JP2009269291A - Inkjet apparatus - Google Patents

Abstract

【Task】
Provided is an ink jet apparatus capable of performing stable liquid application by performing maintenance so that a recording head is in an optimum state using a minimum time and a cleaning liquid.
[Solution]
Select a maintenance unit that has a means to detect the degree of sedimentation or accumulation of fine particles in the ink chamber and a means to detect the number of ink ejection defects or ejection bends, and to recover the recording head according to the results. In this way, minimize the time required for recovery and the amount of cleaning solution used.
[Selection] Figure 1

Description

  The present invention comprises an inkjet recording head that discharges a liquid (ink) mixed with a solvent and fine particles as droplets and its control means, and a stage that controls the relative position between the substrate to be coated and the inkjet recording head. The present invention relates to an ink jet apparatus for the purpose of applying ink to the top. In particular, the present invention relates to a control device and a control method for maintaining the stability of droplet discharge from an ink jet recording head.

Conventionally, ink jet devices have been used as output means of information processing systems.
This ink jet apparatus records characters, figures, etc. by ejecting minute droplets from nozzles, and has a feature that a high-definition image can be recorded. By using multi-colored ink, it is possible to print a color image, and it is easy to reduce the size of the device and increase the resolution of the image. It is circulating. Recently, the number of industrial inkjet devices for printing metal wiring on various substrates and printing color filters for displays is also increasing.

  In such an industrial inkjet apparatus, an ink bottle is connected above the inkjet recording head so that ink can be supplied to the minute ink chambers arranged in the recording head with an appropriate pressure. Appropriate pressure means that the pressure in the ink chamber is a negative pressure of several hundred Pa with respect to the atmospheric pressure, and an instantaneous large pressure is applied to the ink in the ink chamber in this state. Ink is ejected toward the recording medium from minute holes (orifices) formed in the wall surface.

  As a method of applying an appropriate pressure to the ink chamber, as disclosed in Japanese Patent Application Laid-Open No. 2004-121942, a method of adjusting the amount of negative pressure by providing a negative pressure generating means in an ink bottle connected to a recording head. Is disclosed.

  In the state where ink is supplied to the ink chamber at an appropriate pressure by the above method or the like, the ink is always in contact with the atmosphere. Therefore, if the state where ink is not ejected becomes longer, the ink solvent near the orifice volatilizes and the ink is discharged. As the viscosity increases, the printing speed decreases, and the print direction deteriorates because the discharge direction is bent.

  In order to prevent deterioration in print image quality, the ink is periodically ejected to a position other than the recording medium to suppress the increase in viscosity. There is a method of sucking out the ink having increased from the orifice.

  In addition, when fine particles are mixed in the ink, a clogging in the recording head causes a phenomenon that ink ejection stops and print image quality deteriorates. Specifically, clogging is because the microparticles in the ink are slightly larger than the specific gravity of the ink solvent, so that the microparticles settle in the ink chamber over time, or the ink flow velocity such as the bent portion of the ink flow path. A phenomenon in which fine particles accumulate in a small area occurs, and the ink flow decreases. As sedimentation and accumulation of fine particles proceed, ink discharge from the orifice eventually stops.

  Another cause of image degradation is dirt around the orifice during printing. In this mechanism, when ink is ejected while the recording head moves on the recording medium, ink that bounces off the recording medium adheres to the periphery of the orifice of the recording head. That is, the ink ejection direction is bent and the image quality deteriorates.

  As a method for preventing the above problem, as described in Japanese Patent Application Laid-Open No. 2004-106304, in addition to abutting the cap against the recording head and making the inside of the cap negative pressure, the ink is sucked out from the orifice, and printing is performed. There is a method of recovering clogging by applying a voltage higher than the driving voltage at the time and ejecting ink with a strong pressure.

  Japanese Patent Application Laid-Open No. 2004-121942 describes a method of recovering clogging by forcibly ejecting ink (or flushing) from an orifice by pressurization during non-printing.

  As a method for recovering clogging of the recording head, as described in JP-A-2004-358667, the inside of the ink flow path is cleaned by immersing the recording head in a cleaning liquid and applying ultrasonic vibration. There is a way to do it.

  Japanese Patent Application Laid-Open No. 2004-209460 describes that maintenance is performed when an abnormality is detected by observing the ink discharge state.

JP 2004-121942 A JP 2004-106304 A JP 2004-358667 A JP 2004-209460 A

  Due to the high-definition printing performance of inkjet devices, not only personal recording devices but recently various types such as industrial inkjet devices that print metal wiring on various substrates and color filters for displays. Inkjet devices are on the market. Most of the inks used in these ink jet devices are those in which a dye containing no particles is dissolved in a liquid and those in which a pigment having a diameter of about 0.1 to 0.5 μm is dispersed. .

  However, even with ink in which particles having a diameter of up to about 1/10 are distributed to an orifice with a diameter of 30 to 50 μm, it can be applied in a short period of time. In order to secure the liquid crystal layer, it is possible to apply spacer particles applied on the glass substrate. In order to enable long-term application, the particles in the ink tend to settle with time, so that the solvent has a higher viscosity than the dye ink or the ink in which the pigment having a diameter of about 0.1 to 0.5 μm is dispersed. It is necessary to devise the ink itself, for example, to be dispersed. Examples of the high-viscosity solvent for dispersing the particles include a diol solvent and water mixture. However, even when dispersed in a high-viscosity solvent, sedimentation of particles in the ink occurs in a time of several ten minutes to several hours. In the ink jet apparatus using the ink in which the particles are dispersed, the following two problems occur.

