CN104936329B - Device for driving light emitting diode using high voltage - Google Patents

Abstract

A device for driving a plurality of light emitting diodes using a high voltage comprises a plurality of light emitting diodes divided into a plurality of light emitting diode segments connected in series, and a switching voltage detector and a current limiter connected in series therewith. Each light emitting diode segment is connected in parallel with a switch, and a high input voltage supplies power to the entire light emitting diode device. When the input voltage rises, the switching voltage detector generates a first mode change signal, and when the input voltage drops, a second mode change signal is generated. A controller receives the two mode change signals and generates a plurality of control signals to control each switch individually to change the operation mode of the light emitting diode device.

Description

Devices for driving light-emitting diodes using high voltage

technical field

The present invention relates to light emitting diode (LED) based lighting devices, in particular a driving device for a LED based lighting device using high voltage.

Background technique

Light-emitting diode (LED) is a semiconductor-based light source, which was often used in low-power consumption meters and indicators of home appliances in the past. Due to the advancement of technology to improve brightness, the application of light-emitting diodes in various lighting devices has become more and more common. . For example, high-brightness light-emitting diodes have been widely used in traffic lights, vehicle lights, and brake lights. In recent years, lighting fixtures using strings of high-voltage LEDs have also been developed to replace traditional incandescent and fluorescent bulbs.

The current-to-voltage (IV) characteristic curve of a light-emitting diode is similar to a general ordinary diode. When the voltage applied to the light-emitting diode is less than the forward voltage of the diode, only a very small current flows through the light-emitting diode. When the voltage exceeds the forward voltage, the current through the LED increases significantly. In general, the luminous intensity of an LED-based lighting device is proportional to the current passing through most of the operating range, but not when operating at high currents. Generally, the driving device designed for LED-based lighting devices is mainly to provide a constant current so as to emit stable light and prolong the life of the LED.

In order to improve the brightness of LED-based lighting devices, a plurality of LED-based lighting units are usually connected in series to form a LED-based lighting unit, and a plurality of LED-based lighting units can be further connected in series to form a lighting unit. device. The working voltage required for each lighting device usually depends on the forward voltage of the light-emitting diodes in the lighting unit, how many light-emitting diodes are in each lighting unit, how each lighting unit is connected to each other, and the How a lighting unit receives voltage from a power source in a lighting fixture.

Therefore, in most applications, some type of power voltage conversion device is required to convert the generally more common high voltage power supply to a lower voltage for supplying one or more LED-based lighting units . Because of the need for such a voltage conversion device, the efficiency of the lighting equipment based on the light-emitting diode is reduced, the cost is increased, and it is difficult to reduce its volume.

In order to improve the efficiency and reduce the size of the LED-based lighting device, many technologies have been developed so that the LED-based lighting device can use AC power such as 120V or 240V without a voltage conversion device. Generally, the LEDs in LED-based lighting devices are divided into a plurality of LED segments. Each LED segment can be selectively turned on and off as the AC voltage increases or decreases under the control of an associated switch or current source. All switches or current sources in the lighting device are controlled by a controller.

In the previous technology, most of the high-voltage LED-based lighting devices used to detect the voltage value of the input AC power supply or the current value flowing through the lighting device to control the switch or current source to select To switch LED segments on and off. For example, US Patent Nos. 6,989,807 and 8,324,840, and US Patent Publication No. 2011/0089844 all have an integral controller capable of detecting the voltage value of an input voltage to control a switch or a current source connected to a light emitting diode. US Patent Publications No. 2012/0056559 and No. 2012/0217887 use an integral controller to control the current limiter or switch according to the detected local current.

Since more and more light-emitting diode-based lighting units have been applied to high-brightness lighting equipment using high voltage, how to use the existing AC power on the wall to flexibly and effectively increase the utilization rate of light-emitting diodes, Design methods and apparatus for driving and connecting multiple LED-based lighting units that reduce power consumption and provide stability and high brightness have formed an indispensable need.

Contents of the invention

The invention is made to provide a device capable of using high voltage and efficiently driving light-emitting diode strings. According to the device provided by the present invention, a plurality of light emitting diodes are divided into a plurality of LED segments connected in series, and connected in series with a switching voltage detector and a current limiter.

Each light-emitting diode segment is connected in parallel with a switch, and there is a switch controller in the device that outputs binary code or non-binary code to turn on or off each parallel switch, so that the lighting device based on light-emitting diodes, Its operation mode can be changed as the voltage value of the input voltage changes.

In the first preferred embodiment of the present invention, the switching voltage detector is connected to the last LED segment, and the current limiter is connected between the switching voltage detector and the ground. The switching voltage detector includes a dropout detector for detecting the change of the input voltage, and a mode change signal generator for generating a mode change signal when the input voltage changes.

In the first preferred embodiment, the differential pressure detector includes three N-type voltage-controlled current limiters, and each N-type voltage-controlled current limiter has three terminals. In a first embodiment of the differential pressure detector, one or more light emitting diodes are connected between the first terminals of the first and second voltage controlled current limiters. One or more light emitting diodes are also connected between the first terminals of the second and third voltage-controlled current limiters.

The second terminal of each N-type voltage-controlled current limiter is connected to a bias voltage, and the third terminal is connected to a common node through a current sensor. The mode change signal generator has two comparators connected to the three current sensors, and a control signal generator receives the outputs of the two comparators and generates two mode change signals according to the change of the input voltage.

