JP5050961B2 - Liquid ejecting drive apparatus, liquid ejecting head, and liquid ejecting apparatus - Google Patents

Description

  The present invention relates to a liquid ejecting drive apparatus that drives a liquid ejecting head that ejects liquid from a nozzle opening, a liquid ejecting head including the same, and a liquid ejecting apparatus.

  An ink jet recording apparatus such as an ink jet printer or plotter has an ink jet recording head capable of ejecting ink stored in an ink storage means such as an ink cartridge or an ink tank as ink droplets.

  Here, the ink jet recording head includes a pressure generating chamber that communicates with the nozzle openings, a reservoir that is a common liquid chamber that communicates with a plurality of pressure generating chambers, and a pressure change that occurs in the pressure generating chambers from the nozzle openings. Pressure generating means for discharging droplets. Examples of pressure generating means mounted on the ink jet recording head include longitudinal vibration type piezoelectric elements, flexural vibration type piezoelectric elements, those using electrostatic force, and those using heating elements.

  When droplets are ejected to such an ink jet recording head, the ejection characteristics change, such as the ejection speed and weight of the ejected droplets change, due to the difference in the viscosity of the droplets based on temperature changes. There is a problem of doing. In addition, there is a problem in that the solvent of the droplets evaporates to greatly change the viscosity, and the discharge characteristics similarly change. Furthermore, depending on the purpose of droplet ejection, it is necessary to eject a very high-viscosity liquid. In such a case, ejection characteristics similar to those in a normal case are required.

  For this reason, a technique has been proposed in which a temperature detection sensor is provided to finely adjust the drive waveform of the ink jet head in accordance with a temperature change, and the ink droplet weight is stably ejected (see Patent Document 1). In this technique, the drive voltage is adjusted so as to decrease by the amount of the decrease in viscosity based on the temperature increase.

  In addition, a technique for providing a viscosity measuring unit and determining a drive voltage waveform based on a viscosity measurement result has been proposed (see Patent Document 2). This technology adjusts the width of the negative gradient portion, which is a contraction element for discharging the drive waveform, to a predetermined value as the viscosity increases, and increases the width as the ink viscosity decreases. This prevents the discharge speed from increasing. In this technique, since the increase in viscosity due to solvent evaporation is a problem, when the viscosity increases, control is performed to reduce the discharge amount by reducing the drive voltage so that the weight after drying becomes constant. is there.

  Furthermore, there has been proposed a device in which a hold element or an expansion element is temporarily provided in the middle of the contraction element of the drive waveform so as to eject minute dots (for example, see Patent Document 3 or 4).

JP 7-148240 A JP 2006-297176 A JP 2006-306076 A JP 2001-150672 A

  However, in the techniques of Patent Documents 1 and 2 described above, the drive waveform is adjusted in accordance with the change in viscosity. However, particularly when a liquid having a high viscosity, for example, a high viscosity of 10 m · Pa or more is discharged, the discharge characteristics. Cannot be maintained, and high-frequency printing becomes difficult. Further, when developing a head that discharges a high-viscosity liquid, a liquid discharge head that can stably discharge a wide range of liquids from low viscosity to high viscosity is desired instead of a dedicated head for high viscosity.

  In addition, when ejecting micro dots using the drive waveforms shown in Patent Documents 3 and 4, it is difficult to form micro dots with high viscosity ink because the viscosity of the ink is not particularly taken into consideration. There's a problem.

  Such a problem exists not only in the ink jet recording apparatus but also in a liquid ejecting apparatus that ejects liquid other than ink.

  SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a liquid jet driving device capable of stably performing high-frequency ejection of minute dots when discharging liquid from low viscosity to high viscosity, and a liquid jet head and a liquid jet device including the liquid jet driving device. The purpose is to provide.

An aspect of the present invention that solves the above-described problem is a liquid ejection that drives a liquid ejection head that includes a pressure generation chamber that communicates with a nozzle opening that discharges liquid, and a pressure generation unit that causes a pressure change in the pressure generation chamber. A drive device, a discharge expansion element for expanding the pressure generation chamber; a discharge hold element for maintaining an expanded state of the pressure generation chamber; and the pressure generation for discharging the droplet from the nozzle opening. Drive means for supplying a series of drive signals including discharge pulses including the discharge contraction elements for contracting the chambers in this order to the pressure generating means; and viscosity information acquisition means for acquiring viscosity information of the liquid to be discharged. The discharge contraction element of the discharge pulse includes an initial contraction element that contracts the pressure generation chamber, a hold element that maintains a contraction state by the initial contraction element, and the initial contraction And a late contraction element that further contracts the pressure generating chamber from the element, and the drive means can supply a plurality of discharge pulses having different times of the hold element of the discharge pulse, and the viscosity information acquisition means acquires Based on the viscosity information, the higher the viscosity information is, the longer the hold element supplies a drive signal including a discharge pulse having a relatively long time, and the lower the viscosity information is, the higher the hold information is. In the liquid jet driving device, a driving signal including an ejection pulse having a relatively short element time is supplied.
In this aspect, as the liquid viscosity is relatively high, a drive signal including an ejection pulse having a relatively long hold element time is supplied, and as the liquid viscosity is relatively low, the hold element time is long. By supplying a drive signal including a relatively short ejection pulse, high-frequency ejection can be stably performed from high viscosity to low viscosity.

