JP2011131518A - Liquid ejector and control method of liquid ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejector easily enabling gradation expression of wide range according to a selected ejection mode and a control method of the liquid ejector. <P>SOLUTION: An ejection drive pulse DP2 is a voltage waveform including a preliminary expansion part p6 for changing a volume of a pressure chamber by changing a potential, an expansion holding part p7 for holding the volume of the pressure chamber for a predetermined time by holding the second expansion potential VL2, a contraction part p8 for changing the volume of the pressure chamber by changing the potential, a contraction holding part p9 for holding the volume of the pressure chamber for a predetermined time by holding the second contraction potential VH2, a return part p10 for changing the volume of the pressure chamber by changing the potential so as to return. The contraction part has the first contraction element p8a in which the potential changes, a middle holding element p8b for holding the first middle potential VM1 which is a terminal potential of the first contraction element, and the second contraction element p8c in which the potential changes, and a drive signal generating circuit changes a time width Wc1 of the second contraction element according to the set ejection mode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus including a liquid ejecting head such as an ink jet recording head, and a control method thereof.

  The liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting liquid and ejects various liquids from the liquid ejecting head. As a representative example of this liquid ejecting apparatus, for example, an ink jet recording head (hereinafter simply referred to as a recording head) as a liquid ejecting head is provided, and droplet-like ink is recorded on recording paper or the like from the nozzles of the recording head. An image recording apparatus such as an ink jet printer (hereinafter simply referred to as a printer) that records an image or the like by ejecting or landing on a medium (a target to be ejected) can be given. In recent years, it is applied not only to this image recording apparatus but also to various manufacturing apparatuses. For example, in a display manufacturing apparatus such as a liquid crystal display, a plasma display, an organic EL (Electro Luminescence) display, or an FED (surface emitting display), various liquid materials such as coloring materials and electrodes are used as pixel formation regions and electrode formations. A liquid ejecting apparatus is used for ejecting an area or the like.

  In the liquid ejecting apparatus, a driving signal including a driving pulse (ejection pulse) is generated, and the generated driving pulse is applied to pressure generating means (for example, a piezoelectric vibrator or a heating element) to drive it. In some cases, a pressure change is applied to the liquid in the pressure generation chamber, and the liquid is ejected from a nozzle opening communicating with the pressure generation chamber using the pressure change. In the liquid ejecting apparatus configured to generate a plurality of driving pulses for driving the pressure generating means, a driving pulse set to generate satellites, and a driving pulse set to prevent generating satellites By applying a drive pulse selected according to image data to a pressure generating means from among a plurality of drive pulses including the image data, it is configured to prevent image deterioration and density unevenness due to satellite dots (for example, , See Patent Document 1).

JP 2007-190931 A

  However, in a liquid ejecting apparatus that ejects liquid by a driving pulse selected from the above-described driving pulses prepared in advance, the amount of liquid ejected on an ejection target (in accordance with the number and type of driving pulses ( Since the type of (dot size) is determined, the type of recording tone is limited.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid ejecting apparatus and a control method for the liquid ejecting apparatus that can easily express a wide gradation according to the selected ejection mode. It is to provide.

In order to achieve the above object, a liquid ejecting apparatus according to an aspect of the present invention provides a liquid ejecting head that applies pressure fluctuation to a pressure chamber by the operation of a pressure generating unit, and ejects liquid filled in the pressure chamber from a nozzle;
Drive signal generation means capable of generating a drive signal including an ejection drive pulse for driving the pressure generation means to eject liquid from the nozzle to the landing target, and
A liquid ejecting apparatus capable of switching a plurality of ejection modes having different shapes of dots formed by the liquid ejected from the nozzle landing on the landing target,
The ejection drive pulse is
A first changing section for changing the volume of the pressure chamber by changing the potential from the intermediate potential in the first direction;
A first hold unit that maintains the terminal potential of the first change unit and holds the pressure chamber volume for a certain period of time;
Following the first hold unit, a second change that changes the pressure volume changed by the first change unit by changing the potential in the second direction opposite to the first direction. And
A second hold unit that maintains the terminal potential of the second change unit and holds the pressure chamber volume for a certain period of time;
Following the second hold unit, a third change unit that changes the pressure chamber volume changed by the second change unit by changing the potential to return to the intermediate potential in the first direction. ,
Is a voltage waveform including
The second change unit follows the first hold unit, maintains the first change element whose potential changes in the second direction, and the terminal potential of the first change element following the first change element. An intermediate hold element, and a second change element that changes in potential in the second direction following the intermediate hold element;
The drive signal generating means changes a time width of the second change element according to a set injection mode.

  According to the above configuration, the injection drive pulse maintains the first change portion that changes the volume of the pressure chamber by changing the potential from the intermediate potential in the first direction, and the terminal potential of the first change portion. The first hold unit that holds the pressure chamber volume for a certain period of time, and the potential changes in the second direction, which is opposite to the first direction, following the first hold unit, and is changed by the first change unit. A second change unit that changes the pressure volume, a second hold unit that maintains the terminal potential of the second change unit and holds the pressure chamber volume for a certain period of time, and a second hold unit. A voltage waveform including a third change portion that changes the pressure chamber volume changed by the second change portion by changing the potential to return to the intermediate potential in the first direction, and the second change The first portion follows the first hold portion and the potential changes in the second direction. An intermediate holding element that maintains the terminal potential of the first changing element following the first changing element, and a second changing element that changes in potential in the second direction following the intermediate holding element. The drive signal generating means changes the time width of the second change element according to the set ejection mode, thereby separating the portion (satellite droplet or this satellite from the tail portion of the droplet ejected from the nozzle). It is possible to adjust the flight speed and spray weight of a mist smaller than a droplet. Thereby, the shape of the dot formed by landing on the landing target can be easily changed according to the selected ejection mode, and a wide gradation expression according to the selected ejection mode can be easily performed.

In the above configuration, when the period of pressure vibration generated in the liquid in the pressure chamber is Tc,
When the high temperature ejection mode for ejecting liquid is set in a state where the ambient temperature in the vicinity of the liquid ejection head is 35 ° C. or higher, the time width of the second change element is set to Tc / 2 or more and Tc or less. It is desirable.

  According to this configuration, when the period of the pressure vibration generated in the liquid in the pressure chamber is Tc, the ambient temperature in the vicinity of the liquid ejecting head is 35 ° C. or higher, that is, the mist is reduced due to a decrease in the viscosity of the liquid. When the high temperature injection mode, which is a mode for injecting liquid in a condition that tends to occur, is set, the time width of the second change element is set to Tc / 2 or more and Tc or less, so that the main droplet is ejected when the liquid is ejected. It is possible to suppress the generation of mist that is finer than satellite droplets that are separated from the following satellite droplets. It is possible to suppress deterioration in the image quality of the recorded image due to the occurrence of mist.

In the above configuration, when the period of pressure vibration generated in the liquid in the pressure chamber is Tc,
When the standard injection mode as a standard in the plurality of injection modes is set, it is preferable that the time width of the second change element is set to Tc / 3 or more and less than Tc / 2.

