JP3484940B2 - Ink jet recording apparatus and drive signal adjusting method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to an ink jet type recording apparatus comprising an ink jet recording head for ejecting the size ink droplets of different from the same nozzle, and, their
Drive signal adjustment method, in particular, ejects minute ink droplets.
Regarding the drive signal to be output .

[0002]

BACKGROUND ART inkjet Tsu preparative type recording apparatus, based on the dot pattern data recording data formed by expanded sent from the host computer, ink droplets are ejected at each predetermined timing from the nozzles of the recording head, Each of these ink droplets forms a dot on the surface of a recording medium such as recording paper to perform recording.
As described above, the ink jet recording apparatus controls whether or not ink droplets are ejected, that is, controls on / off of dots. Therefore, the intermediate gradation cannot be recorded and output as it is.

Therefore, a technique has been proposed in which ink droplets of different weights are ejected from the same nozzle to enable gradation expression. As such an inkjet recording device,
The pressure generating chamber containing the ink is expanded to largely retract the ink meniscus, and then the pressure generating chamber is contracted to eject an ink drop to generate a normal dot. By contracting and expanding the ink so that it does not eject, the meniscus of the ink is retracted to a greater extent than in the case of normal dots, and then the pressure generating chamber is contracted to eject microscopic ink droplets smaller than normal dots to form microdots. It is known to produce.

In the actuator unit in which the pressure generating chamber is formed, there is a variation in manufacturing for each recording head. Therefore, conventionally, the voltage applied to the piezoelectric vibrator of the actuator unit in order to expand and contract the pressure generating chamber has been changed. The size is changed and adjustment is performed for each head so that the weight of the ejected ink droplet is constant.

[0005]

However, in the driving method for generating microdots, it is only necessary to adjust the magnitude of the applied voltage so that the weight of the ink droplet becomes constant, and the Helmholtz which is the period of vibration of the meniscus. In the case of a recording head having a large cycle Tc, the compliance of the pressure generating chamber is large, and the pressure change is gentle, so that the ink droplet velocity is not increased and the ink droplet is easily ejected. In a recording head with a small Tc, the ink droplet velocity is too high and the ejection state becomes unstable.

In order to keep the ink drop weight and the ink drop velocity of the microdots constant, it is necessary to increase the accuracy of Tc of the recording head, which raises the problem of high manufacturing cost or low product yield. It was

An object of the present invention is to provide an ink jet type recording apparatus capable of keeping the ink droplet speed and ink droplet weight of microdots constant even if the Helmholtz cycle Tc of the recording head varies, and a method of adjusting the drive signal thereof. Especially.

[0008]

According to the ink jet recording apparatus of the first aspect of the present invention or the drive signal adjusting method of the fourth aspect , the pressure generating chamber is operated by operating the pressure generating means. and an ink jet recording head for discharging ink droplets from the nozzle opening by contracting, in
The meniscus of ku will be pulled deep inside the nozzle opening.
Expansion signal for expanding the urchin pressure generating chamber, and, bulging Zhang Xin
Occurs when the meniscus is pulled in by the issue
And a drive unit that outputs a drive signal including a first contraction signal that contracts the pressure generation chamber to eject an ink droplet from the nozzle opening to the pressure generation unit, and a duration of the expansion signal is changed. and means for adjusting the speed of the ink droplets ejected by the contraction signal by said a vibration period of the by that meniscus expansion signal relates inherent Helmholtz period Tc for each record head, the period T
To reduce the duration of the higher c is large the expanded signal, increasing the ink droplet speed of the period Tc is large recording head, it is possible to reduce the ink drop velocity period Tc is smaller recording head. In this case, in claim 2
So that the meniscus rises from the nozzle opening
A second contraction signal that pressurizes the pressure generating chamber to
It preferably occurs before the expansion signal.

