JP2013022869A - Liquid jetting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jetting apparatus capable of reducing the length of a drive signal to attain higher frequency driving.SOLUTION: A printer that jets ink to a recording medium in both a going tine and a returning time of a recording head includes a driving signal generating circuit that includes, in at least one driving signal COM, middle dot driving pulses DPM1, DPM2 which are first driving voltages only for the going time, and a small dot driving pulse DPS which is a second driving voltage only for the returning time. The first driving voltage and the second driving voltage are in waveforms different from each other in the amount of ink jetted from the nozzle.

Description

  The present invention relates to a liquid ejecting apparatus such as an ink jet recording apparatus, and more particularly to a liquid ejecting apparatus capable of controlling liquid ejection while relatively moving a liquid ejecting head and a liquid landing target.

  The liquid ejecting apparatus includes a liquid ejecting head capable of ejecting liquid as droplets, and ejects various liquids from the liquid ejecting head. As a typical example of this liquid ejecting apparatus, for example, an ink jet recording apparatus that includes an ink jet recording head (hereinafter referred to as a recording head) and performs recording by ejecting liquid ink as ink droplets from the recording head ( And an image recording apparatus such as a printer. In recent years, the present invention is applied not only to this image recording apparatus but also to various manufacturing apparatuses such as a display manufacturing apparatus.

  As an ink jet printer that is a kind of the above liquid ejecting apparatus (hereinafter simply referred to as a printer), an ejection driving pulse (a kind of ejection driving voltage) is applied to pressure generating means such as a piezoelectric vibrator, and the pressure generating means is used. An ink jet recording head capable of ejecting ink from nozzles by being driven (a type of liquid ejecting head; hereinafter simply referred to as a recording head), and the width direction of a recording medium (liquid landing target) such as recording paper. That is, a head scanning mechanism capable of reciprocating in the main scanning direction and capable of so-called bidirectional recording in which ink droplets are ejected both when the recording head moves forward and when it moves backward is proposed. ing.

  In a printer capable of bidirectional recording, for example, a drive signal in which a plurality of types of ejection drive pulses with different amounts of ejected ink are connected in series is generated, and a necessary ejection drive pulse is selected from these drive signals. When recording is performed by forming dots of different sizes by supplying them to a pressure generating means such as a piezoelectric vibrator, that is, when performing so-called multi-gradation recording, during forward movement and during backward movement By reversing the order of application to the pressure generating means, the landing position relationship (dot formation position relationship) in the main scanning direction in the virtual pixel area on the recording medium is aligned during forward movement and backward movement. Yes. For example, when dots are formed in the order of middle dots and small dots in a predetermined pixel area during forward movement, dots are formed in the order of small dots and middle dots at the time of backward movement, so that the positional relationship of the small dots with respect to the middle dots ( (Or vice versa) is reciprocated.

  However, in the printer having such a configuration, since the ink is ejected while moving the recording head, an inertial component caused by the movement of the recording head acts on the ejected ink droplet, and the ink droplet is applied to the recording medium. Flying diagonally. When ejecting ink droplets having different flying speeds, for example, when ejecting ink droplets corresponding to the small dot and ink droplets corresponding to the middle dot, the droplets are ejected from the nozzles onto the recording paper. Since the time until landing is different for each ink drop, the flight distance in the main scanning direction is also different. Therefore, in this case, as shown in FIG. 6, the dot formation position in the main scanning direction in the pixel region P is different between forward movement and backward movement. When such a shift in the dot formation position occurs, there is a problem that banding (streaky noise) occurs in the recorded image and graininess (roughness of the image visually felt) increases.

  For this reason, by adjusting the waveform interval between ejection drive pulses included in the drive signal during forward movement and backward movement according to the difference in the flying speed of ink droplets, the dot formation position during forward movement and backward movement Have been proposed (see, for example, Patent Document 1).

