JP2000085123A - Ink jet recording apparatus and recording method - Google Patents

Abstract

(57) Abstract: A drive signal having two types of drive pulses P1 and P2 for ejecting small ink droplets and large ink droplets having different ejection amounts from nozzles 2 of an inkjet head 1 is generated. While moving the inkjet head 1 relative to the recording paper 41 in the main scanning direction, one or two of the driving pulses P1 and P2 are selectively input to the actuator 10 to operate the actuator 10. In this case, regardless of whether only small ink droplets or large ink droplets are ejected or both ink droplets are ejected, ink droplets are always accurately landed at a desired position to improve image quality. SOLUTION: Small ink droplets and large ink droplets are ejected in this order, and the ejection speed of large ink droplets is made faster than that of small ink droplets, so that the two ink droplets are united at substantially the same position on recording paper 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an ink jet recording apparatus and a recording method for discharging a plurality of ink droplets having different discharge amounts from the same nozzle of an ink jet head.

[0002]

2. Description of the Related Art In recent years, as shown in, for example, Japanese Patent Application Laid-Open No. 10-81012, an ink jet recording apparatus has been proposed in which a plurality of ink droplets having different discharge amounts are discharged from the same nozzle. The inkjet recording apparatus includes an ink jet head having a pressure chamber containing ink, a nozzle communicating with the pressure chamber, and a pressure applying unit that applies pressure to the pressure chamber to eject ink droplets from the nozzle. A relative moving means for relatively moving the ink jet head and the recording paper;
Then, a drive signal having a plurality of types of drive pulses for ejecting a plurality of ink droplets having different ejection amounts from the nozzles of the inkjet head is generated, and the inkjet head and the recording paper are relatively moved by the relative moving means. During the movement, one or more kinds of drive pulses of the drive signal are selectively input to the pressure application unit to operate the pressure application unit. By doing so, it is possible to perform multi-gradation printing by variably controlling the diameter of the dots recorded on the recording paper.

On the other hand, as shown in, for example, US Pat. No. 5,285,215, the ejection speed of ink droplets ejected later is made faster than that of ink droplets ejected first, so that the ink droplets ejected from the same nozzle are ejected. It has been proposed to combine the two ink droplets before they land on recording paper to generate large ink droplets.

[0004]

However, in the case of the former proposal (Japanese Patent Laid-Open No. Hei 10-81012), since the speed of the ink droplets is not considered, the large ink droplets and the small ink droplets are separated. Landed on the recording paper in a shifted state,
It becomes an oval dot. For this reason, it is difficult to improve the image quality.

On the other hand, the latter proposed example (US Pat. No. 5,285,285)
No. 215), a dot close to a perfect circle can be obtained,
When the ink droplets are merged, the speed of the merged ink droplets is the combined speed of the two ink droplets. Therefore, after the merged ink droplets, the flying direction of the ink droplets changes differently from when only one ink droplet is ejected. Would. For this reason, when dots recorded by one ink droplet and dots recorded by two ink droplets are adjacent to each other, there is a problem that their relative positions are shifted.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to perform multi-tone printing by discharging a plurality of ink droplets having different discharge amounts from the same nozzle. An object of the present invention is to improve the image quality by always accurately landing ink droplets at desired positions regardless of whether one ink droplet is ejected or a plurality of ink droplets.

[0007]

In order to achieve the above object, according to the present invention, a plurality of ink droplets are ejected in ascending or descending order, and the ejected ink droplets are placed on a recording paper. At approximately the same position.

More specifically, according to the first aspect of the present invention, a pressure chamber containing ink, a nozzle communicating with the pressure chamber, and a pressure for applying a pressure to the pressure chamber to discharge an ink droplet from the nozzle. An inkjet head having an application unit; a relative moving unit configured to relatively move the inkjet head and the recording paper; and a plurality of types of driving for ejecting a plurality of ink droplets having different ejection amounts from nozzles of the inkjet head. One of drive signal generation means for generating a drive signal having a pulse, and one of drive signals generated by the drive signal generation means when the ink jet head and the recording paper are relatively moved by the relative movement means. Alternatively, a plurality of types of driving pulses are selectively inputted to the pressure applying means to activate the pressure applying means. It assumes ink jet recording apparatus and means.

When a plurality of drive pulses of a drive signal are input to the pressure applying means by the energizing means, a plurality of ink droplets are ejected in ascending order of the ejection amount, and the plurality of ejected ink droplets are ejected. It is assumed that they are combined at substantially the same position on the recording paper and one dot is recorded with a plurality of ink droplets.

Thus, when a plurality of ink droplets are ejected from the same nozzle, the respective ink droplets land on the recording paper without changing the flight direction in the middle, unlike the case where the ink droplets are united in the air. Therefore, each of them travels the same flight path as when only one ink droplet is ejected. Therefore, when a dot recorded by one ink droplet and a dot recorded by a plurality of ink droplets are adjacent to each other, the relative positions of the two dots are not shifted, and the dots are accurately landed on the recording paper. Can be. In addition, since the ink droplets are merged at substantially the same position on the recording paper, the merged dot becomes a dot that is close to a perfect circle. On the other hand, since the plurality of ink droplets are ejected in ascending order of the ejection amount, it is easy to combine the plurality of ink droplets at substantially the same position on the recording paper. That is, for example, if the maximum voltage maintaining time of the drive pulse is increased, both the ejection speed and the ejection amount can be increased, and the ejection speed can be easily increased as the ejection amount of the ink droplet increases. Therefore, gradation recording with good image quality can be easily performed.

According to a second aspect of the present invention, there is provided a pressure chamber for accommodating ink, a nozzle communicating with the pressure chamber, and pressure applying means for applying pressure to the pressure chamber to eject ink droplets from the nozzle. A driving signal having a plurality of types of driving pulses for ejecting a plurality of ink droplets having mutually different ejection amounts from nozzles of the inkjet head, a relative moving unit for relatively moving the inkjet head and the recording paper, and an inkjet head; A drive signal generating means for generating the one or more types of drive signals generated by the drive signal generating means when the ink jet head and the recording paper are relatively moved by the relative moving means. Energizing means for selectively inputting a pulse to the pressure applying means to operate the pressure applying means. It assumes ink jet recording apparatus.

When a plurality of drive pulses of a drive signal are input to the pressure applying means by the energizing means, a plurality of ink droplets are ejected in descending order of ejection amount, and the plurality of ejected ink droplets are ejected. It is assumed that they are combined at substantially the same position on the recording paper and one dot is recorded with a plurality of ink droplets.

