Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1999-10-25
2003-04-01
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06540314
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink tank, a cartridge including the ink tank, and a printing apparatus using the cartridge, and more particularly, an ink tank supplying ink to a printhead which performs printing according to an ink-jet printing method, a cartridge including the ink tank, and a printing apparatus employing the cartridge.
Conventionally, as a method of detecting the amount of ink residue in an ink tank containing ink or detecting existence/absence of ink in the ink tank, optical detection of the amount of ink residue or ink existence/absence is known.
For instance, Japanese Patent Application Laid-Open (KOKAI) No. 8-112907 discloses an ink-jet printing apparatus which detects the amount of ink residue in an ink tank having a negative pressure generating material e.g. absorbent material, foaming material or the like, by transmitting light through a part of the transparent wall surface of the ink tank and detecting changes in optical reflectance in the boundary portion between the wall surface of the ink tank and the negative pressure generating material.
Furthermore, Japanese Patent Application Laid-Open (KOKAI) No. 7-218321 discloses an ink tank comprising an optical ink detection unit which is formed with a light-transmitting material made of the same material as the ink tank, and the boundary surface between ink and the optical ink detection unit has a predetermined angle with respect to an optical path. Still further, Japanese Patent Application Laid-Open (KOKAI) No. 9-29989 discloses an ink-jet printing apparatus capable of detecting existence/absence of ink and existence/absence of an ink tank by a single photosensor serving as both light-emission device and photoreceptor.
Besides the aforementioned apparatuses, Japanese Patent Application Laid-Open (KOKAI) No. 7-89090 discloses an apparatus for detecting existence or absence of liquid in a liquid container comprising: a negative-pressure-generating-material housing chamber which houses a negative pressure generating material and has a liquid supply opening and an air hole; and a liquid containing chamber which has a channel connected with the negative-pressure-generating-material housing chamber and forms a substantially enclosed space.
Herein, the conventional ink existence/absence detection mechanism utilizing a light-transmitting prism is explained with reference to FIG.
6
.
FIG. 6
shows a positional relation among a light-transmitting prism provided on the bottom surface of an ink tank, a light emission device which emits light on the prism, and a photoreceptor which receives the emitted light.
As shown in
FIG. 6
, a prism
1060
is integrally molded to the bottom portion
1061
of the ink tank. Light emitted externally by a light emission device
1062
from the bottom of the ink tank is incident on the prism
1060
.
When the ink tank is sufficiently filled with ink, the incident light takes the optical path I→II′ as shown in FIG.
6
and is absorbed by the ink, so that the light does not return to the photoreceptor
1063
. On the other hand, when the ink is consumed and the ink tank contains no ink, the incident light is reflected by the oblique portion of the prism
1060
and takes the optical path I→II→III, then reaches the photoreceptor
1063
as shown in FIG.
6
. In the foregoing manner, ink existence/absence is detected by whether or not the light emitted by the light emission device
1062
returns to the photoreceptor
1063
.
Note that the light emission device
1062
and photoreceptor
1063
are provided in the main body of a printing apparatus.
The above-described ink existence/absence detection mechanism may be regarded as a rational method of realizing detection of an ink level or ink existence/absence in an ink tank at low cost.
Meanwhile, another configuration is also known for performing such optical ink residue detection. More specifically, water repellent processing is performed on a component provided in the optical path so as to avoid an ink droplet from being attached to the component. By this configuration, even when the amount of ink in the ink tank decreases, it is possible to avoid erroneous ink residue detection caused by the ink droplet attached to the surface of the component provided in the optical path.
For instance, Japanese Patent Application Laid-Open (KOKAI) No. 7-237300 discloses a construction utilizing silicone or Teflon resin as a water repellent agent in order to avoid ink droplet attachment to the side wall surface of the ink tank or light reflector, serving as a component provided in the optical path. In addition, Japanese Patent Application Laid-Open (KOKAI) No. 8-187873 discloses a technique of performing surface processing such as water repellent or oil repellent processing on the inner wall surface of an ink tank, which serves as a component provided in the optical path, instead of polishing the inner wall surface of the ink tank to reduce the surface roughness thereby enlarging the contact angle between ink and the ink tank inner wall surface.
However, recently, higher image quality and higher printing quality are required in ink-jet printing apparatuses, and the types of ink used in printing apparatuses are diversified. Inks used are, for instance, an aqueous pigment ink in which pigment serving as a colorant is dispersed in water with the use of a dispersant, or an aqueous pigment ink utilizing self-dispersing pigment capable of stable dispersion without using a dispersant by reforming the surface of the pigment, or a dispersing-type ink such as micro-emulsion ink or the like in which an oil-base dye is dispersed by emulsification.
Inventors of the present invention have used such ink, in which a colorant is dispersed, in the above- described conventional examples, and discovered that in the environment of a high temperature, even if there is no ink droplet attached to the inner portion of an ink tank, light emitted by a light emission device for ink residue detection and incident upon the ink tank does not always return to a photoreceptor.
As a result of careful study of the above problem by the inventors, the inventors have discovered that, particularly in the environment of a high temperature, dispersion of the colorant becomes unstable and the colorant adsorbs to the inner wall of the ink tank. When the colorant adsorbs to the inner wall of the ink tank, the light emitted by the light emission device for ink residue detection and incident upon the ink tank is absorbed by the colorant adsorbed to the inner wall of the ink tank.
Because of this, despite the fact that ink does not exist in the ink tank, determination is made that ink still exists in the ink tank.
SUMMARY OF THE INVENTION
The present invention is made in consideration of the result of the above study, and has an object to provide an ink tank which enables accurate detection of existence/absence of liquid even when using the type of ink in which a colorant is dispersed, a cartridge including the ink tank, and a printing apparatus employing the cartridge.
According to one aspect of the present invention, the foregoing object is attained by providing an ink tank, in which a part of a storage containing ink where a colorant is dispersed, is coated with a low surface energy processing agent including alkyl polysiloxane.
Herein, it is preferable that acid be included in the low surface energy processing agent.
Furthermore, it is preferable that the alkyl polysiloxane coated on the part of the storage be 1 to 15 &mgr;g per unit area (1 mm
2
).
Furthermore, the storage comprises a prism having a first surface which receives light emitted by an external device, and a second surface which receives the light reflected by the first surface and changes an optical path of the light received such that the optical path of the light is headed to the external device, the prism formed with a light-transmitting material, provided on a bottom portion of the storage, and protruded from the bottom portion of the storage toward an interior of the storage,
Hattori Yoshifumi
Kitabatake Kenji
Koshikawa Hiroshi
Mishina Shinya
Morita Osamu
Canon Kabushiki Kaisha
Feggins K.
Fitzpatrick ,Cella, Harper & Scinto
Le N.
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