Image forming apparatus and control method thereof

Abstract

To efficiently loosen toner in a new cartridge when the cartridge is mounted in a housing and prevent unnecessary agitation of the toner.SOLUTION: A control unit of an image forming apparatus rotates a first motor at a first speed to rotate an agitator when forming an image on a sheet. When a power supply is turned on or when a cover is moved from an open position to a closed position, the control unit executes determination processing (S140) of determining whether a new cartridge is included in a plurality of cartridges; when the new cartridge is included (S140, Yes), executes initial agitation processing (S150) of agitating the toner with the agitator by rotating the first motor at a second speed slower than the first speed; and when the new cartridge is not included (S140, No), does not execute the initial agitation processing.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to an electrophotographic image forming apparatus and a control method thereof. [Background technology]

[0002] In electrophotographic image forming devices, when the power is turned on or the cover is opened and closed, an initialization operation is performed by rotating the motor for a predetermined time. When a new cartridge is installed, an image forming device is known that rotates the motor at a low speed to perform the initialization operation (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-186369 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when toner is stored for a long period of time or is subjected to vibration during transportation, the fluidity of the toner decreases and the toner may become solidified. When loosening the solidified toner, there is a problem in that the load required to stir the toner is large. On the other hand, in cartridges that are not new, the toner is often not solidified, and stirring it unnecessarily deteriorates the toner and wastes electricity. SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to efficiently loosen the toner in a cartridge when a new cartridge is attached, and to prevent the toner from being unnecessarily stirred. [Means for solving the problem]

[0005] The image forming device for solving the above-mentioned problems includes a housing having an opening, a photosensitive drum, a cover movable between a closed position that closes the opening and an open position that opens the opening, a developing roller, a storage chamber that stores toner, and an agitator that agitates the toner, and is equipped with a plurality of cartridges that are attached to the housing through the opening, a first motor that rotates the agitator, and a control unit. When forming an image on a sheet, the control unit rotates the first motor at a first speed to rotate the agitator, and when the power is turned on or the cover is moved from the open position to the closed position, executes a determination process to determine whether or not a new cartridge is included among the multiple cartridges, and if a new cartridge is included, executes an initial mixing process to mix the toner with the agitator by rotating the first motor at a second speed slower than the first speed, and if a new cartridge is not included, does not execute the initial mixing process.

[0006] According to this configuration, when a new cartridge is installed, the first motor is rotated at the second speed, which is slower than the speed during image formation, to perform the initial stirring process. This allows the torque of the first motor to be increased, making it easier to loosen the toner even if it has solidified. In addition, if only cartridges that are not new are installed, the initial mixing process is not executed, which prevents unnecessary mixing of toner, thereby preventing toner deterioration and unnecessary power consumption.

[0007] Each of the cartridges may have a memory in which identification data indicating whether or not the cartridge is new is recorded. In this case, the control unit can execute the determination process by reading the identification data from the memory.

[0008] In this way, by reading out the identification data from the memory and performing the determination process, there is no need to operate the first motor in the determination process.

[0009] The image forming apparatus may further include a separation mechanism capable of moving the developing roller between a contact position where the developing roller contacts the photosensitive drum and a separation position where the developing roller is separated from the photosensitive drum. In this case, when the power is turned on or when the cover is moved from the open position to the closed position, it is preferable that the control unit executes an initial separation process for rotating the first motor at a first speed to position the developing rollers of the multiple cartridges at the separation position before executing the determination process.

[0010] According to this configuration, the initial mixing process can be executed with the developing roller in the separated position, so that the load on the first motor during the initial mixing process can be reduced. Furthermore, if the cartridge has a memory, the determination process is performed with the developing roller in the separated position, so that even if the user has not correctly attached the cartridge, it is easy to correctly read the identification data from the memory.

[0011] The image forming apparatus may further include a drive transmission mechanism that transmits the drive force of the first motor to the separation mechanism. The developing roller is driven by the first motor, and the drive transmission mechanism may be configured to transmit the drive force to the agitator, the developing roller, and the separation mechanism when the first motor rotates in a first direction, and to transmit the drive force to the separation mechanism without transmitting the drive force to the agitator and the developing roller when the first motor rotates in a second direction opposite to the first direction. The control unit may then rotate the first motor in the second direction in the initial separation process.

[0012] According to this configuration, the agitator and the developing roller do not rotate during the initial spacing process, so that the load on the first motor during the initial spacing process can be reduced and deterioration of the toner and the developing roller can be suppressed.

[0013] The image forming apparatus may further include a second motor that rotates the photosensitive drum. The control unit may rotate the first motor while stopping the second motor, and execute the initial stirring process.

[0014] The image forming apparatus may further include a fixing unit having a rotating body that fixes a toner image formed on a sheet, and a third motor that rotates the rotating body. The control unit may then rotate the first motor while stopping the third motor, thereby executing an initial stirring process.

[0015] The image forming apparatus may further include a fixing unit having a belt disposed opposite the photosensitive drum and a rotating body that fixes a toner image formed on a sheet, a second motor that rotates the photosensitive drum and the belt, and a third motor that rotates the rotating body. The control unit may then rotate the first motor while stopping the second motor and the third motor, thereby executing the initial stirring process.

[0016] In this case, the control unit may execute the initial separation process by rotating the first motor while stopping the second motor and the third motor.

[0017] The control method of the image forming apparatus of the present invention, which solves the above-mentioned problems, is a control method of an image forming apparatus including a housing having an opening, a photosensitive drum, a cover movable between a closed position where the opening is closed and an open position where the opening is opened, a developing roller, a storage chamber for storing toner, and an agitator for agitating the toner, and a plurality of cartridges attached to the housing through the opening. In this control method, when forming an image on a sheet, the agitator is rotated at a third speed, and when the power is turned on or the cover is moved from the open position to the closed position, a determination process is performed to determine whether or not a new cartridge is included in the plurality of cartridges, and if a new cartridge is included, an initial agitation process in which the agitator is rotated to agitate the toner is performed at a fourth speed slower than the third speed, and if a new cartridge is not included, the initial agitation process is not performed.

[0018] According to this control method, when a new cartridge is installed, when the power is turned on or when the cover is moved from the open position to the closed position, the agitator is rotated at a fourth speed slower than that during image formation to perform the initial mixing process, so that even if the toner is solidified, it is easy to loosen the toner. Also, when only a cartridge that is not new is installed, the initial mixing process is not performed, so unnecessary mixing of the toner is suppressed. This makes it possible to suppress toner deterioration and unnecessary power consumption.

[0019] In the above-mentioned control method, the image forming apparatus further includes a belt arranged opposite the photosensitive drum, and a fixing device having a rotating body that fixes a toner image formed on a sheet, and when forming an image on the sheet, the photosensitive drum, the belt, and the agitator are rotated, and when performing the initial stirring process, the agitator is rotated without rotating the photosensitive drum and the belt.

[0020] The image forming apparatus of the present invention which solves the above-mentioned problems includes a housing having an opening, a photosensitive drum, a cover movable between a closed position which closes the opening and an open position which opens the opening, a developing roller, a storage chamber which contains toner, and an agitator which agitates the toner, and is equipped with a plurality of cartridges which are attached to the housing through the opening, a first motor which rotates the agitator, a separation mechanism which can move the developing roller between a contact position where it contacts the photosensitive drum and a separated position which is separated from the photosensitive drum, and a control unit. When the power is turned on or the cover is moved from the open position to the closed position, the control unit executes an initial separation process in which the first motor is rotated to position the developing rollers of the multiple cartridges in the separated position, and after executing the initial separation process, executes a determination process to determine whether or not a new cartridge is included among the multiple cartridges, and if a new cartridge is included, executes an initial mixing process in which the toner is mixed with an agitator by rotating the first motor, and if a new cartridge is not included, does not execute the initial mixing process.