According to the present invention, similarly to the first aspect of the present invention, regardless of whether one ink droplet is ejected or a plurality of ink droplets are ejected, the ink droplet is accurately landed on the recording paper. And a dot close to a perfect circle is obtained. Since a plurality of ink droplets are ejected in descending order of the ejection amount, the ejection speed must be reduced for ink droplets having a large ejection amount, but the voltage gradient at the rising of the drive pulse, the maximum voltage, and the maximum voltage maintenance time By adjusting such factors, a plurality of ink droplets can be combined at substantially the same position on the recording paper. In addition, satellites are likely to be generated when the ink droplets have a large discharge amount at the time of discharge. However, according to the present invention, the discharge speed can be made relatively slow, so that the generation of satellites can be suppressed. Further, although the straightness of an ink droplet having a small ejection amount becomes unstable, the ejection speed can be made relatively high in the present invention, so that the flight stability can be improved. Therefore, the image quality can be further improved.

According to a third aspect of the present invention, in the first or second aspect of the present invention, only one type of driving pulse corresponding to the ink droplet having the largest ejection amount in the driving signal is input to the pressure applying unit by the energizing unit. A normal mode configured to perform pass printing, and selectively inputting one or more types of drive pulses of a drive signal to the pressure applying unit by an energizing unit and setting the drive frequency for one dot printing to the normal mode. Mode switching means for switching at least two modes from a high-quality mode configured to perform two-pass printing so as to be の of the mode is provided.

For this reason, the carriage speed (the relative movement speed between the ink jet head and the recording paper) is usually limited. Therefore, in two-pass printing, the driving frequency must be reduced. When printing dots, a lower drive frequency is more convenient, so in the high image quality mode, the image quality can be further improved by two-pass printing while maintaining the printing speed to the maximum. Further, by setting the driving frequency for one dot recording in the high image quality mode to １ ／ of that in the normal mode, it is not necessary to change the carriage speed depending on the mode.

According to a fourth aspect of the present invention, in the first or second aspect of the invention, the drive signal has two types of drive pulses,
A normal mode in which only one type of driving pulse corresponding to an ink droplet having a large ejection amount in the driving signal is input to the pressure applying unit by the energizing unit; and one or two types of driving signal by the energizing unit. A mode switching unit that switches between at least two modes, that is, a high image quality mode configured to obtain three gradation values by selectively inputting different types of drive pulses to the pressure application unit, The time required for one-dot recording is T1, the time required for one-dot recording in the high-quality mode is T2, and two kinds of driving pulses of a driving signal are input to the pressure applying means by the energizing means in the high-quality mode. The time from the start of the rise of the first drive pulse to the start of the rise of the second drive pulse is defined as T3. <2 × T1 and T3 <T1, and the second drive pulse rises in a state where the pressure chamber is not completely filled with ink after the rise of the first drive pulse. It is assumed that

By doing so, the recording speed in the high image quality mode can be improved as much as possible. If the second drive pulse is started up in a state where the ink is not completely filled in the pressure chamber (a state in which the ink is not in time for refilling), the ejection amount of the ink droplet ejected by the second drive pulse becomes small. Since the ejection amount is determined by T3, the total amount with the first ink droplet can be made substantially constant unless T3 is changed, and there is no variation for each dot in the high image quality mode. On the other hand, by setting the time T1 required for one-dot recording in the normal mode so that refilling can be performed in time, it is possible to prevent variations between dots in the normal mode.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the drive signal includes a first drive pulse for discharging the first ink droplet and a discharge amount larger than that of the first ink droplet. And a second driving pulse for discharging the second ink droplet. After the first ink droplet is discharged by the first driving pulse, the ink meniscus at the tip end of the nozzle moves with respect to the initial position. The second drive pulse rises to eject the second ink droplet when the second ink droplet protrudes toward the ejection side.

That is, after the ink is completely filled in the pressure chamber, the ink meniscus oscillates toward the ejection side and the non-ejection side with respect to the initial position, but when the ink meniscus projects toward the ejection side with respect to the initial position. Since the second drive pulse rises first, there is no need to wait for the rise of the second drive pulse until the vibration stops, and the ejection amount of the second ink droplet can be increased as much as possible. Therefore, the dynamic range can be expanded while improving the recording speed.

According to a sixth aspect of the present invention, in the first or second aspect of the present invention, the rising start interval between a plurality of types of drive pulses in the drive signal can be changed.

Thus, even if the viscosity or the like of the ink changes due to a change in the environment such as the temperature and the ejection amount or ejection speed of the ink droplet changes, the ink droplet can be accurately formed by appropriately changing the rising start interval. It can be made to land at a position.

According to a seventh aspect of the present invention, in the first or second aspect, the pressure applying means includes a diaphragm provided in the pressure chamber and a piezoelectric element for vibrating the diaphragm. I do. In this way, it is possible to easily obtain a pressure applying unit that can easily control the ejection amount and the ejection speed of the ink droplet.

According to an eighth aspect of the present invention, in the seventh aspect of the invention, at least a drive pulse for ejecting an ink droplet having a minimum ejection amount in the drive signal is set at a minimum potential from an intermediate potential between the minimum potential and the maximum potential. A voltage drop waveform that drops to a potential, a minimum potential maintenance waveform that maintains a minimum potential, a potential rising waveform that rises from a minimum potential to a maximum potential, a maximum potential maintenance waveform that maintains a maximum potential, and the intermediate potential from the maximum potential And an intermediate potential return waveform that returns to

According to the present invention, since the ink droplet having the smallest ejection amount is ejected by so-called "pulling", the ejection speed can be increased. Therefore, it is possible to improve the flight stability of the ink droplet having the minimum ejection amount.

According to a ninth aspect of the present invention, in the first or second aspect of the present invention, a counter electrode disposed so as to face the ink jet head with the recording paper interposed therebetween, and the ink in the pressure chamber of the ink jet head and the counter electrode. Voltage applying means for applying a voltage between the electrodes.

By doing so, an electrostatic field is applied between the ink jet head and the opposing electrode, and electric charges are induced in the ink, so that the ink droplets ejected from the nozzles are accelerated by the electrostatic field toward the recording paper. To fly. As a result, the ejection speed of the ink droplets can be increased, and in particular, the flying stability of the ink droplets having a small ejection amount can be improved.

According to a tenth aspect of the present invention, in the ninth aspect of the present invention, the voltage applied between the ink in the pressure chamber of the ink jet head and the counter electrode can be changed by the voltage applying means. It is assumed that
Thus, even if the environment such as the temperature changes, the ejection speed of the ink droplets can be stabilized by appropriately changing the voltage.

In the eleventh aspect of the present invention, a plurality of pressure chambers for accommodating ink, a plurality of nozzles respectively communicating with the pressure chambers, and a pressure is applied to the pressure chambers to eject ink droplets from the nozzles. An inkjet head having a plurality of pressure applying means, and a relative moving means for relatively moving the inkjet head and the recording paper,
It is assumed that the ink jet recording apparatus is such that the pressure applying means is operated when the ink jet head and the recording paper are relatively moved by the relative moving means.

