Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1997-11-13
2001-10-02
Nguyen, Judy (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06296354
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a liquid container for containing liquid, more particularly to an ink container for containing ink usable for recording and an ink jet recording apparatus.
In a recording apparatus such as a printer, copying machine or facsimile machine or a recording apparatus used as an output apparatus for a combined electronics apparatus or work station including a computer, word processor or the like, an image is recorded on a recording material such as a sheet of paper or a plastic thin film in accordance with image information. The recording apparatus is classified into a ink jet type, a wire dot type, a thermal type and a laser beam type depending on the recording system.
A recording apparatus of an ink jet type is such that a droplet of ink are ejected from a recording head onto a recording material. This type has the following advantages:
1. The size of the recording means can be easily reduced, and a high resolution image can be recorded at a high speed.
2. The recording is possible on plain paper, and the running cost is low because the ink is consumed in accordance with the information to be recorded.
3. The recording is a non-impact type without contact to the recording material, and therefore, the noise is low.
4. Color image formation is easy by using multi-color inks.
As the means for ejecting the ink, thermal energy generating means such as sheet generating element is known. The type in which the ink is ejected using thermal energy is called “bubble jet”, and is advantageous over the piezoelectric type in the high density and high speed recording.
The recording head for the ink jet type using the thermal energy can be formed through semiconductor manufacturing process including etching, evaporation, sputtering or the like to construct electrothermal transducers, electrodes, passage walls and top plate. Therefore, liquid passages (ejection outlets) at a high density, can be easily manufactured, so that further downsizing is possible.
In an ink jet recording system, an ink container for containing ink to be supplied to the recording head is fixed at a predetermined position in an ink jet recording apparatus in one system, and the ink container is mounted on a carriage together with a recording head in another type. In the former type, an ink supply passage in the form of an ink tube or the like is provided between the recording head and the ink container to follow movement of the carriage. In the latter type, the ink supply passage between the recording head and the container is relatively short. Therefore, the type having the ink container on the carriage is suitable for the downsizing and the simplification of the ink jet recording apparatus,
Among the structures in which the recording head and the ink container are both carried on a carriage, the recording head and the ink container are integrally formed in one type, and the recording head and the ink container are separable in another type.
In the type in which the recording head and the ink container are integral with each other, the cartridge constituted by the ink container and the recording head is replaced with a new cartridge when the ink in the ink container is used up, and therefore. the handling is easy. For this reason, this type is widely used recently. However, the relatively expensive recording head has to be exchanged whenever the ink in the ink container is used up, the running cost increases.
In the type in which the recording head and the ink container are separable, only the ink container containing the ink is exchanged when the ink is used up, and therefore, the recording head may be exchanged only when the service life of the recording head ends.
In the normal use, the service life of the recording head is not shorter than the period in which the ink in ink container is used up. For this reason, the number of exchanges of the expensive recording heads is smaller than that of the ink container, thus reducing the running cost. However, in the case of the separable recording head and the ink container, the connecting portion between the ink container and the recording head is required to have such a structure as to prevent ink leakage.
In a recording apparatus using an ink jet type, it is desired that the ink is properly supplied in accordance with ejections of the ink through the recording head by the recording operation and that the ink does not leak out through the ejection outlets during the recording operation.
The ink leakage through the ejection outlet is a problem peculiar to the ink jet recording. In order to solve this problem, the pressure at the ejection outlets is maintained at a lower level than the ambient pressure. In order to provide such a pressure, the ink supply system is provided With a vacuum producing mechanism. Here, the vacuum means a back pressure against the ink supply to the ejection outlet and particularly means the pressure lower than the ambient pressure.
When the ink container is a replaceable type, it is further desired in addition to the above that the ink container can be easily mounted or demounted without ink leakage and that the ink can be supplied to the recording head with certainty.
In any of the above-described various ink jet recording apparatuses, it is desired that the ink containing means is replaced at proper timing, and therefore, it is desired that the quantity of the ink remaining in the ink container is correctly detected and/or that the ink empty timing is properly detected.
When the ink in the ink container is used up during a recording operation, ink ejecting means is operated to produce ejection energy with non-existence of the ink. In an ink jet recording apparatus in which the ink is ejected using pressure produced by state change of the ink caused by the heat, the temperature of the recording head is unnecessarily increased if the thermal energy generating means is actuated without the ink, and therefore, the recording head itself may be damaged.
In an ink jet recording apparatus in which mechanical pressure generating means such as piezoelectric element or the like as the ejection means, the pressure continues to be produced without load for ink ejection, so that the ejection means is deteriorated, thus reducing the durability.
As for the means for detecting ink container empty, Japanese Laid-Open Patent Application No. 133733/1979 discloses detecting the transparency of the ink container using an optical element, and Japanese Patent Application Publication No. 17465/1989 discloses electrodes, and Japanese Laid-Open Patent Application No. 194853/1984 discloses counting the number of ejection pulses to predict the used amount of the ink (dot count type).
In an ink jet recording apparatus it is preferable in order to stably eject the ink through the recording head and to prevent leakage of the ink through the ejection outlet during the stand-by period that the ink at the ejection outlet is maintained always at proper vacuum condition. In the conventional ink jet recording apparatus, as a means for realizing the vacuum state, a level of the ink in the container is maintained at a level lower than that of the recording head at all times. In such an ink jet recording apparatus, the gravity is used, and therefore, the position or pose of the apparatus has to be fixed during use.
In such an ink jet recording apparatus, the detection of the remaining amount of the ink is relatively easy. It may be detected by using float to detect the level of the ink in the container, or a plurality of electrodes may be disposed so as to be exposed above the liquid level at a certain liquid level, and the impedance change between the electrode is detected.
However, small size or portable ink jet recording apparatus is desired recently, in which the ink container is desired to be mounted on the recording apparatus, as contrasted to the prior apparatus wherein the ink container is mounted in the apparatus away from the carriage. As an ink container in which proper negative pressure is produced for the r
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Nguyen Judy
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