  The first problem is that the fine particles in the ink are slightly larger than the specific gravity of the ink solvent, so that the fine particles settle in the ink chamber over time, or the ink flow velocity at the bent portion of the ink flow path is small. A phenomenon in which fine particles accumulate at the place occurs, and the flow of ink decreases. Then, sedimentation and accumulation of fine particles proceed, and ink discharge from the orifice is eventually stopped.

  The second problem is that, when the recording head is ejecting ink while moving on the recording medium, the ink splashed from the recording medium adheres to the periphery of the orifice of the recording head. When ink adheres to the periphery of the orifice, the ink is ejected so as to be attracted to the ink, so that the ink ejection direction is bent and the image quality is deteriorated. When using dye ink or ink in which a pigment having a fine particle size is dispersed, the ink near the orifice can be wiped off. However, if the ink in which particles of several μm are dispersed is repeatedly wiped off, the orifice will eventually be removed. This means that the life of the recording head is shortened. As a method for preventing the above problem, as described in Japanese Patent Application Laid-Open No. 2004-106304, in addition to abutting the cap against the recording head and making the inside of the cap negative pressure, the ink is sucked out from the orifice, and printing is performed. Although there is a method of recovering clogging by applying a voltage higher than the driving voltage at the time and ejecting ink with a strong pressure, it is difficult to recover sedimentation and deposition of fine particles.

  Further, as described in Japanese Patent Application Laid-Open No. 2004-358667, there is a method of cleaning the inside of the ink flow path by immersing the recording head in a cleaning liquid and applying ultrasonic vibration. A sufficient consideration has not been given to the method of reducing the amount of cleaning liquid to be used and the method of reducing the apparatus stop time, which should be taken into account when mounted on the recording apparatus.

  In addition, as described in Japanese Patent Application Laid-Open No. 2004-209460, there is a method of performing maintenance by observing the discharge state. However, the above publication also gives sufficient consideration to a method of reducing the amount of cleaning liquid and the apparatus stop time. Absent.

In order to solve the above two problems, a maintenance process for keeping the recording head in an optimum state is necessary. In the maintenance process of the recording head, there is a difference between the process time and the amount of liquid used for cleaning depending on the content. It is important to shorten the time during which the ink jet apparatus is stopped as much as possible and to reduce the amount of liquid used for cleaning as much as possible.
For example, if you have a serious hindrance to ink ejection, start with a maintenance method that recovers minor abnormalities, and if it still does not recover, proceed to a method that recovers more severe abnormalities. The time for performing a maintenance method for recovering a minor abnormality and the liquid required for cleaning are wasted. In addition, if a method is used in which the frequency of executing each maintenance method is determined in advance, a maintenance method for severe abnormalities that originally requires a lot of time and liquid for cleaning is not required. Even so, if the maintenance method is executed, time and cleaning liquid are wasted.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet apparatus that efficiently applies an ink containing particles of several μm onto a recording medium, and has a method for efficiently maintaining a recording head in an optimum state, and enables stable liquid application. Is to provide. Specifically, it has means for detecting the ink flow rate in order to know the degree of sedimentation and accumulation of fine particles in the ink chamber, and means for detecting the number of ink discharge defects and the discharge state of the discharge curve. Accordingly, it is an object of the present invention to provide a highly efficient ink jet apparatus capable of minimizing the time required for recovery and the amount of cleaning liquid used by selecting maintenance means for recovering the recording head.

  In order to achieve the above object, the inkjet apparatus has the following configuration.

  In addition to the ink in which the particles are dispersed, a liquid bottle containing the solvent of the ink not containing particles and a cleaning agent having a viscosity lower than that of the ink is arranged, and the liquid is discharged from all the liquid bottles into the recording head. A pressurizing unit that pressurizes and inflows; and a switching unit that switches inflow of the ink and the cleaning liquid into the recording head. There are two bottles that contain ink in which particles are dispersed, a flow path is formed from the first bottle to the second bottle via the recording head, and the pressure gradient from the first bottle to the second bottle And a means for detecting the flow rate of ink flowing between them. In addition, there is a means for detecting the ejection state by ejecting ink at a position away from the coating position when the recording head is not coated. In addition, as a recording head maintenance means, a cap that contacts the recording head and covers the orifice array, and when the liquid that has flowed into the recording head by the pressurizing means leaks from the orifice to the cap, a negative is put into the cap. In a state where the pressure is generated to suck the liquid, the cleaning liquid is sent into the cap, the liquid feeding means for washing the liquid around the orifice with the cleaning liquid, and the cleaning liquid sent by the liquid feeding means is stored in the cap. A liquid feeding means is provided for sucking the cleaning liquid from the orifice into the recording head and sending the cleaning liquid to a separate recovery bottle. And it has a means to control to execute any one of the recording head maintenance means based on the detection results of the ink flow rate detection means and the means for detecting the discharge state.