According to the driving signal adjustment method of according to the ink jet recording apparatus or claim 5 according to claim 3 of the present invention, between the 3/4 of the period Tc and the period Tc duration of the inflation signal Since it is set by, it is possible to greatly adjust the ink drop velocity with a small change in the duration of the signal.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a block diagram for explaining the relationship between a printer main body (hereinafter referred to as the main body) 1 for performing information processing and supplying head driving power, and a recording head 2 to be controlled. The main body 1 supplies control logic 101 for generating and timing data for determining nozzles that eject ink, and sufficient power for generating and driving a voltage waveform for driving the actuator of the head. And a connector 103.

The recording head 2 has a plurality of actuators 211 to 213 formed of piezoelectric elements that generate kinetic energy for ejecting ink, and whether or not the drive voltage from the main body 1 is applied to the actuators. According to the data from the analog switches 221 to 223 and the control logic in the main body 1, the actuators 211 to 221
Analog switch 2 is used to determine whether to vibrate 213.
Control logic 2 controlled by ON / OFF of 21 to 223
01 and. The recording head 2 moves on the carriage shaft in the printer mechanism in the head scanning direction, and data corresponding to the position in the head scanning direction is sent from the main body 1 to eject ink droplets and perform printing. The main body 1 and the recording head 2 are connected by a flexible flat cable (hereinafter referred to as FFC) 3.

FIG. 3 is a sectional view showing the mechanical structure of the recording head 2. The first lid member 30 is composed of a thin plate of zirconia having a thickness of about 6 μm, a common electrode 31 serving as one pole is formed on the surface thereof, and the pressure generating chamber 3 is formed on the surface thereof.
A piezoelectric vibrator 33 made of PZT or the like is fixed so as to face the surface 2, and a drive electrode 34 made of a relatively flexible metal layer such as Au is formed on the surface of the piezoelectric vibrator 33.

Here, the piezoelectric vibrator 33 is the first lid member 3
0 and a flexural vibration type actuator are formed. When the piezoelectric vibrator 33 is charged, it deforms so as to contract to reduce the volume of the pressure generating chamber 32, and when the piezoelectric vibrator 33 is discharged, it expands to generate pressure. It is designed to be deformed in the direction of expanding the volume of the generation chamber.

The spacer 35 is formed by providing a through hole in a ceramic plate of zirconia or the like having a thickness suitable for forming the pressure generating chamber 32, for example, a second cover member 36 and a first cover member. Both sides are sealed with 30 to form a pressure generating chamber 32.

The second lid member 36 is a ceramic plate made of zirconia or the like and has a communication hole 38 for connecting the ink supply port 37 and the pressure generating chamber 32, and a nozzle for connecting the nozzle opening 25 and the end of the pressure generating chamber. A communication hole 39 is provided and is fixed to one surface of the spacer 35.

The first lid member 30, the spacer 35, and the second lid member 36 are formed by molding a clay-like ceramic material into a predetermined shape, and stacking and firing it to use an adhesive. Without actuator unit 21
Are configured.

The ink supply port forming substrate 40 also serves as a fixed substrate of the actuator unit 21, and is provided with an ink supply port 37 for connecting the reservoir 41 and the pressure generating chamber 32 to one end of the pressure generating chamber 32 side. A nozzle communication hole 42 connected to the nozzle opening 25 is provided on the end side.

The reservoir forming substrate 43 receives the inflow of ink from an ink cartridge (not shown).
And a nozzle communication hole 44 connected to the nozzle opening 25 is provided, and one surface is sealed by a nozzle plate 45 to form a reservoir 41.

The ink supply port forming substrate 40, the reservoir forming substrate 43, and the nozzle plate 45 are fixed to each other by adhesive layers 46 and 47 such as a heat-welding film or an adhesive, and constitute the flow path unit 22. There is.

The flow path unit 22 and the actuator unit 21 are fixed to each other by an adhesive layer 48 such as a heat-welding film or an adhesive to form the recording head 10.

With the configuration of the recording head 10 described above, when the piezoelectric vibrator 33 is discharged, the pressure generating chamber 32 expands, the pressure in the pressure generating chamber 32 decreases, and ink flows from the reservoir 41 into the pressure generating chamber. . When the piezoelectric vibrator 33 is charged, the pressure generating chamber 32 contracts, the pressure in the pressure generating chamber 32 rises, and the ink in the pressure generating chamber 32 is ejected from the nozzle openings 25 to the outside.

