JP2007090585A - Inkjet head cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To circulate cleaning liquid smoothly by preventing the cleaning liquid from flowing over the upstream side channel of a nozzle even in case of an inkjet head with a large number of clogged nozzles. <P>SOLUTION: The inkjet head cleaning device has a first passage for supplying cleaning liquid from a cleaning liquid tank 20 to an ink supply port 34 and delivering the cleaning liquid from a nozzle 54, and a second passage having an opening/closing channel for supplying the cleaning liquid from the cleaning liquid tank 20 to the ink supply port 34 of an inkjet head 4, delivering the cleaning liquid from the nozzle 54, receiving the cleaning liquid in the inkjet head 4 from the second ink supply port 40 of the inkjet head 4 and introducing the cleaning liquid in the inkjet head 4 into a head cleaning container 6. Cleaning is performed through the first passage when a small number of nozzles 54 in the inkjet head 4 are clogged, and the cleaning liquid is supplied into the inkjet head through the second passage when a large number of nozzles 54 in the inkjet head 4 to be cleaned are clogged. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet head cleaning apparatus for immersing an inkjet head in a cleaning liquid, circulating the cleaning liquid to remove clogging of nozzles of the inkjet head with the cleaning liquid, and normalizing an ink ejection function of the inkjet head.

In recent years, inkjet heads having a large number of ink ejection nozzles have been developed so as to be able to cope with high-resolution detailed images and to cope with enlargement of the printing range and shortening of the printing time. Such a head with a large number of nozzles is still expensive, and if the ink cannot be ejected from the nozzles due to nozzle clogging, which is also the fate of the inkjet head, the head cannot be used, resulting in a great economic loss.
In inkjet printing, images are created by ejecting ink from the nozzles. If the nozzles are clogged to some extent by software correction, it is possible to deal with mask processing etc. without using that part. Although possible, it is not a basic solution.
Therefore, conventionally, an apparatus for cleaning an ink jet head by immersing it in a cleaning liquid and circulating it has been proposed (see, for example, Patent Documents 1 and 2).
JP 63-122546 A JP 2004-358667 A

In such an apparatus, for example, the cleaning liquid is pumped up from the tank, injected into the ink jet head, ejected from the nozzle of the ink jet head, discharged into the cleaning liquid container, and then sucked up again, returned to the tank through the filter, and sucked up. If the head nozzle is not clogged, the cleaning liquid will flow out from the nozzle relatively normally and will circulate without problems, but if the nozzle is clogged more than expected, There is a possibility that the cleaning liquid injected into the head may overflow without properly circulating.
The present invention aims to solve the above problems.

