Patent Publication Number: US-2013241211-A1

Title: Power generator, electronic device, and power generating device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a Continuation application of International Application No. PCT/JP20121050342, filed Jan. 11, 2012, which claims priority to Japanese Patent Application No. 2011-003966, filed on Jan. 12, 2011, Japanese Patent Application No. 2011-274324, filed on Dec. 15, 2011, and Japanese Patent Application No. 2012-000181, filed on Jan. 4, 2012. The contents of the aforementioned applications are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to a power generator, an electronic device, and a power-generating device. 
     2. Description of Related Art 
     In the related art, a technique is known in which a piezoelectric material is deflected to generate power (for example, see Japanese Unexamined Patent Application, First Publication No. 2010-230440). 
     As a piezoelectric body of the power-generating device, for example, ceramics formed in a rod shape is used. 
     SUMMARY 
     However, in the technique disclosed in Japanese Unexamined Patent Application, First Publication No. 2010-230440, there is a problem in that power generation is not possible when the piezoelectric material is not vibrating. Since ceramics, which is one of the piezoelectric materials, has high impedance, there is a problem in that a small amount of power is obtained. Furthermore, since ceramics is a brittle material, there is a problem in that it is not suitable for reduction in size. 
     An aspect of the invention provides a technique which generates power by vibration, continuously generates power even when there is no vibration, obtains a large amount of power, and is suitable for reduction in size. 
     When a piezoelectric body is formed in a rod shape, there is a problem in that it is not suitable for reduction in size in one direction. That is, ceramics is a brittle material and thus vulnerable to impact or the like, and there is a problem in that it is difficult to produce a complicated shape, such as a coil shape, so as to increase the amount of deflection with a limited volume and to increase the amount of power generation. 
     Another aspect of the invention provides a power-generating device and an electronic device suitable for reduction in size. 
     A power generator according to a first aspect of the invention includes a spring, and a power-generating unit which is formed using a magnetostrictive material, wherein the power-generating unit generates power by force stored in the spring when force is not applied to the magnetostrictive material. 
     In the power generator, the spring may store force by vibration, operation of an operator, or wind power. 
     An electronic device according to another aspect of the invention includes the above-described power generator. 
     A second aspect of the invention provides a power-generating device including a vibrating portion which is formed to have a spiral shape in one direction and includes a magnetostrictive material, a vibration transmission portion which transmits vibration to the vibrating portion, and a coil portion which generates an induced current according to change in magnetic flux density caused by the vibration of the vibrating portion. 
     Another aspect of the invention provides an electronic device including a processing unit which performs predetermined processing, a power supply unit which supplies power to the processing unit, and a power-generating unit which generates at least a part of the power to be supplied from the power supply unit to the processing unit, wherein the power-generating device according to the first aspect of the invention is used as the power-generating unit. 
     According to the aspect of the invention, continuous power generation becomes possible even when a housing is not vibrating. For example, it is possible to obtain a large amount of power compared to a piezoelectric element, and it is more robust and more suitable for reduction in size. 
     According to another aspect of the invention, it is possible to provide a power-generating device and an electronic device suitable for reduction in size. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a configuration diagram of an electronic device according to a first embodiment of the invention. 
         FIG. 1B  is a configuration diagram of the electronic device according to the first embodiment of the invention. 
         FIG. 2  is a schematic view of a power-generating unit according to the first embodiment of the invention. 
         FIG. 3A  is a schematic view of a power-generating unit according to the first embodiment of the invention. 
         FIG. 3B  is a schematic view of the power-generating unit according to the first embodiment of the invention. 
         FIG. 4  is a block diagram showing the schematic configuration of an electronic device according to a second embodiment of the invention. 
         FIG. 5  is a schematic perspective view showing the configuration of a power-generating unit according to the second embodiment of the invention. 
         FIG. 6  is a diagram showing the configuration of a part of the power-generating unit according to the second embodiment of the invention. 
         FIG. 7  is a diagram showing another configuration of the power-generating unit according to the second embodiment of the invention. 
