JP6441729B2 - Ink jet recording apparatus and ink viscosity control method used therefor - Google Patents

Description

  The present invention relates to an ink jet recording apparatus, and more particularly to a method for controlling ink viscosity.

  As a background art in this technical field, there is JP 2014-34142 A (Patent Document 1). In the so-called continuous type inkjet recording apparatus described in Patent Document 1, ink is ejected from a nozzle, only ink particles used for printing are charged by a charging electrode, and the charged ink particles are deflected by a deflection electrode. Printing is performed by deflecting the flying direction, and ink particles that are not used for printing are sucked and collected by the gutter and used again for printing. In the gutter, when the ink particles are sucked and collected, the surrounding air is sucked at the same time. Since the sucked air continues to be sent into the ink container, it is discharged from the ink container to the outside of the apparatus, or the flow path is switched by an electromagnetic valve and supplied to the gas-liquid separator in the print head. Yes.

  Moreover, there exists Unexamined-Japanese-Patent No. 2004-66499 (patent document 2). In the ink jet recording apparatus described in Patent Document 2, when the environmental temperature changes, the concentration of ink used for printing is changed, and the ink ejected from the nozzles becomes finer and the ink viscosity is within a printable range. It is configured to control.

JP 2014-34142 A JP 2004-66499 A

  For example, in the so-called continuous ink jet recording apparatus described in Patent Document 1 and Patent Document 2, when the ink ejection is stopped, the solvent is ejected from the nozzle, the nozzle and the ink recovery path are washed, and the operation is stopped. Is used.

  Depending on the customer, the operation frequency of the ink jet recording apparatus is low, and the ink is diluted with the solvent by repeating the short-time operation and the cleaning stop, and the ink viscosity may be lowered.

  In such a case, the ink viscosity range that can be printed is out of the range, which may lead to troubles such as printing disturbance. For this reason, it is necessary to concentrate the ink as soon as possible to return it to a printable ink viscosity value. From this viewpoint, Patent Document 1 and Patent Document 2 are not considered.

  An object of the present invention is to prevent troubles such as printing disturbance by performing control to return to a viscosity value that can be printed as soon as possible when the ink viscosity value is out of a printable ink viscosity range. It is to provide an ink jet recording apparatus.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-mentioned problems. To give an example, a main ink container that stores ink stored in the apparatus main body, and ink as ink particles are ejected to a printed material. A nozzle that performs printing, an ink supply channel that supplies ink from the ink container to the nozzle, a gutter that collects ink particles that are not used for printing among the ink particles discharged from the nozzle, and ink particles that are collected by the gutter An ink collecting channel for collecting the solvent gas in the ink container, a solvent gas discharging channel connected to the ink container for discharging the solvent gas from the main ink container, and a solvent gas agglomerated liquid due to a temperature drop in the solvent gas discharging channel. An ink jet recording apparatus comprising a gas-liquid separator for gas-liquid separation, wherein air sucked from the gas-liquid separator is supplied to a main ink container, and a solvent in the main ink container A configuration to concentrate the ink by discharging the scan.

  According to the present invention, when the ink viscosity value is out of the printable ink viscosity range, it is possible to prevent troubles such as printing disturbance by performing the control to return to the printable viscosity value as soon as possible. An ink jet recording apparatus can be provided.

1 is a perspective view of a main body and a print head of an ink jet recording apparatus according to the present invention. FIG. 5 is a perspective view showing the basic operation of the ink jet recording apparatus according to the present invention. It is a perspective view which shows the use condition of the inkjet recording device which concerns on this invention. 1 is a perspective view showing an appearance of a print head of an ink jet recording apparatus according to the present invention. 1 is a path configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. It is a longitudinal cross-sectional view of the main ink container in the Example of this invention. 1 is a functional block diagram of an ink jet recording apparatus according to an embodiment of the present invention. It is an ink viscosity control flow in the Example of this invention. FIG. 5 is a fluid path diagram showing the flow of ink, air, and solvent when a normal printing operation is performed in the embodiment of the present invention. FIG. 4 is a fluid path diagram showing the flow of ink, air, and solvent when a printing operation is performed in the embodiment of the present invention and solvent gas is discharged out of the apparatus. FIG. 4 is a fluid path diagram showing the flow of ink, air, and solvent when a printing operation is performed in the embodiment of the present invention and air is sucked from the gas-liquid separator. It is a figure which shows the solvent consumption in each operating condition in the Example of this invention. It is a figure which shows the solvent consumption at each temperature in the Example of this invention.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. In addition, this invention is not limited to a following example.

  First, the external configuration of the apparatus will be described. FIG. 1 is a perspective view showing an ink jet recording apparatus 500. The ink jet recording apparatus 500 includes a main body 1 provided with an operation display unit 3 and a print head 2 outside. The main body 1 and the print head 2 are connected by a conduit 4.

