JP2010046851A - Ink ejecting device and ink pressure softening method - Google Patents

Abstract

An ink pressure buffering mechanism is installed to suppress an unexpected pressure change with respect to ink inside an ink supply pipe connected to the ink discharge head or the head due to acceleration / deceleration or vibration of the ink discharge head, and To provide an ink discharge device and an ink pressure buffering method capable of accurately performing the meniscus control function of the ink discharge head of the ink supply mechanism.
The ink pressure buffering mechanism includes a flexible member for suppressing fluctuations in ink pressure, and a space portion installed so as to cover the flexible member. A valve for switching the sealing is provided.
[Selection] Figure 1

Description

  The present invention relates to an ink discharge head that uses an ink discharge recording method to discharge an ink from a nozzle hole of an ink discharge head to record an image or the like, and the ink discharge head is caused by acceleration / deceleration, vibration, or the like accompanying movement of the ink discharge head. In addition, the present invention relates to an ink discharge apparatus and an ink pressure buffering method provided with an ink pressure buffering mechanism capable of suppressing a change in ink pressure inside an ink supply pipe.

  Ink discharge methods of ink discharge heads using the widely used ink discharge recording method use a method using a piezoelectric element or an electrothermal conversion element as an discharge energy generating element used to discharge ink droplets. In any case, the ejection amount and ejection timing of ink droplets can be controlled by an electrical signal. Due to recent technological advances, printers and printing machines using these types of ink discharge heads are often used, and high-quality printing is required.

  When printing an image or the like with a printer or printing machine using an ink discharge recording method, the ink discharge head is reciprocated with respect to the print medium, and printing is performed for each fixed line, or the ink discharge head is stopped at a predetermined position. Various methods such as a method of moving the printing medium and performing printing are employed. However, when printing is performed line by line, the printing medium is moved while the ink ejection head is stationary during printing. Even when the ink discharge head is moved from the standby position to the printing position, or when the ink discharge head is moved to the maintenance position, it is necessary to move the ink discharge head. Due to vibration or the like, a pressure change occurs in the ink inside the ink discharge head and the ink supply pipe connected to the head.

  If an unexpected pressure change is applied to the ink inside the ink discharge head or the ink supply pipe, the meniscus cannot be maintained in the nozzle hole of the ink discharge head, and as a result, the ink discharged from the ink discharge head is bent (misdirected). ), Discharge failure due to air mixing into the nozzle hole, ink leakage from the nozzle hole, and the like, which cause a significant decrease in print quality. For this reason, in order to suppress the pressure change to the ink inside the ink discharge head or the ink supply pipe, there are many examples where an ink pressure buffering mechanism is attached to the ink supply pipe.

As an ink pressure buffering mechanism that suppresses ink pressure change, for example, as shown in Patent Document 1, an ink buffer unit is provided in an ink supply path, a part of which is covered with a flexible film film, and the film film is weighted. In addition to an ink pressure buffering mechanism for providing an effect as a damper and an ink supply pipe to the ink discharge head, an ink pipe communicating with the ink supply pipe and an ink liquid feeding means are provided to cancel the ink pressure. Various measures have been taken, such as an ink pressure buffer mechanism that suppresses ink pressure change by generating ink flow.
Japanese Patent No. 3804903

By the way, with the recent increase in size and quality of printing requirements, printers and printers that use ink ejection recording systems are equipped with more ink ejection heads, and each ink ejection head is ejected. There is a growing need to perform so-called meniscus control with high accuracy, which stabilizes the liquid surface shape at the discharge head nozzle hole before operating the energy generating element. For meniscus control, an ink supply mechanism that has a function of controlling the ink pressure and supplies ink to the ink discharge head at a constant pressure is required. The ink supply mechanism includes a container in which ink is stored, a pump for supplying ink from the container without excess or deficiency, such as a diaphragm pump, a tube pump, a turbine pump, and the like, and an ink discharge head nozzle in which a meniscus is formed It consists of a pressure sensor for measuring and monitoring the pressure in the hole and a signal processing unit for processing the signal from the pressure sensor and feeding it back to the drive command signal of the liquid feed pump. The performance is remarkably improved in order to cope with high quality.

  On the other hand, as described above, in order to suppress an unexpected pressure change with respect to the ink in the ink supply pipe connected to the ink discharge head or the head due to acceleration / deceleration or vibration accompanying the movement of the ink discharge head, It is also important to install a pressure buffering mechanism.

