JPH0664161A - Ink particle formation in ink jet printer - Google Patents

Abstract

PURPOSE:To provide an ink particle formation device that can produce ink particles stably, and to make such device free from restriction of sizes and loss of uniformity even though it is manufactured by pass-production method. CONSTITUTION:In an ink particles formation method for an ink jet printer equipped with a nozzle 7 that ejects pressurized ink liquid, a heat-generating device 10 is provided to the front end of the nozzle 7. Then, heating by the heat-generating device for raising the temperature of the ink liquid ejected out of the nozzle to 80-100 deg.C is repeated, and pulsating flow is formed in the part of liquid column in accordance with variation of viscosity brought about by repetition of the heating, and thereby ink particles are formed continuously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming ink particles for an ink jet printer, in which a pressurized ink liquid is continuously ejected from a nozzle to obtain an image by using the ink particles formed from a liquid column portion.

[0002]

2. Description of the Related Art There is a conventional ink particle forming method for an ink jet printer which uses a drop generator as shown in FIG. 3, and the drop generator vibrates piezoelectrically by a power source 8 having a frequency corresponding to a particle generation frequency. The piezoelectric vibrator 1, the vibration plate 2 for transmitting the vibration of the vibrator 1, and the ink liquid supplied from the ink supply port 4 are set to a length of n / 4λ (λ is a vibration wavelength) in order to create a resonance condition. The ink chamber 9 (formed in the body 3) and the orifice plate 6 having the nozzle 7 and attached to the body 3 via the sealing material 5. In the above configuration, when the piezoelectric vibrator 1 vibrates (for example, hundreds of tens of kilohertz), the ink column (ink chamber 9) ejected from the nozzle 7 is ejected.
The liquid pressure at (3) is, for example, 3 Kg / cm ² ) to which vibration is transmitted to form particles. The formed ink particles are deflection-controlled through a charging electrode and a deflection electrode (both not shown), and printing is performed on the recording paper. Furthermore, Japanese Patent Publication No. 54-13783 discloses an ink particle forming method for an ink jet printer in which a pressurized ink liquid is ejected from a nozzle and ink particles are continuously formed from a liquid column portion of the ejected ink liquid. A heating element is provided at the tip of the nozzle, the heating element repeatedly heats the liquid column portion of the ink liquid, and pulsation is caused in the liquid column portion due to the decrease in the surface tension due to the repeated heating. It has been proposed to form particles continuously.

[0003]

However, according to the former inkjet drop generator, if air bubbles are generated in the ink chamber, transmission of vibration is impaired.
Particle formation becomes unstable, and because resonance conditions must be created and small vibration energy must be effectively used,
Due to dimensional restrictions, there is a limit to miniaturization, and because the vibration output fluctuates depending on how the piezo vibrator is attached, there is a risk of loss of uniformity of characteristics when mass-produced. Further, the latter method of forming ink particles is a method of utilizing the decrease in surface tension due to heating of the liquid column portion of the ink liquid, and only shows that water of 20 ° C. is heated to 30 ° C. , The surface tension at this time is 72.75 dyn / c
There is only about 2.3% reduction from m to 71.18 dyn / cm. This is a phenomenon which is almost the same as the reduction of the liquid column into particles due to the disturbance of the surface tension, and it is supposed that it is difficult to stably form the ink particles having a controlled diameter. The present invention has been made in view of the above, and in order to stabilize particle formation, eliminate dimensional restrictions, and prevent loss of uniformity even in mass production, the viscosity generated by heat generation of the ink liquid The present invention provides an inkjet drop generator provided with a heat generating means for forming particles based on changes.