  Next, the operation principle of the ink jet recording apparatus 500 will be described with reference to FIG. In FIG. 2, the ink 7 </ b> A in the ink container 18 is sucked and pressurized by the pump 25 to become an ink column 7 </ b> B and is ejected from the nozzle 8. The nozzle 8 is provided with an electrostrictive element 9, and the ink column 7B ejected from the nozzle 8 is made into particles by applying vibration to the ink at a predetermined frequency. The number of ink particles 7C thus generated is determined by the frequency of the excitation voltage applied to the electrostrictive element 9, and is the same as the frequency. The ink particles 7 </ b> C can be charged by applying a voltage having a magnitude corresponding to the print information at the charging electrode 11.

  The ink particles 7C charged by the charging electrode 11 are deflected by receiving a force proportional to the charge amount while flying in the electric field between the deflection electrodes 12, and fly toward the print target 13 and land. To do. At that time, the landing position of the ink particle 7C changes in the deflection direction according to the charge amount, and the production line 13 moves the print target 13 in the direction orthogonal to the deflection direction, so that the ink particle 7C also moves in the direction orthogonal to the deflection direction. Particles can be landed, and a character is composed of a plurality of landed particles for printing.

The ink particles 7C that have not been used for printing fly linearly between the deflection electrodes 12 and are collected by the main ink container 18 via a path after being captured by the gutter 14.
Next, an example of an actual use state of the ink jet recording apparatus 500 is shown in FIG. For example, the ink jet recording apparatus 500 is installed on a production line in a factory where food and beverages are produced, the main body 1 is installed at a position where the user can operate, and the print head 2 is on a production line such as a belt conveyor 15. Is placed at a position where it can come close to the printing object 13 to be fed.

  In order to print on the production line such as the belt conveyor 15 with the same width regardless of the feeding speed, the encoder 16 that outputs a signal corresponding to the feeding speed to the ink jet recording apparatus 500 and the printing object 13 are detected. A print sensor 17 that outputs a signal for instructing printing to the inkjet recording apparatus 500 is installed, and each is connected to a control unit (not shown) in the main body 1.

  In accordance with signals from the encoder 16 and the print sensor 17, the control unit controls the charge amount and charging timing of the ink particles 7 </ b> C ejected from the nozzle 8, and charges while the print target 13 passes near the print head 2. The deflected ink particles 7C are attached to the print object 13 for printing.

  Next, the configuration of the print head 2 will be described with reference to FIG. FIG. 4 shows a state in which the print head cover 52 is attached to the print head 2. Inside the print head 2 are a nozzle 8 for ejecting ink particles, a charging electrode 11 for charging ink particles to be printed, a deflection electrode 12 for deflecting ink particles, and a gutter 14 for collecting non-printing ink particles. It is arranged on the line. Further, a gas-liquid separator 53 is installed beside the nozzle 8 (not shown). 52A is an opening through which ink particles to be printed protrude. The gas-liquid separator will be described in detail later.

  FIG. 5 is an explanatory diagram showing an overall path configuration of the inkjet recording apparatus 500. First, the ink supply path of the ink jet recording apparatus 500 of this embodiment will be described. In FIG. 5, the main body 1 is provided with a main ink container 18 for holding the circulating ink 7A. The main ink container 18 is connected to an electromagnetic valve 22A that opens and closes a path via a path 201, and the electromagnetic valve 22A is connected to a merging path 291 via a path 202. The merging path 291 is connected to a pump (for supply) 24 used for sucking and pressure-feeding the ink 7A via the path 203. The pump (for supply) 24 is connected via a path 204 to a filter (for supply) 28 that removes foreign matters mixed in the ink 7A.

  The filter 28 is connected to a pressure reducing valve 33 that adjusts the pressure to an appropriate pressure for printing the ink 7A pumped from the pump (for supply) 24 via the path 205, and the pressure reducing valve 33 is connected via the path 206. A pressure gauge 31 for measuring the pressure of the ink 7A supplied to the nozzle is provided.

The pressure gauge 31 is provided in the print head 2 via a path 207 passing through the conduit 4 and is connected to a nozzle 8 having an ejection port for ejecting ink 7A.
A gutter 14 for capturing ink particles 7C that fly straight without being charged or deflected because it is not used for printing is disposed in the straight direction of the nozzle 8 outlet.
Next, the ink recovery path of the ink jet recording apparatus 500 of this embodiment will be described. The gutter 14 is connected to a filter (for recovery) 30 that removes foreign matters mixed in the ink disposed in the main body 1 via a path 211 passing through the conduit 4. 30 is connected to a solenoid valve 22B that opens and closes the path via a path 212. The electromagnetic valve 22B is connected to a pump (for recovery) 25 that sucks the ink particles 7C captured by the gutter 14 via a path 213.

