LED lamp string, lamp string combination and system

Abstract

The invention discloses an LED lamp string, a lamp string combination and a system. The LED lamp string comprises a power processor and a plurality of LED lamp beads which are sequentially connected in series. The power processor comprises a reference voltage circuit, a detection resistor, a voltage comparator and a field effect transistor; the power processor is configured to receive the loop current of the LED lamp string and control the voltage comparator to obtain the detection voltage according to the resistance value of the detection resistor and the loop current; the control voltage comparator generates an adjustment voltage signal based on the magnitude relationship between the reference voltage provided by the reference voltage circuit and the detection voltage; the adjusting voltage signal increases the loop current and controls the field effect transistor to be in a conduction state and increases the loop current when the detection voltage is smaller than the reference voltage, and reduces the loop current and controls the field effect transistor to be in a disconnection state and reduces the loop current when the detection voltage is larger than the reference voltage. According to the LED lamp string provided by the invention, the stability of loop current can be maintained, and the conversion efficiency of a power supply is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to an LED light string, a light string combination and a system. Background Art

[0002] The mainstream products in the Christmas light market are high-voltage 220V LED light strings. The commonly used specifications are 50 LED lamp beads connected in series into a loop, and then several loops are connected in parallel to form finished light strings of different lengths.

[0003] Conventional LED light strings have only one LED chip inside. In order to meet the voltage requirements of the LED light string, resistors are mainly used to share the voltage on the LED light string. The higher the voltage, the more LEDs need to be connected in series. If you want to reduce the number of LEDs in series, you need to increase the resistance value of the resistor or increase the number of resistors to meet the voltage requirements.

[0004] However, when the LED light string is in operation, the current flowing through the resistance element will cause power loss, thereby reducing the power conversion efficiency. The resistance element causes the loop current of the LED light string to fluctuate, thereby affecting the stability of the light emission of the LED light string.

[0005] It can be seen that how to design an LED light string to achieve intelligent regulation of loop current and thereby ensure the current stability of the LED light string has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the invention

[0006] The present invention provides an LED light string, a light string combination and a system to solve the technical problem of how to design an LED light string to realize intelligent regulation of loop current and thereby ensure the current stability of the LED light string, so as to achieve the effect of improving the power conversion rate of the LED light string and improving the stability of the luminous brightness of the LED light string.

[0007] In a first aspect, in order to solve the above technical problems, an embodiment of the present invention provides an LED light string, including a power processor and a light-emitting unit, wherein the light-emitting unit includes a plurality of LED lamp beads connected in series in sequence;

[0008] The power processor includes a reference voltage circuit, a detection resistor, a voltage comparator and a field effect transistor; the output end of the light-emitting unit is respectively connected to the input end of the reference voltage circuit and the first input end of the field effect transistor, the output end of the reference voltage circuit is connected to the first input end of the voltage comparator, the input end of the detection resistor is respectively connected to the second input end of the voltage comparator and the output end of the field effect transistor, the output end of the voltage comparator is connected to the second input end of the field effect transistor, and the output end of the detection resistor is the common end of the power processor;

[0009] The power processor is configured to:

[0010] Receiving the loop current of the LED light string, and controlling the voltage comparator to obtain a detection voltage according to the resistance value of the detection resistor and the loop current;

[0011] Control the voltage comparator to generate an adjustment voltage signal based on the magnitude relationship between the reference voltage provided by the reference voltage circuit and the detection voltage, and send the adjustment voltage signal to the field effect transistor; the adjustment voltage signal is set to increase the loop current when the detection voltage is less than the reference voltage, and to reduce the loop current when the detection voltage is greater than the reference voltage;

[0012] When the adjustment voltage signal is for increasing the loop current, the field effect transistor is controlled to be in an on state to increase the loop current, and when the adjustment voltage signal is for reducing the loop current, the field effect transistor is controlled to be in an off state to reduce the loop current.

[0013] Preferably, the reference voltage is greater than or equal to 0.5% of an external input voltage input to the LED light string.

[0014] Preferably, each of the LED lamp beads includes two or more light-emitting LED chips connected in series.

