JP2005081716A - Electrostatic ejection inkjet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic ejection inkjet head capable of correcting the impact position of ink to the pertinent position when it is varied due to variation in the machining accuracy of components or the assembling accuracy, various interference among ink guides, or aging. <P>SOLUTION: The electrostatic inkjet head 10 comprises a head substrate 12, an insulating substrate 16 arranged at a specified interval to the head substrate 12 in order to form an ink channel 22 between and provided at least one through hole 20 opening to a liquid drop receptor, an ink guide 14 arranged on the head substrate 12 such that the forward end part is located substantially in the center of the through hole 20 to project from the through hole 20, a means for supplying ink Q to the ink channel 22, and a ring-like control electrode 18 provided on the insulating substrate 16 to surround the through hole 20 while being divided in the circumferential direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrostatic discharge type ink jet head used in an ink jet recording apparatus that records an image by causing droplets containing particles to fly, and more particularly to an electrostatic discharge type ink jet head that can deflect the flight direction of the droplets.

  Conventionally, as an electrostatic discharge type ink jet recording method, an ink using electrostatic force is used by applying a predetermined voltage to a control electrode of an ink jet head in accordance with image data using ink containing charged fine particle components. There is known a system for controlling the ejection of the ink and recording an image corresponding to the image data on a recording medium. Various ink jet apparatuses using this electrostatic discharge ink jet recording system have been proposed (see, for example, Patent Document 1 and Patent Document 2).

FIG. 6 is a schematic cross-sectional view schematically showing an ink jet head of a conventional ink jet recording apparatus disclosed in Patent Document 1. As shown in FIG.
As shown in FIG. 6, the inkjet head 100 includes an insulating substrate 102 and a head substrate 104 disposed to face the insulating substrate 102. A substrate through hole 102 a is formed in the insulating substrate 102. A control electrode 110 is provided around the substrate through hole 102a. An ink guide 106 is erected on the head substrate 104 so as to be positioned substantially at the center of the substrate through hole 102a. The ink guide 106 has a tip projecting from the substrate through hole 102a, and the ink guide 106 is cut out by a predetermined width along the center line to form an ink guide groove 108.

An ink reservoir 114 is formed by the insulating substrate 102 and the head substrate 104. The control electrode 110 is connected to a signal voltage source 112 that supplies a signal voltage corresponding to an image to be recorded.
Further, a counter electrode 120 is provided on the insulating substrate 102 so as to face the protruding direction side of the tip portion of the ink guide 106. The counter electrode 120 is given a predetermined potential level and holds the recording medium P as a platen.

In the ink jet head 100, the ink reservoir 114 is provided with an ink reflux mechanism (not shown) for circulating the ink Q through an ink supply pipe (not shown) and an ink recovery pipe (not shown). ing.
As the ink Q, a colorant component (charged fine particles) having charging properties dispersed in a colloidal form and suspended in an insulating solvent having a resistivity of 10 ⁸ Ω · cm or more is used.

  In the ink jet head 100 having such a configuration, the ink Q containing particles such as a colorant component moves in the ink guide groove 108 by the capillary phenomenon and accumulates at the tip of the ink guide 106. In this state, when a high voltage pulse is applied from the signal voltage source 112 to the control electrode 110, an ink droplet containing a colorant component jumps out of the ink guide 106 and is pulled by the counter electrode 120 toward the recording medium P. Fly and stick and record images.

FIG. 7 is a schematic cross-sectional view schematically showing an ink jet head of a conventional ink jet recording apparatus disclosed in Patent Document 2. As shown in FIG.
As shown in FIG. 7, the inkjet head 130 includes an insulating support substrate 132 and a substrate 134 that is disposed to face the insulating support substrate 132. An ink reservoir 136 is formed by the insulating support substrate 132 and the substrate 134. The ink reservoir 136 is provided with an ink supply tank (not shown) for supplying the ink Q via a pipe (not shown).

The insulating support substrate 132 is formed with a substrate through hole 132a. First and second control electrodes 140 and 142 are formed on the front and back surfaces of the insulating support substrate 132 so as to surround the periphery of the through hole 132a. A metal platen 120a is disposed facing the surface side of the insulating support substrate 132. The metal platen 120a also serves as a counter electrode, and the recording medium P is held on the metal platen 120a.
A signal voltage source 144 is connected to the first and second control electrodes 140 and 142. A bias voltage source 146 is connected between the second control electrode 142 and the grounded metal platen 120a. As the ink Q, a conductive ink having a conductivity of about 10 ⁵ to 10 ⁹ Ω · cm is used.

