JP2005262639A - Inkjet printing head cleaning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove an adhered ink or foreign matters by an output being as small as possible without breaking a head. <P>SOLUTION: This inkjet printing head cleaning apparatus performs the cleaning of an ink passage by shaking it. The inkjet printing head cleaning apparatus has a frequency setting means which sets the vibration frequency to be a resonance frequency of a member to be cleaned, an amplitude setting means which sets the amplitude of the vibration by the resonance frequency, and a means which can switch a plurality of set values being set by the frequency setting means at respective resonance frequencies for a plurality of the members to be cleaned. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cleaning device for eliminating clogging of an ink jet print head.

  On-demand inkjet print heads that selectively eject ink droplets from the nozzles corresponding to the pixels to be recorded only when dots are recorded. When ink is used, the ink is solidified in the nozzle and the nozzle may be clogged. In recent years, there has been an increasing demand for ejecting ink that tends to aggregate. When such ink is ejected, solid matter aggregated in the ink flow path can be fixed, or foreign matter in the ink can be removed. The filter provided inside the head is clogged, causing a problem in ink ejection.

  As a method for solving such clogging, a cap is applied to the nozzle surface so as to cover the nozzle, and the inside of the cap is decompressed to suck ink and cleaning liquid from the nozzle, and solidified together with the sucked ink and cleaning liquid. There are used a method of removing foreign matter, a method of pressurizing an ink tank, and strongly ejecting ink and cleaning liquid from a nozzle to remove solidified ink and foreign matter. However, in such a method, the pressure escapes to the nozzle that is not clogged, so that a large amount of ink or cleaning liquid is consumed or removed in order to remove the fixed matter from the nozzle that is completely clogged. I can't. Further, it is difficult to remove the solidified ink that is firmly fixed. Furthermore, since the ink flow path is fine and complicated, it is washed to every corner of the ink flow path even when the ink is not fixed, such as when switching to another type of ink. Or it is difficult to replace.

  As another method, there is known a cleaning method in which a head is immersed in an ultrasonic cleaner and a cleaning liquid is passed while vibrating the head (see, for example, Patent Document 1). However, if the vibration is simply performed, the vibration may not be sufficiently transmitted to the ink fixed object located deep in the head. In addition, a fragile member such as an element that generates ink ejection force may be broken or an adhesive part may be peeled off when strong vibration such as an ultrasonic cleaner is applied.

Japanese Patent Laid-Open No. 9-254397

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet print head cleaning apparatus capable of removing solid ink and foreign matters fixed in a head built-in filter, nozzles, and ink flow paths without breaking the head.

  The above object is achieved by adjusting the frequency of vibration applied to the ink jet print head during cleaning to the resonance frequency of the member to be cleaned and different from the resonance frequency of the fragile member.

  According to the present invention, since the member to be cleaned can be vibrated selectively and strongly, the output of the vibrator can be given to the member to be cleaned efficiently, and the fragile member does not vibrate so much. Without breaking, it is possible to effectively remove ink solid matter and foreign matters fixed in the head built-in filter, nozzle, and ink flow path.

  Hereinafter, the present invention will be described based on examples.

  FIG. 1 shows a first embodiment according to the present invention. The ink plate 6 is formed by laminating the nozzle plate 1, the restrictor plate 2, the diaphragm 3, the filter 4, and the housing 5, and the piezoelectric element 7 is bonded to the housing 5 and the diaphragm 3 as an ejection force generating element.

  The vibrator 8 that vibrates the head at the time of cleaning may be in contact with somewhere on the head. A structure in which the vibrator 8 is attached to a head mounting jig (not shown) and the head is vibrated via the head removing jig may be used. A structure in which the head is vibrated via the gap may be used.

  Usually, the vibration frequency of a vibrator used in an ultrasonic cleaner is fixed to a specific frequency, for example, 40 kHz, between 20 kHz and 3 MHz. In the present invention, a vibration is generated by connecting a pulse generator or the like to a driver. The vibration frequency can be arbitrarily set by driving a child, using a vibration frequency variable type ultrasonic cleaner, or using a specially designed vibrator.

