JPS62242546A - On-demand ink jet head and its manufacturing fittings - Google Patents

Abstract

PURPOSE:To eliminate a residual ink in an nozzle portion to enhance a printing quality, by a method wherein an edge of a nozzle of ink jetting side is composed of a ring-form recessed portion provided around a nozzle hole on the surface of a nozzle substrate and side faces of the nozzle hole. CONSTITUTION:A ring-form recessed portion 9a is provided around each nozzle hole, and a jetting-side edge of the nozzle hole is composed of the recessed portion 9a and side faces 9 of the nozzle hole. In this manner, in a coating treatment of a water repellent 10 on the jetting-side surface of the nozzle substrate provided with the ring-form recessed portion 9a around the nozzle hole, the water repellent 10 is led into the ring-form recessed portion 9a, thus being allowed to be coated approximately flush with the other surface while being sufficiently flush with the other surface while being sufficiently bonded onto the surface of the nozzle substrate to the edge portions of the nozzle hole. Therefore, adhesion of an ink around the nozzle on the nozzle substrate can be prevented, thus occurrence of satellite can be prevented to enhance a printing quality.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an on-demand ink jet head and a mold for manufacturing the on-demand ink jet head.

Flaming Rice 14 FIG. 3 is a cross-sectional configuration diagram for explaining an example of an on-demand inkjet head, and in the figure, 1 is a nozzle substrate;
2 is a vibration substrate, 3 is a diaphragm, 4 is an electrostrictive vibrator, 5 is a vibration transmission rod, and 6 is a diaphragm.

7 is an ink liquid chamber, 8 is an ink droplet, 9 is an inner surface of a nozzle hole, 1
0 is a water repellent treatment agent, and as is well known, the nozzle substrate 1 and the vibrating substrate 2 prevent ink filled in the ink chamber 7 for storing ink and the channel for supplying ink to the ink chamber 7 from leaking. The diaphragm 6 and the vibration transmission rod 5 are integrally provided on the vibration substrate 2 at a thin wall portion at a position corresponding to the nozzle position. A vibration plate 3 is connected to the tip of the vibration transmission rod 5, and an electrostrictive vibrator 4 is connected to the vibration plate 3, which is connected to the upper surface of the vibration substrate 2. The operation of the head is well known.

The applied voltage causes the electrostrictive vibrator 4 to deform downward,
By transmitting this force to the diaphragm 3 and pushing the diaphragm 6 downward from the vibration transmission rod 5, the ink filling the liquid chamber 7 is compressed, and the ink droplets 8 are ejected from the nozzle holes by this force. The inner surface of the nozzle hole 9 of the nozzle board 1 is treated with parent wood to make it more easily wetted by ink, in order to make it difficult to draw air into the nozzle when the diaphragm deforms upward and the pressure inside the ink chamber is reduced after ejection. Corona discharge treatment, Cr mixed solution, etc.) have been applied.

Further, a water repellent agent 10 is applied to the ink droplet ejection side so that the ink droplets do not adhere to the surface when the ink is ejected and are easily ejected in the form of particles. It is desirable that this water-repellent treatment extends to the edges of the nozzle holes as much as possible, but the treatment agent will not adhere to the vicinity of the edges.

In the conventional on-demand inkjet head as described above, the nozzle shape is configured such that the nozzle hole side surface 9 and the surface of the ejection side nozzle substrate 1 are perpendicular to each other, and the nozzle hole inner surface 9 has a shape that improves the wettability with ink. The nozzle substrate 1 is subjected to a hydrophilic treatment to prevent ink from adhering to it, and the jetting side surface of the nozzle substrate 1 is subjected to a water-repellent treatment to prevent ink from adhering to it. However, the adhesion of the water repellent agent to the corners around the nozzle hole is poor, and while ink is being jetted, there is a lot of residual ink in the nozzle corners, and the shape of the ink droplets when jetting becomes irregular or changes. As a result, satellites appeared and the quality of the seals deteriorated.

FIG. 4 is a diagram for explaining an example of manufacturing the nozzle substrate 1 in the on-demand inkjet head by plastic molding.
When forming a hole by plastic molding, as shown in FIG.
4, press the head of the core pin 11 and the surface of the core support 13 with mold clamping force,
It was molded by injecting resin and solidifying it. However, when the core pin 11 and the core support 13 are pressed together with mold clamping force to secure the shape and injection molded using such a press cutting method,
Core pin 11 may be damaged due to resin injection pressure or deformation during mold clamping.
A gap was created between the core support 13 and the resin, and the resin flowed into the gap, which formed a gap, making it difficult to secure the nozzle diameter and shape.

