JP2016124256A - Recording head and ink jet recording apparatus provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording head that can suppress shavings of a water-repellent film from entering a discharge nozzle and suppress image quality from deteriorating.SOLUTION: The recording head comprises an ink discharge surface including a nozzle region R to which a plurality of discharge nozzles 18 open. The nozzle region R is provided with a plurality of nozzle rows T having a plurality of discharge nozzles 18 arranged linearly. On the ink discharge surface are formed holes 20 which have hole diameters equal to 10 μm or more and equal to 30 μm or less in the same line as the nozzle rows T and at positions close to an upstream side in a wiping direction relative to the nozzle rows T. The holes 20 are formed in three or more numbers on each nozzle row T, and arranged within 30 mm from the discharge nozzle 18b at the most upstream side in the wiping direction on each nozzle row T.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a recording head having an ejection nozzle that ejects ink onto a recording medium such as paper, and an ink jet recording apparatus including the recording head.

  2. Description of the Related Art As a recording apparatus such as a facsimile, a copying machine, and a printer, an ink jet recording apparatus that forms an image by ejecting ink is widely used because it can form a high-definition image.

  In such an ink jet recording apparatus, there is a case where the straight performance of the ink is deteriorated (flying bending), non-ejection, etc., and the printing performance of the recording head is deteriorated. This may be caused by foreign matters such as paper dust, dust, and dust generated during conveyance of the paper (recording medium), minute ink droplets (hereinafter referred to as mist) ejected together with ink droplets for image recording, The occurrence of meniscus abnormality due to the rebound mist generated when the ink droplets adhere to the recording medium adhere to the ink discharge surface of the recording head can be considered. Further, this may be caused by a decrease in hermeticity at the time of cap mounting due to mist adhering to the cap mounting portion and drying, and an accompanying increase in the viscosity of ink in the nozzle.

  Therefore, in order to prevent ink from being dried in the discharge nozzles with openings on the ink discharge surface of the recording head and clogging of the nozzles due to thickening of the ink in the discharge nozzles, the ink is forced out of the nozzles. A configuration is used in which, after (purging), the purge ink adhering to the ink ejection surface (nozzle surface) is wiped with a wiper to perform a recovery process of the recording head.

  For example, Patent Document 1 discloses a configuration in which after the ink is forcibly pushed out from the ejection nozzle, the purge ink adhering to the ink ejection surface is wiped with a wiper and the recovery process of the recording head is performed. In Patent Document 1, in order to perform wiping in a state where the wiper blade is wet, a dummy nozzle that is not used in printing is provided upstream of the printing nozzle in the movement direction (wiping direction) of the wiper blade, and recovery processing is performed. Sometimes ink is pushed out of the dummy nozzle.

JP 2006-218748 A

  However, even when the recording head that performs the recovery process is used, if the number of printed sheets reaches from several thousand to about 10,000, the ink landing position accuracy with respect to the recording medium decreases and the image quality decreases. There is a problem that there are cases. As a result of various studies on the recording head, the present inventor has found that when the wiper is moved while being pressed against the ink ejection surface during the recovery process of the recording head, the water-repellent film provided on the ink ejection surface is scraped and repelled. It has been found that water film shavings may enter the discharge nozzle and the ink landing position accuracy may decrease.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to suppress the water-repellent film shavings from entering the discharge nozzle and to suppress degradation of the image quality. It is an object of the present invention to provide a recording head that can be used and an ink jet recording apparatus including the recording head.

  In order to achieve the above object, a recording head of the present invention is a recording head having an ink ejection surface including a nozzle region in which a plurality of ejection nozzles that eject ink onto a recording medium are opened. A water repellent film is provided on the ink ejection surface. The nozzle region is provided with a plurality of nozzle rows in which a plurality of ejection nozzles are linearly arranged along the wiping direction, which is the direction in which the wiper wipes the purge ink forcedly ejected from the ejection nozzles. On the ink ejection surface, a hole having a hole diameter of 10 μm or more and 30 μm or less is formed on the same straight line as the nozzle row and at a position upstream of the nozzle row in the wiping direction. Three or more holes are provided for each nozzle row, and are arranged at a position within 30 mm from the most upstream discharge nozzle in the wiping direction with respect to each nozzle row.

  According to the present invention, it is possible to suppress the shavings of the water-repellent film from entering the discharge nozzle, and thus it is possible to suppress the ink landing position accuracy with respect to the recording medium from being lowered and the image quality from being lowered. .

