JP3108970B2 - Ink jet device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The present invention relates to an ink jet recording apparatus for forming an ink image on a recording medium such as recording paper at a high speed.

[0002]

2. Description of the Related Art A nozzle for discharging ink, a pressure chamber communicating with the nozzle, a pressure generating element for generating pressure in the pressure chamber, and voltage applying means for applying a voltage to the pressure generating element are provided. An ink jet apparatus that generates pressure in accordance with a change in applied voltage, discharges ink droplets, and prints on a recording medium is disclosed in, for example,
No. 65559. In such an ink jet apparatus, a method of providing a valve in an ink supply path in order to increase the ejection speed of ink droplets, to smoothly supply ink, and to prevent air bubbles from flowing from a nozzle is known. JP-A-62-160243
And Japanese Patent Application Laid-Open No. 2-270561.

[0003]

SUMMARY OF THE INVENTION The aforementioned Japanese Patent Application Laid-Open No. Sho 62-1
The ink jet device described in Japanese Patent No. 60243 has a problem that, due to its structure, it is difficult to manufacture a valve itself having good characteristics and small variations.

[0004] The ink jet apparatus described in Japanese Patent Application Laid-Open No. 2-270561 requires a piezo dedicated to a valve and a dedicated circuit for driving the piezo, so that the apparatus becomes expensive and complicated. Have.

[0005]

An ink jet apparatus according to the present invention includes a pressure chamber and an ink supply path for supplying ink to the pressure chamber. The ink supply path and the pressure chamber communicate with the wall surface of the ink supply path. An elastic body is disposed so as to maintain the state and vary the flow path resistance of the ink supply path according to the pressure in the pressure chamber. Further, the ink jet apparatus of the present invention includes a pressure chamber, and an ink supply path for supplying ink to the pressure chamber, and a part of a structural material that divides the supply path and the pressure chamber includes a pressure chamber according to the pressure in the pressure chamber. An elastic body that increases or decreases the flow path resistance of the supply path is arranged,
At least a part of the periphery of the elastic body is not supported by the structural material. Further, in the ink jet apparatus, when the pressure generation in the pressure chamber is in a standby state, the elastic body does not increase the flow path resistance of the supply path.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view for explaining a first embodiment of the ink jet apparatus of the present invention. The nozzle 1 and the pressure chamber 2 are in communication. The pressure generating element 3 is joined at a position facing the nozzle 1 of the pressure chamber 2. A voltage applying means (not shown) is connected to the pressure generating element 3.
The ink is supplied via a supply path A, and the pressure chamber 2 is filled with the ink. When a voltage signal is applied to the pressure generating element 3, the pressure generating element 3 expands and contracts, the movable wall 4 is moved, and the ink pressure in the pressure chamber 2 changes. Drops are selectively ejected.

Next, attention is paid to the supply route A. FIG. 2 is a perspective view showing the structure of this part. FIG. 3 is an exploded view of an elastic body 5 and structural materials 7, 8, and 9 to be joined respectively. The elastic body 5 forms a part of the wall of the supply path A. Further, the elastic body 5 is bonded to the structural material 7, but since the structural material 7 has the opening 6, the elastic body 5 has a free portion 100 which is not bonded to the structural material 7 surrounded by the peripheral portion 101. Free Club 1
00 also forms a part of the wall of the pressure chamber 2.

Both surfaces of the free portion 100 of the elastic member 5 are in contact with the ink in the pressure chamber 2 and the ink in the supply path A, respectively.

The pressure at the point y changes according to the expansion and contraction of the pressure generating element 3. On the other hand, since the ink pressure in the ink tank (not shown) is constant, the ink pressure in the x portion of the supply path A close to the ink tank is substantially equal to the ink pressure in the ink tank, and is considered to be constant. Therefore, the elastic body 5
The free portion 100 elastically deforms according to the ink pressure of the y portion, the surface area increases, and the free portion 100 expands in the direction of arrow B or arrow C.

The trapezoid signal is generally used as a drive signal for the pressure generating element 3. The relationship between the drive signal and the movement of the elastic body 5 and the function thereof will be described using the trapezoidal signal as an example.

FIG. 3 shows trapezoidal signals used in the embodiment as drive signals. In the figure, the component 11 of this signal,
Reference numerals 12 and 13 denote a rising portion, a holding portion, and a falling portion, respectively. When the rising voltage signal is applied, there are an ink jet device in which the pressure in the pressure chamber 2 rises and an ink jet device in which the pressure drops, but in the present embodiment, the former is adopted. In the latter case as well, the ink jet device of the present invention can be similarly configured.

When the rising portion 11 is applied to the pressure generating element 3, the pressure generating element 3 extends in the vertical direction (FIG. 1), the volume of the pressure chamber 2 is reduced, and the average pressure therein increases. The peak value is 5 atm. The pressure at the point y substantially coincides with the average value, and reaches a peak of 5 atm. As the pressure in the pressure chamber 2 rises, the ink droplet starts to protrude from the nozzle 1. The ink ejection continues until just before the application of the hold unit 12 is completed. At the same time as the ink is projected from the nozzle 1, a part of the ink follows the supply path A in the reverse direction and flows back to the ink tank. Further, as described above, the ink pressure in the x portion of the supply path A is substantially constant, and is about 1 atm.
The elastic body 5 expands in the direction of arrow B as the ink pressure in the opening 6 communicating with the pressure chamber 2 or the ink pressure in the y-section increases. As a result, the supply path A becomes narrower, the flow path resistance increases, the backflow of ink to the ink tank is prevented, and a large amount of ink is ejected from the nozzles 1.

