Patent Publication Number: US-2016236469-A1

Title: Liquid discharging head, liquid discharging unit, and device to discharge liquid

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is based on and claims priority pursuant to 35 U.S.C. §119 to Japanese Patent Application No. 2015-024867 on Feb. 12, 2015 in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid discharging head, a liquid discharging unit, and a device to discharge liquid. 
     2. Background Art 
     As a liquid discharging head to discharge a liquid, those having two or more heads arranged in the longitudinal direction are known. 
     For example, multiple short heads (head chip) are arranged in the width direction of a recording medium, which is referred to as multi-array heads. 
     When a drive signal is impart to each pressure generator (drive element) corresponding to multiple nozzles in a single head, a configuration to conduct one side supply is known, which provides the drive signal from one side of the multiple pressure generators aligned in the nozzle arrangement direction. 
     In this one-side supply configuration, as the pressure generators are located farther away from the supplying side of the drive signal, the rounding of the waveforms of the drive signal increases. Accordingly, the discharging property of the nozzles changes depending on the positions thereof. 
     For this reason, if multiple heads are arranged side by side, the discharging property changes at joints of adjacent heads in the arrangement direction. As a consequence, the image quality deteriorates at the joint portions. 
     SUMMARY 
     According to the present invention, provided is an improved liquid discharging head which includes a substrate, at least two heads arranged on the substrate in a longitudinal direction of the liquid discharging head. Each of the at least two heads includes a plurality of nozzles configured to discharge a liquid and a plurality of pressure generators corresponding to the plurality of nozzles, wherein a drive signal imparted to the pressure generators is supplied to each of the at least two heads from one side (supplying side) in an arrangement direction of the pressure generators, two adjacent heads of the at least two heads are arranged with the far side of each of the two adjacent heads from the one side placed next to each other or the near side thereof placed next to each other, and the far side of each of the two adjacent heads is mutually connected with each other. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the detailed description when considered in connection with the accompanying drawings in which like reference characters designate like corresponding parts throughout and wherein: 
         FIG. 1  is a schematic planar diagram illustrating a liquid discharging head according to an embodiment of the present disclosure; 
         FIG. 2  is a cross section along the direction (longitudinal direction of liquid chamber) vertical to the nozzle arrangement direction of an example of a head; 
         FIG. 3  is a cross section along the direction (latitudinal direction of liquid chamber) of the nozzle arrangement of the head illustrated in  FIG. 2 ; 
         FIG. 4  is a diagram illustrating a circuit schematic including a head drive controller to drive a liquid discharging head; 
         FIG. 5  is a graph illustrating an example of a drive signal; 
         FIG. 6  is a graph illustrating an example of a drive signal to which rounding occurs to; 
         FIG. 7  is a diagram for use in a description of the relation between the nozzle position and the discharging speed to the supplying side of the drive signal in a head; 
         FIG. 8  is a diagram for use in a description of a first embodiment of the present disclosure; 
         FIG. 9  is a circuit schematic of the equivalence circuit of the first embodiment; 
         FIG. 10  is a diagram for use in a description of the first embodiment. 
         FIG. 11  is a diagram for use in a description of the first embodiment of the present disclosure; 
         FIG. 12  is a schematic diagram illustrating an example of a device to discharge a liquid according to an embodiment of the present disclosure; and 
         FIG. 13  is a diagram illustrating an example of a liquid discharging unit of the device to discharge a liquid illustrated in  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes” and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     In describing example embodiments shown in the drawings, specific terminology is employed for the sake of clarity. However, the present disclosure is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner. 
     In the following description, illustrative embodiments will be described with reference to acts and symbolic representations of operations (e.g., in the form of flowcharts) that may be implemented as program modules or functional processes including routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types and may be implemented using existing hardware at existing network elements or control nodes. Such existing hardware may include one or more Central Processing Units (CPUs), digital signal processors (DSPs), application-specific-integrated-circuits, field programmable gate arrays (FPGAs) computers or the like. These terms in general may be referred to as processors. 