  According to the present invention, there are provided means for detecting the degree of sedimentation and accumulation of fine particles in the ink chamber, and means for detecting the number of ink ejection defects and the ejection state of the ejection curve. By selecting the means for recovery, the time required for recovery and the amount of cleaning liquid used can be minimized.

Example 1
Hereinafter, embodiments of the invention will be described with reference to the drawings.

  FIG. 4 is a side view of a configuration example of the ink jet apparatus according to the embodiment of the present invention, and FIG. 5 is a front view of the configuration example of the ink jet apparatus.

  This inkjet apparatus is an apparatus that prints a desired dot pattern on a substrate 103 that is adsorbed by an x-direction moving mechanism 102 in a stage 101. The dot pattern is formed of ink containing particles having a diameter of 2 to 5 μm.

The recording head 1 fixed to the y-direction moving mechanism 104 is connected to the first ink bottle 4 and the second ink bottle 5, and the recording head 1 faces the substrate 103 in accordance with a signal from an ink application controller (not shown). Ink is ejected from orifices arranged at equal intervals on the surface.
When the substrate 103 adsorbed by the x-direction moving mechanism 102 is transported in the + x direction in accordance with the ink ejection from the recording head 1, a band-shaped ink dot pattern having a constant width is formed on the substrate 103. When one transport by the x-direction moving mechanism 102 is completed, the recording head 1 is moved by a certain distance by the y-direction moving mechanism 104, and the substrate 103 adsorbed by the x-direction moving mechanism 102 is transported again in the -x direction. As a result, the next ink dot pattern is formed on the substrate 103.

  Further, the displacement amounts of the x-direction moving mechanism 102 and the y-direction moving mechanism 104 are detected by a detecting means such as an encoder (not shown) existing inside the stage, and are taken into a controller or the like.

  In this ink jet apparatus, there are a plurality of ink bottles 2, 3, 6, 7 different from the first ink bottle 4, and a cap 8 arranged so as to cover the orifice surface of the recording head 1. An ink supply system that supplies ink from the bottle to the recording head 1 and a recording head maintenance system that cleans the recording head 1 and the like exist so that the ink ejection from the recording head 1 is optimal. . There is also a photographing device 61 that photographs the ink ejection state. These mechanisms will be described below with reference to another drawing. Further, in this embodiment, one example of the recording head 1 is described, and the maintenance system is described so as to correspond to one recording head. However, an actual inkjet apparatus includes a plurality of recording heads 1. There is also a maintenance system for each recording head.

  FIG. 6 is a diagram showing an ink supply system and a recording head maintenance system of the ink jet apparatus according to the present invention. In this example, six bottles are arranged inside the ink jet apparatus. 2 is a cleaning agent bottle, 3 is an ink solvent bottle, 4 is a first ink bottle, 5 is a second ink bottle, 6 is a first recovery bottle, and 7 is a second recovery bottle. In the first ink bottle 4 and the second ink bottle 5, stir bars 41 and 51 each containing a magnetic material are arranged, and the stir bars 41 and 51 are rotated by stirrers 42 and 52 in which magnets rotate. Then stir the ink.

Pipes extend from each bottle, and the liquid inside the bottle is moved by the air pumps 11 to 16, the water pumps 17 and 18, and the three-way valves 21 to 25, and ink supply and maintenance to the recording head 1 are performed. The recording head 1 is provided with a plurality of ink inlets.
Hereinafter, an ink supply method and a recording head maintenance method will be described sequentially.

  First, an ink supply method will be described with reference to FIG. FIG. 7 is a redrawing of the piping diagram of FIG. 6 with emphasis on the piping related to the ink supply.

  Before performing ink application with the recording head 1, first, the cleaning agent contained in the cleaning agent bottle 2 is introduced into the recording head 1. The cleaning agent has a low viscosity and surface tension, and is a liquid that does not react with the solvent of the ink in which the particles are dispersed, and alcohol or the like is suitable. The role of the cleaning agent is to remove bubbles present in the recording head 1. The three-way valves 21, 22 and 23 are operated so that the cleaning agent enters the recording head 1, and the cleaning agent bottle 2 is pressurized with the air pump 11 to push the cleaning agent into the recording head 1. At this time, the three-way valve 24 is operated so that the cleaning agent flows into the first recovery bottle 6 to remove bubbles from the recording head 1. Since the cleaning agent is also ejected from the orifice of the recording head 1, the cleaning agent is received by the cap 8 and sucked into the second recovery bottle 7 by the air pump 15.

  Next, the ink solvent accommodated in the ink solvent bottle 3 is introduced into the recording head 1. The reason why only the ink solvent is introduced before introducing the ink in which the particles are dispersed is that if the cleaning agent having a low viscosity and the ink are mixed suddenly, the particles are likely to settle, and aggregation of the particles occurs inside the recording head 1. This is to prevent the occurrence of this aggregation. The three-way valves 21, 22, and 23 are operated so that the ink solvent enters the recording head 1, and the ink solvent bottle 3 is pressurized by the air pump 12 to push the ink solvent into the recording head 1. At this time, the cleaning agent is removed from the recording head 1 so that the ink solvent flows into the first recovery bottle 6 without changing the state of the three-way valve 24. Since the ink solvent is also ejected from the orifice of the recording head 1, the ink solvent is received by the cap 8 and sucked into the second recovery bottle 7 by the air pump 15.