JP 2002-225250 A

  However, the printer described above requires an adjustment allowance for adjusting the waveform interval between the ejection drive pulses, so that there is a problem that the entire drive signal becomes longer and the drive frequency decreases accordingly.

  Such a problem is not limited to an ink jet recording apparatus equipped with an ink jet recording head that ejects ink droplets, but also in a liquid ejecting apparatus equipped with other liquid ejecting heads that eject liquid droplets other than ink. Exists.

  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 that can shorten the length of a drive signal and can be driven at a higher frequency. is there.

A liquid ejecting apparatus of the present invention has been proposed to achieve the above object, and a liquid ejecting head that ejects liquid from a nozzle by driving a pressure generating unit;
Drive signal generation means for generating a drive signal including an injection drive voltage for driving the pressure generation means,
A liquid ejecting apparatus that relatively moves the liquid ejecting head with respect to a liquid landing target, and that ejects liquid onto the liquid landing target during both forward movement and backward movement,
The drive signal generation means includes a first drive signal used at the time of forward movement, and a second drive signal used at the time of backward movement in which the size of the liquid ejected from the nozzle is different from the first drive signal. Features.

According to the above configuration, since the injection process is performed only by the first drive signal during the forward movement and the injection process is performed only by the second drive signal during the backward movement, the injection drive voltage included in the first drive signal is reduced. Due to the influence of residual vibration when the liquid is ejected using, the ejection characteristics (the amount of liquid ejected from the nozzle or the flying speed) vary when ejecting the liquid using the ejection drive voltage included in the second drive signal There is nothing to do. Similarly, the residual vibration when the liquid is ejected using the ejection drive voltage of the first drive signal does not affect the ejection characteristics when the liquid is ejected using the ejection drive voltage of the second drive signal. . Thus, since it is not necessary to consider the influence of residual vibration between the first drive signal and the second drive signal, the length of the entire drive signal can be shortened accordingly. As a result, it is possible to drive at a higher frequency.
In addition, regarding the reciprocal landing position shift due to the difference in the flying speed of the liquid when the liquid is ejected using each ejection driving voltage, either the ejection driving voltage of the first driving signal or the ejection driving voltage of the second driving signal is used. It is possible to align the landing positions by adjusting one of the generation timings. Even in this case, since the timing can be adjusted without considering the influence of residual vibration, it is possible to contribute to shortening the entire length of the drive signal without unnecessarily widening the waveform interval.

  In the above configuration, the first drive signal has a first drive voltage, the second drive signal has a second drive voltage different from the first drive voltage, and a reference potential serving as a reference for potential change of the drive voltage is Different configurations may be adopted for the first drive signal and the second drive signal.

  In this way, even when the reference potential serving as a reference for the potential change of the ejection drive voltage is different between the first drive signal and the second drive signal, there is no switching of the drive signal at the time of forward movement or backward movement. This eliminates the time required for switching the signal system and the waveform components connecting different reference potentials. For this reason, the drive signal can be further shortened and the design freedom of the drive signal and the ejection drive voltage is improved.

2 is a block diagram illustrating an electrical configuration of a printer. FIG. 2 is a perspective view illustrating an internal configuration of the printer. FIG. FIG. 3 is a cross-sectional view of a main part of the recording head. FIG. 6 is a waveform diagram illustrating a configuration of a drive signal and a selection correspondence table of dot size and ejection drive pulse. It is a wave form diagram explaining the structure of the drive signal in 2nd Embodiment. FIG. 5 is a schematic diagram for explaining a shift in dot formation position in the main scanning direction during forward movement and backward movement.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described 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, an ink jet recording apparatus (hereinafter referred to as a printer) will be described as an example of the liquid ejecting apparatus of the invention.

