TWI458389B - Dynamically adjusting dimming range driving apparatus and method thereof - Google Patents

Description

Driving device capable of dynamically adjusting dimming range and operating method thereof

The invention relates to a dimmable light-emitting diode driving device and an operating method thereof, and in particular to a light-emitting diode driving device capable of dynamically adjusting a dimming range and an operating method thereof.

The brightness of the light-emitting diode is mainly determined by the current of the input light-emitting diode. In the prior art, in order to adjust the light-emitting brightness of the light-emitting diode, a dimmer can be used to input the AC power of the mains. After the phase modulation is performed, a phase modulation AC power source is output to control the brightness of the LED.

Generally used for dimming devices on lamps, most of them use thyristor to perform phase control to change the size of the conductive angle to control the brightness of the LED. If the voltage level obtained after the phase modulation is small, the current input to the light-emitting diode is relatively small, thereby reducing the brightness of the light-emitting diode; if the voltage level obtained is increased, the current can be increased. The brightness of the light-emitting diode.

In the conventional art, a light-emitting diode driver that performs a phase dimming function uses a capacitor of a fixed capacitance to determine a duty cycle of an output pulse signal. Since the capacitance is fixed, once the dimming to the voltage level is small, the current ripple to the LED is large, which may result in unstable light output of the LED and flickering. In addition, the fixed capacity will result in limited dimming range.

Therefore, how to improve the shortcomings of the above-described light-emitting diode driving circuit has become a goal.

The invention mainly provides a dynamic adjustment of the capacitance value of the power factor control unit, so that the dimmer is not limited by the fixed capacitance value of the power factor control unit when performing the brightness adjustment, and the overall dimming range can be expanded.

According to an aspect of the present invention, a driving device capable of dynamically adjusting a dimming range is provided, and at least includes: a dimming unit configured to modulate an alternating voltage and rectify the modulated alternating current into a first a DC drive voltage; a voltage conversion unit that converts the first DC drive voltage into a second DC drive voltage according to an on-time; an illumination unit that emits light according to the second DC drive voltage; and a power factor control unit And controlling the on-time, wherein when the first DC driving voltage is greater than a threshold voltage, the power factor control unit controls the conduction time according to a first capacitance value, and when the first DC driving voltage is less than At the threshold voltage value, the power factor control unit controls the conduction time according to a second capacitance value, wherein the second capacitance value is less than the first capacitance value.

In an embodiment, a feedback unit is further included, and the illumination result of the illumination unit is returned to the power factor control unit for controlling the conduction time.

In an embodiment, the method further includes a first capacitor and a second capacitor. When the first DC driving voltage is greater than the threshold voltage, the first capacitor is connected in parallel with the second capacitor to provide the first capacitor value control. The on-time, and when the first DC driving voltage is less than the threshold voltage, the first capacitor is turned off in parallel with the second capacitor, and the second capacitor is controlled according to the second capacitor.

In one embodiment, the switching component is further connected to the second capacitor, and the other component is coupled to the second capacitor. When the first DC driving voltage is greater than the threshold voltage, the switching component is turned on. The first capacitor is connected in parallel with the second capacitor, and when the first DC driving voltage is less than the threshold voltage value, the switching element is turned off.

In an embodiment, the method further includes a first capacitor and a second capacitor. When the first DC driving voltage is greater than the threshold voltage, the connection between the first capacitor and the second capacitor is cut off, according to the first The capacitor provides the first capacitance value to control the conduction time, and when the first DC driving voltage is less than the threshold voltage value, the first capacitor is connected in series with the second capacitor to provide the second capacitance value to control the conduction time.

In one embodiment, the device further includes a switching component, wherein one end of the switching component is grounded, and the other end is coupled to the common junction of the first capacitor and the second capacitor, when the first DC driving voltage is greater than the threshold voltage When the value is up, the switching element is turned on, so that the first capacitor is grounded, and when the first DC driving voltage is less than the threshold voltage value, the switching element is turned off, so that the first capacitor is connected in series with the second capacitor.

In an embodiment, the power factor control unit generates a pulse width modulation signal switching switch to control the voltage conversion unit, and converts the first DC driving voltage into the second DC driving according to the conduction time. Voltage.

