JPH05293963A - Ink jet printing head - Google Patents

Abstract

PURPOSE:To obtain high image quality by stably supplying ink to the surface of an orifice even at the time of high frequency driving and reducing the involution of air bubble. CONSTITUTION:The ink to which energy necessary for emitting ink is applied from a pressure liquid chamber is emitted from the orifice 7 provided to a nozzle plate 9. A liquid dropping preventing barrier wall 5 is provided to the lower part of the nozzle plate 9. In place of the barrier wall 5, the nozzle plate is subjected to hydrophilic treatment and only the lower part thereof is subjected to water repelling treatment to prevent liquid dripping.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an inkjet printer head, and more particularly to a drop-on-demand inkjet printer.

[0002]

2. Description of the Related Art FIGS. 8 (a) and 8 (b) are configuration diagrams for explaining an example of a conventional ink jet head.
(A) is a cross-sectional view of the flow path in the nozzle direction, (b) is a cross-sectional view of the flow path in the nozzle arrangement direction, in which 21 is a substrate, 22 is a laminated piezoelectric ceramics (piezoelectric element), 23 is a flow path plate, Reference numeral 24 is a flow channel (pressurized liquid chamber), 25 is a common liquid chamber, 26 is a common liquid chamber constituent member, and 27 is a piezoelectric element (PZT) electrode of each flow channel.
Reference numeral 28 is a protective plate, 29 is a nozzle plate, 30 is a nozzle, 31 is a printed wiring board (PCB), and 32 is a groove.

The piezoelectric element 22 is grooved as shown in FIG. 8 (b), and the groove 32 is filled with a filler, whereby the piezoelectric element 22 is independent for each flow path 24. It can be driven. That is, the displacement of the convex portion separated by the groove 32 causes the volume of the channel 24 in the corresponding channel plate 23 to change, and ink droplets are ejected from the nozzle 30. The groove 32 is filled with a filler so as not to affect the driving of the adjacent piezoelectric element 22. Further, the groove 32 is provided so as to correspond to each flow path 24 independently of each other, so that the piezoelectric element 22 is separated into a driving piezoelectric element 22a and a reinforcing piezoelectric element 22b. The ink droplets are ejected by driving the driving piezoelectric element 22a.

When the flow path 24 is sufficiently long, the pressure generated in the flow path (pressurized liquid chamber) 24 forms droplets and is repeatedly reflected and propagated to cause a standing wave of pressure inside the flow path. Is known to cause Therefore, the pressure inside the channel 24 repeats positive and negative vibrations, and the meniscus also vibrates following the positive and negative vibrations. Particularly, immediately after the formation of the droplet, the meniscus is largely drawn into the nozzle 30, and bubbles are likely to be entrained at that time. If air bubbles are present inside the flow path, the pressure may be absorbed and printing may not be possible. There are many measures for preventing air bubbles from being entrained from the nozzle 30, but the treatment of the surface of the nozzle 10 is roughly divided into the following two.

One is to prevent ink dripping by treating the nozzle plate surface with water repellency, as seen in JP-A-55-67473 and JP-A-55-161668.
It prevents the entrainment of air bubbles. The other is JP-A-58-90964 and JP-A-63-22285.
No. 9, JP-A No. 1-123752, etc., the surface of the nozzle plate is made of a hydrophilic material,
By forming an ink film on the surface, the ink is drawn in instead of the air bubbles, the air bubbles are prevented from being caught, and at the same time, the ink is rapidly supplied. As a result of the examination, it was concluded that making the surface of the nozzle plate hydrophilic makes it more advantageous for speeding up and high image quality of the inkjet printer.
The present invention provides an inkjet printer in which bubbles are less entrained than in the past by controlling the wet state of the surface.

[0006]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ink jet printer head of high image quality in which ink is stably supplied to a nozzle surface even when driving at high frequency and air bubbles are not entrained. It was made as.