  The pump (for recovery) 25 is connected to the merging path 292 via the path 214, and the merging path 292 is connected to the main ink container 18 via the path 215.

  Next, the ink supply path of the ink jet recording apparatus 500 of this embodiment will be described. The main body 1 is provided with an auxiliary ink container 19 that holds ink for replenishment. The auxiliary ink container 19 is connected to an electromagnetic valve 22 </ b> C that opens and closes the path via the path 221. The electromagnetic valve 22C is connected to the merging path 291 through the path 222.

  Next, the ink circulation path of the ink jet recording apparatus 500 of this embodiment will be described. The nozzle 8 provided in the print head 2 is provided in the main body 1 through a path 225 passing through the conduit 4 in addition to the ink supply path 207 and is connected to an electromagnetic valve 22D that opens and closes the flow path. Has been.

  The electromagnetic valve 22 </ b> D is connected to a pump (for circulation) 26 that sucks ink from the nozzles 8 through a path 226, and the pump (for circulation) 26 is connected to a merging path 292 through a path 227. It has become.

  Next, the viscosity measurement path of the ink jet recording apparatus 500 of this embodiment will be described. In order to grasp the viscosity of the ink 7A in the main ink container 18, a viscosity measuring device 21 is provided. A flow path on the primary side of the viscosity measuring device 21 is connected to a filter (for viscosity measurement) 34 that removes foreign matters mixed in the ink 7 </ b> A via a path 232, and the filter (for viscosity measurement) 34. Is connected to the main ink container 18 via a path 231.

  The flow path on the secondary side of the viscosity measuring device 21 is connected to the electromagnetic valve 22E for opening and closing the flow path via the path 233, and the electromagnetic valve 22E joins the path 226 via the path 234. Connected to the merging path 293.

  Next, the solvent supply path of the ink jet recording apparatus 500 of this embodiment will be described. The main body 1 is provided with a solvent container 20 for holding a solvent for solvent replenishment. The solvent container 20 is connected to a pump (for solvent) 27 used for sucking and pumping the solvent through a path 236. It is connected. The pump (for solvent) 27 is connected to the electromagnetic valve 22F for opening and closing the flow path via the path 237, and the electromagnetic valve 22F is connected to the main ink container 18 via the path 238.

  Next, the exhaust path and the solvent gas circulation path of the present embodiment will be described. The main ink container 18 is connected to the electromagnetic valve 22H to open and close the flow path via the path 246, and the electromagnetic valve 22H is installed in the print head 2 via the path 248 passing through the conduit 4. The gas-liquid separator 53 is connected.

  The liquid outlet pipe of the gas-liquid separator 53 is installed in the main body 1 via a path 250 passing through the conduit 4 and is connected to an electromagnetic valve 22J for opening and closing the flow path. It is connected to a merge path 294 that merges with the path 226 via a path 244.

  Next, the main ink container of this embodiment will be described. FIG. 6 shows a cross-sectional view of the main ink container 18 according to one embodiment of the present invention. In FIG. 6, the main ink container 18 includes a liquid reservoir 61 that holds the ink 7 </ b> A, and a container lid 62 that serves as a lid for sealing the liquid reservoir 61. The container lid 62 is connected to the path 201 and the tip is immersed in the ink 7 </ b> A held in the liquid storage unit 61. The container lid 62 is connected to the path 246 and the tip is above the electrode (for overflow sensor) not shown. , An exhaust pipe 64, a recovery pipe 65 connected to the ink recovery path 215, and a solvent supply pipe 66 connected to the solvent supply path 238.

  Further, the container lid 62 has an electrode (GND) 67 immersed in the ink 7A held at the tip in the liquid storage section 61, a level 2 electrode 69 arranged at 77B whose tip indicates the liquid level B, A level 3 electrode 70 disposed at 77C indicating the liquid level C with the tip disposed below the liquid level B, and a level 3 electrode 70 disposed above 77B indicating the liquid level B with the tip disposed at the liquid level A And a level 1 electrode 68 arranged at 77A. With such a configuration, the electrodes 67, 68, 69, 70 detect whether or not the liquid in the main ink container 18 has reached a reference liquid level that is an appropriate amount to be held inside. Although functioning as a surface sensor, although not shown, for example, a galvanometer or the like can be used to select two wires connected to the electrodes and connect them to the galvanometer, and the conduction state can be observed depending on the presence or absence of current. That is, the presence or absence of ink between the electrodes can be checked.

  Next, the control system of the present embodiment will be described. FIG. 7 shows a functional block diagram of the ink jet recording apparatus 500. The ink jet recording apparatus 500 includes a control unit 300 including, for example, an MPU. The control unit 300 is configured to operate the operation display unit 3, the nozzle 8, the charging electrode 11, the deflection electrode 12, the encoder 16, via the bus line 301. The print sensor 17, the viscosity measuring device 21, the electromagnetic valves 22A to 22K, the pumps 24 to 27, the pressure reducing valve 30, the liquid level sensors 67, 68, 69, 70, the recording unit 302, and the like are controlled.

