JPH048234B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet device having a plurality of ink containers of different colors.

Generally, in a closed type ink container, air increases due to evaporation of the ink inside the container, and normal ink supply becomes impossible. Therefore, the increased air is discharged to the outside. For example, if the sub-tank has a sealed structure, the main tank compensates for the volume loss consumed by ink ejection, and the ink is supplied from the main tank by pressure using the swinging of the tube, an air vent hole is installed. is necessary, and the air increased by evaporation must be discharged outside the subtank. When this increased air is discharged by a suction negative pressure source, ink is also suctioned together with the air, so if the air vent tube communicates with multicolor ink, the ink will spread and mix colors. In order to avoid this, a conventional arrangement has been made, for example, as shown in FIG. In the figure, reference numeral 1 denotes a recording head which is made up of a plurality of sub-tanks storing inks of different colors, and each sub-tank houses an inkjet nozzle. A main tank 2 (only one is shown in the figure) is connected to each sub-tank. A cap 3 seals the surface of the recording head 1 where the nozzle ejection ports are provided to prevent the ink from drying out. Reference numeral 4 denotes a negative pressure source, which is connected to an independent air vent tube 5 to each sub-tank.

In this way, if the air vent tube 5 is provided individually for each tank, color mixing of ink can be prevented to some extent. However, since each ink is mixed within the negative pressure source, for example, if the air vent tube 5 is clogged with ink, the ink will diffuse and mix colors.

Further, even if there is an air layer in the air vent tube 5, an ink water head is generated due to inclination, temperature change, etc., and ink moves due to a change in air volume, resulting in color mixing of the inks.

The main object of the present invention is to solve the problems caused by ink mixing that may occur when air is sucked from the ink reservoirs that store the respective inks in an inkjet device that uses a plurality of different inks as described above. That is, the purpose is to solve the problem that recording with original ink may be disturbed.

An inkjet device of the present invention that achieves this object includes: a plurality of ink reservoirs each storing ink to be supplied to a plurality of ejection ports that eject different inks, and an inkjet device commonly provided to the plurality of ink reservoirs. , a suction means for sucking air from the plurality of ink reservoirs, a plurality of suction paths for respectively flowing the air sucked from the plurality of ink reservoirs by the suction means, and the plurality of suction paths collectively as described above. A path having a guide path leading to a suction means; and a blocking means for cutting off communication between the plurality of ink reservoirs and the guide path when suction is not being performed by the suction means. shall be.

Embodiments of the present invention will be described in detail below with reference to FIG. 2 and subsequent figures.

In FIG. 2, 9 is an ink supply tube 8-
1 to 8-4, a capping 12 having an ink suction path 11 and an air suction path 25 is disposed in an elastic cap 10 facing the recording head, and a pin 12A is protruded from the side surface of the capping 12. has been done. Further, a suction path blocking mechanism shown in FIGS. 4A and 4B is built inside. The lever 13 moves up and down in the direction shown by the arrow 14, and the grooved cam 13B provided on the lever 13 engages with the pin 12A, thereby converting the vertical movement of the lever 13 into a longitudinal movement of the capping 12. The close contact with and release from the recording head 9 is controlled.
The lever 13 is further provided with an opening/closing cam 13A, and its vertical movement opens the ink hollow shaft 15 and the air hollow shaft 26 (third
(Figure) in the direction of arrow 16. Furthermore, a negative pressure source 17 is disposed directly below one end of the lever 13, and by moving the lever 13 up and down, a piston 18 of the negative pressure source 17 is moved up and down. Negative pressure source 1
7 and the capping 12 are connected by an ink suction tube 19 and an air vent tube 20, whereby negative pressure is transmitted.

FIG. 3 shows a partial cross section of FIG. The recording head 9 has a structure in which four sub-tanks 9-1, 9-2, 9-3, and 9-4, which are ink storage parts, are integrated in parallel in the direction of movement with respect to the printing paper (printing direction). Each sub-tank has ink of a different color, an ink jet nozzle 21, and an air vent hole 22, and a resistance filter 23 is fitted at the tip of each air vent hole. The nozzle 21 is of a so-called ink-on-demand type, and ejects ink in response to a drive signal supplied from a printer circuit (not shown). The resistance filter 23 is capable of keeping the inside of each sub-tank in a substantially airtight state, and is also used to extract excess air from inside the tank and keep the ink level constant. In order to achieve these two functions, the resistance filter 23 is made of a material such as a membrane filter having pores of about 5 to 10 microns. This filter has the property of allowing almost no ink to pass through, only allowing air to pass through, and furthermore, when ink is attached to it, air does not pass through either. As shown in the figure, the normal ink level is 24
At this time, the resistance filter 23 is wet with ink and keeps the inside of the tank in a sealed state. Further, when air increases in the tank due to evaporation of ink, etc., the liquid level decreases to 24A. In this position, the resistance filter 23 will not get wet with ink.
Air can pass freely to some extent. The capping 12 has four ink suction passages 11 and four air suction passages 25 corresponding to each nozzle and air vent hole. Each of the four ink suction passages 11 is connected to an ink hollow shaft 15 within the capping 12, and the four air suction passages 23 are connected to an air hollow shaft 26 within the capping.

