JP2010089342A - Inkjet recording head and inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce wind ripples in an image without enlarging an inkjet recording device. <P>SOLUTION: A flexible sheet 104 substantially parallel with a recording medium 111 is provided in front in the moving direction of an inkjet recording head 115 moving along the surface of the recording medium 111 to eject liquid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink jet recording head (hereinafter referred to as a “recording head”) that forms a character or an image on a recording medium by ejecting liquid from an ejection port, and an ink jet recording apparatus equipped with the recording head.

  The ink jet recording apparatus includes means for discharging liquid, for example, an electrothermal transducer, and applies at least one drive signal to the electrothermal transducer according to print information.

  This drive signal gives an abrupt temperature rise to the electrothermal transducer and causes the ink near the electrothermal transducer to boil instantaneously. In this recording apparatus, ink droplets are ejected at high speed by rapid bubble growth caused by the phase change of ink at this time, and characters and images are formed on a recording medium.

  With the spread of the Internet and digital cameras in recent years, the demand for high-definition and high-tone color printing is increasing. In response to such demand, as means for obtaining a high-definition and high-gradation image, a method of increasing the resolution by narrowing the arrangement interval of the ejection ports for ejecting ink, and individual ink droplets ejected from each ejection port A method for minimizing the size is known.

Normally, in an ink jet recording apparatus, a turbulent air flow is generated between a recording head and a recording medium as the carriage moves. Due to the influence of this air flow, there is a problem that the ink droplets land on a position deviated from a desired position and the image quality is lowered. In order to solve this problem, there is a technique for reducing landing deviation of ink droplets by providing a member extending in the scanning direction from the end of the print cartridge substantially parallel to the recording medium (see Patent Document 1).
JP 2002-361858 JP

  In order to obtain a high-definition and high-gradation image, it is desirable to form an image by ejecting a very small amount of ink droplets from one ejection port.

  In this case, in order to increase the image forming speed, ink droplets must be ejected from the ejection port at a high frequency, and the carriage on which the recording head is mounted must be scanned and moved at high speed in synchronization with the driving frequency of the recording head. I must.

  In this way, when the carriage is scanned and moved at high speed, air disturbance occurs around the recording head along with the scanning movement, and an air flow is generated between the recording head and the recording medium. Such turbulence in the airflow affects the landing accuracy of the ejected ink droplets, leading to a reduction in image quality.

  Here, FIG. 8 schematically shows an example of an image when the airflow is affected.

  FIG. 8A is a schematic diagram of an image 124a formed on the recording medium 111 with a uniform density by the recording head 115 scanning in the X direction. However, due to the influence of the airflow, actually, as shown in FIGS. 8B and 8C, for example, strip-shaped density unevenness 124b and 124c in which the density is relatively higher than the surroundings in the image are generated.

  Hereinafter, an image defect in which such density unevenness occurs is referred to as “wind pattern”. In addition to the pattern of the wind pattern in FIGS. 8B and 8C, the appearance of the wind pattern varies depending on the mutual positional relationship between the ejection port arrays ejected by the ink droplets, the length of the ejection port array, and the like.

  Currently, ink droplets are becoming smaller in response to demands for higher quality images, but as the drop weight decreases, the ratio of the surface area to the weight in the drop weight-surface area relationship increases. To increase.

  As a result, as the size of the droplets is reduced, the influence of the air flow on the ejected minute ink droplets is increased, so that the wind ripples are remarkably generated and the image quality is deteriorated.

  Thus, FIG. 10 shows the configuration disclosed in Patent Document 1 for the problem that the image quality is deteriorated due to the influence of the airflow.

  As shown in FIG. 10, a carriage skirt 28 extends substantially parallel to the recording medium 12 from the end of the print cartridge 30 in the scanning directions 29 and 29 '. In such a configuration, since the carriage skirt 28 extends in the scanning direction, the entire printing apparatus must be enlarged in order to scan the print cartridge 30.

