JP2008289983A - Ink jet device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet device capable of highly precisely and highly stably discharging ink even in the case of the ink having various properties from solid-liquid ink having an anxiety for flocculation and settlement on down. <P>SOLUTION: An ink jet device can be provided in which the effect of pressure fluctuation in an ink jet head accompanying ink jet head driving conditions and an ink circulating flow rate is suppressed, and the ink can be highly precisely and highly stably discharged even in the case of the ink having various physical properties by installing a ink feed-recovery condition-control means variably controlling the pressure set values of a feed ink tank and a recovery ink tank through detecting the pressure in the ink jet head with a pressure sensor or through calculating the pressure in the ink tank head with such conditions as discharge information and an ink flow rate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet apparatus that ejects ink onto a medium. More specifically, the present invention relates to various types of detection and control in an ink supply unit to the ink jet head and an ink recovery unit from the ink jet head that enable stable ejection of various ink materials by the ink jet head. The ink according to the present invention is not limited to printing on a medium such as paper, but also includes a general fluid and a solid-liquid mixed fluid in which solid particles are dispersed in the fluid.

  Currently, ink jet recording apparatuses are widely used as output means of information processing systems. These ink jet apparatuses eject fine droplets from nozzles to print or draw characters or figures on a recording medium such as paper.

  In recent years, this ink-jet technology has come to be used as a technology for various industrial manufacturing apparatuses including metal wiring formation on a circuit board and a color filter for display.

  In an industrial inkjet apparatus, an ejection operation using ink having various physical properties different from those of conventional image recording inks is required. Furthermore, in various industrial manufacturing apparatuses, unlike conventional image recording apparatuses, a discharge operation to a very large size is required. For example, in a manufacturing apparatus applied to the field of flat panel displays such as liquid crystal and plasma, recording in an area of several m square or more is required.

  The ink jet apparatus includes an ink tank that stores ink, an ink jet head that discharges ink while adjusting the ink, and a carriage that moves the ink jet head on a recording medium. In a general ink jet apparatus, an ink tank is provided on the upper side of the ink jet head, and ink is supplied by a water head difference.

  In industrial large-scale inkjet devices, the amount of ink consumed is large, and the ink tank is inevitably large. Along with this, a large-capacity ink tank is required, and the water head difference between the ink tank and the inkjet head greatly changes depending on the remaining amount of ink. Further, when a large-capacity ink tank is arranged above the ink jet head, a large positive pressure is applied to the ink jet head, and ink leakage from the nozzle portion of the ink jet head occurs.

  Therefore, there are known a method of arranging the ink tank on the housing side of the main body and a method of dividing the ink tank into a large-capacity main tank and a small-capacity sub-tank and arranging only the sub-tank on the carriage. However, when these methods are applied to industrial large-scale inkjet devices, the length of the flexible tube connecting the tank installed on the housing side to the sub-tank or inkjet head on the carriage becomes very long. It is necessary to fill a large amount of ink inside, and a large amount of ink is wasted at start-up, stop, and ink replacement.

  As a method for securing an appropriate ink pressure to the ink jet head with the ink tank placed on the carriage, the ink jet head includes a first ink tank connected to the ink jet head and a large capacity second ink tank. There is a method of adjusting the pressure of ink supplied to an inkjet head by providing a negative pressure generating means in a first ink tank to be connected (see, for example, Patent Documents 1 and 2).

JP 2003-266734 A JP 2006-62329 A

  As described above, an industrial inkjet apparatus requires an ejection operation using inks having various physical properties different from those of conventional image recording inks. Further, a highly accurate and highly stable discharge operation is required.

  In order to eject ink with high accuracy using an inkjet head, it is very important to properly maintain the shape (meniscus) of the liquid level at the minute port (orifice port) provided to eject the ink. . If the pressure in the inkjet head is too high, ink leaks, and if the pressure is too low, the meniscus is destroyed and air is sucked. In order to eject the ink straight, it is ideal that the meniscus is slightly recessed in the head, and it is essential for a highly accurate and highly stable ejection operation to stably and maintain this.

  The pressure in the ink jet head that maintains such an appropriate meniscus state is a delicate set value of a weak negative pressure condition of about several hundred Pa with respect to atmospheric pressure. The required accuracy and appropriate range vary depending on the conditions of the ink used.