  Here, the hold element suppresses vibration in the pressure generating chamber before the liquid is discharged. According to this, the higher the viscosity of the liquid, the slower the return of the meniscus, and the lower the viscosity of the liquid, the faster the return of the meniscus, so the time of the hold element is changed according to the viscosity By doing so, it is possible to cause the vibration control action to function optimally and to discharge micro dots stably.

  The discharge contraction element includes a first contraction element that contracts the pressure generation chamber, a first hold element that maintains a contraction state of the pressure generation chamber by the first contraction element, and the first contraction element. A first expansion element that expands the pressure generation chamber contracted by the contraction element, the initial contraction element that contracts the pressure generation chamber expanded by the first expansion element, the hold element, and the late contraction element It is preferable to comprise. According to this, even when fine dots are ejected, high-frequency ejection can be performed stably regardless of the viscosity of the liquid.

  The viscosity information is preferably based on the type of liquid to be discharged. According to this, regardless of whether the liquid to be discharged has a high viscosity or a low viscosity, the liquid can be driven with a drive signal corresponding to the viscosity.

  The viscosity information is preferably based on the environmental temperature or the temperature of the liquid to be discharged. According to this, it can drive with the optimal drive signal according to the viscosity change of the liquid based on a temperature change.

  Furthermore, another aspect of the present invention includes the liquid jet driving device according to the above aspect, a pressure generation chamber that communicates with a nozzle opening that discharges liquid, and a pressure generation unit that causes a pressure change in the pressure generation chamber. The liquid ejecting head is characterized by the above.

  In this aspect, as the liquid viscosity is relatively high, a drive signal including an ejection pulse having a relatively long hold element time is supplied, and as the liquid viscosity is relatively low, the hold element time is long. By supplying a drive signal including a relatively short ejection pulse, a liquid ejecting head capable of performing high-frequency ejection stably from high viscosity to low viscosity can be obtained.

  Furthermore, another aspect of the present invention includes the liquid jet driving apparatus according to the above aspect, a pressure generation chamber communicating with a nozzle opening for discharging liquid, and a pressure generation unit that causes a pressure change in the pressure generation chamber. The liquid ejecting apparatus includes a liquid ejecting head.

  In this aspect, as the liquid viscosity is relatively high, a drive signal including an ejection pulse having a relatively long hold element time is supplied, and as the liquid viscosity is relatively low, the hold element time is long. By supplying a drive signal including a relatively short ejection pulse, a liquid ejecting apparatus capable of performing high-frequency ejection stably from high viscosity to low viscosity can be obtained.

  In addition, it is preferable that the liquid ejecting head includes a supply unit that supplies a liquid having a viscosity in a range of 6 m · Pas to 20 m · Pas at normal temperature. According to this, stable discharge can be performed even when a liquid having a viscosity at room temperature in the range of 6 m · Pas to 20 m · Pas is used.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is a schematic perspective view of an ink jet recording apparatus which is an example of a liquid ejecting apparatus according to an embodiment of the invention.

  The liquid ejecting apparatus of the present embodiment is, for example, an ink jet recording apparatus. As shown in FIG. 1, recording head units 1A and 1B each having an ink jet recording head described later in detail apply ink to the ink jet recording head. Ink cartridges 2A and 2B constituting supply means for supply are detachably provided, and a carriage 3 on which the recording head units 1A and 1B are mounted is provided on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. It has been. The recording head units 1A and 1B eject a black ink composition and a color ink composition, respectively.

  A drive motor 6 is provided in the vicinity of one end of the carriage shaft 5, and a first pulley 6 a having a groove on the outer periphery is provided at the tip of the shaft of the drive motor 6. Further, in the vicinity of the other end portion of the carriage shaft 5, a second pulley 6b corresponding to the first pulley 6a of the drive motor 6 is rotatably provided, and these first pulley 6a and second pulley are provided. A timing belt 7 made of an elastic member such as rubber is hung between the belt 6b.

  Then, the driving force of the driving motor 6 is transmitted to the carriage 3 via the timing belt 7, so that the carriage 3 on which the recording head units 1 A and 1 B are mounted is moved along the carriage shaft 5. On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage 3. The platen 8 can be rotated by a driving force of a paper feed motor (not shown), and a recording sheet S that is a recording medium such as paper fed by a paper feed roller is wound around the platen 8 and conveyed. It has become so.

  Here, an ink jet recording head mounted on the ink jet recording apparatus I as described above will be described. FIG. 2 is a cross-sectional view showing an example of an ink jet recording head according to Embodiment 1 of the present invention.

