JP4764038B2 - Driving method of ink jet recording apparatus - Google Patents

Description

  The present invention relates to an inkjet driving method employing multi-drop driving.

  A nozzle that communicates with an ink chamber containing ink, and an actuator that changes the volume of the ink chamber according to a drive waveform; and a plurality of ink droplets are generated from the nozzle by the operation of the actuator. There is known an ink jet driving method in which one pixel is formed by continuously discharging a single pixel. In this inkjet driving method, when the time for the pressure wave in the ink chamber to propagate from one end to the other end in the ink discharge direction is AL, it takes at least 3 AL to discharge one drop of ink. This is because it is composed of a total of 3 ALs of a pulse for performing the ink ejection operation in each multi-drop and a pulse for canceling the vibration of the ink after ink ejection.

  Ink jet heads that fly a plurality of droplets and form one pixel with the plurality of droplets are known (see, for example, Patent Document 1).

  Further, an ink jet recording apparatus is known in which clogging due to an ink film is prevented by operating a piezoelectric vibrator to swing a meniscus of a nozzle opening during non-printing (for example, Patent Document 2). reference).

  Further, an ink jet recording method is known that uses a second voltage pulse for ejecting ink droplets with respect to a first voltage pulse for retreating a meniscus before ink droplet formation in the reverse ejection direction (for example, Patent Document 3). reference).

Furthermore, there is known an ink jet printer that generates a drive signal including a pulse for vibrating a liquid surface at the tip of a nozzle without discharging a droplet from the nozzle to a pixel that does not discharge ink ( For example, see Patent Document 4).
Japanese Patent Laid-Open No. 7-117225 JP 7-137252 A JP-A-63-153149 Japanese Patent Laid-Open No. 10-250064

  As described above, since it takes a long time to discharge one drop, when the number of multidrops increases, it becomes extremely difficult to drive at high speed.

The present invention has been made in view of the above points, and an object of the present invention is to provide an ink jet recording apparatus capable of high-speed driving in an ink jet recording apparatus that forms one pixel by continuously ejecting ink droplets from a nozzle a plurality of times. It is to provide a driving method.

The invention described in claim 1 includes a nozzle that communicates with an ink chamber that contains ink and discharges ink in the ink chamber, and an actuator that changes the volume of the ink chamber according to a drive waveform. An ink jet recording apparatus that forms one pixel by continuously ejecting ink droplets from the nozzle a plurality of times by continuously applying a drive pulse to the actuator a plurality of times to expand the ink chamber and return the actuator to the original state . In the driving method, when the time during which the pressure wave in the ink chamber propagates from one end to the other end in the ink ejection direction is AL, the driving pulse whose time width for expanding the ink chamber is less than AL is set to 2.25 AL ~ 2.4 AL pulse period is continuously supplied to the actuator, and a plurality of inks are continuously ejected to form one pixel. The cancel pulse for suppressing the residual vibration of the ink chamber after the last drive pulse of the plurality of drive pulses forming one pixel is set as a time between the front end portion of the last drive pulse and the front end portion of the cancel pulse. The interval is set to Td, and the pulse width of the cancel pulse is set to 1.4 AL to 1.9 AL to supply the actuator to the actuator after the last drive pulse.

According to a second aspect of the present invention, there is provided a nozzle that communicates with an ink chamber that contains ink and ejects ink in the ink chamber, and an actuator that changes the volume of the ink chamber in accordance with a drive waveform. An ink jet recording apparatus that forms one pixel by continuously ejecting ink droplets from the nozzle a plurality of times by continuously applying a drive pulse to the actuator a plurality of times to expand the ink chamber and return the actuator to the original state . In the driving method, when the time during which the pressure wave in the ink chamber propagates from one end to the other end in the ink discharge direction is AL, the driving pulse whose time width for expanding the ink chamber is AL or less is 2.25 to 2.4. The actuator is continuously supplied to the actuator with a pulse period Td of AL, and before the first drive pulse of the plurality of drive pulses, ink is supplied. A pre-pulse that causes ink vibration to the extent that it is not ejected is applied to the actuator, and the time interval between the intermediate position between the front end and the rear end of the pre-pulse and the intermediate position between the front end and the rear end of the first drive pulse is set. The pulse width of the pre-pulse is 2.25 to 2.4 AL, which is equal to or less than the pulse width of the first drive pulse.