  An object of the present invention is to provide an ink jet recording head and an ink jet recording apparatus that can solve the above-described problems. One of the purposes is to reduce wind ripples in an image without increasing the size of the ink jet recording apparatus.

  In order to achieve the above object, one embodiment of the present invention provides an ink jet recording head that discharges liquid when moved along a surface of a recording medium, and the recording medium is disposed in front of the moving direction of the ink jet recording head. It has the flexible sheet which becomes parallel, It is characterized by the above-mentioned.

  According to the present invention, it is possible to reduce wind ripples in an ink image formed on a recording medium without increasing the size of the ink jet recording apparatus.

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

(First embodiment)
FIG. 1 is a view showing an ink jet recording head and an ink jet recording apparatus using the ink jet recording head according to the first embodiment of the present invention, and shows an exposed internal structure.

  In FIG. 1, the recording apparatus main body includes an exterior member 101 that forms an outer shell, and a chassis 102 that forms a skeleton of components.

  A guide shaft 107 is supported on the recording apparatus main body, and a carriage 114 is held along the guide shaft 107 so as to be movable in the axial direction (main scanning direction). A recording head 115 is detachably held on the carriage 114.

  Furthermore, ink tanks 112a, 112b, and 112c for supplying ink are detachably mounted on the recording head 115. These ink tanks 112a, 112b, and 112c supply, for example, cyan, magenta, and yellow ink to the recording head 115.

  Further, FIG. 7 shows a cross-sectional view of the ejection portion of the recording head 115.

  As shown in FIG. 7, the ejection portion of the recording head 115 includes a drive substrate 117 and an orifice plate member (flow path forming member) 118 fixed on the drive substrate 117 and having an ink ejection port 120 formed therein. Consists of.

  The driving substrate 117 is fixed on a support member 116 provided on the recording head 115 as shown in FIG. In the orifice plate member 118, a plurality of ink discharge ports 120 are arranged in parallel at predetermined intervals along a direction (sub-scanning direction) orthogonal to the main scanning direction. In the form shown in FIG. 3, five ejection port arrays including a plurality of ink ejection ports 120 arranged in the sub-scanning direction are arranged in the main scanning direction.

  In FIG. 1, a carriage motor 105 for reciprocating the carriage 114 in the main scanning direction is attached to the chassis 102 of the recording apparatus main body. The carriage 114 is engaged with the carriage belt 106, and the carriage belt 106 is driven by the carriage motor 105. Then, the carriage 114 reciprocates along the guide shaft 107 as the carriage belt 106 turns in the forward direction or the reverse direction.

  A home position unit 110 including a recovery system for the recording head 115 is disposed on one side of the scanning area (moving area) of the carriage 114 in the outer area of the recording medium 111 in the main scanning direction.

  The home position unit 110 includes a capping unit for preventing the ink discharge port 120 of the recording head 115 from drying. Further, the unit includes a pump unit that sucks and recovers the ink discharge port 120 so as to remove the stain on the ink discharge port 120 and the inside of the recording head 115, and a wiping unit that removes surface contamination on the ink discharge port 120. .

  The recording apparatus main body includes a paper feed roller 108 and paper discharge rollers 109a and 109b. The paper feeding roller 108 is rotationally driven by the driving unit 119, and the recording medium 111 moves in the sub-scanning direction and is supplied to the image forming area. Then, the recording medium 111 on which image formation with ink has been completed moves while being sandwiched between the discharge rollers 109a and 109b, and is discharged to the outside of the recording apparatus.

  In the present invention, the flexible sheet 104 that can be reciprocated at the same speed as the recording head 115 during scanning of the recording head 115 is formed over the entire scanning area (moving area) of the recording head 115, and the recording sheet 115 is within the recording apparatus main body. It is arranged to circulate in.

  In order to explain the positional relationship between the flexible sheet 104 and the recording head 115, FIG. 2 is a plan view of the recording head 115 viewed from the front, and FIG. 3 is a perspective view of the recording head 115 viewed from below.