  The recording unit 302 stores a program for controlling the ink jet recording apparatus 500, and the control unit 300 controls each part of the ink jet recording apparatus 500 based on this program.

  The recording unit 302 records an appropriate ink viscosity of ink for printing, that is, an upper limit value (η max) and a lower eye value (η min) for printing.

  In an ink jet recording apparatus, it is necessary to control the viscosity of the ink discharged from the nozzle within a range where printing can be properly performed. When the ink viscosity is out of the proper range, the ink discharged from the nozzle is converted into particles. As a result, a phenomenon such as a change in the position of the ink particles or a phenomenon that the ink particles are not formed into a uniform shape occurs, a desired charge amount cannot be given to the ink particles, and an appropriate printing result cannot be obtained.

  Therefore, in order to avoid the occurrence of the above phenomenon, the ink jet recording apparatus needs a means for adjusting the ink viscosity and maintaining the ink viscosity within a predetermined range.

  In the ink jet recording apparatus 500 of the present embodiment, when the ink concentration is diluted with a solvent, it takes time to return the ink concentration to a normal value because the amount of solvent consumption is small during normal operation. Therefore, when the viscosity of the ink is less than the specified value when the ink viscosity is measured, control is performed to temporarily increase the solvent consumption and return the ink density to a normal value (ink viscosity increase control).

  In addition, the ink jet recording apparatus includes a temperature sensor in the main body 1 and determines the ink viscosity increase control method based on the measured value. Next, the operation of the ink jet recording apparatus 500 according to this embodiment will be described.

  FIG. 9 shows an ink flow and an air flow when a printing operation is performed, that is, when ink is ejected from the nozzle 8 (hereinafter referred to as operating condition A) in the ink jet recording apparatus 500 according to the present embodiment. Is a fluid path diagram indicated by a bold line. In FIG. 9, during the driving operation in which the printing operation is performed, the electromagnetic valve 22 </ b> A is energized to open the flow path, and the ink 7 </ b> A stored in the main ink container 18 as shown by the ink supply flow path 401. Is supplied to the nozzle 8 by operating the pump (for supply) 24. Here, the ink flow rate of the ink supply channel 401 is about 3.5 [ml / ml, for example, when the hole diameter of the nozzle 8 is 65 [μm] and the ink supply pressure to the nozzle 8 is 0.250 [MPa]. Min].

  Further, in the ink recovery path, the electromagnetic valve 22B is energized to open the flow path, and as shown in the ink recovery flow path 402, the ink particles 7C that have not been used for printing operate the pump (for recovery) 25. As a result, the ink is recovered from the gutter 14 to the main ink container 18 and the ink is circulated in the apparatus. Here, in the ink recovery flow path 402, the ink particles 7C ejected from the nozzle 8 (about 3.5 [ml / min]) and the ink particles used for printing (assuming 0.5 [ml / min]). In this case, ink having a difference of about 3.0 [ml / min] (= 3.5−0.5) is collected from the gutter 14. In the ink recovery flow path 402, air sucked together with ink from the gutter 14 flows. This is because the path 211 for connecting the gutter 14 in the print head 2 and the pump (for recovery) 25 in the main body 1 is about 4 [m], and when trying to suck only ink, the load becomes large and suction cannot be performed. This is because the ink overflows from the gutter 14. Therefore, when ink is sucked from the gutter 14, air is sucked by about 150 [ml / min]. That is, the ink recovery flow path 402 flows in a gas-liquid mixed state in which ink (for example, about 3.0 [ml / min]) and air (for example, about 150 [ml / min]) are mixed.

  The ink 7A used in the ink jet recording apparatus 500 is required to be dried immediately after printing, and a highly volatile solvent (for example, methyl ethyl ketone, acetone, ethanol, etc.) is used as the solvent of the ink 7A. Is done. Since a highly volatile solvent is used for the ink 7A, solvent vapor close to the saturated vapor concentration is dissolved in the air flowing through the ink recovery flow path 402. Further, the solvent vapor is dissolved in the air by the temperature of the main ink container 18 due to the temperature rise of the main body 1.

  Next, the solvent gas circulation channel 403, the liquid recovery channel 405, and the solvent gas supply channel 404 will be described with reference to FIG.

  In the liquid recovery path 250, the solenoid valve 22J is energized to open the flow path, and the liquid flowing into the gas-liquid separator 53 operates the pump (for circulation) 26 as shown in the liquid recovery flow path 405. Is collected in the main ink container 18. Here, in the liquid recovery flow path 405, the liquid and saturated solvent vapor flow in a gas-liquid mixed state. The liquid is, for example, about 5 [ml / hour] (environmental temperature 20 [° C.]), and the solvent vapor is about The flow rate is 150 [ml / min].