     Unless specifically stated otherwise, or as is apparent from the discussion, terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical, electronic quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
     Preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Although the presently preferred embodiments of the present invention are described with various technically preferred limitations, the scope of the invention should not be construed as limited by the embodiments discussed below. It should not be construed that all of elements of the embodiments discussed below are essential to the invention unless specifically stated as such 
     According to the present disclosure, the deterioration of the image quality at joint portions of head chips is subdued. 
     Embodiments of the present disclosure are described with reference to the accompanying drawings. An embodiment of the liquid discharging head according to the present disclosure is described with reference to  FIG. 1 .  FIG. 1  is a schematic planar diagram illustrating a liquid discharging head. 
     A liquid discharging head  100  includes multiple heads  101  arranged on a substrate  102  along the longitudinal direction, i.e., the nozzle arrangement direction in a zigzag way. 
     Next, an embodiment of the head  101  is described with reference to  FIGS. 2 and 3 .  FIG. 2  is a cross section along the direction (longitudinal direction of liquid chamber) vertical to the nozzle arrangement direction of the head and  FIG. 3  is a cross section along the direction (latitudinal direction of liquid chamber) of the nozzle arrangement of the head. 
     This head  101  includes, for example, a flow path plate  1  configured of two SUS substrates  1 A and  1 B, a vibration plate member  2  jointed with one surface of the flow path plate  1 , and a nozzle plate  3  jointed another surface of the flow path plate  1 . 
     By these, multiple individual liquid chambers  6  serving as individual paths communicating with multiple nozzles  4  to discharge droplets (droplets of liquid) via a path  5  individually, a fluid resistance  7  doubled as a supplying path through which the liquid is supplied to the individual liquid chamber  6 , and a liquid introduction unit  8  communicating with the individual liquid chamber  6  via the fluid resistance  7 . 
     The liquid is supplied to the liquid introduction unit  8  from a common liquid chamber  10  formed on a frame member  17  via a supplying mouth  9  formed on the vibration plate member  2 . 
     The vibration plate member  2  has each vibration area  2   a  constituting the walls corresponding to each individual liquid chamber  6  and an insular convex part  2   b  outside the surface (opposite side of the liquid chamber  6 ) of the vibration area  2   a . The insular convex part  2   b  of the vibration plate member  2  is jointed on the upper surface (jointed surface) of a piezoelectric element  12 A having a pillar-like form of a laminate piezoelectric member  12  serving as pressure generator (drive element, actuator) to transform the vibration area  2   a . In addition, the opposite surface of the laminate piezoelectric member  12  is jointed with a base plate  13 . 
     The piezoelectric member  12  is formed by alternately laminating a piezoelectric layer  21  and inside electrodes  22 A and  22 B. Each of the inside electrodes  22 A and  22 B is drawn to the end surface, i.e., the lateral side substantially vertical to the vibration plate member  2  of the piezoelectric member  12  and connected to end surface electrodes (external electrodes)  23  and  24  formed on the lateral side. A displacement in the lamination direction occurs by applying a voltage between the end surface electrodes (exterior electrodes)  23  and  24 . The exterior electrodes  23  is set as individual exterior electrode (individual electrode) and the exterior electrode  24  is used as common exterior electrode (common electrode). 
     This piezoelectric member  12  is processed by half cut dicing to form grooves  31  (illustrated in  FIG. 3 ) and a particular number of piezoelectric elements (piezoelectric pillar)  12 A and  12 B having a pillar-like form are formed on the piezoelectric member  12  in a pectinate manner spaced a predetermined distance therebetween. 
     Although the piezoelectric elements  12 A and  12 B of the piezoelectric element  12  are the same, the piezoelectric element  12 A is driven by a drive waveform (drive signal) and the piezoelectric element  12 B is not driven by a drive waveform but simply used as a supporting pillar. In addition, the piezoelectric element  12 B at the end of the piezoelectric member  12  is set as a piezoelectric element  12 Ba, which has a greater breadth to draw the common electrode to the outside, and each of the inside electrodes  22 A and  22 B is provided to each end. 