  In the inkjet head 130 having such a configuration, the ink Q is supplied from the ink supply tank to the ink reservoir 136, and the ink Q is supplied into the through hole 132a by the hydrostatic pressure. In this state, in addition to the bias voltage, a signal voltage corresponding to the image signal is superimposed and applied between the first and second control electrodes 140 and 142 by the signal voltage source 144. As a result, ink droplets fly from the ink surface in the through hole 132a. The flying ink droplets are accelerated by the bias voltage applied to the metal platen 120a and the first and second control electrodes 140 and 142 and reach the recording medium P to form an image.

In the electrostatic discharge type inkjet heads 100 and 130 shown in FIG. 6 and FIG. 7, components such as the substrate through hole 102 a, the control electrode 110 and the ink guide 106, and the substrate through hole 132 a, the first and second controls. Due to variations in processing accuracy or assembly accuracy of the electrodes 140 and 142, interference between the control electrodes of the respective ejection units, aging, etc., the landing positions of the ink droplets ejected from the ink jet heads 100 and 130 on the recording medium P are changed. There was a problem of variation.
For this reason, in the conventional inkjet head, it is necessary to use expensive parts with higher processing accuracy, and it is necessary to use a head with higher assembly accuracy, resulting in a low yield, resulting in an increase in cost. There was a problem of becoming.

On the other hand, a recording apparatus of a continuous ink jet recording method different from a droplet discharge ink jet recording method such as an electrostatic discharge ink jet head recording method has been proposed (see Patent Document 3).
8 is a schematic cross-sectional view schematically showing a conventional ink jet recording apparatus disclosed in Patent Document 3, and FIG. 9 is a schematic plan view schematically showing an annular heater of the ink jet recording apparatus shown in FIG. It is.
As shown in FIG. 8, in the ink jet recording apparatus, the base 150 and the insulating layer 152 are arranged to face each other with a space therebetween. In this insulating layer 152, a hydrophobic layer 154 is formed on the surface opposite to the base 150. The insulating layer 152 and the hydrophobic layer 154 have nozzle holes 158 that pass through them. An annular heater 160 is formed on the surface of the hydrophobic layer 154 so as to surround the opening of the nozzle hole 158. An ink supply groove 156 is formed along the nozzle hole 158 by the base 150 and the insulating layer 152. The ink supply groove 156 is filled with ink Q, the ink Q is pressurized to atmospheric pressure or higher, and the ink Q is discharged from the opening as a liquid flow (ink flow) 170.

  As shown in FIG. 9, the annular heater 160 has two partition portions (heat generating portions) 160 a and 160 b that respectively surround about ½ of the peripheral edge portion of the opening of the nozzle hole portion 158. The partition portions 160a and 160b are connected to power supply side connection portions 162a and 162b and ground side connection portions 164a and 164b at both ends, respectively. When an electric current is supplied to one of the annular heaters 160 instead of both of the partition portions 160 a and 160 b, the liquid flow 170 is heated and split into a plurality of droplets 172. Also, the heat applied to the liquid flow 170 is asymmetric, which causes the liquid flow 170 to be deflected.

Further, as shown in FIG. 8, an ink exclusion groove 180 is provided to face the hydrophobic layer 154. The ink ejection groove 180 is provided at a position where the deflected droplet 172 reaches the recording medium (not shown) and the undeflected droplet 174 does not reach the recording medium.
In this ink jet recording apparatus, the liquid flow 170 is divided into a plurality of liquid droplets 172 by heat supplied by the annular heater 160 at a position separated from the nozzle hole 158 toward the ink exclusion groove 180 by a predetermined distance. The ink discharge groove 180 prevents the undeflected droplet 174 from reaching the recording medium. Then, when the deflected liquid droplet 172 reaches a recording medium (not shown), the deflected liquid droplet 172 reaches the recording medium and an image is formed.

  The ink jet recording apparatus shown in FIG. 8 and FIG. 9 has a continuous discharge liquid by asymmetrically heating the continuous discharge liquid by two partition (heat generation) portions 160a and 160b surrounding the peripheral portion of the opening of the nozzle hole 158. Since the droplets are formed and deflected at a high repetition frequency, the control of the drive pulses applied to the partition portions 160a and 160b becomes complicated, and stable droplet formation control and accurate There was a problem that droplet deflection control was difficult. In such a continuous ink jet recording method, the deflection of the droplet is for dropping a droplet corresponding to a dot not to be recorded into an ink removal groove such as a catcher on the way, and it is possible to deflect more than a predetermined deflection amount. In other words, it is not necessary to accurately control the amount of deflection of the droplets, and therefore, the amount of deflection is not accurately controlled.