FIG. 1 is a block diagram illustrating the electrical configuration of the printer 1. FIG. 2 is a perspective view illustrating the internal configuration of the printer 1.
The illustrated printer 1 ejects ink, which is a kind of liquid, toward a recording medium S such as recording paper, cloth, or resin film. The recording medium S is a kind of liquid landing target that is a target to which liquid is ejected and landed. A computer CP as an external device is connected to the printer 1 so as to be communicable. In order to cause the printer 1 to print an image, the computer CP transmits print data corresponding to the image to the printer 1.

  The printer 1 in this embodiment includes a transport mechanism 2, a carriage moving mechanism 3 (a kind of moving means), a drive signal generation circuit 4 (a kind of drive signal generation means), a head unit 5, a detector group 6, and a printer. It has a controller 7. The transport mechanism 2 transports the recording medium S in the transport direction. The carriage moving mechanism 3 moves the carriage to which the head unit 5 is attached in a predetermined movement direction (for example, the paper width direction). The drive signal generation circuit 4 includes a DAC (Digital Analog Converter) (not shown). Then, an analog voltage signal is generated based on the waveform data relating to the waveform of the drive signal sent from the printer controller 7. The drive signal generation circuit 4 also includes an amplifier circuit (not shown), and amplifies the voltage signal from the DAC to generate the drive signal COM. The drive signal COM is applied to the piezoelectric vibrator 32 (see FIG. 3) of the recording head 8 during a printing process (a kind of recording process or ejection process) for the recording medium S. As shown in FIG. 4, the drive signal COM is a signal including at least one ejection drive pulse within a unit period T that is a generation repetition cycle of the drive signal. Here, the ejection drive pulse is a type of ejection drive voltage that causes the piezoelectric vibrator 32 to perform a predetermined operation (operation such as expansion and contraction) in order to eject ink droplets from the nozzles 43 of the recording head 8. . Details of the drive signal COM will be described later.

  The head unit 5 includes a recording head 8 and a head control unit 11. The recording head 8 is a kind of liquid ejecting head, and ejects ink from the nozzles 43 toward the recording medium S, and a virtual region corresponding to a predetermined region of the recording medium S (a pixel that is a unit for forming an image or the like). ) To form dots. An image or the like is recorded on the recording medium S by arranging the dots in a matrix. The head controller 11 controls the recording head 8 based on the head control signal from the printer controller 7. The detector group 6 includes a plurality of detectors that monitor the status of the printer 1.

  The transport mechanism 2 is a mechanism for transporting the recording medium S in a direction orthogonal to the scanning direction of the recording head 8 (hereinafter referred to as a transport direction). The transport mechanism 2 includes a transport motor 14, a transport roller 15, and a platen 16. The transport roller 15 is a roller that transports the recording medium S to the platen 16 that is a printable area, and is driven by the transport motor 14. The platen 16 supports the recording medium S being printed.

  The printer controller 7 is a control unit for controlling the printer. The printer controller 7 includes an interface unit 24, a CPU 25, and a memory 26 (a type of storage unit). The interface unit 24 transmits and receives data between the computer CP that is an external device and the printer 1. The CPU 25 is an arithmetic processing unit for controlling the entire printer. The memory 26 is for securing an area for storing a program of the CPU 25, a work area, and the like, and includes storage elements such as a RAM and an EEPROM. The CPU 25 controls each unit according to a program stored in the memory 26.

  In addition, the printer controller 7 is a dot that indicates what size dot is formed on which position on the recording medium S based on the print data from the computer CP or whether a dot is not formed (non-recording). Formation data SI is generated, and the dot formation data SI is transmitted to the head controller 11. As will be described later, the printer 1 according to the present embodiment is configured to be capable of recording with four gradations including non-recording for one pixel, and the dot formation data SI is one of these gradations. This is a kind of pixel gradation data shown. Then, the head control unit 11 generates selection data for selecting each drive pulse included in the drive signal COM based on the dot formation data SI from the printer controller 7 and applying it to the piezoelectric vibrator 32. Accordingly, the printer controller 7 and the head controller 11 function as selection control means.

