JP2015074183A - Inkjet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an inkjet recording device capable of high-speed printing with no printing distortion.SOLUTION: In a continuous discharge type inkjet device, by blowing an air stream along a flight direction of a droplet apart from a flight path of the droplet in a radial direction, an air flow is generated in a periphery of the droplet by attraction of the air stream (jet stream attraction effect), and a relative speed of the droplet to the peripheral air flow becomes slower and air resistance of the droplet is reduced, so that an inkjet recording device having small printing distortion is provided.

Description

The present invention relates to an ink jet recording apparatus.

  Among inkjet recording devices, the continuous ejection inkjet device is a highly stable droplet ejection device with higher reliability and higher maintenance than the on-demand inkjet device used in home or office printers. is there.

  For this reason, the continuous discharge type ink jet recording apparatus can be applied to manufacturing apparatuses such as electronic devices that require functional ink application and patterning using liquids that require high reliability, high maintenance, and high stability. It is. The apparatus can also be used as a three-dimensional model, for example, a 3D printer.

  In a continuous discharge type ink jet recording apparatus, a liquid (ink) stored in an ink tank is pressurized with a pump or the like and continuously ejected from a fine nozzle. The ink is vibrated by excitation by a piezoelectric element or the like, the ejected liquid is fluctuated, and the ejected ink column is cut, thereby causing the ink droplets to fly. At this time, the charging electrode is disposed close to the droplet forming position for cutting the ink column, and the formed droplet is charged by applying an electric field to the fine ink droplet.

  The charged droplet is controlled in the direction of flight in the electric field generated by applying a voltage to the deflection electrode placed downstream of the charging electrode, depending on whether or not it is charged and its size (charge amount). (Deflection process).

This deflection process is broadly classified into two systems, a multi-deflection type and a binary deflection type.
In any of these methods, since the amount of charge to the liquid (ink) after ejection is controlled and used for deflection of the liquid, it is not necessary to perform droplet ejection control for each droplet, and the configuration of the apparatus Becomes easy. In addition, since droplets are continuously discharged, nozzle clogging hardly occurs and high reliability can be ensured.

  However, in many of the continuous discharge type ink jet recording apparatuses, the distance between the flying droplets is narrow, so that the subsequent droplets merge with the front droplets or are separated (scattered) by the Coulomb repulsive force. As a result, an error (distortion) occurs in printing, and measures to insert uncharged dummy droplets between charged droplets for printing and charged droplets have been taken. there were.

A description will be given of how the droplet spacing is determined. In order to split the ejected liquid column (radius a) into droplets of the same diameter, it is optimal when there is a relationship such as k · a = 1 / (2) ^1/2 with the wave number k of vibration. It is theoretically known to split into From the relationship between this and the split ink column and the droplet volume, the relationship between the droplet interval L and the droplet diameter d is L = 2.36d. When the droplet d is determined, the droplet interval L is almost determined.

  Also, it is known that the air resistance (drag) of the following particles decreases to 60 to 80% when another particle flies within a distance of 6d behind the first flying particle (diameter d). Yes. Therefore, in the continuous discharge type ink jet recording apparatus, there has been a problem that distortion occurs in printing due to the subsequent droplets catching up with the leading droplets and coalescing or becoming discrete.

Therefore, conventionally, as disclosed in the following Patent Document 1, in the continuous discharge type inkjet recording apparatus, by adding the airflow in the direction in which the droplets fly by adding the airflow near the nozzle exit of the inkjet, Attempts have been made to reduce the air drag of the droplets.

Also, as disclosed in Patent Document 2 below, in a continuous discharge type ink jet recording apparatus, a passage is formed from an ink jet nozzle to a droplet outlet, and an air inlet is formed in the passage at right angles to the droplet flight direction. In order to prevent rebound from the recording medium, a discharge port was also provided.

In addition, as disclosed in Patent Document 3 below, in a continuous discharge type ink jet recording apparatus having a plurality of nozzles, the discharge port is divided into a main air stream that is caused to collide with the flight of liquid droplets and a peripheral sub air stream. Rectification was also performed.

JP-A-53-77626 JP 2011-161869 JP 2011-79274 JP

  However, in the additional airflow structure described in the above prior art, since the airflow directly collides with the droplet, the trajectory of the droplet is shifted due to the turbulence of the airflow, and printing at the correct position is not a problem. Although it has been devised such as adding a filter for disturbing the airflow before colliding with the droplet, it has been difficult to fundamentally reduce the disturbance generated by colliding with the droplet. Conventionally, there has been a problem that a printing error (distortion) occurs due to a short interval between ink droplets and interference between droplets.

