JPH08808U - Inkjet head - Google Patents

Abstract

(57) [Summary] Since the ink 14 does not adhere to the ink repellent region 42 provided around the pores 22, the next time the ink is ejected, the ink droplets may adhere to the ejection surface 38 due to the ink. Can be formed normally without inhibition,
The pores 22 resulting from the drying of the ink adhering to the firing surface 38
The clogging of is cleared.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to improvement of an inkjet head used in an inkjet printer.

[0002]

[Prior art]

 As one type of inkjet printer, there is a type in which an ink drop is intermittently ejected toward a printing surface by opening and closing a supply path of pressurized ink by an opening / closing control valve. For example, that described in US Pat. No. 4,378,564 (USP 4,378,564; MAR.29,1983) is that. Ink jet printers of this type have relatively large diameters of flying ink droplets but have a simple printer structure and are inexpensive, so they are used in the field of printing relatively large characters and symbols, such as on a conveyor. It is used when printing on the side of a corrugated cardboard box.

[0003]

[Issues to be solved by the device]

 By the way, an ink jet printer of the above type is usually equipped with an ink jet head which is connected to an ink supply path and has pores on the ejection surface for ejecting ink droplets toward the printing surface. However, when the ink supply path is blocked by the opening / closing control valve, the flying ink drops and the ink remaining on the firing surface due to the breakage close the pores, causing various inconveniences. In other words, if the pores are blocked by the ink that remains on the ejection surface and adheres, the ink droplets that should be ejected cannot be formed normally when ejecting the next ink, and the ejection direction and distance vary, which causes print quality. Is reduced. In addition, if the ink left on the firing surface is dried with the pores blocked, the pores become clogged and printing defects occur.

[0004]

[Means for solving problems]

 The present invention has been made in view of the above circumstances. The gist of the present invention is to intermittently inject ink drops toward the printing surface by opening and closing the supply path of the pressurized ink by the opening / closing control valve. In an ink jet printer of a type that causes the ink to fly, an ink jet head having a firing surface that is connected to the ink supply path and has pores for firing the ink droplets toward the print surface, The firing surface is provided with an ink repellent region surrounding the pores.

[0005]

[Effect of action and device]

 By doing so, since the ejection surface of the inkjet head is provided with the ink-repellent region surrounding the pores for ejecting the ink toward the printing target member, the opening / closing control valve can be closed. Even if ink remains on the firing surface of the inkjet head, the ink is repelled by the ink-repellent regions provided around the pores and excluded from the periphery of the pores. Therefore, at the next ink ejection, ink droplets can be formed normally without being hindered by the ink adhering to the ejection surface, and the pores are clogged due to the drying of the ink adhering to the ejection surface. Is eliminated.

Here, the ink-repellent area is an area having a large contact angle with respect to the ink, and the ink contacting the area becomes a bead shape due to the surface tension thereof and may be flown by gravity and remain around the pores. Can not. In the ink-repellent area, for example, when the portion where the pores of the ink jet head are formed is metal, a resin having ink-repellency such as a fluororesin or a silicone resin is coated on the surface around the pores as a layer. It is formed by Further, the portion of the inkjet head where the pores are formed may itself be formed of the resin having the ink repellency.

Further, the ink-repellent area does not necessarily have to be provided over the entire circumference of the pore, and even if it is provided around the pore and on the side where ink flows off, a temporary effect can be obtained. .

[0008]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, an ink jet printer is provided with an ink tank 12 connected to a compressed air passage 10, and a relatively high pressure transmitted through the compressed air passage 10 presses an aqueous or oil-based ink 14. It is supposed to be done. The ink 14 in the ink tank 12 is sequentially passed through the supply pipe 16, the plurality of electromagnetic on-off valves 18, and the plurality of supply pipes 20 to be supplied to an ink jet head 24 having a plurality of pores (nozzles) 22. ing. If necessary, the ink supply path may be one system or a plurality of two or more systems. In this embodiment, 12 systems are provided as described later.