According to the first aspect of the present invention, it is possible to reliably suppress the residual vibration of the ink in the ink chamber. As a result, the head can be driven at a higher speed.

According to the second aspect of the present invention, the head can be driven at a high speed.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a schematic configuration of the Kaiser type inkjet head will be described with reference to FIG. FIG. 12A is a cross-sectional view along a plane including the partition wall of FIG.

  As shown in FIG. 12, the Kaiser-type inkjet head is configured by partitioning a plurality of ink chambers 11 that contain ink with partition walls 12. Each ink chamber 11 is provided with a nozzle 13 for ejecting ink droplets. The bottom surface of each ink chamber 11 is formed by a vibration plate 14, and a plurality of piezoelectric members 15 are fixed to the lower surface side of the vibration plate 14 corresponding to each ink chamber 11. The diaphragm 14 and the piezoelectric member 15 constitute an actuator, and the piezoelectric member 15 is electrically connected to the output terminal of the drive waveform generating means 16.

  In FIG. 12A, 16 is a common ink chamber, and 17 is an ink supply port.

  Next, a schematic configuration of the share-mode ink jet head will be described with reference to FIG. FIG. 13A is a cross-sectional view in a plane including the nozzle of FIG.

  As shown in FIG. 13, the partition wall 21 of the shear-mode type ink jet head is composed of a piezoelectric member that is distorted in the shear direction. A driving voltage output from the driving waveform generating means 22 is applied to the partition wall 21. Then, the piezoelectric member is deformed by application of the driving voltage, the volume in the ink chamber 23 is deformed, and ink is ejected from the nozzle 24.

  In FIG. 13A, 25 is a common ink chamber, and 26 is an ink supply port.

  Hereinafter, an inkjet driving method according to the present invention will be described using the share-mode inkjet head of FIG.

  First, the difference between the inkjet driving method of the present invention and the conventional inkjet driving method will be described.

  A so-called multi-drop driving method is known in which a plurality of droplets are continuously ejected from a nozzle 24 to form one pixel. For example, a driving method in which eight droplets are continuously ejected from the nozzle 24 to form one pixel will be described as an example.

  In the conventional multi-drop driving method, eight driving pulses P1 to P8 are applied to the partition wall 21 as shown in FIG.

  Each of the driving pulses P1 to P8 in the conventional driving method has an expansion pulse Pa for expanding the ink chamber 23 and a contracting pulse Pb for contracting the ink chamber 23 thereafter. One set of ink is ejected from the nozzle 24 by this set of expansion pulse Pa and contraction pulse Pb.

  On the other hand, in the driving method of the present invention, as shown in FIGS. 1B to 1D, only the expansion pulse Pa is used as the driving pulse, and the contraction pulse Pb is not used.

  In the present invention, when the time during which the pressure wave in the ink chamber 23 propagates from one end to the other end in the ink discharge direction is AL, a pulse having a time width AL or less is input in the direction in which the ink chamber 23 is expanded. Hereinafter, this pulse is referred to as a first drive pulse Px. This is because if the time width of the first drive pulse Px is longer than the AL time, the pressure in the ink chamber 23 is increased when the pressure in the ink chamber 23 is decreasing, so efficiency is not good.

  Then, in accordance with the vibration of the ink in the ink chamber 23 caused by the first first drive pulse Px, the next first drive pulse Px is applied to discharge the next ink. By repeating this operation, a plurality of droplets are continuously ejected to form one pixel.

That is, as shown in FIG. 1B, eight drive pulses P1 to P8 are applied continuously. In FIG. 1B, a cancel pulse is applied after the drive pulse P8. The operation in a state where the cancel pulse is not applied will be described below.

  If the cycle Td for applying the first drive pulse Px is set to an even multiple of AL, the efficiency is improved, but the pressure in the ink chamber 23 and the ink flow velocity increase every time ink is ejected, and immediately, defective printing and misdirection printing are performed. For example, stable ink ejection cannot be obtained (see FIG. 2). FIG. 2A shows a waveform in which the cycle Td of the first drive pulse Px is 2AL. FIG. 2B shows the pressure in the ink chamber 23 and the ink flow velocity when the drive pulse of FIG. 2A is applied. That is, as shown in FIG. 2B, the pressure in the ink chamber 23 and the ink flow velocity change, so that stable ink ejection cannot be obtained.