In the second type of fabrication of the differential pressure detector, the first terminal of each N-type voltage-controlled current limiter is connected to one terminal of a respective current sensor, and each two adjacent current sensors One or more LEDs are connected between the other ends of the device. The second terminal of each N-type voltage-controlled current limiter is connected to a bias voltage, and the third terminal is connected to a common node.

There are three differential amplifiers respectively connected to the two ends of the three current sensors, the mode change signal generator has two comparators connected to the outputs of the three differential amplifiers, and a control signal generator receives the output of the two comparators output, and generates two mode change signals based on changes in the input voltage.

In a second preferred embodiment of the present invention, the switching voltage detector is connected to the leading LED segment, and the current limiter is connected between the input voltage and the switching voltage detector. The switching voltage detector includes a dropout detector for detecting the change of the input voltage, and a mode change signal generator for generating a mode change signal when the input voltage changes.

In the second preferred embodiment, the differential pressure detector includes three P-type voltage-controlled current limiters, and each P-type voltage-controlled current limiter has three terminals. In the first embodiment of the differential pressure detector, one or more light emitting diodes are connected between the first terminals of the first and second voltage controlled current limiters. One or more light-emitting diodes are also connected between the first terminals of the second and third voltage-controlled current limiters.

Each P-type voltage-controlled current limiter has a voltage source connected between its second terminal and the input voltage, and its third terminal is connected to a common node through a current sensor. The mode change signal generator has two comparators connected to the three current sensors, and a control signal generator receives the outputs of the two comparators and generates two mode change signals according to the change of the input voltage.

In the second type of fabrication example of the dropout voltage detector, the third terminal of each P-type voltage-controlled current limiter is directly connected to a common node, and the second terminal is connected to the input voltage via a voltage source, the first The terminals are connected to one end of each current sensor, and one or more LEDs are connected between the other ends of each two adjacent current sensors.

Similar to the second-type production example of the differential pressure detector in the first preferred embodiment, the second-type production example of the differential pressure detector in the second preferred embodiment also has three differential amplifiers respectively connected to three across the current sensor. The mode change signal generator has two comparators connected to the outputs of the three differential amplifiers, and a control signal generator receives the outputs of the two comparators and generates two mode change signals according to the change of the input voltage.

Description of drawings

1 is a block diagram showing an apparatus for driving LED strings with a high voltage according to a first preferred embodiment of the present invention;

FIG. 2 shows the voltage value V _IN of the input voltage of the light-emitting diode-based lighting device of the present invention, using rectified AC power, operating in M different lighting modes;

FIG. 3 shows an example of a switch controller including a ripple counter to generate binary code;

FIG. 4 shows another example of a switch controller including a ripple counter for generating binary code and a memory for converting the binary code into non-binary code;

FIG. 5(A) is a block diagram showing a first type fabrication example of the switching voltage detector in the first preferred embodiment of the present invention;

FIG. 5(B) is a block diagram showing a second type of manufacturing example of the switching voltage detector in the first preferred embodiment of the present invention;

Fig. 6 shows the characteristics of the current to voltage (I-V) of the voltage-controlled current limiter used to switch the three terminals of the N-type voltage detector in the first preferred embodiment;

Fig. 7 shows the signal waveforms of several signals in the mode change signal generator in the first preferred embodiment;

8 is a block diagram showing a device for driving LED strings with high voltage according to a second preferred embodiment of the present invention;

FIG. 9(A) is a block diagram showing a first-type manufacturing example of a switching voltage detector according to a second preferred embodiment of the present invention;

FIG. 9(B) is a block diagram showing a second fabrication example of the switching voltage detector of the second preferred embodiment of the present invention;

Fig. 10 shows the characteristics of the current to voltage (I-V) of the voltage-controlled current limiter used to switch the three terminals of the P-type in the differential pressure detector in the voltage detector in the second preferred embodiment;

FIG. 11 shows signal waveforms of several signals in the mode change signal generator in the second preferred embodiment.

Wherein, the reference signs are explained as follows:

100, 800 LED segments

110, 810 switch

120, 820 switch controller

130, 830 switching voltage detector

140, 840 current limiter

141, 841 resistance

301 Ripple Counter

302 switch driver

401 storage element

501, 501', 901, 901' differential pressure detector

502, 902 mode change signal generator

511, 512, 513, 911, 912, 913 current sensors

521, 523, 921, 923 Bias Voltage Switcher

531, 533, 931, 933 winding switch

541, 542, 941, 942 comparators

551, 552, 553, 951, 952, 953 current sensors

561, 562, 563, 961, 962, 963 differential amplifier

detailed description

This specification provides accompanying drawings, so that the present invention can be further understood, and the accompanying drawings also constitute a part of this specification. The drawings illustrate the embodiments of the invention and, together with the description, serve to explain the principles of the invention.

1 is a block diagram showing a device for driving light-emitting diode strings with a high voltage according to a first preferred embodiment of the present invention. The device of this embodiment includes a plurality of light-emitting diodes connected in series and divided into multiple LED segments 100, each LED segment 100 has a positive terminal and a negative terminal, respectively connected to the negative terminal of the preceding LED segment and the positive terminal of the following LED segment.