  The main ink container 18 is configured to receive and hold the ink flowing through the ink recovery flow path 402 and the liquid flowing through the liquid recovery flow path 405. Further, the solvent vapor (about 150 [ml / min]) flowing through the ink recovery flow path 402 and the solvent vapor (about 150 [ml / min]) flowing through the liquid recovery flow path 405 are combined with about 300 [ml. / Min] (= 150 + 150), after flowing into the main ink container 18, the solenoid valve 22 </ b> H is energized to open the flow path, so that the air passes through the path 248 as shown by the solvent gas circulation flow path 403. It flows into the liquid separator 53. The solvent vapor of about 300 [ml / min] is partially liquefied due to the temperature difference between the main ink container 18 and the gas-liquid separator 53 (for example, about 5 [ml / hour] (environmental temperature 20 [° C.]). And the gas-liquid separator 53. In the gas-liquid separator 53, since the liquid can be sucked from the liquid recovery path 250, gas (solvent gas, flow rate of about 150 [ml / min]) is discharged into the print head 2 through the path 249. This is shown in the figure as a solvent gas supply channel 404.

  As a result, since the solvent gas having a high saturated vapor concentration can be sucked from the gutter 14 in the print head 2, even if the ink and air flow in a gas-liquid mixed state in the ink recovery flow path 402, Volatilization of the solvent component in the ink can be reduced. Further, the gas-liquid separator 53 prevents the liquid from flowing into the print head 2.

  Next, FIG. 10 shows the case where the viscosity is measured and the solvent gas is discharged to the outside of the apparatus (hereinafter referred to as operating condition B) in the ink jet recording apparatus 500 according to the present embodiment. FIG. 6 is a fluid path diagram showing the ink flow, air flow, and solvent flow in FIG. The ink supply channel 401 and the ink recovery channel 402 are the same as in FIG.

  In the exhaust path, the solenoid valve 22K is energized to open the flow path, and the solvent gas (about 150 [ml / min]) that flows from the ink recovery flow path 402 into the main ink container 18 flows into the solvent gas discharge flow path 406. As shown in FIG. 2, the gas is discharged into the exhaust duct 50 and further discharged outside the apparatus.

  Further, when the viscosity is measured, the electromagnetic valve 22E is energized to open the flow path, and the ink 7A stored in the main ink container 18 operates the pump (for circulation) 26 as shown by the ink flow path 407 at the time of viscosity measurement. By doing so, it is supplied to the viscosity measuring device 21. By operating in this way, the pump (for circulation) 26 is selectively used for the liquid recovery channel 405 and the viscosity measurement ink channel 407.

  Further, the ink concentration in the main ink container 18 is increased by the amount of the solvent in the ink volatilized in the ink recovery channel 402. Therefore, the concentration of ink supplied to the nozzle 8 is adjusted by periodically replenishing the main ink container 18 with the solvent. During the solvent supply, the solenoid valve 22F is energized to open the flow path, and the solvent stored in the solvent container 20 is supplied to the main ink container 18 by operating the pump (for solvent) 27.

  Next, FIG. 11 shows the case where air is sucked from the gas-liquid separator 53 and supplied to the main ink container 18 in the ink jet recording apparatus 500 according to this embodiment, and the solvent gas is discharged outside the apparatus ( FIG. 5 is a fluid path diagram showing the ink flow, the air flow, and the solvent flow in thick lines in the operation condition C). The ink supply channel 401 and the ink recovery channel 402 are the same as in FIG.

  In the liquid recovery path, the solenoid valve 22J is energized to open the flow path, and as shown in the air suction flow path 408, the pump (for circulation) 26 is operated to suck air from the gas-liquid separator 53. To the main ink container 18. The flow rate of the air suction channel 408 is determined by the capacity of the pump (for circulation) 26.

  In the main ink container 18, a solvent in which the solvent vapor (about 150 [ml / min]) flowing through the ink recovery channel 402 and the solvent vapor (about 150 [ml / min]) flowing through the air suction channel 408 are combined. About 300 [ml / min] of vapor (= 150 + 150) flows into the main ink container 18, and then the solenoid valve 22K is energized to open the flow path, so that the solvent gas discharge flow path 406 is shown. It flows into the exhaust duct 50 through the path 257 and is discharged out of the machine.

  FIG. 12 is a diagram comparing solvent consumption under the above-described operating conditions. That is, in FIG. 12, the operating condition A is the state shown in FIG. 9 when the printing operation is performed, that is, when the ink is ejected from the nozzle 8, and the operating condition for suppressing the volatilization of the solvent. Therefore, for example, the solvent consumption is as small as 2.5 ml / hour.