  However, if an ink pressure buffering mechanism for suppressing ink pressure change is installed in the ink supply pipe, the pressure change is excessively suppressed by the buffering effect, so the ink accompanying the high-precision meniscus control of the ink supply mechanism The fine pressure adjustment function is also absorbed, and meniscus control is hindered. As a result, there is a problem that quality defects such as density unevenness occur.

  An object of the present invention is to install an ink pressure buffering mechanism in order to suppress an unexpected pressure change with respect to ink in an ink supply pipe connected to the ink discharge head or the head due to acceleration / deceleration or vibration of the ink discharge head. The present invention also provides an ink discharge apparatus and an ink pressure buffering method capable of accurately performing the meniscus control function of the ink discharge head of the ink supply mechanism.

  In order to solve the above problems, the present invention employs the following configuration.

  The invention according to claim 1 is an ink discharge head, an ink supply mechanism for supplying ink to the ink discharge head at a constant pressure, an ink supply pipe connecting the ink discharge head and the ink supply mechanism, and an ink In an ink ejection apparatus that is installed in a supply pipe and includes an ink pressure buffering mechanism for suppressing ink pressure fluctuation, the ink pressure buffering mechanism includes a flexible member for suppressing ink pressure fluctuation, and a flexible An ink ejecting apparatus comprising a space portion installed so as to cover an adhesive member, and having a valve for switching communication / sealing with outside air in the space portion.

  A second aspect of the present invention is the ink ejection apparatus according to the first aspect, wherein the flexible member of the ink pressure buffering mechanism is a flexible tube.

  A third aspect of the present invention is the ink ejection apparatus according to the first aspect, wherein the flexible member of the ink pressure buffering mechanism is made of a flexible film.

  According to a fourth aspect of the present invention, the space portion installed so as to cover the flexible member of the ink pressure buffering mechanism is filled with a liquid. Ink ejection apparatus.

  According to a fifth aspect of the present invention, the liquid filled in the space portion installed so as to cover the flexible member of the ink pressure buffering mechanism is a non-volatile liquid. The ink discharge apparatus according to the above.

  The invention according to claim 6 is provided in a space portion of the ink pressure buffer mechanism installed so as to cover the flexible member, using the ink ejection device according to any one of claims 1 to 5. The ink pressure buffering method is characterized in that the effect of suppressing ink pressure fluctuation is switched between valid and invalid by opening and closing a valve.

  As described above, according to the present invention, an ink discharge head, an ink supply mechanism for supplying ink to the ink discharge head at a constant pressure, and an ink supply pipe connecting the ink discharge head and the ink supply mechanism And an ink discharge device provided with an ink pressure buffering mechanism for suppressing ink pressure fluctuations, installed in the ink supply pipe, in a space portion installed to cover the flexible member of the ink pressure buffering mechanism. If the ink pressure fluctuates due to acceleration / deceleration, vibration, etc. of the ink discharge head, the ink pressure buffer is opened by opening the valve installed in the space. The mechanism is effective, the ink pressure change is suppressed by the deformation of the flexible member, and when the ink discharge head is in the printing state, the valve installed in the space is sealed. Invalidates the click pressure buffer mechanism prevents deformation of the flexible member, without inhibiting the pressure control by the ink supply mechanism, it is possible to accurately perform the function of meniscus control of the ink jet head.

  An embodiment of the present invention will be described. FIG. 1 is a conceptual diagram showing an embodiment of an ink ejection apparatus according to the present invention. In FIG. 1, 1 is an ink discharge head, 2 is an ink supply mechanism for supplying ink at a constant pressure, 3 is an ink supply pipe connecting the ink discharge head 1 and the ink supply mechanism 2, and 10 is in the middle of the ink supply pipe 3 , An ink pressure buffering mechanism for suppressing ink pressure fluctuation, 20 is a printing medium, and 21 is a printing pattern ejected from the ink ejection head 1. FIG. 2 is a conceptual diagram showing an ink pressure buffering mechanism in which the flexible member is formed of a flexible tube in the ink pressure buffering mechanism according to the present invention. FIG. 3 is a conceptual diagram showing an ink pressure buffering mechanism in which the flexible member is formed of a flexible film film in the ink pressure buffering mechanism according to the present invention. 2 and 3, 11 is a flexible member of the ink pressure buffering mechanism, 12 is a space portion installed so as to cover the flexible member, 13 is a liquid filled in the space portion 12, and 14 is a space portion. 12, a valve for switching the space 12 to outside air communication / sealing is shown.