The procedure for printing with the above configuration will be described with reference to FIGS. 4 and 5. The recording head 2 moves in the head scanning direction with the paper fixed. At that time, the pulse trains shown in A and B of FIG.
It is sent from the main body 1 to the recording head 2 through C3. A is a drive pulse for ejecting minute ink droplets to generate microdots, and B is a drive pulse for generating normal dots larger than microdots. Data that regulates the opening and closing of the analog switches 221 to 223 in synchronization with either the drive pulse A or B is also sent from the main body 1 to the recording head 2, and for a specific pulse,
Only the actuator connected to the closed one of the analog switches 221 to 223 is displaced. As a result of the ink pressure in the pressure generating chamber corresponding to the driven actuator being increased, ink is ejected only from the nozzle corresponding to this among the nozzles 251 to 253 in FIG.

The drive pulse of the microdot shown in A of FIG. 5 has a voltage value starting from the intermediate potential VmM (1
11) Then, the potential rises to a maximum potential VPM with a constant gradient during a predetermined time Twc0 (112), and the maximum potential VPM is maintained for a predetermined time Twh0 (113). Next, the microdot drive pulse drops to the first lowest potential VLS with a constant gradient during a predetermined time Twd1 (114), and maintains the lowest potential VLS for a predetermined time Twh1 (11).
5). Then, the voltage value of the microdot drive pulse rises again to a maximum potential VPM with a constant gradient during a predetermined time Twc1 (116), and the maximum potential VPM is maintained for a predetermined time Tw.
Only h2 is maintained (117). After that, the microdot drive pulse falls to the intermediate potential VmM for a predetermined time Twd2 with a constant gradient (118).

Here, the charging pulse 112 is the piezoelectric vibrator 3
3, the piezoelectric vibrator 33 of FIG. 3 bends in the direction of contracting the volume of the pressure generating chamber 32, and the pressure generating chamber 32
Generate positive pressure inside. As a result, the meniscus rises from the nozzle opening. When the potential difference of the charging pulse 112 is large and the voltage gradient is large, it is possible to eject the ink droplets by the charging pulse 112. The potential difference of 112 is set.
Further, in the present embodiment, the charging time Twc0 of the charging pulse 112 is set to Tc or more so as not to cause vibration of the meniscus Helmholtz cycle Tc.

The meniscus rising by the charging pulse 112 is vibrated in a cycle Tm by the surface tension of the ink while the hold pulse 113 is being applied, and the nozzle opening 25.
Move back inward.

When the discharge pulse 114 is applied, the piezoelectric vibrator 33 bends in the direction of expanding the volume of the pressure generating chamber 32, and a negative pressure is generated in the pressure generating chamber 32. As a result, the movement of the meniscus toward the inside of the nozzle opening 25 is superimposed, and the meniscus is largely drawn into the inside of the nozzle opening 25. In this way, by applying the discharge pulse at the timing when the meniscus moves toward the inside of the nozzle opening 25,
Even with a relatively small potential difference of the discharge pulse 114, the meniscus can be largely drawn into the nozzle opening 25.

When the charging pulse 116 is applied, a positive pressure is generated in the pressure generating chamber 32 and the meniscus rises from the nozzle opening 25. At this time, the meniscus causes the nozzle opening 25
Since a pressure change in the positive pressure direction occurs in a state where the ink is largely drawn inside, the ejected ink droplets become minute ink droplets and generate microdots.

The discharge pulse 118 is a discharge pulse for suppressing the Tc oscillation of the meniscus excited by the discharge pulse 114 and the charging pulse 116, and the meniscus of the nozzle opening 25 is moved at the timing when the Tc oscillation is directed to the outlet of the nozzle opening 25. A discharge pulse 118 is applied to drive it inward.

The drive pulse of the normal dot shown in FIG. 5B starts from the intermediate potential VmN (120) and then the second pulse.
(121) with a constant gradient to the lowest potential VLL of
The lowest potential VLL is maintained for a predetermined time (122). The voltage value of the normal dot drive pulse is the maximum potential V
It rises to PN with a constant gradient (123), and the maximum potential VP
N is maintained for a predetermined time (124). After that, the normal dot drive pulse falls to the intermediate potential VmN with a constant gradient.

