Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2000-04-11
2001-11-06
Nguyen, Thinh (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S086000
Reexamination Certificate
active
06312084
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an ink jet recording apparatus provided with an ink jet head for effecting recording with flying ink droplets utilizing the film boiling phenomenon of liquid ink.
2. Related Background Art
In recent years, various ink jet recording methods have been put into practical use because in such recording methods, the creation of noise during recording is negligibly small and in addition, recording can be effected on plain paper.
Among such methods, the ink jet recording method described, for example, in Japanese Laid-Open Patent Application No. 54-59336 (the so-called bubble jet recording method) is such that heat energy is caused to act on ink and the ink subjected to the action of this heat energy undergoes a sudden volume change (film boiling phenomenon) resulting from a state change; by this action force, the ink is discharged from a discharge port at the end of a recording head unit, whereby flying ink droplets are formed and adhere to a recording medium to thereby accomplish recording.
The principle of ink droplet formation in such a recording method is that when an electro-thermal converting member is electrically energized, the ink in the heat-acting portion subjected to the action of the heat energy which is ink droplet forming energy undergoes a state change resulting from a sudden increase in volume; that is, the ink in the heat-acting portion causes the creation, growth and contraction of a bubble very momentarily, whereby liquid present between the heat-acting portion and the discharge opening is discharged as an ink droplet.
By repeating such a cycle of creation, growth, contracting and disappearance of the bubble, the ink is subjected to high heat. Therefore, thermally unstable ink is liable to undergo a chemical change and in the heat-acting portion, production and precipitation of insoluble matter may occur and eventually the recording head may become incapable of discharging the ink. Accordingly, to effect recording at a high speed for a long time by the use of such an apparatus, it is very important to improve the stability of the ink and on the other hand, to set the optimum driving conditions corresponding to the ink in the recording head.
FIG. 1
of the accompanying drawings shows variations with time in the surface temperature T of the heat-acting surface when an electrical signal of pulse waveform shown by P is input to a recording head having an electro-thermal converting member and the volume V of a bubble then created. When the pulse-like electrical signal P which is switched on and off is input to the electro-thermal converting member between a time t
0
and a time t
f
, the surface temperature T of the heat-acting surface reaches a maximum temperature T
P
at the time t
f
.
Here, when T
P
is higher than the boiling point of the ink which is in contact with the heat-acting surface, a bubble begins to be created from a time t
B0
at which T=T
B
in the heat-acting portion filled with the ink, and the volume thereof increases with the lapse of time and reaches a maximum volume V
P
at a time t
p
. When the electrical signal P is switched off at the time t
f
, the surface temperature T begins to attenuate gradually and accordingly, the volume V of the bubble decreases and the bubble disappears at a time t
B1
.
In order to ensure that the discharge of ink droplets is effected efficiently and stably in an ink jet recording apparatus, for example, in the bubble jet recording method described above, driving conditions for film boiling such as a voltage, a pulse width and a frequency at which electrical energy is supplied to the electro-thermal converting member, and further, control such as a pre-discharging or pre-heating for effecting stable practical printing, or the recovery operation of the recording head, are programmed in advance in the ink jet recording apparatus. Particularly, in a recording apparatus of the type in which an ink tank storing therein ink to be supplied to a recording head is interchangeable for the apparatus, if use is made of an ink cartridge storing therein ink of another kind which does not match these various set conditions, there will not be obtained an appropriate combination of the characteristics of the ink and the driving conditions and therefore, normal driving of the recording head cannot be accomplished and recording of high quality will become difficult. For this reason, usually, the form of the ink cartridge interchangeable for the recording apparatus is designed exclusively for each apparatus so that the user may not misuse the ink cartridge.
An example of the form of such an ink cartridge is a box-like form. The ink cartridge is designed so that by the operation of mounting the ink cartridge on a cartridge mounting portion, a hollow needle provided on the mounting portion is thrust in the rubber plug of the cartridge so that the ink may be supplied from an ink containing portion in the cartridge to an ink supply system through the hollow needle.
However, the conventional ink jet recording apparatus having such an interchangeable ink cartridge only permits the use of ink fit for the discharge conditions set in that apparatus, and cannot select ink of different discharge conditions; the range of use of the ink jet recording apparatus is therefore limited and a wide range of use of ink jet recording apparatus having an excellent recording characteristic has been difficult. Also, even if ink having more excellent discharge and recording characteristics is developed in the future, it will become impossible to use such ink or obtain satisfactory printing with the apparatus, because the program in the apparatus is not proper.
The above-noted problems will hereinafter be discussed specifically and in detail. Some examples of typical ink compositions usable in an ink jet recording apparatus are shown in Table 1 below.
TABLE 1
Kinds of ink/
component
#1
#2
#3
Water [%]
50
50
80
DEG [%]
47
37
17
PEG [%]
0
10
0
Dyestuff [%]
3
3
3
Ink #1 is an example of standard ink which exhibits a popular performance in both viscosity and solidification. On the other hand, ink #2 is ink in which the percentage of the component difficult to volatilize is increased relative to the ink #1; relative to ink #2, ink #1 is characterized by a difficulty in clogging the discharge ports of the recording head. Thus, an ink jet recording apparatus using the ink #2 does not require a mechanism for preventing the clogging of the discharge ports during the downtime of the ink jet recording head, so that it can be structurally simplified. However, since the ink #2 has relatively high viscosity, it is necessary that discharge of the ink which does not contribute the recording, i.e., an operation called preliminary discharge, be sufficiently performed in advance in the early stage of each use. This may sometimes lead to a reduced throughput. Also, the ink #2 suffers from a disadvantage in that the ink readily blurs on the recording medium so that a very high quality of printing cannot be provided. Ink #3 is ink characterized in that the percentage of water content is increased relative to the ink #1 and the desiccation of the ink on the recording medium is quick, so that recording of high quality suffering much less from blurring can be accomplished. Further, the ink #3 has a feature in that it can be driven at a relatively high frequency because it permits quick refilling of the nozzle after discharge. However, the ink #3 is readily desiccated and therefore, the ink in the discharge ports of the recording is readily solidified during the downtime of the recording head. Therefore, it is necessary that the recovery operation, such as pumping and capping operations, be performed frequently during the downtime of the recording head. Particularly, where the ink #3 is used for a recording head of the bubble jet type in which heat energy is utilized as ink discharging energy, stable
Hashimoto Kenichiro
Hiramatsu Soichi
Inoue Hiroyuki
Matsui Shinya
Matsumoto Haruyuki
Canon Kabushiki Kaisha
Do An H.
Fitzpatrick ,Cella, Harper & Scinto
Nguyen Thinh
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