BACKGROUND ART Generally, an in-line skate where a plurality of rollers rotatably mounted on support stands are arranged in a straight line is assembled with a footgear and by the repeating movement in a zigzag manner using both feet of a user, it advances in a desired direction.

Since the in-line skates have more sophisticated external appearance and rapider speed than conventional roller skates, it is very popular at a fast speed among young ages. At present, it is often found that an in-line skate lover's society having numerous members is increased in number over PC communications or Internet sites.

As well known, since the in-line skates have a relatively rapid speed performance, if a user who wears the in-line skates collides against a moving object such as a pedestrian or an automobile, there occurs a problem that he may be injured. To improve a visually esthetic feeling of the in-line skate as well as to solve the above problem, many studies for the roller as a driving body, namely, wheels of the in-line skate are unceasingly made.

A conventional in-line skate structure is disclosed, as shown in Figs. 1 and 2, in Korean Patent Laid-open Application No. 99-78816. As shown, a plurality of light emitting wheels 20 are mounted on support stands 12 on the lower portion of an in-line skate footgear 10. In this case, since each of the light emitting wheels 20 includes a permanent magnet 128 that takes a ring shape of a predetermined thickness, the permanent magnet 128 has a relatively poor strength and may be slipped during the rotation of the wheel 20, thereby failing to emit the light from the wheel.

While the permanent magnet 128 is exposed to the outside, also, since a bushing 124 is disposed in the inside, there occurs a problem that upon application of the external impacts, the permanent magnet 128 may be slipped or damaged. Additionally, an armature core 143 takes a spaced square shape in its section, such that there occurs a problem that wheel rotation torque, that is, the degree of load applied during the rotation of the wheel 20, is increased (an explanation of which will be later discussed).

Furthermore, a hub assembling body 22 has a closed structure, such that there occurs a problem that the whole weight of the wheel 20 is increased and the emission of the heat according to the rotation is not achieved in an easy manner. Also, a circuit part is made of a copper plate, such that there occur some problems that the assembling capability is deteriorated, the external appearance is not beautiful, and the resistance against the external shocks is weak.

DISCLOSURE OF INVENTION It is, therefore, an object of the present invention to provide an improved generator and a light emitting wheel having the generator capable of

decreasing rotation load according to the rotation of the light emitting wheel, preventing the generation of the slipping of a magnet and protecting the magnet from external impacts.

It is another object of the present invention to provide an improved generator and a light emitting wheel having the generator capable of insert- molding a printed circuit board in the interior thereof, thereby improving an external appearance, shock resistance and an assembling capability.

It is yet another object of the present invention to provide an improved generator and a light emitting wheel having the generator capable of providing a circuit structure where the light emitted from an light emitting element is controlled according to the rotation speed of the wheel.

According to an aspect of the present invention, there is provided an improved generator for generating electricity according to the rotation of a wheel, which includes: a spacer disposed on a check nut passing through a hub installed in the interior of a tire, the spacer passing the check nut therethrough ; an inside protecting bushing into which the spacer is inserted; a cam-type magnet assembly having a cam-type magnet into which the inside protecting bushing is inserted and an outside protecting bushing into which the inside protecting bushing is inserted ; iron cores facing to each other and interposing an iron core center portion therbetween ; an armature coil assembly having a coil bobbin coupled to each of the upper and lower portions of the iron cores and magnetized by means of the cam-type magnet of the cam-type magnet assembly to thereby conduct an electromagnetic induction action; and a plurality of bearings for selectively rotating the armature coil assembly in accordance with the rotation of

the wheel.

According to another aspect of the present invention, there is provided a light emitting wheel for emitting light according to the rotation thereof, which includes: a generator having a spacer disposed on a check nut passing through a hub installed in the interior of a tire, the spacer installed on the external surface of the check nut, an inside protecting bushing into which the spacer is inserted, a cam-type magnet assembly having a cam-type magnet inserted on the front end of the inside protecting bushing and an outside protecting bushing inserted into the external surface of the inside protecting bushing is inserted, iron cores having an iron core center portion therebetween, an armature coil assembly having a coil bobbin coupled to each of the upper and lower portions of the iron cores and magnetized by means of the cam-type magnet of the cam-type magnet assembly to thereby conduct an electromagnetic induction action, and a plurality of bearings for selectively rotating the armature coil assembly in accordance with the rotation of the wheel; a printed circuit board having a plurality of light emitting elements and a light control circuit according to rotation speed change and connected to a lead wire of the armature coil assembly ; and a tire of a transparent material fixing the hub in the interior thereof in a molding manner and fixedly inserting the generator in the interior thereof In the preferred embodiment of the present invention, the iron core center portion is structured in a triangular overlapped manner.

