Patent ID: 12213233

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. It should be understood that, when it is described that an element is “coupled” or “connected” to another element, the element may be “directly coupled” or “directly connected” to the other element or “coupled” or “connected” to the other element through a third element. In contrast, it should be understood that, when it is described that an element is “directly coupled” or “directly connected” to another element, there are no intervening elements.

Please refer toFIG.1, which is the block diagram of the circuit structure of a lighting device having resettable over-current protection function in accordance with one embodiment of the present invention. As shown inFIG.1, the lighting device1includes a light source module13, a power supplying module11, a DC (direct-current)-to-DC converting module12, an over-current short-circuit protection module14, a self-locking protection module15, an integral module16, and a reference voltage generating module17. The combination of the over-current short-circuit protection module14, the reference voltage generating module17, the self-locking protection module15and the integral module16can form a resettable over-current protection circuit SRP. The lighting device1can be a portable lighting device, such as a flashlight, handheld searchlight, handheld work light, headlamp, etc.

The DC-to-DC converting module12is connected to the power supplying module11. In this embodiment, the DC-to-DC converting module12is a buck-boost converter. The DC-to-DC converting module12includes a control chip Sp, an energy storage inductor Lp, a boost diode Dp and a filter capacitor Cp. The circuit structure and operating mechanism of the DC-to-DC converting module12should be known by those skilled in the art, so will not be described herein. In another embodiment, the DC-to-DC converting module12can be a buck converter, boost converter, or other similar components. In one embodiment, the power supplying module11can be a Li-ion battery, a Ni—Cd battery, a Ni—MH battery, a zinc-carbon battery or other DC power sources.

The light source module13is connected to the DC-to-DC converting module12. In one embodiment, the light source module13can be a light-emitting diode (LED), several LEDs connected in series, an LED array, a bulb, or similar components.

The over-current short-circuit protection module14is connected to the light source module13. The self-locking protection module15is connected to the over-current short-circuit protection module14and the power supplying module11. The integral module16is connected to the self-locking protection module15. The reference voltage generating module17is connected to the power supplying module11, the self-locking protection module15, and the over-current short-circuit protection module14.

The embodiment just exemplifies the present invention and is not intended to limit the scope of the present invention; any equivalent modification and variation according to the spirit of the present invention is to be also included within the scope of the following claims and their equivalents.

Please refer toFIG.2, which is the schematic view of the operating state of the lighting device having resettable over-current protection function in accordance with one embodiment of the present invention. As shown inFIG.2, the power supplying module11generates an input voltage Vin.

Then, the DC-to-DC converting module12converts the input voltage Vin into generate a driving voltage Vd and outputs the driving voltage Vd to the light source module13so as to drive the light source module13.

Next, the over-current short-circuit protection module14detects the driving current Cd through the light source module13to generate a voltage detection signal Vm.

Afterward, the reference voltage generating module17generates a reference voltage Vf according to the input voltage Vin and the voltage detecting signal Vm.

Finally, the self-locking protection module15generates a control signal Cs based on the input voltage Vin and the reference voltage Vf to turn off the over-current short-circuit protection module14with a view to executing the self-locking protection mode. When the self-locking protection module15executes the self-locking protection mode, the self-locking protection module15can disconnect the connection between the DC-to-DC converting module12and the light source module13in order to make the lighting device1enter the over-current short-circuit protection state.

In addition, the integral module16can generate an integral signal Ts according to the voltage detecting signal Vm and output the integral signal Ts to the self-locking protection module15. Therefore, the self-locking protection module15can continuously maintain the self-locking protection mode, such that the lighting device1can remain in the over-current short-circuit protection state.

The embodiment just exemplifies the present invention and is not intended to limit the scope of the present invention; any equivalent modification and variation according to the spirit of the present invention is to be also included within the scope of the following claims and their equivalents.

The lighting device1has the resettable over-current protection circuit SRP, which can function as the self-locking over-current protection circuit to execute the self-locking protection mode so as to provide the over-current protection function. When the fault is resolved, simply reconnecting the power supplying module11can automatically turn off the self-locking protection mode to prevent fault expansion and avoid that the lighting device1is damaged.