[0007]

In order to achieve the above object, the present invention provides (1)
A nozzle plate having an orifice for ejecting ink, a pressurized liquid chamber communicating with the orifice for applying energy required for ink ejection, and an ink supply path for supplying ink to the pressurized liquid chamber In the inkjet printer head having an ink liquid film on the surface of the orifice, a barrier is provided on at least a part of the periphery of the orifice on the nozzle plate, or
(2) A nozzle plate having an orifice for ejecting ink, a pressurized liquid chamber which communicates with the orifice and applies energy required for ejecting ink, and an ink supply path for supplying ink to the pressurized liquid chamber In an inkjet printer head having an ink liquid film on the surface of the orifice, the surface of the nozzle plate has a distribution of liquid contact with the ink, and the area is hydrophilic near the orifice and is distant from the orifice. Shows water repellency, or (3) a nozzle plate having an orifice for ejecting ink, a pressurized liquid chamber which communicates with the orifice and applies energy required for ink ejection, and the pressurized liquid chamber. An ink jet printer having an ink liquid film on the surface of the orifice, which is composed of an ink supply path for supplying ink. In the head, the nozzle plate, across an orifice in the orifice array direction, by providing at least one groove, or, (4)
A nozzle plate having an orifice for ejecting ink, a pressurized liquid chamber communicating with the orifice for applying energy required for ink ejection, and an ink supply path for supplying ink to the pressurized liquid chamber In the ink jet printer head having an ink liquid film on the surface of the orifice, a groove having a diameter larger than the orifice diameter in the orifice arrangement direction is formed on the nozzle plate, and the orifice is arranged inside the groove. 5) In (4) above, the inside of the groove is subjected to a hydrophilic treatment and the outside of the groove is subjected to a water repellent treatment. Hereinafter, description will be given based on examples of the present invention.

FIG. 1 is a block diagram for explaining an embodiment of an ink jet printer head according to the present invention. In the figure, 1 is a substrate, 2 is a piezoelectric element, 3 is a flow channel plate, 4 is a flow channel (Pressure liquid chamber), 5 is a liquid sag prevention barrier, 6 is a nozzle plate, 7 is an orifice, and 8 is a protective plate. The inkjet head is viewed from the side of the nozzle plate, and droplets are discharged in a direction perpendicular to the direction of gravity.

In this case, the liquid film on the nozzle surface is easily pulled downward due to the effect of gravity, and as a result, the liquid film is likely to drip from the nozzle surface. If liquid drip occurs on the surface, if the timing is wrong, air bubbles are mixed from the nozzle, and printing cannot be performed. Further, since the ink drops on the lower part of the printer case, the inside of the case is easily soiled, which is problematic as a product. In order to prevent this, it is advisable to provide a barrier 5 for preventing liquid dripping below the nozzle plate 6. The height of the barrier cannot be generally stated because it is determined by the surface tension and viscosity of the ink, but for example, when the ink has a viscosity of 1.2 cp and a surface tension of 40.5 dyn / cm ² , a barrier of 100 μm is provided, Incline drastically decreased.

FIG. 2 is a view showing another embodiment of the nozzle plate of the ink jet printer head according to the present invention.
Instead of providing a barrier, the nozzle plate 6 is hydrophilically treated,
Alternatively, it is possible to prevent liquid dripping by using a hydrophilic material and subjecting only the lower portion of the nozzle plate 6 to water repellent treatment. FIG. 3 is a view of the nozzle plate 6 viewed from the droplet discharge direction, and the hatched portion in the drawing indicates the water repellent treatment portion 9.

