JP5126444B2 - Liquid ejecting drive device, and liquid ejecting head and liquid ejecting device including the same - Google Patents

Description

  The present invention relates to a liquid ejecting drive device 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.

JP 7-148240 A JP 2006-297176 A

  However, in the above-described conventional technology, the drive waveform is adjusted according to the change in viscosity. However, the discharge characteristics cannot be maintained particularly when a high-viscosity liquid such as 10 mPa · s or more is discharged. In addition, there is a problem that 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.

  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 ejecting drive apparatus capable of stably ejecting liquid when ejecting liquid from low viscosity to high viscosity, and a liquid ejecting head and a liquid ejecting apparatus including the same. With the goal.

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 that discharges the liquid from a reference potential, 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 the nozzle opening. Therefore, a drive means for supplying a series of drive signals including discharge pulses including the discharge contraction elements for contracting the pressure generation chamber in this order to the pressure generation means, and a viscosity for obtaining viscosity information of the liquid to be discharged comprising an information acquisition means, said driving means is equal potential serving as the reference, and the ejection expansion element together with the drive voltage amplitude is the potential difference of the discharge contraction element is different It can be supplied a plurality of discharge pulses whose voltage change rate varies, depending on the viscosity information the viscosity information acquisition unit acquires, if the viscosity is relatively high, the voltage change the driving voltage width is relatively small rate supplies a drive signal containing a relatively large ejection pulse, if the viscosity is relatively low, a drive signal the driving voltage width is relatively large the voltage change rate comprises a relatively small ejection pulse In the liquid jet driving device, the liquid jet driving device is provided.
In this aspect, when the viscosity of the liquid is relatively high, and supplies a drive signal voltage change rate of the driving voltage width is relatively small ejection expansion element comprises a relatively large ejection pulse, relative viscosity when low, the voltage change rate of the driving voltage width is relatively large discharge expansion element is adapted to supply drive signals including a relatively small ejection pulse, discharges stably from a high viscosity to low viscosity Can do.

Further, the driving means can supply a plurality of ejection pulses having different expansion voltage widths which are potential differences of the ejection expansion elements, and the viscosity is relatively determined according to the viscosity information acquired by the viscosity information acquisition means. when high, it supplies a driving signal to the expansion voltage range includes a relatively large ejection pulse, if the viscosity is relatively low, supplies a driving signal to the expansion voltage range includes a relatively small ejection pulse Is preferred. According to this, if the viscosity is relatively high, and supplies a drive signal expansion voltage range includes a relatively large ejection pulse, if the viscosity is relatively low, the expansion voltage range is relatively small discharge By supplying a drive signal including a pulse, it is possible to discharge more stably from a high viscosity to a low viscosity.

In addition, the liquid ejection driving apparatus that drives a liquid ejection head including a pressure generation chamber that communicates with a nozzle opening that discharges a liquid and a pressure generation unit that causes a pressure change in the pressure generation chamber. From the potential, 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 the pressure generation chamber contracts to discharge the liquid from the nozzle opening. A drive unit that supplies a series of drive signals including a discharge pulse including the discharge contraction elements in this order to the pressure generation unit; and a viscosity information acquisition unit that acquires viscosity information of the liquid to be discharged. The driving means has a plurality of discharges having different reference potentials, different drive voltage widths as potential differences of the discharge contraction elements, and different voltage change rates of the discharge expansion elements. When the viscosity is relatively high according to the viscosity information acquired by the viscosity information acquisition means, the drive voltage width is relatively small and the voltage change rate is relatively When a drive signal including an ejection pulse having a large and relatively low reference potential is supplied and the viscosity is relatively low, the drive voltage width is relatively large and the voltage change rate is It is preferable to supply a drive signal including an ejection pulse that is relatively small and has a relatively high reference potential. According to this, stable discharge from high viscosity to low viscosity becomes possible.

Further, the driving means can supply a plurality of ejection pulses having different expansion voltage widths which are potential differences of the ejection expansion elements, and the viscosity is relatively determined according to the viscosity information acquired by the viscosity information acquisition means. When the viscosity is high, a drive signal including an ejection pulse having a relatively small expansion voltage width is supplied. When the viscosity is relatively low, a drive signal including an ejection pulse having a relatively large expansion voltage width is supplied. It is preferable. According to this, more stable discharge can be performed.

The viscosity information is preferably based on the type of liquid to be discharged. According to this, it can drive with a suitable drive signal based on the viscosity of the liquid to be discharged.

