Liquid ejection device and driving method of liquid ejection device

Abstract

The present invention provides a liquid ejection device and a driving method of the liquid ejection device that can heat liquid and can be miniaturized without complicating the structure. The liquid ejection device comprises: an ejection unit having a nozzle for ejecting liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for applying pressure variation to the liquid in the pressure chamber; a driving waveform generating unit that generates a driving waveform including a non-ejection vibration pulse that applies pressure variation to the liquid in the pressure chamber in a manner that does not eject the liquid from the nozzle when supplied to the piezoelectric actuator; and a control unit that controls the supply of the non-ejection vibration pulse to the piezoelectric actuator according to the temperature of the liquid in the pressure chamber.

Description

Technical Field

[0001] The present invention relates to a liquid ejecting device for ejecting liquid and a driving method thereof, and in particular to an inkjet recording device for ejecting ink as liquid and a driving method of the liquid ejecting device. Background Art

[0002] A liquid ejecting device is a device that has an ejecting portion and ejects various liquids from the ejecting portion in the form of liquid droplets. Although there are image recording devices such as inkjet printers and inkjet plotters as such liquid ejecting devices, recently, the liquid ejecting device has been effectively used in various manufacturing devices by effectively utilizing the advantage of being able to accurately eject a very small amount of liquid onto a predetermined position.

[0003] When liquid is ejected from such an ejection portion, the ejection characteristics will change according to the viscosity of the liquid. Since the viscosity of the liquid is correlated with the temperature, the lower the temperature, the higher the viscosity, and the higher the temperature, the lower the viscosity. Therefore, in the case where the ejection portion designed in a manner suitable for the viscosity of a commonly used liquid is placed in a low temperature environment, or in the case of ejecting a liquid with a high viscosity, in order to obtain the desired ejection characteristics, it is necessary to heat the liquid. A structure in which a heater is provided in the ejection portion in order to heat the liquid has been disclosed (for example, refer to Patent Document 1).

[0004] However, there is a problem that the structure of the liquid ejection device becomes complicated if a heater for heating is provided. In addition, in the structure in which the heater for heating is provided, a space for configuring the heater is required, thereby there is a problem that miniaturization is difficult.

[0005] Such a problem exists not only in inkjet recording devices, but also in liquid ejecting devices that eject liquids other than ink.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2011-136460 Summary of the invention

[0007] In view of such actual conditions, the present invention aims to provide a liquid ejection device and a method for driving the liquid ejection device that can heat liquid without complicating the structure and can be miniaturized.

[0008] The present invention for solving the above-mentioned problems is a liquid ejection device, characterized in that it comprises: an ejection unit, which comprises a nozzle for ejecting liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for applying pressure changes to the liquid in the pressure chamber; a drive waveform generating unit, which generates a drive waveform including a non-ejection vibration pulse that, when supplied to the piezoelectric actuator, applies pressure changes to the liquid in the pressure chamber in a manner that does not eject the liquid from the nozzle; and a control unit, which controls the supply of the non-ejection vibration pulse to the piezoelectric actuator according to the temperature of the liquid in the pressure chamber.

[0009] In addition, another embodiment of the present invention is a liquid ejection device, which comprises: an ejection unit, which comprises a nozzle for ejecting liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for applying pressure changes to the liquid in the pressure chamber; a drive waveform generating unit, which generates a drive waveform including a first drive waveform and a second drive waveform, wherein the first drive waveform comprises a non-ejection vibration pulse that, when supplied to the piezoelectric actuator, applies pressure changes to the liquid in the pressure chamber in a manner that does not cause the liquid to be ejected from the nozzle, the second drive waveform comprises a non-printing non-ejection vibration pulse that, when supplied to the piezoelectric actuator, applies pressure changes to the liquid in the pressure chamber in a manner that does not cause the liquid to be ejected from the nozzle, and a second drive waveform that, when supplied to the piezoelectric actuator, generates a drive waveform including a first drive waveform and a second drive waveform The piezoelectric actuator comprises an ejection vibration pulse that applies pressure variation to the liquid in the pressure chamber in such a manner that the liquid is ejected from the nozzle; a selection unit that selects one of supplying and not supplying the drive waveform to the piezoelectric actuator; a temperature detection unit that detects the temperature of the liquid; a control unit that controls the selection unit in such a manner that the non-ejection vibration pulse and the ejection vibration pulse are supplied to the piezoelectric actuator according to the printing data during a printing operation of printing an image on a printing medium according to the printing data, and controls the selection unit in such a manner that the non-ejection vibration pulse is supplied to the piezoelectric actuator according to the detection result of the temperature detection unit during a standby period outside the printing operation.

[0010] In addition, another embodiment of the present invention is a driving method of a liquid ejection device, characterized in that the liquid ejection device comprises: an ejection unit, which comprises a nozzle for ejecting liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for applying pressure changes to the liquid in the pressure chamber; a driving waveform generating unit, which generates a driving waveform including a non-ejection vibration pulse that, when supplied to the piezoelectric actuator, applies pressure changes to the liquid in the pressure chamber in a manner that does not cause the liquid to be ejected from the nozzle. In the driving method of the liquid ejection device, the supply of the non-ejection vibration pulse to the piezoelectric actuator is controlled according to the temperature of the liquid in the pressure chamber.

[0011] Moreover, another aspect of the present invention is a method for driving a liquid ejecting device, characterized in that the liquid ejecting device comprises: an ejecting portion, which comprises a nozzle for ejecting liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for applying pressure changes to the liquid in the pressure chamber; a driving waveform generating portion, which generates a driving waveform including a first driving waveform and a second driving waveform, wherein the first driving waveform comprises a non-ejecting vibration pulse that, when supplied to the piezoelectric actuator, applies pressure changes to the liquid in the pressure chamber in a manner that does not cause the liquid to be ejected from the nozzle, and the second driving waveform comprises a non-ejecting vibration pulse that, when supplied to the piezoelectric actuator, applies pressure changes to the liquid in the pressure chamber in a manner that does not cause the liquid to be ejected from the nozzle, A non-ejection vibration pulse for applying pressure changes to the liquid in the pressure chamber, and an ejection vibration pulse for applying pressure changes to the liquid in the pressure chamber in a manner that causes the liquid to be ejected from the nozzle when supplied to the piezoelectric actuator; a temperature detection unit that detects the temperature of the liquid, in which, during a printing operation of printing an image on a printing medium according to printing data, one of the non-ejection vibration pulse for printing and the ejection vibration pulse is supplied to the piezoelectric actuator according to the printing data, and during a standby period outside the printing operation, the non-ejection vibration pulse is supplied to the piezoelectric actuator according to the detection result of the temperature detection unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A diagram schematically showing the general structure of a recording device.

[0013] Figure 2 It is a cross-sectional view of the ejection portion.

[0014] Figure 3 A block diagram showing the electrical structure of a recording device.

[0015] Figure 4 denoted as a driving waveform of the first driving signal.

[0016] Figure 5: represents the driving waveform of the second driving signal.

[0017] Figure 6 A diagram for explaining the printing area and non-printing area of ​​a recording device.

[0018] Figure 7 This is a timing chart for explaining a method for driving a recording device.

[0019] Figure 8 This is a flowchart for explaining a method for driving a recording device.

[0020] Fig. 9 This is a drive waveform showing the correction of the vibration pulse when no discharge occurs during printing.

[0021] Fig.10 It is a cross-sectional view of the main parts of the recording device.

[0022] Fig.11 It is a side view of the main parts of the recording device.

[0023] Fig.12 It is a side view of the main parts of the recording device. DETAILED DESCRIPTION

[0024] Hereinafter, the present invention will be described in detail based on the implementation mode. However, the following description represents one mode of the present invention and can be arbitrarily changed within the scope of the present invention. Things marked with the same symbols in the drawings represent the same parts, and the description is appropriately omitted. In addition, in each of the drawings, X, Y, and Z represent three spatial axes that are orthogonal to each other. In this specification, the directions along these axes are set as the X direction, the Y direction, and the Z direction. The direction pointed by the arrow mark in each of the drawings is set as the positive (+) direction, and the opposite direction of the arrow mark is set as the negative (-) direction for description. In addition, the Z direction represents the vertical direction, the +Z direction represents vertically downward, and the -Z direction represents vertically upward.

[0025] Implementation Method 1

[0026] Figure 1 1 is a diagram schematically showing an ink jet recording apparatus as an example of the liquid ejecting apparatus according to the first embodiment of the present invention.

[0027] like Figure 1 As shown in the figure, an inkjet recording device 1 as an example of a liquid ejecting device is a printing device that ejects ink as a kind of liquid in the form of ink droplets onto a printing medium S such as printing paper and prints an image or the like by arranging dots formed on the printing medium S. In addition, as the printing medium S, any material such as a resin film or cloth can be used in addition to printing paper.

[0028] In the following, among the three spatial axes X, Y, and Z, the moving direction of the ejection unit 2 described later (in other words, the main scanning direction) is set as the X-axis, the conveying direction of the printing medium S orthogonal to the main scanning direction is set as the Y-axis, the surface parallel to the nozzle surface of the ejection unit 2 where the nozzle 35 is formed is set as the XY plane, the direction intersecting the nozzle surface, that is, the XY plane (in the present embodiment, orthogonal) is set as the Z-axis, and the ink droplets are set to be ejected in the +Z direction along the Z-axis.

[0029] The inkjet recording apparatus 1 includes a discharge unit 2 for discharging ink as liquid, a liquid container 3 , a conveying mechanism 4 for conveying a printing medium S, a control unit 5 as a control unit, a moving mechanism 6 , and a support table 9 .

[0030] The liquid container 3 independently stores multiple types (for example, multiple colors) of ink ejected from the ejection unit 2. Examples of the liquid container 3 include a cartridge that can be attached to and detached from the inkjet recording device 1, a bag-shaped ink bag formed of a flexible film, and an ink tank that can replenish ink. Although not particularly shown in the figure, multiple types of inks of different colors or types are stored in the liquid container 3.

[0031] Although not particularly shown in the figure, the control unit 5 is configured to include a control device such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage device such as a semiconductor memory. The control unit 5 controls the various elements of the inkjet recording device 1, that is, the ejection unit 2, the conveying mechanism 4, the moving mechanism 6, etc., by executing the program stored in the storage device through the control device.

[0032] The conveying mechanism 4 is a component that is controlled by the control unit 5 and conveys the print medium S in the +Y direction, and has, for example, a conveying roller 4a. In addition, the conveying mechanism 4 that conveys the print medium S is not limited to the conveying roller 4a, and may also be a component that conveys the print medium S by a belt or a roller.

[0033] The support table 9 is a member that supports the back side of the printing medium S that makes the ink droplets ejected from the ejection unit 2 fall on the surface side. In addition, although in the present embodiment, the support table 9 that supports the back side of the printing medium S is provided, it is not particularly limited to this, and the back side of the printing medium S may also be supported by a conveyor belt such as an endless belt.

[0034] The moving mechanism 6 is controlled by the control unit 5 so that the ejection unit 2 moves back and forth in the +X direction and the -X direction along the X axis. The +X direction and the -X direction along the X axis in which the ejection unit 2 moves back and forth by the moving mechanism 6 are directions intersecting the +Y direction in which the print medium S is transported.

[0035] Specifically, the moving mechanism 6 of this embodiment includes a conveyor body 7 and a conveyor belt 8. The conveyor body 7 is a generally box-shaped structure, i.e., a carriage, that accommodates the ejection unit 2 and is fixed to the conveyor belt 8. The conveyor belt 8 is an endless belt that is stretched along the ±X direction. Under the control of the control unit 5, the conveyor belt 8 rotates, so that the ejection unit 2 and the conveyor body 7 reciprocate along the X-axis and along a guide rail not shown. In addition, although Figure 1 In the embodiment, a single ejection unit 2 is mounted on the transport body 7, but the present invention is not particularly limited thereto, and a plurality of ejection units 2 may be mounted on the transport body 7. In addition, the liquid container 3 may be mounted on the transport body 7 together with the ejection unit 2.