In order to achieve the above object, the present invention is directed to injecting a cleaning liquid in a cleaning liquid tank into an ink jet head disposed in a head cleaning container by a pump, and supplying the cleaning liquid discharged from a nozzle of the ink jet head into the head cleaning container. Ink jet having a flow path through which the stored cleaning liquid is returned to the cleaning liquid tank by a pump, and the cleaning liquid entering from the ink supply port of the inkjet head is circulated through the cleaning liquid tank. A head cleaning device, wherein a cleaning liquid is supplied from the cleaning liquid tank to at least one ink supply port of the inkjet head, and the cleaning liquid flows out from the nozzle of the inkjet head, and the cleaning liquid is supplied from the cleaning liquid tank. Inkjet head Supplying to at least one ink supply port and allowing the cleaning liquid to flow out from the nozzle of the inkjet head, while receiving the cleaning liquid in the inkjet head from the other second ink supply port of the inkjet head, cleaning liquid in the inkjet head And a second path having an openable and closable flow path that guides the ink into the head cleaning container. When the nozzles of the inkjet head are not clogged, the inkjet path is cleaned by the first path and cleaned. When a large number of nozzles are clogged, washing is performed in the second path so that the cleaning liquid supplied into the inkjet head does not overflow from the flow path upstream of the nozzles due to clogging of the nozzles. .
In the present invention, a filtration device is provided in a flow path through which the cleaning liquid circulates.
Also, the present invention provides an openable and closable flow path that receives the cleaning liquid in the inkjet head from the other second ink supply port of the inkjet head and guides the cleaning liquid in the inkjet head into the head cleaning container. A first portion that is connected to the other second ink supply port of the inkjet head and has the other end connected to the three-way valve, and a second portion that has one end disposed in the head cleaning container and the other end connected to the three-way valve. When the openable / closable flow path is closed, the first part communicates with the flow path for supplying the cleaning liquid to the ink supply port of the inkjet head via the three-way valve, and the inkjet head is connected to the inkjet head. When the cleaning liquid is supplied through at least two ink supply ports including the second ink supply port and the openable flow path is opened, the first portion and the ink jet are opened. A channel for supplying a cleaning liquid is shut off through the three-way valve in the ink supply port of the head, in which the part and the second part first has to be communicated via the three-way valve.
In the present invention, after the openable flow path of the second path is opened and the inkjet head is cleaned, the openable flow path of the second path is closed and the first path is The inkjet head is cleaned.
In the present invention, ultrasonic vibration is applied to the cleaning liquid in the head cleaning container, and the nozzles of the inkjet head immersed in the cleaning liquid in the head cleaning container are cleaned with the cleaning liquid that is ultrasonically vibrated.
According to the present invention, the frequency of the ultrasonic vibration is changed during the cleaning of the inkjet head.
According to the present invention, an actuator for a nozzle of the inkjet head is driven during cleaning of the inkjet head.

  According to the present invention, even if an inkjet head is packed with a large number of nozzles, the cleaning liquid can be transferred to the nozzle if the second path is first closed and the first path is cleaned after the second path is opened. Therefore, the ink jet head can be recovered step by step.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
The ultrasonic cleaning machine 2 includes a head cleaning container 6 that stores a cleaning liquid in which the inkjet head 4 is immersed, and includes an oscillator 8 and a vibrator 11 for applying ultrasonic vibration to the cleaning liquid. The oscillator 8 drives the vibrator 11 and applies ultrasonic vibrations to the cleaning liquid in the head cleaning container 6. As shown in FIG. 4, the oscillator 8 and a frequency for changing the oscillation frequency of the oscillator 10. A converter 12, an operation panel 14 for operating the frequency converter 12, an amplifier 16 that amplifies the output of the oscillator 10, and a power supply 18 that supplies a power supply voltage to the oscillator 10 and the amplifier 16. Composed.

  The frequency converter 12 is configured to be able to change the frequency of ultrasonic waves output from the oscillator 10 for ultrasonic cleaning to a plurality of frequencies set in advance from the operation panel 14. The frequency conversion unit 12 has a function of changing the output frequency of the transmission unit 10 stepwise and periodically. Here, stepwise means that, for example, the frequency is changed by 1 kHz, and when the set upper limit frequency is reached, it returns to the first frequency and repeats this. Periodic means that the frequency is changed at regular intervals. It is. The frequency may be set in several stages, for example, 28 kHz, 45 kHz, 100 kHz, etc., every tens of seconds, and the specifications may be arbitrarily selected.

  The head cleaning container 6 includes a support that detachably holds the inkjet head 4 at a cleaning position. The cleaning liquid tank 20 accommodates the cleaning liquid 22 therein, and one end of a tube 26 connected to the suction port of the pump 24 is disposed therein. The discharge port of the pump 24 is connected to the ink supply port 34 of the inkjet head 4 via a tube 30 to which the filter 28 is connected and a branch tube 32 communicating with the tube 30.

  The discharge port of the pump 24 is connected to the ink supply port 40 of the inkjet head 4 via the tube 30, the three-way valve 36, and the branch tube 38. The discharge port of the pump 24 communicates with the inside of the head cleaning container 6 through the tube 30, the three-way valve 36, and the branch tube 42. One end of the return tube 44 connected to the pump 46 and the filter 48 is disposed in the cleaning liquid tank 20, and the other end 44 a is disposed in the head cleaning container 6.