  Here, when the printer controller 7 generates the dot formation data SI, the first dot formation data SI1 (first gradation data) dedicated for the forward movement of the recording head 8 and the dedicated for the backward movement of the recording head 8 are used. And the second dot formation data SI2 (second gradation data). As will be described later, the printer 1 in the present embodiment employs a configuration in which only middle dots or large dots are recorded during forward movement, while only small dots are recorded during backward movement. , Middle dot, large dot, or non-recording data is referred to as first dot formation data SI1, and data indicating either small dot or non-recording is referred to as second dot formation data SI2. More specifically, the data corresponding to the dot formation data SI small dot is replaced with non-recording by the mask process to obtain the first dot formation data SI1. Similarly, the data corresponding to the middle dot or large dot in the dot formation data SI is replaced with non-recording to obtain second dot formation data SI1. Accordingly, during the forward movement, the first dot formation data SI1 is transmitted to the head controller 11, and the recording process by the recording head 8 is executed. During the forward movement, the second dot formation data SI2 is transmitted to the head controller 11. A recording process by the recording head 8 is executed.

  As shown in FIG. 2, the carriage 12 is attached in a state of being supported by a guide rod 19 installed in the main scanning direction, and the recording medium is moved along the guide rod 19 by the operation of the carriage moving mechanism 3. It is configured to reciprocate in the main scanning direction orthogonal to the S transport direction. The position of the carriage 12 in the main scanning direction is detected by the linear encoder 20, and a detection signal, that is, an encoder pulse (a kind of position information) is transmitted to the CPU 25 of the printer controller 7. The linear encoder 20 is a kind of position information output means, and outputs an encoder pulse corresponding to the scanning position of the recording head 8 as position information in the main scanning direction. Thereby, the printer controller 7 can control the recording operation by the recording head 8 while recognizing the scanning position of the carriage 12 (recording head 8) based on the encoder pulse EP from the linear encoder 20. The printer 1 is bi-directional between when the carriage 12 moves from the home position toward the opposite end (full position) and when the carriage 12 returns from the full position to the home position. Thus, a so-called bidirectional recording process for recording characters, images and the like on the recording paper S is performed.

  The encoder pulse EP from the linear encoder 20 is input to the printer controller 7. The printer controller 7 generates a timing pulse PTS (Print Timing Signal) from the encoder pulse EP, and performs transfer of print data, generation of a drive signal COM, and the like in synchronization with the timing pulse PTS. Then, the drive signal generation circuit 4 outputs the drive signal COM at a timing based on the timing pulse PTS. Further, the printer controller 7 generates a timing signal such as a latch signal LAT based on the timing pulse PTS and outputs the timing signal to the recording head 8. The latch signal LAT is a signal that defines the start timing of the recording cycle. Therefore, it can be said that the unit period of the drive signal COM is a section divided by the latch signal LAT.

Next, the configuration of the recording head 8 will be described with reference to FIG.
The recording head 8 includes a case 28, a vibrator unit 29 housed in the case 28, a flow path unit 30 joined to the bottom surface (tip surface) of the case 28, and the like. The case 28 is made of, for example, an epoxy resin, and a housing empty portion 31 for housing the vibrator unit 29 is formed therein. The vibrator unit 29 supplies a piezoelectric vibrator 32 (piezo element) functioning as a kind of pressure generating means, a fixing plate 33 to which the piezoelectric vibrator 32 is joined, and a drive signal to the piezoelectric vibrator 32. The flexible cable 34 is provided. The piezoelectric vibrator 32 is a laminated type produced by cutting a piezoelectric plate in which piezoelectric layers and electrode layers are alternately laminated into a comb-like shape, and can be expanded and contracted in a direction perpendicular to the laminating direction (electric field direction). This is a piezoelectric vibrator in a longitudinal vibration mode (field transverse effect type).

