1. Field of the Invention
The instant disclosure relates to a liquid lens driving method; in particular, to a driving method capable of adjusting the focus of the liquid lens.
2. Description of Related Art
Liquid lens is capable of adjusting focus, which includes two immiscible liquids. A pre-determined and axisymmetrically convex interface is formed between the two liquids, in which the convex interface resembles the optical properties of a solid lens having a convex shape.
Typically, the method to drive liquid lens commonly applies voltage on a single group of electrodes such that the liquid to liquid interface changes shape. In addition, by adjusting the value of the input voltage, the curvature of the liquid to liquid interface changes accordingly and successively adjusts the focus of the liquid lens. However, with the aforementioned driving method, the first liquid cannot accurately control the adjustable focus variables due to possible defects or particles on the substrate or deviation in voltage.
The instant disclosure provides a liquid lens driving method which adjusts the curved surface of the liquid to liquid interface between a first liquid and a second liquid. The instant method inputs voltages into specifically selected electrode or electrodes such that the base circumference of the first liquid is bounded by the inner circumference of the specifically selected electrode or electrodes. As a result, the curved surface of the first liquid can be accurately controlled, thus, providing specifically selected focus.
The liquid lens comprises two mutually immiscible and transparent liquid, a driving electrode, and a container. The curved liquid to liquid interface formed by the two mutually immiscible liquids is the axisymmetric curved surface of the liquid lens. The driving electrodes are served to provide an electric field to adjust the shape of the interface. Thus, focus of liquid lens can be adjusted. The container serves to seal the two liquids therein.
The driving electrode can be an M number of electrodes, where M is larger or equals to two. The electrodes are concentrically configured annular electrodes. A droplet of the first liquid is disposed above the driving electrodes. The driving electrodes are denoted as the first electrode being the outermost electrode, and the Mth electrode as the innermost electrode. Two adjacent electrodes have opposite polarity. When the driving voltage is inputted throughout the first electrode to the Nth electrode, base circumference of the first liquid is bounded by the inner circumference of the Nth electrode, where N is larger than or equal to 2 and is smaller or equal to M.
In summary, the instant disclosure provides a liquid lens driving method which inputs control voltages via specific voltage input modes to the corresponding driving electrodes in order to control the specific displacement of the base circumference of the first liquid to be bounded by the inner circumference of specific electrodes. The accuracy of the control can be as precise as sub-micron scale to provide precise focus.
Furthermore, by having two voltage input modes, the driving voltage and the holding voltage, fast reaction time and low power consumption are provided.
In order to further understand the instant disclosure, the following embodiments and illustrations are provided. However, the detailed description and drawings are merely illustrative of the disclosure, rather than limiting the scope being defined by the appended claims and equivalents thereof.
The driving electrode 30 is configured above the substrate 10. The quantity M of the driving electrode is a positive integer and is equal to or larger than two. In other words, the liquid lens 1 includes two or more driving electrodes 30. The driving electrodes 30 are annular in shape and concentrically configured to each other.
In
Notably, the driving electrodes 30 can be made of opaque and metallic materials such as molybdenum, chromium, copper or other conductive metal alloys. The driving electrodes 30 can also be made of transparent and conductive materials such as indium tin oxide (ITO), indium zinc oxide (IZO), or indium gallium zinc oxide (IGZO). In addition, any two adjacent and concentrically configured annular electrodes are spaced apart with a pre-determined distance of about 10 μm. However, the materials and the pre-determined distance are not limited herein.
Please refer again to
The low surface energy layer 40 is configured above the insulating layer 20. The first liquid 50 is disposed on the low surface energy layer 40 and configured directly above the driving electrode 30. As shown in
The low surface energy layer 40 can be made of materials such as poly-para-xylene or polytetrafluoroethene. When the first liquid 50 is disposed on the low surface energy layer 40, a contact angle of the first liquid 50 can be less than 20°. However, the contact angle of the first liquid 50 is not limited herein. Moreover, due to the surface properties of the low surface energy layer 40, the frictional force between the first liquid 50 and the low surface energy layer 40 is small enough such that the energy required to deform is relatively low. As a result, low driving voltage is provided. In addition, in other embodiments, the insulating layer 20 of the liquid lens 1 can also be made of low surface energy materials such as integrally forming the insulating layer 20 with the low surface energy layer 40.
