Belt unit and image forming device equipped therewith
View Patent ↗There is provided a belt unit including: a fixed frame at which a transfer roller is provided; plural fixed side supporting rollers provided at the fixed frame; a movable frame that is swingably mounted to the fixed frame, and at which plural transfer rollers are provided; a movable side supporting roller provided at the movable frame; and an endless belt stretched around the fixed side supporting rollers and the movable side supporting roller, and contacting the transfer roller provided at the fixed frame and the transfer rollers supported at the movable frame, and contacting plural photoreceptor drums, wherein a swinging center of the movable frame is a center of belt portions at both sides of the swinging center, and in a monochrome mode, the movable frame is swung and moves the belt away from the photoreceptor drums other than the photoreceptor drum that is used in the monochrome mode.
1. A belt unit comprising:
a fixed frame at which a transfer roller is provided;
a plurality of fixed side supporting rollers provided at the fixed frame;
a movable frame that is swingably mounted to the fixed frame, and at which a plurality of transfer rollers are provided;
a movable side supporting roller provided at the movable frame; and
an endless belt stretched around the fixed side supporting rollers and the movable side supporting roller, and contacting the transfer roller provided at the fixed frame and the transfer rollers supported at the movable frame, and contacting a plurality of photoreceptor drums,
wherein a swinging center of the movable frame is a center of belt portions at both sides of the swinging center, and
in a monochrome mode, the movable frame is swung and moves the belt away from the photoreceptor drums other than the photoreceptor drum that is used in the monochrome mode, wherein two rollers are provided as the fixed side supporting rollers, and
the swinging center is positioned on a line that connects a central point of a line connecting rotational centers of the two rollers, and a rotational center of the movable side supporting roller in a color mode.
2. The belt unit of claim 1 , wherein the movable side supporting roller is a steering roller that moves in a direction orthogonal to a feeding direction of the belt and carries out adjustment of meandering of the belt.
3. The belt unit of claim 2 , wherein an urging portion that urges the steering roller so as to stretch the belt is provided.
4. The belt unit of claim 1 , wherein the fixed frame extends to a position at which the transfer rollers provided at the movable frame are disposed, and
an electricity supplying mechanism, that supplies electricity via the fixed frame to the transfer rollers provided at the movable frame, is provided.
5. The belt unit of claim 4 , wherein a movable frame side conductive plate portion, to which electricity is supplied from the fixed frame side, is provided at the movable frame, and
a fixed frame side conductive plate portion, that has a spring portion that contacts the conductive plate portion while urging the conductive plate portion, is provided at the fixed frame.
6. The belt unit of claim 1 , wherein the belt is an intermediate transfer belt or a sheet conveying belt.
7. An image forming device comprising the belt unit of claim 1 .
8. A belt unit comprising:
a fixed frame at which a transfer roller is provided;
a plurality of fixed side supporting rollers provided at the fixed frame;
a movable frame that is swingably mounted to the fixed frame, and at which a plurality of transfer rollers are provided;
a movable side supporting roller provided at the movable frame; and
an endless belt stretched around the fixed side supporting rollers and the movable side supporting roller, and contacting the transfer roller provided at the fixed frame and the transfer rollers supported at the movable frame, and contacting a plurality of photoreceptor drums,
wherein a swinging center of the movable frame is positioned substantially at a center between a belt portion at an upper side of the swinging center and a belt portion at a lower side of the swinging center,
in a monochrome mode, the movable frame is swung and moves the belt away from the photoreceptor drums other than the photoreceptor drum that is used in the monochrome mode,
the fixed frame extends to a position at which the transfer rollers provided at the movable frame are disposed,
an electricity supplying mechanism, that supplies electricity via the fixed frame to the transfer rollers provided at the movable frame, is provided,
a movable frame side conductive plate portion, to which electricity is supplied from the fixed frame side, is provided at the movable frame, and
a fixed frame side conductive plate portion, that has a spring portion that contacts the conductive plate portion while urging the conductive plate portion, is provided at the fixed frame.
9. The belt unit of claim 8 , wherein the movable side supporting roller is a steering roller that moves in a direction orthogonal to a feeding direction of the belt and carries out adjustment of meandering of the belt.
10. The belt unit of claim 9 , wherein an urging portion that urges the steering roller so as to stretch the belt is provided.
11. The belt unit of claim 8 , wherein the belt is an intermediate transfer belt or a sheet conveying belt.
12. An image forming device comprising the belt unit of claim 8 .
13. A belt unit comprising:
a fixed frame at which a transfer rover is provided;
a plurality of fixed side supporting rovers provided at the fixed frame;
a movable frame that is swingably mounted to the fixed frame, and at which a plurality of transfer rollers are provided:
a movable side supporting roller provided at the movable frame; and
an endless belt stretched around the fixed side supporting rollers and the movable side supporting roller, and contacting the transfer roller provided at the fixed frame and the transfer rollers supported at the movable frame, and contacting a plurality of photoreceptor drums, wherein a swinging center of the movable frame is a center of belt portions at both sides of the swinging center,
in a monochrome mode, the movable frame is swung and moves the belt away from the photoreceptor drums other than the photoreceptor drum that is used in the monochrome mode,
the fixed frame extends to a position at which the transfer rollers provided at the movable frame are disposed,
an electricity supplying mechanism, that supplies electricity via the fixed frame to the transfer rollers provided at the movable frame, is provided,
a movable frame side conductive plate portion, to which electricity is supplied from the fixed frame side, is provided at the movable frame, and
a fixed frame side conductive plate portion, that has a spring portion that contacts the conductive plate portion while urging the conductive plate portion, is provided at the fixed frame.
14. The belt unit of claim 13 , wherein
two rollers are provided as the fixed side supporting rollers, and
the swinging center is positioned on a line that connects a central point of a line connecting rotational centers of the two rollers, and a rotational center of the movable side supporting roller in a color mode.
15. The belt unit of claim 13 , wherein the movable side supporting roller is a steering roller that moves in a direction orthogonal to a feeding direction of the belt and carries out adjustment of meandering of the belt.
16. The belt unit of claim 15 , wherein an urging portion that urges the steering roller so as to stretch the belt is provided.
17. The belt unit of claim 13 , wherein the belt is an intermediate transfer belt or a sheet conveying belt.