JP2005313622A - Droplet spray head and droplet spray device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a droplet spray head which is of a matrix type and improved in bubble discharging performance out of a liquid channel, and to provide a droplet spray device which is improved and stabilized in ink feeding and droplet ejection. <P>SOLUTION: According to the structure of the droplet spray head, common channels 60 are arranged so as to form two upper and lower rows across an ink chamber unit 53, and branch channels 62 communicating with pressure chambers 52 are arranged so as to connect between the common channels 60 so as to communicate with a pressure chamber 52, followed by forming valves B1, B2 at one end of the common channel 60A and at the other end of the common channel 60B, respectively. Ink is fed from all ends of the common channels 60, and therefore the ink can be stably fed. Each branch channel 62 has no terminal end that can hinder smooth flow of the ink, and therefore ink stagnation does not occur, leading to efficient removing operation of bubbles through recovery processing. Further the valves B1, B2 are controlled based on application modes, and therefore ink feeding is stabilized at the time of ink charging, recovery action, and ink ejecting operation during image formation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid droplet ejecting head and a liquid droplet ejecting apparatus, and more particularly, to a liquid droplet ejecting head and a liquid droplet ejecting apparatus that eject and apply droplets to an object via a nozzle.

  As a liquid droplet ejecting head and a liquid droplet ejecting apparatus using the same, for example, an ink jet printer incorporating a recording head in which a large number of nozzles for ejecting ink are formed is known.

  The ink jet printer mechanically deforms the pressure chamber of the recording head, or energizes a heater arranged in the ink flow path to generate bubbles, and ejects ink from the nozzle of the pressure chamber by the pressure obtained thereby, Ink is applied to an object (recording medium) such as recording paper. The recording head and the recording medium are relatively moved, whereby a desired image or the like is formed on the recording medium. Therefore, the quality of the formed image greatly depends on the performance of the mounted recording head.

  By the way, inside the recording head, when ink is filled for the first time, bubbles may remain, or bubbles may enter the ink flow path from the nozzles due to pulsation generated in the ink. Since these bubbles hinder ink supply or absorb the pressure for ejecting ink, the amount of ink ejected from the nozzles (dot size to be ejected onto the recording medium), flight direction (droplet ejection position), flight Ink ejection defects such as inappropriate speed (droplet ejection position) may occur, and the quality of the recorded image may be reduced.

  As is well known in order to solve this problem, there is known a technique for discharging bubbles by performing recovery processing (flushing, wiping, preliminary ejection, nozzle suction, etc.) of the recording head as necessary. Also disclosed are inventions that aim to improve the discharge of bubbles and the stability of ink ejection from nozzles during image formation (see Patent Documents 1 to 4).

  For example, in Patent Document 1, the cross-sectional area of the ink supply unit to the pressure chamber is made smaller than the cross-sectional area of the common liquid chamber (provided on the upstream side of the pressure chamber) to increase the flow rate of ink in the ink supply unit. There is a description to improve the discharge.

  Patent Document 2 discloses an ink supply shape of a matrix type recording head with high-speed stability and further limits the flow path resistance of the ink supply unit numerically to improve high-speed and continuous ink ejection stability. There is a description.

  In Patent Document 3, there is a description that an ink supply port (liquid supply means referred to in Patent Document 3) is provided at the center or both ends of the mainstream of a matrix type recording head to reduce the flow path resistance to reduce the size of the recording head.

  In Patent Document 4, there is a description of improving the stability of ink ejection at a high speed and continuously by circulating and supplying ink through a buffer tank to reduce pulsation of the pump.

Patent Document 5 discloses a line-type head having ink supply ports at both longitudinal ends of the recording head.
JP 9-226142 A JP 2002-283585 A JP 2002-361867 A JP-A-8-132640 Japanese Patent Laid-Open No. 9-286098

  Patent Documents 1 and 2 disclose a technique for improving the bubble discharge property at the time of nozzle suction by increasing the flow velocity of the ink supply path or by providing a dummy nozzle, but there is a terminal portion in the ink supply path. There is a drawback that bubbles tend to accumulate at the end portion and the bubble discharge performance is insufficient. In the nozzle suction performed to discharge the bubbles accumulated in such a portion, it is necessary to suck a large amount of ink. In particular, when such a technique is applied to a long recording head, it is necessary to suck a larger amount of ink.

  In the technique disclosed in Patent Document 3, an invention has been made to lower the flow path resistance by providing ink supply ports at the main stream center or at both ends, but only one or two ink supply ports are provided. For example, line-type ink jets have a problem in that insufficient ink supply tends to occur with an increase in the size of the recording head. In addition, since the end portion is present in the ink supply path as in the above-described conventional technology, the bubble discharge performance is insufficient.

  In the technique disclosed in Patent Document 4, although various ink supply modes such as sub-tank replenishment, discharge replenishment, discharge recovery, and pressure discharge recovery in a line type recording head are disclosed, the internal flow path structure of the head is disclosed. No mention is made and application to a matrix type recording head is not shown.

  In the technique disclosed in Patent Document 5, although a recording head having ink supply ports at both longitudinal ends of the recording head is described, no specific ink supply is mentioned. Furthermore, such a recording head has a drawback that it is difficult to stably supply ink in a so-called long and large matrix type recording head.

  The present invention has been made in view of such circumstances, and in particular, a liquid droplet ejecting head with improved bubble discharge performance in a liquid flow path in a matrix type, and improvement in the stability of ink supply and liquid droplet ejection. An object of the present invention is to provide a liquid droplet ejecting apparatus that achieves the above.

  In order to achieve the above object, the present invention includes a liquid pressurizing unit that two-dimensionally arranges a plurality of liquid chambers in which nozzles for discharging droplets are formed and discharges a predetermined amount of liquid from the nozzles. In the liquid droplet ejecting head, at least two main channels having a channel port functioning as at least one of the liquid supply port and the liquid discharge port, and the main channel are communicated with the liquid chamber. A plurality of branch channels that are in communication with each other and can supply a liquid to each of the liquid chambers, and the two main channels have the channel ports formed at both ends of each of the main channels, and the plurality of branch channels Is characterized by being spanned between the two main flow paths.

  According to the present invention, for example, when the channel port is made to function as the liquid supply port, since the channel port is formed at both ends of the main channel, the liquid can be supplied from all the ends of the main channel, Liquid can be supplied stably during continuous liquid discharge operation. Accordingly, when the present invention is applied to a large droplet ejecting head such as a long recording head, the liquid can be stably supplied without being insufficient. Further, when the channel port is made to function as the liquid discharge port, the channel port is formed at both ends of the main channel, so that the liquid can be smoothly discharged from all the ends of the main channel.

Note that the number of such main flow paths is not limited to two, and two or more main flow paths may be provided. In this case, a channel opening may be formed at both ends of each main channel, or a channel port may be formed at both ends of at least two of the plurality of main channels.

