JPH11268264A - Recording head for ink-jet printer and method for printing using this and ink-jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording head for an ink-jet printer by means of which ink droplets can be stably injected. SOLUTION: This invention relates to a recording head for an ink-jet printer. In this case, ink droplets are injected from a nozzle part 1. In addition, an ink room 3 feeds ink to the nozzle part 1. In addition, a piezoelectric element 5 provides a positive or a negative pressure to the ink 2 in the ink room 3 by changing the vol. of the ink room 3. In this case, the piezoelectric element 5 generates a pressure within such a range that does not inject the ink droplets from the nozzle part 1 and then, generates a pressure for injecting the ink droplets from the nozzle part 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head for an ink jet printer, a printing method using the same, and an ink jet printer.

[0002]

2. Description of the Related Art Conventionally, an ink jet printer has a maintenance station, and in order to stabilize discharge, during a maintenance operation, a suction operation by a pump, a wiping of a nozzle plate surface by rubber, etc.
Operations such as flushing by discharging ink droplets from all nozzles have been performed.

Further, since many inks use water-based inks, it is inevitable that the ink on the ink tip face of the nozzle portion dries, and the ink composition on the tip face changes within several seconds to several tens of seconds. For example, since the viscosity of the ink increases, conventionally, in order to solve the problem of the instability of ejection during printing, a flushing operation is performed to stabilize the ejection of ink droplets.

[0004]

However, when small droplets are ejected in order to improve the resolution, the ink composition changes at the tip of the nozzle and the viscosity increases, so that the nozzle is stable. There is a problem that the ink is not ejected to the nozzle.

In the case where a pressure generating means is used for ejecting ink droplets, it has been desired to simplify the electric circuit in order to reduce the chip area and reduce the cost.

The present invention has been made in view of the above problems, and provides a recording head for an ink jet printer capable of stably ejecting ink droplets, a printing method using the same, and an ink jet printer. The purpose is to: Further, the present invention provides a recording head for an ink jet printer, a printing method using the same, and an ink jet printer capable of stably ejecting ink and simplifying an electric circuit of a pressure generating unit. With the goal.

[0007]

SUMMARY OF THE INVENTION A recording head for an ink jet printer according to the present invention comprises a nozzle portion for discharging ink droplets, an ink chamber for supplying ink to the nozzle portion, and a volume of the ink chamber which is changed. In a recording head for an ink jet printer having pressure generating means for applying a positive or negative pressure to the ink in the ink chamber, the pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle portion, and then generates the pressure from the nozzle portion. This is to generate pressure for ejecting ink droplets.

Further, the printing method using the recording head for an ink jet printer according to the present invention is characterized in that a nozzle portion for discharging ink droplets, an ink chamber for supplying ink to the nozzle portion, and a volume of the ink chamber are changed. In a printing method using a recording head for an ink jet printer having a pressure generating means for applying a positive or negative pressure to the ink in the ink chamber, the pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from a nozzle portion, This is to generate pressure for ejecting ink droplets from the nozzle portion.

The ink jet printer of the present invention has a nozzle for discharging ink droplets, an ink chamber for supplying ink to the nozzle, and a positive or negative ink in the ink chamber by changing the volume of the ink chamber. In an ink jet printer having a recording head having a pressure generating means for applying a negative pressure, the pressure generating means generates a pressure in a range that does not cause an ink droplet to be ejected from a nozzle portion, and then causes the nozzle portion to eject an ink droplet. To generate pressure.

According to the present invention, the pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle portion,
After that, pressure is generated to cause ink droplets to be ejected from the nozzles, and the ink that is present on the ink tip surface and evaporates and has high viscosity is mixed with the ink in the ink chamber to lower its viscosity. I do.

The recording head for an ink jet printer according to the present invention further comprises a nozzle for discharging ink droplets;
A recording head for an ink jet printer having an ink chamber for supplying ink to a nozzle portion, wherein the recording head for the ink jet printer applies positive or negative pressure to ink in the ink chamber by changing the volume of the ink chamber. And at least one of the pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle portion, and the remaining at least one pressure generating device causes ink droplets to be ejected from the nozzle portion. To generate pressure.