Moreover, as shown in
The aforementioned disclosure, the structure of the instant embodiment, in cooperation with the illustrations according to
In the instant embodiment, liquid lens 1 includes the driving electrodes 30. As aforementioned, M annular shaped driving electrodes 30 are concentrically configured with respect to each other, where M is larger than or equal to two. As an example, the instant embodiment only provides the first electrode 32, the second electrode 34, the third electrode 36, the fourth electrode 38, and the Mth electrode to disclose the driving mechanism which drives a base circumference b1 of the first liquid 50 to various inner circumferences of the concentrically configured annular electrodes.
The controller 2 and the power supply 3 (as shown in
Notably, the liquid lens 1 driving method has two voltage input modes, one being the driving voltage V2, the other being the holding voltage V1. The driving voltage V2 drives the deformation of the first liquid 50 such that the base circumference of the first liquid 50 inwardly adjusts from the inner circumference of one concentrically configured annular electrode to the inner circumference of another concentrically configured annular electrode. In other words, the driving voltage V2 adjusts the focus from one focal length to another focal length. Moreover, in the instant embodiment, the liquid lens 1 only has one driving voltage V2. However, in other embodiments, the liquid lens 1 can have a plurality of driving voltages. For example, each of the driving electrodes 30 except for the first electrode 32, such as the second, third, or fourth electrode 34, 36, 38 can have one driving voltage individually, but is not limited herein.
The holding voltage V1 is a voltage which maintains the deformation of the first liquid 50, at which time, the holding voltage V1 is larger or equal to the minimum voltage necessary to maintain the deformation of the first liquid 50. Moreover, in the instant embodiment, the liquid lens 1 only has one holding voltage V1. However, in other embodiments, the liquid lens 1 can have a plurality of holding voltages. For example, each of the driving electrodes 30 except for the first electrode 32, such as the second, third, or fourth electrode 34, 36, 38 can have one holding voltage individually, but is not limited herein.
In the instant embodiment, the driving voltage V2 provided by the power supply 3 is larger than the holding voltage V1 of the liquid lens 1. As the driving voltage V2 become larger, the deformation of the first liquid 50 also becomes faster. In other words, the speed in which the first liquid 50 deforms depends on the value of the driving voltage V2 provided by the power supply 3.
Please refer to
Specifically in
The adjustment of the focal length of a liquid lens 1 from a long length to a short length is relative to the control of the shape of the first liquid deforming from the original shape to a convex shape. The control is explained as followed. When the controller 2 sends out a signal, the power supply 3 provides a specific voltage to the first, second, and third electrodes 32, 34, 36, in which two adjacent and concentrically arranged annular electrodes are opposite polarities, such that two adjacent and concentrically arranged annular electrodes develop one electric field therebetween. When a liquid to liquid interface between the two liquids (first and second liquids) is affected by the electric field, surface polarization charge distribution will develop proximate to the interface. Under the effect of the electric field, an electric force is developed on the interface and applied from the insulating liquid with high dielectric constant (first liquid) towards the insulating liquid with low dielectric constant (second liquid). As a result of the electric force, the shape of the first liquid 50 changes or deforms, such that the base circumference b1 of the curved surface 50b of the first liquid 50 displaces towards the center of the concentrically configured electrodes 30. Since voltage is not applied to the fourth electrode 38, no electric field is present between the third and fourth electrode 36, 38. Successively, the base circumference b1 of the curved surface 50b of the first liquid 50 displaces to the inner circumference of the third electrode 36. Focus adjustment of the liquid lens 1 is not depended on the value of the voltage provided but depended on the electrodes in which voltage are provided to. Thus, the control accuracy of the focal length of the liquid lens 1 is depended on the accuracy of the dimensions on the electrodes. The dimensions on the electrodes are the sub-micron dimensions formed by the semiconductor lithography process.
The adjustment of the focal length of a liquid lens 1 from a long length to a short length in another embodiment is relative to the control of the shape of the first liquid deforming from the original shape to a convex shape. When the controller 2 sends a signal, the power supply 3 provides a specific voltage to the second liquid and the first, second, and third electrode 32, 34, 36. At such time, the first, second, and third electrodes 32, 34, 36 have the same polarity and while having polarity opposite the second liquid. An interface between the second liquid and each of the first, second, and third electrodes 32, 34, 36 develops an electric field. When the charged ions proximate to the interface of the second liquid is affected by the electric field, the first liquid 50 will begin to deform such that the base circumference b1 of the curved surface 50b of the first liquid 50 displaces inwardly towards the center of the concentrically configured electrodes 30. Since voltage is not provided to the fourth electrode 38, an electric field is not developed between the second liquid and fourth electrode 38. Successively, the base circumference b1 of the curved surface 50b of the first liquid 50 will be displaced to the inner circumference of the third electrode 36. Focus adjustment of the liquid lens 1 is not depended on the value of the voltage provided but depended on the electrodes in which voltage are provided to. Thus, the control accuracy of the liquid lens 1 is depended on the accuracy of the dimensions on the electrodes. The dimensions on the electrodes are the sub-micron dimensions are accurately formed by the semiconductor lithography process.
