KR20070011797A - Array type inkjet head - Google Patents

Abstract

An array type ink-jet head is provided to actively cool a head chip if the temperature of the head chip is higher than a predetermined value and to supplementarily heat the head chip together with a heat radiating body if the temperature of the head chip is lower than the predetermined value. An array type ink-jet head includes an ink tank, an ink channel unit(100), a head chip(400), and a temperature control unit. The ink channel unit forms an ink supply passage from the ink tank to the head chip. The head chi includes a plurality of nozzles. The temperature control unit includes a boss making contact with the rear surface of the head chip and conducting heat, a heat sink section integrally connected to the boss and having a base section conducting heat, and a thermocouple device section heating or cooling the heat sink section.

Description

Array type inkjet head {Array type inkjet head}

1 is a side cross-sectional view of an inkjet image forming apparatus having an array type inkjet head according to the present invention.

2 is a perspective view showing the appearance of an array type inkjet head according to the present invention;

3 is a side sectional view showing the inside of an array type inkjet head according to the present invention;

4 is an assembled perspective view of the temperature control unit according to the present invention;

5 is a cross-sectional view showing a coupling state of a head chip and an ink channel unit according to the present invention;

<Description of the symbols for the main parts of the drawings>

12 ... Nozzle section 100 ... ink channel unit

101 ... first channel plate 102 ... second channel plate

103 ... 3rd channel plate 110 ... fastening hole

120 ... FPC 140 ... head chip seat

160 ... protruding groove 190, 690 ... ink hole

400 ... head chip 410a, 410b, 410c, 410d ... nozzle

420 ... FPC terminal 470 ... Temperature sensor

485 control panel 600 heat sink

640 ... base 660 ... projection

700 ... thermoelectric element

The present invention relates to an inkjet head, and more particularly, to an array type inkjet head capable of adjusting the temperature of a head chip.

The inkjet head uses thermal energy, a piezoelectric element, or the like as a power source for ink ejection. The nozzle portion provided on the head chip of the inkjet head and spraying ink droplets is manufactured to have high resolution by semiconductor manufacturing processes such as etching, vapor deposition, and sputtering.

In general, an inkjet image forming apparatus is spaced a predetermined distance from an upper surface of a printing medium, and forms an image by ejecting ink from an inkjet head reciprocating in a direction perpendicular to a conveying direction of the printing medium. The ink jet head for injecting ink onto the print medium while being transferred in a direction perpendicular to the transfer direction of the print medium is referred to as a shuttle type ink jet head.

In recent years, there is an inkjet image forming apparatus using an array type inkjet head having a nozzle portion having a length corresponding to the width of a print medium without the inkjet head being reciprocated. In such an array type inkjet head, the inkjet head is fixed without being reciprocated and only the print medium is transferred in one direction. Therefore, the driving device is simple and high speed printing is possible.

However, in an array type image forming apparatus having a relatively high printing speed and a high driving frequency of an inkjet head, much more heat is generated in a printing operation than a shuttle type inkjet printer, and this heat is accumulated in the head chip. As the ink ejection from the nozzle portion continues, more heat is accumulated in the head chip, which adversely affects the behavior of the ink droplets. If the degree of overheating of the head chip is severe, ink may vaporize at an undesired timing and a boiling bubble may occur, resulting in disturbance of driving frequency and deterioration of print quality. Therefore, it is necessary to provide a heat sink for dissipating heat accumulated in the head chip to the surroundings. In addition, when the temperature of the head chip is a predetermined value or more, there is a need for additional head chip cooling means for actively cooling the head chip to maintain the temperature of the head chip within a predetermined range.

On the other hand, in order to reduce the warm-up time required from the stand-by state to the ink ejectable temperature, the temperature rise time of the head chip must be reduced. For this purpose, if the temperature of the head chip is less than a predetermined value, a means for auxiliary heating of the head chip together with a heating element for generating ink ejection force is required.

