JPH02147344A - inkjet recording device - Google Patents

Abstract

PURPOSE:To reduce a driving energy and to improve the speed of supply of a recording liquid by providing a narrow-path part disposed between electrodes in a pair, as well as a discharge port through which the recording liquid is discharged from a recording liquid channel, and by making the recording liquid discharged by impressing a voltage selectively between the paired electrodes. CONSTITUTION:In a recording head, first, a current is made to flow between electrodes 2 and 3 through a recording liquid 1 by impressing a voltage pulse on one of the electrodes 2 and 3. The surface of the recording head other than the electrodes 2 and 3, which comes into contact with ink 1, has an insulating property, while the electrodes 2 and 3 are connected to a drive circuit. A narrow-path part 7 is provided between the electrodes 2 and 3, and when the cross-sectional area of the narrow-path part 7 is made smaller enough than the surface areas of the electrodes 2 and 3, a current density in the narrow-path part 7 becomes large, the recording liquid 1 being heated by an I<2>R loss and a bubble 8 being generated. The ink 1 is discharged from a discharge port 4 by a change in pressure on the occasion. In order to prevent the occurrence of an electric flow in the ink liquid, the resistance values of an electric resistance R11 in a communication port 11 and an electric resistance R9 in a supply channel 9 are set to be R7<R9+R11 in relation to an electric resistance R7 in the narrow-path part 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording apparatus, and more particularly to the structure of a recording head.

Conventional techniques related to the present invention include the following.

US Pat. No. 3,179,042 has a heater for preheating the ink and an electrode for energizing the ink near the orifice, but this consumes a lot of power and requires a high-voltage switching circuit. Additional equipment such as a preheating section is also required, which increases costs.
Multiplication was particularly difficult.

Furthermore, in Japanese Patent Application Laid-open No. 60-500010, an electrode wire is arranged inside a cylindrical insulating block, another electrode is provided in the same liquid chamber, and a voltage is applied between both electrodes (500 to 1500 V).
), current concentrates on the conductive electrode part and the ink heats up. As a result, in the same way as the ink resistance is reduced, an annular electrostatic force acts at the top from the electrode end to the ink surface to eject an ink droplet. In other words, it applies the principle of energization + static electricity. However, like the case above, this also requires a high-voltage drive device and uses electrostatic force as the ejection force, so it is extremely inefficient due to the arrangement of the electrodes. Ta.

The present invention was made to solve the above-mentioned drawbacks, and by applying electricity to conductive ink, the ink itself generates heat and bubbles, and the pressure change at that time causes the ink to To provide an inkjet recording device that uses a method of ejecting droplets to vaporize ink with small energy and effectively converts the pressure at the time of vaporization into ejection energy, and at this time, performs high-speed printing. Therefore, it is an object of this invention to provide a structure of a recording head that makes it possible to improve the recording liquid ejection frequency.

In order to achieve the above object, the present invention includes a pair of electrodes arranged in a recording liquid flow path and made up of at least two or more electrodes, and a pair of electrodes arranged between the pair of electrodes in the recording liquid flow path. comprising a narrow passage provided therein and an ejection port for ejecting the recording liquid from the recording liquid flow path, and ejecting the recording liquid by selectively applying a voltage between the pair of electrodes; The present invention is characterized in that the supply path and the discharge port are disposed so as to communicate with each other on the same side of the green liquor flow path divided by the narrow path. Hereinafter, the present invention will be explained based on examples.

First, the basic operation of the recording head of the inkjet recording apparatus according to the present invention will be explained based on FIGS. 1(a) to 1(c). In the figure, 1 is conductive ink (recording liquid), 2
and 3 are electrodes, and 4 is a discharge port.

5 is a recording liquid flow path, 7 is a narrow path portion, and 8 is a bubble.

(a) shows the initial state, and by applying a voltage pulse to one of the electrodes 2 and 3, a current flows between the electrodes 2 and 3 through the recording liquid 1. Ink 1 other than electrodes 2 and 3 of the recording head
The surface in contact with the electrode is insulating, and the electrodes 2 and 3 are connected to the drive circuit (
(not shown). In (b), a narrow passage 7 is provided between electrodes 2 and 3, and the cross-sectional area (plane perpendicular to the current direction) of the narrow passage 7 is made sufficiently smaller than the surface area of electrodes 2 and 3. The current density in the narrow path portion 7 increases, and the liquid 1 generates heat due to I''R loss, generating bubbles 8. (C)
The ink 1 is ejected from the ejection port 4 due to the pressure change at this time.

