JP5663435B2 - Liquid ejecting apparatus and control method thereof - Google Patents

Description

  Embodiments described herein relate generally to a liquid ejection apparatus used in an ink jet printer or the like and a control method thereof.

  A so-called inkjet head, a liquid ejection device used in an inkjet printer or the like, includes a plurality of nozzles that eject ink, a plurality of pressure chambers that communicate with the nozzles, and pressure for ink introduction and ink ejection to these pressure chambers. A plurality of capacitive loads such as piezoelectric elements, a plurality of electrodes for applying a driving voltage to these piezoelectric elements, and nozzle plates (also referred to as orifice plates) each having nozzles for discharging ink at positions corresponding to the pressure chambers. Etc.) (for example, Patent Document 1). Each piezoelectric element and each electrode constitutes a capacitive actuator.

JP 2004-148604 A

  In the ink jet head, a distance between the nozzle and the medium, that is, a head gap is set so that the print medium on the ink receiving side does not contact the nozzle. A small head gap is set if the medium is only a thin sheet, and a larger head gap is set if a thick envelope is included.

  However, the ink ejected from the nozzle includes, in addition to the main ink droplet having a high ejection speed, an ink droplet so-called satellite having a small shape and a slow ejection speed. When a large head gap is set, the satellite is separated from the main ink droplet and landed on the print medium, and this landing deviation causes print unevenness, ghost, and the like, leading to deterioration of print quality. The landing deviation of the ink also depends on the conveyance speed of the printing medium, and the landing deviation increases as the conveyance speed increases. As a countermeasure, it is conceivable to reduce the conveyance speed of the printing medium, but there is a problem that the printing speed is naturally lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid ejection apparatus capable of obtaining good liquid ejection quality for a medium regardless of the distance between the nozzle and the medium that receives liquid ejection from the nozzle, and without lowering the conveyance speed of the medium. The control method is provided.

A liquid discharge apparatus according to an embodiment of the present invention includes a nozzle that discharges a liquid, a pressure chamber that communicates with the nozzle, and an actuator that operates by charging and discharging and applies deformation for liquid introduction and deformation for liquid discharge to the pressure chamber. And a voltage having a waveform including a first potential for applying deformation for introducing the liquid and a second potential for applying deformation for discharging the liquid within one cycle as a drive voltage for charging and discharging the actuator. The distance between the nozzle and the medium that receives liquid ejection from the nozzle is less than a predetermined value during the output drive circuit and the first potential period and the second potential period of the drive voltage output from the drive circuit. Control means for switching to the first pattern in the case of (2) and switching to the second pattern if the value is equal to or greater than a predetermined value. The second potential period T2 has the conditions of “T = T1 + T2”, “T1 = T / 3” and “T2 = 2 · T1”, and the second pattern has the first potential period T1 in the period T. In addition, regarding the period T2 of the second potential, the first pattern has the conditions of “T = T1 + T2”, “T1 = T1 of the first pattern” and “T2 = (3.6 to 4.2) · T1”. The driving voltage is set to be larger than the limit voltage at which no satellite is generated, and the driving voltage of the second pattern is set to a voltage at which no satellite is generated .

1 is a diagram illustrating an overall configuration of an inkjet head according to an embodiment. The figure which shows the structure of the principal part of FIG. The figure which expands and shows each pressure chamber and its peripheral part of FIG. The figure which shows the state which one pressure chamber of FIG. 3 expanded. The figure which shows the state which the pressure chamber which expanded like FIG. 4 contracted. The figure which shows the structure of the drive circuit of one Embodiment. The figure which shows operation | movement of step ST1 of the drive circuit of one Embodiment. The figure which shows operation | movement of step ST2 of the drive circuit of one Embodiment. The figure which shows operation | movement of step ST3 of the drive circuit of one Embodiment. The figure which shows the voltage waveform of each part in the drive circuit of one Embodiment. The figure which shows the waveform of the drive voltage applied at the time of the printing mode A of one Embodiment. The figure which shows the waveform of the drive voltage applied at the time of the printing mode B of one Embodiment. The figure which shows the maximum limit value (satellite free voltage) of the drive voltage with which the absence of a satellite at the time of applying the drive voltage of one Embodiment is maintained. The figure which shows the ink discharge speed (satellite free speed) corresponding to the maximum limit value of FIG. The figure which shows the maximum limit value (discharge stable limit voltage) of the drive voltage at which the discharge stability at the time of applying the drive voltage of one Embodiment is maintained. The figure which plots the data of FIG. 13 thru | or FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the overall configuration of an inkjet head that is a liquid ejection apparatus, and FIG. 2 shows a state in which the nozzle plate of the inkjet head is removed.