  Here, the liquid is supplied from the liquid supply means to the main channel via the channel ports at both ends of the main channel. In the present specification, the “liquid supply means” broadly means means for supplying liquid to the droplet ejecting head. Specifically, for example, in addition to the liquid pipe in a mode in which liquid is forcibly supplied from a liquid tank or the like to the liquid pipe by a pump, the pump in an aspect directly connected to the pump without using such a liquid pipe Etc., all means capable of supplying liquid are meant broadly.

  According to the second aspect of the present invention, since the terminal portion as the flow channel is not formed in the main flow channel and the branch flow channel, liquid retention does not occur, and bubbles can be efficiently removed. . That is, two main flow paths are provided, and a plurality of branch flow paths are spanned over the main flow paths, so that it is possible to eliminate a terminal portion that hinders the smooth flow of liquid in the branch flow paths. Therefore, liquid retention does not occur, and bubbles can be efficiently removed by the recovery process.

  The “terminal portion” means a so-called corner portion of the flow path and a portion where the liquid is not circulated and is stagnation easily. Specifically, for example, a dead end portion of the flow path is exemplified.

  According to a third aspect of the present invention, there is provided a liquid pressurizing means that two-dimensionally arranges a plurality of liquid chambers in which nozzles for discharging droplets are formed and discharges a predetermined amount of liquid from the nozzles. A liquid droplet ejection head having two main flow paths each having a flow path port functioning as at least one of a liquid supply port and a liquid discharge port; the liquid chamber being in communication with the main flow channel; A liquid droplet ejecting head having a plurality of branch flow paths that are capable of supplying liquid to each liquid chamber, and each of the flow passage openings is formed at both ends of the two main flow paths, A first valve means provided at one end of the first main flow path for opening and closing a liquid flow through the flow path port; and a second main flow different from the first main flow path. A channel provided at an end of the first main channel on the side opposite to the position where the first valve means is disposed. Is characterized by comprising a second valve means for opening and closing the flow of liquid through the a valve control means for controlling said first valve means and said second valve means in accordance with the operation mode, the.

  According to the third aspect of the present invention, for example, when the flow path port functions as the liquid supply port, the flow path ports are formed at both ends of the two main flow paths. The liquid can be supplied from the end, and the liquid can be stably supplied during the liquid discharge operation at high speed and continuously. Thus, for example, when the present invention is applied to a droplet ejecting apparatus including a large droplet ejecting head such as a long recording head, the liquid can be stably supplied without being insufficient. In the case where the channel port functions as the liquid discharge port, the channel port is formed at both ends of the main channel, so that the liquid can be smoothly discharged from all the ends of the main channel.

  Further, two main flow paths are provided. Among these main flow paths, the first valve means provided at one end of the first main flow path and the second main flow path different from the first main flow path. The second valve means provided at the end opposite to the position where the first valve means is disposed, so that the flow of the liquid in the flow path can be reduced with a small number of valve means. It can be controlled efficiently. Further, since these valve means are controlled in accordance with the operation mode, it is possible to stabilize the liquid supply in the liquid filling and recovery operation, the liquid discharge operation, and the like.

  Note that if a plurality of branch passages are extended over and communicated with the two main passages, a terminal portion that hinders the smooth flow of the liquid in the branch portion can be eliminated. Therefore, liquid retention does not occur, and bubbles can be efficiently removed by the recovery process.

  According to the present invention described in claim 4, since the operation mode has at least two modes among the start-up mode, the droplet ejection mode, the standby mode, and the recovery mode, The flow of ink can be controlled, and stable ink ejection operation is always possible.

  According to the present invention described in claim 5, in the start-up mode, the valve control means closes the first valve means and opens the second valve means, or opens the first valve means and the second valve means. Since the step of closing the valve means is included, the filling / replacement of the liquid in the first main channel and the second main channel can be performed efficiently.

  According to the sixth aspect of the present invention, in the start-up mode, the valve control means includes the step of closing both the first valve means and the second valve means. It is possible to efficiently fill / replace the two main flow paths and the branch flow paths.

  According to the seventh aspect of the present invention, in the start-up mode, the valve control means includes a step of opening both the first valve means and the second valve means to perform preliminary discharge. The refill property at the time, that is, the responsiveness of liquid replenishment is improved, and preliminary ejection can be performed efficiently.

  According to the present invention as set forth in claim 8, in the droplet ejection mode, the valve control means includes the step of opening both the first valve means and the second valve means. Improves.

  According to the present invention as set forth in claim 9, in the recovery mode, the valve control means includes a step of opening both the first valve means and the second valve means to perform preliminary discharge. The refill property, that is, the responsiveness of liquid replenishment is improved, and the preliminary discharge can be performed efficiently.

  According to the tenth aspect of the present invention, at the time of preliminary discharge, the liquid is pressurized and supplied by the liquid supply means connected to the channel port, so that the capability of preliminary discharge can be enhanced.

  According to the present invention described in claim 11, since the valve means is a valve that regulates the flow of the liquid, the flow of the liquid in the first main flow path, the second main flow path, and the branch flow path is finely controlled. it can.

  According to the present invention described in claim 12, since the main channel and the branch channel are arranged so as to have a substantially rotational symmetry with respect to the arrangement center of the plurality of liquid chambers, Thus, the effective channel lengths of the main channel and the branch channel can be made substantially constant, and a channel excellent in liquid filling / substitution and refillability can be configured.

  In this specification, the “recording medium” is a medium (called an image forming medium, a recording medium, an image receiving medium, a recording paper, or the like) on which droplets are sprayed, and is a continuous sheet, a cut sheet, a seal sheet, Regardless of resin sheets such as OHP sheets, films, cloths, and other materials and shapes, various media are included.

  According to the present invention, since the liquid is supplied from all ends of the main flow path, the liquid can be stably supplied for high-speed and continuous liquid discharge operation. In addition, since the terminal portion is not formed in the main channel or the branch channel and the liquid is not retained, the bubbles can be efficiently removed by the recovery process. Furthermore, it is possible to efficiently control the flow of the liquid in the flow path according to the filling / replacement, refilling, and preliminary discharge of the liquid with a small number of valve means.

  FIG. 1 is a configuration diagram schematically showing the configuration of an ink jet printer to which a droplet ejecting head and a droplet ejecting apparatus according to an embodiment of the present invention are applied.

  As shown in the figure, this inkjet printer 10 includes an image forming unit 12 having a plurality of recording heads 12K, 12C, 12M, and 12Y provided for each ink color, and each recording head 12K, 12C, 12M, and 12Y. An ink storage / loading unit 14 for storing ink to be supplied, a paper supply unit 18 for supplying recording paper 16 (recording medium), a decurling unit 20 for removing curl of the recording paper 16, and the image formation The recording paper 16 is disposed while facing the nozzle surfaces (not shown in FIG. 1; lower surface of reference numeral 78 in FIG. 6) of the recording heads 12K, 12C, 12M, and 12Y of the section 12 while maintaining the flatness of the recording paper 16. A suction belt conveyance unit 22 for conveying the image, an image detection unit 24 for reading an image formation result by the image forming unit 12, and a paper discharge unit 26 for discharging the image-formed recording paper 16 to the outside. It is equipped with a.