[0036] In the present embodiment, in the region on the +X direction side, a wiper 10 is arranged as a wiping member for wiping the surface of the ejection portion 2 on which the nozzle 35 is formed, i.e., the nozzle surface (described later) on which the ejection portion 2 is provided. The wiper 10 of the present embodiment is composed of, for example, a plate-shaped member having elasticity and flexibility, such as rubber or an elastomer. During the wiping process, the nozzle surface is wiped by the wiper 10 by relative movement of the wiper 10 with the tip portion of the wiper 10 in contact with the nozzle surface. In addition, the wiping member for wiping the nozzle surface is not limited to the wiper 10, and for example, a member of various well-known structures such as a porous material such as a sponge, a fabric, a woven fabric, a non-woven fabric, etc. can also be used.

[0037] In addition, a cap 11 is arranged on the +X direction side, which is the standby position, i.e., the initial position, of the conveying body 7 so as to be adjacent to the wiper 10. The cap 11 is formed in a tray shape that can abut against the nozzle surface of the ejection unit 2. The cap 11 is configured so that the space inside the cap 11 can function as a sealed empty portion, and the nozzle surface can be closely attached in the sealed empty portion in a state facing the nozzle 35 described later of the ejection unit 2. In addition, a pump is connected to the cap 11 via a waste liquid pipe (not shown), and the sealed empty portion of the cap 11 can be negatively pressurized by driving the pump.

[0038] The ejection unit 2 is maintained by the wiper 10 and the cap 11. That is, in the present embodiment, the wiper 10 and the cap 11 serve as a "maintenance unit" for performing a maintenance process of discharging the ink as the liquid in the ejection unit. After the ink in the ejection unit 2 is discharged to the outside by the cap 11, the wiper 10 wipes the nozzle surface.

[0039] Here, refer to Figure 2 , so as to further explain the ejection portion 2 of this embodiment. In addition, Figure 2 2 is a cross-sectional view for explaining an example of the ejection portion 2.

[0040] The ejection portion 2 in this embodiment is unitized by stacking a plurality of structural components including a nozzle plate 36, a connecting plate 39, a pressure chamber forming substrate 40, a vibration plate 45, a plastic substrate 41, a piezoelectric actuator 43, a protective substrate 51, a retaining frame 42, etc., and bonding them using adhesives or the like.

[0041] The pressure chamber forming substrate 40 in this embodiment has a plurality of pressure chambers 44 respectively connected to a plurality of nozzles 35 formed on the nozzle plate 36. A plurality of piezoelectric actuators 43 are provided in a manner corresponding to each pressure chamber 44. The piezoelectric actuator 43 is also called a piezoelectric element, and is a driving element that places a piezoelectric body between electrodes facing each other. The piezoelectric actuator 43 is deformed based on a driving signal, thereby vibrating the vibration plate 45, thereby changing the pressure of the ink in the pressure chamber 44. A vibration plate 45 is provided between the pressure chamber 44 and the piezoelectric actuator 43, and the opening on the -Z direction side of the pressure chamber 44 is sealed by the vibration plate 45, thereby dividing a part of the pressure chamber 44. In addition, the pressure chamber forming substrate 40 and the vibration plate 45 can also be formed integrally. Moreover, in the areas corresponding to the pressure chambers 44 on the vibration plate 45, the piezoelectric actuators 43 are stacked respectively. The piezoelectric actuator 43 of this embodiment is constituted by, for example, sequentially stacking a first electrode, a piezoelectric layer, and a second electrode (not shown) on a vibration plate 45. The piezoelectric actuator 43 thus constituted is flexed and deformed when an electric field corresponding to the potential difference between the two electrodes is applied between the first electrode and the second electrode. In addition, either one of the first electrode and the second electrode constitutes an independent electrode provided for each piezoelectric actuator 43, and the other one constitutes a common electrode common to a plurality of piezoelectric actuators 43.

[0042] In addition, a wiring substrate 53, which is a flexible substrate on which a driving circuit 52 for driving the piezoelectric actuator 43 is mounted, is connected to the piezoelectric actuator 43. Although not particularly illustrated in the present embodiment, lead wires connected to the electrodes of the piezoelectric actuator 43 are led out to the surface of the pressure chamber forming substrate 40, and the wiring substrate 53 is electrically connected to the lead wires. In addition, the driving circuit 52 may be installed inside the ejection portion 2, and the connection between the driving circuit 52 and the piezoelectric actuator 43 is not limited to the wiring substrate 53, and may be realized by bonding wires or film-formed wiring.

[0043] The protection substrate 51 is fixed to the surface on the −Z direction side of the pressure chamber forming substrate 40 , thereby protecting the plurality of piezoelectric actuators 43 .

[0044] A connecting plate 39 having an area wider than that of the pressure chamber forming substrate 40 is joined to the surface on the +Z direction side of the pressure chamber forming substrate 40 when viewed from above in the +Z direction. The connecting plate 39 of the present embodiment includes a nozzle connecting port 46 connecting the pressure chamber 44 and the nozzle 35, a common liquid chamber 47 provided in common in each pressure chamber 44, and an independent connecting port 48 connecting the common liquid chamber 47 and the pressure chamber 44. The common liquid chamber 47 is a space extending along the ±Y direction, which is the direction in which the nozzles 35 are arranged side by side. In the present embodiment, two common liquid chambers 47 are formed in a manner corresponding to the rows of two nozzles 35 provided on the nozzle plate 36. A plurality of independent connecting ports 48 are formed in a manner corresponding to each pressure chamber 44 along the ±Y direction, which is the nozzle row direction. The independent connecting port 48 is connected to the end of the pressure chamber 44 on the opposite side of the portion connected to the nozzle connecting port 46.

[0045] A nozzle plate 36 formed with a plurality of nozzles 35 is bonded to a substantially central portion of the surface on the +Z direction side of the connecting plate 39. The nozzle plate 36 in this embodiment is a plate having a smaller outer shape than the connecting plate 39 when viewed from above in the +Z direction. The nozzle plate 36 is bonded by an adhesive or the like in a region where the nozzle connecting ports 46 are opened at a position offset from the opening of the common liquid chamber 47 in the surface on the +Z direction side of the connecting plate 39, in a state where the nozzle connecting ports 46 and the plurality of nozzles 35 are connected to each other. A total of two nozzle rows are formed on the nozzle plate 36 in this embodiment, in which the plurality of nozzles 35 are arranged side by side along the Y axis. The surface on the +Z direction side of the nozzle plate 36 is a nozzle surface 37.

[0046] Furthermore, a plastic substrate 41 is bonded to the surface on the +Z direction side of the connecting plate 39 at a position offset from the nozzle plate 36. The plastic substrate 41 seals the opening of the common liquid chamber 47 on the surface on the +Z direction side of the connecting plate 39 while being positioned on and bonded to the surface on the +Z direction side of the connecting plate 39. The plastic substrate 41 has a function of relaxing pressure fluctuations in the ink flow path, especially in the common liquid chamber 47, by flexing and deforming.

[0047] The pressure chamber forming substrate 40, the protective substrate 51, and the connecting plate 39 are fixed to the holder 42. Inside the holder 42, an introduction liquid chamber 49 communicating with the common liquid chamber 47 of the connecting plate 39 is formed on both sides sandwiching the pressure chamber forming substrate 40. In addition, in the present embodiment, the introduction liquid chamber 49 of the holder 42 and the common liquid chamber 47 of the connecting plate 39 are combined, which is also called a manifold.

[0048] In addition, on the surface of the holder 42 on the -Z direction side, an inlet 50 communicating with each inlet liquid chamber 49 is opened. The inlet 50 is communicated with the liquid container 3 via a flow channel member having a valve mechanism (not shown), etc., and the ink sent from the liquid container 3 is introduced into the inlet 50, the inlet liquid chamber 49 and the common liquid chamber 47, and is supplied from the common liquid chamber 47 to each pressure chamber 44 through the independent communication port 48.

[0049] In such an ejection section 2, when the ink fills the flow path from the inlet liquid chamber 49 through the common liquid chamber 47 and the pressure chamber 44 to the nozzle 35, the piezoelectric actuator 43 is driven to generate a pressure change in the ink in the pressure chamber 44, and the ink is ejected from the predetermined nozzle 35 through the pressure change.

[0050] In addition, the inkjet recording device 1 includes a control unit 5. Figure 3 The electrical structure of this embodiment is described below. Figure 3 2 is a block diagram showing an electrical configuration of an ink jet recording apparatus 1 according to Embodiment 1 of the present invention.

[0051] like Figure 3 As shown, the ink jet recording apparatus 1 includes a printer controller 210 as a control unit and a printer engine 220 .

[0052] The printer controller 210 is an element that controls the entire inkjet recording apparatus 1, and in this embodiment, is provided in the control unit 5 provided in the inkjet recording apparatus 1. The printer controller 210 corresponds to the "control unit" described in the claims.

[0053] The printer controller 210 includes an external interface 211 (hereinafter referred to as external I / F 211), a RAM 212 for temporarily storing various data, a ROM 213 for storing control programs, etc., and a control processing unit 214 configured to include a CPU, etc. In addition, the printer controller 210 includes an oscillation circuit 215 for generating a clock signal, a drive signal generation unit 216 for generating a drive signal for supplying to the ejection unit 2, and an internal interface 218 (hereinafter referred to as internal I / F 218) for transmitting dot pattern data (also referred to as bitmap data) developed based on the drive signal or print data to the printer engine 220.

[0054] The external I / F 211 receives print data including character codes, graphic functions, image data, etc. from an external device such as a host computer, etc. In addition, the external I / F 211 outputs a busy signal (BUSY) or an acknowledgement signal (ACK) to the external device.

[0055] RAM 212 functions as a receiving buffer 212A, an intermediate buffer 212B, an output buffer 212C, and a working memory (not shown). The receiving buffer 212A temporarily stores the printing data received through the external I / F 211, the intermediate buffer 212B stores the intermediate code data converted by the control processing unit 214, and the output buffer 212C stores the dot pattern data. The dot pattern data is composed of printing data obtained by decoding (translating) the grayscale data.

[0056] Furthermore, in addition to a control program (control routine) for executing various data processes, font data, graphic functions, and the like are stored in the ROM 213 .

[0057] The control processing unit 214 reads the print data in the receiving buffer 212A, and stores the intermediate code data obtained by converting the print data in the intermediate buffer 212B. In addition, the intermediate code data read from the intermediate buffer 212B is analyzed, and the intermediate code data is expanded into dot pattern data with reference to the font data and graphic functions stored in the ROM 213. After performing the required modification processing, the control processing unit 214 stores the expanded dot pattern data in the output buffer 212C.

[0058] Furthermore, if one line of dot pattern data is obtained in the ejection unit 2, the one line of dot pattern data is output to the ejection unit 2 through the internal I / F 218. Furthermore, when one line of dot pattern data is output from the output buffer 212C, the expanded intermediate code data is deleted from the intermediate buffer 212B, and the next expansion process for the intermediate code data is performed.

[0059] The drive signal generating unit 216 generates a first drive signal COM1 and a second drive signal COM2. Here, the first drive signal COM1 and the second drive signal COM2 are signals represented by drive waveforms, also referred to as first drive waveforms COM1 and second drive waveforms COM2. In addition, the drive signal generating unit 216 is a component that generates a drive signal represented by a drive waveform, and is equivalent to a drive waveform generating unit that generates a drive waveform.

[0060] Although the details will be described later, the first driving signal COM1 is a signal including a non-discharge vibration pulse NP1 for driving the piezoelectric actuator so as not to discharge ink droplets from the nozzle 35 .

[0061] Although the details will be described later, the second drive signal COM2 includes an ejection vibration pulse DP for driving the piezoelectric actuator 43 in a manner to eject ink droplets from the nozzle 35 , and a non-ejection vibration pulse NP2 for driving the piezoelectric actuator 43 in a manner not to eject ink droplets from the nozzle 35 .

[0062] The first drive signal COM1 and the second drive signal COM2 generated by the drive signal generating unit 216 are selectively supplied to one electrode of the independent electrodes of the piezoelectric actuator 43 .

[0063] The printer engine 220 is configured to include a discharge unit 2 , a conveying mechanism 4 , a moving mechanism 6 , and a temperature detection unit 219 .

[0064] The ejection unit 2 includes a drive circuit 52 having a shift register circuit, a latch circuit, a decoder, a control logic, a level converter circuit, and a switch circuit, and the piezoelectric actuator 43 .

