JP2004098669A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a decrease in printing speed while preventing generation of white streaks extending in a relative movement direction on a printing medium in printing on a printing medium by an ink jet printing apparatus.
An ink jet recording apparatus includes an ink jet head, a reference pulse generation circuit, and a switch circuit. The reference pulse generation circuit is a circuit that generates a first reference pulse P4a, which is a source for generating a drive pulse, at a predetermined cycle. The preliminary pulse P1 is for vibrating the meniscus of the ink at the tip of the nozzle. The ejection pulse P2 is for ejecting ink droplets from the nozzles. The switch circuit selectively inputs the preliminary pulse P1 and the ejection pulse P2 generated by the reference pulse generation circuit to each piezoelectric actuator.
[Selection] Fig. 8

Description

The present invention relates to an ink jet recording apparatus.

イ ン ク ジ ェ ッ ト Conventionally, there has been known an ink jet recording apparatus that performs recording by utilizing a piezoelectric effect of a piezoelectric body.

An ink jet recording apparatus of this type includes a head body in which a nozzle and a pressure chamber communicating with the nozzle and containing ink are formed, and a pressure chamber configured to eject ink droplets from the nozzle by a piezoelectric effect of a piezoelectric body. Inkjet head having a piezoelectric actuator for applying pressure to the ink, drive signal supply means for supplying a drive signal to the piezoelectric actuator, and relative movement of the inkjet head and the recording paper while ejecting ink droplets from the nozzles Relative movement means for causing The drive signal supply means supplies a drive signal when the inkjet head and the recording paper are relatively moving by the relative movement means. The piezoelectric actuator operates in response to a drive signal, and ejects ink droplets from nozzles. The ejected ink droplet lands on the recording paper to form an ink dot. A predetermined image is formed on the recording paper by arranging a large number of the ink dots on the recording paper.

By the way, when printing is performed using an inkjet head in which a plurality of nozzles are formed in the sub-scanning direction Y (a direction orthogonal to the relative movement direction), as shown in FIG. Alternatively, the landing positions of the ink dots in the sub-scanning direction Y may vary. At this time, white streaks 101 extending in the main scanning direction X (the relative movement direction) are generated on the recording paper, resulting in a deterioration in image quality.

Therefore, in order to solve the above problem, N-pass printing has been conventionally performed in which the same line is printed by scanning the same line N times in the main scanning direction X (N is a natural number of 2 or more). For example, in the case of two-pass printing, as shown in FIG. 29, printing is performed at every other ink dot in the first pass (first scan) when the ink jet head is moved in the main scanning direction X (black dot ink dot). In the second pass (second scan), printing is performed so as to fill the gap (white circle ink dots). At this time, the second ink dot from the top of the first pass and the first ink dot from the top of the second pass are arranged in the main scanning direction X. Accordingly, it is possible to prevent white streaks extending in the main scanning direction X from being generated on the recording paper.

However, in N-pass printing, the same line must be scanned N times, resulting in a decrease in printing speed.

The present invention has been made in view of such a point, and an object of the present invention is to prevent the occurrence of white streaks extending in a relative movement direction on a recording medium in recording on the recording medium by an ink jet recording apparatus. It is another object of the present invention to provide a technique for preventing a reduction in recording speed.

The ink jet recording apparatus according to the present invention is a head body in which a plurality of nozzles and a plurality of pressure chambers communicating with the respective nozzles and containing ink are formed, and a pressure is applied to the ink in each of the pressure chambers. A plurality of pressure applying means for ejecting ink droplets from each of the nozzles to the recording medium, and a drive pulse supply means for supplying a drive pulse for driving each of the pressure applying means to each of the pressure applying means. The nozzle includes at least a first nozzle and a second nozzle arranged in a direction perpendicular to a relative movement perpendicular to a direction relative to the recording medium at the time of ink ejection; A preliminary pulse for vibrating the meniscus of the ink at the tip of the nozzle and a discharge pulse for discharging the ink droplet from the nozzle are sequentially arranged. The first driving pulse is configured to selectively supply a driving pulse and a second driving pulse including the ejection pulse, and the first driving pulse is supplied to a pressure applying unit corresponding to the first nozzle, while the second nozzle is supplied. The second driving pulse is supplied to the pressure applying means corresponding to the above.

{Circle around (2)] By supplying a preliminary pulse to the pressure applying means by the driving pulse supply means, the ink meniscus at the tip of the nozzle vibrates, and the state of the ink meniscus changes. Therefore, the ejection amount and the ejection direction of the ink droplet ejected by supplying the ejection pulse differ depending on the presence or absence of the preliminary pulse. Therefore, by supplying the first drive pulse, one or both of the diameter and the landing position of the ink dot can be changed as compared with the case where the second drive pulse is supplied. Therefore, by supplying the first driving pulse to the pressure applying means corresponding to the first nozzle, the diameter and the landing position of the ink dot can be corrected to a desired state, and the recording medium due to a failure of the ink jet recording apparatus or the like can be corrected. It is possible to prevent the occurrence of white streaks extending in the relative movement direction above. Further, since it is not necessary to perform N-pass printing as in the related art, the printing speed does not decrease. As described above, according to the present invention, it is possible to prevent a decrease in recording speed while preventing the occurrence of white streaks extending in the relative movement direction on the recording medium.

By the way, when the first drive pulse is supplied to the pressure applying means by the drive pulse supply means, one or both of the diameter and the landing position of the ink dot changes. At this time, the ejection speed of the ink droplet may change. Thereby, the landing position in the relative movement direction of the ink dots moves. As a result, image unevenness extending in the direction perpendicular to the relative movement on the recording medium may occur.

According to the present invention, since the drive pulse supply unit supplies the second drive pulse to the pressure applying unit corresponding to the second nozzle, the ejection speed of the ink droplet ejected from the second nozzle does not change. Therefore, the landing position in the relative movement direction of the ink dot corresponding to the second nozzle does not move. Therefore, according to the present invention, it is possible to prevent the occurrence of image unevenness extending in the direction perpendicular to the relative movement on the recording medium.

The ink jet recording apparatus according to the present invention is a head body in which a plurality of nozzles and a plurality of pressure chambers communicating with the respective nozzles and containing ink are formed, and a pressure is applied to the ink in each of the pressure chambers. A plurality of pressure applying means for ejecting ink droplets from each of the nozzles to the recording medium, and a drive pulse supply means for supplying a drive pulse for driving each of the pressure applying means to each of the pressure applying means. The nozzle includes a plurality of nozzles arranged in a relative movement orthogonal direction orthogonal to a direction of relative movement with respect to the recording medium at the time of ink ejection, and the driving pulse supply unit controls an amount of ink at a tip end of the nozzle. A first drive pulse in which a preliminary pulse for vibrating the meniscus and a discharge pulse for discharging an ink droplet from the nozzle are arranged in order; And a second drive pulse composed of pulses. The first drive pulse is supplied to a pressure applying unit corresponding to at least one of the plurality of nozzles during a predetermined printing cycle. While supplying the second drive pulse during a printing cycle different from the predetermined printing cycle.

{Circle around (2)] By supplying a preliminary pulse to the pressure applying means by the driving pulse supply means, the ink meniscus at the tip of the nozzle vibrates, and the state of the ink meniscus changes. Therefore, the ejection amount and the ejection direction of the ink droplet ejected by supplying the ejection pulse differ depending on the presence or absence of the preliminary pulse. Therefore, by supplying the first drive pulse, one or both of the diameter and the landing position of the ink dot can be changed as compared with the case where the second drive pulse is supplied. Therefore, by supplying the first driving pulse to the pressure applying means during a predetermined printing cycle and supplying the second driving pulse during a printing cycle different from the predetermined printing cycle, the diameter of the ink dot and the landing position Can be corrected to a desired state, and the occurrence of white streaks extending in the relative movement direction on the recording medium due to a malfunction of the ink jet recording apparatus or the like can be prevented. Further, since it is not necessary to perform N-pass printing as in the related art, the printing speed does not decrease. As described above, according to the present invention, it is possible to prevent a decrease in recording speed while preventing the occurrence of white streaks extending in the relative movement direction on the recording medium.

The ink jet recording apparatus according to the present invention further includes a reference pulse generating means for generating a reference pulse including a first reference pulse in which the preliminary pulse and the ejection pulse are arranged in order and a second reference pulse including the ejection pulse. The drive pulse supply means supplies the pressure pulse generating means with the reference pulse generated by the reference pulse generation means as the drive pulse.

Accordingly, since the drive pulse supply unit supplies the reference pulse as a drive pulse to the pressure applying unit, a unit for generating a drive pulse from the preliminary pulse and the ejection pulse becomes unnecessary in the drive pulse supply unit. . Therefore, according to the present invention, the configuration of the drive pulse supply unit can be simplified.

(4) In the ink jet recording apparatus according to the present invention, the waveform of the ejection pulse of the first reference pulse is different from the waveform of the ejection pulse of the second reference pulse.

When one or both of the diameter and the landing position of the ink dot is changed by supplying the first reference pulse to the pressure applying means by the driving pulse supply means, one or both of the ejection amount and the ejection speed of the ink droplet change. May be. As a result, image unevenness may occur on the recording medium.

Here, according to the present invention, the difference in the ejection amount between the ink droplet by supplying the first reference pulse and the ink droplet by supplying the second reference pulse, and the ink droplet by supplying the first reference pulse In order to correct one or both of the differences in the ejection speed between the ink droplet and the ink droplet by supplying the second reference pulse and the second reference pulse, the waveform of the ejection pulse of the first reference pulse and the waveform of the ejection pulse of the second reference pulse are changed. different. Therefore, it is possible to equalize one or both of the ejection amount and the ejection speed of the ink droplet. Therefore, according to the present invention, it is possible to prevent the occurrence of image unevenness on the recording medium due to the supply of the first reference pulse.

The ink jet recording apparatus according to the present invention further comprises the first first drive pulse and the first first drive pulse when the drive pulse supply unit sequentially supplies at least three first, second, and third first drive pulses. An interval between the second first drive pulse and the interval between the second first drive pulse and the third first drive pulse is made different.

As described above, when the first driving pulse is supplied to the pressure applying unit by the driving pulse supplying unit, one or both of the diameter and the landing position of the ink dot changes. At this time, the ejection speed of the ink droplet may change. Thereby, the landing position in the relative movement direction of the ink dots moves. As a result, image unevenness that extends in the direction perpendicular to the relative movement on the recording medium occurs. Here, the interval between the first first drive pulse and the second first drive pulse is the same as the interval between the second first drive pulse and the third first drive pulse. Then, image unevenness extending in the direction perpendicular to the relative movement on the recording medium occurs at the same interval.

