JPH06234219A - Method and device for injecting liquid drop - Google Patents

Abstract

PURPOSE:To permit the injection of liquid drops surely and efficiently under a comparatively low voltage by a method wherein rotary field, generated by rotary pulse, is applied on charged liquid in a reservoir to make the liquid to flow accompanying the electrophoresis of charged particles in the liquid. CONSTITUTION:Ink is supplied from an inflow port 4 into a reservoir 5 and a nozzle 6 at all times through a capillary phenomenon to inject the liquid drops of the ink. A negative DC voltage is impressed on an electrode 7 and counter electrodes 10 are grounded while three-phase rotary pulse having a predetermined phase difference is impressed on respective electrodes 8a-8c from respective terminals 9a-9c. Then, positively charged particles in the ink are moved from the electrode 8a, on which the pulse of advanced phase is impressed, to respective electrodes 8b, 8c, on which the pulse of delayed phase is impressed, through electrophoresis. In this case, the ink in the reservoir 5 is transferred to the direction of the nozzle 6 by the impression of the pulse and the ink is injected through the nozzle 5 in liquid drops.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet ejecting method and an apparatus therefor, and is mainly applied to an ink jet printer or the like.

[0002]

2. Description of the Related Art As a liquid drop ejecting device applied to an ink jet printer, a type utilizing mechanical deformation of a piezo element is widely used, but a magnetic force utilizing type or an electrostatic utilizing type has also been developed.

[0003]

In the prior art piezo element utilizing type and magnetic force utilizing type, it is difficult to make the ejecting force applying device for ink thin, and thus it is practically impossible to stack them and electrostatic Although the use type can be thinned, it is necessary to form a high potential difference between the ink and the opposite recording body, which is disadvantageous in that the electrical equipment and safety facilities are complicated and expensive.

Therefore, an object of the present invention is to provide a droplet jetting method which is easy to stack, does not require a high voltage, and is easy to control the jetting of ink, and an apparatus for carrying out the method. It is in.

[0005]

In order to achieve the above object, the present invention applies a multi-phase rotating electric field of three or more phases to a charged liquid to be injected in a storage chamber upstream of a nozzle,
The main feature is that the liquid to be ejected is transported under the electrophoretic action of the rotating electric field and ejected as droplets from the nozzle.

Further, as an apparatus, in addition to providing a reservoir for the liquid to be ejected upstream of the nozzle, a means for charging the liquid to be ejected in the reservoir to a specific polarity is provided, and the liquid to be ejected migrates toward the nozzle. In order to apply the rotating electric field, a large number of sets of electrodes are arranged in a row in the storage chamber wall in a state in which they are sequentially repeated in the downstream direction. The pulse voltage is applied sequentially.

[0007]

The rotating electric field is formed in the flow direction along the reservoir chamber by sequentially applying the rotating pulse of the opposite polarity to the liquid to be injected from the upstream side to the electrodes arranged in parallel in the flowing direction. Due to the electric field, the charged particles of the liquid to be ejected in the storage chamber are sequentially electrophoresed in the downstream direction, so that droplets are ejected from the nozzle in accordance with the application of the rotation pulse, and the rotational electric field is sequentially applied in the upstream direction, thereby ejecting The liquid stops under the tendency of backflow.

[0008]

The present invention will be described in detail below with reference to the accompanying drawings. 1 and 2 are an exploded perspective view and a vertical side view, respectively, showing a nozzle head in which the droplet ejection method of the present invention is applied to an ink jet printer. The lower substrate 1 and the upper substrate 2 are made of glass or the like. In the middle, a thin dielectric flow path member 3 is polymerized and fixed in a sandwiched state.

A thin plate having a thickness of about 0.15 mm is used as the flow path member 3, and the ink inflow path 4 is provided from the upstream side thereof.
Then, the wide storage chamber 5 and the nozzle 6 are sequentially formed to have a depth of about 50 μm in a communicating state.