  According to this configuration, when the period of the pressure oscillation generated in the liquid in the pressure chamber is Tc and the standard injection mode is set, the time width of the second change element is Tc / 3 or more Tc / 2. Therefore, the flying speed of the ejected liquid is adjusted within a range suitable for the standard ejection mode. That is, the flying speed of the liquid can be increased within a range in which the generation of mist can be suppressed when the liquid is ejected. Thereby, it is possible to bring the landing positions of both of the landing targets closer to each other while separating the ejected liquid into main droplets and satellite droplets. As a result, it is possible to achieve both suppression of mist and improvement of the image quality of the recorded image.

In the above configuration, when the period of pressure vibration generated in the liquid in the pressure chamber is Tc,
When the high-resolution injection mode for performing injection at a resolution higher than the resolution of the standard injection mode as a standard in the plurality of injection modes is set, the time width of the second change element is Tc / 4 or more Tc / It is desirable to set it to less than 3.

  According to this configuration, when the period of the pressure vibration generated in the liquid in the pressure chamber is Tc, the high-resolution injection mode in which injection is performed with a resolution higher than the resolution of the standard injection mode that is initially set before switching the injection mode Is set to Tc / 4 or more and less than Tc / 3, the flying speed of the liquid to be ejected is higher than that in the standard ejection mode. As a result, the main droplet ejected from the nozzle at the time of ejecting the liquid and the satellite droplet separated from the main droplet and landing can be landed at a position away from the standard, and in the case of the standard ejection mode. In comparison, the weight of the main droplet can be reduced. As a result, it is possible to contribute to an increase in resolution of a recorded image or the like while suppressing the roughness (graininess felt visually) of the image or the like recorded on the landing target.

In the above configuration, when the period of pressure vibration generated in the liquid in the pressure chamber is Tc,
When the high coverage spray mode is set in which the liquid is landed over a wider range on the landing target than in the other spray modes, the time width of the second change element is set to be greater than 0 and less than Tc / 4. It is desirable.

  According to this configuration, when the period of the pressure vibration generated in the liquid in the pressure chamber is Tc, the high-coating injection mode is set in which the liquid is landed over a wider area on the landing target than in the other injection modes. Since the time width of the second change element is set to be greater than 0 and less than Tc / 4, the flying speed of the ejected droplet is the highest among the plurality of ejection modes, and is thereby ejected from the nozzle. The satellite droplets separated from the main droplet can be separated into a plurality of satellite droplets and the separated satellite droplets can be landed on the landing target. As a result, a wide area on the landing target can be covered with dots.

  Further, in the above configuration, when the high-resolution ejection mode is set in a state where the environmental temperature near the liquid ejection head is 35 ° C. or more, a notification that informs the user that the high-temperature ejection mode is set is issued. It is desirable to have a means.

  According to this configuration, when the high-resolution ejection mode is set in a state where the environmental temperature near the liquid ejection head is 35 ° C. or higher, the notification unit notifies the user that the high-temperature ejection mode is set. Therefore, it is possible to notify the user in advance that priority is given to the suppression of mist over higher resolution, and the reliability can be ensured.

Further, the control method of the liquid ejecting apparatus of the present invention includes a liquid ejecting head that applies pressure fluctuation to the pressure chamber by the operation of the pressure generating means, and ejects the liquid filled in the pressure chamber from the nozzle, and the pressure generating means. Drive signal generating means capable of generating a drive signal including an ejection drive pulse for driving and ejecting liquid from the nozzle to the landing target, and the liquid ejected from the nozzle is landed on the landing target A method of controlling a liquid ejecting apparatus capable of switching a plurality of ejecting modes having different shapes of dots formed as
The ejection drive pulse includes a first change unit that changes in potential from an intermediate potential in a first direction, a first hold unit that maintains a terminal potential of the first change unit, and the first hold unit. Following the above, a second change unit in which the potential changes in a second direction opposite to the first direction, a second hold unit that maintains the terminal potential of the second change unit, A voltage waveform including a second change unit, and a third change unit that changes to return the potential to the intermediate potential in the first direction.
The second change unit includes a first change element whose potential changes halfway in a second direction from a termination potential of the first hold unit, and an intermediate hold element that maintains the termination potential of the first change element. A second change element whose potential changes from the terminal potential of the first change element in the second direction,
A first changing step of changing the volume of the pressure chamber by the first changing unit;
A first holding step of holding the pressure chamber volume changed by the first changing step for a predetermined time by the first holding unit;
A second changing step of changing the pressure chamber volume changed by the first changing step by the second changing unit;
A second hold step of holding the pressure chamber volume changed by the second change step for a predetermined time by the second hold unit;
A third changing step of changing the pressure chamber volume changed by the second changing step by the third changing unit;
Including
The second change process is changed in the first change process in which the pressure chamber volume changed in the first change process is changed halfway by the first change element, and in the first change process. A hold process for holding the pressure chamber volume for a certain period of time, and a second change process for changing the pressure chamber volume held in the hold process by the second change element,
The time width in the second change process is changed according to the set injection mode.
According to this control method, the velocity of the portion (satellite droplet or mist) separated from the tail portion of the droplet ejected from the nozzle is changed only by changing the time width of the second change element in the ejection drive pulse. Can be made. Thereby, the shape of the dot formed by landing on the landing target can be easily changed according to the selected ejection mode, and a wide gradation expression according to the selected ejection mode can be easily performed.

FIG. 2 is a perspective view illustrating a schematic configuration of a printer. FIG. 3 is a perspective view of the recording head as viewed from the pressure generating unit side. FIG. 3 is a cross-sectional view of a main part for explaining the configuration of a recording head. 2 is a block diagram illustrating an electrical configuration of a printer. FIG. It is a wave form diagram explaining the structure of the drive signal for standard modes. It is sectional drawing of the nozzle vicinity explaining the movement of the meniscus at the time of ejecting ink from a nozzle opening. It is a wave form diagram explaining the structure of the drive signal for high resolution modes. It is a wave form diagram explaining the structure of the drive signal for high covering modes. 6 is a flowchart illustrating a flow of printing processing. It is a figure explaining the relationship between printing mode and dot shape.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the following, a case where the liquid ejecting apparatus of the present invention is applied to the ink jet recording apparatus shown in FIG.

  The printer 1 has a recording head 2 which is a kind of liquid ejecting head, a carriage 4 to which an ink cartridge 3 for storing ink (a kind of liquid in the present invention) is detachably attached, and a lower part of the recording head 2. A platen 5 provided, a carriage 4 on which the carriage 4 on which the recording head 2 is mounted is moved in the paper width direction of the recording paper 6 (a kind of landing target), and a paper feed direction that is a direction orthogonal to the paper width direction. And a paper feed mechanism 8 for conveying the recording paper 6 and the like. Here, the paper width direction is the main scanning direction (head scanning direction), and the paper feeding direction is the sub-scanning direction (that is, the direction orthogonal to the head scanning direction).

