JP6553958B2 - Ink jet recording apparatus and control method of ink temperature used therefor - Google Patents

Description

  The present invention relates to an industrial inkjet recording apparatus, and more particularly to control of an ink temperature suitable for ink particle generation at ambient temperature.

  In general, an ink jet recording apparatus that converts continuously jetted ink into particles, charges and deflects particles necessary for character creation, and does not charge and deflect particles that are not used for printing. The uniformity of the ink particles ejected from the nozzle body is greatly affected by the print quality. In order to stabilize the printing quality, for example, Japanese Patent Laid-Open No. 11-58770 (Patent Document 1) discloses an arrangement in which an ink heating device for heating ink is provided on the front side of the nozzle. .

Japanese Patent Application Laid-Open No. 11-58770

  Although Patent Document 1 discloses that the temperature of the ink is controlled in order to optimally maintain the formation of good ink particles that affect the print quality, the addition of ink from the time it jets up to the printable ink viscosity is disclosed. It does not consider warm time. In addition, the nozzle main body is made of metal, and there is a problem that heat is easily taken away and it takes time to heat it.

  An object of the present invention is to provide an ink jet recording apparatus which ejects ink and heats it in a short time until reaching a target ink temperature with a simple configuration, and a control method of ink temperature used therefor.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. Although the present application includes a plurality of means for solving the above problems, one example is a main body containing a control part and a circulating part, a print head generating ink particles, a main body and a print head An ink jet recording apparatus having a cable to be connected, wherein the print head includes a nozzle body that generates and ejects ink particles, a heater unit for warming the ink supplied to the nozzles, and an ink circulation that circulates the ink from the nozzle body It has a pipe, and the main body constitutes an ink circulation path consisting of an ink circulation valve, an ink circulation pump, and a main ink container connected in communication by an ink circulation pipe via a cable as a circulation part. When heating the ink by the heater unit, the heated ink is flowed to the ink circulation path to flow rate control.

  Even if the environmental temperature changes, an ink jet recording apparatus which can supply an ink temperature which is an ink viscosity necessary for making the ink into particles in a short time by an inexpensive constitution and can perform excellent printing and control of the ink temperature used therefor We can provide a way.

FIG. 1 is an overall schematic view of an ink jet recording apparatus according to a first embodiment. FIG. 2 is a path configuration diagram of the ink jet recording apparatus in Embodiment 1. FIG. 6 is a view showing the opening and closing time of the ink circulation valve in the first embodiment. FIG. 5 is a diagram illustrating an example of an ink temperature increase characteristic depending on an opening / closing time of an ink circulation valve in the first embodiment. FIG. 6 is a flowchart of ink heating control in Embodiment 1. FIG. 7 is a diagram comparing arrival times of a switching target temperature and a target ink temperature in the case of the intermittent opening and closing of the ink circulation valve and the closing state in the first embodiment. FIG. 7 is a path configuration diagram of the ink jet recording apparatus in Embodiment 2.

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

  First, an overall overview of the ink jet recording apparatus will be described with reference to FIG. FIG. 1 is an overall schematic diagram of an ink jet recording apparatus according to the present embodiment. In FIG. 1, the ink jet recording apparatus includes a main unit 1 containing the control unit 2 and the circulation unit 3 therein, a print head unit 5 for generating ink particles 16 necessary for printing, the main unit 1 and the print head It is comprised by the cable 4 which connects the part 5. FIG.

  Hereinafter, the path configuration in the ink jet recording apparatus will be described with reference to FIG. FIG. 2 is a diagram showing the path configuration of the ink jet printing apparatus according to the present embodiment, showing mainly the path configuration of the circulation unit 3 built in the main unit 1. In FIG. 2, the main ink container 6 is filled with the ink 7a. The main ink container 6, the ink supply valve 8, the ink supply pump 9, the ink filter 10, the ink pressure regulating valve 11 for adjusting the ink pressure, the heater unit 12 and the nozzle body 13 are connected in communication by the ink supply pipe 14. The gutter 18 for recovering the particles 15, the ink recovery pump 19, and the main ink container 6 are communicatively connected by an ink recovery pipe 20. Further, in order to circulate the ink 7 a from the nozzle body 13, the ink circulation pump 21, the ink circulation valve 22, and the main ink container 6 are communicatively connected by the ink circulation pipe 23 to constitute an ink circulation path.