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 a suitable drive signal according to the change of the viscosity based on a temperature change.

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 a wave form diagram which shows the drive signal which concerns on the other example of 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 a wave form diagram which shows the drive signal which concerns on the other example of Embodiment 1 of this invention. It is a wave form diagram which shows the drive signal which concerns on the comparative example 1 of this invention. It is the image which image | photographed the discharge state of the ink droplet.

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 alternately in a vertical direction, and an inactive region that does not contribute to vibration is fixed to a fixed substrate 22, and fixed. The substrate 22 is fixed to the base 23.

  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.

  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 this embodiment, the viscosity information storage unit 118 functions as a viscosity information acquisition unit. Although details will be described later, in the viscosity information storage unit 118, waveform information of an ejection pulse, for example, a drive voltage, in relation to the viscosity range. Information relating to the width and the potential difference of the ejection expansion 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 the shift registers 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. FIG. 4 is a drive waveform showing the drive signal of this embodiment.

  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 drive waveform is the basic shape shown in FIG. 4, and the first expansion element P01, which is a discharge expansion element that raises the intermediate potential Vm from the state in which the intermediate potential Vm is maintained to the first potential Va, and the first potential Va for a certain period of time. The first hold element P02, which is the discharge hold element to be maintained, the first contraction element P03, which is the discharge contraction element that drops from the first potential Va to the second potential Vb, and the second potential Vb are maintained for a certain period of time. The second hold element P04 is a vibration hold element, and the second expansion element P05 is a vibration expansion element that raises the potential from the second potential Vb to the intermediate potential Vm.

  When such a drive waveform is supplied to the piezoelectric element 18, the first expansion element P 01 causes the piezoelectric element 18 to deform in the direction of expanding the volume of the pressure generating chamber 12, and the meniscus in the nozzle opening 13 is changed. While being drawn into the pressure generation chamber 12 side, 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 first hold element P02. Next, the first 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 Vb, and the ink in the pressure generation chamber 12 is pressurized. By this pressurization, the meniscus moves rapidly in the discharge direction. Subsequently, the second hold element P04 is supplied, and the pressure generating chamber 12 is maintained in a contracted state over the supply period of the second hold element P04. Meanwhile, the meniscus continues to move to the discharge side even after the supply of the first contraction element P03 due to the inertial force. As a result, the tip of the columnar meniscus is broken and ejected as ink droplets. 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 pressure generating chamber 12 returns to the normal volume by the supply of the second expansion element P05. The second expansion element P05 is supplied at a timing when the meniscus drawn to the pressure generating chamber 12 side is reversed and moves to the discharge side, and thus acts to absorb the moving force of the meniscus to the discharge side. As a result, the meniscus vibration is converged in a short time.

  In the present embodiment, in such an ejection pulse, the drive voltage width VHa that is the potential difference between the first potential Va and the second potential Vb and the potential difference between the first expansion element P01, that is, the intermediate potential Vm and the first potential Va. A plurality of ejection pulses in which the expansion voltage width VHb, which is a potential difference between the first expansion element P01 and the voltage change rate corresponding to the inclination of the first expansion element P01, is changed according to the viscosity, and the viscosity of the droplet to be ejected is prepared. The 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. In accordance with the viscosity information, the control unit 116 determines an optimal discharge pulse 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. 5 shows an example of the ejection pulse. FIG. 5A shows a discharge pulse for relatively high viscosity, and FIG. 5B shows a discharge pulse for relatively low 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 mPa · s or more. 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 mPa A high viscosity equal to or greater than s, and a relatively low viscosity, for example, sometimes refers to a viscosity of about 10 mPa · s (generally referred to as high viscosity).

  Similar to the discharge pulse shown in FIG. 4, the high-viscosity discharge pulse includes a first expansion element P1A, which is a discharge expansion element that increases from the state in which the intermediate potential Vm is maintained to the first potential Va1, and a first potential Va1. The first hold element P2A, which is a discharge hold element that maintains a predetermined time, the first contraction element P3A, which is a discharge contraction element that drops from the first potential Va1 to the second potential Vb1, and the second potential Vb1 for a predetermined time. The second hold element P4A, which is a vibration suppression hold element to be maintained, and the second expansion element P5A, which is a vibration suppression expansion element that raises the potential from the second potential Vb1 to the intermediate potential Vm. The drive voltage width is VHa1, and the expansion voltage width is VHb1.

