CN101915989B - Electric field force-controlled liquid lens - Google Patents

Abstract

The invention discloses an electric field force-controlled liquid lens. In the liquid lens, a barrier wall (3) is manufactured on a second transparent substrate (4), a second electrode (8) is covered on the barrier wall (3), a first liquid (5) is injected into the second electrode (8), a second liquid (2) is covered on the first liquid (5), a first electrode (7) is covered on a first transparent substrate (1), and the first electrode (7) is covered on the second liquid (2). The liquid lens structure does not need insulation layers, can not cause electrochemical reactions and has the advantages of fixed lens axis, low drive voltage and simple structure.

Description

A kind of liquid lens of electric field force control

Technical field

The present invention relates to a kind of liquid lens structure, thereby especially relate to a kind of dielectrophoretic liquid lens arrangement that liquid form changes focal length that under Control of Voltage, can effectively change.

Background technology

Liquid lens is to be made by liquid, the focusing principle of imitation human lens, thus cause that by controlling liquid generation change of shape variations in refractive index realizes focusing on and zoom.Compare with traditional lens, liquid lens have volume little, need not external mechanical devices, reaction velocity fast, do not have wearing and tearing, characteristics such as the life-span is long, cost is low.Liquid lens can be under voltage dynamic adjustments focal length controllably, have the incomparable advantage of conventional lenses.Liquid lens has begun to enter into market gradually, is applied to mobile phone, camera, digital photographies such as endoscope, medical treatment, industry, the communications field.Liquid lens mainly contains following several principle of work: 1, change lens-shape and volume by mechanical force; 2, by powering up the change Liquid Crystal Molecules Alignment; 3, principle wetting based on electricity or dielectrophoresis makes liquid generation deformation.

The electricity wetting phenomena can be described with the Young-Lippmann equation:

$\cos \mathrm{\&theta;}={\cos \mathrm{\&theta;}}_Y+\frac{{\mathrm{\&epsiv;}}_0{\mathrm{\&epsiv;}}_d}{2d{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="lv\; U"\; filenames="HSA00000208231700011.png"\; state="\{\{state\}\}">lv</figure-callout>}}}{U}^{}{}^2$

Wherein, θ applies voltage liquid-solid contact angle afterwards, θ _YInitial liquid-solid contact angle during for no-voltage, ε ₀Be permittivity of vacuum, ε _dBe the relative dielectric constant of dielectric layer, d is the thickness of dielectric layer, σ _LvBe the surface tension that liquid contacts with air, U is the voltage that applies.People such as nineteen ninety-five Gorman have realized the liquid lens based on the wetting principle of electricity for the first time.They place drop on the transparency electrode, make drop that deformation [1] take place by applying voltage.2000, on the basis of Berge and Peseux people such as Gorman experiment formerly, on electrode, covered dielectric layer.Their problem is how drop centered is fixed on [2] on the optical axis.Philips company had proposed Fluid focus technology in 2004, and conductivity water solution and oil are filled in the cylindrical container, applied voltage on bottom surface and sidewall, in liquid surface generation deformation, guaranteed that the deformation liquid level is fixed on [3] on the cylinder axis.Subsequently, Varioptic company is contained in conducting solution and oil sealing in the toot, makes liquid lens be greatly improved on optical axis stable [4].But electric wetting liquid lens multiselect wherein a kind of liquid of conductive solution conduct, experiment shows easy generation electrochemical reaction, then need on electrode, to cover insulation course if will overcome the galvanochemistry reflection, for realizing lower operating voltage, usually need very thin insulation course, this has certain difficulty in the technology preparation.

Dielectrophoresis is controlled non-conductive liquid and also can be applied in the middle of the liquid lens.Chih-Cheng Cheng and J.Andrew Yeh pour into a kind of low-k drop and with the liquid of the high-k of density in upper and lower base plate is the container of ito glass, utilize the DEP principle, focal length changes to 12mm from 34mm in voltage 0-200V scope, rises and is respectively 650ms and 300ms[5 fall time] [6].But the lens under this structure, drop can move on flat board, can not control the position of lens.Hongwen Ren and Shin-Tson Wu change focal length [7] when utilizing DEP power to make drop form lens arra.Utilize the electric field controls drop to separate like this and the formation lens, can not control the size of each drop, be unfavorable for realizing industrial standardization.Su Xu, Yeong-Jyh Lin and Shin-Tson Wu have proposed the preparation [8] of bowl type electrode DEP microlens array, but bowl type electrode preparation difficulty is easy to because a variety of causes causes non-uniform electric, and makes the liquid motion can not form lens effect.