  Finally, the ink stored in the first ink bottle 4 is introduced into the recording head 1. Similarly to the introduction of the two kinds of liquids, the three-way valve 23 is operated to pressurize the inside of the first ink bottle 4 with the air pump 13 and push the ink into the recording head 1. At this time, without changing the state of the three-way valve 24, the ink solvent flows into the first recovery bottle 6 so that the recording head 1 is filled with ink in which particles are dispersed. Since ink is also ejected from the orifice of the recording head 1, the ink is received by the cap 8 and sucked into the second recovery bottle 7 by the air pump 15. In addition, when the inside of the pipe between the recording head 1 and the three-way valve 24 is completely replaced with ink, the ink may be introduced into the second ink bottle 5 by operating the three-way valve 24. The ink in the second ink bottle 5 is periodically returned to the first ink bottle 4 and reused. At that time, the filter 9 provided for removing foreign matter contained in the ink is passed.

  In this state, since ink droplets are attached to the orifice surface of the recording head 1, the cap 8 is brought into close contact with the recording head 1 and the ink is sucked into the second recovery bottle 7 by the air pump 15.

  Through the above steps, ink can be introduced into the recording head 1. Thereafter, the ink discharge state from all the orifices is confirmed.

  FIG. 17 is a diagram illustrating a method of confirming the ink discharge state from all the orifices. An imaging device 61 that captures the ink ejection state includes a light source 401 that blinks in synchronization with a drive signal that ejects ink from the recording head 1, a camera 402 that displays ejected liquid droplets, and an image that is projected by the camera 402. It is comprised from the apparatus which displays. The camera 402 photographs the ink droplet row 403 ejected from the recording head 1 while moving. Since the light source 401 blinks in synchronization with the drive signal, the stationary ink droplet row 403 is photographed. At that time, it is possible to observe a defect state where ink is not ejected and a bending in the ejection direction. If ink ejection from all the orifices cannot be observed, ink pressure introduction and ink suction with the cap 8 in close contact with the recording head 1 are executed once again. Still, when ink ejection from all the orifices cannot be observed, it relates to the problem solving method of this embodiment, and will be described in detail later.

  Next, a method for supplying ink to the recording head 1 in a normal ink application state will be described with reference to FIG. FIG. 8 is a redrawing of the piping diagram of FIG. 6 with emphasis on the piping related to the ink supply.

  When ink application is started by the recording head 1, the pressure inside the recording head 1 is generally set to a negative pressure of several hundred Pa (several tens of mmaq) that prevents ink from dripping from the orifice of the recording head 1. Is. Therefore, the three-way valve 23 is operated to connect the first ink bottle 4 and the recording head 1, and the inside of the first ink bottle 4 positioned above the recording head 1 is decompressed by the air pump 13, Is set to a predetermined pressure. An example of the state of the water head pressure (an example of pressure setting performed in the experiment) is shown in FIG. In this example, when the height difference between the recording head 1 and the first ink bottle 4 is h (mm), the reduced pressure is set to h + 50 (mm). Since the recording head 1 and the second ink bottle are not connected by the three-way valve 24 and there is no ink flow, the water head pressure of the first ink bottle 4 and the recording head 1 is the same. Thereafter, as described with reference to FIG. 4, ink is ejected from the orifices arranged at equal intervals toward the substrate 103 in accordance with the signal of the ink application controller. A belt-like ink dot pattern having a constant width is formed on the substrate 103 by transporting the substrate 103 adsorbed by the x-direction moving mechanism 102 in accordance with ink ejection from the recording head 1. While such an operation is repeated, sedimentation of particles in the ink starts in the recording head 1. When the sedimentation of the particles occurs, the number of particles contained in one drop greatly changes or the orifice is clogged. For this reason, it is necessary to prevent clogging of the recording head 1 and to stably apply ink, and several maintenance means for the recording head 1 are mounted. The maintenance means will be described in detail later.

  Next, the end operation of the ink jet apparatus will be described.

  When the ink jet apparatus is terminated, the liquid is introduced into the recording head 1 in the reverse order of the ink supply method in order to prevent sedimentation of particles in the ink. That is, the ink solvent containing no particles is introduced under pressure, and then the washing liquid is introduced under pressure, and the operation of the ink jet apparatus is terminated in a state where the cleaning agent is introduced into the recording head 1.

In the foregoing, a series of operations from the ink supply method at the start-up of the ink jet apparatus to the end operation has been described. Hereinafter, a maintenance method (cleaning method) of the recording head, which is important for continuously performing ink application more stably than the ink jet apparatus, will be described.
Hereinafter, several existing recording head maintenance methods will be described in order.

  First, a method (suction mode) for removing thickened ink and fixed matter near the orifice by suction on the nozzle surface of the recording head will be described.

  While the operation of forming the ink dot pattern on the substrate 103 is repeated according to the signal from the ink application controller, the particles in the ink begin to settle in the recording head 1. When ink application to the entire surface of one substrate 103 is completed, there is a waiting time until the next substrate 103 is transported. In order to prevent sedimentation of particles in the recording head 1 within the waiting time, the recording head 1 is moved to a position where the cap 8 exists, and then the recording head 1 is pressed against the cap 8 so that ink is discharged from the orifice. Suction. Specifically, as shown in FIG. 8, the cap 8 is pressed against the recording head 1, the three-way valve 25 is operated to connect the cap 8 and the second recovery bottle 7, and negative pressure is applied by the air pump 15. And the ink is sucked into the second recovery bottle 7.

