JP2012101379A - Liquid ejecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the distance of a landing position of a liquid ejected from a nozzle of different nozzle array with simple constitution.SOLUTION: A recording head 24 moves relatively to an X direction with respect to a recording paper 200. A first nozzle array L1 including a plurality of nozzles N arranged in a Y direction, and a second nozzle array L2 in which two or more nozzles N whose positions in the Y direction are different from those of respective nozzles N of the first nozzle array L1 are arranged in the Y direction, are formed parallel with the discharge face 26 of the recording head 24 at an interval of the distance d of the X direction. The first and second nozzles N1 and N2 are formed in the dimensions different from each other so that the intercentral distance between the dot D1 formed on the recording paper 200 by the ink ejected from the first nozzle N1 of the first nozzle array L1 and the dot D2 formed on the paper 200 by the ink ejected from the second nozzle N2 of the second nozzle array L2, is shorter than the distance d.

Description

  The present invention relates to a technique for ejecting a liquid such as ink.

  As shown in FIG. 12, a liquid ejecting apparatus (for example, an ink jet printing apparatus) in which a first nozzle array 91 and a second nozzle array 92 are arranged in parallel in the X direction (main scanning direction) has been proposed. ing. Each of the first nozzle row 91 and the second nozzle row 92 includes a plurality of nozzles 94 arranged along the Y direction (sub-scanning direction) intersecting the X direction. The first nozzle row 91 and the second nozzle row 92 differ in the position of each nozzle 94 in the Y direction.

  Patent Document 1 discloses a technique for matching the positions in the X direction of dots formed on the landing target (for example, recording paper) with the liquid ejected from each nozzle 94 in the first nozzle array 91 and the second nozzle array 92. It is disclosed. Specifically, among the plurality of ejection pulses of the drive signal, an ejection pulse that is actually applied to the liquid ejection is individually selected for the first nozzle row 91 and the second nozzle row 92, and the time point of the liquid ejection is set to the first time. By making the first nozzle row 91 and the second nozzle row 92 different, the positions of the dots formed by the nozzles 94 in the X direction are matched.

JP 2000-343729 A

  However, in the technique of Patent Document 1, it is necessary to match the time points of the plurality of injection pulses of the drive signal and the time points of selecting each of the injection pulses (the time point of latching data for selecting the injection pulse) with high accuracy on the time axis. When an error occurs between the two nozzles, the time point at which the liquid is ejected by the nozzles of the first nozzle row 91 and the second nozzle row 92 changes from the target time point, and an error occurs at the position of each dot. There is a problem. In view of the above circumstances, an object of the present invention is to reduce the distance between landing positions of liquid ejected from each nozzle of a plurality of nozzle arrays with a simple configuration.

  Means employed by the present invention to solve the above problems will be described. In order to facilitate the understanding of the present invention, in the following description, the correspondence between the elements of the present invention and the elements of the embodiments described later will be indicated in parentheses, but the scope of the present invention will be exemplified in the embodiments. It is not intended to be limited.

  In the liquid ejecting apparatus according to the aspect of the invention, the first nozzle row (for example, the first nozzle row L1) including a plurality of nozzles arranged in the first direction, and each nozzle in the first nozzle row at each position in the first direction. A second nozzle row (for example, the second nozzle row L2) including a plurality of nozzles arranged in the first direction so as to be different from each other is spaced by a predetermined distance (for example, distance d) in the second direction intersecting the first direction. A liquid ejecting section (for example, the recording head 24) that moves relative to the landing target (for example, the recording paper 200) formed by the liquid ejected from each nozzle in the second direction is provided. A first dot (for example, dot D1) formed on the landing target with the liquid ejected from one nozzle, and a second dot (for example, dot D2) formed on the landing target with the liquid ejected from the second nozzle of the second nozzle. ) In the second direction with The first nozzle and the second nozzle are formed in different dimensions so that the distance between the centers is less than a predetermined distance.

  In the above configuration, the first nozzle and the second dot are arranged such that the distance between the centers of the first dot and the second dot in the second direction is less than the distance between the centers of the first nozzle and the second nozzle in the second direction. The dimensions of each of the two nozzles are selected. For example, in a configuration in which the first nozzle row is positioned in front of the second nozzle row in the traveling direction of the liquid ejecting unit with respect to the landing target, the speed of the liquid ejected from the first nozzle is the liquid ejected from the second nozzle. The size of each of the first nozzle and the second nozzle is selected so as to exceed the speed. Therefore, the difference in the position in the second direction between the landing position (first dot) of the liquid ejected from the first nozzle and the landing position (second dot) of the liquid ejected from the second nozzle is reduced with a simple configuration. Is possible.

  In the above description, only the first nozzle row and the second nozzle row are mentioned, but the total number of nozzle rows formed in the liquid ejecting unit is arbitrary in the present invention. That is, even in a configuration in which three or more nozzle rows are formed in the liquid ejecting unit, a configuration that satisfies the above-described requirements when two of the three rows are grasped as the first nozzle row and the second nozzle row, Naturally, it is included in the scope of the present invention.

