CN100436135C - Electrostatic actuator and manufacturing method thereof, droplet discharging head and manufacturing method thereof - Google Patents

Abstract

An electrostatic actuator includes: a diaphragm (12) constituting one electrode; and an electrode substrate (3) on which an opposed electrode (17) opposite to the diaphragm (12) has been formed with a gap (20), in which the opposed electrode (17) is formed in a grooved portion (19), having a rectangular shape in plan view, formed on the electrode substrate (3) in a plurality of steps such that the gap (20) gradually increases stepwise toward a center part in a long edge direction of the grooved portion (19).

Description

Electrostatic actuator and manufacture method thereof, droplet discharging head and manufacture method thereof

Technical field

The present invention relates to a kind of electrostatic actuator with and the droplet discharging head of manufacture method, application electrostatic actuator with and manufacture method, possess droplet discharging head the drop liquid discharging device, possess the equipment of electrostatic actuator.

Background technology

Ink-jet recording apparatus, but it is minimum to have a noise in flying print, when record, and the free degree of printing ink is very high, can use cheap many advantages such as common paper.In recent years, even if in ink-jet recording apparatus, also be that the ink-jet recording apparatus of so-called drop on demand ink jet (inkondemand) mode becomes main flow, it is ejection droplet of ink when needs write down only.This printing ink is opened the ink-jet recording apparatus of request mode, exist do not need to write down the advantage of recovery etc. of unwanted droplet of ink.

In the ink-jet recording apparatus of this drop on demand ink jet mode, there is the ink-jet recording apparatus of so-called static type of drive, as the method that makes the droplet of ink ejection, it utilizes electrostatic force in driving mechanism.And, there is the ink-jet recording apparatus of so-called Piezoelectric Driving mode, it utilizes piezoelectric element in driving mechanism; Or the ink-jet recording apparatus of so-called bubble type ink-jet (bubble jet, login trade mark) mode etc., it utilizes heater element etc.

In the ink-jet recording apparatus of above-mentioned static type of drive,, make it deflection thereby draw oscillating plate at the opposite electrode side draught by making oscillating plate and opposite electrode opposed charged with it.Generally will be like this by making 2 kinds of objects charged, thereby the mechanism that drives is called electrostatic actuator.In the device of the electrostatic actuator of using ink-jet recording apparatus etc., generally to go up and form many grooves at the substrate of forming by gas etc. (electrode base board), the opposite electrode of portion's formation within it makes between oscillating plate and the opposite electrode has the gap.

In the nearest ink-jet recording apparatus, promoted densification, along with the width of this densification oscillating plate has diminished.Therefore, the problem of generation is that the excluded volume of printing ink (area of plane * gap width of oscillating plate) diminishes, and along with densification, the spray volume of printing ink tails off.

In order to eliminate such problem, consider gap enlargement is guaranteed the displaced volume of printing ink, but, then have to be used in the big problem of driving voltage change that drives oscillating plate if with the gap enlargement between oscillating plate and the opposite electrode.

In electrostatic actuator in the past, the groove of elongated shape that forms opposite electrode is stepped at width, is 2 more than the kind by making gap width between opposite electrode and the oscillating plate, thereby makes driving voltage reduce (for example with reference to patent documentation 1).

In addition, according to making the groove that forms opposite electrode form stepped at width, central portion at opposite electrode and oscillating plate, the mode of gap enlargement, relax the rapid bending of the central portion of oscillating plate, the stress that prevents the oscillating plate central portion becomes big, makes the durability of ink gun improve (for example with reference to patent documentation 2).

But, in the above-mentioned electrostatic actuator and ink gun in the past, owing to make the groove of the elongated shape that forms opposite electrode form stepped at width, and become big in the gap of the central portion of opposite electrode and oscillating plate, therefore the problem that produces is, is used to make the oscillating plate of flexural deformation maximum less to reduce at the driving voltage that the length direction central portion docks with opposite electrode.

Patent documentation 1: the spy opens 2000-318155 communique (Fig. 2, Fig. 4, Fig. 5)

Patent documentation 2: the spy opens flat 11-291482 communique (Fig. 4～Fig. 7)

Summary of the invention

The present invention is used to address the above problem, even its purpose is to provide a kind of displacement of side's electrode of formation electrostatic actuator very big, also the electrostatic actuator that can drive with low voltage with and manufacture method.Simultaneously, its purpose droplet discharging head of being to provide a kind of this electrostatic actuator of application with and manufacture method, possess the drop liquid discharging device of this droplet discharging head and possess the equipment of above-mentioned electrostatic actuator.

Electrostatic actuator of the present invention, possess: constitute the oscillating plate of side's electrode and form and this oscillating plate across the opposed opposite electrode in gap, electrode base board, above-mentioned opposite electrode, its formed flat shape on above-mentioned electrode base board is roughly OBL slot part formation, and form along with the central portion to the long side direction of above-mentioned slot part, above-mentioned gap becomes big a plurality of sections (stepped).According to this electrostatic actuator, be that stair-stepping situation is compared with making slot part in minor face (width) direction, can produce bigger moment for oscillating plate, even the displacement of oscillating plate is very big, its driving voltage is effectively reduced.In addition, because at the central portion of slot part, gap length is the longest, length is the shortest in the tip-clearance of slot part, so oscillating plate begins distortion from both ends, and driving voltage is effectively reduced.

The section of each of preferred above-mentioned opposite electrode section is poor, along with the long side direction end from above-mentioned slot part diminishes to central portion.

If it is poor to form the section of stair-stepping slot part, form according to the mode that diminishes to central portion along with end from slot part, then in the shortest part of the tip-clearance of slot part length, so that the driving voltage that oscillating plate docks with opposite electrode, oscillating plate integral body is docked with opposite electrode, just can drive with very low driving voltage.Therefore, under the situation in the pressure oscillation mechanism of the balancing gate pit that this driver is applied to droplet discharging head, can guarantee enough drop jetting amount with very low driving voltage.

In addition, preferably in each section boundary portion of above-mentioned opposite electrode, adjacent section forms according to the mode that enters into the other side's side or adjacent section epimere end, form at least the section difference transfer portion that forms by 1 recess or, form section poor transfer portion that forms by 1 protuberance at least in the hypomere end of above-mentioned adjacent section.

According to these electrostatic actuators, attract the electrostatic attraction of oscillating plate in the segment difference section, with in the butt joint of epimere portion, produce in the butt joint of section difference boundary portion with in the order of the butt joint of hypomere portion, by the butt joint of leading portion part, making next, the electric field of the part of butt joint progressively uprises.Like this, just can utilize the apply voltage corresponding, carry out docking of oscillating plate and opposite electrode with very narrow gap.

Preferably with the width of the long side direction quadrature of above-mentioned opposite electrode, along with the long side direction end from above-mentioned slot part broadens by each each section face successively to central portion.Thus, be because, therefore easily bring out the lasting butt joint of the section portion that opposite electrode is adjacent on oscillating plate owing in wideer scope, act on electrostatic attraction.