Further, according to the present invention, there is provided a printing method using a recording head for an ink-jet printer, which uses a recording head for an ink-jet printer having a nozzle portion for discharging ink droplets and an ink chamber for supplying ink to the nozzle portion. In the method, a recording head for an ink jet printer has a plurality of pressure generating means for applying a positive or negative pressure to ink in an ink chamber by changing a volume of the ink chamber, and at least one of these pressure generating means includes: A pressure within a range in which ink droplets are not ejected from the nozzle portion is generated, and at least one remaining pressure generating means generates pressure for ejecting ink droplets from the nozzle portion.

Further, according to the present invention, there is provided an ink jet printer including a recording head having a nozzle portion for discharging ink droplets and an ink chamber for supplying ink to the nozzle portion, wherein the recording head for the ink jet printer is provided. A plurality of pressure generating means for applying positive or negative pressure to the ink in the ink chamber by changing the volume of the ink chamber;
One pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle portion, and the remaining at least one pressure generating means generates pressure for causing ink droplets to be ejected from the nozzle portion.

According to the present invention, at least one of the plurality of pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle portion, and the remaining at least one pressure generating means generates the pressure within the range of the nozzle. By generating pressure for ejecting ink droplets from the part, the ink present on the ink front end surface and evaporating and having a high viscosity is reduced by mixing with the ink in the ink chamber, The stabilizing signal input to the stabilizing piezoelectric element can be controlled to be turned on only at the time of printing, regardless of the printing data.

[0015]

Embodiments of the present invention will be described below. First, an example of an embodiment of the invention relating to a recording head for an ink jet printer will be described with reference to FIGS. FIG. 1 schematically shows a recording head for an inkjet printer according to the present invention. In FIG. 1, a nozzle portion 1 is for ejecting ink droplets when printing on paper or the like, and has a very important configuration in a recording head for an ink jet printer. In addition, the surface of the ink 2 to be discharged just for printing, that is, the ink front end surface 2a faces the outside in the hole formed in the nozzle portion 1, and is in contact with the outside air.

In FIG. 1, a space provided above the nozzle 1 is an ink chamber 3, which is provided for supplying the ink 2 to the nozzle 1. The ink chamber 3 temporarily stores aqueous ink.

In the upper portion of the ink chamber 3 via the wall, a pressure generating means is provided. The pressure generating means changes the volume of the ink chamber 3 by displacing the piezoelectric element 5 to apply a positive or negative pressure to the ink 2 existing in the ink chamber 3. The pressure generating means is roughly composed of a piezoelectric element 5, a vibration plate 4, and an electric circuit for controlling the displacement of the piezoelectric element.

Here, the piezoelectric element 5 is made of a ceramic or other material, and by applying a voltage in the axial direction of the element or in a direction perpendicular to the axial direction, the piezoelectric element 5 is oriented in the axial direction or in the direction perpendicular to the axial direction. The displacement is transmitted to the diaphragm 4. In addition,
The piezoelectric element 5 has various types such as a single layer type and a laminated type, but is not limited to a certain range.
Various types can be employed.

The vibration plate 4 applies the displacement generated in the piezoelectric element 5 to
The ink chamber 3 is made use of the elastic property of the diaphragm 4 itself.
Is transmitted as a form of pressure. In this case, depending on the direction of displacement of the piezoelectric element 5, the vibration plate 4 generates a positive pressure on the ink chamber 3, that is, a pressure that works to reduce the volume of the ink chamber, or a negative pressure, that is, a pressure of the ink chamber. Or it can create a pressure that acts to increase the volume. When a positive pressure is generated in the ink chamber 3, the pressure of the ink 2 existing in the ink chamber 3 increases. In order to diverge this pressure, the ink tip surface 2a existing in the nozzle portion 1 Then, an operation of trying to come out to the outside world where the pressure is smaller than the pressure is generated. Conversely, ink chamber 3
When a negative pressure is generated in the nozzle section 1, the ink leading end face 2 a existing in the nozzle portion 1 receives the function of being drawn into the ink chamber 3.

