JPH0380110B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet device equipped with an inkjet nozzle recovery device, and more particularly to an inkjet device equipped with a non-contact inkjet nozzle recovery device that prevents ink from being ejected.

If an inkjet nozzle is not used for a long period of time, the ink at the tip of the nozzle may dry, dust may adhere, and furthermore, ink may leak during transportation or storage. To prevent this, the tip of the nozzle is usually sealed with a cap. There are two types of capping devices for the nozzle tip: a type that directly contacts the nozzle and a non-contact type. With the contact type, if paper scraps, foreign matter, etc. adhere to the cap, the dust may be transferred and, in the worst case, the nozzle tip may be damaged. In the non-contact type, an air layer is formed between the tip of the nozzle and the cap, so changes in temperature and pressure cause the air to expand and compress, causing movement of the ink level within the nozzle. However, this movement of the liquid level is not necessarily reversible, and therefore,
An air layer may be formed within the nozzle, resulting in ink failure to be ejected. FIG. 1 shows the state of the nozzle tip. Normally, as shown in FIG. Ink I is ejected from the ejection port. A concave meniscus M is formed at the tip of the nozzle N due to the surface tension of the ink. However, this meniscus M is affected by a change in the air pressure at the nozzle tip of only about 0.05 atm.
Air easily enters the nozzle N. This air pressure fluctuation is caused by thermal expansion of the air, changes in air pressure, etc., and is also caused by the removal and removal of the cap. The state in which air has entered is shown in FIG. 1b, and this occurs because the meniscus does not return reversibly even if the atmospheric pressure changes reversibly.The main reason for this is as follows.
In other words, the liquid wetting is not uniform on the inner wall of the nozzle N, and as a result, a liquid film L is formed before the air inside the nozzle escapes from its tip, and eventually air a enters the nozzle as shown in Figure 1b. . In this state, if the piezoelectric element E is displaced for a minute time of only a few tens of microseconds, energy is consumed for instantaneous air compression, and no ink is ejected. Therefore, even if the cap is removed, printing cannot be started immediately.
I had to do a test print.

The present invention has been made in view of the above points, and when the cap that is capped at the tip of the inkjet nozzle is removed, a negative pressure is generated in the space formed between the cap and the inkjet nozzle. An object of the present invention is to provide an inkjet device equipped with an inkjet nozzle recovery device that sucks out and removes air, dust, etc., and thereby enables the inkjet nozzle to eject immediately after the cap is removed.

The present invention, which achieves these objects, comprises: a cap capable of being in a capped state covering an ejection port for ejecting ink and in a non-capping state separated from the ejection port; and when the cap is in the capping state. a suction means for performing a suction operation from the discharge port through the cap; a communication path for communicating the inside of the cap with the atmosphere; An inkjet device comprising: a valve that opens when the pressure is positive and closes when the pressure is negative.

The present invention will be described in detail below based on drawings of embodiments. FIG. 2 shows an inkjet device including an inkjet nozzle recovery device according to an embodiment of the present invention. 1 is the stand of this device;
A guide shaft 2 is supported and fixed on both ends thereof. A part of the guide shaft 2 is inserted through the shaft,
An axially slidable cylindrical holder 3 is supported. A coil spring 4 is inserted into the guide shaft 2 so as to separate the base 1 and the holder 3. 5 is a cylindrical cap fixed to the cylindrical inner wall of the holder 3 and has elasticity. The cap 5 forms a cylinder, and a piston 6 constituting a suction means having a hemispherical bulge at the other end is fitted into the cap 5. Further, a spring 7 is provided between the holder 3 and the hemispherical portion of the piston 6 so that the two are separated. Reference numeral 8 denotes a lever for moving the cap 5 and the piston 6, which moves at right angles to the moving direction of the piston 6 and the holder 3, and places the hypotenuse surface 8a of the lever 8 on the hypotenuse surface 1a of the table 1. When lever 8 is pushed down, holder 3 is pushed out in direction A. Furthermore, in lever 8,
The piston 6 is provided with a cam surface 8b that comes into contact with a hemispherical portion of the piston 6 to form a cam,
Similarly, the piston 6 is pushed out in the A direction by pressing down the lever 8. 8c and 8d are projections for regulating the amount of vertical movement of the lever 8, and are locked to a stopper 1b formed integrally with the base 1. Further, as shown in FIG. 3, the lower end of the lever 8 is provided with a protruding portion 8e that is engaged with a claw portion 1c that is integrally provided on the base 1 and holds the lever 8 at the lowermost position. Reference numeral 9 denotes a nozzle, and a nozzle pipe 9a is supported inside the nozzle by being wrapped around a piezoelectric element 10, and its tip has a flat surface so as to come into close contact with the cap 5.