On the surface of the lower substrate 1, that is, the surface facing the flow path member 3, a charging electrode 7 is formed by vapor deposition or printing at a position corresponding to the inflow path 4 in the flow path member 3. A large number of electrodes 8a, 8b, 8c were formed in a horizontal stripe pattern parallel to the upstream to downstream direction by vapor deposition or printing in a corresponding portion extending over the storage chamber 5 and the nozzle 6 in order, and electrodes in the same phase were connected to each other. The lead terminals 9a, 9b and 9c are connected as they are.

The electrodes 7 and 8a, 8 are formed on the rear surface of the upper substrate 2, that is, on substantially the entire surface of the upper substrate 2 on the side facing the flow path member 3.
Corresponding electrodes 10 facing b and 8c are formed by vapor deposition or printing, and a dielectric layer 11 is formed on the outer surface of the corresponding electrodes 20.
It is formed to a thickness of 150 μm.

A feeding circuit 12 is connected to the electrode 7, and the lead-out terminals 9a, 9b and 9c are connected to the rotation pulse generating circuit 14 with the intervention of the photoelectric switch circuit 13, and the electrode 8a. , 8b, 8c, a rotation pulse as shown in FIG.
It should be possible to apply the voltage in a timely manner under the operation of.

In order to eject the droplets of the ink 15 using the nozzle heads shown in FIGS. 1 and 2, the ink inflow port 4 is connected to an ink tank (not shown). The ink 15 is constantly supplied to the storage chamber 5 and the nozzle 6 by the capillary phenomenon, and the electrode 7 is provided.
For example, a DC voltage of -500 V is applied to the corresponding electrode 10, the corresponding electrode 10 is grounded, and the electrodes 8a, 8b, 8c are sequentially shifted in phase as shown in FIG. 3 via the lead terminals 9a, 9b, 9c. The pulse voltage of +100 V in the state is applied for a short time.

A negative DC voltage is applied to the electrode 7,
Moreover, since the flow path member 3 that is in contact with the electrode 7 is a dielectric, the surface of the ink inflow path 4, that is, the surface that contacts the ink 15, is positively charged, and the ink 15 that has flowed through the ink inflow path 4 is charged. Is positively charged, and the ink 15 in the storage chamber 5 is also positively charged to some extent. When the voltage to be applied to the electrode 7 is selected to be negative, it is desirable to adopt the ink 15 that is easily charged positively and add the charge by friction.

Then, by applying a negative three-phase rotation pulse having a phase difference as shown in FIG. 3 to the electrodes 8a, 8b, 8c arranged in parallel along the storage chamber 5, the pulse of the advanced phase is generated. Positively charged particles in the ink 15 are electrophoresed in the direction of the electrodes 8b and 8c to which a pulse having a delayed phase from the applied electrode 8a is electrophoresed, and the ink 15 itself is subjected to the same state under the accompanying condition. Therefore, the ink 15 in the storage chamber 5 is conveyed toward the nozzle 6 by the application of the rotation pulse, and is ejected from the nozzle 6 as a droplet.

The ejection speed of the ink 15, that is, the carrying speed and the carrying amount can be easily controlled by changing the pulse interval and pulse width of the applied rotation pulse. The ink 15 is stopped by stopping the application of the rotation pulse.
The transport of the ink is stopped, but the ink 15
Partly tends to flow out of the nozzle 6 due to the inertia, and there is a disadvantage that the meniscus formed at the nozzle of the nozzle 6 becomes excessive. Therefore, immediately after the rotation pulse for ejecting the ink 15 is stopped, It is desirable to switch so as to apply a rotation pulse from the downstream to the upstream as shown in 3 to the electrodes 8c, 8b, 8a for an appropriate short time, whereby the ink 15 in the reservoir chamber 5 is temporarily reversed. It is possible to maintain the meniscus at the nozzle orifice of the nozzle 6 in an appropriate state adapted to the next jetting of liquid droplets.

