JP2010260311A - Inkjet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet head which prevents the deterioration of discharge characteristics in a nozzle face. <P>SOLUTION: The inkjet head includes a nozzle plate having a plurality of nozzles for discharging ink, a mask plate installed in a position where it does not protrude rather than the ink discharge face in the nozzle plate in the ink discharge direction, and a frame attached between the nozzle plate and the mask plate for deciding the mutual positional relationship. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink ejection characteristic technique in a nozzle plate of an inkjet head.

  2. Description of the Related Art Conventionally, a mask plate is provided on a nozzle plate in order to prevent contamination of the surrounding area with ink ejected from nozzle holes of an inkjet head used in an inkjet printer.

  The mask plate is attached so as to be in contact with the surface of the nozzle plate and has a structure protruding in the ink ejection direction from the surface of the nozzle plate (FIG. 4 of Patent Document 1, Patent Document 2, and Patent Document 3).

  As a method for removing ink adhering to the nozzle plate, a method of wiping with a wipe material before adhering ink adheres is known (FIG. 3 of Patent Document 1). As another method for removing ink adhering to the nozzle plate, a method based on partial suction maintenance is known (FIG. 2 of Patent Document 4).

  However, in the configurations of Patent Document 1, Patent Document 2, and Patent Document 3, a step portion is formed at the boundary between the nozzle plate and the mask plate. Regardless of the ink removing method using the wipe material or the ink removing method using the partial suction maintenance, the ink remains on the nozzle plate side at the step portion. Over time, the properties of the ink change and cause various problems. For example, ink adheres to the surface of the nozzle plate and cannot be removed even if wiped or partially sucked. As a result, the ink repellency on the surface of the nozzle plate is deteriorated, and the print quality is deteriorated.

  Further, normally, ink mist adheres and accumulates on the inkjet head. The ink mist is various, such as a rebound from the paper or a satellite. If the ink mist adheres to an electronic member or the like, it causes a failure of the ink jet head. When the gap between the surface of the nozzle plate and the paper is narrow, the paper may come into contact with the surface of the nozzle plate, damaging the surface of the nozzle plate and deteriorating the print quality.

  Further, in the conventional inkjet head, the mask plate is fixed so as to contact the nozzle plate. As a fixing method, an adhesive is common. As a material of the nozzle plate, a polyimide film is generally used. Since the polyimide film has a large insulation resistance, the mask plate in contact with the polyimide film cannot be grounded. For this reason, ink mist, paper dust, and the like are likely to adhere to the mask plate. These are factors that deteriorate the print quality of the inkjet head. In order to connect the mask plate to the ground, a separate part is required, which complicates the structure of the inkjet head.

  An object of the present invention is to provide an ink jet head that prevents deterioration of ink ejection characteristics in a nozzle plate.

  In order to solve the above-described problems, the present invention is provided with a nozzle plate having a plurality of nozzles for discharging ink, and a position that does not protrude in the ink discharge direction from the ink discharge surface of the nozzle plate. A mask plate, and a frame attached between the nozzle plate and the mask plate and determining a mutual positional relationship.

  The present invention has an effect of preventing deterioration of ink ejection characteristics in the nozzle plate.

1 is a schematic view of an inkjet recording apparatus 1 according to an embodiment of the present invention. 1 is a perspective view of an inkjet head 2 according to an embodiment of the present invention. It is a front view of the inkjet head 2 which concerns on embodiment of this invention. It is sectional drawing of the inkjet head 2 which concerns on embodiment of this invention. It is sectional drawing of the inkjet head 2 which concerns on embodiment of this invention which expands and shows the a part shown in FIG. It is a perspective view before the mask plate 10 which concerns on embodiment of this invention is assembled | attached to the frame 15. FIG. It is the figure seen from the nozzle plate 20 side after attaching the mask plate 10 which concerns on embodiment of this invention to the frame 15. FIG. It is sectional drawing of the inkjet head 2 for demonstrating the wipe maintenance with respect to the inkjet head 2 which concerns on embodiment of this invention. It is sectional drawing of the inkjet head 2 for demonstrating the wipe maintenance with respect to the inkjet head 2 which concerns on embodiment of this invention. It is sectional drawing which shows the inkjet head 2 before and behind the wipe by the wipe material 40 which concerns on embodiment of this invention. It is sectional drawing of the inkjet head 2 for demonstrating the partial suction maintenance with respect to the inkjet head 2 which concerns on embodiment of this invention. It is sectional drawing of the inkjet head 2 at the time of attaching the capping member 55 to the inkjet head 2 which concerns on embodiment of this invention. It is sectional drawing of the inkjet head 2 at the time of attaching the partial suction member 70 to the inkjet head 2 which concerns on embodiment of this invention.

  Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an inkjet recording apparatus 1 according to an embodiment of the present invention. The ink jet recording apparatus 1 according to the present embodiment performs color printing on a sheet that is a recording medium. As the paper, for example, plain paper, coated paper, OHP sheet or the like can be used.

  In the casing 114 of the ink jet recording apparatus 1, paper from the manual feed tray 104 or the paper cassette 105 to the paper discharge tray 111 or the paper discharge tray 112 via the printing unit 100 constituted by the drum 102 and the printing unit 103. A path P is provided.

  The manual feed tray 104 and the paper cassette 105 are provided with a paper feed mechanism 106 that separates the sheets stacked on the manual feed tray 104 and the paper cassette 105 one by one and supplies them to the paper path P. In the paper path P, the paper transport mechanism 113 that transports the paper from the manual feed tray 104 or the paper cassette 105 to the paper discharge mechanism 107 or the paper on which printing has been performed in the printing unit 100 is discharged. A paper discharge mechanism 107 is provided.

  The printing unit 100 performs printing based on the printing data by the printing unit 103 while rotating at a predetermined speed while the sheet is carried on the outer periphery of the drum 102. The printing unit 103 includes four nozzle units 120C (cyan), 120Y (yellow), 120M (magenta), and 120B (black). Each nozzle unit 120C, 120Y, 120M, and 120B includes an inkjet head 2 that selectively ejects ink from a plurality of nozzles 21 to be described later (see, for example, FIG. 4).

  The printing unit 103 is disposed on the upper side of the drum 102 such that a nozzle 21 provided in the inkjet head 2 described later faces the drum 102 from above. In the paper path P, when the paper feed mechanism 104 side is the upstream side and the paper discharge mechanism 107 side is the downstream side, the nozzle units 120C, 120Y, 120M, and 120B are 120C (cyan) and 120Y (yellow) in order from the upstream side. , 120M (magenta), 120B (black).

  In each nozzle unit 120C, 120Y, 120M, and 120B, a plurality of inkjet heads are arranged in the X-axis direction of the drum. Each nozzle unit 120 </ b> C, 120 </ b> Y, 120 </ b> M, 120 </ b> B is arranged such that the arrangement direction of nozzles 21 provided in the inkjet head 2 described later is parallel to the axial direction of the drum 102.

  Next, the structure of the inkjet head 2 according to this embodiment will be described. FIG. 2 is a perspective view of the inkjet head 2 according to the present embodiment. FIG. 3 is a front view of the inkjet head 2 according to the present embodiment. 4 is a cross-sectional view of the inkjet head 2 according to the present embodiment taken along the line XX ′ in FIG. In the inkjet head 2 according to the present embodiment, the position of the mask plate is determined so as to prevent ink mist from adhering to an electronic member or the like, and paper from coming into contact with the nozzle plate 20 surface and damaging the nozzle plate 20 surface. is doing.

  As shown in FIGS. 2 and 3, the arrow A direction is a direction in which ink droplets are ejected from the inkjet head 2. As shown in FIG. 2, the inkjet head 2 is provided with a nozzle plate 20 and a mask plate 10 facing the drum 102.

  As shown in FIG. 4, a plurality of nozzles 21 are formed on the nozzle plate 20. The inkjet head 2 is assembled with the nozzle plate 20 and the mask plate 10 through the frame 15 over the whole. FIG. 5 is a cross-sectional view of the inkjet head 2 showing an enlarged portion a shown in FIG.