JP-A-10-230608 JP 10-138494 A JP 11-192707 A

  It is an object of the present invention to achieve ink landing even when there are variations in ink landing positions due to variations in processing accuracy of components or assembly accuracy, various interference between ink guides, or deterioration with time. An object of the present invention is to provide an electrostatic discharge type inkjet head capable of correcting the position to an appropriate position.

  In order to solve the above-mentioned problems, the present invention provides an electrostatic that causes at least a droplet including the particle to fly toward a droplet receiver by applying an electrostatic force to ink in which the particle is dispersed in a solvent. A discharge-type inkjet head, which is disposed at a predetermined interval from a head substrate, and forms an ink flow path between the head substrate and is open to the droplet receiver. An insulating substrate having at least one through-hole formed thereon, an ink supply means for supplying the ink to the ink flow path, and the insulating substrate so as to surround the through-hole. The electrostatic discharge type inkjet head is characterized in that it includes a control electrode that performs control, and the control electrode includes a conductor divided into a plurality in the circumferential direction of the through hole.

In the control electrode, it is preferable that at least one of the divided conductors is used to deflect the flying direction of the droplet.
The control electrode includes first and second control electrodes provided on the insulating substrate at a predetermined interval in the droplet flight direction, and at least one of the first and second control electrodes. One of them preferably includes a conductor divided into a plurality in the circumferential direction of the through hole.
Further, one of the first and second control electrodes includes a conductor divided into a plurality in the circumferential direction of the through hole, and is used for deflecting the flying direction of the droplet The other is preferably a discharge control electrode for controlling the discharge of the droplets.

The first control electrode is the deflection electrode provided closer to the droplet receiver than the second control electrode, and the second control electrode is the ejection control electrode. Is preferred.
Further, the first control electrode is provided on the side closer to the droplet receiver than the second control electrode, and is composed of a conductor divided into a plurality in the circumferential direction of the through hole, and the divided It is preferable that at least one of the conductors is a deflection electrode that deflects the droplet flying direction by locally changing the temperature of the ink.
Furthermore, it is preferable that the first control electrode is a heating resistor or a thermoelectric element.

Both of the first and second control electrodes are made of a conductor divided into a plurality in the circumferential direction of the through-hole, and the first control electrode receives the droplet more than the second control electrode. An ejection control electrode provided on a side close to the body for deflecting the flying direction of the droplet and controlling the ejection of the droplet, and the second control electrode deflects the flying direction of the droplet A deflection electrode is preferred.
The second control electrode is preferably a heating resistor or a thermoelectric element.

  The above-described electrostatic discharge type ink jet head according to the present invention, wherein the ink is further disposed on the head substrate so that the tip end portion is positioned substantially at the center of the through hole, and the tip end portion protrudes from the through hole. It is preferable to have a guide.

  According to the electrostatic discharge type ink jet of the present invention, even if the ink landing position varies due to variations in processing accuracy or variations in assembly accuracy, various interference between ink guides, or deterioration with time, The landing position of can be corrected to an appropriate position.

Hereinafter, an electrostatic discharge type inkjet head of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a schematic cross-sectional view schematically showing an electrostatic discharge type ink jet apparatus provided with an electrostatic discharge type ink jet head according to a first embodiment of the present invention, and FIG. FIG. 3 is a schematic plan view showing a configuration of a control electrode of an electrodischarge type inkjet head. In the following, as shown in FIGS. 1 and 2, as an electrostatic discharge type ink jet head, only one discharge portion in which an ink guide is arranged in the center of a through hole of an insulating substrate will be illustrated and described. However, it is needless to say that the present invention is not limited to this, and may have a plurality of ejection portions.

  As shown in FIG. 1, an electrostatic discharge type ink jet head (hereinafter referred to as an ink jet head) 10 according to the present embodiment includes an ink Q containing a color component (for example, toner) such as a charged pigment based on image data. Are ejected as ink droplets D by electrostatic attraction, and an image is recorded on a recording medium (droplet receptor) P. The inkjet head 10 includes a head substrate 12, an ink guide 14, an insulating substrate 16 with a through hole 20, a control electrode 18, an ink flow path 22, a signal voltage source 24, and an ink supply pipe 26. And an ink recovery pipe 28 and an ink reflux means 30. Further, a counter electrode 32 is provided to face the ink jet head 10.