[0015] Preferably, controlling the voltage comparator to obtain the detection voltage according to the resistance value of the detection resistor and the loop current includes:

[0016] The detection voltage is obtained by the following calculation formula:

[0017] V J =I×R J

[0018] Among them, V J represents the detection voltage, I represents the loop current, R J Indicates the resistance value of the detection resistor.

[0019] Preferably, the calculation formula of the resistance of the detection resistor is:

[0020]

[0021] Where V represents the external input voltage, R d Indicates the equivalent resistance of the light-emitting unit.

[0022] Preferably, the reference voltage circuit includes a one-time programmable memory and a bandgap reference source.

[0023] Preferably, the power processor is encapsulated in one of the LED lamp beads in the light-emitting unit loop.

[0024] Preferably, the LED light string further comprises a pair of male and female connectors;

[0025] The male and female connectors are respectively located at two ends of the LED light string to connect the LED light strings in series into a loop.

[0026] In a second aspect, the present application further provides an LED light string combination, comprising a plurality of LED light strings as described above.

[0027] In a third aspect, the present application further provides an LED system, comprising a rectifier and the LED light string combination as described above connected to the rectifier.

[0028] Compared with the prior art, the LED light string, light string combination and system disclosed in the present invention have the following beneficial effects:

[0029] (1) Maintain the stability of the LED light string circuit current, thereby ensuring the stability of the LED light string brightness;

[0030] (2) When the external input voltage is higher than the total rated voltage of the light-emitting unit, the internal circuit of the power processor processes the excess voltage. When the external input voltage is lower than the total rated voltage of the light-emitting unit, the internal circuit of the power processor releases sufficient voltage, thereby improving the conversion efficiency of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of the structure of an LED light string provided in one embodiment of the present invention;

[0032] Figure 2 It is a structural schematic diagram of an LED light string provided in one of the embodiments of the present invention, in which a power processor is encapsulated in one of the LED lamp beads in a light-emitting unit loop;

[0033] Figure 3is a schematic diagram of the structure of an LED light string connected by male and female connectors provided in one embodiment of the present invention;

[0034] Figure 4 It is a structural schematic diagram of an LED light string combination provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the description of this application, the terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0037] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are only for illustrative purposes, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0038] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0039] An embodiment of the present invention provides an LED light string, comprising a power processor and a light-emitting unit, wherein the light-emitting unit comprises a plurality of LED lamp beads connected in series in sequence;

[0040] The power processor includes a reference voltage circuit, a detection resistor, a voltage comparator and a field effect transistor; the output end of the light-emitting unit is respectively connected to the input end of the reference voltage circuit and the first input end of the field effect transistor, the output end of the reference voltage circuit is connected to the first input end of the voltage comparator, the input end of the detection resistor is respectively connected to the second input end of the voltage comparator and the output end of the field effect transistor, the output end of the voltage comparator is connected to the second input end of the field effect transistor, and the output end of the detection resistor is the common end of the power processor;

[0041] The power processor is configured to:

[0042] Receiving the loop current of the LED light string, and controlling the voltage comparator to obtain a detection voltage according to the resistance value of the detection resistor and the loop current;

[0043] Control the voltage comparator to generate an adjustment voltage signal based on the magnitude relationship between the reference voltage provided by the reference voltage circuit and the detection voltage, and send the adjustment voltage signal to the field effect transistor; the adjustment voltage signal is set to increase the loop current when the detection voltage is less than the reference voltage, and to reduce the loop current when the detection voltage is greater than the reference voltage;

[0044] When the adjustment voltage signal is for increasing the loop current, the field effect transistor is controlled to be in an on state to increase the loop current, and when the adjustment voltage signal is for reducing the loop current, the field effect transistor is controlled to be in an off state to reduce the loop current.

[0045] LED lamp beads generally use luminous LED chips to emit light. There is a nonlinear relationship between the current, voltage and power of the luminous LED chips. Connecting multiple luminous LED chips in series into an LED lamp bead can increase the total rated voltage of the LED lamp bead, reduce the current of the LED lamp bead, and thus reduce the power of the LED lamp bead while maintaining the brightness of the light.

