Abstract:
A light-emitting control circuit and a wrist training ball using the same are described. The wrist training ball includes a light-emitting device. The light-emitting device includes an electricity generating circuit and a light-emitting control circuit. The electricity generating circuit generates electric power by rotational kinetic energy of the wrist training ball and outputs the electric power to the light-emitting control circuit. The light-emitting control circuit includes first and second light-emitting elements. According to a voltage value of a voltage output by the electricity generating circuit, the first light-emitting element is turned-on to emit red-light, or the second light-emitting element is turned-on to emit blue-light, which is mixed with the red-light into purple-light due to visual persistence phenomenon, or the first light-emitting element is turned-off to increase the voltage instantly to make the blue-light brighter, thereby producing different light emitting effects according to different rotational ranges of the wrist training ball.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 1004079.8 filed in United Kingdom on Mar. 11, 2010, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a light-emitting control circuit, and more particularly to a light-emitting control circuit applied in a wrist training ball. 
     2. Related Art 
     A wrist training ball (as disclosed in U.S. Pat. No. 4,150,580) utilizes a gyroscopic principle and a strong force generated during rotation under the eccentric force and inertial effects, so that a trainer holds and rotates a ball body with a hand to exercise an arm and a wrist. The wrist training ball is widely applied in wrist strength exercises, especially exercises about holding strength of fingers, endurance of wrists, and muscle strength of forearms, biceps, triceps, ligaments, and shoulders. 
     In order to make the use of the wrist training ball become more interesting, light-emitting diodes (LEDs) for emitting light rays can be disposed on the wrist training ball. Coils and a magnet are disposed on the wrist training ball, and a magnetic field of the magnet is changed due to the rotation of the wrist training ball, such that the coils generate electric power, so as to supply the power to the LEDs for emitting light. Additionally, in order to produce various light emission effects, a programmable controller or a microprocessor is connected to a plurality of LEDs having different colors in a method of the prior art. Specific programs are written in the controller, and the LEDs are controlled to be turned on and off intermittently driven by logic programs, so as to produce various light emission effects (as disclosed in U.S. Pat. No. 7,101,315). 
     However, a plurality of LEDs and controllers are all loading for the circuit. The larger the loading is, the greater the resistance will be, thereby causing a lower brightness of the LED. In addition, the controller itself requires a great deal of electric power for operation. That is to say, most of the electric power generated by the induction coils is supplied to the controller, thereby resulting in the even lower brightness of the light rays emitted by the LED, so that the light ray effects become rather poor. 
     In addition, the programmable controller or the microprocessor has a higher cost than a common passive device. For example, the use of the programmable controller or the microprocessor greatly increases the manufacturing cost of the wrist training ball. 
     Therefore, in order to provide the wrist training ball with various light emission and flickering effects, the programmable controller or the microprocessor is adopted, which sacrifices the light emission intensity of the LEDs or increases the cost of the wrist training ball. 
     SUMMARY OF THE INVENTION 
     In a light emitting mode of a wrist training ball in the prior art, if a programmable controller or a microprocessor is used to control a plurality of LEDs to be turned on or off intermittently, the cost is increased or even the light emission intensity is decreased. In view of the above problems, the present invention is a light-emitting control circuit applied in a wrist training ball. 
     The present invention provides a light-emitting control circuit, which comprises a first transistor, a second transistor, a first resistor, a second resistor, a third resistor, a first LED, and a second LED. 
     The first transistor has a first node, a second node, and a control node. The second transistor has a first node, a second node, and a control node. The first resistor has a first node and a second node. The second resistor has a first node and a second node. The third resistor has a first node and a second node. The first LED has a first anode and a first cathode. The second LED has a second anode and a second cathode. 
     The first node of the second transistor, the first node of the first resistor, and the first node of the second resistor receive a voltage source. The first node of the first transistor is electrically connected to the second node of the first resistor. The second node of the first transistor is electrically connected to the first anode of the first LED. The control node of the first transistor is electrically connected to the first node of the third resistor and the second node of the second transistor. The control node of the second transistor is electrically connected to the second node of the second resistor and the second anode of the second LED. The first cathode of the first LED, the second cathode of the second LED, and the second node of the third resistor are grounded. 