Preferred above-mentioned electrode base board is made of pyrex.If according to like this,,, therefore also can prevent the dislocation that causes because of thermal conductance because their expansion rate differs widely even then electrode base board engages with silicon system oscillating plate.And preferred above-mentioned opposite electrode is made of ITO.Because ITO is transparent, when therefore existing in the anodic bonding of electrode base board and silicon system oscillating plate, can confirm the advantage of discharge condition.

Droplet discharging head of the present invention possesses the described electrostatic actuator of above-mentioned each technical scheme, and above-mentioned oscillating plate constitutes the wall that drop is kept the balancing gate pit that makes it to spray.

Droplet ejection apparatus of the present invention carries above-mentioned droplet discharging head.

Equipment of the present invention possesses the described electrostatic actuator of above-mentioned each technical scheme.

In these droplet discharging heads, drop liquid discharging device and equipment, the action that can carry out that drop shoots out etc. with low-voltage, but and the miniaturization of implement device.

The manufacture method of electrostatic actuator of the present invention has: groove forms operation, and it implements repeatedly etching on electrode base board, forms flat shape and is oblong-shaped roughly, along with the stair-stepping slot part that deepens to the central portion of its long side direction; Electrode forming process, it with the electrode material film forming, forms the opposite electrode with section poor shape corresponding with the section difference of this slot part in the inside of above-mentioned slot part; With the joint operation, electrode base board after its above-mentioned each operation that will be through with, engages, and make the oscillating plate formation predetermined face of above-mentioned opposite electrode and above-mentioned oscillating plate or aforesaid substrate opposed with oscillating plate that constitutes side's electrode or the substrate that forms oscillating plate afterwards.According to this method, can access electrostatic actuator with above-mentioned characteristic.

In addition, the section difference of each of preferred above-mentioned slot part section is, along with the long side direction end from above-mentioned slot part diminishes to central portion.Like this, the section difference of opposite electrode is also corresponding with it, can be along with diminishing to central portion from the long side direction end.

And, preferably with the width of the long side direction quadrature of above-mentioned slot part, along with the long side direction end from above-mentioned slot part broadens by each each section face successively to central portion.Like this, the width of opposite electrode is also corresponding to it becoming big from the long side direction end to central portion.

Further, preferably the smooth thickness of the opposite electrode that forms in the inside of above-mentioned slot part is thicker than any section difference of above-mentioned slot part.In case form opposite electrode according to such film forming, just can prevent the interruption of opposite electrode in the boundary portion of section difference.

Form in the operation at above-mentioned groove,, enter into the mode of the other side's side mutually, form groove according to adjacent section preferably in each section boundary portion of above-mentioned slot part.

And, form in the operation at above-mentioned groove, preferably in each section boundary portion of above-mentioned slot part, form at least the section difference transfer portion that forms by 1 recess in the epimere end of adjacent section or forms section poor transfer portion that forms by 1 protuberance at least in above-mentioned adjacent hypomere end.

The manufacture method of droplet discharging head of the present invention is used the manufacture method of the described electrostatic actuator of above-mentioned each technical scheme, constitutes the pressure oscillation mechanism that keeps the balancing gate pit that drop makes it to spray.According to this method, just can access the high droplet discharging head of very low driving voltage and driveability.

Description of drawings

Fig. 1 is the electrostatic actuator of expression the present invention the 1st embodiment and the profile of droplet discharging head.

Fig. 2 is the amplification profile of part of slot part, opposite electrode and the oscillating plate of presentation graphs 1.

Fig. 3 is for making the driving voltage that oscillating plate docks with opposite electrode and the key diagram of gap length about being used to drive.

Fig. 4 is for about being used to drive the key diagram that makes the driving voltage that oscillating plate docks with opposite electrode.

Fig. 5 is the section process chart of manufacture method one example of the droplet discharging head of expression the 1st embodiment.

Fig. 6 is the process chart after Fig. 5.

Fig. 7 is the process chart after Fig. 6.

Fig. 8 is the profile of the electrostatic actuator of expression the present invention the 2nd embodiment.

Fig. 9 is the 1st upward view that constitutes of segment difference section of the opposite electrode of key diagram 8.

Figure 10 is the 2nd upward view that constitutes of segment difference section of the opposite electrode of key diagram 8.

Figure 11 is the 3rd upward view that constitutes of segment difference section of the opposite electrode of key diagram 8.

Figure 12 is the stereogram of the drop liquid discharging device of expression the present invention the 3rd embodiment.

Among the figure: 1-droplet discharging head, 2-hole substrate, 3, the 3A-electrode base board, 4-nozzle plate, 6-the 1st nozzle bore, 7-the 2nd nozzle bore, the 8-nozzle, the 10-drop shoots out face, the 11-composition surface, 12, the 12A-oscillating plate, 13-sprays chamber, 14-storeroom, the 15-hole, 16-dielectric film, 17, the 17A-opposite electrode, 18-inking hole, 19,19A-slot part, 19a-connectivity slot, 20, the 20A-gap, 21-electrode taking-up portion, the 22-encapsulant, 24-boundary portion (perhaps section difference transfer portion), 25, the 25A-drive circuit.

The specific embodiment

The 1st embodiment

Fig. 1 is the sectional side elevation of the droplet discharging head of expression the present invention the 1st embodiment.Among Fig. 1, represent electrostatic actuator of the present invention is applied to the example of droplet discharging head, this droplet discharging head is the face injection types of static type of drive.

The droplet discharging head 1 of this 1st embodiment is mainly by constituting by hole substrate 2, electrode base board 3 and nozzle plate 4 are engaged.

Nozzle plate 4 is made up of silicon etc., forms nozzle 8, and it has: the 1st nozzle bore 6 for example cylindraceous and be communicated with the 1st nozzle bore 6, and than big the 2nd nozzle bore 7 cylindraceous in the 1st nozzle bore 6 apertures.The 1st nozzle bore 6 forms according to the mode of shooing out face 10 (with the opposing face on the composition surface 11 of hole substrate 2) upper shed at drop, and the 2nd nozzle bore 7 is according to forming in the mode with composition surface 11 upper sheds of hole substrate 2.

In addition, on nozzle plate 4, become and be used to make the recess that shoots out the spout 15 that chamber 13 is communicated with storeroom 14 shown below.A plurality of relatively ejections chamber 13 forms this spout 15 respectively one by one.And spout 15 also can form in nozzle plate 4 sides of hole substrate 2.

Hole substrate 2 is made up of for example monocrystalline silicon, forms a plurality of recesses that become ejection chamber 13.Diapire as 1 wall that constitutes ejection chamber 13 becomes the oscillating plate 12 with toughness.And a plurality of ejections chamber 13 is, forms side by side to paper is inboard parallel from the paper front side of Fig. 1.In addition in hole substrate 2, be formed for supplying with the recess of storeroom 14 of the drop of printing ink etc. to each ejection chamber 13.In droplet discharging head 1 as shown in Figure 1, storeroom 14 is formed by single recess.

