Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2001-11-13
2003-10-14
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S067000
Reexamination Certificate
active
06631966
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording apparatus of serial type, and more particularly to a recording head having a heat generating portion for generating thermal energy to be used for recording and an apparatus provided with such recording head.
2. Related Background Art
The recording apparatus of ink jet system executes recording by discharging a droplet of recording liquid (ink) from a discharge port of a recording head and depositing such droplet onto a recording medium. In the recording apparatus employing such ink jet system, for example a serial ink jet printer, the recording is executed by discharging ink from the recording head while it is moved in a main scanning direction and conveying the recording medium by a recording medium conveying member (roller) between the scanning motions.
Among the recording heads, there is known a recording head for discharging a micro droplet of liquid utilizing thermal energy generated for example by an electrothermal converting member and a recording head for discharging a liquid droplet by deflection with a pair of electrodes. Among these heads, the recording head discharging liquid droplet by utilizing thermal energy is provided with advantages such as that recording of a high resolution is possible because the ink discharging portions (discharge ports) can be arranged with a high density and that the entire recording apparatus can be easily compactized, and is therefore commercially utilized.
FIG. 15
is a perspective view showing an example of a serial ink jet recording apparatus, in which the recording head thereof is provided with a head casing, having detachable ink tanks
50
. The head casing
51
is provided, on a rear face thereof (opposite to a face on which the ink tank
50
is mounted), with an ink supply portion
55
having ink flow paths communicating with ink supply apertures of the ink tanks
50
respectively through liquid chambers, and discharge portions
52
are provided on the ink supply portion
55
across a support member (heat dissipating member)
54
.
The ink supply portion
55
and the support member
54
are mutually fixed by adhesion, and the support member
54
and the discharge portions
52
are mutually fixed by adhesion. The support member
54
is provided with plural ink flow paths for supplying the discharge portions
52
respectively with inks, and these ink flow paths are respectively connected with those of the ink supply portion
55
. Since the precision of the discharge portions
52
is extremely important, the support member
54
has to be composed of a material of high heat resistance and high flatness and is generally composed of a metal or a ceramic material.
Each discharge portion
52
is provided with plural discharge ports arranged with a predetermined pitch in a longitudinal direction (crossing the scanning direction (for example, perpendicularly)), and an energy conversion element such as an electrothermal converting element is provided for each discharge port. The discharge portion
52
is electrically connected with a flexible cable
53
through which electrical signals for driving the energy conversion elements are supplied from an unrepresented control unit. In order to reduce the electrical resistance, the flexible cable
53
usually has an area approximately equal to a discharge surface of the support member
54
(a surface of support member
54
facing discharge portions
52
) and is so provided as to cover the discharge surface of the support member
54
.
The recording head shown in
FIG. 15
is provided with a discharge portion
52
for each ink tank
50
, and the number of such ink tanks and discharge portions is variable depending on the specifications.
In the following there will be given a more detailed description of the structure of the discharge portion of the conventional recording head.
FIGS. 16A and 16B
are respectively a perspective view and an exploded perspective view of the discharge portion of a conventional recording head, wherein the discharge portion
52
, the support member
54
and the ink supply member
55
are basically similar to those shown in
FIG. 15
except for a difference in the shape and in the number of ink flow paths.
The support member
54
is provided with plural ink flow paths
54
a
, and the discharge portions
52
are fixed by adhesion on each of the ink flow paths
54
a
, respectively. The ink supply portion
55
is composed of a molded member (for example, of organic resinous material) and is provided with plural ink flow paths
55
a
respectively corresponding to the ink flow paths
54
a
of the support member
54
, and the support member
54
is fixed by adhesion in such a manner that the corresponding ink flow paths are mutually connected. The adhesion between the discharge portions
52
and the support member
54
, and between the support member
54
and the ink supply portion
55
, is achieved by an adhesive material of a very high thermal conductivity.
Each discharge portion
52
is provided with plural discharge ports in the longitudinal direction thereof (crossing the scanning direction (for example, perpendicularly)), and an electrothermal converting element is provided for each discharge port. At ink discharge, an electrical pulse is applied according to drive data to the electrothermal converting element of each discharge port, whereby film boiling is generated in the ink and the ink is discharged from the discharge port by the growth of a bubble generated by the film boiling.
The heat generated in such ink discharge is considered to be dissipated principally by the following three processes:
(1) heat dissipation to the discharged ink itself;
(2) solid heat conduction from the discharge portions
52
to the support member
54
and the ink supply portion
55
; and
(3) heat dissipation from the discharge portions
52
, the support member
54
and the ink supply portion
55
to the external space (air).
In the conventional recording head, as explained in the foregoing, the heat generated in the discharge portions
52
at ink discharge is partly taken away by the discharged ink droplet itself and is dissipated by solid heat conduction and heat dissipation. In the aforementioned conventional recording head, the heat movement is generally much faster and larger in the solid heat conduction to the support member
54
than in the heat dissipation to the air. Consequently the heat generated in the discharge portions
52
is immediately transmitted to the support member
54
. However, since the material employed in the ink supply portion
54
generally has a low heat conductivity, the solid heat conduction from the support member
54
to the ink supply portion
55
is not performed effectively, so that the heat transmitted to the support member
54
is eventually dissipated from the surface thereof into the air. In this manner, the cooling or heat dissipation in the conventional recording head principally relies on the heat dissipation from the surfaces of the discharge portions
52
and the support member
54
except for the part of the heat dissipated by the discharged ink droplet itself. For this reason, heat tends to accumulate in the head and, since the heat capacity is not so large, there easily results an increase in the temperature. Especially in a configuration in which the surface of the support member
54
is covered by the flexible cable
53
, heat tends to accumulate more in the head, thus leading to a further temperature increase, because an additional process of heat conduction from the support member
54
to the flexible cable
53
is required.
An excessive increase in the temperature of the head may result in the following drawbacks:
(1) ink cannot be discharged (non-discharge);
(2) bursting of ink droplet at discharge;
(3) accelerated kogation and deterioration of the electrothermal converting element (heat generating member or heater); and
(4) fluctuation of recording density in recording on a recording medium such as paper.
It is therefore an important issu
Kurata Mitsuru
Ono Takayuki
Shirakawa Hiroaki
Tajima Hiroki
Watanabe Itaru
Gordon Raquel Yvette
Stephens Juanita
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