JP2004082718A - Inkjet recorder and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder that prevents clogging of a nozzle opening in a non-recording condition by suppressing a noise due to microvibration of a meniscus. <P>SOLUTION: This inkjet recorder is equipped with a means for vibrating a meniscus of an inkjet head plural times in a time period of non-ejection of ink by each printing signal. The inkjet recorder has the means for vibrating the meniscus plural times in a cycle higher than an audio frequency region in an extent that the ink is not ejected. A burst signal is used as the meniscus vibration driving signal during the recording time period. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inkjet recording apparatus, and more particularly, to an inkjet recording apparatus that vibrates a meniscus formed near an ejection port of an inkjet head, and a technique for preventing clogging of the ejection port.
[0002]
[Prior art]
The on-demand type ink jet recording head is provided with a plurality of nozzle openings and pressure generating chambers which pass through each nozzle opening, and expands and contracts the pressure generating chamber in response to a recording signal to generate ink droplets. It is configured. In such a print head, since new ink is sequentially supplied to the nozzle openings performing the printing operation, there is almost no clogging, but the chance of ejecting ink droplets is extremely low, for example, as in the nozzle openings at the upper and lower ends. If the object is put in a resting state, the clogging is likely to occur.
[0003]
For this reason, when the recording operation is continued for a certain period of time, the recording head is evacuated to the capping means in the non-recording area, where a drive signal is applied to the piezoelectric vibrator, and ink droplets are discharged from all the nozzle openings toward the cap. It has been proposed to perform a so-called flushing operation for forcibly ejecting the liquid.
However, if such measures are taken, the printing operation is interrupted and the printing speed is reduced, and ink consumption is caused.Therefore, the printing device is provided in a pressure generating chamber communicating with a nozzle opening that does not generate ink droplets during the printing operation. A number of techniques have been proposed for applying a minute drive signal to a piezoelectric vibrator to the extent that ink droplets are not ejected to minutely vibrate a meniscus near a nozzle opening to prevent clogging (see Patent Documents 1 and 2). ).
[0004]
[Patent Document 1]
JP-A-57-61576
[Patent Document 2]
U.S. Pat. No. 4,350,989
[0005]
[Problems to be solved by the invention]
According to these, although the number of flushing operations can be reduced to prevent a decrease in recording speed and consumption of ink, there is a problem that audible sound caused by minute vibration becomes noise.
[0006]
The present invention has been made in view of such a problem, and an object of the present invention is to reduce the noise caused by minute vibrations and to reliably prevent the clogging of the nozzle openings by the ink jet recording apparatus. It is to provide.
[0007]
[Means for Solving the Problems]
In order to solve such a problem, the recording apparatus of the present invention includes a driving unit that discharges ink from the discharge port in response to a print signal, and a drive unit that does not discharge ink from the discharge port. A meniscus vibrating means for vibrating the meniscus at a repetition frequency outside the audible frequency range or at a low-frequency sound range.
Further, another configuration of the printing apparatus of the present invention includes a driving unit that discharges ink from the discharge port in accordance with a print signal, and a meniscus near the discharge port of a discharge port that does not discharge ink during a printing period. Meniscus vibrating means for vibrating at a cycle shorter than the ejection cycle for recording.
[0008]
In addition, the ink jet recording method of the present invention includes a step of discharging ink from a discharge port in accordance with a recording signal, and a step of causing a meniscus in the vicinity of the discharge port to be out of the audible frequency range or low when not discharging ink from the discharge port. A meniscus vibration step of vibrating at a repetition frequency in a high frequency sound range.
[0009]
According to another inkjet recording method of the present invention, a step of ejecting ink from an ejection port according to a recording signal, and recording a meniscus near the ejection port of an ejection port that does not eject ink during a recording period. Vibrating at a cycle shorter than the ejection cycle for
[0010]
According to such a configuration, the meniscus minute vibration is performed at a frequency and a cycle that does not cause noise for a person, so that the clogging of the nozzle opening is eliminated and the ink near the nozzle opening is replaced with the ink in the pressure generating chamber. Also, the noise can be reduced.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, details of the present invention will be described based on illustrated embodiments.
[0012]
FIG. 1 shows the structure around the recording of the printer of the present invention. In the drawing, reference numeral 1 denotes a carriage which is connected to a pulse motor 3 via a timing belt 2 and is guided by a guide member 4. The recording paper 5 reciprocates in the paper width direction.
[0013]
An ink jet recording head 6, which will be described later, is attached to the surface of the carriage 1 facing the recording paper, in this embodiment, on the lower surface. The ink jet recording head 6 receives ink supply from the ink cartridge 7 mounted on the upper part of the carriage 1 and discharges ink droplets on the recording paper 5 in accordance with the movement of the carriage 1 to form dots. Record images and text on recording paper.
[0014]
Reference numeral 8 denotes a capping device which is provided in a non-printing area and seals a nozzle opening of the print head 6 during a pause, and receives ink droplets from the print head 6 by a flushing operation performed during a print operation. It is. Note that reference numeral 9 in the drawing denotes a cleaning unit.