Further, form the dielectric film of forming by silica or aluminium oxide etc. 16 at the face of a side of the bonding electrodes substrate 3 of hole substrate 2.This dielectric film 16 prevents insulation breakdown or the short circuit of droplet discharging head 1 when driving.And,, form the diaphragm of forming by silica etc. of anti-drop the (not shown) in a side that engages with nozzle plate 4 of hole substrate 2.This diaphragm of anti-the drop prevents that drop because of ejection chamber 13 or storeroom 14 inside is with 2 etchings of hole substrate.

In oscillating plate 12 sides of hole substrate 2, engage the electrode base board of for example forming 3 by borosilicate glass.A plurality of slot parts 19 form the oblong-shaped with minor face and long limit on the composition surface of this electrode base board 3, this slot part 19, the central portion that forms length direction is the darkest, to both ends shoal stepped.And, at this so-called slot part 19, be meant part in the face of oscillating plate 12, be different from the connectivity slot 19a that is communicated with electrode taking-up portion 21.And,, form oscillating plate 12 opposed a plurality of opposite electrodes 17 with the electrode that constitutes a side in the inside of slot part 19.This opposite electrode 17 is by splash ITO (Indium Tin Oxide) and forming for example.And the space between slot part 19 and the opposite electrode 17 becomes gap (gap) 20.Describe in detail about slot part 19 and opposite electrode 17 back.

Further, on electrode base board 3, form the inking hole 18 that is communicated with storeroom 14.This inking hole 18 is connected with the hole that is provided with at the diapire of storeroom 14, is used for from the outside being provided with to the drop of storeroom 14 supply printing ink etc.In addition, immerse gap 20 in order to prevent steam etc., and the space sealing that will form by gap 20 and connectivity slot 19a by encapsulant 22.

At this, describe at the action of droplet discharging head shown in Figure 11.Be connected with drive circuit 25 in hole substrate 2 and each opposite electrode (being also referred to as single electrode) 17.And opposite electrode 17 is connected with drive circuit 25, is to carry out in the part of electrode taking-up portion 21.If apply pulse voltage by drive circuit 25 between hole substrate 2 and electrode 17, then oscillating plate 12 is to opposite electrode 17 side bendings, and the drop of the printing ink that keeps in the inside of storeroom 14 etc. flows into to ejection chamber 13.In addition, in this 1st embodiment, when oscillating plate 12 bendings, opposite electrode 17 is connected with oscillating plate 12 (via dielectric film 16).And if the voltage that does not apply between hole substrate 2 and electrode 17, then oscillating plate 12 returns original position, and the internal pressure of ejection chamber 13 uprises, and sprays the drop of printing ink etc. from nozzle 8.Like this, in this 1st embodiment, constitute electrostatic actuator by oscillating plate 12 and opposite electrode 17.In addition, comprise oscillating plate 12 and opposite electrode 17, even drive circuit 25, electrostatic actuator all be called.

In this 1st embodiment, as the example of using electrostatic actuator of the present invention, though the droplet discharging head of expression static type of drive, but the droplet discharging head shown in this 1st embodiment with and manufacture method, also can be applicable in MEMS (the Micro Electro Mechanical System) equipment etc. of micropump etc.

Fig. 2 is that the part of slot part 19, opposite electrode 17 and the oscillating plate 12 of Fig. 1 is amplified sectional side elevation.Fig. 2 (a) is to comprise opposite electrode 17 at interior amplification sectional side elevation, and Fig. 2 (b) is an amplification sectional side elevation of removing the state behind the opposite electrode 17.And among Fig. 2 (a) and Fig. 2 (b), the long side direction of expression slot part 19, the short side direction of slot part 19 is to the direction at the back side of paper from the front of paper.

Shown in Fig. 2 (b), stair-stepping slot part 19, the central portion of long side direction the darkest (degree of depth A3), the both ends side of central portion is than central portion shallow (degree of depth A2), the part the most shallow (degree of depth A1) at two ends.That is, set up the relation of A3＞A2＞A1.In addition, though Fig. 1 and slot part 19 shown in Figure 2 become 3 sections stepped, also can be more than 4 sections.And preferably the section of the slot part 19 shown in Fig. 2 (b) is poor, along with the both ends from slot part 19 diminish successively to central portion.But, be not that certain needs are followed like that.It also can be the relation of (A2-A1) 〉=(A3-A2).In the droplet discharging head 1 in the present embodiment 1, satisfy the relation of A1＞(A2-A1)＞(A3-A2).

In the droplet discharging head 1 shown in Fig. 2 (a), form opposite electrode 17 in the inside of stair-stepping slot part 19.This opposite electrode 17, by splash ITO and forming for example, general opposite electrode 17 is by forming at the identical thickness in the inside of slot part 19.Like this, when the par of opposite electrode 17 at slot part 19, when forming by identical thickness, the thickness that makes opposite electrode 17 is t, the gap length between oscillating plate 12 and the opposite electrode 17 (length in gap 20) then, central portion at the long side direction of slot part 19 is G3=A3-t, is G2=A2-t in the both ends of central portion side, and the part at two ends is G1=A1-t.

According to above-mentioned relation, set up the relation of G3＞G2＞G1, and set up the relation of G1＞(G2-G1)＞(G3-G2).That is, the gap length between oscillating plate 12 and the opposite electrode 17 is, along with the central portion from the long side direction of slot part 19 shortens to both ends, and the difference of the gap length of each section difference, along with the both ends from slot part 19 diminish to central portion.

In addition, in this 1st embodiment, the thickness t of opposite electrode 17 par in slot part 19, it forms also thicker than any section difference that forms stair-stepping slot part 19.It sets up the relation of t＞(A2-A1)＞(A3-A2).Like this, prevent the imbalance (disconnection) of opposite electrode 17 in the segment difference section.

Fig. 3 and Fig. 4 are the figure that is used for describing at driving voltage and gap length, and this driving voltage is used for driving makes oscillating plate dock with opposite electrode.In addition, among Fig. 3 and Fig. 4, illustrate though be out of shape such module successively from the both ends side of the strongest slot part 19 of electrostatic force by oscillating plate 12, actual oscillating plate 12, generally both ends and the central portion at slot part 19 almost begins to drive simultaneously.In addition, among Fig. 3 and Fig. 4, so-called oscillating plate 12 is included in the dielectric film 16 that gap 20 sides of oscillating plate 12 form, and has omitted diagram.Further, among Fig. 3 and Fig. 4, for easy understanding, diagram makes the thickness of opposite electrode 17 thinner than actual thickness.

Fig. 3 (a) is the sectional side elevation of end (left side) of expression slot part 19.Droplet discharging head shown in Fig. 3 (a) in addition, identical with Fig. 1 and droplet discharging head 1 shown in Figure 2, represent the initial position of oscillating plate 12 by chain-dotted line.And, be made as Δ G1=(G2-G1).

Make that G1 is the gap length of slot part 19 at both ends, make that x is the displacement of oscillating plate 12 to opposite electrode 17 directions, make that V is a potential difference between oscillating plate 12 and the opposite electrode 17, then the electrostatic force Fin that acts between oscillating plate 12 and the opposite electrode 17 at the both ends of slot part 19 is represented by following formula.