  In a preferred aspect of the present invention, the in-pipe cross-sectional area differs between the first nozzle and the second nozzle. For example, in a configuration in which the first nozzle row is positioned in front of the second nozzle row in the traveling direction of the liquid ejecting unit with respect to the landing target, the cross-sectional area of the first nozzle is less than the cross-sectional area of the second nozzle. The nozzle dimensions are selected. In the above configuration, the distance between the centers of the first dot and the second dot in the second direction can be reduced according to the cross-sectional area of each nozzle in the tube.

  In a preferred aspect of the present invention, the first dot formed by the liquid ejected from the first nozzle and the second dot formed by the liquid ejected from the second nozzle closest to the first nozzle are mutually connected. The dimensions of each of the first nozzle and the second nozzle are selected so as to overlap or contact each other. In the above aspect, it is possible to make the first dots and the second dots continuous with each other by a simple method of appropriately selecting the dimensions of the first nozzle and the second nozzle.

  In a preferred aspect of the present invention, the dimensions of the first nozzle and the second nozzle are selected so that the first dot and the second dot have the same center position in the second direction. In the above aspect, it is possible to arrange the first dots and the second dots in the first direction by a simple method of appropriately selecting the dimensions of the first nozzle and the second nozzle.

  In a preferred aspect of the present invention, the inertance of the first nozzle and the inertance of the second nozzle are the same. In the above aspect, since the inertance is set to be equal between the first nozzle and the second nozzle, the difference between the liquid discharge amount from the first nozzle and the liquid discharge amount from the second nozzle is effectively reduced. There is an advantage that you can. In addition, the specific example of the above aspect is later mentioned as 2nd Embodiment, for example.

It is a partial schematic diagram of the printing apparatus according to the first embodiment of the present invention. 3 is a plan view of an ejection surface of a recording head. FIG. 3 is a cross-sectional view of a recording head. It is a block diagram of the electrical configuration of the printing apparatus. It is a wave form diagram of a drive signal. FIG. 2 is a block diagram of an electrical configuration of a recording head. It is explanatory drawing of the flight path | route of the ink ejected from each nozzle. It is explanatory drawing of the position (dot position) where the ink ejected from each nozzle lands. It is a schematic diagram of the straight pipe line which approximates each nozzle in 2nd Embodiment. FIG. 10 is a schematic diagram of an ejection surface of a recording head in a modified example. FIG. 10 is a schematic diagram of a recording head in a modified example. It is a schematic diagram which shows the arrangement | sequence of the conventional nozzle.

<A: First Embodiment>
FIG. 1 is a partial schematic view of an ink jet printing apparatus 100 according to a first embodiment of the present invention. The printing apparatus 100 is a liquid ejecting apparatus that ejects fine droplet-shaped ink onto the recording paper 200, and includes a carriage 12, a moving mechanism 14, and a sheet conveying mechanism 16.

  An ink cartridge 22 and a recording head 24 are mounted on the carriage 12. The ink cartridge 22 is a container that stores ink (liquid) ejected onto the recording paper 200. The recording head 24 functions as a liquid ejecting unit that ejects ink stored in the ink cartridge 22 onto the recording paper 200. A configuration in which the ink cartridge 22 is fixed to a housing (not shown) of the printing apparatus 100 and ink is supplied to the recording head 24 can also be employed.

  The moving mechanism 14 reciprocates the carriage 12 along the guide shaft 122 in the X direction (main scanning direction corresponding to the width direction of the recording paper 200). The position of the carriage 12 is detected by a detector (not shown) such as a linear encoder and used for controlling the moving mechanism 14. The paper transport mechanism 16 moves the recording paper 200 in the Y direction (sub-scanning direction) in parallel with the reciprocation of the carriage 12. A desired image is recorded (printed) on the recording paper 200 by the recording head 24 ejecting ink onto the recording paper 200 during the reciprocation of the carriage 12.

  FIG. 2 is a plan view of the ejection surface 26 of the recording head 24 that faces the recording paper 200. As shown in FIG. 2, a plurality of nozzle groups 28 corresponding to different ink colors (black (K), yellow (Y), magenta (M), cyan (C)) are formed on the ejection surface 26 of the recording head 24. (28K, 28Y, 28M, 28C) are formed.

  Each of the plurality of nozzle groups 28 includes a first nozzle row L1 and a second nozzle row L2. Each of the first nozzle row L1 and the second nozzle row L2 is a set of a plurality of nozzles N arranged in the Y direction with a space therebetween. Each nozzle N is formed in a circular shape in plan view. Black (K) ink is ejected from each nozzle N of the nozzle group 28K. Similarly, yellow (Y) ink is ejected from each nozzle N of the nozzle group 28Y, magenta (M) ink is ejected from each nozzle N of the nozzle group 28M, and each nozzle N of the nozzle group 28C is ejected from each nozzle N. Cyan (C) ink is ejected.