  A plate-like piezoelectric member 2 is embedded in a region along one side edge of the upper surface of the base 1 formed of the piezoelectric member. The end surface of the piezoelectric member 2 is flush with the side surface of the base 1. A plate-like piezoelectric member 2 is also embedded in a region along one side edge of the lower surface of the base 1. The end surface of the piezoelectric member 2 is flush with the side surface of the base 1.

  A nozzle plate (also referred to as an orifice plate) 3 formed of an insulating member is disposed on the end surface of the piezoelectric member 2 and the side surface of the base 1. The nozzle plate 3 has a plurality of nozzles 4 for ink ejection (for liquid ejection) arranged along the piezoelectric member 2 on the upper surface side of the base 1, and along the piezoelectric member 2 on the lower surface side of the base 1. A plurality of nozzles 4 for discharging ink are also arranged.

  A plurality of notches 11 are formed in a portion where the end surface of the piezoelectric member 2 on the upper surface side of the base 1 and the side surface of the base 1 overlap, in positions corresponding to the nozzles 4 and in communication with the nozzles 4. Is formed. A groove-shaped pressure chamber 12 is formed from these notches 11 to the upper surface of the piezoelectric member 2. Due to the piezoelectric member 2 and the base 1 existing between these pressure chambers 12, a pair of piezoelectric elements (capacitive load) that overlap in a state in which the polarization directions oppose each other and in a direction orthogonal to the direction in which the pressure chambers 12 are arranged. ) Is formed. The pair of piezoelectric elements constitute a capacitive actuator 13 that applies pressure for ink introduction (for liquid introduction) and ink ejection (for liquid ejection) to each pressure chamber 12. These capacitive actuators 13 serve as walls separating the pressure chambers 12.

As shown in FIG. 3, in order to apply a driving voltage to each capacitive actuator 13 on the inner peripheral surface of each pressure chamber 12, that is, on the side surface portion of each capacitive actuator 13 and the bottom portion of each pressure chamber 12. The electrode 14 is mounted. In order to prevent the electrodes 14 and the ink (liquid) in each pressure chamber 12 from coming into contact, the surface of each electrode 14 is covered with an insulating film 15.
Similarly, a plurality of pressure chambers 12, a plurality of capacitive actuators 13, a plurality of electrodes 14, and an insulating film 15 are provided on the lower edge side of the base 1.

  Each pressure chamber 12 of the piezoelectric member 2 on the upper surface side of the base 1 is closed with a cover 5. An ink inlet 6 is provided on the cover 5, and ink (liquid) flowing into the ink inlet 6 is guided to the pressure chambers 12. A plurality of conductive members 7 are led out from the electrodes 14 in each pressure chamber 12, and these conductive members 7 are connected to the circuit board 8. A drive circuit 9 that outputs a drive voltage to each capacitive actuator 13 is mounted on the circuit board 8.

  A protective mask plate 10 is mounted on the peripheral edge of the nozzle plate 3. The mask plate 10 is made of metal and has an opening 10a on the inside. In FIG. 1, the mask plate 10 is separated from the nozzle plate 3, but actually, the mask plate 10 is mounted in a state of surface contact with the nozzle plate 3. One end of a lead wire (ground wire) 21 is connected to the mask plate 10, and the other end of the lead wire 21 is connected to a ground line (conductive pattern) 8 a on the circuit board 8.

  Each of the capacitive actuators 13 has a capacitance C01, C12,. Hereinafter, for easy understanding, the capacitive actuator 13 having the capacitance C01 is referred to as an actuator C01, and the capacitive actuator 13 having the capacitance C12 is referred to as an actuator C12. These actuators C01, C12,... Are charged and discharged by the drive circuit 9, whereby the actuators C01, C12,... Repeat the deformation and return shown in FIGS.

