JP2007331255A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an image quality, at an end of a recording medium, from being degraded because a landing position of a satellite or an ink mist is shifted in an outside direction of the recording medium owing to suction of a borderless groove arranged for borderless recording. <P>SOLUTION: The recorder is characteristically provided with an air inflow groove extending to a downstream side in the recording medium carrying direction of a platen from the borderless groove so that air is introduced into the inside of the borderless groove. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus provided with a suction platen.

  Conventionally, in an ink jet recording apparatus, the distance between the surface of the recording medium and the recording head must be kept constant in order to perform stable recording. Therefore, it is necessary to eliminate as much as possible the floating of the recording medium due to the influence of wrinkles and wavy deformation (hereinafter referred to as cockling) generated when ink is ejected onto the recording medium. In addition, even for a recording medium that has been curled due to moisture or the like, it is necessary to prevent paper floating from the platen toward the recording head.

  This is because when the recording medium is lifted, a recording head, a carriage that is mounted with the recording head and moves in the main scanning direction at the time of image formation, a guide provided in the vicinity of the recording unit, etc. come into contact with the floating part of the recording medium. Because it is rubbed. If the recording head or carriage is rubbed with the recording medium, the recording surface may be damaged or soiled, resulting in a reduction in image quality. Furthermore, there is a possibility that the discharge port surface (discharge port arrangement surface) of the recording head may be damaged.

Therefore, a configuration has been proposed in which a suction platen is provided at a position facing the recording head to suppress curling and cockling of the recording medium. The suction platen is equipped with a number of suction holes on the recording medium contact surface of the suction box formed in a box shape,
This is a platen that sucks and holds the recording medium on the recording medium contact surface with a negative pressure inside the suction box. The negative pressure is generated by exhausting from the inside of the suction box with a fan (see, for example, Patent Document 1 and Patent Document 2).

  On the other hand, when performing borderless recording without leaving margins at the front and rear ends in the recording medium conveyance direction, a long image is formed on the roll-shaped recording medium in the recording medium conveyance direction, and the front and back images are formed with a cutter. Cut a part. When performing borderless recording without leaving a margin at the end in the width direction, a configuration has been proposed in which recording is performed in an area wider than the recording medium width.

  In this case, the ink ejected to the outside of the recording medium width is received by the concave portion opened on the recording medium conveyance surface of the platen that holds the recording medium at the image forming position. Some of the recesses are provided with an ink absorbing material for absorbing the received ink. Alternatively, a borderless recording is made possible by forming an inclined surface in the concave portion that extends downward from the recording medium holding surface and disposing an ink receiver having an opening for flowing ink to the waste ink storage area (for example, (See Patent Document 3).

  Hereinafter, a conventional suction platen will be described with reference to the drawings. FIG. 7 is a top view showing a conventional suction platen as seen from the top surface of the main body, and FIG. 8 is an enlarged view showing an enlarged borderless groove on the end of the recording medium in FIG.

  7 and 8, the suction platen 28 that holds the back surface of the recording medium includes a suction groove 28a that is formed in a concave shape with respect to the recording medium holding surface and extends in the sub-scanning direction. A suction hole 28a1 is provided in the suction groove 28a. The width y2 of the suction groove 28a in the sub-scanning direction is wider than the nozzle width y1 of the recording head 41 that discharges ink onto the recording medium, that is, the recording area. The recording medium Pr is attracted to the suction platen 28 by the negative pressure suction force acting on the two suction holes 28a1 provided in the suction groove 28a. The suction platen 28 has a configuration in which a plurality of suction grooves 28a are arranged in the main scanning direction.

In addition, a borderless groove 28c, which is a recess for receiving the ejected ink that protrudes outside the recording medium when performing borderless recording at a predetermined position on the suction platen 28, is formed. It is provided in several places according to the recording medium size. These borderless grooves 28c are formed integrally with the suction platen 28, and are formed to be concave with respect to the recording medium holding surface. The ink ejected to the borderless groove 28c is configured to be introduced into a waste ink storage area (not shown) through an opening 28c1 provided in the borderless groove 28c. The opening 28c1 provided in the borderless groove 28c is subjected to a negative pressure suction force similarly to the suction hole 28a1 provided in the suction groove 28a.
JP-A-61-95966 JP 2002-178542 A JP 2003-326743 A

  However, the ink jet recording apparatus provided with the conventional suction platen has the following problems.