  The first nozzle row L1 and the second nozzle row L2 are juxtaposed at a distance d in the X direction. Specifically, the Y-direction straight line (center line of the first nozzle row L1) a1 connecting the centers of the nozzles N of the first nozzle row L1 and the centers of the nozzles N of the second nozzle row L2 are connected. A straight line in the Y direction (center line of the second nozzle row L2) a2 extends in parallel with an interval d therebetween. Further, the positions in the Y direction of the nozzles N of the first nozzle row L1 and the nozzles N of the second nozzle row L2 are different. Specifically, the position in the Y direction of each nozzle N in the first nozzle row L1 and the position in the Y direction of each nozzle N in the second nozzle row L2 are the distances between the centers of the nozzles N adjacent in the Y direction. They are in a mutually shifted relationship in the Y direction by half of p (p / 2). That is, the plurality of nozzles N of each nozzle group 28 are arranged in two rows in a staggered manner.

  FIG. 3 is a sectional view of the recording head 24 (cross section perpendicular to the X direction). As shown in FIG. 3, the recording head 24 includes a vibration unit 42, a container 44, and a flow path unit 46. The vibration unit 42 includes a piezoelectric vibrator 422, a cable 424, and a fixed plate 426. The piezoelectric vibrator 422 is a longitudinal vibration type piezoelectric element in which piezoelectric materials and electrodes are alternately stacked, and vibrates according to a drive signal supplied via the cable 424. The vibration unit 42 is housed in the housing body 44 in a state where the fixed plate 426 to which the piezoelectric vibrator 422 is fixed is bonded to the inner wall surface of the housing body 44.

  The flow path unit 46 is a structure in which a flow path forming plate 466 is inserted in a gap between the substrates 462 and 464 facing each other. The surface of the substrate 462 opposite to the substrate 464 corresponds to the ejection surface 26 in FIG. The flow path forming plate 466 forms a space including the pressure chamber 50, the supply path 52, and the storage chamber 54 in the gap between the substrate 462 and the substrate 464. The pressure chamber 50 is individually partitioned by a partition for each vibration unit 42 and communicates with the storage chamber 54 via the supply path 52. Ink supplied from the ink cartridge 22 is stored in the storage chamber 54. Each nozzle N in FIG. 2 is formed on the substrate 462 so as to correspond to each pressure chamber 50. Each nozzle N is a through hole communicating with the pressure chamber 50. As can be understood from the above description, an ink flow path is formed from the storage chamber 54 to the outside via the supply path 52, the pressure chamber 50, and the nozzle N.

  The substrate 464 is a flat plate made of an elastic material. A diaphragm having an island portion 48 is formed in a region of the substrate 464 opposite to the pressure chamber 50. The distal end surface (free end) of the piezoelectric vibrator 422 is joined to the island portion 48. Therefore, when the piezoelectric vibrator 422 is vibrated by the supply of the drive signal, the substrate 464 is displaced via the island portion 48, whereby the volume of the pressure chamber 50 is changed and the pressure of the ink in the pressure chamber 50 is changed. That is, the piezoelectric vibrator 422 functions as a pressure generating element that varies the pressure in the pressure chamber 50. Ink can be ejected from the nozzles N in accordance with the pressure fluctuations in the pressure chamber 50 described above.

  FIG. 4 is a block diagram of an electrical configuration of the printing apparatus 100. As illustrated in FIG. 4, the printing apparatus 100 includes a control device 102 and a print processing unit (print engine) 104. The control device 102 is an element that controls the entire printing apparatus 100, and includes a control unit 60, a storage unit 62, a drive signal generation unit 64, an external I / F (interface) 66, and an internal I / F 68. Print data DP indicating an image to be printed on the recording paper 200 is supplied from an external device (for example, a host computer) 300 to the external I / F 66, and the print processing unit 104 is connected to the internal I / F 68. The print processing unit 104 is an element that records an image on the recording paper 200 under the control of the control device 102, and includes the recording head 24, the moving mechanism 14, and the paper transport mechanism 16 described above.

  The storage unit 62 in FIG. 4 includes a ROM that stores a control program and the like, and a RAM that temporarily stores various data necessary for image printing. The control unit 60 comprehensively controls each element (for example, the print processing unit 104) of the printing apparatus 100 by executing the control program stored in the storage unit 62. For example, the control unit 60 causes the recording head 24 to perform an operation of recording an image corresponding to the print data DP on the recording paper 200 by ejecting ink onto the recording paper 200. Specifically, the control unit 60 uses the print data DP supplied from the external device 300 to the external I / F 66 to control data for instructing ink ejection / non-ejection (fine vibration) in the pressure chamber 50. Generate DC.

  The drive signal generator 64 generates a drive signal COM. The drive signal COM is a periodic signal that drives each piezoelectric vibrator 422. As shown in FIG. 5, within one cycle (recording cycle) of the drive signal COM, the ejection pulse PD for ejecting the ink in the pressure chamber 50 from the nozzle N and the ink in the pressure chamber 50 are not ejected from the nozzle N. A fine vibration pulse PS for applying a slight vibration to the pressure chamber 50 is arranged.

  FIG. 6 is a schematic diagram of an electrical configuration of the recording head 24. As shown in FIG. 6, the recording head 24 includes a plurality of drive circuits 32 corresponding to different pressure chambers 50. The drive signal COM generated by the drive signal generator 64 is commonly supplied to the plurality of drive circuits 32 via the internal I / F 68. The control data DC generated by the control unit 60 is supplied to each drive circuit 32 via the internal I / F 68.

