JPS60157870A - Liquid ejector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a print head, in which an auxiliary pressure chamber is provided between a pressure chamber and a pressure generator for pressure transmission, and the pressure chamber is located near a nozzle. The present invention relates to a liquid ejecting device that can be placed in a.

[Prior art and problems]

FIG. 1 is a diagram explaining the operating principle of the liquid ejecting device, and FIG. 2 is a time chart showing the operating waveforms of each part. In Figure 1, A is the nozzle, B is the pressure chamber, C is the flexible wall, and D is the
is an electrostrictive vibrator, E is an ink supply port, F is an ink column, and G is an ink droplet.

FIG. 1 shows the operating principle of a liquid ejecting device used as a print head in an ink jet printer or the like. In FIG. 1, ink is supplied from a separately provided ink tank through an ink supply port F2. The electrostrictive vibrator D& is a piezo crystal of, for example, zircon, titanate, etc., and has a noquimorph structure with the flexible wall C. First, in the initial state, as shown in Figure 1 ( As shown in a), pressure chamber B and nozzle A are filled with ink.At this time, since the internal pressure of the ink tank is set to be slightly negative than atmospheric pressure, the ink at the tip of the nozzle is The meniscus & are concave toward the outside. Under such an initial condition, when a noxoid signal is applied to the electrostrictive vibrator, it becomes as shown in Fig. 1 (b).
As shown in FIG. 2, the flexible wall C suddenly bends toward the inside of the pressure chamber B due to the contraction of the electrostrictive vibrator. Therefore, the internal pressure of pressure chamber B rapidly increases, and the ink inside moves in both directions toward nozzle A and ink supply port E, and the ink that moves toward nozzle A becomes columnar and is pushed out from nozzle A.

As a result, the liquid pressure within the pressure chamber B rapidly decreases, generating a force that pulls back the ink. As a result, the speed of the ink column F ejected from the nozzle A is faster than the ink inside the nozzle A, and as shown in Figure 1C, the ink column F is separated near the nozzle tip and an ink droplet G is formed. be done. Furthermore, since the ink field in pressure chamber B is in a negative state, the ink left behind in nozzle A begins to move toward the pressure chamber, and the ink meniscus is drawn into the inside of nozzle A. It will be done. When the ink returns to pressure chamber B, pressure chamber B
The hydraulic pressure inside becomes positive again. This pressure and the capillary force induced by the tube wall of nozzle A draw the ink back to the vicinity of the opening of nozzle A. After that, the internal pressure of pressure chamber B repeats damped oscillation from positive to negative and from negative to positive, and returns to the initial state (
As mentioned earlier, the internal pressure returns to slightly lower than atmospheric pressure. At the same time, the ink meniscus within the nozzle A also undergoes a damping motion with the initial position as the equilibrium point after the ink droplet G is separated. FIG. 2 shows waveforms of drive pulses, deflection of an electrostrictive vibrator (piezoelectric element), etc.

Generally, in a print head, the tips of the nozzles are arranged with a gap of about 0.15 microns relative to the inner diameter of 50 microns, so the pressure chambers are placed apart from the tips of the nozzles. Therefore, there is a problem that the flow path from the pressure chamber to the tip of the nozzle becomes long, and the loss along the path becomes large.

[Purpose of the invention]

The present invention is based on the above consideration, and an object of the present invention is to provide a liquid ejecting device that shortens the flow path from the pressure chamber to the tip of the nozzle and reduces loss therebetween. be.

[Structure of the invention]

To this end, the liquid ejecting device of the present invention includes a liquid section, a pressure chamber, a nozzle, and a flow path connecting these, and a part of the wall of the pressure chamber is directed in a direction in which the volume of the pressure chamber decreases. In a liquid ejecting device that pressurizes the liquid in the pressure chamber and ejects a predetermined amount of liquid from the nozzle by displacing the pressure chamber, the first part is configured to deform the pressure chamber wall. The device is characterized in that it is provided with a sub-pressure chamber that abuts, and a means for deforming the wall of the sub-pressure chamber to increase the pressure in the sub-pressure chamber. A chamber and a pressure transmission chamber are separated and connected by a flow path with a large flow resistance, and the pressure in the pressure generation chamber is increased by means for increasing the pressure in the subpressure chamber, and the pressure is transmitted to the pressure transmission chamber. The pressure transmission chamber is characterized in that the wall of the pressure chamber is deformed by an increase in the pressure of the pressure transmission chamber.

[Embodiments of the invention] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a diagram showing the configuration of one embodiment of the present invention, and FIG. 4 is a diagram showing the configuration of another embodiment of the present invention. In the figure, 1 is an auxiliary pressure chamber, 2 is an electrostrictive vibrator, 3 is a nozzle, 4.6 and 10
is a flow path, 5 is a pressure chamber, 7 is a liquid part, 8 is a pressure transmission chamber, 9
indicates a pressure generation chamber.

In FIG. 1, a liquid part 7, a pressure chamber 5, and a nozzle 3 are connected by channels 4 and 6, and a sub-pressure chamber 1 is provided which abuts the wall of the pressure chamber 5 as a means for deforming the wall. . Then, the pressure in the auxiliary pressure chamber 1 is changed by the electrostrictive vibrator 2. Next, its operation will be explained.

