Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1998-03-05
2001-10-30
Beatty, Robert (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S017000, C347S060000
Reexamination Certificate
active
06310636
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to an ink jet recording method, apparatus and recording head using thermal energy.
In conventional ink jet recording machines, various controls are effected for the purpose of stabilizing the ink ejecting direction (accuracy in the record spot) and stabilizing the ejection amount (Vd (P1/dot)) in order to minimize the image density variation or non-uniformity in the recorded image or the like.
The controls include controlling the ink temperature (temperature control) and controlling ink viscosity which is influential to the ink ejection amount. In the type of the recording apparatus in which a bubble is formed in the ink by thermal energy, and the ink is ejected by the expansion of the bubble, the bubble creating conditions or the like are controlled to stabilize the ejection amount. As for the specific structures for the ink temperature control, the use is made with a heater (exclusively for this purpose or an ejection heater commonly used for this purpose) for heating the recording head containing the ink and a temperature sensor for detecting the temperature relating to the recording head. The temperature detected by the temperature sensor is fed back to the heater. As an alternative, the temperature feedback is not effected, and the recording head is simply heated by the heater.
The heater and the temperature sensors may be mounted on a member constituting the recording head or on an outside portion of the recording head.
For another method for the control of the ejection amount or the like or a method usable with the above-described method, there is a method in which a pulse width of a single pulse (heat pulse) applied for the purpose of production of the thermal energy to an electrothermal transducer (ejection heater) for producing the thermal energy in the above-described type of ejection, so that the quantity of the generated heat is controlled to stabilize the amount or quantity of ejection.
The types of the control are classified in the following four groups:
(1) The head temperature control is carried out at all times (outside
eighborhood) with the temperature feedback;
(2) The head temperature control is carried out if necessary (outside
eighborhood) with the temperature feedback;
(3) The high temperature head control (higher than the ambient temperature) is carried out with the temperature feedback; and
(4) Pulse width modulation of a single heat pulse.
In group 1, since the recording head temperature is always controlled, the evaporation of the water content of the ink due to the heating is promoted. Therefore, increase or solidification of the ink in the ejection outlet of the recording head may be brought about with the possible result of deviation of the ejection direction or the ejection failure. In addition, the density change or non-uniformity may result due to the relatively high dye content in the ink. They ultimately degrade the image quality. Another influence by the continuous heating by the heater is the change in the head structure and the deterioration of the material constituting the recording head with the result of decrease in the reliability and durability of the recording head. Generally speaking, this control is easily influenced by the change in the ambient temperature and the self temperature rise due to the printing operation. More particularly, the ejection amount varies with the result of density variation or non-uniformity.
In group 2 system, the temperature control operation is carried out if necessary, and therefore, it is an improvement of group 1 type. However, since the temperature control is carried out after the printing instruction is produced, the predetermined temperature is required to be reached in a relatively short period, and therefore, large energy (heat generating quantity (W) of the heater) is required for the heating. This results in increase of the temperature ripple increase in the temperature control with the result of impossibility of correct temperature control. If this occurs, the ejection quantity may change due to the temperature ripple with the result of image density variation or non-uniformity. If an attempt is made to correctly effect the temperature control, it is required that the energy supply is reduced. If this is done, the time required for reaching the target temperature becomes longer, and the waiting period for the start of the printing increases.
In group 3 system, the target temperature is made higher than the ambient temperature so as to avoid the influence of the temperature change due to the ambient temperature change or the self temperature increase due to the printing operation. By this, it is possible to reduce the variation in the ejection quantity of the ink during the printing of low duty. However, in the high duty printing operation, for example in a solid black printing, the influence of the temperature rise cannot be avoided since the temperature rise due to the printing is high.
As for a temperature control, the temperature outside the recording head may be controlled. This is advantageous in that the influence of the ambient temperature can be reduced. However, the response to the self temperature rise is not satisfactory, and therefore, it is easily influenced by the self temperature rise.
If the temperature control in the neighborhood of the recording head is carried out, for example, by mounting the heater or the temperature sensor on an aluminum plate functioning as a base plate for supporting the heater board having the ejection heater, then, the response is improved and is effective against the temperature rise due to the printing. However, since the thermal capacity-of the base aluminum plate is large, the temperature ripple results. Because of the temperature ripple, the ejection quantity may vary.
In group 4 system, a pulse width is modulated using a single pulse. However, it is considered that a further improvement is required in order to increase the reproducibility to permit correct ejection amount control from the standpoint of increasing the high image quality, because the controllable range of the ejection amount capable of accommodating the ejection amount variation resulting from the temperature change in the bubble forming ink jet system, and because it is difficult to provide the linearity in the ejection amount with the increase of the pulse width therein.
In addition to the problem of the ejection amount variation, the problem resulting from the self-temperature rise of the recording head is that ejection property variation during the printing due to the ink temperature variation is brought about and that the controlling property variation is brought about because of the variation in the head structure. These may lead to the variation in the ejecting direction, ejection failure and the refilling frequency reduction. If these occurs, the image quality can be extremely degraded.
Since the ink head cartridge is mass-produced, some variations are unavoidable in the area of the heater board, the resistance, the film structure, the sizes of the ejection outlets or the like formed in a silicone chip through a semiconductor manufacturing process. Therefore, the variations possibly exist in the ink ejection quantities for the ink individual ejection outlets in one recording head and in the performance of the individual recording head.
The variation in the ejection property of the recording head may result in the variation in control properties during the printing as well as the initial ejection quantity of the ink. Among various recording head ejection properties, what is particularly significant in the image formation are variation in the ink ejection quantity of the individual recording heads and the variation in the control property.
Another problem is that a non-uniform temperature distribution is produced depending on the number of nozzles used, with the result of non-uniformity or the like.
More particularly, it is not the fact that the printing operation is effected using all of the nozzles. F
Hirabayashi Hiromitsu
Hirose Masayuki
Koitabashi Noribumi
Matsubara Miyuki
Numata Yasuhiro
Beatty Robert
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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