JPH07164641A - Ink jet printer - Google Patents

Abstract

PURPOSE:To improve productivity and print quality by providing a nozzle having an orifice, a source of drive operating to push ink out of the nozzle and a selecting means to allow ink in the nozzle to be discharged out of the orifice. CONSTITUTION:A base portion 3 comprises an electrode 3a arranged for each dot, a dividing plate 3b, an ink passage 3c by way of which ink 1 in a pressure generating portion 2 passes through the base 3, and a base 3d having an electrode 3a and an ink passage 3c. A top board 49 comprises a common electrode 4a and a top board 4b on which the common electrode is provided. An orifice plate 5 has an orifice 5a given by laser processing. Discharge or nondischarge of ink 1 is controlled by a controller 6 by applying voltage of a pulse form to a piezoelectric device 2b and giving an electric field selectively between the common electrode 4a and the electrode 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer.

[0002]

2. Description of the Related Art FIG. 10 is an overall view of a head portion of an electromechanical conversion type ink jet printer using a piezoelectric element, FIG. 11 is a configuration diagram of one dot of the head portion, and FIGS. It is a figure. 10 to 13, 21 is ink, 22 is an ink chamber having elasticity, 22
a is an ink ejection port, 23 is a piezoelectric element that elastically deforms the ink chamber 22 attached on the ink chamber 22, and 24
Is an ink tank that stores a fixed amount of ink 21, 25 is a controller that controls the ejection / non-ejection of the ink 21 by applying a pulsed voltage to the piezoelectric element 23, and 26 is an ink supply path.

The operation of the ink jet head having the above structure will be described below.

When the controller 25 applies a voltage to the piezoelectric element 23, the piezoelectric element 23 is deformed, the volume of the ink chamber 22 is reduced, and the ink 21 is ejected from the ink ejection port 22a (state of FIG. 12). When the controller 25 reduces the voltage, the volume of the ink chamber 22 returns to its original value (state of FIG. 13).

[0005]

However, in the above-mentioned conventional structure, since the ink chamber 22 is required for each dot, the piezoelectric element 23 must be attached on each ink chamber 22, and the number of steps is reduced. There was a problem that productivity was so high that it was very large.

Furthermore, since the ejection amount of the ink 21 is different due to variations in the characteristics of the piezoelectric element 23 for each dot,
There was a problem that the print quality was poor.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an ink jet printer having high productivity and improved printing quality.

[0008]

To achieve this object, a nozzle having an orifice, a drive source that operates so as to push the ink in the nozzle to the outside, and the ink in the nozzle from the orifice to the outside. A selection means that enables ejection is provided.

[0009]

With this structure, it is not necessary to provide a driving means for each dot.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial sectional view of a head portion of an ink jet printer according to an embodiment of the present invention, FIG. 2 is an overall view of the head portion of the ink jet printer, and FIG. 3 is a view of the same ink jet printer when ink is not ejected. 6 is a timing chart of a voltage applied to the head portion, FIG. 4 is a timing chart of a voltage applied to the head portion when ejecting ink of the inkjet printer, FIG. 5 is an overall view of the inkjet printer, and FIG.
Is a characteristic diagram of ink used in the inkjet printer, FIG. 7 is a diagram of a substrate portion of a head portion of the inkjet printer, FIG. 8 is a diagram of a top plate portion of the head portion of the inkjet printer, and FIG. 9 is a head of the inkjet printer. It is a figure of the pressure generation part of a part. In FIG. 1, 1 is ink having a high viscosity when the electric field strength is high, and the viscosity is low when the electric field strength is low (see FIG. 6), 2 is a pressure generating portion, and the pressure generating portion 2 is an elastic partition wall 2a. And the partition 2
It is composed of a piezoelectric element 2b which is attached on a and elastically deforms the partition wall 2a, and a side wall 2c. Reference numeral 3 denotes a substrate portion, and the substrate portion 3 is an electrode 3a arranged for each dot, a partition plate 3b for partitioning the dots, and a hole when the ink 1 in the pressure generating portion 2 passes through the substrate portion 3. Ink passage 3c
And a substrate 3d having an electrode 3a and an ink passage 3c. Reference numeral 4 denotes a top plate portion, and the top plate portion 4 includes a common electrode 4a and a top plate 4b provided with the common electrode 4a. Reference numeral 5 is an orifice plate, and the orifice plate 5 is provided with an orifice 5a formed by laser processing or the like. Reference numeral 6 is a controller for applying a pulsed voltage to the piezoelectric element 2b and selectively applying an electric field between the common electrode 4a and the electrode 3a to control ejection / non-ejection of the ink 1. Reference numeral 7 is a substrate 3d and a partition plate 3b. It is a nozzle formed by the top plate 4b and the orifice plate 5. Figure 2
8 is an ink tank for storing a fixed amount of ink 1. In the ink tank 8, dust contained in the ink 1,
An ink filter (not shown) for removing dust and the like is provided. Reference numeral 9 is an ink conduit for guiding the ink 1 in the ink tank 8 to the pressure generating section 2.

