JPH09314858A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an economical effect by significantly minimizing an ink amount discarded for disposal in discharging a bubble. SOLUTION: This ink jet printer consists of a main tank 1 for storing ink and manifolds 5a-5d for supplying the ink to a nozzle 4 and recovering a purging ink on the main tank 1 side. In addition, the manifold 5c positioned at a point downstream from the nozzle 4 is arranged in such a manner that the manifold 5c is set at an angle of elevation θ halfway based on the main tank 1 as reference. Further, a valvular means is provided near the highest position of the manifold 5c so that a bubble is discharged to the outside of the printer and the purging ink is recovered on the main tank 1 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer, and more particularly, to a bubble purging mechanism for an inkjet printer.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view of a print head of a conventional ink jet printer.

In the figure, an electromechanical conversion element (hereinafter referred to as PZ
Displacement 54 (referred to as T) acts on the ink in the chamber 52 via the diaphragm 53, and ink particles are ejected from the nozzle port 51.

At this time, if air bubbles are mixed in the ink in the chamber 52, there is a problem that ink particles do not fly out.

Therefore, no bubbles should exist in the ink in the manifold 55 of the ink supply path as well as in the chamber 52.

In consideration of this point, conventionally, a method called pressure purging for discharging bubbles in the ink from the nozzle 51 has been adopted.

By the way, in the case of the pressure purging, it takes a very long time to discharge the bubbles in the ink only from the nozzle 51, and the pressing force is limited. In particular, in the case of a so-called multi-nozzle type inkjet having a plurality of nozzles, it is difficult to remove bubbles only by discharging from the nozzle 51, and it is necessary to apply a higher pressure for a long time.

In order to solve this problem, a check valve composed of a ball 57 and a spring 58 is installed as shown in FIG.

That is, by installing a check valve, when a high pressure is applied, the check valve operates and ink containing air bubbles is discharged from the ejection port 59, and when a low pressure is applied. The check valve does not operate and air bubbles are discharged only from the nozzle 51. This will be described in the case of actually discharging bubbles. First, a high pressure is applied in a state where the bubbles are collectively stored in the chamber 52, the check valve is opened, and most of the bubbles are discharged from the discharge port 59. Then, the bubbles remaining in the nozzle 51 are discharged from the nozzle 51 at a low pressure.

Various measures have been taken in order to reduce the amount of ink that goes out, that is, the amount of waste ink, by devising the amount of pressurization, the length of pressurization time, the number of pressurizations, and the like.

[0011]

However, even in the above-mentioned conventional bubble purging mechanism, all the ink for discharging bubbles is still discharged outside the printer, and the ink that has been discharged outside the printer is discarded.

That is, there has been a problem that all the ink originally used for printing is discarded because air bubbles generated in the ink flow path are discharged.

It is an object of the present invention to provide an ink jet printer which has an economical effect by minimizing the amount of ink that is discarded for discharging bubbles.

[0014]

The object is to dispose a main tank for storing ink and a manifold for supplying ink to the nozzle and collecting purge ink to the main tank side. Based on the above, the manifold located downstream of the nozzle is arranged so as to have an elevation angle in the middle, and near the highest position of the manifold, bubbles are discharged to the outside of the machine and the purge ink is collected on the main tank side. This is achieved by providing valve means for

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described based on an embodiment of the drawings.

FIG. 1 is a perspective view of a print head of an ink jet printer according to the present invention.

In the figure, the main tank 1 is capable of supplying ink to the nozzle 4 via the manifold 5 (5a, 5b). 3 is an orifice.

The main tank 1 also includes a manifold 5
It communicates with the sub tank 2 via c and 5d, and the manifold 5c is arranged at an elevation angle θ.

One side of the ink discharge path 10 is the manifold 5.
It is connected to the top of c and the other is opened to the upper part of the sub tank 2.

