the control device 8 to the switching element to control the on / off of the switching element. This adjusts the amount of power supplied to the switching motor 481. The duty ratio is an example of a set value of the power supplied to the switching motor 481. The control device 8 may adjust the amount of power supplied to the switching motor 481 by adjusting the output voltage of the power source (another example of a set value of the power supplied to the switching motor 481).

[0086] [Second roller switching process] Hereinafter, a second roller switching process for switching the device state from the first operating state to the second operating state will be described.

[0087] The switching drive device 48 causes the switching mechanism 46 to perform the separating operation when the device state is the first operating state. Specifically, when the device state is the first operating state, the switching drive device 48 displaces the second displacement member 465 in the first rotation direction R1. As a result, the second locking portion 465b is displaced to a position where it locks the first convex portion 462a and the second convex portion 462b, while the first displacement member 463 is held at the first position (see FIG. 5).

[0088] Hereinafter, the position of the second displacement member 465 when the second engagement portion 465b is displaced to a position where it engages the first convex portion 462a and the second convex portion 462b due to the displacement of the second displacement member 465 in the first rotation direction R1 is referred to as the first folded position.

[0089] Furthermore, after the switching mechanism 46 performs the separating operation, the switching drive device 48 causes the switching mechanism 46 to perform the switching operation. Specifically, after the second displacement member 465 reaches the first turning position, the switching drive device 48 displaces the second displacement member 465 in the second rotation direction R2, and stops the second displacement member 465 at the reference position.

[0090] As a result, with the first convex portion 462a and the second convex portion 462b being integrated with the sliding portion 465x by the biasing force of the first spring 464a and the second spring 464b, the first displacement member 463 is displaced from the first position to the second position in conjunction with the second displacement member 465, and further the recess 465c is displaced to a position that allows the second convex portion 462b to enter and stops, and the device state becomes the second operating state (see Figure 6).

[0091] The first protruding portion 462a and the second protruding portion 462b are pressed against the sliding portion 465x by the biasing forces of the first spring 464a and the second spring 464b, and are integrated with the sliding portion 465x by the static friction force between them.

[0092] [First roller switching process] Hereinafter, a first roller switching process for switching the device state from the second operating state to the first operating state will be described.

[0093] The switching drive device 48 causes the switching mechanism 46 to perform the separating operation when the device state is the second operating state. Specifically, when the device state is the second operating state, the switching drive device 48 displaces the second displacement member 465 in the second rotation direction R2. As a result, the first engagement portion 465a is displaced to a position where it engages the first convex portion 462a and the second convex portion 462b while the first displacement member 463 is held at the second position (see FIG. 7).

[0094] Hereinafter, the position of the second displacement member 465 when the first engagement portion 465a is displaced in the second rotation direction R2 to a position where it engages the first convex portion 462a and the second convex portion 462b is referred to as the second folded position.

[0095] Furthermore, the switching drive device 48 causes the switching mechanism 46 to perform the switching operation after the switching mechanism 46 performs the separating operation. Specifically, the switching drive device 48 displaces the second displacement member 465 in the first rotation direction R1 after the second displacement member 465 reaches the second turning position, and stops the second displacement member 465 at the reference position. As a result, the first displacement member 463 displaces from the second position to the first position in conjunction with the second displacement member 465 in a state in which the first convex portion 462a and the second convex portion 462b are integrated with the sliding portion 465x by the biasing force of the first spring 464a and the second spring 464b, and further, the recessed portion 465c displaces to a position where the first convex portion 462a enters and stops, and the device state becomes the first operating state (see FIG. 4).

[0096] As described above, the switching drive device 48 switches the device state from one of the first operating state and the second operating state to the other by displacing the second displacement member 465 in the first rotational direction R1 and the second rotational direction R2 in accordance with the control command of the switching control unit 8b.

[0097] By employing the switching mechanism 46 and the switching drive device 48, it is possible to operate the mechanism for switching the transfer roller 4420 with a single switching motor 481 while preventing the transfer roller 4420 from rubbing against the intermediate transfer belt 440.

[0098] In this embodiment, the first displacement member 463 of one movable support part 460 has a convex first detected part 463c, and the second displacement member 465 of the one movable support part 460 has a convex second detected part 465d.