     The present invention provides a light-emitting device, which comprises an electricity generating circuit and a light-emitting control circuit. The electricity generating circuit comprises an induction coil, a rectifier and filter circuit. The induction coil is used for receiving an induced voltage. The rectifier and filter circuit is used for converting the induced voltage into an output voltage. The light-emitting control circuit is the same as the light-emitting control circuit discussed above. 
     The present invention provides a wrist training ball, which comprises a shell and a rotating ball. The rotating ball is located inside the shell. The above light-emitting device is disposed on the rotating ball. The light-emitting device comprises an electricity generating circuit and a light-emitting control circuit. A voltage received by the light-emitting control circuit is generated by the electricity generating circuit of the wrist training ball. A voltage value of the electricity generating circuit varies according to a rotating speed for rotating the wrist training ball, so that the first light-emitting element and the second light-emitting element form three light emission aspects corresponding to a low-level rotating speed, a mid-level rotating speed, and a high-level rotating speed respectively, so as to represent rotating speed ranges that a user rotates the wrist training ball. In addition, through the present invention, the cost of the light-emitting control circuit can be effectively reduced and a load of the light-emitting control circuit is decreased, thereby increasing brightness of light rays of the LEDs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below for illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1A  is an equivalent circuit diagram of a first embodiment of a light-emitting control circuit; 
         FIG. 1B  is an equivalent circuit diagram of a second embodiment of a light-emitting control circuit; 
         FIG. 1C  is an equivalent circuit diagram of a third embodiment of a light-emitting control circuit; 
         FIG. 1D  is an equivalent circuit diagram of a fourth embodiment of a light-emitting control circuit; 
         FIG. 1E  is an equivalent circuit diagram of a fifth embodiment of a light-emitting control circuit; 
         FIG. 2A  is an equivalent circuit diagram of a first embodiment of an electricity generating circuit; 
         FIG. 2B  is an equivalent circuit diagram of a second embodiment of an electricity generating circuit; 
         FIG. 2C  is an equivalent circuit diagram of a third embodiment of an electricity generating circuit; 
         FIG. 2D  is an equivalent circuit diagram of a fourth embodiment of an electricity generating circuit; 
         FIG. 3A  is a structural three-dimensional outside view of a wrist training ball; 
         FIG. 3B  is an exploded three-dimensional outside view of a wrist training ball; 
         FIG. 3C  is a detailed exploded three-dimensional outside view of a wrist training ball; 
         FIG. 3D  is a detailed exploded three-dimensional outside view of a wrist training ball; and 
         FIG. 4  is a relation diagram between a rotating speed of a rotating ball and a voltage. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Detailed features and advantages of the present invention are illustrated below in detail in the detailed description, the content of which is sufficient for any person skilled in the art to understand technical contents of the present invention and implement the present invention accordingly. In addition, according to the content disclosed in the specification, claims, and accompanying drawings, any person skilled in the art can easily understand related objectives and advantages of the present invention. 
       FIG. 1A  is an equivalent circuit diagram of a first embodiment of a light-emitting control circuit. Referring to  FIG. 1A , a light-emitting control circuit  100  comprises a first transistor  112 , a second transistor  114 , a first resistor  122 , a second resistor  124 , a third resistor  126 , a first LED  132 , and a second LED  134 . The light-emitting control circuit  100  receives a voltage source (voltage Vcc) and determines whether to turn on the first LED  132  and the second LED  134  according to a voltage value of the voltage Vcc. 
     The first transistor  112  has a first node, a second node, and a control node. The second transistor has a first node, a second node, and a control node. In this embodiment, the first transistor  112  may be a PNP bipolar junction transistor (BJT). The first node of the first transistor is a first emitter  112   e . The second node of the first transistor is a first collector  112   c . The control node of the first transistor is a first base  112   b . The first node of the second transistor is a second emitter  114   e . The second node of the second transistor is a second collector  114   c . The control node of the second transistor is a second base  114   b.    