[0046] In view of this, in a preferred embodiment of the present application, two or more LED chips are connected in series in each LED lamp bead of the light-emitting unit, so as to increase the total voltage of the light-emitting unit and reduce the circulating current of the light-emitting unit while ensuring that the brightness of a single LED lamp bead remains unchanged.

[0047] In order to ensure the stability of the loop current of the LED light string, a power processor is used to dynamically adjust the loop current according to the change of the loop current of the LED light string, such as Figure 1 As shown, the power processor includes a reference voltage circuit, a detection resistor, a voltage comparator and a field effect transistor. The output end of the light-emitting unit is connected to the input end of the reference voltage circuit and the first input end of the field effect transistor respectively. The reference voltage circuit provides a reference voltage. In this application, the reference voltage should be greater than or equal to 0.5% of the external input voltage of the input LED light string. The reference voltage circuit includes a one-time programmable memory and a bandgap reference source. The one-time programmable memory is a memory that can only be programmed once. Once the data is burned into it, it cannot be erased or reprogrammed again. The one-time programmable memory has excellent stability and can maintain the integrity of data under various environmental conditions. Due to its one-time programming characteristics, the one-time programmable memory has significant advantages in security. Compared with erasable memory, the manufacturing cost of the one-time programmable memory is relatively low because it does not require additional erasing operations. Even if the one-time programmable memory is powered off, the stored data will not be lost. The bandgap reference source is a circuit structure for providing a stable reference voltage. It uses the characteristics of semiconductor materials and realizes a stable reference voltage output by designing a suitable circuit structure. According to the reference voltage value stored in the one-time programmable memory, the bandgap reference source generates a reference voltage of corresponding size.

[0048] The output end of the reference voltage circuit is connected to the first input end of the voltage comparator, the input end of the detection resistor is respectively connected to the second input end of the voltage comparator and the output end of the field effect transistor, the output end of the voltage comparator is connected to the second input end of the field effect transistor, and the output end of the detection resistor is the common end of the power processor. There are two main types of field effect transistors selected in this application: junction field effect transistor (junction FET, referred to as JFET) and metal-oxide semiconductor field effect transistor (metal-oxide semiconductor FET, referred to as MOS-FET). Among them, MOS-FET is also called metal oxide semiconductor field effect transistor, which generally has two types of depletion type and enhancement type. Enhancement type MOS field effect transistor can also be divided into NPN type and PNP type. The field effect transistor controls the current between the source and the drain by changing the gate voltage. In the enhancement type field effect transistor, the gate voltage must reach a certain threshold value to make the current flow; in the depletion type field effect transistor, even if the gate voltage is zero, the current can flow, and the change of the gate voltage is used to adjust the magnitude of the current. In the embodiment of the present application, an enhancement type field effect transistor is selected.

[0049] The gate of the field effect transistor of the present application is connected to the output terminal of the voltage comparator, and is used to receive the voltage output by the voltage comparator to control the conduction or disconnection of the field effect transistor. Figure 1 As shown, the input end of the detection resistor is connected to the second input end of the voltage comparator and the output end of the field effect transistor respectively. According to the brightness to be achieved by a single LED lamp bead, the rated voltage of the LED light string is determined, the power processor receives the loop current of the LED light string, provides power to the power processor, the reference voltage circuit outputs the reference voltage, and inputs the reference voltage into the first input end of the voltage comparator. At this time, the field effect transistor is in the disconnected state, and the second input end of the voltage comparator is 0. Therefore, the reference voltage at the first input end of the voltage comparator is greater than the detection voltage at the second input end. The voltage comparator outputs an adjustment voltage signal, and the adjustment voltage signal is to increase the loop current. At this time, the field effect transistor is in the on state under the action of the adjustment voltage signal, so that the loop current flows through the detection resistor and increases the loop current. Because the input end of the detection resistor is connected to the second input end of the voltage comparator, the voltage comparator can collect the detection voltage at both ends of the detection resistor. The calculation formula for the detection voltage is:

[0050] V J =I×R J

[0051] Where V J represents the detection voltage, I represents the loop current, and R J Indicates the resistance value of the detection resistor.