  First, when an ink droplet is ejected from a recording head, an ink jet recording apparatus sometimes ejects droplets smaller than the main droplet at the same time as the main droplet. A small droplet discharged at the same time as the main droplet is called a satellite. Further, mist-like ink droplets may be generated that are smaller than the ink droplets that become satellites. This mist-like ink droplet is called ink mist. The ink mist is caused to flow in the air current in the vicinity of the recording head when ink is ejected, and drifts in the apparatus, thereby causing the inside of the apparatus to become dirty or adhere to the recording medium, thereby degrading the image quality.

  Conventionally, in order to perform borderless recording, the suction platen has been provided with several borderless grooves for receiving ink ejected outside the recording medium at positions corresponding to the side edges for each paper size. ing. The borderless groove is provided with an opening for introducing ink into the waste ink storage area. The negative suction force is applied to the opening to prevent clogging of the opening due to ink, and the ink mist staying in the borderless groove at the time of borderless recording is collected, and the backside of the recording medium is removed. There is an effect to prevent.

  Furthermore, since there is a borderless groove at a position corresponding to various recording medium sizes, the recording medium floats from the recording medium holding surface of the platen by sucking the opening provided in the borderless groove in the same manner as other suction holes. It is possible to prevent the image from being lost and perform stable recording.

  The suction means for the borderless groove generates negative pressure by exhausting from the inside by a fan like the suction hole provided in the suction platen. At this time, the viewpoint of simple configuration, low cost, and noise In addition, the borderless groove and the suction hole are sucked by one fan. For this reason, if a negative pressure required for floating the recording medium such as cockling is maintained, a large suction action also acts on the borderless groove. There has been a problem that satellites and ink mists are affected by the air flow generated by the suction, and are caused to flow toward the outside of the recording medium, degrading the image quality.

  Accordingly, the present invention has been made to solve the above-described problems in the prior art. SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus provided with a suction platen, in which a deterioration in image quality of a recording medium caused by a suction action of an opening provided in a borderless groove is prevented.

  In order to solve the above problems, in the present invention, a conveying unit that conveys a recording medium, a recording head that moves in a direction perpendicular to the conveying direction of the recording medium while ejecting ink, and the recording head are disposed opposite to each other. A platen that holds the back surface of the recording medium, a negative pressure generating means for generating a negative pressure on the platen, and a platen that is formed integrally with the platen and is formed on the recording medium side by the recording head for borderless recording. In the ink jet recording apparatus provided with a borderless groove for receiving the ink ejected to a position protruding outward, the inside of the borderless groove is made negative by the negative pressure generating means, and air is introduced into the borderless groove. Therefore, an air inflow groove extending from the borderless groove to the downstream side of the platen in the recording medium conveyance direction is provided.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the inkjet recording device which prevented the fall of the image quality of the recording medium which arises by the suction effect | action of the opening part provided in the borderless groove | channel.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

  FIG. 1 is a perspective view showing an internal structure of a main body of an ink jet recording apparatus to which a suction platen according to the present invention is applied, and FIGS. 2 and 3 are side views showing the internal structure of the main body of FIG. FIG. 4 is a top view of the platen viewed from above the main body, showing an embodiment of an ink jet recording apparatus to which the present invention is applied.

  5 is an enlarged view showing the borderless groove of the platen at the end of the recording medium in FIG. 4, and FIG. 6 is an enlarged perspective view showing the borderless groove in FIG.

  1 to 3, the ink jet recording apparatus 100 according to the present embodiment includes a transport mechanism 20 that feeds, transports, and discharges a recording medium Pr as a roll-shaped recording medium that is rotatably held. Further, the ink jet recording apparatus 100 includes a paper feed guide 27 for guiding the recording medium during paper feeding, and an image forming mechanism 40 that forms an image on the recording medium conveyed while being held based on image information. Have. During the image formation, the back surface of the recording medium is held by the suction platen 38. The suction platen 38 is supported by the lower case 30. A negative pressure is generated in the suction platen 38 by the suction fan 37 through the lower case 30. The suction fan 37 is incorporated in the suction fan unit 36 and connected to the lower case 30.