  On the other hand, the low-viscosity discharge pulse similarly includes a first expansion element P1B that is a discharge expansion element that raises the intermediate potential Vm from the state in which the intermediate potential Vm is maintained to a first potential Va2 that is higher than the first potential Va1, and a first potential Va2. The first hold element P2B, which is a discharge hold element that maintains a predetermined time, the first contraction element P3B, which is a discharge contraction element that drops from the first potential Va2 to the second potential Vb1, and the second potential Vb1 The second hold element P4B, which is a vibration suppression hold element to be maintained, and the second expansion element P5B, which is a vibration suppression expansion element that raises the potential from the second potential Vb1 to the intermediate potential Vm.

  Here, the difference between the two is that in the discharge pulse for low viscosity, the first expansion element P1B increases the potential to Va2 higher than the first potential Va1 having high viscosity, thereby increasing the driving voltage width for high viscosity. The drive voltage width VHa2 and the expansion voltage width VHb2 are larger than VHa1 and the expansion voltage width VHb1, and the inclination of the expansion element P1B is made smaller than the high viscosity so that the pressure generating chamber 12 is expanded more slowly than the case of the high viscosity. .

  In this case, if the head is designed so that proper discharge can be realized with a discharge pulse for high viscosity, the flow resistance becomes small at low viscosity, and the flow resistance becomes low when high frequency discharge is performed. Although the vibration damping operation is less effective, such a problem is prevented by applying a high voltage more slowly than the high viscosity as shown in the waveform of FIG.

  FIG. 6 shows another example of the discharge pulse for low viscosity, and the discharge pulse for high viscosity is shown for comparison.

  The low-viscosity ejection pulse further increases the intermediate potential from that shown in FIG. 5B and increases the intermediate potential from the intermediate potential Vm1 to the first potential Va2 higher than the first potential Va1. P1C, a first hold element P2C that is a discharge hold element that maintains the first potential Va2 for a certain period of time, a first contraction element P3C that is a discharge contraction element that lowers the first potential Va2 to the second potential Vb1, The second hold element P4C is a vibration suppression hold element that maintains the second potential Vb1 for a certain period of time, and the second expansion element P5C is a vibration suppression expansion element that raises the potential from the second potential Vb1 to the intermediate potential Vm. ing.

  In this case, compared with FIG. 5B, the slope of the first expansion element P1C and the drive voltage width VHa2 are the same as those in FIG. 5, but the expansion voltage width VHb2 is smaller than VHb1 in FIG. It has become. According to this, the expansion voltage width is reduced so that the time of the first expansion element P1C is shorter than that of the first expansion element P1B, and the time of the entire drive waveform is shortened to be more suitable for high frequency driving.

  FIG. 7 shows another example of the discharge pulse for low viscosity, and the discharge pulse for high viscosity is shown for comparison.

  The low-viscosity discharge pulse further increases the intermediate potential from the case of FIG. 6 and the first expansion element P1D, which is a discharge expansion element that raises the intermediate potential Vm2 to the first potential Va2 higher than the first potential Va1. A first hold element P2D that is a discharge hold element that maintains the first potential Va2 for a certain period of time, a first contraction element P3D that is a discharge contraction element that drops from the first potential Va2 to the second potential Vb2, and a second A second hold element P4D that is a vibration suppression hold element that maintains the potential Vb2 for a certain period of time, and a second expansion element P5D that is a vibration suppression expansion element that raises the potential from the second potential Vb2 to the intermediate potential Vm2. .

  In this case, as compared with FIG. 6, by lowering the second potential Vb2, the drive voltage width VHa2 becomes a larger drive voltage width VHa3, and the expansion voltage width becomes an expansion voltage width VHb3 smaller than VHb2. According to this, the expansion voltage width is reduced, the time of the first expansion element P1C is made shorter than that of the first expansion element P1B, the time of the entire drive waveform is shortened, and the drive voltage width is more suitable. To improve the discharge stability.

  6 and 7 exemplify the drive waveform in which the intermediate potential is raised as the low-viscosity discharge pulse to reduce the expansion voltage width, the control of the present invention expands the pressure generation chamber 12, and then The first expansion element is indispensable because it can be applied in the case of a discharge method for contraction. In addition, the expansion element has an expansion voltage width that is a potential difference between the discharge expansion elements of 30% or more, preferably 50% or more of the drive voltage width, and when the expansion voltage width is smaller than this, This is similar to the one without substantial expansion element.