[0021] According to this configuration, when a new cartridge is installed, the determination process is performed after the initial separation process, and when a new cartridge is included, the initial mixing process is performed. Therefore, in the initial mixing process, the developing roller is located at the separation position, so that the load on the first motor can be reduced, and even if the toner is solidified, the toner can be easily loosened. In addition, when only cartridges that are not new are installed, the initial mixing process is not performed, so that unnecessary mixing of the toner is suppressed. This suppresses toner deterioration and unnecessary power consumption. Effect of the Invention

[0022] According to the present invention, when a new cartridge is installed, the torque of the first motor is increased or the load of the first motor is decreased, so that the toner can be easily loosened even if it is solidified. Also, when only a cartridge that is not new is installed, the initial stirring process is not executed, so that unnecessary stirring of the toner is suppressed. [Brief description of the drawings]

[0023] [Figure 1] 1 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment; [Diagram 2] FIG. 2 is a perspective view of a drawer, a cam, and a cam follower. [Diagram 3] 1A is a perspective view of a developing cartridge, and FIG. [Figure 4] 5A and 5B are schematic diagrams illustrating the sliding member when the cam follower is located at the standby position and the cam follower is located at the protruding position, as viewed from above around the developing cartridge. [Diagram 5] FIG. 2 is a diagram illustrating the connection of a mechanism in which each motor drives each member. [Figure 6] FIG. 1A is a perspective view of the yellow, magenta, and cyan cams as viewed from the first surface side, and FIG. [Figure 7]1A is an exploded perspective view of the clutch as viewed from the sun gear side, and FIG. 1B is an exploded perspective view of the clutch as viewed from the carrier side. [Figure 8] FIG. 1A is an exploded perspective view of the lever, FIG. 1B is a diagram showing a state in which the rotation of the first lever is restricted by the rotation restricting part, and FIG. 1C is a diagram showing a state in which the first lever is swung relative to the second lever. [Figure 9] 1A is a perspective view showing the cam, the cam follower, and the release member when the cam rotates forward and the developing roller is in the contact position, and FIG. [Figure 10] 1A is a perspective view showing the cam, the cam follower, and the release member when the cam rotates forward and the developing roller is in the separated position, and FIG. [Figure 11] FIG. 11 is a side view showing the cam, cam follower and release member, in which (a) shows the cam rotating in the reverse direction so that the developing roller is in the separated position and the first lever is in the swing position, and (b) shows the cam rotating in the forward direction from the position in (a) and then stopping. [Figure 12] 5 is a flowchart showing a process of the control unit when the power is turned on or the cover is closed. [Figure 13] 13 is a flowchart of a memory reading process. [Figure 14] 4 is a timing chart illustrating the operation of each part when the power is turned on and a new developing cartridge is installed. [Figure 15] 4 is a timing chart illustrating the operation of each part when the power is turned on, showing the case where only a non-new developing cartridge is installed. [Figure 16] 5 is a timing chart illustrating the operation of each part when the power is turned on, showing a modified example in which a new developing cartridge is attached. [Figure 17] 5 is a timing chart illustrating the operation of each section when the power is turned on, showing a modified example in which only a non-new developing cartridge is attached. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] As shown in Fig. 1, the image forming apparatus 1 according to the embodiment is a color printer and mainly includes a housing 10, a cover 11, a sheet supply unit 20, an image forming unit 30, and a control unit 2. For convenience, in this specification, directions such as front and rear will be described with the left side of Fig. 1 where the sheet tray 21 is pulled out as the front. That is, the left side of Fig. 1 is the front, the right side is the rear, the top and bottom are the top and bottom, the front side of the paper in Fig. 1 is the right, and the back side of the paper is the left.

[0025] The housing 10 has an opening 10A on the front side. The cover 11 is movable between a closed position shown by a solid line in which the opening 10A is closed, and an open position shown by a virtual line in which the opening 10A is opened. The housing 10 is provided with a cover sensor (not shown) that detects the open / closed state of the cover 11, and the control unit 2 can determine the open / closed state of the cover 11 based on a signal from the cover sensor.

[0026] The sheet supply unit 20 is provided in the lower part of the housing 10, and includes a sheet tray 21 that stores sheets S, and a supply mechanism 22 that supplies the sheets S from the sheet tray 21 to the image forming unit 30. The sheet tray 21 is configured to be removable by pulling it out to the left side of FIG. 1 from the housing 10. The supply mechanism 22 is provided in the front part of the housing 10, and includes a feed roller 23, a separation roller 24, a separation pad 25, and a registration roller 27. The sheet S in this specification is a medium on which the image forming apparatus 1 can form an image, and includes plain paper, envelopes, postcards, thin paper, thick paper, glossy paper, resin sheets, stickers, etc.

[0027] In the sheet supply unit 20, the sheets S in the sheet tray 21 are fed by a feed roller 23, and then the sheets S are separated one by one between a separation roller 24 and a separation pad 25. Thereafter, the leading edge position of the sheet S is regulated by the registration rollers 27 that are in a stopped state of rotation, and then the sheet S is supplied to the image forming unit 30 by the rotation of the registration rollers 27 .

[0028] The image forming section 30 includes an exposure device 40, a drawer 90 (see FIG. 2) having a plurality of photosensitive drums 50, a plurality of developing cartridges 60 as an example of a plurality of cartridges, a conveying device 70, and a fixing unit 80.

[0029] The exposure device 40 includes a laser diode, a deflector, a lens, and a mirror (not shown). The exposure device 40 is configured to emit a plurality of laser beams that expose the plurality of photosensitive drums 50 and scan the surfaces of the photosensitive drums 50.

[0030] The photosensitive drums 50 include a photosensitive drum 50Y corresponding to yellow, a photosensitive drum 50M corresponding to magenta, a photosensitive drum 50C corresponding to cyan, and a photosensitive drum 50K corresponding to black. In this specification and drawings, the members provided corresponding to each color of yellow, magenta, cyan, and black are indicated by Y, M, C, and K, respectively, when the colors are to be distinguished from one another.

[0031] The developing cartridge 60 has a developing roller 61 that supplies toner to each photosensitive drum 50. Specifically, the developing cartridges 60Y, 60M, 60C, and 60K have developing rollers 61Y, 61M, 61C, and 61K corresponding to the photosensitive drums 50Y, 50M, 50C, and 50K of the Y, M, C, and K colors, respectively.

[0032] Each of the multiple developing cartridges 60 has a case 63 having a chamber for storing toner, and an agitator 67 for agitating the toner stored in the chamber. The developing roller 61 and the agitator 67 of each developing cartridge 60 are connected by a gear (not shown), so that when the developing roller 61 rotates, the agitator 67 also rotates simultaneously. Each developer cartridge 60 also has a memory 68 on one side wall on the front side. The memory 68 stores identification data indicating whether the developer cartridge 60 is new or not.

[0033] The developing roller 61Y, the developing roller 61M, the developing roller 61C, and the developing roller 61K are disposed in this order from the upstream side to the downstream side in the moving direction of the sheet S.

[0034] Each developing cartridge 60 is movable between a contact position, shown by a solid line in Figure 1, where the developing roller 61 contacts the corresponding photosensitive drum 50, and a separation position, shown by a virtual line in Figure 1, where the developing roller 61 is separated from the corresponding photosensitive drum 50.

[0035] As shown in Fig. 2, the photosensitive drum 50 is rotatably supported by a drawer 90. The drawer 90 also detachably supports each developing cartridge 60. The drawer 90 is detachable from the housing 10 through an opening 10A formed by opening a cover 11 (see Fig. 1) of the housing 10. The drawer 90 includes a pair of side frames 91 spaced apart in the axial direction of the photosensitive drum 50, a connecting frame 92 connecting front portions of the pair of side frames 91, and a connecting frame 93 connecting rear portions of the pair of side frames 91. The pair of side frames 91 includes a right side frame 91R and a left side frame 91L. The drawer 90 is provided with chargers 52 (see FIG. 1) arranged opposite each photosensitive drum 50 for charging the photosensitive drums 50.

[0036] Although detailed structural illustration is omitted, the pair of side frames 91 support the end of the photosensitive drum 50. One of the side frames 91, here the left side frame 91L, has a second opening 91A. The second opening 91A is formed as a notch recessed downward in the upper edge of the side frame 91L. As a result, the second opening 91A penetrates the side frame 91L from left to right, allowing a cam follower 170, which will be described later, to enter therethrough. Although not shown, the drawer 90 has a first relay contact that contacts the contact of the memory 68 of each developing cartridge 60, and a second relay contact that is electrically connected to the control unit 2 of the main body. The first relay contact and the second relay contact are connected by wiring. This allows each memory 68 to communicate with the control unit 2 via the first relay contact and the second relay contact.

[0037] The image forming apparatus 1 has a separation mechanism that moves each developing roller 61 between a contact position where the developing roller 61 contacts a corresponding one of the multiple photosensitive drums 50 and a separation position where the developing roller 61 is separated from the photosensitive drum 50. The separation mechanism is provided corresponding to each of Y, M, C, and K.

