TECHNICAL FIELD The present invention relates to a vibration generator and, more particularly, to a vibration generator capable of converting vibration energy into electrical energy to be used as an emergency or auxiliary charging means of a portable (mobile) information device or the like .

BACKGROUND ART

A lithium ion battery used for a mobile phone, sort of typical portable information device, is driven with a voltage of about 4.2V±0.05V. As the technologies are advanced, mobile phones tend to consume less power, and in order to increase a computing rate and reduce power consumption of mobile phone, the size of voltage is being reduced.

The general portable information devices used according to the known art are mostly charging type terminals that charge power by using a charger regardless of its type, but the charger can be found merely at convenience stores , airports or terminals , etc . where people are crowded. Thus , when a user of the charging type terminal is in a fishing place, mountain climbing, in a

disaster, is isolated due to a natural disaster, or in a critical condition, if its battery is completely discharged (used up) , the user cannot transmit a rescue request signal .

DISCLOSURE OF THE INVENTION

TECHNICAL PROBLEM

Therefore, an obj ect of the present invention is to provide a vibration generator capable of increasing a battery usage time by converting energy according to natural vibration such as vibration made by a hand movement or walking, etc . into electrical energy and charging a battery with the electrical energy, and providing power to an information device in a discharged state even with weak vibration in case of emergency.

TECHNICAL SOLUTION

To achieve the above obj ect , there is provided a vibration generator including : a hollow case with a predetermined length with both sides thereof closed; a winding part wound with a predetermined thickness on an inner circumferential surface of the case ; springs installed with a predetermined length at the both end sides in the closed case; a moving permanent magnet installed between the springs and freely moving with a predetermined gap inside the case ; and a movement guide shaft penetrating

the center of the moving permanent magnet , the springs with the predetermined length being attached on both end portions of the movement guide shaft . There is also provided a vibration generator in which fixed permanent magnets , instead of a spring, are attached at both ends to face a moving permanent magnet in the same polar direction in the closed case, to thereby obtain energy even with weak vibration . Finally, there is also provided a vibration generator without a spring in which a case is made of a non-magnetized material to convert small vibration energy without a shaft for guiding movement of a moving permanent magnet .

ADVANTAGEOUS EFFECTS The vibration generator in accordance with the present invention has such effects that it can convert energy according to small vibration into electrical energy to charge a battery to thereby increase a battery usage time, and when a user stays outdoors for an outdoor activity for a long time, when the user takes a long business trip, or if the user is put in a disastrous situation in a fishing place or mountain climbing, or in case of any other similar emergency, the battery can be charged by using the power generation function and used .

DESCRIPTION OF DRAWINGS

FIG . l is a sectional view showing the structure that springs are provided in a vibration generator in accordance with a preferred embodiment of the present invention . FIG . 2 is a sectional view showing the structure that permanent magnets are provided in the vibration generator in accordance with the preferred embodiment of the present invention .

FIG . 3 is a view showing magnetic flux distribution of a cylindrical permanent magnet in accordance with the preferred embodiment of the present invention .

FIG . 4 is graphs showing a magnetic flux waveform and an electromotive force waveform according to a reciprocal linear movement of the permanent magnet in accordance with the preferred embodiment of the present invention .

FIG . 5 is a sectional view of the vibration generator in which several coils are connected in series in accordance with the preferred embodiment of the present invention . FIG . 6 is graphs showing electromotive force of the vibration generator in accordance with the preferred embodiment of the present invention .

FIG . 7 is a sectional view showing the interior of a cylinder in which several bunches of coils are provided on its inner surfaces and adj acent coil bunches have the

opposite current directions .

FIG . 8 is a view showing the structure that coils are wound on the vibration generator in FIG . 7.

FIG . 9 is a graph showing overall electromotive force obtained by connecting coils in series to the vibration generator in FIG . 7.

FIG . 10 is a conceptual view of a circuit for charging a portable information device in accordance with the preferred embodiment of the present invention . FIG . 11 is a sectional view showing a vibration generator without a movement-guiding shaft therein in accordance with the preferred embodiment of the present invention .

BEST MODE

The preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings .

To begin with, the present invention provides a vibration generator for converting vibration energy into electrical energy . A technology or a product for converting energy according to vibration into electrical energy has not been presented yet, and most generators in the known arts have a form of a rotary machine but the present invention provides a linear generator which makes a linear

reciprocal movement . In addition, the vibration generator of the present invention can be fabricated as an integrated or separated form as an emergency or auxiliary charging means of a portable information device . The vibration generator of the present invention can be fabricated in several types such as AA or AAA size of a cylindrical battery, or can have various shapes such as rectangular parallelepiped shape .