In addition, when heat is accumulated locally on a specific head chip in an array type inkjet head having a plurality of head chips, ink ejection characteristics of each head chip are different from each other, and accurate driving control of each head chip is difficult, resulting in printing. Since the quality deteriorates, it is necessary to maintain a uniform temperature distribution throughout the arrangement of the head chips.

The technical problem of the present invention is to improve the above-mentioned problem, and to dissipate heat accumulated in the head chip to prevent the head chip from overheating, and to actively cool the head chip when the temperature of the head chip is greater than a predetermined value. On the contrary, if the temperature of the head chip is less than a predetermined value, the head chip can be heated together with the heating element, and an array type inkjet head capable of uniformly controlling the temperature distribution over the entire array of the head chip is provided. .

In order to achieve the above object, the array type inkjet head according to the present invention,

An ink tank for storing ink;

An ink channel unit for forming an ink supply path from said ink tank to a head chip;

A back chip fixed to a surface of the ink channel unit to receive ink, and a front head having a plurality of nozzles for ejecting ink, the head chips being arranged in plurality;

A temperature in contact with the back surface of each of the head chips, a heat sink unit which is integrally connected to both the protrusions and a heat conduction unit provided with a base unit that conducts heat, and a thermoelectric element unit that heats or cools the heat sink unit. Control unit; Characterized in that it comprises a.

In one embodiment, the thermoelectric element portion,

It is preferably attached to the base portion.

In one embodiment, the heat sink,

It is preferable that it is provided as a metallic material containing at least one of copper and aluminum.

In one embodiment, the heat sink is provided inside the ink channel unit, the base portion includes a flat plate extending by the length of the array of the head chip, the projection is projected on the upper surface of the flat plate and the head chip It is preferred to include a plurality of rectangular ribs in contact with the back side of the.

In one embodiment, the temperature control unit,

A temperature sensor measuring a temperature of the head chip;

A control unit for driving the thermoelectric element unit as a heating source or a cooling source according to the temperature of the head chip; It is preferable to further provide.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention. Embodiments of the invention are not limited to what is shown in the accompanying drawings, it is to be understood that various modifications can be made within the scope of the same invention. In addition, the same reference numerals denote the same components.

1 is a side cross-sectional view of an inkjet image forming apparatus having an array type inkjet head according to the present invention. Referring to this, the array type inkjet head 52, the paper feed cassette 20 for storing the print medium P, the pickup roller 17 for picking up the print medium P one by one, and the picked up print medium P Feeding rollers 15a and 15b to be transferred to the nozzle unit 12, the maintenance area 80 facing the inkjet head 52 with the print medium P therebetween, and the printed print medium P are discharged. The discharge roller (13a, 13b) to be shown, the loading table 30 is loaded with the printing medium (P) is discharged.

The printing medium P is conveyed in the x direction (hereinafter referred to as the sub scanning direction), and the y direction (hereinafter referred to as the main scanning direction) is the width direction of the printing medium P. The inkjet head 52 has a body 10 having ink tanks 21, 22, 23, 24, see FIG. 3 for storing ink, and a nozzle portion 12 for ejecting ink. The discharge roller 13 includes a star wheel 13a installed in the width direction of the print medium P, and a support roller 13b facing the support wheel 13 to support the rear surface of the print medium P. Since the star wheel 13a is in point contact with the upper surface of the printing medium P, the star wheel 13a may be sprayed onto the upper surface of the printing medium P to prevent contamination of an ink image that is not yet dry. Since high speed printing is performed, if the next printing medium P is loaded before the ink on the upper surface of the printing medium P loaded on the mounting table 30 dries, the back surface of the printing medium P may be contaminated with ink. . In order to prevent this, a separate drying device (not shown) may be further provided. The nozzle unit 12 is capped to prevent the ink stored in the inkjet head 52 from drying out, the ink remaining on the surface of the nozzle unit 12 is wiped, or the nozzle unit 12 is not blocked. The fitting operation is performed in the maintenance area indicated by reference numeral 80.

