Abstract:
A piezoelectric energy harvester includes a thin film member, a support member situated to support the center or an edge of the thin film member, a piezoelectric member situated on the thin film member, and a driving member situated on the thin film member, situated to be misaligned with the support member, and configured to press the edge or the center of the thin film member. Such a design provides improved durability and functionality for a piezoelectric

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims the benefit under 35 USC 119(a) of Korean Patent Application Nos. 10-2014-0115723 filed on Sep. 1, 2014, and 10-2015-0057010 filed on Apr. 23, 2015 in the Korean Intellectual Property Office, the entire disclosures of which are incorporated herein by reference for all purposes. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The following description relates to a piezoelectric energy harvester and a wireless switch including the same. 
         [0004]    2. Description of Related Art 
         [0005]    Generally, a wireless lighting control system includes a lighting part in which a power module and a communications module are embedded, a wireless controller, a network device that connects the lighting part and the wireless controller, and an illumination sensor. 
         [0006]    However, since a separate wireless lighting controller and a separate network device are required in one approach to providing a wireless lighting control system, the structure of such a wireless lighting control system has become more complicated and manufacturing costs have increased. 
         [0007]    It may be difficult to apply a wireless lighting control system in homes, offices, or other scenarios where a wireless lighting control system would otherwise be useful, due to the issues as described above. 
       SUMMARY 
       [0008]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
         [0009]    An aspect of the present examples provides a piezoelectric energy harvester providing driving power to a wireless transmission module provided in a wireless switch. 
         [0010]    An aspect of the present examples also provides a piezoelectric energy harvester capable of having increased lifetime by significantly decreasing impacts at the time of driving. 
         [0011]    According to an aspect of the present examples, a piezoelectric energy harvester includes a thin film member, a support member situated to support the center or an edge of the thin film member, a piezoelectric member situated on the thin film member, and a driving member formed on the thin film member, situated to be misaligned with the support member, and configured to press the edge or the center of the thin film member. 
         [0012]    In one general aspect, a piezoelectric energy harvester includes a thin film member, a support member situated to support a center or an edge of the thin film member, a piezoelectric member situated on the thin film member, and a driving member situated on the thin film member, situated to be misaligned with respect to the support member, and configured to press the center or the edge of the thin film member. 
         [0013]    An edge of the support member may have a curved shape. 
         [0014]    The piezoelectric energy harvester may further include electrodes situated on the thin film member and connected to the piezoelectric member. 
         [0015]    The support member may be situated to support the center of the thin film member. 
         [0016]    The driving member may be situated to press the edge of the thin film member. 
         [0017]    The support member may be situated to support the edge of the thin film member. 
         [0018]    The driving member may be situated to press the center of the thin film member. 
         [0019]    The thin film member has a circular shape or a hemispherical shape. 
         [0020]    The thin film member may radially extend in differing directions. 
         [0021]    In another general aspect, a piezoelectric energy harvester includes thin film members, support members situated to support both ends of each of the thin film members, piezoelectric members situated on the thin film members, a connection member connecting the centers of the thin film members, and a driving member situated on the connection member and configured to press the connection member. 
         [0022]    In another general aspect, a wireless switch includes a piezoelectric energy harvester including a thin film member extending in both directions based on a support member, a piezoelectric member situated on the thin film member, and a driving member configured to press upon both ends of the thin film member, and a wireless transmission module that transmits electrical signals generated by the piezoelectric energy harvester. 
         [0023]    The wireless switch may further include a capacitor that accumulates energy generated from the piezoelectric energy harvester. 
         [0024]    The wireless switch may further include a rectifier that rectifies the electrical signals generated from the piezoelectric energy harvester. 
         [0025]    The wireless switch may further include a converter that converts the electric signals generated from the piezoelectric energy harvester into a drive voltage suitable for the wireless transmission module. 
         [0026]    Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a plan diagram of a wireless switch according to an example. 
           [0028]      FIG. 2  is a schematic configuration diagram of the wireless switch according to an example. 
           [0029]      FIGS. 3 and 4  are cross-sectional diagrams of a piezoelectric energy harvester according to an example. 
           [0030]      FIG. 5  is a perspective diagram of a piezoelectric energy harvester according to another example. 