[0038] Specifically, each spacing mechanism includes a cam 150 (150Y, 150M, 150C, 150K) that rotates around an axis parallel to the rotation axis 61X of the developing roller 61 (see FIG. 1), a support shaft 179, and a cam follower 170. The cam 150 is rotatable in the direction of the rotation axis of the developing roller 61 (hereinafter, simply referred to as the “rotation axis direction”). ) has a first cam portion 152 protruding therefrom.

[0039] The support shaft 179 is a shaft that extends long in the left-right direction and is provided on a side frame (not shown) of the housing 10.

[0040] The cam follower 170 engages with the support shaft 179, and is slidable along the axial direction of the support shaft 179 and rotatable around the axis of the support shaft 179. The cam follower 170 has a contact portion 172 that is capable of coming into contact with the first cam portion 152. Specifically, as the cam 150 rotates, the cam follower 170 is guided by the first cam portion 152 and can slide between a protruding position shown in FIG. 4(b) that positions the developing roller 61 in the separated position and a standby position shown in FIG. 4(a) that positions the developing roller 61 in the contact position.

[0041] When the cam follower 170 is in the protruding position, it enters the second opening 91A and presses the developing cartridge 60 to position the developing roller 61 in the separated position, and when it is in the standby position, it exits the second opening 91A and positions the developing roller 61 in the contact position.

[0042] Returning to Fig. 2, the cam 150 and the cam follower 170 are provided corresponding to each developing cartridge 60. The cam 150 and the cam follower 170 are disposed on the outer side in the left-right direction of the left side frame 91L. The detailed structures of the cam 150 and the cam follower 170 will be described later.

[0043] The drawer 90 is provided with contact portions 94 on the upper portions of the side frames 91R, 91L, which come into contact with the slide members 64 described below. The contact portions 94 are formed of rollers that are rotatable about axes along a third direction (vertical direction) that is perpendicular to both a first direction parallel to the axial direction of the photosensitive drums 50 and a second direction in which the photosensitive drums 50 are arranged.

[0044] The drawer 90 also includes pressing members 95 provided in correspondence with each of the developer cartridges 60. The pressing members 95 are provided at both axial ends of the photosensitive drum 50 for each of the developer cartridges 60. The pressing members 95 are biased rearward by springs 95A (see FIGS. 4(a) and 4(b)). When the developer cartridge 60 is attached to the drawer 90, the pressing members 95 press the protrusions 63D of the developer cartridge 60 to bring the developing roller 61 into contact with the corresponding photosensitive drum 50.

[0045] As shown in FIGS. 3(a) and 3(b), the developing cartridge 60 includes the above-mentioned case 63, a slide member 64, and a coupling 65. The coupling 65 engages with a coupling shaft 119, which will be described later, and receives a rotational driving force from the coupling shaft 119.

[0046] The slide member 64 is a member that is slidable in the direction of the rotation axis with respect to the case 63. The slide member 64 is slidable in the direction of the rotation axis by being pressed by the cam follower 170.

[0047] 4(a) and (b), the slide member 64 includes a shaft 191, a first contact member 192, and a second contact member 193. The first contact member 192 is fixed to one end of the shaft 191, and the second contact member 193 is fixed to the other end of the shaft 191.

[0048] The shaft 191 is disposed through a hole formed in the case 63 and extending in the direction of the rotation axis, and is supported by the case 63 so as to be slidable.

[0049] The first contact member 192 has a pressing surface 192A which is an end surface in the direction of the rotation axis, and an inclined surface 192B which is inclined with respect to the direction of the rotation axis. The pressing surface 192A is the surface that is pressed by the cam follower 170. When the slide member 64 is pressed in the rotation axis direction by the cam follower 170, the inclined surface 192B comes into contact with the contact portion 94 of the drawer 90 to urge the developer cartridge 60 in a direction parallel to the moving direction of the sheet S, thereby moving the developer cartridge 60 (see FIG. 4(b)). As the inclined surface 192B moves from one end of the shaft 191 to the other end, it is inclined so as to be positioned in the direction (forward) from the photosensitive drum 50 toward the corresponding developing roller 61 in the second direction.

[0050] The second abutting member 193 has an inclined surface 193B that is inclined similarly to the inclined surface 192B of the first abutting member 192. When the slide member 64 is pressed in the rotation axis direction by the cam follower 170, the inclined surface 193B also abuts against the abutted portion 94 of the drawer 90, and urges the developer cartridge 60 in a direction parallel to the moving direction of the sheet S, thereby moving the developer cartridge 60 (see FIG. 4(b)).

[0051] A spring 194 that biases the slide member 64 toward one side in the rotation axis direction, in this case, toward the left side, is disposed between the first contact member 192 and the case 63. The spring 194 is a compression coil spring, and is disposed outside the shaft 191 so that the shaft 191 passes through its coil.

[0052] Returning to FIG. 1, the conveying device 70 is provided between the sheet tray 21 and the photosensitive drums 50. The conveying device 70 includes a driving roller 71, a driven roller 72, a conveying belt 73 as an example of a belt formed of an endless belt, and four transfer rollers 74. The conveying belt 73 is stretched between the driving roller 71 and the driven roller 72, and its outer surface is disposed facing each of the photosensitive drums 50. Each transfer roller 74 is disposed inside the conveying belt 73 so as to sandwich the conveying belt 73 between each of the photosensitive drums 50. The conveying device 70 conveys the sheet S by moving the conveying belt 73 with the sheet S placed on the outer peripheral surface on the upper side, and at this time, transfers the toner images of the multiple photosensitive drums 50 onto the sheet S.

[0053] Further, a belt cleaner 75 for cleaning the surface of the conveyor belt 73 is provided below the conveyor belt 73. The belt cleaner 75 has a case 75A and a cleaning roller 75B. The cleaning roller 75B is in contact with the surface of the conveyor belt 73 and removes foreign matter such as toner from the surface of the conveyor belt 73. The foreign matter removed by the cleaning roller 75B is accumulated in the case 75A.

[0054] The fixing device 80 is provided behind the photosensitive drum 50 and the conveying device 70. The fixing device 80 has a heating roller 81 as an example of a rotating body, and a pressure roller 82 arranged opposite to the heating roller 81. The heating roller 81 has a heater 81A (a halogen lamp in this embodiment) for heating the heating roller 81 inside. The temperature of the heating roller 81 can be controlled by controlling the output of the heater 81A. As shown in FIG. 5, the fixing device 80 has a nip pressure adjustment mechanism 85. The nip pressure adjustment mechanism 85 has an arm 86 and a nip pressure adjustment cam 87. As shown in FIG. 5, the pressure roller 82 is supported by the swingable arm 86. The nip pressure adjustment cam 87 rotates to swing the arm 86, thereby changing the axis distance between the heating roller 81 and the pressure roller 82. This makes it possible to adjust the nip pressure between the heating roller 81 and the pressure roller 82.

[0055] Returning to FIG. 1, above the fixing unit 80, a conveying roller 15 is provided, and above the conveying roller 15, a discharge roller 16 is provided.

[0056] In the image forming unit 30 thus configured, first, the surface of each photosensitive drum 50 is uniformly charged by the charger 52, and then exposed to light irradiated from the exposure device 40. As a result, an electrostatic latent image based on image data is formed on each photosensitive drum 50.

[0057] The toner in the case 63 is carried on the surface of the developing roller 61, and is supplied to the electrostatic latent image formed on the photosensitive drum 50 when the developing roller 61 faces and contacts the photosensitive drum 50. As a result, a toner image is formed on the photosensitive drum 50.

[0058] Next, the sheet S supplied onto the conveyor belt 73 passes between each photosensitive drum 50 and each transfer roller 74, so that the toner images formed on each photosensitive drum 50 are transferred onto the sheet S. Then, the sheet S passes between a heating roller 81 and a pressure roller 82, so that the toner images transferred onto the sheet S are thermally fixed onto the sheet S.

[0059] The sheet S discharged from the fixing unit 80 is accumulated in a paper discharge tray 13 on the upper surface of the housing 10 by a conveying roller 15 and a discharge roller 16.