Example 1
The ink jet recording head 10 described above was driven with the driving waveforms (driving signals) shown in FIGS. 5 (a) and 5 (b). The waveform in FIG. 5A is used when ink having a viscosity of 20 mPa · s is ejected at room temperature, and the waveform in FIG. 5B is ejected of ink having a viscosity of 10 mPa · s at high temperature. Used in case.

(Comparative Example 1)
The same ink jet recording head 10 as that of Example 1 was driven with the driving waveform shown in FIG. 8, and ink having a viscosity of 10 mPa · s was discharged at a high temperature.

  In addition, the drive waveform of the comparative example 1 shown in FIG. 8 has a drive voltage width and an expansion voltage width smaller than the discharge pulse for high viscosity shown in FIG. That is, the first expansion element P1a, the first hold element P2a, and the first contraction element P3a are provided, and the second hold element P4a and the second expansion element P5a are provided. This is in line with the control of increasing the voltage and decreasing the drive voltage as the viscosity decreases.

  Then, the case of the low viscosity (at high temperature) of Example 1 and the state of the ejected ink droplets of Comparative Example 1 were 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.

  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, two types of discharge pulses for high viscosity and low viscosity have been described as being divided, but a plurality of types of discharge in which the expansion voltage width and the voltage change rate of the discharge expansion element are changed are described. Depending on the viscosity range, a pulse can be used. 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.

  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), 40, 140 ink droplet, 41 , 141 tail, 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 (6)

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 for expanding the pressure generation chamber from a reference potential, a discharge hold element for maintaining the expanded state of the pressure generation chamber, and the pressure generation chamber for discharging the liquid from the nozzle opening Drive means for supplying a series of drive signals including discharge pulses including the discharge contraction elements for contracting in this order to the pressure generating means;
Viscosity information acquisition means for acquiring viscosity information of the liquid to be discharged;
The drive means is capable of supplying a plurality of discharge pulses having the same reference potential , different drive voltage widths as potential differences of the discharge contraction elements, and different voltage change rates of the discharge expansion elements. , depending on the viscosity information the viscosity information acquisition unit acquires, if the viscosity is relatively high, supplies a driving signal to the voltage change rate driving voltage width is relatively small it includes a relatively large ejection pulse and, if the viscosity is relatively low, the liquid ejection driving unit and supplying the driving signal to the driving voltage width is relatively large the voltage change rate includes a relatively small ejection pulse. The drive means can supply a plurality of discharge pulses having different expansion voltage widths, which are potential differences of the discharge expansion elements, and the viscosity is relatively high according to the viscosity information acquired by the viscosity information acquisition means to, said inflation voltage range supplies a drive signal containing a relatively small ejection pulse, if the viscosity is relatively low, to supply a driving signal to the expansion voltage range includes a relatively large ejection pulse The liquid jet driving apparatus according to claim 1, wherein 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 for expanding the pressure generation chamber from a reference potential, a discharge hold element for maintaining the expanded state of the pressure generation chamber, and the pressure generation chamber for discharging the liquid from the nozzle opening Drive means for supplying a series of drive signals including discharge pulses including the discharge contraction elements for contracting in this order to the pressure generating means;
Viscosity information acquisition means for acquiring viscosity information of the liquid to be discharged;
The drive means is capable of supplying a plurality of discharge pulses having different reference potentials , different drive voltage widths as potential differences of the discharge contraction elements, and different voltage change rates of the discharge expansion elements. , depending on the viscosity information the viscosity information acquisition unit acquires, if the viscosity is relatively high, the drive voltage range is relatively small, and the voltage change rate is relatively rather large, and the supplying a drive signal serving as a reference potential comprises a relatively low ejection pulse, if the viscosity is relatively low, the driving voltage width is relatively large, and the voltage change rate is relatively rather small And a drive signal including an ejection pulse having a relatively high potential as the reference is supplied. The drive means can supply a plurality of discharge pulses having different expansion voltage widths, which are potential differences of the discharge expansion elements, and the viscosity is relatively high according to the viscosity information acquired by the viscosity information acquisition means to, said inflation voltage range supplies a drive signal containing a relatively small ejection pulse, if the viscosity is relatively low, to supply a driving signal to the expansion voltage range includes a relatively large ejection pulse 4. The liquid jet driving apparatus according to claim 3, wherein The viscosity information, the liquid ejection driving apparatus according to any one of claims 1-4, characterized in that is based on the type of liquid to be ejected. The viscosity information, the liquid ejection driving apparatus according to any one of claims 1-4, characterized in that is based on the temperature of the liquid to be ambient temperature or discharge.