  The carriage 4 is attached while being supported by a guide rod 9 installed in the main scanning direction, and is configured to move in the main scanning direction along the guide rod 9 by the operation of the carriage moving mechanism 7. ing. The position of the carriage 4 in the main scanning direction is detected by the linear encoder 10, and a detection signal is transmitted as position information to the control unit 46 (see FIG. 4). Thereby, the control unit 46 can control the recording operation (jetting operation) and the like by the recording head 2 while recognizing the scanning position of the carriage 4 (recording head 2) based on the position information from the linear encoder 10. .

  A home position serving as a scanning base point is set in an end area outside the recording area within the moving range of the carriage 4 (right side in FIG. 1). In the home position in the present embodiment, a capping member 12 that seals the nozzle forming surface (nozzle plate 36: see FIG. 3) of the recording head 2 and a wiper member 13 for wiping the nozzle forming surface are arranged. Yes. The printer 1 moves forward when the carriage 4 (recording head 2) moves from the home position toward the opposite end, and when the carriage 4 returns from the opposite end to the home position. And so-called bidirectional recording in which characters, images, etc. are recorded on the recording paper 6 in both directions.

  Next, the configuration of the recording head 2 will be described. Here, FIG. 2 is a perspective view of the recording head 2 as viewed from the pressure generating unit side, and FIG. 3 is a cross-sectional view of the main part of the recording head 2. The illustrated recording head 2 is composed of a pressure generating unit (or actuator unit) 19 and a flow path unit 20, and these are integrated in an overlapped state. The pressure generating unit 19 includes a pressure generating chamber plate 22 for partitioning a piezoelectric vibrator 26 (corresponding to pressure generating means in the present invention), a diaphragm 27, and a pressure generating chamber (corresponding to a pressure chamber in the present invention) 21. Are laminated and integrated by firing or the like.

  Further, the flow path unit 20 is configured by stacking a supply port forming plate 32 in which the supply port 30 and the second communication port 31 are formed, and a reservoir plate 35 in which the reservoir 33 and the first communication port 34 are formed. Yes. A nozzle plate 36 having nozzle openings 28 (corresponding to the nozzles in the present invention) is provided on the surface of the reservoir plate 35 opposite to the supply port forming plate 32.

  The diaphragm 27 is made of an elastic plate material. A plurality of piezoelectric vibrators 26 are disposed on the outer surface of the vibration plate 27 on the side opposite to the pressure generation chambers 21 in a state corresponding to the pressure generation chambers 21. The illustrated piezoelectric vibrator 26 is a vibrator in a flexural vibration mode, and is configured with a piezoelectric body 26c sandwiched between a drive electrode 26a and a common electrode 26b. When a drive signal is applied to the drive electrode of the piezoelectric vibrator 26, an electric field corresponding to the potential difference is generated between the drive electrode 26a and the common electrode 26b. This electric field is applied to the piezoelectric body 26c, and is deformed according to the strength of the electric field applied with the piezoelectric body 26c.

  The pressure generation chamber plate 22 is made of a thin ceramic material plate having a thickness suitable for forming the pressure generation chamber 21, such as alumina or zirconia, and the space for partitioning the pressure generation chamber 21 has a plate thickness. It is formed in a state penetrating in the vertical direction. The pressure generating chambers 21 are elongated holes that are formed in a row at a constant pitch that is the same as the pitch of the nozzle openings 28 of the nozzle plate 36 and that are elongated in the left-right direction orthogonal to the row direction.

  The supply port forming plate 32 is a thin plate-like member made of a metal material such as stainless steel. As shown in FIG. 3, the supply port forming plate 32 has a plurality of supply ports 30 penetrating in the thickness direction. A second communication port 31 penetrating in the plate thickness direction is formed so as to correspond to the first communication port 34 of the reservoir plate 35. The supply port 30 is a portion that provides fluid resistance (flow resistance) to ink in the ink flow path (liquid flow path). Regarding the supply port 30, the diameter on the reservoir 33 side is wider than the diameter on the pressure generation chamber 21 side. The supply port 30 is formed by press working. The supply port forming plate 32 is formed with a compliance portion 38 whose thickness is sufficiently thinner than other portions. The compliance portion 38 is manufactured by recessing the region corresponding to the reservoir 33 of the reservoir plate 35 by etching or the like from the surface opposite to the reservoir 33 in the plate thickness direction to form a recess 39.

  The reservoir plate 35 is a plate-like member made of a metal material such as stainless steel. The reservoir plate 35 is formed with an empty portion for partitioning the reservoir 33 in a state of penetrating the plate thickness direction. This empty portion defines the reservoir 33. The reservoir 33 is a part that functions as a liquid chamber common to the plurality of pressure generating chambers 21, and is provided for each type (color) of ink, and stores the ink supplied from the ink cartridge 3. The reservoir plate 35 is formed with a plurality of first communication ports 34 penetrating in the plate thickness direction so as to correspond to the second communication ports 31.

  The nozzle plate 36 is a plate-like member made of a metal material such as stainless steel. In the nozzle plate 36, a plurality of nozzle openings 28 are arranged in a row to form a nozzle array (nozzle opening group). In this embodiment, the nozzle arrays are opened at a constant pitch (for example, 180 dpi). 180 nozzle openings 28 are formed. The nozzle plate 36 may be made of an organic plastic film or the like in addition to the metal material.

  Each plate member is integrally joined between the pressure generating unit 19 and the supply port forming plate 32, between the supply port forming plate 32 and the reservoir plate 35, and between the reservoir plate 35 and the nozzle plate 36. It becomes. Thereby, as shown in FIG. 3, the reservoir 33 and the other end of the pressure generating chamber 21 communicate with each other through the supply port 30. Further, one end of the pressure generating chamber 21 and the nozzle opening 28 communicate with each other through the first communication port 34 of the reservoir plate 35 and the second communication port 31 of the supply port forming plate 32. A series of ink flow paths (liquid flow paths) that connect the pressure generation unit 19 and the nozzle openings 28 from the reservoir 33 through the pressure generation chamber 21 is formed for each nozzle opening 28.

  In the recording head 2 configured as described above, by deforming the piezoelectric vibrator 26, the corresponding pressure generation chamber 21 contracts or expands, and pressure fluctuation occurs in the ink in the pressure generation chamber 21. By controlling the ink pressure, it is possible to eject (discharge) ink from the nozzle opening 28. When the pressure generating chamber 21 having a constant volume is preliminarily expanded prior to discharging ink, the ink is supplied into the pressure generating chamber 21 through the supply port 30 from the reservoir 33 side. Further, when the pressure generating chamber 21 is rapidly contracted after the preliminary expansion, ink is ejected from the nozzle opening 28.

Next, the electrical configuration of the printer 1 will be described.
FIG. 4 is a block diagram illustrating an electrical configuration of the printer 1. The printer 1 in this embodiment is schematically configured by a printer controller 40 and a print engine 41. The printer controller 40 includes an external interface (external I / F) 42 for receiving print data from an external device such as a host computer, a RAM 43 for storing various data, a control routine for various data processing, and the like. A stored ROM 44, a control unit 46 for controlling each unit, an oscillation circuit 47 for generating a clock signal, and a drive signal generation circuit 48 for generating a drive signal to be supplied to the recording head 2 (in the drive signal generating means in the present invention) Equivalent), an internal interface (internal I / F) 49 for outputting to the recording head 2 pixel data and drive signals obtained by developing the print data for each dot, and the vicinity of the recording head 2 (periphery) A temperature sensor 55 for measuring the environmental temperature of the camera, and an image quality alarm 56 (notification in the present invention) to notify the user. It has an equivalent) to the stage.