  FIG. 3 shows a steady state in which the driving voltage is not applied to the actuators C01 and C12 and the pressure chamber 12 is not deformed. When the actuators C01 and C12 located on both sides of the pressure chamber 12 are charged in the opposite directions, the actuators C01 and C12 are deformed in directions away from each other as shown in FIG. Along with this deformation, the pressure chamber 12 is deformed in the expansion direction (deformation for liquid introduction), and ink is introduced into the pressure chamber 12. Thereafter, the actuators C01 and C12 are discharged and charged in the opposite direction, so that the actuators C01 and C12 are deformed in a direction approaching each other. Along with this, the pressure chamber 12 is reduced and deformed (deformation for liquid ejection), and ink in the pressure chamber 12 is ejected from the nozzle 4 due to an increase in pressure, and vibration of the ink in the pressure chamber 12 after the ejection Is suppressed (dumping). Then, when the actuators C01 and C12 are discharged, the actuators C01 and C12 return to the steady state of FIG.

A specific configuration of the drive circuit 9 is shown in FIG.
A DC power supply (first DC power supply) 31 that outputs DC voltage Vaa, for example, 10 V, and a DC power supply (second DC power supply) 32 that also outputs DC voltage Vaa are connected in series. The interconnection point of the DC power supplies 31 and 32 is grounded. The output voltage ± Vaa (= 2 · Vaa) of the series circuit of the DC power supplies 31 and 32 becomes a drive voltage for the actuator described later. This drive voltage ± Vaa has an amplitude (variable width) of a positive potential and a negative potential sandwiching the ground potential, and is arbitrarily selected within a range of about ± 7 V to ± 18 V so as to be compatible with various inks.

  The negative side of a DC power supply (third DC power supply) 33 that outputs a DC voltage Vcc is grounded. This DC voltage Vcc becomes a bias voltage for back gates of P-type MOS transistors P00, P01, P02,... Described later, and a drive voltage for drivers 42 and buffers 43, 44 described later. For example, a value higher than the DC voltage Vaa is selected as the value of the DC power supply Vcc. As described above, since the drive voltage ± Vaa is selected with a variable width of about ± 7 V to ± 18 V, for example, 24 V is selected as an appropriate value in consideration of avoiding latch-up due to overshoot of the electrode potential.

  Between the positive side (+ Vaa) of the DC power supply 31 and the ground (± 0), the first semiconductor element, for example, between the source and drain of the P-type MOS transistor P00 and the second semiconductor element, for example, the drain-source of the N-type MOS transistor N10 A series circuit is connected between the two. Between the interconnection point of the P-type MOS transistor P00 and the N-type MOS transistor N10 and the negative side (-Vaa) of the DC power supply 32, the drain and source of the third semiconductor element, for example, the N-type MOS transistor N20 are connected. The

  The back gate of the P-type MOS transistor P00 is connected to the positive side (+ Vcc) of the DC power supply 33. The back gates of the N-type MOS transistors N 10 and N 20 are connected to the negative side (−Vaa) of the DC power supply 32. An interconnection point between the P-type MOS transistor P00 and the N-type MOS transistor N10 is the output terminal Out0. This output terminal Out0 is connected to one end of the actuator C01.

  These P-type MOS transistor P00 and N-type MOS transistors N10 and N20 constitute a switch circuit that selectively forms a current-carrying path for charging / discharging with respect to one end of the actuator C01. When the P-type MOS transistor P00 is turned on and the N-type MOS transistors N10 and N20 are turned off, one end of the actuator C01 becomes the + Vaa potential. When the P-type MOS transistor P00 and the N-type MOS transistor N20 are turned off and the N-type MOS transistor N10 is turned on, one end of the actuator C01 becomes the ground potential (zero). When the P-type MOS transistor P00 and the N-type MOS transistor N10 are turned off and the N-type MOS transistor N20 is turned on, one end of the actuator C01 becomes −Vaa potential.

  Between the positive side (+ Vaa) of the DC power supply 31 and the ground (± 0), between the source and drain of the fourth semiconductor element such as the P-type MOS transistor P01 and between the source and drain of the fifth semiconductor element such as the N-type MOS transistor N11 A series circuit is connected between the two. Between the interconnection point of the P-type MOS transistor P01 and the N-type MOS transistor N11 and the negative side (−Vaa) of the DC power supply 32, the drain and source of the sixth semiconductor element, for example, the N-type MOS transistor N21 are connected. The

  The back gate of the P-type MOS transistor P01 is connected to the positive side (+ Vcc) of the DC power supply 33. The back gates of the N-type MOS transistors N11 and N21 are connected to the negative side (−Vaa) of the DC power supply 32. An interconnection point between the P-type MOS transistor P01 and the N-type MOS transistor N11 is the output terminal Out1. This output terminal Out1 is connected to the other end of the actuator C01.

