JP6341803B2 - Recovery method for liquid discharge head - Google Patents

Description

The present invention relates to a recovery method of the liquid discharge head.

  2. Description of the Related Art A liquid ejection apparatus that performs recording by ejecting liquid onto a recording medium while reciprocating a liquid ejection head is widely used as an image output apparatus. A general liquid ejection head includes a recording element substrate having an ejection port for ejecting liquid, and a support member having a liquid flow path for supplying liquid from a container holding the liquid to the recording element substrate. Yes. Then, energy is applied from a discharge element such as a heating element to the liquid supplied from the liquid container to the recording element substrate via the liquid flow path, whereby the liquid is discharged from the discharge port to the outside.

  In order to eject liquid from the liquid ejection head, the ejection port needs to be filled with liquid. However, if air exists in the flow path connected to the discharge port, the air hinders the flow of the liquid, the discharge port is not filled with the liquid, and stable discharge may not be performed. Even if the discharge port is filled with liquid, if a large amount of liquid exists around the discharge port on the discharge port surface, the discharge may be hindered and a fine image may not be formed.

  Therefore, a recovery operation is performed in which a negative pressure is generated by a pump or the like and suction is performed from the ejection port surface side of the recording element substrate to fill the liquid up to the ejection port, and further, sucking and cleaning excess liquid around the ejection port. It is common. As an example of such a recovery operation, there is a method of covering and sucking a part of the discharge port surface with a cap made of an elastic member, as shown in Patent Document 1. Further, as shown in Patent Document 2, there is also a method in which all the ejection openings provided in the recording element substrate are sucked in a state of being covered with a cap.

Japanese Patent Application No. 2007-253408 JP 2000-203060 A

  In the recovery method described in Patent Document 1, since the area that can be covered by the cap is smaller than the area of the entire area of the recording element substrate where the discharge ports are provided, only a part of the discharge ports is targeted. A suction operation is performed. Therefore, in order to suck all the discharge ports, it is necessary to repeatedly perform the suction operation while relatively moving the cap or the recording element substrate along the row direction in which the plurality of discharge ports are arranged, which is necessary for the recovery operation. Long time.

  On the other hand, in the recovery method described in Patent Document 2, since the recovery operation is completed by one suction operation without moving the cap or the recording element substrate, the required time can be shortened. However, when the cap covering all the discharge ports is released from the discharge port surface after the suction is completed, the liquid in the discharge port is drawn out because of the negative pressure inside the cap, and from the tip of the discharge port to the outside There is a possibility that the drawn liquid droplets remain and a liquid pool is generated on the discharge port surface.

  On the other hand, an absorbing member that absorbs liquid may be provided inside the cap so that no liquid pool remains on the discharge port surface. However, if such an absorbing member is present, it may become a resistance during suction, leading to a reduction in suction force, and air in the liquid flow path may not be sufficiently sucked in a short time. In addition, there may be a case where a liquid pool is prevented from being generated by providing a valve for breaking the residual negative pressure in the cap and releasing it to the atmospheric pressure after completion of the suction. However, by providing the valve, the number of parts becomes complicated.

An object of the present invention is to shorten the time required for the recovery operation, yet even without absorbing member and the valve puddle on the discharge port surface does not occur, it is to provide a recovery method of the liquid discharge head.

The method for recovering a liquid discharge head according to the present invention includes a step of covering a plurality of discharge ports of the liquid discharge head with a hollow cap, and a gas inside the discharge port covered with the cap by setting the inside of the cap to a negative pressure And aspirating the liquid. Furthermore, after the step of sucking, the method includes a step of sliding the cap relative to the liquid discharge head in a direction orthogonal to the row formed by the plurality of discharge ports. In the step of covering the plurality of ejection openings with the cap, the tip of the cap is brought into contact with the recording element substrate except for a part thereof, and a part of the cap is not in contact with the recording element substrate. In the step of relatively sliding the cap, the cap is slid with a portion not contacting the recording element substrate as a front end in the advancing direction.

  In the present invention, when the cap slides in a direction intersecting the row of ejection ports relative to the liquid ejection head, the cap can be quickly separated from the position covering the ejection ports with a short moving distance. In addition, since the inside of the cap is released to the atmosphere and the negative pressure is eliminated at a position away from the discharge port, the liquid in the discharge port is not sucked out at that time.