First, when a predetermined voltage is applied to the electrostrictive vibrator 2 for a predetermined period of time, a bending force is generated between the electrostrictive vibrator 2 and the wall of the sub-pressure chamber 1 which has a bimorph structure, and the sub-pressure chamber decreases the volume of and generates pressure.

This pressure acts on the wall between the auxiliary pressure chamber 1 and the pressure chamber 5, displacing the wall toward the pressure chamber 5, and increasing the pressure in the pressure chamber 5. A part of the liquid in the pressure chamber passes through the flow path 6 and enters the liquid section 7.
The other part reaches the nozzle 3 via the flow path 4 and is ejected as a liquid part.

Next, when the electrostrictive vibrator 20 is de-energized, the previously curved electrostrictive vibrator 2 and sub-pressure chamber 1 are restored to their normal state. At this time, the pressure in the auxiliary pressure chamber 1 also decreases, and the wall between the auxiliary pressure chamber 1 and the pressure chamber 5 also returns to its state before deformation. Therefore, the pressure in the pressure chamber 5 also decreases, and the liquid is returned from the liquid part 7 and the nozzle 3. At this time, a capillary phenomenon acts on the nozzle 3 side, which acts to pull the entire liquid toward the nozzle 3 side, and is replenished by the volume of the liquid particles ejected earlier, returning to the initial state. During this restoration, the liquid moves back and forth between the pressure chamber 5 and the auxiliary pressure chamber 1 and vibrates. Therefore,
FIG. 4 shows another embodiment of the present invention in which the damping of such vibrations is accelerated.

In FIG. 4, the sub-pressure chamber is separated into a pressure generation chamber 9 and a pressure transmission chamber 8, which are connected by a flow path 10 having a large flow resistance. By configuring the sub-pressure chamber in this way, the pressure generated in the pressure generation chamber 9 acts on the wall between the pressure transmission chamber 8 and the pressure chamber 5 through the pressure transmission chamber 8. When the initial state is restored, the liquid moves back and forth between the pressure transmission chamber 8 and the pressure generation chamber 9 and vibrates, but the flow path connecting the pressure transmission chamber 8 and the pressure generation chamber 9 is The large flow path resistance of 10 speeds up the damping of vibrations.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the pressure in the pressure chamber is changed through the auxiliary pressure chamber, so the pressure chamber can be placed near the nozzle without being restricted by the position of the electrostrictive vibrator. I can do it. In addition, a flow path with large flow resistance is provided between the electrostrictive vibrator side of the auxiliary pressure chamber and the pressure chamber side, so the liquid converges quickly and the liquid replenishment and supply movement becomes smooth. This will speed up the refill time. Furthermore, effects such as improved viscosity margin of the liquid and improved temperature characteristics can be obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the operating principle of the liquid ejecting device, Fig. 2 is a time chart showing the operating waveforms of each part, Fig. 3 is a diagram showing the configuration of an embodiment of the present invention, and Fig. 4 is a diagram showing the configuration of an embodiment of the present invention. It is a figure which shows the structure of another Example. A and 3... nozzle, B and 5... pressure chamber, C... flexible chamber and 2... electrostrictive vibrator, E... ink supply port,
F... Ink column, G... Ink droplet, 1... Sub-pressure chamber, 4.6 and 10... Channel, 7... Liquid part, 8...
・Pressure transmission chamber, 9...pressure generation chamber. Patent Applicant: Fujitsu Limited Representative Patent Attorney Yotsube Kyotani

Claims (2)

[Claims] (1) comprising a liquid part, a pressure chamber, a nozzle, and a flow path connecting them, and by displacing a part of the wall of the pressure chamber in a direction in which the volume of the pressure chamber decreases; In a liquid ejecting device that pressurizes liquid in the pressure chamber and ejects a predetermined amount of liquid from the nozzle, a sub-pressure chamber that abuts the wall of the pressure chamber serves as means for deforming the wall of the pressure chamber; A liquid ejecting device comprising: means for deforming a wall of the sub-pressure chamber to increase the pressure within the sub-pressure chamber. (2) A system comprising a liquid part, a pressure chamber, a nozzle, and a flow path connecting them, and displacing a part of the wall of the chamber in a direction in which the volume of the pressure chamber decreases. In the liquid ejecting device that pressurizes the liquid in the pressure chamber and ejects a predetermined amount of liquid from the nozzle, the means for deforming the wall of the pressure chamber includes an auxiliary pressure chamber that abuts the wall of the pressure chamber; , a means for deforming the wall of the sub-pressure chamber to increase the pressure in the sub-pressure chamber is provided, and the sub-pressure chamber is separated into a pressure generation chamber and a pressure transmission chamber to form a flow path having a large flow resistance. means for increasing the pressure in the auxiliary pressure chamber and transmitting the pressure to the pressure transmission chamber by increasing the pressure in the pressure generation chamber; A liquid ejection device characterized in that it is configured to deform a wall of a pressure chamber.