[0060] Here, with reference to FIG. 5, an outline of a mechanism for moving the developing roller 61, the agitator 67, the separating mechanism including the cam 150, the photosensitive drum 50, and the fixing unit 80 by each motor will be described. The image forming apparatus 1 includes a first motor 3D, a second motor 3P, a third motor 3F, and a drive transmission mechanism 100. The first motor 3D drives the developing roller 61, the agitator 67, the cam 150 which is a part of the separation mechanism, and the nip pressure adjustment mechanism 85 of the fixing device 80. The first motor 3D can rotate in a first direction and a second direction opposite to the first direction, and the rotation direction and rotation speed are controlled by the control unit 2. The first direction is the rotation direction when forming an image, and in this specification, the case where the first motor 3D rotates in the first direction is also referred to as "forward rotation". The second direction is an exceptional rotation direction when the developing roller 61 is moved to the separation position when the power is turned on or when the cover 11 is moved from the open position to the closed position, and in this specification, the case where the first motor 3D rotates in the second direction is also referred to as "reverse rotation". The second motor 3P is a motor that rotates the multiple photosensitive drums 50 and the conveyor belt 73 of the conveyor device 70, and also transmits a driving force to the supply mechanism 22. The third motor 3F is a motor for rotating the heating roller 81 of the fixing unit 80.

[0061] The drive transmission mechanism 100 has a first gear train 100A capable of transmitting the drive force of the first motor 3D to cams 150Y, 150M, and 150C, a second gear train 100K capable of transmitting the drive force of the first motor 3D to a K cam 150K, and a third gear train 100D capable of transmitting the drive force of the first motor 3D to the developing roller 61. The cams 150Y, 150M, and 150C are mechanically connected via gears, and are provided so as to be rotated simultaneously by the drive force of the first motor 3D being transmitted thereto.

[0062] The first gear train 100A has a YMC clutch 140A. The YMC clutch 140A is an electromagnetic clutch that switches between a transmission state in which the driving force of the first motor 3D is transmitted to the cams 150Y, 150M, and 150C and a disconnection state in which the driving force is not transmitted to the cams 150Y, 150M, and 150C. The second gear train 100K has a K clutch 140K. The K clutch 140K is an electromagnetic clutch that switches between a transmission state in which the driving force of the first motor 3D is transmitted to the K cam 150K and a disconnection state in which the driving force is not transmitted to the K cam 150K. Note that FIG. 5 shows the cam 150 in a schematic manner. In the following description, the clutches 140A and 140K may be referred to as ON when in a transmission state, and as OFF when in a disconnection state.

[0063] The third gear train 100D has a plurality of mechanical clutches 120 each provided corresponding to a respective one of the plurality of developing rollers 61. As will be described in detail later, the mechanical clutch 120 is configured to transmit the driving force from the first motor 3D to the developing roller 61 in the contact position and not to transmit the driving force from the first motor 3D to the developing roller 61 in the separated position.

[0064] Furthermore, the image forming apparatus 1 has a fourth gear train 200 capable of transmitting the driving force of the first motor 3D to the nip pressure adjustment cam 87. The fourth gear train 200 has a nip pressure adjustment clutch 220. The nip pressure adjustment clutch 220 is an electromagnetic clutch, and switches between a transmission state in which the driving force of the first motor 3D is transmitted to the nip pressure adjustment cam 87 and a disconnection state in which the driving force is not transmitted to the nip pressure adjustment cam 87. Note that the nip pressure adjustment clutch 220 is shown diagrammatically in FIG. 5.

[0065] 6(a) and (b), the cam 150 has a disk portion 151, a gear portion 150G, a first cam portion 152, a second cam portion 153, and a phase detection wall 154. The cam 150 is a member that moves the corresponding developing roller 61 between a contact position and a separated position by rotating.

[0066] The disk portion 151 has a substantially disk shape, and is supported by the housing 10 so as to be rotatable. The gear portion 150G is formed on the outer periphery of the disk portion 151. The first cam portion 152 is an end face cam for moving the developing roller 61, and protrudes in the rotation axis direction from a first surface 151A which is one surface of the disc portion 151. The first cam portion 152 has a shape extending in the circumferential direction centered on the rotation axis of the cam 150. The first cam portion 152 has a cam surface 152F on its end surface in the rotation axis direction. The cam surface 152F has a first holding surface F1, a second holding surface F2, a first guide surface F3, and a second guide surface F4. The first holding surface F1 holds the cam follower 170 in the standby position. The second holding surface F2 holds the cam follower 170 in the protruding position. The first guide surface F3 is a surface that connects the first holding surface F1 and the second holding surface F2 and is inclined with respect to the first holding surface F1. The second guide surface F4 is a surface that connects the second holding surface F2 and the first holding surface F1 and is inclined with respect to the first holding surface F1. 9 to 11, the dot hatching on the first cam portion 152 represents the second holding surface F2.

[0067] The second cam portion 153 cooperates with the lever 160 to operate the mechanical clutch 120 and switch between transmission and disconnection of the mechanical clutch 120. The second cam portion 153 is a plate cam that protrudes in the direction of the rotation axis from a second surface 151B, which is the other surface of the disc portion 151. The second cam portion 153 protrudes from one of the side surfaces of the disc portion 151 opposite to the side surface on which the first cam portion 152 is arranged. The second cam portion 153 extends in an arc shape when viewed from the direction of the rotation axis. The second cam portion 153 is formed integrally with the disc portion 151. Therefore, the second cam portion 153 rotates together with the first cam portion 152.

[0068] The phase detection wall 154 is a wall extending in a circumferential direction about the rotation axis of the cam 150 and blocking light emitted by a light emitting element of the separation sensor 4 (see FIG. 9(b)). The phase detection wall 154 protrudes in the axial direction from the first surface 151A of the disc portion 151 at a position closer to the rotation center than the first cam portion 152. In other words, the phase detection wall 154 protrudes from the same side surface of the disc portion 151 as the side surface on which the first cam portion 152 is disposed. The phase detection wall 154 is disposed on the inside of the inner peripheral surface 152S of the first cam portion 152. The phase detection wall 154 has a first slit 154A and a second slit 154B for indicating the phase of the rotation direction of the cam 150. The first slit 154A passes light emitted by a light emitting element of the separation sensor 4 when the developing roller 61 is in the separation position. The second slit 154B transmits light emitted by the light emitting element of the separation sensor 4 when the developing roller 61 is in the contact position. The second slit 154B has a different circumferential size from the first slit 154A. Specifically, the circumferential size of the second slit 154B is larger than the circumferential size of the first slit 154A.

[0069] The housing 10 is provided with distance sensors 4 corresponding to black and cyan. The separation sensor 4 is a phase sensor capable of detecting the phase of the cams 150C, 150K. The separation sensor 4 is composed of a photointerrupter having a light-emitting element and a light-receiving element. The separation sensor 4 outputs an ON signal to the control unit 2 when the first slit 154A or the second slit 154B is located between the light-emitting element and the light-receiving element and the light-receiving element receives the light emitted by the light-emitting element, and outputs an OFF signal to the control unit 2 when the phase detection wall 154 is located between the light-emitting element and the light-receiving element to block the light emitted by the light-emitting element and the light-receiving element does not receive the light.

[0070] The first slit 154A and the second slit 154B described above allow light emitted by the light-emitting element of the separation sensor 4 to pass when the developing roller 61 is in the separated position and when it is in the contact position, respectively. Therefore, the separation sensor 4 outputs an ON signal to the control unit 2 when each developing roller 61 is in the separated position and light emitted by the light-emitting element is received by the light-receiving element through the first slit 154A. In addition, the separation sensor 4 outputs an ON signal to the control unit 2 when each developing roller 61 is in the contact position and light emitted by the light-emitting element is received by the light-receiving element through the second slit 154B.

[0071] In this embodiment, for convenience, the case where the light receiving element of the distance sensor 4 receives light is called ON, and the case where it does not receive light is called OFF. It does not matter which voltage is higher when outputting an ON signal or when outputting an OFF signal.

[0072] Next, the configuration and function of the mechanical clutch 120 will be described. 7(a) and (b), the mechanical clutch 120 has a planetary gear mechanism. The mechanical clutch 120 is configured to be switchable between a transmission state in which the driving force from the first motor 3D is transmitted to the developing roller 61 and a disconnection state in which the driving force from the first motor 3D is not transmitted to the developing roller 61. Specifically, the mechanical clutch 120 is configured to include a sun gear 121, a ring gear 122, and a carrier 123, which are elements that can rotate around one axis, and a planetary gear 124 supported by the carrier 123.

