Image forming device

Abstract

The present invention discloses an image forming device. The image forming device includes: an intermediate transfer belt, a first transfer member, a second transfer member, a separation mechanism, and a control unit. The control unit includes a first mode in which both the first transfer member and the second transfer member are in a separated position; a second mode in which the first transfer member is in a contact position and the second transfer member is in a separated position; and a third mode in which both the first transfer member and the second transfer member are in a contact position. The control unit sequentially executes the first mode, the second mode, and the third mode. During a first switching operation from the second mode to the third mode, the rotational speed of the driving member is lower than the rotational speed of the driving member during a second switching operation from the first mode to the second mode.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, and more particularly to an electrophotographic image forming apparatus using an electrophotographic method. Background Art

[0002] There is known an image forming apparatus that outputs a color image in which a plurality of photosensitive drums carrying toner images on their surfaces are arranged in a line along the moving direction of the outer peripheral surface of an intermediate transfer belt (also referred to as a tandem type configuration).

[0003] Tandem image forming apparatuses use a primary transfer unit to sequentially transfer the toner images formed on the photosensitive drums to an intermediate transfer belt. Furthermore, a secondary transfer unit uses a secondary transfer unit to secondary transfer the toner images on the intermediate transfer belt to a sheet (recording material), thereby outputting a color image.

[0004] In such an image forming apparatus, during image formation, a primary transfer member is in contact with each photosensitive drum with an intermediate transfer belt interposed therebetween. On the other hand, during non-image formation, the primary transfer member is separated from the corresponding photosensitive drum (intermediate transfer belt) to prevent deformation of the intermediate transfer belt or to suppress friction with the photosensitive drum.

[0005] Specifically, the image forming apparatus discussed in Japanese Patent Application Publication No. 2014-77860 has a “standby position” where, during non-image formation, the intermediate transfer belt is separated from the photosensitive drum at stations for four colors (yellow, magenta, cyan, and black).

[0006] At the time of full-color image forming operation, the image forming apparatus has a "color station" in which the photosensitive drum and the intermediate transfer belt are in contact with each other via respective primary transfer members at stations of four colors.

[0007] In a monochrome (usually black) image forming operation, the image forming apparatus has a "monochrome position" in which the photosensitive drum and the intermediate transfer belt contact each other only at the black station and are separated from each other at the other three color stations.

[0008] The configuration discussed in Japanese Patent Application Laid-Open No. 2014-77860 has three “operating positions” regarding the primary transfer member.

[0009] Meanwhile, a driving unit or a contact / separation unit is required to switch the operation position among the above-mentioned three operation modes with respect to the primary transfer member.

[0010] When the contact / separation unit changes the contact state of the primary transfer member and the intermediate transfer belt to bring the intermediate transfer belt and the photosensitive drum into contact with each other, contact noise may be generated due to contact between the intermediate transfer belt and the primary transfer member in some cases. Summary of the Invention

[0011] An object of the present invention is to reduce contact noise occurring in contact / separation operation of a transfer member in a configuration capable of bringing a transfer member and an image bearing member into contact with or separating from each other.

[0012] According to one aspect of the present invention, an image forming apparatus includes: a first image bearing member configured to carry a colorant image; a second image bearing member configured to carry a colorant image different in color from the colorant image carried by the first image bearing member; an intermediate transfer member to which the colorant image carried by at least one of the first image bearing member and the second image bearing member is transferred; the first transfer member is arranged at a position corresponding to the first image bearing member, with the intermediate transfer member interposed therebetween, and the first transfer member is configured to transfer the colorant image from the first image bearing member to the intermediate transfer member; the second transfer member is arranged at a position corresponding to the second image bearing member, with the intermediate transfer member interposed therebetween, and the second transfer member is configured to transfer the colorant image from the second image bearing member to the intermediate transfer member; a moving unit configured to move at least one of the first transfer member and the second transfer member and capable of moving the first transfer member at least one of the first transfer component and the second transfer component is in contact with the intermediate transfer component, or at least one of the first transfer component and the second transfer component is separated from the intermediate transfer component; a driving component configured to move the moving unit; and a control unit configured to control the driving component to form a first state, a second state and a third state, the first state being a state in which both the first transfer component and the second transfer component are separated from the intermediate transfer component, the second state being a state in which the first transfer component is in contact with the intermediate transfer component and the second transfer component is separated from the intermediate transfer component, and the third state being a state in which both the first transfer component and the second transfer component are in contact with the intermediate transfer component, wherein the control unit is configured to control the driving component to move the moving unit and is capable of switching the first state to the second state and then switching the second state to the third state, and wherein the rotation speed of the driving component when the second state is switched to the third state is lower than the rotation speed of the driving component when the first state is switched to the second state.

[0013] Further features of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1is a conceptual diagram illustrating a longitudinal section of an image forming apparatus according to a first exemplary embodiment of the present invention.