As shown in FIG. 1 , each LED segment 100 has a switch 110 connected in parallel thereto, and a switch controller 120 supplies a plurality of switching control signals to control the switches 110 . The negative end of a light-emitting diode segment at the end is connected to a switching voltage detector 130, and a current limiter 140 is connected between the switching voltage detector 130 and the ground. The current limiter 140 can also be connected by a resistor 141 to replace.

An input high voltage V _IN is connected to the leading LED segment and switch controller 120 to provide voltage to the entire device to drive all LEDs. The switch voltage detector 130 detects a voltage that varies with the input voltage V _IN to generate two mode change signals UP_P and DN_P to control the switch controller 120 . When the input voltage V _IN rises, the mode change signal UP_P generates a series of mode change pulses to change the state of the switch controller 120 . Similarly, when the input voltage V _IN drops, the mode change signal DN_P generates a series of mode change pulses to change the state of the switch controller 120 .

FIG. 2 shows the voltage values of the input voltage V _IN under M different operation modes for controlling the LED-based lighting device with two mode change signals UP_P and DN_P in the present invention. The input voltage is a rectified AC voltage, and different numbers of LED segments are connected in series in each operation mode. The two mode change signals UP_P and DN_P trigger the switch controller 120 to change state, so that the LED-based lighting device operates in different operation modes.

As shown in FIG. 2 , when the input voltage value V _IN increases from V _i to V _i +1 between times T _i and T _i+1 , the LED-based lighting device operates in mode-i. When the rectified input voltage reaches the maximum value V _IN(MAX) , the voltage starts to decrease. When the input voltage value is between V _M and V _IN(MAX) , the LED-based lighting device operates in mode-M, and when the input voltage value falls between V _i and V _i+1 , the LED-based lighting device operates in mode-M. Operates in mode -i. The difference between the voltage values V _i and V _i+1 is the mode discrimination voltage ΔV.

FIG. 3 shows an example of the switch controller 120 in the first preferred embodiment of the present invention. In this example, the switch controller 120 includes a ripple counter 301 that generates binary codes. The output of the ripple counter 301 is connected to a plurality of switch drivers 302 to drive the plurality of switches 110 shown in FIG. 1 . Therefore, the LED-based lighting device of FIG. 1 can change the operation mode according to the binary code generated by the ripple counter 301 .

FIG. 4 shows another example of the switch controller 120 in the first preferred embodiment of the present invention. As shown in FIG. 4, in this example, a memory element 401 is connected to the output of the ripple counter 301, and the binary code generated by the ripple counter 301 is first converted into a non-binary code, and then connected to a plurality of switch drivers 302 . Therefore, the light-emitting diode-based lighting device of FIG. 1 can use non-binary codes to change the operation mode according to the coded correspondence stored in the storage element 401 .

As shown in FIG. 5(A), the first type of manufacturing example of the switching voltage detector 130 manufactured according to the first preferred embodiment of the present invention includes a voltage difference detector 501 and a mode change signal generator 502 . The differential voltage detector 501 includes three N-type voltage-controlled current limiters M ₁ , M ₂ , and M ₃ , each N-type voltage-controlled current limiter has three terminals. Between the first ends of M1 and _M2 , _one or more LEDs are connected in series. These LEDs can also be replaced by diodes having similar current versus voltage characteristics. Similarly, one or more light-emitting diodes are connected in series between the first ends _{of M2} and M3.

According to the present invention, the N-type voltage-controlled current limiter with three terminals can be manufactured by various semiconductor components. Although Figure 5(A) shows N-channel metal-oxide-semiconductor (NMOS) field-effect transistors, NPN bipolar junction transistors (BJTs) and N-type insulated gate bipolar transistors (IGBTs) are also available. To make an N-type voltage-controlled current limiter.

FIG. 6 shows the current versus voltage (IV) characteristics of an N-type voltage-controlled current limiter with three terminals in the present invention. When the voltage V _bc between the second terminal and the third terminal (terminals b and c) of the current limiter is less than or equal to the threshold voltage V _th of the N-type current limiter, the current limiter is closed, and the current The current I _a through the current limiter is zero.

When the voltage V _bc between the second terminal and the third terminal (terminal b and c) of the current limiter is greater than the threshold voltage V _th of the current limiter, and the first terminal and the third terminal (terminal When the voltage V _ac between a and c) is less than the saturation voltage V _sat of the N-type current limiter, the current limiter acts like a resistor. In other words, the current _Ia flowing through the current limiter is linearly proportional to the voltage _Vac .

It can be seen from Figure 6 that when the voltage V _bc is greater than the threshold voltage V _th of the current limiter, and the voltage V _ac is also greater than the saturation voltage V _sat of the current limiter, the voltage of the N-type three-terminal The controlled current limiter then forms a fixed current source, and the current I _a is a function of the voltage V _bc , that is to say I _a =f(V _bc ). It should be noted that the saturation voltage V _sat of the current limiter is also proportional to the voltage V _bc .

As shown in Figure 5(A), the second terminals of the three N-type voltage-controlled current limiters are respectively connected to three bias voltages V ₁ , V ₂ and V ₃ , when M ₁ , M ₂ and When M ₃ has the same characteristics, the preferred bias voltage should meet the condition of V ₁ <V ₂ <V ₃ . The third terminals of M ₁ , M ₂ and M ₃ are connected to a common node via three respective current sensors 511 , 512 and 513 . It should be noted that the bias voltages V ₁ and V ₃ of M ₁ and M ₃ are controlled by bias voltage switches 521 and 523 , respectively.