  Next, a method (pressure mode) for forcibly ejecting ink by pressurizing ink onto the recording head 1 and removing the ink and fixed matter thickened near the orifice will be described.

  This mode is also performed after moving the recording head 1 to a position where the cap 8 exists. In this mode, similarly to the ink filling method described with reference to FIG. 7, the three-way valve 23 is operated to pressurize the inside of the first ink bottle 4 with the air pump 13 and push the ink into the recording head 1. At this time, the state of the three-way valve 24 is such that no ink flows from the recording head 1 so that the ink in the first ink bottle 4 is ejected from the orifice. In order to receive the ink ejected from the orifice, the recording head 1 is brought close to or in contact with the cap 8, and then the three-way valve 25 is operated to connect the cap 8 and the second recovery bottle 7. A negative pressure is generated to suck the ink into the second collection bottle 7.

  Next, the surface cleaning mode for cleaning the orifice surface of the recording head 1 will be described.

  The reason why the cleaning mode is necessary is that if the recording head 1 moves on the recording medium while ejecting ink, the ink splashed from the recording medium adheres to the periphery of the orifice of the recording head 1 and is ejected. This is because the ink direction is bent.

  The operation in the surface cleaning mode will be described with reference to FIG. FIG. 9 shows the piping of the portion related to the cleaning of the orifice surface in the piping diagram of FIG.

  Cleaning of the orifice surface of the recording head 1 uses a cleaning agent accommodated in the cleaning agent bottle 2. The three-way valves 21 and 22 are operated so that the cleaning agent enters the cap 8, and the cleaning agent bottle 2 is pressurized by the air pump 11 to introduce the cleaning agent into the cap 8. The recording head 1 is brought close to the cap 8 to clean the orifice surface with the cleaning liquid. The surface cleaning method will be described with reference to FIGS.

  FIG. 11 shows the structure of the cap 8. The cap 8 includes an inner container 8a and an outer container 8b. The pipe 201 is a pipe for introducing the cleaning agent into the inner container 8a, the pipe 202 is a pipe for discharging the cleaning agent overflowed from the inner container 8a, and the pipe 203 is a pipe for discharging the ink in the inner container. .

  FIG. 12 shows a method for cleaning the orifice surface of the recording head 1. In order to clean the orifice surface, first, the recording head 1 is brought close to the inner container 8a of the cap 8, and the pipe 201 is used to flow the cleaning agent into the inner container 8a. The cleaning agent 204 of the inner container 8a or more volume overflows into the outer container 8b while cleaning the orifice surface of the recording head 1. Particles adhering to the orifice surface are removed by the flow of the cleaning agent 204. The cleaning agent in the ink outer container 8 b is sucked by the air pump 15 and moves to the second recovery bottle 7 through the pipe 202. After the cleaning of the orifice surface is completed, the cleaning liquid in the inner container 8 a moves to the second recovery bottle 7 through the pipe 203.

  By performing the above-described cleaning, the orifice surface can be cleaned without rubbing, so that the orifice surface is not damaged by particles in the ink. Therefore, it can be used without shortening the life of the recording head 1.

  After cleaning the orifice surface, since the cleaning agent has entered the recording head 1 through the orifice, a step of introducing ink in which particles are dispersed into the recording head 1 is performed. Next, a mode in which the cleaning agent is sucked into the recording head 1 from the orifice side and aggregates are discharged from the discharge flow path of the recording head 1 will be described. In order to effectively discharge the aggregates, the recording head 1 is immersed in a cleaning liquid, and after applying ultrasonic vibration, the aggregates are crushed and dispersed, and the aggregates are discharged. Call.

  The case where the ultrasonic cleaning mode is required is a case where particles are aggregated in the recording head and ink ejection becomes unstable. The operation in the ultrasonic cleaning mode will be described with reference to FIGS.

  FIG. 10 is a diagram in which the portion of the piping related to this mode is rewritten thickly in the piping diagram of FIG. In order to discharge the aggregates inside the recording head 1, a cleaning agent contained in the cleaning agent bottle 2 is used. In order to discharge the aggregates inside the recording head 1, a cleaning agent contained in the cleaning agent bottle 2 is used.

  The step of discharging aggregates from the discharge flow path of the recording head 1 starts by replacing the ink in the recording head 1 with an ink solvent. This is because when ink having a high viscosity and a cleaning agent having a low viscosity are mixed, aggregation of particles in the ink occurs. The three-way valves 21, 22, and 23 are operated so that the ink solvent enters the recording head 1, and the ink solvent bottle 3 is pressurized by the air pump 12 to push the ink solvent into the recording head 1. Since the ink solvent is also ejected from the orifice of the recording head 1, the ink solvent is received by the cap 8 and sucked into the second recovery bottle 7 by the air pump 15. Thereafter, the three-way valve 21 is operated to pressurize the cleaning agent bottle 2 with the air pump 11 and push the cleaning agent into the recording head 1. Thereafter, the recording head 1 is moved from a position facing the cap 8 to a position facing the ultrasonic cleaning tank 300.

