An electrowetting driven liquid lens

Abstract

An electrowetting driven liquid lens comprises a dielectric electrowetting wire coil (1), a transparent upper cover sheet (2), a lower cover sheet (3) and a shell (4); the dielectric electrowetting coil (1) is formed by a dielectric electrowetting wire (7) formed by a conductive wire core (8) wrapped with an insulating layer (9) and tightly wound in an annular shape, a viscose coating layer (5) is provided on the outside of the coil to make it a container capable of containing liquid, and a shell (4) is provided on the outside of the coating layer to play a protective role; the internal space of the coil is sealed by the transparent upper cover sheet (2) and the lower cover sheet (3) to form a lens cavity (6), in which transparent conductive liquid and insulating liquid with different refractive indices and immiscible with each other are stored as lens materials, and the curved interface between the liquids plays a lens role, and the shape of the curved interface is changed through the electrowetting driving effect to achieve optical zoom. A hydrophobic layer (10) can be coated on the outside of the insulating layer (9) wrapped around the dielectric electrowetting wire (7), and the insulating layer (9) and the hydrophobic layer (10) can also be combined into one, and the hydrophobic layer can also be coated after the dielectric electrowetting coil (1) is manufactured. The liquids stored in the lens cavity (4) may be three or more liquids.

Description

Technical Field

[0001] The invention patent relates to a novel coil-type electro-wetting driven liquid lens structure and its working principle, and belongs to the technical field of photoelectric imaging, photoelectric sensing and optical information processing devices. Background Art

[0002] Optical zoom lenses are usually composed of multiple groups of independent convex / concave lenses, some of which are fixed and some of which can slide back and forth along the optical axis. Complex zoom lenses can contain up to thirty independent lenses and multiple moving parts. Mobile phone cameras are developing towards miniaturization, specialization, and intelligence. Liquid variable lenses, as a key component that can integrate multiple cameras into a single camera, have broad market prospects. Liquid zoom lenses do not require mechanical movement, but achieve zoom by changing the shape of the liquid. They have many advantages such as compact structure, flexible control, low manufacturing cost, no mechanical wear, and easy integration. They are expected to end the development disputes of multi-camera simulated optical zoom in mobile phone lenses.

[0003] Liquid zoom lens based on electrowetting effect uses an external voltage to adjust the curvature of the liquid's curved interface, thereby changing the focal length of the lens. This type of lens has a compact structure and a large focal length adjustment range. Typical liquid variable lenses include FluidFocus released by Philips of the Netherlands and the small liquid zoom lens released by Varioptic of France. The zoom of these lenses uses an electrowetting drive method to change the curvature of the liquid's curved interface to adjust the focal length. This technology uses flowing liquid as a zoom lens component, which has many advantages over the current mechanical zoom method. However, these small zoom liquid lenses using electronic control methods have complex structures, expensive materials, and low yields. There are no mature commercial products in China. Summary of the invention

[0004] The purpose of the present invention is to provide a coil-type electro-humidification driven liquid lens structure, simplify the manufacturing process, improve the production technology, and solve the production cost problem of the liquid lens.

[0005] The present invention proposes a coil-type electrowetting driven liquid lens structure, see Figure 1 , including a dielectric wet coil 1, a transparent upper cover sheet 2 and a lower cover sheet 3 and a shell 4; wherein the dielectric wet coil 1 is formed by a dielectric wet wire 7 tightly wound in a ring shape to form a cavity, a viscose coating layer 5 is provided on the outside of the coil to enable the cavity inside the coil 1 to contain liquid, and a shell 4 is provided outside the coating layer to protect the coil from external influences. Of course, in order to reduce the volume, the shell can sometimes be omitted; the core component dielectric wet wire 7 is formed by a conductive wire core 8 wrapped with an insulating layer 9, and a hydrophobic layer 10 can be coated on the outside of the insulating layer 9 to improve the hydrophobicity of the outer surface of the wire core. Sometimes the insulating layer and the hydrophobic layer are combined into one, see Figure 2Therefore, the dielectric electrowetting coil contains two important elements of the electrowetting effect - the conductive layer and the insulating hydrophobic layer. Of course, the hydrophobic layer can also be coated and set in its inner cavity after the coil is formed;

[0006] The cavity space inside the coil is sealed by a transparent upper cover sheet 2 and a lower cover sheet 3 to form a lens cavity 6, and transparent conductive liquid and insulating liquid having different refractive indices and being immiscible with each other are stored in the cavity as lens materials.