  In the inkjet head 10 shown in FIG. 1, only one ejection part having the ink guide 14 is shown in the center of the through hole 20, but the inkjet head 10 is a multi-channel in which a plurality of ejection parts are arranged. It has a structure. Furthermore, the inkjet head 10 can be applied to image recording in either monochrome or color.

  The head substrate 12 is a substrate on which the ink guide 14 is formed. An insulating substrate 16 is disposed opposite to the head substrate 12 with a predetermined distance. The head substrate 12 and the insulating substrate 16 form an ink flow path 22 for supplying ink Q to the ink guide 14.

  The ink guide 14 is a guide member for discharging the ink Q. The ink guide 14 has a base portion 14a provided on the head substrate 12, and a protruding tip portion 14b provided on the base portion 14a. The base portion 14a has, for example, a truncated cone shape, and the protruding tip portion 14b has, for example, a conical shape. The ink guide 14 is made of an insulating member such as plastic resin or ceramics.

The insulating substrate 16 is made of a ceramic such as Al ₂ O ₃ or ZrO ₂ or a resin such as polyimide. A through hole 20 is formed in the insulating substrate 16, and the ink guide head 14 is disposed such that the protruding tip portion 14 b is the center of the through hole 20.

The control electrode 18 is formed on the insulating substrate 16 so as to surround the through hole 20.
As shown in FIG. 2, the control electrode 18 has a ring shape, and is formed in the circumferential direction of the through hole 20, for example, from first to third electrodes (conductors) 18 a to 18 c divided into three pieces. It will be. The first to third electrodes 18a to 18c are connected to the signal voltage source 24, respectively. In the inkjet head 10, ink droplets can be ejected by selectively applying voltages to the first to third electrodes 18 a to 18 c divided by the signal voltage source 24. The first to third electrodes 18a to 18c are made of, for example, an aluminum thin film wiring, the wiring film thickness is 5 μm, the wiring width is 30 μm, and the wiring interval between the electrodes adjacent to the first to third electrodes 18a to 18c is 5 μm. It is. The material of the first to third electrodes 18a to 18c is not limited to aluminum and may be other materials, for example, aluminum alloy, copper, or copper alloy. Good.

  In the present embodiment, the number of electrodes constituting the control electrode 18 is not particularly limited, but in order to correct the flying direction of the ink droplet D by correcting the number of electrodes, the number of electrodes is three. The above is preferable.

As shown in FIG. 1, the insulating film 19 is formed on the insulating substrate 16 so as to cover the control electrode 18 formed on the insulating substrate 16. The insulating film 19 is a laminated film of an insulating layer made of a fluororesin such as Cytop ^™ and having a thickness of 0.5 μm and an inorganic insulating layer formed on the insulating layer. This inorganic insulating layer is made of, for example, SiO ₂ . In the insulating film 19, a layer using a silane coupling agent having a fluorine group that forms an adsorption monolayer on the inorganic insulating layer may be formed.

The ink flow path 22 supplies the ink Q to the ink guide 14.
The signal voltage source 24 is connected to the first to third electrodes 18a to 18c. The signal voltage source 24 applies a bias voltage of 1.5 kV to all of the first to third electrodes 18a to 18c, for example, when the charge of the fine particles in the ink Q is positive, and applies to the image data. Based on this, a pulse voltage (S _{1 to} S ₃ ) of, for example, 600 V is selectively applied to at least one of the first to third electrodes 18 a to 18 c in a superimposed manner.
When applying a reverse bias voltage (for example, -1.5 kV) to the recording medium P side or charging, it is not necessary to apply a bias voltage to the signal voltage source 24.

  The ink reflux means 30 supplies the ink Q to the ink flow path 22, collects it, and causes the ink Q to reflux, and also serves as the ink supply means. The ink reflux means 30 is connected to an ink supply pipe 26 and an ink recovery pipe 28 connected to the ink flow path 22. The ink reflux means 30 circulates the ink Q at a predetermined speed in the direction from the ink supply pipe 26 side to the ink recovery pipe 28 side during recording. In addition, although not shown, the ink reflux means 30 includes a pump, an ink tank, and the like. The ink Q sent out from the ink reflux means 30 is supplied to the ink flow path 22 through the ink supply pipe 26, a part is ejected from the ink guide 14, and the ink Q is discharged from the ink flow path 22 through the ink recovery pipe 28. It is recovered by the reflux means 30.

The ink Q used in this embodiment is, for example, a positively charged color component (hereinafter also referred to as charged fine particles) dispersed in a colloidal form in an insulating solvent together with a charge control agent or a binder and suspended. The voltage applied to the control electrode 18 has the same polarity as the charged fine particles. This insulating solvent preferably has a resistivity of 10 ⁸ Ω · cm or more.