Here, according to the present invention, the interval between the first first drive pulse and the second first drive pulse and the interval between the second first drive pulse and the third first drive pulse are determined. Since the interval is different, image unevenness extending in the direction perpendicular to the relative movement on the recording medium occurs at different intervals. Therefore, according to the present invention, it is possible to prevent image unevenness extending in the direction perpendicular to the relative movement on the recording medium from occurring at the same interval.

The ink jet recording apparatus according to the present invention is a head body in which a plurality of nozzles and a plurality of pressure chambers communicating with the respective nozzles and containing ink are formed, and a pressure is applied to the ink in each of the pressure chambers. A plurality of pressure applying means for ejecting ink droplets from each of the nozzles to the recording medium, and a drive pulse supply means for supplying a drive pulse for driving each of the pressure applying means to each of the pressure applying means. The nozzle includes at least a first nozzle and a second nozzle arranged in a direction perpendicular to the direction of relative movement with respect to the recording medium when ejecting ink, and corresponds to the first and second nozzles. When the same drive pulse is supplied to the two pressure applying means, the ink droplet ejected from the second nozzle has a predetermined reference diameter and a reference landing position on the recording medium. While forming an ink dot, the ink droplet ejected from the first nozzle forms an ink dot on the recording medium having a diameter different from a predetermined reference diameter and / or a landing position shifted from the reference landing position. In the ink jet recording apparatus, the driving pulse supply unit includes a preliminary pulse for oscillating a meniscus of ink at a tip of the nozzle and an ejection pulse for ejecting an ink droplet from the nozzle in order. A first drive pulse and a second drive pulse composed of the ejection pulse are selectively supplied. The first drive pulse is supplied to a pressure applying unit corresponding to the first nozzle, while the first drive pulse is supplied to the pressure application unit. The second driving pulse is supplied to the pressure applying means corresponding to the second nozzle.

{Circle around (2)] By supplying a preliminary pulse to the pressure applying means by the driving pulse supply means, the ink meniscus at the tip of the nozzle vibrates, and the state of the ink meniscus changes. Therefore, the ejection amount and the ejection direction of the ink droplet ejected by supplying the ejection pulse differ depending on the presence or absence of the preliminary pulse. Therefore, by supplying the first drive pulse, one or both of the diameter and the landing position of the ink dot can be changed as compared with the case where the second drive pulse is supplied. Therefore, even if the ink dot corresponding to the first nozzle has one or both of a diameter different from the predetermined reference diameter and a landing position deviated from the reference landing position due to a failure of the ink jet recording apparatus, the difference is corrected. By changing one or both of the diameter and the landing position of the ink dot corresponding to the first nozzle as described above, it is possible to prevent the generation of white streaks extending in the relative movement direction on the recording medium. Further, since it is not necessary to perform N-pass printing as in the related art, the printing speed does not decrease. As described above, according to the present invention, it is possible to prevent a decrease in recording speed while preventing the occurrence of white streaks extending in the relative movement direction on the recording medium.

The ink jet recording apparatus according to the present invention further comprises reference pulse generating means for generating a reference pulse for driving each of the pressure applying means, wherein the reference pulse comprises the preliminary pulse and the ejection pulse, The pulse supply means generates one of the first and second drive pulses from the preliminary pulse and the ejection pulse generated by the reference pulse generation means, and supplies one of the first and second drive pulses to the pressure applying means.

に よ り Thereby, the drive pulse supply means generates one of the first and second drive pulses from the preliminary pulse and the ejection pulse generated by the reference pulse generation means. Therefore, according to the present invention, various drive pulses can be generated.

In the ink jet recording apparatus according to the present invention, the amplitude of the preliminary pulse and the amplitude of the ejection pulse are the same, and the pulse width of the preliminary pulse is 1/40 to 1/5 of the Helmholtz period of the head.

(4) Since the amplitude of the preliminary pulse and the amplitude of the ejection pulse are the same, the preliminary pulse and the ejection pulse can be generated by performing ON / OFF switching operation at a constant voltage. Therefore, according to the present invention, the preliminary pulse and the ejection pulse can be easily generated.

Further, since the pulse width of the preliminary pulse is 1/40 or more of the Helmholtz period of the head, the ink meniscus at the tip of the nozzle can be vibrated by supplying the preliminary pulse to the pressure applying means by the driving pulse supplying means. . Further, since the pulse width of the preliminary pulse is not more than 1/5 of the Helmholtz period of the head, no ink droplet is ejected from the nozzle even if the preliminary pulse is supplied to the pressure applying means by the driving pulse supplying means. As described above, according to the present invention, by supplying the first driving pulse to the pressure applying unit by the driving pulse supplying unit, one or both of the diameter and the landing position of the ink dot corresponding to the pressure applying unit can be reliably changed. Can be done.

In the inkjet recording apparatus according to the present invention, the interval between the start of the supply of the preliminary pulse and the start of the supply of the ejection pulse in the first drive pulse is twice or less the Helmholtz period of the head. .

Since the interval between the start of the supply of the preliminary pulse and the start of the supply of the ejection pulse is less than twice the Helmholtz period of the head, the supply of the preliminary pulse causes the ink meniscus at the tip of the nozzle to vibrate sufficiently. During this operation, the ejection pulse is supplied. Therefore, according to the present invention, by supplying the first driving pulse to the pressure applying unit by the driving pulse supplying unit, one or both of the diameter and the landing position of the ink dot corresponding to the pressure applying unit are surely changed. be able to.

The inkjet according to the present invention further includes a first ink dot formed by supplying the second driving pulse to the pressure applying unit, and a second ink dot formed by supplying the first driving pulse to the pressure applying unit. Are different from each other in the direction perpendicular to the relative movement.

(4) Thereby, the landing positions in the direction perpendicular to the relative movement between the first ink dot and the second ink dot are different. Therefore, according to the present invention, even if the landing position in the relative movement orthogonal direction of the ink dot is shifted from the predetermined landing position due to a defect of the ink jet recording apparatus or the like, the landing position in the relative movement orthogonal direction of the ink dot is changed. Thus, it is possible to reliably prevent the occurrence of white streaks extending in the relative movement direction on the recording medium.

The ink jet recording apparatus according to the present invention further has a cross section perpendicular to the relative movement direction of the ink meniscus at the tip of the nozzle corresponding to the pressure applying means when the preliminary pulse is supplied to the pressure applying means. , Asymmetric with respect to the axis of the nozzle.

By supplying the preliminary pulse to the pressure applying means by the drive pulse supplying means, the shape of the cross section orthogonal to the relative movement direction of the ink meniscus at the tip of the nozzle corresponding to the pressure applying means is related to the axis of the nozzle. Become asymmetric. Therefore, when the ejection pulse is supplied after the supply of the preliminary pulse, the ink droplet is ejected in a direction shifted from the axis of the nozzle. Therefore, according to the present invention, by supplying the first drive pulse to the pressure applying means corresponding to the nozzle by the drive pulse supply means, the impact position of the ink dot corresponding to the nozzle in the relative movement orthogonal direction can be reliably determined. Can be changed.

In the ink jet recording apparatus according to the present invention, the nozzles arranged in the direction perpendicular to the relative movement are each provided at a position shifted from the center position of the pressure chamber communicating with the nozzle in the direction perpendicular to the relative movement. is there.

With this arrangement, the nozzles arranged in the direction perpendicular to the relative movement are provided at positions deviated from the center position of the pressure chamber communicating with the nozzle in the direction perpendicular to the relative movement. When the preliminary pulse is supplied, the shape of the cross section orthogonal to the relative movement direction of the ink meniscus at the tip of the nozzle corresponding to the pressure applying means is surely asymmetric with respect to the axis of the nozzle. Therefore, according to the present invention, by supplying the first drive pulse to the pressure applying means by the drive pulse supply means, it is possible to reliably change the landing position of the ink dot in the direction perpendicular to the relative movement.

In the ink jet recording apparatus according to the present invention, the cross-sectional shapes of the nozzles arranged in the direction perpendicular to the relative movement are orthogonal to the axis of the nozzle.

Thereby, since the cross-sectional shape of the nozzles arranged in the direction of relative movement orthogonal to the direction of relative movement becomes asymmetric with respect to the axis of the nozzle, when a preliminary pulse is supplied to the pressure applying means by the driving pulse supply means, The shape of the cross section orthogonal to the direction of relative movement of the ink meniscus at the time is surely asymmetric with respect to the axis of the nozzle. Therefore, according to the present invention, by supplying the first drive pulse to the pressure applying means by the drive pulse supply means, it is possible to reliably change the landing position of the ink dot in the direction perpendicular to the relative movement.

In the ink jet recording apparatus according to the present invention, the distance between the center position of the first ink dot and the center position of the second ink dot in the direction perpendicular to the relative movement is で or less of the pitch of the ink dots. There is something.

Thus, according to the present invention, the distance in the direction perpendicular to the relative movement between the center position of the first ink dot and the center position of the second ink dot is １ ／ or less of the pitch of the ink dots. The distance between the ink dot and the second ink dot can be kept small. Therefore, according to the present invention, the image quality can be improved.

Further, in the ink jet recording apparatus according to the present invention, the drive pulse supply means may selectively select, as the drive pulse, a third drive pulse including the preliminary pulse in addition to the first drive pulse and the second drive pulse. Supply.

Thereby, the drive pulse supply means selectively supplies the third drive pulse as the drive pulse. Therefore, according to the present invention, by supplying the third drive pulse, it is possible to prevent the ink in the pressure chamber from drying and increasing the viscosity.

イ ン ク ジ ェ ッ ト Further, in the ink jet recording apparatus according to the present invention, the pressure applying means comprises a piezoelectric element.

(4) Since the pressure applying means is made of a piezoelectric element, the control of contraction and expansion of the pressure chamber is facilitated. Therefore, it is possible to reliably control the diameter and the landing position of the ink dot. Therefore, according to the present invention, the image quality can be improved.

According to the present invention, since the ink meniscus at the tip of the nozzle vibrates by supplying the preliminary pulse to the pressure applying means by the drive pulse supplying means, the ink discharged by supplying the discharge pulse depending on the presence or absence of the preliminary pulse is provided. The ejection amount and ejection direction of the droplet are different. Therefore, by supplying the first drive pulse, one or both of the diameter and the landing position of the ink dot can be changed as compared with the case where the second drive pulse is supplied. Therefore, by supplying the first driving pulse to the pressure applying means corresponding to the first nozzle, the diameter and the landing position of the ink dot can be corrected to a desired state, and the recording medium due to a failure of the ink jet recording apparatus or the like can be corrected. It is possible to prevent the occurrence of white streaks extending in the relative movement direction above. Further, since it is not necessary to perform N-pass printing as in the related art, the printing speed does not decrease. As described above, according to the present invention, it is possible to prevent a decrease in recording speed while preventing the occurrence of white streaks extending in the relative movement direction on the recording medium.