[0007] Regarding the arrangement of electrodes, they are divided into common electrodes and control electrodes: the surfaces of the upper cover sheet 2 and the lower cover sheet 3 in contact with the conductive liquid are provided with a transparent conductive layer as a common electrode, or other conductive materials are provided in contact with the conductive liquid and serve as a common electrode. When the shell 4 is made of a conductive material, sometimes the shell directly contacts the conductive liquid and serves as a common electrode; the tap of the dielectric electrowetting coil 1 serves as a control electrode. The shape of the lens cavity can be a circular tube, a conical tube, a double conical tube, a hyperbolic tube, a wavy tube, etc. When used as a double liquid lens, the shape of the lens cavity is preferably a circular tube or a conical tube, see Figure 1 and Figure 3 When the liquid stored in the lens cavity can be three or more, the cavity shape can be preferably a double cone tube (see Figure 4 ), double curved tube or corrugated tube (see Figure 5 ).

[0008] The curved interface formed by the contact between the conductive liquid and the insulating liquid acts as a lens. When a voltage is applied between the common electrode and the control electrode, the interfacial tension between the conductive liquid and the dielectric electrowetting coil is reduced due to the electrowetting effect, thereby changing the shape of the curved interface to achieve optical zoom.

[0009] Beneficial effects: According to the above description, the present invention has the following characteristics:

[0010] This patent combines coil forming technology with modern optical technology to design a coil-type electrohumidification driven liquid lens structure, which has important economic and technical value. The device designed by the invention has the advantages of simple structure, easy production and low cost.

[0011] The innovation lies in:

[0012] 1) Invented dielectric electrowetting wire, then applied this wire to the construction of liquid variable focus lens products and provided electrowetting effect drive. The core component of the traditional liquid variable focus lens, the insulating dielectric layer that provides the electrowetting effect, was transformed into wire core processing with mature production technology, which greatly simplified the production process and improved the yield rate.

[0013] 2) Since the zoom driving force of the variable liquid lens of the present invention comes from the electrowetting effect between the dielectric electrowetting line and the conductive liquid, and has nothing to do with the shape of the lens cavity, a variable focus liquid lens of any shape can be constructed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The schematic diagram of the coil-type electrowetting driven liquid lens structure is shown in the figure. In the figure, there are 1-dielectric electrowetting coil, 2-upper cover sheet, 3-lower cover sheet, 4-housing, 5-adhesive, 6-lens cavity, and 7-dielectric electrowetting wire.

[0015] Figure 2 It is a schematic diagram of the dielectric electric wet wire structure, in which there are 8-conductive wire core, 9-insulating layer, and 10-hydrophobic layer;

[0016] Figure 3 It is a schematic diagram of a lens cavity having a conical structure;

[0017] Figure 4 It is a schematic diagram of a lens cavity having a double-conical structure.

[0018] Figure 5 It is a schematic diagram of a lens cavity having a wavy structure. DETAILED DESCRIPTION

[0019] The embodiment of the present application provides a coil-type electro-wetting driven liquid lens structure, which can be widely used in lens systems that require optical zoom.

[0020] For details, see Figure 1 The present invention comprises a dielectric wet coil 1, a transparent upper cover sheet 2 and a lower cover sheet 3 and a shell 4; wherein the dielectric wet coil 1 is formed by a dielectric wet wire 7 tightly wound in a ring shape to form a cavity, a viscose coating layer 5 is provided on the outside of the coil to enable the cavity inside the coil 1 to contain liquid, and a shell 4 is provided on the outside of the coating layer to protect the coil from external influences; the core component dielectric wet wire 7 is formed by a conductive wire core 8 wrapped with an insulating layer 9, and a hydrophobic layer 10 can be coated on the outside of the insulating layer 9 to improve the hydrophobicity of the outer surface of the wire core, and sometimes the insulating layer and the hydrophobic layer are combined into one, see Figure 2 Therefore, the dielectric electrowetting coil contains two important elements of the electrowetting effect - the conductive layer and the insulating hydrophobic layer. Of course, the hydrophobic layer can also be coated and set in its inner cavity after the coil is formed;

[0021] The cavity space inside the coil is sealed by a transparent upper cover sheet 2 and a lower cover sheet 3 to form a lens cavity 6, and transparent conductive liquid and insulating liquid having different refractive indices and being immiscible with each other are stored in the cavity as lens materials.