The control circuit 26 opens and closes the electromagnetic opening / closing valve 18 in accordance with the movement of the cardboard box 30 on the roller conveyor 28, so that the ink is ejected from the inkjet head 24 toward the printing surface 31 of the cardboard box 30. Particles are fired to print desired characters or symbols on the surface 31 to be printed.

As shown in FIG. 2, the inkjet head 24 has a block-shaped main body 32 connected to twelve supply pipes 20 (only eight pipes are omitted in the drawing), and the main body 32. And a nozzle plate 36 fixed by screws 34 on the front surface of the. As shown in FIG. 3, the nozzle plate 36 is formed with twelve pores 22 arranged in a row in the vertical direction so as to penetrate therethrough, and these pores 22 are respectively formed in the main body 32. Each of the twelve supply pipes 20 is communicated with each other via the passage 40. The pores 22 are formed so as to be thinner on the side of the nozzle plate 36 on the firing surface. The nozzle plate 36 is made of metal such as stainless steel, and an ink-repellent region 42 continuous in the column direction of the pores 22 is provided at the peripheral edge of the pores 22 on the firing surface 38 thereof. The ink repellent region 42 is formed by locally coating a fluororesin layer with a thickness of about 5 to 10 μm, and the horizontal distance D between the outer peripheral edge thereof and the pore 38 is 0.5 to. It is set to 2 mm.

On the other hand, on the back surface of the nozzle plate 36, as shown in FIGS. 4 and 5, adhesive repellent regions 44 having a shape similar to that of the ink repellent regions 42 are arranged in the vertical direction at the peripheral edge of the pores 22. It is continuously provided in the direction. Further, as shown in FIG. 5, an adhesive repellent area 46 is also provided on a portion of the main body 32 which is combined with the nozzle plate 36 and faces the adhesive repellent area 44. The adhesive repellent area 44 and the adhesive repellent area 46 prevent the adhesive 48 applied between the main body 32 and the nozzle plate 36 from entering the pores 22 side during assembly in order to seal the space between the main body 32 and the nozzle plate 36. In this embodiment, it is formed by locally coating a silicone resin.

The operation and effect of this embodiment will be described below.

As shown in FIG. 1, since the ink is pressurized in the ink tank 12, the ink 14 is vigorously ejected through the pores 22 by opening the electromagnetic opening / closing valve 18. The ink 14 thus ejected becomes a plurality of ink drops due to the surface tension of the ink in the flight process, and sequentially arrives at the printing surface 31 of the cardboard box 30. FIG. 6 shows such a normal firing condition.

After that, when the electromagnetic opening / closing valve 18 is closed and the flow of the ink 14 is stopped, what has not yet become ink droplets at the outlet of the pore 22 is pulled back by the surface tension and flows down on the firing surface 38. At this time, the ink 14 flowing down on the firing surface 38 is repelled by the ink repellent region 42 provided around the pores 22 and does not adhere to the region 42. That is, since the contact angle between the ink 14 and the ink repellent area 42 is large, the ink 14 rolls into a ball shape. The ink 14 adheres to a place other than the ink repellent region 42, which is a metal surface, because the contact angle is small. FIG. 7 shows this state. In the figure, reference numeral 50 indicates a trace of the ink 14 flowing down, that is, a place where the ink 14 adheres.

As described above, in this embodiment, since the ink 14 does not adhere to the ink repellent area 42 provided around the pores 22, the ink droplets are ejected on the ejection surface 38 at the next ink ejection. In addition to being able to be formed normally without being hindered by the ink adhering to the ink, the clogging of the pores 22 due to the drying of the ink adhering to the firing surface 38 is eliminated.

Incidentally, when the ink repellent area 42 is not arranged around the pores 22, as shown in FIG. 8, some ink droplets are not yet formed at the outlet of the pores 22. It is pulled back by the surface tension and adheres to the firing surface 38. The ink 14 adhering to the vicinity of the pore 22 gathers with the ink subsequently ejected from the pore 22, so that normal ink droplet formation is hindered as shown in FIG.