[0099] Furthermore, the secondary transfer device 442 includes a first detection sensor 468a, a second detection sensor 468b, a third detection sensor 468c, a fourth detection sensor 468d, and a fifth detection sensor 468e. The first detection sensor 468a and the second detection sensor 468b detect the first detection target portion 463c at two predetermined points on the movement path of the first detection target portion 463c when the first displacement member 463 is displaced.

[0100] The third detection sensor 468c, the fourth detection sensor 468d, and the fifth detection sensor 468e detect the second detected portion 465d at three predetermined points on the movement path of the second detected portion 465d when the second displacement member 465 is displaced.

[0101] The first detection sensor 468a, the second detection sensor 468b, the third detection sensor 468c, the fourth detection sensor 468d, and the fifth detection sensor 468e may each be a non-contact object detection sensor such as a transmissive photosensor or a reflective photosensor, or a contact object detection sensor such as a limit switch.

[0102] In this embodiment, when the first displacement member 463 is in the first position, the first detected portion 463c is detected by the first detection sensor 468a (see FIGS. 4 and 5). When the first displacement member 463 is in the second position, the first detected portion 463c is detected by the second detection sensor 468b (see FIGS. 6 and 7).

[0103] That is, the first detection sensor 468a detects that the first displacement member 463 is in the first position, and the second detection sensor 468b detects that the first displacement member 463 is in the second position.

[0104] When the recess 465c of the second displacement member 465 is in a position facing the contact position P1, the second detected portion 465d is detected by the third detection sensor 468c (see FIGS. 4 and 6). When the second displacement member 465 is in the first folded position, the second detected portion 465d is detected by the fourth detection sensor 468d (see FIG. 5). When the second displacement member 465 is in the second folded position, the second detected portion 465d is detected by the fifth detection sensor 468e (see FIG. 7).

[0105] The position of the second displacement member 465 when the recess 465c of the second displacement member 465 is in a position facing the contact position P1 is the reference position. That is, the third detection sensor 468c detects that the second displacement member 465 is in the reference position. Furthermore, the fourth detection sensor 468d detects that the second displacement member 465 is in the first folded position. Furthermore, the fifth detection sensor 468e detects that the second displacement member 465 is in the second folded position.

[0106] The switching control unit 8b determines the positions of the first displacement member 463 and the second displacement member 465 based on the state in which the first detection sensor 468a, the second detection sensor 468b, the third detection sensor 468c, the fourth detection sensor 468d, and the fifth detection sensor 468e detect the first detected portion 463c or the second detected portion 465d.

[0107] Furthermore, the switching control unit 8b controls the displacement direction of the second displacement member 465 and the timing at which the second displacement member 465 is stopped, based on the determination results of the positions of the first displacement member 463 and the second displacement member 465.

[0108] In this embodiment, the initial state of the secondary transfer device 442 is the first operating state (see FIG. 4). When the secondary transfer device 442 is in the first operating state, the printing device 4 is capable of the printing process on the sheet having a specific size or smaller that corresponds to the first area A1 on the surface of the intermediate transfer belt 440. That is, the specific size is the size of the sheet onto which the toner image can be transferred by the first roller 442a.

[0109] On the other hand, when the printing process is performed on the sheet exceeding the specific size, it is necessary for the state of the secondary transfer device 442 to be switched from the first operating state to the second operating state.

[0110] [Print Control] Next, an example of a print control procedure executed by the print control unit 8a, the switching control unit 8b, and the parameter adjustment unit 8c will be described with reference to the flowchart shown in FIG.

[0111] The print control unit 8a starts the print control when a print job occurs. For example, the print job is received from an information processing device that can communicate with the print job by a communication device (not shown). In the following description, S1, S2, ... represent identification codes of multiple steps in the print control.

[0112] <Process S1> When the print job is generated, the print control unit 8a judges whether the size of the sheet to be printed exceeds the specific size or not. Information on the size of the sheet is included in the print job.

[0113] If the print control unit 8a determines that the size of the sheet to be printed exceeds the specific size, it shifts the process to step S2, and if not, it shifts the process to step S6.

