JP2004074478A - Liquid ejecting apparatus and driving method of the same - Google Patents

Abstract

An object of the present invention is to minimize variations in ink drop weight and ink drop speed between a plurality of nozzle openings.
A discharge pulse applied to a pressure generating element includes a filling waveform element Pwc1 for expanding the volume of the pressure chamber to fill the pressure chamber with liquid, and an expansion holding waveform element Pwh1 for maintaining the expansion state of the pressure chamber. And a discharge waveform element Pnd for contracting the pressure chamber to discharge droplets from the nozzle openings. The time interval between the filling waveform element Pwc1 and the time interval between the expansion holding waveform element Pwh1 so that the start point of the discharge waveform element Pnd coincides with the point at which the meniscus vibrating due to the expansion of the pressure chamber is drawn most in the direction of the pressure chamber. Is set to be longer than the natural vibration period Tc of the pressure chamber.
[Selection diagram] Fig. 4

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, by applying a discharge pulse to a plurality of pressure generating elements provided corresponding to a plurality of pressure chambers communicating with a plurality of nozzle openings, a pressure fluctuation is caused in the liquid in the pressure chamber to cause a pressure change from the nozzle openings. The present invention relates to a liquid ejecting apparatus that ejects liquid droplets and a driving method of the liquid ejecting apparatus.
[0002]
[Prior art]
As a typical example of a conventional liquid ejecting apparatus, there is an ink jet recording apparatus provided with an ink jet recording head for image recording. Other liquid ejecting apparatuses include, for example, an apparatus provided with a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material (conductive paste) used for forming an electrode such as an organic EL display and an FED (surface emitting display). Examples of the apparatus include an apparatus equipped with an ejection head, an apparatus equipped with a biological organic substance ejection head used for biochip production, and an apparatus equipped with a sample ejection head as a precision pipette.
[0003]
The ink jet recording apparatus includes a recording head (liquid ejecting head) having a plurality of nozzle rows formed by arranging a large number of nozzle openings in a row, a carriage mechanism for moving the recording head in a main scanning direction (a recording paper width direction). And a paper feed mechanism for moving the recording paper in a sub-scanning direction (paper feeding direction) orthogonal to the main scanning direction.
[0004]
The recording head includes a plurality of pressure chambers communicating with the plurality of nozzle openings, and pressure generating elements for changing the ink pressure in each pressure chamber. In this recording head, an ink pulse in a pressure chamber is changed by supplying an ejection pulse to a pressure generating element, and an ink droplet is ejected from a nozzle opening.
[0005]
While moving in the main scanning direction, the recording head ejects ink droplets at a timing specified by the dot pattern data. Then, when the recording head reaches the end of the movement range, the paper feeding mechanism moves the recording paper in the sub-scanning direction. After the recording paper is moved, the carriage mechanism moves the recording head again in the main scanning direction, and the recording head ejects ink droplets during the movement.
[0006]
By repeating the above operation, an image based on the dot pattern data is recorded on the recording paper.
[0007]
This type of ink jet recording apparatus forms an image based on whether or not to eject ink droplets, that is, the presence or absence of dots. For this reason, a method of expressing an intermediate gradation by expressing one pixel with a plurality of dots such as 4 × 4, 8 × 8, or the like is adopted. In order to print a high-quality image by this method, it is necessary to eject a very small volume of ink droplets from the print head.
[0008]
In view of such circumstances, in order to satisfy conflicting demands for improvement in image quality and improvement in recording speed, a technique for ejecting ink droplets of different sizes from the same nozzle has been developed. For example, by supplying a plurality of pulse signals capable of generating minute ink droplets, a plurality of minute ink droplets are ejected from the same nozzle, and the respective ink droplets are united before landing on recording paper to form a large ink droplet. Generate.
[0009]
However, in this technique, the number of ink droplets that can be combined is limited, so that the size of the ink droplet is limited, and the variable range of the size is narrow. Further, control is difficult because a plurality of ink droplets must be united before landing.