By the way, when the first drive pulse is supplied to the pressure applying means by the drive pulse supply means, one or both of the diameter and the landing position of the ink dot changes. At this time, the ejection speed of the ink droplet may change. Thereby, the landing position in the relative movement direction of the ink dots moves. As a result, image unevenness extending in the direction perpendicular to the relative movement on the recording medium may occur.

According to the present invention, since the drive pulse supply unit supplies the second drive pulse to the pressure applying unit corresponding to the second nozzle, the ejection speed of the ink droplet ejected from the second nozzle does not change. Accordingly, since the landing position in the relative movement direction of the ink dot corresponding to the second nozzle does not move, it is possible to prevent the occurrence of image unevenness extending in the direction perpendicular to the relative movement on the recording medium.

In addition, since the ink meniscus at the tip of the nozzle vibrates by supplying the preliminary pulse to the pressure applying unit by the driving pulse supplying unit, the ejection amount of the ink droplet ejected by supplying the ejection pulse depending on the presence or absence of the preliminary pulse And the discharge direction are different. Therefore, by supplying the first drive pulse, one or both of the diameter and the landing position of the ink dot can be changed as compared with the case where the second drive pulse is supplied. Therefore, the first drive pulse is supplied to at least one of the plurality of pressure applying units arranged in the direction perpendicular to the relative movement during the predetermined printing period, while the first driving pulse is supplied during the printing period different from the predetermined printing period. By supplying the two drive pulses, the diameter and the landing position of the ink dot can be corrected to a desired state, and the occurrence of white streaks extending in the relative movement direction on the recording medium due to a malfunction of the ink jet recording apparatus or the like is prevented. Can be prevented.

In addition, by supplying a preliminary pulse to the pressure applying means by the drive pulse supplying means, the ink meniscus at the tip of the nozzle vibrates. Therefore, by supplying a first driving pulse in which the preliminary pulse and the ejection pulse are arranged in order to the pressure applying means corresponding to the first nozzle, one or both of the diameter and the landing position of the ink dot are changed. Can be. Further, even if the second driving pulse composed of the ejection pulse is supplied to the pressure applying means corresponding to the second nozzle, the diameter and the landing position of the ink dot do not change. Therefore, even if the ink dot corresponding to the first nozzle has one or both of a diameter different from the predetermined reference diameter and a landing position deviated from the reference landing position due to a failure of the ink jet recording apparatus, the difference is corrected. By changing one or both of the diameter and the landing position of the ink dot corresponding to the first nozzle as described above, it is possible to prevent the generation of white streaks extending in the relative movement direction on the recording medium.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, the ink jet recording apparatus according to the present embodiment includes an ink jet head 1 that discharges ink droplets onto a recording paper 41, a carriage 16 that relatively moves the ink jet head 1 and the recording paper 41, and a carriage shaft 17. And a carriage motor 28 (see FIG. 6). The ink jet head 1 is supported and fixed on a carriage 16. The carriage 16 is movably supported by a carriage shaft 17 extending in the main scanning direction X. The carriage 16 is provided with a carriage motor 28. When the carriage motor 28 is driven, the inkjet head 1 and the carriage 16 move along the carriage shaft 17. The recording medium according to the present invention corresponds to the recording paper 41, and the relative movement direction corresponds to the main scanning direction X.

(4) The recording paper 41 is sandwiched between three upper and lower transport rollers 42 which are driven to rotate by the transport motor 26 (see FIG. 6). The recording paper 41 is conveyed in the sub-scanning direction Y orthogonal to the main scanning direction X by rotating the conveyance motor 26. Note that the relative movement orthogonal direction referred to in the present invention corresponds to the sub-scanning direction Y.

As shown in FIGS. 2 to 5, the inkjet head 1 includes a plurality of pressure chambers 4 for storing ink, a plurality of nozzles 2 respectively communicating with the pressure chambers 4, and a pressure chamber 4. A plurality of piezoelectric actuators for discharging ink droplets from the nozzles; The pressure applying means in the present invention is constituted by the piezoelectric actuator 10.

As shown in FIG. 2, the pressure chambers 4 are formed in the ink jet head 1 in a long groove shape extending in the main scanning direction X, and are formed at predetermined intervals in the sub scanning direction Y. In the present embodiment, seven pressure chambers 4 are formed at predetermined intervals in the sub-scanning direction Y, and the seven pressure chambers 4 are first to seventh pressure chambers 4a, 4b, 4c, 4d, 4e, 4f and 4g. At one end (the right end in FIG. 2) of the pressure chamber 4 on the lower surface of the inkjet head 1, nozzles 2 are formed at predetermined intervals in the sub-scanning direction Y. In the present embodiment, the first to seventh nozzles 2a, 2b, 2c, 2d, 2e, 2f, 2g corresponding to the first to seventh pressure chambers 4a, 4b, 4c, 4d, 4e, 4f, 4g, respectively. Is formed. 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 on the lower surface of the inkjet head 1. The other end of the ink supply path 5 is connected to the ink supply chamber 3 extending in the sub-scanning direction Y.

As shown in FIG. 3, the inkjet head 1 includes a nozzle plate 6 in which the nozzles 2 are formed, a partition wall 7 that defines the pressure chamber 4 and the ink supply path 5, and a piezoelectric actuator 10 which are sequentially stacked. It is configured. The nozzle plate 6 is made of a 20 μm thick polyimide plate, and the partition wall 7 is made of a 280 μm thick stainless steel laminate plate. Incidentally, the head main body in the present invention is constituted by the nozzle plate 6 and the partition wall 7.

圧 電 As shown in FIG. 5, the piezoelectric actuators 10 are formed at predetermined intervals in the sub-scanning direction Y. In the present embodiment, the first to seventh pressure chambers 4a, 4b, 4c, 4d, 4e, 4f, 4g correspond to the respective portions (the portions directly above the respective pressure chambers 4). To the seventh piezoelectric actuators 10a, 10b, 10c, 10d, 10e, 10f, 10g. As shown in FIGS. 4 and 5, the piezoelectric actuator 10 includes a vibration plate 11 provided to close the pressure chamber 4, a piezoelectric element 13 for vibrating the vibration plate 11, and an individual electrode 14, which are sequentially stacked. It is configured. 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 made of PZT (lead zirconate titanate) having a thickness of 3 μm, and is provided in a portion corresponding to the pressure chamber 4 (a portion immediately above the pressure chamber 4). The individual electrode 14 is made of Pt having a thickness of 0.1 μm. Note that an insulating plate 15 made of polyimide is provided between the adjacent piezoelectric elements 13 (individual electrodes 14).

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. The drive device 20 controls the drive of a control unit 21 including a CPU, a ROM 22 storing various data processing routines and the like, a RAM 23 storing various data, and the like, and a transport motor 26 and a carriage motor 28. Driver circuits 25 and 27, a motor control circuit 24, a data receiving circuit 29 for receiving print data, a reference pulse generating circuit 30, and a switch circuit 31. The reference pulse generating means in the present invention is constituted by a reference pulse generating circuit 30, and the drive pulse supplying means is constituted by a switch circuit 31.

The reference pulse generation circuit 30 is a circuit that generates a first reference pulse P4a (see FIG. 7), which is a source for generating a drive pulse P3 composed of a preliminary pulse P1 and a discharge pulse P2 described later, at a predetermined cycle. .

As shown in FIG. 7, the first reference pulse P4a has a preliminary pulse P1 and a discharge pulse P2 alternately.

The preliminary pulse P1 is for vibrating the meniscus of the ink at the tip of the nozzle 2. The preliminary pulse P1 has a falling waveform P12 that deforms the piezoelectric actuator 10 so that the pressure chamber 4 expands, and a rising waveform P11 that deforms the piezoelectric actuator 10 so that the pressure chamber 4 contracts, and has a trapezoidal shape. Is formed. When only the preliminary pulse P1 is input to the piezoelectric actuator 10, no ink droplet is ejected from the nozzle 2.

The ejection pulse P2 is a pulse for ejecting an ink droplet from the nozzle 2. The ejection pulse P2 has a falling waveform P22 and a rising waveform P21, and is formed in a trapezoidal shape. Then, the falling waveform P22 is first input to the individual electrode 14 of the piezoelectric actuator 10, whereby the pressure chamber 4 is filled with ink. After that, a rising waveform P21 is input to the piezoelectric actuator 10, whereby an ink droplet is ejected from the nozzle 2.

{Also, the amplitude V1-V2 of the preliminary pulse P1 is smaller than the amplitude V1-V3 of the ejection pulse P2. Note that the preliminary pulse P1 and the ejection pulse P2 are referred to as a pushing waveform.

As shown in FIG. 6, the switch circuit 31 is connected to the individual electrodes 14 of each piezoelectric actuator 10 and has a circuit capable of switching ON / OFF of a transistor or the like. In the present embodiment, the first to seventh switch circuits 31a, 31b, 31c, 31d connected to the individual electrodes 14 of the first to seventh piezoelectric actuators 10a, 10b, 10c, 10d, 10e, 10f, 10g, respectively. , 31e, 31f and 31g are provided. When the inkjet head 1 is moving in the main scanning direction, each switch circuit 31 applies the preliminary pulse P1 and the ejection pulse P2 of the first reference pulse P4a generated by the reference pulse generation circuit 30 to each piezoelectric actuator 10. Input selectively.

Here, what drive pulse P3 is input to each piezoelectric actuator 10 by each switch circuit 31 is arbitrarily determined. In the present embodiment, a first drive pulse P3a described later is input to the second, fourth, and sixth piezoelectric actuators 10b, 10d, 10f. On the other hand, a second drive pulse P3b described later is input to the first, third, fifth, and seventh piezoelectric actuators 10a, 10c, 10e, and 10g.

Specifically, as shown in FIG. 8A, the second, fourth, and sixth switch circuits 31b, 31d, and 31f output the 2N-1th (N is a natural number) spare pulse P1 from the left, respectively. Sometimes, the first drive pulse P3a is generated by turning off the transistor. Then, the second, fourth and sixth switch circuits 31b, 31d and 31f input the first drive pulse P3a to the second, fourth and sixth piezoelectric actuators 10b, 10d and 10f, respectively.