  The control unit 46 outputs a head control signal for controlling the operation of the recording head 2 to the recording head 2, and outputs a control signal for generating the driving signal COM to the driving signal generation circuit 48. The head control signal is, for example, a transfer clock CLK, pixel data SI, a latch signal LAT, and a change signal CH1. These latch signals and change signals define the supply timing of each pulse constituting the drive signal COM.

  Further, the control unit 46 performs color conversion processing from the RGB color system to the CMY color system, halftone processing for reducing multi-gradation data to a predetermined gradation, and halftoned data based on the print data. The pixel data SI used for the ejection control of the recording head 2 is generated through a dot pattern development process in which the ink patterns (nozzle rows) are arranged in a predetermined arrangement and developed into dot pattern data. This pixel data SI is data relating to pixels of an image to be printed, and is a kind of ejection control information. Here, the pixel indicates a dot formation region that is virtually determined on a recording medium such as a recording paper to be landed. The pixel data SI according to the present invention includes gradation data relating to the presence / absence of dots formed on a recording medium (or presence / absence of ink ejection) and the size of dots (or the amount of ink ejected). In the present embodiment, the pixel data SI is composed of binary gradation data having a total of 2 bits. For the 2-bit gradation value, [00] corresponding to non-recording (fine vibration) in which ink is not ejected, [01] corresponding to recording of small dots, and [10] corresponding to recording of medium dots. [11] corresponding to large dot recording. Therefore, the printer according to the present embodiment can record with four gradations.

  Next, the configuration on the print engine 41 side will be described. The print engine 41 includes the recording head 2, a carriage moving mechanism 7, a paper feed mechanism 8, and a linear encoder 10. The recording head 2 includes a plurality of shift registers (SR) 50, latches 51, decoders 52, level shifters (LS) 53, switches 54, and piezoelectric vibrators 26 corresponding to the respective nozzle openings 28. Pixel data (SI) from the printer controller 40 is serially transmitted to the shift register 50 in synchronization with the clock signal (CK) from the oscillation circuit 47.

  A latch 51 is electrically connected to the shift register 50. When a latch signal (LAT) from the printer controller 40 is input to the latch 51, the pixel data of the shift register 50 is latched. The pixel data latched by the latch 51 is input to the decoder 52. The decoder 52 translates 2-bit pixel data to generate pulse selection data. The pulse selection data in this embodiment is composed of data of a total of 2 bits.

  Then, the decoder 52 outputs the pulse selection data to the level shifter 53 when receiving the latch signal (LAT) or the channel signal (CH). In this case, the pulse selection data is input to the level shifter 53 in order from the upper bit. The level shifter 53 functions as a voltage amplifier. When the pulse selection data is “1”, the level shifter 53 outputs an electric signal boosted to a voltage capable of driving the switch 54, for example, a voltage of about several tens of volts. The pulse selection data “1” boosted by the level shifter 53 is supplied to the switch 54. The drive signal COM from the drive signal generation circuit 48 is supplied to the input side of the switch 54, and the piezoelectric vibrator 26 is connected to the output side of the switch 54.

  The pulse selection data controls the operation of the switch 54, that is, the supply of the ejection pulse in the drive signal to the piezoelectric vibrator 26. For example, during a period in which the pulse selection data input to the switch 54 is “1”, the switch 54 is in a connected state, and the corresponding ejection pulse is supplied to the piezoelectric vibrator 26 and follows the waveform of the ejection pulse. Thus, the potential level of the piezoelectric vibrator 26 changes. On the other hand, during the period when the pulse selection data is “0”, the level shifter 53 does not output an electrical signal for operating the switch 54. For this reason, the switch 54 is in a disconnected state, and no ejection pulse is supplied to the piezoelectric vibrator 26.

  Here, the printer 1 according to the present invention is set by the user from four types of printing modes (equivalent to the ejection mode in the present invention) of a standard printing mode, a high resolution printing mode, a high covering printing mode, and a high temperature printing mode. It is configured to be able to switch to the (selected) print mode, and by changing the time width of the second contraction element of an ejection drive pulse to be described later according to the set print mode, the nozzle opening 28 can be changed. The dots formed by the ejected ink landing on the recording paper 6 are configured to have different shapes. Next, the configuration of the drive signal COM used in each print mode will be described.

FIG. 5 is a waveform diagram for explaining the configuration of the standard print mode drive signal generated by the drive signal generation circuit 48.
The standard print mode drive signal COM1 is a drive signal used in a print mode that is initially set as a standard mode in each print mode, and includes three ejection drive pulses DP1 (DP11, DP12, DP13). And a single injection drive pulse DP2, a total of two types of injection drive pulses DP1 and DP2 are included in a unit period delimited by the LAT signal. The first contraction potential VH2 of the ejection drive pulse DP2 is a potential corresponding to the state in which the piezoelectric vibrator 26 is displaced toward the pressure generation chamber 21 and contracts the pressure generation chamber 21, and the first expansion potential VL2 is The electric potential corresponding to the state in which the piezoelectric vibrator 26 is displaced to the side opposite to the pressure generation chamber 21 and the pressure generation chamber 21 is expanded. Further, the phase before the ejection drive pulses DP1 and DP2 (front side) in the unit period is opposite to the vibration of the ink in the pressure generation chamber 21 by the ejection drive pulses DP1 and DP2 in the unit period before the unit period. This is configured to include a cut pulse DPC that suppresses vibration of the ink in the pressure generating chamber 21 by applying the vibration to the pressure generating chamber 21.

  The ejection drive pulse DP1 is used to form middle-sized middle dots in a configuration in which multi-tone recording is performed by changing the size of the dots, such as large dots, middle dots, and small dots, for example. This is a middle dot ejection driving pulse. The ejection drive pulse DP1 changes in potential from the reference potential VB (corresponding to the intermediate potential) to the first expansion potential VL1 (VL1 <VL2) in the minus side (first direction), and the preliminary expansion expands the pressure generating chamber 21. Part p1, expansion maintaining part p2 that maintains the first expansion potential VL1 for a certain period of time, and the potential changes from the first expansion potential VL1 to the first contraction potential VH1 (VH1> VH2) on the plus side (second direction). The contraction part p3 that rapidly contracts the pressure generating chamber 21, the contraction maintenance (vibration hold) part p4 that maintains the first contraction potential VH1 for a certain time, and the potential returns from the first contraction potential VH1 to the reference potential VB. And an expansion return part p5.