[0010]
Therefore, a drive signal in which a plurality of types of ejection pulses corresponding to the volume of the ink droplet to be ejected are connected in series is generated, and an ejection pulse obtained by selecting a part of the drive signal is supplied to the pressure generating element. Technology is being developed.
[0011]
FIG. 5 shows a representative example of an ejection pulse applied to the pressure generating element when an ink droplet is ejected from the nozzle opening of the recording head. The discharge pulse is generated by filling the pressure chamber with ink by filling the pressure chamber by expanding the volume of the pressure chamber, an expansion holding waveform element Pwh1 holding the expansion state of the pressure chamber, and a nozzle opening by contracting the pressure chamber. An ejection waveform element Pnd for ejecting ink droplets, a contraction holding waveform element Pwh2 for holding the contracted state of the pressure chamber, and a vibration damping waveform element Pwc2 for damping the meniscus by expanding the contracted state of the pressure chamber. ing.
[0012]
FIG. 6 shows a vibration state of the meniscus caused by expanding the pressure chamber by applying the filling waveform element Pwc1 to the pressure generating element, wherein the horizontal axis represents the elapsed time t, and the vertical axis represents the position of the meniscus. Is shown. A curve A shown in FIG. 6 has a cycle corresponding to the natural oscillation cycle (Helmholtz oscillation cycle) Tc of the pressure chamber.
[0013]
When the elapsed time t on the horizontal axis in FIG. 6 is the total time T of the filling waveform element Pwc1 and the expansion holding waveform element Pwh1, the curve A indicating the vibration state of the meniscus is represented by the ink droplet ejected from the nozzle opening. (Iw) and the velocity (Vm) of the ink droplet. In other words, when the ejection waveform element Pnd starts at the time when the meniscus is most drawn in the direction of the pressure chamber, the weight of the ejected ink droplet is the lightest and the ejection speed is the slowest. Conversely, if the ejection waveform element Pnd starts when the meniscus is farthest from the pressure chamber, the heaviest and fastest ink droplet is ejected.
[0014]
In the conventional ink jet recording apparatus, the filling waveform element Pwc1 and the expansion holding waveform element Pwh1 are combined with each other in order to start the ejection waveform element Pnd at the point X of the valley of the curve A shown in FIG. Is set to the Helmholtz oscillation cycle Tc of the pressure chamber.
[0015]
The reason for this setting is as follows. Ideally, it is desirable that all of the plurality of pressure chambers formed in the recording head have a common natural oscillation period (Helmholtz oscillation period) Tc. Therefore, the Helmholtz oscillation period Tc varies even between the pressure chambers belonging to the same row. For this reason, the average value of the Helmholtz oscillation periods Tc of the plurality of pressure chambers is used as the Helmholtz oscillation period Tc used when setting the total time T of the filling waveform element Pwc1 and the expansion holding waveform element Pwh1 described above. ing. That is, the curve A shown in FIG. 6 shows the vibration state of the meniscus in the pressure chamber having the average Helmholtz oscillation period Tc.
[0016]
Next, FIG. 7 shows a curve B and a curve C in addition to the above-described curve A. The curve B shows the case of a pressure chamber having the maximum Helmholtz oscillation period Tc, and the curve C shows the minimum Helmholtz oscillation. The case of a pressure chamber having a period Tc is shown. As can be seen from FIG. 7, by adjusting the total time T of the filling waveform element Pwc1 and the expansion holding waveform element Pwh1 to the valley X of the curve A, the deviation amount ΔIa of the values of the curves B and C with respect to the value of the curve A is reduced. Can be minimized. That is, it is possible to minimize the variation in the ink droplet weight (Iw) and the variation in the ink droplet speed (Vm) due to the variation in the natural vibration period Tc among the plurality of pressure chambers.
[0017]
[Problems to be solved by the invention]
However, when the total time T (= Pwc1 + Pwh1) of the filling waveform element Pwc1 and the expansion holding waveform element Pwh1 is adjusted to Tc (average value) as described above, the end point of the total time T (that is, the starting point of the discharge waveform element Pnd) In fact, the inventor of the present invention has found that the point ()) does not correspond to the point X of the valley of the curve A shown in FIG. 7 but to the point X ′ slightly before the point X. This is probably because the waveform of the ejection pulse is not a so-called impulse waveform as shown in FIG. 5, but a ramp waveform in which a certain gradient is given to the filling waveform element Pwc1.