[0015]
FIG. 2 shows an embodiment of the recording head 6. In the drawing, reference numeral 10 denotes a first cover plate, which is formed of a thin plate of zirconia having a thickness of about 10 μm, and has a surface on which a pressure generation described later is applied. A drive electrode 12 is formed so as to face the chamber 11. A piezoelectric vibration plate 13 made of PZT or the like is formed on the surface of the drive electrode 12.
[0016]
The pressure generating chamber 11 contracts and expands in response to the flexural vibration of the piezoelectric vibration plate 13, discharges ink full from the nozzle opening 14, and sucks ink in the common ink liquid chamber 16 via the ink supply unit 15. .
[0017]
Reference numeral 17 denotes a spacer which is formed by piercing a through hole in a ceramic plate made of zirconia (ZrO 2) having a thickness suitable for forming the pressure generating chamber 11, for example, 150 μm. The pressure generating chamber 4 is formed by sealing both surfaces of the pressure generating chamber 4 with the first weight body 18.
[0018]
Reference numeral 18 denotes a second heavy body, which communicates with a ceramic plate made of zirconia or the like and connects a later-described ink supply port 15 and the pressure generating chamber 11 to each other, and discharges ink in the pressure generating chamber 11 toward the nozzle opening 14. And is fixed to the other surface of the spacer 17.
[0019]
These members 10, 17, and 18 are formed into a predetermined shape by forming a clay-like ceramic material, laminated, and fired, so as to be integrated into the actuator unit 21 without using an adhesive.
[0020]
Reference numeral 22 denotes an ink supply port forming substrate, which also serves as a fixed substrate for the actuator unit 21 and is made of a metal or ceramic such as non-cast steel having ink resistance so that a connection member for the ink cartridge can be provided. ing.
[0021]
The ink supply port forming substrate 22 is provided with an ink supply port 15 for connecting a common ink liquid chamber 16 and the pressure generation chamber 11 described later on one end side of the pressure generation chamber 11 side. On the other end side, a communication hole 23 that connects the nozzle opening 14 and the ink ejection roller 20 of the actuator unit 21 is provided.
[0022]
Reference numeral 24 denotes a common ink liquid chamber forming substrate, which is formed on a sheet material having a thickness suitable for forming the common ink liquid chamber 16, such as stainless steel having a thickness of, for example, 150 μm. A corresponding through hole and an encounter hole 26 for connecting the nozzle opening 14 of the nozzle plate 25 and the ink discharge port 20 are formed.
[0023]
The ink supply port forming substrate 22, the common ink liquid chamber forming substrate 24, and the nozzle plate 25 are each provided with an adhesive layer S. made of a heat welding film, an adhesive or the like. They are grouped together in the channel unit 27 by S.
[0024]
A recording head is formed by fixing the actuator unit 1 to the surface of the ink supply port forming substrate 22 of the flow path unit 27 with an adhesive.
[0025]
With such a configuration, when the piezoelectric vibrator 13 is charged and the piezoelectric vibrator 13 bends, the pressure generating chamber 11 contracts. As a result, the ink in the pressure generating chamber 11 is pressurized and ejected from the nozzle openings 14 as ink droplets, thereby forming dots for recording.
[0026]
When the electric charge of the piezoelectric vibrator 13 is discharged after a lapse of a predetermined time, the piezoelectric vibrator 13 returns to the original state. As a result, the pressure generating chamber 11 expands, the ink in the common ink liquid chamber 16 flows into the pressure generating chamber 11 via the ink supply port 15, and the ink for the next printing is supplied to the pressure generating chamber 11. Is done.
[0027]
On the other hand, when the piezoelectric vibrator 13 is charged with a very small voltage that does not cause the piezoelectric vibrator 13 to eject ink droplets and the piezoelectric vibrator 13 is slightly bent, the pressure generating chamber 11 also slightly contracts. As a result, the meniscus near the nozzle opening 14 is pushed out to the nozzle opening 14 by a very small amount.
[0028]
Next, when the electric charge of the piezoelectric vibrator 13 is discharged and returned to the original state, the pressure generating chamber 11 expands a small amount, and the meniscus pushed to the nozzle opening side is returned to the pressure generating chamber 11 side.
[0029]
When the piezoelectric vibrator 13 is flexed by a minute amount in the same cycle as the recording timing or returned to the original state, the meniscus near the nozzle opening also vibrates by a minute amount, and the ink near the nozzle opening is pressurized. The ink is replaced with the ink in the generation chamber 11 to help prevent day clogging.
[0030]
FIG. 3 shows an embodiment of a control device for driving the recording head 6 described above. In the drawing, reference numeral 30 denotes a control means which receives a recording command signal or recording data from a host and generates a driving signal described later. The circuit 31, the head drive circuit 32, and the carriage drive circuit 33 are controlled to execute a printing operation, and at the same time, flushing is performed at the capping position or minute vibration of the meniscus described above is performed based on time data of a printing timer 36 described later. For controlling the magnitude, the application cycle and the time of the second and third drive signals.