[0052] The resistance of the detection resistor is determined according to the following formula:

[0053]

[0054] Where V represents the external input voltage, R d Indicates the equivalent resistance of the light-emitting unit.

[0055] The voltage comparator compares the reference voltage and the detection voltage. When the detection voltage is less than the reference voltage, it indicates that the loop current is less than the rated current and the loop current needs to be increased. When the detection voltage is greater than the reference voltage, it indicates that the loop current is greater than the rated current and the loop current needs to be reduced. When the field effect transistor adjusts the voltage signal to increase the loop current, it is in the on state to increase the loop current. When the voltage signal is adjusted to reduce the loop current, it is in the off state to reduce the loop current, so that the detection resistor, voltage comparator and field effect transistor are in a dynamic cycle state, so that the loop current of the LED light string is maintained constant to ensure the stability of the brightness of the LED light string. Because the time when the field effect transistor is disconnected is less than the time that the human eye can perceive, the human eye cannot perceive the flickering of the light-emitting LED lamp beads, which does not affect the brightness of the light-emitting LED lamp beads.

[0056] The external input voltage of the LED light string must be a DC voltage. In practical applications, a rectifier is required to convert the AC voltage with an effective voltage of 220V into a DC voltage. This application uses the current mainstream ordinary LED light string with 50 lamp beads in a string as a reference and compares it with the LED light string provided in this application. Table 1 shows the reference comparison data of the traditional LED light string and the LED light string of this application.

[0057] Table 1

[0058]

[0059] According to the traditional method, the specification of LED lamp beads is 2.5V~3.5V / 1mA~25mA. When 50 LED lamp beads are connected in series in a loop and 10 680-ohm resistors are connected, the measured loop current of the LED light string is 12 mA, the total voltage of the 50 LED light strings in the loop is 133V, the voltage of the resistor is 65V, and the brightness of a single light-emitting diode is 15260LUX. Calculate the total power of the LED light string, where the power of the LED lamp bead is 133*0.012=1.596W, the power of the resistor is 65*0.12=0.78W, the total power of the LED light string is 1.596W+0.78W=2.376W, and the conversion efficiency of the power supply is 198V / 220V, which is 0.9.

[0060] By adopting the LED light string disclosed in the present invention, two LED chips are encapsulated in the same LED lamp bead, the specification of a single LED is 5V-7V / 1mA-25mA, 50 LED lamp beads are connected in series in one loop, and under the action of a power processor, the loop current required by the LED light string is determined according to the brightness of a single LED. When the brightness of a single LED lamp bead is 15320LUX, the loop current required by the LED light string is 7 mA. When a stable state is reached, the total voltage of the 50 LED lamp beads in the tested loop is 208V, and the voltage of the power processor is 1V. Calculate the total power of the LED light string, where the power of the LED lamp beads is 208*0.007=1.456W, the power consumed by the power processor is 1*0.007=0.007W, and the total power of the LED light string is 1.456+0.007=1.463W. Under the same luminous brightness, compared with the traditional voltage reduction using resistor elements, the power saving is about 38%, and the calculation formula is: (2.376-1.463) / 2.376. In addition, the conversion efficiency of the power supply is 209V / 220V, reaching 0.95.

[0061] In a traditional LED light string, when the loop is connected to an 8K ohm resistor, the measured loop current of the LED light string is 9 mA, the total voltage of 50 LED light strings in the loop is 131V, the voltage of the resistor is 67V, and the brightness of a single LED light string is 12270LUX. Calculate the total power of the LED light string, where the power of the LED lamp bead is 131*0.009=1.179W, the power of the resistor is 67*0.009=0.603W, the total power of the LED light string is 1.179W+0.603W=1.782W, and the conversion efficiency of the power supply is 198V / 220V, which is 0.9.

[0062] When the brightness of a single LED lamp bead is 14500LUX, the loop current required by the LED light string is 6 mA. When the stable state is reached, the total voltage of the 50 LED lamp beads in the measured loop is 207V, and the voltage of the power processor is 2V. The total power of the LED light string is calculated, where the power of the LED lamp bead is 207*0.006=1.242W, the power consumed by the power processor is 2*0.006=0.012W, and the total power of the LED light string is 1.242+0.012=1.254W. Under the same luminous brightness, compared with the traditional resistor element voltage reduction, the power saved is approximately equal to 29.6%, and the calculation formula is (1.782-1.254) / 1.782. In addition, the conversion efficiency of the power supply is 209V / 220V, reaching 0.95, and the brightness of the single LED light string of this application is 2230LUX higher than that of the traditional single LED light string.