[0018]
As described above, when the total time T (= Pwc1 + Pwh1) does not correspond to the time X of the valley but to the time X ′ just before the time, the deviation ΔIb of the curves B and C with respect to the curve A increases as shown in FIG. Resulting in. That is, the variation in the ink droplet weight (Iw) and the variation in the ink droplet speed (Vm) between the plurality of nozzle openings become large.
[0019]
The present invention has been made in consideration of the above-described circumstances, and is directed to a liquid capable of minimizing a variation in ink droplet weight (Iw) and a variation in ink droplet speed (Vm) between a plurality of nozzle openings. An object of the present invention is to provide an injection device and a driving method of the same.
[0020]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a first aspect of the present invention is to apply a discharge pulse to a plurality of pressure generating elements provided in correspondence with a plurality of pressure chambers communicating with a plurality of nozzle openings, thereby forming the pressure chamber. Drive signal generating means for generating a drive signal for generating the discharge pulse applied to the plurality of pressure generating elements in a liquid ejecting apparatus which causes a pressure fluctuation in the liquid to discharge droplets from the nozzle openings And pulse generating means for generating the discharge pulse by selecting at least a part of the drive signal, wherein the discharge pulse expands a volume of the pressure chamber and fills the pressure chamber with a liquid. A filling waveform element, an expansion holding waveform element for holding the expanded state of the pressure chamber, and a discharge waveform element for discharging the droplet from the nozzle opening by contracting the pressure chamber. The time interval of the filling waveform element and the expansion holding waveform are adjusted so that the meniscus vibrating due to the expansion of the pressure chamber is most drawn in the direction of the pressure chamber and the start point of the discharge waveform element is adjusted. The total time of the element and the time interval is set to be longer than the natural oscillation period (Tc) of the pressure chamber.
[0021]
In order to solve the above-mentioned problem, a second aspect of the present invention is to apply a discharge pulse to a plurality of pressure generating elements provided corresponding to a plurality of pressure chambers communicating with a plurality of nozzle openings, thereby to provide the pressure chamber. A driving method for generating a driving signal for generating the discharge pulse applied to the plurality of pressure generating elements, in a method of driving a liquid ejecting apparatus that causes pressure fluctuation in the liquid to discharge liquid droplets from the nozzle openings. A signal generation step, and a pulse generation step of generating the discharge pulse by selecting at least a part of the drive signal, wherein the discharge pulse expands the volume of the pressure chamber and enters the pressure chamber. A filling waveform element for filling a liquid, an expansion holding waveform element for maintaining an expanded state of the pressure chamber, and a discharge waveform for discharging the droplet from a nozzle opening by contracting the pressure chamber. Element, and the time interval of the filling waveform element so that the meniscus vibrating due to the expansion of the pressure chamber is aligned with the start point of the discharge waveform element at the time of being drawn most in the direction of the pressure chamber. The total time of the expansion holding waveform element and the time interval is set to be longer than the natural oscillation period (Tc) of the pressure chamber.
[0022]
In the first and second aspects of the present invention, preferably, the total time of the time interval of the filling waveform element and the time interval of the expansion holding waveform element is 2 microseconds in the natural oscillation period (Tc) of the pressure chamber. This value is obtained by adding the following time.
[0023]
Preferably, a total time of the time interval of the filling waveform element and the time interval of the expansion holding waveform element is 130% or less of the natural oscillation period (Tc) of the pressure chamber.
[0024]
Preferably, the total time of the time interval of the filling waveform element and the time interval of the expansion holding waveform element is equal to the natural oscillation cycle (Tc) of the pressure chamber and the natural oscillation cycle (Tc) of the pressure chamber. This is a value obtained by adding a time of 1/8 or less.
[0025]
Preferably, the plurality of pressure chambers have a variation in their natural oscillation period (Tc), and in a pressure chamber having a natural oscillation period (Tc) halfway between the longest period and the shortest period, the expansion of the pressure chambers The time at which the meniscus vibrating due to the above is drawn most in the direction of the pressure chamber coincides with the start point of the discharge waveform element.