  When the head is cleaned, the vibrator 8 is vibrated, and the vibration frequency of the vibrator at that time is set to the resonance frequency of the member to be cleaned. In the head of this embodiment, the nozzle plate has a resonance frequency of 33 kHz, the resonance frequency of the filter is 15 kHz, the resonance frequency of most of the ink flow path is 20 kHz, and the resonance frequency of the piezoelectric element is 370 kHz. In order to remove ink solid matter and foreign matter, the vibrator 8 is vibrated at 33 kHz, and in order to remove ink solid matter and foreign matter clogged in the filter 4, the vibrator 8 is vibrated at 15 kHz, and the ink fixed to the ink flow path. In order to remove foreign matters, the vibrator 8 is vibrated at 20 kHz. By doing so, since the member to be cleaned resonates and vibrates greatly, it is desired to perform cleaning to the same size as when the vibrator 8 is vibrated at a vibration frequency of 40 kHz which is a vibration frequency of a general ultrasonic cleaner. In order to vibrate the member, an output of about 1/2 to 1/10 is sufficient, and as a result, it is possible to set the vibration given to other than the member to be cleaned to be smaller than that when cleaning at 40 kHz, It is possible to prevent breakage of fragile members such as piezoelectric elements that generate ink ejection force.

  There are several methods to measure the resonance frequency of each member of the head. When a sudden shock is applied from the outside, such as driving the vibrator with a rectangular voltage, the vibration generated in each member is laser Doppler. It is easy to obtain by measuring with a measuring instrument.

  A sequence of exciting the head while changing the vibration frequency of the vibrator 8 at a frequency excluding the vicinity of the resonance frequency of 370 kHz of the piezoelectric element and cleaning each member of the head may be included.

  When the cleaning liquid is passed through the head while applying vibration, the cleaning power is further improved. In the case of passing the cleaning liquid, if the air and the cleaning liquid are alternately passed, a large force is generated at the interface between the air and the cleaning liquid.

  In this embodiment, a piezoelectric element is taken as an example of a fragile member. However, the application of the present invention is not limited to an inkjet print head cleaning device using a piezoelectric element, and a specific portion is selectively enlarged. It can be applied to all cases where it is desired to perform cleaning with vibration.

  2 and 3 show a second embodiment according to the present invention. A member that is to be cleaned with a voltage waveform 13 that drives the vibrator 12 that vibrates the inkjet print head 11 at a resonance frequency for each of the plurality of members to be cleaned in accordance with a required vibration amount for a required time. Are applied to the vibrator in the order of. For example, the drive voltage waveform 14 for ink flow path cleaning is 5 minutes, then the drive voltage waveform 15 for filter cleaning is 3 minutes, and finally the drive voltage waveform 16 for nozzle cleaning is 2 minutes. In this embodiment, since the ink solidified matter and foreign matter clogged in the filter are most difficult to remove, the amplitude of vibration is increased. Since the ink flow path is fine and complicated, it takes a long time to vibrate. Note that when vibration is applied for 5 minutes or longer, the effect of the ink solidification or foreign matter re-adherence occurs if the cleaning liquid is not replaced or the cleaning liquid is not passed through, so the effect is weak.

  When the drive voltage waveform 14 for cleaning the ink flow path, the drive voltage waveform 15 for cleaning the filter, and the drive voltage waveform 16 for cleaning the nozzle are added together, a drive voltage waveform 17 for cleaning the ink flow path, the filter, and the nozzle is obtained. When the vibrator 12 is driven with this drive voltage waveform, the ink flow path, the filter, and the nozzle resonate at the same time, and can be oscillated with their required amplitudes, thereby saving the cleaning time. Note that it is not necessary to add up the waveforms of all the members to be cleaned, and cleaning may be performed simultaneously with waveforms added up of a plurality of members.