  The recording medium to be discharged is guided to a discharge port by a discharge guide 29 and a dust cover roller 32. The dust cover roller 32 is provided on the dust cover 31.

  The roll-shaped recording medium Pr is rotatably held by a roll paper holder (not shown) by a spool shaft 11 and a pair of spool flanges, and one of the spool flanges is slidable along the spool shaft 11 to thereby form a roll-shaped recording medium Pr. The width direction of the recording medium Pr is restricted.

  The transport mechanism 20 is driven and rotated while being pressed by a predetermined pressing force to a transport roller (LF roller) 23 for transporting (paper feeding) the recording medium Pr by a predetermined amount in the sub-scanning direction during image formation. A plurality of pinch rollers 24 are provided. A driving force of a paper feed motor (not shown) is transmitted to a transport roller (LF roller) 23, whereby paper feed, transport, and paper discharge operations are performed.

  The image forming mechanism 40 reciprocates in a direction (main scanning direction) that holds the recording head 41 as an image forming unit (recording unit) and intersects (for example, orthogonally) the recording medium conveyance direction (sub-scanning direction). And a carriage 42 that moves. The recording head 41 performs recording on a recording medium held by a platen 38 disposed at a position facing the recording head 41. The recording head 41 is an ink jet recording head that performs image formation (recording) by discharging ink from a discharge port to a recording medium Pr based on image information. That is, in synchronization with the reciprocating movement of the carriage 42 holding the recording head 41 in the main scanning direction, an image is formed by ejecting ink droplets from the ejection port onto the recording medium Pr by a head driving signal based on the image data. It is configured.

  In the ink jet recording apparatus, the recording medium Pr is transported by a predetermined amount in the sub-scanning direction by the transport mechanism 20, and the recording apparatus 40 forms an image by ejecting ink droplets while reciprocating in the main scanning direction. Has been.

  A plurality of dust cover rollers 32 are provided inside the dust cover 31 so as to be arranged in the main scanning direction. The dust cover roller 32 is disposed at a position higher in the vertical direction than the surface holding the back surface of the recording medium of the suction platen 38 on the transport downstream side of the suction platen 38.

  4 to 6 show the suction platen 38 of the present embodiment.

  The suction platen 38 for holding the back surface of the recording medium Pr during image formation is divided into a plurality of moving directions A of the recording head 41 (carriage 42). The ink jet recording apparatus according to this embodiment includes four suction platens.

  Each suction platen has a different groove arrangement in order to adapt to various recording medium sizes. However, since each of the suction platens has the same function and effect, only one suction platen 38 will be described below unless otherwise specified. The explanation of the suction platen is applied mutatis mutandis.

  The suction platen 38 is fixed in a sealed state via a platen seal as a seal member that abuts (closely contacts) the lower end portion thereof. Here, the longer the suction platen 38 is, the more difficult it is to maintain the accuracy of flatness, and the reason that the mold becomes expensive. In this embodiment, the main scanning is not performed as described above. Divided into a plurality of directions. Such a configuration is advantageous for increasing the size of the image forming apparatus. Each of the divided suction platens has substantially the same configuration.

  As a suction mechanism of the suction platen 38, a suction fan 37 as a suction means is connected via a sealed hollow lower case 30. The suction fan 37 is connected to one end portion of the lower case 30 via a suction fan unit 36 that communicates (communicates) with the inside (hollow part) of the lower case 30. In the present embodiment, a sirocco fan that can easily obtain a high output (static pressure) with a small amount of electric power is used as the suction fan 37.

  The structure of the suction platen 38 includes a suction groove 38a connected in the main scanning direction A and extending in the sub-scanning direction, and a suction extending in the sub-scanning direction at a predetermined number of locations inside the recording medium Pr at the end of the recording medium Pr. A groove 38b is provided. A width y2 of the suction groove 38a in the sub-scanning direction is about 3 mm wider than a nozzle width (recordable area) y1 of the recording head 41 mounted on the carriage 42, and a suction hole 38a1 having a diameter of 3 mm is provided. Further, the downstream end of the suction groove 38b in the sub-scanning direction has a shape extending from the downstream end of the suction groove 38a in the sub-scanning direction, and a suction hole 38b1 having a diameter of 2.5 mm is formed. Is provided.