[0114] <Process S2> In step S2, the switching control unit 8b causes the switching drive device 48 to execute the second roller switching process for switching the state of the secondary transfer device 442 from the first operating state to the second operating state, and transitions the process to step S3. The content of the second roller switching process is as described above.

[0115] <Process S3> In step S3, the print control unit 8a causes the image forming device 4x and the laser scanning unit 40 to execute a process of developing a print image according to the print job. Furthermore, the print control unit 8a executes a process of step S4 in parallel with the process of step S3.

[0116] By the process of step S3, the print image can be formed as the toner image on the surface of intermediate transfer belt 440 in an area spanning first area A1 and second area A2.

[0117] <Process S4> In step S4, the print control unit 8a causes the secondary transfer device 442 and the fixing device 47 to transfer the print image onto the sheet and further fix the image onto the sheet, and then the process proceeds to step S5.

[0118] In step S4, the second roller 442b having a larger width transfers the toner image in the range spanning the first area A1 and the second area A2 on the surface of the intermediate transfer belt 440 onto the sheet having a size larger than the specific size.

[0119] <Process S5> In step S5, the switching control unit 8b causes the switching drive device 48 to execute the first roller switching process for switching the state of the secondary transfer device 442 from the second operating state to the first operating state. As a result, the secondary transfer device 442 transitions to the initial state, and the print control ends.

[0120] <Process S6> Meanwhile, in step S6, the print control unit 8a causes the image forming device 4x and the laser scanning unit 40 to execute a process of developing the print image according to the print job and a predetermined test image. Furthermore, the print control unit 8a executes a process of step S7 in parallel with the process of step S6.

[0121] In step S6, the print control unit 8a causes the image forming device 4x and the laser scanning unit 40 to execute a process of forming the print image in the first area A1 on the surface of the intermediate transfer belt 440 and developing the test image in the second area A2.

[0122] For example, the test image includes a number of rectangular patch images each having a different combination of color and density.

[0123] <Process S7> In step S7, the print control unit 8a causes the secondary transfer device 442 and the fixing device 47 to execute a process of transferring the print image onto the sheet and further fixing the image onto the sheet, and then the process proceeds to step S8.

[0124] In step S7, a first roller 442a having a small width transfers the toner image in a first area A1 on the surface of the intermediate transfer belt 440 onto the sheet having a size equal to or smaller than the specific size.

[0125] Therefore, the test image formed in the second region A2 on the surface of the intermediate transfer belt 440 is not transferred to the sheet and remains on the surface of the intermediate transfer belt 440. However, the toner 9 constituting the test image is eventually removed from the surface of the intermediate transfer belt 440 by the secondary cleaning device 443.

[0126] <Process S8> In step S8, the parameter adjustment unit 8c causes the image sensor 5 to execute a process of reading the test image, and acquires data of the image read by the image sensor 5. Furthermore, the parameter adjustment unit 8c transitions the process to step S9.

[0127] <Process S9> In step S9, the parameter adjustment unit 8c adjusts the image creation parameters related to the printing device 4 in accordance with the data of the read image obtained from the image sensor 5. This completes the print control.

[0128] For example, the parameter adjustment unit 8c adjusts a development density parameter such as a correction value for the development bias voltage of the developing device 43 or a density correction value for the print image, depending on the difference between the density of the test image in the read image and a predetermined target density. The development density parameter is an example of the image creation parameter.

[0129] Further, the parameter adjustment unit 8c adjusts the timing at which the laser scanning unit 40 writes the electrostatic latent image onto the photoconductor 41 of each of the image forming devices 4x, depending on the difference between the color of the test image in the read image and a predetermined target color. The timing at which the electrostatic latent image is written is also an example of the image forming parameter.

[0130] As described above, when the secondary transfer device 442 is in the first operating state and the printing process is performed on the sheet of a size not exceeding the specific size, the print control unit 8a causes the printing device 4 to perform a process of forming the print image in the first area A1 on the surface of the intermediate transfer belt 440 and forming the test image in the second area A2 (steps S6 and S7 in Figure 8).

[0131] Then, the parameter adjustment unit 8c adjusts the predetermined image-creation parameters related to the printing device 4 according to the state of the test image included in the image read by the image sensor 5 (step S9 in FIG. 8).