On the other hand, the falling portion 13 is connected to the pressure generating element 3.
Is applied, the pressure generating element 3 moves in the vertical direction (FIG. 1).
), The volume of the pressure chamber 2 is increased, and the average pressure therein decreases. The minimum value is -5 atm. The pressure at point y approximately matches its average value. Due to the pressure drop in the pressure chamber 2, the surface of the ink (meniscus) from the nozzle 1
At the same time as the ink is drawn, the ink in the ink tank follows the supply path A and is sucked into the pressure chamber 2 and supplied. At that time, the ink pressure in the x part of the supply path A is almost constant and 1 atm. Therefore, as the ink pressure in the opening 6 communicating with the pressure chamber 2 or the ink pressure in the y part decreases, the elastic body 5 It swells in the direction of arrow C. As a result, that portion of the supply path A expands, and the flow path resistance decreases. Ink was able to be supplied to the pressure chamber 2 quickly, and the meniscus was prevented from being drawn deeply from the nozzle 1, and the entry of air bubbles from the nozzle 1 was prevented.

FIG. 4 shows a second embodiment of the ink jet apparatus according to the present invention.
It is sectional drawing for demonstrating an Example. FIG. 5 is a perspective view for explaining a second embodiment of the ink jet device of the present invention. The same parts as the first embodiment are omitted, and only the parts different from the first embodiment will be described. The structure 7 of FIG. 2 is different from the structure 7 ′ of FIG. Thus, unlike the first embodiment, not all of the peripheral portion 101 'of the free portion 100' that is not bonded to the structural material 7 ', but only a part of the peripheral portion 101'.
Not adhered to.

Although the embodiment having the pressure generating element 3 and the movable wall 4 has been described, the present invention can be applied to an ink jet apparatus having no movable wall or the like, for example, a bubble jet type ink jet apparatus.

[0017]

The ink jet apparatus according to the present invention has a pressure chamber and an ink supply path for supplying ink to the pressure chamber, and the ink supply path and the pressure chamber are maintained in communication with the wall surface of the ink supply path. In addition, by disposing the elastic body so that the flow path resistance of the ink supply path can be changed according to the pressure in the pressure chamber, the elastic body can be a pressure generating member without having a complicated structure as in a conventional check valve. Since the flow path resistance in the supply path can be easily and responsively varied by elastically deforming following the driving of the ink jet head, it is possible to provide an ink jet apparatus excellent in ink ejection efficiency at low cost. It has the effect of being able to. Further, the ink jet apparatus of the present invention includes a pressure chamber, and an ink supply path for supplying ink to the pressure chamber, and a part of a structural material that divides the supply path and the pressure chamber includes a pressure chamber according to the pressure in the pressure chamber. An elastic body for increasing or decreasing the flow path resistance of the supply path is arranged, and at least a part of the periphery of the elastic body is not supported by a structural material, so that the elastic body does not have a complicated structure like a conventional check valve. Since only a part of the periphery of the elastic body is elastically deformed following the pressure in the pressure chamber, the flow path resistance in the supply path can be easily and responsively varied, so that the ink ejection efficiency is excellent. The present invention has the effect of providing a low-cost inkjet device. In addition, since the elastic body is arranged in a part of the structural material, the supply path and the pressure chamber are always in communication when the pressure generation in the pressure chamber is in a standby state. Can be filled only with capillary force, and since one end of the elastic body is a free end, when ink is supplied from the supply path to the pressure chamber after the ink is ejected by the pressure generation of the pressure chamber. In this case, the elastic body is elastically deformed in the direction opposite to the direction in which the pressure is generated in the pressure chamber, so that the ink supply speed can be further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a first embodiment of the present invention.

FIG. 2 is a perspective view for explaining a first embodiment of the present invention.

FIG. 3 is a driving signal used in the first embodiment of the present invention.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

FIG. 5 is a perspective view showing a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Pressure chamber 3 Pressure generating element 4 Movable wall 5 Elastic body 6 Opening A Supply path 11 Rising part 12 Hold part 13 Falling part 100 Free part

Claims (3)

(57) [Claims] A pressure chamber; an ink supply path for supplying ink to the pressure chamber; an ink supply path and a pressure chamber maintained in communication with a wall surface of the ink supply path; An ink jet apparatus, wherein an elastic body is arranged so as to vary a flow path resistance according to a pressure in a pressure chamber. 2. A pressure chamber, and an ink supply path for supplying ink to the pressure chamber, wherein a part of a structural material that divides the supply path and the pressure chamber includes the supply path according to the pressure in the pressure chamber. An ink jet apparatus, wherein an elastic body for increasing or decreasing the flow path resistance is disposed, and at least a part of the periphery of the elastic body is not supported by the structural material. 3. The ink jet apparatus according to claim 2, wherein the elastic body does not increase the flow path resistance of the supply path when the pressure in the pressure chamber is in a standby state.