In an embodiment, a switching component is further coupled to the power factor control unit, wherein when the first DC driving voltage is lower than a predetermined voltage, the power supply to the power factor control unit is terminated.

In an embodiment, the light emitting unit is a light emitting diode unit.

In an embodiment, the voltage conversion unit is a flyback converter.

According to another aspect of the present invention, a method for dynamically adjusting a dimming range is provided, which at least includes: modulating an AC voltage and rectifying the modulated AC voltage into a first DC driving voltage; Time converting the first DC driving voltage into a second DC driving voltage, wherein when the first DC driving voltage is greater than a threshold voltage value, controlling the conduction time according to a first capacitance value, and when the first direct When the flow driving voltage is less than the threshold voltage value, the conduction time is controlled according to a second capacitance value, wherein the second capacitance value is smaller than the first capacitance value; and the second DC driving voltage is used to drive a light emitting unit to emit light.

In an embodiment, the method further includes: when the first DC driving voltage is greater than the threshold voltage, paralleling a first capacitor and a second capacitor to provide the first capacitor value to control the on time, and when the first When the DC driving voltage is less than the threshold voltage, the first capacitor is connected in parallel with the second capacitor, and the second capacitor value is controlled according to the second capacitor value.

In an embodiment, the method further includes providing a switching component, wherein one end of the switching component is grounded, and the other end is coupled to the second capacitor, and when the first DC driving voltage is greater than the threshold voltage, the switching component is controlled to be turned on. The first capacitor is connected in parallel with the second capacitor, and when the first DC driving voltage is less than the threshold voltage, the switching element is controlled to be turned off.

In an embodiment, the method further includes: when the first DC driving voltage is less than the threshold voltage, controlling a first capacitor in series with a second capacitor to provide the second capacitor value to control the on time, and when the first When a DC driving voltage is greater than the threshold voltage, the connection between the first capacitor and the second capacitor is cut off, and the conduction time is controlled according to the first capacitor value provided by the first capacitor.

In an embodiment, the method further includes providing a switching component, wherein one end of the switching component is grounded, and the other end is coupled to a common junction of the first capacitor and the second capacitor, when the first DC driving voltage is greater than the threshold When the voltage value is controlled, the switching element is controlled to be turned on, so that the first capacitor is grounded, and when the first DC driving voltage is less than the threshold voltage value, the switching element is controlled to be turned off, so that the first capacitor is connected in series with the second capacitor .

In an embodiment, the method further includes generating a pulse width modulation signal switching switch to control the conduction time to convert the first DC driving voltage into the second DC driving voltage.

In an embodiment, the method further includes: stopping generating the pulse width modulation signal when the first DC driving voltage is lower than a predetermined voltage.

In an embodiment, the light emitting unit is a light emitting diode.

In one embodiment, the first DC drive voltage is converted to a second DC drive voltage using a flyback converter.

The invention adjusts the on-time of the switching power supply power switch by dynamically adjusting the timing capacitance value of the power factor control unit, so that the dimmer is not limited by the fixed capacitance value of the power factor control unit when performing brightness adjustment. It is possible to expand the overall dimming range. In addition, the present invention can interrupt the supply of power to the light-emitting unit to prevent the occurrence of flickering when the brightness is adjusted to a minimum straightness, and the power supply of the power factor control unit is turned off.

The following description of the preferred embodiments of the invention is in the

Fig. 1 is a schematic view showing a light-emitting diode driving device capable of dynamically adjusting a dimming range according to an embodiment of the present invention. The LED driving device 100 of the present invention comprises: a dimming unit 101, a voltage converting unit 102, a lighting unit 103, a feedback unit 104, a power factor control unit 105, a switching element SW, and a first The switching element SW1, a second switching element SW2, a timing capacitor C1, and an extended timing capacitor C2. The external AC power source AC is adjusted by the dimming unit 101 to adjust the phase of the voltage signal and rectified into a first DC driving voltage VCC1, wherein the first DC driving voltage VCC1 is supplied to the voltage converting unit 102. The power factor control unit 105 controls the switching frequency and the duty cycle of a switching element SW, and is converted into a second DC driving voltage VCC2 by the voltage converting unit 102, and is supplied to the light emitting unit 103 to drive the light emitting unit 103 to emit light. The feedback unit 104 detects the second DC driving voltage VCC2 and supplies the change signal to the power factor control unit 105. The power factor control unit 105 adjusts the adjustment signal according to the change signal of the second DC driving voltage VCC2. The switching element SW switches the frequency and the duty cycle such that the second DC driving voltage VCC2 is maintained at a predetermined value. The first switching element SW1 is configured to control one end of the extended timing capacitor C2 to be grounded. When the first switching element SW1 is turned on, the extended timing capacitor C2 and the timing capacitor C1 form a parallel structure, so that the timing connected to the power factor control unit 105 is connected. The capacitor is changed from the original timing capacitor C1 to the parallel extended timing capacitor C2 and the timing capacitor C1.