  In the ink discharge apparatus shown in FIG. 1, the case where the ink discharge head 1 is stopped at a predetermined position, the print medium 20 is moved, and the print pattern 21 is drawn is illustrated. However, in the ink discharge apparatus shown in FIG. Ink discharge heads such as movement of the ink discharge head 1 from a head maintenance position (not shown), movement of the ink discharge head 1 from a standby position during non-printing, and movement of the ink discharge head 1 in the print medium effective width direction 1 is moved in the direction of the arrow in the figure. Then, a pressure change occurs with respect to the ink inside the ink discharge head 1 and the ink supply pipe 3 connected to the head due to acceleration / deceleration and vibration accompanying the movement of the ink discharge head 1, and the nozzle hole portion of the ink discharge head 1. In this case, the normal meniscus cannot be maintained, and the ink ejected from the ink ejection head 1 is bent (misdirection), the ejection failure due to air mixing into the nozzle hole, and the ink leakage from the nozzle hole. Will occur. In order to prevent this, the pressure change is suppressed by the ink pressure buffer mechanism 10.

  At this time, the ink pressure buffer mechanism shown in FIGS. 2 and 3 uses the deformation of the flexible member 11 to suppress the change in the pressure of the ink, but the space portion is installed so as to cover the flexible member 11. By setting the valve 14 installed in the open air to the open air state, the liquid 13 filled in the space 12 installed so as to cover the flexible member can be freely changed in volume, and the ink pressure The deformation of the flexible member 11 of the buffer mechanism is not hindered, and the change in the pressure of the ink is suppressed by the deformation of the flexible member 11.

  On the other hand, during printing of the print pattern 21 on the print medium 20, meniscus control of the nozzle holes of the ink discharge head 1 is performed by the ink supply mechanism 2 shown in FIG. 1, and at this time, as shown in FIGS. When the flexible member 11 of the ink pressure buffering mechanism is deformed, a change in pressure is excessively suppressed due to the effect, so that fine adjustment of the ink pressure for meniscus control by the ink supply mechanism 2 is absorbed, and meniscus control is performed. This hinders quality defects such as density unevenness.

  Therefore, in the ink pressure buffering mechanism shown in FIGS. 2 and 3, the flexible member 11 is closed by closing the valve 14 of the space 12 installed so as to cover the flexible member 11 and sealing the space. The liquid 13 filled in the space portion 12 installed so as to cover the volume becomes difficult to change in volume, and the deformation of the flexible member 11 of the ink pressure buffering mechanism is prevented, so that the ink supply shown in FIG. The mechanism 2 does not hinder fine adjustment of the ink pressure accompanying the meniscus control of the nozzle holes of the ink discharge head 1.

  In the ink pressure buffering mechanism 10 shown in FIGS. 2 and 3, the valve 14 of the space 12 installed so as to cover the flexible member 11 is connected to the outside air such as a ball valve, a diaphragm valve, and a needle valve. It does not matter if it is possible to switch between communication / sealing.

  In addition, in the ink pressure buffer mechanism shown in FIGS. 2 and 3, selection of opening / closing of the valve 14 in the space 12 installed so as to cover the flexible member 11 is performed by manually operating a knob for opening / closing the ball valve, for example. However, the diaphragm valve may be an air operated type and may be manually operated depending on whether air is supplied or not. For example, an air operated type diaphragm valve is used, and the ink ejection head 1 shown in FIG. The valve operation is performed so that the movement state is monitored, and when the ink discharge head 1 is in the movement state and the ink pressure fluctuates, opening is selected, and when the ink discharge head 1 is in the printing state, sealing is selected. It is preferable to automatically control the air supply switching for switching and to select opening and closing.

  In the ink pressure buffering mechanism shown in FIGS. 2 and 3, the liquid 13 filled in the space 12 installed so as to cover the flexible member 11 is preferably a non-volatile liquid. That is, even when the valve 14 of the space portion 12 installed so as to cover the flexible member 11 is in an open air state, the liquid 13 does not evaporate to the outside air, so the replenishment and maintenance frequency of the liquid 13 is reduced. It is possible to make it.