The ink 1 in the ink tank 8 flows into the pressure generating portion 2, and further flows from the pressure generating portion 2 into each nozzle 7 composed of the substrate portion 3 and the top plate portion 4. That is, the ink 1 pressurized by the pressure generating unit 2 is evenly sent to each nozzle 7.

Since the viscosity of the ink 1 increases as the applied electric field increases, a strong applied electric field is applied between the common electrode 4a and the electrode 3a in the nozzle 7 where the ink 1 is not ejected. Since the viscosity of the ink 1 in the nozzle 7 is extremely high, the ink 1 does not jump out even if pressure is applied to the ink 1 by the pressure generating unit 2. On the other hand, in the nozzle 7 that ejects the ink 1, by not generating an electric field between the common electrode 4a and the electrode 3a, or by generating a very slight electric field,
Since the viscosity of the ink 1 in the nozzle 7 is extremely low, the pressure is applied to the ink 1 by the pressure generating unit 2, and the ink 1 is ejected from the nozzle 7.

The ink jet printer of this embodiment is
The drive source for ejecting the ink 1 from the orifice 5a is only the piezoelectric element 2b, and whether or not to eject the ink 1 to the outside is provided with another ejection selecting means, which is different from the conventional example. The composition is quite different. In the conventional inkjet printer, since a drive source (piezoelectric element, heating element, etc.) is provided for each nozzle, the print quality is deteriorated due to variations in the characteristics of each drive source. However, in this embodiment, the drive source is 1
Since it is the individual piezoelectric element 2b and the driving means is not provided for each nozzle 7, the characteristic of the driving source does not vary, and the printing quality can be improved.

In FIG. 5, 10 is a carriage for carrying the ink jet head in the main scanning direction, 11 is a guide shaft for guiding the serially reciprocating carriage 10, and 12 is a guide shaft.
Is a recording paper, and 13 is a roller pair that conveys the recording paper 12 in the sub-scanning direction.

The operation of the ink jet printer configured as above will be described. First, the controller 6 alternately applies a voltage to the piezoelectric element 2b to alternately apply a pressure to the ink 1 in the pressure generating portion 2. A voltage is applied to the electrode 3a to the nozzle 7 that does not eject the ink 1, and an electric field of 2 to 3 kV / mm is applied to the nozzle 12. Then, the viscosity of the ink 1 in the nozzle 7 increases and the ink 1 is not ejected (see FIGS. 3 and 6). No voltage is applied to the electrode 3a to the nozzle 7 for ejecting the ink 1, or even if applied, only about 0.5 kV / mm or less is applied. Then, the ink 1 has a low viscosity and is ejected from the nozzle 7 because pressure is applied by the piezoelectric element 2b (FIG. 4).
And FIG. 6). Here, since there is a certain delay in the change in the viscosity of the ink 1 with respect to the change in the applied electric field, the offset time as shown in FIG. 4 may be necessary in some cases.

Further, when the number of nozzles 7 for ejecting the ink 1 at the same time increases, the pressure in the pressure generating portion 2 becomes insufficient,
Since the ejection amount of the ink 1 is reduced and the print quality is degraded,
At the same time, it is preferable to change the voltage applied to the piezoelectric element 2b according to the number of nozzles 7 that eject the ink 1.