The aforementioned resettable over-current protection circuit SRP can be applied to most portable lighting devices and can effectively execute the self-locking protection mode to provide the over-current protection function without being limited by the duty cycle of PWM signals. Additionally, the resettable over-current protection circuit SRP can prevent the lighting device1from repeatedly restarting. Therefore, the application of the resettable over-current protection circuit SRP can be more comprehensive and significantly enhances the safety of the lighting device1.

The resettable over-current protection circuit SRP includes the integral module16, which can enhance the anti-interference ability of the resettable over-current protection circuit SRP. In this way, the resettable over-current protection circuit SRP can normally operate without being influenced by interferences duo to different factors. Consequently, the performance of the resettable over-current protection circuit SRP can be significantly improved, so the lighting device1can achieve high safety.

The embodiment just exemplifies the present invention and is not intended to limit the scope of the present invention; any equivalent modification and variation according to the spirit of the present invention is to be also included within the scope of the following claims and their equivalents.

It is worthy to point out that most currently available portable lighting devices have short-circuit protection mechanisms, such as fuses, comparator lockout protection s with amplifiers, and resettable fuses. However, these short-circuit protection mechanisms still have many shortcomings, so these short-circuit protection mechanisms need to be further improved. On the contrary, according to one embodiment of the present invention, the lighting device includes a resettable over-current protection circuit, which can function as a self-locking over-current protection circuit to execute a self-locking protection mode for providing the over-current protection function. When the fault is resolved, simply reconnecting the power supplying module can automatically turn off the self-locking protection mode to prevent fault expansion and avoid that the lighting device is damaged.

Also, according to one embodiment of the present invention, the resettable over-current protection circuit can be applied to most portable lighting devices and can effectively execute the self-locking protection mode to provide the over-current protection function without being limited by the duty cycle of pulse width modulation (PWM) signals. Additionally, the resettable over-current protection circuit can prevent the lighting device from repeatedly restarting. Therefore, the application of the resettable over-current protection circuit can be more comprehensive and significantly enhances the safety of the lighting device.

Further, according to one embodiment of the present invention, the resettable over-current protection circuit of the lighting device can execute the self-locking protection mode to provide the over-current protection function. Furthermore, once in the self-locking protection mode, the resettable over-current protection circuit does not produce large currents. As a result, the service life of the power supplying module is not reduced due to overload, which can extend the service life of the lighting device and meet the requirements of environmental protection.

Moreover, according to one embodiment of the present invention, all of the circuit components of the resettable over-current protection circuit of the lighting device can be hardware circuit components and can effectively execute the self-locking protection mode. Therefore, the resettable over-current protection circuit can achieve high reliability so as to conform to actual requirements.

Furthermore, according to one embodiment of the present invention, the resettable over-current protection circuit of the lighting device includes an integral module, which can enhance the anti-interference ability of the resettable over-current protection circuit. In this way, the resettable over-current protection circuit can normally operate without being influenced by interferences duo to different factors. Consequently, the performance of the resettable over-current protection circuit can be significantly improved, so the lighting device can achieve high safety. As set forth above, the lighting device having resettable over-current protection function according to the embodiments can definitely achieve great technical effects.

Please refer toFIG.3, which is the circuit diagram of the circuit structure of the lighting device having resettable over-current protection function in accordance with one embodiment of the present invention. Please also refer toFIG.1andFIG.2. This embodiment illustrates the detailed circuit structure of the lighting device1. As shown inFIG.3, the lighting device1includes the power supplying module11, the DC-to-DC converting module12, the light source module13and the resettable over-current protection circuit SRP. As described above, the resettable over-current protection circuit SRP includes the over-current short-circuit protection module14, the reference voltage generating module17, the self-locking protection module15and the integral module16(as shown inFIG.1andFIG.2). In this embodiment, the light source module13includes a plurality of LEDS LD1˜LD3.

The power supplying module11has a power source positive electrode V+ and a power source negative electrode V−. As mentioned earlier, the power supplying module11can be a battery or a DC power source.