The second switching element SW2 is configured to provide power to the power factor control unit 105. When the second switching element SW2 disconnects the power factor control unit 105 from a power source, the power factor control unit 105 stops operating and no longer drives the switching element. SW, so that the voltage conversion unit 102 also stops operating, no longer supplies the two DC driving voltages VCC2 to the light emitting unit 103, and thus the light emitting unit 103 stops emitting light. In an embodiment, for example, a cutoff voltage value can be set. When the dimming unit 101 performs brightness adjustment, the first DC driving voltage VCC1 output by the dimming unit 101 is changed. The driving voltage VCC1 is compared with the set cutoff voltage value. Once less than the cutoff voltage value, the control switching element SW2 is turned off, and the driving power supply connection of the power factor control unit 105 is turned off. On the other hand, if the first DC driving voltage VCC1 is greater than the OFF voltage value, the control switching element SW2 is turned on, and the power factor control unit 105 is kept connected to the driving power source.

2 is a circuit diagram of a light-emitting diode driving device capable of dynamically adjusting a dimming range according to an embodiment of the invention. The dimming unit 101 further includes a dimmer 1011, an electromagnetic interference (EMI) 1012, and a rectifier 1013. The electromagnetic interference filter 1012 is connected between the AC voltage source AC and the rectifier 1013 to eliminate the AC. Electromagnetic interference in the voltage source AC. That is, the electromagnetic interference filter 1012 eliminates pulse noise, harmonics, and the like. The rectifier 1013 is, for example, a bridge rectifier that receives an AC voltage from an AC voltage source AC and rectifies the AC voltage into a first DC drive voltage VCC1.

The voltage conversion unit 102, in a preferred embodiment, is a flyback converter 1021. The flyback converter 1021 is connected to the rectifier 1013, receives the first DC drive voltage VCC1, and converts it into a second DC drive voltage VCC2 for output to the light emitting unit 103. The light-emitting unit 103 is, for example, a plurality of light-emitting diodes connected in series or a plurality of light-emitting diodes connected in parallel. The flyback converter 1021 includes a primary side winding N1, a secondary side winding N2, a diode Do, and an output capacitor Co. The switching element SW controls the operation of the flyback converter 1021. When the switching element SW is turned on, the current generated by the first DC driving voltage VCC1 flows through the primary winding N1 of the transformer, and since the polarity of the secondary winding N2 and the primary winding N1 are opposite, the diode Do Will be reverse biased, so no energy is transferred to the load, at which point the energy will be stored in the transformer, and the output will continue to provide energy from the output capacitor Co. When the switching element SW is turned off, the primary side winding N1 is open, the primary side current drop is zero, and the magnetic flux density in the transformer will change in the negative direction, so the voltage on all the windings will be reversed and the diode Do Turning on, and the magnetizing current will be transferred to the secondary side to become the second DC driving voltage VCC2, that is, the energy stored in the transformer will be transmitted to the output capacitor Co and the light emitting unit 103 via the diode Do, so that the light emitting unit 103 light.

The feedback unit 104 is configured to provide the output voltage and current signals of the light-emitting unit 103 to the power factor control unit 105, thereby adjusting the output pulse width modulation (PWM) signal. The feedback unit 104 includes at least a voltage error amplifier and a current error amplifier. The power factor control unit 105 adjusts the switching frequency of the switching element SW according to the voltage error and the current error signal fed back by the feedback unit 104, so that the switching frequency of the switching element SW is transmitted to the transformer once. The duty ratio of the first DC driving voltage VCC1 of the side winding N1 is changed, and the power of the input primary winding N1 is adjusted to maintain the second DC driving voltage VCC2 at a predetermined value.

