Image forming apparatus

This application claims priority under 35 U.S.C. § 119 from Japanese Patent Application No. 2020-120827 filed on Jul. 14, 2020. The entire subject matter of the application is incorporated herein by reference.

The present disclosures relate to an image forming apparatus.

Conventionally, there has been known an image forming apparatus having a housing with an opening, a cover, an interlocking mechanism, a sensor, and a controller. The cover is generally configured to move between a closed position at which the cover covers the opening and an open position at which the cover uncovers the opening. The interlocking mechanism typically includes a cam that interlocks with the cover. The cam is configured to move a developing roller away from a photosensitive drum.

According to a conventional configuration, there is known a configuration in which the controller moves the cam after the image forming apparatus is powered on and determines whether the cover was opened or closed during the image forming apparatus was powered off based on a time until the sensor detects the cam.

In the above-mentioned conventional configuration, the controller is typically configured to move the cam every time when the image forming apparatus is powered on in order to determine whether the cover was opened or closed while the image forming apparatus was powered off.

In such a configuration, even if the developing roller is in a state of being separated from the photosensitive drum at a time when the image forming apparatus is powered on, the developing roller is once brought into contact with the photosensitive drum and then separated from the drum.

Such a configuration causes the developing roller to come into contact with the photosensitive drum even when the developing roller does not need to contact the photosensitive drum.

According to aspects of the present disclosures, there is provided an image forming apparatus including a housing formed with an opening, a cover configured to be movable between a closed position at which the cover closes the opening and an open position at which the cover uncovers the opening, a photosensitive drum, a developing roller movable between a contact position at which the developing roller contacts the photosensitive drum and a separation position at which the developing roller is spaced from the photosensitive drum, a separation mechanism configured to move the developing roller from the contact position to the separation position, the separation mechanism allowing movement of the developing roller from the separation position to the contact position in association with a movement of the cover from the closed position to the open position, a controller configured to control the separation mechanism to move the developing roller between the separation position and the contact position, an interlocking mechanism configured to change a state from a first state to a second state in association with movement of the cover from the closed position to the open position in a case where the cover moves from the closed position to the open position while no power is supplied is to the controller, and a sensor configured to detect whether the interlocking mechanism is in the second state. The separation mechanism is configured to in a case where the sensor does not detect that the interlocking mechanism is in the second state when power supply to the controller is started, keep the developing roller located at the separation position at the separation position, and in a case where the sensor detects that the interlocking mechanism is in the second state when power supply to the controller is started, move the developing roller located at the contact position to the separation position.

According to aspects of the present disclosures, there is provided an image forming apparatus, including a housing formed with an opening, a cover configured to be movable between a closed position at which the cover closes the opening and an open position at which the cover uncovers the opening, a photosensitive drum, a developing roller movable between a contact position at which the developing roller contacts the photosensitive drum and a separation position at which the developing roller is spaced from the photosensitive drum, a separation mechanism configured to move the developing roller from the contact position to the separation position, the separation mechanism allowing movement of the developing roller from the separation position to the contact position in association with a movement of the cover from the closed position to the open position, a controller configured to control the separation mechanism to move the developing roller between the separation position and the contact position, an interlocking mechanism configured to change a state from a first state to a second state in association with movement of the cover from the closed position to the open position in a case where the cover moves from the closed position to the open position while no power is supplied is to the controller, and a sensor configured to detect whether the interlocking mechanism is in the second state. The separation mechanism is configured to in a case where the sensor does not detect that the interlocking mechanism is in the second state when power supply to the controller is started, perform a first warm-up process of causing the separation mechanism to keep the developing roller located at the separation position at the separation position, and, in a case where the sensor detects that the interlocking mechanism is in the second state when power supply to the controller is started, perform a second warm-up process of causing the separation mechanism to move the developing roller located at the contact position to the separation position.

FIG. 1 shows a schematic configuration of an image forming apparatus according to an embodiment of the present disclosure.

FIG. 2 schematically shows the image forming apparatus shown in FIG. 1 , with a cover being located at an open position and a drum unit being located at an outer position.

FIG. 3 schematically shows the image forming apparatus shown in FIG. 1 , with developing rollers being in separation positions.

FIG. 4 is a block diagram illustrating a control of the image forming apparatus.

FIG. 5A shows an interlocking mechanism shown in FIG. 4 , in a state where the cover is located at the closed position and the interlocking mechanism is in a first state.

FIG. 5B shows the interlocking mechanism shown in FIG. 5A , in a state where a contact member is separated from a lever of a sensor.

FIG. 6A shows the interlocking mechanism shown in FIG. 5A , in a state where the cover is located at the open position and the interlocking mechanism is in a second state.

FIG. 6B shows the interlocking mechanism shown in FIG. 6A , in a state where the contact member is pressing the lever of the sensor.

FIG. 7 shows the interlocking mechanism shown in FIG. 5A , in a state where the interlocking mechanism is in a second state and the cover is located at the closed position.

FIG. 8 is a perspective view of a sector gear of the interlocking mechanism shown in FIG. 5A .

FIG. 9A is a plan view of a first surface of the sector gear shown in FIG. 8 .

FIG. 9B is a plan view of a second surface of the sector gear shown in FIG. 8 .

FIG. 10 is a perspective view of a stopper employed in the interlocking mechanism shown in FIG. 5A .

FIG. 11 shows a positional relationship between the stopper shown in FIG. 10 and the sector gear shown in FIG. 5A .

FIG. 12A shows the separation mechanism shown in FIG. 4 , in a state where the cover is located at the closed position and the cam follower is located at a first rotational position.

FIG. 12B shows the separation mechanism shown in FIG. 12A , in a state where the cover is located at the open position and the cam follower is located at a second rotational position.