Please refer to
The base circumference b1 of the curved surface 50b of the first liquid is first affected by the electric field E1 and is displaced to the second electrode 34, and then further affected by another electric field E2 and displaced to the third electrode 36. Since no electric field is present between the third and fourth electrode 36, 38, no forces are applied onto the curved surface of the liquid bead 50b, thus, the curved surface 50b of the first liquid 50 cease to displace towards the center of the concentrically configured electrodes 30.
Similarly, to displace the base circumference b1 of the curved surface 50b of the first liquid 50 to the second electrode 34 the power supply 3 is required to provide one driving voltage V2 to the first electrode 32 and the second electrode 34 such that the electric field E1 is present between the first and second electrode 32, 34. As a result, the base circumference b1 of the curved surface 50b of the first liquid 50 displaces to the second electrode 34 under the effect of the electric field E1.
Please refer to
Moreover, two modes can be taken to maintain the curved surface 50b of the first liquid 50 at a particular electrode. Please refer to
In the instant embodiment as shown in
The aforementioned discloses the curved surface 50b of the first liquid 50 deforms and displaces from the first electrode 32 towards the electrodes 30 proximate to the center of the concentric electrodes 30. The following discloses the curved surface 50b of the first liquid 50 deforms and displaces from the electrodes 30 proximate to the center of the concentric electrodes 30 towards the first electrode 32. In other words, the control of the focal length of the liquid lens 1 adjusting from short to long or returning to the original focal length is disclosed as followed.
More specifically, if after the curved surface 50b of the first liquid 50 is on the Nth electrode, the holding voltage V1 is not provided to the Nth electrode, but rather the holding voltage V1 is only provided throughout all electrodes from the first to the Lth electrode, the electric field EN between the Nth electrode and the N−1th electrode vanishes. At such time, the force on the interface of the curved surface 50b of the first liquid 50 similarly vanishes. Under the influence of surface tension, the curved surface 50b of the first liquid 50 outwardly displaces. In other words, the base circumference b1 of the curved surface 50b of the first liquid 50 outwardly expands towards the direction of the Lth electrode. Under the influence of the force between the Lth electrode and the L−1th electrode, the base circumference b1 of the curved surface 50b of the first liquid 50 cease to expand at the Lth electrode, where the Lth electrode is any one electrode between the first and the Nth electrode and L is larger than two and smaller than N.
Please refer to
However, as the base circumference b1 of the curved surface 50b of the first liquid 50 outwardly expands to the inner circumference of the fourth electrode 38, the base circumference b1 of the curved surface 50b of the first liquid 50 ceases to displace due to the electric fields E3, E2, E1 respectively developed between the fourth and third electrodes 36, 38, the third and second electrodes 36, 34, and the second and first electrodes 34, 32. At such time, the electric fields developed by holding voltage V1 act upon the interface of the first liquid 50 such that the base circumference b1 of the curved surface 50b of the first liquid 50 ceases to displace (as shown in
Similarly, if voltage is not provided, by the power supply 3 initiated by a signal from the controller 2, to the fourth and third electrodes 38, 36, the curved surface 50b of the first liquid 50 is only affected and displaced by the electric field E1 developed between the first and the second electrode 32, 34. Thus, the curved surface 50b of the first liquid 50 is displaced to the second electrode 34. If the controller 2 sends a signal to the power supply 3 such that no voltage is provided to any of the electrodes 30, the curved surface 50b of the first liquid 50 returns to the pre-deformed state.
Furthermore, holding voltage V1 can be provided only to the Lth and the L−1th electrode such that the curved surface 50b of the first liquid 50 is bounded by the Lth electrode. As shown in
The disclosure above describes the first embodiment of the liquid lens 1 driving method while the following disclosure describes the second embodiment of the liquid lens 1 driving method.