  These P-type MOS transistor P01 and N-type MOS transistors N11 and N21 constitute a switch circuit that selectively forms a current-carrying path for charging and discharging with respect to the other end of the actuator C01. When the P-type MOS transistor P01 is turned on and the N-type MOS transistors N11 and N21 are turned off, the other end of the actuator C01 becomes + Vaa potential. When the P-type MOS transistor P01 and the N-type MOS transistor N21 are turned off and the N-type MOS transistor N11 is turned on, the other end of the actuator C01 becomes the ground potential. When the P-type MOS transistor P01 and the N-type MOS transistor N11 are turned off and the N-type MOS transistor N21 is turned on, the other end of the actuator C01 becomes −Vaa potential.

  The P-type MOS transistor P01 also functions as a first semiconductor element for the adjacent actuator C12. The N-type MOS transistors N11 and N21 also function as a second semiconductor element and a third semiconductor element for the adjacent actuator C12. That is, the switch circuit constituted by the P-type MOS transistor P01 and the N-type MOS transistors N11 and N21 also functions as a switch circuit that selectively forms a charging / discharging energization path for one end of the adjacent actuator C12.

  Between the positive side (+ Vaa) of the DC power supply 31 and the ground (± 0), between the source and drain of the fourth semiconductor element such as the P-type MOS transistor P02 and between the source and drain of the fifth semiconductor element such as the N-type MOS transistor N12 A series circuit is connected between the two. Between the interconnection point of the P-type MOS transistor P02 and the N-type MOS transistor N12 and the negative side (−Vaa) of the DC power supply 31, the drain and source of the sixth semiconductor element, for example, the N-type MOS transistor N22 are connected. The

  The back gate of the P-type MOS transistor P02 is connected to the positive side (+ Vcc) of the DC power supply 33. The back gates of the N-type MOS transistors N12 and N22 are connected to the negative side (−Vaa) of the DC power supply 32. An interconnection point between the P-type MOS transistor P02 and the N-type MOS transistor N12 is the output terminal Out2. This output terminal Out2 is connected to the other end of the actuator C12.

  The P-type MOS transistor P02 and the N-type MOS transistors N12 and N22 constitute a switch circuit that selectively forms a current-carrying path for charging / discharging with respect to the other end of the actuator C12.

The P-type MOS transistor P02 also functions as a first semiconductor element for the adjacent actuator C23. N-type MOS transistors N12 and N22 also function as a second semiconductor element and a third semiconductor element for adjacent actuator C23. That is, the switch circuit constituted by the P-type MOS transistor P02 and the N-type MOS transistors N12 and N22 also functions as a switch circuit that selectively forms a charging / discharging energization path for one end of the adjacent actuator C23.
Similar switch circuits are configured for the remaining actuators.

  On the other hand, reference numeral 40 denotes a main control unit which outputs common control signals WVA, WVB to the switch circuits and outputs individual control signals EN1, EN2, EN3,. These drive control signals are supplied to a plurality of logic control circuits 41 corresponding to each switch circuit. The main control unit 40 and each logic control circuit 41 operate with the DC voltage Vdd.

  Among the logic control circuits 41, the logic control circuit 41 corresponding to the switch circuit of the MOS transistors P00, N10, N20 turns the MOS transistors P00, N10, N20 on and off in response to the control signals WVA, WVB, EN1. Drive control signals DR1 [0], DR1 [1], DR1 [2] for driving are output. The logic control circuit 41 corresponding to the switch circuit of the MOS transistors P01, N11, N21 also outputs drive control signals DR2 [0], DR2 [1], DR2 [2] with the same configuration. The logic control circuit 41 corresponding to the switch circuit of the MOS transistors P02, N12, N22 also outputs the drive control signals DR3 [0], DR3 [1], DR3 [2] with the same configuration.

  The output drive control signal becomes a drive signal for the gate of each MOS transistor via the driver 42 and the buffers 43 and 44, respectively.