FIG. 13A shows the separation mechanism shown in FIG. 12A , in a state where the cam follower located at the first rotational position is located at a pressing position, and a developer cartridge is located at a position where the developing roller is separated from the photosensitive drum.

FIG. 13B shows the separation mechanism shown in FIG. 12A , in a state where the cam follower located at the first rotational position is located in a pressure release position and the developer cartridge is located at a position where the developing roller is in contact with the photosensitive drum.

FIG. 14A is a perspective view of the separation mechanism shown in FIG. 12A .

FIG. 14B is a perspective view of the separation mechanism shown in FIG. 12B .

FIG. 15 is a flowchart illustrating a control of the image forming apparatus.

FIG. 16 is a flowchart illustrating, in association with the flowchart shown in FIG. 15 , the control of the image forming apparatus.

1. Overview of Image Forming Apparatus 1

Referring to FIGS. 1 through 3 , an overview of an image forming apparatus 1 will be described.

As shown in FIG. 1 , the image forming apparatus 1 is equipped with a housing 2 , a cover 3 , a sheet container 4 , a drum unit 5 , an exposure device 6 , a plurality of developer cartridges 7 Y, 7 M, 7 C, 7 K, a transfer device 8 , and a fusing device 9 .

In the following description, suffixes “Y,” “M,” “C” and “K” will be added to reference numerals to indicate that components are for colors of yellow, magenta, cyan and black, respectively. For example, the developer cartridge 7 Y is the developer cartridge for yellow toner (i.e., accommodating yellow toner), the developer cartridge 7 M is for magenta toner, the developer cartridge 7 C is for cyan toner, and the developer cartridge 7 K is for black toner. It is noted that the order of the “Y,” “M,” “C” and “K” according to the present embodiment is only an example, and a different order can be employed arbitrarily. Further, the colors of yellow, magenta, cyan and black are examples, and different colors may be used.

1.1 Housing 2

The housing 2 houses the sheet container 4 , the drum unit 5 , the exposure device 6 , the plurality of developer cartridges 7 Y, 7 M, 7 C and 7 K, the transfer device 8 , and the fixing device 9 . The housing 2 has an opening 21 .

1.2 Cover 3

The cover 3 is configured to move between a closed position (see FIG. 1 ) and an open position (see FIG. 2 ). When the cover 3 is located at the closed position, the cover 3 closes the opening 21 . When the cover 3 is located at the open position, the cover 3 uncovers the opening 21 , which is exposed to the outside.

1.3 Sheet Container 4

The sheet container 4 is configured to accommodate a plurality of sheets S. The sheets S in the sheet container 4 are fed toward a photosensitive drum 51 Y, one by one. The sheet S is, for example, a printing sheet. The sheet container 4 may be a sheet cassette.

1.4 Drum Unit 5

As shown in FIG. 2 , in a state where the cover 3 is located at the open position, the drum unit 5 can be moved, in a first direction, between an inner position (see FIG. 1 ) and an outer position (see FIG. 2 ) through the opening 21 . When the drum unit 5 is located at the inner position, the drum unit 5 is located inside the housing 2 . When the drum unit 5 is located at the outer position, the drum unit 5 is located outside the housing 2 .

As shown in FIG. 1 , the drum unit 5 has a plurality of photosensitive drums 51 Y, 51 M, 51 C and 51 K, and a plurality of chargers 52 Y, 52 M, 52 C and 52 K. In other words, the image forming apparatus 1 has the photosensitive drums 51 Y.

1.4.1 Photosensitive Drums 51 Y, 51 M, 51 C and 51 K

The photosensitive drums 51 Y, 51 M, 51 C and 51 K are arranged in the first direction. Each of the photosensitive drums 51 M, 51 C and 51 K has the same structure as the photosensitive drum 51 Y. For this reason, the photosensitive drum 51 Y will be described in the following description, and descriptions on the photosensitive drums 51 M, 51 C, and 51 K will be omitted.

The photosensitive drum 51 Y extends in a second direction intersecting with the first direction. Preferably, the second direction is orthogonal to the first direction. The photosensitive drum 51 Y is rotatable about a drum axis A 1 that extends in the second direction.

1.4.2 Chargers 52 Y, 52 M, 52 C and 52 K

The charger 52 Y is configured to charge a surface of the photoreceptor drum 51 Y. The charger 52 M is configured to charge a surface of the photosensitive drum 51 M. The charger 52 C is configured to charge a surface of the photosensitive drum 51 C. The charger 52 K is configured to charge a surface of the photosensitive drum 51 K.

1.5 Exposure Device 6

In a state where the drum unit 5 is positioned at the inner position, the exposure device 6 exposes the photosensitive drum 51 Y, which has been charged by the charger 52 Y. According to the present embodiment, the exposure device 6 includes a laser scanning device. The exposure device 6 is configured to expose not only the photosensitive drum 51 Y but also the photosensitive drums 51 M, 51 C, and 51 K. The exposure device 6 may be an exposure head having an LED array.

1.6 Developer Cartridges 7 Y, 7 M, 7 C and 7 K

As shown in FIG. 2 , in a state where the cover 3 is located at the open position and the drum unit 5 is located at the outer position, the developer cartridges 7 Y, 7 M, 7 C and 7 K are attachable to the drum unit 5 .

As shown in FIG. 1 , when the developer cartridges 7 Y, 7 M, 7 C and 7 K are attached to the drum unit 5 and the drum unit 5 is located at the inner position, the developer cartridges 7 Y, 7 M, 7 C and 7 K may be attached inside the housing 2 . In a state where the cover 3 is located at the open position, the developer cartridges 7 Y, 7 M, 7 C and 7 K may be attached inside the housing 2 through the opening 21 .