Next, an electric circuit as another configuration of the pressure generating means will be described with reference to FIG. In the figure, an ejection signal generating circuit 11 generates a voltage sufficient to give a necessary displacement of a piezoelectric element 15 in order to generate a pressure required to eject an ink droplet from a nozzle portion 1 of a recording head. Is a circuit for outputting a discharge signal. Further, as described later, the stabilizing signal generation circuit 12 is used to apply a displacement of the piezoelectric element 15 necessary to generate a pressure necessary to prevent the ink tip surface 2a of the nozzle portion 1 from drying. This is a circuit that outputs a stabilizing signal for generating a voltage. Further, the stop signal generation circuit 13
Is a circuit for outputting a stop signal for preventing the displacement of the piezoelectric element 5 when no ejection signal or stabilization signal is required during printing.

In the figure, the above-described ejection signal, stabilization signal, and stop signal are input to a signal switching circuit 14. The signal switching circuit 14 is a circuit that controls which of the input ejection signal, stabilization signal, and stop signal is output. The ejection signal, the stabilization signal, or the stop signal output from the signal switching circuit 14 is output to the piezoelectric element 15.

When a discharge signal or a stabilizing signal is input, the piezoelectric element 15 is displaced in accordance with the input signal. Further, when a stop signal is input, the piezoelectric element 15 does not generate displacement.

Next, the operation of the pressure generating means will be described. Here, a case where the recording head prints one dot will be described. In the electric circuit of FIG. 2, first, the stabilizing signal generating circuit 12 outputs a stabilizing signal having a pulse waveform as shown in FIG. 3B. In FIG. 3B, the stabilizing signal of the pulse waveform generates a positive voltage. This positive voltage signal is input to the piezoelectric element 15 via the signal switching circuit 14. As a result, a displacement occurs in the piezoelectric element 15, and a positive pressure is generated in the ink chamber 3 due to the displacement. Here, the positive pressure generated in the ink chamber 2 is a pressure sufficient to move the ink front end surface 2 a existing in the nozzle portion 1, but a pressure range in which ink droplets are not ejected from the nozzle portion 1. And

That is, in this case, the pressure generating means generates a pressure in a range where the ink droplets are not ejected from the nozzle portion 1. Here, before the ink droplets are ejected, a preliminary vibration is applied to the ink tip surface 2a of the nozzle portion 1 to such an extent that the ink droplets are not ejected. Due to the vibration of the ink front end surface 2a, the ink existing on the ink front end surface 2a is mixed with the ink existing in the ink chamber 3, and a part of the ink that has been in contact with the outside air on the ink front end surface 2a is removed. The ink diffuses into the ink chamber 3 and is replaced by the ink chamber 3
A part of the new ink inside forms the ink front end surface 2a.

Here, the case where a single positive pressure is generated in the ink chamber 3 has been described, but the invention is not limited to the single positive pressure. That is, in addition to this, for example, generating a single negative pressure, a plurality of positive pressures, a plurality of negative pressures, a pair of positive and negative cycles, or a plurality of positive and negative cycles of pressure. Can also. In short, the type is not limited as long as it generates a pressure in a range where the ink droplets are not ejected from the nozzle unit 1. However, when a negative pressure is to be generated, the pressure needs to be large enough to prevent air from entering the ink chamber 3 through the nozzle portion 1.

In FIG. 2, the ejection signal from the ejection signal generating circuit 11 is input to a signal switching circuit 14.
The waveform of the ejection signal is as shown in FIG. 3A. In FIG. 3A, the ejection signal having a pulse waveform generates a positive voltage. This positive voltage ejection signal is input to the piezoelectric element 15 via the signal switching circuit 14. As a result, a displacement occurs in the piezoelectric element 15, and a positive pressure is generated in the ink chamber 3 due to the displacement.

Here, the positive pressure generated in the ink chamber 3 is set to a pressure large enough to eject ink droplets from the nozzle portion 1. That is, in this case, the pressure generating means generates a pressure for discharging the ink droplets from the nozzle unit 1. As a result, ink droplets are ejected from the nozzle unit 1 and reach the object to be printed, for example, paper. In addition, except that the above-described ejection signal or stabilization signal is output from the signal switching circuit 14, a stop signal is output and the piezoelectric element 15 does not displace.