At least the first and second nozzles of the plurality of nozzles are provided so as to be arranged in the direction of relative movement between the ink jet head and the recording paper by the relative moving means. While ejecting one ink droplet, a second ink droplet having a larger ejection amount than the first ink droplet is ejected from the second nozzle and substantially the same position on the recording paper as the first ink droplet. And one dot is recorded with a plurality of ink droplets.

According to the present invention, similarly to the first and second aspects of the present invention, even when only the first or second ink droplet is ejected, the first and second ink droplets are ejected. In this case, the ink droplet can be accurately landed on the recording paper, and a dot close to a perfect circle can be obtained. Since the ink droplets are ejected separately from the first and second nozzles, the ejection timing, ejection amount, ejection speed, and the like of each ink droplet are more easily controlled than in the first and second aspects of the present invention.
The first and second ink droplets can be easily combined at substantially the same position on the recording paper.

According to a twelfth aspect of the present invention, there is provided a pressure chamber for accommodating ink, a nozzle communicating with the pressure chamber, and pressure applying means for applying pressure to the pressure chamber to eject ink droplets from the nozzle. An inkjet head is provided, and a drive signal having a plurality of types of drive pulses for ejecting a plurality of ink droplets having different ejection amounts from the nozzles of the inkjet head is generated. An ink jet recording method is an invention in which any one or a plurality of types of driving pulses of the driving signal are selectively input to the pressure applying unit while moving, and the pressure applying unit is operated.

According to the present invention, when a plurality of types of drive pulses of the drive signal are input to the pressure applying means, a plurality of ink droplets are ejected in ascending order of ejection amount, and the plurality of ejected ink droplets are ejected. The droplets are combined at substantially the same position on the recording paper so that one dot is recorded with a plurality of ink droplets. Thus, the same function and effect as the first aspect of the invention can be obtained.

According to a thirteenth aspect of the present invention, there is provided a pressure chamber for accommodating ink, a nozzle communicating with the pressure chamber, and a pressure applying means for applying pressure to the pressure chamber to eject ink droplets from the nozzle. An inkjet head is provided, and a drive signal having a plurality of types of drive pulses for ejecting a plurality of ink droplets having different ejection amounts from the nozzles of the inkjet head is generated. An ink jet recording method in which any one or a plurality of types of drive pulses of the drive signal is selectively input to the pressure application unit while moving, and the pressure application unit is activated.

When a plurality of types of drive pulses of the drive signal are input to the pressure applying means, a plurality of ink droplets are ejected in descending order of the ejection amount, and the ejected ink droplets are separated from each other. The dots are combined at substantially the same position on the recording paper so that one dot is recorded with a plurality of ink droplets. Thus, the same function and effect as the second aspect of the invention can be obtained.

[0035]

(Embodiment 1) FIG. 1 shows an ink jet recording apparatus according to Embodiment 1 of the present invention. And an inkjet head 1 for ejecting the ink to the printer. The ink jet head 1 is supported and fixed on a carriage 16. This carriage 16
The carriage motor 28 not shown in FIG.
(See FIG. 6). The carriage motor 28 guides the inkjet head 1 and the carriage 16 on a carriage shaft 17 extending in the main scanning direction (X direction shown in FIGS. 1 and 2), and reciprocates in that direction. It is supposed to. The carriage 16 and the carriage shaft 17
The carriage motor 28 constitutes a relative moving unit that relatively moves the inkjet head 1 and the recording paper 41.

The recording paper 41 is sandwiched between two transport rollers 42 which are driven to rotate by a transport motor 26 (not shown in FIG. 1) (see FIG. 6). The sheet is transported in a sub-scanning direction (Y direction shown in FIGS. 1 and 2) perpendicular to the main scanning direction.

As shown in FIGS. 2 to 5, the ink jet head 1 includes a plurality of pressure chambers 4 for storing ink,
It has a plurality of nozzles 2 communicating with the pressure chambers 4 and a plurality of actuators 10 (pressure applying means) for applying pressure to the pressure chambers 4 and ejecting ink droplets from the nozzles 2 respectively. This actuator 10
As will be described later, a so-called flexural vibration type piezoelectric element 13 is used, which contracts and expands the pressure chamber 4 and discharges ink droplets from the nozzle 2 by a change in pressure of the pressure chamber 4 accompanying the contraction and expansion. 4 is filled with ink.

As shown in FIG. 1, the pressure chambers 4 are formed in the ink jet head 1 in a long groove shape so as to extend in the main scanning direction, and are arranged at predetermined intervals in the sub scanning direction. Has been established. At one end (the right end in FIG. 2) of the pressure chamber 4, the nozzles 2 are provided on the lower surface of the inkjet head 1 so as to open at predetermined intervals in the sub-scanning direction.

One end of an ink supply path 5 is connected to the other end (the left end in FIG. 2) of the pressure chamber 4, respectively.
The other end of each ink supply path 5 is connected to an ink supply chamber 3 provided to extend in the sub-scanning direction.

As shown in FIG. 3, the ink jet head 1 has a nozzle plate 6 in which the nozzles 2 are formed, a partition wall 7 for partitioning the pressure chambers 4 and the ink supply passages 5, and an actuator. 10 are sequentially laminated. This nozzle plate 6 has a thickness of 2
The partition wall 7 is made of a polyimide plate having a thickness of 280 μm.
It is composed of a stainless steel laminated plate of μm.

The actuator 10 is shown in FIGS.
As shown in an exaggerated manner in FIG.
1, a piezoelectric element 13 for vibrating the diaphragm 11, and an individual electrode 14 are sequentially laminated. The vibration plate 11 is made of a chrome plate having a thickness of 2 μm, and also has a function as a common electrode for applying a voltage to each piezoelectric element 13 together with the individual electrodes 14. The piezoelectric element 13 is provided corresponding to the pressure chamber 4 and has a thickness of 3 mm.
It is an ultra-thin one made of PZT (lead zirconate titanate) having a thickness of μm. The individual electrodes 14 are made of a platinum plate having a thickness of 0.1 μm, and the overall thickness of the actuator 10 is about 5 μm. Note that an insulating plate 15 made of polyimide is provided between the piezoelectric elements 13 (individual electrodes 14) adjacent to each other.

Next, the configuration of the driving device 20 of the ink jet recording apparatus will be described with reference to the block diagram of FIG. In other words, the driving device 20 includes a control unit 21 including a CPU.
And an RO storing routines for various data processing, etc.
M22, a RAM 23 for storing various data and the like, driver circuits 25 and 27 for driving and controlling the transport motor 26 and the carriage motor 28, and motor control circuits 24 and 24, respectively, and a data receiving circuit for receiving print data 29, and a drive signal generation circuit 30 as drive signal generation means.