[0073] Sun gear 121 has a disk portion 121B that rotates integrally with gear portion 121A, and a plurality of claw portions 121C provided on the outer periphery of disk portion 121B. Claw portions 121C have a pointed tip that is inclined circumferentially toward one rotational direction. The ring gear 122 has an inner gear 122A provided on its inner circumferential surface, and an input gear 122B provided on its outer circumferential surface.

[0074] The carrier 123 has four shaft portions 123A that rotatably support the planetary gear 124. In addition, the carrier 123 is provided with an output gear 123B on its outer circumferential surface.

[0075] The four planetary gears 124 are provided, and each is rotatably supported by a shaft portion 123A of the carrier 123. The planetary gears 124 mesh with a gear portion 121A of the sun gear 121 and also mesh with an inner gear 122A of the ring gear 122.

[0076] The mechanical clutch 120 has an input gear 122B that meshes with an idle gear (not shown) that rotates by receiving a driving force from the first motor 3D, and an output gear 123B that meshes with a coupling gear 117 shown in Figures 9(a) and (b). A coupling shaft 119 is coaxially connected to the coupling gear 117, so that when the coupling gear 117 rotates, the coupling shaft 119 rotates integrally therewith.

[0077] Returning to FIG. 7, the operation of mechanical clutch 120 will be described. When sun gear 121 is stopped from rotating, a transmission state is established in which the driving force input to input gear 122B can be transmitted to output gear 123B. On the other hand, when the sun gear 121 is in a rotatable state, the driving force input to the input gear 122B cannot be transmitted to the output gear 123B, and therefore the input gear 122B is in a disconnected state. When a driving force is input to the input gear 122B while the mechanical clutch 120 is in a disengaged state and a load is applied to the output gear 123B, the output gear 123B does not rotate and the sun gear 121 rotates idly.

[0078] 9(a), the drive transmission mechanism 100 further includes a lever 160 that swings while being guided by the second cam portion 153. The lever 160 is swingably supported by a support shaft 102A fixed to the housing 10. The levers 160 are provided corresponding to the colors yellow, magenta, cyan, and black. Lever 160 cooperates with cam 150 to engage with sun gear 121, which is one of the elements of the planetary gear mechanism, sun gear 121, ring gear 122, and carrier 123, to restrict the rotation of sun gear 121 and to place mechanical clutch 120 in a transmission state, and to disengage from sun gear 121 to place mechanical clutch 120 in a disconnected state. When cam 150 rotates forward, lever 160 switches mechanical clutch 120 between the transmission state and the disconnected state, and when cam 150 rotates reversely, lever 160 maintains mechanical clutch 120 in the disconnected state.

[0079] Specifically, as shown in FIG. 8( a ), the lever 160 has a first lever 161 , a second lever 162 , and a second spring 163 . The first lever 161 is capable of swinging around a swing axis X2 which is the central axis of the support shaft 102A, and is capable of coming into contact with the second cam portion 153. The first lever 161 has a rotation support portion 161A having a hole 161B which fits onto the support shaft 102A, a first arm 161C extending from the rotation support portion 161A, and a protrusion 161D protruding from the rotation support portion 161A on the side opposite to the first arm 161C.

[0080] The second lever 162 can swing around the swing axis X2. The second lever 162 can engage with the sun gear 121, which is one element of the mechanical clutch 120. The second lever 162 is combined with the first lever 161, and can swing around the swing axis X2 relative to the first lever 161 as well, as shown in Figs. 8(b) and (c). In other words, the first lever 161 is combined with the second lever 162 so as to be swingable around the swing axis X2 relative to the second lever 162. As shown in Fig. 8(c), the position where the first lever 161 swings with respect to the second lever 162 against the biasing force of the second spring 163 is referred to as the "swing position."

[0081] The second lever 162 has a rotation support part 162A having a hole 162B that fits onto the support shaft 102A, a second arm 162C extending from the rotation support part 162A, a rotation restriction part 162D, and a spring hook part 162E. The rotation restriction part 162D protrudes from the second arm 162C in the direction in which the oscillation axis X2 extends. As shown in FIG. 8(b), the rotation restriction part 162D restricts the rotation of the second lever 162 relative to the first lever 161 in one direction by contacting with a protrusion 161D.

[0082] The second spring 163 is a torsion spring, and biases the first lever 161 in a direction in which the protrusion 161D abuts against the rotation restricting portion 162D relative to the second lever 162. In other words, the second spring 163 biases the first lever 161 so as not to rotate relative to the second lever 162 when the rotation restricting portion 162D provided on the second lever 162 comes into contact with the protrusion 161D of the first lever 161.

[0083] In the lever 160, when the first lever 161 and the second lever 162 are combined, the tip of the second arm 162C extends toward the outer circumferential surface of the disk portion 121B of the sun gear 121. As shown in FIG. 9B, one end of a third spring 169 is hooked to the spring hook portion 162E. The third spring 169 is a tension spring, and the other end of the third spring 169 is hooked to a spring hook portion (not shown) of the housing 10. As a result, the third spring 169 biases the second lever 162 clockwise in FIG. 9B. That is, the third spring 169 biases the second arm 162C of the second lever 162 in a direction to swing toward the outer circumferential surface of the sun gear 121 (disk portion 121B), which is one element of the planetary gear mechanism. Second arm 162C is capable of restricting the rotation of sun gear 121 by engaging with claw portion 121C on the outer circumferential surface of sun gear 121.

[0084] The tip of the first arm 161C of the lever 160 can come into contact with the outer circumferential surface of the second cam portion 153. The lever 160 can be moved between a transmission position in which the tip of the first lever 161 is separated from the second cam portion 153 and the second lever 162 is engaged with the claw portion 121C of the mechanical clutch 120 to bring the mechanical clutch 120 into a transmission state as shown in Fig. 9(a) and (b), and a non-transmission position in which the tip of the first lever 161 is brought into contact with the second cam portion 153 and is pushed and moved as shown in Fig. 10(a) and (b), so that the tip of the second lever 162 is disengaged from the claw portion 121C of the sun gear 121, which is one element of the planetary gear mechanism, to bring the mechanical clutch 120 into a disconnected state.

[0085] 9(a) and (b), and the YMC clutch 140A and the K clutch 140K are ON, when the first motor 3D rotates in the first direction, the drive transmission mechanism 100 can transmit the drive force to the agitator 67, the developing roller 61, and the separation mechanism. At this time, the cam 150 rotates clockwise in FIG. 9(b).

[0086] When the lever 160 is in the transmission position as shown in Figures 9(a) and (b) and the YMC clutch 140A and the K clutch 140K are OFF, if the first motor 3D rotates in the first direction, the drive transmission mechanism 100 can transmit drive force to the agitator 67 and the developing roller 61, but does not transmit drive force to the separation mechanism.

[0087] 10(a) and (b), and the YMC clutch 140A and the K clutch 140K are ON, when the first motor 3D rotates in the first direction, the drive transmission mechanism 100 does not transmit drive force to the agitator 67 and the developing roller 61, but can transmit drive force to the separation mechanism. At this time, the cam 150 rotates clockwise in FIG. 10(b), and the sun gear 121 rotates counterclockwise. As the cam 150 rotates, the lever 160 moves from the non-transmitting position in FIG. 10(a) and (b) to the transmitting position in FIG. 11(b).

[0088] 10(a) and (b), and the YMC clutch 140A and the K clutch 140K are OFF, when the first motor 3D rotates in the first direction, the drive transmission mechanism 100 does not transmit drive force to the agitator 67, the developing roller 61, and the separation mechanism. At this time, the cam 150 stops, unlike in FIG. 10(b), and the sun gear 121 rotates counterclockwise in FIG. 10(b). This state is maintained until the YMC clutch 140A and the K clutch 140K are turned ON.

[0089] 11(a), when the first motor 3D rotates in the second direction and the first lever 161 is pressed by the second cam portion 153 with the second lever 162 in contact with the claw portion 121C of the sun gear 121, which is one element of the planetary gear mechanism, the first lever 161 swings relative to the second lever 162 against the biasing force of the second spring 163 and is positioned at the swing position. In this way, the first lever 161 can swing relative to the second lever 162, so that excessive force is not applied to the lever 160 when the first motor 3D is rotated in the second direction.