FIG. 4A shows a cross section of the hollow shaft 15 for ink.

It has a notch 15A corresponding to each ink suction passage 11, and the open end of the hollow shaft 15 is connected to the ink suction tube 1.
9 communicates with a negative pressure source. In the state shown in FIG. 4A, the opening/closing cam 13A of the lever 13 pushes the abutment 15B of the hollow shaft 15 and moves it to the position 15C in FIG. 4B, thereby sucking ink from the nozzles 21 of each color. When the hollow shaft abutment 15B is returned to the position 15C' by the spring 27 due to the upward movement of the lever 13, each ink suction path 11 is blocked.
That is, the hollow shaft 15 moves in the upward direction of the arrow 28, and the positions of the notch 15A and the ink suction path 11 no longer match, so the ink suction path 11 is blocked. Further, the same effect is produced as a mechanism in which the hollow shaft 15 rotates to shut off the ink supply path 11.

The air hollow shaft 26 is also formed in exactly the same way as the ink hollow shaft 15, although it is not shown in the figure. That is, a notch that connects each of the four air vent holes 22 to a negative pressure source, and an opening/closing cam 1 of the lever 13.
3A, and a spring that presses the abutment against the cam 13A. When the lever 13 is pushed down, each air suction path 25 communicates with a negative pressure source, and air can be sucked from the filter 23. be. Incidentally, at this time, a small amount of ink is sucked through the filter 23. Air hollow shaft 26 and air suction tube 20
As a result, a guide path is formed that connects each air suction path 25 to the negative pressure source 17, which is a suction means. Each air suction path and guide path forms a path through which air sucked from the ink reservoir by the suction means reaches the suction means. Further, when the lever 13 is returned to the state shown in FIG. 2 by the spring, communication between the plurality of ink reservoirs and the guide path via the air suction path 25 is cut off, and the ink between the suction paths is interrupted. Color mixing is prevented. Note that when the lever 13 is pressed down, the ink suction path 11 is first connected to the negative pressure source, but if the position and size of the notch are taken into account, the air suction path can be connected to the ink suction path at the same time. It is clear that it can be done.

FIG. 5 shows the negative pressure source 17. Negative pressure source 17
has a piston 18 that can move up and down inside;
O-rings 30A, 30 required to maintain airtightness
B, 30C, valve 31 that opens during exhaust, and piston 1
A spring 32 having a biasing force for pushing up the piston 18 upward, and pump suction ports 34, 34 provided at positions that can communicate with the low pressure space 33 formed when the piston 18 moves downward. One ends of an ink suction tube 19 and an air suction tube 20 are connected to the pump suction ports 34, 34, respectively. Due to this configuration, the lever 13 is moved as indicated by the arrow 14.
When the cap 12 is moved downward, the pin 12A integrated with the capping 12 is advanced by the grooved cam 13B, and the elastic cap 10 is pressed against the front surface of the recording head 9, that is, the surface where the nozzle and the air suction hole are located, to seal it. Thereafter, the piston 18 of the negative pressure source 17 is pressed by the lever 13, the space 33 expands, and the pump suction port 34,
34, negative pressure is generated inside the hollow shafts 15 and 26, and immediately after this, the opening/closing cam 13A is moved to the fourth
The ink suction path 11 and the air suction path 25 are placed in the position shown in Figure A, and the ink suction path 11 and air suction path 25 are communicated with a negative pressure source to suck ink and air to remove the cause of defective printing in the nozzle and excess air in the tank. Note that when there is a large amount of air in the tank, that is, when the ink level is at 24A in Figure 3, the filter 23 is not wet with ink, so sufficient air passes through it, excess air is sucked, and the inside of the tank is The liquid level is at the normal position 2
Recovers to 4. On the other hand, when the amount of air in the tank is normal, the filter 23 is wetted with ink, so almost no air passes through it, and the ink level hardly rises. Further, inside the tank, the amount of ink that has been absorbed is supplied from a main tank (not shown).