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-described problems related to the additional airflow configuration in an ink jet device (or a continuous ink jet device), and provides an ink jet recording device for high speed printing without print distortion. And

In the present invention, in order to achieve the above-described object, a means for ejecting ink droplets, a means for generating a recording signal in accordance with recording information, a means for charging ink droplets based on the recording signal, and In a continuous discharge ink jet recording apparatus that records characters on a recording object that moves in a direction substantially perpendicular to the deflection direction.

By blowing away the air flow from the droplet flight path in the radial direction along the droplet flight direction, it is attracted to this air flow (jet air flow attracting effect), and an air flow is generated around the droplet. Ink jet recording apparatus in which the air drag of the liquid droplets and the relative velocity of the surrounding airflow are reduced to reduce the air drag of the droplets is provided.

Further, in the present invention, in the ink jet recording apparatus described above, an air flow may be caused to flow between the deflection electrodes along the deflection electrodes.

In the present invention, in the ink jet recording apparatus described above,
Between the deflection electrodes, the air stream may flow along the droplet flight direction away from the droplet in a direction perpendicular to the facing direction of the deflection electrode.

In the present invention, the ink jet recording apparatus described above can be applied even when the droplets are not charged.

ADVANTAGE OF THE INVENTION According to this invention, the inkjet recording device and method which can be printed at high speed without a printing distortion are realizable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a main part configuration diagram of a continuous discharge type ink jet recording apparatus according to a first embodiment of the present invention. It is an effect explanatory view of the continuous discharge type inkjet recording device which is the 1st example of the present invention. 1 is a cross-sectional view of a main part of a continuous discharge type inkjet recording apparatus according to a first embodiment of the present invention. It is a principal part block diagram of the continuous discharge type inkjet recording device which is the 2nd Example of this invention. It is a principal part block diagram of the continuous discharge type inkjet recording device which is the 3rd Example of this invention. It is a principal part block diagram of the continuous discharge type inkjet recording device which is the 4th Example of this invention. FIG. 6 is a configuration diagram of a main part of a continuous discharge type ink jet recording apparatus according to a fifth embodiment of the present invention. 1 is an overall schematic configuration diagram of an inkjet apparatus to which the present invention is applied. It is a prior art example different from this invention, and is a principal part block diagram for the comparison with this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  First, the overall configuration of an inkjet recording apparatus to which the present invention is applied will be described.

  FIG. 8 is an overall configuration diagram of an inkjet recording apparatus to which the present invention is applied. In FIG. 8, the ink jet recording apparatus includes an ink jet driving unit, an ink density control unit, and a recording medium conveyance control unit.

  The ink jet drive unit deflects the ink jet head 32, the liquid storage tank 43, an AC power supply 47 that supplies an AC voltage to the piezoelectric elements in the ink jet head 32, a charging electrode that applies a charge to each droplet, and the droplet. A control voltage power supply 33 that supplies a voltage to the deflection electrode, pumps 46 and 36 that supply and collect liquid to the inkjet head 32, and a main control device 37 that controls the operation of each unit are provided.

  The ink concentration control unit adjusts the concentration of the liquid in the liquid storage tank 43 supplied to the inkjet head 32. Specifically, a concentration measuring device 40 which is a means for measuring the liquid concentration in the liquid storage tank 43, a solvent storage tank 41 for storing a liquid solvent used for diluting the liquid in the liquid storage tank 43, A pump 42 for supplying the solvent in the solvent storage tank 41 to the liquid storage tank 43 of the ink jet driving unit, and an ink concentration control device 39 for controlling them are provided.

  The recording medium conveyance control unit includes a recording medium conveyance mechanism 45 and a conveyance control device 44.

  In the above configuration, when the main control device 37 of the ink jet driving unit receives pattern data (not shown) to be recorded from the outside, the liquid supply / recovery pumps 46 and 36, the piezoelectric element driving AC power supply 47, the charging voltage / By controlling the control voltage power supply 33 that supplies the deflection voltage, the charging electrode signal voltage is supplied to the charging electrode unit (not shown here) and the deflection electrode signal voltage is supplied to the deflection electrode (not shown here) according to the pattern data to be recorded. Output). Thereby, the discharge of the liquid (ink) is controlled.