  The flow path unit 30 is configured by joining a nozzle plate 37 to one surface of the flow path substrate 36 and a diaphragm 38 to the other surface of the flow path substrate 36. The flow path unit 30 is provided with a reservoir 39 (also referred to as a common liquid chamber or a manifold), an ink supply port 40, a pressure chamber 41, a nozzle communication port 42, and a nozzle 43. A series of ink flow paths from the ink supply port 40 to the nozzle 43 through the pressure chamber 41 and the nozzle communication port 42 are formed corresponding to each nozzle 43. The nozzle plate 37 has a plurality of (for example, 180) nozzles 43 arranged in a line along the sub-scanning direction at a pitch (for example, 180 dpi) corresponding to the dot formation density, thereby forming a nozzle array (a kind of nozzle group). In this embodiment, for example, the member is made of stainless steel. The nozzle plate 37 may be made of a silicon single crystal substrate.

  The diaphragm 38 has a double structure in which an elastic film 46 is laminated on the surface of the support plate 45. In the present embodiment, the vibration plate 38 is manufactured using a composite plate material in which a stainless plate, which is a kind of metal plate, is used as the support plate 45 and a resin film is laminated on the surface of the support plate 45 as an elastic film 46. The diaphragm 38 is provided with a diaphragm portion 47 that changes the volume of the pressure chamber 41. In addition, the diaphragm 38 is provided with a compliance portion 48 that seals a part of the reservoir 39.

  The diaphragm portion 47 is manufactured by partially removing the support plate 45 by etching or the like. That is, the diaphragm portion 47 includes an island portion 49 to which the tip end surface of the free end portion of the piezoelectric vibrator 32 is joined, and a thin elastic portion 50 surrounding the island portion 49. The compliance portion 48 is produced by removing the support plate 45 in the region facing the opening surface of the reservoir 39 by etching processing or the like in the same manner as the diaphragm portion 47, and reduces the pressure fluctuation of the liquid stored in the reservoir 39. Functions as a damper to absorb.

  Since the tip surface of the piezoelectric vibrator 32 is joined to the island portion 49, the volume of the pressure chamber 41 can be changed by extending and contracting the free end portion of the piezoelectric vibrator 32. A pressure fluctuation occurs in the ink in the pressure chamber 41 along with the volume fluctuation. The recording head 8 ejects ink droplets from the nozzles 43 using this pressure fluctuation.

  FIG. 4 is a waveform diagram for explaining the configuration of the drive signal generated by the drive signal generation circuit 4 in the present embodiment, and a table showing the correspondence between each gradation (dot size) and selection of the drive pulse. Here, the unit period T, which is a repetition period of the drive signal, corresponds to the width of the pixel when the nozzle 43 ejects ink while the recording head 8 moves relative to the recording medium S. It corresponds to the time to move by distance. In the present embodiment, two types of dots can be formed for one pixel during forward movement, and one type of dot can be formed during backward movement. Accordingly, the printer 1 can express a total of four tones including non-recording in which dots are not formed for pixels. Specifically, a small dot with the smallest amount of ejected ink, a large dot with the largest amount of ejected ink, and a middle dot between the small dot and the large dot are formed. It is possible to do. Among these, a large dot is formed by sequentially selecting two ejection drive pulses DPM1 and DPM2 within the same unit period, applying them to the piezoelectric vibrator 32, and ejecting ink from the nozzle 43 in two steps. Dot. Large (large), medium (middle), and small (small), which indicate the size of the dot and the amount of ink droplets, are relative, and the size indicated by each depends on the printer specifications and recording mode. It will change accordingly. Further, the number of gradations is not limited to that exemplified, and the present invention can be applied to a configuration having a larger number of gradations or a smaller number of gradations.