[0022] The curved interface formed by the contact between the conductive liquid and the insulating liquid acts as a lens. When a voltage is applied between the common electrode and the control electrode, the interfacial tension between the conductive liquid and the dielectric electrowetting coil is reduced due to the electrowetting effect, thereby changing the shape of the curved interface to achieve optical zoom.

[0023] Regarding the arrangement of electrodes, they are divided into common electrodes and control electrodes: the surfaces of the upper cover sheet 2 and the lower cover sheet 3 in contact with the conductive liquid are provided with a transparent conductive layer as a common electrode, or other conductive materials are provided in contact with the conductive liquid and serve as a common electrode. When the shell 4 is made of a conductive material, sometimes the shell directly contacts the conductive liquid and serves as a common electrode; the tap of the dielectric electrowetting coil 1 serves as a control electrode. The shape of the lens cavity can be a circular tube, a conical tube, a double conical tube, a hyperbolic tube, a wavy tube, etc. When used as a double liquid lens, the shape of the lens cavity is preferably a circular tube or a conical tube, see Figure 1 and Figure 3 When the liquid stored in the lens cavity can be three or more, the cavity shape can be preferably a double cone tube (see Figure 4 ), double curved tube or corrugated tube (see Figure 5 ).

[0024] When the lens medium is a conductive liquid + an insulating liquid forming a single curved interface, the control electrode is a coil tap, and one of the taps can be selected as an electrode, or two taps can be connected in parallel to form one electrode.

[0025] The following introduces the common electrode setting in three cases.

[0026] Solution 1: A transparent conductive layer is provided on the surface of the upper cover sheet or the lower cover sheet that contacts the conductive liquid, serving as a common electrode.

[0027] Solution 2: To minimize the reflection loss of light by the upper and lower cover sheets, no transparent conductive layer is provided on the surface of the upper and lower cover sheets. In this case, other conductive materials may be provided between the conductive liquid and the sealing cover sheet to contact the conductive liquid and serve as a common electrode.

[0028] Solution three, when the shell is made of conductive material, the conductive liquid is in direct contact with the conductive shell as a common electrode.

[0029] When the lens medium is a conductive liquid + insulating liquid + conductive liquid forming a three-liquid double curved interface, the common electrode is a coil tap, and one of the taps can be selected as an electrode, or two taps can be connected in parallel as one electrode. At this time, the surfaces of the upper cover sheet and the lower cover sheet in contact with the conductive liquid are both provided with a transparent conductive layer, which serves as the upper and lower control electrodes, and different voltages are applied to independently control the upper curved interface and the lower curved interface of the three-liquid lens.

[0030] In Example 1, a cylindrical or conical frame is first made, and the coil 1 is made using a conventional coil close-packed winding method. After completion, it is removed from the frame, and adhesive is applied to the outer periphery to make the coil 1 into a container wall with liquid-tight side walls, which can then be installed in the housing. The core 8 of the dielectric electric wet wire is preferably but not limited to a soft metal thin conductive wire, such as copper wire, silver wire, gold wire, aluminum wire, iron wire or tantalum, niobium, etc., and can also be made of non-metallic conductive materials such as conductive silicone rubber; according to the different inner diameters of the circular (conical) cylinder, cores of different core diameters can be selected, ranging from micrometers to millimeters; the outer periphery of the core is evaporated or coated with micrometer-level parylene as an insulating layer, and the typical value can be 1-10 micrometers. Insulating dielectric materials commonly used in capacitors can also be selected, such as tantalum oxide (niobium), aluminum oxide and other high dielectric constant materials to reduce the driving voltage; the hydrophobic layer mainly plays a hydrophobic modification role, so a polytetrafluoroethylene polymer material coating below the micrometer level or even the nanometer level is used to achieve it, and a surface microstructure can also be made on the outside of the insulating layer to improve the hydrophobicity. The hydrophobic layer can also be coated separately after the electric wet coil is set. The shell can be made of metal or non-metal by casting as needed.

[0031] The transparent upper and lower covers are made of high-performance thin glass sheets, and the conductive layer of the transparent cover can be realized by an ITO layer prepared by a vacuum coating method. The insulating liquid is dodecane bromide, and the conductive liquid is a lithium chloride aqueous solution with the same density as dodecane to eliminate the influence of gravity.