The figure which shows the structure of the inkjet recording device which concerns on one Embodiment of this invention. The figure which looked at the 1st conveyance unit and recording part of the ink-jet recording device shown in Drawing 1 from the upper part View of the recording unit from diagonally above Diagram of the recording head that constitutes the line head of the recording unit View of the recording head viewed from the ink ejection surface Diagram showing the structure around the discharge nozzle and hole of the recording head View of the discharge nozzle and hole area of the print head viewed from the ink discharge surface side A view of the wiping mechanism mounted on the maintenance unit from above. The figure which looked at the carriage which constitutes the wiping mechanism from diagonally above The figure which shows the state which removed the wiping mechanism from the unit housing | casing of the maintenance unit It is a figure of the raising / lowering mechanism arrange | positioned at a unit housing | casing, and is a figure which shows the state which has a lift member in a horizontal state It is a figure of the raising / lowering mechanism arrange | positioned at a unit housing | casing, and is a figure which shows the state which the lift member stood up from the state of FIG. Diagram of lift members that constitute the lifting mechanism The figure which shows the state which has arrange | positioned the maintenance unit under the recording part The figure which shows the carriage, wiper, support frame, raising / lowering mechanism in the maintenance unit in the state of FIG. FIG. 15 is a diagram illustrating a state where the support frame and the carriage are lifted by the lifting mechanism from the state of FIG. 15 and the wiper is disposed in contact with the ink discharge surface. Diagram of the recording head showing a state in which the wiper is disposed below the first position FIG. 17 is a diagram of the recording head when the ink ejection surface in the state of FIG. 17 is viewed from below. FIG. 7 is a diagram of a recording head showing a state where the wiper is moved in the direction of arrow A while being in pressure contact with the ink ejection surface. FIG. 19 is a diagram of the recording head showing a state where the wiper is moved from the state of FIG. 19 to the downstream edge in the wiping direction. FIG. 20 is a diagram of the recording head showing a state where the wiper is separated from the ink ejection surface from the state of FIG. The figure which shows the state which a support frame and a carriage descend | fall by the raising / lowering mechanism, and the wiper was spaced apart from the ink discharge surface.

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

  As shown in FIG. 1, a paper feed tray 2 for storing paper S (recording medium) is provided on the left side of the ink jet recording apparatus 100 according to an embodiment of the present invention. In this case, the accommodated sheets S are conveyed one by one from the uppermost sheet S one by one to a first conveying unit 5 to be described later, and the sheet feeding roller 3 is in pressure contact with the sheet feeding roller 3 and is driven to rotate. A driven roller 4 is provided.

  A first transport unit 5 and a recording unit 9 are disposed on the downstream side (right side in FIG. 1) of the paper feed roller 3 and the driven roller 4 with respect to the paper transport direction (arrow X direction). The first transport unit 5 includes a first drive roller 6, a first driven roller 7, and a first transport belt 6 that is stretched over the first drive roller 6 and the first driven roller 7. When the first drive roller 6 is driven to rotate in the clockwise direction by a control signal from the control unit 110 of the recording apparatus 100, the paper S held on the first transport belt 8 is transported in the arrow X direction.

  The recording unit 9 includes a head housing 10 and line heads 11C, 11M, 11Y, and 11K held by the head housing 10. These line heads 11C to 11K are supported at such a height that a predetermined interval (for example, 1 mm) is formed with respect to the conveyance surface of the first conveyance belt 8, and as shown in FIGS. A plurality (three in this case) of recording heads 17a to 17c are arranged in a staggered manner along the paper width direction (vertical direction in FIG. 2) perpendicular to the transport direction. 3 shows a state in which the recording unit 9 is viewed from the back side in FIG. 1 (upper side in FIG. 2), and the arrangement of the line heads 11C to 11K is opposite to that in FIGS.

  As shown in FIGS. 4 and 5, a nozzle region R in which a large number of ejection nozzles 18 (see FIG. 2) are arranged is provided on the ink ejection surfaces F of the recording heads 17a to 17c. Since the recording heads 17a to 17c have the same shape and configuration, the recording heads 17a to 17c are shown in one drawing in FIGS. 4 and 5 and FIG. The detailed structure of the ink ejection surface F of the recording heads 17a to 17c will be described later.

  In the recording heads 17a to 17c constituting the line heads 11C to 11K, inks of four colors (cyan, magenta, yellow, and black) stored in ink tanks (not shown) are respectively stored in the line heads 11C to 11K. Supplied for each color.

  Each of the recording heads 17a to 17c is transported while being sucked and held on the transport surface of the first transport belt 8 in accordance with image data received from an external computer by a control signal from the control unit 110 (see FIG. 1). Ink is ejected from the ejection nozzle 18 toward the end. As a result, a color image in which four colors of cyan, magenta, yellow, and black are superimposed is formed on the sheet S on the first conveying belt 8.

  Further, in order to prevent ink discharge failure due to drying or clogging of the recording heads 17a to 17c, the printing nozzles of all the recording heads 17a to 17c can be started from the discharge nozzles 18 at the start of printing after being stopped for a long time. Is prepared for the next printing operation by executing a purge that pushes out the ink with increased viscosity in the discharge nozzles 18 from the discharge nozzles 18 of the recording heads 17a to 17c whose ink discharge amount is not more than a specified value.

