JPH0241253A - inkjet recording device - 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 The present invention relates to an inkjet recording apparatus, and more particularly to a head section of an inkjet recording apparatus.

Ju” 1 branch technique.

7 and 8 are cross-sectional views showing the head section of a conventional inkjet recording apparatus, respectively.

A pair of electrodes 4 and 5 are disposed in an ink pressurizing chamber 3 that communicates with the ink reservoir 1 via a connecting pipe 2, and a discharge between the electrodes communicates with the opposite side of the pressurizing chamber 3 from the ink reservoir. Printing is performed by ejecting ink from the injection port 6 (see Japanese Patent Publication No. 62-9430). is applied, the ink must be insulating and high voltage is required. FIG. 8 shows a pair of electrodes 7 and 8 disposed on the same plane and perpendicular to the ink tube 9, with a gap 10 formed between the two electrodes 7.8. The ends of the electrodes 7.8 are fixed to the tube 9, the gap 10 is immersed in ink 11, and by applying a voltage to both the electrodes 7.8, a spark is generated in the gap 10 between the two electrodes. The ink 11 in the gap 10 is vaporized or ionized, expanded in the direction of the recording paper 12, and ejected from the opening 13 (U, S, P).

3.177.800), in this case as well, the ink is limited to M-edge properties and requires high voltage. There are also some that use conductive ink (Japanese Patent Laid-Open No. 58-3646)
(see Publication No. 2), in this case, the voltage pulse is a high voltage, so there is a drawback that the driving cost is high.

- Kazuma The present invention was made in view of the above-mentioned circumstances,
In particular, this was done with the aim of improving the image quality of printing by using water-based (conductive) ink and reducing costs by lowering the voltage pulse for discharge.

Configuration In order to achieve the above object, the present invention includes a liquid discharge port;
A liquid chamber communicating with the liquid discharge port, a pair of electrodes disposed in the liquid chamber, and a pair of electrodes that generate bubbles in the liquid in the liquid chamber by electrolysis, and then generate the bubbles by electric discharge. a voltage applying means for applying a voltage so as to change the volume of the electrode, or after generating bubbles by electrolysis between a pair of electrodes on at least one of the pair of electrodes, the bubbles are generated by electric discharge. The device is characterized by having a voltage applying means for applying a voltage so as to change the volume of the device. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a sectional view of essential parts for explaining one embodiment of an inkjet recording apparatus according to the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 1, FIG. 3(b) is a current waveform diagram, and FIGS. 4(a) to 4(d) are diagrams showing changes in the volume of bubbles.

20 is a conductive (aqueous) ink, 21 is a nozzle, 22 is a first electrode, 23 is a second electrode, 24 is a bubble, 25 is an interface between the bubble and ink, 26 is an ink supply channel, and 27 is a common liquid chamber. , the first electrode 22 is disposed corresponding to each nozzle 21 of the multi-head, and is connected to an electric circuit (not shown) so that a voltage pulse can be applied to each nozzle individually. The second electrode 23 is composed of one electrode common to each nozzle 21, and is arranged at the tip of the nozzle and connected to the other of each circuit to which the first electrode 22 is connected. The conductive ink 20 is supplied from an ink tank or the like (not shown) to the common liquid chamber 27, and is supplied to the nozzle 21 through each ink supply channel 26. Said 1st and 21st! For the poles 22 and 23, a material such as platinum which is chemically stable and has excellent heat resistance is suitable, and the other head materials are #I edge materials.

3(a) shows the voltage waveform applied to the first electrode 22, FIG. 3(b) shows the current waveform flowing between the first electrode 22 and the second electrode 23, and FIG. 4(a) shows the current waveform flowing between the first electrode 22 and the second electrode 23. - (d) show the state in which the volume of the bubble of the first electrode 22 changes, and (a) and (b) of Fig. 4.