And, when oscillating plate 12 bendings, act on the recuperability Fp in the oscillating plate 12, be expressed from the next.

Constant C in the formula (2) in addition is by regulations such as the material parameter of oscillating plate 12, sizes.

At this shown in Fig. 3 (b), about the oscillating plate 12 and the gap length at the both ends of slot part 19 is that the part of G1 is docked, as long as during the displacement of oscillating plate 12 changes, give all the time to apply between oscillating plate 12 and the opposite electrode 17 to make electrostatic force Fin surpass the such potential difference V of recuperability Fp _HitGet final product.

If represent, then set up all the time with formula

F _in(x，V _hit)≥F _p(x) ……(3)

Fig. 3 (c), for the both ends that are illustrated in slot part 19 act on electrostatic force Fin between oscillating plate 12 and the opposite electrode 17, with the curve map that acts on the relation of the recuperability Fp in the oscillating plate 12.Fig. 3 (c) in addition is for adopting the data of general droplet discharging head, G1=200 (nm).In addition, adopt the unit of voltage (V), adopt the displacement of millimicron (nm) as oscillating plate 12 as potential difference.

Shown in Fig. 3 (c), when the potential difference between oscillating plate 12 and the opposite electrode 17 is 14V (curve B of Fig. 3 (c)) and 16V (curve C of Fig. 3 (c)), some partial electrostatic power F _InDo not surpass recuperability F _p(the straight line A of Fig. 3 (c)), oscillating plate 12 are not that the part of G1 is docked with the potential difference at the both ends of slot part 19.But, when the potential difference between oscillating plate 12 and the opposite electrode 17 is 20V (curve D of Fig. 3 (c)), because electrostatic force F _InAll the time surpass recuperability F _p, so oscillating plate 12 and the gap length at the both ends of slot part 19 are that the part of G1 is docked.That is, become V _Hit=20 (V).According to formation of the present invention, by with this potential difference V _Hit Drive oscillating plate 12, thereby all of oscillating plate 12 docked with opposite electrode 17, it describes below reason.

Shown in Fig. 3 (b), under oscillating plate 12 and state that the part of the gap length G1 of opposite electrode 17 is docked, be the electrostatic force F of partial action between oscillating plate 12 and opposite electrode 17 of G2 in the gap length of slot part 20 _In1And act on recuperability Fp1 (with reference to Fig. 3 (b)) in the oscillating plate 12, be expressed from the next.

$F_{\mathrm{in}1}=F_{\mathrm{in}}(\mathrm{\&Delta;<figure-callout\; id="1"\; label="G"\; filenames="C20061000425000241.png,C20061000425000251.png"\; state="\{\{state\}\}">G</figure-callout>}1,V_{\mathrm{hit}})=\mathrm{\&alpha;}\left(\frac{V_{\mathrm{hit}}}{\mathrm{\&Delta;G}1}\right)\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

${\mathrm{<figure-callout\; id="1"\; label="F\; p"\; filenames="C20061000425000241.png,C20061000425000251.png"\; state="\{\{state\}\}">F</figure-callout>}}_p=F_p\left(G1\right)=\frac{G1}{C}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(5\right)$

At this, if making, setting Δ G1 satisfies Fp1＜Fin1, then the potential difference between oscillating plate 12 and the opposite electrode 17 can not compare V _HitGreatly, can make gap length is oscillating plate 12 bendings of the part of G2, produces bending distortion such shown in Fig. 4 (d).

At this moment, in gap length be the partial action of G2 between oscillating plate 12 and opposite electrode 17 electrostatic force Fin and act on recuperability Fp in the oscillating plate 12, be expressed from the next.In addition, formula (6), (7) are, oscillating plate 12 further produces distortion from the state of Fig. 3 (b), will be that the displacement that the part of G2 produces bending is made as y (nm) (with reference to Fig. 4 (d)) in gap length.

$F_{\mathrm{in}}=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{\mathrm{\&Delta;G}1-y}\right)}^2=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{G1-(G1-\mathrm{\&Delta;<figure-callout\; id="1"\; label="G"\; filenames="C20061000425000241.png,C20061000425000251.png"\; state="\{\{state\}\}">G</figure-callout>}1+y)}\right)}^2=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{G1-(x-\mathrm{\&Delta;G}1)}\right)}^2$

$=\mathrm{Fin}(x-\mathrm{\&Delta;<figure-callout\; id="1"\; label="G"\; filenames="C20061000425000241.png,C20061000425000251.png"\; state="\{\{state\}\}">G</figure-callout>}1,V_{\mathrm{hit}})\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(6\right)$

F _p＝F _p(G1+y)＝F _p(x) ……(7)

And in formula (6), (7), utilize the relation of x=G1+y that formula is put in order.

Fig. 4 (e) is for the electrostatic force Fin of partial action between oscillating plate 12 and opposite electrode 17 of the gap length G2 that is illustrated in slot part 19, with the curve map of the relation that acts on the recuperability Fp in the oscillating plate 12.And, in Fig. 4 (e), Δ G1=67 (nm), G2=G1+ Δ G1=200+67=267 (nm).In addition, in Fig. 4 (e), straight line A, straight line D, with identical shown in Fig. 3 (c), curve E is the part of the gap length G2 of relevant slot part 19.

As Fig. 4 (e) if shown in suitably set Δ G1, electrostatic force F all the time then _InSurpass recuperability Fp, the potential difference between oscillating plate 12 and the opposite electrode 17 still is V _Hit, oscillating plate 12 is docked with the part of the gap length G2 of slot part 19.

Similarly, be that the part of G3 is considered about the gap length of the central portion of slot part 19.

Under oscillating plate 12 and state that the part of the gap length G2 of opposite electrode 17 is docked, the part at the gap length G3 of slot part 20 acts on the electrostatic force F between oscillating plate 12 and the opposite electrode 17 _In2And act on recuperability F in the oscillating plate 12 _P2, be expressed from the next.And, be made as Δ G2=(G3-G2) at this.

$F_{\mathrm{in}2}=F_{\mathrm{in}}(\mathrm{\&Delta;<figure-callout\; id="2"\; label="G"\; filenames="C20061000425000241.png,C20061000425000242.png"\; state="\{\{state\}\}">G</figure-callout>}2,V_{\mathrm{hit}})=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{\mathrm{\&Delta;G}2}\right)}^2\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(8\right)$

${\mathrm{<figure-callout\; id="2"\; label="F\; p"\; filenames="C20061000425000241.png,C20061000425000242.png"\; state="\{\{state\}\}">F</figure-callout>}}_p=F_p\left(G2\right)=\frac{G2}{C}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(9\right)$

At this,, setting Δ G2 satisfies F if making _P2＜F _In2, then the potential difference between oscillating plate 12 and the opposite electrode 17 can be greater than V _Hit, can make gap length is oscillating plate 12 bendings of the part of G3, produces bending distortion such shown in Fig. 4 (f).