[0063] In a traditional light string, when the loop is connected to a 20K ohm resistor, the measured loop current of the LED light string is 4.5 mA, the total voltage of 50 LED light strings in the loop is 126 V, the voltage of the resistor is 72 V, and the brightness of a single LED is 6220 LUX. Calculate the total power of the LED light string, where the power of the LED lamp bead is 126*0.0045=0.567 W, the power of the resistor is 72*0.0045=0.324 W, the total power of the LED light string is 0.567 W+0.324 W=0.891 W, and the conversion efficiency of the power supply is 198 V / 220 V, which is 0.9.

[0064] The LED light string provided in this application also has a loop current of 4.5 mA. At this time, the brightness of a single LED is 10560 LUX. When the stable state is reached, the total voltage of the 50 LED light strings in the loop is measured to be 205 V, and the voltage of the power processor is 4 V. The total power of the LED light string is calculated, where the power of the LED lamp bead is 205*0.0045=0.9225 W, the power consumed by the power processor is 4*0.0045=0.018 W, and the total power of the LED light string is 0.9225+0.018=0.9405 W. With the power not much different from that of the traditional LED light string, the brightness of a single LED lamp bead can be increased by 4340 LUX. In addition, the conversion efficiency of the power supply is 209 V / 220 V, reaching 0.95.

[0065] From the above comparison data, it can be seen that although the loop current of the LED lamp string in the embodiment of the present invention becomes smaller, because each LED lamp bead has two light-emitting LED chips inside that emit light at the same time, the brightness of a single LED lamp bead is not affected. At the same time, the power consumed by the LED lamp string is reduced, the conversion efficiency of the power supply is improved, and the current of the LED lamp string can be kept constant, thereby ensuring the stability of the brightness of the LED lamp bead.

[0066] In this application, a conventional LED light string with 40 LED lamp beads is taken as an example to compare with the LED light string provided in this application. When the loop current of the LED light string is 9 mA, the brightness of a single LED lamp bead is about 12270 LUX, the average voltage of the 40 light-emitting diodes is 105 volts, the power is 0.945 W, and the voltage consumed by the series resistance is 93 volts, the power loss is 0.837 W, so the total power of the ordinary light-emitting diode light string is 0.945 + 0.837 = 1.782 W.

[0067] When the LED light string of the present application is used, two LED chips are encapsulated in a single LED lamp bead, and the total voltage of the LED light string circuit reaches 209V. When the brightness of a single LED lamp bead is to reach 12270LUX, the LED light string requires a circuit current of 6 mA, the total voltage of 40 energy-saving LED lamp beads is 165V, and the voltage across the power processor is 44 volts. When the voltage across the power processor is greater than 44 volts, the power processor shares the excess voltage; when the voltage across the power processor is less than 44 volts, the power processor releases enough voltage, in this way, the circuit current of the LED light string is maintained at 6 mA, the total voltage of the 44 LED lamp beads in the circuit is maintained at 165V, and the conversion efficiency of the power supply reaches more than 0.95. Although the circuit current of the LED light string is 6 mA, because there are two LED chips inside that emit light at the same time, the actual brightness of a single LED lamp bead reaches 14500LUX, which exceeds the brightness of an ordinary light-emitting diode with a circuit current of 9 mA. The power of 40 LED lamp beads is 165*0.006=0.99W, the power consumed by the power processor is 44V*0.006=0.264W, and the total power of the LED lamp string is 1.254W, which saves more than 30% of power compared with the traditional resistor element voltage reduction.