In the differential voltage detector 501 , the current sensor is used to determine whether the operation mode of the LED-based lighting device needs to be changed according to the voltage value of the input voltage V _IN . When only _M2 has current passing through, there is no need to switch control, and the operation mode remains unchanged.

When the current flowing through M3 is larger _than that flowing through _M2 , it means that the input voltage V _IN has increased to the point where more LEDs must be connected in series to withstand the higher voltage. Therefore, the mode change signal UP_P of the mode change signal generator 502 must generate a mode change pulse to change the operation mode of the LED-based lighting device. In addition, the mode change signal generator 502 also generates a wait signal to short _- circuit the bypass switch 533, so that no current flows through M3, and only _M2 has a current flow until the required LED segment after the operation mode is changed. have been concatenated.

On the contrary, when the current flowing through M ₁ is larger than that flowing through M ₂ , it means that the input voltage V _IN has been reduced to the point where fewer LEDs must be connected in series. Therefore, the mode change signal DN_P of the mode change signal generator 502 must generate a mode change pulse to change the operation mode of the LED-based lighting device.

The mode change signal generator 502 also generates a wait signal to short-circuit the bypass switch 531 so that no current flows through M ₁ and only M ₂ flows until the required LED segments have been switched off after the operating mode change. in series. It should be noted that the voltage V _com at the common node varies with the input voltage V _IN .

As mentioned above, the bias voltages _V1 and _{V3 of} M1 and _M3 are controlled by the bias voltage switches 521 and 523, respectively. It can be seen from FIG. 5(A) that after the operation mode is changed, the required LED sections have been connected in series, and when the change of the input voltage value must be detected again, the mode change signal generator 502 generates a detection signal, which will Bias voltages V ₁ and V ₃ are connected to M ₁ and M ₃ .

In the mode change signal generator 502, the first comparator 541 has two inputs connected to the current sensors 511 and 512, respectively. The second comparator 542 has two inputs connected to the current sensors 513 and 512 respectively. As shown in FIG. 5(A), the mode change signal generator 502 further includes a signal generator composed of two RS flip-flops, three delay circuits, and several logic gates.

The signal generator in the mode change signal generator 502 receives the outputs of the two comparators to generate a wait signal, a detection signal, and two mode change signals UP_P and DN_P. FIG. 7 shows signal waveforms of several signals in the mode change signal generator 502 . It can be seen from Fig. 5(A) that in the differential pressure detector 501, the _first terminal of M1 is connected to the last LED segment, and the common node V _com is connected to a current limiter in the whole device 140.

According to the first preferred embodiment of the present invention, FIG. 5(B) shows a second-type manufacturing example of the switching voltage detector 130, wherein the differential voltage detector 501' includes three N-type voltage _- controlled current limiters M1 , M ₂ and M ₃ , the first terminals of the three current sensors 551 , 552 and 553 are respectively connected to the first terminals of the three N-type voltage-controlled current limiters M ₁ , M ₂ and M ₃ . Between the second terminals of every two adjacent current sensors, one or more LEDs are connected in series.

Similar to the first type of production example, in the pressure difference detector of the second type of production example, the second terminals of the three N-type voltage-controlled current limiters are respectively connected to the three bias voltages V ₁ , V2 and _V3 , the third terminal of each N _- type voltage controlled current limiter, are directly connected to the common node. There are three differential amplifiers 561 , 562 and 563 respectively connected from the second terminals to the first terminals of the three current sensors 551 , 552 and 553 .

As shown in FIG. 5(B), the first comparator 541 receives the outputs of the differential amplifiers 561 and 562 , and the second comparator 542 receives the outputs of the differential amplifiers 563 and 562 . The mode change signal generator 502 of the second type production example shown in Fig. 5 (B) is the same as the first type production example of Fig. 5 (A), and the operating principle of the differential pressure detector 501' is also similar at the same time, so no longer Repeat instructions.

8 shows a block diagram of an apparatus for driving LED strings with a high voltage according to a second preferred embodiment of the present invention. The apparatus of this embodiment includes a plurality of LEDs connected in series and divided into a plurality of LEDs connected in series. LED segments 800, each LED segment 800 having a positive terminal and a negative terminal, each connected to the negative terminal of the preceding LED segment and the positive terminal of the following LED segment.

As shown in FIG. 8 , each LED segment 800 has a switch 810 connected in parallel thereto, and a switch controller 820 supplies a plurality of switching signals to control the switches 810 . In a second preferred embodiment, the negative terminal of the last LED segment is connected to ground.

An input high voltage V _IN provides voltage to drive all LEDs. A current limiter 840 is connected between the input voltage V _IN and the switching voltage detector 830 for detecting the voltage value of the input voltage V _IN , and generates two mode changing signals UP_P and DN_P to control the switching controller 820 . The current limiter 840 can also be replaced by a resistor 841 .

When the input voltage V _IN rises, the mode change signal UP_P generates a series of mode change pulses to change the state of the switch controller 820 . Similarly, when the input voltage V _IN drops, the mode change signal DN_P generates a series of mode change pulses to change the state of the switch controller 820 .