In the preferred embodiment of the present invention, the inside protecting bushing is provided with a plurality of shock-absorbing locking protrusions along the circumferential surface of the front end thereof and

between the locking protrusions is provided a guide into which the cam-type magnet is inserted.

In the preferred embodiment of the present invention, the armature coil assembly is insert-molded within the hub.

In the preferred embodiment of the present invention, the coil bobbin is composed of a body on which an armature coil is wound in two-stage manner and a support bar having the lead wire of the armature coil extruded on the front end of the center thereof and formed on the center of the body.

In the preferred embodiment of the present invention, the hub is provided with a plurality of second openings for emitting an internal heat according to the rotation of the wheel, in a circumferential surface on the inside frame thereof.

In the preferred embodiment of the present invention, each of the light emitting elements is a light emitting diode chip.

In the preferred embodiment of the present invention, the plurality of light emitting elements are disposed on the both sides of the printed circuit board, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematically perspective view illustrating an in-line skate on which conventional light emitting wheels are mounted ; Fig. 2 is an exploded perspective view illustrating the conventional light emitting wheel of Fig. 1; Fig. 3 is a plan view illustrating a light emitting wheel according to the present invention ;

Fig. 4 is an exploded perspective view of Fig. 3; Fig. 5 is a side sectional view illustrating the state where the assembling of the light emitting wheel according to the present invention is completed; Fig. 6a is a perspective view illustrating the cam-type magnet in the light emitting wheel according to the present invention ; Fig. 6b is a top view of the light emitting wheel in Fig. 6a; Figs. 6c to 6e are plan, top and side views of the light emitting wheel according to the present invention ; Figs. 7a and 7b are top and side views illustrating the inside protecting bushing in the light emitting wheel according to the present invention; Fig. 8 is an assembly view illustrating the state where the iron core, the coil bobbin and the printed circuit board are assembled in the light emitting wheel according to the present invention ; Fig. 9 is a top view illustrating the state where the iron core, the coil bobbin and the printed circuit board of Fig. 8 are assembled with the wheel hub ; Fig. 10 is a perspective view illustrating the coil bobbin in the light emitting wheel according to the present invention ; Fig. 11 is a graph illustrating the compared results of the iron core shape between the prior art and the present invention and the output waveform therebetween ; Fig. 12 is a graph illustrating the compared results of current values according to wheel speed between the prior art and the present invention ; Fig. 13 is a block diagram illustrating a speed change circuit of the light emitting wheel according to the present invention ; and

Fig. 14 is a circuit diagram illustrating the construction of the speed change circuit according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Now, an explanation of the configuration and operation of an improved generator and a light emitting wheel according to the present invention will be hereinafter discussed with reference to the accompanying drawings.

Figs. 3 to 10 and Figs. 13 and 14 show an improved generator and a light emitting wheel according to the present invention. As shown in Figs. 3 to 5, a wheel 50 is provided with a tire 52 of a transparent thermosetting polyurethane material and a hub 54 fixedly molded in the interior of the tire 52. So as to reduce the whole weight of the wheel 50, to emit the internal heat according to the rotation of the wheel 50, and to enhance the rigidity of the hub 54, the inside frame of the hub 54 is provided with a plurality of second openings 56 on a circumference thereof on the inside of a plurality of openings formed in a general wheel shape on the circumference thereof, each of which is crossed to each of the plurality of openings.

A cam-type magnet assembly is inserted into the interior of the hub 54, and a spacer 62, which forms a'V'-shaped reentrant part 62-1 in a length direction on the one side of the external surface thereof, is inserted into an inside protecting bushing 64 forming a protrusion part 64-1 inserted into the reentrant part 62-1 on the one side of the inner peripheral surface thereof. The front end portion of the inside protecting bushing 64 is extruded in a predetermined thickness and then inserted into a cam-type magnet 66 as shown in Fig. 7. Also, an outside protecting bushing 68 of a ring shape is inserted into the outer

peripheral surface of the inside protecting bushing 64.

As shown in Figs. 6a to 6e, the inside protecting bushing 64 is provided with three locking protrusions 64-2 equally spaced on the circumferential surface of the front end portion thereof, which are inserted and coupled into the rounded portion of the inner peripheral surface of the cam-type magnet 66 to thereby function to absorb the external shocks. Between the protrusions 64-2 is provided a guide 64-3 which is inserted on the rectilinear portion of the inner peripheral surface of the cam-type magnet 66.

In Fig. 6e, a reference numeral 64-4 which is not described in the drawing denotes a supporting projection.

