Printing up to edges of printing paper without platen soiling

Details Printing up to edges of printing paper without platen soiling Printing up to edges of printing paper without platen soiling

2001-09-26

2004-06-08

Meier, Stephen D. (Department: 2853)

Incremental printing of symbolic information

Ink jet

Ejector mechanism

C347S014000

Reexamination Certificate

active

06746101

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technique for recording dots on the surface of a recording medium with the aid of a dot-recording head, and more particularly to a technique for printing images up to the edges of printing paper without soiling the platen.
2. Description of the Related Art
Printers in which ink is ejected from the nozzles of a print head have recently become popular as computer output devices.
FIG. 24
is a side view depicting the periphery of a print head for a conventional printer. Printing paper P is supported on a platen
26
o
while facing the head
28
o
. The printing paper P is fed in the direction of arrow A by the upstream paper feed rollers
25
p
and
25
q
disposed upstream of the platen
26
o
and by the downstream paper peed rollers
25
r
and
25
s
disposed downstream of the platen
26
o
. Dots are recorded and images printed on the printing paper P when ink is ejected from the head.
SUMMARY OF THE INVENTION
When an attempt is made to print images without blank spaces up to the edges of printing paper with the aid of such a printer, it is necessary to arrange the printing paper such that the edges of the printing paper are disposed underneath the print head (that is, on the platen) and to cause ink droplets to be ejected from the print head when print data are specified for the areas that extend up to the edges of the printing paper and printing is carried out. With such printing, however, blank spaces form in the edge portions of the printing paper due to errors developing during the feeding of the printing paper, a shift in the impact location of the ink droplets, or the like. In addition, the ink droplets sometimes miss the edges of the printing paper (for which the droplets have been originally intended) and end up depositing on the platen due to errors developing during the feeding of the printing paper, a shift in the impact location of the ink droplets, or the like. In such cases, the ink deposited on the platen soils the printing paper transported over the platen in the next step.
It is an object of the present invention, which was perfected in order to overcome the above-described shortcomings of the prior art, to provide a technique that allows images to be printed up to the edges of printing paper while preventing ink droplets from depositing on the platen.
Perfected in order to at least partially overcome the above-described shortcomings, the present invention envisages performing specific procedures for a dot-recording device designed to record dots on the surface of a print medium with the aid of a dot-recording head provided with a plurality of dot-forming elements for ejecting ink droplets. This dot-recording device comprising a main scanning unit configured to drive the dot-recording head and/or the print medium to perform main scanning, a head driver configured to drive at least some of the dot-forming elements to form dots during the main scanning, a platen configured to extend in the main scanning direction and to be disposed opposite the dot-forming elements at least along part of a main scan path, a sub-scanning unit configured to move the print medium to perform sub-scanning in between the main scans, and a controller configured to control the dot-recording device.
The platen has a slot configured to extend in the main scanning direction, a width of the slot in the sub-scanning direction corresponding to a specific sub-scanning range on a surface of the dot recording head including at least part of the plurality of dot-forming elements.
In the printing, an expanded area is set in accordance with a type of print medium to be used in the dot recording, the expanded area extending lengthwise beyond at least front and rear edges of the print medium, and representing a recording area in which images are to be recorded on the print medium. Print data for recording images in the expanded area is prepared. Then edge printing is performed by ejecting ink droplets from at least some of the dot-forming elements disposed opposite the slot when images are printed at least in front- or rear-edge portions of the print medium on the basis of the print data.
With this arrangement, ink droplets can be prevented from depositing on the platen, and images can be printed without blank spaces up to the front and rear edge of the print medium. Selecting the correct size for the expanded area in accordance with the type of print medium makes it possible to prevent situations in which time is wasted when images are printed by ejecting ink droplets over an area that is unnecessarily wide for a given size of print medium.
The type of print medium preferably depends on dimensions of the print medium. When a print medium tilts away from its intended orientation, the extent to which the edge portions of the print medium are shifted increases with the dimensions of the print medium. Consequently, selecting an expanded area in accordance with a category related to the dimensions of the print medium makes it possible to establish the expanded area in an appropriate manner such that ink droplets are prevented from depositing on the platen, and images are printed without blank spaces up to the edges of the printing paper.
The type of print medium should preferably be set in accordance with the material of the print medium. The feed error occurring during the sub-scanning of a print medium sometimes varies with the type of print medium. Consequently, selecting an expanded area in accordance with a category related to the material of the print medium makes it possible to establish the expanded area in an appropriate manner such that ink droplets are prevented from depositing on the platen, and images are printed without blank spaces up to the edges of the printing paper.
The following procedure should preferably be adopted when ink droplets are ejected onto an expanded area. When ink droplets are ejected onto the front edge of the print medium, the position of the print medium in the sub-scanning direction is set such that the print medium is supported on the platen, the front edge of the print medium is brought to a point above the slot, and the front edge of the print medium reaches a point located in the sub-scanning direction upstream of a dot-forming element at a downstream end in the sub-scanning direction. When ink droplets are ejected onto the rear edge of the print medium, the position of the print medium in the sub-scanning direction is set such that the print medium is supported on the platen, the rear edge of the print medium is brought to a point above the slot, and the rear edge of the print medium reaches a point located in the sub-scanning direction downstream of a dot-forming element at an upstream end in the sub-scanning direction. With this arrangement, ink droplets can be prevented from depositing on the platen, and images can be printed without blank spaces up to the front and rear edge of the print medium.
The following procedure should preferably be adopted during the preparation of print data when the platen has a pair of lateral slots that are separated apart at a distance substantially equal to the width of the print medium, and the lateral slots extend in a sub-scanning range in which ink droplets are ejected from the plurality of dot-forming elements. The print data for recording images in an expanded area is prepared. The expanded area extends widthwise beyond left and right edges of the print medium but remaining between farthermost side walls of the pair of lateral slots. With this arrangement, it is possible to prepare print data whereby ink droplets can be prevented from depositing on the platen, and images can be printed without blank spaces up to the left and right edges of the print medium.
The following procedure should preferably be adopted when ink droplets are ejected onto the expanded area. The position of the print medium in the main scanning direction is set such that the print medium is supported on the platen, and the left and right edges of the print medium

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