[0015] Figure 2 is a perspective conceptual diagram illustrating an intermediate transfer unit in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0016] Figure 3 is a perspective conceptual diagram illustrating an intermediate transfer unit in a state where an intermediate transfer belt, a housing, and a cleaning device are removed in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0017] Figure 4 is a perspective conceptual diagram illustrating an intermediate transfer unit before being assembled in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0018] Figure 5 is a perspective conceptual diagram illustrating a drive shaft of a separation mechanism in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0019] Figure 6A is a conceptual diagram illustrating a positional relationship between a sliding member and a driving cam in a first mode according to the first exemplary embodiment of the present invention. Figure 6B is a conceptual diagram illustrating a positional relationship between the sliding member and the drive cam in the second mode according to the first exemplary embodiment of the present invention.

[0020] Figure 6C is a conceptual diagram illustrating a positional relationship between the sliding member and the drive cam in the third mode according to the first exemplary embodiment of the present invention.

[0021] Figure 7 is a conceptual diagram illustrating a state S1 in a standby mode of the intermediate transfer unit in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0022] Figure 8 is a conceptual diagram illustrating a state S2 in the monochrome mode of the intermediate transfer unit in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0023] Figure 9 is a conceptual diagram illustrating a state S3 in the full-color mode of the intermediate transfer unit in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0024] Figure 10 is a conceptual diagram illustrating a relationship between switching of an operation mode of a primary transfer roller and a change in a driving speed of a driving motor in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0025] Figure 11is a conceptual diagram illustrating a relationship between switching of an operation mode of a primary transfer roller and a change in a driving speed of a driving motor in an image forming apparatus according to a second exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0026] The image forming apparatus according to the present invention will be described using exemplary embodiments.

[0027] <Image Forming Apparatus>

[0028] Now refer to Figure 1 The configuration of an image forming apparatus configured to form a full-color image according to a first exemplary embodiment of the present invention is described.

[0029] Figure 1 is a conceptual diagram illustrating a longitudinal section of an image forming apparatus according to a first exemplary embodiment of the present invention.

[0030] Specifically, Figure 1 Shown is the overall configuration of a full-color laser beam printer P (hereinafter referred to as "printer P") equipped with an image forming unit configured to form toner images of four colors (yellow: Y, magenta: M, cyan: C, and black: B).

[0031] like Figure 1 As shown, the printer P (image forming apparatus) is equipped with four ink cartridges 1 (1Y, 1M, 1C, and 1B) arranged side by side in the horizontal direction. The ink cartridges 1 are attachable to or detachable from the apparatus body MB of the printer P.

[0032] The ink cartridge 1 is equipped with photosensitive drums 2 (2Y, 2M, 2C, and 2B) and charging rollers 3 (3Y, 3M, 3C, and 3B). The charging rollers 3 are arranged around the photosensitive drums 2 (image bearing members) and uniformly charge the surface of each photosensitive drum 2. The ink cartridge 1 also integrally includes developing rollers 4 (4Y, 4M, 4C, and 4B) that adhere toner to the photosensitive drums 2 to develop the image into a toner image. Toner of a predetermined color (not shown) serving as a developer is contained in each ink cartridge 1 and supplied to the surface of the corresponding developing roller 4 by the rotation of a supply roller 5 (5Y, 5M, 5C, and 5B).

[0033] An image forming operation to be performed on the recording material S (recording medium) will now be described.

[0034] The printer P rotates the pickup roller 6 counterclockwise while the pickup roller 6 is in contact with the recording material S contained in the cassette 7, and supplies the recording material S to the feed roller 8 and the separation roller 9. Thereafter, the recording material S is separated sheet by sheet by the separation roller 9 and then conveyed to the registration roller 10.

[0035] In synchronization with the operation of forming the toner image transferred by the registration roller 10 on the surface of the belt 100, the recording material S is conveyed to the secondary transfer roller 11 in contact with the surface of the belt 100 (intermediate transfer unit) of the intermediate transfer unit T. The intermediate transfer unit T will be described below.

[0036] At the same time, in synchronization with the operation of feeding the recording material S, the surfaces of the photosensitive drums 2 are uniformly charged by the respective charging rollers 3 while rotating in the clockwise direction. Furthermore, the photosensitive drums 2 are exposed by the respective laser scanners 12 (12Y, 12M, 12C, and 12B) that irradiate light according to image signals while rotating in the clockwise direction, and respective electrostatic latent images are formed.

[0037] The electrostatic latent image on the surface of each photosensitive drum 2 is visualized as a toner image by each developing roller 4. The photosensitive drum 2 is brought into contact with the belt 100 via four primary transfer rollers 101 (101Y, 101M, 101C, and 101B), and the toner image on the surface of each photosensitive drum 2 is transferred onto the belt 100 multiple times in a sequential manner by each primary transfer roller 101.