  As shown in FIG. 2, the flexible sheet 104 is fixed to the carriage 114 and provided on the same plane as the surface of the orifice plate member 118 on which the ink discharge ports 120 are formed. The flexible sheet 104 exists substantially in parallel with the recording medium 111 over the entire scanning area of the recording head 115, and is wound around the movable rollers 103a and 103b on both outer sides of the scanning area to circulate in the apparatus. Yes. As shown in FIG. 3, the flexible sheet 104 is formed with an opening 121 so as to expose the orifice plate member 118 so as not to prevent ink ejection.

  With such a configuration, the flexible sheet 104 reciprocates at the same speed as the recording head 115 without being bent by the movable rollers 103a and 103b. At this time, the flexible sheet 104 in the moving direction of the recording head 115 is kept substantially parallel to the recording medium 111.

  In order to explain the effect of the flexible sheet 104, FIG. 9 shows the state of the air flow around the recording head 115 and its surroundings when the recording head 115 scans and moves.

  As shown in FIG. 9, in the case of the recording head according to the prior art (in the case of FIG. 9A), there is a relatively wide space in front of the carriage 114 in the scanning direction (forward in the moving direction). Therefore, when the recording head 115 scans in the X direction (right side in the figure), the air intervening in the space collides with the side surface of the carriage 114 and is disturbed in the Z direction from the recording head 115 toward the recording medium 111 side. Air flow 123a is generated.

  A portion 123b of the turbulent airflow flows between the recording head 115 and the recording medium 111 (referred to as a paper interval when the recording medium 111 is paper), affects the ejected ink droplets, and causes image quality. Cause a decline.

  On the other hand, in the case of the first embodiment (in the case of FIG. 9B), an air flow 123a turbulent with the scanning movement of the recording head 115 is generated above the flexible sheet 104 in front of the carriage 114 in the scanning direction. However, the flexible sheet 104 serves as a barrier, and the influence of the turbulent air flow 123a on the ink droplet can be avoided. Further, since the air flow 123b is rectified by the flexible sheet 104 between the flexible sheet 104 and the recording medium 111, a wind pattern is reduced in the image formed on the recording medium 111.

  Although the case where the recording head 115 scans and moves in the X direction (right side in the figure) has been described here, the present invention also scans in the direction opposite to the X direction (left side in the figure) to generate an ink image. The same effect can be obtained when forming.

  In FIG. 3, the length of the flexible sheet 104 in the short direction is shown to be approximately the same as the width of the recording head 115 in the sub-scanning direction. However, a configuration in which the flexible sheet 104 extends in a direction perpendicular to the scanning direction of the recording head is more preferable. That is, the length of the flexible sheet 104 in the short direction is preferably equal to or greater than the length of the recording head 115 in the discharge port arrangement direction.

  According to this configuration, turbulent air in front of the carriage 114 in the scanning direction can be more effectively suppressed from flowing into the inter-paper area, and therefore, the influence of the airflow on the ejected ink droplets is further reduced, and the wind pattern is reduced. It can be reduced more.

  In this embodiment, the carriage 114 is scanned by the carriage motor 105 via the carriage belt 106. However, instead of this configuration, a configuration in which the carriage motor 105 is coupled to the movable rollers 103a and 103b and the carriage 114 is scanned using the flexible sheet 104 as a carriage belt may be employed.

  The flexible sheet 104 can be applied to any material that can be bent flexibly, has a relatively high mechanical strength, and is not subject to ink corrosion, such as resin films represented by polyimide, PET, and PP. can do.

(Second embodiment)
FIG. 4 is a diagram showing an ink jet recording head and an ink jet recording apparatus using the ink jet recording head in the second embodiment of the present invention. In the present embodiment, the configuration other than the flexible sheet is the same as that of the first embodiment.

  The flexible sheet 104 of the present embodiment has an end portion, and a portion other than the end portion exists substantially in parallel with the recording medium 111 over the entire scanning region of the recording head 115. As in the first embodiment, the flexible sheet 104 reciprocates at the same speed as the recording head 115 when the recording head 115 is scanned. The flexible sheet 104 in the moving direction of the recording head 115 is kept substantially parallel to the recording medium 111.

