Patent Application
20060146106
1. Field of the Invention
The present invention relates generally to an inkjet carriage unit and an image forming apparatus, such as an inkjet recording apparatus, using the same.
2. Description of the Related Art
Image forming apparatuses such as inkjet recording apparatuses have a scanning part that causes a carriage having recording heads mounted thereon to scan paper in a predetermined scanning direction while guiding the carriage with a guide rod. The recording heads are driven based on image data during scanning by the carriage so that an image is formed. In general, these inkjet recording apparatuses includes a linear scale bearing marks for detecting the position of printing heads, and a read sensor to read the marks while moving along the linear scale. The linear scale is shaped like an elongated film extending in the scanning direction of the carriage. Its marks are provided at very narrow intervals (for example, 0.084 mm in the case of 300 dpi) (see, for example, Japanese Patent No. 2958131).
In image forming apparatuses such as inkjet recording apparatuses as described above, various modifications such as making many component parts and members replaceable are made so as to make apparatus service life much longer, for example, tenfold. In this respect, there is a need to remove and replace a carriage or replace a light emission part and a light reception part forming an encoder sensor. This is because longer apparatus service life may cause contamination of the encoder sensor, specifically, its light emission part and light reception part, with ink mist, thus causing a problem in that position detection cannot be performed with accuracy.
In order to perform such replacement, first, it is necessary to remove the carriage from a guide rod. In this case, the conventional structure also requires the linear scale to be removed. However, since the marks of the linear scale are arranged at very fine intervals, an operator is prevented from touching the marks with her/his hand. This is because the sebum of the hand adheres to the marks of the linear scale through touching them so as to prevent the marks from being read. Therefore, according to the conventional structure, it is almost impossible to actually remove and replace the carriage.
Accordingly, it is a general object of the present invention to provide an inkjet carriage unit in which the above-described disadvantage is eliminated.
A more specific object of the present invention is to provide an inkjet carriage unit in which it is possible to replace a carriage or an encoder sensor without removing a linear scale so that an operator can work without the fear of touching the linear scale.
Another more specific object of the present invention is to provide an inkjet recording apparatus and an image forming apparatus employing such an inkjet carriage unit.
One or more of the above objects of the present invention are achieved by an inkjet carriage unit including a main body, a sensor holding part detachably attached to the main body, and an encoder sensor attached to the sensor holding part.
According to one aspect of the present invention, a carriage and an encoder sensor can be replaced without removing a linear scale. As a result, an operator is less likely to touch the linear scale with her/his hand.
One or more of the above objects of the present invention are also achieved by an inkjet recording apparatus including an inkjet carriage unit according to one embodiment of the present invention.
One or more of the above objects of the present invention are also achieved by an image forming apparatus including an inkjet carriage unit according to one embodiment of the present invention.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings, in which:
A description is given below, with reference to the accompanying drawings, of embodiments of the present invention.
The print mechanism part 2 holds the carriage 13 with a main guide rod 11 so that the carriage 13 is slidable in the main scanning directions. The main guide rod 11 is provided between Y1-side and Y2-side side plates (not graphically illustrated). The recording head 14 including inkjet heads ejecting ink droplets of respective colors of yellow (Y), cyan (C), magenta (M), and black (Bk) is attached to this carriage 13 so that the ink droplets are ejected downward (in the Z2 direction). The sub tanks 12 for supplying color inks to the recording head 14 are attached to an upper part of the carriage 13.
Each sub tank 12 is connected through an ink supply tube 16 to a corresponding one of replaceably attached ink tanks 15, so that a corresponding one of the color inks is supplied therefrom to the sub tank 12. The main guide rod 11 passes through an X1-side part of the carriage 13 (a upstream-side part of the carriage 13 in the paper conveyance direction) so that the carriage 13 is slidable on the main guide rod 11. In order to cause the carriage 13 to move and scan in the main scanning directions, a timing belt 20 is engaged with a drive pulley 18 rotated by a main scanning motor 17 and a driven pulley 19 so as to be stretched therebetween, and the timing belt 20 is fixed to the carriage 13.