[0038] Thereafter, the toner image developed multiple times on the belt 100 is moved together with the belt 100 to the secondary transfer roller 11 by the belt drive roller 102, and is then secondarily transferred onto the recording material S. The toner image transferred onto the recording material S is conveyed to the fixing roller pair 13, which serves as a toner fixing unit, and is heated, pressed, and fixed to the recording material S while passing through the nip portion of the fixing roller pair 13. The recording material S is discharged to the discharge tray 15 at the top of the printer P via the discharge roller pair 14, with the toner image surface facing downward, thereby completing the image forming operation.

[0039] Each of the above operations is controlled by the control unit CU.

[0040]

Intermediate transfer unit T

[0041] Will refer to Figures 1 to 5 Description is made of the intermediate transfer unit T in the printer P. The intermediate transfer unit T is attachable to and detachable from the apparatus body MB.

[0042] Figure 2 1 is a perspective conceptual diagram illustrating an intermediate transfer unit T in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0043] Figure 3 is a perspective conceptual diagram illustrating an intermediate transfer unit in an image forming apparatus according to a first exemplary embodiment of the present invention in a state where an intermediate transfer belt, a housing, and a cleaning device are removed.

[0044] Figure 4is a perspective conceptual diagram illustrating an intermediate transfer unit before being assembled in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0045] Figure 5 is a perspective conceptual diagram illustrating a drive shaft of a separation mechanism in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0046] like Figures 1 to 3 As shown, the intermediate transfer unit T includes the above-mentioned belt 100 , four primary transfer rollers 101 , a belt driving roller 102 , a cleaning device 103 , a driven roller 104 , and a tension roller 105 in an integrated manner.

[0047] The primary transfer rollers 101 are arranged to face the photosensitive drums 2 on the inner side of the belt 100. A cleaning device 103 for cleaning transfer residual toner remaining on the surface of the belt 100 is arranged on the outer peripheral surface of the belt 100.

[0048] The belt 100 as an intermediate transfer member has an endless belt shape and is wound around a belt driving roller 102, a driven roller 104, and a tension roller 105 and stretched. The surface of the belt 100 can carry a toner image. Figure 1 As shown, when the belt driving roller 102 rotates in the counterclockwise direction, the belt 100 also rotates in the same direction in conjunction with the rotation of the belt driving roller 102 .

[0049] like Figure 2 As shown, the intermediate transfer unit T includes a driven member 106 to which the driving force for operating the four primary transfer rollers 101 is transmitted. Meanwhile, the printer P is equipped with a drive motor MT (driving member) coupled to continuously drive the fixing roller pair 13 of the printer P at a constant speed during image forming operations. In this exemplary embodiment, the printer P is configured to selectively transmit the distributed driving force from the drive motor MT to the driven member 106 using a clutch CL.

[0050] like Figure 2 and 3 As shown, sliding members 107 and 108 are arranged on both end sides of the primary transfer rollers 101 (101Y, 101M, 101C, and 101B) in the axial direction. The sliding member 107 is a member for bringing the primary transfer roller 101B (first transfer member) into contact with the belt 100 or separating the primary transfer roller 101B from the belt 100. The sliding member 108 is a member for bringing the primary transfer rollers 101Y, 101M, and 101C (second transfer member) into contact with the belt 100 or separating the primary transfer rollers 101Y, 101M, and 101C from the belt 100. That is, in this exemplary embodiment, the sliding members 107 and 108 constitute the separation mechanism 120 (moving unit) of the present invention.

[0051] The sliding members 107 and 108 are slidably supported by the housing 111 in a direction orthogonal to the axial direction of the primary transfer roller 101. The axial direction of the primary transfer roller 101 and the rotational axial direction of the belt 100 are identical to each other.

[0052] like Figure 4 and 5 As shown, each supporting member 110 includes a swing shaft 110a and a boss 110b, and each primary transfer roller 101 is supported by a housing 111 (not shown) via the swing shaft 110a so as to be able to swing. A transfer spring 112 is attached to each supporting member 110, and each primary transfer roller 101 is urged toward the corresponding photosensitive drum 2 by a predetermined elastic force of the transfer spring 112.

[0053] The separation drive shaft 106a is coaxially coupled to the driven member 106, and a drive cam 109 is coupled to each end side of the separation drive shaft 106a. The drive cam 109 also constitutes the separation mechanism 120 of the present invention. In other words, in this exemplary embodiment, the separation mechanism 120 (sliding members 107 and 108 and drive cam 109) as a moving unit is arranged on the intermediate transfer unit T together with the belt 100.

[0054] The drive cam 109 integrally includes drive cams 109a and 109b engaged with the slide member 107, and drive cams 109c and 109d engaged with the slide member 108. When the drive cam 109 rotates, the slide members 107 and 108 also slide in conjunction with the rotation of the drive cam 109.

[0055] The sliding member 107 includes a lifting / lowering cam 107a located at a predetermined position, and the sliding member 108 includes three lifting / lowering cams 108a located at respective predetermined positions. When the sliding members 107 and 108 slide, the lifting / lowering cams 107a and 108a of the supporting member 110 supporting the primary transfer rollers 101B, 101Y, 101M, and 101C and the boss 110b slide in contact with each other by the elastic force of the transfer spring 112.