  In an industrial inkjet apparatus that requires highly accurate and highly stable discharge operation with ink having various physical properties, it is necessary to control the pressure in the head with high accuracy in order to perform highly accurate meniscus control.

  However, in an industrial inkjet apparatus that requires a large amount of ink ejection at a high speed, a large amount of ink is sent from the supply ink tank to the inkjet head, and this causes a pressure drop caused by the ink flow rate. There arises a problem that the pressure in the ink jet head is further reduced. In addition, since the pressure drop varies depending on the driving conditions of the ink jet head and the like, high-precision pressure control in the ink jet head cannot be realized only by the conventional set pressure control of the supplied ink tank.

  Furthermore, as an ink for industrial inkjet, a solid-liquid mixed ink in which a dispersing agent such as a solid particulate member is dispersed in a solution is also used. Such an ink causes agglomeration or sedimentation of dispersed particles when the ink is stagnated. Therefore, it is necessary to always stir and flow the ink at a constant flow rate.

  In order to prevent aggregation and settling of dispersed particles in the ink, a method of circulating and supplying ink from the ink tank to the inkjet head can be considered. In this case, the ink flow rate from the supply ink tank to the ink jet head is further increased, and a larger pressure fluctuation or reduction occurs, making pressure control within the ink jet head, that is, meniscus control, more difficult.

  In the methods described in Patent Documents 1 and 2, sufficient pressure control in the ink jet head, that is, meniscus control cannot be performed under these circumstances.

  An object of the present invention is to provide an ink jet apparatus that can discharge ink with high accuracy and high stability even for inks having various physical properties such as solid-liquid dispersed inks that are a concern of aggregation and sedimentation.

  In order to achieve the above object, the ink jet apparatus is configured as described in (1) or (2) below.

  (1) In-head pressure detecting means for detecting the pressure in the ink flow path in the head of the inkjet head that ejects ink, a supply ink tank that is connected to the inkjet head and supplies ink to the inkjet head, and the supply Supply ink tank pressure control means for controlling the pressure in the ink tank to a set value, and ink supply condition control means for variably controlling the pressure set value of the supply ink tank pressure control means according to the detection value of the head internal pressure detection means Prepared.

  (2) In-head pressure detecting means for detecting the pressure in the ink flow path in the head of the inkjet head, a supply ink tank connected to the inkjet head and storing ink to be supplied to the inkjet head, and the supply ink tank Supply ink tank pressure control means for holding the internal pressure at a set value, a recovery ink tank that is connected to the inkjet head by piping, collects ink in the inkjet head, and stores the recovered ink, and the recovered ink tank Ink supply for controlling the set value of the supply ink tank pressure control means and the recovery ink tank pressure control means by the detected value of the head internal pressure detection means and the recovered ink tank pressure control means for holding the internal pressure at the set value A recovery condition control means was provided.

  In a preferred embodiment of the present invention, in the above-described ink jet apparatus of (1) or (2), the head pressure detection means comprises a pressure sensor connected to the ink jet head by piping, and the ink flow rate between the ink jet head and the pressure sensor. Is configured to detect pressure with substantially zero.

  In another preferred embodiment, in the ink jet apparatus of the above (1), the head internal pressure detecting means includes the set pressure of the supply ink tank pressure control means, the amount of ink ejected per unit time in the ink jet head, or the ink of the head. The pressure value in the inkjet head is calculated using at least one of the ejection conditions and the ink supply flow rate to the inkjet head.

  In another preferred embodiment, in the ink jet apparatus of the above (2), the head internal pressure detecting means includes the set pressures of the supply ink tank pressure control means and the recovered ink tank pressure control means, and units in the ink jet head. The pressure value in the ink jet head is calculated using at least one of the ink discharge amount per time or the ink discharge conditions of the head, the ink supply flow rate to the ink jet head, and the ink recovery rainfall amount. .

  In another preferred embodiment, an ink flow rate detection unit capable of detecting at least one of an ink supply flow rate from the supply ink tank to the inkjet head or an ink recovery flow rate from the inkjet head to the recovery ink tank is provided.