  The operation of the drive circuit 9 is shown in FIG. 6 and FIGS. Further, the voltage waveforms of the respective parts in the drive circuit 9 are shown in FIG. 10 as steps ST0 to ST3. Since the operation for all the actuators will be long, the driving of the actuators C01 and C12 will be mainly described.

  First, in step ST0, as shown in FIG. 6, the MOS transistors N10, N11, N12 are turned on, and a closed circuit (discharge path) for the actuators C01, C12 is formed through the ground. The output terminals Out0, Out1 and Out2 are at ground potential. At this time, the actuators C01 and C12 are in a steady state shown in FIG.

  In step ST1, as shown in FIG. 7, the MOS transistors P00, P02, N21 are turned on. As a result, the actuators C01 and C12 are charged with the voltage 2 · Vaa, respectively. By this charging, as shown in FIG. 4, the pressure chamber 12 is deformed in the expansion direction, and ink is introduced into the pressure chamber 12.

  In step ST2, as shown in FIG. 8, the MOS transistors P01, N20, N22 are turned on. As a result, the charging voltage of the actuators C01 and C12 is discharged through the DC power supplies 31 and 32, and the voltage 2 · Vaa is charged to the actuators C01 and C12 after the discharge. As a result of this discharge and charging, the pressure chamber 12 is deformed in the shrinking direction, as shown in FIG. The vibration of the ink inside is suppressed (damping).

  In step ST3, as shown in FIG. 9, the MOS transistors N10, N11, N12 are turned on as in step ST0. As a result, the actuators C01 and C12 are discharged, and the actuators C01 and C12 return to the steady state shown in FIG.

  As shown in FIG. 10, the drive voltage for charging / discharging the actuators C01 and C12 is a negative potential (first potential) for applying deformation for introducing ink to the pressure chamber 12, and for discharging ink to the pressure chamber 12 (and A positive potential (second potential) for applying deformation for vibration suppression has a waveform included in one cycle.

The main control unit 40 has a function of switching the negative potential period T1 and the positive potential period T2 of the drive voltage to a plurality of patterns in accordance with a mode setting signal input from the outside.
The mode setting signal is printed when the print medium on the side receiving the liquid discharge from the nozzle 4 is a thin sheet and the distance between the nozzle 4 and the print medium is set to a value less than a predetermined value, for example, less than 1 mm. Set mode A. The mode setting signal indicates that the printing mode B is used when the distance between the nozzle 4 and the printing medium is set to a value less than a predetermined value, for example, 1 mm or more, for both a thin paper and a thick envelope. Set.

  When the printing mode A is set, the main control unit 40 switches the negative potential period T1 and the positive potential period T3 of the drive voltage to the first pattern of the waveform shown in FIG. This first pattern has conditions of “T = T1 + T2” and “T1 <T2” with respect to the periods T1 and T2 in the cycle T. Note that T1 = T / 3 and T2 = 2 · (T / 3) are selected as the optimum values of the periods T1 and T2 that satisfy this condition.

  Further, when the print mode B is set, the main control unit 40 switches the negative potential period T1 and the positive potential period T2 of the drive voltage to the second pattern of the waveform shown in FIG. This second pattern has conditions of “T = T1 + T2” and “T1 << T2” with respect to the periods T1 and T2 in the cycle T. Note that “T1 = T1 of the first pattern” and “T2 = (3.6 to 4.2) · T1” are selected as the optimum values of the periods T1 and T2 that satisfy this condition.

  An experiment was conducted to apply a drive voltage that is fixed in the period T1 and slightly different in the period T2 to the actuators C01 and C12, so that the maximum limit value of the drive voltage that can be maintained without satellite (hereinafter referred to as satellite-free voltage) is obtained. The result confirmed by the above is the data of FIG. As experimental items, a single-nozzle driving pattern for ejecting ink droplets from a single nozzle 4, a multiple-nozzle driving pattern for ejecting ink droplets simultaneously from a plurality of nozzles 4, and a continuous multi-nozzle for ejecting ink droplets sequentially from a plurality of nozzles A drive pattern is prepared, and a satellite free voltage is obtained for each drive pattern. Data relating to the driving voltage of the first pattern when the printing mode A is set is shown in the uppermost stage, and data relating to the driving voltage of the second pattern when the printing mode B is set is shown in the second and subsequent stages.