FIG . l is a sectional view showing the structure that springs are provided in a vibration generator in accordance with a preferred embodiment of the present invention . In FIG . 1 (a ) , a vibration generator includes a hollow case 1 with a predetermined length with both sides closed, a winding part 2 formed to be wound with a predetermined thickness on an inner circumferential surface of the case 1 , springs 5 installed with a predetermined length at both end sides in the closed case 1 , a moving permanent magnet 3 installed between the springs 5 and freely moving with a predetermined gap 4 inside the case 1 , and a movement guide shaft 6 penetrating the center of the moving permanent magnet 3 , the springs 5 being attached with the predetermined length at both end portions of the moving permanent magnet 3.

In more detail , the case 1 forms a body of an overall vibration generator, serves to protect internal components

and is made of a hard material which can be easily magnetized . The case 1 has various shapes such as a cylindrical shape or a square shape depending on the shape of the moving permanent magnet 3. The winding part 2 formed to be wound with the predetermined thickness on the inner circumferential surface of the case 1 generates electromotive force according to Faraday ' s Law owing to the reciprocal movement of the moving permanent magnet 3 vibrated according to an external force . The size of the electromotive force or a generated voltage is proportional to a frequency of the reciprocal movement , the number of turnings of the winding, a magnetic flux density of the moving permanent magnet 3 , and a distance of the reciprocal movement of the moving permanent magnet 3. When a terminal of the winding part 2 is connected with a battery or an electrical load, kinetic energy according to the reciprocal movement or vibration of the moving permanent magnet 3 can be converted into electrical energy to transfer power . Thus , as the winding, preferably, a conductive line such as copper is used and the winding must be insulated .

The moving permanent magnet 3 installed between the springs 5 and freely moving with a predetermined gap 4 inside the case 1 has a hole at its central portion formed suitably according to its movement direction so that it can

be moved along the movement guide shaft 6 which is penetratingly inserted in the hole . In addition, in order to prevent the moving permanent magnet 3 from contacting with the winding part 2 to undesirably cause a load inside the case 1 , the gap 4 is preferably formed between the moving permanent magnet 3 and the winding part 2. Preferably, the moving guide shaft 6 is made of a non- magnetized (non-magnetic) material .

The springs 5 installed at both end sides in the closed case 1 store kinetic energy of the moving permanent magnet 3 generated when the moving permanent magnet 3 changes its movement direction in its reciprocal movement as spring energy to make the changing of the direction smooth, and reduce noise generated according to possible collision of the moving permanent magnet 3 with the inner side surface of the case 1 as well as protecting the moving permanent magnet 3 against the collision . Thus , preferably, the both ends and the springs 5 are made of a non- magnetized material . A spring modulus is preferably set to generate maximum power at an external operation frequency band applied to the case 1 under the condition that the movement distance of moving permanent magnet is limited according to the length of the case 1 together with a mass value of the moving permanent magnet 3. The moving permanent magnet 3 installed between the

springs 5 and freely moving with the predetermined gap inside the case 1 serves to supply mass accumulating kinetic energy and magnetic flux changing over time to the winding part 2. Thus , in order to maximize the kinetic energy, specific gravity must be high and in order to maximize the magnetic flux supplied to the winding part 2 , the moving permanent magnet 3 needs to be made of a material with high density . The moving permanent magnet 3 can have various shapes such as a cylindrical shape or a square pillar shape, etc . together with the case 1 , and it is magnetized in the height wise direction of the cylinder or square pillar . In order to increase mass of the moving permanent magnet 3 , the moving permanent magnet 3 preferably comprises a material with high specific gravity . In order for the moving permanent magnet 3 to be moved reciprocally, a moving permanent magnet reciprocal movement space 9 is provided in the case 1 The gap 4 is formed in the moving permanent magnet reciprocal movement space 9 when the moving permanent magnet 3 is reciprocally moved. FIG . l (b) is a sectional view taken along line ' A-A ' of FIG . 1 (a) , and FIG . 1 (c) is a sectional view taken along line ' B-B ' of FIG . l ( a ) . In particular, an isolation space 7 is formed with a small interval in order to reduce a frictional force generated when the moving permanent magnet 3 is reciprocally moved along the moving guide shaft 6.

FIG . 2 is a sectional view showing the structure that permanent magnets are provided in the vibration generator in accordance with the preferred embodiment of the present invention . In the vibration generator, the fixed permanent magnets are attached at both ends in the same magnetization direction as that of the moving permanent magnet 3 inside the case 1 , playing the role of the springs 5. That is , since the moving permanent magnet 3 and the fixed permanent magnets 8 are disposed to face each other with the same polarity, a pushing force works there between, making the moving permanent magnet 3 quite unstable to be moved easily even with small vibration . With such a structure, when the case 1 is made of a non-magnetized material , it can easily generate energy with small vibration even without the movement guide shaft 6.