  An ink jet recording head 10 shown in FIG. 2 is a type having a longitudinal vibration type piezoelectric element, and a plurality of pressure generating chambers 12 are arranged in parallel on a flow path substrate 11, Sealed by a nozzle plate 14 having a nozzle opening 13 corresponding to the pressure generating chamber 12 and a vibration plate 15. In addition, the flow path substrate 11 is provided with a reservoir 17 that communicates with each pressure generation chamber 12 via an ink supply port 16 and serves as a common ink chamber for the plurality of pressure generation chambers 12. Is connected to an ink cartridge (not shown).

  On the other hand, on the side opposite to the pressure generation chamber 12 of the diaphragm 15, the tip of the piezoelectric element 18 is provided in contact with a region corresponding to each pressure generation chamber 12. These piezoelectric elements 18 are laminated by sandwiching piezoelectric materials 19 and electrode forming materials 20 and 21 vertically in a sandwich shape, and an inactive region that does not contribute to vibration is fixed to a fixed substrate 22.

  In the ink jet recording head 10 configured as described above, ink is supplied to the reservoir 17 via the ink flow path communicating with the ink cartridge, and is distributed to each pressure generating chamber 12 via the ink supply port 16. Actually, the piezoelectric element 18 is contracted by applying a voltage to the piezoelectric element 18. As a result, the diaphragm 15 is deformed together with the piezoelectric element 18 (upwardly in the drawing), the volume of the pressure generating chamber 12 is expanded, and ink is drawn into the pressure generating chamber 12. Then, after filling the inside up to the nozzle opening 13 with ink and then releasing the voltage applied to the electrode forming materials 20 and 21 of the piezoelectric element 18 in accordance with the recording signal from the drive circuit, the piezoelectric element 18 is expanded. To return to the original state. As a result, the vibration plate 15 is also displaced to return to the original state, so that the pressure generating chamber 12 is contracted, the internal pressure is increased, and an ink droplet is ejected from the nozzle opening 13. That is, in the present embodiment, the longitudinal vibration type piezoelectric element 18 is provided as a pressure generating means for causing a pressure change in the pressure generating chamber 12.

  FIG. 3 is a block diagram showing a control configuration of the ink jet recording apparatus. Here, with reference to FIG. 3, the control of the ink jet recording apparatus of the present embodiment will be described. As shown in FIG. 3, the ink jet recording apparatus of the present embodiment is roughly configured by a printer controller 111 and a print engine 112. The printer controller 111 includes an external interface 113 (hereinafter referred to as an external I / F 113), a RAM 114 that temporarily stores various data, a ROM 115 that stores a control program, a control unit 116 that includes a CPU, and the like. And an oscillation circuit 117 that generates a clock signal, a viscosity information storage unit 118, a drive signal generation circuit 119 that generates a drive signal to be supplied to the ink jet recording head 10, and a development based on the drive signal and print data. An internal interface 120 (hereinafter referred to as an internal I / F 120) that transmits dot pattern data (bitmap data) or the like to the print engine 112 is provided.

  The external I / F 113 receives print data including, for example, a character code, a graphic function, image data, and the like from a host computer (not shown). Further, a busy signal (BUSY) and an acknowledge signal (ACK) are output to the host computer or the like through the external I / F 113. The RAM 114 functions as a reception buffer 121, an intermediate buffer 122, an output buffer 123, and a work memory (not shown). The reception buffer 121 temporarily stores the print data received by the external I / F 113, the intermediate buffer 122 stores the intermediate code data converted by the control unit 116, and the output buffer 123 stores the dot pattern data. . This dot pattern data is constituted by print data obtained by decoding (translating) gradation data.

  The ROM 115 stores font data, graphic functions, etc. in addition to a control program (control routine) for performing various data processing.

  The control unit 116 reads the print data in the reception buffer 121 and stores the intermediate code data obtained by converting the print data in the intermediate buffer 122. Further, the intermediate code data read from the intermediate buffer 122 is analyzed, and the intermediate code data is developed into dot pattern data by referring to the font data and graphic functions stored in the ROM 115. Then, the control unit 116 stores the developed dot pattern data in the output buffer 123 after performing necessary decoration processing. Further, the control unit 116 also functions as a waveform setting unit, and controls the drive signal generation circuit 119 to set the waveform shape of the drive signal generated from the drive signal generation circuit 119. The control unit 116 constitutes drive means of the present invention together with a drive circuit (not shown) described later. In addition, the liquid jet driving device that drives the ink jet recording head 10 may be any device that includes at least the driving unit. In the present embodiment, the liquid jet driving device is illustrated as including the printer controller 111.

  The viscosity information storage unit 118 is a non-volatile storage element that can retain stored contents even when the power supply to the printer is cut off. For example, it is configured by an EEPROM, a flash RAM, or a RAM connected to a backup power source. In the present embodiment, the viscosity information storage unit 118 functions as a viscosity information acquisition unit, details of which will be described later. In the viscosity information storage unit 118, waveform information of an ejection pulse, for example, for ejection, in relation to the viscosity range. Information on the time of the hold element provided in the contraction element is stored. In addition, when the viscosity of the ink to be used is determined in advance, the viscosity is stored, and the shape of the ejection pulse to be used is determined according to this viscosity.