The power factor control unit 105 is configured to generate a Pulse Width Modulation (PWM) signal to control the switching frequency of the switching element SW, thereby achieving the purpose of shaping the waveform of the first DC driving voltage VCC1, and the pulse width The modulation signal control switching element SW cuts the first DC driving voltage VCC1 into a series of voltage pulse waves, and then outputs it to the light-emitting unit 103 by using the voltage conversion unit 102 to convert it into a smooth second DC driving voltage VCC2.

As shown in Fig. 3, a schematic diagram of a pulse width modulation signal is generated by the power factor control unit 105. It should be noted that only one comparator 301 is drawn in the power factor control unit 105, and other components are not drawn. The switching element SW is controlled by the comparison result of the VS voltage and the VC voltage of the pulse width modulation comparator 301. When the VS voltage is greater than the VC voltage, the comparator output is high, and when the VS voltage is less than the VC voltage, the comparator output is Is low. The VC voltage is a voltage generated when a voltage source VDD charges the extended timing capacitor C2 and the timing capacitor C1. In one embodiment, if the switching element SW is an NMOS transistor, when the circuit starts operating, when the VS voltage is greater than the VC voltage, the comparator output is high, the switching element SW is turned on, and the first DC driving voltage VCC1 is transmitted to The voltage conversion unit 102 converts it into a smooth second DC driving voltage VCC2 and outputs it to the light emitting unit 103. The voltage source VDD starts to charge the timing capacitor C1, and the VC voltage gradually rises. When the VC voltage is greater than the VS voltage, the comparator output is low and the switching element SW is turned off.

Therefore, the switching frequency and the on-time of the switching element SW are related to the capacitance value of the timing capacitor C1. If the capacitance value of the timing capacitor C1 is large, the time required for the voltage source VDD to charge the timing capacitor C1 to be greater than the VS voltage is longer, so the switching element SW is turned on for a longer time. On the other hand, if the capacitance value of the timing capacitor C1 is small, the time required for the voltage source VDD to charge the timing capacitor C1 to be greater than the VS voltage is shorter, so the switching element SW has a shorter on-time. Since the capacitance value of the conventional timing capacitor C1 is fixed. In other words, once the small capacitance value of the timing capacitor C1 is used, when the dimming is performed, when the first DC driving voltage VCC1 is to be increased to increase the brightness of the light emitting unit 103, the timing capacitor C1 with a small capacitance value is used. The time required for the timing capacitor C1 to be charged to be greater than the VS voltage is shortened, resulting in a limitation of the switching element SW duty cycle, such that the power transmitted to the second DC driving voltage VCC2 is limited, causing the luminance of the light-emitting unit 103 not to be equalized. . On the other hand, when the timing capacitor C1 with a large capacitance value is used, when the dimming is performed to lower the luminance of the light-emitting unit 103 when the first DC driving voltage VCC1 is to be lowered, the timing capacitor C1 having a large capacitance value is used. The on-time and duty cycle of the switching element SW are greatly increased, so that the luminance of the light-emitting unit 103 is not equally reduced.

In other words, the timing capacitor C1 with a fixed capacitance value has a certain dimming range when dimming is performed. Therefore, as shown in FIG. 3, the timing capacitor C1 is connected in parallel to expand the timing capacitor C2 to expand the capacitance value. At the same time, a first switching element SW1 is used to control whether the extended timing capacitor C2 is connected in parallel with the timing capacitor C1, wherein one end of the first switching element SW1 is grounded, the other end is coupled to the extended timing capacitor C2, and a control signal controls the first switching element. Switching of SW1. When the dimming unit 101 adjusts the direction of increasing the brightness, the capacitance value can be increased by switching the first switching element SW1 to connect the extended timing capacitor C2 in parallel with the timing capacitor C1. On the other hand, when the dimming unit 101 adjusts the direction of decreasing the brightness, the capacitance value can be lowered by switching the connection between the extended timing capacitor C2 and the timing capacitor C1 by switching the first switching element SW1. In other words, in this embodiment, by extending the extended timing capacitor C2 and the timing capacitor C1 in parallel, the original small capacitance value is increased to expand the entire dimming range. Therefore, in this embodiment, the original timing capacitor C1 has a small capacitance value. In addition, when the switching of the first switching element SW1 is controlled, a switching threshold voltage value can be set. When the dimming unit 101 performs brightness adjustment, the first DC driving voltage VCC1 output by the dimming unit 101 is changed. The first DC driving voltage VCC1 is compared with the set switching threshold voltage value. Once greater than the switching threshold voltage value, the first switching element SW1 is controlled to be turned on, and the extended timing capacitor C2 is connected in parallel with the timing capacitor C1 to increase the capacitance value. On the other hand, if the first DC driving voltage VCC1 is less than the switching threshold voltage value, the first switching element SW1 is controlled to be turned off, and the connection between the extended timing capacitor C2 and the timing capacitor C1 is cut off to lower the overall capacitance value.