  Further, if a part of the cap is a portion that does not contact the recording element substrate (low wall portion), after the suction operation is stopped, air flows into the cap through the gap and the negative pressure atmosphere is immediately eliminated. Therefore, the liquid in the discharge port is not sucked out.

  According to the present invention, when the inside of the cap returns from the negative pressure atmosphere to the atmospheric pressure after the suction operation for recovery is finished, the liquid in the discharge port is not sucked out and adheres to the periphery of the discharge port. There is no accumulation of liquid on the outlet surface. Therefore, good liquid discharge can be performed.

It is the schematic which shows the principal part of the liquid discharge apparatus of this invention. FIG. 2 is a schematic diagram illustrating a recovery operation of the liquid ejection device illustrated in FIG. 1. FIG. 3 is a plan view illustrating a state in which the recording element substrate of the liquid ejection head is covered with a cap according to the first embodiment of the present invention. It is an expanded sectional view showing recovery operation of a 1st embodiment of the present invention. FIG. 6 is a plan view illustrating a state in which a recording element substrate of a liquid ejection head is covered with a cap according to a second embodiment of the present invention. It is an expanded sectional view showing recovery operation of a 2nd embodiment of the present invention. FIG. 10 is a plan view illustrating a state in which a recording element substrate of a liquid ejection head is covered with a cap according to a third embodiment of the present invention. It is an expanded sectional view showing recovery operation of a 3rd embodiment of the present invention.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings. The liquid discharge apparatus of the present invention includes a liquid discharge head 1 that can be reciprocated by a drive mechanism (not shown) and a recovery device 2 for recovering the liquid discharge head 1 (see FIG. 1). The liquid discharge head 1 includes a support member 9, a recording element substrate 6, and the like. The recording element substrate 6 is formed with an energy generating element (not shown) that generates energy used for discharging liquid and an ejection port 7. And a discharge port forming member to be formed. The recovery device 2 includes a recovery cap 3 that can face the liquid ejection head 1, a suction mechanism 5 such as a pump, and a pipe 4 that connects the recovery cap 3 and the suction mechanism 5. The recovery cap 3 has a hollow shape with a distal end opening, communicates with the pipe 4, and the inside is brought into a negative pressure state by the suction of the suction mechanism 5. The operation of the recovery device 2 will be briefly described. First, as shown in FIG. 2A, the recovery cap 3 is opposed to the ejection port 7 formed in the recording element substrate 6 of the liquid ejection head 1. Deploy. Then, as shown in FIG. 2B, the recovery cap 3 is brought into contact with the ejection port surface of the recording element substrate 6. Then, a suction force is applied from the recovery cap 3 to the recording element substrate 6 by the operation of the suction mechanism 5 such as a pump. When the suction operation is completed, as shown in FIG. 2C, the recovery cap 3 crosses the recording element substrate 6 with respect to the direction of the row formed by the plurality of ejection ports 7 (see FIGS. 3 and 4). Slide in the direction (preferably orthogonal).

  Specifically, the liquid ejection head 1 includes a recording element substrate 6 having ejection ports 7 and a support member 9 in which a liquid flow path 8 is formed. The discharge ports 7 are arranged in a plurality of parallel rows. FIG. 3 shows six discharge port rows, and for convenience, FIG. 4 shows three discharge port rows. A flexible printed circuit board 10 is disposed on the support member 9, and the recording element substrate 6 is exposed to the outside in a hole 10 a provided in the flexible printed circuit board 10.

  The tip of the recovery cap 3, that is, the portion in contact with the ejection element substrate 6 of the liquid ejection head 1 is a frame shape and shape that accommodates all ejection ports 7 of the recording element substrate 6, for example, a square, a circle, an ellipse, etc. It has a frame shape. A quadrangle as shown in FIG. 3 is particularly preferable because all the discharge ports 7 can be efficiently covered. As will be described later, the recovery cap 3 is preferably made of an elastic material in order to improve adhesion to the recording element substrate 6 when the ejection element substrate 6 is wiped and to prevent damage to the recording element substrate 6. For example, silicon rubber, nitrile rubber, fluorine rubber, etc. are more desirable from the viewpoint of ink wettability. However, it is not necessarily limited to these materials.