  In the paper supply unit 18, roll paper (continuous paper) is shown as an example of the recording paper 16, but a plurality of roll papers having different paper widths or paper qualities may be provided side by side. Further, instead of the roll paper or in combination with this, the paper may be supplied from a cassette in which cut papers are stacked and loaded. In addition, when the configuration is such that a plurality of types of recording paper can be used, an information recording body such as a barcode or a wireless tag that records paper type information is attached to a roll paper magazine or the like, and information on the information recording body is stored in a predetermined manner. It is preferable that the type of paper to be used is automatically determined by reading by the reading device, and ink ejection control is performed so as to realize appropriate ink ejection according to the type of paper.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been wound as roll paper. In order to remove the curl, the recording paper 16 is heated while being bent in the direction opposite to the curl direction of the recording paper by the heating drum 30 in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the image forming surface is slightly curled outward.

  In the case of an apparatus configuration using roll paper, a cutter 28 is provided at the subsequent stage of the decurling unit 20 as shown in the figure, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes, for example, a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording paper 16, and a movable blade (or a round blade) 28B that moves along the fixed blade 28A. A fixed blade 28A is provided on the back side, and a movable blade 28B is disposed on the image forming surface side across the conveyance path. Note that the cutter 28 is not necessary when cut paper is used.

  After the decurling process, the cut recording paper 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and at least a portion facing the nozzle surface of the image forming unit 12 and the sensor surface of the image detection unit 24 is a horizontal plane. (Flat surface).

  The belt 33 has a width that is greater than the width of the recording paper 16, and a number of unillustrated suction holes are formed on the belt surface. An adsorption chamber 34 is provided at a position facing the nozzle surface of the image forming unit 12 and the sensor surface of the image detection unit 24 inside the belt 33 spanned between the rollers 31 and 32. Is sucked by the fan 35 to make the suction chamber 34 have a negative pressure, whereby the recording paper 16 on the belt 33 is sucked and held.

  When the power of a motor (denoted by reference numeral 152 in FIG. 9) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, the belt 33 is driven in the clockwise direction in FIG. The recording paper 16 held thereon is conveyed from left to right in FIG.

  In addition, since ink adheres to the belt 33 in borderless printing or the like, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the image forming area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, an air blowing method of spraying clean air, or a combination thereof.

  In addition to this, a mode in which a roller / nip conveyance mechanism is used in place of the suction belt conveyance unit 22 is also conceivable. There is a problem that the image is likely to bleed due to contact. Therefore, it can be said that a suction belt conveyance mechanism that does not contact the image surface in the image forming region as in this example is a preferable mode.

  A recording paper detection unit 40 is provided on the upstream side of the image forming unit 12 on the recording paper conveyance path formed by the suction belt conveyance unit 22. The recording paper detection unit 40 detects the position of the recording paper 16 before image formation in order to determine ink ejection timing at the time of image formation, and detects the detection signal to a system controller (described as reference numeral 132 in FIG. 9) described later. Send.

  As shown in FIG. 2, the image forming unit 12 is a so-called full line type head in which line type heads having a length corresponding to the maximum paper width are arranged in a direction (main scanning direction) perpendicular to the recording paper conveyance direction. Although a detailed structural example will be described later, each of the recording heads 12K, 12C, 12M, and 12Y has an ink discharge port (nozzle) over a length exceeding at least one side of the maximum size recording paper 16 targeted by the inkjet printer 10. It is composed of a plurality of line type heads.

  A recording head 12K corresponding to each color ink in the order of black (K), cyan (C), magenta (M) and yellow (Y) from the upstream side along the feeding direction of the recording paper 16 (hereinafter referred to as the recording paper transport direction). , 12C, 12M, 12Y are arranged. A color image can be formed on the recording paper 16 by discharging the color inks from the recording heads 12K, 12C, 12M, and 12Y while the recording paper 16 is conveyed.

  As described above, according to the image forming unit 12 in which the full line type head covering the entire width of the paper is provided for each ink color, the recording paper 16 and the image forming unit 12 are relatively moved in the sub-scanning direction. An image can be recorded on the entire surface of the recording paper 16 with only one operation (ie, with one sub-scan). Thereby, it is possible to form an image at a higher speed than the shuttle type head in which the recording head reciprocates in the main scanning direction, and the productivity can be improved.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink and dark ink are added as necessary. May be. For example, it is possible to add a recording head that discharges light ink such as light cyan and light magenta. Also, the arrangement order of the color heads is not particularly limited.

  In FIG. 1, an ink storage / loading unit 14 has tanks for storing inks of colors corresponding to the recording heads 12K, 12C, 12M, and 12Y. Each tank is a main flow path (reference numeral 69 in FIG. 8) described later. And the recording heads 12K, 12C, 12M, and 12Y. The ink storage / loading unit 14 includes notifying means (for example, display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. doing.

  The image detection unit 24 includes an image sensor (not shown) for capturing the droplet ejection result of the image forming surface of the recording paper 16 by the image forming unit 12, and nozzle clogging is performed from the droplet ejection image read by the image sensor. It functions as a means for checking other ejection defects.

  Note that the image detection unit 24 of the present embodiment is composed of a line sensor having a light receiving element array that is wider than at least the ink ejection width (image formation width) by the recording heads 12K, 12C, 12M, and 12Y. This line sensor includes, for example, an R sensor array in which photoelectric conversion elements (pixels) provided with a red (R) color filter are arranged in a line, and a G sensor array provided with a green (G) color filter. And a color separation line CCD sensor comprising a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  The image detection unit 24 reads a pattern in which an image is formed by the recording heads 12K, 12C, 12M, and 12Y for each color, and detects ejection of each recording head. The ejection determination is performed based on the detection result by the ejection detection, and this ejection determination includes the presence / absence of ejection, measurement of the dot size, measurement of the dot landing position, and the like.

  A drying unit 42 is provided following the image detection unit 24. The drying unit 42 is means for drying the image surface on which the image is formed, and for example, a heating fan is used. Since it is preferable to avoid contact with the image forming surface until the ink after image formation is dried, a method of blowing hot air is preferable. When an image is formed on a porous paper with a dye-based ink, the paper is prevented from coming into contact with anything that causes destruction of dye molecules such as ozone by blocking the pores of the paper by pressurization. Has the effect of improving sex.

  A heating / pressurizing unit 44 is provided following the drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined surface uneven shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The recording paper 16 on which the image is thus formed is discharged from the paper discharge unit 26.

  Next, the structure of the recording head will be described. Since the recording heads 12K, 12C, 12M, and 12Y provided for each ink color have the same structure, hereinafter, the recording head is represented by reference numeral 50.