Fig. 4 is a view showing a circuit structure which can expand the dimming range according to another embodiment of the present invention. Similarly, only one comparator 301 is drawn in the power factor control unit 105, and other components are not drawn. A first switching element SW1 controls whether the extended timing capacitor C2 is connected in series with the timing capacitor C1, wherein one end of the first switching element SW1 is grounded, and the other end is coupled to a common connection point of the extended timing capacitor C2 and the timing capacitor C1, a control signal The switching of the first switching element SW1 is controlled. When the dimming unit 101 adjusts in the direction of increasing the brightness, the timing capacitor C1 can be grounded by turning on the first switching element SW1. On the contrary, when the dimming unit 101 adjusts the direction of decreasing the brightness, the expansion timing capacitor C2 and the timing capacitor C1 can be connected in series to cut the capacitance value by turning off the first switching element SW1. In other words, in this embodiment, the entire dimming range is adjusted by causing the extended timing capacitor C2 to be in series with the timing capacitor C1 to lower the original large capacitance value. Therefore, in this embodiment, the original timing capacitor C1 has a large capacitance value. Similarly, in this embodiment, a switching threshold voltage value may also be set, and when the first DC driving voltage VCC1 outputted by the dimming unit 101 changes, the switching threshold of the first DC driving voltage VCC1 and the setting is set at this time. The voltage values are compared. Once greater than the switching threshold voltage value, the first switching element SW1 is controlled to be turned on, and the timing capacitor C1 is grounded to increase the capacitance value. On the other hand, if the first DC driving voltage VCC1 is less than the switching threshold voltage value, the first switching element SW1 is controlled to be turned off, and the connection between the extended timing capacitor C2 and the timing capacitor C1 is cut off to lower the overall capacitance value.

Figure 5 is a flow chart showing the dynamic adjustment of the dimming range in accordance with an embodiment of the present invention, see Figures 2 and 5. First, in step 501, an AC mains is adjusted and rectified into a first DC driving voltage. In one implementation, a dimmer 1011 adjusts an AC mains to reduce or increase the current output to the lighting unit 103. The adjusted AC mains is rectified to a first stage via a rectifier 1013, such as a bridge rectifier. A DC drive voltage VCC1. In step 502, the first DC driving voltage VCC1 is compared with the set switching threshold voltage value, and in step 502, it is determined whether the first DC driving voltage VCC1 is greater than a set switching threshold voltage value.

If the first DC driving voltage VCC1 is greater than the set switching threshold voltage value, in step 504, the capacitance value is increased to increase the conduction time of the switching element SW. In an embodiment, when the dimming unit 101 is in the direction of increasing the brightness. During the adjustment, the first DC driving voltage VCC1 is made larger than the set switching threshold voltage, and the capacitance value can be increased by switching the first switching element SW1 to connect the extended timing capacitor C2 in parallel with the timing capacitor C1 as shown in FIG. Or in another embodiment, as shown in FIG. 4, the original series-connected extended timing capacitor C2 is disconnected from the timing capacitor C1 to expand the entire capacitance value. On the other hand, if the first DC driving voltage VCC1 is less than the set switching threshold voltage value, in step 505, the capacitance value is decreased to reduce the conduction time of the switching element SW. In an embodiment, when the dimming unit 101 is in the direction of decreasing the brightness. When the adjustment is made, the capacitance value can be lowered by switching the connection between the extended timing capacitor C2 and the timing capacitor C1 by switching the first switching element SW1. Or in another embodiment, as shown in FIG. 4, the timing capacitor C1 is connected in series with the extended timing capacitor C2 to reduce the entire capacitance value. Next, in step 506, a pulse width modulation (PWM) signal is adjusted according to the adjusted capacitance value. In step 507, the first DC driving voltage VCC1 is converted into a second DC driving voltage VCC2 according to the pulse width modulation signal to drive a light emitting unit 103.