  FIG. 15 shows the state of the piping when performing ultrasonic cleaning. The three-way valve 26 is a valve for switching between the cap 8 and the ultrasonic cleaning tank. The cleaning liquid after cleaning is recovered in the second recovery bottle 7 through the valve 310. A detailed cleaning method will be described with reference to FIG.

  The ultrasonic cleaning tank 300 includes an outer tank 301 that stores water and an inner tank 302 that stores a cleaning liquid. The outer tank 301 is configured such that water enters from the pipe 303 and exits from the pipe 304. The inner tank 302 is configured such that the cleaning liquid enters from the pipe 305 and exits from the pipe 306. By contacting the orifice surface of the recording head 1 with the inner tank 302 and vibrating the ultrasonic vibrator disposed at the lower part of the outer tank, the fixed matter inside the recording head 1 is crushed and dispersed in the cleaning liquid. The Thereafter, the cleaning agent is sucked into the recording head 1 from the orifice side, and the aggregate is discharged from the discharge flow path of the recording head 1. This process is shown below.

  First, the recording head 1 is brought into contact with the cleaning liquid in the inner tank 302 and the orifice surface. While continuing to supply the cleaning agent to the inner tank 302, the three-way valve 24 is operated so that the recording head 1 and the first recovery bottle 6 are connected, and the inside of the first recovery bottle 6 is made negative by the air pump 14, The cleaning agent in the cap 8 is sucked into the first recovery bottle 6. At this time, the three-way valve 23 is operated so that the recording head 1 and other bottles are not connected. The fixed matter existing in the recording head 1 is dispersed in the cleaning agent and discharged to the outside.

  After executing the ultrasonic cleaning mode, as described in the description of the ink introduction, the step of introducing the liquid into the recording head 1 in the order of the cleaning liquid, the ink solvent not containing particles, and the ink containing particles is executed, Prepare to start ink application.

  As described above, the ink application from the recording head 1 can be stabilized by performing the maintenance of the various recording heads described above. The maintenance is performed after the substrate or recording head has been scanned once and after the ink has been applied to the entire substrate, but the latter is the time until the next substrate is transported. Since there is time, it is common to perform maintenance at this timing. When the execution cycle of each maintenance method is determined in advance, the following problems occur. This is because when the recording head 1 has been used for a long time and deteriorated, a maintenance method that requires only a short time cannot perform sufficient cleaning, and the maintenance method is repeated many times. Furthermore, there may be a case where a troublesome maintenance method is subsequently performed. In that case, the total time required for the maintenance becomes longer, and the amount of liquid (cleaning liquid, ink solvent, ink) used for the maintenance also increases. It is to end. The deterioration state of the recording head 1 varies depending on the viscosity of the ink to be used, the diameter of the particles, the concentration of the particles, the number of ink applied per unit time, and the like, and there is a large variation among the recording heads 1. In order to minimize the amount of liquid used for cleaning and the cleaning time that is required for maintenance, the state of the recording head 1 (the degree of clogging of the ink flow path, the number of orifices with abnormal ink ejection, etc.) is detected. Thus, it is effective to select an optimum maintenance method based on the result. Hereinafter, this method will be described in detail.

  First, a method for measuring the degree of clogging of the ink flow path will be described with reference to FIG.

  The degree of clogging is measured in order to prevent ink settling in the recording head 1 due to continued ink application, and after the ink application to the entire substrate is completed, the next substrate is transported. The process is performed by using a process in which the ink is allowed to flow in the recording head 1 at a flow rate of a certain value or more before it comes. The degree of clogging can be measured by measuring the amount of ink that has flowed in a predetermined time while keeping the pressure difference between the ink supply source and the recovery destination constant. Specifically, the air pumps 13 and 16 are used to adjust the pressure in the first ink bottle 4 and the pressure in the second ink bottle 5 to the pressure shown in FIG. It operates so that the 2nd ink bottle 5 may be connected. This pressure setting is such that the water head pressure in the recording head 1 is equivalent to that during ink application based on the example of FIG. 13 which is the pressure setting value for normal ink application. Since the water head pressure in the recording head 1 is set to a pressure at which ink does not leak from the orifice, the flow meter immediately before the output of the liquid level sensor 31 provided in the first ink bottle or the ink introduction part to the recording head 1. By providing 32, the flow rate of the flow path inside the recording head can be measured. Note that the set values in FIG. 14 are examples, and other set values may be used as long as ink does not leak from the orifices of the recording head 1. The flow rate at the pressure set value in FIG. 14 is measured, and the result indicates the degree of clogging (abnormality) of the flow path. The relationship between the flow rate and the degree of abnormality in the recording head 1 and ink (viscosity 11 mPa · s) used in the experiment is as shown in FIG.

  After the flow rate measurement, the ink in the second ink bottle 5 is periodically returned to the first ink bottle 4 by the water pump 17. At that time, the filter 9 for removing foreign matter contained in the ink is passed.

  Next, determination of the degree of abnormality of the ink ejection state will be described. The determination of the degree of ink discharge abnormality is performed by the ink discharge observation described above with reference to FIG. The number of defects and the number of ejection bends are observed by ink ejection observation, and the degree of abnormality is determined based on the reference shown in FIG.

