JPH0432282Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ink jet printer having a function of preventing clogging of ink jet nozzles.

[Prior art]

In general, this type of inkjet printer is of the airflow type, in which ink droplets are ejected from an ink reservoir toward the printing paper and are sprayed onto the printing paper using an air stream. By the way, in this type of air flow type, the orifice opens into the air, so when the ink ejecting head is not in use, the ink moisture in the ink reservoir evaporates through the orifice, and the ink components dry and stick to the periphery of the orifice, clogging the orifice. In addition, when the volume of ink decreases due to evaporation of ink moisture, air is sucked into the ink reservoir, causing a failure in the propagation of pressure waves from the diaphragm that drives ink jetting to the ink, resulting in malfunction of ink droplet jetting. There were some drawbacks, such as:

As a means to overcome these drawbacks, a clogging prevention method as shown in FIG. FIG. 3A is a schematic cross-sectional view showing the inkjet printer when it is in use, and FIG. 3B is a schematic cross-sectional view showing the state when it is not in use. Photographic paper is shown wrapped around a rotating drum 60. The ink ejecting head 50 has a head main body 51 in the shape of a thick disk, and a diaphragm 52a on the rear side.
A pressure chamber 52 whose front side is closed with a diaphragm plate 52c, and a front plate 53b formed over the outer periphery and front of this pressure chamber 52 and whose front side is closed with an orifice 53a. It includes an ink reservoir 53 and a ventilation chamber 54 formed over the outer periphery and front of the ink reservoir 53 and closed by a cover plate 54b having a blowhole 54a at a position facing the orifice 53a on the front side. has been done. The pressure chamber 52 is filled with ink, and the ink reservoir 53 is filled with ink tube 53d.
The ventilation chamber 54 is connected to an ink cartridge (not shown) via an ink cartridge, and is filled with ink supplied from the ink cartridge.Furthermore, the ventilation chamber 54 is connected to an air pump (not shown) via an air tube 54d.

Now, when an electric signal is applied to the diaphragm 52a, the vibration of the diaphragm 52a is propagated to the diaphragm plate 52c using the ink in the pressure chamber 52 as a pressure propagation medium, and the vibration of the diaphragm plate 52c is transmitted to the ink reservoir 5.
The ink is propagated as a pressure wave to the ink in the recording medium 3, and the ink is ejected as ink droplets from the orifice 53a, and is sprayed onto the printing paper 61 together with the air flow ejected from the ventilation chamber 54 through the jet nozzle 54a to perform recording.

When not in use, the pad 57 is brought into contact with the nozzle port 54a to close it, as shown in FIG. The ink is supplied to the ventilation chamber 54, and the ink is filled into the ventilation chamber 54 at least to a height above which the orifice 53a is submerged.

In this state, since the orifice 53a is submerged in the ink, the orifice 53a will not dry out and become clogged, and even if a mechanical shock is applied, the ink reservoir 53 will not be filled through the orifice 53a. This eliminates inconveniences such as air being sucked in.

[Problem that the invention attempts to solve]

By the way, in the conventional product as described above, when filling ink into the ventilation chamber 54 as shown in FIG.
Air bubbles A remain in the ventilation chamber 54, and when the ink in the ventilation chamber 54 is discharged to resume printing, the pressure balance between the inside and outside of the orifice 53a is disrupted and air enters the ink reservoir 53. There was a problem in that the vibration propagation function was degraded due to volumetric shrinkage, and ink could not be ejected accurately.

As shown in FIG. 4A, air bubbles A enter the ventilation chamber 54.
There are various possible reasons for this remaining, one of which is as follows. That is, when ink is ejected from the orifice 53a into the ventilation chamber 54, the ink droplets first flow outward in a strip between the front plate 53b and the cover plate 54b, and reach the outermost periphery of the ventilation chamber 54. Ink begins to accumulate in the formed groove, and is then supplied to the groove through the path a of the initially formed striped portion, filling the entire ink. As a result, the air tube 54d connected to the groove-shaped portion is substantially blocked by ink. Therefore, even if you try to fill in the part b trapped between the strip-shaped passages a inside the groove-shaped part with ink,
Since the area around the area is surrounded by ink and air is prevented from being discharged, the ink is not filled, and the ink supplied from the orifice 53a simply flows backward through the air hose 54d.