  Further, borderless grooves 38 c formed as concave portions that are concave from the recording medium holding surface of the suction platen 38 are provided at predetermined positions on the suction platen 38. When the recording medium Pr is on the suction platen 38, the borderless groove 38c located at the side end portion Ps of the recording medium Pr has a groove arrangement such that a part thereof is covered with the recording medium Pr. The width x2 of the borderless groove 38c in the main scanning direction is about 11.5 mm, and the width in the sub scanning direction is the same as the width y2 of the suction groove 38a in the sub scanning direction.

  The borderless groove 38c receives ink ejected from the recording head 41 to a position protruding from the recording medium Pr when recording is performed in an area wider than the recording medium so that no margin is generated at the end of the recording medium Pr. It is. In the borderless groove 38c, an opening 38c1 for guiding ink to the waste ink storage area is provided at a position covered with the recording medium Pr. The ink landing surface of the borderless groove 38c is inclined in the main scanning direction so that the received ink flows toward the opening 38c1, and is formed so as to become deeper from the outside toward the inside of the recording medium Pr. .

  The opening 38c1 also has a suction effect for holding the recording medium Pr on the suction platen 38, similarly to the suction holes 38a1 and 38b1 provided in the suction grooves 38a and 38b. By causing the suction force to act on the opening 38c1, there is an effect of preventing the ink ejected from the recording head 41 from being clogged in the opening 38c1. The suction means of the marginless groove 38c generates a negative pressure by exhausting from the inside by a fan in the same manner as the suction holes 38a1 and 38b1 provided in the suction platen 38. The opening 38c1 and the suction holes 38a1 and 38b1 are sucked by a single fan from the viewpoint of simple configuration, low cost, and noise.

  With the above configuration, the suction negative pressure generated by the suction fan 37 disposed in the ink jet recording apparatus 100 is sucked into the suction holes 38a1 and 38b1 and the opening through the hollow portion of the lower case 30 and the suction platens 38. 38c1. The recording medium Pr is attracted to the platen surface of the suction platen 38 by the negative pressure suction force acting on the suction holes 38a1 and 38b1 and the opening 38c1.

  Here, the width size in the main scanning direction of the recording medium that can be recorded by the ink jet recording apparatus varies widely, and the maximum recording medium size of the ink jet recording apparatus 100 including the suction platen 38 of the present invention is 60 inches. The borderless grooves 38c located at the end of the recording medium are provided in 15 places including the reference side, and the sizes of the recording media that can be bordered are 10 inches, 14 inches, 16 inches, 24 inches, 36 inches, 42 inches, JIS B2, JIS B0, ISO A0, ISO A1.

  In the suction platen 38, it is very important to secure a negative pressure corresponding to these various sizes of recording media. However, when recording a small-size recording medium, negative pressure leaks from the suction holes 38a1 and 38b1 and the opening 38c1 that are not covered with the recording medium. Compared to time. When this negative pressure is weak, the recording medium is lifted, the ink landing position is shifted during image formation, and color unevenness occurs in the image. Further, not only does the contact with the recording head 41 or the carriage 42 occur, the image quality is deteriorated, but the recording medium is not discharged from the discharge port to the outside of the apparatus, but is jammed and jammed. Further, even when the recording medium is automatically cut, a recording medium with weak stiffness will cause a cutting defect if the negative pressure is weak.

  In the ink jet recording apparatus 100 including the suction platen 38, as described above, the suction platen 38 is provided on the back surface of the recording medium Pr in order to keep the distance between the recording head 41 and the recording medium Pr constant, and the negative pressure generating means applies the platen to the platen. Negative pressure is generated. Also, borderless recording is made possible by providing borderless grooves 38 c at several locations on the suction platen 38. For this reason, borderless grooves 38c exist at the left and right ends of the recording medium Pr conveyed during recording, and suck air on the platen.