         FIG. 8  is a diagram showing another configuration of the power-generating unit according to the second embodiment of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     Hereinafter, a first embodiment of the invention will be described referring to the drawings.  FIG. 1A  is a schematic functional configuration diagram of an electronic device  1  according to the first embodiment of the invention.  FIG. 1B  is a detailed configuration diagram of a power generator  10  shown in  FIG. 1A .  FIG. 2  is a schematic view of a power-generating unit  14 . 
     An electronic device  1  is, for example, a portable information device, and as shown in  FIG. 1A , includes a power generator  10 , a power supply unit (secondary battery)  20  which stores power generated by the power generator  10 , and a processing unit (load circuit)  30  which is driven with power supplied from the power supply unit  20 . 
     The processing unit  30  includes an input unit  32 , a control unit  34 , a storage unit  36 , and an output unit  38 . The input unit  32  inputs information from the outside. While the input unit  32  differs depending on the type of the electronic device  1 , for example, a receiving unit which receives information transmitted from the outside, an operation-receiving unit which receives an input operation by an operator, a detection unit (for example, a magnetic sensor) which detects an external environment, or the like corresponds to the input unit  32 . 
     The control unit  34  performs various kinds of processing based on information input by the input unit  32 , information stored in the storage unit  36 , or the like. The storage unit  36  stores information input by the input unit  32 , information (for example, a control program) which is used for processing by the control unit  34 , information (for example, output information) generated by the control unit  34 , or the like. 
     The output unit  38  outputs information to the outside. While the output unit  38  differs depending on the type of the electronic device  1 , for example, a transmitting unit which transmits information to the outside, a presentation unit (for example, a display, a lamp, or a speaker) which presents information to the operator, a driving unit which drives (for example, a vibration function) the housing (hereinafter, referred to as a “housing”) of the electronic device  1 , or the like corresponds to the output unit  38 . 
     The power generator  10  includes at least a spring  12  and the power-generating unit  14 , and as shown in  FIG. 1B , may include a capacitor  16  in addition to the spring  12  and the power-generating unit  14 . 
     The spring  12  stores force (elastic energy) by the vibration of the housing. For example, the spring  12  stores force by vibration when the user consciously shakes the housing, vibration when a user carries the housing, driving (for example, a vibration function) by processing of the processing unit  30 , or the like. 
     The spring  12  may store force from other than vibration. For example, the spring  12  may store force by operation of the operator, wind power, or the like. When wind power is used, a windmill (fan) may be used. 
     As the operation of the operator, an operation to directly store force in the spring  12  (for example, an operation to consciously wind up the spring), or an operation to indirectly store force in the spring  12  may be used. An example of the operation to indirectly store force in the spring  12  is an operation to hold down a button arranged in the housing. That is, the spring  12  stores force when a button is held down. 
     Force stored in the spring  12  is used as force which deforms (vibrates, deflects) the magnetostrictive material of the power-generating unit  14  (details will be described below). 
     As shown in  FIG. 2 , the power-generating unit  14  has magnetostrictive materials  50  and a coil  52 .  FIG. 2  is a sectional view in which the magnetostrictive materials  50  in the coil  52  are shown. In  FIG. 2 , although two magnetostrictive materials  50  are shown, the power-generating unit  14  may have one or three or more magnetostrictive materials  50  (the same applies to a power-generating unit  114  of  FIG. 3  described below). Although  FIG. 2  shows the coil  52  wound around the two magnetostrictive materials  50  together, as a way of winding the coil  52 , the coil  52  may be wound around each magnetostrictive material  50 . 
     The magnetostrictive materials  50  of the power-generating unit  14  are deformed by force (bending force, pulling force, stretching force), and cause change in magnetic flux density (inverse magnetostriction effect). The coil  52  of the power-generating unit  14  generates an induced current according to change in magnetic flux density. That is, when force is applied to the magnetostrictive materials  50  (that is, when vibration or deflection is given), the power-generating unit  14  changes force to be applied to the magnetostrictive materials  50  to electricity, that is, generates power (obtains electric energy). For example, the power-generating unit  14  generates power when force is applied to the magnetostrictive materials  50  by the vibration of the housing. 