2 is a perspective view showing the appearance of an array type inkjet head according to the present invention. 3 is a side cross-sectional view showing the inside of an array type inkjet head according to the present invention. Referring to this together, the inkjet head 52 includes a body 10, a nozzle unit 12, and an ink channel unit 100.

The body 10 includes a plurality of ink tanks 21, 22, 23, and 24 storing ink for printing, and a plurality of pressure adjusting units 31 connected to each of the plurality of ink tanks 21, 22, 23, and 24. 32, 33, 34). In the case of a color printable inkjet image forming apparatus, the plurality of ink tanks 21, 22, 23, and 24 may use, for example, yellow (Y), magenta (M), cyan (C), and black (K) inks. Each is stored. The plurality of pressure adjusting units 31, 32, 33, and 34 serve to generate negative pressure to prevent leakage of ink.

Since the length of the nozzle unit 12 corresponds to the width of the print medium P, the print data is printed at one time along the main scanning direction, which is the width direction of the print medium P. FIG. The nozzle unit 12 includes a head chip 400 arranged in plural. For color image printing, four kinds of inks of different colors, for example, C: cyan, M: magenta, Y: yellow, and black: K Four types of nozzles 410a, 410b, 410c, and 410d are provided in the head chip 400 so as to spray the nozzles. The head chip 400 is connected to a CPU, which is a central computing unit of the inkjet image forming apparatus, through a flexible printed circuit (FPC 120), receives a driving signal, and receives power for ink jetting. The FPC 120 is soldered to the FPC terminal 420 provided on the head chip 400.

In one embodiment, the ink channel unit 100 is fixed to the body 10 of the inkjet head 52 by a fastening member (not shown) through the fastening hole 110. The ink channel unit 100 forms an ink passage from the ink tanks 21, 22, 23, 24 provided in the body 10 to the nozzles 410a, 410b, 410c, 410d provided in the head chip 400. . The ink channel unit 100 is connected to the pressure regulators 31, 32, 33, and 34, and flows from the ink tanks 21, 22, 23, and 24 through the pressure regulators 31, 32, 33, and 34. It serves to supply the ink to each of the plurality of head chips 400.

In one embodiment, the ink channel unit 100 has a structure in which the first channel plate 101, the second channel plate 102, and the third channel plate 103 are sequentially stacked. Without being limited thereto, the ink channel unit 100 may be composed of one, two, or four or more channel plates.

Ink channels (not shown) through which ink passes are formed in each of the first, second, and third channel plates 101, 102, 103. The first, second, and third channel plates 101, 102, and 103 may be formed of a polymer material. In one embodiment, by injection molding a liquid crystal polymer (LCP) material, each of the first, second, and third channel plates 101, 102, 103 is manufactured. The liquid crystal polymer (LCP) material has a small coefficient of thermal expansion, thereby minimizing thermal expansion of each of the first, second, and third channel plates 101, 102, and 103 due to heat generated during operation of the inkjet head 52. have. Good dimensional limitability, excellent heat resistance, and low transmittance can prevent inks of different colors passing through the ink channel from mixing with each other. Since the moldability is good, a fine ink channel can also be easily formed. The ink channel unit 100 in which the fine ink channel is formed is greatly reduced in the case of injection molding using a polymer as described above, for example, than manufactured by cutting or pressing a metal material. The first, second and third channel plates 101, 102 and 103 are adhered to each other by a predetermined adhesive member (for example, a thermosetting adhesive containing an epoxy resin).

4 is an assembled perspective view of the temperature control unit according to the present invention. 5 is a cross-sectional view illustrating a coupling state of the head chip 400 and the ink channel unit 100 according to the present invention. Referring to this together, the temperature control unit includes a heat sink 600, a thermoelectric element 700, a temperature sensor 470, and a controller 485. In one embodiment, the temperature control unit cools the head chip 400 when the temperature of the head chip 400 is higher than a predetermined value. In an embodiment, the temperature control unit auxiliaryly heats the head chip 400 together with the heating element 450 when the temperature of the head chip 400 is lower than a predetermined value.