  If dot pattern data corresponding to one line of the ink jet recording head 10 is obtained, the dot pattern data for one line is output to the ink jet recording head 10 through the internal I / F 120. When dot pattern data for one line is output from the output buffer 123, the developed intermediate code data is erased from the intermediate buffer 122, and the development process for the next intermediate code data is performed.

  The print engine 112 includes the ink jet recording head 10, a paper feed mechanism 124, and a carriage mechanism 125. The paper feeding mechanism 124 includes a paper feeding motor and a platen 8 and the like, and sequentially feeds a print storage medium such as recording paper in conjunction with the recording operation of the ink jet recording head 10. That is, the paper feed mechanism 124 relatively moves the print storage medium in the sub-scanning direction.

  The carriage mechanism 125 includes a carriage 3 on which the ink jet recording head 10 can be mounted and a carriage drive unit that causes the carriage 3 to travel along the main scanning direction. The head 10 is moved in the main scanning direction. Note that the carriage drive unit includes the drive motor 6 and the timing belt 7 as described above.

  The ink jet recording head 10 has a large number of nozzle openings 13 along the sub-scanning direction, and ejects droplets from the nozzle openings 13 at a timing defined by dot pattern data or the like. The piezoelectric element 18 of the ink jet recording head 10 is supplied with an electrical signal such as a driving signal (COM) or recording data (SI) described later via an external wiring (not shown). In the printer controller 111 and the print engine 112 configured as described above, the printer controller 111 and a latch 132 that selectively inputs a drive signal having a predetermined drive waveform output from the drive signal generation circuit 119 to the piezoelectric element 18, A drive circuit (not shown) having a level shifter 133, a switch 134, and the like serves as drive means for applying a predetermined drive signal to the piezoelectric element 18.

  The shift register 131, the latch 132, the level shifter 133, the switch 134, and the piezoelectric element 18 are provided for each nozzle opening 13 of the ink jet recording head 10. The shift register 131, the latch 132, The level shifter 133 and the switch 134 generate drive pulses from the ejection drive signal and the relaxation drive signal generated by the drive signal generation circuit 119. Here, the drive pulse is an applied pulse that is actually applied to the piezoelectric element 18.

  In such an ink jet recording head 10, first, recording data (SI) constituting dot pattern data is serially transmitted from the output buffer 123 to the shift register 131 in synchronization with the clock signal (CK) from the oscillation circuit 117. Are set sequentially. In this case, first, the most significant bit data in the print data of all the nozzle openings 21 is serially transmitted. When the most significant bit data serial transmission is completed, the second most significant bit data is serially transmitted. . Similarly, the lower bit data is serially transmitted sequentially.

  When all the nozzles of the recording data of the bit are set in each shift register 131, the control unit 116 causes the latch 132 to output a latch signal (LAT) at a predetermined timing. In response to this latch signal, the latch 132 latches the print data set in the shift register 131. The recording data (LATout) latched by the latch 132 is applied to the level shifter 133 which is a voltage amplifier. When the recording data is “1”, for example, the level shifter 133 boosts the recording data to a voltage value that can drive the switch 134, for example, several tens of volts. The boosted recording data is applied to each switch 134, and each switch 134 is connected by the recording data.

  A drive signal (COM) generated by the drive signal generation circuit 119 is also applied to each switch 134. When the switch 134 is selectively connected, the piezoelectric element 18 connected to the switch 134 is selected. A driving signal is applied. As described above, in the illustrated ink jet recording head 10, it is possible to control whether or not the ejection driving signal is applied to the piezoelectric element 18 according to the recording data. For example, since the switch 134 is connected by the latch signal (LAT) during the period in which the recording data is “1”, the drive signal (COMout) can be supplied to the piezoelectric element 18, and the supplied drive signal ( The piezoelectric element 18 is displaced (deformed) by COMout). Further, since the switch 134 is in a disconnected state during a period in which the recording data is “0”, the supply of the drive signal to the piezoelectric element 18 is cut off. In the period in which the recording data is “0”, each piezoelectric element 18 holds the previous potential, so that the previous displacement state is maintained.

  The piezoelectric element 18 is a longitudinal vibration type piezoelectric element 18 as described above. When this longitudinal vibration type piezoelectric element 18 is used, the piezoelectric element 18 contracts in the longitudinal direction by charging to expand the pressure generating chamber 12, and the piezoelectric element 18 extends in the longitudinal direction by discharging to contract the pressure generating chamber 12. . In such an ink jet recording head 10, the volume of the corresponding pressure generation chamber 12 changes with charging / discharging of the piezoelectric element 18, so that droplets are ejected from the nozzle opening 13 using the pressure fluctuation of the pressure generation chamber 12. Can be discharged.

  Here, a drive waveform representing the drive signal (COM) of this embodiment input to the piezoelectric element 18 will be described. 4 is a drive waveform showing the drive signal of this embodiment, and FIGS. 5 and 6 are cross-sectional views showing the state of the meniscus of the nozzle opening.