  Further, the sub ink container 24 is filled with the ink 7 b, and the ink supply valve 25 and the ink supply pump 9 are communicatively connected by the ink supply pipe 26. The intensifying fluid container 27 is filled with the intensifying fluid 28, and the intensifying fluid 28 and the intensifying pump 29 and the intensifying fluid replenishing valve 30 are communicatively connected by an intensifying fluid replenishing pipe 31.

  Next, the operation will be described. The ink 7 a filled in the main ink container 6 is supplied by the supply pump 9 through the ink supply pipe 14. The ink pressure adjustment valve 11 adjusts the supplied pressurized ink 7 a to a predetermined pressure, and the pressure-adjusted ink is supplied to the nozzle body 13 through the heater unit 12.

  The ink 7 a supplied to the nozzle body 13 and pressurized is jetted from the tip of the nozzle body 13 and becomes ink particles 15 due to the surface tension of the ink. The ink particles 15 are charged to a charge amount according to the character information by the charging electrode 16, and deflected by the deflection electrodes 17a and b (a: plus electrode, b: minus electrode) to print on a printing object (not shown). . Further, ink particles 15 not used for printing are captured by the gutter 18 and recovered through the ink recovery pipe 20 to the main ink container 6 by the ink recovery pump 19, and the ink 7 a circulated from the nozzle body 13 is transported through the ink circulation pipe 23. The ink is returned to the main ink container 6 for reuse by the viscometer (not shown), the ink circulation valve 22, and the ink circulation pump 21.

  FIG. 3 is a diagram showing the opening / closing time of the ink circulation valve in the present embodiment. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates opening / closing of the ink circulation valve 22. In this embodiment, in order to heat the ink in the nozzle in a short time, it is necessary to adjust the flow rate of the ink passing through the nozzle, and the time 34 for opening the ink circulation valve 22 and the time 35 for closing the valve The flow control is performed by the cycle 36 of the open / close time. That is, when ink is heated, the ink is flowed to the ink circulation path to control the flow rate. The ratio of the open time 34 to the period 36 is called a duty ratio. Here, the intermittent opening and closing of the ink circulation valve 22 is repeated at period 36 until the target temperature of the ink is reached by heating by the heater unit, and the ink circulation by the ink circulation path is performed and printing is on standby. Then, when the target temperature is reached, the intermittent opening / closing of the ink circulation valve 22 is stopped, the ink circulation is stopped, and the printing mode is switched.

  Also, by setting the cycle 36 to a cycle not synchronized with the frequency of the ink circulation pump 21, it is possible to suppress the fluctuation of the ink flow rate. For example, if the frequency of the ink circulation pump 21 is 4 Hz, it is preferable to set the period to a frequency that is not divisible by 4 such as 7 Hz, or an integral multiple of that frequency.

  FIG. 4 is a diagram illustrating an example of the ink temperature increase characteristic depending on the opening / closing time of the ink circulation valve. In FIG. 4, each curve shows a rising curve of the ink temperature when the opening and closing time of the ink circulation valve is changed. That is, the rising curve of the ink temperature is 37 when the ink circulation valve 22 is always closed and the ink circulation path is not used. On the other hand, when the opening time of the ink circulation valve 22 is long and the closing time is short, the rising curve of the ink temperature is 38, for example, when the duty ratio of the opening time is 10%. In the case of the curve 38, since the flow rate of the ink circulation path is larger than in the case of the curve 37, the amount of ink passing through the inside of the heater unit increases and the amount of ink to be heated increases. The circulation amount of the ink increases, the temperature rising effect is quickened by the heat retaining effect of the warmed ink, and the ink temperature in the nozzle rises in a short time. On the other hand, the ink temperature at the time of saturation is low because it flows before it warms up due to the large flow rate. In addition, the increase curve of the ink temperature when the open time is shortened and the close time is extended, for example, when the duty ratio of the open time is 5%, is 39. In that case, the flow rate is higher than that of the closed curve 37. Since the temperature rise is fast because the temperature is high, since the flow rate is small compared to the case of the curve 38, the temperature at the time of saturation is easily deprived of heat by the nozzle, and the temperature at the time of saturation becomes low. When the opening time and closing time are set to a time between the curves 38 and 39, for example, the rising temperature of the ink temperature is 40 when the duty ratio of the opening time is 7%, and the ink temperature in the nozzle is Is higher than the curve 37 in the closed state, and the ink temperature at saturation approaches the curve 37 in the closed state.