The present invention has been made in view of the above-mentioned circumstances.
The purpose of this invention is to provide an on-demand inkjet head that eliminates residual ink in the nozzle portion and improves printing quality, and a mold that can easily mold the on-demand inkjet head. .

In order to achieve the above object, the present invention provides that the edge of the injection side nozzle is constituted by a ring-shaped recess provided around the nozzle hole on the surface of the nozzle substrate and the side surface of the nozzle hole; In a mold for molding an on-demand inkjet head, a member softer than the core pin is tightly joined to one mold surface facing the core pin of mold 7, and the member is pressed against the core pin. It is characterized by being deformed into a mold for molding. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a sectional view of essential parts for explaining one embodiment of an on-demand inkjet head according to the present invention.
The same reference numerals as in FIG. 3 are given to parts that have the same function as the inkjet head shown in FIG. 3. Thus, in the present invention, a ring-shaped recess 9a is provided around each nozzle hole, and the recess 9a and the nozzle hole side surface 9 constitute the injection side edge of the nozzle hole. Furthermore, when coating the water repellent 10 on the injection side surface of the nozzle substrate having a ring-shaped recess formed around the nozzle hole in this manner, the water repellent 10 wraps around inside the ring-shaped recess 9a, causing other The water repellent 10 can be coated to a thickness that is almost flush with the surface, and the water repellent 10 can be sufficiently adhered to the edge of the nozzle hole. Note that the coating thickness of the commonly used water repellent agent is 10 .mu.m or less, and a ring-shaped recess having a depth of 3 to 7 .mu.m and a width of approximately 5 to 10 .mu.m provides a highly water-repellent effect.

FIG. 2 is a diagram for explaining an example of a mold for manufacturing the nozzle substrate 1 shown in FIG. The same reference numbers as in Figure 4 are provided. Therefore, in the mold according to the present invention, the core pin 11 is set higher than the PL surface of the mold (approximately 5 μm).
m) Fix it to the core block 12, and apply soft metal (Cu) to a thickness of about 10μ on one core support surface 13.
5, and finish the surface to be the same as the mold PL surface.

By clamping this mold, the core pin 11 is pressed against the plating layer 15 and bites into the plating layer 15 by the amount protruding from the PL surface, the plating layer 15 is pushed out to the periphery by the core pin 11, and the ring A raised convex portion 15a is formed. By injecting resin in this state, a ring-shaped recess can be formed in the hole and around the hole. In addition, since the core pin 11 is inserted into the plating layer of the core support 13 when forming the hole shape, even if the mold opens due to injection pressure, etc., it is possible to prevent the formation of burr in the hole part of the molded product. Can be done.

As is clear from the above description, according to the present invention, it is possible to prevent ink from adhering to the vicinity of the nozzle on the nozzle substrate, and it is possible to make the shape of ink droplets uniform. It is possible to provide an inkjet head that can improve print quality by preventing the occurrence of.

Further, it is possible to prevent the formation of cracks in the micro holes, and it is possible to easily process a mold that can form a ring-shaped recess around the micro holes.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram of main parts for explaining an example of an on-demand inkjet head according to the present invention, and FIG. 2 is a diagram for explaining an example of manufacturing a metal fitting for manufacturing the nozzle substrate shown in FIG. 1. illustration. FIG. 3 is a cross-sectional configuration diagram for explaining an example of a conventional on-demand inkjet head, and FIG. 4 is a diagram for explaining an example of manufacturing a mold for manufacturing the nozzle substrate shown in FIG. 3. It is. DESCRIPTION OF SYMBOLS 1... Nozzle board, 2... Vibration board, 3... Vibration plate, 4... Electrostrictive vibrator, 5... Vibration transmission rod, 6...
- Diaphragm, 7... Ink liquid chamber, 8... Ink droplet, 9... Nozzle hole inner surface, 9a... Recess, 10...
- Water repellent treatment agent, 11... Core pin, 12... Core block, 13... Core support, 14... Cavi block, 15... Plating layer, 15a... Convex portion. Patent applicant Ricoh Co., Ltd. Figure 1

Claims (3)

[Claims] (1) An on-demand inkjet head characterized in that the edge of the ejection side nozzle is constituted by a ring-shaped recess provided around the nozzle hole on the surface of the nozzle substrate and the side surface of the nozzle hole. (2) A water repellent agent having a high water repellency effect on ink is provided in the ring-shaped recess so as to be substantially flush with another surface of the nozzle substrate. The on-demand inkjet head according to item (1). (3) In a mold for forming an on-demand inkjet head, a member softer than the core pin is tightly joined to one mold surface facing the core pin of the mold, and the member is pressed against the core pin. 1. A mold for molding an on-demand inkjet head, characterized in that the mold is transformed by deforming the mold.