In the present invention, the switch controller 120 in the first preferred embodiment can also be used as the switch controller 820 in the second preferred embodiment. Similar to the first preferred embodiment, the switch controller 820 can generate binary codes with a ripple counter, or generate non-binary codes with a ripple counter and a code corresponding memory.

As shown in FIG. 9(A), the first type of switching voltage detector 830 manufactured according to the second preferred embodiment of the present invention includes a voltage difference detector 901 and a mode change signal generator 902 . The differential pressure detector 901 includes three P-type voltage-controlled current limiters M ₁ , M ₂ and M ₃ , and each P-type voltage-controlled current limiter has three terminals. Between the first ends of M1 and _M2 , _one or more LEDs are connected in series. Similarly, one or more light-emitting diodes are connected in series between the first ends _{of M2} and M3.

Although Figure 9(A) shows a P-type voltage-controlled current limiter made of a P-channel metal-oxide-semiconductor (PMOS) field-effect transistor, a PNP-type bipolar junction transistor (BJT) and a P-type insulated gate Bipolar transistors (IGBTs) can also be used to make P-type voltage-controlled current limiters.

FIG. 10 shows the current versus voltage (IV) characteristics of a P-type three-terminal voltage-controlled current limiter in the present invention. When the voltage V _cb between the third terminal and the second terminal (terminal c and b) of the current limiter is less than or equal to the threshold voltage V _th of the P-type current limiter, the current limiter is closed, and the current The current I _a through the current limiter is zero.

When the voltage V _cb between the third terminal and the second terminal (terminal c and b) of the current limiter is greater than the threshold voltage V _th of the current limiter, and the third terminal and the first terminal (terminal When the voltage V _ca between c and a) is smaller than the saturation voltage V _sat of the P-type current limiter, the current limiter acts like a resistor. In other words, the current _Ia flowing through the current limiter is linearly proportional to the voltage _Vca .

It can be seen from Figure 10 that when the voltage V _cb is greater than the threshold voltage V _th of the current limiter, and the voltage V _ca is also greater than the saturation voltage V _sat of the current limiter, the P-type voltage with three terminals The controlled current limiter then forms a fixed current source, and the current I _a is a function of the voltage V _cb , that is to say I _a =f(V _cb ). It should be noted that the saturation voltage V _sat of the current limiter is also proportional to the voltage V _cb .

As shown in Fig. 9(A), three voltage sources V ₁ , V ₂ and V ₃ are respectively connected between the input voltage V _IN and the second terminals of the three P-type voltage-controlled current limiters. When M _1. When M ₂ and M ₃ have the same characteristics, a better voltage source should meet the condition of V ₁ <V ₂ <V ₃ . The third terminals of M ₁ , M ₂ and M ₃ are connected to a common node via three respective current sensors 911 , 912 and 913 .

It can be seen from FIG. 9(A) that voltage sources V ₁ and V ₃ are connected to M ₁ and M ₃ through bias voltage switches 921 and 923 respectively. Moreover, in this fabrication, the bias voltages applied to the three PMOSs are respectively the voltage differences between the input voltage V _IN and the voltage sources V ₁ , V ₂ and V ₃ .

Similar to the first preferred embodiment, in the second preferred embodiment, the P-type voltage-controlled current limiters M ₁ and M ₃ with three terminals also have winding switches 931 and 933 connected to the respective second terminals and common nodes.

In the mode change signal generator 902, the first comparator 941 has two inputs connected to the current sensors 912 and 911, respectively. The second comparator 942 has two inputs connected to the current sensors 912 and 913 respectively. As shown in Figure 9 (A), the mode change signal generator 902 includes a signal generator composed of two RS flip-flops, three delay circuits, and several logic gates to generate waiting signals, detect signal, and two mode change signals UP_P and DN_P.

Those who are familiar with the field of the present invention should have understood the working principle of the differential pressure detector 901 in the second preferred embodiment and the mode change signal generator 902 from the above description, and the differential pressure detection in the first preferred embodiment The generator 501 and the mode change signal generator 502 are very similar, so the description will not be repeated here. FIG. 11 shows signal waveforms of several signals in the mode change signal generator 902 .

According to the second preferred embodiment of the present invention, FIG. 9(B) shows a second-type manufacturing example of the switching voltage detector 830, wherein the differential voltage detector 901' includes three P-type voltage _- controlled current limiters M1 , M ₂ and M ₃ , the third terminals of each P-type voltage-controlled current limiter, are directly connected to the common node. Similar to the first type of manufacturing example, three voltage sources V ₁ , V ₂ and V ₃ are respectively connected between the input voltage V _IN and the second terminals of the three P-type voltage-controlled current limiters.

In the second type of production example, the first terminals of the three current inductors 951, 952 and 953 are respectively connected to the first terminals of the _three P-type voltage _- controlled current limiters M1, _M2 and M3 . Between the second terminals of every two adjacent current sensors, one or more LEDs are connected in series. There are three differential amplifiers 961, 962 and 963 respectively connected from the first terminal to the second terminal of the three current sensors 951, 952 and 953.

As shown in FIG. 9(B), the first comparator 941 receives the outputs of the differential amplifiers 961 and 962 , and the second comparator 942 receives the outputs of the differential amplifiers 963 and 962 . The mode change signal generator 902 of the second type production example shown in Fig. 9 (B) is the same as the first type production example of Fig. 9 (A), and the working principle of the differential pressure detector 901' is also similar, so no longer Repeat instructions.