  As shown in FIG. 5, the ink ejection surfaces F of the recording heads 17a to 17c are provided with a nozzle region R in which ejection nozzles 18 (see FIG. 2) are provided and a plurality of holes 20 (see FIG. 6). And a hole region R20.

  As shown in FIG. 6, the nozzle region R of the ink discharge surface F is provided with a plurality of discharge ports 18 a having a minute diameter (for example, 20 μm) that are openings of the discharge nozzles 18.

  In addition, the recording heads 17a to 17c are provided with a nozzle channel 76 that communicates a plurality of ejection nozzles 18 and an ink tank (not shown) for storing ink, as well as a common electrode, a piezoelectric element (not shown), Individual electrodes and the like are provided, and the ink discharge operation is controlled for each discharge nozzle 18. Further, a water repellent film 73 is provided on the ink discharge surface F so as to cover portions other than the discharge ports 18 a and the holes 20.

  The discharge nozzle 18 and the hole 20 are formed by subjecting a plate-like member 74 made of SUS or the like constituting the ink discharge surface F to drilling (for example, drilling). Unlike the discharge nozzle 18, the hole 20 does not communicate with the nozzle flow path 76.

  As shown in FIG. 7, in the nozzle region R, the discharge nozzles 18 are linearly arranged along the longitudinal direction of the ink discharge surface F (the left-right direction in FIG. 7, the wiping direction of wipers 35a to 35c described later). A plurality of nozzle rows T are provided. The nozzle rows T are arranged at a predetermined interval in the short side direction (up and down direction in FIG. 7) of the ink ejection surface F.

  The hole region R20 is disposed adjacent to the right side of the nozzle region R (upstream side in the wiping direction of wipers 35a to 35c described later). The holes 20 are arranged on the same straight line as the nozzle row T in the hole region R20. The holes 20 have a hole diameter (diameter) of 10 μm or more and 30 μm or less, and three or more (here, three) holes are provided for each nozzle row T. The hole 20 preferably has the same 20 μm hole diameter (diameter) as the discharge nozzle 18.

  Moreover, the hole 20 is arrange | positioned with respect to each nozzle row T in the area | region of L (= 30 mm or less) from the most upstream discharge nozzle 18b of the wiping direction of the wipers 35a-35c mentioned later. The holes 20 are preferably arranged in an area of 10 mm or less from the most upstream discharge nozzle 18b with respect to each nozzle row T.

  The holes 20 are arranged with a substantially equal pitch L20 (here, L20 = L / 3) from the most upstream discharge nozzle 18b with respect to each nozzle row T. The pitch L20 of the holes 20 is larger than the pitch L18 (for example, 0.5 mm to 1.0 mm) of the discharge nozzle 18.

  Returning to FIG. 1, the second transport unit 12 is arranged on the downstream side (right side in FIG. 1) of the first transport unit 5 with respect to the paper transport direction. The second transport unit 12 includes a second drive roller 13, a second driven roller 14, and a second transport belt 15 stretched over the second drive roller 13 and the second driven roller 14. When the two drive rollers 13 are rotationally driven in the clockwise direction, the paper S held on the second transport belt 15 is transported in the arrow X direction.

  The paper S on which the ink image is recorded by the recording unit 9 is sent to the second transport unit 12, and the ink ejected on the surface of the paper S while passing through the second transport unit 12 is dried. A maintenance unit 19 and a cap unit 90 are disposed below the second transport unit 12. The maintenance unit 19 moves below the recording unit 9 when performing the above-described purge, wipes the ink pushed out from the ejection nozzles 18 of the recording heads 17a to 17c, and collects the wiped ink. The cap unit 90 horizontally moves below the recording unit 9 when capping the ink ejection surfaces F (see FIG. 4) of the recording heads 17a to 17c, and further moves upward to be attached to the lower surfaces of the recording heads 17a to 17c. Is done. The detailed configuration of the maintenance unit 19 will be described later.

  Further, on the downstream side of the second transport unit 12 with respect to the paper transport direction, a discharge roller pair 16 that discharges the paper S on which an image is recorded to the outside of the apparatus main body is provided. Is provided with a discharge tray (not shown) on which the sheets S discharged outside the apparatus main body are stacked.

  A wiping mechanism 30 shown in FIG. 8 is mounted on the maintenance unit 19. The wiping mechanism 30 includes a substantially rectangular carriage 31 to which a plurality of wipers 35 a to 35 c (see FIG. 9) are fixed, and a support frame 40 that supports the carriage 31. Rail portions 41a and 41b are formed at opposing edges of the upper surface of the support frame 40. The sliding rollers 36 provided at the four corners of the carriage 31 abut against the rail portions 41a and 41b. The support frame 40 is slidably supported in the direction of the arrow AA ′.

  As shown in FIG. 9, the carriage 31 includes first stays 32 a and 32 b that are slidably engaged with rail portions 41 a and 41 b of the support frame 40 via a slide roller 36, and first stays 32 a and 32 b. The second stays 33a, 33b, and 33c fixed in a bridging manner are formed in a frame shape.

