JPH082651B2 - Inkjet printer head recovery mechanism - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head recovery mechanism for an inkjet printer, and more particularly to a head recovery mechanism characterized by nozzle capping means.

[Prior Art] In an inkjet printer, it is necessary to protect the head during non-printing so that ink droplets can always be ejected from the nozzle during use.

Conventionally, the head recovery mechanism of this type of ink jet printer includes a cap module 32 for capping the head housing 18 at the head standby position 29 shown in FIG. In this case, as shown in FIG. 7, the nozzle at the tip of the head 30 and the ink discharge port 19 are covered with the cap 21 of the cap module, and the nozzle and the ink discharge port are exposed to the high humidity small chamber 24 in the cap. Was there.

[Problems to be Solved by the Invention] In the above-described head recovery mechanism of the inkjet printer, the nozzle is maintained in high humidity air, but there is a problem when it is not used for a long time. That is, since there is a limit to the degree of sealing between the head housing and the cap,
There is a drawback in that the ink in the nozzle does not thicken due to drying, and normal ink droplet ejection pressure cannot be obtained with normal ink droplet ejection pressure generated by the piezo effect or the like.

In addition, when an ink drop is ejected under a high load, air bubbles intrude into the head through the nozzle for some reason, or the air dissolved in the supplied ink precipitates in the head for some reason and creates bubbles. In this case, the air in the head ejects ink drops and absorbs the pressure, which may interfere with normal ink drop ejection.

Further, even at the time of printing, the nozzle is always exposed to the air flow, and especially when there is a plurality of nozzles, if there is a nozzle that does not perform ink droplet ejection for a long time, the viscosity of the ink at the tip of the nozzle increases, There is also a drawback that it cannot prevent solidification.

An object of the present invention is to cover a nozzle and an ink discharge port when not in use, and to suck ink in the nozzle and bubbles in the head housing as needed, thereby always enabling normal ink droplet ejection. An object is to provide a head recovery mechanism for an inkjet printer.

[Means for Solving the Problems] In order to achieve the above object, a head recovery mechanism of an ink jet printer of the present invention surrounds a tip of a nozzle, has an air inlet and an ink outlet, and has a head housing. Connected to the air chamber located at, the cap that covers the ink ejection port at the standby position when not printing, the air outlet provided on the cap, the exhaust part connected to the air inlet of the head housing, and the air outlet of the cap. And an air pump provided with the intake section.

According to a preferred embodiment, in the non-printing standby position, the cap is adapted to engage with the head housing by the rotational movement of the link arm with the side end of the carriage on which the head housing is mounted as the point of use. ing.
As a result, the ink ejection port is covered.

According to another embodiment, in the standby position when not printing,
The cap is adapted to engage the head housing by the action of a self-holding solenoid.

[Operation] At the head standby position during non-printing, the cap covers the ink ejection port to prevent the ink from thickening and solidifying at the nozzle tip due to drying. At that time, the air chamber is decompressed by an air pump to remove air bubbles in the head, and
Aspirate ink from long-term unused nozzle. As a result, proper ink ejection is always possible. On the other hand, when the head is used, the cap opens the ink ejection port, and normal ink ejection is possible.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings.

First, a general configuration of an inkjet head of an inkjet printer will be briefly described with reference to FIGS. 5 and 6. FIG. 5 is a schematic cross-sectional view of a head housing of an inkjet printer including a head that ejects ink droplets by an air flow, and FIG. 6 is a schematic plan view showing a carriage on which the head housing is mounted and printing paper. One or more inkjet heads 30 are mounted on the hud housing 18, and the tip of the head 30 projects into the air chamber 31 of the housing 18 and faces the nozzle at the tip of the head to discharge ink to the air chamber 31. Exit 19 is provided. The ink supply path 17 supplies ink to the head 30 and is an air inlet.
16 sends an air flow to the air chamber 31. Ink droplets 33 are ejected from the nozzle at the tip of the head 30 by the energy provided by a pump, an electric / mechanical energy conversion element or the like (not shown), and the ink droplets ride on the air flow from the air inflow port 16. The speed is increased, the ink is ejected from the ink ejection port 19 and reaches the print paper 25, and dots are formed on this paper.

The head housing 18 is fixed to a carriage 28 which is slidable on a guide shaft 27 (Fig. 6) as in the conventional case. The carriage 28 is driven at a predetermined speed by a motor (not shown).
Is moved, and at the same time, the printing paper 25 on the platen 26 is fed at a predetermined speed. Ink droplets 33 are ejected from the head 30 at an appropriate timing in synchronism with these to form desired characters, images, etc. on the printing paper 25.