[0090] Also, when the first motor 3D rotates in the second direction and the tip of the second lever 162 is in contact with the claw portion 121C, the sun gear 121 rotates clockwise in the figure. At this time, the inclined surface of the claw portion 121C hits the tip of the second lever 162, so that the claw portion 121C pushes the second lever 162 away in the radial direction due to the rotation of the sun gear 121. Therefore, the sun gear 121 rotates clockwise while flicking the second lever 162. In this way, the second lever 162 does not stop the rotation of the sun gear 121, so the mechanical clutch 120 is in a disconnected state. In other words, when the first motor 3D rotates in the second direction, the mechanical clutch 120 is in a disconnected state, so that the developing roller 61 and the agitator 67 do not rotate.

[0091] In other words, when the YMC clutch 140A or the K clutch 140K is ON, when the first motor 3D rotates in the second direction, the drive transmission mechanism 100 does not transmit the drive force to the agitator 67 and the developing roller 61, but can transmit the drive force to the separation mechanism. In addition, in a state where the YMC clutch 140A and the K clutch 140K are OFF, when the first motor 3D rotates in the second direction, the drive transmission mechanism 100 does not transmit drive force to the agitator 67, the developing roller 61, and the separation mechanism.

[0092] Next, a control method performed by the control unit 2 will be described. The control unit 2 is a device that controls the overall operation of the image forming apparatus 1. The control unit 2 has a CPU, a ROM, a RAM, an input / output unit, etc., and executes each process by executing a program stored in advance.

[0093] In this embodiment, the control unit 2 controls the YMC clutch 140 A and the K clutch 140 K based on a signal from the separation sensor 4 , and controls the contact and separation of the developing roller 61 with respect to the photosensitive drum 50 .

[0094] When forming an image on the sheet S, the control unit 2 executes an image forming process by rotating the first motor 3D at a first speed and rotating the agitator 67 at a third speed. In addition, the control unit 2 rotates the photosensitive drum 50, the conveyor belt 73, the heating roller 81, and the pressure roller 82 in the image forming process.

[0095] Furthermore, when the power is turned ON or the cover 11 is moved from the open position to the closed position, the control unit 2 executes an initial separation process to rotate the first motor 3D at a first speed to position the developing rollers 61 of the multiple developing cartridges 60 at the separated positions, and then executes a determination process to determine whether or not the multiple developing cartridges 60 include a new developing cartridge 60. That is, the control unit 2 executes the initial separation process before the determination process.

[0096] In the initial separation process, the control unit 2 rotates the first motor 3D in the second direction. When performing the initial separation process, the control unit 2 rotates the first motor 3D while stopping the second motor 3P and the third motor 3F.

[0097] Furthermore, the control unit 2 executes the determination process by reading, from the memory 68, identification data indicating whether or not the developing cartridge 60 to which the memory 68 is attached is a new product.

[0098] If the result of the determination process indicates that a new developing cartridge 60 is included, the control unit 2 executes an initial agitation process in which the agitator 67 agitates the toner by rotating the first motor 3D at a second speed slower than the first speed. The control unit 2 executes the initial agitation process by rotating the first motor 3D in the first direction. In the initial agitation process, the control unit 2 rotates the agitator 67 at a fourth speed slower than the third speed without rotating the photosensitive drum 50 and the conveyor belt 73. The first speed is the maximum speed of the first motor 3D and is also called "full speed". The second speed is half the first speed and is also called "half speed". The second motor 3P and the third motor 3F are also called "full speed" when they rotate at their maximum speeds.

[0099] When performing the initial stirring process, the control unit 2 rotates the first motor 3D while stopping the second motor 3P and the third motor 3F.

[0100] On the other hand, the control unit 2 does not execute the initial mixing process if a new developing cartridge 60 is not included. If a new developing cartridge 60 is not included, the control unit 2 does not execute the initial mixing process, and executes the next process, for example, a cleaning process for the conveyor belt 73, initialization of the fixing unit 80, etc.

[0101] An example of a specific process of the control unit 2 that realizes the above-described control unit 2 will be described with reference to Figures 12 and 13. In the figures, the developing cartridge 60 is omitted and is referred to as "cartridge".

[0102] 12, when the control unit 2 determines that the power is turned on or the cover 11 is closed (S110, Yes), it executes the initial operation from step S120 onwards. When executing the initial operation, the control unit 2 rotates the first motor 3D in the second direction at the first speed and executes the initial separation process (S120). As a result, each developing roller 61 is located at the separation position.

[0103] After the initial separation process, the control unit 2 executes a memory reading process (S200). As shown in FIG. 13, in the memory reading process (S200), the control unit 2 first initializes a variable N indicating the cartridge ID to 1 and a variable F indicating the number of new developing cartridges 60 to 0 (S210).

[0104] Then, the control unit 2 reads the identification data from the memory 68 of the Nth developer cartridge 60 (S220), and determines whether the read identification data indicates a new product (S230). If the control unit 2 determines that the identification data indicates a new product (S230, Yes), it increments the variable F (S240) and rewrites the identification data in the memory 68 of the Nth developer cartridge 60 to data indicating an old product (S250).

[0105] After step S250, or if it is determined in step S230 that the identification data does not indicate a new product (No), the control unit 2 increments the variable N (S260). The control unit 2 determines whether the variable N is greater than 4 (whether memory reading of all cartridges has been completed) (S270), and if it is determined that the variable N is not greater (No), the control unit 2 returns to step S220 and repeats the process. On the other hand, if the control unit 2 determines that the variable N is greater than 4 (Yes), the control unit 2 ends the memory reading process (S200).

[0106] Returning to FIG. 12, after the memory reading process (S200), the control unit 2 judges whether the variable F is greater than 0 (whether there is an unused cartridge) (S140), and when it is judged that the variable F is greater than 0 (Yes), the control unit 2 rotates the first motor 3D in the first direction at the second speed to execute the initial stirring process (S150). After that, the control unit 2 rotates the first motor 3D, the second motor 3P, and the third motor 3F at full speed (the maximum speed of each motor), and executes cleaning of the conveyor belt 73 and initialization of the fixing unit 80 (S160). Then, the control unit 2 develops a patch pattern of a predetermined density and color on the conveyor belt 73, reads this patch pattern with a sensor (not shown), and executes correction of the developing bias, gamma correction, and color shift correction (S170), and ends the initial operation.

[0107] If the control unit 2 determines in step S140 that the variable F is not greater than 0 (No), it does not execute the initial stirring process (S150), but rotates the first motor 3D, the second motor 3P and the third motor 3F at full speed (the maximum speed of each motor), cleans the conveyor belt 73 and initializes the fixing unit 80 (S180), and ends the initial operation.

[0108] An example of the initial operation of the image forming apparatus 1 according to the above-mentioned process will be described with reference to Figures 14 and 15. Here, the operation related to the Y, M, and C developer cartridges 60 (YMC clutch 140A) will be described, but the same applies to the K developer cartridge 60.

[0109] FIG. 14 shows the initial operation when a new developer cartridge 60 is included in the multiple developer cartridges 60 that are installed. After the cover 11 is located at the closed position or after the power is turned on, the control unit 2 rotates the first motor 3D in the reverse direction at the first speed, simultaneously turns on the heater 81A of the fixing unit 80 to start preheating (t2), and turns on the YMC clutch 140A (t3). This causes the cam 150 to rotate in the reverse direction. During the reverse rotation of the cam 150, the second slit 154B is detected by the separation sensor 4, and a long ON signal is output (time t6 to t7). When the cam 150 further rotates in the reverse direction, as shown in FIG. 11(a), the contact portion 172 is located on the second holding surface F2, and the slide shaft portion 171 is located at the protruding position, so that the developing roller 61 is located at the separation position (t8). Then, the first slit 154A passes the separation sensor 4, and the signal of the separation sensor 4 turns ON (t9), and then turns OFF (t10). Then, the first lever 161 of the lever 160 comes into contact with the second cam portion 153. At this time, the second lever 162 cannot move because it remains in contact with the sun gear 121, and instead the first lever 161 swings against the biasing force of the second spring 163 to the swing position. Furthermore, when a predetermined time T1 has elapsed since the separation sensor 4 turned OFF (t10), the control unit 2 turns OFF the YMC clutch 140A (t11) and stops the first motor 3D (t12).