     In addition, a flexible printed circuit (FPC)  15  serving as flexible wiring board to transmit a drive signal imparted to the piezoelectric element  12 A is connected with the piezoelectric member  12 . 
     The FPC  15  has an individual electrode wiring connected with the individual exterior electrode  23  of the piezoelectric element  12 A to transmit a drive signal and a common electrode wiring connected with a common drawing-out electrode connected with the common electrode  24  of the multiple piezoelectric elements  12 A drawn out to the piezoelectric element  12 Ba at the end portion. 
     This FPC  15  includes a drive IC (driver IC)  16  to output a drive signal to the piezoelectric element  12 A in accordance with image data. 
     On the nozzle plate  3 , the nozzle  4  having a diameter of from 10 μm to 35 μm corresponding to each individual liquid chamber  6  is formed and jointed with the flow path plate  1  with an adhesive. A liquid repellent layer is provided to the discharging surface (surface along the discharging direction, opposite side to the liquid chamber  6 ) of the nozzle plate  3 . 
     Furthermore, the frame member  17  made of, for example, an epoxy-based resin or polyphenylene sulfite by injection molding is jointed to the outer circumference of the piezoelectric actuator including these piezoelectric member  12 , the base plate  13 , the FPC  15 , etc. 
     The frame member  17  includes the above-mentioned common liquid chamber  10 . Moreover, a supplying mouth  19  to supply a liquid from outside to the common liquid chamber  10  is formed on the frame member  17  and the supplying mouth  19  is connected with a liquid supply source such as a sub-tank or a liquid tank. 
     In the head  101  having such a configuration, the piezoelectric element  12 A contracts by, for example, lowering the voltage applied to the piezoelectric element  12 A of the piezoelectric element  12  from a reference voltage. For this reason, the vibration area  2   a  of the vibration plate member  2  deforms, thereby inflating the volume of the individual liquid chamber  6 . As a result, the liquid flows into the individual liquid chamber  6 . 
     Thereafter, the piezoelectric element  12 A is elongated in the lamination direction by raising the voltage applied to the piezoelectric element  12 A of the piezoelectric element  12  to transform the vibration area  2   a  of the vibration plate member  2  toward the nozzle  4  direction, thereby contracting the volume of the individual liquid chamber  6 . For this reason, the liquid in the liquid chamber  6  is pressurized so that the liquid is discharged through the nozzle  4 . 
     Thereafter, the voltage applied to the piezoelectric element  12 A of the piezoelectric element  12  is caused to be back to the reference voltage. Accordingly, the vibration area  2   a  of the vibration plate member  2  is back to the initial position so that the individual liquid chamber  6  inflates, which generates a negative pressure. At this point in time, the ink is supplied from the common liquid chamber  10  to the individual liquid chamber  6 . After the vibration of the meniscus surface of the nozzle  4  decays and is stabilized, the system starts operations to discharge the next droplet. 
     Next, a circuit schematic including a head drive controller to drive a liquid discharging head is described with reference to  FIG. 4 .  FIG. 4  is a circuit schematic illustrating a circuit including a head drive controller of a single head. 
     As described above, the piezoelectric elements  12 A (piezoelectric element PZT in this case) serving as multiple pressure generators corresponding to the nozzles  4  are arranged in a single head  101 . 
     On the other hand, a drive signal generating circuit (drive signal source)  601  generates and outputs, for example, a drive signal (drive waveform) as illustrated in  FIG. 5 . 
     The drive signal generated by this drive signal generating circuit  601  is supplied to the drive IC  16  in the head  101  via a wiring member such as the FPC  15  and thereafter imparted to each piezoelectric element PZT via a switch SW serving as a selector configured of analogue switches included in the drive IC  16 . 
     The waveform selection control circuit  602  outputs a signal to control on and off of the switch SW in accordance with image data. When the switch SW is on, the drive signal is input into the piezoelectric element PZT. 
     The supply (power supply) of the drive signal to the multiple piezoelectric elements PZT is configured to be a one-side supply, i.e., supply from one side (supplying side) of the arrangement direction of the piezoelectric elements. 