  In addition, the main control device 37 of the ink jet drive unit handles the print body 16 by communicating with the transport control device 44 of the recording medium transport control unit. Further, the main control device 37 of the ink jet driving unit communicates with the ink concentration control device 39 of the ink concentration control unit to confirm that the liquid concentration in the liquid storage tank 43 is a predetermined concentration, and to determine the predetermined concentration. Control is performed so as to supply the liquid to the inkjet head 32.

  However, in the ink jet head 32, a droplet shape observation device 49 is installed in the ink formation region, information obtained thereby is fed back to the main control device 37, and an appropriate input calculated based on the fed back information. It may be configured to stabilize the uniform ink ejection by inputting the value into the piezoelectric element.

(First embodiment)
The embodiment of the present invention described below is an example in the case of being applied to a continuous discharge type ink jet recording apparatus among the ink jet recording apparatuses shown in FIG.

  1, 2, and 3 for the schematic structure of the deflection electrode configuration from the nozzle of the inkjet head in the continuous discharge type inkjet recording apparatus (or continuous inkjet apparatus) according to the first embodiment of the present invention. It explains using.

FIG. 1 is a schematic configuration diagram of an essential part of the first embodiment of the present invention, and shows an internal configuration of the inkjet head 32 of FIG. FIG. 2 is a detailed explanatory view near the airflow pipe outlet 17a, and FIG. 3 is a cross-sectional view taken along the line AA in FIG.

  In FIG. 1, an ink jet head of a continuous discharge type ink jet recording apparatus according to the present invention includes a nozzle head 2 having an ink chamber 1 for discharging liquid droplets, and charging electrodes 3 and 8 for individually charging the formed liquid droplets. And a pair of deflecting electrodes 5 and 11 for deflecting the charged droplet by an electric field, and a gutter 13 for collecting the droplet for reuse of the droplet that has not been used for printing. The deflection electrodes 5 and 11 are installed so as to have opposing surfaces parallel to each other. A pipe 17 is installed upstream of the deflection electrode so that its outlet 17 a is along the surface of the deflection electrode 11. FIG. 3 is an AA cross-sectional view.

  FIG. 9 is an example (conventional example) different from the present invention, and shows a comparative example for comparison with the present invention. As shown in the comparative example of FIG. 9, a passage 18 is provided from the ink chamber 1 to the front of the printing body 16 so as to surround the ink incident line 1 ′, and a pipe 17 is connected to the charging electrodes 3 and 8 in this passage 18. Connected near the exit.

  In the configuration shown in FIG. 1, the liquid column 7 ejected from the nozzles of the nozzle head 2 is cut by vibration applied from the upper part of the ink chamber 1 in the nozzle head 2 to form a droplet row as shown in the figure. . Here, the entire casing of the nozzle head 2 is in a grounded state. The formed droplets are formed on the charging electrode substrates 4 and 9 and are negatively charged by the charging electrodes 3 and 8 disposed close to each other so as to be parallel to the flying direction of the droplets.

  Here, the charging electrodes 3 and 8 charge individual droplets according to the target printing mode by applying (applying) arbitrary voltages to the droplets from the charging voltage controller 14 at arbitrary timings. It has a configuration that can.

  At this time, the cutting point of the liquid column 7 (droplets are formed by cutting the liquid column) is located on the charging electrodes 3 and 8 provided corresponding to the droplet rows. ing. Further, it is preferable that the charging electrodes 3 and 8 are arranged so that the droplet row passes near the center in the width direction (direction perpendicular to the drawing sheet).

  Here, a so-called deflection electrode for forming a deflection electric field for deflecting the charged droplets 12 in an arbitrary direction by an electric field is provided below the ink flying direction in the charging process (below the charging electrodes 3 and 8). is set up. These deflection electrodes are composed of a ground deflection electrode 5 (first deflection electrode) and a high-voltage deflection electrode 11 (second deflection electrode), and are arranged in such a manner that they face each other in parallel. Are perpendicular to the deflection electrode surfaces 5 and 11 and are formed parallel to each other.

  In the region where the deflection electric field is formed, droplets (including charged droplets and uncharged droplets) after passing through the charging electrodes 3 and 8 fly, so that the charged droplets 12 are Due to the influence of the deflection electric field, it is deflected in the direction approaching the electrode 11 opposite to the charging code, and lands on the printing body 16 to form a printing pattern. Since a droplet with a large charge amount approaches the positive electrode, the ink incident line 1 ′ is set at a position close to the surface of the grounded deflection electrode 5 in order to print a large character.