  The frame 15 has an L-shaped cross section in which a cutout portion 15 </ b> B is provided on the ink discharge direction A side from the nozzle plate 20. The mask plate 10 is attached to the notch 15 </ b> B provided in the frame 15. A nozzle plate 20 is attached to the step portion 15A excluding the cutout portion 15B from the frame 15. The mask plate 10 is attached so as to be recessed on the side opposite to the ink ejection direction A at a distance between the nozzle plate 20 and L1 via the frame 15.

  When the distance between the nozzle plate 20 and the mask plate 10 is L1, the material thickness of the mask plate 10 is T1, the material thickness of the nozzle plate 20 is T2, and the height of the step portion 15A of the frame 15 is T3, L1 = ( The relationship T2 + T3) −T1> = 0 holds.

  Next, assembly of the mask plate 10 and the frame 15 to which the nozzle plate 20 is attached will be described. FIG. 6 is a perspective view before the mask plate 10 is assembled to the frame 15 (the frame 15 to which the nozzle plate 20 is attached). FIG. 7 is a view as seen from the nozzle plate 20 side after the mask plate 10 is assembled to the frame 15 (the frame 15 to which the nozzle plate 20 is attached).

  The mask plate 10 has an opening 10 </ b> B along the arrangement direction of the nozzles 21 in the nozzle plate 20 on the side to be joined to the frame 15. Further, the mask plate 10 has a protrusion 10C protruding in the entire circumferential direction toward the inside of the opening 10B. The protrusions 10 </ b> C may be provided at a predetermined interval so as to have an uneven shape, not the entire circumferential direction. The frame 15 is attached to the nozzle plate 20. The frame 15 is attached as shown in FIG. 5 by inserting the side provided with the step 15A toward the side provided with the projection 10C through the inside of the mask plate 10 and determining the position of the mask plate 10. .

  As shown in FIG. 7, the inner edge of the protrusion 10C of the mask plate 10 is just in contact with the step portion 15A of the frame 15, and the protrusion 10C is fitted with the notch portion 15B. The protrusion 10C and the step portion 15A (or the cutout portion 15B) function as positioning of the mask plate 10 and the nozzle plate 20.

  When the mask plate 10 is attached to the nozzle plate 20 via the frame 15, the relative positional relationship between the mask plate 10 and the nozzle plate 20 is always constant. As a result, the relative positional relationship between the mask plate 10 and the nozzle 21 is always constant. Therefore, by fitting the step portion 15A of the frame 15 with the projection 10C of the mask plate 10, the mask plate 10 can be easily and accurately assembled to the frame 15 without using an expensive jig.

  FIG. 8 is a cross-sectional view taken along the line XX ′ in FIG. 3 for explaining the wipe maintenance for the inkjet head 2 according to the present embodiment. The nozzles 21 that eject ink are perforated using the frame 15 as a reference. When the positioning accuracy between the mask plate 10 and the nozzle plate 20 is improved, as a result, the positioning accuracy between the mask plate 10 and the nozzle 21 is also improved.

  Here, how the conventional problem is solved by the inkjet head 2 having the above-described structure will be described below. FIG. 8 shows the adhered ink 50 formed by ink mist that adheres and accumulates on the surface of the nozzle plate 20 when the ink droplets 30 are ejected from the nozzles 21 onto the paper. The adhesion ink 50 changes its characteristics with time and causes various problems to the inkjet head 2.

  For example, the adhered ink 50 adheres to the surface of the nozzle plate 20 and cannot be removed even if the wipe material 40 is wiped. Therefore, the adhering ink 50 deteriorates the ink repellency on the surface of the nozzle plate 20 and deteriorates the printing quality.

  Next, the wipe maintenance for the inkjet head 2 according to the present embodiment will be specifically described. FIG. 9 is a cross-sectional view taken along the line XX ′ in FIG. 3 for explaining the wipe maintenance for the inkjet head 2 according to the present embodiment.

  The wipe material 40 wipes the ink 50 adhering to the surface of the nozzle plate 20 from one end side to the other end side while moving in the direction of arrow B in FIG. FIG. 10 is a cross-sectional view showing the inkjet head 2 before and after wiping with the wiping material 40.