On the other hand, the first, third, fifth and seventh switch circuits 31a, 31c, 31e and 31g each turn off the transistor when the preliminary pulse P1 of the first reference pulse P4a is output, as shown in FIG. 8B. By setting the state, the second drive pulse P3b is generated. The first, third, fifth and seventh switch circuits 31a, 31c, 31e and 31g are respectively connected to the first, third, fifth and seventh piezoelectric actuators 10a, 10c, 10e and 10g by the second. The driving pulse P3b is input. The first drive pulse referred to in the present invention corresponds to the 2N-th preliminary pulse P1 and ejection pulse P2 from the left in the first drive pulse P3a, and the second drive pulse corresponds to the 2N-th from the left in the second drive pulse P3b. Corresponding to the ejection pulse P2.

In this way, each switch circuit 31 selectively supplies a driving pulse composed of the preliminary pulse P1 and the ejection pulse P2 in order and a driving pulse composed of the ejection pulse P2 to each piezoelectric actuator 10. ing.

In the first drive pulse P3a, the interval between the start of the input of the 2Nth preliminary pulse P1 from the left and the start of the input of the 2Nth ejection pulse P2 from the left is twice or less the Helmholtz period of the head. In this case, at the start of the input of the ejection pulse P2, the ink meniscus 45 at the tip of the nozzle 2 is vibrating. In short, at the start of the input of the ejection pulse P2, the ink meniscus 45 is not at a position stabilized after the vibration, that is, at the reference position (the position shown by the solid line in FIG. 9).

(Recording by inkjet recording device)
Next, a description will be given of a process when recording is performed using an ink jet recording apparatus.

First, the recording paper 41 is transported to a desired position by the transport motor 26 and the transport rollers 42. The carriage motor 28 conveys the inkjet head 1 together with the carriage 16 along the carriage shaft 17 from one end (the position X1 in FIG. 1) to the other end (the position X2 in FIG. 1). At the same time, the reference pulse generation circuit 30 generates the first reference pulse P4a at a predetermined cycle. The second, fourth, and sixth switch circuits 31b, 31d, and 31f each receive the first drive pulse P3a. On the other hand, the first, third, fifth and seventh switch circuits 31a, 31c, 31e and 31g each receive the second drive pulse P3b.

At this time, as shown in FIG. 9, when the 2N-th preliminary pulse P1 from the left is input, the ink meniscus 45 at the tip of the second, fourth, and sixth nozzles 2b, 2d, 2f moves from the reference position. As shown by the one-dot chain line, it is largely displaced toward the pressure chamber 4. Then, the nozzle 2 is displaced to the tip end side of the nozzle 2 (opposite the pressure chamber 4 side) as shown by a two-dot chain line as it passes through the reference position. Thereafter, displacement to the pressure chamber 4 side is repeated again. The vibration of the ink meniscus 45 is a damped vibration. Here, at the start of input of the 2N-th ejection pulse P2 from the left, the cross-sectional shape of the ink meniscus 45 orthogonal to the main scanning direction X is related to the axis A of the second, fourth, and sixth nozzles 2b, 2d, 2f, respectively. The landing positions of the 2N-th second, fourth, and sixth ink dots 47b, 47d, and 47f from the left are asymmetric, and the 2N-first second, fourth, and sixth ink dots 47b, 47d, and 2N-th from the left. The first drive pulse P3a is formed so as to move upward (direction Y1) from the landing position of 47f. Therefore, the ejection direction of the ink droplet ejected from the second, fourth, and sixth nozzles 2b, 2d, 2f is changed by the input of the 2Nth ejection pulse P2 from the left. Thereby, as shown in FIG. 10, the landing positions of the 2N-th second, fourth, and sixth ink dots 47b, 47d, and 47f from the left are changed to the 2N-1th second, fourth, and sixth ink dots from the left. The ink dots 47b, 47d, and 47f move toward the Y1 side from the landing positions. In the present embodiment, the positions of the centers of the 2N-th second, fourth, and sixth ink dots 47b, 47d, and 47f from the left are respectively the 2N-1st second, fourth, and sixth ink dots from the left. The ink dots 47 are moved by half the pitch of the ink dots 47 in the Y1 direction from the center positions of 47b, 47d, and 47f. The length of the movement is preferably 1/40 to 1/2 of the pitch of the ink dots 47. Note that the first ink dot in the present invention corresponds to the 2N-1st second, fourth, and sixth ink dots 47b, 47d, and 47f from the left, and the second ink dot is the 2Nth ink dot from the left. 2, and correspond to the fourth and sixth ink dots 47b, 47d, 47f.

As described above, white stripes extending in the main scanning direction X are prevented from being generated between the first ink dot 47a and the second ink dot 47b and between the fifth ink dot 47e and the sixth ink dot 47f. be able to.

According to the present embodiment, the second, fourth, and sixth nozzles 2b, 2d, 2f are input by the second, fourth, and sixth switch circuits 31b, 31d, and 31f receiving the 2Nth preliminary pulse P1 from the left. Since the ink meniscus 45 at the tip of the ink vibrates, the state of the ink meniscus 45 changes. Therefore, the landing positions of the 2N-th second, fourth, and sixth ink dots 47b, 47d, and 47f from the left correspond to the 2N-1st second, fourth, and sixth ink dots 47b, 47d, and 47f from the left. It moves in the Y1 direction from the landing position. Therefore, white streaks extending in the main scanning direction X between the first ink dot 47a and the second ink dot 47b and between the fifth ink dot 47e and the sixth ink dot 47f on the recording paper 41 can be prevented. Can be prevented. Further, since it is not necessary to perform N-pass printing as in the related art, it is possible to prevent a reduction in printing speed. As described above, it is possible to prevent the occurrence of white streaks extending in the main scanning direction X on the recording paper 41 and to prevent a decrease in the recording speed.

Also, the center positions of the 2N-th second, fourth and sixth ink dots 47b, 47d and 47f from the left are respectively the 2N-1st second, fourth and sixth ink dots 47b, 47d and 47d from the left. In order to move from the center position of 47f toward the Y1 side by a length of の of the pitch of the ink dots 47, the 2Nth second, fourth and sixth ink dots 47b, 47d, and 47f from the left are The distance of the landing position in the sub-scanning direction Y between the 2N-1st second, fourth, and sixth ink dots 47b, 47d, and 47f from the left can be kept small. Therefore, the image quality can be improved.

In the first drive pulse P3a, the interval between the start of the input of the 2Nth preliminary pulse P1 from the left and the start of the input of the 2Nth ejection pulse P2 from the left is not more than twice the Helmholtz period of the head. By inputting the preliminary pulse P1, the ejection pulse P2 is input while the ink meniscus 45 at the tip of the second, fourth and sixth nozzles 2b, 2d, 2f is sufficiently vibrating. Therefore, the landing positions of the 2N-th second, fourth, and sixth ink dots 47b, 47d, and 47f from the left correspond to the 2N-1st second, fourth, and sixth ink dots 47b, 47d, and 47f from the left. It surely moves in the direction of the Y1 side from the landing position.

Further, the first to seventh switch circuits 31a, 31b, 31c, 31d, 31e, 31f, 31g each use the preliminary pulse P1 and the ejection pulse P2 generated by the reference pulse generation circuit 30 to determine the first and second drive pulses P3a, Generate one of P3b. Therefore, various drive pulses P3 can be generated.

(4) Since the pressure applying means is composed of the piezoelectric actuator 10, control of contraction and expansion of the pressure chamber 4 becomes easy. Therefore, the diameter and landing position of the ink dot 47 can be reliably controlled, so that image quality can be improved.

In the present embodiment, the shape of the cross section of the ink meniscus 45 orthogonal to the main scanning direction X is asymmetric with respect to the axis A of the second nozzle 2b or the like at the start of input of the 2Nth ejection pulse P2 from the left. , The first drive pulse P3a is formed, but not limited to this. For example, at the start of input of the 2N-th ejection pulse P2 from the left, the first drive pulse may be formed such that ink adheres to the tip of the second nozzle 2b or the like. At this time, the landing position of the 2N-th second ink dot 47b and the like from the left moves in the Y1 direction from the landing position of the 2N-1st second ink dot 47b and the like from the left.

Further, in the present embodiment, the landing position of the 2N-th second ink dot 47b from the left and the like is moved toward the Y1 side from the landing position of the 2N-1st second ink dot 47b and the like from the left. Although the first drive pulse P3a is formed, the first drive pulse P3a may be formed so that the landing position of an arbitrary second ink dot 47b or the like moves in the Y1 direction.

Further, in the present embodiment, the landing position of the 2N-th second ink dot 47b from the left and the like is moved toward the Y1 side from the landing position of the 2N-1st second ink dot 47b and the like from the left. Although the first drive pulse P3a is formed, the first drive pulse P3a may be formed so as to move in the Y2 direction.

In the present embodiment, the first and second drive pulses P3a and P3b are configured as described above. However, as long as the first drive pulse P3a includes the preliminary pulse P1 and the ejection pulse P2, the first and second drive pulses P3a and P3b are used. The drive pulses P3a and P3b may be of any type.

(Embodiment 2)
The ink jet recording apparatus according to the present embodiment performs test recording before actually performing recording using the ink jet recording apparatus, and changes the landing position of the ink dot. The configuration is almost the same as that of the ink jet recording apparatus of the first embodiment. Hereinafter, a configuration different from the first embodiment will be described.

By the way, what drive pulse P3 is input to each piezoelectric actuator 10 by each switch circuit 31 is determined in advance based on the result of test recording described later. In the present embodiment, a third drive pulse P3c described later is input to the sixth piezoelectric actuator 10f. On the other hand, the above-described second drive pulse P3b (see FIG. 8B) is input to the first to fifth and seventh piezoelectric actuators 10a, 10b, 10c, 10d, 10e, and 10g. In the present invention, the first nozzle corresponds to the sixth nozzle 2f, and the second nozzle corresponds to the first to fifth and seventh nozzles 2a, 2b, 2c, 2d, 2e, 2g.

Specifically, as shown in FIG. 11, the sixth switch circuit 31f turns on the transistor for one cycle of the first reference pulse P4a, thereby generating the same third drive pulse P3c as the first reference pulse P4a. Generate. Then, the sixth switch circuit 31f inputs the third drive pulse P3c to the sixth piezoelectric actuator 10f.

In this way, each switch circuit 31 selectively supplies a driving pulse composed of the preliminary pulse P1 and the ejection pulse P2 in order and a driving pulse composed of the ejection pulse P2 to each piezoelectric actuator 10. ing.

(Test recording by inkjet recording device)
Next, a description will be given of a test recording process performed before actually performing recording using the ink jet recording apparatus.

