JPH0688416B2 - Inkjet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to air bleeding of a recording head of an ink jet recording apparatus, and more particularly to an ink jet recording apparatus which evacuates an ink liquid chamber in the recording head by negative pressure suction.

[Prior art]

Conventionally, a recording head of such an ink jet recording apparatus is provided with a common ink liquid chamber for a plurality of nozzles, and this ink liquid chamber moves with the head as the carriage moves to perform printing. It is being appreciated. An air layer is provided in the ink liquid chamber in order to mitigate the impact force such as the direction change of the carriage, and this air layer absorbs the instantaneous increase in the ink pressure in the nozzle at the time of carriage return to the nozzle. It has a buffering effect that can minimize the applied pressure. To achieve this effect, the amount of air layer is usually set to about 0.1 to 0.3cc. In order to keep this air layer constant, conventionally, the air bleeding means shown in FIGS. 1 and 2 has been required.

That is, in FIG. 1, a carriage 2 is equipped with a head 1 having a plurality of nozzles arranged in a line, and the carriage 2 is configured to be capable of reciprocating on a shaft 3. Further, the recording head 1 is provided with an ink liquid chamber for supplying ink to the nozzles, the ink 6 is supplied from the ink supply pipe 4 to the ink liquid chamber, and the above-mentioned air layer 7 is formed. In order to secure the liquid surface of the air layer 7 and the ink 6, that is, to keep the volume of the air layer constant, an air bleeding tube 5 is provided which is connected to the air bleeding means and travels together with the carriage.
This tube is a flexible plastic, and since ink easily evaporates and moves, the arrangement thereof becomes complicated.

Further, as another air bleeding method, one in which a ventilation valve 8 as shown in FIG. 2 is provided is known. This vent valve 8 is normally fixed by a seal member 9 which is fixed to the air layer 7 and the ink 6
Is sealed. When the air that has entered due to the evaporation of ink increases the air layer, the ventilation valve 8 is pushed down in the direction of the arrow against the biasing force of the spring 8b to push up the ink surface from the ventilation hole 8a and remove the air. However, with such a structure, it is very difficult to visually observe the rising surface of the ink, and there is a drawback that the leaked ink is likely to contaminate the surroundings.

〔Purpose〕

Therefore, the present invention is made in order to eliminate the above-mentioned conventional drawbacks, and a certain volume of air layer is ensured in the ink liquid chamber to surely perform air bleeding, and at the same time, the air that has entered the nozzle is also made sure. It is an object of the present invention to provide an ink jet recording device that can be discharged to the inside.

An ink jet recording apparatus for achieving the above-mentioned object opens a discharge port for discharging ink, an ink chamber for storing ink discharged from the discharge port, and the ink chamber to the outside by a pressure difference. A valve, a cap having a cover for independently covering the discharge port and the valve,
Suction means for generating negative pressure for sucking ink from the discharge port and air from the valve,
A first connecting path connecting the discharge port side cover and the suction means, and a second connecting path connecting the valve side cover and the suction means.
And a switching means that is provided in the second connecting path and switches the action of negative pressure on the valve.

By adopting such a configuration, it is possible to appropriately perform air bleeding and ink suction, and it is possible to maintain a good ink ejection state.

Further, since the air in the ink chamber can be adjusted at the same time as the nozzle recovery operation, it can be reliably performed without requiring a special device or a detection mechanism.

〔Example〕

Hereinafter, the present invention will be described specifically and in detail with reference to the drawings.

Embodiments of the present invention are shown in FIGS. 3 to 8. The same parts as those shown in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. FIG. 3 is a sectional view of the recording head 1 of the present invention, in which an air vent valve portion is provided at the boundary between the ink 6 and the air layer 7. Usually a valve of elastic member 10
Is close to the valve seat 1C, and is configured to separate from the valve seat 1C and communicate with the air layer 7 through the vents 1D and 1B when negative pressure is transmitted from the vent 1D. The nozzle portion 1A is provided below the ink 6. FIG. 4 is a front view from the nozzle portion side of FIG. FIG. 5 shows a state in which the ejection port at the tip of the nozzle unit 1A of the recording head 1 of FIG. As shown in FIG. 6, the cap 11 is made up of a hollow air-bleeding elastic member 11A and a nozzle portion elastic member 11B. . A switching valve 13 is provided in the middle of the air bleeding suction tube, and its sectional view is shown in FIG. Solenoid 16
The iron core 16A moves together with the elastic valve 16B in the inside of the valve, and the spring 17 normally closes the air extraction / suction tube.
Only when 16 is turned on, the negative pressure source 15 and the air bleeding elastic member 11A communicate with each other.

