Patent Grant
6909447
1. Field of the Invention
The present invention relates to a recording apparatus provided for facsimile equipment, a copying machine, a printer, and the like. More particularly, the invention relates to the structure that drives discharging rollers of a recording sheet for the recording apparatus.
2. Related Background Art
Here, the driving force (or driving power) or of a motor 14 is transmitted to the conveying roller 13. Further, the first discharging roller 16 and the second discharging roller 17 are fixed to a platen (not shown). Then, the driving force is transmitted to the first discharging roller 16 and the second discharging roller 17 from the carrier gear 13a provided for one end of the conveying roller 13 through transmission gears 21 and 22.
In the structure shown in
Conventionally, there has been a difference in the conveyance precision between the area where the recording sheet is conveyed by use of the conveying roller and the area where the recording sheet is conveyed by use of only the discharging roller. Conventionally, the text printing and graphic printing have been the main operations in outputting images, and the difference in such conveyance precision has not presented any serious problem. However, with the enhancement of image quality of a recording apparatus in recent years, there is intensified a tendency to record picture images up to the maximum recordable area of a recording sheet. Along with this tendency, it has been desired to improve the conveyance precision of a recording sheet in the area where the recording sheet is conveyed only by use of the discharging roller so as to make the difference in the sheet conveyance precision smaller between this area and the areas where the recording sheet is conveyed by the conveying roller.
However, in the conventional example described above, the discharging roller is arranged in a position far away from the driving source. As a result, the number of gears needed for transmitting driving force from the driving source to the discharging roller becomes larger inevitably. Under the such circumstances, particularly in the structure having a plurality of discharging rollers arranged in the sheet conveying direction, it has not been realized to obtain the feed precision sufficiently satisfactory for the discharging roller positioned on the outermost downstream side in the sheet conveying direction, whereas this feed precision dominantly determines the conveyance precision of a recording sheet by use of the discharging rollers.
It is an object of the present invention to provide a recording apparatus capable of forming images in good condition on the rear portion of a recording sheet by enhancing the conveyance precision only by use of discharging rollers without any significant cost increase for a recording apparatus provided with plural discharging rollers.
It is another object of the invention to provide a recording apparatus for recording on a recording sheet by recording means, which comprises: a conveying roller for conveying a recording sheet on the upstream side of recording means in the recording sheet conveying direction; plural discharging rollers for conveying a recording sheet on the downstream side of recording means in the recording sheet conveying direction; and a common driving source for driving the plural discharging rollers; and in which the driving force (or driving power) of the driving source is transmitted first to a discharging roller on the outermost downstream side in the recording sheet conveying direction.
Hereinafter, with reference to the accompanying drawings, the description will be made of the embodiments in accordance with the present invention.
First Embodiment
Here, with reference to
At first, the entire structure of the apparatus will be described. Then, the structure of a discharging roller for discharging a recording sheet will be described.
As shown in FIG. 1 and
Inside the cover, the recording apparatus main body is incorporated as shown in FIG. 3. In
Also, for this recording apparatus, a feeding unit 5 is provided, and a plurality of sheets P yet to be recorded is stacked in here, and a feed roller (not shown) rotates to separate sheets P one by one for feeding in accordance with a starting signal of recording. Then, by a conveying means formed by a conveying unit 6, which is structured by a conveying roller and a pinch roller, and a discharging unit 7, which is structured by a discharging roller and a spur, the recording sheet is conveyed through the recording area and discharged to the outside.
Also, in the recording area, a carriage unit 8 is provided as a recording means, and performs a designated recording on the sheet P, which is being conveyed. For the present embodiment, the so-called ink jet recording method of serial type, in which the recording head reciprocates in the direction intersecting with the direction of recording sheet conveyance, and records lines one by one. A carriage 8a is installed so as to reciprocate along a guide shaft 8b, and the recording head 11 and an ink tank 8c are mounted on this carriage 8a. Then, in synchronism with the movement of the carriage 8a, the recording head 11 ejects ink to record images on the sheet P conveyed to the recording area. In this respect, a recovery unit 9 is arranged on the end portion of the traveling area of the carriage 8a to face the recording head 11, which sucks ink from the recording head before the initiation of recording, on the way of recording, or the like or conducts pre-ejection so as to carry out recording without ink ejection failure.
Then, the recording sheet is discharged by use of the discharging unit 7 after recording, and as shown in
Here, the description of the present embodiment is made using the ink jet recording method of serial type as has been described above. However, the present invention is not necessarily limited thereto. The invention is equally applicable to the ink jet recording apparatus of full-line type in which recording is performed by the recording head provided with an orifice array having the same width as the width in the direction intersecting with the conveyance direction of recording sheet. Also, the invention is not necessarily limited to the ink jet recording method. The driving mechanism of the recording sheet discharging roller of the present invention is applicable to the thermal transfer method, the laser method, and so on.
Next, with reference to
The conveying unit 6 (
Also, the discharging unit 7 (
The tray 10 for receiving discharged sheets is arranged below the second discharging roller 17 so that it can stack a plurality of sheets P, each of which is discharged through the recording area.