FIG. 2 is a perspective view of a main part of an embodiment of an inkjet recording apparatus according to the present invention, and FIGS. 3(a) to 3(c) are component diagrams of the inkjet recording apparatus according to the present invention. In the figure, 9
is a supply path, and 11 is a communication port.

12 is a recording liquid storage chamber, 13 is a recording liquid recovery chamber, and 14 is a pressurizing means (valve means). The recording liquid flow path 5 is divided by a narrow passage 7, and the electrodes 2 and 3 are arranged so as to sandwich the narrow passage 7. The electrode 3 is a common electrode, and one electrode corresponds to the plurality of recording liquid channels 5. The ejection port 4 and the supply path 9 for supplying the recording liquid 1 to the recording liquid flow path are located on the same side 5 of the recording liquid flow path 5 separated by the narrow path portion 7.
It is located at a. A plurality of supply paths 9 arranged for each recording liquid flow path 5 are further connected to a recording liquid storage chamber 12 via a common liquid chamber 10 . A communication port 11 is arranged on the other side 5b of the recording liquid flow path 5.

Here, when the communication port 11 is open to the atmosphere, it is shown in FIG. 3(,), and when it is connected to the recording liquid storage chamber 12, it is shown in FIG. 3(b). The case of connecting to the collection chamber 13 is shown in FIG. 3(C). In addition, the communication port 11 may be provided with suction or pressurizing means such as a pump, as necessary in each of the cases shown in FIGS. 3(a) to (C) above.
Alternatively, a valve means (14) such as a valve may be installed. The communication port 11 is useful for supplying liquid and removing air during initial recording liquid filling and initial state return operation. The cross-section of the flow path is sufficiently small, and its position is also placed in consideration of the propagation of pressure waves. Note that the current when voltage is applied flows through the narrow path 7 to the electrodes 2 and 3.
Energy loss will occur unless it is arranged so that it flows only between the two. Therefore, for example, in the case as shown in FIG. 3(b), no electrical flow occurs in the ink liquid such as from electrode 2 → communication port 11 → common liquid chamber 10 → supply path 9 → electrode 3. In addition, the resistance values of the electrical resistance R11 at the communication port 11 and the electrical resistance R9 at the supply path 9 should be set so that R7<R9+R11 with respect to the electrical resistance R7 at the narrow passage section 7. In addition, in the case of a multi-configuration, R7 < 2
Set R11.

In addition, even when other flow paths are added, loss can be suppressed by considering the settings in consideration of such electrical flow in the ink liquid.

As is clear from the above description, according to the present invention, the current density is amplified because bubbles are generated in the narrow passages by energization. Also, make it a narrow road.

Since the volume of the recording liquid to be heated is limited to a small volume, it can be heated efficiently. therefore.

A synergistic effect can be produced and driving energy can be reduced (corresponding to claim 1). Further, since the discharge port and the supply path are arranged on the same liquid flow path side separated by a narrow path, they are affected by fluid resistance such as the narrow path and the communication port. : The recording liquid can be supplied without any problem, the supply speed (supply capacity) of the recording liquid is improved, and thereby the recording liquid droplet ejection frequency can be improved (corresponding to claim 2).

Furthermore, when the ejection port supply paths are arranged on different sides separated by a narrow path, the recording liquid is supplied from the supply path after droplet ejection.
It will be delivered to the discharge port via the narrow passage.

(Normally, the fluid resistance in the narrow passage is large, and the supply time is therefore longer.)

[Brief explanation of the drawing]

FIGS. 1(a) to 1(c) are diagrams showing the basic operating principle of the recording head of the inkjet recording apparatus according to the present invention. FIG. 2 is a perspective view of essential parts of an embodiment of an ink jet recording apparatus according to the present invention, and FIG. 3 (a) to (c) are component diagrams of the ink jet recording apparatus according to the present invention. 1... Conductive ink (recording liquid), 2.3... Electrode,
4... Ejection port, 5... Recording liquid flow path, 7... Narrow path, 8... Bubbles, 9... Supply path, 10... Common liquid chamber, 11... Communication Mouth, 12... Recording liquid storage chamber, 13.
. . . Recording liquid recovery chamber, 14 . . . Pressurizing means or valve means. Figure 1 (a) -27: Figure 2

Claims (1)

[Scope of Claims] 1. A pair of at least two electrodes disposed in a recording liquid flow path; and a narrow passage portion disposed between the pair of electrodes in the recording liquid flow path; An inkjet recording apparatus comprising: an ejection port for ejecting recording liquid from the recording liquid flow path, and ejecting the recording liquid by selectively applying a voltage between the pair of electrodes. 2. The inkjet recording apparatus according to claim 1, wherein the supply path and the ejection port are disposed on the same division side of the recording liquid flow path divided by the narrow path portion. .