  The drive waveform input to the piezoelectric element 18 is applied to the individual electrodes with the common electrode as a reference potential (0 V in this embodiment). The waveform shown in FIG. 4 has a basic shape, a discharge expansion element P01 that increases from the state in which the intermediate potential Vm is maintained to the first potential V1, a discharge hold element P02 that maintains the first potential V1 for a certain time, The discharge contraction elements P03 to P05 for lowering from the first potential V1 to the third potential V3, the damping hold element P06 for maintaining the third potential V3 for a certain time, and the control for increasing the potential from the third potential V3 to the intermediate potential Vm. It is comprised with the vibration expansion element P07.

  The discharge contraction elements P03 to P05 include an initial contraction element P03 that drops from the first potential V1 to the second potential V2, a hold element P04 that maintains the second potential V2 for a relatively short time, and a second potential V2. And a late contraction element P05 that lowers to the third potential V3.

  When such a drive waveform is supplied to the piezoelectric element 18, as shown in FIG. 5A, the piezoelectric element 18 is deformed in a direction in which the volume of the pressure generating chamber 12 is expanded by the discharge expansion element P01. Then, the meniscus in the nozzle opening 13 is drawn into the pressure generation chamber 12 side, and ink is supplied to the pressure generation chamber 12 from the reservoir 17 side. The expanded state of the pressure generating chamber 12 is maintained by the discharge hold element P02. At this time, as shown in FIG. 5B, the center portion of the meniscus is inverted in the ejection direction and is raised in a columnar shape. Next, the initial contraction element P03 is supplied and the piezoelectric element 18 expands. Thereby, the pressure generation chamber 12 is rapidly contracted from the expansion volume to the contraction volume corresponding to the second potential V2, and the ink in the pressure generation chamber 12 is pressurized. Thereby, as shown in FIG.5 (c), the growth of the columnar part of a meniscus is promoted. Subsequently, the hold element P04 is supplied, and the pressure generating chamber 12 is maintained in the contracted state over the supply period of the hold element P04. Meanwhile, as shown in FIG. 6A, the meniscus is drawn to the pressure generating chamber 12 side by the inertial force. At this timing, the late contraction element P05 is supplied and the ink in the pressure generation chamber 12 is pressurized, and as shown in FIGS. 6B to 6C, the front end of the meniscus having a columnar shape. The portion is torn off and discharged as fine ink droplets (fine dots). Moreover, the remaining part moves rapidly to the pressure generation chamber 12 side by the reaction which the front-end | tip part was torn off. After that, the contraction state of the pressure generation chamber 12 is maintained for a certain time by the vibration suppression hold element P06, and then the pressure generation chamber 12 is expanded and returned to the steady volume by the supply of the vibration expansion element P07. The damping expansion element P07 is supplied at a timing when the meniscus drawn to the pressure generating chamber 12 side by the damping hold element P06 is reversed and moves to the discharge side, and therefore absorbs the moving force of the meniscus to the discharge side. Acts like As a result, the meniscus vibration is converged in a short time. That is, the hold element P04 that constitutes the ejection contraction element functions as a damping element that dampens the ink (meniscus) in the pressure generation chamber 12 before ejecting the ink.

  In the present embodiment, in such an ejection pulse, a plurality of ejection pulses in which the time of the hold element P04 constituting the ejection contraction element is changed according to the viscosity of the ink is prepared, and the viscosity of the ejected droplet is set. In response, a plurality of ejection pulses are arranged separately.

  Here, categorizing a plurality of ejection pulses means determining and supplying an ejection pulse to be used according to the viscosity of the ink to be used, or determining a plurality of ejection pulses according to the viscosity of the ink to be used. An appropriate discharge pulse is supplied from a plurality of discharge pulses determined in accordance with a change in viscosity depending on the environmental temperature.

  For example, when the ink used in the ink jet recording head 10 is determined as described above, the viscosity information or the range of ejection pulses to be used is stored in the viscosity information storage unit 118 in the inspection process before shipment. The control unit 116 obtains this and executes a predetermined ejection pulse. If the viscosity of the ink to be used is not known in advance, a viscosity measuring means for measuring the viscosity of the ink to be used can be installed, and this viscosity measuring means becomes a part of the viscosity information acquiring means. According to this viscosity information, the optimal discharge pulse can be determined by the control unit 116 according to the viscosity stored in the viscosity information storage unit 118, and a predetermined discharge pulse can be generated accordingly.

  On the other hand, the control to change the ejection pulse based on the viscosity information changed according to the environmental temperature is executed by measuring the actual ink viscosity by the temperature detection means or the viscosity detection means and changing the ejection pulse accordingly. Is done. When such a discharge pulse is dynamically changed, a plurality of discharge pulses are included in the COM and either one is selected and supplied depending on the viscosity, or a plurality of COMs are formed. Any one may be used depending on the viscosity, and the control method is not particularly limited.

  FIG. 7 shows an example of the ejection pulse. FIG. 7A shows a discharge pulse for relatively low viscosity, and FIG. 7B shows a discharge pulse for relatively high viscosity. Here, the relatively high viscosity and the relatively low viscosity represent the viscosity in the comparison between the two, and the relatively low viscosity is generally referred to as high viscosity. The viscosity may be 10 m · Pas or higher. For example, a relatively high viscosity may be an ink viscosity at room temperature, a relatively low viscosity may indicate an ink viscosity that has decreased in a high temperature state, and a relatively high viscosity, for example, a viscosity of 20 m. -It refers to a high viscosity of Pa or higher, and a relatively low viscosity may refer to, for example, a viscosity of about 10 m · Pa (generally referred to as high viscosity).