[0026]
Preferably, the plurality of pressure chambers have a variation in their natural vibration period (Tc), and vibrate due to expansion of the pressure chamber in a pressure chamber having an average natural vibration period (Tc). The point at which the meniscus is drawn most in the direction of the pressure chamber coincides with the start point of the discharge waveform element.
[0027]
Preferably, the pressure generating element is constituted by a piezoelectric vibrator in a longitudinal vibration mode or a flexural vibration mode.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an ink jet recording apparatus as one embodiment of a liquid ejecting apparatus according to the present invention and a driving method of the apparatus will be described with reference to the drawings.
[0029]
FIG. 1 is a perspective view showing a schematic configuration of the ink jet recording apparatus according to the present embodiment. In FIG. 1, reference numeral 1 denotes a carriage. The carriage 1 is guided by a guide member 4 via a timing belt 3 driven by a carriage motor 2, and is reciprocated in the axial direction of a platen 5. I have. The carriage 1, the carriage motor 2, the timing belt 3, and the guide member 4 constitute a carriage mechanism that causes the inkjet recording head 12 to scan in the main scanning direction together with the carriage 1.
[0030]
The ink jet recording head 12 is mounted on the side of the carriage 1 facing the recording paper 6, and an ink cartridge 7 for supplying ink to the recording head 12 is detachably mounted on the upper part thereof.
[0031]
A cap member 13 is disposed at a home position (right side in FIG. 1) which is a non-printing area of the ink jet recording apparatus. The cap member 13 moves the recording head 12 mounted on the carriage 1 to the home position. Sometimes, the recording head 12 is configured to be pressed against the nozzle forming surface to form a closed space between the recording head 12 and the nozzle forming surface. A pump unit 10 for applying a negative pressure to a closed space formed by the cap member 13 is disposed below the cap member 13.
[0032]
In the vicinity of the printing area side of the cap member 13, a wiping unit 11 having an elastic plate such as rubber is disposed so as to be able to advance and retreat in a horizontal direction with respect to the movement locus of the recording head 12, for example. When reciprocating to the member 13 side, the nozzle forming surface of the recording head 12 can be wiped as necessary.
[0033]
The ink jet recording apparatus further includes a feed mechanism for intermittently conveying the recording paper 6 on which recording is performed by the recording head 12 in a sub-scanning direction orthogonal to the main scanning direction.
[0034]
FIG. 2 is a functional block diagram of the ink jet recording apparatus according to the present embodiment. As shown in FIG. 2, the recording apparatus includes a printer controller 61 and a print engine 62. The printer controller 61 includes an interface 63 for receiving print data and the like from a host computer (not shown), a RAM 64 for storing various data, a ROM 65 for storing control routines for various data processing, and a CPU. , An oscillation circuit 66, a drive signal generation circuit (drive signal generation means) 83 for generating a drive signal, and print data and drive signals developed in dot pattern data (bitmap data). And an interface 67 for transmitting the print data to the print engine 62.
[0035]
In addition, the printer controller 61 detachably holds a memory card 76, which is a type of recording medium, and sends a card slot 77 functioning as a recording medium holding unit and information recorded on the memory card 76 to the control unit 82. And a card interface 78 for transmission. In the memory card 76, data on the waveform of the drive signal is recorded. As a recording medium other than the memory card 76, for example, a floppy disk, a hard disk, a magneto-optical disk, or the like can be used.
[0036]
The control unit 82 is a type of computer, and controls the ejection of ink droplets with reference to the waveform data of the drive signal recorded on the memory card 76, the control routine recorded on the ROM 65, and the like.
[0037]
The interface 63 receives, for example, any one of character code, graphic function, and image data or print data including a plurality of data from the host computer. Further, the interface 63 can output a busy (BUSY) signal, an acknowledge (ACK) signal, and the like to the host computer.
[0038]
The RAM 64 is used as a reception buffer, an intermediate buffer, an output buffer, a work memory (not shown), and the like. Print data from the host computer is temporarily stored in the reception buffer, intermediate code data is stored in the intermediate buffer, and dot pattern data is developed in the output buffer.