That is, the nozzle 7 for ejecting the ink 1
When a constant voltage is always applied to the piezoelectric element 2b regardless of the number of inks, the amount of deformation of the piezoelectric element 2b is constant. When the amount of the ink 1 discharged from the nozzle 7 through the orifice 5a is large and the number of the nozzles 7 ejecting the ink 1 is large, on the contrary, the pressure of the ink 1 causes the number of the nozzles 7 ejecting the ink 1 to be small. Since the pressure becomes lower than that at the time, each nozzle 7 to orifice 5
The amount of the ink 1 discharged to the outside through a is reduced.

Therefore, when the number of nozzles 7 for ejecting the ink 1 is large, the voltage applied to the piezoelectric element 2b is increased to increase the deformation amount of the piezoelectric element 2b. By reducing the voltage applied to the element 2b to reduce the amount of deformation of the piezoelectric element 2b, the amount of the ink 1 ejected from each nozzle 7 is always maintained regardless of whether the number of nozzles 7 ejecting the ink 1 is large or small. It can be kept constant and the printing quality can be improved.

Specifically, the controller 6 uses the ink 1
If the data regarding the number of the nozzles 7 for ejecting the ink is received from an external device (not shown), the controller 6 controls the voltage applied to the piezoelectric element 2b according to the number of the nozzles 7 for ejecting the ink 1. You can do it.

Furthermore, the applied electric field applied to the ink 1 when ejecting from the nozzle 7 may be controlled by the number of nozzles 7 that eject the ink 1. That is, as can be seen from FIG. 6, the lower the applied electric field applied to the ink 1, the lower the ink 1
Since the viscosity of the ink becomes low, the nozzle 7 that ejects the ink 1
The applied electric field applied to the ink 1 when ejecting the ink 1 may be adjusted according to the number of

That is, when the number of nozzles 7 for ejecting the ink 1 is large as in the above, the pressure applied to the ink 1 from the piezoelectric element 2b becomes small and the amount of the ink 1 ejected from each nozzle 7 becomes small. But on the contrary, ink 1
When the number of nozzles 7 for ejecting is small, the piezoelectric element 2b
Therefore, the pressure applied to the ink 1 is increased, and the amount of the ink 1 ejected from each nozzle 7 is increased.

Therefore, when the number of nozzles 7 ejecting the ink 1 is larger than when the number of nozzles 7 ejecting the ink 1 is smaller, the ink 1 is ejected when ejecting the ink 1.
By reducing the applied electric field applied to the nozzles 7, the ejection amount of the ink 1 from each nozzle 7 can be made constant at all times,
The print quality can be improved.

By the above operation, the ink jet head portion mounted on the carriage 10 linearly moves along the guide shaft 11 according to a print signal sent from a computer or the like (not shown), and the carriage 10 moves. The ink 1 is selectively ejected from the nozzle 7 according to the position. The ink droplets adhere to the recording paper 12 conveyed by the roller pair 13 and perform printing on the recording paper 12 in a width of (printing pitch of the nozzles 7) × (number of nozzles H) by one linear movement. This linear movement is performed a predetermined number of times.

The ink 1 is supplied from the ink tank 8 through the ink filter (not shown) through the ink conduit 9 to the pressure generating portion 2 with the printing operation.

Next, a method of manufacturing the ink jet head portion will be briefly described. First, a method of manufacturing the substrate unit 3 will be described. Cleaned electrically insulating substrate 3d (Si
O _2, Al ₂ O _3, etc.) electrodes of each dot by etching on (Au, print Al, Ti, etc.). Next, a photosensitive resist material containing a phenol resin as a main component is formed on the substrate 3d by a spin coater to the thickness of the nozzle 7 and prebaked. A photomask is overlaid on the substrate 3d, exposed by a mask aligner, and then developed.
The width of the nozzle 7 is formed (FIG. 7).

Next, a method of manufacturing the top plate portion 4 will be described. The top plate 4b (SiO ₂ , Al ₂
An electrode (which will become the common electrode 4a) is printed on O ₃ or resin (FIG. 8).

Next, a method of manufacturing the pressure generator 2 will be described. The side wall 2c (molded product of resin or the like) is bonded to one surface of the partition wall 2a having elasticity (stainless steel having a thickness of about 0.1 μm, resin sheet or the like). Piezoelectric element 2b on the other surface
(A material such as a lead zirconate titanate-based material is baked at a high temperature, an electrode is printed, and a polarization treatment is applied) (FIG. 9).