  That is, the satellite-free voltage when applying the drive voltage of the first pattern of T1 = 2.30 μs and T2 = 4.60 μs is 15.3 V in the single nozzle drive pattern, 15.8 V in the multiple nozzle simultaneous drive pattern, The nozzle continuous drive pattern is 15.9V. The lowest satellite free voltage is 15.3V. By suppressing the driving voltage of the first pattern to the satellite free voltage of 15.3 V or less, no satellite is generated in any driving pattern.

  The satellite-free voltage when applying the second pattern drive voltage of T1 = 2.30 μs and T2 = 5.00 μs is 15.5 V for the single nozzle drive pattern, 16.2 V for the multiple nozzle simultaneous drive pattern, and multiple nozzles continuous The driving pattern is 16.0V. The satellite free voltage when applying the drive voltage of the second pattern of T1 = 2.30 μs and T2 = 5.40 μs is 16.1 V in the single nozzle drive pattern, 16.5 V in the multi-nozzle simultaneous drive pattern, and multi-nozzle continuous The driving pattern is 16.4V. Description of the remaining data is omitted. Among these satellite free voltages, the lowest is 15.5V. By suppressing the driving voltage of the second pattern to the satellite free voltage of 15.5 V or less, no satellite is generated in any driving pattern.

  Regardless of the first pattern and the second pattern, the lowest satellite-free voltage is 15.5 V, and the ink discharge speed (hereinafter referred to as satellite-free speed) when the drive voltage is set to 15.5 V is the period T1, T2. The result of confirming how it changes according to the above is the data shown in FIG. That is, when the ink discharge speed (m / s) when applying the drive voltage of the first pattern and the ink discharge speed (m / s) when applying the drive voltage of the second pattern are compared, in which drive pattern However, the ink ejection speed (m / s) when the driving voltage of the second pattern is applied is higher.

  In addition, a driving voltage that is fixed in period T1 and slightly different in period T2 is applied to the actuators C01 and C12 to maintain the stability (ejection stability) of the ink droplets ejected from the nozzles 4 (hereinafter referred to as the driving voltage maximum limit value). FIG. 15 shows the result of confirming the discharge stability limit voltage) by experiments. As in FIG. 13, data relating to the driving voltage of the first pattern when the printing mode A is set is shown in the uppermost stage, and data relating to the driving voltage of the second pattern when the printing mode B is set is shown in the second and subsequent stages. It shows.

  The meniscus of the nozzle 4 becomes larger as the drive voltage is increased. If this movement becomes too large, stable ink ejection becomes difficult. The ejection stability limit voltage is an upper limit value that enables stable ink ejection without excessive movement of the meniscus of the nozzle 4.

  The discharge stability limit voltage when applying the drive voltage of the first pattern of T1 = 2.30 μs and T2 = 4.60 μs is 28.2 V in the single nozzle drive pattern, 26.2 V in the multiple nozzle simultaneous drive pattern, and multiple nozzles In the continuous drive pattern, it becomes 24.4V. The lowest discharge stability limit voltage is 24.4V. By suppressing the drive voltage of the first pattern to the discharge stability limit voltage of 24.4 V or less, the discharge of ink droplets is stabilized in any drive pattern.

  The discharge stability limit voltage when applying the drive voltage of the second pattern of T1 = 2.30 μs and T2 = 5.00 μs is 24.0 V for the single nozzle drive pattern, 23.8 V for the multiple nozzle simultaneous drive pattern, and multiple nozzles In the continuous drive pattern, it is 23.1V. The satellite-free voltage when applying the second pattern drive voltage of T1 = 2.30 μs and T2 = 5.40 μs is 24.2 V for the single nozzle drive pattern, 20.0 V for the multiple nozzle simultaneous drive pattern, and multiple nozzles continuous The driving pattern is 19.7V. Description of the remaining data is omitted. Among these discharge stability limit voltages, the lowest is 16.9V. With respect to the driving voltage of the second pattern, by suppressing the ejection stability limit voltage to 16.9 V or less, the ejection of ink droplets is stabilized in any driving pattern.

  Of the satellite-free voltage in FIG. 13, the satellite-free speed in FIG. 14, and the discharge stability limit voltage in FIG. 15, the data in the multi-nozzle continuous drive pattern is graphed with the ratio of periods T1 and T2 (= T2 / T1) as a parameter. FIG. 16 is plotted.