In the present embodiment, it is preferable to form a metal thin film on the protruding tip 14b of the ink guide 14. By this metal thin film, the concentration of the electric field on the protruding tip 14b is increased, and the voltage level of the bias voltage or pulse voltage applied to the control electrode 18 for causing the ink droplet D to fly can be lowered.
Further, the shape of the ink guide 14 is particularly limited as long as the ink Q, in particular, the charged fine particles in the ink Q can be concentrated to the protruding tip 14b through the through hole 20 of the insulating substrate 16. is not. For example, the protruding tip portion 14b does not have to be a protruding shape, can be changed as appropriate, and may have the shape of a conventionally known ink guide disclosed in the above-mentioned Patent Document 1.

  The counter electrode 32 is disposed at a position facing the protruding tip portion 14b of the ink guide 14, and is grounded. The recording medium P is supported on the surface of the counter electrode 32 on the ink jet head 10 side, and the counter electrode 32 also has a function as a platen of the recording medium P.

Next, the operation of the inkjet head 10 of this embodiment will be described.
In the ink jet head 10 shown in FIG. 1, ink Q containing color components (charged fine particles) having the same polarity as the voltage applied to the control electrode 18, for example, positive (+), is charged by the ink reflux means 30 during recording. The ink flow path 22 is moved from the ink supply pipe 26 toward the ink recovery pipe 28. At this time, the recording medium P is electrostatically attracted to the counter electrode 32.

  Here, when the pulse voltage is not applied to any of the first to third electrodes 18a to 18c of the control electrode 18, or when the applied pulse voltage is at a low voltage level (0V), the control is performed. The voltage (potential difference) between the electrode 18 and the counter electrode 32 (recording medium P) is, for example, 1.5 kV corresponding to the bias voltage. The electric field strength in the vicinity of the protruding tip portion 14b of the ink guide 14 is low, and the ink Q is not ejected as the ink droplet D from the protruding tip portion 14b of the ink guide 14.

  However, at this time, a part of the ink Q in the ink chamber 22, in particular, the charged fine particles contained in the ink Q pass through the through hole 20 of the insulating substrate 16 due to a migration phenomenon or a capillary phenomenon, and the ink guide 14. The ink meniscus M is formed in the vicinity of the protruding tip portion 14b. As described above, the ink meniscus M is formed in the vicinity of the protruding tip portion 14b, whereby the ink Q is supplied to the protruding tip portion 14b.

On the other hand, when a pulse voltage of, for example, 600 V is applied to all of the first to third electrodes 18a to 18c of the control electrode 18 as a signal voltage based on image data, the control electrode 18 and the counter electrode 32 (recording medium) The voltage (potential difference) with respect to P) is, for example, 1.5 kV by superimposing a bias voltage of 1.5 kV and a pulse voltage of 600 V, and the electric field strength in the vicinity of the protruding tip 14 b of the ink guide 14 is Get higher.
At this time, the ink Q rising along the ink guide 14 and reaching the protruding tip 14b, in particular, the charged fine particles concentrated in the ink Q, is charged from the protruding tip 14b of the ink guide 14 by electrostatic force. The ink droplets D containing fine particles are ejected toward the counter electrode 32 (recording medium P) and adhere to the recording medium P.

  That is, in the present embodiment, a voltage of, for example, 1.5 kV is always applied as a bias voltage from the signal voltage source 24 to the control electrode 18. Further, from the signal voltage source 24, for example, a pulse voltage of 600 V is superimposed as a control voltage as a signal voltage corresponding to the image signal. That is, when the control voltage is 0 V (OFF state) and the voltage of the control electrode 14 is 1.5 kV, the ink droplet D of the ink Q does not fly, the control voltage is 600 V (ON state), and the control electrode 18 When the voltage becomes 2.1 kV, the ink droplet D having a predetermined size flies from the protruding tip portion 14 b of the ink guide 14. The flying ink droplets D are attracted to the counter electrode 32 by an electric field generated between the control electrode 18 and the counter electrode 32, and land on a predetermined position of the recording medium P to record an image. In this way, the ink droplets D are landed and an image is formed. However, variations in processing accuracy of components constituting the inkjet head 10 or variations in assembly accuracy of the inkjet head 10, various types of ink guides 14. The ink droplet D does not necessarily land at a predetermined position due to the interference of the ink jet or the deterioration of the inkjet head 10 over time.

