JPS60139454A - Ink jet head - Google Patents

Abstract

PURPOSE:To prevent the clogging of a nozzle orifice, by supplying a preserving solution to the nozzle orifice of an ink jet heat at the point of time when printing operation is stopped. CONSTITUTION:When an ink jet head 16 is driven in a container 17 and ink is injected from nozzle orifices 11A, 11B, 11C, 11D thereof, the state at the end surface of ink 19 in each of the nozzle orifices 11A, 11B, 11C, 11D is held under a state drawn into each of the nozzle orifices 11A, 11B, 11C, 11D from the end surface of each of them because the interior of each nozzle orifice is brought to negative pressure as compared with atmospheric pressure. Therefore, the driving of the ink jet head 16 is stopped in this state and a preserving solution 23 comprising an aqueous solution of ethylene glycol being the forming component of the ink is flowed into the container 17 from the preserving solution supply tube 20 provided to the upper part of said container 17 so as to reach the part of the receiving tray 22 provided to the lower part of the container 17 from the opening part 21 provided to the upper part of said container 17 along one flat surface 18 thereof. That is, the preserving solution 23 is dripped to the end surfaces of the nozzle orifices 11A, 11B, 11C, 11D and flowed into said nozzle orifices 11A, 11B, 11C, 11D.

Description

Detailed Description of the Invention: fat Technical Field of the Invention The present invention relates to an inkjet head, and more particularly to an inkjet head that prevents clogging of minute nozzle holes due to ink drying.

(bl Background of the technology) A voltage is applied to the piezoelectric element installed above the pressure chamber containing print recording ink to generate print information, and the pressure caused by this distortion is transmitted to the pressure chamber. However, an inkjet recording method is well known in which printing ink contained in a pressure chamber is ejected onto recording paper from a nozzle provided at one end of the pressure chamber in communication with the pressure chamber.This inkjet recording method is a non-impact recording method, which generates little noise during print recording and has a high print recording speed, so it has recently become widely used for recording output information from electronic computers.

(C1 Prior art and problems Figure 1 is a plan view of a conventional inkjet head, and Figure 2 is a plan view of a conventional inkjet head.
The figure is an i-plane view taken along line 1-IT of FIG. 1. As shown in the figure, a conventional inkjet head has a pressure chamber 2 that stores ink for printing and recording inside and communicates pressure from a piezoelectric element 1 with one end of this pressure chamber 2, and transfers the ink to a recording paper ( (not shown); an ink outlet path 4 communicating with the nozzle 3 from the pressure chamber 2; and an ink tank (not shown) for storing ink in order to supply ink to the pressure chamber 2. ) and an ink supply path 5 that supplies ink from this ink tank. Although not shown here, it is assumed that a large number of the piezoelectric elements 1, pressure chambers 2, nozzles 3, etc. shown in FIG.

By the way, a predetermined voltage is applied to the piezoelectric element 1 based on the information to be printed, the piezoelectric element 1 is distorted, the pressure of this distortion is transmitted to the pressure chamber 2, and ink is recorded from the nozzle 3 connected to the pressure chamber. If the printing operation of this inkjet head is stopped after a predetermined print is recorded by ejecting onto paper, that is, if the printer is left unused, the diameter of the nozzle 3 is very small, so the tip of the nozzle 3 In the part that is in contact with the atmosphere, solvents such as water and ethylene glycol in the ink forming material in the nozzle 3 evaporate, and dyes in the ink dry and remain in the nozzle hole, causing nozzle clogging. This caused the problem that the ink was not jetted onto the recording paper. Therefore, in order to solve this problem, the surface of the nozzle hole that comes into contact with the atmosphere is pressed with a rubber roller, or a container is provided to accommodate the surface of the nozzle hole that comes into contact with the atmosphere, and the inside of this container is Measures were taken to maintain high humidity.