Each of the developer cartridges 7 M, 7 C and 7 K has the same structure as the developer cartridge 7 Y. Therefore, the description of the developer cartridge 7 Y will be given and the description of the developer cartridges 7 M, 7 C and 7 K will be omitted.

The developer cartridge 7 Y is configured to contain toner. The developer cartridge 7 Y has a developing roller 71 Y. In other words, the image forming apparatus 1 has a developing roller 71 Y. The developing cartridges 7 M, 7 C and 7 K have respective developer rollers 71 M, 71 C and 71 K, similar to those described in connection with the developer cartridge 7 Y.

The developing roller 71 Y extends in the second direction. The developing roller 71 Y is rotatable about a developing axis A 2 . The developing axis A 2 extends in the second direction.

As shown in FIGS. 1 and 3 , in a state where the developer cartridge 7 Y is attached to the drum unit 5 and the drum unit 5 is located at the inner position, the developer cartridge 7 Y is movable between a position where the developing roller 71 Y contacts the photosensitive drum 51 Y (see FIG. 1 ) and a position where the developing roller 71 Y is spaced from the photosensitive drum 51 Y (see FIG. 3 ). In other words, the developing roller 71 Y can move between a contact position (see FIG. 1 ) and a separation position (see FIG. 3 ). In a state where the developing roller 71 Y is located at the contact position, the developing roller 71 Y is in contact with the photosensitive drum 51 Y. In a state where the developing roller 71 Y is located at the separation position, the developing roller 71 Y is spaced from the photosensitive drum 51 Y.

As shown in FIG. 1 , in a state where the developing roller 71 Y is located at the contact position, the developing roller 71 Y is capable of supplying toner accommodated in the developer cartridge 7 Y to the photosensitive drum 51 Y.

1.7 Transfer Device 8

The transfer device 8 has a belt 81 and a plurality of transfer rollers 82 Y, 82 M, 82 C and 82 K.

In a state where the drum unit 5 is located at the inner position, the belt 81 is in contact with the photosensitive drums 51 Y, 51 M, 51 C and 51 K. The belt 81 is configured to convey the sheet S fed from the sheet container 4 toward the fixing unit 9 .

The transfer roller 82 Y is configured to transfer the toner on the photosensitive drum 51 Y to the sheet S which is being conveyed by the belt 81 . In other words, the transfer device 8 transfers the toner on the photoreceptor drum 51 Y to the sheet S. Similarly, the transfer roller 82 M transfers the toner on the photosensitive drum 51 M to the sheet S being conveyed by the belt 81 . The transfer roller 82 C transfers the toner on the photoreceptor drum 51 C to the sheet S being conveyed by the belt 81 . The transfer roller 82 K transfers the toner on the photoreceptor drum 51 K to the sheet S being conveyed by the belt 81 .

1.8 Fixing Device 9

The fixing device 9 is configured to apply heat and pressure to the sheet S on which the toner has been transferred by the transfer rollers 82 Y, 82 M, 82 C and 82 K to fix the toner on the sheet S. The sheet S that has passed through the fixing device 9 is discharged on an upper surface of the housing 2 .

2. Details of the Image Forming Apparatus 1

Referring to FIG. 1 and FIGS. 3 through 14B , the details of the image forming apparatus 1 will be described.

As shown in FIGS. 1 and 4 , the image forming apparatus 1 is equipped with a power switch 11 (see FIG. 1 ), the interlocking mechanism 12 (see FIG. 4 ), the sensor 13 (see FIG. 4 ), the separation mechanism 14 (see FIG. 4 ), a plurality of drum cleaners 15 Y, 15 M, 15 C and 15 K (see FIG. 1 ), a belt cleaner 16 (see FIG. 1 ), and a controller 17 (see FIG. 4 ).

2.1 Power Switch 11

As shown in FIG. 1 , the power switch 11 is arranged on an outer surface of the housing 2 . The power switch 11 can be switched between an on state and an off state. In a state where the power switch 11 is in the on state, power to the controller 17 . In a state where the power switch 11 is in the off state, the power supply to the controller 17 is stopped.

2.2 Interlocking Mechanism 12

As shown in FIGS. 5A and 6A , the state of the interlocking mechanism 12 switches from the first state (see FIG. 5A ) to the second state (see FIG. 6A ) in conjunction with the movement of the cover 3 from the closed position (see FIG. 5A ) to the open position (see FIG. 6A ). That is, in a case where the cover 3 moves from the closed position to the open position while the power is not supplied to the controller 17 , the interlocking mechanism 12 switches from the first state to the second state in conjunction with the movement of the cover 3 from the closed position to the open position.

On the other hand, as shown in FIG. 6A and FIG. 7 , the interlocking mechanism 12 is not associated with the movement of the cover 3 from the open position to the closed position, but remains in the second state.

In detail, as shown in FIGS. 5A and 5B , the interlocking mechanism 12 has a drive gear 121 , a sector gear 122 , a protrusion 123 , a protrusion 124 , a contact member 125 (see FIG. 5B ), a spring 126 and a stopper 127 .

2.2.1 Drive Gear 121

The drive gear 121 is configured to be rotatable by receiving power from a motor not shown in the drawings.