  FIG. 10A is a cross-sectional view of the inkjet head 2 at the start of wiping with the wiping material 40, showing the portion b (near the frame 15) in FIG. 9 in an enlarged manner. FIG. 10B is a cross-sectional view of the inkjet head 2 after wiping with the wiping material 40 showing the portion b of FIG. 9 in an enlarged manner. FIG. 10C is a cross-sectional view of the inkjet head 2 immediately before the end of wiping with the wiping material 40, showing an enlarged portion c (near the frame 15) of FIG. 9. FIG. 10D is a cross-sectional view of the ink-jet head 2 after wiping with the wiping material 40 showing the portion c of FIG. 9 in an enlarged manner.

  As shown in FIG. 10A, first, the wipe member 40 rides on the nozzle surface 20 </ b> A of the nozzle plate 20 while wiping the mask surface 10 </ b> A of the mask plate 10, and wipes the adhered ink 50 on the nozzle plate 20. Adhering ink 50 wiped when the wipe material 40 runs from the mask surface 10 </ b> A to the nozzle surface 20 </ b> A is scraped off by the step portion 15 </ b> A at the boundary between the mask plate 10 and the nozzle plate 20. Therefore, after the wipe member 40 wipes the portion b in FIG. 9, the ink 52 remains on the mask surface 10A as shown in FIG. 10B. Since the ink 52 remaining on the mask surface 10A does not remain on the nozzle surface 20A, the characteristics of the nozzle plate 20 are not deteriorated and the print quality is not affected.

  From the state shown in FIG. 10A to the state shown in FIG. 10C, the wipe member 40 moves to the position of the mask plate surface 10A along the arrow B direction in FIG. 9 while further wiping the nozzle surface 20A. 9 is a step 15A at the boundary between the mask plate 10 and the nozzle plate 20. The mask plate 10 has a shape that is lower than the nozzle plate 20 along the extending direction of the tip of the wipe material 40. Therefore, after the wipe material 40 wipes the portion c of FIG. 9, the wiped attached ink 51 is not scraped off by the step portion 15A of the portion c as shown in FIG. 10 (d). The ink 52 does not remain on the nozzle surface 20A and the mask surface 10A.

  According to the present embodiment, the wipe material 40 can be uniformly brought into contact with the nozzle plate 20. Since the ink 52 does not remain on the nozzle plate 20, the ink repellency of the nozzle plate 20 does not deteriorate. As a result, stable printing by the inkjet head 2 becomes possible. 8 and 9. FIG. 10 is an embodiment in which the wipe member 40 moves and wipes in the arrow B direction with respect to the XX ′ cross section in FIG. 3. The wipe direction of the wipe member 40 may be a direction orthogonal to the arrow B direction.

  FIG. 11 is a cross-sectional view taken along the line XX ′ in FIG. 3 for explaining the partial suction maintenance for the inkjet head 2 according to the present embodiment. Here, a partial suction member 60 is provided instead of the wipe member 40 of the inkjet recording apparatus 1. The partial suction member 60 sucks the attached ink 50 from the tip of the suction port 61 by a negative pressure chamber 62 that applies a negative pressure. The partial suction member 60 sucks and removes the adhering ink 50 along the arrow D direction while moving in the arrow C direction while maintaining a gap with the nozzle surface 20A. The mask surface 10A does not protrude in the ink ejection direction from the nozzle surface 20A. When the partial suction member 60 moves along the arrow C direction, the ink 50 attached to the surface of the partial suction member 60 is scraped off by the step portion 15A (the portion d in FIG. 11) between the nozzle surface 20A and the mask plate surface 10A. It will never be done. The ink 50 attached to the surface of the partial suction member 60 moves to the mask plate surface 10A side. The ink 50 does not remain on the nozzle plate 20 side of the step portion 15A (the portion d in FIG. 11) between the nozzle surface 20A and the mask plate surface 10A. 11 is an embodiment in which the partial suction member 60 moves in the direction of arrow C with respect to the XX ′ cross section in FIG. 3. The movement direction of the partial suction member 60 may be a direction orthogonal to the direction of arrow C. .

  Next, another effect when the relationship between the mask plate 10 and the nozzle plate 20 is positioned by the frame 15 will be described. In the inkjet head 2 according to the present embodiment, the mask plate 10 is not in contact with the nozzle plate 20 as shown in FIGS. The mask plate 10 and the nozzle plate 20 are in contact with the frame 15, respectively.