[0110] After that, the control unit 2 rotates the first motor 3D forward at the first speed (t13) and turns on the YMC clutch 140A (t14), thereby rotating the cam 150 forward a little. Then, the control unit 2 turns off the YMC clutch 140A when a predetermined time T2 has elapsed since the first slit 154A reaches the separation sensor 4 and the separation sensor 4 turns on after the cam 150 has rotated forward by a predetermined angle (t15). Then, the control unit 2 stops the first motor 3D (t16). At this time, as shown in FIG. 11(b), the contact portion 172 is located on the second holding surface F2, and the slide shaft portion 171 is located in the protruding position, so that the developing roller 61 is located in the separated position. Also, the lever 160 is in a state in which the second lever 162 engages with the claw portion 121C of the sun gear 121, and the tip portion of the first lever 161 is separated to the right from the second cam portion 153. This ends the initial separation process. In the initial separation process, after rotating the first motor 3D in reverse, the first motor 3D is rotated slightly in the forward direction to adjust the phase of the cam 150. However, since the amount of forward rotation here is very small and the sun gear 121 needs to rotate to a certain extent before the second lever 162 engages with the claw portion 121C of the sun gear 121, the forward rotation of the first motor 3D here causes the agitator 67 to not rotate at all or to rotate only slightly.

[0111] After the initial separation process, the control unit 2 turns off the heater 81A of the fixing unit 80 to interrupt preheating (t20), and rotates the first motor 3D forward at the second speed (t20 to t21) while keeping the YMC clutch 140A off to execute the initial mixing process. In the initial mixing process, the second motor 3P and the third motor 3F remain stopped. As a result, the agitator 67 rotates at a fourth speed that is slower than the third speed for image formation, and mixes the toner in the storage chamber. Since the first motor 3D rotates at the second speed, it is possible to rotate the agitator 67 with a large torque. Therefore, even if the toner in the new developer cartridge 60 is solidified, it can be loosened and mixed by the agitator 67.

[0112] After performing the initial stirring process for a predetermined time (e.g., 30 seconds), the control unit 2 turns on the heater 81A of the fixing unit 80 to resume preheating (t21), rotates the first motor 3D forward at the first speed (t30 to t31), and then rotates the first motor 3D in reverse at the first speed (t34 to t35), activates the nip pressure adjustment mechanism 85 of the fixing unit 80, and performs an operation of moving the pressure roller 82 away from the heating roller 81 and an operation of moving it closer to the heating roller 81 to return it to its original position. At time t30, the control unit 2 starts rotating the first motor 3D in the forward direction, and rotates the second motor 3P and the third motor 3F at full speed (t30 to t33). This cleans the conveyor belt 73, and rotates the heating roller 81 and the pressure roller 82 while the heater 81A of the fixing device 80 is ON. By rotating the heating roller 81 and the pressure roller 82 while the heater 81A of the fixing device 80 is ON, the temperatures of the surfaces of the heating roller 81 and the pressure roller 82 are made uniform. In addition, it is possible to remove any creases (nip marks) such as dents and wrinkles that have occurred in the pressure roller 82 due to the heating roller 81 and the pressure roller 82 being in contact with each other. After that, although not shown in the drawing, a correction process using a patch pattern is performed, and the initial operation is completed.

[0113] On the other hand, if the installed multiple developer cartridges 60 do not include a new developer cartridge 60, as shown in Fig. 15, after the initial separation process from time t2 to t16, the initial mixing process (t20 to t21 in Fig. 14) is not performed, and the fixation device 80 is initialized and the conveyor belt 73 is cleaned (t30 to t35). This makes it possible to quickly complete the initial operation without unnecessarily mixing the toner.

[0114] As described above, according to the image forming apparatus 1 of the present embodiment, when a new developer cartridge 60 is attached, the first motor 3D is rotated at the second speed slower than that during image formation, and the agitator 67 is rotated at the fourth speed slower than that during image formation to execute the initial stirring process, so that the torque of the first motor 3D can be increased, and even if the toner is solidified, the toner can be easily loosened. Also, when only a developer cartridge 60 that is not new is attached, the initial stirring process is not executed, so that unnecessary stirring of the toner is suppressed. This makes it possible to suppress the deterioration of toner and to prevent unnecessary power consumption.

[0115] Then, the control unit 2 reads out the identification data from the memory 68 and performs the determination process, so that there is no need to operate the first motor 3D in the determination process, and unnecessary agitation of the toner is suppressed.

[0116] In addition, since the control unit 2 executes the initial stirring process with the developing roller 61 in the separated position, the load on the first motor 3D in the initial stirring process can be reduced. Also, since the determination process is executed with the developing roller 61 in the separated position, even if the user has not correctly attached the developing cartridge 60, the action of moving the developing cartridge 60 to the separated position can correctly attach the developing cartridge 60, ensuring a connection between the contacts of the memory 68 and the contacts of the drawer 90, and making it easier to correctly read the identification data from the memory 68.

[0117] Furthermore, since the control unit 2 does not rotate the agitator 67 and the developing roller 61 in the initial separation process, the load on the first motor 3D in the initial separation process is reduced, and deterioration of the toner and the developing roller 61 can be suppressed.

[0118] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be appropriately modified and carried out.

[0119] For example, in the above embodiment, in the initial separation process, the first motor 3D is rotated in the second direction, but depending on the structure of the drive transmission mechanism, etc., it may be rotated in the first direction. Also, the initial stirring process may be executed without executing the initial separation process.

[0120] In addition, in the above embodiment, the fixing device 80 is initialized after the initial mixing process is completed, but if the nip pressure adjustment mechanism 85 of the fixing device 80 is driven by a motor other than the first motor 3D, the fixing device 80 may be initialized simultaneously with the initial mixing process. Cleaning of the conveyor belt 73 may also be performed simultaneously with the initial mixing process.

[0121] In addition, in the above embodiment, as shown in Figures 14 and 15, in the initial separation process, the first motor 3D is rotated in reverse at the first speed (t2-t12) and then rotated in forward direction at the first speed (t13-t16). However, as shown in Figures 16 and 17, the first motor 3D may be rotated in reverse at the first speed (t2-t12) and then rotated in forward direction at the second speed (t13-t16).

[0122] In addition, in the above embodiment, as shown in Figures 14 and 15, after performing the initial stirring process, when the nip pressure adjustment mechanism 85 of the fixing device 80 is operated to move the pressure roller 82 away from the heating roller 81 and then move it closer to the original position, the first motor 3D is rotated forward at a first speed (t30 to t31) and then rotated reversely at the first speed (t34 to t35), but as shown in Figures 16 and 17, the first motor 3D may be rotated forward at a second speed (t30 to t31) and then rotated reversely at the second speed (t34 to t35) to operate the nip pressure adjustment mechanism 85 of the fixing device 80.

[0123] In the above embodiment, the conveyor belt 73 is shown as an example of a belt, but the belt may be an intermediate transfer belt.

[0124] In the above embodiment, the developing cartridge 60 is shown as an example of a cartridge, but the cartridge may be a process cartridge having a photosensitive drum.

[0125] In the above embodiment, the heating roller 81 is shown as an example of a rotating body, but the rotating body may be an endless belt.

[0126] In addition, in the above embodiment, an image forming apparatus 1 that prints color images using four color toners is exemplified, but the image forming apparatus may also be an apparatus that prints color images using three or five color toners.

[0127] The image forming apparatus may also be a multifunction machine or a copier.

[0128] Furthermore, the elements described in the above embodiment and modified examples can be implemented in appropriate combinations. [Explanation of symbols]

[0129] 1. Image forming device 2. Control section 3D 1st motor 3P 2nd motor 3F 3rd motor 10. Chassis 10A aperture 11 Cover 50 Photosensitive drum 60 Developer Cartridge 61 Developing roller 67 Agitator 68 Memory 73 Conveyor Belt 100 Drive transmission mechanism

Claims

1. A housing having an opening; A photosensitive drum; a cover movable between a closing position for closing the opening and an opening position for opening the opening; a plurality of cartridges each having a developing roller, a chamber for containing toner, and an agitator for agitating the toner, the cartridges being attached to the housing through the opening; A first motor that rotates the agitator; a separation mechanism that can move the developing roller between a contact position where the developing roller contacts the photosensitive drum and a separation position where the developing roller is separated from the photosensitive drum; a drive transmission mechanism that transmits a drive force of the first motor to the separation mechanism; A control unit and an image forming apparatus comprising: The developing roller is driven by the first motor, the drive transmission mechanism is configured to transmit a drive force to the agitator, the developing roller, and the spacing mechanism when the first motor rotates in a first direction, and to transmit the drive force to the spacing mechanism without transmitting the drive force to the agitator and the developing roller when the first motor rotates in a second direction opposite to the first direction; The control unit is When forming an image on a sheet, rotating the first motor at a first speed to rotate the agitator; When the power is turned on or when the cover is moved from the open position to the closed position, executing a determination process for determining whether or not the plurality of cartridges includes a new cartridge; If the cartridge is a new cartridge, an initial agitation process is performed in which the first motor is rotated at a second speed slower than the first speed to agitate the toner with the agitator; If a new cartridge is not included, the initial stirring process is not performed by rotating the first motor at the second speed, an initial separation process is performed to position the developing rollers of the cartridges at a separation position before the determination process is performed; The image forming apparatus according to claim 1, wherein the first motor is rotated in the second direction in the initial separation process.

