Image-recording apparatus

Details Image-recording apparatus Image-recording apparatus

2002-09-03

2004-04-06

Nguyen, Thinh (Department: 2853)

Incremental printing of symbolic information

Ink jet

Ejector mechanism

C347S040000

Reexamination Certificate

active

06715856

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-266246, filed Sep. 3, 2001, the entire content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image-recording apparatus which ejects ink to a recording-medium and records an image.
2. Description of the Related Art
Image-recording apparatuses such as an ink jet printer, ejects ink to recording media such as paper and a records an image. The image-recording apparatus comprises a recording-head for discharging ink to the recording-medium; a carriage for holding the recording-head; conveying means for conveying the recording-medium; and carriage-driving mechanism for moving the recording-head in a direction (main scanning direction) crossing at right angles to a conveying direction (sub scanning direction) of the recording-medium by the conveying means.
In the image-recording apparatus, the carriage is driven along the main scanning direction. When the carriage is driven, the recording-head is moved along the main scanning direction. During the movement, the recording-head ejects ink drops to the recording-medium. Thereby, the image-recording apparatus puts the ink drops to the recording-medium at substantially constant pitches along the main scanning direction. Thereby, the image-recording apparatus records an image corresponding to a width of the recording-head in the recording-medium. The image-recording apparatus repeats the above-described recording on the recording-medium intermittent conveyed along the sub scanning direction. The image-recording apparatus repeats the recording to record the whole image in the recording-medium.
A conventional image-recording apparatus will be described hereinafter.
FIG. 12
is a side view showing the conventional image-recording apparatus. In the image-recording apparatus, as shown in
FIG. 12
, carriage-driving mechanism
110
includes a pair of pulleys
111
, endless belt
112
, motor
113
, and carriage support portion
114
. Moreover, the carriage is denoted with a reference numeral
120
in FIG.
12
. The carriage
120
has a recording-head. Additionally, in
FIG. 12
, the sub scanning direction is a direction extending along an arrow AS. The main scanning direction extends along an arrow AM.
A pair of pulleys
111
are disposed apart from each other along the main scanning direction. An image-recording area ZP and two reverse areas ZR are disposed between the pair of pulleys
111
. The image is recorded to a recording-medium
200
in the image-recording area ZP. A width of the image-recording area ZP along the main scanning direction is set to be substantially the same as or slightly larger than the width of the recording-medium
200
. In the reverse areas ZR, the movement direction of the carriage
120
moved along the main scanning direction is reversed. The reverse areas ZR will be described in more detail. The carriage
120
moves in the image-recording area ZP. When the carriage
120
moves beyond the image-recording area ZP, the carriage
120
changes its moving-direction (turns about) toward the image-recording area ZP again. That is, the carriage changes its moving-direction in the reverse areas ZR. Therefore, the reverse areas ZR are disposed near the respective pulleys
111
. In other words, the reverse areas ZR are disposed on the opposite sides via the image-recording area ZP between the pair of pulleys
111
.
The endless belt
112
is supported by the pair of pulleys
111
.
The motor
113
is connected to one of the pair of pulleys
111
. The motor
113
supplies its driving force to the pulleys
111
.
The carriage support portion
114
is fixed to the endless belt
112
, and supports the carriage
120
. That is, the carriage
120
is fixed to the endless belt
112
via the carriage support portion
114
.
The carriage-driving mechanism
110
is driven by the motor
113
to operate the endless belt
112
supported by the pulleys
111
. The carriage
120
can be reciprocated along the main scanning direction by the action of the endless belt
112
. Therefore, the carriage-driving mechanism
110
can reciprocate the recording-head fixed to the carriage
120
along the main scanning direction.
There is an image-recording apparatus of a reciprocating print type. The reciprocating print type is an image recording system for discharging ink in both forward and backward movements during the reciprocating movement of the recording-head, and recording the image. Moreover, the image-recording apparatus has various types of arrangement of the recording-head. For example, as described in Jpn. Pat. Appln. KOKAI Publication No. 1998-250058, there is also an image-recording apparatus in which a plurality of recording-heads are arranged along the main scanning direction.
In the above-described image-recording apparatus, while the recording-head is moved, the ink is ejected. Therefore, in the image-recording apparatus, in order to record a high-quality image, it is preferable to move the recording-heads constantly at a constant speed in the image-recording area ZP. For this, the carriage-driving mechanism
110
needs to include the pulleys
111
and motor
113
which completely have no eccentricity. That is, the carriage-driving mechanism
110
in an ideal state includes the pulleys
111
and motor
113
which completely have no eccentricity. However, in the actual carriage-driving mechanism
110
, it is very difficult to completely remove the eccentricity of the pulleys
111
and motor
113
.
Additionally, an action of the image-recording apparatus including the carriage-driving mechanism
110
in the ideal state will be described hereinafter with reference to FIG.
13
.
FIG. 13
is a diagram showing shot positions that the ink drops ejected in the above-described ideal state take on the recording-medium
200
. Additionally,
FIG. 13
is a schematic enlarged top plan view showing the operating recording-heads of the image-recording apparatus of FIG.
12
. Additionally, in the following description, a case in which the image-recording apparatus records the image in the reciprocating print mode, particularly one path reciprocating print mode.
In
FIG. 13
, a reference character Vf denotes a set movement speed in the forward movement of the recording-head
130
, and reference character Vr denotes the set movement speed in the backward movement of the recording-head
130
. Additionally, the set movement speeds Vf, Vr in the forward and backward movements are set to be the same in order to move the carriage
120
at the constant speed. Furthermore, in the image-recording apparatus, the carriage-driving mechanism
110
in the ideal state drives the recording-head
130
via the carriage
120
. As a result, the speed of the recording-head
130
in the reciprocating movement is constantly the same as the set movement speeds Vf, Vr.
First, the action of the recording-head
130
which moves in the forward movement will be described.
The recording-head
130
in
FIG. 13
is moved by the carriage-driving mechanism
110
along the main scanning direction in the ideal state. Therefore, the recording-head
130
moves at the set movement speed Vf as set along the main scanning direction.
The recording-head
130
is apart from the recording-medium
200
by a distance Dg. Therefore, a time t obtained by the following equation 1 is required from when the ink drops are ejected from the recording-head
130
until the ink drops are shot on the recording-medium
200
.
t=Dg/Vi
  Equation 1
Where Vi is a eject speed of ink
Subsequently, in the forward movement, the ink drops are ejected from the recording-head
130
which is moving at the speed Vf, and therefore deviate from ejecting positions toward a forward direction of the recording-head
130
. Therefore, in the forward movement the ink drops ejected from the recording-head
130
have shot positions which deviate from the eject positions by a dist

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