     Each of the lines of the multiple piezoelectric elements PZT and the switches SW aligned in the nozzle arrangement direction is either on the near or far side about the supplying side of the drive signal. 
     The supply circuit to supply the drive signal supplied from the drive signal generating circuit  601  to each switch SW and piezoelectric element PZT is a RC low-pass filter (LPF) circuit configured of a synthesized resistance component R of the inside wiring in the drive IC  16 , a resistance component R 1  of the common electrode wiring, and a capacitor component C of the piezoelectric element PZT when the switch SW is on. 
     The high frequency component of the drive signal is removed when the drive signal passes through this LPF. Therefore, the number of LPF&#39;s through which the drive signal passes increases as the line is situated farther from the supplying side of the drive signal. Consequently, rounding occurs to the waveform of the drive signal as illustrated in  FIG. 6 . In particular, as the number of the piezoelectric elements PZT that are driven at the same time increases, the number of LPF&#39;s increases, so that the amount of rounding of the drive signal increases. 
     Due to this rounding of the drive signal, discharging speed Vi becomes slower. For this reason, as illustrated in  FIG. 7 , the discharging speed Vi slows down from the nozzles located on the near side to the supplying side (power supplying side to the head) of a drive signal towards the nozzles located on the far side (opposite side to the supplying side). 
     In this liquid discharging head  100 , as illustrated in  FIG. 1 , two adjacent heads (first and second heads)  101  are arranged in the head arrangement direction in such a manner that the far sides from the supplying sides (which is connected to the drive signal generating circuit  601  via the wiring member such as the FPC  15 ) of a drive signal are adjacent to each other. The two adjacent heads  101  may also be arranged in such a manner that the near sides from the supplying sides of a drive signal are next to each other. 
     That is, in the two adjacent heads  101 , the discharging speed Vj changes in the reverse direction in the head arrangement direction. Therefore, for example, if the change amount of the discharging speed Vj of each head  101  is assumed to be substantially the same, the discharging speed Vj of the entire of the liquid discharging heads  100  is that the maximum change amount of the discharging speed Vj of the individual heads  101  is within the change amount of the discharging speed Vj of a single head  101 . 
     Since the discharging speed Vj of the adjacent heads  101  and that at the joint portion thereof are almost the same, streaks stemming from the difference between the discharging speeds Vj are not highly visible. That is, the degradation of the image density at the joint portion is lessened, thereby improving the image quality. 
     Next, the first embodiment of the present disclosure is described with reference to  FIG. 8  and  FIG. 9 .  FIG. 8  is a diagram for use in a description of the first embodiment and  FIG. 9  is a circuit schematic of the equivalence circuit thereof. 
     The two adjacent heads (first and second heads)  101 A and  101 B have a common electrode wiring pattern  201  with which the common electrode  24  of each piezoelectric element PZT is connected along the arrangement direction of the multiple piezoelectric elements PZT. In addition, the individual electrodes  23  of each piezoelectric element PZT is connected with the switch SW serving as selector in the drive IC  16 . The multiple switches SW are arranged in the arrangement direction of the piezoelectric elements PZT. 
     A supply wiring  161  of a drive signal from the drive signal generating circuit  601  is connected on one side (end) of the common electrode wiring pattern  201 . In addition, a supply wiring  162  of a drive signal from the drive signal generating circuit  601  is connected with the switch SW on one side (end) of the multiple switches SW of the drive IC  16 . 
     The two adjacent heads  101 A and  101 B are arranged with the far sides thereof from the supplying sides of the drive signal adjacent to each other. 
     The two adjacent heads  101 A and  101 B are mutually connected through the far sides of the common electrode wiring patterns  201  by a cross-linking wiring  202 . Part of the cross-linking wiring  202  is configured of an inside wiring  202   a  of the heads  101 A and  101 B. 
     In addition, of the multiple switches SW constituting a switch group  16   a  of the two heads  101 A and  101 B, the switches SW located on the far sides from the supplying sides of the drive signal are mutually connected with each other on the opposite sides of the side (first side) connected with the piezoelectric elements PZT by a cross-linking wiring  203 . The switch group  16   a  is included in the drive IC  16 . 