  Rack teeth 38 that mesh with the input gear 43 (see FIG. 8) held by the support frame 40 are formed on the first stay 32a. When the input gear 43 rotates in the forward and reverse directions, the carriage 31 reciprocates in the horizontal direction (the direction of the arrow AA ′ in FIG. 8) along the support frame 40.

  The wipers 35a to 35c are members for wiping off the ink pushed out from the ejection nozzles 18 of the recording heads 17a to 17c. The wipers 35a to 35c are in pressure contact with the positions outside the nozzle region R and the hole region R20 (see FIG. 5) from a substantially vertical direction, and move the carriage 31 along the ink discharge surface F including the nozzle region R in a predetermined direction (FIG. 8). Wipe in the direction of arrow A).

  Four wipers 35a are fixed to the second stay 33a at substantially equal intervals. Similarly, four wipers 35b are substantially fixed to the second stay 33b, and four wipers 35c are substantially omitted to the second stay 33c. Fixed at regular intervals. The wipers 35a and 35c are disposed at positions corresponding to the left and right recording heads 17a and 17c (see FIG. 3) constituting the line heads 11C to 11K, respectively. The wiper 35b is disposed at a position corresponding to the central recording head 17b (see FIG. 3) constituting each of the line heads 11C to 11K, and the movement direction of the carriage 31 (see FIG. 8) with respect to the wipers 35a and 35c. It is fixed by being shifted by a predetermined distance in a direction orthogonal to the direction of arrow AA ′.

  As shown in FIG. 9, gap rollers 37 are provided at four locations on the upper surfaces of the second stays 33a and 33c. The gap roller 37 contacts the head housing 10 of the recording unit 9 when the wiping mechanism 30 is raised to the recording unit 9 side in order to perform the wiping operation of the ink discharge surfaces F of the recording heads 17a to 17c by the wipers 35a to 35c. The contact state between the wipers 35a to 35c and the ink discharge surface F is kept constant by contact.

  Next, the elevating mechanism 50 for elevating the wiping mechanism 30 of this embodiment will be described. The maintenance unit 19 includes a unit casing 45 shown in FIG. 10, a wiping mechanism 30 (see FIG. 8) attached to the unit casing 45, and an elevating mechanism 50 disposed in the unit casing 45. As shown in FIGS. 10 and 11, an elevating mechanism 50 having two lift members 50a fixed to both ends of the shaft 50b is provided on the bottom surface 45a of the unit housing 45 in the moving direction of the carriage 31 (arrow AA in FIG. 8). A pair is disposed along the side surfaces 45b and 45c facing each other in the 'direction'. That is, the elevating mechanism 50 is disposed at a position facing both ends in the width direction of the head housing 10 of the recording unit 9 (upper and lower ends in FIG. 2). In FIG. 10, the lifting mechanism 50 on the side surface 45c is not shown. The side surface 45d adjacent to the side surfaces 45b and 45c of the unit housing 45 is provided with a motor 47 and a drive transmission shaft 48 that transmits the rotational driving force of the motor 47 to the shaft 50b.

  As shown in FIG. 13, the lower end portion of the lift member 50a is fixed to the shaft 50b, and the lift member 50a swings as the shaft 50b rotates. A push-up roller 53 is rotatably attached to the upper end portion of the lift member 50a. The push-up roller 53 is urged by a coil spring 55 in a direction away from the shaft 50b (upward in FIG. 13).

  When the shaft 50b of the right elevating mechanism 50 is rotated in the clockwise direction and the shaft 50b of the left elevating mechanism 50 is rotated counterclockwise from the state of FIG. The lift member 50a rises in the outer direction (arrow B direction) and is switched from the horizontal state to the upright state (the state shown in FIG. 12), and raises the carriage 31 together with the support frame 40.

  On the other hand, when the shaft 50b of the right elevating mechanism 50 is rotated in the counterclockwise direction and the shaft 50b of the left elevating mechanism 50 is rotated in the clockwise direction from the state shown in FIG. The lift member 50a is tilted in the direction of the arrow B ', and the lift member 50a is switched from the standing state to the horizontal state (the state shown in FIG. 11), and the carriage 31 is lowered together with the support frame 40.

  Next, the recovery operation of the recording heads 17a to 17c using the wiping mechanism 30 in the inkjet recording apparatus 100 of the present embodiment will be described. 15, 16, and 22 show a state in which the recording unit 9 and the maintenance unit 19 are viewed from the downstream side in the sheet conveyance direction (left side in FIG. 14). Further, the support frame 40 is simplified and described in a plate shape, and the unit housing 45 describes only the bottom surface 45a. Further, the recovery operation and the cap unit mounting operation of the recording heads 17a to 17c described below are performed based on the control signal from the control unit 110 (see FIG. 1), the recording heads 17a to 17c, the wiping mechanism 30, the lifting mechanism 50, and the like. It is executed by controlling the operation of

  When the recovery operation of the recording heads 17a to 17c is performed, first, the first transport unit 5 positioned below the recording unit 9 is lowered as shown in FIG. Then, the maintenance unit 19 disposed below the second transport unit 12 is moved horizontally and disposed between the recording unit 9 and the first transport unit 5. In this state, as shown in FIG. 15, the lift member 50a of the elevating mechanism 50 is in a horizontal state, and the wipers 35a to 35c fixed to the carriage 31 are separated from the ink ejection surface F of the recording heads 17a to 17c. .