As shown in FIG. 7, the drive signal generating circuit 30 has two types of first and second ink jet heads for ejecting small ink droplets and large ink droplets having different ejection amounts from the same nozzle 2 of the ink jet head 1, respectively. A drive signal having the first and second drive pulses P1 and P2 is generated. That is, since the first drive pulse P1 of this drive signal has a maximum voltage sustaining time shorter than the second drive pulse P2, when the first drive pulse P1 is input to the actuator 10 as described later, the ejection amount In addition, a small ink droplet having a relatively low ejection speed is ejected from the nozzle 2. On the other hand, when the second drive pulse P2 is input to the actuator 10, a large ink droplet having a larger ejection amount and ejection speed than the small ink droplet is ejected. The first and second drive pulses P1 and P2 repeatedly appear at a predetermined frequency f (drive frequency), and the first drive pulse P1
Drive pulse P2 after T time from the start of
Is started to rise.

The drive signal generation circuit 30 is connected to a selection circuit 31 to which the drive signal generated by the drive signal generation circuit 30 is input, and the selection circuit 31 is connected to the actuator 10. The selection circuit 31 outputs one of the first and second drive pulses P1 and P2 of the drive signal generated by the drive signal generation circuit 30 when the inkjet head 1 is moving in the main scanning direction together with the carriage 16. One or two types are selectively input to the actuator 10 to constitute an energizing means for operating the actuator 10. That is, when only the first drive pulse P1 is selected by the selection circuit 31, a voltage is applied between the diaphragm 11 as the common electrode of the actuator 10 and the individual electrode 14 corresponding to the first drive pulse P1. This allows the piezoelectric element 13
When the pressure is applied to the pressure chamber 4 and only the small ink droplet is ejected from the nozzle 2 of the inkjet head 1 at the predetermined frequency f, while the second drive pulse P2 alone is selected, the nozzle From 2 only large ink droplets are ejected at the frequency f.

Further, when both the first and second drive pulses P1 and P2 are selected by the selection circuit 31, 1
In the cycle, first, a small ink droplet is ejected from the nozzle 2 by the first drive pulse P1, and the first drive pulse P1
Drive pulse P after a lapse of T time from the start of
2, large ink droplets are ejected from the same nozzle 2. In this case, the small ink droplet and the large ink droplet are combined at substantially the same position on the recording paper 41 so that one dot is recorded by both ink droplets. Therefore, a small dot is formed only by the small ink droplet, a medium dot is formed only by the large ink droplet, and a large dot is formed by both the small ink droplet and the large ink droplet. When included, four gradation values) can be obtained.

The operation of the ink jet recording apparatus having the above configuration will be described. First, the data receiving circuit 29
Receives the image data, the control unit 21 controls the motor control circuit 2 based on the processing routine stored in the ROM 22.
4 and the transport motor 26 via the driver circuits 25 and 27
And the carriage motor 28, respectively.
The first and second drive pulses P are supplied to the drive signal generation circuit 30.
A drive signal having P1 and P2 is generated. Further, the control unit 21 outputs information of a drive pulse to be selected to the selection circuit 31 based on the image data.

Next, the selection circuit 31 selects one or two of the first and second drive pulses P1 and P2 based on the information and inputs the selected one to the actuator 10.
As a result, only small ink droplets, only large ink droplets, or both are ejected from the nozzles 2 of the inkjet head 1.

When both the small ink droplet and the large ink droplet are ejected, as shown in FIG. 8, the small ink droplet is moved at the moving speed (carriage speed) Vc of the carriage 16 in the main scanning direction and the ejection speed Vd1. Paper 4 at the combined speed V1
Fly almost linearly toward 1. Next, after a lapse of T time from the ejection of the small ink droplet, the carriage 16
The ink droplet moves in the main scanning direction by T, and a large ink droplet flies from the large ink droplet substantially linearly toward the recording paper 41 at a combined speed V2 of the carriage speed Vc and the ejection speed Vd2. Then, the ejection speeds Vd1 and Vd2 of the small ink droplet and the large ink droplet, and the second driving pulse P1 from the rising start of the first driving pulse P1 so that the flying lines of the small ink droplet and the large ink droplet intersect on the recording paper 41. The time T up to the start of the rise of the drive pulse P2 is set in advance, and the small ink droplet and the large ink droplet are united at substantially the same position on the recording paper 41, and one dot is recorded by both ink droplets. The time T from the start of the rise of the first drive pulse P1 to the start of the rise of the second drive pulse P2 is longer than the time when the ink is completely filled into the pressure chamber 4 after the ejection of the small ink droplet. It is set long.

Therefore, in the above-described embodiment, when both the small ink droplet and the large ink droplet are ejected, the two ink droplets are merged on the recording paper 41, which is different from the case where they are merged in the air. The small ink droplet and the large ink droplet both fly substantially linearly until they land on the recording paper 41, and follow the same flight path as when only the small ink droplet or the large ink droplet is ejected. To land. For this reason, when the dot recorded with only the small ink droplet or the large ink droplet and the dot recorded with both the small ink droplet and the large ink droplet are adjacent to each other, the relative positions of the two dots do not shift. Thus, the recording paper 41 can be accurately landed. In addition, since the small ink droplet and the large ink droplet are united at substantially the same position on the recording paper 41,
Dots recorded in both cases are close to perfect circles.

Since the ink droplets are ejected in the order of small ink droplets and large ink droplets, the first and second drive pulses P
By adjusting each of the maximum voltage holding times of P1 and P2,
By making the ejection speed of the large ink droplets faster than that of the small ink droplets, the two ink droplets can be combined at substantially the same position on the recording paper 41. Therefore, gradation recording with good image quality can be easily performed.

In the first embodiment, the time T from the start of the rise of the first drive pulse P1 to the start of the rise of the second drive pulse P2 (the start of the rise of the first and second drive pulses P1 and P2). Although the interval is fixed, the time T may be changed. In this way, even if the viscosity or the like of the ink changes due to changes in the environment such as temperature, and the ejection amount and ejection speed of both ink droplets change, the rising start interval is appropriately changed to accurately detect both ink drops. It can be made to land at an appropriate position.

In the first embodiment, two ink droplets, a small ink droplet and a large ink droplet, are ejected from the same nozzle 2. However, three or more ink droplets having different ejection amounts are ejected from the same nozzle 2. 2 may be discharged. In this case, the ink droplets are ejected in ascending order of the ejection amount, and all the ejected ink droplets are connected to the recording paper 41.
The dots may be combined at approximately the same position above to record one dot with three or more ink droplets.

(Embodiment 2) FIG. 9 shows Embodiment 2 of the present invention.
, And the second drive pulse P2 is
Rise before the drive pulse P1 of the
The ink is ejected in the order of small ink droplets.

That is, in the second embodiment, the rising angle of the first drive pulse P1 is changed to the second drive pulse P2.
When both the small ink droplets and the large ink droplets are ejected so that the small ink droplets are ejected faster than the large ink droplets, the two ink droplets are recorded as in the first embodiment. They are combined at substantially the same position on the paper 41.