  The optimum maintenance method is selected based on the determination result of the degree of clogging (abnormality) of the ink flow path and the degree of abnormality of the ink ejection state described above. In other words, a method is selected in which the lighter the degree of abnormality, the shorter the maintenance time with less liquid (cleaning liquid, ink solvent, ink).

  FIG. 1 shows a method of selecting an optimal maintenance method based on the determination result of the degree of clogging (abnormality) of the ink flow path and the abnormality degree of the ink ejection state. As the degree of abnormality of the determination result increases, the cleaning time and the amount of liquid (cleaning liquid, ink solvent, ink) required for cleaning increase. Specifically, when the two determination results are normal, the maintenance operation is not performed. When the degree of clogging of the ink flow path is normal and the ink discharge state is lightly abnormal, start from the suction mode. When the degree of clogging of the ink flow path is slightly abnormal, the pressure mode is started. When at least one determination result is moderately abnormal, the surface cleaning mode is started, and when at least one determination result is severely abnormal, the ultrasonic cleaning mode is started. If the ink ejection is not recovered even after executing each maintenance method, the same mode is repeated or the upper maintenance method is shifted to. The flowchart of this execution method is shown in FIGS.

  FIG. 2 is a flowchart when starting from the suction mode. After the suction mode is executed, a discharge inspection is performed. If the discharge state from all orifices is normal, the maintenance contents (date and time, number of executions, etc.) are stored in the maintenance execution recording memory (not shown) ) And then ink application on the substrate is started. When the ejection state is not normal, the suction mode is performed once again, and when the ejection inspection is performed and becomes normal, the contents of maintenance are recorded in the memory as described above, and ink application is started. Here, when the discharge state is not normal, the surface cleaning mode is entered. When the surface cleaning mode is completed, a discharge inspection is performed. When the discharge state from all the orifices becomes normal, the contents of maintenance are recorded in the memory and ink application is started. If the discharge state is not normal, the surface cleaning mode is performed once again. When the discharge state from all the orifices becomes normal, the content of maintenance is recorded in the memory and ink application is started. If the discharge state is still not normal, the process proceeds to the next ultrasonic cleaning mode. This mode is repeated up to four times, and if it still does not become normal, the recording head is replaced, the operation of the apparatus is stopped, and a head replacement message is displayed on the display unit installed in the ink jet apparatus.

  Even if the ultrasonic mode is not executed four times in a row, if the ultrasonic mode is executed frequently (for example, twice or more per day), the life of the recording head is near, so prepare for head replacement. Display a prompting message on the display. This is because when the discharge state from all orifices becomes normal, the contents of maintenance (date and time, number of executions, etc.) are recorded in the maintenance execution recording memory, so a message can be displayed on the display unit. Is possible. It is also possible for the operator of the ink jet apparatus to determine the life of the recording head by referring to the maintenance execution recording. Note that although the reference for the recording head replacement is the ultrasonic cleaning mode 4 times, this is one guideline and may be 3 times or 5 times.

  FIG. 3 is a flowchart when starting from the pressurizing mode. After the pressurization mode is executed, a discharge inspection is performed. If the discharge state from all orifices becomes normal, the maintenance details are recorded in the memory for maintenance execution in the ink jet device, and the ink on the substrate is recorded. Start application. When the discharge state is not normal, the pressurization mode is performed once again, and when the discharge inspection is performed and becomes normal, the contents of maintenance are recorded in the memory as described above, and the application is started. Here, when the discharge state is not normal, the surface cleaning mode is entered. The contents are the same as those described with reference to FIG.

  By performing the ink introduction method and the recording head maintenance method described above, it is possible to realize an ink jet apparatus capable of stable liquid application.

(Example 2)
In the description of the first embodiment, alcohol is used as the cleaning agent. However, in order to enhance cleaning in the recording head 1, a bottle having a liquid in which a surfactant is dissolved in water may be provided separately.

  A liquid in which a surfactant is dissolved in water (hereinafter referred to as “surfactant water”) is mainly used for cleaning in the recording head 1, so the recording head is sucked into the recording head from the orifice side. Used when discharging aggregates from 1.

  First, the recording head 1 is brought close to the inner container 8a of the cap 8, and the surfactant water is poured into the inner container 8a. The surfactant water of the inner container 8a or more volume overflows into the outer container 8b while washing the orifice surface of the recording head 1. Particles adhering to the orifice surface are removed by the flow of the surfactant water. The surfactant water in the ink outer container 8 b is sucked by the air pump 15 and moves to the second recovery bottle 7 through the pipe 202. After the cleaning is completed, the surfactant water in the inner container 8 a moves to the second recovery bottle 7 through the pipe 203.

  After this cleaning, as in the first embodiment, a step of introducing the ink contained in the first ink bottle 4 into the recording head 1 is performed so that the ink can be applied.

(Example 3)
In the description of the first embodiment, an example in which a cleaning agent is used for ink introduction before and after ink application has been described. When the viscosity of the ink solvent for ink application is relatively low (approximately 5 mPa · s or less), it is not always necessary to use a cleaning agent, and it is possible to introduce ink with air bubbles removed even if ink is introduced from the ink solvent. It is. Further, the ink-jet device may be terminated by filling the ink solvent during the termination operation of the inkjet apparatus.