  FIG. 3A is a plan perspective view showing a structural example of the recording head 50, and FIG. 3B is a plan perspective view showing another structural example of the recording head 50. In order to increase the dot pitch for image formation on the recording paper 16 surface, it is necessary to increase the nozzle pitch in the recording head 50. As shown in FIG. 3A, the recording head 50 of this example includes a plurality of ink chamber units 53 each including a nozzle 51 from which ink droplets are ejected and a pressure chamber 52 corresponding to each nozzle 51. It has a structure that is arranged in a matrix, thereby achieving an apparent increase in nozzle pitch density.

  That is, in the recording head 50 according to the present embodiment, as shown in FIG. 3A, a plurality of nozzles 51 for ejecting ink correspond to the entire width of the recording paper 16 in a direction substantially perpendicular to the recording paper transport direction. This is a full line type head having one or more nozzle rows arranged over the entire length. Further, as shown in FIG. 3B, a recording head 50 ′ having a length corresponding to the entire width of the recording medium can be obtained by arranging the recording heads 50 arranged in a short two-dimensional pattern in a staggered manner. Good.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and the nozzle 51 and the supply port 54 are provided at both corners on the diagonal line. Each pressure chamber 52 communicates with a branch channel (described as reference numeral 62 in FIG. 5), which will be described later, via a supply port 54. The shape of the pressure chamber 52 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon and other polygons, a circle, and an ellipse.

  As shown in FIG. 4, the recording head 50 has a large number of ink chamber units 53 having such a structure in a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. It has a structure in which they are arranged along with each other and arranged in a lattice pattern with a fixed arrangement pattern. With a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along a certain angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × COSθ. .

  That is, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which the number of nozzle rows projected so as to be aligned in the main scanning direction is 2400 per inch (2400 nozzles / inch). Hereinafter, for convenience of explanation, it is assumed that the nozzles 51 are linearly arranged at a constant interval (pitch P) along the longitudinal direction (main scanning direction) of the head.

  When driving a nozzle with a full-line head having a nozzle row corresponding to the full width of the paper, (1) all the nozzles are driven simultaneously, (2) the nozzles are driven sequentially from one side to the other ( 3) Drive control such as dividing the nozzle into blocks and sequentially driving from one side to the other for each block is performed, and one line in the width direction of the recording paper 16 (direction orthogonal to the recording paper transport direction) ( The driving of the nozzle that forms an image of a line of dots in one row or a line made up of a plurality of dots is defined as main scanning.

  In particular, when the nozzles 51 arranged in the matrix as shown in FIG. 4 are driven, the main scanning as described in the above (3) is preferable. That is, nozzles 51-11, 51-12, 51-13, 51-14, 51-15, and 51-16 are made into one block (other nozzles 51-21,..., 51-26 are made into one block, The nozzles 51-31,..., 51-36 are set as one block...) And the nozzles 51-11, 51-12,. An image of one line is formed in the width direction.

  On the other hand, by relatively moving the above-described full-line type head and the paper, it is possible to repeatedly perform image formation of one line formed by the above-described main scanning (a line composed of a single line of dots or a line composed of a plurality of lines of dots). Is defined as sub-scanning. In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example.

  As shown in FIG. 5, the recording head 50 includes an ink supply system including a common channel 60 (60A, 60B) as a main channel, a branch channel 62, a main supply port 64, valves B1, B2, and the like.

  The common flow paths 60 are provided in two upper and lower rows so as to sandwich the ink chamber units 53 arranged in a matrix in a staggered manner, and are arranged, for example, along the main scanning direction. In addition, the lower common flow path 60 is represented by reference numeral 60A, and the upper common flow path 60 is represented by reference numeral 60B. A main supply port 64 is formed at the left and right end portions 66 of the common flow paths 60A and 60B, and an ink supply supply pipe 68 is connected to the main supply port 64.

  The supply pipe 68 is provided with valves B1 and B2 as valve means. The respective valves B1 and B2 are arranged diagonally with respect to the recording head 50. In the present embodiment, as an example, the valves B1 and B2 are attached to the lower right and upper left supply pipes 68 in FIG. It has been. The supply pipes 68 merge to form a main flow path 69.

  On the other hand, the branch channels 62 are provided in a plurality of rows along the main scanning direction in the same row as the arrangement of the pressure chambers 52 having the angle θ, and are connected to the upper and lower common channels 60. Therefore, the branch flow paths 62 are arranged so as to span the two upper and lower common flow paths 60. Each branch channel 62 is connected to the supply port 54 of each pressure chamber 52.

  Here, as shown in the figure, the common channel 60 and the branch channel 62 are preferably formed so as to have a substantially rotational symmetry with respect to the arrangement center of the ink chamber units 53 arranged in a staggered matrix. . That is, the effective flow lengths of the common flow channel 60 and the branch flow channel 62 on the left side from the arrangement center of the ink chamber units 53 group, which is the center position of the recording head 50, and the common flow channel 60 and the branch flow channel 62 on the right side from this center. The effective length of the flow path is set to be substantially constant. Accordingly, since the flow paths having substantially the same shape can be formed on the left side and the right side of the recording head 50, it is possible to form a flow path having excellent liquid filling / replacement and refill properties.

  When ink is supplied from the supply pipe 68 by the ink supply system having such a configuration, the ink is supplied to each pressure chamber 52 through the common flow path 60 and the branch flow path 62.

  Next, the internal structure of the recording head 50 will be described.

  FIG. 6 is a longitudinal sectional view of the recording head 50. FIG. 6 shows a section taken along the line AA in FIG. 5 for convenience of explaining the common channel 60, the branch channel 62, and the main supply port 64. .

  As shown in FIG. 6, the recording head 50 is configured by a laminated structure of a diaphragm 70 and a plurality of substrates 71, 72, 74, 76. Reference numeral 80 denotes a piezoelectric element (piezo element) as an actuator.

  The diaphragm 70 of the present embodiment is made of a conductive member, is electrically connected to the lower surface electrode of the piezoelectric element 80, and functions as a common electrode.

  An opening for the pressure chamber 52 is formed in the substrate 72, and a supply port 54 that supplies ink to the pressure chamber 52 from a branch channel 62 formed in the substrate 76 is formed in the substrate 74.

  Further, a common flow path 60 is formed in the substrate 71 (FIG. 6 is only partially shown because of the AA cross section of FIG. 5). Although not shown in FIG. 6, in order to connect the common channel 60 formed in the substrate 71 and the branch channel 62 formed in the substrate 76, the substrate 70 is located at a position corresponding to the position of the branch channel 62. , 72 and 74 are formed. The main supply port 64 is connected to a supply pipe 68 that is a liquid supply means.

  The inner diameter of the supply pipe 68 and the inner diameter of the main supply port 64 are formed with the same dimensions, and when the supply pipe 68 and the main supply port 64 are connected, the respective openings are connected without shifting. Therefore, the main supply port 64 and the supply pipe 68 can be formed in a straight pipe shape, and can flow into the common flow path 60 without stopping ink. Reference numeral 90 denotes a rubber packing for preventing ink leakage that seals the main supply port 64 and the supply pipe 68.