  Therefore, in the present invention, one pixel is formed by applying the first drive pulse Px to the inkjet head at a period Td that is 2.25 to 2.4 times, preferably 2.29 to 2.38 times AL, and continuously ejecting ink. I have to. The technical significance of 2.29 to 2.38 will be described later with reference to Table 1.

  In this way, by applying the first drive pulse Px to the inkjet head at a period Td shifted with respect to twice AL, an increase in the pressure in the ink chamber 23 and the ink flow velocity for each drop is suppressed, and each drop is reduced. Stable ink ejection is obtained (see FIG. 3).

  Here, AL = 2.4 μS. As shown in FIG. 3 (A), the pulse width Tw of the first drive pulse Px is set to 1.5 μS which is AL (= 2.4 μS) or less, and the cycle Td is 4.8 (= 2.4 × 2) which is twice AL. The shifted 5.7 μS. By doing so, as shown in FIG. 3B, an increase in the pressure of the ink chamber 23 and the ink flow velocity in each drop is suppressed, and stable ink ejection is performed in each drop.

  Next, the print quality was confirmed by experiment by changing the pulse width Tw and the period Td of the first drive pulse Px.

  Here, the used inkjet head is of the share-mode type shown in FIG. 13, and is driven by a three-division driving method in which the inkjet head is divided into three nozzle groups. The cycle quality of the eight first drive pulses Px was set to Tc (= 53.5 μS), and the print quality when printing was actually performed by changing the cycle Td and the pulse width Tw of the first drive pulse Px was examined. . Here, an ink having a viscosity of 10 cp and a surface tension of 30 N / m was used.

Table 1 shows the printing results at this time.

  As shown in Table 1, when the period Td of the first drive pulse Px is in the range of 5.5 to 5.7 and the pulse width Tw is AL (= 2.4 μS) or less, the print quality is “Good (Good)”. It turned out to be.

  5.5 / AL (= 2.4 μS) is 2.29, and 5.7 / AL (= 2.4 μS) is 2.38. In consideration of errors, the period Td of the first drive pulse Px is 2.25AL to 2.4AL, and preferably 2.29AL to 2.38AL, so that stable ink ejection is obtained and the print quality is good. It has been found.

  Next, a cancel pulse for suppressing vibration of ink in the ink chamber 23 after applying eight first drive pulses Px will be described.

  As shown in FIG. 2B, residual vibration A exists in the ink chamber 23 after the last first drive pulse Px is applied. If the next pixel is driven while the residual vibration A remains, ink ejection becomes unstable. Further, in order to drive at high speed, a cancel pulse for suppressing the residual vibration A is required.

  Hereinafter, a method for inputting the cancel pulse will be described. In the inkjet driving method of the present invention, the pulse width Tw of the first driving pulse Px is correlated with the pressure in the ink chamber 23 and the ink flow velocity. That is, when the pulse width Tw is increased, the pressure in the ink chamber 23 and the ink flow rate are also increased (see FIGS. 4 and 5). 4 shows the cycle Td of the first drive pulse Px = 5.7 μS and the pulse width Tw = 1.5 μS, and FIG. 5 shows the cycle Td of the first drive pulse Px = 5.7 μS and the pulse width Tw = 2.0 μS. In FIG. 5 where the pulse width Tw is large, it can be seen that the pressure in the ink chamber 23 and the ink flow velocity are larger than those in FIG.

  Further, as described above, the period Td of the first drive pulse Px is shifted from 2AL to suppress the increase in the pressure of the ink chamber 23 and the ink flow velocity at each drop. That is, even if the pulse width Tw of the first drive pulse Px is changed, the vibration cycle of the ink in the ink chamber 23 does not change.

  For example, when the pulse width Tcpw of the cancel pulse CP is 0.5 AL, the pulse width Tw of the first drive pulse Px is 2.0 μS, and the rear end of the last first drive pulse Px is used as a reference as in the conventional case. When the cancel pulse CP is input, residual vibration remains in the ink chamber 23 as shown in FIG. However, it was confirmed that there was no residual vibration in the ink chamber 23 when the pulse width Tw of the first drive pulse Px = 1.5 μS.