First, the recording paper 41 is transported to a desired position by the transport motor 26 and the transport roller 42, and the inkjet head 1 is transported from X1 to X2 along the carriage shaft 17. At the same time, the reference pulse generation circuit 30 generates the first reference pulse P4a at a predetermined cycle. Next, the first to seventh switch circuits 31a, 31b, 31c, 31d, 31e, 31f, 31g respectively generate a second drive pulse P3b from the first reference pulse P4a, and the first to seventh piezoelectric actuators 10a, 10b. , 10c, 10d, 10e, 10f, and 10g, the second drive pulse P3b is input, and ink droplets are ejected from the first to seventh nozzles 2a, 2b, 2c, 2d, 2e, 2f, and 2g of the inkjet head 1. Let it. As a result, as shown in FIG. 12, the ink droplets ejected from the first to seventh nozzles 2a, 2b, 2c, 2d, 2e, 2f, and 2g land on the recording paper 41, respectively. The seventh ink dots 47a, 47b, 47c, 47d, 47e, 47f, 47g are formed. As described above, a test print image for one scan of the inkjet head 1 is recorded on the recording paper 41.

Here, according to the test recording image, it can be seen that the diameter of the second ink dot 47b is smaller than the diameters of the other ink dots 47a, 47c, 47d, 47e, 47f, and 47g. Further, it can be seen that the landing position of the sixth ink dot 47f is shifted downward (Y2 side direction) compared to the landing positions of the other ink dots 47a, 47b, 47c, 47d, 47e, and 47g. As a result, between the first ink dot 47a and the second ink dot 47b, between the second ink dot 47b and the third ink dot 47c, and between the fifth ink dot 47e and the sixth ink dot 47f, respectively. White streaks 49 extending in the main scanning direction X are generated. Therefore, when printing is actually performed using the above-described ink jet printing apparatus, the third drive pulse P3c is input to the sixth piezoelectric actuator 10f. On the other hand, the second drive pulse P3b is input to the first to fifth and seventh piezoelectric actuators 10a, 10b, 10c, 10d, 10e, and 10g.

(Actual recording by inkjet recording device)
Next, a description will be given of a process when actual printing is performed using the ink jet printing apparatus.

First, the recording paper 41 is transported to a desired position by the transport motor 26 and the transport roller 42, and the inkjet head 1 is transported from X1 to X2 along the carriage shaft 17. At the same time, the reference pulse generation circuit 30 generates the first reference pulse P4a at a predetermined cycle. Then, the sixth switch circuit 31f inputs the third drive pulse P3c. On the other hand, the first to fifth and seventh switch circuits 31a, 31b, 31c, 31d, 31e, 31g each receive the second drive pulse P3b.

At this time, when the preliminary pulse P1 of the third drive pulse P3c is input, as shown in FIG. 9, the ink meniscus 45 at the tip of the sixth nozzle 2f performs the same damped oscillation as described above. Here, at the start of the input of the ejection pulse P2 of the third drive pulse P3c, the cross-sectional shape of the ink meniscus 45 orthogonal to the main scanning direction X is asymmetric with respect to the axis A of the sixth nozzle 2f, and the actual printing is performed. The third drive pulse P3c is formed such that the landing position of the sixth ink dot 47f moves in the Y1 direction from the landing position of the sixth ink dot 47f of the test print image. Therefore, the ejection direction of the ink droplet ejected from the sixth nozzle 2f changes according to the input of the ejection pulse P2 of the third drive pulse P3c. As a result, as shown in FIG. 13, the landing position of the sixth ink dot 47f during the actual printing moves in the Y1 side from the landing position of the sixth ink dot 47f of the test print image.

に よ り As described above, the white streak 49 extending in the main scanning direction X between the fifth ink dot 47e and the sixth ink dot 47f disappears in the test print image. According to the present embodiment, by inputting the preliminary pulse P1 of the third drive pulse P3c by the sixth switch circuit 31f, the cross-sectional shape of the ink meniscus 45 at the tip end of the sixth nozzle 2f orthogonal to the main scanning direction X. Becomes asymmetric with respect to the axis A of the sixth nozzle 2f. Therefore, when the third drive pulse P3c is input, the ink droplet corresponding to the sixth nozzle 2f is ejected in a direction shifted from the axis A of the sixth nozzle 2f. Therefore, the landing position of the sixth ink dot 47f during the actual printing moves to the Y1 side from the landing position of the sixth ink dot 47f of the test print image. Accordingly, it is possible to prevent the white streak 49 extending in the main scanning direction X between the fifth ink dot 47e and the sixth ink dot 47f on the recording paper 41.

(Embodiment 3)
The inkjet recording apparatus according to the present embodiment performs test recording before actually performing recording using the inkjet recording apparatus, and changes the diameter of ink dots. It has almost the same configuration as the ink jet recording apparatus of the first embodiment. Hereinafter, a configuration different from the first embodiment will be described.

よ う As shown in FIG. 14, the second reference pulse P4b has the preliminary pulse P1 and the ejection pulse P2 alternately.

By the way, what drive pulse P3 is input to each piezoelectric actuator 10 by each switch circuit 31 is determined in advance based on the result of test recording described later. In the present embodiment, a fourth drive pulse P3d described later is input to the second piezoelectric actuator 10b. On the other hand, a later-described fifth drive pulse P3e is input to the first, third to seventh piezoelectric actuators 10a, 10c, 10d, 10e, 10f, and 10g. In the present invention, the first nozzle corresponds to the second nozzle 2b, and the second nozzle corresponds to the first, third to seventh nozzles 2a, 2c, 2d, 2e, 2f, 2g.

More specifically, as shown in FIG. 15A, the second switch circuit 31b turns on the transistor for one cycle of the second reference pulse P4b, so that the same fourth driving as the second reference pulse P4b is performed. A pulse P3d is generated. Then, the second switch circuit 31b inputs the fourth drive pulse P3d to the second piezoelectric actuator 10b.

On the other hand, each of the first and third to seventh switch circuits 31a, 31c, 31d, 31e, 31f, and 31g, as shown in FIG. 15B, activates a transistor when the preliminary pulse P1 of the second reference pulse P4b is output. The fifth drive pulse P3e is generated by turning off. The first and third to seventh switch circuits 31a, 31c, 31d, 31e, 31f, 31g correspond to the first and third to seventh piezoelectric actuators 10a, 10c, 10d, 10e, 10f, 10g, respectively. The fifth drive pulse P3e is input.

In this way, each switch circuit 31 selectively supplies a driving pulse composed of the preliminary pulse P1 and the ejection pulse P2 in order and a driving pulse composed of the ejection pulse P2 to each piezoelectric actuator 10. ing.

(Test recording by inkjet recording device)
Next, a description will be given of a test recording process performed before actually performing recording using the ink jet recording apparatus.

First, a test print image for one scan of the inkjet head 1 is recorded on the recording paper 41 in the same manner as described above.

Here, according to the test print image shown in FIG. 12, it can be seen that the diameter of the second ink dot 47b is smaller than the diameters of the other ink dots 47a, 47c, 47d, 47e, 47f, and 47g. Further, it can be seen that the landing position of the sixth ink dot 47f is shifted downward (Y2 side direction) compared to the landing positions of the other ink dots 47a, 47b, 47c, 47d, 47e, and 47g. As a result, between the first ink dot 47a and the second ink dot 47b, between the second ink dot 47b and the third ink dot 47c, and between the fifth ink dot 47e and the sixth ink dot 47f, respectively. White streaks 49 extending in the main scanning direction X are generated. Therefore, when printing is actually performed using the above-described ink jet printing apparatus, a fourth drive pulse P3d is input to the second piezoelectric actuator 10b. On the other hand, a fifth drive pulse P3e is input to the first, third to seventh piezoelectric actuators 10a, 10c, 10d, 10e, 10f, and 10g.

(Actual recording by inkjet recording device)
Next, a description will be given of a process when actual printing is performed using the ink jet printing apparatus.

First, the recording paper 41 is transported to a desired position by the transport motor 26 and the transport roller 42, and the inkjet head 1 is transported from X1 to X2 along the carriage shaft 17. At this time, the reference pulse generating circuit 30 simultaneously generates the second reference pulse P4b at a predetermined cycle. Then, the second switch circuit 31b receives the fourth drive pulse P3d. On the other hand, the first, third to seventh switch circuits 31a, 31c, 31d, 31e, 31f, 31g each receive a fifth drive pulse P3e.

At this time, as shown in FIG. 16, when the preliminary pulse P1 of the fourth drive pulse P3d is input, the ink meniscus 45 at the tip of the second nozzle 2b performs the same damping motion as described above. Here, the fourth drive pulse P3d is formed such that the ink meniscus 45 is located at a position displaced closer to the tip end of the nozzle 2 than the reference position at the start of the input of the ejection pulse P2 of the fourth drive pulse P3d. Therefore, the ejection amount of the ink droplet ejected from the second nozzle 2b by the input of the ejection pulse P2 of the fourth drive pulse P3d is larger than that when the second drive pulse P3b is input. Accordingly, as shown in FIG. 17, the diameter of the second ink dot 47b at the time of actual printing becomes larger than the diameter of the second ink dot 47b of the test print image.

As described above, in the test recording image, the white stripe 49 extending in the main scanning direction X between the first ink dot 47a and the second ink dot 47b and between the second ink dot 47b and the third ink dot 47c. Disappears.

According to the present embodiment, since the ink meniscus 45 at the tip of the second nozzle 2b vibrates when the second switch circuit inputs the preliminary pulse P1 of the fourth drive pulse P3d, the second ink in the actual printing is The diameter of the dot 47b becomes larger than the diameter of the second ink dot 47b of the test print image. Therefore, the generation of the white streak 49 extending in the main scanning direction X between the first ink dot 47a and the second ink dot 47b and between the second ink dot 47b and the third ink dot 47c on the recording paper 41 is prevented. can do. Further, since it is not necessary to perform N-pass printing as in the related art, it is possible to prevent a reduction in printing speed. As described above, it is possible to prevent the occurrence of the white streak 49 extending in the main scanning direction X on the recording paper 41 and to prevent the recording speed from decreasing.

(Embodiment 4)
In the ink jet recording apparatus according to the present embodiment, the shape of the cross section orthogonal to the main scanning direction in the ink flow path portion including the nozzle and the pressure chamber is asymmetric with respect to the axis of symmetry of the pressure chamber, and the other points are The configuration is almost the same as that of the ink jet recording apparatus of the first embodiment. Hereinafter, a configuration different from the first embodiment will be described.