[0056] The sliding members 107 and 108 are respectively equipped with sliding springs 113 and 114 , which apply elastic forces to oppose the sliding operations of the sliding members 107 and 108 .

[0057] According to this configuration, in the four primary transfer rollers 101 of the intermediate transfer unit T, the rotation of the driven member 106 and the drive cam 109 slides the sliding members 107 and 108 and swings each supporting member 110. Thus, the primary transfer rollers 101 are brought into contact with or separated from the belt 100.

[0058] In this manner, in the present exemplary embodiment, the printer P includes the belt 100 , the primary transfer roller 101B, the primary transfer rollers 101Y, 101M, and 101C, the separation mechanism 120 , and the drive motor MT that rotationally drives the separation mechanism 120 .

[0059] The primary transfer roller 101B may contact the belt 100 and correspond to a first color (blue (B)). Meanwhile, the primary transfer rollers 101Y, 101M, and 101C may contact the belt 100 and correspond to respective second colors (yellow (Y), magenta (M), and cyan (C)) different from the first color.

[0060] The separation mechanism 120 can move the first transfer rollers 101 to contact positions P1 where at least one of the four first transfer rollers 101 and the belt 100 are in contact with each other, and separation positions P2 where at least one of the four first transfer rollers 101 and the belt 100 are separated from each other.

[0061] [Operation Mode of Primary Transfer Roller 101]

[0062] Reference Figure 2 、 Figures 6A to 6C and Figures 7 to 9 Three operation positions (states) of the primary transfer roller 101 in the intermediate transfer unit T and switching of the operation mode (state) will be described.

[0063] Figures 6A to 6C Conceptual diagrams each showing a positional relationship between a sliding member and a drive cam in an image forming apparatus according to a first exemplary embodiment of the present invention.

[0064] Specifically, Figure 6A The positional relationship between the sliding members 107 and 108 and the driving cam 109 in the state S1 of the standby mode of the primary transfer roller 101 is shown. Figure 6B is a diagram showing the positional relationship in state S2 in the monochrome mode. Figure 6C is a diagram showing the positional relationship in state S3 in the full-color mode.

[0065] Figure 7 is a conceptual diagram illustrating a state S1 in a standby mode of the intermediate transfer unit T in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0066] Figure 8 is a conceptual diagram illustrating a state S2 in the monochrome mode of the intermediate transfer unit T in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0067] Figure 9 is a conceptual diagram illustrating a state S3 in the full-color mode of the intermediate transfer unit T in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0068] like Figures 7 to 9 The directions of rotation and operation of the components shown are indicated by arrows adjacent to the components.

[0069] like Figures 7 to 9 As shown, in this exemplary embodiment, the control unit CU has three modes. Therefore, the control unit CU can operate the primary transfer roller 101 in three operating positions: a "standby mode M1 (first mode)", a "monochrome mode M2 (second mode)", and a "full color mode M3 (third mode)" according to the image forming operation.

[0070] In the standby mode M1, a first state S1 can be formed in which all the primary transfer rollers 101 are in their respective separated positions. In the monochrome mode M2, a second state S2 can be formed in which the primary transfer roller 101B is in the contact position and the primary transfer rollers 101Y, 101M, and 101C are in their respective separated positions. In the full-color mode M3, a third state S3 can be formed in which all the primary transfer rollers 101 are in their respective contact positions.

[0071] As described above, in this exemplary embodiment, the image forming apparatus is configured to selectively transmit distributed driving force from the drive motor MT to the driven member 106 using the clutch CL. Specifically, in this exemplary embodiment, the image forming apparatus distributes the driving force from the drive motor MT that drives the fixing roller pair 13 and changes the contact positions of the respective primary transfer rollers 101, thereby enabling switching of operating modes. In this manner, by distributing the driving force from the drive motor MT of the fixing roller pair 13 for switching operating modes, the need for a drive unit solely for the contact positions of the primary transfer rollers 101 is eliminated, thereby preventing an increase in the size of the image forming apparatus.

[0072] In this exemplary embodiment, the order of the three operating positions is determined. A method (also referred to as a "rotation method") is employed in which the operating mode is switched from standby mode M1 to standby mode M1 again, sequentially through the other two modes. More specifically, in the image forming apparatus according to this exemplary embodiment, the order of switching the operating modes is set so that the image forming apparatus switches to full-color mode M3 after monochrome mode M2, taking into account the possibility of frequent output of "monochrome (black) images."

[0073] More specifically, according to this exemplary embodiment, the primary transfer roller 101 switches between the three operating positions, from standby mode, through monochrome mode, and finally to full-color mode, so that monochrome image formation begins before full-color image formation. Subsequently, the operating mode switches from full-color mode to standby mode. In other words, the control unit CU can sequentially operate the primary transfer roller 101 in standby mode M1, monochrome mode M2, and full-color mode M3.