[0065] The shift register circuit is composed of a first shift register 122A and a second shift register 122B.

[0066] In addition, the latch circuit is composed of a first latch circuit 123A and a second latch circuit 123B.

[0067] Furthermore, the level shifter circuit is composed of a first level shifter 124A and a second level shifter 124B.

[0068] In addition, the switch circuit is composed of a first switch 125A and a second switch 125B.

[0069] Although not particularly shown in the figure, each shift register 122A, 122B, each latch circuit 123A, 123B, each level converter 124A, 124B, and each switch 125A, 125B are respectively constituted by a shift register element, a latch element, a level converter element, and a switch element provided for each nozzle 35 of the ejection unit 2. These shift registers 122A, 122B, latch circuits 123A, 123B, level converters 124A, 124B, switches 125A, 125B, and the piezoelectric actuator 43 are electrically connected in this order.

[0070] The ejection unit 2 drives the piezoelectric actuator 43 based on the recording data (SI) from the printer controller 210. In the present embodiment, since the recording data is sent to the ejection unit 2 in the order of the high-order group and the low-order group of the recording data, first, the high-order group of the recording data is placed in the second shift register 122B. For all the nozzles 35, when the high-order group of the recording data is placed in the second shift register 122B, these high-order groups will be transferred to the first shift register 122A. At the same time, the low-order group of the recording data is placed in the second shift register 122B.

[0071] The first latch circuit 123A is electrically connected to the rear stage of the first shift register 122A, and the second latch circuit 123B is electrically connected to the rear stage of the second shift register 122B. Moreover, when the latch signal (LAT) from the printer controller 210 is input to each latch circuit 123A and 123B, the first latch circuit 123A latches the high-order group of the recording data, and the second latch circuit 123B latches the low-order group of the recording data. The recording data (high-order group, low-order group) latched in each latch circuit 123A and 123B are output to the decoder 126 respectively. The decoder 126 generates pulse selection data for selecting the non-ejection vibration pulse NP1, the ejection vibration pulse DP, and the non-ejection vibration pulse NP2 in printing that constitute the first drive signal COM1 and the second drive signal COM2 based on the high-order group and the low-order group of the recording data.

[0072] The pulse selection data is generated for each of the first drive signal COM1 and the second drive signal COM2. That is, the first pulse selection data corresponding to the first drive signal COM1 is composed of one bit of data. In addition, the second pulse selection data corresponding to the second drive signal COM2 is composed of one bit of data.

[0073] In addition, the decoder 126 is also input with a timing signal from the control logic 127. The control logic 127 generates a timing signal in synchronization with the input of a latch signal or a channel signal. The timing signal is also generated for each of the first drive signal COM1 and the second drive signal COM2. Each pulse selection data generated by the decoder 126 is sequentially input to each level converter 124A, 124B from the high-order side at the timing specified by the timing signal. These level converters 124A, 124B function as voltage amplifiers, and when the pulse selection data is "1", they output a voltage value that can drive the corresponding switches 125A, 125B, for example, output an electrical signal boosted to several tens of volts. That is, when the first pulse selection data is "1", an electrical signal is output to the first switch 125A, and when the second pulse selection data is "1", an electrical signal is output to the second switch 125B and becomes a connected state.

[0074] The first drive signal COM1 from the drive signal generating unit 216 is supplied to the input side of the first switch 125A, and the second drive signal COM2 from the drive signal generating unit 216 is supplied to the input side of the second switch 125B. In addition, the piezoelectric actuator 43 is electrically connected to the output sides of the switches 125A and 125B. Moreover, the first switch 125A and the second switch 125B are provided for each type of drive signal generated, and are interposed between the drive signal generating unit 216 and the piezoelectric actuator 43, so that the first drive signal COM1 and the second drive signal COM2 are selectively supplied to the piezoelectric actuator 43. In addition, when both the first switch 125A and the second switch 125B are in the cut-off state, the first drive signal COM1 and the second drive signal COM2 are not supplied to the piezoelectric actuator 43.

[0075] Such pulse selection data controls the operation of each switch 125A, 125B. That is, during the period when the pulse selection data input to the first switch 125A is "1", the first switch 125A is connected to the on state, and the first drive signal COM1 is supplied to the piezoelectric actuator 43. Similarly, during the period when the pulse selection data input to the second switch 125B is "1", the second switch 125B is connected to the on state, and the second drive signal COM2 is supplied to the piezoelectric actuator 43. Moreover, the drive signal applied to the piezoelectric actuator 43 according to the supplied first drive signal COM1 and second drive signal COM2, that is, the so-called applied pulse, changes. On the other hand, during the period when the pulse selection data input to each switch 125A, 125B are all "0", each switch 125A, 125B is in the off state, and the first drive signal COM1 and the second drive signal COM2 are not supplied to the piezoelectric actuator 43. In short, pulses during the period when the pulse selection data is set to "1" are selectively supplied to the piezoelectric actuator 43. In the period when the pulse selection data is all "0", the piezoelectric actuator 43 maintains a slightly previous potential and thus maintains a slightly previous displacement state.

[0076] In this way, in this embodiment, the decoder 126, the control logic 127, the respective level converters 124A, 124B, and the respective switches 125A, 125B all function as a "selection unit" that supplies either the first drive signal COM1 or the second drive signal COM2 to the piezoelectric actuator 43 or does not supply both of them.

[0077] In addition, the printer controller 210 controls the piezoelectric actuator 43 to supply the non-ejection vibration pulse NP1 of the first drive signal COM1 and the non-ejection vibration pulse NP2 of the second drive signal COM2 to the piezoelectric actuator 43 based on the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219. Here, the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 may be the temperature of the ink in the pressure chamber directly detected, or may be the temperature inferred from the temperature of the ink in the pressure chamber 44. For example, a temperature detection unit 219 may be provided to detect the temperature of the ink in the pressure chamber 44 or the temperature of the ink in the flow channel connected to the pressure chamber, such as a manifold, and the detection result of the temperature detection unit 219 may be set as the temperature of the ink in the pressure chamber 44. In addition, the temperature detection unit 219 may adopt various well-known structures provided in contact with the ejection unit 2. That is, the temperature detection unit 219 may be provided on the wiring substrate 53, the protective substrate 51, the holder 42, the plastic substrate 41, etc., and the temperature of the ink in the pressure chamber 44 may be estimated based on the detection results. Furthermore, the temperature detection unit 219 may be provided in the inkjet recording device 1, and the temperature of the ink in the pressure chamber 44 may be estimated based on the detection results of the temperature detection unit 219 provided in the inkjet recording device 1. In addition, the temperature of the ink droplets ejected from the nozzle 35 may be detected by the temperature detection unit 219, and the detection results may be used as the temperature of the ink in the pressure chamber 44.

[0078] Such a temperature detection unit 219 is a component that detects temperature, and for example, a contact-type temperature sensor such as a thermoresistor, a thermocouple, or a thermistor can be used.

[0079] Next, the first drive signal COM1 and the second drive signal COM2 generated by the drive signal generating unit 216 and the supply control of the first drive signal COM1 and the second drive signal COM2 to the piezoelectric actuator 43 will be described. Figure 4 : represents the driving waveform of the first driving signal COM1. Figure 5 : represents the driving waveform of the second driving signal COM2.

[0080] like Figure 4As shown in FIG. 1 , the first drive signal COM1 is repeatedly generated by the drive signal generating unit 216 for each unit period T specified by the clock signal sent from the oscillation circuit 215. The unit period T is also called a discharge period T or a recording period T, and corresponds to one pixel of an image or the like printed on the printing medium S. In the present embodiment, the first drive signal COM1 is a signal having a non-discharge vibration pulse NP1 for driving the piezoelectric actuator 43 so as not to discharge ink droplets from the nozzle 35 within one recording period T, and is repeatedly generated for each recording period T.

[0081] The non-ejection vibration pulse NP1 is a driving waveform that vibrates the piezoelectric actuator 43 so that ink droplets are not ejected from the nozzle 35, and in the present embodiment, is a trapezoidal wave. Specifically, the non-ejection vibration pulse NP1 includes a first non-ejection expansion element P1 that expands the volume of the pressure chamber 44 from a reference volume by applying the first potential V1 from the intermediate potential Vm, a first non-ejection expansion maintaining element P2 that maintains the volume of the pressure chamber 44 expanded by the first non-ejection expansion element P1 for a fixed time, and a first non-ejection recovery element P3 that recovers the pressure chamber 44 from the expanded state of the first potential V1 to the reference volume of the intermediate potential Vm.

[0082] When such a non-ejection vibration pulse NP1 is supplied to the piezoelectric actuator 43, the piezoelectric actuator 43 performs non-ejection vibration, i.e., so-called micro-vibration, so that ink droplets are not ejected from the nozzle 35. That is, the first potential V1 of the non-ejection vibration pulse NP1 is set to a potential at which ink droplets are not ejected from the nozzle 35.

[0083] When such a non-ejection vibration pulse NP1 is supplied to the piezoelectric actuator 43 and the piezoelectric actuator 43 performs non-ejection vibration, heat is generated by heat generated by the vibration of the piezoelectric actuator 43 itself, heat generated by power consumption of the piezoelectric actuator 43, heat generated by the drive circuit 52, heat generated by the flow of ink, etc. Therefore, the inside of the ejection section 2 can be heated by causing the piezoelectric actuator 43 to perform non-ejection vibration, thereby warming the ink flowing into the ejection section 2. In addition, although the nozzle surface 37 of the nozzle plate 36 or the meniscus of the ink in the nozzle 35 is particularly easy to cool, since the piezoelectric actuator 43 is caused to perform non-ejection vibration by the non-ejection vibration pulse NP1, the ink in the pressure chamber 44 and the nozzle 35 is stirred, so that the temperature deviation of the ink in the pressure chamber 44 can be suppressed.

[0084] The printer controller 210 controls the supply of the non-ejection vibration pulse NP1 to the piezoelectric actuator 43 based on the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 during the standby period other than the printing operation period. That is, when the temperature detected by the temperature detection unit 219 during the standby period is lower than a predetermined temperature (also referred to as a threshold value), the printer controller 210 controls the drive circuit 52 in such a manner that the non-ejection vibration pulse NP1 is supplied to the piezoelectric actuator 43. In addition, when the temperature detected by the temperature detection unit 219 during the standby period is higher than a predetermined temperature (also referred to as a threshold value), the printer controller 210 controls the drive circuit 52 in such a manner that the non-ejection vibration pulse NP1 is not supplied to the piezoelectric actuator 43.

[0085] like Figure 5 As shown in FIG. 2 , the second drive signal COM2 is repeatedly generated by the drive signal generating unit 216 for a unit period T specified by a clock signal sent from the oscillation circuit 215. The unit period T is also called an ejection period T or a recording period T, and corresponds to one pixel of an image or the like printed on the printing medium S. In the present embodiment, the second drive signal COM2 is a signal having an ejection vibration pulse DP for driving the piezoelectric actuator 43 in a manner that ink droplets are ejected from the nozzle 35 and a non-ejection vibration pulse NP2 for driving the piezoelectric actuator 43 in a manner that ink droplets are not ejected from the nozzle 35 in one recording period T, and is repeatedly generated for each recording period T.

[0086] The discharge vibration pulse DP includes a first expansion element P11 , a first expansion maintaining element P12 , a first contraction element P13 , a first contraction maintaining element P14 , and a first recovery element P15 .

[0087] The first expansion element P11 is applied from the intermediate potential Vm to the second potential V2, thereby expanding the volume of the pressure chamber 44 from the reference volume. The first expansion maintenance element P12 maintains the volume of the pressure chamber 44 expanded by the first expansion element P11 for a fixed time. The first contraction element P13 is applied from the second potential V2 to the third potential V3, thereby contracting the volume of the pressure chamber 44. The first contraction maintenance element P14 maintains the volume of the pressure chamber 44 contracted by the first contraction element P13 for a fixed time. The first recovery element P15 recovers the pressure chamber 44 from the contracted state of the third potential V3 to the reference volume of the intermediate potential Vm.