  In the present invention, as shown in FIG. 1B, the input timing of the cancel pulse CP is the intermediate position between the front end portion and the rear end portion of the last first drive pulse Px (that is, P8) and the cancel pulse. The time interval Tcp between the front end portion and the rear end portion of the CP is set to 0.5Td * AL, and the pulse width Tcpw is set to 0.5AL which is equal to or less than AL.

  In this way, the timing at which the cancel pulse CP is input is set to an intermediate position between the front end portion and the rear end portion of the last first drive pulse Px (that is, P8) and an intermediate position between the front end portion and the rear end portion of the cancel pulse CP. Thus, even if the pulse width Tw of the first drive pulse Px changes, the residual vibration in the ink chamber 23 can be canceled reliably (see FIGS. 4 and 5).

This is because the ink pressure in the ink chamber 23 changes at the center of the first drive pulse Px.
The timing at which the cancel pulse CP is input is the time between the intermediate position between the front end portion and the rear end portion of the last first drive pulse Px (that is, P8) and the intermediate position between the front end portion and the rear end portion of the cancel pulse CP. By setting the interval Tcp, the residual vibration in the ink chamber 23 can be sufficiently canceled.

  Next, simulation was performed on the pulse width Tcpw and the time interval Tcp of the cancel pulse CP. In this simulation, the pulse width Tcpw of the cancel pulse CP was set to AL (= 2.4 μS), and the simulation was performed in consideration of variations in the time interval Tcp. 7 and 8 show the results. FIG. 7 shows Tcp = (0.5Td−0.05) AL, and FIG. 8 shows Tcp = (0.5Td + 0.05) AL.

  Thus, it was found that if Tcp is in the range of (0.5Td−0.05) AL and (0.5Td + 0.05) AL, the residual vibration in the ink chamber 23 is canceled by the cancel pulse CP.

From the above simulation results, the print quality with and without the cancel pulse CP was compared under the conditions of Tc = 50 μS, Td = 5.7 μS, Tw = 2 μS, Tcp = 7 μS, Tcpw = 1.2 μS, and the experimental results are shown in Table 2. Shown in

That is, if Tc is shortened without applying the cancel pulse CP, the print quality is somewhat deteriorated. This is good printing at a certain voltage, but in the evaluation to see how much voltage margin there is for the voltage for good printing by raising and lowering the drive voltage, the voltage margin is better when there is a cancel pulse CP. Turned out to be great.

  In addition, it was found that the result of this experiment and the result of the magnitude of residual vibration in the simulation described above agree.

  Next, another method for inputting the cancel pulse will be described with reference to FIG. 1 (C), FIG. 9 and FIG. That is, the cancel pulse CP for expanding the ink chamber 23 is applied after the period Td from the rear end portion of the last first drive pulse Px (that is, P8). Since the ink is ejected when the pulse width Tcpw of the cancel pulse CP is the same as the pulse width Tw of the first drive pulse Px, the pulse width Tcpw of the cancel pulse CP is 1.4AL to 1.9AL, preferably 1.42AL to 1.84 AL.

  In this way, by applying the cancel pulse CP for expanding the ink chamber 23 after the last first drive pulse Px (that is, P8), the ink chamber 23 is maintained in the expanded state, and the ink flow rate is lowered. The residual vibration of the ink chamber is suppressed by returning the expanded state of the ink chamber 23 to the original state with good timing (see FIGS. 9 and 10).

  As shown in FIG. 9, when the pulse width Tcpw of the cancel pulse CP is set to 3.5 μS (= 3.5 / 2.4 = 1.46 AL), it has been found that the residual vibration of the ink chamber 23 can be suppressed as indicated by B.

  Further, as shown in FIG. 10, when the pulse width Tcpw of the cancel pulse CP is 4.5 μS (= 4.5 / 2.4 = 1.87 AL), it is found that the residual vibration of the ink chamber 23 can be suppressed as indicated by C. .

  Next, referring to FIG. 1D and FIG. 11, before the first first drive pulse Px (that is, P1), a prepulse PP that causes vibrations that do not cause ink to be ejected from the ink chamber 23 is applied. An example of preventing ink from being ejected in response to the drive pulse P1, that is, a decrease in the speed of the first drop will be described.

  The input timing of this prepulse PP is such that the time interval between the driving pulse P1 and the intermediate position between the front and rear ends of the prepulse is 2.25 to 2.4 AL (preferably 2.29 to 2.38 AL), and the pulse width Tb of this prepulse is The first drive pulse has a pulse width Tw or less.