  A nozzle plate 78 on which the nozzles 51 are formed is bonded to the lower surface of the substrate 76, and ink discharge openings 86 that connect the nozzles 51 and the pressure chambers 52 are formed in the substrates 74 and 76.

A flexible wiring board (not shown) that transmits a drive signal for driving and controlling the piezoelectric element 80 is provided on the upper surface of the piezoelectric element 80.

  Now, as shown in FIG. 5, the common channel 60 is connected to the supply pipe 68 at its end, and ink is supplied from all the ends of the common channel 60.

  In addition, the ink supply system including the common flow channel 60, the branch flow channel 62, the main supply port 64, and the like does not include a terminal portion, that is, a portion that becomes a dead end of the flow channel. Specifically, the dead end portion of the branch flow path 62 is eliminated by the branch flow path 62 arranged so as to be stretched over the two upper and lower rows of common flow paths 60. As a result, the ink does not stop, and the ink flows smoothly and smoothly.

  Further, in FIG. 6, since the main supply port 64 and the supply pipe 68 have a straight pipe shape, ink can be supplied without changing the direction of ink flow. In addition, since there are no protrusions or the like that cause retention in the ink flow path, the direction of ink flow does not change, and ink retention can be prevented. Note that if the width of the common flow path 60 and the branch flow path 62 in the lateral direction (that is, the direction parallel to the nozzle surface of the nozzle plate 78) is increased, the flow rate of ink per unit time can be increased. 50 increases in size in the lateral direction, and the density of the nozzle 51 decreases. Therefore, in order to prevent this, it is desirable that the common flow channel 60 and the branch flow channel 62 are widened in the vertical direction (that is, the direction perpendicular to the nozzle surface of the nozzle plate 78).

  In order to attach such a recording head 50 to the ink jet printer 10, the head block 97 shown in FIG. That is, after the recording head 50 is fitted into the holder 92, the attachment 94 is sandwiched and fixed by the connecting plate 96. The connection plate 96 is provided with the supply pipe 68, and the main supply port 64 and the supply pipe 68 of the recording head 50 are connected by the fixing. Although not shown, the attachment 94 and the connecting plate 96 are also attached to the front side of the figure.

  FIG. 8 is a schematic diagram showing the configuration of the ink supply system on the main body side of the inkjet printer 10. The ink jet printer 10 includes a sub tank 102, pumps P1 and P2, buffer tanks 104 and 106, and the like between the ink supply tank 100 and the recording head 50. Reference numeral 110 denotes a maintenance unit for the recording head 50.

  The ink supply tank 100 is a base tank for supplying ink, and is installed in the ink storage / loading unit 14 described with reference to FIG. There are two types of ink supply tank 100: a system that replenishes ink from a replenishment port (not shown) when the remaining ink level is low, and a cartridge system that replaces the tank as a whole. When changing, the latter cartridge system is suitable. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type.

  The sub tank 102 collects ink supplied from the ink supply tank 100 and removes bubbles in the ink as much as possible. Instead of or in combination with the sub tank 102, a filter (not shown) for removing foreign substances and bubbles may be provided. The sub tank 102 is provided with a sensor (not shown) connected in a circuit with a system controller 132 (see FIG. 9), and the system controller 132 detects the presence or absence of ink. When the system controller 132 no longer detects the remaining ink, it is determined that the ink has run out in the ink supply tank 100.

  The buffer tanks 104 and 106 are provided in the vicinity of the recording head 50 or integrally with the recording head 50 between the sub tank 102 and the recording head 50. These buffer tanks absorb the pulsation (internal pressure fluctuation) generated in the pressure in the common flow path 60 and the branch flow path 62 by driving the pumps P1 and P2, and maintain the pressure in the recording head 50 at an appropriate constant value. This is to obtain a damper effect.

  Also, in the vicinity of the recording head 50, a maintenance unit comprising a cap 116 as a means for preventing the nozzle 51 from drying or preventing an increase in ink viscosity near the nozzle 51, a cleaning blade 118 as a means for cleaning the nozzle surface, and the like. 110 is provided.

  The maintenance unit 110 can be moved relative to the recording head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the recording head 50 as necessary.

  The cap 116 is displaced up and down relatively with respect to the recording head 50 by an elevator mechanism (not shown). The cap 116 is raised to a predetermined raised position when the power is turned off or during image formation standby, and is brought into close contact with the nozzle plate 78 of the recording head 50, thereby covering the nozzle plate surface of the recording head 50 with the cap 116.

  Here, the recovery process will be described. When the frequency of use of a specific nozzle 51 becomes low during image formation or standby, and ink is not ejected for a certain period of time, the ink solvent in the vicinity of the nozzle evaporates and the ink is discharged. The viscosity becomes high. In such a state, even if the piezoelectric element 80 of the recording head 50 is operated, ink cannot be ejected from the nozzles 51.

  Prior to this, the piezoelectric element 80 is operated (within the range of viscosity that can be discharged by the operation of the piezoelectric element 80), and the deteriorated ink (ink near the nozzle whose viscosity has increased) is discharged to the cap 116. Then, recovery processing by preliminary discharge (purge, idle discharge, spit discharge, dummy discharge) is performed.

  In addition, when bubbles are mixed in the ink in the recording head 50 (in the pressure chamber 52), the ink cannot be ejected from the nozzle 51 even if the piezoelectric element 80 is operated. In such a case, the cap 116 is brought into close contact with the lower surface of the nozzle plate 78 of the recording head 50, and a recovery process is performed in which the pump P3 is driven to suck and remove ink mixed with bubbles in the pressure chamber 52. The collected ink is sent to the collection tank 120 and returned to the sub tank 102 as necessary.

  This suction operation is also performed when the ink is initially loaded into the head or when the ink is used after being stopped for a long time, and defective ink having increased viscosity (solidified) is sucked out.

  Since the suction operation is performed on the entire ink in the pressure chamber 52, the amount of ink consumption increases. Therefore, when the increase in the viscosity of the ink is small, it is preferable to perform the preliminary ejection described above.

  The cleaning blade 118 is made of an elastic member such as rubber, and is slidably provided on the lower surface of the nozzle plate 78 of the recording head 50 by a blade moving mechanism (wiper) (not shown). When ink droplets or foreign substances adhere to the lower surface of the nozzle plate 78, the cleaning blade 118 is slid on the lower surface of the nozzle plate 78 to wipe the surface of the lower surface of the nozzle plate 78 and clean the lower surface of the nozzle plate 78. During cleaning by this blade mechanism, preliminary discharge is performed after cleaning in order to prevent foreign matters from entering the nozzle 51 by the cleaning blade 118.

  FIG. 9 is a principal block diagram showing the system configuration of the inkjet printer 10. The inkjet printer 10 includes a communication interface 130, a system controller 132, a memory 134, a motor driver 136, a heater driver 138, a valve driving device 140, a pump driving device 141, a print control unit 142, an image buffer memory 144, a head driver 146, and the like. Yes.