[0088] When such an ejection vibration pulse DP is supplied to the piezoelectric actuator 43, the piezoelectric actuator 43 is deformed in a direction to expand the volume of the pressure chamber 44 by the first expansion element P11, so that the meniscus in the nozzle 35 is pulled to the pressure chamber 44 side, and the ink is supplied to the pressure chamber 44 from the common liquid chamber 47 side. In addition, the expansion state of the pressure chamber 44 is maintained by the first expansion maintaining element P12. Thereafter, the first contraction element P13 is supplied, so that the pressure chamber 44 is rapidly contracted from the expansion volume to the contraction volume corresponding to the third potential V3, thereby pressurizing the ink in the pressure chamber 44 and ejecting the ink droplets from the nozzle 35. The contraction state of the pressure chamber 44 is maintained by the first contraction maintaining element P14, and during this period, the ink pressure in the pressure chamber 44, which is reduced by the ejection of the ink droplets, rises again by the natural vibration. The first return element P15 is supplied according to the rising timing, and the pressure chamber 44 is returned to the reference volume, thereby absorbing the pressure fluctuation in the pressure chamber 44 .

[0089] The non-ejection vibration pulse NP2 during printing is a driving waveform for driving the piezoelectric actuator 43 in a manner that does not eject ink droplets from the nozzle 35, and in the present embodiment, is a trapezoidal wave. Specifically, the non-ejection vibration pulse NP2 during printing includes a second non-ejection expansion element P21 that expands the volume of the pressure chamber 44 from a reference volume by applying the fourth potential V4 from the intermediate potential Vm, a second non-ejection expansion maintaining element P22 that maintains the volume of the pressure chamber 44 expanded by the second non-ejection expansion element P21 for a fixed time, and a second non-ejection recovery element P23 that recovers the pressure chamber 44 from the expanded state of the fourth potential V4 to the reference volume of the intermediate potential Vm.

[0090] When such a non-ejection vibration pulse NP2 in printing is supplied to the piezoelectric actuator 43, the piezoelectric actuator 43 performs non-ejection vibration, i.e., so-called micro-vibration, in such a manner that ink droplets are not ejected from the nozzle 35. That is, the fourth potential V4 of the non-ejection vibration pulse NP2 in printing is set at a potential at which ink droplets are not ejected from the nozzle 35. In addition, the fourth potential V4 of the non-ejection vibration pulse NP2 in printing may be the same potential as the first potential V1 of the non-ejection vibration pulse NP1, or may be a different potential. That is, the non-ejection vibration pulse NP1 and the non-ejection vibration pulse NP2 in printing may be the same driving waveform, or may be different driving waveforms. By the way, the non-ejection vibration pulse NP1 is a pulse supplied to the piezoelectric actuator 43 during the standby period other than the printing operation period, and the non-ejection vibration pulse NP2 in printing is a pulse supplied to the piezoelectric actuator 43 during the printing operation period. Therefore, the non-ejection vibration pulse NP1 and the in-printing non-ejection vibration pulse NP2 can be optimized according to the printing operation.

[0091] When such a non-ejection vibration pulse NP2 is supplied to the piezoelectric actuator 43 to make the piezoelectric actuator 43 perform non-ejection vibration, heat is generated by heat generated by the vibration of the piezoelectric actuator 43 itself, heat generated by power consumption of the piezoelectric actuator 43, heat generated by the drive circuit 52, heat generated by the flow of ink, etc., as with the non-ejection vibration pulse NP1. Therefore, by making the piezoelectric actuator 43 perform non-ejection vibration by the non-ejection vibration pulse NP2 during printing, the ink in the pressure chamber in the ejection section 2 can be heated, and the heated ink can be ejected. In addition, although the nozzle surface 37 of the nozzle plate 36 or the meniscus of the ink in the nozzle 35 is particularly easy to cool, since the piezoelectric actuator 43 performs non-ejection vibration by using the non-ejection vibration pulse NP2 during printing, the ink in the pressure chamber 44 and the nozzle 35 is stirred, the temperature deviation of the ink in the pressure chamber 44 can be suppressed.

[0092] The printer controller 210 controls the drive circuit 52 in such a manner that either the ejection vibration pulse DP or the non-ejection vibration pulse NP2 of the second drive signal COM2 is selectively supplied to the piezoelectric actuator 43 during the printing operation of printing an image on the printing medium S according to the printing data. That is, the printer controller 210 controls the drive circuit 52 in such a manner that the ejection vibration pulse DP is supplied to the piezoelectric actuator 43 corresponding to the nozzle 35 from which the ink droplets for printing the image on the printing medium S according to the printing data are ejected within one pixel (also referred to as one cycle) during the printing operation. In addition, the printer controller 210 controls the drive circuit 52 in such a manner that the non-ejection vibration pulse NP2 is supplied to the piezoelectric actuator 43 corresponding to the nozzle 35 from which the ink droplets for printing the image on the printing medium S according to the printing data are not ejected within one pixel (also referred to as one cycle) during the printing operation.

[0093] Here, refer to Figure 6 The printing operation period, the non-printing operation period and the standby period of this embodiment are described below. Figure 6 2 is a diagram for explaining the printing area and the non-printing area of ​​the inkjet recording apparatus 1 .

[0094] like Figure 6 As shown, on the printing medium S supported by the support table 9 of the inkjet recording apparatus 1, a printing range Sa where printing can be performed at the center and a non-printing range Sb extending around the printing range Sa and not being printed are set.

[0095] The ejection unit 2 is arranged so as to be able to reciprocate in the +X direction and the -X direction along the X axis relative to the printing medium S supported on the support table 9. Moreover, when printing starts, the ejection unit 2 starts from the initial position and performs printing by reciprocating along the X axis at a position opposite to the printing medium S on the Z axis, and returns to the initial position when printing is finished. At this time, the area where the ejection unit 2 is opposite to the printing range Sa of the printing medium S, that is, the position where the ejection unit 2 can spray ink drops on the printing range Sa is called the printing area A. In contrast, the position other than the area where the ejection unit 2 is opposite to the printing range Sa of the printing medium S is called the non-printing area B. The non-printing area B includes the non-printing range Sb of the printing medium S, the portion of the support table 9 where the printing medium S is not placed, and the initial position. In addition, the initial position refers to the place where the ejection unit 2 stops and waits for the printing command except during the printing operation period from the time when the power of the inkjet recording device 1 is turned on to the time when it is turned off.

[0096] The printing operation period refers to a period during which the discharge unit 2 moves within the printing area A to print an image.

[0097] The non-printing operation period refers to a period during which the discharge unit 2 moves in the non-printing area B from the time when the discharge unit 2 starts moving until it reaches the initial position after printing is completed.

[0098] The standby period refers to a period during which the ejection unit 2 stops and waits for a print command, except for a printing operation period, from when the ink jet recording apparatus 1 is powered on to when it is powered off.

[0099] Furthermore, the printer controller 210 controls the supply of the vibration pulse NP1 to the piezoelectric actuator 43 so that the vibration pulse NP1 is not ejected during the standby period other than the printing operation period. In addition, in the present embodiment, the printer controller 210 controls the supply of the vibration pulse NP1 to the piezoelectric actuator 43 so that the vibration pulse NP1 is not ejected during the non-printing operation period including the standby period.

[0100] Furthermore, as described above, the printer controller 210 controls the supply of the non-ejection vibration pulse NP1 to the piezoelectric actuator 43 based on the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 during the standby period other than the printing operation period, which is the non-printing operation period including the standby period in this embodiment. That is, when the temperature detected by the temperature detection unit 219 during the non-printing operation period is lower than a predetermined temperature (also referred to as a threshold value), the printer controller 210 controls the drive circuit 52 in such a manner that the non-ejection vibration pulse NP1 is supplied to the piezoelectric actuator 43. Furthermore, when the temperature detected by the temperature detection unit 219 during the standby period is higher than a predetermined temperature (also referred to as a threshold value), the printer controller 210 controls the drive circuit 52 in such a manner that the non-ejection vibration pulse NP1 is not supplied to the piezoelectric actuator 43.

[0101] Furthermore, during the printing operation, that is, in the printing area A, the printer controller 210 controls the supply of the vibration pulse NP2 to the piezoelectric actuator 43 so that the vibration pulse NP2 is not ejected during printing.

[0102] In addition, the printer controller 210 performs maintenance processing at an optimal timing during the printing operation or during the non-printing operation including the standby period. The maintenance processing referred to herein refers to processing for discharging the ink in the ejection unit 2 to the outside, for example, a suction operation of sucking the ink in the ejection unit 2 from the nozzle 35 by covering the nozzle 35 with the cap 11 and making the sealed space covered by the cap 11 negatively pressurized, or so-called flushing, etc., in which ink droplets are ejected toward an area other than the printing medium S. In addition, the ink in the flow path from the liquid container 3 to the ejection unit 2 can be pressurized to discharge the ink in the ejection unit 2. Then, after the ink in the ejection unit 2 is discharged, the nozzle surface 37 where the nozzle 35 is opened is wiped by the wiper 10, thereby wiping the ink attached to the nozzle surface 37. That is, the so-called maintenance processing includes a wiping process of wiping the nozzle surface 37 where the nozzle 35 is opened by the wiper 10. When such a wiping process is performed, if a non-ejection vibration pulse NP1 is supplied to the piezoelectric actuator 43 to make the piezoelectric actuator 43 perform non-ejection vibration, the ink in the nozzle 35 contacts the wiper 10 because the meniscus of the ink in the nozzle 35 is vibrating, and the meniscus of the ink is destroyed. In addition, even when the meniscus of the ink in the nozzle 35 is destroyed, the ink droplets are not normally ejected, which is the so-called nozzle leakage. Therefore, the printer controller 210 controls the piezoelectric actuator 43 so that the non-ejection vibration pulse NP1 is not supplied during the maintenance process. In this way, the situation that the meniscus of the ink in the nozzle 35 is destroyed can be suppressed, and the so-called nozzle leakage in which the ink droplets are not ejected during printing can be suppressed.

[0103] Here, refer to Figure 7 Next, a method for driving the inkjet recording device 1 will be described. Figure 7 2 is an example of a timing chart for explaining a driving method of the ink jet recording device 1 .

[0104] like Figure 7 As shown in FIG. 1 , a period T1 from when the power of the inkjet recording device 1 is turned on (conducted) to when printing starts is a standby period. During this period T1, the printer controller 210 controls the supply of the non-ejection vibration pulse NP1 to the piezoelectric actuator 43 based on the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219. That is, the printer controller 210 starts the control of the supply of the non-ejection vibration pulse NP1 according to the temperature of the ink based on the power-on operation of the inkjet recording device 1.

[0105] The period T2 from the start of printing to the end of printing includes a printing operation period in which the ejection unit 2 is located in the printing area A, and a non-printing operation period in which the ejection unit 2 is located in the non-printing area B. During the non-printing operation period T2, the printer controller 210 controls the supply of the vibration pulse NP1 to the piezoelectric actuator 43 so as not to eject the vibration pulse NP1 based on the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219. Specifically, during the non-printing operation period T2, when the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 is lower than a predetermined temperature (also referred to as a threshold), the printer controller 210 controls the drive circuit 52 so as not to eject the vibration pulse NP1 to the piezoelectric actuator 43. Furthermore, during the non-printing operation period, when the temperature detected by the temperature detection unit 219 is higher than a predetermined temperature (also referred to as a threshold), the printer controller 210 controls the drive circuit 52 so as not to eject the vibration pulse NP1 to the piezoelectric actuator 43. Furthermore, during the printing operation period of the period T2, the printer controller 210 controls the drive circuit 52 in such a manner that the non-ejection vibration pulse NP2 is supplied to the piezoelectric actuator 43 corresponding to the non-ejection pixel, that is, the nozzle 35 that does not eject ink droplets according to the printing data. Furthermore, during the printing operation period of the period T2, the printer controller 210 controls the drive circuit 52 in such a manner that the ejection vibration pulse DP is supplied to the piezoelectric actuator 43 corresponding to the ejection pixel, that is, the nozzle 35 that ejects ink droplets according to the printing data.

[0106] The period T3 from the end of printing to the start of maintenance processing is a standby period. During this period T3, the printer controller 210 controls the supply of the vibration pulse NP1 to the piezoelectric actuator 43 so as not to eject the vibration pulse NP1 based on the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219.

