JP2785701B2 - Ink jet printer head and driving method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer head for an ink-jet printer, and more particularly to an ink-jet printer head using a piezoelectric element for converting an electric signal into mechanical energy as ink discharging means, and a method of driving the same.

[0002]

2. Description of the Related Art In recent years, non-impact recording methods have attracted attention in that noise during recording is extremely low and high-speed recording is possible. Among them, an ink jet recording method for recording characters, graphics, etc. by ejecting liquid ink droplets from a printer head to eject the liquid ink onto recording paper can perform high-speed recording and does not perform a special fixing process on plain paper. This is an extremely effective recording method that can perform recording by using the inkjet recording method. At present, various ink jet printers using this ink jet recording method have been proposed and commercialized.

Further, this ink jet recording system is
Depending on the ink droplet generating means in the ink jet printer head, it can be classified into an on-demand recording method, a bubble jet recording method, and the like.The following describes a conventional ink jet printer head using the on-demand recording method. This will be described with reference to FIG.

In FIG. 1, a conventional ink jet printer head includes a plurality of pressure chambers 111 (only one is shown in FIG. 6), an ink supply path 112 formed at the rear end of each of the pressure chambers 111, and A housing 110 having a common ink chamber 113 for supplying ink 140 to each of the pressure chambers 111 via these ink supply paths 112;
A diaphragm 120 attached to the opening surface of the housing 110 to form one side wall of the pressure chamber 111, the ink supply path 112, and the common ink chamber 113, and to form a nozzle 114 at the tip of the pressure chamber 111; 12
And a plurality of piezoelectric elements 130 formed on a plurality of piezoelectric displacement portions 130a divided by slits so as to correspond to the respective pressure chambers 111.

Then, each piezoelectric displacement portion 1 of the piezoelectric element 130
A signal line (not shown) is connected to each of the piezoelectric displacement portions 30a. When a driving signal (signal voltage) is individually input to each of the piezoelectric displacement portions 130a via these signal lines, the piezoelectric displacement portions 130a are moved in the pressure chamber 111 direction. The pressure is applied to the vibration plate 120, and the pressurized vibration plate 120 is bent inside the pressure chamber 111, and an appropriate amount of ink droplet is ejected from the nozzle 114 by the pressure at this time.

[0006]

However, in the conventional ink jet printer head shown in FIG.
Since each piezoelectric displacement portion 130a of the piezoelectric element 130 provided on one side wall of the pressure chamber 111 always applies a constant pressure to the pressure chamber 111 to eject ink droplets,
The size and ejection speed of the ink droplets ejected from the nozzle 114 are uniquely determined by the diameter of the nozzle 114 and the shape of the pressure chamber 111.

For this reason, it is difficult to change the size of the ink droplet ejected from the nozzle 114, and there has been a problem that excellent dot gradation recording cannot be performed. In addition, since the ink droplet is ejected by the piezoelectric displacement unit 130a of the piezoelectric element 130 provided only on one side of the pressure chamber 111, when the ink droplet is continuously ejected from one nozzle 114, the control unit receives There is also a problem that the response speed of the piezoelectric displacement unit 130a to a signal is limited, and the ejection speed of the ink droplet cannot be increased.

In Japanese Unexamined Patent Publication No. 3-272856, the side walls of each pressure chamber are formed by the side surfaces of two rod-shaped piezoelectric elements, and a signal voltage is input to these rod-shaped piezoelectric elements, so that both side surfaces of each rod-shaped piezoelectric element are formed. Ink jet printer heads have been proposed in which ink droplets are ejected from nozzles by simultaneously expanding and displacing nozzles. However, Japanese Patent Application Laid-Open
The ink-jet printer head of 272856 is
Since the two rod-shaped piezoelectric elements forming the side walls of each pressure chamber are configured to always simultaneously expand and displace to eject ink droplets, the size of ink droplets ejected from the nozzles is always constant, as in the above-described conventional example. In addition, there is a limit to the ink ejection speed.

The ink jet printer head disclosed in Japanese Patent Application Laid-Open No. 3-272856 has a configuration in which both side surfaces of each rod-shaped piezoelectric element expand and displace with respect to an input signal voltage, so that one rod-shaped piezoelectric element is displaced. Thus, there is a problem that pressure is simultaneously applied to two adjacent pressure chambers, and ink droplets are ejected from nozzles not scheduled to eject ink droplets. For this reason, in the ink jet printer head disclosed in JP-A-3-272856, a plurality of pressure chambers must be set as dummy chambers in which ink is not inserted every other pressure chamber, and there is a problem that the printer head becomes large.

The present invention has been made in view of the above-mentioned problems, and it is possible to easily change the size of ink droplets ejecting from nozzles, thereby enabling excellent dot gradation recording. It is another object of the present invention to provide an ink jet printer head capable of improving the response speed of a piezoelectric element to a driving signal, thereby increasing the ejection speed of ink droplets, and a driving method thereof.