However, in the former method, the equipment is complicated and large-scale, such as requiring a motor or coil to drive the rubber roller, and in the latter method, the nozzle surface is always Due to exposure to a humid atmosphere, the water repellency of the nozzle surface deteriorates, and small ink droplets adhere to the nozzle periphery, resulting in ink droplets not being formed properly and not being ejected onto the recording paper. Causes problems. In addition, with this method, if there is a large temperature difference between the inkjet head and the surrounding environment, condensation will form on the nozzle surface, making it difficult for the ink particles to be directed in the specified direction. There is a problem in that high-quality print recording cannot be achieved because the ink does not fly to the ground.

Therefore, as a result of various experiments, the inventors of the present invention found that on the nozzle surface where the nozzle hole is in contact with the atmosphere, the inside of the nozzle is under a negative pressure with respect to the atmosphere, and when ink is ejected from the nozzle to record By simply dropping an appropriate solvent onto the nozzle surface, this solvent can penetrate into the nozzle hole without impairing the water repellency of the nozzle surface, preventing the nozzle hole from clogging due to drying of the ink. I found it.

(d) Purpose of the Invention In view of the above-mentioned matters, the present invention eliminates the above-mentioned conventional problems, and uses a simple mechanism to prevent a solvent from dripping on the nozzle surface that comes into contact with the atmosphere, which can prevent ink from drying. in,
The object of the present invention is to provide a novel inkjet head in which this solvent is allowed to penetrate into the inside of the nozzle hole, thereby preventing clogging.

(e) Structure of the Invention In order to achieve the above object, the inkjet head of the present invention is an inkjet head for recording by ejecting ink particles from a nozzle hole, and when the printing operation of the inkjet head is stopped, The present invention is characterized in that a preservation liquid is supplied to the nozzle holes of the inkjet head to prevent the ink in the nozzles from solidifying.

Further, the storage liquid is formed from a solvent other than the dye among the ink forming materials.

Furthermore, the present invention is characterized in that the weight ratio of water in the storage liquid is smaller than the weight ratio of water in the ink.

(fl Embodiment of the Invention An embodiment of the invention will be described in detail below with reference to the drawings.

FIG. 3 is a perspective view showing the structure of the inkjet head of the present invention, FIGS. FIG. 7 is a relationship diagram showing the components of the storage liquid used in the inkjet head of the present invention and the state of clogging of the nozzle holes.

As shown in FIG. 3, there are four nozzle holes 11A and IIB.

11C, 110, and four piezoelectric elements 12A, 12! B
, 12C, 120 and four pressure chambers 138, 13B
, 13C, 130, and an ink supply pipe 15 connected to the ink storage chamber 14 through an ink tank (not shown). is housed in.

The nozzle holes 118, IIB, IIC, and 110 of the inkjet head 16 are installed inside the container I7 so that the end faces of the tips are flush with one plane 18 constituting the container 17. A container 101 having a rectangular parallelepiped shape and having no bottom surface has an opening 21 on the container 17 and is connected to a storage liquid supply pipe 20 that prevents the ink from drying.
is installed, and a saucer 22 is provided at the bottom of the container 17, projecting in a tapered shape from one plane 18 of the container 17. Inside such a container 17, the solo 6 is driven to the inkjet, and its nozzle holes 11A,
When ink is ejected from IIB, IIC, and LID, each nozzle hole 11A, IIB, and IIC as shown in FIG.
.

The state of the end surface of the ink 19 inside the LID is that the inside of the nozzle hole has a negative pressure compared to the atmosphere, so it is in a state of being retracted inward from the end surface of the nozzle hole 11A, IIB, IIC, and 110. . Therefore, in this state, the driving of the inkjet head 16 is stopped, and a preservation solution 23 made of an aqueous solution of ethylene glycol, which is a forming component of the ink, is poured from the upper part of the container 17 through the preservation solution supply pipe 20, and then One plane 18 of the container
The water is allowed to flow through the container 17 until it reaches the saucer 22 at the bottom of the container 17. That is, the nozzle hole as shown in FIG.
, IA, IIB, IIC, IID.
Let 3 drip down. Then, as shown by arrow A in FIG.
Since the inside of IC and IID has a negative pressure compared to the atmosphere,
The flow enters the inside of each nozzle hole 118, 11B, IIC, 110, and in this state, the nozzle hole 11A
.

11B, IIc, and 110 are no longer dried, and therefore the nozzle holes 11A
, IIB.