[0107] During the period T4 from the start of the maintenance process to the end of the maintenance process, since the wiper 10 is in contact with the nozzle surface 37, the printer controller 210 controls the drive circuit 52 so as not to supply the non-ejection vibration pulse NP1 to the piezoelectric actuator 43. That is, the printer controller 210 stops supplying the non-ejection vibration pulse NP1 to the piezoelectric actuator 43 during the period of performing the maintenance process even if the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 is lower than a predetermined temperature.

[0108] The period T5 from the end of the maintenance process to the power supply of the inkjet recording device 1 being cut off (turned off) is a standby period. During this period T5, the printer controller 210 controls the supply of the vibration pulse NP1 to the piezoelectric actuator 43 so as not to eject the vibration pulse NP1 based on the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219. That is, the printer controller 210 stops the supply of the vibration pulse NP1 based on the power supply of the inkjet recording device 1, thereby stopping the control of not ejecting the vibration pulse NP1 according to the temperature of the ink.

[0109] In addition, during the non-printing operation period when the ejection unit 2 is located in the non-printing area B in the period T2, the printer controller 210 may be configured not to supply the non-ejection vibration pulse NP1 to the piezoelectric actuator 43. That is, the printer controller 210 may be configured to control the supply of the non-ejection vibration pulse NP1 to the piezoelectric actuator 43 only in the standby period outside the printing operation period. In this way, during the non-printing operation period when the ejection unit 2 is located in the non-printing area B in the period T2, the printer controller 210 may be configured not to supply the non-ejection vibration pulse NP1 to the piezoelectric actuator 43, thereby suppressing the situation in which the meniscus of the ink in the nozzle 35 is destroyed due to the contact between the print medium S and the nozzle surface 37 during the non-printing operation period of the period T2. That is, since floating caused by curling of the print medium S is likely to occur at the end of the print medium S, the end of the print medium S is likely to contact the nozzle 35 when the ejection unit 2 is located in the non-printing operation period of the period T2. Furthermore, when the non-ejection vibration pulse NP1 is supplied to the piezoelectric actuator 43 to make the piezoelectric actuator 43 perform non-ejection vibration, the ink in the nozzle 35 is in contact with the printing medium S because the meniscus of the ink is vibrating, so the ink in the nozzle 35 is in contact with the printing medium S, and the meniscus of the ink is destroyed. Even if the ink drop is to be ejected in the state where the meniscus of the nozzle 35 is destroyed, the ink drop may not be ejected normally, so-called nozzle leakage. During the non-printing operation period T2 when the printing medium S is likely to contact the nozzle 35, by not supplying the non-ejection vibration pulse NP1 to the piezoelectric actuator 43, the situation that the meniscus of the ink in the nozzle 35 is destroyed can be suppressed, and the situation that the ink drop is not ejected during printing, so-called nozzle leakage, can be suppressed. Incidentally, since the non-printing operation period in which the ejection unit 2 is located in the non-printing area B during the period T2 is a short time, even if the non-ejection vibration pulse NP1 is not supplied during this period, the temperature drop of the ink in the pressure chamber 44 is low, and the influence on the ejection characteristics is small. In addition, by not supplying the non-ejection vibration pulse NP1 during the non-printing operation period in which the ejection unit 2 is located in the non-printing area B during the period T2, it is not necessary to have a contact object detection unit such as a sensor that detects a contact object that may contact the nozzle surface 37, thereby making it easy to control and reducing costs.

[0110] Here, further, refer to Figure 8 A specific example of the method for driving the inkjet recording device 1 of this embodiment will be described. Figure 8 1 is a flowchart for explaining a method for driving the ink jet recording device 1 .

[0111] like Figure 8As shown in FIG. 1 , when the power of the inkjet recording device 1 is turned on (conducted) in step S1, the printer controller 210 determines whether the temperature of the ink in the pressure chamber detected by the temperature detection unit 219 is above the threshold value in step S2. In step S2, when the temperature of the ink in the pressure chamber detected by the temperature detection unit 219 is above the threshold value (step S2: Yes), since it is not necessary to heat the ink in the pressure chamber 44, in step S3, the printer controller 210 controls the drive circuit 52 in such a manner that the non-ejection vibration pulse NP1 is not supplied to the piezoelectric actuator 43. As a result, the heat generated by the driving of the piezoelectric actuator 43, that is, the heating of the ink, is not performed.

[0112] In step S2, when the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 is lower than a predetermined temperature (hereinafter referred to as a threshold value) (step S2: No), in step S4, the printer controller 210 controls the drive circuit 52 so as to supply the non-ejection vibration pulse NP1 to the piezoelectric actuator 43. As a result, the piezoelectric actuator 43 generates heat by performing non-ejection vibration without ejecting the vibration pulse NP1, and the ink inside the ejection unit 2 is heated.

[0113] Next, in step S5, the printer controller 210 determines whether maintenance processing is required. If it is determined in step S5 that maintenance processing is required (step S5: Yes), in step S6, the printer controller 210 controls the supply of the non-ejection vibration pulse NP1 to the piezoelectric actuators 43 corresponding to all the nozzles 35 to stop the non-ejection vibration of the piezoelectric actuator 43. Thereafter, in step S7, the printer controller 210 performs maintenance processing. That is, the printer controller 210 stops the supply of the non-ejection vibration pulse NP1 to the piezoelectric actuator 43 during the period of performing maintenance processing even if the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 is lower than the threshold.

[0114] If it is determined in step S5 that maintenance processing is not necessary (step S5 : No), steps S6 and S7 are skipped.

[0115] Next, in step S8, it is determined whether the power of the inkjet recording apparatus 1 is turned off (off). If it is determined in step S8 that the power of the inkjet recording apparatus 1 is turned off (step S8: Yes), the process ends.

[0116] If the power of the inkjet recording device 1 is not turned off in step S8 (step S8: No), the printer controller 210 determines whether printing has started in step S9. If it is determined in step S9 that printing has not started (step S9: No), steps S2 to S9 are repeatedly executed. That is, steps S2 to S9 are processes performed during the standby period when printing has not started.

[0117] In step S9, when it is determined that printing has started (step S9: Yes), in step S10, the printer controller 210 determines whether the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 is greater than the threshold value. In step S10, when the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 is greater than the threshold value (step S10: Yes), since it is not necessary to heat the ink in the pressure chamber 44, in step S11, the printer controller 210 controls the drive circuit 52 so as not to supply the non-ejection vibration pulse NP1 to the piezoelectric actuator 43. As a result, the heat generated by the driving of the piezoelectric actuator 43, that is, the heating of the ink, is not performed.

[0118] In step S10, when the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 is lower than a predetermined temperature (hereinafter referred to as a threshold value) (step S10: No), in step S12, the printer controller 210 controls the drive circuit 52 so as not to supply the non-ejection vibration pulse NP1 to the piezoelectric actuator 43. Thus, the piezoelectric actuator 43 performs non-ejection vibration and generates heat by not ejecting the vibration pulse NP1, so that the ink inside the ejection unit 2 is heated.

[0119] Next, in step S13, the printer controller 210 determines whether the ejection unit 2 is located in the printing area A. In step S13, if it is determined that the ejection unit 2 is located in the non-printing area B (step S13: No), steps S10 to S13 are repeatedly executed. That is, when the ejection unit 2 is located in the non-printing area B, the control of not ejecting the vibration pulse NP1 in steps S10 to S13 is implemented.

[0120] In step S13, when it is determined that the ejection unit 2 is located in the printing area A (step S13: Yes), in step S14, the printer controller 210 controls the drive circuit 52 in such a manner that the non-ejection vibration pulse NP2 is supplied to the piezoelectric actuator 43 corresponding to the nozzle 35 that does not eject the ink droplet. That is, the printer controller 210 controls the drive circuit 52 in such a manner that the ejection vibration pulse DP is supplied to the piezoelectric actuator 43 corresponding to the nozzle 35 that ejects the ink droplet of the print image onto the print medium S according to the print data within one pixel (also one cycle) during the printing operation. In addition, the printer controller 210 controls the drive circuit 52 in such a manner that the non-ejection vibration pulse NP2 is supplied to the piezoelectric actuator 43 corresponding to the nozzle 35 that does not eject the ink droplet according to the print data within one pixel (also one cycle) during the printing operation. Thus, even during printing, the non-discharge vibration pulse NP2 during printing is supplied to the piezoelectric actuator 43 corresponding to the nozzle 35 not discharging ink droplets to cause the non-discharge vibration to generate heat, thereby heating the ink inside the discharge unit 2 .

[0121] Next, in step S15, the printer controller 210 determines whether printing has been completed. In step S15, if it is determined that printing has not been completed (step S15: No), steps S13 to S15 are repeatedly executed.

[0122] In step S15 , when it is determined that printing is completed (step S15 : Yes), steps S2 to S9 are repeatedly executed until the next printing starts.

[0123] As described above, the inkjet recording device 1 as an example of the liquid ejection device of the present embodiment includes the ejection unit 2 including the nozzle 35 for ejecting the ink as the liquid, the pressure chamber 44 connected to the nozzle 35, and the piezoelectric actuator 43 for applying pressure variation to the ink in the pressure chamber 44. In addition, the inkjet recording device 1 includes the drive signal generating unit 216 as the drive waveform generating unit for generating the first drive signal COM1, wherein the first drive signal COM1 is a drive waveform including the non-ejection vibration pulse NP1 for applying pressure variation to the ink in the pressure chamber 44 so that the ink is not ejected from the nozzle 35 when supplied to the piezoelectric actuator 43. Furthermore, the inkjet recording device 1 includes the printer controller 210 as the control unit for controlling the supply of the non-ejection vibration pulse NP1 to the piezoelectric actuator 43 according to the temperature of the ink in the pressure chamber 44.

[0124] In this way, by not ejecting the vibration pulse NP1 and making the piezoelectric actuator 43 perform non-ejection vibration, the ink in the ejection section 2 is heated and stirred, thereby suppressing the temperature deviation of the ink, maintaining the ink in the ejection section 2 at a predetermined temperature, and ejecting ink droplets with stable ejection characteristics. Therefore, it is possible to suppress the occurrence of deviations in the ejection characteristics of the ink droplets due to the temperature change of the ink, thereby suppressing the degradation of the printed image quality. In addition, since the piezoelectric actuator 43 can be made to heat the ink in the pressure chamber 44 without ejecting vibration, a heater or the like for heating the ink is not required, thereby suppressing the situation where the structure of the inkjet recording device 1 becomes complicated, and there is no need to set up a space for a heater or the like, thereby achieving miniaturization of the inkjet recording device 1.

[0125] In addition, in the ink jet recording device 1 of the present embodiment, the drive circuit 52 as a selection unit that selects one of supplying and not supplying the vibration pulse NP1 to the piezoelectric actuator 43 without ejecting the vibration pulse NP1, and the temperature detection unit 219 that detects the temperature of the ink as the liquid are provided. In addition, it is preferable that the printer controller 210 as a control unit controls the drive circuit 52 in such a manner that the vibration pulse NP1 without ejecting is supplied to the piezoelectric actuator 43 when the detection result of the temperature detection unit 219 is lower than a predetermined temperature, and the vibration pulse NP1 without ejecting is not supplied to the piezoelectric actuator 43 when the detection result of the temperature detection unit 219 is higher than the predetermined temperature. In this way, since the printer controller 210 controls the drive circuit 52 in such a manner that the vibration pulse NP1 without ejecting is supplied to the piezoelectric actuator 43 according to the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219, the temperature of the ink in the pressure chamber 44 can be maintained at the predetermined temperature. That is, when the detection result of the temperature detection unit 219 is higher than the predetermined temperature, the printer controller 210 can suppress the temperature of the ink in the pressure chamber 44 from being heated to a temperature higher than the predetermined temperature by not supplying the non-ejection vibration pulse NP1 to the piezoelectric actuator 43, thereby suppressing the occurrence of deviation in the temperature of the ink in the pressure chamber 44. Therefore, the temperature of the ink can be maintained at the predetermined temperature, thereby suppressing the occurrence of deviation in the ejection characteristics of the ink droplets.