  The operating condition B is the state shown in FIG. 10 when the viscosity measurement is being performed and when the solvent gas is being discharged to the outside of the machine. The ink recovery flow path 402 is the same as the operating condition A in FIG. 9, but only because there is no effect of reducing the volatilization of the solvent component by the gas-liquid separator and because the solvent gas is discharged outside the apparatus. The solvent consumption is increased, for example, the solvent consumption is 5 ml / hour.

  The operating condition C is the state shown in FIG. 11 when air is sucked from the gas-liquid separator 53 and supplied to the main ink container 18 and the solvent gas is discharged to the outside of the machine. The flow path 401 and the ink recovery flow path 402 are the same as the operating condition A in FIG. 9, but the solvent vapor flowing through the ink recovery flow path 402 and the solvent vapor flowing through the air suction flow path 408 are combined. After the solvent vapor flows into the main ink container 18, the solvent consumption increases by the amount discharged from the exhaust circulation pipe 64 to the outside of the machine through the solvent gas discharge flow path 409. For example, the solvent consumption becomes 10 ml / hour. .

  The operating conditions D and E are the same as the ink and air flows in FIG. 11 of the operating condition C, but the flow rate of the pump is changed. The pumps 24 to 27 employed in this embodiment are diaphragm pumps. For example, the pump flow rate can be changed by changing the pump frequency to 2 Hz in the operation condition C, 3 Hz in the operation condition D, and 4 Hz in the operation condition E. Can be controlled. Therefore, since the air flow rate increases as the operating conditions D and E increase, the solvent consumption increases accordingly. For example, the solvent consumption becomes 15 ml / hour under the operating condition D and 20 ml / hour under the operating condition E. Thus, solvent consumption can be controlled by changing operating conditions.

  FIG. 13 is a diagram comparing solvent consumption by temperature under operating conditions A and C. In FIG. 13, the solvent consumption under the operating condition C is shown on the left axis, and the solvent consumption under the operating condition A is shown on the right axis. As shown in FIG. 13, the higher the environmental temperature, the larger the solvent consumption. In particular, by controlling under the operating condition C, it is possible to increase the solvent consumption and concentrate the ink quickly. Therefore, when it is desired to increase the viscosity quickly according to the state of the ink viscosity, it can be promoted by switching to the operating condition C and further increasing the temperature. In addition, it is possible to switch between the operating condition A in which the consumption amount of the solvent is increased and the operating condition C in which the consumption amount of the solvent is increased in order to increase the ink viscosity.

  Next, ink viscosity control in this embodiment will be described with reference to FIG. FIG. 8 is a control flow showing the viscosity increase control method when the ink viscosity is measured and the ink viscosity value is lower than a certain value, and the viscosity reduction control method when the ink viscosity value is higher than the certain value. FIG.

  First, step S801 shows a state in which the ink 7C that has been atomized from the nozzle 8 under the operating condition A is ejected, and the ink particles 7C are being collected from the gutter 14. Step S801 is operating under the operating condition A (FIG. 9), and the main ink container 18 is controlled at the position of the liquid level B. For example, the ink viscosity value is controlled to be in the range of the standard value η = 100 ± 7 [%].

  Step S802 indicates that ink viscosity measurement is performed. In step S803, it is determined whether “viscosity value ≧ ηmin”. For example, the ink viscosity value ηmin = 75 (75% of the standard value). If the ink viscosity value is equal to or greater than ηmin, “Yes” is determined, and the process proceeds to step S804. If the ink viscosity value is smaller than ηmin, “No” is determined, and the process proceeds to step S811.

  In step S811, since it is determined that the ink viscosity is low, the ink can be concentrated earlier than in the normal operation (operation condition A) by operating the operation conditions B to E. In this step, the main ink container 18 is concentrated from the liquid level B to the liquid level C. For example, when the ink viscosity value is 75 at the liquid level B and the ink is concentrated to the liquid level C, the ink viscosity value becomes 100.

  Step S812 indicates that ink viscosity measurement is performed. In step S813, it is determined whether “viscosity value ≧ ηmin”. If the ink viscosity value is equal to or greater than ηmin, “Yes” is determined, and the process proceeds to step S814. If the ink viscosity value is smaller than ηmin, “No” is determined, and the process proceeds to step S815.

  Step S815 indicates that the alarm “low viscosity” is generated in order to call the customer's attention because the viscosity does not fall within the printable ink viscosity range even when the viscosity increase control is performed. For example, when the ink viscosity in step S812 is extremely low, such as 50, the standard viscosity value of 100 is not obtained by one-time ink concentration control. Therefore, the process returns again to step S811, and the ink concentration control is performed again.