  The frame 15 is formed of a conductive member or a member coated with a conductive film. Therefore, the mask plate 10 can be grounded via the frame 15. By connecting the mask plate 10 to the ground, it is possible to prevent dust, paper powder, ink mist, and the like from adhering to the mask plate 10 and to perform stable printing by the inkjet head 2. Since the inkjet head 2 according to the present embodiment does not require a separate part for ground connection, the structure can be simplified.

  Next, still another effect when the relationship between the mask plate 10 and the nozzle plate 20 is positioned by the frame 15 will be described. 12 is a cross-sectional view taken along the line XX ′ in FIG. 3 when the capping member 55 is attached to the nozzle plate 20 side of the inkjet head 2 according to the present embodiment. The capping member 55 is attached to the mask plate 10. The capping member 55 blocks the nozzle surface 20A of the nozzle plate 20 from outside air, thereby preventing the nozzle plate 20 from being protected, ink drying, and the like. For this reason, it is necessary to keep the accuracy of attaching the capping member 55 to the nozzle plate 20 good.

  According to the present embodiment, as described above, the relative positional relationship between the mask plate 10 and the nozzle 21 is always constant. Therefore, the positioning of the capping member 55 and the nozzle 21 is facilitated only by attaching the capping member 55 to the outer periphery of the mask plate 10. According to the present embodiment, when the capping member 55 is attached to the inkjet head 2, no adjustment for alignment is required, and the structure can be simplified.

  FIG. 13 is a cross-sectional view taken along the line XX ′ in FIG. 3 when the partial suction member 70 is attached to the nozzle plate 20 side of the inkjet head 2 according to the present embodiment. The partial suction member 70 is provided with a plurality of suction ports 71.

  When the plurality of suction ports 71 are pressed against the entire nozzle surface 20 </ b> A, the partial suction member 70 sucks the attached ink 50 on the nozzle surface 20 </ b> A from the tips of the plurality of suction ports 71 by the negative pressure chamber 72. When the partial suction member 70 is attached to the inkjet head 2, it is optimal that the suction port 71 is located at a position that does not face the nozzle 21 in the nozzle plate 20.

  As described above, the partial suction member 70 and the nozzle 21 can be easily aligned by simply attaching the partial suction member 70 to the outer periphery of the mask plate 10. According to this embodiment, when the partial suction member 70 is attached to the inkjet head 2, no adjustment for alignment is required, and the structure can be simplified.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet recording apparatus, 2 ... Inkjet head, 10 ... Mask plate, 10A ... Mask surface, 10B ... Opening part, 10C ... Projection, 15 ... Frame, 15A ... Step part, 20 ... Nozzle plate, 20A ... Nozzle surface, 21 ... Nozzle, 40 ... Wipe material, 60 ... Partial suction member, 70 ... Partial suction member, 120C ... Nozzle unit, 120Y ... Nozzle unit, 120M ... Nozzle unit, 120B ... Nozzle unit.

Japanese Patent Laid-Open No. 2003-341079 JP 2000-190513 A JP 2005-349687 A JP 2001-199086 A

Claims (4)

A nozzle plate having a plurality of nozzles for ejecting ink;
A mask plate provided at a position that does not protrude in the ink ejection direction from the ink ejection surface of the nozzle plate;
A frame attached between the nozzle plate and the mask plate and determining a relative positional relationship with each other;
An ink jet head comprising: The mask plate has an opening along the nozzle arrangement direction of the nozzle plate and a protrusion protruding toward the opening, and the frame discharges the ink at a position in contact with the mask plate. A notch portion recessed in a direction opposite to the direction, and a step portion having a predetermined height in the ink ejection direction constituted by the notch portion,
The inkjet head according to claim 1, wherein the protrusion fits with the notch and the step.   With respect to the ink ejection direction, the distance between the surface of the nozzle plate and the surface of the mask plate is L1, the thickness of the mask plate is T1, the thickness of the nozzle plate is T2, and the height of the step portion 3. The inkjet head according to claim 2, wherein a relationship of L1 = (T2 + T3) -T1> = 0 is established, where T3 is T3.   2. The ink jet head according to claim 1, wherein at least a surface of the frame is made of a conductive material, and the mask plate is grounded through the frame.

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