[0126] In addition, in the inkjet recording device 1 of the present embodiment, a maintenance unit, i.e., a wiper 10 and a cap 11, are provided for performing maintenance processing to discharge the liquid, i.e., ink, in the ejection unit 2. Furthermore, it is preferable that the printer controller 210, i.e., a control unit, controls the drive circuit 52, i.e., a selection unit, in such a manner that, even if the detection result of the temperature detection unit 219 is lower than a predetermined temperature, the non-ejection vibration pulse NP1 is not supplied to the piezoelectric actuator 43 before the maintenance processing is performed. In this manner, when the maintenance processing, i.e., the wiping processing of wiping the nozzle surface 37 by the wiper 10 is performed, it is possible to suppress the destruction of the meniscus of the ink of the nozzle 35 due to the wiping processing by not supplying the non-ejection vibration pulse NP1 to the piezoelectric actuator 43, thereby suppressing the occurrence of poor ejection of ink droplets.

[0127] As described above, the inkjet recording device 1 as an example of the liquid ejection device of the present embodiment includes the ejection unit 2, the ejection unit 2 including the nozzle 35 for ejecting the ink as the liquid, the pressure chamber 44 connected to the nozzle 35, and the piezoelectric actuator 43 for applying pressure variation to the ink in the pressure chamber 44. In addition, the inkjet recording device 1 includes the drive waveform generating unit, i.e., the drive signal generating unit 216, which generates the drive signal as the drive waveform. The drive signal generating unit 216 generates the first drive signal COM1, which is a first drive waveform including the non-ejection vibration pulse NP1 that applies pressure variation to the ink in the pressure chamber 44 in a manner that does not eject the ink from the nozzle 35 when supplied to the piezoelectric actuator 43. In addition, the drive signal generating unit 216 generates a second drive signal COM2, which is a second drive waveform including a non-ejection vibration pulse NP2 for applying pressure variation to the ink in the pressure chamber 44 so as not to eject the ink from the nozzle 35 when supplied to the piezoelectric actuator 43, and an ejection vibration pulse DP for applying pressure variation to the ink in the pressure chamber 44 so as to eject the ink from the nozzle when supplied to the piezoelectric actuator 43. In addition, the inkjet recording device 1 includes a drive circuit 52 including a selection unit for selecting the supply and non-supply of the drive signal as the drive waveform to the piezoelectric actuator 43, and a temperature detection unit 219 for detecting the temperature of the ink. In addition, the inkjet recording device 1 includes a printer controller 210 as a control unit, and the printer controller 210 controls the drive circuit 52 in a manner that one of the non-ejection vibration pulse NP2 for printing and the ejection vibration pulse DP is supplied to the piezoelectric actuator 43 according to the print data during a printing operation of printing an image on the print medium S according to the print data. Furthermore, during the standby period outside the printing operation period, the printer controller 210 controls the drive circuit 52 so as to supply the vibration pulse NP1 to the piezoelectric actuator 43 based on the detection result of the temperature detection unit 219 so as not to discharge the vibration pulse NP1 .

[0128] In this way, during the standby period, the piezoelectric actuator 43 is made to perform non-ejection vibration by not ejecting the vibration pulse NP1, thereby heating and stirring the ink in the ejection section 2, thereby suppressing the temperature deviation of the ink, maintaining the ink in the ejection section 2 at a predetermined temperature, and ejecting the ink droplets with stable ejection characteristics. Therefore, it is possible to suppress the occurrence of deviations in the ejection characteristics of the ink droplets due to the temperature change of the ink, thereby suppressing the degradation of the printed image quality. In addition, since the piezoelectric actuator 43 can be made to heat the ink in the pressure chamber 44 without ejecting vibration, it is not necessary to provide a heater for heating the ink or a mechanism for circulating the heated ink, thereby suppressing the situation where the structure of the inkjet recording device 1 becomes complicated, and there is no need to provide a space for a heater, etc., thereby achieving miniaturization of the inkjet recording device 1. In addition, since the temperature of the ink in the ejection section 2 can be maintained at a predetermined temperature during the standby period, it is possible to shorten the time from receiving the print start command to starting the printing operation.

[0129] Furthermore, even during the printing operation, by causing the piezoelectric actuator 43 corresponding to the nozzle 35 that does not eject ink droplets to vibrate without ejecting the ink using the vibration pulse NP2 that does not eject the ink during the printing operation, the ink in the ejection section 2 can be heated and stirred to suppress the temperature deviation of the ink, and the ink in the ejection section 2 can be maintained at a predetermined temperature, and the ink droplets can be ejected with stable ejection characteristics. Therefore, it is possible to suppress the occurrence of deviations in the ejection characteristics of the ink droplets due to the temperature change of the ink, and thus it is possible to suppress the degradation of the printed image quality. In particular, by causing the piezoelectric actuator 43 corresponding to the dormant nozzle that does not eject the ink droplets due to the vibration pulse NP2 that does not eject the ink during the printing to vibrate without ejecting the ink, the ink is heated, and thus it is possible to suppress the deviation of the image quality with respect to the ambient temperature in large-format printing, mass printing, or printing of the center of a text line drawing in which the dormant time of the dormant nozzle that does not eject the ink droplets during printing becomes long, and printing of CAD. In addition, in time-consuming printing such as high-definition printing or multi-cycle, unidirectional, low-speed printing such as printing on curved surfaces of three-dimensional objects, the ink is heated by vibrating the piezoelectric actuator 43 corresponding to the dormant nozzle that does not eject ink droplets due to the failure to eject the vibration pulse NP2 during printing, thereby suppressing the deviation of the image quality relative to the ambient temperature.

[0130] In addition, since the non-ejection vibration pulse NP1 during the standby period and the non-ejection vibration pulse NP2 during the printing operation can be set to different driving waveforms, the non-ejection vibration pulse NP1 and the non-ejection vibration pulse NP2 during the printing operation can be optimized according to their respective conditions. Since the non-ejection vibration pulse NP1 is supplied to the piezoelectric actuator 43 during the standby period, for example, the non-ejection vibration pulse NP1 can be repeatedly generated in a shorter period so that the ink in the ejection section 2 is heated in a shorter time, or more than two non-ejection vibration pulses NP1 can be set in one recording cycle T. In addition, since the non-ejection vibration pulse NP2 during the printing operation is supplied to the piezoelectric actuator 43 during the printing operation, for example, it can be designed based on the resonance period Tc (Helmholtz vibration period Tc) of the pressure chamber 44 in a manner that does not affect the ejection vibration pulse DP of the next ink droplet.

[0131] In addition, in the inkjet recording device 1 of the present embodiment, it is preferable that the printer controller 210 as the control unit starts to control the supply of the non-ejection vibration pulse NP1 according to the temperature of the ink as the liquid based on the power-on operation of the inkjet recording device 1. According to this, since the ink in the ejection unit 2 can be maintained at a predetermined temperature immediately after the power of the inkjet recording device 1 is turned on, the standby period from receiving the printing command to starting the printing can be shortened compared to the case where the ink is heated after receiving the printing command.

[0132] In addition, in the inkjet recording apparatus 1 of the present embodiment, it is preferable that the printer controller 210 as the control unit stops the supply control of the non-ejection vibration pulse NP1 according to the temperature of the ink as the liquid by stopping the power supply of the inkjet recording apparatus 1. Accordingly, by stopping the supply control of the non-ejection vibration pulse NP1 along with the power supply stop of the inkjet recording apparatus 1, it is possible to suppress useless power consumption.

[0133] Furthermore, in the inkjet recording apparatus 1 of the present embodiment, it is preferable that the printer controller 210 as the control unit controls the drive circuit 52 as the selection unit in such a manner that, during the standby period, when the detection result of the temperature detection unit 219 is lower than a predetermined temperature, the non-ejection vibration pulse NP1 is supplied to the piezoelectric actuator 43, and when the detection result of the temperature detection unit 219 is higher than a predetermined temperature, the non-ejection vibration pulse NP1 is not supplied to the piezoelectric actuator 43. In this way, since the printer controller 210 controls the drive circuit 52 in such a manner that the vibration pulse NP1 is not supplied to the piezoelectric actuator 43 according to the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219, the temperature of the ink in the pressure chamber 44 can be maintained at a predetermined temperature. That is, when the detection result of the temperature detection unit 219 is higher than the predetermined temperature, the printer controller 210 can suppress the temperature of the ink in the pressure chamber 44 from being heated to a temperature higher than the predetermined temperature by not supplying the non-ejection vibration pulse NP1 to the piezoelectric actuator 43, thereby suppressing the occurrence of deviation in the temperature of the ink in the pressure chamber 44. Therefore, the temperature of the ink can be maintained at the predetermined temperature, thereby suppressing the occurrence of deviation in the ejection characteristics of the ink droplets.

[0134] In this way, in the present embodiment, since the ink in the ejection unit 2 is heated by not ejecting the vibration pulse NP1 or not ejecting the vibration pulse NP2 during printing, ultraviolet curing ink or solvent-based ink can be used as the ink used in the ejection unit 2. That is, although the ultraviolet curing ink or solvent-based ink has a relatively high viscosity at room temperature, since the ink with a high viscosity can be heated by not ejecting the vibration pulse NP1 or not ejecting the vibration pulse NP2 during printing, the viscosity can be reduced, and thus the ejection characteristics of the ink droplets can be suppressed from being degraded.

[0135] In addition, solvent-based ink refers to an ink whose main component of the solvent is an organic solvent, and is called solvent ink or non-aqueous ink. Solvent-based ink is an ink containing any one or more of glycol ethers, glycol ether esters, dibasic acid esters, ester solvents, hydrocarbon solvents, and alcohol solvents. In addition, ultraviolet curing ink refers to, for example, UV ink including monomers or oligomers that are cured by polymerization reaction by ultraviolet irradiation. The composition of ultraviolet curing ink can be listed as an ink containing any one of (meth)acrylates, (meth)acrylamides, and N-vinyl compounds as a polymerizable compound.

[0136] In addition, although in the above-mentioned Embodiment 1, when the temperature detected by the temperature detection unit 219 is above the threshold value, the control is performed in a manner that the non-ejection vibration pulse NP2 is supplied to the piezoelectric actuator 43, but it is not particularly limited to this. For example, it is also possible to set the drive signal generation unit 216 to correct and generate the non-ejection vibration pulse NP2 in the printing in a manner that the heat generation of the piezoelectric actuator 43 is different based on the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219. Here, refer to Fig. 9 The non-ejection vibration pulse NP2 corrected by the drive signal generating unit 216 will be described. Fig. 9 This is a drive waveform showing the correction in which the vibration pulse NP2 is not ejected during printing.

[0137] The driving signal generating unit 216 generates the non-ejection vibration pulse in the printing process in such a manner that the heat generated by the piezoelectric actuator 43 caused by the non-ejection vibration pulse NP2 in the printing process when the temperature is lower than the predetermined temperature of the ink in the pressure chamber 44 serving as a reference is greater than the heat generated by the piezoelectric actuator 43 in the printing process when the non-ejection vibration pulse NP2 in the printing process is higher than the predetermined temperature. That is, when the temperature of the ink in the pressure chamber 44 detected by the temperature detecting unit 219 is lower than the predetermined temperature, the ink in the pressure chamber 44 has a high viscosity and needs to be heated more, so the non-ejection vibration pulse NP2 in the printing process is corrected and generated in such a manner that the heat generated by the piezoelectric actuator 43 becomes larger. In addition, when the temperature of the ink in the pressure chamber 44 detected by the temperature detecting unit 219 is higher than the predetermined temperature, the ink in the pressure chamber 44 has a low viscosity and needs to be heated less, so the non-ejection vibration pulse NP2 in the printing process is corrected and generated in such a manner that the heat generated by the piezoelectric actuator 43 becomes smaller.

[0138] Specifically, if Fig. 9 As shown, when the temperature of the ink in the pressure chamber detected by the temperature detection unit 219 is within a predetermined temperature range, the drive signal generation unit 216 generates a standard non-ejection vibration pulse NP2 for printing and supplies the standard non-ejection vibration pulse NP2 for printing to the piezoelectric actuator 43.