2.2.2 Sector Gear 122

The sector gear 122 is rotatable about the axis A 11 between a sector first position (see FIG. 5A ) and a sector second position (see FIG. 6A ). According to the present embodiment, the axis A 11 extends in the second direction. As shown in FIG. 5A , in a state where the sector gear 122 is located at the sector first position, the sector gear 122 does not mesh with the drive gear 121 . On the other hand, as shown in FIG. 6A , in a state where the sector gear 122 is located at the sector second position, the sector gear 122 meshes with the drive gear 121 . The sector gear 122 meshes with the drive gear 121 at a position between the sector second position (see FIG. 6A ) and the sector first position (see FIG. 5A ). Then, the sector gear 122 moves from the sector second position to the sector first position by the power from the drive gear 121 .

As shown in FIG. 8 , the sector gear 122 has one surface S 100 and another surface S 200 arranged in a direction in which the axis A 11 extends. The sector gear 122 is supported by a particular shaft in the housing 2 . The shaft extends along the axis A 11 .

2.2.3 Protrusion 123

As shown in FIGS. 8 and 9A , the protrusion 123 is arranged on the one surface S 100 of the sector gear 122 . The protrusion 123 extends from the one surface S 100 of the sector gear 122 . The protrusion 123 may be attached to the one surface S 100 of the sector gear 122 . The protrusion 123 extends in the direction in which the axis A 11 extends. The protrusion 123 is located at a position spaced from the axis A 11 in the radial direction of the sector gear 122 .

2.2.4 Projection 124

The protrusion 124 is arranged on the one surface S 100 of the sector gear 122 . The protrusion 124 extends from the one surface S 100 of the sector gear 122 . The protrusion 124 may be attached to the one surface S 100 of the sector gear 122 . The protrusion 124 extends in the direction in which the axis A 11 extends. The protrusion 124 is arranged at a position spaced from the axis A 11 in the radial direction of the sector gear 122 . The protrusion 124 is arranged spaced from the protrusion 123 .

2.2.5 Contact Member 125

As shown in FIGS. 5B and 6B , the contact member 125 is configured to be movable, together with the sector gear 122 , between the first position (see FIG. 5B ) and the second position (see FIG. 6B ).

As shown in FIG. 5B , in a state where the sector gear 122 is located at the sector first position, the contact member 125 is located at the first position. In a state where the contact member 125 is located at the first position, the contact member 125 is located at a position space from the lever 13 A of the sensor 13 . In a case where the contact member 125 is located at the first position, the interlocking mechanism 12 is in the first state.

As shown in FIG. 6B , in a state where the sector gear 122 is located at the sector second position, the contact member 125 is located at the second position. In a state where the contact member 125 is located at the second position, the contact member 125 comes into contact with the lever 13 A of the sensor 13 . In a case where the contact member 125 is located at the second position, the interlocking mechanism 12 is in the second state.

As shown in FIGS. 8 and 9B , the contact member 125 is located on the other surface S 200 of the sector gear 122 . The contact member 125 extends from the other surface S 200 of the sector gear 122 . The contact member 125 may be attached to the other surface S 200 of the sector gear 122 . The contact member 125 extends in the direction in which the shaft A 11 extends. In the present embodiment, the contact member 125 is a cam. The contact member 125 is rotatable about the axis A 11 between the first position (see FIG. 5B ) and the second position (see FIG. 6B ). The contact member 125 has a cam surface 125 A. The cam surface 125 A is arranged spaced from the axis A 11 . As shown in FIG. 6B , in a state where the contact member 125 is located at the second position, the cam surface 125 A comes into contact with the lever 13 A of the sensor 13 . The contact member 125 may be a projection.

2.2.6 Spring 126

As shown in FIGS. 5A and 6A , the spring 126 is configured to move the contact member 125 toward the second position in the first position. In the present embodiment, the spring 126 is a pulling spring. One end of the spring 126 is attached to the protrusion 123 . The other end of the spring 126 is attached to a particular projection formed in the housing 2 . The spring 126 maybe a torsion spring configured to push the protrusion 123 such that the contact member moves from the first position to the second position.

2.2.7 Stopper 127

As shown in FIG. 5A , in a state where the cover 3 is located at the closed position, the stopper 127 stops the sector gear 122 from rotating from the sector first position to the sector second position.

In detail, as shown in FIG. 10 , the stopper 127 extends from the cover 3 . In the present embodiment, the stopper 127 extends from a hinge 31 of the cover 3 . The stopper 127 may be attached to the cover 3 . As shown in FIG. 11 , in a state where the cover 3 is located at the closed position, the stopper 127 extends from the cover 3 toward the sector gear 122 . The stopper 127 extends in the direction in which the axis A 11 (see FIG. 5A ) extends.

As shown in FIG. 5A , in a state where the cover 3 is located at the closed position and the sector gear 122 is located at the sector first position, the stopper 127 contacts the protrusion 124 . As a result, the stopper 127 stops the rotation of the sector gear 122 from the sector first position to the sector second position.

On the other hand, as shown in FIGS. 5A and 6A , in a case where the cover 3 moves from the closed position to the open position, the stopper 127 moves in association with the cover 3 to allow the sector gear 122 to rotate from the sector first position to the sector second position. In detail, in a case where the cover 3 is moved from the closed position to the open position, the stopper 127 moves in association with the cover 3 and moves away from the protrusion 124 . As the stopper 127 moves away from the protrusion 124 , the sector gear 122 becomes rotatable from the sector first position to the sector second position. In other words, the stopper 127 permits the sector gear 122 to rotate from the sector first position to the sector second position. In a case where the stopper 127 moves away from the protrusion 124 , the sector gear 122 rotates from the sector first position to the sector second position by an elastic force of the spring 126 .

It is noted that, as shown in FIGS. 6A and 7 , in a case where the cover 3 moves from the open position to the closed position, the stopper 127 does not contact the protrusion 124 of the sector gear 122 since the sector gear 122 is located at the sector second position.

