JPS592618B2 - Inkjet head driving method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a head driving method in an inkjet recording apparatus.

In conventional inkjet recording apparatuses, air was sometimes sucked through the nozzles.

This is because the ink supply pressure is negative, but air is prevented from being sucked in by the surface tension of the nozzle and capillary action. However, when the ejection response frequency is increased, a large amount of negative pressure is applied to replenish the amount of ink that has been ejected in a short period of time, causing a phenomenon in which air is sucked in. or,
Since only the diaphragm for ejection was used, pressure waves were dispersed during pressurization and ink was ejected without concentrating on the nozzle, resulting in poor efficiency. The present invention will be described to provide an inkjet head drive method that eliminates the drawbacks of the head drive method of the conventional inkjet recording apparatus, improves the response frequency, and prevents air from being sucked into the nozzles. Note that the same parts in each figure are given the same numbers.

FIG. 1 is a general view of an embodiment of an inkjet head according to the present invention, FIG. 2 is an exploded view of the inkjet head of FIG. 1, and FIG. 3 is a sectional view. 1 is a head main body, 2 is an electrostrictive vibrator for jetting, 3 is an electrostrictive vibrator for bias, 4 is a diaphragm for jetting, 5 is a diaphragm for bias, 6 is an ink supply port, T is a nozzle, and 8 is a 9 is a bias pressure chamber, 9 is an ejection Calorie pressure chamber, and 10 is an ink droplet.

In addition, the injection electrostrictive vibrator 2 and the diaphragm 4, and the bias electrostrictive vibrator 3 and the diaphragm 5 are bonded, respectively, and the diaphragm 4,
5 is soldered to the main body. The driving method of such an inkjet head of the present invention will be explained with reference to FIG.

FIG. 4a shows a voltage waveform for driving the bias electrostrictive vibrator 3, and FIG. 4b shows a voltage waveform for driving the injection electrostrictive vibrator 2, which is twice that of waveform a. At frequency, waveform a
is added intermittently in synchronization with a during the period of increase in a.
First, the bias diaphragm 5 does not act to form and eject ink droplets, but only acts to form pressure waves and meniscuses.

The injection diaphragm 4 under the action of the bias diaphragm,
An operation is performed to apply enough pressure to form the smallest droplet. In period 1 in Fig. 4, the injection diaphragm is on standby;
The bias diaphragm is in the suction stroke, almost no negative pressure is generated in the nozzle, and the bias pressure chamber is replenished with ink. In period 1', the bias drive voltage increases,
The volume of the chamber 8 is small, and the pressure increases and ink is ejected from the chamber 8 to the chamber 9 during the ejection stroke.On the other hand, the ejection drive voltage decreases, the volume 9 increases, and the pressure decreases during the suction stroke. The increase and decrease in pressure in chambers 8 and 9 cancel each other out, and the negative pressure does not increase. In period 5, the bias drive voltage is increasing further (during the ejection stroke), while the injection drive voltage is also increasing, and the pressures in both chambers 8 and 9 increase, and are combined with each other, Sprays ink droplets with great vigor. In period A, the bias drive voltage increases while the injection drive voltage decreases, so it is similar to period 1'', and the rise and fall in pressure in chambers 8 and 9 cancel each other out, and the negative pressure increases. As described above, according to the present invention, the bias diaphragm acts to feed ink into the ejection pressurizing chamber, and during ejection, the two diaphragms act in combination. When replenishing ink, there is no sudden negative pressure generated in the nozzle, suppressing the air suction phenomenon, and a small ejection drive voltage is sufficient, improving the response frequency and eliminating the dispersion of pressure waves. Injection efficiency can be increased.

[Brief explanation of drawings]

FIG. 1 is an overview of the ICJet head according to the present invention, FIG. 2 is an exploded view of the ICJET head of FIG. 1,
FIG. 3 is a cross-sectional view of the jet head in FIG. 1, FIG. 4a is a voltage waveform diagram for driving the bias electrostrictive vibrator, and FIG. 4b is a voltage waveform diagram for driving the injection electrostrictive vibrator. It is a voltage waveform diagram. 1... Head main body, 2... Electrostrictive vibrator for injection, 3... Electrostrictive vibrator for bias, 4, 5
...Vibration plate, 6...Ink supply port, 7
・・・・・・Tsuzuru, 8...Bias pressurization chamber, 9
...Ejection pressurized chamber, 10...Ink droplets.

Claims (1)

[Claims] 1. A bias pressurization chamber, an injection pressurization chamber connected to the bias pressurization chamber and having a nozzle, a bias vibrator coupled to the bias pressurization chamber, and an injection vibrator coupled to the injection pressurization chamber. In driving an inkjet head equipped with
An alternating current bias drive signal having a constant frequency and amplitude is continuously applied to the bias vibrator to cause a pressure rise and a pressure drop to the extent that a meniscus is formed in the bias pressurization chamber and the injection pressurization chamber connected thereto. Bias pressure is repeatedly applied, and when ink is ejected, during the pressure increase period of the bias pressure, the frequency of the bias drive signal is increased by 2.
An intermittent alternating current ejection drive signal with twice the frequency is applied to the ejection vibrator to generate a combined pressure of ejection pressure and bias pressure in the ejection pressurization chamber, thereby forming ink droplets. An inkjet head driving method characterized by ejecting.