  Even in such a case, the ink jet head 10 according to the present embodiment increases or decreases the pulse voltage applied to any one of the first to third electrodes 18a to 18c of the control electrode 18 so that the ink droplet D The discharge direction can be deflected. For this reason, in this embodiment, initial failure due to variations in the processing accuracy of the components of the inkjet head 10 or variations in the assembly accuracy of the inkjet head 10, various interferences between the ink guides, or deterioration of the inkjet head 10 over time. Thus, even if the landing position of the ink droplet D deviates from a predetermined position and is not an appropriate position, the landing position can be corrected.

  In this embodiment, since the charged fine particles contained in the ink droplet D are positively charged, if the applied pulse voltage is increased, a repulsive force acts on the charged fine particles, and the charged fine particles are applied with a pulse voltage. The ink droplet D is deflected in the direction opposite to the applied electrode. Further, the ink droplet D may be deflected in a predetermined direction by adjusting the level of the pulse voltage applied to the three first to third electrodes 18a to 18c. Thereby, the landing position of the ink droplet D can be corrected, and the ink droplet D can be landed at an appropriate position.

  As described above, in the first embodiment of the present invention, the control electrode 18 (discharge control electrode) is divided into, for example, the first to third electrodes and can be selectively operated. Since it is possible, the shape of the ink meniscus formed in the through hole 20 and the ink guide 14 can be asymmetrical, and the ejection direction can be deflected. For this reason, by using the deflection in the ejection direction, it is possible to correct in advance the variation in the ejection direction due to various interferences such as electrostatic or fluid received from the surrounding ejection sites.

Next, a second embodiment of the present invention will be described.
FIG. 3 is a schematic cross-sectional view schematically showing an electrostatic discharge type ink jet apparatus provided with an electrostatic discharge type ink jet head according to a second embodiment of the present invention. FIG. FIG. 5 is a schematic plan view showing a configuration of a deflection electrode of an electrodischarge type ink jet head, and FIG. 5 is a schematic plan view showing a control electrode of the electrostatic discharge type ink jet head of this embodiment. In the present embodiment, the same components as those in the first embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, the electrostatic discharge type inkjet head 11 of the present embodiment is different from the inkjet head 10 of the first embodiment in that the control electrode 18 (see FIG. 1) of the inkjet head 10 of the first embodiment. Reference point) is different in that the deflection electrode 40 is provided as the second control electrode and the arrangement position and shape of the control electrode 21 (first control electrode) are different. Since the configuration is the same as that of the inkjet head 10 of the first embodiment, detailed description thereof is omitted.

In the inkjet head 11 of the present embodiment, as shown in FIG. 4, the deflection electrode 40 has a ring shape and is provided so as to surround the periphery of the through hole 20. It is divided into three pieces. The deflection electrode 40 includes first to third electrodes (hereinafter referred to as heaters) 40a to 40c that function as heaters (heating resistors). Each of the first to third heaters 40a to 40c is made of, for example, TaSiO ₂ thin film wiring, and has a resistance value of about 100Ω. Each of the first to third heaters 40a to 40c has, for example, a wiring thickness of 0.8 μm, a wiring width of 5 μm, and a wiring interval between adjacent electrodes of 5 μm. The heater material of each of the heaters 40a to 40c of the deflection electrode 40 may be TaSiO ₂ , Ta single layer, TaN or the like, as long as it has a required resistance value or appropriateness to the fluid to be used. Anything Moreover, what is necessary is just to adjust suitably the resistance value of each heater 40a-40c according to the heater material or fluid to be used.

Each of the first to third heaters 40 a to 40 c is connected to a deflection control power source 42. The deflection control power source 42 is capable of switching with a capacity of, for example, a voltage of 2 V and a current of about 20 mA, and applies voltages (V _{1 to} V ₃ ) to the _first to third heaters 40 a to 40 c. Application can generate heat. As a result, each of the first to third heaters 40a to 40c generates heat, the ink Q filled in the through hole 20 is locally heated, and the shape of the meniscus M is made asymmetric.

  As shown in FIG. 5, the control electrode 21 has a ring shape and is connected to the signal voltage source 25. The signal voltage source 25 can apply a pulse signal having a pulse voltage of, for example, 600 V to the control electrode 21, and can apply a voltage of 1.5 kV, for example, to the control electrode 21 as a bias voltage. .

  In the present embodiment, three divided first to third heaters 40a to 40c are provided so as to surround the periphery of the through hole 20, and these first to third heaters 40a to 40c are used. Thus, the surface tension of the ink Q can be locally reduced, the shape of the meniscus M can be changed, and the ejection direction of the ink droplet D can be deflected. In this case, the flying direction of the ink droplet D is deflected in the direction in which the heat generation amount is larger among the first to third heaters 40a to 40c.