In this respect, the conveying roller 13, the first discharging roller 16, and the second discharging roller 17 are substantially in the same height.
Next, the description will be made of the image recording operation of the recording apparatus thus structured.
The conveying roller 13 and the pinch roller 18 pinch and convey the sheet P, which is separated and fed by use of the feeding unit 5. Then, when the sheet P reaches the designated position of the platen 12 for image recording, the carriage 8 reciprocates by means of a carriage motor (not shown), and in accordance with signals from an electric circuit board (not shown), the recording head 11 discharges ink to the sheet P for recording images. Here, the discharging rollers 16 and 17 and the spur rollers 19 and 20 pinch the sheet P on the downstream side of the recording head 11 in the direction X of sheet conveyance, and the conveying roller 13 and the pinch roller 18 pinch the upstream side thereof to convey it for recording. Then, from the leading end to the trailing end of the sheet P, recording is made on the designated area. After that, the trailing end of the sheet P passes the conveying roller 13 and the pinch roller 18. Subsequently, only the discharging rollers 16 and 17 convey the sheet P. In this manner, it is possible for the recording head 11 to record up to the rear end limit of the sheet P.
Here, in accordance with the present embodiment, as shown in
As described above, for the first discharging roller 16, inexpensive materials and method of manufacture are used, while adopting the second discharging roller 17 with the prior consideration given to the precision thereof. In this way, it is made possible to provide a sheet conveyance structure having a good balance in the conveyance precision of a sheet P and the cost performance thereof.
Further, as shown in FIG. 4 and
With the structure thus arranged, the conveyance precision of the second discharging roller 17, which dominantly determines the conveyance precision at the time of trailing end recording, is made highest among plural discharging rollers arranged side by side in the sheet conveying direction. In a case where plural discharging rollers are driven by one driving source, there exist inclusively other discharging roller gears between the driving source and the discharging roller so that the driving force is transmitted. In the structure of the present embodiment, it is arranged to transmit at the beginning the driving force from the driving source to the second discharging roller 17, which needs the highest conveyance precision, thereby significantly enhancing the conveyance precision at the time of recording on the trailing end portion of the sheet. This is because if the number of gears on the way is increased, there are inevitably influences exerted by the part precisions, such eccentricity of gears. Also, the accumulated amount of backlashes of gears causes unstable conveyance precision. The structure of the present embodiment, however, makes it possible to minimize them.
Also, the conveying roller 13 and the second discharging roller 17 share the driving source of one motor for use, and the sheet conveyance precision is improved reliably without const increase from that of the conventional structure.
Here, the motor 14 is arranged of necessity between the conveying roller 13 and the second discharging roller 17, and the motor 14 can be contained in the discharging unit, too. Consequently, it is possible to save the required space by the portion corresponding to the motor space as compared with the conventional structure (FIG. 9), in which the motor 14 is arranged on the upstream side of the main conveying roller 13 in the direction X of sheet conveyance.
Also, as shown in
In this respect, as shown in
Here, in conjunction with
As described earlier, the trailing end of a sheet P is conveyed by two discharging rollers 16 and 17 after it has passed the conveying roller 13, and the recording head 11 ejects ink to perform recording. As shown in
In this state, the force is exerted on the trailing end of the sheet P in the direction in which such portion tends to float centering on the tangential line 17a of the second discharging roller 17 and the spur 20. This force is generated by the own weight of the sheet P and the firmness thereof. The spur 19 functions to keep the sheet P in good conveying condition by resisting such floating force to keep a distance between the sheet P and the ink ejection surface of the recording head 11. However, the pressure of the spur 19 to the first discharging roller 16 is reduced because the spur should provide resistance to the floating force. On the other hand, the sheet P is in contact with the second discharging roller 17 as it wraps in the circumferential direction of the roller by the own weight of the sheet P. Therefore, the conveying force of the second discharging roller 17 against the sheet P is extremely large, with the result that the ratio of influence exerted on the conveyance precision of the sheet P by the second discharging roller 17 becomes significantly large.
Now, as has been described above, it is reasonable to form the structure so as to arrange in high precision the discharging roller on the outermost downstream side, which has the greatest conveying force for the sheet P owning to the phenomenon of the kind.
In this respect, the spurs 19 and 20 are arranged to face each of the roller portions 16d and 17d, respectively, and arranged to give pressure of as comparatively small as 10 gf to each of the roller members by use of spring members (not shown). This arrangement is made so as to prevent the surface of the sheet P, on which images are recorded, from being spoiled, and keep images in good condition.
Table 1 shows the data obtained from the experiments for determining the structure hereof.
The precision of discharging roller on downstream side (1):
As understandable from the Table 1, the combination of discharging rollers on the upstream side and downstream side, the precisions of which are both enhanced, indicate the best result of±12 μm at 3 σ as a matter of course. However, only the precision of the discharging roller on the downstream side is enhanced as disclosed in the present embodiment makes it possible to secure±15 μm, which is the precision at almost the same level as the best result.