(Ink extrusion operation)
Prior to the wiping operation (wiping operation described later), the ink 22 is supplied to the recording heads 17a to 17c. As shown in FIG. 17, the supplied ink 22 is forcibly extruded (purged) from the discharge nozzle 18. By this purging operation, the thickened ink, foreign matter and bubbles in the discharge nozzle 18 are discharged, and the recording heads 17a to 17c can be recovered. At this time, as shown in FIG. 18, the purge ink 22 a is pushed out to the ink discharge surface F along the shape of the nozzle region R where the discharge nozzle 18 exists.

(Wiping operation)
The wipers 35a to 35c are brought into contact with the first position P1 outside the nozzle region R and the hole region R20 on the ink ejection surface F of the recording heads 17a to 17c with a predetermined pressure. Specifically, as shown in FIGS. 16 and 17, the support frame 40 and the carriage 31 are lifted by rotating the shaft 50 b of the elevating mechanism 50 and raising the lift member 50 a in the arrow B direction. At this time, since the gap roller 37 provided on the carriage 31 is pressed against the lower surface of the head housing 10 by the biasing force of the coil spring 55 (see FIG. 13) of the lift member 50a, the wipers 35a to 35c are moved against the ink discharge surface F. It is always possible to press contact with a constant pressure.

  From the state where the tips of the wipers 35a to 35c are in pressure contact with the ink ejection surface F, the input gear 43 (see FIG. 8) is rotated forward to move the carriage 31 in the direction of arrow A in FIG. The wipers 35a to 35c also move in the direction of the nozzle region R (left direction, wiping direction) along the ink ejection surface F as shown in FIG. Since an upward force is applied to the support frame 40 by the lifting mechanism 50, the carriage 31 moves in the arrow A direction while maintaining the state where the gap roller 37 is pressed against the head housing 10.

  Then, as shown in FIG. 20, the wipers 35a to 35c move to the left (in the direction of arrow A) while wiping the purge ink 22a on the ink ejection surface F while maintaining the state in contact with the ink ejection surface F. When reaching the edge of the discharge surface F (left edge in FIG. 20), the movement in the left direction is stopped. The waste ink wiped off by the wipers 35a to 35c is collected in an ink collection tray (not shown).

(Separation operation)
After execution of the wiping operation, the wipers 35a to 35c are separated from the ink ejection surface F as shown in FIG. Specifically, as shown in FIG. 22, the shaft 50b of the lifting mechanism 50 is rotated to cause the lift member 50a to fall in the direction of the arrow B ′, thereby causing the wipers 35a to 35c to eject ink from the recording heads 17a to 17c. The maintenance unit 19 is returned to the state shown in FIG. Finally, the maintenance unit 19 disposed between the recording unit 9 and the first transport unit 5 is moved horizontally and disposed below the second transport unit 12 to raise the first transport unit 5 to a predetermined position. Thus, the recovery operation of the recording heads 17a to 17c is completed.

  When the cap unit 90 is attached to the recording heads 17a to 17c, first, as shown in FIG. 14, the first belt conveyance unit 5 disposed to face the lower surface of the recording unit 9 is lowered. Then, the cap unit 90 disposed below the second belt conveyance unit 12 is horizontally moved between the recording unit 9 and the first belt conveyance unit 5 and disposed at a position facing the recording unit 9.

  Next, the cap unit 90 is pushed up by raising the first belt conveyance unit 5. Then, when the cap unit 90 comes into close contact with the recording heads 17a to 17c, the ascent of the first belt conveyance unit 5 is stopped to complete the mounting of the cap unit 90.

  In the present embodiment, as described above, the ink ejection surface F has a hole diameter of 10 μm or more and 30 μm or less on the same line as the nozzle row T and upstream of the nozzle row T in the wiping direction. The holes 20 are formed, and three or more holes 20 are provided for each nozzle row T, and the nozzle rows T are arranged within 30 mm from the most upstream discharge nozzle 18b in the wiping direction. As a result, when the water repellent film 73 is shaved by the wipers 35a to 35c during the recovery process of the recording heads 17a to 17c, the shavings of the water repellent film 73 enter the holes 20 and accumulate, so the water repellent film 73 is shaved. It is possible to suppress the residue from entering the discharge nozzle 18. For this reason, since it can suppress that the landing position precision of the ink 22 with respect to the paper S falls, it can suppress that image quality falls.