Figure 6 is a flow chart showing the dynamic adjustment of the dimming range in accordance with another embodiment of the present invention, see Figures 2 and 6. First, in step 501, an AC mains is adjusted and rectified into a first DC driving voltage. In one embodiment, a dimmer 1011 adjusts an AC mains to reduce or increase the current output to the lighting unit 103. The adjusted AC mains is rectified into a whole via a rectifier 1013, such as a bridge rectifier. The first DC drive voltage VCC1. Next, in step 601, the first DC driving voltage VCC1 is compared with the set OFF voltage value, and in step 602, it is determined whether the first DC driving voltage VCC1 is greater than the OFF voltage value. If the first DC driving voltage VCC1 is less than the OFF voltage value, then step 603 is performed to disconnect the power factor control unit 105 from a power source. On the other hand, if the first DC driving voltage VCC1 is greater than the cutoff voltage value, step 502 is performed, and the first DC driving voltage VCC1 is compared with the set switching threshold voltage value, and in step 502, the first DC driving is performed. The voltage VCC1 is compared with the set switching threshold voltage value, and in step 502, it is determined whether the first DC driving voltage VCC1 is greater than a set switching threshold voltage value.

If the first DC driving voltage VCC1 is greater than the set switching threshold voltage value, in step 504, the capacitance value is increased to increase the conduction time of the switching element SW. In an embodiment, when the dimming unit 101 is in the direction of increasing the brightness. During the adjustment, the first DC driving voltage VCC1 is made larger than the set switching threshold voltage, and the capacitance value can be increased by switching the first switching element SW1 to connect the extended timing capacitor C2 in parallel with the timing capacitor C1 as shown in FIG. Or in another embodiment, as shown in FIG. 4, the original series-connected extended timing capacitor C2 is disconnected from the timing capacitor C1 to expand the entire capacitance value. On the other hand, if the first DC driving voltage VCC1 is less than the set switching threshold voltage value, in step 505, the capacitance value is decreased to reduce the conduction time of the switching element SW. In an embodiment, when the dimming unit 101 is in the direction of decreasing the brightness. When the adjustment is made, the capacitance value can be lowered by switching the connection between the extended timing capacitor C2 and the timing capacitor C1 by switching the first switching element SW1. Or in another embodiment, as shown in FIG. 4, the timing capacitor C1 is connected in series with the extended timing capacitor C2 to reduce the entire capacitance value. Next, in step 506, a pulse width modulation (PWM) signal is adjusted according to the adjusted capacitance value. In step 507, the first DC driving voltage VCC1 is converted into a second DC driving voltage VCC2 according to the pulse width modulation signal to drive a light emitting unit 103.

In summary, the present invention adjusts the switching time of the power switch (switching element SW) of the switching power supply by dynamically adjusting the capacitance value of the power factor control unit, so that the dimmer is not affected by the brightness adjustment. Due to the limitation of the fixed capacitance value of the control unit, the overall dimming range can be expanded. In addition, the present invention can interrupt the supply of power to the light-emitting unit when the brightness is adjusted to a minimum value to cut off the power supply of the power control unit to prevent the occurrence of flickering.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

100. . . Light-emitting diode driving device

101. . . Dimming unit

102. . . Voltage conversion unit

103. . . Light unit

104. . . Feedback unit

105. . . Power factor control unit

1011. . . Light modulator

1012. . . Electromagnetic interference filter

1013. . . Rectifier

1021. . . Flyback converter

301. . . Comparators

SW. . . Switching element

SW1. . . First switching element

SW2. . . Second switching element

C1. . . Timing capacitor

C2. . . Extended timing capacitor

AC. . . AC power

VCC1. . . First DC drive voltage

VCC2. . . Second DC drive voltage

N1. . . Primary winding

N2. . . Secondary winding

Do. . . Dipole

Co. . . Output capacitor

501~507. . . step

601~603. . . step

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

Fig. 1 is a schematic view showing a driving device capable of dynamically adjusting a dimming range according to an embodiment of the present invention.