  In the drive signal COM in the present embodiment, the unit cycle T is divided into three periods, specifically, a period T1, a period T2, and a period T3. Then, the first middle dot drive pulse DPM1 is generated in the period T1, the small dot drive pulse DPS is generated in the period T2, and the second middle dot drive pulse DPM2 is generated in the period T3. Among these ejection drive pulses, the first middle dot drive pulse DPM1 and the second middle dot drive pulse DPM2 are ejection drive pulses (a kind of first drive voltage in the present invention) used only during forward movement, The small dot drive pulse DPS is an ejection drive pulse (a kind of second drive voltage in the present invention) that is used only during the backward movement.

  The first middle dot drive pulse DPM1 alone is used to form middle dots. The combination of the first middle dot drive pulse DPM1 and the second middle dot drive pulse DPM2 is used when forming a large dot. The small dot drive pulse DPS is used when forming a small dot. In addition, since the structure and effect | action of the waveform of each injection drive pulse are known, detailed description is abbreviate | omitted.

  “◯” and “x” in the table in the lower part of FIG. 4 indicate whether or not to select a drive pulse for each period of the corresponding drive signal. That is, “X” indicates that the corresponding drive pulse is not selected (that is, not applied to the piezoelectric vibrator 32), and “◯” indicates that the corresponding drive pulse is selected (that is, applied to the piezoelectric vibrator 32). Show). When the dot formation data SI indicates “non-recording in which no dot is formed on the pixel” in a predetermined cycle, the selection of all the drive pulses is “x”. In this case, in this cycle, the drive pulse of the drive signal COM Neither is applied to the piezoelectric vibrator 32.

  When the dot formation data SI (first dot formation data SI1) in a predetermined cycle indicates “large dot”, the first middle dot drive pulse DPM1 in the period T1 and the second middle dot drive pulse DPM2 in the period T3 are selected. Applied to the piezoelectric vibrator 32. As a result, ink droplets corresponding to the middle dots are ejected twice continuously from the corresponding nozzles 43, and these ink droplets land on the pixel area on the recording medium S to form large dots. . Further, when the dot formation data SI (first dot formation data SI1) in a predetermined cycle indicates “middle dot”, the first middle dot drive pulse DPM1 in the period T1 is selected and applied to the piezoelectric vibrator 32. As a result, an ink droplet of an amount corresponding to the middle dot is ejected from the corresponding nozzle 43, and a middle dot is formed in the pixel area on the recording medium S. When the dot formation data SI (second dot formation data SI2) in the predetermined cycle indicates “small mold”, the small dot drive pulse DPS of the period T2 is selected and applied to the piezoelectric vibrator 32. As a result, an ink droplet of an amount corresponding to the small dot is ejected from the corresponding nozzle 43, and a small dot is formed in the pixel region on the recording medium S.

As described above, in the printer 1 according to the present embodiment, the recording process is performed only by the middle dot driving pulses DPM1 and DPM2 that are the first driving voltage during the forward movement, and the small dot driving that is the second driving voltage during the backward movement. Since the recording process is performed only by the pulse DPS, the ejection characteristics (nozzle when ejecting ink using the second drive voltage) due to the influence of residual vibration when the ink is ejected using the first drive voltage. The amount of ink ejected from 43 or the flying speed does not fluctuate. Similarly, the residual vibration when ink is ejected using the first drive voltage does not affect the ejection characteristics when ink is ejected using the second drive voltage. Thus, since it is not necessary to consider the influence of residual vibration between the first drive voltage and the second drive voltage, the first drive voltage is related to the arrangement (generation timing) of each ejection drive voltage in the drive signal COM. And the second drive voltage can be narrowed. As a result, the entire length of the drive signal COM, that is, the unit period T can be shortened. As a result, it is possible to drive at a higher frequency, and it is possible to achieve high resolution (higher density of dots) of the recorded image.
In addition, when the ink is ejected using each ejection drive voltage, the occurrence timing of either the first drive voltage or the second drive voltage is adjusted with respect to the landing position deviation of the reciprocating dot due to the difference in the flying speed of the ink. By doing so, it is possible to align the landing positions. Even in this case, since the timing can be adjusted without considering the influence of the residual vibration, it is possible to contribute to shortening the overall length of the drive signal COM without unnecessarily widening the waveform interval.
The drive signal COM may be configured to include a fine vibration pulse that finely vibrates the meniscus in the nozzle 43 to the extent that ink is not ejected during non-printing when ink is not ejected. In this case, the micro-vibration pulse may be used in common during forward movement and backward movement.