  Further, as described above, the hole diameter of the hole 20 may be approximately the same size (about 20 μm) as the nozzle diameter of the discharge nozzle 18. If comprised in this way, it can suppress more that the landing position precision of the ink 22 with respect to the paper S falls. Moreover, the hole 20 can be easily formed using the same drill in the same process as the discharge nozzle 18.

  Further, as described above, all of the holes 20 may be arranged within 10 mm from the most upstream discharge nozzle 18b with respect to each nozzle row T. If comprised in this way, it can suppress more that the landing position precision of the ink 22 with respect to the paper S falls.

  Further, as described above, the holes 20 are arranged at substantially equal pitches from the most upstream discharge nozzle 18b with respect to each nozzle row T. Thereby, the shavings of the water repellent film 73 can be efficiently accommodated by the holes 20.

  Next, a confirmation experiment performed to confirm the effect of the present embodiment will be described.

[Experiment on presence / absence of hole 20]
First, an experiment regarding the presence or absence of the holes 20 will be described. This confirmation experiment was conducted for Example 1 corresponding to the above embodiment and Comparative Example 1.

Example 1
In Example 1, three holes 20 were provided for each nozzle row T, and the hole diameter (diameter) of the holes 20 was 20 μm. In addition, the holes 20 are arranged in an area of 10 mm (= L) from the most upstream discharge nozzle 18 b with respect to each nozzle row T. That is, the distance between the hole 20 farthest from the nozzle region R of the three holes 20 and the most upstream discharge nozzle 18b is set to 10 mm, and the pitch L20 of the holes 20 is set to about 3.3 mm. The nozzle diameter (diameter) of the discharge nozzle 18 was 20 μm. The other configuration of Example 1 was the same as that of the above embodiment.

(Comparative Example 1)
In Comparative Example 1, no hole 20 was provided on the ink ejection surface F. The other configuration of Comparative Example 1 was the same as that of Example 1.

  For Example 1 and Comparative Example 1, the ink landing position accuracy with respect to the paper S was obtained. Specifically, the amount of misalignment of the dots printed on the paper S from the position where the ink should actually land was measured at the beginning of use of the recording head and when the recovery operation was repeated 12,000 times. Then, from the difference, 3σ of the increase amount of the positional deviation amount (the positional deviation deterioration amount) was calculated, and the landing position accuracy was evaluated. The calculation of the increase amount of the positional deviation amount was performed for three (about 200 in total) on the upstream side (right side) of each nozzle row T and all of the discharge nozzles 18 (about 2700 in total). When the larger value of the increase amount of the positional deviation between the three upstream nozzles T and all of the ejection nozzles 18 is less than 2.0 μm, ◎, 2.0 μm or more and 5.0 μm In the case of less than ◯, it was marked as ◯, and in the case of 5.0 μm or more, it was marked as x. The results are shown in Table 1 below.

  In addition, the level of 5.0 μm or more tends to spread the ink even on the paper surface (even if the landing position shift occurs, the adjacent liquid compensates, so the streaks (dots that appear to be streaked) are not noticeable) Even on plain paper, it is at a level where the streaks can be seen visually. Further, the level of 2.0 μm is a border line indicating whether or not a streak can be visually recognized in a fine coated paper in which ink does not easily spread. In this confirmation experiment, a piece of plain paper that can be visually observed with ordinary paper is marked with ×, and a finely coated paper that may be used for special purposes is marked with ◎. The thing in the meantime was set as (circle) as a problem-free level.

  The reason why the increase amount of the positional deviation amount is calculated for the three discharge nozzles 18 on the upstream side (right side) of each nozzle row T is as follows. That is, in the preliminary survey conducted by the present inventor, it was found that only the three ejection nozzles 18 on the upstream side in the wiping direction of each nozzle row T are likely to deteriorate the ink landing position accuracy. It should be noted that the ink landing position accuracy of only the three discharge nozzles 18 on the upstream side in the wiping direction of each nozzle row T is likely to be deteriorated because almost all of the shaving residue of the water repellent film 73 is on the upstream side. This is considered to be because the fourth and subsequent discharge nozzles 18 can normally discharge.

  In this experiment, black ink containing carbon black having a relatively high hardness as a pigment was used. This is because, in a preliminary survey conducted by the present inventor, when a black ink containing carbon black having a relatively high hardness as compared with other color inks is used as a pigment, the ink landing position accuracy decreases. This is because it was easy to find. In addition, when the black ink is used, the ink landing position accuracy is likely to decrease because the black ink contains carbon black having a relatively high hardness as a pigment, and the water-repellent film 73 is likely to be scraped off. It is believed that there is.

  Referring to Table 1, it has been found that when the hole 20 is not formed, the landing position accuracy is lowered, while the formation of the hole 20 can suppress the drop of the landing position accuracy. In addition, in the first embodiment, three (approximately 200 in total) 3σ (hereinafter referred to as “Ma3σ”) on the upstream side (right side) of each nozzle row T and 3σ (hereinafter referred to as “approximately 3700”) of all the discharge nozzles 18. , Mb3σ) was about 0.5 μm and about 0.4 μm, and Ma3σ and Mb3σ of Comparative Example 1 were about 9.1 μm and about 1.6 μm.