           [0031]      FIG. 6  is a cross-sectional diagram of the piezoelectric energy harvester taken along line A-A of  FIG. 5 . 
           [0032]      FIG. 7  is a plan diagram of a piezoelectric energy harvester according to another example. 
           [0033]      FIG. 8  is a plan diagram of a piezoelectric energy harvester according to another example. 
           [0034]      FIG. 9  is a plan diagram of a piezoelectric energy harvester according to another example. 
           [0035]      FIG. 10  is a side diagram of a piezoelectric energy harvester according to another example. 
       
    
    
       [0036]    Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience. 
       DETAILED DESCRIPTION 
       [0037]    The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent to one of ordinary skill in the art. The sequences of operations described herein are merely examples, and are not limited to those set forth herein, but may be changed as will be apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Also, descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted for increased clarity and conciseness. 
         [0038]    The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided so that this disclosure will be thorough and complete, and will convey the full scope of the disclosure to one of ordinary skill in the art. 
         [0039]    A wireless switch according to an example is described with reference to  FIG. 1 . 
         [0040]    A wireless switch  10  is installed in an area in which a user is able to easily operate the wireless switch  10 . For example, the wireless switch  10  is installed on a wall surface, or the like. However, if the wireless switch  10  is installed on a wall surface, the wireless switch  10  is potentially installed on a wall that is conveniently accessible to a user. The wireless switch  10  transmits control signals operating a device disposed at a far-away distance. For example, the wireless switch  10  transmits different wireless signals depending on switching operations of the user to control an on/off operation of a device situated at a far-away distance, for example, a lighting device situated on a ceiling. However, this is only one example, and other examples include lighting devices situated in other locations. 
         [0041]    A main configuration of the wireless switch according to an example is described with reference to  FIG. 2 . 
         [0042]    The wireless switch  10 , according to the example of  FIG. 2 , includes a piezoelectric energy harvester  100 , a rectifier  200 , a capacitor  300 , a converter  400 , and a wireless transmission module  500 . 
         [0043]    Energy generated in the piezoelectric energy harvester  100  passes through the rectifier  200 , is stored in the capacitor  300 , and is converted into stable voltage by the converter  400  to thereby be transferred to the wireless transmission module  500 . 
         [0044]    The wireless transmission module  500  generates wireless communications signals depending on input signals, and RF communications signals are transferred to a wireless reception module of an external electronic device. 
         [0045]    The external electronic device is a lighting device such as a light emitting diode (LED) lamp. 
         [0046]    That is, the wireless switch, according to the example, transfers turn-on and turn-off signals to the external electronic device by using the energy generated in the piezoelectric energy harvester  100  as driving power of the wireless transmission module  500 . 
         [0047]    Therefore, by using such an approach, a wireless control system is simply and easily constructed without using a mechanically complicated configuration for connecting a switch to a lighting device, or a similar switched device, in a home. While this approach is used in the context of switching a lighting device, the approach is also relevant to other devices that are switched on and off. 
         [0048]    Hereinafter, a configuration of the piezoelectric energy harvester  100 , according to the exemplary embodiment, generating energy used as the driving power of the wireless transmission module  500  is further described with reference to the example of  FIG. 3 . 
         [0049]    The piezoelectric energy harvester  100 , according to the example, is described further with reference to  FIGS. 3 and 4 . 
         [0050]    First, referring to  FIG. 3 , the piezoelectric energy harvester  100 , according to the example, includes a thin film member  110 , a support member  120  supporting the thin film member  110 , a piezoelectric member  130  provided on the thin film member  110 , an upper electrode  140  provided on one surface of the piezoelectric member  130 , a lower electrode  150  provided on the other surface of the piezoelectric member  130 , and a driving member  160  generating a displacement in the thin film member  110 . 
         [0051]    In an example, the thin film member  110  is formed in a plate shape, has elasticity, and is supported by the support member  120 . 
         [0052]    The support member  120  is disposed on a central portion of a lower surface of the thin film member  110  to support the thin film member  110 . Therefore, when external force is applied to one side and the other side of the thin film member  110  in relation to the support member  120 , a displacement is generated in portions of the thin film member  110  to which external force is applied. 
         [0053]    The piezoelectric member  130  is provided on the thin film member  110 . Therefore, when a displacement is generated in the thin film member  110 , a displacement is also generated in the piezoelectric member  130 , and thus a piezoelectric effect generating a potential difference is generated. 
