An image forming device includes: a main unit; an image bearing body; a belt unit; and a tension-applying mechanism. The belt unit is detachably mounted in the main unit and has a pair of supporting rollers supporting an endless belt thereon. The endless belt has an inner circumference side that con
An image forming device includes: a main unit; an image bearing body; a belt unit; and a tension-applying mechanism. The belt unit is detachably mounted in the main unit and has a pair of supporting rollers supporting an endless belt thereon. The endless belt has an inner circumference side that confronts the pair of supporting rollers and an outer circumference side opposite to the inner circumference side. The outer circumference side of a part of the endless belt defined between the pair of supporting rollers along an arrangement direction, in which the pair of supporting rollers are arranged, confronts the image bearing body when the belt unit is mounted in the main unit. The tension-applying mechanism is provided in the main unit. When the belt unit is mounted in the main unit, the tension-applying mechanism urges one supporting roller among the pair of supporting rollers in a direction of separating the one supporting roller away from the other supporting roller, thereby applying tension to the endless belt.
대표청구항▼
What is claimed is: 1. An image forming device, comprising: a main unit; an image bearing body which bears a developer image thereon and which is provided in the main unit; a belt unit detachably mounted in the main unit and having a pair of supporting rollers supporting an endless belt thereon, th
What is claimed is: 1. An image forming device, comprising: a main unit; an image bearing body which bears a developer image thereon and which is provided in the main unit; a belt unit detachably mounted in the main unit and having a pair of supporting rollers supporting an endless belt thereon, the endless belt having an inner circumference side that confronts the pair of supporting rollers and an outer circumference side opposite to the inner circumference side, the outer circumference side of a part of the endless belt defined between the pair of supporting rollers along an arrangement direction, in which the pair of supporting rollers are arranged, confronting the image bearing body when the belt unit is mounted in the main unit; and a tension-applying mechanism that is provided in the main unit and that, when the belt unit is mounted in the main unit, urges one supporting roller among the pair of supporting rollers in a direction of separating the one supporting roller away from the other supporting roller, thereby applying tension to the endless belt. 2. An image forming device as claimed in claim 1, wherein the tension-applying mechanism includes: a coil spring which has a pair of opposite ends, one end among the pair of opposite ends being fixed to the main unit; and an engaging part connected to the other end among the pair of opposite ends of the coil spring, and wherein when the belt unit is mounted in the main unit, the rotational shaft of the one supporting roller engages with the engaging part and extends the coil spring. 3. An image forming device as claimed in claim 1, wherein the belt unit includes: a pair of attachment parts which rotatably support a pair of opposite ends of a rotational shaft of the one supporting roller; a connecting part that is elongated to connect the pair of attachment parts with each other, and wherein the tension-applying mechanism includes: an urging spring having a pair of opposite ends, one end of which is connected to the main unit; and an engaging part connected to the other end among the pair of opposite ends of the urging spring, and wherein when the belt unit is mounted in the main unit, the longitudinal center of the connecting part engages with the engaging part and elastically deforms the urging spring. 4. An image forming device as claimed in claim 1, wherein the endless belt has a linear expansion coefficient of 0.00015 cm/cm/�� C. or greater. 5. An image forming device, comprising: a main unit; an image bearing body which bears a developer image thereon and which is provided in the main unit; a belt unit detachably mounted in the main unit and having a first supporting roller, a second supporting roller, and at least one third supporting roller supporting an endless belt thereon, the at least one third supporting roller being located at a position that is separate from an imaginary plane, on which the first and second supporting rollers are located, in a direction perpendicular to the imaginary plane, the endless belt having an inner circumference side that confronts the first supporting roller, the second supporting roller, and the at least one third supporting roller and an outer circumference side opposite to the inner circumference side, the outer circumference side of a part of the endless belt defined between the first supporting roller and the second supporting roller along an arrangement direction, in which the first supporting roller and the second supporting roller are arranged, confronting the image bearing body when the belt unit is mounted in the main unit; and a tension-applying mechanism that is provided in the main unit and that, when the belt unit is mounted in the main unit, urges one supporting roller among the first supporting roller and the second supporting roller in a direction of separating the one supporting roller away from the other supporting roller among the first supporting roller and the second supporting roller, thereby applying tension to the endless belt. 6. An image forming device as claimed in claim 5, wherein the tension-applying mechanism includes: a coil spring which has a pair of opposite ends, one end among the pair of opposite ends being fixed to the main unit; and an engaging part connected to the other end among the pair of opposite ends of the coil spring, and wherein when the belt unit is mounted in the main unit, the rotational shaft of the one supporting roller engages with the engaging part and extends the coil spring. 7. An image forming device as claimed in claim 5, wherein the belt unit includes: a pair of attachment parts which rotatably support a pair of opposite ends of a rotational shaft of the one supporting roller; a connecting part that is elongated to connect the pair of attachment parts with each other, and wherein the tension-applying mechanism includes: an urging spring having a pair of opposite ends, one end of which is connected to the main unit; and an engaging part connected to the other end among the pair of opposite ends of the urging spring, and wherein when the belt unit is mounted in the main unit, the longitudinal center of the connecting part engages with the engaging part and elastically deforms the urging spring. 8. An image forming device as claimed in claim 5, wherein the endless belt has a linear expansion coefficient of 0.00015 cm/cm/�� C. or greater. 9. An image forming device, comprising: a main unit; a belt unit detachably mounted in the main unit and having a plurality of supporting rollers supporting an endless belt thereon, the endless belt having an inner circumference side that confronts the pair of supporting rollers, the belt unit farther having an engagement part and a spring member, the spring member being connected to one supporting roller among the plurality of supporting rollers at its one end and being connected to the engagement part at its other end; and an engaging member that is provided in the main unit and that engages with the engagement part and presses the one supporting roller against the inner circumference side of the endless belt via the spring member when the belt unit is mounted in the main unit. 10. A belt unit detachably mountable in an image forming device, the belt unit comprising: a frame that is configured so as to be capable of being detachably mounted in a main unit of an image forming device; a plurality of supporting rollers rotatably supported on the frame and supporting an endless belt thereon, the endless belt having an inner circumference side that confronts the pair of supporting rollers; a spring member which is connected to one supporting roller among the plurality of supporting rollers at its one end; and an engagement part which is connected to the other end of the spring member, the engagement part being configured to engage with an engaging member provided in the main unit of the image forming device and to press the one supporting roller against the inner circumference side of the endless belt via the spring member when the belt unit is mounted in the main unit of the image forming device.
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이 특허에 인용된 특허 (8)
Okiyama Yoshitatsu,JPX ; Kikuchi Ken,JPX, Belt unit.
Hayano Tomio (Hitachi JPX) Tsuruta Shizuo (Kitaibaraki JPX), Image forming apparatus with positioning member of frame engaging shaft of roller of photosensitive belt.
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