Next, the ink 1 will be briefly described. Up
As described above, a fluid whose viscosity changes according to the electric field strength is generally
Electro-rheological fluid (manufactured by Bridgestone Corporation, Mitsubishi Kasei)
(Manufactured by Co., Ltd.) is used. The component is an electric charge such as silicone oil
Β-Al in the solvent of gas insulating fluid ₂O₃Solid electrolyte particles such as
The child is dispersed. The ink 1 is
A viscous fluid to which a predetermined amount of pigment or the like is added is used.

[0030]

According to the present invention, there are provided a nozzle having an orifice, a drive source which operates so as to push the ink in the nozzle to the outside, and a selection means capable of ejecting the ink in the nozzle from the orifice to the outside. By providing the drive unit, it is not necessary to provide a drive unit for each dot, so that the productivity is good, and moreover, there is no variation in the drive unit, so that the printing quality can be improved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a head portion of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is an overall view of a head portion of an inkjet printer according to an embodiment of the present invention.

FIG. 3 is a timing chart of a voltage applied to the head portion when ink is not ejected from the inkjet printer according to the embodiment of the present invention.

FIG. 4 is a timing chart of the voltage applied to the head portion when ejecting the ink of the inkjet printer according to the embodiment of the present invention.

FIG. 5 is an overall view of an inkjet printer according to an embodiment of the present invention.

FIG. 6 is a characteristic diagram of ink used in an inkjet printer according to an embodiment of the present invention.

FIG. 7 is a diagram showing a substrate portion of a head portion of an inkjet printer according to an embodiment of the present invention.

FIG. 8 is a diagram showing a top plate portion of a head portion of an inkjet printer according to an embodiment of the present invention.

FIG. 9 is a diagram showing a pressure generating portion of a head portion of an inkjet printer according to an embodiment of the present invention.

FIG. 10 is an overall view of a head portion of a conventional inkjet printer

FIG. 11 is a configuration diagram of 1 dot in a head portion of a conventional inkjet printer.

FIG. 12 is an operation explanatory diagram of a head portion of a conventional inkjet printer.

FIG. 13 is an operation explanatory diagram of a head portion of a conventional inkjet printer.

[Explanation of Codes] 1 Ink 2 Pressure generating part 2a Vibration plate 2b Piezoelectric element 2c Side wall 3 Substrate part 3a Electrode 3b Partition plate 3c Ink passage 3d Substrate 4 Top plate part 4a Common electrode 4b Top plate 5 Orifice plate 5a Orifice 6 Controller 7 Nozzle 8 Ink tank 9 Ink conduit 10 Carriage 11 Guide shaft 12 Recording paper 13 Roller pair

Claims (6)

[Claims] 1. A nozzle having an orifice, a drive source that operates so as to push the ink in the nozzle to the outside, and a selection unit that allows the ink in the nozzle to be discharged to the outside from the orifice. Characteristic inkjet printer. 2. An ink whose viscosity changes according to an applied electric field, a nozzle body provided with a plurality of nozzles for accommodating the ink, and an electric field applied to the ink provided inside each of the nozzles. An electrode to be applied, a pressure generating unit connected to each nozzle, and a drive source provided in the pressure generating unit, and the electrode is applied in a state where pressure is applied to the ink in each nozzle by the drive source. An ink jet printer characterized in that the viscosity of the ink is controlled by an electric field applied to the ink. 3. The ink jet printer according to claim 2, wherein the drive source is a piezoelectric element. 4. An ink having a higher viscosity as an applied electric field increases, a nozzle body having a plurality of nozzles for accommodating the ink, and an ink provided inside each of the nozzles. An electrode for applying an electric field, a pressure generation unit connected to each of the nozzles, and a drive source provided in the pressure generation unit, wherein pressure is applied to the ink in each nozzle by the drive source, Decreasing the viscosity of the ink in the nozzle by reducing the electric field between the electrodes in the nozzle to eject the ink,
An inkjet printer, wherein the ink is ejected from the nozzle. 5. The ink jet printer according to claim 4, wherein the pressure applied to the ink is controlled by the drive source according to the number of nozzles that are going to eject the ink. 6. The ink jet printer according to claim 4, wherein the electrode controls the viscosity of the ink when ejecting the ink according to the number of nozzles that eject the ink.