In an embodiment, the first channel plate 101 includes an ink hole 190 for supplying ink, which flows from the ink tanks 21, 22, 23, and 24 into the ink channel unit 100, to the head chip 400. Is formed. In the case of the color printable inkjet head 52, since the nozzles 410a, 410b, 410c, and 410d are arranged in four rows on the head chip 400, four ink holes 190 are also formed for each color.

The back surface of the head chip 400 is adhered to the seating portion 140 of the head chip 400 formed on the surface of the first channel plate 101. An adhesive having good thermal conductivity is used for the adhesive layer 460. A plurality of nozzles 410a, 410b, 410c, and 410d for ejecting ink are formed on the front surface of each of the head chips 400. Ink is supplied to the back surface of each of the head chips 400. The head chip 400 includes a heating element 450 and heats ink to generate bubbles, thereby generating ink jetting force. As the head chip 400 according to the present invention, various types of embodiments capable of spraying ink onto the print medium P are not limited to those shown in the accompanying drawings.

The liquid crystal polymer used as the material of the ink channel unit 100 has a very low thermal conductivity (generally, the thermal conductivity is less than about 1 W / m-K). Therefore, in the case of repeated high speed printing, heat generated in the heating element 450 is accumulated in the head chip 400 without being dissipated to the surroundings, and the head chip 400 may be overheated. The heat sink 600 may dissipate heat accumulated around the head chip 400 to prevent overheating of the head chip 400 to prevent overheating.

The heat sink 600 includes a protrusion 660 contacting the rear surface of each of the head chips 400 and a base 640 which is integrally connected to both the protrusions 660 and conducts heat. . The heat sink 600 is provided of a material having good thermal conductivity. In one embodiment, the heat sink 600 is preferably made of a metallic material including at least one of copper and aluminum.

The heat sink 600 is located on the rear surface of the first channel plate 101 and is provided inside the ink channel unit 100. An ink hole 690 is formed in the heat sink 600 so that the ink supply path from the ink channel unit 100 to the head chip 400 is not blocked. For example, four types of nozzles 410a, 410b, 410c, 410d for C: cyan, Magenta, Y: yellow, and K: black colors are used for the head chip ( When provided in 400, the ink holes 190 and 690 are also provided for each color. The ink holes 690 provided in the heat sink unit are connected to the ink holes 190 provided in the first channel plate 101, respectively, and the ink holes 190 and 690 are distinguished by colors, so that different inks are provided. Do not mix with each other After the ink stored in the ink tanks 21, 22, 23, and 24 passes through the ink channel unit 100, the ink passes through the ink holes 690 provided in the heat sink 600, and then the first channel plate 101. Passed through the ink hole 190 is provided to the rear surface of the head chip 400, and is supplied to the nozzles 410a, 410b, 410c, 410d by receiving the injection force from the heating element 450.

The protrusion 660 is provided in a rectangular rib shape so as to widen the contact area with the head chip 400 and escape from the ink holes 190 and 690 formed by color, and formed in the first channel plate 101. It is inserted into the protrusion insertion groove 160. In the accompanying drawings, a case where the number of the protrusion 660 and the protrusion insertion groove 160 is illustrated is four, but is not limited thereto. The other end of the protrusion 660 is all connected to the base 640. The material of the protrusion 660 is preferably the same as the material of the base 640. One end of the protrusion 660 independently contacts the rear surface of each of the plurality of head chips 400 arranged in a plurality, but all of the other ends of the protrusion 660 are connected to the base 640. When the temperature of the head chip 400 is higher than the temperature of the base part 640, the base part 640 again conducts heat conducted from the head chip 400 to the protrusion 660. This heat is simultaneously diffused and spread around the base portion 640 having a predetermined heat capacity. Therefore, heat accumulation is prevented while maintaining a uniform temperature distribution of the plurality of head chips 400 arranged in a plurality. In contrast, when the temperature of the head chip 400 is lower than the temperature of the base part 640, heat is conducted from the base part 640 having a uniform temperature distribution to the head chip 400 via the protrusion part 660. do. There is an effect of reducing the temperature increase time of the head chip 400.

