Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1998-07-16
2001-02-27
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06193346
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink-jet recording apparatus. In particular, the present invention relates to an ink-jet recording apparatus which can record a multi-tone image. Further, the present invention relates to an ink-jet recording apparatus in which a driving waveform is applied to non-firing nozzles such that the nozzles do not fire ink thereby.
2. Description of the Related Art
An ink-jet recording apparatus which can be used as an image forming apparatus of a printer, a facsimile machine, a copier or the like is disclosed in Japanese Laid-Open Patent Application No.57-160654, for example. In this ink-jet recording apparatus, variations in diameters of dots can be corrected and/or a multi-tone image can be recorded, as a result of controlling a driving waveform so as to change an ink-firing amount or a dot diameter. In this ink-jet recording apparatus, appropriate pulses are selected from a series of a plurality of voltage pulses, the thus-selected pulses are used for driving an electromechanical transducing device, a plurality of ink drops, the speeds and diameters of which are different from each other, are fired from a nozzle, the thus-fired plurality of ink drops are combined into a single ink drop while the ink drops are flying, the single ink drop hits on a recording medium, and thus, a dot is formed on the recording medium.
Further, Japanese Laid-Open Patent Application No.6-8428 discloses a driving method in which pulse signal outputting means for outputting a plurality of signals, having pulse widths different from each other, in synchronization with a driving signal, and signal selecting means for selecting one signal from the thus-output plurality of signals, are used. Then, the thus-selected signal is used for switching between turning on and turning off of piezoelectric-element driving means during an unsaturated region of the driving signal so that a voltage to be applied to the piezoelectric element is changed. Thus, an amount of an ink drop fired from each nozzle is caused to be fixed.
However, in a recording apparatus such as that disclosed in Japanese Laid-Open Patent Application No.57-160654, in a case where the number of nozzles of an ink-jet head is increased in response to high-integration and high-density in the recording apparatus, because a circuit for selecting pulses is needed for each nozzle, a scale of an entire driving circuit increases, the number of signal wires increases, and the cost therefor increases. Further, a speed of a carriage is increased due to increase in a recording speed, and a period for repetition of dot formation is shortened. As a result, it is difficult to cause successively fired ink drops to be combined to a single ink drop while the ink drops are flying.
Further, in a recording apparatus using a driving method such as that disclosed in Japanese Laid-Open Patent Application 6-8428, because the voltages applied to the piezoelectric elements vary due to variations in transistor-turning-off timings, it is not possible to control the voltages to be applied to the piezoelectric elements in high accuracy. Further, when a driving voltage is controlled, an amount of an ink drop can be increased as a result of increase in the voltage. However, a speed of the ink drop is also increased at the same time. As a result, a point at which the ink drop hits on a recording medium is shifted so that dot-position accuracy is degraded, and/or ‘satellites’ are formed so that image quality is degraded.
Further, in an ink-jet recording apparatus which can be used as an image forming apparatus of a printer, a facsimile machine, a copier or the like, when an ink drop is caused to be fired from a certain nozzle, meniscuses in adjacent nozzles, which are not caused to fire ink drops, respectively (such a nozzle that is not caused to fire an ink drop being referred to as a non-firing nozzle), are in unstable conditions as a result of being affected mechanically or affected by flowing of the ink in the ink-jet head. Thereby, a speed (ink firing speed) Vj of ink fired from the nozzle of the ink-jet head and/or an amount (ink-firing amount) Mj of ink fired from the nozzle of the ink-jet head vary, when each of the adjacent nozzles is then caused to fire an ink drop, and also, a condition in which an ink drop is not fired sufficiently occurs as a result of bubbles being drawn into the nozzle and contained in the ink in the inkjet head.
As a method for eliminating such problems, Japanese Laid-Open Patent Application No.58-62063 discloses a method. In this method, a head in which two pressure-application chambers (ink chambers) are provided so as to face one another is used. In this arrangement, when one pressure-application chamber has pressure applied thereto and thereby an ink drop is fired therefrom, the other pressure-application chamber also has pressure applied thereto but this pressure application is such that an ink drop is not fired thereby.
However, such a method as that disclosed in Japanese Laid-Open Patent Application No.58-62063 can be used only for an ink-jet head having two pressure-application chambers provided so as to face one another.
SUMMARY OF THE INVENTION
The present invention has been devised in consideration of the above-mentioned problems, and an object of the present invention is to provide an inkjet recording apparatus which can form a high-quality image as a result of stabilization of firing of ink drops.
An ink-jet recording apparatus, according to the present invention comprises:
a plurality of nozzles for firing ink drops;
a plurality of pressure-application ink chambers, communicating with the plurality of nozzles, respectively;
a plurality of energy generating elements for generating energy for applying pressure to ink in the plurality of pressure-application ink chambers so as to cause ink drops to be fired from the plurality of nozzles, respectively;
driving-waveform generating means for generating a plurality of driving waveforms for driving the plurality of energy generating elements; and
driving-waveform selecting means for selecting one of the plurality of driving waveforms generated by the driving-waveform generating means for each one of the plurality of energy generating elements in accordance with image information.
In this arrangement, because a plurality of driving waveforms are generated for driving the plurality of energy generating elements, and one of the plurality of driving waveforms generated by the driving-waveform generating means is selected for each one of the plurality of energy generating elements in accordance with image information, it is possible to stably fire ink drops and to perform high-quality recording with a simple circuit arrangement. Thereby, it is possible to easily form a multi-tone image as a result of controlling diameters of dots, and to easily correct variations in diameters of dots.
The image information may be converted into serial nozzle data for selecting nozzles to be driven for each of the plurality of driving waveforms, the serial nozzle data being input to the driving-waveform selecting means.
In this arrangement, because the image information may be converted into serial nozzle data for selecting nozzles to be driven for each of the plurality of driving waveforms, and the driving waveforms are selected in accordance with the serial nozzle data, it is not necessary to specially provide an image information processing portion, and merely a simple circuit arrangement of the driving-waveform selecting means should be provided, when the driving-waveform selecting means is formed to be an IC which is to be loaded in an ink jet head, and, in the circuit arrangement, the number of signal lines for the serial nozzle data does not increase when the number of nozzles increases.
The serial nozzle data may comprise a number of serial nozzle data, the number being equal to or less than the number of the plurality of driving waveforms. Thereby, it is possible to reduce the number of signal lines for the serial data, an
Barlow John
Cooper & Dunham LLP
Ricoh & Company, Ltd.
Stewart Jr. Charles W.
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