In the armature coil assembly, as shown in Figs. 8 to 10, there are provided an iron core 72 of a substantially diamond shape which is made of an iron material having an excellent magnetization alternation and an iron core center portion 72-2 of a substantially triangular shape which is formed in an overlapped manner circumferentially on the center of the iron core 72.

Additionally, a coil bobbin 76 is coupled by means of a rivet 78 on the upper and lower portions of the iron cores 72, respectively.

The coil bobbin 76 is provided with an armature coil 76-2 which is wound on a body 76-1 centering around a support bar 76-4 formed on the center portion thereof and a lead wire 76-3 of the armature coil 76-2 which is extruded on the front end portion of the center of the support bar 76-4.

The coil bobbin 76 is also provided with a'V'-sllaped protrusion 76-5 which is formed on the lower portions of the both sides of the support bar 76-4, respectively and upon coupling with the iron core 72, is inserted into a reentrant

part 72-1 formed on the upper and lower portions of the iron core 72, respectively.

The coil bobbin 76 has a two-stage structure where each armature coil 76-2 is wound centering around the support bar 76-4 to thereby emit the light to the inside and outside of the wheel 50 through light emitting elements 84 and 84- 1 of the wheel 50 as will be below discussed.

The armature coil assembly is insert-molded, as shown in Fig. 9, thereby being aligned on the center centering on the core of the hub 54.

On the other hand, a printed circuit board (PCB) 80 is mounted on the outside frame of the hub 54 and fixedly insert-molded with the hub 54 of the interior of the tire 52. The PCB 80 is in a quadrantal form and coupled by means of a pin 82 to the front end of the lead wire 76-3 of the armature coil 76-2. Also, the PCB 80 is provided with the light emitting elements 84 and 84-1, i. e., the light emitting diode chips equally spaced apart from each other, which are surface-mounted on the inner surfaces of the both sides thereof. The number of light emitting diode chips is appropriately set according to the design thereof and in the preferred embodiment of the present invention, is three.

The light emitting elements 84 and 84-1 serve to emit the light on the both sides of the wheel 50 via the armature coil 76-2 having the two-stage structure and upon connection of one of the three light emitting elements to the lead wire 76-3, the other light emitting elements can be all connected thereto.

By means of the coil bobbin 76 having the two-stage structure, the PCB 80 is set on the center of the hub 54 and thus, the light emitting elements 84 and 84-1 emit the light on the both sides of the wheel 50, such that if the one side of

the wheel 50 is wom out, the light can be emitted from the other side thereof.

The PCB 80 includes a well-known control circuit for separating the light emitted from the light emitting elements 84 and 84-1 during the rotation of the wheel 50 to thereby allow the light to be emitted at desired position and phase.

Also, the PCB 80 includes a control circuit for controlling the light of the light emitting elements 84 and 84-1 in accordance with the rotation speed change of the wheel 50.

If the change of a magnetic flux is generated in the iron core center portion 72-2 of the iron core 72 in accordance with the rotation of the armature coil assembly in the wheel 50, an induction electromotive force is generated on the armature coil 76-2 in proportion to the change of the magnetic flux.

Generally, the induction electromotive force is generated when the coil or the magnet rotates. In the preferred embodiment of the present invention, the cam-type magnet 66 is secured and if the armature coil 76-2 wound on the coil bobbin 76 rotates to change a magnetic field, the induction electromotive force is generated on the armature coil 76-2 under the Lorenz's principles.

As the induction electromotive force is generated, an alternating current flows to the armature coil 76-2 surrounding the iron coil 72. The flowing of the induced alternating current allows the light to be emitted through the light emitting elements 84 and 84-1. At this time, since the tire 52 is of the transparent material, the emitted light can be sensed on the rear portion of the wheel 50 as well as the inside and outside thereof, such that the user who wears the light emitting wheel 50 according to the present invention can be easily recognized to

moving objects such as pedestrians or automobiles at night, thereby preventing the accidents caused to the carelessness of the safety and improving the external appearance.

A bearing 90, which has a bushing 92 inserted into the internal wheel thereof, is inserted on the both sides of the center portion of the hub 54, respectively and a fixed nut 94 having a predetermined length of screw (which is not shown in the drawings) is passed through the bearing 90 and the spacer 62, thereby being coupled to the hub 54 by means of a fixed bolt 96.

The bearing 90 functions to support the spacer 62, the fixed nub 94 and the hub 54 and selectively rotates only the armature coil assembly during the rotation of the wheel 50, while preventing the rotation of the cam-type magnet assembly.

The spacer 62 is fixed on the internal wheel of the bearing 90 on the external surface of the fixed nut 94, such that the cam-type magnet assembly is fixed, and the fixed nut 94 is fixed on the support bar 76-4, such that only the armature coil assembly inclusive of the hub 54 rotates during the rotation of the wheel 50 and the cam-type magnet assembly is fixed.