Although the configuration of the piezoelectric element 5, the vibration plate 4, and the electric circuit for controlling the displacement of the piezoelectric element has been described as the configuration of the pressure generating means, the present invention is not limited to this configuration. That is, it is a means for generating a pressure sufficient to cause the ink to be ejected from the nozzle portion 1, and is capable of giving a vibration sufficient to prevent the ink tip surface 2a of the nozzle portion 1 from drying. In addition to these cases, as long as the piezoelectric element can be controlled so as not to be displaced, other configurations can be adopted.

Further, in the above-described example, the case where a single piezoelectric element is used has been described. However, the present invention is not limited to this. For example, by forming a plurality of piezoelectric elements and performing the above-described operation, that is, after at least one piezoelectric element inputs a stabilizing signal and vibrates, at least one other piezoelectric element inputs an ejection signal and discharges ink. Of course, it is possible to adopt a configuration such as generating a pressure for discharging.

Next, a printing method using this recording head will be described. Here, a case where serial printing is performed by a print head having one nozzle will be described. That is, the recording head prints one line for each dot. Next, the paper is fed one line, and the next line is printed in the same manner as above. This is repeated to form an image.

FIGS. 5 and 6 show the state of dots in the case of the conventional method and the state of dots in the case of using the recording head according to the present invention. FIG. 5 schematically shows a printing state by a conventional method. When no printing is performed, no signal for displacing the piezoelectric element is input, and the ejection signal type is input only when printing is performed.

FIG. 4 schematically shows a printing state when the recording head according to the present invention is used. in this case,
When printing is not performed, the ejection signal is not input to the piezoelectric element.However, when printing is performed, a stabilization signal that gives vibrations such as preliminary droplets that do not eject ink droplets is input to several dots that are not printed immediately before printing. , A normal ejection signal is input to the dot following the dot. In the example of this figure, the number of dots for preliminary vibration is 2 dots.

In the case of printing as described above, a stabilizing signal for giving a preliminary dropping vibration to such an extent that ink droplets are not ejected is input to several dots which are not to be printed immediately before, and a normal ejection signal is applied to the subsequent dots. Is input, ink droplets can always be stably ejected. That is, in a state where the normal printing is stopped, the ink tip surface existing in the nozzle portion evaporates and the viscosity of the ink becomes high. At this time, by applying preliminary vibration to the ink front end surface, the ink existing on the ink front end surface is mixed with the ink in the ink chamber, and the viscosity of the ink existing on the ink front end surface is reduced. This makes it easy to eject the ink present on the ink tip surface from the nozzle portion.

As described above, before the ink droplets are ejected from the nozzle portion, by applying a preliminary vibration in a range where the ink droplets are not ejected to the ink tip surface of the nozzle portion,
The ink in the nozzle portion is agitated, and the drying of the ink in that portion can be prevented, and the increase in the viscosity of the ink is suppressed, so that the state of the physical properties of the ink can be constantly maintained. The ink can be ejected, and waste of ink due to flushing can be reduced.

In the above example, the preliminary vibration is two dots. However, the present invention is not limited to this. For example, three or more dots can be used. Here, to enable clear printing, the number of dots can be optimized, but this number is determined by the structure of the recording head, the properties of the ink, and the like. That is, it is determined by the ease with which the ink is mixed and the ease with which the ink dries at the nozzle tip.

Except when the ejection signal is input to the piezoelectric element, a stabilizing signal can be all input to the piezoelectric element. That is, in order to input a stabilizing signal for a certain number of dots before ejecting ink droplets from the nozzles, it is necessary to scan data in advance and detect dots immediately before printing. is there. For this reason, it takes a long time for data processing, and there is a great advantage that the processing is not required if a stabilizing signal is applied to all of the non-printed dots so as to provide a vibration such as a preliminary drop which does not cause ink drops to be ejected.

In the above-described example, an example in which printing is performed by a recording head having one nozzle has been described, but the invention is not limited to this. That is, it is needless to say that the present invention can be applied to a print head having multiple nozzles. That is, the present invention can be applied not only to a print head having one nozzle for printing one line at a time, but also to a print head having multiple nozzles for printing while simultaneously printing several lines.