  In the second embodiment of the present invention, the discharge control function of the ink droplet D and the deflection function of the ink droplet D provided in the control electrode 18 of the first embodiment are separated, and each has a discharge control function. The control electrode 21 and the deflection electrode 40 having a deflection function are provided separately. For this reason, in the first embodiment, since deflection control is performed using the control electrode 18 to which a high voltage is applied, the electrical circuit (control circuit) for deflection control also requires a very high voltage. In the second embodiment, since the deflection electrode 40 and the control electrode 21 are provided separately, the surface tension of the ink liquid is partially changed by partial heating by the deflection electrode 40, thereby changing the ejection direction. Since it can be controlled, an electric circuit (control circuit) used for deflection can be constituted by a low voltage circuit. For this reason, in the second embodiment, the same function can be realized at a lower cost than in the first embodiment.

Next, the operation of the inkjet head 11 of this embodiment will be described.
First, as in the first embodiment, the signal voltage source 25 applies a bias voltage to the control electrode 21 and further superimposes a pulse voltage based on the image data to eject the ink droplet D. In this case, it is determined whether or not the landing position of the ink droplet D is appropriate. When the landing position of the ink droplet D is not appropriate, the deflection control power supply 42 generates heat by causing any one of the first to third heaters 40a to 40c to generate heat, thereby locally reducing the surface tension of the ink Q. The ejection direction of the droplet D is deflected so that the landing position is appropriate. Thereby, the landing position of the ink droplet D can be corrected to an appropriate position.

  As described above, in this embodiment, the ink Q is locally heated by the first to third heaters 40a to 40c to locally reduce the surface tension of the ink Q, whereby the ink droplets D fly. The direction can be deflected. In this embodiment, since the first to third heaters 40a to 40c are used for heating the ink Q, the deflection control power source 42 is the signal voltage source 24 of the first embodiment (see FIG. 1). As compared with the case, a low voltage can be used. For this reason, in this embodiment, the same effect as that of the first embodiment can be obtained, and the cost can be reduced as compared with the inkjet head 10 (see FIG. 1) of the first embodiment. it can.

In the present embodiment, the deflection electrode 40 is composed of the first to third heaters 40a to 40c that function as heaters (heating resistors). However, the present invention is not limited to this, and the ink Any device that can deflect the ejection direction of the droplet D may be used. As the deflection electrode 40, in addition to the heater, for example, an electrode that can locally change the temperature of the ink Q by cooling is used. In this case, examples of cooling include thermoelectric elements such as Peltier elements.
In the present embodiment, the number of heaters or Peltier elements constituting the deflection electrode 40 is not particularly limited, but in order to correct the flying direction of the ink droplet D, the number of heaters or Peltier elements is It is preferable that the number is 3 or more.

Further, in this embodiment, the arrangement of the control electrode 21 and the deflection electrode 40 is exchanged, and the configuration of the control electrode 21 is the same as that of the control electrode 18 of the first embodiment, so that the deflection by the deflection electrode 40 is reduced. The discharge control (fast deflection) by the control electrode 21 may be used in combination.
Further, the control electrode 21 of the present embodiment can be configured similarly to the control electrode 18 of the first embodiment. With this configuration, the flying direction of the ink droplet D can be corrected by the control electrode 21, so that the landing position of the ink droplet D can be corrected with higher accuracy by the synergistic effect with the deflection electrode 40.
Furthermore, the configuration of the deflection electrode 40 and the control electrode 21 may be the configuration of the control electrode 18 of the first embodiment. In this case, the flying direction is corrected by the two control electrodes, and the flying direction of the ink droplet D can be corrected with higher accuracy than in the first embodiment.
The control electrode 21 may be a multilayer structure electrode in any case. Furthermore, in addition to the control electrode 21 and the deflection electrode 40, an electrode for stabilizing meniscus formation may be provided.

  Further, the electrostatic discharge type inkjet head of any of the above-described embodiments is not limited to the one that discharges ink containing a charged color component, and any liquid discharge head that discharges a liquid containing charged particles. There is no particular limitation. For example, an electrostatic discharge type inkjet head can be applied to a coating apparatus that uses polyimide as charged particles and discharges droplets containing the charged particles to apply an object.