[0068] In this application, a conventional LED light string with 32 LED lamp beads is used as an example to compare with the LED light string provided in this application. When the loop current of the LED light string is 4.5 mA, the brightness of a single LED lamp bead is about 6220 LUX, the average voltage of the 32 light-emitting diodes is 101 volts, the power is 0.4545 W, and the voltage consumed by the series resistance is 97 volts, the power loss is 0.4365 W, so the total power of the ordinary light-emitting diode light string is 0.4545 + 0.4365 = 0.891 W.

[0069] When the LED light string of the present application is used, two LED chips are encapsulated in a single LED lamp bead, and the total voltage of the LED light string circuit reaches 209V. When the loop current of the LED light string is 4.5 mA, the total voltage of the 32 energy-saving LED lamp beads is 131V, and the voltage across the power processor is 78 volts. When the voltage across the power processor is greater than 78 volts, the power processor shares the excess voltage; when the voltage across the power processor is less than 78 volts, the power processor releases enough voltage, in this way, the loop current of the LED light string is maintained at 4.5 mA, the total voltage of the 44 LED lamp beads in the loop is maintained at 131V, and the conversion efficiency of the power supply reaches more than 0.95. Although the loop current of the LED light string is 4.5 mA, because there are two LED chips inside that emit light at the same time, the actual luminous brightness of a single LED lamp bead reaches 10560 LUX, which exceeds the luminous brightness of 4340 LUX of an ordinary light-emitting diode with a loop current of 4.5 mA. The power of 32 LED lamp beads is 131*0.0045=0.5859W, the power consumption of the power processor is 78V*0.0045=0.351W, and the total power of the LED lamp string is 0.9405W. Compared with the traditional resistor voltage drop, for the same loop current, the power consumption only increases by 5.5%, but the luminous brightness is about 70% higher than that of traditional LED lamp beads.

[0070] like Figure 2 As shown, in a preferred embodiment of the present application, the power processor can also be packaged in one of the LED lamp beads of the light-emitting unit loop, such as Figure 2 The LED lamp bead B shown is made into a direct plug-in type or a surface mount type during production to adapt to the automated production of LED light strings.

[0071] like Figure 3 As shown, in the preferred embodiment of the present application, the LED light string also includes two male and female connectors, which are a connecting device for electrical connection, consisting of a male head and a female head, and are electrically connected by plugging in and out, and the male and female connectors are located at both ends of the LED light string, respectively, to connect the LED light string in series into a loop. Therefore, in the present application, there are two ways to connect the LED light string to the external power supply, one is direct connection of the LED light string, and the other is connection through the male and female connectors of the LED light string.

[0072] Based on the LED light string, an LED light string combination is also disclosed in an embodiment of the present invention, including a number of LED light strings disclosed in the embodiment of the present application. A number of LED light strings can also be connected in series through male and female connectors.

[0073] Based on the LED light string combination, an LED system is also disclosed in an embodiment of the present invention, including a rectifier and the LED light string combination disclosed in the embodiment of the present application connected to the rectifier.

[0074] The rectifier receives external AC voltage to convert the AC voltage into a DC voltage suitable for the LED light string. The rectifier can be directly connected to the LED light string, or male and female connectors can be installed on the rectifier to connect several LED light strings in series through the male and female connectors.

[0075] The output end of the rectifier is connected to the input end of each LED light string, and the output end of each LED light string is connected to the input end of the rectifier to extend the length of the LED light string.