Further, in this embodiment, since the ink-repellent area 42 is locally arranged around the pores 22, it is compared with the case where it is arranged on the entire firing surface of the nozzle plate 36. The advantage is that the ink 14 on the pores 22 is easily removed. That is, when the nozzle plate 36 is disposed on the entire firing surface, the ink on the pores 22 may become a ball shape and may be held by the surface tension of the ink in the pores 22, but When the permeable region 42 is locally arranged around the pores 22, the ink 14 on the pores 22 comes into contact with the outside of the ink repellent region 42 and the outside of the ink repellent region 42. Has a small contact angle, which has the advantage of flowing to that portion.

Next, another embodiment of the present invention will be described. In the following description, the same parts as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 10, an ink repellent silicon resin layer 52 may be provided on the inner peripheral surface of the pore 22. In this way, the ink 14 is less likely to adhere to the inner peripheral surface of the pore 22, which is advantageous in that clogging of the ink in the pore 22 is reduced.

Further, as shown in FIG. 11 or 12, when the intervals between the pores 22 are relatively large, annular ink-repellent regions 54 may be provided around the pores 22, respectively. Further, as shown in FIG. 13, the ink repellent region 42 may be divided between the pores 22 by slanting slits 56. By doing so, there is an advantage that the ink 14 left on the firing surface 38 is more surely removed from the pores 22.

Further, as shown in FIG. 14, the ink repellent area 42 can be provided around the pores 22 by forming the nozzle plate 36 with a fluororesin. In this case, it is desirable to provide the metal foil 58 at a position separated by 0.5 to 2 mm from the pore 22. By doing so, the contact angle with the metal foil 58 is smaller than that of the ink-repellent area 42, so that there is an advantage that the ink 14 on the pores 22 can be more suitably flowed.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other aspects.

For example, in the nozzle plate 36 of the above-described embodiment, the ink-repellent area 42 is made of a fluororesin coating, but it may be made of another resin layer such as silicon resin or an oil layer. Absent.

Further, the adhesive repellent area 44 and the adhesive repellent area 46 in the nozzle plate 36 and the main body 32 of the above-described embodiment are not necessarily provided.

Further, although the inkjet printer of the above-described embodiment is for printing the cardboard box 30, it can be applied to printing on packaging containers, building materials, agricultural products, and the like.

The above description is merely one embodiment of the present invention, and the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of an inkjet printer including an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of the inkjet head of FIG.

FIG. 3 is a perspective view showing a nozzle plate that constitutes the inkjet head of FIG.

FIG. 4 is a rear view of the nozzle plate of FIG.

5 is a horizontal cross-sectional view showing a main part of the inkjet head of FIG.

FIG. 6 is a diagram showing an ink ejection state of the embodiment of FIG.

FIG. 7 is a diagram showing a flow of ink on a firing surface after the ink has been fired.

FIG. 8 is a diagram corresponding to FIG. 7 in a conventional inkjet head.

FIG. 9 is a diagram corresponding to FIG. 6 in a conventional inkjet head.

FIG. 10 is a view corresponding to the main part of FIG. 2 in another embodiment of the present invention.

FIG. 11 is a view corresponding to the main part of FIG. 3 in another embodiment of the present invention.

FIG. 12 is a view corresponding to a main part of FIG. 3 in another embodiment of the present invention.

FIG. 13 is a view corresponding to a main part of FIG. 3 in another embodiment of the present invention.

FIG. 14 is a view corresponding to a main part of FIG. 2 in another embodiment of the present invention.

[Explanation of symbols]

 14: Ink 16, 20: Supply pipe (supply path) 18: Electromagnetic on-off valve (open / close control valve) 22: Pore 24: Inkjet head 31: Printed surface 38: Firing surface 42, 54: Ink repellent area

Claims (1)

[Scope of utility model registration request] 1. An ink jet printer of a type in which an ink drop is intermittently ejected toward a printing surface by opening and closing a pressurized ink supply passage by an opening / closing control valve, which is connected to the ink supply passage. An ink jet head having a firing surface with pores for firing the ink droplets toward the surface to be printed, wherein the firing surface has an ink-repellent region surrounding the pores. And inkjet head.