[0039]
The ROM 65 stores various control routines executed by the control unit 82, font data, graphic functions, and the like.
[0040]
Note that the ROM 65 stores a control routine (control program) that is continuously used without being changed. Data that is scheduled to be upgraded or changed, such as data related to the waveform of the drive signal, is recorded in the memory card 76.
[0041]
Further, the control unit 82 controls the drive signal generation circuit 83 based on the data on the waveform of the drive signal read from the memory card 76 to generate a predetermined drive signal according to the print mode.
[0042]
The print engine 62 includes a stepping motor 80 for driving the recording head 12 in the main scanning direction, a paper feed motor 81 for transporting recording paper, and an electric drive system 71 for the recording head 12. The electric drive system 71 of the recording head 12 includes a shift register 72, a latch circuit 73, a level shifter 74, a switch 75, a piezoelectric vibrator 161 and the like. Note that the shift register 72, the latch circuit 73, the level shifter 74, and the switch 75 function as pulse generation means.
[0043]
As the control unit 82, for example, a host computer directly connected to the recording apparatus by itself or one of a large number of computers connected via a network can be used.
[0044]
FIG. 3 is a sectional view showing the structure of the recording head of the ink jet recording apparatus shown in FIG.
[0045]
The recording head 12 includes a base 163 made of a synthetic resin, and a flow path unit 164 attached to a front surface (corresponding to the left side in the figure) of the base 163. The flow path unit 164 includes a nozzle plate 166 having a nozzle opening 165 formed therein, a vibration plate 167, a flow path forming plate 168, and a sheet 176.
[0046]
The base 163 is a block-shaped member provided with an accommodation space 169 that is open at the front and back. The piezoelectric vibrator 161 fixed to the fixed substrate 170 is accommodated in the accommodation space 169.
[0047]
The nozzle plate 166 is a thin plate-like member having a large number of nozzle openings 165 formed in the sub-scanning direction. Each nozzle opening 165 is opened at a predetermined pitch corresponding to the dot formation density. The vibration plate 167 and the sheet 176 form an island portion 171 as a thick portion with which the piezoelectric vibrator 161 contacts, and a thin portion 172 provided to surround the island portion 171 and having elasticity. .
[0048]
A large number of island portions 171 are provided at a predetermined pitch such that one island portion 171 corresponds to one nozzle opening 165.
[0049]
The flow path forming plate 168 is provided with an opening for forming a pressure chamber 173, a common ink chamber 174, and an ink supply port 175 that connects the pressure chamber 173 and the common ink chamber 174.
[0050]
Then, the nozzle plate 166 is disposed on the front surface of the flow path forming plate 168, and the diaphragm 167 and the sheet 176 are disposed on the rear side, and the nozzle plate 166, the diaphragm 167 and the sheet 176 are used to form the flow path forming plate 168. The flow path unit 164 is formed integrally by bonding or the like while sandwiching the.
[0051]
In the flow channel unit 164, a pressure chamber 173 is formed on the back side of the nozzle opening 165, and the island portion 171 of the diaphragm 167 is located on the back side of the pressure chamber 173. Further, the pressure chamber 173 and the common ink chamber 174 communicate with each other through an ink supply port 175.
[0052]
The front end of the piezoelectric vibrator 161 is in contact with the island portion 171 from the back side, and the piezoelectric vibrator 161 is fixed to the base 163 in this contact state. In addition, a drive signal (COM), print data (SI), and the like are supplied to the piezoelectric vibrator 161 via a flexible cable.
[0053]
The piezoelectric vibrator 161 in the longitudinal vibration mode has a characteristic that when charged, contracts in a direction perpendicular to the electric field, and when discharged, expands in a direction perpendicular to the electric field. Therefore, in the recording head 12, when charged, the piezoelectric vibrator 161 contracts rearward, and with this contraction, the island portion 171 is pulled back backward, and the contracted pressure chamber 173 expands. With the expansion, the ink in the common ink chamber 174 flows into the pressure chamber 173 through the ink supply port 175. On the other hand, the discharge causes the piezoelectric vibrator 161 to extend forward, the island portion 171 of the elastic plate is pushed forward, and the pressure chamber 173 contracts. With the contraction, the ink pressure in the pressure chamber 173 increases.