  FIG. 5 shows a flowchart of the ink heating control in the present embodiment. In FIG. 5, when the ink jet recording apparatus is activated (step S01), the ambient temperature is detected as needed by a temperature detector (not shown) built in the apparatus main body (S02). When the ink is ejected based on the detected ambient temperature, the heater unit 12 is operated if the temperature is lower than the temperature set under the respective conditions (S03), and if it is the set temperature or more, the state shifts to a printable state (S10) . When the operating ambient temperature falls below the set temperature and the heater unit 12 operates, the heater built in the heater unit 12 is operated with high power (S03). Next, as shown in FIG. 3, the ink circulation valve 22 is intermittently opened and closed by flow control with the opening time 34 and closing time 35 and the opening and closing time 36 (cycle) to circulate the warmed ink. (S04, S05). Thereafter, it is judged whether the warmed ink has reached the ink temperature for switching from the heating state by the high applied voltage to the target ink temperature control (S06), and when the temperature is reached, the ink circulation valve 22 is closed ( S07). Thereafter, the printing is made to wait until the target ink temperature is reached by the heater unit (S08, S09), and when the target temperature is reached, the state shifts to a printable state (S10).

  Also, the ambient temperature is measured at any time (S11), it is determined whether the temperature has changed (S12), and if the temperature changes, the target ink temperature is controlled by the heater unit (S13). It is set as a state (S10).

  FIG. 6 is a diagram comparing arrival times of the switching target temperature and the target ink temperature in the case of the intermittent opening and closing of the ink circulation valve 22 and the closing state. In FIG. 6, as described in FIG. 4, the ink circulation valve 22 is closed and the ink circulation path is not used by optimizing the duty ratio of the opening time 34 using the ink circulation path. It is possible to shorten the arrival time of the switching target temperature and the target ink temperature. Here, the switching target temperature refers to a state where the heater unit is operated with high power and heated, and the flow control is performed by the intermittent opening and closing of the ink circulation valve 22, the intermittent opening and closing of the ink circulation valve 22 is stopped and the ink is closed. It is a target temperature for switching to a state of controlling to the target ink temperature by temperature control of the heater unit without using the circulation path. Here, a temperature higher than the final target ink temperature is set as the switching target temperature.

  As described above, according to the flow control method based on the period 34 for opening and closing the ink circulation valve 22 and the period 36 for closing the opening and closing time, the ink circulation valve 22 is closed and the ink circulation path is not used. There is an effect that it is possible to shorten the warming time.

  As described above, the present embodiment is an ink jet recording apparatus having a main body including a control unit and a circulation unit, a print head generating ink particles, and a cable connecting the main body and the print head. The print head has a nozzle body that generates and ejects ink particles, a heater unit for warming the ink supplied to the nozzles, and an ink circulation pipe that circulates the ink from the nozzle body. An ink circulation path consisting of an ink circulation valve, an ink circulation pump, and a main ink container, which are communicatively connected by an ink circulation pipe via a cable as a part, constitutes the ink circulation path when the heater unit heats the ink. The flow rate is controlled by flowing the heated ink through the circulation path.

  A method of controlling ink temperature of an ink jet recording apparatus, which generates ink particles and ejects the ink particles from a print head to perform printing, and controls the flow rate of ink heated by the heating device. Configure.

  As a result, even if the environmental temperature changes, it is possible to supply the ink temperature, which is the ink viscosity necessary to make the ink into particles, in a short time with a low cost configuration, and an ink jet recording apparatus capable of excellent printing. It can provide a temperature control method. In addition, it has a great effect on a small-diameter orifice with a small ejection amount and a high ink viscosity.

  FIG. 7 is a diagram illustrating a path configuration of the ink jet recording apparatus according to the present embodiment. 7 differs from FIG. 2 in that an ink heating circulation valve 32 and an ink heating circulation pipe 33 are provided, and the heater unit 12, the nozzle main body 13, the ink circulation pump 21 and the ink heating circulation valve 32 It is a point which is connected by the thermal circulation pipe 33 to constitute an ink heating circulation path, and the ink is circulated.

  As a means of shortening the time for warming the ink, the ink circulation valve 22 is closed and the ink is circulated through the short piping in the ink heating circulation pipe 33, whereby the heat radiation amount can be reduced, and it is necessary for the ink heating. Time can be shortened. At this time, by intermittently opening and closing the ink heating and circulating valve 32 as described in the first embodiment, it is possible to shorten the time required for the ink heating.