At this moment, be the part of G3 in gap length, act on the electrostatic force F between oscillating plate 12 and the opposite electrode 17 _InAnd act on recuperability F in the oscillating plate 12 _pBe expressed from the next.In addition in formula (10), (11), with oscillating plate 12 in the part bending of gap length G3 displacement be made as z (nm) (with reference to Fig. 4 (f)).

$F_{\mathrm{in}}=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{\mathrm{\&Delta;G}2-z}\right)}^2=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{G1-(G1-\mathrm{\&Delta;<figure-callout\; id="2"\; label="G"\; filenames="C20061000425000241.png,C20061000425000242.png"\; state="\{\{state\}\}">G</figure-callout>}2+z)}\right)}^2=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{G1-(x-\mathrm{\&Delta;G}1-\mathrm{\&Delta;G}2)}\right)}^2$

$F_{\mathrm{in}}(x-\mathrm{\&Delta;G}1-\mathrm{\&Delta;<figure-callout\; id="2"\; label="G"\; filenames="C20061000425000241.png,C20061000425000242.png"\; state="\{\{state\}\}">G</figure-callout>}2,V_{\mathrm{hit}})\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(10\right)$

F _p＝F _p(G2+z)＝F _p(x) ……(11)

And in formula (10), (11), utilize the relation of x=G2+z=G1+ Δ G1+z that formula is put in order.

Fig. 4 (g) for the gap length that is illustrated in slot part 19 is the part of G3, acts on the electrostatic force Fin between oscillating plate 12 and the opposite electrode 17, with the curve map of the relation that acts on the recuperability Fp in the oscillating plate 12.And, in Fig. 4 (g), Δ G2=54 (nm), G3=G1+ Δ G1+ Δ G2=200+67+54=321 (nm).In addition among Fig. 4 (g), straight line A, straight line D, straight line E, with identical shown in Fig. 4 (e), curve F is the part of the gap length G3 of relevant slot part 19.

Shown in Fig. 4 (g), if suitably set Δ G2, electrostatic force F all the time then _InSurpass recuperability Fp, the potential difference between oscillating plate 12 and the opposite electrode 17 still is V _Hit, oscillating plate 12 is docked with the part of the gap length G3 of slot part 19.

At this,, be used to make Δ G1 that oscillating plate 12 docks with opposite electrode 17 and the condition of Δ G2 to consider about being the part of G2 and G3 in gap length.

Satisfy F in order to obtain _p(0)＜F _In(0, V _Hit), F _P1＜F _In1, F _P2＜F _InSeparate, at this, for convenience's sake, make F _P1=F _In1, F _P2=F _In2About recuperability, because F _p(0)＜F _P1＜F _P2, therefore set up F _In(0, V _Hit)＜F _In1＜F _In2

If the substitution following formula then obtains the relational expression about G1, Δ G1, Δ G2 in the formula.

$F_{\mathrm{in}}(0,V_{\mathrm{hit}})=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{G1}\right)}^2\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(12\right)$

$F_{\mathrm{in}1}=F_{\mathrm{in}}(\mathrm{\&Delta;<figure-callout\; id="1"\; label="G"\; filenames="C20061000425000241.png,C20061000425000251.png"\; state="\{\{state\}\}">G</figure-callout>}1,V_{\mathrm{hit}})=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{\mathrm{\&Delta;G}1}\right)}^2\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(13\right)$

$F_{\mathrm{in}2}=F_{\mathrm{in}}(\mathrm{\&Delta;<figure-callout\; id="2"\; label="G"\; filenames="C20061000425000241.png,C20061000425000242.png"\; state="\{\{state\}\}">G</figure-callout>}2,V_{\mathrm{hit}})=\mathrm{\&alpha;}{\left(\frac{V_{\mathrm{hit}}}{\mathrm{\&Delta;G}2}\right)}^2\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(14\right)$

That is, obtain the relational expression of G1＞Δ G1＞Δ G2.If like this as the section official post of above-mentioned setting slot part 19 get G1＞(G2-G1)＞(G3-G2), then with at the both ends of slot part 19 (part that the gap is the shortest), be used for the driving voltage Vhit that oscillating plate 12 docks with opposite electrode 17, the integral body of oscillating plate 12 is docked with opposite electrode 17.Like this, driving voltage can be reduced, the jetting amount of the drop in the droplet discharging head 1 for example can be guaranteed simultaneously.In addition, about the detailed description of the section difference that is used to make driving voltage that above-mentioned oscillating plate 12 docks with opposite electrode 17 and slot part 19, even the section difference of slot part 19 be under the situation more than 4 sections too.

Fig. 5, Fig. 6 and Fig. 7 are the sectional side elevation of the manufacturing process of the droplet discharging head of representing the 1st embodiment of the present invention.Fig. 5 to Fig. 7, the operation of expression shop drawings 1 and droplet discharging head 1 shown in Figure 2, and only represent the periphery of slot part 19.The manufacture method of droplet discharging head 1 is not to be defined in Fig. 5 to shown in Figure 7 in addition.

At first, the substrate 3a (Fig. 5 (a)) for preparing thickness for example and be 2～3mm and form by pyrex, will be for example after the thickness of substrate 3a is ground to till the 1mm by mechanical lapping, with for example fluoric acid aqueous solution integral body of substrate 3a is carried out 10～20 μ m etchings, remove affected layer (Fig. 5 (b).The removal of this affected layer can be the dry ecthing of carrying out with SF6 for example etc., also can be the spin etch that carries out with the fluoric acid aqueous solution.When carrying out dry ecthing, can affected layer effectively be removed at the single face of substrate 3a, do not need the protection of opposing face.In addition, when being rotated etching, needed etching solution is a small amount of, and owing to supply with new etching solution all the time, therefore can carry out stable etching.And, in the operation of Fig. 5 (b), replace mechanical lapping, can only make substrate 3a attenuation by for example fluoric acid aqueous solution.And after the operation of Fig. 5 (b), by carrying out the surface treatment of substrate 3a, the wetability of substrate 3a is improved, thereby can promote the etching of back operation with acidic aqueous solution.

Then, by for example single face integral body of the substrate 3a of splash after attenuation, form the etching mask of forming by chromium (Cr) 30 (Fig. 5 (c)).

Then form the pattern of the resist (not shown) of given shape on the surface of etching mask 30, carry out etching, form etching mask 30 and be peristome (Fig. 5 (d)) with central portion (part of the gap length G3) corresponding shape of slot part 19 by photoetching process.In addition, this peristome generally forms a plurality of oblong-shapeds.

Then, by substrate 3a being carried out etching, thereby form the 1st slot part 19b (Fig. 5 (e)) with for example fluoric acid aqueous solution.In addition, etch quantity at this moment (etched depth) becomes the A3-A2 among Fig. 2 (b).

Afterwards, form the pattern of the resist (not shown) of given shape once more on the surface of etching mask 30 by photoetching process, carry out etching, become mode with part (with reference to Fig. 1, Fig. 2) corresponding shape of the gap length G2 of slot part 19 according to etching mask 30, launch peristome (Fig. 6 (f)) in long side direction (the paper left and right directions of Fig. 5 and Fig. 6) both sides.

