Method for filling ink to head unit

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to an inkjet recording device that ejects ink droplets from a nozzle to write a recording image of characters or the like on a recording medium, and more specifically, to a method of filling ink in an inkjet recording device in which an ink tank is mounted on a carriage. ..

【0002】

[Conventional technology]

Inkjet recording devices that eject ink droplets from nozzles to write information on recording paper can be broadly divided into two types: a type in which ink tanks are provided at appropriate locations in the device body and ink is supplied to the head unit by a tube. There are two types, one that is housed in the carriage that is equipped with. The latter type, in which the ink tank is mounted on the carriage, does not require the ink supply pipe to be routed, but on the other hand, the ink tank is installed in the limited space of the carriage, which imposes various restrictions on the structure of the ink flow path. There is a disadvantage that it is difficult to suppress the bubbles that are likely to be generated when the ink is supplied from the tank to the head unit, and it is difficult to remove the generated bubbles.

【0003】

[Problems to be Solved by the Invention]

The present invention has been made in view of such a problem, and an object of the present invention is to propose a method of filling an ink into a head unit, which can prevent bubbles from entering the head unit. ..

【0004】

[Means for solving problems]

In order to solve such a problem, in the present invention, a head unit that ejects ink droplets in response to a print signal, an ink tank that supplies ink to the head unit, and the head unit and the ink tank are connected. In a method of filling ink in an inkjet recording apparatus including a filter member provided in a flow path and a cap member detachably configured in the head unit and communicated with a suction pump, the head unit is attached by the cap member. After the capping step of sealing, the intermittent suction step of intermittently driving the suction pump to suck ink from the head unit, and the intermittent suction step, the suction pump is continuously driven to the head unit. It is provided with a continuous suction step of sucking ink from the ink.

【0005】

[Action]

Since the ink flow rate is extremely low at the time of initial filling, foaming in the ink flow path is suppressed to be small even when no liquid is present in the ink flow path, and the amount of ink required for subsequent bubble discharge is minimized.

【0006】

[Example]

Therefore, the details of the present invention will be described below based on the illustrated examples. FIG. 1 shows an embodiment of a recording device to which the ink filling method of the present invention is applied. Reference numeral 1 in the drawing is an inkjet head unit, which is connected to an ink tank 3 via a connecting member 2. The ink absorbed in the foam 11 of the ink tank 3 is sucked out by the hollow needle 9, and the ink droplets are ejected in accordance with the recording signal while being supplied through the ink supply flow path 13 of the connecting member 2. Is.

【0007】

FIG. 2 shows an example of the above-mentioned head unit 1, in which reference numeral 20 is a reservoir that receives ink from a rising pipe 15 connected to the ink supply path 13, and is via an ink supply port 21. Ink is supplied as much as the ink consumed in each pressure generating chamber 22. The diaphragm 23 that seals the pressure generating chamber 22 is provided with the tips of the piezoelectric vibrators 24, 24, 24 .... in contact with each other corresponding to the pressure generating chambers 22, 22, 22 .... Has been done. The piezoelectric vibrators 24, 24, 24 .... expand and contract in response to a recording signal to reduce and expand the volume of the pressure generating chamber 22 so that ink is sucked from the reservoir 20 into the pressure generating chamber 22. Ink droplets are ejected from the nozzle opening 27 of the nozzle plate 26.

【0008】

Returning to FIG. 1 again, reference numeral 4 in the drawing is a cap member arranged in a non-printing area, which abuts on the nozzle plate 26 of the head unit 1 by a drive mechanism (not shown) and has nozzle openings 27, 27, 27 ... It prevents the drying of the. The cap member 4 is connected to the suction pump 5 by a tube 12, and is configured to perform an ink suction operation by the control device 6. As the pump 5, for example, a plurality of rollers arranged so as to be on the same circumference at intervals on the support are brought into contact with elastic tubes arranged in a circle, and the support is unidirectionally driven by a DC motor. A so-called tube pump that rotates can be used. Reference numeral 10 in the figure indicates a waste ink tank connected to the discharge port of the pump 5 by the tube 13.

【0009】

FIG. 3 shows an embodiment of the structure of a carriage equipped with the above-mentioned head unit and tank, in which reference numeral 30 is a carriage that is guided by a guide lock 31 and reciprocates along a platen (not shown). An ink tank holder 32 for holding the ink tank 3 is provided on the upper surface of the ink tank holder 32, and a lever-33 that engages with the engaged portion of the ink tank 3 to support and fix the ink tank 3 rotates. It is freely supported.