As shown in FIG. 7 and FIG. 5A , in a case where the sector gear 122 rotates from the sector second position to the sector first position by the power from the drive gear 121 in a state where the cover 3 in the closed position, the sector gear 122 is positioned in the sector first position as the protrusion 124 comes into contact with the stopper 127 after the sector gear 122 and the drive gear 121 are disengaged.

2.3 Sensor 3

As shown in FIG. 6B , in a state where the contact member 125 contacts the sensor 13 , the sensor 13 detects that the interlocking mechanism 12 is in the second state.

In the present embodiment, the sensor 13 is a limit switch provided with a lever 13 A. The lever 13 A is configured to move between a lever first position (see FIG. 5B ) and a lever second position (see FIG. 6B ).

As shown in FIG. 5B , in a state where the contact member 125 is located at the first position, the lever 13 A is not pressed by the contact member 125 and is located at the lever first position. In a state where the lever 13 A is located at the lever first position, the sensor 13 does not detect that the interlocking mechanism 12 is in the second state.

On the other hand, as shown in FIG. 6B , in a state where the contact member 125 is located at the second position, the lever 13 A is pressed by the contact member 125 and is located at the lever second position. In a state where the lever 13 A is located at the lever second position, the sensor 13 detects that the interlocking mechanism 12 is in the second state.

It is noted that the sensor 13 is not necessarily be limited to a limit switch as long as the sensor 13 can detect that the interlocking mechanism 12 is in the second state. For example, the sensor 13 may be a photo interrupter. In a case where the sensor 13 is a photo interrupter, the interlocking mechanism 12 does not have to have the contact member 125 . The photo interrupter may be configured to detect a shielding plate that moves in association with the sector gear 122 , or may detect a notch or through hole formed on the sector gear 122 .

2.4 Separation Mechanism 14

As shown in FIGS. 1 and 3 , the separation mechanism 14 is configured to move the developing roller 71 Y from the contact position (see FIG. 1 ) to the separation position (see FIG. 3 ).

In detail, as shown in FIG. 12A , the separation mechanism 14 has a plurality of cam followers 141 Y, 141 M, 141 C and 141 K, a plurality of gears 142 Y, 142 M, 142 C and 142 K, a plurality of cams 143 Y, 143 M, 143 C and 143 K, and a cam 144 .

Each of the cam followers 141 M, 141 C and 141 K has the same structure as the cam follower 141 Y, each of the gears 142 M, 142 C and 142 K has the same structure as the gear 142 Y, and each of the cams 143 M, 143 C and 143 K has the same structure as the cam 143 Y. Therefore, in the following description, only the cam follower 141 Y, the gear 142 Y and the cam 143 Y will be described, and description on the cam followers 141 M, 141 C, 141 K, the gears 142 M, 142 C, 142 K, and the cams 143 M, 143 C, 143 K will be omitted.

2.4.1 Cam Followers 141 Y, 141 M, 141 C and 141 K

The cam follower 141 Y is a member for releasing the developing roller 71 Y (see FIG. 3 ) from the photosensitive drum 51 Y (see FIG. 3 ).

As shown in FIGS. 13A and 13B , the cam follower 141 Y is configured to be movable between a pressing position (see FIG. 13A ) and a pressure release position (see FIG. 13B ) in the second direction. The cam follower 141 Y is configured to be pulled toward the pressure release position by a tension spring not shown in the figure.

As shown in FIG. 13A , in a state where the cam follower 141 Y is located at the pressing position, the developing roller 71 Y (see FIG. 3 ) is located at the separation position.

In detail, in the present embodiment, the developer cartridge 7 Y has a separation member 72 Y. The drum unit 5 may have the separation member 72 Y. The separating member 72 Y is a member configured to move the developer cartridge 7 Y in a direction in which the developing roller 71 Y is spaced from the photosensitive drum 51 Y. When the cam follower 141 Y is located at the pressing position, the cam follower 141 Y presses the separation member 72 Y. In a state where the cam follower 141 Y presses the separating member 72 Y, the separating member 72 Y make the developer cartridge 7 Y be located at a position where the developing roller 71 Y is spaced from the photosensitive drum 51 Y. As a result, in a state where the cam follower 141 Y is located at the pressing position, the developing roller 71 Y (see FIG. 3 ) is located at the separation position.

On the other hand, in a state where the cam follower 141 Y is at the pressure release position, the developing roller 71 Y (see FIG. 1 ) is located at the contact position as shown in FIG. 13B .

In detail, in a state where the cam follower 141 Y is located at the pressure release position, the cam follower 141 Y is spaced from the separation member 72 Y and releases the pressure on the separation member 72 Y. Then, the separating member 72 Y permits the developer cartridge 7 Y to move to the position where the developing roller 71 Y contacts the photosensitive drum 51 Y. As a result, in a state where the cam follower 141 Y is located at the pressure release position, the developing roller 71 Y (see FIG. 1 ) is located at the contact position.

As shown in FIGS. 14A and 14B , the cam follower 141 Y is configured to be rotatable about the axis A 12 , between the first rotational position (see FIG. 14A ) and the second rotational position (see FIG. 14B ). The axis A 12 extends in the second direction.

As shown in FIG. 14A , in a state where the cam follower 141 Y is located at the first rotational position, the cam follower 141 Y is capable of contacting the cam 143 Y.

As shown in FIG. 14B , in a state where the cam follower 141 Y is located at the second rotational position, the cam follower 141 Y is unable to contact the cam 143 Y. Therefore, in a state where the cam follower 141 Y is located at the second rotational position, the cam follower 141 Y is maintained to stay at the pressure release position regardless of the position of the cam 143 Y.

As shown in FIG. 14A , the cam follower 141 Y has a shaft 1411 , a protrusion 1412 , and a protrusion 1413 .