In an embodiment, the thermoelectric element 700 includes a peltier element. The thermoelectric element 700 is preferably attached to both ends 650 of the heat sink 600. An adhesive having good thermal conductivity is used for the adhesive layer 760 between the thermoelectric element portion 700 and the heat sink portion 600 at both ends 650. The Peltier element absorbs heat in the heat absorbing portion (not shown) and emits heat in the heat generating portion (not shown) due to the difference in the potential energy of the charge generated when the current flows through the n-type semiconductor and the p-type semiconductor. Say. If the polarity of the power source applied to the Peltier element is reversed, it can be used not only for cooling means but also for heating means. Therefore, in order to raise the temperature of the head chip 400 in a short time, the Peltier element may be used as an auxiliary means for heating the head chip 400 together with the heating element 450.

In one embodiment, the temperature sensor 470 is provided on the head chip seat 140 of the first channel plate 101 attaching the rear surface of the head chip 400. The temperature sensor 470 detects the temperature of the head chip 400 and transmits the temperature to the controller 485. The controller 485 continuously monitors the temperature of the head chip 400 with the temperature sensor 470, determines whether the Peltier device is turned on or off, and the polarity of the voltage applied to the Peltier device. The heat sink 600 is cooled or heated by adjusting. The head chip 400 is prevented from accumulating heat by the cooling action by the Peltier element and the heat dissipation action of the heat sink 600. On the contrary, by the heating action of the Peltier element and the heating element 450, the head chip 400 may be heated up to a predetermined temperature within a short time. The base portion 640 having a predetermined heat capacity makes the temperature distribution uniform throughout the arrangement of the head chips 400 upon heating or cooling by the Peltier element. The heat sink 600 is preferably made of a metallic material including at least one of copper or aluminum to have a predetermined thermal conductivity and heat capacity.

As described above, the array type inkjet head according to the present invention includes a heat sink portion having a predetermined thermal conductivity and a heat capacity and a thermoelectric element portion for heating or cooling the same, and are accumulated in the head chip so that the head chip is not overheated. Dissipate heat to the surroundings, the head chip can be actively cooled when the temperature of the head chip is greater than the predetermined value, on the contrary, if the temperature of the head chip is less than the predetermined value, the head chip can be auxiliaryly heated together with the heating element, The temperature distribution can be controlled uniformly throughout the array of head chips.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and those skilled in the art to which the art belongs can make various modifications and other equivalent embodiments therefrom. Will understand. Therefore, the true technical protection scope of the present invention will be defined by the claims below.

Claims (5)

An ink tank for storing ink; An ink channel unit for forming an ink supply path from said ink tank to a head chip; A back chip fixed to a surface of the ink channel unit to receive ink, and a front head having a plurality of nozzles for ejecting ink, the head chips being arranged in plurality; A temperature in contact with the back surface of each of the head chips, a heat sink unit which is integrally connected to both the protrusions and a heat conduction unit provided with a base unit that conducts heat, and a thermoelectric element unit that heats or cools the heat sink unit. Control unit; Array type inkjet head comprising a. The method of claim 1, The thermoelectric element portion, And an array type inkjet head attached to said base portion. The method of claim 1, The heat sink unit, An array type inkjet head, which is provided as a metallic material including at least one of copper and aluminum. The method of claim 1, The heat sink is provided inside the ink channel unit, The base portion includes a flat plate extending by the array length of the head chip, And the protrusion includes a plurality of rectangular ribs protruding from an upper surface of the flat plate and contacting a rear surface of the head chip. The method according to any one of claims 1 to 4, The temperature control unit, A temperature sensor measuring a temperature of the head chip; A control unit for driving the thermoelectric element unit as a heating source or a cooling source according to the temperature of the head chip; An array type inkjet head further comprising.

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