  In another preferred embodiment, an ink return transport path and a return transport pump for returning ink from the recovered ink tank toward the supply ink tank are provided.

  In another preferred embodiment, at least one of the supply ink tank and the recovery ink tank includes detection means capable of detecting at least one of the ink liquid surface height, the ink liquid amount, and the ink liquid weight in the tank. Configured to do.

  In another preferred embodiment, an opening / closing valve capable of opening and closing the pipe is provided in at least one of the supply ink tank, the head internal pressure detection means, and the recovery ink tank connected to the inkjet head by a pipe.

  The ink used in the present invention described above can be a solid-liquid mixed ink in which solid particulate members are dispersed in a solution.

  The ink jet apparatus of the present invention detects the pressure in the ink jet head and variably controls the pressure setting value of the ink supply ink tank. Stable ink pressure control, i.e. meniscus control, is possible without being affected by pressure drop.

  Thereby, it is possible to provide an ink jet apparatus capable of ejecting ink having various physical properties such as solid-liquid dispersed ink, which is concerned about aggregation and sedimentation, with high accuracy and high stability.

  In addition to the supply ink tank, the supply ink tank pressure control means, and the in-head pressure detection means, the supply ink tank includes a recovery ink tank, a recovery ink tank pressure control means, and an ink supply recovery condition control means. In addition to controlling the internal pressure of the inkjet head, the circulating flow rate supplied to the inkjet head can be controlled according to the difference between the pressure settings of the supply ink tank and the recovered ink tank. In addition, the aggregation and dispersion prevention of dispersed particles in the ink can be realized efficiently and stably.

  By using a pressure sensor connected to the inkjet head as a pressure detection means in the inkjet head, the inkjet head is configured to detect pressure in a state where the ink flow rate between the inkjet head and the pressure sensor is almost zero. And the pressure loss between the pressure sensors is eliminated, and the pressure in the inkjet head can be detected with high accuracy.

  Further, as other ink jet head internal pressure detection means, the set pressures of the supply ink tank pressure control means and the recovered ink tank pressure control means, the amount of ink ejected per unit time in the ink jet head or the ink ejection conditions of the head, the ink jet By providing an in-head pressure calculation detecting means for calculating a pressure value in the inkjet head using at least one of the supply flow rate and the recovery flow rate to the head, a pressure sensor is not installed in the inkjet head. The pressure in the inkjet head can be calculated.

  For this purpose, it is desirable to provide a ink flow rate detecting means that cannot detect at least one of the ink supply flow rate from the supply ink tank to the ink jet or the ink recovery flow rate from the ink jet to the recovery ink tank.

  The pressure in the ink jet head is determined by the pressure change due to the ink flow rate with respect to the pressure setting values of the supply ink tank and the recovery ink tank. By accurately measuring the ink volume, supply flow rate, and recovery flow rate that the inkjet head discharges per unit time, the pressure loss from the supply ink tank to the inkjet head and the ratio of pressure loss from the inkjet head to the recovery ink tank can be increased. Accurate ink head pressure can be calculated. Thereby, compared with the case where a pressure sensor is provided in an inkjet head, the control of ink by the apparatus, piping configuration, various valves, and the like is simplified.

  Further, the pressure applied to the ink jet head is detected with higher accuracy by detecting at least one of the ink liquid level height, the ink liquid amount or the ink liquid weight in the supply ink tank and the recovered ink tank. It becomes possible.

  Hereinafter, specific embodiments of the present invention will be described with reference to FIGS. 1 to 3.

  In the present embodiment, a case will be described in which an ink supply system and a recovery system are provided and a pressure sensor is provided as an in-head pressure detection means.

  FIG. 1 is a diagram for explaining the overall configuration of an inkjet head and an ink supply / recovery system in an inkjet apparatus according to the present invention. The ink jet apparatus includes an ink jet head 12, an ink supply system 10, an ink recovery system 15, and ink supply / recovery condition control means 1.

  The ink supply system 10 includes a supply ink tank 8 for storing ink, a supply ink stirring device 9 for stirring ink, a supply ink tank pressure sensor 6 for detecting ink pressure in the supply ink tank, and a liquid level in the supply ink tank. The supply ink tank liquid level sensor 5 for detecting the height, the supply ink tank internal pressure control pump 7 for controlling the pressure in the supply ink tank, the supply ink tank pressure sensor 6 and the supply ink tank liquid level sensor 5 A supply ink tank pressure control means 4 for controlling the water head pressure in the ink tank is configured.