Then, by substrate 3a being carried out etching, thereby form the 2nd slot part 19c (Fig. 6 (g)) with for example fluoric acid aqueous solution.And make etch quantity (etched depth) at this moment, become (A2-A1) among Fig. 2 (b).In addition, the 2nd slot part 19c shown in Fig. 6 (g), becomes 2 sections shape.

Then, form the pattern of the resist (not shown) of given shape once more on the surface of etching mask 30 by photoetching process, carry out etching, become mode with part (with reference to Fig. 1, Fig. 2) corresponding shape of the gap length G1 of slot part 19 according to etching mask 30, launch peristome (Fig. 6 (h)) in the long side direction both sides.In this 1st embodiment, in the operation of Fig. 6 (h), the etching mask 30 that also will become the part of connectivity slot 19a is also removed in addition.

And,, etching mask 30 is removed (Fig. 6 (i)) with for example fluoric acid aqueous solution by after for example substrate 3a being carried out etching formation slot part 19 and connectivity slot 19a with the fluoric acid aqueous solution.At this moment etch quantity (etched depth) becomes the A1 among Fig. 2 (b).Like this, form the slot part 19 of the stairstepping of 3 sections tabular surfaces with degree of depth A1, A2, A3.

In addition, by above-mentioned operation repeatedly, thereby can form tabular surface slot part 19 more than 4 sections.

Further, by splash ITO (Indium Tin Oxide) film 31 for example, thereby form ITO film (Fig. 6 (j)) at the face of one side such as formation slot part 19 grades of substrate 3a.In addition, the thickness of ITO film 31 at this moment, it forms than any one section difference thicker (thickness t of above-mentioned opposite electrode) that forms stair-stepping slot part 19.And the pattern (not shown) by photoetching process formation resist carries out etching to ITO film 31, divides and forms opposite electrode 17, forms electrode base board 3 (Fig. 6 (k)).Like this, the gap length that forms between oscillating plate 12 and the opposite electrode 17 is the opposite electrode that end side G1, G2, G3 formed 17 apart from slot part 19.

Thereafter, with for example thickness is that 525 μ m and the electrode base board 3 that forms the silicon substrate 2a of the dielectric film of being made up of silica etc. 16 and form opposite electrode 17 etc. in the operation of Fig. 6 (k) at single face are heated to be for example 360 ℃, silicon substrate 2a is connected with anode, electrode base board 3 is connected with negative electrode, and the voltage that applies about 800V carries out anodic bonding (Fig. 7 (l)).In addition, silicon substrate 2a and electrode base board 3 engage forming the face of dielectric film 16 and the face of formation opposite electrode 17 grades.In addition, dielectric film 16 can form by for example thermal oxide or plasma CVD.

After silicon substrate 2a and electrode base board 3 are carried out anodic bonding,, the integral thinned of silicon substrate 2a is for example become till the thickness 140 μ m (Fig. 7 (m)) by for example mechanical lapping.After this carrying out mechanical lapping,, preferably carry out dry ecthing by potassium hydroxide aqueous solution etc. in order to remove affected layer.And replacement mechanical lapping also can make silicon substrate 2a attenuation by the wet etching with potassium hydroxide aqueous solution.

Then, on silicon substrate 2a (opposing face of the face of bonding electrodes substrate 3) whole, form for example silicon oxide film of thickness 1.5 μ m by the TEOS plasma CVD.

On this silicon oxide film, be formed for forming the recess that becomes ejection chamber 13, pattern part, resist that becomes the recess of storeroom 14 and become the recess of spout then, the silicon oxide film etching of this part is removed.

Then, by silicon substrate 2a being carried out the anisotropy wet etching with potassium hydroxide aqueous solution etc., thereby become the recess 13a of ejection chamber 13, the recess (not shown) that becomes the recess (not shown) of storeroom 14 and become spout 15 afterwards, silicon oxide film is removed (Fig. 7 (n)).And in the wet etching operation of Fig. 7 (n), original adoption is the potassium hydroxide aqueous solution of weight 35% for example, just can adopt the potassium hydroxide aqueous solution of weight 3% thereafter.The surface roughness that like this, just can suppress oscillating plate 12.

In addition; after the operation of Fig. 7 (n); become in formation on the face of recess 13a etc. of ejection chamber 13 of silicon substrate 2a, form the diaphragm of forming by silica etc. of anti-drop the (not shown) of thickness 0.1 μ m for example by for example CVD, but in Fig. 7 (n), the diaphragm of anti-the drop is omitted.

Then,, formation is become the nozzle plate 4 of the recess of nozzle 8 and spout 15, engage (Fig. 7 (o)) with silicon substrate 2a (hole substrate 2) by adhesive by ICP (Inductively Coupled Plasma) discharge etc.

At last, by engaging the bonded substrate cutting (cut-outs) behind for example hole substrate 2, electrode base board 3 and the nozzle plate 4 thus droplet discharging head 1 is finished in separation.

In this 1st embodiment, owing to form stair-stepping opposite electrode 17, this is stepped to be gap length between oscillating plate 12 and the opposite electrode 17, along with the central portion from the long side direction of slot part 19 shortens to the end, therefore compare in the stepped situation of minor face (width) direction with slot part 19, can provide bigger moment for oscillating plate 12, driving voltage is effectively reduced.In addition because at the central portion of slot part 19, gap length is the longest, and in the end of slot part 19, gap length is the shortest, so oscillating plate 12 begins distortion from both ends, can driving voltage effectively be reduced.

And, because it is poor to form the section of stair-stepping slot part 19, according to along with from the end of slot part 19 to central portion and the mode of diminishing forms, so opposite electrode 17 also forms consistent with this shape.Like this, in the shortest part of the tip-clearance of slot part 19 length,, oscillating plate 12 integral body are docked with opposite electrode 17 with the driving voltage that oscillating plate 12 docks with opposite electrode 17.Like this, driving voltage is reduced, guarantee the spray volume of the drop in the droplet discharging head 1 simultaneously.

And, different with said method, will form the hole substrate 2 of the runner of oscillating plate 12, ejection chamber 13 etc., the method that engages with the electrode base board 3 that forms opposite electrode 17 in addition in advance.

In addition, electrostatic actuator be not applied under the situation of droplet discharging head, need on the substrate parts that forms oscillating plate 12, forming runner etc., also do not needing the assembling of nozzle plate 4.

(the 2nd embodiment)

Fig. 8 is the signal pie graph of the electrostatic actuator of the present invention's the 2nd embodiment.This electrostatic actuator possesses: the oscillating plate 12A that forms by the silicon of the electrode that constitutes a side etc., with formed on electrode base board 3A and with oscillating plate 12A across the opposed opposite electrode 17A of gap 20A.Oscillating plate 12A is also referred to as vibrating membrane in some cases.And, though with opposed of the opposite electrode 17A of oscillating plate 12A, cover dielectric film, this and not shown.And then, between oscillating plate 12A and opposite electrode 17A, be connected with the drive circuit 25A that is used for to supply drive pulse between these electrodes.