     As illustrated in  FIG. 9 , the far side from the supplying side of the drive signal of the head  101 A on the common electrode wiring pattern  201  and the far side from the supplying side of the drive signal of the head  101 B on the common electrode wiring pattern  201  are connected via a cross-linking resistance R 202  of the cross-linking wiring  202 . 
     In addition, the opposite side of the side connected with the piezoelectric element PZT of the switch SW located on the far side from the supplying side of the drive signal of the head  101 A is connected with the side connected with the piezoelectric element PZT of the switch SW located on the far side of the supplying side of the drive signal of the head  101 B via the cross-linking resistance R 203  of the cross-linking wiring  203 . 
     Next, the working of the embodiment having such a configuration is described with reference to  FIG. 10 .  FIG. 10  is a diagram for use in a description of this embodiment. 
     In the two heads  101 A and  101 B, the number of nozzles to discharge a liquid at the same time (This is referred to as drive channel) may be different. For example, as illustrated in  FIG. 10 , there may be a case in which the number of drive channels at the same time of the head  101 A is small while the number of drive channels at the same time of the head  101 B is large or vice versa. 
     Unlike this embodiment, if no connection is made by the cross-linking wirings  202  and  203  (this is a “Comparative Embodiment”), the lowering amount of the discharging speed Vj on the far side from the supplying side of a drive signal varies between the head  101 A and the head  101 B as illustrated in the broken lines in  FIG. 10 . 
     That is, if the far sides relative to the supplying sides of a drive signal are arranged next to each other but the number of drive channels is different, the discharging speed Vj at the joint portion of the adjacent two heads varies, so that the image quality deteriorates at the joint portion. 
     Taking account into this, this embodiment has a configuration in which the far ends relative to the supplying side of a drive signal of the two heads are mutually connected. 
     For this reason, for example, when the number of drive channels of the head  101 A is small while the number of drive channels of the head  101 B is large, the power is supplied to the piezoelectric element PZT on the far side from the supplying side of the head  101 B via the wiring of the drive signal of the head  101 A and the cross-linking wirings  202  and  203 . 
     Therefore, the current through the head  101 A increases, so that the discharging speed Vj in the head  101 A lowers greatly. 
     As a result, as illustrated in the solid line in  FIG. 10 , the discharging speed Vj in the head  101 A lowers greatly and becomes almost the same as that of the head  101 B, so that the difference between both discharging speeds Vj is small at the joint portion of the two heads  101 A and  101 B. 
     For this reason, the change in the image quality is not highly visible, thereby improving the entire print quality. 
     Next, the second embodiment of the present disclosure is described with reference to  FIG. 12 .  FIG. 12  is a diagram for use in a description of the second embodiment of the present disclosure. 
     In this embodiment, the two heads  101 A and  101 B are arranged in such a manner that the near sides thereof from the supplying sides of a drive signal are next to each other. 
     The other configuration is the same as those in the first embodiment. 
     The same working in such a configuration is obtained as in the first embodiment. 
     In addition, in each embodiment, both the common electrode wiring pattern and the switches are connected on the far sides from the supplying sides of a drive signal. However, it is also suitable to have a configuration in which one of the common electrode wiring pattern and the switch is mutually connected on the far sides from the supplying side of the drive signal. 
     One embodiment of the device to discharge a liquid of the present disclosure is described with reference to  FIG. 12  and  FIG. 13 .  FIG. 12  is a diagram illustrating the device and  FIG. 13  is a planar view of the liquid discharging unit of the device. 
     The device to discharge the liquid is a line-type image forming apparatus. A sheet  400  serving as a recording medium loaded in a sheet feeding tray  401  is transferred by a feeding roller  402  along the transfer path indicated by the doted lines. The sheet  400  transferred to the transfer path is transferred to a belt transfer unit  404  via a pair of timing adjusting and skew correcting rollers (i.e., registration rollers)  403 . 
     The belt transfer unit  404  includes a transfer roller  405  driven on a timing, a tension roller  406 , and a transfer belt  407  having an endless form stretched between the transfer roller  405  and the tension roller  406 . 