  As shown in FIG. 4, a first movable roller 103a and a second movable roller 103b are provided at the left and right ends of the chassis 102. Outside the scanning region of the recording head 115, the left and right ends of the flexible sheet 104 are respectively wound around the second movable roller 103b and wound around the first movable roller 103a by a spring or the like.

  Therefore, in FIG. 4, when the recording head 115 scans and moves to the right side of the drawing, the displacement accompanying the movement of the flexible sheet 104 is wound around and stored in the first movable roller 103a. On the other hand, when the recording head 115 scans and moves to the left side of the drawing, the stored flexible sheet 104 is stretched from the first movable roller 103a.

  In such a configuration, since the flexible sheet 104 does not extend above the recording head 115, the recording head 115 and the ink tanks 112a, 112b, 112c, and 112d are not hindered. Therefore, similarly to the first embodiment, the influence of turbulent air due to the scanning of the carriage 114 can be suppressed with respect to the ejected ink droplets, and the wind pattern in the ink image on the recording medium can be reduced.

  In the present embodiment, the positional relationship between the flexible sheet 104 and the recording head in the vicinity of the recording head 115 is the same as that of the first embodiment, as shown in FIGS. That is, the flexible sheet 104 in the scanning region is provided without being bent in the same plane as the surface of the orifice plate member 118, and the orifice plate member 118 is exposed so as not to prevent ink ejection. In addition, an opening 108 is provided.

(Third embodiment)
FIG. 5 is a diagram showing an inkjet recording head and an inkjet recording apparatus using the inkjet recording head according to a third embodiment of the present invention. In the present embodiment, the configuration other than the flexible sheet is the same as that of the first embodiment.

  FIG. 6 is a diagram showing a relative positional relationship between the recording head 115 and the flexible sheet 104 in the present embodiment.

  As shown in FIGS. 5 and 6, there are two flexible sheets 104, which are flush with the surface of the orifice plate member 108 over the entire scanning section of the recording head 115 on the front and rear sides of the recording head 115 in the scanning direction. It is provided above. Both flexible sheets 104 exist substantially parallel to the recording medium 111 over the entire scanning area of the recording head 115.

  In order to reciprocate the flexible sheet 104 together with the recording head 115 during scanning of the recording head 115, a first movable roller 103a and a second movable roller 103a are provided on each side surface of the carriage 114 in the main scanning direction as shown in FIG. The movable roller 103b is fixed.

  The end of the flexible sheet 104 on the side surface of the recording apparatus main body is fixed to the inner surface of the exterior 101. On the other hand, the flexible sheet 104 on the carriage 114 side is wound up above the recording head 115 along the side surface in the main scanning direction of the carriage 114 by the second movable roller 103b, and an end portion is a spring or the like by the first movable roller 103a. It is wound up by.

  Therefore, in FIG. 5 or FIG. 6, when the recording head 115 scans and moves to the right side of the drawing, the displacement due to the movement of the flexible sheet 104 is wound around and stored in the first movable roller 103a. On the other hand, when the recording head 115 scans and moves to the left side of the drawing, the stored flexible sheet 104 is stretched from the first movable roller 103a.

  In order to explain the effect of such a configuration, FIG. 9C schematically shows the state of the airflow around the recording head 115. In the present embodiment, the flexible sheet 104 does not translate in the main scanning direction of the recording head 115 with respect to the recording medium 111. That is, the flexible sheet 104 does not have a speed relative to the recording medium 111. Therefore, the air flow 123b hardly occurs between the flexible sheet 104 and the recording medium 111. Therefore, the influence of the airflow on the ejected ink droplets can be further suppressed, and the wind pattern in the ink image formed on the recording medium 111 can be effectively reduced.

  Also in this configuration, similarly to the first and second embodiments, the flexible sheet 104 serves as a barrier against the ejected ink droplets, and the carriage 114 scans forward in the scanning direction as the carriage 114 scans. Air flow effects can be avoided. For this reason, the wind pattern in the ink image is reduced.