[0076] In an embodiment of the present invention, in order to solve the technical problem of how to design an LED light string to realize intelligent regulation of loop current and thus ensure the current stability of the LED light string, an LED light string, a light string combination and a system are disclosed. Among them, the LED light string includes a power processor and a light-emitting unit, and the light-emitting unit includes a plurality of LED lamp beads connected in series in sequence; the power processor includes a reference voltage circuit, a detection resistor, a voltage comparator and a field effect transistor; the output end of the light-emitting unit is respectively connected to the input end of the reference voltage circuit and the first input end of the field effect transistor, the output end of the reference voltage circuit is connected to the first input end of the voltage comparator, the input end of the detection resistor is respectively connected to the second input end of the voltage comparator and the output end of the field effect transistor, the output end of the voltage comparator is connected to the second input end of the field effect transistor, and the output end of the detection resistor is the common end of the power processor; the power processor is configured to: receive L The loop current of the ED light string, the control voltage comparator obtains the detection voltage according to the resistance value of the detection resistor and the loop current; the control voltage comparator generates an adjustment voltage signal based on the magnitude relationship between the reference voltage provided by the reference voltage circuit and the detection voltage, and sends the adjustment voltage signal to the field effect transistor; the adjustment voltage signal is set to increase the loop current when the detection voltage is less than the reference voltage, and to reduce the loop current when the detection voltage is greater than the reference voltage; when the adjustment voltage signal is to increase the loop current, the control field effect transistor is in a conducting state to increase the loop current, and when the adjustment voltage signal is to reduce the loop current, the control field effect transistor is in a disconnected state to reduce the loop current. The LED light string provided by the present application can maintain the stability of the loop current of the LED light string, thereby ensuring the stability of the luminous brightness of the LED light string. When the external input voltage is higher than the total rated voltage of the light-emitting unit, the internal circuit of the power processor processes the higher voltage. When the external input voltage is lower than the total rated voltage of the light-emitting unit, the internal circuit of the power processor releases sufficient voltage, thereby improving the conversion efficiency of the power supply.

[0077] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An LED light string, characterized in that: It includes a power processor and a light-emitting unit, wherein the light-emitting unit includes a plurality of LED lamp beads connected in series in sequence; The power processor includes a reference voltage circuit, a detection resistor, a voltage comparator and a field effect transistor; the output end of the light-emitting unit is respectively connected to the input end of the reference voltage circuit and the first input end of the field effect transistor, the output end of the reference voltage circuit is connected to the first input end of the voltage comparator, the input end of the detection resistor is respectively connected to the second input end of the voltage comparator and the output end of the field effect transistor, the output end of the voltage comparator is connected to the second input end of the field effect transistor, and the output end of the detection resistor is the common end of the power processor; The power processor is configured to: Receiving the loop current of the LED light string, and controlling the voltage comparator to obtain a detection voltage according to the resistance value of the detection resistor and the loop current; Control the voltage comparator to generate an adjustment voltage signal based on the magnitude relationship between the reference voltage provided by the reference voltage circuit and the detection voltage, and send the adjustment voltage signal to the field effect transistor; the adjustment voltage signal is set to increase the loop current when the detection voltage is less than the reference voltage, and to reduce the loop current when the detection voltage is greater than the reference voltage; When the adjustment voltage signal is for increasing the loop current, the field effect transistor is controlled to be in an on state to increase the loop current. When the adjustment voltage signal is for reducing the loop current, the field effect transistor is controlled to be in an off state to reduce the loop current.

2. The LED light string as claimed in claim 1, characterized in that: The reference voltage is greater than or equal to 0.5% of an external input voltage input to the LED light string.

3. The LED light string as claimed in claim 1, characterized in that: Each of the LED lamp beads includes two or more light-emitting LED chips connected in series.

4. The LED light string as claimed in claim 3, characterized in that: The controlling the voltage comparator to obtain the detection voltage according to the resistance value of the detection resistor and the loop current includes: The detection voltage is obtained by the following calculation formula: In J =I×R J Among them, V J represents the detection voltage, I represents the loop current, and R J Indicates the resistance value of the detection resistor.

5. The LED light string as claimed in claim 3, characterized in that: The calculation formula of the resistance value of the detection resistor is: Where V represents the external input voltage, R d Indicates the equivalent resistance of the light-emitting unit.

6. The LED light string as claimed in claim 1, characterized in that: The reference voltage circuit includes a one-time programmable memory and a bandgap reference source.

7. The LED light string as claimed in claim 1, characterized in that: The power processor is packaged in one of the LED lamp beads in the light-emitting unit loop.

8. The LED light string as claimed in claim 1, characterized in that: The LED light string also includes a pair of male and female connectors; The male and female connectors are respectively located at two ends of the LED light string to connect the LED light strings in series into a loop.

9. An LED light string combination, characterized in that: The invention comprises a plurality of LED light strings as claimed in any one of claims 1 to 8.

10. An LED system, characterized in that: The invention comprises a rectifier and an LED light string combination as claimed in claim 9 connected to the rectifier.

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