  The upper end position of the liquid surface of the cleaning liquid 22 inside the head cleaning container 6 is determined by the height of the other end 44 a of the tube 44. The filter 48 is connected to the suction port of the pump 46. A pipe 50, such as a pipe or a tube, is inserted into a hole formed in the upper part of the sealed cleaning liquid tank 20, and a ventilation hole 52 that communicates the inside of the cleaning liquid tank 20 with the outside air by the pipe 50. Is formed.

  The inkjet head 4 includes a large number of nozzles 54 that communicate with a common ink chamber 56. Each nozzle 54 is provided with an actuator for discharging ink from the nozzle. The ink jet head 4 uses a piezoelectric member as an actuator for discharging ink from the nozzle 54, or has a configuration in which ink is discharged from the nozzle 54 by boiling the ink using a heating element as an actuator. However, it becomes the object of cleaning by this apparatus.

  In this apparatus, the three-way valve 36 forms two circulation paths for the cleaning liquid. In the first path, the cleaning liquid in the cleaning liquid tank 20 is supplied into the common ink chamber 56 from the two ink supply ports 34 and 40 via the tube 26, and is discharged from the nozzle 54 into the head cleaning container 6. Return to the cleaning liquid tank 20 through 44. In the second path, the cleaning liquid in the cleaning liquid tank 20 is supplied to the common ink chamber 56 only from the ink supply port 34 on one side via the tube 26 and discharged into the head cleaning container 6 from the nozzle 54. The cleaning liquid filled in the ink chamber 56 flows back through the branch tube 38 and the branch tube 42 from the other ink supply port 40 and is discharged into the head cleaning container 6. The cleaning liquid in the head cleaning container 6 discharged from the nozzle 54 and the branch tube 42 returns to the cleaning liquid tank 20 through the tube 44.

Next, the operation of this apparatus will be described.
When the degree of clogging of the nozzles 54 of the inkjet head 4 to be cleaned is at a normal level, the first path is selected as the flow path to which the cleaning liquid is supplied. In this first path, the branch tube 42 is cut off from the tube 30 and the branch tube 38 by switching the direction switching valve of the three-way valve 36, and the tube 30 and the branch tube 38 are set to communicate with each other.

  In the head cleaning container 6, the inkjet head 4 supported by a support is disposed, and the nozzle 54 is immersed in the cleaning liquid 22 in the head cleaning container 6. On the other hand, a cleaning liquid 22 is stored in the cleaning liquid tank 20 in advance. When the pump 24 is driven, the cleaning liquid 22 in the cleaning liquid tank 20 is sucked up by the pump 24, and the cleaning liquid is injected from the two ink supply ports 34 and 40 of the inkjet head 4 through the filter 28.

  When the cleaning liquid is injected from the tube 30 into the common ink chamber 56 in the inkjet head 4, the cleaning liquid flows out from each nozzle 54. On the other hand, the oscillator 8 of the ultrasonic cleaning machine 2 is driven, the vibrator 11 vibrates, and the cleaning liquid in the head cleaning container 6 vibrates at a set frequency. The output frequency of the oscillator 10 of the ultrasonic cleaner oscillator 8 is changed stepwise and periodically under the control of the frequency converter 12. The cleaning liquid coming out of the nozzle 54 and entering the head cleaning container 6 raises the level of the cleaning liquid in the container 6.

  In this embodiment, the pump 46 is always driven. Therefore, when the liquid level in the head cleaning container 6 exceeds the other end 44 a of the tube 44, the cleaning liquid in the head cleaning container 6 is sucked up by the pump 46 and returned to the cleaning liquid tank 20 through the filter 48. As a result, the cleaning liquid circulates between the cleaning liquid tank 20 and the head cleaning container 6, and the liquid level in the head cleaning container 6 is maintained at a certain level.