As shown in FIGS. 18 and 19, the first to seventh nozzles 2a, 2b, 2c, 2d, 2e, 2f, 2g and the first to seventh pressure chambers 4a, 4b, 4c, 4d, 4e, 4f, 4g. The cross-sectional shape orthogonal to the main scanning direction X in the first to seventh ink flow path portions 8a, 8b, 8c, 8d, 8e, 8f, and 8g is represented by the symmetric axis B of the pressure chamber 4 (see FIG. 19). Are asymmetric with respect to. Specifically, as shown in FIG. 18, the first to seventh nozzles 2a, 2b, 2c, 2d, 2e, 2f, 2g are respectively located on the lower surface side of the pressure chamber 4 on the lower surface of the inkjet head 1. ing. As shown in FIG. 19, the first to seventh nozzles 2a, 2b, 2c, 2d, 2e, 2f, 2g are respectively located on the lower right side of the pressure chamber 4 on the lower surface of the inkjet head 1.

According to the present embodiment, since the first to seventh nozzles 2a, 2b, 2c, 2d, 2e, 2f, 2g are respectively located on the right end side of the pressure chamber 4 on the lower surface of the inkjet head 1, the second nozzle When the preliminary pulse P1 is input to the second, fourth, and sixth piezoelectric actuators 10b, 10d, and 10f by the fourth and sixth switch circuits 31b, 31d, and 31f, the second, fourth, and sixth nozzles 2b, The shapes of the cross sections of the ink meniscus 45 at the tips 2d and 2f perpendicular to the main scanning direction X are surely asymmetric with respect to the axis A of the nozzle 2. Therefore, the landing positions of the 2N-th second, fourth, and sixth ink dots 47b, 47d, and 47f from the left are changed to the landing positions of the 2N-1st second, fourth, and sixth ink dots 47b, 47d, and 47f from the left. It can be reliably moved to the Y1 side from the position.

In the present embodiment, the first to seventh nozzles 2a, 2b, 2c, 2d, 2e, 2f, 2g are respectively located on the lower right side of the pressure chamber 4 on the lower surface of the ink jet head 1; As shown in (a), the nozzles 2 may be respectively located on the lower end side of the pressure chamber 4 on the lower surface of the inkjet head 1. Further, as shown in FIG. 20B, the cross-sectional shape of the nozzle 2 itself orthogonal to the main scanning direction X may be asymmetric with respect to the axis A of the nozzle 2. Further, as shown in FIG. 20C, each of the nozzles 2 is located on the lower end side of the pressure chamber 4 on the lower surface of the ink jet head 1 and the lower nozzle 2 is located on the left side of the upper nozzle 2. Is also good.

(Embodiment 5)
The ink jet recording apparatus according to the present embodiment performs an ON / OFF switching operation of a switch circuit, that is, performs switching at every printing cycle. In other respects, the ink jet recording apparatus is almost the same as the ink jet recording apparatus of the first embodiment. It has the same configuration. Hereinafter, a configuration different from the first embodiment will be described.

The reference pulse generation circuit 30 is a circuit that generates a third reference pulse P4c (see FIG. 21) as the drive pulse P3.

As shown in FIG. 21, the third reference pulse P4c alternately has a first constituent pulse P41 composed of a discharge pulse P2 and a second constituent pulse P42 composed of a preliminary pulse P1 and a discharge pulse P2 arranged in order. Note that the predetermined printing cycle referred to in the present invention corresponds to the cycle at which the second configuration pulse P42 is input to the piezoelectric actuator 10, and a printing cycle different from the predetermined printing cycle corresponds to the first configuration pulse for the piezoelectric actuator 10. This corresponds to the cycle in which the pulse P41 is input. Further, the first reference pulse according to the present invention corresponds to the second constituent pulse P42, and the second reference pulse corresponds to the first constituent pulse P41.

{Also, the amplitude V1-V3 of the ejection pulse P2 of the first component pulse P41 is different from the amplitude V1-V4 of the ejection pulse P2 of the second component pulse P42. Specifically, the amplitude V1-V4 of the ejection pulse P2 of the second component pulse P42 is smaller than the amplitude V1-V3 of the ejection pulse P2 of the first component pulse P41. Furthermore, the slope of the rising waveform P21 of the ejection pulse P2 of the first component pulse P41 is different from the slope of the rising waveform P21 of the ejection pulse P2 of the second component pulse P42. Specifically, the slope of the rising waveform P21 of the ejection pulse P2 of the second component pulse P42 is larger than the slope of the rising waveform P21 of the ejection pulse P2 of the first component pulse P41.

When the inkjet head 1 is moving in the main scanning direction, the first to seventh switch circuits 31a, 31b, 31c, 31d, 31e, 31f, and 31g are turned on in each printing cycle. , A driving pulse P3 that is the same as the third reference pulse P4c, and the driving pulse P3 is input to the first to seventh piezoelectric actuators 10a, 10b, 10c, 10d, 10e, 10f, and 10g. In other words, in this embodiment, the switching of the switch circuit 31 only needs to be performed once to form one pixel (one ink dot 47).

As a result, as shown in FIG. 22, the first to seventh piezoelectric actuators 10a, 10b, 10c, 10d, 10e, 10f, 10g are formed by the first to seventh switch circuits 31a, 31b, 31c, 31d, 31e, 31f, 31g. The first to seventh ink dots 47a, 47b, 47c, 47d, 47e, 47f, 47g when the second component pulse P42 is input for 10g (2N-th first to seventh ink dots from the left in FIG. 22). The landing positions of the ink dots 47a, 47b, 47c, 47d, 47e, 47f, and 47g are determined by the first to seventh ink dots 47a, 47b, 47c, 47d, 47e, and 47f when the first constituent pulse P41 is input. , 47g (in FIG. 22, the 2N-1st first to seventh ink dots 47a, 47b, 47c, 47d, 47e, 47 , Than landing position 47 g) moves in the direction of Y1 side.

According to the present embodiment, the first to seventh piezoelectric actuators 10a, 10b, 10c, 10d, 10e, 10f, 10g are controlled by the first to seventh switch circuits 31a, 31b, 31c, 31d, 31e, 31f, 31g. The first constituent pulse P41 is input during the predetermined printing cycle, and the second constituent pulse P42 is input during the printing cycle following the predetermined printing cycle. Generation of white streaks extending in the main scanning direction X can be prevented beforehand.

Further, since the third reference pulse P4c has a first component pulse P41 composed of the ejection pulse P2 and a second component pulse P42 in which the preliminary pulse P1 and the ejection pulse P2 are sequentially arranged, the respective switch circuits 31 The drive pulse P3 can be generated by performing the ON / OFF switching operation for each printing cycle. Therefore, drive pulse P3 can be easily generated in switch circuit 31, and as a result, the configuration of switch circuit 31 can be simplified.

By the way, when the second configuration pulse P42 is input to the piezoelectric actuator 10 by the switch circuit 31, the ejection amount of the ink droplet is smaller than that of the ink droplet discharged from the nozzle 2 by inputting the first configuration pulse P41. In some cases, the discharge speed of ink droplets increases.

Here, according to the present embodiment, the ejection amount of the ink droplet ejected from the nozzle 2 by inputting the second constituent pulse P42 and the ink droplet ejected from the nozzle 2 by inputting the first constituent pulse P41 In order to correct the difference with the ejection amount of the first component pulse P2, the amplitude V1-V4 of the ejection pulse P2 of the second component pulse P42 is smaller than the amplitude V1-V3 of the ejection pulse P2 of the first component pulse P41. Therefore, the ejection amount of the ink droplet ejected from the nozzle 2 by inputting the first constituent pulse P41 and the ejection amount of the ink droplet ejected from the nozzle 2 by inputting the second constituent pulse P42 can be made uniform. Can be planned.

Further, correction of the difference between the ejection speed of the ink droplet ejected from the nozzle 2 by inputting the second component pulse P42 and the ejection speed of the ink droplet ejected from the nozzle 2 by inputting the first component pulse P41. In order to achieve this, the slope of the rising waveform P21 of the ejection pulse P2 of the second component pulse P42 is larger than the slope of the rising waveform P21 of the ejection pulse P2 of the first component pulse P41. Therefore, the ejection speed of the ink droplet ejected from the nozzle 2 by inputting the second component pulse P42 and the ejection speed of the ink droplet ejected from the nozzle 2 by inputting the first component pulse P41 are made uniform. Can be planned. As described above, it is possible to prevent the occurrence of image unevenness on the recording paper 41 due to the input of the second configuration pulse P42.

In the present embodiment, the third reference pulse P4c has the first constituent pulse P41 and the second constituent pulse P42 alternately. However, as long as the third reference pulse P4c has the second constituent pulse P42, the third reference pulse P4c is not limited. May be.

In the present embodiment, the slope of the rising waveform P21 of the ejection pulse P2 of the second constituent pulse P42 is larger than the slope of the rising waveform P21 of the ejection pulse P2 of the first constituent pulse P41. The slope of the falling waveform P22 of the pulse P2 may be smaller than the slope of the falling waveform P22 of the ejection pulse P2 of the first constituent pulse P41.

In the present embodiment, the amplitude V1-V4 of the ejection pulse P2 of the second component pulse P42 is smaller than the amplitude V1-V3 of the ejection pulse P2 of the first component pulse P41, and the amplitude V1-V3 of the ejection pulse P2 of the second component pulse P42 is smaller. The slope of the rising waveform P21 is larger than the slope of the rising waveform P21 of the ejection pulse P2 of the first constituent pulse P41. However, when the second component pulse P42 is input, the ejection amount of the ink droplet is reduced as compared with the ink droplet ejected from the nozzle 2 by inputting the first component pulse P41, and the ejection speed of the ink droplet is reduced. Is improved, the amplitude V1-V4 of the ejection pulse P2 of the second constituent pulse P42 is larger than the amplitude V1-V3 of the discharge pulse P2 of the first constituent pulse P41, and the discharge pulse P2 of the second constituent pulse P42 is The slope of the rising waveform P21 may be smaller than the slope of the rising waveform P21 of the ejection pulse P2 of the first constituent pulse P41.

(Embodiment 6)
In the ink jet recording apparatus according to the present embodiment, the amplitude of the preliminary pulse and the amplitude of the ejection pulse are the same, and the pulse width of the preliminary pulse is 1/40 to 1/5 of the Helmholtz period of the head. In this regard, the configuration is substantially the same as that of the ink jet recording apparatus of the fourth embodiment. Hereinafter, a configuration different from the fourth embodiment will be described.