  As described above, the present embodiment is an ink jet recording apparatus having a main body including a control unit and a circulation unit, a print head generating ink particles, and a cable connecting the main body and the print head. The print head has a nozzle body that generates and ejects ink particles, a heater unit for warming the ink supplied to the nozzles, and an ink circulation pipe that circulates the ink from the nozzle body. As a part, an ink circulation pump and an ink heating and circulating valve connected in communication with an ink circulation pipe via a cable and an ink heating and circulating valve are connected to a heater unit by an ink heating and circulating pipe to constitute an ink heating and circulation path. At the time of heating of the ink by the heater unit, the heated ink is flowed to the ink heating circulation path, and flow rate control is performed.

In the above-described embodiment, the ink circulation valve 22 and the ink heating circulation valve 32 are provided with a throttle member in place of, or together with, a valve that performs intermittent opening / closing control for flow rate adjustment. It is not necessary to use a solenoid valve that can control intermittent switching for this purpose, or the load on the solenoid valve can be reduced.
Also, in order to print stable characters, it is necessary to reduce the change in the ejection velocity of the ink with respect to the change in the ink temperature. The reason is that it is the production of ink particles suitable for printing stable characters, and the particle formation constant influences the production of the particles. This particle constant is a function of the ink ejection speed. The ink ejection speed is small when the viscosity of the ink is low, and is large when the viscosity is high. By controlling the ink viscosity to be substantially constant with respect to changes in the ink temperature, the ink ejection speed becomes substantially constant, and it becomes possible to print characters that are stable over a wide range of operating temperatures.

  The present invention is not limited to the above-described embodiments, and includes various modifications. Further, the above-described embodiments are described in detail to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 ... Main-body part (ink-jet recording device), 2 ... Control part, 3 ... Circulation part, 4 ... Cable, 5 ... Print head part, 6 ... Main ink container, 7a, b ... Ink, 8 ... Ink supply valve, 9 ... Ink supply pump 10: ink filter 11: ink pressure control valve 12: heater unit 13: nozzle body 14: ink supply pipe 15: ink particle 16: charging electrode 17a, b: deflection electrode 18: 18 Gutter, 19: ink collection pump, 20: ink collection pipe, 21: ink circulation pump, 22: ink circulation valve, 23: ink circulation pipe, 24: sub ink container, 25: ink supply valve, 26: ink supply pipe, 27 28: auxiliary fluid container 28: auxiliary fluid, 29: auxiliary pump, 30: supplemental fluid supply valve, 31: supplemental fluid supply pipe, 32: ink heating circulation valve, 33: ink heating circulation pipe, 34 ... circulation Open time of 35, ... Closed time of circulation valve, 36 ... Open / close time (cycle), 37 ... Temperature rise curve in case of closed state of circulation valve, 38 ... Open time of circulation valve: long, closed time: short case Temperature rising curve, 39 ... opening time of circulation valve: short, closing time: temperature rising curve in case of long, 40 ... opening time of circulation valve: medium, closing time: temperature rising curve in case of

Claims (2)

An ink jet recording apparatus, comprising: a main body including a control unit and a circulating unit; a print head generating ink particles; and a cable connecting the main body and the print head.
The print head includes a nozzle body for generating and ejecting ink droplets, has a heater unit for heating ink to be supplied to the nozzle body, the ink ink circulation tube for circulating from the nozzle body,
The main body portion forms an ink circulation path including an ink circulation valve, an ink circulation pump, and a main ink container, which are communicably connected by the ink circulation pipe via the cable as the circulation portion.
Wherein, when the heating of the ink by the heater unit, no line flow control flow of ink which is the pressurized temperature of the ink circulation path by repeating the opening and closing of said ink circulating valve, the ink temperature within a predetermined temperature 3. The ink jet recording apparatus according to claim 1, wherein the ink circulation valve is repeatedly opened and closed until reaching the predetermined temperature, and the ink circulation valve is closed when the predetermined temperature is reached . An ink jet recording apparatus, comprising: a main body including a control unit and a circulating unit; a print head generating ink particles; and a cable connecting the main body and the print head.
The print head includes a nozzle body that generates and ejects ink particles, a heater unit for heating ink supplied to the nozzle body, and an ink circulation pipe that circulates ink from the nozzle body.
The main body has an ink circulation pump and an ink heating circulation valve that are connected to each other by the ink circulation pipe via the cable as the circulation part, and is connected to the heater unit by an ink heating circulation pipe. Comprising
The control unit, wherein when warming of the ink that by the heater unit, an ink jet recording apparatus characterized by controlling the flow rate flowing the pressurized hot ink to said ink heating circulation path.

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