JPH0451355B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink droplet forming method for an inkjet printer that continuously jets pressurized ink liquid from a nozzle and uses ink particles formed from a liquid column to obtain an image.

A conventional method for forming ink droplets in an inkjet printer uses a drop generator as shown in Figure 1, and this drop generator is connected to a power source 8 whose frequency corresponds to the atomization frequency. Therefore, a piezoelectric vibrator 1 that piezoelectrically vibrates, a diaphragm 2 that transmits the vibration of the vibrator 1, and an n/4 vibrator that is supplied with ink liquid from an ink supply port 4 to create a resonance condition.
It consists of an ink chamber 9 (formed in the body 3) whose length is set to λ (λ is the vibration wavelength), and an orifice plate 6 having a nozzle 7 and attached to the body 3 via a sealing material 5. ing.

In the above configuration, when the piezo vibrator 1 vibrates (for example, at a hundred and several tens of kilohertz), the vibration is transmitted to the ink column discharged from the nozzle 7 (the liquid pressure in the ink chamber 9 is, for example, 3 kg/cm ² ). Particle formation takes place. The formed ink particles are deflected and controlled via a charging electrode and a deflection electrode (both not shown), and are printed on recording paper.

However, with conventional drop generators for ink jets, if air bubbles are generated in the ink chamber, vibration transmission is impaired, making particle formation unstable, and creating resonance conditions that generate small vibration energy. must be used effectively,
There is a limit to miniaturization due to dimensional limitations, and furthermore, the vibration output varies depending on how the piezoelectric vibrator is attached, so there is a risk that uniformity of characteristics will be lost when mass-produced.

The present invention has been made in view of the above, and aims to stabilize particle formation, eliminate dimensional limitations, and
In order to ensure that uniformity is not lost even during mass production,
An object of the present invention is to provide a drop generator for an inkjet, which is provided with a heat generating means that turns the ink liquid into particles based on a change in viscosity caused by heat generation of the ink liquid.

The inkjet drop generator applied to the present invention will be explained in detail below.

FIG. 2 shows an embodiment of the present invention, in which an ink chamber 9 is formed in the body 3 (this can be omitted as resonance conditions are not required), and ink liquid is supplied to the ink chamber 9 through an ink supply port 4. will be held. The ink chamber 9 has a nozzle 7, and a heat generating means 10 such as a laser is provided at the tip of the nozzle 7.

In the above configuration, when a driving voltage of a frequency corresponding to the particle formation frequency is applied to the heat generating means 10, the ink liquid generates heat, causing a decrease in viscosity. Heat generating means 10
When a laser is used as a laser, only the ink liquid can be heated, and the viscosity of the ink liquid ejected from the nozzle 7 can be changed in response to a particulation frequency of 100 to 150 kilohertz. Although the figure shows a schematic diagram in which a semiconductor laser is incorporated in the vicinity of the nozzle, a laser light source may be provided outside the body and an optical system may be assembled to irradiate the ejected ink with light.
Stable particle formation can be achieved by raising the temperature of the ink liquid to 80 to 100°C.

FIG. 3 shows an example of an inkjet recording device configured using a drop generator applied to the present invention, in which a pump 22 for pumping ink liquid to an ink tank 21 is connected and A three-way switching valve 23 is provided. A drop generator 20 is provided downstream of the three-way switching valve 23 via a filter 24, and a charging electrode 27 and a charging electrode 27 are provided to charge the ink particles 26 made into particles by the drop generator 20. A deflection electrode 28 is provided to deflect the ink particles 26 . A gutter 29 is provided on the exit side of the deflection electrode 28 to collect the ink particles 26a that are traveling straight without being deflected, and also collects the deflected ink particles 26a.
Recording paper 30 is placed at a position to receive b. Furthermore, 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 above pump 22, 3-way switching valve 2
3. The power source of the heating means 10 and the deflection electrode 28 are controlled by a control section 31 via a driver (not shown), and the charging electrode 27 is controlled by a printing control section (not shown). . The control unit 31 sends various signals such as sensor numbers and operation signals to the control unit 3.
an input interface 31a to be input into 1;
Store the program that processes the input signal
A ROM 31b, a CPU 31c that processes various signals based on the program, and a RAM 31d that temporarily stores the signal processing results of the CPU 31c.
A corresponding driver (not shown) that is controlled by a control signal based on the signal processing result of the CPU 31d
It has an output interface 31e for outputting to.

In the above configuration, when a printing operation is started, the pump 22 is driven, and the ink tank 2 is supplied to the ink chamber 9 via the three-way switching valve 23 and the filter 24.
Ink liquid is press-fitted from 1. When the ink liquid that has been press-fitted is discharged from the nozzle 7, it is heated to 80 to 100°C by the heat generating means 10, causing a change in viscosity and being turned into particles. 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 (the ink particles 26
b) The uncharged ink particles 26a travel straight without being deflected. Charging and non-charging of the ink particles 26 are controlled by a print control section (not shown) according to a print signal. Ink particles 26 that went straight
b is collected by the gutter 29 and passed through the filter 22
It returns to the ink tank 21 via.

As explained above, according to the present invention, ink particles are formed by directly forming a pulsating flow in the liquid column of ink liquid that is continuously ejected. Ink particles can be stably formed without being affected.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional drop generator for inkjet. FIG. 2 is an explanatory diagram showing one embodiment of the present invention. FIG. 3 is an explanatory diagram of an inkjet recording apparatus constructed using an embodiment of the present invention. Explanation of symbols, 3...Body, 4...Ink supply port, 7...Nozzle, 8...Power source, 9...Ink chamber, 10...Heating means.

Claims (1)

[Scope of Claims] 1. An ink droplet forming method for an inkjet printer in which pressurized ink liquid is ejected from a nozzle and ink particles are continuously formed from a liquid column of the ejected ink liquid, comprising: A heating element is provided in the heating element, and the liquid column portion of the injected ink liquid is repeatedly heated by the heating element, and a pulsating flow is formed in the liquid column portion based on the viscosity change due to the repetition of this heating, and the ink particles are continuously generated. A method for forming ink particles in an inkjet printer, characterized in that ink particles are formed in a consistent manner.