Therefore, also in the second embodiment,
Even when only a small ink droplet or a large ink droplet is ejected, or even when both ink droplets are ejected, the ink droplet can be accurately landed on the recording paper 41,
A dot close to a perfect circle is obtained. Then, the first embodiment
Unlike the above, since large ink droplets are ejected in the order of small ink droplets, the ejection speed of large ink droplets and the ejection speed of small ink droplets are increased, thereby suppressing the occurrence of satellites when ejecting large ink droplets. And the flying stability of small ink droplets can be improved. Therefore, the image quality can be improved as compared with the first embodiment.

In the second embodiment, similarly to the first embodiment, the time from the start of the second drive pulse P2 to the start of the first drive pulse P1 may be changed. Alternatively, three or more ink droplets having different discharge amounts may be discharged from the same nozzle 2.

(Embodiment 3) FIG. 10 shows Embodiment 3 of the present invention, and a small ink droplet (first
, And large ink drops (second ink drops) in this order. This is an improvement in the start-up time of the second drive pulse P2 for discharging large ink drops.

That is, as shown in FIG.
Immediately after a small ink droplet is ejected by the first drive pulse P1, the ink meniscus 45 at the tip of the ink is largely depressed from the initial position (reference position) indicated by the solid line to the non-ejection side indicated by the one-dot chain line. Is returned to the original initial position as the pressure chamber 4 is filled.
The ink meniscus 45 oscillates toward the ejection side and the non-ejection side with respect to the initial position after the ink is completely filled (in FIG. 10, the two-dot chain line indicates the case where the second drive pulse P2 is not input to the actuator 10). (Vibration of the ink meniscus 45).

In the third embodiment, the second drive pulse P2 starts from the rising start of the first drive pulse P1.
The time T up to the start of the rise of the ink meniscus 4
The second drive pulse P2 rises when 5 protrudes toward the ejection side from the initial position, and a large ink droplet is ejected.

By doing so, it is not necessary to wait for the rise of the second drive pulse P2 until the vibration of the ink meniscus 45 stops, and the ejection amount of large ink droplets can be increased as much as possible. Therefore, the dynamic range can be expanded while improving the recording speed.

(Embodiment 4) FIG. 12 shows Embodiment 4 of the present invention, wherein the first drive pulse P1 for discharging a small ink droplet in the drive signal is between the minimum potential (0 V) and the maximum potential. Voltage drop waveform P11 falling from the intermediate potential to the minimum potential, and a minimum potential maintenance waveform P maintaining the minimum potential.
12, a potential rising waveform P13 rising from the minimum potential to the maximum potential, and a maximum potential maintaining waveform P1 maintaining the maximum potential
4 and an intermediate potential return waveform P15 for returning from the maximum potential to the intermediate potential.

Therefore, in the fourth embodiment, the ink meniscus 45 is temporarily recessed to the non-ejection side by the voltage drop waveform P11 and the minimum potential maintenance waveform P12, and from this state, small ink droplets are ejected by the potential rise waveform P13. (So-called "pushing"), the approach section of the small ink droplet becomes longer, and the ejection speed can be increased. Therefore, the flying stability of the small ink droplet can be improved.

In the fourth embodiment, the second drive pulse P2 for ejecting large ink droplets rises from the intermediate potential to the maximum potential. As shown by a broken line, the potential may be decreased from the intermediate potential to the minimum potential, maintained at the minimum potential, and then increased from the minimum potential to the maximum potential. In this case, when the potential is lowered from the intermediate potential to the minimum potential, it is desirable to make the gradient gentler than the voltage drop waveform P11 of the first drive pulse P1 so as not to reduce the ejection amount of the large ink droplet.

In the fourth embodiment, the minimum potential is set to 0.
Although V is set, the intermediate potential may be set to 0 V and the minimum potential may be set to a minus potential. However, in this case, two power supplies are required, and the fourth embodiment is more preferable.

Further, in the fourth embodiment, as in the first embodiment, the first drive pulse P1 is started before the second drive pulse P2 to eject small ink drops and large ink drops in this order. However, large ink droplets and small ink droplets may be ejected in this order as in the second embodiment (the same applies to the following fifth to seventh embodiments).

In the fourth embodiment as well, three or more ink droplets having different ejection amounts may be ejected from the same nozzle 2. In this case, at least an ink droplet having the smallest ejection amount is ejected. What is necessary is just to comprise the drive pulse for making it possible to "pull" like Embodiment 4 mentioned above.

(Embodiment 5) FIG. 13 shows Embodiment 5 of the present invention (note that the same parts as those in FIG. 6 are denoted by the same reference numerals and detailed description thereof is omitted). Mode switch 3 that allows the user of the ink jet recording apparatus to switch between the two modes
5 (mode switching means).

That is, in this embodiment, information on the mode selected by the mode changeover switch is input to the selection circuit 31, and the selection circuit 31 uses the mode information to perform the first and second drive. Pulse P1,
The selection of P2 is made different. That is, in the normal mode, only one type of the second drive pulse P2 corresponding to the large ink droplet is input to the actuator 10 regardless of the information of the image data. One or two of the first and second drive pulses P1 and P2 of the drive signal are selectively input to the actuator 10 based on data information.

The selection circuit 31 and the actuator 10
A driving frequency changing circuit 36 is provided between the control signal and the driving frequency changing circuit 36. The mode information of the mode changeover switch 35 is also input to the driving frequency changing circuit 36. The driving frequency changing circuit 36 changes the driving frequency for one dot recording based on the mode information. That is, in the high image quality mode, one dot is recorded at the same frequency f as in the first to fourth embodiments, whereas in the normal mode, one dot is recorded at twice the frequency. As a result, as shown in FIG. 14, in the normal mode, the second drive pulse P2 has a period T1 (= １ ／).
The input is input to the actuator 10 in f).

Further, the mode information of the mode changeover switch 35 is also input to the control unit 21, so that the normal mode performs one-pass printing and the high-quality mode performs two-pass printing. In the two-pass printing, as shown in FIG. 15, in the first pass when the inkjet head 1 (carriage 16) is moved in the main scanning direction, printing is performed at every other dot (dots filled in black).
It is to fill in the space between the passes, part 2
At the time of the pass, the recording paper 41 is transported by the transport motor 26 so that the inkjet head 1 is shifted by several dots in the sub-scanning direction, so that the discharge variation of each nozzle 2 can be reduced.

As described above, in both the normal mode and the high image quality mode, the carriage speed is set to twice the carriage speed Vc in the first to fourth embodiments. If the drive frequency is set to be the same as that in the normal mode even in the high image quality mode, the carriage speed must be further increased in the high image quality mode. It is also difficult to discharge both.
Therefore, according to the fifth embodiment, the carriage speed can be kept constant irrespective of the mode, and in the high image quality mode, the image quality can be improved by two-pass printing while maintaining the printing speed to the maximum. It can be further improved.