  FIG. 11 shows a simulation result when the prepulse PP is introduced. In this simulation, AL = 2.4 μS, Td = 5.7 μS, Tw = 2.0 μS, and Tb = 1.0 μS (<Tw).

  As is apparent from FIG. 11, the prepulse PP causes the ink chamber 23 pressure and ink flow velocity to oscillate with a small amplitude as indicated by D, and is input after Td (= 5.7 μS). The amplitude is amplified by the first driving pulse Px (that is, P1), and ink is ejected. As is apparent from FIG. 11, by applying the pre-pulse PP, it is possible to increase the speed of the first drop and perform stable ejection.

  That is, in FIG. 10 where the prepulse PP is not applied, the ink flow velocity of the first drop is about 25 (m / s) as indicated by a, but in FIG. 11 where the prepulse PP is applied, the first drop ink is applied. The flow velocity exceeds 30 (m / s) as shown by b.

By the way, Table 3 shows the result of measuring the time when each drop ends when one pixel is formed by ejecting 8 drops of ink by the conventional method and the methods of claims 2 and 3.

  As shown in Table 3, in the past, it took 57.6 μS to eject 8 drops of ink. Therefore, it takes 57.6 / 8 = 7.2 μS per drop. Since AL = 2.4 μS, it takes 7.2 / 2.4 = 3 AL time.

  On the other hand, in the method of claim 2, it took 48.9 μS to discharge 8 drops. Therefore, it takes 48.9 / 8 = 6.1 μS per drop. Since AL = 2.4 μS, it takes 6.1 / 2.4 = 2.54 AL.

  Furthermore, in the method of claim 3, it took 49.1 μS to discharge 8 drops. Therefore, it takes 49.1 / 8 = 6.13 μS per drop. Since AL = 2.4 μS, 6.13 / 2.4 = 2.55 AL is required.

  Therefore, since one pixel can be formed in a shorter time than the conventional method, high-speed driving can be performed.

  Next, a head drive circuit used in the present invention will be described with reference to FIG. As shown in FIG. 14, the head drive circuit includes a memory 31, a control circuit 32, a shift register 33, a latch circuit 34, and waveform generation means 35. That is, the image data stored in the memory 31 is transferred to the shift register 33 via the control circuit 31. Then, after being latched by the latch circuit 34, the first drive pulse Px is output from the waveform generating means 35.

  In the case of an inkjet head that continuously discharges a plurality of droplets and constitutes one pixel as in the present invention, for example, the data to be printed is converted into a plurality of bits (multi-value data), and the multi-value data continuously. If the number of ejections is controlled in this way, high-speed and multi-tone printing can be realized.

  In the above-described embodiment, the AL = 2.4 μS ink jet head has been described. However, the present invention can also be applied to other AL ink jet heads.

  In the above embodiment, the experiment was performed using the share-mode type ink jet head, but the present invention can also be applied to an independent type ink jet head such as a Kaiser type ink jet head as shown in FIG.