  In the ink ejection device and the ink pressure buffering method of the present invention, the colored ink for forming the pixel of the color filter, the droplet for forming the light emitting layer of the EL display, and the metal for forming the antenna of the IC tag. It is possible to discharge contained droplets. That is, examples of the recording medium include color filters, organic electroluminescence elements, wiring circuits, and the like used in liquid crystal display devices.

Next, the present invention will be specifically described by way of examples. Pattern printing was performed using the ink ejection apparatus shown in FIG. A mixture of 15 wt% pigment, 15 wt% resin, and 70 wt% alcohol solvent was used as the ink, and a piezoelectric element type ink discharge head was used as the ink discharge head. Paper was used as a printing medium, and an ink supply mechanism constituted by a diaphragm pump was used as an ink supply mechanism for meniscus control. The ink pressure buffer mechanism shown in FIG. 2 was installed in the middle of the ink supply pipe. A fluorine-based flexible tube was used as the flexible member of the ink pressure buffering mechanism, and the space portion installed so as to cover the flexible member was filled with silicon-based oil. An air operated type diaphragm valve was used for the valve in the space portion so as to cover the flexible member, and the opening / closing of the valve was selected by automatic control for monitoring the moving state of the ink discharge head.

  A pattern that moves the ink ejection head from the standby position to the maintenance position, performs maintenance of the ink ejection head, then moves the ink ejection head from the maintenance position to the printing position, and ejects ink from all nozzle holes of the ink ejection head Was printed on paper, and after the completion of printing, the operation until the ink ejection head was moved to the standby position was taken as one operation, and pattern printing was repeated 100 times. Although the print pattern was confirmed for each operation, no misdirection, ejection failure, or density unevenness was confirmed.

  The ink pressure buffer mechanism shown in FIG. 3 was installed in the middle of the ink supply pipe, and printing was performed in the same manner as in Example 1 except that a resin film was used as the flexible member of the ink pressure buffer mechanism. Misdirection, ejection failure, and density unevenness were not confirmed in the print pattern for each operation.

(Comparative example)
When printing was performed in the same manner as in Example 1 except that the valve of the space portion installed so as to cover the flexible member of the ink pressure buffering mechanism was always opened and the ink pressure buffering mechanism was always enabled, In the printing pattern for each operation, no misdirection or ejection failure was confirmed, but density unevenness occurred.

It is a conceptual diagram which shows embodiment of the ink discharge apparatus by this invention. In the ink pressure buffer mechanism according to the present invention, it is a conceptual diagram showing an ink pressure buffer mechanism in which a flexible member is constituted by a flexible tube. In the ink pressure buffering mechanism according to the present invention, the ink pressure buffering mechanism in which the flexible member is formed of a flexible film is a conceptual diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ink discharge head 2 ... Ink supply mechanism 3 ... Ink supply piping 10 ... Ink pressure buffer mechanism 11 ... Flexible member 12 of an ink pressure buffer mechanism ... Flexible member The space 13 installed so as to cover the liquid ... The liquid 14 filled in the space ... The valve 20 installed in the space ... The print medium 21 ... the printing pattern

Claims (6)

An ink discharge head; an ink supply mechanism for supplying ink to the ink discharge head at a constant pressure; an ink supply pipe connecting the ink discharge head and the ink supply mechanism; In an ink ejection device provided with an ink pressure buffering mechanism for suppressing
The ink pressure buffering mechanism includes a flexible member for suppressing ink pressure fluctuation and a space portion installed so as to cover the flexible member, and for switching communication / sealing with outside air in the space portion. An ink ejection device characterized by comprising a valve.   The ink ejection apparatus according to claim 1, wherein the flexible member of the ink pressure buffering mechanism includes a flexible tube.   2. The ink ejection device according to claim 1, wherein the flexible member of the ink pressure buffering mechanism is made of a flexible film film.   The ink ejection device according to claim 1, wherein a space portion installed so as to cover the flexible member of the ink pressure buffering mechanism is filled with a liquid.   The ink ejection apparatus according to claim 4, wherein the liquid filled in the space provided so as to cover the flexible member of the ink pressure buffering mechanism is a non-volatile liquid.   By using the ink ejection device according to any one of claims 1 to 5, an ink pressure is provided by opening and closing a valve provided in a space portion of the ink pressure buffer mechanism that is installed so as to cover a flexible member. An ink pressure buffering method, wherein the effect of suppressing fluctuation is switched between valid and invalid.