The DC-to-DC converting module12includes a control chip Sp, an energy storage inductor Lp, a boost diode Dp and a filter capacitor Cp. The control chip Sp includes a signal generator Pg and a control transistor Qs. The circuit structure and operating mechanism of the DC-to-DC converting module12should be known by those skilled in the art and will not be not described herein. The DC-to-DC converting module12has an input terminal E1, a first output terminal E2, and a second output terminal E3. The input terminal E1of the DC-to-DC converting module12is connected to the power source positive electrode V+ of the power supplying module11. The first output terminal E2of the DC-to-DC converting module12is connected to the positive electrode of the light source module13. The second output terminal E3of the DC-to-DC converting module12is connected to the first node N1and the grounding point GND. The negative electrode of the light source module13is connected to the second node N2.

The resettable over-current protection circuit SRP includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a diode ZD, and a first capacitor C1. In this embodiment, the first transistor Q1, the second transistor Q2, and the third transistor Q3are metal-oxide-semiconductor field-effect transistors (MOSFETs). In another embodiment, the first transistor Q1, the second transistor Q2, and the third transistor Q3can also be bipolar junction transistors (BJTs) or other similar components. In this embodiment, the diode ZD can be a Zener diode. In another embodiment, the diode ZD can also be a three-terminal voltage regulator or other similar components.

The first end (gate) of the first transistor Q1is connected to the third node N3, the second end (drain) of the first transistor Q1is connected to the second node N2, and the third end (source) of the first transistor Q1is connected to the fourth node N4. The first end (gate) of the second transistor Q2is connected to the fifth node N5, the second end (drain) of the second transistor Q2is connected to the third node N3, and the third end (source) of the second transistor Q2is connected to the sixth node N6. The first end (gate) of the third transistor Q3is connected to the sixth node N6, the second end (drain) of the third transistor Q3is connected to one end of the fifth resistor R5, and the third end (source) of the third transistor Q3is connected to the fifth node N5(in this embodiment, the first transistor Q1, the second transistor Q2, and the third transistor Q3are all n-channel MOSFETs). The other end of the fifth resistor R5is connected to the seventh node N7, and the seventh node N7is connected to the power source positive electrode V+ of the power supplying module11. The two ends of the second resistor R2are connected to the seventh node N7and the eighth node N8. The two ends of the first resistor R1are connected to the fifth node N5and the eighth node N8respectively. The two ends of the third resistor R3are connected to the first node N1and the fourth node N4respectively. The two ends of the fourth resistor R4are connected to the second node N2and the third node N3respectively. The two ends of the sixth resistor R6are connected to the fourth node N4and the fifth node N5respectively. The two ends of the seventh resistor R7are connected to the first node N1and the sixth node N6respectively. The two ends of the first capacitor C1are connected to the first node N1and the fifth node N5respectively. The two ends of the diode ZD are connected to the first node N1and the eighth node N8respectively.

When the light source module13is not connected to the DC-to-DC converting module12and the resettable over-current protection circuit SRP, the gate voltage of the second transistor Q2can be expressed by Equation (1) given below:
Vg2=(r3+r6)/(r1+r3+r6)*Vzd(1)

In Equation (1), Vg2stands for the gate voltage of the second transistor Q2; r1stands for the resistance of the first resistor R1; r3stands for the resistance of the third resistor R3; r6stands for the resistance of the sixth resistor R6; Vzd stands for the voltage across the diode.

When the light source module13is connected to the DC-to-DC converting module12and the resettable over-current protection circuit SRP, the driving current Cd passes through the first transistor Q1and the third resistor R3to reach the power source negative electrode V− of the power supplying module11. At this time, a potential difference is generated across the two ends of the third resistor R3, causing an increase in the gate voltage of the second transistor Q2.

When the driving current Cd continues to increase, the potential difference across the two ends of the third resistor R3also continues to increase, which makes the gate voltage of the second transistor Q2continuously increase. When the gate voltage of the second transistor Q2continues to increase to the gate threshold voltage, the second transistor Q2is turned on (the maximal load current can be calculated from the above mechanism). At the same time, the gate voltage of the first transistor Q1decreases, which makes the first transistor Q1be turned off.