The wave form diagram which shows the 1st drive pulse which concerns on the conventional drive pulse which concerns on one embodiment of this invention, and this invention. FIG. 4 is a waveform diagram of a first drive pulse of Td = 2AL and a relationship between an ink chamber and an ink flow velocity according to the same embodiment. The figure which shows the relationship between the waveform diagram of the 1st drive pulse of AL = 2.4 (micro | micron | mu) S, Td = 5.7 (micro | micron | mu) S, and Tw = 1.5 (micro | micron | mu) S which concerns on the embodiment, and an ink chamber and an ink flow velocity. The figure which shows the relationship between the waveform diagram which added the cancellation pulse to the waveform diagram of the 1st drive pulse of AL = 2.4 (micro | micron | mu) S, Td = 5.7 (micro | micron | mu) S, and Tw = 1.5 (micro | micron | mu) S concerning the embodiment, and an ink chamber and an ink flow velocity. The figure which shows the relationship between the waveform diagram which added the cancellation pulse to the waveform diagram of the 1st drive pulse of AL = 2.4 (micro | micron | mu) S, Td = 5.7 (micro | micron | mu) S, and Tw = 2.0 (micro | micron | mu) S concerning the embodiment, and an ink chamber and an ink flow velocity. The figure which shows the relationship between the waveform figure of the drive pulse to which the conventional cancellation pulse was added, and an ink chamber and an ink flow velocity. A cancel pulse of Tcpw = 2.4 μS [Tcp = (0.5Td−0.05) AL] is added to the waveform diagram of the first drive pulse of AL = 2.4 μS, Td = 5.7 μS, and Tw = 2.0 μS according to the same embodiment. FIG. 5 is a diagram showing the relationship between the waveform diagram and the ink chamber and the ink flow rate. A cancel pulse of Tcpw = 2.4 μS [Tcp = (0.5Td + 0.05) AL] is added to the waveform diagram of the first drive pulse of AL = 2.4 μS, Td = 5.7 μS, and Tw = 2.0 μS according to the same embodiment. FIG. 5 is a diagram showing the relationship between the waveform diagram and the ink chamber and the ink flow rate. A waveform diagram in which a cancel pulse of Tcpw = 3.5 μS is added to the waveform diagram of the first drive pulse of AL = 2.4 μS, Td = 5.7 μS, and Tw = 2.0 μS according to the embodiment, the ink chamber, and the ink flow velocity. The figure which shows a relationship. A waveform diagram in which a cancel pulse of Tcpw = 4.5 μS is added to the waveform diagram of the first drive pulse of AL = 2.4 μS, Td = 5.7 μS, and Tw = 2.0 μS according to the embodiment, an ink chamber, and an ink flow velocity. The figure which shows a relationship. Relationship between the waveform diagram of the first drive pulse with AL = 2.4 μS, Td = 5.7 μS, and Tw = 2.0 μS added with the pre-pulse with Tb = 1.0 μS, and the ink chamber and ink flow velocity according to the embodiment FIG. FIG. 3 is a diagram illustrating a structure of a Kaiser-type inkjet head according to the same embodiment. FIG. 3 is a diagram illustrating a structure of a share mode type inkjet head according to the embodiment. FIG. 3 is a control block diagram of the ink jet head according to the embodiment.

Explanation of symbols

  21 ... partition wall, 22 ... drive waveform generating means, 23 ... ink chamber, 24 ... nozzle, 25 ... common ink chamber, 26 ... common ink chamber.

Claims (2)

A nozzle communicating with the ink chamber containing the ink, and an actuator for changing the volume of the ink chamber according to a driving waveform, and expanding the ink chamber by the operation of the actuator; In the ink jet recording apparatus for forming one pixel by continuously ejecting ink droplets from the nozzle a plurality of times by continuously applying a driving pulse for returning the actuator to the actuator a plurality of times,
When the time for the pressure wave in the ink chamber to propagate from one end to the other end in the ink discharge direction is AL,
The drive pulse for expanding the ink chamber is continuously supplied to the actuator with a pulse period Td of 2.25 AL to 2.4 AL, and a plurality of inks are continuously ejected to form one pixel. Like
A cancel pulse for suppressing the residual vibration of the ink chamber after the last drive pulse of the plurality of drive pulses forming one pixel is defined as a time interval between the front end of the last drive pulse and the front end of the cancel pulse as Td. The pulse width of this cancel pulse is 1.4AL to 1.9AL, and is supplied to the actuator after the last drive pulse.
A method for driving an ink jet recording apparatus . A nozzle communicating with the ink chamber containing the ink, and an actuator for changing the volume of the ink chamber according to a driving waveform, and expanding the ink chamber by the operation of the actuator; In the ink jet recording apparatus for forming one pixel by continuously ejecting ink droplets from the nozzle a plurality of times by continuously applying a driving pulse for returning the actuator to the actuator a plurality of times,
When the time during which the pressure wave in the ink chamber propagates from one end to the other end in the ink ejection direction is defined as AL, the drive pulse whose time width for expanding the ink chamber is equal to or less than AL is set to a pulse period Td of 2.25 to 2.4AL. Continuously supplying the actuator, and before the first drive pulse of the plurality of drive pulses, a pre-pulse that causes ink vibrations to the extent that ink is not ejected is applied to the actuator, and the front and rear ends of the pre-pulse A time interval between the intermediate position of the first part and the intermediate position of the front end part and the rear end part of the first drive pulse is 2.25 to 2.4 AL, and the pulse width of the pre-pulse is equal to or less than the pulse width of the drive pulse,
A method for driving an ink jet recording apparatus .

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