Next, an embodiment of the head recovery mechanism of the inkjet printer of the present invention will be described with reference to FIGS. 1 and 2.
1 is a partial cross-sectional piping diagram of a head recovery mechanism according to an embodiment of the present invention when the carriage 28 is at the head standby position 29 of FIG. 6, and FIG. 2 shows the carriage 28 at the head standby position. FIG. 27 is a partial cross-sectional piping diagram of the head recovery mechanism when moved from 29. In FIG. 1, the head recovery mechanism is
The main components include a cap 21 for covering the tip of the head, an air pump 1 for sending air to the cap 21, and a three-port valve 10 for controlling the sending of air. Cap 21
Can be engaged with the head housing 18 so that the tip nozzle of the head 30 mounted in the head housing 18 and the ink ejection port 19 can be covered. The air intake portion of the air pump 1 is connected to the air outlet of the cap 21 through the air intake tube 6.
It leads to 22. The input port 14 of the three-port valve 10 communicates with the exhaust portion of the air pump 1 through the exhaust tube 7a, and the output port 13 communicates with the air inlet 16 of the head housing 18 through the exhaust tube 7b. There is. 3 port valve
10 further includes an outside air opening port 15. The 3-port valve 10 has an output port 13 and an outside air release port 15 inside.
Equipped with a valve plunger 11 that controls the opening and closing of the
The action of 12 causes the valve plunger 11 to move to the outside air release port 15
Is applied, that is, to the left in FIG.

A link arm 3 is provided as a means for engaging the cap 21 with the head howling 18 and for separating the cap 21 from the head housing 18. This link arm 3 can rotate around the fixed shaft 4 and the cap 21
It has a first arm portion 3a pivotally attached to the second arm portion 3b, a second arm portion 3b capable of contacting the carriage 28, and a third arm portion 3c engaged with the protruding end of the valve plunger 11. The coil spring 34 applies a force to the link arm 3 in the direction of separating the cap 21 from the head housing 18 (the direction of the arrow in FIG. 1).

When the carriage 28 is in the head standby position (the state shown in FIG. 1), the side end 28a of the carriage 28 presses the link arm portion 3b and resists the force of the spring 34 to move the link arm 3 counterclockwise. Rotate. This allows the cap 21
The seal rubber 20 at the tip of is engaged with the head housing 18, and the ink discharge port 19 is covered with a cap. At the same time,
The arm portion 3c moves the valve plunger 11 to the right against the force of the spring 12, opens the outside air release port 15 and closes the output port 13, and disconnects the communication between the air chamber 31 of the head housing 18 and the air pump 1. . Then, the air pump is operated to suck the air in the air chamber 31 of the head housing 18 through the suction tube 6, the air outlet 22, the small chamber 24 in the cap 21, and the ink discharge port 19, and decompress this air chamber. To do. As a result, the ink is sucked from the tip nozzle of the head 30, and the thickened ink and bubbles are discharged from the head 30. The discharged ink is absorbed by the absorbing material 23 in the cap small chamber 24.
It is sucked up by the air and increases the relative humidity in the small chamber 24 during capping. Therefore, the wetting effect near the tip nozzle of the inkjet head 30 is improved, and it is possible to suppress the drying, thickening, and solidification of the ink. On the other hand, since the outside air release port 15 of the three-port valve 10 is open, the exhaust air from the air pump 1 is discharged from the outside air release port 15 into the atmosphere through the exhaust tube 7a and the input port 14.

When the carriage 28 moves away from the standby position 29 along the guide shaft 27 due to the printing operation of the printer (the state shown in FIG. 2), the action of the coil spring 34 causes the link arm 3 to rotate clockwise and the cap 21 to move to the head housing.
Pull away from 18. On the other hand, the valve plunger 11 of the three-port valve 10 moves leftward by the action of the spring 12 to close the outside air opening port 15 and open the output port 13. Therefore, the exhaust air flow from the air pump 1 is exhausted by the exhaust tube 7
After passing through a, the input port 14, the output port 13 and the exhaust tube 7b to the air inlet 16, the air is supplied as an air flow into the air chamber 3 of the head housing 18. The ink droplets ejected from the head 30 ride on this air flow to accelerate and form dots on the printing paper 25 supported by the platen 26 (see FIG. 6).

3 and 4 show another embodiment of the head recovery mechanism of the inkjet printer of the present invention. This embodiment is substantially different from the embodiments of FIGS. 1 and 2 in that
How to operate the link arm and the existence of the drainage cartridge.

