1. A medium transportation apparatus, comprising:
a transportation portion for transporting a medium;
a first structure unit for forming a first transportation path to guide and transport the medium in a first direction from an upstream side in a medium transportation direction toward a downstream side in the medium transportation direction; and
a second structure unit for forming an accommodation space to accommodate a part of the first structure unit,
wherein said first structure unit includes a first region disposed outside the accommodation space on the downstream side in the medium transportation direction and a second region disposed inside the accommodation space on the upstream side in the medium transportation direction
2. The medium transportation apparatus according to claim 1, wherein said second structure unit is configured to form a second transportation path to guide the medium in a direction inclined relative to the first direction toward the first transportation path, and
said first structure unit includes a receiving surface that a leading edge of the medium abuts against when the medium is transported from the second transportation path toward the first transportation path.
3. The medium transportation apparatus according to claim 2, wherein said second structure unit includes a surface forming the second transportation path and being curved downwardly in a range from the transportation portion to the receiving surface of the first structure unit, and
said accommodation space is situated below the second transportation path in a vertical direction with the surface forming the second transportation path being as a horizontal plane.
4. The medium transportation apparatus according to claim 3, wherein said second structure unit includes a surface forming the second transportation path and having a substantially C-character sectional shape taken along an imaginary plane in parallel to the first direction and the vertical direction, and
said accommodation space is situated near and below a top portion of the surface forming the second transportation path in the vertical direction.
5. The medium transportation apparatus according to claim 1, wherein said first structure unit includes at least one roller holding portion capable of holding a roller to be freely rotatable, and
said roller holding portion does not hold the roller when the roller holding portion is situated in the second region.
6. The medium transportation apparatus according to claim 1, wherein said first structure unit is configured as a separate unit from the second structure unit, and
said first structure unit is arranged adjacent to the second structure unit.
7. The medium transportation apparatus according to claim 1, wherein said first structure unit is arranged on the downstream side of the second transportation path of the second structure unit in the medium transportation direction, and
said accommodation space is arranged on the downstream side of the second transportation path in the medium transportation direction.
8. The medium transportation apparatus according to claim 1, wherein said first structure unit is arranged so that an end portion thereof on the upstream side in the medium transportation direction is accommodated in the accommodation space.
9. An image forming apparatus comprising the medium transportation apparatus according to claim 1.
10. An image forming apparatus, comprising:
the medium transportation apparatus according to claim 1;
an image forming portion for forming an image on the medium; and
a medium reverse transportation portion for reversing the medium after the medium passes through the image forming portion, and for returning the medium to the image forming portion.
11. The image forming apparatus according to claim 9, wherein said second region has a first length in the first direction when the image forming apparatus is a monochrome image forming apparatus, and
said first length is greater than a second length of the second region of the image forming apparatus that is a color image forming apparatus.
12. The image forming apparatus according to claim 10, further including a plate member arranged to face the first structure unit,
wherein said plate member has a first length when the image forming apparatus is a monochrome image forming apparatus,
said plate member has a second length greater than the first length when the image forming apparatus is a color image forming apparatus,
said image forming portion includes one image forming unit when the image forming apparatus is the monochrome image forming apparatus, and
said image forming portion includes a plurality of image forming units when the image forming apparatus is the color image forming apparatus.
13. A structure unit for forming a transportation path to guide and transport a medium to be printed from an upstream side in a medium transportation direction toward a downstream side in the medium transportation direction, comprising:
a first region disposed outside an accommodation space on the downstream side in the medium transportation direction when the structure unit is attached to a first apparatus; and
a second region disposed inside the accommodation space on the upstream side in the medium transportation direction when the structure unit is attached to the first apparatus,
wherein said second region has a first length when the structure unit is attached to a first apparatus, and
said second region has a second length shorter than the first length when the structure unit is attached to a second apparatus.
14. The structure unit according to claim 13, further comprising at least one roller holding portion situated in the second region and capable of holding a roller to be freely rotatable,
wherein said roller holding portion does not hold the roller when the structure unit is attached to the first apparatus, and
said roller holding portion holds the roller when the structure unit is attached to the second apparatus.
15. A method of assembling a medium transportation apparatus inside an image forming apparatus, said medium transportation apparatus including a transportation portion for transporting a medium; a first structure unit for forming a first transportation path to guide and transport the medium in a first direction from an upstream side in a medium transportation direction toward a downstream side in the medium transportation direction; and a second structure unit for forming an accommodation space to accommodate a part of the first structure unit,
said method comprising the steps of:
attaching the second structure unit to a main body structure portion of the image forming apparatus so that the accommodation space is formed;
placing the first structure unit so that the first structure unit includes a first region disposed outside the accommodation space on the downstream side in the medium transportation direction and a second region disposed inside the accommodation space on the upstream side in the medium transportation direction;
adjusting a length of the second region in the first direction to set a transportation path length of the first region; and
attaching the first structure unit to the main body structure portion of the image forming apparatus.
16. The method of assembling the image forming apparatus according to claim 14, wherein said second region has a first length in the first direction when the image forming apparatus is a monochrome image forming apparatus, and
said first length is greater than a second length of the second region of the image forming apparatus that is a color image forming apparatus.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A rotational facility comprising:
a driving device,
a barrel coupled to said driving device for being rotated and driven by said driving device,
a wheel rotatably attached onto said barrel, and
a braking device secured to said wheel for engaging with said barrel and for braking said wheel relative to said barrel.
2. The rotational facility as claimed in claim 1, wherein said wheel includes at least one unidirectional bearing engaged between said wheel and said barrel to allow said wheel to be rotated relative to said barrel in one direction.
3. The rotational facility as claimed in claim 1, wherein said braking device includes a housing secured to said wheel and having a bore formed therein for rotatably attached onto said barrel, and includes at least one actuating member received in said housing and extended into said bore of said housing to engage with said barrel and to brake said housing and said wheel relative to said barrel.
4. The rotational facility as claimed in claim 3, wherein said housing includes a brake member received therein for engaging with said at least one actuating member and for actuating said at least one actuating member to engage with said barrel.
5. The rotational facility as claimed in claim 4, wherein said housing includes a peripheral channel formed therein and defined by an inner peripheral wall and an outer peripheral wall for receiving said brake member therein.
6. The rotational facility as claimed in claim 5, wherein said brake member includes a bore formed therein and defined by an inner peripheral surface for rotatably attached onto said inner peripheral wall of said housing, and includes at least one braking element extended into said bore thereof for engaging with and for actuating said at least one actuating member to engage with said barrel.
7. The rotational facility as claimed in claim 6, wherein said housing includes a spring member engaged with said brake member for biasing said at least one braking element to actuate said at least one actuating member to engage with said barrel.
8. The rotational facility as claimed in claim 7, wherein said housing includes an adjusting device for engaging with said spring member and for adjusting an engagement between said brake member and said at least one actuating member and said barrel.
9. The rotational facility as claimed in claim 8, wherein said adjusting device includes a fastener secured to said housing and engaged with said spring member for adjusting said spring member relative to said housing.
10. The rotational facility as claimed in claim 9, wherein said housing includes an anchor member disposed therein and engaged between said fastener and said spring member.
11. The rotational facility as claimed in claim 7, wherein said brake member includes an extension extended therefrom for engaging with said spring member.
12. The rotational facility as claimed in claim 11, wherein said housing includes a compartment formed therein for receiving said extension of said brake member.