The shaft 1411 is configured to extend in the second direction along the axis A 12 . In a state where the cam follower 141 Y is located at the pressing position, the shaft 1411 presses the separation member 72 Y.

The protrusion 1412 extends from the shaft 1411 in the radial direction of the shaft 1411 .

The protrusion 1413 extends from the shaft 1411 in the radial direction of the shaft 1411 . The protrusion 1413 is located at a position spaced from the protrusion 1412 .

2.4.2 Gear 142 Y

As shown in FIG. 14A , the gear 142 Y is configured to be rotatable about the axis A 13 , which extends in the second direction. The axis A 13 is located at a position spaced from the axis A 12 . The gear 142 Y has one surface 1421 and the other surface 1422 in the second direction.

2.4.3 Cam 143 Y

As shown in FIG. 14A , when the cam 143 Y rotates in a state where the cam follower 141 Y is located at the first rotational position, the cam 143 Y presses the protrusion 1412 of the cam follower 141 Y in the second direction. As a result, the cam 143 Y moves the cam follower 141 Y from the pressure release position (see FIG. 13B ) to the pressing position (see FIG. 13A ). In a state where the cam 143 Y is separated from the protrusion 1412 of the cam follower 141 Y, the cam 143 Y allows the cam follower 141 Y to move from the pressing position (see FIG. 13A ) to the pressure release position (see FIG. 13B ).

The cam 143 Y is arranged on the one surface 1421 of the gear 142 Y. The cam 143 Y extends from the one surface 1421 of the gear 142 Y. The cam 143 Y may be attached to the one surface 1421 of the gear 142 Y. The cam 143 Y is rotatable about axis A 13 in association with the gear 142 Y. The cam 143 Y extends in the second direction and in the direction of rotation of the gear 142 Y.

2.4.3 Cam 144

As shown in FIGS. 12A and 12B , the cam 144 is configured to move the cam follower 141 Y from the first rotational position to the second rotational position in association with the movement of the cover 3 from the closed position to the open position. As described above, in a state where the cam follower 141 Y is located at the second rotational position, the cam follower 141 Y is located at the pressure release position. Therefore, the developing roller 71 Y (see FIG. 3 ) is located at the contact position. That is, the separation mechanism 14 permits the movement of the developing roller 71 Y from the separation position to the contact position in association with the movement of the cover 3 from the closed position to the open position.

On the other hand, the cam 144 is configured to move the cam follower 141 Y from the second rotation position to the first rotation position in association with the movement of the cover 3 from the open position to the closed position.

The cam 144 is connected to the hinge 31 of the cover 3 via a link. The cam 144 is movable in the first direction.

2.5 Drum Cleaners 15 Y, 15 M, 15 C and 15 K

Each of the drum cleaners 15 M, 15 C and 15 K has the same structure as the drum cleaner 15 Y. Therefore, in the following description, only the drum cleaner 15 Y will be described, and the descriptions on the drum cleaners 15 M, 15 C and 15 K will be omitted.

As shown in FIG. 1 , the drum cleaner 15 Y has a drum cleaning roller 151 Y. The drum cleaning roller 151 Y is configured to clean the photosensitive drum 51 Y. In other words, the drum cleaner 15 Y is configured to clean the photosensitive drum 51 Y.

2.6 Belt Cleaner 16

The belt cleaner 16 has a belt cleaning roller 161 . The belt cleaning roller 161 is configured to clean the belt 81 . In other words, the belt cleaner 16 is configured to clean the belt 81 .

2.7 Controller 17

As shown in FIG. 4 , the controller 17 is electrically connected to the sensor 13 . The controller 17 is configured to control the operation of the interlocking mechanism 12 , the separation mechanism 14 , the plurality of drum cleaners 15 Y, 15 M, 15 C and 15 K, the belt cleaner 16 , and the fixing device 9 .

Concretely, the controller 17 is a control circuit board configured to control the operation of the image forming apparatus 1 . The controller 17 is equipped with a processor 171 and a memory 172 . In other words, the image forming apparatus 1 has a memory 172 . The processor 171 includes, for example, a CPU (central processing unit). The memory 172 includes a non-volatile memory. The controller 17 may also have an ASIC (application-specific integrated circuit).

When the controller 17 locate the developing roller 71 Y at the contact position, the controller 17 writes, in the memory 172 , information indicating that the developing roller 71 Y is to be located at the contact position. On the other hand, in a case where the controller 17 locates the developing roller 71 Y at the separation position, the controller 17 writes, in the memory 172 , information indicating that the developing roller 71 Y is in the separation position.

3. Control of Image Forming Apparatus 1

Next, referring to FIG. 15 and FIG. 16 , the control of the image forming apparatus 1 will be described.

As shown in FIG. 15 , in a state where the power switch 11 in the on state, the controller 17 writes the information that the developing roller 71 Y is in the contact position to the memory 172 (S 1 ) before starting a printing process (S 3 ), and activates the separation mechanism 14 to locate the developing roller 71 Y at the contact position (S 2 ).

After the printing process (S 3 ) is completed, the controller 17 operates the separation mechanism 14 to locate the developing roller 71 Y at the separation position (S 4 ), and writes the information that the developing roller 71 Y is located at the separation position in the memory 172 (S 5 ).

That is, in a case where the state of the power switch 11 is changed from the on state to the off state, and power is no longer supplied to the controller 17 , the developing roller 71 Y is located at the separation position, and in the memory 172 , it has been written that the developing roller 71 Y is located at the separation position.