Opposite electrode 17A, the plane on being formed at electrode base board 3A is for roughly forming in the OBL slot part 19A, and according to along with the central portion to the long side direction of slot part 19A, gap 20A launches the mode of (becoming big), forms multistage opposite electrode 17A.In addition, Fig. 8, the long side direction of expression slot part 19A, the short side direction of slot part 19A is the direction from front, paper front to the back side.

When the electrostatic actuator of Fig. 8, opposite electrode 17A is 4 sections formations with 4 section differences, about almost the symmetry form.The gap 20A of each section of opposite electrode 17A and oscillating plate 12A becomes G1, G2, G3 from the long side direction end along the slot part 19A of opposite electrode 17A respectively to central portion.This gap 20A, its central portion is the wideest, along with from central portion to the long side direction both end sides and narrow down (diminishing).That is,

Become G4＞G3＞G2＞G1.

When the electrostatic actuator that night, droplet ejection head was used, gap 20A can become for example G1=80nm, G2=95m, G3=110nm, G4=120nm.

And the section of each section of preferred opposite electrode 17A is poor, forms according to the mode that diminishes to central portion along with the long side direction end from slot part 19A.But, be not must be according to like this.So long as (G2-G1) 〉=(G3-G2) 〉=(G4-G3), but G1 〉=(G2-G1) get final product.If according to like this,,, oscillating plate 12A integral body is docked with opposite electrode 17A just easily with oscillating plate 12A and the driving voltage that opposite electrode 17A docks then in the narrowest part of gap 20A.

The thickness of opposite electrode 17A, generally each section at long side direction is constant thickness.Therefore, if the degree of depth of the slot part 19 of the order part corresponding with width G 1, G2, G3, the G4 of gap 20A is A1, A2, A3, A4, the thickness that makes opposite electrode 17A is t, A1=G1+t then, A2=G2+t, A3=G3+t, A4=G4+t.That is A4＞A3＞A2＞A1.

In addition, make the section of slot part 19A poor, corresponding with the section difference of opposite electrode 17A and form, preferably utilize the section poor of slot part 19A, make also form among the opposite electrode 17A identical section poor.

And, the thickness t of preferred opposite electrode 17A, it forms thicker than the arbitrary section difference of each section that forms stair-stepping slot part 19A.Like this, be because because

The relation of t＞(A2-A1)＞(A3-A2)＞(A4-A3) is set up, and therefore can prevent the reason of the imbalance (disconnection) in the segment difference section of opposite electrode 17A.

In addition, opposite electrode 17A and slot part 19A are not limited to 4 sections formation, even also can as 2 sections, 3 sections formation or the formation more than 5 sections according to the size of electrostatic actuator.

By glass substrate is carried out etching etc., form slot part 19A, and then in this slot part 19A, carry out for example ITO of splash, make it corresponding with the shape of groove etc. and film forming, make the ITO after the film forming form pattern, form opposite electrode, thereby obtain opposite electrode 17A.The electrode base board 3A and the oscillating plate 12A that form this opposite electrode 17A are engaged (for example anodic bonding), can access electrostatic actuator.In addition, carry out anodic bonding, afterwards, silicon substrate is processed, be formed on the oscillating plate 12A, also can access electrostatic actuator even will form electrode base board 3A and the silicon substrate of opposite electrode 17A.

In above-mentioned electrostatic actuator, between oscillating plate 12A and opposite electrode 17A, if applying the oscillating plate 12A that makes the part corresponding with the G1 of gap 20A docks needed enough voltage with opposite electrode 17A, then keep the 1st section the narrowest opposite electrode 17A of oscillating plate 12A and gap 20A to dock.At this moment, with G1 and the corresponding boundary portion of G2 of gap 20A, gap 20A temporarily becomes (G2-G1), thus very big electrostatic attraction pressure is acted among the oscillating plate 12A, the oscillating plate 12A of the part corresponding with the G2 of gap 20A also docks with opposite electrode 17A because of identical voltage.Progressively effect like this, bring out continuously till the part suitable with the wideest G4 of gap 20A, its result is, so that the oscillating plate 12A of the part corresponding with the G1 of gap 20A docks needed voltage with opposite electrode 17A, the integral body of oscillating plate 12A is docked with opposite electrode 17A.Below, will be called lasting butt joint as the method that above-mentioned oscillating plate 12A docks with opposite electrode 17A.

As above-mentioned, though the electrostatic actuator of the 2nd embodiment is also basic same with the 1st embodiment, but in the 2nd embodiment, also created a kind of scheme, in its each section boundary portion (perhaps section difference transfer portion) 24 at opposite electrode 17A, by opposite electrode 17A oscillating plate 12A is held more firmly, and is used for bringing out more reliably lasting butt joint.Below, the formation of this boundary portion (perhaps section difference transfer portion) 24 is specifically described.

Fig. 9 is the 1st upward view that constitutes of the segment difference section of the opposite electrode 17A of key diagram 8.Among Fig. 9, as shown, the segment difference section of each section of the opposite electrode 17A of electrostatic actuator (each section face), it constitutes, boundary portion at adjacent epimere (more shallow section face) and hypomere (darker section face), the part of the end of hypomere side (is central portion at this) is outstanding for rectangular-shaped, enters to upper end side.Like this, attract the electrostatic attraction of oscillating plate 12A in this segment difference section, with in the butt joint of epimere portion, in the butt joint of boundary portion, produce in the order of the butt joint of hypomere portion, by the butt joint of leading portion part, making next, the electric field of the part of butt joint uprises successively.Like this, by constant voltage, just from the long side direction end of opposite electrode 17A to central portion, carry out docking of oscillating plate 12A and opposite electrode 17A.

In addition, opposite with the situation of Fig. 9, also can be the mode that enters in lower end side according to the part of the end of the epimere side of opposite electrode 17A and constituting.

Figure 10 is the 2nd upward view that constitutes of the segment difference section of the opposite electrode 17A of key diagram 8.The formation of Figure 10 is the variation of formation shown in Figure 9, comprises the boundary portion of the segment difference section of opposite electrode 17A, protrudes taper according to the central portion of the end of hypomere side, and the mode that enters to the epimere side constitutes.According to like this, make the attraction equalization more of the boundary portion of section difference, to carry out the continuous butt joint of oscillating plate 12A more reliably to opposite electrode 17A with opposite electrode 17A.And, even at this, the also formation of the mode that can enter to the hypomere side according to the central portion of the end of the epimere side of opposite electrode 17A.

In addition, in Figure 10, with the opposite electrode width and the slot part width of the long side direction quadrature of slot part 19A, it is wideer than upper end side that it constitutes the hypomere side that makes them.Like this, in the very wide part of gap 20A,, therefore be more prone to bring out lasting butt joint because the electrostatic attraction of oscillating plate 12A correspondence acts in the very wide scope.And, also avoid the unfavorable phenomenon of the variation of the groove width that causes because of the pattern when slot part 19A forms dislocation easily.