  Each drive circuit 32 selects a section (injection pulse PD / microvibration pulse PS) corresponding to the control data DC supplied from the control unit 60 from the drive signal COM and supplies the selected section to the piezoelectric vibrator 422. Specifically, when the control data DC instructs ink ejection, the drive circuit 32 selects the ejection pulse PD of the drive signal COM and supplies it to the piezoelectric vibrator 422. Therefore, the ink in the pressure chamber 50 is ejected from the nozzle N. On the other hand, when the control data DC instructs non-ejection of ink, the drive circuit 32 selects the fine vibration pulse PS of the drive signal COM and supplies it to the piezoelectric vibrator 422. Therefore, a slight vibration is applied to the pressure chamber 50, and the ink in the pressure chamber 50 is appropriately jetted without being ejected.

  FIG. 7 is a schematic diagram showing how ink ejected from each nozzle N of the recording head 24 lands on the surface of the recording paper 200 by supplying the ejection pulse PD to the piezoelectric vibrator 422. In the following description, as shown in FIG. 7, any one nozzle N in the first nozzle row L1 of one nozzle group 28 (hereinafter referred to as “first nozzle N1” in particular), Attention is paid to the one nozzle N closest to the first nozzle N1 in the second nozzle row L2 of the nozzle group 28 (hereinafter, particularly referred to as “second nozzle N2”). However, the same relationship is established for each nozzle N in each of the plurality of nozzle groups 28 (28K, 28Y, 28M, 28C).

  As shown in FIG. 7, the ejection surface 26 of the recording head 24 and the surface of the recording paper 200 face each other with a gap G. The control unit 60 vibrates each of the piezoelectric vibrators 422 while moving the carriage 12 to which the recording head 24 is fixed relative to the recording paper 200 in the X direction at a speed VCR. Ink is simultaneously ejected from the nozzles N (N1, N2). The ink ejected from each nozzle N flies through the gap between the ejection surface 26 and the recording paper 200 and lands on the surface of the recording paper 200 to form dots (pixels).

  FIG. 8 is a schematic diagram showing a planar positional relationship between the dots D1 formed with the ink ejected from the first nozzle N1 and the dots D2 formed with the ink ejected from the second nozzle N2. Since the first nozzle N1 and the second nozzle N2 are separated from each other by a distance d in the X direction, the speed at which the ink ejected from each nozzle N flies toward the recording paper 200 (hereinafter referred to as “flight speed”) is the first. If the 1 nozzle N1 and the 2nd nozzle N2 are equivalent, the dot D1 formed with the ink ejected from the first nozzle N1 and the dot D2 formed with the ink ejected from the second nozzle N2 (broken line in FIG. 8) Are separated from each other with a distance d between the centers in the X direction. However, if the dots D1 and D2 are separated from each other on the recording paper 200 as described above, the quality of the image formed on the recording paper 200 is deteriorated.

  Therefore, in the first embodiment, the first nozzle N1 is ejected so that the distance in the X direction between the dots D1 and D2 on the surface of the recording paper 200 is less than the distance d between the first nozzle N1 and the second nozzle N2. The ink flying speed V1 and the ink flying speed V2 ejected from the second nozzle N2 are set to different speeds. That is, the flying speed V1 of the ink ejected from the first nozzle N1 located in front of the recording head 24 (carriage 12) in FIG. 7 was ejected from the second nozzle N2 located behind in the traveling direction. The ink flying speed V2 is exceeded (V1> V2). The flying speed V1 and the flying speed V2 are average speeds from ejection from each nozzle N (N1, N2) to landing on the recording paper 200.

  Specifically, as shown in FIG. 8, the flying speed V1 and the flying speed are set such that the center position x2 of the dot D2 in the X direction is limited to a predetermined range A including the center position x1 of the dot D1. The relationship with speed V2 is selected. The range A is a region between the position xL of the dot D1 from the X-direction position x1 to the one side in the X direction by a distance δ and the position xR from the position x1 to the other side in the X direction by a distance δ. is there. The distance δ defining the range A is selected so that the dots D1 and D2 overlap or contact each other in plan view. In the following, it is assumed that the dots D1 and D2 have a circular shape with the same diameter φ.

  As shown by a chain line in FIG. 8, when the dots D1 and D2 having the diameter φ are in contact (externally), the distance between the centers of the dots D1 and D2 matches the diameter φ. Now, the distance between the centers of the dots D1 and D2 in the Y direction (the distance (p / 2) between the centers of the first nozzle N1 and the second nozzle N2 in the Y direction) is the distance φ / according to the diameter φ. Assuming √2, the dot D1 and the dot D2 come into contact when the distance between the centers of the dot D1 and the dot D2 in the X direction is the distance φ / √2. Accordingly, the distance δ defining the range A is set to a distance φ / √2 corresponding to the diameter φ of the dots D1 and D2. That is, the flying speed V1 and the flying speed V2 are set so that the center position x2 of the dot D2 is included in the range A extending from the position x1 of the dot D1 in the X direction to both sides in the X direction by the distance φ / √2. .