  When the ejection drive pulse DP1 having the above configuration is applied to the piezoelectric vibrator 26, first, the piezoelectric vibrator 26 is bent in a direction away from the pressure generating chamber 21 by the preliminary expansion portion p1, thereby causing the pressure generating chamber 21 to be at the reference potential. It expands from the reference volume corresponding to VB to the expansion volume corresponding to the first expansion potential VL1. Due to this expansion, the ink surface (meniscus) in the nozzle opening 28 is largely drawn to the pressure generating chamber 21 side, and ink is supplied into the pressure generating chamber 21 from the reservoir 33 side through the supply port 30. And the expansion state of this pressure generation chamber 21 is maintained over the supply period of the expansion maintenance part p2. After the expanded state by the expansion maintaining part p2 is maintained, the contracted part p3 is supplied, and the piezoelectric vibrator 26 bends to the pressure generating chamber 21 side accordingly. Due to the displacement of the piezoelectric vibrator 26, the pressure generating chamber 21 is rapidly contracted from the expansion volume to the contraction volume. As a result, the ink in the pressure generating chamber 21 is pressurized, the central portion of the meniscus is pushed out to the ejection side, and the pushed portion extends like a liquid column.

  Thereafter, the contraction state of the pressure generating chamber 21 is maintained for a certain time by the contraction maintaining unit p4. During this time, the liquid column portion at the center of the meniscus separates from the meniscus and is ejected as ink droplets from the nozzle openings 28. The ink droplets land on the recording paper 6 to form dots having a size corresponding to the middle dots. Then, the pressure of the ink in the pressure generation chamber 21 that has decreased due to the ejection of ink rises again due to its natural vibration. The return expansion portion p5 is applied to the piezoelectric vibrator 26 in accordance with the rising timing, and the pressure generating chamber 21 expands and returns from the contracted volume to the steady volume.

  The ejection driving pulse DP2 is a molding injection pulse for forming a smallest mold in multi-gradation recording, and the potential changes from the reference potential VB to the second expansion potential VL2 in the minus side, resulting in a pressure generation chamber. A pre-expansion part p6 (first change part) that inflates 21; an expansion maintenance part p7 (first hold part) that maintains the second expansion potential VL2 for a fixed time; and a second contraction potential from the second expansion potential VL2. A contraction part p8 (second change part) that rapidly contracts the pressure generating chamber 21 by changing the potential to the plus side up to VH2, and a contraction maintenance (vibration hold) part p9 that maintains the second contraction potential VH2 for a certain period of time. (Second hold part) and a return expansion part p10 (third change part) in which the potential returns from the second contraction potential VH2 to the reference potential VB.

  The contraction part p8 has a first contraction element p8a (corresponding to the first change element) in which the potential changes (increases) in the positive direction from the second expansion potential VL2, and a terminal potential of the first contraction element p8a. An intermediate sustaining element p8b (corresponding to the intermediate hold element) that holds the intermediate potential VM1 for a certain time, and a second contraction element p8c (first) in which the potential changes (rises) in the positive direction from the first intermediate potential VM1 to the second contraction potential VH2. (Corresponding to 2 change factors). That is, the contraction part p8 is configured to stop the potential change for a short time while the potential changes from the second expansion potential VL2 to the second contraction potential VH2.

  The time from the start to the end of the second contraction element p8c, that is, the hold time Wc1 (eg, 1.68 μs) is Tc / 3 when the vibration period of the pressure vibration generated in the ink in the pressure generation chamber 21 is Tc. Thus, it is set to be less than Tc / 2. Note that the potential gradient (potential change amount per unit time) θ1 of the second contraction element p8c in the injection pulse DP2 is the potential gradient of second contraction elements p8f and p8g of the injection pulses DP4 and DP6 described later (in FIGS. 7 and 8). Are set to be smaller than those indicated by θ2 and θ3. Thus, the flying speed Vm1 of the ink ejected from the nozzle opening 28 using the ejection pulse DP2 is configured to be lower than the flying speed of the ink ejected by the ejection pulses DP4 and DP6.

The natural vibration period Tc can be expressed by the following equation (1), for example.
Tc = 2π√ [[(Mn × Ms) / (Mn + Ms)] × Cc] (1)
In Expression (1), Mn represents inertance at the nozzle opening 28, Ms represents inertance of the communication ports 31 and 34 and the supply port 30, and Cc represents compliance of the pressure generating chamber 21 (volume change per unit pressure, degree of softness). .)
In the above equation (1), inertance M indicates the ease of ink movement in the ink flow path, and is the mass of ink per unit cross-sectional area. Then, assuming that the density of the ink is ρ, the cross-sectional area of the surface orthogonal to the ink flow direction of the flow path is S, and the length of the flow path is L, the inertance M can be expressed by the following equation (2). it can.
Inertance M = (density ρ × length L) / cross-sectional area S (2)
In addition to the equation (1), any vibration cycle may be used as long as the pressure generating chamber 21 has.

  When the ejection drive pulse DP2 having the above configuration is supplied (applied) to the piezoelectric vibrator 26, first, the piezoelectric vibrator 26 is bent in a direction away from the pressure generating chamber 21 by the pre-expansion portion p6. Expands from the reference volume corresponding to the reference potential VB to the expansion volume corresponding to the second expansion potential VL2 (first changing step). 6A, the ink surface (meniscus) in the nozzle opening 28 is largely drawn to the pressure generating chamber 21 side (the upper side in the drawing), and the reservoir 33 is placed in the pressure generating chamber 21. Ink is supplied from the side through the supply port 30. And the expansion state of this pressure generation chamber 21 is maintained over the supply period of the expansion maintenance part p7 (1st hold process).

  After the expanded state by the expansion maintaining part p7 is maintained, the contracted part p8 is supplied, and the piezoelectric vibrator 26 bends to the pressure generating chamber 21 side accordingly. Due to the displacement of the piezoelectric vibrator 26, the pressure generating chamber 21 is contracted from the expansion volume to the contraction volume corresponding to the second contraction potential VH2 (second changing step). As described above, the contraction part p8 is composed of the first contraction element p8a, the intermediate element p8b, and the second contraction element p8c. Therefore, in this second changing step, the pressure generation chamber is generated by the first contraction element p8a. 21 is contracted from the expansion volume to the first intermediate volume corresponding to the first intermediate potential VM1 (first change process). As a result, the ink in the pressure generating chamber 21 is pressurized, and the central portion of the meniscus is pushed out to the ejection side (lower side in the drawing) as shown in FIG. It grows like a pillar.

  Subsequently, the intermediate maintenance element p8b is supplied, and the first intermediate volume is maintained (hold process). Thereby, the displacement of the piezoelectric vibrator 26 is temporarily stopped. During this time, as shown in FIG. 6C, the liquid column at the center of the meniscus extends in the ejection direction due to the inertial force, but during this time, the ink in the pressure generating chamber 21 is not pressurized, and accordingly, the liquid column extends. Is suppressed. As a result, the flying speed Vm1 of the main droplet Md ejected thereafter is suppressed.