Although the present invention is described above by only a few preferred implementation examples, those who are familiar with the technical field can clearly understand that there are still many undescribed modifications and modifications, all without departing from the present invention defined below within the scope of the patent application.

Claims (20)

1. A device for driving a plurality of light-emitting diodes, comprising: A plurality of LEDs, divided into a plurality of LED segments connected in series, wherein each LED segment has a positive terminal, a negative terminal, and a switch connected in parallel between the positive terminal and the negative terminal; An input voltage, connected to the positive terminal of the most leading LED segment among the plurality of LED segments; A switching voltage detector, having a first end connected to the negative end of the last LED segment among the plurality of LED segments, and generating a first mode change signal when the input voltage rises, and when the input voltage generating a second mode change signal when falling; a current limiter, the first terminal of which is connected to the second terminal of the switching voltage detector, and the second terminal of which is grounded; and a switch controller, receiving the input voltage, the first and second mode change signals, and generating a plurality of switching control signals to respectively control the plurality of LED segments, Wherein, the above-mentioned switching voltage detector further includes a pressure difference detector, and the above-mentioned pressure difference detector includes: A first voltage controlled current limiter having a first terminal, a second terminal connected to the first bias voltage via the first bias voltage switch, and a third terminal connected to a common voltage via the first current sensor node, and a bypass switch connected between the second terminal and the common node; a second voltage-controlled current limiter having a first terminal, a second terminal connected to the second bias voltage, and a third terminal connected to the common node via a second current sensor; A third voltage-controlled current limiter having a first terminal, a second terminal connected to a third bias voltage via a second bias voltage switch, and a third terminal connected to the common node, and a bypass switch connected between the second terminal of the third voltage-controlled current limiter and the common node; one or more light emitting diodes connected in series between the first terminals of said first and second voltage controlled current limiters; and One or more light emitting diodes are connected in series between the first terminals of the second and third voltage controlled current limiters. 2. The device of claim 1, wherein the current limiter is a resistor. 3. The device according to claim 1, wherein the switch controller further comprises: a ripple counter receiving the first and second mode change signals and generating a plurality of counter outputs; and A plurality of switch drivers, receiving the above-mentioned multiple counter outputs, and generating the above-mentioned multiple switching control signals; Wherein, the outputs of the above-mentioned multiple counters are binary codes. 4. The device according to claim 1, wherein the switch controller further comprises: a ripple counter receiving said first and second mode change signals and generating a first plurality of outputs; a storage element receiving said first plurality of outputs and converting said first plurality of outputs into a second plurality of outputs; and A plurality of switch drivers, receiving the above-mentioned second group of multiple outputs, and generating the above-mentioned multiple switching control signals; Wherein, the above-mentioned first plurality of outputs are binary codes, and the second plurality of outputs are non-binary codes. 5. The device according to claim 1, wherein the switching voltage detector further comprises a mode change signal generator, The above mode change signal generator includes: A first comparator having a first input connected to the third terminal of the first voltage-controlled current limiter and having a second input connected to the third terminal of the second voltage-controlled current limiter, and generating a first a comparator output; The second comparator has a first input terminal connected to the third terminal of the above-mentioned third voltage-controlled current limiter, has a second input terminal connected to the third terminal of the above-mentioned second voltage-controlled current limiter, and generates the first two comparator outputs; and A control signal generator, receiving the output of the first and second comparators, and generating the first and second mode change signals; Wherein, the first terminal of the current limiter controlled by the first voltage is connected to the negative terminal of the last LED segment, the common node is connected to the first terminal of the current limiter, and the mode change signal is generated A wait signal is generated to control the two winding switches in the differential pressure detector, and a detection signal is generated to control the two bias voltage switches in the differential pressure detector. 6. The device according to claim 5, wherein the switch controller further comprises: a ripple counter receiving the first and second mode change signals and generating a plurality of counter outputs; and A plurality of switch drivers, receiving the above-mentioned multiple counter outputs, and generating the above-mentioned multiple switching control signals; Wherein, the outputs of the above-mentioned multiple counters are binary codes. 7. The device according to claim 5, wherein the switch controller further comprises: a ripple counter receiving said first and second mode change signals and generating a first plurality of outputs; a storage element receiving said first plurality of outputs and converting said first plurality of outputs into a second plurality of outputs; and A plurality of switch drivers, receiving the above-mentioned second group of multiple outputs, and generating the above-mentioned multiple switching control signals; Wherein, the above-mentioned first plurality of outputs are binary codes, and the second plurality of outputs are non-binary codes. 8. The device according to claim 5, wherein the current limiters controlled by the first, second and third voltages are an N-type MOSFET, an NPN bipolar junction transistor, or N-type insulated gate bipolar transistors. 