JPH0580752U - Inkjet printer head - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an inkjet printer head capable of clear printing without missing dots. A nozzle hole 5 has a cross-sectional shape that has a flat portion 5a and an inclined portion 5b whose diameter gradually increases toward the ink ejection side. [Effect] By having the inclined portion whose diameter gradually increases, ink is collected in the inclined portion, the nozzle hole is completely blocked, and the meniscus is not drawn into the ink pressure chamber. For this reason, stable ink ejection can be performed without generating bubbles.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an inkjet printer head, and more particularly, to a shape of a nozzle hole of a nozzle plate of the head.

[0002]

[Prior Art]

 Inkjet printers, which are non-impact printers, have a simple head structure and excellent color compatibility. For example, Japanese Unexamined Patent Publication No. 63-25270 discloses a head for an ink jet printer which prints by ejecting a fixed amount of ink from a nozzle hole by using deformation of a piezoelectric element in a shear mode. The main part of this head has a structure as shown in FIG. Ink supplied from an ink tank (not shown) enters the ink supply path 12 from the ink supply port 11, the ink is supplied to a large number of ink pressure chambers 13, and the mechanical displacement of the piezoelectric element 14 causes the ink pressure chamber 1 The pressure of No. 3 rises, and ink is ejected from the nozzle holes 16 formed in the nozzle plate 15 for printing. Here, in order to stabilize the print quality, it is important to stably eject a certain amount of ink to a predetermined position, but the processed shape of the nozzle hole greatly affects the print quality.

[0003]

[Problems to be solved by the device]

 However, according to the above-mentioned conventional example, as shown in FIG. 5A, the nozzle hole 25 opened in the nozzle plate 15 has a straight sectional shape. The ink 26 becomes particles 26a as shown in FIG. 5B, and is separated into droplets 26b as shown in FIG. 5C, and the meniscus 28 is drawn into the ink pressure chamber 29 in the nozzle. Get caught. When the meniscus 28 is drawn into the ink pressure chamber 29 in the nozzle as shown in FIG. 5D, the meniscus 28 exceeds the inner end 25a of the nozzle hole 25 when the drawing speed exceeds a certain limit. There is a problem that the narrowed portion 28a is generated and remains as a bubble in the ink 26 in the ink pressure chamber 29, and the bubble makes the particle formation unstable during the next ink ejection. This problem is particularly remarkable in an inkjet printer head using an electromechanical conversion element such as PZT, but it is a problem common to other types of inkjet printers such as a bubble jet.

An object of the present invention is to provide an ink jet printer which prevents meniscus from being drawn into the ink pressure chamber of the above head, realizes stable ink ejection, and enables clear printing without missing dots. To do.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention has a nozzle hole for ejecting ink, which is provided on a nozzle plate of an ink jet printer head, as a portion having a constant hole diameter from the ink pressure chamber side toward the ink ejection side. It is characterized by having a part where the hole diameter is increased to the discharge port.

[0006]

[Action]

 As in the present invention, by making the cross-sectional shape of the nozzle hole into a trumpet shape on the outside of the ink ejection port, the ink is collected in the trumpet-shaped part so as to close the hole, and the meniscus is prevented from being drawn into the ink pressure chamber, and The formation of droplets is stably performed from the formation. Further, by leaving the flat portion, the ejection direction is determined while the ink passes through the flat portion, and the accuracy of the ink ejection position, that is, the ink landing position becomes stable.

[0007]

【Example】

 An embodiment of a nozzle plate of an inkjet printer head according to the present invention will be described below with reference to the drawings. 1 and 2 are sectional views of a nozzle hole portion of the present invention. In FIG. 1, a nozzle plate 10 is joined to an ink pressure chamber 9 composed of a piezoelectric element 3 filled with ink. The cross-sectional shape of the nozzle hole 5 of the nozzle plate 10 forms a flat portion 5a having a length of 0.030 mm toward the ink ejection port side 2 and an inclined portion 5b having a gradually increasing diameter at θ of 45 °. When the ink ejection force is significantly improved, the appropriate value can be adjusted by the length of the flat portion and the angle of the inclined portion.

FIG. 2 shows another embodiment of the present invention in which the central portion of the nozzle hole 5 has a flat portion 5a at the same angle as that of the example of FIG. In this example, the inclined portions 5b and 5c whose diameter gradually increases are formed. By providing the inclined portion 5c, the pressure of the ink pressure chamber 9 rises due to the mechanical displacement of the piezoelectric element, and when the ink 6 becomes the particles 6a, the ink flow is concentrated in the nozzle hole 5 along the inclined portion 5c. Flow is improved and the stability of ejection is improved.

FIG. 3 shows a state in which ink is ejected from the nozzle hole portion of the present invention. FIG. 3A shows a state in which the ink 6 in the ink pressure chamber 9 is discharged from the nozzle hole 5 having the inclined portion 5b to be turned into particles 6a. The particles 6a then become droplets 6b as shown in FIG. 3 (b). At this time, the meniscus 8 is generated. Conventionally, the meniscus was previously drawn from the nozzle hole 5 to the ink pressure chamber 9, but as shown in FIG. 3 (b), the ink accumulated in the sloped portion 5b on the ink discharge side of the nozzle according to the present invention causes the ink pressure chamber to move. It is blocked without being pulled up to 9. FIGS. 3 (c) and 3 (d) show a state in which the ink 6 is accumulated on the outer slope 5b of the present invention when the head is stationary. 3C shows the case where the nozzle hole 5 has only the outer inclined portion 5b, and FIG. 3D shows the case where the nozzle hole 5 has the inner inclined portion 5c in addition to the outer inclined portion 5b. In any configuration, the meniscus is not drawn into the ink pressure chamber 9 as in the conventional example shown in FIG. Therefore, the next droplet can also be smoothly discharged from the nozzle hole 5.

[0010]

[Effect of the device]

 As described above, since the nozzle hole provided in the nozzle plate of the inkjet printer head according to the present invention has a trumpet shape in cross section, ink collects on the outer side of the nozzle hole and the meniscus causes ink pressure. The ink will not be drawn into the room to form bubbles, and stable ink ejection will be possible, resulting in a highly reliable ink jet printer head.

[Brief description of drawings]

FIG. 1 is a sectional view of a hole portion of an outer trumpet-shaped nozzle plate showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a hole portion of a nozzle plate having a trumpet shape on both sides showing another embodiment of the present invention.

FIG. 3 is a view showing a cross section of a nozzle hole portion of the present invention and an ink ejection state.

FIG. 4 is a structural diagram of an inkjet head.

FIG. 5 is a diagram showing a cross section of a conventional nozzle hole portion and an ink ejection state.

[Explanation of symbols]

 2 Ink ejection side 3 Piezoelectric element 5 Nozzle hole 5a Nozzle hole flat part 5b Nozzle hole outside inclined part 5c Nozzle hole inside inclined part 6 Ink 9 Ink pressure chamber 10 Nozzle plate

Claims (2)

[Scope of utility model registration request] 1. A nozzle hole for ejecting ink, which is provided in a nozzle plate of an inkjet printer head, has a constant hole diameter from the ink pressure chamber toward the ink ejection side, and a hole diameter from the ink pressure chamber to the ejection port. And an increased portion of the inkjet printer head. 2. The ink jet printer head according to claim 1, wherein the nozzle hole has a portion in which the hole diameter increases from a portion having a constant hole diameter toward the ink pressure chamber side.