  In order to specify a specific relationship between the flying speed V1 and the flying speed V2, the center position (ink landing position) x1 of the dot D1 formed by the first nozzle N1 and the dot D2 formed by the second nozzle N2 Consider the center position x2. As shown in FIG. 7, the position x1 and the position x2 are positions based on the position in the X direction of the second nozzle N2 when ink is ejected from each nozzle N (x = 0).

Since time (G / V1) elapses until the ink ejected from the first nozzle N1 flies at the flying speed V1 and lands on the recording paper 200, the ejected ink is flying (time (G / V1)). (Inside), the recording paper 200 moves relative to the recording head 24 in the X direction by a distance (G / V1) · VCR. Therefore, the position x1 of the dot D1 is expressed by the following formula (1).
x1 = (G / V1) ・ VCR + d (1)

Similarly, the recording paper 200 is relatively relative to the recording head 24 by a distance (G / V2) · VCR before the ink jetted from the second nozzle N2 and flying at the flying speed V2 (flying speed V2) is landed. Since it moves, the position x2 of the dot D2 is expressed by the following equation (2).
x2 = (G / V2) ・ VCR (2)

When the center position x2 of the dot D2 in the X direction is located at the position xL in FIG. 8 (x2 = x1−δ), the flying speed V2 is expressed by the following equation (3).
V2 = G · VCR / (x1−δ)
= G ・ VCR / {(G / V1) ・ VCR + d−δ} (3)

Similarly, when the center position x2 of the dot D2 in the X direction is located at the position xR in FIG. 8 (x2 = x1 + δ), the flying speed V2 is expressed by the following equation (4).
V2 = G · VCR / (x1 + δ)
= G ・ VCR / {(G / V1) ・ VCR + d + δ} (4)

From the formulas (3) and (4), the range of the flying speed V2 is expressed by the following formula (5).
G • VCR / {(G / V1) • VCR + d + δ} ≦ V2 ≦ G • VCR / {(G / V1) • VCR + d−δ} (5)

In a more preferred embodiment, as indicated by a solid line in FIG. 8, the center position x1 of the dot D1 and the center position x2 of the dot D2 in the X direction coincide. Therefore, the flying speed V2 is expressed by the following formula (6).
V2 = G ・ VCR / {(G / V1) ・ VCR + d} (6)

  The theoretical relationship between the flying speed V1 and the flying speed V2 is as described above. The flying speed V1 depends on the dimension (diameter) of the first nozzle N1, and the flying speed V2 depends on the dimension of the second nozzle N2. Therefore, in the first embodiment, the first nozzle N1 and the second nozzle N2 are in phase so that the flying speed V1 and the flying speed V2 satisfy the condition of the expression (5) (more preferably, the condition of the expression (6)). Formed in different dimensions. Specifically, in accordance with the speed VCR of the recording head 24, the distance G between the ejection surface 26 and the recording paper 200, and the distance d in the X direction between the first nozzle N1 and the second nozzle N2, Equation (5) The design values of the flying speed V1 and the flying speed V2 are calculated so as to satisfy the relationship of the formula (6), and the first nozzle N1 and the second nozzle N2 are set so that the actual flying speed V1 and the flying speed V2 become the designed values. A diameter is selected. The dimensions of the first nozzle N1 and the second nozzle N2 will be described in detail below.

The relationship between the flying speed V1 and the flying speed V2 (design value) set so as to satisfy the formula (5) or the formula (6) is expressed as the following formula (7) including a constant α (α> 0). To do. The constant α means a relative ratio of the flying speed V2 to the flying speed V1. Since the flying speed V2 is lower than the flying speed V1, the constant α is set to a positive number less than 1.
V2 = α ・ V1 (7)

On the other hand, each of the flight speed V1 and the flying speed V2, the flow rate of the ink passing through the tube cross-sectional area S1 of the first nozzle N1 (m ²⁾ and the tube cross-sectional area S2 of the second nozzle N2 and (m ²⁾ each nozzle N It is expressed by the following formula (8) including Q (m ³ / s). The flow rate Q is common to the first nozzle N1 and the second nozzle N2.
V1 = Q / S1, V2 = Q / S2 (8)
By substituting equation (8) into equation (7), the following equation (9) is derived. As understood from Equation (9), the in-tube cross-sectional area S1 of the first nozzle N1 is smaller than the in-tube cross-sectional area S2 of the second nozzle N2.
S1 = α ・ S2 (9)

Then, if the in-tube cross-sectional area S1 is defined by the radius r1 of the first nozzle N1 (S1 = π · r1 ² ) and the in-tube cross-sectional area S2 is defined by the radius r2 of the second nozzle N2 (S2 = π · r2 ² ), The following formula (10) is derived.
r1 = α1 ^{/ 2}・ r2 (10)
The radius r1 of the first nozzle N1 and the radius r2 of the second nozzle N2 are selected so as to satisfy the condition of Equation (10). As understood from Equation (10), the radius r1 of the first nozzle N1 is smaller than the radius r2 of the second nozzle N2.