  In addition, compared to the first and second embodiments, the present embodiment makes the configuration of the flexible sheet 104 smaller, and can reduce the wind pattern in the ink image without increasing the size of the entire recording apparatus. More preferred.

1 is a diagram illustrating an ink jet recording head and an ink jet recording apparatus according to a first embodiment of the present invention. The figure which shows the relative positional relationship of the inkjet recording head and flexible sheet in 1st embodiment of this invention, and 2nd embodiment. The perspective view seen from the downward direction of the inkjet recording head in 1st embodiment of this invention and 2nd embodiment. The figure which shows the inkjet recording head and inkjet recording device by 2nd embodiment of this invention. It is a figure which shows the inkjet recording head and inkjet recording device by 3rd embodiment of this invention. The figure which shows the relative positional relationship of the inkjet recording head and flexible sheet in 3rd embodiment of this invention. FIG. 3 is a partially enlarged cross-sectional view of a discharge port portion of the inkjet recording head of the present invention. (A) is a schematic diagram of an image formed on a recording medium with a uniform density, and (b) is an image obtained by forming print data with a uniform density on the recording medium in one pass depending on the ink ejection state. FIG. 4C is a schematic diagram illustrating an example of a wind pattern, and FIG. 8C is a schematic diagram illustrating an example of a wind pattern that can be seen in an image in which print data having a uniform density is formed on a recording medium in one pass depending on an ink ejection state. (A) is a schematic diagram showing a state of airflow around the recording head when the conventional recording head is scanned, and (b) is a scanning by the recording head in the first embodiment and the second embodiment of the present invention. FIG. 6C is a schematic diagram showing the airflow around the recording head when the recording head scans in the third embodiment of the present invention. It is a schematic diagram which shows the structure which controls the airflow by a prior art.

Explanation of symbols

103, 103a, 103b Movable roller
104 Flexible sheet
111 Recording media
114 carriage
115 recording head
120 outlet
121 opening

Claims (14)

In an inkjet recording head that discharges liquid when moved along the surface of a recording medium,
An ink jet recording head comprising a flexible sheet parallel to the recording medium in front of the ink jet recording head in the moving direction.   The inkjet recording head according to claim 1, wherein the flexible sheet moves at the same speed as the inkjet recording head.   The inkjet recording head according to claim 1, wherein the flexible sheet does not have a speed relative to the recording medium.   4. The ink jet recording head according to claim 1, wherein the flexible sheet is formed over the entire moving region of the ink jet recording head. 5.   6. The ink jet recording head according to claim 1, wherein the flexible sheet extends on the same plane as a surface on which the liquid ejection port of the ink jet recording head is formed. .   7. The ink jet recording head according to claim 1, wherein a length of the flexible sheet in a short direction is equal to or longer than a length of the ink jet recording head in the ejection port arrangement direction.   The inkjet recording head according to claim 5, wherein the flexible sheet has an opening so as to expose a region where the discharge port is formed.   An ink jet recording head according to any one of claims 1 to 7 is mounted, moved along the surface of a recording medium, and liquid is ejected from the ink jet recording head onto the recording medium. An ink jet recording apparatus for forming   The inkjet recording apparatus according to claim 8, further comprising a movable roller that circulates the flexible sheet so as to circulate within the apparatus main body.   The inkjet recording apparatus according to claim 8, further comprising a movable roller that winds and stores an end portion of the flexible sheet.   The inkjet recording apparatus according to claim 10, wherein the flexible sheet accommodated in the movable roller is extended from the movable roller as the inkjet recording head moves.   12. The ink jet recording apparatus according to claim 10, wherein the movable roller is provided on a carriage that moves by mounting the ink jet recording head.   The inkjet recording apparatus according to claim 9, wherein the movable roller is provided in a component of the inkjet recording apparatus.   The inkjet recording apparatus according to claim 13, wherein the component is a chassis of the inkjet recording apparatus.

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