[Experiment regarding the number of holes 20]
Next, an experiment regarding the number of holes 20 will be described. This confirmation experiment was conducted for Examples 1 and 2 and Comparative Examples 2 and 3 corresponding to the above embodiment.

(Example 2)
In Example 2, four holes 20 were provided for each nozzle row T. The distance between the hole 20 farthest from the nozzle region R of the four holes 20 and the most upstream discharge nozzle 18b was 10 mm, and the pitch L20 of the holes 20 was about 2.5 mm. The other configuration of Example 2 was the same as that of Example 1 above.

(Comparative Example 2)
In Comparative Example 2, one hole 20 was provided for each nozzle row T. The distance between the hole 20 and the most upstream discharge nozzle 18b was set to 10 mm. Other configurations in Comparative Example 2 were the same as those in Example 1 above.

(Comparative Example 3)
In Comparative Example 3, two holes 20 were provided for each nozzle row T. The distance between the hole 20 farthest from the nozzle region R of the two holes 20 and the most upstream discharge nozzle 18b was 10 mm, and the pitch L20 of the holes 20 was about 5.0 mm. The other configuration of Comparative Example 3 was the same as that of Example 1 above.

  Then, in Examples 1 and 2 and Comparative Examples 2 and 3, the landing position accuracy was evaluated in the same manner as in the above “experiment regarding presence / absence of hole 20”. The results are shown in Table 2 below.

  Referring to Table 2, it was found that when only one or two holes 20 are formed, the landing position accuracy is lowered, while the formation of three or more holes 20 can suppress a decrease in landing position accuracy. . In addition, Ma3σ and Mb3σ of Example 2 are about 0.4 μm and about 0.4 μm, and Ma3σ and Mb3σ of Comparative Example 2 are about 10.1 μm and about 1.5 μm. Mb3σ was about 9.4 μm and about 0.9 μm.

[Experiment on hole diameter (diameter) of hole 20]
Next, an experiment regarding the hole diameter (diameter) of the hole 20 will be described. This confirmation experiment was conducted for Examples 1, 3, and 4 and Comparative Examples 4 and 5 corresponding to the above embodiment.

Example 3
In Example 3, the hole diameter (diameter) of the hole 20 was set to 10 μm. Other configurations of Example 3 were the same as those of Example 1 above.

Example 4
In Example 4, the hole diameter (diameter) of the hole 20 was set to 30 μm. The other configuration of Example 4 was the same as that of Example 1 above.

(Comparative Example 4)
In Comparative Example 4, the hole diameter (diameter) of the hole 20 was set to 5 μm. Other configurations of Comparative Example 4 were the same as those of Example 1 above.

(Comparative Example 5)
In Comparative Example 5, the hole diameter (diameter) of the hole 20 was set to 40 μm. The other configuration of Comparative Example 5 was the same as that of Example 1 above.

  Then, in Examples 1, 3, and 4 and Comparative Examples 4 and 5, the landing position accuracy was evaluated in the same manner as in the “experiment regarding presence / absence of hole 20”. The results are shown in Table 3 below.

  Referring to Table 3, when the hole diameter (diameter) of the hole 20 is 5 μm or less, or 40 μm or more, the landing position accuracy is lowered, while the hole diameter (diameter) of the hole 20 is 10 μm or more and 30 μm or less. As a result, it was found that the decrease in landing position accuracy can be suppressed. Ma3σ and Mb3σ of Example 3 were about 0.9 μm and about 0.9 μm, and Ma3σ and Mb3σ of Example 4 were about 1.9 μm and about 2.4 μm. In addition, Ma3σ and Mb3σ of Comparative Example 4 were about 6.2 μm and about 1.1 μm, and Ma3σ and Mb3σ of Comparative Example 5 were about 5.5 μm and about 7.1 μm.

  In addition, when the hole diameter (diameter) of the hole 20 is 5 μm or less (Comparative Example 4), since the shavings of the water repellent film 73 cannot be removed by the hole 20, the three upstream discharge nozzles 18 It is considered that the landing position accuracy is lowered. On the other hand, when the hole diameter (diameter) of the hole 20 is 40 μm or more (Comparative Example 5), the tip (upper end) of the wipers 35a to 35c is scratched and left unwiped, resulting in overall landing position accuracy. It is thought to decline.

[Experiment regarding distance between hole 20 and uppermost discharge nozzle 18b]
Next, an experiment regarding the distance between the hole 20 and the most upstream discharge nozzle 18b will be described. This confirmation experiment was conducted for Examples 1 and 5 and Comparative Examples 6 and 7 corresponding to the above embodiment.