  The operation of the recovery device 2 will be described. In the recovery operation of the liquid discharge head 1, first, as shown in FIG. 2A, the recovery cap 3 is placed in the discharge port formation region of the recording element substrate 6 of the liquid discharge head 1. Arrange to face each other. Then, as shown in FIGS. 2B and 4A, the recovery cap 3 is brought into contact with the recording element substrate 6. At this time, as shown in FIG. 3, the recovery cap 3 covers all the ejection ports 7 of the recording element substrate 6. Then, the suction mechanism 5 such as a pump is operated to generate a negative pressure inside the recovery cap 3 through the pipe 4 and apply a suction force to the discharge port 7. Thereby, the gas (air) inside the discharge port 7 and the liquid flow path 8 is sucked into the recovery cap 3 together with the liquid. At this time, it is preferable that the liquid discharge head 1 is arranged in a posture in which the discharge port surface faces vertically upward because air in the liquid is more easily sucked. Finally, as shown in FIGS. 2C and 4B, the recovery cap 3 is slid on the ejection element substrate 6 in a direction orthogonal to the direction of the row formed by the plurality of ejection ports 7. . Thereby, the discharge port surface is wiped with the recovery cap 3, and the inside of the discharge port 7 and the recovery cap 3 is opened to the atmosphere.

  Thus, in this embodiment, after the recovery operation, the recovery cap 3 is slid in a direction orthogonal to the direction of the row formed by the plurality of discharge ports 7. Accordingly, the recovery cap 3 can be quickly moved away from the position covering all the discharge ports 7 with a short moving distance, and the discharge ports 7 can be opened to the atmosphere. Accordingly, the time required for the recovery operation is shortened. In particular, as shown in FIG. 3, when the recovery cap 3 is sized and shaped to cover all the discharge ports 7, all the discharge ports can be recovered in a single suction operation. It can be shortened.

  Further, if the recovery cap 3 is lifted in a direction perpendicular to the discharge port surface to be separated from the discharge port surface, the inside of the recovery cap 3 returns to the atmospheric pressure from the negative pressure before returning to the atmospheric pressure. The liquid was sucked out, and there was a possibility that a liquid pool was generated on the discharge port surface. However, in this embodiment, the recovery cap 3 is slid in a direction substantially parallel to the discharge port surface, and is separated from the discharge port 7 while maintaining the negative pressure atmosphere inside the recovery cap 3 to some extent. And since the inside of the recovery cap 3 is opened to the atmosphere and the negative pressure is eliminated at a position away from the discharge port 7, the liquid in the discharge port 7 is not sucked out at that time, and the discharge port surface It is difficult for a liquid pool to occur. In particular, when the side surface of the recording element substrate 6 is exposed without being sealed, as shown in FIG. 4B, a part of the sliding recovery cap 3 is outside the edge of the recording element substrate 6. As soon as it protrudes, air flows into the recovery cap 3 and the negative pressure is eliminated. Accordingly, the liquid in the discharge port 7 is not sucked out more than necessary, and the occurrence of a liquid pool around the discharge port 7 is suppressed. In addition, when the recovery cap 3 is slid, the tip portion wipes the wiping surface of the discharge port, so that liquid accumulation on the discharge port surface can be prevented.

  In the present embodiment, since the entire circumference of the tip of the recovery cap 3 is in close contact with the ejection port surface of the recording element substrate 6, the degree of vacuum tends to increase when the suction mechanism 5 is operated. For this reason, a good recovery operation can be easily performed, so that the manufacturing conditions of the recovery device 2 can be given a margin.

  In this embodiment, for example, in a liquid discharge head that has a large discharge port and discharges pigment ink, the degree of vacuum at the time of suction is increased to increase the amount of suction, thereby facilitating the discharge of air and the recovery time. There is an advantage that it can be shortened.

(Second Embodiment)
5 and 6 show a second embodiment of the present invention. In the present embodiment, a part of the distal end portion of the recovery cap 3 is a low wall portion 3a. Therefore, when the recovery cap 3 is in contact with the recording element substrate 6 and covers the discharge port 7, the low wall portion 3a does not contact the recording element substrate 6 as shown in FIG. Has occurred.

  When the suction mechanism 5 is operated to apply a suction force to the recovery cap 3 via the pipe 4 to suck out the liquid inside the discharge port 7, if the suction mechanism 5 generates a strong suction force to some extent, the gap The liquid can be sucked even if 11 is present. However, after the operation of the suction mechanism 5 stops, air flows in from the gap 11 and the negative pressure atmosphere is immediately eliminated. Accordingly, when the recovery cap 3 is moved away from the recording element substrate 6, the liquid inside the discharge port 7 is not sucked out. Accordingly, no liquid pool is generated on the discharge port surface.