Reference numerals 15 and 16 are ink amount sensors provided in the main tank 1 and the sub tank 2, respectively.

FIG. 2 is a sectional view of the ink discharge path 10 and related portions.

A check valve composed of a ball 13 and a spring 14 is arranged in the ink discharge path 10 in the vicinity of the manifold 5c.

Further, the manifold 5d has a cross-sectional area smaller than a part or all of the other manifolds 5a, 5b and 5c.

An upper surface 11 of the sub tank 2 is an air hole.

Next, the operation will be described.

A pressure pump (not shown) for the main tank 1
When the low pressure is applied by, the ink in the main tank 1 passes through the manifolds 5a and 5b, and is discharged from the nozzle 4 through the orifice 3 to the outside. In addition, the ink is collected in the sub tank 2 through the manifolds 5c and 5d. At this time, the air bubbles in the nozzle 4 are discharged together with the ink discharged from the orifice 3, and the air bubbles in the manifold 5 are stored in the upper portion of the manifold 5c.

Next, when the main tank 1 is pressurized to a high pressure, the ball 13 in the check valve provided inside the ink discharge path 10 moves, and the air bubbles accumulated in the manifold 5c are discharged to the ink discharge path 10 together with the ink. discharge. At this time, in order to increase the purging efficiency, as compared with the amount of ink flowing from the manifold 5c into the sub tank 2 via the manifold 5d, the ink discharge passage 10 from the manifold 5c is compared.
It is advisable to increase the amount of ink discharged to. Here, since the discharged ink is not discarded to the outside, one end of the ink discharge path 10 is opened to the upper part of the sub tank 2.

In order to return the ink collected in the sub tank 2 by purging to the main tank 1, it is sufficient to pressurize the inside of the sub tank 2 with a pressure pump (not shown).

[0029]

As described above, according to the present invention, the main tank for storing the ink and the manifold for supplying the ink to the nozzle and collecting the purge ink to the main tank side are arranged, and the main tank is used as a reference. The manifold located downstream of the nozzle is arranged so as to have an elevation angle in the middle, and near the highest position of the manifold, air bubbles are discharged to the outside of the machine and the purge ink is collected on the main tank side. According to the present invention, which is provided with valve means,
It is possible to minimize the amount of ink that is discarded because air bubbles are discharged, and to improve the economic effect of using the inkjet printer more than before.

[Brief description of drawings]

FIG. 1 is a perspective view of a printhead of an inkjet printer according to the present invention.

FIG. 2 is a cross-sectional view of an ink discharge path indicated by reference numeral 10 in FIG. 1 and a related portion.

FIG. 3 is a cross-sectional view of a printhead of a conventional inkjet printer.

[Explanation of symbols]

1 ... Main tank, 2 ... Sub tank, 3 ... Orifice,
4 ... Nozzle, 5 (5a, 5b, 5c, 5d) ... Manifold, 10 ... Ink discharge path, 13 ... Ball, 14 ... Spring.

Claims (2)

[Claims] 1. An ink jet printer for ejecting ink from a nozzle to print, an ink having a main tank for storing ink, and a manifold for supplying ink to the nozzle and collecting purge ink to the main tank side. A circulation system is provided, and in the ink circulation system with respect to the main tank, the manifold located downstream of the nozzle is arranged so as to have an elevation angle halfway up to the main tank, and is located near the highest position of the manifold. An ink jet printer characterized in that valve means for discharging bubbles to the outside of the machine and collecting the purge ink on the main tank side is attached. 2. A main tank for storing ink, a sub-tank for collecting purge ink to the main tank side, and a manifold for connecting the sub-tank and the main tank and supplying ink to the nozzle. The manifold extending from the nozzle to the sub-tank is arranged so as to have an elevation angle up to the middle of the main tank. Bubbles are discharged to the outside of the machine and the purge ink is stored in the sub-tank near the highest position of the manifold. Inkjet printer equipped with valve means for