     When the magnetostrictive materials  50  are used, for example, the following effects can be obtained. As the magnetostrictive materials  50 , a Fe—Ga-based material (iron-gallium alloy) is preferably used.
         While a small amount of power is obtained by a load in a piezoelectric element which has capacitive impedance (high impedance), since the magnetostrictive materials  50  have low impedance, a large amount of power is obtained by a load (matching with the load is satisfactory).   While a piezoelectric element using ceramics (brittle material) is unsuitable for processing, since the magnetostrictive materials  50  are hard to break and are ductile, mechanical processing is possible. Accordingly, since extreme reduction in size (above several millimeters) is possible, it is useful for mounting in a compact electronic device (for example, a portable music player, a mobile communication device, or a human body-implantable medical device).   The magnetostrictive materials  50  have the amount of power generation proportional to the size of the material.   While a piezoelectric element has low efficiency (piezoelectric transverse effect), the magnetostrictive materials  50  have high efficiency.   Power generation by resonant vibration is obtained.   A wide temperature use range (−100° C. to 100° C.) is provided.       

     When the housing is vibrating, as described above, the magnetostrictive materials  50  of the power-generating unit  14  are deformed by the vibration to generate power. However, even when the housing is not vibrating, the magnetostrictive materials  50  are deformed by force stored in the spring  12  to generate power. For example, as shown in  FIG. 2 , when the magnetostrictive materials  50  are formed in a plate shape (or a rod shape), force stored in the spring  12  may be transmitted in a direction (an arrow direction of  FIG. 2 ), in which the magnetostrictive materials  50  are deflected, to cause the power-generating unit  14  to generate power. An opposite side (an upper side of  FIG. 2 ) of a portion (an arrow portion of  FIG. 2 ) to which force stored in the spring  12  is transmitted is fixed, and if force stored in the spring  12  is transmitted, the magnetostrictive materials  50  are deflected. 
     Force stored in the spring  12  may be transmitted in a direction in which the magnetostrictive materials  50  expand and contract in a longitudinal direction to cause the power-generating unit  14  to generate power. 
     The power-generating unit  14  supplies the generated power (power by the vibration of the housing or power by force stored in the spring  12 ) to the secondary battery  20  through the capacitor  16 . The capacitor  16  is used so as to stabilize power supplied to the secondary battery  20 . 
     With the electronic device  1  according to the first embodiment of the invention, when the housing is vibrating, the power-generating unit  14  generates power using the vibration of the housing, and the spring  12  stores force. When the housing is not vibrating, the power-generating unit  14  generates power using force stored in the spring  12 . Therefore, continuous power generation becomes possible even when the housing is not vibrating. 
     When power generation is carried out using the magnetostrictive materials  50 , as described above, a large amount of power can be obtained compared to a piezoelectric element, and it is more robust and more suitable for reduction in size. As described above, with the characteristics of the magnetostrictive materials  50  or since vibration energy of the housing is changed to electric energy in the magnetostrictive materials  50 , and is also retained in the spring  12  as elastic energy, high-efficiency power generation becomes possible. A stable amount of power generation can also be obtained regardless of the magnitude of vibration. 
     In the configuration of the power-generating unit  14  shown in  FIG. 2 , if the vibration of the magnetostrictive materials  50  is resonant vibration, the efficiency of power generation is improved. Hereinafter, a configuration in which a resonance frequency can be changed will be described. 
       FIGS. 3A and 3B  are schematic views of a power-generating unit  114 .  FIG. 3A  is a sectional view in which the magnetostrictive materials  50  in the coil  52  are shown, and  FIG. 3B  is a sectional view showing a section along the broken line S of  FIG. 3A .  FIGS. 3A and 3B  respectively show the coil  52  wound around the two magnetostrictive materials  50  together and the coil  52  wound around each magnetostrictive material  50 . 
     The power generator  10  may include the power-generating unit  114  shown in  FIG. 3A  instead of the power-generating unit  14  shown in  FIG. 2 . The power-generating unit  114  has magnetostrictive materials  50 , a coil  52 , and a movable portion (weight)  54 . The movable portion  54  is movable in the longitudinal direction (an arrow A direction of  FIG. 3A ) of the magnetostrictive materials  50 . The distance between the fixed portion  55  and the movable portion  54  changes with the movement of the movable portion  54 . 