  As shown in FIGS. 6B to 6C, also in this embodiment, the recovery cap 3 is slid in a direction orthogonal to the direction of the row formed by the plurality of discharge ports 7 after the recovery operation. As a result, the negative pressure atmosphere of the recovery cap 3 immediately disappears after suction as described above, and the same effect as that of the first embodiment can be obtained, and the occurrence of a liquid pool on the discharge port surface can be obtained. It can be suppressed more reliably.

  Further, in the present embodiment, as shown in FIG. 3, the tip portion extending along the discharge port array of the recovery cap 3 is the low wall portion 3a, and when the recovery cap 3 is slid, the low wall portion 3a is advanced. Slide as the front end of the direction. Therefore, as shown in FIG. 6C, when the member such as the flexible printed circuit board 10 is positioned on the recovery cap 3 side with respect to the recording element substrate 6, the slid recovery cap 3 collides with the member. It can be suppressed. Since the wall portion on the leading side of the recovery cap 3 is short, the area directly climbing on the member such as the flexible printed circuit board 10 is reduced when sliding, and the damage of the recovery cap 3 and the member can be suppressed by causing gentle interference. it can.

(Third embodiment)
7 and 8 show a third embodiment of the present invention. In the present embodiment, the outer wall surface 3 b on the front side in the traveling direction of the relative movement of the recovery cap 3 is inclined in a direction intersecting the acute angle 3 c with respect to the discharge port surface of the recording element substrate 6. Specifically, the outer wall surface 3 b is a surface on the front side in the traveling direction of the recovery cap 3 that slides relative to the liquid discharge head 1 in a direction intersecting the row formed by the plurality of discharge ports. The outer wall surface 3b is inclined in a direction intersecting the discharge port surface of the recording element substrate 6 at an acute angle 3c, and a part of the outer wall surface 3b is located above the flexible printed circuit board 10.

  As shown in FIGS. 8A to 8C, also in this embodiment, the suction mechanism 5 is operated to apply a suction force to the recovery cap 3 through the pipe 4, so that the liquid in the discharge port 7 is liquid. Suck out. Then, after the recovery operation, the recovery cap 3 is slid in a direction orthogonal to the direction of the row formed by the plurality of discharge ports 7. As a result, the same effects as those of the first embodiment described above can be obtained, and the occurrence of a liquid pool on the discharge port surface can be suppressed.

  Further, in the present embodiment, as shown in FIG. 8, the outer wall surface 3b of the recovery cap 3 is inclined in a direction intersecting the acute angle 3c with respect to the discharge port surface, and the outer wall surface 3b advances when the recovery cap 3 slides. Slide as the front end face of the direction. Therefore, as shown in FIG. 8C, when the member such as the flexible printed circuit board 10 is closer to the recovery cap 3 than the recording element substrate 6, the slid recovery cap 3 hits the member and the recovery cap It can suppress that 3 wears. Since the outer wall surface 3b on the front side of the recovery cap 3 is inclined in a direction that intersects at an acute angle with respect to the discharge port surface, the impact force directly received from the member such as the flexible printed circuit board 10 at the time of sliding is released in the wall surface direction. To interfere. As a result, damage received by the recovery cap 3 can be suppressed. At this time, the damage can be further suppressed as the outer wall surface 3b intersects the discharge port surface at an acute angle.

  In the present embodiment, since the entire circumference of the tip of the recovery cap 3 is in close contact with the discharge port surface of the recording element substrate 6, the degree of vacuum is easily increased when the suction mechanism 5 is operated, and the damage received by the recovery cap 3 due to the configuration described above. Therefore, a good recovery operation can be easily performed. Thereby, the freedom degree of material selection including the high hardness member which considered the durable improvement of the recovery cap 3 improves.

  In the above-described embodiments, the recovery cap 3 slides with respect to the liquid ejection head 1 after the recovery operation. However, the liquid ejection head 1 may slide with respect to the recovery cap. The mechanism for sliding the recovery cap 3 and the liquid discharge head 1 relatively may be any mechanism.