In this embodiment, in the middle of the intake tube 6 that connects the air outlet 22 of the cap 21 and the intake portion of the air pump 1,
A replaceable drainage cartridge 35 is provided. The cartridge 35 is detachably accommodated in the drain trap 8 and has an absorption felt 9 therein. During capping (state of FIG. 3), the ink sucked by the air pump 1 falls onto the absorbent 23 in the cap small chamber 24, but the ink overflowing from the absorbent 23 is sucked in through the air outlet 22. It is sucked into the tube 6. This ink is collected by the drainage cartridge 35 in the drainage trap 8. Therefore, the ink sucked from the head 30 does not overflow from the cap 21, and the absorbent 23 holds a constant amount of liquid. This increases the relative humidity in the small chamber 24 during capping, improves the wetting effect near the tip nozzle of the head 30, and prevents the ink from drying, thickening, and solidifying.

Furthermore, this embodiment is characterized by the method of operating the link arm 3. The link arm 3 comprises an arm portion 3d pivotally attached to the cap 21 and an arm portion 3e pivotally attached to the fixed shaft 4b, these arm portions 3d, 3e being pivotally attached to the pin 5 of the self-holding solenoid 2. There is. Arm part
Similar to the arm portion 3c of the previous embodiment, 3e engages with the protruding end of the valve plunger 11 and controls the movement of this valve plunger 11.

At the time of capping (state shown in FIG. 3), the solenoid 2 is in the de-energized state, and the coil spring 34 moves to the pin 5
At this position, the arm portions 3d and 3e are pulled to the left. As a result, the seal rubber 20 of the cap 21 is engaged with the head housing 18 to cover the ink ejection port 19, and the outside air opening port 15 of the three-port valve 10 is opened and the output port 13 is closed. The operation by the air pump 1 in this case is similar to that of the previous embodiment.

When the ink discharge port 19 is opened for the printing operation by the printer, as shown in FIG. 4, the solenoid 2 is urged and the pin 5 is pulled rightward against the force of the spring 34 so that the arm portion is released. Rotate 3d and 3e counterclockwise and clockwise, respectively. As a result, the cap 21 separates from the head housing 18 to open the ink ejection port 19, and the valve plunger 11 closes the outside air opening port 15 and opens the output port 13 to connect the air pump 1 to the air chamber 31. The operation by the air pump 1 in this case is similar to that of the previous embodiment.

Therefore, also in the embodiment shown in FIGS. 3 and 4, the ink is prevented from being dried, thickened and solidified at the time of capping, and at the time of printing, the ink droplets are put on the air flow from the air pump to accelerate the ink so that the ink is printed on the paper. Dots can be formed.

[Effect of the Invention] As described above, according to the present invention, the intake portion of the air pump that generates the air flow for increasing the proper flight speed of the ink is connected to the cap, and the head during capping is regularly or as needed. By sucking the ink by the pump operation from the tip of the nozzle, it is possible to prevent the ink from being dried, thickened, and solidified, and at the same time, it is possible to discharge the bubbles in the nozzle and always stably eject the ink droplets.

[Brief description of drawings]

FIG. 1 is a partial sectional piping diagram of a head recovery mechanism of an inkjet printer according to an embodiment of the present invention, showing a state during capping, and FIG. 2 is a partial sectional piping diagram similar to FIG. However, FIG. 3 is a diagram showing a state when the ink ejection port is opened, FIG. 3 is a partial sectional piping diagram of a head recovery mechanism according to another embodiment of the present invention, and a diagram showing a state at the time of capping, and FIG. FIG. 5 is a partial sectional piping diagram similar to FIG. 3, but showing the state when the ink discharge port is opened. FIG. 5 is a schematic sectional view of a head housing of an inkjet printer related to the present invention, and FIG. FIG. 7 is a partial plan view of an ink jet printer showing a head housing mounted on a carriage and printing paper, and FIG. 7 is a schematic sectional view of a conventional head recovery mechanism. 1 ... Air pump, 3 ... Link arm, 10 ... 3-port valve, 16 ... Air inlet, 18 ... Head housing, 19 Ink outlet, 21 ... Cap, 22 ... Air outlet, 25 ... Printing Paper 28 …… Carriage, 29 …… Standby position 30 …… Head, 31 …… Air chamber 33 …… Ink droplets

Claims (1)

[Claims] 1. A head recovery mechanism of an ink jet printer, wherein ink droplets are ejected from the tips of minute nozzles arranged in a head housing to form dots on a sheet, and a set of dots produces characters, images, and the like. An air chamber that surrounds the tip of the minute nozzle and has an air inlet and an ink outlet, is provided in the head housing, a cap that covers the ink outlet at a standby position during non-printing, and a cap An air pump having an air outlet provided, an exhaust unit connected to the air inlet of the air chamber, and an intake unit connected to the air outlet of the cap; and an exhaust of the air pump connected to the exhaust unit. A three-port valve that selects whether the air is exhausted to the outside or is discarded at the air inlet of the air chamber, and a standby position when the head housing is not printing Or head recovery mechanism of an ink jet printer according to the one position during printing having a mechanism for controlling the selection of the exhaust of the 3-port valve