[0032] Embodiment 2: The dielectric wet coil 1 can be formed by using a copper (or other metal) rod drawn by a wire drawing machine to form a coil by wrapping the copper (or other metal) wire through a polyamide resin insulation layer and a self-adhesive insulation layer. After the outer periphery of the coil 1 is coated with adhesive, if the device strength is sufficient, the outer shell can be omitted to compress the device volume.

[0033] Embodiment 3, since the zoom driving force of the variable liquid lens of the present invention comes from the electrowetting effect between the dielectric electrowetting line 7 and the conductive liquid, and has nothing to do with the shape of the lens cavity, an optical variable focus lens with any cavity shape can be constructed, such as a rectangular cavity, a cylindrical cavity, a conical cavity, a biconical cavity, a hyperbolic cavity, a wavy cavity, and any combination of the above shapes; for a double liquid lens, that is, the lens cavity is filled with two immiscible liquids, namely a conductive liquid and an insulating liquid, preferably a lens cavity in the shape of a conical cavity, which is convenient for stabilizing the optical axis of the lens, and the two electrodes are respectively the tap of the dielectric electrowetting line 7 and the electrode led out of the conductive liquid through the glass conductive layer or other means; for a three-liquid lens, that is, the lens cavity is filled with three immiscible liquids, namely a conductive liquid, an insulating liquid and a conductive liquid in order from top to bottom, preferably a lens cavity in the shape of a biconical cavity, see the attached Figure 4, which is convenient for stabilizing the optical axis of the lens. The common electrode is a tap of the dielectric wet line 7, and the control electrodes are electrodes drawn out of two conductive liquids through a glass conductive layer or other means; for a multi-liquid lens, that is, the lens cavity is filled with three or more liquids that are immiscible with each other, see Figure 5 , the contact with the upper cover and the lower cover is set as a conductive liquid, the electrowetting effect can only drive two curved interfaces, such as interface 1 and interface 2, and the other curved interfaces are used as fixed lenses. A wave-shaped lens cavity or a combination of a double cone cavity, a hyperbolic cavity, etc. can be selected. The electrode control scheme is the same as the three liquid lenses; the upper and lower cover plates are selected from chemically strengthened optical glass or other similar materials used in the production of mobile phone screens, such as sodium silicate glass materials, Corning Gorilla Glass, or organic glass for making OLEDs. Using tantalum pentoxide (Ta2O5) with a dielectric constant of up to 20 or niobium pentoxide (Nb2O5) with a relative dielectric constant of 35-50 as the insulating dielectric layer of the dielectric electrowetting line can greatly reduce the device driving voltage.

Claims

1. An electrowetting driven liquid lens, characterized in that: The coil-type electrowetting driven liquid lens comprises a dielectric electrowetting coil (1), a transparent upper cover sheet (2), a transparent lower cover sheet (3) and a shell (4); the dielectric electrowetting coil (1) is formed by tightly winding a dielectric electrowetting wire (7) in a ring shape, a viscose coating layer (5) is provided on the outside of the coil, and a shell (4) is provided on the outside of the coating layer; the internal space of the coil is sealed by the transparent upper cover sheet (2) and the lower cover sheet (3) to form a lens cavity (6), in which transparent conductive liquid and insulating liquid with different refractive indices and immiscible with each other are stored as lens materials, and the curved interface between the liquids acts as a lens, and the shape of the curved interface is changed through the electrowetting driven effect to achieve optical zoom; The dielectric wet wire (7) is formed by a conductive wire core (8) wrapped with an insulating layer (9); The dielectric electric wet wire (7) is coated with a hydrophobic layer (10) on the outer surface of the insulating layer (9); or the insulating layer (9) and the hydrophobic layer (10) are combined into one; The surfaces of the upper cover sheet (2) and the lower cover sheet (3) in contact with the conductive liquid are provided with a transparent conductive layer as a common electrode; or other conductive materials are provided in contact with the conductive liquid as a common electrode; or when the shell (4) is made of a conductive material, the shell is directly in contact with the conductive liquid as a common electrode; The tap of the dielectric wet coil (1) serves as a control electrode.

2. The electrowetting driven liquid lens according to claim 1, characterized in that: When the dielectric wet coil (1) has a certain hardness, the outer shell (4) is discarded.

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