Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1999-05-20
2002-03-05
Hallacher, Craig A. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S037000, C347S050000
Reexamination Certificate
active
06352325
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a device for determining a quantity of consumable product contained in at least one reservoir, of the type comprising a capacitive arrangement having a conductive plate associated with such a reservoir, for instance having such a plate normally pressed against a wall of such a reservoir, in order to produce a signal representing the quantity of product contained in the said reservoir.
The invention also concerns an improvement facilitating the fitting of the reservoir in spite of the presence of such a conductive plate, whilst increasing the useful surface of the latter (and consequently the capacitance of the capacitor thus formed), all other things being equal.
The invention also concerns a document printing device having a chassis and a carriage compelled to move along guidance means on this chassis and in which the said carriage carries at least one removable printing product reservoir and a conductive plate able to constitute a capacitor in association with the reservoir in question, the printing device having means of determining the quantity of printing product contained in the reservoir, provided with the improvement mentioned above.
A conventional printing device has one or more reservoirs and a corresponding number of print heads, mounted on a carriage compelled to move along guidance means arranged on a chassis. The printer is completed by a mechanism for moving a printing medium (the sheet of paper), also arranged on the chassis. The said printing medium is moved perpendicularly to the path of the carriage. The latter has a support on which the reservoir or reservoirs are mounted, these being removable individually or in a group or groups. Thus, on an improved printer, there may be up to five reservoirs. Three reservoirs are filled with printing products for the three primary colours: cyan, magenta and yellow, a fourth reservoir is filled with black printing product and a fifth can be provided for containing a colourless product sprayed onto the paper in order to optimise the conditions of application of the pigmented products.
Several reservoirs can be grouped together in a cartridge, for example grouping together the three primary colours, or on the other hand be independent of each other in order to be able to be changed individually. Each reservoir or group of reservoirs is therefore removably mounted on the carriage support. The corresponding print head or heads can be integral with the reservoir or reservoirs (in which case they are changed at the same time as the reservoir or cartridge). In other cases, the print head or heads are mounted permanently on the carriage.
Several ways are known for detecting a printing product level in a reservoir of such a printing device. Notably, it is known that there can be associated with the reservoir a capacitive arrangement placed in a resonant circuit to which an excitation signal is applied, generally a high-frequency alternating signal. The signal transmitted by such a capacitive arrangement varies according to the quantity of ink remaining in the reservoir. This variation can therefore be used for indicating to the user the degree to which the reservoir is filled or at least the fact that a minimum level has been reached. According to the information collected, the user can replace the reservoir or change a cartridge containing this reservoir. Where the carriage carries several reservoirs, the capacitive arrangement designated above comprises several capacitors each surrounding one of the reservoirs.
The document EP 0 028 399 describes a system of this type in which the capacitor is formed by two metal plates between which the ink reservoir is situated. A resonant oscillating circuit is calibrated so that its resonant frequency is reached when the ink level has dropped to a predetermined value.
Several solutions have also been experimented with in order to connect the elements of the device which are on the carriage to those which are on the fixed chassis. For example, a resonant circuit can be mounted on the carriage, the capacitor of this circuit including the reservoir. One resonant circuit per reservoir can be established and an analogue switch can be used for successively making the measurements corresponding to the different reservoirs. Such a system is relatively expensive if it is necessary to provide one resonant circuit per reservoir. The use of an analogue switch also creates stray capacitances which substantially interfere with the measurements.
If the resonant circuit is placed on the chassis, the signals must then be conveyed by flexible cables connecting the carriage and the chassis. These cables create problems of electromagnetic compatibility due to the conveyance of high-frequency signals, and stray capacitances and inductances are also created between the cables, which also interfere with the measurements.
Moreover, if the measurement circuits are placed on the carriage, the latter can be the origin of electrostatic discharges.
Furthermore, in such a system, it is clear that the reservoir or reservoirs must be mounted removably on the carriage and that at least one conductive plate, forming part of the aforementioned capacitive arrangement, must also be carried by the carriage. Since it is a case of measuring a level of liquid product contained in the reservoir, the said plate must be pressed against a normally vertical face of the reservoir. Thus, considering
FIGS. 1 and 2
, which illustrate the state of the art,
FIG. 1
depicts a reservoir A on the point of being mounted on a support B on the carriage.
FIG. 2
shows the reservoir installed on this support. A comparison of the two figures shows that it is necessary to incline the reservoir in order to fit it (FIG.
1
), which makes it necessary to provide an end wall with an inclined part D. In the end, only the lower part of the corresponding face of the reservoir is in contact with the lower part of the said end wall C. However, it is advantageous, for various technical reasons which will emerge later, to arrange the said conductive plate against the end face E of the reservoir. It will be understood under these circumstances that the surface of the conductive plate would be limited in order to concern, from the electrical point of view, only the lower part of the reservoir in order not to interfere with the fitting of the latter. The capacitance of the capacitor which would be available for making the measurement would be relatively limited.
SUMMARY OF THE INVENTION
The invention makes it possible to overcome all these drawbacks.
One important idea of the invention consists of arranging electrical connection means between the chassis and the carriage in order to electrically bring into service a capacitor plate associated with a reservoir when the said carriage occupies a predetermined position. If the carriage carries several reservoirs, several corresponding predetermined positions are thus defined, for which the level measurements can be made individually and successively for the different reservoirs.
More precisely, the invention concerns a device for determining a quantity of consumable product contained in at least one reservoir, of the type comprising the following components: a capacitive arrangement including a conductive plate associated with the said reservoir, excitation signal production means able to be connected to the said capacitive arrangement, and detection and measurement means for detecting and processing a resulting signal transmitted by the said capacitive arrangement and representing a quantity of product contained in the said reservoir, characterised in that, some of the components mentioned above being mounted on a chassis and others being fixed to a movable carriage moving along a guidance means on the said chassis, electrical connection means are arranged between the said chassis and the said carriage in order to electrically bring into service the said plate corresponding to the said reservoir, for a predetermined position of the said carriage.
Preferably, the
Coudray Pascal
Froger Marie-Helene
Lorgeoux Mickaël
Truffaut Christophe
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hallacher Craig A.
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