  After the hold by the intermediate maintenance element p8b, the pressure generation chamber 21 is contracted from the first intermediate volume to the contraction volume by the second contraction element p8c (second change process). Then, as shown in FIG. 6 (d), the entire meniscus is pushed out in the ejection direction, and the rear end portion of the liquid column is slightly accelerated. Then, the meniscus and the liquid column are separated, and the separated portion is ejected as an ink droplet from the nozzle opening 28 and flies. The ejected ink droplet is composed of a preceding main droplet Md and a satellite droplet Sd that is separated from the main droplet Md and follows. Here, by adjusting the time width of the second contraction element p8c in the ejection drive pulse, it is possible to control the flying speed of the ink ejected from the nozzle opening 28, and thus the formation of the landing dot and the mist. In the ejection drive pulse DP2, since the time width Wc1 of the second contraction element p8c is set to Tc / 3 or more and less than Tc / 2, mist is generated while the ejected ink is separated into the main droplet and the satellite droplet. The flight speed is adjusted within the range to be prevented. That is, in the ejection driving pulse DP2, when the main droplet Md and the satellite droplet Sd are separated, generation of mist finer than the satellite droplet Sd is suppressed. Then, the satellite droplet Sd is slightly separated from the main droplet Md while flying toward the recording paper 6, so that the main droplet Md is separated from the recording paper 6 as shown in FIG. After landing first and forming the dot Dm, the satellite droplet Sd is landed at a position slightly away from the dot Dm to form the dot Ds. By intentionally separating the ink droplets ejected from the nozzle openings 28 into main droplets and satellite droplets, each droplet is landed on the recording paper 6 as compared with the case where the ink droplets are not separated. Therefore, it is possible to reduce the roughness of the recorded image, that is, the graininess that is visually perceived.

  After the contraction part p8, the contraction state of the pressure generation chamber 21 is maintained for a certain time by the contraction maintenance part p9 (second hold process). During this time, the pressure of the ink in the pressure generation chamber 21 that has decreased due to the ejection of ink rises again due to its natural vibration. The return expansion part p10 is applied to the piezoelectric vibrator 26 in accordance with this rising timing, and the pressure generating chamber 21 expands and returns from the contracted volume to the steady volume (third changing step). Thereby, the pressure fluctuation (residual vibration) of the ink in the pressure generating chamber 21 is reduced. As described above, in the standard printing mode using the ejection driving pulse DP2, it is possible to achieve both suppression of mist and improvement of the image quality of the recorded image.

FIG. 7 is a waveform diagram illustrating the configuration of the high resolution print mode drive signal generated by the drive signal generation circuit 48.
The high-resolution print mode drive signal COM2 is a drive signal used in a print mode in which ejection is performed at a resolution higher than the resolution of the standard print mode drive signal COM1, and includes two ejection drive pulses DP3 (DP31 and DP32). A total of two types of injection drive pulses DP3 and DP4 of one injection drive pulse DP4 are included in a unit period divided by the LAT signal. The interval t2 from the end of the return expansion portion p5 of the previous ejection driving pulse DP31 to the beginning of the next ejection driving pulse DP4 in the high resolution printing mode driving signal COM2 is ejected before the standard printing mode driving signal COM1. It is set to be longer than the interval t1 (see FIG. 5) from the end of the return expansion part p5 of the drive pulse DP11 to the start of the next ejection drive pulse DP12. Thereby, after the piezoelectric vibrator 26 is driven by the ejection drive pulse DP, the residual vibration remaining in the ink in the pressure generating chamber 21 is reduced.

The basic waveform configuration of the ejection drive pulse DP3 is substantially the same as that of the ejection drive pulse DP1, but the configurations of the preliminary expansion part p11, the expansion maintaining part p12, and the contraction part p13 are different.
The pre-expansion part p11 is set so as to have a longer time width than the pre-expansion part p1 of the injection drive pulse DP1, and the pressure changes from the reference potential VB to the first expansion potential VL1 in the negative direction. 21 is expanded more slowly than the preliminary expansion part p1. The expansion maintaining unit p12 is set to have a shorter time width than the expansion maintaining unit p1 of the ejection drive pulse DP1, and maintains the first expansion potential VL1 for a short time. The contraction part p13 is set so that the time width is shorter than the contraction part p3 of the ejection drive pulse DP1, and the pressure changes from the first expansion potential VL1 to the first contraction potential VH1 to the plus side. 21 is contracted more rapidly than the contraction part p3. The ejection drive pulse DP3 having this configuration secures the ejection weight of the ink and reduces the residual vibration remaining in the ink in the pressure generating chamber 21 when the piezoelectric vibrator 26 is driven more than the ejection drive pulse DP1. It is configured.

The basic waveform configuration of the ejection drive pulse DP4 is substantially the same as that of the ejection drive pulse DP2, but the configuration of the contraction part p8 is different.
The contraction part p8 of the ejection drive pulse DP4 is the first contraction element p8d (corresponding to the first change element) in which the potential changes (falls) in the negative direction from the expansion potential VH2, and the terminal potential of the first contraction element p8d. An intermediate sustaining element p8e (corresponding to the intermediate holding element) that holds the second intermediate potential VM2 (VM2 <VM1) for a certain period of time, and a second contraction element p8f that changes (falls) in the negative direction from the second intermediate potential VM2. (Corresponding to the second change element). That is, the contraction part p8 is configured to stop the potential change for a short time while the potential changes from the second expansion potential VH2 to the second contraction potential VL2.

  The time from the start end to the end of the second contraction element p8f, that is, the hold time Wc2 (eg, 1.28 μs) is Tc / 4 when the vibration period of the pressure vibration generated in the ink in the pressure generation chamber 21 is Tc. As described above, it is set to be less than Tc / 3. The potential gradient sign θ2 of the second contraction element p8f in the ejection pulse P4 is set to be larger than the potential gradient θ1 of the second contraction element p8c in the ejection pulse P2. Thereby, the flying speed Vm2 of the ink ejected from the nozzle opening 28 using the ejection pulse P4 is configured to be higher than the flying speed Vm1 of the ink ejected by the ejection pulse P2.

  When the ejection driving pulse DP4 having the above configuration is supplied (applied) to the piezoelectric vibrator 26, the potential gradient θ2 of the second contraction element p8f is larger than the potential gradient θ1 of the second contraction element p8c of the ejection pulse P2. Therefore, the main droplet Md ejected from the nozzle opening 28 and the satellite droplet Sd separated from the main droplet Md and succeeding the main droplet Md, as shown in FIG. Is landed at a position farther away than when it is supplied to the piezoelectric vibrator 26. Further, the ink weight of the main droplet Md can be reduced as compared with the case of the standard ejection mode. Thereby, it is possible to contribute to high resolution while further suppressing the roughness in the recorded image.

FIG. 8 is a waveform diagram for explaining the configuration of the high coverage printing mode drive signal generated by the drive signal generation circuit 48.
The high coverage printing mode driving signal COM3 is a driving signal used in a printing mode in which ink is landed on a wider area on the recording paper 6 than in the other ejection modes, and includes four ejection driving pulses DP5 (DP51, DP52, DP53). , DP54) and one injection drive pulse DP6, a total of two types of injection drive pulses DP5, DP6 are included in a unit period divided by the LAT signal. Note that the interval t3 from the end of the return expansion portion p17 of the previous (front) ejection drive pulse DP51 to the start of the next ejection drive pulse DP52 in the high clothes print mode drive signal COM3 is the standard print mode drive signal COM1. The interval t1 is set to be shorter than the interval t2 in the high-resolution print mode drive signal COM2. Thereby, the frequency of the ejection drive pulse within the unit cycle is increased.