[0031]
The drive signal generation circuit 31 is configured to generate a trapezoidal first drive signal (FIG. 4 (a)) having a voltage value VH required to eject ink droplets from the nozzle openings 11. The first drive signal has its duration Tw set to match the natural oscillation period of the pressure generating chamber 13. This makes it possible to effectively convert the displacement of the piezoelectric vibrator 13 into the movement of the meniscus.
[0032]
The drive circuit 32 applies the ejection drive signal (FIG. 4A) of the drive signal generation circuit 31 to the piezoelectric vibrator 13 corresponding to the print data, and outputs the ejection drive signal in the standby state and before the start of printing. A drive signal (FIG. 4B) of a meniscus minute vibration that does not eject about 1/2 of the ink is applied at a repetition frequency higher or lower than the audible frequency range (20 to 20 kHz). ing. That is, the vibration is performed at a frequency outside the audible frequency range. Alternatively, in consideration of the loudness curve, the vibrator is vibrated at a repetition frequency in a low-frequency sound region (20 to 100 Hz) in which the auditory sensitivity characteristic is reduced.
[0033]
Reference numeral 35 stores data for adjusting the voltage value and gradient of the drive signal in accordance with the temperature, and data for adjusting the level of the drive signal in accordance with the amount of ink consumed during printing. . Reference numeral 36 denotes a recording timer for measuring the duration of the recording operation, which is started at the start of the recording operation and reset by the flushing operation.
[0034]
Reference numeral 37 denotes a recording amount counter which counts the number of dots recorded during recording to detect the amount of ink consumed. In the drawing, reference numeral 38 denotes a temperature detecting means for detecting the temperature around the recording head.
[0035]
FIG. 5 shows an embodiment of the above-described drive signal generating circuit 31. In the figure, reference numeral 40 denotes a one-shot multivibrator for converting a timing signal from an external device into a pulse signal having a constant width, which is synchronized with the timing signal. And outputs a positive signal and a negative signal from the output terminal. One terminal is connected to the base of an NPN transistor 41, to which a PNP transistor 42 is connected. When a timing signal is input, the capacitor 43 is supplied with a constant current r until the power supply voltage VH is reached. Charge.
[0036]
An NPN transistor 48 is connected to the other terminal of the one-shot multivibrator 40, and when the timing signal is switched, the transistor 42 is turned off and the transistor 48 is turned on to charge the capacitor 43. Discharge is performed at a constant current f until the charged electric charge drops to substantially zero volt.
[0037]
As a result, as shown in FIG. 4A, the terminal voltage of the capacitor 43 has a region where the terminal voltage rises with a constant gradient α, a saturation region where a constant value is maintained, and a region where the terminal voltage drops with a constant gradient β. .. Have a trapezoidal waveform, are current-amplified by the transistors 49 and 50, and are output from the terminal 51 to each of the piezoelectric vibrators 13, 13, 13,... As a source drive signal.
[0038]
Next, the operation of the above-described drive signal generation circuit 31 will be described. All switching transistors T, T.T. ... Are turned on only for a short time. As a result, all the piezoelectric vibrators 13, 13, 13 are charged by the voltage from the drive signal generating circuit 31, but the pulse signal falls on the way, so that the switching transistor TT. Are turned off, and charging ends at a voltage determined by the time up to this point.
[0039]
For this reason, by controlling the charging time, it becomes possible to generate the drive signal VH / 2 suitable for causing a minute vibration during the suspension of recording or during the recording period.
[0040]
As a result, as shown in FIG. 4 (mouth), the piezoelectric vibrator 13 has the same gradient α as that at the time of recording, and uses a voltage as small as about の of the drive signal VH for performing ink droplet ejection. A flexural vibration that does not allow the ink droplet to fly from the nozzle opening 14 is caused, and the pressure generating chamber 11 is minutely expanded and contracted to give a minute vibration to the meniscus near the nozzle opening 14.
[0041]
Since the period Tl is a repetition period (frequency) outside the audible frequency region (20 to 20 kHz) or a repetition period (frequency) of the low-frequency sound region (20 to 100 Hz), the time when a minute vibration is given to the meniscus Clogging of the nozzle opening in the non-printing state can be prevented while reducing noise.
[0042]
On the other hand, when a print signal is input from the control means 30, the transistors 42 and 48 are turned on and off to output a trapezoidal voltage, that is, a first drive signal. Since the switching transistors T, T, T,... Connected to the piezoelectric vibrator 13 to be recorded are turned on by the drive circuit 32 to be described later, up to the voltage VH by the drive signal. It will be charged.
[0043]
As a result, the drive signal generated by the drive signal generation circuit 31 flows into the piezoelectric vibrator 13 and charges the piezoelectric vibrator 13 with a constant current. .., Which discharge ink droplets for recording, bend to the pressure generating chamber 11 side to contract the pressure generating chamber 11, and the ink droplets are discharged from the nozzle opening 14. Is discharged.