On the other hand, in order to convey the paper 3 set in the paper feed cassette 4 to the lower (Z2) side of the recording head 14, a paper feed roller 21 and a friction pad 22 to separate and feed the paper 3 from the paper feed cassette 4, a guide member 23 to guide the paper 3, a conveyance roller 24 to convey the fed paper 3 in a reversed position (upside down), a conveyance roller 25 to be pressed against the cylindrical surface of the conveyance roller 24, and an edge roller 26 to determine an angle at which the paper 3 is fed out from the conveyance roller 24 are provided. The conveyance roller 24 is rotated by a sub scanning motor 27 through a gear train.
An electrostatic conveyor belt 29 to guide the paper 3 fed from the conveyance roller 24 below the recording head 14 is provided in correspondence to the range of movement of the carriage 13 in the main scanning directions. The electrostatic conveyor belt 29 is charged by a charger 30 so as to attract the conveyed paper 3 so that the paper 3 adheres to the electrostatic conveyor belt 29, thereby keeping the surface of the paper 3 and the surface of the recording head 14 in parallel with each other. A paper output roller 33 to send out the paper 3 onto the paper output tray 6 is provided on the downstream side of the electrostatic conveyor belt 29 in the paper conveyance direction.
If necessary, a paper reversing unit 8 and a paper feed unit 9 may be attached to the main body 1 as shown in
As graphically illustrated, the carriage 13 includes the sensor holding member 50 for holding an encoder sensor 40. The sensor holding member 50 is provided at a position obliquely upward from an insertion part 13A through which the main guide rod 11 passes. That is, the sensor holding member 50 is provided at a position above and offset at an angle from the insertion part 13A. The sensor holding member 50 is attachable and detachable (removable) in the vertical directions (or along the Z-axis indicated by the double-headed arrow in
The sensor holding member 50 includes a holding part 53 that can pass through the opening 51 and a base plate part 54 that does not pass through the opening 51, and is formed into a T letter shape. The encoder sensor 40 is held by the holding part 53, being attached to the vicinity of a lower end of the holding part 53. It is desirable that the encoder sensor 40 be detachable from and reattachable to the holding part 53. The encoder sensor 40 includes a groove part 42 through which a linear scale 41 passes. A light emission part 43 is provided on one side and a light reception part 44 is provided on the other side on the interior surface of the groove part 42 so as to read the marks of the linear scale 41 as described above, thereby detecting the position of the carriage 13. The positions of the light emission part 43 and the light reception part 44 shown in
A guide part 55 is provided on the lower end of the sensor holding member 50 so as to protrude therefrom in such a manner as to receive the encoder sensor 40. The lower end surface of the guide part 55 is formed like a slope that is lower on the side of the main body 13a of the carriage 13 and higher on the side of the encoder sensor 40. As a result, even if the slope (lower end surface) of the guide part 55 comes into contact with the linear scale 41 in attaching the sensor holding member 50, the slope serves as a slide guide and does not become a load on the linear scale 41. The linear scale 41 may have a tape-like shape.
That is, according to this embodiment, removal and replacement of the carriage 13 and removal and replacement of the encoder sensor 40 are performed by first releasing fixation of the base plate part 54 of the sensor holding member 50 to the attachment part 52 of the carriage 13, then pulling the entire body of the sensor holding member 50 upward, and extracting the holding member 53 through the opening 51. If a configuration does not allow the encoder sensor 40 to pass through the opening 51, the encoder sensor 40 may be detached from the holding part 53 with the sensor holding member 50 being pulled halfway up. As a result, it is possible to extract the main guide rod 11 and remove the carriage 13 without the possibility of touching the linear scale 41. Even if the main guide rod 11 or the carriage 13 comes into contact with the linear scale 41 during this operation, there is hardly any problem. Further, the carriage 13 and the encoder sensor 40 may be attached in the opposite procedure to the one described above.
Further, in the first embodiment, the sensor holding member 50 is detachable from and reattachable to the main body 13a of the carriage 13 in the vertical directions. Alternatively, as shown in
Thus, according to one aspect of the present invention, a carriage and an encoder sensor can be replaced without removing a linear scale. As a result, an operator is less likely to touch the linear scale with her/his hand.
The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention.
The present application is based on Japanese Priority Patent Application No. 2005-000422, filed on Jan. 5, 2005, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-000422 | Jan 2005 | JP | national |