When the discharge pulse 121 is applied, a negative pressure is generated in the pressure generating chamber and the meniscus is drawn into the nozzle opening 25. Here, by setting the potential difference of the discharge pulse 121 to be smaller than the potential difference of the discharge pulse 114 of the microdot drive pulse, the meniscus is not largely drawn into the inside of the nozzle opening 25 as compared with the microdot drive pulse.

When the charging pulse 123 is applied, a positive pressure is generated in the pressure generating chamber 32 and the meniscus rises from the nozzle opening 25. At this time, the meniscus causes the nozzle opening 25
Since the pressure change in the positive pressure direction occurs in a state where the ink droplet is not drawn in so much, the ejected ink droplet becomes a larger ink droplet than the microdot.

The discharge pulse 125 is a discharge pulse for suppressing the Tc vibration of the meniscus excited by the discharge pulse 121 and the charge pulse 123, and the meniscus of the meniscus is directed to the outlet of the nozzle opening 25 at the timing when the Tc vibration is directed to the outlet of the nozzle opening 25. A discharge pulse 125 is applied to the interior.

When the recording head 2 finishes moving from one end to the other end in the head scanning direction, the nozzles 251 to 251 are moved in the paper feeding direction.
Paper is fed by a distance of 53. In this way, ink ejection / non-ejection at an arbitrary point on the paper defined by the resolution of the printer is determined by the amount of movement from the leading edge of the paper, which is the recording medium, the position in the scanning direction of the head, that is, the ejection pulse. It can be determined by designating the timing and the nozzles 251 to 253.

By the way, in the above-mentioned recording head 2,
The fluid compliance due to the ink compressibility of the pressure generating chamber 32 is Ci, the rigidity compliance due to the material of the first lid member 30, the piezoelectric vibrator 33, etc. forming the pressure generating chamber 32 is Cv, and the nozzle opening 25. Is Mn and the inertance of the ink supply port 37 is Ms, the Helmholtz resonance frequency F of the pressure generating chamber 32 is expressed by the following equation.

F = 1 / (2π) × √ {(Mn + Ms) /
(Mn × Ms) / (Ci + Cv)} If the compliance of the meniscus is Cn, if the viscous resistance of the ink flow path can be ignored, the natural vibration period T of the meniscus T
m is shown by the following equation.

Tm = 2π × √ {(Mn + Ms) Cn} Further, the volume of the pressure generating chamber 32 is V, the density of the ink is ρ,
When the speed of sound in the ink is c, the fluid compliance Ci is expressed by the following equation.

Ci = V / ρc ² Furthermore, the rigidity compliance Cv of the pressure generating chamber 32
Corresponds to the static deformation rate of the pressure generating chamber 32 when a unit pressure is applied to the pressure generating chamber 32.

The period Tc of the vibration excited in the meniscus by the contraction and extension of the piezoelectric vibrator 33 is the same as the period obtained by the reciprocal of the Helmholtz resonance frequency F. As a specific example, the fluid compliance Ci is 1 × 10 ^−20.
m ⁵ N ⁻¹ , rigidity compliance Cv is 1.5 × 10
^-20 m ⁵ N ⁻¹ , inertance Mn of 2 × 10 ⁸ kg
Helmholtz resonance frequency F when m ⁻⁴ and inertance Ms is 1 × 10 ⁸ kgm ⁻⁴ is 125 kHz,
The Helmholtz period Tc is 8 μs.

The Helmholtz period Tc can be measured directly at the laboratory level, but it is difficult to measure directly at the mass production level because it takes time. Therefore, the resonance frequency of the element is measured by the impedance analyzer in a state where the pressure generating chamber 32 does not contain ink. Since there is a proportional relationship between the resonance frequency in the absence of ink and the Helmholtz period Tc as shown in FIG. 6, Tc can be calculated from the measured value of the resonance frequency.