  The head pressure in the supply ink tank indicates the relative supply head pressure when the nozzle surface of the ink jet head is used as a reference. The head pressure increases as the liquid level in the supply ink tank increases, and decreases as the position decreases. . As the operation of the supply ink tank pressure control means 4, the pressure in the supply ink tank 8 is changed to the supply ink tank pressure sensor 6 and the supply ink tank internal pressure control pump according to the change of the liquid level in the supply ink tank 8. 7 is controlled so as to keep the water head pressure in the supply ink tank 8 constant.

  The supply ink stirring device 9 provided in the supply ink tank 8 is provided to prevent sedimentation and aggregation of the dispersant in the solid-liquid mixed ink in which the solid particulate member is dispersed in the solution. In the case of ink that does not change the characteristics of the ink without stirring, the supply ink stirring device 9 may not be provided.

  The supply ink agitating device 9 agitates the ink by rotating it. However, if the rotation is made too fast, the generation of bubbles in the ink and the control of the head pressure in the supply ink tank 8 may become unstable. The rotational speed needs to be set in consideration of these points. When the ink head pressure control or the ink ejection operation is affected by the ink physical properties, the supply ink stirring device 9 may be required to be stopped during the ink head pressure control or the ink ejection operation.

  The ink recovery system 15 has basically the same configuration as the ink supply system 10, and includes a recovery ink tank 17 that stores ink, a recovery ink stirring device 16 that stirs ink, and an ink pressure in the recovery ink tank 17. Is a recovery ink tank pressure sensor 19 for detecting the liquid level, a recovery ink tank liquid level sensor 20 for detecting a liquid level in the recovery ink tank, a recovery ink tank internal pressure control pump 18 for controlling the pressure in the recovery ink tank, and a recovery ink tank. Based on detection values of the pressure sensor 19 and the recovery ink tank liquid level sensor 20, the recovery ink tank pressure control means 21 controls the head pressure in the recovery ink tank.

  The ink recovery system 15 is also controlled by the recovery ink tank pressure control means 21 so as to keep the head pressure in the recovery ink tank 17 constant under the same control as the ink supply system 10.

  It goes without saying that the recovered ink stirring device 16 provided in the recovered ink tank 17 also needs to be controlled in the same way as the supplied ink stirring device 9 provided in the supplied ink tank 8.

  Next, an actual application operation will be described.

  In the actual application operation, the ink head flows from the supply ink tank 8 to the recovery ink tank 17 by setting the water head pressure setting value Ps of the supply ink tank 8 and the water head pressure setting Pc of the recovery ink tank 17 to Ps> Pc. start. At this time, the water head pressure Ph in the inkjet head 12 is Ps> Ph> Pc. Ph is affected by a pressure loss from the supply ink tank 8 to the ink jet head 12 and a pressure loss from the ink jet head 12 to the recovered ink tank 17. These pressure losses are affected by the pipe line configuration, flow velocity, ink physical properties, and the like.

  FIG. 2 is an example of a result of measuring a change in the water head pressure in the inkjet head 12 when the inkjet discharge operation is performed. The pressure in the ink jet head is lowered by the ejection operation, but the degree of the reduction is affected by the ejection frequency and the ink type that affect the ink flow rate. FIG. 2 schematically shows a change in water head difference during continuous ejection at the ejection frequencies of 3 kHz and 6 kHz in the low viscosity ink, the high viscosity ink, and the high viscosity solid-liquid mixed ink.

  The pressure change in the inkjet head 12 affects the ink ejection accuracy and operation. In particular, when the pressure in the ink jet head 12 decreases to a certain extent, a problem such as stopping the ink ejection operation occurs due to entrainment of bubbles.

  In the configuration of the present invention shown in FIG. 1, the pressure in the inkjet head 12 is directly detected by providing the inkjet head 12 with the inkjet head internal pressure sensor 11, and the ink supply / recovery condition control means 1 supplies the supply ink tank pressure. By variably controlling the set pressures of the control means 4 and the recovered ink tank pressure control means 21, it is possible to control the pressure inside the inkjet head 12 to be maintained within an appropriate range regardless of the ejection frequency and the type of ink. I have to.