The unit nozzle head constituting the liquid droplet ejecting apparatus of the present invention is suitable for multiple stacking because it can be easily thinned. For example, as shown in FIG. In the same manner as on the surface of the substrate 1, the charging electrode 7 is formed by vapor deposition or the like, and the electrodes 8a, 8b, 8c are formed at the portions corresponding to the storage chamber 5 and the nozzle 6 so that the electrodes of the same phase are mutually connected. The intermediate substrate 16 is manufactured by connecting the lead terminals 9a, 9b and 9c, respectively, while keeping the connection, and the plurality of intermediate substrates 16 and 16 thus constructed, the lower substrate 1 and the upper substrate 2 are formed as shown in FIG. Each of these boards 1, 1
Stacking and fixing the flow path members 3 and 3 in the middle between 6 and 2 and connecting ink tanks of different colors to the ink inflow paths 4 and 4 to adapt to multicolor printing. You can

Further, as shown in FIG. 6, it is easy to form the unit nozzle heads in a laterally arranged manner.
Ink of various colors can be ejected from each of the nozzles 6 and 6 in the parallel state so as to adapt to multicolor printing.

[0019]

As described above, according to the present invention,
A rotating electric field with a rotating pulse is applied to the charged liquid in the storage chamber to cause the liquid to flow by the electrophoresis of charged particles in the liquid, so that liquid droplets can be reliably and efficiently applied under a relatively low voltage. In addition to ejecting the liquid, the ejection speed and ejection amount of the liquid droplets can be easily controlled by controlling the frequency or pulse width of the rotation pulse, and by switching the application order of the rotation pulse in the upstream direction. It is possible to appropriately control the stop of the injection and the meniscus at the injection port. As a means for applying the rotating electric field, power supply to the membrane electrode is sufficient, so that the device itself can be made extremely thin, and high densification by stacking can be easily realized.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a unit nozzle head in a liquid droplet ejecting apparatus of the invention.

FIG. 2 is a vertical cross-sectional side view of a unit nozzle head in the droplet ejection device of the present invention.

FIG. 3 is a time chart of a rotating electric field applied to a unit nozzle head in the liquid droplet ejecting apparatus of the invention.

FIG. 4 is a perspective view of only an intermediate substrate according to another embodiment of the present invention.

FIG. 5 is a perspective view of the droplet ejection device of the present invention in a laminated state.

FIG. 6 is a perspective view of the droplet ejection device of the present invention in which unit nozzle heads are arranged in parallel.

[Explanation of symbols]

 5 Storage Chamber 6 Nozzle 7 Electrode 8a Electrode 8b Electrode 8c Electrode 10 Corresponding Electrode 13 Switch Circuit 14 Rotation Pulse Generation Circuit

Claims (4)

[Claims] 1. A nozzle which conveys the liquid to be injected under the electrophoretic action of the rotating electric field by applying a rotating electric field of three or more phases to the charged liquid to be injected in the storage chamber upstream of the nozzle in the downstream direction. A method for ejecting droplets, characterized in that the droplets are ejected as droplets. 2. The droplet ejection method according to claim 1, wherein immediately after the application of the rotating electric field in the downstream direction is stopped, the rotating electric field in the upstream direction is applied to brake the flowing liquid. 3. A storage chamber for the liquid to be ejected is provided upstream of the nozzle, and electrodes for applying a rotating pulse in a parallel state adapted to the flow of the liquid to be ejected in the direction of the nozzle along the storage chamber and the electrodes facing the electrode. A droplet jetting device, characterized in that an electrode is provided, and a rotating pulse generating circuit is connected to the rotating pulse applying electrode through a switch circuit. 4. The liquid droplet ejecting apparatus according to claim 2, wherein an electrode for charging the liquid to be injected to a specific polarity is provided on an upstream side or a portion near the upstream of the storage chamber for the liquid to be injected.