9. A device for driving a plurality of light emitting diodes, comprising: A plurality of LEDs, divided into a plurality of LED segments connected in series, wherein each LED segment has a positive terminal, a negative terminal, and a switch connected in parallel between the positive terminal and the negative terminal; An input voltage, connected to the positive terminal of the most leading LED segment among the plurality of LED segments; A switching voltage detector, having a first end connected to the negative end of the last LED segment among the plurality of LED segments, and generating a first mode change signal when the input voltage rises, and when the input voltage generating a second mode change signal when falling; a current limiter, the first terminal of which is connected to the second terminal of the switching voltage detector, and the second terminal of which is grounded; and a switch controller, receiving the input voltage, the first and second mode change signals, and generating a plurality of switching control signals to respectively control the plurality of LED segments, Wherein, the above-mentioned switching voltage detector includes a pressure difference detector and a mode change signal generator, wherein the pressure difference detector includes: A first voltage controlled current limiter having a first terminal connected to a first terminal of a first current sensor, a second terminal connected to a first bias voltage via a first bias voltage switch, and a third the terminals are connected to a common node, and a bypass switch is connected between the second terminal and the common node; a second voltage-controlled current limiter having a first terminal connected to the first terminal of the second current sensor, a second terminal connected to the second bias voltage, and a third terminal connected to the common node; A third voltage-controlled current limiter, wherein a first terminal is connected to a first terminal of a third current sensor, a second terminal is connected to a third bias voltage via a second bias voltage switch, and a third terminals connected to said common node, and a wrap switch connected between the second terminal of said third voltage-controlled current limiter and said common node; The first differential amplifier has two input terminals respectively connected to the second terminal and the first terminal of the first current sensor; The second differential amplifier has two input terminals respectively connected to the second terminal and the first terminal of the second current inductor; The third differential amplifier has two input terminals respectively connected to the second terminal and the first terminal of the third current sensor; one or more light emitting diodes connected in series between the second terminals of the first and second current sensors; and one or more light emitting diodes connected in series between the second ends of the second and third current sensors; And the above-mentioned mode change signal generator comprises: The first comparator has a first input terminal connected to the output terminal of the first differential amplifier, a second input terminal connected to the output terminal of the second differential amplifier, and generates a first comparator output; a second comparator having a first input connected to the output of the third differential amplifier, a second input connected to the output of the second differential amplifier, and generating a second comparator output; and A control signal generator, receiving the output of the first and second comparators, and generating the first and second mode change signals; Wherein, the second terminal of the above-mentioned first current sensor is connected to the negative terminal of the last LED section, the above-mentioned common node is connected to the first terminal of the above-mentioned current limiter, and the above-mentioned mode change signal generator generates a Waiting for a signal to control the two winding switches in the differential pressure detector, and generating a detection signal to control the two bias voltage switches in the differential pressure detector. 10. The device according to claim 9, wherein the current limiters controlled by the first, second and third voltages are an N-type MOSFET, an NPN bipolar junction transistor, or N-type insulated gate bipolar transistors. 11. A device for driving a plurality of light emitting diodes, comprising: an input voltage; A plurality of LEDs, divided into a plurality of LED segments connected in series, wherein each LED segment has a positive terminal, a negative terminal, and a switch connected in parallel between the positive terminal and the negative terminal; a current limiter having a first terminal connected to said input voltage and having a second terminal; A switching voltage detector, having a first terminal connected to the second terminal of the above-mentioned current limiter, having a second terminal connected to the positive terminal of the most leading LED section among the above-mentioned plurality of LED sections, and at the above-mentioned input generating a first mode change signal when the voltage rises, and generating a second mode change signal when said input voltage falls; and a switch controller, receiving the input voltage, the first and second mode change signals, and generating a plurality of switching control signals to respectively control the plurality of LED segments, Wherein, the above-mentioned switching voltage detector further includes a pressure difference detector, and the above-mentioned pressure difference detector includes: A first voltage controlled current limiter having a first terminal, a second terminal connected to a first voltage source via a first bias voltage switch, and a third terminal connected to a common node via a first current sensor , and a bypass switch connected between the second terminal and the common node, the first voltage source connected between the input voltage and the first bias voltage switch; A second voltage-controlled current limiter having a first terminal, a second terminal connected to a second voltage source, and a third terminal connected to the common node via a second current sensor, the second voltage source being connected at between said input voltage and a second terminal of the second voltage controlled current limiter; A third voltage controlled current limiter having a first terminal, a second terminal connected to a third voltage source via a second bias voltage switch, and a third terminal connected to said common node via a third current sensor , and a bypass switch connected between the second terminal of the third voltage-controlled current limiter and the common node, the third voltage source connected between the input voltage and the second bias voltage switch ; one or more light emitting diodes connected in series between the first terminals of the second and first voltage-controlled current limiters; and One or more light emitting diodes are connected in series between the first terminals of the third and second voltage controlled current limiters. 12. The apparatus of claim 11, wherein the current limiter is a resistor. 13. The device according to claim 11, wherein the switch controller further comprises: a ripple counter receiving the first and second mode change signals and generating a plurality of counter outputs; and A plurality of switch drivers, receiving the above-mentioned multiple counter outputs, and generating the above-mentioned multiple switching control signals; Wherein, the outputs of the above-mentioned multiple counters are binary codes. 14. The device according to claim 11, wherein said switch controller further comprises: a ripple counter receiving said first and second mode change signals and generating a first plurality of outputs; a storage element receiving said first plurality of outputs and converting said first plurality of outputs into a second plurality of outputs; and A plurality of switch drivers, receiving the above-mentioned second group of multiple outputs, and generating the above-mentioned multiple switching control signals; Wherein, the above-mentioned first plurality of outputs are binary codes, and the second plurality of outputs are non-binary codes. 