[Example 1]
A specific example in which the recovery operation is performed using the recovery device of the second embodiment shown in FIGS. In the liquid discharge head used in this example, a plurality of discharge ports 7 are arranged in a rectangular region (discharge port forming region) of the recording element substrate 6 whose longitudinal direction is 8.5 mm and whose lateral direction is 2.5 mm. Has been. The recovery cap 3 is made of silicon rubber, and its tip has a rectangular frame shape with an inner dimension of 10 mm × 3 mm, and can cover all the discharge ports 7. One side of this square is a low wall portion 3a that is shorter by 0.2 mm than the other pieces. The suction mechanism 5 is composed of a vacuum pump manufactured by ULVAC Kiko Co., Ltd.

  The recovery operation shown in FIGS. 2A to 2C and FIGS. 6A to 6C was performed in a state where liquid ink was previously injected into the liquid ejection head 1 having the above-described configuration. That is, first, as shown in FIG. 2A, the recovery cap 3 and the recording element substrate 6 of the liquid ejection head 1 are arranged facing each other. Next, as shown in FIGS. 2B and 6A, the recovery cap 3 is brought into contact with the ejection port surface of the recording element substrate 6, and the suction mechanism (vacuum pump) 5 is operated to reduce the suction pressure. The liquid and air inside the discharge port 7 and the liquid channel 8 were sucked by holding at 75 kPa and holding for 0.6 seconds. After the operation of the suction mechanism 5 was stopped, the recovery cap 3 was slid at a speed of 5 mm / sec in a direction perpendicular to the row of the discharge ports 7 as shown in FIGS. The time required for this series of recovery operations was 1.6 seconds. Then, when liquid is discharged using the liquid discharge head after this recovery operation, non-discharge due to the discharge port 7 not being filled with liquid, or excess liquid ink adheres around the discharge port 7 and remains. A good image was obtained without any distortion.

[Example 2]
Next, a specific example in which the recovery operation is performed using the recovery device of the first embodiment shown in FIGS. The same liquid ejection head 1 and suction mechanism 5 as those in Example 1 were used. Similarly to the first embodiment, the recovery cap 3 is made of silicon rubber, and the tip has a rectangular frame shape with an inner dimension of 10 mm × 3 mm, and can cover all the discharge ports 7. However, the recovery cap 3 of the present embodiment does not have the low wall portion 3a, and has the same length on all sides of the quadrangle, and simultaneously contacts the ejection port surface of the recording element substrate 6.

  With the liquid ink previously injected into the liquid discharge head 1, the recovery operation shown in FIGS. 2 (a) to 2 (c) and FIGS. 4 (a) to 4 (b) was performed. After the recovery cap 3 and the recording element substrate 6 face each other as shown in FIG. 2A, the recovery cap 3 is attached to the ejection port of the recording element substrate 6 as shown in FIGS. 2B and 4A. Touch the surface. The suction mechanism (vacuum pump) 5 was operated to set the suction pressure to −90 kPa and held for 0.5 seconds to suck the liquid and air inside the discharge port 7 and the liquid flow path 8. After the operation of the suction mechanism 5 was stopped, the recovery cap 3 was slid at a speed of 5 mm / sec in a direction perpendicular to the row of discharge ports. The time required for this recovery operation was 1.5 seconds, and when a liquid was discharged using the liquid discharge head after the recovery operation, a good image was obtained without any non-discharge or twist.

DESCRIPTION OF SYMBOLS 1 Liquid discharge head 2 Recovery apparatus 3 Recovery cap 3a Low wall part 3b Outer wall surface 5 Suction mechanism (vacuum pump)
6 Recording element substrate 7 Discharge port 11 Clearance

Claims (2)

Covering a plurality of ejection ports of the liquid ejection head with a hollow cap; and suctioning the gas and liquid inside the ejection port covered with the cap by setting the inside of the cap to a negative pressure; After the step of sucking, the step of sliding the cap relative to the liquid discharge head in a direction perpendicular to the row formed by the plurality of discharge ports,
In the step of covering the plurality of ejection openings with the cap, the tip of the cap is brought into contact with the recording element substrate except for a part thereof, and the recording is performed without bringing the part into contact with the recording element substrate. Leave a gap between the element substrate and
In the liquid sliding head recovery method, in the step of relatively sliding the cap, the cap is slid with the part not coming into contact with the recording element substrate as a front end portion in a traveling direction. Wherein in the step of covering a plurality of discharge ports in the cap, in the cap, covering all of the discharge port provided in the liquid ejection head, the recovery method for the liquid discharge head according to claim 1.

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