JPH07314733A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To remove remaining ink in a recording head without damaging sealing properties of the recording head and a cap. CONSTITUTION:A recessed section of a cap 30 is fitted in a nozzle section 15 of a recording head 10 on a non-recording position to shut off atmosphere. The roughness of an inner face wall of the cap 30 is increased as the wall gets closer to an ink outflow opening to accelerate capillarity and quicken the flow of ink sucked by a suction pump 40 down into the ink outflow opening direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and particularly to sucking a recording liquid (ink) adhering to the surface of a recording head after discharging the recording liquid to prevent the recording head from maintaining good ejection property and drying. The present invention relates to an inkjet recording apparatus provided with a recovery device.

[0002]

2. Description of the Related Art Conventionally, an ink jet recording apparatus is configured to eject an ink droplet from an ink ejection port of a recording head according to image information and record an image on a recording medium. However, during the non-printing period, the water content of the ink liquid evaporates from the ejection port, the amount of ink clay increases, and the ink adheres to the ejection port surface and the recording density changes. In order to prevent these inconveniences, normally when not recording, the normal device abuts a cap member made of an elastic material around the nozzle portion of the ink ejection surface of the recording head to seal the ink ejection port and shut it off from the outside air. In addition, removal of dust and dirt adhering to the ink discharge port, thickened ink, etc., and removal of bubbles generated inside the nozzle by suctioning through the tube with the suction pump with the cap in contact Equipped with means.

However, after performing the suction operation by the recovery means, the ink sucked from the discharge port remains on the contact portion of the cap which contacts the head surface, and after the cap is opened and closed, the residual ink adheres to the recording head surface. As a result, there is a problem in that the ejection failure is caused by clogging of the ejection port, or when a plurality of inks of different colors are used, color mixture due to residual ink occurs. As a means for solving the above problem, as shown in FIGS. 8 and 9, a contact surface 83 of the cap 80 for contacting the recording head is provided with a processing surface coated with a fluororesin so that the contact with the recording head is achieved. A method of imparting water repellency to a surface is disclosed in Japanese Patent Laid-Open No. 4-219250.

[0004]

However, the surface hardness of the contact portion of the cap with the recording head by this means becomes high due to the coating treatment. As a result, the coated portion was cracked or peeled off, which adversely affected the sealing property between the recording head and the cap. In addition, this method causes problems such as cost increase due to the coating process. Therefore, an object of the present invention is to eliminate residual ink in the recording head without affecting the sealing property between the recording head and the cap.

[0005]

In order to solve the above problems, an ink jet recording apparatus of the present invention is a cap member for fitting a recording head for ejecting an ink droplet from an ink ejection port of a nozzle portion in accordance with image information. The inner wall of the recess of
The surface roughness is gradually increased (the difference in surface roughness is 5 μmRZ or more) from the upper surface of the cap member toward the ink outflow hole for discharging the ink out of the cap.

[0006]

By the above means, the ink sucked from the nozzle portion of the recording head flows down by the capillary phenomenon in accordance with the roughness of the inner wall surface of the cap member, and flows into the ink outflow hole without remaining on the surface, and inside the cap member. Will not remain in

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall view of a recovery device in an inkjet recording device. The recording head 10 is in the standby (recovery) position and is in the capping state. The cap 30 is supported by the cap holder-35,
The recovery device 20 of the inkjet recording device is arranged at a predetermined position. The cap 30 is made of an elastic body such as rubber. The cap 30 is a holder 3 which is driven by a cam 25 to move up and down.
5, the nozzle portion 15 of the recording head 10 at the non-printing (recording) position is fitted, and the periphery of the nozzle portion 15 is covered to form a hermetically sealed state. The cap 30 is connected to the suction pump 40 via a connecting pipe 45. The suction pump 40 is driven by suction to generate a negative pressure in the cap through the connecting pipe 45, and sucks ink, dust, bubbles in the nozzle or the like from the nozzle portion 15. A cleaning blade 50 is arranged adjacent to the cap 30. The cleaning blade 50 is made of an elastic material, is supported by a blade holder 55, is erected, and is moved up and down to move the blade 50 to a position where it can contact the nozzle surface 15. Then, as the recording head 10 moves, the cleaning blade 50 wipes and cleans the ink remaining on the nozzle 15 surface of the recording head 10 after suction.