In the manufacturing process of the recording head, the first lid member 30 forming the pressure generating chamber 32 and the piezoelectric vibrator 3 are formed.
Values such as the rigidity compliance Cv due to materials such as 3 have variations. Therefore, the Helmholtz cycle Tc
Also varies from head to head.

In order to make the weight of the ink droplets ejected from the nozzles of the recording head constant in each head, generally, the magnitude of the voltage applied to the head piezoelectric vibrator is changed so that the weight of the ink droplets ejected is changed. Adjustments are made for each head so that it becomes constant. Specifically, ink droplets are ejected at two different voltages, the weights of the ejected ink droplets are measured, and it is appropriate that the change amount of the ink droplet weight is proportional to the change amount of the voltage. Adjust the voltage so that

However, when ejecting the microdots, the compliance of the pressure generating chamber can be improved in the case of a recording head having a large Helmholtz period Tc simply by adjusting the magnitude of the applied voltage so that the weight of the ink droplet becomes constant. Is large and the pressure change is gentle, the ink drop velocity does not increase and the flight of the ink drop is easy to bend. In a recording head with a small Tc, the ink droplet velocity is too high and the ejection state becomes unstable.

In this embodiment, the ejection speed of the ink droplets is adjusted by changing the duration Twd1 of the discharge pulse 114 of the microdot drive pulse according to the Helmholtz cycle Tc. The principle will be described below.

In FIG. 7, the Helmholtz period Tc is 8.0 μ.
s recording head, Twd1 = 4.0 μs, Tw
FIG. 7 is a diagram showing a state of vibration of a meniscus of ink when a discharge pulse is sent to a piezoelectric vibrator under three conditions of d1 = 6.0 μs and Twd1 = 8.0 μs and the voltage is held as it is.

When microdots are ejected using these recording heads, if Twh1 is 2.0 μs,
When Twd1 = 4.0 μs, the charging pulse 116 for contracting the pressure generating chamber is started at the point indicated by X in FIG. Here, the amount of pull-in is the maximum, but the velocity of the nozzle in the ejection direction is 0, so the velocity of the ink droplet is not the maximum.

When Twd1 = 6.0 μs, that is, T
When wd1 is 3/4 of Tc, the charging pulse 116 for contracting the pressure generating chamber is started at the point indicated by Y in FIG. Here, the velocity of the vibration in the ejection direction of the nozzle is the maximum, and the ink drop velocity with respect to the ink drop weight is the maximum due to the superposition effect due to the start of the charging pulse 116 at this point.

When Twd1 = 8.0 μs, that is, T
When wd1 is equal to Tc, the charging pulse 116 for contracting the pressure generating chamber is started at the point indicated by Z in FIG. Here, the pulling-in amount of the meniscus becomes small, and the ink drop velocity becomes slow. When Twd1 is larger than Tc, the meniscus pull-in amount is further reduced, so that it is impossible to hit the microdots by largely retracting the meniscus to eject a small ink droplet at a high speed.

For the above reason, the ratio of the ink drop velocity to the ink drop weight when Twd1 is changed becomes maximum when Twd1 is 3/4 of Tc as shown in FIG. When Twd1 is between 3/4 and Tc of Tc, the ink drop velocity becomes smaller as Twd1 becomes larger with a substantially constant gradient. When Twd1 becomes larger than Tc, the ink droplet velocity becomes almost constant regardless of Twd1. Therefore, T
When the length of wd1 is changed to adjust the ink drop velocity, if Twd1 is changed between 3/4 and Tc of Tc, the ink drop velocity can be increased with a small change of Twd1. Also, by setting the maximum value of Twd1 to Tc and the minimum value to 3/4 of Tc, it is possible to increase the adjustment range of the ink droplet speed.

Here, as an example, as shown in Table 1,
When the range of variation of the measured value f obtained by sampling and measuring the resonance frequency of the actuator element of the recording head is f0 ± 1.5, and the range of variation of Tc at that time is between 6.9 μs and 8.1 μs. Think

[0051]

[Table 1]

As shown in Table 1, the measured value f of the resonance frequency
The recording head is ranked into A, B, C, D, E, and F according to the value of and the Twd1 of the recording head is determined by predicting the value of the Helmholtz period Tc.