[0074] like Figure 6A and Figure 7 As shown, the driving cam 109a positions the slide member 107 at the separated position in the right direction in the figure. In this state, the boss 110b of the support member 110 in the primary transfer roller 101B contacts the lifting / lowering cam 107a of the slide member 107 by the elastic force of the transfer spring 112, and the primary transfer roller 101B is located at the separated position above the belt 100.

[0075] The driving cam 109d also positions the slide member 108 in the rightward separation position in the figure. In this state, the bosses 110b of the support members 110 of the primary transfer rollers 101Y, 101M, and 101C are brought into contact with the three raising / lowering cams 108a of the slide member 108 by the elastic force of the transfer springs 112. The primary transfer rollers 101Y, 101M, and 101C are also located in the separation positions above the belt 100.

[0076] In this manner, all four primary transfer rollers 101 (101Y, 101M, 101C, and 101B) are also located at respective separation positions above the belt 100. This is referred to as a standby mode M1. The intermediate transfer unit T in this state is in a non-image forming state.

[0077] like Figure 6B and Figure 8 As shown, the slide member 108 is located at a separated position in the right direction in the figure, similar to the standby mode, and the primary transfer rollers 101Y, 101M, and 101C are located at respective separated positions above the belt 100 .

[0078] The slide member 107 is in the contact position in the left direction in the figure. In this state, the support member 110 in the primary transfer roller 101B is swung toward the belt 100, and the boss 110b is separated from the lifting / lowering cam 107a of the slide member 107. This brings the primary transfer roller 101B into contact with the belt 100, and the elastic force of the transfer spring 112 presses the belt 100 against the photosensitive drum 2B (first image bearing member).

[0079] In this manner, the three primary transfer rollers 101Y, 101M, and 101C are located at respective separation positions above the belt 100, and the primary transfer roller 101B is located at a contact position where it contacts the belt 100. This is referred to as a monochrome mode M2. The intermediate transfer unit T in this state is in a state during monochrome image formation.

[0080] By reference Figure 2The clutch CL transmits the driving force of the drive motor MT to the driven member 106 and rotates the drive cam 109 clockwise by 120 degrees, thereby switching the operating mode from the standby mode to the monochrome mode. As the drive cam 109 rotates, the drive cam 109b causes the sliding member 107 to slide to the contact position, and the boss 110b of the support member 110 in the primary transfer roller 101B separates from the lifting / lowering cam 107a of the sliding member 107.

[0081] The sliding of the sliding member 107 causes the boss 110b to slide into contact with the lifting / lowering cam 107a. At this time, the elastic force of the transfer spring 112 in the primary transfer roller 101B is released, and there is a high probability that a reverse input torque will be generated in the drive cam 109 via the sliding member 107. Therefore, the sliding spring 113 is arranged so as to apply an elastic force to resist the sliding operation of the sliding member 107.

[0082] Even if the driving cam 109 rotates 120 degrees, the sliding member 108 does not slide and is positioned at the separated position by the driving cam 109d.

[0083] like Figure 6B and Figure 9 As shown, similar to the monochrome mode, the slide member 107 is located at the separated position in the left direction of the figure. The primary transfer roller 101B contacts the belt 100 and presses the belt 100 against the photosensitive drum 2B by the elastic force of the transfer spring 112.

[0084] The slide member 108 is also located at the contact position to the left in the figure. In this state, the support members 110 of the three primary transfer rollers 101Y, 101M and 101C are swung toward the belt 100, and the bosses 110b are separated from the lifting / lowering cams 108a of the slide member 108.

[0085] This brings the three primary transfer rollers 101Y, 101M, and 101C into contact with the belt 100 , and presses the belt 100 against the photosensitive drums 2Y, 2M, and 2C as the second image bearing members by the elastic force of the respective transfer springs 112 .

[0086] In this manner, the state in which the four primary transfer rollers 101 (101Y, 101M, 101C, and 101B) are all located at respective contact positions with the belt 100 is referred to as full color mode M3. The intermediate transfer unit T in this state is in a state during full color image formation.

[0087] Similar to standby mode, Figure 2The clutch CL shown rotates the drive cam 109 120 degrees in the clockwise direction, thereby switching the operation mode from the monochrome mode to the full-color mode. When the drive cam 109 rotates, the drive cam 109c slides the sliding member 108 to the contact position, and the boss 110b of each supporting member 110 in each of the three primary transfer rollers 101Y, 101M, and 101C separates from the respective lifting / lowering cams 108a of the sliding member 108.

[0088] The sliding movement of the sliding member 108 causes the boss 110b to slide into contact with the lifting / lowering cam 107a. At this time, the elastic force of each of the transfer springs 112 in the three primary transfer rollers 101Y, 101M, and 101C is released, and there is a high probability that a reverse input torque will be generated in the drive cam 109 via the sliding member 108. Therefore, the sliding spring 114 is arranged so as to apply an elastic force in a direction parallel to the movement direction of the sliding operation of the sliding member 108.

[0089] Even if the driving cam 109a rotates 120 degrees, the sliding member 107 does not slide and is positioned at the separated position by the driving cam 109b.