  Regarding the driving voltage (T2 / T1 = 2.0) of the first pattern applied in the printing mode A, the satellite free speed is low, but the discharge stability limit voltage is high. When the driving voltage of the first pattern is set to 17.0 V, which is higher than the satellite free voltage, for example, the satellite free speed is increased and the satellite is generated. However, since the distance between the nozzle 4 and the printing medium is small, the main droplet of ink Even if the satellite droplets are flying away, there is almost no deviation in the landing of the ink, and the print quality does not deteriorate. Since the margin with the discharge stability limit voltage can be sufficiently large, the discharge stability is also good.

  Regarding the driving voltage of the second pattern to be applied in the printing mode B, “T1 = T1 of the first pattern” and “T2 = (3.6 to 4.2) · T1” which are optimum values in the periods T1 and T2. Satellite is generated even if the distance between the nozzle 4 and the printing medium is large by setting the satellite free voltage 16.2V while satisfying the conditions (area surrounded by the two-dot chain lines in FIG. 16). In addition, the ink discharge speed can also be increased to about 7.5 m / s, and as a result, it is possible to prevent uneven printing, ghosting, and the like due to ink landing deviation, and to ensure good print quality (liquid discharge quality). Since the margin with the discharge stability limit voltage can be sufficiently large, the discharge stability is also good. In addition, since no satellite is generated, it is not necessary to take measures such as lowering the conveyance speed of the printing medium and reducing the landing deviation of the ink, thereby avoiding a decrease in the printing speed.

  In the above embodiment, MOS transistors are used as the plurality of semiconductor elements, but other elements may be used as long as they have similar functions as long as they have similar functions.

In addition, the said embodiment is shown as an example and is not intending limiting the range of invention. The novel embodiment can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the spirit of the invention. In the embodiment, the scope of the invention is included in the gist, and is included in the invention described in the claims and an equivalent scope thereof.
Hereinafter, the description of the scope of claims at the beginning of application will be added.
[1]
A nozzle for discharging liquid;
A pressure chamber communicating with the nozzle;
An actuator that operates by charging and discharging and applies deformation for liquid introduction and liquid discharge to the pressure chamber;
A voltage having a waveform including a first potential for applying the deformation for introducing the liquid and a second potential for applying the deformation for discharging the liquid within one cycle is output as a drive voltage for charging and discharging the actuator. A drive circuit;
Control means for switching the period of the first potential and the period of the second potential of the drive voltage output from the drive circuit to a plurality of patterns according to the distance between the nozzle and the medium that receives liquid ejection from the nozzle. When,
A liquid ejection apparatus comprising:
[2]
In the first potential period and the second potential period of the drive voltage output from the drive circuit, the control means has a distance between the nozzle and a medium that receives liquid ejection from the nozzle being less than a predetermined value. Switch to the first pattern in the case, switch to the second pattern if the predetermined value or more,
The liquid ejecting apparatus according to [1], wherein
[3]
The first pattern has a condition of “T = T1 + T2” and “T1 <T2” with respect to the period T1 of the first potential and the period T2 of the second potential in the period T;
The second pattern has a relationship of “T = T1 + T2” and “T1 << T2” with respect to the first potential period T1 and the second potential period T2 in the period T.
The liquid ejection apparatus according to [2], wherein
[4]
The first pattern has conditions of “T = T1 + T2”, “T1 = T / 3” and “T2 = 2 · T1” with respect to the period T1 of the first potential and the period T2 of the second potential in the period T. ,
The second pattern is “T = T1 + T2”, “T1 = T1 of the first pattern” and “T2 = (3.6 to 4.3.6) with respect to the first potential period T1 and the second potential period T2 in the period T. 2) with the condition of T1 "
The liquid ejection apparatus according to [2], wherein
[5]
The first potential is a negative potential, and the second potential is a positive potential.
The liquid discharge apparatus according to any one of [1] to [4], wherein
[6]
The pressure chambers are a plurality of pressure chambers arranged across the actuator,
The actuator is a pair of piezoelectric elements that overlap in a direction perpendicular to the direction in which the pressure chambers are arranged in a state in which polarization directions oppose each other, and separates the pressure chambers.
The liquid discharge apparatus according to any one of [1] to [4], wherein
[7]
A nozzle for discharging liquid;
A pressure chamber communicating with the nozzle;
An actuator that operates by charging and discharging and applies deformation for introducing liquid, deformation for discharging liquid, and deformation for suppressing liquid vibration to the pressure chamber;
A voltage having a waveform including a first potential for applying the deformation for introducing the liquid and a second potential for applying the deformation for discharging the liquid within one cycle is output as a drive voltage for charging and discharging the actuator. A drive circuit;
In a liquid ejection device comprising:
The period of the first potential and the period of the second potential of the drive voltage output from the drive circuit are switched to a plurality of patterns according to the distance between the nozzle and the medium that receives liquid ejection from the nozzle.
A control method for a liquid ejection apparatus.