FIG . 3 is a view showing magnetic flux distribution of a cylindrical permanent magnet in accordance with the preferred embodiment of the present invention . In case that the case 1 is made of a material which can be easily magnetized, magnetic flux interlinks a coil and then returns by using the case 1 as a magnetization passage, and as the moving permanent magnet 3 is reciprocally and linearly moved inside the case 1 , the magnetic flux interlinked with the coil is changed according to Faraday ' s Law to generate induced electromotive force . Compared with

a non-magnetized (non-magnetic) case 1 , the magnetic flux path is quite short, so the size of the magnetic flux is much improved and the electromotive force induced to the coil is increased . The graph (a) in FIG . 4 shows the magnetic flux distribution viewed from the position of the coil based on the direction in which the moving permanent magnet 3 is moved as shown in FIG . 3. The size of the magnetic flux is determined by magnetic flux density and the sectional area of the moving permanent magnet 3 , and a voltage induced to one coil by the moving permanent magnet 3 during its movement is obtained by differentiating the magnetic flux distribution over time according to Faraday ' s Law as shown by the graph (b) in FIG . 4. The graph (b) in FIG . 4 shows an actual waveform reflecting a theoretical square waveform and a leakage flux .

The size of the induced voltage is determined by the magnetic flux density, a radius of the cross section of the permanent magnet and its vibration frequency, and a period of a waveform is determined by the length and the diameter of the moving permanent magnet 3 and the gap 4. With the leakage flux taken into account, the induced electromotive force has the waveform indicated by a dotted line .

FIG . 5 is a sectional view of the vibration generator in which several coils are connected in series in accordance with the preferred embodiment of the present

invention . The number of windings for connecting several coils in series to increase the size of the electromotive force is determined by the diameter of wire, the length and diameter of the moving permanent magnet and the length of the gap 4. The winding part 2 can be fabricated with a one- layer structure, a two-layer structure or a three-layer structure, and in this case, the layer is called a coil bunch .

FIG . β is graphs showing electromotive force of the vibration generator in accordance with the preferred embodiment of the present invention . FIG . 6 ( a ) shows a proximate sinusoidal wave shape of the electromotive force induced to each coil , and FIG . 6 (b) shows combined electromotive force obtained by connecting the coils in series . The size of the combined electromotive force is determined by the magnetic flux density of the moving permanent magnet , the radius of the cross section of the moving permanent magnet, the vibration frequency, and the number of serial windings . The period of the combined electromotive force is equivalent to the sum of the period of electromotive force according to one coil of one winding and the interval of the coil wound in one direction .

FIG . 7 is a sectional view showing the interior of a cylinder in which several bunches of coils are formed on its inner surfaces and adj acent coil bunches have the

opposite current directions . In the vibration generator, a current direction is the same in one coil bunch but current directions of adj acent coil bunches are the opposite . In case where the winding part 2 is formed as a single layer winding, as shown in FIG . 8 , wire is successively wound on the cylinder by changing only the direction without being cut off . In case of the three-layer winding, as shown in FIG . 8 , the coil is wound around the cylinder, and when one coil bunch is completed, the coil is successively wound in the same direction, going around the opposite side in the horizontal direction, and when the coil reaches its original position, it is wound again in the same direction, going around the opposite side in the horizontal direction, to thereby complete one directional winding of one coil bunch . When this operation is performed repeatedly by changing only the coil winding direction to the opposite, a coil bunch of a different current direction can be completed . By performing this method repeatedly, the coil can be easily wound successively without a cutoff or linking .

FIG . 9 is a graph showing overall electromotive force obtained by connecting the coils in series to the vibration generator in FIG . 7. As shown, because respective electromotive forces of neighboring coil bunches overlap with each other, the size of electromotive force is doubled

and an effective voltage of one period of reciprocal movement of the moving permanent magnet by the several bunches of coils can be considerably increased . In addition, when the coil bunches are connected in series , the overall combined electromotive force can be generated. Accordingly, the terminal electromotive force voltage of the vibration generator 40 appears as an AC voltage, and as shown in FIG . 10 , the AC voltage can be transferred to be charged in the battery 10 , which uses a DC voltage, through a rectifying circuit and charging circuit 30 or transferred to the load 20.

FIG . 11 is a sectional view showing a vibration generator without a movement-guiding shaft in accordance with the preferred embodiment of the present invention . As shown in FIG . 11 , the vibration generator includes a hollow case 1 made of a non-magnetized material with a predetermined length with both sides closed, a winding part 2 formed to be wound with a predetermined thickness on an inner circumferential surface of the case 1 , a moving permanent magnet 3 installed between fixed permanent magnets 8 and freely moving with a predetermined gap 4 inside the case, and the fixed permanent magnets 8 formed at both end sides of the closed case and facing the moving permanent magnet 3 with the same polarity inside the case 1 , thereby converting small vibration energy.

INDUSTRIAL APPLICABILITY

As described above, the vibration generator in accordance with the present invention have such effects that it can convert energy according to small vibration into electrical energy to charge a battery to thereby increase a battery usage time, and when a user stays outdoors for an outdoor activity for a long time , when the user takes a long business trip, or if the user is put in a disastrous situation in a fishing place or mountain climbing, or in case of any other similar emergency, the battery can be charged by using the power generation function and used. Therefore, the vibration generator in accordance with the present invention is inventive in the field of the battery industry and favorably adopted for mobile phones .