  In the configuration in which the radius r1 and the radius r2 are selected so that the mathematical formula (10) is established for the flying speed V1 and the flying speed V2 that satisfy the mathematical formula (5), the center position x1 of the dot D1 in the X direction is The center (x2) of the dot D2 is located within the included range A. Further, in the configuration in which the radius r1 and the radius r2 are selected so that the mathematical expression (10) is established for the flying speed V1 and the flying speed V2 satisfying the mathematical expression (6), the position of the center of the dot D1 in the X direction is selected. x1 coincides with the center position x2 of the dot D2. That is, dots formed by ink ejected from each nozzle N in the nozzle group 28 are linearly arranged in the Y direction.

  As described above, in the first embodiment, the distance between the centers of the dots D1 and D2 in the X direction is less than the distance d in the X direction between the first nozzle N1 and the second nozzle N2. The flying speed V1 and the flying speed V2 are selected according to the dimensions (radius r1 and radius r2) of the first nozzle N1 and the second nozzle N2. Specifically, the dot D1 and the dot D2 contact or overlap each other in plan view (Equation (5)), and more preferably, the positions of the centers of the dots D1 and D2 in the X direction match (Equation (6) )), The first nozzle N1 and the second nozzle N2 are formed in different dimensions. Therefore, there is an advantage that the difference in the landing positions (dots) in the X direction of the ink ejected from the plurality of nozzles N in each nozzle group 28 can be reduced with a simple configuration.

  By the way, when a plurality of drops of ink flying from the nozzles N toward the recording paper 200 are excessively approached, the ink traveling direction is changed from the straight traveling direction to the mutual traveling direction due to the influence of the airflow between each approaching ink and the Coulomb force. There is a problem that the ink is inclined in a direction away from each other, resulting in an error in the landing position of each ink. The higher the resolution of the printed image (for example, when the resolution exceeds 600 dpi), the more the inclination of the ink traveling direction becomes obvious. According to the first embodiment, since the flying speed V1 of the ink ejected from the first nozzle N1 and the flying speed V2 of the ink ejected from the second nozzle N2 are different, the closer to the surface of the recording paper 200, the first The distance between the ink from the nozzle N1 and the ink from the second nozzle N2 increases. Therefore, there is also an advantage that the error of the landing position due to the excessive approach of the ink ejected from each of the first nozzle N1 and the second nozzle N2 can be reduced.

<B: Second Embodiment>
A second embodiment of the present invention will be described below. In addition, about the element which an effect | action and a function are equivalent to 1st Embodiment in each aspect illustrated below, each reference detailed in the above description is diverted and each detailed description is abbreviate | omitted suitably.

  According to the first embodiment in which the in-tube cross-sectional area S1 of the first nozzle N1 and the in-tube cross-sectional area S2 of the second nozzle N2 satisfy Equation (9) above, the positions of the dots D1 and D2 in the X direction are brought closer to each other. It is possible. However, the ink ejection efficiency differs between the first nozzle N1 and the second nozzle N2 only under the condition of the formula (9). As a result, the weight of the ink ejected from the pressure chamber 50 is different from that of the first nozzle N1. There is a possibility of a difference between the second nozzle N2. In consideration of the above circumstances, in the second embodiment, the inertance of the first nozzle N1 and the inertance of the second nozzle N2 are equal to each other in addition to the conditions of the first embodiment (formula (10)). Thus, the dimensions of the first nozzle N1 and the second nozzle N2 are selected.

As shown in FIG. 9, a straight pipe line (cylinder) that approximates each nozzle N of the recording head 24 is assumed. The first nozzle N1 is approximated by a straight pipe line having an in-pipe cross-sectional area S1 and a total length L1, and the second nozzle N2 is approximated by a straight pipe line having a cross-sectional area S2 and a total length L2. Accordingly, the inertance M1 of the first nozzle N1 and the inertance M2 of the second nozzle N2 are expressed by the following formula (11). The symbol ρ in Equation (11) means the ink density.
M1 = ρ · L1 / S1, M2 = ρ · L2 / S2 (11)

From the condition that the inertance M1 of the first nozzle N1 and the inertance M2 of the second nozzle N2 are equal, the following formula (12) is derived.
ρ ・ L1 / S1 ＝ ρ ・ L2 / S2 (12)
When the relationship of the above formula (9) is applied to the formula (12), the following formula (13) is derived.
L1 = α ・ L2 (13)

  The dimensions (full length L1 and full length L2) of the first nozzle N1 and the second nozzle N2 are selected so that the relationship of Expression (13) is established. Considering that the shape (and also inertance) in the pressure chamber 50 is common to the first nozzle N 1 and the second nozzle N 2, the total length L 1 of Equation (13) is substantially the first of the substrates 462. The total thickness L2 of the equation (13) is regarded as the same as the thickness of the portion of the substrate 462 where the second nozzle N2 is formed. That is, the plate thickness L1 of the portion where the first nozzle N1 is formed in the substrate 462 and the plate thickness L2 of the portion where the second nozzle N2 are formed have different dimensions so as to satisfy the relationship of Equation (13). Is set.

  In addition, although the method of making the board thickness of the board | substrate 462 differ by the site | part (plate thickness L1) of the 1st nozzle N1 and the site | part (plate thickness L2) of the 2nd nozzle N2, for example, each nozzle N is formed. A method of making the punch shape different between the first nozzle N1 and the second nozzle N2, and a method of making the etching degree for partially removing the substrate 462 in the plate thickness direction different between the first nozzle N1 and the second nozzle N2. Is preferred.