In the fifth embodiment, three or more ink droplets having different discharge amounts may be discharged from the same nozzle 2. In this case, in the normal mode, the ink droplet having the maximum discharge amount is discharged. In this case, only one type of drive pulse corresponding to.

(Embodiment 6) FIG. 16 shows Embodiment 6 of the present invention, in which two modes are switched between a normal mode and a high image quality mode as in Embodiment 5 above. The driving frequency for one-dot recording is different from that of the fifth embodiment.

That is, in the fifth embodiment, the normal mode is the same as that of the fifth embodiment, and the time required for one dot recording is T1. In the high-quality mode, one-pass printing is performed, and the time required for one-dot printing is T2. In the high-quality mode, the selection circuit 31 outputs two types of first and second drive pulses P1, When P2 is input to the actuator 10, the time from the start of the rise of the first first drive pulse P1 to the start of the rise of the second second drive pulse P2 is T3, T2 <2 × T1, and T3 <T1
The second drive pulse P2 rises in a state in which the pressure chamber 4 is not completely filled with ink after the rise of the first drive pulse P1 (a state in which the ink is not filled during refilling). .

As described above, when the second drive pulse P2 is started in a state where the ink is not completely filled in the pressure chamber 4, the ejection amount of the large ink droplet ejected by the second drive pulse P2 becomes small. However, since the ejection amount is determined by T3, the total amount with small ink droplets can be fixed by fixing T, and does not vary from dot to dot in the high image quality mode. In addition, by doing so, the recording speed in the high image quality mode can be improved as much as possible. On the other hand, by setting the time T1 required for one-dot recording in the normal mode so that refilling can be performed in time, it is possible to prevent variations between dots in the normal mode.

(Embodiment 7) FIG. 17 shows Embodiment 7 of the present invention (the same parts as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted). Small ink droplets and large ink droplets ejected from are accelerated by an electrostatic field.

That is, in the seventh embodiment, the opposing electrode 47 is provided so as to oppose the ink jet head with the recording paper interposed therebetween, and between the ink in the pressure chamber 4 of the ink jet head 1 and the opposing electrode 47. A power supply 48 is provided as voltage applying means for applying a voltage. The positive terminal of the power supply 48 is connected to the partition wall 7 of the ink jet head 1 in a grounded state, while the negative terminal is connected to the counter electrode 47. It is configured such that a high voltage of the order is applied. The voltage of the power supply 48 is variable, and is configured so that the voltage applied between the ink in the pressure chamber 4 of the inkjet head 1 and the counter electrode 47 can be changed.

Therefore, in the seventh embodiment, an electrostatic field is applied between the ink jet head 1 and the counter electrode 47, and a positive charge is induced in the ink. The droplet flies toward the recording paper 41 while being accelerated by the electrostatic field. As a result, the ejection speed of both ink droplets can be increased, and in particular, the flying stability of small ink droplets having a small ejection amount can be improved.

Further, even if the viscosity of the ink changes due to the change of the environment such as the temperature and the ejection speed of both ink droplets changes, the voltage is applied between the ink in the pressure chamber 4 and the counter electrode 47. By appropriately changing the voltage, the ejection speed of both ink droplets can be stabilized.

In the seventh embodiment as well, three or more ink droplets having different discharge amounts may be discharged from the same nozzle 2.

(Embodiment 8) FIG. 18 shows Embodiment 8 of the present invention, in which small ink droplets and large ink droplets are respectively ejected from different nozzles 2 and merged at substantially the same position on the recording paper 41. It is like that.

That is, in the eighth embodiment, the first and second nozzles 2a and 2b are provided so as to be arranged in the main scanning direction (the horizontal direction in FIG. 18: X direction), and the ink jet head 1 is moved in the main scanning direction. While discharging only the small ink droplet (first ink droplet) from the first nozzle 2a, and discharging only the large ink droplet (second ink droplet) from the second nozzle 2b. Ink drops and recording paper 4
It is configured such that one dot is recorded with both ink droplets by combining at substantially the same position on one. That is, only the first drive pulse P1 is input to the actuator 10 corresponding to the first nozzle 2a side, while only the second drive pulse P2 is input to the actuator 10 corresponding to the second nozzle 2b side. Is entered. Then, the ejection speed of the small ink droplet and the large ink droplet is set so that the flight lines of the small ink droplet and the large ink droplet intersect on the recording paper 41.
The rising start timing of the second drive pulses P1 and P2 is set in advance.

Therefore, in the eighth embodiment, the small ink droplet and the large ink droplet are ejected separately from the first and second nozzles 2a and 2b. The ejection timing, ejection amount, and ejection speed of each ink droplet can be easily controlled.
Therefore, both ink droplets can be easily combined at substantially the same position on the recording paper 41.

In the eighth embodiment, two first and second nozzles 2a and 2b are provided so as to be arranged in the main scanning direction, and a small ink droplet is discharged from the first nozzle 2a to the second nozzle 2b. However, three or more nozzles 2 are provided so as to be arranged in the main scanning direction, and three or more ink droplets having different discharge amounts are discharged from each nozzle 2. Alternatively, all the ink droplets may be combined at substantially the same position on the recording paper 41.

In each of the first to eighth embodiments, the inkjet head 1 is moved in the main scanning direction. However, in the case of a line head in which the nozzles 2 of the inkjet head 1 are provided over the entire main scanning direction. Does not move the inkjet head 1 in the main scanning direction. In this case, when the recording paper 41 is being conveyed in the sub-scanning direction by the conveyance motor 26 and the conveyance rollers 42, the small ink droplets and the large ink The droplets may be ejected and united at substantially the same position on the recording paper 41. Therefore, in this case, the transport motor 26 and the transport roller 42 constitute a relative moving unit that relatively moves the inkjet head 1 and the recording paper 41.

Further, the pressure applying means is not limited to the actuator 10 having the piezoelectric element 13, but may be constituted by a heating element which generates bubbles for applying pressure to the pressure chamber 4 by heating ink. Good.

[0087]

As described above, according to the first or twelfth aspect,
According to the invention, when a plurality of types of drive pulses of the drive signal are input to the pressure applying means, a plurality of ink droplets are ejected in ascending order of the ejection amount, and the ejected ink droplets are placed on a recording paper. By combining one dot with a plurality of ink droplets by combining them at substantially the same position, it is possible to eliminate the relative positional deviation between adjacent dots and easily perform gradation recording with good image quality.

According to the second or thirteenth aspect of the present invention, when a plurality of types of drive pulses of the drive signal are inputted to the pressure applying means, a plurality of ink droplets are ejected in descending order of the ejection amount, and the plurality of ejected ink droplets are discharged. Ink droplets are combined at substantially the same position on the recording paper to record one dot with a plurality of ink droplets, thereby preventing the occurrence of satellites at the time of discharging large ink droplets and reducing the size of small ink droplets. The flight stability of the ink droplet can be improved.