         [0054]    For example, when a displacement is generated in the thin film member  110 , a displacement is also be generated in the piezoelectric member  130  provided on the thin film member  110 , and thus a electrical polarization occurs in the piezoelectric member  130 . The voltage is generated due to the piezoelectric effect, in which an applied mechanical force leads to the generation of electrical energy. Therefore, voltage is generated in the upper electrode  140  provided on one surface of the piezoelectric member  130 , and output current generated by the voltage is used as driving power of the wireless transmission module  500 . 
         [0055]    In examples, the piezoelectric member  130  is formed of lead zirconate titanate, barium titanate (BaTiO 3 ), lead titanate (PbTiO 3 ), lithium niobate (LiNbO 3 ), silicon oxide (SiO 2 ), or another appropriate material. 
         [0056]    The lower electrode  150  is provided in order to generate a potential difference and is thus provided on the other surface of the piezoelectric member  130  so as to correspond to the upper electrode  140 . 
         [0057]    Next, referring to the example of  FIG. 4 , when the user presses the driving member  160 , an external force is applied to one side and the other side of the thin film member  110  corresponding to the driving member  160 , and thus a displacement is generated on the one side and also the other side of the thin film member  110 . 
         [0058]    When a displacement is generated on one side and the other side of the thin film member  110  with relation to the support member  120 , a displacement is also generated on one side and the other side of the piezoelectric member  130  in response to this displacement. As a result, a voltage is generated in the upper electrode  140  situated on one surface of the piezoelectric member  130 . 
         [0059]    In a case in which both sides of the thin film member  110  are displaced as described above, a displacement distance is relatively decreased, and a voltage equal to or greater than that which would occur in a case of displacing only one of both sides of the thin film member  110  is obtained, and thus impacts required to be applied to the thin film member  110  are decreased. 
         [0060]    Therefore, a lifetime of the piezoelectric energy harvester, according to the exemplary embodiment, may be increased. 
         [0061]    The voltage generated in the upper electrode  140  is used as driving power of the wireless transmission module  500 , and the wireless transmission module  500  transfers wireless communications signals to the external electronic device depending on displacement of the thin film member by the driving member. 
         [0062]    As described above, since the piezoelectric energy harvester, according to the example, decreases impacts applied thereto at the time of driving, the lifetime is increased. 
         [0063]    Further, the wireless switch, according to the example, uses the voltage generated in the energy harvester as driving power to transfer wireless communications signals to the external electronic device. 
         [0064]    Next, a piezoelectric energy harvester according to another example is described. For reference, hereinafter, components that are the same as those in the above-mentioned example are referred to by the same reference numerals and a description thereof is omitted for brevity. 
         [0065]    The piezoelectric energy harvester  100 , according to another example, is now described further with reference to the examples of  FIGS. 5 and 6 . 
         [0066]    The piezoelectric energy harvester  100 , according to the present example, is distinguished from the piezoelectric energy harvester according to the example described above by a shape of a thin film member  110 . For example, the thin film member  110  according to the present example has a hemispherical shape. 
         [0067]    The thin film member  110  having the shape as described above has excellent restoring force. 
         [0068]    As an example, the thin film member  110  is rapidly restored to an original state after a pressing operation of the user. As another example, the thin film member  110  constantly maintains an original state even after the user frequently uses the wireless switch. 
         [0069]    Therefore, it is effective to use the piezoelectric energy harvester  100  according to the present example in a place in which a switch is frequently used. 
         [0070]    The piezoelectric energy harvester  100 , according to the present example, is distinguished from the piezoelectric energy harvester according to the example described above by a shape of a support member  120 . For example, the support member  120 , according to the present example, is formed to be elongated in a ring shape along an edge of the hemispherical thin film member  110 . 
         [0071]    The support member  120  having the shape as described above is advantageous for stably supporting the hemispherical thin film member  110 . 
         [0072]    The piezoelectric energy harvester  100  configured as described above obtains a great deal of piezoelectric energy by a single switching operation. 