The reason why the switching valve 13 is required is that the flow passage resistance is extremely low as compared with the flow passage resistance of the nozzle portion so that the air layer 7 of the ink liquid chamber can easily escape due to the negative pressure. For this reason, if air is constantly evacuated and suction is performed from the nozzles, the amount of ink suctioned from the nozzles may decrease, and it may not be easily recovered when air or the like enters the nozzles.

From the above, in order to make it possible to sufficiently suck the ink from the nozzles, at the timing as shown in FIG.
After moving to the direction of the arrow in the figure and making the nozzle part and the vent hole closed, that is, the ON state, turn on the switching valve, that is, connect the air bleed suction tube, then turn the negative pressure source to the ON state and record with the negative pressure. Ink ink and air from inside. 8th
In the figure, (a) is a switching valve, (b) is a negative pressure source, and (c).
Indicates the timing of the cap. The air suction tube side has a very small flow resistance, so it is blocked in a short time, but the nozzle side is further sucked to surely remove bubbles and the like in the nozzle. Further, the communication between the negative pressure source 15 and the nozzle portion may be repeated ON and OFF as shown by the dotted line in FIG. 8, and can be appropriately selected depending on the configuration with the negative pressure source. Finally, the cap is opened and the recording head is in a printing state.

Further, the communication between the negative pressure source connected to the waste ink tube 18 and the cap portion is not limited to the one shown in FIG. 5, but a switching valve is provided for both the air suction tube and the nozzle suction tube to arbitrarily perform air suction and nozzle suction. You can also do it.

〔effect〕

As described above, according to the present invention, a valve mechanism that opens by negative pressure is provided in the air layer part of the ink liquid chamber in the recording head, and the same cap can be surely and quickly deflated with the nozzle part. Further, even if the ejection failure due to air bubbles or the like in the nozzle is blocked by the switching valve, the ink ejection or the like can be sufficiently sucked and discharged from the nozzle, so that the ejection failure of the nozzle portion can be reliably eliminated.

Further, the ink sucked from the air bleeding tube or the like also moves positively to the negative pressure source side due to the negative pressure, and the discharged ink can prevent contamination.

[Brief description of drawings]

1 and 2 are schematic explanatory views of a conventional recording head portion, FIG. 3 is a schematic sectional view of the recording head of the present invention, FIG. 4 is a schematic front view thereof, and FIG. Overall configuration diagram, No. 6
Figure is a front view of the cap, Figure 7 is a sectional view of the switching valve,
FIG. 8 is a timing diagram. 1 ... Recording head, 1A ... Nozzle part, 1B ... Vent hole, 1C ... Valve seat, 1D ... Vent hole, 2 ... Carriage, 3 ... Shaft, 4 ... Ink supply pipe, 5 ... Air vent tube, 6 ... Ink, 7 ... Air layer, 8 ... Vent valve, 8a ... Vent hole, 8b ... Spring, 9 ... Seal member, 10 ... Valve, 11 ... Cap, 11A ... Air venting elastic member, 1
1B: Nozzle elastic member, 12A, 12B ... Air bleed suction tube, 13 ... Switching valve, 14 ... Nozzle suction tube, 15 ... Negative pressure source, 16 ... Solenoid, 16A ... Iron core, 16B ... Elastic valve, 17 ...
Spring, 18 ... Waste ink tube.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B41J 2/185 8306-2C B41J 3/04 102 Z

Claims (1)

[Claims] 1. A discharge port for discharging ink, an ink chamber for storing ink discharged from the discharge port, a valve for opening the ink chamber to the outside by a pressure difference, the discharge port and the valve. A cap having a cover for respectively independently covering the ink, a suction means for generating a negative pressure for sucking ink from the discharge port and air from the valve, and the discharge port side cover. A first connecting path that connects the portion and the suction means, a second connecting path that connects the valve-side covering portion and the suction means, and a second connecting path that is provided in the second connecting path An inkjet recording apparatus comprising: a switching unit that switches the action of pressure.