Next, the case of actually printing by the method using the recording head according to the present invention will be described with reference to FIG. However, it goes without saying that the present invention is not limited to this actually printed example. FIG. 6B shows the result of printing by a conventional method. Here, when not printing, do not input any signal that gives displacement to the piezoelectric element,
The ejection signal is input only when printing.

Here, the recording head moves from left to right in the drawing while printing one line in the vertical direction in the drawing. As can be seen from the figure, when looking at the first part of the print, only a small amount of ink is actually ejected even though the piezoelectric element inputs an ejection signal for each dot. This is because, since there is no preliminary vibration before printing, the ink tip surface existing in the nozzle portion is dried and the viscosity is increased, and ink droplets may or may not be ejected.
However, the number of ejected ink droplets increases as printing proceeds, and ink droplets are ejected from all the dots in the middle. This is because as the printing progresses, the ink that dries and increases in viscosity is ejected and decreases, and at the same time, the ejection pressure acts on the ink tip of the nozzle part many times during printing, so that it is present on the ink tip surface. This is because the pressure of the ink gradually mixes with the ink existing in the ink chamber due to the pressure, so that the viscosity of the ink existing on the ink front end surface decreases and the ink is easily ejected.

On the other hand, the printing state using the recording head according to the present invention has the result shown in FIG. 6A. In this case, when printing is not performed, a signal for displacing the piezoelectric element is not input, but when printing is performed, a stabilizing signal for giving a preliminary dropping vibration that does not eject ink droplets to several dots that are not printed immediately before the printing is input. In addition, a normal ejection signal is input to the subsequent dots. here,
Since the stabilizing signal is input before the ejection signal is input and preliminary vibration is applied to the ink tip surface, the printing is in a clear printing state from the first part.

The printing method using the recording head for an ink jet printer according to the present invention is not limited to paper,
The present invention can also be applied to a film for an overhead projector (OHP) or a cloth. That is, the present invention can be applied in a sufficient range to those to which a general recording head for an inkjet printer can be applied. In addition, it goes without saying that the recording head for an ink jet printer according to the present invention can be applied to all generally existing ink jet printers.

Next, another example of the embodiment of the invention relating to a recording head for an ink jet printer will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 7 schematically shows another example of the recording head for an ink jet printer according to the present invention. In the drawing, a nozzle unit 1 for discharging ink droplets and an ink chamber 3 for supplying ink 2 to the nozzle unit 1 are the same as those in the above-described example.

In the recording head 7 for an ink jet printer of this embodiment, two pressure generating means for applying a positive or negative pressure to the ink 2 in the ink chamber 3 by changing the volume of the ink chamber 3 are provided. It is a feature.
That is, the two pressure generating means displace the respective piezoelectric elements, thereby changing the volume of the ink chamber 3 and generating pressure for the ink existing in the ink chamber 3.

One of the two pressure generating means generates a pressure within a range in which ink droplets are not ejected from the nozzle portion 1. Here, the piezoelectric element and the vibration plate are the same as in the above-described example, and the piezoelectric element may be either a single-layer type or a laminated type. Further, another pressure generating means generates a pressure for ejecting ink droplets from the nozzle unit 1. Here, the piezoelectric element and the diaphragm are the same as those in the above-described example.

Next, an electric circuit which is another configuration of the pressure generating means will be described with reference to FIG. In the drawing, the ejection signal generation circuit 11 is provided in the same manner as in the above-described example.
This circuit outputs a discharge signal for generating a voltage sufficient to give a necessary displacement of the piezoelectric element 15 in order to generate a pressure required to discharge an ink droplet from the nozzle portion 1 of the recording head. . Further, the stop signal generation circuit 13
Is a circuit for outputting a stop signal for preventing the displacement of the piezoelectric element 15 when no ejection signal is required during printing, as in the above-described example.

In the figure, the above-described ejection signal and stop signal are input to a signal switching circuit 14. The signal switching circuit 14 is a circuit that controls which of the input ejection signal and the stop signal is output.

The ejection signal or the stop signal output from the signal switching circuit 14 is input to the piezoelectric element 15. When an ejection signal is input, the piezoelectric element 15 is displaced according to the input signal. When a stop signal is input, no displacement occurs.