  The communication interface 130 is an interface unit that receives image data sent from the host computer 150. As the communication interface 130, a serial interface such as USB, IEEE 1394, Ethernet, and wireless network, and a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 150 is taken into the inkjet printer 10 via the communication interface 130 and temporarily stored in the memory 134. The memory 134 is a storage unit that temporarily stores an image input via the communication interface 130, and data is read and written through the system controller 132. The memory 134 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 132 is a control unit that controls each unit such as the communication interface 130, the memory 134, the motor driver 136, and the heater driver 138. The system controller 132 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 150, read / write control of the memory 134, and the like, and controls the motor 152 and heater 154 of the transport system. A control signal to be controlled is generated.

  The motor driver 136 is a driver (drive circuit) that drives the motor 152, and the heater driver 138 is a driver that drives the heater 154 of the drying unit 42. The valve driving device 140 drives the valves B1 and B2, and the pump driving device 141 drives the pumps P1, P2, and P3. These drivers and driving devices are driven in accordance with instructions from the system controller 132, respectively.

  The print control unit 142 has a signal processing function for performing various processes such as processing and correction for generating a signal for image formation control from image data in the memory 134 under the control of the system controller 132, and the generated image A control unit that supplies a formation control signal (image formation data) to the head driver 146. Necessary signal processing is performed in the print control unit 142, and the ink droplet ejection amount and ejection timing control (droplet ejection control) of the recording head 50 are performed via the head driver 146 based on this image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 142 includes an image buffer memory 144, and image data, parameters, and other data are temporarily stored in the image buffer memory 144 when image data is processed in the print control unit 142. In the figure, the image buffer memory 144 is shown as being attached to the print control unit 142, but can also be used as the memory 134. Also possible is an aspect in which the print control unit 142 and the system controller 132 are integrated to form a single processor.

  The head driver 146 drives the recording heads 12K, 12C, 12M, and 12Y for each color based on the image formation data given from the print control unit 142. The head driver 146 may include a feedback control system for keeping the head driving condition constant.

  Various control programs are stored in a program storage unit (not shown), and the control programs are read and executed in accordance with commands from the system controller 132. The program storage unit may be a semiconductor memory such as a ROM or EEPROM, a magnetic disk, or a memory card or a PC card with an external interface. Of course, you may provide several recording media among these recording media. The program storage unit may also be used as a recording unit (not shown) for operating parameters.

  The image detection unit 24 is a block including the line sensor described with reference to FIG. 1, reads an image formed on the recording paper 16, performs necessary signal processing, etc. Variation), and the detection result is provided to the print control unit 142.

  The print control unit 142 performs various corrections on the recording head 50 based on information obtained from the image detection unit 24 as necessary.

  In the example shown in FIG. 1, the image detection unit 24 is provided on the image forming surface side, and the image forming surface is illuminated by a light source (not shown) such as a cold cathode tube disposed near the line sensor. The reflected light is read by an image sensor, but other configurations may be used when implementing the present invention.

  Next, the operation of the liquid droplet ejecting head according to the present invention will be described.

  First, an operation sequence when the ink jet printer 10 is turned on (start-up mode) will be described with reference to FIGS. 5 and 8 using FIG.

  When the power is turned on for the first time, such as when the ink jet printer 10 is started up, the valves B1 and B2 remain open (step S10). In this state, the pumps P1 and P2 are both driven as liquid supply, so The sub tank 102 and the buffer tanks 104 and 106 are filled with ink until the ink in the tanks 104 and 106 reaches a predetermined liquid level (step S12). Note that another pump (not shown) may be used for filling the sub tank 102.

  Next, in order to reliably fill the common flow path 60A with ink, the valve B1 is kept open, the valve B2 is closed, the pump P1 is driven to feed liquid, and the pump P2 is driven to suck liquid, thereby ink. Is circulated (step S14). After a predetermined time has elapsed, the valve B1 is closed and the valve B2 is opened to reliably fill the common flow path 60B with ink, and the pump is driven in the same manner as S14 to circulate ink (step S16). As a result, ink is filled in the common flow paths 60A and 60B, and the bubbles are smoothly discharged without preliminary ejection. The steps S14 and S16 may have a configuration in which the order is changed.

  Further, in step S18, the open valve of the valves B1 and B2 is closed, and both the valves B1 and B2 are closed, and the pump is driven to circulate ink as in S16. Thereby, the ink supplied to the common flow paths 60A and 60B is filled in the branch flow path 62, and the bubbles in the branch flow path 62 are smoothly discharged without preliminary discharge.

  Next, both the valves B1 and B2 are opened, and the pump is driven to perform preliminary discharge while circulating ink as in S18, and ink containing bubbles is discharged from the nozzle (step S20). Thereby, ink containing bubbles in the pressure chamber 52 can be discharged through the nozzle 51. In addition, since both the valves B1 and B2 are opened, the discharged ink is smoothly refilled.

  Furthermore, in order to reliably discharge ink containing bubbles from the common flow path 60 and the branch flow path 62, at least one of the pumps P1 and P2 is stopped, such as stopping the pump P2 while the pump P1 is driven to feed liquid. The ink is driven and supplied while being pressurized (step S22). As a result, the ink containing bubbles in the common channel 60, the branch channel 62 and the pressure chamber 52 can be reliably discharged from the nozzle 51. Since the valves B1 and B2 are opened, ink is smoothly supplied to the recording head 50.

  After these processes are performed, the image forming standby state (standby mode) is entered in step S24. Pumps P1 and P2 are stopped. In addition to Step S20 and Step S22 described above, in the recovery process described below, the ink discharged from the nozzle 51 is ejected by the cap 116 and collected, and returned to the sub tank 102 via the collection tank 120.

  Here, the operation of the recording head 50 when the inkjet printer 10 is started up will be described.

  In FIG. 5, ink is supplied from the supply pipe 68 to the recording head 50 through the main supply port 64, and the common flow paths 60A and 60B are filled with ink. Next, ink is filled into the branch channel 62 from the common channels 60A and 60B. Since ink circulation is performed by such ink filling, ink can be reliably filled / replaced. Furthermore, ink is filled in the pressure chamber 52 and the nozzle 51, preliminary ejection is performed from the nozzle 51, and ink containing bubbles can be reliably discharged from the nozzle 51 in the pressure chamber 52.

  Next, the operation sequence after the image formation standby mode in step S24 in FIG. 10 will be described with reference to FIG.

  If it is determined in step S30 that the image formation is on standby, the standby time is measured in step S32. If the predetermined standby time has elapsed and ink has not been ejected from the nozzles for a certain time or longer, and the system controller 132 (see FIG. 9) determines that the print head 50 needs to be recovered, the process proceeds to step S34. Then, the piezoelectric element 80 of the recording head 50 is driven while both the valves B1 and B2 are opened, and the ink is discharged from the nozzles. Defective ink such as bubbles and thickened ink in the pressure chamber 52 can be discharged through the nozzle 51.