[0054]
FIG. 4 shows an ejection pulse generated by selecting a part of the drive signal generated by the drive signal generation circuit 83.
[0055]
The ejection pulse expands the volume of the pressure chamber 173 and fills the pressure chamber 173 with ink, an expansion holding waveform element Pwh1 that maintains the expanded state of the pressure chamber 173, and contracts the pressure chamber 173. An ejection waveform element Pnd for ejecting ink droplets from the nozzle opening 165, a contraction holding waveform element Pwh2 for holding the contracted state of the pressure chamber 173, and a vibration control element for damping the meniscus by expanding the contracted pressure chamber 173. A vibration waveform element Pwc2.
[0056]
In the present embodiment, the end point of the expansion holding waveform element Pwh1, that is, the start point of the discharge waveform element Pnd is set to the time X at which the meniscus vibrating due to the expansion of the pressure chamber 173 is drawn most toward the pressure chamber 173. According to (see FIG. 6), the total time T of the time interval of the filling waveform element Pwc1 and the time interval of the expansion holding waveform element Pwh1 is set to Tc + α longer than the natural oscillation period Tc of the pressure chamber 173. .
[0057]
In comparison with the conventional discharge pulse shown in FIG. 5, the discharge pulse in the present embodiment shown in FIG. 4 is different from the conventional discharge pulse in that the time interval of the expansion holding waveform element Pwh1 in the conventional discharge pulse shown in FIG. Is also longer.
[0058]
This total time T (= Tc + α) is preferably a value obtained by adding a time of 2 microseconds or less to the natural vibration period Tc of the pressure chamber 173.
[0059]
Alternatively, the total time T (= Tc + α) is set to 130% or less of the natural vibration period Tc of the pressure chamber 173.
[0060]
Further, the total time T (= Tc + α) may be a value obtained by adding a time equal to or less than １ ／ times the natural vibration cycle Tc of the pressure chamber 173 to the natural vibration cycle Tc of the pressure chamber 173.
[0061]
If the natural vibration periods (Tc) of the plurality of pressure chambers 173 vary, the natural vibration period (Tc) or the average natural vibration period (Tc) which is intermediate between the longest period and the shortest period is determined. In the pressure chamber 173, the drive signal is generated such that the point at which the meniscus vibrating due to the expansion of the pressure chamber 173 due to the filling waveform element Pwc 1 is drawn most in the direction of the pressure chamber 173 coincides with the start point of the discharge waveform element Pnd. design.
[0062]
As described above, in the present embodiment, the starting point of the discharge waveform element Pnd is filled so that the meniscus vibrating due to the expansion of the pressure chamber 173 is set to the time X at which the meniscus vibrated most toward the pressure chamber 173. Since the total time T of the time interval of the waveform element Pwc1 and the time interval of the expansion holding waveform element Pwh1 is set to Tc + α longer than the natural oscillation period Tc of the pressure chamber 173, it has already been described with reference to FIG. As described above, it is possible to minimize the variation in the ink droplet weight (Iw) and the variation in the ink droplet speed (Vm) due to the variation in the natural oscillation period Tc among the plurality of pressure chambers 173, and to achieve a stable operation. Printing quality without unevenness can be provided.
[0063]
In the above embodiment, the recording head using the piezoelectric vibrator in the longitudinal vibration mode as the pressure generating element has been exemplified. However, the present invention can be applied to a recording head using the piezoelectric vibrator in the flexural vibration mode. . In the recording head using the piezoelectric vibrator in the flexural vibration mode, the relationship between the voltage level due to the charging and discharging of the piezoelectric vibrator and the expansion and contraction of the pressure chamber is determined by the recording head 12 using the piezoelectric vibrator in the vertical vibration mode. Is the reverse of the case. Therefore, when a recording head using a piezoelectric vibrator in the flexural vibration mode is used, the driving signal for the recording head 12 shown in FIG. Waveforms are used. That is, the filling of the pressure chamber with the ink is performed by lowering the voltage. Similarly, the ejection of ink droplets is performed by increasing the voltage.
