Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1998-02-19
2002-03-26
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S006000, C347S019000
Reexamination Certificate
active
06361136
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid-jet printing apparatus and a liquid container for performing printing on a print medium by discharging liquid and, more particularly, to a detection system which can detect whether or not an ink level in a liquid container reaches a predetermined level, liquid-jet printing apparatus using the detection system, liquid container used together with the system and apparatus, and a system of receiving changes in amount of light.
According to the conventionally known devices for detecting existence
on-existence of ink in an ink tank containing ink, electrodes are provided in the ink tank and electric conductivity between the electrodes is measured, or a discharged ink droplet is optically detected. Generally, a method of using electrodes complicates the structure of the ink tank. Thus, means for optically detecting existence
on-existence of ink is usually employed.
Particularly, a liquid-jet printing apparatus for performing printing by discharging liquid, generally comprises print means (printhead), an ink tank (liquid container), conveyance means for conveying a print medium and control means for controlling the above means. Herein, if ink left in the ink tank is lower than a predetermined amount, ink supplied to the printhead becomes insufficient and may cause discharge failure. For this reason, an apparatus for detecting a residual ink amount or existence
on-existence of ink in an ink tank has been suggested.
As ink-existence detection apparatus of this type, for instance, Japanese Patent Application Laid-Open (KOKAI) No. 8-112907 discloses an ink-jet printing apparatus which detects existence
on-existence of ink in an ink tank having a negative-pressure-generating member e.g. absorbent material, foaming material and the like, by transmitting light through a part of the transparent or semi-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 member.
Furthermore, U.S. Pat. No. 5,616,929 discloses an ink tank integrating an optical ink detection portion, formed with a light-transmitting material made of the same material as the ink tank, where the surface contacting ink has a predetermined angle with respect to a detection light path.
Moreover, in a case where an ink tank is detachable from a printing apparatus, the printing apparatus needs to automatically determine whether or not the ink tank is properly attached to the printing apparatus at the time of printing operation. For this, Japanese Patent Application Laid-Open (KOKAI) No. 9-174877 discloses a sensor system for detecting existence of an ink tank and ink of a predetermined level in the ink tank.
As described above, in the sensor system for detecting existence of an ink tank and ink level in the ink tank (or existence
on-existence of ink in the ink tank), it is desirable to share a detection sensor (light emission device and photoreceptor) so as to simplify the structure of the printing apparatus including the sensor system. Japanese Patent Application Laid-Open (KOKAI) No. 9-29989 discloses an ink-jet printing apparatus capable of detecting existence
on-existence of ink and existence
on-existence of an ink tank by a single photosensor.
Besides the above, Japanese Patent Application Laid-Open (KOKAI) No. 7-89090 is known as a detection apparatus for detecting liquid existence in a liquid container comprising: a negative-pressure generating member accommodating chamber accommodating a negative-pressure-generating member and having a liquid supply opening and atmospheric-air communicating portion; and a liquid containing chamber, which forms a substantially enclosed space, having a communicating portion connecting to the negative-pressure generating member accommodating chamber.
The use of the above-described sensor system is a reasonable approach in detecting existence
on-existence of an ink tank and ink of a predetermined level (or existence
on-existence of ink) in the ink tank with low cost.
However, since the above sensor system utilizes an optical sensor, it is preferable to satisfy the following requirements with low cost for more accurate detection, taking into consideration an expected life span of an optical device influenced by deterioration of a light emission device, a stained photoreceptor or the like, non-precise formation of the surface of a reflector, changes in an amount of light and so on in the surrounding environment.
The first requirement is to improve precision in detection by increasing an S/N (signal
oise) ratio. The second requirement is to accurately discriminate between the detection of existence
on-existence of an ink tank and the detection of ink of a predetermined level (or existence
on-existence of ink) in the ink tank when these are detected by a single sensor.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation, and has as its first object to provide a practical detection system which can improve precision in detection by reducing noise received by a photoreceptor, liquid-jet printing apparatus using the detection system, and liquid container used together with the system and apparatus.
A second object of the present invention is to provide a liquid container which can accurately discriminate between the detection of existence
on-existence of a liquid container and the detection of a liquid level (or existence
on-existence of liquid) in the container when these are detected by a single sensor.
A third object of the present invention is to provide a detection system and liquid container which can improve precision in detection by reducing noise received by the photoreceptor, and which can accurately discriminate between the detection of existence
on-existence of a liquid container and the detection of a liquid level (or existence
on-existence of liquid) in the container when these are detected by a single sensor.
A fourth object of the present invention is to provide a liquid-jet printing apparatus which can accurately discriminate between the detection of existence
on-existence of a liquid container and the detection of a liquid level (or existence
on-existence of liquid) in the container when these are detected by a single sensor, even if the first requirement is not satisfied.
In order to attain the above first object, the detection system according to the present invention has the following configuration.
More specifically, the present invention provides a detection system comprising: optical means including a light emission unit for emitting light to a liquid container and a light receptor for receiving reflected light of the emitted light; a prism formed with light transmitting material, the prism having a surface constructing a part of an external wall surface of the liquid container and plural reflection surfaces, which are different from the surface, each being in contact with liquid and having a predetermined angle with respect to a light path of the emitted light; and determination means for determining whether or not the liquid in the liquid container exists based on the reflected light of the light emitted on the prism and received by the optical means, wherein the liquid container has a diffusion portion, provided in between a portion opposing to the light emission unit and another portion opposing to the light receptor of the prism, for diffusing light reflected on the external wall surface of the liquid container so as to prevent the reflected light from returning to the light receptor of the optical means.
Note that light in this present invention includes not only visible light but also infrared rays or the like.
Further note that it is preferable that the prism is provided on the bottom surface portion of the liquid container.
Furthermore, it is preferable that the diffusion portion is a concave polyhedral portion provided in the center of the bottom surface portion of the prism, or that the diffusion port
Hiramatsu Soichi
Sato Osamu
Takagi Shinji
Udagawa Kenta
Watanabe Itaru
Barlow John
Canon Kabushiki Kaisha
Dudding Alfred
Fitzpatrick ,Cella, Harper & Scinto
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