  The marginless groove 38c is partially covered by the recording medium Pr, and the remaining portion is open. Therefore, in order to maintain the negative pressure necessary for attracting the recording medium Pr to the platen surface, the wind speed or the air volume of the air flowing into the borderless groove 38c must be increased. When the amount of air sucked from the borderless groove 38c is increased in this way, satellites and ink mist having a particle size smaller than that of the main droplet are caused to flow from the main droplet to the outside of the recording medium Pr. As a result, there is a problem in that the image quality is lowered or the image is landed on the margin.

  In order to solve this problem, the present invention proposes to prevent the image quality from being deteriorated by lowering the wind speed or the air volume of the borderless groove 38c which is the edge of the recording medium.

  If the wind speed of the recording area y1 generated in the borderless groove 38c by suction is Vc1, the wind speed Vc1 has a great influence on satellites and ink mist. Therefore, in the ink jet recording apparatus 100 of the present invention, in order to lower the wind speed Vc1, the air inflow groove 38d serving as an air inflow port is formed so as to be recessed from the platen surface downstream of the borderless groove 38c in the recording medium conveyance direction. Was provided.

  One end of the air inflow groove 38d communicates with the borderless groove 38c at a position covered with the recording medium Pr on the platen. The air inflow groove 38d extends to a position outside the recording medium Pr that is not covered by the recording medium Pr on the downstream side in the transport direction B of the recording medium Pr with respect to the area y1 in which recording by the recording head is possible. The other end on the downstream side of the air inflow groove 38d that is not covered by the recording medium Pr is an air inlet (air inlet) that is open at a position spaced downstream from the area y1 where recording by the recording head is possible. Become.

  At this time, the wind speed generated in the air inflow groove 38d outside the recording medium Pr by suction is defined as Vc2. In the present embodiment, the air inflow groove 38d formed at a position covered with the recording medium Pr is extended about 5 mm from the recording area y1 to the downstream side in the conveyance direction in the sub-scanning direction, and the recording medium Pr not covered with the recording medium Pr therefrom. The air inflow groove 38d is formed obliquely toward the outer side. At this time, by moving the air intake port formed outside the recording medium Pr away from the recording area y1 on the platen to the downstream side in the transport direction, the influence of satellites and ink mist received by the airflow flowing into the air inflow groove 38d is reduced. did. By sucking the air on the platen from the air inlet formed outside the recording medium Pr, the air flowing into the opening 38c1 provided in the borderless groove 38c can be dispersed. As a result, the wind speed Vc1 applied to the recording area y1 can be suppressed.

  The air introduction path 38d1 close to the borderless groove 38c of the air inflow groove 38d is covered with the recording medium Pr, and the cross-sectional area 38D1 is small. By changing the cross-sectional area 38D1 of the air introduction path 38d1, the value of the wind speed Vc1 applied to the recording area y1 of the marginless groove 38c can be adjusted.

  The cross-sectional area 38D2 of the air inlet 38d2 that is not covered by the recording medium Pr in the air inflow groove 38d is configured to be larger than the cross-sectional area 38D1 of the air inflow path 38d1. The magnitude relationship between the cross-sectional area 38D2 and the cross-sectional area 38D1 is set so that it does not change even when expansion / contraction due to the environmental difference of the recording medium Pr, skewing, or misalignment at the time of setting the recording medium occurs.

  Here, in an ink jet recording apparatus provided with a suction platen, there is a problem that ink mist generated from the recording head 41 adheres to the back surface of the recording medium when a dark color image is recorded without a border. It has been confirmed that this back stain is worsened when the wind speed Vc1 of the recording area y1 of the borderless groove 38c is lowered to 0.6 m / s or less. Further, it has been confirmed that when the wind speed Vc1 of the recording area y1 of the borderless groove 38c is 1.4 m / s or more, the landing position of the satellite or ink mist is greatly increased from the main droplet toward the outside of the recording medium Pr. ing.