[0044]
After a certain period of time, the transistor 48 is turned on and the capacitor 43 is discharged. As a result, the piezoelectric vibrators 13.13, 13... The chamber 11 expands and the ink in the common ink liquid chamber 16 flows into the pressure generating chamber 11.
[0045]
When the recording head moves to the non-recording area, a driving signal of a minute vibration of about 1/2 of the driving signal of the ejection is applied to the piezoelectric vibrator 13 and charged and discharged by this voltage, and Is performed.
[0046]
The operation of the device configured as described above will be described with reference to the timing chart of FIG. When the recording signal is input and the carriage 1 starts moving from the standby state in which the recording head 6 is not sealed by the capping device 8 in the pause state, the control unit 30 accelerates the carriage 1 toward the recordable speed. When the micro-vibration is repeated a plurality of times, for example, three or more times immediately before the recording speed is reached, and the micro-vibration is applied at a frequency higher than the audible frequency range, the burst is recorded at the same interval as the ejection cycle at the time of recording. Is repeated a plurality of times, for example, five times or more. As a result, the ink in the vicinity of the nozzle opening is replaced with the ink in the pressure generating chamber 11 where the viscosity has not increased, and the ink can be reliably ejected during recording.
[0047]
Immediately before the recording operation is performed in this manner, for example, the output of the driving signal of the minute vibration is stopped at least one ejection cycle before the input of the recording signal, and the driving signal generation circuit 31 is required to eject the ink droplet. Prepare a system to output level signals. When the carriage 1 reaches the printing speed and print data is input, the print timer 36 is started to wait for input of print data.
[0048]
When a print signal is input in this state, the printhead 6 is scanned by the carriage 1 in the width direction of the print sheet 5 and the piezoelectric vibrator 13 to be printed is deflected by the rising voltage of the first drive signal. The generation chamber 13 is contracted to eject ink droplets from the nozzle openings 14. When the predetermined time has elapsed, the piezoelectric vibrator 13 is returned to the original state by the drop voltage of the ejection drive signal, the pressure generation chamber 13 is expanded, and the ink in the common ink liquid chamber 16 is transferred to the pressure generation chamber 11. Let it flow in.
[0049]
During this printing period, not all nozzles discharge, and some nozzles may not perform printing for a while. When minute vibration is applied at a frequency higher than the audible frequency range in order to prevent such nozzle clogging, the above-described minute signal burst is applied to the non-ejection nozzle at the same timing as the ejection drive signal.
[0050]
When printing for one scan of the carriage 1 is completed and the application of the ejection drive signal is stopped, the print head 6 returns to the same state as the above-described standby state. After that, the carriage 1 is decelerated and the scanning direction is reversed. Then, re-acceleration is performed to perform a printing operation for the next scanning. During this time, the meniscus is minutely vibrated again in the same manner as described above to prevent the nozzle opening 14 from being clogged.
[0051]
This scanning and printing cycle is repeated until there is no more print data from the host, and printing is performed.
[0052]
When the count of the recording timer 36 reaches a predetermined time, for example, 10 seconds, during a series of recording, the control means 30 moves the recording head 6 to a flushing position, that is, a position facing the capping device 8, and a predetermined number, for example, several thousand A periodic flushing operation for discharging ink droplets for dots is executed. When the flushing operation is completed, the recording timer 36 is reset to execute the clocking operation again, and the recording operation is started again by the above-described steps.
[0053]
Thereafter, every time the recording timer 36 counts a predetermined time, a periodic flushing operation is executed to forcibly eject ink from all the nozzle openings 14 to prevent clogging.
[0054]
In the above-described embodiment, the level of the drive signal of the minute vibration applied to the piezoelectric vibrator 13 in order to make the meniscus minutely vibrate during the idle period in the non-printing area is maintained at a constant value VH / 2. Based on the data from the recording amount counter 37, the recording head 6 detects the recording area and the amount of ink ejected by regular flushing. If the amount of ejected ink is large, the voltage value of the drive signal of the minute vibration is reduced. In addition, when the number is small, the voltage value is increased within a range in which ink droplets are not ejected, and a minute vibration is performed in consideration of the viscosity of the ink in the pressure generating chamber 11. Can be surely prevented from clogging while minimizing the burden on the user.
[0055]
The setting of the level of the driving signal of the minute vibration corresponding to the ejection amount of the ink droplet during the recording period is performed by storing the relationship between the ejection amount and the voltage value in the recording unit 35 in advance, and setting the ejection amount data of the recording amount power counter 37. Can be easily realized by reading the voltage value corresponding to.
[0056]
Further, since the viscosity of the ink greatly changes depending on the temperature, when a low-voltage signal is applied to the piezoelectric vibrator 13 to cause the meniscus to perform a minute vibration, the amplitude value of the minute vibration is greatly changed by the temperature. .