[0132] Therefore, the image forming apparatus 10 can adjust the image-creation parameters frequently while executing the print process, without requiring a dedicated period for adjusting the image-creation parameters.

[0133] In addition, when the initial state of the secondary transfer device 442 is the first operating state, the switching control unit 8b causes the switching drive device 48 to execute a process of switching the state of the secondary transfer device 442 from the first operating state to the second operating state before the printing process is started on the sheet of a size larger than the specific size (step S2 in Figure 8).

[0134] Furthermore, after the printing process on the sheet having a size larger than the specific size is completed, the switching control unit 8b causes the switching drive device 48 to execute a process of switching the state of the secondary transfer device 442 from the second operating state to the first operating state (step S5 in Figure 8).

[0135] The processing by the switching control unit 8b enables the parameter adjustment unit 8c to adjust the image creation parameters with high frequency.

[0136] However, if an excessive amount of power is supplied to the switching motor 481 when switching the transfer roller 4420, noise and vibration may occur around the switching mechanism 46.

[0137] In the image forming apparatus 10, the secondary transfer device 442 can reduce noise and vibrations that occur when switching the transfer roller 4420. The configuration thereof will be described below.

[0138] The provisional setting processing unit 8d provisionally sets the duty ratio of the PWM signal output from the motor drive circuit 482 to a predetermined specific value. For example, the specific value is 100 percent. The specific value may be set arbitrarily within a range in which the switching motor 481 does not become locked due to insufficient torque.

[0139] The provisional setting processing unit 8d provisionally sets the duty ratio of the PWM signal each time a predetermined adjustment condition is satisfied. For example, the adjustment condition is that the cumulative number of printed sheets of the image forming apparatus 10 reaches a multiple of a predetermined number of sheets. The adjustment condition may be that the cumulative number of executions of the print job reaches a multiple of a predetermined number. The adjustment condition may be that a predetermined time has elapsed since the previous duty ratio of the PWM signal was set. The adjustment condition may be that a predetermined user operation has been received.

[0140] The measurement processing unit 8e measures the switching time of the transfer roller 4420 using the switching mechanism 46 when the duty ratio of the PWM signal is temporarily set by the temporary setting processing unit 8d.

[0141] For example, when the second roller switching process is executed, the measurement processing unit 8e measures the elapsed time from when the third detection sensor 468c detects the start of movement of the second displacement member 465 from the reference position to the first turning position to when the third detection sensor 468c detects the end of movement of the second displacement member 465 from the first turning position to the reference position.

[0142] The adjustment processing unit 8f adjusts the duty ratio of the PWM signal based on the measurement result by the measurement processing unit 8e.

[0143] For example, in image forming apparatus 10, table data TD10 (see FIG. 10) in which the switching time of transfer roller 4420 and the duty ratio of the PWM signal correspond to each other is stored in advance in secondary storage device 83. In table data TD10, the correspondence between the two is defined such that the longer the switching time of transfer roller 4420, the larger the duty ratio of the PWM signal. Here, the switching time of transfer roller 4420 becomes longer as the load torque applied to switching motor 481 increases. Therefore, it can be said that the correspondence between the switching time of transfer roller 4420 and the duty ratio of the PWM signal is defined such that the larger the load torque applied to switching motor 481, the larger the duty ratio of the PWM signal.

[0144] The adjustment processing unit 8f adjusts the duty ratio of the PWM signal by using the table data TD10. That is, the adjustment processing unit 8f adjusts the duty ratio of the PWM signal to a value associated with the measurement result by the measurement processing unit 8e in the table data TD10.

[0145] The adjustment processing unit 8f may adjust the duty ratio of the PWM signal by using a formula capable of calculating the duty ratio of the PWM signal corresponding to the switching time of the transfer roller 4420.

[0146] The adjustment processing unit 8f adjusts the duty ratio of the PWM signal every time the adjustment condition is satisfied.

[0147] When switching of the transfer roller 4420 using the switching mechanism 46 fails after the adjustment of the duty ratio of the PWM signal by the adjustment processing unit 8f, the restoration processing unit 8g restores the duty ratio of the PWM signal to the value before the immediately preceding provisional setting.