Next, in a case where the state of the power switch 11 is changed from the off state to the on state, and power supply to the controller 17 is started, as shown in FIG. 16 , in a case where the cover 3 is located at the closed position (S 11 : YES), the controller 17 refers to the memory 172 to determine whether it is recorded that the developing roller 71 Y is located at the separation position (S 12 ).

In a case where it is recorded in the memory 172 that the developing roller 71 Y is in the separation position (S 12 : YES), the controller 17 determines whether the sensor 13 detects that the interlocking mechanism 12 is in the second state (S 13 ).

In a case where it is recorded in the memory 172 that the developing roller 71 Y is located at the contact position when power supply to the controller 17 is started (S 12 : NO), the controller 17 performs a second warm-up process described below (S 16 ) without determining whether or not the sensor 13 detects that the interlocking mechanism 12 is in the second state.

3.1 First Warm-Up Process

In a case where power supply to the controller 17 is started and the sensor 13 does not detect that the interlocking mechanism 12 is in the second state (S 13 : NO), the controller 17 performs a first warm-up process (S 14 ). It is noted that “a case where the sensor 13 does not detect that the interlocking mechanism 12 is in the second state” means, in other words, a case where the cover 3 has not been moved from the closed position to the open position while the power is not supplied to the controller 17 . In such a case, the developing roller 71 Y (see FIG. 3 ) is located at the separation position, and the information that the developing roller 71 Y is located at the separation position is recorded in the memory 172 .

In the first warm-up process (S 14 ), the controller 17 does not rotate the cam 143 Y of the separation mechanism 14 while the developing roller 71 Y is located at the separation position, as shown in FIG. 12B . As a result, the cam follower 141 Y is kept at the pressing position and the developing roller 71 Y is kept at the separating position.

That is, in the first warm-up process (S 14 ), the controller 17 causes the separation mechanism 14 to make the developing roller 71 Y stay at the separation position. In other words, in a case where the sensor 13 does not detect that the interlocking mechanism 12 is in the second state when power supply to the controller 17 is started, the separating mechanism 14 makes the developing roller 71 Y located at the separation position remain at the separation position.

Further, in the first warm-up process (S 14 ), the controller 17 does not rotate the photosensitive drums 51 Y, 51 M, 51 C and 51 K (see FIG. 3 ), the drum cleaning rollers 151 Y, 151 M, 151 C and 151 K (see FIG. 3 ), and the belt cleaning rollers 161 (see FIG. 3 ).

That is, in the first warm-up process (S 14 ), the controller 17 does not allow the drum cleaner 15 Y to clean the photosensitive drum 51 Y, does not allow the drum cleaner 15 M to clean the photosensitive drum 51 M, does not allow the drum cleaner 15 C to clean the photosensitive drum 51 C, and does not allow the drum cleaner 15 K to clean the photosensitive drum 51 K. In other words, in a case where the sensor 13 does not detect that the interlocking mechanism 12 is in the second state when power supply to the controller 17 is started, the drum cleaner 15 Y does not clean the photosensitive drum 51 Y, the drum cleaner 15 M does not clean the photosensitive drum 51 M, the drum cleaner 15 C does not clean the photosensitive drum 51 C and the drum cleaner 15 K does not clean the photosensitive drum 51 K.

In the first warm-up process (S 14 ), the controller 17 does not allow the belt cleaner 16 to clean the belt 81 . In other words, in a case where the sensor 13 does not detect that the interlocking mechanism 12 is in the second state when power supply to the controller 17 is started, the belt cleaner 16 does not clean the belt 81 .

In the first warm-up process (S 14 ), the controller 17 raises the temperature of the fixing device 9 to a particular target temperature.

3.2 Second Warm-Up Process

On the other hand, in a case where the sensor 13 detects that the interlocking mechanism 12 is in the second state (S 13 : YES) when power supply to the controller 17 is started, the controller 17 performs a second warm-up process (S 16 ). It is noted that “a case where the sensor 13 detects that the interlocking mechanism 12 is in the second state” means, in other words, a case where the cover 3 moves from the closed position to the open position while the power is not supplied to the controller 17 . In such a case, the developing roller 71 Y (see FIG. 1 ) is located at the contact position. In contrast, the fact that the developing roller 71 Y is located at the separation position is recorded in the memory 172 .

Therefore, in a case where the sensor 13 detects that the interlocking mechanism 12 is in the second state (S 13 : YES) when power supply to the controller 17 is started, the controller 17 writes to the memory 172 that the developing roller 71 Y is located at the contact position (S 15 ) and performs the second warm-up process (S 16 ).

In the second warm-up process (S 16 ), the controller 17 rotates the cam 143 Y of the separation mechanism 14 in a state where the cam follower 141 Y is located at the first rotation position as shown in FIG. 14A . Then, the cam follower 141 Y moves from the pressure release position (see FIG. 13B ) to the pressing position (see FIG. 13A ), and the developing roller 71 Y moves from the contact position (see FIG. 1 ) to the separation position (see FIG. 3 ).

It is noted that, in the second warm-up process (S 16 ), the controller 17 causes the separation mechanism 14 to move the developing roller 71 Y located at the contact position to the separation position. In other words, in a case where the sensor 13 detects that the interlocking mechanism 12 is in the second state when power supply to the controller 17 is started, the separation mechanism 14 moves the developing roller 71 Y, which is located at the contact position, to the separation position.

Further, in the second warm-up process (S 16 ), the controller 17 rotates the photosensitive drums 51 Y, 51 M, 51 C and 51 K (see FIG. 1 ), the drum cleaning rollers 151 Y, 151 M, 151 C and 151 K (see FIG. 1 ), and the belt cleaning roller 161 (see FIG. 1 ).