         [0073]    As an example, a piezoelectric member  130  generates piezoelectric energy when the thin film member  110  is deformed from a state in which the thin film member  110  is convex upward to a state in which the thin film member  110  is concave downward. In this example, the mechanical force that deforms the thin film member  110  is converted into electrical energy using the piezoelectric effect. As another example, the piezoelectric member  130  generates piezoelectric energy when the thin film member  110  is restored from the state in which the thin film member  110  is concave downward to the state in which the thin film member  110  is convex upward. 
         [0074]    Therefore, the piezoelectric energy harvester  100  according to the present example effectively accumulates a significant amount of piezoelectric energy during a single operation. 
         [0075]    A piezoelectric energy harvester according to another example is described with reference to  FIG. 7 . 
         [0076]    The piezoelectric energy harvester  100  according to the present example is distinguished from the piezoelectric energy harvesters according to the example described above by a shape of a thin film member  110  used in the example. For example, the thin film member  110  according to the present examples has a circular shape. 
         [0077]    A piezoelectric member  130  is extended from the center of the thin film member  110  in a radial direction. For example, a diameter of the thin film member  110  and a length of the piezoelectric member  130  are the same as each other. 
         [0078]    Support members  120 ,  122 ,  124 , and  126  support only portions of the thin film member  110 . For example, the support members  120 ,  122 ,  124 , and  126  are disposed at portions of the thin film member in which end portions of the piezoelectric member  130  are positioned. 
         [0079]    Since the thin film member  110  and the piezoelectric member  130  each have a plate shape, the piezoelectric energy harvester  100  configured as described above is easily manufactured. 
         [0080]    A piezoelectric energy harvester according to another example is described further with reference to the example of  FIG. 8 . 
         [0081]    The piezoelectric energy harvester  100  according to the present example is distinguished from the piezoelectric energy harvesters according to the examples described above by a shape of a thin film member  110 . 
         [0082]    The thin film member  110  according to the present example is radially extended in relation to the driving member  160 . For example, the thin film member  110  is extended in eight directions in relation to the driving member  160 . As another example, the thin film member  110  is extended in six directions in relation to the driving member  160 . 
         [0083]    In this example, support members  120  are disposed at ends of the thin film member  110 , respectively. As an example, the support members  120  are disposed on distal ends of the thin film member  110  respectively extended in several directions. In this case, the number of support members  120  is the same as the number of extended branches of the thin film member  110 . As another example, the support members  120  connects all of the distal ends of the thin film member  110  respectively extended in several directions to each other. For example, the support member  120  has a circular shape having a diameter equal to the maximum length of the thin film member  110 . 
         [0084]    Piezoelectric members  130  are formed on the thin film member  110 . As an example, the piezoelectric members  130  are separately formed on the thin film member  110  respectively extended in several directions. As another example, the piezoelectric members  130  are selectively formed on portions of the thin film member  110  respectively extended in several directions. 
         [0085]    In the piezoelectric energy harvester  100  configured as described above, since regions thereof for a plurality of piezoelectric members  130  are formed on the thin film member  110 , the number of piezoelectric members  130  formed on the thin film member  110  is easily adjusted depending on a magnitude of piezoelectric energy that is required. 
         [0086]    A piezoelectric energy harvester according to another example is described with reference to  FIG. 9 . 
         [0087]    The piezoelectric energy harvester  100  according to the present example is distinguished from the piezoelectric energy harvesters according to the examples described above by a form in which thin film members  110  and  112  are situated. In addition, the piezoelectric energy harvester  100  according to the present example is distinguished from the piezoelectric energy harvesters according to the examples described above by the fact that the piezoelectric energy harvester  100  further includes a connection member  170 . 
         [0088]    According to the present example, the thin film members  110  and  112  are situated to be spaced apart by a predetermined interval in one direction. As an example, two thin film members  110  and  112  are disposed to be spaced apart by a predetermined interval in a width direction of the thin film members  110  and  112  as illustrated in the example of  FIG. 9 . As another example, three thin film members are situated equally or similarly apart as illustrated in the example of  FIG. 9 . As another example, four or more thin film members are situate equally or similarly apart as illustrated in the example of  FIG. 9 . 
         [0089]    In an example, a pair of support members  120  and  122  are situated to support both ends of thin film members  110  and  112  separately from each other. As an example, a first support member  120  is situated to support one set of ends of the thin film members  110  and  112 . As another example, a second support member  122  is disposed to support the other set of ends of the thin film members  110  and  112 . 