FIG. 4 shows the state in which the lever 8 is pressed down, and FIG. 6 shows an overview thereof.

FIG. 5 shows a cross-sectional view taken along the line -- in FIG.
Further, the sucked ink is discharged from the discharge nozzle 13 to the outside. This pressure regulating valve 1
2 opens the outlet opening when the piston 6 moves in the A direction, and closes it when it moves in the opposite direction.

Next, the operation will be explained with reference to the timing chart of FIG. When attaching the cap to the nozzle, press down the lever 8 and press the cam surface 8b of the lever 8.
presses the hemispherical portion of the piston 6. At this time spring 7
By making the elastic force of the spring stronger than that of the spring 4, and without changing the relative position of the piston 6 and the holder 3, the holder 3 is moved in the direction A in FIG.
Extrude to. As the holder 3 moves by a predetermined amount, the cap 5 made of an elastic body comes into contact with the tip of the nozzle 9.
The compression restricts the movement of the tip of the cap 5 (b). Immediately before the tip of the cap 5 stops moving, the piston 6 starts sliding within the cap 5 (c). In the above, the piston 6 always opens the discharge hole 11, which serves as a communication path for communicating the inside of the cap with the atmosphere, and the space inside the cap opens when the inside of the cap is under positive pressure relative to the atmospheric pressure. The pressure is always maintained at a constant pressure by the pressure regulating valve 12, which closes when . Immediately before the lowest position of the lever 8, the piston 6 closes the discharge hole 11 for the first time. The most desirable thing is for the piston 6 to stop moving at this point and be fixed to the table 1 by the claw part 1c, but in this embodiment, it is assumed that the piston 6 is still moving, and the tip of the nozzle is fixed as shown in (d). Pressure increases slightly.

Next time you remove the cap, pull up the lever 8. When removing the lever 8, the protruding portion 8e of the lever 8 is removed from the claw portion 1c of the base 1, and the springs 4 and 7 cause the opposite operation to the above-described mounting operation. At this time, as the piston retreats, a negative pressure is generated in the cap space, and the air inside the nozzle is sucked and discharged from the nozzle along with the ink. As described above, according to this embodiment, the cap can be attached and attached by a simple operation of pushing down or pulling up the lever.
The air in the nozzle can be removed and the air inside the nozzle can be suctioned and discharged, resulting in very good operability.

It should be noted that the present invention is not limited to the above embodiment, and if the air pressure regulating valve ideally has diode characteristics, it is not necessary for the piston to close the discharge port of the cap.

As described above, according to the present invention, it is possible to cap the tip of an inkjet nozzle to prevent drying of the nozzle tip, adhesion of dust, and ink leakage.
When the cap is removed, a negative pressure is generated at the tip of the nozzle to suck air, dirt, etc. inside the nozzle, and the nozzle can be made to discharge normally immediately after the cap is removed.

That is, according to the present invention, recovery from ink ejection failure can be reliably performed by using the suction means.

Furthermore, according to the present invention, the communication path for communicating the inside of the cap with the atmosphere is provided with a valve that opens when the inside of the cap is under positive pressure relative to the atmospheric pressure and closes when under negative pressure. In addition to pressure changes within the cap that occur when the cap transitions from the capping state to the capping state (generation of positive pressure), it also covers pressure changes that may occur within the cap due to malfunction of the suction means, etc. , can be absorbed, buffered and compensated. What is this unlikely malfunction?
For example, this refers to a case where, when the cap is in the capping state, the suction means operates in the opposite direction during the suction operation and performs a pressurizing operation on the discharge port that is opposite to the suction operation.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the tip of the inkjet nozzle.
FIG. 2 is a sectional view of an embodiment of the present invention. FIG. 3 is a sectional view of the locking mechanism of the above embodiment. FIG. 4 is a sectional view when capping is performed in FIG. 2. FIG. 5 is a sectional view taken along the line -- in FIG. 4. FIG. 6 is a general front view of FIG. 4. Figure 7 is a timing chart. Here, 3 is a holder, 5 is a cap, 6 is a piston, 8 is a lever, and 9 is a nozzle.

Claims (1)

[Scope of Claims] 1. A cap capable of taking a capping state in which it covers an ejection port for ejecting ink and a non-capping state in which it is separated from the ejection port; a suction means for performing a suction operation from the discharge port through the cap; a communication path for communicating the inside of the cap with the atmosphere; and a communication path provided in the communication path to maintain a positive pressure inside the cap relative to the pressure of the atmosphere. An inkjet device comprising: a valve that opens when there is a negative pressure and closes when there is a negative pressure.