US 2021/0200140 A1Published application

Image forming apparatus

AssigneeBrother Kogyo Kabushiki Kaisha

InventorsToshiyuki SANO, Shintaro SAKAGUCHI, Yusuke IKEGAMI

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Abstract

An image forming apparatus, having a casing, a cover, a photosensitive drum, a developing roller, a photo-interrupter, a moving mechanism to move the developing roller between a contacting position and a separated position, and a controller, is provided. The moving mechanism has a cam including, a first cam portion, a phase-detector wall including a first slit and a second slit, and a cam follower. When the cover moves from the open position to the closed position, the controller conducts a first initializing control to cause the cam to rotate in a reverse direction, and after detecting the first slit based on a time period, in which light in the photo-interrupter passes through one of the first slit and the second slit, cause the cam to stop rotating.

Claims13

Dependent claims

An image forming apparatus, comprising:

a casing having an opening;
a cover movable between a closed position, at which the opening is closed by the cover, and an open position, at which the opening is exposed;
a photosensitive drum;
a developing roller;
a photo-interrupter including a light-emitter and a light-receiver;
a moving mechanism configured to move the developing roller between a contacting position, at which the developing roller contacts the photosensitive drum, and a separated position, at which the developing roller is separated from the photosensitive drum, the moving mechanism comprising;
a cam configured to rotate about a rotation axis bidirectionally in a normal direction and a reverse direction, the cam including:
a first cam portion;
and
a phase-detector wall extending in a circumferential direction centered at the rotation axis of the cam, the phase-detector wall having a first slit, through which light emitted from the light-emitter is allowed to pass the phase-detector wall when the developing roller is at the separated position, and a second slit, through which the light emitted from the light-emitter is allowed to pass the phase-detector wall when the developing roller is at the contacting position, the second slit having a different size in the circumferential direction from the first slit;
and
a cam follower being slidably movable between a protrusive position and a standby position and being pivotable between an operable position and an inoperable position, the cam follower including a contacting portion, the contacting portion being configured to contact the first cam portion, and an arm, the arm extending in a direction different from the contacting portion;
and
a controller configured to, when the cover moves from the open position to the closed position, conduct a first initializing control, in which the controller causes the cam to rotate in the reverse direction and, after detecting the first slit based on a time period, in which the light emitted from the light-emitter passes through one of the first slit and the second slit, causes the cam to stop rotating.

11 more elements

An image forming apparatus, comprising:

a casing having an opening;
a cover movable between a closed position, at which the opening is closed by the cover, and an open position, at which the opening is exposed;
a photosensitive drum;
a developing roller;
a detector;
a moving mechanism configured to move the developing roller between a contacting position, at which the developing roller contacts the photosensitive drum, and a separated position, at which the developing roller is separated from the photosensitive drum, the moving mechanism comprising:
a cam rotatable about a rotation axis bidirectionally in a normal direction and a reverse direction, the cam including:
a phase-detector wall extending in a circumferential direction centered at the rotation axis of the cam, the phase-detector wall having:
a first slit having a first width in the circumferential direction, the first slit being configured to be detected by the detector when the developing roller is at the separated position, and
a second slit having a second width in the circumferential direction, the second width differing from the first width, the second slit being configured to be detected by the detector when the developing roller is at the contacting position;
and
a controller,
wherein, when the cover moves from the open position to the closed position, the controller is configured to:
control the cam to start rotating in the reverse direction;
after causing the cam to rotate in the reverse direction, and after the first slit is detected by the detector, control the cam to stop rotating;
after causing the cam to stop rotating in the reverse direction, control the cam to rotate in the normal direction;
and
after causing the cam to rotate in the normal direction, control the cam to stop rotating at a position where the first slit is detected by the detector.

15 more elements

Dependencies are inferred from the claim text.