Step S814 indicates that ink is supplied from the auxiliary ink container 19 to the main ink container 18 from the liquid level C to the liquid level B. If completed, the process proceeds to step S805 to return to the control during ink ejection at the normal liquid level B.
This step S805 is the same operation control as step S801. In step S804, it is determined whether “viscosity value ≦ ηmax”. For example, the ink viscosity value ηmax = 125 (125% of the standard value). If the ink viscosity value is equal to or less than ηmax, “Yes” is determined, and the process proceeds to step S805. If the ink viscosity value is larger than ηmax, “No” is determined, and the process proceeds to step S821.

  In step S821, since it is determined that the ink viscosity is high, the solvent is supplied from the solvent container 20 to the main ink container 18 from the liquid level B to the liquid level A of the main ink container 18. For example, when the ink viscosity value is 125 at the liquid level B, the ink viscosity value becomes 100 when the solvent is added to the liquid level A and diluted.

  Step S822 indicates that ink viscosity measurement is performed. In step S823, it is determined whether “viscosity value ≦ ηmax”. If the ink viscosity value is equal to or less than ηmax, “Yes” is determined, and the process proceeds to step S824. If the ink viscosity value is larger than ηmax, “No” is determined, and the process proceeds to step S825.

  Step S824 is operating under the condition of the operating condition A (FIG. 9), and the main ink container 18 is controlled at the position of the liquid level A.

  Step S825 indicates that the alarm “high viscosity” is generated to alert the customer because the viscosity does not fall within the printable ink viscosity range even when the viscosity reduction control is performed. For example, when the ink viscosity is extremely high in step S822, such as when the ink viscosity is 150, the standard viscosity value of 100 is not obtained in the ink dilution control. In such a case, further ink dilution is performed by discharging the ink from the main container 18 and replenishing the solvent. Then, the process proceeds to step S831.

  Step S831 indicates that the ink in the main container 18 is discharged from the liquid level A to the liquid level C. If completed, the process proceeds to step S832.

  Step S 832 indicates that the solvent is replenished from the liquid level C to the liquid level B in the main container 18. For example, in the case of an ink viscosity value of 125, if the solvent is added to the liquid level B and diluted, the ink viscosity value becomes 100. If completed, the process proceeds to step S833.

  Step S833 indicates that normal ink ejection is performed. If completed, the process proceeds to step S805. Step S805 indicates that ink ejection under the operating condition A is continued because it has been confirmed that the ink viscosity is within the printable ink viscosity range.

  As described above, in this embodiment, the main ink container that stores the ink stored in the apparatus main body, the nozzle that discharges the ink as ink particles and prints on the printing object, and the ink from the ink container to the nozzle. An ink supply channel that collects ink particles that are not used for printing, together with air, and an ink collection channel that collects ink particles collected by the gutter in an ink container; A solvent gas discharge passage connected to the ink container for discharging the solvent gas from the main ink container; and a gas-liquid separator for separating the liquid aggregate of the solvent gas due to temperature drop in the solvent gas discharge passage. An ink jet recording apparatus configured to concentrate ink by supplying air sucked from a gas-liquid separator to a main ink container and discharging a solvent gas in the main ink container

  Also, a method for controlling ink viscosity used in an ink jet recording apparatus that prints on an object to be printed by discharging ink as ink particles, the solvent gas discharging a solvent gas in a main ink container for storing ink In the discharge flow path, an operating condition A for suppressing the volatilization of the solvent by supplying air sucked from the gas-liquid separator for gas-liquid separation of the liquid aggregate of the solvent gas due to temperature drop to the main ink container; There are operating conditions B for discharging the solvent gas in the ink container, and operating conditions C for supplying air sucked from the gas-liquid separator to the main ink container and discharging the solvent gas in the main ink container. , B, and C are switched to control the ink viscosity.

  According to this embodiment, when the ink becomes thinner due to repeated washing stoppage, etc., and out of the printable ink viscosity range, the ink is concentrated faster than before by sucking air from the gas-liquid separator and concentrating the ink. Can be made. Therefore, it is possible to provide an ink jet recording apparatus that can prevent troubles such as printing disturbance due to changes in ink viscosity.

  The present invention is not limited to the above-described embodiments, and includes various modifications. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