[0057]
In order to solve such a problem, it is conceivable to adjust the voltage level. However, since the charging time needs to be controlled, the circuit configuration becomes complicated. For this reason, while maintaining the voltage value of the drive signal of the minute vibration constant (W / 2), only the rising gradient and the falling gradient are adjusted in accordance with the environmental temperature.
[0058]
That is, for a room temperature (25 ° C.), the rising gradient α is 4 V / μsec, and for the falling gradient β is 6.7 V / μsec, and for a low temperature of 10 ° C., the rising gradient α1 is 5 V / μsec. Second, the falling slope β1 is 8.4 V / μsec, and for a high temperature, the rising slope α2 is 3 V / μsec, and the falling slope β2 is 5 V / μsec. The return speed was increased as the temperature decreased, to assist the movement of the ink whose viscosity was increased at a low temperature.
[0059]
Adjustment of the rising slopes α, α1, α2 and the falling slopes β, β1, β2 at these temperatures is performed by storing data indicating the relationship between the temperature and the slopes α, α1, α2, β, β1, β2 in the storage means 35 in advance. Is stored, and is read out by the temperature signal from the temperature detecting means 38, so that it can be easily realized.
[0060]
According to this embodiment, the level of the audible sound caused by the minute vibration can be reduced to one-sixth of the number of sets, and the noise of the recording apparatus can be reduced. In the above-described embodiment, the release of the pause state is detected by the movement of the carriage. However, the same operation can be achieved by detecting and detecting the input of the recording signal from the external device.
[0061]
FIG. 7 shows another embodiment of a recording head using a piezoelectric vibrator in a longitudinal vibration mode to which the present invention can be applied. In the drawing, reference numeral 71 denotes a diaphragm, and a tip of a piezoelectric vibrator 72 is shown. The flow path unit 75 is formed of a thin plate that is elastically deformed by contact with the nozzle plate 74 and is fixed to the nozzle plate 74 in a liquid-tight manner with the flow path forming plate 73 interposed therebetween.
[0062]
Reference numeral 76 denotes a base, which has a housing chamber 77 for vibratingly accommodating the piezoelectric vibrator 72 and an opening 78 for supporting the flow path unit 75, and the tip of the piezoelectric vibrator 72 abuts on the island portion 71 a of the diaphragm 71. The recording head is configured by fixing the flow path unit 75 so as to make contact therewith.
[0063]
With such a configuration, when the piezoelectric vibrator 72 is charged and contracts, the pressure generating chamber 83 expands. Accordingly, the ink in the common ink liquid chambers 80 flows into the pressure generating chamber 83 via the ink supply units 81 and 81.
[0064]
When the electric charge of the piezoelectric vibrator 72 is discharged after a lapse of a predetermined time and the piezoelectric vibrator 72 returns to the original state, the pressure generating chamber 83 contracts, the ink in the pressure generating chamber 83 is compressed, and the ink from the nozzle opening 82 is compressed. The ink is ejected as droplets to form dots on recording paper.
[0065]
When a small pulse is applied to the piezoelectric vibrator 72 so as not to cause ink droplets to be ejected and the piezoelectric vibrator 72 contracts by a very small amount, the pressure generating chamber 83 also expands a little, so that the meniscus near the nozzle opening 82 generates pressure. It is drawn into the chamber 83 side. Next, when the piezoelectric vibrator 72 is returned to the original state, the pressure generating chamber 83 contracts and the meniscus is slightly pushed back to the nozzle opening 82 side.
[0066]
When the piezoelectric vibrator 72 expands and contracts by a very small amount in the same cycle as the recording timing, the meniscus near the nozzle opening 82 also vibrates by a very small amount. It is possible to prevent clogging of the nozzle opening by replacing the ink with the ink of No. 83.
[0067]
In the above-described embodiment, the printing operation of the recording head is performed by applying the third drive signal and then applying the first drive signal. However, after applying the first drive signal, The same operation is achieved by applying the third drive signal.
[0068]
In addition, an ink jet recording head having a pressure generating chamber formed by a nozzle plate having a nozzle opening formed therein and a vibration plate deformed by displacement of a piezoelectric vibrator, and a trapezoidal shape for discharging ink droplets from the nozzle opening. The first drive signal, a drive signal generating means for generating a drive signal of minute vibration for vibrating the meniscus to such an extent that ink droplets are not ejected from the nozzle opening, and one print cycle when the print head is present in the print area. A first mode in which a drive signal of minute vibration is continuously applied to the piezoelectric vibrator, and a drive signal of minute vibration continuously for a longer time than the application time in the first mode immediately before recording is started. And a second mode in which the second mode is applied to the piezoelectric vibrator. In the idle state, the meniscus is vibrated for a fixed period of time for a fixed period of time shorter than the period during which no clogging of the nozzle opening occurs, thereby reducing the number of vibrations of the piezoelectric vibrator as much as possible and reducing the fatigue and noise of the piezoelectric vibrator. The clogging of the nozzle opening is prevented while clogging is prevented.Also, immediately before the start of recording, minute vibration is continuously performed to reliably eliminate the clogging of the nozzle opening, and the ink near the nozzle opening is replaced with the ink in the pressure generating chamber having a low viscosity. By performing the replacement, the recording operation can be guaranteed.