That is, in the second warm-up process (S 16 ), the controller 17 causes the drum cleaner 15 Y to clean the photosensitive drum 51 Y, the drum cleaner 15 M to clean the photosensitive drum 51 M, the drum cleaner 15 C to clean the photosensitive drum 51 C, and the drum cleaner 15 K to clean the photosensitive drum 51 K. In other words, in a case where the sensor 13 detects that the interlocking mechanism 12 is in the second state when power supply to the controller 17 is started, the drum cleaner 15 Y cleans the photosensitive drum 51 Y, the drum cleaner 15 M cleans the photosensitive drum 51 M, the drum cleaner 15 C cleans the photosensitive drum 51 C, and the drum cleaner 15 K cleans the photosensitive drum 51 K.

In the second warm-up process (S 16 ), the controller 17 causes the belt cleaner 16 to clean the belt. In other words, in a case where the sensor 13 detects that the interlocking mechanism 12 is located at the second state when power supply to the controller 17 is started, the belt cleaner 16 cleans the belt 81 .

Also, in the second warm-up process (S 16 ), the controller 17 raises the temperature of the fixing device 9 to a particular target temperature.

4. Effects

(1) According to the image forming apparatus 1 , as shown in FIGS. 12A and 12B , the cam follower 141 Y of the separation mechanism 14 moves from the first rotational position (see FIG. 12A ) to the second rotational position (see FIG. 12B ) in association with the movement of the cover 3 from the closed position (see FIG. 12A ) to the open position (see FIG. 12B ). At the second rotational position, the cam follower 141 Y releases the pressure of the developer cartridge 7 Y on the separating member 72 Y (see FIG. 13B ). The release of the pressure on the separation member 72 Y of the developer cartridge 7 Y causes the developing roller 71 Y to move from the separation position (see FIG. 3 ) to the contact position (see FIG. 1 ).

That is, the separation mechanism 14 allows the developer roller 71 Y to move from the separation position to the contact position in association with the movement of the cover 3 from the closed position to the open position. As a result, when the cover 3 is moved from the closed position to the open position while no power is supplied to the controller 17 , the developing roller 71 Y moves from the separation position to the contact position.

As shown in FIG. 5A and FIG. 6A , in a case where the cover 3 moves from the closed position to the open position while no power is supplied to the controller 17 , the state of the interlocking mechanism 12 switches from the first state (see FIG. 5A ) to the second state (see FIG. 6A ). Thereafter, as shown in FIG. 6A and FIG. 7 , the interlocking mechanism 12 remains in the second state even though the cover 3 located at the open position moves to the closed position.

Therefore, in a case where the cover 3 is moved from the closed position to the open position while no power is supplied to the controller 17 , the history of the cover 3 moving from the closed position to the open position will remain in the interlocking mechanism 12 .

Then, as shown in FIG. 16 , in a case where the sensor 13 detects that the interlocking mechanism 12 is in the second state (S 13 : YES) when power supply to the controller 17 is started, in the second warm-up process (S 16 ), the controller 17 causes the separation mechanism 14 to move the developing roller 71 Y, which is located at the contact position (see FIG. 1 ), to the separation position (see FIG. 3 ).

On the other hand, in a case where the sensor 13 does not detect that the interlocking mechanism 12 is in the second state (S 13 : NO) when power supply to the controller 17 is started, the controller 17 causes, in the first warm-up process (S 14 ), the separating mechanism 14 to keep the developing roller 71 Y, which is located at the separation position, at the contact position without moving the same to the contact position.

Accordingly, unnecessary contact between the developing roller 71 Y and the photosensitive drum 51 Y can be reduced.

(2) According to the image forming apparatus 1 , in a case where the cover 3 is moved from the closed position (see FIG. 1 ) to the open position (see FIG. 2 ) while the power is not supplied to the controller 17 , foreign objects from outside are likely to enter the housing 2 due to the cover 3 being located at the open position.

Therefore, as shown in FIG. 16 , in a case where the sensor 13 detects the interlocking mechanism 12 is in the second state (S 13 : YES) when power supply to the controller 17 is started, the controller 17 causes, in the second warm-up process (S 16 ), the belt cleaner 16 (see FIG. 1 ) to clean the belt 81 (see FIG. 1 ). As a result, even though foreign objects that have entered the housing 2 adhere to the belt 81 , the foreign objects can be removed.

On the other hand, in a case where the cover 3 is not moved from the closed position to the open position while no power is supplied to the controller 17 , there is little possibility of foreign objects from outside entering the housing 2 .

Therefore, in a case where the sensor 13 does not detect that the interlocking mechanism 12 is in the second state (S 13 : NO) when power supply to the controller 17 is started, the controller 17 does not cause, in the first warm-up process (S 14 ), the belt cleaner 16 to clean the belt 81 . This can reduce unnecessary belt cleaning.

(3) According to the image forming apparatus 1 , in a case where the sensor 13 detects that the interlocking mechanism 12 is in the second state (S 13 : YES) when power supply to the controller 17 is started, the controller 17 causes, in the second warm-up process (S 16 ), the drum cleaner 15 Y to clean the photosensitive drum 51 Y. (S 13 : YES), the controller 17 causes the drum cleaner 15 Y to clean the photosensitive drum 51 Y in the second warm-up process (S 16 ). In this way, even though the foreign objects entering the housing 2 and adhere to the photosensitive drum 51 Y, the foreign objects can be removed.

On the other hand, in a case where the sensor 13 does not detect that the interlocking mechanism 12 is in the second state (S 13 : NO) when power supply to the controller 17 is started, the controller 17 does not cause the drum cleaner 15 Y to clean the photosensitive drum 51 Y in the first warm-up process (S 14 ). This can reduce unnecessary drum cleaning.