  Even during the maintenance of the recording head 1 (surface cleaning mode, ultrasonic cleaning mode), if the viscosity of the ink solvent for ink application is relatively low, it is not always necessary to use a cleaning agent. Surface cleaning or ultrasonic cleaning may be performed.

FIG. 3 is a diagram illustrating a recording head maintenance method according to an embodiment of the present invention. 3 is a flowchart for executing a recording head maintenance method according to an embodiment of the present invention. 3 is a flowchart for executing a recording head maintenance method according to an embodiment of the present invention. It is a side view which shows the outline | summary of the inkjet apparatus to which this invention is applied. It is a front view which shows the outline | summary of the inkjet apparatus to which this invention is applied. FIG. 3 is a diagram illustrating an ink supply unit and a recording head maintenance unit according to an embodiment of the present invention. It is a figure explaining the ink supply method to the recording head in the ink application | coating preparation stage which is one Example of this invention. It is a figure explaining the ink supply method to the recording head at the time of the ink application which is one Example of this invention. FIG. 4 is a diagram illustrating a cleaning liquid supply method to a cap during cleaning of an orifice surface of a recording head according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a recording head cleaning unit according to an embodiment of the present invention. It is a figure explaining the cap of the recording head which is one Example of this invention. FIG. 5 is a diagram illustrating a method for cleaning an orifice surface of a recording head according to an embodiment of the present invention. It is a figure explaining the state of the water head pressure at the time of the ink application which is one Example of this invention. It is a figure explaining the state of the hydraulic head pressure at the time of measuring the flow volume of the recording head which is one Example of this invention. It is a figure explaining the washing | cleaning liquid supply method at the time of ultrasonic cleaning of the recording head which is one Example of this invention. It is a figure explaining the ultrasonic cleaning method of the recording head which is one Example of this invention. It is a figure which shows the method of observing the discharge state of the ink which is one Example of this invention. FIG. 5 is a diagram illustrating a criterion for determining an abnormal state of a recording head according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording head 2 Cleaning agent bottle 3 Ink solvent bottle 4 First ink bottle 5 Second ink bottle 6 First collection bottle 7 Second collection bottles 11-16 Air pumps 17, 18 Water pumps 21-25 Three-way valve

Claims (10)

Inkjet including a transport device for transporting a medium to be coated, a plurality of ink bottles containing ink in which particles are dispersed, a recording head for coating the ink on the medium to be coated, and a carriage for moving the recording head In the device
Means for applying ink to the ink in which the particles are dispersed at the time of non-ink application from the first ink bottle through the recording head to the second ink bottle to flow the ink, and detecting the ink flow rate at that time; ,
Means for detecting the ink ejection state during non-ink application;
Means for selecting and executing a plurality of recording head maintenance methods to be executed in order to keep the application state of the recording head stable according to the detection result of the ink flow rate and the detection result of the ink discharge state; An ink jet apparatus comprising: The inkjet apparatus according to claim 1.
When pressure is applied from the first ink bottle to the second ink bottle via the recording head, ink leaks from the recording head to the first and second ink bottles. An ink jet apparatus having means for setting no pressure. The inkjet apparatus according to claim 1.
The ink jet apparatus according to claim 1, wherein the means for detecting the ink discharge state calculates the ink discharge state by a sum of the number of defects and the number of discharge bends. The inkjet apparatus according to claim 1.
An inkjet apparatus comprising: a determination table for determining an abnormality degree according to the detection result of the ink flow rate and the detection result of the ink discharge state. The inkjet apparatus according to claim 1.
A plurality of recording head maintenance methods include at least a method of bringing a cap into contact with the recording head and sucking the liquid inside the recording head, a method of pressurizing and filling the recording head with ink, and ejecting ink from the orifice, and the cap The cleaning liquid is sent into the cap, the cap and the recording head are brought close to each other, the recording head orifice surface is cleaned, and the recording head orifice surface is immersed in an ultrasonic cleaning tank, and the recording head is ultrasonically cleaned. An ink jet apparatus, comprising: The inkjet apparatus according to claim 5.
The means for selecting and executing the plurality of recording head maintenance methods can be executed in a shorter time as the degree of abnormality determined according to the detection result of the ink flow rate and the detection result of the ink discharge state is lighter. An ink jet apparatus, wherein a recording head maintenance method is selected. The inkjet apparatus according to claim 6.
An ink jet apparatus comprising: means for detecting an ink ejection state after executing recording head maintenance and repeating the recording head maintenance if the ink ejection state does not return to a normal state. The inkjet apparatus according to claim 7.
An ink jet apparatus comprising: means for executing a recording head maintenance method that requires a longer time than the maintenance method when the ink ejection state does not return to a normal state even if the same maintenance method is repeated a plurality of times. In the ink jet device according to any one of claims 6 to 8,
An ink jet apparatus comprising: a memory for recording at least a date and time of execution, a recording head maintenance method, and a number of executions when an ink discharge state is detected after execution of recording head maintenance and the state returns to a normal state. The ink jet apparatus according to claim 9.
An ink jet apparatus comprising: a recording head maintenance method; and a display unit that displays information related to a recording head replacement time based on a history of the number of executions.

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