  At this time, in the second conventional example of the present invention, when an air flow is caused to flow from the pipe 17 to the passage 18, the air flow merges near the outlets of the charging electrodes 3 and 8, and the air flow directly collides with the droplet 6. The airflow flows in the flying direction of the droplets. Therefore, the relative velocity between the droplet and the gas surrounding the droplet is reduced, the air drag applied to the droplet is reduced, the distance between the droplets is kept constant, and the subsequent droplet catches up with the leading droplet. Although the merger is less likely to occur, the airflow merges in the vicinity of the outlets of the charging electrodes 3 and 8, and the airflow directly collides with the droplet 6. There is a problem that the trajectory of the ink fluctuates and print distortion occurs.

  In the first embodiment of the present invention shown in FIG. 1, a pipe 17 is installed so that its outlet 17 a is radially away from the ink incident line 1 ′ and along the surface of the deflection electrode 11, and flows through the pipe 17. The airflow 19 does not directly collide with the droplet 6 as a jet, but the deflection electrode surface is ejected along the ink incident line 1 ′, and the airflow 20 around the droplet 6 is attracted as shown in FIG. Since the airflow does not directly collide with the droplet 6 in this way, there is an effect that the turbulence of the airflow 20 around the droplet 6 is small. If the pipe outlet 17 a and the ink incident line 1 ′ are separated from the diameter of the droplet 6 by at least twice, there is an effect that no disturbance is generated.

  For example, the length of the electrodes 5 and 11 is preferably about 27.5 mm. The distance between the electrodes 5 and 11 is preferably about 3 mm. In the example of FIG. 1, the left side of the drawing is described as the ground deflection electrode 5, and the right side is described as the high voltage deflection electrode 11, but the voltage applied to these deflection electrodes is, on the contrary, the deflection electrode. 11 may be grounded and the deflection electrode 5 may be set to a negative voltage. Needless to say, when the ink droplet is charged positively, the voltage of the deflection electrode is reversed.

  An electric field shield member 10 is installed between the charging electrodes 3 and 8 and the deflection electrodes 5 and 11 for the purpose of blocking the influence of the electric field from the high voltage deflection electrode 11. The electric field shield member 10 is composed of a conductive member. As shown in FIG. 1, the electric field shield member 10 exerts an influence of an electric field due to a high voltage on the charging electrodes 3 and 8 and the periphery thereof. It is preferable to be in a grounded state so as not to occur.

  The velocity of the airflow 19 ejected from the pipe outlet 17a is preferably close to the velocity of the droplet 6, but even a velocity about half the velocity of the droplet has a sufficient effect.

  With this configuration, the turbulence of the air current around the droplet 6 is reduced, the distance between the charged droplets is not shortened, printing distortion is reduced, and dummy uncharged droplets are inserted between the charged droplets. Therefore, there is an effect that high-speed printing is possible. Specifically, there is an effect that a printing speed twice as high as that of the conventional case where a dummy uncharged droplet is inserted between a charged droplet and a charged droplet for printing can be obtained.

  Further, the example in which the droplet is charged has been described above, but the present invention can also be applied to a case where the droplet is not charged. When droplets such as a resin used for 3D printing are caused to fly, the liquid cannot be charged, but it is possible to prevent the interval between the droplets from being shortened and to have a similar effect.

As described above, according to the first embodiment of the present invention, it is possible to realize an ink jet recording apparatus capable of high-speed printing without printing distortion.

(Second embodiment)
Next, a second embodiment of the present invention will be described.

  FIG. 4 is a block diagram showing the principal part of the second embodiment of the present invention. Other configurations not shown in FIG. 4 are the same as those in the example of FIG. In FIG. 4, since the airflow flows in the space surrounded by the deflection electrodes 5 and 11 and the cover 22, the airflow 19 does not spread out of the deflection electrode, and the speed does not decrease.

According to the second embodiment of the present invention, the same effect as that of the first embodiment can be obtained with the air flow 19 at a lower speed.

(Third embodiment)
Next, a third embodiment of the present invention will be described.

    In FIG. 5, the outlet of the pipe is divided into 17a and 17b, and between the deflecting electrodes 5 and 11, an air stream flows along the droplet flight direction away from the droplet 6 in a direction perpendicular to the facing direction of the deflecting electrode.