[0090] Similar to switching the operating mode to another mode, Figure 2 The clutch CL shown rotates the drive cam 109 120 degrees in the clockwise direction, thereby switching the operation mode from the full-color mode to the standby mode. When the drive cam 109 rotates, the drive cams 109a and 109d slide the sliding members 107 and 108 in the right direction in the figure to the respective separation positions, and the image forming apparatus is switched to the standby mode again. Figure 7 Standby mode shown.

[0091] The sliding members 107 and 108 slide from their respective contact positions to their respective separation positions, whereby the bosses 110 b of the supporting member 110 in the primary transfer roller 101B come into contact with the lifting / lowering cams 107 a of the sliding member 107. The bosses 110 b of the corresponding supporting members 110 in the three primary transfer rollers 101Y, 101M, and 101C also come into contact with the three corresponding lifting / lowering cams 108 a of the sliding member 108.

[0092] At this time, elastic forces are applied to the four transfer springs 112 to lift the primary transfer roller 101 from the belt 100 , and the elastic forces of the slide springs 113 and 114 are released.

[0093] In this manner, each time the drive cam 109 rotates 120 degrees, the sliding members 107 and 108 slide to their respective separation positions or respective contact positions, thereby switching the operation mode of the primary transfer roller 101. More specifically, by one rotation of the drive cam 109, the image forming apparatus is moved from the standby mode M1 back to the standby mode M2 via the monochrome mode M2 and the full-color mode M3.

[0094] [Relationship between the primary transfer roller operation mode and the drive motor speed]

[0095] Now refer to Figure 10 The driving speed of the driving motor MT according to the first exemplary embodiment is described.

[0096] Figure 10 is a conceptual diagram illustrating a relationship between switching of the operation mode of the primary transfer roller 101 and changes in the driving speed of the driving motor MT in the image forming apparatus according to the first exemplary embodiment of the present invention.

[0097] In other words, Figure 10 The three operating positions of the primary transfer roller 101, the driving speed of the driving motor MT and Figure 1 The relationship between the elapsed times in the printer P is shown.

[0098] like Figure 10 As shown, the driving motor MT stops rotating during non-image forming (eg, when the printer P is on standby). In this state, the operation mode of the primary transfer roller 101 is in the standby mode.

[0099] The drive motor MT is controlled by the control unit CU to switch between two stable speeds: a drive speed SP1 (rotational speed) and a drive speed SP2 (rotational speed), during which the printer P performs image formation. In this exemplary embodiment, the drive speeds are assumed to have a relationship of SP1 > SP2.

[0100] The printer P rotates the drive motor MT at SP1 to start a monochrome image forming operation. Figure 1 As described above, the driving speed is a rotation speed required for the fixing roller pair 13 to rotate stably.

[0101] At a predetermined timing when the drive motor MT performs stable rotation at SP1, Figure 2The clutch CL shown in FIG1 distributes the driving force from the drive motor MT within a predetermined time and transmits the driving force to the driven member 106. Then, the sliding member 107 (not shown) in the separation mechanism 120 slides from the separation position to the contact position in a time period T12 (a time period for a second switching operation), and the printer P switches to the monochrome mode. The second switching operation (T12) is a switching operation from the standby mode M1 (state S1) to the monochrome mode M2 (state S2).

[0102] After the recording material S (not shown) on which a monochrome image has been formed through a series of image forming operations is discharged from the printer after the switching operation from the standby mode to the monochrome mode is performed, the control unit CU reduces the drive speed of the drive motor MT. Since the drive speed does not affect the monochrome image forming operation, the drive speed can be made as low as possible below SP1. SP1 is the drive speed for switching from the standby mode to the monochrome mode.

[0103] At a predetermined timing when the drive motor MT performs stable rotation at the speed SP2, the clutch CL distributes the driving force from the drive motor MT for a predetermined time and transmits the driving force to the driven member 106. Then, the sliding member 108 (not shown) in the separation mechanism 120 slides from the separation position to the contact position for a time period T23 (a time period for the first switching operation), and the printer P switches to the full-color mode. The first switching operation (T23) is a switching operation from the monochrome mode M2 (state S2) to the full-color mode M3 (state S3).

[0104] In the switching operation from the monochrome mode to the full-color mode, the driving speed of the driving motor MT is lower than the driving speed in the switching operation from the standby mode to the monochrome mode, and the time required for switching the operation mode of the primary transfer roller 101 (duration of a period of time) is related to T12. <T23。

[0105] In a monochrome image forming operation, by Figure 2 The clutch CL shown transmits the driving force of the drive motor MT to the driven member 106, thereby quickly performing the switching operation from the full-color mode to the standby mode. Then, the sliding member 107 (not shown) and the sliding member 108 (not shown) take time (a time period T31 of the third switching operation) to slide from their respective contact positions to their respective separation positions, and the printer P switches to the standby mode. After the printer P switches to the standby mode, the drive motor MT stops driving, and the printer P enters a non-image forming period, such as when the printer P is in standby mode. The third switching operation (T31) is a switching operation from the full-color mode M3 (state S3) to the standby mode M1 (state S1).