This has a great difference as compared with the result of±35 μm indicated by the combination of (2) and (3) where roller precision is attempted on the upstream side, and obviously, it is most effective to make the precision higher only for the discharging roller on the downstream side. Then, further, the driving force is transmitted earlier (or firstly) for the discharging roller on the outermost downstream, which is dominant with respect to the conveyance precision provided by a plurality of discharging roller lines, than other discharging rollers, whereby the influences that may be exerted by the eccentricity of gears and backlashes thereof can be minimized to make it possible to effectuate the sheet conveyance in high precision by use of a plurality of discharging roller lines.
In this respect, the “3 σ” is a value obtainable by multiplying the standard deviation σ by 3, and when a large-scale production is attempted, it is estimated that the ratio of good products arrives at 99.73% (within the numerical value of 3 σ). For that matter, this is a numerical value that serves as a target when products inspection is carried out.
As described above, in accordance with the present embodiment, there are provided the discharging roller 16, 17 and others for discharging the sheet P, and the motor 14 drives all the discharging rollers. In this structure, the driving force is provided first for the discharging roller 17 on the outermost downstream side in the direction of sheet conveyance, hence making it possible to enhance the conveyance precision when the sheet is conveyed only by plural discharging roller lines so as to provide printed images in good condition on the rear portion of the recording sheet P. Further, the motor 14, which is the driving source of the discharging rollers 16 and 17, is shared as a driving source for the conveying roller 13 that conveys the recording sheet to the recording area. In this way, it is made possible to attempt the enhancement of conveyance precision only by use of plural discharging rollers without any cost increase as compared with the conventional structure.
Also, a space saving is possible by arranging the motor 14 that serves as the driving source described earlier between the discharging roller 17 on the outermost downstream side in the direction of sheet conveyance and the conveying roller 13.
Also, the driving source of the discharging roller 17 on the outermost downstream side in the direction of recording sheet conveyance and the conveying roller 13 is directly connected for driving without intervention of the intermediate transmission gears 21, 22, and the like. With this arrangement, it becomes possible to attempt further the enhancement of sheet conveyance precision only by use of discharging roller, thus providing printed images in good condition on the rear portion of a recording sheet.
In this respect, the numerical values, materials, and the like are described in the present embodiment as example, and such numerical values, materials, and the like are not necessarily limited thereto.
Also, the discharging rollers are not necessarily limited to two rollers. The same effect is equally obtainable when discharging rollers are used in plural numbers more than two.
Second Embodiment
In accordance with the first embodiment described above, gears are used as driving force transmission means from the motor 14 to each of the rollers, but as shown in
In
With the driving force transmission by use of belts, the backlash that occurs in use of gear driving is eliminated. Therefore, it becomes possible to materialize a higher precision of sheet conveyance than the first embodiment.
In this respect, the driving force transmission to the first discharging roller 16 is conducted through the output gear 17e of the second discharging roller 17, the transmission gear 21, and the first discharging roller gear portion 16b as shown in
In accordance with the mode thus arranged, the driving force transmission to the discharging roller 17 on the outermost downstream side in the direction of sheet conveyance is effectuated using the belt 30 to make it possible to enhance more the conveyance precision of sheet only by use of the discharging rollers, thus providing printed images in good condition on the rear portion of a recording head.
As described above, in accordance with the present embodiment, a recording apparatus, in which a plurality of discharging roller for discharging a recording sheet is provided in the direction of recording sheet conveyance, and then, with one driving source, the plural discharging rollers are driven, transmits the driving force first to the discharging roller on the outermost downstream side in the direction of recording sheet conveyance. In this way, the conveyance precision is enhance when the recording sheet is conveyed only by use of discharging rollers, thus making it possible to provide printed images in good condition on the rear end portion of the recording sheet. Further, the driving source of the aforesaid plural discharging rollers is shared for use as the driving source for the conveying roller that conveys a recording sheet to the recording area, whereby it becomes possible to attempt the enhancement of the sheet conveyance precision by use of only discharging rollers without any increase of cost as compared with the conventional structure.
Also, a space saving is attempted by arranging the aforesaid driving source between the discharging roller on the outmost downstream side in the direction of a recording sheet conveyance and the aforesaid conveying roller.
Also, the driving source of the conveying roller and the discharging roller on the outermost downstream side in the direction of recording sheet conveyance are directly connected without any intervention of intermediate driving force transmission means. In this way, it is possible to enhance more the sheet conveyance precision only by use of discharging rollers, hence providing printed images in good condition on the rear end portion of a recording sheet.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2001-243503 | Aug 2001 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5166883 | Gilham | Nov 1992 | A |
| 5725206 | Sugiyama | Mar 1998 | A |
| 5775823 | Bekki et al. | Jul 1998 | A |
| 5813783 | Takatori | Sep 1998 | A |
| 5982400 | Yokoi et al. | Nov 1999 | A |
| 6092893 | Yokoi et al. | Jul 2000 | A |
| 6106114 | Sugiyama | Aug 2000 | A |
| 6170817 | Kawaguchi | Jan 2001 | B1 |
| 6217143 | Munakata et al. | Apr 2001 | B1 |
| 6328394 | Shirai et al. | Dec 2001 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20030030712 A1 | Feb 2003 | US |