In this way, there is no exhaust path for the air existing in the part b sandwiched between the strip-shaped passage a inside the groove, so that the air existing in that part is not exhausted to the outside of the ink ejecting head but instead It ends up staying between the face plate 53b and the cover plate 54b.

In addition to this, it is known that similar results may occur if ink drips from the orifice 53a in a strip along the front plate 53b into the ventilation chamber 54 due to an operation error of the diaphragm plate 52c. The occurrence rate is particularly high when the front plate 53b has high water repellency.

[Means for solving problems]

The present invention was developed in view of the above circumstances, and its purpose is near the orifice that ejects ink droplets from the ink reservoir.
A recess is formed in the part facing the ventilation chamber, and when the ink is filled into the ventilation chamber, ink accumulates inside the recess and the orifice is positioned in the ink, effectively filling the surrounding area including the orifice with less ink. To provide an inkjet printer equipped with an inkjet head which can be maintained in a submerged state to prevent clogging and can certainly prevent air bubbles from remaining.

The inkjet printer according to the present invention uses the vibration of the diaphragm to eject the ink in the ink reservoir as ink droplets into the ventilation chamber through the orifice, and to the outside from the nozzle along with the wind in the ventilation chamber. In the inkjet printer, the ink is filled from the ink reservoir in the vicinity of the orifice on the side wall surface of the orifice that opens facing the ventilation chamber, and the ink is expanded in a planar manner in the ventilation chamber. It is characterized by having a rough surface or a concave portion formed therein.

〔Example〕

The present invention will be specifically explained below based on drawings showing embodiments thereof. Figure 1 is a schematic sectional view of the ink jet printer according to the present invention (hereinafter referred to as the product), Figure 2 A and B are enlarged sectional views of the ink jet head when it is in use, and Figure 2 C is an enlarged sectional view of the ink jet head when it is not in use. 1 is an enlarged cross-sectional view, in which reference numeral 1 indicates an ink ejecting head, reference numeral 10 indicates a rotating drum, and reference numeral 11 indicates printing paper wound around the rotating drum. The ink ejecting head 1 has a head main body 51 in the shape of a thick disk, and a pressure chamber 2 whose rear side is closed by a diaphragm plate 2a and whose front side is closed by a diaphragm plate 2c equipped with micro holes for pressure regulation. , formed over the outer periphery and front of this pressure chamber 2,
The front side includes the orifice 3a and the orifice 3a.
an ink reservoir 3 closed by a front plate 3b having an annular groove 3f around the ink reservoir 3;
The ventilation chamber 4 is formed over the outer periphery and the front of the vent and is closed by a cover plate 4b having a blowhole 4a at a position facing the orifice 3a on the front side. The groove 3f formed on the front surface of the front plate 3b is set to a depth such that when ink is injected into the ventilation chamber 4, the ink easily accumulates in the groove 3f, and when this function is provided. It does not matter what the cross-sectional shape is. The pressure chamber 2 is filled with ink, and the ink reservoir 3 is connected to a bag body 5a containing ink in an ink cartridge 5 via a communication path 3c, an ink tube 3d, and a filter (not shown). The ventilation chamber 4 is filled with ink supplied from the bag body 5a.
is connected to the air pump 6 via an air tube 4d and a switching valve 4e interposed therebetween,
Pressurized air from an air pump 6 is introduced. The air pump 6 is separately connected to a housing 5b that houses the bag 5a of the ink cartridge 5 via an air tube 4d, and pressurized air is introduced into the housing 5b from the air pump 6, so that the ink in the bag 5a is mixed with the bag 5a. A pressure corresponding to the water head of the orifice 3a is applied. Now, when an electric signal is applied to the diaphragm 2a, the vibration of the diaphragm 2a is propagated to the diaphragm plate 2c using the ink in the pressure chamber 2 as a pressure propagation medium, and the vibration of the diaphragm plate 2c is transmitted to the ink in the ink reservoir 3. The ink is propagated as a pressure wave and is ejected as ink droplets from the orifice 3a as shown in FIG.
The air is blown onto the printing paper 11 along with the air flow ejected from the jet through the jet nozzle 4a, and recording is performed. On the other hand, the ink consumed during recording is transferred to the bag body 5 by surface tension acting on the orifice 3a of the ink reservoir 3.
The ink is supplied to the ink reservoir 3 from a.