  In the second embodiment described above, the same effects as in the first embodiment are realized. In the second embodiment, the dimensions (L1, L2) of the first nozzle N1 and the second nozzle N2 are such that the inertance M1 of the first nozzle N1 and the inertance M2 of the second nozzle N2 are equal to each other. Is selected, it is possible to reduce (ideally match) the difference in the weight of the ink ejected from each of the first nozzle N1 and the second nozzle N2.

<C: Modification>
Each of the above forms can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined.

(1) Modification 1
In each of the above embodiments, the ink is simultaneously ejected from the first nozzle N1 and the second nozzle N2, but the time point at which the ink in the pressure chamber 50 is ejected is different between the first nozzle N1 and the second nozzle N2. Can also be employed. For example, a configuration in which ink is ejected from the second nozzle N2 when a predetermined time has elapsed from the ejection of ink by the first nozzle N1 is suitable. In addition, the structure for making the time of the ejection of the ink by each nozzle N different is arbitrary. As described above, by delaying the ejection of the ink from the second nozzle N2 with respect to the ejection from the first nozzle N1, the distance between the centers of the dots D1 and D2 in the X direction is the first nozzle N1 and the second. It is less than the distance d between the center with the nozzle N2. Therefore, the first nozzle N1 and the second nozzle N2 are compared with the configuration in which the positions of the dots D1 and D2 are made close to each other only by the configuration in which the dimensions of the first nozzle N1 and the second nozzle N2 are different. It is possible to reduce the difference in dimensions.

(2) Modification 2
In each of the above embodiments, the nozzle group 28 is constituted by two rows of the first nozzle row L1 and the second nozzle row L2, but the total number of nozzle rows L constituting each nozzle group 28 is arbitrary. As illustrated in FIG. 10, in a configuration in which each nozzle group 28 includes K nozzle rows L1 to LK (K is a natural number of 2 or more), each nozzle N is arranged between two nozzle rows L adjacent to each other. The center position in the Y direction is shifted in the Y direction by a distance (p / K). In the configuration of FIG. 10, the flying speed Vk of ink ejected from each nozzle N in the nozzle array Lk (k = 1 to K) located in front of the recording head 24 in the traveling direction of the K nozzle arrays L1 to LK. (V1>V2>...> VK), the dimensions (radius and total length) of each nozzle N are individually selected for each nozzle row Lk.

(3) Modification 3
In each of the above embodiments, the serial type printing apparatus 100 in which the carriage 12 on which the recording head 24 is mounted moves in the X direction (main scanning direction) is exemplified. However, as shown in FIG. The present invention can also be applied to a printing apparatus using a line-type recording head 24 in which nozzle groups 28 are formed so as to face the entire area. In FIG. 11, only one nozzle group 28 is shown for convenience, but a plurality of nozzle groups 28 (28K, 28Y, 28M, 28C) corresponding to different ink colors are actually formed.

  In the nozzle group 28 of the recording head 24 in FIG. 11, the first nozzle row L1 and the second nozzle row L2 composed of a plurality of nozzles N arranged in the X direction (width direction of the recording paper 200) are in the Y direction (recording). The sheet 200 is formed with an interval d in the conveyance direction of the paper 200. The position of each nozzle N in the X direction is different between the first nozzle row L1 and the second nozzle row L2. The recording head 24 is fixed, and an image is recorded on the recording paper 200 by ejecting ink from each nozzle N while transporting the recording paper 200 in the Y direction.

  Also in the configuration of FIG. 11, as in the first embodiment and the second embodiment, the recording paper 200 is positioned upstream in the conveyance direction (that is, forward in the relative movement direction of the recording head 24 with respect to the recording paper 200). The flying speed V1 of the ink ejected from each nozzle N of the first nozzle array L1 exceeds the flying speed V2 of the ink from each nozzle of the second nozzle array L2 located on the downstream side in the conveyance direction of the recording paper 200. Thus, the nozzles N are formed in different dimensions (radius and overall length) in the first nozzle row L1 and the second nozzle row L2.

  As understood from the above description, the present invention is preferably applied to a configuration in which the recording head 24 moves relative to the recording paper 200 (landing target), and the movement / fixation of the recording head 24 itself is performed according to the present invention. Is unquestionable. In the first embodiment and the second embodiment, the Y direction corresponds to the first direction of the present invention and the X direction corresponds to the second direction. In the configuration of FIG. 11, the X direction is the first direction of the present invention. And the Y direction corresponds to the second direction.

(4) Modification 4
In each of the above embodiments, the relationship between the flying speed V1 and the flying speed V2 (formula (5), formula (6)) is defined using the diameter φ of the dots (D1, D2). Replacement with R (dpi: dot per inch) is also possible. The diameter φ is expressed by the following formula (14) including the resolution R.
φ = (2.54 × 10 ² / R) × √2 (14)

Assuming that the distance δ in the equation (5) is the distance φ / √2 as described above, the following equation (15) is derived by substituting the equation (14) into the equation (5).
G · VCR / {(G / V1) · VCR + d + (/ 2.54 × 10 2 R)} ≦ V2 ≦ G · VCR / {(G / V1) · VCR + d- (2.54 × 10 2 / R)} ...... (15 )
The flying speed V1 and the flying speed V2 are determined according to the resolution R so that the relationship of Expression (15) is established.