  Here, although the example about three members was shown, it is applicable to any number of members to be cleaned. Further, the cleaning target for setting the resonance frequency can be set not only for each member but also by the location of the head. In the head of this embodiment, an example is shown in which the resonance frequency is 20 kHz in most of the ink flow path, and the flow path is cleaned by vibration of 20 kHz. However, the flow path is actually narrow. The resonance frequency varies depending on the shape, such as the part or the widened part, and it is effective to clean with various types of frequencies.

  FIG. 4 shows an embodiment of the hit 3 according to the present invention. The element that generates the ink ejection force is the piezoelectric element 21, and the piezoelectric element driving voltage 22 is connected to one of the electrodes, and the driver switch 23 is connected to the other electrode. In the present embodiment, a switch 24 for short-circuiting both electrodes is provided, and the switch 24 is closed while the inkjet print head 26 is vibrated by the vibrator 25 during cleaning. By doing so, even if the ink jet print head 26 vibrates and the vibration is transmitted to the piezoelectric element 21, no potential difference is generated between the two electrodes of the piezoelectric element 21, so the piezoelectric element does not vibrate, and even if a large vibration is transmitted, the piezoelectric element 21 is destroyed. Can escape.

  It can be applied when cleaning an ink jet print head or switching to another type of ink.

It is explanatory drawing which showed the Example of this invention. (Example 1) It is explanatory drawing which showed the Example of this invention. (Example 2) It is a drive voltage waveform figure of a vibrator in the example of the present invention. (Example 2) It is explanatory drawing which showed the Example of this invention. Example 3

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Nozzle plate, 2 ... Restrictor plate, 3 ... Diaphragm, 4 ... Filter, 5 ... Housing, 6 ... Ink flow path, 7 ... Piezoelectric element, 8 ... Vibrator, 11 ... Inkjet print head, 12 ... Vibrator, DESCRIPTION OF SYMBOLS 13 ... Drive voltage waveform of vibrator, 14 ... Drive voltage waveform for ink flow path cleaning, 15 ... Drive voltage waveform for filter cleaning, 16 ... Drive voltage waveform for nozzle cleaning, 17 ... Ink flow path, filter and nozzle Drive voltage waveform for cleaning, 21 ... piezoelectric element, 22 ... piezoelectric element drive voltage, 23 ... driver switch, 24 ... short-circuit switch, 25 ... vibrator, 26 ... inkjet printhead.

Claims (8)

  An ink jet print head cleaning apparatus for cleaning an ink flow path by oscillating the ink jet print head cleaning apparatus, comprising frequency setting means for setting a vibration frequency to a resonance frequency of a member to be cleaned.   2. The inkjet print head cleaning apparatus according to claim 1, further comprising amplitude setting means for setting an amplitude of vibration based on the resonance frequency.   3. The ink jet print head cleaning apparatus according to claim 1, wherein a resonance frequency of a fragile member is not applied during cleaning.   2. An ink jet print head cleaning apparatus according to claim 1, further comprising means capable of switching a plurality of set values set by said frequency setting means to respective resonance frequencies for a plurality of members to be cleaned.   5. The ink jet print head cleaning apparatus according to claim 4, further comprising means capable of switching a plurality of set values set in the amplitude setting means for a plurality of members to be cleaned.   5. The inkjet print head cleaning according to claim 4, further comprising means capable of separately setting a switching time of a set value set by the frequency setting means and the amplitude setting means for the member to be cleaned. apparatus.   The inkjet according to claim 1, further comprising means for vibrating the head with a plurality of overlapping waveforms of the vibration waveforms set by the frequency setting means and the amplitude setting means for each of the plurality of members to be cleaned. Print head cleaning device. 2. An ink jet print head cleaning apparatus according to claim 1, further comprising means for short-circuiting a positive electrode and a negative electrode of a piezoelectric element that generates ink ejection force during cleaning by Shindo.

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