  Next, a description will be given of a recording process in which a predetermined region of the recording medium S such as a translucent resin sheet is painted with white ink (covers without a gap) in the printer 1. Here, the white ink is an ink containing a white pigment. For example, titanium dioxide can be suitably used as the white pigment.

  When the power is turned on, the printer controller 7 executes a predetermined initialization operation. In this initialization operation, the carriage 12 is moved in the main scanning direction to recognize the position of the carriage 12 (recording head 8), and unnecessary information in the work area of the memory 26 is cleared. When the initialization operation is performed, the printer controller 7 controls the carriage moving mechanism 3 and the transport mechanism 2 to move the carriage 12 in the main scanning direction and send the recording medium S in the sub-scanning direction (transport direction). Further, the printer controller 7 and the head controller 11 synchronize with the movement of the carriage 12 and the recording medium S, and at the time of forward movement, the piezoelectric vibrator 32 of the middle dot drive pulses DPM1, DPM2 based on the first dot formation data SI1. On the other hand, during the backward movement, the application of the small dot drive pulse DPS to the piezoelectric vibrator 32 is controlled based on the second dot formation data SI2.

  In the recording process of filling a predetermined area of the recording medium S, if a large amount of ink is landed at once, the ink oozes or oozes, or cockling that causes wrinkles due to the recording medium S sucking moisture rapidly. There is a risk. At the time of forward movement, most of the area to be filled is covered with white ink by large dots or middle dots, and at the time of backward movement, the remaining area of the area to be filled by small dot (part where dots are not formed) Is coated with white ink. By doing in this way, compared with the case where a predetermined area is painted at a time, problems such as ink seepage can be suppressed, and the present invention is suitable in such a case. Of course, the present invention is not limited to the illustrated fill, and recording with higher resolution can be performed at a higher drive frequency even when recording processing for other images and texts is performed.

  In addition, this invention is not limited to each above-mentioned embodiment, A various deformation | transformation is possible based on description of a claim.

For example, regarding the drive signal, in the above-described embodiment, the example illustrated in FIG. 4 has been described as an example of the drive signal COM in the present invention, but is not limited thereto.
FIG. 5 is a waveform diagram illustrating the configuration of the drive signals COM (COM1, COM2) in another embodiment of the present invention. In addition, the same code | symbol as the corresponding drive pulse is attached | subjected with respect to the drive pulse of the same waveform as each drive pulse in the said 1st Embodiment.
In the present embodiment, the drive signal generation circuit 4 includes a first drive signal COM1 dedicated to the forward movement including the middle dot drive pulses DPM1 and DPM2, and a second drive signal COM2 dedicated to the reverse movement including the small dot drive pulse DPS. And is different from the first embodiment. In the present embodiment, two systems of drive signals COM1 and COM2 are generated and switched between forward movement and backward movement. As a result, the entire length of the drive signal COM, that is, the unit period T can be further shortened as compared with the first embodiment in which all the drive pulses are included in one drive signal COM. As a result, it can be driven at a higher frequency, and the resolution of the recorded image can be further increased. In addition, since the number of dots formed per pass, which is the scanning unit of the recording head 8, can be increased, the recording process can be speeded up.

