Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2002-03-29
2003-09-09
Gordon, Raquel Yvette (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06616255
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to an ink cartridge to be used in printing apparatuses, such as printers, copy machines, and facsimile machines. More particularly, the invention pertains to an ink cartridge wherein detection accuracy of an ink remaining amount in the ink cartridge using an optical device can be improved.
2. Description of Related Art
There has been provided ink cartridges, used in printers or the like, that are structured so that ink level in the ink cartridges can be detected using an optical device. In the ink cartridge of this type, generally, ink is stored in a light-permeable case. The ink level is detected through the use of change in an amount of reflected light caused in accordance with the ink level, by which light is irradiated into the ink cartridge from a light source.
FIGS. 16A and 16B
show a principle of detection of the presence or absence of ink in a conventional ink cartridge
200
. As shown in
FIGS. 16A and 16B
, the ink cartridge
200
is molded using a light-permeable material (e.g. resin materials, such as polypropylene), and includes a main ink tank
203
that accommodates therein a foam (porous material)
202
capable of impregnating ink
201
and a sub-ink tank
205
to which light is applied from an ink sensor
204
. The ink
201
is stored in both main and sub-ink tanks
203
,
205
. An ink jet head
207
is connected to the bottom of the ink cartridge
200
via an ink supply hole
206
. The ink
201
is supplied from the ink cartridge
200
through the ink supply hole
206
and is ejected from the ink jet head
207
. As a result, an image can be obtained on a recording medium.
In the ink cartridge
200
, first, the ink
201
in the main ink tank
203
is gradually consumed (see FIG.
16
A). After the ink
201
in the main ink tank
203
nearly runs out, the ink
201
in the sub-ink tank
205
is used (see FIG.
16
B). The ink sensor
204
includes a light-emitting device
204
a
that irradiates infrared light toward the ink cartridge
200
and a photoreceptor device
204
b
that receives light reflected from the ink cartridge
200
. The ink sensor
204
is disposed so as to be able to irradiate the infrared light toward the sub-ink tank
205
.
As shown in
FIG. 16A
, when the ink cartridge
200
contains a large amount of ink (when the ink cartridge
200
contains the ink
201
in both the main and sub-ink tanks
203
,
205
), infrared light irradiated from the light-emitting device
204
a
of the ink sensor
204
(an optical path a
1
) travels in the ink cartridge
200
in a direction indicated with an optical path a
2
while permeating the ink
201
, because a refractive index of the material forming the ink cartridge
200
is close to a refractive index of the ink
201
. Therefore, the infrared light is absorbed by the ink
201
, so that an extremely small amount of the light is to be reflected from the inside of the ink cartridge
200
toward the photoreceptor device
204
b
in the ink sensor
204
. Even when the photoreceptor device
204
b
receives such the amount of the reflected light, it is not determined that the ink is absent.
As opposed to this, as shown in
FIG. 16B
when the ink
201
is absent at the upper area of the sub-ink tank
205
of the ink cartridge
200
, the infrared light irradiated from the light-emitting device
204
a
in the ink sensor
204
(an optical path b
1
) is reflected at a phase boundary between air
208
and inner surface of an outer wall of the sub-ink tank
205
(an optical path b
2
), because the refractive index of the material forming the ink cartridge
200
is different from a refractive index of the air
208
. Accordingly, a large amount of the light is reflected from the inside of the ink cartridge
200
toward the photoreceptor device
204
b
in the ink sensor
204
. Accordingly, the photoreceptor device
204
b
receives the large amount of the reflected light, so that it is determined that the ink is absent.
As described above, the amount of the light to be reflected from the ink cartridge
200
changes in accordance with the presence or absence of the ink
201
at a predetermined level in the sub-ink tank
205
. Therefore, a remaining amount of the ink
201
in the ink cartridge
200
can be detected by which a difference of the reflected light amount between the presence of the ink
201
and the absence of the ink
201
is detected using the photoreceptor device
204
b
in the ink sensor
204
.
When the ink cartridge
200
contains a certain level of the ink
201
(when the level of ink
201
in the sub-ink tank
205
is up to the upper area of the sub-ink tank
205
although the ink
201
in the main ink tank
203
almost runs out (not shown)), the ink
201
is not absorbed in the foam
202
. Therefore, infrared light irradiated from the light-emitting device
204
a
in the ink sensor
204
(an optical path a
1
) is reflected by the inner wall of the main ink tank
203
or the foam
202
(an optical path a
3
).
In this case, when the ink cartridge
200
contains intensely colored ink, such as black and cyan ink, a certain amount of the infrared light irradiated from the light-emitting device
204
a
in the ink sensor
204
(the optical path a
1
) is absorbed by the foam
202
. Thus, an amount of reflected light that cannot be determined as the absence of ink, is reflected from the ink cartridge
200
toward the photoreceptor device
204
b
in the ink sensor
204
.
However, when the ink cartridge
200
contains light-colored ink, such as yellow and magenta ink, a problem occurs that an amount of ink remaining in the ink cartridge
200
cannot be correctly detected. That is, the infrared light is hardly absorbed by light-colored ink, so that the infrared light that travels in the ink cartridge
200
containing the light-colored ink is reflected by the foam
202
. Thus, the photoreceptor device
204
b
would receive a large amount of the reflected light (the optical path a
3
in
FIG. 16A
) though the ink cartridge
200
contains the ink
201
in both main and sub-ink tanks
203
,
205
. Therefore, the difference of the reflected light amount between the presence and the absence of the ink
201
at the predetermined level in the sub-ink tank
205
is small, so that the amount of the ink
201
remaining in the ink cartridge
200
cannot be precisely detected.
SUMMARY OF THE INVENTION
The invention provides an ink cartridge wherein detection accuracy of a remaining amount of ink in the ink cartridge using an optical device can be improved.
According to one aspect of the invention, an ink cartridge includes an ink tank that can store ink therein, and is detachable from an image forming apparatus that forms an image using the ink. An ink detection window, permeable to light, is disposed to an outer wall surface of the ink tank. An optical path direction changing member is disposed inside the ink tank, at a predetermined distance away from a surface of the ink detection window that contacts the ink. The optical path direction changing member changes a direction of an optical path of the light that passes through the ink detection window. On the ink cartridge, the ink detection window is inclined at a predetermined angle with respect to the optical path direction changing member.
According to the ink cartridge, when the ink cartridge is attached to the image forming apparatus, the ink stored in the ink tank is supplied to the image forming apparatus. The ink detection window, that is permeable to light, is disposed to the outer wall surface of the ink tank. When the level of ink the ink tank is not up to the ink detection window, light irradiated toward the ink detection window by a light-emitting device provided in the image forming apparatus is reflected at an inner surface of the ink detection window and the reflected light travels toward a photoreceptor provided in the image forming apparatus.
When the level of ink in the ink tank is up to the ink detection window, the light permeates a phase boundary between the ink and the ink detection window
Murakami Atsushi
Yoshiyama Masatoshi
LandOfFree
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