[0004]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet drop generator applied to the present invention will be described in detail below. FIG. 1 shows an embodiment of the present invention, in which an ink chamber 9 is formed in a body 3 (which can be omitted because a resonance condition is not required), and an ink liquid is supplied to the ink chamber 9 through an ink supply port 4. Done.
The ink chamber 9 has a nozzle 7, and a heating unit 10 such as a laser is provided at the tip of the nozzle 7. In the above configuration, when a driving voltage having a frequency according to the particle generation frequency is applied to the heat generating means 10, the ink liquid heats at the heat generating means 10 portion provided at the tip of the nozzle 7, and the viscosity is lowered. When a laser is used as the heat generating means 10, only the ink liquid can be heated, and the viscosity of the ink liquid ejected from the nozzle 7 can be changed corresponding to the particle generation frequency of 100 to 150 kilohertz. Stable particle formation can be carried out by raising the temperature of the ink liquid to 80 to 100 ° C.

FIG. 2 shows an example in which an ink jet recording apparatus is constructed by using a drop generator applied to the present invention. A pump 22 for pressure-feeding an ink liquid is connected to an ink tank 21, and a pump 22 is provided at a stage subsequent to the pump 22. Is provided with a three-way switching valve 23. A drop generator 20 is provided downstream of the three-way switching valve 23 via a filter 24. Further, a charging electrode 27 for charging the ink particles 26 atomized by the drop generator 20 and a deflection for deflecting the charged ink particles 26 are provided. An electrode 28 is provided. A gutter 29 is provided at the exit side of the deflection electrode 28 to collect the ink particles 26a that go straight without being deflected, and a recording paper 30 is placed at a position to receive the deflected ink particles 26b. Further, another filter 25 is provided between the connection point of the gutter 29 and the three-way switching valve 23 and the ink tank 21. The pump 22, the three-way switching valve 23, the power source of the heat generating means 10 and the deflection electrode 28 are controlled by the control unit 31 via a driver (not shown), and the charging electrode 27 is controlled by the printing control unit (not shown). ) Controlled by. The control unit 31 has an input interface 31a that takes in various signals such as sensor numbers and operation signals into the control unit 31, a ROM 31b that stores a program that processes the input signal, and a CPU 31c that processes various signals based on the program. A RAM 31d for temporarily storing the signal processing result of the CPU 31c, and the CPU 3
It has an output interface 31e that outputs a control signal based on the signal processing result of 1d to a corresponding driver (not shown) to be controlled.

In the above structure, when the printing operation is started, the pump 22 is driven to press the ink liquid from the ink tank 21 into the ink chamber 9 through the three-way switching valve 23 and the filter 24. The ink liquid that has been press-fitted is heated to 80 to 100 ° C. by the heat generating means 10 when discharged from the nozzle 7, and the viscosity is changed to be granulated. When the ink particles 26 are charged by the charging electrode 27, they are deflected by the deflection electrode 28 and fixed on the recording paper 30 (ink particles 26b), and the uncharged ink particles 26a go straight without being deflected. The charging and non-charging of the ink particles 26 are controlled by a print controller (not shown) according to the print signal. Ink particles 26b that have gone straight are gutter 29.
Collected by the ink tank 21 through the filter 22.
Return to.

[0007]

As described above, according to the present invention, the heating element is provided at the tip of the nozzle, and the temperature is 80 to 100, which is sufficient to change the viscosity of the ink liquid and does not vaporize. The ink particles are formed by forming a pulsating flow directly in the liquid column portion of the ink liquid that is continuously ejected by repeating the heating that raises the temperature to ℃. It is possible to stably form the ink particles without the need.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an inkjet recording apparatus configured using an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional inkjet drop generator.

[Explanation of symbols]

3 body, 4 ink supply port, 7 nozzle, 8
Power source, 9 ink chamber, 10 heat generating means.

Claims (2)

[Claims] 1. A method of forming ink particles for an inkjet printer, wherein a pressurized ink liquid is ejected from a nozzle and ink particles are continuously formed from a liquid column portion of the ejected ink liquid, wherein a heating element is provided at the tip of the nozzle. The heating element is repeatedly heated to raise the temperature of the ink liquid when ejected from the nozzle to 80 ° C. to 100 ° C., and a pulsating flow is formed in the liquid column portion based on the change in viscosity due to the repeated heating. A method for forming ink particles for an inkjet printer, characterized in that the ink particles are continuously formed. 2. The method for forming ink particles in an inkjet printer according to claim 1, wherein the heating element is a laser.