     The first resistor  122  has a first node  122   a  and a second node  122   b . The second resistor  124  has a first node  124   a  and a second node  124   b . The third resistor  126  has a first node  126   a  and a second node  126   b.    
     The first LED  132  has a first anode  132   a  and a first cathode  132   b . The second LED  134  has a second anode  134   a  and a second cathode  134   b . When a voltage difference between the first anode  132   a  and the first cathode  132   b  is greater than a forward bias of the first LED  132 , the first LED  132  is turned on. The second LED  134  also has the same phenomenon. When being turned on, the first LED  132  and the second LED  134  emit light rays with different colors, and a forward bias of the second LED  134  is greater than the forward bias of the first LED  132 . For example, the first LED  132  emits red light and the second LED  134  emits blue light. Besides the above colors, the first LED  132  and the second LED  134  may also emit light rays with other colors. For example, the first LED  132  emits orange light and the second LED  134  emits white light. In other words, as long as the forward bias of the second LED  134  is greater than the forward bias of the first LED  132 , it falls within the scope of the present invention. 
     The first node  122   a  of the first resistor  122  and the first node  124   a  of the second resistor  124  are used for receiving the voltage Vcc. 
     The first emitter  112   e  is electrically connected to the second node  122   b  of the first resistor  122 . The first base  112   b  is electrically connected to the third resistor  126 . The first collector  112   c  is electrically connected to the first LED  132 . 
     The second emitter  114   e  is used for receiving the voltage Vcc. The second base  114   b  is electrically connected to the second node  124   b  of the second resistor  124  and the second LED  134 . The second collector  114   c  is electrically connected to the first base  112   b  and the first node  126   a  of the third resistor  126 . 
     The first cathode  132   b , the second cathode  134   b , and the second node  126   b  of the third resistor  126  are grounded. 
     When the voltage Vcc is smaller than a first threshold value, neither the first LED  132  nor the second LED  134  is turned on. When the voltage Vcc exceeds the first threshold value, the voltage Vcc is sufficient for turning on the first LED  132 , and the first LED  132  emits red light. The first threshold value approximately equals the forward bias of the first LED  132  plus a voltage across the first emitter  112   e  and the first collector  112   c  plus a voltage across the first resistor  122 . 
     When the voltage Vcc continues to increase and exceeds a second threshold value, that is, the voltage Vcc is sufficient for turning on the second LED  134 , the second LED  134  emits blue light, and the first LED  132  still keeps emitting red light. The voltage Vcc at this time approximately equals a voltage across the second resistor  124  plus the forward bias of the second LED  134 . 
     When the voltage Vcc continues to increase and exceeds a third threshold value, that is, the voltage across the second resistor  124  is greater than a critical voltage of the second transistor  114 , the second transistor  114  is turned on. At this time, the current flows to the third resistor  126  through the second transistor  114 , so that the voltage across the two nodes of the third resistor  126  is dramatically increased, that is, the voltage between the first emitter  112   e  and the first base  112   b  of the first transistor  112  is greatly decreased. Therefore, the first transistor  112  is cut off. At this time, the second LED  134  keeps emitting light. However, the first LED  132  is turned off. In other words, only the second LED  134  emits blue light individually. 
     When the first LED  132  is turned off, the load of the light-emitting control circuit  100  is decreased, which makes the second LED  134  become brighter. 
       FIG. 1B  is an equivalent circuit diagram of a second embodiment of a light-emitting control circuit. Although the above structure only has one first LED  132  and one second LED  134 , the present invention is not limited thereto. In order to enhance the light emission brightness or the aesthetic feeling in design, more first LEDs  132  and second LEDs  134  may be disposed. Specifically, two first LEDs  132 ,  132 ′ may be connected in parallel. The first anodes  132   a ,  132   a ′ of the first LEDs  132 ,  132 ′ are connected to the first collector  112   c  together. The first cathodes  132   b ,  132   b ′ of the first LEDs  132 ,  132 ′ are both grounded. Two second LEDs  134 ,  134 ′ may also be connected in parallel. The second anodes  134   a ,  134   a ′ of the second LEDs  134 ,  134 ′ are connected to the second node  124   b  of the second resistor  124  together. The second cathodes  134   b ,  134   b ′ of the second LED  134 ,  134 ′ are both grounded. 