  Next, in order to reliably discharge the defective ink, at least one of the pumps P1 and P2 is driven in step S36 to supply the ink while being pressurized. Thus, defective ink generated in the vicinity of the nozzle 51 due to thickening over time can be reliably discharged. In addition, when bubbles are generated in the ink, the ink containing the bubbles can be discharged. Since the valves B1 and B2 are opened, the ink is supplied smoothly. Then, it returns to step S30.

  Next, a droplet ejection mode during image formation will be described.

  In FIG. 9, at the time of image formation, image data to be printed is input from the host computer 150 to the inkjet printer 10 via the communication interface 130, and the image data is stored in the image memory 134. The system controller 132 drives the motor via the motor driver 136, pulls out the recording paper 16 from the roll paper shown in FIG. The system controller 132 causes the cutter 28 to cut the recording paper 16 to a paper size predetermined by the image data via the print control unit 142, and the cut recording paper 16 is sent to the suction belt conveyance unit 22. Next, the system controller 132 drives the motor 108 via the motor driver 136, and the rollers 31 and 32 are controlled to rotate. As a result, the recording paper 16 is conveyed to the image forming unit 12 by the belt 33. When the recording paper 16 reaches the image forming unit 12, an image is formed on the recording paper 16 by the recording head 50. In other words, the image data stored in the memory 134 in FIG. 9 is sent to the print control unit 142 and converted into dot data for each ink color via the head driver 146. The head driver 146 takes in the dot data and generates a drive control signal for the recording head 14.

  By applying a drive control signal generated by the head driver 146 to the recording head 50, ink is ejected from the nozzle 51 onto the image recording surface of the recording paper 16. Specifically, the system controller 132 controls the ink ejection timing from the recording head 50 in synchronization with the conveyance speed of the recording paper 16 based on the detection result from the recording paper detection unit 40, and conveys the recording paper 16. An image is formed on the recording paper 16 without stopping. The recorded recording paper 16 is conveyed by the suction belt conveyance unit 22 and discharged from the paper discharge unit 26.

  In FIG. 6, by applying a driving voltage to the piezoelectric element 80 bonded to the vibration plate 70, the piezoelectric element 80 is deformed to pressurize the pressure chamber 52, and ink is ejected downward from the nozzle 51. At this time, as shown in FIG. 8, the ink in the sub tank 102 passes through the main flow path 69 due to the pressure difference between the buffer tanks 104 and 106 and the pressure chamber 52 (water head difference caused by ink ejection from the nozzle 51). 50, and is supplied from the common channel 60 to the pressure chamber 52 through the branch channel 62.

  In FIG. 5, during image formation, the valves B <b> 1 and B <b> 2 are opened, and in this state, the piezoelectric element 80 of the recording head 50 is driven and ink is ejected by the nozzles 51. Pumps P1 and P2 are not driven. Since the supply pipes are connected at all ends of the common flow path, ink can be supplied from all ends of the common flow path, so that ink can be stably supplied even during high-speed and continuous ink discharge operations. Can supply. Further, the valves B1 and B2 may be closed and then opened again in order to perform the operations more reliably.

  Next, a recovery mode for removing bubbles generated in the ink will be described.

  FIG. 12 is an operation sequence showing a recovery mode when an image defect occurs.

  If an image defect is detected by the image detection unit 24 in step S40, the valve B2 is first closed to refill the common flow path 60A with ink (step S42). Next, the valve B1 is closed and the valve B2 is opened to fill the common flow path 60B with ink (step S44). Thereby, the air interposed in the common flow paths 60A and 60B can be taken into the ink as bubbles. In addition, step S42 and step S44 are good also as a structure which replaced the order.

  Further, in step S46, the open valve of the valves B1 and B2 is closed, and both the valves B1 and B2 are closed, so that the pump P1 is fed and the pump P2 is sucked. Drive to circulate ink. Thereby, the ink supplied to the common flow paths 60A and 60B is filled in the branch flow path 62, and the bubbles in the branch flow path 62 are smoothly discharged without preliminary discharge.

  Thereafter, both the valves B1 and B2 are opened, and the piezoelectric element 80 of the recording head 50 is driven to discharge the defective ink containing bubbles from the nozzle 51 (step S48).

  Further, in order to reliably discharge the defective ink, at least one of the pumps P1 and P2 is driven to supply the ink while pressurizing it (step S50). At this time, the pressure generated in the ink in the common flow path 60, the branch flow path 62, and the pressure chamber 52 becomes larger than the pressure at the time of ink ejection obtained by the piezoelectric element 80 during image formation, and the ink in the recording head 50 is discharged from the nozzle 51 to drain. With this discharge, the defective ink remaining in the pressure chamber 52 is reliably discharged from the nozzle 51. Thereafter, the process returns to step S40.

  In this way, defective ink can be efficiently removed, and bubbles can be prevented from remaining. Therefore, the number of recovery processes can be reduced, and a decrease in utilization due to interruption of image formation can be prevented.

  Although the general operation sequence of the apparatus has been described above, the modes may be selectively combined according to the operating rate, the print content, and the like. An example is shown in FIG.

  As shown in FIG. 13, it is desirable to use the start-up mode, the droplet ejection mode, the standby mode, and the recovery mode in the quiet processing, and the start-up mode and the droplet ejection mode in the continuous processing for full-screen printing.

  In addition, although the structure of valve | bulb B1, B2 mentioned above may provide the valve | bulb of the existing structure in two places, it is suitable to use what is shown, for example to Fig.14 (a) (b). The valve mechanism shown in the figure switches the opening and closing timing of the supply pipe 68 by two cams 162 and 164 having different shapes fixed to the output shaft of one motor 160.

  As shown in FIG. 14 (c), each of the cams 162 and 164 has a substantially disk shape. One cam 162 is cut off at the top and bottom, and the other cam 164 is cut at one side and the bottom. It is missing. In addition, a tube pipe made of an elastic material such as rubber is used for the supply pipe 68 portion pressed by the end portions of these cams. When the cams 162 and 164 are rotated, the end portions (cuts) of the cams 162 and 164 are cut. The tube tube can be pressed at a portion where no notch is formed. Thereby, when the tube tube is pressed by the cam, the inner diameter of the tube tube is narrowed, and the flow rate of the flowing ink can be limited. It should be noted that when the tube tube is pressed, the present invention is not limited to a mode in which the flow rate of the flowing ink is limited, and a configuration in which the ink flow is stopped may be employed.

  FIG. 14 (c) shows a state in which the valve B1 is closed and the valve B2 is opened, but the cams 162 and 164 are shown separated for the sake of explanation. Reference numeral 170 in FIG. 14B is an encoder for detecting the rotational position of the cam.

  According to the valve mechanism having such a configuration, when the motor 160 is driven from the state shown in FIG. 14C and the cams 162 and 164 are rotated in the clockwise direction in FIG. B2 can be sequentially switched between open / close (90 ° rotation from FIG. 14B), close / close (180 ° rotation), and open / open (270 ° rotation). Therefore, with the valve mechanism having such a configuration, it is possible to control opening and closing of two valves by one motor, and it is possible to switch between four modes of valve opening and closing.