In the above-described embodiment, the description has been made using the piezoelectric element as the recording element for ejecting the ink. However, the present invention is not limited to this, and a heating element that applies thermal energy to the ink to generate bubbles may be used. Further, the description has been made using a piezoelectric element as a means for vibrating the meniscus, but the present invention is not limited to this, and a heating element that gives bubbles to ink to generate bubbles may be used, and may also be used as a recording element for discharging ink. Good. As a means for vibrating the meniscus, a means for causing deformation of the pressure chamber using electrostatic force or a vibrator for micro vibration may be used.
[0069]
Next, a case where a piezoelectric element of a slip deformation mode is used will be described.
[0070]
FIG. 8 shows an embodiment of a recording head using a piezoelectric vibrator in a slip deformation mode to which the present invention can be applied. In the drawing, a recording head 181 has a bottom 183 extending rearward in parallel from a nozzle plate 182. have. The bottom portion 183 is formed by polarizing and processing a piezo material, and has grooves formed by scribing. The flow path 184 corresponding to the groove is long and narrow with a rectangular cross section, and has a side wall 185 extending in the longitudinal direction. The side wall 185 extends over the entire length of the flow path. Electrodes are formed on the side surface of the side wall 185 by plating. When a voltage is applied to the electrodes on both sides of the side wall 185, an electric field is applied to the polarized piezo material, and the side wall 185 slides and deforms perpendicularly to the flow channel axis so that droplets are ejected from the nozzle. Then, the ink pressure in the flow path is changed. The flow path 184 is covered with a cover 186, and is connected to a manifold 187, which is a groove formed in the cover 186, at an end remote from the nozzle, and is connected to an ink reservoir (not shown). An electrical circuit (not shown) that deforms the side wall 185 is made in the driver IC 188 on the bottom 183. By controlling the application of pressure to a number of parallel flow paths 184 by the driver IC 188, on-demand ink ejection from a number of nozzles is achieved at the same time.
[0071]
At this time, when a small voltage that does not cause ink droplets to be ejected is applied to the side wall 185 to expand the flow path 184 by a very small amount, a meniscus near the nozzle opening 189 formed by drilling on the nozzle plate 182 is drawn. Then, when the voltage is returned to the original state, the meniscus is slightly pushed back to the exit side of the nozzle opening 189.
[0072]
When the side wall 185 is minutely deformed in synchronization with the printing timing in this manner, the meniscus near the nozzle opening 189 also vibrates by a minute amount, so that the ink near the nozzle opening is replaced with the ink in the flow path 184 as in the above-described embodiment. It is possible to prevent clogging of the nozzle opening by replacement.
[0073]
Next, a description will be given of a device using an electrostatic force as a means for causing minute vibration.
[0074]
FIG. 9 shows an embodiment of a recording head using pressurization by deformation of a pressure chamber using electrostatic force to which the present invention can be applied. In the drawing, the inkjet head has a structure described in detail below. It has a laminated structure in which three substrates 191, 192, and 193 are overlapped and joined. The intermediate substrate 192 is, for example, a silicon substrate, and communicates with a plurality of nozzle grooves formed at equal intervals in parallel from one end on the surface of the substrate 192 so as to form the plurality of nozzle holes 194 and the respective nozzle grooves. A concave portion that forms a discharge chamber 196 having a bottom wall as a vibration plate 195, a narrow groove provided at a rear portion of the concave portion for forming an orifice 197, and an ink inlet, and each discharge chamber 196. Has a concave portion that constitutes a common ink liquid chamber 198 for supplying ink to the ink tank. In addition, a concave portion which forms a vibration chamber 199 for mounting an electrode described later is provided below the vibration plate 195. The upper substrate 191 bonded to the upper surface of the intermediate substrate 192 is made of, for example, glass or plastic, and the nozzle hole 194, the discharge chamber 196, the orifice 197, and the ink liquid chamber 198 are formed by bonding the upper substrate 191. . Then, an ink supply port 193 communicating with the ink liquid chamber 198 is formed in the upper substrate 191. The ink supply port 193 is connected via a connection pipe 200 to an ink tank (not shown). The lower substrate 193 joined to the lower surface of the intermediate substrate 192 is made of, for example, glass or plastic. An electrode 201 is formed at each corresponding position. The electrode 201 has a lead 202 and a terminal 203. Further, the entire electrode 201 and the lead 202 except for the terminal 203 are covered with an insulating film (not shown). A lead wire is bonded to each terminal section 203. Further, an oscillation circuit 204 is connected between the intermediate substrate 192 and the terminal portion 203 of the electrode 201, thereby forming an ink jet head. Ink is supplied from an ink tank (not shown) into the intermediate substrate 192 through an ink supply port 193, and fills an ink liquid chamber 198, a discharge chamber 196, and the like. 205 is an ink droplet ejected from the nozzle hole 194, and 206 is a recording paper.