2 to 4 show a cap according to the present invention, FIG. 2 is a plan view, FIG. 3 is a sectional view taken along the line AA of FIG. 2, and FIG. 4 is a sectional view taken along the line BB of FIG. The cap 30 is made of an elastic material such as butyl chloride rubber and has a recess 31 for accommodating the nozzle portion 15 of the recording head 10. In the center of the recess 31, an ink outflow connecting a connecting pipe 45 connecting to the suction pump 40 is provided. The hole 33 is drilled. The peripheral edge of the concave portion 31 is projected to form a protruding portion 35, and when it is fitted into the nozzle portion 15 of the recording head 10, the recording head surface is brought into pressure contact. The cap 30 has a rough surface by forming fine irregularities on the inner wall surface 313 of the recess 31. In the formation state of the unevenness, a small roughness surface R is formed as a small unevenness surface (low roughness) near the protrusion 35. Then, the unevenness is gradually increased toward the ink outflow hole 33 (roughness) to form a large roughness range T.
Is formed. The cap 30 is formed by die molding, but by providing an uneven surface on the recess forming wall surface of the die,
An uneven surface having a desired roughness (size, density) can be formed.

When the cap 30 thus constructed is fitted into the nozzle portion 15 of the recording head 10 and the suction pump 40 is operated, the inside of the cap 30 becomes a negative pressure, and the ink remaining in the nozzle is sucked and the cap 30 is discharged. Is discharged inside. The ink in the cap 30 flows down and the ink outflow holes 3
3 is discharged to the connecting pipe 45. At this time, cap 3
The ink in 0 flows through the concave surface from the small roughness range R of the wall surface to the large roughness range T due to the capillary phenomenon. Then, they gather around the ink outlet 33 located on the surface facing the nozzle surface 15 of the recording head 10, and are removed from the inside of the cap 30 by the suction operation of the suction pump 40.

Next, the state of movement of the ink due to the difference in the roughness (roughness) of the wall surface from the protrusion 35 of the cap 30 toward the ink outflow hole 33 was observed. The result is shown in the graph of FIG. In this graph, the horizontal axis represents the magnitude of the difference in wall surface roughness, and the vertical axis represents the residual ink amount. As shown in this graph, the ink remaining on the wall surface of the cap has a large amount of ink remaining on the inner surface of the cap 40 when the difference in roughness is small, and when the difference in roughness is large, the cap 4
0, the amount of ink remaining on the inner surface has decreased. According to this experiment, it was found that the difference in surface roughness is preferably 5 μmRZ or more.

Next, the relationship between the surface roughness of the cap 30 and the sealing property of the recording head 10 was tested. The result is shown in the graph of FIG. In this graph, the horizontal axis represents the degree of roughness of the wall surface of the cap, and the vertical axis represents the quality of sealing with the nozzle surface 15. According to this graph, the smaller the roughness (denseness) of the portion of the cap 30 that is in contact with the nozzle surface 15 of the recording head 10, the better the sealing performance, and the higher the roughness, the worse the sealing performance. However, it was found from this experiment that there is no particular problem if the thickness is 100 μmRZ or less. That is, the maximum unevenness for forming the rough surface on the inner wall surface of the concave surface of the cap 30 according to the present invention is 100 μmRZ at the maximum, and the difference from the minimum unevenness is 5 μmRZ or more, whereby the ink is smoothly discharged.

As described above, in the ink jet recording apparatus according to the present invention, the ink 14 does not remain on the surface of the cap 3 after the ink is sucked and the like, and the ink 14 is not redeposited on the recording head surface 11 and the problem of clogging is eliminated.

[0013]

In the ink jet recording apparatus of the present invention, when the recording is not performed, the recording head at the recovery position is covered with the cap having the contact surface with the difference in roughness, so that the ink sucked by the suction pump is capillarized. Leaves the recording head surface,
Since the ink flows down in the direction of the ink outflow hole, the ink does not remain on the cap surface. Further, since the upper surface of the cap has a low roughness, the sealing performance to the recording head surface is not impaired.

[Brief description of drawings]

FIG. 1 is an overall view of a recovery device of an inkjet recording device.

FIG. 2 is a top view of the cap member of the present invention.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along line BB in FIG.

FIG. 5 is a partially enlarged view of the cap member.

FIG. 6 is a graph showing the relationship between the difference in surface roughness of the cap member and the residual ink amount.

FIG. 7 is a graph showing the relationship between the surface roughness of the cap member and the hermeticity.

FIG. 8 is an explanatory view of a conventional cap.

9 is a top view of FIG. 8. FIG.

[Explanation of symbols]

10 recording heads, 15 nozzles, 20 recovery device, 30 caps, 31 recesses, 33 ink outflow holes.

Claims (2)

[Claims] 1. A recording head for recording an image on a recording medium by ejecting ink droplets from an ink ejection port of a nozzle portion according to image information, and a nozzle portion of the recording head is shielded from the outside air during non-recording. In a recording apparatus having a cap member made of an elastic body, the cap member has a recess for fitting the recording head and an ink outflow hole for discharging the ink out of the cap, and the inner wall surface of the recess of the cap member is from the upper surface of the cap member. An inkjet recording apparatus in which the surface roughness gradually increases toward the ink outflow hole. 2. The ink jet recording apparatus according to claim 1, wherein the difference in surface roughness of the inner wall surface of the cap member is 5 μmRZ or more.