On the head of the fixed bolt 96, there is provided a hexagonal head (which is not shown in the drawing) which is tightened by means of a hexagonal wrench, and the wheel 50 is fixedly inserted between the both support stands 12 of the in-line skate footgear 10 as shown in Fig. 1 and rotates through the fixed nut 94.

On the other hand, Fig. 11 is a graph illustrating the compared results of the iron core shape of the light emitting wheel between the prior art and the

present invention and the output waveform therefrom. In the prior art, the iron cores take a square shape and are spaced apart and the output waveform therefrom is shown by the graph 1. Contrarily, in the present invention the iron cores include the iron core center part 72-2 which is structured in a triangular overlapped manner and the output waveform therefrom is shown by the graph 2.

The substantial change of the magnetic line of force in the graphs 1 and 2 occurs between the points # and (2). In proportion to the slopes of the points (D and (2), therefore, the rotation torque of the wheel, i. e., the degree of load applied upon rotation of the wheel is increased. In the prior art, the section between A and B where the magnetic lines of force are not alternated is in a zero point of the magnetic line of force, and the section between B and C is in a maximum point of the magnetic line of force.

According to the present invention, the section between A and B does not almost exist, which means the changed curve point of the magnetic force (E) does not exist. To the contrary, in case of the iron core shape of the prior art, it can be appreciated that the rotation load is drastically applied upon rotation of the wheel, that is, upon the turning from the section between A and B to the section between B and C. In case of the iron core shape according to the present invention, however, since the section between A and B does not almost exist, the rotation inertia of the wheel is exerted at the maximum thereof and thus, the rotation torque applied upon rotation of the wheel is small.

Table 1 shows the compared results of the current value according to the wheel speed between the prior art and the present invention, and Fig. 12 is a graph for Table 1.

Table 1 Prior Art Present Invention Reference volt of 3 2 m/s 12 mA 12 mA 3nVs22mA21mA 4 m/s 32 mA 25 mA 5 m/s 46 mA 27 mA 6 m/s 54 mA 31 mA 7 m/s 64 mA 31 nLA 8 m/s 68 mA 32 mA

As shown in Table 1 and Fig. 12, in case of the present invention, the current necessary for emitting the light from the light emitting elements is in a saturated state in the range of the speed 2 m/s and 3 ris, but in case of the prior art, the current therefore is continuously increased. Therefore, in case of the present invention, even if the speed is further increased, the light emitting elements can be protected.

Fig. 13 is a block diagram illustrating a speed change circuit of the light emitting wheel according to the present invention, and Fig. 14 is a circuit diagram of the speed change circuit of Fig. 13. In this case, the voltage is increased in proportion to the speed of the wheel 50 and thus, the voltage level is detected, such that the light emitting diode chips operate with the division of colors.

As the coil bobbins 76 on the upper and lower portions of the iron core 72 are connected in serial to the PCB 80, a generating part supplies the alternating current induced to the coil bobbins 76 to the PCB 80.

A rectifying part supplies power to a control part by the rectification of full bridges and a direct current voltage to the control part for the comparison voltage thereof. The control part detects the voltage level and divides the rectified voltage level into one to three steps, thereby being switched by a light emitting diode driving part.

A control and speed detecting part compares the voltages of a comparator and if the voltage is over a predetennined level, turns on the light emitting diode chip. Also, the control and speed detecting part measures an indirect speed.

The LED driving part applies the alternating current that is not rectified to the LED chip in accordance with the switching signal of the control part.

On the other hand, the light emitting wheel according to the present invention is not limited to the in-line skates mainly described in the preferred embodiment of the present invention, and may be applied to a wheel-type rotary body which desires to have a light emitting effect such as, for example, roller skates each having two-line and four-wheel structure, a skate board, a kick board and so on.

As clearly described in the above, an improved generator and a light emitting wheel having the generator is capable of providing an iron core having the overlapped triangular portion to decrease the rotation torque of the wheel, thereby fully exerting the inherent function of the wheel.

Also, since a cam-type magnet is reinforced in thickness, it exerts a high resistance against the external impacts and prevents the slipping caused upon rotation of the wheel, thereby fully exerting the light emitting function

thereof.

Moreover, an improved generator and a light emitting wheel having the generator have the following advantages: since the circuit part is of a printed circuit board shape, an excellent assembling capability is exhibited ; since the circuit part is insert-molded within the hub, an external appearance is improved ; since the light of the light emitting element according to wheel speed is controlled, the wheel speed according to the light color can be recognized from the outside.