     To hold the sheet  400  by the transfer belt  407  of the belt transfer unit  404 , it is possible to use a device utilizing adsorption such as electrostatic adsorption and air adsorption and other known devices. 
     The sheet  400  is transferred by the belt transfer unit  404  while facing a liquid discharging unit  300  and each head  101  of each liquid discharging head  311  of the liquid discharging unit  300  is driven in accordance with image data to discharge liquid, thereby forming an image. 
     The liquid discharging unit  300  is configured of the multiple liquid discharging heads  100  of the first embodiment and includes a liquid discharging head  311 Y, a liquid discharging head  311 M, a liquid discharging head  311 C, and a liquid discharging head  311 K to discharge the liquid of yellow (Y), magenta (M), cyan (C), and black (K) as illustrated in  FIG. 13 . 
     The sheet  400  on which the image is formed by the liquid discharging unit  300  is transferred to a de-curling unit  409  where the sheet  400  is de-curled (curling correction). 
     The sheet  400  that has passed the de-curling unit  409  is ejected to an ejection roller  412  by a separation claw  410  via a transfer path  411  if the sheet  400  is ejected with no further processing. 
     In addition, when the sheet  400  is reversed before ejection or subject to printing in the opposite surface (duplex printing), the separation claw  410  is switched counterclockwise from the position illustrated in  FIG. 12  and the sheet  400  passes through a transfer path  413  via a guide  414  to a hitting roller  415 . The sheet  400  sent to the hitting roller  415  is transferred in the reverse direction by the hitting roller  415  in which the rotation direction is changed. 
     The sheet  400  that has passed the de-curling unit  409  is ejected to an ejection roller  412  via a second separation claw  416  and a transfer path  417  if the sheet  400  is ejected with no further processing. 
     In addition, in the case of duplex printing, the sheet  400  transferred in the reverse direction by the hitting roller  415  passes through a transfer path  419  via the second separation claw  416  switched counterclockwise from the position illustrated in  FIG. 12  and a duplex reversing roller  418  to a pair of registration rollers  403 . 
     In addition, to maintain and recover the performance of each head  101  of the liquid discharging unit  300 , a maintenance and recover unit  408  is provided. The maintenance and recovery unit  408  includes a cap  420  to cap the nozzle surface of each head  101 , a suction pump connected with the cap  420 , and a wiper  422  to wipe ink remaining on the head when the ink is suctioned in the cap  420 . 
     During maintenance and recovery, the liquid discharging unit  300  elevates and the maintenance and recovery unit  408  moves below each head  101  of the liquid discharging unit  300  to conduct maintenance and recovery. In addition, the cap  420  of the maintenance and recovery unit  408  serve as moisturizing cap to maintain the moisture of each head  101  of the liquid discharging unit  300  during stand-by. During non-printing, the liquid discharging unit  300  elevates and the maintenance and recovery unit  408  moves below the liquid discharging unit  300  to conduct moisturizing capping. 
     By providing the liquid discharging head or the liquid discharging unit including the liquid discharging head relating to the present disclosure, the deterioration of the image quality in the head arrangement direction is subdued to form quality images. 
     In the present disclosure, the device to discharge a liquid represents a device to discharge a liquid to a medium (object) to which the liquid is attachable. 
     The device to discharge a liquid may include not only a portion discharging a liquid but also a unit relating to feeding, transferring, ejecting recording media, and other devices referred to as a pre-processing device, a post-processing device, etc. 
     In addition, the device to discharge a liquid includes typical devices such as a recording device, a printing device, an image forming apparatus, a droplet discharging device, a liquid discharging device, a process fluid applicator, and a 3D modeling device. 
     In addition, the device to discharge a liquid is not limited only to a device which can produce meaningful and visible images such as texts and figures by a liquid attached to what the liquid is attachable. For example, the device to discharge a liquid may form meaningless patterns or 3D images. 
     What the liquid is attachable means what the liquid can be attached even temporarily. When alternative terms such as sheets, media, recording media, recording sheets, recording paper, powder layer are used instead of the wording of what the liquid is attachable, the wording includes what any kinds of liquids can be attached unless otherwise specified. 