2 is a circuit diagram of a driving device capable of dynamically adjusting a dimming range according to an embodiment of the present invention.

Fig. 3 is a diagram showing the circuit structure which can expand the dimming range according to an embodiment of the present invention.

Fig. 4 is a view showing a circuit structure which can expand the dimming range according to another embodiment of the present invention.

Figure 5 is a flow chart showing the dynamic adjustment of the dimming range in accordance with an embodiment of the present invention.

Figure 6 is a flow chart showing the dynamic adjustment of the dimming range in accordance with another embodiment of the present invention.

100. . . Light-emitting diode driving device

101. . . Dimming unit

102. . . Voltage conversion unit

103. . . Light unit

104. . . Feedback unit

105. . . Power factor control unit

SW. . . Switching element

SW1. . . First switching element

SW2. . . Second switching element

C1. . . Timing capacitor

C2. . . Extended timing capacitor

AC. . . AC power

VCC1. . . First DC drive voltage

VCC2. . . Second DC drive voltage

Claims (8)

The driving device capable of dynamically adjusting the dimming range comprises at least: a dimming unit for modulating an alternating voltage and rectifying the modulated alternating current voltage into a first direct current driving voltage; and a voltage converting unit according to The first DC driving voltage is converted into a second DC driving voltage by an on-time; a light-emitting unit corresponding to the light generated according to the second DC driving voltage; and a power factor control unit for controlling the conduction time When the first DC driving voltage is greater than a threshold voltage value, the power factor control unit controls the conduction time according to a first capacitance value, and when the first DC driving voltage is less than the threshold voltage value, The power factor control unit controls the conduction time according to a second capacitance value, wherein the second capacitance value is smaller than the first capacitance value; and a first capacitor, a second capacitor, and a switching component, wherein one end of the switching component is grounded The other end is coupled to the second capacitor. When the first DC driving voltage is greater than the threshold voltage, the switching component is turned on, so that the first capacitor The second capacitor is connected in parallel to provide the first capacitor value to control the on-time, and when the first DC driving voltage is less than the threshold voltage, the switching component turns off the parallel connection between the first capacitor and the second capacitor. The on-time is controlled according to the second capacitance value provided by the first capacitor. The driving device of claim 1, further comprising a feedback unit, wherein the lighting result of the lighting unit is returned to the power factor control unit for control The conduction time. The driving device of claim 1, wherein the power factor control unit generates a pulse width modulation signal switching switch to control the voltage conversion unit, and converts the first DC driving voltage into the current according to the conduction time. The second DC drive voltage. The driving device of claim 1, further comprising a switching component coupled to the power factor control unit, wherein when the first DC driving voltage is lower than a predetermined voltage, terminating providing a power source to the power factor control unit . The driving device of claim 1, wherein the light emitting unit is a light emitting diode unit. The driving device of claim 1, wherein the voltage converting unit is a flyback converter. A method for dynamically adjusting a dimming range includes: modulating an alternating current voltage and rectifying the modulated alternating current voltage into a first direct current driving voltage; converting the first direct current driving voltage into a first according to an on time a DC driving voltage, wherein when the first DC driving voltage is greater than a threshold voltage value, the conduction time is controlled according to a first capacitance value, and when the first DC driving voltage is less than the threshold voltage value, according to Second capacitance value Controlling the on-time, wherein the second capacitance value is less than the first capacitance value; and driving the illumination unit to emit light using the second DC drive voltage, wherein when the first DC drive voltage is greater than the threshold voltage value, parallel a first capacitor and a second capacitor to provide the first capacitor value to control the on-time, and when the first DC driving voltage is less than the threshold voltage, the first capacitor is connected in parallel with the second capacitor, according to the The second capacitance value provided by the first capacitor controls the conduction time. The method of claim 7, further comprising: generating a pulse width modulation signal switching switch to control the conduction time to convert the first DC driving voltage to the second DC driving voltage.