  The ink jet head pressure sensor 11 connected to the ink jet head 12 is connected to the ink recovery path piping to the recovery ink tank 17 by the three-way valve 14 together with the ink jet head 12.

  It is desirable that the pressure sensor 11 in the ink-jet head is subjected to pressure measurement in a state in which the connection between the ink recovery path piping and the flow velocity between the ink-jet head 12 and the ink-jet head pressure sensor 11 is zero.

  This is because, when there is a flow velocity between the inkjet head 12 and the inkjet head internal pressure sensor 11, a pressure loss in the connection path causes a difference between the pressure in the inkjet head 12 and the detected pressure of the inkjet head internal pressure sensor 11. This is because the pressure in the inkjet head 12 cannot be measured accurately.

  If the flow velocity difference between the inkjet head 12 and the inkjet head pressure sensor 11 is 1/0 or less, there is no problem in terms of measurement accuracy, and preferably the difference is 1/100 or less. It is better to measure the pressure at

  However, the ink supplied from the inkjet head 12 to the pressure sensor 11 in the inkjet head can be recovered by opening the three-way valve 11 when not measuring. This is important for inks where there is concern about sedimentation or aggregation of the dispersant, such as solid-liquid mixed ink in which solid particulate members are dispersed in a solution, and the inkjet head 12 and inkjet head internal pressure sensor 11 are regularly used. It is necessary to circulate and collect ink such as the flow path between them.

  In the embodiment of FIG. 1, the pressure sensor 11 in the inkjet head is connected to the recovery path pipe by a three-way valve 14, but the same effect can be obtained when this is connected to the supply path pipe by a three-way valve. be able to.

  The optimum amount of ink supplied to the inkjet head 12 and the amount of circulation are determined by the ink physical properties such as the dispersant for the ink used and the application conditions such as the discharge frequency and discharge interval. The optimum ink supply / circulation amount is determined by the difference between the control head pressure Ps of the supply ink tank and the control head pressure Pc of the recovered ink tank.

  In order to keep the internal pressure in the ink jet head 12 properly while controlling the ink circulation amount to the ink jet head 12 to a predetermined amount, the value of the pressure sensor 11 in the ink jet head arranged in the ink jet head 12 is kept constant. In addition, it is necessary to variably control the set pressure of the supply ink tank 8 and to perform control so that the difference between the set pressure values of the supply ink tank 8 and the recovered ink tank 17 is constant so that an appropriate circulating ink flow rate is obtained. is there. In the present embodiment of FIG. 1, the ink supply / recovery condition control means 1 uses the detected values of the ink-jet head pressure sensor 11 provided in the ink-jet head 12 to set the set pressures of the supply ink tank 8 and the recovered ink tank 17. This can be realized by independent variable control.

  Further, the supply amount and the circulation amount to the ink jet head 12 are the change in the liquid amount by the supply ink tank liquid level sensor 5 and the recovery ink tank liquid level sensor 20 that detect the liquid levels of the supply ink tank 8 and the recovery ink tank 17. It can be detected and calculated from the control information of the ejection operation, that is, the inkjet head drive information 2. The ink supply / recovery condition control means 1 is configured to accurately control the pressure in the ink jet head and the ink supply amount and the circulation amount to the ink jet head based on these pieces of information.

  In order to prevent ink leakage from the nozzles of the inkjet head 12 when the apparatus is started up, stopped, or maintained, the supply ink tank 8 and the recovered ink tank 9 connected to the inkjet head 12 and the inside of the inkjet head An opening / closing valve 13 is provided in a pipeline such as the pressure sensor 11.

  In the conditions such as the start-up of the device and the start-up process, basically, these on-off valves are closed to cause ink leakage from the nozzles and air suction due to improper pressure applied to the inkjet head. To prevent malfunctions. The same applies not only to startup, but also to operations such as the maintenance operation of the ink jet head and its nozzles and the stop sequence of the apparatus, and the transition to these operation modes.