Here, Twd1 is the Helmholtz period Tc
Is larger, Twd1 is smaller, and in rank A where Tc is the largest, it is 3/4 of Tc, and
In the rank F in which c is the smallest, it is determined to be almost equal to Tc.

FIG. 1 is a diagram conceptually showing the effect of this embodiment. Recording head with Tc = 7.0 μs, Tc = 8.0 μ
In the print head of s, Twd1 is set to 6.5 μs, for example.
When the voltage is adjusted to a fixed value and the voltage is adjusted so that the weight of the ink droplet becomes constant, a large difference d ₀ occurs in the ink droplet speed.

According to the present embodiment, Twd1 is 6.0 μs which is 3/4 of Tc in the recording head with Tc = 8.0 μs.
Adjusted to Twd1 for the recording head with Tc = 7.0 μs.
Is adjusted to 7.0 μs which is equal to Tc. This gives T
The printhead with c = 8.0 μs has a high ink drop velocity, and the printhead with Tc = 7.0 μs has a low ink drop velocity.

After that, the ink droplets ejected from the respective heads are ejected with different voltages at two points by a conventional method so that the weight of the ink droplets ejected is constant. The weight is measured, and it is considered that the ink drop weight changes linearly with the voltage, and the voltage is adjusted so that the ink drop weight is appropriate.

In this way, in a plurality of recording heads having variations in Tc, the difference in the speed of the ink droplets for each recording head when the weight of the ink droplets is constant is made small as indicated by d _{1 in} FIG. be able to.

A method of changing the duration Twd1 of the discharge pulse 114 shown in FIG. 5A in this embodiment will be described below. Generally, by using the configuration as shown in FIG. 9, the waveform as shown in FIG. 10 can be generated. In the circuit of FIG. 9, a waveform whose amplitude is almost equal to Vk which is a power supply voltage for generating a driving waveform is formed, and the amplitude is changed by changing only Vk.

Reference numeral 400 denotes a waveform generator, which generates a waveform that is the basis of the drive waveform. The waveform generation device 400 generates a waveform having an amplitude Vk / 3 centered on Vk / 2 as shown in FIG. 10, for example. The output of the waveform generator 400 is connected to the non-inverting terminal of the operational amplifier 301, and the waveform generator 40
The output of 0 is amplified by three times the non-inverting voltage around Vk / 2 and output to the bases of the transistors 302 and 303. Transistors 302 and 303 are push-pull connected transistors for current amplification of the voltage generated by the operational amplifier 301. When the drive waveform rises, the transistor 302 supplies a current according to the load,
When the drive waveform falls, the transistor 303 absorbs current.

The circuit formed by these resistors is shown in FIG. Here, the resistors 304 and 305 have the same size,
If the resistance values are R304, R305, R306, and R307, the circuit of FIG. 11 is equivalent to the circuit of FIG. Therefore, if R307 = 2 × (R304 / 2 + R306), the drive waveform becomes a waveform in which the output of the waveform generating device 400 is tripled with Vk / 2 as the center, as shown in FIG.

The waveform generator 400 is, for example, a digital-analog converter (DAC) as shown in FIG. Here, 401, 402, and 403 are resistors, all of which have the same resistance value, and divide Vk into three equal parts. 404, 4
Reference numeral 05 is an operational amplifier connected to a voltage follower, which outputs a potential divided by the resistors 401, 402, and 403. The resistors 411, 412, ..., 414 are resistors having the same resistance value. Reference numerals 421, 422, ..., 424 denote switches, and one of them is turned on by a control signal.
, And outputs one of the voltages divided by the resistors 411, 412, ..., 414 to the non-inverting terminal of the operational amplifier 431. The operational amplifier 431 is a voltage follower, and the voltage generated by any of the switches 421, 422, ...

Waveform generator 4 using the above DAC
In the configuration of 00, Vk, which is the maximum drive potential when the switch 421 of FIG. 13 is closed, with respect to an arbitrary Vk.
However, when the switch 424 is closed, the minimum drive potential GND is output as the drive wave output.