The state of the change in the volume of the bubble shown in each of (c) and (d) corresponds to the current waveform shown by the symbol ■■■■ in FIG. 3(b). That is, by applying electricity between the first electrode 22 and the second electrode 23, as shown in FIG. "Heat generation occurs due to R loss. Next, as shown in FIG. It is electrically insulated and the current supply stops.At this time, the current waveform is shown by ■ in Fig. 3(b).Next, as shown in Fig. 4(c), hydrogen bubbles 2
When the interface 25 between the hydrogen bubble 4 and the ink becomes at the same potential as the second electrode 23 and the electric field strength between the interface and the electrode increases, a discharge is induced in the hydrogen bubble 24. The current waveform in this state is shown by ■ in FIG. 3(b). Next, Figure 4 (d
), the pressure inside the ink supply channel 26 increases due to the heat generated during discharge, the expansion of the hydrogen bubbles 24, and the bubbles caused by the vaporization of the ink, causing the ink 20 to flow from the nozzle 21.
is injected. At this time, as shown by the symbol ■ in FIG. 3(b), the electric field strength decreases due to the expanding bubbles and the discharge stops.

Although the first electrode 22 is set to a positive potential in FIG. 4, it is also possible to set the first electrode 22 to a negative potential to generate hydrogen bubbles on the surface of the first electrode 22. By doing so, discharge at a lower voltage can be achieved. It becomes possible. Further, by providing the first electrode 22 near the nozzle 21, ink can be ejected by bursting the bubbles 24 due to discharge.

5 and 6 are diagrams for explaining other embodiments of the inkjet recording apparatus according to the present invention, respectively. As shown in FIGS. 5(a) and 5(b), the opening of the head is not a nozzle but a slit. Further, as shown in FIG. 6, the position of the second electrode 23 is not limited to the nozzle portion 21 of the ink supply channel 26 as long as it can come into contact with ink.

As is clear from the above explanation, according to the present invention, even conductive ink can be discharged by insulating the electrodes with air bubbles generated by electrolysis, and small air bubbles can be used to connect the first electrode Since it covers the area, a high electric field strength can be obtained even at a low voltage, so it is possible to reduce the applied voltage. or,
By setting the potential of the first electrode to a negative potential (lower potential than the second electrode), it is possible to convert bubbles generated at the first electrode into hydrogen, thereby further lowering the voltage.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part for explaining an embodiment of an inkjet recording apparatus according to the present invention, FIG. 2 is a sectional view taken along line A--A in FIG. 1, and FIG. 3(a) is a sectional view of a main part. 1, FIG. 3(b) is a current waveform diagram, and FIG. 4(a) to (d) are bubbles of the first electrode of the embodiment according to the present invention. FIGS. 5 and 6 are diagrams for explaining other embodiments of the inkjet recording apparatus according to the present invention, and FIGS. 7 and 8 are cross-sectional views showing the conventional example, respectively. be. 21... Nozzle, 22... First electrode, 23... Second electrode. 24... Air bubbles, 25... Interface between air bubbles and ink, 26
... Ink supply channel, 27 ... Common liquid chamber, 28 ...
・Slit-shaped opening. Fig. 1 Fig. 2 → A Goni / 10 N applied voltage - Fig. Fig. Fig. + (7) tb> Fig.

Claims (1)

[Scope of Claims] 1. A liquid discharge port, a liquid chamber communicating with the liquid discharge port, a pair of electrodes disposed within the liquid chamber, and an electric current applied to the liquid in the liquid chamber between the pair of electrodes. An inkjet recording apparatus comprising: voltage applying means for applying a voltage so as to change the volume of the bubbles by electric discharge after generating bubbles by decomposition. 2. A liquid discharge port, a liquid chamber communicating with the liquid discharge port, a pair of electrodes disposed within the liquid chamber, and at least one of the pair of electrodes between the pair of electrodes, by electrolysis. An inkjet recording apparatus comprising a voltage applying means for applying a voltage so as to change the volume of the bubbles by electric discharge after generating the bubbles. 3. The inkjet recording apparatus according to claim 1 or 2, wherein the surface area of one of the pair of electrodes in contact with the liquid is different from the surface area in contact with the other liquid. 4. The inkjet recording apparatus according to claim 1 or 2, wherein the electrode that changes the bubble volume of the pair of electrodes is set at a lower potential than the other electrode.