  The configuration of the droplet ejecting head shown in the embodiment as described above is not limited to the above embodiment. For example, in FIG. 6, the nozzle plate 78 is formed of a light transmitting member such as polyimide and is provided so as to be able to transmit the inside of the branch channel 62, and an optical sensor is provided on the lower surface of the nozzle plate 78. It is good also as an aspect which detects a bubble. When the optical sensor detects a bubble in the branch channel 62, the recovery process described above is performed. As a result, the generation of bubbles in the branch flow path 62 can be detected immediately, so that the quality of the recorded image can be prevented from being lowered, and unnecessary recovery processing can be eliminated. The common flow channel 60 may be formed of a light transmitting member such as acrylic, and an optical sensor that detects air bubbles in the common flow channel 60 may be provided in the upper portion of the common flow channel 60.

  In this embodiment, a piezoelectric element is used as an actuator for applying pressure (ejection force) to ink in the pressure chamber, and a method of ejecting ink droplets by deformation of the piezoelectric element is employed. However, the present invention is not limited to this, and an actuator having another configuration may be used as long as it is a discharge force applying unit that applies a discharge force to ink.

  Further, in this embodiment mode, an example in which the present invention is applied to a recording head used in an ink jet printer as a liquid droplet ejecting head has been described. The present invention is also applicable to a liquid droplet ejecting head that discharges liquids such as resist and processing liquid to form shapes such as images, circuit wirings, and processing patterns.

1 is a side view showing an ink jet printer to which a liquid droplet ejecting head and a liquid droplet ejecting apparatus according to an embodiment of the present invention are applied. 1 is a plan view of a main part around an image forming unit of an ink jet printer to which a liquid droplet ejecting head and a liquid droplet ejecting apparatus according to an embodiment of the present invention are applied; Plane perspective view showing a configuration of a recording head as a liquid droplet ejecting head according to an embodiment of the present invention and plane perspective view showing another configuration example of a full-line type head FIG. 3 is an enlarged view showing a nozzle arrangement of a recording head as a droplet ejecting head according to an embodiment of the invention FIG. 2 is a perspective plan view showing an ink supply system of a recording head as a liquid droplet ejecting head according to an embodiment of the present invention. Sectional drawing which follows the AA line in FIG. 1 is a perspective view showing an external configuration of a recording head as a liquid droplet ejecting head according to an embodiment of the invention. 1 is a schematic diagram showing an ink supply system of an ink jet printer to which a liquid droplet ejecting head and a liquid droplet ejecting apparatus according to an embodiment of the present invention are applied. FIG. 1 is a control block diagram of an inkjet printer to which a droplet ejecting head and a droplet ejecting apparatus according to an embodiment of the present invention are applied. 6 is a flowchart showing an operation sequence at power-on of an ink jet printer to which the liquid droplet ejecting head and the liquid droplet ejecting apparatus according to the embodiment of the invention are applied. 1 is a flowchart showing an operation sequence during standby of an ink jet printer to which a liquid droplet ejecting head and a liquid droplet ejecting apparatus according to an embodiment of the invention are applied. 6 is a flowchart illustrating an operation sequence when an image is defective in an inkjet printer to which the droplet ejecting head and the droplet ejecting apparatus according to the embodiment of the invention are applied. Chart showing examples of mode combinations 1 is a configuration diagram showing a valve mechanism that is preferably used in an ink jet printer to which a liquid droplet ejecting head and a liquid droplet ejecting apparatus according to an embodiment of the present invention are applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inkjet printer, 12K, 12C, 12M, 12Y, 50 ... Recording head, 16 ... Recording paper, 51 ... Nozzle, 52 ... Pressure chamber, 60 (60A, 60B) ... Common flow path, 62 ... Branch flow path, 64 ... Main supply port, B1, B2 ... Valve, 132 ... System controller

Claims (12)

In a liquid droplet ejecting head provided with a liquid pressurizing unit that two-dimensionally arranges a plurality of liquid chambers in which nozzles for discharging liquid droplets are formed and discharges a predetermined amount of liquid from the nozzles,
At least two main channels provided with channel ports functioning as at least one of the liquid supply port and the liquid discharge port;
A plurality of branch passages that are communicated with the main flow channel and communicated with the liquid chamber and capable of supplying a liquid to each liquid chamber;
The two main channels have the channel ports formed at both ends of each main channel,
The droplet ejecting head, wherein the plurality of branch channels are spanned between the two main channels.   2. The liquid droplet ejecting head according to claim 1, wherein the main flow path and the branch flow path are not formed with terminal portions as flow paths. A liquid droplet ejecting head comprising a plurality of liquid chambers in which nozzles for discharging liquid droplets are formed in a two-dimensional manner, and liquid pressurizing means for discharging a predetermined amount of liquid from the nozzles. Two main channels having a channel port functioning as at least one of a port and a liquid outlet, and are connected to the main channel and to the liquid chamber, and supply liquid to each liquid chamber A plurality of possible branch channels, and a droplet ejecting head in which the channel ports are formed at both ends of the two main channels,
A first valve means provided at one end of the first main flow path of the two main flow paths for opening and closing the flow of the liquid passing through the flow path port;
The liquid that is provided at the end of the second main flow path different from the first main flow path at the end opposite to the position of the first valve means in the first main flow path, and passes through the flow path port. Second valve means for opening and closing the flow of
A droplet ejecting apparatus comprising: valve control means for controlling the first valve means and the second valve means in accordance with an operation mode.   4. The droplet ejecting apparatus according to claim 3, wherein the operation mode includes at least two of a startup mode, a droplet ejection mode, a standby mode, and a recovery mode.   In the start-up mode, the valve control means closes the first valve means and opens the second valve means, or opens the first valve means and closes the second valve means. The droplet ejecting apparatus according to claim 4, further comprising:   5. The droplet ejecting apparatus according to claim 4, wherein in the start-up mode, the valve control means includes a step of closing both the first valve means and the second valve means.   5. The liquid according to claim 4, wherein in the start-up mode, the valve control means includes a step of opening both the first valve means and the second valve means to perform preliminary discharge. Drop ejector.   5. The droplet ejecting apparatus according to claim 4, wherein in the droplet ejecting mode, the valve control means includes a step of opening both the first valve means and the second valve means.   5. The liquid droplet according to claim 4, wherein in the recovery mode, the valve control means includes a step of opening both the first valve means and the second valve means to perform preliminary discharge. Injection device.   The liquid droplet ejecting apparatus according to claim 7 or 9, wherein the liquid is pressurized and supplied by a liquid supply unit connected to the flow path port during the preliminary discharge.   The droplet ejecting apparatus according to claim 3, wherein the valve means is a valve that regulates a flow of liquid. 3. The liquid droplet according to claim 1, wherein the main channel and the branch channel are arranged so as to have substantially rotational symmetry with respect to an arrangement center of the plurality of liquid chambers. Jet head.

Images