[0139] In contrast, when the temperature detected by the temperature detection unit 219 is lower than the predetermined temperature range, the drive signal generation unit 216 generates the fourth potential V in such a manner that the pulse amplitude becomes larger than the standard non-ejection vibration pulse NP2. 4A The vibration pulse NP2A is not ejected during printing, and the fourth potential V 4AThe potential difference based on the intermediate potential Vm is greater than the potential of the fourth potential V4 of the standard non-ejection vibration pulse NP2 in printing. When the piezoelectric actuator 43 is driven by the non-ejection vibration pulse NP2A in printing, the heat generated by the piezoelectric actuator 43 becomes larger than the case where the piezoelectric actuator 43 is driven by the non-ejection vibration pulse NP2 in printing, which becomes the standard. Therefore, in the case where the temperature of the ink in the pressure chamber 44 is lower than the predetermined temperature range, the heat generated by the piezoelectric actuator 43 can be increased by the non-ejection vibration pulse NP2A in printing, so that the temperature of the ink can be heated to the desired temperature in a short time. That is, in the case where the temperature of the ink in the pressure chamber 44 is lower than the predetermined temperature range, even if the piezoelectric actuator 43 is driven by the non-ejection vibration pulse NP2 in printing, which becomes the standard, the heat generated by the piezoelectric actuator 43 is small, and it takes time before the ink reaches the desired temperature.

[0140] Furthermore, when the temperature detected by the temperature detection unit 219 is above a predetermined temperature range, the drive signal generation unit 216 generates a fourth potential V in such a manner that the pulse amplitude is smaller than the standard non-ejection vibration pulse NP2. 4B The vibration pulse NP2B is not ejected during printing, and the fourth potential V 4B The potential difference based on the intermediate potential Vm is smaller than the potential of the fourth potential V4 of the standard non-ejection vibration pulse NP2 in printing. When the piezoelectric actuator 43 is driven by the non-ejection vibration pulse NP2B in printing, the heat generated by the piezoelectric actuator 43 becomes smaller than the case where the piezoelectric actuator 43 is driven by the non-ejection vibration pulse NP2 in printing, which becomes the standard. Therefore, when the temperature of the ink in the pressure chamber 44 is above the predetermined temperature range, the heat generated by the piezoelectric actuator 43 can be reduced by the non-ejection vibration pulse NP2B in printing, thereby heating the temperature of the ink to the desired temperature. That is, when the temperature of the ink in the pressure chamber 44 is above the predetermined temperature range, when the piezoelectric actuator 43 is driven by the non-ejection vibration pulse NP2 in printing, which becomes the standard, the heat generated by the piezoelectric actuator 43 may be increased, thereby making the ink higher than the desired temperature.

[0141] In addition, although Fig. 9In the example shown, the piezoelectric actuator is driven by the standard non-ejection vibration pulse NP2 in printing in the case of a predetermined temperature range, but the present invention is not particularly limited thereto. For example, the following method may be adopted, that is, when the predetermined temperature is set to a value and the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 is above the predetermined temperature, the non-ejection vibration pulse NP2A in printing is generated, and when the temperature of the ink in the pressure chamber 44 detected by the temperature detection unit 219 is lower than the predetermined temperature, the non-ejection vibration pulse NP2B in printing is generated. In other words, the so-called "predetermined temperature" may be a temperature of a value in a predetermined range or a temperature of a single value.

[0142] As described above, it is preferred that the drive signal generating unit 216 as a drive waveform generating unit generates the vibration pulse NP2 not ejected during printing in the following manner, that is, during the printing action, the heat generated by the piezoelectric actuator 43 caused by the vibration pulse NP2 not ejected during printing when the detection result of the temperature detecting unit 219 is less than a predetermined temperature is greater than the heat generated by the piezoelectric actuator 43 caused by the vibration pulse NP2 not ejected during printing when the detection result of the temperature detecting unit 219 is above the predetermined temperature.

[0143] In this way, the driving signal generating unit 216 corrects and generates the non-ejection vibration pulse NP2 during printing based on the temperature of the ink in the pressure chamber 44 detected by the temperature detecting unit 219, thereby enabling the temperature of the ink in the ejection unit 2 to be more finely controlled. Therefore, the temperature of the ink in the ejection unit 2 can be maintained with high accuracy. Therefore, the temperature of the ink, that is, the viscosity of the ink, can be controlled with high accuracy, thereby suppressing the occurrence of deviations in the ejection characteristics of the ink droplets.

[0144] In addition, although in the above example, the drive signal generating unit 216 is set to adjust the fourth potential V4 of the non-ejection vibration pulse NP2 in printing, thereby adjusting the applied voltage applied to the piezoelectric actuator 43, it is not particularly limited to this. Since the applied voltage is determined by the potential difference between the fourth potential V4 and the intermediate potential Vm, it is also possible to adjust the intermediate potential Vm, thereby adjusting the applied voltage applied to the piezoelectric actuator 43. In other words, the drive signal generating unit 216 only needs to correct and generate the non-ejection vibration pulse NP2 in printing in such a way that the applied voltage applied to the piezoelectric actuator 43 becomes larger when the temperature of the ink detected by the temperature detecting unit 219 is lower than the predetermined temperature.

[0145] In addition, the drive signal generating unit 216 may adjust the slope of the second non-ejection expansion element P21 of the non-ejection vibration pulse NP2 in printing to adjust the heat generation of the piezoelectric actuator 43. In other words, the drive signal generating unit 216 may correct and generate the second non-ejection expansion element P21 in such a manner that the slope becomes larger when the temperature detected by the temperature detecting unit 219 is lower than the predetermined temperature range.

[0146] Furthermore, the following method may be adopted, that is, when the temperature of the ink detected by the temperature detection unit 219 is lower than a predetermined temperature, the drive signal generation unit 216 generates two or more vibration pulses NP2 that are not ejected during printing within one recording cycle T, thereby increasing the heat generated by the piezoelectric actuator 43. That is, when the temperature of the ink detected by the temperature detection unit 219 is lower than a predetermined temperature, the drive signal generation unit 216 increases the number of vibration pulses NP2 that are not ejected during printing generated within one recording cycle T, thereby increasing the heat generated by the piezoelectric actuator 43. Furthermore, when the temperature of the ink detected by the temperature detection unit 219 is higher than a predetermined temperature, the drive signal generation unit 216 reduces the number of vibration pulses NP2 that are not ejected during printing generated within one recording cycle T, thereby reducing the heat generated by the piezoelectric actuator 43. That is, the heat generated by the piezoelectric actuator 43 mentioned here refers to the heat generated per unit time (one recording cycle T).

[0147] Of course, the generation of the vibration pulse NP2 not ejected during printing corresponding to the temperature detected by the temperature detection unit 219 implemented by the drive signal generation unit 216 is not limited to the above-mentioned two stages or three stages of the generation of the vibration pulse NP2 not ejected during printing, and can also be set to more than four stages.

[0148] In addition, the following method may be adopted, that is, the drive signal generating unit 216 corrects the ejection vibration pulse DP based on the temperature of the ink in the pressure chamber 44 detected by the temperature detecting unit 219, similarly to the non-ejection vibration pulse NP2 in printing. That is, the drive signal generating unit 216 only needs to correct the applied voltage specified by the potential difference between the second potential V2 and the third potential V3 of the first contraction element P13 to become larger when the temperature of the ink in the pressure chamber 44 detected by the temperature detecting unit 219 is lower than the predetermined temperature. In addition, the drive signal generating unit 216 only needs to correct the applied voltage specified by the potential difference between the second potential V2 and the third potential V3 of the first contraction element P13 to become smaller when the temperature of the ink in the pressure chamber 44 detected by the temperature detecting unit 219 is higher than the predetermined temperature. Of course, even in the ejection vibration pulse DP, it is also possible to adjust the slope of the first contraction element P13 similarly to the non-ejection vibration pulse NP2 in printing.

[0149] Implementation Method 2

[0150] Fig.10 2 is a cross-sectional view of a main part of an ink jet recording apparatus 1 as an example of a liquid ejecting apparatus according to a second embodiment of the present invention. Fig.11 as well as Fig.12 2 is a side view of a main part of an ink jet recording apparatus 1 according to a second embodiment.

[0151] like Fig.10 as well as Fig.11 As shown, the ink jet recording apparatus 1 is provided with a contact object detection unit 60 that detects an object that may come into contact with the nozzle surface 37 of the nozzle 35 in which the ejection unit 2 is opened.

[0152] The contact object detection unit 60 includes a main body 61 and a flexible rod 62 composed of a coil spring or the like having a base end fixed to the main body 61. Such a contact object detection unit 60 is composed of a limit switch that detects a situation in which an object contacts the flexible rod 62 and causes the flexible rod 62 to fall. Such a contact object detection unit 60 is provided with two on each side of the +X direction and the -X direction, which are the moving directions of the conveying body 7, and a total of four. That is, the contact object detection unit 60 is arranged on the X-axis in a manner of sandwiching the ejection unit 2 therebetween. Among them, the two contact object detection units 60 provided on each side of the +X direction and the -X direction of the conveying body 7 are arranged side by side along the +Y direction.

[0153] Each contact object detection unit 60 is arranged so that the tip of the flexible rod 62 is at the same height as the nozzle surface 37 of the ejection unit 2 held by the conveying body 7 on the Z axis. Fig.11 As shown in FIG. 1 , even if the end of the printing medium S is lifted up to a height where it contacts the nozzle surface 37 in the −Z direction, if the end Sc of the printing medium S may contact the nozzle surface 37 due to the movement of the conveyor 7, the printing medium S is still moved. Fig.12 As shown, before the nozzle face 37 contacts the end Sc of the printing medium S, the flexible rod 62 of the contact object detection unit 60 contacts the end of the printing medium S and tilts, thereby detecting the contact object. Therefore, the contact object detection unit can detect the contact object that may contact the nozzle face.

[0154] Such a contact object detection unit 60 of the present embodiment can also function as a detection unit that detects an object that hinders the movement of the conveyance body 7 along the X-axis.

[0155] In addition, although in this embodiment, a switch-like device that detects an object in contact with the flexible rod 62 by tilting the flexible rod 62 is used as the contact object detection unit 60, the present invention is not particularly limited to this, and for example, a non-contact sensor such as an infrared sensor, an electrostatic capacitance sensor, an optical sensor, etc. can be used. In addition, the contact object detection unit 60 can also be set to detect the wiping action performed by the wiper 10.

[0156] Furthermore, when the contact object detection unit 60 detects a contact object that may be in contact with the nozzle surface 37, the printer controller 210 controls the piezoelectric actuator 43 so as not to supply the non-ejection vibration pulse NP1. This can prevent the meniscus of the ink in the nozzle 35 from being destroyed, thereby preventing the occurrence of the so-called nozzle leakage, in which ink droplets are not ejected during printing.

[0157] Similarly, the printer controller 210 controls in such a manner that even during the printing operation, when the contact object detection unit 60 detects a contact object that may come into contact with the nozzle surface 37, the non-printing ejection vibration pulse NP2 is not supplied to the piezoelectric actuator 43. This can prevent the meniscus of the ink of the nozzle 35 from being destroyed, thereby preventing the occurrence of the so-called nozzle leakage in which ink droplets are not ejected during printing.

[0158] As described above, the inkjet recording apparatus 1 of the present embodiment is provided with the contact object detection unit 60 for detecting an object that may contact the nozzle face 37 in which the nozzle 35 is opened. Furthermore, it is preferable that the printer controller 210 as the control unit controls the drive circuit 52 as the selection unit in such a manner that, even when the detection result of the temperature detection unit 219 is lower than a predetermined temperature, when the contact object detection unit 60 detects an object that may contact the nozzle face 37, the supply of the non-ejection vibration pulse NP1 to the piezoelectric actuator 43 is not performed. In this way, when there is an object in contact with the nozzle face 37, by setting the non-ejection vibration pulse NP1 not to be supplied to the piezoelectric actuator 43, it is possible to suppress the situation where the meniscus of the ink of the nozzle 35 is destroyed by the object in contact with the nozzle face 37, and further suppress the situation where the ejection of ink droplets is poor.

[0159] Other Implementations

[0160] Although one embodiment of the present invention has been described above, the basic structure of the present invention is not limited to the above structure.