     In the configuration of the power-generating unit  114  shown in  FIG. 3A , since the position of the movable portion  54  changes, and the distance between the fixed portion  55  and the movable portion  54  changes, the resonance frequency can be changed. That is, if the distance between the fixed portion  55  and the movable portion  54  is shortened, the resonance frequency increases, and if the distance between the fixed portion  55  and the movable portion  54  is extended, the resonance frequency decreases. 
     As a method of changing (method of adjusting) the position of the movable portion  54  (the distance between the fixed portion  55  and the movable portion  54 ), a few methods are considered. For example, an actuator (not shown) is arranged outside the movable portion  54 , and the actuator applies force to the movable portion  54  such that the movable portion  54  moves in the longitudinal direction of the magnetostrictive materials  50  to change the position of the movable portion  54 . An actuator (not shown) may be arranged inside the movable portion  54 , and the movable portion  54  may be self-propelled by the driving of the actuator to change the position of the movable portion  54 . 
     The optimum resonance frequency may be determined from the position of the movable portion  54  at which the amount of generated power is maximal in a state where the housing is vibrating. When the housing is not vibrating, the movable portion  54  is moved using force stored in the spring  12  in a direction (an arrow B direction of  FIG. 3A ) in which the magnetostrictive materials  50  are deflected, and the magnetostrictive materials  50  are deformed to perform power generation. 
     Although the first embodiment of the invention has been described in detail referring to the drawings, a specific configuration is not limited to the embodiment, and changes may be appropriately made without departing from the scope of the invention 
     Second Embodiment 
     Hereinafter, a second embodiment of the invention will be described referring to the drawings. 
       FIG. 4  is a schematic functional configuration diagram of an electronic device  2  according to a second embodiment of the invention. As shown in  FIG. 4 , the electronic device  2  has a processing unit  230  which performs predetermined processing, a power supply unit  220  which supplies power to the processing unit  230 , and a power-generating unit  210  which generates at least a part of power supplied from the power supply unit  220  to the processing unit  230 . As the electronic device  2 , a portable information terminal or the like which is formed of a portable size is provided. 
     The processing unit  230  includes an input unit  232 , a control unit  234 , a storage unit  236 , and an output unit  238 . The input unit  232  inputs information from the outside. While the input unit  232  differs depending on the type of the electronic device  2 , for example, a receiving unit which receives information transmitted from the outside, an operation-receiving unit which receives an input operation by an operator, a detection unit (for example, a magnetic sensor) which detects an external environment, or the like corresponds to the input unit  232 . 
     The control unit  234  performs various kinds of processing based on information input by the input unit  232 , information stored in the storage unit  236 , or the like. The storage unit  236  stores information input by the input unit  232 , information (for example, a control program) which is used for processing by the control unit  234 , information (for example, output information) generated by the control unit  234 , or the like. 
     The output unit  238  outputs information to the outside. While the output unit  238  differs depending on the type of the electronic device  2 , for example, a transmitting unit which transmits information to the outside, a presentation unit (for example, a display, a lamp, or a speaker) which presents information to the operator, a driving unit which drives (for example, a vibration function) the housing (hereinafter, referred to as a “housing”) of the electronic device  2 , or the like corresponds to the output unit  238 . 
       FIG. 5  is a perspective view showing the configuration of the power-generating unit  210 . 
     As shown in  FIG. 5 , the power-generating unit  210  has a frame portion  211 , a vibrating portion  212 , a vibration transmission portion  213 , and a coil portion  214 . The power-generating unit  210  has a configuration in which the vibrating portion  212  and the vibration transmission portion  213  are integrally supported by the frame portion  211 . The frame portion  211  is fixed to the housing or the like of the electronic device  2 . 
     The vibrating portion  212  has a linear member  212   e  including a magnetostrictive material. The vibrating portion  212  has a configuration in which the linear member  212   c  is wound in a spiral shape (spring shape) in a predetermined direction. For this reason, the vibrating portion  212  is configured to expand and contract in the predetermined direction. Specifically, the vibrating portion  212  is deformed by force (bending force, pulling force, stretching force, or the like) from the outside, and expands and contracts in a predetermined direction. 