Even when it is desired to change the falling slope of the discharge pulse 114 in the drive waveform as shown in FIG. 5A, the switches 421, 422 for the time step,
By changing the switching timing of 424, an output waveform having an arbitrary falling slope can be obtained from the waveform generating device 400. In this way, the duration Tw of the discharge pulse 114 of the microdot drive pulse is
d1 can be changed.

[Brief description of drawings]

FIG. 1 is a diagram conceptually showing an effect of an embodiment of the present invention.

FIG. 2 is a block diagram showing the relationship between the printer body and the recording head in the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing the mechanical structure of the recording head in the embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a process of printing with a recording head in an embodiment of the present invention.

FIG. 5A is a drive waveform of microdots in the embodiment of the present invention, and B is a drive waveform of normal dots in the embodiment of the present invention.

FIG. 6 is a diagram showing the relationship between the resonance frequency of the actuator of the recording head and the Helmholtz period in the embodiment of the present invention.

FIG. 7 is a diagram showing how the meniscus of ink vibrates when Twd1 is changed in the embodiment of the present invention.

FIG. 8 is a diagram showing the relationship between Twd1 and the ratio of ink drop velocity to ink drop weight in an example of the present invention.

FIG. 9 is a circuit diagram showing a circuit that outputs a drive waveform according to an embodiment of the present invention.

10 is a diagram showing an example of a waveform output by the circuit of FIG.

11 is a circuit diagram showing a circuit formed by a resistor in the circuit of FIG.

FIG. 12 is a circuit diagram showing a circuit equivalent to the circuit of FIG. 11 in the embodiment of the present invention.

FIG. 13 is a circuit diagram showing a waveform generation device according to an embodiment of the present invention.

[Explanation of symbols]

1 Printer Main Body 2 Recording Head 3 Flexible Flat Cable 10 Recording Head 21 Actuator Unit 22 Flow Path Unit 25 Nozzle Opening 32 Pressure Generation Chamber 33 Piezoelectric Vibrator (Pressure Generation Means) 112 Charging Pulse (Second Contraction Signal) 114 Discharge Pulse ( expansion signal) 116 Charge pulse ( first contraction signal) 118 Discharge pulse

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/205

Claims (5)

(57) [Claims] 1. An ink jet recording head which operates a pressure generating means to contract a pressure generating chamber to eject an ink droplet from a nozzle opening, and a meniscus of ink is largely drawn into the nozzle opening.
Expansion signal for expanding the pressure generating chamber useless, and, bulging
At the timing when the meniscus is pulled in by the tension signal
It is generated, and driving means for outputting a driving signal including a first contraction signal for contracting said pressure generating chamber so as to eject ink droplets from the nozzle opening to said pressure generating means, changing the duration of said inflation signal wherein a means for adjusting the speed of the ink droplets ejected by the contraction signal, the expansion signal by that a vibration period of the meniscus, the serial <br/> specific Helmholtz period for each recording head Tc by respect, an ink jet recording apparatus characterized by reducing the duration of the expansion signal as said peripheral <br/> period Tc is large. 2. The meniscus is raised from the nozzle opening.
A second contraction signal that pressurizes the pressure generating chamber so as to raise it.
2. The ink jet recording apparatus according to claim 1 , wherein the signal is generated before the expansion signal . 3. A Helmholtz method for determining the duration of the expansion signal.
Set between cycle Tc and 3/4 of Helmholtz cycle Tc
The ink jet ink according to claim 1 or 2, characterized in that
Jet recording device. 4. The ink jet according to claim 1 or 2.
A method for adjusting a drive signal of a recording apparatus, comprising: measuring the Helmholtz period Tc; and increasing the Helmholtz period Tc.
Drive signal adjustment method of characteristics and to Louis down <br/> Kujetto type recording apparatus that includes a step of reducing the connection time. 5. A Helmholtz method for determining the duration of the expansion signal.
Set between cycle Tc and 3/4 of Helmholtz cycle Tc
The inkjet according to claim 4, wherein
Method for adjusting drive signal of recording apparatus.