  DESCRIPTION OF SYMBOLS 1 ... Base, 2 ... Piezoelectric member, 3 ... Nozzle plate, 4 ... Nozzle, 9 ... Drive circuit, 12 ... Pressure chamber, 13 ... Electrostatic actuator, 14 ... Electrode, 15 ... Insulating film, 31 ... DC power supply 32 ... DC power supply, 33 ... DC power supply, P00, P01, P02 ... P-type MOS transistor, N10, N11, N12 ... N-type MOS transistor, N20, N21, N22 ... N-type MOS transistor, 40 ... main control unit

Claims (4)

A nozzle for discharging liquid;
A pressure chamber communicating with the nozzle;
An actuator that operates by charging and discharging and applies deformation for liquid introduction and liquid discharge to the pressure chamber;
A voltage having a waveform including a first potential for applying the deformation for introducing the liquid and a second potential for applying the deformation for discharging the liquid within one cycle is output as a drive voltage for charging and discharging the actuator. A drive circuit;
The first potential period and the second potential period of the drive voltage output from the drive circuit are the first pattern when the distance between the nozzle and the medium that receives liquid ejection from the nozzle is less than a predetermined value. And a control means for switching to the second pattern when the predetermined value is exceeded,
The first pattern has conditions of “T = T1 + T2”, “T1 = T / 3” and “T2 = 2 · T1” with respect to the period T1 of the first potential and the period T2 of the second potential in the period T. ,
The second pattern is “T = T1 + T2”, “T1 = T1 of the first pattern” and “T2 = (3.6 to 4.3.6) with respect to the first potential period T1 and the second potential period T2 in the period T. 2) The condition of T1 "
The driving voltage of the first pattern is set larger than a limit voltage at which no satellite is generated,
The driving voltage of the second pattern was set to a voltage that does not generate satellites.
A liquid discharge apparatus characterized by that. The first potential is a negative potential, and the second potential is a positive potential.
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The pressure chambers are a plurality of pressure chambers arranged across the actuator,
The actuator is a pair of piezoelectric elements that overlap in a direction perpendicular to the direction in which the pressure chambers are arranged in a state in which polarization directions oppose each other, and separates the pressure chambers.
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. A nozzle for discharging liquid;
A pressure chamber communicating with the nozzle;
An actuator that operates by charging and discharging and applies deformation for introducing liquid, deformation for discharging liquid, and deformation for suppressing liquid vibration to the pressure chamber;
A voltage having a waveform including a first potential for applying the deformation for introducing the liquid and a second potential for applying the deformation for discharging the liquid within one cycle is output as a drive voltage for charging and discharging the actuator. A drive circuit;
In a liquid ejection device comprising:
The first potential period and the second potential period of the drive voltage output from the drive circuit are the first pattern when the distance between the nozzle and the medium that receives liquid ejection from the nozzle is less than a predetermined value. Switch to the second pattern when the value exceeds the specified value,
The first pattern has conditions of “T = T1 + T2”, “T1 = T / 3” and “T2 = 2 · T1” with respect to the period T1 of the first potential and the period T2 of the second potential in the period T. ,
The second pattern is “T = T1 + T2”, “T1 = T1 of the first pattern” and “T2 = (3.6 to 4.3.6) with respect to the first potential period T1 and the second potential period T2 in the period T. 2) The condition of T1 "
The driving voltage of the first pattern is set larger than a limit voltage at which no satellite is generated,
The driving voltage of the second pattern was set to a voltage that does not generate satellites.
A control method for a liquid ejection apparatus.

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