       FIG. 1C  is an equivalent circuit diagram of a third embodiment of a light-emitting control circuit. Besides the above connection modes, persons skilled in the art can connect more first LEDs  132  and second LEDs  134  according to the spirit of the present invention. Specifically, three first LEDs  132 ,  132 ′,  132 ″ may be connected in parallel. The first anodes  132   a ,  132   a ′,  132   a ″ of the first LEDs  132 ,  132 ′,  132 ″ are connected to the first collector  112   c  together. The first cathodes  132   b ,  132   b ′,  132   b ″ of the first LEDs  132 ,  132 ′,  132 ″ are all grounded. Three second LEDs  134 ,  134 ′,  134 ″ may also be connected in parallel. The second anodes  134   a ,  134   a ′,  134   a ″ of the second LEDs  134 ,  134 ′,  134 ″ are connected to the second node  124   b  of the second resistor  124  together. The second cathodes  134   b ,  134   b ′,  134   b ″ of the second LEDs  134 ,  134 ′,  134 ″ are all grounded. 
       FIG. 1D  is an equivalent circuit diagram of a fourth embodiment of a light-emitting control circuit. Although the first transistor  112  and the second transistor  114  are PNP BJTs, persons skilled in the art may replace the PNP BJTs with P-type metal oxide semiconductors (MOSs) according to the spirit of this embodiment. In this embodiment, the P-type MOS replaces the PNP BJT. That is to say, a first source  112   s  is equivalent to the first emitter  112   e , a first gate  112   g  is equivalent to the first base  112   b , and a first drain  112   d  is equivalent to the first collector  112   c . Similarly, a second source  114   s  is equivalent to the second emitter  114   e , a second gate  114   g  is equivalent to the second base  114   b , and a second drain  114   d  is equivalent to the second collector  114   c . In addition, other elements of the light-emitting control circuit  100  are the same as that shown in  FIG. 1A . Such a method can also be used in both  FIGS. 1B and 1C . 
       FIG. 1E  is an equivalent circuit diagram of a fifth embodiment of a light-emitting control circuit. In this embodiment, the second resistor  124  may be a variable resistor. By changing a resistance value of the variable resistor, the third threshold value can be adjusted. When the resistance value of the variable resistor becomes smaller, a higher voltage Vcc is required to turn on the second transistor  114 , that is, the third threshold value becomes higher. On the contrary, the larger the resistance value of the variable resistor is, the lower the third threshold value will be. If the third threshold value becomes higher, it indicates that a higher rotating speed is required to enable the second LED  134  to emit blue light individually. That is to say, the user can change the threshold value for the emission of blue light by adjusting the resistance value of the variable resistor. The variable resistor is applicable to any embodiment in  FIGS. 1A to 1D . 
     The light-emitting control circuit  100  according to the present invention determines whether to turn on the first LED  132  and the second LED  134  according to a voltage value of the voltage Vcc. The light-emitting control circuit  100  can replace the programmable controller or microprocessor in the prior art. In addition, the light-emitting control circuit  100  only requires two transistors (BJTs or MOSs) and three resistors. Therefore, the cost of the light-emitting control circuit  100  is much lower than that of the programmable controller or microprocessor in the prior art. In addition, the light-emitting control circuit  100  uses quite a few elements, so that the consumption of electric power is much lower than that of the programmable controller or microprocessor in the prior art. When the same power supply is input, the brightness of light rays emitted by the LEDs driven by the light-emitting control circuit  100  according to the present invention is much higher than that of light rays emitted by the LEDs driven by the programmable controller or microprocessor. 
       FIG. 2A  is an equivalent circuit diagram of a first embodiment of an electricity generating circuit. The electricity generating circuit  200  comprises an induction coil  211  and a rectifier and filter circuit. The rectifier and filter circuit comprises a rectifier diode  221  and a filter capacitor  231 . 
     The induction coil  211  may be an inductor. When the relative movement is generated between the induction coil  211  and a magnetic element (for example, a magnet), a magnetic field received by the induction coil  211  is changed, so that the induction coil  211  generates an induced voltage. When the magnetic field changed by the induction coil  211  is a sine function, the induced voltage is an alternating current (AC) voltage. 
