Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
1998-05-11
2001-09-18
Grimley, Arthur T. (Department: 2852)
Incremental printing of symbolic information
Ink jet
Medium and processing means
Reexamination Certificate
active
06290350
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus such as a printer, a copying machine and the like. More particularly, it relates to an image forming apparatus in which a sheet is discharged onto a discharge portion after the sheet is temporarily held.
2. Related Background Art
In conventional image forming apparatuses, generally, a sheet on which an image is recorded by a recording means is discharged onto a discharge portion immediately after recording. Such an arrangement has widely been used in image forming apparatuses of the ink jet recording system which have recently been popularized.
In the ink jet recording system, the recording is effected by discharging ink droplets. Regarding recording density of normal recording such as a standard document or a table, there is no problem, but, when recording density is great (such as color recording), a time period sufficient to fix the ink is required. In a color image forming apparatus, if an image forming speed is increased, before the ink is fixed to the sheet discharged on the discharge portion, a next sheet is discharged onto a discharge portion. As the result, the imaged surface of the preceding sheet discharged on the discharge portion is rubbed by a tip end or a back surface of the next sheet, thereby distorting the recorded image.
To avoid this problem, a technique for promoting the drying of ink by using heat from an infrared ray heater has been proposed. However, when the infrared ray heater is used, the entire apparatus is made complicated and expensive. Thus, a technique not using the heater has also been proposed.
For example, as shown in
FIG. 11
, a pair of opposed and spaced side rail members
50
a,
50
b
are supported for rotation around respective pivot points
51
a,
51
b.
Further, vertical walls
52
a,
52
b
are provided with recessed portions
53
a,
53
b
through which the side rail members
50
a,
50
b
are rotated in directions shown by the arrows X.
With the arrangement as mentioned above, a recorded sheet S is conveyed by a convey means (not shown) in a direction perpendicular to the plane of FIG.
11
.
At this point, as shown in
FIG. 11
, the side rail members
50
a,
50
b
are held in a closed position so that they can support the sheet S and hold the sheet above a discharge portion
54
a
of a discharge tray
54
. When the sheet S is discharged, the side rail members
50
a,
50
b
are rotated in the directions X to an open position where the side rail members do not interfere with the sheet S, thereby permitting the dropping of the sheet onto the discharge portion
54
a.
In this way, the ink image recorded on the sheet S rested on the discharge portion
54
a
is dried while the image is being recorded on the succeeding sheet, thereby preventing deterioration of the recorded image.
However, in the above-mentioned technique, since the operation of the side rails must be synchronized with the sheet conveying operation, the mechanism may be made complicated. And, if a drive source such as a motor for achieving the synchronism is added, the entire apparatus will be made more expensive.
SUMMARY OF THE INVENTION
The present invention aims to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide an image forming apparatus in which ink contamination and distortion of an imaged surface of a discharged sheet can be prevented with a simple construction, without worsening sheet discharging and stacking ability and without making an entire apparatus bulky and expensive.
To achieve the above object, there is provided an image forming apparatus comprising a recording means adapted to record an image on a sheet and having a carriage for shifting the recording means in a sheet width-wise direction, a convey rotary means for conveying the sheet through the recording means and for discharging the sheet after recording, a support means for supporting one surface of the sheet, and a shift means for shifting the support means between a support position where the sheet is supported above a discharge portion and a retard position where the sheet is not supported by the support means. The shift means is switched in accordance with a position of the carriage and has a transmission means for effecting ON/OFF of a driving force for rotating the convey rotary means.
With the arrangement as mentioned above, by supporting the discharged sheet by means of the support means, a succeeding sheet being discharged can be prevented from rubbing a recorded surface of a preceding sheet already discharged on the discharge portion, thereby preventing ink contamination and distortion of the recorded image.
Further, by shifting the support means by the shifting movement of the carriage and the drive source for sheet conveyance, the sheet can be supported and released with a simple construction, without adding any new drive source.
REFERENCES:
patent: 4794859 (1989-01-01), Huseby et al.
patent: 4844633 (1989-07-01), Greenberg
patent: 5226743 (1993-07-01), Jackson et al.
patent: 5536000 (1996-07-01), Kelly
patent: 5603493 (1997-02-01), Kelly
patent: 5927877 (1999-07-01), Kelly et al.
patent: 0 530 821 (1993-03-01), None
patent: 0 792 751 (1997-09-01), None
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Grimley Arthur T.
Ngo Hoang
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