[0106] In other words, in this exemplary embodiment, the control unit CU performs control so that the rotation speed (SP2) of the driving motor MT at the moment T23 of the first conversion operation from the monochrome mode M2 to the full-color mode M3 is lower than the rotation speed (SP1) of the driving motor MT at the moment T12 of the second conversion operation from the standby mode M1 to the monochrome mode M2.

[0107] In conventional image forming device configurations, the contact noise generated when switching the operating mode from monochrome to full-color mode can, in some cases, be greater than the contact noise generated when switching the operating mode from standby mode to monochrome mode. In such cases, the contact noise generated when switching the operating mode from monochrome to full-color mode can cause discomfort to the user. The contact noise caused by the movement of the primary transfer roller is affected by the speed of the contact or separation operation. As the operating speed increases, the contact noise may become louder. On the other hand, there are limitations on reducing the operating speed to quickly initiate image forming operations.

[0108] On the other hand, in this exemplary embodiment, the operating speed of the separation mechanism 120 in full-color mode can be lowered than the operating speed in monochrome mode during the monochrome image forming operation in the intermediate transfer unit T of the printer P. With this configuration, the extended operating time when the multiple primary transfer rollers 101 are in contact with the belt 100 can reduce the operating speed, thereby reducing the contact noise generated when the primary transfer rollers 101 contact the belt 100. In other words, according to the configuration of this exemplary embodiment, in a configuration employing a rotation method, the contact noise associated with the movement of the primary transfer components, which occurs when the intermediate transfer belt contacts the photosensitive drum, can be reduced. In particular, this configuration can reduce (approximately) the contact noise generated when the operating mode switches from monochrome mode to full-color mode to the contact noise generated when the operating mode switches from standby mode to monochrome mode, thereby making the contact noise level associated with the mode switch constant (stable). This can mitigate the user's perception of the contact noise. Therefore, according to the present invention, the monochrome mode can be activated quickly, and contact noise can also be prevented during mode switching.

[0109] Since the drive speed of the drive motor MT, which is required to rotate at a stable speed during image formation, is reduced at a timing that does not affect the monochrome image forming operation, there is no need to increase the cost of arranging dedicated components such as soundproofing materials. When outputting a monochrome image, contact noise can be reduced without extending the first print output time.

[0110] In the present exemplary embodiment, the timing for reducing the driving speed of the driving motor MT may be the timing of discharging the recording material S from the fixing roller pair 13 .

[0111] Furthermore, the drive motor MT may be a motor that drives not only the fixing roller pair 13 but also the rollers for conveying the recording material S, the belt drive roller 102 in the intermediate transfer unit T, and the photosensitive drum 2, and rotates at a stable speed during the image forming operation. In this case, the timing for reducing the motor drive speed may be a timing when rotation at a stable speed is not required.

[0112] Now refer to Figure 11 The driving speed of the driving motor MT according to the second exemplary embodiment is described.

[0113] Figure 11 is a conceptual diagram illustrating a relationship between switching of the operation mode of the primary transfer roller 101 and changes in the driving speed of the driving motor MT in the image forming apparatus according to the second exemplary embodiment of the present invention.

[0114] Figure 11 The relationship among the three operating positions of the primary transfer roller 101 , the driving speed of the driving motor MT, and the elapsed time in the printer P is shown.

[0115] Since the second exemplary embodiment differs from the first exemplary embodiment only in control for changing the driving speed of the driving motor MT, description of the configuration of the second exemplary embodiment is omitted.

[0116] like Figure 11 As shown, the driving motor MT stops rotating during non-image forming (eg, when the printer P is in a standby state). In this state, the operation mode of the primary transfer roller 101 is a standby mode.

[0117] Similar to the first exemplary embodiment, the driving of the driving motor MT is controlled to switch between two stable speeds, the driving speed SP1 and the driving speed SP2, during which the printer P performs image formation. The driving speeds are assumed to have a relationship of SP1>SP2.

[0118] The relationship between the driving speed of the driving motor MT and the elapsed time in the switching operation from the standby mode to the full-color mode via the monochrome mode is similar to the relationship described in the first exemplary embodiment.

[0119] During the shift operation from full-color mode to standby mode, the drive speed of the drive motor MT is increased from SP2 to SP1. Then, the slide member 107 (not shown) and the slide member 108 (not shown) slide from their respective contact positions to their respective separation positions over a period of time T310 (a time period for the third shift operation), and the printer P shifts to standby mode. The third shift operation (T310) is a shift operation from the full-color mode M3 (state S3) to the standby mode M1 (state S1).

[0120] When changing from the full-color mode to the standby mode, the driving speed of the driving motor MT is higher than that in the first exemplary embodiment, and the relationship of the time required to switch the operation mode from the full-color mode to the standby mode (the duration of a period of time) is T31 < T310. Similar to the first exemplary embodiment, after the printer P changes to the standby mode, the driving motor MT stops driving, and the printer P is in a non-image forming period (for example, when the printer P is in the standby state).