(Example 5)
In the fifth embodiment, the holes 20 are arranged in a region 30 mm (= L) from the most upstream discharge nozzle 18b with respect to each nozzle row T. That is, the distance between the hole 20 farthest from the nozzle region R of the three holes 20 and the discharge nozzle 18b was set to 30 mm, and the pitch L20 of the holes 20 was set to about 10.0 mm. The other configuration of Example 5 was the same as that of Example 1 above.

(Comparative Example 6)
In Comparative Example 6, the holes 20 were arranged in a region 40 mm (= L) from the most upstream discharge nozzle 18b with respect to each nozzle row T. That is, the distance between the hole 20 farthest from the nozzle region R of the three holes 20 and the discharge nozzle 18b was 40 mm, and the pitch L20 of the holes 20 was about 13.3 mm. The other configuration of Comparative Example 6 was the same as that of Example 1 above.

(Comparative Example 7)
In Comparative Example 7, the holes 20 are arranged in a region of 50 mm (= L) from the uppermost discharge nozzle 18b with respect to each nozzle row T. That is, the distance between the hole 20 farthest from the nozzle region R of the three holes 20 and the discharge nozzle 18b was 50 mm, and the pitch L20 of the holes 20 was about 16.6 mm. Other configurations of Comparative Example 7 were the same as those of Example 1 above.

  Then, in Examples 1 and 5 and Comparative Examples 6 and 7, the landing position accuracy was evaluated in the same manner as in the “experiment regarding presence / absence of hole 20”. The results are shown in Table 4 below.

  Referring to Table 4, when the distance between the hole 20 farthest from the nozzle region R and the most upstream discharge nozzle 18b is set to 40 mm or more, the landing position accuracy is lowered, while the distance is set to 30 mm or less. It has been found that a decrease in position accuracy can be suppressed. In addition, Ma3σ and Mb3σ of Example 5 are about 2.1 μm and about 0.8 μm, Ma3σ and Mb3σ of Comparative Example 6 are about 6.0 μm and about 1.3 μm, and Ma3σ and Comparative Example 7 are Ma3σ and about 1.3 μm. Mb3σ was about 8.8 μm and about 1.7 μm.

  The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments and examples but by the scope of claims for patent, and includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above-described embodiment, the example in which the hole 20 is formed so as to penetrate the plate-like member 74 has been described. However, the present invention is not limited thereto, and the hole 20 is formed in a concave shape so as not to penetrate the plate-like member 74. May be.

  Moreover, although the example which formed the hole 20 circularly was shown in the said embodiment, this invention is not limited to this, You may form the hole 20 in shapes other than circular, such as a polygon.

  In the above-described embodiment, the example in which the holes 20 are arranged at substantially equal pitches from the discharge nozzles 18b with respect to each nozzle row T has been described. However, the present invention is not limited to this, and the holes 20 are arranged in each nozzle row. With respect to T, it is not necessary to arrange them at substantially equal pitches from the discharge nozzle 18b.

  In the above-described embodiment, an example in which the wipers 35a to 35c move only in one direction (from the right side to the left side) in a state where the wipers 35a to 35c are in pressure contact with the ink ejection surface F has been described, but the present invention is not limited thereto. The wipers 35a to 35c may move in both one direction and the other direction in a state where the wipers 35a to 35c are in pressure contact with the ink discharge surface F. In this case, the holes 20 may be provided on both the left and right sides of the discharge nozzle 18 (nozzle region R).

17a to 17c recording head 18 ejection nozzle 20 hole 22 ink 22a purge ink 35a to 35c wiper 73 water repellent film 100 inkjet recording apparatus F ink ejection surface R nozzle area S paper (recording medium)
T nozzle row

Claims (6)

A recording head having an ink ejection surface including a nozzle region in which a plurality of ejection nozzles that eject ink onto a recording medium are opened,
A water repellent film is provided on the ink ejection surface,
The nozzle region is provided with a plurality of nozzle rows in which a plurality of the discharge nozzles are linearly arranged along a wiping direction that is a direction in which the wiper wipes the purge ink forcedly pushed out from the discharge nozzles,
On the ink ejection surface, holes having a hole diameter of 10 μm or more and 30 μm or less are formed on the same straight line as the nozzle row and upstream of the nozzle row in the wiping direction.
The hole is
Three or more nozzles are provided for each nozzle row,
A recording head, wherein each of the nozzle rows is disposed at a position within 30 mm from the most upstream discharge nozzle in the wiping direction.   The recording head according to claim 1, wherein a hole diameter of the hole is substantially the same as a nozzle diameter of the discharge nozzle.   The recording head according to claim 1, wherein two or more holes are arranged at a position within 10 mm from the most upstream discharge nozzle for each nozzle row.   4. The recording head according to claim 3, wherein all of the holes are arranged at positions within 10 mm from the most upstream discharge nozzle with respect to each nozzle row. 5.   5. The recording head according to claim 1, wherein the holes are arranged at substantially equal pitches from the most upstream discharge nozzle with respect to each nozzle row.   An ink jet recording apparatus comprising the recording head according to claim 1.

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