2. A housing having an opening; A photosensitive drum; a cover movable between a closing position for closing the opening and an opening position for opening the opening; a plurality of cartridges each having a developing roller, a chamber for containing toner, and an agitator for agitating the toner, the cartridges being attached to the housing through the opening; A first motor that rotates the agitator; A second motor that rotates the photosensitive drum; A control unit and an image forming apparatus comprising: The control unit is When forming an image on a sheet, rotating the first motor at a first speed to rotate the agitator; When the power is turned on or when the cover is moved from the open position to the closed position, executing a determination process for determining whether or not the plurality of cartridges includes a new cartridge; If the cartridge is a new cartridge, an initial agitation process is performed in which the first motor is rotated at a second speed slower than the first speed to agitate the toner with the agitator; If a new cartridge is not included, the initial stirring process is not performed by rotating the first motor at the second speed, an image forming apparatus including: a step of rotating the first motor while the second motor is stopped, and executing the initial stirring process;

3. A housing having an opening; A photosensitive drum; a cover movable between a closing position for closing the opening and an opening position for opening the opening; a plurality of cartridges each having a developing roller, a chamber for containing toner, and an agitator for agitating the toner, the cartridges being attached to the housing through the opening; A first motor that rotates the agitator; a fixing unit having a rotating body for fixing a toner image formed on a sheet; A third motor that rotates the rotating body; A control unit and an image forming apparatus comprising: The control unit is When forming an image on a sheet, rotating the first motor at a first speed to rotate the agitator; When the power is turned on or when the cover is moved from the open position to the closed position, executing a determination process for determining whether or not the plurality of cartridges includes a new cartridge; If the cartridge is a new cartridge, an initial agitation process is performed in which the first motor is rotated at a second speed slower than the first speed to agitate the toner with the agitator; If a new cartridge is not included, the initial stirring process is not performed by rotating the first motor at the second speed, an image forming apparatus including: a step of rotating the first motor while the third motor is stopped, and executing the initial stirring process;

4. each of the cartridges has a memory in which identification data indicating whether the cartridge is new or not is recorded; 4. The image forming apparatus according to claim 1, wherein the control unit executes the determination process by reading the identification data from the memory.

5. A belt disposed opposite the photosensitive drum; a fixing unit having a rotating body for fixing a toner image formed on a sheet; a second motor that rotates the photosensitive drum and the belt; A third motor that rotates the rotating body, The control unit is 2 . The image forming apparatus according to claim 1 , wherein the first motor is rotated in a state where the second motor and the third motor are stopped, and the initial stirring process is performed.

6. The image forming apparatus according to claim 5 , wherein the control unit executes the initial separation process by rotating the first motor while keeping the second motor and the third motor stopped.

7. A housing having an opening; A photosensitive drum; a cover movable between a closing position for closing the opening and an opening position for opening the opening; a plurality of cartridges each having a developing roller, a chamber for containing toner, and an agitator for agitating the toner, the cartridges being attached to the housing through the opening; A belt disposed opposite the photosensitive drum; A control method for an image forming apparatus including a fixing unit having a rotating body that fixes a toner image formed on a sheet, the control method comprising: rotating the agitator at a third speed when forming an image on the sheet; When the power is turned on or when the cover is moved from the open position to the closed position, executing a determination process for determining whether or not the plurality of cartridges includes a new cartridge; If the cartridge is a new cartridge, an initial agitation process is performed to rotate the agitator at a fourth speed that is slower than the third speed to agitate the toner; If a new cartridge is not included, the initial stirring process is not performed by rotating the agitator at the fourth speed, When forming an image on a sheet, the photosensitive drum, the belt and the agitator are rotated; a control method for an image forming apparatus, comprising: rotating the agitator without rotating the photosensitive drum and the belt when the initial agitation process is performed;

8. A housing having an opening; A photosensitive drum; a cover movable between a closing position for closing the opening and an opening position for opening the opening; a plurality of cartridges each having a developing roller, a chamber for containing toner, and an agitator for agitating the toner, the cartridges being attached to the housing through the opening; A first motor that rotates the agitator; a separation mechanism that can move the developing roller between a contact position where the developing roller contacts the photosensitive drum and a separation position where the developing roller is separated from the photosensitive drum; A control unit and an image forming apparatus comprising: the agitator is switchable between a state in which the agitator rotates when a driving force from the first motor is transmitted thereto via a clutch and a state in which the agitator does not rotate when a driving force from the first motor is not transmitted thereto, The control unit is When forming an image on a sheet, rotating the first motor at a first speed to rotate the agitator; When the power is turned on or when the cover is moved from the open position to the closed position, performing an initial separation process in which the first motor is rotated and the agitator is not rotated to position the developing rollers of the plurality of cartridges at the separation positions; After the initial separation process is performed, a determination process is performed to determine whether or not the plurality of cartridges includes a new cartridge; As a result of the determination process, If the cartridge is a new cartridge, an initial agitation process is performed in which the first motor is rotated at a second speed slower than the first speed, and the agitator is rotated to agitate the toner with the agitator; an image forming apparatus, characterized in that, if a new cartridge is not included, the image forming apparatus does not perform the initial stirring process by rotating the first motor at the second speed and rotating the agitator.

9. each of the cartridges has a memory in which identification data indicating whether the cartridge is new or not is recorded; 9. The image forming apparatus according to claim 8, wherein the control unit executes the determination process by reading the identification data from the memory.

10. a drive transmission mechanism that transmits a drive force of the first motor to the separation mechanism, The developing roller is driven by the first motor, the drive transmission mechanism is configured to transmit a drive force to the agitator, the developing roller, and the spacing mechanism when the first motor rotates in a first direction, and to transmit the drive force to the spacing mechanism without transmitting the drive force to the agitator and the developing roller when the first motor rotates in a second direction opposite to the first direction; The control unit is 10. The image forming apparatus according to claim 8, wherein in the initial separation process, the first motor is rotated in the second direction.

11. A second motor that rotates the photosensitive drum is further provided, The control unit is 11. The image forming apparatus according to claim 8, wherein the first motor is rotated in a state where the second motor is stopped, and the initial stirring process is performed.

12. a fixing unit having a rotating body for fixing a toner image formed on a sheet; A third motor that rotates the rotating body is further provided. The control unit is 11. The image forming apparatus according to claim 8, wherein the first motor is rotated in a state where the third motor is stopped, and the initial stirring process is performed.

13. A housing having an opening; A photosensitive drum; a cover movable between a closing position for closing the opening and an opening position for opening the opening; a plurality of cartridges each having a developing roller, a chamber for containing toner, and an agitator for agitating the toner, the cartridges being attached to the housing through the opening; A first motor that rotates the agitator; A belt disposed opposite the photosensitive drum; a fixing unit having a rotating body for fixing a toner image formed on a sheet; a second motor that rotates the photosensitive drum and the belt; A third motor that rotates the rotating body; a separation mechanism that can move the developing roller between a contact position where the developing roller contacts the photosensitive drum and a separation position where the developing roller is separated from the photosensitive drum; A control unit and an image forming apparatus comprising: The control unit is When forming an image on a sheet, rotating the first motor at a first speed to rotate the agitator; When the power is turned on or when the cover is moved from the open position to the closed position, performing an initial separation process in which the first motor is rotated to position the developing rollers of the plurality of cartridges at the separation position; After the initial separation process is performed, a determination process is performed to determine whether or not the plurality of cartridges includes a new cartridge; If the cartridge is a new cartridge, an initial agitation process is performed in which the first motor is rotated at a second speed slower than the first speed to agitate the toner with the agitator; If a new cartridge is not included, the initial stirring process is not performed by rotating the first motor at the second speed, an image forming apparatus including: a step of rotating the first motor while the second motor and the third motor are stopped, and performing the initial stirring process;

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