[0148] The determination processing unit 8h determines that a failure has occurred when switching of the transfer roller 4420 using the switching mechanism 46 fails after the restoration processing unit 8g restores the duty ratio of the PWM signal.

[0149] [Power adjustment processing] Next, referring to the flowchart shown in FIG. 9, an example of the procedure of the power adjustment processing executed by the switching control unit 8b, the temporary setting processing unit 8d, the measurement processing unit 8e, the adjustment processing unit 8f, the restoration processing unit 8g, and the judgment processing unit 8h will be described.

[0150] <Process S11> First, in step S11, the provisional setting processing unit 8d determines whether or not the adjustment condition is satisfied.

[0151] If the provisional setting processing unit 8d determines that the adjustment condition is satisfied, it shifts the process to step S12, and if not, it waits until the adjustment condition is satisfied.

[0152] <Process S12> In step S12, the provisional setting processing unit 8d provisionally sets the duty ratio of the PWM signal output from the motor drive circuit 482 to the specific value, and shifts the process to step S13. Step S12 is an example of a provisional setting step.

[0153] <Process S13> In step S13, the switching control unit 8b causes the switching drive device 48 to execute the second roller switching process for switching the state of the secondary transfer device 442 from the first operating state to the second operating state. Furthermore, the measurement processing unit 8e executes the process of step S14 in parallel with the process of step S13.

[0154] <Process S14> In step S14, the measurement processing unit 8e measures the switching time of the transfer roller 4420 in the second roller switching process, and shifts the process to step S15. Step S14 is an example of a measurement process.

[0155] <Process S15> In step S15, the adjustment processing unit 8f adjusts the duty ratio of the PWM signal based on the measurement result in step S14, and transitions the process to step S16. Step S15 is an example of an adjustment process. The transition of the process to step S16 may be reserved until the print job for printing on the sheet of a size equal to or smaller than the specific size occurs.

[0156] <Process S16> In step S16, the switching control unit 8b causes the switching drive device 48 to execute the first roller switching process for switching the state of the secondary transfer device 442 from the second operating state to the first operating state. Furthermore, the restoration processing unit 8g executes the process of step S17 in parallel with the process of step S16.

[0157] <Process S17> In step S17, the restoration processing unit 8g determines whether the first roller switching process is successful. Specifically, when the first roller switching process is not completed even after a predetermined allowable time has elapsed, the restoration processing unit 8g determines that the first roller switching process has failed.

[0158] If the restoration processing unit 8g determines that the first roller switching process has been successful, it shifts the process to step S11, and if not, it shifts the process to step S18.

[0159] <Process S18> In step S18, the restoration processing unit 8g restores the duty ratio of the PWM signal to the value before the immediately preceding provisional setting, and the process proceeds to step S19. Step S18 is an example of a restoration process. The transition of the process to step S19 may be reserved until the print job for printing on the sheet of a size equal to or smaller than the specific size occurs.

[0160] <Process S19> In step S19, the switching control unit 8b causes the switching drive device 48 to execute the first roller switching process. That is, the switching control unit 8b causes the switching drive device 48 to retry the first roller switching process. Furthermore, the determination processing unit 8h executes the process of step S20 in parallel with the process of step S19.

[0161] <Process S20> In step S20, the determination processing unit 8h determines whether or not the first roller switching process has failed.

[0162] If the determination processing unit 8h determines that the first roller switching process has failed, it shifts the process to step S21, and if not, it shifts the process to step S11.

[0163] <Process S21> In step S21, the determination processing unit 8h determines that a malfunction has occurred. In this case, the control device 8 causes the display device 802 to display a message indicating that the transfer roller 4420 cannot be switched due to a malfunction. In addition, the control device 8 restricts the execution of the print job.

[0164] As described above, in the image forming apparatus 10, after the duty ratio of the PWM signal is temporarily set, the switching time of the transfer roller 4420 is measured, and the duty ratio of the PWM signal is adjusted based on the measurement result. This makes it possible to adjust the power supplied to the switching motor 481 to an appropriate amount according to the load torque applied to the switching motor 481. Therefore, it is possible to reduce the noise and vibration generated when the transfer roller 4420 is switched.

