Abstract: A sheet feeder includes a roller, a reflector, a sensor, and a rotating speed detector. The reflector is integrally attached to the roller, the reflector including first reflecting surfaces and second reflecting surfaces arranged alternately along a circumference direction of the roller. The sensor includes a light emitter and a light receiver. The rotating speed detector is configured to detect a rotating speed of the roller based on a result of the detection by the sensor. Each of the first reflecting surfaces reflects the inspection light at a first reflection ratio, and provides a first reflection light path along which the inspection light is directed to the light receiver. Each of the second reflecting surfaces reflects the inspection light at a second reflection ratio smaller than the first reflection ratio, and provides a second reflection light path along which the inspection light is directed outside the light receiver.

Abstract: A sheet feeder includes a roller, a reflector, a sensor, and a rotating speed detector. The reflector is integrally attached to the roller, the reflector including first reflecting surfaces and second reflecting surfaces arranged alternately along a circumference direction of the roller. The sensor includes a light emitter and a light receiver. The rotating speed detector is configured to detect a rotating speed of the roller based on a result of the detection by the sensor. Each of the first reflecting surfaces reflects the inspection light at a first reflection ratio, and provides a first reflection light path along which the inspection light is directed to the light receiver. Each of the second reflecting surfaces reflects the inspection light at a second reflection ratio smaller than the first reflection ratio, and provides a second reflection light path along which the inspection light is directed outside the light receiver.

Abstract: An image forming apparatus includes a front cover and a maintenance cover. The front cover has a support section, an interference section, and a projection. The support section is supported by a housing of the image forming apparatus so as to be pivotable about a pivot axis. The interference section extends rearward from an edge of the front cover. The projection is located on a contact surface that comes in or out of contact with a specific section of the maintenance cover as the front cover is closed or opened with the maintenance cover in a closed state. The specific section of the maintenance cover has a hole. The projection fits in the hole.

Abstract: An image forming apparatus includes a front cover and a maintenance cover. The front cover has a support section, an interference section, and a projection. The support section is supported by a housing of the image forming apparatus so as to be pivotable about a pivot axis. The interference section extends rearward from an edge of the front cover. The projection is located on a contact surface that comes in or out of contact with a specific section of the maintenance cover as the front cover is closed or opened with the maintenance cover in a closed state. The specific section of the maintenance cover has a hole. The projection fits in the hole.

Abstract: A metal belt (300) is an endless belt formed of a strip body. The metal belt (300) includes a belt overlapping portion in which at least two ring pieces (310a, 320a) formed by deformation due to a compressive stress inherent in the belt doubly overlap in a ring radial direction in a natural state where no external force is applied. Further, the metal belt (300) has a cross-sectional shape convex radially outwardly in a cross-section perpendicular to a circumferential direction of the belt in a state reached by annularly spreading the belt in the natural state.

Abstract: A metal belt (300) is an endless belt formed of a strip body. The metal belt (300) includes a belt overlapping portion in which at least two ring pieces (310a, 320a) formed by deformation due to a compressive stress inherent in the belt doubly overlap in a ring radial direction in a natural state where no external force is applied. Further, the metal belt (300) has a cross-sectional shape convex radially outwardly in a cross-section perpendicular to a circumferential direction of the belt in a state reached by annularly spreading the belt in the natural state.

Abstract: A powder conveying device includes a first conveying unit, a second conveying unit, a conveying member, a powder pulverizing member, and a protective member. The first conveying unit has a lower end. The second conveying unit has one end connected to the lower end. The conveying member is disposed in the second conveying unit and includes a shaft member and a protruding portion formed around the shaft member, and conveys the powder. The powder pulverizing member is disposed in the first conveying unit so as to be able to oscillate. The protective member is attached to the powder pulverizing member and makes contact with the protruding portion of the conveying member. A contact state between the protective member and the protruding portion changes according to a rotation angle of the conveying member, and the protective member and the powder pulverizing member oscillate due to changes in the contact state.

Abstract: A powder conveying device includes a first conveying unit, a second conveying unit, a conveying member, a powder pulverizing member, and a protective member. The first conveying unit has a lower end. The second conveying unit has one end connected to the lower end. The conveying member is disposed in the second conveying unit and includes a shaft member and a protruding portion formed around the shaft member, and conveys the powder. The powder pulverizing member is disposed in the first conveying unit so as to be able to oscillate. The protective member is attached to the powder pulverizing member and makes contact with the protruding portion of the conveying member. A contact state between the protective member and the protruding portion changes according to a rotation angle of the conveying member, and the protective member and the powder pulverizing member oscillate due to changes in the contact state.

Abstract: A driving mechanism includes: a looped metallic transmission belt; a first shaft member; a second shaft member; and a pulley that is connected to the second shaft member so as to be rotatable about a second rotational axis, in which the first shaft member includes: a rotatably supported portion that is disposed at one end; and an extended portion that is disposed at another end so as to be continuous with the rotatably supported portion, in which a portion between the contact portion and the rotatably supported portion is flexurally deformed, the extended portion being rotatable about a diagonal rotational axis that is inclined at a predetermined angle relative to the first rotational axis, and the pulley includes a inclined outer surface that is inclined, such that a portion that is most separated from the first shaft member is substantially parallel with the extended portion.

Abstract: A cooling mechanism for a photoreceptor includes: a photoreceptor of cylindrical shape; a pair of flanges respectively attached to both ends in an axial direction of the photoreceptor; a rotational shaft that is inserted into a shaft center of the photoreceptor; a holder that is disposed to face a first flange and rotatably supports the rotational shaft; and a main body frame that supports the holder. In such a cooling mechanism for a photoreceptor, an air duct is configured by the through hole formed in the flange and the concave portion formed on the holder, and discharges air flow generated inside the photoreceptor to the outside thereof.