As shown in FIG. 23, the preliminary pulse P1 and the ejection pulse P2 of the drive pulse P3 are formed in a rectangular shape. The amplitude V1-V5 of the preliminary pulse P1 and the amplitude V1-V5 of the ejection pulse P2 are the same. The pulse width of the preliminary pulse P1 is 1/40 to 1/5 of the Helmholtz period of the head. Further, the pulse width of the ejection pulse P2 is preferably の of the Helmholtz period of the head in order to sufficiently utilize resonance.

According to the present embodiment, since the amplitude V1-V5 of the preliminary pulse P1 and the amplitude V1-V5 of the ejection pulse P2 are the same, as shown in FIG. By performing the operation, the driving pulse P3 can be generated. Therefore, the drive pulse P3 can be easily generated.

Further, since the pulse width of the preliminary pulse P1 is 1/40 or more of the Helmholtz period of the head, the preliminary pulse P1 is input to the piezoelectric actuator 10 by the switch circuit 31, so that the ink meniscus 45 Can be vibrated. Further, since the pulse width of the preliminary pulse P1 is 1/5 or less of the Helmholtz period of the head, even if the preliminary pulse P1 is input to the piezoelectric actuator 10 by the switch circuit 31, no ink droplet is ejected from the nozzle 2. As described above, by inputting the drive pulse P3 to the piezoelectric actuator 10 by the switch circuit 31, one or both of the diameter and the impact position of the ink dot 47 can be reliably changed.

In the present embodiment, since the drive pulse P3 can be input to the piezoelectric actuator 10 only by performing ON / OFF switching operation at a constant voltage in the switch circuit 31, it is not necessary to separately provide the reference pulse generation circuit 30.

(Embodiment 7)
The ink jet recording apparatus according to the present embodiment uses a preliminary pulse as a pre-vibration pulse, and otherwise has substantially the same configuration as the ink jet recording apparatus of the first embodiment. Hereinafter, a configuration different from the first embodiment will be described.

As shown in FIG. 24, the second, fourth, and sixth switch circuits 31b, 31d, and 31f are turned off when the second and third ejection pulses P2 from the left and the fourth preliminary pulse P1 from the left are output, respectively. Thus, the sixth drive pulse P3f is generated. Then, the second, fourth and sixth switch circuits 31b, 31d and 31f input the sixth drive pulse P3f to the second, fourth and sixth piezoelectric actuators 10b, 10d and 10f, respectively. The third drive pulse referred to in the present invention corresponds to the second preliminary pulse P1 from the left and the third preliminary pulse P1 from the left.

Here, the second and third preliminary pulses P1 from the left are used as preliminary vibration pulses. The preliminary vibration pulse is a pulse for preventing the ink in the pressure chamber 4 from drying and increasing the viscosity.

According to the present embodiment, the second, fourth, and sixth switch circuits 31b, 31d, 31f input the sixth drive pulse P3f to the second, fourth, and sixth piezoelectric actuators 10b, 10d, 10f, respectively. Therefore, the second and third preliminary pulses P1 from the left can be used as preliminary vibration pulses. Therefore, it is possible to prevent the ink in the pressure chamber 4 from drying and increasing the viscosity.

In the present embodiment, the second and third preliminary pulses P1 from the left are used as preliminary vibration pulses, but any preliminary pulse P1 may be used as preliminary vibration pulses.

(Embodiment 8)
In the ink jet recording apparatus according to the present embodiment, when the switch circuit sequentially supplies the first, second, and third first drive pulses referred to in the present invention, the first first drive pulse and the first In this embodiment, the interval between the second first drive pulse and the second first drive pulse is different from the interval between the second first drive pulse and the third first drive pulse. The configuration is almost the same as that of the ink jet recording apparatus. Hereinafter, a configuration different from the first embodiment will be described.

As shown in FIG. 25, the second, fourth, and sixth switch circuits 31b, 31d, and 31f respectively include the preliminary pulses P1 other than the 6N−4th and 6Nth (N is a natural number) from the left, that is, the first, By turning off the third, fourth, fifth, seventh,... Preliminary pulses P1, the seventh drive pulse P3g is generated. Then, the second, fourth and sixth switch circuits 31b, 31d and 31f input the seventh drive pulse P3g to the second, fourth and sixth piezoelectric actuators 10b, 10d and 10f, respectively. The first first drive pulse referred to in the present invention corresponds to the 6N-4th preliminary pulse P1 and ejection pulse P2 from the left, and the second first drive pulse corresponds to the 6Nth preliminary pulse P1 from the left. And the third first drive pulse corresponds to the 6N + 2nd preliminary pulse P1 and the discharge pulse P2 from the left. In this way, each switch circuit 31 selectively supplies the drive pulse composed of the preliminary pulse P1 and the discharge pulse P2 in order and the drive pulse composed of the discharge pulse P2 to each piezoelectric actuator 10. ing.

Thereby, as shown in FIG. 26, the landing positions of the 6N-4th and 6Nth second, fourth, and sixth ink dots 47b, 47d, and 47f from the left are the other second, fourth, and fourth ink dots, respectively. The ink dots 47b, 47d, and 47f move in the Y1 side from the landing positions. In other words, changing the landing position of the ink dot 47 in the Y direction is not performed periodically.

When the ejection pulse P2 is inputted after the preliminary pulse P1 is inputted to the piezoelectric actuator 10, the ejection speed of the ink droplet ejected from the nozzle 2 may increase. Therefore, the landing positions of the 6N-4th and 6N-th second, fourth, and sixth ink dots 47b, 47d, and 47f from the left move to the left (X1 side direction). Thereby, between the 6N-4th second, fourth, and sixth ink dots 47b, 47d, and 47f from the left and the 6N-3rd second, fourth, and sixth ink dots 47b, 47d, and 47f, and Image unevenness 51 occurs between the 6N-th second, fourth, and sixth ink dots 47b, 47d, and 47f and the 6N + 1-th second, fourth, and sixth ink dots 47b, 47d, and 47f.

By the way, if the first to seventh switch circuits 31a, 31b, 31c, 31d, 31e, 31f, 31g are respectively turned off when the 2N-1st preliminary pulse P1 from the left is output, as shown in FIG. The landing positions of the 2N-th first to seventh ink dots 47a, 47b, 47c, 47d, 47e, 47f, and 47g from the left are respectively the 2N-1st first to seventh ink dots 47a and 47b from the left. , 47c, 47d, 47e, 47f, and 47g move toward the Y1 side from the landing positions.

When the ejection pulse P2 is inputted after the preliminary pulse P1 is inputted to the piezoelectric actuator 10, the ejection speed of the ink droplet ejected from the nozzle 2 may increase. Thus, the 2N-th first to seventh ink dots 47a, 47b, 47c, 47d, 47e, 47f, and 47g from the left and the 2N + 1-th first to seventh ink dots 47a, 47b, 47c, 47d, and 47e from the left. , 47f, and 47g, image unevenness 53 extending in the sub-scanning direction Y occurs. Further, the image unevenness 53 extending in the sub-scanning direction Y occurs at the same interval.

Here, according to the present embodiment, when the input of the 6N-4th ejection pulse P2 from the left to the second, fourth, and sixth piezoelectric actuators 10b, 10d, and 10f starts, and the 6Nth ejection pulse P2 from the left. Since the interval between the start of input and the start of input of the 6Nth ejection pulse P2 from the left and the start of input of the 6N + 2nd ejection pulse P2 from the left are different, the main scanning direction X on the recording paper 41 is different. , Image unevenness 51 occurs at different intervals. Therefore, it is possible to prevent the image unevenness 51 from occurring at the same interval in the main scanning direction X on the recording paper 41.

In addition, since only the ejection pulse P2 is input as the drive pulse P3 to the first, third, fifth, and seventh piezoelectric actuators 10a, 10c, 10e, and 10g, the first, third, fifth, and fifth piezoelectric actuators are input. The ejection speed of ink droplets ejected from the seventh nozzles 2a, 2c, 2e, 2g does not change. Therefore, the landing positions of the first, third, fifth, and seventh ink dots 47a, 47c, 47e, and 47g in the main scanning direction X do not move. Accordingly, the 6N-4th first to seventh ink dots 47a, 47b, 47c, 47d, 47e, 47f, 47g and the 6N-3rd first to seventh ink dots 47a, 47b, 47c, 47d, from the left. 47e, 47f, 47g and the 6N-th first to seventh ink dots 47a, 47b, 47c, 47d, 47e, 47f, 47g and the 6N + 1-th first to seventh ink dots 47a, 47b, 47c, 47d. , 47e, 47f, and 47g can be prevented from generating image unevenness extending in the sub-scanning direction Y.

In the present embodiment, the OFF state is set at the time of outputting the 6N−4th and 6Nth preliminary pulses P1 from the left. However, image irregularities extending in the sub-scanning direction Y on the recording paper 41 are spaced at different intervals. As long as it occurs, the OFF state may be set when any of the preliminary pulses P1 is output.

In the present embodiment, only the ejection pulse P2 is input as the drive pulse P3 to the first, third, fifth, and seventh piezoelectric actuators 10a, 10c, 10e, and 10g, but the invention is not limited to this. However, it is sufficient that only the ejection pulse P2 is input as the drive pulse P3 to at least one of the first to seventh piezoelectric actuators 10a, 10b, 10c, 10d, 10e, 10f, and 10g.

(Other embodiments)
In addition, in each of the above embodiments, the diaphragm 11 also serves as the common electrode, but the diaphragm and the common electrode may be separately provided.

In each of the above embodiments, the piezoelectric element 13 is made of PZT, but may be made of PbTiO ₃ or the like. Further, a piezoelectric element having a different thickness from the above embodiments may be used.

In addition, in each of the above embodiments, the diaphragm 11 is formed on the partition wall 7, but the individual electrodes 14 may be formed on the partition wall 7. At this time, the vibration plate 11 is formed on the piezoelectric element 13.

  Further, the diaphragm 11, the individual electrodes 14, the nozzle plate 6, the partition wall 7, and the like may be made of a material and a thickness different from those of the above embodiments.

Also, in each of the above embodiments, the rising waveforms P11 and P21 are output after the falling waveforms P12 and P22. However, the falling waveforms P12 and P22 may be output after the rising waveforms P11 and P21. Note that such a waveform is called a push-pull waveform.

Further, in each of the above embodiments, the recording medium is constituted by the recording paper 41, but may be another recording medium.

In each of the above embodiments, the seven nozzles 2, the pressure chambers 4, and the piezoelectric actuators 10 are formed at predetermined intervals in the sub-scanning direction Y, but any number may be used as long as the number is two or more. .