     The rectifier diode  221  is used for converting the AC voltage into a direct current (DC) voltage. In this embodiment, when only one rectifier diode  221  is configured, the circuit may be called a half-wave rectifier. 
     Persons skilled in the art can use a full-wave rectifier to replace the above half-wave rectifier.  FIG. 2B  is an equivalent circuit diagram of a second embodiment of an electricity generating circuit. In this embodiment, the electricity generating circuit  200  comprises four rectifier diodes  221 ,  222 ,  223 ,  224 . When the induced voltage is a positive voltage, the current passes through the rectifier diodes  221 ,  224  and the filter capacitor  231 . When the induced voltage is a negative voltage, the current passes through the rectifier diodes  222 ,  223  and the filter capacitor  231 . 
     In addition, a center-tapped rectifier may also be used to replace the half-wave rectifier.  FIG. 2C  is an equivalent circuit diagram of a third embodiment of an electricity generating circuit. The electricity generating circuit  200  comprises two rectifier diodes  221 ,  222 . When the induced voltage is a positive voltage, the current generated by an upper half end of the induction coil  211  passes through the rectifier diode  221  and the filter capacitor  231 . When the induced voltage is a negative voltage, the current generated by a lower half end of the induction coil  211  passes through the rectifier diode  222  and the filter capacitor  231 . 
       FIG. 2D  is an equivalent circuit diagram of a fourth embodiment of an electricity generating circuit. Although the electricity generating circuit  200  in  FIGS. 2A ,  2 B, and  2 C only comprises a filter capacitor  231 , persons skilled in the art can connect a filter resistor  232  with the filter capacitor  231  in parallel, so as to achieve the better filtering effect. 
     Through the above induction coil  211 , the rectifier diode  221 , and the filter capacitor  231 , the electricity generating circuit  200  generates a DC voltage Vcc and supplies the DC voltage Vcc to the light-emitting control circuit  100 , and the light-emitting control circuit  100  emits light rays with different colors according to a value of the voltage Vcc. 
     The light-emitting control circuit  100  and the electricity generating circuit  200  are applicable to various rotational devices, for example, the wrist training ball according to the present invention. However, the present invention is not limited thereto. The light-emitting device according to the present invention can be applied to all rotational devices such as bicycles, in-line skates, or yo-yos. Rotation energy produced by the rotation movement can be converted into electric power. The higher the rotating speed is, the higher the voltage value of the electric power will be. The light-emitting device according to the present invention can determine to emit light rays having different colors according to the voltage value, that is, according to the rotating speed. 
       FIGS. 3A and 3B  show a wrist training ball using the above light-emitting device.  FIG. 3A  is a structural three-dimensional outside view of a wrist training ball.  FIG. 3B  is an exploded three-dimensional outside view of a wrist training ball. Referring to  FIGS. 3A and 3B , a wrist training ball  300  comprises a shell  310  and a rotating ball  350 . 
     The shell  310  comprises an upper shell body  320  and a lower shell body  330 . An opening is opened at a top end of the upper shell body  320 . The upper shell body  320  and the lower shell body  330  are configured into approximately hollow hemispheric shell bodies. The upper shell body  320  and the lower shell body  330  may be combined together to form a hollow space. The upper shell body  320  and the lower shell body  330  may be colored transparent shell bodies. As the above first LED  132  and second LED  134  are turned on or off, the transparent shell bodies are turned to show various different colors accordingly. 
     An outer ring  340  is placed between a lower edge of the upper shell body  320  and an upper edge of the lower shell body  330 , and a rotating shaft hole  342  is opened at each end of the outer ring  340  respectively. A magnetic element  344  is fixed on the outer ring  340 . The magnetic element  344  may be, but not limited to, a magnet. 
     The rotating ball  350  is located within the hollow space formed by the upper shell body  320  and the lower shell body  330 . Two sides of the rotating ball  350  respectively have a rotating shaft  352 . The two rotating shafts  352  can penetrate into the rotating shaft holes  342  respectively. The rotating ball  350  rotates about an axis along which the rotating shafts  352  extend. 