[0161] For example, although in the above-mentioned first embodiment, the non-ejection vibration pulse NP1 of the first drive signal COM1, the ejection vibration pulse DP of the second drive signal COM2, and the non-ejection vibration pulse NP2 in printing are repeatedly generated for each identical recording cycle T, the present invention is not particularly limited thereto. For example, the non-ejection vibration pulse NP1 may be repeatedly generated for each cycle of the recording cycle T shorter than one pixel.

[0162] In addition, the ink may be heated in the liquid container 3 or between the liquid container 3 and the ejection unit 2 and supplied to the ejection unit 2. Even when the heated ink is supplied to the ejection unit 2 in this way, the temperature of the ink is lowered in the ejection unit 2 by the ambient temperature. Therefore, by heating the ink in the ejection unit 2 using the non-ejection vibration pulse NP1 and the non-ejection vibration pulse NP2 during printing, it is possible to suppress the occurrence of deviations in the ejection characteristics, thereby improving the quality of printed images.

[0163] In addition, the piezoelectric actuator 43 of the above-mentioned embodiment 1 may be, for example, a thin film type piezoelectric actuator 43 stacked along the Z axis by film formation and photolithography, or a thick film type piezoelectric actuator 43 formed by a method such as pasting green sheets. In addition, the piezoelectric actuator 43 may be a longitudinal vibration type piezoelectric actuator in which piezoelectric materials and electrode forming materials are alternately stacked in a direction intersecting the Z axis so as to expand and contract in the Z axis direction.

[0164] In addition, although in the above-mentioned inkjet recording device 1, an example is given of a device in which the ejection unit 2 is mounted on the conveying body 7 and moves in the +X direction and -X direction along the X-axis as the main scanning direction, the present invention is not particularly limited to this. For example, the present invention can also be applied to a so-called line recording device in which the ejection unit 2 is fixed and printing is performed by only moving the printing medium S in the +Y direction as the sub-scanning direction.

[0165] In addition, although in the above-mentioned inkjet recording device 1, with respect to the change of the relative position of the ejection unit 2 and the printing medium S in the +Y direction and the -Y direction, the printing medium S is transported along the Y axis which is the sub-scanning direction by the transport mechanism 4, the present invention is not particularly limited to this. For example, the present invention can also be applied to a so-called flatbed recording device in which the support table 9 and the printing medium S attached to the upper surface thereof are fixed, the moving mechanism 6 moves the ejection unit 2 in the +X direction and the -X direction along the X axis, and printing is performed while the moving mechanism 6 moves in the +Y direction which is the sub-scanning direction along the guide rail of the support table 9 (not shown) along the Y axis.

[0166] Moreover, the present invention is an invention that is broadly applicable to all liquid ejecting devices. For example, it can also be applied to liquid ejecting devices that use ejecting parts such as recording heads such as various inkjet recording heads used in image recording devices such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, electrode material ejecting heads used in electrode formation in organic EL displays, FEDs (field emission displays), etc., and bio-organic matter ejecting heads used in biochip manufacturing.

[0167] Explanation of symbols

[0168] 1… inkjet recording device (liquid ejection device); 2… ejection portion; 3… liquid container; 4… conveying mechanism; 4a… conveying roller; 5… control unit; 6… moving mechanism; 7… conveying body; 8… conveying belt; 9… support table; 10… wiper; 11… cap; 35… nozzle; 36… nozzle plate; 37… nozzle surface; 39… connecting plate; 40… pressure chamber forming substrate; 41… plastic substrate; 42… retaining frame; 43… piezoelectric actuator; 44… pressure chamber; 45… vibrating plate; 46 ... nozzle communication port; 47 ... common liquid chamber; 48 ... independent communication port; 49 ... introduction liquid chamber; 50 ... introduction port; 51 ... protection substrate; 52 ... drive circuit; 53 ... wiring substrate; 60 ... contact object detection unit; 61 ... main body; 62 ... flexible rod; 122 ... shift register; 122A ... first shift register; 122B ... second shift register; 123 ... latch circuit; 123A ... first latch circuit; 123B ... second latch circuit; 124 …level converter; 124A…first level converter; 124B…second level converter; 125…switch; 125A…first switch; 125B…second switch; 126…decoder; 127…control logic; 210…printer controller (control unit); 211…external interface; 212A…receiving buffer; 212B…intermediate buffer; 212C…output buffer; 214…control processing unit; 215…oscillation circuit; 216…drive signal generating unit; 218…internal interface; 219…temperature detecting unit; 220…printer engine; A…printing area; B…non-printing area; COM1…first drive signal (first drive waveform); COM2…second drive signal (second drive waveform); DP…ejection vibration pulse; NP1…no ejection vibration pulse; NP2, NP2A, NP2B…no ejection vibration pulse in printing; S…printing medium; Sa…printing range; Sb…non-printing range; Sc…end portion.

Claims

1. A liquid ejection device, characterized in that: have: a discharge unit including a nozzle for discharging liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for applying pressure variation to the liquid in the pressure chamber; a driving waveform generating unit that generates a driving waveform including a non-discharge vibration pulse that, when supplied to the piezoelectric actuator, applies pressure variation to the liquid in the pressure chamber so as not to discharge the liquid from the nozzle; a selection unit that selects one of supplying and not supplying the non-ejection vibration pulse to the piezoelectric actuator; a temperature detection unit for detecting the temperature of the liquid; a maintenance unit that performs maintenance processing for discharging the liquid in the ejection unit; a control unit that controls the supply of the non-ejection vibration pulse to the piezoelectric actuator according to the temperature of the liquid in the pressure chamber, The control unit controls the selection unit so that the non-ejection vibration pulse is not supplied to the piezoelectric actuator before the maintenance process is performed even if the detection result of the temperature detection unit is lower than a predetermined temperature.

2. The liquid ejection device according to claim 1, wherein: The control unit controls the selection unit in the following manner, that is, when the detection result of the temperature detection unit is lower than the predetermined temperature, the non-ejection vibration pulse is supplied to the piezoelectric actuator, and when the detection result of the temperature detection unit is higher than the predetermined temperature, the non-ejection vibration pulse is not supplied to the piezoelectric actuator.

3. The liquid ejection device according to claim 1 or 2, characterized in that: A contact object detection unit is provided, wherein the contact object detection unit detects an object that is likely to come into contact with a nozzle surface where the nozzle is opened, The control unit controls the selection unit in the following manner, that is, even when the detection result of the temperature detection unit is lower than the predetermined temperature, the non-ejection vibration pulse is not supplied to the piezoelectric actuator when the contact object detection unit detects an object that has the possibility of contacting the nozzle surface.

4. A liquid ejection device, characterized in that: have: a discharge unit including a nozzle for discharging liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for applying pressure variation to the liquid in the pressure chamber; a driving waveform generating unit for generating driving waveforms including a first driving waveform and a second driving waveform, wherein the first driving waveform includes a non-ejection vibration pulse for applying pressure variation to the liquid in the pressure chamber in such a manner that the liquid is not ejected from the nozzle when the first driving waveform is supplied to the piezoelectric actuator, and the second driving waveform includes an in-printing non-ejection vibration pulse for applying pressure variation to the liquid in the pressure chamber in such a manner that the liquid is not ejected from the nozzle when the second driving waveform is supplied to the piezoelectric actuator, and an ejection vibration pulse for applying pressure variation to the liquid in the pressure chamber in such a manner that the liquid is ejected from the nozzle when the second driving waveform is supplied to the piezoelectric actuator; a selection unit that selects one of supply and non-supply of the driving waveform to the piezoelectric actuator; A temperature detection unit, which detects the temperature of the liquid; a maintenance unit that performs maintenance processing for discharging the liquid in the ejection unit; a control unit that controls the selection unit in a manner that supplies one of the non-ejection vibration pulse and the ejection vibration pulse to the piezoelectric actuator according to the print data during a printing operation period for printing an image on a printing medium according to print data, and controls the selection unit in a manner that supplies the non-ejection vibration pulse to the piezoelectric actuator according to a detection result of the temperature detection unit during a standby period outside the printing operation period, The control unit controls the selection unit so that the non-ejection vibration pulse is not supplied to the piezoelectric actuator before the maintenance process is performed even if the detection result of the temperature detection unit is lower than a predetermined temperature.

5. The liquid ejection device according to claim 1 or 4, characterized in that: The control unit starts controlling the supply of the non-discharge vibration pulse according to the temperature of the liquid based on the power-on operation of the liquid discharge device.

6. The liquid ejection device according to claim 5, characterized in that: The control unit stops the control of supplying the non-discharge vibration pulse according to the temperature of the liquid based on the power supply of the liquid discharge device being stopped.

7. The liquid ejection device according to claim 4, characterized in that: The control unit controls the selection unit during the standby period in the following manner, that is, when the detection result of the temperature detection unit is lower than the predetermined temperature, the non-ejection vibration pulse is supplied to the piezoelectric actuator, and when the detection result of the temperature detection unit is higher than the predetermined temperature, the non-ejection vibration pulse is not supplied to the piezoelectric actuator.

8. The liquid ejection device according to claim 4 or 7, characterized in that: The driving waveform generating unit generates a vibration pulse that is not ejected during printing in the following manner during the printing action, i.e., the heat generated by the piezoelectric actuator caused by the vibration pulse that is not ejected during printing when the detection result of the temperature detecting unit is less than the predetermined temperature is greater than the heat generated by the piezoelectric actuator caused by the vibration pulse that is not ejected during printing when the detection result of the temperature detecting unit is above the predetermined temperature.

9. The liquid ejection device according to claim 1 or 4, characterized in that: The liquid is ultraviolet curable ink or solvent ink.

10. A method for driving a liquid ejection device, characterized in that: The liquid ejection device comprises: a discharge unit including a nozzle for discharging liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for applying pressure variation to the liquid in the pressure chamber; a driving waveform generating unit that generates a driving waveform including a non-discharge vibration pulse that, when supplied to the piezoelectric actuator, applies pressure variation to the liquid in the pressure chamber so as not to discharge the liquid from the nozzle; a selection unit that selects one of supplying and not supplying the non-ejection vibration pulse to the piezoelectric actuator; a temperature detection unit for detecting the temperature of the liquid; a maintenance unit that performs maintenance processing for discharging the liquid in the ejection unit, In the driving method of the liquid ejection device, controlling the supply of the non-ejection vibration pulse to the piezoelectric actuator according to the temperature of the liquid in the pressure chamber, The selection unit is controlled so that the non-ejection vibration pulse is not supplied to the piezoelectric actuator before the maintenance process is performed even if the detection result of the temperature detection unit is lower than a predetermined temperature.

11. A method for driving a liquid ejection device, characterized in that: The liquid ejection device comprises: a discharge unit including a nozzle for discharging liquid, a pressure chamber connected to the nozzle, and a piezoelectric actuator for applying pressure variation to the liquid in the pressure chamber; a driving waveform generating unit for generating driving waveforms including a first driving waveform and a second driving waveform, wherein the first driving waveform includes a non-ejection vibration pulse for applying pressure variation to the liquid in the pressure chamber in such a manner that the liquid is not ejected from the nozzle when the first driving waveform is supplied to the piezoelectric actuator, and the second driving waveform includes an in-printing non-ejection vibration pulse for applying pressure variation to the liquid in the pressure chamber in such a manner that the liquid is not ejected from the nozzle when the second driving waveform is supplied to the piezoelectric actuator, and an ejection vibration pulse for applying pressure variation to the liquid in the pressure chamber in such a manner that the liquid is ejected from the nozzle when the second driving waveform is supplied to the piezoelectric actuator; a selection unit that selects one of supplying and not supplying the non-ejection vibration pulse to the piezoelectric actuator; A temperature detection unit, which detects the temperature of the liquid; a maintenance unit that performs maintenance processing for discharging the liquid in the ejection unit, In the driving method of the liquid ejection device, During a printing operation period for printing an image on a printing medium according to printing data, one of the non-ejection vibration pulse and the ejection vibration pulse is supplied to the piezoelectric actuator according to the printing data, and during a standby period outside the printing operation period, the non-ejection vibration pulse is supplied to the piezoelectric actuator according to a detection result of the temperature detection unit, The selection unit is controlled so that the non-ejection vibration pulse is not supplied to the piezoelectric actuator before the maintenance process is performed even if the detection result of the temperature detection unit is lower than a predetermined temperature.

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