15. The device according to claim 11, wherein the switching voltage detector further comprises a mode change signal generator, The above mode change signal generator includes: The first comparator has a first input terminal connected to the third terminal of the above-mentioned second voltage-controlled current limiter, has a second input terminal connected to the third terminal of the above-mentioned first voltage-controlled current limiter, and generates the first a comparator output; The second comparator has a first input terminal connected to the third terminal of the above-mentioned second voltage-controlled current limiter, has a second input terminal connected to the third terminal of the above-mentioned third voltage-controlled current limiter, and generates the first two comparator outputs; and A control signal generator, receiving the output of the first and second comparators, and generating the first and second mode change signals; Wherein, the first terminal of the first voltage-controlled current limiter is connected to the positive terminal of the leading LED segment, the common node is connected to the second terminal of the current limiter, and the mode change signal is generated A wait signal is generated to control the two winding switches in the differential pressure detector, and a detection signal is generated to control the two bias voltage switches in the differential pressure detector. 16. The device according to claim 15, wherein the switch controller further comprises: a ripple counter receiving the first and second mode change signals and generating a plurality of counter outputs; and A plurality of switch drivers, receiving the above-mentioned multiple counter outputs, and generating the above-mentioned multiple switching control signals; Wherein, the outputs of the above-mentioned multiple counters are binary codes. 17. The device according to claim 15, wherein the switch controller further comprises: a ripple counter receiving said first and second mode change signals and generating a first plurality of outputs; a storage element receiving said first plurality of outputs and converting said first plurality of outputs into a second plurality of outputs; and A plurality of switch drivers, receiving the above-mentioned second group of multiple outputs, and generating the above-mentioned multiple switching control signals; Wherein, the above-mentioned first plurality of outputs are binary codes, and the second plurality of outputs are non-binary codes. 18. The device according to claim 15, wherein the current limiters controlled by the first, second and third voltages are a P-type metal-oxide-semiconductor field-effect transistor, a PNP-type bipolar junction transistor, or P-type insulated gate bipolar transistors. 19. A device for driving a plurality of light emitting diodes, comprising: an input voltage; A plurality of LEDs, divided into a plurality of LED segments connected in series, wherein each LED segment has a positive terminal, a negative terminal, and a switch connected in parallel between the positive terminal and the negative terminal; a current limiter having a first terminal connected to said input voltage and having a second terminal; A switching voltage detector, having a first terminal connected to the second terminal of the above-mentioned current limiter, having a second terminal connected to the positive terminal of the most leading LED section among the above-mentioned plurality of LED sections, and at the above-mentioned input generating a first mode change signal when the voltage rises, and generating a second mode change signal when said input voltage falls; and a switch controller, receiving the input voltage, the first and second mode change signals, and generating a plurality of switching control signals to respectively control the plurality of LED segments, Wherein, the above-mentioned switching voltage detector includes a pressure difference detector and a mode change signal generator, wherein the pressure difference detector includes: A first voltage controlled current limiter having a first terminal connected to the first terminal of the first current inductor, having a second terminal connected to the first voltage source via the first bias voltage switch, and having a third terminal connected to a common node, and a bypass switch connected between the second terminal and the common node, the first voltage source connected between the input voltage and the first bias voltage switch; A second voltage-controlled current limiter, wherein a first terminal is connected to a first terminal of a second current sensor, a second terminal is connected to a second voltage source, and a third terminal is connected to the common node, the first a second voltage source connected between said input voltage and a second terminal of the second voltage controlled current limiter; A third voltage-controlled current limiter having a first terminal connected to a first terminal of a third current sensor, having a second terminal connected to a third voltage source via a second bias voltage switch, and having a third terminal connected to the common node, and a bypass switch connected between the second terminal of the third voltage-controlled current limiter and the common node, the third voltage source connected between the input voltage and the second bias voltage between voltage switches; The first differential amplifier has two input terminals respectively connected to the first terminal and the second terminal of the first current sensor; The second differential amplifier has two input terminals respectively connected to the first terminal and the second terminal of the second current sensor; The third differential amplifier has two input terminals respectively connected to the first terminal and the second terminal of the third current sensor; one or more light emitting diodes connected in series between the second terminals of the first and second current sensors; and one or more light emitting diodes connected in series between the second ends of the second and third current sensors; And the above-mentioned mode change signal generator comprises: The first comparator has a first input terminal connected to the output terminal of the first differential amplifier, a second input terminal connected to the output terminal of the second differential amplifier, and generates a first comparator output; a second comparator having a first input connected to the output of the third differential amplifier, a second input connected to the output of the second differential amplifier, and generating a second comparator output; and A control signal generator, receiving the output of the first and second comparators, and generating the first and second mode change signals; Wherein, the second terminal of the first current sensor is connected to the positive terminal of the leading LED segment, the common node is connected to the second terminal of the current limiter, and the mode change signal generator generates a Waiting for a signal to control the two winding switches in the differential pressure detector, and generating a detection signal to control the two bias voltage switches in the differential pressure detector. 20. The device according to claim 19, wherein the current limiters controlled by the first, second and third voltages are a P-type metal-oxide-semiconductor field-effect transistor, a PNP-type bipolar junction transistor, or P-type insulated gate bipolar transistors.