(5) Modification 5
In each of the above embodiments, one system of drive signals COM is supplied to the recording head 24. However, a configuration in which a plurality of systems of drive signals are used to drive each piezoelectric vibrator 422 may be employed. Further, the waveform of each pulse (PD, PS) of the drive signal is arbitrary, and the fine vibration pulse PS is not limited to the trapezoidal pulse illustrated in FIG. 5, and for example, a rectangular pulse can be adopted. is there.

(6) Modification 6
In each of the above embodiments, the longitudinal vibration type piezoelectric vibrator 422 is illustrated, but the configuration of the element (pressure generating element) that changes the pressure in the pressure chamber 50 is not limited to the above examples. For example, a vibrating body such as a flexural vibration type piezoelectric vibrator or an electrostatic actuator can be used. Further, the pressure generating element is not limited to an element that gives mechanical vibration to the pressure chamber 50. For example, a heat generating element (heater) that changes the pressure in the pressure chamber 50 by generating bubbles by heating the pressure chamber 50 can be used as the pressure generating element. That is, the pressure generating element is included as an element for changing the pressure in the pressure chamber 50, and the method for changing the pressure (piezo method / thermal method) and the configuration are not limited.

(7) Modification 7
The printing apparatus 100 of each of the above forms can be employed in various devices such as a plotter, a facsimile machine, and a copier. However, the application of the liquid ejecting apparatus of the present invention is not limited to image printing. For example, a liquid ejecting apparatus that ejects a solution of each color material is used as a manufacturing apparatus that forms a color filter of a liquid crystal display device. In addition, a liquid ejecting apparatus that ejects a liquid conductive material is used as an electrode manufacturing apparatus that forms electrodes of a display device such as an organic EL (Electroluminescence) display device or a field emission display (FED). The A liquid ejecting apparatus that ejects a bioorganic solution is used as a chip manufacturing apparatus that manufactures a bioscience element (biochip). Then, an object (landing target) that is a target of liquid ejection differs depending on the application of the liquid ejecting apparatus. Specifically, the landing target of the printing apparatus 100 described above is the recording paper 200. However, when the liquid ejecting apparatus is used for manufacturing a display device, for example, a substrate constituting the display device corresponds to the landing target.

DESCRIPTION OF SYMBOLS 100 ... Printing apparatus, 12 ... Carriage, 14 ... Movement mechanism, 16 ... Paper conveyance mechanism, 22 ... Ink cartridge, 24 ... Recording head, 26 ... Ejection surface, 28 (28K, 28Y, 28M, 28C) ... nozzle group, L1 ... first nozzle row, L2 ... second nozzle row, N (N1, N2) ... nozzle, 32 ... drive circuit, 50 ... pressure chamber, 52 ... supply path , 54... Storage chamber, 102... Control device, 104... Print processing unit, 60... Control unit, 62... Storage unit, 64. ... Internal I / F, 200 ... recording paper, 300 ... external device.

Claims (6)

A first nozzle row including a plurality of nozzles arranged in a first direction and a plurality of nozzles arranged in the first direction so that each position in the first direction is different from each nozzle in the first nozzle row A second nozzle array including nozzles is formed at a predetermined distance in a second direction intersecting the first direction, and the liquid ejected from each nozzle is landed on the landing target in the second direction. A liquid ejecting section that moves relatively;
The first dot formed on the landing target with the liquid ejected from the first nozzle of the first nozzle row, and the second formed on the landing target with the liquid ejected from the second nozzle of the second nozzle. The liquid ejecting apparatus, wherein the first nozzle and the second nozzle are formed in different dimensions so that a distance between the center of the dot and the center in the second direction is less than the predetermined distance. The first nozzle row is positioned in front of the second nozzle row in the traveling direction of the liquid ejecting unit with respect to the landing target, and the velocity of the liquid ejected from the first nozzle is ejected from the second nozzle. The liquid ejecting apparatus according to claim 1, wherein the dimensions of each of the first nozzle and the second nozzle are selected so as to exceed the speed of the liquid to be discharged. The liquid ejecting apparatus according to claim 2, wherein an in-tube cross-sectional area of the first nozzle is less than an in-tube cross-sectional area of the second nozzle. The first dot formed by the liquid ejected from the first nozzle and the second dot formed by the liquid ejected from the second nozzle closest to the first nozzle overlap or contact each other. 4. The liquid ejecting apparatus according to claim 1, wherein dimensions of each of the first nozzle and the second nozzle are selected. The dimension of each of the said 1st nozzle and the said 2nd nozzle is selected so that the position in the center 2nd direction may correspond with the said 1st dot and the said 2nd dot. Any liquid ejecting apparatus. The liquid ejecting apparatus according to claim 1, wherein an inertance of the first nozzle is equal to an inertance of the second nozzle.

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