In order to overcome the deficiency of existing liquid lens, the invention provides a kind of dielectrophoretic liquid lens arrangement, adopt two kinds of non-conductive liquid, avoided electrochemical reaction, removed the preparation of dielectric layer from.The adding of wall electrode concentrates on around the barrier field strength distribution of electric field, and the liquid surface place can obtain higher field intensity just, thereby can make the liquid motion at lower voltage.The wall electrode can also not be moved the controlling liquid position, and liquid surface is left behind the wall electrode no longer to intermediary movements.Non-conductive and the liquid of phase mixing not of two kinds of using of the present invention, its surface free energy and specific inductive capacity are compared also different with existing dielectrophoretic liquid lens, make the control voltage of lens, and lens effect has certain difference.

List of references:

[1]Christopher?B.Gorman，Hans?A.Biebuyck，George?M.Whitesides.Control?of?the?Shape?of?Liquid?Lenses?on?a?Modified?Gold?Surface?Using?an?Applied?Electrical?Potential?across?a?Self-Assembled?Monolayer.Langmuir，1995，11(6)，2242-2246.

[2]B.Berge?and?J.Peseux.Variable?focal?lens?controlled?by?an?external?voltage：An?application?of?electrowetting.Eur.Phys.J.E，2000，3，159-163.

[3]B.H.W.Hendriks，S.Kuiper，M.A.J.Van?Aa，C.A.Renders?and?T.W.Tukker.Electrowetting-Based?Variable-Focus?Lens?for?Miniature?Systems.OPTICAL?REVIEW，2005，12(3)，255-259.

[4]Lisa?Saurei，Jerome?Peseux，Frederic?Laune?and?Bruno?Berge.Tunable?liquid?lens?based?on?electrowetting?technology：principle，properties?and?applications.1-3Sept?2004，presented?at?the?10th?Annual?Micro-optics?Conference，Jena，Germany.

[5]Chih-Cheng?Cheng，C.Alex?Chang?and?J.Andrew?Yeh.Variable?focus?dielectric?liquid?droplet?lens.OPTICS?EXPRESS，2006，14(9)，4101-4106.

[6]Chih-Cheng?Cheng?and?J.Andrew?Yeh.Dielectrically?actuated?liquid?lens.OPTICSEXPRESS，2007，15(12)，7140-7145.

[7]Hongwen?Ren?and?Shin-Tson?Wu.Tunable-focus?liquid?microlens?array?using?dielectrophoretic?effect.OPTICS?EXPRESS，2008，16(4)，2646-2652.

[8]Su?Xu，Yeong-Jyh?Lin，and?Shin-Tson?Wu.Dielectric?liquid?microlens?with?well-shaped?Electrode.OPTICS?EXPRESS，2009，17(13)，10499-10505.

Summary of the invention

Technical matters: easily puncture in order to overcome electric wetting liquid lens, dielectric layer preparation difficulty, and existing dielectrophoretic liquid lens arrangement is difficult to problems such as immobile liquid body position, the invention provides a kind of dielectrophoretic liquid lens arrangement, this structure is difficult for puncturing, need not dielectric layer, effectively dynamically control focal length is realized in the immobile liquid body position.

Technical scheme: the technical solution adopted for the present invention to solve the technical problems is: this structure is made up of the liquid lens unit of arranging in length and breadth, consisting of of each liquid lens unit: on second transparency carrier, make barrier, on barrier, cover second electrode, perfusion first liquid between second electrode, second liquid covers on first liquid, cover first electrode on first transparency carrier, first electrode is positioned on second liquid.

In optimal technical scheme of the present invention, be coated with hydrophobic layer on second electrode.

In optimal technical scheme of the present invention, on first electrode, increase thin film transistor (TFT) array, the interface of first liquid and second liquid can be adjusted separately in each liquid lens unit, and promptly the focal length of liquid lens unit can be adjusted separately.

In optimal technical scheme of the present invention, the liquid lens unit is a rotational symmetry structure, and arrangement mode can be that the ranks matrix form is arranged or product word shape is arranged or honeycomb arrangement.

Beneficial effect: the invention has the beneficial effects as follows, compare, need not insulation course between first liquid and second liquid and first electrode and second electrode with traditional electrowetting lens, operating voltage is low, is difficult for puncturing, and cuts off in the middle of first electrode is positioned at, help the fixed lens optical axis position, simple in structure.