【0010】

FIG. 4 shows a structure in which the ink tank 3 is mounted on the head unit 1 mounted on the carriage 30 via the connecting member 2, and the connecting member 2 includes the ink tank 40 and the head unit 20. The head unit 1 is intervened between the two, and the downward force generated when the ink tank 40 is mounted is not applied to the head unit 1, and the head unit 1 is surely engaged with each other while absorbing the positional deviation between the two.

【0011】

As shown in FIG. 5, the connecting member 2 has a substantially U -shaped planar shape, and the ink tank 3 is located in the center of the upper surface of the main body 42 that connects the legs 41 and 41 on both sides. A tubular portion 44 that receives the communication pipe 43 of the main body 42 is attached, and a first ink supply path 45 in a horizontal direction is provided from the inner side surface 42a of the main body 42 to the center of the tubular portion 44, which matches the ink supply path 45. A hollow needle 9 inserted into the ink supply port 42 of the ink tank 3 is projected upward at the center of the cylinder portion 44. The through hole 50 of the hollow needle 9 and the first ink supply path 45 are connected by a second ink supply path 47 provided vertically.

【0012】

Reference numeral 51 denotes a filter member formed in a flow path connecting the hollow needle 9 and the second ink supply path 47. A thin line of SUS is formed by twill folding to about 2000 mesh, as shown in FIG. A hole for the hollow needle 9 is stretched between a tapered recess 52 formed in the main body of the connecting member and having an upper portion that expands, and a tapered recess 53 formed below the hollow needle 9 that expands downward. It is arranged so as to be orthogonal to the vertical ink supply flow path formed by connecting 50 and the second ink supply path 47. The taper angles θ1 and θ2 of these recesses 52 and 53 are selected to be about 30 to 60 degrees, and have a function of effectively guiding the air bubbles in the tapered recesses 52 and 53 upward to the through holes 47 or 50. ing.

【0013】

FIG. 7 shows the manufacturing method of the filter member 51 described above, and reference numeral 80 in the drawing is a recess formed in the opening of the tapered recess 52 formed in the connecting member main body 42a, and is a hollow which will be described later. The diameter is selected so that it can engage with the bottom surface of the needle 9, and a tapered concave portion 52 is formed in the center of the diameter, and a ring-shaped convex portion 82 is formed in the step portion 81 so as to surround the tapered concave portion 52. There is.

【0014】

When the filter member 51 is placed on the ring-shaped convex portion 82 ((I) in the figure) and the heat source is pressed against the convex portion 82 via the filter member 51 in this state, the molten portion 82'of the convex portion 82 is formed. It is selectively melted and penetrates into the gaps in the mesh of the filter member 51 (Fig. (II)).

【0015】

On the other hand, in the hollow needle 9, a flange 86 in contact with the upper surface 87 of the connecting member 42 is formed in the vicinity of the bottom portion 85 that can be fitted into the recess 80 of the connecting member 42. On the bottom surface of the flange 86, an annular groove 88 is formed on the inside and an annular protrusion 89 having a V-shaped cross section is formed on the outside.

【0016】

When the hollow needle 9 is inserted into the recess 52 in which the filter member 51 is welded ((III)) and the flange 86 is irradiated with ultrasonic waves, the V-shaped protrusion 89 is selectively melted and the connecting member main body. Weld to 42. In the process of this melting, the surplus flows into the annular groove 88, so that it does not protrude to the outside. As a result, the filter member 51 is airtightly fixed between the connecting member 42 and the hollow needle 9.

【0017】

Returning to FIG. 5 again, the leg portions 41, 41 on both sides of the connecting member 42 have positioning dowels 90, 90 protruding from the inner intermediate portions thereof, and the overhanging portions 92, 92 on both sides of the head base 91. The holes 93 and 93 provided in the above are fitted into the positioning dowels 90 and 90, and both of them are integrally fixed by the screws 94 and 94.

【0018】

One end of the rising pipe 15 of the head unit 1 faces the head base 91 at a position corresponding to the above-mentioned ink through hole of the connecting member 2, and the rising pipe 15 and the first one on the connecting member 2 side. It is connected to the ink supply path 45 via an elastic joint 95. Reference numeral 97 in the drawing indicates a circuit board fixed to the upper surface of the head substrate.

【0019】

In this embodiment, when the ink tank 3 is set on the carriage 30 and the lever 33 is lowered, the hollow needle 9 is inserted into the communication pipe 43 of the ink tank 3. When the cap member 4 is attached to the head unit 1 and the pump 5 is operated in this state, the suction force of the pump 5 acts on the nozzle openings 27, 27, 27 .... via the cap member 4. This negative pressure acts on the ink tank 3 via the first ink supply path 45, the filter member 51, the second ink supply path 47, and the hollow needle 9, and the ink absorbed in the foam flows into these flow paths. .. When a predetermined time, for example, 0.1 to 1 second has elapsed, the pump is temporarily stopped to stop the suction operation. After a predetermined time, for example, 0.1 to 1 second, the pump 5 is operated again to suck out the ink from the foam 11.