[0011]

According to a first aspect of the present invention, there is provided an ink jet printer head comprising: a plurality of pressure chambers; Oite from a plurality of nozzles in the ink jet printer head to skip each ink droplets, the first and second diaphragms forming two opposite side walls of the pressure chambers, these first and second diaphragm
To have the first and second piezoelectric displacement portion attached respectively
First and second piezoelectric element that, these first and second piezoelectric element
Displacing one or both of the first and second piezoelectric displacement portions of the
A control unit for controlling a pressure applied to the pressure chamber.
Only one of the first and second piezoelectric displacement units
When the nozzle is displaced and when both are displaced
The configuration is such that the size of the ejected ink droplet is made different .

According to a second aspect of the present invention, there is provided a method of driving an ink jet printer head according to the first aspect of the present invention, wherein a normal recording is performed based on a signal from the control unit. Thus, only one of the first piezoelectric displacement portion and the second piezoelectric displacement portion is displaced.
Or both are displaced to eject ink droplets of the same size from the nozzles, and when performing gradation recording, the first piezoelectric displacement unit is controlled based on a signal from the control unit. And only one of the second piezoelectric displacement parts was displaced
Displaces the rear both Luke, or said first piezoelectric displacement portion
After displacing both of the second piezoelectric displacement parts, displace one of them
This is a method of changing the size of the ink droplets ejected from the nozzles.

According to a third aspect of the present invention, there is provided a method of driving an ink-jet printer head according to the first aspect, wherein the first and second piezoelectric displacement units receive signals from the control unit. Input alternately,
The first piezoelectric displacement unit and the second piezoelectric displacement unit are alternately displaced to eject ink droplets from the nozzles.

[0014]

According to the ink jet printer head and the method of driving the same according to the first and second aspects, the first and second piezoelectric displacement portions respectively corresponding to the two opposing side walls of the pressure chamber are controlled by the control portion. one based on a signal from
By displacing only one or both, pressures of different magnitudes are applied to the ink in the pressure chamber, and the size of the ink droplet ejecting from the nozzle can be changed. Ma
The displacement of only one of the first piezoelectric displacement portion and the second piezoelectric displacement portion
By selectively performing both displacements, excellent dot gradation recording can be performed.

According to the ink jet printer head and the method of driving the same according to the first and third aspects, a signal from the control section is alternately input to the first piezoelectric displacement section and the second piezoelectric displacement section. In response to this, the first piezoelectric displacement portion and the second piezoelectric displacement portion are continuously displaced, so that the ink in the pressure chamber can be continuously pressurized, and the ink droplets can be rapidly discharged from the nozzles. Can be skipped.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ink jet printer head and a method of driving the same according to the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional perspective view showing an ink jet printer head according to one embodiment of the present invention.
FIG. 2 is a sectional side view taken along line AA of FIG.

In these drawings, reference numeral 10 denotes a housing, in which a plurality of pressure chambers 20 are provided. The two opposing side walls of each pressure chamber 20 are formed by first and second diaphragms 31 and 32, and outside the first and second diaphragms 31 and 32, the first and second diaphragms 31 and 32 respectively. Two piezoelectric elements 41 and 42 are arranged.

The first and second piezoelectric elements 41 and 42 correspond to FIG.
As shown in FIG.
a and 42a are inserted and divided to form a plurality of first and second piezoelectric displacement portions 41b and 42b, and these first and second piezoelectric displacement portions 41b and 42b form both side walls of each pressure chamber 20. The first and second diaphragms 31 and 32 are respectively attached so as to correspond to them. These first and second piezoelectric displacement units 41b and 42b are connected to a control unit (not shown) via signal lines, respectively, and based on a signal (signal voltage) from this control unit, these first and second piezoelectric displacement units 41b and 42b are connected. The piezoelectric displacement portions 41b and 42b are configured to be displaced separately and independently.

A common ink chamber 60 communicating with an ink supply path 50 provided at the lower end of each pressure chamber 20 is formed below the inside of the housing 10. Further, a plate having a plurality of nozzles 70 communicating with the upper end openings of the respective pressure chambers 20 is mounted on the upper side of the housing 10. Here, the ink supply path 50 and the common ink chamber 6
The two opposing side walls 0 are also formed by the first and second diaphragms 31 and 32 forming each pressure chamber 20.
The ink 80 is filled in the common ink chamber 60, the ink supply path 50, and the interior of each pressure chamber 20.

Next, an embodiment of a method for driving the present ink jet printer head having the above-described configuration will be described with reference to the drawings. First, a method for driving an ink jet printer head according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 4 (a),
FIG. 3B is a front sectional view showing the operation of the method for driving the ink jet printer head according to the first embodiment of the present invention.

When performing normal recording (recording without giving a gradation), the first piezoelectric displacement portion 41b of the first and second piezoelectric elements 41 and 42 and the second piezoelectric One or both of the displacement portions 42b are continuously displaced, and ink droplets of the same size are continuously ejected from the nozzle 70 to perform recording without giving a gradation.