According to the third aspect of the present invention, by the power supply means, the one corresponding to the ink droplet having the maximum ejection amount in the drive signal is obtained.
A normal mode in which only one type of driving pulse is input to the pressure applying unit to perform one-pass printing, and one or more types of driving pulses of the driving signal selected by the energizing unit as the pressure applying unit. Mode switching means for switching between at least two modes, that is, a high-quality mode configured to perform two-pass printing so that the drive frequency for one-dot printing is １ ／ of the normal mode described above. By doing so, in the high image quality mode, it is possible to further improve the image quality by two-pass printing while maintaining the printing speed to the maximum, and to keep the carriage speed constant regardless of the mode. .

According to the fourth aspect of the present invention, there is provided a mode switching means for switching between at least two modes of a normal mode and a high image quality mode, wherein the time required for one dot recording in the normal mode is T1, and one dot recording in the high image quality mode is performed. T2, when two types of drive pulses of the drive signal are input to the pressure applying means by the energizing means in the high image quality mode, the rise of the second drive pulse from the start of the rise of the first drive pulse Assuming that the time until the start is T3, T2 <2 × T1 and T3 <
T1 is set so that the second drive pulse rises after the first drive pulse rises in a state where the pressure chamber is not completely filled with ink after the rise of the first drive pulse. It can be improved as much as possible.

According to the fifth aspect of the present invention, when the ink meniscus at the tip of the nozzle projects toward the ejection side from the initial position after the first ink droplet is ejected by the first drive pulse, By driving the second drive pulse to eject the second ink droplet,
The dynamic range can be expanded while improving the recording speed.

According to the sixth aspect of the invention, since the rising start interval between a plurality of types of driving pulses in the driving signal can be changed, the viscosity of the ink and the like due to a change in environment such as temperature can be reduced. Even if the ejection amount or ejection speed of the ink droplet changes, the ink droplet can land at an accurate position.

According to the seventh aspect of the present invention, since the pressure applying means has the vibrating plate provided in the pressure chamber and the piezoelectric element for vibrating the vibrating plate, the discharge amount of the ink droplet and the discharge A pressure applying means that can easily control the speed can be easily obtained.

According to the eighth aspect of the present invention, in the driving signal, the driving pulse for discharging at least the ink droplet having the minimum discharge amount is a voltage drop that falls from the intermediate potential between the minimum potential and the maximum potential to the minimum potential. Waveform, a minimum potential maintenance waveform for maintaining the minimum potential, a potential rising waveform rising from the minimum potential to the maximum potential, a maximum potential maintenance waveform for maintaining the maximum potential, and an intermediate potential return for returning from the maximum potential to the above intermediate potential By having the waveform, the flying stability of the ink droplet with the smallest ejection amount can be improved.

According to the ninth aspect of the present invention, a voltage is applied between the opposing electrode, which is disposed to oppose the ink jet head with the recording paper interposed therebetween, and the ink in the pressure chamber of the ink jet head and the opposing electrode. With this configuration, the flying stability of an ink droplet having a small ejection amount can be improved.

According to the tenth aspect of the present invention, the voltage applied between the ink in the pressure chamber of the ink jet head and the counter electrode can be changed by the voltage applying means. Even if the environment changes,
The ejection speed of the ink droplet can be stabilized.

According to the eleventh aspect of the present invention, at least the first and second nozzles among the plurality of nozzles are provided so as to be arranged in the direction of relative movement between the ink jet head and the recording paper by the relative moving means. No. 1 from nozzle
While ejecting a second ink droplet having a larger ejection amount than the first ink droplet from the second nozzle and ejecting the second ink droplet at substantially the same position on the recording paper as the first ink droplet. By combining and recording one dot with a plurality of ink droplets, the discharge timing, discharge amount, discharge speed, etc. of each ink droplet can be controlled more easily than in the first and second aspects of the invention. The first and second ink droplets can be easily combined at substantially the same position on the recording paper.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an ink jet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a partial plan view of the inkjet head.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a partial sectional view near an actuator.

FIG. 5 is a sectional view taken along line BB of FIG. 2;

FIG. 6 is a block diagram illustrating a configuration of a driving device.

FIG. 7 is a waveform diagram showing a drive signal.

FIG. 8 is a schematic diagram showing the relationship between the flight paths of a small ink droplet and a large ink droplet.

FIG. 9 is a diagram corresponding to FIG. 7, showing the second embodiment.

FIG. 10 is a waveform diagram of a drive signal showing a relationship with an ink meniscus position in the third embodiment.

FIG. 11 is an enlarged sectional view of a nozzle portion showing a change in an ink meniscus.

FIG. 12 is a diagram corresponding to FIG. 7, showing the fourth embodiment.

FIG. 13 is a diagram corresponding to FIG. 6, showing a fifth embodiment.

FIG. 14 is a waveform chart showing a normal mode.

FIG. 15 is a schematic diagram showing a two-pass printing method.

FIG. 16 is a diagram corresponding to FIG. 7, showing the sixth embodiment.

FIG. 17 is a view corresponding to FIG. 1 showing a seventh embodiment.

FIG. 18 is a schematic diagram illustrating first and second nozzles of an inkjet head according to an eighth embodiment.

[Explanation of symbols]

 Reference Signs List 1 inkjet head 2 nozzle 4 pressure chamber 10 actuator (pressure applying means) 11 diaphragm 13 piezoelectric element 16 carriage (relative moving means) 17 carriage shaft (relative moving means) 28 carriage motor (relative moving means) 30 drive signal generating circuit ( Drive signal generating means) 31 selection circuit (energizing means) 35 mode changeover switch (mode switching means) 41 recording paper 45 ink meniscus 47 counter electrode 48 power supply (voltage applying means) P1 first drive pulse P2 second drive pulse P11 Voltage drop waveform P12 Minimum potential sustain waveform P13 Potential rise waveform P14 Maximum potential sustain waveform P15 Intermediate potential return waveform

Continuation of the front page (72) Inventor Akira Fukano 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 2C057 AF23 AF30 AF39 AG12 AG44 AM03 AM15 AM18 AM21 AR16 BA04 BA14 CA04

Claims (13)