【0020】

By intermittently driving the pump 5 in this way, the speed of the ink flowing through the ink supply path is suppressed to V1, for example, 1 mm / sec or less, and the flow rate is suppressed to an extremely low value of 0.01 cc / sec or less, resulting in rectification. The ink passes through the filter member 51, and foaming due to the mesh of the filter member 51 is prevented. Even if bubbles are generated at this time, the bubbles F (FIG. 9 (a)) pass through the filter member 51 while being crushed by the mesh (FIG. 9 (b)), and the fine bubbles f, f, It becomes f .... and flows into the head unit 1 from the ink supply path 47 ((c) in the figure).

【0021】

By intermittently executing such a suction operation a plurality of times, the flow path from the ink tank 3 to the head unit 1 is filled with ink while preventing foaming as much as possible. When the ink flows from the ink tank 3 to all the flow paths of the head unit 1 in this way, the pump 5 is continuously operated for 2 to 10 seconds, that is, the ink flow velocity is V2, specifically about 0.2 cc /. When suction is continued at a high flow velocity of seconds, the ink becomes a high-speed flow of speed V2 and flows from the tank 3 to the head unit 1, and adheres to the small bubbles flowing into the head unit 1 and the wall surface of the flow path. The air bubbles flow to the recording head 1 side by the high-speed flow, and are discharged to the cap member 4 from the nozzle opening 27. Even if the ink is filled by this high-speed flow, the flow path from the ink tank 3 to the nozzle opening is already filled with the ink, so that foaming does not occur.

【0022】

When the recording signal is output to the head unit 1 when the ink filling is completed, ink droplets are ejected to the recording paper in response to the recording signal by a well-known operation. The ink consumed by the head unit 1 is replenished from the tank 3 to the head unit via the ink supply path.

【0023】

Since the ink flow rate at the time of initial filling is set extremely small in this way, foaming in the ink flow path can be suppressed even when there is no liquid in the ink flow path. For this reason, it is possible to eliminate the need for the filling liquid that was conventionally filled in the ink flow path of the head unit at the time of shipment from the factory, and further, when an ink tank filled with ink that has not been degassed is attached. Also, no bubbles remain after filling.

【0024】

In the process of ink replenishment, the air bubbles flowing from the tank 3 into the hollow needle 9 move upward along the tapered wall surface 53a of the recess 53 constituting the filter chamber (FIG. 9 (d)) and extend in the horizontal direction. It does not flow into the ink supply path 45. In addition, small pieces of foam 11 and dust that have flowed out of the ink tank 3 are caught by the filter member 51 and do not flow into the head unit 1.

【0025】

The effect based on the intermittent drive of such a suction pump is maximized by setting the suction stop period to about 0.2 to 0.5 seconds.

【0026】

If the ink tank is replaced when all the ink in the tank 3 has been consumed by printing, the control device 6 fills the head unit 1 with ink from the tank in the first and second suction modes described above. ..

【0027】

[Effect of the invention]

As described above, according to the present invention, since the ink flow rate at the time of initial filling is set to be extremely small, foaming in the ink flow path can be suppressed even when there is no liquid in the ink flow path. The amount of ink required for discharging air bubbles can be minimized.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the ink supply system of the inkjet type recording apparatus to which the ink filling method of this invention is applied.

[Figure 2]

It is a figure which shows one Example of the head unit of the said apparatus.

[Fig. 3]

It is a perspective view which shows the state which was mounted on a carriage.

[Fig. 4]

It is sectional drawing which shows one Example of a head unit.

[Fig. 5]

It is an exploded perspective view which shows about the connecting part.

[Fig. 6]

It is sectional drawing which shows the filter member enlarged.

[Fig. 7]

FIGS. (I) to (III) are diagrams showing a manufacturing process of the filter member, respectively.

[Fig. 8]

It is a diagram which shows the operation of the pump by the ink filling method of this invention, and the flow rate of ink.

[Fig. 9]

FIGS. (A) to (D) are explanatory views showing the ink flow flowing through the filter and the state of air bubbles, respectively.

[Explanation of symbols]

1 head unit 2 Connecting member 3 ink tank 4 Cap member 5 suction pump 6 Control device 9 Hollow needle 26 Nozzle plate 51 Hollow needle 52, 53 Tapered through holes f, F bubbles