The basic waveform configuration of the ejection drive pulse DP5 is substantially the same as that of the ejection drive pulses DP1 and DP3, but the third expansion potential VL3 (VL3 <VL1, VL2) and the third contraction potential VH3 (VH3> VH1, VH2). ) Is set to be higher than the drive voltage Vd1 (see FIGS. 5 and 7) of the ejection drive pulses DP1 and DP3, and the preliminary expansion part p13, the expansion maintaining part p14, and the contraction part p15. The configurations of the contraction maintaining unit p16 and the expansion return unit p17 are different.
The pre-expansion part p13 is set so that the time width is shorter than the pre-expansion part p1 of the injection drive pulse DP1, and the potential changes to the negative side from the reference potential VB to the first expansion potential VL3, and the pressure generating chamber 21 is expanded more slowly than the preliminary expansion part p1. The expansion maintaining unit p14 is set to have a shorter time width than the expansion maintaining unit p2 of the ejection drive pulse DP1, and maintains the first expansion potential VL3 for a certain period of time shorter than the expansion maintaining unit p2. The contraction part p15 is set so that the time width is shorter than the contraction part p3 of the ejection drive pulse DP1, and the pressure changes from the first expansion potential VL3 to the first contraction potential VH3 to the plus side. 21 is contracted more rapidly than the contraction part p3. The ejection drive pulse DP5 having this configuration is set such that the drive voltage Vd3 is higher than the drive voltage Vd1 of the ejection drive pulses DP1 and DP3, so that the weight of the ejected ink is increased and the unit period is increased. The frequency of the injection drive pulse is increased.

The basic waveform configuration of the ejection drive pulse DP6 is substantially the same as that of the ejection drive pulses DP2 and DP4, but the configuration of the contraction part p8 is different.
The contraction part p8 of the ejection drive pulse DP6 is the first contraction element p8d (corresponding to the first change element) in which the potential changes (falls) in the negative direction from the expansion potential VH2, and the terminal potential of the first contraction element p8d. An intermediate sustaining element p8e (corresponding to the intermediate holding element) that holds the second intermediate potential VM2 (VM2 <VM1) for a certain period of time, and a second contraction element p8g that changes (falls) in the negative direction from the second intermediate potential VM2. (Corresponding to the second change element). That is, the contraction part p8 is configured to stop the potential change for a short time while the potential changes from the second expansion potential VH2 to the second contraction potential VL2.

  The time from the start end to the end of the second contraction element p8g, that is, the hold time Wc3 (for example, 0.88 μs) is greater than 0 when the vibration period of the pressure vibration generated in the ink in the pressure generation chamber 21 is Tc. It is set to less than / 4. Note that the potential gradient of the second contraction element p8g in the injection pulse P6 (indicated by the symbol θ3 in FIG. 8) is larger than the potential gradients θ1 and θ2 of the second contraction elements p8c and p8f of the injection pulses P2 and P4. Is set to Accordingly, the flying speed Vm3 of the ink ejected from the nozzle opening 28 using the ejection pulse P6 is configured to be higher than the flying speeds Vm1 and Vm2 of the ink ejected by the ejection pulses P2 and P4.

  When the ejection drive pulse DP6 having the above configuration is supplied (applied) to the piezoelectric vibrator 26, the potential gradient θ3 of the second contraction element p8g becomes the potential gradient θ1, of the second contraction elements p8c and p8f of the ejection pulses P2 and P4. Since it is set to be larger than θ2, the flying speed is the highest in the ejection mode, and the satellite droplet Sd separated from the main droplet Md ejected from the nozzle opening 28 is separated into a plurality of the following. As shown in FIG. 10D, after the main droplet Md has landed first on the recording paper 6 to form the dots Dm, the separated satellite droplets Sd are separated from the dots Dm and A plurality of (three in the present embodiment) dots Ds1, Ds2, and Ds3 are formed by landing at positions spaced apart from each other. As a result, the wide area on the recording paper 6 can be covered with the landed dots Dm, Ds1, Ds2, and Ds3.

FIG. 9 is a flowchart for explaining the flow of the printing process.
First, a user designates and determines a print mode from four types of print modes, ie, a standard print mode, a high resolution print mode, a high coverage print mode, and a high temperature print mode (S1). If the type of recording paper is not specified, the standard print mode is automatically set.) Next, it is determined whether the environmental temperature in the vicinity of the recording head 2 measured by the temperature sensor 55 is 35 ° C. or higher (S2). When the environmental temperature in the vicinity of the recording head 2 is 35 ° C. or lower (S2: NO), the print mode determined by the user is confirmed (S3). When the standard print mode is designated (or when the standard print mode is automatically set) (S4), the drive signal generation circuit 48 generates the standard print mode drive signal COM1, and the user selects the high resolution print mode. Is designated (S5), the drive signal generation circuit 48 generates the high resolution print mode drive signal COM2, and when the user designates the high coverage print mode (S6), the drive signal generation circuit 48 A drive signal COM3 for high coverage printing mode is generated. When the designation of the print mode is completed (S4 to S6), the piezoelectric vibrator 26 is driven by the print mode drive signals COM1, COM2, and COM3 selected by the user, and the print process is executed (S7). .

  If the ambient temperature in the vicinity of the recording head 2 is 35 ° C. or higher (S2: YES), the high temperature printing mode is selected, and the drive signal generation circuit 48 generates the high temperature printing mode drive signal COM4 (S8). . Next, it is determined whether the print mode designated by the user is the high resolution print mode (S9). When the print mode designated by the user is the high-resolution print mode (S9: YES), the viscosity of the ink decreases in a high temperature environment, so that the ink ejected from the nozzle opening 28 lands on the recording paper 6. The user is notified that the dot shape (image quality) formed in this manner cannot be ensured by sounding the image quality alarm 56 (S10). As a result, the tail portion of the ink droplet ejected from the nozzle opening 28 is separated, so that a mist finer than the satellite droplet Sd separated from the main droplet Md is generated, and the resolution of the recorded image is increased. The user can be notified in advance that priority is given to the suppression of mist, and the reliability of image quality can be ensured. Thereafter, the piezoelectric vibrator 26 is driven by the high-temperature print mode drive signal COM4 to execute the printing process (S7). If the print mode designated by the user is other than the high-resolution print mode (S9: NO), the piezoelectric vibrator 26 is driven by the high-temperature print mode drive signal COM4 to execute the print process (S7). . In addition, regarding the image quality alarm 56, a configuration in which a message or an image is displayed on a display device by software stored in the printer 1 or an external device connected to the printer 1 to notify the user of the above contents. But it ’s okay.

  A high-temperature print mode drive signal COM4 (not shown) is a drive signal used in a print mode in which ink is ejected in a state where the environmental temperature near the recording head 2 is 35 ° C. or higher. Time from the start to the end of the second contraction elements p8c, p8f, and p8g of the ejection drive pulses DP2, DP4, and DP6 of the drive signals COM1, COM2, COM3, and COM4 used in the print modes and the high coverage printing modes. That is, the ejection drive pulse DP2 ′ in which the hold time Wc4 (for example, 2.08 μs) is changed to Tc / 2 or more and Tc or less when the vibration period of the pressure vibration generated in the ink in the pressure generation chamber 21 is Tc. , DP4 ′, DP6 ′ are included in a unit period delimited by the LAT signal.