     Referring to  FIG. 3C , a circuit board  360  is disposed on the rotating ball  350 . The above light-emitting control circuit  100  and the electricity generating circuit  200  are disposed on the circuit board  360 . The first LED  132  and the second LED  134  of the light-emitting control circuit  100  stand vertically on the circuit board  360 . The first LED  132  and the second LED  134  may penetrate through the through holes in the center of the rotating ball  350 . Elements  221 ,  221 ′ can rotate relative to the magnetic element  344  to generate an induced voltage, which is rectified and filtered into a voltage Vcc. The voltage Vcc is supplied to the light-emitting control circuit  100 . The light-emitting control circuit  100  controls the first LED  132  or the second LED  134  according to a voltage value of the voltage Vcc. That is to say, the wrist training ball  300  emits different light rays according to different rotating speeds. 
     Referring to  FIG. 3D , two first LEDs  132 ,  132 ′ and two second LEDs  134 ,  134 ′ are disposed on the circuit board  360 . The two first LEDs  132 ,  132 ′ and the two second LEDs  134 ,  134 ′ can be further understood with reference to  FIG. 1B , the description of which is omitted here. 
       FIG. 4  is a relation diagram between a rotating speed of a rotating ball and a voltage. In  FIG. 4 , a transverse axis represents the rotating speed of the rotating ball and a longitudinal axis represents the voltage Vcc. 
     When the wrist training ball  300  stays still, that is, the rotating speed of the rotating ball  350  is zero, the voltage Vcc is a zero voltage. When the rotating speed of the rotating ball  350  as a rotating object gradually increases, the voltage Vcc also gradually increases. 
     When the rotating speed of the rotating ball  350  keeps rising and reaches a low-level rotating speed, that is, the voltage Vcc exceeds a first threshold value, the voltage Vcc is sufficient for turning on the first LED  132 . 
     When the rotating speed of the rotating ball  350  continues to rise and reaches a mid-level rotating speed, that is, the voltage Vcc exceeds a second threshold value, the voltage Vcc is sufficient for turning on the second LED  134 , and the second LED  134  emits blue light and the first LED  132  still keeps emitting red light. Since the first LED  132  and the second LED  134  emit red light and blue light at the same time, under a visual persistence phenomenon generated through high-speed rotation, the light-emitting device seems to emit purple light between the red light and the blue light. 
     When the rotating speed of the rotating ball  350  rises ceaselessly and reaches a high-level rotating speed, that is, the voltage Vcc exceeds a third threshold value, a voltage across the second resistor  124  becomes greater than a critical voltage of the second transistor  114 , and the second transistor  114  is turned on, so that the first transistor  112  is cut off. At this time, the first LED  132  is turned off. However, the second LED  134  keeps emitting light. In other words, only the second LED  134  emits blue light individually. 
     When the first LED  132  is turned off, the load of the light-emitting control circuit  100  is decreased, so that the voltage Vcc is increased instantly and the second LED  134  becomes brighter. As the voltage Vcc is increased instantly, the voltage across the second resistor  124  is also increased at the same proportion. That is to say, the voltage across the second resistor  124  at this time is far greater than the critical voltage of the second transistor  114 . Therefore, even if the rotating speed of the rotating ball  350  starts to slow down, the second transistor  114  is still turned on, and the second LED  134  keeps emitting blue light. 
     When the rotating speed of the rotating ball  350  keeps dropping and the voltage Vcc becomes lower than a fourth threshold value, that is, the voltage Vcc is not sufficient for turning on the second LED  134 , the second LED  134  no longer emits light. Meanwhile, the second transistor  114  is cut off, and the first transistor  112  is turned on, so that the first LED  132  is turned on and emits light. That is to say, the original blue light emitted by the second LED  134  is directly changed into the red light emitted by the first LED  132 . 
     The wrist training ball according to the present invention can emit red light at a low-level rotating speed, emit purple light at a mid-level rotating speed, and emit blue light at a high-level rotating speed, so that the user is enabled to know a current rotating speed range according to the emitted light rays.