No clogging occurs inside the 11C, IID.

Next, when the inkjet head is driven to record prints on recording paper, as shown in FIG. 11A, IIB, 11G,
110 (7) Function: By pressurizing the ink in the ink tank, it is discharged into the tray 22 at the bottom of the container 17, and is discharged to the outside via the preservation liquid JJF outlet pipe 24.

Here, the present inventors used ethylene glycol, which is a forming component of the ink, diluted with water as a solvent as a storage solution to prevent clogging inside the nozzle hole. The ink used in this experiment contained 3% by weight of a dye (Kayascent Blank: trade name, Nippon Kayaku M) and Prepare and add 4 ethylene glycol as the remaining ink forming ingredients.
A mixture of 0% by weight and 60% by weight of water was used.

Using such a storage solution and ink, the state of clogging of the nozzle holes of the inkjet head was investigated by installing an inkjet printer equipped with the inkjet head in an environment with a relative humidity of 15% and a temperature of 25°C. , 7th
The results shown in the figure were obtained. In the figure, the vertical axis shows the elapsed time from when the inkjet head stopped driving until the nozzle hole became clogged with ink, and the horizontal axis shows the elapsed time from when the inkjet head stopped driving until the ink clogged. Weight percent of ethylene glycol is shown.

Note that the preservation solution was dripped onto the nozzle surface for several seconds. As shown in the figure, when the concentration of ethylene glycol becomes 40% by weight or more in a storage solution made of an aqueous solution of ethylene glycol, the time required for the nozzle hole to suddenly become clogged becomes longer. This is thought to be because as the concentration of ethylene glycol in the storage solution increases, the rate at which the ink in the nozzle holes 11A, IIB, 11C, and 11D diffuses into the storage solution becomes slower. Therefore, the percentage by weight of water in the storage solution made of a solution of water and ethylene glycol should be smaller than the percentage by weight of water in the solvent in the ink made of a dye and a solvent made of water and ethylene glycol. By doing so, the speed at which the ink diffuses into the storage liquid is reduced, and the effect of preventing ink clogging in the nozzle holes is further increased.

For comparison with the method of the present invention, when no storage liquid was used, clogging of the nozzle holes occurred 2 to 3 hours after ink was ejected.

(gl Effects of the Invention As described above, according to the inkjet head 1 of the present invention, since a preservation liquid is used, a simple device can prevent the ink inside the nozzle from drying without impairing the water repellency of the nozzle end face. This prevents clogging due to drying of the ink inside the nozzle.Also, since the ink flies in a fixed direction, a highly reliable inkjet head can be obtained.

[Brief explanation of the drawing]

Figure 1 is a plan view of a conventional inkjet printer I head;
The figure is a cross-sectional view of FIG. 1 taken along line I-n, FIG.
Figures 4, 5 and 6 are schematic diagrams showing the state of ink ejection at the nozzle hole of the inkjet head of the present invention, and Figure 7 shows the components of the storage solution used in the inkjet head of the present invention. FIG. 3 is a relationship diagram showing a state of clogging of a nozzle hole. In the figure, ■, 12^, 12B, 12G, 12
D is a piezoelectric element, 2.138, 13B, 13G, 1
30 is the pressure chamber, 3.118, IIB, IIG, 1
10 is a nozzle hole, 4 is an ink outlet path, 5 and 15 are ink supply pipes, 14 is a common ink chamber, 16 is an inkjet head, 17 and 101 are containers, 18 is a plane, 19 is ink, and 20 is a storage liquid supply pipe , 21 is an opening, 22 is a saucer,
23 is Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (3)

[Claims] (1) In an inkjet head that ejects ink particles from a nozzle hole for recording, when the printing operation of the inkjet head is stopped, the ink in the nozzle is prevented from solidifying in the nozzle hole of the inkjet head. An inkjet head characterized in that it is provided with a means for supplying a storage solution that prevents (2) The inkjet head according to claim (1), wherein the storage liquid is formed from a solvent other than the dye among the ink forming materials. (3) The inkgeno 1-head according to claim (2), wherein the weight ratio of water in the storage liquid is smaller than the weight ratio of water in the ink.