  Furthermore, in the present embodiment, the first drive signal COM1 and the second drive signal COM2 differ with respect to the reference potential that is a reference for the potential change of the ejection drive voltage due to the design and specification. Specifically, the reference potential Vb2 of the second drive signal COM2 is higher than the reference potential Vb1 of the first drive signal COM1. Here, for example, in the conventional configuration in which the first driving signal COM1 and the second driving signal COM2 are switched both in a reciprocating manner and the recording process is performed using each of the driving pulses DPM1, DPM2, and DPS, the reference of both driving signals is used. When the potentials are different from each other, a waveform component that connects the two reference potentials is necessary, which causes a problem that the length of the entire drive signal becomes longer. On the other hand, according to the configuration of the present embodiment, even when the reference potential is different, there is no switching of the drive signal at the time of forward movement or backward movement, so the above problem does not occur. For this reason, the design freedom of a drive signal and an injection drive voltage improves. Further, since switching of the drive signal does not occur during scanning during forward movement or backward movement, it is not necessary to consider the time required for switching (switching loss) when designing the drive signal. This also contributes to shortening the length of the drive signal. Since other configurations are the same as those in the first embodiment, description thereof will be omitted.

  In addition, the waveform and the number of ejection drive pulses (ejection drive voltage) included in the drive signal are not limited to those exemplified in the above embodiments. In short, the first drive voltage for the forward movement and the second drive voltage for the backward movement are included in the drive signal, and the first drive voltage and the second drive voltage are the ink ejected from the nozzle 43. As long as the waveforms are different from each other, various modes can be adopted. Therefore, the first drive voltage and the second drive voltage may be included in a single drive signal, or may be included in different drive signals.

In the above embodiment, the so-called longitudinal vibration type piezoelectric vibrator 32 is exemplified as the pressure generating means. However, the present invention is not limited to this, and for example, a so-called flexural vibration type piezoelectric element can be employed. In this case, with respect to the ejection driving pulse exemplified in the above embodiment, the waveform changes in the direction of potential change, that is, upside down.
Furthermore, the pressure generating means is not limited to the piezoelectric element, and when various pressure generating means such as a heat generating element that generates bubbles in the pressure chamber or an electrostatic actuator that changes the volume of the pressure chamber using electrostatic force is used. The present invention can also be applied.

In the above description, the ink jet printer 1 which is a kind of liquid ejecting apparatus has been described as an example, but the present invention is also applicable to a liquid ejecting apparatus that ejects liquid using a plurality of ejection driving pulses. Can do. For example, display manufacturing equipment for manufacturing color filters such as liquid crystal displays, organic EL (Electro
Applied to electrode manufacturing equipment for forming electrodes such as Luminescence displays and FEDs (surface emitting displays), chip manufacturing equipment for producing biochips (biochemical elements), and micropipettes for supplying very small amounts of sample solutions. can do.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Conveyance mechanism, 3 ... Carriage moving mechanism, 4 ... Drive signal generation circuit, 7 ... Printer controller, 8 ... Recording head, 11 ... Head control part, 12 ... Carriage, 32 ... Piezoelectric vibrator, 41 ... Pressure chamber, 43 ... Nozzle, S ... Recording medium

Claims (2)

A liquid ejecting head for ejecting liquid from the nozzle by driving the pressure generating means;
Drive signal generation means for generating a drive signal including an injection drive voltage for driving the pressure generation means,
A liquid ejecting apparatus that relatively moves the liquid ejecting head with respect to a liquid landing target, and that ejects liquid onto the liquid landing target during both forward movement and backward movement,
The drive signal generation means includes a first drive signal used at the time of forward movement, and a second drive signal used at the time of backward movement in which the size of the liquid ejected from the nozzle is different from the first drive signal. A liquid ejecting apparatus.   The first drive signal has a first drive voltage, the second drive signal has a second drive voltage different from the first drive voltage, and a reference potential serving as a reference for potential change of the drive voltage is the first drive voltage. The liquid ejecting apparatus according to claim 1, wherein the driving signal is different from the second driving signal.

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