Further, in the above embodiments, various patterns of the ink dots 47 are shown, but the ink dots whose diameters or landing positions are changed by inputting the preliminary pulse P1 and the ejection pulse P2 to the piezoelectric actuator 10 are shown. It is sufficient that at least one 47 is provided on the recording paper 41.

In addition, it is preferable that the ink dots 47 whose diameters or landing positions are changed by inputting the preliminary pulse P1 and the ejection pulse P2 to the piezoelectric actuator 10 are evenly arranged on the recording paper 41. Here, “the ink dots 47 whose diameters or landing positions have been changed are not evenly arranged on the recording paper 41” means, for example, that the ink dots 47 whose landing positions have been changed are arranged on the left half of the recording paper 41. This means that the ink dots 47 whose landing positions are not changed are arranged in the right half of the recording paper 41, or that the landing positions of all the ink dots 47 are changed and they are arranged on the recording paper 41.

In each of the above embodiments, each switch circuit 31 is configured to selectively supply a drive pulse composed of the preliminary pulse P1 and the ejection pulse P2 arranged in order and a drive pulse composed of the ejection pulse P2. However, a plurality of types of driving pulses including those driving pulses may be selectively supplied.

In the above embodiments, the pressure applying means for applying pressure to the ink in each of the pressure chambers 4 is constituted by the piezoelectric actuator 10, that is, the piezo type, but is constituted by the bubble jet type. Is also good.

As described above, the present invention is useful when applied to printers such as computers, facsimile machines, and copiers.

FIG. 1 is a schematic perspective view illustrating an ink jet recording apparatus according to an embodiment of the present invention. FIG. 3 is a partial bottom view of the inkjet head. FIG. 3 is a sectional view taken along line III-III of FIG. 2. It is a partial sectional view near a piezoelectric actuator. FIG. 5 is a sectional view taken along line VV of FIG. 2. FIG. 3 is a block diagram illustrating a configuration of a driving device. FIG. 4 is a waveform diagram illustrating a first reference pulse. (A) is a waveform diagram showing a first drive pulse, and (b) is a waveform diagram showing a second drive pulse. FIG. 4 is an enlarged sectional view near a nozzle showing a change in ink meniscus. FIG. 5 is a diagram illustrating an ink dot pattern during recording. FIG. 9 is a waveform diagram illustrating a third drive pulse. FIG. 3 is a diagram illustrating an ink dot pattern during test recording. FIG. 3 is a diagram illustrating an ink dot pattern during actual printing. FIG. 9 is a waveform diagram showing a second reference pulse. (A) is a waveform diagram showing a fourth drive pulse, and (b) is a waveform diagram showing a fifth drive pulse. FIG. 4 is an enlarged sectional view near a nozzle showing a change in ink meniscus. FIG. 3 is a diagram illustrating an ink dot pattern during actual printing. FIG. 3 is a partial bottom view of the inkjet head. FIG. 19 is a sectional view taken along line VII-VII of FIG. 18. (A) is an enlarged sectional view near the nozzle and the pressure chamber, (b) is an enlarged sectional view near the nozzle, and (c) is an enlarged sectional view near the nozzle and the pressure chamber. FIG. 9 is a waveform chart showing a third reference pulse. FIG. 3 is a diagram illustrating an ink dot pattern during actual printing. FIG. 4 is a waveform diagram illustrating a driving pulse. FIG. 14 is a waveform diagram illustrating a sixth drive pulse. FIG. 14 is a waveform chart showing a seventh drive pulse. FIG. 3 is a diagram illustrating an ink dot pattern during actual printing. FIG. 4 is a diagram illustrating a pattern of ink dots. FIG. 9 is a diagram showing a conventional ink dot pattern. FIG. 9 is a diagram showing a conventional ink dot pattern.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Ink jet head 2 Nozzle 4 Pressure chamber 10 Piezoelectric actuator 16 Carriage 17 Carriage shaft 28 Carriage motor 30 Reference pulse generation circuit (reference pulse generation means)
31 switch circuit (drive pulse supply means)
41 Recording paper (recording medium)
P1 Preparatory pulse P2 Discharge pulse P3 Drive pulse P4 Reference pulse

Claims (16)

A head body in which a plurality of nozzles and a plurality of pressure chambers communicating with the respective nozzles and containing the ink are formed; and a recording medium for applying a pressure to the ink in the respective pressure chambers to cause ink droplets from the respective nozzles A plurality of pressure applying means to be discharged to, and a driving pulse supply means for supplying a drive pulse for driving each of the pressure applying means to each of the pressure applying means,
The nozzle includes at least a first nozzle and a second nozzle arranged in a relative movement orthogonal direction orthogonal to a direction in which the ink is ejected relative to the recording medium,
The driving pulse supply means includes: a first driving pulse in which a preliminary pulse for oscillating a meniscus of the ink at the tip of the nozzle and a discharge pulse for discharging an ink droplet from the nozzle are sequentially arranged; And a second driving pulse composed of a pulse. The first driving pulse is supplied to the pressure applying means corresponding to the first nozzle, and the pressure applying means corresponding to the second nozzle is supplied. An ink jet recording apparatus for supplying the second drive pulse to the ink jet recording apparatus. A head body in which a plurality of nozzles and a plurality of pressure chambers communicating with the respective nozzles and containing the ink are formed; and a recording medium for applying a pressure to the ink in the respective pressure chambers to cause ink droplets from the respective nozzles A plurality of pressure applying means to be discharged to, and a driving pulse supply means for supplying a drive pulse for driving each of the pressure applying means to each of the pressure applying means,
The nozzle includes a plurality of nozzles arranged in a relative movement orthogonal direction orthogonal to the direction of relative movement with respect to the recording medium at the time of ink ejection,
The driving pulse supply means includes: a first driving pulse in which a preliminary pulse for oscillating a meniscus of the ink at the tip of the nozzle and a discharge pulse for discharging an ink droplet from the nozzle are sequentially arranged; And a second drive pulse composed of pulses. The first drive pulse is supplied to a pressure applying unit corresponding to at least one of the plurality of nozzles during a predetermined printing cycle. And an ink jet recording apparatus that supplies the second drive pulse during a printing cycle different from the predetermined printing cycle. Reference pulse generating means for generating a reference pulse including a first reference pulse in which the preliminary pulse and the ejection pulse are sequentially arranged and a second reference pulse including the ejection pulse,
3. An ink jet recording apparatus according to claim 2, wherein said drive pulse supply means supplies said pressure pulse generating means with said reference pulse generated by said reference pulse generation means as said drive pulse. 4. The ink jet recording apparatus according to claim 3, wherein the waveform of the ejection pulse of the first reference pulse is different from the waveform of the ejection pulse of the second reference pulse. The drive pulse supply unit is configured to supply at least three first, second, and third first drive pulses in order between the first first drive pulse and the second first drive pulse. The ink jet recording apparatus according to any one of claims 1 to 4, wherein an interval between the first and second driving pulses is different from an interval between the second and third driving pulses. A head body in which a plurality of nozzles and a plurality of pressure chambers communicating with the respective nozzles and containing the ink are formed; and a recording medium for applying a pressure to the ink in the respective pressure chambers to cause ink droplets from the respective nozzles A plurality of pressure applying means to be discharged to, and a driving pulse supply means for supplying a drive pulse for driving each of the pressure applying means to each of the pressure applying means,
The nozzle includes at least a first nozzle and a second nozzle arranged in a relative movement orthogonal direction orthogonal to a direction in which the ink is ejected relative to the recording medium,
When the same drive pulse is supplied to both the pressure applying means corresponding to the first and second nozzles, the ink droplet ejected from the second nozzle has a predetermined reference diameter and a reference landing position on the recording medium. While forming an ink dot, the ink droplet ejected from the first nozzle forms an ink dot having a diameter different from a predetermined reference diameter and / or a landing position shifted from the reference landing position on the recording medium. An ink jet recording apparatus,
The driving pulse supply means includes: a first driving pulse in which a preliminary pulse for oscillating a meniscus of the ink at the tip of the nozzle and a discharge pulse for discharging an ink droplet from the nozzle are sequentially arranged; And a second driving pulse composed of a pulse. The first driving pulse is supplied to the pressure applying means corresponding to the first nozzle, and the pressure applying means corresponding to the second nozzle is supplied. An ink jet recording apparatus for supplying the second drive pulse to the ink jet recording apparatus. A reference pulse generating means for generating a reference pulse for driving each of the pressure applying means,
The reference pulse includes the preliminary pulse and the ejection pulse,
The drive pulse supply means generates one of the first and second drive pulses from the preliminary pulse and the ejection pulse generated by the reference pulse generation means, and supplies the one to the pressure applying means. 7. The ink jet recording apparatus according to any one of 1, 2, and 6. The amplitude of the preliminary pulse and the amplitude of the ejection pulse are the same, and the pulse width of the preliminary pulse is 1/40 to 1/5 of the Helmholtz period of the head. Ink jet recording device. The inkjet according to any one of claims 1 to 8, wherein an interval between the start of the supply of the preliminary pulse and the start of the supply of the ejection pulse in the first drive pulse is equal to or less than twice the Helmholtz period of the head. Expression recording device. Landing of the first ink dot formed by supplying the second drive pulse to the pressure applying means and the second ink dot formed by supplying the first drive pulse to the pressure applying means in the direction perpendicular to the relative movement. The ink jet recording apparatus according to claim 1, wherein the positions are different. The cross-sectional shape orthogonal to the relative movement direction of the ink meniscus at the tip of the nozzle corresponding to the pressure applying means when the preliminary pulse is supplied to the pressure applying means is asymmetric with respect to the axis of the nozzle. 11. The ink jet recording apparatus according to item 10. 13. The ink jet recording apparatus according to claim 11, wherein each of the nozzles arranged in the direction perpendicular to the relative movement is provided at a position shifted from the center of the pressure chamber communicating with the nozzle in the direction perpendicular to the relative movement. The ink jet recording apparatus according to any one of claims 10 to 12, wherein the shapes of the cross sections of the nozzles arranged in the direction perpendicular to the relative movement are orthogonal to the axis of the nozzle. The distance between the center position of the first ink dot and the center position of the second ink dot in the direction perpendicular to the relative movement is not more than の of the pitch of the ink dots. 3. The ink jet recording apparatus according to claim 1. 15. The driving pulse supply unit according to claim 1, wherein a third driving pulse including the preliminary pulse is selectively supplied as the driving pulse in addition to the first driving pulse and the second driving pulse. 5. An ink jet recording apparatus according to any one of the preceding claims. The ink jet recording apparatus according to any one of claims 1 to 15, wherein the pressure applying means comprises a piezoelectric element.

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