Abstract: A driving mechanism includes: a looped metallic transmission belt; a first shaft member; a second shaft member; and a pulley that is connected to the second shaft member so as to be rotatable about a second rotational axis, in which the first shaft member includes: a rotatably supported portion that is disposed at one end; and an extended portion that is disposed at another end so as to be continuous with the rotatably supported portion, in which a portion between the contact portion and the rotatably supported portion is flexurally deformed, the extended portion being rotatable about a diagonal rotational axis that is inclined at a predetermined angle relative to the first rotational axis, and the pulley includes a inclined outer surface that is inclined, such that a portion that is most separated from the first shaft member is substantially parallel with the extended portion.

Abstract: A cooling mechanism for a photoreceptor includes: a photoreceptor of cylindrical shape; a pair of flanges respectively attached to both ends in an axial direction of the photoreceptor; a rotational shaft that is inserted into a shaft center of the photoreceptor; a holder that is disposed to face a first flange and rotatably supports the rotational shaft; and a main body frame that supports the holder. In such a cooling mechanism for a photoreceptor, an air duct is configured by the through hole formed in the flange and the concave portion formed on the holder, and discharges air flow generated inside the photoreceptor to the outside thereof.

Abstract: A roller member urging mechanism includes: a roller member having a roller shaft and coming in contact with a predetermined member; a casing for holding the roller member, the casing being electrically insulative; a bearing for receiving the roller shaft, the bearing being provided in the casing slidably in a direction substantially orthogonal to the roller shaft of the roller member, the bearing being electrically conductive; and a strip member provided in the casing near the bearing and serving as a contact for supplying electricity to the roller member. The strip member being a spring-like single member operable to come in contact with the bearing to press the roller member against the predetermined member through the bearing.

Abstract: A controller of an image forming apparatus determines whether switching of a monochromatic recording mode to a color recording mode is necessary or not. In the case where the controller determines that the switching is necessary, the controller controls stepping motors of respective image forming units corresponding to respective colors of yellow, cyan, magenta and black to lower their outputs. Then, the controller controls a power transmission mechanism to execute a connecting operation so as to transmit a driving force to each of the image forming units corresponding to yellow, cyan and magenta. At the timing when the color printing should be performed, the controller controls respective developing rollers to start performing a developing operation in order of yellow, cyan, magenta and black.

Abstract: A roller member urging mechanism includes: a roller member having a roller shaft and coming in contact with a predetermined member; a casing for holding the roller member, the casing being electrically insulative; a bearing for receiving the roller shaft, the bearing being provided in the casing slidably in a direction substantially orthogonal to the roller shaft of the roller member, the bearing being electrically conductive; and a strip member provided in the casing near the bearing and serving as a contact for supplying electricity to the roller member. The strip member being a spring-like single member operable to come in contact with the bearing to press the roller member against the predetermined member through the bearing.

Abstract: An image forming apparatus having a cleaning mechanism for cleaning paper powder or toner pressed and remaining on the surface of the circumference of an endless belt is provided. The cleaning mechanism includes a rotational shaft part that is detachably and rotatably attached to a supporting frame. The supporting frame of the cleaning mechanism is turned with the rotation of the rotational shaft part so that the supporting frame of the cleaning mechanism faces the belt supporting frame, fixing both frames at a point where a cleaning member presses the surface of the circumference of the endless belt.

Abstract: A gear includes a gear main body and a plurality of teeth projecting on the outer circumferential surface of the gear main body. Each tooth has a plurality of crowned portions formed by arcuate bulges along a tooth trace direction. In the case of constructing a gear mechanism using this gear, mating gears are respectively engaged with the respective crowned portions.

Abstract: A controller of an image forming apparatus determines whether switching of a monochromatic recording mode to a color recording mode is necessary or not. In the case where the controller determines that the switching is necessary, the controller controls stepping motors of respective image forming units corresponding to respective colors of yellow, cyan, magenta and black to lower their outputs. Then, the controller controls a power transmission mechanism to execute a connecting operation so as to transmit a driving force to each of the image forming units corresponding to yellow, cyan and magenta. At the timing when the color printing should be performed, the controller controls respective developing rollers to start performing a developing operation in order of yellow, cyan, magenta and black.

Abstract: An image forming apparatus having a belt supporting frame for supporting an intermediate transfer belt is provided. The intermediate transfer belt is a multi-layered structure composed of at least an elastic layer on a substrate layer. When a percentage difference of a stretched length of an outer circumference of the intermediate transfer belt to an inner circumference thereof at a position of contact to the driving roller is A % and a percent difference of a length of stretched side of the belt driven and stretched by the driving roller to a length of non-stretched opposite side of the belt is B %, the intermediate transfer belt is configured so that ranges of A and A+B fall simultaneously into inequalities of 1<A<6 and 3<A+B<10.

Abstract: The positioning of an image read sensor for accurately reading the toner image on the belt member becomes easy. The image read sensor 21 is located on the supporting frame 26 provided to the casing of the image forming apparatus so that it faces the belt member such as an intermediate transfer belt 45 between the driving roller 46 and follower roller 48 when the belt unit is mounted to the casing of the apparatus. The supporting frame 26 is provided with shaft supporting recesses 27. The shaft member is supported for rotation in the belt unit such that it contacts the inside surface of the belt member and pushes the belt member outward at the position it faces the image read sensor across the belt member when the belt unit is mounted to the casing of the apparatus.