  As described above, the electrostatic discharge type inkjet head according to the embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described various embodiments, and various improvements and modifications can be made without departing from the gist of the present invention. Of course, changes may be made.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view schematically showing an electrostatic discharge type inkjet apparatus including an electrostatic discharge type inkjet head according to a first embodiment of the present invention. FIG. 2 is a schematic plan view illustrating a configuration of a control electrode of the electrostatic discharge type inkjet head according to the present embodiment. It is a typical sectional view showing typically an electrostatic discharge type ink jet device provided with an electrostatic discharge type ink jet head concerning the 2nd example of the present invention. FIG. 2 is a schematic plan view illustrating a configuration of a deflection electrode of the electrostatic discharge type inkjet head according to the present embodiment. FIG. 2 is a schematic plan view showing a control electrode of the electrostatic discharge type inkjet head of the present embodiment. It is typical sectional drawing which shows typically the inkjet head of the conventional inkjet recording device. It is typical sectional drawing which shows typically the inkjet head of the conventional inkjet recording device. It is typical sectional drawing which shows the conventional inkjet recording device typically. FIG. 9 is a schematic plan view schematically showing a ring heater of the ink jet recording apparatus shown in FIG. 8.

Explanation of symbols

10, 11 Electrostatic discharge type inkjet head 12, 104 Head substrate 14, 106 Ink guide 16, 102 Insulating substrate 18, 21, 110 Control electrode 19 Insulating layer 20 Through hole 22 Ink flow path 24, 25, 112, 144 Signal Voltage source 26 Ink supply pipe 28 Ink recovery pipe 30 Ink reflux means 32, 120 Counter electrode 40 Deflection electrode 42 Deflection control power supply 100, 130 Inkjet head 102a Substrate through hole 114, 136 Ink reservoir 132 Insulating support substrate 132a Through hole 140 First 1 control electrode 142 second control electrode 146 bias voltage source 150 base 152 insulating layer 154 hydrophobic layer 158 nozzle hole 160 annular heater D ink droplet P recording medium Q ink

Claims (10)

An electrostatic discharge type inkjet head that causes a droplet including at least the particle to fly toward a droplet receptor by applying an electrostatic force to ink in which the particle is dispersed in a solvent,
A head substrate;
An insulating property that is disposed with a predetermined distance from the head substrate, forms an ink flow path between the head substrate, and has at least one through hole opened to the droplet receiver. A substrate,
Ink supply means for supplying the ink to the ink flow path;
A control electrode that is provided on the insulating substrate so as to surround the through-hole, and controls discharge of the droplets;
The electrostatic discharge type inkjet head, wherein the control electrode includes a conductor divided into a plurality in the circumferential direction of the through hole.   The electrostatic discharge type inkjet head according to claim 1, wherein at least one of the divided conductors is used for deflecting a flying direction of the droplet. The control electrode has first and second control electrodes provided on the insulating substrate at a predetermined interval in the droplet flight direction,
2. The electrostatic discharge type inkjet head according to claim 1, wherein at least one of the first and second control electrodes includes a conductor divided into a plurality in the circumferential direction of the through hole.   One of the first and second control electrodes includes a conductor divided into a plurality in the circumferential direction of the through hole, and is a deflection electrode used for deflecting the flight direction of the droplet. 4. The electrostatic discharge type inkjet head according to claim 3, wherein the other one is a discharge control electrode for performing discharge control of the droplet.   The first control electrode is the deflection electrode provided closer to the droplet receiver than the second control electrode, and the second control electrode is the ejection control electrode. Item 5. The electrostatic discharge type inkjet head according to Item 4.   The first control electrode is provided on a side closer to the droplet receiver than the second control electrode, and includes a conductor divided into a plurality in the circumferential direction of the through hole. The electrostatic discharge type inkjet head according to claim 3, wherein at least one of the electrodes is a deflection electrode that locally changes a temperature of the ink to deflect a flying direction of the droplet.   The electrostatic discharge inkjet head according to claim 3, wherein the first control electrode is a heating resistor or a thermoelectric element.   Both of the first and second control electrodes are made of a conductor divided into a plurality in the circumferential direction of the through-hole, and the first control electrode receives the droplet more than the second control electrode. An ejection control electrode provided on a side close to the body for deflecting the flying direction of the droplet and controlling the ejection of the droplet, and the second control electrode deflects the flying direction of the droplet The electrostatic discharge type inkjet head according to claim 3, wherein the electrostatic discharge type inkjet head is a deflection electrode.   The electrostatic discharge inkjet head according to claim 8, wherein the second control electrode is a heating resistor or a thermoelectric element. The electrostatic discharge type inkjet head according to any one of claims 1 to 9,
The electrostatic discharge type inkjet head further comprising an ink guide that is disposed on the head substrate so that a front end portion is positioned at a substantially center of the through hole, and the front end portion protrudes from the through hole.

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