     As the magnetostrictive materials, for example, a Fe—Ga-based material (iron-gallium alloy) is used. 
     Since the vibrating portion  212  includes the magnetostrictive material, the vibrating portion  212  has a function of causing change in surrounding magnetic flux density when deformed (inverse magnetostriction effect). 
     A first end portion (an upper end portion in the drawing)  212   a  of the vibrating portion  212  in one direction is fixed to a fixed portion  211   a  of the frame portion  211 . The fixed portion  211   a  is provided to protrude from the frame portion  211 . An opposite second end portion  212   b  of the vibrating portion  212  in one direction is connected to a movable portion  213   b  of the vibration transmission portion  213 . 
     The vibration transmission portion  213  has a weight body  213   a  and a movable portion  213   b . The vibration transmission portion  213  transmits vibration to the vibrating portion  212 . The weight body  213   a  is connected to the second end portion  212   b  of the vibrating portion  212  through the movable portion  213   b . The movable portion  213   b  is configured such that one end portion  213   c  is supported by the frame portion  211 , and the other end portion  213   d  is rotatable around the end portion  213   c  supported by the frame portion  211 . 
     The weight body  213   a  is arranged at the other end of the movable portion  213   b . The second end portion  212   b  of the vibrating portion  212  is connected between the end portion  213   c  and the end portion  213   d  of the movable portion  213   b.    
     When the electronic device  2  vibrates, the weight body  213   a  makes it easy to transmit the vibration of the electronic device  2  to the vibrating portion  212  on a leverage principle. Examples of the vibration of the electronic device  2  include vibration when the user intentionally shakes the electronic device  2 , vibration when the user carries the electronic device  2 , driving (for example, a vibration function) by processing of the processing unit  230 , and the like. 
     The coil portion  214  generates an induced current according to change in magnetic flux density caused by the vibration of the vibrating portion  212 .  FIG. 6  is a diagram showing a part of the vibrating portion  212  on a magnified scale. As shown in  FIG. 6 , the coil portion  214  has a configuration in which an electric wire  214   a  is wound around the linear member of the vibrating portion  212 . As the configuration of the coil portion  214 , in addition to the configuration in which the electric wire  214   a  is directly wound around the linear member of the vibrating portion  212 , for example, a configuration in which the linear member of the vibrating portion  212  is formed so as to be covered with a tube member, and an electric wire is formed on the tube member may be made. The electric wire  214   a  of the coil portion  214  is connected to the power supply unit  220 . 
     Next, an operation when power generation is performed using the electronic device  2  configured as described above will be described. While the user holds the electronic device  2 , the electronic device  2  receives force, impact, or the like from the user. At this time, the weight body  213   a  vibrates by force, impact, or the like. If the weight body  213   a  vibrates, the vibration is transmitted to the movable portion  213   b . The movable portion  213   b  vibrates in a rotation direction around the end portion  213   c  supported by the frame portion  211 . The vibration of the movable portion  213   b  is transmitted to the vibrating portion  212  through the second end portion  212   b . In this way, the movable portion  213   b  vibrates with the weight body  213   a  on the leverage principle, whereby the vibration which is transmitted to the vibrating portion  212  increases compared to a case where the weight body  213   a  is not provided. 
     If the vibration from the movable portion  213   b  is transmitted, the vibrating portion  212  expands and contracts in a predetermined direction. Since the vibrating portion  212  includes the magnetostrictive material, magnetic flux density around the vibrating portion  212  changes due to deformation at the time of the expansion and contraction of the vibrating portion  212 . If change in magnetic flux density occurs, in the coil portion  214 , an induced current based on change in magnetic flux density is generated. In this way, the power generation operation in the power-generating unit  210  is performed. 
     The induced current generated in the coil portion  214  is supplied to the power supply unit  220  through the electric wire  214   a . A capacitor (not shown) may be provided between the coil portion  214  and the power supply unit  220 . The capacitor is used so as to stabilize power supplied to the power supply unit  220 . In this way, power is stored in the power supply unit  220  by the induced current supplied from the power-generating unit  210 . 