  As an example of the maintenance operation, the pressure sensor 11 in the inkjet head and the on-off valve 13 to the recovered ink tank 17 are closed, and the pressurized water head pressure in the supply ink tank 8 is increased, so that the ink is pressed from the nozzle of the inkjet head 12. The pressure purge operation to be performed, the ink jet head internal pressure sensor 11 and the on-off valve 13 to the supply ink tank 8 are closed, and the water head pressure of the recovered ink tank 17 is greatly reduced to suck out ink from the nozzles. Thus, there is an operation such as a suction purge for eliminating clogging of the inkjet head 12 and its nozzles. In these maintenance operations, the control operation of each on-off valve 13 as described above is required.

  In the embodiment shown in FIG. 1, the ink jet head 12 can perform the discharge operation while circulating ink from the supply ink tank 8 to the recovery ink tank 17, but the ink is discharged toward the recovery ink tank 17 at the time of ink discharge. It is also possible to control by the ink supply / recovery condition control means 1 so that the ink circulation flow rate becomes zero. In this case, the water head pressure setting value of the recovered ink tank 17 is set to be the same as the water head pressure of the ink jet head 12 or the on-off valve of the conduit to the recovered ink tank 17 is closed. In this way, by making the ink circulation flow rate toward the recovered ink tank 17 zero during ink ejection, more accurate pressure control within the inkjet head 12 is possible.

  Further, as shown in FIG. 1, in the configuration in which ink is circulated from the supply ink tank 8 to the recovery ink tank 17, the ink recovered in the recovery ink tank 17 is returned to the supply ink tank 8 in consideration of the ink use efficiency. It is necessary. For this purpose, in FIG. 1, an ink return pump 3 for returning the ink in the recovered ink tank 17 to the supply ink tank 8 is arranged.

  However, since the operation of the ink return pump 3 affects the water head values of the ink supply system 10 and the ink recovery system 15, the control accuracy may be lowered. In order to control the water head pressure in the inkjet head 12 during ink ejection with higher accuracy, it is important to control the water head values of the ink supply system 10 and the ink recovery system 15 with high accuracy. If more precise water head pressure control is required, control such as stopping the operation of the ink return pump 3 is also required during ink ejection. The actual control sequence details must be defined in consideration of the physical properties of the ink to be used, the discharge conditions of the inkjet head 12, and the like.

  The ink jet device is a device start-up mode that supplies initial ink to the ink jet head, a recording mode that drives the ink jet head in accordance with operation information to perform ink discharge operation, a maintenance mode that performs maintenance such as cleaning of the ink jet head, and device stop Therefore, the apparatus has a plurality of operation modes such as a device stop mode for collecting ink in the ink jet head. In each of these modes, at least one of the head internal pressure detection means, the ink flow rate detection means, the supply ink tank, and the recovery ink tank liquid amount detection means is detected, and the supply ink tank, the head internal pressure detection means, and the recovery ink are detected. It is necessary to variably control at least one of the connection piping on-off valve of the tank, the set pressure of the supply ink tank, and the set pressure of the recovered ink tank. Therefore, the ink jet apparatus according to the present invention has an operation mode for this purpose. It is desirable to have a control means.

  In FIG. 1, an ink jet head pressure sensor 11 for measuring the pressure in the ink jet head 12 is arranged. However, even when the pressure sensor is not provided, the present invention can be implemented by the following means.

  In this embodiment, attention is paid to the fact that the pressure in the ink jet head 12 differs from the set pressure of the ink supply system 10 and the ink recovery system 15 and fluctuates. The difference between the pressure in the ink jet head 12 and the set pressure of the ink supply system 10 and the ink recovery system 15 is caused by the pressure loss in the ink supply system pipe, the ink recovery system pipe and the ink jet head 12, and the ink flowing through them. This is due to the flow rate. These pressure losses depend on the ink physical properties and the properties of the conduit and the flow velocity flowing therethrough.

  For this reason, it is possible to calculate the pressure in the ink jet head with respect to the set pressure of the ink supply system 10 and the ink recovery system 15 from the circulating ink flow rate, the ejected ink flow rate, the ink physical property change, and the like.