  By configuring in this way, it is possible to attract an air flow having a uniform velocity in the deflection direction, and it is possible to reduce printing distortion of larger characters.

  According to the third embodiment of the present invention, the same effect as that of the first embodiment can be obtained, and a larger character can be formed.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described.

  FIG. 6 is a block diagram showing the principal part of the fourth embodiment of the present invention. Other configurations not shown in FIG. 6 are the same as those in the example of FIG.

In FIG. 6, the deflecting electrode 11 is connected to the deflecting electrode 5 and an opening 11a at an angle so as to print a high character. An outlet 17 a ′ of another pipe 17 ′ is connected between this 11 a and the electrode 5. By configuring in this way, there is an effect of preventing a gap between the deflection electrodes from being opened and a reduction in the speed of the airflow.
(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described.

  FIG. 7 is a block diagram showing the principal part of the fifth embodiment of the present invention. Other configurations not shown in FIG. 7 are the same as those in the example of FIG.

  In FIG. 7, the cover 23 covers the periphery of the main configuration of FIG. An air purge pipe 21 is inserted into the cover 23 from the outside, and a pipe port 21a is opened to the cover inner space. A pipe 17 is connected to the pipe 21. With this configuration, part of the air that cleans the vicinity of the inkjet head by air purge can be used to add airflow around the droplets, and the structure is simplified.

  As described above, by blowing away the air flow in the radial direction away from the droplet flight path, which is described in detail, the air flow is attracted by this air flow, and an air flow is generated around the droplet. However, according to the continuous discharge type ink jet recording apparatus and method in which the velocity of the droplet and the relative velocity of the surrounding air flow are reduced and the air drag force of the droplet is reduced, Since the distance between the droplets is not shortened, the printing distortion is reduced, and there is no need to insert dummy uncharged droplets between the charged droplets, so that there is an effect that printing can be performed with high accuracy and high speed.

  DESCRIPTION OF SYMBOLS 1 ... Ink chamber, 1 '... Ink incident line, 2 ... Nozzle head, 3 ... Charge electrode, 4, 9 ... Charge electrode substrate, 5 ... Deflection electrode, 6 ... Droplets, 7 ... liquid column, 8 ... charging electrode, 10 ... electric field shield member, 11, 11a ... deflection electrode, 12 ... droplet (charging), 13 ... gutter , 14 ... charging voltage controller, 15 ... deflection voltage controller, 16 ... printing body, 17 ... piping, 17a ... piping outlet, 17 '... piping, 17a' ... piping Outlet, 18 ... passage, 19 ... airflow, 20 ... attracted airflow, 21 ... air purge piping, 21a ... piping port, 22 ... cover, 23 ... cover,

Claims (7)

Incidence of ink droplets in an ink jet device for recording characters or the like on a recording object that moves relative to a direction substantially perpendicular to the ejection direction, means for ejecting ink droplets, means for generating a recording signal according to recording information An ink jet apparatus characterized in that an air flow is caused to flow away from a line and along a flight direction, and an air flow is generated around the ink droplet in the flight direction.
Means for ejecting ink droplets; means for generating a recording signal in accordance with recording information; means for charging ink droplets based on the recording signal; and means for deflecting the flying direction of the charged ink droplets. In an ink jet recording apparatus that records characters on a recording object that moves in a direction substantially perpendicular to the deflection direction, an air current is made to flow away from the incident line of the ink droplet and along its flight direction, and around the ink droplet An ink jet recording apparatus characterized by generating airflow in the flight direction.
3. The ink jet recording apparatus according to claim 1 or 2, wherein an air current that flows away from the ink droplet and in a flight direction thereof is made to flow along the surface of the deflection electrode.
4. The ink jet recording apparatus according to claim 1, wherein a cover is provided outside the deflection electrodes.
The inkjet recording apparatus according to any one of claims 1 to 4,
In the space between the deflection electrodes, the air current that flows away from the ink droplets and in the direction of flight,
Ink jet recording characterized in that in the space perpendicular to the facing surface of the deflection electrode, an air stream flows in the flying direction away from the ink droplets in the downstream direction, and an air stream is generated in the flying direction around the ink droplets. apparatus.
6. The ink jet recording apparatus according to claim 1, wherein an air flow is replenished downstream from a spreading area between the deflection electrodes.
The inkjet recording apparatus according to any one of claims 1 to 6,
An ink jet recording apparatus characterized in that a part of gas for purging the inside of a cover is used as an air current flowing away from an ink droplet and in its flight direction.