  As shown in FIG. 7 (a), the low-viscosity discharge pulse, like the discharge pulse shown in FIG. 4, is a discharge expansion element P01 that rises from the state in which the intermediate potential Vm is maintained to the first potential V1, and The discharge hold element P02 that maintains the first potential V1 for a certain period of time, the discharge contraction elements P03, P04A, and P05 that drop from the first potential V1 to the third potential V3, and the vibration suppression that maintains the third potential V3 for a certain period of time The hold element P06 and a vibration damping expansion element P07 that increases the potential from the third potential V3 to the intermediate potential Vm are configured. The discharge contraction element includes an initial contraction element P03, a hold element P04A, and a late contraction element P05.

  On the other hand, similarly to the discharge pulse for high viscosity, as shown in FIG. 7B, the discharge expansion element P01, the discharge hold element P02, the discharge contraction elements P03, P04B, P05, and the damping hold It consists of an element P06 and a damping / expansion element P07. The discharge contraction element is composed of an initial contraction element P03, a hold element P04B, and a late contraction element P05, similarly to the discharge pulse for low viscosity.

  Here, the difference between the two is the times t1 and t2 of the hold elements P04A and P04B provided in the discharge contraction element. The time t2 of the hold element P04B for the discharge pulse for high viscosity is set to be longer than the time t1 of the hold element P04A for the discharge pulse for low viscosity.

  Since the hold elements P04A and P04B of the discharge contraction elements function as vibration damping of the ink during the discharge operation (before ink droplet discharge), the time t1 of the hold elements P04A and P04B according to the viscosity of the ink. , T2 can be changed to optimally function the vibration damping action according to the ink viscosity. As a result, minute dots can be stably ejected regardless of the viscosity of the ink. That is, when the ink has a high viscosity, the flow path resistance increases, so that the damping action of the ink itself is likely to be effective. In addition, when the ink has a low viscosity, the flow path resistance is small, so that the vibration damping action of the ink itself is difficult to work. In an ejection pulse in which hold elements P04A and P04B that provide a vibration damping action are provided in the ejection contraction element in order to eject a minute dot, if the ink has a high viscosity, the ink returns (here, the meniscus return). ) Is delayed, so that the minute dots can be stably ejected by increasing the time t2 of the hold element P04B. Further, when the ink has a low viscosity, the return of the ink is accelerated, and therefore, the minute dots can be stably ejected by shortening the time t1 of the hold element P04A.

  FIG. 8 shows another example of the ejection pulse. As shown in FIG. 8A, the low-viscosity discharge pulse includes a discharge expansion element P11 that raises the intermediate potential Vm to the fourth potential V4, and a discharge hold element P12 that maintains the fourth potential V4 for a certain period of time. The discharge contraction elements P13 to P19 that lower the fourth potential V4 to the eighth potential V8, the vibration suppression hold element P20 that maintains the eighth potential V8 for a certain time, and the eighth potential V8 to the intermediate potential Vm. And a vibration damping expansion element P21.

  The discharge contraction element includes a first contraction element P13 that lowers from the fourth potential V4 to the fifth potential V5, a first hold element P14 that maintains the fifth potential V5 for a certain period of time, and a fifth potential V5. A first expansion element P15 that raises the sixth potential V6, a second hold element P16 that maintains the sixth potential V6 for a certain period of time, an initial contraction element P17 that lowers the sixth potential V6 to the seventh potential V7, It includes a hold element P18A that maintains the seventh potential V7 for a certain period of time and a late contraction element P19 that lowers the seventh potential V7 from the seventh potential V7 to the eighth potential.

  When such a drive waveform is supplied to the piezoelectric element 18, the pressure generating chamber 12 is expanded to the expansion volume corresponding to the fourth potential V4 by the discharge expansion element P11. As a result, the meniscus is drawn into the pressure generating chamber 12 and ink is supplied from the reservoir 17 to the pressure generating chamber 12. The expanded state of the pressure generating chamber 12 is maintained for a certain time by the discharge hold element P12. At this time, the center portion of the meniscus is inverted in the ejection direction, and is raised to a columnar shape. Thereafter, the pressure generating chamber 12 is contracted by the first contraction element P13. This encourages the growth of the meniscus columnar portion. Then, after being maintained for a short time by the first hold element P14, the meniscus is damped by supplying the first expansion element P15 and expanding the pressure generating chamber 12 at the timing when the meniscus protrudes to the discharge side. . Then, after being maintained for a short time by the second hold element P16, the pressure generation chamber 12 is contracted by the initial contraction element P17, so that a meniscus grows in a columnar shape, and the pressure of the pressure generation chamber 12 is increased by the hold element P18A. The ink in the pressure generation chamber 12 is damped by being stopped for a certain period of time, and then the ink droplets of minute dots are ejected by supplying the late contraction element P19. Incidentally, the ink droplets ejected by such a drive waveform are much smaller than the ink droplet dots by the drive waveform shown in FIG. Further, as the drive voltage of the first expansion element P15, that is, the potential difference from the fifth potential V5 to the sixth potential V6 increases, the size of the ink droplet decreases.