     Specific examples of the materials of what a liquid can be attached include anything to which a liquid can be attached even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, and ceramics. 
     In addition, the liquid includes ink, process fluid, DNA sample, resists, pattern materials, and binding agents. 
     The device to discharge a liquid includes both a serial type device in which the liquid discharging head is caused to move and a line type device in which the liquid discharging head is not caused to move, unless otherwise specified. 
     The liquid discharging unit represents a part integrated with a portion causing to discharge a liquid. For example, the liquid discharging unit includes a combination of multiple liquid discharging heads and a combination of the liquid discharging head and at least one of a head tank, a carriage, a supplying mechanism, a maintenance mechanism, and the main scanning moving mechanism. 
     For example, the liquid discharging unit includes a part in which a liquid discharging head is integrated with a head tank, a part in which a liquid discharging head is integrated with a carriage, and a part in which a liquid discharging head is integrated with a head tank and a carriage. 
     Also, it is possible to add a filter unit to those. 
     In addition, the liquid discharging unit includes a part in which a liquid discharging head is integrated with a maintenance mechanism, a part in which a liquid discharging head is integrated with a maintenance mechanism and a main scanning moving mechanism, and a part in which a liquid discharging head is integrated with a main scanning moving mechanism and a supplying mechanism in a serial type device. 
     The main scanning mechanism is configured by combining a carriage, a guiding member to guide the carriage, or a combination of those with a drive source and a moving mechanism of the carriage. The supplying mechanism includes a mounting unit to which a main tank is mounted, a tube, a head tank, etc. The maintenance mechanism is a combination of at least two of a cap, a wiper, a suction device such as a suction pump connected with the cap, and a dummy discharging receiver. 
     Furthermore, the liquid discharging unit may have a configuration in which the mechanism to transfer what a liquid is attached from the mechanism described in the embodiments. 
     In addition, the liquid discharging head has no specific limit to the pressure generating device used therein. For example, other than the piezoelectric actuator in the embodiments described above, it is possible to use a thermal actuator using the thermoelectric conversion element such as a heat element and an electrostatic actuator including a vibration plate and a counter electrode. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the disclosure of the present invention may be practiced otherwise than as specifically described herein. For example, elements and/or features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims. 
     Each of the functions of the described embodiments may be implemented by one or more processing circuits or circuitry. Processing circuitry includes a programmed processor, as a processor includes circuitry. A processing circuit also includes devices such as an application specific integrated circuit (ASIC) and conventional circuit components arranged to perform the recited functions. 
     The present invention can be implemented in any convenient form, for example using dedicated hardware, or a mixture of dedicated hardware and software. The present invention may be implemented as computer software implemented by one or more networked processing apparatuses. The network can comprise any conventional terrestrial or wireless communications network, such as the Internet. The processing apparatuses can compromise any suitably programmed apparatuses such as a general purpose computer, personal digital assistant, mobile telephone (such as a WAP or 3G-compliant phone) and so on. Since the present invention can be implemented as software, each and every aspect of the present invention thus encompasses computer software implementable on a programmable device. The computer software can be provided to the programmable device using any storage medium for storing processor readable code such as a floppy disk, hard disk, CD ROM, magnetic tape device or solid state memory device. 
     The hardware platform includes any desired kind of hardware resources including, for example, a central processing unit (CPU), a random access memory (RAM), and a hard disk drive (HDD). The CPU may be implemented by any desired kind of any desired number of processor. The RAM may be implemented by any desired kind of volatile or non-volatile memory. The HDD may be implemented by any desired kind of non-volatile memory capable of storing a large amount of data. The hardware resources may additionally include an input device, an output device, or a network device, depending on the type of the apparatus. Alternatively, the HDD may be provided outside of the apparatus as long as the HDD is accessible. In this example, the CPU, such as a cache memory of the CPU, and the RAM may function as a physical memory or a primary memory of the apparatus, while the HDD may function as a secondary memory of the apparatus.