  It should be noted that the liquid level of the head cleaning container 6 may be detected by a sensor, and the pump 46 may be driven only when the liquid level rises above a predetermined level to keep the liquid level at a certain level. The circulation of the cleaning liquid that sucks up the cleaning liquid from the cleaning liquid tank 20 and returns the cleaning liquid from the head cleaning container 6 to the cleaning liquid tank 20 is performed smoothly due to the presence of the vent holes 52. When the nozzles of the inkjet head 4 to be cleaned are clogged, the amount of outflow from the nozzles is small, and the common ink chamber 56 overflows with the cleaning liquid. Therefore, in this case, the second route is selected as shown in FIG.

  In this path 2, the branch tube 38 is disconnected from the tube 30 by switching the direction switching valve of the three-way valve 36, and the branch tube 38 and the branch tube 42 communicate with each other. Accordingly, when the cleaning liquid is sucked up from the cleaning liquid tank 20 by the pump 24 and injected into the common ink chamber 56 of the inkjet head 4 through the filter 28, this injection is only supplied from one ink supply port 34 by the branch tube 32. become.

  In the common ink chamber 56 of the inkjet head 4, the cleaning liquid is divided into an amount flowing out from the nozzle 54 and an amount in which the cleaning liquid overflowing from the common ink chamber 56 flows backward from the other ink supply ports 40 to the branch tube 42. The cleaning liquid that has flowed back to the branch tube 38 is discharged to the head cleaning container 6 through the three-way valve 36 and the branch tube 42. Other operations are the same as those of the first path shown in FIG. When clogging of the nozzle is improved during the cleaning of the inkjet head 4 and the overflow of the cleaning liquid in the common ink chamber 56 is eliminated, the three-way valve 36 is switched and returned to the first path. It should be noted that the pump 24 may be configured to change the flow rate and flow velocity so that various conditions can be met.

Next, another embodiment of the present invention will be described with reference to FIG.
The cleaning liquid tank 20 is hermetically sealed, and the upper part of the cleaning liquid tank 20 is connected to the air discharge port of the air pump 62 through a regulator 60 by a tube 58. The head cleaning container 6 is provided with a sensor 64 for detecting the liquid level. When the liquid level of the cleaning liquid in the head cleaning container 6 exceeds a predetermined level, the sensor 64 is activated and the pump 46 is used to operate the head cleaning container 6. The cleaning liquid 22 is sucked up and returned to the cleaning liquid tank 20 so that the liquid level in the head cleaning container 6 is always maintained at a predetermined level. Other configurations are the same as those of the embodiment shown in FIG.

  In the above-described configuration, when supplying the cleaning liquid to the common ink chamber 56 of the inkjet head 4 in the head cleaning container 6 via the tube 30, the direction switching valve of the three-way valve 36 is switched in advance to supply the cleaning liquid supply flow. The route is set to the first route or the second route. Next, the ultrasonic cleaner 2 is driven and the air pump 62 is driven. When the air pump 62 is driven, pressurized air is supplied from the tube 58 into the cleaning liquid tank 20, and the air pressure pressurizes the liquid level in the cleaning liquid tank 20, and the cleaning liquid in the cleaning liquid tank 20 is pushed up into the tube 26. Then, the ink is supplied to the common ink chamber 56 of the inkjet head 4 through the filter 24.

  Further, the dirty cleaning liquid in the head cleaning container 6 is filtered by the filter 48 and returned to the cleaning liquid tank 20, and the cleaning liquid circulates between the head cleaning container 6 and the cleaning liquid tank 20. During the cleaning of the inkjet head 4, the frequency of the ultrasonic vibration output from the ultrasonic cleaner 2 changes stepwise and periodically. In the above embodiment, the actuator of the inkjet head 4 may be driven during the cleaning of the inkjet head 4. Thereby, the foreign material adhering to the nozzle can be easily separated.

It is explanatory drawing of the inkjet head cleaning apparatus which concerns on this invention. It is explanatory drawing of the inkjet head cleaning apparatus which concerns on this invention. It is explanatory drawing of other embodiment of this invention. It is block explanatory drawing of the oscillator for ultrasonic cleaners.