[0064]
The same effects as those of the above-described embodiment can be obtained in an ink jet recording apparatus including a recording head using a piezoelectric vibrator in such a flexural vibration mode.
[0065]
【The invention's effect】
As described above, according to the present invention, the time interval of the filling waveform element is adjusted so that the start point of the discharge waveform element is adjusted to the point at which the meniscus vibrating due to the expansion of the pressure chamber is most retracted in the direction of the pressure chamber. Is set to be longer than the natural oscillation period of the pressure chamber, the weight of the ink droplet resulting from the variation of the natural oscillation period (Tc) among the plurality of pressure chambers. And variations in ink droplet speed can be minimized, and stable print quality without unevenness can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of an ink jet recording apparatus according to an embodiment of a liquid ejecting apparatus according to the present invention.
FIG. 2 is a functional block diagram of the ink jet recording apparatus shown in FIG.
FIG. 3 is a sectional view showing a structure of a recording head of the ink jet recording apparatus shown in FIG.
FIG. 4 is a diagram showing a waveform of an ejection pulse used in the ink jet recording apparatus shown in FIG.
FIG. 5 is a diagram showing a waveform of an ejection pulse used in a conventional ink jet recording apparatus.
FIG. 6 illustrates a vibration state of a meniscus caused by expanding a pressure chamber by applying a filling waveform element of a discharge pulse to a pressure generating element in a pressure chamber having an average natural oscillation period among a plurality of pressure chambers. Figure.
FIG. 7 expands the pressure chamber by applying a filling waveform element of a discharge pulse to the pressure generating element in each of the pressure chambers having an average natural oscillation cycle, a maximum natural oscillation cycle, and a minimum natural oscillation cycle. The figure which showed the vibration state of the meniscus caused by the.
[Explanation of symbols]
72 shift register 73 latch circuit 74 level shifter 75 switch 82 control unit 83 drive signal generation circuit (drive signal generation means)
12 Recording Head 161 Piezoelectric Vibrator 165 Nozzle Opening 166 Nozzle Plate 173 Pressure Chamber T Total Time Tc of Filling Waveform Element Pwc1 and Expansion Holding Waveform Element Pwh1 Natural Vibration Period (Period of Helmholtz Vibration) of Pressure Chamber
Pwc1 Fill waveform element Pwh1 Expansion hold waveform element Pnd Discharge waveform element Pwh2 Contraction hold waveform element Pwc2 Vibration suppression waveform element

Claims (13)

By applying a discharge pulse to a plurality of pressure generating elements provided corresponding to the plurality of pressure chambers communicating with the plurality of nozzle openings, a pressure change is generated in the liquid in the pressure chamber, and droplets are discharged from the nozzle openings. In a liquid ejecting apparatus that discharges
Drive signal generating means for generating a drive signal for generating the ejection pulse applied to the plurality of pressure generating elements,
Pulse generating means for generating the ejection pulse by selecting at least a part of the drive signal,
The discharge pulse is a filling waveform element that expands the volume of the pressure chamber and fills the pressure chamber with a liquid, an expansion holding waveform element that maintains the expansion state of the pressure chamber, and a nozzle that contracts the pressure chamber to form a nozzle. Discharge waveform element for discharging droplets from the opening,
The time interval between the filling waveform element and the expansion holding waveform element is adjusted so that the meniscus vibrating due to the expansion of the pressure chamber is aligned with the start point of the discharge waveform element at the time when the meniscus is most retracted in the direction of the pressure chamber. A liquid ejecting apparatus characterized in that a total time with a time interval is set longer than a natural oscillation period (Tc) of the pressure chamber. The total time of the time interval of the filling waveform element and the time interval of the expansion holding waveform element is a value obtained by adding a time of 2 microseconds or less to the natural oscillation period (Tc) of the pressure chamber. The liquid ejecting apparatus according to claim 1. The liquid ejection according to claim 1, wherein a total time of a time interval of the filling waveform element and a time interval of the expansion holding waveform element is 130% or less of a natural oscillation period (Tc) of the pressure chamber. apparatus. The total time of the time interval of the filling waveform element and the time interval of the expansion holding waveform element is equal to or less than 1/8 times the natural vibration cycle (Tc) of the pressure chamber, 2. The liquid ejecting apparatus according to claim 1, wherein the value is obtained by adding the time. The plurality of pressure chambers have a variation in their natural vibration period (Tc). In a pressure chamber having a natural vibration period (Tc) halfway between the longest period and the shortest period, vibration occurs due to expansion of the pressure chamber. 