JP3417449B2 - Ink jet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an ink jet recording head which moves in the width direction of a recording sheet, and uses a plurality of color inks in accordance with print data. The present invention relates to a capping device of an ink jet printer that prints a color image by ejecting it on a recording sheet, and an ink jet printer that mounts a plurality of ink jet recording heads on the same carriage and enables printing at a high density. 2. Description of the Related Art A recording apparatus equipped with an ink jet recording head has relatively low noise at the time of printing and can form small dots at a high density. Therefore, it is used for many printings including color printing. I have. In such a recording apparatus, the ink pressurized in the pressure generating chamber is ejected from the nozzles as ink droplets onto the recording paper to form dots, so that in order to improve print quality, bleeding on the recording paper is prevented. It is necessary to reduce the proportion of the ink solvent as much as possible, or to use a material that easily evaporates. As a result, the ink solvent evaporates from the nozzle openings during printing and the viscosity of the ink rises. Even if the nozzle surface is sealed with a cap at rest, the viscosity of the ink at the nozzle openings also rises. In this case, ink ejection is hindered. In order to solve such a problem, for example, Japanese Patent Application Laid-Open
As disclosed in Japanese Patent No. -40342, a printing head is moved to a non-printing area after a predetermined time elapses during printing, and the nozzle plate is sealed with a capping means provided in this area to suction pump. Ink is forced to be ejected from all the nozzle openings by applying a negative pressure from the nozzle. At the time of such forced ink ejection, an ink absorbing plate made of a porous material is housed at the bottom of the capping means in order to prevent the ink from splashing from the capping means. On the other hand, at the time when the forced ejection of ink is completed, a large amount of ink remains on the ink absorbing plate, and it is necessary to eliminate this. However, since the opening area of the ink suction port communicating with the suction pump is extremely small compared to the area of the ink absorbing material, it is necessary to use the capillary force of the ink absorber to draw the ink at the corners to the ink suction port. Above, with the recording head sealed, the air permeability is reduced to some extent by a valve or the like to open to the atmosphere, suction is further performed by a suction pump, and the negative pressure on the nozzle opening is reduced as much as possible. An operation for sucking out the ink remaining on the absorbing plate is required. At this time, if the air flowing into the capping means directly touches the nozzle openings, the nozzle openings are dried, so that the air flows through the ink absorbing plate. Have been. For this reason, the ink of the ink absorbing plate is bubbled by the air flow, and the bubble adheres to the nozzle plate and changes the affinity of the ink near the nozzle opening, or destroys the meniscus of the nozzle opening, thereby deteriorating the printing quality. There is a problem. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to prevent bubbles generated when discharging waste ink stored in capping means from reaching a nozzle opening. It is an object of the present invention to provide an ink jet recording apparatus capable of preventing the occurrence of the image. In order to solve such a problem, the present invention forms a plurality of nozzle openings in a row and forms a crater portion surrounding the nozzle openings in the same row. An ink jet recording apparatus comprising: an ink jet recording head having a nozzle plate formed therein; and capping means for sealing a nozzle opening of the nozzle plate, wherein the nozzle plate has a common recess around the same row of the nozzle openings. A crater body that surrounds to form a row of nozzle openings on both sides of the row of nozzle openings from the crater body .
A crater portion formed by branches arranged in
Further, the capping means is configured to accommodate the ink absorbing plate facing the crater main body portion and facing the outer peripheral region of the nozzle opening, and the ink absorbing plate facing the branch on one side. It comprises a concave portion for ink absorption provided with an ink suction port communicating therewith, and a concave portion for air introduction communicating with the atmosphere via a valve opposed to the branch on the other side . When the ink discharged from the recording head to the capping means is sucked to the outside, the atmosphere is taken in as a flow from the nozzle plate toward the bottom of the capping means, and bubbles generated in the ink absorbing plate are capped. Pushing back to the bottom of the means prevents it from reaching the nozzle plate. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; FIG. 1 shows an outline of the periphery of a printing mechanism of an ink jet recording apparatus according to the present invention. In the drawing, reference numeral 1 denotes a carriage, which is supported by a guide member 2 and a pulse motor 4 via a timing belt 3. And is configured to be able to reciprocate in parallel with the platen 5. The carriage 1 is provided with a recording head 10 having a nozzle opening 11 for discharging ink, and an ink cartridge 6 for supplying ink to the recording head 10 is detachably mounted. Reference numeral 20 in the figure denotes a capping device which is a feature of the present invention, and is disposed outside the printing area. When the recording head 10 moves to a predetermined position, recording is performed in conjunction with the movement of the carriage 1. The head 10 is configured to move to the nozzle plate side so that a cap member 21 described later elastically contacts the nozzle plate. In the recording head 10, the gap between the nozzle plate 12 and the recording paper is set to be extremely small because it is necessary to precisely land a minute ink droplet at a predetermined position. As a result, there is a possibility that the water-repellent treatment layer provided around this may be worn. [0014] To avoid such a problem, in the region had septum from the nozzle openings 11 about 100 to 150μm as shown in FIG. 2, to form the metal layer 13 having a thickness of 5 to 30 [mu] m, the nozzles A crater body 14 is provided so as to surround the opening 11, the crater body 14 prevents the recording paper from contacting the water-repellent layer near the nozzle opening, and cooperates with the above-described capping means 20 to form the nozzle opening. In order to form an ink discharge path when ink is forcibly discharged from the printer 11, branch paths 15 and 15 ′ extending to both sides are formed so as to communicate with the main body 14. Further, in the vicinity of the capping device 20 in the non-printing area facing the moving path of the recording head 10, a cleaning member 7 constituted by bonding a felt plate and a rubber plate is arranged. In addition, the code | symbol 8 in a figure shows a suction pump. FIG. 3 shows an embodiment of the cap member 21 accommodated in the above-mentioned capping device. The cap member 21 is provided with a nozzle opening 11 and a sealing member elastically in contact with the outside of the nozzle opening 11 at a predetermined interval. Stop areas 22, 23;
Between the sealing regions 22 and 23 and the recesses 24 and 24 for discharging ink formed in a region facing the branch 15 outside the nozzle plate 12 and the branch 15 ′ inside the nozzle plate 12. An air introduction recess 25 formed in the opposed region is formed on an elastic member such as rubber. An ink suction port 26 communicating with the suction pump 8 is formed on the bottom surface of the ink discharge recesses 24, 24,
An ink absorbing plate 28 made of a thin plate of a porous material is accommodated on the entire bottom surface so as to cover this. At the bottom of the concave portion 25 for introducing air, an air inlet 27 communicating with the atmosphere via a valve (not shown) is provided. In this embodiment, during the rest period,
As shown in (a), the sealing region 22 of the cap member 21
Elastically contacts the outer periphery of the nozzle opening 11 to seal the nozzle opening 11. In this state, the cap member 21 is prevented from directly contacting the nozzle opening 11 by the crater body 14 around the nozzle opening, while the nozzle opening 1 is prevented.