Explanation of symbols

2 Ultrasonic Cleaning Machine 4 Inkjet Head 6 Head Cleaning Container 8 Oscillator 10 Oscillator 11 Oscillator 12 Frequency Converter 14 Operation Panel 16 Amplifier 18 Power Supply Unit 20 Cleaning Liquid Tank 22 Cleaning Liquid 24 Pump 26 Tube 28 Filter 30 Tube 32 Branching Tube 34 Ink supply port 36 Three-way valve 38 Branch tube 40 Ink supply port 42 Branch tube 44 Tube 46 Pump 48 Filter 50 Tube 54 Vent hole 56 Common ink chamber 58 Tube 60 Regulator 62 Air pump 64 Sensor

Claims (7)

The cleaning liquid in the cleaning liquid tank is injected by a pump into the ink jet head disposed in the head cleaning container, and the cleaning liquid discharged from the nozzle of the ink jet head is stored in a state where the nozzle of the ink jet head is immersed in the head cleaning container. An ink-jet head cleaning device provided with a flow path for returning the stored cleaning liquid to the cleaning liquid tank by a pump, and for the cleaning liquid entering from the ink supply port of the inkjet head to circulate through the cleaning liquid tank. A cleaning liquid is supplied from the inside to the at least one ink supply port of the inkjet head, and the cleaning liquid flows out from the nozzle of the inkjet head, and the cleaning liquid is supplied from the cleaning liquid tank to the at least one ink supply port of the inkjet head. Serving The cleaning liquid flows out from the nozzle of the ink jet head, and the cleaning liquid in the ink jet head is received from the other second ink supply port of the ink jet head, and the cleaning liquid in the ink jet head is led into the head cleaning container. A second path having a free flow path, and when there is little clogging of the nozzles of the inkjet head, cleaning is performed in the first path, and when a large number of nozzles of the inkjet head to be cleaned are clogged, An inkjet head cleaning apparatus, wherein cleaning is performed in the second path and the cleaning liquid supplied into the inkjet head is prevented from overflowing from a flow path upstream of the nozzle due to clogging of the nozzle. The inkjet head cleaning device according to claim 1, wherein a filtration device is provided in a flow path through which the cleaning liquid circulates. An openable and closable flow path for receiving the cleaning liquid in the ink jet head from the other second ink supply port of the ink jet head and guiding the cleaning liquid in the ink jet head into the head cleaning container has one end on the other side of the ink jet head. A first portion that is connected to the second ink supply port and has the other end connected to the three-way valve, and a second portion that has one end disposed in the head cleaning container and the other end connected to the three-way valve. When the openable / closable flow path is closed, the first portion communicates with the flow path for supplying the cleaning liquid to the ink supply port of the inkjet head via the three-way valve, and the second ink is connected to the inkjet head. When cleaning liquid is supplied through at least two ink supply ports including the supply port and the openable flow path is opened, the first portion and the ink jet head are connected to each other. The flow path for supplying the cleaning liquid to the supply port is blocked through the three-way valve, and the first part and the second part are communicated with each other through the three-way valve. 2. An inkjet head cleaning apparatus according to 1. After the openable flow path of the second path is opened and the inkjet head is cleaned, the openable flow path of the second path is closed and the inkjet head is cleaned by the first path. The inkjet head cleaning apparatus according to claim 1, wherein the inkjet head cleaning apparatus is performed. 2. The ultrasonic vibration is applied to the cleaning liquid in the head cleaning container, and the nozzles of the inkjet head immersed in the cleaning liquid in the head cleaning container are cleaned with the cleaning liquid that is ultrasonically oscillated. Inkjet head cleaning device. 6. The inkjet head cleaning apparatus according to claim 5, wherein a frequency of the ultrasonic vibration is changed during cleaning of the inkjet head. 6. The ink jet head cleaning apparatus according to claim 1, wherein an actuator for a nozzle of the ink jet head is driven during cleaning of the ink jet head.

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