[Claims] An ink jet head having a pressure chamber for storing ink, a nozzle communicating with the pressure chamber, and a pressure applying means for applying pressure to the pressure chamber to eject ink droplets from the nozzle; A relative moving means for relatively moving the inkjet head and the recording paper; and a drive signal for generating a drive signal having a plurality of types of drive pulses for respectively ejecting a plurality of ink droplets having different ejection amounts from the nozzles of the inkjet head. Generating means; and applying one or more types of drive pulses of the drive signal generated by the drive signal generating means when the inkjet head and the recording paper are relatively moved by the relative moving means. And an energizing means for selectively inputting to the means and operating the pressure applying means. In the recording apparatus, when a plurality of types of drive pulses of a drive signal are input to the pressure applying unit by the energizing unit, a plurality of ink droplets are ejected in ascending order of their ejection amount, and the ejected ink droplets are connected to each other. Are combined at substantially the same position on the recording paper to record one dot with a plurality of ink droplets. 2. An ink jet head comprising: a pressure chamber for accommodating ink; a nozzle communicating with the pressure chamber; and pressure applying means for applying pressure to the pressure chamber to eject ink droplets from the nozzle. A relative moving means for relatively moving the inkjet head and the recording paper; and a drive signal for generating a drive signal having a plurality of types of drive pulses for respectively ejecting a plurality of ink droplets having different ejection amounts from the nozzles of the inkjet head. Generating means; and applying one or more types of drive pulses of the drive signal generated by the drive signal generating means when the inkjet head and the recording paper are relatively moved by the relative moving means. And an energizing means for selectively inputting to the means and operating the pressure applying means. In the recording apparatus, when a plurality of types of drive pulses of a drive signal are input to the pressure applying unit by the energizing unit, a plurality of ink droplets are ejected in descending order of ejection amount, and the ejected ink droplets are connected to each other. Are combined at substantially the same position on the recording paper to record one dot with a plurality of ink droplets. 3. The ink-jet recording apparatus according to claim 1, wherein only one kind of driving pulse corresponding to the ink droplet having the largest ejection amount in the driving signal is input to the pressure applying means by the energizing means, thereby performing one-pass printing. And the drive frequency for one dot recording is selectively input to the pressure applying means by the energizing means, and the driving frequency for one dot recording is set in the normal mode. An ink jet printing apparatus comprising: mode switching means for switching at least two of a high image quality mode and a high image quality mode configured to perform two-pass printing so that the printing is performed in half. 4. The ink jet recording apparatus according to claim 1, wherein the drive signal has two types of drive pulses, and one type of drive corresponding to an ink droplet having a large ejection amount in the drive signal by a current supply unit. A normal mode in which only a pulse is input to the pressure applying means, and three gradations by selectively inputting any one or two types of driving signals of the driving signal to the pressure applying means by the energizing means. A mode switching means for switching between at least two modes, a high image quality mode and a high image quality mode configured to obtain a value.
1. The time required for one dot recording in the high image quality mode is T2. In the high image quality mode, when two types of driving pulses of the driving signal are input to the pressure applying unit by the energizing unit, the first driving pulse The time from the start of the rise to the start of the rise of the second drive pulse is T
3, T2 <2 × T1 and T3 <T1, and the second drive pulse rises in a state where the pressure chamber is not completely filled with ink after the rise of the first drive pulse. An ink jet recording apparatus characterized by being configured as described above. 5. The ink jet recording apparatus according to claim 1, wherein the driving signal includes a first driving pulse for discharging the first ink droplet and a second driving pulse for discharging the first ink droplet. And a second driving pulse for discharging the ink droplets of the ink. After the first ink droplet is discharged by the first driving pulse, the ink meniscus at the tip of the nozzle is discharged to the initial position. Side, the second
An ink jet recording apparatus characterized in that the drive pulse is raised to eject the second ink droplet. 6. The ink jet recording apparatus according to claim 1, wherein a rising start interval between a plurality of types of driving pulses in the driving signal can be changed. apparatus. 7. The ink jet recording apparatus according to claim 1, wherein the pressure applying means has a vibration plate provided in the pressure chamber and a piezoelectric element for vibrating the vibration plate. Inkjet recording device. 8. The ink jet recording apparatus according to claim 7, wherein a drive pulse for ejecting an ink droplet having a minimum ejection amount in the drive signal ranges from an intermediate potential between the minimum potential and the maximum potential to a minimum potential. A falling voltage waveform, a minimum potential maintaining waveform that maintains the minimum potential, a potential rising waveform that increases from the minimum potential to the maximum potential, a maximum potential maintaining waveform that maintains the maximum potential, and returning from the maximum potential to the above intermediate potential And an intermediate potential returning waveform. 9. The ink jet recording apparatus according to claim 1, wherein a counter electrode is disposed so as to oppose the ink jet head with the recording paper interposed therebetween, and ink in a pressure chamber of the ink jet head and the counter electrode. And a voltage applying means for applying a voltage between the two. 10. The ink jet recording apparatus according to claim 9, wherein a voltage applied between the ink in the pressure chamber of the ink jet head and the counter electrode can be changed by the voltage applying means. An ink jet recording apparatus comprising: 11. A plurality of pressure chambers for accommodating ink, a plurality of nozzles respectively communicating with the pressure chambers, and a plurality of pressure applying means for applying pressure to the pressure chambers and ejecting ink droplets from the nozzles, respectively. And an ink jet head having a relative movement means for relatively moving the ink jet head and the recording paper, and the pressure applying means when the ink jet head and the recording paper are relatively moved by the relative movement means. In at least one of the plurality of nozzles, at least the first and second nozzles are provided so as to be aligned in a relative movement direction between the inkjet head and the recording paper by the relative movement unit, A first ink droplet is ejected from the first nozzle, while a second ink droplet is ejected from the second nozzle. A second ink droplet having a larger ejection amount than one ink droplet is ejected, and is combined with the first ink droplet at substantially the same position on the recording paper to record one dot with a plurality of ink droplets. An ink jet recording apparatus, comprising: 12. An ink jet head having a pressure chamber for accommodating ink, a nozzle communicating with the pressure chamber, and pressure applying means for applying pressure to the pressure chamber to eject ink droplets from the nozzle. Generating a drive signal having a plurality of types of drive pulses for respectively ejecting a plurality of ink droplets having different ejection amounts from the nozzles of the inkjet head, while relatively moving the inkjet head and the recording paper, An ink jet recording method for selectively inputting one or more types of drive pulses of a drive signal to the pressure application unit and operating the pressure application unit, wherein the plurality of types of drive pulses of the drive signal are applied to the pressure application unit. Means for ejecting a plurality of ink droplets in ascending order of ejection amount, and An ink jet recording method comprising: combining a plurality of ink droplets at substantially the same position on the recording paper to record one dot with a plurality of ink droplets. 13. An ink jet head having a pressure chamber for accommodating ink, a nozzle communicating with the pressure chamber, and pressure applying means for applying pressure to the pressure chamber to eject ink droplets from the nozzle. Generating a drive signal having a plurality of types of drive pulses for respectively ejecting a plurality of ink droplets having different ejection amounts from the nozzles of the inkjet head, while relatively moving the inkjet head and the recording paper, An ink jet recording method for selectively inputting one or more types of drive pulses of a drive signal to the pressure application unit and operating the pressure application unit, wherein the plurality of types of drive pulses of the drive signal are applied to the pressure application unit. Means for ejecting a plurality of ink droplets in descending order of their ejection amount, and An ink jet recording method comprising: combining a plurality of ink droplets at substantially the same position on the recording paper to record one dot with a plurality of ink droplets.