Numeral 1 is prevented from drying by the solvent vapor of the ink slightly remaining in the ink absorbing plate 28 in communication with the concave portions 24, 24 via the branch path 14, and does not cause clogging. On the other hand, when printing is resumed after a pause or when printing is continued for a predetermined time, the suction pump 8 is operated to apply a negative pressure to the cap member 21 in the above-described capping state. Then, a negative pressure acts on the crater main body 14 through the branch passage 15 and the nozzle opening 11
, The ink is forcibly discharged into the concave portions 24, 24. By discharging the ink, the film and the like formed in the nozzle opening 11 due to drying or the like are removed to the concave portions 24 and 24 together with the thickened ink near the nozzle opening, and the ink discharging ability of the nozzle opening 11 is restored. The ink discharged from the nozzle opening 11 flows into the concave portion 24 via the branch path 14, is absorbed by the ink absorbing plate 28 accommodated therein, and is partially discharged from the ink suction port 26 to the outside. You. When the suction time necessary for restoring the ink discharge capability has elapsed, the valve (not shown) is opened to open the recess 2.
5 is communicated to the atmosphere, and the suction capacity of the suction pump 8 is lowered to continue suction, the ink absorbed by the ink absorbing plate 28 moves to the ink suction port 26 side by the capillary force of the ink absorbing plate 28. To the waste ink tank by the negative pressure of the pump. At this time, the air from the air inlet 27 is
As shown by the arrow B in FIG. 4 (b), the flow is restricted by the branches 15 'formed in the crater main body 14, and flows through a widely dispersed space, so that the flow is as low as possible. Since the flow is directed from the nozzle opening side to the bottom of the cap member 21 without destruction of the meniscus of the nozzle opening, foaming is minimized as compared with the case where the ink flows into the ink absorbing plate intensively from a small number of openings. Even if ink bubbles are generated in the ink absorbing plate 28, the ink flow is impeded by the airflow from the nozzle opening side and cannot reach the nozzle opening 11. In the above-described embodiment, the concave portion for discharging ink is formed on the side, and the concave portion for introducing air is formed on the center side. Obviously, the same effect is obtained even if a concave portion for discharging ink is formed on the side. As described above, according to the present invention, when the ink discharged from the recording head to the capping means is sucked to the outside, the air flows from the nozzle plate side to the bottom of the capping means as air. It is possible to prevent bubbles generated in the ink absorbing plate from being pushed back to the bottom of the capping means and reaching the nozzle plate. Further, since the cap means is in contact with the vicinity of the nozzle opening, drying of the nozzle opening can be more reliably prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a structure around a printing mechanism of an ink jet recording apparatus according to the present invention. FIGS. 2A and 2B are a front view and a cross-sectional view taken along line AA, respectively, showing an embodiment of a nozzle plate constituting a recording head according to the present invention. FIGS. 3A and 3B are a front view and a cross-sectional view, respectively, showing an embodiment of a cap member used in a capping device. FIGS. 4A and 4B are diagrams showing states of forced ejection of a recording head by the capping device and removal of ink from an ink absorbing plate, respectively. DESCRIPTION OF SYMBOLS 10 Recording head 11 Nozzle opening row 12 Nozzle plate 14 Crater body 15, 15 'Branch 20 Capping means 21 Cap members 22, 23 Sealing area 24 Ink discharge recess 25 Air introduction recess 26 Ink suction port 27 Atmospheric introduction port 28 Ink absorption plate

Claims (1)

(1) An ink jet recording head comprising: a nozzle plate having a plurality of nozzle openings formed in a row and a crater portion surrounding the nozzle openings in the same row; In an ink jet recording apparatus comprising: a capping means for sealing a nozzle opening of a nozzle plate, wherein the nozzle plate is provided around a same row of the nozzle openings.
A crater body that surrounds to form a common recess , and from the crater body to both sides of the row of nozzle openings
A crater portion formed by branch lines arranged so as to intersect the row of the nozzle openings, and wherein the capping means is opposed to the crater body portion and is in contact with an outer peripheral region of the nozzle openings. A stop area, an ink absorbing plate which accommodates an ink absorbing plate facing the branch on one side and has an ink suction port communicating with a pump, and the branch on the other side. An ink jet recording apparatus, comprising: a recess for introducing air to the atmosphere via a valve, facing the path.