     As described above, according to this embodiment, the vibrating portion  212  which is formed to have a spiral shape in a predetermined direction and includes a magnetostrictive material, the vibration transmission portion  213  which transmits vibration to the vibrating portion  212 , and the coil portion  214  which generates an induced current according to change in magnetic flux density caused by the vibration of the vibrating portion  212  are provided, whereby reduction in size becomes possible compared to a configuration in which power generation is carried out using a piezoelectric material, for example. 
     That is, for example, a piezoelectric material, such as ceramics, is a brittle material and is thus unsuitable for processing. In contrast, since the magnetostrictive materials are hard to break and are ductile, mechanical processing is possible. Accordingly, since extreme reduction in size (about several millimeters) is possible, it is useful for mounting in a compact electronic device (for example, a portable music player, a mobile communication device, or a human body-implantable medical device). 
     In this embodiment, since a magnetostrictive material is included in the vibrating portion  212 , for example, power to be obtained increases compared to a case where a piezoelectric element (piezoelectric material) is deformed to generate a current. This is because the piezoelectric material has high impedance compared to the magnetostrictive material. When a magnetostrictive material is used, power generation by resonant vibration becomes possible. When a magnetostrictive material is used, power generation is possible even in a wide temperature use range (for example, −100° C. to 100° C.). 
     The technical scope of the invention is not limited to the foregoing embodiment, and changes may be appropriately made without departing from the scope of the invention. 
     For example, although in the foregoing embodiment, a configuration in which the electric wire  214   a  of the coil portion  214  is wound around the linear member  212   c  of the vibrating portion  212  has been described as an example, the invention is not limited thereto. 
     For example, as shown in  FIG. 7 , the coil portion  214  may be arranged so as to surround the periphery of the vibrating portion  212 . In this case, a plurality of coil portions  214  are provided around the vibrating portion  212 , and in each coil portion  214 , an electric wire  214   a  is wound around a core portion  214   b . In this case, as in the foregoing embodiment, reduction in size is possible. In this case, if the coil portion  214  is used as a weight body, and vibration is transmitted to the vibrating portion  212 , further reduction in size becomes possible. 
     For example, although in the foregoing embodiment, a configuration in which the movable portion  213   b  is attached to the second end portion  212   b  of the vibrating portion  212 , and the weight body  213   a  is connected to the second end portion  212   b  through the movable portion  213   b  has been described as an example, the invention is not limited thereto. For example, as shown in  FIG. 8 , the weight body  213   a  may be directly attached to the second end portion  212   b  of the vibrating portion  212 . In this case, as in the foregoing embodiment, reduction in size becomes possible. 
     Although in the foregoing embodiment, a configuration in which an induced current generated by the power-generating unit  210  according to the vibration of the electronic device  2  is supplied to the power supply unit  220  each time has been described as an example, the invention is not limited thereto. For example, a vibration storage portion which stores force (elastic energy) for causing the vibrating portion  212  to vibrate may be provided. 
     In this configuration, the movable portion  213   b  can be moved by force stored in the vibration storage portion, and the vibrating portion  212  can vibrate through the movable portion  213   b . For this reason, continuous power generation becomes possible even when the electronic device  2  is not vibrating. As the vibration storage portion, for example, a spring mechanism or the like may be used. 
     Although in the foregoing embodiment, a configuration in which the weight body  213   a  and the movable portion  213   b  are provided as the vibration transmission portion  213  has been described as an example, the invention is not limited thereto. For example, a resonance structure or the like may be attached to the power-generating unit  210 . Therefore, it is possible to efficiently vibrate the vibrating portion  212 . 
     For example, although in the foregoing embodiments, a form in which the weight body  213   a  or the weight body  214  is provided outside the vibrating portion  212  has been described, the invention is not limited thereto. For example, the shape of the coil may be used, and the weight body  213   a  or the weight body  214  may be formed inside the vibrating portion  212 . Therefore, it becomes possible to achieve further reduction in size.