When the lever 13 is pushed down to the position indicated by the dotted line 13D in FIG. 2 to suck in ink and air, and the depression is stopped, the piston 18 is returned by the spring 32, and the lever 13 is also returned to the position indicated by the two-dot chain line 13C.
At this time, the opening/closing cam 13A also moves upward, so the ink hollow shaft 15 moves to the position 15C in FIG. Move to the position where 25 is blocked. On the other hand, when the lever 13 comes to the position 13C, the respective abutments of the ink hollow shaft and the air hollow shaft are in contact with the straight part of the grooved cam 13B, and the capping 12 seals the front surface of the head 9. Since the biasing force of the spring 32 disappears at this position, the lever 13 stops at this position. Therefore, by pressing down the piston 18, ink,
After suctioning the air, when the piston 18 is released, the capping 12 seals the tip of the head 9, and at this time, the ink hollow shaft 15 and the air hollow shaft 26 block the ink suction path 11 and the air suction path 25. Therefore, even if you leave it in this state, the ink will not mix colors.

Note that the ink suction path 11 and the air suction path 25
is shut off in the state shown in FIG. 5, that is, in the state in which the negative pressure once obtained in the space 33 is generated in each tube, and in addition, the pump suction ports 34, 34 are present between the O-rings 30B and 30C. Since the ink in the ink suction tube 19 and the air suction tube 20 is on the negative pressure source side, backflow is prevented, and the mixed color ink contaminates the inside of the ink suction path 11 and the air suction path 25. Never.

The capping can be opened by pushing up the lever 13 to the state shown in FIG. 2 using an external force not shown.

FIG. 6 shows the suction operation described above. When the capping 12 seals the tip of the head, the suction operation has not yet started, and when the lever 13 is subsequently pressed, the ink is suctioned and the air is Starts slightly later than ink suction. After the lever 13 reaches the lowest position 13D, when the lever is released, the lever 13 returns upward due to the force of the spring 32, but even at this time, negative pressure is always applied to the ink suction path 11 and the air suction path 25. This is because the valve 31 of the negative pressure source 17 is made of a thin film, and the resistance due to this valve is smaller than the air flow resistance at the pump suction port 34. Therefore, the suctioned ink is not pushed back when the lever 13 returns, but rather the suction paths 11 and 25 are blocked by the ink hollow shaft 15 and the air hollow shaft 26 while being suctioned with further negative pressure. Note that each sub-tank is supplied with lost ink from a main tank (not shown), and the pressure is balanced.

Note that the present invention is applicable not only to sealed ink containers, but also to
An ink container that is open to the atmosphere may also be used.

As is clear from the above description, even if a mechanism is provided for sucking air from each of the ink tanks storing a plurality of different inks, the present invention provides means for blocking the suction paths from each other in accordance with the operation of the suction means. Since mixing of the respective inks can be prevented, stable recording can be achieved by ejecting the original ink from each ejection port.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an overview of a conventional example, Fig. 2 is an external perspective view of an embodiment of the present invention, Fig. 3 is a partial sectional view of Fig. 2, and Fig. 4A is a diagram of a suction cutoff mechanism. 4B is an operation explanatory diagram showing the mutual relationship between the vertical movement of the opening/closing cam and the hollow shaft, FIG. 5 is a sectional view showing details of the negative pressure source used in the embodiment, and FIG. 6 is a timing chart. It is a diagram. 9...Recording head, 12...Capping, 1
5... Hollow shaft for ink, 17... Negative pressure source, 21...
...Inkjet nozzle, 22...Air vent hole,
26...Hollow shaft for air.

Claims (1)

[Scope of Claims] 1. A plurality of ink storage sections each storing ink supplied to a plurality of ejection ports that eject different inks; a suction means for suctioning air from the storage section; a plurality of suction paths through which the air sucked from the plurality of ink storage sections by the suction means flows; and the plurality of suction paths collectively leading to the suction means. An ink jet device comprising: a passage having a guide passage; and a blocking means for cutting off communication between the plurality of ink reservoirs and the guide passage when suction by the suction unit is not performed. 2. The inkjet device according to claim 1, wherein the suction means is a suction pump. 3. The guide path is formed using a hollow shaft having a plurality of suction holes corresponding to the plurality of suction paths, and the blocking means is configured such that the plurality of suction paths and the plurality of suction holes do not correspond to each other. The inkjet device according to claim 1, wherein the communication is interrupted by moving the hollow shaft to a position. 4. The ink ejected from the plurality of ejection ports is
An inkjet device according to claim 1, each having a different color.