  However, since the ink jet head internal pressure value with respect to the set pressure of the ink supply system 10 and the ink recovery system 15 is a complex function, in order to realize a more accurate calculation of the ink jet head internal pressure, the actual ink supply system In addition, a method of creating a conversion matrix by referring to the multi-point measurement in advance with respect to the pressure inside the inkjet head with respect to the setting conditions of the ink recovery system and referring to this is effective.

  In FIG. 1, an ink supply system 10 and an ink recovery system 15 are provided. This configuration is suitable for ejecting ink that is very difficult to handle, such as solid-liquid dispersed ink, where aggregation or sedimentation is a concern, with high accuracy and high stability.

  Ink that is relatively easy to handle, such as one-component or low-viscosity ink, does not require an ink circulation system. In such a case, the ink recovery system 15 in the configuration of FIG. 1 is unnecessary, and the configuration of the ink supply system is simplified. In this case, the ink supply / recovery condition control means 1 in FIG. 1 is replaced with an ink supply condition control means.

  Even in such a configuration, there is a difference in the ink flow rate from the supply ink tank 8 to the inkjet head 12 under the ink discharge conditions, so that the set pressure of the supply ink tank that keeps the pressure in the inkjet head 12 constant. Control is necessary, and the set pressure of the supply ink tank pressure control means 4 is variably controlled by the ink supply condition control means. As for the pressure in the ink jet head 12, any method of calculating from the pressure sensor 11 in the ink jet head arranged in the ink jet head 12 or the discharge flow rate can be applied.

  FIG. 3 shows the overall configuration of an ink jet apparatus equipped with the ink supply and recovery system of the present invention.

  A gate-type inkjet head guide rail 26 straddling the stage 22 is disposed on the stage 22. The moving table 23 on the stage 22 is configured to move in a direction passing through the portal-type inkjet head guide rail 26, that is, in a table moving direction 29.

  The ink jet system 25 is installed on a portal guide rail and is configured to be movable in an ink jet head moving direction 28 orthogonal to the table moving direction 29 of the moving table 23 on the stage 22.

  The ink jet head 12 mounted on the ink jet system 25 is installed close to the application target substrate 24 disposed on the moving table 23 of the stage 22 with a gap of several hundred μm.

  Ink supply / recovery systems such as the supply ink tank 8 and the recovery ink tank 17 are arranged above the ink jet head 12. The ink jet head 12 and the ink jet head guide rail 26 are orthogonal to the table moving direction 29 together with the ink jet head 12. Move in the direction you want.

  In the actual coating operation, the substrate to be coated 24 is placed on the moving table 23 of the stage 22, and after moving the inkjet head 12 to a predetermined position, the inkjet head 12 is ejected while moving the moving table 23. Apply. Next, the inkjet head 12 is moved to the next application position, the same operation is repeated, and a planar application operation is performed on the application target substrate 24 fixedly arranged on the moving table 23.

  Next to the stage 22 in FIG. 3, an ink jet device control operation unit 27 for controlling and operating the entire ink jet device of the present invention is disposed.

  In the configuration of this embodiment, since the ink pressure in the inkjet head 12 during the application operation can be strictly adjusted, ink having various physical properties such as solid-liquid dispersed ink, which is a concern about aggregation and sedimentation, is used. In addition, it is possible to provide an ink jet apparatus that can discharge with high accuracy and high stability.

It is a figure which shows one Example of the whole structure of the inkjet head and ink supply collection system in the inkjet apparatus of this invention. It is the figure which showed an example of the result of having measured the water head pressure change in the inkjet head when an inkjet discharge operation | movement was carried out. 1 is a diagram illustrating an overall configuration of an ink jet apparatus equipped with an ink supply and recovery system of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ink supply collection condition control means, 2 ... Inkjet head drive information, 3 ... Ink return pump, 4 ... Supply ink tank pressure control means, 5 ... Supply ink tank liquid level sensor, 6 ... Supply ink tank pressure sensor, 7 ... Supply ink tank internal pressure control pump, 8 ... Supply ink tank, 9 ... Supply ink stirring device, 10 ... Ink supply system, 11 ... Inkjet head internal pressure sensor, 12 ... Inkjet head, 13 ... Open / close valve, 14 ... Three-way valve, 15 DESCRIPTION OF SYMBOLS ... Ink collection system, 16 ... Collected ink stirring device, 17 ... Collected ink tank, 18 ... Collected ink tank internal pressure control pump, 19 ... Collected ink tank pressure sensor, 20 ... Collected ink tank liquid level sensor, 21 ... Collected ink tank pressure Control means, 22 ... stage, 23 ... moving table, 24 ... substrate to be coated, 25 ... ink jet Collection system, 26 ... Gate inkjet head guide rail, 27 ... inkjet device control operation unit, 28 ... inkjet head moving direction, 29 ... table moving direction.