In the figure, the stabilizing signal generation circuit 12
Similarly to the above-described example, stabilization for generating a voltage for applying a displacement to the necessary piezoelectric element 16 to generate a pressure necessary to prevent drying of the ink tip surface 2a of the nozzle portion 1 is performed. It is a circuit that outputs a signal. Piezoelectric element 16
When a stabilizing signal is input, a displacement occurs according to the input signal.

Next, the operation of the pressure generating means will be described. In the electric circuit of FIG.
Outputs a stabilized signal having a pulse waveform as shown in FIG. 9B. In FIG. 9B, the stabilizing signal of the pulse waveform generates a positive voltage. This positive voltage signal is input to the piezoelectric element 16. As a result, the piezoelectric element 16 is displaced, and a positive pressure is generated in the ink chamber 3 due to the displacement. The positive pressure generated here is a pressure sufficient to move the ink tip surface 2a existing in the nozzle unit 1,
The range is set so that ink droplets are not ejected from the nozzle unit 1. That is, the pressure generating means generates a pressure in a range where the ink droplets are not ejected from the nozzle unit 1.

As described above, one of the two pressure generating means applies vibration to the ink tip surface 2a of the nozzle portion 1 to such an extent that ink droplets are not ejected. That is, a stabilizing signal for giving a vibration to such an extent that an ink droplet existing on the ink tip surface 2a of the nozzle portion 1 is not ejected to one piezoelectric element 16 is always input during the printing process. The state of the surface 2a is stabilized.

By vibrating the ink tip surface 2a to such an extent that ink droplets are not ejected, the ink present on the ink tip surface 2a is mixed with the ink present in the ink chamber 3, and the ink tip surface 2a As a result, the ink that has been in contact with the outside air diffuses into the ink chamber, and the new ink forms the ink tip surface.

Although the case where a single positive pressure is generated in the ink chamber has been described above, the present invention is not limited to this single positive pressure. That is, in addition to this, for example, generating a single negative pressure, a plurality of positive pressures, a plurality of negative pressures, a pair of positive and negative cycles, or a plurality of positive and negative cycles of pressure. Can also. As described above, the type is not limited as long as it generates a pressure in a range where the ink droplet is not ejected from the nozzle portion. However, when creating a negative pressure,
It is necessary to make the size such that air does not enter the ink chamber 3 through the nozzle portion 1.

The stabilizing signal output from the stabilizing signal generating circuit 12 is constantly generated. That is, the stabilizing signal is output simultaneously when not only the ink droplet is not being ejected but also when the ink droplet is being ejected. Therefore, in this case, the piezoelectric element 16 constantly generates pressure. However, the generated pressure needs to be in a range that does not negatively affect the discharge pressure at the time of printing.

The stabilizing signal output from the stabilizing signal circuit 12 is not limited to the case where the stabilizing signal is constantly generated as described above. That is, for example, it can be generated every other dot, generated every several dots, or output in another pattern. In short, a stabilization signal is generated independently of the ejection signal output from the ejection signal generation circuit 11, and a pressure is generated by the piezoelectric element in accordance with the generated stabilization signal. Any type of stabilizing signal that is sufficient to prevent drying can achieve its purpose.

In FIG. 8, an ejection signal from the ejection signal generation circuit 11 is input to the signal switching circuit 14. The waveform of the ejection signal is as shown in FIG. 9A. In FIG. 9A, the ejection signal having a pulse waveform generates a positive voltage. This positive voltage signal is input to the piezoelectric element 15 via the signal switching circuit 14. As a result, a displacement occurs in the piezoelectric element 15, and a positive pressure is generated in the ink chamber 2 due to the displacement. The positive pressure generated here is a pressure large enough to eject ink droplets from the nozzle unit 1. That is, in this case, the remaining one of the two pressure generating means generates a pressure for ejecting ink droplets from the nozzle portion. As a result, the nozzle unit 1
From there, the ink droplets are ejected and reach the object to be printed, such as paper. Also, a stop signal is output except that the above-described ejection signal is output from the signal switching circuit 14,
The piezoelectric element 15 does not generate displacement.