[0165] Furthermore, in the image forming apparatus 10, the duty ratio of the PWM signal is adjusted every time the adjustment condition is satisfied. This makes it possible to adjust the power supplied to the switching motor 481 in accordance with the change in the load torque applied to the switching motor 481 caused by aging deterioration of the switching mechanism 46 or the like.

[0166] Furthermore, in the image forming apparatus 10, if switching of the transfer roller 4420 fails after adjusting the duty ratio of the PWM signal, the duty ratio of the PWM signal is restored to the value before the immediately preceding provisional setting. This makes it possible to avoid erroneous failure determination even when the torque of the switching motor 481 is insufficient due to the adjustment, compared to a configuration in which a failure is determined to have occurred when switching of the transfer roller 4420 fails after adjusting the duty ratio of the PWM signal.

[0167] During the separating operation of the switching mechanism 46, the roller is separated from the intermediate transfer belt 440 against the biasing force of the first spring 464a or the second spring 464b, so a larger load torque is applied to the switching motor 481 than during the switching operation of the switching mechanism 46. Therefore, in a configuration in which the duty ratio of the PWM signal output from the motor drive circuit 482 during the separating operation and the duty ratio of the PWM signal output from the motor drive circuit 482 during the switching operation are set uniformly based on the measurement result by the measurement processing unit 8e, it is considered that the torque of the switching motor 481 will be insufficient during the separating operation.

[0168] In response to this, a configuration can be considered in which the adjustment processing unit 8f individually adjusts the duty ratio of the PWM signal output from the motor driving circuit 482 during the separation operation and the duty ratio of the PWM signal output from the motor driving circuit 482 during the switching operation based on the measurement results by the measurement processing unit 8e.

[0169] For example, the adjustment processing unit 8f can individually adjust the duty ratio of the PWM signal output from the motor drive circuit 482 during the separating operation and the duty ratio of the PWM signal output from the motor drive circuit 482 during the switching operation, using table data TD11 shown in FIG. 11. The table data TD11 is data in which the switching time of the transfer roller 4420, the duty ratio of the PWM signal output from the motor drive circuit 482 during the separating operation, and the duty ratio of the PWM signal output from the motor drive circuit 482 during the switching operation are associated with each other. In the table data TD11, the correspondence between the two is defined so that the longer the switching time of the transfer roller 4420, the larger the duty ratio of the PWM signal output from the motor drive circuit 482 during the switching operation becomes. In addition, in the table data TD11, the correspondence between the two is defined so that the duty ratio of the PWM signal output from the motor drive circuit 482 during the separating operation is constant, regardless of the length of the switching time of the transfer roller 4420. This makes it possible to prevent the torque of the switching motor 481 from becoming insufficient during the separating operation, and to reduce noise and vibrations that occur when switching the transfer roller 4420. Note that in the table data TD11, a correspondence relationship between the two may be defined such that the longer the switching time of the transfer roller 4420, the larger the duty ratio of the PWM signal output from the motor drive circuit 482 during the separating operation.

[0170] The adjustment processing unit 8f may adjust the output voltage of the power supply during the separating operation and the output voltage of the power supply during the switching operation separately based on the measurement result by the measurement processing unit 8e.

[0171] [First application example] In the secondary transfer device 442, the first displacement member 463 and the second displacement member 465 are supported so as to be swingable about the drive shaft 46x. However, the first displacement member 463 may be supported so as to be slidably displaceable between the first position and the second position by a predetermined slide support mechanism. In this case, the second displacement member 465 is also supported so as to be slidably displaceable in parallel to the displacement direction of the first displacement member 463.

[0172] Furthermore, when the second displacement member 465 is supported so as to be slidably displaceable, the gear mechanism 480 of the switching drive device 48 may be a rack-and-pinion mechanism.

[0173] [Second application example] Furthermore, when the image forming apparatus 10 is a monochrome image forming apparatus, it is considered that the structure of the secondary transfer device 442 is applied to the primary transfer device 441. In this case, the photoconductor 41 is an image carrier with which the first roller 442a or the second roller 442b comes into contact. Also, the image creating device 4x and the laser scanning unit 40 are an example of a toner image forming device that forms the toner image on the surface of the photoconductor 41.