Figure 11 is the 3rd upward view that constitutes of segment difference section of the opposite electrode 17A of key diagram 8.In Figure 11, comprise the boundary portion of the segment difference section of opposite electrode 17A, constitute as being used for bringing out the section difference transfer portion 24 of above-mentioned lasting butt joint reliably.That is, the end of the hypomere on adjacent in the hypomere, the protuberance of formation island.Though the height of this protuberance is not to be defined,, preferably become the height identical with adjacent epimere according to the viewpoint of opposite electrode manufacture view.And, though in some cases, according to the number of its this protuberance of shape be 1 just can, preferably be provided with a plurality of, especially preferably with the very near intensive configuration protuberance of part of epimere, then along with distance becomes far and sparsely configuration.

Like this by comprising the boundary portion section of the setting difference transfer portion 24 of segment difference section, thereby should shift the electrostatic attraction of part, becoming will be at the attraction and the pressure after the attraction of hypomere portion is average of the epimere portion of adjacent segment, more properly bring out with darker gap continue dock.Therefore, can make this driving voltage step-down.

In addition, replace the end of the hypomere of hypomere on opposite electrode 17A adjacent that protuberance is set, even, also can access same effect as the formation that forms the recess of island in the end of adjacent epimere.

The electrostatic actuator of the 2nd embodiment also can be with the method manufacturing of the 1st embodiment.Under this situation, about the boundary portion of each section difference of the opposite electrode 17 that forms Fig. 9～shown in Figure 11 or each shape of section difference transfer portion 24, make the slot part 19 of electrode base board 3 corresponding in advance with their shape, preferred these shapes form because of the shape of this slot part 19, but, also can utilize mask to be used to form the splash etc. of opposite electrode 17 by repeated multiple times, thereby form.

In addition, utilize the electrostatic actuator of the 2nd embodiment, also can obtain the droplet discharging head same with the illustrated droplet discharging head of the 1st embodiment 1.

(the 3rd embodiment)

Figure 12 is for representing droplet discharging head of the present invention, for example possessing the stereogram of drop liquid discharging device one example of the 3rd embodiment of the present invention of droplet discharging head 1.Drop liquid discharging device 100 as shown in figure 12 is that ejection liquid is the ink-jet printer of printing ink.As illustrating, because the driving voltage of droplet discharging head 1 is very low, the spray volume of drop is also enough, therefore utilizes the drop liquid discharging device 100 of this device, and low consumption electric power and discharge performance are also good.

And droplet discharging head 1 and drop liquid discharging device 100 except that printing ink, also can be applicable to comprise the ejection of various drops such as the solution of the filtering material of colour filter, the solution that comprises the luminescent material of organic EL display, biofluid.

In addition, electrostatic actuator of the present invention is not limited to be applied to above-mentioned droplet discharging head, also can be applicable in other various device.If enumerate example, pump portion, the switch drive portion of photoswitch, a plurality of microminiature speculums of configuration that micropump is then arranged, with these mirror tilts, the mirror drive portion of the mirror equipment of control direction of light, also have in the drive division etc. of laser operations speculum of laser printer and can use electrostatic actuator.By the electrostatic actuator shown in lift-launch the 1st embodiment in these equipment, thereby just can obtain very little driving voltage and the good equipment of action property.

Claims (17)

1, a kind of electrostatic actuator possesses the oscillating plate of the electrode that constitutes a side and is formed with and the electrode base board of this oscillating plate across the opposed opposite electrode in gap, it is characterized in that,

Described opposite electrode, formed flat shape is that roughly OBL slot part forms on described electrode base board, and forms along with the central portion to the long side direction of described slot part, described gap becomes big a plurality of sections.

2, electrostatic actuator according to claim 1 is characterized in that,

The section difference of each of described opposite electrode section is along with the long side direction end from described slot part is close to central portion, to diminish gradually.

3, electrostatic actuator according to claim 1 and 2 is characterized in that,

In each section boundary portion of described opposite electrode, adjacent segment forms according to the mode that enters into the other side's side mutually.

4, electrostatic actuator according to claim 1 and 2 is characterized in that,

In each section boundary portion of described opposite electrode,, form at least the section difference transfer portion that forms by 1 recess or, form section poor transfer portion that forms by at least 1 protuberance in the hypomere end of described adjacent section in the epimere end of adjacent section.

5, electrostatic actuator according to claim 1 and 2 is characterized in that,

With the width of the long side direction quadrature of described opposite electrode be, along with from the long side direction end of described slot part to central portion, each each section face broadens successively.

6, electrostatic actuator according to claim 1 and 2 is characterized in that,

Described electrode base board is made of pyrex.

7, electrostatic actuator according to claim 1 and 2 is characterized in that,

Described opposite electrode is made of ITO.

8, a kind of droplet discharging head is characterized in that,

Possess each described electrostatic actuator in the claim 1～7, described oscillating plate constitutes and drop is kept and with the wall of the balancing gate pit of its ejection.

9, a kind of drop liquid discharging device is characterized in that, possesses the described droplet discharging head of claim 8.

10, a kind of equipment, it possesses each described electrostatic actuator in the claim 1～7.

11, a kind of manufacture method of electrostatic actuator comprises:

Groove forms operation, implements repeatedly etching on electrode base board, and form flat shape and be oblong-shaped roughly, and along with the stair-stepping slot part that deepens to the central portion of its long side direction;

Electrode forming process with the electrode material film forming, forms the opposite electrode that has with the corresponding section poor shape of section difference of this slot part in the inside of described slot part; With

Engage operation, with the electrode base board after described each operation that is through with, with the oscillating plate that constitutes side's electrode or form the substrate of oscillating plate afterwards, according to described opposite electrode is engaged with the opposed mode of oscillating plate formation predetermined face of described oscillating plate or described substrate.

12, the manufacture method of electrostatic actuator according to claim 11 is characterized in that,

Make the section of each section of described slot part poor, along with from the long side direction end of described slot part to central portion, diminish gradually.

13, according to the manufacture method of claim 11 or 12 described electrostatic actuators, it is characterized in that,

With the width of the long side direction quadrature of described slot part, along with from the long side direction end of described slot part to central portion, each each section face broadens successively.

14, according to the manufacture method of claim 11 or 12 described electrostatic actuators, it is characterized in that,

Make the thickness of the par of the opposite electrode that forms in the inside of described slot part, thicker than any section difference of described slot part.

15, according to the manufacture method of claim 11 or 12 described electrostatic actuators, it is characterized in that,

Form in the operation at described groove, in each section boundary portion of described slot part, the mode that enters into the other side's side according to adjacent section mutually forms groove.

16, according to the manufacture method of claim 11 or 12 described electrostatic actuators, it is characterized in that,

Form in the operation at described groove,, form at least the section difference transfer portion that forms by 1 recess in the epimere end of adjacent section or forms section poor transfer portion that forms by 1 protuberance at least in described adjacent hypomere end in each section boundary portion of described slot part.

17, a kind of manufacture method of droplet discharging head is characterized in that,

Use the manufacture method of each described electrostatic actuator in the described claim 12～16, constitute and drop to be kept and the pressure oscillation mechanism of the balancing gate pit of its ejection.

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