Then, as the second transistor Q2is turned on, the potential difference across the two ends of the seventh resistor R7quickly rises, causing an increase in the gate voltage of the third transistor Q3. When the gate voltage of the third transistor Q3increases to the gate threshold voltage, the third transistor Q3is turned on. At this time, the power supplying module11can provide voltage to the gate of the second transistor Q2through the fifth resistor R5and the third transistor Q3, which makes the second transistor Q2continuously remain the on state.

On the other hand, the integral module16, including the third resistor R3, the sixth resistor R6, and the first capacitor C1, can enhance the anti-interference ability of the resettable over-current protection circuit SRP to prevent the second transistor Q2from incorrectly operating. Therefore, the operation of the resettable over-current protection circuit SRP is less susceptible to interference. Additionally, when the driving current Cd decreases to its normal value or zero, the first capacitor C1of the integral module16can provide voltage to the gate of the second transistor Q2to make the second transistor Q2remain the on state until the third transistor Q3is turned on, such that the power supplying module11can apply voltage to the gate of the second transistor Q2. As previously stated, it can be seen that the resettable over-current protection circuit SRP can provide dual protection mechanisms to ensure that the second transistor Q2is always in the on state in the self-locking protection mode, which can effectively perform the self-locking protection mode.

In this way, the self-locking protection mode can be automatically turned off when the user separates the power supplying module11from the lighting device11. Thus, the user does not need to repair the lighting device1, which is more convenient in use. Accordingly, the lighting device1can conform to actual requirements. When the fault is resolved, simply reconnecting the power supplying module11can automatically turn off the self-locking protection mode to prevent fault expansion and avoid that the lighting device1is damaged.

Further, the resettable over-current protection circuit SRP of the lighting device1can execute the self-locking protection mode to provide the over-current protection function. Furthermore, once in the self-locking protection mode, the resettable over-current protection circuit SRP does not produce large currents. As a result, the service life of the power supplying module11is not reduced due to overload, which can extend the service life of the lighting device1and meet the requirements of environmental protection.

Moreover, as described above, all of the circuit components of the resettable over-current protection circuit SRP of the lighting device1can be hardware circuit components and can effectively execute the self-locking protection mode. Therefore, the resettable over-current protection circuit SRP can achieve high reliability so as to conform to actual requirements.

The embodiment just exemplifies the present invention and is not intended to limit the scope of the present invention; any equivalent modification and variation according to the spirit of the present invention is to be also included within the scope of the following claims and their equivalents.

To sum up, according to one embodiment of the present invention, the lighting device includes a resettable over-current protection circuit, which can function as a self-locking over-current protection circuit to execute a self-locking protection mode for providing the over-current protection function. When the fault is resolved, simply reconnecting the power supplying module can automatically turn off the self-locking protection mode to prevent fault expansion and avoid that the lighting device is damaged.

Also, according to one embodiment of the present invention, the resettable over-current protection circuit can be applied to most portable lighting devices and can effectively execute the self-locking protection mode to provide the over-current protection function without being limited by the duty cycle of pulse width modulation (PWM) signals. Additionally, the resettable over-current protection circuit can prevent the lighting device from repeatedly restarting. Therefore, the application of the resettable over-current protection circuit can be more comprehensive and significantly enhances the safety of the lighting device.

Further, according to one embodiment of the present invention, the resettable over-current protection circuit of the lighting device can execute the self-locking protection mode to provide the over-current protection function. Furthermore, once in the self-locking protection mode, the resettable over-current protection circuit does not produce large currents. As a result, the service life of the power supplying module is not reduced due to overload, which can extend the service life of the lighting device and meet the requirements of environmental protection.

Moreover, according to one embodiment of the present invention, all of the circuit components of the resettable over-current protection circuit of the lighting device can be hardware circuit components and can effectively execute the self-locking protection mode. Therefore, the resettable over-current protection circuit can achieve high reliability so as to conform to actual requirements.

Furthermore, according to one embodiment of the present invention, the resettable over-current protection circuit of the lighting device includes an integral module, which can enhance the anti-interference ability of the resettable over-current protection circuit. In this way, the resettable over-current protection circuit can normally operate without being influenced by interferences duo to different factors. Consequently, the performance of the resettable over-current protection circuit can be significantly improved, so the lighting device can achieve high safety.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the present invention being indicated by the following claims and their equivalents.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.