5. The liquid ejecting apparatus according to claim 1, wherein a point in time at which the meniscus is drawn most in the direction of the pressure chamber coincides with a start point of the ejection waveform element. 6. The plurality of pressure chambers have a variation in their natural vibration period (Tc). In a pressure chamber having an average natural vibration period (Tc), a meniscus vibrating due to the expansion of the pressure chamber is generated by the pressure chamber. 5. The liquid ejecting apparatus according to claim 1, wherein a point in time when the liquid crystal device is most drawn in the direction coincides with a start point of the ejection waveform element. 6. The liquid ejecting apparatus according to claim 1, wherein the pressure generating element is configured by a piezoelectric vibrator in a longitudinal vibration mode or a flexural vibration mode. By applying a discharge pulse to a plurality of pressure generating elements provided corresponding to the plurality of pressure chambers communicating with the plurality of nozzle openings, a pressure change is generated in the liquid in the pressure chamber, and droplets are discharged from the nozzle openings. In the driving method of the liquid ejecting apparatus for ejecting
A drive signal generating step of generating a drive signal for generating the ejection pulse applied to the plurality of pressure generating elements,
A pulse generating step of generating the ejection pulse by selecting at least a part of the driving signal,
The discharge pulse is a filling waveform element that expands the volume of the pressure chamber and fills the pressure chamber with a liquid, an expansion holding waveform element that maintains the expansion state of the pressure chamber, and a nozzle that contracts the pressure chamber to form a nozzle. Discharge waveform element for discharging droplets from the opening,
The time interval between the filling waveform element and the expansion holding waveform element is adjusted so that the meniscus vibrating due to the expansion of the pressure chamber is aligned with the start point of the discharge waveform element at the time when the meniscus is most retracted in the direction of the pressure chamber. A method for driving a liquid ejecting apparatus, wherein a total time with a time interval is set longer than a natural oscillation period (Tc) of the pressure chamber. The total time of the time interval of the filling waveform element and the time interval of the expansion holding waveform element is a value obtained by adding a time of 2 microseconds or less to the natural oscillation period (Tc) of the pressure chamber. A method for driving a liquid ejecting apparatus according to claim 8. 9. The liquid jet according to claim 8, wherein a total time of a time interval of the filling waveform element and a time interval of the expansion holding waveform element is 130% or less of a natural oscillation period (Tc) of the pressure chamber. How to drive the device. The total time of the time interval of the filling waveform element and the time interval of the expansion holding waveform element is equal to or less than １ ／ times the natural vibration cycle (Tc) of the pressure chamber, that is, the natural vibration cycle (Tc) of the pressure chamber. 9. The driving method for a liquid ejecting apparatus according to claim 8, wherein the value is obtained by adding the time. The plurality of pressure chambers have a variation in their natural vibration period (Tc). In a pressure chamber having a natural vibration period (Tc) halfway between the longest period and the shortest period, vibration occurs due to expansion of the pressure chamber. The method according to any one of claims 8 to 11, wherein a time point at which the meniscus is drawn in the direction of the pressure chamber coincides with a start point of the ejection waveform element. The plurality of pressure chambers have a variation in their natural vibration period (Tc). In a pressure chamber having an average natural vibration period (Tc), a meniscus vibrating due to the expansion of the pressure chamber is generated by the pressure chamber. The method according to any one of claims 8 to 11, wherein a point in which the ejection waveform element is most drawn in the direction of (1) coincides with a start point of the ejection waveform element.

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