[0075]
Next, the operation of this embodiment will be described. When a pulse voltage is applied to the electrode 201 by the oscillation circuit 204 and the surface of the electrode 201 is charged to a positive potential, the lower surface of the corresponding diaphragm 195 is charged to a negative potential. Therefore, the vibration plate 195 is bent downward due to the attraction of the static electricity. Next, when the electrode 201 is turned off, the diaphragm 195 is restored. Therefore, the pressure in the discharge chamber 196 rises rapidly, and the ink droplet 205 is discharged from the nozzle hole 194 toward the recording paper 206. When the vibration plate 195 is bent downward, ink is supplied from the ink liquid chamber 198 into the ejection chamber 196 through the orifice 197. As the oscillating circuit 26, one that turns ON / OFF between 0V and + voltage, an AC power supply, or the like is used as described above. In recording, an electric pulse to be applied to the electrode 201 of each nozzle hole 194 may be controlled.
[0076]
At this time, when the diaphragm 195 is deformed by a small amount by applying a small voltage to the electrode 201 so that no ink droplet is ejected, the meniscus near the nozzle hole 194 is drawn. Then, when the voltage is returned to the original state, the meniscus is slightly pushed back to the exit side of the nozzle hole 194.
[0077]
When the diaphragm 195 is deformed by a minute amount in synchronization with the printing timing in this manner, the meniscus near the nozzle hole 194 also vibrates by a minute amount, so that the ink near the nozzle opening is discharged from the discharge chamber 196 in the same manner as in the above-described embodiment. The nozzle opening can be prevented from being clogged by being replaced with ink.
[0078]
Next, a case where the means for causing minute vibration is a vibrator will be described.
[0079]
FIGS. 10 and 11 respectively show a vibrator for minute vibration, in which the present invention is applicable, a vibrator for minute vibration, and a recording head in which the ink discharging means uses pressure by bubbling by a heating element. FIGS. 10 and 11 show an embodiment of a recording head in which a vibrating means and an ink discharging means use pressure by foaming by a heating element. In FIGS. 10 and 11, an ink jet head 155 has a plurality of heaters 102 for heating ink. It is roughly composed of a heater board 104 which is a formed substrate, and a top plate 106 which is put on the heater board 104. A plurality of discharge ports (nozzles) 108 are formed in the top plate 106, and a tunnel-like liquid path 110 communicating with the discharge ports 108 is formed behind the discharge ports 108. Each liquid channel 110 is separated from an adjacent liquid channel by a partition 112. Each liquid passage 110 is commonly connected to one ink liquid chamber 114 at the rear thereof, and ink is supplied to the ink liquid chamber 114 through an ink supply port 116. The liquid is supplied to each liquid channel 110.
[0080]
The heater board 104 and the top plate 106 are aligned so that each heater 102 comes to a position corresponding to each liquid channel 110, and assembled in a state as shown in FIG. Although only two heaters 102 are shown in FIG. 10, the heaters 102 are arranged one by one corresponding to each of the liquid paths 110. When a predetermined drive pulse is supplied to the heater 102 in the assembled state as shown in FIG. 10, film boiling occurs in the ink on the heater 102 to form bubbles. It is extruded from 108 and discharged. Therefore, it is possible to adjust the size of the bubble by controlling the driving pulse applied to the heater 102, for example, by controlling the magnitude of the electric power, and it is possible to freely control the volume of the ink ejected from the ejection port. it can.
[0081]
In FIG. 10, at this time, if the ink liquid chamber 114 is expanded and contracted by a very small amount by applying a vibration that does not cause the ink droplets to be ejected by the microvibrator vibrator 101, the meniscus near the ejection port 108 may be drawn. It is pushed back.
[0082]
When the vibrator 101 is vibrated by a minute amount in synchronization with the printing timing in this manner, the meniscus near the ejection port 108 also vibrates by a minute amount. And the nozzle opening can be prevented from being clogged.
[0083]
In FIG. 11, at this time, by controlling the driving pulse applied to the heater 102, for example, by controlling the magnitude of the electric power, if a minute bubble is generated so as not to eject the ink droplet, the meniscus near the ejection port 108 may be pushed back. Or get pulled in.
[0084]
When such microbubbles are generated in synchronization with the printing timing, the meniscus near the discharge port 108 also vibrates by a very small amount. Therefore, the ink near the nozzle opening is replaced with the ink in the liquid path 110 as in the above-described embodiment. Thus, clogging of the nozzle opening can be prevented.
[0085]
【The invention's effect】
Since the meniscus micro-vibration is performed at a frequency and cycle that does not cause noise for humans, noise can be reduced even when the clogging of the nozzle opening is eliminated and ink near the nozzle opening is replaced with ink in the pressure generating chamber. be able to.