When performing gradation recording, for example, as shown in FIG. 4A, both the first piezoelectric displacement portion 41b and the second piezoelectric displacement portion 42b are simultaneously displaced, After flying the ink droplet 81 of a predetermined size,
As shown in FIG. 4B, gradation recording is performed by displacing only the first piezoelectric displacement portion 41b to reduce the size of the ink droplet 81 protruding from the nozzle 70.

According to such an ink jet printer head of the first embodiment, after displacing one or both of the first piezoelectric displacement portion 41b and the second piezoelectric displacement portion 42b, displacing both or one of them. Thus, different pressures are applied to the ink 80 in the pressure chamber 20 and the nozzle 70
It is possible to easily change the size of the ink droplet 81 protruding from the ink droplet. This makes it possible to perform excellent dot gradation recording.

Next, referring to FIGS. 5A and 5B,
A method for driving the ink jet printer head according to the second embodiment of the present invention will be described. FIG. 5 (a), (b)
FIG. 7 is a front sectional view showing the operation of the method for driving the ink jet printer head according to the second embodiment of the present invention.

In these drawings, in the ink jet printer head according to the second embodiment, signals from the control unit are alternately input to the first and second piezoelectric displacement units 41b and 42b, and the first and second piezoelectric displacement units 41b and 42b are used. Two piezoelectric displacement parts 41b, 4
2b are displaced alternately so that the ink droplet 81
Is a method of continuously flying.

According to the ink jet printer head of the second embodiment, the first and second piezoelectric displacement portions 41b and 42b are continuously displaced based on the signal from the control portion. The ink in the chamber 20 can be continuously pressurized, and the ink droplet 8
1 can fly at high speed.

[0027]

As described above, according to the ink jet printer head and the method of driving the same according to the present invention,
The size of the ink droplet ejected from the nozzle can be easily changed, thereby enabling excellent dot gradation recording and improving the response speed of the piezoelectric element to a driving signal, thereby improving the ink droplet The discharge speed can be increased.

[Brief description of the drawings]

FIG. 1 is a partial sectional perspective view showing an ink jet printer head according to an embodiment of the present invention.

FIG. 2 is a sectional side view taken along line AA of FIG.

FIG. 3 is a perspective view showing a piezoelectric element of the ink jet printer head.

FIGS. 4A and 4B are front sectional views showing the operation of the method of driving the ink jet printer head according to the first embodiment of the present invention.

FIGS. 5A and 5B are front sectional views showing an operation of a method of driving an ink jet printer head according to a second embodiment of the present invention.

FIG. 6 is a side sectional view showing an ink jet printer head according to a conventional example.

[Explanation of symbols]

 Reference Signs List 10 housing 20 pressure chamber 31 first diaphragm 32 second diaphragm 41 first piezoelectric element 42 second piezoelectric element 41a, 42a slit 41b first piezoelectric displacement part 42b second piezoelectric displacement part 50 ink supply path 60 common ink chamber 70 Nozzle 80 Ink 81 Ink drop

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/045 B41J 2/055 B41J 2/205

Claims (3)

(57) [Claims] By 1. A piezoelectric element, Oite the ink filled in the plurality of pressure chamber pressurized, the ink jet printer head to skip each ink droplets from a plurality of nozzles corresponding to these pressure chambers opposes the pressure chambers first and second diaphragm forming two side walls, and first and second piezoelectric elements which have a first and second piezoelectric displacement portion attached respectively to these first and second vibrating plate, these first First and second piezoelectric displacement portions of first and second piezoelectric elements
To control the pressure applied to the pressure chamber by displacing one or both
And a control unit for controlling one of the first and second piezoelectric displacement units.
When the nozzle is displaced only when both are displaced and when both are displaced
An ink jet printer head characterized in that the size of ink droplets ejected from the ink is varied . 2. The method of driving an ink jet printer head according to claim 1, wherein, when performing normal recording, the first piezoelectric displacement unit and the second piezoelectric displacement unit are controlled based on a signal from the control unit. Displacing only one of the displacement units , or displacing both, to eject ink droplets of the same size from the nozzle, and when performing gradation recording, based on a signal from the control unit, , is displaced both after only a displaced one of the first piezoelectric displacement portion and the second piezoelectric displacement portion Luke, there have
Displaces both the first piezoelectric displacement part and the second piezoelectric displacement part.
A method of driving an ink jet printer head, characterized in that the size of an ink droplet ejected from the nozzle is changed by displacing one of the ink droplets after the application. 3. The method for driving an ink jet printer head according to claim 1, wherein a signal from the control unit is alternately input to the first and second piezoelectric displacement units, and the first piezoelectric displacement unit is provided. And a second piezoelectric displacement unit that alternately displaces the ink and ejects ink droplets from the nozzles.