[0121] In the present exemplary embodiment, the operating speed of the separating mechanism 120 in the full-color mode can be made lower than that in the monochrome mode, so that the contact noise generated when the plurality of primary transfer rollers 101 contact the belt 100 can be reduced.

[0122] In particular, in the second exemplary embodiment, the time for the transformation operation from the full-color mode to the standby mode can be made shorter than that in the first exemplary embodiment, so that the time from the start of image formation to returning to the standby state can be shortened.

[0123] In the present exemplary embodiment, the driving speed of the driving motor MT increased from SP2 during the transformation from the full-color mode to the standby mode is not limited to SP1, and only needs to be higher than SP2.

[0124] According to the present invention, in the monochrome image forming operation of the color image forming apparatus, by operating a plurality of primary transfer members by the separating mechanism, the contact noise generated when the intermediate transfer belt contacts the photosensitive drum can be reduced.

[0125] There is no need to increase costs such as arranging dedicated components to reduce contact noise, and the contact noise can be reduced without causing performance degradation such as extending the first print output time for outputting monochrome images.

[0126] Although the present invention has been described with reference to the exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the following claims should be interpreted as widely as possible to cover all such modifications and equivalent structures and functions.

Claims

1. An image forming apparatus, comprising: a first image bearing member configured to bear a toner image; a second image bearing member configured to bear a toner image different in color from the toner image carried by the first image bearing member; an intermediate transfer member to which the toner image carried by at least one of the first image bearing member and the second image bearing member is transferred; a first transfer member disposed at a position corresponding to the first image bearing member with the intermediate transfer member interposed therebetween and configured to transfer the toner image from the first image bearing member to the intermediate transfer member; a second transfer member disposed at a position corresponding to the second image bearing member with the intermediate transfer member interposed therebetween and configured to transfer the toner image from the second image bearing member to the intermediate transfer member; a moving unit configured to move at least one of the first transfer member and the second transfer member and capable of bringing at least one of the first transfer member and the second transfer member into contact with the intermediate transfer member or separating at least one of the first transfer member and the second transfer member from the intermediate transfer member; a driving member configured to move the mobile unit; as well as a control unit configured to control the driving member to form a first state, a second state, and a third state, the first state being a state in which both the first transfer member and the second transfer member are separated from the intermediate transfer member, the second state being a state in which the first transfer member is in contact with the intermediate transfer member and the second transfer member is separated from the intermediate transfer member, and the third state being a state in which both the first transfer member and the second transfer member are in contact with the intermediate transfer member, The control unit is configured to control the driving component to move the moving unit, and is capable of switching the first state to the second state, and then switching the second state to the third state, and Wherein, the rotation speed of the driving component when the second state is switched to the third state is lower than the rotation speed of the driving component when the first state is switched to the second state.

2. The image forming apparatus according to claim 1, in, The control unit is capable of performing an image forming operation in the second state or the third state, and Herein, the control unit is configured to perform control so that a rotation speed of the driving member when the third state is switched to the first state is equal to a rotation speed of the driving member when the image forming operation in the third state is completed.

3. The image forming apparatus according to claim 1, in, The control unit is capable of performing an image forming operation in the second state or the third state, and Here, the control unit is configured to perform control so that a rotation speed of the driving member when the third state is switched to the first state is higher than a rotation speed of the driving member when the image forming operation in the third state is completed.

4. The image forming apparatus according to claim 1 , further comprising: a transport device configured to transport the recording medium; as well as a fixing device configured to fix the toner image onto the recording medium, Here, the driving member is a member configured to transmit a driving force to any one of the conveying device, the fixing device, the first image bearing member, the second image bearing member, and the intermediate transfer member.

5. The image forming apparatus according to claim 4, wherein The driving component is a component configured to transmit driving force to the fixing device.

6. The image forming apparatus according to claim 4, in, The control unit is capable of performing an image forming operation in the second state or the third state, and The rotation speed of the driving component when the first state is switched to the second state is equal to the rotation speed of the driving component when the image is formed in the second state.

7. The image forming apparatus according to claim 1, wherein The first image bearing member carries a black toner image.

8. The image forming apparatus according to any one of claims 1 to 7, in, The mobile unit includes: a first moving member configured to move the first transfer member relative to the intermediate transfer member; a second moving member configured to move the second transfer member relative to the intermediate transfer member; and a cam member configured to move the first moving member and the second moving member, and Here, the driving member is a member configured to rotationally drive the cam member.

9. The image forming apparatus according to claim 8, wherein The cam member rotates one revolution in a predetermined rotation direction, shifting the state from the first state via the second state and the third state back to the first state.

10. The image forming apparatus according to claim 8, wherein The moving unit and the intermediate transfer member are arranged in an intermediate transfer unit, and the intermediate transfer unit is configured to be detachably attached to an apparatus body of the image forming apparatus.

Images