Please refer to
Please refer to
Since the first liquid 50′ maintains at the N′th electrode, the first liquid 50′ is only effected by the electric field EN′ developed between the N′th electrode and the second 60′. As a result, the holding voltage V1′ can only be provided to the N′th electrode and the second 60′ as shown in
Moreover,
In summary, in the liquid lens 1 driving method of the instant disclosure, when the controller 2 sends signal to the power supply 3 to provide one driving voltage V2 to the first to the Nth electrode (ex. the fourth electrode), the base circumference b1 of the curved surface 50b of the first liquid 50 deforms to the Nth electrode (ex. the fourth electrode). The deformation of the first liquid 50 depends on the positions of the concentrically configured annular electrodes provided with input voltages. The driving electrodes 30 of the liquid lens 1 has M concentrically configured annular electrodes such that the first liquid 50 can deform and be bounded by M−1 positions. In other words, the liquid lens 1 has M−1 focus value or values. Notably, N is a positive integer, and N is larger than two and less than M.
Moreover, when the base circumference b1 of the curved surface 50b of the first liquid 50 deforms to the Nth electrode, the controller 2 sends a signal to the power supply 3 to provide driving voltage V2 only to the Nth and N−1th electrodes in order to reduce power consumption. When the curved surface 50b of the first liquid 50 deforms to the Nth electrode, the controller 2 can send a signal to the power supply 3 to not provide voltage to the Nth electrode. As a result, the base circumference b1 of the curved surface 50b of the first liquid 50 displaces from the Nth to the N−1th electrode.
Furthermore, liquid lens 1 can have one or more holding voltage V1. When the liquid lens 1 has one holding voltage V1, the driving voltage V2 requires to be larger or equal voltage to the holding voltage V1. When the liquid lens 1 has a plurality of holding voltages V1, all electrodes 30 other than the first electrode 32 has one holding voltage V1. When the curved surface 50b of the first liquid 50 deforms to the Nth electrode, the driving voltage requires to be larger or equal to the holding voltage of the Nth electrode. In addition, when the driving voltage is larger than the holding voltage, the driving voltage is reduced to the holding voltage after the curved surface 50b of the first liquid 50 deforms in order to reduce power consumption.
Notably, the larger the driving voltage, the shorter amount of time is required for the curved surface 50b of the first liquid 50 to displace to the desired electrode 30. In other words, the curved surface 50b of the first liquid 50 reaches the desired focus in a shorter amount time, thus, reduces the time for the liquid lens to adjust focus.
The embodiments are explained through data. According to the relationship between the value of the voltage and the relative reaction time in an actual measurement of data during the driving of the liquid lens, when the input voltage is substantially equals to the minimum driving voltage of 30 volts, which bounds the curved surface 50b of the first liquid 50 at the inner circumference of one of the particular concentrically configured annular electrodes, the required reaction time is about 216 milliseconds. When the driving voltage is increased to 40 volts, the required reaction time is reduced to 88 milliseconds. When the driving voltage is increased to 60 volts, the reaction time is further reduced to 40 milliseconds, which is about one fifth of the time of the driving voltage at 30 volts.
Comparing the liquid lens 1 driving method as aforementioned to the conventional method, the liquid lens 1 driving method of the instant embodiment is similar to the digital lens. However, the liquid lens 1 driving method of the instant embodiment depends on the position of the electric field formed between the Mth and the M−1th concentrically configured annular electrodes to control the deformation of the first liquid 50, and thus, various focal lengths are provided. As a result, the liquid lens 1 driving method of the instant embodiment not only expedite the deformation of the liquid lens 50, but also provides more accurate control of the deformation of the liquid lens 50 comparing to the conventional method, and thusly, relatively more precise focus.
In summary, the instant disclosure provides a liquid lens 1 driving method inputs control voltages via specific voltage input modes to the corresponding driving electrodes in order to control focus of the liquid lens. When the first liquid is driven to deform, the controller can send a signal to the power supply in order to provide the driving voltage throughout each electrode from the first to the Nth electrode. With the driving voltage provided, the first liquid deforms such that the base circumference b1 of the first liquid is bounded by the inner circumference of various concentrically configured annular electrodes in order to provide various focus. Moreover, the driving voltage must be larger than or equal to the holding voltage. The larger the difference between the driving voltage and the holding voltage, the faster the first liquid reaches the desired focus, thus, reducing the adjustment time of the liquid lens.
The figures and descriptions supra set forth illustrated the preferred embodiments of the instant disclosure; however, the characteristics of the instant disclosure are by no means restricted thereto. All changes, alternations, combinations or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the instant disclosure delineated by the following claims.
Number | Date | Country | Kind |
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102112705 | Apr 2013 | TW | national |