Although the configuration of the piezoelectric element 5, the vibration plate 4, and the electric circuit for controlling the displacement of the piezoelectric element has been described as the configuration of the pressure generating means, the present invention is not limited to this configuration. That is, the pressure generating means is a pressure generating means sufficient to discharge the ink, and further provides vibration to the ink tip surface 2a of the nozzle portion 1. Further, in these cases, control is performed so that the piezoelectric element is not displaced. Of course, if possible, other configurations can be adopted.

Further, in the above-described example, the case has been described in which there is one pressure generating means for generating a stabilizing pressure and one pressure generating means for generating a discharge pressure. However, the present invention is not limited to this. . For example, there may be two or more pressure generating means for generating stabilizing pressure and / or two or more pressure generating means for generating discharge pressure. That is, there are a plurality of pressure generating means, of which at least one pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle section 1, and the remaining at least one pressure generating means is a nozzle section 1 Needless to say, pressure for ejecting ink droplets may be generated.

As described above, independently of the ejection of the ink droplets from the nozzle portion, the ink in the nozzle portion is agitated by vibrating the ink tip surface of the nozzle portion in such a range that the ink droplets are not ejected. Since the drying of the ink in the portion can be prevented and the increase in the viscosity of the ink can be suppressed, the state of the stable ink physical properties can be always maintained.

With this configuration, the driving of the ejection piezoelectric element is controlled to be on / off based on the same print data as usual, but the stabilization signal input to the stabilization piezoelectric element is output only during printing regardless of the print data. Since control to turn on is sufficient, when a multi-nozzle is used, it can be shared by all the stabilizing piezoelectric elements. Therefore, the driving circuit can be simplified as compared with the case where the stabilizing signal and the ejection signal are switched as in the above-described example. That is, the electric circuit of this example can be simplified as compared with the electric circuit shown in the example of FIG.

As described above, in the present invention, by using two or more pressure generating means, at least one pressure generating means can be used as an auxiliary pressure generating means independent of the discharge pressure generating means. By vibrating the ink at the tip of the nozzle so that no ink droplets are ejected by the auxiliary pressure generating means, the ink at the tip of the nozzle is agitated and the ink at that portion can be prevented from drying, increasing the viscosity of the ink. Therefore, ink can always be stably ejected by the remaining at least one pressure generating means, and waste of ink due to flushing can be reduced.

Further, since the pressure generating means for discharge and the pressure generating means for stabilization are independent, the drive circuit can be simplified. As a result, the number of channels for signal switching is reduced, so that the chip area can be reduced and the cost can be reduced. Further, by separating the ejection piezoelectric element and the stabilization piezoelectric element, the life of the piezoelectric element can be extended as compared with the case where ejection and stabilization vibration are performed by one piezoelectric element.

In the example described above, an example in which printing is performed using a print head having one nozzle has been described. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to a print head having multiple nozzles. It is. That is, the present invention can be applied not only to a print head having one nozzle for printing one line at a time, but also to a print head having multiple nozzles for printing while simultaneously printing several lines. In this case, as described above,
The stabilizing signal can be commonly input to the piezoelectric element that generates the stabilizing vibration, and the advantage of simplification on the circuit can be fully utilized.

Next, a case where printing is actually performed by this method will be described. However, the invention is not limited to this actual example. Printing using the recording head of the present invention has the same result as that described with reference to FIG. 6A.
In this case, when printing, since a stabilizing signal for constantly giving a vibration that does not cause ink droplets to be ejected is input, the printing is in a clear printing state from the beginning.

The printing method using the recording head for an ink jet printer according to the present invention can be applied not only to paper but also to printing paper.
The present invention can also be applied to a film for an overhead projector (OHP) or a cloth. That is, the present invention can be applied in a sufficient range to those to which a general recording head for an inkjet printer can be applied. In addition, it goes without saying that the recording head for an ink jet printer according to the present invention can be applied to all generally existing ink jet printers.

It should be noted that the present invention is not limited to the above-described embodiment, but can adopt various other configurations without departing from the gist of the present invention.

[0066]

The present invention has the following effects. The pressure generating means generates a pressure in a range where the ink droplets are not ejected from the nozzle portion, and then generates a pressure for ejecting the ink droplets from the nozzle portion, so that the ink droplets can be stably ejected. .