[Brief description of the drawings]
FIG. 1 is a diagram showing one embodiment of an ink jet recording apparatus to which the present invention is applied.
FIG. 2 is a cross-sectional view showing one embodiment of an ink jet recording head.
FIG. 3 is a block diagram of an apparatus showing one embodiment of the present invention.
FIGS. 4A and 4B are waveform diagrams showing first and second drive signals applied to a piezoelectric vibrator, respectively.
FIG. 5 is a diagram showing one embodiment of a drive signal generation circuit.
FIG. 6 is a diagram illustrating a drive signal applied to a piezoelectric vibrator corresponding to a movement of a carriage.
FIG. 7 is a diagram showing an embodiment of another type of recording head to which the present invention can be applied.
FIG. 8 is a diagram showing an embodiment of a recording head of another type (slip deformation mode) to which the present invention can be applied.
FIG. 9 is a diagram showing an embodiment of a recording head of another type (electrostatic force) to which the present invention can be applied.
FIG. 10 is a diagram showing an embodiment of another type (a micro-vibration vibrator) to which the present invention can be applied.
FIG. 11 is a diagram showing an embodiment of a recording head of another type (BJ) to which the present invention can be applied.
[Explanation of symbols]
1 carriage
2 Timing belt
3 pulse motor
4 Guide member
5 Recording paper
6 Recording head
7 Ink cartridge
8 Capping device
9 Cleaning means
10 First lid plate
11 Pressure generating chamber
12 Drive electrode
13 Piezoelectric diaphragm
14 Nozzle opening
15 Ink supply port
16 Ink liquid chamber
17 Spacer
18 Second heavy body
19 Communication hole
20 Ink ejection port
21 Actuator unit
22 Ink supply port forming substrate
23 communication hole
24 Ink liquid chamber forming substrate
25 Nozzle plate
26 Encounter Hole
27 Channel unit
30 control means
31 Drive signal generation circuit
32 Head drive circuit
33 Carriage drive circuit
35 Micro vibration storage means
36 Recording timer
37 Recording amount counter
38 Temperature detection means

Claims (16)

An inkjet recording apparatus that performs recording by ejecting ink from an ejection port of an inkjet head,
Driving means for discharging ink from the discharge port in accordance with a recording signal;
An ink jet recording apparatus comprising: a meniscus vibrating means for vibrating a meniscus near the discharge port at a repetition frequency in an audible frequency range or a low-frequency sound range when ink is not discharged from the discharge port. . The inkjet recording apparatus according to claim 1, wherein the repetition frequency outside the audible frequency range is a frequency higher than 20 KHz. The inkjet recording apparatus according to claim 1, wherein the repetition frequency outside the audible frequency range is a frequency lower than 20 Hz. The apparatus according to claim 1, wherein the repetition frequency of the low-frequency sound region is a frequency of 20 to 100 Hz. 5. The ink jet recording apparatus according to claim 1, wherein the vibration of the meniscus is given between recordings in which the ink is ejected. 6. An ink jet recording apparatus according to claim 1, wherein said means for causing vibration is an electrostrictive element. 6. An ink jet recording apparatus according to claim 1, wherein said means for causing vibration is a heating element for causing foaming of the ink. 6. An ink jet recording apparatus according to claim 1, wherein said means for causing vibration is means for causing deformation of a pressure chamber using electrostatic force. 6. The ink jet recording apparatus according to claim 1, wherein the means for generating vibration is a vibrator for minute vibration. An inkjet recording apparatus that performs recording by ejecting ink from an ejection port of an inkjet head,
Driving means for discharging ink from the discharge port in accordance with a recording signal;
An ink jet recording apparatus comprising: a meniscus vibrating means for vibrating a meniscus in the vicinity of a discharge port of a discharge port which does not discharge ink during a recording period at a period shorter than a discharge period for recording. The ink jet recording apparatus according to claim 10, wherein the means for causing the vibration is an electrostrictive element. 11. The ink jet recording apparatus according to claim 10, wherein the means for causing the vibration is a heating element for causing foaming of the ink. The ink jet recording apparatus according to claim 10, wherein the means for causing the vibration is a means for causing a deformation of the pressure chamber using an electrostatic force. The ink jet recording apparatus according to claim 10, wherein the means for generating the vibration is a vibrator for minute vibration. An inkjet recording method for performing recording by ejecting ink from an ejection port of an inkjet head,
Discharging ink from the discharge port in accordance with a recording signal;
A meniscus vibrating step of vibrating a meniscus in the vicinity of the discharge port at a repetition frequency of an audible frequency range or a low-frequency sound range when ink is not discharged from the discharge port. . An inkjet recording method for performing recording by ejecting ink from an ejection port of an inkjet head,
Discharging ink from the discharge port in accordance with a recording signal;
A meniscus vibration step of vibrating a meniscus near an ejection port of an ejection port that does not eject ink during a recording period at a cycle shorter than an ejection cycle for recording.

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