3, 4 and 5 are views showing still another embodiment of the nozzle plate of the ink jet printer head according to the present invention. The present invention is effective even when the droplet discharge direction is not perpendicular to gravity. For example, by providing the barrier 5 in parallel with the nozzle arrangement direction, the ink is likely to collect around the orifice, the ink is prevented from flowing out to an extra area, and the ink can be concentrated near the orifice, which is efficient. The barrier does not have to be continuous as in FIG. 3, and the effect can be expected even if it exists only around the orifice as in FIG. In addition, as shown in FIG.
The same effect can be obtained by combining 0 and the water repellent treatment section 9. The barrier 5 in the present invention can be easily manufactured by a conventional inkjet processing technique, and may be ground or photo-edged. Further, as the member for obtaining hydrophilicity in the present invention, in the case of aqueous ink, for example, stainless steel, nickel, platinum, sapphire, ruby, glass, etc., hydrophilic treatment with epoxy resin, phenolic resin, cellulose acetate, etc. It may be one that has been subjected to. Examples of the water repellent agent include silicone type water repellents and fluorine type water repellents.

FIGS. 6 and 7 are views showing a structure for preventing entrainment of bubbles. As a method of preventing air bubble entrapment, the groove surface 11 may be formed on the orifice surface as shown in FIG. In this case, by forming the groove 11 so as to cross the orifice 7, ink is rapidly supplied from the connecting orifice 7 when the meniscus is pulled in, and air bubble entrapment is reduced. In addition, when the groove width is made larger than the orifice diameter and the orifice is completely inserted into the groove 11 as shown in FIG. At this time, if the inside of the groove 11 is made hydrophilic and the outside of the groove is made water-repellent, the ink easily accumulates inside the groove 11 and the air bubble entrapment is further reduced.

[0013]

[Effect] As is clear from the above description, according to the present invention, it is possible to realize a stable and reliable inkjet printer head with less bubble entrainment even at high frequency, high voltage, and multi-channel drive. it can.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of an inkjet printer head according to the present invention.

FIG. 2 is a view showing another embodiment of the nozzle plate according to the present invention.

FIG. 3 is a view showing still another embodiment of the nozzle plate according to the present invention.

FIG. 4 is a view showing still another embodiment of the nozzle plate according to the present invention.

FIG. 5 is a view showing still another embodiment of the nozzle plate according to the present invention.

FIG. 6 is a view showing still another embodiment of the nozzle plate according to the present invention.

FIG. 7 is a view showing still another embodiment of the nozzle plate according to the present invention.

FIG. 8 is a diagram showing a conventional inkjet printer head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Piezoelectric element, 3 ... Flow path plate, 4 ... Flow path (pressurized liquid chamber), 5 ... Liquid sag prevention barrier, 6 ... Nozzle plate,
7 ... Orifice, 8 ... Protective plate.

Claims (4)

[Claims] 1. A nozzle plate having an orifice for ejecting ink, a pressurized liquid chamber communicating with the orifice for applying energy required for ink ejection, and an ink for supplying ink to the pressurized liquid chamber. An ink jet printer head comprising a supply path and having an ink film on the surface of the orifice, wherein a barrier is provided on at least a part of the periphery of the orifice on the nozzle plate. 2. A nozzle plate having an orifice for ejecting ink, a pressurized liquid chamber which communicates with the orifice and applies energy required for ink ejection, and an ink for supplying ink to the pressurized liquid chamber. In an ink jet printer head having an ink liquid film on the surface of the orifice, the surface of the nozzle plate has a distribution of liquid contact with the ink, and is hydrophilic near the orifice and separated from the orifice. Ink jet printer head characterized by exhibiting water repellency in the region where 3. A nozzle plate having an orifice for ejecting ink, a pressurized liquid chamber communicating with the orifice for applying energy required for ink ejection, and an ink for supplying ink to the pressurized liquid chamber. In an inkjet printer head having an ink liquid film on the surface of the orifice, which is configured by a supply path, on the nozzle plate so as to cross the orifice in the orifice arrangement direction,
An inkjet printer head having at least one groove. 4. A nozzle plate having an orifice for ejecting ink, a pressurized liquid chamber which communicates with the orifice and applies energy required for ejecting ink, and an ink for supplying ink to the pressurized liquid chamber. An ink jet printer head having an ink liquid film on the surface of the orifice, the groove being larger than the orifice diameter in the orifice arrangement direction, and the orifices being arranged inside the groove. An inkjet printer head characterized by.