In this state, ink does not accumulate in the groove 3f on the front surface of the front plate 3b, as shown in FIG.
Or, as shown in Figure 2B, the groove 3 will be partially filled.
f has no effect on anything else.

On the other hand, when not in use, the pad is brought into contact with the blowhole 4a to close it, as shown in FIG. Pressurized air is introduced into the housing 5b, and the diaphragm 2a is actuated while introducing the ink in the bag body 5a into the ink reservoir 3. As shown in FIG.
supply to. Therefore, by providing the groove 3f at the above-mentioned position, the ink jetted from the orifice 3a flows outward in a strip between the narrow front plate 3b and the cover plate 4b, as shown in FIG. 2D. Flows to reach the groove 3f, and while filling the groove 3f, expands inside the groove 3f in a strip shape in the circumferential direction,
When the inside of the groove 3f is filled with ink, this groove 3f
Ink begins to accumulate towards the inside surrounded by.

At this time, even if the ink ejected from the orifice 3a reaches the concave groove 3f in a strip between the narrow front plate 3d and the cover plate 4b, the orifice 3a
When the inside of the groove 3f including the air tube 3f and the inside surrounded by the groove 3f are filled with ink, the air inside the groove 3f is transferred to the outside of the groove 3f connected to the air tube 4d. air bubbles are not trapped.

When the inner side surrounded by the groove 3f including the orifice 3a is completely filled with ink, the ink jetting from the orifice 3a is stopped, resulting in the state shown in FIG. 2C.

In the above-described embodiment, the groove 3f is formed in a ring shape around the orifice 3a on the front surface of the front plate 3b around the orifice 3a. However, the cross-sectional shape and the plane of the groove 3f itself The shape is not particularly limited, and for example, a large number of partial recesses may be arranged in a ring shape. Further, instead of the groove 3f, the surface of the front plate 3b around the orifice 3a may be formed into a rough surface where ink tends to stay.

In this state, the orifice 3a is submerged in the ink, so the orifice 3a will not dry out and become clogged, and even if a mechanical shock is applied, the ink pool 3 will be removed through the orifice 3a.
This eliminates inconveniences such as air being sucked into the interior. Furthermore, when air is supplied from the air tube 4d when printing is resumed, a uniform pressure is applied from around the groove 3f, and ink is discharged to the outside through the jet nozzle 4a. Note that some of the ink is
Although it may remain in the groove 3f as shown in Figure B, it does not cause any trouble.

〔effect〕

As described above, in the present invention, since a recess is formed in the part facing the ventilation chamber around the orifice, when the ventilation chamber is filled with ink when not in use,
The ink accumulates in the recess and the ventilation chamber around the orifice can be reliably filled with ink, so only a small amount of ink is required, and it does not trap air bubbles, reliably preventing air bubbles from entering the ink reservoir. The present invention has excellent effects, such as being able to maintain accurate ink ejection function.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of the proposed product, Figure 2 A,
B and C are enlarged sectional views showing the state when not in use and in use, FIG. 2 D is a plan view taken along the K-N line in FIG. FIG. 4 is an explanatory diagram of a state in which bubbles are sealed in a conventional product. 1... Ink ejection head, 2... Pressure chamber, 3...
...Ink reservoir, 3f... Concave groove, 4... Ventilation chamber, 5
...Ink cartridge, 5a...Bag body, 6...
Air pump, 10... drum, 11... printing paper.

Claims (1)

[Claim for Utility Model Registration] Vibration of the diaphragm causes the ink in the ink reservoir to be ejected as ink droplets into the ventilation chamber through the orifice, and is ejected from the nozzle to the outside along with the wind in the ventilation chamber. In the inkjet printer that is configured to fill ink from the ink reservoir, the ink is expanded in a planar manner in the ventilation chamber near the orifice on the side wall surface of the ventilation chamber of the orifice that opens facing the ventilation chamber. rough surface,
Or an inkjet printer characterized by forming a recessed part.