         [0090]    Piezoelectric members  130  and  132  are formed on the thin film members  110  and  112  differing from each other, respectively. As an example, a first piezoelectric member  130  is formed on the thin film member  110 , and a second piezoelectric member  132  is formed on the thin film member  112 . 
         [0091]    The connection member  170  connects a plurality of thin film members  110  and  112  to each other. As an example, the connection member  170  connects two adjacent thin film members  110  and  112  to each other. As another example, the connection member  170  entirely connects three or more thin film members disposed to be spaced apart by a predetermined interval in one direction to each other. 
         [0092]    The connection member  170  is situated at bisection points of the thin film members  110  and  112 . For example, the connection member  170  connects the bisection point of the thin film member  110  and the bisection point of the thin film member  112  to each other. The connection member  170  configured as described above allows the plurality of thin film members  110  and  112  to move integrally with each other. 
         [0093]    A driving member  160  is formed on the connection member  170 . For example, the driving member  160  is formed at a bisection point of the connection member  170 . The driving member  160  configured as described above simultaneously presses the plurality of thin film members  110  and  112  through the connection member  170 . Therefore, when the user presses the driving member downward, the plurality of thin film members  110  and  112  are simultaneously bent downward, and piezoelectric energy may be generated from the piezoelectric members  130  and  132 . 
         [0094]    The piezoelectric energy harvester  100  configured as described above is effective in using a relatively small number of piezoelectric members  130  and  132 . 
         [0095]    A piezoelectric energy harvester according to another example is described with reference to  FIG. 10 . 
         [0096]    The piezoelectric energy harvester  100  according to the present example is distinguished from the piezoelectric energy harvesters according to the examples described above by a form in which thin film members  110  and  112  are disposed. In addition, the piezoelectric energy harvester  100  according to the present example is distinguished from the piezoelectric energy harvesters according to the examples described above by a form in which a connection member  170  is disposed. 
         [0097]    According to the present example, a plurality of thin film members  110  and  112  are disposed to be spaced apart by a predetermined interval in one direction. For example, two thin film members  110  and  112  are disposed to be spaced apart by a predetermined interval in a length direction of the thin film members  110  and  112  as illustrated in the example of  FIG. 10 . As another example, three thin film members are disposed equally or similarly as illustrated in the example of  FIG. 10 . 
         [0098]    The connection member  170  connects the plurality of thin film members  110  and  112  to each other. For example, the connection member  170  connects two adjacent thin film members  110  and  112  to each other. The connection member  170  is formed at a predetermined height from the thin film members  110  and  112 . To this end, both ends of the connection member  170  are extended downwards. 
         [0099]    A driving member  160  is formed on the connection member  170 . For example, the driving member  160  is formed at a bisection point of the connection member  170 . The driving member  160  configured as described above simultaneously presses the plurality of thin film members  110  and  112  through the connection member  170 . 
         [0100]    As set forth above, with the piezoelectric energy harvester according to examples, impacts applied to the driving part are decreased, and thus the lifetime is increased. 
         [0101]    Further, with the wireless switch according to examples, voltage generated in the energy harvester is used as power for generating wireless communications signals. 
         [0102]    Unless indicated otherwise, a statement that a first layer is “on” a second layer or a substrate is to be interpreted as covering both a case where the first layer directly contacts the second layer or the substrate, and a case where one or more other layers are disposed between the first layer and the second layer or the substrate. 
         [0103]    Words describing relative spatial relationships, such as “below”, “beneath”, “under”, “lower”, “bottom”, “above”, “over”, “upper”, “top”, “left”, and “right”, may be used to conveniently describe spatial relationships of one device or elements with other devices or elements. Such words are to be interpreted as encompassing a device oriented as illustrated in the drawings, and in other orientations in use or operation. For example, an example in which a device includes a second layer disposed above a first layer based on the orientation of the device illustrated in the drawings also encompasses the device when the device is flipped upside down in use or operation. 
         [0104]    While this disclosure includes specific examples, it will be apparent to one of ordinary skill in the art that various changes in form and details may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only, and not for purposes of limitation. Descriptions of features or aspects in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if the described techniques are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined in a different manner, and/or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure is defined not by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the disclosure.