  Therefore, in the present embodiment, the width x1 of the air inflow path 38d1 at the position inside the recording medium Pr of the borderless groove 38c is 1.5 mm, and the depth z1 from the platen paper passing surface is 1 mm. As a result, the wind speed Vc1 applied to the recording area y1 of the borderless groove 38c was about 0.7 to 1.0 m / s. By doing so, it is possible to prevent the image quality from being deteriorated due to the back dirt of the recording medium and the landing deviation of the satellite which occurs when performing borderless recording.

  As described above, according to the present invention, the wind speed Vc1 of the recording area y1 generated by the suction action of the opening 38c1 provided in the borderless groove 38c is suppressed to 0.7 m / s to 1.0 m / s. It is possible to prevent landing deviations of satellites and ink mist that occur during recording. In addition, it is possible to prevent ink mist from adhering to the back surface of the recording medium when performing borderless recording. In addition, the suction can be reduced with a single fan through the suction holes 38a1 and 38b1 provided in the suction grooves 38a and 38b and the opening 38c1 provided in the borderless groove 38c, and the noise level is also reduced. It becomes possible. Therefore, it is possible to provide an ink jet recording apparatus that prevents a reduction in image quality of the recording medium Pr.

1 is a perspective view showing an internal configuration of a main body of an ink jet recording apparatus to which the present invention is applied. It is a side view which shows the main body internal structure of FIG. It is a side view which shows the main body internal structure of FIG. It is a top view which shows the suction platen seen from the main body upper surface of FIG. It is the enlarged view which expanded and showed the borderless groove | channel of FIG. It is the perspective view which expanded and showed the borderless groove | channel of FIG. It is a top view which shows the suction platen seen from the main body upper surface of the conventional inkjet recording device. It is the enlarged view which expanded and showed the borderless groove | channel of FIG.

Explanation of symbols

20 Transport mechanism 37 Suction fan 38 Suction platen 38a Suction groove 1
38b Suction groove 2
38c Borderless groove 38c1 Borderless groove opening 38d Air inflow groove 40 Image forming mechanism 41 Recording head 42 Carriage Pr Recording medium

Claims (9)

Conveying means for conveying the recording medium;
A recording head that moves in a direction perpendicular to the conveyance direction of the recording medium while discharging ink;
A platen disposed opposite to the recording head and holding the back surface of the recording medium;
Negative pressure generating means for generating negative pressure on the platen;
In an inkjet recording apparatus including a borderless groove that is integrally formed with the platen and receives ink ejected to a position protruding to the side of the recording medium by the recording head for borderless recording.
The inside of the marginless groove is made negative pressure by the negative pressure generating means,
An ink jet recording apparatus comprising an air inflow groove extending from the borderless groove to the downstream side in the recording medium transport direction of the platen in order to introduce air into the borderless groove.   The air inflow groove is formed such that, when the recording medium is on the platen, one end thereof communicates with the borderless groove at a position covered by the previous recording medium, and the other end serving as an air intake port is formed on the platen. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is formed outside the recording medium that is not covered with the recording medium.   The inkjet recording apparatus according to claim 2, wherein the air intake port is disposed at a position away from a recordable area of the recording head.   The air inflow groove is provided on the downstream side in the transport direction of the recording medium of each of the plurality of borderless grooves provided at a plurality of positions according to the size of the plurality of recording media. The ink jet recording apparatus according to claim 1. In an inkjet recording apparatus that records on a recording medium using a recording head that ejects ink,
A platen for holding a recording medium at a position facing the recording head;
A recess for receiving ink ejected to a position formed on the platen and protruding from the recording medium by the recording head;
Negative pressure generating means for making the inside of the concave portion negative pressure in order to suck the recording medium into the platen
An air introduction path for introducing air into the concave portion from an air introduction port opened at a position away from an area where recording by the recording head of the platen can be recorded;
An ink jet recording apparatus.   The inkjet recording apparatus according to claim 5, wherein the recording unit performs recording up to a position where the side edge of the recording medium protrudes so as not to generate a margin at an edge of the recording medium side.   The inkjet recording apparatus according to claim 5, wherein a part of the concave portion is covered with a recording medium held by the platen.   The inkjet recording apparatus according to claim 5, wherein the air introduction path is a groove opened to the platen.   The inkjet recording apparatus according to claim 8, wherein a portion other than the air inlet of the groove is covered with a recording medium held by the platen.

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