Claims (12)

  In an inkjet apparatus including an inkjet head that ejects ink and a supply ink tank that is connected to the inkjet head and stores ink supplied to the inkjet head, the pressure in the supply ink tank is maintained at a set value. Supply ink tank pressure control means, head internal pressure detection means for detecting the pressure in the ink flow path in the head of the inkjet head, and pressure setting of the supply ink tank pressure control means based on the detection value of the head internal pressure detection means An ink jet apparatus comprising ink supply condition control means for controlling a value.   In an inkjet apparatus including an inkjet head that ejects ink and a supply ink tank that is connected to the inkjet head and stores ink supplied to the inkjet head, the pressure in the supply ink tank is maintained at a set value. Supply ink tank pressure control means, head internal pressure detection means for detecting the pressure in the ink flow path in the head of the ink jet head, and piping connected to the ink jet head, recover the ink in the ink jet head, and recover the ink A collected ink tank for storing the collected ink, a collected ink tank pressure control means for holding the pressure in the collected ink tank at a set value, a supply ink tank pressure control means and a pressure value detected by the pressure detection means in the head. Controls the set value of the recovered ink tank pressure control means Jet apparatus characterized by comprising an ink supply recovery condition control means that.   3. The ink jet apparatus according to claim 1 or 2, wherein the pressure detecting means in the head is a pressure sensor connected to the ink jet head by piping, and the ink flow rate between the ink jet head and the pressure sensor is substantially zero. An ink jet apparatus configured to detect pressure.   2. The ink jet apparatus according to claim 1, wherein the head internal pressure detection means includes a set pressure of the supply ink tank pressure control means, an ink discharge amount per unit time in the ink jet head or an ink discharge condition of the head, the ink jet An ink jet apparatus for calculating a pressure value in an ink jet head using at least one value of an ink supply flow rate to the head.   3. The ink jet apparatus according to claim 2, wherein the head internal pressure detection means includes a set pressure of each of the supply ink tank pressure control means and the recovered ink tank pressure control means, and a discharge ink per unit time in the ink jet head. The pressure value in the ink jet head is calculated using at least one of an amount or an ink discharge condition of the head, an ink supply flow rate to the ink jet head, and an ink recovery flow rate. apparatus.   3. The ink flow rate detection method according to claim 2, wherein at least one of an ink supply flow rate from the supply ink tank to the inkjet head and an ink recovery flow rate from the inkjet head to the recovery ink tank can be detected. An ink jet apparatus comprising means.   3. The ink jet apparatus according to claim 2, further comprising an ink return transport path and a return transport pump for returning ink from the recovered ink tank toward the supply ink tank.   2. The ink jet apparatus according to claim 1, further comprising detection means capable of detecting at least one of an ink liquid surface height, an ink liquid amount and an ink liquid weight in the tank of the supply ink tank. Inkjet device.   3. The ink jet apparatus according to claim 2, further comprising detection means capable of detecting at least one of the height of ink liquid level, the amount of ink liquid, and the weight of ink liquid in the tank of the supply ink tank and the recovered ink tank. An inkjet apparatus characterized by that.   2. The ink jet apparatus according to claim 1, wherein an opening / closing valve capable of opening and closing the pipe is provided in at least one of the supply ink tank connected to the ink jet head and the pressure detecting means in the head. An inkjet apparatus.   3. An on-off valve capable of opening and closing a pipe in at least one of the supply ink tank, the head internal pressure detection means, and the recovered ink tank connected to the ink jet head by piping. An inkjet apparatus comprising:   The ink jet apparatus according to claim 1 or 2, wherein the ink used is a solid-liquid mixed ink in which solid particulate members are dispersed in a solution.

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