[0174] In this application example, the image sensor 5 reads the test image in the second area A2 on the surface of the photoconductor 41. In addition, the toner 9 constituting the test image formed on the surface of the photoconductor 41 is removed from the surface of the photoconductor 41 by the primary cleaning device 45. [Explanation of symbols]

[0175] 1: Main unit 3: Sheet transport device 4: Printing device 4x: Imaging device 5: Image sensor 8: Control device 8a: Print control unit 8b: Switching control section 8c: Parameter adjustment section 8d: Provisional setting processing section 8e: Measurement processing section 8f: Adjustment processing section 8g: Restoration processing section 8h: Judgment processing section 9: Toner 10: Image forming device 30: Paper feeder 40: Laser scanning unit 41: Photoreceptor 42: Charging device 43: Developing device 44: Transcription device 45: Primary cleaning device 46: Switching mechanism 46x: Drive shaft 47: Fixing device 48: Switching drive device 81 :CPU 82: RAM 83 :Secondary storage device 300: Sheet transport path 400: Toner container 440: Intermediate transfer belt 441: Primary transfer device 442: Secondary transfer device 442a: First roller 442b: 2nd roller 442x: First roller axis 442y: Rotation axis of the second roller 443: Secondary cleaning device 460: Movable support part 461a: First roller support member 461b: Second roller support member 462a: First protrusion 462b: Second convex part 463: First displacement member 463a: First slide support part 463b: Second slide support part 463c: First detection part 464a: First spring (first elastic member) 464b: Second spring (second elastic member) 465: Second displacement member 465a: First locking part 465b: Second locking part 465c : Recess 465d: Second detection part 465x: Sliding part 467a: First Restriction 467b: Second Restriction 468a: First detection sensor 468b: Second detection sensor 468c: 3rd detection sensor 468d: 4th detection sensor 468e: 5th detection sensor 480: Gear mechanism 481: Switching motor 482: Motor drive circuit 801 :Operator 802:Display device 4420: Transfer roller A1: 1st area A2:Second area D1: Sheet passing direction D2: Width direction N1: Transfer nip P1: Contact position

Claims

1. a switching mechanism that receives a driving force supplied from a single motor and switches between a plurality of transfer rollers that form a transfer nip portion in which a sheet is sandwiched between the transfer roller and an image carrier that carries a toner image; a provisional setting processing unit that provisionally sets a set value of the power supplied to the motor to a predetermined specific value; a measurement processing unit that measures a switching time of the transfer roller using the switching mechanism when the setting value is temporarily set by the temporary setting processing unit; an adjustment processing unit that adjusts the setting value based on a measurement result by the measurement processing unit; A transfer device comprising:

2. the adjustment processing unit adjusts the setting value each time a predetermined adjustment condition is satisfied. The transfer device according to claim 1 .

3. the switching mechanism performs a separation operation in which a first roller in contact with the image carrier is separated from the image carrier by receiving a driving force supplied from the motor rotating in one direction, and then performs a switching operation in which the roller facing the image carrier is switched from the first roller to a second roller by receiving a driving force supplied from the motor rotating in a direction opposite to that during the separation operation, and the second roller is brought into contact with the image carrier. The transfer device according to claim 1 .

4. the adjustment processing unit adjusts the set value of power supplied to the motor during the separating operation and the set value of power supplied to the motor during the switching operation separately. The transfer device according to claim 3 .

5. 5. An image forming apparatus comprising the transfer device according to claim 1, for forming an image on the sheet.

6. A power adjustment method executed in a transfer device having a switching mechanism that receives driving force supplied from a single motor and switches between a plurality of transfer rollers that form a transfer nip portion that sandwiches a sheet between the transfer roller and an image carrier that carries a toner image, the method comprising: a provisional setting step of provisionally setting a set value of power supplied to the motor to a predetermined specific value; a measuring step of measuring a switching time of the transfer roller using the switching mechanism when the set value is provisionally set by the provisional setting step; an adjustment step of adjusting the set value based on a measurement result from the measurement step; A power regulation method comprising:

Images