  On the other hand, as shown in FIG. 8 (b), the high-viscosity discharge pulse includes a discharge expansion element P11, a discharge hold element P12, discharge contraction elements P13 to P19, a vibration suppression hold element P20, and a damping hold element P20. And a vibration expansion element P21. The discharge contraction elements include a first contraction element P13, a first hold element P14, a first expansion element P15, a second hold element P16, an initial contraction element P17, and a hold element P18B. And a late contraction element P19.

  Here, the difference between the two is the times t3 and t4 of the hold elements P18A and P18B provided in the discharge contraction element. The time t4 of the hold element P18B of the high-viscosity discharge pulse is set to be longer than the time t3 of the hold element P18A of the low-viscosity discharge pulse.

  Since the hold elements P18A and P18B of the discharge contraction element function as a damping action during the discharge operation (before ink discharge), the times t3 and t4 of the hold elements P18A and P18B are changed according to the viscosity of the ink. As a result, the vibration damping action can be optimally functioned according to the ink viscosity. As a result, minute dots can be stably ejected regardless of the viscosity of the ink.

  In the example shown in FIG. 8, the times t3 and t4 of the hold elements P18A and 18B are changed. However, as described above, the first hold element P14 of the discharge contraction element is also controlled before the same ink discharge. Since it functions as a vibration action, the time of the first hold element P14 may be changed. That is, the first hold element P14 may be the hold element described in the claims.

Example 1
The ink jet recording head 10 described above was driven with the drive waveform (drive signal) shown in FIG. At this time, ink having a viscosity of 20 m · Pas at normal temperature was ejected.

  Further, the time t2 of the hold element P04B shown in FIG. 7B is set to 3 μs.

(Comparative Example 1)
The same ink jet recording head 10 as in Example 1 was driven with the time t2 of the hold element P04B of the drive waveform shown in FIG. That is, high-viscosity ink was driven using a drive waveform used for discharging low-viscosity ink, for example, a drive waveform shown in FIG. The time t2 of the hold element P04B was set to 2 μs, and ink having the same viscosity (20 m · Pas) as in Example 1 was ejected.

  Then, the state of the ejected ink droplets in Example 1 and Comparative Example 1 was photographed. The result is shown in FIG. 9A is an image obtained by photographing the state of the ink droplet of Comparative Example 1, and FIG. 9B is an image obtained by photographing the state of the ink droplet of Example 1.

  As shown in FIG. 9A, the ejected ink droplet of Comparative Example 1 is observed to bend left and right and vary in the ejection direction, but in the case of FIG. 9B, very stable ejection is observed. Observed.

  Further, in Comparative Example 1, even when the ink droplets were ejected at the ejection cycle (ejection pulse cycle) of 10 KHz, as shown in FIG. In Example 1, even when the ejection cycle was 20 KHz, stable ink droplet ejection could be performed as shown in FIG. 9B.

  As can be seen from these results, it can be seen that by using the drive signal of the present invention, high viscosity and low viscosity can be distinguished, and high frequency discharge can be stably realized even at high viscosity and low viscosity. It was.

(Other embodiments)
As mentioned above, although each embodiment of this invention was described, the basic composition of this invention is not limited to what was mentioned above. For example, in the above-described embodiment, it has been described that two types of discharge pulses for high viscosity and low viscosity are distinguished. However, according to the viscosity range using a plurality of types of discharge pulses in which the time of the hold element is changed. It can be made to hit. In addition, the basic ejection pulse has been described as an example, but it goes without saying that the above-described damping element may be used as another damping element. Further, for example, a fine vibration pulse that slightly vibrates the piezoelectric element 18 may be provided in the drive signal described above to such an extent that ink is not ejected. Note that a trapezoidal pulse having a trapezoidal waveform can be used as the fine vibration pulse.

  In the above-described embodiment, the longitudinal vibration type piezoelectric element 18 is used as the pressure generating means. However, the present invention is not particularly limited to this, and for example, a lower electrode, a piezoelectric layer, and an upper electrode are stacked. A flexural deformation type piezoelectric element may be used. Incidentally, when the longitudinal vibration type piezoelectric element 18 is used, the piezoelectric element 18 contracts in the longitudinal direction by charging and expands the pressure generating chamber 12, and the piezoelectric element 18 expands in the longitudinal direction by discharging and contracts the pressure generating chamber 12. Let On the other hand, when a bending deformation type piezoelectric element is used as the pressure generating means, the piezoelectric element is deformed to the pressure generating chamber 12 side by charging to contract the pressure generating chamber 12, and the piezoelectric element is pressurized by discharging. The pressure generation chamber 12 is expanded by being deformed to the opposite side to the generation chamber 12. A drive signal for driving such a piezoelectric element has a shape in which the potential polarity of the drive signal described above is inverted.