Further, at least one of the plurality of pressure generating means generates a pressure within a range in which ink droplets are not ejected from the nozzle portion, and the remaining at least one pressure generating means generates ink pressure from the nozzle portion. By generating the pressure for discharging the ink, the ink can be stably discharged, and the electric circuit of the pressure generating means can be simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an embodiment of the invention relating to a recording head for an inkjet printer.

FIG. 2 is a diagram showing a configuration of an electric circuit used for a recording head for an inkjet printer according to the present invention.

FIG. 3 is a diagram showing waveforms of an ejection signal and a stabilizing signal to be output in an electric circuit of a recording head for an ink jet printer according to the present invention.

FIG. 4 is a diagram schematically showing a printing state when a recording head for an ink jet printer according to the present invention is used.

FIG. 5 is a view schematically showing a printing state when a recording head for a conventional inkjet printer is used.

FIG. 6 is a diagram showing a printing state when printing is actually performed by a method using a recording head according to the present invention, and a printing state when printing is performed by a conventional method.

FIG. 7 is a sectional view showing another example of the embodiment of the invention relating to a recording head for an ink jet printer.

FIG. 8 is a diagram showing a configuration of an electric circuit used in another example of the recording head for an inkjet printer according to the present invention.

FIG. 9 is a diagram showing waveforms of an ejection signal and a stabilizing signal to be output in an electric circuit of another example of a recording head for an inkjet printer according to the present invention.

[Explanation of symbols]

1 nozzle portion, 2 ink, 2a ink tip surface, 3 ink chamber, 4 diaphragm, 5, 6 piezoelectric element, 7 recording head for inkjet printer, 11
{Discharge signal generation circuit, 12} Stabilization signal generation circuit,
13 ‥‥ Stop signal issued

Claims (6)

[Claims] 1. A nozzle for discharging ink droplets, an ink chamber for supplying ink to the nozzle, and a pressure generating means for changing the volume of the ink chamber to apply a positive or negative pressure to the ink in the ink chamber. A recording head for an ink jet printer comprising: a pressure generating unit that generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle unit, and then generates a pressure that causes the nozzle unit to eject ink droplets. A recording head for an ink-jet printer, comprising: 2. A recording head for an ink jet printer, comprising: a nozzle for discharging ink droplets; and an ink chamber for supplying ink to the nozzle, wherein the recording head for the ink jet printer changes the volume of the ink chamber. Pressure generating means for applying a positive or negative pressure to the ink in the ink chamber, wherein at least one of the pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle portion. Wherein at least one of the pressure generating means generates a pressure for ejecting ink droplets from the nozzle portion. 3. A nozzle unit for discharging ink droplets,
A printing method using an ink jet printer recording head having an ink chamber for supplying ink to a nozzle portion and pressure generating means for applying a positive or negative pressure to ink in the ink chamber by changing the volume of the ink chamber, The pressure generating means generates a pressure in a range where the ink droplets are not ejected from the nozzle portion, and then generates a pressure for ejecting the ink droplets from the nozzle portion. Method. 4. A nozzle unit for discharging ink droplets,
In a printing method using a recording head for an ink jet printer having an ink chamber for supplying ink to a nozzle portion, the recording head for an ink jet printer is characterized in that a positive or negative pressure is applied to ink in the ink chamber by changing the volume of the ink chamber. And at least one of these pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle portion, and the remaining at least one pressure generating device generates pressure from the nozzle portion. A printing method using a recording head for an ink jet printer, which generates pressure for discharging ink droplets. 5. A nozzle for discharging ink droplets,
An ink jet printer comprising a recording head having an ink chamber for supplying ink to a nozzle portion and pressure generating means for applying a positive or negative pressure to ink in the ink chamber by changing the volume of the ink chamber. An ink jet printer characterized in that the means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle portion, and then generates pressure for causing ink droplets to be ejected from the nozzle portion. 6. A nozzle unit for discharging ink droplets,
An ink jet printer having a recording head having an ink chamber for supplying ink to a nozzle portion, wherein the recording head for an ink jet printer applies positive or negative pressure to ink in the ink chamber by changing the volume of the ink chamber. A plurality of pressure generating means, wherein at least one of the pressure generating means generates a pressure in a range that does not cause ink droplets to be ejected from the nozzle portion; An ink jet printer that generates pressure for discharging ink.