Description of drawings

Fig. 1 is a preferred embodiment of the present invention structural drawing;

Have among the above figure: 1, first transparency carrier, 2, second liquid, 3, barrier, 4, second transparency carrier, 5, first liquid, 6, first liquid level, 7, first electrode, 8, second electrode.

Embodiment

Figure 1 shows that preferred embodiment of the present invention structural drawing, mainly comprise: second transparency carrier 4, can adopt materials such as glass, transparent resin, on second transparency carrier 4, make barrier 3, can be on second transparency carrier 4 directly print metal mesh opening and form barrier 3, barrier 3 can be directly as second electrode 8, for example silver, iron, copper mesh hole etc., perhaps utilize materials such as SU-8 to form this barrier 3, on barrier 3, plate conducting film again and form second electrode 8 through uv-exposure.Barrier 3 can be made rectangle, shape such as trapezoidal, also can be the circular arc that does not have wedge angle.Perfusion first liquid 5 between barrier 3, first liquid 5 is selected the liquid that specific inductive capacity is little, surface free energy is little for use, for example dimethyl siloxane, normal hexane, isooctane, hexadecane, Decanol etc., second liquid 2 covers on first liquid 5, second liquid 2 is selected the liquid that specific inductive capacity is big, surface free energy is big for use, for example glycerine, ethylene glycol etc., also can select the liquid that specific inductive capacity is big, surface free energy is big for use by first liquid 5, and second liquid 2 is selected the liquid that specific inductive capacity is little, surface free energy is little for use.First transparency carrier 1 is the same with second transparency carrier 4, can adopt materials such as glass, transparent resin.Need to plate conducting film on first transparency carrier 1, form first electrode 7, also can select substrate for use, for example ito glass etc. with electric conductivity.First electrode 7 is covered on second liquid 2, form the simple lens structure.On second electrode 8, can also cover hydrophobic layer, for example, teflon, materials such as cytop are to reduce the hysteresis of liquid surface motion.But it is different with Electrowetting device, hydrophobic layer need not complete coating second electrode 8 herein, when between first electrode 7 and second electrode 8, applying voltage, first liquid level 6 can be moved, thereby realize lens dynamic adjustments focal length, first electrode, 7 ground connection for example, second electrode 8 connects positive voltage, produce inhomogeneous field between first electrode 7 and second electrode 8, first liquid 5 and second liquid 2 produce dielectrophoretic force, the liquid that dielectrophoretic force effect specific inductive capacity is big under inhomogeneous field, as first liquid 5, flow to the place that magnetic field gradient is big, deformation takes place in first liquid level 6 simultaneously, promptly is moved on the surface of second electrode 8.Because electric field intensity is concentrated around second electrode 8, the liquid surface place can obtain higher field intensity just, thereby liquid just can move under lower voltage.

The liquid single lens element is a rotational symmetry structure among Fig. 1, and the liquid lens array arrangement mode can be that the ranks matrix form is arranged or product word shape is arranged or honeycomb arrangement.In addition, increase thin film transistor (TFT) array on first electrode 7, the interface of first liquid and second liquid can be adjusted separately in each liquid lens unit, and promptly the focal length of liquid lens unit can be adjusted separately.

Claims (4)

1. the liquid lens of electric field force control, comprise first transparency carrier (1), second transparency carrier (4), first electrode (7), second electrode (8), first liquid (5) and second liquid (6), it is characterized in that: on described second transparency carrier (4), be manufactured with barrier (3), go up covering described second electrode (8) at described barrier (3), perfusion described first liquid (5) between second electrode (8), described second liquid (2) covers on described first liquid (5), go up covering described first electrode (7) at described first transparency carrier (1), this first electrode (7) is positioned on described second liquid (2), described first liquid (5) is non-conductive liquid, and described second liquid (2) is non-conductive liquid.

2. the liquid lens of a kind of electric field force control according to claim 1 is characterized in that: second electrode (8) is gone up and is covered hydrophobic layer.

3. the liquid lens of a kind of electric field force control according to claim 1 is characterized in that: going up at first electrode (7) increases thin film transistor (TFT) array.

4. the liquid lens of a kind of electric field force control according to claim 1, it is characterized in that: the liquid lens unit is a rotational symmetry structure, arrangement mode can be that the ranks matrix form is arranged or product word shape is arranged or honeycomb arrangement.

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