  Further, as the pressure generating means, a so-called electrostatic actuator that generates static electricity between the diaphragm and the electrode, deforms the diaphragm by electrostatic force, and discharges droplets from the nozzle openings 13 may be used. Good.

  In the ink jet recording apparatus I described above, the ink jet recording head 10 (head units 1A, 1B) is mounted on the carriage 3 and moves in the main scanning direction. However, the present invention is not particularly limited thereto. The present invention can also be applied to a so-called line recording apparatus in which the ink jet recording head 10 is fixed and printing is performed simply by moving the recording sheet S such as paper in the sub-scanning direction.

  Furthermore, the present invention is intended for a wide range of liquid jet heads in general, for example, for manufacturing recording heads such as various ink jet recording heads used in image recording apparatuses such as printers, and color filters such as liquid crystal displays. The present invention can also be applied to a coloring material ejecting head, an organic EL display, an electrode material ejecting head used for forming an electrode such as an FED (field emission display), a bioorganic matter ejecting head used for biochip production, and the like. Needless to say, a liquid ejecting apparatus including such a liquid ejecting head is not particularly limited.

1 is a schematic perspective view of a recording apparatus according to Embodiment 1 of the present invention. FIG. 3 is a cross-sectional view of the recording head according to the first embodiment of the invention. FIG. 3 is a block diagram illustrating a control configuration of the recording apparatus according to the first embodiment of the invention. It is a wave form diagram which shows the drive signal which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the state of the meniscus concerning Embodiment 1 of this invention. It is sectional drawing which shows the state of the meniscus concerning Embodiment 1 of this invention. It is a wave form diagram which shows the drive signal which concerns on Embodiment 1 of this invention. It is a wave form diagram which shows the drive signal which concerns on the other example of Embodiment 1 of this invention. It is the image which image | photographed the discharge state of the ink droplet.

Explanation of symbols

  I ink jet recording apparatus (liquid ejecting apparatus), 10 ink jet recording head (liquid ejecting head), 12 pressure generating chamber, 13 nozzle opening, 17 reservoir, 18 piezoelectric element (pressure generating means), 111 printer controller, 112 print engine 116 control unit, 118 viscosity information storage unit, 119 drive signal generation circuit, 131 shift register, 132 latch, 133 level shifter, 134 switch

Claims (8)

A liquid jet driving device for driving a liquid jet head comprising a pressure generating chamber communicating with a nozzle opening for discharging liquid and a pressure generating means for causing a pressure change in the pressure generating chamber,
A discharge expansion element that expands the pressure generation chamber, a discharge hold element that holds the expansion state of the pressure generation chamber, and a discharge that contracts the pressure generation chamber to discharge the liquid droplets from the nozzle opening Driving means for supplying a series of driving signals including discharge pulses including contraction elements in this order to the pressure generating means;
Viscosity information acquisition means for acquiring viscosity information of the liquid to be discharged;
The discharge contraction element of the discharge pulse includes an initial contraction element that contracts the pressure generation chamber, a hold element that maintains a contraction state by the initial contraction element, and a late contraction that further contracts the pressure generation chamber from the initial contraction element With elements,
When the driving means can supply a plurality of ejection pulses having different hold element times of the ejection pulse, and the viscosity of the liquid is relatively high based on the viscosity information acquired by the viscosity information acquisition means A drive signal including a discharge pulse including a discharge pulse having a relatively long time as the hold element is supplied, and a drive signal including a discharge pulse including a relatively short time as the hold element as the viscosity of the liquid is relatively low. A liquid jet driving device characterized in that   The liquid ejecting drive apparatus according to claim 1, wherein the hold element suppresses vibration in the pressure generating chamber before the liquid is discharged.   The discharge contraction element includes a first contraction element that contracts the pressure generation chamber, a first hold element that maintains a contraction state of the pressure generation chamber by the first contraction element, and the first contraction element A first expansion element that expands the pressure generation chamber contracted by the first expansion element, the initial contraction element that contracts the pressure generation chamber expanded by the first expansion element, the hold element, and the late contraction element The liquid jet driving device according to claim 1, further comprising:   The liquid ejection driving apparatus according to claim 1, wherein the viscosity information is based on a type of liquid to be ejected.   5. The liquid ejection driving apparatus according to claim 1, wherein the viscosity information is based on an environmental temperature or a temperature of a liquid to be ejected. A liquid jet driving device according to any one of claims 1 to 5,
A liquid ejecting head, comprising: a pressure generating chamber communicating with a nozzle opening for discharging liquid; and a pressure generating means for causing a pressure change in the pressure generating chamber. A liquid jet driving device according to any one of claims 1 to 5,
A liquid ejecting apparatus comprising: a pressure generating chamber that communicates with a nozzle opening that discharges a liquid; and a liquid ejecting head that includes pressure generating means for causing a pressure change in the pressure generating chamber.   The liquid ejecting apparatus according to claim 7, further comprising a supply unit configured to supply the liquid ejecting head with a liquid having a viscosity in a range of 6 m · Pas to 20 m · Pas at normal temperature.