DESCRIPTION OF SYMBOLS 1 ... Main-body part, 2 ... Print head part, 3 ... Operation display part, 4 ... Conduit, 7A ... Ink (in main ink container 18), 7B ... Ink column, 7C ... Ink particle, 8 ... Nozzle, 9 ... Electrostriction Element 11 ... Charging electrode 12 ... Deflecting electrode 13 ... Printing object 14 ... Gutter 15 ... Belt conveyor 16 ... Encoder 17 ... Print sensor 18 ... Main ink container 19 ... Auxiliary ink container 20 ... Solvent container, 21 ... viscosity measuring device, 22A-K ... solenoid valve, 24 ... pump (for supply), 25 ... pump (for recovery), 26 ... pump (for solvent), 27 ... pump (for circulation), 28 ... Filter (for supply), 30 ... Filter (for recovery), 31 ... Pressure gauge, 33 ... Pressure reducing valve, 34 ... Filter (for viscosity measuring device), 67, 68, 69, 70 ... Liquid level sensor, 39 ... Temperature sensor, 50 ... exhaust duct, 51 ... fan, 52 DESCRIPTION OF SYMBOLS ... Print head cover, 53 ... Gas-liquid separator, 61 ... Liquid storage part, 62 ... Container lid, 63 ... Suction pipe, 64 ... Exhaust circulation pipe, 65 ... Recovery pipe, 66 ... Solvent replenishment pipe, 67 ... Electrode (GND) , 68 ... Level 1 electrode, 69 ... Level 2 electrode, 70 ... Level 3 electrode, 77A ... Liquid level A, 77B ... Liquid level B, 77C ... Liquid level C, 201 to 207 ... Path (for ink supply) , 211 to 215... Path (for ink recovery), 221 to 222... Path (for ink supply), 225 to 227... Path (for circulation), 231 to 234... Path (for viscosity measurement), 236 to 238. Solvent replenishment), 241 to 244 ... path (for solvent gas circulation), 246 to 251 ... path (for solvent gas circulation), 256 to 257 ... path (for exhaust), 291 to 295 ... confluence path, 300 ... control unit DESCRIPTION OF SYMBOLS 301 ... Bus line, 302 ... Recording part, 401 ... Ink supply flow path, 402 ... Ink recovery flow path, 403 ... Solvent gas circulation flow path, 404 ... Solvent gas supply flow path, 405 ... Liquid recovery flow path, 406 ... Solvent Gas discharge channel, 407 ... viscosity measuring device ink circulation channel, 408 ... air suction channel, 500 ... inkjet recording apparatus

Claims (6)

A main ink container for storing ink stored in the apparatus main body;
A nozzle that discharges the ink as ink particles and prints on a substrate;
An ink supply channel for supplying the ink from the ink container to the nozzle;
Of the ink particles discharged from the nozzle, a gutter that collects the ink particles that are not used for printing together with air; and
An ink collection flow path for collecting the ink particles collected by the gutter in the ink container;
A solvent gas discharge passage connected to the ink container and discharging solvent gas from the main ink container;
An ink jet recording apparatus comprising a gas-liquid separator that gas-liquid separates a solvent gas aggregate due to a temperature drop in the solvent gas discharge flow path,
An ink jet recording apparatus, wherein the ink is concentrated by supplying air sucked from the gas-liquid separator to the main ink container and discharging a solvent gas in the main ink container. The inkjet recording apparatus according to claim 1,
The main ink container includes a first liquid level detection unit for detecting an ink liquid level and a second liquid level detection unit for detecting a liquid level below the first liquid level detection unit. ,
A viscosity measuring device for measuring the viscosity of the ink;
When the viscosity of the ink measured by the viscosity measuring device is equal to or lower than a predetermined value, the ink liquid level is concentrated until the position of the ink liquid level reaches the position of the second liquid level from the first liquid level detection unit. An inkjet recording apparatus. The inkjet recording apparatus according to claim 1,
The main ink container includes a first liquid level detection unit for detecting an ink liquid level and a third liquid level detection unit for detecting an upper liquid level of the first liquid level detection unit. ,
A viscosity measuring device for measuring the viscosity of the ink;
When the viscosity of the ink measured by the viscosity measuring device is equal to or greater than a certain value, the solvent is replenished until the position of the ink liquid level reaches the position of the third liquid level from the first liquid level detection unit. An ink jet recording apparatus. A method for controlling ink viscosity used in an ink jet recording apparatus that prints on an object to be printed by discharging ink as ink particles,
In the solvent gas discharge passage for discharging the solvent gas in the main ink container for storing ink, the air sucked from the gas-liquid separator for gas-liquid separation of the condensed liquid of the solvent gas due to the temperature drop is Operating condition A for suppressing the volatilization of the solvent by supplying it to the main ink container,
An operating condition B for discharging the solvent gas in the main ink container;
Operating conditions C for supplying air sucked from the gas-liquid separator to the main ink container and discharging the solvent gas in the main ink container;
An ink viscosity control method, wherein the ink viscosity is controlled by switching the operating conditions A, B, and C. The ink viscosity control method according to claim 4,
A method for controlling ink viscosity, wherein when the viscosity of the ink is not more than a certain value, the ink is operated under the operating condition C to increase the consumption of solvent and concentrate the ink. The ink viscosity control method according to claim 4,
An ink viscosity control method, wherein, when the ink viscosity is equal to or greater than a certain value, the operation is performed under the operation condition A to suppress the consumption of the solvent.

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