  When the ejection drive pulses DP2 ′, DP4 ′, DP6 ′ having the above-described configuration are supplied (applied) to the piezoelectric vibrator 26, the hold time Wc4 of the ejection drive pulses DP2 ′, DP4 ′, DP6 ′ is changed to the ejection drive pulses DP2, 2. Since it is set so as to be longer than the hold times Wc1, Wc2, and Wc3 of DP4 and DP6, the flying speed of the ejected ink is suppressed, and as a result, a mist finer than the satellite droplet Sd may be generated. It is suppressed. Then, the satellite droplet Sd approaches the main droplet Md while flying toward the recording paper 6, and finally the main droplet Md becomes the recording paper 6 as shown in FIG. , The dot Dm is formed first, and then the satellite droplet Sd is landed at substantially the same position as the dot Dm to form the dot Ds. As a result, a dot Dm + Ds that is a combination of the dot Dm and the dot Ds is formed on the recording paper 6. As a result, even when the environmental temperature near the recording head 2 is 35 ° C. or higher, it is possible to prevent the image quality from being deteriorated due to the mist landing on the recording paper 6.

  In each of the above embodiments, the so-called flexural vibration type piezoelectric vibrator 26 is exemplified as the pressure generating means. However, the present invention is not limited to this, and for example, a so-called longitudinal vibration type piezoelectric vibrator can be employed. is there. In this case, with respect to the exemplified drive signal, the waveform changes in the direction of potential change, that is, upside down.

  The above has been described by taking the printer 1 which is a type of liquid ejecting apparatus as an example, but the present invention can also be applied to other liquid ejecting apparatuses. For example, a display manufacturing apparatus that manufactures color filters such as liquid crystal displays, an electrode manufacturing apparatus that forms electrodes such as organic EL (Electro Luminescence) displays and FEDs (surface emitting displays), and chips that manufacture biochips (biochemical elements) The present invention can also be applied to a manufacturing apparatus or the like.

DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Recording head, 6 ... Recording paper, 21 ... Pressure generating chamber, 26 ... Piezoelectric vibrator, 28 ... Nozzle opening, 48 ... Drive signal generation circuit, 56 ... Image quality alarm, COM ... Drive signal, DP ... Injection drive pulse

Claims (7)

A liquid ejecting head that applies pressure fluctuation to the pressure chamber by the operation of the pressure generating means, and ejects the liquid filled in the pressure chamber from the nozzle;
Drive signal generation means capable of generating a drive signal including an ejection drive pulse for driving the pressure generation means to eject liquid from the nozzle to the landing target, and
A liquid ejecting apparatus capable of switching a plurality of ejection modes having different shapes of dots formed by the liquid ejected from the nozzle landing on the landing target,
The ejection drive pulse is
A first changing section for changing the volume of the pressure chamber by changing the potential from the intermediate potential in the first direction;
A first hold unit that maintains the terminal potential of the first change unit and holds the pressure chamber volume for a certain period of time;
Following the first hold unit, a second change that changes the pressure volume changed by the first change unit by changing the potential in the second direction opposite to the first direction. And
A second hold unit that maintains the terminal potential of the second change unit and holds the pressure chamber volume for a certain period of time;
Following the second hold unit, a third change unit that changes the pressure chamber volume changed by the second change unit by changing the potential to return to the intermediate potential in the first direction. ,
Is a voltage waveform including
The second change unit follows the first hold unit, maintains the first change element whose potential changes in the second direction, and the terminal potential of the first change element following the first change element. An intermediate hold element, and a second change element that changes in potential in the second direction following the intermediate hold element;
The liquid ejecting apparatus according to claim 1, wherein the driving signal generating unit changes a time width of the second change element in accordance with a set ejection mode. When the period of pressure vibration generated in the liquid in the pressure chamber is Tc,
When the high temperature ejection mode for ejecting liquid is set in a state where the ambient temperature in the vicinity of the liquid ejection head is 35 ° C. or higher, the time width of the second change element is set to Tc / 2 or more and Tc or less. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. When the period of pressure vibration generated in the liquid in the pressure chamber is Tc,
The time width of the second change element is set to Tc / 3 or more and less than Tc / 2 when the standard injection mode as a standard in the plurality of injection modes is set. The liquid ejecting apparatus according to 1. When the period of pressure vibration generated in the liquid in the pressure chamber is Tc,
When the high-resolution injection mode for performing injection at a resolution higher than the resolution of the standard injection mode as a standard in the plurality of injection modes is set, the time width of the second change element is Tc / 4 or more Tc / The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is set to be less than 3. When the period of pressure vibration generated in the liquid in the pressure chamber is Tc,
When the high coverage spray mode is set in which the liquid is landed over a wider range on the landing target than in the other spray modes, the time width of the second change element is set to be greater than 0 and less than Tc / 4. The liquid ejecting apparatus according to claim 1, wherein:   In the state where the environmental temperature in the vicinity of the liquid ejecting head is 35 ° C. or more, when the high-resolution ejecting mode is set, a notification unit that informs a user that the high-temperature ejecting mode is set is provided. The liquid ejecting apparatus according to claim 5. A pressure fluctuation is applied to the pressure chamber by the operation of the pressure generating means, and a liquid ejecting head for ejecting the liquid filled in the pressure chamber from the nozzle; Drive signal generating means capable of generating a drive signal including an ejection drive pulse for ejecting, and a plurality of ejections having different shapes of dots formed by the liquid ejected from the nozzle landing on the landing target A control method of a liquid ejecting apparatus capable of switching modes,
The ejection drive pulse includes a first change unit that changes in potential from an intermediate potential in a first direction, a first hold unit that maintains a terminal potential of the first change unit, and the first hold unit. Following the above, a second change unit in which the potential changes in a second direction opposite to the first direction, a second hold unit that maintains the terminal potential of the second change unit, A voltage waveform including a second change unit, and a third change unit that changes to return the potential to the intermediate potential in the first direction.
The second change unit includes a first change element whose potential changes halfway in a second direction from a termination potential of the first hold unit, and an intermediate hold element that maintains the termination potential of the first change element. A second change element whose potential changes from the terminal potential of the first change element in the second direction,
A first changing step of changing the volume of the pressure chamber by the first changing unit;
A first holding step of holding the pressure chamber volume changed by the first changing step for a predetermined time by the first holding unit;
A second changing step of changing the pressure chamber volume changed by the first changing step by the second changing unit;
A second hold step of holding the pressure chamber volume changed by the second change step for a predetermined time by the second hold unit;
A third changing step of changing the pressure chamber volume changed by the second changing step by the third changing unit;
Including
The second change process is changed in the first change process in which the pressure chamber volume changed in the first change process is changed halfway by the first change element, and in the first change process. A hold process for holding the pressure chamber volume for a certain period of time, and a second change process for changing the pressure chamber volume held in the hold process by the second change element,
A method for controlling a liquid ejecting apparatus, comprising: changing a time width in the second change process in accordance with a set ejection mode.

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